New Cosmetic Science

New Cosmetic Science

This Page Intentionally Left Blank

New Cosmetic Science Edited by

Takeo Mitsui, Ph.D. Former Senior Executive Director and Director of Research and Development Division, Shiseido Co., Ltd.

ELSEVIER A m s t e r d a m - Lausanne - New Y o r k - O x f o r d - Shannon - S i n g a p o r e - Tokyo

Notice The content of this book was based upon the latest information known to the authors as of the time it was written. However, information and knowledge changes constantly with the passing of time. In particular, the regulations applicable to cosmetic raw materials, pharmaceutical agents, cosmetic products and marketing activity vary considerably country by country and are subject to major revisions from time to time. Therefore, anyone who manufactures or sells cosmetic products must first investigate and confirm all applicable regulatory requirements. Although certain examples are provided in this book of raw materials, pharmaceutical agents, formulae, etc., these are provided for purposes of general reference only in order to explain concepts of cosmetic science. No representation or guarantee of any kind is made as to their stability, safety, efficacy or the effect of patent laws or other laws and regulations in the event of their actual use.

The Japanese edition was published by Nanzando Co. Ltd., 1993 Copyright © 1993 by Takeo Mitsui

P u b l i s h e d by: E l s e v i e r S c i e n c e B.V. P.O. B o x 211 1000 A E A m s t e r d a m The Netherlands

First edition 1997 S e c o n d i m p r e s s i o n 1998

I S B N 0 444 82654 8

© 1997 Elsevier Science B.V. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher, Elsevier Science BV, Copyright and Permissions Department, P.O. Box 521, 1000 AM Amsterdam, The Netherlands. No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Because of the rapid advances in the medical sciences, the publisher recommends that independent verification of diagnoses and drug dosages should be made. Special regulations for readers in the U.S.A.: This publication has been registered with the Copyright Clearance Center Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923. Information can be obtained from the CCC about conditions under which the photocopying of parts of this publication may be made in the U.S.A. All other copyright questions, including photocopying outside of the U.S.A., should be referred to the copyright owner, Elsevier Science BV, unless otherwise stated.

Printed in The Netherlands on acid-flee paper

Preface New Cosmetic Science was published 35 years after Cosmetic Science was edited by Tessaku Ikeda in 1957; during this interval, more than 30,000 copies of the various editions of Cosmetic Science have been sold and it is still regarded as a definitive work in this field. However, 14 years have passed since the late Dr. Ikeda made his final revisions in 1978. In these last few years, the field of cosmetic science, especially in Japan, has seen major changes, particularly in the development of new raw materials and new pharmaceutical agents, as well as in advances in manufacturing processes and technologies. The Congress of the International Federation of Societies of Cosmetic Chemists (IFSCC) in recent years have announced many important developments from Japan, and Japanese research papers have been awarded as the best paper at every Congress from 1986 to 1992. It is no exaggeration to say that cosmetic science in Japan has reached world top-class level. For these reasons, we have undertaken a comprehensive review of Dr. Ikeda's Cosmetic Science and have published this completely new book as New Cosmetic Science, New Cosmetic Science has been written to give as many people as possible, starting from scientists and technologists specializing in cosmetic research and manufacturing, students of cosmetic science, and people with a wide range of interests concerning cosmetics, a better understanding of the subject. Cosmetics, including toiletries, are closely connected with and are essential to daily life and the demand is increasing year-by-year. Many university departments of pharmacology now include lectures in cosmetic science and there is increasing general interest in the subject. Cosmetic science includes a variety of scientific disciplines starting with chemistry, pharmacology, and physical chemistry, as well as dermatology, biochemistry, physiology, engineering, analytical chemistry, fragrance chemistry, color science, and psychology. The relationship between these disciplines and cosmetics is described in Part I in New Cosmetic Science', in particular, three new chapters not described previously have been added. In addition to discussing the safety of cosmetics, the "Usefulness of Cosmetics", which is becoming a very important theme, is also described using a number of research examples. Cosmetic stability assessment is a central subject for cosmetic scientists and many aspects are based on knowledge gained over many years. The chapter on "Cosmetic Stability" has been written for a cosmetic researcher incorporating the latest findings. The last chapter of Part I is "Cosmetics and Information", which is particularly important in this information intensive age. Several databases, which are being used more

vi Preface to the English edition Toshihide Ikeda Hiroshi Itagaki Kenzo Ito Fujihiro Kanda Yoshihiro Kanda Shinobu Kato Yoshihisa Kimoto Kenji Kitamura Susumu Kobayashi Toshiaki Kobayashi

Hideo Nakajima Shoji Nakamura Tomiyuki Nanba Shoji Nishiyama Kimio Ohno Tomomi Okazaki Tsutomu Saito Izumi Sasaki Katsura Shimizu

Masahiro Tanida Katsuhiko Tokuda Akihito Torii Kenji Torii Keiichi Uehara Masaaki Uemura Youji Wachi Katsuyuki Yomogida Toshio Yoshioka

I would also like to thank Messrs. Shinji Nagashima, Yoshihiro Kanda and Tsuneo Suehiro of Shiseido Co., Ltd. for their assistance in all aspects of the editing of New Cosmetic Science. My thanks are also due to Alexander Cox for his cooperation in translating the Japanese edition into English. Finally, I would like to offer my gratitude to Ms. Yoshiko Adachi of Elsevier Science Japan in publishing the English Edition. Takeo Mitsui, Ph.D. Editor September 1996

Preface to the English edition It is now more than 3.5 years since the original pubhcation of New Cosmetic Science in Japan. During this time, it has been widely read by a great many cosmetic scientists and used as a text book or reference for several university cosmetic science courses. It has aheady been printed a second time in Japan. I am confident that the great interest in this book in Japan has been because, written by research scientists of the Shiseido Research Center who have a wealth of experience in research on cosmetic products and basic cosmetic technologies, it contains a good balance of several cutting edge technologies which are very useful in understanding cosmetic science as well as in the actual development of cosmetic products. New Cosmetic Science is now also receiving increasing attention in other countries and the number of inquires from abroad concerning it has been increasing in recent years. It has therefore been decided to publish an EngUsh edition. In its preparation, efforts have been made to make it easily understood by people of many different nationalities through slight amendments or additions to certain sections of various chapters, particularly the chapter on regulations governing cosmetics. The basic technologies discussed in Part I are all essential to cosmetic product development and the typical formulae in Part II are based on these technologies. However, if they are used as they are for cosmetic products, we cannot vouch for their safety, stability or efficacy, or that they comply with the applicable regulations or patent rights of any particular country. They were included as examples for purposes of illustration and background references. I hope that this book will prove useful to cosmetic scientists and others with an interest in cosmetics. I would like to express my great thanks to Dr. Tatsuya Ozawa, Senior Executive Director of Shiseido Co., Ltd. and Director of Research and Development Division as well as to the Shiseido research scientists whose names appear below for their contribution in the publication of the English edition. Satoru Akiu Yoshio Asaka Toshihide Ebisawa Minoru Fukuda Shoji Fukushima Fuminori Harusawa Masato Hatao Seiichi Hirose Izumi Horii Shinichi Ikeda

Yoshiyuki Kohno Masaaki Komatsu Sanae Kubo Shigenori Kumagai Yoshimaru Kumano Kiyoshi Miyazawa Hiroshi Momose Yoshihiro Morikawa Masako Naganuma Shinji Nagashima

Chiyomi Sugiyama Fukuji Suzuki Aiko Suzuki Yukitoshi Tada Toshio Takabayashi Tasuku Takamatsu Emiko Takasu Sadaki Takata Uhei Tamura Muneo Tanaka

viii Preface

widely than before, as well as books and magazines related to cosmetic science, are introduced. Part II deals with cosmetics from the viewpoint of usage including skin care cosmetics, makeup cosmetics, hair care cosmetics, fragrances, body cosmetics, and oral care cosmetics. Oral hygiene products such as toothpaste are classified as oral care cosmetics, while soaps, bath essences and salts, etc., are classified as body cosmetics. The product performance, types, main components, prescriptions and manufacturing methods are described for each item. As editor, I will be very happy if New Cosmetic Science is read by many people interested in cosmetics, and if it makes a contribution to developing cosmetic science. Finally, I would like to express my sincere appreciation to Mr. Takayoshi Toriumi, Representative Director and Ms. Keiko Kadowaki of Nanzando Co., Ltd. for their help and encouragement in publishing this book. Takeo Mitsui, Ph.D. Editor November 1992

Contents

Introduction 1. 2. 3. 4. 5. 6.

3

Purpose of cosmetics ......................................................................................... Meaning of cosmetics ........................................................................................ Classification ..................................................................................................... Quality characteristics and quality assurance .................................................... Development process of cosmetics ................................................................... Scientific background, technology and its future ..............................................

3 3 4

5 7 7

PART I Cosmetics and skin 1.1.

1.2.

1.3.

1.4.

1.5.

1.6.

13

Structure and functions of skin .......................................................................... 1.1 .l. Skin ...................................................................................................... I . 1.2. Keratinization ...................................................................................... 1.1.3. Sebaceous glands and sebum ............................................................... 1.1.4. Sweat glands and perspiration ............................................................. Biological functions of skin ............................................................................... 1.2.1. Protection ............................................................................................. 1.2.2. Thermoregulation ................................................................................ 1.2.3. Sensory perception ............................................................................... 1.2.4. Absorption ........................................................................................... 1.2.5. Other functions .................................................................................... Color of skin ...................................................................................................... 1.3.1. Skin color ............................................................................................. 1.3.2. Skin pigmentation mechanism ............................................................. 1.3.3. Methods for expressing skin color ....................................................... Methods for distinguishing skin condition ........................................................ 1.4.1. Methods for evaluating skin condition ................................................ 1.4.2. Classification of skin condition ........................................................... Acne ................................................................................................................... 1.5.1. Causes of acne ..................................................................................... 1.5.2. Development and formation of acne ................................................... 1.5.3. Skin care for acne ................................................................................ Ultraviolet light and skin ................................................................................... 1.6.1. Ultraviolet light .................................................................................... ix

13 13 15 17 18 19 19 20 20 20 21 21 21 22 24 24 25 28 28 29 30 31 32 32

Contents

X

1.6.2. Acute response to ultraviolet light ....................................................... 1.6.3. Chronic response to ultraviolet light ................................................... 1.6.4. Prevention of exposure to sunshine ..................................................... 1.7. Aging of skin ..................................................................................................... 1.7.1. Symptoms of aging .............................................................................. 1.7.2. Instrinsic aging and photoaging ........................................................... 1.7.3. External changes in aged skin .............................................................. 1.7.4. Aging changes of skin physiological functions ................................... 1.7.5. Prevention and treatment of skin aging ...............................................

.

35 37 38 38 38 39 40 44 45

2 Cosmetics and hair and nails

47

2.1. Generation of hair .............................................................................................. 2.1.1. Generation and types of hair ................................................................ 2.1.2. Composition of hair and the structure of hair follicles ........................ 2.1.3. Hair cycle ............................................................................................. .. 2.2. Form and composition of hair shaft ................................................................... 2.2.1. Form of hair ......................................................................................... 2.2.2. Color of hair ......................................................................................... 2.2.3. Structure of a hair shaft ....................................................................... 2.3. Chemical composition of hair ........................................................................... 2.3.1. Chemical composition of hair .............................................................. 2.3.2. Chemical bonds in hair ........................................................................ 2.4. Physical characteristics of hair .......................................................................... 2.4.1. Extensibility of hair ............................................................................. 2.4.2. Moisture absorption of hair ................................................................. 2.5. Hair damage ....................................................................................................... 2.5.1. Condition of hair damage .................................................................... 2.5.2. Hair damage and its causes .................................................................. 2.5.3. Split hair ............................................................................................... 2.6. Function and structure of nails .......................................................................... 2.6.1. Function and physiology of nails ......................................................... 2.6.2. Structure and composition of nails ...................................................... 2.6.3. Physical characteristics of nails ........................................................... 2.6.4. Nail damage .........................................................................................

47 47 48 50 51 51 52 53 56 56 58 59 59 60 61 61 61 64 66 66 66 68 68

.

3 Color and cosmetic color materials

70

3.1. Color .................................................................................................................. 3.1.1. Light and color ..................................................................................... 3.1.2. Color perception .................................................................................. 3.1.3. Color of coloring materials .................................................................. 3.1.4. Three attributes of color ...................................................................... 3.1.5. Expression ofcolor .............................................................................. 3.1.6. Color images and impression of color combinations .......................... 3.1.7. Makeup colors ..................................................................................... 3.2. Color materials ..................................................................................................

70 70 71 72 72 73 77 78 81

xi

Contents

3.2.1. 3.2.2. 3.2.3. 3.2.4. 3.2.5. 3.2.6. 3.2.7.

Classification of color materials .......................................................... Organic synthetic coloring agents ....................................................... Natural colors ....................................................................................... Inorganic pigments .............................................................................. Perlescent (nacreous) pigments ........................................................... Polymer powders ................................................................................. New functional pigments .....................................................................

.

82 82 86 88 93 94 96

4 Cosmetics and fragrances

99

4.1. Olfaction ............................................................................................................ 4 . I .1. Roles of olfaction ................................................................................. 4.1.2. Nature of olfaction ............................................................................... 4.1.3. Olfactory mechanism ........................................................................... 4.1.4. Body odor ............................................................................................ 4.2. Smell, fragrances and perfumery raw materials ................................................ 4.2.1. History of perfume ............................................................................... 4.2.2. Role and importance of fragrances in cosmetics ................................. 4.2.3. Physiological and psychological effects of odors ............................... 4.2.4. Classification of perfumery raw materials .......................................... 4.3. Natural perfumes ............................................................................................... 4.3.1. Major natural perfumes ....................................................................... 4.3.2. Manufacturing methods and general names ........................................ 4.3.3. Analysis of natural perfumes ............................................................... 4.4. Aroma chemicals ............................................................................................... 4.4.1. Typical aroma chemicals ..................................................................... 4.4.2. Advances in synthesis methods ........................................................... 4.5. Fragrance compounds ........................................................................................ 4.5.1. Base compounds .................................................................................. 4.5.2. Other base compounds ......................................................................... 4.6. Perfume creation ................................................................................................ 4.6.1. Creation ................................................................................................ 4.6.2. Preference ............................................................................................ 4.6.3. Fragrance strength and perfume dosage .............................................. 4.6.4. Odor and color changes ....................................................................... 4.6.5. Safety ...................................................................................................

99 99 100 100 100 101 101 101 102 103 104 104 104 108 111 111 111 111 114 115 116 116 118 118 118 119

.

5 Raw materials of cosmetics 5.1. Oily materials .................................................................................................... 5.1 .1. Oils and fats ......................................................................................... 5.1.2. Wax esters ............................................................................................ 5.1.3. Hydrocarbons ....................................................................................... 5.1.4. Higher fatty acids ................................................................................. 5.1.5. Higher alcohols .................................................................................... 5.1.6. Esters .................................................................................................... 5.1.7. Silicones ...............................................................................................

121 121 122 122 124 125 126 127 128

xii

5.2.

5.3.

5.4.

5.5. 5.6.

5.7. 5.8.

.

Contents

5.1.8. Others ................................................................................................... Surface active agents ......................................................................................... 5.2.1. Anionic surfactants .............................................................................. 5.2.2. Cationic surfactants ............................................................................. 5.2.3. Amphoteric surfactants ........................................................................ 5.2.4. Non-ionic surfactants ........................................................................... 5.2.5. Other surfactants .................................................................................. Humectants ........................................................................................................ 5.3.1. Glycerin ............................................................................................... 5.3.2. Propyleneglycol .................................................................................. 5.3.3. 1,3-Butylene glycol .............................................................................. 5.3.4. Polyethylene glycol ............................................................................. 5.3.5. Sorbitol ................................................................................................ 5.3.6. Sodium lactate ..................................................................................... 5.3.7. Sodium 2-pyrrolidone-5-carboxy late .................................................. 5.3.8. Sodium hyaluronate ............................................................................. Polymers ............................................................................................................ 5.4.1, Thickening agents ................................................................................ 5.4.2. Film formers ........................................................................................ Ultraviolet absorbents ........................................................................................ Antioxidants ....................................................................................................... 5.6.1, Auto-oxidation mechanism .................................................................. . . ........................................................................ 5.6.2. Prevention of oxidation 5.6.3. Confirmation of efficacy of antioxidants ............................................ Sequestering agents ........................................................................................... Other raw materials ........................................................................................... 5.8.1. Metallic soaps ......................................................................................

6 Cosmetics and pharmaceutical agents 6.1. Whitening agents ............................................................................................... 6.1.1. Arbutin ................................................................................................. 6.1.2. Kojic acid ............................................................................................. 6.1.3. Vitamin C and its derivatives .............................................................. 6.2. Hair growth promoters ....................................................................................... 6.2.1. Vasodilators ......................................................................................... 6.2.2. Nourishing agents ................................................................................ 6.2.3. Estrogens (follicle hormone) ............................................................... 6.2.4. Hair root activating agents ................................................................... 6.2.5. Humectants .......................................................................................... 6.3. Skin-care agents ................................................................................................. 6.3.1. Antiinflammatory agents ..................................................................... 6.3.2. Astringents ........................................................................................... 6.3.3. Refrigerants .......................................................................................... 6.3.4. Vitamins ............................................................................................... 6.3.5. Hormones ............................................................................................. 6.3.6. Antihistamines .....................................................................................

129 129 129 131 131 132 134 134 135 135 136 136 136 136 136 137 138 138 140 142 142 142 144 145 146 146 146

148 148 148 149 150 151 151 151 152 152 152 152 152 153 153 153 155 155

Contents

6.3.7. Others ................................................................................................... 6.4. Anti-acne agents ................................................................................................ 6.4.1. Sebum secretion inhibitors .................................................................. 6.4.2. Corneocyte desquamating agents ........................................................ 6.4.3. Antibacterial agents ............................................................................. 6.4.4. Others ................................................................................................... 6.5. Anti-dandruff and anti-itching agents ............................................................... 6.5.1. Corneocyte desquamating agents ........................................................ 6.5.2. Antiseborrheic agents ......................... ............................................. 6.5.3. Antibacterial agents ............................................................................. 6.5.4. Antiinflammatory agents ..................................................................... 6.5.5. Antipruritic agents ............................................................................... Antiperspirants and deodorants ......................................................................... 6.6. 6.6.1. Antiperspirants ..................................................................................... 6.6.2. Antibacterial agents ............................................................................. 6.6.3. Deodorants ........................................................................................... 6.7. Oral care agents ................................................................................................. 6.7. I . Anticariogenic agents .......................................................................... 6.7.2. Antiperiodontic agents ......................................................................... 6.7.3. Oral deodorants .................................................................................... 6.7.4. Antitarta agents .................................................................................... 6.7.5. Tar cleansing agents ............................................................................ 6.8. Others ................................................................................................................. 6.8.1. Vitamins ............................................ ............................................. 6.8.2. Hormones ............................................................................................. 6.8.3. Amino acids ......................................................................................... 6.8.4. Extracts from natural resources ...........................................................

.

7 Cosmetics and physical chemistry 7.1. Colloid and interface science of cosmetics ....................................................... 7 . I .1. Colloids and interfaces ........................................................................ 7.1.2. Properties of surfactants ...................................................................... 7.1.3. Solubilization and microemulsions ..................................................... 7.1.4. Emulsions ............................................................................................ 7.1.5. Liposomes (vesicle) ............................................................................. 7.1.6. Properties of powders .......................................................................... 7.2. Rheology of cosmetics ....................................................................................... 7.2.1, Meaning of rheology in cosmetics ....................................................... 7.2.2. Flow forms ........................................................................................... 7.2.3. Rheology measurement methods .........................................................

.

8 Stability of cosmetics 8.1. Stability of base formulae and its testing .......................................................... 8.1. 1. General preservation tests .................................................................... 8.1.2. General performance and effectiveness tests ......................................

... XI11

155 156 156 156 157 157 157 158 158 158 158 158 158 159 159 159 160 160 161 162 162 162 162 162 163 163 164

165 165 165 167 173 174 180 180 183 183 183 184

191 191 191 194

xiv

Contents

8.1.3. Aerosol stability tests ........................................................................... 8.1.4. Special accelerated stability tests ........................................................ 8.2. Stability of pharmaceutical agents and test methods ......................................... 8.2.1. Quality assurance for pharmaceutical agents in cosmetics ................. 8.2.2. Stability tests for quasi drug products ................................................. 8.3. Stability of mass-produced cosmetics ............................................................... 8.4. Assurance stability based on usage environment ..............................................

.

9 Preservation of cosmetics 9.1 . Need for adding preservatives to cosmetics ...................................................... 9.2. Primary and secondary contamination .............................................................. 9.3. Antimicrobial agents .......................................................................................... 9.3.1 . Preservatives ........................................................................................ 9.3.2. Disinfectants and germicides ............................................................... 9.3.3. Characteristics required of antimicrobial agents ................................. 9.4. Antimicrobial agents used in cosmetics ............................................................ 9.5. Methods for evaluating the effectiveness of preservatives ............................... 9.6. GMP and its validation ......................................................................................

.

10 Safety of cosmetics 10.1. Basic concept of cosmetic safety ....................................................................... 10.2. Safety test items and evaluation method ........................................................... 10.2.1. Skin irritation ....................................................................................... 10.2.2. Sensitization (allergenicity) ................................................................. 10.2.3. Phototoxicity ........................................................................................ 10.2.4. Photosensitization (photoallergenicity) ............................................... 10.2.5. Eye irritation ........................................................................................ 10.2.6. Toxicity ................................................................................................ 10.2.7. Mutagenicity ........................................................................................ . . ........................................................................... 10.2.8. Reproductive toxicity 10.2.9. Absorption, distribution, metabolism, excretion ................................. 10.2.10. Testing on humans (patch test, usage test) .......................................... 10.3. Animal test alternatives .....................................................................................

.

11 Usefulness of cosmetics I 1.1. Usefulness of cosmetics ..................................................................................... 11.2. Research on usefulness of cosmetics ................................................................. 11.2.1. Physiological usefulness ...................................................................... 11.2.2. Physicochemical usefulness ................................................................ 1I .2.3. Psychological usefulness ..................................................................... 1 1 .3. Examples of usefulness research ....................................................................... 11.3.1. Examples of research on physiological usefulness ............................. I 1.3.2. Examples of research on physicochemical usefulness ........................ 11.3.3. Examples of research on psychological usefulness ............................. 1I .4. Future direction of cosmetic usefulness ............................................................

194 195 196 196 197 197 198

199 199 200 201 201 201 202 202 205 206

209 209 210 210 211 212 212 213 213 214 214 215 215 216

218 218 218 218 219 219 220 220 227 231 233

Contents

.

xv

12 Cosmetics and containers

235

12.1. Characteristics required by cosmetic containers ............................................... 12.1.1. Quality maintenance ............................................................................ 12.1.2. Functional design ................................................................................. 12.1.3. Optimum packaging ............................................................................. 12.1.4. Economy .............................................................................................. 12.1.5. Sales promotion ................................................................................... 12.2. Types of cosmetic containers ............................................................................ 12.2.1. Narrow-mouth bottles (containers) ...................................................... 12.2.2. Wide-mouth bottles (containers) ......................................................... 12.2.3. Tubes .................................................................................................... 12.2.4. Tubular containers ............................................................................... 12.2.5. Powder containers ................................................................................ 12.2.6. Compact containers ............................................................................. 12.2.7. Stick containers .................................................................................... 12.2.8. Pencil containers .................................................................................. 12.2.9. Applicator containers ........................................................................... 12.3. Cosmetic container materials ............................................................................ 12.3.I . Types of materials ................................................................................ 12.3.2. Forming and processing methods ........................................................ 12.4. Design and quality assurance of cosmetic containers ....................................... 12.4.1. Container design procedure ................................................................. 12.4.2. Material test methods and specifications ............................................. 12.5. Trends in container materials ............................................................................ 12.5.1. Materials and processing methods ....................................................... 12.5.2. Environment friendliness .....................................................................

235 235 237 237 238 238 238 239 239 239 239 240 240 240 241 241 241 241 243 245 245 245 246 246 247

.

13 Aerosol technology in cosmetics

13.1. Principle of aerosols and their components ....................................................... 13.1.1. Principle of aerosols ............................................................................ 13.1.2. Components of an aerosol ................................................................... 13.2. Aerosol propellants ............................................................................................ 13.2.1. Liquefied gases .................................................................................... 13.2.2. Compressed gas ................................................................................... 13.3. Aerosol concentrates (discharged substances) .................................................. 13.3.1. Solubility test ....................................................................................... 13.3.2. Internal pressure test ............................................................................ 13.3.3. Discharge test ....................................................................................... 13.3.4. Low temperature test ........................................................................... 13.3.5. Other testing ......................................................................................... 13.4. Aerosol containers ............................................................................................. 13.4.1. Pressure-resistant containers ................................................................ 13.4.2. Valves, actuators, spouts and caps ....................................................... 13.5. Regulations on aerosols ..................................................................................... 13.6. Aerosol manufacturing methods ........................................................................

248 248 248 249 249 249 250 250 251 251 251 251 251 251 251 252 253 254

xvi

Contents

13.6.1. Manufacturing processes ..................................................................... 13.6.2. Filling methods for propellant gas ....................................................... 13.7. Precautions when using aerosol cosmetics ........................................................ 13.8. Recent developments in aerosol technology ..................................................... 13.8.1, Special aerosol containers ................................................................... 13.8.2. Making aerosols environment friendly ................................................

.

14 Analytical chemistry of cosmetics 14.1. Analysis of cosmetics ........................................................................................ 14.1.1. General separation techniques ............................................................. 14.1.2. Column chromatography ..................................................................... 14.1.3. Gas chromatography ............................................................................ 14.1.4. High performance liquid chromatography .......................................... 14.1.5. X-ray diffractiometry ........................................................................... 14.1.6. Infrared spectrophotometry ................................................................. 14.1.7. Nuclear magnetic resonance ................................................................ 14.1.8. Mass spectrometry ............................................................................... 14.1.9. Atomic emission spectrophotometry, atomic absorption spectrophotometry ........................................................................................... 14.1.10. Summary of analysis on cosmetics ...................................................... 14.2. Analysis of skin and hair ................................................................................... 14.2.1. Analysis of skin ................................................................................... 14.2.2. Analysis of hair .................................................................................... 14.3. Automation of analysis ......................................................................................

.

15 Cosmetic manufacturing equipment 15.1. Grinders ............................................................................................................. 15.2. Powder mixing equipment ................................................................................. 15.3. Dispersion and emulsification equipment ......................................................... 15.3.1. Propeller mixer .................................................................................... 15.3.2. Disper ................................................................................................... 15.3.3. Homomixer .......................................................................................... 15.3.4. Homogenizer ........................................................................................ 15.3.5. Colloid mill .......................................................................................... 15.3.6. Pebble mill ........................................................................................... 15.3.7. Ultrasonic emulsifier ........................................................................... 15.4. Kneading equipment .......................................................................................... 15.4.1. Kneader ................................................................................................ 15.4.2. Roller ................................................................................................... 15.4.3. Gyratory grinder .................................................................................. 15.5. Cooling equipment ............................................................................................ 15.5.1. Cooling equipment employing stirring ................................................ 15.5.2. Cooling equipment employing heat exchange ..................................... 15.6. Molding machines ............................................................................................. 15.6.1. Lipstick molding machines ..................................................................

254 255 255 256 256 256

257 257 258 259 260 263 266 268 268 270 272 272 273 273 276 277

280 281 281 283 283 283 284 284 285 285 285 285 285 285 285 285 286 286 288 288

Contents

xvii

15.6.2. Foundation molding machines ............................................................. 15.7. Filling and packaging machines ........................................................................

289 291

.

16 Regulations on cosmetics ~

16.1. Regulations concerning cosmetics in Japan ...................................................... 16.1.1. Regulations in Pharmaceutical Affairs Law concerning cosmetics and quasi-drug products ....................................................................... 16.1.2. Regulations on manufacture and sale of cosmetics and quasi-drug products ................................................................................................ 16.2. Laws relating to cosmetics in Japan .................................................................. 16.2.1. Regulations relating to raw materials .................................................. 16.2.2. Laws relating to product contents ........................................................ 16.2.3. Regulations concerning containers ...................................................... 16.2.4. Regulations on marketing .................................................................... 16.3. Regulations on cosmetics in other countries (Asia, Oceania, North America, South America and Europe) .............................................................................. 16.3.1. Asia ...................................................................................................... 16.3.2. Oceania ................................................................................................ 16.3.3. North America ..................................................................................... 16.3.4. South America ..................................................................................... 16.3.5. Europe ..................................................................................................

.

17 Cosmetics and information 17.1. Importance of information in research and development .................................. 17.1.1. Documentation activities ..................................................................... 17.1.2. Information sources ............................................................................. 17.2. Books and journals containing cosmetic-related information ........................... 17.2.1. Books (monographs) ............................................................................ 17.2.2. Journals ................................................................................................ 17.3. Databases ........................................................................................................... 17.3.1. Definition of a database ....................................................................... 17.3.2. On-line information retrieval systems .................................................

292 292 294 295 297 298 298 302 303 304 304 306 307 307 307

310 310 310 311 312 314 314 316 316 316

PART I1

.

1 Skin care cosmetics 1 .1 . Purposes. functions and roles of skin care cosmetics ........................................ 1.1.1. Purposes of skin care cosmetics .......................................................... 1.1.2. Functions of skin care cosmetics ......................................................... 1. I .3. Roles of skin care cosmetics ................................................................ 1.2. Face cleansing cosmetics ................................................................................... 1.2.1. Purposes and functions of face cleansing cosmetics ........................... 1.2.2. Main ingredients of cleansing foams ................................................... 1.2.3. General manufacturing methods for cleansing foams ......................... 1.2.4. Types of cleansing foam ......................................................................

319 319 319 320 320 323 323 323 324 325

xviii

Contents

1.3. Lotion ................................................................................................................. 1.3.1. Purposes and functions of lotion ......................................................... 1.3.2. Main ingredients of lotions .................................................................. 1.3.3. General methods for manufacturing lotions ........................................ 1.3.4. Types of lotion ..................................................................................... 1.4. Milky lotions...................................................................................................... 1.4.1. Purposes and functions of milky lotions.............................................. 1.4.2. Main ingredients of milky lotions ....................................................... 1.4.3. General manufacturing methods for milky lotions.............................. 1.4.4. Types of milky lotion ........................................................................... 1.5. Creams ............................................................................................................... 1.5.1. Purposes and functions of creams ....................................................... 1.5.2. Main ingredients of creams ................................................................. 1 S.3. General manufacturing methods for creams........................................ 1.5.4. Types of cream .................................................................................... 1.6. Gels .................................................................................................................... 1.6.1. Purposes and functions of gels ............................................................ 1.6.2. Main ingredients of gels ...................................................................... 1.6.3. General manufacturing methods for gels ............................................. 1.6.4. Types of gel ......................................................................................... 1.7. Essences (beauty lotions)................................................................................... 1.7.1. Purposes and functions of essences ..................................................... 1.7.2. Main ingredients of essences ............................................................... 1.7.3. General manufacturing methods for essences ..................................... 1.7.4. Types of essence .................................................................................. 1.8. Packs and masks ................................................................................................ 1.8.1. Purposes and functions of packs and masks ........................................ 1.8.2. Main ingredients of packs and masks .................................................. 1.8.3. General manufacturing methods for packs and masks ........................ 1.8.4. Types of pack and mask ...................................................................... 1.9. Shaving" cosmetics ............................................................................................. 1.9.1. Purposes and functions of shaving cosmetics...................................... 1.9.2. Types of shaving cosmetics ................................................................. I .10. Other cosmetics .................................................................................................

.

2 Makeup cosmetics 2.1. 2.2. 2.3. 2.4. 2.5.

History of makeup cosmetics ............................................................................ Types and functions of makeup cosmetics ........................................................ Types and forms of makeup cosmetics ............................................................. Raw materials used in makeup cosmetics ......................................................... Face powder and pressed powder ...................................................................... 2.5.1. Loose powder ....................................................................................... 2.5.2. Compact powder .................................................................................. 2.5.3. Paper sheet-type face powder .............................................................. 2.5.4. Liquid face powder .............................................................................. 2.5.5. Other powder cosmetics ......................................................................

327 327 328 330 330 335 335 337 338 339 341 341 342 343 345 351 351 351 353 353 354 354 354 355 355 357 357 359 359 360 363 363 363 367

370 370 370 371 371 375 376 376 377 371 377

Contents

2.6. Foundations ........................................................................................................ 2.6.1. Powdery foundations ........................................................................... 2.6.2. Dual-use foundations ........................................................................... 2.6.3. Cake-type foundations ......................................................................... 2.6.4. Oil-based foundations .......................................................................... 2.6.5. O/W emulsion foundations .................................................................. 2.6.6. W/O emulsion foundations ............................................ .......... Lipsticks and rouge ............................................................................................ 2.7. 2.7.1. History of lipstick ................................................................................ 2.7.2. Quality requirements for lipsticks ....................................................... . . 2.7.3. Raw materials of lipsticks .................................................................... 2.8. Rouges (rouge. cheek color and blush-on products) ......................................... 2.9. Eye makeup ....................................................................................................... 2.9.1. History and types ................................................................................. 2.9.2. Points for attention with eye makeup products ................................... 2.9.3. Eyeliner ................................................................................................ 2.9.4. Mascara .......................................................................................... 2.9.5. Eye shadow .......................................................................................... 2.9.6. Eyebrow cosmetics .............................................................................. 2.9.7. Other products ...................................................................... 2.10. Manicure preparations ....................................................................................... 2.10.1. Functions and types ............................................................................. 2.102. Nail enamel .......................................................................................... 2.10.3. Enamel remover ................................................................................... 2.10.4. Nail treatment ...................................................................................... 2.103. Other products .....................................................................................

.

3 Hair care cosmetics

3.1. Hair cleansing cosmetics ................................................................................... 3.1.1, Shampoo .............................................................................................. 3.1.2. Rinses ................................................................................................... 3.1.3. One-step shampoo (shampoo having both shampoo and rinse functions) ................................................................................ 3.2. Hair growth promoters ....................................................................................... 3.2.1. Introduction ................................................................................ 3.2.2. Types of hair growth promoter ............................................................ 3.2.3. Causes of hair loss ...................................................................... 3.2.4. Active ingredients of hair growth promoters ....................................... 3.2.5. Methods of evaluating hair growth promoters .................................... 3.3. Hair grooming cosmetics ................................................................................... 3.3.1. Types of hair styling preparation ....................................... 3.3.2. Types of hair treatment preparation ................................... 3.4. Permanent waving lotion ................................................................. 3.4.1. History ................................................................................................. 3.4.2. Permanent waving mechanism ................................................. 3.4.3. Types of permanent waving lotion ......................................................

xix

378 379 380

381 382 383 384 385 385 386 386 388 390 390 390 391 393 395 396 398 398 398 399 402 403 403

406 406 407 410 412 413 413 414 414 415 416 418 418 424 426 426 421 428

xx

Contents

3.5. Hair color. hair bleach ....................................................................................... 3.5.1. History ................................................................................................. 3.5.2. Classifications of hair color and their mechanisms ............................. 3.5.3. Types of hair color ............................................................................... 3.5.4. Hair bleach ...........................................................................................

.

4 Fragrance products 4.1. Types of fragrance product ................................................................................ 4.2. Perfume .............................................................................................................. 4.2.1. Manufacturing methods for perfumes ................................................. 4.2.2. Alcohol used for perfumes ................................................................... 4.2.3. Classification of perfume ..................................................................... 4.2.4. Choosing a perfume ............................................................................. 4.2.5. Wearing perfume ................................................................................. 4.2.6. Keeping a perfume at its best .............................................................. 4.3. Men’s cologne ...................................................................................................

.

430 430 431 432 436

439 439 439 440 440 441 442 442 442 445

5 Body cosmetics

446

5.1. Soap ................................................................................................................... 5.1.1. History of soap ..................................................................................... 5.1.2. Raw materials of soap .......................................................................... 5.1.3. Soap manufacturing methods .............................................................. 5.1.4. Properties of soap ................................................................................ 5.1.5. Types of soap ....................................................................................... 5.2. Body shampoo ................................................................................................... 5.2.1. Functions required of body shampoos ................................................. 5.2.2. Types of body shampoo ....................................................................... 5.2.3. Main ingredients of body shampoo ..................................................... 5.3. Suncare products ................................................................................................ 5.3.1. Methods for assessing protection against ultraviolet rays ................... 5.3.2. Types of suncare base .......................................................................... 5.3.3. Types of suncare product ..................................................................... 5.4. Hand care products ............................................................................................ 5.5. Deodorant cosmetics .......................................................................................... 5.5.1. Body odor ............................................................................................ 5.5.2. Functions and ingredients of deodorant cosmetics .............................. 5.5.3. Types of deodorant cosmetics ............................................................. 5.6. Bleach and depilatories ...................................................................................... 5.6.1. Bleach (or discolor) ............................................................................. 5.6.2. Depilatories .......................................................................................... 5.7. Bath preparations ............................................................................................... 5.7.1. History and purposes of bath preparations .......................................... 5.7.2. Types and functions of bath preparations ............................................ 5.8. Insect repellents .................................................................................................

446 446 447 448 450 450 453 454 455 455 457 457 459 460 464 466 466 466 467 470 470 470 473 473 474 477

Contents

.

6 Oral care cosmetics

XXl

479

6.1. Dentifrices ......................................................................................................... 6.1.1. History of dentifrices ........................................................................... 6.1.2. Classification of oral cleansing products ............................................. 6.1.3. Dentifrices............................................................................................ 6.1.4. Mouthwash ........................................................................................... 6.2. Mouth freshener.................................................................................................

479 479 479 480 487 489

Index ...........................................................................................................................

491

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Introduction

1. Purpose of cosmetics 2. Meaning of cosmetics 3. Classification 4. Quality characteristics and quality assurance 5. Development process of cosmetics 6. Scientific background, technology and its future

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Introduction

1. Purpose of cosmetics Cosmetics are becoming of more importance in daily life; they are used regularly by increasing numbers of people and very large quantities are consumed each year. When were cosmetics first used by people? Even if we examine the history of cosmetics, it is extremely difficult to say when cosmetics were first used. Archaeological excavations confirm that they were used in the early stone age and we can safely assume that cosmetics have a very long history. Why did early societies use cosmetics? If we examine the purpose of cosmetics, the most obvious is protection of the body from the elements of nature, such as heat and sunlight. Early people painted themselves with oils or mixtures of oils, clays and plant materials to protect themselves against dryness from cold, burns from strong sunlight, and irritation from insect bites. Additionally, cosmetics were used for religious purposes. Fragrant woods for example were burnt to produce smoke and incense that would ward off evil spirits. Further protection was afforded to an individual by painting the body to guard against evil. As societies came into the age of enlightenment, however, most of these purpose of cosmetics disappeared. The main purposes for using cosmetics in modern society are for personal hygiene, to enhance attractiveness through use of makeup, to improve selfesteem and promote tranquillity, to protect skin and hair from damaging ultraviolet light, pollutants, and other environmental factor, to prevent aging, and in general to help people enjoy a more full and rewarding life.

2. Meaning of cosmetics How do we define a cosmetic? The definition of cosmetic under the law varies slightly between countries but in general terms "cosmetic" means any article intended to be used by means of rubbing, sprinkling or by similar application to the human body for cleaning, beautifying, promoting attractiveness, altering the appearance of the human body, and for maintaining health of the skin and hair, provided that the action of the article on the human body is mild. The Japanese Pharmaceutical Affairs Law regulates both cosmetics and so-called quasi-drugs. Quasi-drugs are products which are applied to the body for the purposes of cleaning teeth, deodorants, and hair colors, etc., but they "should be for alleviation of conditions

4 New cosmetic science

of the body but not for prevention and treatment of illness; they should not be designed to affect body structure and functions" The current Pharmaceutical Affairs Law makes a clear distinction between cosmetics, quasi-drugs, and pharmaceuticals. The former two categories of product are for use by healthy people to maintain personal hygiene and to maintain a favorable personal appearance. Consequently the physiological activities of cosmetics must be mild. In contrast, pharmaceutical drugs are used for treatment and prevention of illness and they have an effect on the structure and functions of the body. Since cosmetics and quasi-drugs are often used on a daily basis over long periods of time, safety without side effects is of paramount importance, and they must be completely safe without side effects. By contrast, pharmaceutical drugs for medical use are used only over short time periods to treat medical conditions. Their primary purpose is to cure illness, and they must therefore be therapeutically effective. Sometimes slight side effects of these drugs cannot be avoided. In summary, cosmetics and quasi-drugs are quite different from pharmaceutical drugs in use, purpose, and effects. New Cosmetics Science describes both cosmetics and quasi-drugs and when there is no particular reason for classifying these two groups of products separately, they are called cosmetics for convenience.

3. Classification Cosmetics (including quasi-drugs) can be classified according to their use and area of application. In addition, they can be classified by composition and structure. However, New Cosmetics Science uses the system shown in Table 1 based on usage and classifies cosmetics into skin care cosmetics, makeup cosmetics, body cosmetics, hair care cosmetics, oral cosmetics and fragrances. Skin care cosmetics are called facial cosmetics and they are mainly used on the face. There are three main usage purposes: cleansing, skin balance, and protection. Makeup cosmetic are mainly used on the face. Other makeup cosmetics include nail enamel. Face makeups are divided into base makeup and point makeups. Body cosmetics include suncare and suntan cosmetics, antiperspirants, deodorants, hair remover, bleaches depilatories, soaps, hand care products and bath preparations. A special product in the body cosmetics group is insect repellents. Hair care cosmetics include shampoos, treatments, and hair styling preparations as well as permanent wave agents and hair dyes. Other products in the group include hair growth promoters and scalp treatments. Oral care cosmetics primarily include toothpastes and products such as mouth washes. Fragrances are mainly used on the body but sometimes on the scalp hair and earlobes. Typical fragrance cosmetics are perfumes, but there are also eau de colognes made by varying the amount of fragrance used. These cosmetics are all used in daily life. The value of cosmetic shipments in Japan is second only to that in the USA. In terms of the value by type, skin care cosmetics are the largest followed by hair care cosmetics and makeups. Fragrances such as perfumes and

Introduction to cosmetic science Table 1. Classincation of cosmetics

Classification

Skin care cosmetics

Makeup cosmetics CO 5-'

Body cosmetics

1 3 Hair care Cosmetics OS

u

Scalp care Cosmetics

Oral care Cosmetics Fragrances

Main Products

Usage Cleansers

Face Cleansing Creams and Foams

Conditioners

Lotions, Packs, Massage Creams

Protectors

Milky Lotions, Moisture Creams

Base makeups

Foundations, Face Powders

Point Makeups

Lipstick, Blushers, Eye Shadow, Eye Liners

Nail Care

Nail Enamels, Nail Polish Removers

Bath

Soaps, Liquid Cleansers, Bath Preparations

Suncares and Suntans

Sunscreen Creams, Sun Oils

Antiperspirants and Deodorants

Deodorant Sprays

Bleaching, Depilatory

Bleaching Creams, Depilatory Creams

Insect Repellents

Insect Repellent Lotions and Sprays

Cleansing

Shampoos

Treatments

Rinses, Hair Treatments

Hair Styling

Hair Mousses® , Hair Liquids, Pomades

Permanent Waves

Permanent Wave Lotions (Agent No.l, No.2)

Hair Colors and Bleaches

Hair Colors, Hair Bleaches, Color Rinses

Hair Growth Promoters

Hair Growth Promoters, Hair Tonics

Treatments

Scalp Treatments

Toothpastes

Toothpastes

Mouthwashes

Mouthwashes

Fragrances

Perfumes, Eau de Colognes

eau de colognes are used less compared to the USA and Europe. This may be because of differences in lifestyle and body constitution.

4. Quality characteristics and quality assurance 4.1. Quality characteristics of cosmetics Generally, "quality" is determined by the satisfaction of the user (consumer). In the industrial situation, quality is determined at three points: (1) design, (2) manufacture and (3) sales. From each point, there are requirements necessary to satisfy the high quality characteristics. Economics and market timing are also important factors to consider. When designing, manufacturing and marketing cosmetics, the basic quality requirements are safety, stability, efficacy, and usability (feeling and ease of use); usability includes preference factors such as smell, color, and package design, which are determined by the user's personal taste. The quality characteristics are summarized in Table 2.

5

6

New cosmetic

science Table 2. Quality characteristics of cosmetics

Safety

Lack of Skin irritation, Skin sensitivity, Oral toxicity, Mixing with other materials, Harmlessness

Stability

Quality change. Color change. Smell change. Bacterial contamination, etc.

Usability

1. Feeling (sensibility, moisturizing, smoothness) 2. Ease-of-Use(form, size, weight, composition, performance, portability, etc.) 3. Preference (smell, color, design, etc.)

Efficacy

Moisturizing effect, UV protective effect, cleansing effect, coloring effect, etc.

Table 3(1). Cosmetics quality assurance

—Safety Assurance a; o 03

m—

<3 o O

Q. u ' 1 >

—Various Safety Tests and Patch Tests —Toxic Heavy Metal Tests (Pb, As, etc.) —Color Stability Test (Color stability) —Photoresistance Test (fading with light) —Smell Stability Test (Smell stability) Test)

A

—Preservation Test —Pharmaceutical Agent Stability Test (Efficacy assurance) 1—Physico-chemical Stability Test —Usability Test (Sensory Test) —Usability Assurance— —Physico-chemical Test(Rheological Measurement, etc.)

Table 3(2). Cosmetics quality assurance

I—Contents Protection Assurance-

-Material Suitability Assurance

-Materials Safety Assurance-

(1H

-Function Assurance-Usage Safety-Disposability Guarantee-

-Light Protection Test -Permeability Test -Smell Protection Test (to detect changes in smell.) I—Chemical Resistance Test Anti-corrosion Test Sun proof Test ^Substances requiring caution in Materials (Formalin, etc.) -Safety Standards (Ministry of Health and Welfare Guidelines, etc.) -Safety Confirmation Test J—Human Engineering Functional Test '—Physical Function Test Usage Environment Test Usage Method Ease of Disposal (Efficiency, etc.) Safety (Incineration Safety)

£ £:

Introduction to cosmetic science 7 4.2. Quality assurance of cosmetics The definition of quality assurance is given in the Quality Assurance Guidebook}^ as "guaranteeing product quality to ensure full customer confidence and satisfaction when purchasing as well as when using the product. In addition, the quality must permit longterm usage." This definition indicates the importance of quality assurance in quality control system for economically manufacturing products of a quality that meets user requirements (Japan Industrial Standard JIS8101). In addition, the definition shows that the cosmetics industry has a responsibility to protect the safety of the consumer. Each of the research, manufacturing and sales departments deals with quality assurance of cosmetics; Tables 3(1) and 3(2) outline the quality assurance system utilized by the design and R&D departments.

5. Development process of cosmetics Fig, 1 shows the flow of one manufacturing development cycle (development process) for cosmetics from basic research to manufacturing research and production based on the commercialization plans. In the development of cosmetics, the seeds of basic and applied research must first bear fruit. Research into the early stage of the development of cosmetics includes the development of new raw materials, new formulation techniques and new concepts for the utilization of seeds from dermatological research. In recent years, new raw materials have been developed using biotechnological approaches to the life sciences. There have also been major research advances in the development of new materials derived from fine chemicals as well as in the utilization of new drug delivery systems such as liposome and microcapsules. Transition of early research into product development is vigorously promoted, utilizing research "seeds" and incorporating user requirements, "needs" and "wants". Product development research includes developing formulations for various products and developing appropriate packaging such as containers for the products. Specifications for ingredients, manufacturing method and packaging are perfected by extensive investigation of the four quality characteristics described in Section 4.1 (safety, stability, efficacy and usability) and the application is filed under the Pharmaceutical Affairs Law if application is required. In parallel with this procedure, scaling up (mass-production engineering investigation) from the laboratory scale to the mass-production scale is examined by both the researchers and plant engineers. Mass production and commercialization begin when an application in accordance with the Pharmaceutical Affairs Law has been approved.

6. Scientific background, technology and its future2-4) The development process of cosmetics is described in Section 5. All of the developmental processes are closely linked to many branches of science and technology, much of which is put to practical use in the R&D (Fig. 1).

8 New cosmetic science

Commercialization Plan (Market Research and Fashion Trends, etc.)

Basic and Applied Research and Development

Needs

Seeds Product Design

Organic Chemistry Inorganic Chemistry Pharmacology Analytical Chemistry,—' etc.

(Stability)

Contents Base Formula, Raw Materials Coloring Agents Fragrances Additives

Packaging Materials Glass Bottles Synthetic Resin Containers Metal Container and Tubes Wrapping Paper

pMaterial Science Processing Technology Printing Technology, etc.

.Surface Chemistry—. Microbiology —|

(Usability)

Rheology

(Safety)

Dermatology Biochemistry

—|

(Efficacy)

Physiology Physical chemistry—] Psychology, etc.

(Appeal)

Psychology —iSensory Test, etc.

Formulating & Packaging Research and Testing

Usage Testing

\

Formulation Manufacturing Methods Container Specifications

1

Application under Mass Production Quality Control Technology —| Technology Investigation Pharmaceuticals Statistical Science Affairs Law (if rerquired) Chemical Engineering I—J Manufacturing -Approval -^ Mechanical Engineering, etc. of products

X

Products Fig. 1. Cosmetic development process and related sciences and technologies.

Until about 1970, the main interest of research was upon aspects of the product. The focus was on product stability, fine texture, good after feel, manufacturing technology and quality control. Colloid science, rheology, and statistics were the major areas of research. The first oil crisis in 1973 led to a period of low growth of cosmetics, and compatibility between user and product and the safety of cosmetic products became the primary interests of research. In the 1980s, this trend became more evident. In addition to the problem of safety, product usefulness, that is what the product can do for humans, became the main research goal. In addition to scientific disciplines centered on products, research is increasingly being conducted into a wider range of human-related subjects including dermatology.

Introduction to cosmetic science 9

physiology, biology, biochemistry, pharmacology, etc. Other scientific areas such as psychology, psychoneurology, and immunology are also becoming important in the development of cosmetics. These latter areas are important in investigating the psychological effects of cosmetics on peacefulness, happiness, relaxation, and freedom from stress. It is evident that the development of cosmetics is a human science that combines both the "hardware", or technological aspects of producing a product, and the "software", or physiological and psychological needs of the user. In the future, even more cutting-edge technology will be brought to bear upon the "hardware" aspects of producing products, so that products with even better performance will be developed. From the performance aspect, there will be major advances in the development of biophysiologically useful materials for the face and scalp with innovative functions such as prevention of wrinkles and of hair loss, and the promotion of skin lightening and of hair growth. In addition, physico-chemical high-performance cosmetics will appear that will add new dimensions to the concept of cosmetics. New foundations will be developed; for example, photochromic pigments that will change face color more beautifully according to the variation of light, resulting in a foundation makeup that looks natural under any lighting conditions. At the same time as cosmetics evolve physiologically and physico-chemically, they will also evolve in their psychological effects. Some fragrances stimulate human beings and others calm them, while some makeups improve appearance and thereby can help women recover from depression. In other words, cosmetics are not limited simply to physiological functions, but cosmetics can also have a positive psychological effect and can promote human health and happiness by way of the five human senses which are hearing, smelling, seeing, tasting and touching. In still another dimension, the antidepressive effect of improving appearance is linked to a beneficial effect upon the immune system which has great influence upon one's health. Recent cutting-edge research in psychoneuroimmunology has clarified that cosmetics can indeed play an important role in such protective effects. From this perspective, the categorization does not stop simply with cosmetics. Products with even better pharmaceutical properties (cosmeceuticals) are being developed and even more can be expected in the future. Cosmetic science covers the fields from natural sciences to human and social sciences; it is an important interdisciplinary element in various scientific disciplines. In the future, we can expect even more progress based on our current research and on new discoveries in other scientific fields.

References 1. Asaka, T., Ishikawa, K. ed.: Quality Assurance Guidebook, Union of Japanese Scientists and Engineers Publications, 1974. 2. Ozawa, T.: Fragrance J., 17 (7), 29-32 (1989). 3. Ozawa, T.: Fragrance J., 18 (1), 15-20 (1990). 4. Mitsui, T.: J. Soc. Cosmet. Chem. Jpn., 24 (2), 75-90 (1990).

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Part I

1. Cosmetics and skin 2. Cosmetics and hair and nails 3. Color and cosmetic color materials 4. Cosmetics and fragrances 5. Raw materials of cosmetics 6. Cosmetics and pharmaceutical agents 7. Cosmetics and physical chemistry 8. Stability of cosmetics 9. Preservation of cosmetics 10. Safety of cosmetics 11. Usefulness of cosmetics 12. Cosmetics and containers 13. Aerosol technology in cosmetics 14. Analytical chemistry of cosmetics 15. Cosmetic manufacturing equipment 16. Regulations on cosmetics 17. Cosmetics and information

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1

Cosmetics and skin

1.1. Structure and functions of skin LLL

Skin

Skin covers the entire body and protects it from various types of external stimuli and damage as well as from moisture loss. The surface area of the skin of an adult person is about 1.6 m2. The thickness of skin varies with age, sex and location. Generally, the skin of men is thicker than that of women. However, women have a thicker subcutaneous fat layer. In general, the skin of the eyelids is the thinnest and that of the soles of the foot is the thickest. The outer skin is divided into three layers called the epidermis, the dermis, and the subcutaneous tissue. Various appendages, such as hair, nails, and glands (sweat and sebaceous), are also found in the skin (Fig. 1.1). The epidermis is composed of several cell layers about 0.1-0.3 mm thick. From the external surface inwards, these layers are called the horny layer (stratum corneum), granular layer, spinous layer, and basal layer. The basal layer is formed of a single layer of columnar cells (basal cells) abutting against the basement membrane which is in contact with the dermis. The basal cells divide continuously and, the "daughter cells" move in the surface direction to form the spinous layer. The spinous cells have many intracellular connections called desmosomes. As a result, the cell surfaces appear to have spine-like projections. These cells are separated by a very narrow gap through which nutrient-rich lymph flows freely. The spinous layer is several cell layers deep and is the thickest layer in the epidermis. Above the spinous layer, there are two to three layers of granular cells. The granular cells are named after the keratohyalin granules that they contain, giving them a "granular" appearance. The cells in the outermost horny layer change in a number of ways. A number of organelles including nucleus disappear and the cells are filled with fibrous protein named keratin. The divided basal cells therefore move in sequence to the surface of the epidermis and their form changes as described through a continuous and complex process to produce the biologically and chemically resistant horny layer. It is this horny layer which is in direct contact with cosmetics and which reflects good skin condition. The following section describes how the epidermis changes (keratinization) in more detail. In addition to these keratinizing cells (keratinocytes), the epidermis also contains melanocytes which produce the pigment melanin. The melanocytes are scattered be13

14

New cosmetic science

Hair follicle Horny layer \ (Stratum corneum) (10 to 15//m) Epidermis —--^ 100 to 300//m)

Sebaceous gland Apocrine gland Erector muscle Blood capillary Sweat gland

Horny layer Epidermis

Dermis (2000 to 3000/^m)

Blood capillary Sweat gland

Subcutaneous fat Subcutaneous Capillary Fig. 1.1. Basic structure of skin.

tween the basal cells at the basal layer. The epidermis also contains Langerhans cells with immune response functions as a protective mechanism against invasion of foreign materials. The dermis is composed of connective tissue below the epidermis. The convoluted surface of the dermis is in contact with the epidermis and the areas where the epidermis protrudes downward into the dermis are called epidermal ridges. The areas of the dermis near the epidermal protrusions is called the papillary dermis, and the deeper dermis is called the reticular dermis. Unlike epidermal cells, many of the dermal cells, are not in tight cellular contact with each other, and there are many extracellular spaces. This part of the skin that has a macromolecular network structure is called the extracellular matrix. The dermis also contains mast cells, that produce histamine and serotonin responsible for the immediate allergic response, and fibroblasts, which synthesize and secrete the extracellular matrix. The basic materials comprising the extracellular matrix consist of glycosaminoglycans, or acidic mucopolysaccharides, and fibrous proteins. Glycosaminoglycan has different forms depending on the type of saccharide from which it is formed and depending upon the position of the sulfate group. In skin, however, hyaluronic acid and dermatan sulfate are the most common forms. Glycosaminoglycans exists as proteoglycans, combining protein, and can contain large quantities of water forming a gel. The fibrous proteins are embedded in this gel. The water in the gel transfers nutrients, metabolic products and hormones between the blood vessels and the cell tissues. The fibrous protein is composed of collagen and elastin for constructive purposes as well as fibronectin and laminin for connective purposes. Collagen is the principal protein of the extracellular matrix and maintains the form of the tissues. Elastic fibers are connected to each other, forming crosslinks to maintain tissue elasticity. As a result of this construction, the dermis plays a large role in the elasticity and tension of

Cosmetics and skin 15

the skin. The dermis also contains blood vessels, nerves, hairs, hair-erector muscles, sweat glands, and sebaceous glands. Beneath the dermis, there are subcutaneous tissue which contains many adipose cells in and between the connective tissue. The boundary of the dermis is not very clear. The main role of the subcutaneous fat is to regulate temperature. Subcutaneous fat is generally better developed in women than in men and in children than in adults. 7.7.2.

Keratinization

The most important function of the epidermis is protection against external stimuli such as dehydration, UV light and other physical factors, as well as chemical factors; the outermost layer, or horny layer provides this protection. As described previously, the epidermis is composed of the basal layer, spinous layer, and granular layer. These cells are continually moving towards the outer layers and changing their form to ultimately become the horny layer. This process of cellular change in the epidermal cells is called keratinization or cornification. The horny cells are created continuously, the oldest cells are shed from the outer surface of the skin but they are replaced from below thereby maintaining the thickness of the horny layer. This type of continuous replacement of the cell layer is called "turnover". The turnover varies with the site and age, but in normal skin the turnover rate is believed to be about 4-6 weeks. When the skin is penetrated by a foreign object or the horny layer is damaged, the division of the cell in the basal layer increases in response causing the turnover rate to increase thereby expelling the foreign object and promoting recovery. In addition, repeated chemical or physical stimulation increases the thickness of the horny layer. These responses protect the epidermis from external stimuli. The intracellular changes that comprise keratinization and form the protective horny layer are described below (Fig. 1.2). The basal layer, the lowermost layer of the epidermis forming the cell layer above the basement membrane undergoes cell division. One of the newly-divided cells remains at the basal layer and the other moves towards the outer epidermis, beginning the keratinization process. The cells separating from the basement membrane become the spinous cells. The precursors of the keratin fibers found in the cells of the horny layer are already being synthesized in the cells of the basal layer, but the changes characterizing epidermal keratinization are first seen in the spinous layer. The small bodies called lamellar granules appearing in the spinous cells are the first signs of keratinization. These lamellar granules are full of lipids and are named for their lamellar construction. Immediately before moving to the horny layer, the contents of the granules are discharged outside of the cell. The lamellar construction is maintained, fused with each other and a sheet-like construction spreads between the cells of the horny layer. The principal components of the lamellar granule are lipids such as ceramides, cholesterol and fatty acids. These materials are believed to prevent permeation and diffusion of water-soluble materials, as well as prevent loss of the natural moisturizing factor (NMF) in the horny layer (described below). These materials are also related to intercellular contact between cells of the horny layer^^

16 New cosmetic science

Horny layer

Granular layer

Spinous layer

Basal layer

Fig. 1.2. Structure of epidermis. N, nucleus; LG, lamellar granule; BM, basement membrane, KH, keratohyalin granule; CE, cornified envelope (thickened cell membrane)

The following characteristic changes are observed in the granular layer. First, the cell membrane thickens. Special proteins bind from the inside of the cell to form a thickened cell membrane or cornified envelope and the membrane changes to a completely insoluble, toughened structure by formation of alternate crosslinking by disulfide (S-S) bonds and y glutamyl e lysine bonds. The second change observed in the granular layer is the new appearance of intracellular keratohyalin granules. The main components of these granules are amorphous proteins named filaggrin, which have mutually cohesive functions with keratin fibers in the horny layer. The nucleus and other intracellular organella which have been present to this point disappear suddenly, and most of the water content of the cell is lost so that the internal cell changes dramatically to a compact structure called the "keratin pattern" formed by keratin fibers embedded in filaggrin. It is believed that these changes in the structure contribute to the protective functions of the skin. However, this minute structure soon disappears and only the keratin fibers remain and

Cosmetics and skin 17

the filaggrin is broken down into amino acids. Some of these amino acids are remetabolized. For example, the most abundant amino acid, glutamine is converted to pyrrolidone carboxylic acid which has a high hygroscopicity; the histidine is converted to the natural UV absorber, urocanic acid. These amino acids and their metabolites are the main components of the natural moisturizing factors (NMF) found in the horny layer and play a central role in the hydration (moisture retaining) function of the layer^). This maintenance of optimum moisture levels is very important in keeping the skin supple and beautiful. As a result of the processes described above, the horny layer is believed to be responsible for providing the skin with its protective functions combining flexibility and suppleness. LL3.

Sebaceous glands and sebum

The sebaceous glands are found over the entire body except the palms of the hand and the soles of the feet. The size, form and distribution density differ according to the part of the body. There are large numbers on the face and head averaging about SOO/cm^, while there are relatively few on the four limbs averaging about SO/cm^. The parts with the most sebaceous glands are the scalp, face, chest, center of the back, armpits and pubic area, etc. There is a close correlation between the size of the glands and the amount of secretion. The cells comprising the sebaceous glands change into lipid-producing cells from the undifferentiated basal cell, which finally dies to secrete the lipids. In other words, the cells of the sebaceous glands produce lipid while being repeatedly broken down and rebuilt. The lipids produced by these sebaceous glands are excreted through the sebaceous gland ducts to the skin surface by way of the hair follicle. The lipids excreted from the sebaceous glands in this manner are mixed with other lipids derived from the epidermis. Usually about 0.4-0.05 mg/cm^are present on the skin surface. This mixture is called skin surface lipids, and the composition is shown in Table 1.14).

The skin lipids are believed to have the functions outlined below. In the normal human horny layer, the skin lipids moisturize and keep the horny layer supple to prevent the transepidermal water loss from the skin. The lipids also prevent the entry of harmful substances and bacteria as well as loss of internal body fluids, etc. Table 1.1. Composition of human skin surface lipids Lipid

Average Amount wt%

Range wt%

Triglycerides Diglycerides Fatty acids Squalene Wax esters Cholesterol Cholesterol esters

41.0 2.2 16.4 12.0 25.0 1.4 2.1

19.5—49.4 2.3-4.3 7.9-39.0 10.1-13.9 22.6—29.5 1.2-2.3 1.5-2.6

(Downing, D.T., Strauss, J.S. & Pochi, P.E. : Variability in the chemical composition of human skin surface lipids. J. Invest. Dermatol. 53 * 232, 1969)

18

New cosmetic science

The amount of skin lipids varies with different parts of the body, age, sex, season and skin temperature, and also varies on a daily basis. In human beings, men have more sebaceous glands than women so they produce more skin lipids. In addition, the function of the sebaceous glands in embryo (fetus) and newborn babies is stimulated by the effect of sex hormones received from the mother. These glands subsequently shrink and their function declines during early childhood. They are reactivated at puberty and the function is stimulated by the effect of sex hormones. The functions decline again in old age. In early puberty, young women produce more sebaceous secretions than men, but men produce more later on. After middle age, in women, the functions decrease rapidly after menopause, but men still show relatively high values (Fig. 1.3). The activity of the sebaceous glands is largely affected by hormones. In particular, male hormones cause the sebaceous gland to expand and increase lipid synthesis. At present, there is a strong body of opinion that human sebaceous glands are not under nervous control. The hair erector muscle is smooth muscle and is connected to the hair root and is controlled by the autonomic nervous system. The hair shaft is erected by the contraction of the erector muscle, and the sebum are excreted simultaneously by the compression of the sebaceous gland. 1.1.4. Sweat glands and perspiration The sweat glands secrete perspiration. They are classified into two types: eccrine glands and apocrine glands. The main role of the eccrine gland is to lower the body temperature through evaporation and to suppress sudden increases in body temperature resulting from hot environments and severe exercise. This is called thermal perspiration in contrast to nervous perspiration resulting from psychological stress. In addition, there is also perspiration caused by eating strongly-flavored foods such as spicy seasonings. The average number of eccrine glands is about 2.3 million which can produce more than 1 1 of perspiration per hour and more than 10 1 per day. The eccrine glands are found over the whole body but are most common on the head, forehead, palms and soles of the feet. The eccrine glands are glomal bodies found in the dermis or subcutaneous tissues and open to the skin surface via a duct running through the dermis and epidermis.

0-9

10-19 20-29 30-49 50-59 60-69 Age (years)

Fig. 1.3. Comparison of amounts of sebum between different age groups. Source: Yamamoto, A. et aL\ J. Invest. Dermatol., 89,507 (1987).

Cosmetics and skin 19 Table 1.2. Components of perspiration^^ Substance NaCl Urea Lactic acid Sulphides

Content (g/100 ml)

Substance

Content g/100 ml

0.648—0.987 0.086—0.173 0.034—0.107 0.006—0.025

Ammonia Uric acid Creatinine Amino acids

0.010—0.018 0.0006—0.0015 0.0005—0.002 0.013—0.020

(T. Kuno : Perspiration, Youtokuska, 1946)

Their secretion is slightly acidic and suppresses bacterial activity. The solid content in eccrine perspiration is about 0.3-1.5 wt% and the principal component is NaCl. Other components include urea, lactic acid, sulfides, ammonia, uric acid, creatinine, and amino acids, etc. (Table 1.2). The apocrine glands are limited to some parts of the body with hair (armpits, pubis, testicles, pudendum, and anal areas) and the nipples. Like the sebaceous glands, the apocrine glands are connected to the hair follicles; instead of opening to the skin surface like eccrine glands, they open into the upper part of the hair follicle. Women have more apocrine glands than men. Negroid people have more apocrine glands than Caucasians, and Japanese have fewer apocrine glands than Caucasians. Apocrine glands secrete an extremely complex perspiration because some of the cells are shed and mixed in with the perspiration which, unlike eccrine sweat, includes smell factors and viscous materials. In addition, bacteria on the skin surface convert the organic materials in the perspiration to odorants. Apocrine perspiration is weakly alkaline and bacterial infection occurs easily. Secretion of apocrine perspiration starts at puberty, but there are many unclear points concerning the composition of apocrine perspiration and its physiological function. The eccrine glands are under autonomic control but the apocrine glands are largely affected by hormones and it is not clear whether or not they are controlled by the autonomic nervous system. It is known that the structure of eccrine glands becomes disordered with age, that the secretory cells atrophy and that secretion of perspiration declines. On the other hand, the apocrine glands are not greatly affected by aging.

1.2. Biological functions of skin The skin covers the entire surface of the body and is subject to various direct external stimuli. The skin protects the body from these stimuli and also adapts the activities of the body itself to changes in its surrounding. An adult has a skin surface area of about 1.6 m^ and the skin forms the mucous membranes at the body orifices. The skin is an organ with a variety of important functions. 1.2.L

Protection

The elastic fibers of the dermis and the subcutaneous fatty tissues act to prevent external mechanical shocks from being transmitted directly to the body interior. The skin has an alkali neutralizing capacity and the skin surface is kept at a weakly acidic pH to protect against chemical toxins. Parts of the body receiving chronic mechanical shock such as

20

New cosmetic science

the feet, kneecaps and the hands of manual workers have a thickened horny layer to protect against external stimuli. In addition, the outermost horny layer of the skin and the skin surface lipids act as a barrier against penetration of water and loss of body fluids. They also form a barrier against external toxins. Unsaturated fatty acids in the skin lipids have bactericidal properties and prevent growth of bacteria on the skin. In addition, the skin has immunity-related cells which provide the body with its immunity defense reaction via the immune response. These types of skin response, such as the tuberculin response, provide valuable information about the sensitivity of humans to bacteria. The melanin pigmentation in the skin absorbs and protects the body against harmful UV radiation. In addition, unevenness of the skin surface, horny layer, keratohyalin granule, etc. play a role on diffraction of light to protect the body from harmful light. 1.2.2.

Thermoregulation

The skin adjusts the body temperature by changing the amount of blood flowing through the skin by dilation and constriction of the skin blood capillaries and by the evaporation of perspiration. Both the skin blood capillaries and the eccrine glands are under autonomic control. The body temperature adjustment center is found in the hypothalamus; when the body temperature falls, it increases the activity of skin vasoconstrictor nerves to constrict the blood capillaries and prevent the body temperature falling. When the body temperature rises, the neural activity diminishes, and the blood capillaries dilate to increase heat loss. The sweating center is also in the hypothalamus. In addition, the horny layer, subcutaneous tissues and the body itself prevent swings in body temperature by blocking transmission of changes in external temperature to the body interior. The erector muscle of the hair also plays a thermoregulatory role by trapping an insulating layer of air at the skin surface which reduces loss of body heat. The erector muscle of the hair (goose bumps) is also under control of the autonomic nervous system. 1.2.3. Sensory

perception

The skin senses changes in the external environment and is responsible for the skin sensations. The skin senses pressure, touch, temperature and pain. There are various receptors in the skin for detecting such environmental changes; the Meissner's corpuscles, Merkel discs, Golgi Mazzoni corpuscles are responsible for the sensation of touch. Pacinian corpuscles are thought to be related to the sense of pressure, Krause end bulbs sense cold, Ruffini corpuscles sense temperature, and free nerve endings are related to the sensation of pain. External stimuli stimulate these sensory nerve endings which convey the information via the spinal cord, brain stem and hypothalamus to the cerebral cortex which interprets the sensation. 1.2.4.

Absorption

A variety of substances are absorbed from the skin into the body. There are two absorption paths, one through the epidermis, and one via the sebaceous glands of the hair follicles. Steroids such as female hormones, male hormones and adrenocorticosteroids, as well as fat-soluble materials such as vitamin A, D, E and K are absorbed through the

Cosmetics and skin 21

skin, but water-soluble materials are not easily absorbed as a result of the barrier to water and water-soluble materials formed by the horny layer. The fat solubility of the material to be absorbed, the age of the individual, skin blood supply, skin temperature, water content of the horny layer, degree of damage to the horny layer, and ambient temperature and humidity all play major roles in transdermal absorption. One benefit of this type of transdermal absorption has been the development of cutaneous drug delivery systems as a method for supplying medications to the body. 7.2.5. Other functions The skin also plays a role in indicating emotional state, such as blushing, and fright (paleness and erect hair), and can be described as an organ signaling emotion. The skin also synthesizes vitamin D through the action of UV light on vitamin-D precursors in the skin.

1.3. Color of skin 1.3.1. Skin color Skin color varies with race and between individuals; it also varies with age, geographic location, season and part of the body. In addition, it is affected by health and emotions, including stress. Skin color is generally darker in men than women, and in older than younger people. Some parts of the body such as the palms of the hand and soles of the feet are lightly pigmented, and (in many cases) the scrotum, pubis, perineum and nipples are more pigmented. When viewed externally, the color of the skin surface reflects the pigments it contains, including melanin, melanoid, carotene, oxyhemoglobin and deoxyhemoglobin. In addition, skin color is influenced by various factors such as the thickness and water content of the horny layer, the blood flow, the amount of oxygen in the blood, and the state of the intercellular adhesion of the horny cells. Fig. 1.4 shows the reflectance spectrum. So-called "white" skin shows an absorption curve in the vicinity of 548 and 578 nm, typical of oxyhemoglobin. So-called Japanese "white" skin has very little melanin in the epidermis and the transparency is high, so the effect of blood vascularization is strong and the color is generally perceived as pink. By contrast, "black skin" contains a lot of melanin and the absorption by hemoglobin in the blood is low. Skin color changes with season. When the skin color is plotted in the Mansell coordinates as shown in Fig. 1.5, the hue change from reddish to yellowish (reduced value and increased chroma) towards summer from winter. In comparison to "white" people, the melanin absorption of the skin of Japanese is stronger and the skin color is often described as yellow, but there is a wide dispersion depending on the part of the body (Fig. \.5Y\ Generally, skin color changes with aging, with a tendency to change from reddish to yellowish and reduced value. Moreover, there are clear differences in the hue of different races. For example, the skin color of Japanese is more yellowish when compared to that of Europeans and Americans (Fig. 1.6)9).

22

New cosmetic

science

100 90 80 White complexion

Dark complexion

D^

Q

400

450

5t08

550

600

658

700

Wavelength (nm) Fig. 1.4. Reflectance spectrum of skin (cheek)^^

7.3.2. Skin pigmentation

mechanism

1.3.2.1. Melanin The most important pigment determining skin color in humans is melanin. Melanin is synthesized by the melanosome organelles in the melanocytes. Melanin is transferred to the nearby keratinocytes via the dendrites of the melanocytes. In human skin, melanocytes comprise about 1 in 7 or 8 basal cells in the epidermal basal layer, hair roots and external root sheaths. This density is not thought to vary between different races. Consequently, the racial variation in skin color is caused by the production of melanosomes in

Winter

r^~-'

v^^

Summer i 5

lOR

5YR Hue

3

4 Chroma

Fig. 1.5. Seasonal differences in skin color (cheek)^\

Cosmetics and skin

Chroma

Value

Hue

23

Red OYR lYR 2YR \

3YR

\ •/ / •

4YR 5YR How

^-A 1

1

1

1

1

1

1

10s 20s 30s 40s 50s 60s

10s 20s 30s 40s 50s 60s

Age

Age

Age

1 . 1

lOs 20s 30s 40s 50s 60s

Fig. 1.6. Aging changes in skin color. • , Englishmen; • , Frenchmen; A, Japanese

each melanocyte, by the number of melanosomes transferred to the keratinocyte, and by the degree of maturity and the manner of dispersion of the melanosomes within the keratinocyte. In other words, in the epidermal cells of Caucasians or persons of light skin, melanosomes are found as clumped complexes surrounded by membranes. However, in "colored" races, a darker color is seen because the melanosomes are widely dispersed. The melanin synthetic pathway is believed to be as shown in Fig. 1.7. In this pathway, tyrosine is oxidized to dopa; the next stage is to dopaquinone due to the action of tyrosinase, and then the reaction progresses by autoxidation thought to be accelerated by the enzymes. 1.3.2.2. Carotene Carotene is a carotenoid pigment and is known to exist in three isomers: a, ^, and y. The carotene hydroxyl derivative, xanthophyll, is also a carotenoid pigment. When it is in-

«XK^ N

HO, COOH

Tyrosine

O2

HI

ni N^^COOH H2

Dopa

0=

N

H3

COOH

Dopaquinone

HO HO

H

5,6-dihydroxyindole

COOH H Dopachrome

Melanin Fig. 1.7. Melanin synthesis pathway ^^'^2'^^l Source: Seiji, M., Tomita, Y.: Handbook of Dermatology, 3B, Structure and Function of Skin II, Nakayama Shoten, 1982.

24

New cosmetic science

gested orally, although most is converted to vitamin A by the intestinal mucosa, some carotenoid is absorbed directly into the blood by the gastrointestinal tract without conversion to vitamin A, and it is combined with y8-lipoprotein. Blood carotene is easily deposited in the horny layer where it produces a characteristic yellow color in the thicker parts of the horny layer and subcutaneous tissues, but it is not normally deposited in the mucous membranes. The yellow color of skin is principally due to carotene and is found in more abundance the skin of in men than in women. 1.3.2.3. Hemoglobin Hemoglobin is found in erythrocytes and is composed of four subunits consisting of heme, an iron containing molecule, and globin protein. The iron is also bound to the imidazole of the histidine residue in the globin molecule. The oxygen molecules are bound reversibly and are transported from the lungs to the tissues. Reduced ferrohemoglobin in venous blood gives blood its deep red color. The ferrohemoglobin is combined with four oxygen molecules in the lungs, producing the bright red oxyhemoglobin in arterial blood. The red color of hemoglobin is largely seen in the face such as the chin, and areas where capillaries are close to the skin surface. 1.3,3. Methods for expressing skin color Early simple methods of measuring skin color used comparison between a skin color chart and the appearance of the actual skin but the accuracy of this indirect comparison method was poor, and such methods have largely fallen into disuse. The method used most widely today uses a spectrophotometer, and there are many varieties of handy instruments conforming to the JIS standards. Spectrophotometers measure the apparent skin color and color difference as Y^y (CIE-1931 XYZ tables), L'^a'^b^, and Mansell {H*V*C)\ currently, the Mansell system is most popular. The absorbance of the three primary pigments determining the skin color is measured from the spectrum curve. In other words, there are four bands: the oxyhemoglobin absorption bands at 542 and 576 nm, the carotene band at 482 nm, and the deoxyhemoglobin band at 556 nm. The effect of melanin is observed as the decrease of reflectance at all bands. Color chemistry divides the three main components of color into hue {H), value (V) and chroma ( Q . Table 1.3 shows an example of the measurement of Japanese women's skin.

1.4. Methods for distinguishing skin condition The term "skin condition" is a beautician's term for the condition of skin. The term "normal" as used by the beautician does not necessarily have the same meaning as "normal" when used in the field of dermatology. Even in the dermatologically "normal" skin, there is a variety of different skin conditions. To maintain healthy skin there is a need to precisely determine the skin condition and for careful skin care. This section explains the methods for evaluating skin condition, particularly the best methods for evaluating the skin of healthy people. Basically, there are a number of external non-invasive evaluation methods and this section also explains the classification of skin based on these methods.

Cosmetics and skin 25 Table 1.3. Skin color of Japanese women

Average

Max.

Min.

Range

SD (Standard deviation)

28.4

60

16

-

-

H V C

4.SYR 5.9 3.8

7.2 YR 6.5 4.4

1.0 YR 5.3 3.0

6.2 1.1 1.4

1.25 0.25 0.26

H Under Eyes V C

1.5YR 5.9 4.1

6.2YR 6.6 4.9

7.2YR 5.3 3.2

9.0 1.3 1.7

1.78 0.24 0.32

H V C

4.7YR 6.3 3.7

8.0YR 6.7 4.3

9.9YR 5.8 3.1

8.1 0.9 1.2

1.45 0.21 0.26

Age Forehead

Cheeks

Female residents of Tokyo aged 18 to 60 (n= 500)

1.4.1. Methods for evaluating skin condition 1.4.1.1. Types of skin surface The surface of the skin has a number of fine striations running both horizontally and vertically through it. The valleys are called furrows and the plateaus enclosed by furrows are called ridges. The formation created by these is called the skin surface pattern. The skin surface pattern can be observed in detail by using silicon resin to take a mirrorimage cast (negative replica) of the skin surface which is then magnified. Fig. 1.8 shows a number of replicas of representative cheek skin with differences in regularity and definiteness of skin surface pattern. Externally, a replica of young, healthy, smooth skin has a clear fine skin pattern. Conversely, poor skin which is dry and rough has an undefined pattern, and in extreme cases has no pattern at all. By using this replica method and magnification, it is easy to determine changes in the skin which cannot be seen by external observation alone. As described below, changes observed in the skin surface reflect internal changes in the skin, especially changes in keratinization and changes due to aging. In recent years, these characteristic patterns have been quantified using computer image analysis making replica analysis a very powerful tool in providing an objective understanding of skin surface pattern s^^). 1.4.1.2. Water content of horny layer The horny layer must have a water content of 10%-20% to maintain its normal functions and to sustain a healthy condition of the skin. If the water content of the horny layer falls, the skin looses suppleness and becomes harder, causing cracking and peeling. As mentioned previously, the main factor determining the water content of the horny layer is the NMF, especially amino acids, the production of which is closely related to the keratinization process. There are a number of methods for measuring the water content of the horny layer, but generally the best method measures the high-frequency electrical conductivity (conductance) of the skin surface; a number of easy-to-use instruments are commercially available for such measurements. This method does not measure the ab-

26 New cosmetic science

a

b

c d

Few furrows and ridges Wide ranging keratin peeling Poor skin condition Poorly defined furrows and ridges Keratin peeling in some areas Furrows defined but shape of ridges un- Intermediate condition defined Depined furrows and ridges Beautiful skin Well defined furrows and ridges

Fig. 1.8. Classification of skin surface patterns.

solute water content, but it gives an excellent correlation with the water content of the horny layer when conductance is measured under conditions not causing perspiration. Fig. 1.9a shows the water content of the horny layer of skin from the cheek classified into three groups based on the condition of the skin surface described in the previous section. Skin in poor condition with no or a poorly-defined skin surface pattern has a significantly lower water content^^).

Cosmetics and skin

27

1.4.1.3. Transepidermal water loss (TWL) The horny layer acts as a barrier to loss of water in the skin to the outside, known as transepidermal water loss (TWL), which is different to perspiration secreted from the sweat glands. TWL is generally measured using a device that calculates the value from the gradient of the humidity at the surface of the epidermis. The barrier function of the horny layer is believed to be maintained by the densely packed construction of the horny cells as shown by the "keratin pattern" and by the thickened cell membrane of horny cells, as well as by the intercellular lipids derived from the lamellar granules. As shown in Fig. L9b, skin in poor condition has an elevated TWL, suggesting that the barrier function of the horny layer is defective^^^. (a) (b) Water Content of Horny Layer TWL (Transepidermal Water Loss) 30 r 7h

5^

o U ;3

CO

1 T

a c d b e Skin Surface Pattern Ranking (Classified according to Fig. 1-8)

a c d b e Skin Surface Pattern Ranking (Classified according to Fig. 1-8; (c) Production of Nucleated Horny Cells

(d) PCA%

u

0.

03

Skin Surface Pattern Ranking (Classified according to Fig. 1-8

Skin Surface Pattern Ranking (Classified according to Fig. 1-8

Fig. 1.9. Relationship between skin surface pattern and skin physiological parameters.

28

New cosmetic science

1.4.1.4. Incomplete keratinization Horny cells produced during the normal keratinization process do not have a nucleus. However, imperfectly-formed horny cells with a residual nucleus may be produced by exceedingly high proliferation of epidermis or by abnormally rapid keratinization resulting from causes such as inflammation. This is generally described as parakeratosis. Even healthy skin on the head and face, however, has clusters of nucleated homy cells. As shown in Fig. 1.9c, the frequency of parakeratotic cells of the face increases correspondingly to the increase in facial skin roughness, and that of the scalp skin increases correspondingly to the increase in dandruff. The presence or absence of incomplete keratinization can be determined in detail by performing a skin surface biopsy (SSB) using adhesive tape to peel off the horny layer, and then staining the obtained specimen and examining it under a microscope. As shown in Fig. 9, various data reflecting the condition of keratinization can be obtained from the outer surface of the skin. In addition, there are other parameters of skin condition related to keratinization that can be determined, such as the surface area^^ of the individual horny cell, which is thought to be closely related to the epidermal turnover rate, and amino acid metabolism in the horny layer^^^^ (e.g. metabolism of pyrrolidone carboxylic acid from glutamine - PCA% in Fig. 1.9d). 1.4.2. Classification of skin condition As described in the previous section, the condition of the horny layer is an important element in determining the condition of the skin. The amount of skin lipids is another important characteristic. Skin condition has usually been classified into three types: dry skin, normal skin, and oily skin. It was previously believed that the skin dryness and the oiliness were at opposite ends of the same axis with respect to skin condition. Recently, however, it has become possible to evaluate skin physiological parameters as described above, and it is now recognized that moisture and oiliness are independent elements. Sufficient moisture content of the horny layer is relevant to a healthy horny layer and is the result of normal keratinization. Oiliness of the skin is determined by the activities of the sebaceous glands. There is a clear fundamental difference between these skin factors. In recent years, skin condition has usually been classified into four basic types that are based upon lipid and moisture contents. As shown in Fig. 1.10, skin in which the amount of skin surface lipid ranges from normal to low and the water content is high is called normal skin; skin with a low water content is called rough or dry skin, and skin with a high lipid and water content is called oily skin as in the skin classification system previously used. There is an additional group of dry skin, however, that has a high lipid content and is defined as dry-oily skin. It is extremely important to clearly understand the skin condition when determining the correct course of skin care.

1.5. Acne The correct name for acne is acne vulgaris. Seventy to eighty percent of patients are aged 11-25 years old. A slight degree of acne is typical at puberty, but a serious case can cause unsightly appearance and leaves scarring in many cases even after treatment. In

Cosmetics and skin

29

High water content (moist skin)

Normal skin

Oily skin High lipid content (oily skin)

Low lipid content (non-oily skin)>) Dry skin

Dry-oily skin

Low water content (dry/rough skin) Fig. 1.10. Basic principles of skin classification.

some patients, acne can cause psychological upset, and it can often affect daily and social life. From the cosmetic aspect, fast and appropriate treatment is essential in speeding recovery to normal appearance. 1,5.1. Causes of acne To determine the best treatment for acne, it is essential to understand the causes of acne, which vary from individual to individual. Several causes are interdependent, but there are three principal factors outlined below. 1.5.1.1. Hyperactive sebaceous glands (overactive lipid secretion) The sebaceous glands produce sebum continuously. Sebum is secreted from the sebaceous gland duct and makes its way to the skin surface via the hair follicle pore. Testosterone promotes sebum synthesis and secretion and, consequently the sebaceous glands become extremely active at puberty (age 10-16). In particular, the sebaceous glands of areas such as the face, back and chest become very active and sometimes the balance between the amount of sebum produced and the sebum secretion ability cannot be maintained as a result of the hypersecretion. As a result, the secretion of sebum is disturbed, and sebum blocks the hair follicle resulting in inflammation. In adult males the amount of lipid secreted is usually fixed by the activity of testosterone from the testes, but in females, the amount of luteinizing hormone increases rapidly immediately after ovulation, which stimulates the sebaceous glands and increases sebum secretion, resulting in a sudden worsening of acne before menstruation. 1.5.1.2. Hyperkeratosis (accelerated keratinization) at hair infundibulum Hyperkeratosis occurs easily at the infundibulum of the hair follicle and the resulting thickened horny layer or horny materials obstruct the hair follicle pore, causing comedones. If horny materials block the hair follicle pore or duct of the sebaceous gland, or if it becomes narrowed, the sebum cannot be normally excreted, resulting in an obstruction at the hair infundibulum causing an increase in bacterium acnes. These bacilli produce materials that induce inflammation and stimulate the epidermal cells of the infundibu-

30

New cosmetic science

lum, resulting in further hyperkeratotic change. Since keratinization is promoted by physical stimulation and UV light, acne often becomes suddenly worse after the sufferer has been exposed to excessive sunlight at the seaside or in mountains. In addition, leaving the face unclean can often cause inflammation by allowing blockage of the hair follicle pore. 1.5.1.3. Effect of bacteria When sebum accumulates as a result of either excess secretion or hyperkeratosis at the hair infundibulum, the numbers of acne-causing rod bacteria (bacterium acnes) and the coccal bacteria found in the hair duct and on the skin both increase. The lipases of these bacteria break down the triglycerides in the sebum to form free fatty acids resulting in inflammation. Fig. 1.11 compares the skin surface lipid composition in acne and in normal skin. The skin surface of the person with acne has a high level of free fatty acids and a low level of triglycerides. Free fatty acids affect the skin of the hair infundibulum, and the hair infundibulum is damaged by production of various enzymes resulting in inflammation of the connective tissues surrounding the hair infundibulum. Consequently, although bacteria are not the direct cause of acne, they make slight acne worse and induce pustular acne. Each of the above three factors can cause acne independently, but they can also have a complex interaction making the acne even worse. Additionally, there are other causal factors including genetic factors, food, overwork and stress. 1.5.2. Development and formation of acne As described in the previous section on the causes of acne, overactive secretion of sebum coupled with hyperkeratosis causes the hair pores to become narrowed and blocked, resulting in the early first stage of acne called a comedo (Fig. 1.12b,c). Subsequently, the comedo damages and effects the surrounding tissues resulting in inflammation of the tissues surrounding the opening of the sebaceous gland (Fig. 1.12d). This results in an erythematous (red) papule. If this condition progresses, the horny materials and the sebum blocking the hair infundibulum overflows into the dermis to form a pustule (Fig. 1.12e). When bacteria invade the dermis, leukocytes attack the bacteria to form pus. Pus

Cholesterol Cholesterol esters Squalene

Female acne * (17-23 years) o Normal female (20-27 years)

* 0

A

Free fatty acids

\

Wax esters Triglycerides Diglycerides pp Monoglycerides //

'^^"*^ —

^ITi^^^^

— 1

10

20

30

Z—^^**^

1

40

Fig. 1.11. Skin surface lipid composition.

1

50

1—

60%

Cosmetics and skin 31 Precondition to comedos Horny layer

Horny layer thickening in hair pore

Sebaceous gland Hair follicle

(a)

Comedo formation Blackhead

Whitehead plug*

Inflammation

Plug*

Inflammation

Surface blackened by oxidation

Papule

Pustule

Bacterial increase

(d)

VU

(e)

*plug : Keratin and sebum mixture Fig. 1.12 Types of acne.

accumulates in the dermis to form a large raised painful pustule (Fig. 1.12f). When the large pustule subsequently heals, granulation often occurs and a scar remains. 1.5.3.

Skin care for

acne

When the case of acne is particularly severe, treatment with anti-inflammatory drugs may be required. Considering the development and formation of acne described above, good skin care is extremely important in preventing acne and in helping a person recover from acne. (1) Always keep skin clean (a) Clean face with antibacterial cleanser. (b) Style hair so that it does not directly touch the forehead and face. (c) Keep items such as pillows that touch the face and hair directly clean. (d) Do not touch inflamed skin with the fingers.

32 New cosmetic science

(2)

Use of cosmetics (a) Use non-greasy cosmetics formulated especially for acne containing germicidal agents and that suppress lipid production. (b) If oily foundation is applied too thickly, the fine particles will enter and block the hair pores. (3) Decreasing consumption of fatty, sweet and starchy foods (a) Reduce consumption of fatty foods such as fatty meat, nuts, chocolate, and cocoa. (4) Other Reduce stress such as that associated with overwork, overexercise.

1.6. Ultraviolet light and skin 1.6.1. Ultraviolet light Ultraviolet (UV) light is light at wavelengths shorter than visible light; it is divided (Fig. 1.13) into three regions: UV-C (200-280 nm), UV-B (280-320 nm) and UV-A (320400 nm). The shorter wavelengths in UV light reaching the earth from the sun are absorbed by the ozone layer in the upper atmosphere. The shortest UV wavelengths striking the skin are in the range of 290-300 nm and the energy of the UV-B components is about 1/10 to 1/20 that of the UV-A content. However, with increasing damage to the ozone layer caused by man-made gases like flon (chlorofuorocarbon), the filtering efficiency of the ozone layer is decreasing and there is an increase in the very short wavelengths reaching the skin surface which is believed to be inducing more cases of skin

Not reaching Earth surface ^-

Fig. 1.13. Spectrum of sunlight.

Cosmetics and skin 33

o•

X3

Q;

u

-lr->

U

O

c^

-^ o

O -5 ^

9

10

11

12

13

14

15

16

17

O

18 Time

Fig. 1.14. Hourly variation in amount of UV light. Source: Shiseido Lab., Average for Sunny Day June 1987 in Yokohama.

cancer. A 2% increase in the UV levels caused by a 1% decrease in the ozone layer is estimated to result in a 3% increase in the number of skin cancer cases. The strength and amount of UV light vary greatly according to the geographic position, season and time of day. In other words, the relationship between the position of the sun and the earth, and the weather play a major role. Fig. 1.14 shows the hourly variation (sunny day) in UV light and Table 1.4 shows the seasonal variation^^^. In Japan, the distribution peaks at about 12:00h but about half of the daily amount of UV light is received between 10:00h and 14:00h. The seasonal variation fluctuates widely depending Table 1.4. Amount of UV-A and UV-B in sunlight (1981 Yokohama) Month

UV-B (cal/cmVday)

UV-A (cal/cmVday)

1 2 3 4 5 6 7 8 9 10 11 12

0.55 0.58 1.10 1.69 1.61 1.09 1.64 1.46 1.19 1.01 0.39 0.40

10.93 11.45 17.21 23.13 21.65 16.27 22.87 21.50 14.96 13.22 6.97 47.43

Average

1.05

15.63

Measured using PH-11 M-2 AT Integrating UV Meter

34

New cosmetic

science

Table 1.5. Monthly variation in UV wavelengths (300 to 400 nm) in various Japanese cities

City

Asahikawa

Akita

Matsumoto Yokohama

Osaka

Miyazaki

Naha

43.5°N 112 m

39.4°N 9m

3.2°N 610 m

35.3°N 39 m

34.4°N 23 m

31.6°N 7m

26.rN 35 m

January February March April May June July August September October November December

133.1 268.5 587.7 636.8 748.7 818.0 816.9 698.0 520.0 354.4 173.0 130.5

141.7 254.9 595.9 814.1 913.0 951.4 863.7 937.0 675.2 507.2 275.3 175.3

408.4 511.8 729.8 862.2 1114.2 988.2 877.1 896.4 602.6 561.0 401.6 366.7

308.9 368.1 516.4 691.1 839.5 598.8 661.3 713.1 449.9 431.3 274.8 255.6

342.0 449.4 644.5 804.2 1009.2 912.8 848.3 887.5 564.6 539.2 369.5 311.2

474.7 496.0 647.4 799.7 951.5 871.3 975.9 953.0 646.9 594.1 433.2 441.5

410.6 420.8 615.5 691.3 881.2 872.8 994.7 963.3 741.2 642.1 477.3 385.4

Whole Year

5,886 96%

7,105 116%

8,339 137%

6,109 100%

7,236 118%

8,285 136%

8,076 132%

Latitude Altitude

Average

317.1 355.6 619.6 754.2 922.5 859.0 882.6 884.0 600.1 518.5 343.5 255.2

cal/cmVmonth or year

upon the weather conditions prevailing in an area. Although the amount of UV radiation falls in the June wet season, the seasonal peak is found between May and July, and the lowest of UV radiation is found between December and February. In addition, altitude and latitude have a large effect upon UV radiation. More UV light particularly UV-B, is received at higher altitudes and lower latitudes (Table 1.5). When a person is bathed in UV light, reflection plays a large role in exposure to UV light. The amount of UV light also varies greatly depending on the surface irregularities of the body and skin. The nose, cheeks and lower lip, generally receive the most damaging amounts. The skin has a natural defense mechanism to the UV light. The UV light is scattered Wavelength (nm) 400

500

600 700

Horny Layer Epidermis

Dermis

•^.^P^/ Subcutaneous "o Tissues Fig. 1.15. Skin penetration of different light wavelengths (Herrmann)^^^ Source: Hermann, F. etaL\ Biochemie der Hants, 149, Georg Thieme Verlag, Stuttgart, 1973.

Cosmetics and skin 35 and absorbed by the structure and structural materials of the skin to attenuate the amount reaching the deeper skin layers. Among the components of the skin, melanin produced by the melanocytes in the basal layer shows a very effective UV protective effect. In Caucasians, the amount of melanin is lov^, and there are more cases of skin cancer compared to Japanese with darker skin and other races. This suggests that melanin has a high UV protective function. The amount of UV light that penetrates the skin as a result of these factors varies according to the wavelength. Longer wavelengths penetrate the skin more deeply as shown in Fig. 1.15. 1.6.2. Acute response to ultraviolet light Fig. 1.16 shows the acute changes in skin exposed to UV light. Immediately after bathing in UV light, the skin begins the immediate darkening phase. This immediate darkening is the result of oxidation of pre-existing melanin pigment, but the darkening appears to return to the original color within several hours. This response is initiated by UV-A and visible light. Several hours after exposure to UV light, the skin begins to become red, reaching a peak after 8 and then gradually diminishing. This phase is called sunburn. When exposed to very large amounts of UV light, blisters develop and the skin feels burnt. The wavelength region causing this sunburn is the short wavelength peak in the UV-B band shown in Fig. 1.17. UV light in the 290-300 nm band is 100 times more effective than at 320 nm. When we consider the distribution of wavelengths in sunlight, most sunburn must be caused by the 300-310 nm wavelength band (erythrema production curve). The cells damaged by the UV light produce an inflammatory mediator, expanding the capillaries and resulting in the appearance of sunburn, but further details of the sunburn process are as yet unknown. Anti-inflammatory drugs like aspirin or indomethacin can suppress erythema occurring several hours after UV exposure, suggesting that arachidonic acid metabolism participates in the sunburn process. 3 MED

2 MED

Immediately after exposure (Immediate pigment darkening)

24 hours after exposure (Sunburn)

week after exposure (Sunt an)

Fig. 1.16. Changes in skin exposed to sunlight.

1 MED

36

New cosmetic

science

w ^

250 260 270 280 290 300 310 320 nm Wavelength Fig. 1.17. Erythema curve. A, erythema action spectrum; B, erythema production curve by sunlight (based on erythema curve and spectrum of sunlight).

Approximately 3 days after UV exposure, the skin gradually becomes dark (Fig. 1.16). This delayed darkening, or suntan, is produced by an acceleration of the melanocyte function with the formation of melanin in large amounts and with movement into the keratinocytes. Although this response is initiated after the reddening caused by UVB, large amounts of UV-A have the same effect. Skin that has been suntanned by this mechanism gradually returns to the original color after several months. Simultaneously with this darkening, new skin is regenerated under the damaged skin. The old skin peels off 10-14 days after exposure to the UV light. The acute response to UV light varies among individuals. The minimum erythema dose (MED) is a value used to indicate the acute sensitivity of individuals to UV light. The minimum erythema dose indicates the minimal amount of UV light required to cause redness when a person is bathed in UV light. In other words, individuals with high sensitivity have a low MED since only a small amount of UV light is required to cause skin redness. The erythrema response and darkening also differ with the individual and form a basis for classification of skin type from type I to type VI (Table 1.6). Individuals with type I skin show burns with no tans when first exposed to sunlight for 30Table 1.6. Skin type and sunburn and tanning history Skin Type

Sunburn and Tanning History

I. II. III. IV. V. VI.

Always burns easily \ never tans (sensitive) Always burns easily \ tans minimally (sensitive) Burns moderately ; tans gradually (light brown) (normal) Burns minimally ; always tans well (moderate brown) (normal) Rarely burns ; tans profusely (dark brown) (insensitive) Never burns \ deeply pigmented (insensitive)

Based on first 30 to 45 minutes sun exposure after a winter season of no sun exposure. (Source : Federal Register, 43(166), 38265, 1978)

Cosmetics and skin 37

45 minutes after a winter season of no sun exposure and with no suntan lotion, applied to the skin. Type II skin burns easily but shows minimal tanning. Type III tans always after burning, Type IV skin tans quickly after slight burning, Type V tans with almost no burn, and Type VI tans very rapidly with no burn. Caucasians are usually described as falling in the Type I-IV range. The foregoing describes the response of healthy individuals but some people are oversensitive to UV-B while others are oversensitive to UV-A or visible light which has no acute serious effect on healthy people. These responses are called photosensitivity and the causes are classified into phototoxic response, photoallergy response and photohypersensitivity response. The former responses result from external materials and UV light, while the latter is thought to have various internal causes. In many cases the causes are not clearly known. The phototoxic response can occur in any person applying any one of a number of materials to the skin and then exposing themselves to sunlight. The occasional photoallergy response is related to the immune system response to externally-applied materials and light and generally occurs only in photo-sensitized individuals. Photosensitivity occurs in xeroderma pigmentosum, photoatopia, porphyria, and other conditions such as virally-induced smallpox. 1.6.3. Chronic response to ultraviolet light So-called fisherman's skin and farmer's skin both demonstrate the typical chronic response of skin to UV light. Such skin is dark, feels rough to the touch, and is deeply wrinkled. The nape of the neck, which is constantly exposed to UV light, has characteristic diamond-shaped wrinkles. If this condition worsens, skin cancer may result. Since these types of changes are distinct from natural aging, they are called photoaging or dermatoheliosis. The face is most susceptible to these changes because it is exposed to sunlight throughout the year. It is not clear which wavelength band causes this photoaging, but UV-A, which penetrates deep into the skin as well as UV-B, is believed to contribute to these changes. Since the skin does not show an acute response to UV-A without heavy exposure, UV-A has not been thought to be dangerous. In recent years, however it has been shown that the dangers of UV-A cannot be ignored. Photoaging was first described in Caucasians but it also occurs in the darker skinned races as well and has been clearly confirmed in races living at high altitudes exposed to high UV light levels (Fig. 1.18). People living at high altitudes already show skin wrinkling in their 20s, and the degree is comparable to skin wrinkling in Japanese 4050 year-olds living a normal lifestyle. When these photoaging changes are examined histologically, epidermal thickening and overdeveloped melanocytes are observed. The main components of the dermis are collagen fibers and net-like elastic fibers. Photoaged skin has an abnormal increase in the amount of elastic fibers, and the fine dermal blood capillaries are also dilated. These changes are the opposite of what occurs with true aging changes. It has recently been shown that the immune system is also affected by chronic exposure to UV light. In the future, the effect of UV light on the entire body, and not just the skin, will be clarified.

38 New cosmetic science

Fig. 1.18. Wrinkled skin of high-altitude dweller.

It has recently been reported that application of vitamin A acid to photoaged skin causes the wrinkles to disappear and the skin to return to a youthful condition^^\ 1.6.4. Prevention of exposure to sunshine It is now believed that excess exposure to UV light causes damage to skin and such exposure has almost no benefits. Consequently, the skin should be protected against sunshine to prevent the damage caused by acute and chronic UV exposure. Previously sunscreens were applied to prevent excessive sunburn only during leisure activities. It is now known, however, that dark spots and wrinkles are promoted by chronic UV light exposure, so daily prevention is required. To maintain healthy and beautiful skin, sunscreen should be applied in addition to protective clothing and hats when going out in the sun.

1.7. Aging of skin 1.7.1. Symptoms of aging Like the teeth and eyes, the skin is an organ in which aging changes are easily observed. The degree of change varies greatly between individuals and also depends on the part of the body involved. Table 1.7 lists some of these changes found in dermatological diseases related to aging. However, in addition to these pathological skin changes, a number of other changes occur which detract from the beauty of the skin (Table 1.8). These are called natural or "intrinsic" aging changes to distinguish them from pathological skin changes^^^.

Cosmetics and skin 39 Table 1.7. Dermatological diseases observed in elderly people ' Lentigo senilis ' Leukoderma senile • Verruca senilis ' Angioma senile ' Acrochordon ' Neurofibroma senile (C type nevus) ' Senile comedo ' Senile sebaceous hyperplasia ' Precancerosis (actinic keratosis, cornu cutaneum, Bowen's disease, lentigo maligna) ' Carcinoma cutis (acanthoma, basal cell carcinoma)

L7.2. Instrinsic aging

andphotoaging

The face and nape of the neck as well as back of the hand are frequently exposed to sunlight and become rough and deeply lined. Skin that is continuously exposed to strong sunlight over long periods shows these characteristic changes. Aging signs caused by UV rays are called photoaging. Skin in an elderly person that is unexposed to sunlight, such as the stomach and lower back is quiet different in its internal structure from sunexposed skin in the same person. Generally in intrinsic aging, reduction of many functions and atrophic changes occur in the skin such as reduction of cellular activity and skin thinning. Conversely, photoaged skin is thickened, and there are various symptoms called elastosis that display the presence of massive quantities of thickened, tangled degraded elastic fibers. Table 1.9 shows the characteristic changes in both cases^^'^^^. Both photoaging and intrinsic aging occur in facial skin, but the degree of aging changes that are obvious differs from individual to individual because photoaging is affected by lifestyle, such as the amount of time exposed to sunlight and type of protective daily skin care and intrinsic aging is affected by genetic factors and other internal factors. Table 1.8. Aging signs of skin • Increased wrinkles ' Increased looseness " Reduced gloss, luster, smoothness ' Reduced elasticity • Coarsening of skin texture and random furrows ' Pigmented spots, depigmented spots in some parts of body in some people (The former is called lentigo senilis, the latter is called leucoderma senile.) • Yellowish skin • Thinning of scalp hair and loss of vitality " Reduced scalp hair and body hair ' Increased gray hair ' Lengthening of eyebrow and ear hair ' Coarsening, muddying and bending of nails

40 New cosmetic science Table 1.9. Anatomical differences between intrinsic aging and photoaging "Epidermal Changes> Item

Photoaged Skin

Intrinsic-Aged Skin

Epidermal Thickness

• Thick epidermis

• Thin epidermis

Epidermal Cells (keratinocytes)

• Non-uniform cells • Cells distributed randomly (similar to precancerous condition) • Loss of polarity • Frequent enlargement • Diversified melanosomes (melanosomes lacking cells)

• Uniform cells • Defined cell distribution)

Stratum corneum

• Increased number of cell layers • Diversified form, staining properties and size of corneocytes

• Normal cell layer • Uniform corneocyte size

Melanocytes

• • • • •

• • • • •

Langerhans Cells

Increased cell number Diversified cells Increased melanosome production Marked reduction in cell number Diversified cells

• Polarity maintained • Usually atrophied • Melanosomes uniformly distributed

Cell number reduction Uniform cells Poor melanosome production Slight reduction in cell number Normal cells

(Kligman, A.M. : Aging and Skin, 3. Photoaging of Skin, p.35, Table 2, Seishishoin, 1986) Item

Intrinsic-Aged Skin

Photoaged Skin

Glycosaminoglycans

• Markedly increased

• Slightly decreased

Elastic Tissues

• Tremendous increase • Degenerated into amorphous mass

• Increased but almost normal

Collagen

• Marked decrease of bundles and fibers

• Bundles thick and disoriented

Reticular Dermis Fibroblasts Mast cells Inflammatory cells

• • • •

• • • •

Papillary dermis

• Grenz zone of new collagen (repair zone)

• Non» Grenz zone of new collagen

Capillary vessel

• Small vessels great loss • Abnormal vessels • Telangiectatic

• Moderate loss • Normal • Non-telangiectatic

Lymphatics

• Practically absent

• Moderate loss

Thickened ; Increased and hyperactive Increased Inflammatory cell penetration

Thinner Decreased and inactive Decreased No inflammatory cells

(Kligman, A.M. : Aging and Skin, 3. Photoaging of Skin, p.35, Table 1, Seishishoin, 1986)

1.73. External changes in aged skin 1.7.3.1. Wrinkles Wrinkles occur on almost all parts of the body such as the face, especially the forehead, around the eyes, between the eyes and around the mouth, and on the nape of the neck, elbows, armpits, feet and hands. In most cases, they usually start appearing around age 30 and increase in number, depth and area with aging.

Cosmetics

and skin

41

Fig. 1.19 shows an example of aging changes in wrinkles around the outer corner of the eyes and the results of quantitative analysis using image analysis. Such analysis clearly indicates a marked increase in wrinkles in the late 40s^^'22). Even though we talk about wrinkles as a whole, there are various types of wrinkles, and several classifications have been developed.

a. Aging changes of skin surface configuration at outer corner of eye using direct skin analyzer system.

;c

"

>i I1

/

^

n.sV^ n.s^ 0

10

20

30

40

50

60

70

Age (years) BOX is the number of meshes (obtained by spHtting the binary image into 9 x 9 meshes) where the black pixel ratio is 60% or more and correlates to the amount of wrinkles at the outer corner of the eye. b. Aging changes of skin surface configuration (facial wrinkles) at outer corner of eye. * : p<0.01 (vs 18 to 19 years of age) ns : Not significantly different, Mean value ± S.E. Fig. 1.19. Source: Handbook of Dermatology, 1990-B, Skin Surface Image Analysis, Takahashi, p. 22, Fig. 18, Nakayama Shoten, 1990.

42 New cosmetic science

In one system, the characteristic form of the wrinkles is classified as23'24)(1) Linear wrinkles (commonly called crow's feet around the outer corner of the eye) (2) Glyphic wrinkles (crisscrossing triangular or rectangular wrinkles commonly seen on the cheeks and nape of the neck) (3) Crinkling (fine wrinkles commonly seen on the unexposed skin of elderly people) (1) and (2) reflect photoaging changes, and (3) reflects intrinsic aging changes. The wrinkle formations are caused by various internal and external factors. UV light is known to be one cause, but there are also other causes such as environmental stresses on the skin including dryness, and physical and chemical stress. Wrinkles are thought to be formed by the loss of tension and elasticity through interactions between reduced water content of the stratum corneum, thickening of the stratum corneum, atrophy of the epidermis, change in the amount and quality of dermal collagen and elastic fibers, change in the three-dimensional structure of the dermis and other changes resulting from external and internal factors^^'^^\ 1.7.3.2. Sagging Sagging of the skin starts around 40 years of age and is most common in the chin, eyelids, cheeks and sides of the stomach. The causes of sagging are the same as for wrinkles. There is reduced elasticity of the dermis and reduced support by the subcutaneous adipose tissues. The strength of muscles supporting the skin is also reduced^^'^^^. 1.7.3.3. Pigmentation, and skin color changes The pigmented spots of skin generally increase with age (Fig. ].20)^^\ In addition, as described previously, the visual value of the skin color is reduced, and the hue tends to change from reddish to yellowish. As a result of these changes, skin tends to become darker. These changes are thought to be related to reduced transparency caused by increased pigmentation, reduced secretion of sebum, and thickening and reduced water content of the homy layer due to aging. 15

•

03

^

OS

u

.2 0^

3

1 V->^ •• 1

**** 30

3^ = 0.09A; + 0.07

• • •• •• •• • • •• • 1

70 50 Age (years)

—

90

Fig. 1.20. Aging changes in amount of pigmentation^^\ Source: Arai, K.: J. Soc. Cosmet. Chem. Jpn., 23 (1), 31 (1989).

Cosmetics and skin

43

Mm wmM

....^:

50 30 40 Age (years) a. Depth of Furrows

10

20

10

20

60

--'^4%

70

'2.

CO

o

60 70 50 30 40 50 20 30 40 60 Age (years) Age (years) Regularity of Skin Furrows . Size of Pores Fig. 1.21. Aging changes in surface configuration of cheek skin using replica image analysis^^\ *F < 0.01 (versus 3-9 years), ns., no significant difference, mean value ± SE. Source: Handbook of Dermatology, 1990-B, Skin Surface Image Analysis, Takahashi, p. 17, Nakayama Shoten, 1990.

70

44

New cosmetic science

1.7.3.4. Surface configuration With aging, skin surface relief, which is formed by furrow and ridges, becomes more shallow and also less precise. The direction of the skin furrows becomes irregular, and skin pores tend to become larger (Fig. 1.21)2^'^^). 1.7.4. Aging changes of skin physiological

functions

1.7.4.1. Horny layer (stratum corneum) The most important parameter of horny layer function is the water content which is generally said to decrease with age. Aging changes in the transepidermal water loss (TWL), which is affected by the barrier function of the horny layer, have not been clearly confirmed. In addition, reductions of skin surface lipids and perspiration are a factor in the appearance of dry skin in elderly people^^'^^'^^^ 1.7.4.2. Epidermis Proliferation of epidermal cells is reduced in the epidermis of older individuals. Consequently, the epidermal turnover, or metabolism is reduced. Data regarding epidermal turnover has been obtained without damaging the skin by measuring the size of the corneocytes. As shown in Fig. 1.22, the surface area of the corneocyte of the cheek and forearm increases with age, indicating that the proliferative activity of the epidermal cells (keratinocytes) is reduced. 1.7.4.3. Dermis Just as the proliferative activity of the keratinocytes in the epidermis declines with age, that of the fibroblasts in the dermis also declines with age. Production of collagen, elastin and glycosaminoglycans by the fibroblasts also decline with age. Moreover, since the turnover rate of collagen and other structural proteins is very Cheek

Forearm 1300 h

B 1200 1000

o c
o U

u

llOOh

o

1000 h

3 CO

10s 20s 30s 40s 50s 60s

10s 20s 30s 40s 50s

Age (years)

Age (years)

Fig. 1.22. Aging changes of surface area of corneocytes from the cheek and forearm of female Japanese^\

Cosmetics and skin

45

(/ig/cm^)

100 Cheek — •-Forehead Outer corner of eye -Nose Chin

5

10

15 20

25

30 35 40 '45 50 '55 60 65

Age (years)

Fig. 1.23. Aging changes in amount of sebum on different areas of the face^^\

slow, various degenerative changes such as cross-links occur on these components, which make skin elasticity reduced. Reduced elasticity is thought to be related to the formation of wrinkles. 1.7.4.4. Subcutaneous adipose tissue Aging causes reduction of subcutaneous adipose tissue and tends to become yellow as a result of increased cholesterol levels. The reduction in subcutaneous adipose tissue reduces the ability to withstand physical shock to the skin and is also thought to be a cause of wrinkles and sagging. 1.7.4.5. Amount of skin lipids The amount of sebum declines with age. This is observed more clearly in women than men, and the degree of change with age differs according to the part of the face involved (Fig. 1.23)283).

1.7.4.6. Skin blood flow The blood flow depends on the body part involved, but generally there is reduced flow with aging and reduction in the ability to withstand cold stimulation and UV irradiation^o). 1.7.5. Prevention and treatment of skin aging Since the aging of skin is the accumulated result of numerous small changes over a long period, daily skin care treatment is important to prevent the various forms of damage that can occur in the skin. For example, a primary cause of skin aging is overexposure to UV light and to drying conditions. Such overexposure should be prevented. In addition, it is important to supply the skin with important components for preservation of good skin condition and to prevent the production of damaging elements that increase with

46 New cosmetic science

aging. Beneficial treatments include massage and hot and cold stimulation to increase the flow of blood carrying nutrients to the skin, and appropriate exercise to strengthen the skin musculature. It is important to maintain a good lifestyle to reduce stress and to maintain a youthful spirit and outlook on life. Cosmetics play a useful role in all of these programs.

References 1. Elias, P. M.: Advances in Lipid Research, Academic Press, New York, 1991. 2. Horii, I. et al.\ Normal and abnormal epidermal differentiation, p. 301, Eds. Seiji, M. and Bernstein, I. A.,University of Tokyo Press, 1982. 3. Horii, I.: J. Jpn. Cosmet. Sci. Soc, 15, 245 (1991). 4. Dawning, D. T. et al\ J. Invest. Dermatol., 53, 232 (1969). 5. Yamamoto, A. et al.: J. Invest. Dermatol., 89, 507 (1987). 6. Kuno, T.: Perspiration, Youtokusha, 1946. 7. Saito, T. et al.: Fragrance J., 13 (4), 10-17 (1985). 8. Nakano, M., Munakata, A.: J. Jpn. Soc. Colour Material, 58, 356 (1985). 9. Takahashi, G. et al\ J. Soc. Cosmet. Chem. Jpn., 23, 22 (1989). 10. Seiji, M., Tomita, Y.: Handbook of Dermatology, 3B, Structure and Function of Skin II, Nakayama Shoten, 1982. 11. Kumagaya, H. et al: J. Soc. Cosmet. Chem. Jpn., 19, 9 (1985). 12. Nakayama, Y. et al: Cosmet Dermatol., 1, 197 (1986). 13. Tagami, H. et al: J. Invest. Dermatol., 75, 500 (1980). 14. Koyama, J. et al: J. Soc. Cosmet. Chem., 35, 183 (1984). 15. Fukuda, M. et al: Cutaneous Aging, p. 589, University of Tokyo Press, 1988. 16. Hermann, F. et al: Biochemie der Hauls, 149, Georg Thieme Verlag, Stuttgart, 1973. 17. Weiss, J. S. et al: J. Am. Wed. Assoc, 259, 527 (1988). 18. Handbook of Dermatology, 2B, p. 217, Nakayama Shoten, 1981. 19. Kligman, A. M.: Cutaneous Aging, p. 353, University of Tokyo Press, 1988. 20. KHgman, L. H. et al: Photodermatology, 3, 215 (1986). 21. Takahashi, G.: Handbook of Dermatology, 90-B, p. 13, Nakayama Shoten, 1990. 22. Agache, P. G. et al: Cutaneous Aging, p. 475, University of Tokyo Press, 1988. 23. Kligman, A. M.: Cutaneous Aging, p. 547, University of Tokyo Press, 1988. 24. Kligman, A. M.: Br. J. Dermatol., 113, 37 (1985). 25. Imayama, S.: Handbook of Dermatology, 90-A, p. 14, Nakayama Shoten, 1990. 26. Imayama, S.: Am. J. Pathol., 134, 1019 (1989). 27. Arai, K.: J. Soc. Cosmet. Chem. Jpn., 23 (1), 31 (1989). 28. Kumagai H., et al: J. Soc. Cosmet. Chem. Jpn., 23, 9 (1989). 29. Tagami, H.: Cutaneous Aging, p. 99, University of Tokyo Press, 1988. 30. Ishihara, M.: Cutaneous Aging, p. 167, University of Tokyo Press, 1988.

2 Cosmetics and hair and nails Hair and nails are actually modified epidermal cells so they are called skin appendages along with sweat glands and sebaceous glands. Moreover, they have the same functions as the fur, claws, feathers and hooves of vertebrates and are composed of keratin, the main component of the horny layer in the skin^^. Although keratin can be classified into the soft keratin of the horny layer, and hard keratin of the nails and hair, this classification only reflects the differences in the cystine content; hard keratin has high levels of cystine, whereas soft keratin has low levels^). For this reason, hard keratin is highly resistant to mechanical shock and chemical attack. The organization of the material we call keratin has yet to be fully clarified, but in biochemical terms, it is a proteinaceous material accumulated and made in the epidermal cells of vertebrates. Numerous S-S bonds create a framework between peptide chains resulting in very low solubility^). In histological terms, it is composed of three parts: keratin fibers, interfibrous materials and horny intermembrane materials^).

2.1. Generation of hair Hair is a characteristic feature of all mammals like the mammary glands and covers the entire body. Animal hair has two basic functions: maintenance of the constant body temperature, and use as a sensory organ^^ Hair had these same functions in early humans who were thickly covered with coarse body hair, but, of all the mammals, only in modern man has there been a reduction of coarse body hair which is now limited to the head and a few other restricted areas. However, vellus hair is still found over the entire body. Although coarse body hair is said to have disappeared, the hair remaining on the body of modern humans still has its original functions. Head hair protects the skull and facial bones, eyebrows protect the eyes against perspiration and dust, eyelashes protect the eyes against bright sunshine; nasal hair prevents the passage of dust, insects, etc., into the upper respiratory tract. Most importantly, all hair follicles are richly endowed with sensory receptors and have a highly-developed sense of touch"^). 2,1.1, Generation and types of hair Human hair structures develop between 9 weeks and 4 months after conception^). All the hair structures of the human embryo are formed in sequence from the head down to the caudal part of the body. On the head, the first hair structures are formed in sequence at the eyebrows, top lip and lower chin and then on the scalp and face, and finally on other parts of the head. New hair structures are formed continuously after viviparity and al47

48

New cosmetic science

I—Body hair r-Vellus-T^ . u • . ,, H ir J hair ^ ^ ^ i r changing to terminal hair at puberty „ . , I—Short hair (eyebrows, ears, nose, etc.) •-TermmaH r , . hair ^ ^ o n g hair (head hair, beard, underarm hair, pubic hair) Fig. 2.1. ClassiOcation of hair.

though they develop uniformly in the first period, the difference in the density depends on the growth of the skin as the body develops, and on the body part. This early hair is called lanugo and is extremely fine and short. No new hair structures are formed after birth. The lanugo is lost in the 8th month after viviparity to be replaced by relatively thick vellus hair up to about 2 cm long. The entire human body at birth is covered with vellus hair. This is finally replaced during growth after birth by long thick terminal hair according to the body location. The appearance of terminal hair varies with the age that puberty is reached, body location, and sex^\ With the exception of the palms of the hands, soles of the feet, lips, nipples and mucous membranes of the sex and other organs, hair covers the entire body and the length and thickness depend on the location. This hair is classified into two types: terminal hair, and vellus hair. Terminal hair may be either long or short. Depending on the location, vellus hair changes to terminal hair when puberty is reached^). This classification is shown in Fig. 2.1. As described earlier, the number of hairs in human beings does not increase after birth. Pinkus^^ reported the number of hairs on the heads of women as follows: Blonde 140,000 Brunette 109,000 Black 102,000 Red 88,000 There are many reports estimating the number of head hairs at around 100,000. In addition, the speed at which hair grows depends on the location. Saito et al.^^ reported that the crown head hairs of Japanese men grow at 0.44 mm/day while temporal hairs grow at 0.35 mm/day. On the other hand, Farber et al.^^ reported that the crown head hairs of Caucasian adults grow 0.35 mm/day while beard, underarm hair and eyebrows grow at 0.38, 0.3 and 0.16 mm, respectively. 2.1,2. Composition of hair and the structure of hair follicles Fig. 2.2 shows a cross-section of a hair and hair follicle. The epidermis is invaginated into the dermis to form a tubular pocket called the hair follicle. The sebaceous gland opens directly into the upper part of the follicle; this gland secretes sebum which lubricates and protects the scalp and hair. A smooth muscle called the arrector pili muscle, which is under autonomic control, is connected near the center of the hair follicle and runs at an angle towards the epidermis. It is named after its function of erecting the hair by horripilation when the body senses cold. The part of the hair emerging from the skin surface is called the hair shaft and the part within the skin is called the hair root. The bulbous end of the hair root is called the hair

Cosmetics and hair and nails 49

Hair shaft

Epidermis

Hair follicle

Arrector pili muscle Sebaceous gland

Melanocyte

^ Dermis

Hair root

Blood capillary Hair papilla Fig. 2.2. Structure of hair root (diagram).

bulb. The center of the hair bulb is invaginated to form the dermal papilla which is both vascularized and contains nerves. Nutrients from the food, and oxygen are absorbed by the dermal papilla for generation and growth of hair. The cells of the hair in contact with the dermal papilla are called the hair matrix and are responsible for the actual production of hair. In other words, the hair matrix absorbs nutrients and oxygen from the blood capillary entering the dermal papilla and forms hair by repeated cell division. The hair matrix also contain melanocytes that determine the color of the hair. Fig. 2.3 shows an enlarged model of the hair bulb. The line drawn through the maximal diameter of the hair bulb is called the Auber critical leveP^). This line marks the boundary between the upper and lower halves of the hair bulb. The lower half is called the hair matrix and is composed of rapidly-dividing undifferentiated cells. Most of the cell division within the hair bulb occurs here and almost none occurs in the upper half. The hair matrix cells moving towards the upper half from the critical level of the hair bulb form the shaft of the hair; they grow and divide into the medulla, cortex, cuticle and inner root sheath formed of hair keratin. This process is very similar to the process by which the horny layer of the skin is formed when keratinocytes in the epidermal basal cell layer divide continuously and move out towards the surface of the skin. The epidermal keratinocytes are responsible for normal keratinization and they finally differentiate into keratin cells which are all alike. However, in the process (keratinization) of forming hair, the cells are not all alike; the medulla, the cortex, the cuticle and the inner root sheath differentiate into cells with characteristic morphology and they each have characteristic forms of keratin^ i).

50 New cosmetic science

Medulla Cortex Cuticle Inner root sheath Outer root sheath Auber critical line Hair papilla Hair matrix cell

Fig. 2.3. Enlarged diagram of hair bulb.

The cortex cells migrate gradually upwards, lengthen in a spindle-shaped manner and become keratinized. In addition, the fibers become bundled together to form fiber bundles. The cell nucleus of the keratinized cortex cells remains as a residual nucleus. The cuticle cells form a single layer from the hair matrix to the upper part of the hair bulb and migrate upwards. At about the mid-section of the upper part of the hair bulb, the cuticle cells begin to elongate. Above the upper part of the hair bulb, the longitudinal axis of the cells starts to become inclined perpendicularly to the axis of the hair follicle. When the cells are about l/3rd of the distance up the hair follicle, the outer edge of the cuticle cells changes orientation from horizontal to perpendicular and an overlapping fish-scale pattern of unusually thin cells is formed. The reconstruction of the cuticle cells and the reorientation is completed by the time they reach the mid-section of the hair follicle. At this point, they have lost the cell nucleus and are in direct contact with the cortex cells^). The inner root sheath is formed by the periphery and outer edge of the hair matrix. The inner root sheath is broken down by the time the thinner upper part of the hair follicle is reached, or in other words, near the opening of the sebaceous gland. Its main function is said to be the creation of the form or profile of the hair root in the hair follicle. The cells forming the outer root sheath are very similar in form to the basal cell layer and spinous cells of the epidermis, but there are fine differences so they are probably not formed from the hair matrix. 2.1.3. Hair cycle The hair is different from nails in that it does not grow continuously. The life of each hair is independent of other hairs and they are repeatedly growing, falling out and regrowing. This is called the hair cycle and is shown in Fig. 2.4. The cycle is divided into three parts: anagen (the growth period), catagen (the cessation of growth period), and telogen (the resting period). Hair is only produced in the growth period. During this period, the dermal papilla is large and the hair matrix are dividing actively, so the hair is

Cosmetics and hair and nails

51

Sebaceous gland

C

Hair bulb Hair papilla Hair papilla Early anagen—•Anagen period-•Catagen period-•Telogen period—•Hair loss>. period (5 to 6 years) (2 to 3 weeks) (2 to 3 months) J Fig. 2.4. Hair cycle of head hair shaft.

elongating. In addition, the hair bulb reaches into the sub-dermal tissues. When the growth stops for a time, the hair follicle has reached the catagen period. The catagen is the shortest period and it begins when the melanocytes in the hair bulb stop producing melanin. In the subsequent period, the cell division in the hair matrix decreases and then finally stops. Next, the cells in the major part of the follicle are consumed by surrounding macrophages^^). The hair root shrinks to just below where the arrector pili muscle is attached (1/2 to 1/3 the length of the hair follicle in the growth period) and this marks the beginning of the telogen period. In the telogen period, the dermal papilla forms a ball close to the tip of the hair follicle^^). In the resting period, the next generation of hair starts growing from the base and this naturally pushes the older hair out. Although this is called hair loss, in fact from 70120 hairs (telogen hair) are lost each day. The lengths of each period in the hair cycle are 5-6 years for the anagen period, 2-3 weeks for the catagen period, and 2-3 months for the telogen period^"^).

2.2. Form and composition of hair shaft 2.2.1. Form of hair The form of human hair varies with the racial type; F. Pinkus^^ classified hair into three types: straight, wavy, and curly (Fig. 2.5). However, there is no clear distinction between the three types. In addition, there is a clear difference in form according to location; head hair may be straight while the pubic and underarm hair may be wavy to curly. The thickness of hair depends on the race type, age, and sex (Table 2.1). Japanese generally fall in the range of 0.08-0.15 mm. Thin hair can be from 0.05-0.07 mm while thick hair can be from 0.10-0.15 mm. Generally, thicker hair is coarser and thin hair is finer. The cross-sectional shape of hair can be almost circular, oval or flattened. The ratio of the minor axis of the cross-section to the major axis is called the hair diameter index^^>. An index of 1 indicates perfectly circular hair, while smaller indexes indicate a change in form from oval to flat.

52 New cosmetic science

Straight hair

Wavy hair

Curly hair

Fig. 2.5. Forms of hair.

Hair Diameter Index

Minor Axis of Hair Major Axis of Hair

The index for Japanese hair is 0.75-0.85 or close to round, while that for negro races is 0.50-0.60, nearer to flat. The characteristics for the different races are shown in Fig. 2.115). Table 2.1. Racial variations in hair diameter index Race Type

Hair Diameter .ndex

Negro Eskimo Tibetan Caucasian Japanese

0.5—0.6 0.77 0.88 0.62-0.72 0.75—0.85

2.2.2. Color of hair Natural hair color varies with race type and there is an entire spectrum of colors ranging from black to dark brown to blonde to red. However, this color spectrum is not due to a variety of pigments, but to just two melanin pigments. In other words, the difference between black and red hair is due to the balance in terms of number and size of eumelanin granules, the true melanin responsible for black pigmentation, and phaeomelanin, a sub-melanin responsible for red pigmentation. This balance determines the actual color of the hair^^). Melanin pigment is produced in the branches of the melanocytes in the upper part of the hair matrix of the hair bulb by the production, oxidation and polymerization of tyrosine, an amino acid^^^. The synthesized melanin granules have a spindle-like form (0.8-1.8 //m long and 0.30.4 //m thick) and they are deposited in the cortex cells of the hair, to move upwards as

Cosmetics and hair and nails

53

Table 2.2. Relationship between hair color and melanin pigments Eumelanin

Hair Color

Phaeomelanin

Blonde Red

Large numbers and size Quite large numbers and medium size Few in number and size Almost none

Gray

Almost none

Black Dark Brown

Almost none Very little Some Large number and size Almost none

the hair grows in length^^^ Table 2.2 shows the relationship between the hair color and the melanin pigments. In people with gray hair, especially race types that normally have black hair, it is very clear that the production of melanin by the melanocytes has completely stopped. This is one phenomenon of the aging process. The graying of hair with age usually starts at the sides of the head, progresses to the top of the head until finally the whole head hair becomes gray. 2.2.3. Structure of a hair shaft Fig. 2.6 shows a longitudinal and transverse section through a hair shaft. Moving from the outside to the center, the hair is divided into three layers; the cuticle, cortex and medulla.

Cortex Cuticle

Medulla

Cortex cell

Fig. 2.6. Structure of hair shaft.

54 New cosmetic science

2.2.3.1. Cuticle The cuticle forms the outer surface of the hair and covers the entire hair from the root to the tip. It has an overlapping scale-like structure and encloses the inner cortex. It is composed of translucent, non-pigmented cells. One cell is about 0.5-1.0/^m thick and about 45 //m long^^); cells of normal healthy hair have about 6-8 overlapping cells in close contact. The cuticle comprises about 10-15% of hair^^^ and has a rough surface composed of hard keratin protein; it is quite susceptible to wear and is easily worn off by excessive brushing or strong shampoo. Fig. 2.7 shows the structure of the cuticle at the microscopic level using transmission electron microscopy^^^ From this figure, it can be seen that the cuticle has a number of overlapping plates. In addition, the cuticle can be divided into three layers from the outermost epicuticle, to the exocuticle to the innermost endocuticle^^^. (1) Epicuticle: the epicuticle is about 100 A thick and contains a large amount of cystine. It has the highest resistance to chemicals that dissolve keratin and protein. However, it is susceptible to mechanical wear. (2) Exocuticle: the exocuticle has a layer called the a-layer which is composed of noncrystalline keratin with abundant cystine. It has strong resistance to chemicals that dissolve proteins but it is weak against agents that can break the cystine bonds. (3) Endocuticle: in comparison to the a-layer, the endocuticle has less cystine and al-

Fig. 2.7. Internal structure of cuticle (TEM x 23,000). CMC, cell membrane complex; Ex, exocuticle; En, endocuticle.

Cosmetics and hair and nails 55

though it is strongly resistant to chemicals that dissolve keratin, it is weak against agents that dissolve protein. As shown in Fig. 2.7, the cuticle cell boundary has a section composed of a central black part enclosed by two white lines on both sides. This is called the cell membrane complex {CMCy^\ As can be seen from Fig. 2.8, the CMC is the point where the two cell membranes of adjoining cuticle cells come into contact. It has a three-layer construction^^); the central black layer is called the d-layer and it has a high electron density and is quite thick (about 100 A). The white lines on either side of the d-layer are called the ^-layer and they are believed to be a simple cell membrane including proteins and lipids. In recent years, the importance of these structures has been re-examined and they are believed to play a role in the adhesion between cuticle cells and between cells in the cortex. They are also believed to be important in preventing the loss of cortical water and protein, as well as in forming a path for the transmission of water and chemical agents such as permanent-wave solutions and hair-coloring agents into the cortex. 2.2.3.2. Cortex The keratinized cortical cells on the inner face of the cuticle are a group of cells aligned along the long axis of the hair in a relatively regular manner. They comprise about 85% to 90% of the hair^9\ The long axis of the cells is about 100//m and the diameter is about

^^''^''^:M \

•W0 MF

CMC t% l > - ^ \

i

I nter MF

material

Fig. 2.8. Internal structure of cortex (TEM x 25,000). CMC, cell membrane complex; MF, macrofibril. Source: Maruyama, T., Kanbe, T., Torii, K.: 31st SCCJ Research Seminar, Oral Presentation, 1991.

56 New cosmetic science

1-6 //m. A residual nucleus can be seen in the center of the cell. The cells include melanin pigment granules determining the hair color, which are seen as black oval or circular bodies in Fig. 2.8. The cortical cells are also very important in the physical and chemical qualities related to smoothness and softness of hair. The cortical cells are composed of numerous bundles of fibrous components called macro fibrils (MF) having a spindle-like form with a diameter of 0.1-0.4//m^^^. Fig. 2.8 shows the microstructure of the cortex cells using a transmission electron micrograph^^). The figure clearly shows the cortical cells with the aligned MF bundles as well as the cell membrane complexes, etc., linking neighboring cortical cells. In addition, the figure shows the intermacrofibrillar material filling the spaces between macrofibrils^^^ 2.2.3.3, Medulla The medulla forms the center of the hair shaft and it is composed of honeycomb-like cells with empty spaces aligned along the longitudinal axis of the hair and including melanin. Thick hair may have thick medulla, the cells may appear like continuous pencil lead or they may be broken in places, or there may be no medulla at all as in vellus hair and infant hair.

2.3. Chemical composition of hair 2.3.1. Chemical composition of hair The major components of hair are proteins. The minor components are melanin pigments, lipids, trace elements, and water. 2.3.1.1. Amino acid composition of hair The principal protein component of hair is cystine-rich keratin. Keratin can be composed of about 18 types of amino acids. Table 2.3 shows the comparative composition of human hair, sheep wool and human epidermis^"^). As shown, a characteristic feature of the amino acid composition of hair keratin is the large amount of cystine. In comparison to sheep wool and human epidermis, human hair has about 40-50% more cystine. The ratio of the basic amino acids histidine:lysine:arginine in human hair is 1:3:10 and this ratio is characteristic^). Human hair has this composition for various reasons but there are structural differences; according to Robbins^^^ men have more cystine and there are differences in the amounts of arginine and methionine according to diet. 2.3.1.2. Melanin pigments The melanin pigments in human hair are reported to form less than 3% of the totaP^^. 2.3.1.3. Trace elements The metallic trace elements in hair include copper, zinc, iron, manganese, calcium, and magnesium, etc.^^^ In addition to these metallic elements, there are also reports of inorganic components such as phosphorus and silicon^^).

Cosmetics and hair and nails 57 Table 2.3. Amino add composition of principal keratin (%) Human Hair Keratin

Sheep Wool Keratin

Human Epidermis

Glycine

4.1-4.2

5.2—6.5

6.0

Alanine

2.8

3.4—4.4

-

Valine

5.5

5.0—5.9

4.2

Leucine

6.4

7.6-8.1

(8.3)

Isoleucine

4.8

3.1-4.5

(6.8)

2.4-3.6

3.4—4.0

2.8

Proline

4.3

5.3-8.1

3.2

Serine

16.5

Amino Acid

Phenylalanine

7.4-10.6

7.2—9.5

Threonine

7.0-8.5

6.6-6.7

3.4

Tyrosine

2.2—3.0

4.0—6.4

3.4-5.7

Asparagine

3.9—7.7

6.4—7.3

(6.4-8.1)

Glutamic acid

13.6—14.2

13.1-16.0

(9.1-15.4)

Arginine

8.9-10.8

9.2-10.6

5.9-11.7

Lysine

1.9—3.1

2.8-3.3

3.1-6.9

Hystidine

0.6—1.2

0.7—1.1

0.6-1.8

Tryptophan

0.4-1.3

1.8-2.1

0.5-1.8

16.6—18.0

11.0—13.7

2.3-3.8

0.7-1.0

0.5-0.7

1.0-2.5

Cystine Methionine

(H.P. Lundgren, W.H. Ward : Ultrastructure of Protein Fibre, Academic Press, N.Y., p.39, 1963)

The total amount of these trace elements determined by ashing is reported as being 0.55-0.94%29). 2.3.1.4. Lipids The lipids in hair vary with the individual but they are reported to form 1% to 9% of the Table 2.4. Internal and external lipids of human hair Lipid Squalene Cholesterol esters and wax esters Monoglycerides Diglycerides Triglycerides Free fatty acids Cholesterol Polarized lipids

Koch^^^

Zahn^^^

External

Internal

9.3% 19.9 3.9 1.8 18.1 45.2 1.8

11.2% 6.4 7.7 5.6 13.3 50.2 5.6

-

-

Internal

-% 1.3

—

0.3 0.3 20.7 0.8 76.6

(J. Koch, K. Aitzermuller, et al. : J. Soc. Cosmet. Chem., 33, 317, 1982) (H. Zahn, S. Hilterhaus-bong : Int. J. Cos. Sci., 11, 167, 1989)

58 New cosmetic science

totaP^^ The lipids obtained from hair are the same as those from the skin; they are classified into lipids (external) that reach the hair via the sebaceous glands of the skin, and lipids that occur internally in the hair. According to the results of Koch et al?^\ typically, there is almost no difference in the composition of the internal and external lipids and the main component is free fatty acids; neutral lipids (wax, glyceride, cholesterol and squalene) have been reported as well. According to Zahn et al?^\ the principal component of the internal lipids is polarized lipids. The comparison of the two sets of results is shown in Table 2.4. Lipids are a field of future growing interest. 2.3.1.5. Water Hair can absorb water and the water content depends on the humidity of the surrounding environment. However, in an atmosphere at 25°C and 65% RH, the water content of hair is usually around 12%-13%. 2.3.2. Chemical bonds in hair The various protein molecules comprising the keratin protein of hair are linked by intermolecular force or bonding. These bonds are believed to maintain the nature and form of hair. Fig. 2.9 shows the active groups and various chemical bonds found in hair^^). 2.3.2.1. Salt linkage (-NHs-OOC-) bond This bond is formed by a mutual electrostatic attraction between the positively-charged Polypeptide chain

Polypeptide chain

NH (Salt linkage)

XH(CH2)2-NH;

NH Lysine residues

(Peptide linkage)

(Disulfide linkage)

Aspartic acid residue

CO

^CH(CH2)2-CO-NH-CH-(CH2)4-NH Lysine residue NH Glutamic acid residue CO \. CO NH CH-CH-S-S-CH-CH I Cystine residue I NH CO

c=o-

I

CHR (Hydrogen bond)

-OOC-CH2-CH

I

-H-

-N CHR

-o=c

N-H-

Fig. 2.9. Chemical bonds in hair. Source: Gershon, S. D. et al.i Cosmetics Science and Technology, 2nd edn., p. 178, Wiley-Interscience, New York, 1972.

Cosmetics and hair and nails 59

ammonium ion of the lysine or arginine residues and the negatively-charged carboxylate ion of the asparagine acid residues. The bond strength is strongest when the pH is in the range of 4.5-5.5 (called the isoelectric point). According to dynamic measurements by Speakman, this type of bonding is responsible for about 35% of the strength of the keratin fibers and it is broken by acid or alkali solutions. 2.3.2.2. Peptide bond (-CO-NH-) The -CO-NH- bond formed between the -COOH of the glutamic acid residues and the -NH2 of the lysine residues when H2O is removed, is the strongest bond. 2.3.2.3. Cystine (-CH2S-SCH2-) disulfide bond This bond is characteristic of proteins containing sulfur; it forms a side chain bond not seen in other fibers and is typical of links with keratin. Currently, it is the basic principle by which a permanent wave is set. The cystine bonds in hair keratin are broken by reducing agents; after the hair has been set to the desired wave, the shape is held by rejoining the broken bonds using oxidizing agents (see item 3.4, Hair Care Cosmetics). 2.3.2.4. Hydrogen bond (C=0'"HN) This bond is formed between amide residues and a nearby carboxyl residue. This bond explains why keratin fibers that have been soaked in water extend more easily than in the dry condition. Conversely, it is well known that when wet hair is curled and then dried, the curls remain in the hair. This phenomenon is called a "water wave".

2.4. Physical characteristics of hair 2.4.1. Extensibility of hair When hair is pulled gradually under a heavy load, it stretches while becoming thinner and then finally breaks when it can extend no more. The extensibility is expressed as the elongation percentage and the load at which the hair breaks is expressed as the tensile strength. The extensibility of hair is measured by stretching a hair of known length at a constant speed in water or under a constant humidity and measuring the load at the break point. The extensibility of hair is not a function of the outer surface but is clearly a function of the hair fiber bundles and is thought to be due to the characteristics of the cortex rather than the cuticle. In other words, the polypeptide chain of the keratin forming the hair fiber bundles is normally in the form of an a-helix but it becomes extended into a zig-zag /3-keratin form; the length of the zig-zag ^-keratin form is about twice that of the a-helix. When the tension is released, the polypeptide chain returns to its normal length^"^) (Fig. 2.10). This can also occur while the hair is extended.

60

New cosmetic science

r I

i

NH

CO

CHR

X®

CO

NH

NH

NH

CHR RHC

Shrinkage/ CHR Water Loss CO

,C0®

OC

CHR

Extension/Water CO Absorption

NH

NH

CHR NH

CO CHR

CO NH

NH CHR

CHR

>

NH CHR /^ /?-form

-form

Fig. 2.10. Transition between a-form and^-form of hair keratin. Source: Elliot, A.: Textile Res. J., 22, 783 (1952).

2.42.

Moisture absorption of hair

When hair is exposed to air, it either absorbs or loses water until it reaches an equilibrium. This equilibrium is affected by the relative humidity. Table 2.5 shows the water content of hair at various relative humidities^^). When the relative humidity is high, the water content of hair also increases. Drooping hairstyles on wet days is due to the breakdown of hydrogen bonds in hair when water absorbed by the hair exceeds a fixed point and the hair returns to the previous style. In addition, brushing on cold dry days generates static electricity and the hairs stick to the brush due to drying out. Hair is very sensitive to changes in humidity; when the moisture content is too high, the hair body and hold is lost and when the level is too low, the hair becomes dry and brittle. Stam et al.^^\ measured the relationship between the changes in the length and diameter of hair and the relative humidity using a microscope and calculated the crosssectional area and the volume from the results (Table 2.6). The results showed that when the relative humidity is high, the length only increases slightly but there is a quite large increase in the diameter. Table 2.5. Water content of hair at various relative humidities Relative Humidity (%) Water Content(%) Temperature : 74 F

29.2

40.3

50.0

65.0

70.3

6.0

7.6

9.8

12.8

13.6

(J.B. Speakman : Nature, 132, 930, 1993)

Cosmetics and hair and nails 61 Table 2.6. Changes in hair diameter and length with relative humidity Absorption RH(%)

0 10 40 60 90 100

Increase in Volume

(%)

Increase in Cross Section Area(%)

0 0.56 1.29 1.53 1.72 1.86

0 4.7 10.5 14.-3 22.3 29.7

0 5.7 12.2 16.3 24.6 32.1

Increase in Diameter

Increase in Length

(%) 0 2.3 5.1 6.9 10.6 13.9

(%)

(R. Stam et al. : Textile Res. J., 22, 448, 1952)

2.5. Hair damage 2.5.L

Condition of hair damage

The hair shaft is the part of the hair protruding from the scalp and it is continually changing according to the age and length of the hair. Additionally, before it is cut, it is subjected to processes such as shampooing, blow drying, brushing, permanent waving, hair coloring and other forms of hair care. It is subject to the greatest environmental stresses including dry atmospheres, UV light, sea water, and swimming-pool chlorine, etc. In particular, the cuticle of the hair shaft is directly affected by these stresses resulting in several cumulative types of damage. Fig. 2.11 shows four examples of the degree of damage sustained by the cuticle. In healthy hair, the edges of the cuticle cells are smooth and the patterns of the cuticle are regular. By contrast, in slightly-damaged hair, part of the cuticle edge is either peeling off or is lost. In damaged hair, the cuticle edge is missing and in some parts, the peeling and loss progresses to another layer. This type of hair has no luster due to random scattering of the reflected light, and the hair does not feel smooth. When the damage has progressed further, in badly-damaged hair, the cuticle is almost completely missing and the cortex is exposed. This type of hair splits and breaks easily. The final result of this accumulated damage is many split and broken hairs (Fig. 2.12). 2.5,2. Hair damage and its causes As a result of damage, hair becomes dry and brittle and loses its body and hold, springiness and lustre; it becomes difficult to style and will not hold a style. The color changes to reddish and there are many split and broken ends. The original beauty of the hair is lost and various problems occur. Table 2.7 summarizes the various reasons for this damage.

62

New cosmetic science

a. Healthy Hair

C. Damaged Hair

b. Slightly-Damaged Hair

d. Badly-Damaged Hair

Fig. 2.11. Degrees of hair damage.

Beauty treatments such as permanent-wave treatments and hair coloring are another chemical cause of hair damage. These chemicals pass through the cell membrane complex (CMC) between the cuticle cells and spread via the CMC of the cortex into the center of the hair. They are known to dissolve part of the CMC20'32), and the proteins inside the hair^^-^^). The cortex plays a role in maintaining the water content of the hair but this function is lost as a result of the dissolution of the CMC and internal proteins. Consequently, damaged hair is very easily affected by changes in environmental humidity causing problems such as dryness and inability to hold a hairstyle.

Cosmetics and hair and nails

63

Furthermore, there are other causes of damage such as UV light and hot air from blow dryers. UV light lowers the tensile strength of hair by generating cysteic acid which breaks the disulfide bonds in hair in the presence of water^^^^\ At the same time, the hair becomes reddish and this is believed to be due to the oxidative breakdown of eumelanin in the hair by the UV light^^^-^^^. Damage and color changes such as reddening are commonly associated with marine and pool sports, but actually, UV light plays the major role in this type of damage which is accelerated by the sea water and pool water. Hair is easily damaged by heat as a result of denaturation of the proteins comprising

Split Hair (xl50)

Magnification of Split Hair (x800)

Broken Hair (x800) Fig. 2.12. Split and broken hair.

64

New cosmetic science

Table 2.7. Causes of damage to hair

• Chemical : Permanent wave, hair coloring, etc. • Environmental : UV light, dry atmosphere, heating with dryer, etc. • Physical : Over-brushing, blow-drying soaking-wet hair

the major part of hair, and excessive use of a hair dryer damages hair. The normal water content of hair is 10-15% but this is reduced through evaporation caused by heating and the hair becomes dry and rough to the touch. At temperatures above 80°C, the hair proteins are denatured and the cuticle is peeled off the hair if it is brushed at the same time as being blow-dried at very high temperatures^^l Caution is required when using a blower for long periods and it is important that the hair is cared for with cosmetic hair treatments before blow drying. Finally, there are physical causes of damage to hair such as over-enthusiastic brushing and blow-drying while the hair is still soaking wet. This always results in loss of the cuticle. Shampooing is a necessary part of daily life, but the friction caused between hairs results in the cuticle peeling off as a result of its inability to withstand wear. Additionally, if the hair is blow-dried while still soaking wet (blown dry while brushing), since the cortex swells with water easily while the cuticle does not, unnecessary force is applied to the cuticle which peels off. Consequently, it is best to towel dry the hair first before blow drying and then to blow dry after the hair is almost dry. The ultrasonic method is a fast way of determining how easily the cuticle is peeled Qff44) Comparison of permanent-waved hair, heat-treated hair, hair exposed to UV light, and untreated hair shows that each of the treatments increases cuticle loss. These results are shown in Table 2.7 which indicates the ease with which cuticle is peeled off in relation to the cause of the damage. From this information, it is clear that after hair treatments such as permanent waving and hair coloring, or after swimming, the hair should be washed in mild shampoo, rinsed and then treated with a hair treatment. 2,5.3. Split hair The final stage of cumulative damage to the hair shaft results in the occurrence of split hairs shown in Fig. 2.12. Hair at this stage has almost no cuticle. Fig. 2.13 shows the changes in the number of cuticle sheets at every 10 cm from the root of a 30-cm hair from a female, observed with a scanning electron microscope. As the micrographs clearly show, at the root, there are 7 overlapping sheets of cuticle cells and there is no difference from healthy hair. However, there is a progressive decrease in the number of sheets at each 10 cm, and at the end of the hair, there is no cuticle. Since hair grows about 1 cm per month (see Section 2.1.1), it is believed that the various physical, chemical and environmental stresses require about 2.5-3 years to completely remove all the cuticle. This type of splitting and cuticle loss to 2 or less sheets of cuticle cells is though to be caused by physical shock including brushing and shampooing.

Cosmetics and hair and nails

Cuticle shee

0 cm Hair Root

7 Sheets

10 cm

4 Sheets

20 cm

1 Sheet

30 cm Hair end

0 Sheets

Fig. 2.13. Hair cuticle loss from root to end in split hair (change in number of cuticle sheets).

65

66

New cosmetic science

2.6. Function and structure of nails 2.(5.7. Function and physiology of nails Nails are a very tough sheet of keratin growing from the epidermis of the dorsal surface of the toes and fingers. They are another form of skin appendage. Nails protect the distal tips of the fingers and toes, enable the fingers to grasp very fine objects, increase the sensitivity of the digits'^^^ as well as increase the strength of the fingers and toes. In addition, the condition of the nails also reflects the health of the body"^^^. In healthy individuals, nails grow by about 0.1-0.15 mm per day'^^^ The growth rate varies with the individual, being faster in children and young people, and slower in older people"^^). The growth rate is also different between toes and fingers, with finger nails growing faster than toe nails'*^^ There are also seasonal growth differences with faster growth in summer and slower growth in winter^^^. 2,6.2. Structure and composition of nails Fig. 2.14 shows the structure of nails"*^^. What is generally called the nail, is actually the nail plate. The nail is equivalent to the horny layer of the skin; it has no living cells, is composed of very tough keratin and is formed of closely-linked sheets of keratin cells. Figs. 2.15 and 2.16 show scanning electron micrographs of the outer surface and crosssection of the nail and the layered structure is clearly evident'^'^).

Nail root Plan

Nail wall Free margin of nail Nail plate

Cross Section-=

Nail bed

Nail matrix Fig. 2.14. Structure of a nail. Source: Higashi, T.: Nails, Nihon Shoseki, 1980.

Cosmetics and hair and nails

67

Fig. 2.15. Scanning electron micrograph of the outer nail surface.

In comparison to the horny layer of the skin, the nail has a lower lipid content of 0.15-0.75%4^\ On the other hand, the sulfur content of 3% is relatively higher than that of the skin keratin^^). Although the form of the nails is different from that of hair, since the proteins from which this is composed are the same, the amino acids in nails are very similar to those of hair in comparison to the horny layer of the epidermis"^^^. Like hair, the nail is produced by the nail matrix. The nail grows out over the nail bed towards the fingertip. (Outer Surface)

;3 CO

Fig. 2.16. Scanning electron micrograph of nail cross-section.

68

New cosmetic science

The nail bed supplies water to the nail and plays a role in ensuring that the nail grows along the nail wall (described below) in a fixed direction. The nail separates from the nail bed at the free margin of the nail and since water is no longer supplied from the bed to the nail at this point, the water content falls, explaining why the free margin of the nail is easily broken^^'^^^. The milky-white half-moon shape at the root of the nail is called the lunula. The nail at this part is not fully keratinized. In comparison to other parts of the nail plate, the lunula is softer and is not in complete contact with the nail bed. The parts of the skin surrounding the nail are called the nail wall. The root of the nail is called the back nail and the sides are called the side nail walls. The skin touching the nail at the root of the nail is called the eponychium; its role is to protect the imperfectly-formed nail. When the eponychium is missing, the nail is often scarred and the newly-formed nail shows abnormalities. The nail matrix contains melanocytes which produce melanin pigment and there are small amounts of melanin in the nail"^^). 2.6.3, Physical characteristics of nails Nails contain from 5% to 24% water depending on the external environment. Like hair, they absorb and lose water quite easily. When nails absorb water, they swell in volume and the thickness changes more than the length and width. This is believed to be the result of the layered construction seen in Fig. 2.16. The change in the toughness caused by water absorption and loss is the same as that of hair becoming softer with water absorption and brittle with water loss. The tendency for nails to break easily is the result of our daily lifestyle such as bathing and washing each day. 2.6.4. Nail damage Nail damage is very common; split nails in which the free margin of the nail looks like mica is called onychoschisis. One cause of split nails at the free margin is the reduced water content due to the inability of the nail bed in this area to supply water to the nail. Another physical cause is excessive use of nail enamel and enamel remover, which cause water and lipid loss, as well as lipid loss due to exposure to soap and detergents. Consequently, when using nail enamel and remover, it is important to choose products that take lipid and water loss from the nail into consideration and to use nail treatments as part of the daily care routine.

References 1. 2. 3. 4.

Noda, H.: Protein Chemistry 4, Structure and Function, (1), p. 763, Kyoritsu Shuppan, 1981. Ogawa, H.: Nishinihon J. Dermatol., 42 (3), 455 (1980). Kobori, T.: Pathology of Hair, p. 107, Bunkodo, 1987. Kobori, T.: Pathology of Hair, p. 15, Bunkodo, 1987.

Cosmetics and hair and nails 69 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50.

Pinkus, H.: The Biology of Hair Growth, p. 15, Academic Press, New York, 1959. Price, M. L., Griffiths, W. A. D.: Clin. Exp. Dermatol., 10, 87 (1985). Pinkus, F.: Jadassohns Handbuch der Haut Geschl. krht, 1/1, p. 239, Springer Verlag, BerUn, 1927. Saitoh, M., Uzuka, M., Sakamoto, M., Kobori, T.: Advances in Biology of Skin, Vol. IX, p. 183, Pergamon Press, Oxford, 1969. Farber, E., Lobitz, W.: Annu. Rev. Physiol., 14, 519 (1952). Auber, L.: Trans. R. Soc. Edinburgh, 62, 191 (1952). Hashimoto, J.: Clin. Dermatol., 27 (1), 15 (1973). Parrakal, P.: J. Ultrastruct Res., 29, 210 (1969). Ito, M., Hashimoto, K.: J. Invest. Dermatol, 79, 392 (1982). Falco, O.-B.: Semin. Dermatol., 4 (1), 40 (1985). Sudo, T.: Diagnosis and Treatment of Hair, p. 11, Bunshodo, 1970. Rock, A., Dauber, R.: Diseases of the Hair and Scalp, 2nd edn., Blackwell Scientific Oxford, 1991. Prota, G., Thompson, R. H.: Endeavour, 35, 32 (1976). Montagna, W., Parakkal, P.: The Structure and Function of Skin, 3rd. edn.. Academic Press, New York, 1974. Mercer, E. H.: Keratin and Keratinization, p. 266, Pergamon Press, Oxford, 1961. Maruyama, T., Kanbe, T., Torii, K.: 31st SCCJ Research Seminar, Oral Presentation, 1991. Leon, N. H.: J. Soc. Cosmet. Chemists, 23, 427 (1972). Swift, J. A., Bews, B.: J. Soc. Cosmet. Chemists, 25, 355 (1974). Swift, J. A., Holmes, A. W.: Textile Res. J., 35, 1014 (1965). Lundgren, H. P., Hard, W. H.: Ultrastructure of Protein Fibre, p. 39. Academic Press, New York, 1963. Robbins, C. R.: Text. Res. J., 891 (1970). Menkart, J., Wolfram, L. J., Mao, I.: J. Soc. Cosmet. Chem., 17, 769 (1966). Bate, L. C. et al:. New Zealand J. Sci., 9 (3), 559 (1966). Goldbulm, R., Derby, S.: J. Invest. Dermatol., 20, 13 (1953). Dutcher, T. F., Rothman, S.: J. Invest. Dermatol., 17, 65 (1951). Nicolaides, N., Foster, R. C : J. Am. Oil Chem. Soc, 33, 404 (1956). Koch, J., Aitzetmuller, K. et al: J. Soc. Cosmet. Chem., 33, 317 (1982). Zahn, H., Hilterhaus-bong, S.: Int. J. Cosmet. Sci., 11, 167 (1989). Gershon, S. D. et al: Cosmetics Science and Technology, p. 178, Wiley-Interscience, New York, 1972. Elliot, A.: Textile Res. J., 22, 783 (1952). Speakman, J. B.: Nature, 132, 930 (1933). Stam, R. et al: Textile Res. J., 22, 448 (1952). Baba, N., Nakayama, Y., Nozaki, F., Tamura, T.: J. Hygienic Chem., 19, 47 (1973). Oku, M., Nishimura, H., Kanehisa, H.: J. Soc. Cosmet. Chem. Jpn., 21 (3), 204 (1987). Kanedaka, S., Miyata, M., Nakamura, Y.: J. Soc. Cosmet. Chem. Jpn., 24 (1), 5 (1990). Beyak, R. et al: J. Soc. Cosmet. Chem., 22, 667 (1971). Robbins, C , Kelly, C : Textile Res. J., 40, 891 (1970). Tatsuda, M., Uemura, M., Torii, K., Matsuoka, M.: J. Soc. Cosmet. Chem. Jpn., 21 (1), 43 (1987). Chedekel, M. R., Post, P. W., Deibei, R. M., Kalus, M.: Photochem. Photobiol., 26, 651 (1977). Kanbe, T., Fukuchi, Y., Uemura, M., Torii, K.: JCSS 14th Scientific Seminar (1989). Higashi, T.: Nails, Nihon Shoseki, 1980. Higashi, T.: Fragrance J., 79, 12 (1986). Yamazaki, I., Tanaka, M., J. Soc. Cosmet. Chem. Jpn., 25 (1), 33 (1991). Yasuda, T.: Fragrance J., 79, 12 (1986). Baden ,H. P.: Biochem. Biophys. Acta, 322, 269 (1973). Nishiyama, S.: Fragrance J., 79, 4 (1986).

3 Color and cosmetic color materials There is a close relationship between cosmetics and color. The search for beauty is a basic human instinct. Makeup cosmetics beautify the appearance by changing the color of the skin. In addition, color can enhance the appeal of cosmetic products which rely on color for image. The rapid developments in the science of color and in instruments for measuring color have made color management much easier, and are now utilized in the design manufacturing and marketing of cosmetics. Year-by-year, the regulations governing the materials used to give cosmetics their color become stricter and stricter from the safety aspect and, in each country, the use of organic color materials in cosmetics is regulated by law with regard to product quality and scope of usage. Powder materials such as inorganic pigments and extender pigments may only be used if they meet the standards of different countries for heavy metals and other impurities or are those which have received the approval of the regulatory authorities. The technical expertise and knowledge of color scientists handling the basic constituents of cosmetics as well as accurate information related to coloring materials used in cosmetics is absolutely essential to this. Additionally, the laws related to coloring materials differ according to national legislation making it necessary to exercise caution when exporting cosmetics.

3.1. Color 3.1.1. Light and color Light enters the eyes when they are open except when there is no light. The component of light that can be seen by the eyes is called visible light. The wavelengths longer than visible light are the infra-red wavelengths and the wavelengths shorter than the visible band are the ultra-violet wavelengths. The wavelength of visible light is in the band 400760 nm (Fig. 3.1). Natural sunlight contains many of the visible wavelengths but it is perceived by the human eye as colorless. However, when sunlight is passed through a prism, it is split into six basic colors: red, orange, yellow, green, blue, and violet. Color is an expression of the different energy levels in light but it is not in itself a property of light. The light wavelengths are sensed by the visual receptors in the eye and the stimulation caused by each wavelength is expressed as color. In other words, color can be described as a sense. 70

Color and cosmetic color materials

71

Visible light -

Ultraviolet light

^

tj o

QJ ;3

>

cCT3

>^

O

CQ

400

Infrared

QJ

QJ CD

500

-a cu

O

1

Cr:::

600

700 wave length (nm)

Fig. 3.1. Wavelength and color.

3,1.2. Color perception Color perception differs greatly in different animals. In this book, we are only describing the human perception of color. The structure of the human eyeball resembles that of a camera. The crystalline lens has a variable focal length and is able to focus the image of an object on the retina. The iris in front of the lens functions like the aperture of a camera. The retina is composed of two types of visual receptors: rods, and cones. The rods function at low light levels and their main role is to sense the intensity of the light, whereas the cones function at high light levels and their role is to sense color. The dashed line in Fig. 3.2 shows the sensitivity of rods which is greatest around 511 nm (wavelength equivalent to yellowish-green). By contrast, the solid line shows the sensitivity of the cones which is greatest at 554 nm (wavelength equivalent to greenish yellow^). In addition, the cones have three types of receptors for blue, green and red. The light absorbed by the rods and cones composing the receptors in the eye is converted to electrical signals which are transferred to the brain via the horizontal cells, optic nerves and spinal cord, where they are interpreted as color and brightness.

>. "5o

1.0

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0.8

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,

1 \

X\

\

\ \ \

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500 600 Wavelength (nm)

\ \ \

X 700

Fig. 3.2. Spectral response curve of scotopic vision (dashed line) and photopic vision (solid line).

72 New cosmetic science

500 600 wave length (mm)

700

Fig. 3.3. Spectral reflection curve, red: Lake red CAB; yellow: Hanza yellow; blue: Phthalocyanine blue.

3,13,

Color of coloring materials

The color of materials varies according to its composition and the type of light striking it. The same material will appear to be a different color in sunlight, fluorescent lamp and incandescent lamp. Light striking an object is either reflected off the surface of the object, back from the object interior, absorbed by the object or passed through the object. When white light strikes a colored object, the wavelength of light observed as the color is reflected and other parts are absorbed. The spectral reflection curve (Fig. 3.3) shows the reflected components of light at each wavelength in comparison with a standard object (white). The form of this curve predicts which color the object will appear. Similarly, the spectral transmission curve shows approximately which wavelengths are transmitted when white light strikes an object that transmits light. Coloring materials are chemical substances that absorb or transmit specific wavelengths. Red pigments reflect red light and absorb light other than red. In addition, red dyes absorb light other than red and transmit red light. 3.1.4, Three attributes of color Color can be classified as either (1) achromatic, or colors such as white, gray, and black which neither absorb nor reflect the components of light, and (2) chromatic, or colors with hue. Chromatic colors have color as a result of absorbing part of the illuminating light or reflecting or transmitting the light in the visible light region. Color is composed of three elements: hue, value and chroma, called the three attributes of color. (1) Hue: Colors such as red, yellow, green, blue and violet demonstrate this quality which is determined by wavelength.

Color and cosmetic color materials

73

White

Green

Chroma

Yellow

Black Fig. 3.4. Three-dimensional color space showing three attributes of color.

(2)

Value: The value is measured on a scale which evaluates whether the reflection from the surface of the object is high or low. When the value is high, the color is bright, and when it is low, the color is dark. (3) Chroma: Chroma expresses the degree of brilliance of color. A brilliant color has a high chroma value and a dull color has a low chroma value. A diagrammatic representation of hue, value and chroma on three axes is called a three-dimensional color space (Fig. 3.4) and any color can be represented in spatial terms within this color space. 3.1.5. Expression of color The human eye is able to recognize several million colors based on slight differences in the value, hue and chroma. When talking about a specific color or when recording a color, we need to be able to define that color exactly. The most accurate way is to have an actual color sample, but even in this case, there is the problem of aging-associated color changes. Ignoring color samples, for any product, it is of importance to be able to manufacture with identical color and there is a need for a systematic method of recording color as a numeric value and classifying it. 3.1.5.1. Color naming methods Trivial names: this is a system of naming colors such as salmon pink, emerald green, and lavender purple created by people who deal with colors frequently. It is called the trivial naming system. A feature of the system is that it is very similar to the original sense of color possessed by people but unless you are a specialist, it is very difficult to get an ex-

74 New cosmetic science

act impression of what color is meant. The system is influenced by the individual variation in people's color sense. General color names: general color names such as red, yellowish-red, yellow, yellowish green, green, bluish green, blue, bluish violet, violet, reddish violet are adjective modifiers related to the value and chroma of color and when used with words such as light, dark, heavy, bright, etc., they can be useful in giving a more detailed impression of color. This object color naming system is described in the Japan Industrial Standards^^ 3.1.5.2. Color systems Munsell color system: the Munsell color system is a system expressing colors in terms of hue, value and chroma. It is a system in widespread use today as it is very similar to the human color sense. In Japan, the Munsell color system has been published by the Japan Standard Association as the JIS Reference Colors^^ As shown in Fig. 3.5, hue is linked in a circle of five principal colors: red (R), yellow (Y), green (G), blue (B) and purple (P) with the addition of five intermediate colors: yellowish-red (YR), greenish-yellow (GR), bluish-green (BG), bluish-purple (BP) and reddish-purple (PR). These ten hues are divided into 10 equal parts in sensory terms and the representative hues are arranged at the 5 positions. This type of circle of colors is called a hue circle. The value is also split into 10 equal parts in sensory terms with the achromatic colors black equal to 0, and white equal to 10. Chroma is assigned sequential values 1, 2, 3,... in sensory terms with achromatic colors being 0. The Munsell color system uses this type of arrangement to express any color in terms of HV/C. For example, 5R4/14 expresses the highest saturation of red. CIE standard colorimetric system: in 1931, the Commission Internationale del'Eclariage established an international system of expressing colors using tristimulus values: X, Y, and Z. In Japan, the XYZ system of describing colors is also incorporated in the JIS^). The CIE chromaticity diagram has two axes, x and y, at a right angle on which the spectral at each wavelength is plotted showing the spectral curve and these are joined up to obtain the spectral locus (Fig. 3.6). The chroma axis is found from the following equations. x = X/{X+Y-\-Z),

y=Y/(X+Y+Z),

z = Z/(X+Y + Z)

Since x + >^ + z = 1, the chromaticity can be expressed just by x and y. The projection of the line linking the achromatic point (W) and the chromatic point (50 in the chromaticity diagram (Fig. 3.6) indicates the principal wavelength Xd at the point (^2) where it intersects the spectral curve; the distance from W is the color "purity" (same meaning as chroma). Moreover, since Yis equivalent to value, 7, x, y expresses the color. Hunter Lab system^): in 1948, R. S. Hunter proposed a color system with the ability to distinguish colors based on human senses. In this system, the tristimulus values X, Y, and Z are converted to the equivalent L, a, and b values using the following formulae.

Color and cosmetic color materials

75

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Chroma — -^ Fig. 3.5. Munsell Color System (Japan Standards Association, JIS Reference of Color Committee) JIS.

76 New cosmetic science

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()
In addition, the color difference AE between (Lj, a^, bx) and (L2, ^2, ^2) can be found from the following formula. AE= / T L , - L J ^ + ( " a ; ^ ^ i J ^ ( b , ~ b i F L* a* /?* system: the correct name for this system is the CIE 1976 (L* a* &*) Color System. This system is based on the use of tristimulus values XQ, FQ ^^^ ^o correction for perfect white (reference) light reflection corresponding to X, Y and Z of the measuring light reflection. This system is used as substitute for the Lab color system.

Color and cosmetic color materials

11

3.1.6. Color images and impression of color combinations Every color creates various psychological impressions in the person seeing the color and these impressions vary between individuals. However, many people share the same images of different colors and understanding these images is important in designing makeup products and is an important element in the actual effectiveness of makeup. 3.1.6.1. Warm and cool colors Warm colors are colors giving a feeling of warmth and are close to red in the hue circle and include reddish-purple, red, orange, and yellow. They are the colors of the sun and fire creating an image of warmth and heat. Cool colors are colors giving a feeling of coldness and are close to blue in the hue circle such as bluish green, blue, and bluish purple. They are colors of running water and clear lakes creating an impression of freshness, cold and intelligence. 3.1.6.2. Color and emotion Every color creates a different emotional response which may be either quite strong or relatively weak. Typical responses include pleasure, sadness, anger, security, grief and loneliness. Table 3.1. Relationship between color and emotion Attribute

Passion, Anger, Joy, Action, Excitement

Yellowish Red

Fun, Frolic, Liveliness, Health

Yellow

Merriment, Health

Green

Calmness, Relaxation, Calm, Freshness

Violet

Solemnity, Grace, Mystery, Anxiety, Kindness

Blue green

Restful, Coolness, Melancholy

Blue

Calmness and composure. Loneliness, Sorrow, Profundity, Tranquillity

Blue violet

Mystery, Sublimity, Solitude

Cheerfulness Brightness

White

Purity, Truth

Intermediate

Calmness

Gray

Calmness, Depression

Dull

Dullness Heaviness

Black

Gloominess, Insecurity, Sternness

High

Freshness Lively

Bitter orange

Ardor, Violence, Passion

Intermediate

Relaxation Mildness

Pink

Loveliness, Kindness

Low

Stringency Calmness

Brown

Calmness

Intermediate Colors

Middle Calm Ordinary

Cool Colors

Cold Passiveness Tranquillity

Bright CU

03

s o

u

Example of Emotion

Red

Warm, Positive Warm Colors Active

>

Color

Emotion

Cheerfulness,

Pleasure,

Activity,

(Japan Color Science Association : New Color Science Handbook, Tokyo University Press, 1980)

78 New cosmetic science

Table 3.1 gives some concrete examples of which colors elicit which emotional response^). 3.1.6.3. Impression of color combinations Although we have reported that primary colors each elicit an individual emotion, a gradient of two or more colors can elicit a variety of emotions depending on the color combination and this is extremely important in makeup coordination. The effect of color gradation can be used to make the appearance more beautiful when used in combination with the three attributes of color, and forms the basis for the balance between contrast and coordination of color. To maintain balance, hue, value and chroma are all important, but it is essential to give consideration to hue sequence exhibited in the spectral. In the three attributes of the color system, the greatest weight is given to value contrast and hue contrast, but chroma contrast is relatively weak in comparison. Table 3.2 shows examples of the combination images of two colors. 3.1.7. Makeup colors Makeup is said to be a type of art in which a number of colors are applied to the face like on a canvas. In general, women say the main purpose of using makeup is to make themselves more beautiful. Makeup is used on the bare face to create the person's ideal of beauty in harmony with other parts of the body. Consequently, makeup cosmetics are available in a variety of color tones.

Table 3.2. Examples of color combination images Color Combination Color Combination of Same Hue

Combination Hues

of

Similar

Combination of Contrasting Hues (Comi3limentary Hue/ Contrasting Hue)

Combination of Achromatic and Chromatic Colors

1

•

1

Images Within the same hue, a Calm, high elegant, quiet, combination of different light values and chromas

Combination of colors in Harmony, safe, adaptable same segment of hue circle

Combination of Colors at Bright, light, gaudy, active Opposite Side of Hue Circle

Combination of white, gray, black, and chromatic colors Individuality, straightness such as red and blue

Color and cosmetic color materials 79 3.1.7.1. Foundation colors and its applied skin color'^^ The color of bare skin varies according to the race and health of the individual and also changes with season. The color of skin is mainly determined by the combined effect of the absorption of light by melanin and hemoglobin in the skin, and by transmission of light through the epidermis. For more details refer to Section 1.3. In addition, the face is different from a canvas and has location-dependent tone differences; the forehead has a relatively low value, the cheeks have a relatively high value, and under the eyes is slightly reddish. In the case of Japan, Fig. 3.7 shows the relationship between skin color distribution of Japanese women and the foundation color distribution of the Japanese market. The foundation color distribution is wider than the skin color distribution. Therefore, a wide variety of products are available to customers. Since skin color changes between winter and summer, in summer it is best to use foundation colors with a lower value. In addition, a more natural three-dimensional appearance can be achieved by combining colors with slightly higher and lower values than the skin color. The color of skin to which foundation has been applied is a mixture of the color of the bare skin and the foundation and is different from the color of the foundation meaning that care is necessary. The main cause of the difference between the color on the skin and that of the foundation is largely due to the covering effect of foundation, the application method and the amount applied. Fig. 3.8 shows how the same skin appears to have various colors depending on the application condition (thin and thick) of an oil-based foundation; it is not a simple additive mixing of foundation color and skin color but rather skin color approaches the foundation color according to the complex curves shown in Fig. 3.8.

>

o o o O cm o

o

oo

o

o o o o o o oo ODO o o o 00 o o ^ - —

\

O

o Oye O O . 'b O 0 odo o o ooo o 1 o ^o o o ooo 0 1 .'o o o^ o/ / o o oo o O 0 OD O oo o oo oo o / ' / oo OCX) oo o / o / O O O O y oo oo /0 / /' o o o ooo ' o o oo / / o o o /o ' o o oooo ^ o 1 o o /OO o o 10 O oo O 00

0 o

O

°\

O O

/ ' I I

Skin color distribution I 0

V

o

o q& o o

lOR

1

o

o 1

Q

O

\

\ oooooo o \ ooo o ^^ o oooo o opco oooo O O »0 O O 00 \ O O

oo 00 \ao O O

\

\ \

1

000

O

o o joo oaoovo oo o d o oo o ooo o'

l»,

o\o o \^

jo ofo

Skin color distribution

^-<»oo 1 o

o o

'

,

°°o

\ O O / O 00 O K ^ ^ ^ ^ o o •^ o o o O 0 00 O 0 o o

I '

I

/ °

/

O

o oo o ooo o oo

5YR Hue

o 1_

1

1

lOYR

3

4 5 Chroma

6

Fig. 3.7. Color distribution of commercial foundations (in Japan).

80

New cosmetic science

> 7

No.9

T3 C O

Thin application ^ Medium application r "c Thick application J < Sample foundation color

Chroma Fig. 3.8. Relationship between bare skin, made-up skin and appearance of foundation color (for nine test samples, Nos. 1-9.).

When choosing the foundation color, it is important to not only just look at the surface color, but to also apply the foundation to the skin. Foundation for adjusting the color of skin mostly uses so-called "green control" for suppressing the red tones of the human face. This has the effect of creating a natural and translucent quality by reducing the hue and increasing the value using color blending. In addition, green control also largely prevents changes in color with different light sources due to the absorption characteristics of the green pigment. Green is mostly used but blue has largely the same effect. However, aged skin with yellowish tones tends to have reduced value but this can be adjusted using pink colors. In other words, pink works by making yellowish skin tones closer to red and by increasing the value and reducing the chroma. Other control colors include orange, yellow, and purple etc. 3.1.7.2. Color of lips and lipstick color^^ The color of lipstick along with rouge for the cheeks plays an important role in creating a healthy face color. Lipstick is available in many colors but the color of lipstick-painted lips varies with the individual. Lips are much less keratinized and the skin is relatively thinner than ordinary skin and there is no melanin pigment, so the blood capillaries can be seen, making the lips appear red. Fig. 3.9 shows the lip spectral reflectance curve. Panels A and B clearly show the spectral absorbance at 548 and 578 nm compared to the spectral absorbance of skin. However, in unhealthy lip color, like panels C and D, there is almost no absorbance at these wavelengths and the spectrum pattern is very different from the normal patterns of A and B. Panel C indicates that the lips will not show the lipstick color even if applied, and panel D is typical of lips with low chroma as a result of poor blood supply. People

Color and cosmetic color materials 81 90 80 70

A

60

in

/^^^

50

-

40

-

B_^

30 20

/ /y^^ 1 If

•^;;^^^^^^D ^\^ J

10 400

500

600

700

wave length (nm)

Fig. 3.9. Spectral reflectance of lip color (panels A-D). with these types of lips should apply a base coat with good covering power before applying their favorite lipstick to ensure that the required color is seen. Commercial lipsticks have a hue range from lOPR to 5YR, a value ranging from 2 to 6, and a chroma range from 3.5 to 17. However, the basic hue range is 2.5R to 5.OR and the hue of colors appearing each season changes very little, unlike the value and chroma. Among cosmetics, the color of lipstick is most susceptible to seasonal changes in fashion. Every cosmetic manufacturer now launches a promotion campaign each season for new colors. 3AJ. 3. Color of point makeup Nail enamel and eye shadow have become very popular with young women. Consequently, some time ago, point makeup changed from the use of single colors at one location to total coordination based on harmonizing the colors of all the cosmetics used. Similarly, eye shadow tended to be centered on cool colors, and as its name suggests was mainly used to create the impression of a shadow. However, the spread of color TV has changed Japanese fashion sense creating increased demand for purple and green eye shadow with high chroma values. Currently, the term "eye color" is being used more and more to describe eye shadow and many more eye colors are appearing on the market.

3.2. Color materials Color materials mixed with cosmetics must have color and covering power. Large amounts are mixed in makeup cosmetics and the principal function is to cover the skin to the appropriate degree and provide an attractive coloring. In other words, coloring mate-

82

New cosmetic science

rials are used to hide liver spots and other blemishes and to produce a beautiful color creating the impression of health and attractiveness. 3.2.L

Classification of color materials

Coloring materials mixed in with cosmetics can be broadly classified into organic color materials, natural colors and inorganic pigments (Fig. 3.10). Moreover, recent progress in synthesis technologies has permitted more widespread use of perlescent pigments and polymer powders. In addition, powders with various new functions have been developed and are being used in cosmetics. However, all these color materials must still meet the strict safety criteria required for use in cosmetics. 3.2.2. Organic synthetic coloring agents^-^^^ Each nation has its own regulations concerning cosmetic coloring agents. Therefore, particular attention must be paid to each countries prospective regulations. In Japan, organic synthetic coloring agents that may legally be used in pharmaceuticals and cosmetics are divided into three categories. These colors are called permitted colors. Group I: These colors (11 types) may be used in all pharmaceuticals, quasi-drug and cosmetics. Group II: These colors (47 types) may be used in pharmaceutical drugs for external use, quasi-drug for external use and cosmetics. Group III: These colors (25 types) may be used in pharmaceuticals for external use, in quasi-drugs for external use and cosmetics except those used on mucous membranes. The total of groups I, II and III is 83 colors. In the USA, only coloring agents that have received permission from the Food & Drug Administration (FDA) can be used in food, pharmaceuticals and cosmetics. The symbols used in front of the number of the permitted color, have the following meanings.

Organic synthetic coloring agents (Tar colors)

Dyes Lakes Organic pigments

Natural colors Cosmetic coloring agents

Extender pigments Inorganic pigments

Coloring pigments White pigments

Perlescent pigments Polymer powders New functional pigments Fig. 3.10. Classification of cosmetic color materials.

Color and cosmetic color materials

83

-

FD&C: Permitted for use in food, pharmaceuticals, and cosmetics D&C: Permitted for use in pharmaceuticals and cosmetics Ext.D&C: Permitted for use in pharmaceuticals for external use and cosmetics for external use. However, in the USA, the entire list of colors was re-examined using various tests over time, and in January 1990, a new list of permitted coloring agents was announced in which 35 colors are split into the following three categories. (1) Colors permitted for internal and external use (2) Colors permitted only for internal use (not for cosmetics) (3) Colors permitted only for external use In the USA, permission has not been granted for use of organic coloring agents around the eyes. This is a major difference between the USA, Japan and the EU. In addition, in the USA, every batch of coloring agent used in commercial products must have received certification from the FDA (certified color). The number of colors permitted for use in the EU is greater than in Japan and the USA and the usage controls are based on the following four categoriesi^^. (1) Colors which may be used in all cosmetics (2) Colors which may be used in all cosmetics except cosmetics applied around the eyes (3) Colors which may be used in cosmetics that do not come into contact with mucous membranes (4) Colors that may be used in cosmetics that only come into contact with the skin for a short period (such as shampoos) Organic synthetic coloring agents can be divided into three basic groups: dyes, lakes, and pigments and the composition of typical structures is described below.

3.2.2.1. Dyes Dyes are compounds that are soluble in solvents such as water, oils and alcohols and impart color according to the solubility in the cosmetic base. There are two types of dyes: water soluble, and oil soluble. Water-soluble dyes have a hydrophilic group such as sulfonate in the molecule. Azo dyes: The majority of permitted dyes are in this group. They are characterized by the azo-group chromophore (-N=N-) and sodium sulfonate (1). Some dyes without sodium sulfonate are also oil soluble (2). CH3 OH

(1) Sunset yellow FCF

(2) Ponceau SX

Water-soluble dyes are used as coloring agents in lotion, milky lotion and shampoos, etc. Oil-soluble dyes are used in cosmetics such as hair oils.

84

New cosmetic science

Xanthene dyes: Xanthene dyes are divided into acidic and basic types. These types are tautomeric under the action of acids and alkalis (3) and (4).

Br

Br

Acid

^

Alkali

'

U

KJ

(4) Lactone Type (Tetrabromofluorescein)

(3) Quinoid Type (Eosin YS)

The quinoid type are soluble in water and have glowing colors, but are more often used as lakes than dyes, as described below. A typical example is Floxine B, etc. The lactone type dyes are soluble in oil and they dye the skin so they are often used as dyes in lipsticks. Typical examples of this type are tetrachlorotetrabromofluorescein (Deep Red), tetrabromofluorescein (Bluish Red) and dibromofluorescein in the orange group. An example of the basic type is Rhodamin B; they have high chrominance, excellent coloring power, and good durability against sunlight so they are widely used in lotions and shampoos.

(QHs) 2 N . ^ ^ r \ ^ 0 . . ^ ^ ^ \ ^ N (QHs) 3CI

(5) Rhodamine B

Quinoline dyes: Typical examples of permitted colors in this group are the oil-soluble Quinolone Yellow SS and the water-soluble Quinolone Yellow WS with sodium sulfonate.

a:><^ (6) Quinoline yellow SS

a:

(7) Quinoline yellow WS

Triphenylmethane dyes: Dyes with the triphenylmethyl group (8) are extremely soluble in water because they have two or more sodium sulfonate groups. Triphenylmethane dyes are available in green, blue, and violet hues and are used as coloring agents in many

Color and cosmetic color materials

85

lotions and shampoos. Most of them have low light tolerance so it is necessary to check their stability before using them. C3H5

C.

SOsNa

C2H5 N-CH2

^TX SOaNa

-SO3

(8) Brilliant blue FCF

Anthraquinone dyes: When sodium sulfonate is introduced into a compound containing an anthraquinone nucleus, Alizanine cyanine green F (9), a water soluble dye, is produced; when there is no sulfonate, the result is oil-soluble Quinizarin green SS (10) and Alizurol purple. These dyes have excellent light tolerance and the water-soluble types are used in lotions and shampoos, while the oil-soluble types are used in hair products.

(9) Alizanine cyanine green F

Quinizarin green SS

Other dyes: Other typical dyes are Indigo carmine in the indigo group, Naphthol yellow in the nitro group, Pyranine cone, in the pyrene group, and Naphthol green B in the nitroso group. 3.2.2.2. Lakes One type of lakes are insoluble metallic salts of water-soluble dyes such as Lithol rubine BCA which is the calcium salt of Lithol rubine B. They are all called lake pigments and typical examples are Lake red CBA, Lithol red CA, Lithol red BA, Lithol red SR, and Deep maroon. OH H3O

<-

'X

VN=NSOaNa

COOH

\_

(11) Lithol rubine B

}

l/2CaCl2

H3C

T-

\ //

Lithol rubine BCA

86

New cosmetic science

The other type of lakes are materials that have been made by reacting high-solubility dyes such as Sunset yellow FCF (1), and Eosin YS (3) with insoluble salts of aluminum or zirconium to adsorb the alumina or zirconia; they are called dye lakes. The uses for lake pigments and dye lakes are not strictly separated and both are used along with pigments in lipsticks, rouge and nail enamels, etc. Lakes cannot really be separated from pigments and they are both commonly referred to by the general term "pigments". Generally, in comparison to pigments, lakes are characterized by poor acid and alkali endurance and are almost insoluble in water meaning that stability must be tested properly. 3.2.2.3. Organic pigments Organic pigments do not have a soluble group in their structure and they are colored powders that are insoluble in water, oils and other solvents. Permitted organic pigments are broadly classified into azo-type pigments (13), indigo (thio-indigo)-type pigments (14), and phthalocyanine type pigments (15).

vAy . 9'

^N

\-Aj

\\

C-N

N-C

X \ / X

N^

Cu

N

er^V^'\^^c,

( J %/ \,5

(14) Helindone pink CN

(15) Phthalocyanine blue

Generally, in comparison to lakes, pigments have better coloring power and light tolerance and they are widely used in lipsticks, blushers, and other makeup products. 3.2.3. Natural colors Natural colors are obtained from plants and animals, as well as from microorganisms. In comparison to synthetic colors, they have poorer coloring power, and lower light and chemical tolerance; also supplies of the raw materials are unstable so they have not been used widely. However, these natural colors have been used widely in food for long periods. Consequently, they are recently being reconsidered for use based on their safety and pharmacological effectiveness. Looking at the structure, yellow, orange and red belong to the carotenoid group and are mainly found in carrots, tomatoes, red salmon, shrimps, and crab. The yellow, red and purple colors found in hibiscus, grape skins and safflower belong to the flavonoid group. Cochineal, etc., from the cochineal bug belongs to the quinone group. The classification of the main natural colors is shown in Table 3.3. The following section explains the principle natural colors and their actual uses in cosmetics.

Color and cosmetic color materials 87 Table 3.3. Classification of natural colors^^ Group

Sub-group

y5-Carotene /?-apo-8-carotinal Capsantin Lycopene Bixin Crocin Canthaxanthin

Yellow-orange Yellow-orange Orange-red Orange-red Yellow-orange Yellow Red

Carrots Oranges Paprika Tomato Annatto Gardenia Mushrooms

Anthocyanidin

Shisonin Raphanin Enocyanin

Purple-red Red Purple-red

Beefsteak plant Turnips Grapes

Chalcones

Carthamin Safflor yellow

Red Yellow

Safflower(Carthamus tinctorius L.)

Flavonols

Rutin Quercetin

Yellow Yellow

Soba or buckwheat Black oak bark

Flavones

Cacao color

Brown

Cacao bean

Lipoflavin

Yellow

Yeast

Carotenoids

Flavonoids

Source

Color

Material

Flavins

Anthraquinones

Orange-red/purple Laccaic acid Carmine acid (cochi- Blue-red neal) Kermesic acid Orange-red/purple

Scale bug Cochineal bug (cactus) Cochineal bug(Kermes or Japanese oak) Western madder

Alizarine

Orange

Shikonin Alkannin

Purple Dark red

Echinochrome

Yellow

Shikon R o o t s of p u r p l e plants (Alkanna) Sea urchins

Porphyrines

Chlorophyll Hemoglobin

Green Dark red-brown

Green leaves Blood

Diketones

Curcumine (Turmeric)

Yellow

Curcuma longa L.

Betacyanidine

Betanin

Red

Beet

Quinones

Naphthoquinones

(Kokichi Hikime : Handbook, Nikko Chemicals (Ltd.) 585, 1977)

3.2.3.1. ^-Carotene /^-Carotene is a yellow color that was first extracted from carrots but is now known to exist in many plants and animals. It is obtained by extraction from plant materials, fermentation, and synthesis from )3-ionon. It occurs in both cis and trans forms but natural /3-carotene is found in the trans form. The chemical structure is shown in (16) below. It is involved in the efficacy of vitamin A. It is easily broken down at acidic pH and is easily affected by metallic ions. It is used as coloring in milky lotions and creams, etc., and as coloring in foods like butter and margarine.

New cosmetic science

CH3

CH3

CH3

CH CH3

(16)

3.2.3.2. Carthamin This color is extracted from safflower flowers. Safflower (Carthamus tinctorius L.) is an annual in the chrysanthemum family. It originates from India and China and is well known in Yamagata Prefecture in Japan. It has long been used for rouge as a red pigment in East Asia. The structure of carthamin has been published several times, but each time there has been a mistake. However, in 1982, structure (17) below was announced as being correct^^). The color is a deep red and it is used in lipstick and rouge.

^^^^^"^^-0 OH HO o^CeHnOs HO^^'X ^ o HO > < ^ 0 H HO /

CH-V^C- CH-CH

^HC-HC-C

0

0

II

OH

(17)

3.2.3.3. Cochineal, carminic acid This deep red color which is obtained from the dried powdered bodies of the cochineal bug {Coccus cacti L.), which lives on cactus, has long been used in lipstick in the west. The main component is carminic acid (18), a member of the anthraquinone group. At pH 5 or less, it is a reddish orange; at pH 5 to 6, a red to reddish purple, and at pH 7 and above, reddish purple to purple. The color change is reversible by changing the pH. It is used in red-type perlescent pigments and lipstick, etc.

CH3 O

OH (18)

OH HOOC

O

OH

3.2.4. Inorganic pigments^^^^^ Inorganic pigments are also called mineral pigments. Mineral pigments are produced naturally and powdered red ochre, yellow ochre, green ochre, the main component of which is ferric oxide, and natural lapis lazuli (ultramarine), have long been used as pigments. However, these minerals include impurities and cannot be said to be brilliant colors. Since the quality is not constant, nowadays, most inorganic pigments are synthesized.

Color and cosmetic color materials 89 Table 3.4. Classification of inorganic pigments Usage Classification

Pigment

Extender Pigments

mica, talc, kaolin, calcium carbonate, magnesium carbonate, anhydrous silicate, aluminum oxide, barium sulfate

Coloring Pigments

ferrous oxide, yellow iron oxide, black iron oxide, chromium oxide, ultramarine, Prussian blue, carbon black

White Pigments

titanium dioxide, zinc oxide

Perlescent Pigments

titanium dioxide coated mica, fish scales flake, bismuth oxychloride

New functional Pigments

boron nitrite, photochromic pigment, synthetic phlogopite, synthetic iron included phlogopite, hybrid fine powder

Generally, inorganic pigments have good light and heat tolerance; they have excellent characteristics such as insolubility in organic solvents but on the other hand, they are not as brilliant as organic pigments. Table 3.4 shows the main classification of inorganic pigments based on use, but when they are used in cosmetics, these pigments are combined with and dispersed in oily materials, aqueous materials, surfactants, perfumes and pharmaceutical agents, etc. Inorganic pigments play a large role in cosmetics; color pigments adjust the product color, white pigments control the covering power and the color. In addition to adjusting the color as dilutants, extender pigments adjust the product usage characteristics (extensibility and adhesiveness) as well as the luster, etc. Moreover, extender pigments are used to maintain the form of the product. Perlescent pigments give the product a lustrous quality. New functional pigments are mixed in the product to increase the product usability and makeup effectiveness; some recently-developed pigments increase the UV blocking effect. The following section explains some typical pigments classified according to use. 3.2.4.1. Extender pigments^^^'^^ Mica, talc and kaolin are powdered clay minerals and are used in various particle sizes, forms and thicknesses, etc. Clay minerals have a layer structure and are hydrated silicates including silicon (Si) and aluminum (Al) as the major components and magnesium (Mg), iron (Fe) and alkali metals (Li, Na, K), etc. Consequently, clay minerals are found in a very wide range of types, depending on differences in the composition which in turn depends on the mineral deposit. Mica occurs in characteristic white sheets with the chemical formula KAl2(AlSi3)Oio(OH)2. The mica crystals are pale yellow or green hexagonal sheets of the monoclinic system; mica has a perfect cleavage surface plane (001) and can be split into thin sheets characterized by high elasticity. The main producers are India, USA, Canada, and Russia. In Japan, there is absolutely no production that can be used for cleaved sheets and all requirements are imported from India and Canada. The name silky mica (cericite) is very common, but this is basically muscovite. It is formed in fine crystalline agglomerates and the dry surface has a silky luster from which it probably takes its name. Consequently, silky mica is really fine muscovite.

90 New cosmetic science Table 3.5. General characteristics of clay mineral extender pigments ^^^^^^ Mineral Item ^"^^^^

Mica

Talc

Kaolin

Chemical formula

KAl,(AlSi3)0,(0H),

Mg3Si40io(OH)2

Al2Si205(OH)4

Molecular weight

398.4

379.4

258.2

White thin-sheet type crystalline powder

White thin-sheet type crystalline powder

White thin-sheet type crystalline powder

Monoclinic crystal

Monoclinic crystal

Monoclinic crystal

Form Crystal type Specific gravity

2.80

2.72

2.61

Hardness (Mohs)

2.8

1-1.3

2.5

Refractive index

1.552—1.588

1.539—1.589

1.561—1.566

7.0—9.0

8.5-10.0

4.5—7.0

|pH

Mica in thin particulate sheet form has high elasticity so it adheres well to the skin. In addition, since it has many excellent characteristics, such as lack of caking due to its elasticity, it is a very important pigment in compact powders. Talc is hydrated magnesium silicate with the chemical formula Mg3Si40io(OH)2. It occurs naturally as fine crystals or as a leaf-like crystalline agglomerate. It feels smooth to the touch which is why it is called talc. Good quality talc is white but it may be gray or pale green due to impurities. Talc ore is produced in many countries worldwide but Japanese talc contains many impurities such as iron so it is not pure white. High-quality talc ore is imported from China, Korea and Australia. The particle shape is generally a thin plate. Talc is used in cosmetics because it provides a smooth touch and spreadability. Georgia in the USA and Cornwall in the UK are world famous for production of highquality kaolin. In the UK, this high-quality kaolin is called china clay. The name kaolin originates from the pure, white, high-quality clay from the Kauling district and used in ancient China for porcelain production Kaolin consists of hydrated aluminum silicate (Al2Si205(OH)4). The highly-crystalline form has regular hexagonal plates but the non-crystalline form is finely amorphous. In addition, the thin plate particles have high adhesion to skin as well as good oil and water absorption making kaolin useful for cosmetics. The general features of the extender pigments are shown in Table 3.5. 3.2.4.2. Coloring pigments^^^^^^ There are three types of iron oxide used for pigments: red iron oxide or red ochre, yellow iron oxide or yellow ochre, and black iron oxide. Common red ochre, or bengala, was imported from Bengal in India, hence its name. Bengala is actually ferrous oxide (Fe203) or hematite. The chemical formula of yellow iron oxide is (FeO(OH)) and it is known as geothite. The chemical formula of black iron oxide is Fe304 and it is known as magnetite. These iron-oxide pigments have been produced from ancient times by pulverizing and burning the ores but the colors are variable as a result of impurities and color stability is

Color and cosmetic color materials 91

pH3-5 50~70°C

o-FeOOH Yellow Geothite Needle-like ore Needle-like

Fe(0H)2 Dehydration Reduction pH 7 or more 80-100°C

220~400°C

a-Fe203 Red Red iron oxide Hematite Red iron ore Needle-like, granular-tospherical

300 S 400°C

Fe304 Black Magnetite Magnetic iron ore

Oxidation 180~450°C

450°C or more r-FezOs Brown Maghemite

Needle-like, granular-to spherical Ferric sulfate solution is neutralized with caustic soda and various iron-oxide pigments are produced by controlling the temperature and pH of the solution.

Fig. 3.11. Production of iron-oxide pigments (red, yellow, and black).

poor so modern products are manufactured by wet synthesis using ferric sulfate or ferric chloride as raw materials. Fig. 3.11 shows the production of various iron oxides and iron compounds starting from Fe(0H)2 as the raw material. Three different iron oxides can be manufactured by controlling the reaction conditions. In addition, the particle size can also be controlled by the reaction conditions permitting production of iron-oxide pigments with different particle sizes. Ultramarine^^) is a brilliant blue pigment produced since ancient times by pulverizing natural lapis lazuli and purification. However, in the early 16th century a synthetic blue pigment called azurumultramarimum (meaning deeper blue than the sea) and shortened to ultramarine was distinguished from the natural product. In 1828, Mr. Guiment of France and Herr Gmelin of Germany simultaneously discovered an artificial production method. Subsequently, ultramarine was manufactured in large amounts at low cost in many countries^^^. Ultramarine is composed of 37-43% Si02, 21-25% AI2O3, 19-25% Na20, 10-13% combined sulfur, and 0.5-1.5% Na2S04. The molecular structure has yet to be fully clarified, but in the early 20th century, Hoffman confirmed the basic chemical formula to be Na6Al6Si6024S^ (-^ = 4). Recently, X-ray crystallography has confirmed that the alumino-silicate skeletal structure is correct. The color of ultramarine is considered to be the result of the resonance between some kinds of sulfur (Sx), which have various oxidation numbers and coexist in the structure. Ultramarine can be manufactured by burning a mixture of kaolin, diatomaceous earth, sulfur, soda ash and reducing agents (carbon, charcoal and Rosin) and then crushing and

92 New cosmetic science

sieving. Pigments with different characteristics can be produced by controlling the mixture ratios, and burning conditions as well as the sieving. The color is a brilliant blue but the coloring power is low and the color is only stable at up to 300°C in air; at temperatures above 300°C, the color begins to fade. Moreover, although ultramarine is resistant to alkalis, at acidic pH values below 5, the color fades due to production of hydrogen sulfide, so it is imperative to understand the characteristics in considering usage. 3.2.4.3. White pigments^^^ There are many types of white pigments. Two of the most popular are titanium dioxide and zinc oxide. Titanium dioxide has a high refractive index and the particle diameter is very small so it has excellent optical qualities such as whiteness and covering power. Moreover, it has high light, heat and chemical resistance making it an excellent white pigment. Titanium dioxide is produced commercially using the sulfate or chloride method, and by the gas-phase method in which titanium tetrachloride is hydrolyzed in an oxyhydrogen flame. The characteristics of the titanium dioxide differ with each of these methods. Most titanium dioxide sold within and outside Japan can be classified into three types: rutile, anatase, and ultra-fine powder. The general characteristics of each are shown in Table 3.6. Ultra-fine powder titanium dioxide has a very low bulk density and excellent dispersability so it has different characteristics to the titanium dioxide used in pigments (rutile and anatase). In addition, the ultra-fine titanium dioxide has low coloring and covering power because its particle size is a tenth part of the wavelength of light (30'-50 nm). Consequently, it has little influence on hue and improves the characteristics of products. In other words, when ultra-fine powder titanium dioxide is mixed in cosmetics, the transparency is excellent, harmful UV rays can be prevented from reaching the skin and sunscreens can be produced easily. Table 3.6. General characteristics of titanium dioxide Item Chemical formula Molecular weight

Rutile

Anatase

Ultra-fine Powder

Ti02

Ti02

Ti02

79.90

79.90

79.90

White fine powder

White fine powder

Soft white fine powder

Tetragonal 4.58 2.95

Tetragonal 3.78 9.49

Tetragonal Anatase 70 Rutile 30

Specific gravity

4.2

3.9

4.0

Refractive index

2.71

2.52

2.6

Hardness (Mohs)

6.0—7.0

5.5-6.0

-

pH(5% dispersion)

6.0-7.5

5.5-7.0

3.0-4.0

Dry weight at 105°C(%)

0.2

0.2

1.5

Melting point

1825

Changes to rutile

Changes to rutile

Properties Crystal form Lattice constant a (A) Lattice constant c ( A )

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Zinc oxide is also in widespread use as a white pigment in cosmetics, and is manufactured by the dry or wet methods. In the dry method, metallic zinc is heated and the zinc vapor is brought into contact with air to produce yellowish white fumes which condense as zinc oxide. This requires cooling. In the wet method, a solution of soda ash is added to a zinc solution to produce basic zinc carbonate which is washed, filtered and dried and then decomposed by burning to produce fine zinc oxide with a large specific surface area. This is called active zinc oxide. Zinc oxide crystals are hexagonal (wurzite type ore) and the particle form has many needles. Zinc oxide is not toxic and does not dissolve in water or alcohol. However, it is soluble in acids, alkalis and aqueous ammonia. It becomes yellow when heated strongly and returns to its original color on cooling. However, when it is converted to zinc sulfide by hydrogen sulfide, the color does not change. It is also effective in blocking UV light; the particle size is around 500 nm and the specific gravity is high at 5.4-5.6. The refractive index is around 1.9-2.0 and the covering power is low. The light, weather and heat resistance are high, meaning that it can be used with most other pigments. 3.2,5. Perlescent (nacreous) pigments^^^ Perlescent (nacreous) pigments are pigments having a special optical effect so they give a nacreous, or metallic effect to the material in which they are used. Perlescent pigments have a long history; in 1656, Mr. Jaczuin, a Frenchman, discovered natural pearl essence which he used to begin industrial manufacture of synthetic pearls. However, since natural pearl essence is very expensive, development of synthetic perlescent pigments led to the discovery of mercuric chloride, lead hydrogenphosphate, lead hydrogenarsenate and basic lead carbonate, which were able to produce the same perlescent effect as natural pearl essence. However, pigments containing lead or mercury compounds cannot be used in cosmetics, leading to the discovery of bismuth oxychloride, but this compound is unstable. In 1965, the Dupont Corporation developed titanium-dioxide coated mica and this is currently the main perlescent pigment. Titanium-dioxide coated mica (mica titanium) is formed of thin slippery sheets of mica coated with titanium dioxide. Mica is dispersed in an acidic solution of a titanium Table 3.7. Characteristics of perlescent nacreous pigments Titanium-dioxide Bismuth oxy- Lead hydrogenarsenate -coated mica chloride

Fish Scale Flake

Basic lead carbonate

Refractive Index

1.85

2.09

2.15

1.95

TiOs : 2.52 mica : 1.58

Specific Gravity

1.6

6.8

7.7

5.9

TiOs : 3.90 mica : 2.8

Average Size(/im)

30

8-30

Particle

Particle Thickness

0.07

0.05-0.34

8-20

7

0.15

0.07

20 Ti02 : 0.06-0.17 mica : 0.25

94 New cosmetic science Table 3.8. Interference color and thickness of optical film Visible light (nm)

400-450

450-500

500—570

570—610

610—760

Thickness of optical film(nm)

210

265

285

330

385

Interference color

Yellow

Blue

Green

Complementary color

Purple

Orange-yellow

Red

Orange-yellow Red/red-purple Blue

Green

salt, which is then heated and hydrolyzed to precipitate hydrated titanium oxide; this is then heated to 900-1000°C. The titanium dioxide in this case is just the normal anatase form, but in the case of the rutile form, the titanium-dioxide-coated mica is manufactured by coating the sheet mica with tin oxide before precipitating titanium oxide and then precipitating the hydrated titanium oxide and heating. The color of the perlescent pigment is produced differently from the color of colored pigments. Colored pigments either absorb or reflect light to produce color, but the thinsheet particles of the perlescent pigment are aligned in parallel in the coloring material and reflect interfered light to give the perlescent effect. In the case of titanium-dioxidecoated mica, the interface between the mica and titanium oxide also reflects the light to create interference; the wavelength of the interfered light varies according to the thickness of the titanium oxide layer to produce a variety of interference colors. Table 3.7 shows the characteristics of perlescent pigments. Table 3.8 shows the relationship between the reflected light (interference color) and the thickness of the titanium oxide film of titanium-dioxide-coated mica. When mica is coated with iron oxide instead of titanium oxide, or when the titanium oxide layer is covered with a coloring pigment, perlescent pigments of different colors can be obtained. For example, when titanium-dioxide-coated mica producing a blue interference color is coated with a deep blue pigment, a pigment with both blue interference and transmitted colors is obtained; when it is coated with a carmine, a pigment with blue interfered light and red transmitted light is obtained. Recently, high-quality titanium-dioxide-coated mica has been developed^^) with excellent weather endurance so it can be used outside. Some or all metallic powder paints used previously on cars, etc., to give a perlescent luster are being replaced with titaniumdioxide-coated mica pigments. 3,2,6. Polymer powders In the early stages, irregular-shaped polymer powders were used, but progress in polymer technology has made it possible to manufacture spherical powders which are now used widely in makeup cosmetics. Moreover, lamination technology has made it possible to produce laminated-sheet particles which produce beautiful powders with many interference colors due to the differences in the refractive indexes. With future technological progress, it will probably be possible to produce new powders. With polymer powders it is important to confirm the solubility in oils and solvents, as well as the swelling and whether or not components such as residual monomers and pharmacological

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agents are absorbed. This section explains the principal polymer powders used in cosmetics. 3.2.6.1. Polyethylene powder Polyethylene powder is obtained from the polymerization of ethylene in three densities: low, medium and high, depending on the manufacturing method; each density has a different melting point and specific gravity. The low-density powder is soluble in liquid paraffin and is used to thicken, but medium and high density polyethylene powder is used as powder the spherical and fine powders for makeup. They are also used as exfoliants. -f CH2-CH24-„

3.2.6.2. Polymethylmethacrylate This is a polymer of methylmethacrylate and a spherical type product is produced from emulsion polymerization. For use in makeup products, the particle size is 10 /um or less.

CH3

I

-hCH2-C —

I

COOCH3

3.2.6.3. Polyethyeleneterephthalate polymethylmethacrylate laminated powder This laminated polymer is alternately composed of thin membranes of polyethyeleneterephthalate and polymethylmethacrylate in a multilayered structure. Them laminated polymer is made into a film, stretched and then shredded. The thin and transparent shreds produce a rainbow color and are used in makeup and soaps. It has low resistance to solvents so it cannot be used in solvent systems. 3.2.6.4. Nylon powder Spherical nylon powder 12 is obtained by rapid ring-opening polymerization of (olaurolactum, the raw material for nylon 12, in an inactive medium. The particle size distribution is 2-12//m and the average particle diameter is 5 //m; it has excellent heat and solvent resistance and is not easily deformed by pulverization. It is use in makeup products, particularly foundation to increase the spreadability. + NH(CH3)nC+„ I 0

96 New cosmetic science

3,2.7. New functional

pigments

Cosmetics and makeup products, especially foundations, cannot continue to be improved in terms of function and usage through the use of the same pigments that have been used until now. Consequently, recently, there has been active R&D into special function pigments. Some of these are explained next. 3.2.7.1. Boron nitrite^^^ Clay minerals such as talc feel good to the touch, but have low covering power. Conversely, titanium dioxide has good covering power, but poor feeling to the touch. Moreover, the average particle size of sheet-like mica and talc crystals is several thousand nanometers while that of titanium dioxide is several hundred nanometers; these large differences in size and form make it extremely difficult to disperse these materials uniformly together in cosmetics. If it were possible to find a white pigment for use in cosmetics that combined good feeling to the touch with good covering power, it would be possible to greatly improve the characteristics of makeup cosmetics. Hexagonal boron nitrite (h-BN) has extremely good lubrication properties, and good chemical stability at high temperatures so it is used as a solid lubricant and fine ceramic material. Moreover, the crystalline structure and physical properties resemble those of graphite so it is nicknamed white graphite. h-BN is manufactured by mixing boric acid with urea in an ammonia gas flow and then by heating the resultant fine powder to 1600-1800°C. h-BN formed at high temperatures of 1800°C has extremely good lubrication properties; better than the cosmetic powders widely used and 3-4 times the covering power of talc or mica and about 30% that of titanium dioxide. This type of h-BN is a superior cosmetic pigment combining both good lubrication properties and covering power. 3.2.7.2. Synthetic mica Since natural minerals always include impurities, the whiteness and transparency are reduced. This problem led to the development of synthetic mica closely resembling mica obtained from natural clay minerals in properties and structure. Synthetic mica was first investigated in 1938 by Inekichi Noda, who performed the basic research, and was subsequently researched in detail by Toshinobu Daimon. In synthetic mica {KMg3(AlSi30io)(F)2}, the (OH) of the natural crystal structure {KMg3(AlSi30io)(OH)2} is replaced by (F). Synthetic mica is produced by mixing anhydrous silica, aluminum oxide, magnesium oxide, and potassium silicofluoride, melting at 1400-1600°C, and crystallizing at 12001400°C. The final product is formed by cooling, coarse grinding, pulverizing, classifying, washing, filtering, drying and grinding. The physical properties of synthetic mica vary depending on the manufacturing conditions. In particular, the coarse grinding, pulverizing, and sieving are especially important. Consequently, the special features of smoothness, luster, whiteness, feel and transparency depend on paying sufficient attention to these processes and excellent characteristics can be obtained for synthetic extender pigments^"*) especially for use in powder cosmetics.

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3.2.7.3. Photochromic pigment Cosmetics applied under artificial light inside a room can appear like a white mask under strong outdoor light. This phenomenon is called the white masking. If makeup could adjust to the light strength, and could keep a natural appearance without white masking, it would be the ideal makeup. In other words, if we could develop a pigment which could change its lightness (value) according to the strength of the light, it would be possible to make-up without the white masking phenomenon occurring. The color of the reflected light can be changed reversibly by combining small amounts of metallic elements in with titanium dioxide. And a new photochromic pigment that can change its lightness (value) according to the strength of the light has been recently developed in Japan. When this photochromic pigment is mixed in foundation, it is possible to produce makeup that does not cause white masking^^). 3.2.7.4. Inorganic pigment coated spherical organic powder, hybrid fine powder Spherical powders feel very smooth on the skin but although titanium-dioxide powder has an average particle size of 300 nm and good covering power, it does not feel smooth on the skin. Hybrid fine powder (HFP) combines the advantages of both. HFP is composed of a nucleus coated with another powder. The method by which the powder sticks on the nucleus is unclear, but it is believed to be due to physical attraction and static electricity. Recently, HFPs are being increasingly used in cosmetics and attention is focusing on new materials. For example, when spherical nylon powder with an average particle diameter of 5-7 /^m is processed in a dry ball mill with titanium dioxide, the nylon powder becomes coated with a regular layer of titanium dioxide. This HFP is very smooth and has high covering power. The application of this type of technology makes it possible to make use of all advantages ultrafine powders. Until recently, cosmetics were used to beautify the skin, protect against UV rays, and cover small blemishes. In the future, we believe there will be progress towards keeping skin young through the synergistic effect with skin care. Development of new functional pigments will require new visions.

References 1. 2. 3. 4. 5. 6. 7. 8. 9.

Noya, Y.: Industrial Color Science, Asakura Shoten, p. 4, 1989. JIS Z 8102 (Colour Name). JIS Z 8721 (Specification of Colours According to their Three Attributes). JIS Z 8701 (Specification of Colours According to the CIE Standard Colorimetric System). Billmeyer and Salzman: Principles of Color Technology, 2nd edn., Wiley, Chicester, 62, 87, 1981. Japan Color Science Association ed.: New Color Science Handbook, Tokyo University Press, 1980. Saito, T., Murui, T., Tate, K.: Fragrance J., 13 (4), 10 (1985). Tanaka, T.: Paint Eng., 6, 12 (1981). Ministry of Health and Welfare Regulation 30, Tar Colors Permitted for Use in Pharmaceutical Drugs (31 August 1961). 10. Ministry of Health and Welfare Regulation 55, Revised Tar Colors Permitted for Use in Pharmaceutical Products (13 December 1972). 11. The Japanese Standard of Cosmetic Ingredients, 2nd edn. Note: Yakuji Nippo Ltd., 1984.

98 New cosmetic science 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25.

Japan Cosmetic Association ed.: Permitted Colors Handbook, Yakuji Nippo Ltd., 1988. Takahashi, N., Miyasaka, S., Tasaka, I., Miura et al.,: Tetrahedron Lett., 23 (49), 5163-5166 (1982). Sueno, T., Iwao, S.: Clays and Their Use, Asakura Shoten, 1972. Sudo, T.: Clay Mineral Science, Iwanami Shoten, 1974. Iwaki, S., Minato, H.: Clays Handbook, Gihodo, 1967. Yoshimoto, B.: Mineral Science, Gihodo, 1963. Sentani, T.: Inorganic Chemistry, 3 vols., Sangyotosho, 1972. Inoya, K., Arakawa, M.: Characteristics of Powders, Sangyou Gijutsu Center, 1987. 33rd Pigment Introductory Lectures: J. Jpn., Soc. Color Mater., 1991. Suzuki, F., Tanaka, M.: J. Jpn., Soc. Color Mater., 55 (6), 413-428 (1982). Kimura, A., Suzuki, F.: J. Jpn., Soc. Powder Metall., 34 (9), 497 (1987). Ohno, K., Kumagai, S., Suzuki, F., Saito, T.: J. Jpn., Soc. Color Mater., 170 (1988). Ohno, K., Kumagai, S., Suzuki, F., Saito, T., Ando, Kosugi: J. Jpn., Soc. Color Mater., 68 (1986). Ohno, K., Kumagai, S., Suzuki, F., Saito, T., Tsujita: J. Jpn., Soc. Color Mater., 202 (1990).

4

Cosmetics and fragrances

Cosmetics and perfumes are closely related. Powerful women in both the east and west, such as Queen Cleopatra and the Chinese Dowager Empress Yang Guifei, used fragrances to advantage. Large amounts of spices, etc., were used by the Egyptians in embalming mummies. During the medieval period when the Americas were "discovered", voyagers were attempting to monopolize the products of the Asian Spice Islands. Consequently, it is true to say that perfumes have been linked to the activities of mankind throughout history. In the present age, perfumes are used both to beautify the wearer and to give attractive scents to cosmetics thereby creating an internal feeling of beauty. At the same time as making people nearby feel good, the person using the perfume also has a sense of inner well being. Smell is one of the five senses and this chapter first explains the sense of smell and its nature, and then proceeds to discuss how fragrances are used in cosmetics.

4.1. Olfaction 4.1.1. Roles of olfaction Olfaction has two roles. 4.1.1.1. Basic role Olfaction plays a major role in the lives of all animals; it helps protect animals from enemies and also helps them find food. For example, human beings are easily able to detect danger signals such as the unpleasant smell of gas and burning, and olfaction plays a fundamental role in determining whether something is good to eat. Furthermore, in the animal kingdom, olfaction is very important in helping males and females find mates. The substances sensed in this case are called pheromones. In the animal kingdom, there is no doubt that olfaction protects life and facilitates propagation of the species. 4.1.1.2. Psychological role In human beings, the psychological role of olfaction has become more significant than the basic role. Pleasant fragrances can have a calming effect, enrich the spirit and create a pleasant feeling. Conversely, unpleasant smells can dampen the spirits. As a consequence, com99

100 New cosmetic science

ing into contact with pleasant fragrances in everyday life is important for invigorating the spirit and mind. 4.1.2. Nature of olfaction 4.1.2.1. Adaptation If the same odor is smelled continuously, the ability to sense the odor drops. This is called adaptation. A typical example is the loss of the ability to detect the odor of city gas. Similarly, when the same perfume is used continuously, the wearer's sensitivity to the perfume gradually becomes dulled. However, people around her still perceive the fragrance strongly. 4.1.2.2. Memory A characteristic feature of the sense of smell is the ability to remember smells and associate them with events. 4.1.2.3. Individual variation There are large individual variations between people's ability to perceive strong and subtle odors. In general, women have a more sensitive sense of smell with the highest sensitivity being from the mid-20s to mid-30s. 4.1.2.4. Keenness Human beings are said to obtain most information via the sense of sight, but other animals obtain large amounts of information via olfaction. The domesticated dog has one of the keenest senses of olfaction which is believed to be over 100 times more sensitive than that of human beings. 4.1.2.5. Strength and quality When absolute jasmine is analyzed, it is found to include indole. When this compound is smelled at high concentrations, it appears to smell like feces. However, at lower concentrations, it appears to smell floral making it at a very useful compound. Consequently, like pharmaceutical agents, it is very important to use perfumery raw materials at the appropriate concentration. 4.1.3. Olfactory

mechanism

Although there have been many theories concerning the olfactory mechanism, the current concept is that the odorant is drawn in by breathing and stimulates the olfactory sensory neurons in the mucous membranes on both sides of the upper part of the nasal cavity. This chemical stimulation is converted to an electrical stimulus which passes via the olfactory neuron axons to the olfactory bulb and then to the central nervous system where the signals are interpreted as smell. 4.1.4. Body odor Body odor is both genetically determined and modified through lifestyle; it can also vary with disease. Food in particular has a large effect on body odor - meat eaters have a

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"meaty" odor while fish eaters have a "fishy" odor. People who eat food containing large quantities of strong smelling spices such as garlic, have a garlic odor on the breath and in the body odor.

4.2. Smell, fragrances and perfumery raw materials There are about 400,000 odorants if one includes pleasant and unpleasant odors. The words "fragrance" and "perfume" are generally used to describe pleasant smells, whereas the word "smell" is a neutral term used to describe both pleasant and unpleasant odors. Jasmine is a principal natural perfume with a beautiful scent. Analysis with highsensitivity equipment shows that it has more than 200 components ranging from jasmine lactone with a pleasant smell to indole with an extremely unpleasant smell, but the total composition creates a pleasant smell as a whole. We are surrounded by about 400,000 odorants many of which are used to create fragrances and perfumes. 4.2.1. History of perfume The roots of the word "perfume" are "per" meaning "through" and "fumum" meaning "smoke" suggesting that the first perfumes were pleasant smells obtained by burning woods and grass, etc. Neanderthal man was probably the earliest human to discover the pleasant smells obtained by burning fragrant woods. Since the earliest times, humankind has searched for plant and animal sources of medicines with which to relieve sickness and suffering. There must have been many fragrant materials amongst these materials which gradually came into use as natural perfumes from plants and animals. Clearly, medicines and perfumes originated from the same origins. The early Romans had the first culture to enjoy perfumes themselves and they used rose water extensively after bathing. The city of ancient Rome was lined with shops selling perfumes. With the establishment of the early states, many cultures shared the tradition of making supplications to their gods by burning fragrant herbs and woods. The desire to use pleasant perfumes taken from fragrant flowers and fruits was common to most people irrespective of region or season. In the 11th century, Islamic alchemists invented the steam distillation methods and discovered how to concentrate and separate ethyl alcohol which played an important role in the development of the culture of perfume. The medieval period was a "Dark Ages" as far as perfumes are concerned and little is known about their use except that some medicinal plants were grown in monastery herb gardens. In the 17th and 18th centuries, the technology for manufacturing natural perfumes was developed; the late 19th century saw progress in synthesis of aroma chemicals, and the 20th century has brought a wealth of fragrances and perfumes. 4.2.2. Role and importance of fragrances in cosmetics Human beings have long used vegetable oils, such as olive oil, and animal fats from cat-

102

New cosmetic

science

tie and pigs as cosmetics. These oils and fats were scented with flowers, etc., to make balms and pomades some of which are still in use today. Fragrances play an important role in cosmetics and add a satisfying scent to cosmetics for beauty and health, thereby making people who use cosmetics more attractive. Their purpose is not only to scent alcoholic fragrances such as perfumes and eau de cologne which are basically for creating personal attractiveness by pleasant odors. The same fragrances are also used in the same brands of body care products on the whole. Another important role of fragrance is the masking effect. When a person first opens cosmetics, they smell the product unconsciously. When a person first comes into contact with a new thing, it is a basic instinct to test the smell to see whether it is safe and secure. Some cosmetic ingredients have disagreeable off-odors which are masked by adding perfumes to make people feel comfortable using them. In addition to the design and shape of the container, smell is also one of the first characteristics of the cosmetic that the consumer experiences, so cosmetic fragrances play an important role in giving cosmetics a beautiful and attractive scent. It has been reported that pleasant smells affect comfortability and the effect of products, and also play an important role in the overall evaluation of cosmetics. Recent advances in research into the physiological and psychological effects of odors show that not only do they increase self-image in the eyes of others, they also have an effect on the bodies and minds of the users themselves. In the cosmetic and perfumery field, the term "aromachology" has been coined and is gradually coming into widespread use. For example, people under chronically high stress levels experience mental and physical changes; the hormone balance is thrown out of equilibrium, metabolism is adversely affected and the skin becomes rough. When considering cosmetics from the total viewpoint including aging, we must include both psychological and physiological balances. Scent not only creates a feeling of emotional comfort, it also affects the autonomic nervous system, endocrine systems and immune systems, and we are now discovering its role in maintaining and improving homeostasis. As a result, we expect that the main role of perfumes will be as an "internal cosmetic" for maintaining homeostatic balance. In addition, the bactericidal properties of perfume have long been known. In the times before there were any chemically synthesized antibacterial agents, fragrant plants were used widely for this purpose. Recently, environmental concerns have become important even in development of cosmetics offering a chance to re-evaluate the useful properties of perfumery raw materials such as their bactericidal and preservative effects. 4.2.3. Physiological and psychological effects of odors Useful perfumes not only have high preferences but also have various beneficial effects on the mind and body of the person experiencing them. Therapeutic use of perfumery raw materials has a long history and was used in both ancient China and Egypt. Many records remain on the therapeutic use of natural perfumes extracted from plants and animals at that time, especially their use as medicines. In the early 20th century, this

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medicinal use of natural perfumes was named "Aromatherapy" by R.M. Gatoffose, a French comparative pathologist. As its name implies, aromatherapy does not just study the effect of inhaling odors; it also deals with a variety of traditional uses of natural perfumes including their application in massage and bathing, as well as ingestion. In modern medicine, P. Rovesti of Milan University, clinically confirmed the sedative and stimulative effects of essential oils on nerves. Dr. Hasegawa of Akita University developed a therapy for psychosomatic disorders using traditional Japanese incense. Against this background, aromatherapy is a word that is easily confused with folk remedies using natural extracts and plant and animal materials containing pharmacologically-active ingredients. In recent years, a variety of effective perfumes have been used in cosmetics and bath preparations; since the term aromatherapy has a therapeutic and medical image, it has been thought inappropriate for cosmetic use. However, as a result of more active research into the physiological and psychological effects of odors on the body and mind, the word aromatherapy has been changed to the word aromachology which expresses the concept of studying the physiological and psychological effects of odors. Recently, aromachology research has focused on changes in parameters of the nervous system, such as brain waves and heart beat, caused by odors. Yamaguchi et al. measured changes in cardiac response during a simple task to auditory stimuli under different odors. They discovered citrus type fragrance increased concentration and produced higher attention levels; rose type fragrance had a calming and tranquilizing effect^\ Torii et al. measured CNV (contingent negative variation), a kind of evoked potential in brain waves, and observed the calming effects of lavender and the exciting effects of jasmine^^. In research on immunological parameters using a highly-stressed mouse, Yokoyama et al. found that stimulation with exposure to tuberose and oakmoss etc., recovered the immunosupressions caused by distress^^ As a result of these researches, fragrances demonstrating these effects have started being used in cosmetics. 4.2.4. Classification of perfumery raw materials Perfumery raw materials can be roughly classified into natural perfumes, and aroma chemicals (Fig. 4.1). Natural perfumes are divided into plant oils extracted from plants.

Natural Perfumes -

-Plant Materials Flowers, Leaves, Woods, Fruit Peels, Roots, Grasses, Resines, etc. •Animal Secretions— Musk, Civet, Ambergris Castoreum,

I— Fragrances Compounds

•Isolated Chemicals • Aroma Chemicals•Synthetic ChemicalsFig. 4.1. ClassiHcation of perfumery raw materials.

104 New cosmetic science

and animal extracts from animal glands, etc. Aroma chemicals are chemicals having a single chemical structure; they are divided into isolated chemicals separated from natural perfumes, and synthetic chemicals produced by chemical reactions. A blend of natural perfumes and aroma chemicals is called a fragrance compound.

4.3. Natural perfumes Natural perfumes are obtained from plants and animals by separation procedures such as distillation, solvent extraction, and expression. Natural perfumes are classified into materials obtained from plants and animals. Natural perfumes from plants are extracted from flowers, fruits, seeds, woods, branches and leaves, bark, and roots, etc. Natural extracts of animal origin are obtained from animal glands, etc. They are musk, civet, castoreum and ambergris. Among these, musk is the most important perfumery raw material and is more expensive than gold; it is a mysterious and precious fragrance. It is obtained from the testicles of the male musk deer living in mountainous regions of central Asia, and the best quality comes from Tibet and Sichuan. In China, it has been used as an aphrodisiac tonic, and medicine, etc. It is even said that Queen Cleopatra used musk to seduce Mark Anthony. Ambergris is as important as musk and is obtained from a pathological secretion from the intestine of the sperm whale. Many years ago, it was so expensive that the value of one large piece was equivalent to a lifetime's earnings. Civet is collected as a secretion from the glands of the civet cat living in Ethiopia and its odor changes when diluted in the same way as musk. Castoreum is obtained from glands near the reproductive organs of the beaver; it was first used as a medicine in ancient times and as bait for catching other beavers but in the latter half of the 19th century its value as a fragrance material was recognized. In recent years, musk and ambergris have been very difficult to obtain as a result of the Washington Treaty which bans international trade in protected species of wild animals and plants. As a result, recently, aroma chemicals with the same scents as natural musk and ambergris have been synthesized and are widely used. 4.3.1. Major natural perfumes Table 4.1"^^'^^) shows the main components and extraction methods for major natural perfumes. Fig. 4.2 shows some typical sources of natural plant perfumes. 4.3.2. Manufacturing methods and general names Fig. 4.3 shows the extraction methods and general names of extracted oils^'^^\ 4.3.2.1. Steam distillation When steam is blown onto fresh or dried plant materials, the essential oils are extracted in the steam vapor. In comparison to the expression and solvent extraction methods, this method is useful for production of heat-resistant oils and is widely used for collecting essential oils.

Cosmetics and fragrances

S. France Lavender

8 . Japan Thousands Of Islands Geranium

105

9 ^ S. France-Orange Blossom

Yugoslavia Oak moss

Head Space Instrument for Collecting Secnt of Cymbidium falx^ri Orchid

Fig. 4.2. Main fragrant plants.

4.3.2.2. Solvent extraction Solvents such as hexane and petroleum ether are used for this extraction. Many natural fragrances that have a low yield by steam distillation due to thermolability and/or high boiling point are obtained by extraction. The plant materials are soaked in the solvent

Table 4.1. Major natural perfumes Origin

Major Production Region

Extraction Method(Yie1d %)

Main Components(%)

Rose Oil (Rosaceae)

Rosa damascena and Rosa centifolia flowers

Bulgaria, Turkey, Southern France, Morocco

Steam distillation(0.01-0.04) Solvent extraction(0.07-0.1)

I-citronellol(30-59), geraniol, I-linalool, damascone, damascenone, p-phenyl ethyl alcohol, farnesol, nonyl aldehyde, rose oxide

Jasmin Oil (Oleacea)

Jasminium officinale var. flowers

Southern France. Egypt, Morocco

India, Solvent extraction (0.14-0.16)

benzyl acetate(65), d-linalool ( l 6 ) , jasmone, indole, phytol, cis-jasmon, benzyl alcohol, jasmin lactone, benzyl benzoate

Neroli Oil (Rutaceae)

Citrus aurantium sparnara fiowers

sub- Southern France, Italy, Steam distillation (0.08-0.15) Spain, Portugal

I-linalool(30), linalool acetate(7), d-nerolidol(6), geraniol, terpinol, pinene, nerol, camphene

Lavender Oil (Labiatae)

Lavandula flowers

Steam distillation(0.7-0.85) Solvent extraction(0.7-1.3)

linalyl acetate(30--LO), limonene, nerol, cineole, linalool esters, geraniol esters, d-borneol, lavandulol

Ylang Ylang Oil (Annonaceae)

Cananga odorata forma genuina flowers

Reunion Island, Madagas- Steam tlistillation(O.5-2.2) Solvent extraction(0.7-2.5) car

linalool, geraniol, benzyl alcohol, farnesol, sesquiterpenes

Tuberose Oil (Amaryllidaceae)

Pol y a n t h e s flowers

Southern France, Morocco,

Name

off icinalis

tuberosa

Southern France

Egypt

Solvent extraction (0.01-0.03)

geraniol, farnesol, benzyl alcohol, methyl benzoate, benzyl benzoate, methyl salicylate, methyl anthranilate, nerol

Steam distillation(0.5-1.5) Solvent extraction(O.01-0.1)

linalyl acetate, linalool, nerolidol, sclareol

-

(Labiatae)

Salvia sclaria flowers Southern Spain and leaves

Clove Oil (Myrtaceae)

Eugenia c a r o p h y l l a t a flower buds and leaves

hladagascar, Ceylon, Zan- S t e a m distillation(l5-17) Solvent extraction(4-6) zibar. Indonesia

Peppermint Oil (Labiatae)

Mentha piperita var. flowers and leaves

Europe. North America

Geranium Oil (Geraniaceae)

I'elargonium graveolens Reunion Island. Morocco, Steam distillation (0.15-0.3) Solvent extraction(0.3-0.4) Madagascar, Algeria leaves

Patchouli Oil (Labiatae)

Pogostemon cablin dried leaves

Malaysia, S u ~ n a t r a

Steam distillation(3-6)

patchouli alcohol (35-40), patchoulene, patchoulenon. p-caryophyllene, a-guajene, p-bulnessene

Sandalwood Oil (Santalaceae)

Santalum album \vood

Indonesia

Steam distillation(4.5-6.3)

a - p - s a n t a l o l ( 9 0 ) . santene. santenon, santenol, teresantalol, santalone, a-p-santalene

Glary Sage Oil

France,

Italy.

Steam distillation(0.3-1.0)

eugenol(70-90), acetyleugenol, methyl salicylate. pcaryophyllene, methyl-n-amylketone, methyl heptylketone lmenthol(40-50). menthone(16-25). isomenthone, 1,8 -cineole, p-caryophyllene, methyl acetate, menthofuran 1-citronello1 (25-50), geraniol(l0-15). menthone. linalool, geranyl formate, geranyl tiglate, citronellyl formate, isomenthone

Name

1

/

Origin

Major Production Region

I Extraction

Method(Yie1d %)

/

Main Components(%)

Steam distillation(0.2-1.8)

cinnarnic aldehyde(65-761, eugenol(2-5), I-phellandrene. pinene, linalool. 1, 8-cineole, caryophyllene

Hun- Steam distillation(0.3-1.0)

d-linalool(60-70), a . P-pinene, limonene, terpinene, phellandrene, gera~liol.I borneol, n-decyl aldehyde

Cinnamon Oil (Lauraceae)

Cinnaniomum zeylanicum bark

Coriander Oil (Umbelliferae)

Coriandrum seeds

Nutmeg Oil (hlyristicaceae)

blyristica fragrans seeds S.W. India, Sumatra, Brazil

Steam distillation(6-16)

sabinene(20-25), p-pinene, linalool, bol-neol, terpineol

Pepper Oil (Piperaceae)

Piper nigrum fruit

S.W. India. Sumatra. Brazil

Steam distillation(l.0-2.7)

p-pinene, sabinene, caryophyllene. elen101

Lemon Oil (Rutaceae)

Citrus limon fruit peel

Florida, California. Italy and blediterranean region

Expression(0.2-0.3)

d ~limonene(70), y - terpinene (7). citral, a , p-pinene. camphene, methyl heptenone, a-phellandrene, a - b e r gamotene, p-bisabolene

Orange Oil (Rutaceae)

Citrus sinensis fruit peel

Florida, California. Italy and Mediterranean region

Espression(O.2-0.4)

dlimonene(90), n d e c y l aldehyde, citi-al, d-linalool, nnonyl alcohol, d-terpinol, nootkatone

Bergamot Oil (Kutaceae)

Citrus aurantium gamia fruit peel

Opoponax Oil (Burseraceae)

Cornmiphora var. s a p

Vetiver Oil (Graniineae)

Vetiveria root

Oris Oil (Iridaceae)

Orris pallida root

Oakmoss Oil (Usneaceae)

Evernia prunastri oak- Yugoslavia, France moss

Musk oil

Musk Secretion from reproductive glands of male musk deer

Civet

Secretion civet c a t

Castoreum

Glands near reproduc- Siberia. N . America tive organs of beaver

Ambergris

Pathological secretion Indian Ocean from the intestine of the Oceans sperm whale

sativurn

Mexico, Morocco, gary, India

her- Calabrian peninsula, Cote Espl-ession(0.3-0.5) D' Azur

erythea

zizanioides

from

Ceylon, Java, Madagascar

male

linalyl acetate(35-401, cymene, decanal

camphene,

limonene,

I-linalool, limonene. citral, p-

Somalia, Ethiopia

Steam distillation(5-10)

bisabolene, y , 8-cadinene, caryophyllene, a-santalene. a-bergaiiiotene

Indonesia, IIaiti, Reunion Island, Seychelles

Steam distillation(O.6-3.0)

khusinlol(l3-22), vetiselinenol(lO12), a , b v e t i v o n e , vetiver-ol, vetivene

Italy and region

Steam distillation(0.2-0.1) Solvent estraction (0.005-0.06)

a , p, y-irone, linalool, geraniol, benzyl alcohol, n-decyl aldehyde

Solvent extraction (0.01-0.05)

evet-nic acid(2-3), a , p-thujone, atranorin, chloroatranorin. camphor, borneol, napthalene

Mediterranean

Tibet, Yunan, India, Si- Alcohol infusion chuan, Nepal

3-methyl cyclopentadecanone, muscopyrizine

Ethiopia

Alcohol infusion

civettone, skatole, indole

Alcohol infusion

castorin, castoramin, isocastoi-amin

Alcohol infusion

Amberein

coast

and

108

New cosmetic science Extraction Method 1. Steam Distillation

General Name Essential Oil

Volatile solvent Concrete - Extraction (Plants) (Organic Solvent Extraction) Concrete : ^ Absolute Pomade (Ethlanol Extraction) (Animal)Tincture (Ethanol Infusion) 2. Extraction - (Enfleurage) Non-volatile_ " Solvent Extraction

Pomade - (Maceration) -

3. Expression-

Essential Oils, Expressed Oils

4. Terpeneless, Sesquiterpeneless Methods -

Terpeneless Oils, Sesquiterpeneless Oils

Fig. 4.3. Extraction methods and general names of extracted oils.

and slightly warmed to extract the oils. The oil obtained is referred to as concrete and can be used without further processing but it is often re-extracted using cold ethanol and used as absolute oil. Another method called enfleurage, which is not commonly used now, involves placing flowers on animal fats from cattle and pigs applied to the surface of a glass plate, or chassis, and the flower scent is absorbed by the animal fats. Another uncommon method called maceration, involves absorbing the flower scent in animal fats from cattle and pigs heated to 60-70°C. The oil in which the scent is absorbed is called pomade, which can be used without further processing or can be re-extracted with ethanol. 4.3.2.3. Expression This method extracts essential oils from citrus fruit peel, etc., by expression. Citrus oils are unstable so they require processing at low temperature. 4.3.2.4. Terpeneless and sesquiterpeneless method The terpene hydrocarbons in essential oils obtained mainly from citrus fruits are difficult to dissolve in alcohol, and are easily oxidized and polymerized. These are sometimes used as perfumes without processing, but terpenes and sesquiterpenes are often removed from the essential oils by organic solvent extraction and fractional distillation. 4.3.3. Analysis of natural perfumes Fig. 4.4 shows the analysis of natural perfumes^\ Essential oils have long been analyzed by measuring their physicochemical constants. These values indicate the quality of the oils, are important in understanding the qualities

Cosmetics

and fragrances

109

I—Specific Gravity i-Physical Measurement—^

Refractive Index Optical Rotation

•—Solubility in Alcohol r Acid value U Chemical Analysis •

Ester Value Ester Value after Acetylation

Natural perfume-

Alcohol Content Aldehyde Content

-Analytical Methods

L Ketone Content, etc. Gas Chromatography Olfactory Gas Chromatography Head Space Gas Chromatography Mass Spectrometry Ultra Violet Absorption Spectrometry Infrared Absorption Spectrometry Nuclear Magnetic Resonance High-Performance Liquid Chromatography Liquid Chromatography L Thin-Layer Chromatography, etc.

Fig. 4.4. Analysis of natural perfumes.

of such oils and in detecting adulteration. The physical constants are specific gravity, refractive index, and optical rotation. Solubility is expressed in terms of solubility in ethyl alcohol and has a practical significance. The chemical constants used to assess essential oils are acid value, ester value, ester value after acetylation, alcohol content, aldehyde content, and ketone content, etc. These parameters show the characteristics of essential oils and are extremely useful in evaluating quality. Analysis of essential oils is extremely difficult since they are composed of several hundred constituents. Normally, gas chromatography is used to separate the volatile compounds. Mass spectrometry is used to determine the chemical structure. Both polarized and unpolarized material can be used as the liquid phase of the column of gas chromatography. For example, when the scent of the Oriental cymbidium is analyzed using polarized columns, methyl jasmonate, the key component, gives a single peak, but when an unpolarized column is used, methyl jasmonate forms two peaks. The second peak is attributed to the epi form of methyl jasmonate, which is responsible for the subtle scent of the Oriental cymbidium. By performing analyses using these two different liquid phases of the column, it is possible to find the important component in a mixture. Optical isomerism is also important in analysis of natural perfumes and an opticallyactive, fixed-phase column having the special characteristics of the dextro and levo forms is used for such analysis. d-Linalool in essential coriander oil has a floral scent with a woody note, while the Minalool found in essential bergamot oil has a sweet floral

110

New cosmetic

science

scent. These optical isomers impart major differences to the scent of essential oils. Optical isomers in essential oils, exist in the single d- or /- form, or as a mixture in which one form exists at a much higher level, and it is important to check the optical rotations affecting scent. In many cases either a flame ion detector (FID), or a thermal conductivity detector (TCD) is used as the detection equipment. However, a flame thermal detector (FTD) and a flame photodetector (FPD) are used to examine hetero compounds. Olfactory gas chromatography is an excellent method to examine components that have a large effect on the scent of an essential oil. The outlet of the column is divided into two; one side is connected to the detector and the other allows the gas to be smelled by experienced perfumery chemists. This permits identification of the actual smell of each component while monitoring the peaks on the chromatogram. Head space gas chromatography can be used for direct analysis of the volatile components from plants and essential oils. This is different from usual gas chromatography in that the volatile compounds are not analyzed directly. This is particularly useful for compounds with low boiling points. In addition, to concentrate the components, the volatile gas is absorbed by absorbent in a glass tube and then the absorbed components are expelled from the absorbent using solvents and heat for subsequent analysis (Figs. 4.2 and 4.5). Another method can be used to concentrate volatile components at low temperatures. Before these analyses, it is important to pre-fractionate the important compounds. Methods such as column chromatography, and thin-layer chromatography with a high separation rate for single compounds are used. In addition, liquid chromatography and high performance liquid chromatography are used for analysis of high-molecular weight and/or high-boiling point compounds as well as thermally-unstable compounds. UV absorption spectrometry, infrared absorption spectrometry and iH,i3C-nuclear magnetic resonance methods are useful in determining structure.

Air

Activated Carbon Column

Fig. 4.5. Scent collection equipment.

Cosmetics and fragrances

111

4.4. Aroma chemicals Since the latter half of the 19th century, when the foundations of terpene chemistry were laid, a great many synthesis technologies have been developed. As one example, Ruzicka won the 1939 Nobel Prize in Chemistry for his work on macrocyclic chemicals. As a result of increasing demand for perfumes into the 20th century, coupled with the high cost of land and labor, the prices for natural perfumes have become prohibitively high and there is a shortage of supply. Consequently, demand cannot be met only by natural perfumes. As a result, aroma chemicals have dominated the market due to their low cost, high production volumes and stable supply. In addition, new chemicals with good smells not found in nature have been synthesized and expectations for aroma chemicals are growing steadily. Aroma chemicals are classified into two types: isolated aroma chemicals obtained by extraction, purification, and crystallization of the contents of natural perfumes, as well as by fine chemical processes; and pure aroma chemicals manufactured through organic chemical processes. 4.4.1. Typical aroma chemicals^'' Aroma chemicals are classified according to structure into hydrocarbons, alcohols, aldehydes, ketones, esters, lactones, phenols, oxides, and acetals, etc., based on the functional group. Table 4.2 shows some typical aroma chemicals. In addition, the following types of compounds are also used as aroma chemicals. (1) Alcohols: geraniol, citronellol, terpineol, menthol, santalol, bacdanol (2) Aldehydes: lyral, lilial (3) Ketones: damascone, methylionone, irone, iso-E super, acetyl cedrene, muscone (4) Esters: benzyl acetate, methyl dihydrojasmonate, methyl jasmonate (5) Lactones: jasmine lactone, cyclopentadecanolide, ethylene brassylate (6) Oxides: galaxolide, ambroxane 4.4.2. Advances in synthesis methods As a result of recent advances in synthetic chemistry, aroma chemicals, which were used as racemic compounds, are now the subject of research into optically-active substances. The methods use either optically-active catalysts or enzymes, or optical cleavage based on chromatography and crystallization. In particular, bioexchange using enzymes and microorganisms and other such methods are becoming important in synthesis procedures.

4.5. Fragrance compounds The process of imparting a fragrance to cosmetics is called perfuming. The previously described natural perfumes and aroma chemicals are rarely used on their own; in most cases, they are blended according to the purpose. Such fragrances are called fragrance compounds.

112

New cosmetic science Table 4.2. Typical aroma chemicals Chemical Classification Monoterpenes

Aroma Chemicals

Chemical Structure

Limonene

o u a o Sesquiterpenes

>%

Odor Orange

CH3

S

Molecular Formula and Weight 136.24

CHa'^CH, /?-carophyllene

^15^.24

CH3

Woody

204.36

ACH; LII3 1 CH3

Fatty alcohols

cis-3-hexenol

\

CeH,20 100.16

Fresh leaves

OH

CH3

CioHigO

Lily of Valley

CH3

CH3

CH = CH

/

CH3CH2

M 0 n 01 e r p e n e alcohols

linalool

C/2

O

<

Sesquiterpene alcohols

farnesol

CH2CH2OH

154.25

222.37 [ ^ ^

the

Fresh green and floral

C15H26O

CH3

green

CH20H

CH3 CH3

Aromatic alco- /? - p h e n y l e t h y l hols alcohol

Fatty aldehydes Terpene hydes

2,6 nonadienal

CsHioO 122.17

Rosy

=CHCHO

CeHuO 138.21

Violet, cucumber

CH3

CioHieO

Lemon

CH2CH20H

6

CH3CH2CH = C H C H 2 C H 2 C H

alde- Citral

152.24

C^HO CH3

Aromatic alde- a - h e x y l c i n n a mic aldehyde hydes

Alicyclic ketones

/?-ionone

CH3

(CH,)5CH,

1 CH=C-CHO

6 CH3

CH3

^ ^ C H 3

^

Jasmin

C15H20O

216.33

Violet diluted

192.30

1

when

Cosmetics

Chemical Classification

Aroma Chemicals

Chemical Structure

Terpene ketones

Molecular Formula and Weight C10H14O

CH3

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and fragrances

Odor Spearmint

150.22

Cwf ^CH^ Macrocyclic ketones

cyclopentadecanone

(CH2)l2 ""CH2

I

CH2

Terpene esters

linalyl acetate

I

C15H28O

Musky

224.39

C= 0

CH3 OCOCH3

196.29

Bergamot and lavender

^14^112^2

Faint balsamic

CH3 CH3 ^' H

Aromatic esters benzyl benzoate

Lactones

CH2OCO

212.25

y-undecalactone

C11H20O2

Peach

184.28

Phenols

eugenol

OH

doHi2U2

Clove

164.21

.OCH3

CH2CH — CH2

Oxides

rose oxide

CioHisO

CH3

154.25

Green floral

and

O^^CH II C CH3

Nitrogen pounds

Acetals

Schiff base

com-

Indole

CH3

CgH.N 117.15

Co

phenyl acetaldehyde dimethylacetal

OCH3

^10^114^2

Fecal when strong, jasmin when dilute Faint hyacinth

166.22

CH2CH OCH3

aurantiol

C18H27NO3

CH3

CH-N CH3

I CH3 OH

COOCH3

305.43

Orange som

blos-

114 New cosmetic science

4.5.1. Base compounds^"' 4.5.1.1. Floral base Flower scents form an historically important core group and they have long been used by people in every culture. The most important base compounds are rose, jasmine, muguet, lilac, carnation, tuberose, hyacinth, orange flower, violet, heliotrope, gardenia, honeysuckle, jonquil, narcissus, freesia, ylang ylang, daphne, etc. The three main floral bases, rose, jasmine, and muguet are described below. (1) Rose base: The rose is a popular flower closely associated with daily life. The color, form and fragrance are all very popular. Whatever the perfume, rose makes it seem more complete. In addition, due to the development of aroma chemicals with the special characteristics of rose, a large number of unique perfumes have appeared on the market. Rose type formula (%) Phenyl ethyl alcohol 25.0 Geraniol 5.0 Citronellol 48.0 Linalool 12.0 Eugenol 2.0 Nerol 1.0 Aldehyde Cn undecylenic 10% 1.0 Aldehyde C^ lauric 10% 2.0 Amyl phenylacetate 5.0 Rose oxide 0.5 2.5 Geranyl acetate Damascone alpha 10% 1.0 (2) Jasmine base: In contrast to the queenly rose, jasmine is the flower of kings. The sophisticated scent of jasmine makes it just as an important fragrance as rose, and it is one of the essential elements of the perfumer's palette. It also blends well with other fragrances. Jasmine type formula (%) Benzyl acetate 17.0 Hexyl cinnamic aldehyde 43.0 Indole 10% 2.0 Hexyl salicylate 8.0 Methyl dihydrojasmonate 10.0 Eugenol 10% 4.0 Damascone alpha 1% 4.0 Mayol 8.0 Undecalactone gamma 10% 4.0 (3) Muguet base: Muguet does not have the brilliant fragrance of rose and jasmine, but is a popular fragrance with Japanese. It has a clear green note and refreshing nuance. Since a very similar fragrance to the living flower can be duplicated by blending, natural muguet oil is not used. Muguet type formula (%) Linalool 3.0

Cosmetics and fragrances

Ylang ylang oil Rhodinol Heliotropine Cyclamen aldehyde Lilial Lyral Mayol Dimethyl benzyl carbinol Bergamot oil Benzyl acetate Phenyl ethyl ether

115

1.0 15.0 4.0 2.0 25.0 10.0 15.0 5.0 7.0 2.5 10.0

4.5.1.2. Woody base The typical woody bases are the dry and elegant vetiver types, the heavy and sweetlysexy sandalwood types, the strongly-exotic patchouli types, as well as the cedarwoods. 4.5.1.3. Chypre base Chypre is the archetype perfume developed by Coty in 1917"^^. It has the characteristic scent of a mixture of bergamot, oakmoss, orange, rose, jasmine, musk and amber, etc., and is an important base in blending. 4.5.1.4. Citrus base This base is made from perfumes such as bergamot, lemon, orange, lime, grapefruit and mandarin and is used mainly in light colognes. 4.5.1.5. Green base These bases create the impression of cut grass and leaves or vegetables such as cucumber and tomato. The first perfume to use this type of fragrance was Vent Vert marketed byBalmainin \9A5^^\ 4.5.1.6. Fougere base Fougere takes its name from the archetype cologne "Fougere Royale" (Houbigant)^^^ marketed in 1882. In addition to perfumery raw materials such as lavender, oakmoss, and coumarin there are also floral notes like rose and jasmine, woody notes like sandalwood, vetiver and patchouli, and tenacious themes of musk and amber. It has wide appeal as a masculine fragrance. 4.5.1.7. Oriental base This name is given to fragrances imported from the Orient into Europe. They have balsamic and vanilla notes with woody and animal notes and are characterized by a powdery sweet strong fragrance. However, more recently, lighter floral semioriental and fioriental types have become more popular. 4.5.2. Other base compounds The base compounds described above form the framework of the perfume but there are

116

New cosmetic science

Other fragrances that are used in small quantities to modify the fragrance and develop body. 4.5.2.1. Fruity base These are the non-citrus fruity bases typified by peach, strawberry, apple, banana, melon, pineapple, and raspberry, etc. In recent years, tropical fruits are also being used to create a characteristic scent. 4.5.2.2. Spice base The spice bases have a stimulative nature characterized by clove, cinnamon, thyme, pepper, cardamom, and nutmeg. 4.5.2.3. Aldehyde base The aldehyde bases have long had a popular appeal and incorporate 7-12 carbon elements in a fatty aldehyde; they are an important group and form a characteristic constituent of the popular Chanel No. 5. 4.5.2.4. Animal base These are the musk, civet, castoreum and amber bases. Natural musk and amber, in particular, are hard to obtain and so they are mostly made by aroma chemicals.

4.6. Perfume creation The expert who creates perfumes for alcoholic fragrances and cosmetics is called a perfumer. Perfumery raw materials comprise about 500 natural aromatic raw materials and 1000 aroma chemicals which are blended to create a perfume matching the required image. In addition, the perfumer may also use generic fragrance compounds in creating a new perfume. Simple perfumes may contain a blend of 10-30 materials whereas complex sophisticated perfumes may contain 50-100 materials. In the most extreme case, more than 200 materials may be blended together to suit a particular purpose. 4.6.1.

Creation

Fig. 4.6 shows the procedure for creating a perfume for use in cosmetics. First, the product concept is developed and a plan is evolved about the perfume image by collecting technical and market information. The perfumer then uses this image to create a formula for the perfume using a combination of natural perfumes, aroma chemicals and base compounds and incorporating technical factors such as safety and stability. In concrete terms, the development conceptual methods are: (1) Create a perfume with an image using people, scenery, descriptive words (image words, sensory words). (2) Create a perfume using hints from existing perfumes or their images. (3) Create a new perfume by substituting part of a fragrance with part of another fragrance. (4) Create a perfume using the unique characteristics of new chemicals.

Cosmetics

and fragrances

111

Product Concept Technical <" Development

> Market Information Fragrance Trends, Originality

Creativity Fragrance Image

[Technical Experience] Natural Aroma Raw Materials and Aroma Chemicals

I

1

Create Perfume I

I

Fragrance Compounds Harmony Safety Stability Preference Price

Cosmetic Perfume Fig. 4.6. Creation of cosmetic perfume.

(5)

Using analysis data of fragrances such as flowers, create a perfume having an image of that fragrance. For alcoholic fragrances, the fragrance must be beautiful and sophisticated; for creams and toilet water, the fragrance must match the product image. Toothpastes require a refreshing flavor, whereas soaps and shampoos need a clean feeling. In other words, the fragrance used in each cosmetic product must match the cosmetic usage. However, there are a number of common factors involved in creating skills for fragrant products such as alcoholic fragrances, cosmetics, soaps and toothpastes. The creation of fragrances must be done in accordance with the volatilities of the raw materials to give the top note, middle note and base note (or lasting note and dry out) and there are also the side issues of the role of fragrance modifiers and fixatives. The formulation determines whether or not the perfume will be beautiful. The top note in the formulation imparts the important first impression. Usually citrus, fruity, or green notes are used for this role since they have general preference, and increase the overall freshness image. However, there is need for originality. The top notes have high volatility and there must be no residual scent after 2 h on a smelling strip. After the top note has faded, the middle note plays an important role in establishing the whole fragrance. The middle notes have medium volatility and typical examples are floral notes such as jasmine and rose, and aldehyde and spicy notes. They are the most important component of any perfume expressing its special character. When these fragrances are applied to a smelling strip, they must last for 2-6 h. Finally, as the lasting note, there are the low volatile fixatives such as oakmoss and woody notes, animal notes and balsamic notes. The lasting note must last for more than 6 h on a smelling strip. Consideration must be given to the balance between the notes, because the volatility varies with cosmetic bases used. In constructing a perfume, top notes are used in higher ratio in fresh and fruity fragrances, and lasting notes are used in higher ratio in oriental or Chypre fragrances.

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There is no fixed curriculum on training a perfume, but generally the procedure is as follows: (1) Memorize the smell and its characteristics such as volatility, strength and diffusivenes of the perfumery raw materials. (2) Memorize the accords with simple combination such as the important floral base and woody base. (3) Imitate floral notes. (4) Compose the basic types of fragrances on the market. (5) Imitate great perfumes. This process requires education by an experienced perfumer and a good laboratory; most important is studying his creative skills. 4.6.2.

Preference

The preference of a fragrance varies with sex, age, experience and culture. Generally, Japanese men and women all like floral and citrus fragrances, but there is an agedependent tendency as follows: At age 8-15, fruity notes are mostly preferred, from 1520, mint and citrus are best liked; young women from 20-24 prefer light floral and floral green fragrances. Women from 25-30 favor elegant floral aldehydic and green floral fragrances. When experience has been obtained regarding fragrance, sensual fragrances such as chypre and oriental fragrances are preferred. In comparison to Europeans, Japanese men generally prefer citrus and floral fragrances. Depending on experience and lifestyle, green, fougere and chypre fragrances become more preferred. On the other hand, fragrances used by women in the USA tend to be centered on diffusive and substantive fragrances such as oriental and white floral fragrances. American men tend to prefer oriental and chypre fragrances. However, French women have a wide range of favorite fragrances and it is difficult to say which family of fragrances are preferred most. Looking at different types of cosmetics, generally popular fragrances such as rose, jasmine, lily of the valley, and lilac are used for lotions and creams; for makeup cosmetics, powdery and sweet fragrances are commonly used but recently, floral fragrances have become more popular. Overall, there is a trend towards subtle and sophisticated fragrances. 4.6.3. Fragrance strength and perfume dosage Men and women have different preferences for the strength of a fragrance, but at the same time, the fragrance is used to appeal to the opposite sex. Some products now on the market have a relatively weak or no fragrance to meet the natural trend. Table 4.3 shows normal perfume dosages for cosmetics and toiletries. 4.6.4. Odor and color changes The fragrances used in alcoholic fragrances, cosmetics and soaps, etc., as described previously are all complex blends of materials, each of which has different types of chemi-

Cosmetics and fragrances

119

Table 4.3. Perfume dosage Product Creams Milky lotion Lotion Foundations Lipsticks Face Powders Eye Makeup Hair Tonics Hair Liquids

Perfume dosage

Product

Perfume dosage

0.05—0.2 0.03--0.2 0.001—0.05 0.05—0.5 0.03-0.3 0.02-0.2 0.01-0.1 0.5 —1.0 0.3 - 1 . 0

Hair Sprays Hair Mousses Stick, Pomade Shampoos, Rinses Soaps Cleansing Foams Bath Preparations Toothpastes Detergents

0.05--0.3 0.02--0.3 0.5 --3.0 0.2 --0.6 1.0 --1.5 0.1 --0.7 0.2 --3.0 0.7 --1.2 0.1 -^0.3

cal functional group, so it is very important to pay careful attention to preventing changes in odor and color due to compatibility problems between the fragrance and cosmetic components. Fragrance compounds are affected by oxygen, light, temperature and humidity as well as by the physical and chemical influence from cosmetic raw materials; reactions such as oxidation, polymerization, condensation, hydrolysis, etc., may harm the fragrance and change the color. Usually, most cosmetic bases are neutral pH. However, soap is alkaline whereas some hair products have oxidation and reduction properties so it is necessary to consider the choice of fragrance material used. Moreover, many perfumery raw materials are easily affected by heat and light so it is necessary to pay attention to chemical reactivity, the container and form of the packaging. 4.6.5.

Safety

Many types of natural perfumes and fragrance compounds are used in cosmetics and much research has been done so they can be used without dermatological problems occurring. At the Research Institute for Fragrance Materials (RIFM) which was established in 1966, there is a large database on items such as acute oral toxicity, acute trans-dermal toxicity, dermal sensitivity, mucous membrane sensitivity, allergenicity, phototoxicity, photoallergenicity, teratogenicity, carcinogenicity, neurotoxicity, etc., for evaluating the safety of perfumery raw materials. The International Fragrance Association (IFRA) has determined guidelines for safe use of fragrances based on these evaluation results. Cosmetic fragrances are made worldwide based on these self-regulatory guidelines (prohibited use and restricted use). On the other hand, a large amount of active research is being conducted into the phototoxicity and allergenicity of natural perfumes, as well as into explaining the reasons for such responses, and into safe materials that avoid these problems. As a result, cosmetic fragrances are now very safe.

120 New cosmetic science

References 1. Tanida, M., Kikuchi, A., Yamaguchi, H. et al.\ llnd. International Congress of Applied Psychology, Abst., p. 96, 1990. 2. Soap Perfumery Cosmet, 59 (11), 609 (1986). 3. Shibata, H., Fujiwara, R., Yokoyama, M. et al.: Int. J. of Neurosci., 245-247 (1989). 4. Fujimaki, M., Hattori, T., Hayashi, K., Aral, S., eds.: Dictionary of Perfume, Asakura Shoten, 1980. 5. Japan Fragrance Association: Perfume Encyclopedia, Asakura Shoten, 1989. 6. Okuda, O.: Perfumery Science, Hirokawa Shoten, 1967. 7. Masada, Y.: Analysis of Essential Oils by Gas Chromatography and Mass Spectrometry, Horokawa Shoten, 1968. 8. Arctander, S.: Perfume and Flavor Chemicals, Newark, NJ (USA), 1969. 9. Kurosawa, L.: Dictionaire des Parfums et des Aromes, Fragrance Journal Inc., 1984. 10. Indo, M.: Useful Perfumery Facts, Toyo Keizai Shimposha, 1975. 11. Takenaka, T.: Approach to Creative Fragrances, Fragrance Journal Inc., 1983.

5 Raw materials of cosmetics As a result of scientific developments, it is now possible to obtain a diverse range of higher-quality raw materials, including natural compounds, synthetic compounds and biosynthetic materials. Recently, the dominant trends have been disappearance of the dependency on other industries for supply of general raw materials, demand for new functions, and active design of raw materials for cosmetics matching the physiological mechanisms of the skin. The principal raw materials used to manufacture cosmetics are oily materials such as oils, fats, wax esters, and ester oils, surface active agents used for emulsifiers, solubilizing agents, etc., humectants, thickening agents, film formers, as well as polymers used as powders, ultraviolet absorbents, antioxidants, sequestering agents, coloring agents such as dyes and pigments, along with vitamins, pharmaceutical agents such as plant extracts and perfume. Cosmetics are generally used only on the skin and hair, consequently the main conditions to be considered when using and selecting the raw materials are: (1) excellent functions matching usage purpose; (2) good safety; (3) excellent oxidation stability; and (4) constant quality such as lack of smell. The raw materials must be given the above type of consideration but there are also other factors governing the choice of materials such as controls imposed by the laws of various countries (Pharmaceutical Affairs Law). In Japan, new materials that have not received approval for use in cosmetics under the Pharmaceutical Affairs Law cannot be used. To receive approval, the safety of any new materials used in a cosmetic must be confirmed. The majority of approved raw materials for cosmetics are covered by the approximately 2600 entries in the Japanese Standards of Cosmetic Ingredients and Japanese Cosmetic Ingredient Codex. These standards are based on the Cosmetic Quality Standards which govern the quality of cosmetics and establish fixed standards for the raw materials used for the purpose of raising safety; the Japanese Standards of Cosmetic Ingredients describe about 600 raw materials. In America, ingredients that are not prohibited or regulated by law are used at the discretion of the manufacturer. The following sections explain the principal raw materials used in cosmetics. However, colors and pigments, perfumes, pharmaceutical agents, and preservatives are covered elsewhere in this book and are therefore not explained here.

5.1. Oily materials Oils have the ability to dissolve fats etc. and are widely used as a component of cosmetics. Oily materials control the evaporation of moisture from the skin and are used mainly to improve the feeling on use. 121

122 New cosmetic science 5. LI.

Oils and fats

The main components of oils and fats are triglycerides of fatty acids and glycerine which are widespread in the plant and animal kingdoms. Oils are compounds that are liquid at room temperature, while fats are solid^\ Oils and fats used in cosmetics are obtained from nature but they are processed to remove smell and color, etc.; depending on the type, they may be used as hardened oils by partial or complete hydrogenation, or as types with solid fats removed by cooling. Since oils and fats are obtained either from plants and animals or from living materials, there are many types but a comparatively limited number of them are used as raw materials in cosmetics. 5.1.1.1. Olive oil This oil is pressed from the fruit of the olive tree, Olea europaea Linne. (Oleaceae). The main producing districts are the Mediterranean countries such as Spain and Italy. The constituent fatty acids in the oil are oleic acid (65-85%), as well as palmitic acid (716%) and linoleic acid (4-15%). Olive oil is used to control moisture evaporation from the skin and to enhance the feeling on use. 5.1.1.2. Camellia oil Camellia oil is obtained from the seeds of the camellia bush, Camellia japonica Linne. (Theacea). The constituent fatty acids in the oil are oleic acid (82-88%), as well as saturated fatty acids such as palmitic acid (8-10%) and linoleic acid ( 1 ^ % ) . It is used in cosmetic creams and milky lotions much the same way as olive oil. It has also been long used as hair oil. 5.1.1.3. Macadamia nut oil Macadamia nut oil is pressed from the nuts of the macadamia tree, Macadamia ternifolia in Australia. The constituent fatty acids in the oil are oleic acid (50-65%), as well as palmitoleic acid at unusually high levels (20-27%) for a plant oil. This characteristic improves the feeling on use of cosmetics and macadamia nut oil is widely used in creams, milky lotions and lipsticks^'^^. 5.1.1.4. Castor oil Castor oil is obtained from the seeds of the castor plant, Ricinus communis Linne. (Euphorbiaceae) and the main producing districts are India and Africa. The constituent fatty acids in the oil are ricinolic acid as the hydroxy acid (85-95%). In comparison to other oils, it is hydrophilic, viscous and soluble in ethanoP^. These characteristics make it useful in lipsticks and pomades, etc., as well as a dye solvent of tetrabromofluorescein. 5.7.2. Wax esters In terms of chemical composition, the wax esters are esters of higher fatty acids and higher alcohols; they are obtained from both plants and animals. These plant and animal

Raw materials of cosmetics

123

waxes have many of the same components as esters described previously but they also include free fatty acids, higher alcohols, hydrocarbons, and resins, etc. In addition, the fatty acids and higher alcohols constituting wax esters are different from fats in that they contain relatively more carbon atoms (C20-C30). Wax esters are used widely in skin care cosmetics and makeup cosmetics, to harden things like lipstick, to give a luster and to improve the feeling on use. 5.7.2.7. Carnauba wax This hard brittle wax is scraped from the leaves and leaf stems of wild or cultivated 10 m high carnauba palms, Copernicia cerifera Mart (Palmae) growing in South America, especially Brazil. It comprises esters of C20-C32 fatty acids, and C28-C34 alcohols; it has large amounts of hydroxy acid esters and has an usually high melting point for a plant waxof80-86°C. The main uses for carnauba wax are in stick cosmetics such as lipstick to improve the gloss and heat endurance. 5.7.2.2. Candelilla wax This wax is purified from the stems of the candelilla family of Euphorbiaceae plants {Euphorbia cerifera Alcocer, Euphorbia antisyphilitica Zucarrini, and Pedilanthus pavonis Boissier) growing in the deserts of northwest Mexico and Texas, etc., which are very dry and experience extreme diurnal variations in temperature. It is composed of approximately 30% C16-C34 fatty-acid esters, and 45% hydrocarbons such as hentriacontane (C31H64) with approximately 25% free alcohols such as myricyl alcohol and resins, etc. It is used mainly in stick products such as lipstick to improve gloss and heat endurance. 5.1.2.3. Jojoba oil Jojoba oil is a liquid wax ester extracted from the seeds of the wild jojoba plant, Simmondsia chinensis and Simmondsia californica Nuttall (Euphorbiaceae) growing in the high dry deserts of the American south (Arizona, California) and northern Mexico. The main components are esters of unsaturated higher alcohols (11-eicosen-l-ol and 13dococen-1-ol) as well as unsaturated fatty acids (11-eicosenoic acid and oleic acid)^). In recent years, large amounts have become available from jojoba plantations. Jojoba oil has excellent stability for autooxidation and superior feeling on use giving it a pleasant touch to the skin so it is used extensively in creams, milky lotions, lipsticks, etc. 5.1.2.4. Beeswax Bees wax is obtained from hives of the Oriental honeybee. Apis indica Radoszkowski (Apidae) and European honeybee, Apis mellifera L. After the honey is removed from the hive, the wax is put in hot water to separate the bees wax as a yellow or pale yellow solid. The composition of bees wax from Oriental and European bees is slightly different but the main components are esters of higher fatty acids and higher alcohols with some free fatty acids and hydrocarbons. The main components of bees wax from Oriental honeybees is ceryl 16-hydroxypalmitate (Ci5H3o(OH)COOC26H53) and ceryl palmitate

124

New cosmetic science

(C15H31COOC26H53) whereas the main component of bees wax from the European honeybee is miricyl palmitate (Ci5H3iCOOC3iH53)6). Bees wax is used mainly in creams and stick-type products such as lipstick and hair stick. 5.1.2.5. Lanolin Lanolin is a fatty compound manufactured from the fleece of the domesticated sheep, Ovies aries Linne. (Bovidae). It forms a bright yellow paste. The main components of lanolin are mixtures of higher fatty acids, sterols and esters of higher alcohols. The constituents of higher fatty acids are a complex mixture of mainly:

Anteiso fatty acids

ISO fatty acids

'

' > CH(CH2)„C00H (w = 4-26)

CH

\ ' ) CH (CHJ^COOH

(^-6-24)

The sterols and higher alcohol components are mainly cholesterol, and isocholesterol but also include C13 to C33 higher alcohols. Lanolin has an affinity for skin and is quite sticky as well as being physically hygroscopic so it is used in creams and lipsticks. 5.1.3.

Hydrocarbons

Hydrocarbons used as raw materials in cosmetics are normally saturated and have carbon chains longer than C15. In the main, they are liquid paraffins, solid paraffins and petrolatum obtained from petrochemical resources, as well as squalane obtained by hydrogenating squalene obtained from both animals and plants. 5.1.3.1. Liquid parajfins Liquid paraffins are manufactured by removing solid paraffins from the petroleum fraction obtained above 300°C. They are a complex mixture of saturated hydrocarbons with 15-30 carbons and are liquid at room temperature. They are easily manufactured and are colorless, and odorless. They are chemically inactive and form emulsions easily. They are used in skin care cosmetics such as creams and milky lotions and to control moisture loss from the skin and improve the feeling on use. 5.1.3.2. Paraffin Paraffin is a colorless or white translucent solid (melting point 50-70°C) obtained either by vacuum distillation or solvent extraction of the final fraction remaining in petroleum distillation. It is composed mainly of straight hydrocarbon chains but commonly includes 2-3% branched hydrocarbons. The carbon number ranges from C16-C40 with C20C30 being most common.

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125

Like liquid paraffins, paraffin is colorless, odorless and chemically inactive and is used widely in creams and lipsticks, etc. 5.1.3.3. Petrolatum The light grease obtained when waxes are removed by solvent extraction from the fraction remaining after vacuum distillation of petroleum is called petrolatum or vaseline. The main component is C24-C34 hydrocarbons in a noncrystalline form. Petrolatum is not a simple mixture of liquid paraffins and paraffin; it is believed to be a colloid composed of external phase solid paraffin and internal phase liquid paraffins. Like liquid paraffin, petrolatum is odorless, chemically inactive and has high adhesive power so it is used widely in creams and lipsticks, etc. 5.1.3.4. Ceresin Ceresin is refined ozocerite and it is mainly composed of C29-C35 straight hydrocarbons although it sometimes includes isoparaffin. The molecular weight is higher than that of paraffin and the specific gravity, hardness and melting point (61-95°C), etc., are high. It is used as a hardening agent in lipsticks, hair sticks, etc. 5.7.5.5. Microcrystalline wax Microcrystalline wax^^ is a solid obtained by extracting the oil from petrolatum. It is a complex mixture composed mainly of C31-C70 isoparaffins. It has a microcrystalline structure, high adhesive power, good extensibility, is not susceptible to low temperatures, and a high melting point (60-85°C). When mixed with other waxes, it suppresses crystal formation making it useful in lipsticks and creams. 5.1.3.6. Squalane Squalene occurs in large amounts in various species of deep sea sharks and it is also found in olive oil, etc. Squalane (2,6,10,15,19,23-hexamethyltetracosan, C30H62) is obtained by hydrogenating squalene; it is liquid at room temperature. Squalane is a very safe, chemically inactive oil used widely in skin care cosmetics such as creams and milky lotions, etc. 5.1.4. Higher fatty acids Fatty acids are compounds with the general chemical formula RCOOH where R is either a saturated alkyl group or an unsaturated alkenyl group. They include various esters in natural fats and oils. Fatty acids in various plant and animal fats have many straight chain carbon molecules and are almost all even numbered. However, progress in petrochemical synthesis has led to the development of side chain and odd number fatty acids8). Fatty acids are mixed with fats and oils, waxes and hydrocarbon compounds for use as raw materials of cosmetics. They are also used with caustic potash and triethanolamines, etc., as emulsifiers for the production of soaps. 5.1.4.1. Laurie acid: CHs(CH2)ioCOOH Laurie acid is obtained by distillation of the fatty acid mixture obtained by saponifica-

126 New cosmetic science

tion of coconut and palm nut oils. Soap obtained by mixing lauric acid with sodium hydroxide and triethanolamine has high solubility in water and lathering qualities making it useful for cosmetic soaps and cleansing preparations. 5.1.4.2. Myristicacid: CHs(CH2)i2COOH Myristic acid is obtained by distillation of the fatty acid mixture obtained by saponification of palm nut oil. It is not used directly to any great extent in cosmetics but myristic acid soap has excellent lathering qualities and cleansing power so it is used in cleansing preparations. 5.1.4.3. Palmitic acid: CHi(CH2)i4COOH Palmitic acid is obtained by saponification of palm oil, etc. It is used as a oily base in creams and milky lotions, etc. 5.1.4.4. Stearic acid: CH3(CH2)i6COOH There are two manufacturing processes for stearic acid: (1) production by removing liquid acids (mainly oleic acid) from the fatty acids obtained by saponification of fat from beef tallow, and (2) production by distillation of fatty acids obtained by saponification of hydrogenated soy bean or cotton seed oil. Stearic acid obtained by the former method contains quite a lot of palmitic acid, whereas the latter method produces stearic acid of high purity and high melting point^^. Stearic acid is used in creams to modify the cream consistency and hardness; it is common in creams, lotions and lipsticks, etc. 5.1.4.5. Isostearic acid The Cig saturated fatty acid with a branched structure is called isostearic acid. Isostearic acid is formed by hydrogenation of the unsaturated fatty acid byproduct when synthesizing dimer acid from oleic acid^\ It can also be produced by the Guerbet method and by hydrogenating and oxidizing the aldol condensate of nonyl aldehyde. Isostearic acid is a liquid ingredient with a lower melting point than saturated fatty acids like stearic acid and palmitic acid and it is less easily oxidized than unsaturated fatty acids such as oleic acid. It is used as an oily raw material and the salts such as triethanolamine are used as emulsifiers. 5.7.5. Higher alcohols Higher alcohol is the name given to monovalent alcohols with six or more carbon atoms. They are broadly grouped into alcohols produced from natural oils and fats and alcohols produced from petrochemicals^^^ The higher alcohols are used both as oily raw materials and as emulsion stabilizers in emulsified products. 5.7.5.7. Cetyl alcohol^^\' CHs(CH2)i50H Cetyl alcohol is also called cetanol and it is produced by fractional distillation of the alcohols obtained by saponification of whale oil. It can also be produced by fractional distillation after reduction of fat from beef tallow, as well as by the Ziegler reaction.

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127

Cetyl alcohol is a white waxy solid with a hydroxyl group so it does not have emulsifying properties itself but is used as an emulsion stabilizer in emulsified products such as creams and milky lotions. 5.7.5.2. Stearyl alcohol: CH3(CH2)i70H Stearyl alcohol is manufactured by the same method as cetyl alcohol. It is a white waxy solid. It is used both as an emulsion stabilizer in emulsified products such as creams and milky lotions, and in stick products such as lipsticks. 5.1.5.3. Isostearyl alcohol Isostearyl alcohol is the name given to the Cig saturated alcohol with a branched structure. It is obtained by chemical synthesis using the Guerbet reaction, the oxo reaction and by aldol condensation, etc. In recent years, isostearyl alcohol produced by reduction of isostearic acid formed by hydrogenation of unsaturated fatty acid byproducts of dimer acid production has appeared on the market. Isostearyl alcohol is a liquid ingredient with excellent heat and oxidation stability; it is used as an oily raw material. 5.1.5.4. 2-Octyl dodecanol 2-Octyl dodecanol is synthesized by the Guerbet reaction and by aldol condensation. It is a colorless transparent liquid with almost no smell and a low freezing point due to its branched structure which is unusual in higher alcohols. It has good feeling on use so it is used as an oily raw material. 5.1,6. Esters Esters are obtained by dehydration of acids and alcohols. Typical acids are fatty acids, polybasic acids, and hydroxy acids; typical alcohols are lower and higher alcohols, and polyhydric alcohols. Various esters are produced from different combinations of acids and alcohols but relatively few are used in cosmetics. Esters have different properties depending on the structure, molecular weight, etc., and they are used as emollients, dye solvents and clouding agents, etc. 5.1.6.1. Isopropyl myristate Isopropyl myristate is a colorless transparent liquid produced by esterification of myristic acid and isopropanol under sulfuric acids followed by distillation and deodorization. It is used as a miscible agent for oil and water mixtures, as a solvent for dyes, etc., and in milky lotions, makeup products and hair cosmetics. 5.1.6.2. 2-Octyldodecyl myristate 2-Octyldodecyl myristate is an ester of myristic acid and 2-octyldodecanol obtained by the Guerbet reaction. It has a low melting point and is very resistant to hydrolysis. It is used to control moisture loss from the skin as well as to improve the feeling on use.

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New cosmetic science

5.1.6.3. Cetyl 2-ethyl hexanoate Cetyl 2-ethyl hexanoate is an ester of cetanol and 2-ethylhexanoic acid. It has a low viscosity and high resistance to hydrolysis and oxidation, as well as a good feeling on use so, it is used widely in creams, milky lotions, etc. 5.1.6.4. Di-isostearyl malate Di-isostearyl malate is an ester of isostearyl alcohol and malic acid. It is a thick transparent liquid in spite of its high molecular weight. The isostearyl alcohol used in this production is composed mainly of 5,7,7-trimethyl-2-(l,3,3-trimethylbutyl) octyl alcohol. Di-isostearyl malate is very resistant to hydrolysis and oxidation. It has a relatively low stickiness in spite of its high viscosity. It is excellent as a dispersant and miscible agent for pigments, and also as a miscibilizer for polarized-nonpolarized oily mixtures such as castor oil and liquid paraffin. As a result of these characteristics it is used in stick products such as lipstick, as well as in foundations and creams. 5.7.7.

Silicones

Silicones is the name given to organic silicon compounds containing the siloxane chain (-Si-O-Si-). A typical example is methylpolysiloxane in which all the organic groups are methyl groups. The silicones are available in a wide range of viscosities. Silicones are highly hygroscopic and they have none of the sticky feeling found in hydrocarbons so they have good feeling on use making them suitable for a wide range of applications on skin and hair. Two typical silicones are described below.^^-^^^ 5.1.7.1. Dimethylpolysiloxane

CH3

I-

CHa-Si-O

I

CH3

CH3

I -Si-0 I CHa

CH3

I

-Si-CHa

I

CH3

Dimethylpolysiloxane is a colorless transparent oil. There are low-viscosity oils and pastes depending on molecular weight. Since the solubility of other materials worsens with increasing molecular weight, such low-viscosity materials have many applications. The high hygroscopy makes dimethylpolysiloxane useful in skin cosmetics for resisting fade of make up caused by water and perspiration. Dimethylpolysiloxane reduces the stickiness of oils giving a light feeling on use; it is also employed in a wide range of skin and hair products due to its spreadability. 5.1.7.2. Methylphenylpolysiloxane Methylphenylpolysiloxane has a structure in which some of the methyl groups of dimethylpolysiloxane are replaced by phenyl groups. It is characterized by complete insolubility in ethanol. However, it has good compatibility in other oils and is used in a wide range of products.

Raw materials of cosmetics

129

5.7.8. Others Polyoxypropylene adducts of the lower alcohols like butanol are used in liquid hair dressings. The adducts are obtained by addition of propylene oxide to lower alcohols with an alkaline catalyst such as sodium hydroxide. Comparatively low molecular weight adducts are soluble in ethanol and liquid at room temperature. They are used in liquid hair dressings due to their ability to keep hair neat and tidy.

5.2. Surface active agents The solute in a solution can be adsorped to a gas-liquid, liquid-liquid, or liquid-solid surface; these remarkable changes in the properties of surfaces are called surface activity and so-called surface active agents are materials demonstrating unusual surface activity. This surface activity is exploited in emulsification, solubilization, permeation, wetting, dispersion, cleansing, as well as in moisturizing, sterilization, lubrication, electrostatic prevention, softening, antifoaming, etc. There are a very large number of surface active agents but they share a similar molecular structure; the molecule has a part with an affinity for oils (lipophilic or hydrophobic) and a part that has an affinity for water (hydrophilic). The combination and balance of these causes various changes in the properties of the interface or surface. Surface active agents (surfactants) are classified in various ways according to chemical structure, synthesis method, properties and uses, etc. However, generally the major classification is based on the ionic dissociation when dissolved in water. Dissociating types are classified as anionic, cationic and amphoteric types, whereas non-dissociating types are classified as non-ionic. The following section describes some typical surfactants based on this classification as well as some polymeric and natural surfactants. 5.2.1. Anionic

surfactants

When anionic surfactants are dissolved in the water, the hydrophilic base dissociates into anions; anionic surfactants are classified broadly into carbonate, sulfate ester, sulfonate and phosphate ester types. Generally, a soluble salt such as sodium, potassium, or triethanolamine is used as the hydrophilic part. A great many compounds can be used as the lipophilic part but generally alkyl or branched alkyl groups are used. Consequently, the molecular structure incorporates acid-amide bonds, ester bonds and ether bonds, etc. Typical anionic surfactants are described below. 5.2.7.7. Soap: RCOOM [R: Cy_2i> M: Na, K, N(CH2CH20H)s] Soaps are obtained by hot saponification of an alkaline aqueous solution of fats such as tallow fats, coconut oil and palm nut oil; the reaction between higher fatty acids and alkali creates a so-called neutral soap. Soaps are widely used in cosmetics as cleansing creams and shaving creams due to their excellent cleansing and lathering properties.

130 New cosmetic science

5.2.1.2. Alkyl sulfate: ROSOjM Alkyl sulfates are obtained by reacting fatty alcohols with chlorosulfonic acid, sulfuric anhydride, or fuming sulfuric acid, etc. and then neutralizing. They are used in such cosmetic products as shampoos and dentifrices due to their excellent cleansing and lathering properties. 5.2.1.3. Polyoxyethylene alkyl ether sulfate: RO(CH2CH20)^SOsM Polyoxyethylene alkyl ether sulfate is obtained by polymerizing oxyethylene and a fattyacid alcohol by addition polymerization followed by sulfonation and neutralizing with an alkali. The solubility is good and it is used widely in shampoos, etc., due to its excellent cleansing and lathering properties. The alkyl group is C12-C14 and two or three moles of oxyethylene give improved lathering and cleansing. 5.2.1.4. Acyl N-methyl taurate R • CONCH2CH2SO3M

I

CH3

Acyl A^-methyl taurate is obtained by a dehydrochloric acid reaction under alkaline conditions of an acyl chloride and methyl tauric acid, or by a dehydration reaction between a fatty acid and methyl tauric acid. It is very safe and usable in wide pH range and in hard water as well as good lathering properties so it is widely used in cosmetic cleansing creams, shampoos, etc. 5.2.1.5. Alkylether phosphate KOxp^O

RO^^^O

RO^^^O

MO"" ^OM

RO"" ^OM

RO^ ^ OR

Monoalkyl ether phosphate Dialkyl ether phosphate

Trialkyl ether phosphate

Alkylether phosphate is obtained by phosphoric esterification of a fatty alcohol or the terminal group of the polyoxyethylene derivative and then subsequent neutralization. The product on the market is actually a mixture of the mono-, di- and trialkyl ether phosphate. The monoalkyl ether phosphate is soluble in water but the trialkyl ether phosphate is only slightly soluble so this surfactant must be selected according to product usage. Alkylether phosphate is used in cosmetic cleansing creams and shampoos. 5.2.1.6. N-Acylamino acid salts Since amino acids have both amino and carboxyl groups in the molecule, it is possible to obtain surface activity by introducing a lipophilic material. A typical substance is A''acylamino acid salt which is obtained from a reaction with a fatty acid. Examples are NAcylsarcosinate RCON(CH3)CH2COOM, A^-acyl-A^-methyl-/?-alaninate RCONCCHg)CH2CH2COOM, and A^-Acylglutamate RCONHCH(COOM)CH2CH2COOM.

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Since A^-acylglutamate has two carboxyl groups in the molecule, it is possible to obtain surfactants containing mono- or di- salt with any ratio. This A^-acylglutamate is used in shampoos, cleansing creams and dentifrices. 5.2.2. Cationic

surfactants

When a cationic surfactant is dissolved in water, the hydrophilic part dissociates as cations. Since this is the reverse of anionic surfactants, these materials are called invert soaps. Cationic surfactants have normal surface activities such as cleansing, emulsification and solubilizing, but they are especially well adsorbed onto smooth hair and also have anti-static properties, so they are used in hair treatments. Cationic surfactants are classified from their structure into quaternary ammonium salts and amine derivatives but the amine derivatives are hardly used in cosmetics and are omitted from this discussion. 5.2.2.7. Alkyltrimethyl ammonium chloride: (RN-^(CHj)j)Cl~ R: Cj^C22 Alkyltrimethyl ammonium chloride is obtained as the quaternary ammonium salt via the alkyldimethyl amine produced by reacting an alkyl amine with methyl chloride in an alkaline medium under pressure. 5.2.2.2. Dialkyl dimethyl ammonium chloride: (R'R'N^(CHj)2)Cl~ R: Ci^C22 This compound is known to have smoothing properties on tangled hair and also has antistatic properties, so it is used in hair rinses. It has poor bactericidal activities but low toxicity and skin irritability. 5.2.2.3. Benzalkonium chloride CH3

^

^CH-N^-R

ci-

CR:C.3~M]

CH3

This compound is well known as an invert soap and it is generally used as a bactericide particularly in shampoos, hair tonics and hair rinses. 5.2.3. Amphoteric

surfactants

Amphoteric surfactants have both cationic and anionic functional groups coexisting in the molecule. Generally, under alkaline conditions, they dissociate into anions, and under acid conditions, into cations. For this reason, they can be used to make up for the deficiencies of ionic surfactants. In comparison to ionic surfactants, they have very low skin irritability and toxicity and many amphoteric surfactants have good cleansing, bactericidal, bacteriostatic, lathering, and softening properties. These properties are used to advantage in shampoos and baby products; in addition, they are used in aerosols due to their ability to stabilize the lather and promote its formation.

132 New cosmetic science 5.2.3J. Alkyl dimethylaminoacetic acid betaine: RN^(CHj)2CH2COO- R: Cj2-C]8 As shown by the above structure, the surface activity of this compound is due to the combination of a cationic quaternary ammonium salt and an anionic carboxyl group. A characteristic feature of alkyl dimethylaminoacetic acid betaine is its good solubilization ability and stability across a wide pH range. In cosmetics, it is used in shampoos and hair rinses due to its softening, anti-static and wetting properties. 5.2.3.2. Alkyl amidopropyl dimethylaminoacetic acid betaine: RCOONH(CH2)3N^. (CHs)2CH2COOThis compound is also used in shampoos, etc., due to its softening, anti-static and wetting properties. 5.2.3.3. 2-Alkyl-N-carboxymethyl'N-hydroxyethylimidazolinium betaine R-cr^

I

^N^-CH2

/ \

-OCOCH2

CH2CH2OH

The above structural diagram shows that this compound has an imidazolin ring and it has recently been elucidated that the ring is open rather than closed^^^ Like other amphoteric surfactants, this compound has very low toxicity, skin irritability and mucous-membrane irritability and also makes the hair softer and more glossy. In addition, it is able to tolerate hard water, making it ideal for use in hair cosmetics, creams and emulsions, etc. 5.2.4. Non-ionic

surfactants

Non-ionic surfactants are unlike ionic and amphoteric surfactants because they do not dissociate into ions. Their surface activity is due to the presence of -OH, - 0 - , -CONH-, and -COOR groups in the molecule. Owing to this structure, they are generally classified into polyoxyethylene chains having hydrophilic groups, and compounds with hydroxyl groups. In other words, the lipophilic groups are broadly the same as the ionic surfactants, but there are many possible combinations of types ranging from those with low water solubility, due to the length of the polyoxyethylene chain containing the hydrophilic groups, to those with good water solubility due to the number of hydroxyl groups. These combinations cause large differences in properties such as degree of solubility, wetting, penetration power, emulsification and solubilization, etc., of nonionic surfactants due to the different balances (HLB) of lipophilic and hydrophilic groups. 5.2.4.1. Polyoxyethylene type non-ionic surfactants RO(CH2CH20)„H RCOO(CH2CH20)„H RC6H60(CH2CH20)„H

R: C12-C24 R: C12-C18 R: C8-C9

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As the formulae show, these compounds are obtained by addition polymerization of ethylene oxide at normal or elevated pressures in an alkaline medium. The lipophilic groups are typically a higher fatty alcohol, a higher fatty acid, an alkyl phenyl, an alkylolamide or a sorbitan higher fatty-acid ester, etc. Since they are obtained by addition polymerization of ethylene oxide, normally, various types with a degree of polymerization are obtained rather than simple compositions. The solubilization of these surfactants in water can be evaluated by measuring the clouding point. If the lipophilic group is the same, the clouding point becomes higher as the length of the polyoxyethylene chain increases and they become more hydrophilic. Since these types of surfactants have excellent emulsifying and solubilizing abilities, these are used as emulsifiers in creams and milky lotions, and as solubilizers for perfumes and pharmaceutical agents, etc., in lotion. 5.2.4.2. Polyhydric alcohol ester type non-ionic surfactants These surfactants are produced by converting fatty acid esters of some of the hydroxyl groups of polyhydric alcohols, starting from glycerin, to fatty-acid esters and leaving the residual hydroxyl groups as hydrophilic groups. For example, monoglycerides are produced by esterification; they can also be produced by ester conversion from fats and glycerin. The best polyhydric alcohols to use are glycerin and trimethylol propane with three hydroxyl groups, pentaerythritol and sorbitan with four hydroxyl groups, sorbitol with six hydroxyl groups, and sucrose with eight hydroxyl groups. They can also be synthesized to compounds with several ester bonds from monoesters using the abovedescribed reaction from polyglycerin and raffinose, etc., with even more hydroxyl groups. Typical examples in this group are mono or diglycerides, sorbitan higher fattyacid esters, and sucrose higher fatty-acid esters, etc. Most of these types are hydrophilic to some extent and form emulsions in water; monoglycerides are combined with hydrophilic surfactants and used in cosmetics. Moreover, several HLB type non-ionic surfactants can be produced by addition polymerization of appropriate ethylene oxide to the residual hydroxyl groups. For example, such surfactants can be produced by addition polymerization of appropriate ethylene oxide to the residual hydroxyl groups of the sorbitan higher fatty-acid monoester and hardening with natural castor oil as well as by ethylene oxide addition. These surfactants show good emulsifying and solubilizing ability so they are widely used in skin care cosmetics. 5.2.4.3. Ethyleneoxide-propyleneoxide block polymers CH3

HO (CH2 CH2O). (CH CH^On (CH2 CH2O), H (m + n + m = 20—80, n = 15—50)

Ethyleneoxide-propyleneoxide block polymers contain both lipophilic groups glycol and hydrophilic groups from polyethylene glycol, so various surfactants having different HLBs can be obtained by freely changing m and n in the above chemical formula. These compounds have a comparatively larger molecule than other surfactants and are characterized by low skin irritation. They are marketed under the brand name Pluronic and are used widely.

134 New cosmetic science

5.2,5. Other surfactants 5.2.5.1. Polymeric surfactants Many early surfactants contained about 10-18 carbon atoms as the lipophilic group and had a molecular weight of about 300. If ethylene oxide propyleneoxide block polymers are combined with many polyoxyethylene, it is possible to obtain a molecule with a weight of 1000-2000 but normally the molecular weight is less than 1000. Based on this, polymeric surfactants could be described as surfactants with a high molecular weight. For example, polyvinyl alcohol can be made into fiber and film but when it is used for the action of emulsification or coagulation, it could easily be described as a polymeric surfactant. Based on this concept, sodium alginate, starch derivatives, and tragacanth gum, etc., can be used as emulsifiers, flocculants and dispersants. 5.2.5.2. Natural surfactants Lecithin is a well-known natural surfactant combining the anionic groups of phosphate esters with the cationic groups of quaternary ammonium salts. Lecithin is obtained from soy beans and egg yolks and the main components are phosphatidyl serine, phosphatidyl ethanolamine, phosphatidyl choline. In cosmetic applications, lecithin is used in milky lotions and creams because it has a refreshing feeling on use and softening properties. Recently, lecithin has been used to form liposomes which have a bilayer membrane. Many other natural surfactants have long been known and used including lanolin, cholesterol and saponin.

5.3. Humectants Maintaining a young-looking skin is closely connected with moisture content^^'^^^ One of the most important functions of cosmetics is maintaining skin moisture^^^. The keratin layer of the skin contains natural moisturizing factors^^-^^^ (NMF) with hydrophilic moisture absorbing compounds; NMFs are known to play an important role in skin moisturizing (Table 5.1). It is believed that the sodium salt of sodium pyrrolidonecarboxylate is the most important factor in NMF^^'^^^ NMF is not the only important factor in considering skin moisture; it is also important to consider preventing loss by bonding or surrounding, the presence of oils such as intercellular lipids and sebum controlling moisture evaporation, and holding water, the presence of mucopolysaccharides in the dermis. Cosmetics should be able to mimic this natural moisture retention mechanism. Humectants are water soluble materials with a high water absorption and they are a very important component in the aqueous phase of cosmetics. A wide variety of humectants are used in cosmetics including polyhydric alcohols like glycerin, propylene glycol, sorbitol, and including the main component of NMF, pyrrolidonecarbonate and lactates. Recent advances in biosynthesis technology has also permitted production and use of large amounts of sodium hyaluronate. As described previously, humectants play an important role in cosmetics but at the same time they also work to maintain the moisture content and stabilize the cosmetic itself. In addition, they also have bacteriostatic and fixative activities.

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Table 5.1. Composition of NMFi^,^^) Amino acids PCA(pyrrolidone carboxylic acid) Lactates Urea NH3, uric acid, glucosamine, creatinine Citrates Na 5%, K 4%, Ca 1.5%, Mg 1.5%, PO4 0.5%, CI 6% Sucrose, organic acids, peptides, other materials

40% 12% 12% 7% 1.5% 0.5% 18.5% 8.5%

(O.K. Jacobi : Proc. Sci. Sec. of Toilet Goods Assoc, 31, 22, 1959.) (H.W. Spiet, G. Pascher : Hautarzt, 7, 2, 1956.)

The main requirements of a humectant are listed below: (1) must have appropriate water absorption ability (2) must maintain water absorption ability (3) water absorption must not be influenced by changing environmental conditions (temperature, humidity, etc.) (4) water absorption ability must maintain moisture in skin (5) must have lowest possible volatility (6) must have good miscibility with other constituents (7) must have lowest possible freezing point (8) viscosity must match usage and feel good on skin (9) must be safe (10) must be as colorless, odorless and tasteless as possible In addition to having water absorption and moisturizing properties over a wide range of humidities, humectants must have densities matching the system they are used in. Even when the humectant is used incorrectly, the correct functions must still be maintained and reverse effects should not be possible. 5.3.1.

Glycerin CH2OH CHOH

I

CH2OH

Glycerin has long been used as a humectant and it is still widely used even today. It is obtained as a byproduct in manufacturing soap or fatty acids from plant and animal fats and oils. When dehydrated and deodorized, it is a colorless, odorless liquid. 5.3.2. Propylene glycol CH3

I

CHOH

I

CH2OH

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The common form is 1,2-propylene glycol. Although it looks and feels much like glycerin and is colorless and odorless, it has a better feeling on use due to its lower viscosity than glycerin. 5.3.3. 13-Butylene glycol:

CHsCH(OH)CH2CH20H

1,3-Butylene glycol is obtained by hydrogenation of the aldol condensate of acetoaldehyde as a colorless, odorless liquid. It is very safe and is used in creams and milky lotions, etc. 5.3.4. Polyethylene glycol:

HO(CH2CH20),H

Polyethylene glycol is obtained by adding ethylene oxide to water or ethylene glycol under alkaline conditions. It is not a uniformly simple compound but is a mixture polymer with various degrees of polymerization. It is a liquid at normal temperatures with an average molecular weight ranging from 200 to 600; semi-solid forms have increasing molecular weights ranging from 1000, 1500, 4000 to 6000. Generally, polyethylene glycol is colorless and odorless and its water absorption ability decreases with increasing molecular weight. It is used in creams, milky lotions, etc. 5.3.5.

Sorbitol CH2OH

I

(CH0H)4

I

CH2OH

This sugar alcohoP^^ is contained in the juice of apples and peaches, and is a white odorless solid. It is obtained by reduction of glucose. In comparison to the previously described humectants, it has lower hygroscopic property and it has a humectant effect at low humidity. It is used in creams, milky lotions, toothpastes, etc. 5.3.6. Sodium lactate:

CH^CHiOHjCOONa

Lactates are an important group of natural humectants occurring in NMF along with PC A (pyrrolidonecarboxylate). They have a higher water absorption ability than the lower-alcohol types. 5.3.7. Sodium

2-pyrrolidone-5-carboxylate CH2~CH2

0 ^ ^N^\ ^COONa H

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Table 5.2. Water absorption ability of sodium 2-pyrrolidone-5-carboxylate^^^ Compound Pyrrolidone carboxylic acid Sodium pyrrolidone carboxylate Gylcerol (comparison)

31% RH

58% RH

<1 20 13

<1 61 35

(K. Ladem, R. Spitzer : J. Soc Cosmet. Chem., 18, 351, 1967.)

Sodium 2-pyrrolidone-5-carboxylate is an important humectant component of NMF. It is the sodium salt of 2-pyrrolidine-5-carboxylate manufactured by dehydration of glutamic acid and forms an odorless solid. It demonstrates excellent hygroscopic and humectant effects and these properties have been achieved with a salt form (Table 5.2). 5,3.8. Sodium

hyaluronate

Hyaluronic acid is a type of mucopolysaccharide formed by cross-bonding between A^acetylglucosamine and gluconic acid. It is widely found in connective tissues of mammals as chondroitin sulfate, etc. In connective tissues, its function is to maintain water in the intercellular spaces and also to maintain the cells in a jelly matrix. In skin, it is believed to maintain smoothness and flexibility and to prevent external mechanical injury and bacterial infection. When examining the distribution of acidic mucopolysaccahrides in the different parts of the skin, more hyaluronic acid exists than chondroitin sulfate and heparin in the epidermis and dermis. Having moisturizing properties, hyaluronic acid makes the skin feel nice and moist; it is said that skin lacking moisture develops wrinkles due to the shortage of moisturizing hyalouronic acid in the subdermal connective tissues. Hyaluronic acid was extracted from the cockscomb of domestic fowls, but its extremely high price greatly limited use until recent development of production by microbiological techniques provided a relatively low-cost source^^'^^^^. Generally, hyaluronic acid is marketed as sodium hyaluronate, a white water-soluble powder. Properties like viscosity and humectance vary with the molecular weight. The water evaporation constant of a 0.1% aqueous solution of sodium hyaluronate at 25°C and 50% relative humidity falls with increasing molecular weight but stabilizes at molecular weights above about 800,000^^). In addition, unlike other humectants, sodium hyaluranate is almost unaffected by environmental humidity (Fig. 5.1).

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100

B 03

50

•5

q U)

J

Iff

/ f c t t H M

1 I I I I I

Moisture absorbance/^ Relative humidity 33% Temperature

Fig. 5-1. Comparison of Moisture Absorbance of Humectants 1^^^ Sodium pyrrolidone carboxylate f:-:':':'| Glycerine I I Sorbitol \IW\W\ Sodium hyaluronate Fig. 5.1. Comparison of moisture absorbance of humectants.

5.4. Polymers Polymers^'^^^) used as cosmetic raw materials are basically classified according to usage. They are mainly used as thickening agents, film formers and resinous powders. In addition, some polymers are used as humectants and surfactants. This section describes only thickening agents and film formers; the humectants, surfactants and resinous powders are described in their respective sections. 5.4.L

Thickening agents

Thickening agents are used to adjust the viscosity of products to make them easy-to-use as well as to maintain the product stability. For example, they are used to ensure the stability of milky lotions and liquid foundations by preventing the separation of emulsified particles and powders. Usually, water-soluble polymers are used as thickening agents. Table 5.3 shows the major classification based on their origin. They are classified into natural polymers, semi-synthetic polymers (natural polymers modified by reaction) and synthetic polymers. However, in the past, natural polymers formed the mainstream led by natural gums. Problems with securing stable supplies coupled with problems such as variations in viscosity and microbial contamination led to a change to synthetic and semi-synthetic substitutes. Currently, synthetic thickening agents are in the majority. Thickening agents have a great effect on the feeling on use

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Table 5.3. Classification of water-soluble polymers

Watersoluble polymer

-Guar gum, Locast bean gum, I—Vegetable (mucopolysaccharides) Quince seed gum, Carrageenan, Galactan, Gum Arabic, Tragacanth gum. Pectin, Man-Natural polymernan, Starch -Xanthan gum, Dextran, Suc-Microbial(mucopolysaccharides) cinoglucan, Hyaluronic acid -Gelatin, Casein, Albumin, Col-Animal lagen (proteins) Methyl cellulose, Ethyl celluI—Celluloses -Organic — lose, Hydroxyethyl cellulose, Hydroxypropyl cellulose, Carboxymethyl cellulose, Methylhydroxypropyl cellulose -Starches Soluble starches, Carboxymeth-Semi-syntheticpolymer yl starch. Methyl starch I—Alginates Propyleneglycol ester alginate. Alginates '—Other mucopolysaccharide derivatives Vinyls Polyvinyl alcohol. Polyvinyl pyrrolidone, Polyvinylmethyl ether, Carboxyvinyl polymer. -Synthetic polymerSodium polyacrylate L-Other-

-Inorganic-

-Polyethylene oxide. Ethylene oxide-propylene oxide copolymers -Bentonite, Laponite, Silicate powders. Colloidal alumina

of cosmetics, and various water-soluble polymers are in widespread use according to purpose. 5.4.1.1. Quince seed gum Quince seed gum is a natural gum obtained from the seeds of the quince tree growing in Europe and S. Asia. It is an acidic polysaccharide composed of L-arabinose, D-xylose, glucose, galactose, and uronic acid. To extract it, quince seeds are soaked in 20 times their weight of water (approx. 60°C) and left to soak overnight, stirring occasionally, and then filtered. The seeds are then put into a tank and the procedure is repeated. A liquid of the right viscosity is produced by mixing these liquids. This viscous liquid has a characteristic non-sticky smooth feeling. It is easily contaminated by microbes so it must either be sterilized or a preservative must be used. 5.4.1.2. Xanthan gum Xanthan gum is a natural gum obtained by fermentation of glucose with Xanthomonas campestris. It is an acidic polysaccharide composed of D-glucose, D-mannose, and D-

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glucronic acid. It has excellent usage characteristics due to low temperature dependence and stability over a wide pH range. 5.4.1.3. Sodium carboxymethyl cellulose Sodium carboxymethyl cellulose is a semi-synthetic polymer obtained by partial substitution of the hydroxyl groups in cellulose with -0CH2C00Na groups and dissolution in water. It is a transparent viscous liquid with protective colloidal and emulsification stability making it useful in creams, milky lotion and shampoos, etc. 5.4.1.4. Carboxyvinyl polymer Carboxy vinyl polymer is synthetic aery late polymer with carboxy 1 groups. It is an aqueous liquid with remarkable viscosity at neutral pH (by NaOH, KOH, triethanol amine). The quality is very stable and there is almost no change in viscosity over time or with temperature; it is much less easily contaminated by bacteria, etc., than natural gums, so it is widely used as a thickening agent. 5.4.2. Film formers As shown in Table 5.4, film formers are found in a wide range of products. Film formers are classified into water-and alcohol-soluble types according to solubility, as well as into aqueous-emulsion and non-aqueous soluble types. Packs are made by usage of film forming ability after vaporizing the water from an aqueous solution of polyvinyl alcohol. Hair sprays and hair setting lotion use polymers dissolved in water or alcohol to form a film which sets the hair. Although the polymers in shampoos and rinses do not really have a film forming function, cationic polymers are used to improve the feeling on use. Eye liners and mascara contain an aqueous polymer emulsion which uses the formed water-proof film to resist fade of makeup caused by tears and perspiration. Typical film formers are not soluble in water. In nail enamels nitrocellulose is dissolved in butyl or ethyl acetate and in split hair coatings, a silicone polymer is dissolved in a volatile oil to give a protective coating to the hair. In addition, silicone resin is also used for its film forming properties in long lasting cosmetics such as sun oils and liquid foundations. 5.4.2.1. Polyvinyl alcohol (PVA) -CH2-CH-f-

I

Completely saponifide

OH n CH2-CH-

I

OH

-CH2-CH—

I 0 I

Partially saponifide

c=o I

CH3

PVA is manufactured by saponification of polyvinyl acetate; the viscosity and film strength vary with the degree of saponification and polymerization.

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Table 5.4. Film forming products and typical raw materials

Water (alcohol)

Typical raw material

Product type

Solubility of Film Formers Packs

Polyvinyl alcohol

Hair spray, Hair setting preparations

Polyvinyl pyrrolidone, methoxyethylene anhydrous malate copolymer. Amphoteric methacrylate ester copolymer

Shampoo, Rinse

Cationic cellulose, piperidinium

Nail enamel

Nitrocellulose

Split hair coatings

Silicone gum

Sun oil, Liquid tion

dimethylmethylene

polyacrylate ester copolymer

Aqueous emul- Eye liner, Mascara sion Non-aqueous

Polychlorinated

founda- Silicone resin

The most commonly-used form is about 90% saponified material due to its good solubility and solution stability. In addition to being used to form films in packs, its colloid maintaining properties are also used to stabilize emulsions. 5.4.2.2. Polyvinyl pyrrolidone /

I

O

-CHCH /

Polyvinyl pyrrolidone is manufactured as a polymer from A^-vinylpyrrolidone using a hydrogen peroxide catalyst. It dissolves easily in water to form a viscous liquid, and it is also soluble in alcohol, glycerin, and ethyl acetate. It is used in hair-care products due to its film forming properties and close affinity for hair, as well as in shampoos to stabilize the lather and give luster to hair. 5.4.2.3. Nitro cellulose Nitro cellulose is an ester of cellulose nitrate; it is soluble in acetates and ketones, etc., and has good phase solubility with other resins. It forms hard films so it is used as a film former for nail enamel. 5.4.2.4. Silicone gum CH3

I

CHa-Si-O

I

CH3

CH3

I

-Si-0

I

CH3

CH3

I

-Si-CH3

I

CH3

n = 5,000—8,000

142 New cosmetic science

Silicone gum is a high-molecular weight straight-chain dimethyl polysiloxane forming a smooth rubbery gum. It is soluble in volatile oils such as isoparaffin and low molecular weight silicone oils and is used in hair care products to coat split hair; after the solvent oil has evaporated a thin film repairs and protects the split hair.

5.5. Ultraviolet absorbents The surface of the earth is continually bombarded with ultraviolet (UV) rays in the wavelengths from 290^00 nm. Ultraviolet absorbents in cosmetics are used to absorb UV light over the entire wavelength band of 290-400 nm to prevent skin damage^^^ including skin erythema, sunburn, suntan, and premature aging^^\ as well as deterioration of the cosmetic itself and the container, such as pigment color changes, breakdown of base materials, quality changes and weakening of the container. The important requirements of UV absorbents used in cosmetics are: (1) non-toxic, with high safety and causing no skin damage; (2) high UV absorbance over a wide range of wavelengths; (3) no breakdown due to UV light and heat; and (4) good compatibility with cosmetic base materials. The main UV absorbents used in cosmetics at present are, based on the chemical structure, benzophenone derivatives, para-amino benzoic acid derivatives, paramethoxycinnamic acid derivatives, salicylic acid derivatives, etc. Table 5.5 lists the main agents with their chemical formulae and maximum wavelength absorbance (>lmax)^^^- Fig5.2 also shows the absorption spectrum of some typical UV absorbents^^^ Although it is possible to assess the effectiveness of UV absorbents by measuring their UV transmission or absorbance at a fixed concentration in an appropriate medium, since the absorption and absorption position changes with the type of solvent, etc., it is very difficult to evaluate the effectiveness accurately. At present, the most commonlyused method for measuring the UV absorption efficiency is to measure the actual human sun protection factor (SPF) (refer to Part II Chapter 5)^3).

5.6. Antioxidants Cosmetics are composed of fats, oils, waxes as well as surfactants and perfumes, etc.; some of these compounds contain unsaturated bonds. In particular, it is presumed that fats and oils with two or more unsaturated bonds are easily oxidized. In cosmetics, this reaction produces compounds with bad smells or causes safety problems such as skin irritation. To prevent these changes in quality, it is necessary to add antioxidants to cosmetics to control this oxidation reaction. Oxidation mechanisms are classified into two types: auto-oxidation, and non-radical oxidation. Auto-oxidation proceeds in the presence of oxygen via a radical-chain mechanism. Non-radical oxidation proceeds in the presence of ozone, single oxygen, etc. 5.6.1, Auto-oxidation

mechanism

Auto-oxidation is a radical chain reaction occurring due to the presence of 20% oxygen

Raw materials of cosmetics

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Table 5.5. Main ultraviolet absorbents

Benzophenon derivatives (1) 2-Hydroxy-4-methoxybenzophenone (2) 2-Hydroxy-4-methoxybezonphenone -5-sulfonic acid (3) Sodium 2-hydroxy-4-methoxybezonphenone-5-sulfonate (4) Dihydroxy-dimethoxybenzophenone (5) Sodium dihydroxy-dimethoxybenzophenone sulfonate (6) 2,4-Dihydroxybenzophenone (7) Tetrahydoxybenzophenone Para-aminobenzoate derivatives (8) Para-aminobenzoic acid(PABA) (9) Para-aminobenzoate (10) Glyceryl para-aminobenzoate (11) Amyl para-dimethylaminobenzoate (12) Octyl para-dimethylaminobenzoate

-OCH3

288,325 285,320

HO SO3H

''^

(Q^co^0^ocu, HO (2)

H^N-^O^-CO^H

288

(8) CH3

/N~KQ>~CO, - CH, - CH - (CHJsCHs CH3

Methoxycinnamic acid derivatives (13) Ethyl para-methoxycinnamate (14) Isopropyl para-methoxycinnamate (15) Octyl para-methoxycinnamate (16) 2-Ethoxyethyl p a r a - m e t h o x y c i n namate (17) Sodium para-methoxycinnamate (18) Potassium para-methoxycinnamate (19) Di-para-methoxycinnamoyl-mono-2 -ethylhexanoyl glycerol

(Imax)

Structure

UV Absorbent (Chemical Name)

^— (12)

1 CH2CH3

310

CH3 0 - x O ) ^ C H = CH-C02-CH3CH(CH2)3CH3 (15)

312

CH2CH3 CH20CO-CH(CH2)3CH3

C H 3 0 - / P ^ C H = CH-C02CH vrrv 1

' ru Url2Url3

CH30-(Q)-CH-CH-C02CH2 (19)

Salicylic acid derivatives (20) Octyl salicylate (21) Phenyl salicylate (22) Homomenthyl salicilate (23) Dipropylene glycol salicylate (24) Ethylene glycol salicylate (25) Myrystil salicylate (26) Methyl salicylate

312

corl'"' © r j d^cH3

308

(22)

CH3

Other (27) Urocanic acid (28) Ethyl urocanate (29) 4-t-Butyl-4'-methoxydibenzoylmethane(Parsol A) (30) 2- (2'-Hydroxy-5-methylphenyl) benzotriazole (31) Methyl anthranylate

1

^ = ^

CH3

II

II

0

^ ^

0 358

(29)

CH3

a:>^

298,340

HO

(30)

(Society of Japan Pharmacopoeia : The Japanese Standards of Cosmetic Ingredients, 2nd Edition, Yakujinipposha, 1984) (Japan Cosmetic Industry Association : Japan Cosmetic Ingredients Dictionary, 2nd Edition, Yakujinipposha, 1989)

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<

320

340 Wavelength (nm)

Fig. 5.2. Absorption spectra of ultraviolet absorbents (Y. Takase, M. Ishihara, K. Toda, F. Morikawa eds: aging and Skin, Seichi Shoin, 1986).

in the air and it is the most important reaction to be noted to prevent the oxidation of cosmetics. Auto-oxidation response is accelerated or inhibited by many factors including heat, light (UV), metal ions (especially, iron and copper), water, proteins, etc. The following equations shows the main reactions of the auto-oxidation mechanism. Initiation of chain reaction Chain transfer reaction Termination of chain reaction

RII ROOH ROOH R • RO. • RO • R • R • RO, •

+ + + +

M'" 0. RH RH

+ R • + RO, • + RO, •

-^ ^ ^ -^ ^ ""> —>

^

R • + • OH RO+ ]Vi('Hi)+^ RO • RO, • ROOH + R • +R • ROH RR ROOR ROOR

OH

( 1) (2) (3) (4) (5) (6) (7) (8) (9)

The auto-oxidation reaction is a chain reaction, so lipid peroxides accumulate rapidly. If lipid peroxide is present initially or accumulates by the progress of auto-oxidation, as shown by equation (5), the radical chain reaction can be initiated again, as shown by equations (2) and (3)3435). 5.6,2, Prevention of oxidation To prevent the auto-oxidation reaction, it is necessary to suppress the initiation and chain transfer reaction phases. Reactions (1) and (2) can be suppressed by storage in a cool

Raw materials of cosmetics

145

location and by use of UV absorbents. In addition, since lipid peroxides are a source of radicals, peroxides should be decomposed by a non-radical mechanism. Chelating agents are useful in suppressing reaction (3); in addition, oxygen accelerates the radical chain reaction so it should be eliminated. In addition to preventing generation of radicals, reactions (4), (5) and (6) should be suppressed by scavenging generated radicals as quickly as possible, thereby breaking the chain reaction. Compounds able to perform these functions are called chain-breaking antioxidants and some are listed below: tocopherols BHT (dibutylhydroxytoluene) BHA (butylhydroxyanisol) gallic acid esters NDGA (nordihydroguaiaretic acid), etc. These antioxidants may be used singly or in mixtures where they often have a synergistic effect. Such materials are often also marketed as mixtures of antioxidants and other compounds promoting the antioxidative effect. Typical antioxidant promoters are phosphoric acid, citric acid, ascorbic acid, maleic acid, malonic acid, succinic acid, fumaric acid, cephalins, metaphosphate, phytic acid, EDTA, etc. When using antioxidants and antioxidant promoters in cosmetics, attention must be paid to irritation, toxicity, and color changes; in addition, they must be dissolved in an oil-water system. It is also necessary to contribute to antioxidation in the system. 5.6.3. Confirmation of efficacy of antioxidants The efficacy of antioxidants is expressed as the ease with which the antioxidant itself is oxidized, or in other words, how easily hydrogen is eliminated, using the redox potential. For the application of antioxidants to cosmetics, some experiments are necessary to determine the kind and amount of antioxidants. There are a number of methods including the AOM (active oxygen method), the Schaal oven test, the oxygen absorption method, the UV irradiation method, and the heating method. All of these are performed under accelerated conditions, so in actual use, it is preferred to perform a comparison using preservation tests to confirm whether or not the results of the accelerated tests are in line with actual results. In addition to selecting the appropriate type and amount of antioxidant to prevent oxidation and maintain the cosmetic quality, it is important to choose high-quality raw materials for cosmetics that do not include impurities which might promote oxidation, as well as to establish appropriate manufacturing methods, and to prevent inclusion of metal ions and other oxidation promoters. Recently, lipid peroxidation has received much attention in connection with its pathological effect and possible contibution to aging, cancer and other diseases^^^ In other words, antioxidants may not just prevent the oxidation of cosmetics, they can play an important role in preventing oxidative reactions in the skin thereby preventing damage caused by UV radiation and aging.

146 New cosmetic science

5.7. Sequestering agents When metallic ions are mixed with cosmetics, they can directly or indirectly lower the quality. Metallic ions can cause changes in perfume and color and can also promote oxidation of oily raw materials. In addition, they can block the action of pharmaceutical agents and can cause transparency to be lost through precipitation, for lotions, etc. Compounds used to deactivate these metallic ions are called sequestering agents. Some typical sequestering agents for metallic ions are listed below but the most generally used is the sodium salt of EDTA: (1) sodium edetate (EDTA) (2) phosphoric acid (3) citric acid (4) ascorbic acid (5) succinic acid (6) gluconic acid (7) sodium polyphosphate (8) sodium metaphosphate

5.8. Other raw materials In addition to the previously described components of cosmetics, there are a number of liquids such as ethanol used in liquid hair setting hair care products and hair tonics, and ethyl acetate used as a solvent for the resins used in nail enamels; there are also propellants used in aerosols as well as metallic soaps used for the purpose of dispersing pigments. This last section only deals with metallic soaps. 5.8.L Metallic soaps Metallic soaps are defined as soaps containing a metal salt of a higher fatty acid; the most common are the alkali metal salts such as sodium and potassium of higher fatty acids. Other non alkali metal salts include calcium, zinc, magnesium, and aluminum, etc.. Metallic soaps are obtained by double decomposition of alkali metal salts of higher fatty acids and metal salts such as zinc sulfate, or by direct mixing of metal oxides and hydroxides with higher fatty acids. They are insoluble or only slightly soluble in water. Metallic soaps have different properties depending on the structure of the fatty acid and type of metal ion but they have various functions, such as improving the dispersability of pigments, as well as improving the viscosity of lipid materials by gelation and increasing the smoothness on the skin and the adhesion. Zinc stearate is used in face powders and baby powders to improve the smoothness and feeling on use. Aluminum stearate is used to increase the viscosity of liquid paraffins, while magnesium stearate is used to improve pigment dispersion^^^

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References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36.

Japan Petrology Association: Lipid Chemistry Handbook, 1, Manizen, 1958. Itoh, S.: Fragrance J., 17 (12), 23 (1989). Ozawa, T., Uehara, K., Nakano, M., Kobayashi, S.: Fine Chem., 14 (18), 67 (1985). Society of Japan Pharmacopoeia: The Japanese Standards of Cosmetic Ingredients, 2nd edn, 862, Yakujinipposha, 1984. Miwa, T. K.: Lipid Chem.., 27 (10), 650 (1978). Society of Japan Pharmacopoeia: The Japanese Standards of Cosmetic Ingredients, 2nd edn, Yakujinipposha, 1984. Petrology Asociation, Glossary of Petrology Terms, 227, Saiwaishobou, 1977. Nikko Chemicals, Japan Surfactant Association: Basic Materials of Cosmetic Formulations, 38, 1977. Goebel, C : J. Am. Oil Chem. Soc, 36, 600 (1959). Japan Petrology Association: Dictionary of Oil Terminology, 63, 600 (1959). Society of Japan Pharmacopoeia: The Japanese Standards of Cosmetic Ingredients, 2nd edn, Yakuji Nippo Ltd., 1984. Todd, C , Byers, T.: Cosmet. Toiletries, 91 (1), 29 (1976). Disapio, A. J., Fridd, P.: Int. J. Cosmet. Sci., 19 (2), 75 (1988). Disapio, A. J.: Drug Cosmet. Ind., 154 (5), 29 (1994). Kawase, J., Tsuji, K.: J. Chromatogr., 267,149 (1983). Ozawa, T.: Fragrance J., 3 (5), 43 (1975). Blank, I. H.: J. Invest. Dermatol., 18, 433 (1952). Gaul, L. F. et al: J. Invest. Dermatol., 19, 9 (1952). Jacobi, O. K.: Proc. Sci. Sec. Toilet Goods Assoc, 31, 22 (1959). Spier, H. W., Pascher, G.: Hautarzt, 7, 2, 1956. Laden, K., Spitzer, R.: J. Soc. Cosmet. Chem., 18, 351, 1967. Imahori, K., Yamakawa, T., Eds.: Dictionary of Biochemistry, 376, Tokyo Science Group, 1984. Akasaka, H., Seto, S., Yanagi, M., Fukushima, S., Mitsui, T.: Jpn. Cosmet. Technologist Publications, 22 (1), 35 (1988). Akasaka, H., Yamaguchi, T.: Fragrance J., 14 (3), 42 (1986). Wenninger, J. A., McEwen Jr, G. N., Eds.: International Cosmetic Handbook, The Cosmetic, Toiletry and Fragrance Association, 1993. Kapadia, Y. M.: Cosmet. Toiletries, 99 (6), 53 (1984). Idson, B. I.: Cosmet. Toiletries, 103 (12), 63 (1988). Lockhead, R. Y., Fron, W. R.: Cosmet. Toiletries, 108 (5), 95 (1988). Horio, T.: Fragrance J., 15 (3), 11 (1987). Tsuji, T.: Fragrance J., 17 (1), 34 (1989). Japan Cosmetic Industry Association: Japan Cosmetic Ingredients Dictionary, 2nd edn., Yakuji Nippon Ltd., 1989. Takase, Y., Ishihara, M., Toda, K., Morikawa, F.: Aging and Skin, Seishi Shoin, 1986. Fukuda, M., Naganuma, M.: Fragrance J., 15 (3), 26 (1987). Helmut, S., Ed.: Oxidative Stress, Academic Press, London, 1985. Mukai, K., Kaifuku, K., Okabe K., Tanigaki, T., Inoue, K.: J. Org. Chem., 56 (13), 4188 (1991). Helmut, S., Ed.: Oxidative Stress, Oxidants and Antioxidants, Academic Press, London, 1991.

6

Cosmetics and pharmaceutical agents

To heighten the basic role of cosmetics in maintaining the homeostasis of the skin, or to achieve a positive pharmacological effect, various pharmaceutical agents are often added to cosmetics. This chapter explains the main pharmaceutical agents used in cosmetics classified by their roles. In addition, Section 6.8 explains the other principle agents used in cosmetics classified by the kind of agents.

6.1. Whitening agents An abnormal increase in the amount of melanin in the epidermis is the main cause of hyperpigmentation such as chloasma, or freckles, etc. Some of the principle causes are exposure to UV light, female hormones, and genetic reasons, but in many cases the details of the mechanism are not clearly understood. Consequently, pharmaceutical agents which control melanin production or melanin metabolism are used as whitening agents. Whitening agents are believed to act on the production and metabolism of melanin in the skin by inhibiting melanin production in melanocytes, reducing extant melanin, promotion of melanin excretion in the epidermis, and selective toxicity to melanocytes. The agents which inhibit melanin production, such as arbutin, kojic acid, vitamin C and its derivatives and placenta extract, are used in whitening cosmetics because of their low toxicity to melanocytes. Whitening cosmetics come onto the market as effective cosmetics in preventing hyperpigmentation such as chloasma and freckles caused by sunlight. Hydroquinone has a strong effect and it is used for OTC drugs in the USA but is not used for cosmetics because of doubts over side effects. 6.1.1.

Arbutin

Arbutin is the common name for hydroxyquinone-)8-D-glucopyranoside (4'-hydroxyphenyl-)S-D-glucopyranoside) and it has the chemical structure shown in I. Its ability to control melanin production has been demonstrated by various in vivo and in vitro tests. In non-cellular in vitro test systems using tyrosinase, a key oxidase in melanin production, arbutin inhibited the activity of mushroom tyrosinase (commercial grade: Sigma) and tyrosinase derived from B16 mouse melanoma. In the case of mushroom tyrosinase, arbutin acts as a competitive inhibitor of tyrosinase^l In studies at cellular levels using cultured B16 melanoma cells, arbutin inhib148

Cosmetics and pharmaceutical 140

140

120

I I Cell increase rate 120 ^ ^ Melanin production rate 100

100 80 ^

60

40 20

n

I

I

lO-'M

80

agents

149

;3 O

I

60

fe i

1 i

'S

40 20

^

lO-'M 5xl0-^M lO-'M Arbutin concentration

SxiO-^'M

Fig. 6.1. Effect of arbutin on cell viability and melanin production. *P < 0.01 compared to control (Students ^test; n = 3-5).

ited melanin production without influencing cellular increase (Fig. 6.1) and also lowered tyrosinase activity. Inhibition of melanin production by arbutin is not based on the melanocyte cell toxicity mechanism shown by hydroquinonemonobenzylether, but is thought to either inhibit the activity or production of tyrosinase^-^>. Also, arbutin shows inhibition of melanin production without being metabolized to hydroquinone.

( I ) Arbutin

The in vivo effect of arbutin on UV-induced pigmentation of human skin has been investigated by double-blind tests and it has been reported that applying milky lotions containing arbutin to the skin has some effect (see Chapter 11). 6.L2. Kojic acid Kojic acid is a y-pyrone compound with the structure shown in II. It is produced mainly by microbial fermentation using aspergillus and penicillium spp. and is important in imparting both color and flavor to miso, soy sauce and Japanese sake. Both in vivo and in vitro experiments have shown that kojic acid inhibits melanin production. HO

0

"O

CH2OH

(II)Kojic acid

150

New cosmetic science

In non-cellular in vitro test systems, kojic acid inhibited the activity of mushroom tyrosinase, goldfish and the black guinea pig tyrosinase. In the case of mushroom tyrosinase, the activity was inhibited by a non-competitive inhibition mechanism. This inhibition has been shown to be due to chelation of Cu, a prosthetic group in tyrosinases^ In studies at the cellular level using B16 melanoma cell cultures, it has been confirmed that addition of kojic acid to the cell culture reduces melanin production and tyrosinase activity^\ In in vivo tests, creams containing kojic acid compounds have been reported as effective in preventing pigmentation changes in human skin due to exposure to UVA and UVB7). 6.1.3. Vitamin C and its derivatives Vitamin C is known by the name, ascorbic acid and it is a typical pharmaceutical agent long used in whitening cosmetics to control production of melanin. Its effect is twofold: it reduces the melanin intermediate compound, dopaquinone, in the tyrosinase reaction which produces melanin from tyrosine, and it also reduces the dark colored oxidized melanin to the lighter colored reduced form. Vitamin C is very safe but very unstable. Therefore various derivative compounds (III) are used because of their better stability. Vitamin C phosphate (magnesium salt) has been developed due to its high stability in aqueous solution. When vitamin C phosphate (magnesium salt) is incubated with skin homogenate, vitamin C is released. Moreover, since vitamin C is detected in guinea pig skin after continuously applying vitamin C phosphate (magnesium salt) but is not detected in the untreated skin, the effect of vitamin C phosphate (magnesium salt) is due to the vitamin C metabolized in the body^\ In in vivo tests on the control of melanin production, when products containing vitamin C phosphate (magnesium salt) are used over the long term on highly-pigmented skin after UV exposure, skin color value recovers much faster than in untreated areas^\ 3/2Mg^^ HO

OH

NaO

HOCH

OSOsNa

0.

HOCH

I

HOCH

I

HOCH2

I

HOCH2

(III-l) Vitamin C

HOCH2

(III-2) Vitamin C-2-sulfate HO

^OPOa"

OH

(III-3) Vitamin C-2-phosphate

HO^

^o>°

/OCO(CH2)i4CH3

o

HOCH

0

HOCH

I

I

CH3 (CH2) 16 CO CH2 CH3 (CH2) H C O CH2 11 II 0 O (III-4) Vitamin C-stearate (III-5) Vitamin C-2,6-dipalmitate (III)

Vitamin C

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151

6.2. Hair growth promoters The causes of male scalp hair loss (alopecia) are: (1) reduced hair follicle function due to effect of male hormones, (2) reduced physiological function of scalp, (3) reduced metabolism function of hair follicle and hair bulb, (4) reduced blood flow due to scalp tension, (5) poor nutrition, (6) stress, (7) side effect of medicines, (8) genetic reasons, etc., (see Chapter 2). However, the reasons for hair loss are not completely understood. Consequently, hair growth promoters include various compounds to alleviate these causes of hair loss. Most products focus on components that stimulate the activity of the hair matrix and blood capillaries. These compounds promote hair growth by supplying nutrients through promotion of blood circulation and activating the hair follicles in the catagen and telogen phases. Hair growth promoters are classified according to their active ingredients and purpose. 6.2.1.

Vasodilators

Vasodilators which improve the flow of blood in the peripheral blood vessels are formulated in hair-care cosmetics. They can be classified into blood-flow stimulants which restore blood circulation and hair-follicle stimulants which improve secondary blood circulation. 6.2.1.1. Blood flow stimulants The principal blood flow stimulants used in hair growth promoters are swertia extract (swertinogen), cepharanthine, vitamin E and its derivatives, y-orizanol, etc. Swertia extract is an extract containing bitter glycosides of Swertia japonica, Makino, a member of the Gentian family; its principal component is swertinogen. It promotes blood flow by dilating the fine capillaries in the skin thereby supplying nutrients and energy to the hair matrix. Cepharanthine is an alkaloid extracted from the root of Stephania cepharanthia, Hayata, a member of the Tudurafuji family. It functions by dilating the blood capillaries. Vitamin E works directly on the skin blood supply and acts by promoting blood flow through vasodilatation of the blood capillaries. 6.2.1.2. Hair follicle stimulants The principle hair follicle stimulants are tinctura capsici, tinctura zingiberis, tinctura cantharidis, nicotinic acid benzyl ester, etc. Tinctura capsici is an ethanol extract of the fruit of the chili pepper. Capsicum annuum, Linneus. The spicy component, capsaicin, promotes hair growth by stimulating the hair root. Tinctura zingiberis is an ethanol extract of the root of Zingiber officinale, Roscoe. The stimulants, zingerone and shogaol both promote hair growth by stimulating the hair root. 6.2.2. Nourishing

agents

Vitamins and amino acids are used to prevent the undernourishment of cells surrounding

152 New cosmetic science

the hair matrix due to insufficient blood circulation around the dermal papilla and hair follicle. 6.2.2.1. Vitamins The principal vitamins are A, Bj, B2, Bg, E, E derivatives, pantothenic acid and its derivatives, and biotin. 6.2.2.2. Amino acids The principal amino acids are cystine, cysteine, methionine, serine, leucine, tryptophan as well as amino acid extracts, etc. 6.2.3. Estrogens (follicle hormone) Since male sex hormones (androgens) are one of the main causes of male scalp hair loss (alopecia), female sex hormones (estrogens) can be used to counter their effect. The main ones are estradiol, ethynyl estradiol, etc. 6.2.4. Hair root activating agents Hair root activating agents improve the function of the hair matrix when reduced by the abnormal activity of various enzymes affecting hair growth. The principal agents are pantothenic acid and its derivatives, placenta extract, allantoin, and quaternium-73. 6.2.5.

Humectants

Humectants prevent the hair from becoming too dry. The principal ingredients are glycerin, pyrrolidone carboxylate. Other hair growth promoters are described in Section 6.5.1. Anti-dandruff and Anti-itching Agents.

6.3. Skin-care agents Skin-care agents achieve an enhancement of the basic functions of cosmetics, add new functions and help maintain healthy skin as well as preventing rough skin. Types of skincare agents include anti-inflammatory agents, astringents, refrigerants, vitamins, hormones and antihistamines. 6.3.1. Antiinflammatory

agents

Anti-inflammatory agents are used to prevent localized inflammation of the skin resulting from external stimuli such as shaving. Typical anti-inflammatories are ^glycyrrhetinic acid, derivatives (IV) of glycyrrhetinic acid, allantoin, azulene, £aminocapronic acid and hydrocortisone (V).

Cosmetics and pharmaceutical

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153

COOH

H HO/I H Y — - f COOH OH H (IV) Di-potassium glycyrrhetinic acid

(V) Hydrocortisone

6.3.2.

Astringents

Astringents are used to refresh and regulate the skin. Typical examples are zinc oxide, zinc sulfate, aluminum hydroxyallantoin, aluminum chloride, zinc paraphenol sulfonate, tannic acid, citric acid, lactic acid, etc. 6.3.3.

Refrigerants

Menthol (VI) and camphor, etc., are used for their cooling effect on the skin. OH ^^C-(

VCH CH3

(VI) Menthol

6.3.4.

Vitamins

At the same time as playing an essential role in maintaining the physiological functions of the entire body, vitamins are important in maintaining the physiological functions of the skin, and they are used to prevent skin diseases caused by vitamin deficiencies. 6.3.4.1. Vitamin A Vitamin A is used in the form of retinol or fatty acid esters such as palmitate and acetate. It is effective in preventing skin abnormalities such as dry skin and keratosis.

154

New cosmetic

science

6.3.4.2. Vitamin B group The B vitamins are used in the form of 65 (pyridoxine hydrochloride) (VII.l) and its fatty-acid esters) and as derivatives of nicotinic acid (VII.2) (nicotinamide, and the benzyl ester). It is useful in preventing seborrhea, and eczema and also activates skin regeneration. CH2OH J^CH.OH

HO

^ ^ C O O H

(VII-1) Pyridoxine

(Vll-2) Nicotonic acid

(Vll-3) Vitamin D2 (Ergocalciferol)

CH3

CH3

1

CH3

I

I

I

CH,lcH,-CH3-CH-CH2 + CH3-CH3-CH-CH,-hCH,-CH3-CH-CH3

(VIl-4) Vitamin E (or-Tocopherol) COOH

I

CH2

I

CH2

I

CH3OH

I ' I

HO-CH2-C-

I

CH3

CH2

O

I

II

CH2

CH-C-N-CH2-CH2-COOH

I

I

H

(VII-5) Pantothenic acid

/

H

CH—C—NH

I

\C. =

/

0

CH2—C NH H (VII 6) Vitamin H (Biotin)

6.3.4.3. Vitamin D Vitamin D prevents eczema and dry skin. Several percent of vitamin D obtained by UV exposure of ergosterol is dissolved in edible oil to be incorporated in cosmetics (VII.3). 6.3.4.4. Vitamin E Vitamin E is used as the fatty-acid ester (acetate). It is know to promote blood flow and inhibit oxidation (VII.4).

Cosmetics and pharmaceutical

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155

6.3.4.5. Pantothenic acid Pantothenic acid (VII.5) prevents skin or lip inflammation. It is used as calcium pantothenate and panthenyl ethyl ether. 6.3.4.6. Vitamin H Vitamin H (VII.6) is called biotin; it prevents skin inflammation. 6.3.5.

Hormones

It is well known that hormones play a major role in maintaining skin homeostasis. 6.3.5.1. Follicle hormone (estrogens) Estradiol (VIII) and its ester, as well as estron, ethynyl estradiol, etc. are used. H3C OH

HO (Vlll) Estradiol

6.3.5.2. Adrenocortical hormone (ACH) Cortisone and its ester, as well as hydrocortisone (V) and its ester, prednisone, prednisolone, etc. are used. 6.3.6.

Antihistamines

Histamines are produced as a result of the slight stimulus when the skin is rough even if it is not caused by pathological conditions such as a rash or allergy; these histamines make the skin itchy and abnormal. Various antihistamines are used to prevent this effect of histamines. Their use is also regulated by legislation. Diphenhydramine hydrochloride (IX), chlorpheniramine malate, glycyrrhizin derivatives, etc., are typical antihistamines.

O^

CHOCHaCHsNCr^u' • HCl

(IX) Diphenhydramine hydrochloride

6.3.7. Others (1) (2)

Shampoos, rinses, and soaps used to keep skin and hair clean contain anti-bacterial agents such as zinc pyrithione, trichlorocarbanilide, triclosan, etc. Some plant extracts showing anti-inflammatory and cell rejuvenation activities such as aloe extract, ginseng extract, licorice extract, rhubarb extract, chamomile extract, loquat oil, etc., are also used.

156 New cosmetic science

6.4. Anti-acne agents Acne has a variety of causes (see Chapter 1) and many different agents are used in combination in cosmetics to counter the various causes (Fig. 6.2). Excess sebum secretion is countered by sebum secretion inhibitors whereas keratin blockage of hair follicles is treated with keratolytic agents and corneocyte desquamating agents; the increase in bacteria is controlled using antibacterial agents. 6.4.1. Sebum secretion

inhibitors

Excess secretion of sebum is due to the action of male hormones. Consequently, it is necessary to control sebum secretion from the skin. Based on this observation, female sex hormone (estrogens), which is antagonistic to male sex hormones (androgens), is used to control sebum. However, since this female sex hormone is a powerful agent, its use in cosmetics is very limited. The amounts and types vary from country to country but their use is not permitted in cosmetics and OTC drugs in the USA. The main forms of female sex hormone (estrogens) used in cosmetics are estradiol, estron, and ethynyl estradiol. In addition, vitamin Bg is also used due to its antiseborrhoeic action. 6.4.2. Corneocyte desquamating

agents

When acne occurs, there is excess keratinization in follicles and comedos result; to open Effect of Hormones, etc. Excess Skin Lipids < ^

Sebum secretion inhibitors

Decomposition by lipase derived from bacteria

t

Bacteria


Free Fatty Acid Formation

Keratosis of Hair Follicle

i

Z\ Anti-Inflammatory Agents

Keratosis in Hair Duct

i

Keratin Dissolution Agents

Formation of Comedo

Corneocyte Desquamating Agents

Fig. 6.2. Causes and treatments of acne.

Cosmetics and pharmaceutical

agents

157

these comedos and remove the contents, various desquamating agents and keratin dissolution agents including sulfur, salicylic acid (X) and resorcinol (XI) are used. Recently, a-hydroxyacid (AHA) is being used in a number of cosmetics due to its expected peel-off and anti-wrinkle properties. COOH .OH

(X) Salicylic acid

"OH (XI) Resorcinol

Sulfur has a long history as a topical treatment for acne, and is used widely at concentrations of 1-10%. The mechanism by which sulfur acts is still largely unknown, but sulfur is involved in the formation of S-S bonds in the reaction with amino acids having SH groups, such as cysteine and glutathione, found in living tissues; sulfur itself changes to sulfur hydride (H2S) which shows keratin dissolution and corneocyte desquamating properties. Salicylic acid is effective against comparatively-slight acne and it has been used for over 100 years at concentrations of 0.5-3% to treat inflammation caused by acne. At higher concentrations, it is said to be effective in preventing formation of comedos. Resorcinol is normally used in combination with sulfur and it has both corneocyte desquamating and antibacterial properties. 6.4.3. Antibacterial

agents

Propionibacterium acnes are an important causal factor in acne and a reduction in the bacterial population is believed to be linked to recovery from acne. The principal agents are benzalkonium chloride, benzethonium chloride, halocarban, 2,4,4-Trichloro-2-hydroxyphenol, etc. 6.4.4. Others When it is necessary to reduce inflammation, anti-inflammatory drugs such as glycyrrhizic acid and glycyrrhetic acid are used. In addition, vitamin A and its derivatives (IS-c/i'-retinoic acid, etc.) as well as benzoylperoxide, etc., are very effective in treating acnei^\ However, such use is not permitted in Japan. Recently, IS-c/^-retinoic acid is attracting attention as an anti-wrinkle agent.

6.5. Anti-dandruff and anti-itching agents Dandruff can be classified into both dry and oily dandruff; in dry dandruff, there is excess keratinization and the abnormal peel off of the keratin layer. In oily dandruff, there is abnormal production of skin lipids. In severe dandruff, there is decomposition of the lipids by scalp bacteria; the decomposition products irritate the scalp causing itching and inflammation accompanied by pityriasis and chronic pityriasis type hair loss.

158 New cosmetic science

The causes of dandruff are (1) abnormal keratinization of the epidermal tissues, (2) excessive lipid secretion due to abnormal internal secretion, and (3) abnormal proliferation of scalp bacteria. As a consequence, medicated shampoos, rinses and hair growth promoters for preventing dandruff contain comeocyte desquamation agents, keratin dissolution agents, antiseborrhoea agents and antibacterial agents. In addition, to prevent worsening of itching and inflammation, they contain anti-inflammatories and anti-itching agents. 6.5.1. Comeocyte desquamating

agents

These agents are used to treat dry dandruff; the main drugs are salicylic acid, sulfur, resorcinol, and selenium sulfide. 6.5.2. Antiseborrheic

agents

The principal antiseborrheic agent is vitamin B^ and its derivatives. 6.5.3. Antibacterial

agents

Although there is not always a definite correlation between dandruff and microorganisms, antibacterial agents are used to maintain a clean scalp and inhibit microbial growth. It is said that antibacterial agents control itching and smell by inhibiting the production of free fatty acids generated by the action of lipase derived from microorganisms. The principal anti-bacterial agents are trichlorocarbanilide + tocopherol acetate, zinc pyrithione, benzalkonium chloride, benzethonium chloride, chlorhexidine, hinokitiol, phenol, isopropylmethylphenol, etc. Of these, the combination of trichlorocarbanilide and tocopherol acetate provides both antibacterial and antioxidation effects, and double-blind tests have proved its synergistic effect in inhibiting the production of dandruff. 6.5.4. Antiinflammatory

agents

The principal anti-inflammatory agents are glycyrrhenitic acid and its derivatives, hydrocortisone acetate, and prednisolone, etc. 6.5.5. Antipruritic

agents

The principal antipruritic agents are diphenhydramine hydrochloride, chlorpheniramine malate, camphor, menthol, etc.

6.6. Antiperspirants and deodorants The major components of body odor are products decomposed from a mixture of sweat and lipid broken down by the normal bacterial flora of the skin; these breakdown prod-

Cosmetics and pharmaceutical agents

159

ucts cause body odor. One group of unpleasant smelling breakdown products is reported to be the lower fatty acids^^^. Cosmetics for preventing body odor contain antiperspirant and antibacterial agents for reducing the number of normal skin bacteria as effective agents. 6.6.1.

Antiperspirants

Antiperspirants suppress production of perspiration due to their strong astringent action on the skin. Typical antiperspirants are aluminum hydrochloride, aluminum chloride, aluminum chlorhydroxyallantoinate, potassium aluminumsulfate, zinc oxide, zinc paraphenol sulfonate, etc. Of these, aluminum hydrochloride is used most often. The larger the contact area of skin with powders, the more effective the antiperspirant becomes. Consequently, ultrafine powders have been made to enlarge the surface area of the powder. However, zirconium compounds are also excellent antiperspirants, and they have been approved in the USA for use except in powder-type antiperspirants; they have not been approved in Japan. A number of methods are used to evaluate antiperspirants, but the most common involves measuring the amount of perspiration of the human armpit (FDA method)^^\ In this method, one armpit is coated with antiperspirant and the other uncoated armpit is used as the control. Weighed cotton pads are fixed to each armpit and the volunteer remains in a high-temperature-controlled room for a fixed period where the cottons pads absorb the produced perspiration. The pads are weighed at the end of the test to measure the amount of perspiration produced and the effectiveness of the antiperspirant can be evaluated from the ratio of the weights. However, before using this method, it is necessary to measure the normal sweat production of each armpit of the volunteer. 6.6.2. Antibacterial

agents

The principal antibacterial agents are benzalkonium chloride, benzethonium chloride, halocarban, chlorhexidine chloride, etc. 6.6.3.

Deodorants

Recently, it has been reported that one component of body odor are the lower fatty acids^ ^\ Zinc oxide is used widely as an effective agent for eliminating body odor. The mechanism by which zinc oxide eliminates body odor is described below. Lower fatty acids have strong smells because they volatilize easily. The volatilization decreases by changing them to metallic salts from free fatty acids by using zinc oxide and so the smell decreases. In other words, the bad odor of these compounds can be removed by the formation of metallic salts through combination with metal ions such as zinc (refer to Part I, Chapter 11).

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6.7. Oral care agents Oral care agents are used in oral care products to enhance their basic functions or to add new functions. 6.7.1. Anticariogenie

agents

Keyes^^) clarified that carious teeth are caused by three main factors: (1) consumption of sweet foods, (2) cariogenic bacteria, and (3) susceptibility of teeth. Anti-cariogenic agents prevent caries by attacking points (2) and (3). The bacteria causing carious teeth are found in the dental plaque coating the teeth; the main cariogenic bacteria, Streptococcus mutans, uses glucosyltransferase to produce insoluble glucan from sucrose; glucan adheres to the teeth and is converted to lactic acid as a result of the bacterial energy metabolism. It is this lactic acid which attacks the tooth enamel and results in caries. To prevent caries, it is necessary to (1) strengthen the acid resistance of teeth, (2) kill the cariogenic bacteria, and (3) decompose the glucan formed by bacteria and inhibit its production. In other words, oral care agents use three types of agents to deal with these problems. 6.7.1.1. Strengthening acid resistance of teeth Many compounds have long been used to strengthen the acid resistance of teeth; they include sodium fluoride (NaF), sodium monofluoroide phosphate (Na2P03F) and stannic fluoride (SnF2). The mechanism by which these fluoride compounds strengthen the resistance is based on combination of the fluoride ions with part of the hydroxyapatite structure forming the main constituent of tooth enamel and this fluoroapatite is believed to have increased acid resistance. 6.7.1.2. Antibacterial agents The most commonly-used antibacterial agent is chlorhexidine gluconate (XII), a broadspectrum bactericide. Other similar agents are cetylpyrridinium chloride (XIII) and isopropylmethylphenol, etc.

•2C6H,207

NH-C-NH-C-NH-(CH2)6-NH-C-NH-C-NH i II II II NH NH NH NH (Xn) Chlorhexidine Digluconate

C l ^ ^(CH2)l4CH3

^N H2O

(Xni) Cetylpyrridinium chloride

Cosmetics and pharmaceutical agents 161 6.7.1.3. Agents of glucan decomposition and inhibitors of glucan formation The insoluble compound, glucan, produced by cariogenic bacteria has a a-1,6 or a-1,3 polymer bond structure. Both a-l,6 and a-1,3 bonds can be broken down by oxidizers like dextranase in the case of the former, and mutanase in the case of the latter. Dextranase is already widely used in toothpastes in Japan. 6.7.2. Antiperiodontic

agents

Inflammation of the gums surrounding the teeth is called periodontitis and includes both simple inflammation of the gum tissues or gingivitis as well as alveolar pyorrhea The difference between the two conditions is that in gingivitis, the inflammation is limited to gingiva, whereas in pyorrhea, the alveolar bone supporting the tooth is involved. In pyorrhea accompanying gingivitis, looseness of the teeth is often observed. Pyorrhea alveolaris often develops from gingivitis. In other words prevention of gingivitis prevents the occurrence of pyorrhea. The principal cause of gingivitis is dental plaque, so many oral care products contain compounds intended to suppress plaque (plaque control) and prevent periodontitis. So, they contain antibacterial agents to control plaque, antiinflammatory agents, astringents, and blood circulation promoters. 6.7.2.7. Antibacterial agents Refer to Section 6.7.1. 6.7.2.2. Anti-inflammatory agents (1) Hinokitiol(4-isopropyl tropolone). Hinokitiol (XIV) is obtained from the oil of the Taiwanese cedar tree. It has anti-inflammatory effect, hemostatic effect and bactericidic effect.

CH (m)

(2) (3) (4)

(5)

Hinokitiol

AUantoin. Allantoin and its derivatives are used as anti-inflammatories, astringents and cell rejuvenants. Glycyrrhizinic acid and its salts (IV). Glycyrrhizinic acid and its salts are used as anti-inflammatories, astringents and bacterial-growth inhibitors. Antiplasmin agents. In gingivitis, topical fibrinolytic activity increases and it becomes hemorrhagenicin gingiva. Antiplasmin agents such as £-aminocaproic acid and tranexamic acid are used to prevent bleeding and inflammation by controlling fibrinolysis in Japan. Others. Other compounds used as antiperiodontic agents include dihydrocholesterol, azulene, extracts of JapanesernigolicdLAngelicae radix, root, etc.

162 New cosmetic science

6.7.2.3. Astringents Astringents are used to constringe the gingiva; typical ones include aluminum allantoin and aluminum lactate. 6.7.2.4. Blood circulation promoters Blood circulation promoters are used to prevent gum hemostasis and improve blood flow. Vitamin E and its derivatives are typical agents. 6.7.2.5. Others Sodium chloride has long been used to prevent periodontitis and as a gum astringent. In addition, the vitamin, pyrridoxine chloride is also used. 6.7.3. Oral deodorants Bad breath can be caused by respiratory or digestive illnesses as well as by generalized illness and oral complaints. Obviously, the latter problem is the target of oral care products. It is well known that the metabolism and breakdown of proteins and amino acids by oral bacteria can produce foul-smelling hydrogen-sulfide and sulfur compounds like methyl mercaptan, organic acids and nitrogen compounds, etc. Oral deodorants usually contain anti-bacterial agents to suppress the bacteria causing bad breath (refer to Section 6.7.1 for more details). Sodium cupric chlorophene has long been used as an effective oral deodorant. 6.7.4. Antitarta

agents

Dental tarta is believed to be formed by the interaction of organic compounds like plaque on the teeth with calcium in the oral fluids. Antitarta agents typically include sodium polyphosphate and zeolite. 6.7.5. Tar cleansing agents The basic action of tar cleansing agents is to keep the teeth clean using abrasives; agents to enhance this effect include polyethylene glycol, etc.

6.8. Others 6.8.1.

Vitamins

In the same way that vitamins are essential in keeping the whole body healthy, they are also essential in maintaining the normal biophysiological functions of the skin. Table 6.1 shows the roles that different vitamins play in preventing skin diseases. Retinoic acid, a derivative of vitamin A, has long been known to influence the in vivo proliferation and differentiation of the epidermis as well as the synthesis of dermal collagen and elastin^^'^^^. Moreover, vitamin A also promotes the synthesis of hyaluronic acid in epi-

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Table 6.1. The effect of vitamins in cosmetics on skin condition Vitamin

Skin Complaint

Ingredient

Vitamin A

Dry skin, Abnormal keratosis

Fatty-acid esters of vitamin A(palmitate, acetate)

Vitamin B

Seborrhea, eczema

Pyridoxine chloride (B 6), fatty-acid esters of B 6, nicotinamide, y-oryzanol

Vitamin C

Melanosis (liver spots, freckles)

Monostearyl ascorbate, ascorbic acid phosphates, magnesium salts

Vitamin D

Eczema, dry skin, abnormal nails and hair

Vitamin E

Aged skin, acne, ischemic skin

Pantothenic acid

Graying hair, dermatitis, lip inflam- Calcium pantothenate, panthenyl ethyl ether mation

Vitamin H

Dermatitis

E acetate ester (used as cosmetic stabilizer as well)

Biotin

dermal cells in vitro^^^. Recently, vitamin A is also studied as an anti-wrinkle agent. Future research is expected to lead to exciting developments. 6.8.2.

Hormones

The hormones used in cosmetics are limited to follicle hormone (estrogens) and adrenocortical hormone (ACH). The types and amounts are strictly controlled by law which differs between countries. 6.8.3. Amino acids Amino acids are effective in helping recovery of dry and hard skin by moisturizing the epidermis. Typical amino acids are essential amino acids and basic amino acids and their salts. Table 6.2. Plant extracts and active ingredients used in cosmetics ^^^ Antiseborrhea

Witch hazel, Lamium album (L), White birch, Rhubarb etc. (Plants containing tannin)

Anti inflammatories

Licorice, Coptis root, Lithospermi radix, Achillea herba, Symphytum officinale (L), and Aloes, etc.

Anti-bacterial agents

Chamomile (contains azulene), essential oils such as Eucalyptus oil, Hinokitiol etc.

UV blockers

Aloe, Marronnier, /^-carotene, etc. (Plants containing flavonoids)

Skin rejuvenants (promote metabolism, blood circulation, wound healing)

Ginseng extract. Aloe, Lithospermi radix, lilies, loofah, Marronnier, Phellodendri cortex, Safflower

164 New cosmetic science

6.8.4, Extracts from natural resources Both extracts from natural resources as well as constituents obtained from such extracts are used in cosmetics. In particular, a wide variety of plant extracts have long been used due to their well known efficacy and safety, etc. Many of their constituents are used as pharmaceutical agents in cosmetics. Table 6.2 gives some examples of uses and effects of plant extracts and their active ingredients.

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

Fujita, K. etal:. Fragrance J., 18 (6), 72 (1990). Akiu, S. et al.: Jpn. Dermatol. Assoc, 101, 609 (1991). Akiu, S. et al.: Proc. Jpn. Soc. Invest. Dermatol., 12: 138 (1988). Maeda K. et al.: J. Soc. Cosmet. Chem., 42, 361 (1991). Riga Y: Fragrance J., 11 (6), 40 (1983). Hatae, S. et al.: Proceedings of the 11th Technical Congress of the Japan Fragrance Association, 1986. Higa, Y. et al.: Proceedings of the 10th Technical Congress of the Japan Fragrance Association, 1986. Imai, Y. et al.: Jpn. J. Pharmacol., 17, 317 (1967). Takeuchi, M. et al.: Proceeding of the 19th Congress of the Japan Vitamin Association, 1967. Asada, Y.: Acne, Kanehara Shuppan, 1983. Kanda, F. et al.: Cosmet. Toiletries, 108 (Nov), 67 (1993). Antiperspirant drug products for over-the-counter human use., Federal Register, 43, 46694, 1978. Keyes, P. H.: Bacteriol. Int. Dent. J., 12, 443 (1962). Kligman, L. et al.: Connect. Tissue Res., 12, 139 (1984). Tammi, R. et al.: J. Invest. Dermatol., 92, 326 (1989). Komazaki, H. et al.: Fragrance J., Special Issue No. 6, 11 (1986).

7

Cosmetics and physical chemistry

This chapter describes the physical chemistry of cosmetics; physical chemistry is the study of the properties of materials and the changes in those properties. Cosmetics are a mixture of many materials and an understanding of physical chemistry is essential in designing, manufacturing and ensuring the stability of cosmetics. Physical chemistry can be split into many fields but this section focuses principally on colloids, interface science and rheology.

7.1. Colloid and interface science of cosmetics As described in other chapters of this book, cosmetics have a large number of ingredients and forms. To study the various forms in cosmetics, a knowledge of physical chemistry is required. If we speak of cosmetics as one thing, it is a mixture of ingredients in both the soluble and insoluble states. Colloid and interface science is the study of the properties and changes of these types of states, and as a consequence, it is not an exaggeration to say that the physical chemistry of cosmetics really means the colloid and interface science of cosmetics. After giving a simple definition of colloids and classifying them, as well as defining interface science, this chapter describes a number of items closely related to cosmetics. 7.1.1. Colloids and interfaces 7.1.1.1. Colloids The states of cosmetics described above is defined in physical chemistry terminology as a dispersion system or simply as the dispersion. Colloids are also a dispersion system although it is extremely difficult to define colloids precisely. A dispersion system is a system in which particles are dispersed randomly in a uniform continuous medium. The medium is called the dispersion medium and the dispersed particles are called the disperse phase. The dispersion medium can be any of the gaseous, liquid or solid phases, but the disperse phase can include lone-molecules and ions, in addition to these three phases. The dispersion system can be classified into three types: molecular, colloidal, and coarse dispersion, depending on the size of the dispersed particles. In the molecular dispersion system, the disperse phase is formed of lone molecules or ions up to about 1 nm in size; this could also be described as a solution or a solid solution. The size of the dispersed particles exceeds about 1000 nm (1 //m) in a coarse dispersion, which is not macroscopically homogeneous and separates over time. In a colloi165

166 New cosmetic science

dal dispersion, the size of the dispersed particles is between molecular and coarse dispersions and can be from 1 to 1000 nm. However, the size range of the particles is not strict. Colloidal dispersions can range between clearly stable states (molecular dispersion) and unstable states (coarse dispersion). As a consequence, colloidal dispersions are divided into the following three types based on the properties of the dispersed particles. (1) Molecular colloids. In a molecular colloid, macromolecules are dissolved in a solvent forming a macromolecular solution. The system is a true solution and is thermodynamically stable. At present, macromolecular solutions are not described as molecular colloids. Macromolecular compounds are the subject of polymer science. (2) Association colloids. These colloids are formed from an association of relatively small molecules and ions in solution. Such associations are called micelles (refer to section on micelles) and exist in thermodynamic equilibrium. Association colloids are also truly stable systems. (3) Disperse colloids. The two systems described above exist in thermodynamic equilibrium and are truly stable and single-phase systems. In particular, they are generated spontaneously by mixing. By contrast, disperse colloids are thermodynamically-unstable, multiphase systems in which the dispersion medium and disperse phase have clearly different phases, even if the disperse colloid looks homogeneous macroscopically. Generally, disperse colloids are not formed spontaneously by mixing. However, although there is a difference of degree of the stability between disperse colloids depending on the fineness of the dispersed particles and the surface charge, etc., they can be stabilized (refer to Section 7.14). In addition, disperse colloids can be classified as shown in Table 7.1 based on the relationship between the dispersion medium and disperse phase. At present, the main focus of colloid science is association colloids and disperse colloids, but many of the subjects are the same as in cosmetic science. For example, lotions are association colloids, milky lotions are emulsions and nail enamels are suspensions. However, many cosmetics are not simple colloid systems; many products such as emulsified foundations, creams and hair foams, are very complex systems (refer to related sections). In cosmetics, the main theme for association colloids is how the required colloids can be formed. In the field of disperse colloids, one objective is how to manufacture Table 7.1. ClassiHcation of disperse colloids Dispersion Medium

Dispersion Phase

Name

Example

Gas

Gas Liquid Solid

Aerosol Aerosol

Sprays, Fog Powder sprays, Smoke

Liquid

Gas Liquid Solid

Foam Emulsion Suspension

Shaving foam Milky lotions. Milk Nail enamel

Solid

Gas Liquid Solid

Xerogel Gel Solid colloid

Sponge Pomades, Gelatin jelly Colored glass

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167

such colloids and another is how to improve the stability of these inherently unstable systems. 7.1.1.2. Interface An interface is the boundary between two phases; in the case of the interface between gas and liquid phases, or between gas and solid phases, it is customarily called the surface. In disperse colloids (including coarse dispersions), the interface is extremely large due to the fineness of the particles and is especially important in the physical chemistry. The molecules at the interface are in contact with different molecules on the inside and outside and are different from the state of the molecules at the inner part. Consequently, there is excess free energy at the interface compared to the inner part. The excess free energy per unit area is the interfacial tension. In disperse colloids, there is an interface between the dispersion medium and the disperse particles, and this is much larger than the interface in the fully separated state. As a result, disperse colloids have an extremely large excess of free energy making them thermodynamically unstable. A phenomenon called adsorption also occurs at the interface; for example, adsorption of surfactants at the interface is an essential element of phenomena such as emulsification, wetting and foaming, and is very important in cosmetics. 7.7.2. Properties of surfactants This section explains surfactants, raw materials of cosmetics closely related to the colloid and interface science. Materials that are adsorped at an interface and which greatly reduce the interfacial tension are called surfactants or surface-active agents. They are also called emulsifiers, solubilizers, wetting agents and detergents according to the application. Although there are many types of surfactants, they can have common chemical structures in two groups: a hydrophilic group with an affinity for water, and a hydrophobic group with an aversion for water. This latter group is also called lipophilic due to its affinity for oils. The hydrophobic group usually has hydrocarbon groups forming the main body but there are also fluorocarbon groups and silicone groups. The hydrophilic group can be divided into ionic and non-ionic forms which can be further sub-divided. (Refer to Part I Chapter 5 Section 2.) 7.1.2.1. HLB Surfactants have hydrophilic and lipophilic groups and the factor determining whether a surfactant is hydrophilic or lipophilic is determined by the relative strength of their properties. This concept has long been understood^^ and it is called the hydrophilelipophile balance (HLB). Griffin et al.^^ performed expansion emulsification tests to investigate the HLB of each type of surfactant and gave each surfactant an HLB number (or HLB value). A method^) has also been proposed for calculating the HLB number from the chemical composition of the surfactant. Subsequently, J.T. Davies^^^ classified surfactant molecules into simple chemical groups and determined the intrinsic value (group value) for each shown in Table 7.2. He also proposed a method for determining the total HLB from these values using Eq. (1).

168 New cosmetic science Table 7.2. Group values^) Group

Group Value

Hydrophilic groups -SOsNa -COOK -COONa N (quaternary amine) Esters (sorbitan ring) Esters (isolated) -COOH - O H (isolated) - 0 — OH (sorbitan ring)

38.7 21.1 19.1 9.4 6.8 2.4 2.1 1.9 1.3 0.5

Group Lipophilic groups -CH-CH2- 1 -CH3 = CH- ^ Introduced groups -(CH2-CH2-O)-(CH2-CH2-CH2-O)-

Group Value

-0.475

+ 0.33 -0.15

(J.T. Davies : Proc. 2 nd Intern. Congr. Surface Activity, 1 : 426, 1957.)

HLB number = Z(group value of hydrophilic groups) + E(group value of lipophiUc groups) + 7

(1)

In addition, Kawakami^^ has proposed Eq. (2) as a method for determining the HLB number of non-ionic surfactants from the molecular composition. Mw HLB Number = 7 + 11.71ogMo

(2)

where M^ is molecular weight of the hydrophilic groups and M^ is the molecular weight of the lipophilic groups. Moreover, since the HLB number is additive, it is easy to calculate the HLB number of a mixture of surfactants. In emulsification of various oils, the appropriate surfactant for each oil has an HLB number which is also called the required HLB. Table 7.3 shows the required HLB for each type of oil. The required HLB for a mixture of oils can be calculated since it is also additive. For example, the required HLB for an O/W emulsion of 10% beeswax (HLB 15), 53% liquid paraffin (light) and 37% petrolatum is found as follows: 15x10 + 10x53x10.5x37 = 10.68 10 + 53 + 37

This shows that an emulsifier with an HLB number of 10-11 is required to emulsify this oil component. The HLB number is an effective and easy indicator of the properties of a surfactant. Table 7.4 shows the relationship between the HLB number and the surfactant usage. However, the HLB number and required HLB have been determined empirically without sufficient scientific basis and it is best to consider them as only guidelines to the effectiveness of surfactants.

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Table 7.3. Required HLB^) Raw Materials Hydrocarbons Liquid paraffin (light) Liquid paraffin (heavy) Vasehne (white) Microcrystalhne wax Paraffin (domestic) Plant and Animal Oils, Waxes Cotton seed oil Candelilla wax Carnauba wax Beeswax Lanolin (anhydrous) Fatty Acids and Alcohols, Others Stearic acid Cetyl alcohol Silicone oil(G.E.)

W / 0 Emulsion

0 / W Emulsion

4 4 4 4

10 10.5 10.5 9.5* 9

5 8

7.5 14.5* 14.5* 10—16 15

-?

9

7

17 13 10.5*

* Provisional value (W.C. Griffin : J. Soc. Cosmetic Chemists, 1 : 31L 1949.)

Although the HLB (hydrophile-lipophile balance) and HLB number are often used synonymously, they really should be considered separately. The HLB is a concept that essentially explains the properties of surfactants and the HLB number is one index of the HLB. To estimate the HLB of surfactants more theoretically than using the HLB number, Shinoda^) proposed HLB temperature. The HLB of nonionic surfactants changes with temperature (refer to Section 7.1.2.4). The HLB temperature is the temperature at which hydrophilicity and lipophilicity of surfactants are just balanced in oil-water surfactant systems. At temperatures below the HLB temperature, an 0/W emulsion is formed and at temperatures above it, a W/O emulsion is formed (refer to Section 7.1.4). HLB only expresses the relative strengths of the hydrophilic and lipophilic properties but each absolute strength has a large effect on the properties of the surfactant. The importance of the absolute strength will be understood from the properties and functions of surfactants described below.

Table 7.4. Surfactant HLB number and application HLB Range

Main Application

1.5—3 4—6 7-9 8—18 13-15 15-18

Anti-foaming agents W/O Emulsifiers Wetting Agents 0 / W Emulsifiers Detergents Solubilizers

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QQ999PP

%

^

Ui

o^-^^

ddoOoodo b. a. Spherical micelle (Hartley) c. Rod micelle (Debye)

b. Layered micelle (McBain) d. Small micelle (McBain)

Fig. 7.1. Various micelle forms.

7.7.2.2. Micelle formation and critical micelle concentration A dilute aqueous solution of a surfactant shows the same properties as a normal solution, but if the concentration is slowly increased, the surfactant molecules or ions form aggregations called micelles to produce the association colloids described earlier. Micelles form aggregations of hydrophobic groups on the inner surface, thereby decreasing the number of hydrophobic groups in contact with the water (hydrophobic interaction). The form of the micelle and the aggregation number are determined by the relative strength of the hydrophilic and hydrophobic groups (HLB) and by their respective absolute strengths. Fig. 7.1 shows the inferred form^^ of various micelles. The concentration of the surfactant at which micelles are formed is called the critical micelle concentration or cmc. Since the cmc is the boundary at which the surfactant solubility condition changes from a true solution to an association colloid, it is the point at which the physico-chemical properties of the solution, such as the surface tension and Detergent power

Conductance

Surface Osmotic pressure

Oj"

0:4'

0.6

Consentration of Surface active agent (%) Fig. 7.2. Changes in physical properties with concentration^^. (H. Preston : J. Phys., Coll. Chem., 52 ; 85,1948.)

Cosmetics and physical chemistry 111

coUigative properties (properties related to number of solute molecules, such as osmotic pressure and depression of freezing point) change greatly. Fig. 7.2^) shows the results of an investigation of the various physico-chemical properties of an aqueous solution of an ionic surfactant at different concentrations^^ The figure does not show the turbidity (light scattering) and solubilization, etc. The cmc can be determined by changing the concentration of the surfactant and measuring these properties to find the concentration at which the properties suddenly change. The cmc is determined by the absolute strength of the hydrophobic and hydrophilic groups in surfactants. So far, we have discussed aqueous solutions of surfactants, but surfactants also form similar micelles in oil solutions. In this case, the structure of the micelle is reversed with the hydrophilic groups on the inside (reverse micelle). There are many examples where surfactant functions are exhibited at concentrations above the cmc and many surfactants are actually used in cosmetics at concentrations above the cmc. 7.7.2.3. Liquid crystals The intermediate state between crystal and liquid, in other words, the state in which the molecules are neither arranged as found in a crystal nor as in a liquid, is called the liquid crystal or mesophase. Generally, liquid crystals are easily identified by their intermediate fluidity between solids and liquids and their optical anisotropy. However, there are also optically isotropic liquid crystals. Liquid crystals can be broadly classified into thermotropic liquid crystals and liotropic liquid crystals. In the former, the crystal lattice is partly destroyed by heat, while in the latter, the lattice is partly destroyed by the medium. Liotropic liquid crystals are very closely related to surfactants; generally, they can be formed by mixing surfactants and water at high concentrations. Fig. 7.3 shows the structure of typical liquid crystals. Liquid crystals also consist of surfactant aggregations like micelles, but it is believed that in liquid crystals, the aggregation grows limitlessly in form. Rod-like aggregations with the hydrophilic groups on the outside are filled hexagonally and form a hexagonal phase, or middle phase and when the surfactant layout is reversed, the phase is called the reverse hexagonal phase; lamellar aggregates are filled in layers and form the lamellar phase, or neat phase. The liquid crystal structure is

iauuiaiaauiu

^^^^^^^^^^^^^^^^^^^^

iaauiaaiaauii uuuiaauaiuaj OOOQQQQQQQQQQQOQQQQQl

Hexagonal Phase

Lamellar Phase

Reverse Hexagonal Phase

Fig. 7.3. Illustration of the structure of typical liquid crystals.

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New cosmetic science

u

0.2

0.4 0.6 »0.^ C12E6 Weight Fraction

1.0

Fig. 7.4. Equilibrium phase diagram of Ci2H25(OC2H4)60H and water. IL, one liquid phase; 2L, two liquid phase; M, liquid crystal phase (hexagonal); N, liquid crystal phase (lamellar); S, crystal phase

determined by the surfactant HLB and the concentration. The above structures also reflect the surfactant HLB. Hydrophilic surfactants tend to form hexagonal phase liquid crystals, hydrophobic surfactants tend to form reverse-hexagonal liquid crystals, and intermediate surfactants with a balanced hydrophile-lipophile property form lamellar phase liquid crystals. Fig. 7.4 shows the equilibrium phase diagram of hexaethylene glycol monododecyl ether and water. In the diagram, the IL and 2L regions represent one liquid phase and two liquid phases, respectively; M is the hexagonal phase and N is the lamellar phase. A hydrophilic liquid crystal structure can be formed at the waterdominant side with a surfactant of the same HLB. Liquid crystals can also be formed as mixed surfactant, water and oil systems. In liquid crystals water can be solubilized in the side of the hydrophilic group and oil can be solubilized in the side of the lipophilic groups of surfactants. These types of systems are used as base formulae in the cosmetic field. 7,12.4. Cloud point {lower critical solution temperature) When an aqueous solution of a non-ionic surfactant is heated slowly, it suddenly becomes cloudy. This temperature is called the cloud point. It is also called the lower critical solution temperature. In a non-ionic surfactant with polyethylene glycol hydrophilic groups, since the hydrogen bonds between the water and the ether oxygen of the polyethylene glycol are disrupted with increasing temperatures, the surfactant solubility in water falls with increasing temperatures and the aggregation number of micelle of surfactant increases infinitely and the water phase comes out of solution (cloud point). As a consequence, at the cloud point, the solution separates into the concentrated surfactant phase and dilute phase (usually water). As an example, the cloud point in the equilibrium phase diagram (Fig. 7.4) of the previously-described hexaethylene glycol monododecyl ether and water system follows the curve ABC. Since the concentration of C12E6 on the section AB is too small, the AB line is not drawn accurately on the diagram.

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173

Table 7.5. Krafft point of ionic surfactants Compound

Krafft

PointC

Ci2H22S04Na

16

Ci4H29S04Na

30

C,eH33S04Na

45

Ci8H37S04Na

56

2MeCnH23S04Na

<0

2 MeCi3H27S04Na

11

2 MeCi5H3iS04Na

25

C16H33SO4SH2 (C2H4OH) 2

<0

CieH33(OCH2CH2)3S04Na

19

Ci8H37(OCH2CH2)3S04Na

32

The cloud point is an accurate index of the HLB and it is used as a quality control indicator for non-ionic surfactants. 7.7.2.5. Krafft point The solubility of ionic surfactants in water suddenly increases at temperatures above a certain point. This temperature is called the Krafft point. In simple terms, the Krafft point is the melting point in water of hydrated crystals of the surfactant. Hydrated crystals of the surfactant first melt at this temperature, then form micelles, and dissolve suddenly in water. Accordingly, the Krafft point is lower in surfactants with a chemical structure in which the melting point of the hydrated crystals is lower. Table 7.5 lists the Krafft points of various ionic surfactants. Generally, surfactants function above the Krafft point, so the Krafft point must be taken into consideration when they are used in cosmetics. 7.1.3. Solubilization and

microemulsions

7.1.3.1. Solubilization Aqueous solutions of surfactants are able to completely and transparently dissolve substances that are difficult to dissolve in water. This phenomenon is called solubilization. Solubilization cannot occur at surfactant concentrations below the cmc. Materials such as oils that are insoluble in water are dissolved by incorporation into micelles. Although solubilization systems are transparent, they exhibit the Tyndall phenomenon and can be easily recognized as different from true solutions. The solubilization system is a micellar solution, that is, an association colloid, so it is thermodynamically-stable. The amount of oil that can be dissolved in a solubilization system obviously depends on the amount of surfactant but it can vary extremely with the same amount of surfactant depending on the HLB. Fig. 7.59) shows the temperature dependence of the amount of hexadecan solubilized by aqueous solutions of a non-ionic surfactant. The solubilization region is the range bounded by the cloud point curve and the solubilization boundary. The HLB of the non-ionic surfactant becomes lipophilic with increasing temperature (refer to Section 7.1.2.4). The amount of solubilized oil changes greatly in accordance with this change in HLB, and the maximum solubilization is produced at the most suitable HLB of the surfactant (at balance between lipophilicity and hydrophilicity, or HLB temperature).

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C„E;„(9.09wt%)

• : Clouding point O : Solubilization phase boundary 0

0.1

0.2

0.3

0.4

0.5

Weight fraction of hexadecane Fig. 7.5. Equilibium diagram of non-ionic surfactant-hexadecane-water.

It is also clear that for surfactants with similar HLBs, the amount of solubilized oil increases with increase in the alkyl chain length, by comparing the solubilization produced by two surfactants such as hexaethylene glycol monododecyl ether (C12E6) and octaethylene glycol monohexadecyl ether (C16E8). It can also be seen that the most appropriate HLB of surfactant also changes according to the structure (properties) of the oil to be solubilized. In order to solubilize the maximum amount of oil, it is clearly best to use a surfactant with the most appropriate HLB which has a long alkyl chain if at all possible. This solubilization phenomenon is also shown by non-aqueous solutions of surfactants, and in this case, reverse micelles are formed in nonaqueous solutions and aqueous solution is solubilized. 7.1.3.2. Microemulsions Shulman et al.^^^ observed that when oils, water, an ionic surfactant and a middle-chain alcohol are mixed together, a transparent system is formed spontaneously; they called it a microemulsion. Recently, in the field of colloid science, microemulsions have been defined!^) as thermodynamically-stable single-phase systems with oil, water and amphiphile(s) which are transparent or semi-transparent and the dispersion with large swollen micelles. Accordingly, they are essentially similar to the solubilization systems described above but they are characterized by the large amounts of solubilized oil or water; the solubilization shown in Fig. 7.5 can be called a microemulsion. The term microemulsion is not always used strictly according to this definition and it is sometimes used to describe transparent or semi-transparent emulsions with extremely small particles but not solubilization systems. 7.1.4. Emulsions A disperse system of two mutually-insoluble liquids is called an emulsion and the process of producing this system is called emulsification. Although emulsions belong to the class of disperse colloids or coarse dispersions, they are thermodynamically-unstable

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and eventually separate. Emulsions are usually opaque. This is because the refractive index of the dispersion medium differs from that of the dispersion phase; the particle diameter is usually greater than 0.1 jum. If the refractive indices are the same, even emulsions with large particle diameters are transparent. The most important problem with emulsions is how to manufacture emulsions that are stable over the long term. Emulsions are an important technology in production of cosmetics and are described in some detail in the following section. 7.1.4.1. Emulsion types Emulsions are formed from two phases: the dispersion medium (continuous phase) and the disperse phase (emulsion particles). They are classified into two types: oil in water emulsions (O/W), and water in oil emulsions (W/0). Generally, in a hydrophilic emulsifier, the water phase is the continuous phase forming an O/W emulsion; in the lipophilic case, oil is the continuous phase forming a W/0 emulsion. Whether an O/W or W/0 emulsion is formed is determined by which of the two emulsion types is more stable^^^ To put it simply, if the micelles are formed in the aqueous phase, an O/W emulsion is formed; if reverse micelles are formed in the oil phase, a W/0 emulsion is formed^^\ The orientation of the surfactant adsorped at the oil-water interface easily becomes the same as the orientation of the surfactant in micelles in a stable system. In other words, if the micelle is formed in the water (oriented with hydrophilic groups on outside and lipophilic groups on inside), the O/W emulsion is considered stable because the surfactant in even a drop of the emulsion is oriented with the hydrophilic groups on the outside and the lipophilic groups on the inside. Whether or not the emulsion type is O/W or W/0 can be seen from the difference in the properties of the continuous phase using the methods outlined below. (1) Electrical conductivity. The electrical conductivity of O/W emulsions is higher than that of W/0 emulsions. (2) Dilution method. This method evaluates the emulsion type from the dispersion ease at dilution with water. (3) Dye method. This method evaluates the emulsion type by dissolving water-soluble and oil-soluble dyes in the emulsion. In addition to simple O/W and W/O emulsions, there are also multiple emulsions or double emulsions such as W/O/W and 0/W/O emulsions. When these types of emulsions are observed under a microscope, more particles can be seen within the emulsion particles. 7.1.4.2. Preparation method The methods for making emulsions are basically the same as for making colloids: the condensation method, and the dispersion method. In the former, a supersaturated state is formed by some method from the dissolved state and then the disperse phase is deposited. In the latter method, a large disperse phase aggregate is forcibly broken down into finer particles; this method requires energy to increase the interface. Emulsions are generally made by the dispersion method. As actual examples, one simple method uses the shear force of an emulsification machine; another method uses interface science to achieve the same results without the need for large energy input. As emulsification equipment is described in the section on equipment for manufacturing

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cosmetics, only the interface science method is described here (including the condensation method for ultra-fine emulsions). To produce an 0/W emulsion using interface chemical characteristics, in simple terms, a fine emulsion is obtained by lowering the interface tension and performing emulsification. In other words, the particles are made as small as possible using the smallest amount of energy by making use of interface-chemical processes. However, if the stability of the emulsion becomes worse when the interface tension is low, some procedures are used after emulsification to change to a stable system. Various procedures and processes for achieving this result have been reported including the HLB temperature emulsification method (phase inversion temperature emulsification^'^^^^), nonaqueous emulsification^^^ phase inversion emulsification^^^ surfactant (D) phase emulsification ^^>, liquid crystal emulsification^^^ etc. The methods discussed so far are for producing O/W emulsions with a particle size at the submicron level or greater than 0.1 //m. However, there are also methods for producing transparent and semitransparent emulsions (ultrafine emulsions) with a particle size below 0.1 //m. In external appearance, these emulsions seem the same as microemulsions described earlier, but the equilibrium phase diagram shows a dual liquid phase system and such emulsions simply have an extremely smaller particle size than that of normal emulsions. These emulsions can be produced by cooling of the microemulsions formed in non-ionic surfactant-oil-water systems at high temperature (Fig. 7.5). This procedure is included in the condensation method described above. However, as the emulsion particles are extremely small, such emulsions are more readily rendered unstable by Ostwald ripening (described in Section 7.1.4.3) than normal emulsions. Good stability can be obtained by selecting the suitable oil to use. In this production method, since there is a linear relationship between the ratio of the oil and surfactant and the diameter of the emulsion particles, an advantage is the ability to control the particle diameter by changing the ratio of the oil and surfactant. There are comparatively fewer reports on W/O emulsions than O/W emulsions. There are the gel-emulsification method and emulsification methods using clay minerals. In the former method, aqueous solutions of amino acids or their salts and aqueous solutions of reduced sugars such as sorbitol and multitol are added by stirring into a hydrophobic surfactant comprised of a fatty-acid partial ester of a polyvalent alcohol with three or more hydroxyl groups to create a stable gel including the aqueous solution in the surfactant. When oil and then water are added to this gel, a W/O emulsion is produced. The method using amino acids^^^ was reported in detail. The method of forming W/O emulsions^^) using water-swelling clay minerals is as follows. First, quaternary ammonium organic cations and non-ionic surfactants are intercalated into water swelling clay minerals to form new clathrate compounds. These complex compounds do not swell at all in water but they swell easily in oils to form viscous oil gels. When water is mixed into such a gel, an extremely-stable W/O emulsion is formed. These are quite different from the normal emulsions produced using usual surfactants so far and the emulsion particles are thought to be microcapsules formed with clay complexes. 7.1.4.3, Stability As described above, emulsions are essentially unstable and they break down when left untouched over long periods. Generally, this process can be broadly classified into three

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phenomena: (1) creaming; (2) coagulation; (3) coalescence, as shown in Fig. 7.6. Ostwald ripening also occurs too. These phenomena are not restricted only to emulsions; they also generally occur in disperse colloids. (1) Creaming. In an OAV emulsion, the oil is the disperse phase, so the particles float when the specific gravity of the oil is lighter than that of water. (In a W/O emulsion, they sedimentate.) The velocity is found from Stokes' Law represented by Eq. (3). v - 2 g (pi-p2)r^ 9;;

(3)

where V is the velocity at which the particles move, g is the acceleration due to gravity, r is the particle radius, pi andp2 are the density of the dispersion medium and disperse phase, respectively, and rj expresses the viscosity of the dispersion medium. Consequently, to delay the creaming velocity, it is good to have a small particle diameter, a small difference in the densities of the dispersion medium and disperse phase, and a dispersion medium with a high viscosity. As a result, clearly, one important technological issue in producing emulsions is achieving small emulsion particle size (refer to Section 7.1.4.2). In addition, since creaming is affected by coagulation and coalescence described below, creaming sometimes evaluates complex stability. (2) Coagulation. A general force of attraction acts between colloid particles and when there is no force of repulsion acting between the particles, the particles tend to coagulate. The repulsive force acting between colloid particles is believed to be due to electrical charge and macromolecular adsorption.

Creaming V

N

f

J

N

Coagulation

L

J

Initia [ Dispersioi State

y////////A Coalescence

^

)

Fig. 7.6. Three types of separation exhibited by emulsions.

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The DLVO theory^^^ can be applied to electrical repulsion systems. The general London-van der Walls attractive force, VA* is created between particles. On the other hand, a diffusion electrical double layer is formed around particles with a charged surface, and, as the particles approach, the electrical double layer overlaps to generate the electrostatic repulsion potential VR. These attraction and repulsion forces are functions of the distance between particles. When the particles get close, the total potential energy, Vj, which is the sum of V^ and VR determines whether or not the force acting between the particles is attractive or repulsive. (4)

VT=VA+^R

This relationship is shown qualitatively in Fig. 7.7. As the electrostatic repulsive force gets stronger, Vj curves as shown in the figure; as the particles get closer, the repulsive force acts and energy barrier (the peak of Vj) is formed and coagulation can occur when the kinetic energy of particles overcomes the energy barrier in this region. If this barrier (peak) becomes sufficiently bigger than the potential of thermal motion, kT, coagulation does not occur. When the height of the peak falls to about the same level as kT, the particles slowly coagulate. In addition, the SchultzHardy law which describes that coagulation proceeds more rapidly with increase in concentration and valency of ions in the solutions is explained by the DLVO theory, because the electrostatic repulsion force decreases in inverse proportion to the ion valency and the root of ion concentration. This theory is very important in emulsions, particularly systems emulsified using ionic surfactants, and if there is sufficient repulsive force in the system, the emulsion is stable for coagulation.

w o

Distance between Particles

Fig. 7.7. Particle interaction.

(Closer)

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It has long been known that polymers increase the dispersion stability of colloid particles. This phenomenon is thought to be due to the creation of a repulsive force caused by the overlap of a polymer layer adsorped on the surface of the colloid particles. This type of effect is known as the osmotic effect or the volume restriction effect^^). In simple terms, the repulsive force occurs because the osmotic pressure is generated at overlap of the adsorped layer of polymer with increase in polymer concentration as the result; dispersion medium penetrates the overlap and particles are pulled apart. Additionally, this explanation is also believed to apply to the stability of O/W emulsions prepared using non-ionic surfactants^^) explaining the greater stability produced by using a surfactant having a large mole number of added ethyleneoxide. This is an extremely important subject in considering the stability of non-ionic surfactant emulsions. (3) Coalescence. The term coalescence describes an aggregation in which the emulsion particles form an homogenous fusion. If the coalescence proceeds completely, the emulsion separates into two phases, which is the most stable state. Coalescence differs from creaming and coagulation in physical meaning. If an emulsion is stable against coagulation, then the coalescence cannot also occur and for this point coagulation theory can be applied to coalescence. Although the emulsion particles coagulate, the coalescence does not always occur. This is because coalescence occurs with the removal and breakdown of adsorped layers of the oil-water interface. Hence, it tries to increase the coalescence resistance by reducing the fluidity of the adsorped layer and forming a liquid crystal at the interface. Davies^^^ examined the structure of surfactants preventing coalescence from the role of the adsorped layer of surfactant in droplet fusion, discovering that surfactants having stronger lipophilic and hydrophilic properties are better. However, there may still be no clear explanation for coalescence. (4) Oswald ripening. So far, the focus has only been on coalescence as a cause of increasing particle size in emulsions, but recently, a phenomenon called Ostwald ripening has come to attention. In Ostwald ripening, when the particle diameter has a size distribution, the small particles become smaller and the large particles become larger and finally the small particles seem to disappear. This can be explained by Kelvin's law shown in Eq. (5). lnS,/S2=^(l/r,-l/r2)

.^.

where. Si and 52 are the solubilities of the particles of radius rj and r2, respectively, y is the interface tension, V is the molar volume of the disperse phase, R is the gas constant, and T is the absolute temperature. This equation shows that the solubility of a small oil droplet is larger than the solubility of a large oil droplet, explaining the diffusion of oil from small particles to large particles via the aqueous phase described above. Ostwald ripening has been reported as occurring in normal emul3JQjis28,29) aj^j i\\txt is a detailed explanation^^). When the particle size is smaller

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than 100 nm, the above equation shows that the phenomenon called Ostwald ripening becomes more important. Recently, the importance of Ostwald ripening has become clear in the production^^D of ultra-fine emulsions (refer to Section 7.1.4.2). 7.7.5. Liposomes

(vesicle)

When an amphiphilic lipid such as lecithin forming a lamellar liquid crystal is dispersed in an excess of water, small capsules formed of bilayer membranes are easily created. These capsules are called liposomes or vesicles. If lamellar liquid crystals are formed by lipids, the hydrophobic lipid group is not restricted to two chains and vesicles can be formed with both mono-^^^ and tri-chain^^^ amphiphilic lipids. These vesicles differ from micelles in not being thermodynamically-stable, so it is possible to form vesicles of different sizes and structures depending on the production method. There are multilamellar vesicles having multiple layers formed from many sheets of bilayer membranes; there are small unilamellar vesicles formed from single-sheet membranes, and there are large unilamellar vesicles formed from single-sheet membranes. The vesicles have properties similar to microcapsules due to their structure and they have been tested for use in both the pharmaceutical and cosmetic fields. When they are used as products in their fields, it is necessary to pay attention to stability. 7.7. (5. Properties of powders The purpose of powders used in cosmetics is to impart color to the skin, to hide pigmented spots such as liver spots and ephelides, and to absorb perspiration and skin lipids. In addition, they are also used as support for perfumes, etc., and mild abrasive powders are used in toothpastes. The cosmetic products in which powders are used take various forms such as powders themselves, pressed powders, suspensions, and solids in which they are dispersed in solid lipids, etc.. This section explains how the properties of powders affect the properties of these types of product. The factors affecting the stability of suspensions are the same as those affecting disperse colloids and coarse dispersions (refer to Section 7.1.4). 7.7.6.7. Specific surface area The form of powder particles is quite variable so the size definition based on particle diameter is quite difficult. Consequently, the specific surface area, which is the surface area per unit weight or unit volume of the powder is commonly used as one measure of the size of powder particles. The specific surface area is found by measuring gaseous monomolecular absorption weight per unit weight of the powder^^^ 7.7.6.2. Apparent density The apparent density is the density calculated from the weight and cubic volume of the powder and it also includes the free space within the powder. It is also sometimes called the bulk density. The cubic volume of a unit weight of packed powder is also called the specific volume. The apparent density is measured by various packing methods^^^.

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7.1.6.3. Packing characteristics The packing characteristics of powders are expressed by the bulk density and specific volume described above, but porosity is also widely used. Porosity is expressed as shown below. Porosity = 1 -

Apparent Density True Density of Powder Particles

(6)

If the spheres are all the same size, the porosity can be calculated from the packing form (the way in which the particles are arranged) but there is no relationship with particle size. However, there is actually a relationship with the specific surface area and particle diameter; when the particle diameter becomes smaller than the inherent particle size (critical particle diameter), the porosity increases. This is because as the particle diameter decreases, interactions between particles (adhesion and coagulation, etc.) increase. 7.1.6.4. Flowability Powders range from those that flow easily and feel smooth to those that do not flow well and feel sticky. This difference in flowability is due to differences in the adhesion and coagulation of powders. The causes of adhesion and coagulation are believed to be van der Walls force acting between particles as well as static electric charges and capillary force due to the surface tension of water adhering to the particles. A number or parameters such as angle of repose, friction factor, and run-off velocity, etc., are used to evaluate flowability. This section describes the angle of repose method. When a powder is dropped onto a vibration free horizontal surface it forms a pile as shown in Fig. 7.8; the angle formed by the slope of the pile to the surface is the angle of repose. However, in some -^ases, when the pile takes the form of a curved or an irregular

/////////////////////////// a. High flowability powder

//////////////////////// b. Low flowability powder

b'. Fig. 7.8. Various forms of powder piles.

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slope, as shown in Fig. 7.8a',b' in the figure, the angle between the slope and the surface is smaller or greater than the theoretical angle. In these cases, it is better to measure H and D and calculate the angle. In measuring the angle of repose, obviously, the formation method of the pile is important, and there are a number of methods including: point supply method, cylinder draw-up method, parallel plate method, container inclination method, elimination angle method, sifter method, and rotating cylinder method. 7.1.6.5. Wettability When a water droplet rests on a horizontal surface made of a large polished solid, the droplet either spreads out and wets the surface, or the droplet remains a droplet and does not wet the surface. If oil is substituted for the water, the wettability of the oil is observed. Fig. 7.9 shows how the liquid droplet is formed. The angle {6) formed by the solid surface to the tangent at the contact point between the droplet surface and the solid surface is called the contact angle. This contact angle is one measure of the wettability of the solid by the liquid and it is a very important index used in mixing powders and liquids. However, it is not practically possible to measure the contact angle of powder particles directly, so the measurement is made by compressing the powder into a solid surface. 7.1.6.6. Surface modification The surface properties of powder particles can be changed by any of a number of methods. This is called surface modification. The objectives of surface modification in the cosmetics field can be broadly split into two: changes in chemical properties such as the particle surface catalytic action, and changes in the physical properties such as the dispersion medium wettability, etc. Many surface modification processes have been developed to date. Recently, an interesting surface modification method has been developed: ultra-thin films of polymers have been formed on powder surfaces from silicone monomers by using the powder surface catalytic action. This surface modification^'^^ can decrease the surface catalytic activities which cause color fading and fragrance changes. In addition, functional molecules can be introduced on these ultra-thin film surfaces of these modified powders which not only changes the physical properties of the powder surfaces but also adds new functional properties to the powders. This technology has applications beyond cosmetics such as packing materials for high-performance liquid chromatography. Air

Solid

Solid

a. d<%°

b. ^>90°

Fig. 7.9. Liquid-solid contact angles.

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7.2. Rheology of cosmetics 7.2.1. Meaning of rheology in cosmetics Rheology is a scientific discipline dealing with changes in the form of things and with the dynamics of flow. The simplest rheological properties are viscosity and elasticity. Liquids such as water and liquid paraffin have viscosity but not elasticity. These types of materials are called Newtonian fluids. Newtonian fluids flow under even the smallest force, spending all the force in flowing and thereby consuming the energy. By contrast, things such as rubber and a metal spring have elasticity but not viscosity. These types of materials are called Hookian bodies. When a force acts on a Hookian body, the force is spent to change the shape of the body and the energy is stored instead of consumed. In cosmetics, the liquid state is usually handled as a Newtonian fluid, but some disperse systems such as milky lotions and creams demonstrate complex rheological properties incorporating both viscosity and elasticity. These types of materials are called viscoelastic bodies. The rheological properties of a material depend on its internal structure and are extremely important in cosmetic disperse systems. Rheological measurements are very useful in clarifying the internal structure of cosmetics. In addition, knowledge of the rheological properties of cosmetics is essential in designing cosmetic manufacturing machinery. Rheology of cosmetics is also important for usage standpoint. Cosmetics such as pomades, hair sticks and massage creams, depend upon tackiness and lubrication. Body powders use the lubrication effect of talc powders. In addition, attempts have been made to attach a rheological significance to characteristics that can be sensed by people like the extensibility and feel when using creams, etc., and the feel of hair after using shampoos and rinses. G. W. Scott Blair^^) coined the term psychorheology for this field. Moreover, research into the rheology of skin has seen some recent advances. 7.2.2. Flow forms First, the flow of a Newtonian fluid is considered. As shown in Fig. 7.10, the Newtonian fluid can be represented as flowing between two parallel surfaces of A cm^ separated by a distance of x cm. The under surface is fixed and a force of F dynes is applied in the direction of the arrow to the upper surface causing the surface to move at a velocity of u

Velocity = u I

Velocity = 0 Fig. 7.10. Newtonian fluid model.

^F

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Newtonian flow Bingham flow Plastic flow Pseudoplastic flow Dilatant flow Ostwald flow Shear stress Fig. 7.11. Various flow modes.

cm/s. Each layer of liquid between the two surfaces flows at the velocities shown by the arrows and ulx is constant. This value is proportional to the force per unit area {FIA) applied to the upper surface. The viscosity of the fluid, r], is found from Eq. (7).

u/x

(7)

FIA is called the shear stress, ulx is called the shear rate. The viscosity, r], is expressed in dyne sec/cm^ and is called the poise. The viscosity of water at room temperature is 1 centipoise. The Newtonian form of the flow is rare for a disperse system and various other forms such as Bingham, plastic, pseudoplastic, dilatant, and Ostwald flow have all been observed. These are shown in Fig. 7.11. When measuring the viscosity, an external force is applied to the system and this external force can change the structure of the system. Even if the shear stress (external force) is constant, the viscosity decreases with time during measurement and when the shear stress is removed, it returns to the original state. This effect is called thixotropy. When an external force is added to the system, it becomes solid, and when the force is removed, it returns to the original state. This property is called dilatancy. All the above phenomena are commonly seen in dispersed systems, and consequently, the measured viscosity of cosmetics varies greatly depending on the measurement method. Looking at this in another way, rheology measurement by a variety of methods is useful in clarifying the internal structure of cosmetics. 7.2.3. Rheology measurement methods^^^ In simple terms, the basic principle of rheology measurement involves obtaining the velocity at which a body flows as a function of the force required to make that body flow.

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However, when a force is applied that makes the material flow at a velocity greater than the velocity at which it can flow, even a Newtonian fluid exhibits elasticity, so the size of the shear rate becomes important. In disperse systems, when they are deformed largely, in many cases the particle dispersion changes accordingly. As a result, it is essential to select the most appropriate measurement method according to the measurement purpose. There are some measuring instruments used from the practical viewpoint although the measured values have no clear meaning. The following explains some rheology measuring instruments used both in laboratories and plants. 7.2.3.1. Capillary viscometer Typical viscometers are the Cannon-Fenske, and Ubbelhode viscometers based on the Ostwald type. The glass capillary has the form shown in Fig. 7.12; the time taken for a fixed amount of the test material to flow by gravity through a capillary from the upper measurement bulb to the lower test material bulb is measured. This system is best for measuring fluids such as lotions and liquid paraffin. It is used to determine the viscosity of liquids used to calibrate other viscometers. 7.2.3.2. Orifice viscometer This viscometer is composed of a tank with a small hole through which the test material flows. The time taken for a fixed amount of the test material to flow through the hole is measured. The Redwood and Saybolt viscometers are used to measure the viscosity of liquid paraffin, etc. There is also a type using extrusion under pressure which is best for measuring lipsticks and pomades, etc. 7.2.3.3. Rotating spindle viscometer In this meter, a rotating spindle is inserted in the test material and the additional resistance is measured by a spring. In commercial models, the speed of rotation can be switched and several types of spindle ranging from a thin rod (for high viscosities) to a round plate (for low viscosities) are available. This type of viscometer is used for emulsions and nail enamels.

Fig. 7.12. Capillary viscometer.

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"D -Torsion Wire

• Inner Cylinder (B) •Test Material 1-^- Outer Cylinder (A) Fig. 7.13. Rotating cylinder viscometer.

7.2.3.4. Rotating cylinder viscometer As shown in Fig. 7.13, this viscometer consists of a cylindrical container (A) and an inner concentric cylinder (B) connected to a torsion wire. The test material is placed between the inner and outer cylinders and when the outer cylinder is slowly rotated, the inner cylinder and the test material rotate in the same direction as the outer cylinder. The rotation of the inner cylinder is resisted by the torsion wire and the inner cylinder stops at the angle of rotation where the force applied from the test material and the torque of the torsion wire are in equilibrium. The viscosity of the test fluid can be found from the size of this angle of rotation. When the angle of rotation of the torsion wire is measured with increasing speed of rotation of the outer cylinder and then is measured by decreasing it, the curve plotting the angle against the rotation speed shows the hysteresis in some samples (thixotropy and dilatancy).

Recovery

Creep

1

/\

[E \ ^^''

/N

o U a a;

l___^^-d

1 F

/c //

S-i

U

t il

J^

/» B

|A

y. '1 Time (t) Fig. 7.14. Creep curve.

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7.2.3.5. Creep measurement When the outer cylinder is fixed and a constant torque is applied to the top end of the torsion wire, it is possible to measure the creep. Products with viscosities similar to creams and milky lotions show viscoelasticity at the low shear rate due to the mutual interaction between particles. Fig. 7.14 shows the result of creep measurement of a sample. In this figure, the ordinate is creep compliance and the abscissa is time. The creep compliance is the ratio of the strain to the stress. When a constant stress is applied to a sample with the torsion wire, the sample generates a strain and the curve A, B, C, D is obtained as a function of creep compliance against time. In addition, when the stress is removed at point D, the recovery is shown by the curve D, E, F. The instantaneous elasticity {E^, retardation elasticity (£'R), and viscosity {rjN) are determined by analyzing these curves. Since many cosmetics are disperse systems, they have both viscosity and elasticity and this method is useful for measuring the properties of these types of cosmetics. 7.2.3.6. Cone plate viscometer In this viscometer, the test material is inserted between a cone and a plate as shown in Fig. 7.15. The plate is turned by a motor and the additional resistance to the cone is measured by a spring. This equipment is useful for measuring the viscosity of materials ranging from milky lotions to creams by changing the size of the cone and the strength of the spring. Some viscometers are designed to measure viscosity by automatically increasing the rotation of the cone at a constant rate and then measuring as the rotation decreases. This type of equipment is useful for measuring materials such as cosmetics showing complex viscosity changes. 7.2.3.7. Forced vibration coneplate viscometer In this viscometer, the cone does not just rotate in one direction, it also oscillates. This is called a dynamic measurement method. It has the advantage of being able to measure extremely small deformations. In addition, when auxiliary equipment is used, it is possible to measure the Weisenberg effect shown by elastic materials.

Spring

-Cone Test Material - Plate

Fig. 7.15. Coneplate viscometer.

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Oscillator 1

1

Strain

Stress

1

Linear Amplifier

Strain Amplifier

J

Decade Filter

1

Waveform Storage Device

#

Interface

Computer

I

Oscilloscope Fig. 7.16. Skin viscoelasticity meter (in vivo)^^\

7.2.3.8. Parallel-plate plastometer This viscometer is used to measure creep described in Section 7.2.3.5. The test material is squeezed between two flat parallel plates and a load is added to the upper plate. The rate at which the thickness of the test material decreases with load is measured. 7.2.3.9. Penetrator Although this is called a viscometer, it should perhaps be called a hardness meter. The force required for a needle or the tip of a rod to penetrate the test material is measured. This type of viscometer is useful for measuring the hardness of stick-type cosmetics and soaps, etc. The next three items do not deal with the rheology of cosmetic products. Instead they explain equipment for measuring the viscoelasticity of skin, and the usage sensibility of shampoos and rinses. 7.2.3.10. Skin viscoelasticity meter (in vivo) In this method, a small attachment is applied to the skin and the shear stress is measured by applying sine-wave oscillation in a linear direction through a mechanical linkage^^) (Fig. 7.16). During measurement, a sensor is pressed on the skin at a constant pressure Outlet

Hot Water Inlet

A : Pressure Tap B : Pressure Tap

AP : Pressure Loss

C : Hair Strand Fig. 7.17. Hydraulic hair friction force meter^^l

Cosmetics and physical chemistry

V Clamp

Hair Strand

x / v ^ l x

189

^Q"f ^"^ Pressure

A

B,B' constant number of revolutions

Fig. 7.18. Hair friction measuring instrument^^^

and the viscoelasticity is found by measuring the shear stress of the skin corresponding to a cyclical force applied according to the sensor signals. However, when pressure is applied to materials like skin, they are compressed and the mechanical properties change, so it is necessary to handle the viscoelastic value as a function of applied pressure. Since a pressure sensor fitted to the equipment is able to constantly monitor the pressure applied to the skin, it is possible to accurately measure the viscosity by treating it as a function of applied pressure. 7.2.3.11. Hydraulic hair friction force meter^^^ This equipment is for measuring the "roughness" or "smoothness" of hair at rinsing. Measurement is performed as shown in Fig. 7.17. The pressure drop, AP, occurring between points A and B when water is flowing, corresponds to the friction resistance between the hairs themselves; the smaller the value of AP, the smaller the friction between hairs at rinsing, meaning that the hair is not rough. 7.2.3.12. Hair friction measuring instrument^^^ The hair friction measuring instrument was developed to evaluate the smoothness of hair when touched by hand. The hair strand is fed through spongy rollers (NBR) and the friction force is measured as shown in Fig. 7.18. The results show good agreement with sensory evaluation tests.

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Clayton, W.: Theory of Emulsions, 5th edn., p. 178, J. & A. Churchill, London, 1954. Griffin, W. C : J. Soc. Cosmet Chem., 1, 311 (1949). Griffin, W. C : J. Soc. Cosmet. Chem., 5, 249 (1954). Davis, J. T.: Proc. 2nd Int. Congr. Surface Activity, 1, 426 (1957). Kawakami: Kagaku, 23, 546 (1953). Shinoda, K.: Nippon Kagaku Kaishi, 89, 435 (1968). Shinoda, K., Nakagawa, T., Tamamushi, B., Isemura, T.: Colloidal Surfactants, p. 17, Academic Press, New York, 1963. Preston, H.: J. Phys. Coll. Chem., 52, 85 (1948). Tomomasa, Kouchi, Nakajima: Yukagaku, 37, 1012 (1988). Shinoda, K., Saijo: Yukagaku, 35, 308 (1986). Prince, L. M.: Microemulsions, Preface, Academic Press, New York, 1977.

190 New cosmetic science 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39.

Davies, J. T., Rideal, E. K.: Interfacial Phenomena, 2nd. edn., p. 371, Academic Press, New York, 1977. Harusawa, F., Saito, T., Nakajima, H., Fukushima, S,: J. Colloid Interface Sci., 74, 435 (1980). Shinoda, K., Saito, H.: J. Colloid Interface Sci., 30, 258 (1969). Shinoda, K., Freberg, S.: Emulsions and Solubilization, Wiley, New York, 1986. Mitsui, T., Machida, Y., Harusawa, F.: Am. Perfum. Cosmet., 87 (1972). Suzuki, T.: Japan Patent, 57-29213 (1982). Sagitani, H.: J. Am. Oil Chem. Soc, 58, 738 (1981). Sagitani, H.: J. Dispersion Sci. TechnoL, 9, 115 (1983). Suzuki, T., Take, H.i., Yamazaki, S.: J. Colloid Interface Sci., 129, 491 (1989). Nakajima, Tomomasa, Kouchi: J. Soc. Cosmet. Chemist Japan, 23, 288 (1990). Kumano, Y., Nakamura, S., Tahara, S., Ohta, S.: J. Soc. Cosmet. Chem., 28, 285 (1977). Yamaguchi, M.: Yukagaku, 39, 95 (1990). Kitahara, Furusawa: Bunsan Nyuka no Kagaken, p. 104, Kogaku Tosho, Tokyo, 1979. Kitahara, Furusawa: Bunsan Nyuka no Kagaken, p. 202, Kogaku Tosho, Tokyo, 1979. Florence, A. T., Rogers, J. T.: J. Pharm. Pharmacol., 23, 153 (1971). Davies, J. T., Rideal, E. K.: Interfacial Phenomena, 2nd. edn., p. 366, Academic Press, New York, 1977. Higuchi, W. I., Misra, J.: J. Pharm. Sci., 51, 459 (1962). Davis, S. S., Round, H. P., Purewal, T. S.: J. Colloid Interface Sci., 80, 508 (1981). Kabal'nov, A. S., Pertzov, A. V., Shchukin, E. D.: Colloids Surfaces, 24,19 (1987). Imae, T., Trend, B.: J. Colloid Interface Sci., 145, 207 (1991). Tanaka, M., Fukuda, H., Horiuchi, T.: J. Am. Oil Chem. Soc, 67, 55 (1990). Kubo, Jimbo, Mizwatari, Takahashi, Hayakawa: Funtai Riron to Ouyo, Maruzen, Tokyo, 1979. Fukui, H.: Yukagaku, 40, 10 (1991). Scott Blair, G. W.: A Survey of General and Applied Rheology, Pitman, London, 1949. Sherman, P.: Industrial Rheology, Academic Press, London 1970. Umeya, J.: J. Biorheology Soc. Jpn, 4, 34 (1990). Fukuchi, Okoshi, Murotani: J. Soc. Cosmet. Chemist Japan, 22, 15 (1988). Fukuchi, Tamura: J. Soc. Cosmet. Chemists Jpn., 25 (3), 185 (1991).

8

Stability of cosmetics

Like other products, the stability of all cosmetics must be matched to the expected period of usage by the consumer as well as to the user's requirements. It is important to guarantee product quality by paying sufficient attention to the time required to distribute the product from the manufacturer to the consumer and to the actual usage period. Recently, it has not been sufficient to simply guarantee the feeling on use and performance; it has also become important to consider the safety and stability in usage as well as the disposal after use. The first half of this chapter describes the stability of base formulae and pharmaceutical agents at the research and production stages. The latter half describes the stability aspects of base formulae and containers in consideration of quality assurance for products when they are actually used. Guaranteeing the stability of cosmetics requires sufficient evaluation at the R&D stage as well as the establishment of design principles for the product itself.

8.1. Stability of base formulae and its testing To ensure that the various functions of cosmetics are realized, the first stage is to observe whether or not there are any changes in their physico-chemical properties. (1) Chemical changes: color change, color fading, fragrance change, staining, crystallization, etc. (2) Physical changes: separation, sedimentation, aggregation, blooming, sweating, gelling, unevenness, evaporation, solidification, softening, cracking, etc. These phenomena not only have a great effect on usability, but also make cosmetics unattractive and damage their image. Generally, the quality of cosmetics must be guaranteed until the consumer finishes them and manufacturers work on this assumption while focusing their research effort on improving the overall level. Guaranteeing product life helps greatly in securing consumer confidence. 8,LL

General preservation

tests

8.1.1.1, Temperature stability test In this test, cosmetics are tested at different temperatures to observe and measure the changes in the properties of samples with the lapse of time. (1) Test temperatures: -10°C, -5°C, 0°C, 25°C, room temperature, 30°C, 37°C, 45°C, 50°C, 60°C, etc. The most appropriate temperature is selected according to the sample properties. 191

192

New cosmetic science

(2)

Preservation period: 1 day to 1 month, 2 months, 6 months, 1-3 years, etc. The most appropriate period is chosen according to the sample monitoring purpose. (3) Observed items', changes in external appearance (color changes, color fading, color unevenness, foreign substances mixing, scratching, suspended materials, separation, sedimentation, sweating, blooming, crystallization, cracking, gelling, transparency, caking, luster, subsiding, capping, pinholing, aeration, mold growth, etc.); changes in fragrance: (direct observation, transfer of container odor, on use) (4) Measurement items and typical measuring instruments. pH: glass polarity pH meter Hardness: curd tension meter, Bikas hardness meter, Olsen hardness meter, rheometer, etc. Viscosity: Brookfield viscosimeter (B, H, E types). Redwood viscosimeter, Ferranti Cone and Plate viscosimeter, etc. (refer to Section 7.2) Turbidity: integrated spherical turbidity meter, concentrated light source method Particle diameter: microscope, colter counter, standard flay, grind meter Emulsion type: tester (volt-ohm-milliammeter) Softening point: Webrode method. Boiling method Water evaporation: desiccation method, Karl Fischer method, evaporation method (5) Evaluation: data for the above items is recorded over time and any abnormalities observed in the samples are used as feedback for the the formulation design. Generally, the stability range of observed items is determined by standardized evaluation methods such as the five point and O (good), X (bad) indications methods. Changes in viscosity with time and temperature indicate the gelling of emulsions while the changes in particle diameter indicate the states of coalescence, creaming and coagulation. These data make it possible to achieve a more stable balance in formulations. The noteworthy points in these observations as well as in the accelerated preservation tests described below are to ensure that the quality of materials for containers used in the preservation tests is the same as that for containers used in the market. The second most noteworthy point is to consider the decrease in amount of the cosmetic with use and to ensure that the stability is guaranteed in accordance with the usage method right until the end. The formulation and container must ensure the absolute minimum change in the functions and performance of the cosmetic throughout its usage life. 8.1.1.2. Photo-stability tests (light resistance) Cosmetics are often exposed to varying degrees of light in shop windows and they can be subject to direct strong sunlight or artificial light for long periods of time. Except for a few displayed in cases, most are displayed without their cases. Consequently, it is very important for cosmetics to be photo-stable. At present, the following methods are used to test and guarantee photo-stability. (1) Outdoors (sunlight) exposure test. Although there is no standard test, the changes in samples over a number of days, weeks, and months based on exposure to midsummer sun are observed. The observed items are usually changes in color and fragrance as described in item (c) of Section 8.1.1.1.

Stability of cosmetics

(2)

(3)

193

Inside (artificial light) exposure test. Since it is often difficult to monitor changes under fixed condition outdoors due to seasonal changes and the occurrence of rain, snow and mist, in many cases, the tests are performed using artificial light with a spectrum close to natural sunlight. A typical method uses a carbon arc fade meter and a xenon fade meter. The xenon arc lamp is an artificial light source producing a light spectrum very close to that of natural sunlight. The light source is composed of a long xenon arc tube and an infrared water filter. It has a water jacket and the main body (light source and sample stage) and the internal temperature can be adjusted between room temperature +15° and +80°C; the black panel temperature can be adjusted between 30° and 80°C. The sample is exposed to the light by mounting it in a rotating frame holder. The rotating frame circles around the xenon lamp and exposes the sample to the light. The rotation speed is constant and the total exposure is determined using a time switch; the distance of the sample from the lamp can be adjusted between 25 and 40 cm. Normally, samples are observed for fixed time periods at room and higher temperatures and the stability is evaluated as the degree of color change (AP) compared with controls (unexposed samples). Fig. 8.1 shows the spectra of sunlight, the carbon arc lamp and the xenon lamp (with filter) as well as the relative optical energy. The xenon arc lamp is an excellent light source having the same UV and visible light spectrum and energy levels as sunlight; the light color is white. Table 8.1 shows the relative similarity of sunlight, the xenon lamp and carbon arc lamp in the 300-400 nm band, which has the largest effect on color change; if the energy level of the 300-400 nm band is 1, the ratio of the energies in the 300-340 nm band and the 300-360 nm band is very similar for each type of light. Fluorescent light exposure test. This test is based on the idea that cosmetics are often exposed to light from fluorescent tubes in show cases. The hours of light exposure in 1 day is calculated and the color change over the required number of days exposure is observed.

Xenon lamp with filter Carbon arc lamp

1100 Wavelength (m/z) Fig. 8.1. Optical spectrum of sunlight, xenon lamp and carbon arc lamp.

194 New cosmetic science Table 8.1. Relative similarity of sunlight and different light sources in UV region

^^^^^^^^

Light Source

Wavelength (nm) ^ ^ ^ ^ ^ ^ ^ ^ 300—340 300—360 300-400

Sunhght

Carbon Arc

Xenon

0.20 0.44 1.00

0.18 0.33 1.00

0.18 0.37 1.00

S. 7.2. General performance and effectiveness tests The temperature and photo-stability tests described in items Section 8.1.1 are used to evaluate any deterioration in the original performance and effectiveness of each type of cosmetic. For skin care cosmetics, changes in the texture such as the extensibility and stickiness, luster, cleansing ability, lathering, etc., are important; in powder-type makeup cosmetics, changes in the lasting quality, covering power, applied color, etc., are important, while in point makeup like nail enamels and lipsticks, changes in adhesion (peeling), luster, drying speed, lasting quality, coloring ability, water resistance, oil resistance, etc., are important. In hair cosmetics, changes in setting and waving ability, effect on hair luster, coloring, bleaching, hair removal ability, etc., are important. Such tests evaluate any changes in the above characteristics and the results are reflected in the formulations providing the best combination of components and the best concentration of functional ingredients. 8.1.3. Aerosol stability tests Aerosol cosmetics are composed of a concentrate and propellants. Although the stability of the concentrate can be tested using the methods described in Sections 8.1.1 and 8.1.2 above, it is also necessary to confirm the stability of the final product separately as well. As there have been many cases of problems related to the structure and materials of the valve and concentrate, it is very important to investigate the following items sufficiently to ensure the stability of aerosol products. (1) Mutual solubilities of the liquid or compressed gas and the concentrate. (2) Change in ejected state from aerosol container. (3) Change in internal pressure and flammability. (4) Blockage of nozzle by setting agents such as hair setting lotion. (5) Foaming condition with temperature change. (6) Degradation of nozzle by volatile ingredients in aerosol products. (7) Gas leaks when inverted or turned on side. The following outlines the methods for testing the corrosion, leakage and blockage of aerosol containers. (1) Corrosion test: observe whether or not there is any rust on the surface of the aerosol container after it has been left upright and inclined at room temperature and elevated temperatures over the long and short term.

Stability of cosmetics

(2)

(3)

195

Leakage test: fill the aerosol with a predetermined measured test weight and determine whether or not there are any changes in the weight after the container has been left upright, horizontal and inclined at room temperature and elevated temperatures for long- and short-term periods. Blockage test: operate the test valve for a fixed length of time at a fixed temperature (low and high), and observe the ejected state. Spray the aerosol for a number of seconds, doing this daily, every other day or every other month to determine whether or not the valve becomes blocked.

8.1.4. Special accelerated stability tests The stability of cosmetics must be guaranteed until the consumer stops using or has used all of the product. For this reason, a number of special accelerated test procedures matching each product have been developed to guarantee the characteristics of the cosmetics over an extended usage period. The evaluation does not just use one test but evaluates the product using a combination of various tests. This method of evaluating stability does not just evaluate the stability of the base formulae; as described below, it also evaluates the stability of the pharmaceutical agents. From the viewpoint of research efficiency, as well as quality assurance for the various functions and stability of the cosmetic various tests have been developed and are carried out. Some typical accelerated tests are described below. 8.1.4.1. Temperature and humidity combination tests Special accelerated testing is performed by combining various temperatures and humidities. For example: temperatures 37°-50°C; humidities: 75-98%. 8.1.4.2. Cyclical temperature tests These tests are not conducted at a fixed temperature and humidity; to simulate the yearly and daily changes in temperature, the test temperature is changed cyclically a number of times each day. Fig. 8.2 shows an example of such a test. 8.1.4.3. Stress test This test takes the overall stress and time period of actual usage into consideration; it predicts the stable life span of the product from the physical changes induced by stress over a fixed level. The physical changes monitored by this test include changes in separability and emulsion particles (coalescence, coagulation, irregular form and viscosity). Two cycles per day

High Temperature

0

6^

Low Temperature Fig. 8.2. Cyclical temperature test.

196 New cosmetic science

It is commonly applied to liquid emulsions such as shampoos, rinses, milky lotions, and lotions containing powder, as well as paste type products such as toothpastes, packs, gels, creams and mascaras. (1) Centrifugal separation method. In this test, the product in its container is subjected to a centrifugal force by spinning at a constant speed and the separation is measured. The results of the test are reflected in the formulation of cosmetics in comparison with the stability observed in the static condition. (2) Vibration test. This method is used to verify the effect of vibration during transport by truck and train, etc., on cosmetics. The vibration amplitude and duration of the vibration machine are determined by investigating the vibration encountered during distribution. (3) Drop test. This method is used for powdery type cosmetics such as powdery foundation, eye shadow, brusher and face powder. The product in its container is dropped repeatedly from a fixed height to investigate its ability to withstand shock. The number of drops before breakdown is investigated to fix a standard for passing products. This guarantees the product when it is accidentally dropped by the consumer and for the assumed conditions inside a handbag. (4) Load test. This test is used to examine stick-type products like lipsticks and pencils by forcible bending. The load in actual usage is measured, and the product is tested at a load exceeding this load to observe the level at which deformation occurs. Standardization of the load angle, and distance from the pressure point are very important items; the results are the cumulative number of measured times to deformation. (5) Friction test. This test is used to evaluate the durability of soaps and enamels. In the case of soap, the test analyzes the wearing dissolution by dipping the bottom of the soap into water and applying a fixed load. The changes in the amount before and after testing are measured to determine the wearing dissolution. In the case of nail enamel, the wear is analyzed by applying a fixed frictional load to the dried nail enamel film and the film endurance characteristics are evaluated. The above describes some accelerated test methods, but they can only predict the stability of the base formulae over the elapsed time in the laboratory, so to increase the prediction accuracy, it is important to improve the match by checking this against data from the actual usage environment.

8.2. Stability of pharmaceutical agents and test methods 8.2. L Quality assurance for pharmaceutical agents in cosmetics Some pharmaceutical agents are easily degraded by atmospheric oxygen and they are often chemically unstable compounds. For example, vitamins A, Bi, B2, Bg, C, etc. are all unstable. Moreover, there may be ingredients with which a particular compound is incompatible when it is mixed together with them in a cosmetic system and some may be easily affected by changes in pH. The stability of pharmaceutical agents in quasi drug products is established on the basis of accelerated tests of drugs defined by law in Japan. These tests are carried out for 6 months or more, at a temperature of 40°± 1°C and

Stability of cosmetics

197

75 ± 5% RH. The stability data obtained by these test conditions are considered equivalent to data collected over 3 years or more at room temperature. Generally, the regulated content range is 90-110% and the test data is obtained three times from three lots (nine times total). To guarantee the stability of pharmaceutical agents in the product under these types of controls, first, it is necessary to verify the stability data at the level of raw materials. Next, base formulae whose stability over time can be verified are selected, and finally, it is necessary to select a container that minimizes the effect of light, etc., on the contents. To ensure the stability of pharmaceutical agents used in the product, it is also very important to previously understand the effect of the other ingredients used, as well as the effects of pH, temperature, and incompatible compounds, etc. In order to stabilize an unstable pharmaceutical agent in a product, it is very important to decrease oxygen in the container, add anti-oxidants and chelating agents, adjust pH, choose the optimum amount of agent, eliminate impurities, and choose the optimum temperature during the production process, as for example, in low-temperature emulsification and post-addition of agents. In addition, it is also important to maintain stability at the raw material level (cool and dark storage). Moreover, when there is a possibility of absorption by the container, it is extremely important to select the right container and container materials at the design stage. 8.2.2. Stability tests for quasi drug products Basically, quasi drug products are subjected to the same kind of strict quality regulations as ethical drug products. Consequently, one quick method of predicting the stability over time is to measure the stability of a product that has already been aged at 50°C or higher temperatures. Moreover, records related to quality testing, etc., must be kept for at least 5 years after obtaining approval if requested, and it is best if inspection and quality control sections are established to control records from the sections with responsibility for formulating and analysis.

8.3. Stability of mass-produced cosmetics Although there may be no problems in product prototypes and stability evaluation at the R&D stage, it has been reported that sometimes at the mass production stage there is separation and the desired viscosity and color shade may not be achieved. It is extremely important to pay attention to the following items to assure quality when scaling up production from the development to mass-production stages. (1) Variation in raw material lots (2) Differences in manufacturing conditions (temperature, shear stress, production time, addition method and sequence) (3) Differences in filling conditions (excessive cooling, re-dissolution, shear stress due to machinery, continuity) (4) Production amount (example: 1 kg -> 1 ton -> 10 tons) Such variations in manufacturing conditions cause the product quality of cosmetics to

198

New cosmetic science

vary from the desired quality, and it is most important at the R&D stage to give full consideration to the quality control procedures such as testing the effect of the ingredients and manufacturing processes so as to prevent any problems occurring before full-scale production starts. In other words, stability is not maintained point-by-point but is achieved through a broad approach. In the manufacturing plant, sometimes problems cannot be solved instantly; perhaps the solution is in the process conditions or perhaps in the ingredient formulation and sometimes sudden scaling up to mass production is not possible. In this latter case, it may be necessary to proceed step-by-step to full-scale production via an intermediate pilot plant. Problems discovered in points 1-3 above must be understood and solved.

8.4. Assurance stability based on usage environment As mentioned early in this section, the stability of the cosmetic must match the anticipated usage requirements, so the product quality assurance (stability and safety) must take into consideration how the consumer actually uses the product. For example: (1) Soaps and cleansers: may become soggy or have reduced viscosity or usability due to immersion in water (2) Sunscreens: may stain sports clothes and swimming costumes and the stain may be hard to wash off (4) Bath preparations: may cause damage to the bathtub or may stain towels with plant extracts, etc., in them or may be accidentally ingested or enter the eyes (5) Aerosols: solvents in aerosols may have a harmful effect on household goods, or gases may leak out due to misuse and the contents may not come out. (6) Cosmetics containing strong solvents: may damage spectacles, combs, sponges, bathroom fittings, etc. (7) Hair coloring products: may stain hands, towels and bathroom fittings and accessories. Although some examples are explained above, when considering the stability of cosmetics, thorough consideration must also be given to the possible occurrence of phenomena which are not only physico-chemical in nature.

9

Preservation of cosmetics

9.1. Need for adding preservatives to cosmetics In addition to their principal ingredients of oil and water, cosmetics often also contain such substances as glycerin and sorbitol which provide a source of carbon for microorganisms, and such substances as amino acid derivatives and proteins which provide a source of nitrogen for them. So, as for foods which contain similar ingredients, it is easy for them to be contaminated by fungi, bacteria and other microorganisms. However, no real comparison can be made between cosmetics and foods in terms of the risk of deterioration due to microorganisms, because the usage period is much longer for the former, extending to several years in some cases. It is therefore necessary to add preservatives to cosmetics for their long-term protection against putrefaction and bad smells due to bacterial contamination from the fingers and other sources during use. Among the microorganisms in our daily lives, the ones that contaminate cosmetics and proliferate inside them are mainly bacteria; but cosmetics are also contaminated by fungi and yeasts. The general characteristics of typical microorganisms contaminating cosmetics are listed in Table 9.1.

Table 9.1. General characteristics of microorganisms which contaminate cosmetics Fungi Optimum growth temper20—30° ature

Bacteria

Yeasts 25—30°

25—37°

Preferred nutrients

Starch Plant-based foods

Sugars Plant-based foods

Proteins, amino acids Animal-based foods

Optimum growth pH

Acidic

Acidic

Weakly acidic-weakly alkaline

Aerobic/anaerobic

Aerobic

Aerobic-anaerobic

Usually aerobic, sometimes anaerobic

Major products

Acids

Alcohols, acids carbon dioxide

Amines, ammonia acids, carbon dioxide

Typical species

Penicillium Aspergillus Rhizopus

Saccharomyces Candida albicans

Bacillus subtilis Staphylococcus aureus Escherichia coli Pseudomonas aeruginosa

199

200 New cosmetic science

9.2. Primary and secondary contamination Article 56 of Japan's Pharmaceutical Affairs Law (Sale, Manufacturing and Other Prohibitions) prohibits "The sale, manufacturing, etc. of drug products contaminated with pathogenic microorganisms or with those having the risk of contamination". In exactly the same way, it is undesirable to manufacture or sell cosmetics which are contaminated by pathogenic microorganisms. But even if the microorganisms are not pathogenic, contamination by them is inappropriate, from the standpoints of both user and manufacturer, because it signifies that the manufacturing process is unhygienic, there will be deterioration in product quality as time goes on and skin irritation will result from this. Contamination by microorganisms arising during production is called primary contamination and that arising during the use of the product by the consumer secondary contamination. Primary contamination often arises from bacteria in water (gram negative rods) while secondary contamination often results from bacteria from the hands and usage environment (gram positive cocci and gram positive rods). To prevent primary contamination arising during manufacturing and filling, it is necessary to provide a clean working environment by installing such equipment as dust filters in the ventilation system and dehumidifiers, sterilizing water by heat and ultraviolet treatment, sterilizing raw materials by ethylene oxide gas and heat treatment, washing manufacturing equipment and sterilizing it using heat or chemical treatment and educating workers on cleanliness at work, in order to ensure that production is carried out under clean conditions overall. Primary contamination may be prevented by strictly observing good manufacturing practice (GMP)^) and now products are becoming unacceptable to the consumer if they are not made in factories conforming to GMP. Every country has its own standards for live bacteria counts in the final product. The guidelines'^ of America's Cosmetics, Toiletries and Fragrance Association (CTFA) state that the number of live bacteria in 1 g of product must be less than 500 for baby products and eye makeup cosmetics and less than 1,000 for other products; and that pathogenic bacteria are unacceptable. The Japan Cosmetic Industry Association's own guidelines state that the number of live bacteria in 1 g of product must not exceed 1,000 and that pathogenic bacteria are unacceptable. Testing for microorganisms in cosmetics and attitudes towards pathogenic bacteria are explained in detail in "Microorganism Testing for Drugs and Cosmetics"^^ Coagulase positive Staphylococcus aureus, Escherichia coli species and Pseudomonas aeruginosa are examples of the pathogenic bacteria which must not be detected in cosmetic products and it is the responsibility of the manufacturer to carry out GMP control on a daily basis so that such sources of primary contamination are not detected. However, although there are absolutely no standards or testing for resistance to secondary contamination, every cosmetics company now carries out individual testing on the basis of the procedures in the 19th Edition of the US Pharmacopoeia^) and CFTA procedures^). There are a tremendous number of microorganisms in our daily living environment; in the air there are 8-35 x lO^/m^, in soil 1 x 10^-5 x lO^^/g and on the human scalp 1.4 x lOVcm^^). There are also large numbers of bacteria on our hands and faces and cosmetics are contaminated by them when we put in our fingers to take some out, put some

Preservation of cosmetics 201

back after taking too much on the hand or leave the cosmetic with the lid off for some time. Preservatives are added to cosmetics to prevent this contamination which they do by suppressing the proliferation of microorganisms and killing them in time, thus preventing deterioration of the product. However, it is necessary to make efforts to add the smallest possible amount by taking into account such items as the period of use and number of applications the volume of the contents is sufficient for, as well as the number of chances of contamination that there are with a particular form of container.

9.3. Antimicrobial agents Antimicrobial agents come under two headings depending on the reason for using them. 9.3.1.

Preservatives

Preservatives are added to cosmetics to suppress the proliferation of microorganisms which have contaminated them and to kill them in time, thereby preventing deterioration of the product. Suppressing the proliferation of microorganisms is called microbiostasis and preservatives make use of this action to prevent product deterioration. Preservatives do not have such a strong effect by themselves; the ones in general use blend in well with the ingredients of the cosmetic and gradually kill off the contaminating microorganisms in time. Typical ones are paraoxybenzoates which are commonly known as parabens. Parabens are also much used in food products. 9.3.2. Disinfectants and germicides Disinfectants and germicides are added to cosmetics with the purpose of sterilizing the surface of the skin and keeping it in a clean condition. The requirements of disinfectants and germicides are that they kill germs or reduce their numbers in a short period of time. The disinfectants and germicides used in anti-acne products, deodorants and other cosmetic products suppress the proliferation of the germs on the skin thought to cause acne, thereby preventing its occurrence as well as its aggravation, and kill or reduce the numbers of bacteria in the armpit thought to be a cause of body odor. Disinfectants and germicides are also used in dandruff control products because they have the ability to suppress Pityrosporum ovale, a yeast suspected of causing it. However, many problems have to be solved when actually using them: for example they may react with the other ingredients in the cosmetic, may not readily dissolve in it or their effectiveness may be greatly reduced due to reaction with proteins on the skin. Typical examples are benzalkonium chloride, chlorhexidine gluconate and trichlorocarbanilide (TCC). Disinfectants and germicides are also used for sterilization in order to prevent primary contamination during the manufacturing process. As the largest source of contamination in the manufacturing process are gram negative bacteria, many of which are very resistant to disinfectants and germicides, benzalkonium chloride and chlorhexidine gluconate (both water-soluble) are made into alcohol solutions when used. They are also made into

202 New cosmetic science

acid or alkaline solutions when used for this purpose. In order to prevent mixing with the product, GMP stipulates that it is essential to wash off such agents completely after use for sterilization. 9.3.3. Characteristics required of antimicrobial

agents

Not all antimicrobial agents may be added to cosmetics as some have undesirable characteristics and some may be used as either a preservative or a disinfectant/germicide depending on the purpose of the product. Antimicrobial agents are used on the basis of having as many as possible of the ideal characteristics'^) in the following list. (1) Efficacy against many species of microorganisms (2) Water solubility or easy dissolution in commonly used cosmetic ingredients (3) High safety, no irritation (4) Neutral with no effect on product pH (5) No reduction of product ingredient effectiveness (6) No adverse effect on product appearance (discoloration, etc.) (7) Stability over wide temperature and pH range (8) Readily available and stable supply (9) Low in price and economical to use

9.4. Antimicrobial agents used in cosmetics In Europe, a list of preservatives permitted in cosmetics has been published under the title EU Cosmetic Directive^) in the EU Official Journal. In the United States, the Food and Drug Administration (FDA) has published a list of substances (Prohibited and Controlled Substances) prohibited for use in cosmetics in its Code of Federal Regulations^^ which also contains preservatives. Preservatives used in cosmetics in the United States are listed in the International Cosmetic Ingredient Dictionary^^^ published by the CFTA. Table 9.2 lists the antimicrobial agents stipulated in Japan's Comprehensive Licensing Standards of Cosmetics by Category^^\ These quality standards have been drawn up by the Ministry of Health and Welfare on the basis of the Pharmaceutical Affairs Law and suggestions of the Central Pharmaceutical Affairs Council, and indicate upper limits on safety. For each antimicrobial agent, it is necessary to check such items as the solubility, safety, effective pH range, prohibitions on use, smell, color and their actual effect in a cosmetic product when considering their inclusion in cosmetics. The use of some antimicrobial agents is limited to soaps, shampoos and other products which are rinsed off after use and the quantities of some may be increased when used in such products. Antimicrobial agents whose use is controlled in Japan due to safety concerns are listed in Table 9.3.

Preservation of cosmetics

203

Table 9.2. Antimicrobial agents stipulated in Japan's comprehensive licensing standards of cosmetics by category

Agents

Structural formula

^^COOH

Benzoic acid

Salicylic acid

Sorbic acid and sorbates

Paraoxybenz 0 a t e s ( p arabens) Parachlorometacreosol

0.2 (1.0) 0.1 (0.1)

CH^CH = CHCH = CHCOOH

Dehydroacetic acid and dehydroacetates

T^COCHs 0

HO-/~VcOOR

Effective in conditions

acidic

Pungent smell

0.5

Effective at pH 5 and below

0.5

Not readily affected by organic substances

1.0

Effective over wide pH range. Inactivated by non-ionic surfactants

HO 0.5

Cl-/~\-CH3 OH HO

CI

CI

Hexachlorophene

0.1 CI

Borax

acidic

0.2

Or°"

Carbolic acid

Effective in conditions 1.0

a"

Salicylates

Characteristics

0.2

Cr™"'

Benzoates

Stipulated maximum eoncentration{%)

CI

CI

Inactivated by non -ionic surfactants

CI

Na2B407 • I O H 2 O

0.76

HO Resorcin

Isopropylmethylphenol

Orthophenylphenol

P^'

CH3

HO-ZV-CH'^ ^ = /

\ H 3

0.1* (1.0)

Poor solubility

0.1

Peculiar smell

OH ^ _ , ^

CHa Benzalkonium chloride

0.1

^ O H

<^y-CH2-N-R CH3

+ ciR —Ci2"~'Ci4

0.05* (3.0)

Prohibited for use with certain materials, strong effect

204

New cosmetic science

Agents

Stipulated maximum concentration (%)

Structural formula

NH Cl-

NH

NHC-NHCNH(CH2)6NHCI NH

Chlorhexidine hydrochloride

Characteristics

NHCNH^f I

Vci

0.05 (0.1)

Poor solubility water

in

0.05 (0.1)

Strong effect in aqueous solution, cationic nature

0.05*

Cationic nature, readily decomposed

0.3* (0.5)

Effective against gram positive bacteria, poor solubility

0.1* (0.3)

Effective against gram positive bacteria, poor solubility

0.002

Soluble in glycols, sparingly soluble in water. Effective against Staphylococcus aureus and Escherichia coli

1.0

Soluble in water, alcohol and glycerin. Effectiveness range extended when used in combination with parabens

0.1

Insoluble in water ; soluble in alkaline solutions and organic solvents ; more effective against ordinary bacteria than fungi

2HC1

NH

NHCNHC. I ll\ NH NH^

ClChlorhexidine di-gluconate

I

(CH2)e

Cl-

2(CHOH)6

I

NHCNHC" I I NH NH

Alkylisoquinolium bromide

Trichlorocarbanilide

COOH

N^-R

CH2OH

BrR = C8~Cu

CI Cl-/~y-NHCONH - ^ ^ J ) - C l CF3

Halocarban

Photosensitizer 201

CI f ~ V - N H C O N H - /

H3C

-S S>-CH=< -Nv NV H . I

Phenoxyethanol

Trichlorohydroxydiphenylether (Triclosan)

V-Cl

, ^CH3

OCH2CH2OH

-Cl

ClCI

OH

*Excluding rinse-off products like soap and shampoo ( ) Rinse-off products The Comprehensive Licensing Standards of Cosmetics by Category (1994)

Preservation of cosmetics 205 Table 9.3. Restrictions on the use of antimicrobial agents in cosmetics Agent

Dates

Trichlorosalicylanilide (TCSA)

1960—62

Tribromosalicylanilide (TBS)

Problems

Nature of restriction No experience of use (Japan)

Photo-contact dermatitis (UK, US)

1962-

0.05% max.

Photo-contact dermatitis

Mercury compounds

9/6/62

Use prohibited (quasi-drug prodSkin ucts) (Notice) (excepting mercuric tion chloride)

Formalin

9/6/62

As above (Notice)

;;

Mercuric chloride

7/23/69

Use prohibited (ethical drugs*, quasi -drug products)

;;

Bithionol

4/4/70

Use prohibited (ethical drugs, etc.) (Notification)

Boric acid/borax

3/12/71

Self-restraint (quasi-drug products, etc.) (Notice) (The use of borax is Toxicity due to percutaneacceptable up to a maximum of 0. ous absorption 76% when its purpose is emulsifying beeswax)

Dichlorophen

1/12/72

Use prohibited (cosmetics) (Notification)

Photo-hypersensitivity

Hexachlorophene

3/2/72

Prohibited for use in bath preparations, talcum powders, and in deodorants (quasi-drug products) • • • a maximum of 0.4% (Notice)

Brain disorders at maximum dosage Toxicity due to percutaneous absorption

Halogenated salicylanilide (Tribromsalan ( T B S ) , Dibromsalan (DBS), Metabromsalan(MBS))

1/26/75

Use prohibited (ethical drugs, etc.) (Notice)

Photo-hypersensitivity

Hydrogen peroxide

4/1/83

Use prohibited

Mutagenicity

disorders,

sensitiza-

Photo-hypersensitivity

Excluding those taken under the supervision of a doctor (The Soc. Cosmet. Chem. Japan ed., Saishin Keshohin Kagaku (Japanese)), Yakujinippo, Tokyo, 1988)^^'

9.5. Methods for evaluating the effectiveness of preservatives As there are currently no standards or procedures in the regulations for testing the effectiveness of preservatives included in cosmetics to prevent secondary contamination, in Japan each cosmetics company carries out such testing individually on the basis of the US Pharmacopoeia. A detailed description of the procedures is given in Cosmetic and Drug Preservation Principles and Practice^^) and the recently published Antibacterial & Antifungal Handbooks^) edited by the Japan Antibacterial and Antifungal Society.

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New cosmetic science

As cosmetics are mixtures of so many different types of raw material, the preservatives in them are often inactivated. Some of the causes of this are large or small oil polarity, total oil amount^^\ HLB and total amount of non-ionic surfactants^^\ polymer compounds such as thickening agents, film formers and humectants^^'^^^' as well as the plastic^^^ and rubber of containers. It is therefore difficult to predict the effect of a preservative, in view of the ingredients in the cosmetic formula, as well as estimate the amount required; so each product must be tested individually by inoculating it with microorganisms to see if they are killed or not. Thus, if the individual factors affecting the action of a preservative are analyzed and the cosmetic is made to consist of ingredients having little inactivating effect, such as oils with low polarity and surfactants with low HLBs, it is possible to reduce the preservative requirement. On the other hand, if the cosmetic consists of large amounts of ingredients with a strong inactivating effect^^^ such as high polarity oils, high HLB surfactants and polyethylene glycol, it has been shown that the amount of preservative must be increased, as we would expect. Further, among the dihydric glycols used as humectants, such as 1,3-butylene glycol, there are some which have a microbiostasis action against bacteria so if this can be used effectively in combination with the action of preservatives, the amount of preservative may be reduced. The "challenge test" and the "inoculum test" are used to determine if a product will kill microorganisms when it is inoculated with them; their basic details are listed in USP and CFTA guidelines. In these tests, the product is inoculated with Eumycetes (fungi and yeasts), so that there are 1 x 10^ organisms/g in it, or bacteria at a rate of 1 x 10^/g and the result is observed over a period of 1-28 days. Although strains of designated standard microorganisms are used for the tests, in many cases the manufacturer may use also use his own strains taken from products which have been returned by consumers due to contamination. Though it is not possible for such strains to be truly representative of all the microorganisms in our environment, we can assume that products tested by current methods assure a certain degree of quality in cosmetics on the market because they are not being spoiled by microbial contamination. An important task for the future will be to upgrade quality assurance by paying great attention to complaints about products due to contamination. For further details on preservation techniques used in cosmetics and ethical drugs, we refer the reader to Cosmetic and Drug Preservation^^^ which contains much useful information on the principles and practices of the current major preservation techniques and the different types of preservative in use.

9.6. GMP and its validation In 1969, the World Health Organization (WHO) drew up "Good Practices in Manufacture and Quality of Drugs" with the object of ensuring the availability of high quality drugs in order to prevent the serious illness and death caused by inferior quality drugs in the past; and urged member countries to implement them. The purpose of this standard, which is commonly known as GMP^\ is to guarantee that products have adequate quality

Preservation of cosmetics

207

when they reach the market and it covers all aspects from the receipt and storage of raw materials through each stage of the manufacturing process right up to the shipping of the finished product. The prevention of microbial contamination occupies a very important position within GMP. In order to prevent primary contamination, the product should be made in a sanitary environment using hygienic practices and sterilized materials and the containers thoroughly washed or sterilized before filling. Some of the actual means of providing a sanitary manufacturing environment are as follows. (1) Use of filters to remove dust from the ventilation air: each gram of dust may contain anything from one to a million microbes. It is particularly important to remove the large numbers of bacteria and fungi spores because of their great heat resistance. (2) Dehumidify air through air-conditioning: it is essential to dehumidify the air because of the large numbers of Escherichia coli and other gram negative bacteria present in moist air. (3) Provide ultra-clean environment through the use of microbe filters: use HEPA filters to provide a very high degree of cleanliness (near microbe-free environment). (4) Install double doors or positive pressure system to prevent untreated air from the outside coming in. Methods used for ensuring that raw materials are sterile include the following: (1) Water sterilization by means of filters to remove microorganisms (0.22 //m), heat sterilization, ultraviolet sterilization (2) Heat or ethylene oxide sterilization of raw materials (3) Ethylene oxide sterilization of plastic containers It is also necessary to give instruction on clean working practices emphasizing the following: (1) The tremendous numbers of bacteria on the fingers and how to remove them (2) Theory and practice of sterilization methods (drying, UV, chemicals, heat) and points for attention (3) Ways of removing dust and microorganisms from work clothes, shoes, etc. In order to enhance the precision with which GMP is implemented, the new concept of "validation"2i) has been introduced. Validation means that it is not just enough to implement GMP; "the processes and procedures implemented must be designed so that they are appropriate and have a scientific basis and are systematically inspected to see whether they achieve the desired objectives or not". For example, the sterilization of water goes further than simply using heat or UV to kill microbes in it; it also involves constant checks to ensure that the water reaches the required temperature and is maintained at it for the required period of time, that UV lamp output is maintained at the required level and that the irradiation is done for the required period for sterilization, as well as carrying out culture tests at fixed periods to confirm that the water is sterile. Validation also entails keeping records of the results and tracing the cause of problems that occur so that the sterilization conditions may be changed if necessary. GMP and GMP validation are not limited to drugs; they are also a fundamental concept in the quality control of cosmetics and have been helping to raise the quality of cosmetics in Japan since around 199022>.

208

New cosmetic science

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22.

Sharp, J.: Good Manufacturing Practice: Philosophy and Apphcations, Interpharm Press, 1991. CTFA: Cosmetic J., 4 (3), 25 (1972). Kurata, H., Ishizeki, T. et al\ Microorganism Testing for Drugs and Cosmetics, p. 35, Kodansha, 1978. US Pharmacopoeia XIX USP Convention, Inc. p. 587, 1975. CTFA Technical Guideline, 1975. Henry, S.M.: TGA Cosmetic J., 1 (3), 6 (1969). Gershenfeld, L.: Am. Perfum. Cosmet., 78, 55 (1963). Cosmetic Directive 76/768/EEC Annex VI. Food and Drug Administration: Title 21, Code of Federal Regulations part 700. CTFA: International Cosmetic Ingredient Dictionary 6th edition, 1995. The Comprehensive Licensing Standards of Cosmetics by Category, Yakuji Nippo Ltd., 1994. Keshohin, Kagaku, Kenkyukai Ed., Saishin Keshohin Kagaku (Japanese) J. Soc. Cosmet. Chem. Jpn., Yakuji Nippo Ltd., 1988. Kabara, J. J.: Cosmetic and Drug Preservation: Principles and Practice, Marcel Dekker, New York, 1984. Antibacterial & Antifungal Society of Japan: Antibacterial & Antifungal Handbook, p. 843, Gihodoh, 1986. Bean, H. S.: J. Soc. Cosmet. Chemists 23, 703 (1972). deNavarre, M. G.: J. Soc. Cosmet. Chemists 8, 68 (1957). Patel, N. K. et al\ J. Pharm. Sci. 53, 94 (1964). Bean, H. S. et al\ J. Pharm. Pharmacol. 23, 699 (1971). Macarthy, T. J. et al: Cosmet. Perfum. 88 (5), 43 (1973). Yamaguchi, J. et al: J. Soc. Cosmet. Chemists 33, 297 (1982). FDA: Guideline on General Principles of Process Validation (May 1987). Asaka, Y.: J. Antibacterial Antifungal Agents, Japan 19 (6), 319 (1991).

10 Safety of cosmetics Cosmetics are products used externally to keep the skin clean and healthy. In general, cosmetics are used repeatedly on the skin of healthy people over the long term, and ethical drugs are used to help recovery from illness over a limited period. Thus, cosmetics must be absolutely safe in use in contrast to ethical drugs, the usage benefits of which must be weighed against the risk of side effects. In other words, cosmetics are used by large numbers of people, and the usage basically depends on the users. From this point of view, it is essential that every possibility is taken into consideration to ensure safety. This chapter describes a practical concept of the safety of cosmetics and the basic approaches for ensuring their safety.

10.1. Basic concept of cosmetic safety Cosmetics are composed of various ingredients. Many acceptable components for general use are well documented^-^^ However, useful new compounds, not listed in the references, have been developed as a result of technological progress. The concept of reasonably estimated as safe (REAS); substances reasonably estimated as safe, was accepted for ingredients that have been used for a long time, similar to generally recognized as safe (GRAS), substances generally recognized by experts as safe, for food additives. However, concerns about safety or health problems are changing with the era. Therefore, it has become necessary to reconsider the scientific evaluation of cosmetic ingredients'^'^) as reported in the Cosmetic Ingredient Review^) (CIR) established in 1976 by the Cosmetic, Toiletry and Fragrance Association (CTFA) of the USA. Also, the fragrance components of cosmetics are evaluated for safety by the Research Institute for Fragrance Materials (RIFM) established in 1966, and the research results are disseminated through the scientific journal. Food and Chemical Toxicology (formerly Food and Cosmetic Toxicology). In Japan, the Ministry of Health and Welfare (MHW) presented guidelines entitled "Safety Data Required for Application of Imported Cosmetics and for Manufacturing Cosmetics Containing New Materials" in 1987 to guarantee the safety of new materialsio) (Table 10.1). The need for safety testing is based on the concept that cosmetics are beneficial to human skin only if their safety is confirmed in proper usage. Therefore, the basic strategy for safety assessment of cosmetics is the same as for medical drugs or other chemical substances^'^^\

209

210

New cosmetic science Table 10.1. Safety data required for application of cosmetics containing new raw materials

1. 2. 3. 4. 5. 6. 7. 8. 9.

Test Item

Ingredients

Products

Acute toxicity Primary skin irritation Cumulative skin irritation Sensitization Phototoxicity Photosensitization Eye irritation Mutagenicity Human patcli test

Required Required Required Required Required*"^ Required'^^ Required Required Required

Case by case^^ Not required Not required Not required Not required Not required Required"*^ Not required Required^^

Notes: a) Execute test when LD 50 of target new material is 2 g/kg or less. However, the test is not required when the product is assumed to be safe in consideration of the amounts formulated, b), c ) Not required for material with no UV absorption. d) Not required when irritation responses of cornea and iris are not observed and also chance of exposure to eyes is low. e) Not required for products that are rinsed off. When it is necessary to take great care about toxicity of new materials including bactericides, preservatives, antioxidants, chelating agents, UV absorbents and coal-tar dyes, it may be necessary to add data about subacute toxicity testing, chronic toxicity testing, reproductive toxicity testing, absorption, distribution, metabolism and excretion testing, etc.

10.2. Safety test items and evaluation method The basic concept of the guidelines described above is based on the fact that cosmetics are used for long periods on the skin; it is necessary to confirm that cosmetics do not cause any irritations and toxic responses soon after use, as well as irritation, toxic and allergic responses due to repeated use in the long term. Although it is necessary to confirm the final safety using human volunteers, in many cases various animal models are used as screening tests. 10.2.1. Skin irritation In confirming the safety of cosmetics, the first important point is that cosmetics must not cause any contact dermatitis (rash) when applied to the skin. The cause of contact dermatitis is not always due to cosmetic ingredients. Even if the safety of cosmetics is verified, it is known that environmental conditions such as temperature and humidity when the cosmetic is used, misuse by the consumer, and the user's constitution and physical condition may all cause contact dermatitis (Table 10.2). This section describes the typical methods for guaranteeing the safety of cosmetics to prevent contact dermatitis. Skin irritation is caused by the direct toxicity of chemicals on cells or blood vessels in the skin and is different from contact allergy caused by the immune response described

Safety of cosmetics

211

Table 10.2. Factors influencing skin response 1) Materials 1. Physico-chemical property 2. Purity 3. Solvent (diluent) 4. Concentration 2) Biological factors 1. Genetic factor (species and strains) 2. Sex 3. Age 4. Skin condition 5. Individual variation 3) Environmental conditions 1. Season 2. Temperature and humidity 4) Application and usage 1. Frequency 2. Treatment conditions 3. Period of application and use

later. This type of response is observed in many people when exposed to strong acids or alkalis. Rabbits and guinea pigs have long been used as test animals due to their similar response to that of humans and their high responsiveness. The Draize primary skin irritation test^^'^^'^^) outlined below is often conducted on rabbits. (1) Six or eight rabbits are used. (2) The rabbit's back is clipped free of hair, and the rabbit is held in an animal holder. (3) The test material is applied to two areas on the back. One area is scratched with a sharp instrument such as a hypodermic needle (abraded skin) before the application, and the other area is used untouched (intact skin). (4) The test material (0.5 g or 0.5 ml) is applied to the test area using a 2.5 x 2.5 cm^ patch test plaster. (5) The test material is kept in position for 24 h. (6) After 24 h, the test material is removed and the skin response is evaluated as redness (erythema) and swelling (edema), etc. (7) The skin is re-evaluated after 72 h. The average response index is calculated and the degree of skin irritation is evaluated. Guinea pigs are also used for skin irritation tests since they are easily handled. In the case of guinea pigs, the back or the flank is clipped free of hair, and the test material is applied once or repeatedly to the skin without a patch test plaster. 10,2.2, Sensitization

(allergenicity)

The allergic response may occur when the body is repeatedly exposed to the chemicals with sensitizing potential. If the chemicals are administered via the skin, it is called contact sensitization (contact allergenicity). The sensitization response differs from irritation, which is a local reaction. Since the elicitation is mediated by T-lymphocytes derived from the thymus, contact sensitization is categorized as a cellular immunity compared to humoral immunity such as asthma or anaphylactic shock caused by antibodies. Contact sensitization is also classified as a delayed-type hypersensitivity because the inflammatory reaction is often delayed. The sensitization test is an important test item in evaluating the safety of cosmetics used over the long term. At the immunology research stage, the mouse is often used as the test animal, but the guinea pig is generally used to test cosmetics and their ingredients. The maximization test^^'^^) is commonly used due to its high sensitivity. The procedure is divided into two

212

New cosmetic science

Stages: induction and challenge. In the induction stage, first, emulsified Freund's complete adjuvant (FCA; a mixture of heat-treated tuberculosis bacteria, liquid paraffin and a surfactant) is injected intradermally into the shaved dorsal skin followed by the test material, and an emulsion of the test material and the same amount of FCA. One week later, the test material is occlusively applied percutaneously after treatment with sodium lauryl sulfate in order to boost the sensitization. In the challenge stage 2 weeks later, the test material is applied to the shaved back of the test animal and the sensitization is evaluated based on the skin response 24 and 48 h later. Although the maximization test has high sensitivity, it is occasionally criticized because it is sometimes not easy to emulsify the test material with FCA, especially final products, and intradermal injection may not represent the risk of real use. In this case, the adjuvant and patch test method^^\ which retains high sensitivity, can be used to evaluate the final products using percutaneous application of the test material. Also, other non-FCA methods, such as Buehler's method^^^ and the open epicutaneous test^^'^^^ are useful. Some of the impurities in coloring agents, preservatives and fragrance material have been reported as allergenic materials and it is extremely important to perform sufficient testing at the developmental stage on compounds expected to have special biological effects. 10.2.3.

Phototoxicity

Some chemicals cause a skin irritation response only in the presence of light. These types of materials are called phototoxic materials. A typical example is bergapten (5-methoxysoralen) found in bergamot oil, a fragrance material, which causes Berlock dermatitis. When the fragrances containing these types of compound are applied and then exposed to sunlight, erythema is observed at some parts and, moreover, brown pigmentation may be observed. In screening these types of materials, it is best to use sunlight as the light source, but in actuality, sunlight varies greatly in energy and wavelength distributions depending on the season and time of day. Consequently, phototoxicity testing often uses a xenon arc lamp or a commercial black lamp. Since the wavelength band causing the inflammation response varies with the material, it is important to select the appropriate light source. Generally, materials that have an absorption band in the UV region are tested. Therefore, long-wavelength UV light (UVA) or mid-wavelength UV light (UVB) at a non-erythema dose rate is generally used. Both guinea pigs and rabbits are used as test animals^^'^^^ The test material is applied to the clipped back skin of the animal and the phototoxicity is evaluated as the difference between the response of the part with light exposure and that without light exposure. 10.2.4. Photosensitization

(photoallergenicity)

Photosensitization is an allergic response observed only in the presence of light. Photoallergenicity has been reported for a number of types of materials including UV absorbents, bactericides, and fragrances. It is most important to verify that neither cosmetic products nor their ingredients are photoallergenic since cosmetic products on skin are

Safety of cosmetics 213

commonly exposed to sunlight in daily life. In particular, it is essential to evaluate the photoallergenicity of sunscreen products and UV absorbents which are usually used in the presence of strong UV light. Although the response mechanism of photosensitization is not clearly understood, it is believed that the process involves: (1) activation of the material by light, (2) changes in the cellular functions of the immune system, and (3) changes in the interaction between the material and cells of the immune system, etc. Mice and guinea pigs are often used as test animals^^'^^'^^-^^^ In either case, as in contact sensitivity testing, the procedure involves two stages: a photosensitization induction stage in which the chemical-treated skin is exposed to light, and a photosensitization challenge stage involving application of the test chemical and exposure to light after a certain period from the induction. The skin reaction of the light exposed and unexposed areas in the photosensitization challenge stage is monitored, and the photosensitization is evaluated as the difference in the response degree between the two areas. The results are compared with that of phototoxicity testing to confirm that the skin reaction is not due to photoirritation. 10.2.5. Eye irritation Cosmetics, especially those used on the face and around the eyes such as eye-shadows or mascaras, and hair-care products like shampoos, etc., may enter the eyes during use. Consequently, it is essential to confirm their safety with respect to eye irritation potential. The Draize method^^^ has long been used for this purpose. The test material is applied to one eye of a test rabbit and the response of cornea, iris and conjunctiva is observed over a certain time. In the original method, the response at 2 and 4 s exposure is also evaluated after washing out the test substance with water. It is important to thoroughly consider the risk assessment especially for products that may cause a strong response, such as shampoos containing surfactants with high cleansing power, products containing large amounts of organic solvents such as some hair styling preparations, and oxidation hair dyes. However, the eye irritation caused by many cosmetics such as regular creams, milky lotions and foundations is usually very low. 10.2.6.

Toxicity

10.2.6.1. Acute toxicity This type of testing is necessary to investigate the dangers of accidental ingestion of cosmetics by children and the systemic toxicity, as well as the kind of action to take should this happen. In this case, an oral toxicity test is carried out assuming the actual situation. The test substance is administered to a rodent such as a mouse or a rat using a stomach tube and the degree of toxicity is evaluated from the lethal dose, pathological investigation and general clinical observation. Formerly, the dose causing a 50% death rate in the animals (LD50; LD = lethal dose)^^) was calculated. Recently, from the view point of animal welfare, only a small number of animals are used and an approximate death rate is calculated^'^'^^. Test materials are administered orally, transdermally, subcutaneously and peritoneally for evaluation of the systemic toxicity as a single dose. Aerosols and powders are also

214 New cosmetic science

administered by inhalation, and the systemic acute toxicity is evaluated focusing on the respiratory system. 10.2.6.2. Subacute and chronic toxicity This type of testing is used to investigate the systemic effects, including the effects on the organs, of long-term and continuous use of cosmetics on the skin. Typical test animals are rodents and rabbits. Subacute and chronic toxicity are evaluated over 4 weeks to 3 months, and 6 months to 2 years test periods of, respectively. Generally, various parameters such as changes in feed intake, body weight and growth are monitored and blood chemistry and biochemical testing are carried out during the test. At the end of the test period, each organ is weighed and examined histopathologically, and the effect on the whole body including the special effect on specific organs is determined. 10.2.7.

Mutagenicity

This type of testing is used to investigate materials inducing mutations. Such materials may conceivably affect the incidence of inheritable diseases in man. It has been confirmed that many materials that cause cancer have mutagenic activity and many of the mutagenicity tests investigate materials for both mutagenic and carcinogenic activity. The relevant recommendations from the later review of the OECD guidelines (OECD 1994) and the 1993 International Workshop on Standardization of Genotoxicity Test Procedures (Mutation Research No 312(3) 1994) were taken into account in drawing up guidelines. 10.2.7.1. Reverse mutation test in bacteria^^^ Salmonella typhimurium, and Escherichia coli are often used as the test bacteria for the reverse mutation test. The test involves calculating the number of revertant colonies induced by the test material. 10.2.7.2. Chromosomal aberration test with mammalian cells in culture^'^^ Primary or established cell lines such as V79 Chinese hamster cells and Chinese hamster lung fibroblasts cells are usually used. The evaluation is performed by counting the number of cells in which structural chromosomal aberration or polyploid appear. 10.2.7.3. Micronucleus test with rodents^^"^ Mice are normally used in the micronucleus test. The test material is evaluated from the number of micronuclei in the polychromatic erythrocytes of the bone marrow from tested animals. The tests in Sections 10.2.7.1 and 10.2.7.2 are also performed under the influence of metabolic activity in vivo, which may cause the chemicals to be mutagenic. 10.2.8. Reproductive toxicity^^^ This type of testing is used to evaluate whether or not the chemicals have toxic effects on reproduction, for example on the in utero fetus, to examine the dangers of the test material to the reproductive process. In animal experiments, the period from preconcep-

Safety of cosmetics

215

tion to the end of lactation is divided into three parts, and the test is carried out for each period. Test materials are administered (1) prior to and in the early stages of pregnancy, (2) during the period of organogenesis and (3) during the perinatal and lactation periods. In most cases, rodents and rabbits are used as test animals. However, cosmetic materials are not commonly subjected to this test. 10.2.9. Absorption, distribution^ metabolism, excretion^^^ Cosmetics and their ingredients are defined as materials that have only a mild action on the human body. Nevertheless, it is important to know the possible effect of cosmetic ingredients on the body after percutaneous absorption in order to understand the mechanisms of irritation or toxicity as well as to obtain information regarding evaluation and prediction of safety of ingredients. The distribution in each organ of the body is examined using radiolabeled compounds on test animals. Also, the concentrations in the blood and urine are measured, and the metabolites are analyzed. In order to test the percutaneous absorption by a simple method, a small sheet of skin excised from a test animal mounted on a diffusion cell is generally used. 10.2.10. Testing on humans (patch test, usage testp^^ Clearly-discernible responses such as rashes, erythema, edema, pimples as well as invisible irritation responses such as itching, burning and stinging have been reported as a result of application of cosmetics. The visible response can be predicted to some degree from the results of safety tests previously described. However, before the product is launched on the market, it is very important to confirm its safety under the conditions of expected normal use and of reasonably foreseeable exaggerated use which might have been missed in the previous evaluation. In particular, it is very difficult to predict the risk of sensory responses such as burning, stinging and itching by using animal tests. Thus, a patch test and a stinging test on human volunteers with high sensitivity and a use test under normal conditions are required. However, such tests must be conducted in an ethical manner. 10.2.10.1. Patch tests To verify that a newly-developed material or products containing the material do not cause skin inflammation, a prophetic patch test is performed on the forearm or back of subjects. This patch test is different from that used by a dermatologist to diagnose the causes of dermatitis. The patch test is generally occlusive with plaster made for special use, but highly-volatile materials are applied in the open manner. The materials are usually applied for 24 h, and the skin reaction is evaluated by eye. 10.2.10.2. Controlled-use tests It is impossible to simulate all the conditions under which people use cosmetics by performing various animal and alternative tests. Thus, controlled-use tests are carried out to evaluate the safety of cosmetics in development when they are used under the recommended conditions. For example, environmental conditions such as temperature, humid-

216

New cosmetic science

ity and UV light, as well as the effect of perspiration are important for sunscreen products. For skin-care products, the skin reaction is observed in relation to skin conditions such as dryness and the amount of skin surface lipids. 10.2.10.3. Other tests The possible occurrence of contact sensitivity and acne are also investigated using the skin on volunteers' arms and backs.

10.3. Animal test alternatives A variety of animals and test methods are used in testing the safety of cosmetics for humans but, in recent years, such testing has become the focus of some criticism. To allay this criticism, efforts should be made to observe what are known as the three Rs: "replacement", the testing without animals should be actively developed and should be applied to an actual safety evaluation in order to meet the demands of society; "reduction", using as few animal's as possible and shortening testing times when animal testing must be carried out; and "refinement", improving tests to minimize the animal's pain and get the maximum information. Ideally, alternative test methods should be based on a reaction mechanisms and should be scientifically sound. A number of countries started making efforts to develop alternatives to animal testing relatively early. The Foundation for the Replacement of Animals in Medical Experiments (FRAME) was established in the UK in 1973 with this purpose in mind and in the USA, financial support from the cosmetics industry was used to organize courses on the subject and set up Center for Alternatives to Animal Testing (CAAT) at Johns Hopkins University in 1981. In Japan, the Japanese Society of Alternatives to Animal Experiments was set up in 1989. Cosmetics companies provide support for the research carried out by such organizations and have developed their own alternative testing methods. These methods are already in use for screening^^'^^^ At present, validation, which is carried out to confirm whether previously reported in vitro testing methods can be applied to practical use, is gaining ground. In Europe, The European Center for the Validation of Alternative Methods (ECVAM) was established in 1991 and has been carrying out validation particularly for alternatives to animal-based eye irritation and phototoxicity testing^^^s). Validation is also conducted by the European Cosmetic Toiletry and Perfumery Association (COLIPA) and the Cosmetic, Toiletry and Fragrance Association (CTFA) in the US. In Japan, the MHW project team organized in 1991 to look into the feasibility of using alternatives to eye irritation testing using animals is currently conducting a validation^^). The Japanese Society of Alternatives to Animal Experiments also conducts a validations^). Further, the Japan Cosmetic Industry Association (JCIA) is giving its full support to the MHW project and some of the cosmetic companies in JCIA individually provide assistance to the Japanese Society of Alternatives to Animal Experiments in the validation project. Animal test alternatives should see further development in the future as a new way of evaluating safety.

Safety of cosmetics 217

References 1. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Japanese Ministry of Health and Welfare: Supervision: The Japanese Standards of Cosmetic Ingredients, 2nd edn. Yakuji Nippo Ltd., 1985. 2. Society of Japanese Pharmacopeia: Supplement I—The Japanese Standards of Cosmetic Ingredients, 2nd edn., Yakuji Nippo Ltd., 1986. 3. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Japanese Ministry of Health and Welfare: Supervision: Supplement II. The Japanese Standards of Cosmetic Ingredients, 2nd edn., Yakuji Nippo Ltd., 1992. 4. Wenninger, J. A.: International Cosmetic Ingredient Dictionary 6th edn., Cosmetic, Toiletry and Fragrance Association 1995. 5. Wenninger, J. A. ed.: International Cosmetic Ingredient Handbook, 3rd edn., Cosmetic, Toiletry and Fragrance Association, 1995. 6. Council Directive 76/768/EEC of 27 July 1967, On the Approximation of the Law of the Member States relating to Cosmetic Products by the Council of the European Communities. 7. Van Den Heuvel, M. J., Clark, D. G., Fielder, R. T. et al.\ The International Validation of a fixed-dose Procedure as an Alternative to the classical LD50 test. Food Chem. Toxicol., 28, 469 (1990). 8. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Japanese Ministry of Health and Welfare: Supervision: Japanese Guidehnes for Nonclinical Studies of Drugs Manual, 1995. 9. C I R Cosmetic Ingredient Review 1993 Annual Report, 1993. 10. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Japanese Ministry of Health and Welfare: Supervision: The Comprehensive Licensing Standards of Cosmetics by Category, Yakuji Nippo Ltd., 1994. 11. Draize, J. H.: The Appraisal of Chemicals in Foods, Drugs and Cosmetics, Association of Food and Drug Officials of the United States, 1959. 12. Federal Register: Method of Testing Primary Irritation Substances, 38 (187), 1500, 41, September 27 (1973). 13. Federal Register: Primary Dermal Irritation Study, 43 (163) 81-5, August 22 (1978). 14. Magnusson, B., Kligman, A. M.: J. Invest. Dermatol., 52, 268-276 (1969). 15. Magnusson, B., Kligman, A. M.: Allergic Contact Dermatitis in the Guinea Pig; Identification of Contact Allergens, C.C. Thomas, Springfield, Illinois, 1970. 16. Sato, Y., Katsumura, Y., Ichikawa, H., Kobayashi, T., Kozuka, T., et ai: Contact Dermatitis, 7, 225-237 (1981). 17. Buehler, E. V.: Arch. Dermatol., 91, 171-175 (1965). 18. Klecak, G., Geleick, H., Frey, J. R.: J. Soc. Cosmet. Chem., 28, 53-64 (1977). 19. Maurer, T.: Contact and Photocontact Allergens; A Manual of Predictive Test Methods, Marcel Dekker, 1983. 20. Fitzpatrick, T. B., et al. eds.: Sunlight and Man, pp. 529-557, University of Tokyo Press, 1974. 21. Stott, C. W., Stasse, J., Bonomo, R. Campbell, A. H.: J. Invest. Dermatol., 55, 335-338 (1970). 22. Vinson, L. J., Borselli, V. F.: J. Soc. Cosmet. Chem., 17, 123-130 (1966). 23. Haber, L. C , Targovnik, S. E., Baer, R. L.: Arch. Dermatol., 96, 646-653 (1967). 24. Ichikawa, H., Armstrong, R. B. Haber, L. C : J. Invest. Dermatol., 75, 498-501 (1981). 25. Jordan, W. P.: Contact Dermatitis, 8, 109-116 (1982). 26. Council Directive 79/S31/EEC, Amending for the sixth time Council Directive 67/548/EEC on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labeling of dangerous substances, Official J. European Comm., No. L196, p. 1, 1967. 27. Annex to Commission Directive 92/69/EEC, 31 July 1992, Adapting to technical progress for the seventeenth time Council Directive 67/548/EEC on the Approximation of Laws, Regulations and Administrative Provisions relating to the Classification, Packaging and Labeling of Dangerous Substances, Official J. European Comm. No. L383A, Vol. 35, p. 1,1992. 28. Commission Directive 87/302/EEC, 18 November 1987, Adapting to technical progress for the ninth time Council Directive 67/548/EEC on the Approximation of Laws, Regulations and Administrative Provisions relating to the Classification, Packaging and Labehng of Dangerous Substances, Official J. European Comm., No. LI33, Vol. 31, p. 1, 1988. 29. Goldberg, A. ed.: Alternative Methods in Toxicology, Vol. 1, Mary Ann Liebert, 1983. 30. Loprieno, N., Alternative Methodologies for the Safety Evaluation of Chemicals in the Cosmetic Industry, CRC Press, 1995. 31. Hatao, M., Itagaki, H., Kobayashi, T and Ozawa, T.: Environ. Dermatol, 3, suppl.l, 103-118 (1996). 32. Balls, M., Botham, P.A., Bruner, L.H., Spielmann, H.: In vitro Toxicol., 9, 871-929 (1995). 33. Spielmann, H., Lovell, W.W., Holzle, E., Johnson, B.E. et ai: ATLA, 22, 314-348 (1994). 34. Ohno, Y., Kaneko, T., Kobayashi, T., Inoue, T., Kuroiwa, Y., Yoshida, T. et ai: In Vitro Toxicol., 7, 89-94 (1994). 35. Ohno, T., Itagaki, H., Tanaka, N., and Ohno, H.: In vitro Toxicol., 9, 571-576 (1995).

11 Usefulness of cosmetics

11.1. Usefulness of cosmetics Concerning the four important quality characteristics of cosmetics (safety, stability, usability and usefulness) as described in Outline of Cosmetics, viewing the changes in the characteristics of cosmetics, since the beginning of the 1980s, both safety and usefulness have come to be seen as important and with the development of new raw materials and pharmaceutical agents using life science based biotechnology techniques, new materials from fine chemicals and that of new preparations incorporating them, functional cosmetics with a high degree of usefulness are now being developed. Cosmetics and toiletries have now become such an integral part of our daily lives that we cannot imagine a life without them. Looking at the usefulness of cosmetics in accordance with the parts of the body they are used on (Table 11.1), we can appreciate just how many different kinds of cosmetics are of use to us in our daily lives. For this reason, we must be constantly thinking about usefulness in doing research on cosmetics, in manufacturing and marketing them. This chapter describes the research being done on usefulness giving examples. For details of the usefulness (roles) of products not described here, refer to the relevant chapters in Individual Cosmetics.

11.2. Research on usefulness of cosmetics Research on the usefulness of cosmetics comprises three areas: physiological usefulness, physicochemical usefulness and psychological usefulness. 11.2.1. Physiological

usefulness

Research on physiological usefulness involves that on alleviating skin roughness, preventing hair loss and other physiological aspects of the skin and hair. The core of such research is based on dermatology, physiology, biochemistry, pharmacology, molecular biology, immunology and other life sciences. As our society is rapidly aging, this is one of the most important areas of research.

218

Usefulness of cosmetics

219

Table 11.1. Usefulness of cosmetics

1. Hair

2. Face

Preventing balding

Hair growth promoter

Coloring hair (to look younger, smarter or more fashionable)

Hair color

Preventing hair condition

Hair treatment (split hair coating lotion, etc.)

damage, improving

4. Whole body

hair

Cleansing (physiological, sanitary)

Shampoo, Rinse

Hair styling

Hair styling lotion

Cleansing (physiological, sanitary)

Face cleansers

Preventing skin roughness, improving skin condition

Creams, Milky lotions, etc.

Alleviating liver spots

Whitening cosmetics

Alleviating wrinkles

Face treatment

Beautifying (color effect)

3. Body

Cosmetics

Usefulness

Where used

effect,

psychological

lotion. Permanent

waving

Makeup products

Preventing dental decay, bad breath

Dentifrice, Mouth wash

Alleviating acne

Acne products

Cleansing (physiological, sanitary)

Soap, Body shampoo

Sunscreening

Sun care products (sunscreens, etc.)

Preventing body odor (armpits, feet)

Deodorant products

Bleaching, removing hair (unwanted hair)

Bleach, Depilatories

Stimulating circulation (physiology, health)

Bath preparations

Treating rough skin on the hands

Handcare products

Making nails more attractive

Nail enamel, etc.

Making effect)

Perfume, Eau de cologne and other grance products

body

11.2.2. Physicochemical

smell

nice (psychological

usefulness

Examples of research being done tecting the skin from the effects absorbing and scattering agents, freckles, making the hair more which rheology is applied. 11.2.3. Psychological

fra-

on physicochemical usefulness comprises that on proof ultraviolet radiation through the use of ultraviolet effectiveness of makeup in covering liver spots and attractive through permanent waving and creams to

usefulness

In the area of psychological usefulness (aromacology of fragrance, psychology of makeup colors, etc.) the effectiveness of cosmetics in such aspects as the soothing as well as stimulating effect of their fragrance on the mind, giving the wearer more confi-

220

New cosmetic science

Permanent waving lotion Split Hair coating lotion Hair growth promoter

Makeup covering effect

Hair growth promoter

Alleviation of skin roughness

be

o

Skin whitening Wrinkle prevention

Sun care products

Cleansing agents H Deodorants Bath preparations

Psychological effect Skincare Makeup

bo

Fragrance

Fig. 11.1. Research on the usefulness of cosmetics and its effects.

dence and raising working efficiency, is studied. In this area, the results of psychological research and more recently psychoneuroimmunology and other research are being applied. The research being done in the three areas above and its effects are illustrated in Fig. 11.1.

11.3. Examples of usefulness research 11.3.1. Examples of research on physiological

usefulness

11.3.1.1. Alleviation of skin roughness^^^^ For the purpose of moisturizing the skin, the water-humectant-oil balance is extremely important and these three components exhibit complementary functions in this respect. Research has shown that a cream with a proper water-humectant-oil balance not only improves the skin surface condition but also the physiological condition of the parts under it. Let us look at the procedures and results of this research. The cream used in the research was an 0/W type with a proper balance of oily ingredients comprising hydrocarbon compounds with squalane as the main one and humec-

UsefuIness of cosmetics

221

o

Cream not applied

Cream applied

Fig. 11.2. Improvement in skin surface condition due to cream.

tants which were polymer ones such as hyaluronic acid, and polyol ones such as glycerin and 1,3 butylene glycol which are much used in cosmetics. The cream was given to a panel of 25-35 year old male volunteers (group I) to apply to their cheeks for a period of 2 weeks during the coldest part of the winter in February. For comparison an O/W type cream containing three ingredients in unbalanced proporSurface condition

c "o

E 2

(3

Mir Before After Before After Part with Part with no cream cream Group I

JL

_L

1

Before After Before After Part with Part with no cream cream Group II

Fig. 11.3. Improvement in skin surface condition due to cream.

222 New cosmetic science TWL

1.4

1II

-

1.2

o cu

1 0

C/2

08

^

L-, dJ

<

O.b

Horny Layer Moisture Content (after test)

1

Group II n_.M ^ 2 Cream

Group I

[

Group I | No cream

Group II

Fig. 11.4. Improvement in TWL, horny layer moisture content due to cream.

tions was given to group II, a panel of male subjects between 25 and 35 years in age, to apply for the same period of 2 weeks in February. The results were as follows. Fig. 11.2 shows how the surface condition of the skin has improved with the use of the cream. It can be seen that the use of a cream with a properly balanced formula has enabled the skin to regain its attractive appearance from the condition prior to using the cream in which there was disorder in the pattern of furrows and ridges. In Fig. 11.3, the skin surface of the panels of test subjects has been graded according to a points system. In Fig. 11.3, a higher number of points indicates a greater improvement in the skin surface condition. In group I the skin surface condition improved significantly but no improvement was observed in group 11. Fig. 11.4 shows the recovery in the trans-epidermal water loss (TWL) and horny layer

No cream applied

Cream applied (after 2 weeks)

Fig. 11.5. Reduction in the number of residual nuclear clusters due to cream.

Usefulness of cosmetics 223

SSB 10 p

u

Ci^

1

li

Group I

Cream

Group II

|

| No cream

Fig. 11.6. Reduction in the number of nuclear clusters due to cream.

moisture content. In group I, the cream used restored the skin's moisture retention function by reducing the TWL, i.e. the loss of moisture from the epidermis and augmenting the horny layer moisture content. Fig. 11.5 shows the result of a skin surface biopsy (SSB) to investigate the number of residual nuclear clusters. Horny layer cells formed by keratinization usually lose their nucleus but if the skin becomes rough, this process is incomplete and the nuclei do not disappear. This is indicated by the black spots in the photograph. From this we can see that when the condition of the skin improves as a result of using the cream, the nuclei disappear and the process of keratinization becomes normal. Fig.

1 PGA/PGA+ Glu

1.1

\\

t^ 1.0

FT M

Group I

Cream

Group II

|

|No cream

Fig. 11.7. Improvement in amino acid indicator due to cream.

224

New cosmetic

science

< Amino acid p roduclion in h )rn\- la\'er PC A etc.

Horny la\er ct

C^^

:)

".^=^

(Granule cell

Amino acids 0 Stratum corneum basic protein 0 Keratoh\'alin granule

Spinous cell i

M-

Basal cell

^

Assumed metabolic pathway PCA |(pyroglutamic| acid) UCA Urocanic] AcidJ Orn Cit

Ala

I

1

I

I

r-Glu-AA

' Glu I-

r-glutamyl-AA synthetase

(

I-

M

I

1

PCA I I

r-glutamyl cyclotransferase

NH3 ! His !-

-i_UCAj

histidase Urea

,

carbamoyl .phosphate

.

^

'ornithine ' carbamoyltransf erase

-•

•I Orn I

• Arg

'

argmase

'••.

^^

Pi

^1 Cit '

CO2

Asp I-

_Z_

-^i_ Alaj

aspartate 4-decarboxylase Fig. 11.8. Production and metabolism of amino acids in stratum corneum (horny layer).

11.6 shows this graphically. In group I, there has been a significant decrease in the number of residual nuclei. Fig. 11.8 shows the production and metabolism of amino acids in stratum corneum. At the stage when basal cells change to horny layer cells, the keratohyalin granules are transformed into amino acids and PCA via stratum corneum basic protein. In the assumed metabolic pathway, glutamine is converted to PCA, histidine to urocanic acid, arginine to citrulline via ornithine, and aspargine to alanine. If this metabolic process does not go smoothly, the PCA, urocanic acid, citrulline and alanine production rates drop. These production rates were investigated using the amino acid indicator to see if the metabolism was going smoothly or not. Fig. 11.7 shows the improvement in the amino acid indicator due to the cream. In group I the PCA ratio has gone up for the area to which cream was applied, showing an improvement in the metabolic process whereas no improvement was seen for group II. From this, it can be seen that the use of a cream with a proper balance of ingredients does not just improve the condition of the skin surface but also has a beneficial effect on the physiological condition of the parts underneath.

Usefulness of cosmetics

225

11.3.1.2. Effect of whitening cosmetics in preventing liver spots and freckles due to ultraviolet exposure^^^^ Concerning beauty, the things that trouble women most are liver spots and freckles. As another example of the usefulness of cosmetics we can give a whitening preparation containing arbutin designed to treat such troubles. As a description of arbutin has been given in the chapter on Cosmetics and Pharmaceutical Agents, here we will discuss an actual test on the use of whitening cosmetics containing it and the results obtained. Arbutin inhibits the activity of tyrosinase derived from mushrooms and B16 mouse melanomas and it has been shown that its inhibitory effect on tyrosinase derived from mushrooms is the competitive type. It has also been demonstrated that with a B16 melanoma culture, arbutin inhibits the production of melanin at concentrations which do not affect cell proliferation. In an in vivo test, the efficacy of a whitening cosmetic containing arbutin as its active ingredient was tested. First, in a double blind test, its inhibitory effect on pigmentation was investigated in human skin exposed to ultraviolet radiation. Fig. 11.9 shows that there was a significant difference in the degree of darkness between areas to which an arbutin and a non-arbutin containing milky lotion were applied. From this result, it can be seen that by effectively inhibiting pigmentation arising from exposure to ultraviolet light a milky lotion containing arbutin is extremely useful in preventing liver spots and freckles due to sunlight. Next the arbutin containing milky lotion was tested to see how it actually felt on use. The test was carried out for a period of one month on 38,500 subjects from all over Japan using a self reporting system. In the analysis of the results, the whole country was divided into 13 blocks and 80 persons were selected by random sampling from each block so a total of 1040 persons were used as the subjects for it. As shown in Figs. 11.10 and 11.11, 82.3% of them reported some effect. Fig. 11.12 shows the effect of the milky L value

Before exposure

7 days after

14 days after

21 days after

(t test) (p< 0.005) (n = 40) Fig. 11.9. Change in skin color (L value) with time for areas to which arbutin-containing and nonarbutin-containing milky lotions were applied.

226

New cosmetic

science

Very concerned about

^Darkness

Liver spots

Somewhat concerned about 57.2%

28.1%

22.9%

Freckles 15.3%

Not concerned about

14.7%

47.3%

35.7%

H-

29.8%

49.0%

Fig. 11.10. Subject characteristics (1040 persons used for analysis).

Great effect

Fig. 11.11. Evaluation of effect (total: 1040 pers.).

10 Makeup looked better

41.5%

Transparency achieved

37.3%

No longer concerned about darkness

36.9%

Liver spots became fainter (check other)

33.8%

Less skin roughness

21.7%

Freckles no longer prominent Now able to use bright foundation

20

30

—I

13.2% L3%

Fig. 11.12. Main items used in evaluation of effect.

40% r—

Usefulness of cosmetics 227

(%)

60h-

r-1 n

40

20 0 (n = 20I^

n nN n

C2 C3 C4 Cs iso C5 C6 C7 C8 C9 C2 ! acetic acid iso C5 \ isovaleric acid C9 : pelargonic acid C3 : propionic acid Ce '. caproic acid C4 : butyric acid C7 : enanthic acid C5 : valeric acid Cg : caprylic acid

Fig. 11.13. Olfactory evaluation of short chain fatty acid aqueous solutions.

lotion with respect to particular parameters. There were many reports of the skin feeling clearer, no longer being concerned about its darkness and that liver spots had become lighter. As the result of this, makeup looked better when it was applied. 11.3.2. Examples of research on physicochemical

usefulness

11.3.2.1. Usefulness of deodorant cosmetics^^ There is a close relationship between body odor and sweat because the unpleasant smell of body odor results from the breakdown of substances in sweat by bacteria on the skin. This odor is referred to as "sweat odor" and "body odor". "Armpit odor" and "foot odor" are produced by a similar mechanism. The following is a study carried out on the substances causing foot odor and the usefulness of preparations designed to prevent it. In an analysis of the substances extracted from the socks of a panel of subjects, iso C5, Cg, C7, Cg, C9 and Cio lower fatty acids (short chain fatty acids) were detected. Among them, the presence of isovaleric acid was particularly marked and this was the substance detected by 70% of the people as foot odor (Fig. 11.13). Next, various powders were added to a 0.5% aqueous solution of isovaleric acid and the amount of isovaleric acid consumed per 1 mg of ingredient was measured to assess the deodorizing effect. As shown by the results in Fig. 11.14, zinc oxide was the most effective in doing this, even among the metal oxides. In order to confirm the deodorizing effect of zinc oxide, it was added to the foot odor extract and the IR spectrum was observed. The spectrum showed that the lower fatty acids causing foot odor reacted with zinc oxide to form odorless fatty acid zinc salts (Fig. 11.15). In order to test the deodorizing effect in a cosmetic product a test deodorant powder spray containing zinc oxide was made and sprayed on to certain parts of both left and right feet but not others. The strength of the odor from sprayed and non-sprayed parts was compared over 31 hours. As shown in clearly in Fig. 11.16, the unpleasant odor

228 New cosmetic science

3000

biO

2000

1000

Talc

Silica Aluminum-Hydroxy-Zinc oxide hydroxy apatite chloride

Fig. 11.14. Deodorizing effect of various powders.

from the feet was suppressed in the sprayed parts but not in the unsprayed parts used as the control, providing sufficient evidence for the usefulness of the spray. Similar results were obtained when the sprays were applied to the armpit.

1.0

propionic iso-valeric. caproic acid aqueous solution -ZnO

Fatty acid metal salt

I

filtration

I

evaporation

<

0.5

4000

residue

1000 2000 1700 1500 Wave number 2RC00H + ZnO — (RCOO) zZn + H2O malodorous zinc non-malodorous water subst. oxide subst. 3000

400

Fig. 11.15. IR spectrum of foot odor treated with zinc oxide.

Usefulness of cosmetics 229

3

I2

i

>>

'Z 1 0

H[\ \

(

• Sprayed parts 1 0 Non-sprayed parts (control)

0 Before spraying

24 28 •^ Time (hours)

31

Fig. 11.16. Changes in intensity of foot odor for parts treated with spray containing zinc oxide and nontreated parts.

11,3.2.2. Usefulness of a preparation for preventing split ends^^^^ The hair problems that women in the 18-24 age group are most concerned about are split ends and broken hairs accounting for 51% of them. An investigation into the occurrence of split ends revealed that there was a correlation between the amount of split ends and the cross sectional shape of the hair (Figs. 11.17 and 11.18). As shown in Fig. 11.18, the number of split ends increases as the hair diameter indi-

Fig. 11.17. Sections of split ends.

230

New cosmetic science

Circle

t

0.9 0.8

-aCDC

0.7

1 ^

r

?

-

X

V

0.6 Hair diameter index = minor axis/major a.Kis Minor axis

0.5

i

[ v il>.

0.4 -

Major axis

Ellipse None at al

A few can be found

Many amount of split ends

Fig. 11.18. Relationship between hair cross sectional shape and split end quantity. Hair permed 2-3 times per year. * t test: signlHcant difference for 5% risk rate.

cator becomes smaller (hair becomes flatter) and for such hairs, splits beginning at the end of the major axis were observed. It was found that for people with many split ends, exfoliation of the cuticle tended to happen more easily at the ends of hairs and this was more pronounced along the major axis than the minor axis. The ease with which the cuticle peels off is illustrated in Fig. 11.19. When it peels off the hair is easily damaged. As shown in Fig. 11.20, the hair surface can be made smooth by applying a thin film of silicone resin using a cuticle coating agent which prevents any further splitting as well as dryness in the hair due to split ends. Layers 9i—

Minor axis

10 15 20 25 Distance from scalp (cm)

30

35

Fig. 11.19. Decrease in the number of cuticle layers with distance from the scalp for elliptic hairs.

Usefulness of cosmetics

a. Before application

231

b. After application

Fig. 11.20. Application of cuticle coating agent to split ends.

Fig. 11.21 shows the increase in the number of split ends when the hair was brushed 10,000 times and that the increase was greatly suppressed through the use of a coating agent. 11.3.3, Examples of research on psychological

usefulness

Though a fair amount of research has been done on the psychological usefulness of cosmetics^) we will just give two examples here. 11.3.3.1. Research ofSumiko Iwao et al. In 1981, a research group centering on Professor Sumiko Iwao of Keio Gijuku University's Newspaper Research Institute carried out an investigation together with Shiseido

25

Non-coated hair

Hair coated with cuticle coating agent (Split hair coating lotion) 4000 6000 8000 10000 The number of brushing

12000

Fig. 11.21. Effectiveness of coating agent in preventing split ends.

232 New cosmetic science

Top 3 responses for up to 24 age group 1st " I feel more confident with makeup on"

Yes

/

/

No

60%

40%

1st " I feel more positive towards other people with makeup on"

60%

40%

3rd " I feel more elegant with makeup on"

59%

41%

Top 3 responses for 25-35 age group 1st " I feel a greater sense of ease with makeup on"

/

Yes 64%

/

No 36%

1st " I feel more positive towards other people with makeup on"

64%

36%

1st " I feel more elegant with makeup on"

64%

36%

Top 3 responses for 36 and over age group

Yes

No

1st " It is inconsiderate of others not to wear makeup"

80%

20%

2nd " I feel more at ease when wearing makeup"

78%

22%

3rd " I feel embarrassed if I meet an acquaintance when not wearing makeup"

69%

31%

Fig. 11.22. Results of an investigation into the psychological usefulness of cosmetics.

on the psychological usefulness of cosmetics using 673 customers of Shiseido beauty salons in Tokyo as the subjects. From the investigation, it was found that the psychological usefulness of cosmetics could be grouped together under three headings which were: (1) maintaining social status, under which 93% of those surveyed thought it unacceptable not to be properly made up for formal work or social situations; (2) staying young both physically and mentally, under which 86% said they felt better about themselves when made up and (3) bringing out attractiveness, under which 74% responded that they felt more feminine and 53% that their husbands or boyfriends looked happy when they wore makeup. Fig. 11.22 shows the result of asking how the subjects felt when they were wearing makeup by age group. The top three responses in the up to 24 and 25-35 age groups comprised "I feel more confident", "I feel more positive towards other people", *T feel more elegant" and "I feel a greater sense of ease". In the 36 and over age group, the top three responses were "It is inconsiderate of others not to wear makeup", "I feel more at ease when wearing makeup" and "I feel embarrassed if I meet an acquaintance when not wearing makeup". Of interest is that respondents up to the age of 35 were concerned with their own behavior and the way their feelings changed while those in the 36 and over group were concerned about what other people thought and aimed to maintain a sense of self through the use of cosmetics. From this, we can see that whereas women used to put on makeup to compete sexually with other women, as their numbers in the workplace have increased they now use it more for social reasons.

Usefulness of cosmetics 233

11.3.3.2. Research of Jean Anne Graham and Albert M. Kligman^^ Graham and Kligman conducted research to see if there were any psychologically or socially related differences between women who had managed to keep a youthful and beautiful skin while aging and those who had not. Targeting women between the ages of 60 and 90, they compared people of the same age for liver spots, wrinkles, sagging skin and dark rings under the eyes, putting them either into a group having a beautiful skin with few signs of aging and one which did not, depending whether there were few or many of such features. It was found that the beautiful skin group not only felt very healthy both physically and mentally, they actively took part in social activities, were cheerful and optimistic, easily adapted to their surroundings, were satisfied with their lives, felt a zest for life and happily accepted the realities of life. In contrast, the group whose skin showed marked signs of aging seemed at a disadvantage both psychologically and socially because their skin no longer looked beautiful. These results confirmed the view that there is more to skin than just dermatological problems; its psychological and social effects were also very significant. So, Graham and Kligman went on to investigate why older people can have both attractive and unattractive skins. They found that people whose skin showed marked signs of aging had not taken sufficient care to protect it from ultraviolet radiation through the use of sunscreens or stop it drying out using moisturizers, so their skin had suffered the damaging effects of sunlight over a great many years by not being protected against it.

11.4. Future direction of cosmetic usefulness^o-i^) With people becoming increasingly older and desiring to feel more fulfilled, more emphasis is now being placed on the antiaging and psychological effects of cosmetics when considering their usefulness. In the antiaging aspect, more research is being done on the three time-worn cosmetic ideals of whitening the skin, making it look youthful again and promoting hair growth and further advances should be made in these areas. Regarding the psychological effect of cosmetics, neuropsychological and immunological research will continue and the overall result will be to help people have a better quality of life.

References 1. Ozawa, T., Nishiyama, S., Horii, K., Kawasaki, K., Kumano, K., Nakayama, Y.: HIFU (SKIN), 27 (2), 276-288 (1985). 2. Nakayama, Y., Horii, I., Kawasaki, K., Koyama, J. et al.\ J. Soc. Cosmet. Chemists Jpn., 20 (2), 111 (1986). 3. Akiu, A., Suzuki, Y., Asahara, T., Fujinuma, Y., Fukuda, M.: Jpn. J. Dermatol, 101 (6), 609-613 (1991). 4. Tomita, K., Fukuda, M., Kawasaki, K.: Fragrance J., 18 (6), 72-77 (1990). 5. Kanda, F., Yagi, E., Fukuda, M., Nakajima, K., Ota, T., Nakada, K., Fujiyama, Y.: J. Soc. Cosmet. Chemists Jpn., 23 (3), 217-224 (1989). 6. Fukuji, Y., Torii, K.: 38th General Meeting, Chubu Branch of Japanese Dermatological Association Oct., 1987. 7. Kanbe, T., Fukuji, Y., Uemura, M., Torii, K.: Symposium (The 14th Japanese Cosmetic Science Society Meeting) June, 1989. 8. Fukuhara, Y. et al\ How to Age Successfully, pp. 179-184, Kyuryudo, 1989. 9. Graham, J. A., KUgman, A. M.: J. Soc. Cosmet. Chem., 35, 133-145 (1984). 10. Ozawa, T.: Skincare Handbook, Kodansha, 1986.

234 11. 12.

New cosmetic science

Ozawa, T.: Role of Cosmetics in Aging, Ed, Takase, Y., Aging and the Skin, Seishishoin, 1986. Ozawa, T.: Cosmetics - Aging of the Skin and Homeostasis of Skin Moisture Balance , Proceedings of the Osaka Society of Dermatologists, No. 18,1991. 13. Ozawa, T.: Usefulness of Cosmetics and Position of Cosmetic Science in Society, Fragrance J., 12 (1), 15-18 (1984). 14. Ozawa, T.: Prospective Problems and Advice on Cosmetology, Fragrance J., 20 (7), 43-48 (1992).

12 Cosmetics and containers Recently, the variety of containers and container materials used for cosmetics has become extremely diverse due to progress in materials technology and the spread in the range of consumers. However, the most important function of the container is still to protect the contents. Based on this fundamental function, the most important points in container design are to improve and diversify functionality and ensure quality. The container design also plays important roles in cost consciousness, sales promotion, and environmental protection.

12.1. Characteristics required by cosmetic containers 12.1.1. Quality

maintenance

After cosmetics have been manufactured at the factory, the quality must be maintained under a diverse range of environmental conditions (temperature, humidity, light, microbial attack) during storage, shipping and usage; this is one function of the container. In addition, there must be no incompatibilities between the container and contents and the quality and safety must be maintained. 12.1.1.1. Maintaining quality of contents (1) Light penetration. If the container is transparent or semi-transparent, visible and UV light can pass through the container causing color and fragrance changes in the contents as well as decomposition of the pharmaceutical agents. To prevent this, UV absorbents and stabilizers are added to the cosmetic contents. In addition, coloring agents and UV absorbents are also incorporated in the container materials. Since it is impossible to add UV absorbents to containers like glass bottles, coloring agents and UV absorbents are often applied using surface coatings (Fig. 12.1). (2) Permeability. Although metal and glass containers are impermeable in principal to gases, liquids and solids, plastic containers do suffer to some degree from permeability. Cosmetics stored in plastic containers for long periods suffer changes in fragrance due to the permeability of the volatile perfume (materials). Some of the changes in fragrance and quality are caused by loss of part of the cosmetic ingredients while others are due to the penetration of external oxygen and water into the container contents. The degree of permeability depends on the type of plastic used, the thickness, the contents, and the external environment. For this reason, it is very important to give thorough consideration to permeability when using plastic containers for cosmetics. 235

236

New cosmetic science 100 Translucent glass -

0)

500

600

800

Wavelength (nm) Fig. 12.1. Penetration of light through various materials.

(3)

Fragrance and color changes. The type of container used can cause fragrance and color changes. In general, glass containers are extremely stable but alkali elution can cause the contents to change color as well as sedimentation, decomposition and pH changes. Consequently, low-alkali-elution glass should be used. Plastics generally contain additives (dyes, pigments, dispersants and stabilizers) and these can be eluted from the container to cause changes in the quality and fragrance of the contents.

12.1.1.2. Appropriate materials (1) Chemical-resistance. When plastic is used for the container, there is a possibility of problems such as container swelling, deformation, damage, dissolution, color change and pharmaceutical agent absorbance due to the interaction between the container and the cosmetic. Therefore, it is important to know beforehand which plastics resist the contents of which cosmetics, and the degree of resistance (Table 12.1). (2) Corrosion resistance. Various metals are used in cosmetic containers and these can sometimes cause corrosion and color change depending on the cosmetic components, fragrance components and external environment (hydrogen sulfide gas near hot springs and sulfurous gases in the air). To prevent corrosion, generally, coatings, plating and oxide films are used. (3) Photoresistance. Container materials can be affected by natural and artificial light resulting in color or quality changes. Strong sunlight in shop windows or light from fluorescent lamps in showrooms can cause color changes and brittleness in containers and cartons. To prevent this, pigments such as titanium dioxide, which effectively blocks the light, and UV absorbents are added to the container materials to increase the photoresistance. 12.1.1.3. Material safety In Japan, although the materials used in containers are not specifically regulated, in prin-

Cosmetics and containers

Til

Table 12.1. Swelling of various plastics (wt% change after 1 month at 50°C) ^^^^^^^ Plastic Material^^^

LDPE

HDPE

PP

PVC

PS

AS

Water

0.04

0.17

0.06

0.32

0.07

0.62

0.75

50% Ethanol

0.10

0.17

0.28

0.46

0.68

1.76

2.39

99.5% Ethanol

0.014

-0.031

0.45

1.19

1.33

13.95

52.44

Petrolatum

11.55

4.04

1.05

0

-0.06

-0.09

-0.05

Liquid Paraffin

10.22

3.71

1.42

-0.09

-0.04

-0.11

-0.10

PEG400

0.10

0.16

0

0.09

0.15

0.15

0.12

LDPE PP PS ABS

ABS

: Low-density polyethylene HDPE : High-density polyethylene PVC : Polyvinyl chloride : Polypropylene : Polystyrene AS : Acrylonitrile styrene copolymer : Acrylonitrile butadiene styrene resin

ciple, it is desirable that the materials are covered by the regulations for food containers (e.g. the Ministry of Heath and Welfare's Notification No. 20). In Europe and America, there are regulations concerning the use of heavy metals in general packing materials. 12.1.2. Functional design Even if a container is fashionable and beautiful, it must not be hard to use or dangerous and it must be easily disposed of after use. 12.1.2.1. Usability (1) Ergonomics. Attention must be paid to the container design to ensure that it is easy to carry and open; this can be determined by testing how the consumer actually uses the cosmetic. (2) Physical functionality. The container must be designed so that it remains functional while in use by the consumer. 12.1.2.2. Usage safety (1) Safety in use. The container must be designed so that it is safe to use in any environment, location or usage that the consumer may choose. For example, use of a glass bottle in the bathroom could result in possible harm or injury to the user if it is accidentally broken, so glass should be avoided for these types of product. (2) Safe usage. It is very important to observe how the consumer uses the product and to consider how it may be misused. For example, the shape and materials of the container must be designed so that the user may not hurt hand or finger. The usage description and illustrations should be easy to understand and promote safe usage. 12.1.3. Optimum packaging The optimum packaging for cosmetic containers and the outer packaging such as the box maintains the quality and performance of the product as well as promotes sales. Moreo-

238

New cosmetic science

ver, it should also conserve and make efficient use of resources, and be environmentally friendly. 12.1.3.1. Optimum quality level The cost and quality of a product are closely related and rising cost usually follows better quality. If the degree of product quality that consumers desire can be established, it will help to prevent complaints about the product, and this must be balanced against the cost. 12.1.3.2. Optimum quantity In Japan, when the product quantity exceeds 10 g or 10 ml, the quantity must be indicated. In addition, the permissible difference between the indicated quantity and the actual quantity must be within ±3% at 20°C (as regulated by the Ministry of Health and Welfare's Pharmaceutical Affairs Bureau (PAB) MHW Notification No. 546). In the EU, the quantity is set to a standard amount and must be indicated. In the USA, the exact quantity must be displayed, but in the EU, this is not required for amounts under 5 ml (g). 12.1.3.3. Optimum volume In Japan, to prevent oversize packaging, when the indicated quantity exceeds 30 g, the contents must occupy at least 40% of the container (Regulations concerning Optimum Packaging of Cosmetics - The Fair Trade Commission). Oversize packaging is also regulated in Germany and Australia. 12.1 A.

Economy

In the past, to enable manufacturing of low-cost high-quality products, mass production of a small product range was used, but with the recent diversification and more individual nature of consumer needs, the product range is also becoming more diverse and small-lot production is being used, requiring relevant research into production facilities and sales methods. Accordingly, an important theme is how to reduce costs for materials and distribution of manufactured products. 12.1.5. Sales promotion A final important feature of containers is sales promotion. In all the items described so far, the consumer can only appreciate the quality after buying the product. However, the container design (fashion, naming, concept, shape, and color, etc.) can be a useful vehicle for creating an impression of the product and the corporate identity (company logo, mark, etc.) which in turns expresses the company's reliability and image.

12.2. Types of cosmetic containers Cosmetic containers can be classified in various ways but this section classifies them according to form.

Cosmetics and containers

12.2.1. Narrow-mouth bottles

239

(containers)

Generally, narrow-mouth bottles describes bottles where the mouth is relatively smaller than the body. Narrow-mouth bottles are usually used for liquid products such as lotion, milky lotions, hair tonics, eau de colognes, nail enamel, and shampoos, etc. They are usually made of glass, and plastics such as polyethylene (PE), polyethylene terephthalate (PETP) and polyvinyl chloride (PVC). The best material is chosen based on the light transmissivity, permeability, compatibility, etc. The width of the mouth is adjusted to match the viscosity of the contents so that an appropriate amount can be poured out. The main type of cap is the threaded type but the snap-on type is also used. 12.2.2. Wide-mouth bottles

(containers)

Generally, wide-mouth bottles describes bottles where the mouth is about the same diameter as the body. They are mainly used for cream and gel-type products. The principal materials are glass and plastics such as polypropylene (PP), acrylonitrile styrene (SAN), polystyrene (PS), and PETP, etc. The cap is usually threaded. The inside of the cap usually has an expanded foam packing to form an airtight seal. A film is often mounted at the mouth entrance to prevent the contents sticking to the inside of the cap. The mouth entrance is often sealed with a heat shrink film to achieve the same purpose and also to show that the product is new and unused. 12.2.3.

Tubes

Tubes describes containers that are squeezed in the body section to obtain an appropriate amount of the product. They are used widely for cream products such as toothpastes, hair gels, and foundations as well as for milky lotions. The principal materials are aluminum, aluminum laminate, PE, and laminated plastics. Since the container is thin, it is necessary to exercise care when choosing tubes for products that might permeate the tube walls or bleed out. Usually, the product is filled from the end furthest from the mouth which is then sealed using heat, high-frequency energy or ultrasonic waves. In the broader definition, similar containers made by the blow molding are also called tubes. 12.2.4. Tubular

containers

Tubular containers are the long thin containers like those used for mascara and they are Main Body Spiral-type brush

Rod

Squeegee

Cap

Fig. 12.2. Composition of mascara container.

240 New cosmetic science

also used for eye liner and eye shadow. The principal materials are plastics and metals, or a combination of both. The cap consists of a thread and a rod, a spiral-type brush, regular brush or applicator at the end. When the cap is removed from the container, an appropriate amount of the product is applied to the brush, etc., applicator. The amount can be adjusted by the diameter and shape of a squeegee in the mouth of the bottle. The squeegee is usually made from rubber or PE (Fig. 12.2). 72.2.5. Powder

containers

Powder containers are used for powder products such as fragrance powders, talcs and baby powders. They do not require portability but a usage requirement is a screw or flip top. The product is loaded straight into the container or into an inner drum which is usually paper or plastic. The appropriate amount of product is applied onto a powder puff using an internal net-like structure over the powder. If the product is carried, an internal lid made of PE is usually fitted inside the container. In many cases, the container is made of plastics such as PS and SAN. The powder puff is woven from cotton, acrylic, polyester or nylon, etc. and the puff base is usually foamed urethane, etc. The net is made from nylon mesh, mounted in a paper or plastic frame. 12.2.6. Compact

containers

Compacts are containers in which the lid is hinged to the body. They usually have a mirror inside the lid and are carried and used as a cosmetic makeup tool; compacts are used widely for makeup cosmetic due to their simple convenience. The contents are mainly solid powders and cream-type foundations which are loaded into a tray which is mounted in the main compact body. The usual materials are plastics such as SAN, acrylonitrile butadiene styrene (ABS), and PS, etc.; metal types include brass, red copper, aluminum, and stainless steel, etc. Metal compacts are thinner and feel heavier and as surface processing can be done on them are much used for top-of-the-line products. The inner tray is usually aluminum or stainless steel but sometimes plastics are used. Makeup accessories include powder puff, sponge, brush and tips, etc. Recently, compacts with new functions have appeared on the market; the inner tray can be removed easily and some compacts are now airtight to prevent the evaporation of volatile components in the contents. 12.2.7. Stick containers Stick containers are simple easy-to-use and portable containers for products such as lipstick which are applied directly to the skin. In most, the stick makeup can be wound in and out of the container. As well as lipsticks stick containers are also used for foundation, eye shadow, hair sticks, and deodorant, etc. The container materials are metals such as aluminum and brass as well as plastics including SAN, PS, PP, etc. The contents are loaded in an inner holder and a screw or spiral thread mechanism is used to wind the contents in and out of the container. The materials for the inner holder are chosen based on preventing the contents falling out and compatibility of contents. In most cases, the materials are PP, SAN and polybutylene terephthalate (PBTP).

Cosmetics and containers 241

The stick mechanism can be classified basically into three types: a spiral on the outer surface of the stick holder as used for lipsticks, a screw attached to the bottom of the stick holder as used for stick foundations, and a screw running through the center of the stick itself as used for lip cream. 12.2.8. Pencil containers There are two types of pencil container; one like a regular wood pencil and another like a propelling pencil. The former is sharpened like an ordinary pencil, while the latter is ejected automatically. In some propelling types, the contents can be changed using a cartridge. The pencil contents are mainly eyeliner, eyebrow, and lip pencil. The wood pencil uses Canadian cedar for its sharpening ability but recently, some plastics are being used. The propelling pencil types usually have either screw or push mechanisms. But since cosmetics are quite soft, the screw type is more common. The materials are metals such as aluminum and brass as well as plastics. Engineering plastics such as polyoxy methylene (POM) are sometimes used for the finer parts of the mechanism. In particular, this type uses a core chuck for the thin pencil lead core and care is required to prevent the lead core from breaking inside the pencil and falling out. 12.2.9. Applicator

containers

There is no strict definition of applicator containers, but generally, the liquid contents are applied directly to the skin from the container mouth. For example, a sponge in the mouth of the container is used to apply liquid foundation or deodorant. The narrow mouth of the container is plugged by a porous stopper made of urethane covered with cloth, etc., and an appropriate amount of the liquid contents passes through the stopper to the surface. There is also a roll-on type in which a plastic ball is mounted in the mouth of the container and the rotating ball is used to apply the contents directly to the skin. This type has been used for anti-perspirants and recently for fragrances.

12.3. Cosmetic container materials Since cosmetic containers are available in a huge variety of forms and designs depending on the usage, a wide number of materials are also used to manufacture them. Table 12.2 lists the different types of materials used. Of the extremely large number of material types, this section describes the main materials and production methods used for these containers. 12.3.1. Types of materials 12.3.1.1. Plastics Plastics are widely used due to their ease of processing, and wide availability in different transparencies, opacities, colors, external appearance, etc. Plastics are broadly divided into thermosetting plastics and thermoplastics.

242 New cosmetic science Table 12.2. ClassiHcation of materials used in packaging cosmetics Material Glass, Ceramic, Stone

Main Use Bottles, Caps, Decoration

Plastic, Rubber

Bottles, Caps, Containers, Tools, Parts, Protective parts

Metal

Containers, Caps, Parts, Decoration

Paper, Wood, Thread, Cloth

Labels, Cases, Protective Combs, Tools

Horn, Tusk, Leather, Hair, Sponge

Decoration, Combs, Tools

parts. Decoration

parts.

Thermosetting plastics undergo a chemical reaction when heated and set after passing through a molten stage. If they are overheated, they break down. Typical thermosetting plastics are melamine, urea, and acryl, etc. Recently, they are being used to some extent for special purposes. Nitryl butadiene rubber (NBR), isobutyl isoprene rubber and silicone rubber are also thermosetting plastics and they are used in mascara squeegee, rubber droppers and packing materials. Thermoplastics become liquid when heated and solid when cooled; if they are then heated again, they become liquid again. Consequently, they are useful in automated forming processes and many thermoplastics are now being used. (1) Low-density polyethylene (LDPE). LDPE is semitransparent and lustrous and since it is soft and supple it is used for squeezable bottles and tubes, stoppers, and packings, etc. Its weakness is that when alcohols and surfactants, etc., come into contact with it, stress cracking occurs. (2) High-density polyethylene (HDPE). HDPE is a milky-whitish color, non-lustrous and is almost opaque. It is used for bottles and tubes for lotions, milky lotions, shampoos, and rinses. (3) Polypropylene (PP). PP is semitransparent and lustrous; it is very resistant to chemicals and has good shock resistance at ordinary temperatures. A special characteristic is its ability to withstand repeated bending so it is often used to form the hinge mechanism in the so-called flip-top cap. It is also used in jars for creams and in various types of cap. (4) Polystyrene (PS). Polystyrene is tough, transparent and lustrous. It is easily molded and has good dimensional stability. Its weakness is that it is easily attacked by chemicals and it has very poor shock resistance but this has been improved in highimpact styrene (but poor transparency). It is commonly used in compacts and stick containers. (5) Acrylonitrile styrene copolymer (AS, SAN). AS is a transparent, lustrous, shockresistant material with good resistance to oils so it used in containers for creams, and in compacts and stick containers; it is also widely used for caps, etc. (6) Acrylonitrile butadiene styrene (ABS). ABS has improved shock resistance over SAN, so it is used in products such as compacts requiring high shock resistance. However, a weakness is an inability to tolerate perfume and alcohols. Chemical plating or vacuum metallizing are used to give ABS a metallic feeling.

Cosmetics and containers 243

(7)

(8)

(9)

Polyvinyl chloride (PVC). Since PVC is a low cost, transparent, easily processed material, it is used widely as bottles for rinses and shampoos and refillable containers. However, since it produces highly-toxic pollutants when burned, it is banned in many countries from the environmental conservation viewpoint. In Japan, some businesses are also rethinking its use. Polyethylene terephthalate (PETP). PETP is a tough lustrous material with a transparency close to that of glass. It has a higher image than polyethylene and polyvinyl chloride due to its external resistance and chemical durability so it is used for bottles for better quality lotions, milky lotions, shampoos and rinses, etc. Other plastics. Other plastics such as polyamide (PA), ethylene vinyl alcohol copolymer (EVOH) and polyoxymethylene (also called polyacetal) (POM) have high chemical resistance and perfume stability, they are used in some laminated containers and parts requiring high strength.

12.3.1.2. Glass (1) Soda glass. Soda glass is normally used for transparent glass bottles. Generally, it is made from silicon oxide, calcium oxide and sodium oxide as the main constituents with trace amounts of magnesium and aluminum oxides. Colors are produced using metal colloids and metal oxides. Soda glass is used widely for bottles for lotions and milky lotions. (2) Potassium/lead glass. The principal ingredients of this glass are silicon oxide, lead oxide and potassium oxide. High levels of lead oxide produce glass with a high transparency and refractive index called crystal glass. This type of glass is used for high-class perfume bottles, etc. (3) Opaque glass. This glass contains colorless fine crystals (sodium silicofluoride, etc.) in the colorless translucent glass matrix. These crystals reflect light and make the glass look milky. When the crystals are small, a bottle made from this glass is called a jade bottle and when they are large an alabaster bottle. 12.3.1.3. Metals (1) Aluminum. Since aluminum is light and easily machined, it is used widely for aerosol cans and containers for lipsticks, compacts, mascaras and pencils, etc. Alumite surface processing or coating is used for surface decoration and to prevent corrosion. (2) Brass. Brass is an alloy of copper and zinc. Since it looks similar to gold in external appearance and has a high density, it is used for items like compacts or lipsticks with plating or coating. (3) Steel and stainless steel. Steel rusts easily so it must be tin-plated or coated to prevent rusting for use in aerosol cans. When it is alloyed with chrome and nickel, corrosion-resistant stainless steel is produced. 12.3.2. Forming and processing

methods

12.3.2.1. Plastic forming methods The method of forming plastic depends on whether the plastic is thermosetting or thermoplastic.

244

New cosmetic science

(1)

Compression molding. Compression molding is the typical method used for thermosetting plastics. Powdered or grained raw material is poured into a hot mold where it sets at high pressure and temperature after a fixed period. (2) Injection molding. In this method, hot molten plastic is injected at high speed under pressure into a cooled mold and allowed to cool to a fixed temperature; after setting, the mold is opened and the molded product is removed. This method is commonly used for compacts, caps and stoppers, etc. (3) Blow molding. This method is used for forming hollow products such as bottles; it is also called the hollow or blow forming method. (a) Extrusion blow. In this method, the heat-softened plastic is extruded into a tube, and then pinched with molds and air is blown in to create the hollow. It is commonly used to produce narrow-mouth bottles. (b) Injection blow. In this method, the mouth and body are formed by injection molding; the product is then forced into a blow die and air is blown in. This method is used when the internal diameter of the body is much larger than that of the mouth. (4) Extrusion molding. In this method, the heat-softened plastic is extruded from a circular nozzle. A two- or three-layered tube body can be formed by using double or triple extrusion nozzles. (5) Vacuum forming. In this method, a vacuum is formed between a heat-softened sheet of plastic and the mold and the sheet is drawn into the mold to form the container. This method is commonly used to produce refills for makeup cosmetics. 12.3.2.2. Glass forming methods (1) Blow forming. In this method, molten glass is forced into a mold and air is blown in to create the shape. This method is used principally to produce narrow-mouth bottles. (2) Press and blow forming. In this method, the molten glass is pressed into a primary die to make the thickness uniform and then it is transferred to a blow die into which air is blown. (3) Press forming. In this method, the molten glass is loaded into a cavity and then a core is forced in from the top. This method can only be used to form containers in which the internal diameter of the mouth and body are the same, or the internal diameter of the body is smaller than that of the mouth. 12.3.2.3. Metal forming methods (1) Pressing. In this method, the final form is achieved by a series of pressing operations from the original flat plate using a series of cores and cavities. It is used to produce containers for lipsticks and mascara-type products. (2) Impact forming. This method uses the ductility of aluminum to extrude a container from a thick plate under high pressure in one continuous operation. It is typically used to produce aluminum cans for aerosols and aluminum tubes. (3) Other methods. Other metal forming methods include electrotyping and diecasting.

Cosmetics and containers 245

12.4. Design and quality assurance of cosmetic containers 12.4. L Container design procedure To design a cosmetic container with the fewest possible problems, first, it is necessary to clarify the objectives of the container design based on the product planning concept. The following points should be included in the design basis. (1) Container type and use/non-use of refill (2) Limitations on design due to content characteristics and quality assurance (3) Examination such as container material and form (4) Usage and usability considerations such as usage amount of contents, usage condition and portability (5) Confirmation of relevant regulations (6) Target market The actual container is designed on the basis of these design objectives. Naturally, the container design will play a part in making the product fashionable, but it is also closely connected with the functionality and the usability of the product. For this reason, before progressing to mass production, it is essential to examine each aspect carefully using trial production or models. The following items should be given full consideration before determining the container specifications. (1) Evaluation of test product based on material testing method (2) Confirmation of industrial property rights (3) Confirmation of cost (4) Close consideration of design from mass-production viewpoint (5) Consideration of environmental safety Moreover, before entering mass production, it is best to move to small-scale production to confirm items such as the quality stability and manufacturability that could not be pre-confirmed using test products. 12.4.2. Material test methods and specifications To confirm that the designed cosmetic container meets the required design quality and to ensure that there are no problems in the market with the mass-production quality, it is necessary to pay sufficient attention to quality assurance at each stage in the commercialization process. At this time, every consideration should be given to the final form of the container, its construction and materials, its processing, usage method and condition, and its distribution route, etc. To this end, it is essential to conduct material tests for relevant assurance items. 12.4.2.1. Material test method Generally, the following items are usually considered in assuring container quality. (1) Confirming content assurance. Confirms stability of contents, pharmaceutical agent's stability of quasi drug products; tests for fragrance change, color change, breakage and falling-out, of stick products such as lipstick, etc.

246 New cosmetic science

(2)

Confirming material suitability. Test for corrosion, fragrance change, color fading, brittleness, elution, cracking, safety, etc. (3) Confirming function. Test for ease of opening and closing, strength of assembled parts, loss of decorative parts, scratching, airtightness, weight loss of contents with time, etc. (4) Confirming basic specifications. Confirm external appearance of container, dimensions, volume, etc. The appropriate material test must be performed for these confirmation items. Typical tests are: temperature, humidity, hot water, thermal shock, compatibility, alcoholproofing, waterproofing, saltwater-proofing, perspiration-proofing, wash-proofing, stress cracking, pressure-proofing, drop-proofing, durability, wear-proofing, and transportproofing. The important items for each of these tests are listed below. (1) Obviously it is important to make reference to previously-used containers, but in the case of new containers, sufficient attention must be paid to usage methods and usage conditions, etc. (2) It is important not to stop with assurance of the container itself; for example, it is important to assure the joint, etc., between the contents and the container as in lipsticks, etc. (3) Usage tests should be performed using either in-company monitors or general monitors to examine container usability and portability, etc. (4) Keep an open mind about using severe or accelerated test methods to shorten the test period and prevent the occurrence of problems in the market place. 12.4.2.2. Material specifications Lastly, it is important to create materials specifications for each type of product and to use mass-production quality control methods based on the results of related material tests. If the materials specifications are examined, it is possible to perform a certain test under a certain condition and to determine that there will be no problems with the product at a certain quality level. In particular, it is important not to exceed the predetermined required quality level by using assessment of the quality level based on past experience, typical examples of previous products that caused problems, and experience of skilled staff.

12.5. Trends in container materials 12.5.1. Materials and processing

methods

The materials and processing methods used to manufacture cosmetic containers have changed greatly in accordance with developments in materials science. As an example, until recently, glass bottles have been used widely as cosmetics containers due to their ability to preserve the contents and their transparency. However, since the development of the PETP bottle, there has been a rapid change to this material due to its added advantage of light weight, transparency, and stability.

Cosmetics and containers 247

As a result of developing these types of new materials and processing methods, it has become possible to produce excellent cosmetic containers and applicators, etc., with new forms and different feelings on use, that could not be manufactured previously. Moreover, in recent years there has been great progress in laminated plastics technology and lamination of different types of materials in PE used in cosmetic containers, which has made it possible to produce a variety of properties that could not be achieved with a single PE layer. For example, the cosmetics are now better protected by lamination of plastics with excellent oil resistance and those with little gas or fragrance permeability. Furthermore, when a lustrous plastic is laminated on the outside layer, it is possible to give the container a shining appearance. Further, with advances in surface processing technology such as development of plastics that are cured and hardened instantly by UV light, it has become possible to improve the hardness of surfaces and wear resistance and such technologies are being applied to cosmetic containers. For example, virtually scratch-proof containers can be produced by coating a plastic container with these materials and the same technology is being applied to printing inks, etc., for containers. Progress is also being made in vacuum metallizing of metallic elements such as aluminum on the surface of other plastics making it possible to achieve various metallic colored effects. With the rapid progress being made in these new technologies, in the future, we can expect to see further developments in new materials and processing methods which will surely be applied to cosmetic containers. 12.5.2. Environment

friendliness

The nations of the world are looking at positive methods for preserving our natural environment. The cosmetics business is also attempting to contribute to environmental preservation, conservation of natural resources and recycling. Environmentally-friendly substitutes have already been found to replace ozone-damaging fluorochlorocarbons used as a propellant in aerosols, recycled paper is being used in packaging, the amount of plastics used in containers is being reduced, and refillable containers are being used; these changes are helping reduce the amount of garbage generated by packaging and the amounts of poisonous gases produced by incineration of plastic waste. Further, a great deal of research is being conducted into biodegradable plastics and the appearance of new environmentally friendly materials can be expected in the future. Moreover, the future will also see progress in recycling with greater use of reusable containers and materials recovery. It is important that new container designs give full consideration to the needs to protect the environment.

13 Aerosol technology in cosmetics In physicochemical terms, an aerosol is a colloid state in which very fine particles of a solid or liquid are dispersed in a gas. The insecticides and hairsprays first developed are aerosols in the original sense but the word aerosol is also applied as a blanket term to any product in which a liquid or solid is discharged from a pressure resistant container using the pressure of a gas. As they are very functional, aerosols are widely used for cosmetics. Aerosol products are classified as follows according to the form of the contents when they are discharged from the container. (1) Mist-form products: hairspray, etc. (2) Powder-form products: powder spray, etc. (3) Foam-form products: hairstyling foam, etc. (4) Paste-form products: creams, etc. Cosmetic products frequently use the mist and foam forms.

13.1. Principle of aerosols and their components 13.LL

Principle of aerosols

Aerosols contain a substance to be discharged and a propellant gas sealed in a pressure

Actuator (gas phase)' •Propellant

* * II w

- Valve mechanism

liquid phase) 'concentrate r ^^^.^^^^^ 11 , resistant + propellant ^. ' contamer -Dip tube

Fig. 13.1. Components of an aerosol. 248

Aerosol technology in cosmetics

a. Valve closed

249

b. Valve open

Fig. 13.2. Valve opening and closing mechanism.

resistant container. The pressure of the propellant discharges the contents. If the contents are a solubilized system containing 40-70% liquefied gas, they are sprayed out as a mist, but if they are an emulsion system containing 5-15% liquefied gas, the contents are discharged as a foam. 13.1.2. Components of an aerosol An aerosol product consists of the following: (1) Contents to be discharged (concentrate): liquid, powder, etc. (2) Propellant: liquefied gas, compressed gas (3) Spraying devices: valve, actuator (4) Pressure resistant container: metal, glass, plastic Figs. 13.1 and 13.2 show how aerosols operate. The contents of the aerosol are under pressure due to the pressure of the propellant so depressing the actuator on the top opens the valve and the liquid phase (concentrate + propellant) is discharged. Releasing the actuator closes the valve and stops the discharge of the contents.

13.2. Aerosol propellants There are two types of aerosol propellant: liquefied gas and compressed gas. 13.2.1. Liquefied gases A liquefied gas is in the gaseous state at room temperature but is easily liquefied when pressure is applied. As the gas is in both the gaseous and liquid state inside a sealed container, the pressure remains stable.

250 New cosmetic science

13.2.1.1. Liquefied petroleum gas (LPG) LPG consists of such lower hydrocarbons as propane, butane and pentane and its pressure is regulated by varying their proportions in the mixture. LPG is a flammable gas which is cheap in price and whose components have little smell. Due to the high inflammability, safety must be raised by regulating the force of the discharge and its amount, which can be done by carefully selecting the formula of the concentrate as well as the type of valve to be used. 13.2.1.2. Dimethyl ether (DME) DME is highly soluble in water and, when together with the resins used for setting purposes in hairsprays and other such products, the mutual solubility is very good. Thus, in hairsprays, it is either mixed with LPG or used by itself. As DME is also highly inflammable, the same precautions as for LPG must be taken. 13.2.1.3. Chlorofluorocarbons Chlorofluorocarbons is a general term applied to substances which have chlorine, fluorine, carbon and hydrogen in their molecule and low boiling points. They have seen wide use as propellants for aerosol products up to now on account of their stability, inactivity and lack of toxicity. However, when it was discovered that chlorofluorocarbons were destroying the ozone layer, a worldwide move to ban their use was started. As a result, chlorofluorocarbons which do not destroy the ozone layer or have any other adverse effects on the environment are now being developed. 13.2.2. Compressed gas Compressed gas applies to gases like nitrogen and carbon dioxide which do not liquefy at low pressures and room temperatures. Such gases are introduced into the container in the compressed state but, as they do not dissolve in the concentrate, the pressure is exerted from a gaseous phase above the concentrate. Unlike liquefied gas, it is not necessary to consider mutual solubility, reactivity or inflammability. However, it is necessary to consider the use of special valves and actuators because the pressure inside the container drops off as the aerosol is used.

13.3. Aerosol concentrates (discharged substances) There are a large variety of concentrates which are liquid, powder or cream in form. For aerosols, it is necessary to thoroughly consider the type of concentrate, selection of the propellant gas, concentrate/gas ratio and setting of the gas pressure in accordance with the discharged state, method of use and utility of their contents. Aerosol concentrates are subjected to the following tests to ensure that there are no problems with them before formulae are made up.

Aerosol technology in cosmetics 251

13.3J. Solubility test The solubility of the concentrate in the gas is tested at various temperatures because there is the possibility of precipitation and separation of the ingredients comprising a concentrate when it is mixed together with a gas. 13.3.2. Internal pressure test As the discharged state of the contents is greatly affected by the internal pressure, the internal pressure of concentrate/gas mixtures is tested for fluctuations at various temperatures in order to obtain the optimum discharged state. This is also done to ensure that it is within the permissible range in the regulations. 13.3.3. Discharge test The state of the discharge and that of the spray are checked at various temperatures to ensure that the utility stays constant within the temperature range of normal usage. 13.3.4. Low temperature test As the viscosity of some concentrates could rapidly increase and there could be precipitation or separation of their ingredients at low temperatures, the stability and viscosity are tested at -30°C to -40°C to see what would happen in the case of cold filling. 13.3.5. Other testing Concentrate pH, specific gravity, its effect on the container, viscosity and stability at various temperatures are also tested. It is necessary to take particular care with concentrates which are not very soluble in propellants and those which have high viscosity.

13.4. Aerosol containers 13.4.1. Pressure-resistant

containers

Pressure-resistant containers for aerosols are made from metal, glass or synthetic resins. As the regulations in Japan stipulate that there must be no deformation up to 13 kg/cm^ or destruction of the container up to 15 kg/cm^, it is necessary to make designs for each type of material that can withstand these pressures. However, when designing containers for other countries, it is necessary to check the regulations governing pressure resistance because they vary from country to country. The following describes the various kinds of pressure resistant containers and their features.

252 New cosmetic science

13.4.1.1. Aluminum cans Generally speaking, aluminum cans have their bottoms and middle sections made as one unit and a coating is applied to their inner surface. Having high corrosion resistance to aqueous concentrates, they are frequently used for aerosol cosmetic products. 13.4.1.2. Tinplate cans Tinplate cans are easily corroded by aqueous concentrates because they are made by just coating iron with tin; they are used mainly for non-aqueous solutions. 13.4.1.3. Glass containers As glass containers are rather fragile, the regulations in Japan stipulate that their volume must be not more than 100 ml and they must be covered with a plastic. 13.4.1.4. Plastic containers Examples of plastics currently used for aerosol containers are polyethylene terephthalate (PETP) and poly aery lonitrile (PAN). With plastics it is necessary to make a thorough consideration of their chemical resistance and permeability with respect to the concentrate and propellant gas. As they are treated in the same way as glass containers by the regulations in Japan, they are used for small volume products at present. 13.4.2. Valves, actuators, spouts and caps The special characteristics of aerosol products are largely ensured by the concentrate and the propellant gas but the state in which the product is discharged often varies depending on the type of valve, actuator (used when the product is sprayed out as a mist), and spout (used when the product is discharged other than in mist form) mechanisms used. A consideration of these items is therefore also very important. 13.4.2.1. Valves Fig. 13.3 shows the components of an ordinary valve. The valve controls the state of the aerosol contents when they are discharged as well as the amount of the discharge. Various types of valve are used depending on how the aerosol is to be used. Many mist-form products have a vapor tap orifice provided in the housing to mix the gas in the gaseous phase in order to make the mist finer and reduce inflammability. In foam-form products which are designed to be used inverted, it is normal to dispense with the dip tube and provide a few slits in the housing. Another important requirement for valves is that they seal the gas in the container. It is also very important to consider whether the sealing material used for such components as the stem gasket and the cup gaskets is suited to the concentrate formula and the gases used. 13.4.2.2. Actuators and spouts Actuators and spouts form the outlets through which the aerosol contents are discharged. For mist-form products, a special mechanism (mechanical breakup) is employed to make the liquid flow turbulent in order to achieve a very fine spray. In foam-form products a terminal seal mechanism may be used when the foam does not stop readily.

Aerosol technology in cosmetics 253 (1) Actuator -i (2) Mounting cup (3) Cup gasket ]

(4) Stem gasket (5) Stem (6) Spring (7) Housing

(8) Dip tube

Fig. 13.3. Components of an ordinary valve.

13.4.2.3. Caps Caps are used to protect the valves and actuators of aerosols and their use is stipulated in regulations in Japan. However, if there is a mechanism to prevent the contents from coming out when the actuator is pressed, this requirement does not hold.

13.5. Regulations on aerosols As aerosols differ from other cosmetic products in that they use pressurized gases, they are subject to the regulations. The major regulations of Japan's Pressurized Gases Control Law are as follows: (1) Toxic gases must not be used in the manufacture of aerosols. (2) Pressurized gases used as the propellants for aerosols applied to the human body (excepting those stipulated in notifications) must not be inflammable. Table 13.1. Typical precautions in use (for hairspray, etc.) Caution : Inflammable Material (white letters on red background) As this product contains a gas under pressure and inflammable material, the following cautions must be observed : 1. Do not point towards naked flames when used. 2. Do not use in the vicinity of stoves, gas ranges or other sources of fire. 3. Only use in small amounts when there are sources of fire in a room. 4. Do not leave in places where the temperature is 40°C or above. 5. Do not incinerate. 6. Dispose of only when all the contents have been used.

254

New cosmetic science

r\

r\

r\

r\ MS .S be

03

biO C

o

1

o

r^

/^

o

§ c

^ O bfl ^

U)

'S

o u

O'

\^

Inspecting materials

Concentrate weight check

ve.

O

Pressure check Measurement of Net weight check internal pressure (gas+concentrate) Measurement of container Inflammability internal pressure inspection

Fig. 13.4. Manufacturing process chart.

(3) (4) (5)

The pressure of the gas in the container must not exceed 8 kg/cm^ at 35°C. At 35°C the volume of the aerosol must not exceed 90% of the container volume. A container containing an aerosol must have either the manufacturer's name or symbol, manufacturing lot number and precautions in use printed clearly on it (Table 13.1). For more detailed information on gases, containers, manufacturing methods, etc., the reader may refer to Paragraph 27 in Article 12 of Regulations for the Safety of Ordinary Pressurized Gases in the Pressurized Gases Control Law and the Ministry of Trade and International Industry's Notification No. 203 (dated June 4, 1991) in Japan. Several other countries have their own regulations and standards governing aerosols; for example the regulations in DOT Tariff No. 23, 173 and 306 and the FDA regulations in the USA and BS 3914 Aerosol Dispensers Following the EC Directive in the UK.

13.6. Aerosol manufacturing methods Before going on to mass production, it is necessary to carry out various production trials to make thorough checks on such items as product stability, container corrosion and gas permeability. 13.6.1. Manufacturing

processes

The normal manufacturing processes are shown in Fig. 13.4. (1) In leakage inspection, all products are checked for gas leaks by placing in hot water at 55°C for 2-3 min. (2) In the discharge inspection, the aerosol is discharged for several seconds as required. (3) The internal pressure and inflammability testing is carried out in accordance with the regulations.

Aerosol technology in cosmetics

255

When aerosols are mass produced, complaints may arise due to variations in production conditions so it is necessary to have them as uniform as possible in order to ensure product quality. 13.6.2. Filling methods for propellant gas The filling methods are cold filling and pressure filling. There are two types of pressure filling: under-cup filling and through-the-valve filling. 13.6.2.1. Coldfilling The concentrate and gas are cooled before filling, the gas being liquefied beforehand. This method is not used much nowadays. 13.6.2.2. Under-the cup pressure fdling After putting the concentrate in the container and inserting the valve, removing the air through the gap between the valve and the container, the gas is put in and the valve is crimped in place. This method is used for such products as hairsprays which contain a lot of gas. 13.6.2.3. Through-the-valve pressure fdling After putting the concentrate in the container, removing the air and crimping the valve, the gas is injected under pressure through the orifice in the valve through which the aerosol contents come out. This is a very accurate filling method and is used for foamform products which use small amounts of gas.

13.7. Precautions when using aerosol cosmetics To ensure the safe use of aerosol cosmetics, attention should be paid to the following points. (1) Cautions regarding pressure. It is dangerous to used aerosol products at temperatures above 40°C because the pressure increases. Low temperatures cause the internal pressure to drop making it difficult for the product to be discharged properly. (2) Inflammability cautions. As they use inflammable gases and inflammable ingredients are much used in their concentrates, aerosols must not be used near naked flames. Aerosols must not be incinerated because they could explode. (3) Disposal cautions. Aerosols must only be disposed of once all the gas has been used up. In the case of bag in cans, the gas should be discharged in accordance with the displayed cautions for this. Any gas remaining could cause fires in garbage when in the garbage truck or other places. (4) Usage cautions. The displayed method of use must be observed. Products on the market comprise those which are used upright, those which are used inverted and those which are used in all attitudes. Non-observance of the displayed method of use may cause the gas to escape rendering the aerosol unusable.

256 New cosmetic science

13.8. Recent developments in aerosol technology Due to their convenience, the use of aerosol cosmetics has been increasing in recent years. The following describes special types of container which have been developed for them. 13.8.1. Special aerosol containers Special aerosol containers comprise different types of compartment can using either an inner bag or piston system. 13.8.1.1. Inner bag system This type of compartment can has a soft inner bag (made from PE or soft aluminum) which is filled with the aerosol contents while the outer part of the container is filled with the gas. The pressure of the gas squeezes the inner bag causing the aerosol contents to be discharged. 13.8.1.2. Piston system In this type, there is a piston inside the container. The part of the container above the piston is filled with the aerosol contents and that below it with gas, the pressure of which pushes up the piston valve discharging the contents from the container. These types of double container have made it possible to make high viscosity concentrates into commercial aerosol products and are also good for aerosols in which the concentrate should be discharged by itself as the concentrate and gas are separated inside the container. 13.8.2. Making aerosols environment

friendly

When designing aerosol products, it is necessary to consider such environmental aspects as effect on the ozone layer, atmospheric pollution and global warming. With this in mind, positive efforts are now being made to reduce the amount of gas used and develop containers which use no gas at all. As examples of the latter, research is now being done on manual atomizers, electric sprayers, compressed air and other systems for mist-form products and, in the case of liquid-form products, dispensers and systems which discharge the concentrate as a foam. Some of these systems are already being applied in commercial products.

14 Analytical chemistry of cosmetics The analytical chemistry of cosmetics can be considered under two broad headings: the analysis of cosmetic raw materials and that of the cosmetic products themselvesi"*'^^-^^^ However, for our present age in which great advances in and constant improvements to analytical technologies are being made, not only for cosmetic raw materials and the base ingredients of cosmetic products but also for various active ingredients and additives present in cosmetic products at fairly low levels, the scope of our discussion of analysis must be expanded to include not only cosmetics but the biological substances in the skin, nails and hair that they are used on as well. As there are manuals and reviews for the analytical methods for each raw material and product category, in consideration of diversification in formulations, arranging them with an emphasis on analytical technologies should make it easier to apply what is said in this chapter to the analytical instruments which are currently available. As the manuals and reviews that are currently available fully explain the principles of analytical procedures and give clear details of how to carry them out, efforts have been made in this chapter to give as many examples of actual applications as possible.

14.1. Analysis of cosmetics The analysis of cosmetics can be divided into three broad categories. The first of these is the analysis required by the official regulations from the viewpoint of safety to ensure that the raw materials used in cosmetics are of high quality. The second is analysis carried out to guarantee their ingredient content and the third, as an extension to that required by law, further analysis necessary to guarantee that products meet the higher level and more sophisticated quality standards of cosmetics manufacturers themselves. As analysis has come to play an increasingly important role not only in the aspect of quality assurance but also in the forward looking aspect of development, we must make efforts to develop new analytical technologies for this to be based on. Though rapid advances have been made in instrumental analysis and computer data processing techniques and analysis has become more sensitive, faster and automated with the advent of more advanced reagents and apparatus, the task for cosmetics analysis in the future will be to see how such advanced technologies can be applied in the best possible way to the fundamental operations of separation, qualitative and quantitative analysis to achieve the desired objectives. In this sense, it is very important to have a good understanding of the application of analytical techniques to the analysis of cosmetics.

257

258 New cosmetic science

14,1.1, General separation

techniques

General separation techniques are extremely important because, from the viewpoint of analytical chemistry, both cosmetics and their raw materials are often mixtures of a large number of ingredients. Because of the large quantity of samples that can be handled and their direct application to gravimetric analysis, on which quantitative analysis is initially based, general separation procedures are just as widely used as column chromatography (described in next section) and they are particularly useful in overall analysis on cosmetics which does not usually require high accuracy. Table 14.1 lists general separation techniques and shows how they are applied in analysis on cosmetics. Among them, the solvent extraction method using centrifugation is a very convenient unit separation technique if a proper solvent is chosen and has been in use for some time as a fairly high accuracy analytical technique^^). Fig. 14.1 shows how it is used together with other analytical techniques in the analysis of a foundation Table 14.1. General separation techniques and their use in analysis on cosmetics. Separation technique

Description of basic technique

Applications

Distillation, evaporation

Place in water bath to separate Removal of water, ethanol, volatile residues silicones, propylene glycol and other Separation of d i s t i l l a t e s and solvents Moisture determination (xylene disazeotropic mixtures tillation method) Alcohol number, ammonium test procedures Water soluble monomers

Centrifugal separation (filtration)

Separation of substances soluble in certain solvents from those insoluble in them.

Fractional precipitation

Separation through precipitation by Separation of resins and plasticizers adding poor solvents to good sol- Separation of nylon from metacresol solution of nylon (acetone) vents

Liquid-liquid extraction

Separation using 2 immiscible sol- Separations of oils and fats in a surfactant vents Separation of counter ions from ionic surfactants

Ashing

Decomposition at high temperature

Separation of organic and inorganic substances Separation of inorganic substances and nylon powders (metacresol) Separation of inorganic substances and polyethylene (hot toluene, xylene) Separation of inorganic substances and metallic soaps (hot benzene) Separation of inorganic substances, oils and fats, surfactants and viscous substances, and water soluble polymers (hot water, ethanol)

Separation of inorganic substances

Analytical

chemistry

of cosmetics

259

-/ Sample j

^GC" Determination of volatile constituents (water, PG, 1,3-BG, alcohol), glycerin

Place in steam bath or 105°C air bath

I

Non-volatile constituents h n-hexane-ethanol ( 1 : 1 ) , etc. Centrifugal separation and extraction

,

\

,

Soluble constituents i

Insoluble constituents IR, XRD, AES

L

I Determine outline composition , [J3_C-NMR, GC _(;MU)_^ AES | Hot benzene Centrifugal separation and iH extraction Insoluble constituents

Soluble constituents

Powders (organic) XDR, FXR, IR

Metallic soap

^Organic^ IR, AES xo^stituents^ N (dispersibility in water) HCl Yes Petroleum ether extraction Petroleum ether extract

Hot toluene or Fatty acid \^- Metacresol ^ -6NHC1 xylene GC Reflux extraction Centrifugal separation Reflux extraction ^ ^ ^ and extraction Extract , ^ Acetone i Precipitate Soluble constituents Extract Nylon Polyethylene Amino acid (silk powder and other hydrolyzed proteins) IR ^^C-NMR IR, Pyrolysis GC Amino acid analyzer Fig. 14.1. Flow chart for analysis of foundation.

and, from it, we can see the importance of the solvent extraction and centrifugation in the total scheme of analysis. The separation of inorganic powders from each other is a typical example of something which is extremely difficult to carry out without changing their form and state, even using the sophisticated separation techniques described in the following. However, using a proper acid-alkali combination, the separation is possible without changing the form and state in some cases. 14,1,2, Column

chromatography

Column chromatography is an excellent separation technique which is essential to the analysis of cosmetics. With it, a large quantity of samples can be handled. The typical

260

New cosmetic

science

type used for analysis on cosmetics is adsorption (liquid-solid) chromatography which uses such substances as silica gel and alumina. As there is no device for continuously monitoring the eluted components, in order to widen its scope of use, it is necessary to employ a standard mobile phase system, such as stepwise elution, and to analyze the eluted components by some other means because the separation varies with the activity of the adsorbent and the amount of solvent used. Despite this, it is a very effective separation technique for cosmetics because they are mixtures of large numbers of ingredients. Table 14.2 gives details of the mobile phase systems in silica gel adsorption chromatography, ion exchange chromatography and reversed phase partition chromatography, and the elution patterns of typical cosmetic constituents. In addition to analysis on cosmetics, column chromatography can be used to analyze the composition of oils, fats and waxes, including lanolin. In this case, non-aqueous ion exchange chromatography^-^) and chromatography employing urea adduction^) are used, and the separation is performed under warm conditions. 14.1.3. Gas

chromatography

Gas chromatography (GC) is an essential tool in the analysis of cosmetics because in addition to being used as a separation technique, it can provide qualitative information by indicating retention times, it is easy to use in quantitative analysis and, as described later, it can be used in conjunction with other analytical technologies (mass spectrometry, infrared spectrophotometry) with no fluctuation in performance. It is mainly used for identification testing on cosmetic raw materials, especially those having an alkyl chain composition. Table 14.3 shows how GC is used in analysis on cosmetics. Though it is used mainly in quantitative analysis on materials broadly defined as volatile substances, as mentioned earlier, it is also used in alkyl group composition and polymerization degree analyses. It can also be employed to identify the types and sources of oils, fats and natural waxes from their composition patterns^^\ Though no analytical conditions have been indicated in the table, with the exception of special cases, if a packed column employing a silicon liquid phase or a fused silica capillary column is used, GC can be applied to the analysis of most compounds with high carbon numbers (total carbon number up to 50-60). For GC, it is necessary to make volatile derivatives of samples to be analyzed, which are usually trimethylsilyl derivatives, and there are various types of commercially available reagent for this purpose which can be used under different solvent conditions. Depending on the restrictions on the volatility of the sample, other types of treatment, such as hydrolysis and pyrolysis, may also be required, so, in addition to the GC conditions, such pretreatment must be taken fully into account. GC owes its widespread use and tremendous expansion in its scope of application to the development of liquid stationary phase materials which are very stable at high temperatures, elevated temperature analysis becoming normal practice, and to the advent of detection apparatus such as the thermal conductivity detector (TCD) and flame ionization detector (FID), which are sensitive enough to detect most chemical compounds. With regard to nitrogen, phosphorous and sulfur containing compounds, selective detection can be performed using flame photometric detectors (NPD, FPD), and an ultra-

Analytical chemistry of cosmetics 261 Table 14.2. Different types of column chromatography and their application in the analysis of cosmetics Silica gel column chromatography Elution solvent

Eluted cosmetic constituents

n-hexane

liquid paraffin, hydrocarbon waxes

Benzene

Synthetic esters Wax esters 2-ethylhexyl-p-methoxycinnamate Higher alcohols

Chloroform

Triglycerides Higher alcohols Diglycerides Fatty acids

Acetone

Fatty acids Monoglycerides Parahydroxy benzoates Ethoxylated non-ionic surfactants

Methanol

Ethoxylated non-ionic surfactants Polyethylene glycol Glycerin

; ;

Note : • Care is needed for polysiloxane and polypropylene glycol (including its copolymers with polyethylene glycol) because these constituents may be eluted in all fractions • The separation varies with the activity of the silica gel and the amount of elution solvent used. Ion e x c h a n g e chromatography Ion exchange column

Eluted fraction

Eluted cosmetic constituents

Cation exchange column

10% hydrochloric acid

Sodium chloride, triethanolamine, quarternary ammonium salts, acyl amino acids

Anion exchange column

10% acetic acid

Fatty acids, acidic esters

10% hydrochloric acid

Alkyl sulfates, alkylether sulfates Non-ionic surfactants, oils

Non-ionic fraction

Reversed phase partition chromatography Stationary phase n-heptane Silane-treated celite

: Water saturated butanol Silane-treated celite^^

Elution solvent

Eluted cosmetic constituents

50% ethanol

Ethoxylated non-ionic surfactants, polyethylene glycol

95% acetic acid

Polar oils (castor oil), higher alcohols

Chloroform

Hydrocarbons, oils, synthetic esters

Butanol saturated water

Polyethylene glycol

Ethanol

Ethoxylated non-ionic surfactants

262 New cosmetic science Table 14.3. Application of gas chromatography to the analysis of cosmetics. Substance

Substance category

Type of analysis

• Liquefied petroleum gas (LPG) • Liquid paraffin • Solid paraffin

Qualitative/compositional

• Squalane • Amine-oxides

Qualitative/quantitative Pyrolysis/qualitative/alkyl group composition

Fatty acids (derivatization required)

• • • • • •

Fatty acid Soap Fatty acid amide Glyceride Synthetic ester Natural oil/fat, wax^~^'

Qualitative/alkyl group composition Hydrolysis/qualitative/alkyl group composition Hydrolysis/qualitative/alkyl group composition Hydrolysis/qualitative/alkyl group composition Hydrolysis/qualitative/alkyl group composition Composition pattern

Higher alcohols (derivatization required)

• • • •

Higher alcohol Sulfate Synthetic ester Natural oil/fat, wax^~^^

Qualitative/alkyl group composition Hydrolysis /qualitative/alkyl group composition Hydrolysis /qualitative/alkyl group composition Hydrolysis /composition pattern

Esters (derivatization required for those with hydroxyl groups)

• Synthetic ester • Glyceride

Aliphatic amines

• Quartemary ammonium salts Pyrolysis/qualitative/alkyl group composition

Ethylene oxides Adducts (derivatization required) (up to around 10 moles)

• Higher alcohol

Polyhydric alcohols (derivatization required)

• • • • •

Solvents

Qualitative/quantitative • Water Qualitative/quantitative • Ethanol • Butyl acetate, toluene and Qualitative/quantitative/compositional other nail enamel solvents

Pharmaceutical agents and other additives

• • • . • •

Hazardous stances

. MethanoP'^ • Residual monomers • Nitrosoamines

Hydrocarbons

sub-

• Natural oil/fat, wax^°^

• Alkylphenol Propylene glycol Glycerin 1,3-butylene glycol Dipropylene glycol Polyglycerin

Menthol Camphor Saccharides Phthalate Parahydroxybenzoates Ultraviolet absorbents

Compositional/composition pattern

Qualitative/quantitative Qualitative/alkyl group composition, mono/di/tri composition Composition pattern

Alkyl group/adducted mole number composition Hydroiodic acid cleavage, alkyl group composition Alkyl group/adducted mole number composition Hydroiodic acid cleavage, alkyl group composition

Qualitative/quantitative Polymerization degree/composition

Qualitative/quantitative Derivatization/qualitative/quantitative Qualitative/quantitative Qualitative/quantitative Qualitative/quantitative Micro-quantitative Micro-quantitative Micro-quantitative (ECD)

Analytical chemistry of cosmetics 263

micro analysis^^^ of electron attracting substances, such as fragrance materials, is possible using electron capture detectors (ECD). Further, using them in combination, the clean up operation can be streamlined to a certain extent. Though the only qualitative information obtainable is retention times, this is often used to identify unknown chemical substances by the methylene unit (MU) method, in which the retention times of chemical compounds are normalized to hydrocarbon retention times^^-^^^ Further, patterning the chromatogram of thermal decomposition products by the MU method makes the qualitative analysis of polymers possible. There is also a procedure in which this is combined with the use of a FPD (NPD) in order to detect patterns characteristic of nitrogen containing polymers. 14.1.4. High performance liquid

chromatography

A greater variety of compounds can be analyzed with high performance liquid chromatography (HPLC) than with GC and, as the elements of the mobile and stationary phase are variable, HPLC has a wide range of application as a separation method. Owing to the lack of a universal detector with sufficient sensitivity and general applicability, HPLC is used mainly for quantitative analysis rather than qualitative analysis and this is shown clearly in Table 14.4 which illustrates just how wide HPLC's scope of application is. No examples of its application to fragrance materials are shown. However, there are examples of the use of the fluorimetric detector - a highly sensitive detector, details of which are described later'^^-^^^ - for this purpose and a series of FDA reports on this subject is available. Though there are different ideas on the best separation mode to use for HPLC, in view of the advances made in the development of column packing materials, their stability and flexibility in the selection of the mobile phase, reversed phase packing materials (ODS-Silica) are now very much used. In HPLC, the detection apparatus most frequently used is the ultraviolet (including visible light) detector and this is a major factor behind the increase in the use of HPLC as a quantitative analysis technique. As one of the reasons for this, selectivity can be obtained with the detector by adjusting the wavelength, which enables the sample cleanup operation to be simplified. Another reason is that most of the pretreatment procedures for HPLC analysis are simple ones; for instance just having to dissolve the sample in a suitable solvent and then filtering out insoluble substances. Furthermore, attempts have been made to use the gradient elution method for the rapid and simultaneous determination of multiple constituents. As in the case of GC, the major qualitative information obtainable from HPLC is the retention times. With the same objective in mind as the GC MU values, a study has been done on a procedure in which standard homologous series have been made from dibasic acids, gallic acid esters and alkyl phenones, and which includes the intensity ratios of 2 specific wavelengths on the UV detector (220 nm and 254 nm). Fig. 14.2 shows the chromatogram for this procedure and Table 14.5 the Retention Indices (RI) obtained for parabens, which are used as preservatives. It is highly accurate and is used as an automated identification procedure^^-^^^ Further, through the use of a multiwavelength detector (PDA), it is possible to obtain the spectra for ultraviolet and visible light absorption in addition to those for the 2 specific wavelengths, enabling this proce-

264 New cosmetic science Table 14.4. Application of high performance liquid chromatography to the analysis of cosmetics Substance category Preservatives, antimicrobial agents

Substance

Separation/detection mode

• Isopropyl methylphenoP^^ hexachlorophene • Trichlorocarbanilide^^''^^' • Zinc paraphenolsulfonate^^^ • Zinc pyrithione^^^ • Parahydroxybenzoate, salicylic acid,benzoic acid, sorbic acid, dehydroacetic acid^^^'^^* • Chlorhexidine gluconate^^^ • Benzalkonium chloride, pyridinium chloride^^^ • Resorcin^"*^ • Sulfur

Ultraviolet absorbents

Pharmaceutical agents

Forward Reversed Reversed Reversed Reversed Reversed

phase (amino)/fluorescent phase/fluorescent phase/ultraviolet phase/ion pair/ultraviolet phase/ultraviolet phase/ultraviolet

Reversed phase/ion pair/ultraviolet Reversed phase/ion pair/ultraviolet Forward phase (cyano)/ultraviolet Reversed phase/ion pair/ultraviolet Reversed phase/ultraviolet Forward phase/ultraviolet Ion chromatography/conversion to sulfate ion

• 2-hydroxy-4-methoxybenzophenone • 2-etoxyethyl-4-methoxycinnamate • 11-types ultraviolet absorbent (water or oil soluble) ^^> • 7-types ultraviolet absorbent (v^ater or oil soluble) ^'^ • 4-tert-butyl-4'-methoxydibenzoylmethane

Reversed phase/ultraviolet Reversed phase/ultraviolet Reversed phase/ion pair/ultraviolet

• Glycyrrhizinic acid salts, glycyrretinic acid^"*^

Reversed phase/ion pair/ultraviolet (anion exchange pretreatment) Reversed phase/ultraviolet (simultaneous) Reversed phase/complex/ultraviolet Forward phase/fluorescent

Reversed phase/ion pair/ultraviolet Reversed phase/ultraviolet

• Stearyl glcyrrhetinate, dl-^y-tocopherol acetate''-''^ • HinokitioP^^ • Follicle hormone^^^'^')'^^' • Thioglycolic acid, cysteine, dithiodiglycolic Reversed phase/ion pair/ultraviolet acid, cystine^'^''°>''^^ • 12 pharmaceutical agents including benzyl Reversed phase/gradient/multi-wavenicotinate and pyridoxine hydrochloride^^~^''^ length Detection (ultraviolet) Base ingredients (vehicles), etc.

• Ethoxylated glycoP^^

surfactants,

• Nonionic, anionic, amphoteric tants^^-'^' • Water soluble polymers • Xanthene colorants^^^ • Organic acid, amino acid^°' Hazardous substances

• Formaldehyde^^' • Nitrosodiethanolamine^^'

Forward phase/ultraviolet/refractive index Gel permeation/refractive index surfac- Reversed phase/refractive index

polyalkylene

Gel permeation/refractive index Reversed phase/ultraviolet Reversed phase/ultraviolet Reversed phase/post column acetylacetone reaction/visible light Forward phase/thermal energy detector (TEA)

Analytical chemistry of cosmetics

HOOC- (CH2) n-COOH

^ 1-C(CH2)nH 0

H O - ( S ) - C O O (CH^) nH

CO An : dibasic acid Gn : gallic acid ester

Cn : alkyl phenone

00 00

< <

o

o

CO

^ " ^

O

U

u

265

2o

o o o

CM

CO

-^

LO

cr>

CO

-^

LO

^

t>-

o o o 0 cj < <

UUUU!U 12

16

r-IU

20

24

mMrMvju—i 28

32

36

40

44

48

Fig. 14.2. Standard substance structures for retention indices and chromatogram. Column, Capcell Pali C18 SG (Shiseido) 4.6 mm diameter x 250 mm; carrier, (A) 0.1% phosphoric acid; (B) acetonitrile 2% -» 100% (24.5 min).

dure to be employed for identification testing on pharmaceutical agents used in cosmetics35).

There are a variety of different separation modes with HPLC and a lot of qualitative information can be obtained from the behavior of a particular substance in several of them. Among them, gel permeation chromatography (GPC), which is based on a molecular sieve mechanism, is very useful for analysis on cosmetics because molecular weight data can be obtained for polymers used in cosmetics. If GPC is used in conjuncTable 14.5. Retention indices and 2-wavelength ratios for parahydroxy benzoates and their accuracy Standard substance Methyl paraben Ethyl paraben Isopropyl paraben Propyl paraben Sec-butyl paraben Butyl paraben Hexyl paraben

RI

Standard deviation

2-wavelength ratio*

Standard deviation

8.510 10.051 10.652 10.746 11.292 11.500 13.130

0.031 0.018 0.019 0.018 0.026 0.024 0.028

1.688 1.710 1.832 1.788 1.890 1.887 1.713

0.0037 0.0098 0.0049 0.0087 0.0065 0.0088 0.0066

Measurement repeated 7 times *220 nm and 254 nm

266 New cosmetic science

tion with a refractive index (RI) detector and a low angle laser light scattering (LALLS) detector, absolute rather than relative molecular weight data may be obtained. Although the RI detector is the only truly universal one, the use of other selective detectors enables various types of quantitative analysis to be carried out easily, as mentioned previously, and in microanalysis, the electrochemical detector (ECD) and the fluorimetric detector (FLD) are used a lot. As the mobile phase is a liquid, many different types of derivatization reactions take place inside the HPLC system. The post-column derivatization method, which is designed to form derivatives from constituents which are separated and eluted from the column, is generally used for detection requiring high sensitivity and selectivity. While the formaldehyde determination procedure makes use of the acetylacetone reaction^^\ the amino acid analyzer, a specially designed apparatus, also employs post-column derivatization. Ion chromatography, which detects cations and anions rather than compounds, is used in quantitative analysis of sulfur^^^ and can also be applied to the analysis of many other inorganic ions. This technique has become possible largely through the development of the electric conductivity detector which employs an ion exchange membrane. A consideration of substance detection is thus more important with HPLC than GC. 14.1.5. X-ray

dijfractiometry

As already mentioned in the section on general separation methods, the separation of the inorganic compounds frequently used in cosmetics - such as titanium dioxide, talc, kaolin and iron oxides - from each other is extremely difficult without changing their forms and states. Analysis on inorganic compounds is thus often carried out in the unseparated state and this can be said to be a characteristic feature of analysis on the cosmetics which contain them. A typical instrument used for this purpose is the X-ray diffractiometer (XRD). It is mainly used for carrying out qualitative analysis from the diffraction peak patterns arising from the crystal structures specific to each substance but it can also be employed in quantitative analysis if necessary. In XRD analysis, the response varies depending on such factors as the sample matrix and the way the sample is packed into the sample cell. When preparing the sample for the calibration curve, it is very important to match the matrix to that of the sample as far as possible. However, it has inherent accuracy limitations in quantitative analysis and, to be on the safe side, the sensitivity should also be thought of as being at the % level. Determination of the asbestos (chrysotile) contained in talc is an example of the use of XRD for quantitative analysis^^^ Fig. 14.3 shows the XRD patterns for typical inorganic raw materials used in cosmetics. With XRD, it is difficult to do qualitative analysis on non-crystalline substances like silicic acid and phosphates which have been transformed into many different crystalline forms through pretreatment. Infrared spectrophotometry, which will be described in the next section is very effective for this purpose. An example of a qualitative analysis technique which employs X-rays to determine the elemental composition of substances, is X-ray fluorescence spectrometry (XFS). This technique has the same problem as XRD in that the inorganic raw materials used in cosmetics have many common elements (iron, aluminium, magnesium, silica, titanium, etc.), making it difficult for analysis to reflect the state of a sample. In case of quantita-

Analytical chemistry of cosmetics 267 Counts X - r a y intensity ^^^^ . ^^ ^^^ ^^^^ 5000

Kaolin' 2500

5.0 Counts X - r a y intensity 5000

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

55.0

60.0 Angle

55.0

60.0 Angle

Date : 15 Oct 1991

2500

Counts X - r a y intensity 5000

Date : 15 Oct 1991

2500

Counts

Angle

X - r a y intensity 5000

Date : 15 Oct 1991

Titanium dioxide coated mica 2500

Counts

II

10.0

5.0

X - r a y intensity 5000

15.0

A 1^ •, ••^'(VU ,^i <^^. oA c A - n 20.0

25.0

30.0

35.0

20.0

25.0

30.0

35.0

, f I • ^ l i^N,"! • . T ^ i , , 1 ' ^ 45.0 50.0 55.0 60.0 Angle

40.0

Date : 15 Oct 1991

2500 H

0 5.0

10.0

15.0

Counts X - r a y intensity 5000

, A,0.0l^, .^45.0,

50.0

l55.0\ A

60.0 Angle

Date : 15 Oct 1991

Titanium dioxide (anatase) 2500

60.0

Angle

Fig. 14.3. X-Ray diffraction patterns of typical cosmetic raw materials.

268 New cosmetic science

tive analysis, it is also affected by the sample matrix. However, rapid determination is possible with XFS if samples are pretreated using an appropriate method^^^. In view of the great difficulty in separating inorganic compounds from each other, without changing their original forms and states, and the fact that no great advances have been made in developing better separation techniques, XRD and XFS, either alone or in combination, are essential to analysis on cosmetics, and the day when they start receiving more attention is probably not far off. 14.1.6. Infrared

spectrophotometry

As infrared spectrophotometry (IR) provides information on functional groups, it has been widely used as a technique for structural analysis and structural identification on isolated substances. It has also been used as a means of deciding on the strategy for the analysis before its commencement, and has been employed in daily quality control for some time; for example as a rapid and simple method for testing raw materials when they are received. As there are many publications on the ordinary use of this technique in the identification of substances, no examples will be given here but it should be mentioned that many new applications have come about as a result of greatly enhanced sensitivity and faster analysis times through the development of Fourier Transformation, a numerical processing technique using computers, and the development of physical and chemical Fourier Transformation elements employing interferometers. It is this great increase in sensitivity that has made it possible to apply diffused reflectance (DR), attenuated total reflectance (ATR), microscopic infrared spectrophotometers (MIR) and other techniques to surface analysis, state analysis and that on samples in micro amounts. The enhanced sensitivity and reduction in analysis time has also made it possible to couple IR directly with separation techniques like GC^^\ and the interface between these apparatus has developed from a gas cell (light pipe-type) to a technique (tracer) by which it is now possible to condense and deposit GC eluates directly on sample cells. As explained later, the GC/IR combination is now being used together with GC and mass spectrometry (MS) in areas where GC/MS alone has been found unsuitable or inadequate as its use has spread; for example in analysis on saccharides and the identification of decomposition product peaks in pyrolysis GC^^-^^^. Some of these applications are given in Fig. 14.4. As the data from the Fourier Transformation process can be stored in a computer, it is easy to reanalyze it afterwards. For example, using difference spectra, it is possible to examine the state of molecules in a solution and to identify substances by retrieving spectra stored in a database. 14.1.7. Nuclear magnetic resonance Nuclear magnetic resonance (NMR) is a well known sophisticated analysis tool used in the determination of substance structures. Similar to the case of IR, since the advent of high frequency pulse Fourier transformation NMR, ^^C-NMR spectra can be obtained faster and with higher sensitivity than before. As a result, many ways of applying NMR to the analysis of cosmetics are being studied. Using ^^C-NMR will enable outline analysis carried out beforehand using IR and GC, and the determination of the analytical

Analytical chemistry of cosmetics 269 1.7

Frot 3/31/89

14 : 22

1.5h

i.oH

,

CQ

< 0.5 h 0.3 4000.0 2000.0 TYPE=A, FILE=REF , B a c k 3/31/89

uV

_U_ 1500.0 WAVENUMBERS

4000 1

1000.0 650.0 RES=0, TIME=60

14:19

Diffusion Reflectance (DR) ODS silica for liquid chromatography (Capcell Pak Ci8) Glucosamine r-*-[ Spectrum search Search result result

xJl I

ACID LACTONE MAJOK P t

IR spectrum urn of A i 1

4000.0' 2000.0 TYPE=A,FILE=REF

1500.0 WAVENUMBERS

1000.0 650.0 RES=0, TIME=60

Attenuated Total Reflectance (ATR) Laminated film-front : polyvinyl acetate back : polyethylene

UL

2500 2000 1500 HAlOOl GC(8)

1000 500

Gas Chrornatography Combined with Infrared Spectrophotometry (GC-IR) (light pipe cell) Hyaluronic acid hydrolysis product/spectrum search

Fig. 14.4 Examples of special applications of infrared spectrophotometry.

strategy, to be done more easily. Furthermore, many studies have been done on automating cosmetic analysis procedures through the use of a computer data analysis program, together with ^^C-NMR^^) Sample treatment is simple and they just have to be dissolved in a suitable deuterated solvent and the insoluble matter removed. Moreover, through the addition of internal standard substances, semi-quantitative information may be obtained. Fig. 14.5 shows the ^^C-NMR spectrum for the n-hexane extracts of a foundation and the analysis results for it showing clearly that much information can be obtained even without using any separation techniques. By enhancing the sensitivity, increasing the analysis speed and using additional special techniques (cross polarization, magic angle spinning), it is now possible to obtain NMR spectra for the solid as well as the liquid state. As we can now obtain NMR spectra for ^^Si, 3ip and others, in addition to those for ^^C and ^H, this technique can be used to examine the surfaces of inorganic powders which have been treated with silicone when used as materials for cosmetics, as well as in analysis on the states of phosphatidylcholine emulsions (liposomes), by using it in conjunction with shift reagents'^O-

270 New cosmetic science

CDCI3

AJS— 160

180

140

120

100

1IlilL 80

Chemical Shift (ppm)

TMS

®

60

40

20

(1) Dimethylpolysiloxane (2) Methylphenylpolysiloxane (3) 2-ethylhexanoate (4) Neopentylglycol di-esters (5) Fatty acid esters (6) <3'-branched alcohol esters (7) Glycerin-1-monoalkyl ethers (8) Squalane (9) n-alkyl (CH3CH2CH2CH2-) (10) Methylene chain (-(CH^)-) Fig. 14.5. ^^C-NMR Spectrum for the n-hexane extracts of a foundation.

These rather special applications to cosmetics aside, NMR is an extremely useful analysis tool for its fundamental purpose of examining structure. Making use of the various types of 2-dimensional NMR spectra, its structural analysis capabilities will be very important to the development of new materials for cosmetics from now on. 14.1.8. Mass

spectrometry

Mass spectrometry (MS) is another useful tool for structural analysis because of the molecular weight data it provides. However, in analysis on cosmetics, it is normally used in conjunction with GC rather than by itself. Though the development of interfaces (jet separators) and their enhancement of stability has helped increase the use of the GC/MS combination, limitations are imposed by the GC part of the setup, particularly by the volatility of substances to be analyzed. Furthermore, in view of the fact that Electron Impact (EI) and Chemical Ionization (CI) are the types of ionization most used, the most important molecular weight information may not always be obtained. To solve this problem, it would be necessary to introduce another effective separation technique, i.e. HPLC, into the system, so a response to the need to develop universal detectors for HPLC is considered to be of great importance. For cosmetics, the importance the HPLC/MS combination is very apparent because they contain such large proportions of non-volatile substances. For ways of obtaining mass spectra for non-volatile substances, attention is being focused on such techniques as Fast Atom Bombardment Ionization (FAB), Atmospheric Pressure Ionization (API) and Thermo-spray Ionization (TSI). They are also being

Analytical chemistry of cosmetics

UV detector (210nm) Pantothenylethyl ether (200ng)

Mass chromatography using a molecular ion 80 60 40 20

m/z :

* E + 06 2.202

234

Total ion chromatogram (160 — 1000) %ioo RIC 80 60 40 20 0

2:00

4:00

6:00

* E + 07 1.207

8:00

10:00

12:00

CH. CH3CH2O CH2CH2CH2NH

COCHCCH2OH OH

CH3

CnH2304N

=

233

'*E + 06

100

150

•

• 200

250

300

Fig. 14.6 HPLC/FABMS analysis on pantothenylethyl ether used in hair growth promoter.

271

272

New cosmetic science

looked at as interfaces for HPLI. Moreover, it has been reported that the FAB/MS combination provides optimum conditions for measuring the very small amounts of the various additives that cosmetics contain'^^-^^) It can be seen from Fig. 14.6 that a mass chromatogram enables this system to be used as a general purpose or highly selective detector. However, in order to use it as a universal detector for unidentified compounds, such factors as background processing still have to be looked at and there are still many problems to be solved if the level of a Total Ion Counter (TIC) is to be attained with the GC/MS system. Recently, a MS/MS system combining 2 mass spectrometers has become available for structural analysis work and future applications are now being looked at (not discussed here). 14.1.9. Atomic emission spectrophotometry, spectrophotometry

atomic absorption

Atomic Emission Spectrophotometry (AES) and Atomic Absorption Spectrophotometry (AAS) are used for micro-quantitative analysis and are widely applied in cosmetics as a rapid determination method for lead, arsenic and heavy metals. There is a great tendency to use the latter because it is particularly suited to quantitative analysis; however, since it is sensitive to the sample matrices, various pretreatment methods have been investigated and its use as a rapid determination method for lead has been studied'^'^^^^ In addition to quantitative analysis, AES can be used simultaneously as a qualitative analysis technique for metallic elements and it is employed as a non-separation analysis technique for inorganic compounds used in cosmetics. Inductively coupled plasma (ICP) AES provides extremely high sensitivity even though solutions have to be made from the sample. The method of using it is decided in consideration of the information desired and the time taken. However, the conventional AES method of using an arc to excite atoms will continue to be used because samples can be analyzed by just inserting them into the carbon rods without any prior treatment. 14.1.10. Summary of analysis on cosmetics In the foregoing, we have described various analytical techniques and how they are used in the analysis of cosmetics and their raw materials. Including official ones, a great many procedures have been established for identifying the major ingredients of raw materials and cosmetic products, and for determining the amounts of ingredients in cosmetics. Although there should have been a section on thin layer chromatography because it is now a very general analytical procedure, information on thin layer chromatography has been limited to a publication in the references on its use in analysis on colors^^^ Progress made in the analysis of cosmetics owes much to advances made in the analytical techniques of HPLC, IR, GC/MS and NMR, and their increasing use. However, as regards their utilization, there is a need for a complete change in our way of thinking, and now that high sensitivity analysis, rapid analysis and computer processing of analysis results are easy to do, with respect to the object of the analysis, there is a need to progress from that focusing on raw materials and products, and checking the amounts of ingredients in cosmetics, to a type of analysis linked to upgrading quality assurance and

Analytical chemistry of cosmetics

273

technology development. In this sense, analysis will surely become more micro in nature and there will be ever increasing needs for structural determinations on unknown compounds. In pace with this, new analytical techniques will of course have to be developed, in particular new separation techniques such as super critical fluid chromatography, super critical fluid extraction, capillary zone electrophoresis (CZE) and ways of employing HPLC as a preparatory procedure. There will soon also be a need for further developments in general separation techniques like desalting, and ones with high separation capabilities like countercurrent distribution which will enable larger volumes of samples to be handled. Though there have been very few studies on the use of CZE in analysis on cosmetics, its application to analysis on preservatives has been studied^^^ Such technologies should provide the impetus for analytical chemistry in the cosmetics industry to develop from a tool just used for quality assurance, into one used in product development as well, and looking at analysis in essence, the task for the future will be the interfacing of such sophisticated analytical techniques. Regarding their purpose, state, surface state and morphological analysis are already very important, and scanning electron microscope, transmission electron microscope, differential scanning calorimetry and thermal gravimetric analyses are now in very widespread use.

14.2. Analysis of skin and hair It has already been mentioned in this chapter that the use of analytical chemistry in cosmetics is not limited to the analysis of cosmetic products so, as an example bearing this out, something will now be said about how it is used in basic research on the skin and hair to which cosmetics are applied. As the results of analysis on skin and hair have already been given in their detailed descriptions at the beginning of this book, in this section, the techniques used for such analysis have been focused on. In cosmetics research, there is a great need for bio-related analysis and in addition to biochemical analysis, instrumental analysis is becoming more and more necessary all the time. 14.2.1. Analysis of skin In analysis on skin, in particular human skin, an absolute condition for the techniques

Extraction solvent-lOml Sebum (acetone) Amino acids (distilled water) Polar lipids (ethanol)

L-

Arm

\

Fig. 14.7. Cup for extracting skin constituents.

274 New cosmetic science

Squalane Fatty acid

Cholesterol ester Triglyceride

Fig. 14.8 Gas chromatogram for sebum. Column, Diasolid ZT; temperature, 100-350°C, l-°C/min rise; extraction and methylation.

used is that they be non-invasive. A glass cup, like the one shown in Fig. 14.7, is put on the skin and then filled with a solvent suited to the substances to be analyzed and left on for a given time. This is the normal procedure for extracting the various substances in the skin and those that are secreted on its surface. Another procedure involves samples which can be obtained with little or no damage to the skin, for example skin which peels off after sunburn and horny layer removed from the heel. It is extremely difficult to dissolve the horny layer and even if it can be dissolved it is difficult to do so without destroying the substances present in it. The normal way of doing this is thus by reflux extraction of the substances dissolved in the solvent and it has been found that, if the solvent is combined with a surfactant in an appropriate manner, a dispersion of the horny layer can be made right down to the cellular leveP3\ This is a useful technique for doing analysis on substances which are difficult to extract using a solvent. Analysis of skin surface lipids is a typical analysis procedure performed on the skin. GC or the GC/MS combination is used for this purpose^^). Fig. 14.8 shows an example of analysis on so-called neutral lipids like fatty acids, squalane, cholesterol, wax esters, and glycerides. This procedure is also used for analysis of ceramides and other polar lipids. In the case of ceramides, the HPLC/MS (TSP) combination is also used to determine molecular weights^^\ Analysis may be done on amino acids which are extracted in wal^^j.55-56) Another example of skin-related analysis is on the status of water in the skin and this has been closely investigated using near-infrared spectrometry, in particular how it is bonded with the skin^^'^^). A particular example of analysis on the skin is the identification of substances causing foot odor, on which studies have been carried out^^-^^>. Substances secreted into the socks were extracted and analyzed using a Headspace GC in order to determine the substances which cause foot odor. A chromatogram for this is shown in Fig. 14.9.

Analytical chemistry of cosmetics

275

1 Foot odor (iso-C5)

(C9) (CIO)

1

(C8)

LJJUl^.^"^LJluu h (C6) 1

100

200

300

m

-J

500 0

100

200

300

400

Fig. 14.9. GC/HS chromatogram for foot odor constituents (acidic constituents).

This technique can also be used in the analysis of axillary odor. In this case, samples of the substances secreted are collected in a piece of cotton wool held in the axilla. This analysis procedure has also been used to elucidate the mechanism by which sweat inhibitors like zinc oxide and aluminum hydroxy chloride suppress body odor, as well as in the assessment of their efficacy^^-^^^ thereby playing an important role in research and development. Another particular example is the investigation of percutaneous absorption involving the use of photoacoustic spectrometry (PAS). Although this cannot be said to be the analysis of the skin itself, it is very important to cosmetics. PAS is a highly sensitive technique and is used in a variety of ways because it can analyze the condition of the skin surface as it is. It is based on the principle that percutaneous absorption can be observed by measuring the continually changing amounts of residual substances on the skin surface^^^^\ Fig. 14.10 shows a schematic diagram of the apparatus used and an example of the results obtained. One can clearly see the correspondence between the decrease in the amount of substance (indometacin) on the skin surface and the amount of substance absorbed, i.e. the amount of substance passing through the skin membrane. Although this technique is limited in that it can only be used with visible lasers or specific wavelength UV lasers, it can be used as a technique for analyzing micro quantities of substances on surfaces other than the skin, so it deserves more attention as an analytical technique for general use. The previously mentioned cup method has also been used to analyze to what extent cosmetics applied to the skin remain in it and on its surface. The task for the present is to see how instrumental analysis can be applied to high molecular weight substances, i.e. proteins and enzymes. Though a variety of studies have been done on the relationship between elution behavior and separation behavior, and column packings in HPLC^^-^^> and new packing materials are being developed, it should be mentioned again that one of the problems remaining to be solved is how to interface them with identification instruments.

276

New cosmetic

science

-*

PAS signal Microphone Open-ended PAS cell

Optical fiber PAS measurement

Indometacin ointment JCTransmitted photocell

Laser (incident light) Absorbance measurement

Rotator

""Solvent (quartz) Vertical diffusion cell (cell volume : 4.5ml)

Magnetic stirrer

Model drug : 1% indometacin ointment (base : PEG) ' Amount applied ! 10mg/5mm(^ • Membrane : HR-1 skin (fern. 10 wks. old) • Solvent : physiological saline

80

^

3.0

60

Amount passing through skin : 1.1%

PAS

2.0

g

'Tn

CO

<

••

•

•••

1.0 -e

Absorbance

20 A

^

A

A A

A

A A

A

A

A

. A ^ A

A

^ A " A

A

4

A

6

A A

. A^

A A

AA

o

A

<

A

10

Time (hrs) Fig. 14.10. Apparatus for measuring percutaneous absorption by PAS and results of iVi vitro test using it.

14.2,2, Analysis of hair For hair, it is easier to obtain analysis samples non-invasively than for skin. However, as the physical state of hair has been given the main emphasis, fewer studies have been done on the analysis of its chemical composition than for skin. In the same way as for skin, lipid analysis is done by extraction with a solvent but the analysis of the lipids in the hair structure is done after enzymatic digestion or breaking the cystine bonds with reducing agents used in permanent waving lotions. This type of

Analytical chemistry of cosmetics 277 Peak deconvolution

Alkaline hair color

Neutral , hair color

28.1059

S

19.9510 h

J2

<

11.7962 1200

1100

1000

Wave Numbers

1100

1000

900

Wave Numbers

Fig. 14.11. Hair IR spectra (measurement of hair oxidation by micro tablet method).

analysis is not limited to lipids; it is also extends to amino acid composition and metals that are present in micro amounts. The techniques used are virtually the same as those for skin but more attention needs to be paid to the extraction of the substances contained in hair. Many physical testing methods are now used to assess damage to the hair and high sensitivity IR is sometimes employed for this purpose, in addition to the procedures described above for detecting compositional changes. In Fig. 14.11, IR spectra are used to show the progressive state of oxidation of the mercapto groups in hair. This type of analysis has been made possible through the ability to obtain IR spectra for samples in micro amounts and to carry out computer deconvolution on the spectra.

14.3. Automation of analysis With the increasing diversification of cosmetic products and the changeover to large variety small lot production, there is now a tendency in quality control towards a greater frequency and greater variety of testing, and the results are required in ever shorter times. For this reason, the automation of analysis is of great importance to the cosmetics industry. Moreover, although studies have been done on incorporating advanced instrumental analysis techniques for raising the quality of, and simplifying and rationalizing the various analyses and testing stipulated in cosmetics-related regulations, and those conducted in the course of quality assurance have been investigated, cosmetics manufacturers themselves will also have to make efforts towards automating analysis. This

278 New cosmetic science

means that they will have to make it a first priority to create automatic, night operation systems incorporating such commonplace equipment as autosamplers and integrators and robots, which have recently come on the scene for simple pretreatment of samples, in order to carry out everyday testing with high accuracy and speed. In addition to the initial results report form attached to the analysis, it has become a necessity to re-input data from the analytical instruments for the immediate preparation of data in the required reporting format, and improvements will also be required in this respect. It will also be very important to make databases from analysis results, to enable large quantities of data to be studied from various angles and to make it widely available.

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38.

Ikeda, T., ed.: Cosmetic Science, 13th. edn., p. 106, Nanzando, 1978. Ishiwata, K.: Textbook for 7th. Introductory Course on Analysis of Color Materials, p. 75, 1991. Analysis and testing of cosmetics and assessment of their functions and efficacy. Fragrance J., Suppl. edn., 5 (1984). Jpn. Anal. Chem. Soc, ed.: Analytical Chemistry Handbook, 4th. edn., p. 1101,1988. Nakamura, K., Matsumoto, I.: J. Jpn. Oil Chemists Soc, 26 (8), 464 (1977). Matsumoto, I., Ohta, T., Takamatsu, T., Nakano, M.: J. Chem. Soc. Jpn., 951 (1972). Takamatsu, T., Ohta, T., Matsumoto, I.: J. Chem. Soc. Jpn., 2378 (1973). Fukuda, Y., Takamatsu, T., Matsumoto, I.: Jpn. Chem. Soc, 32nd. Annual Spring Meeting Abstracts III, 1779 (1975). Matsumoto, I., Takamatsu, T., Ohta, T.: J. Chem. Soc. Jpn., 635 (1972). Ohta, T., Nanba, R., Matsumoto, I.: J. Chem. Soc Jpn., 1862 (1976). Matsumoto, I., Yoneyama, H., Tanaka, K.: Jpn. J. Toxicol. Environmental Health, 17, 384 (1971). Nanba, R., Shibamoto, A., Nishiya, H., Morikawa, Y., Tahara, S., Mitsui, T.: J. Soc Cosmet. Chem. Jpn., 17 (1), 35 (1983). Japan Pharmaceutical Association, ed.: Standard Methods of Analysis for Hygienic Chemists - With Commentary, p. 843, Kanahara Shuppan, 1990. Japan Cosmetic Industry Association, ed.: Text for 10th. Cosmetics Technology Conference, p. 167, 1991. Japan Cosmetics Industry Association, ed.: Text for 12th. Cosmetics Technology Conference, p. 179, 1989. Nakamura, K., Morikawa, Y.: Bunseki Kagaku, 34 (4), 224 (1983). Ohba, M., Nakamura, K., Matsuoka, M.: J. Pharmaceutical Soc. Jpn., 111 (9), 542 (1991). Hanafusa, P., Nakamura, K., Togano, S., Ohta, T.: Bunseki Kagaku, 38 (3), 124 (1989). Eda, H., Nakamura, K., Matsumoto, I.: Jpn. J. Toxicol. Environmental Health, 24, 260 (1978). Fukuda, Y., Nakamura, F., Morikawa, Y.: Jpn. J. Toxicol. Environmental Health, 31 (3), 209 (1985). Koyama, J., Matsumoto, I., Ohtsu, Y., Nakada, O.: Bunseki Kagaku, 37 (3), 142 (1988). Yamamoto, S., Kanda, M., Yokouchi, M., Tahara, S.: J. Chromatogr., 370, 179 (1986). Yamamoto, S., Kanda, M., Yokouchi, M., Tahara, S.: J. Chromatogr., 396, 404 (1987). Yamamoto, S., Nakamura, K., Morikawa, Y.: J. Liquid Chromatogr., 7 (5), 1033 (1984). Nakamura, K., Matsumoto, I.: J. Chem. .Soc Jpn., 1342 (1975). Nakamura, K., Morikawa, Y., Matsumoto, I.: J. Am. Oil Chem. Soc, 58 (1), 72 (1981). Nakamura, K., Morikawa, Y.: J. Am. Oil Chem. Soc, 61 (6), 1130 (1984). Nakamura, K., Morikawa, Y., Matsumoto, I.: J. Jpn. Oil Chem. Soc, 29 (7), 501 (1980). Ohtsu, Y., Matsumoto, I.: J. Chem. Soc. Jpn., 511 (1979). Nakamura, K., Morikawa, Y., Matsumoto, I.: Bunseki Kagaku, 29 (5), 314 (1980). Kijima, K. et al:. Japan Pharmaceutical Association 112th. Annual Meeting Abstracts, 4, 236 (1992). Fukuda, Y., Morikawa, Y., Matsumoto, I.: Anal. Chem., 53 (13), 2001 (1981). Hirose, N., Nanba, R., Matsuoka, M.: Report of the 116th. Committee on Chemistry Creating Organic Compounds with Novel Functions, Jpn. Soc Promotion Sci., 3 (1991). Nanba, R., Ishiwata, K., Komatsu, K., Matsuoka, M.: 1st Chromatography Science Conference, 1990. Yamamoto, S., Hosaka, M., Kanda, M., Yokouchi, M., Yamada, J., Tahara, T.: Bunseki Kagaku, 36, T 108 (1987). Japan Cosmetics Industry Association, ed.: Text for 8th. Cosmetics Technology Conference, p. 84, 1987. Komatsu, K., Ishiwata, K., Matsumoto, I.: J. Soc. Cosmet. Chem. Jpn., 12 (2), 10 (1978). Ferraro, J. R., Krishnan, K.: Practical Fourier Transform Infrared Spectroscopy, p. 470, Academic Press, 1989.

Analytical chemistry of cosmetics 279 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79.

Nanba, R., Kadowaki, E., Nakada, O.: Report of the 116th. Committee on Chemistry Creating Organic Compounds with Novel Functions, Jpn. Soc. Promotion Sci., (1985). Kadowaki, E., Nanba, R., Nakada, K.: Jpn. Chem. Assoc, 50th. Annual Spring Meeting Abstracts I, p. 609 (1985). Lichtenberg, D., Amselem, S., Tamir, I.: Biochemistry, 18 (19), 4169 (1979). Yoshida, S., Nanba, R., Takamatsu, T., Matsuoka, M.: International Congress on Analytical Chemistry Abstracts, p. 192, Chiba, Japan, 1991. Yoshida, S., Nanba, R., Takamatsu, T., Matsuoka, M.: HPLC '92 Abstracts, p. A-70, 1992. Matsumoto, I., Takabayashi, T., Nakamura, I.: Bunseki Kagaku, 19, 771 (1970). Matsumoto, I., Okamoto, M., Kanda, M.: Bunseki Kagaku, 20, 287 (1971). Matsumoto, I., Kanda, M., Ishiwata, K.: Jpn. Pharmaceutical Assoc, 92nd. Annual Spring Meeting Abstracts III, p. 216(1972). Kanda, M., Hori, Y., Matsumoto, I.: Bunseki Kagaku, 24, 299 (1975). Yagita, Y., Tanaka, K., Sekiguchi, T., Kanda, M., Matsumoto, I.: Jpn. J. Toxicol. Environmental Health, 21, 225 (1975). Okamoto, M., Kanda, M., Matsumoto, I., Miya, Y.: J. Soc. Cosmet. Chem., 22, 589 (1971). Hayashi, K., Koyama, K., Kobayashi, N., Kano, C : J. Soc. Cosmet. Chem. Jpn., 9, 62 (1975). Matsumoto, I., Takashiba, K., Honma, Y.: Jpn. J. Toxicol. Environmental Health, 19 (4), 278 (1972). Dai, T., Nakamura, I., Kubo, S., Matsuoka, M.: Jpn. J. Toxicol. Environmental Health, 33 (4), 271 (1987). Takahashi, M., Aizawa, M., Miyazawa, K., Machida, Y.: J. Soc Cosmet. Chem., 38, 21 (1987). Denda, M., Hori, J., Koyama, J., Yoshida, S., Nanba, R., Takahashi, M., Horii, I.: Arch. Dermatol. Res., 284, 363 (1992). Koyama, J., Morikawa, Y., Matsumoto, I.: J. Soc. Cosmet. Chem. Jpn., 15 (1), 45 (1981). Koyama, J., Horii, I., Kawasaki, K., Nakayama, Y.: J. Soc. Cosmet. Chem., 35, 185 (1984). Kanda, F., Yagi, E., Fukuda, M., Nakajima, K., Ohta, T., Nakata, O.: Br. J. Dermatol., 122, 771 (1990). Kanda, F., Yagi, E., Fukuda, M., Nakajima, K., Ohta, T., Nakata, O.: J. Soc. Cosmet. Chem., 40, 335 (1989). Kanda, F., Nakane, T., Matsuoka, M., Tomita, K.: J. Soc. Cosmet. Chem., 41, 197 (1990). Takamoto, R., Nanba, R., Matsuoka, M., Sawada, T.: Anal. Chem., 64 (21), 2661 (1992). Takamoto, R., Nanba, R., Nakata, O., Sawada, T.: Anal. Chem., 62 (7), 674 (1990). Takamoto, R., Nanba, R., Takamatsu, T., Matsuoka, M., Sawada, T.: International Congress on Analytical Chemistry Abstracts, p. 522, Chiba, Japan, 1991. Koyama, J., Nomura, J., Ohtsu, Y., Nakata, O., Takahashi, M.: Chem. Lett., 687 (1990). Koyama, J., Kanda, T., Ohtsu, Y., Nakamura, K., Fukui, H., Nakata, K.: J. Chem. Soc Jpn., 1, 45 (1989). Senzel, A. J.: Newburger's Manual of Cosmetic Analysis 2nd. edn.. Association of Official Analytical Chemists Inc., 1977. Butler, H., Rigano, L., Takamatsu, T.: Cosmetic Raw Material Analysis, International Federation of Societies of Cosmetics Chemists, Micelle Press, UK, 1994. Nikitakis, J. M.: CTFA Specification, Cosmetic, Toiletry and Fragrance Associations Inc., 1990. Kleinert, B.: Seifen, Oele, Fette, Wachse, 114 (20), 845 (1988). Bore, P.: Cosmetic Science and Technology Series, Vol. 4, Cosmetic Analysis, p. 534, Marcel Dekker, 1985. Rieger, M. M., ed.: Surfactant in Cosmetics (Surfactant Science Series Vol. 16), 103, Marcel Dekker, 1985. Yates, L. R., Wenninger, J. A.: J. Assoc. Off Anal. Chem., 71 (5), 965 (1988). Wisneski, H. H., Yates, R. L., Wenninger, J. A.: J. Assoc. Off Anal. Chem., 71 (4), 821 (1988). Wisneski, H. H., Yates, R. L., Wenninger, J. A.: J. Assoc Off Anal. Chem., 71 (4), 818 (1988). Demers, F. X., Yates, R. L., Davis, H. M.: J. Assoc. Off Anal. Chem., 70 (6), 958 (1987). Wisneski, H. H. et al.: J. Assoc. Off Anal. Chem., 77 (6), 1467 (1994). Tokuda, H. et al.: J. Chromatogr., 454, 109 (1988). Maier, F.: Seifen, Oele, Fette, Wachse, 119 (16), 991 (1993). Martin, K. A.: Appl. Spectrosc. Rev., 27 (4), 325 (1992). Martin, K. A.: IFSCC Congress Preprints, B 102, p. 167, 1994.

15 Cosmetic manufacturing equipment Cosmetic products (including quasi drugs) come in a tremendous variety of different forms; there is also a great variation in their color and smell. For this reason, manufacturing equipment, production processes and other technologies are actively developing at a pace with research on cosmetic products to ensure that the best quality products are produced. During the manufacture of cosmetics, everything from the weighing of raw materials to the packaging and cartoning of the finished product must be done under the cleanest conditions avoiding contamination from the outside as well that from the internal parts of manufacturing equipment. In addition, for certain products, efforts are now being made to put the overall manufacturing process under computer control and save on energy and manpower through the introduction of factory automation. In order to ensure the quality of cosmetic products, many countries have introduced their own Good Manufacturing Practice (GMP)i) based on that for pharmaceutical products. In Japan, the Japan Cosmetic Industry Association has drawn up its own quality standard^) while in the USA, CFTA is advising the cosmetics industry on quality assurance in accordance with the FDA guidelines. In Europe, a unified standard based on COLIPA guidelines is about to be established. The manufacturing equipment for cosmetics can be broadly divided into product manufacturing equipment and molding, filling and packaging equipment. Product manufacturing equipment comprises such items as grinders and dispersing equipment for powders and other ingredients used in the manufacture of makeup cosmetics and the emulsifying and cooling equipment used for creams, milky lotions, etc.; molding equipment comprises automatic molding machines for lipsticks and other stick form products, press molding machines for foundations, eye color, etc. and other such equipment (Table 15.1). Table 15.1. Typical equipment for manufacturing cosmetics Equipment

Milky lotions/creams

Lotions

Powder compacts

Lipsticks

Mixers

O

O

O

O

Grinders

O

Dispersing, emulsifying equipment

O

o

Cooling equipment

o

o o o

Molding equipment Filling equipment

o

o 280

o o

Cosmetic manufacturing equipment 281 Table 15.2 Different types of grinders Grinding force a. Compression

b. Impact compression

Grinder mechanism

Break, Dodge, Single Toggle J-crusher Gyratorycorn Crusher, Hydrocone Crusher Roll, Single Roll, Disk Crusher

i . Grain mortar ii. Hammer

Stamp Mill Hammer Mill, Impeller Breaker, Impact Crusher, Raymond Vertical Mill, Disintegrator, Dismembrator Z-mill, Z-pulverizer, Micronizer, Reductionizer, Spraying Grinder, Air Mill Ball Mill, Tube Mill, Rod Mill, Conical, Tricon Mill, Hildebrande Mill

iii. Hydraulic energy iv. Revolving cylinder

c. Shearing

Rotatory i . Rotatory

d. Friction

Grinder names

i . Biting crusher ii. Gyratory iii. Rotatory

ii. Gyratory iii. Centrifugal iv. Rotating cylinder

Cutting Mill, Rotary Crusher, Shearing Roll Mill Stone Mill, Pan Mill, Attrition Mill, Edge Runner, Sand Grinder Screw Crusher, Column Crusher, Roller Mill type (Huntington, Raymond, Griffin), Ball Mill type (Roulette, Fuller Mill) Ring Roll Mill (Kent, Stateband Mill), High Speed Ball Mill, Low Speed Ball Mill, High Swing Ball Mill

(Kubo, Mizuwatari et al : Powder Theory and Applications, Maruzen, 1962)

This chapter describes the major types of equipment in use.

15.1. Grinders Grinders can be divided into wet grinders, dry grinders, continuous grinders, batch grinders and those for coarse and fine grinding. Some of the dispersing machines described in Section 15.3 can be used as wet grinders. In this section, the dry grinder is described. In Table 15.2, grinders are classified according to how they deliver the grinding power. As many of the powders used in cosmetics are already in fine powder form, the main purpose of using grinders is not usually grinding; they are more often used to make the mixing process faster by breaking up powder lumps. This is done because heat produced in the mixing process may cause degradation of organic ingredients, the mechano-chemical effect may produce a change in particle surface properties and in the worst case, there may be alteration of the crystal structure or other internal changes^).

15.2. Powder mixing equipment The grinding devices described in the previous section are also often used as mixing

282

New cosmetic

science Raw materials in

Raw materials in / Bearing

Sprocket

Fig. 15.1. V-type mixer.

equipment. Powders can be mixed wet or dry. Here, we discuss the dry method of mixing, confining this to equipment used solely for the mixing of powders. Mixing equipment can be broadly divided into the rotatory type and the fixed type. With the rotatory type, it is the container that rotates and the different types that have been designed include a tubular type, a double cone type, a cube-shaped type, a pyramid type and a V-type. With the fixed type, the container is fixed and a screw, ribbon or other type stirring apparatus revolves inside it. This equipment is used when a color or perfume is sprayed into powder form cosmetics as well as for carrying out the preliminary mixing of powders. Fig. 15.1 shows the construction of the V-type mixer, a typical rotatory mixing device, and Fig. 15.2 that of the conical screw mixer, a typical fixed mixing device.

Raw materials in

Motor

Screw blade

Emptying handle

Mixture out Fig. 15.2. Conical screw mixer.

Cosmetic manufacturing equipment 283

.Motor

uJ Dispersion unit

Blade arrangement on mixing head Fig. 15.3. Disper.

15.3. Dispersion and emulsification equipment The following are examples of dispersion and emulsification equipmenf^^ 15.3.1. Propeller mixer In the propeller mixer, a propeller is attached to the end of rod which rotates. It is only used for the preliminary dispersion and emulsification because it does not have much dispersing capability. 15.3.2.

Disper

The mechanism of the disper consists of a mixing head with turbine-type blades attached

Flow reversing plate upper and lower rods Motor Screw^ for fixing Coupl Stator Flow reversing plate

Stator

Turbine

Shaft

Cross section of mixing head -Bottom plate -Supporting base

Fig. 15.4. Schematic diagram of a homomixer.

284

New cosmetic science

Insert preliminary emulsion and subject to high pressure

Emulsion out

Bearing packing

Handle with screws

Load spring

Fig. 15.5. Schematic diagram of a homogenizer.

to the end of a rod which rotates at high speed. It has higher dispersing capability than the propeller mixer (Fig. 15.3). 15.3.3.

Homomixer

This type of mixer is also called an Appenbach mixer. The homomixer's mechanism consists of a mixing head and turbine-type blades in a cylindrical container. It is designed so that convection currents are produced in the container, in order to produce very fine, uniform emulsion particles (Fig. 15.4). 15.3.4.

Homogenizer

The homogenizer is a very powerful continuous emulsification device which sprays materials out of a small aperture under high pressure (Fig. 15.5). Insert preliminary emulsion

Shaft packing and bearing "Connection to motor

Fig. 15.6. Schematic diagram of a colloid mill.

Cosmetic manufacturing equipment 285

15.3.5. Colloid mill The material is passed through the narrow spaces between the 2 sintered components of the mill, one of them fixed the other rotating at high speed (Fig. 15.6). 15.3.6. Pebble mill The material is put into the mixing drum together with hard pebbles of about 10 mm in diameter and this is mixed by a powerful mixing device. Grinding together with the pebbles causes dispersion to take place. This equipment is suitable for the dispersion of powders. 15.3.7. Ultrasonic

emulsifier

There are two types: in one of them the material is bombarded with ultrasonic waves and the other has a tube equipped with vibrating blades which generate ultrasonic waves when the material is poured into it.

15.4. Kneading equipment Kneading equipment^^ is used in the manufacture of cosmetics having low fluidity on account of the large amounts of powders that they contain. 15.4.1.

Kneader

The kneader is a powerful ribbon-type mixer. As it can be connected to vacuum deairing equipment, the kneader is very good for the manufacture of highly viscous cosmetics in which bubbles easily form. 15.4.2.

Roller

The roller has been in use for a very long time. It is a very powerful kneading device. This equipment has either 2 or 3 rollers. It is suitable for lipsticks, enamels and other cosmetics in which color matching is important. 15.4.3. Gyratory grinder This equipment is suitable for grinding and breaking up powder lumps, and wetting them in stages at the same time in order to achieve dilution.

15.5. Cooling equipment The following describes the equipment used in the cooling of milky lotions, creams and other cosmetics and the methods by which cooling is achieved.

286

New cosmetic science

Tachometer

Dust collection

Agitator

I4I Speed change handle

Homoblade

Anchor blade Fig. 15.7. Schematic diagram of an emulsification device customized for cooling purposes (combimix).

15.5.1. Cooling equipment employing stirring Cosmetics are stirred to enhance the effect of cooling the container from outside and ensure that cooling is uniform. This equipment is used for systems containing a lot of soaps and other emulsifiers whose properties would change if the temperature dropped rapidly and in the case that various substances are added and dispersed through the material during the cooling process. In the equipment shown in Fig. 15.7, the material is cooled by passing cooling water between the walls of the double-wall vessel and stirring it with the paddle-type stirring device inside the vessel. Usually a combination of a Homomixer and Disper is installed inside the vessel. This equipment is used in the manufacture of emulsion products for which vacuum de-airing is carried out. 15.5.2. Cooling equipment employing heat exchange Heat exchangers are now much used for the continuous and rapid cooling of emulsion systems formed at high temperature. 15.5.2.1. Plate heat exchanger Several layers of heat exchange plates are installed closely spaced and the emulsion system and refrigerant are passed through them in opposing directions (Fig. 15.8). The heat exchange between the hot emulsion and the refrigerant takes place at the interface formed by the plates cooling the emulsion. As the space that the emulsion flows through is very narrow, this equipment is suitable for the rapid cooling of low viscosity milky lotions; it is difficult to cool higher viscosity emulsions using it.

Cosmetic

manufacturing

equipment

Inlet valve Pressure gauge Inlet

^

tfer

^

a. External View Hot emulsion Refrigerant

im

Refrigerant

in if M I

I •

I •

cold emulsion

rx

•n"

b. Internal Structure

Fig. 15.8. Plate heat exchanger.

Hot emulsion Hot emulsion pump Inlet temperature gauge

¥

Refrigerant inlet

^

lloUoL,A,J^_^L_A,,A-,^,-^J^,_Rje^jq_J^^^

Refrigerant outlet Outlet valve

Fig. 15.9. Scrapered surface heat exchanger.

287

288

New cosmetic science

15.5.2.2. Scrapered surface heat exchanger The external wall of the scrapered surface heat exchanger cylinder is cooled by the refrigerant and the emulsion is pumped through it to be cooled through heat exchange when it comes into contact with the cylinder. Rapid cooling is achieved by pumping the emulsion through the cylinder and stirring it at the same time (Fig. 15.9). Emulsion which adheres to the cylinder is scraped and mixed. This equipment is widely used for high viscosity milky lotions and creams.

15.6. Molding machines Lipsticks, foundations and eye shadows are molded into shape before pressing into the final product container. The following describes machines for molding lipsticks and compact foundations - typical examples of this type of equipment. 15.6.1. Lipstick molding machines There are several types of lipstick molding machine. Broadly dividing them according to the different types of mold, we have the conventional metal mold molding machines and the recently developed automatic molding machines using ogive capsules. 15.6.1.1. Metal mold molding machines With this type of machine, molten lipstick is poured into a split metal mold and after cooling, the mold is split vertically and the lipstick released from it. The molds are made from metals with excellent thermal conduction and the machines are designed so that the molding temperature can be easily controlled, as well as for shortness of molding time. Such intricate operations as applying mold lubricant to the inside surfaces of the mold, removing the overfilling and cleaning molds have to be done manually. Once removed < Preheat >

< Reheat/cool lower part < Final cooling >

1 \JJ

kf

[Fill

\ \ Hot blast \ "^

^

"c5 11

—

u

7T,

UT7

tt )tbl ast 1

[J-^givtL] [m

I Pinhole prevention!

y "" Ak

y

1w

^

W tt [Cold blast 1

-«•-

w

w

\

[Col dbl ast|

[Contraction hole prevention | [Easing mold release] Fig. 15.10. EJ molding method.

u

Cosmetic manufacturing equipment 289

Fig. 15.11. Automatic lipstick molding machine (Yoshino Kogyosho Co., Ltd.).

the molded lipstick is inserted into the container and flaming is carried out to bring out its luster. 15.6.1.2. Ogive capsule molding machines This type of equipment was developed as an automatic molding machine. In its molding process, the molten lipstick is poured into an ogive made from a resin or a casing known as a capsule. The best known molding method is the Ejectlet (EJ) method developed by the British company Ejectlet. It is shown diagrammatically in Fig. 15.10. The molding machine has several holders mounted on its chain conveyor into which the containers are put inverted and the chain conveyor operates intermittently to move the containers through each stage of the molding process. This method enables the molding of lipstick to be automated and can be used for its mass production. However, the temperature and time conditions for each molding process must be set very accurately to suit different lipstick formulae and actually have a great influence on lipstick moldability. Fig. 15.11 is a photograph of this type of automatic molding machine. 15.6.2. Foundation molding machines Nowadays, most powder cosmetics are molded using automatic pressing machines. These are turntable-type machines in which metal dishes are fed automatically to the press concave mold attached to a rotating disc by the parts feeder. The dish is then rotated to the next position at which a fixed amount of powder comes into it from a hopper. At the next position, the powder is pressed into the dish using a fixed pressure (hydraulic) and a mold suited to the dish; then the molded product is removed. After-

290

New cosmetic science

® Cam rTn

Nylon material \ ^Pressing paper

Metal mold

_Powder into dish

pzzzz]

Inner dish

Hydraulic cylinder

n

Fig. 15.12. Molding process for powder cosmetics.

wards, the mold is cleaned automatically and again fed to a dish. This continuous process is shown in Fig. 15.12. The molded product then goes to an automatic cleaning machine to have powder adhering to its periphery removed and is then put into the final container. Fig. 15.13 shows one of these molding machines.

r ^''

Fig. 15.13. Automatic powder molding machine (Mizuho AP-3).

Cosmetic manufacturing equipment 291

For this type of molding, the pressing conditions are very important so it is necessary to adjust the pressure and number of pressings in accordance with powder characteristics. For instance, in the case of mica and other pearlescent powders, as it is difficult to remove air and compact the powder, the pressing may be done in stages or the pressure varied during one press. Sometimes, however, due to the shape of the dish, it may only be the periphery of the molded product which is hardened. This problem can be solved by adjusting the density distribution of the powder in the dish before pressing or changing the shape of the pressing mold, which makes the hardness uniform.

15.7. Filling and packaging machines The type of filling machine used for cosmetics depends on the state of the material to be filled, the type of container and volume of the contents, and there are many different types. Bottle filling machines are used for lotions and milky lotions, wide-neck bottle or tube filling machines for creams, cardboard drum and bag filling machines for powders (the filling of aerosol containers is described in Chapter 13). A detailed explanation of filling machines will not be given here because of their tremendous variety but their common requirements are accuracy in measuring the amount to be filled, high speed and ease of cleaning. Further, the filling operation must be done in a clean and sanitary environment. In this respect, the filling of eyeliners and mascaras is done in a clean room in order to prevent contamination by microorganisms in the liquid state. In the packaging and finishing processes, labeling machines, printing machines, cartoning machines and weight checking machines are used. The performance of labeling machines has been raised through advances made in the development of adhesives and label papers. Inkjet printers are now much used for the printing of manufacturing codes, etc. Cartoners and robots are used to achieve manpower savings when packing products into cases and cartons.

References 1. Inspection and Guidance Division, Pharmaceutical Affairs Bureau, Ministry of Health and Welfare ed.: GMP for Cosmetics, Yakuji Nippo Ltd., 1988. 2. Kubo, K., Mizuwatari, A. et al: Powder Theory and Applications of Powders, p. 425, Maruzen, 1962. 3. litani, K., Arakawa, M. et al. eds.: Physical Properties of Powders and Engineering (Chemistry Supplement 31), p. 55, Kagaku Dojin, 1967. 4. Shimizu, Ota: Application of New Mixing Technology, p. 301, Technical Information Association, 1989. 5. Hashimoto, T.: Mixing and Kneading Equipment, General Science and Technology Research Institute, 1986. 6. Endo, K., Shikamata, K., Kobayashi, J., Hosaka, H.: Manufacturing Process Charts for Food Supplements, p. 697, Kagaku Kogyosha (Chemical Industries Co., Ltd.), 1989.

16 Regulations on cosmetics Although cosmetics are become more and more closely involved in our daily lives, expectations of them are growing and society's concerns about them are increasing, still very few people are aware of the large number of regulations governing them and the strictness of the quality assurance under which they are manufactured and sold. As cosmetics are used repeatedly, maximum efforts must be made to ensure their efficacy (effectiveness and usefulness) and safety. The various regulations governing cosmetics can be said to be the minimum required pledge to the consumer of assured and constant quality. The major ways that different countries regulate cosmetics are by approval and reporting systems, and by obliging companies to provide certain information on cosmetic container labels or to keep in-house records; or there may be no particular regulations at all. Countries in Asia have adopted license and approval systems while America and many countries in Europe have adopted reporting systems. Furthermore, the definition of cosmetics differs from country to country and, depending on their ingredients, they may sometimes come under the classifications of "cosmetic incorporating pharmaceutical agent", "OTC product" or "ethical drug". For this reason it is necessary to make a thorough study of the regulations in each country. Notwithstanding any variations in the regulatory systems in different countries, it is still the responsibility of the manufacturer to guarantee the quality of his products which also includes a guarantee of their safety. Moreover, as the regulations may change, it is necessary to carefully study the latest ones regarding the manufacture and sale of cosmetics.

16.1. Regulations concerning cosmetics in Japan In Japan an approvals system is in force. There are many types of regulation governing the manufacture and sale of cosmetics and as cosmetics are used on the human body on a daily basis, stipulations regarding their quality, efficacy and safety are made in the Japan's Pharmaceutical Affairs Law^^ (Law No. 145, 1960). This law, which concerns peoples' health, sets forth regulations regarding the quality, efficacy, safety and proper use of drugs, quasi-drugs, cosmetics and medical devices, and plays a very important role in improving the health of the Japanese people and ensuring they can live healthy lives.

292

General provisions Purpose Definitions

1

-Pharmaceutical Affairs Councils ---Central and regional pharmaceutical affairs council-related regulations Pharmacies Permission to establish a pharmacy, approval standards, control duties of controller

Prohibition of exaggerated advertising Prohibition of advertising of drugs, etc. before approval

Japanese Pharmacopeia Standards for ethical drugs, etc. Regulations on drugs Regulations on quasi drugs Items to be indicated on the immediate container, etc Regulations on cosmetics Items to be indicated on the immediate container. etc (Name of manufacturer or importer, name of product, etc. set forth in Ministl-y of Health and Welfare ( M H W ) ordinances supplementary to those mentioned in preceding items) Applic;ible items (Articles 51, 53 57) I'rohibitivn of manufacture, sale, etc. PI-ohibition of exaggerated claims / ,

I

Licensing of manufacturers and importers of drugs, quasi drugs, cosmetics, niedical devices Licensing standards Licenses granted by Governor of the pt-efecture in which the factory (importing office) is located Approval to manufacture (import) drugs, quasi drugs, cosmetics, etc. granted by the hlinister of Health and Welfare (MHU')

I

.

Licensing for sellers of drugs, quasi-drugs and medical devices

I Quality Standards of Cosmetics MFILY Notification No. 322 (standards established on the basis of Article 42 of the Pharn~aceuticalAffairs Law) Ordinal-y cosmetics (prohibited ingredients, Japanese Standards of Cosmetic Ingredients (JSCI), etc.) Special cosmetic products (hormones, antihistamines, etc.) Japanese Standards of Cosmetic Ingredients (JSCI) 1991 : total 592 items 1967 : 114 items established 1970 : 91 items added 1973 : 227 items added, 1 item delated 1982 : 107 items added, 15 items deleted 1985 : 63 items added 1991 : 22 items added. 16 items deleted

Supervision Spot inspections, etc. Disposal, etc. Improvement orders Cancellation of license, approval, etc. Miscellaneous provisions

I Penal regulations

(

of f'hal-niaceutical Affairs Law

Enforcement Regulations of I'harmaceutical Affairs Law Ministerial ordinances with detailed regulations I '1-2)

Items which may be used in [)rugs, etc. Coal-tar colors specified in " T h e M H W Ordinance Designating Coal tar Colors I'ermitted for Use in L)r~lgs,etc. M H W Ordinance N o . 30. 1966 : N o . 3. 1967 : No. 55. 1972 - -

I

may be used in all drugs, quasi drugs and cosmetics Table I Table I1 may be used in external use dr~tgs,external use q u a s i d r u g s and cosmetics Table 111 may be used in external use drugs, external use q ~ r a s i d r u g sand cosmetics which do not come into contact with rnucous membranes

I : I1 items ; 11 : 47 items ; I11 : 25 itetns (total 83 items) (including lakes)

Fig. 16.1. Japan's Pharmaceutical Affairs Law and related legislation.

I

"

294

New cosmetic

science

16.1.1. Regulations in Pharmaceutical Affairs Law concerning cosmetics and quasi-drug products The following describes the regulations in the Pharmaceutical Affairs Law which concern the cosmetic and quasi-drug products mentioned in this book. 16.1.1.1. Definition of cosmetics In Article 2 of the Pharmaceutical Affairs Law, cosmetics are defined as "items applied to the human body by means of rubbing, sprinkling and the like, for the purpose of cleaning, beautifying, adding to the attractiveness, altering the appearance or keeping the skin or hair in good condition, which should be items with a mild action on the human body". Items having a mild action means those which do not have a strong action on the human body even if misused, and which have high safety. More specifically this means the following: (1) items whose purpose is to cleanse the human body: soap, face cleansing cosmetics, shampoo, cleansing lotion, packs, etc. (2) items whose purpose is to beautify the human body: lipstick, foundation and other makeup cosmetics (3) items whose purpose is to enhance peoples' charm: perfume, eau de Cologne, other fragrance products, lipstick, manicure preparations and other makeup cosmetics (4) items whose purpose is to change the appearance: lipstick, mascara, eye shadow and other makeup cosmetics (5) items whose purpose is to maintain the skin and hair in a healthy condition: creams, milky lotions, lotions, hair rinses, hair tonics, hair sprays, etc. 16.1.1.2. Definition of quasi-drug products Quasi-drug products occupy a position mid-way between that of drugs and cosmetics, and the effects which they claim to have are within the scope permitted in the Pharmaceutical Affairs Law. Their definition is given below. However, more specifically, preparations are defined individually on the basis of an overall assessment of such items as ingredients and their quantities, efficacy, method of use, dosage and product form. In Article 2 of the Japan's Pharmaceutical Affairs Law, "quasi-drugs" are described as items which have the purposes listed in (l)-(5) below, a mild action on the human body, and are not equipment or instruments; and items conforming to this and designated by the Ministry of Health and Welfare: (1) prevention of nausea, other such discomfort, bad breath or body odor (2) prevention of prickly heat, festering and the like (3) prevention of hair loss, hair growth promotion or depilatory action (4) extermination and repulsion of rats, flies, mosquitoes, fleas, etc. to maintain human and animal health (5) items conforming to the above designated by the Ministry of Health and Welfare (a) cotton products intended for sanitary purposes (including items incorporating paper and cotton) (b) items having a mild action on the human body: hair color; permanent waving

Regulations on cosmetics 295

lotion; items which, besides their cosmetic purpose, are used for the prevention of acne, chapping of skin, itchiness, rash, chilblains, etc. or those which have the additional purpose of disinfecting the skin or the oral cavity; bath preparations Some actual quasi-drugs and their effects^) are listed in the following: (1) prevention of nausea, other such discomfort, bad breath: mouth freshener (effect: prevention of nausea, motion sickness, bad breath, etc.) (2) prevention of body odor: deodorants (effect: prevention of armpit and other body odor) (3) prevention of prickly heat, festering and the like: talcum powder (effect: prevention of prickly heat, diaper rash, etc.) (4) prevention of hair loss, hair growth promotion: hair growth promoter, hair tonic (effects: prevent hair loss, dandruff, itchiness; promote hair growth, nourish hair, etc.) (5) items with a depilatory purpose: depilatory (effect: removal of unwanted hair on the arms and legs) (6) items with the purpose of exterminating or repelling rats, flies, mosquitoes, fleas and other pests in order to maintain human and animal health: rodenticide (effect: kills rats, repels house mice); insecticide (effect: kills flies, mosquitoes, fleas and other insects); insect repellent (effect: repels mosquitoes, sandflies and the like). (7) cotton products intended for sanitary purposes: sanitary cotton products, cleansing cotton products, sanitary napkins (8) hair color (including decolorants and dye removers) (9) permanent waving lotions (10) items which, besides their cosmetic purpose, are used for the prevention of acne, chapping of skin, itchiness, rash, chilblains, etc. or those which have the additional purpose of disinfecting the skin or the oral cavity: (a) medicated cosmetics (including medicated soap); (effects: prevention of acne, chapping of skin, chilblains and liver spots and freckles due to sun exposure, etc.). (b) medicated dentifrices (effects: prevention of dental caries, pyorrhea, etc.) (11) bath preparations (effects: alleviation of prickly heat, stiff shoulders, neuralgia, hemorrhoids, etc. 16.1.2. Regulations on manufacture and sale of cosmetics and quasi-drug products In addition to the above definitions, the Pharmaceutical Affairs Law also makes various stipulations with regard to such items as the competence of the manufacturer, structure of his premises and equipment at it, manufacturing/importing approvals for quasi-drug products, cosmetics, labeling on products and advertising in order to ensure that manufacturing and selling are done in the proper manner. In outline, these provisions are as follows: (1) Companies must have the necessary "manufacturing or importing license" for cosmetics or quasi-drug products, (a) A company may receive such a license from the Prefectural Governor if, on

296

New cosmetic science

inspection, its competence, structure of the manufacturing premises (or importing office) and equipment at it meet the standards. In the case of cosmetics, if the company wishes to both manufacture and import, a license to manufacture cosmetics is required for each manufacturing location and one for the sale of imported cosmetics for each importing office, (b) It is necessary to apply for a renewal of a manufacturing or importing license every three years. Furthermore, if there are any changes to circumstances for which the license was granted (e.g. changes in company directors, factory structures/equipment) this must be notified within 30 days. (2) "Manufacturing approval" is required for each cosmetic and quasi-drug product to be manufactured and "importing approval" for each such product to be imported. If there are any changes to the approved items, an application must be made for the approval of such changes by the Prefectural Governor. (3) Approval of new ingredients for cosmetics and quasi-drug products is obtained from the Central Pharmaceutical Affairs Council which will examine their safety, efficacy and other aspects. (4) In order to ensure the proper retailing of products, the name and address of the manufacturer or importer, product name, names of ingredients designated by the Minister of Health and Welfare, usage and precautions in use must be displayed on them. (5) In order to prevent drugs and quasi-drugs having a harmful effect on people's health, the Minister of Health and Welfare may establish standards relating to their properties and quality based on recommendations of the Central Pharmaceutical Affairs Council. (6) For cosmetics, it is forbidden to make false statements or exaggerated claims in advertising with regard to such items as manufacturing methods, safety, efficacy and performance. As seen from the foregoing, the Pharmaceutical Affairs Law requires various permissions for each quasi-drug and cosmetic product to be manufactured or imported to ensure that they have the proper quality. They are explained in more detail below. Manufacturing approval for cosmetics may be obtained once an application giving such details as product name, ingredient names, specifications and formulation quantities, manufacturing method and method of use has been made to the Ministry of Health and Welfare, and the product has been screened for safety. As quasi-drug products contain active ingredients, it is necessary to apply for approval of such ingredients with respect to safety and efficacy, as well as for a manufacturing license. In order to apply for such approval, documents giving such details as product name, ingredient names, specifications and formulation quantities, manufacturing method, method of use, indications or effects, product specifications and test results are submitted to the Ministry of Health and Welfare. In the case of cosmetics, the approval of an application takes about 3 months; and, in the case of quasi-drug products, it takes about 6 months. However, in the case of cosmetics, the system is in the process of being simplified and a category approval system^) has now been introduced. Under the category approval system, ingredient lists containing such information as ingredient names, specifications and formulation limits have been published for individual cosmetic categories such as creams, milky lotions and

Regulations on cosmetics 297

foundations. In the case that a cosmetic product consists only of ingredients on the list, if an application for manufacturing or importing approval giving the product name ingredient names and other necessary details is submitted to the Prefectural Government, it is possible to start manufacturing or importing a cosmetic product on the day of submitting the application. It has already been mentioned that the Pharmaceutical Affairs Law contains no more than basic legislation. Consequently, the Ministry of Health and Welfare makes efforts to handle matters relating to it as specific cases, give advice in cases of doubt and issue Notifications concerning related matters. Furthermore, the Japan Cosmetic Industry Association is aiming to ensure that the manufacture of cosmetics and their quality control (cosmetics GMP) is done in the proper manner through the implementation of its own standards in Technical Guidelines for the Manufacturing and Quality Control of Cosmetics^) (Notification No. 57, 1988).

16.2. Laws relating to cosmetics in Japan In order to manufacture or sell cosmetics, the basic law that must be obeyed is the Pharmaceutical Affairs Law. In effect, this means having to know the requirements for ensuring that such cosmetics always have the proper quality, and obeying various other laws relating to them. Some of these laws are listed in Table 16.1. Table 16.1. Laws relating to cosmetics No.

Law

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Pharmaceutical Affairs Law Commodity T a x Law High-pressure Gas Control Act Fire Services Act Basic Law for Consumer Protection Anti-monopoly Law Unfair Competition Prevention Law Patent Law Weights and Measures Act Design Law Utility Model Law Trademark Law Food Sanitation Act Poisonous and Violent Substances Control Law Industrial Standards Act The Law against Unjustifiable Premiums and Misleading Representation Government Monopoly in Alcohol Act Basic Law for Environmental Pollution Control Law Concerning Examination and Regulations of Manufacture, etc. of Chemical Substances Waste Management and Public Cleansing Law

17 18 19 20

Law number

Year enacted

145 48 204 186 78 54 14 121 207 125 123 127 233 303 185 134

1960 1962 1951 1948 1968 1947 1934 1959 1951 1959 1959 1959 1947 1950 1949 1962

No. 32 No. 132 No. 117

1937 1967 1973

No. 137

1970

No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No.

298 New cosmetic science

Cosmetics consist of oil and fat based raw materials, surfactants, colors, fragrances, humectants, antibacterial agents and other constituents. These raw materials are made into cosmetics using emulsification, dispersion, solubilization and other basic techniques, and after being put into containers, packed and inspected, the finished product reaches the consumer through cosmetic shops, department stores, supermarkets and other retail outlets. The various laws relating to raw materials, containers, manufacturing plants, products and marketing activities can therefore be said to be laws that relate to cosmetics. 16.2. L Regulations relating to raw materials The Japanese Standards of Cosmetic Ingredients^— (Notification No. 322, 1967), based on Paragraph 2, Article 42 of the Pharmaceutical Affairs Law, were established to further improve the quality of cosmetics and they have been revised 6 times. In these standards, specifications have been set down for the raw materials normally used in cosmetics to ensure that they are of the proper quality and to make them safer. Six hundred different raw materials are now covered. Other specifications relating to cosmetic raw materials are found in the Japanese Pharmacopoeia (standards for drugs), official raw materials lists in The Japanese Standards of Food Additives, and The Japanese Cosmetic Materials Codex I-VP-^^) (issued between August 1986 and September 1991), prepared as a manual of standards for the raw materials which have already seen use in cosmetics under the supervision of the Pharmaceuticals and Cosmetics Division of the Ministry of Health and Welfare's Pharmaceutical Affairs Bureau. For quasi-drug products. The Japanese Standards of Quasi-drug Ingredients was issued in June 1991. As cosmetics are used on the human body, it is necessary to use the raw materials listed in the standards and specifications as they have sufficiently high quality and high safety. Furthermore, applications for approval of cosmetic products using unlisted raw materials (new ingredients) must be accompanied by safety data and other necessary information. Approval will be given once this information has been examined by the Central Pharmaceutical Affairs Council. Examples of other regulations relating to cosmetics are those in List of Existing Chemical Substances based on the Law Concerning Examination and Regulations of Manufacture of Chemical Substance, the Poisonous and Violent Substances Control Law, and the Government Monopoly in Alcohol Act. 16.2.2. Laws relating to product contents 16.2.2.1. Laws relating to cosmetic products The Quality Standards of Cosmetics^^^^ has been established in 1967 (MHW Notification No. 321, 1967) and it has been revised 7 times since then. In order to prevent cosmetics from having a damaging effect on human health, these standards stipulate ingredients which are prohibited in cosmetics and include formulation standards for cosmetics containing special ingredients (special cosmetic products). Some of the stipulations are as follows:

Regulations on cosmetics

299

(a) (1)

Prohibited ingredients Ingredients prohibited in cosmetics under Quality Standards for Cosmetic Products (i) dichlorophene (ii) mercury and mercuric compounds (iii) hydroquinone monobenzylether (iv) bithionol pilocarpine (V) (vi) halogenated salicylic anilide (2) Ingredients prohibited in notifications (Notification 2 No. 321, 1986) (i) antihistaminics other than those of the aminoether type (ii) hormones other than estradiol, estrone and ethinylestradiol (iii) vinyl chloride (monomer) (iv) bismuth compounds other than bismuth oxychloride chloroform (V) (vi) vitamin L] and L2 (vii) local anesthetics such as procaine (viii) formalin (ix) methyl alcohol (x) boric acid, sodium perborate, borax (the use of borax is acceptable when its purpose is emulsifying beeswax or bleached beeswax) (b) Special cosmetic products (1) For cosmetic products containing hormones, the types of hormone (follicle hormones) and their amounts are stipulated. ® The total amount of hormone contained in 1 g of cosmetic products applied to the head, mucous membranes or the oral cavity must not exceed 200 International Units (lU). @ For cosmetic products used on parts other than in ® containing aliphatic lower monohydric alcohols, the total hormone content in 1 g of product must not exceed 200 lU (excluding cosmetic products containing such as alcohols for the exclusive purpose of dissolving their ingredients). @ For cosmetic products other than those in ® and ©, the total hormone content in 1 g of product must not exceed 500 lU. In the table below the number of lU/g have been converted to mg/100 g or 100 ml of product. Follicle Hormones Estradiol Estrone Ethinylestradiol

(2)

® and ®

(D

0.4 mg max. 2.0 mg max. 0.2 mg max.

1.0 mg max. 5.0 mg max. 0.5 mg max.

For cosmetics containing antihistaminics, stipulations are made regarding parts of the body they are used on, the type of antihistaminic and its content: (i) body part: limited to cosmetics used on the head (ii) type: must be aminoether type (iii) content: not more than 0.01 g/100 g of product

300 New cosmetic science Table 16.2. Permitted amounts of benzoic acid, salicylic acid and other pharmaceutical agents in 100 g of a cosmetic product Agent Aluminium chlorohydroxy allantoinate Benzoic acid Benzoates Chlorocresol Salicylic acid Salicylates Phenyl salicylate

(3) (4) (5) (6) (7) (8) (9) (10)

Amount (max. amount) Ig 0.2 g Ig 0.5 g 0.2 g Ig Ig

Agent Sorbic acid and its salts Dehydroacetic acid and its salts Parahydroxybenzoic acid esters Phenol Hexachlorophene Polyoxyethylene lauryl ether (8-^ 10 E. 0.) Resorcin

Amount (max. amount) 0.5 g 0.5 g Ig 0.1 g 0.1 g 2g 0.1 g

Vitamins used in cosmetics must be any other than vitamin Lj or L2. The addition of methyl alcohol is not acceptable. The impurity content of ethanol must be not more than 0.2 ml/100 ml of product. If cosmetics contain benzoic acid, salicylic acid, etc., the amounts per 100 g of product must be not more than those shown in Table 16.2. If cosmetics contain isopropylmethylphenol, etc., the amounts per 100 g of product must be not more than those shown in Table 16.3. However, soaps, shampoos and other rinse-off products are excepted. For cosmetics containing cantharides, ginger or capsicum tinctures, the total included amount must not exceed 1 g per 100 g of product. For cosmetics containing paraamino benzoic acid or its esters the total included amount must not exceed 4 g per 100 g of product. For cosmetics containing thiram, the amounts must not exceed those given below. (i) 0.5 g per 100 g for soap, shampoo and other rinse-off products (ii) 0.3 g per 100 g for cosmetics other than those in (i). Sodium TV-lauroyl sarcosinate may only be contained by cosmetics which are rinsed away immediately after use such as dentifrices, soap and shampoo. The amount in dentifrices must not exceed 0.5 g per 100 g of product. Table 16.3. Permitted amounts of isopropylmethylphenol and other pharmaceutical agents in 100 g of a cosmetic product Agent

Isopropylmethylphenol Benzalkonium chloride Orthophenylphenol Chlorhexidine gluconate Cinoxate Alkylisoquinolinium bromide Trichlorocarbanilide

Amount (max. amount) 0.1 g 0.05 g 0.3 g 0.05 g 5g 0.05 g 0.3 g

Agent

Amount (max. amount)

Zinc paraphenol sulfonate Halocarban 2- ( 2 - h y d r o x y - 5 - m e t h y l p h e n y l )

2"g 0.3 g

benzotriazole 2-hydroxy-4-methoxybenzo-

7g

phenone

5g

Regulations on cosmetics 301

(11) Undecylenic acid monoethanol amide may only be contained by rinse-off products such as soap and shampoo. The above standards have been provided for ingredients contained by particular cosmetics. In addition, the following general requirements also apply. (1) The arsenic content of cosmetics must not exceed lOppm as arsenious acid (Notification No. 81, 1968). Although there is no firm stipulation regarding lead content, the maximum desirable amount is taken as 20-30 ppm. (2) Aerosol cosmetics must conform to the standards regarding the gases which may be used in them such as those in the High-pressure Gas Control Act and Notification No. 742 issued in 1989 which states that they must not contain "Specified Chlorofluorocarbons" (specified chlorofluorocarbons: dichlorodifluoromethane, dichlorotetrafluoroethane, trichloromonofluoromethane). 16.2.2.2. Regulations on quasi-drug products Notification No. 464^) issued in 1962 sets forth standards for the inclusion of the following substances in medicated cosmetics, one of the categories of quasi-drug products. (1) Hormones: the inclusion of hormones in medicated cosmetics is limited to Follicle Hormones (FH) and Adrenocortical Hormones (ACH) and their proportions (total amount in 100 g or 100 ml of product) are as set forth in Tables 16.4 and 16.5. (2) Homosulfamine: not exceeding 1 g per 100 g of product (3) Cantharides tincture: not exceeding 1 ml per 100 g of product (4) The inclusion of the following substances is not permitted, (i) hormones other than those in (1) (ii) sulfanilamide and its derivatives (iii) mercury, mercuric compounds and formalin (iv) vitamin Li and L2 (v) nitrofuran compounds (vi) strontium compounds, selenium compounds, cadmium compounds (vii) antibacterial substances (antibiotics) (5) Other substances whose use is not permitted for use in quasi-drug and other cosmetic products in accordance with notifications issued by the Director of the Pharmaceutical Affairs Bureau, etc. (i) bithionol (ii) vinyl chloride (monomer) (iii) halogenated salicylanilide group antimicrobials (tribromsalan, dibromsalan, metabromsalan, etc.) Table 16.4. Permitted amounts of follicle hormones Follicle Hormones

Used on head, mucous membranes or in oral cavity

Other cases

Estradiol and its esters Estron Ethinylestradiol Other Follicle Hormones

0.8 mg max. 4.0 mg max. 0.4 mg max. 4.0 mg max. as estrone

2.0 mg max. 10.0 mg max. 1.0 mg max. 10.0 mg max. as estrone

302 New cosmetic science Table 16.5. Permitted amounts of adrenocortical hormones Adrenocortical Hormones

All medicated cosmetics

Cortisone and its esters Hydrocortisone and its esters Prednisone Prednisolone

2.5 mg max. 1.6 mg max. 0.61 mg max. 0.5 mg max.

(iv) chloroform (v) bismuth subnitrate (vi) specified chlorofluorocarbons The Standards for Permanent Waving Agents^) (Ministry of Health and Welfare Notification No. 280, 1968) and Standards for Sanitary Napkins^) (Ministry of Health and Welfare Notification No. 285, 1966) are standards for quasi-drug products. Products which require precautions for use to be displayed on them include permanent waving agents, hair color, bleaches and medicated soaps, shampoos, rinses and shaving preparations containing bactericides. 16.2.3. Regulations concerning

containers

This section gives a general description of the regulations governing containers and includes those regulating items displayed on them. The Pharmaceutical Affairs Law and the Fair Competition Codes stipulate items which must be displayed on containers in order to prevent harm due to improper use, etc.. The Fair Competition Codes make stipulations regarding the items displayed on cosmetic products on the basis of Article 10 Item 1 in the Law against Unjustifiable Premiums and Misleading Representation (Law No. 134, 1962). 16.2.3.1. Items in labels displayed on containers or packaging The Pharmaceutical Affairs Law stipulates that the following must be clearly displayed in Japanese on the outside of containers or packaging in a place where they can be easily seen. (1) Name of product (2) "Quasi-drug Product" in the case of a quasi-drug product (3) Name and address of manufacturer or importer (4) Production code or number (5) Contents (weight, volume, number of items, etc.) (6) Names of ingredients when the product contains those designated by the Ministry of Health and Welfare (7) Expiration date (not required when the quality is guaranteed for 3 years or over) The following stipulations concern exceptions to the above regarding the display of ingredients and amount of contents. (1) When ingredients designated by the Ministry of Health and Welfare are displayed on the outer packaging they do not have to be displayed on the container.

Regulations on cosmetics 303

(2)

Ingredients having the potential to cause allergies and other skin problems must be displayed for the reference of consumers when they purchase the product. (3) For cosmetic products only, the amount of the contents does not have to be displayed when the product contains 10 g or 10 cc or less and there is little space for displayed items on the container or outer packaging. In addition, the method of use, amount to be used, precautions in use and handling should be indicated on the package insert or container/packaging. Further, in accordance with the Fair Competition Codes, it is also necessary to display (1) the country of origin (for imported items only) and (2) the product category (in the case of cosmetic products) in Japanese in a conspicuous place on the outside of the container or packaging. In the amount of contents description, the weight should be indicated for cosmetic products whose viscosity is 10,000 cps or above at 20°C and aerosol products, and the volume of the contents for products whose viscosity is less than 10,000 cps. Further, standards are set forth in Notification No. 546, 1959 for discrepancies between the displayed and actual contents. 16.2.3.2. Other official regulations, etc. In addition to those in the Pharmaceutical Affairs Law, attention must also be paid to the stipulations on labeling regarding cosmetics containing alcohol and other inflammable substances in the Fire Services Act (Law No. 186, 1948) and in the High-pressure Gas Control Act (Law No. 204) regarding aerosol cosmetics. The Japan Cosmetic Industry Association's own standards (Notification No. 2, 1978) for the labeling of cosmetics should also be observed. Furthermore, efforts should be made to ensure that labels prevent consumers from selecting products improperly. 16.2.3.3. Container form and materials There are no particular stipulations on the form of containers or the materials they are made from; however, the use of containers in forms which could cause cosmetics to be mistaken for drugs (e.g. injection ampules) must be avoided and the material used should help to ensure safety and be suited to the product. The container material should be tested for its chemical resistance, resistance to the contents strength and sealing qualities before use. 16.2.4. Regulations on marketing There are also standards to ensure that cosmetic products of the proper quality are marketed to the consumer in the proper manner (advertising, etc.). In order to prevent exaggerated advertising, on the basis of Article 66 in the Pharmaceutical Affairs Law (Prohibition of False or Exaggerated Advertising, etc.). Standards for Fair Advertising Practices for Drugs, Quasi-drugs, Cosmetics, Medical Devices, etc.^^ was drawn up in a Notification from the Director of the Ministry of Health and Welfare's Pharmaceutical Affairs Bureau (Notification No. 1339, 1980). These standards put limits on the kind of statements which may be made regarding indications, effects and safety in order to avoid false and exaggerated statements in product advertising.

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The following are examples of other notifications based on the spirit of basic legislation designed to protect the consumer. (1) Sale of Cosmetics together with Prizes (Notification 431, 1960) (2) The Law Against Unjustifiable Premiums and Misleading Representation (Law No. 134, 1962) (3) Restrictions on Offering Prizes in Excess of Normal Trade Custom (Fair Trading Commission Notification No. 5, July 1962) (4) Agreement of the Japan Cosmetic Industry Association and Other Organizations Concerning Self-control of the Advertising Practice to Offer Prizes and Premiums (Notification No. 117, 1965) (5) Agreement on Self-control of the Advertising for Cosmetics and Dentifrices (Notification No. 53, 1967) (6) Fair Competition Codes with Regard to Items in Labels on Cosmetics, Soaps and Dentifrices (Notifications Nos. 75 and 82, 1971; Notification No. 21, 1975) (7) Handling of Cosmetics for Consumer Preference (Notification No. 23, 1983) (8) Voluntary Standards for Packed Cosmetic Assortments (including quasi-drug products) (Notification No. 45, 1983) From the above brief description, we can appreciate just how many different regulations there are on cosmetics from manufacturing through to marketing. Further, because they represent the minimum pledge to the consumer, as was mentioned at the beginning of this chapter, each cosmetics company is carrying out research and development in earnest to ensure excellent and highly safe products. Although this chapter has concentrated on the Japanese regulations on cosmetics thus far, it is also essential to collect and analyze information with regard to FDA (Food and Drug Administration of the US) regulations and those of other countries. However, in order to provide very useful, highly safe cosmetics to consumers, efforts over and above those necessary to ensure that they comply with the various regulations must be made. In the times to come, as advances are made in cosmetics technology, we will surely see much more technically-related legislation enacted in order to ensure that the consumer is protected.

16.3. Regulations on cosmetics in other countries (Asia, Oceania, North America, South America and Europe)!^) A brief description of the various regulatory systems in force in various other countries will now be given; in Japan it is the approval system. The reader should refer to the CTFA (Cosmetic Toiletry and Fragrance Association; USA) publication on this subject for further information. 16.3J.

Asia

Taiwan (approval system). The system in Taiwan classifies cosmetics into those used on other parts other than the eyes and eyelids, those used on the eyes and eyelids, and cosmetics containing pharmaceutical agents. When formulae contain ingredients listed in

Regulations on cosmetics

305

Taiwan's Health Control Regulations or in amounts exceeding the limits in them, it is necessary to exercise caution because such products are treated as cosmetics containing pharmaceutical agents. (1) Cosmetics used on parts other than the eyes and eyelids: reporting and approval not required in accordance with regulation regarding products exempted from applications. (2) Cosmetics used on the eyes and eyelids: an application giving the product name, details of the product form, where it is used on the body, names of ingredients, etc. is submitted for approval. Specifications are required for ingredients not included in official lists. (3) Cosmetics containing pharmaceutical agents: for products coming under the categories of Suncare Cosmetics and Whitening Cosmetics, the application for approval to the Ministry of Health must contain such information as that on product specifications, test results, testing methods and test results for special ingredients (ingredients listed in Taiwan's Health Control Regulations) and details of items displayed on the product in addition to the above in order to gain approval. In cases where indications and effects are claimed for a product, usefulness data may be required as evidence. Republic of Korea (approval system). Cosmetics are classified into cosmetics and quasidrug products. (1) Cosmetics: for approval, an application containing such information as product name, names of ingredients and their quantities is made to the Ministry of Health. When new ingredients are incorporated, documentation giving their specifications and safety data for both the new ingredients and the product is also required. (2) Quasi-drug products: in the case of quasi-drug products such as mouth fresheners, deodorants, bath preparations, hair growth promoters, hair color and insect repellents, in addition to the above, documentation containing such information as product specifications and testing methods and testing methods for special ingredients must also be submitted to the Ministry of Health in order to gain approval. Thailand (approval system). Cosmetics are classified into the Cosmetics and Special Cosmetics categories. When the product contains regulated ingredients it falls into the special cosmetics category. (1) Cosmetics: documentation containing such details as product name, names of ingredients and their amounts are submitted to the Ministry of Health in order to gain approval. In the case of cosmetics containing new ingredients, their specifications and other information on them is also required. (2) Special Cosmetics: this covers such items as cosmetics containing regulated ingredients, dandruff prevention agents, permanent waving lotions, hair colors, hair growth promoters and antiperspirants. Approval is obtained by submitting specifications for the ingredients used in them and details of testing methods and test results for special ingredients to the Ministry of Health in addition to the above information. If the product claims indications and effects, usefulness data may also be required as evidence.

306

New cosmetic

science

Malaysia (approval system for some products). Cosmetics are classified into the Cosmetics and Special Cosmetics categories. (1) Cosmetics: neither reporting nor approval required at the present time. (2) Special cosmetics: covers such items as anti-dandruff agents, deodorants, whitening cosmetics, shampoos containing pharmaceutical agents and insect repellents. Approval is obtained by submitting such information as product name, product form and part of body used on, names and quantities of ingredients, ingredient specifications, product specifications, testing methods and test results, special ingredient testing methods and test results, and details of items displayed on the product to the Ministry of Health. When there are new ingredients in the formula, safety data for both the new ingredients and the product are also required. When indications and effects are claimed, usefulness data is also needed as evidence to them. Indonesia (approval system). Approval is obtained by submitting such information as product name, names and quantities of ingredients, ingredient specifications and test results, product specifications and test results, and details of items displayed on the product to the Ministry of Health. When indications and effects are claimed, usefulness data is also required as evidence. Peoples' Republic of China (approval system). Cosmetics are classified into the Cosmetics and Special cosmetics categories. (1) Cosmetics: documentation containing such details as product name, names of ingredients and their amounts are submitted to the Ministry of Health in order to gain approval. (2) Special cosmetics: This covers such items as hair growth promoters, permanent waving lotions, hair colors, whitening cosmetics and antiperspirants. Approval is obtained for them by submitting such information as product name, ingredient names and quantities, ingredient specifications, product specifications and testing methods, and product safety data to the Ministry of Health. Philippines (approval system). Approval is obtained by submitting such information as product name, ingredient names and quantities, ingredient specifications, product specifications and testing methods, and special ingredient testing methods to the Ministry of Health. When indications and effects are claimed, usefulness data is also required as evidence. Singapore. There are no regulations on cosmetics as the present time. 16.3,2,

Oceania

Australia (some products come under approval system). Although there is no obligation for reporting on general cosmetic products, for items like sunscreen cosmetics which are classified as being for therapeutic use, approval has to be obtained from the Ministry of Health by submitting an application containing such information as product name, ingredient names and quantities, product specifications, testing methods and test results.

Regulations on cosmetics 307 special ingredient quantification methods and quantification results, usefulness data and items displayed on the product. New Zealand There are no regulations on cosmetics at the present time. 16.3.3. North America USA (reporting system). The cosmetic product name and details of its ingredients are voluntarily reported to the FDA within 60 days of marketing. However, in the case of such items as sunscreens, antiperspirants and acne treatment preparations which come under the OTC category, reporting is obligatory and such information as the product name, product form and where used, ingredient names and quantities, and items displayed on the product must be submitted to the FDA. Canada (reporting system; OTC category products: approval system). For general cosmetic products, such information as the product name, product form, where used, and ingredient names are reported to the Ministry of Health within 10 days of marketing. In the case of such items as sunscreens, antiperspirants and acne treatment preparations which come under the OTC category, approval has to be obtained by submitting such information as product name, product form and where used, ingredient names and quantities, product specifications and testing methods, quantification methods for active ingredients and preservatives, and items displayed on the product to the Ministry of Health together with the OTC application documents. When the product contains ingredients not on official lists, their specifications and testing methods are also required. 16.3.4. South America Chile (approval system). Approval is obtained by submitting such information as the product name, product form and where used, ingredient names and quantities, ingredient specifications, product specifications and items displayed on the product to Ministry of Health. In the case of sunscreen products, it is also necessary to submit details of the quantification methods used for the sunscreen agents. Venezuela (approval system). Approval is obtained by submitting such information as the product name, ingredient names and quantities, ingredient specifications, product specifications and items displayed on the product to Ministry of Health. Argentina (reporting system). Such information as the product name, ingredient names and quantities are reported to the Ministry of Health. 16.3.5.

Europe

UK, Germany, Belgium, Netherlands and Luxembourg. There is no obligatory reporting for general cosmetic products. France (in-house records kept). France requires companies to keep in-house records containing such information as product name, ingredient names and quantities, ingredi-

308 New cosmetic science

ent specifications and testing methods, product specifications, testing methods and test results, product safety and usefulness. Italy (in-house records kept). Reporting is unnecessary but in-house records containing such information as product name, ingredient names and quantities must be kept. Greece (reporting system). In the case of cosmetics imported from within the EU, the product name is reported to the Greek Ministry of Health. In the case of cosmetics from outside the EU, the product name, ingredient names and quantities, product specifications and so forth, are reported to the Ministry of Health before clearing customs. Spain (reporting system). The product name, product form and where used, ingredient names and quantities, product specifications, product safety data and other such information are reported to the Ministry of Health. Portugal (reporting system). The product name, product specifications and test results are reported to the Ministry of Health within 30 days of marketing. Switzerland (reporting system; some products under approval system). For general cosmetic products, the product name, product form and where used on the body are voluntarily reported to the Ministry of Health. However, for cosmetics stating that they contain vitamins, it is necessary to apply for approval to the Ministry of Health and the Vitamin Analytical Research Institute, submitting documentation containing such details as the product name, product form and where used, the ingredients and the items displayed on the product. Austria (some products under approval system). Though there is no obligation to file reports for general cosmetic products, approval for special cosmetics containing ingredients not listed in the Government drug list, an application for approval must be made to the Ministry of Health, submitting documentation containing the product name and other details as well as usefulness data. Denmark (reporting system). The product name and names of ingredients are reported to Denmark's Environment Ministry by the date of marketing. Sweden (reporting system). The product name is reported to the Ministry of Health within 30 days of marketing. Norway (reporting system). The product name is reported to the Ministry of Health within 30 days of marketing. Finland (some products under reporting system). In the case of cosmetics for use by professional beauticians, the product name is reported to the Ministry of Health within 30 days of marketing.

Regulations on cosmetics 309

References 1. Standards and Certification Systems Concerning Drugs in Japan, 3rd. edn., Yakugyojiho Ltd., 1992. 2. Pharmaceuticals and Cosmetics Division, Pharmaceutical Affairs Bureau, Ministry of Health and Welfare, ed.: Guide to Quasi-drug and Cosmetic Regulation in Japan, Editorial supervision, Yakuji Nippo Ltd., 1992. 3. Japanese Standards of Cosmetics Ingredients, Yakuji Nippo Ltd., 1979. 4. Japanese Standards of Cosmetics Ingredients, 2nd. edn., Yakuji Nippo Ltd., 1985. 5. Supplement I to the Japanese Standards of Cosmetics Ingredients, 2nd. edn., Yakuji Nippo Ltd., 1986. 6. Supplement II to the Japanese Standards of Cosmetics Ingredients, 2nd. edn., Yakuji Nippo Ltd., 1992. 7. The Comprehensive Licensing Standards of Cosmetics by Category Part I, Yakuji Nippo Ltd., 1986. 8. The Comprehensive Licensing Standards of Cosmetics by Category Part II, Yakuji Nippo Ltd., 1987. 9. The Comprehensive Licensing Standards of Cosmetics by Category Part III, Yakuji Nippo Ltd., 1988. 10. The Comprehensive Licensing Standards of Cosmetics by Category Part IV, Yakuji Nippo Ltd., 1989. 11. The Comprehensive Licensing Standards of Cosmetics by Category Part V, Yakuji Nippo Ltd., 1990. 12. The Comprehensive Licensing Standards of Cosmetics by Category Part VI, Yakuji Nippo Ltd., 1991. 13. International Resource Manual, 3rd. edn.. Cosmetic, Toiletry and Fragrance Association, Washington, DC.

17 Cosmetics and information As mentioned in Outline of Cosmetics, cosmetics have a close connection with several scientific disciplines and areas related to them. Cosmetic products can be said to be the result of the creative use of the vast amount of information derived from them and research results. Putting this another way, much know-how and an extremely large amount of information are put to use at all stages from the planning of a cosmetic product through R&D and production right up to its marketing. In this chapter, we shall be looking at the importance of information from the R&D aspect, mention various reference books and journals related to cosmetics and touch on the increasing use of databases resulting from the widespread use of computers which are all helping us to gain a deeper understanding of cosmetics.

17.1. Importance of information in research and development Briefly speaking, as cosmetics research can move straight into the commercialization of a product right from the product planning stage through the utilization of one's accumulated know-how, it has many different levels which begin from basic research and then go on through the stages of applied research and product research to the first version of the finished products. Fig. 17.1 shows the information required at each stage for the case in which R&D proceeds from basic research, through applied research on to product research and how it is related to them. 17.1.1. Documentation

activities

By documentation activities, we mean a series of activities comprising the collection of technical information, its processing, investigation, analysis, assessment and dissemination which are carried out in an organized manner. Formerly, it was possible for researchers to cope with this individually during spare time in their research when they would collect information and process it (e.g. making card indexes for technical papers they had selected from journals). However, now that we are in the age of information, there is a limit to the amount of information that one can collect individually, there are leaks of confidential information and, for the most part, it has become very difficult to search out the necessary information from the mountains that exist. Under these circumstances, it is essential to adopt an organized approach in order to carry out research effectively. As the major factors behind this, we can give the explosive increase in the volume of information and the proliferation of its sources. As evidence of the former in the field of chemistry, every year at least 500,000 310

311

Cosmetics and information

Information collection N by individuals /' T

n o u

05 (D

en a;

1

w

^o 03 ;-( CU

X

o u

C3 OJ

W

c«


(D

u C/2 03

m

;3

T3 O

a a

<

Model change" -development of next generation product

o c

PH

Documentation activities

,....^

^

/ Setting goals for "\ \ information use ,' ^ \

Technical information Patent information Market information

k—

Management information k Others U

Fig. 17.1. Information in research and development.

technical papers and patents are entered in Chemical Abstracts, the largest collection of abstracts in the world, and this volume appears to be increasing year by year. The latter is borne out by scientific journals which focus on the publication of research reports. Information is no longer concentrated in a few specialist journals on specific fields: it is now available for a tremendous range of subjects in upwards of 10,000 journals in the fields of science and technology. Moreover, in the view of the fact that cosmetics research involves such a tremendous range of different subjects, the collection of information is extremely difficult because the sources are now so diverse. Cosmetics companies, whether large or small, all have their own libraries for documents and books. These libraries occupy a central position in the organization for documentation activities and provide backup for R&D activities. The goals of such documentation activities is to form a strategic link between the resource of information and R&D activities, ensure the efficient generation of research results and connect it with new product development. 17.12,

Information

sources

The information required for cosmetics research can be broadly divided into technical information and patent information. (Although we will treat these two types of information separately here, patent information is also considered to be part of technical information.)

312 New cosmetic science Table 17.1. Categories of technical information Category

.2 a B

il

Published form

Technical documents (Papers)

Journals or books

Government, company, university and other types of report

As above

Patents/utiHty models

Unexamined patent application, examined patent application

Society/association related

Journals

Regulatory information

Journals, newspapers, ment publications

Information from raw material manufacturers, etc.

Catalogs

Govern-

Research reports (basic, applied, product research) Testing reports (analysis, safety, preservation, materials, stability, etc.) Formulation (including manufacturing processes), etc.

Technical information can be broadly divided into such in-house information as research and testing reports and such external information as papers in journals and other types of report (Table 17.1). Patent information consists of information on rights exemplified by patent rights, utility model property and other rights based on the Industrial Property Law. In concrete terms this means unexamined and examined patent application published in Japan and other countries. It goes without saying that patent information receives the greatest emphasis in cosmetics research. If a company markets a product not knowing that the patent rights are held by someone else (patent infringement) then the patent holder will make a complaint and the company infringing the patent will be penalized in such ways as having to recall the product and pay a huge amount of compensation. Patent infringement is becoming an increasingly serious issue globally and with the practice of making an appropriate payment for intellectual property rights now becoming commonplace, one cannot be too cautious with regard to patent information. The next important type of information is technical papers and those published in journals are treated with particular importance. Technical papers are not just important for constantly keeping up with the latest trends in technology, it is also essential to use them to study and analyze the results of past research in order to prevent duplicate investments and determine the direction of future research. Moreover, because cosmetics (as well as quasi drug products) are subject to so many government regulations right through manufacturing to marketing, it is necessary to keep constantly up-to-date by collecting information from your own and other countries as quickly as possible.

17.2. Books and journals containing cosmetic-related information We now mention some of the major books and journals providing a useful reference for

Cosmetics

and information

313

Table 17.2. Major books on cosmetics and related subjects Book Title

10 11 12 13 14 15 16

Handbook of Cosmetic Materials Chemistry and Manufacture of Cosmetics, 2nd ed., vol. 1~4 Handbook of Cosmetic Science Formulation and Function of Cosmetics (Kosmetologie (1959)-translated from the Germany by G.L. Fenton) Harry's Cosmetology Cosmetics : Science and Technology, 2nd ed., vol. 1~3 Perfumes, Cosmetics and Soaps, 8th ed., vol. 1—3 Kosmetologie AMA Book of Skin and Hair Care Professional Skin Care Manual Biokosmetik Cosmetic Science vol. 1~2 Cosmetic Science Science of Cosmetics Cosmetic Science, 13th ed Latest Developments in Cosmetic Chemistry, Enlarged ed. Modern Cosmetic Science Cosmetic Science Guidebook

H.W. Hibbott J. S. Jellinek

Year of publication Interscience Publishers 1954 Vol. 1—2, D. Van Nostrand 1962 Vol. 3—4, Continental Press 1975 Pergamon Press 1963 Wiley-Interscience 1970

R.G. Harry E. Sagarin, M. S. Balsam

Leonard Hill Books Wiley-Interscience

Publisher

Author L. A. Greenberg, 0. Lester M.G. deNavarre ed.

W. A. Poucher, G. M. Howard J. S. Jellinek American Medical tion S. Tremblay R. A. Eckstein M. M. Breuer C. Tsukamoto T. Tamura (editor) T. Ikeda (editor) 0. Okuda (editor)

Halstead Press, John Wiley & Son Huthig Associa- Lippincott

H. Kishi (editor) Society of Cosmetic Chemists of Japan (editor) 19 Latest Advances in Cosmetic Cosmetic Science Research Association (editor) Science 20 General Knowledge on Cosmetics American Medical Association (editor), supervised by R. and Beauty Hayakawa 21 Latest Developments in Cos- T. Inoue (editor) metics Testing 22 Handbook of Cosmetics Manu- F. Mori (editor) facturing Guidelines 23 The Science of Fragrance and O. Okuda (editor) Cosmetics 24 Cosmetic Science and the Skin Y. Takase (editor) 25, Science of Cosmetic Prepara- S. Noro, M. Koishi tions 26 Latest Advances in Cosmetic and E. Sugiura, H. Ueda (editors) Fragrance Science 27 Japaese Standards of Cosmetic P h a r m a c e u t i c a l Affairs Ingredients, 2nd ed. Bureau, Ministry of Health and Welfare 28 Commentary on Japanese Stan- Society of Japanese Pharmad a r d s of C o s m e t i c In- copoeia (editor) gredieients, 2nd ed. 29 Skincare Handbook T. Ozawa 30 Aging and the Skin Y. Takase, M. Ishihara (editors) 31 Practical Knowledge on Cos- T. Kakihara metics 2nd ed. 32 Cosmetic Manufacturing Appli- P h a r m a c e u t i c a l Affairs cations Guidebook, 4th ed. Bureau, Ministry of Health and Welfare 2nd 33 How to Age Successfully Y. Fukuhara et al 34 How to Age Successfully II S. Yamauchi et al 35 Cosmetic Science-Theory and T. Tamura, H. Hirota Practice 36 Functional Cosmetics Japan Cosmetic Science Research Association (editor) 37 Dermatology for Cosmetic Chem- K. Toda ists & Medical Professionals 17 18

1973 1972 1974 1974 1976 1976

Prentice Hall International Verlag Fritz Majer & Sohn Academic Press Nankodo Japan Hair Research Institute Nanzando Co. Hirokawashoten

1978 1979 1980 1971 1976 1978 1978

Kodansha Yakuji Nippo Ltd.

1979 1979

Yakuji Nippo Ltd.

1980

Shukanshogyo (Cosmetic Industry Weekly)

1980

Hirokawashoten

1980

Fragrance Journal Co.

1981

Hirokawashoten

1982

Nanzando Co. Fragrance Journal Co.

1982 1983

Hirokawashoten

1984

Yakuji Nippo Ltd.

1983

Yakuji Nippo Ltd.

1984

Kodansha Seishishoin

1986 1986

Toyokeizaishimposha

1987

Fragrance Journal Co.

1988

Kyuryudo Kyuryudo Fragrance Journal Co.

1989 1990 1990

CMC Ltd.

1990

Bunkodo

1990

314 New cosmetic science

research on cosmetics. The information they provide includes that on basic cosmetic knowledge, raw materials, manufacturing methods and formulation. 172,1.

Books

(monographs)

There are less books on cosmetics than for other major fields. In general, they were published a long time ago and although some of them have been expanded and revised in recent years there are not many new titles. Table 17.2 lists the major books on cosmetics and cosmetic-related subjects (specialist books on fragrances are not included). The International Federation of Societies of Cosmetic Chemists (IFSCC), has been holding authoritative international scientific conferences on cosmetic research once every 2 years since 1959. Having presentations from many different countries, these conferences are lively events and their proceedings are an important source of information. 77.2.2.

Journals

Table 17.3 lists specialist journals on cosmetic subjects which consist of technical papers (original papers) and a review of them. Information retrieval on past technical papers published in journals is now generally retrieved from on-line computer systems which are described later, and reading such journals is a very effective way of collecting information on the latest trends in cosmetic technology on a day-to-day basis. The secondary documents of abstracts and indexes, are also very useful for this purpose. A major one is Table 17.3. Major cosmetic journals Journal 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) 16) 17) 18)

Cosmetics and Toiletries Drug and Cosmetic Industry Household Personal Products Industry (HAPPI) International Journal of Cosmetic Science Journal of Applied Cosmetology Journal of Society of Cosmetic Chemists Kosmetik International Parfums Cosmetiques Aromes Parfum and Flavorist Parfum und Kosmetik Soap, Cosmetics, Chemical Specialities Soap, Perfumery and Cosmetics Suffrages Journal of the Society of Cosmetic Chemists of Japan Journal of the Japanese Cosmetic Science Society Fragrance Journal C & T (cosmetics and toiletries journal) CIR (Cosmetic Information Research, Fragrance Journal Co.) (secondary document)

Publication frequency

Country

Monthly Monthly Monthly Bimonthly Quarterly Bimonthly Monthly Bimonthly Bimonthly Monthly Monthly Monthly Bimonthly Quarterly Quarterly Monthly Monthly

\]S. U.S. U.S. U.K. Italy U.S. Germany France U.S. Germany U.S. U.K. France Japan Japan Japan Japan

Monthly

Japan

Cosmetics and information 315 Table 17.4 Databases used in cosmetic research On-line information retrieval system

Database

Information available

Besides 12,000 journals JICST (scien- from Japan and other t i f i c / t e c h n i c a l countries, technical papers document files) in technical reports, conference proceedings, etc. JOIS JMEDICINE Papers published in major (files of mediJapanese medical journals cal papers from and those for related fields Japanese medi(life sciences, pharmacy) cal journals For Chemical Abstracts, the world's largest collection of abstracts ; contains technical information on CA SEARCH jourrals, single volume books, patents, conference proceedings from all over the world in chemistry and related areas. DIALOG Information on papers published in around 3,600 medical and biochemical MEDLINE journals from more than 70 countries. Produced by the U.S. National Library of Medicine Scientific and technical papers on cosmetics and fragrances ; most are from journals but there are DATA STAR KOSMET also some scientific conference and conference proceedings records.Produced by IFSCC.

Earliest tion

informa-

Providing organization or general agent

1975Japan Information Center for Science and Technology (JICST) 1981-

1967Knight-Ridder Information Inc. Maruzen Co., Ltd. K i n o k u n i y a Co., Ltd. Yusako Ltd., etc. 1966-

1985-

Knight-Ridder Information Inc. Maruzen Co,, ltd. K i n o k u n i y a Co., Ltd.

PATOLIS

Mainly information handled by the International Patents (P) Patent Documentation Utility models Center comprising patents, (U) utility models, designs, trademarks and patents from 56 other countries.

(P) Unexamined patent application .* 1971 Examined p a t e n t Japan Patents Inforapplication : 1955 mation Organiza(U) tion (JAPIO) Unexamined patent application : 1971 Examined p a t e n t application : 1960

DIALOG

C o m p r i s e s p a t e n t s in chemistry, electricity, machinery and all other areas of industry from all over the world. patent Particularly useful for investigating patent families Created by Derwent Publications.

Knight-Ridder Information Inc. Maruzen Co., Ltd. K i n o k u n i y a Co., Ltd. Yusako Ltd. Japan Technology Trading Co., Ltd.

WPI (World Index)

1963-

Note : Since 1992 it has been possible to use DIALOG to access INPADOC as well.

316 New cosmetic science

Section-62 - Essential Oils and Cosmetics in Chemical Abstracts (CA) (published biweekly). CA's CA-Selects, a temporarily bound edition of abstracts edited by computer according to theme is a great help in the ongoing task of information collection.

17.3. Databases As databases enable the necessary information to be retrieved instantaneously when it is required, their use is increasing rapidly. In Japan, on-line information retrieval systems were first inaugurated in the late 1970s and are now used by industry and scientific research institutions on a daily basis. And, with the expansion of personal computer communications, individual users can now access them freely. In this section, we look at the major databases used for cosmetic research. 77.5.7. Definition of a database Although a variety of definitions are used for a database depending on the person's viewpoint or standpoint, it is generally defined as "a collection of information files or data which have been sorted and integrated to facilitate processing by computers". In Japan, databases may simply be called files; there is no rigid distinction between these terms and both are much used. The major feature of databases is that they speed up the task of information collection, simplify it and make it more precise. Enabling constant access to the information relating to one's field of study and the areas relating to it, preventing duplications and information leaks and providing ideas for new technologies databases are very useful in research. 17.3.2, On-line information retrieval systems Through the use of communications circuits, on-line information retrieval systems enable information to be retrieved from a database in real time. Two of the major ones operated on a commercial basis are JOIS and DIALOG which enable access to many databases. The databases and information retrieval systems used frequently in cosmetics research are listed in Table 17.4. Let us say something briefly about KOSMET, a specialist cosmetic science database. KOSMET was produced by the IFSCC and can be accessed via Knight-Ridder Information's on-line information retrieval system Data Star. KOSMET became accessible via DIALOG in 1994. It contains information on cosmetic science and related areas (excepting patents) whose sources include technical journals, collections of scientific lectures and conference proceedings, and the information is updated every month. Information listings start from 1985 but in the case of papers presented at IFSCC conferences, material going back as far as 1968 may be accessed. In the years to come, as the volume of information continues to increase, more and more attention will surely be focused on KOSMET as a source of information on cosmetics.

Part II

1. Skin care cosmetics 2. Makeup cosmetics 3. Hair care cosmetics 4. Fragrance products 5. Body cosmetics 6. Oral care cosmetics

This Page Intentionally Left Blank

1

Skin care cosmetics

The skin can be said to be one of the body's organs. But, because we see it every day, it is not usually thought of as being very important. However, as is clear from the evolutionary history of living organisms, the skin has the very important function of preventing them and their cells from drying out by keeping the water which is so vital to life inside them. Some of the functions skin has are protecting the body from ultraviolet radiation using its melanin, regulating body temperature, and mitigating external stimuli through its neutralizing capability. The skin is the interface between the body and the external environment and it protects the body by responding to various changes in it. It is thus a very important organ for the body. The functioning of the skin and its mechanisms are upset by changes in the environment, and aging. It is the purpose of skin care cosmetics to keep the skin functioning properly and its mechanisms working well. So, ideal skin care cosmetics will protect the skin from the harmful effects of drying, ultraviolet radiation and oxidation; back up the skin's homeostasis function and keep it looking beautiful and healthyi-^\

1.1. Purposes, functions and roles of skin care cosmetics 7.7.7. Purposes of skin care cosmetics In our modern world, people benefit both from nature and the highly sophisticated environment they live in but they are also adversely affected by them. For instance, an air conditioner, by keeping the temperature under control, provides a comfortable environment to live in but it can cool the skin too much and cause it to dry out. Ultraviolet radiation can also affect the skin badly and this is now becoming better understood. For people living in such a sophisticated environment, the purposes of skin care cosmetics are considered to be as follows: (1) clean the skin (2) preserve the skin's moisture balance (3) stimulate skin metabolism (4) protect the skin from harmful ultraviolet radiation Formerly, skin care cosmetics were considered to just have 3 purposes but now it is normal to include the fourth because the idea of photoaging^^ has become accepted as the result of research that has been carried out in recent years. It goes without saying that skin care cosmetics must be designed to be excellent in terms of safety, stability, texture and usability based on thorough research and understanding of the physiological functions of the skin. 319

320

New cosmetic science

1.L2. Functions of skin care cosmetics Skin care cosmetics contain substances which enable the skin to function properly. They support its homeostasis function so that it is maintained in a beautiful and healthy condition or regains such a state if it is not. So, skin care cosmetics have many different functions. The basic ones are cleansing, anti-drying, ultraviolet damage prevention, antioxidation and invigoration but they can also clear up skin problems, have a whitening effect to combat skin aging-associated troubles (liver spots and freckles due to the sun's rays), prevent wrinkles, sagging skin and acne. However, these functions will only be manifested if the skin care cosmetics having them are used in an appropriate manner. It is therefore necessary to make a thorough consideration of their order of usage (beauty treatment system), season, the living environment, age, experience of using cosmetics and skin type of the user, preference regarding utility and occasion on use. Of the many types of beauty treatment systems on the market, the following are the major ones: (1) Basic care. Face cleansers (makeup removal, face washing) + lotions (moisture retention, humectant effect) + emulsions (moisture retention, humectant effect, provide oil, promote skin metabolism) and (2) Additional care. Essences, massage creams, packs, powders, etc. (special care) Additional care system products are designed to cover aspects not included in basic care products. 7.7.5. Roles of skin care cosmetics In accordance with the Japanese Pharmaceutical Affairs Law, skin care cosmetics may be defined fundamentally as products which cleanse the skin and moisturize the horny layer. However, the large amount of research that has been carried out on skin care cosmetics has found that they fulfill many other roles besides. Many studies have been done on the moisturizing mechanism of the skin. This mechanism can be broadly considered in terms of the horny layer and the dermis. In the horny layer, the natural moisturizing factor (NMF) which consists of amino acids, etc., sebum and skin surface lipids derived from epidermal oil components, are very important^^^. But in the dermis, it is hydrophobic substances such as phospholipids and macromolecular hydrophilic substances like hyaluronic acid, collagen and elastin that are considered to be important. If something goes wrong with the moisturizing mechanism at the horny layer level, it is essential to lighten the burden of the skin in order to make it healthy and beautiful again and this can be done by giving it a good balance of high quality oils and hydrophilic substances with great moisturizing capacity. So, when something goes wrong with the skin as a result of its homeostasis function not working properly, this must be corrected through the use of skin care cosmetics which are designed to redress the moisture balance. Stating their ideas concerning the moisture balance, Ozawa et al. said the following: "We have demonstrated that, at the horny layer level, NMF and lipid amounts decrease as the skin ages resulting in a reduction in its moisture retention capability leading to hardening of the horny layer. But we can make up for the reduction in moisture, NMF

Skin care cosmetics

321

Moisture balance

Fig. 1.1. Concept of moisture balance^'^"^\

and lipid occurring through aging by supplying equivalent substances (water, humectants and oils) in cosmetics to effect biological changes which will serve to regain homeostasis in the skin's moisture balance"^'^^^ (Fig. 1.1). It has been demonstrated that the surface condition can be improved and skin trouble prevented through the use of preparations combining water, humectant and oil in properly balanced proportions^^^'^^ In recent years, some spectacular research has been done on the usefulness of cosmetics (Refer to Part I-11 Usefulness of Cosmetics). This research has been showing clearly that they have a physiological action on the skin as well as a physical one and the evidence that skin care cosmetics restore homeostasis to the skin is showing us the direction in which cosmetic products must go in the future. To summarize the roles played by skin care cosmetics: they maintain homeostasis in the skin and restore it if it has been lost (keep the skin healthy and beautiful), delay aging in the skin, and provide a solution to skin problems. They must also be safe when used constantly over long periods. Much research has been done on changes in physiological parameters with aging. Some of theses are: (1) moisture retaining ability^'i^-^^) (2) sebum secretion function (3) horny layer turnover and horny layer cell area^^-^^) (4) changes in skin morphology (replica method) (5) horny layer viscoelasticity It goes without saying that the results of such research must be used to the full in the development skin care cosmetics. In the following, we will discuss the types, purposes, functions, main ingredients and production methods of typical skin care cosmetic products.

322 New cosmetic science

Table 1.1. Types of face cleansing cosmetic Product type

Surfactantbased type

Form (formula type)

Features

Solid (soap, transparent soap, neutral soap)

Main type of cleanser ; easy to use and feels good. ; but skin feels tight afterwards.

Cream • paste (cleansing foam)

Special face cleanser with excellent feeling and lather. It is easy to use. Bases may be selected in the range weakly acidic to alkaline depending on the purpose.

Liquid or viscous liquid type (cleansing gel)

Weakly acidic to alkaline. The weakly acidic base produces a weak cleanser but the alkaline base produces a strong one. The main type of cleanser for the hair and body.

Granule/powder form (cleansing powder, face powder) Aerosol type (shaving foam type, after type)

Easy to use. As they contain no water, papain or other enzyme may be incorporated.

There are two types-one which comes out like a shaving foam and the other as a gel which foaming becomes a foam on use (after-foaming type). A double container is used for the after foaming type.

Cream • paste (cleansing cream)

The emulsion type uses mainly the 0 / W emulsion. The type in which oils are made into a gel has high cleansing power. For heavy makeup.

Milky lotion (cleansing milk)

0 / W emulsion milky lotion. Lighter feeling after use than with cleansing cream. Easy to use.

SolventLiquid form based type (cleansing lotion)

Others

cleansing

Cleansing lotion. Contains large amounts of nonionic surfactants, alcohol and humectants. There is also a physical cleansing effect as it is wiped off with cotton wool. For light makeup.

Gel (cleansing gel)

The emulsion and liquid crystal types containing a lot of oils have high cleansing power and are rinsed off. They give a light feeling after rinsing off. The water soluble polymer gel type has low cleansing power.

Oil (cleansing oil)

Ingredients like surfactants and alcohol are added to the oil in small amounts. Rinsed off. When rinsed off forms 0 / W emulsion. Soft and moist feeling after use.

Pack (cleansing mask)

Peel-off mask employing water soluble polymers. Skin has strong feeling of being stretched. Removes dirt from skin surface and pores when peeled off. N. Naito et al : Fragrance Journal, No. 92, 1988

Skin care cosmetics 323

1.2. Face cleansing cosmetics i.2.7. Purposes and functions of face cleansing cosmetics The most important considerations to be made regarding face cleansing cosmetics, the first step in any cosmetic routine, are: (1) the object to be cleansed (skin surface) (2) the type of dirt adhering to the skin surface (3) the type of product to be used for the cleansing (4) the cleansing method Cleansing materials for clothes, dishes and other inanimate objects, should have as much cleansing and oil removing capability as possible but in the case of cleansing materials for the skin, a part of a living organism, it must be fully appreciated that it is undesirable to have excessive oil removing capability. The purpose of face cleansers is to remove skin metabolism products, such as sebum, horny layer flakes, sebum oxidation products and sweat residues, adhering to the skin; dirt and dust from the surrounding air; microorganisms; and in the case of women, makeup products as well. Modern cosmetic science has provided a large variety of face cleansing products which are designed to cope with variations in skin quality and type of dirt stemming from aging and differences in living environment, different face washing habits and preferences, as well as feel comfortable on the skin. In order to achieve a healthy and beautiful skin, it is very important to select the right face cleanser and use it in the proper manner. Face cleansers should thus remove substances which not useful or harmful to the skin and have no adverse effect on its tissues or substances which are useful to it. And, efforts should be made to supply useful substances to the skin through them. The different types of face cleansing cosmetic are listed in Table \.\^^\ They are divided into two types, a surfactant-based type containing a relatively large amount of surfactant which is used by placing on the palm of the hand and adding water to make a lather, and a solvent-based type which is mixed in with the dirt on the face and then wiped or rinsed off with water. In recent years, the functions of makeup products have been greatly enhanced, in particular their waterproof nature. However, this makes them very difficult to remove for face cleansing cosmetics so there are now special types of cleanser designed to remove particular types of makeup. Typical cleansing foams will be described in this section. For other types of cleanser, please refer to the relevant sections in other parts of Skin Care Cosmetics and Body Cosmetics. 7.2.2. Main ingredients of cleansing foams As they have surfactants such as fatty acid soap as their main ingredient, cleansing foams have great cleansing power. They also contain emollients (oils) and humectants to prevent excessive sebum loss. They are liked for and the feeling of moistness that they give and because there is none of the sensation of tightness in the skin which one gets

324 New cosmetic science Table 1.2. Main ingredients of cleansing foams Ingredient Soap (cleansing agent)

Typical raw materials Higher fatty acids

Ci2~Ci8 fatty acids, oleic acid, isostearic acid, 12-hydroxy stearic acid, plant and animal-derived fatty acids

Alkalis

Sodium hydroxide. Potassium hydroxide, triethanol amine

Amino acid surfactants (N-acyl glutamic acid salts), acylmethyl taurine, POE Other surfactants alkyl ether phosphate salts, glycerol fatty acid ester, POE glycerol fatty acid ester, POE alkyl ether, POE-POP block copolymer Emollients (oils)

Fatty acids, higher alcohols, lanolin derivatives, beeswax, jojoba oil, olive oil, coconut oil

Humectants

Sorbitol, multitol, polyethylene glycol (300, 400, 600, 1500, 4000), glycerin, 1,3butylene glycol, dipropylene glycol, propylene glycol, POE glucose derivatives

Others

Preservatives, Water soluble polymers. S c r u b b i n g granules, Chelating agents. Pharmaceutical agents

Ethyl paraben Sodium acrylate, cationic polymers, sodium alginate Low molecular weight polyethylene powder, nylon powder, etc. EDTA and its salts, sodium hexametaphosphate Sulfur, glycyrrhizinic acid salts, triclocarban

Colors, perfumes, antioxidants, purified water

from soap. They are a soft cream in form and are used by putting a small amount on the palm and then working it into a lather after adding water. Generally speaking, the alkali type cleansing foam which has fatty acid soap as its main ingredient produces a good lather, is easy to rinse off and gives a light feeling after use. This type can be made to give a feeling of moistness after it has been rinsed off by increasing the amounts of non-ionic surfactant and oils in the formula. However, during rinsing, the skin may feel clammy. There are also cleansing foams having amino acid surfactants as their main ingredients which feature weak acidity and low irritation; however the problem with them is their low foaming capability. The main ingredients of cleansing foams are listed in Table 1.2. 7.2.5. General manufacturing methods for cleansing foams The conventional method for making cleansing foams involved adding an oil phase in which fatty acids had been solubilized to a water phase in which alkalis had been solubilized to form fatty acid soap. However, with this method, it was easy for lumps to form, it took such a long time to dissolve them and it could cause a strange smell. In the method used nowadays, the water phase is normally added to the oil phase and it is possible to formulate much more fatty acid soap with it. However, using this method, an area of high viscosity forms during the addition of the water phase so equipment with high stirring power is required (Fig. 1.2). Low solubility and rises in viscosity inside the cooling equipment during cooling are two problems with A^-acylglutamic acid salts, the main ingredients of weakly acidic

Skin care cosmetics 325 Higher fatty acid Higher fatty alcoholEmollient (oil) Humectant Preservative

Oil phase

Water phase I(Py,^^^;.^d^^t^^T Alkalis —'

rStirring ^ Heating [Mixing J~] Dissolution | Strong stirring 70°C

" [Dissolution] Room temperature

Other surfactants • Chelating agent — Perfume Pharmaceutical agent Coloring agent

rStirringl

[MixingJ

1

[Deairing]

1

[Filtering]

I

[Cooling]

Fig. 1.2. Manufacturing process for soap-based cleansing foam.

cleansing foams, so it is necessary to take this into account when making such cleansing foams (Fig. 1.3). 1.2.4.

Types of cleansing

foam

(1) Higher fatty acid-based cleansing foams Typical formula 1. Soap-based cleansing foam Fatty acids:

Emollient: Alkali: Humectants: Surfactants: Preservative: Chelating agent: Perfume: Coloring agent: Purified water:

Stearic acid Palmitic acid Myristic acid Laurie acid Coconut oil Potassium hydroxide PEG 1500 Glycerin Glycerol monostearate ester POE (20) sorbitan monostearate

10.0 10.0 12.0 4.0 2.0 6.0 10.0 15.0 2.0 2.0 q.s. q.s. q.s. q.s. 27.0

Manufacturing procedure Heat the fatty acids, emollient, humectants and preservative together until melted and keep at 70°C (oil phase). Dissolve the alkali in the purified water and add this to the oil

326

New cosmetic science

f Purified waterHumectant Water phase Amino acid Type surfactant Chelating agent —

Oil phase

]_^ Heating_ Dissolution t 70°C

r Emollient (oil) — other surfactant y Preservative Perfume Pharmaceutical agentColoring agent

I. Heating—I Dissolution 70°C

"Stirring" Mixing

Stirring' Mixing [Deairing]

I

[Filtering]

I

[Cooling] Fig. 1.3. Manufacturing process for amino acid-based cleansing foam.

phase while stirring. Keep at 70° C until the neutralization reaction has finished. Heat the surfactants and dissolve the chelating agent, perfume and coloring agent and stir this into the mixture. Then de-air, filter and cool. The hardness of the finished product is greatly affected by the conditions under which it is cooled so the optimum conditions should be selected. Typical formula 2. Soap-based cleansing foam Fatty acids: Emollient: Alkali: Humectants: Surfactants: Chelating agent: Perfume: Purified water:

Stearic acid Myristic acid Laurie acid Jojoba oil Potassium hydroxide Sorbit (70% sorbitol solution) Glycerin 1,3-ButyIene glycol POE (20) glycerol monostearate ester Acylmethyl taurine

% 12.0 14.0 5.0 3.0 5.0 15.0 10.0 10.0 2.0 4.0 q.s. q.s. 20.0

Manufacturing procedure Heat the fatty acids, emollient and humectants together until melted and keep at 70° C (oil phase). Dissolve the alkali in the purified water and add this to the oil phase while stirring. Once the neutralization reaction has fully taken place, add the surfactants then the chelating agent and perfume. Then de-air, filter and cool.

Skin care cosmetics 327

(2) Amino acid-based cleansing foams Typical formula I. Weakly acidic cleansing foam Amino acid base surfactant: Humectants:

Other humectants:

Emollient: Preservative: Chelating agent: Perfume: Coloring agent: Purified water:

Sodium A^-acyl glutamate Glycerin PEG 400 Dipropylene glycol Acylmethyl taurine POE-POP block copolymer POE (15) oleyl alcohol ether Lanolin derivative

% 20.0 10.0 15.0 10.0 5.0 5.0 3.0 2.0 q.s. q.s. q.s. q.s. 30.0

Manufacturing procedure Dissolve the humectants in the purified water then add the sodium A^-acyl glutamate a little at a time so that lumps do not form (water phase). Add the chelating agent, heating and stirring to dissolve. While doing this, in a separate container, heat the emollient, other surfactants and preservative together to melt and add this to the water phase. Stir to mix; then add the perfume and coloring agent, mixing in well. De-air, filter and cool. A scrapered surface heat exchanger is normally used for the cooling of cleansing foams. In the case of amino acid-based cleansing foams, if the final temperature is lowered as much as possible, this will produce a highly stable product with uniform quality. Recently face cleansing cosmetics containing scrubbing granules have been developed with the objective of enhancing cleansing power or giving them the edge over competing products. Polyethylene, nylon and other resin powders, most of them having particle sizes in the range 20-1000 mm, are used as scrubbing granules.

1.3. Lotion 1.3.1, Purposes and functions of lotion Lotion is normally a transparent liquid cosmetic product which is applied to the skin for the purpose of cleansing and keeping it in a healthy condition. As well as cleaning the skin it also helps maintain its moisture balance. Until recently, the term lotion had just been applied to transparent liquids in which substances insoluble in water are solubilized to produce a stable solution by applying the principles of thermodynamics but there are now many types of lotion which do not fit this description. For example, there are transparent and semi-transparent lotions made using microemulsion and lipidnanosphere techniques, as well as opaque lotions that consist of an 0/W emulsion containing several percent oil, in which the specific gravities of the oil and water phases have been adjusted so that there is no creaming or sedimenta-

328 New cosmetic science Table 1.3. Different lotions and their purposes Type

Purpose

Softening lotion

Supplies moisture and humectants to the horny layer to make the skin soft and keep it feeling smooth and moist

Astringent lotion

Has astringent action as well as supplying moisture and humectants to horny layer. Inhibits sebum secretion. Gives light feeling on use and prevents makeup from spoiling.

Cleansing lotion

Used to remove light makeup or as a face skin cleanser. A lot of surfactant, humectant and alcohol are included in formulae to enhance the cleansing action on the skin.

Multi-layer lotion

Lotion consisting of 2 or more layers. Most have 2 layers which are either oil and water or water and powder. Unlike other lotions, they are shaken before use when they become either a milky lotion or a powder dispersion. A major one of this type is calamine lotion.

tion in such a low viscosity liquid. There are also transparent viscous liquid lotions containing water soluble polymers on the market. Lotions are used after the face has been cleaned using face cleansing cosmetics mainly to moisturize it and supply it with humectants. In order to provide the best feeling on use and moisturizing effect, the types and quantities of the humectants as well as the proportions of ethanol and oils are varied to suit the type and condition of the skin which depend on the age of the user and their living environment, different cosmetic routines and preferences. Different types of lotion are listed according to their purpose in Table 1.3. A brief description of microemulsions will now be given. In the narrowest sense, microemulsions can be thought of as being a transparent or semitransparent liquid phase formed from an oil, water and amphiphilic substance that, thermodynamically speaking, is a stable system through which a large, swollen micelle has been dispersed^^'^^^ In a broader sense, microemulsions also include thermodynamically unstable dispersions as well as transparent and semitransparent dispersions which are continually stable. (Refer to Section 7.1.3.) The biggest advantage of microemulsions over transparent solubilized systems is that much more emollient (oil component) can be incorporated in them which enables the stickiness of humectants and surfactants to be reduced. Another advantage is that they are clearly very distinct from transparent lotions in terms of external appearance. When devising formulae for them, attention must be paid to adjusting the HLB of surfactants. The effect of the emollient structure must also be considered. In general, it is easier to make adjustments with high polarity ones^^-^^^ 1.3,2. Main ingredients of lotions As has already been mentioned, the basic function of lotions is to supply moisture and humectants to the horny layer. Other types of ingredient are added for softness, astringency and cleansing effects depending on the purpose of the lotion. Table 1.4 lists the normal components of lotions.

Skin care cosmetics 329 Table 1.4. Components of lotions Component

Main functions

Typical raw materials

Amount added

Purified water

Supply moisture to horny layer Dissolution of ingredients

Ion exchange water

Alcohol

Light and cool feeling Bacteriostatic effect Dissolution of ingredients

Ethanol Isopropanol

Humectant

Glycerin, propylene glycol, dipropylene glycol, 1,3-butylene glycol, Maintains horny layer moisture polyethylene glycol (300, 400, 1500, 4000) and other polyhydric alcohols, Good feeling on use hyaluronic acid, multitol and other Dissolution saccharides, pyrrolidone carboxylate and other amino acid substances

Softening agent Emollient

Emollient effect on skin Humectant effect Good feeling on use

Ester oils Plant oils (olive oil, jojoba oil, etc.)

q. s.

Solubilizing agent

Solubilization of raw materials

High HLB surfactants (polyoxyethylene oleyl alcohol ether, etc.)

-1%

Buffer

Regulate product pH (skin pH balance)

Citric acid, lactic acid, amino acids, sodium citrate

q. s.

Thickening agent

Good feeling on use Humectant effect

Alginic acid salts, cellulose derivatives, quince seed gum, pectin, Pullulan, xanthan gum, magnesium aluminum silicate (veegum), carboxyvinyl polymer, acrylate polymers, sodium magnesium silicate (laponite)

-2%

Perfume

Give Perfume

Geraniol, Linalool, etc.

q. s.

Preservative

Prevent microbial tion

Methyl paraben, phenoxy ethanol

q. s.

Coloring agent

Coloring

Permitted colors

Anti-fading agent

Prevent fading, discoloration

Metallic ion sequestering agents, ultraviolet absorbents

q. s.

< Pharmaceutical agents > • Astringent • Bactericidal agent

Draw the skin together Disinfect skin

• Rejuvenating agent

Rejuvenate skin

Zinc sulfophenol, sodium sulfophenol Benzalkonium chloride salts, Photosensitiger Vitamin/amino acid derivatives, animal and plant extracts Glycyrrhizin derivatives, allantoin Placenta liquid, arbutin, kojic acid. Vitamin C derivatives

q. s.

contamina-

• Anti-inflammatory Prevent inflammation • Whitening agent Inhibit melanin formation

30--95%

-40%

-20%

Small amount

330

New cosmetic

science

1.3.3. General methods for manufacturing

lotions

Lotions are normally produced at room temperature. If they do not contain much alcohol or preservative and no heating is involved, special care is needed to prevent contamination by micro-organisms. First, humectants such as polyethylene glycol and 1,3-butylene glycol are added to the purified water and then the buffer, thickening agent, anti-fading agent and the other water soluble ingredients are dissolved in this (water phase). Next, the emollient, preservative, perfume, pharmaceutical agents and other ingredients which are soluble in ethanol or are oil soluble are added to ethanol together with a solubilizing agent (alcohol phase). The alcohol phase is then mixed together with the water phase and solubilization is allowed take place at room temperature. Subsequently, a coloring agent is added for toning purposes and then the mixture is filtered to obtain a very transparent lotion. Typical equipment used for filtering are filter paper and cartridges. If there is a lot of residue after filtering, it is necessary to revise the formula because this means that dissolution has not been complete (Fig. 1.4). There are now many non-alcohol lotions on the market as well. In this type of lotion, ingredients which are insoluble in water are dissolved in humectants together with solubilizers by heating. In this case, it is very important to select the right kind of humectant to obtain a transparent lotion (Fig. 1.5). For semitransparent lotions, microemulsion techniques are employed. However, they need more care than transparent lotions because particle size will vary tremendously depending on the surfactants and manufacturing processes used, which will in turn greatly affect the transparency (turbidity). 1.3.4. Types of lotion (1) Softening lotion. Though most of this type are weakly alkaline to weakly acidic, there Purified waterJ Humectant Water phase \ Buffer Anti-fading agent

Alcohol phase

Ethanol Preservative Perfume Solubilizer — Emollient —

-n

—^[Dissolution] — ^ Mixing Room temperature Solubilization

*- [Dissolution] — Room temperature

Coloring Toning

Coloring agent -

[Filtering] [Filling] Fig. 1.4. Process chart for lotion containing alcohol.

Skin care cosmetics 331

Water phase

Purified waterHumectant Buffer Anti-fading agent

Humectant (part o f ) y Preservative Non-aqueous phase I Perfume — (humectant part) Solubilizer Emolhent

• [Mixing]

—^[Dissolution] Room temperature

-*- Heating Dissolution 70°C

Mixing 1 Solubilization

Purified water Coloring Toning

Coloring agent

[Filling] -

I

[Filtering]

Fig. 1.5. Process chart for non-alcohol lotion.

are now many on the market whose pH has been adjusted to be close to that of the skin surface, i.e. pH 5.5-6.5. The ability of a softening lotion to give a particular sensation on use and to supply moisture and humectants to the horny layer (the fundamental purposes of a lotion) is determined by such factors as the amount, types and combinations of humectants in them, the presence or absence of water soluble polymers and the amount of ethanol. Also, as emollients, even in very small amounts, have such a great effect on texture, it is of great importance to consider their incorporation through the use of solubilization and microemulsion techniques. Typical formula 1. Transparent lotion (weakly acidic) Humectants: Emollient: Surfactants: Alcohol: Perfume: Coloring agent: Preservative: Anti-fading agent: Buffer: Purified water:

1,3-butylene glycol Glycerin Oleyl alcohol POE (20) sorbitan monolaurate POE (15) lauryl alcohol ether Ethanol

% 6.0 4.0 0.1 0.5 0.5 10.0 q.s. q.s. q.s. q.s. q.s. 78.9

Manufacturing procedure Dissolve the humectants, buffer and anti-fading agent in the purified water at room temperature to make the water phase. Then dissolve the preservative, perfume, emollient and solubilizers (surfactants) in the ethanol and solubilize this in the water phase. Finally, add the coloring agent for toning, filter and put into containers.

332 New cosmetic science Typical formula 2. Softening lotion with thickening agent Humectants: Surfactant: Thickening agents:

Sorbit Dipropylene glycol PEG 1500 POE (20) oleyl alcohol ether Methyl cellulose Quince seeds

Ethanol: Perfume: Coloring agent: Preservative: Chelating agent: Anti-fading agent: Buffer: Purified water:

% 4.0 6.0 5.0 0.5 0.2 0.1 10.0 q.s. q.s. q.s. q.s. q.s. q.s. 74.2

Manufacturing procedure Dissolve the chelating agent in some of the purified water and stir the methyl cellulose and quince seeds (polymer thickening agents) into this to form a viscous liquid. Then make a solution of the humectants, buffer, anti-fading agent in the remaining purified water at room temperature and add the viscous liquid to this to make a uniform aqueous solution. Dissolve the preservative, surfactant and perfume in the ethanol and solubilize this in the aqueous solution. Add the coloring agent to tone and then filter. Typical formula 3. Semitransparent

microemulsion

lotion

1,3-butylene glycol Glycerin PEG 4000 Olive oil POE (20) sorbitan monostearate POE (5) oleyl alcohol ether

Humectants: Emollient: Surfactants: Ethanol: Perfume: Coloring agent: Preservative: Buffer: Anti-fading agent: Purified water:

6.0 5.0 3.0 0.5 1.5 0.3 10.0 q.s. q.s. q.s. q.s. q.s. 73.7

Manufacturing procedure Dissolve the humectants, anti-fading agent and buffer in the purified water at room temperature (water phase). Then dissolve the emollient, surfactants, preservative and perfume in the ethanol also at room temperature (alcohol phase). Add the alcohol phase to the water phase and form the microemulsion. (2) Astringent

lotion. Astringent lotion prevents the secretion of excessive sebum and

Skin care cosmetics

333

sweat by drawing skin proteins together and it generally gives a very light feeling. It is thus intended for people with oily skins and for summer use. However, in recent years, the purposes of this type of lotion have become more clearly defined, i.e. to inhibit sebum secretion and prevent makeup from spoiling. As a result of this, the general name of astringent lotion is in the process of changing to such names as toning lotion and oil control lotion. Astringent lotion is acidic, the large amount of alcohol in it temporarily lowers the temperature of the skin by taking heat from it when it evaporates and it contains pharmaceutical agents like sulfophenol salts and vitamin B^ hydrochloride. Recently, astringent lotions specially for inhibiting the secretion of sebum in the T zones of the face (forehead and the nose) where it is profusely secreted have come on to the market. These lotions produce a very special feeling when used due to the very large amount of alcohol that they contain. Typical formula 1. Astringent lotion Humectants: Surfactants: Astringents: Ethanol: Perfume: Preservative: Buffer: Coloring agent: Anti-fading agent: Purified water:

Dipropylene glycol Sorbit POE (20) oleyl alcohol ether Zinc sulfophenol Citric acid

% 1.0 1.0 1.0 0.2 0.1 15.0 q.s. q.s. q.s. q.s. q.s. 81.7

Manufacturing procedure Dissolve the humectants, astringent, buffer and anti-fading agent in the purified water at room temperature (water phase). Then dissolve the perfume, surfactant and preservative in the ethanol (alcohol phase), and solubilize the alcohol phase in the water phase. Add the coloring agent for toning, filter and put the product in containers. (3) Cleansing lotion. This type of lotion is used for removing light makeup or for cleansing the face in the morning before putting on makeup. In order to enhance the cleansing effect, a lot of surfactants and ethanol are included in the formula. The careful selection and combination of humectants is also important for this. Dirt is removed from the face by applying the lotion to some cotton wool and wiping it off so there is a physical cleansing action as well as a chemical one. The problem with cleansing lotion, however, is that if the cleansing effect is required to be further enhanced by using more surfactants, it becomes sticky and does not feel good with use so it is intended purely for removing light makeup and there is not much room for enhancing its cleansing power. Other cleansing cosmetics such as high cleansing power creams and gels must therefore be used to remove heavy makeup. Cleansing lotion is good for people who do not like to use soap or cleansing foams because their skin is sensitive or those who desire convenience in removing makeup.

334 New cosmetic science Typical formula 1. Cleansing lotion containing Humectants: Solubilizer: Detergent:

alcohol

Dipropylene glycol 1,3-butylene glycol PEG 400 POE (20) sorbitan monolaurate Polyoxyethylene-polyoxypropylene block copolymer

Ethanol: Perfume: Preservative: Buffer: Coloring agent: Anti-fading agent: Purified water:

% 6.0 6.0 6.0 1.0 1.5 15.0 q.s. q.s. q.s. q.s. q.s. 64.5

Manufacturing procedure Dissolve the humectants, buffer and anti-fading agent in the purified water at room temperature (water phase). Then dissolve the solubilizer, detergent, perfume and preservative in the ethanol (alcohol phase). Solubilize the alcohol phase in the water phase. Add the coloring agent for toning, filter and put the product in containers. (4) Multi-layer lotion. This type of lotion consists of two or more layers. There is a liquid-liquid system comprising oil and water layers and a liquid-solid system comprising water and powder layers, both of which are shaken when used. If small amounts of surfactants are added to the liquid-liquid system type it becomes a milky lotion when used. This makes it easier to use, expands its range of purposes and enables it to give a particular sensation. Replacing the surfactants with powders enables one to make a product which will become a uniform powder emulsion when shaken. The typical example of the liquid-solid system is calamine lotion. It is good for summer use because it relieves the burning sensation from sunburned skin. In addition to the cool, light feeling calamine lotion gives, the powder in it adsorbs sebum so it is also effective in preventing makeup from spoiling. Typical formula 1. Two layer lotion Oil: Humectants: Surfactant: Ethanol: Perfume: Preservative: Coloring agent: Purified water:

Squalane Sorbit Glycerin POE sorbitan tetraoleate

% 8.0 1.0 1.0 0.2 10.0 q.s. q.s. q.s. 79.8

Skin care cosmetics 335 Manufacturing procedure Add the oil-soluble coloring agent to the squalane. Dissolve the POE sorbitan tetraoleate and preservative in the ethanol and add this to make the oil phase. Dissolve the sorbit, glycerin and water soluble coloring agent in the purified water to make the water phase. Then add the alcohol phase to the water phase at room temperature and filter through a nylon or other filtering material, stirring well, to make the finished product. Typical formula 2. Calamine lotion (liquid-solid system) Ethanol: Humectants: Powders: Pharmaceutical agents: Perfume: Anti-fading agent: Purified water:

Glycerin 1,3-butylene glycol Iron oxide (red) Zinc oxide Kaolin Camphor Phenol

% 15.0 2.0 2.0 0.15 0.5 2.0 0.2 0.02 q.s q.s. 78.13

Manufacturing procedure Dissolve the humectants and perfume in the ethanol (alcohol phase). Dissolve the camphor and phenol in the purified water, then mix in the powders, anti-fading agent and alcohol phase ensuring the wetting and dispersion of the powders. Filter through a 150 mesh filter to make the finished product.

1.4. Milky lotions L4.L

Purposes and functions of milky lotions

Milky lotions have a character which is intermediate to that of lotions and creams. With the exception of special types, they are emulsions which contain little oil and have high fluidity. We have already mentioned that skin care cosmetics maintain homeostasis in the skin and help it to recover from skin troubles as well as some of the other roles they perform. Milky lotions play a role in this by maintaining the skin's moisture balance mainly by supplying it with water, humectants and oils to keep it moist and supple. In addition to products with these basic functions, there are a variety of others which make use of the special characteristics of milky lotions. The purposes and functions of milky lotions are listed in Table 1.5. Milky lotions contain a much larger proportion of aqueous components than oily ones, so they have a close affinity with the skin and spread well over it. As they are not oily and give a light feeling, milky lotions are good for summer use and suited to skin types from normal to oily.

336

New cosmetic

science

Table 1.5. Purposes and functions of milky lotions

Purpose • function Moisturizing/softening the skin

Stimulate skin circulation/increase softness Cleansing/makeup removal UV protection"°^^' (daily use sun protection products) Others (refer to the relevant sections) Ultraviolet protection Under makeup cream Soften horny layer Protect hair For the body and hands

Product category Emollient lotion (Have such names as Moisture Lotion, Milky Lotion, Nourishing Lotion, Nourishing Milk, Skin Moisture and Moisture Emulsion. The emulsion type, oil and humectant amounts and other factors are adjusted to suit the season, different skin types and user preferences) Massage Lotion Cleansing lotion Sun Protect (Called such names as Protect Emulsion, Sun Protector, UV Care Milk) Sunscreen Makeup Lotion Horny Layer Smoother Elbow Lotion Hair Milk Hand Lotion Body Lotion

Note : When engaging in sports and leisure activities, sunscreen products with high SPF ratings are used to protect the skin from strong UV radiation. Among skin care cosmetic products, there are also daily use sun protection products to protect the skin from the UV exposure we get when engaging in everyday activities, like doing the laundry, shopping and walking around. As well as preserving the skin's moisture balance such products also function as under makeup creams.

Milky lotions employ dispersions of liquids which, like oil and water, are mutually insoluble in each other. Milky lotions are thermodynamically unstable emulsion systems. Stokes law expresses the relationship between the separation of the dispersion phase (emulsion particles) from the dispersion medium (continuous phase)^^) (Refer to Part 1.7). The following are examples of measures which should be taken to maintain the stability of the system: (1) make the emulsion particles very fine; (2) reduce the difference between the specific gravities of the internal and external phases; or (3) raise the viscosity of the external phase. With this in mind, such methods as thickening the dispersion medium using water soluble polymers and clay minerals or giving the emulsion particles a protective colloid character are often used to enhance stability as well as improve texture. The pH of most milky lotions is made weakly acidic to neutral to fit in with the pH range of the skin's surface. The pH of a special type for softening the horny layer on the elbows and heels is alkaline. Table 1.6 shows a classification of the different types of formulae for milky lotions according to emulsion type and oil amount.

Skin care cosmetics 337 Table 1.6. Types of milky lotion formulae and products

Emulsion type

Oil amount

Emulsifier Soap (higher fatty acid soap) Soap + non-ionic surfactant

A 1

Non-ionic surfactant Water soluble polymer (polymer emulsification)

I

Protein-based surfactant (protein emulsification)

Organically modified clap minerals

Non-ionic surfactant

3-30

Emollient Lotion Sun Protect Hand Lotion

10-50

Cleansing Lotion, Emollient Lotion

10-40

1

Massage Lotion. Elnollient Lotion Emollient Lotion

10-10

Massage Lotion

Non-ionic surfactant

Multiple emulsion

Typical products

30-50

I/

-

II

Emollient Lotion (There are two types of emulsion-Wl O/W and O/W/O. There are hardly any multiple emulsion products on the market because there are many stability problen~swith them.)

/

1.4.2. Main ingredients of milky lotions Many of the ingredients of milky lotions are similar to those of creams but the proportion of solid oils and waxes is much less in milky lotions. Virtually all employ the O/W type emulsion but the WIO type is also used for certain special products and applications. The surfactants used for emulsification are mostly the non-ionic and anionic types which are highly safe. Nowadays, however, there are also biological emulsifiers in the form of protein-based surfactants. Oily ingredients used comprise hydrocarbons, oils, waxes, higher fatty acids, higher alcohols and esters, as well as straight chain and cyclic silicone oils, which have come into use recently. The types and quantities of such oily ingredients to be used are determined in consideration of desired texture and stability characteristics. Examples of aqueous ingredients used are purified water, ethanol, polyhydric alcohols and water soluble polymers. Other ingredients used include preservatives, pharmaceutical agents, chelating agents, ultraviolet absorbents, anti-oxidants, dispersants, anti-fading agents, buffers, coloring agents, utility enhancers and perfumes. Formulae for milky lotions should be designed with consideration for the features desired in the product, as well as on the basis of a good understanding of a wide range of characteristics for each ingredient, such as stability, safety, preservation and texture. For a list of the main ingredients generally used in milky lotions, refer to Section 1.5.2, Table 1.9 Main components of creams.

338 New cosmetic science Purified water — Humectant Chelating agent Alkalis Coloring agent -

Water phase

Oil phase

*- Heating Dissolution 60-70°C

-• [Emulsification]

Heating Dissolution 60-70°C

Heating Oil (includes higher Dissolution 70-75X fatty acids) Surfactant Pharmaceutical agent UV absorbent Preservative Perfume

Stirring]Mixing_ 60—70°C Emulsification equipment [Deairing] [Filtering] [Cooling]

I I

[Storage]

Pharmaceutical agent(water soluble)

[Filling]

Fig. 1.6. Process chart for OAV type milky lotion employing soap and non-ionic surfactant.

1.4.3. General manufacturing methods for milky lotions Heating processes are often employed in the manufacture of milky lotions to prevent contamination by microorganisms and facilitate emulsification. The manufacturing process for milky lotions has many steps in common with that for creams but, in the case of milky lotions, it is very important to select the proper conditions for such items as the emulsification (procedure for adding materials, emulsification temperature, order of addition), stirring, emulsification equipment and cooling process because the viscosity and other physical properties are greatly affected by such manufacturing conditions. In the actual manufacturing process, after adding the dispersion phase to the disperf Purified water Humectant Water phase Chelating agent Coloring agent -

Oil

Oil phase

Heating Dissolution 70-75°C

Stirring Heatmg _^ [Emulsification]-i- [Neutralization]— Mixing Dissolution 60-70°C t 60-70X 60-70°C Emulsification equipment

Heating Dissolution 60-70°C

Surfactant Pharmaceutical agent UV absorbent Preservative Perfume Thickening agent (1% solution)Alkalis (to neutralize thickening agent)

I I

[Deairing] [Filtering] [Cooling] [Storage]

1

[Filling]

Fig. 1.7. Process chart for OAV type milky lotion employing non-ionic surfactant and carboxyvinyl polymer.

Skin care cosmetics 339 sion medium and carrying out the preliminary emulsification, the emulsion particle size is made uniform using powerful emulsification equipment (Homomixer, Eppen-Bach Mixer); then the emulsion obtained is de-aired, filtered and cooled using a heat exchanger to produce the finished product (Figs. 1.6, 1.7). 1.4 A.

Types of milky

lotion

1.4.4.1. Moisturizing and softening milky lotion Most of the milky lotions of this type are the 0 / W emulsion type and contain 10-20% oil and 5-15% humectant. Typical formula 1. Emollient lotion (0/W emulsion, soap and non-ionic Oil component:

Surfactant: Humectants: Alkali: Preservative: Perfume: Purified water:

Stearic acid (partly transformed into soap after reaction) Cetyl alcohol Petrolatum Squalane Glycerol-tri-2-ethyl hexanoate Sorbitan mono-oleate Dipropylene glycol PEG 1500 Triethanol amine

surfactant)

2.0 1.5 4.0 5.0 2.0 2.0 5.0 3.0 1.0 q.s. q.s. 74.5

Manufacturing procedure Add the humectants and alkali to the purified water and heat to 70°C (water phase). Make a solution of the oil component ingredients, add the surfactant, preservative and perfume and heat to 70°C (oil phase). Add the oil phase to the water phase and carry out the preliminary emulsification. After making the emulsion particle size uniform using a Homomixer, de-air, filter and cool. Typical formula 2. Emollient lotion (O/W emulsion employing thickening agent, nonionic surfactant) % Oil component: Cetyl alcohol 1.0 Beeswax 0.5 Petrolatum 2.0 Squalane 6.0 Dimethyl polysiloxane 2.0 Alcohol: Ethanol 5.0 Humectants: Glycerin 4.0 1,3-butylene glycol 4.0 Surfactants: POE(10)mono-oleate 1.0 Glycerol monostearate 1.0 Thickening agent: 20.0 Quince seed extract (5% aqueous solution)

340 New cosmetic science Preservative: Coloring agent (dye): Perfume: Purified water:

q.s. q.s. q.s. 53.5

Manufacturing procedure Add the humectants and coloring agent to the purified w^ater and heat to 70° C (water phase). To a solution of the oil component ingredients, add the surfactants, preservative and perfume and heat to 70°C (oil phase). Add the oil phase to the water phase and carry out the preliminary emulsification; then add the quince seed extract and ethanol and stir. After making the emulsion particle size uniform using a Homomixer, de-air, filter and cool. Typical formula 3. Cleansing lotion (0/W emulsion incorporating thickening agent, nonionic surfactant) % Oil component: Stearyl alcohol 0.5 Hardened palm oil 3.0 Liquid paraffin 35.0 Humectants: Dipropylene glycol 6.0 PEG 400 4.0 Surfactants: Sorbitan sesquioleate 1.6 POE(20)oleyl alcohol ether 2.4 Thickening agent: Carboxyvinyl polymer (1% aqueous solution) 15.0 Alkali: Potassium hydroxide 0.1 Preservative: q.s. Chelating agent: q.s. Perfume: q.s. Purified water: 32.4 Manufacturing procedure Add the humectants and chelating agent to the purified water and heat to 70° C (water phase). Heat the oil component ingredients together to make a solution, add the surfactants, preservative and perfume and keep heating to 70°C. Add this to the water phase to carry out the preliminary emulsification. Add the carboxyvinyl polymer aqueous solution and stir; then add an aqueous solution of the alkali and stir again. After making the emulsion particles uniform using a Homomixer, de-air, filter and cool. Typical formula 4. Emollient lotion (W/0 emulsion, non-ionic Oil component:

Humectant: Surfactants:

Microcrystalline wax Beeswax Lanolin Liquid paraffin Squalane Propylene glycol Sorbitan sesquioleate POE(20)sorbitan mono-oleate

surfactant) % 1.0 2.0 2.0 20.0 10.0 7.0 4.0 1.0

Skin care cosmetics 341 Preservative: Perfume: Purified water:

q.s. q.s. 53.0

Manufacturing procedure Add the humectants to the purified water and heat to 70°C (water phase). Heat the oil component ingredients together to make a solution, add the surfactants, preservative and perfume and keep heating to 70° C. Stirring, add this gradually to the water phase to carry out the preliminary emulsification. After making the emulsion particles uniform using a Homomixer, de-air, filter and cool.

1.5. Creams Like lotions, creams are a skin care cosmetic which have been in general use since way back in history. In parallel with advances in emulsification techniques and changes in beauty treatments, many different types of cream have been made throughout history and the great variety of creams that are being made today are the result of advances in surface chemistry, higher level cosmetic production techniques and the development of new beauty treatments. 1.5.1. Purposes and functions of creams Creams are a type of emulsion in which two liquids that do not mix together, like water and oil, are made into a stable dispersion by making one the dispersion phase and dispersing it through the other which acts as the dispersion medium. Being semi-solid, creams are stable over a wider range of conditions than milky lotions and oils, and humectants and water can be included in a greater range of proportions. Because of this they occupy a very important position among skin care cosmetics. Table 1.7. Purposes and functions of different creams Purpose/function

Product type

Moisturizing and softening action

Emollient creams (Nutrient Cream, Nourishing Cream, Moisture Cream, Vanishing Cream, Night Cream, etc. in which the emulsion type, amount of oil and humectant are varied to cater to the season, skin type, preference, etc.) Stimulate circulation, soften skin Massage Cream Cleansing, makeup removal, etc. Cleansing Cream Under makeup cream, makeup base Makeup Cream, Base Cream, Pre-makeup Cream Other specific purposes e.g. : UV protection Depilatory action Hairstyling Deodorant Shaving Horny layer softening

Sunscreen Cream, Suntan Cream Hair Remover Hair Cream Deodorant Cream Shaving Cream Horny Layer Softening Cream

342 New cosmetic science

Generally speaking, the main functions of creams are to maintain the moisture balance and keep the skin moist and supple through the supply of water, humectants and oils. In addition to creams which moisturize the skin and make it more supple, there are many others which have the additional functions of stimulating the circulation, cleansing the skin and removing makeup (Table 1.7). As creams are so easy to use and apply to the skin and such a wide range of formulations is possible for them, they can be made to feel light on use, slightly oily, hard or soft, give a moist feeling, spread well, easily penetrate the skin, be easy or difficult to wipe off and be capable or incapable of being rinsed off with water. It is easy to vary the amount of water, and the amount and type of humectant and oil in the formulation to suit different purposes of use in order to cater to different skin types, skin conditions, cosmetic routines and preferences which vary with the season, age of the user and living environment. Creams are classified according to formulation (emulsion type, oil amount) in Table 1.8. 7.5.2. Main ingredients of creams Some of the main ingredients of creams are oily ingredients, aqueous ingredients, surfactants, preservatives, chelating agents, perfumes and pharmaceutical agents. As there are so many different combinations of them, we will only be discussing the major ones here. Table 1.8. Formulations of different creams Main ingredients Cream type

Oilphase proportion

Emulsifier

Typical example Typical products

Former naming

(%)

10-30

0 / W Type

30-50

• • • • •

Higher fatty acid soap Non-ionic surfactant Protein-based surfactant Soap + non-ionic surfactant Beeswax + borax + non-ionic surfactant

50-85 20—50

W/OType

50-85

Anhydrous oily type

100

• Non-ionic surfactant • Amino acid + Non-ionic sur factant (amino acid gel emulsification) • Organically modified clay min eral • Soap + non-ionic surfactant • Oily gelling agent

Emollient Cream

Product with 10— 20% oil phase and soap as the main emulsifier, called Vanishing Cream

Emollient Cream

Medium Cream

Massage Cream, Cleansing Cream, Emollient Cream

Cold Cream

Emollient Cream Massage Cream, Cleansing Cream, Emollient Cream

Liquefying Cream (Cleansing Cream)

-

Cold Cream

—

Skin care cosmetics 343 Creams are either O/W or W/O emulsions whose special features are provided by the surfactants and oily ingredients used in them. In the case of the O/W type, hydrophilic surfactants are used in the main. The oily ingredients used can vary widely from those with no polarity to those with very high polarity. In the case of creams with a high internal phase proportion, the cream state is achieved when the structural fluidity disappears as a result of a rise in the density of the emulsion particles. However, when the internal phase ratio is low, in order to achieve a degree of firmness, it is necessary to add such amphiphilic substances as higher alcohols and higher fatty acids so that the fluidity of the external phase disappears and the stability of the cream state is enhanced. Higher alcohols are the amphiphilic substances normally used. It has been shown that if they are used in combination with non-ionic surfactants, lamellar liquid crystals form in the external phase (water phase) which makes a gel structure in it^^-^°). To make this type of cream become more stable with time it is very effective to use cetyl alcohol together with stearyl alcohoF^^^^^ For the W/O emulsion cream, the lipophilic surfactant is the main type used. Oily ingredients used comprise mainly the non-polar type. In order to raise stability, it is important to prevent sedimentation in the internal phase (water phase) and to do this it is necessary to take care in the selection and combination of oils. In the case of creams which have a lot of oil phase, the W/O emulsion has been used to increase the oily nature and the O/W type when a light feeling is desired. The emulsion type may be freely selected in this way only when there is a lot of oil component, as in the case of cold creams' and cleansing creams. As a result, virtually all creams which have little oil component have been limited to the O/W emulsion. However, as will be described later, as a result of new developments in emulsification techniques, it is now possible to obtain creams with a light feeling on use and excellent water resistance even when there is relatively little oil component. Typical major ingredients of creams are shown in Table 1.9. As a result of recent advances made in chemical synthesis and refining techniques, many more oils, humectants, emulsifiers and pharmaceutical agents are now being used. 1.5.3. General manufacturing methods for creams The humectants and other water phase ingredients are added to the purified water and this is heated to 70° C to make the water phase. Then the oil phase is prepared by making a solution of the solid oils, semi-solid oils, liquid oils, preservative and antioxidant, heating and stirring this at 70°C. The perfume is stirred into the oil phase just before emulsification. The oil phase is then stirred into the water phase gradually to carry out the preliminary emulsification. Next, this mixture is processed in an emulsification appa^ Cold cream has a very long history dating back to Roman times. It is used for a wide range of purposes such as removing dirt and supplying a suitable amount of oil to the skin. It has been called cold cream since long ago because of the cool sensation it gives when the moisture in it evaporates from the skin. It is an oily cream containing water, existing in an emulsion state with a high oil phase content (particularly hydrocarbon oils). As its hardness depends greatly on the temperature, it is necessary to ensure that it does not become very soft or hard when the temperature is high or low. The emulsion is either the W/O type or the O/W type.

344 New cosmetic science Table 1.9. Main components of creams Components

Typical raw materials

Oil phase components

(Hydrocarbons) squalane, liquid paraffin, petrolatum, solid paraffin, microcrystalline wax, ceresin, etc. (Fats and oils) olive oil, almond oil, cocoa butter, macadamia nut oil, avocado oil, hardened palm oil, castor oil, sunflower oil, evening primrose oil, synthetic triglycerides, etc. (Waxes) beeswax, lanolin, carnauba wax, candelilla wax, jojoba oil, etc. (Fatty acids) stearic acid, oleic acid, isostearic acid, myristic acid, palmitic acid, behenic acid, etc. (Higher alcohols) cetanol, stearyl alcohol, behenyl alcohol, hexadecyl alcohol, octyldodecyl alcohol, cholesterol, etc. (Synthetic esters) IPM, glycerin triester, pentaerythritol tetraester, cholesteryl ester, etc. (Others) Siliconeoil (dimethyl polysiloxane, methylphenyl polysiloxane, cyclomethicone), etc.

Water phase components

(Humectants) glycerin, propylene glycol, sorbit, polyethylene glycol, dipropylene glycol, 1,3-butylene glycol, diglycerin, mannitol, POE methyl glycoside, biopolymers, etc. (Thickening agents) quince seeds, pectin, cellulose derivatives, xanthan gum, sodium alginate, carrageenan, carboxyvinyl polymer, etc. (Alcohols) ethanol, isopropyl alcohol (Purified water) ion exchange water

Surfactant (emulsifier)

(Non-ionic) glycerin monostearate, POE sorbitan fatty acid esters, sorbitan fatty acid esters, POE alkyl ether, POE-POP co-block copolymer, POE-hardened castor oil ester, etc. (Anionic) fatty acid soaps, sodium alkyl sulfate, etc.

Others

(Alkalis) potassium hydroxide, sodium hydroxide, triethanol amine (Perfumes) (Colorants) permitted colors, pigments (Chelating agent) EDTA (Preservatives) parabens, sorbic acid, isopropylmethyl phenol, etc. (Antioxidants) dibutyl-hydroxytoluene, vitamin E, etc. (Buffers) citric acid, sodium citrate, lactic acid, sodium lactate, etc. (Pharmaceutical agents) vitamins, UV absorbents, amino acids, whitening agents, etc.

ratus (Homomixer) to make the emulsion particles uniform, whereupon it is de-aired, filtered and cooled. It is then transferred to a storage tank and put into containers. This is the general method for manufacturing an OAV emulsion type cream (Fig. 1.8). In the case of the W/0 type cream, the order of addition is the reverse of that for the 0/W type, with the water phase being added gradually to the oil phase to carry out the preliminary emulsification. The process from here on is the same as that for the O/W type (Fig. 1.9). In the manufacturing of a cream, the processes which affect the quality characteristic values the most, in particular the hardness, are the process for adjusting the emulsion particle size and the cooling process. The scrapered surface heat exchanger used in the cooling process is very important for obtaining a cream with stable quality. When using

345

Skin care cosmetics

\AT , u \ Purified water Water phase [ Humectant

Oil phase

» * [Heat] — r — [Preliminary ^ about ^^^nt 70°C 7n°r ' i.:^:.„.:„„i emulsification] about 70°C

Fats, waxes Liquid oil Surfactant Preservative

[Emulsification] „u„... ^no^ about 70°C

- [Deairing]

I

[Filtering]

I

- Heating dissolution • 70-80°C

•• Stirring — about 70°C

[Cooling] * [Storage]

I

Perfume -

[Filling]

*Homomixer used **Heat exchanger used Fig. 1.8. Process chart for OAV type cream.

this type of cooling equipment, it is necessary to pay attention to the setting of the cylinder rotation speed and the final temperature. 1.5.4. Types of cream (1) Vanishing cream. Vanishing cream has this name because it appears to vanish when spread on the skin. Explained briefly, vanishing cream is an emulsion of water and stearic acid (and higher alcohols, stearic acid monoglycerides, etc.). To give it a moisturizing effect, polyhydric alcohols (glycerin, sorbit, propylene glycol, polyethylene glycol, etc.) are added. It employs the 0/W type emulsion only with a 10-20% oil phase being dispersed through the water phase and has been one of the major types of cream for many years. Water phase

Oil phase

Purified waterHumectant

Fats, waxes Liquid oil Surfactant Preservative

J

- [Heat] — about 70°C

—i-Heating/Dissolution—j-^ Stirring —*-—[Preliminary—i-[Emulsification] about 70°C emulsification] 70-80°C about 70°C [Deairing]

I

1

[Filtering]

Perfume •

I

[Cooling]

I

[Storage]

1

[Filling] Fig. 1.9. Process chart for W/O type cream.

346 New cosmetic science When the stearic acid in the oil phase and the potassium hydroxide (it could also be sodium hydroxide or triethanol amine) in the water phase mix, there is a neutralization reaction producing potassium stearate which acts as an emulsifier. This is called reaction emulsification (soap emulsification) and is a manufacturing method which has been widely used. However, with the introduction of surfactants, there are now many vanishing creams made using a combination of reaction emulsification and surfactants. Nowadays, as the pH of creams is close to neutral, the main type of emulsion system used is one using mainly non-ionic surfactants together with a small amount of soap. Typical formula 1. Vanishing cream (O/W type; soap and non-ionic Oil component:

Humectant: Surfactant: Alkali: Preservative: Antioxidant: Perfume: Purified water:

surfactant) % 8.0 4.0 6.0 5.0 2.0 0.4 q.s. q.s. q.s. 74.6

Stearic acid Stearyl alcohol Butyl stearate Propylene glycol Glycerin monostearate Potassium hydroxide

Manufacturing procedure Add the humectant and alkali to the purified water and heat to 70° C to make the water phase. After heating the oil component ingredients together to make a solution, add the surfactant, preservative, antioxidant and perfume and keep heating to 70° C. Add this to the water phase to carry out the preliminary emulsification. After making the emulsion particles uniform in size in a Homomixer, de-air, filter and cool. (2) O/W-type medium cream. Most emollient creams (nourishing cream, night cream, moisture cream) are of this type. Having an oil phase of 30-50%, the character of this type of cream is midway between that of vanishing cream and cold cream which is why it is called medium cream. This is an extremely useful type of cream as, because its low oil content, it gives a light feeling and both oil soluble and water soluble pharmaceutical agents can be included in the formula. Typical formula 1. Emollient cream (O/W type; non-ionic Oil component:

Humectant: Surfactant: Preservative:

Stearyl alcohol Stearic acid Hydrogenated lanolin Squalane Octyldodecanol 1,3-butylene glycol PEG 1500 POE (25) cetyl alcohol ether Glycerin monostearate

surfactant)

% 6.0 2.0 4.0 9.0 10.0 6.0 4.0 3.0 2.0 q.s.

Skin care cosmetics 347 Antioxidant: Perfume: Purified water:

q.s. q.s. 54.0

Manufacturing procedure Add the humectant to the purified water and heat to 70°C to make the water phase. After heating the oil component ingredients together to make a solution, add the surfactant, preservative, antioxidant and perfume and keep heating to 70°C. Add this to the water phase to carry out the preliminary emulsification. After making the emulsion particles uniform in size in a Homomixer, de-air, filter and cool. Typical formula 2. Emollient cream (O/W type; soap and non-ionic surfactant) %

Oil component:

Humectants: Surfactants: Alkali: Preservative: Antioxidant: Perfume: Purified water:

Cetyl alcohol Stearic acid Petrolatum Squalane Glycerol-tri-2 ethyl hexanoate Dipropylene glycol Glycerin Propylene glycol monostearate POE (20) cetyl alcohol ether Triethanol amine

5.0 3.0 5.0 10.0 7.0 5.0 5.0 3.0 3.0 1.0 q.s. q.s. q.s. 53.0

Manufacturing procedure Add the humectants and alkali to the purified water and heat to 70° C to make the water phase. After heating the oil component ingredients together to make a solution, add the surfactants, preservative, antioxidant and perfume and keep heating to 70°C. Add this to the water phase to carry out the preliminary emulsification. After making the emulsion particles uniform in size in a Homomixer, de-air, filter and cool. (3) Massage cream. Massage cream is the typical type of cold cream. For a long time, massage cream was made using the soap formed by the reaction of beeswax and borax as an emulsifier (see below) but the percentage of soap in the total amount of emulsifier has gradually been getting less. Recently, the number of massage creams which do not include any soap at all has been increasing because they feel light on use and spread well on the skin. Beeswax contains around 20% fatty acid (lignoceric acid - C23H47COOH, and cerotic acid - C25H51COOH, etc.). The soap is produced by the reaction between these fatty acids and borax. Na2B40v + 7H2O ^ 2NaOH + 4H3BO3 (borax) (boric acid)

(I)

348 New cosmetic science C25H51COOH + NaOH ^ C25H5iCOONa + H2O (cerotic acid, in beeswax) (sodium cerotate)

(II)

Combining (I) and (II): 2C25H51COOH + Na2B407 + 5H2O ^ 2C25H5iCOONa + 4H3BO3 The sodium cerotate acts as an emulsifier. Lignoceric acid reacts with borax in the same manner. Typical formula 1. Massage cream (0/W type; beeswax, borax and on-ionic Oil component:

Humectant: Surfactants: Alkali: Preservative: Antioxidant: Perfume: Purified water:

Solid paraffin Beeswax Petrolatum Liquid paraffin 1,3-butylene glycol Glycerin monostearate POE (20) sorbitan monolaurate Borax

surfactant) 5.0 10.0 15.0 41.0 4.0 2.0 2.0 0.2 q.s. q.s. q.s. 20.8

Manufacturing procedure Add the humectant and borax to the purified water and heat to 70° C to make the water phase. After heating the oil component ingredients together to make a solution, add the surfactants, preservative, antioxidant and perfume and keep heating to 70°C. Gradually add this to the water phase to carry out the preliminary emulsification. After making the emulsion particles uniform in size in a Homomixer, de-air, filter and cool. Typical formula 2. Massage cream (W/0 type; non-ionic Oil component:

Humectant: Surfactants: Preservative: Antioxidant: Perfume: Purified water:

urfactant)

Microcrystalline wax Solid paraffin Beeswax Petrolatum Reduced lanolin Squalane Hexadecyl adipate ester Propylene glycol Glycerin mono-oleate POE (20) sorbitan mono-oleate

% 9.0 2.0 3.0 5.0 5.0 34.0 10.0 5.0 3.5 1.0 q.s. q.s. q.s. 22.5

Skin care cosmetics 349 Manufacturing procedure After heating the oil component ingredients together to make a solution, add the surfactants, preservative, antioxidant and perfume and keep heating to 70° C to make the oil phase. Add the humectant to the purified water and heat to 70° C to make the water phase. As this cream is the W/0 type, gradually add the water phase to the oil phase to carry out the preliminary emulsification. After making the emulsion particles uniform in size in a Homomixer, de-air, filter and cool. (4) Cleansing cream. Originally cleansing creams were applied to the skin and only wiped off but with the need for creams which can be rinsed off in the toilet or bathroom to make them more convenient to use, the dual-use type which can be either wiped or rinsed off is now the main one on the market. In order to prevent any sticky feeling remaining after washing off, the proportion of solid and semi-solid oils in the oil phase has been reduced. Typical formula 1. Cleansing cream (O/W type; soap and non-ionic surfactant) Oil component

Humectant Surfactants Alkali Preservative: Antioxidant: Perfume: Purified water:

Stearic acid Cetyl alcohol Petrolatum Liquid paraffin Isopropyl myristate Propylene glycol Glycerin monostearate POE (20) sorbitan monostearate Potassium hydroxide

%

2.0 3.0 10.0 38.0 10.0 5.0 2.5 2.5 0.1 q.s. q.s. q.s. 26.9

Manufacturing procedure Add the humectant and alkali to the purified water and heat to 70° C to make the water phase. After heating the oil component ingredients together to make a solution, add the surfactants, preservative, antioxidant and perfume and keep heating to 70° C. Gradually add this to the water phase to carry out the preliminary emulsification. After making the emulsion particles uniform in size in a Homomixer, de-air, filter and cool. (5) W/0 type emollient cream. Formerly, with a W/0 emulsion, a cream with good stability could only be obtained by raising the viscosity of the external phase (oil phase) which made it feel oily and sticky on use, so, as an emollient cream, this type of cream was not very popular. However, with the development of such techniques as the amino acid gel emulsification technique'^^-^^) and organically modified clay mineral gel emulsification technique^^-^^), which cover a wide range of water phase types (water and humectant) and produce high stability, even if the amounts of solid and semi-solid oils in the water phase are greatly reduced, it is now possible to manufacture emollient creams catering to a wide range of needs.

350 New cosmetic science

Typical formula 1. Emollient cream (W/0 type; amino acid gel emulsion) 70

Oil component: Surfactant: Preservative: Perfume: Water phase (1): Water phase (2): Purified water:

Liquid paraffin Microcrystalline wax Petrolatum Diglycerol dioleate L-Sodium glutamate L-Serine Purified water Propylene glycol

30.0 2.0 5.0 5.0 q.s. q.s. 1.6 0.4 13.0 3.0 40.0

Manufacturing procedure Make a solution of the w^ater phase (1) ingredients, heating to 50° C and while stirring, gradually add this to the surfactant, which has also been heated to 50° C to make a W/D (surfactant phase) emulsion compound (amino acid gel). Next, make a solution of the oil component ingredients at 70° C and evenly disperse the W/D (surfactant phase) emulsion compound through it. Then, heat the water phase (2) ingredients to 70° C and add this to the dispersion, thoroughly stirring while doing this. Make the emulsion particle size uniform in a Homomixer, de-air, filter and cool to 30°C. Typical formula 2. Emollient cream (W/O type; organically modified clay mineral oily gel emulsion) % Oil component: Squalane 20.0 Cetyl iso-octanoate 8.5 Microcrystalline wax 1.0 Clay mineral: Organically modified clay mineral 1.3 Surfactant: POE glycerol tri-isostearate 0.2 Humectant: Glycerin 10.0 Preservative: q.s. Perfume: q.s. Purified water: 59.0 Manufacturing procedure After heating the oil component ingredients together to make a solution, add the clay mineral, surfactant, preservative, antioxidant and perfume and heat to 70° C to make a uniform solution which is the oily gel. Add the humectant to the purified water and heat to 70° C to make the water phase. Gradually add the water phase to the oil gel, stirring thoroughly. After making the emulsion particles uniform in size in a Homomixer, de-air, filter and cool to 30°C. (6) Anhydrous oily cleansing cream. This type of cream is also known as liquefying cream and it consists only of oils which have not been emulsified. As it is easy to make, this cleansing cream has been made for many years.

Skin care cosmetics

Typical formula 1. Anhydrous oily cleansing cream Oil component:

Hardening agent: Perfume:

Ceresin Microcrystalline wax Petrolatum Liquid paraffin Low molecular weight polyethylene

351

% 8.0 5.0 35.0 50.0 2.0 q.s.

Manufacturing procedure Leaving out the perfume, mix all the ingredients together and make a solution at about 90° C; then cool to around 60° C and add the perfume. It is necessary to take care with this formula with regard to the solubility of the low molecular weight polyethylene because the stability of the final product can vary greatly depending on the stirring conditions between 90°C and 70°C when cooling, as well as after the cream has solidified.

1.6. Gels 1.6J. Purposes and functions of gels Gels, which include gels and jellies, are a type of base which produce a uniform external appearance, range from transparent to semitransparent and give a moist feeling. Aqueous gels have been used in under makeup creams for summer use because of their special feature of giving a moist and light feeling. Recently, however, with the development of various new production technologies, aqueous and oily gels having other than water-supplying and moisturizing functions, i.e. gels for stimulating the circulation, cleansing and makeup removal, have come on to the market and are enjoying great popularity. As aqueous gels contain a lot of moisture, they are used as a base material with water supplying, moisturizing and cooling effects or as the base of a cleansers for light makeup. As they impart a moist, light and cool feeling, they are employed in cosmetics for summer use and those for oily skin. Oily gels are used to supply oil to the skin and, applied together with lotion, are used as a winter product or for dry skin because of their moisturizing properties. Owing to their great affinity for thick makeup, they are made into cleansers for removing makeup by combining them with suitable quantities of various surfactants. Various gels are listed in Table LIO according to their purpose and functions. L6.2, Main ingredients of gels Water soluble polymer substances with gelling ability are much used in aqueous gels. Examples of this are carboxyvinyl polymer and methyl cellulose. The gel product consists of the gel base and the humectants, surfactants, preservatives, pharmaceutical agents, coloring agents and perfumes that have been added. As gel products are usually transparent, care is required to ensure that the additives are uniformly dissolved and dispersed in them.

352 New cosmetic science Table 1.10. Purposes and functions of different gels Purpose/ function

Gel type

Features

Water No oil Giving a moist, cool and light feeling, Aqueous gel supplying they are suitable for summer products (polymer thickened type) Moisturizing Small amount of oil and oily skin. Produce little occlusion. Moisture retention Supply oil

Oily gel (emulsion or liquid crystal type)

Its moistness and low friction provided by polymers make it smooth to apply and easy to massage into the skin. The type with a lot of humectant and little water gives a warm feeling.

Stimulating circulation Aqueous gel (massage in)

Aqueous gel (polymer thickened type)

Cleanser Makeup removal

Being oily they have the feeling of an oily cream. Good for moisture retention and augmenting skin oil in winter and dry skin.

Can be rinsed off with water or wiped off ; non-oily but cleansing effect drops off for heavy makeup. Low cleansing Small amount of oil power. No oil

Oily gel (emulsion or liquid crystal type)

High affinity for makeup ; becomes lighter during use due to 0 / W phase inversion. Can be rinsed off with water more easily after this. Very suitable for removing heavy makeup and has high cleansing power.

Oil gel

Has high affinity for makeup. As it cannot be rinsed off, it is wiped off. Leaves an oil film which must be cleaned off using a cleansing foam. High cleansing power

There are oil-containing emulsion-type aqueous gels which are transparent, as well as semi-transparent or opaque gels made by adding a small amount of oil and a surfactant to an aqueous gel. Oily gels make use of the gelling ability and liquid crystal structure of surfactants. Among them are emulsion types which have been made transparent by adjusting the refraction indices of the internal and external phases. For oil gels, it is necessary to have a combination of oils with good compatibility, select appropriate oil phase gelling agents and use materials in combinations which maintain the stability of the gel. So, when making a formula for a gel, it should be designed based on a very broad understanding of the ingredients considering such things as stability, safety, preservation and ease of use, in accordance with the features it is supposed to have.

Skin care cosmetics 353 1.6.3.

General manufacturing

methods for

gels

Gels generally have high viscosities so it is necessary to select the equipment for making them in view of this. For example, mixing equipment should be capable of uniform mixing; there should be equipment for removing air bubbles and equipment suited to the transportation, filtering and cooling of high viscosity substances. As transparency is important for gels, attention should be paid to the dissolution and uniformity of the raw materials. 1.6.4. Types of gel (1) Gels for cleansing and removing makeup. Because their moist feeling is liked so much, gel sales are growing rapidly. Oily gels for the removal of makeup can be rinsed off easily after rubbing thoroughly into the makeup and they give a light feeling after use. Typical formula 1. Oily gel (emulsion type) Oil component: Humectant: Surfactant:

Liquid paraffin Glycerol tri-2-ethylhexanoate Sorbitol PEG 400 Acylmethyl taurate POE octyl dodecyl alcohol ether

Perfume: Purified water:

% 12.0 50.0 10.0 5.0 5.0 10.0 q.s. 8.0

Manufacturing procedure Add the humectant and acylmethyl taurate to the purified water and heat to 70°C. Add the POE octyl dodecyl alcohol ether and perfume to the oil component and heat to 70°C. Add this gradually to the water phase. After making into an emulsion of uniform particle size in a Homomixer, de-air, filter and cool (as the refractive indices of the water and oil phases are close together, this makes a gel which is transparent to semi-transparent) (2) Water supplying and moisturizing gel Typical formula. Moisturizing Humectant: Water-soluble polymer: Surfactant: Alkali: Preservative: Anti-fading agent: Coloring agent:

gel Dipropylene glycol PEG 1500 Carboxyvinyl polymer Methyl cellulose POE (15) oleyl alcohol ether Calcium hydroxide

% 7.0 8.0 0.4 0.2 1.0 0.1 q.s. q.s. q.s.

354 New cosmetic science Chelating agent: Perfume: Purified water:

q.s. q.s. 83.3

Manufacturing procedure After dissolving the carboxyvinyl polymer and methyl cellulose in the distilled water, add the PEG 1500, anti-fading agent, coloring agent and chelating agent. Add the surfactant to the dipropylene glycol and heat to 50-55°C to dissolve; then add the preservative and perfume. Add this gradually to the water phase while mixing. Finally, add an aqueous solution of the alkali and mix thoroughly to achieve neutrality.

1.7. Essences (beauty lotions)56^o) 1,7J,

Purposes and functions of essences

Recently, the improvement of skin roughness has been studied not only by observation of the skin surface but by physiological methods as well. Instruments have been used to measure changes in TWL (transepidermal water loss) and recovery in skin conductance, and research has been carried out on the recovery of incomplete keratinization and epidermal amino acid metabolism and other physiological changes. At about the same time as this has been happening, cosmetic products known as essences have started to frequently appear on to the market. Essences are not a new type of product. Some of the reasons that there is such a big market for them are as follows: changing user lifestyles, for example, people want to simplify their daily cosmetic routine to save time; the image that "concentrated" means that the product has a better effect; they are convenient to use because of improved container design; the development of highly functional moisture retaining agents (emollients and humectants) and pharmaceutical agents (whitening agents, cell rejuvenating agents, ultraviolet screening agents) based on skin physiology; advances made in production techniques in pace with such development and proof of their usefulness. Essences make up for what is lacking in conventional skin care cosmetic products in terms of effects, feeling when used, beauty systems, etc.. In other words, they are positioned as value-added cosmetic products which have at least one prominent effect from among humectant, ultraviolet screening, whitening, anti-oxidation, anti-inflammatory and rejuvenation, or have multiple functions. Different types of essence preparations are listed in Table 1.11. There are a great many of the transparent/semi-transparent viscous liquid type on the market. 1.7.2. Main ingredients of essences As mentioned above, essences come in many different types and forms. However, there are many which are common to lotions, emulsions, creams and oils so only the main ingredients of the transparent viscous liquid type have been listed in Table 1.12. Because essences are used in small amounts and must fulfill a lot of requirements such as those for body and affinity as well as a soft, moist and supple feeling after use, the se-

Skin care cosmetics 355 Table 1.11. Different types of essence and their features Type

Features

Technologies

Transparent/ Semitransparent lotion type

In general contain more humectant than lotions. The Solubilization, micro- texture may be adjusted through the selection of the emulsion, liposome, disc- humectant and water-soluble polymer and varying their combinations. This is the most general form of essence like capsule preparation.

Emulsion type

0 / W type, W / 0 type, W / O / W type

As this type can contain a large amount of emollient (oil component) it is suitable for preparations containing large amounts of ultraviolet absorber and other oily ingredients. The W / 0 type is suitable for preparations requiring a water repellence. This type has been used as a cosmetic oil since long ago. The texture is adjusted by combining solid or semi-solid oils and animal fats or plant oils such as olive oil, jojoba oil, mink oil or squalane in different proportions. As the texture of this type is not as good as that of other preparations it is disappearing from the market.

Oil type

Two-agent mixtogether type

In order to prevent instability in the pharmaceutical agent In addition to the above, and preparation or to effect a visual change, two agents spray-dry, freeze-dry and are mixed together on use. There are liquid-liquid and m i c r o c a p s u l e technolliquid-powder combinations. Powders are prepared so ogies are also used. that they dissolve easily.

Others

Lotion with powder type Much alcohol type

Essences for the T zone which secretes a lot of sebum. Including sebum absorbing powder increases lasting power of makeup. Essences having a germicidal effect for acne preparations.

lection and combination of water soluble polymers and humectants must be done skillfully. 1.7.3. General manufacturing methods for essences This is not described here as it will be discussed in detail in the sections on lotion, emulsions and creams. 1.7.4. Types of essence Typical formula 1. Transparent moisturizing essence Humectants:

Alcohol: Surfactant:

Sorbitol 1,3-butylene glycol PEG 1500 Hyaluronic acid Ethanol POE oleyl alcohol ether

% 8.0 5.0 7.0 0.1 7.0 1.0

356 New cosmetic science Table 1.12. Main ingredients of transparent viscous essences Ingredient

Typical raw materials

Humectant

Polyethylene glycol (300, 400, 1500, 4000), glycerin, dipropylene glycol, 1,3 butylene glycol, sorbitol, multitol, hyaluronic acid, chondoroitin sulfate, collagen, elastin, pyrrolidone carboxylate, amino acids

Alcohol

Ethanol, isopropyl alcohol

Water soluble polymer (thickening agent)

Carboxyvinyl polymer, sodium polyacrylate, cellulose derivatives, sodium alginate, quince seed gum, pectin, xanthan gum, gum arable, Irish moss, pullulan, tragacanth gum

Surfactant

POE oleyl alcohol ether, POE sorbitan monolaurate, POE/POP block copolymers, POE fatty acid esters, POE hardened castor oil ester

Emolient

Plant oils (jojoba oil, olive oil, etc.), oleyl alcohol, ester oils, squalane, lanolin derivatives Whitening Rejuvenating

Pharmaceuti Anti-oxidation cal agent Ultraviolet screening Germicidal Anti-inflammatory Others

Emollient: Perfume: Preservative: Anti-fading agent: Buffer: Purified water:

Vitamin C and its derivatives, placenta extracts, arbutin, kojic acid Pantothenyl ethyl ether, hormones, DNA, vitamins, animal and fungi extracts Vitamin E and its derivatives, amino acids 2-hydroxy-4-metoxy-benzophenone, Ti02, octyl methoxy cinnamate, para-amino benzoate, etc. TCC, Photosensitizer, etc. Allantoin, glycyrrhizinic acid salts, glycyrrhetinic acid esters, etc. Perfumes, coloring agents, preservatives, anti-fading buffers (refer to section on lotions)

Olive oil

agents,

0.2 q.s. q.s. q.s. q.s. 71.7

Manufacturing procedure Dissolve the humectant, anti-fading agent and buffer in the purified water. Dissolve the surfactant, emollient, perfume and preservative in the ethanol and then add this to the water phase and filter. Typical formula 2. Semitransparent whitening essence (microemulsion viscous liquid) Vc

Humectant: Alcohol: Water soluble polymers:

Dipropylene glycol PEG 400 Ethanol Carboxyvinyl polymer Sodium alginate

5.0 5.0 10.0 0.3 0.3

Skin care cosmetics 357 AlkaU: Surfactant: Emollient: Pharmaceutical agents:

Potassium hydroxide POE sorbitan monostearate Sorbitan mono-oleate Oleyl alcohol Placenta extract Vitamin E acetate

Perfume: Preservative: Anti-fading agent: Purified water:

0.15 1.0 0.5 0.5 0.2 0.2 q.s. q.s. q.s. 76.85

Manufacturing procedure First dissolve the water soluble polymer in the purified water, and then the humectant and the anti-fading agent. Dissolve the surfactant, emollient, vitamin E acetate, perfume and preservative in the ethanol and add this to the water phase to produce a microemulsion. Finally, dissolve the potassium hydroxide in some of the distilled water, add this to the microemulsion, mix, de-air and filter. Typical formula 3. Ultraviolet screening essence (OAV emulsion) Vc

Oil component:

Humectant: Surfactants: Alkali: Ultraviolet absorbents: Preservative: Perfume: Purified water:

Stearic acid Cetanol Lanolin derivative Liquid paraffin 2-ethyl hexyl stearate 1,3-butylene glycol POE cetyl alcohol ether Glycerin monostearate Triethanol amine 2-hydroxy-4-metoxy benzophenone Dibenzoylmethane derivative

3.0 1.0 3.0 5.0 3.0 6.0 2.0 2.0 1.0 4.0 4.0 q.s. q.s. 66.0

Manufacturing procedure Dissolve the humectant and triethanol amine in the purified water and heat to 70° C and keep at this temperature. After dissolving the oil component at 70-80°C, dissolve the surfactant, ultraviolet absorbent, preservative and perfume, and adjust the temperature to 70°C. Add the oil phase to the water phase while stirring, in order to make an emulsion. Using a Homomixer, make the emulsion uniform; then de-air and cool.

1.8. Packs and masks 1.8.1. Purposes and functions of packs and masks Packs are a cosmetic product which have been in use since long ago. Packs are not just

358 New cosmetic science Table 1.13. Different types of pack and their features Type

Peel-off type

Wipe-off and rinse-off types

Peel off when hard type

Adhesive fabric type

Product form

Features

Jelly

Transparent or semitransparent jelly forming a transparent film on the skin after drying. After the film is peeled off, the skin feels moist, soft and very clean.

Paste

Opaque paste. As relatively large amounts of powder, oil and humectant can be incorporated in the paste, the skin feels soft and moist when the film formed by the paste on drying is peeled off.

Powder

The powder is added to water to make a uniform mixture which is applied to the skin. As the latent heat of vaporization of the water comes from the skin, it is cooled giving a light and slightly stretched feeling, which makes this type suitable for summer.

Cream

An ordinary 0 / W emulsion-type cream which has been given a low hardness to make it easier to apply. It contains a lot of humectant to give a good moist feeling after use.

Mud pack

A powder including clay minerals is mixed with the water phase formed from water, ethanol and humectant. As this is difficult to wipe off when dry, this type is mainly rinsed off.

Jelly

Transparent or semitransparent jelly. Even when the jelly is achieved through the use of a water soluble polymers, not much film-forming agent is used, so it is still wiped or rinsed off.

Aerosol (foam type)

In vaporization, the gas used takes heat away from the skin too rapidly making it smart and giving it a prickly feeling-the drawback of this type.

Powder

The main ingredient is plaster of Paris. Heat of hydration produced when water is added causes it to harden. CaS04 • I/2H2O + 3/2H2O >CaS04 • 2H20 + 8.2kcal

Non-woven adhe- Texture depends on nature of gel used. Being a new type of sive fabric with gel pack it is attracting attention. It is easy to use and has a very good effect when used together with other skin care cosmetics. type Non-woven fabric impregnated type

Non-woven fabric impregnated with lotions or essences. Gives a cool, comfortable feeling. Easy to use.

for the face; they are used all over the body - for example, on the neck, shoulders, arms and legs. Table 1.13 shows the variety of different pack preparations. Some of the functions of packs are as follows: (1) The skin's horny layer is maintained in a moist condition as a result of the moisture from the pack, humectant and emollient, and the moisture coming up from under the skin is kept in due to the pack's occlusive effect, hence making the skin more supple. (2) As packs have an adsorbent action and remove skin surface dirt when peeled off after drying, they are an excellent cleanser for the skin.

Skin care cosmetics 359

(3)

The drying of the film on the skin and the powder produces just the right amount of tension in the skin. After drying, the skin temperature rises and it invigorates the circulation. With the exception of the adhesive fabric type, all types of pack are applied to the skin in a suitable thickness and, after leaving for a set time, are peeled or rinsed off. As the peel-off type is very effective in removing old horny layer, it is good to use it once or twice a week. The problem with packs is that they have to be left on for a long time so they are not used very frequently in the home as people have such busy lives but they are a very important product for beauty salons because customers are very satisfied with the effect. Methods of shortening the drying time are now being developed. 1.8.2. Main ingredients of packs and masks As the materials used vary according to the type of pack, only those for the jelly and paste peel-off packs, the main types of pack in skin care cosmetics, are given in Table 1.14. 1.8.3. General manufacturing methods for packs and masks As the method for making packs and masks varies depending on the type, only those for the paste form peel-off type and the rinse-off mud type are given below. Table 1.14. Main ingredients of peel-off packs (jelly-type, paste-type) Typical ingredient

Ingredient

Amount 40-80%

Purified water

Ion exchanged water

Alcohol

Ethanol

Humectant

Polyethylene glycol (300, 400, 1500, 4000), glycerin, propylene glycol, dipropylene glycol, 1,3-butylene glycol, sorbitol and other saccharides, mucopolysaccharides, PCA-Na, etc.

2—15

Film forming agent and thickener

Polyvinyl alcohol, polyvinyl pyrrolidone, polyacetic acid vinyl emulsion, carboxymethyl cellulose, pectin, gelatin, xanthan gum

10—30

Oil component (emollient)

Olive oil, macadamia nut oil, jojoba oil, liquid paraffin, squalane, ester oils, etc.

—15

Powder

-15%

Kaolin, talc, titanium dioxide, zinc oxide, spherical cellulose, etc.

-20

Coloring agent

Permitted colorants, inorganic pigments.

q. s.

Pharmaceutical agent

Whitening agent : vitamin C and its derivatives, placentaextract Rejuvenator : pantothenyl ethyl ether, vitamins, animal and plantextracts Anti-inflammatory : Allantoin, glycyrrhizinic acid salts Germicide : Photosensitiger, TCC

q. s.

Preservative

Paraben

q. s.

Surfactant

POE oleyl alcohol ether, POE sorbitan monolaurate

Buffer

Citric acid, lactic acid, amino acids, sodium citrate, sodium lactate.

-

2% q. s.

360

New cosmetic

Water phase

Alcohol phase

science

Purified water Powder Humectant — Film agent —

Mixing —T-^ Heating — Dispersion 1 Dissolution 1 70-80°C

r Dispersion 1 [DissolutionJ

r

Mixing 1 [DissolutionJ [Deairing]

Ethanol Perfume Preservative Surfactant "

I 1

Dissolution-

[Filtering] [Cooling] [Storage] [Filling]

Fig. 1.10. Manufacturing process for paste-form peel-off pack.

The points requiring attention in the manufacture of paste form peel-off packs are the dispersion and dissolution of the film agent and the dispersion of the powders. It takes time to dissolve the film agent and it must be checked that it has dissolved uniformly and that there is none left undissolved. The powder must be well dispersed to prevent precipitates forming due to secondary coagulation (Fig. 1.10). With the exception of the heating required to dissolve the preservative and the surfactant, the manufacturing of the rinse-off mud pack is basically done at room temperature. The points requiring greatest attention are the dispersion of the clay minerals and the uniform mixing of powders into the water phase. If this is not done sufficiently well, the mud pack will not be smooth, there will be lumps in it and the water phase could separate with time (Fig. 1.11). 1.8.4. Types of pack and mask Typical formula 1. Jelly-form peel-off type 15.0 5.0

Polyvinyl alcohol Carboxymethyl cellulose

Film agent: Thickening agent:

{

Purified water -TClay mineral —^ Humectant

-*• Mixing — Dispersion room temp

• [Dissolution]-

r Mixing 1 |_DispersionJ [Deaiming]

f Ethanol . . . [Dissolution] Preservative Alcohol phase Perfume — Surfactant"

J

Powders —

[Pulverization] -

I

[Filtering] [Storage]

I

[Filling]

Fig. 1.11. Manufacturing process for rinse-off mud pack.

Skin care cosmetics 361 Humectant: Alcohol: Perfume: Preservative: Buffer: Surfactant: Purified water:

1,3-butylene glycol Ethanol

POE oleyl alcohol ether

5.0 12.0 q.s. q.s. q.s. 0.5 62.5

Manufacturing procedure After adding the buffer and humectant to the purified water, heat to 70-80° C. Add the thickening agent, film agent and mix to dissolve. After dissolving the perfume, preservative and surfactant in the alcohol, add this to the water phase and dissolve. Then deair, filter and cool. Typical formula 2. Paste-form peel-off type Film agents: Humectants: Oil component: Surfactant: Powders: Alcohol: Perfume: Preservative: Purified water:

Poly acetic acid vinyl emulsion Polyvinyl alcohol Sorbitol PEG 400 Jojoba oil Squalane POE sorbitan monostearate Titanium dioxide Talc Ethanol

% 15.0 10.0 5.0 5.0 2.0 2.0 1.0 5.0 10.0 8.0 q.s. q.s. 37.0

Manufacturing procedure To the purified water, add the powders and after they are sufficiently dispersed, add the humectants. After heating to 70-80°C, add the film agent and dissolve. To the ethanol add the perfume, preservative, surfactant and oil component. Mix this together with the water phase. De-air, filter and cool. Typical formula 3. Powder-form peel-off type When this type is dissolved in water, a calcium alginate gel is produced which forms the film. % Powders: Kaolin 30.0 Talc 20.0 Gelling agent: Sodium alginate 10.0 Gelling reactant: Calcium sulfate 35.0 35.0 Gelling regulator: Sodium carbonate 5.0 Coloring agent: q.s. Perfume: q.s.

362

New cosmetic science

Manufacturing procedure To the powders add the gelling agent, gelling reactant, gelling regulator, coloring agent and perfume in that order, mix and fill. Typical formula 4. Mud-form wash-off type After they have dried a bit, some products of this type and the cream-form wash-off type are rubbed in with the palms and then washed off (gommage type). % Humectants: Dipropylene glycol 5.0 PEG 400 8.0 Glycerin 10.0 Clay mineral: Montmorillonite 2.0 Alcohol: Ethanol 8.0 Powders: Titanium dioxide 5.0 Kaolin 10.0 Talc 5.0 Perfume: q.s. Preservative: q.s. Surfactant: q.s. Purified water: 47.0 Manufacturing procedure To the purified water add the clay mineral and the humectant ensuring sufficient wetting and dispersion. Dissolve the preservative, perfume and surfactant in the ethanol and add this to the water phase. Next, add the powders, ensuring that there is sufficient dispersion, de-air and filter. Typical formula 5. Jelly-form wipe-off or wash-off type Humectants: Thickening agents: Alkali: Surfactant: Alcohol: Perfume: Preservative: Purified water:

PEG 1500 Dipropylene glycol Sorbitol Carboxyvinyl polymer Xanthan gum Potassium hydroxide POE lauryl alcohol ether Ethanol

% 5.0 5.0 5.0 1.0 0.5 0.5 1.0 5.0 q.s. q.s. 77.0

Manufacturing procedure To the purified water add the thickening agent and mix to dissolve. Dissolve the perfume, preservative and surfactant in the ethanol and solubilize this in the water phase. Finally, dissolve the potassium hydroxide in some of the purified water and add this to the solution to neutralize it, de-air and filter.

Skin care cosmetics 363

1.9. Shaving cosmetics 1.9.1. Purposes and functions of shaving cosmetics Skin care cosmetics such as cleansing foams, lotions, milky lotions, skin creams, essences and packs are also provided for men. As men have more sebum on their skin than women, male cosmetics have a lower oil content and as they like a light feeling, many cleansing foams for the face contain a scrub agent. As well a producing a lot of sebum, many men have dry rough skin in winter. The dryness is prevented with milky lotions and essences which give a non-oily feeling when used. However, men use shaving cosmetics much more than such skin care products and as the formulations of these skin care cosmetics are similar to those for women, only shaving cosmetics, i.e. those for use before and after shaving, will be discussed here. Shaving cosmetics comprise shaving soap, shaving cream, pre-shaving lotion and after-shaving lotion. As well as making shaving easier by making the beard swell and softening it when applied before shaving, shaving soap and shaving cream prevent skin roughness due to shaving and leave a nice feeling when used. Almost all products currently on the market are the cream type. As the name suggests, pre-shaving lotion is also applied before shaving, but it is specially for electric shavers. Pre-shaving lotion helps electric shavers to slide better over the face and contain astringents and alcohol to stretch the skin in order to make the hairs stand up more rigidly, which makes shaving easier with an electric shaver. After-shaving lotion is a skin care cosmetic product applied after shaving which has a sterilizing action and gives a moist feeling to the skin. 1.9.2. Types of shaving cosmetics (1) Shaving soap. Among shaving soaps, the liquid, powder and granule types are mainly for use at barber shops and other commercial establishments. The solid type is for general use. It is necessary to prevent the powder and granule types from becoming solid through the absorption of moisture. The biggest difference between the solid type and ordinary toilet soap, which it resembles, is that lather is stressed in its formulation rather than cleansing power. So, in addition to having an oil/fat composition producing a uniform, viscous, thick, longlasting, rich lather, a lot of glycerin and other superfatting agents are often included in the formulation. (2) Shaving cream. Lathering cream and aerosol shaving cream are examples of the types of shaving cream available. Lathering cream contains 40-50% fatty acid soap. Emulsifying the soap and making the cream alkaline swells the hairs and makes them soft which lightens the task of shaving. Shaving creams are used as follows: the beard is wet with cold or warm water and then the cream is applied and worked into a lather with a wet brush. The beard is then shaved with a razor and afterwards rinsed with water. The main fatty acids used are stearic acid and coconut fatty acid. In consideration of lathering, the lasting quality of the lather and stimulating the skin, the proportions are

364 New cosmetic science

normally made 75% stearic acid and 25% coconut oil. And, in the saponification it is usual to use a mixed alkali, comprising potassium and sodium hydroxides, which maintains the cream at a suitable hardness and prevents any changes in hardness at high or low temperatures. Triethanol amine has a strong tendency to make the soap yellow so care must be taken in this respect. Further, the addition of glycerin or other humectant is very effective in preventing drying during shaving and, including petrolatum in the formula or using superfats is very effective in giving the skin a moist feeling. The total fatty acid content of a cream is 35-50% and its pH around 10. Free fatty acid and glycerin lower lathering ability but as glycerin is used as a humectant, as described above, it is necessary to carefully consider the qualities of both together when deciding on their quantities. Typical formula 1. Lathering cream Oil component:

Humectant: Alkali: Antioxidant: Perfume: Purified water:

Stearic acid Palmitic acid Coconut oil Palm oil Glycerin Potassium hydroxide Sodium hydroxide

% 25.0 5.0 10.0 5.0 10.0 7.0 1.5 q.s. q.s. 36.5

Manufacturing procedure Dissolve the potassium hydroxide and sodium hydroxide in the purified water, add the glycerin and heat to 80°C (water phase). Leaving out the perfume mix all the other ingredients together, heat to dissolve and keep at 80°C (oil phase). Gradually add the water phase to the oil phase and after adding all of it, allow the saponification reaction to fully take place. Cool to 50° C, add the perfume, mix till uniform and cool to 30°C. In addition to lathering cream, there is also the aerosol-type shaving foam, which is sold widely. This is considered to be because of the dynamic feeling of the foam and its convenience of use. Some of its other excellent features are: it softens the beard, retains moisture during shaving and it allows the razor to glide easily over the face. Owing to the recent popularity of the 2-blade razor, the foam has been made softer so that it does not clog up the blades. Aerosol shaving foams consist of a propellant and a concentrate. In order to maintain the foam for as long as possible, and make shaving easier, the concentrate is an emulsion made from soap and non-ionic surfactant. The propellant sprays the stock solution out of the container to form the foam. The softness of the foam is controlled by the type of emulsifier used. In order to prevent the destruction of the ozone layer, such alternatives to chloroflurocarbons as liquefied gaseous hydrocarbons and dimethylether are now being used for the propellant.

Skin care cosmetics 365

Typical formula 2. Shaving foam Concentrate formula Oil component: Surfactant: Humectant: Alkali: Perfume: Purified water: Filling formula Concentrate: Propellant (LPG):

Stearic acid Coconut oil fatty acid Glyceryl monostearate Glycerin Triethanol amine

% 4.5 1.5 5.0 10.0 4.0 q.s. 75.0 96.0 4.0

Manufacturing procedure To make the concentrate, add the glycerin and the triethanol amine to the purified water and heat to 70°C (water phase). Heat the other ingredients to dissolve and keep at 70°C (oil phase). Add the oil phase to the water phase and allow the reaction and emulsification to take place. Then cool to 30°C. Fill cans with the prescribed amount of the concentrate and after attaching the valve add the prescribed amount of propellant. Recently, the new-type after-foaming aerosol shaving foam has come on to the market. In this type an emulsion is formed by introducing a gas with a high boiling point (30-40° C) into a gel base at a low temperature and this is sealed in a double aerosol container. The inner container is filled with concentrate containing isopentane (boiling point 28°C) and the outer container with LPG. After the concentrate has been expelled from the aerosol container, it is heated by the skin which vaporizes the isopentane and makes the foam. The foam type is thus more convenient than the lathering cream type because there is no need to apply water and use a brush to work up a lather. Typical formula 3. After-foaming gel cream Oil component: Humectant: Surfactant: Alkali: Purified water: Foaming agent:

Palmitic acid Glycerin POE-POP block copolymer Triethanol amine Isopentane

% 10.0 15.0 5.0 6.0 59.0 5.0

Manufacturing procedure Add the alkali, and humectant to the purified water and heat to 70°C (water phase). Melt the palmitic acid at 70° C and add to the water phase. Then add the surfactant. After introducing this base solution into a container add the isopentane. Shake the container so that the isopentane forms a uniform emulsion. (3) Preshaving lotion. As the use of electric shavers has increased, the lotion-type of preshaving lotion is now widely used. It is applied before shaving to make it easier. There

366 New cosmetic science are two types. One contains zinc phenolsulfonate, tannic acid or other astringent to draw the skin together so that the hairs stand up and the other globular powders to make electric shavers slide more easily over the face. Typical formula 1. Preshaving

lotion 70

Astringent: Alcohol: Oil component:

Zinc phenolsulfonate Ethanol Isopropyl myristate Isopropyl palmitate

Perfume: Typical formula 2. Preshaving lotion containing Alcohol: Powder: Oil component: Humectant: Pharmaceutical agent: Perfume:

1.0 84.0 7.0 8.0 q.s.

powder

Ethanol Spherical powder Glyceryl tri-2-ethylhexanoate 1,3-butylene glycol Vitamin E acetate

% 94.0 4.0 1.0 1.0 q.s. q.s.

To best lubricate the passage of the electric shaver over the face, the powder should be globular in form and have a low specific gravity. (4) After-shaving lotion. After shaving lotion is a type of astringent lotion used after shaving to help heal cuts due to shaving, prevent drying of the skin and give a refreshing, cool feeling. The main types are those containing alcohol designed mainly to provide a cool, refreshing feeling and germicidal effect; those providing a cool, refreshing feeling and an anti-inflammatory effect, by cutting down on the alcohol and adding menthol and camphor; and those keeping the secretion of sebum under control through the use of powders. Each type has the ability to prevent infection in shaving cuts, draw the skin together and prevent it from drying out. Typical formula 1. High alcohol formula Alcohol: Humectant: Surfactant: Pharmaceutical agent: Plant extract: Perfume: Germicidal agent: Purified water: Ultraviolet absorbent:

type

Ethanol Dipropylene glycol POE hardened castor oil ester AUantoin Aloe extract

% 55.0 2.0 1.0 0.1 q.s. q.s. q.s. 41.9 q.s.

Manufacturing procedure Dissolve the dipropylene glycol and the allantoin in the purified water (water phase). Dissolve the other ingredients in the ethanol (alcohol phase). Solubilize the water phase in the alcohol phase and then filter.

Skin care cosmetics 361

1.10. Other cosmetics (1) Powder products. Powder, granule and capsule type products containing vitamin C or vitamin C derivatives, which are made into aqueous solutions will now be described. Such ingredients have poor stability in aqueous solution. Vitamin C and its derivatives have a reducing action and inhibit tyrosinase activity. Powder products containing them come under the category of whitening cosmetics. When using them, some powder is placed on the palm of the hand and about 10 times as much water is added to dissolve the powder. This aqueous solution is applied to the face. If the formula contains ascorbic acid dipalmitate, which is hydrophobic, an excipient and a dissolution aid may be added and the product made into granules in order to make it easier to dissolve in water. Typical formula 1. Powder type (whitening Humectants: Powder: Pharmaceutical agents:

powder)

Cane sugar PEG 6000 Silica Vitamin C Vitamin C dipalmitate

Coloring agent:

% 60.0 20.0 5.0 5.0 10.0 q.s.

Manufacturing procedure Mix the humectant, powder, pharmaceutical agents and coloring agent together and grind. Fill containers after dividing into smaller amounts. (2) Cleansing oil. This product is used as a face cleanser for removing heavy makeup. The cleanser is mixed in well with the makeup and removed. There are two types, one which is wiped off and the other is rinsed off. The latter is now the main type. The main ingredients are an oil which goes well together with the makeup, and a surfactant to aid rinsing off. With this type of product, attention should be paid to the selection and combination of the surfactants in order to ensure the formation of the O/W emulsion when rinsing off. Typical formula. Cleansing oil (for rinsing off) Oil component:

Surfactant: Perfume:

Liquid paraffin 2-ethyl hexyl stearate Silicone oil POE oleyl alcohol ether

% 50.0 20.0 20.0 10.0 q.s.

Manufacturing procedure Mix the oil component, surfactant and perfume together to dissolve. Then filter and prepare as product.

368 New cosmetic science

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56.

Tanaka, M.: Fragrance J., 9, 13 (1994). Kitamura, K.: The 18th. IFSCC, Preprints, 1994. Ozawa, T. et al:. Skin Res., 27 (2), 276 (1985). Nilsson, G. E.: Med. Biol. Eng. Comput., 15, 209 (1977). Kligman, A. M., Takase, Y.: Cutaneous Aging, University of Tokyo Press, 1988. A. Seakall: Get Pat, 1025, 101 (1958). Wolfersberger, M. G., Tabachnick, J., Finkelstein, B. S., Levin, M.: J. Invest. Dermatol., 60, 278 (1973). Koyama, J., Horii, I., Kawasaki, K., Nakayama, Y., Morikawa, Y., Mitsui, T.: J. Soc. Cosmet. Chem., 35, 185 (1984). Ozawa, T. et al.: Fragrance J., 11 (4), 297-307 (1987). Jacobi, O. K.: Proc. Sci. Sect., TGA, 31, 22 (1959). Horii, I.: J. Br. Dermatol., 121, 587 (1989). Denda, M.: Arch. Dermatol. Res., 284, 363 (1992). Nakayama, Y. et al.: J. Soc. Cosmet. Chem. Jpn., 20 (2), 111 (1986). Middleton, J. D., Roberts, M. E.: J. Soc. Cosmet. Chem., 29, 201 (1987). Takahashi, M. et al.: J. Soc. Cosmet. Chem., 35, 171 (1984). KUgman, A.: J. Invest. Dermatol., 73, 39 (1979). Marks, R., Lawson, A., NichoUs, S.: Stratum Comeum, Springer Verlag, Heidelberg, p. 175, 1983. Takahashi, M., Machida, Y., Marks, R.: Arch. Dermatol. Res, 279, 281 (1987). Takahashi, M., Black, D., Hughes, B., Marks, R.: Chem. Exp. Dermatol., 246, 12 (1987). Grove, G. L., Kligman, A. M.: J. Geront, 38, 137 (1983). Marks, R. et al.: Br. J. Dermatol., 111, 265 (1984). Janson, L. H. et al.: Br. J. Dermatol., 107, 35 (1982). Roberts, D. et al.: J. Invest. Dermatol, 74, 13 (1980). Naito, N. et al.: Fragrance J., 16 (5), 4 2 ^ 6 (1988). Prince, L. M.: Preface, Academic Press, New York, 1977. Shinoda, S.: J. Jpn. Oil Chem. Soc. (Yukagaku), 37, 1012 (1988). Friberg, S. E.: Colloids and Surfaces, 4, 201 (1982). Lindman, B. et al.: Colloids and Surfaces, 3, 391 (1981). Gerbacid, W. E. et al.: J. Am. Oil Chem. Soc, 53, 101 (1976). Shinoda, K. et al.: J. Phys. Chem., 88, 5126 (1984). Higuchi, W. I. etal.: J. Pharm. Sci., 51, 459 (1962). Tomomasa, T.: J. Jpn. Oil Chem. Soc. 37, 1012 (1988). Shinoda, K. et al.: J. Colloids Interface Sci., 35, 624 (1971). Cockbain, E. G. et al.: J. Colloids Sci., 8, 440 (1953). Saito, H. et al.: J. Colloids Interface Sci., 24, 10 (1967). Griffin, W. C : J. Soc. Cosmet. Chem., 5, 249 (1954). Fukushima, S. et al.: J. Colloids Interface Sci., 57, 201 (1976). Barry, B. W. et al.: J. Colloids Interface Sci., 35, 689-705 (1971). Barry, B.W.et al.: J. Pharm. Pharmacol., 25, 244-253 (1973). Thomas, F. A. J. et al.: J. Pharm. Pharmacol., 20, 513-520 (1968). Thomas, F. A. J. etal.: J. Pharm. Pharmacol., 22, 417-422 (1970). Yamaguchi, M., Yoshida, K., Tanaka, M., Fukushima, S.: J. Electron Microsc, 31, 249-252 (1982). Kumano, Y. et al.: J. Soc. Cosmet. Chem., 5, 249 (1977). Mitsui, T.: J. Jpn. Oil Chem. Soc. (Yukagaku), 26 (10), 635 (1977). Powers, D. H.: Drug Cosmet. Ind., 82, 233 (1958). Czetch-Lindenwald, H. et al.: Pharm. Zentraih., 98, 362 (1959). Clor, E. J. et al.: J. Soc. Cosmet. Chem., 26, 337 (1975). Landen, K.: Am. Perform. Cosmet., 82, 77 (1967). Spir, H. W. et al.: Hautarzt, 7, 2 (1956). Zenisek, A. et al.: Biochim. Biophys. Acta., 18, 589 (1955). Yamaguchi, Y.: J. Jpn. Oil Chem. Soc. (Yukagaku), 39, 95 (1990). Ensminger, L. E. et al.: Soil Sci., 51, 125 (1948). Walker, G. F.: Clay Minerals, 7,129 (1967). Brindley, G. W. et al.: Am. Mineral, 49, 106 (1964). Plafikanov, D. et al.: Colloids Pohm. Sci., 255, 907 (1977). Park, A. C. et al.: J. Soc. Cosmet. Chem., 23, 3 (1972).

Skin care cosmetics 57. 58. 59. 60.

Takahashi, M. et al: ibid., 36, 177-187 (1985). Tojyo, K.: Pharmacia, 21, 1244 (1985). Elias, P. M.: J. Invest. Dermatol., 80, 4449 (1983). Stotts, J.: J. Invest. Dermatol, 69, 219 (1977).

369

2

Makeup cosmetics

2.1. History of makeup cosmetics Makeup cosmetics have an extremely long history. In olden times people daubed natural pigments and other substances on their faces and bodies for protective or religious purposes. And, a cosmetic palette for making up the eyes, thought to date back to around 10,000 BC, has been unearthed at an ancient Egyptian archeological site. It is considered that eye shadow, eyeliner and other items for accentuating the eyes were the main types of makeup in use at the time. In ancient Rome, it was the fashion for women to make their skin white and face powder was used for this purpose. In the Middle Ages, all classes of people used rouge and kneaded rouge was made for the cheeks and lips. In China, Japan and other parts of Asia the use of face powder and rouge was very common. During the Middle Ages, the use of makeup was criticized by certain people on moral grounds but in the 20th century it has come to be widely accepted in society. Early in the 20th century, organic colors were synthesized and used in lipsticks like those of today and manicure liquid, which was still uncommon at the time, was featured in Vogue magazine. In America in the 1940s, foundations were made to take over the role of face powder in giving the skin a beautiful and natural appearance. In the present day, makeup is made in many different fashion colors and a large variety of products, some of them varying in utility and others having functions suited to each season, are now being developed.

2.2. Types and functions of makeup cosmetics^ 9) The roles of makeup cosmetics are to make the user look more beautiful, protect their skin and have a psychological effect on them. Regarding the psychological effect, makeup cosmetics give the wearer a more definite feeling, make them more enthusiastic about doing things and feel good because putting on makeup is fun. They also give a sense of satisfaction to women who want to change their appearance^^^ The beautifying and protective functions of different types of makeup product are listed in Table 2.1.

370

Makeup cosmetics 371 Table 2.1. Functions of different makeup cosmetics Functions

Makeup item

Face powder (pressed powder)

1) 2) 3) 4)

Adjusts skin color and makes it brighter Makes the skin feel vibrant and gives a feeling of transparency Suppresses sweat and sebum so makeup lasts longer Protects skin from ultraviolet radiation

Foundation

1) 2) 3) 4)

Changes the skin color as desired Gives the skin luster, a feeling of vibrancy and transparency Covers up liver spots and freckles Protects the skin from drying and ultraviolet radiation

Lipstick

1) Applying color to the lips gives life to the face 2) Protects the lips from drying and ultraviolet radiation

Rouge

1) Applying rouge to the cheeks makes the person look cheerful and healthy 2) Improves facial form and gives relief to the face

Eyeliner

1) Making a line along the edge of the eyelashes emphasizes the contours of the eyes 2) Changing the appearance enhances the expression of the eyes

Mascara

Lengthening and curling the eyelashes emphasizes the eyes and the shading achieved gives them expression.

B 03

s

*o Eye shadow

Shading gives the eyes relief and expression to the face.

Eyebrow cosmetics

Adjusting the form of the eyebrows brings out the eyes

Nail enamel

1) Gives luster to the nails and expression to the hands and fingers 2) Strengthens the nails

Enamel remover

Removes enamel from the nails

Nail treatment

Restores nails which have become brittle and lost their luster through drying out and lipid loss to their normal condition

2.3. Types and forms of makeup cosmeticsi^-^^) Makeup cosmetics consist of many types of product in which various pigments (organic, inorganic, pearly pigments, etc.) are dispersed through a base formula. Great advances have been seen in the form and formulation of makeup cosmetics as time has gone on. There are now a great variety of different forms made for different functions, effects and convenience of use. Table 2.2 lists the main types, forms and constituents of makeup cosmetics^^^

2.4. Raw materials used in makeup cosmetics 14-24) The raw materials that are used for makeup cosmetics are such powders as coloring pigments, whitening pigments, extender pigments and pearly pigments, and the base

IY

Table 2.2. Types of makeup cosmetics and their constituents13)

Face powder and foundation

Category

.C

2 /

.-

2z $3

52

I

Oils/fats Waxes Fatty acids Higher alcohols Fatty acid esters Hydrocarbons Surfactants Metallic soaps Plasticizers High molecular con~pounds Inorganic thickeners Volatile oils (solvent) Polyhydric alcohols Inorganic powders I Purif~edwater

II

Organic coloring material Inorganic coloring material Pearly pigment

* Paper sheet-type face powder

0 0 ~ 1 0 0 0 O

(3 0 CJ 0 f j 13 5 f] 5 5

C_,

Rouge

1

1

Eyes Lipstick

Eyeliner

Mascara

Nails Nail enamel

Makeup cosmetics 373 Table 2.3. Powders used in makeup cosmetics Category

Raw materials

Extender pigment

Talc, kaolin, mica, sericite, calcium carbonate, magnesium carbonate, anhydrous silicic acid, barium sulfate, etc. (synthetic) Lithol Rubin B, Lithol Rubin BOA, Tetrabromofluorescein, etc. (natural) /^-carotene, carthamin, carmine, chlorophyll, etc.

Organic Coloring pigment

Red iron oxide, yellow iron oxide, black iron oxide, ultramarine, Prussian blue, chromium oxide, carbon black, etc.

Inorganic

Titanium oxide, zinc oxide,

Whitening pigment

Fish scale flake, bismuth oxychloride, titanium dioxide coated mica

Pearly pigment

Others

Metallic soap

Mg, Ca and Al salts of stearic acid, Zn salts of myristic acid, etc.

Synthetic polymer powder

Nylon powder, polyethylene powder, polymethyl methacrylate, etc.

Natural substances

Wool powder, cellulose powder, silk powder, starch powder, etc.

Metal powder

Aluminium powder, etc.

material that they are dispersed through. By varying the proportions of powder and base material various types of formula can be made. The base materials used include such oily substances as liquid paraffin, petrolatum, waxes, squalane and synthetic esters; humectants like glycerin and propylene glycol; and surfactants. Other raw materials include preservatives, antioxidants and perfumes. Covering and coloring ability are important functions of makeup cosmetics and their powder component is largely responsible for this. Table 2.3 shows the powders that are used in makeup cosmetics. Coloring pigments and whitening pigments are used to adjust the color shade and the covering ability. The hiding power of a powder is related to its refractive index and particle size. Table 2.4^5) shows the refractive indices for the main powders used. In makeup cosmetics, covering ability is provided by titanium dioxide and zinc oxide which have Table 2.4. Refractive indices of major powders^^^ Powder

Refractive index

Titanium dioxide (rutile) // (anatase) Zinc oxide White lead Barium sulfate Calcium carbonate Clay minerals (talc, mica, etc.) Alumina Silica

2.71 2.52 2.03 1.94-2.09 1.63'-1.64 1.51-1.65 1.56 1.50-1.56 1.55

(Kuwahara and Ando : Pigments and Colors, p. 26, Kyoritsu Zensho, 1972)

374 New cosmetic science

high refractive indices. A particle size of 0.2-0.3//m gives the maximum hiding power. The hiding power drops off both above and below this. Pearly pigments give a pearly luster to the color shade and change the quality of the feeling given. Extender pigments are used as a diluent for coloring pigments as well as to give extensibility and adhesion and absorb sweat and sebum. They also regulate the gloss of the finished makeup. Extensibility is the quality of spreading well on the skin and giving a feeling of smoothness. Talc and mica materials have this quality. These days, spherical powders having a particle size of 5-15//m are used to raise extensibility. These include spherical silica and alumina and spherical powders of such polymers as nylon, polyethylene, polystyrene and polymethylmethacrylate. This extensibility can be evaluated physically using the coefficient of kinematic friction. Table 2.526> lists the coefficients of kinematic friction for various powders. The smaller the coefficient of kinematic friction, the greater the extensibility. Adhesion is a quality indicating how well the powder will adhere to the skin. It also helps determine the feeling of the finished makeup and its lasting power. Formerly, metallic soaps were much used to enhance the adhesion but now adhesion is often achieved by applying surface treatment to the powder. Powders are also made water repellent to keep them in close contact with the skin and to prevent sweat from spoiling the makeup. Such substances as metallic soap, fatty acids, higher alcohols and silicone are used in the process to make powders water repellent. Another characteristic of powders is their absorption. This indicates their ability to absorb sweat and sebum. Their absorption gets rid of any oily luster and renders the makeup difficult to spoil. Makeup spoils more quickly for people who produce a lot of sebum and it is particularly prone to spoiling in the so-called "T zones" of the forehead and around the nose where there is a lot of sebum. Kaolin, calcium carbonate and magnesium carbonate are extremely good at absorbing sweat and sebum and making them finer enables them to absorb even more. Nowadays, porous powders are used because they are highly absorbent. Examples of porous powders are porous silica beads and porous cellulose powder which, because of their spherical nature, also enhance extensibility. Table 2.5. Coefficients of kinematic friction^^^ for powders Powder

Coefficient of kinematic friction

Talc Mica Kaolin Titanium oxide Fine particle titanium dioxide Zinc oxide Spherical silica Spherical alumina Spherical nylon Spherical polystyrene Spherical polymethyl methacrylate

0.27—0.33 0.42'-0.47 0.54-0.59 0.49 0.80 0.60 0.28—0.32 0.29 0.33 0.26-0.30 0.29

Makeup cosmetics

375

5.0 Fine particle ti tanium dioxide 4.0

3.0 42

Titanium\\ dioxide \ \

O

>

2.0

\ ' Zinc oxide Mica

rr250

1 — 350 300

400

450

Wavelength (nm)

Fig. 2.1. Capacity of powders to absorb UV radiation^^l A very important function of makeup cosmetics is to protect the skin against ultraviolet radiation. In this respect, titanium dioxide and zinc oxide have great covering capacity so they provide good protection against ultraviolet radiation but with consideration for how the finished makeup will look, not much should be used. Although makeup using a foundation may look good indoors, whiteness may show through when outside in strong sunlight. To prevent this from happening, foundations containing photochromic powders, whose color changes reversibly according to the amount of light, are being developed. However, fine particle titanium dioxide, which has an average particle size of around 0.03 jum, is not only an excellent ultraviolet screen but also transmits visible light well because of its fine particle size, as shown in Fig. 2.P^\ so the color applied will not appear whitish and the finished makeup will look natural. In addition to fine particle titanium dioxide, zinc oxide and zirconia are also used in makeup cosmetics to provide protection against ultraviolet radiation. Other raw materials will be discussed with reference to the individual products in which they are used.

2.5. Face powder and pressed powder Face powder is a type of cosmetic that has been in use since long ago for the purpose of changing the color of the face to make it more attractive and cover up liver spots, freckles and other such blemishes. However, since the advent of foundations, their main purpose has been to remove oily luster due to sweat and sebum and keep the makeup looking good for longer. Through the addition of pink or blue color, they are now also used to make a subtle change to the skin color, or, for the same effect as rouge on the cheeks.

376 New cosmetic science

In addition, there are multi-color molded powder products comprising two or more colors in a medium compact which produce a very novel effect in the makeup. There are different forms in which face powders are available. There is loose powder, in which powder is the main component; compact powder, a solid form in which a small amount of oil has been added as a binding agent; paper powder, in which the powder has been applied to paper; liquid face powder, in which powders are dispersed through an aqueous solution; and kneaded powder, which has glycerin or some other solution kneaded into it. Currently, loose powder and compact powder are the main types used. Liquid face powder and kneaded face powder were used much in the past but now they are used largely for stage and other types of special makeup. 2.5.7. Loose powder Loose powder is a powder-form product in which almost all the raw materials are powders and no oil is used. Loose powder is mainly applied on top of emulsion and oil-based foundations to achieve a matt, clear skin color by reducing oily luster and stickiness and keep the makeup looking good for longer by keeping sweat and sebum under control. As loose powder is applied using a puff, it must spread smoothly. With this in mind, the main powder used is generally talc. Kaolin and titanium oxide are used to give a matt finish and covering capacity, zinc stearate and zinc myristate for good adhesion, and calcium carbonate and magnesium carbonate to absorb sweat and sebum. Coloring pigments and pearly pigments are used to enhance the skin color. Typical formula. Loose powder Talc Kaolin Titanium dioxide Zinc myristate Magnesium carbonate Sericite Coloring pigment Perfume

% 75.0 5.0 3.0 5.0 5.0 7.0 q.s. q.s.

Manufacturing procedure Mix the talc and coloring pigment in a blender. Then add the remaining materials, mix well together and adjust the color shade. Spray in the perfume and mix in well. After grinding in a grinder, pass through a sieve. 2.5.2. Compact powder Compact powder has virtually the same function as loose powder. Loose powder is generally for use in the home while compact powder is used when away from home to touch up the makeup. The materials used to make compact powder are basically the same as those for loose powder but around 5% oil is added as a binding agent to make it into the compact form.

Makeup cosmetics IHl Typical formula. Compact powder Powders:

Talc Sericite Kaolin Titanium dioxide Zinc myristate Magnesium carbonate Coloring pigment Squalane Glyceryl tri-iso-octanoate Preservative, antioxidant Perfume

Binding agent: Other materials:

% 55.0 15.0 10.0 5.0 5.0 5.0 q.s. 3.0 2.0 q.s. q.s.

Manufacturing procedure Mix the talc and coloring pigment in a blender. Add the remaining powders, mix well together, add the binding agent and antioxidant and adjust the color shade. Spray in the perfume and mix in well. After grinding in a grinder, pass through a sieve and compress into the container. 2.5.3. Paper sheet-type face powder Paper sheet-type face powder is made by applying loose powder to paper to make it handy to carry around. It absorbs the sweat and sebum which appear on the skin and makes it easy to touch up the makeup. The raw materials used are virtually the same as those for loose powder but a watersoluble polymer is added to fix the powder on the paper. Powders are dispersed through a solution of a water-soluble polymer and this is applied evenly to the paper with a coater. The paper is then dried and cut to a suitable size for putting into a case. 2.5 A, Liquid face powder Liquid face powder is a light cosmetic which gives a cool and refreshing feeling. It is made by dispersing loose powder through a lotion containing glycerin, etc.. When used, it is shaken well to make it into a uniform mixture. It is best to use powders which settle uniformly and do not form suspensions or settle out. They should also not adhere to the sides of the bottle. The features of liquid face powder are its cool and refreshing feeling and its thinness as a makeup. 2.5.5. Other powder

cosmetics

(1) Baby powder Baby powder is used for infants. As it should be very smooth, absorb moisture and protect the skin, the main ingredient is talc. It also contains a germicidal agent to prevent diaper rash and the like. Being for infants it is important to select germicidal agents and perfumes which do not produce irritation. Baby powder comes in two forms. One is a loose powder in which powders are the

378 New cosmetic science

main raw materials and the other is a compact powder which contains around 5% oil as a binding agent. A typical baby powder formula is given below. Typical formula. Baby powder (loose powder type) Powders: Other materials:

Talc Zinc oxide Magnesium stearate Germicidal agent Perfume

%

93.0 3.0 4.0 q.s. q.s.

Manufacturing procedure Same as for loose powder. (2) Talcum powder Talcum powder is a cosmetic for use on the whole body and produces a very smooth feeling. As it absorbs sweat and moisture it is very good when used after a bath in summer or after shaving. It contains more talc than ordinary loose powders and metallic soap to improve adhesion. Germicidal agents and other substances are also added to achieve various purposes. Typical formula. Talcum powder Powders: Other materials:

Talc Magnesium stearate Germicidal agent Perfume

% 95.0 5.0 q.s. q.s.

Manufacturing procedure Same as for loose powder.

2.6. Foundations In the past, face powder was the main type of base makeup. But with the appearance of emulsion-form, cake-form, stick-form and other types of foundation as makeup cosmetics in the 1940s, the main functions of face powder became keeping the makeup looking good and touching it up. As foundations now have other functions, such as enhancing skin color, adjusting skin quality, covering liver spots and freckles, protecting the skin from ultraviolet radiation and other external stimuli, and treating skin conditions, they are currently considered separately from face powders. Although there are many different types of foundations they can be broadly divided into powder compact form, oil-based foundations and emulsion foundations (O/W or W/0 emulsion). Table 2.6 shows a classification of foundations by type along with their main features. In Europe and the United States, liquid cream foundations are the main type but, in Japan, the powder compact foundation are more common. In order to prevent the makeup from spoiling, powders which have been made hydro-

Makeup cosmetics 379 Table 2.6. Classification of foundations by type Constituents (%) xjpc

Characteristics

Powder

Oil

Powdery type

80-^93

7—20

Pharmaceutical agent

Enhances skin color, handy to carry around

Dual-use type

80-^93

7-20

Pharmaceutical agent

As above, can be used with or without water

Cake type

80—85

2-20

Emulsifier

For use with water. Gives a cool, refreshing feeling

Oily type

35'-60

40-65

Pharmaceutical agent

Good adhesion, water resistant

W / 0 emulsion type 1 5 - 5 5

30-70

5-30

Emulsifier, humectant

M a k e u p d o e s n ' t spoil, handy to carry around

0 / W emulsion type 10—25

15—30

40—70

Emulsifier, humectant

Spreads easily, good for treating skin conditions

W / 0 emulsion type 1 0 - 3 5

15—50

20-60

Emulsifier, humectant

Makeup doesn't spoil

0 / W emulsion type

10—25 50—80

Emulsifier, humectant

Spreads easily, good for treating skin conditions, moist feeling

15—50

Emulsifier, humectant

Makeup doesn't refreshing feeling

Compact type

Water

Creamy type

5—20

Liquid type W / 0 dispersed type 10-30

30—50

Others

spoil,

phobic through silicone treatment are included or a refreshing feeling is obtained through the use of a compact foundation with a wet sponge. Sunscreen foundations are now becoming very popular to protect the skin from ultraviolet radiation in summer. On the other hand, in winter when it is dry and cold, emulsion foundations which moisturize the skin are used. There is also a W/0 type emulsion foundation which contains wax. This is a solid-type emulsion foundation which is molded into a compact. For a foundation to be used in point makeup to cover liver spots, freckles and other blemishes, the oil-based type is most suitable as it has greater covering ability. 2.6.1. Powdery

foundations

A major type of powder compact foundation is the powdery foundation. After applying a foundation cream, powdery foundation is applied to the skin by putting a suitable amount on a sponge. As this makes it so easy to touch up the makeup when one is away from home, powdery foundation is widely used in Japan by people of all ages. Powdery foundation is composed of extender pigments, whitening pigments, coloring pigments, binding agents, perfumes, etc.. Extender pigments such as talc, mica and sericite are used to make them spread well and feel smooth to the touch. With consideration for making the finished makeup look beautiful and enhancing the skin color, powdery foundations contain more coloring pigments and whitening pigments than compact powder. Although the main types of coloring pigment used are iron

380 New cosmetic science

oxide inorganic pigments, high chroma organic pigments are also sometimes employed to make the skin color prettier and titanium dioxide coated mica (pearly pigments) to impart a suitable luster to the finished makeup. The oil used as a binding agent may be a natural animal or plant oil, a mineral oil such as liquid paraffin or a synthetic ester oil. Silicone oil is used to reduce the spread of the foundation and make it water repellent. To improve moldability, such semi-solid oils as lanolin or hydrocarbon waxes may be added. The amount of binding agent is determined with a view towards making the foundation as easy to use as possible for its designed purpose but the oil absorption characteristics of the powders used in it are also considered. The oil absorption characteristics indicate the ability to absorb oil. This is found by adding oil gradually to 100 g of powder and kneading it in. The amount of oil in ml which has been added at the point at which the mixture becomes a lump is the oil absorption of the powder. Oil absorption is a parameter indicating the physical properties of a powder. Typical formula. Powdery foundation Powders:

Binding agents:

Other materials:

Talc Mica Kaolin Titanium dioxide Titanium dioxide coated mica Zinc stearate Red iron oxide Yellow iron oxide Black iron oxide Nylon powder Squalane Lanolin acetate Octyldodecyl myristate Neopentylglycol octanoate Sorbitan mono-oleate Preservative, antioxidant Perfume

% 20.3 35.0 5.0 10.0 3.0 1.0 1.0 3.0 0.2 10.0 6.0 1.0 2.0 2.0 0.5 q.s. q.s.

Manufacturing procedure Same as for compact powder. 2.6.2. Dual-use foundations^^^ Dual use foundations are foundations which can be used either on a dry or a wet sponge and they are the main type of summer foundation. Their special features are their convenience, their cool, refreshing feeling and their ability to keep makeup looking good when used with a wet sponge. When powdery foundations are used with a wet sponge, the powders in them, being hydrophilic, absorb water causing them to cake which makes them difficult to use. In

Makeup cosmetics 381 dual-use foundations, this caking has been prevented by subjecting the powders to a process which makes them hydrophobic. The basic ingredients of dual-use foundations are silicone treated powders and binding agents. However, as they are mainly used in summer, they often contain ultra-fine titanium dioxide and ultraviolet absorbents to provide protection against ultraviolet radiation. Typical formula. Dual use foundation Powders:

SiHcone-treated talc SiHcone-treated mica SiHcone-treated titanium dioxide SiHcone-treated ultra-fine titanium dioxide SiHcone-treated red iron oxide SiHcone-treated yellow iron oxide SiHcone-treated black iron oxide Zinc stearate Nylon powder Squalane Solid paraffin Dimethyl polysiloxane Glyceryl tri-iso-octanoate Octylmetoxy cinnamate Preservative, antioxidant Perfume

Binding agents:

UV absorbents: Other materials:

% 19.2 40.0 15.0 5.0 1.0 3.0 0.2 0.1 2.0 4.0 0.5 4.0 5.0 1.0 q.s. q.s.

Manufacturing procedure Same as for compact powder. 2.6.3.

Cake-type

foundations

Cake-type foundations are a compact foundation used with a wet sponge. They are much used in summer because of the cool, refreshing feeling they give. This type of foundation contains a hydrophilic surfactant so that it becomes creamy when put on a wet sponge. The creaminess is due to the emulsion that is formed when it is mixed with water. This was the main type of foundation product for summer use before the advent of the dual-use type which has now taken over as the main type because of its convenience. However, it is still much used because, being used with water it refreshes and is good for people who like thin makeup. Typical formula. Cake-type Powders:

foundation Talc Kaolin Sericite Zinc oxide Titanium dioxide

% 43.1 15.0 10.0 7.0 3.8

382 New cosmetic science Red iron oxide Yellow iron oxide Black iron oxide Squalane POE sorbitan mono-oleate Isocetyl octanoate Isostearic acid Preservative, antioxidant Perfume

Binding agents:

Other materials:

1.0 2.9 0.2 8.0 3.0 2.0 4.0 q.s. q.s.

Manufacturing procedure Same as for compact powder. 2,6 A,

Oil-based

foundations

In this type of foundation, powders are dispersed through a base material consisting of oils. There is a compact and a stick form. They are suitable for autumn and winter because of their strong emollient effect. Among the features of oil-based foundations, they spread well on the skin, adhere well and makeup using them does not spoil easily. As this type of foundation has great covering ability, it is used cover up pronounced liver spots, freckles and birthmarks which ordinary foundations would not be able to hide. To prevent the sticky feeling which an oil-base tends to give, the formula must be designed in consideration of the individual characteristics of the oils and powders used. The following formulae are for a compact-type oily foundation and one with great covering ability. Typical formula 1. Oil-based foundation (compact type) Powders:

Binding agents:

Other materials:

Talc Kaolin Titanium dioxide Red iron oxide Yellow iron oxide Black iron oxide Solid paraffin Microcrystalline wax Beeswax Petrolatum Lanolin acetate Squalane Isopropyl palmitate Antioxidant Perfume

17.8 15.0 15.0 1.0 3.0 0.2 3.0 6.0 2.0 12.0 1.0 6.0 18.0 q.s. q.s.

Manufacturing procedure Make a solution of the binding agents and antioxidant at 85°C. Mix the powders together and after adequate mixing and grinding, add this to the solution while agitating. Using a

Makeup cosmetics 383

colloid mill, break up the powders and disperse them through the solution. Add the perfume, de-air, fill containers at 70° C and cool. Typical formula 2. Foundation for hiding blemishes (stick-type) Powders:

Talc Kaolin Mica Titanium dioxide Red iron oxide Yellow iron oxide Black iron oxide Solid paraffin Microcrystalline wax Petrolatum Dimethyl polysiloxane Squalane Isopropyl palmitate Antioxidant Perfume

Binding agents:

Other materials:

% 2.8 20.0 3.0 20.0 1.0 3.0 0.2 3.0 7.0 15.0 3.0 5.0 17.0 q.s. q.s.

Manufacturing procedure Same as for compact-type. 2.6.5, 0/W emulsion

foundations

An O/W emulsion foundation is a system in which the oil phase and the powders are dispersed through the water phase to form an emulsion. There is a cream type and a liquid type. As they give a moist feeling when used and are good for treating skin problems, they are the favorite type of foundation in Europe and America where the climate is dryer and the humidity is lower than in Japan. However, it is difficult to keep makeup looking good with them because they are easily affected by sweat and sebum. For an O/W type emulsion, the powders (pigments) must be uniformly dispersed through the water phase and a stable emulsion system must be maintained. Though moistness increases as the viscosity decreases, the most important thing to find out is how much the external phase viscosity can be reduced before the system becomes unstable. So, when designing formulae, it is necessary to carefully consider such points as the selection of the powders, the composition of the oil phase, selection of the emulsifier and emulsification and dispersion methods. The following formula is for the liquid type. This can be changed to the cream type by raising the proportion of the oil phase (internal phase) and increasing the quantity of powder. Typical formula. O/W emulsion foundation (liquid type)^^^ Powders:

Talc Titanium dioxide Red iron oxide

% 3.0 5.0 0.5

384 New cosmetic science

Water phase:

Oil phase:

Other materials:

Yellow iron oxide Black iron oxide Bentonite POE sorbitan monostearate Triethanolamine Propylene glycol Purified water Stearic acid Isohexadecyl alcohol Glyceryl monostearate Liquid lanolin Liquid paraffin Perfume, Preservative

1.4 0.1 0.5 0.9 1.0 10.0 56.4 2.2 7.0 2.0 2.0 8.0 q.s.

Manufacturing procedure Disperse the hydrophilic system thickening agent, bentonite, through the propylene glycol and add the purified water. After mixing this in a Homomixer at 70° C, add the rest of the water phase ingredients and mix adequately. To this mixture add the powders after adequate mixing; grind while stirring and then process in a Homomixer at 70°C. Next, make a solution of the oil phase ingredients heating to 70-80°C and add this gradually. Process in the Homomixer at 70°C. While stirring, cool to 45°C. Add the perfume and cool to room temperature. Finally, de-air and put in containers. 2.6,6, W/0 emulsion

foundations

The W / 0 emulsion foundation has been with us since long ago. The only drawback is that it feels sticky on use because the external phase is oil. However, the advent of silicone surfactants has enabled W / 0 emulsions with silicone oil as their external phase to be developed, which are highly stable. Foundations using this new type of W/O emulsion produce a more refreshing feeling and the makeup stays looking good, which is not usual with this type of foundation. Among this type, there is a 2-layer dispersed foundation (shake well-type). This foundation has a low viscosity and becomes a W / 0 emulsion when shaken. As it has a cool, refreshing and moist feeling, it is very popular in summer. Recently, a solid form of W / 0 emulsion foundation has been developed. This type of foundation is very popular as in addition to making beautiful makeup and being good for treating skin problems, it has the convenience of being in compact form. This is basically the cream type which has been made solid by the addition of wax and put in a container. Typical formulae for the W / 0 cream type and the 2-layer dispersed type are given below. Typical formula 1. W/O emulsion foundation (cream type)^^^ Powders:

Sericite Kaolin Titanium dioxide Red iron oxide

% 5.36 4.0 9.32 0.36

Makeup cosmetics 385 Yellow iron oxide Black iron oxide Liquid paraffin Decamethyl cyclopentasiloxane Polyoxyethylene denatured dimethyl siloxane Purified water Dispersing agent 1,3-butylene glycol Preservative Stabilizer Perfume

Oil phase: Water phase:

Other materials:

0.8 0.16 5.0 12.0 4.0 51.9 0.1 5.0 q.s. 2.0 q.s.

Manufacturing procedure After mixing the water phase ingredients together at 70° C, mix and grind the powders and add this to the water phase. Then process at 70°C in a Homomixer. Add the stabilizer, which has been dissolved in some of the purified water, and stir. Add the oil phase, which has also been heated to 70° C, and process in the Homomixer. While stirring, cool to 45°C and add the perfume. Cool to room temperature. Finally, de-air and put into containers. Typical formula 2, W/0 emulsion foundation (2-layer dispersed typep^^ Talc Titanium dioxide Silicic acid anhydride Nylon powder Coloring pigment Octamethyl cyclotetrasiloxane Pentaerythritol rosinate Neopentyl glycol di-iso-octanoate Squalane Glyceryl tri-iso-octanoate Poly oxy ethylene denatured dimethyl poly siloxane Purified water 1,3-butylene glycol ethanol

Powders:

Oil phase:

Water phase:

7.0 12.0 2.0 4.0 2.0 10.0 1.5 5.0 2.5 2.0 1.5 39.5 4.0 7.0

Manufacturing procedure Mix the water phase ingredients together and add the powders after mixing and pulverizing. Mix with a Homomixer. Make a solution of the oil phase ingredients; add this and mix with the Homomixer. Finally, de-air and put into containers.

2.7. Lipsticks and rouge31-37) 2.7.7. History

of lipstick^^-^^

At the time of the Greek and Roman empires, colors taken from certain plants were applied to the lips and cheeks. Following that, carmine (cochineal) taken from the cochi-

386 New cosmetic science

neal bug {Coccus cati L.) came into general use in western Europe and carthamin taken from safflowers in Japan. The modern stick-form lipstick composed of oils, fats and waxes did not appear until after the World War I. Carmine and carthamin continued to be used as the colors for lipstick but the synthetic color tetrabromofluorescein has now come into use recently enabling long-lasting lipsticks to be made. Since around 1940, synthetic colors have taken over from carmine and lipstick colors which can be matched to women's hairstyles and clothes are now very common. Recently, lipsticks have seen many innovations such as the use of powders with a pearly luster to produce a great range of tones and qualities and the making of emulsion types by including water and humectants in the base formula. 2.7.2, Quality requirements for lipsticks From the point of view of quality, lipsticks should satisfy the following conditions: (1) they should not cause irritation or harm to the lips (2) they should not have unpleasant taste or odor (3) they should go on smoothly, not smear and stay looking good for the required amount of time (4) they should retain their form with no breakage, deformation or softening during storage or use (5) they should neither sweat nor bloom (6) they should maintain their attractive appearance and there should be no change in the color 2.7.3. Raw materials of lipsticks Lipsticks consist mainly of an oily base material and coloring agents. In order to satisfy the above quality requirements, it is necessary to combine the raw materials effectively. (1) Oily base material Waxes which are solid at ordinary temperatures are used to provide the stick form of lipsticks. The waxes used are natural waxes such as carnauba wax, beeswax, candelilla wax and Japan wax, and mineral waxes such as solid paraffin, microcrystalline wax, ceresin and other hydrocarbon waxes. Oils used are those that are liquid at ordinary temperatures or whose melting points are around body temperature. Examples are such natural oils as cocoa butter, castor oil, jojoba oil, macadamia nut oil and lanolin oil; such hydrocarbon oils as petrolatum and liquid paraffin and synthetic fatty acid esters. Among them, castor oil, which has been in use for a very long time, gives the molded lipstick a proper viscosity. It is also important because it acts as the solvent for the staining dyes. In general, the natural ingredients used have a certain amount of polarity so they help to ensure the stability of the pigment dispersion. Among the often used oils, the natural waxes have particularly great hardening capacity. Because of such excellent characteristics, natural ingredients are used a lot in lipsticks but it is necessary to pay attention to sweating of the lipstick, due to the absorption of moisture by the raw materials, as well as rancidity'^^^ Recently a variety of new synthetic oils have been developed and are

Makeup cosmetics 387

widely used because they do not have the unpleasant oily smell of fats and oils derived from plant and animal sources and they are of uniform quality. Glycerides are an example of synthetic oils used in lipsticks, particularly triglycerides of which there are many. Special types of glyceride can be designed by varying the carbon numbers and the branch positions of the aliphatic acids. Ester oils other than glycerides, e.g. liquid waxes, are also widely used. Materials like octyldodecyl ricinoleate synthesized by imitating the structure of natural substances and polybutene, which have no polarity, are also utilized. In some cases, a small amount of a lipophilic non-ionic surfactant or other substance is added to ease the dispersion of colors through the lipstick base. Lipsticks are mainly composed of oily ingredients like the ones described above and recently, various kinds having a humectant function, have started to be used in consideration of the lips' moisture balance. In some lipsticks, an emulsion which directly incorporates water and a humectant in stable proportions is used in the base formula'^^^^^ In some others, ultraviolet absorbers and reflectors, and other pharmaceutical agents are added to protect the lips against ultraviolet radiation and from drying out. There are also lip creams in which no coloring agent is included in the lipstick base. (2) Coloring agents There are almost as many sets of cosmetic color regulations as there are countries in the world. The colors for lipsticks must therefore be selected from among those approved in the countries where they are to be sold. The synthetic organic colors are divided into dyes and pigments on the basis of their structures and properties. Pigments comprise color pigments and lake pigments which are made by converting dyes into insoluble form by combination with metallic compounds. Pigments determine the color of lipsticks. To improve the lasting power of the color on the lips, staining dyes are used as well. Examples of these dyes are tetrabromofluorescein, tetrachlorotetrabromofluorescein and dibromofluorescein. Castor oil is normally used for the dissolution of dyes but as the solubility is low, solvent oils may be used as well. They are butyl stearate, diethyl sebacate, tetrahydrofurfuryl alcohol and their acetate. To obtain different shades, a variety of inorganic pigments are used in addition to the synthetic organic colors. Titanium dioxide, red iron oxide, yellow iron oxide and black iron oxide are used to adjust the tone and brightness, and such pearly pigments as titanium dioxide coated mica and colored titanium dioxide coated mica to give a pearly luster. Other inorganic pigments are also used to give the lipstick good skin adhesion and the right quality. These days, the surfaces of inorganic pigments are treated using various methods in order to enhance their dispersion and stability. Typical formula 1. Oil-based lipstick % Titanium dioxide Lithol Rubin B Lithol Rubin BCA Tetrabromofluorescein Candelilla wax SoHd paraffin

5.0 0.6 1.0 0.2 9.0 8.0

388 New cosmetic science Beeswax Carnaubawax Lanolin oil Castor oil Cetyl octanoate Isopropyl myristate Antioxidant Perfume Manufacturing

5.0 5.0 11.0 25.2 20.0 10.0 q.s. q.s.

procedure

Add the titanium dioxide, Lithol Rubin B and Lithol Rubin BCA to part of the castor oil and grind in a roller mill (pigment component). Dissolve the tetrabromofluorescein in another part of the castor oil (dye component). Melt the other ingredients by heating and mix them together; then add the pigment and dye components, and stir in a Homomixer to obtain uniform dispersion. Pour into molds and cool immediately to make stick-form lipstick. Typical formula 2. Emulsion type lipstick^^"^ Titanium dioxide Lithol Rubin B Lithol Rubin BCA Tetrabromofluorescein Seresin Candelilla wax Carnauba wax Castor oil Glyceryl di-isostearate Polyoxyethylene(25)polyoxypropylene(20)2-tetradecyl ether Purified water Glycerin Propylene glycol Ultraviolet absorbent Antioxidant Perfume

% 4.5 0.5 2.0 0.05 4.0 8.0 2.0 30.0 39.95 1.0 5.0 2.0 1.0 q.s. q.s. q.s.

Manufacturing procedure Add the titanium dioxide, Lithol Rubin B and Lithol Rubin BCA to part of the castor oil and grind in a roller mill (pigment component). Dissolve the tetrabromofluorescein in the castor oil (dye component). Make a uniform solution at 80°C from the purified water, glycerin and propylene glycol (water phase). Melt the other ingredients by heating and mix; then add the pigment and dye components, and stir in a Homomixer to obtain uniform dispersion. Add the water phase and make into an emulsion in the Homomixer; then pour into molds and cool immediately to make stick-form lipstick.

2.8. Rouges (rouge, cheek color and blush-on products) Rouges are applied to cheeks to tint the face a shade of red and give a healthy complex-

Makeup cosmetics 389

ion. For this purpose, the main pigments used have been red ones but in the past few years, the range of colors has been expanded to include browns and blues. The forms of rouges are compact, liquid, cream and stick. The one in general use is the compact. The base formula is virtually the same as that for compact face powders and foundations. Normally, a definite color is not desired, rouges have less covering ability than foundations and the amount of coloring pigment in them is 1-6%. Dyes are not used because they will stain the skin. The quality requirements for rouges are as follows: (1) they should fit in well with foundations and it should be easy to smooth off the brush marks (2) there should be no change in color (3) they should have a suitable coverage, luster and adhesion (4) they should be easy to wipe off and should not stain the skin Typical formula 1. Compact rouge Talc Kaolin Zinc myristate Pigment Liquid paraffin Perfume Preservative

% 80.0 9.0 5.0 3.0 3.0 q.s. q.s.

Manufacturing procedure Mix the ingredients, except the perfume and the binder (liquid paraffin), together well, in a blender. Spray the binder and the perfume into the blender and then pulverize. Sieve and press. Typical formula 2. Oil-based kneaded rouge Kaolin Titanium dioxide Red iron oxide Lithol Rubin BCA Ceresin Petrolatum Liquid paraffin Isopropyl myristate Antioxidant Perfume

% 20.0 4.2 0.3 0.5 15.0 20.0 25.0 15.0 q.s. q.s.

Manufacturing procedure Add the kaolin, titanium dioxide, iron oxide and Lithol Rubin BCA to some of the liquid paraffin and grind in a roller mill (pigment component). Heat the other ingredients and stir them into a solution; then add the pigment component and obtain a uniform dispersion with a Homomixer. While stirring, cool to 50°C and put into containers.

390 New cosmetic science

2.9. Eye makeup^^) 2.9.L History and types Eye makeup has a very long history and eye shadow and eyeliner have been in use since the time of the ancient Egyptians. In Japan, eyebrows had been blackened for a long time but it is only comparatively recently that eye makeup has come into general use. The wide use of eye makeup spanning all age groups has come about as the result of changes in lifestyle and a heightened interest in fashion. There is a tremendous variety of eye makeup products. The application of eye makeup products makes the eyes more pronounced and gives them expression. If all combinations of base materials and different forms of eye makeup are taken into account there is a very large number of products. This section will also touch on removers and other special products which are essential to eye makeup. Eye makeup products comprise the following: (1) Eye makeup: eyeliner, mascara, eye shadow, eyebrow cosmetics. (2) Other special products: eye makeup remover, eye wrinkle care products, false eyelashes and adhesives. 2.9,2. Points for attention with eye makeup products As for other cosmetic products, it is very important to pay sufficient attention to safety. With regard to strictness of safety requirements, they can be ranked in order of their proximity to the mucous membrane of the eye as follows: eyeliner > mascara, eye shadow > eyebrow cosmetics When making formulae for them, attention must be paid to the following points: (1) Pigments. In Japan, because of the color of the eyes, eyelashes and hair, the colors normally used for eyeliner, mascara and eyebrow cosmetics are blacks, grays and browns but in the case of eye shadow, bright pinks, purples, blues, greens and colors with a pearly luster are also used. In Europe and the United States, there is a much wider range of colors due to the tremendous variety of eye, eyelash, hair and skin colors. The major pigments used for eye makeup are inorganic pigments like black, red and yellow iron oxides; ultramarine and carbon black and extenders like talc and kaolin and pearly pigments like titanium dioxide coated mica. The colors used in cosmetics sold in a particular country must be approved in that country and it is necessary to keep in mind that the regulations regarding colors are different in each country. (2) Measures against microbial contamination. Measures should be taken against microbial contamination, as there is the chance that eye makeup may go into the eyes. In order to do this, it is necessary to consider hygiene control at all times, from the raw materials stage, through the production stage, to the time that they come on to the user's hands to be applied to the eyes. With water based eyeliners and mascaras which contain natural

Makeup cosmetics 391 and synthetic film formers and thickeners, special care should be taken if they are the type in which the brush is kept in the case because it is so easy for microbes to multiply in these conditions. (1) Raw materials stage: sterilization to prevent microbial contamination of the powders and other raw materials (especially in the case of natural materials). (2) Production environment and processes: arrange environment and processes so that contamination is prevented during production. (3) Containers and other packaging materials: sterilization. (4) Microbial resistance of product: measures against secondary contamination at time of use (base formula, include preservative in formula). Although the above apply to all cosmetics, the regulations in every country concerning microbial contamination are particularly strict in the case of eye makeup cosmetics. 2.9.3.

Eyeliner

Eyeliner is applied along the upper and lower hairlines of the eyelashes with a fine brush to emphasize the impression given by the eyes and make them more attractive. The following types of eyeliner are available on the market: f Film type (Water-based ] I Liquid form \ [ Non-film type Oil-based Solid form

Powder compact type Pencil type

Although there are many types of liquid-form eyeliner, in all types pigments are dispersed through a low viscosity liquid in such a way that no settling of pigments occurs. They come in glass bottles, metal or plastic tubes with an attached brush. The quality requirements for eyeliners are as follows: (1) There must be absolutely no irritations as they are applied at the edge of the eyes. (2) They must dry quickly (particularly in the case of people with double folded-in eyelids for whom it would be unpleasant if drying were slow as the eyes must be closed until the eyeliner has dried). (3) They should be easy to apply. (4) The film should have flexibility. (5) The finished eye makeup should look attractive. (6) The makeup should last well; it should not peel off, smudge or crack. (7) It should be waterproof and not be spoiled or come off with sweat or tears. (Special waterproof and water-resistant types especially for use when in the water should not come off when swimming). (8) There should be no precipitation or separation of pigment. (9) There should be no microbial contamination. The main constituent of the film type, which is much used in Japan, is a polymer emulsion. After application, when the water in the formula vaporizes, a continuous film with a luster forms on the skin. As the film is insoluble in water, the eyeliner does not

392 New cosmetic science run with sweat or tears and it can be removed as one piece by wetting with remover. This type is called a "peel-off-type". Typical formula 1. Film-type eyeliner Black iron oxide Polyvinyl acetate emulsion Glycerin Polyoxyethylene sorbitan mono-oleate Carboxymethyl cellulose (10% aqueous solution) Acetyltributyl citrate Purified water Preservative Perfume

% 14.0 45.0 5.0 1.0 15.0 1.0 19.0 q.s. q.s.

Manufacturing procedure Add the glycerin and polyoxyethylenesorbitan mono-oleate to the purified water and heat to dissolve the ingredients. Then add the black iron oxide and grind in a colloid mill (pigment component). Heat the other ingredients together to 70°C, stirring. Add the pigment component to this and disperse evenly using a Homomixer. In the formulation of this type, the most important thing is the selection of the polymer emulsion. So, it should be chosen with consideration for the eyeliner's usability and should thus enable the eyeliner to be put easily on the brush, should not make the skin feel tight, and should remain even and last well. It should also be highly safe. Care is needed because some polymer emulsions on the market contain types of surfactants, anticorrosives, preservatives and monomers which would be undesirable for cosmetics. Attention must also be paid to differences in regulations from country to country. Other constituents are chosen with the same degree of stringency but, in aqueous systems, it is easy for them to interreact chemically and coagulate, making pigments prone to precipitation. Freezing may cause irreversible changes so severe high and low temperature tests should be carried out. Furthermore, because it is so easy for microorganisms to multiply in aqueous systems, attention must also be paid to sterilization during manufacturing. Polyhydric alcohols prevent freezing and assist in preservation. There is also the non-film type water-based liquid-form eyeliner which contains water soluble polymers and triethanolamine salts of higher fatty acids but no polymer emulsion. As the points for attention are the same as for the film type, an explanation is not given. Although this type is not water-resistant, like the peel-off film type, its advantage is that there is little feeling of tightness in the skin, making it feel more comfortable. The brush-pen and felt pen types are special forms of eyeliner. With them a thin, natural line can be drawn and they are easy to use even by people unaccustomed to using cosmetics. Typical formula 2. Felt pen type eyeliner Pigment: Dispersant:

Carbon black Polyoxyethylene(10)dodecyl ether

% 5.0 2.0

Makeup cosmetics 393

Humectant: Purified water: Preservative: Perfume:

Glycerin

10.0 83.0 q.s. q.s.

Manufacturing procedure After dissolving the dispersant in the water, add the carbon black and grind in a ball mill. The ratio of powder to water, size of the ball and quantity ratio between the powder base and the ball will greatly affect the grinding efficiency. Add the preservative and perfume to some purified water and use this to dilute the pigment dispersion produced by grinding. The special feature of this eyeliner is its extremely low viscosity which prevents clogging of the brush tips and the felt pen. For ease of application, eyeliner must have a low viscosity. As a guide, the viscosity should range from several to 10 cps. In order to lower the viscosity of the contents, techniques for inhibiting pigment precipitation are required. In accordance with Stokes Law, if the viscosity is constant, we should use pigments with lower specific gravities, and reduce the size of the pigment particles. In this respect, carbon black, Prussian Blue and organic pigments are often used because they have low specific gravities, they are easy to grind and have good coloring. In the product design, polymer emulsions used in the formulations for mascaras and liquid eyeliners are added to give water resistance and prevent smudging. An example of equipment suitable for the grinding is the ball mill. The pencil type is much used because of its ease of use. As its formulation is similar to that of the eyebrow pencil, please refer to the section on eyebrow pencils for details of this. In the case of the eyeliner pencil, it is important to make the lead a little finer in order to make the color go on well and give a soft feeling. 2.9A. Mascara^^^ Mascara is used to make the eyelashes look attractive. It can be broadly divided into the following types: f Water-based

{ Liquid form <^ [ Oil-based [ Solid form

Film type [ Non-film type

Nowadays the solid type is hardly used at all but the cream and liquid forms, in which the brush or stick are incorporated in the container (called automatic container in Japan), are used frequently. In Japan, film types and those containing a film former are popular and types containing 3-4% of natural or synthetic short fibers are a great favorite because the eyelashes can be made to look very long with them (called Longlash Type). The quality requirements for mascara are as follows: (1) They should be non-irritating as they are applied so close to the eyes. (2) They should go on evenly and should not harden the eyelashes or form blobs.

394 New cosmetic science

(3) (4) (5) (6) (7)

They should make the eyelashes look thick and long. They should make the eyelashes curl effectively. They should have an appropriate luster. They should have an appropriate drying time. When dry they should not go on to the lower eyelids and their appearance must not be spoiled by sweat, tears or rain. (8) They should be easy to remove. (9) They should be easy to use throughout their period of use. (10) There should be no contamination by microorganisms. However, as the degree of importance of these requirements varies with the type of eyelashes and individual preference, it is difficult to make one type of product which will satisfy everyone, so there are several different types on the market. The viscosity of the mascara and the brush and other aspects of the container contribute greatly to the differences between product types. Furthermore, peoples' eyelashes vary. They have different lengths, thicknesses, degrees of fineness and grow upwards or downwards. In Europe and North America, oil-based mascara has developed as a main type. The lack of popularity of this type in Japan is probably due to race-related differences in eyelash types. Europeans and North Americans have long, fine eyelashes which grow upwards in a closely packed fashion, whereas most Japanese have thick, short eyelashes which grow downwards in a loosely packed fashion, so if the average Japanese uses oilbased mascara, it goes on to the lower eyelids which does not look very well. However, recently oil-based mascaras which do not go on to the lower eyelids have been developed. Preferences for mascara, of which there is tremendous range, are thus partly determined by such differences in eyelash types. Also influencing this is whether they can be used with false eyelashes or not. Typical formula. Oil-based waterproof mascara Black iron oxide Polyacrylate ester emulsion Solid paraffin Lanolin wax Light isoparaffin Sorbitan sesquioleate Purified water Preservative Perfume

% 10.0 30.0 8.0 8.0 30.0 4.0 10.0 q.s. q.s.

Manufacturing procedure Add the black iron oxide to the purified water and make a dispersion using a homogenizing mixer; then add the polyacrylate emulsion and heat to 70°C (water phase). Mix the other ingredients together and heat to 70°C (oil phase). Add the water phase to the oil phase and make a uniform emulsion using a Homomixer. As the formula for water-based mascara is basically the same as that for an waterbased eyeliner, with increased proportions of wax and thickener, it is not given here.

Makeup cosmetics 395 Cellulose derivatives and bentonite are examples of much used organic thickeners, and inorganic thickeners, respectively. Though the solid type of mascara was much used in the past, it is not so common now so no description is given. The cream type is now prevalent. 2.9.5. Eye shadow Eye shadow is applied to eyelids and corners of the eyes to create shadow and produce a sense of relief in order to emphasize the beauty of the eyes. Eye shadow has a greater variety of colors than any other eye makeup. The colors range from the normal ones of blues, violets, browns and grays to the more vivid ones like greens, oranges and pinks. In order to make these colors, colored titanium dioxide coated micas (pearly pigments), which have increased in number in recent years, are used in addition to conventional inorganic pigments, and a luster is also given to give greater variety to the sensation of color quality. Through the use of hydrophobically treated pigments, there are now eye shadows which have great lasting power. The formulations are basically the same as those for foundations. The different types of eye shadow are as follows. The main type is the powder compact in which the eye shadow has been pressed into a container. (Oil-based Liquid-paste form I [ Emulsion type (W/0 type, 0/W type) f Powder compact Solid form

\ Oil-based stick form ^ Pencil type

The following are the quality requirements for eye shadows: (1) They should be easy to apply smoothly and have good skin adhesion. (2) They should have no oily luster when applied. (3) There should be no change in color. (4) They should not be smudged by sweat or sebum and maintain a good appearance. (5) They should be highly safe as they are used around the eyes. Typical formula 1. Compact powder type Powders:

Binders: Other materials:

Talc Mica Sericite Pigment Pearly pigment Preservative Liquid paraffin Methylpolysiloxane Sorbitan sesquioleate Antioxidant Perfume

%

45.0 15.0 5.0 15.0 10.0 q.s. 6.0 2.0 2.0 q.s. q.s.

396 New cosmetic science

Manufacturing procedure Mix the powders well in a blender, make a uniform solution of the binders and other materials and mix this into the powders. Pulverize and press. Typical formula 2. Emulsion type "70

Powders:

Talc Kaolin Pigment Stearic acid Isopropyl myristate Liquid paraffin Propylene glycol monolaurate Antioxidant Perfume Purified water Butylene glycol Glycerin Preservative Triethanol amine Sequestering agent

Oil phase:

Water phase:

10.0 2.0 5.0 3.0 8.0 5.0 3.0 q.s. q.s. 56.8 5.0 1.0 q.s. 1.2 q.s.

Manufacturing procedure Mix the powders in a blender and pulverize. Make a solution of the water phase ingredients at 70-75°C. Make a second solution of the oil phase ingredients at 70-80°C. Add the pulverized powders to the water phase solution and stir to mix. Add the oil phase solution to this pigment dispersion while stirring, and disperse using a Homomixer. Stir and cool to room temperature. In the liquid type eye shadow, C10-C15 light isoparaffins are mainly used as the base material to which waxes and pigments are added. This type is highly water resistant. For the liquid type it is necessary to pay attention to adjustments for ease of application, system stability, container airtightness, drying of the contents with use, etc. For the stick type, a solution of liquid oils and waxes is made by heating, pigments are dispersed through the solution and this is poured into a metal mold and cooled, which is similar to the way in which lipsticks are made. To ensure an appropriate spread, hardness and good adhesion to the skin, it is important to select the most suitable oils, fats and waxes. They must also be made so that there is no sweating, blooming or rancidity, and they must not break during use. 2.9.6, Eyebrow

cosmetics

Eyebrow cosmetics are used after adjusting the form of the eyebrows with razors or scissors or by plucking out hairs to draw in the desired form, to make them darker in color or brighter. The most common are the easy-to-use pencil and mechanical pencil types but there are also powder compact and liquid types. The pencil and mechanical pencil types are made by kneading a solid wax and oil base with pigments. In the case of the powder compact type, a small amount of binder is added and the powder mixture is pressed into

Makeup cosmetics 397 a tablet form or poured into a compact container to be applied with a brush. The liquid type consists of pigments dispersed through an oil or emulsion system. It is packed in a container which includes a brush. The most common color in Japan is dark brown, followed by black and dark gray. There are also eyebrow products in light colors to make overly thick eyebrows appear thinner. The quality requirements for eyebrow cosmetics are as follows: (1) They should feel soft on the skin and go on evenly. (2) The line drawn with them should be clear and thin. (3) The makeup should last well without spoiling. (4) They should have high stability. There should be no sweating, blooming, breakage or crumbling. (5) They should be highly safe. Typical formula 1. Eyebrow pencil Black iron oxide Titanium dioxide Talc Kaolin Japan wax Stearic acid Beeswax Hydrogenated castor oil Petrolatum Lanolin oil Liquid paraffin Antioxidant

% 20.0 5.0 10.0 15.0 20.0 10.0 5.0 5.0 4.0 3.0 3.0 q.s.

Manufacturing procedure Mix the black iron oxide, titanium dioxide, talc and kaolin well together in a blender (powder component). Mix the other ingredients together, heating; then add the powder component, knead well in well and mold into lead. Put into a wooden casing. Typical formula 2. Powder compact-type eyebrow makeup Titanium dioxide Red iron oxide Yellow iron oxide Black iron oxide Talc Lanolin wax Liquid paraffin Glyceryl monostearate Perfume

% 20.0 20.0 20.0 15.0 10.0 10.0 4.0 1.0 q.s.

Manufacturing procedure Mix the titanium dioxide, iron oxides and talc well together in a blender (powder com-

398 New cosmetic science

ponent). Heat to melt and mix the other ingredients together. Then mix in the powder component evenly, pulverize and press. 2,9.7. Other products (1) Eye makeup remover. There are different types of eye makeup remover to remove the different types of eye makeup. The main types are for removing water and oil-based makeup. In the formulae for them, adequate attention must be given to safety. They should not be rubbed into the skin too strongly because this could lead to irritation. (1) Water-based. Made from purified water and a few other ingredients matched to the constituents of tears. The liquid type is the main one and as it has a non-oily feeling when used, it may be used after an oil-based remover. (2) Oil-based. Similar to oil-based eye makeup base. This type includes no pigment and ranges from liquid to gel form. It dissolves eye makeup in order to remove it. Its ability to remove makeup has been enhanced by adding volatile oils to the formula. Besides safety, another important consideration for this type of remover is the selection of oils with cleansing ability and a non-oily feeling. (2) Eye wrinkle care products. The skin around the eyes becomes dry more easily than that on any other part of the face. If the skin is left in a dry condition this will cause wrinkles, especially in winter. To prevent this, one should use eye wrinkle care products which have a humectant effect. There are several types of this product available. Some are oil-based ones whose formulations are similar to those of lip creams and lipsticks (stick type), and some are emulsion types (creams and milky lotions). (3) False eyelashes. False eyelashes are made by attaching human hair or nylon fibers to a piece of yarn and are stuck on the lash strip using the adhesive supplied with them. There are a great variety on the market with different lengths, shapes and thicknesses. The adhesives used are generally natural rubber latex compositions with very strong adhesion.

2.10. Manicure preparations56-60) 2.10.1. Functions and types^^-^^^ Like hair, nails are modified epidermal tissue and have keratin, a type of protein, as their main constituent. Their main purpose is to protect the area at the ends of the fingers and toes. (Refer to Chapter 2 in General for a description of the structure and constituents of nails). Healthy nails grow at an average rate of about 3 mm per month. Manicure preparations are cosmetics which protect the nails and make the fingers look attractive. Fig. 2.2 shows the order in which manicure products are used along with their purposes, while Table 2.7 highlights the different types of nail care products and their functions28'29).

Nails vary from person to person: they are thick, thin, large, small, long, short, flat or

Makeup cosmetics 399

Purpose

< Order of use>

Nail care

Care of nails and finger tips

Base coat

Fills in the grooves in the nails Improves adhesion

Enamel

Colors the nail

Top coat

Enhances luster, durability

Nail dryer

Speeds up drying and gives a luster to the nail enamel

Enamel remover

Nail care product

i

Base coat

--H

i

Nail enamel

|

Top coat

i

Nail dryer

; Enamel remover

Removes the enamel

Fig. 2.2. Purposes of manicure products and order of using them.

curved and their physical properties vary also. Nail hardness depends on the water content of the nail plate and composition of the keratin forming it. Generally speaking, children have soft nails which have high elasticity whereas adults have harder nails which break more easily^^\ Manicure preparations thus play a very important role in nail treatment and making the nails look more beautiful. 2.10,2. Nail enamel In terms of composition, present nail enamels belong to the nitrocellulose lacquer group. This is the most practical type that has been developed so far. As well as forming a durable film which protects nails, nail enamel makes them look more beautiful and is thus an indispensable part of modern beauty treatments. Nail enamel has come into common use because it easy to use and gives a nice luster to the nails. It would be very difficult to apply color to the nails using powders or pastes. 2.10.2.1. Quality requirements for nail enamel (1) It should have a viscosity permitting easy application to the nails. Table 2.7. Types of nail care product and their functions Product Nail treatment Cuticle remover Nail guard Nail polish Nail bleach Nicotine remover

Function • • • • • • • •

Supplies oil to compensate for water and oil removal by solvents Has humectant effect Tidies up the cuticle Reinforces the nail Prevents splitting and breaking Makes the nail surface smooth and gives it a luster Whitens the nail Removes nicotine

400 New cosmetic science

(2) (3) (4) (5) (6)

It should dry quickly (3-5 min.) and form an even film. The film should not be cloudy or have pin holes in it when dry. Pigments should be evenly dispersed and the prescribed color and luster should be maintained. The nail enamel should adhere well and not come off during daily activities. It should be easy to remove with enamel remover and come off cleanly. It should not damage the nails or be toxic to them.

2.10.2.2. Main ingredients of nail enamel The main ingredients of nail enamels satisfying the above requirements are listed in Table 2.8. Film formers. The best film former for nail enamel is nitrocellulose. Regarding the quality of nitrocelluloses in current use, the viscosity of most of them ranges from 1/21/4 s and the nitrogen content from 11.5-12.2%. They dissolve easily in ester and ketone solvents. The physical properties of the films formed also make them suitable for use in the paint industry. Needless to say, as the presence of free acid will have a deleterious effect on nail enamel products, the nitrocellulose must be refined. Furthermore, when handling nitrocellulose, care must be taken to keep it away from naked flames and sources of heat. Resins. Resins are an essential ingredient of nail enamel. By itself, nitrocellulose is lacking in terms of adhesion and luster. When used together with nitrocellulose, resins greatly enhance the adhesion and luster. Examples of resins in general use are alkyd resins, sulfonamide resins, sucrose resins and acrylic resins. In the selection of resins, attention must be paid to their interaction with coloring agents, compatibility with nitrocellulose and solubility in the solvents. Plasticizers. Plasticizers are used to give flexibility and durability to the film of enamel. In earlier times, castor oil and camphor were used for this purpose but nowadays, citric acid esters such as acetyl-tributyl citrate are more widely used. However, as camphor is such an effective plasticizer for nitrocellulose, it is still in use today. The required qualities for plasticizers are as follows: (1) They should have good compatibility with solvents, nitrocellulose and other resins. (2) They should be only slightly volatile and give plasticity to the enamel film. (3) They should be stable and not produce a bad smell. Table 2.8. Main ingredients of nail enamels^^^ Film forming ingredients

Solvents

— — Film formers — Resins — — Plasticizers — 1— Active solvents — Couplers or latent solvents — — '— Diluents — Coloring materials

Coloring agents '— Pearly pigments Suspending agents —— Thickeners

Nitrocellulose Alkyd, acrylic, sulfonamide resins, etc. Citric acid esters, camphor, etc. Ethyl acetate, butyl acetate, etc. Isopropyl alcohol, butanol, etc. Toluene, etc. Organic pigments, inorganic pigments, dyes, etc. Synthetic pearly pigments, natural fish scales, aluminium powder, etc. — Organic cation-modified clays

401

Makeup cosmetics Table 2.9. Types of solvent for nail enamel Solvent

Solvent type Low boiling point (up to 100°C) Active solvent Can dissolve nitrocellulose by itself

Medium

boiling

point (100~140°C) High boiling point (140~170°C) Very high boiling point (140-^170°C)

Function (in enamel)

Acetone, ethyl acetate, methylethyl ketone

Reduces viscosity speeds up drying

Butyl acetate, cel- Ester solvent losolve, methylisobutyl ketone

Prevents cloudiness giving fluidity

Ethyl lactate, dia- Ketone solvent cetone alcohol, cellosolve acetate

Enhances adhesion

Butylcellosolve, carbitol

Prevents cloudiness

Couplers or latent solvents

Has affinity for nitrocellulose but no dissolution capacity by itself

Diluents

No ability whatso- Toluene, xylene ever to dissolve nitrocellulose by itself

Ethyl alcohol. butyl alcohol and other alcohols

fluidity

and

by

and

Alcohol solvents

Mix with active solvent to enhance dissolution Improves feeling on use

Hydrocarbon solvents

Mix with active solvent to enhance ability to dissolve resins Regulates feeling on use

(4) They should be compatible with the pigments used. (5) They should be non-toxic. Attention should be paid to these points in deciding on a suitable plasticizer and the amount to be used. Solvents, Solvents used in nail enamel must dissolve nitrocellulose, resins and plasticizers, their viscosity must be able to be adjusted to give the appropriate feeling on use and they must have a suitable rate of vaporization. If the solvent dries too quickly, this will produce pin holes and brush marks will remain, which will affect the appearance of the finished film. Furthermore, solvents whose latent heat of vaporization is very high will cause cloudiness. Therefore, attention must be paid to all of these points. As there is no one solvent which satisfies all of the requirements regarding pin holes, cloudiness, drying rate and feeling on use, a mixture of different solvents is normally used. Such solvents can be broadly divided into the categories shown in Table 2.9. Coloring agents, colors and pigments. Dyes such as Rhodamine B, organic pigments such as Lithol Rubin BCA and inorganic pigments such as titanium dioxide, are used to give a sense of opacity and an attractive color to the finished manicure film. Natural fish scales and synthetic pearly pigments are also used to give a good appearance to the finished film. Suspending agents. Suspending agents are used to enhance the stability of the dispersion for nail enamels using inorganic pigments like titanium dioxide and larger pearly pigments. The suspending agents normally used are organically modified clays^^) which

402

New cosmetic science

prevent precipitation by making the enamel base thixotropic. Organically modified clays are made by exchanging the ions between layers in a clay like bentonite, for organic cations, which makes it lipophilic and easier to disperse in the solvent. Typical formula. Nail enamel Nitrocellulose (1/2 s) Alky d resin Acetyl tributyl citrate Ethyl acetate Butyl acetate Ethyl alcohol Toluene Pigment Suspending agent

% 10.0 10.0 5.0 20.0 15.0 5.0 35.0 q.s. q.s.

Manufacturing procedure Add the pigment to a mixture containing part of the alkyd resin and part of the acetyl tributyl citrate, kneading well together (pigment component). Make a solution of the other ingredients and add the pigment component to this, mixing well to form a uniform dispersion. Of particular importance in the manufacturing process are, carrying it out in a sealed container to prevent evaporation of the solvents, and doing it away from naked flames and sources of heat. Recently, W/O emulsion nail enamels have also been developed^^\ There are base coats for filling in the grooves in nails and improving adhesion, and top coats which are applied on top of the enamel to enhance luster and durability. With the exception of the pigments and suspending agents, they are composed of basically the same ingredients as nail enamels but modifications have been made to enhance their functions. 2,10.3. Enamel remover Enamel remover consists of a mixture of solvents capable of dissolving nitrocellulose and resins. There are types which contain moisturizers and water to replenish the moisture and fat removed by the solvents, and there is also a cream-type enamel remover. Typical formula. Enamel remover Acetone Ethyl acetate Butyl acetate Lanolin derivative Purified water Dye Perfume

% 66.0 20.0 5.0 1.0 8.0 q.s. q.s.

As the ingredients of enamel remover are highly inflammable it is necessary to take adequate precautions against naked flames during manufacture.

Makeup cosmetics 403

2.10.4. Nail treatment When nail enamel and enamel remover are used repeatedly, it is important to remember to take care of the nails and the finger tips. Products referred to as nail treatments are used for this purpose. There are milky lotion and cream types and one in a pencil-shaped tube which is particularly easy to use. They are most effective when used before going to bed, after removing the enamel from the nails, putting the hands in warm soapy water and drying them completely. The frequency of use depends on the condition of the nails. It is a good idea to use nail treatment 2-3 times a week.. Typical formula. Nail treatment Stearic acid Microcrystalline wax Petrolatum Hydrogenated lanolin Liquid paraffin Polyoxyethylene(5)oleate Propylene glycol Triethanol amine Clay Purified water Preservative Perfume

% 2.0 3.0 7.0 2.0 22.0 2.0 5.0 1.0 0.3 55.7 q.s. q.s.

Manufacturing procedure After dissolving the propylene glycol and triethanol amine in the purified water, add the clay and make a uniform dispersion, heating to 70°C (water phase). Mix the other ingredients, heat to dissolve and maintain at 70°C (oil phase). Add the oil phase to the water phase to make the preliminary emulsion and then use a homogenizing mixer to achieve a uniform one. After making the emulsion, cool to 30°C while stirring. 2.10.5. Other products (1) Cuticle remover. Cuticle remover is a cosmetic product used to remove the old cuticle and dirt on the nail plate, in order to keep the nails looking attractive. One type contains weakly alkaline ingredients such as sodium phosphate and triethanol amine, while another contains a scrub powder so it has a physical mode of action. Typical formula. Cuticle remover Triethanol amine Glycerin Purified water Perfume

% 10.0 10.0 80.0 q.s.

Special care must be taken to ensure that cuticle remover does not go into the eyes, on to other parts of the body or on to clothing.

404

New cosmetic science

(2) Nail guard. This is a cosmetic product which strengthens thin and soft nails, prevents cracking and chipping and makes the enamel last longer. In one type, polymer powders (as strengthening agents) and nylon fibers are added to the enamel base coat (3) Nail drier. Nail drier speeds up the drying of nail enamel and gives it an extra luster. It is usually in aerosol form and consists of a small amount of nail drier base and a large amount of propellant. Various oils may be used in the nail drier base. (4) Nail polish. Nail polish is applied to the nails and then they are polished in with chamois leather to keep them in a healthy condition by filling in the grooves, making them smooth and giving them a shine. It also makes the enamel film more durable and gives the nails a greater luster. The main ingredients are inorganic powders and a small quantity of pigment is used to give the nails a healthy color. It comes in powder, paste or compact form. (5) Others. Examples of other manicure products are nicotine remover and nail bleach, a similar product, for making the nails whiter. Such products are not seen on the market any more.

References 1. Sugiura, Ueda, ed.: Modern Cosmetic Science, Hirokawa Shoten, 1974. 2. Kobo, T., ed.: Modern Products Encyclopedia, Toyo Keizai Shimposha, 1986. 3. Soc. Cosmet. Chem. Jpn., ed.: Latest Developments in Cosmetic Science, enlarged and improved edition, Yakuji Nipposha, 1988. 4. Bourgeois, C : Chimie de la beaute, Que sais-je No. 901, Presses Universitaires de France, Paris, 1970. 5. Schrader, K.: Grundlagen und Rezepturen der Kosmetika, Hiitig Buch Verlag GmbH, Heidelberg, 1989. 6. Balsam, M. S. et al.\ Cosmetics Science and Technology, Vols. 1,2, 2nd edn., John Wiley and Sons Inc., New York, 1972. 7. Schlossman, M. L.: Cosmetics and Toiletries, 100, 33-40 (1985). 8. Sperandio, G. J.: Am. Perfum. Cosmet., 79, 75-77 (1964). 9. Kimura, S. et al.: Cosmetics and Toiletries, 107, 59-68 (1992). 10. Saito, Murai, Date: Fragrance J., 73, 10 (1985). 11. Hempel, M.: Seifen-Ole-Fette-Wachse, 120, 5, 262-264 (1994). 12. Kuhni, M. et al.: Parfumerie und Kosmetik, 75 (9), 581-582, 587 (1994). 13. Tanaka, S., Kumagaya, S.: Cosmetics and Industry, 40 (6), 115 (1987). 14. Faulkner, E. B.: Cosmetics and Toiletries, 107, 45-49 (1992). 15. Hofmann, B.: Seifen-Ole-Fette-Wachse, 116 (8), 299-306 (1990). 16. Charlet, E.: Kosemetik International, No. 2 (64), 69-70 (1991). 17. Schlossman, M. L.: Cosmetics and Toiletries, 105, 53-64 (1990). 18. Tichy, H. S.: Seifen-Ole-Fette-Wachse, 117 (10), 389-392 (1991). 19. Brown, M. W. et al.: Cosmetics and Toiletries, 105, 69-73 (1990). 20. Griebler, W. D.: Seifen-Ole-Fette-Wachse, 113 (20), 765-771 (1987). 21. Tichy, S.: Seifen-Ole-Fette-Wachse, 118 (10), 612-620 (1992). 22. Bews, I. C. R. et al.: Am. Perfum. Cosmet., 79, 89-103 (1964). 23. Veitch, J.: Parfumerie und Kosmetik, 75 (2), 92-99 (1994). 24. Fukui, H. et al.: Cosmetics and Toiletries, 96, 3 7 ^ 6 (1981). 25. Kuwahara, Ando: Pigments and Paints, p.26, Kyoritsu Zensho, 1972. 26. Higashikubo, K.: Fragrance J., 14 (5), 60-66 (1986). 27. Jimbo, M., ed.: Powders, their Functions and AppUcations, p. .301, Japan Standards Association, 1991. 28. Kobayashi, S.: Fragrance J., 20 (1), 107-113 (1992). 29. Yoneyama et al.: Patent: Tokkaisho, 61-293904, Japan.

Makeup cosmetics 405 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67.

Someya et al:. Patent: Tokkaihei, 2-142716, Japan. Nowak, G. W.: Am. Perfum. Cosmet., 7 9 , 4 1 ^ 5 (1964). van Ham, G. et al.: Fette, Seifen Anstrichmittel, 76 (5), 223-228 (1974). Scrofani, C. et al.: Cosmetics and Toiletries, 108, 65-68 (1993). Krueger, C.: Cosmetics and Toiletries, 96, 35-36 (1981). Dweck, A. C : Cosmetics and Toiletries 96, 29-32 (1981). Dweck, A. C. et al.: Cosmetics and Toiletries 96, 61-72 (1981). Reuschl, W.: Parfiimerie und Kosmetik, 75 (2), 86-91 (1994). Haruyama, Y.: History of Makeup, pp. 22, 30, 107-125, Heibonsha, 1976. Inubai, T. et al.: Everything You Need to Know About Cosmetics for Your Beauty, pp. 62, 69, 86-88, International Commercial Press, 1978. Haruyama, Y. Collection: The History of Cosmetics in Our Daily Lives, pp. 30-36, 45, Heibonsha, 1987. Pola Culture Research Institute Collection: Japanese Cosmetic Tools and Heart Patterns, pp. .30, 40-42, Pola Culture Research Institute, 1989. Makabe, J.: Safflower Reverie, Yamagata Shimbunsha, 1978. Uemura, R.: Dyeing and Weaving in Life, No. 2, pp. 37-39, Senshoku to Seikatsu Sha Corp., 1973. Coloring Materials Association: Coloring Materials Technology Handbook, p. 318, Asakura Shoten, 1989. Ikeda, T.: Fragrance J., 18 (8), 41-45 (1990). Ikeda, T.: Fragrance J., 20 (4), 14-21 (1992). Patent: 1374048, Japan. Patent: 1307890, Japan. Patent: Tokkaisho, 56-45045, Japan. Patent: Tokkaihei, 03-76284, Japan. Patent: 1461702, Japan. Patent: Tokkohei, 01-287011, Japan. Nakajima et al: Patent: Tokkosho, 61^2328, Constituents of OilAVater Emulsions, Japan. Fishbach, A. L.: Am. Perfum. Cosmet., 79, 47-50 (1964). Kosmetik International No. 4, 58-59 (1992). Wimmer, E. P. et al.: Cosmetics and Toiletries, 107, 115-120 (1992). Kunzmann, T.: Seifen-Ole-Fette-Wachse, 103 (1), 5 ^ (1977). Schlossman, M. L.: Cosmetics and Toiletries, 96, 51-54 (1981). Grizzo, S.: Cosmetics and Toiletries, 92, 63-65, (1977). Kosmetik International No. 3, 65-68 (1995). Achten, G.: Am. Perfum. Cosmet., 79, 23-26 (1964). Kosmetik International No. 5, 40-41 (1995). Yamazaki, A.: Nail Care and Nail Art, pp. 6-11, Nagaoka Shoten, 1986. 25 ans Elegance Book No. 12 — Cosmetics 2 (supplementary issue), Fujin Gaho Sha, 1988. Yamazaki, K.: Fragrance J., 14 (4), 16-20 (1986). Ikeda,T., Kobayashi, T., Tanaka, C , Fujiyama, Y., Ozawa, T., Mitsui, T.: J. Soc. Cosmet. Sci. Jpn., 22 (1), 25-34 (1988). Yamazaki, K., Tanaka, M.: J. Soc. Cosmet. Chem. Jpn., 25 (1), 33-50 (1991).

3

Hair care cosmetics

3.1. Hair cleansing cosmetics Hair cleansing cosmetics consist of shampoo and rinse (rinse-off conditioner) which remove dirt from the scalp and hair, and keep it in a clean condition. The washing of a textile has been completed once the dirt has been removed and the textile has been dried but in the case of the human body, it is not just enough to remove the dirt: the feeling one has during and after washing the hair, and the care given afterwards, are also very important. Therefore, after washing the hair with a shampoo, a rinse is used to make it easy to manage. The type of dirt, nature of the detergent used, temperature at the time of washing and the physical forces acting, are all involved in the hair washing process. The dirt consists of sebum secreted by the scalp, sweat residue, flakes of superfluous horny layer flakes (dandruff), dust and other external matter, and the residue from hair care cosmetics which have fulfilled their designed purpose. In order to remove such dirt, anionic, amphoteric and nonionic surfactants are normally used as the detergents for shampoos. The dirt is removed by the penetration, emulsifying and dispersive actions of surfactants. First of all, the shampoo penetrates into the interface between the dirt and the surfaces to be washed (scalp and hair) and weakens its adhesion. As a result, the dirt can be easily removed by physical forces and is taken off by the water. The dirt is broken up into fine particles, uniformly dispersed in the water and the surfactant that adsorbed the dirt prevents it from adhering to the hair and scalp again. The lather of the shampoo plays a very important role because it keeps the shampoo in the hair, makes the hair easy to wash by easing the passage of the fingers through it and has a cushioning effect which prevents the hairs from getting tangled up with each other. There is not necessarily a correlation between lathering ability and cleansing ability, however. For instance, nonionic surfactants do not have much lathering ability but they are very good cleansers because of their strong emulsifying capability. Nowadays though, shampoos are not just for removing dirt from the hair and scalp, and they have been greatly diversified. There are now conditioning shampoos which prevent damage to the hair during washing, medicated shampoos which prevent dandruff and itchiness, and shampoos which incorporate rinses. If a rinse is used after washing the hair, its main ingredients of a cationic surfactant and oils are adsorbed by the hair and stay on it when the rinse has been washed off to improve the condition of the hair. Among hair rinses, there is a special type known as 406

Hair care cosmetics 407

"hair treatment" or "hair pack" which protects the hair more. It is used in the same way as other rinses. 3.1.1.

Shampoo

Shampoo is a hair-wash cosmetic used to remove dirt from the scalp and the hair, treat dandruff and itchiness and maintain the hair in a clean and beautiful condition. In order to do this, it must have an appropriate level of cleansing power which is sufficient to remove all the dirt but will not remove too much sebum, which is very necessary for the scalp and hair. There are a great variety of shampoos which, in addition to their main function of cleansing, have added value in the form of conditioning, luster enhancing and styling capabilities. These shampoos come in many different types and forms. 3.1.1.1. Qualities required of shampoos and their categories Although shampoos have many different functions they must all have the following qualities. (1) They must have an appropriate cleansing ability. (2) They must produce a lasting, rich, creamy lather. (3) They must protect the hair from friction damage during washing. (4) The hair must have a natural luster and an appropriate softness after it has been washed. (5) They must be very safe with respect to the scalp, hair and eyes. Formerly, soap was used for washing the hair. Then in the 1930s, as a result of advances made in the development of synthetic detergents, alkyl sulfates started to be used as detergents for shampoos in America and Europe. In Japan, powder and jelly form shampoos based on alkyl sulfates came in to use from 1955 onwards. With the introduction of alkyl ether sulfates beginning in 1965, the use of shampoo spread on a grand scale and liquid shampoo became the main type. From its external appearance, shampoo is divided into two types — a transparent liquid type and a high grade opaque liquid type, in which an opacifying agent is added. Some types of shampoo have additional functions. Examples are given below. (1) Oil shampoo and cream shampoo, in which an oil component has been added to enhance the feeling obtained after the hair has been washed. (2) Conditioning shampoo which prevents damage to the hair during washing. (3) Anti-dandruff shampoo which is very effective in preventing dandruff and itchiness. (4) Mild shampoo which is less irritating to the scalp and the hair. (5) Two-in-one type shampoo incorporating a rinse function as well (reduces friction on the surface of the hair, prevents static electricity, protects the hair, etc.). (6) Shampoo having a combination of the above functions. 3.1.1.2. Main ingredients of shampoo. Shampoo consists of foaming detergents and various additives. The foaming detergents used are anionic, amphoteric and nonionic surfactants.

408

New cosmetic

science

(1) Anionic surfactants. Anionic surfactants are used very widely as a foaming detergent for shampoo. The major ones are as follows: Alkyl sulfates (AS) and polyoxyethylene alkyl ether sulfates (AES) ROSO.M

AS

RO (CII,CII,())n S(),M

AKS

M : Sodium etc

Owing to their low price and high availability, sodium, ammonium and triethanolamine salt surfactants are the ones most used in shampoo. These surfactants are neutral, have high cleansing power, are stable in hard water and have a lathering ability satisfying a shampoo's needs. Very often AS and AES are used in combination. The former is low in price and produces a good lather while the latter is more hydrophilic, very soluble in water at lower temperatures and less irritant. The lathering, irritancy and hydrophilic nature can be adjusted as appropriate by varying the length of the alkyl and polyoxyethylene chains. Acyl methyl taurates (AMT) RCONCH2CH2SO3M CH3

M *. Sodium etc

Attention has been focused on acyl methyl taurate because its structure is similar to that of taurocholic acid, a naturally occurring surfactant found in the bile of humans and animals and it is now used as a highly safe surfactant. As the hydrophilic group is sodium sulfonate, it has high acid and hard water resistance. Based on the results of research carried out on the skin irritation, protein denaturation, adsorption to protein and cleansing power aspects of anionic surfactants^^ we can say that acyl methyl taurate is superior to other surfactants in that it does not readily leave a residue on the scalp and hair, it does not denature proteins, which are, of course, the main constituents of the scalp and hair, and it does not disrupt the normal metabolism of the skin. //-Acyl glutamate RCONHCOOM CH.CH.COOH

M:Sodmmetc

There are also amino acid surfactants, whose raw materials are amino acids, and they have sodium and triethanolamine salts. Compared to AS and AES, they have a somewhat lighter lather and they are very mild in terms of irritation with respect to the skin and the eyes. Soaps are also used as cleansing agents but they are not very good for shampoo because metallic soaps form with calcium and magnesium from water and the human body making the hair stiff. (2) Amphoteric surfactants. Amphoteric surfactants are used in combination with anionic surfactants to make the shampoo safer and to enhance thickening and so forth. They are also used on their own.

Hair care cosmetics 409 Betaine type Alkyl betaine

CH3

I

R-N^-CH2C00-

I

CH3

Alkylamide betaine CHs

I

RCONH(CH2)3 N+-CH2COOI CH3

Imidazolinium betaine ^N

R-<

-CH2

I

^N:-CH2 CH2CH3OH CH2C00~

Imidazolinium betaine normally exists as a 5-membered ring compound as shown above but it is really a complex mixture of substances as a result of cleavage of the Imidazolin rings. Though it has less lathering and cleansing ability than anionic surfactants, it has been used a major base material for baby shampoo for a very long time because of its low irritation, especially with respect to the eyes. (3) Nonionic surfactants. Nonionic surfactants act as a lathering enhancer and are used to supplement the effect of anionic surfactants. Fatty acid alkylolamides Monoethanolamide RCONHCH2CH2OH

Diethanolamide RCON

CH2CH2OH CH2CH2OH

Fatty acid alkylolamides are widely used to enhance lather stability, the thickening of the shampoo base formula and stability at low temperatures (prevention of freezing and solidification). (4) Shampoo additives. In addition to their main constituents, which have been described in the foregoing, shampoos also contain various additives which will be described in the following. As examples of oily ingredients, there are lanolin derivatives, liquid paraffin, higher fatty acids, higher alcohols, ester oils and silicones. Cationic polymers such as cationic cellulose are widely used as conditioning agents. When the shampoo becomes diluted, complex salts of the cationic polymer and surfactant are deposited on the hair^'^^ so that the fingers pass through it very freely during washing and rinsing. This action of cationic polymers is very effective in preventing damage to the hair during washing.

410 New cosmetic science In addition, depending on the purpose of the shampoo, such humectants as glycerin, thickening agents (polymer compounds), thickeners, opacifying agents, colors, stabilizers (sequestering agents), ultraviolet absorbents, preservatives and pH adjusters are also added. The following pharmaceutical agents are added to prevent dandruff and itchiness: triclocarban, sulfur, salicylic acid, zinc pyrithione (Z-pt) and isopropyl methyl phenol. The following are two typical formulae for shampoos. Typical formula 1. Transparent liquid shampoo Sodium polyoxyethylene (3) lauryl ether sulfate (30% aqueous solution) Sodium lauryl sulfate (30% aqueous solution) Coconut fatty acid diethanolamide Glycerin Perfume Color Preservative Metallic ion sequestering agent, pH adjuster: Purified water

% 30.0 10.0 4.0 1.0 q.s. q.s. q.s. q.s. 55.0

Manufacturing procedure Heat the purified water to 70°C, add the other ingredients, make a uniform solution and cool. Typical formula 2. Conditioning

shampoo

Triethanolamine polyexyethylene ether sulfate (30% aqueous solution) Sodium polyoxyethylene lauryl ether sulfate (30% aqueous solution) Sodium lauryl sulfate (30% aqueous solution) Laurie acid diethanolamide Lauryl dimethylaminoacetic acid betaine (30% aqueous solution) Cationic cellulose Ethylene glycol distearate Protein derivative Perfume Preservative Metallic ion sequestering agent, pH adjuster Purified water

% 10.0 20.0 5.0 3.0 7.0 0.2 2.0 0.5 q.s. q.s. q.s. 52.3

Manufacturing procedure Add the cationic cellulose to the purified water and heat to 70°C while stirring. Then add the other ingredients stirring to dissolve. On cooling, pearl-like crystals are formed. In this shampoo, the cationic cellulose is included as a conditioning agent to allow the fingers to pass freely through the hair on rinsing, while ethylene glycol stearate makes the shampoo opaque giving it a beautiful pearl-like appearance. 3.1.2.

Rinses

Rinses are a cosmetic product used after washing the hair to give it a smooth feeling and

Hair care cosmetics 411

adjust its surface condition. When soap was used for washing the hair, rinses made acidic through the addition of citric acid were used to remove the alkali and metallic soaps. Acidic rinses are still in use today for permanent waving and coloring the hair. Rinses consisting of a dispersion of fats and oils or hair cream in water (called oil rinses) are used to replenish the hair's oil when too much is removed during washing. Rinses having cationic surfactants as their main ingredients first made their appearance when alkyl sulfates and polyoxyethylene alkyl ether sulfates started to be used on a greater scale. Nowadays, the main types of rinse are the milky lotion and cream types made by adding various oils to gels formed from cationic surfactants and higher alcohols, "hair treatment" or "hair pack" is a special type of rinse in which the rinsing function has been enhanced. This type of rinse is used in the same way as ordinary rinses by applying to the hair and then rinsing off. 3.1.2.1. Functions of rinses The following is the extent of our knowledge regarding the adsorption of cationic surfactants on to the hair^^ When adsorbed on to the hair, cationic surfactants reduce the coefficient of friction of the hair surface and this effect is enhanced, the longer the alkyl chains are. To reduce the coefficient of friction of the hair's surface it is enough for a single layer of cationic surfactant molecules to be adsorbed on to the hair surface. It is thought that the hydrophilic group of the cationic surfactant faces towards the hair and is adsorbed on to it electrostatically, while the lipophilic group is oriented outwards (oriented adsorption). As a consequence, the hair's surface is covered by lipophilic groups making it smooth. Furthermore, once the cationic surfactant and oil have been adsorbed on to the hair, it is not easy to remove them by rinsing with water so the effect of a rinse is largely the same, regardless of whether the hair is rinsed lightly or very thoroughly. The following functions of rinses are achieved through the adsorption of cationic surfactants and oils on to the hair's surface and the formation of a hydration layer in the hydrophilic group component. (1) The surface of the hair becomes smoother enabling the hair to be brushed or combed more easily. (2) Static electricity is prevented. (3) The hair surface is protected. (4) The hair becomes softer and is given a natural sheen. 3.1.2.2. Ingredients of rinses (1) Cationic surfactants. A typical example is alkyltrimethylammonium chloride. CH3

I

R - N ^ -CH3

I

CH3

CI-

412 New cosmetic science Alkyl groups used range from Ci6 to C22. The dialkyl chain type, di-alkyl-dimethyl ammonium chloride is also used. (2) Oil component. Examples of substances used for the oil component are hydrocarbons, higher alcohols, esters and silicones. Silicones are especially effective in making the hair smooth. (3) Humectants. Some of the humectants used are glycerin, propylene glycol, 1,3butylene glycol, and polyethylene glycol. Humectants make the hair feel soft and moist. There are two types of hair rinse — a transparent liquid type and a white turbid emulsion type. However, for transparent rinses in which oils are solubilized in aqueous solutions of cationic surfactants, there are limitations on the types and quantities of oils that can be included and currently the main type used is the white turbid emulsion. They are described below. If cationic surfactants, higher alcohols and water are mixed together, a gel with a lamellar structure is formed^). So, if oils are added to this system to form an emulsion, a milky or creamy rinse with minute oil droplets dispersed through the gel can be obtained. When the rinse is applied to the hair and then washed off, a thin protective layer of oil remains on the hair. In hair treatment and hair pack, the types and quantities of the oils have been arranged so that they have a better rinsing function than ordinary rinses. Typical formula. Rinse Silicone oil Liquid paraffin Cetyl alcohol Stearyl alcohol Stearyltrimethylammonium chloride Glycerin Perfume, color, preservative Purified water

% 3.0 1.0 1.5 1.0 0.7 3.0 q.s. 89.8

Manufacturing procedure Add the stearyltrimethylammonium chloride, glycerin and color to the purified water and heat to 70°C (water phase). Mix the other ingredients together, heat to melt and keep at TC'C (oil phase). Add the oil phase to the water phase and emulsify in a Homomixer; then cool while stirring. 3.1.3. One-step shampoo (shampoo having both shampoo and rinse functions) Incorporating the basic rinse functions of reducing the coefficient of friction of the hair, preventing static electricity build-up and protecting the hair, one-step shampoo represents a further advance on conditioning shampoo. This product was developed for convenience in a changing lifestyle, particularly among young people, in which people wash their hair more often, whether for pleasure or business purposes. Amphoteric and anionic surfactants are employed as the major detergents for one-step

Hair care cosmetics 413

shampoo. The main conditioning agents used are cationic surfactants, silicones and their derivatives and other hydrocarbon oils. It is known that combining cationic surfactants with anionic surfactants in set proportions mitigates the irritation experienced when cationic surfactants are used by themselves and produces a very good rinsing effect^'^\ When cationic and anionic surfactants are mixed together, a complex which is insoluble in water usually forms. However, if anionic surfactants with hydrophilic groups in their molecules, in addition to the terminal ones, are used together with cationic surfactants, this forms a complex which is water soluble^\ Consequently, shampoos having amphoteric surfactants as their main cleansing agent can utilize this type of anionic-cationic complex as their rinsing agent. In the case of shampoos that use ordinary anionic surfactants as their principal cleansing agent, the cations and anions will bond together and be deposited reducing the effectiveness of any cationic surfactant used, so silicones are used as the main conditioning agent. Typical formula. One-step shampoo Imidazohnium betaine-type amphoteric surfactant Coconut fatty acid diethanolamide Stearyltrimethylammonium chloride Sodium A^-lauroyl-A^-methyl-/?-alanine SiUcone derivative Polyoxyethylene alkylpolyamine Perfume, color, pH adjuster Purified water

% 16.0 4.0 2.0 1.0 1.0 1.0 q.s. 75.0

Manufacturing procedure Add the stearyltrimethylammonium chloride and amphoteric surfactant, heat to dissolve and keep at 70°C. Dissolve the other ingredients and cool.

3.2. Hair growth promoters 3.2.1.

Introduction

Hair growth promoters are preparations made by adding various pharmaceutical agents to an alcohol-water solution which is applied to the scalp to normalize its functions. By increasing the circulation in the scalp, they improve hair follicle function which promotes hair growth and prevents hair loss. They also help prevent dandruff and itchiness. With the current aging of society, we can expect demand for hair growth promoters to increase year by year, and in keeping pace with this, new pharmaceutical agents for promoting hair growth and preventing hair loss should be continually developed. However, the development of truly revolutionary hair growth promoters will require a fundamental clarification of the mechanisms for hair growth and hair loss, the steady search for effective pharmaceutical agents and scientific proof for their effectiveness in humans.

414 New cosmetic science

3.2.2, Types of hair growth promoter Depending on the type and amount of active ingredient in them and their efficacy, hair growth promoters are classified as cosmetics, quasi drugs, OTC products and ethical pharmaceutical products. In Japan's Pharmaceutical Affairs Law, the indications of hair growth promoters classified as cosmetic products are stated as the prevention of dandruff, itchiness and hair loss whereas those for quasi drug products are stated as promotion of hair growth (new and existing hair), hair tonic, prevention of thinning hair, dandruff, itchiness and hair loss. Preparations for Alopecia areata, hypoplasia, seborrhoic alopecia and alopecia pityrodes and other hair loss requiring medical treatment are out of the scope of quasi drugs and should be treated as ethical pharmaceutical products. However, as male pattern baldness is not a medical condition, quasi drugs and OTC products are now used to prevent hair loss. In fact, these products probably owe their existence to this type of baldness. In a notice issued by Japan's Pharmaceutical Affairs Bureau, it is stated that as a rule, quasi drugs for preventing hair loss should be in liquid form and that the cream form is not acceptable^\ 3.2.3. Causes of hair loss The factors currently considered to cause hair loss are listed below. 3.2.3.1. Reduced hair follicle function due to male hormones In general, the thinning of the hair that men are so concerned about starts at the parietal region of the head or the front of the head and gets progressively worse with age. This is known as male pattern baldness or androgenic alopecia^^^ This type of baldness is different from alopecia areata and other medically-related hair conditions in that it is not due to any disease of the skin or the hair follicles^^^ After the hair starts to thin there is no change in the number of hairs on the total surface area of the head^^), but they become progressively finer, shorter and more brittle. The hairs become more brittle due to a reduction in the growth period of the hair cycle^^^. It was Hamilton who demonstrated the involvement of male hormones in male pattern baldness. In the early 1940s, he advocated that the causes of male pattern baldness were male hormones and genetic factors based on epidemiological findings^^^. The following inferences have been made regarding the relationship between male hormones in the hair follicles and metabolism in the hair root cells. The male hormone testosterone is converted to 5a-dihydrotesterone (DHT), a substance with higher biological activity, at the hair follicles through the action of Sa-reductase^^'^^^ It is currently thought that the action of DHT is the principal cause of hair loss. Although the details of the mechanism by which this happens are unclear, it is not thought that DHT acts directly but that in the cells, it bonds to a receptor (special type of protein), is transported into the nucleus where it activates a specific gene which induces the production of a certain type of protein, and this protein inhibits hair growth^^-^''^ Though we still know very little about the hair follicles' DHT receptors, it is considered that the conversion of testosterone to DHT is the first step in the hair loss process and as a result, compounds

Hair care cosmetics 415

that inhibit the action of 5a-reductase have been receiving attention as possible pharmaceutical agents for hair growth promoters. 3.2.3.2. Reduction in metabolic functions of hair follicles and hair bulbs It is the division, proliferation and differentiation of the hair matrix at the hair roots which form hair and make it grow up to the epidermis. The hair matrix receives the supply of nutrients that it requires for cell division from the capillaries in the dermal papilla. During the growth period, the basket-shaped network of capillaries extending 1/3 of the way up the hair follicles from the bottom help the hair to grow by supplying blood to the them. The development of the network of capillaries surrounding the dermal papilla and hair follicles has thus been of great importance to hair growth. So if the flow of blood in the capillaries surrounding the hair follicles and dermal papilla is reduced, the supply of nutrients to the dermal papilla and hair matrix will not be sufficient, hence impairing cell metabolism and having an adverse effect on hair growth. 3.2.3.3. Reduction in scalp physiological functions Excessive build-up of dandruff flakes will block the pores of the scalp through which hairs exit the epidermis. This will have an adverse effect on the hair production at the hair root and the substances formed when the dandruff is decomposed by bacteria will irritate the scalp giving rise to such conditions as pityriasis accompanied by itching and inflammation. Leaving this untreated will cause the hair loss to spread giving rise to the condition known as pityriasis type hair loss^^^ Furthermore, if the sebaceous glands in the upper part of the hair follicles secrete too much sebum, this will produce irritation to the scalp when decomposed by the bacteria on it and may give rise to seborrhoic alopecia. 3.2.3.4. Local impairment of circulation due to tension in the scalp A loss in flexibility in the scalp will cause a reduction in the flow of blood in the peripheral blood vessels in the subcutaneous tissue of the scalp adversely affecting hair growth^^). The result will be something close to the situation described in the section on reduction in metabolic functions of hair follicles and hair bulbs. In addition to the foregoing, the following causes of hair loss can be given: deficient diet, stress, drug side effects, genetics. 3.2.4. Active ingredients of hair growth promoters Table 3.1 lists the pharmaceutical agents currently used in hair growth promoters according to their actions. Stipulations are made in Japan's Pharmaceutical Affairs Law regarding the types and amounts of the above pharmaceutical agents which may be used, so the types of agent, and permitted quantities of each, are balanced together within the scope of the act in order to achieve the best hair growth promotion effect. Among pharmaceutical agents which dilate the capillaries, there are those which act on the vascular nervous system such as Swertia extract (swertinogen), vitamin E and its derivatives, benzyl nicotinate and carpronium chloride, and those which invigorate the

416 New cosmetic science Table 3.1. Pharmaceutical agents used in hair growth promoters Action Circulation improvement Local stimulation Hair follicle invigoration Anti-male hormone Anti-seborrhea Horny layer dissolution Sterilization Anti-inflammatory Others

Pharmaceutical agent Swertia extract (swertinogen), vitamin E and its derivatives, benzyl nicotinate, Tincture of chilly (capsium annuum linne), tincture of cantharis (Spanish Fly), camphor, vanilyl amide nonylate Hinokitiol, placenta extract, photosensitizer, pantothenic acid and its derivatives Estradiol, estrone Sulfur, thioxorone, vitamin B6 Salicylic acid, resorcinol, Salicylic acid, hinokitiol, benzalkonium chloride, photosensitizer Glycyrrhetic acid and its derivatives, menthol Amino acids, vitamins, crude drug extracts

circulation by local stimulation such as tincture of chilly (capsium annuum linne), tincture of cantharis (Spanish Fly) and vanilyl amide nonylate. Some of the pharmaceutical agents used to enhance hair follicle function are hinokitiol and placenta extract. Having a sterilizing action, hinokitiol also prevents dandruff. Pharmaceutical agents having an anti-male hormone action are estradiol and estrone, while sulfur, thioxorone and vitamin B^ are used for their anti-seborrhea effect. Having horny layer dissolution and sterilizing actions, salicylic acid, resorcinol and benzalkonium chloride prevent dandruff. Glycyrrhetic acid and its derivatives and menthol are used to prevent inflammation in the scalp. Amino acids, vitamins and crude drug extracts are included in hair growth promoters to supplement the supply of nutrients to the follicles and invigorate enzyme activity. 3.2.5. Methods of evaluating hair growth promoters As shown in Table 3.2, the methods of evaluating hair growth promoters can be broadly classified into those using (1) animals, (2) humans and (3) tissue cultures. In (1) the growth of the animals' hair is investigated by monitoring the hair weight, hair length and area of hair growth and recording the time at which hair started to grow. However, it is necessary to take the species, age, season, feed and so forth into consideration when monitoring hair growth in animals. In the final evaluation of the effectiveness of a hair growth promoters, they must be tested on humans. In the testing on humans there are many problems which have to be solved; for example, individual differences, variations between different locations the difficulty of controlling the people undergoing the tests and the poor understanding of daily and seasonal fluctuations. Despite this, tests like those listed under (2) in Table 3.2 are actually carried out. Although it is difficult to obtain data for the photographic evaluation and observation of hair growth situation (2a), both objectively and quantitatively, the tests can be carried out on large numbers of people. In the case of (2b-e), however, quantitative data can be obtained more easily but the costs are high and subject management requires a lot of effort.

Hair care cosmetics

All

Table 3.2. Methods of evaluating hair growth promoters ®

Evaluation using animals^^'^^' Mice a , Measure hair length b . Measure area of hair growth Rabbits a . Measure hair length and weight b . Record start of hair growth Hamsters a . Measure size of sebaceous glands {in vivo) b . Measure inhibition of 5<3'-reductase {in vitro) c . Measure inhibition of DHT receptor {in vitro) Monkeys a . Measure hair growth at front of head (red-faced monkey)

®

Evaluation using humans a . Photographic evaluation, observe hair growth situation b . Trichogram method c . Measure inhibition of 5<ar-reductase (hair root) d . Hair-wash test e . Measure blood flow

(3) Evaluation using tissue cultures a . Culture hair roots b . Culture hair root cells

Using the trichogram method^^^ (2b), the proportion of hairs in the telogen phase is determined in order to assess how effectively the growth of the hair is being promoted. This is done by taking a random sample of about 100 hairs from different parts of the head and categorizing them as anagen, catagen or telogen by examining the state of their hair follicles under a microscope. In (2c), the 5a-reductase activity in human hair follicles is measured before and after using a hair growth promoter, in order to determine the inhibition of Sa-reductase in the hair root. In the hair-wash test in (2d), the number of hairs coming out on washing is measured. In this, it is very important for the persons taking part in the test to strictly control their hair washing routine in order to obtain persuasive data. In (2e), the rate of blood flow is measured as an evaluation of a hair growth promoter because it is considered that improving the circulation in the scalp will promote hair growth. Devices employing the doppler effect and those using thermocouples are some of the equipment which have been developed for doing this. When using them, it is necessary to make the measurements in consideration of the conditions under which the measurements are to be made. Concerning the tissue culture methods in (3), Wetterings et al^^^ have reported success in culturing hair follicle keratinocytes on the membrane covering the crystalline lens of the cow eye. Jahoda and Oliver^^) have looked into the culturing of dermal papilla cells, which are also considered to be very important to hair growth. The culturing of hair follicles and hair follicle tissue cells is another way of evaluating hair growth promoters and it is also considered to be an excellent evaluation tool for clarifying the mechanism of hair growth. As there are so many causes for hair loss, many different ingredients go into the formulae for hair growth promoters. The following is an example of one.

418 New cosmetic science Typical formula. Hair growth promoter Ethyl alcohol Hinokitiol Swertia extract Vitamin 65 Vitamin E derivative Propylene glycol Perfume Perfume solubilizer Purified water

% 60.0 q.s. q.s. q.s. q.s. 2.0 q.s. q.s. 38.0

Manufacturing procedure Make a solution by adding all of the ingredients except the purified water to the ethyl alcohol in the above order. Then add the purified water, solubilize, make into a uniform solution and filter.

3.3. Hair grooming cosmetics This type of cosmetic product is used every day, particularly after washing the hair, to add the finishing touches to hair care. In Japan, hair cleansing cosmetics are referred to as "cosmetics used in the bathroom" and hair styling cosmetics as "cosmetics used outside the bathroom" because the place where the bath and shower are is separate from the place where personal styling is carried out. Functionally speaking, they are divided into two types, one mainly for setting and adjusting the hairstyle and the other, known as the hair treatment type, for enhancing the hair's gloss and feeling to the touch, giving it a nice quality and making it easier to manage. There are also combinations of these two types. In this section, hair styling cosmetics will be divide into two groups for the purpose of discussing them: hair styling preparations for adjusting the hairstyle; and hair treatment preparations which incorporate both treatment and styling functions. 3.3.1. Types of hair styling preparation Preparations for setting the hair comprise those which are solid at normal temperatures, pastes or those employing viscous liquid oils and fats, types employing polymer resins and types employing viscous humectants. In terms of physics, the hair is styled through the preparation's close adhesion to the hair and setting qualities. Types employing oils and fats and humectants make use of the viscosity of these substances to do this while the type employing polymer resins utilizes their stiffening ability. We will now describe the different types of product for each type of preparation. 3.3.1.1. Hair foam, hair mousse® Hair foam is the general name for foaming hairstyling preparations which consist of a styling concentrate and a propellant (liquefied gas) in a metal aerosol can. When

Hair care cosmetics 419

the styling concentrate is sprayed out of the can, the liquefied gas in it vaporizes under atmospheric pressure increasing the volume of the styling concentrate by making it into a foam. The features of such preparations are that there are virtually no viscosity restrictions on the styling concentrate and as the product is shaken before use, there is a high degree of freedom in the form of the styling concentrate to permit any separation to be reversed. As this makes it easy to develop new functions, there are many types of product. They can be broadly divided into types with setting ability as their main feature, types focusing on hair treatment and types which produce a wet gloss. Setting preparations (refer to Section 3.1.4 in Part II) incorporate such ingredients as oils (liquid paraffin, silicones), humectants and activators, and formulae for them are drawn up in consideration of the application. In recent years, many highly specific products for different hairstyles, different hair types, different final appearance and for covering split ends have come on to the market. Typical formula 1. Hair foam (hard set type) StyHng concentrate formula

Filling formula

Acrylic resin alkanolamine solution (50%) Polyoxyethylene-hydrogenated castor oil Liquid paraffin Glycerin Perfume, preservative Purified water Ethyl alcohol Styling concentrate Liquefied petroleum gas (LPG)

% 8.0 q.s. 5.0 3.0 q.s. 69.0 15.0 90.0 10.0

Manufacturing procedure Add the liquid paraffin to a solution of the glycerin and the polyoxyethylenehydrogenated castor oil, and make into a uniform emulsion in a Homomixer. Add this to a solution of the other ingredients. Fill cans with the styling concentrate, attach the valves and add the gas. Typical formula 2. Hair foam (treatment type) Styling concentrate formula

Filling formula

Cationic cellulose Polyoxyethylene-hydrogenated castor oil Silicone oil Dipropylene glycol Ethyl alcohol Perfume, preservative Purified water Styling concentrate LPG

7o

3.0 q.s. 5.0 7.0 15.0 q.s. 70.0 90.0 10.0

Manufacturing procedure Add the silicone oil to a solution of the dipropylene glycol and the polyoxyethylenehydrogenated castor oil, and make into a uniform emulsion in a Homomixer. Add this to

420 New cosmetic science

a solution of the other ingredients. Fill cans with the styling concentrate, attach the valves and add the gas. 3.3.1.2. Hair spray, hair mist Hair spray and hair mist are sprayed on to hair which has been set to keep the style in place. Here, we will define hair sprays as products in aerosol cans and hair mists as products in dispensers. However, there are also products with these names that do not fit our definitions. The main ingredients of hair sprays are film forming agents. They also contain higher alcohols, lanolin derivatives and other ingredients to give the film an appropriate degree of plasticity. Such ingredients as silicones are used to give a gloss. Film forming agents used include polyvinyl-pyrrolidone, copolymers of it with vinyl acetate, acrylic resin alkanol amine solution and butyl esters of PVM/MA copolymer. Formerly, ethyl alcohol was the solvent used in almost all cases but nowadays purified water is also used. This is because of the need to reduce the flammability of the flammable propellants which came into use with the enactment of the Montreal Protocol in 1989, to restrict the use of chlorofluorocarbons, and the Volatile Organic Compounds (VOC) Regulations enacted in 1993 in America, which set the maximum VOC content for hair spray at 80% for 1993 and 55% for 1998. LPG and mixtures of LPG and dimethyl ether are now used as propellants. In the selection and formulation of propellants, it is necessary to carry out thorough quality inspections on such aspects as resin solubility, pressure, state of the spray and can corrosion. Typical formula. Hair spray Concentrate formula

Filling formula

Acrylic resin alkanolamine solution (50%) Cetyl alcohol Silicone oil Ethyl alcohol Perfume Concentrate Dimethyl ether

7.0 0.1 0.3 92.6 q.s. 50.0 50.0

Manufacturing procedure To make the concentrate, dissolve all of the ingredients in the ethyl alcohol and filter. The filling process is the same as for hair foam. Hair mist comprises film forming agents dissolved in ethyl alcohol and its formula is similar to that for hair spray. As they should dry very quickly, few mists contain water. 3.3.1.3. Hair gel, water grease Hair gel and water grease are jelly-form transparent preparations which contain styling ingredients and are thickened using water soluble polymers. The styling ingredients added are resins and they produce a dry effect. The ingredients for hair gel include water soluble polymers (carboxyvinyl polymer, methylcellulose, carrageenan, etc.), setting agents (polyvinyl pyrrolidone, polyvinyl pyr-

Hair care cosmetics 421

rolidone/vinyl polymer acetate, etc.), humectants, alkalizing agents, surfactants and chelating agents. Water grease, which is also called water pomade, has a different type of formula from the "hair solid" of the 1970s which was called water soluble pomade. Hair solid was made soluble in water by gelling its oils using surfactants, whereas for water grease, the wet feeling after application is obtained by adding such humectants as glycerin to a thickening system created from water soluble polymers. The major ingredients of water grease are water soluble polymers (same as for gels), humectants (glycerin, 1,3 butylene glycol, etc.), setting agents, alkalizing agents, surfactants and chelating agents. Typical formula 1. Hair gel Carboxyvinylpolymer Polyvinylpyrrolidone Glycerin Sodium hydroxide Ethyl alcohol Polyoxyethyleneoctyldodecyl ether Perfume, chelating agent Purified water

% 0.7 2.0 q.s. q.s. 20.0 q.s. q.s. 77.3

Manufacturing procedure Make a dispersion of the carboxyvinylpolymer in the glycerin and some of the purified water; then dissolve the rest of the ingredients in the remaining purified water and add this while stirring. Typical formula 2. Water grease Carboxyvinylpolymer Glycerin Sodium hydroxide Ethyl alcohol Polyoxyethyleneoctyldodecyl ether Perfume, chelating agent Purified water

% 0.5 50.0 q.s. 10.0 q.s. q.s. 35.0

Manufacturing procedure Same as for hair gel. 3.3.1.4. Setting lotion^ curler lotion Set lotion and curler lotion, which are made by dissolving gums and resins in a solution of ethyl alcohol and purified water, are applied to a brush or curlers to style the hair. Initially natural gums (tragacanth gum and karaya gum) were used as setting agents but nowadays synthetic polymers are used because they show little variation in quality. The synthetic polymers listed below are examples of the many that have been developed.

422 New cosmetic science (1)

Nonionic polymers: polyvinylpyrrolidone, polyvinyl-pyrrolidone/vinyl acetate copolymer. (2) Anionic polymers: aery late ester/methacrylate ester copolymer, vinylmethyl ether/butyl maleate copolymer. (3) Cationic polymers: cationic vinyIpyrrolidone/dimethylamino-ethyImethacrylate copolymer. (4) Amphoteric polymers: hydroxypropyl acrylate/butylaminoethyl methacrylate/octylamide acrylate copolymer. In the selection of resins, attention must be paid to setting ability, characteristics of the film formed and tendency to clog dispensers. As there is a tendency for films formed by resins alone to peel off and it look as though a white powder had been blown over the area, humectants (glycerin, 1,3-butylene glycol) and plasticizers (synthetic esters, silicone derivatives) are added as well. However, this must be done with consideration for the setting ability. Typical formula. Setting lotion Poly viny Ipyrrolidone/vinyl acetate copolymer Preservative Perfume Ethyl alcohol Purified water Silicone derivative Glycerin

% 5.0 q.s. q.s. 30.0 62.5 0.5 2.0

Manufacturing procedure Make a solution from the purified water, silicone derivative and glycerin (water phase); then make a uniform solution of the copolymer, preservative and perfume in the ethyl alcohol and add the water phase. 3.3.1.5. Hair liquid Hair liquid is an aqueous solution formed by dissolving styling ingredients in ethyl alcohol. It's features are that it has a softer styling effect than pomade or hair stick, has a more refreshing feeling after application and is easier to wash out than hair oil. Polyalkylene glycol is the main styling agent used. The addition of propylene glycol in varying mole numbers enables the viscosity and solubility in alcohol of compounds to be adjusted. The development of polyalkylene glycol, has enabled hair liquid to be improved greatly in the functional sense. It no longer damages spectacle frames or the celluloid of combs, it is easily removed when it gets on to clothes and has very little stickiness. Typical formula. Hair liquid Polyoxypropylene(40)butyl ether Polyoxyethylene-hydrogenated castor oil Ethyl alcohol Purified water

% 20.0 1.0 50.0 28.0

Hair care cosmetics 423 Perfume Dye Preservative, ultraviolet absorbent

1.0 q.s. q.s.

Manufacturing procedure Make a solution of the polyoxypropylene(40)butyl ether, polyoxyethylene-hydrogenated castor oil, fragrance, preservative and ultraviolet screen in the ethyl alcohol (alcohol phase). Dissolve the dye in the purified water (water phase). Add the water phase to the alcohol phase and filter using filter paper or other means. 3.3.1.6. Pomade, hair stick Pomade, a jelly-form or slightly hard semi-solid oil preparation, is used to give a gloss to the hair as well as for styling purposes. Hair stick is a stick-form solid hairstyling preparation used specially for styling stiff hair. There are plant oil and mineral oil based pomades. The main ingredients of the former are castor oil and Japan wax, while the main ingredient of the latter is petrolatum. Plant oil based pomades are semitransparent preparations with a luster and an appropriate hardness and viscosity which are very popular among Japanese because they have stiff hair. Mineral oil base pomades are non-sticky hairstyling preparations which give a refreshing feeling. As the mineral oil used to make them has no smell, it is easy to add a perfume. They are thus used to make the hair smell nice. A difference between hair stick and pomade is that many solid oils and fats are used to increase the hardness. There are hair sticks to which an appropriate amount of carbon black has been added to make gray hairs less obvious. Typical formula 1. Pomade (plant oil based) Castor oil Purified Japan wax Perfume Dye Antioxidant

% 88.0 10.0 2.0 q.s. q.s.

Manufacturing procedure Mix the castor oil, purified Japan wax and antioxidant together and heat to dissolve. Add the perfume and dye to this and pour into a metal vat, etc.. Gently, rapidly cool using ice to solidify. Typical formula 2. Hair stick Polyoxyethylene(40)butyl ether Bleached beeswax Refined Japan wax Glyceryl monostearate, self-emulsifying Glyceryl monostearate, lipophilic Perfume

% 70.0 10.0 4.0 7.0 4.0 q.s.

424 New cosmetic science Manufacturing procedure Make a solution of all of the ingredients apart from the perfume by heating (80°C). Add the perfume to this, pour into molds and cool rapidly. 3,3.2. Types of hair treatment preparation^^^^^^ The following is a description of some of the hair treatment preparations available. 3.3.2.1. Hair cream Hair cream is an emulsion product which gives the hair a gloss, flexibility, a moist feeling and makes it easier to comb. It can also have an appropriate amount of hair styling capability depending on the requirements. If a lot of oil is put on the hair, this tends to make it feel sticky to the hands. Hair cream does not, however, as it is an emulsion. It feels quite refreshing on use, the oils in it have a conditioning effect and it also has a humectant function. The main ingredients of hair cream are liquid oily ingredients. It also has an aqueous component of 30-70%. The emulsion is either an 0/W or a W/0 type. In general, the former has very little stickiness and is very refreshing and the latter has a certain oiliness, produces an excellent gloss and is very good for styling. Either one is selected depending on the requirements. Some of the ingredients used in the formulae for hair creams are oils and fats (olive oil, camellia oil, triglycerides), hydrocarbons (liquid paraffin, petrolatum, ceresin, microcrystalline wax), waxes (beeswax, lanolin), higher fatty acids (lauric acid, myristic acid), higher fatty acid esters (isopropyl myristate, butyl stearate), higher alcohols (cetanol, stearyl alcohol), silicones, surfactants, humectants (propylene glycol, glycerin, thickening agents (carboxyvinyl polymer, xanthan gum), organic amines, inorganic alkalis, preservatives and chelating agents. Great care has to be taken when making up formulae, however, because there are changes in utility, function and stability when they are used in combination with other ingredients. Typical formula. Hair cream (O/W type, milky lotion type) (1)

(2)

(3)

Liquid paraffin Petrolatum Bleached beeswax Preservative Perfume Purified water Carboxyvinyl polymer Xanthan gum Glycerin Polyoxyethylene-hydrogenated castor oil Chelating agent Color Sodium hydroxide

%

15.0 15.0 2.0 q.s. q.s. 59.75 0.1 0.1 5.0 3.0 q.s. q.s. 0.05

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425

Manufacturing procedure Heat the ingredients in (1) to solubilize and keep at 80°C; then heat the ingredients in (2) to solubilize and keep at 80°C. While stirring, add (1) to (2) and emulsify using a Homomixer. Cool to 30°C, add (3) and stir until uniform. 3.3.2.2. Hair blow Hair blow is a preparation which is sprayed out of its dispenser by pump action. It has conditioning and styling effects. The type in which the conditioning effect is stressed is called treatment lotion or blow lotion. The purpose of this product is to protect the hair from heat when blow-drying it and friction when brushing it. The types of hair blow range from those whose oils and humectants simply adhere to and are adsorbed on to the surface to the hair and scalp by physical processes, to those which, like rinses, contain cationic surfactants to effect ionic bonding on the surface of the hair and scalp in order to change their electrostatic state to improve the quality of the hair. Some of the ingredients of hair blow are cationic agents, ethanol, silicone derivatives, humectants, oils, hydrolyzed protein and preservatives. Typical formula. Treatment lotion (1)

(2)

1,3-butylene glycol Glycerin Stearyltrimethylammonium chloride Methylphenyl polysiloxane Collagen hydrolysate Perfume, preservative, ultraviolet absorbent: Ethanol Purified water

%

2.0 1.0 0.5 1.0 1.0 q.s. 50.0 44.5

Manufacturing procedure Stir the ingredients in (2) together to solubilize and make a solution of this and the ingredients in (1). In some products, the treatment effect is enhanced by adding emulsified oils (liquid paraffin, silicones). 3.3.2.3. Hair coating lotion for split ends Hair coating lotion for split ends was developed in Japan in response to the need for a cosmetic which would repair and prevent split ends, the bane of Japanese women when long hair was in fashion around 1988. This type of product was also marketed in the US and Europe where it was very well received. The main ingredients are polymer silicone (dimethyl polysiloxane) and volatile oils (low boiling point isoparaffins, etc.). In the formulation, the polymer silicone is used to the utmost to achieve the greatest coating effect, smoothness, adherence and water resistance. Typical formula. Hair coating lotion for split end Dimethyl polysiloxane

% 10.0

426 New cosmetic science Silicone oil Light isoparaffin Perfume

20.0 70.0 q.s.

Manufacturing procedure Make a solution of all of the ingredients at room temperature. 3J.2A. Hair oil Hair oil is used to supplement the hair's oil, give it a gloss, smoothness and flexibility. In Japan, plant oils have been used exclusively for hair oil and in this respect, camellia oil has been in use since long ago. The main ingredients are plant oils with relatively low viscosities (camellia oil, olive oil) and mineral oils (liquid paraffins). Some of the other ingredients are higher fatty acid esters, squalane and silicones. However, especially in the case of unsaturated plant oils, it is necessary to add a suitable antioxidant because they may become rancid after some time and produce an unpleasant smell. Hair oil has been used as a pomade since long ago but there is a tendency for it to be used less these days because of its oiliness. Typical formula. Hair oil Liquid paraffin Olive oil Perfume Antioxidant

% 80.0 19.0 1.0 q.s.

Manufacturing procedure Make a solution of all of the ingredients at room temperature.

3.4. Permanent waving lotion 3A,L

History

There are records showing that putting waves in the hair to adorn oneself was already being practiced in 3000 BC in ancient Egypt. This was done by winding the hair around a stick, putting clay on this and letting it dry in the sun. In Greek and Roman times, waves were put in the hair using a heated iron rod and virtually the same method was used until the 19th century. However, this type of wave cannot be called permanent because it soon came out. The first success in making a permanent wave was achieved by Nestler, a German, in 1905. He did this by using an alkaline aqueous solution of something like borax to treat the hair chemically and heated it electrically. In the years afterwards, Nestler's heating apparatus was improved and ammonia or ammonium carbonate were used instead of borax and in the 1920s the "electric perm" was all the rage. In 1923, Sartory replaced the heat from electricity with that from a chemical reaction. This method used the heat of hydration of lime and soon enjoyed widespread use as the

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427

"machineless wave". It also provide the impetus for the development of permanent waving solutions. In 1934, Goddard and Michelis used thioglycolic acid salts and through the use of sodium hydrogen sulfite by Speakmann in 1936, the temperature at which a good wave could be obtained was lowered from around 100°C, which had been necessary for waving until that time, to about room temperature. As a result, permanent waving came to be known as the "cold perm". Then, the American, McDonough, started research on cold permanent waving lotions using thioglycolic acid as their main ingredient in the early 1940s which resulted in the development of a product similar to the one in use today. 3.4.2. Permanent waving

mechanism

Hair has a mesh-like structure^^^ which is formed by various types of side-chain bonding of the polypeptide chains in keratin, its principal component (refer to Chapter 2 in Part I). Of these various types of side-chain bonding, the most important to permanent waving is the disulfide bond (S-S bond) because it is the strongest. Disulfide bonds are broken by a reducing agent forming cysteine but new disulfide bonds can be made using an oxidizing agent. Reducingagent

Keratin-S-S-Keratin
(a) Untreated hair

(b) After treatment with (c) After treatment with agent No. 1 (reducing agent No. 2 (oxidizing agent) agent)

Fig. 3.1. Process of forming permanent waves.

428 New cosmetic science

What happens is, as a result of the disulfide bonds being broken in the reduction reaction, the non-crystalline zone around the crystalline zone becomes more pliable and its microfibrillar structure is rearranged to take on the form of the curler. In these circumstances, oxidation fixes the microfibrillar structure in the new form of the wave. 3A.3.

Types of permanent waving lotion

The permanent waving lotions that are permitted to be manufactured and sold in Japan, and imported, are only those which conform to the Ministry of Health and Welfare's "Standards for Permanent Waving Lotions". These permanent waving lotions are classified on the basis of their usage and ingredients. Regarding usage, products are classified into those which are used at normal temperatures and those which require the temperature to be raised, products consisting of only one waving agent and those consisting of No. 1 and 2 waving agents, those which require mixing to produce heat and those which do not, and those whose purpose is waving and those which straighten out natural curls. At present, the majority of permanent waving lotion products are those consisting of 2 waving agents (No. 1 and No. 2). The No. 1 waving agent (generally called waving lotion) is the one which breaks the disulfide bonds in the first process of wave formation in Fig. 3.1b. Its main ingredient is a reducing agent. The No. 2 waving agent (generally called neutralizer) is the one which forms new disulfide bonds in the second process of wave formation in Fig. 3.1c. Its main ingredient is a oxidizing agent. The reducing agents used in the No. 1 waving agent can be broadly divided into those using thioglycolates and cysteines as their main ingredients. In the US and Europe, glycerylmonothioglycolate is also used as a reducing agent. Waving lotions using this reducing agent are generally called "acid perm", whereas those using thioglycolates and cysteines are generally called "alkaline perm". 3.4.3.1. Permanent waving lotions having thioglycolates as their main ingredient Thioglycolic acid and its salts (ammonium salts, monoethanol amine salts, sodium salts, etc.) are used as reducing agents in permanent waving lotions. Some of the other ingredients are alkalizing agents, surfactants and stabilizers). The strength of the wave can be adjusted through the quantity of the thioglycolic salt and the alkalizing agent. Care must be taken, however, to ensure the purity of the water and raw materials used because the lotion will become colored, spoiling the appearance of the wave, and reducing capability will be impaired as a result of reactions between copper, iron and other metallic ions and thioglycolic acid salts. Ammonia, amines, ammonium salts and basic amino acids are used as the alkalizing agent. Among them, ammonia is much used because it has an appropriate swelling action on the hair, leaves no residue because it is volatile and it is very safe. Owing to its lack of smell, monoethanolamine is also widely used for this purpose but care must be taken with the amount in the formula and when rinsing with water during the waving process because of the possibility of it staying behind in the hair due to its lack of volatility. This type of permanent waving lotion also contains edetic acid salts and other types of

Hair care cosmetics 429 chelating agent as a stabilizer, nonionic surfactants to aid the permeation and emulsification of the active ingredients, and cationic surfactants and oils to raise utility. Typical formula. No. 1 waving agent (waving lotion) Ammonium thioglycolate (50% aqueous solution) Aqueous ammonia (28%) Stearyltrimethyl ammonium chloride Propylene glycol Ion exchange water Edeto acid salt Perfume

% 10.0 3.0 0.1 5.0 81.9 q.s. q.s.

Manufacturing procedure Make a uniform mixture by stirring all of the ingredients together, adding the ammonium thioglycolate and aqueous ammonia last. 3.4.3.2. Permanent waving lotions having cysteine as their main ingredient Cysteine is also used as a reducing agent. Compared to thioglycolic acid, it has little irritating smell and it is much more difficult for it to damage the hair but the problem is that it does not form strong waves. The ingredients are primarily the same, except for cysteine, as in Section 3.4.3.1. in Part II, but it is good to add ammonium thioglycolate as well. On reducing the hair cystine bonds, cysteine is oxidized to cystine which crystallizes to form an insoluble white powder. This powder gets on to the hands and hair and cannot be removed by rinsing alone. Adding ammonium thioglycolate prevents the crystallization of cystine. Typical formula 1. No. 1 waving agent (waving lotion) Cysteine Ammonium thioglycolate Monoethanolamine Ion exchange water Edeto acid salt Perfume

% 5.0 0.3 2.0 92.7 q.s. q.s.

Manufacturing procedure Make a uniform mixture by stirring all of the ingredients together. 3.4.3.3. Permanent waving lotions having glycerylmonothioglycolate as their main ingredient Glycerylmonothioglycolate is another reducing agent used in permanent waving lotions. As this reducing agent is hydrolyzed by water, the waving lotion consists of two parts, part A and part B. Part A contains the glycerylmonothioglycolate and part B the other ingredients (alkalizing agent, perfume, surfactants, etc.). Immediately before use, both parts are mixed together. It is arranged that the alkalizing agent in part B makes the pH of the mixture slightly acidic to neutral.

430 New cosmetic science Ps.s it is possible for this type of waving lotion to irritate the skin, beauticians often wear gloves or use the water wrap method when using it for perming. Waving lotions containing glycerylmonothioglycolate produce a softer wave than thioglycolate containing alkaline perms but damage the hair less. Although they are a widely used type of alkaline perm in the US and Europe, they are not used in Japan. Typical formula. No. 1 waving agent (waving lotion) Part A Part B

Glycerylmonothioglycolate (60%) Aqueous ammonia (28%) Ion exchange water Perfume Surfactant

% 30.0 q.s. 70.0 q.s. q.s.

Manufacturing procedure Stir all of the ingredients together to make a uniform mixture. There are two types of No. 2 waving agent (neutralizer), those having potassium bromate, sodium bromate or sodium perborate as their main ingredient, and those having aqueous hydrogen peroxide as their main ingredient. The No. 2 waving agent also includes a pH buffer in its formula so that the oxidation may take place under a constant pH. In addition, for the same reason as for the No. 1 agent, surfactants and oils are included in appropriate amounts. Typical formula. No. 2 waving agent (neutralizer) Sodium bromate Silicone emulsion Ionic exchange water pH buffer

% 5.0 1.0 94.0 q.s.

Manufacturing procedure Stir all of the ingredients together to make a uniform mixture.

3.5. Hair color, hair bleach The following are two possible motives for coloring the hair: (1) to give a younger appearance by making gray hairs less prominent (2) to be more stylish by actively varying the color of the hair. The aim of the former is to hide gray hair by coloring it and the latter to look more chic by changing the color of the hair: there are many types of hair color product for both. In this section, we discuss both hair color and hair bleach which are used for opposite purposes. 3.5.7. History^^) In 3000 BC in ancient Egypt, natural substances of plant or mineral origin were used to

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431

dye the hair. The oxidation hair colors which are widely used today were developed in the latter half of the 19th century with the discovery of paraphenylenediamine. In Japan, "shiragazome" (dyeing gray hair black using tannic acid and iron salts) was practiced until the end of the 19th century. After that, hair coloring agents employing paraphenylenediamine began to be used in Japan. 3.5.2. Classifications of hair color and their mechanisms Hair colors are classified on the basis of their degree of durability, i.e. how long their dyeing effect lasts, into temporary hair colors, semi-permanent hair colors and permanent hair colors, and the mechanism by which they color the hair is different for each. Fig. 3.2 shows diagrammatically the physical and chemical processes involved in dyeing, for different parts of a single hair^^^ The action of the color begins when it comes into contact with the outermost layer of the hair, i.e. the epicuticle (outermost layer of the cuticle). Here we can observe the interface phenomena of wetting and adsorption at the liquid-solid interface. The hair color then passes through the cell membrane complex and through the cuticle into the cortex by permeation and diffusion. A polymerization reaction may also take place. The mechanism by which different parts of a single hair are colored can be generally explained as shown in Fig. 3.3. 3.5.2.1. Epicuticle surface Hair is dyed when a pigment or dye becomes fixed on the surface of the epicuticle. This may be facilitated by different methods such as cohesion by means of oils and fats (color stick), cohesion by means of water soluble polymer gels (color gel) and adhesion by means of polymer resins (color spray, color mousse). There are some gel products which contain hair color but not enough to cover the en-

(Concentration gradient)

Fig. 3.2. Action of hair color on the hair.

432 New cosmetic science Color Cuticle

Medulla

Cortex (1) Outermost layer of cuticle (epicuticle) (Temporary hair color)

(2) Parts of cuticle and cortex (Semi-permanent hair color)

(3) Cortex (Permanent hair color)

Fig. 3.3. Mechanisms by which different hair colors act.

tire cuticle. In this case, it is the gel base itself which coats the hair and as a result of the effect, light gray hair appears less prominent. This mechanism covers products classified as temporary hair colors. 3.5.2.2. Parts of cuticle and cortex In this case, acidic dyes permeate into parts of the cuticle and cortex and the color is taken up by the hair by means of ionic bonding. The permeation of dyes with large molecular weights is facilitated using the carrier effect of such solvents as benzyl alcohol. This mechanism covers products classified as semi-permanent hair colors whose color lasts for about 1 month. 3.5.2.3. Cortex In this case, monomer oxidation dyes (amine and phenol compounds) permeate into the hair and an oxidizing agent (usually aqueous hydrogen peroxide) is used to effect oxidizing polymerization to form a polymer color which is taken up by the cortex. Owing to its polymer nature, the color formed inside the cortex is permanently fixed in the hair. This mechanism covers products known as permanent hair colors. 3.5.3. Types of hair color 3.5.3.1. Temporary hair color Temporary hair color comes in such forms as sticks, gels, sprays and mousses. Though their color does not last for very long, such products are easy to wash out with shampoo, are simple to use and highly safe. The main coloring agents used in them are carbon black and pigments but acid dyes may also be used. (1) Color stick. A stick-form temporary hair color used to color gray hair in the sidelocks and other parts of the hair. Typical formula. Color stick Carbon black Beeswax

% 2.0 15.0

Hair care cosmetics 433 Japan wax Castor oil POE(20)sesquioleate Perfume Antioxidant

10.0 66.8 1.2 5.0 q.s.

Manufacturing procedure Melt the oily ingredients and make into a uniform mixture, mix in the carbon black and cool. (2) Color spray. An aerosol hair color used to give a cheerful, fashion color to the hair and color gray parts. Typical formula.

Co lor spray

Hair color solution

Fining formula

Pigment Acrylic resin alkanolamine solution (50%) Ethyl alcohol Perfume Hair color solution LPG

% 1.0 6.0 93.0 q.s. 70.0 30.0

Manufacturing procedure Make a uniform mixture of the hair color solution ingredients and then put into aerosol cans. (3) Liquid type. A hair color in a bottle used to color different parts of the hair with its attached brush Typical formula. Liquid type Pigment Acrylic resin alkanolamine solution (50%) Ethyl alcohol Perfume

% 1.0 8.0 91.0 q.s.

Manufacturing procedure Make a uniform mixture of all of the ingredients. 3.5.3.2. Semipermanent hair colors Semipermanent hair colors come as liquids, gels and creams. They all mainly employ azo acid dyes and also contain such solvents as benzyl alcohol and A^-methyl pyrrolidone^"^). As a very strong dyeing effect is achieved under acidic conditions, an acid like citric acid is usually added to regulate the pH. Such hair colors are usually designed so that they dye the hair completely in one application. However, as there are people who do not like the difference between before and after using a hair color to be too great, under this product classification, there are

434 New cosmetic science

also "color rinses" in which the coloring effect has been regulated so that the hair is colored gradually through several applications. It is important to achieve a good balance between the strength of the coloring effect on the hair, and the residue left on the scalp and hands. (1) Gel type. In this product, the hair color has been made into a gel through the use of a thickening agent to prevent it from dripping off during use. Examples of thickening agents used are carboxymethyl cellulose and xanthan gum. It is used to color all of the hair or just parts of it. Typical formula. Gel type Acidic dye Benzyl alcohol Isopropyl alcohol Citric acid Xanthan gum Purified water

% 1.0 6.0 20.0 0.3 1.0 71.7

Manufacturing procedure Make a dispersion of the xanthan gum in the benzyl alcohol and add this to a mixture of the other ingredients. 3.5.3.3. Permanent hair color^^^^^^ Permanent hair color has this name because its coloring effect is more permanent than that of temporary hair color and semipermanent hair color. Under this type, there are oxidation hair colors, plant-based hair colors and metallic hair colors. (1) Oxidation hair colors. They are the most used among hair colors because they are more permanent and, as a result of their bleaching effect, it is possible to obtain a lighter color than the original hair color (especially good when dyeing black hair a fashionable color). They come as powders, liquids and creams. The liquid and cream types are the main ones at present. As mentioned previously, the mechanism of permanent hair colors involves the formation of an oxidation polymer from an oxidation dye through the use of an oxidizing agent, so this product consists of 2 bottles (one in the case of the powder type as the oxidation is carried out by the air): one containing the hair colorant, which incorporates oxidation dyes; and the other the color developer, which incorporates the oxidizing agent. When used, the hair colorant and color developer are mixed together. In addition to the oxidation dye, the hair colorant also contains such ingredients as alkalizing agents and surfactants. Oxidation dyes comprise dye precursors (ortho and para type phenylenediamines, aminophenols and their derivatives) which color through selfoxidation, and couplers (meta type phenylenediamines, aminophenol and polyvalent phenols) which result from the combination of different dye precursors and produce many different color shades. Alkalizing agents are included in formulae to enhance the dyeing effect and produce lighter colors by promoting the oxidative degradation of

Hair care cosmetics 435

f ^ ^ ^ "

Oxidation

P-phenylenediamine

1^^^^"

fy^^

Di-imine

X, Y = 0 or NH R-H, Me, MeO

•Ni,

Oxidation

P-phenylenediamine

Indo dye Fig. 3.4. Oxidation in hair coloring (J. F. Corbett: Cosmetics and Toiletries, 91,21 (1976)). melanin granules in the hair. However, as alkalis have such a damaging effect on the hair, there are now many hair colors on the market which are designed so that the reactions take place under neutral to weakly acidic conditions^^^. Hydrogen peroxide is the main oxidizing agent used in the color developer. As it decomposes so easily, chelating agents and pH adjusters and other stabilizing agents are added. The oxidation reaction takes place as shown in Fig. 3.4^^^. In the initial reaction in the hair, the dye precursor (paraphenylenediamine in Fig. 3.4.) is oxidized to di-imines by hydrogen peroxide^^'^^^ The di-imines then react with couplers or other precursors to form indo dyes. Through different combinations of dye precursors and couplers, and varying the degree of polymerization, different color shades may be obtained (Fig. 3.5). Typical formula 1. Liquid type (hair colorant) P-phenylene diamine Resorcinol Oleic acid Polyoxyethylene(10)oleyl alcohol ether Isopropyl alcohol Aqueous ammonia (28%) Purified water Antioxidant, chelating agent

% 3.0 0.5 20.0 15.0 10.0 10.0 41.5 q.s.

Manufacturing procedure Make a uniform mixture of all the ingredients. To prevent the oxidation dyes from being oxidized by the air, they should be added last.

436 New cosmetic science Brown, red-purples

Brown, greens

m-aminophenol NH2

NH,

NH Oxidation f^^^^X NH

NH2

P-diamine

•

H2N NH2

Bandrowski's base (browns) m-diamine

Blue, blue-purples

Purple, blue-purples Fig. 3.5. Color shades of oxidation dyes.

Typical formula 2. Liquid type (color developer) Aqueous hydrogen peroxide (30%) Purified water Stabilizer

7o

20.0 80.0 q.s.

Manufacturing procedure Make a uniform mixture of all the ingredients. Very rarely, there may be people who are allergic to oxidation dyes so it is essential to carry out a patch test before use^i\ (2) Other permanent hair colors. There are plant-based hair colors such as those using henna leaves (active ingredient 2-hydroxy-l,4-naphthoquinone) and chamomile flowers (active ingredient 4',5,7-trihydroxyflavone) as their raw materials. There are also a and ^ unsaturated compounds which cause 1,4-addition reactions with hair protein free amino groups and other nucleophilic residual groups'^^^ Regarding mineral-based hair colors, there are those employing oxides of such metals as lead, iron, bismuth, nickel and cobalt. 3.5.4, Hair bleach Hair bleach bleaches the hair by oxidizing the melanin in it. Many hair bleaches comprise two bottles whose contents are mixed together on use. One bottle is the alkaline solution which contains an alkalizing agent and the other is the color developer which contains aqueous hydrogen peroxide. There are also strong bleaches some of which have boosters (ammonium and other persulfates) added to them and others in which soda pyrosulfite is added to the alkaline solution, and the heat from the oxidation-reduction reaction is used in the bleaching process.

Hair care cosmetics 431 Typical formula 1. Alkaline

solution

Polyoxyethylene(10)nonylphenyl ether Polyoxyethylene(15)distearate Palmitic acid Aqueous ammonia Chelating agent Purified water

% 20.0 10.0 4.0 9.0 q.s. 57.0

Manufacturing procedure Heat the purified water and add all of the ingredients, apart from the ammonia, to make a solution; then cool and add the ammonia. Typical formula 2. Color developer Polyoxyethylene(4)nonylphenyl ether Polyoxyethylene(9)nonylphenyl ether Cetyl alcohol Aqueous hydrogen peroxide (35%) Stabilizer Purified water

% 5.0 5.0 52.0 17.0 q.s. 21.0

Manufacturing procedure Dissolve the stabilizer in the purified water; then heat and dissolve the other ingredients in this. Cool while stirring.

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

Miyazawa, K., Tamura, U., Uchikawa, K., Sakamoto, T., Tomita, K.: J. Jpn. Oil Chem. Soc, 38, 297 (1989). Goddard, E. D., Phillips, T. S., Hannan, R. B.: J. Soc. Cosmet. Chem., 26, 461 (1975). Goddard, E. D., Hannan, R. B.: J. Am. Oil Chem. Soc, 54, 561 (1977). Harusawa, P., Kato, S., Tanaka, M.: J. Soc. Cosmet. Chem. Jpn., 15, 225 (1981). Noda, A., Yamaguchi, M., Machida, Y., Fukushima, S.: J. Soc. Cosmet. Chem. Jpn., 20, 103 (1986). Harusawa, F., Nakama, Y., Tanaka, M.: J. Soc. Cosmet. Chem. Jpn., 25, 111 (1991). Harusawa, P., Nakama, Y., Tanaka, M.: Cosmetics and Toiletries, 106, 35 (1991). Nakama, Y., Harusawa, P., Murotani, I.: J. Am. Oil Chem. Soc, 67, 17 (1990). Japan Official Regulations Association, ed.: Guidelines for the Production of Pharmaceutical Agents, Yakugyojihosha, 1986. Hamilton, J. B.: In the Biology of Hair Growth, p.400. Academic Press, New York, 1958. Adachi, K.: Curr. Probl. Dermatol., 5, 37 (1973). Ellis, R. A.: In the Biology of Hair Growth, p.469. Academic Press, New York, 1958. Scott, E. J., Eckel, T. M.: J. Invest. Dermatol., 31, 281 (1958). Bruchovsky, N., Wilson, J. D.: J. Biol. Chem., 243, 2012 (1968). Takayasu, S., Adachi, K.: J. Clin. Endocrinol. Metab., 34, 1098 (1972). Takayasu, S., Adachi, K.: Endocrinology, 90, 73 (1972). Adachi, K.: J. Invest. Dermatol., 62, 217 (1972). Uzuka, M., Pukushima, S.: Fragrance J., 11 (1), 28-31, 36 (1983). Toshitani, T.: Fragrance J., 17 (5), 61-65 (1989). Falco, O. B.: Arch. Klin. Exp. Dermatol., 227, 419 (1966). Ogawa, H., Hattori, M.: Normal and Abnormal Epidermal Differentiation, pp. 159-170, University Tokyo Press, Tokyo, 1982.

438 New cosmetic science 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42.

Van Neste, D., Lachapelle, J. M., Antoine, J. L.: Trends in Human Hair Growth and Alopecia Research, pp. 94-98, Kluwer Academic PubUshers, UK, 1989. Takayasu, S., Adachi, K.: Endocrinology, 90, 73 (1972). Uno, H., Kemnitz, J. W., Cappas, A., Adachi, K., Sakuma, A., Kamoda, H.: J. Dermatol. Sci., 1, 183-194 (1990). Wetterings, P. J. J. M. et al.\ Acta Derm. Venereol. (Stockholm), 63, 315 (1983). Jahoda, C , Oliver, R. F.: Br. J. Dermatol., 105, 623 (1981). Sugiura, M., Ueda, H.: Modem Cosmetic Science, Hirokawa Shoten Co., 1984. Soc. Cosmet. Chem. Jpn., ed.: Modern Cosmetic Science, Yakuji Nipposha Ltd., 1979. Sagarin, E. et al, eds.: Cosmetics-Science and Technology, 2nd edn., p. 178, Wiley Interscience, 1972. Bendit, E. G.: Fibrous Proteins, 2, 115 (1980). Japan Permanent Wave Lotion Industry Association, ed.: The Science of Hair and Permanent Waving, p. 97, 1989. Hirose: Fragrance J., extra edn. No. 8,110-112, 109 (1987). Arai, Y., Torii, K.: Fragrance J., 19 (6), 14-18 (1991). Vallko, E. I., Bamett, G.: J. Soc. Cosmet. Chem., 3, 108 (1952). Kass, G. S.: Am. Perfum. Aromatics, 47, Sept. (1956). Stead, C. V.: Am. Perfum. Cosmetics, 79, 31 (1964). Goldemberg, R. L., Tucker, H. H.: J. Soc. Cosmet. Chem., 19, 423 (1968). Corbett, J. F.: Cosmetics and Toiletries, 91, 21 (1976). Blankenburg, G., Philippen, H., Baurschmidt, P., BoUert, V.: J. Soc. Cosmet. Chem., 37, 59 (1986). Corbett, J.,F.: J. Soc. Cosmet. Chem., 23, 683 (1972). Kiese, M., Rauscher, E.: Toxicol. Appl. Pharmacol., 13, 325 (1968). Robbins, C. R.: Chemical and Physical Behavior of Human Hair, p.l29. Van Nostrand Reinhold Co., 1979.

4 Fragrance products Fragrance products are those which focus on fragrance and includes perfume, eau de parfum, eau de cologne, fragrant powder, solid perfume and perfumed soap.

4.1. Types of fragrance product The most popular are perfume and eau de cologne but there is also a great variety of other products as shown in Table 4.1. In addition to these, there are also such cosmetic products as body lotion and bath oil and such miscellaneous ones as pot pourri and candles which have been impregnated with a fragrance.

4.2. Perfume Perfume consists of a fragrance compound dissolved in ethyl alcohol. It is said that perfume in this form first appeared in the 14th century in Hungary. It was known as Hungary Water and used by the Queen of Hungary to stay young. Nowadays, ,a great many cosmetics contain fragrance compounds. Perfume occupies the highest position among such products and has been highly esteemed throughout history. Perfume is art using fragrance and has been likened to beautiful music and paintings. For this reason, perfumers should have the sensitivity of an artist. Good perfumes should satisfy the following requirements: Table 4.1. Types of fragrance product Product

Perfume dosage

Perfume, Parfum

15'-30%

Eau de Parfum

7—15

Eau de Toilette

5-10

Eau de Cologne

2- 5

Solid Perfume

5-10 1— 2

Fragrant Powder

1.5— 4

Perfumed Soap

439

440 New cosmetic science

(1) (2) (3) (4) (5) (6)

be in keeping with the product concept have beautiful and sophisticated scent have newness and originality be in good harmony diffuse well have an appropriate lasting quality

4.2.1. Manufacturing methods for perfumes 4.2.1.1. Manufacturing methods Perfumes are made by mixing a finished fragrance compound with ethyl alcohol in fixed proportions. Normally, the fragrance compound is dissolved in the alcohol without using a solubilizer so it is necessary to pay great attention to the solubility of the ingredients. The alcohol concentration is determined in consideration of the type of fragrance and the solubility of the fragrance materials used. After mixing, the perfume is kept in a sealed container made of a highly stable material like stainless steel and left to mature for a fixed period of time in a cooled darkened place. The length of the maturing period depends on the type of fragrance. When the maturing process is over, the perfume is filtered to remove any precipitate and the resulting clear liquid is put into bottles. The filtering is carried out under pressure using filter paper. The filtering conditions vary depending on the type of perfume. As perfume and eau de parfum have a high perfume concentration, it is necessary to take care against discoloration. The use of coloring agents is not widespread but they may be used if required. 4.2.1.2. Maturing Maturing removes the very irritating smell of alcohol and produces a very smooth and mellow scent. During the maturing process, the ester formation, ester exchange, acetal formation, acetal exchange, autoxidation, polymerization, and other chemical reactions that take place are bound up with each other in a very complicated way. Although each of the many different types of reaction are minute in scale, cumulatively they give rise to the changes that take place in the maturating process and are thought to produce the smooth, mellow scent. Generally speaking, perfumes containing water mature more easily. 4.2.2. Alcohol used for perfumes Ethyl alcohol is the alcohol normally used for perfumes. The two types of ethyl alcohol sold are Natural Class and Synthetic Class. The two concentrations are 99.5% (anhydrous) and 95-96% (contains water). The latter is the main one used for perfumes. Eau de Colognes use the same or lower concentrations. As ethyl alcohol is also a drink, substances are added to that used for perfumes to give it a smell and a bitter taste in order to prevent people from drinking it. Such substances are called denaturants. The denatured alcohol formulations normally used in cosmetic products are those stipulated in the Government regulations in each country. The denaturants permitted by different countries varies so it is necessary to keep this in mind when making perfumes for a particular country.

Fragrance products

441

4.2.3. Classification of perfume Perfumes are classified according to their scent characteristics and by marketing category. Scent characteristics are further classified according to fragrance type and by genealogy which traces the history of the scent in generation order. By marketing, perfumes are broadly classified into prestige line products and mass marketed products for the general consumer. In addition to these categories, there is also a group of products called designer fragrances. Such fragrances have the names of famous designers like Ungaro, Oscar de la Renta, Kenzo and Liz Claiborne and are intended to give the finishing touch to fashions designed by them. And now there are also fragrances on the market which have the names of celebrities, which are sometimes called celebrity fragrances. An example of this is EUzabeth Taylor's Passion. There are many charts for the classification of fragrances which are based on the most Table 4.2. Major families of perfume and scent characteristics Major family

Scent characteristics

Typical products

Citrus

Scent of lemon, bergamot, orange, grapefruit, lime and other citrus 4711 Shower Cologne fruits Fresh Lime Gives a fresh, refreshing feeling

Green

Combination of floral scent and one with a feeling of something green like the scent when green leaves or grass are rubbed with the fingers or the green note of hyacinth. Refreshing and natural scent which reminds one of fields and woods Gives a more characteristic and deluxe feeling than citrus

Fidji

Single floral

Scent of one particular flower like a rose, jasmin, lily of the valley, muguet, lilac or gardenia Gives a simple and refreshing feeling Casual scent with a western feeling

Diorissimo

Floral bouquet

Scent of a bouquet with many flowers in it A modern scent with a deluxe feeling Gives a feminine softness, elegance and a mellow feeling

L'Air du Temps

Floral aldehyde Scent of flowers with aldehyde accent Scent with feminine softness and elegance as well as a romantic feeling

Chanel No. 5

Chypre

A scent featuring a combination of oakmoss, bergamot, jasmin, rose, woody, musk, etc. Characteristic scent giving the feeling of a mature woman

Miss Dior

Floriental

Scent combining the softness of the floral type with the character and strength of the oriental type

Poison

Oriental

A scent having strong woody, powdery, animal and spicy features Opium -one for the mature woman giving a strong feeling of character, charm and sensuality

There is also a perfume inconporating Leather and Tabac ; typical producot : Cabochard

442 New cosmetic science Table 4.3. Perfume subfamilies and scent characteristics Subfamily

Scent characteristics

Fruity

Odor of fruits other than citrus fruits Typical ones are strawberry, peach, grape, apple and cassis

Aldehydic

Strong pervasive note of fatty aldehydes. Using it in small amounts in perfume brings out its depth and power.

Powdery

Powder-like note. Gives a mature and feminine image. Vanillin, heliotropin and musk are typical examples.

Woody

Odor of woods and trees. Gives a feeling of depth. Sandalwood, cedarwood, patchouli and vetivert are typical examples.

Mossy

Odor of the moss on oak trees. Suggestive of the damp atmosphere in a forest.

Spicy

Piquant, spicy note. Clove, pepper, cinnamon, nutmeg, rosemary, thyme and carnation are typical examples.

Leather tabac

Masculine note of leather and tobacco. Gives a refreshing feeling of masculinity.

Balsamic

Resinous note. A scent with a heavy, sweet depth

Animal

An animal note - the scent of musk, amber, civet or castoreum. Gives a sexy and charming image.

important scent characteristics. An example of this is given in the following. There are 8 major families under fragrance type. These major families and a description of their scents are given in Table 4.2. Table 4.3 describes the odors of the subfamilies and classifies the perfumes according to their scents. Table 4.4 shows this in two dimensions. 4.2.4. Choosing a perfume People can normally distinguish between 4 to 5 types of perfume at one time. If there are more than this, they become unable to tell the difference between them. The scent should not be smelt directly from the open bottle: a few drops should be placed on the back of the hand or the inside of the wrist and the scent sniffed lightly by gently wafting it towards the nose with the hand from a little distance away, after allowing the alcohol to evaporate. As it is heated by the hand, an idea of what the scent will actually be like when used on the body can be obtained. 4.2.5. Wearing perfume People "wear" perfume on their bodies. The best way to wear perfume is to spray it on to clean skin using an atomizer. It is also very good to apply it directly to the skin at such places as the inside of the wrists, elbows and knees. 4.2.6. Keeping a perfume at its best Although perfume is normally used up very quickly, in order to keep it at its best, attention should be paid to the following points:

Table 4.4. Classification of perfume Major family

I Citrus

I1 Green

111 Single floral

IV Floral bouquet

V Floral aldehydic

Refreshing

Natural

Purity

Elegance

Romantic

I.:ternity Liz Claiborne Anais Anais I'aris Clandestine Icenzo Giorgio

Calandre Chloe Charlie White Linen Nah6ma

1711 Shower Cologne Fresh Lime

1

Citrus

2

Green

Grass

3

Fruity

Fruits

Diorissimo

Alliage

4

Floral

Flowers

Floral aldehydic

Flower aldehyde

6

Aldehydic Aldehyde

7

Powdery

Powder

8

Woody

Wood sandalwood

9

Mossy

Moss

10 Spicy

Spice

Leather l1 Tabac

Leather, Tobacco

12 Ralsamic

Pine resin

13 Animal

Animals

Eau Sauvage Cristalle O de Lanc6me Ivoire Eau d'IIermes ERLIde Eau de Rochas Givencliy Tosca

Rive Gauche

JOY

Jardins de Bagatelle Eau de Fleurs Lln Juur Nina Byzance

Chanel No. 19 Amazone

Ombre Rose

Diorella

Zen Gucci No. 3

Eau de Colog- Fidji ne Hermes

Murasaki Beautiful Listen

L'Air du Temps

VI Chypre

Vlll Oriental

Warm, sensual Charming, sexy C h ~ ~ f ~ ~ ~ ~ i c ' Shalimar Givenchy 111

Chamade

Mitsouko Femme

Poison

Knowing

Loulou Oscar de la Kenta Angelique

Chanel No. 5 Arpgge

Y

Fleurs de Kocaille L' Aimant Sophia

hliss Dior hla Griffe

Madame Rochas Sanisara CalPche First Irnprevu L'Insolent Super Estee

Parure

Scandal

Cahochard

KL

Ysatis Parfum d'Hermes

VII Floriental

Intimate La Nuit

Cinnabar L'Origan

hlagie noilPaloma Picasso

Ombre Hleue Joop Nuit d'Ete Coco Houcheron Hijan

Ral A Versaille Missoni

Joop

Jicky Vol de Nuit Opium Tabu

Roma

Obsession Must de Cartier MystPre de Kvchas Musk

Table 4.5. Classification of men's cologne

1

Citrus

I

11

111

IV

v

VI

VII

VIM

IX

Citrus

Green

Lavender Fougere

Floral Rouquet

Woody

Chypre

Herbal Spicy

Leather Tabac

Musk

4711

Auslese

Monsieur de Givenchy 2

Green

3

Fruity

4

Lavender

5

Fougsre

6

Floral

7

Woody

8

Mossy

Lacoste

9

Herbal Spicy

Pour Hornrne (Capucci)

10

Leather Tabac

Portugal

11 Animal 12 Musk

Bravas Kicci Club Liz Claiborne for Men Pour Hotnme (YSL) Jazz

I'our Homme (Azzaro) Eau Sauvage

Valcan

Drakkar Noir Aramis rlevin Tactics

Tuscany

Kalafre

Fahrenheit

Eternity for Men

Tiffany for Men Monsieur Carven

Cool Water Santos Paco Rabanne pour IIomlne

Antaeus

I'oui- hlonsieur (Chanel)

New West

Aramis

Aramis 900

Gentleman Egoiste

Jules Royal Copenhagen Polo

-

Monsieur Kochas Kouros Musk for hlen

Fragrance products

445

Table 4.6. Major families of men's cologne and scent characteristics Scent characteristics

Major family

Typical products

Citrus

Citrus scents such as bergamot, mandarin orange, lime, petit grain and grapefruit. Gives a refreshing and clean feeling.

Eau Sauvage

Green

Combination of a floral scent and one of greenness like the one when you rub leaves or grass - a scent conjuring up the refreshing feeling of nature ; has a more characteristic and deluxe feeling than citrus.

Fahrenheit

Fougere

A scent originating from Fougere Royal ; combination of laven- Azzaro Pour Homme der and coumarin

Floral

Scent of a bouquet with many flowers in it ; a modern scent with a feeling of luxury, mellowness and elegance

Woody

A scent of trees which gives a feeling of depth. Sandalwood, cedarwood, patchouli and vetivert are typical examples.

Jazz

Herbal Spicy

Piquant odor of herbs and spices.

Paco Rabanne Pour Homme

Chypre

A scent featuring a combination of oakmoss, bergamot, jasmin, rose, musk with a characteristic feeling of individuality

Polo

Leather Tabac Masculine notes of leather and tobacco. Gives a refreshing feeling with a sense of masculinity.

(1) (2) (3)

Aramis

Avoid direct sunlight. An off-odor or discoloration will arise from degradation of perfume constituents resulting from increases in temperature due to the sun's rays and the effect of ultraviolet radiation. Avoid places with high temperatures or great temperature fluctuations. High temperatures make perfume deteriorate by causing chemical changes in it.

4.3. Men's cologne An Italian called Johann Maria Farina is said to be the father of Eau de Cologne. The story goes that Farina set up a company in the city of Koln (Cologne in French) and started to sell the first eau de Cologne in 1709. It is said that Napoleon loved to use eau de Cologne and took lots of it with him to the battlefield. Men's cologne originated from eau de Cologne. Compared to women's cologne, it is stronger and tends to have a very characteristic fragrance. There are many different classifications as in the case of women's fragrances. Table 4.5 gives a two-dimensional classification. Table 4.6 gives the main classifications and describes their scents. There are also other classifications which include the additional categories of aromatic.

5

Body cosmetics

Cosmetics for application to the body incorporate the widest range of products. They have a particular physiological effect on the different parts of the body they are used on and many of them have clearly defined functions. Table 5.1 classifies body cosmetics according to the parts of the body they are used on. Recently, with the increasing attention that people have been paying to health in beauty, there is a requirement for cosmetics to make the body shape more beautiful, and as a result, the new product area of Bodyline Care Cosmetics is now being developed.

5.1. Soap 5.7.7. History of soap Soap is a general term for higher fatty acid salts. The soaps that we use every day for washing ourselves are alkaline salts of C12-C16 fatty acids. Soap has an extremely long history and was apparently already being used for washing the body before the time of Christ. The first century scientist, Plinius made reference to it in his writings. The production of soap started in the 8th century in the Italian port town of Savona and this is the origin of the French word savon, the English word soap and the German Table 5.1. Usage and purpose of different types of body cosmetics. Where used

Whole body

Purpose

Typical products

Cleansing the body

Soap, body shampoo, exfoliating cleanser, bath oil, bath salts

Treatment

Lotion, miky lotion, cream

Fragrance

Powder, cologne

Suncare

Sunscreen, sunoil, after-sun lotion

Insect repellent

Insect repeller, mosquito screen

Hands (fingers)

Treatment

Lotion, cream

Whole leg

Discolor, depilatory

Discolor, depilatory cream, depilatory mousse

Elbows, knees

Softening

Horny layer softening lotion, gommage cream,

Leg (knee to ankle)

Prevent swelling

Leg freshener cream

Armpits

Deodorant, antiperspirant

Deodorant lotion, spray, powder, stick

446

Cosmetics and skin 447

word seifen. It was later made in Venice and other places and then a soap industry was started in Marseilles. The soap that was made was the excellent Marsel Soap produced from olive oil and seaweed obtained in the Mediterranean coast area. The seaweed was burned to make the alkali for the soap. Continuous improvements were made after that, and today there are a great variety of soaps on the market for both household and industrial purposes. 5.1.2, Raw materials of soap Many different oils and fats are used as the raw materials for soap and their use in formulae is decided with consideration for their characteristics and the purpose of the soap to be made. Table 5.2 shows the properties of soda soaps of individual fatty acids and Table 5.3, the fatty acid composition of natural fats and oils. The usual raw materials of soap are beef tallow and coconut oil and appropriate proportions for them are 60-80% and 2040%, respectively. Nowadays, palm oil may be used instead of beef tallow. The oils and fats to be used as raw materials are refined before use. The soaps that we normally use are made either by a saponification reaction of oils and fats with caustic soda or caustic potash, or through a neutralization reaction of fatty acids obtained through the splitting of oils and fats with caustic soda or caustic potash.

Table 5.2. Properties of fatty acid soda soaps.

Solubility

Detergency

Lathering

Hard ness of base

high

very low

lather coarse ; small amount (little lasting quality)

hard

high

(lauric acid)

very soluble in cold water

reasonably high

lather a little coarse ; large amount (medium lasting quality)

hard

high

(myristic acid)

soluble in cold water

high

lather fine ; large amount (excellent lasting quality)

hard

high

(palmitic acid)

sparingly soluble in cold water

high

lather fine ; medium amount (excellent lasting quality)

hard

high

(stearic acid)

insoluble in cold water

very high

hard but brittle

high

Cfs (oleic acid)

Very soluble in cold water

high

(linoleic acid)

Very soluble in cold water

medium

Fatty acid

Cio and below Ci3

u :i

lather fine ; small amount (medium lasting quality)

Stability

lather a little coarse ; large soft amount and (medium lasting quality) viscous

average

lather a little coarse ; medium amount (medium lasting quality)

readily changes

soft

448 New cosmetic science Table 5.3. Fatty acid composition of oils and fats. Saturated fatty acid % Oil or fat

Unsaturated fatty acid % Linolenic

Arachidonic

2.2

0.4

0.1

48.7

12.2

0.7

0.4

24.9

52.3

7.9

45.5

27.7

Oleic Linoleic

Ce

Cs

'^lO

v^l2

Ci4

0.2

8.0

7.0

48.2

17.3

8.8

2.0

6.0

2.5

3.0

3.0

52.0

15.0

7.5

2.5

16.0

1.0

Palm oil

1.0

42.5

4.0

43.0

9.5

Beef tallow

2.2

35.0

15.7

44.0

Lard

1.0

26.0

11.0

8.3

5.4

0.1

17.0

2.7

0.4

Coconut oil Palm kernel oil

Soybean oil 0.4

Rice bran oil

Ci8

C.6

^20

^24

1.0

Soap made using caustic soda is called hard soap while that made using caustic potash is known as soft soap. Bath soap is usually the hard variety. 5,13.

Soap manufacturing

methods

Soap manufacturing methods can be broadly divided into saponification and neutralization. In saponification, oils and fats (glyceryl esters of fatty acids) are hydrolyzed by an alkali producing soap and glycerin, after neutralization has taken place. In neutralization, soap is obtained by reacting fatty acids directly with an alkali. CH2-OH

CH2-00CR

I Saponification

CH-OOCR

+ 3 XOH

3RC00X + CH-OH CH2-OH

CH2-OOCR

Neutralization

RCOOH + XOH

-

RCOOX

H2O

X : Na, K

5.1.3.1, Soap base manufacturing methods (1) Saponification by boiling in a pan. With the development of continuous saponification and neutralization equipment in recent years, this method is now not used very much. However, something will be said about it here because it is a very traditional and basic method for making soap. This method produces a soap base through the processes of saponification, salting out, washing, final boiling and final salting out. First, a mixture of oils and fats is placed in a large reaction pan which is then heated. Next, while stirring, an aqueous solution of caustic soda is added which converts the oils and fats to fatty acid and glycerin. The fatty acid then reacts with the caustic soda to produce soda fatty acid, i.e. soap, and the glycerin mixes in with the water phase. This is the saponification reaction.

Cosmetics and skin 449 When the saponification reaction has finished, salt or saturated brine is gradually added, while continuously stirring, to remove the water, as soap is only sparingly soluble in brine. This process is called salting out. After salting out, the heating and stirring are stopped and the mixture is left for several hours or a few days, keeping the heat in. This causes the soap to separate and float up to the top. The waste liquid below it (mixture of salt, excess caustic soda, glycerin, water-soluble impurities, etc.) is then drained off from the bottom of the reaction vessel. The glycerin and salt can be recovered from this solution. As the soap still contains water, glycerin and a small amount of unsaponified matter, more brine, caustic soda and water are added and the mixture is heated, while stirring continuously. Through salting out (washing process) and the finishing processes (final boiling, final salting out), a very pure soap is obtained. As a result of these operations, the mixture inside the reaction pan separates into 3 layers: the neat soap (high purity molten soap containing around 30% water) at the top; the nigre soap (poor quality molten soap containing a lot of impurities); and the waste liquid, which again forms at the bottom. The neat soap at the top is removed and dried by heating to produce the soap base. (2) Continuous saponification methods. With the traditional saponification method described above, it takes a long time for the saponification reaction to finish, so it may take 3-5 days to obtain the neat soap. For this reason, the modern continuous saponification method, a high speed method in which the caustic soda is in uniform contact with the oils and fats, is now used. Examples of well-known continuous saponification methods are the Sharpies method, in which the oils and fats and caustic soda are in contact in a counter-current; the Monsavon method, which employs a colloid mill and effects saponification in an emulsion state; and the Unilever method in which the oils, fats and the caustic soda undergo saponification at high temperature by stirring them together using a steam jet injected into the mixture. (3) Neutralization method. In this method, the oils and fats are broken down into fatty acids and glycerin beforehand, and the fatty acids are neutralized through the action of alkali which produces the soap. The advantage of this method is that it takes less time to produce the soap because the salting out process of the saponification method is not required. But, the disadvantages are that as there is no cleansing through the salting out process, the fatty acids must be neutralized before they begin to deteriorate and glycerin or other additives must be added to raise the quality of the soap which is produced. However, as a result of the advances that have been made in continuous neutralization equipment, this method is also much used at the present time. (4) Ester saponification method. This method employs an ester exchange reaction of oils, fats and methyl alcohol by which methyl esters of the fatty acids are obtained (glycerin separated and recovered). Alkali is then added to carry out the saponification which produces soap and methyl alcohol. The advantages of this method are that the methyl alcohol can be recovered and recirculated, and the saponification reaction takes place very quickly. One of the disadvantages is that special equipment is required to recover the methyl alcohol.

450 New cosmetic science 5.1.3.2. Manufacturing solid soaps from soap base The soap base obtained as described above is cooled and a perfume and coloring are added to it. This is mixed well using a mixing machine, kneaded and compressed using a roll and a plodder, and molded into bar form. The bars of soap coming out of the machine are then stamped and wrapped. Soap produced in this way is called milled soap. There is also framed soap which is made by pouring the neat soap directly into molds and then cooling, solidifying, cutting and drying it. Nowadays, milled soap is the main type of toilet soap because framed soap cannot be easily produced on a continuous basis. 5.1.4. Properties of soap Soap is a strong alkaline salt of a weak acid and it is alkaline in an aqueous solution, having a pH of around 10. As soap is a type of surfactant, it reduces surface tension and interfacial tension and has lathering, dispersibility, emulsification and cleansing properties. The cleansing action of soap can be explained as follows: as an aqueous solution, it penetrates into the interface between the skin and the dirt to weaken its adhesion and make it easy to remove. The dirt is thus removed by physical forces and is then dispersed through the soap solution as a result of emulsification by the soap molecules. Some types of dirt may be removed by being solubilized in a micelle of the soap. Like other compounds which have long chain alkyl groups, soap exhibits polymorphism. Ferguson^) has classified the different forms as a, ^, d and co crystal forms. As the a form only occurs in low molecular weight soaps containing extremely little moisture, it does not form under normal production conditions, so the yS, d and a> forms are the major ones in soaps on the market. The o) form is often produced when a neat soap, like framed soap, is cooled as it is; there is a lot of the ^ form in milled soap. The d form, which occurs in a high molecular weight soap with a large moisture content, tends to appear especially when the temperature is low. Crystal form is one of the primary factors affecting the properties of soap, although there are others. 5.1.5. Types of soap 5.1.5.1. Toilet soap Toilet soap must be able to produce a good lather in both cold and warm water, must not swell when put in water, change shape when it becomes dry and produce any irritation. It must also have a pleasant fragrance. Milled soap almost satisfies all of these requirements but it tends to dissolve too quickly in warm water and is difficult to dissolve in cold water. Therefore, efforts are currently being made to overcome these problems by such means as adjusting the proportions of the oils and fats in formulae, and through the use of additives. Some soaps include higher alcohols, higher fatty acids and hydrocarbons, in small amounts of up to 10%, to give a creamier lather and protect the skin. These are known as superfatted soaps.

Cosmetics and skin 451 5.1.5.2. Transparent soap Like toilet soap, transparent soap usually consists mainly of soda salts of higher fatty acids (there are also types employing both potassium salts and triethanolamine salts) but their distinguishing feature is their great transparency. As for toilet soap, the raw materials used include beef tallow, coconut oil and olive oil, and in addition, castor oil is also often used to give transparency and plasticity. As the constituent fatty acids of these oils and fats are different, consideration is given to mixing them together so that properties appropriate to a transparent soap are maintained. With the same purpose in mind, fatty acids may also be added. To give the soap its transparent structure, glycerin, sugar, ethyl alcohol and other transparency agents are employed. As there is no salting out in the manufacture of transparent soap, the glycerin formed by saponification remains in the soap. This is taken into consideration when deciding on the formula for a transparent soap. To fulfill the same objective as glycerin, propylene glycol, sorbitol, polyethylene glycol, amphoteric surfactants and anionic surfactants are also added. As there are so many transparency agents and other additives in transparent soap, it contains less soap than ordinary toilet soap. Transparent soaps not only look attractive, many of them also protect the skin well and are mild to use because the glycerin and sugar used in them act as humectants. (1) Manufacturing method of transparent soap. As a special process is used for manufacturing transparent soap, the raw material composition in the finished product, after drying, is different from that when the raw materials are put into the reaction vessel. The formula given below is a typical one for the raw materials put into the reaction pan. Typical formula. Transparent soap Raw material formula Beef tallow Coconut oil Castor oil Olive oil Caustic soda Ethyl alcohol Purified water Sugar Glycerin Perfume Dye Sequestering agent

% 22.0 10.0 4.0 4.0 6.0 20.0 20.0 9.0 4.0 1.0 q.s. q.s.

After the saponification reaction has taken place and the transparent soap has solidified, it is dried and matured, and as a result, the water and ethyl alcohol gradually evaporate off. It is for this reason that the composition of the finished transparent soap is very different from that of the mixture in the reaction pan, and at this time the formula is probably something like the following:

452 New cosmetic science

Raw materials Oils and fats Ethyl alcohol Caustic soda solution Purified water Sugar

^SaponificationTj — • [Dissolution—•J—•[Coloring • perfuming] i and mixing] reaction] [Cooling, solidification] Adjust free alkali i [Cutting] i [Drying] i 40-60 days [Stamping] i

Polyols Pharmaceutical agent perfume, dye

•

[Finishing, packaging] i Transparent soap

Fig. 5.1. Manufacturing processes for transparent soap.

Finished product composition Fatty acid soap Sugar Glycerin Water Perfume Dye Sequestering agent

7(9

55.3 12.0 11.5 19.9 1.3 q.s. q.s.

Manufacturing procedure The general manufacturing procedure is shown in Fig. 5.1. (2) Crystal structure of transparent soap: Many points regarding the crystal structure of transparent soap remain to be clarified. However, McBain et al?^ have demonstrated using X-ray diffraction that transparent soap is made up of fine crystals. Transparency agents such as ethyl alcohol, glycerin and sugar play a part in the formation of these fine crystals. As is reported in detail in Ogino's^^ electron microscope study, transparency agents have an inhibitory effect on crystal formation in soap and it shows clearly that the structure consisting of long fiber-like crystals, characteristic of soap, is absent in transparent soap as the result of adding them. In soap molecules, the polar groups and hydrocarbon chains are horizontally aligned and this horizontal structure is built up in a multilayer structure vertically. It is thought that the addition of transparency agents strongly affects the van der Waals forces between hydrocarbon chains, suppressing crystal growth, which accounts for the fine crystal structure. In an X-ray diffraction study on transparent soap, Kamota et al^^ surmised that the addition of a transparency agent caused the fiber-like fine crystals in transparent soap to be divided up perpendicularly to the fiber axis and as these crystals are too fine to be observed under visible light, the soap appears transparent, the same conclusion arrived at by McBain et al?\

Cosmetics and skin 453 5.1.5.3. Syndetbar There are cleansing materials which are designed to improve lathering in hard water, prevent the formation of scum, and improve alkalinity. These are such synthetic detergents as acylisethionates, alkyl sulfates, fatty acid monoglyceride sulfates, A^-acyl-Lglutamates, alkyl-imidazoliniumbetaine-type amphoteric surfactants, which are used as major raw materials either by themselves, or in combination with soap. "Syndet bar" is a product in which these detergents are used by themselves and "combination bar" one in which they are used in combination with soap; both are widely used in Europe and the United States. However, they are not used much in countries like Japan with excellent water quality because they are highly priced, their lather becomes stale as it lasts too long, and they dissolve away too quickly in water under normal use. Despite this, attention is now being given to these types as a neutral soap for people sensitive to alkali such as those with eczema and babies with diaper rash. Typical formula 1. Syndetbar Sodium glyceryl monolaurate sulfate Glyceryl monostearate Cetyl alcohol Lanolin derivative Corn starch Perfume Dye Antioxidant, sequestering agent Typical formula 2. Combination bar Sodium glyceryl monolaurate sulfate Sodium lauryl sulfate Soap Cetyl alcohol Titanium dioxide Perfume Dye Antioxidant, sequestering agent

% 80.0 7.0 10.0 1.0 2.0 q.s. q.s. q.s. % 55.0 10.0 30.0 4.0 1.0 q.s. q.s. q.s.

5.1.5.4. Deodorant soap The purpose of deodorant soap is to reduce unpleasant body odor. It contains an antibacterial agent such as triclocarban or triclosan which kills bacteria on the skin and disinfects it. 5.1.5.5. Other soaps Examples of other soaps having special applications or appearances are floating soap, liquid soap, powder soap and paper soap.

5.2. Body shampoo Most important to skin hygiene is washing off the dirt on the skin's surface and main-

454 New cosmetic science

taining it in a clean condition. Cleansing products are used with this purpose in mind. Solid soap has the longest history as a general skin cleanser and is still widely used today for cleansing the body when taking a bath because of its low price and the refreshing feeling it gives. However, the demand for it has reached a peak and now with changing consumer lifestyles and their diversifying needs, it is becoming necessary to provide more than just cleansing functions in cleansing agents. In Europe and the United States, a product called bubble bath, which is poured directly into the bath to make bubbles, has been around for some time. Due to the differences in bathing customs, bubble bath has not become popular in Japan but along with the increase of baths and showers in the home, a product called body shampoo has come on the scene. Body shampoo produces a richer lather than solid soap, has a very attractive perfume and is more fun to use. In the early 1970s when body shampoo first appeared in Japan, having the status of a variation of bubble bath, it enjoyed a strong position among cosmetics. After that, with the increase in the use of showers, morning showers and bathing after sports activities, the circumstances of using skin cleansers underwent a change. As washing equipment became more diversified with the addition of such items as sponges and nylon towels, the use of body shampoo spread because its liquid form made it easier to use than conventional solid soap. Currently its price is at the level of toiletry products. As advances were made in skin physiology research, cleansing the skin came to be considered as an essential part of skin care and, as a result, safety and usefulness came to be sought in them. 5.2.1, Functions required of body shampoos 5.2.1.1. Lathering characteristics Body shampoo is required to clean the very large area of the whole body surface and produce a pleasing lather when used. It should therefore have a high lathering capability and produce a lather which is creamy, soft and long lasting. 5.2.1.2. Skin physiology and cleansing qualities Body shampoo is essentially for cleansing the skin on parts of the body other than the face, so skin physiology of the body^^ must be taken into account. Compared to the face, other parts of the body do not produce much sebum or sweat but there are apocrine glands which secrete body odor causing substances in areas with body hair. The lipids present on a healthy skin are those originating in the horny layer such as cholesterol and ceramides, and those secreted by the sebaceous glands such as squalene, triglycerides and fatty acids. These lipids form a film of sebum on the skin which protects it from its environment. However, after secretion, dust sticks to it, it is decomposed by skin surface bacteria and oxidized, producing dirt that needs to be washed off. There is also the problem of lipids being transformed into irritating lipid peroxides due to the action of ultraviolet radiation. The horny layer protects the body from external influences. Its cells are metabolized and finally flake off but if they should remain on the skin together with sebum and dust for a long period of time, this provides a breeding ground for bacteria which can cause

Cosmetics and skin 455

skin diseases. Water evaporating from sweat excreted by the sweat glands will also leave behind salt and urea which will irritate the skin. If the lipids secreted by the sebaceous glands are removed by washing they will be replaced in a short space of time but it takes much longer for lipids from the horny layer to be replaced. In addition, because horny layer lipids have a barrier function, a moisture retaining function and contribute to adhesion between horny layer cells, it is not desirable for a cleansing agent to penetrate into the horny layer and wash away these lipids. Body cleansers therefore, should exhibit a selective cleansing action by which the intercellular lipids in the horny layer are preserved as much as possible, the urea, salt, degraded lipid substances and the various kinds of dirt dispersed through this are removed effectively, and the propagation of bacteria and formation of irritant substances is prevented. The horny layer in the skin of healthy persons contains 10-20% moisture which gives elasticity and flexibility to the skin. This moisture is maintained by the sebum film, the horny layer intercellular lipids and natural moisturizing factors (NMFs). NMFs are composed of such substances as free amino acids, pyrrolidone carboxylic acid and lactic acid salts. It is not good to lose them through washing. Body shampoos should therefore be so designed that they do not upset the skin's physiological functions and should remove dirt only. 5.2.2, Types of body shampoo Body shampoos can be divided into transparent and non-transparent types (there are also pearl-look products). With respect to their formulation, they can be divided into 3 types: the alkaline type having liquid soap as their main ingredient (soap-type); the weakly acidic type having synthetic surfactants as the main ingredient (syndet-type); and the neutral type combining liquid soap and synthetic surfactants (combination-type). 5.2.3. Main ingredients of body shampoo 5.2.3.1. Foaming detergents The foaming detergents used in body shampoo should produce a creamy lather having sufficient quantity and lasting quality to clean the whole body and produce very little irritation. The foaming detergents which have been in general use up till now are anionic surfactants such as fatty acid soaps, alkyl sulfates, alkyl ether sulfates and a-olefin sulfonates; while, such foaming detergents as A^-acyl-methyl taurates, acylsarcosinates, alkyl sulfosuccinates, A^-acyl-L-glutamates, acylisethionates and mono-alkyl phosphates have been used to enhance safety and usefulness. Body shampoos containing surfactants other than soap as their main ingredients are thought to be difficult to rinse off in Japanese water and cause sliminess; hence most of them produced for the Japanese market contain fatty acid soap, or a combination of surfactants other than fatty acid soap and soap as their main ingredients. In Europe and the United States, it is normal for the main ingredients of body shampoos to be synthetic surfactants.

456 New cosmetic science

5.2.3.2. Promoters Using suitable amounts of non-ionic or amphoteric surfactants in combination with the main ingredients supplements their lathering capability, improves lather quality, helps to give a good feeling on use and improves hard water resistance. Typical examples of nonionic surfactants used as promoters are fatty acid alkylolamides and amine oxides. Amphoteric surfactants used are the alkyl betaine and imidazolinium betaine types. Non-ionic and amphoteric surfactants are used in many body shampoos because they reduce the irritancy of the main ingredients. 5.2.3.3. Stabilizers Surfactants are highly concentrated in many body shampoos because a large surface area has to be cleaned and a profuse lather is required. In view of this, it is necessary to include stabilizers in their formulae to maintain fluidity at low temperatures and prevent turbidity in the transparent type. These purposes are achieved through the selection of the counter ion and the use of polyols and fatty acid alkylolamides. As stabilizers against micro-organisms, ethanol and different types of paraben are used, whereas, dibutylhydroxytoluene and different types of vitamin E are used as stabilizers against oxidation. Typical formula 1. Soap type Laurie acid Myristic acid Palmitic acid Oleic acid Laurie acid diethanolamide Glycerin Caustic potash Purified water Perfume Dye Preservative, sequestering agent

% 2.5 7.5 2.5 2.5 5.0 20.0 3.6 56.4 q.s. q.s. q.s.

Typical formula 2. Combination type yo

Triethanol amine A^-lauroyl-L-glutamate (30% aqueous solution) Sodium A^-lauroylmethyltaurate (30% aqueous solution) Triethanol amine laurate Triethanol amine myristate Laurylimidazolinium betaine Laurie acid diethanolamide Propylene glycol Purified water Perfume Dye Preservative, sequestering agent

20.0 10.0 10.0 10.0 5.0 5.0 7.0 33.0 q.s. q.s. q.s.

Cosmetics and skin 457 Typical formula 3. Syndet type Triethanol amine lauryl sulfate (40% aqueous solution) Sodium polyoxyethylene (3) lauryl ether sulfate (30% aqueous solution) Laurie acid diethanolamide Glycerin monopalmitate Lanolin derivative Propylene glycol Purified water Perfume Dye Preservative, sequestering agent

% 40.0 20.0 5.0 1.0 2.0 5.0 27.0 q.s. q.s. q.s.

5.3. Suncare products In Part I, we discussed the effect of ultraviolet radiation on the skin. Protecting it from the harmful effects of UV is one of the major tasks for skin care and body care products. The main purpose of suncare products is to protect the skin from ultraviolet rays and minimize its harmful effects on the skin. They include products for the treatment of skin which has been exposed to UV and can be divided into the following groups: (1) Suntan cosmetics which prevent erythema by cutting out UVB and enable the skin to be tanned an attractive suntanned color. (2) Sunscreen cosmetics which cut out UVA and UVB and prevent skin reactions to ultraviolet rays. (3) After suncare cosmetics for treating the skin after being sunburnt. Self-tanning products which give the skin a suntanned color in the absence of ultraviolet rays and pre-tan enhancers also come under the category of suncare products. Owing to concern about the photoaging of the skin and other long-term effects of UV, a new product category called sun-protect skin care has recently come into being. It comprises products for daily use which combine skin care and suncare functions. 5.5.7. Methods for assessing protection against ultraviolet rays 5.3.1.1. Sun protection factor The sun protection factor (SPF) is normally used to assess protection against UV for human skin. To measure the SPF, some of the sample is spread on the skin which is then exposed to ultraviolet light. It is then calculated as the ratio of the minimum erythema dose (MED; minimum amount of UV that causes faint redness) of the part with the sample on it, to the MED of a part with none of the sample on it according to the following formula: cpp_ MED of part with sample ~ MED of part with no sample

458 New cosmetic science

If there are differences in the light source, amount of sample applied or sensitivity of the subject to UV, the value of the SPF will vary. For this reason, different countries have their own standards for the measurement of SPF. The standards for measuring SPF in the US, Germany and Australia are the FDA standard^) of 1978, the DIN standard^) of 1983 and the revised AS 2604^) of 1986, respectively. The one used in Japan is Standard for SPF Measurement^^ which was drawn up by the Japan Cosmetic Industry Association in 1991. As SPF assesses the skin's reaction to UVB (erythema), it is a precise indicator of the protective effect against UVB. Although methods of assessing protection against UVA have been described in a number of research reports^^'^^^ such methods have still to be unified. Owing to the fact that the skin of people is used to measure SPF, it is difficult to obtain frequent measurements for a large number of samples. In view of this, a number of methods for assessing the protection against UV in which the SPF can be estimated to a certain extent, are under consideration. 5.3.1.2. Diluted solution transmittance method In this method, sunscreen agents are dissolved in a solvent or made into a dispersion, and their transmittance and absorbance are measured. However, as this situation is totally different from that in which a sunscreen agent is applied directly to the skin, it shows poor correspondence with the SPF. Despite this, it is still considered to be useful for a preliminary assessment as, due to its simplicity, a great many samples can be tested. 5.3.1.3. Thin film transmittance method A thin film of the sample is applied to a quartz plate in order to analyze the transmittance spectrum. Being closer to applying samples to real skin, this method is slightly more accurate than the diluted solution transmittance method 5.3.1.4. Removed epidermis transmittance method^^^ A sample is applied to epidermis removed from the hairless mouse. This is exposed to ultraviolet light and the transmitted light measured to assess the degree of protection against UV. It shows good correspondence with the SPF method. 5.3.1.5. Measurement on guinea pigs^^^ This is a testing method using Hartley guinea pigs instead of humans which is carried out in conformance with the SPF method. Although this is a very useful method because the results show very close correlation with the SPF, it is only considered suitable for preliminary assessments as unnecessary animal testing should be avoided. 5.3.1.6. Using SPF analyzer^^^ The sample is applied uniformly to a special film which is exposed to an artificial light source. The transmitted light is measured and multiplied by a factor corresponding to the contribution of the artificial light to the skin reaction (erythema) at each wavelength, in order to estimate the SPF.

Cosmetics and skin

459

5.3.2. Types of suncare base The different types of suncare product bases are the emulsion type, lotion-type, oil-type, gel-type (oily and aqueous gels), aerosol-type and stick-type. The following describes the features of each type. (1) Emulsion-type (a) O/W emulsion. This base is the one most often used. It is easy to stabilize and Ultraviolet absorbents can be readily incorporated. Though it has less water resistance than the W/0 emulsion and oil-type bases (Fig. 5.2), it feels good on the skin and can be made into products with SPFs ranging from low to high values. (b) W/O emulsion. Not as good as the O/W emulsion base in terms of its feeling on the skin and stability but excellent in terms of water resistance and UV protection. (2) Lotion-type. This type is liked for its non-sticky feeling on the skin but it is difficult to incorporate the large amounts of ultraviolet absorbents required to achieve a protective effect and the water resistance is not very high. (3) Oil-type. The oil-type has good water resistance but gives less protection against UV than the emulsion-type. It is therefore used a lot as a base for low SPF products. (4) Gel-type (a) Aqueous gel. Similar in nature to the lotion-type but is easier to apply to the skin due to its high viscosity. (b) Oily gel. Limited application due to its heavy oily feeling but it has high water resistance. (5) Aerosol-type. The aerosol-type base is good for mousse and aerosol form products but, being used under high summer temperatures, there is the risk of gas leaking from pressurized cans and them exploding. However, with the recent development of a type which does not use gas, we can expect it to be used more and more.

c O

< 250

300

350

250

300

350

250

300

350

Wavelength : nm

Wavelength : nm

Wavelength nm

W/0 emulsion base

Oil type base

O/W emulsion base

Fig. 5.2. Water resistance of different bases. -, before washing, , after washing. The water resistance was assessed by measuring the absorbance (taking this as an indicator for the ultraviolet absorbent in the sample) of ethanol extracts of the sample on the skin taken before and after immersion in water.

460

New cosmetic science

(6)

Stick-type. This type does not spread well so it is not suitable for use on the whole body but a high degree of UV protection can readily be obtained making it suitable for parts of the body which are easily sunburnt like the nose and cheeks.

5.3.3. Types of suncare product 5.3.3.1. Sunscreen cosmetics The purpose of sunscreen products is to prevent the skin from tanning and burning by screening out the UVA and UVB in sunlight. A description of ultraviolet absorbents will be omitted here because one is given in the chapter on materials in Part I (refer to Part I, 5.5, Ultraviolet Absorbents) Ideal sunscreen products should have the following qualities: (1) They should provide adequate protection against ultraviolet rays. (2) They should be highly safe. (3) They should not be removed by sweat or water. (4) They should not produce a feeling of discomfort. (5) They should not stain clothes. Water resistance is a very important characteristic for sunscreen cosmetics to have. The W/O emulsion base is normally used to enhance water resistance. However, as described above, it is necessary to take the feeling on the skin and stability fully into account when using it. Water resistance has been raised through the addition of silicones for a very long time. As well as having good water resistance, low viscosity silicones also improve the feeling on the skin. Typical formula 1. Cream-type (0/W emulsion) Water phase

Oil phase

Purified water 1,3-butylene glycol Titanium dioxide Disodium editate Triethanol amine 99% Oxybenzone Octylmethoxycinnamate Squalane Petrolatum Stearyl alcohol Stearic acid Glyceryl monostearate Ethyl polyacrylate Antioxidant Preservative Perfume

%

54.95 7.0 5.0 0.05 1.0 2.0 5.0 10.0 5.0 3.0 3.0 3.0 1.0 q.s. q.s. q.s.

Manufacturing procedure Make solutions of the oil and water phases at 70°C. After ensuring that the titanium dioxide is well dispersed in the water phase, add the oil phase to it, and make into an emulsion using a Homomixer. Cool the emulsion using a heat exchanger.

Cosmetics and skin 461 Typical formula 2. Milky lotioni-type (0/W Water phase

Oil phase

emulsion)

Purified water Dipropylene glycol Ethanol Hydroxyethylcellulose Octylmethoxycinnamate Glyceryloctyl-diparamethoxycinnamate 4-tert-Butyl-4'-methoxydibenzoylmethane Oxybenzone Oleyl oleate Dimethylpolysiloxane Petrolatum Cetyl alcohol Sorbitan sesquioleate Polyoxyethylene(20)oleyl alcohol ether Antioxidant Preservative Perfume

% 68.2 6.0 3.0 0.3 6.0 2.0 2.0 3.0 5.0 3.0 0.5 1.0 0.8 1.2 q.s. q.s. q.s.

Manufacturing procedure See formula 1.

Typical formula 3. Cream-type (W/0 emulsion) 70

Water phase Oil phase

Purified water 1,3-buty lene glycol Octylmethoxycinnamate Oxybenzone 4-tert-butyl-4'-methoxydibenzoylmethane Hydrophobic titanium dioxide Squalane Glycerin di-isostearate Organophylic montmorillonite Preservative Perfume

38.5 5.0 5.0 3.0 1.0 3.0 40.0 3.0 1.5 q.s. q.s.

Manufacturing procedure Make solutions of the oil and w^ater phases at 70°C. Ensure that the titanium dioxide is well dispersed in the oil phase and then put it in a Homomixer and add the water phase to make the emulsion. Cool the emulsion using a heat exchanger. 53.3.2. Suntan cosmetics Suntan cosmetics prevent the erythema due to UVB in sunlight and give the skin a uniform, attractive suntanned color. The ultraviolet absorbents used are therefore mainly those which block UVB. The most commonly used base is the oil-type but the emulsiontype, gel-type and lotion-type bases are also frequently used. As these products are often used on the beach, it is desirable to minimize the sticky feeling and adhesion of sand

462 New cosmetic science

a. Water droplet on skin to which suntan oil containing silicone resin has been applied

b. Water droplet on skin to which non-silicone resin containing suntan oil has been applied

Fig. 5.3. Comparison of water repellence for different suntan oils. characteristic of the oil-type. It is therefore good to use oils to which sand does not adhere and give a refreshing feeling when making up the formulae. Water resistance is another important requirement for suntan cosmetics. The use of film formers is an effective way of enhancing the water resistance. Fig. 5.3 shows the water repellence of a formula in which silicone resin has been used as the film former. Typical formula 1. Oil-type Octylmethoxy cinnamate Mineral oil Cetyl octanoate BHT (antioxidant) Perfume

% 2.0 70.0 28.0 qs. qs.

Manufacturing procedure Mix the ingredients together in the order given above, while stirring to ensure full dissolution. Typical formula 2. Oil type Octylmethoxy cinnamate Mineral oil Isopropyl myristate Silicone oil Silicone resin BHT (antioxidant) Perfume

%

1 -5 56.5 10-0 30.0 2.0 qs. QS.

Manufacturing procedure Dissolve the silicone resin in the silicone oil. Next add the isopropyl myristate and after thorough mixing, add the remaining ingredients and stir.

Cosmetics and skin 463 Typical formula 3. Gel (oily-type) % 2.0 73.0 20.0 5.0 q.s. q.s. q.s.

Octylmethoxy cinnamate Mineral oil Olive oil Organophylic montmorillonite BHT (antioxidant) Perfume Colorant

Manufacturing procedure Put the organophylic montmorillonite in some of the mineral oil and after it has swelled, stir vigorously to make a uniform dispersion. Add the remaining mineral oil and the rest of the ingredients to this and make into a uniform mixture. Typical formula.

Lotion % 51.0 5.0 10.0 10.0 20.0 3.0 1.0 q.s.

Purified water Dipropylene glycol 1,3-buty lene glycol Polyethylene glycol 400 Ethyl alcohol Polyoxyethylene(60)-hydrogenated castor oil Octylparamethoxy cinnamate Perfume

Manufacturing procedure Make a solution of the polyoxyethylene(60)-hydrogenated castor oil, octylmethoxy cinnamate and the perfume in the ethyl alcohol (alcohol phase). Next, make a solution of the remaining polyols in the purified water, ensuring thorough dissolution (water phase). Add the alcohol phase to the water phase and stir thoroughly. Typical formula 5. Milky lotion-type (0/W Oil phase

Water phase

emulsion)

Octylmethoxy cinnamate Isopropyl myristate Oleyl oleate Petrolatum Stearyl alcohol Stearic acid Glyceryl monostearate Vitamin E acetate Preservative Perfume Purified water 1,3-buty lene glycol Carboxyvinyl polymer Triethanol amine

% 3.0 2.0 4.0 2.0 1.0 2.0 2.0 q.s. q.s. q.s. 77.8 5.0 0.2 1.0

464 New cosmetic science

Manufacturing procedure Make separate solutions of the oil phase and water phase ingredients at 70°C. Add the oil phase to the water phase and make into an emulsion using a homogenizer. Cool the emulsion using a heat exchanger. 5.3.3.3. After-sun care products Exposure to strong ultraviolet radiation will cause erythema in the skin and after a few days delay, pigmentation and peeling. It has been reported that when this happens, the amount of moisture in the horny layer is less than in parts which have not been exposed to UV and that the amount of free amino acids in it decreases^^\ After-sun care cosmetics are designed for skin which has been exposed to strong ultraviolet radiation. Preparations such as carmine lotion (refer to Part II, 1.3.4.4: Multilayer Toilet Water, Formula 2) and aqueous gels, which contain powders like zinc oxide and anti-inflammatory agents are effective against temporary inflammations like erythema. Furthermore, lotions and milky lotions with a strong moisturizing effect are very necessary for skin which has lost moisture. Ascorbic acid and its derivatives, and placenta extract have been in use for a very long time to help the skin recover from pigmentation due to UV exposure but it is now known that arbutin, a constituent of blueberries, and kojic acid, a constituent of malted rice, are also very effective in this respect.

5.4. Hand care products Hand care products are for cleaning and treating the hands. They comprise such items as soap, hand cream and nail care products. One of their purposes is to prevent roughness in the hands. Skin roughness may be caused by drying or doing work using water. Other purposes are whitening and blocking ultraviolet radiation. There are two types: a cream type with a strong moisturizing effect to prevent the skin drying out; and a roughness preventing, water repellent type which is put on the hands before doing work involving water to prevent them from coming into direct contact with it. In order to give the moisturizing cream type a humectant action, various types of humectant and petrolatum are used in the formula. Silicone oils and silicone polymers are used to give the roughness preventing type its water repellence. Suitable emulsions are the lotion type and the W/0 type. In addition to humectants and petrolatum, pharmaceutical agents like urea, anti-inflammatory agents and vitamins should be included in the formula for products used to alleviate conditions in which the roughness has become so bad that the skin is cracking. In order to keep the hands looking white, some products use ultraviolet screening agents, as well as whitening agents like placenta liquid, vitamin C and vitamin C derivatives. Typical formula 1. Hand roughness preventing lotion 70

Polyphenylmethylsiloxane

5.0

Cosmetics and skin 465 Ethyl alcohol Perfume Typical formula 2. Moisturizing

94.8 0.2 cream

Purified water Glycerin 1,3-buty lene glycol Caustic potash Stearic acid Stearic acid monoglyceride Cetanol Liquid paraffin Petrolatum

% 64.75 15.0 3.0 0.25 3.0 3.0 2.0 6.0 3.0

Typical formula 3. Hand cream Purified water Glycerin Urea POE(60)isostearic acid glyceride Stearic acid monoglyceride Cetanol Petrolatum Liquid paraffin V-E acetate Vitamin D

58.0 20.0 2.0 2.5 1.5 4.0 2.0 10.0 q.s. q.s.

Typical formula 4. Whitening milky lotion Purified water Glycerin 1,3-butylene glycol POE(10)behenyl alcohol ether Sorbitan sesquioleate Cetanol Petrolatum Liquid paraffin 2-Hydroxy-4-methoxybenzophenone Octylmethoxy cinnamate Glcyrrhizinic acid V-C derivative Placenta liquid

% 78.0 8.0 4.0 2.0 2.0 2.0 1.0 3.0 q.s. q.s. q.s. q.s. q.s.

Manufacturing procedures Please refer to the general manufacturing procedures for creams and milky lotions in the chapter on Skin Care Cosmetics.

466 New cosmetic science

5.5. Deodorant cosmetics Deodorant cosmetics are applied to skin to prevent unpleasant body odor. The main forms they come in are liquids, aerosols, ointments, gels, powders, powder cakes and sticks but the most common ones are powder-containing aerosols and liquids. 5.5.7. Body odor The different types of body odor are sweat odor, underarm odor and foot odor which are caused by the action of skin bacteria on sweat. As described in Part I 1.1.4, sweat is excreted by the sweat glands, of which there are two types, eccrine and apocrine glands. Eccrine glands are found all over the body. The sweat produced by them is called "eccrine sweat" and it consists mostly of water but also contains small amounts of such substances as sodium chloride, lactic acid and urea. Apocrine glands (also called odor glands) are sweat glands associated with hair follicles which, in contrast to the eccrine glands, are only found in particular parts of the body like the armpits, areola mammae and genitals. The sweat secreted by them (apocrine sweat) is a milky type of sweat containing such substances as proteins, lipids, fatty acids, cholesterol, glucose and iron. Sweat itself does not have a particularly strong odor but it is converted into odoriferous substances by bacteria on the skin. In analyses of armpit and foot odors, such short chain fatty acids as pelargonic acid and caproic acid have been specifically detected in the former and isovaleric acid in the latter. These are the substances thought to cause body odor. 5.5.2. Functions and ingredients of deodorant

cosmetics

In consideration of the process by which body odor arises, deodorant cosmetics should have the following four functions. 5.5.2.7. Antiperspirantfunction Many products suppress the production of sweat through the use of pharmaceutical agents with a relatively strong astringent action such as zinc paraphenolsulfonate, citric acid, various aluminum and zirconium salts. Among such substances, aluminum compounds are in very common use, particularly aluminum hydroxychloride. Capable of being dissolved in water for liquid preparations, being incorporated as a powder in dispersion and aerosol types, and being dispersed through oily stick types, aluminum hydroxychloride has a very high degree of flexibility. 5.5.2.2. Antibacterial function for suppressing the proliferation of skin bacteria As it is bacteria on the skin which are responsible for body odor, antibacterial agents are used to suppress their proliferation to obtain a deodorant effect. Examples of antibacterial agents in common use are triclosan, benzalkonium chloride, benzethonium chloride, chlorhexidine hydrochloride, chlorhexidine gluconate and halocarbon. Some preparations use essential oils and extracts derived from crude drugs which have an antibacterial effect.

Cosmetics and skin 467

5.5.2.3. Deodorant function If metal salts are formed from short chain fatty acids, which cause body odor, their characteristic odor disappears. Applying this principle, if the short chain fatty acids which produce body odor are acted on by zinc oxide, a zinc salt of the short chain fatty acid is formed in accordance with the following reaction and the odor disappears. 2RCOOH + ZnO -^ (RC00)2Zn + H2O Plant extracts which contain a lot of such substances as flavonoids and chlorophyll may also be used for this purpose. 5.5.2.4. Masking function (unpleasant odor is covered up with a fragrance) Where the body odor is not very strong it can be masked with a perfume or eau de cologne, and there are types of cologne called deodorant cologne which achieve a stronger deodorant effect through the addition of the antibacterial agents mentioned above. Although four functions have been given for deodorant cosmetics, the sweat control and antibacterial functions should be focussed on in preparing formulae for actual products, in accordance with their intended purpose. The use of pharmaceutical agents should also be considered. It is also a good idea to enhance their deodorizing effect through the addition of odor removing ingredients and perfumes, to provide a masking effect and make them more suited to individual preferences. 5.5.3. Types of deodorant

cosmetics

5.5.3.1. Deodorant lotion Deodorant lotions are a liquid-form deodorant containing large amounts of ethyl alcohol so many of them give a very good cooling sensation and they are considered to be better at controlling sweat than other forms. Examples of this type are a spray type which uses no propellant (natural spray) and a roll-on type which is applied using a revolving ball. Typical formula 1. Roll-on type % Aluminium hydroxychloride Absolute ethyl alcohol Purified water 1,3-butylene glycol Benzalkonium chloride Polyoxyethylene(40) hydrogenated castor oil Water soluble thickening agent Perfume

10.0 60.0 25.3 3.0 0.2 0.5 1.0 q.s.

Manufacturing procedure Make a solution of the aluminum hydroxychloride, 1,3-butylene glycol, benzalkonium chloride and water soluble thickening agent in the purified water (water phase). Then make a solution of the surfactant and perfume in the absolute ethyl alcohol (alcohol phase), and add the alcohol phase to the water phase.

468 New cosmetic science Typical formula 2. Natural spray type Zinc paraphenol sulfonate Absolute ethyl alcohol Dimethylpoly siloxane Purified water Propylene glycol Triclosan Polyoxyethylene(40) hydrogenated castor oil Perfume

% 2.0 74.0 13.0 7.4 3.0 0.1 0.5 q.s.

Manufacturing procedure Dissolve the zinc paraphenol sulfonate and propylene glycol in the purified water (water phase). Dissolve the other ingredients in the absolute ethyl alcohol (alcohol phase), mix this with the water phase and filter. 5.5.3.2. Deodorant powder There are two types of deodorant powder, one of which is simply a mixture of powders, and the other a powder cake which is made by molding powders in the same way as for compact foundations. Typical formula. Pressed powder % 5.0 5.0 87.0 3.0 q.s.

Aluminum hydroxychloride Zinc oxide (zinc white) Talc Liquid paraffin Perfume

Manufacturing procedure After mixing the powders thoroughly together, dissolve the perfume in the liquid paraffin and add this to the mixture of powders as a uniform spray. Grind the powder mixture and mold by compression molding. 5.5.3.3. Deodorant spray Deodorant spray is an aerosol form of deodorant using liquefied gas as the propellant. There are two types: the wet type (toilet water type), and the dry type (powder type). The latter is usually called powder spray. On use, the toilet water type has the same feeling as a deodorant lotion whereas the powder type has a very refreshing feeling, a special feature of this type. Liquefied petroleum gas (LPG) is one of the major propellants used. As chlorofluorocarbons are now known to destroy the ozone layer, restraint is being exercised in their use. In the case of the powder spray type, it is necessary to take dispersibility (precipitation rate) and redispersibility of precipitated powder into account for the powders used in the formula. Typical formula 1. Lotion-type Deodorant solution formula

spray Zinc paraphenol sulfonate

% 2.0

Cosmetics and skin 469

Filling formula

Absolute ethyl alcohol Triclosan 1,3-buty lene glycol Isopropyl myristate Perfume Deodorant solution LPG

92.9 0.1 3.0 2.0 q.s. 50.0 50.0

Manufacturing procedure Dissolve the deodorant solution ingredients in the absolute ethyl alcohol and filter. Fill aerosol containers with the deodorant solution, attach the valves and fill them with LPG. Typical formula 2. Powder spray Deodorant solution

Filling formula

Aluminium hydroxychloride (fine powder) Silicic acid, anhydride (fine powder) Silicon-treated talc Zinc oxide (fine powder) Triclosan Isopropyl myristate Dimethylpolysiloxane Sorbitan fatty acid ester Perfume Deodorant solution LPG

% 30.0 15.0 15.0 5.0 0.1 21.9 10.0 3.0 q.s. 10.0 90.0

Manufacturing procedure Separately mix together the powder-form and liquid ingredients, pass the powder mixture through a sieve and filter the liquid mixture. Separately, put the powder and liquid mixtures into an aerosol container, attach the valve and fill the container with LPG. 5.5.3.4. Deodorant stick Deodorant stick is a stick-form deodorant made from oily ingredients, sweat suppressing substances and antibacterial agents. The stick form is said to have a sustained deodorant effect on account of its excellent adhesion. In terms of formulation there are two types: a non-transparent wax-based type; and a transparent soap-alcohol-based type. The former feels soft on the skin and the latter has a very refreshing feeling. Typical formula 1. Wax-based stick % Aluminium hydroxychloride Talc Solid paraffin wax Stearyl alcohol Liquid paraffin Cyclic dimethylpolysiloxane Sorbitan fatty acid ester Perfume

23.0 15.0 2.0 8.0 14.5 36.5 1.0 q.s.

470 New cosmetic science Manufacturing procedure Add the solid paraffin, stearyl alcohol and sorbitan fatty acid ester to the liquid paraffin, heating to melt the solid ingredients. Add the powders, make into a uniform dispersion using a Homomixer, pour into molds and cool to harden. Typical formula 2. Soap-alcohol-based stick Isopropyl myristate Sodium stearate Cetyl alcohol Propylene glycol Absolute ethyl alcohol Triclosan Purified water Perfume

% 12.0 10.0 3.0 25.0 48.9 0.1 1.0 q.s.

Manufacturing procedure Heat the ethyl alcohol and mix the sodium stearate into it. Continuing to heat, add the remaining ingredients, pour into molds and cool to harden.

5.6. Bleach and depilatories 5,6,L Bleach (or discolor) Bleaches in common use nowadays decompose melanin granules by oxidizing them, using alkaline hydrogen peroxide, so they can be used to change the color of black hairs to brown or blonde. As a result, they are used just as much as depilatories these days to make hair on the arms and legs inconspicuous. As well as their main ingredient of hydrogen peroxide, bleaches also contain oils, surfactants and bleaching promoters (ammonium persulfate and other persulfate salts). Bleaches contain strongly alkaline oxidizing agents, so care must be taken when using them. A problem with bleaches is that they easily damage hair by oxidizing keratin, its main constituent. The oxidation mainly occurs at the cystine bonds and other amino acid residues are also slightly oxidized. 5,6.2,

Depilatories

Depilatories are used to remove hair from the armpits, as well as from the legs and arms. Depilatories available on the market can be broadly divided into two types: those which physically remove hair; and those that do it by chemical means. These days, the former are referred to as hair removing products and the latter as dehairing products. The term of anagen for different parts of the body varies: for the forearm it is approximately 2 months while for the lower leg, about 3.7 months. The rate of growth also varies: for the armpits it is 0.3-0.42 mm per day, and 0.21-0.23 mm per day for the shins.

Cosmetics and skin 471 The effect of using hair removing products which remove hairs up to the hair root can thus be expected to last for one or more months, and dehairing products which remove hairs protruding above the skin surface, from a few weeks to a few months. However, as the hair cycle varies between different clumps of hair even on the same part of the body, it is actually necessary to use them every 2-3 weeks. 5.6.2.1. Hair removing products Hair removing products currently available on the market comprise those which involve spreading heated solubilized wax on the skin to envelop the hairs and then removing them together with the wax once it has cooled and solidified, those which involve spreading a thin layer of a tacky syrup like gel on the skin, tightly applying non-woven fabric and then removing this to pull out the hairs, and those which use strongly adhesive tape to pull out hair. They all require a certain degree of skill. As hair removing products pull out hairs right down to the root their period of effectiveness (the period until the hair grows again) is far longer than that of dehairing products. However, if the hairs to be removed have been bleached, they may break off before the root. The wax type is best for removing the thick hairs in the armpit while the gel type and the adhesive sheet type are good enough and convenient for the fine hairs on the legs. As the adhesive sheet-type can damage the skin, its repeated use on the same part of the body should be avoided. Typical formula. Wax type Rhodine Beeswax Solid paraffin Petrolatum Antioxidant

% 48.0 25.0 17.0 10.0 q.s.

Manufacturing procedure Make a solution of all of the ingredients by heating them together, pour into containers and cool to solidify. 5.6.2.2. Dehairing products As dehairing products remove unwanted hair by chemical means, there is none of the pain of hair removing products and no need for heating, as in the case of the wax type, so they are currently the most widely used type of depilatory. Dehairing products act by breaking the cystine bonds (disulfide bonds) in keratin, of which hair is composed, through their reduction. C H-CH2-S-S-CH2- C H Reduction ^ H-CH2-SH HS-CH^-C H In order to make this reaction take place as quickly and effectively it is necessary to keep the conditions alkaline with a pH of 11-13, to make the hairs swell.

472 New cosmetic science

Examples of reducing agents used are inorganic ones like strontium sulfide, sodium sulfide and calcium sulfide, and thioglycolic acid salts as the organic ones. As the inorganic reducing agents have an unpleasant smell and irritate the skin greatly, they are currently hardly used. Examples of thioglycolic acid salts used are calcium, sodium, lithium, magnesium and strontium thioglycolate. The ones in most common use are calcium and sodium thioglycolate. Thioglycolic acid salts have relatively little unpleasant smell so this can easily be masked with perfume and irritation to the skin is slight. They are strongly alkaline and become inactive when they absorb oxygen, so it is necessary to take care to select raw materials which will not be easily hydrolyzed and to consider the corrodibility of containers when making them. Dehairing products should be able to remove hairs 5-8 min after their application but this is affected by the concentration and pH of the thioglycolic acid salt. As a guide, the concentration should be at least 4% and the pH at least 12. As they work chemically, inflammation may be caused in some people so it is very important to give customers adequate instruction on their use. The products come in paste form, cream form and aerosol form. The cream and paste forms are best for under the armpits and other parts where very close contact is required. The aerosol form is best for application to wide areas. Details of the main ingredients and promoters used in dehairing products are given below. (1) Calcium thioglycolate (HSCH2COO)2Ca. Calcium thioglycolate is a white crystalline powder with a faint sulfide smell. Its solubility in water is 7% at room temperature and 27% at 95°C. It is alkaline in aqueous solution but when used, its pH is increased to around 12 by adding calcium hydroxide. Its product concentration is 2-10%. (2) Hair removal promoters. In some products, agents like urea, which swells and modifies hair protein, and organic amines like guanidine, are employed to enable the dehairing product to work more effectively, so that the hair can be removed in a shorter time. Typical formula 1. Cream type Calcium thioglycolate Cetyl alcohol Petrolatum Liquid paraffin Polyoxyethylene oleyl alcohol ether Polyoxyethylene stearyl alcohol ether Purified water Perfume

% 4.0 6.0 15.0 10.0 4.0 2.0 59.0 qs.

Manufacturing procedure Add the calcium thioglycolate to the purified water, heat to solubilize and keep at 65°C (water phase). Make a mixture of the other ingredients, heat to melt, disperse ingredients and keep at 65°C (oil phase). Add the oil phase to the water phase and make into a uniform emulsion in a Homomixer. Afterwards, stirring, cool to 35°C.

Cosmetics and skin 473

Typical formula 2. Aerosol type Purified water Dipropylene glycol Thioglycolic acid Sodium hydroxide Polyoxyethylene cetyl alcohol ether Liquid paraffin Perfume LPG Dimethyl ether

% 66.5 10.0 6.0 4.5 3.0 2.0 q.s. 6.0 2.0

Manufacturing procedure Add the thioglycolic acid to the purified water to make the water phase; then make a solution of the poly oxy ethylene cetyl alcohol ether, liquid paraffin and perfume at 70°C (oil phase). Add the oil phase to the water phase and after stirring, add the sodium hydroxide. Continue stirring and cool to 35°C to finish making the dehairing solution. Inject the dehairing solution into aerosol containers and add the propellants, LPG and dimethyl ether.

5.7. Bath preparations 5,7.1. History and purposes of bath preparations Since long ago, people have used hot springs for health and to treat disease. As hot springs are usually connected with volcanic activity they are most numerous in relatively young volcanic areas. The large numbers of hot springs in countries like Japan, Italy, New Zealand, Hungary, Germany, France and the United States (California) are located in such volcanic areas but there are also many hot springs in areas where no volcanic activity is known. The properties of hot springs vary depending on the minerals dissolved in their waters and, similarly, their effect on the human body also varies. Some make the skin beautiful or are beneficial for children, while others are good for bruises, stress relief and recovering from fatigue. Some of the many names applied to hot springs in Japan to indicate their properties are basic spring (typical low irritant hot spring in which the solid and free carbonate content is less than 1000 mg per kg of water), sodium bicarbonate spring, salt spring, sulfate spring, Glauber's Salt spring and gypsum spring. Containing such a wide variety of minerals, hot springs are effective against many different complaints. Ways have been devised for simply reproducing hot springs with beneficial effects in the home. The earliest ones involved drying hot spring constituents to make powders or making crystals from them (known as "hot spring flowers" in Japan). The later development of home-use "hot spring" preparations based on inorganic salts marked the beginning of products known as bath preparations in Japan and Europe. Bath preparations come in many different forms. For example, there are dispersions, granules, tablets, soft capsules and liquids.

474 New cosmetic science

To prevent tablets and soft capsules from being consumed in error, there is a regulation stating that their diameter must be at least 2 cm. The functions of bath preparations are as follows: (1) Give the bath a color and perfume in order to relax and refresh the mind. (2) Using the active ingredients of hot springs and pharmaceutical agents, keep the body warm, stimulate the circulation, relieve fatigue and improve the condition of the skin. (3) Cleanse the skin. Bath preparations are made to have a combination of these functions. A great many products have functions (1) and (2), and nowadays these are most common. Preparations with function (3) are called bubble bath. They are dissolved in the bath and worked into a lather before getting into the bath. The use of bubble bath is very common in Europe and the United States. 5.7.2. Types and functions of bath preparations 5.7.2.1. Bath preparations containing inorganic salts The preparations contain the inorganic salts found in hot spring water and then color and perfume are added. They are very soluble in hot water. The active ingredients of hot springs used in bath preparations are sodium and chloride, potassium chloride, sodium sulfate and magnesium sulfate to warm the body and stimulate the circulation, and sodium bicarbonate, sodium sesquicarbonate, sodium carbonate and potassium carbonate to cleanse the skin. Products come in the form of powders, granules and tablets but there are also effervescent bath salts which produces carbon dioxide bubbles when put in the bath water. Some of the ingredients are sodium bicarbonate, sodium sesquicarbonate and sodium carbonate. Crystals of such organic acids as succinic acid, tartaric acid and malic acid are also included. In addition, such hygroscopic agents as sodium sulfate and starch are added to enhance stability during storage. Typical formula 1 Powder type Sodium sulfate Sodium bicarbonate Color Perfume

% 50.0 50.0 q.s. q.s.

Manufacturing procedure Make a uniform mixture of the above ingredients. Typical formula 2. Granule type Sodium sulfate Sodium bicarbonate Sodium carboxymethylcellulose Color Perfume

% 50.0 49.0 10 q.s. q.s.

Cosmetics and skin 475 Manufacturing procedure Add an appropriate amount of water to the above ingredients and make into a uniform mixture. Extrude as granules, dry and sieve. Typical formula 3. Tablet type Sodium sulfate Sodium bicarbonate Sodium carbonate Succinic acid Lubricant Color Perfume

% 45.0 15.0 8.0 22.0 q.s. q.s. q.s.

Manufacturing procedure Make the above ingredients into a uniform mixture and form into round or square tablets using a tabletting machine. 5.7.2.2. Bath preparations containing medicinal plants These bath preparations include those in which dried medicinal plants are cut or ground up and packed into a cloth or non-woven fabric bag, and liquid products containing plant extracts extracted using solvents and inorganic salts, to which extracts dried by spray drying or other means are added. Some of the medicinal plants used are fennel, Scutellaria root, phellodendron bark, camomile, magnolia bark, fermented rice extract, peony root, houttuynia herb, Japanese iris, ginger, cnikium rhizome, citrus unshiu peel, capsicum, angelica root, ginseng, citron, mug wort, aloe and sapashnikovia root, Mentha herb. These plant substances are added for the body warming, circulation stimulation, anti-inflammatory, sedative, pain relieving, antibacterial and cleansing effects of the essential oils, tannin, azulene and various other substances contained in them. 5.7.2.3. Bath oils Bath oils consist mainly of liquid animal and plant oils, hydrocarbons, higher alcohols and ester oils. They are used to supply oil to the skin in order to keep it looking beautiful by preventing the evaporation of moisture, and making it soft and smooth. Bath oils designed mainly to give pleasure through their scent are sometimes called bath cologne or bath perfume. Bath oils can be classified as follows depending on their state (solution, dispersion, etc.) after adding to the bath: (1) floating type (oil droplets float on the surface) (2) spreading type (oil film spreads over the surface) (3) dispersion type (oil forms dispersion of very fine particles in the bath water) (4) milky type (oil forms a white cloudy dispersion in the bath water) No. (4), the milky type, gives the skin a non-sticky, smooth feeling which is much liked by the Japanese. The milky type consists of oils and surfactants and may be made into a liquid product just in this form.

476 New cosmetic science These days, the milky type comes in soft capsule form. Some of the advantages of using capsules are that there is just the right amount for one use in a capsule, capsules are compact, their transparent gelatin material gives an attractive appearance, can be colored and has a humectant action. As for the pharmaceutical products, the base material used to make the soft capsules consists of gelatin, glycerin and water. When they are put in the hot bath water, the gelatin capsule swells and dissolves, and the contents form a white cloudy dispersion. Typical formula. Milky type (capsule type) (a) Capsule contents

(b) Capsule

Liquid paraffin Squalane Macadamia nut oil Sorbitan oleate POE oleyl ether Perfume Water Gelatin Water Glycerin

%

60.0 10.0 10.0 5.0 10.0 4.0 1.0 41.0 41.0 18.0

Manufacturing procedure Make a uniform solution of the ingredients for (a). Make a uniform solution of the ingredients for (b) at 70°C, de-air and reduce temperature to 60°C. Keep at this temperature. Make the gelatin into sheets and then capsules. Roll the gelatin into a sheet of about 1 mm in thickness. Put the sheet into the cylindrical former of a rotary-type fully automatic capsule molding machine to form the capsules, using rotation in both directions. At the same time, pump the capsule contents into the capsules. Finish the molding of the capsule when the stipulated amount of the contents is inside it. This is done by sealing the capsule using the pressure of molding and applying heat to the gelatin sheet at the required temperature. To make the finished product, the capsules are dried gradually over a period of 3-7 days until their moisture content is 10% or less. 5.7.2.4. Bubble bath. Bubble bath is a product arising from bathing habits in Europe and the United States where the water tends to be very hard making it difficult to obtain a lather with soap. It is put into the bath tub and worked up into a mass of bubbles filling the whole bath by running in hot water vigorously from the faucets. Its main purposes are cleansing and softening hard water and people enjoy using it because of the copious amount of bubbles and perfume. Though it is widely used in Europe and the United States, it is hardly used at all in Japan because of the difference in bathing habits. Bubble bath comes in powder, granule, solid, gel and liquid forms. Raw materials used are those which have high foaming and cleansing capabilities even in hard water. The main ones are such anionic surfactants as alkyl sulfate esters and alkyl ether sulfate esters. Others include such non-ionic surfactants as polyoxyethylene alkyl ether and fatty acid alkanol amides and imidazoline-type amphoteric surfactants.

Cosmetics and skin

All

Examples of the powder and liquid types are given below. Typical formula 1. Powder type 70

Sodium lauryl sulfate Sodium sulfate Silicic anhydride Titanium oxide Tri-sodium edetate Color Perfume

40.0 44.0 10.0 5.0 1.0 q.s. q.s.

Manufacturing procedure Make the above ingredients into a uniform mixture Typical formula 2. Liquid type Sodium lauryl sulfate Sodium polyoxyethylene lauryl ether sulfate Triethanol amine polyoxyethylene lauryl ether sulfate Diethanolamide laurate Ethylene glycol distearate Glycerin Tri-sodium edetate Water Color Perfume

% 6.0 15.0 10.0 3.0 3.0 5.0 1.0 57.0 q.s. q.s.

Manufacturing procedure Mix the above ingredients together to make a uniform solution.

5.8. Insect repellents The purpose of insect repellents is to prevent the user from being bitten by mosquitoes, sandflies and other insects. Some of the substances used to repel blood sucking insects like mosquitoes, lice, fleas and mites are dimethyl phthalate, 2-ethyl-l,3-hexanediol, bisbutylene tetrahydrofurfural, A^,A^-diethyl-m-toluamide. When such insect repelling agents are applied to the body, they evaporate and surround the body with their vapor. This vapor repels mosquitoes by paralyzing their carbon dioxide sense organs and disrupting their water vapor sense organs. Typical formula. Insect repellent spray Ethanol A^,A^-diethyl-m-toluamide Perfume LPG (propellant)

%

49.5 5.5 q.s. 45.0

478 New cosmetic science

In Japan's Pharmaceutical Affairs Law, the upper limit on the inclusion of N^Ndiethyl-m-toluamide is 10%.

References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.

Ferguson, R. H, Rosevear, R B., Stillman, R. C : Ind. Eng. Chem., 35, 1005 (1943). McBain, J. W., Ross, S.: Oil and Soap, 24, 97 (1944). Ogino: J. Jpn. Oil Chem. Soc, 13, 804 (1964). Kamota, H., Ohata, Y., Aoki, K., Shishina, T.: J. Jpn. Oil Chem. Soc, 18, 804 (1969). Shimizu, K., Tsukada, H.: Fragrance J., 11 (1), 46-51 (1983). Food and Drug Administration ed.: Federal Register, 43 (166), 38206 (1978). German Industrial Norm. DIN, 67, 501 (1985). Australian Standard, 2604-1986. Japanese Cosmetic Industry Association Technical Data, No. 92, 109 (1991). Fukuda, M. et al.\ Nishi Nihon J. Dermatol., 49, 88 (1987). Kaidbey, K. H., Barnes, A.: J. Am. Acad. Dermatol, 25, 262 (1991). Cole, C. A., Lowe, N. J. Shaath, N. A., eds.: Sunscreens, p. 395, Marcel Dekker, New York, 1990. Fukuda, M. et al\ J. Soc. Cosmet. Chem., 33, 9 (1982). Sellers, R. L., Carpenter, F. G.: Cosmetics and Toiletries, 107, 119 (1992). Tsuchiya et al: J. Soc. Cosmet. Chem., 22, (1)10 (1988).

6

Oral care cosmetics

Oral care cosmetics can be broadly divided into dentifrices: preparations for external use which clean the teeth and the area surrounding them, cleanse and refresh the inside of the mouth, prevent dental caries and periodontal disease and mouth fresheners, preparations taken internally to prevent nausea and other feelings of discomfort.

6.1. Dentifrices 6.LL

History of dentifrices

The first record of the use of toothpaste in the history of mankind dates back to 1550 BC in ancient Egypt. It consisted of a mixture of such substances as flint powder, green rust, green clay, frankincense and honey. In ancient Rome and Greece, it is thought that a toothpaste made from powdered deer horn, the ash of animal bones, powdered pumice stone and marble, honey and various kinds of medicinal herb was used and that the use of toothpastes similar to this continued until the Middle Ages. Toothpastes similar in materials, form and functions to modem toothpaste did not appear until the 18th century and afterwards. The first toothpaste to be put in a tube was Sheffield Toothpaste which appeared in the United States in 1850. In recent years, many advances have been made in dentistry and pharmacology and research has been done on fluorides and other pharmacological substances so that toothpaste is now more than something for just cleaning the teeth and mouth; by preventing dental caries and periodontal diseases, it has become essential for maintaining the oral cavity in a healthy condition. 6.1.2, Classification of oral cleansing products Oral cleansing products can be broadly divided into the categories of dentifrices which are used with a toothbrush and mouthwashes which are not. Dentifrices are further classified according to form, into the categories of tooth powder, moist (semi-kneaded) tooth powder, toothpaste, fluid-form toothpaste and liquidform dentifrice. Mouthwashes are classified by usage and form into the categories of directly used type, concentrated type and powder type (Tables 6.1 and 6.2).

479

480 New cosmetic science Table 6.1. Categories of oral cleansing product Usage

Category

Ingredients

Form

o

Moist tooth powder

Abrasive agent, wetting agent, foam- Abrasive around 70% ing agent, flavoring agent, pharmaceutical agent, etc.

Toothpaste

Abrasive agent, wetting agent, binder, Abrasive 60% or less foaming agent, flavoring agent, pharmaceutical agent, etc.

Fluid-form toothpaste

As above

Low viscosity type

Liquid-form dentifrice

Wetting agent, binder, foaming agent, flavoring agent, pharmaceutical agent, etc.

Contains no abrasive

Solvent, wetting agent, solubilizing agent, flavoring, pharmaceutical agent, etc.

Used as liquid. There are directly used, concentrated and powder types (refer to Table 6-2)

Dentifrice

1

1 ^ ^ Mouthwash

II 6.1.3.

i

Tooth powder

u O

Features

Abrasive agent, foaming agent, flavor- Abrasive at least 95% ing agent, pharmaceutical agent, etc.

liquefied

Dentifrices

6.1.3.1. Functions of dentifrices In Japan's Pharmaceutical Affairs Law, dentifrices are classified as "Cosmetics", which do not contain pharmaceutical agents, or "Quasi Drug Products", which do. Their stipulated indications and effects are shown in Table 6.3. Here, we can think of the indications and effects of cosmetic dentifrices as being the inherent functions of such dentifrices and are mainly associated with their cleaning action. In addition to having the basic functions of dentifrices, the quasi drug product dentifrices also play an active part in the prevention of dental caries and periodontal diseases through the chemical and pharmacological actions of the pharmaceutical agents that they contain.

Table 6.2. Different types of mouthwash Type Directly used type

Concentrated type

Powder type

Usage

Features

This type is used as it is.

Very convenient to use ; currently the most used type

The base solution is diluted with a fixed amount of water when used

Compact and light ; the mouth may be washed many times with the contents of one bottle.

The powder is dissolved in a fixed amount of water when used.

Easy to carry around

Oral care cosmetics 481 Table 6.3. Indications and effects of dentifrices Quasi-drug dentifrices

Cosmetic dentifrices (1) (2) (3) (4) (5) (6) (7)

Prevent dental caries Whiten teeth Remove plaque Clean inside of mouth Prevent halitosis Remove stains from teeth Prevent deposition of calculus

(1) (2) (3) (4) (5) (6) (7) (8) (9)

Whiten teeth Clean insider of mouth Refresh inside of mouth Prevent pyorrhea Prevent gingivitis Prevent deposition of calculus Prevent occurrence and aggravation of dental caries Prevent halitosis Remove tobacco stains Pharmaceutical agents must be incorporated for (4) to (9).

(1) Cleaning action. There are deposits of many different kinds of substances in the oral cavity (Table 6.4). Among them, the bacteria containing deposit, plaque, is a cause of dental caries, periodontal disease and halitosis. If it is calcified through the action of inorganic substances in the saliva, a very hard deposit of calculus will form on the teeth. Further, certain substances in the food and tobacco can stain the teeth causing them to lose their original attractive color. Although it is difficult to remove such deposits completely through the mechanical cleaning action of a toothbrush, they are removed very effectively through the actions of abrasives and foaming agents. (2) Prevention of dental caries. According to Keyes theory^), which is the most widely accepted, food (S) (especially sugar), tooth susceptibility (H-T) and tooth decay causing bacteria (M) are the 3 principal factors in the development of dental caries (C) (Fig. 6.1). In this process, tooth decay causing Streptococcus mutans and other streptococcus species, convert the sugar into insoluble, tacky polysaccharides and these polysaccharides Table 6.4. Oral cavity deposits Teeth deposits 1 ) Plaque 2 ) Calculus 3 ) Staining substances ( a ) From external sources ® In food (2) In tobacco (3) Metallic substances ( b ) From internal sources ® Decomposition products of diseased pulp tissue (2) Drug-derived substances (3) Substances arising from hypoplasia of the teeth Deposits on oral mucosa 1) Deposits on the gums and buccal mucosa 2 ) Fur (on tongue)

482

New cosmetic science

M : microflora S : substrate (diet) H-T : host and teeth C : caries

Fig. 6.1. Three factors in dental caries according to Keyes.

adhere to the surface of the teeth as a cluster which also includes the Streptococcus mutans and other oral bacteria. This is known as plaque. The Streptococcus mutans and other acid-producing bacteria in it produce acid from the sugar which dissolves the inorganic constituents of the teeth (decalcification) causing dental caries. As it is known that the extent of decalcification is governed by the degree of resistance teeth have to acid, possible ways of preventing dental caries are (1) cut down on sugar, (2) remove plaque on the surface of teeth and (3) strengthen the teeth's resistance to acid attack. As we mentioned previously, although plaque is removed by the basic cleaning action of dentifrices, its formation can be more actively suppressed by incorporating ingredients which prevent the proliferation of plaque-forming bacteria and break down the polysaccharides which cause bacteria to adhere to the tooth surface. Further, fluorides (NaF, SnF2, Na2FP03) make the teeth stronger. They do this by acting on the tooth constituent hydroxyapatite (Caio(P04)6(OH)2) to produce fluoroapatite (Caio(P04)6F2) which increases the acid resistance of the teeth and promotes recalcification (decalcified constituents recrystallize to form tooth substance). In addition, we know that dentifrices containing fluoride are much superior to dentifrices having only a cleaning function in preventing dental caries. (3) Prevention of periodontal disease. Periodontal disease signifies gingivitis, pyorrhea and other diseases of the periodontal tissue and arises from such general causes as nutritional imbalances, high blood pressure and diabetes and such local ones as oral cavity deposits, and tooth malalignment. As well as being a cause of dental caries, plaque is also a cause of periodontal disease: the endotoxin secretions of bacteria in accumulations of plaque at the junction of the teeth and gums will cause inflammation in the gums. The area of inflammation will become red and swollen with the dilation of blood vessels resulting in the formation of periodontal pockets (gaps) between the teeth and gums facilitating the accumulation of plaque and causing a rapid worsening of the inflammation and destruction of the periodontal tissue. In order to prevent such periodontal disease, it is of greatest importance to remove plaque and the preventive effect of dentifrices against it can be enhanced through the use of ingredients to reduce inflammation, suppress the proliferation of bacteria and stimulate the circulation in the gums.

Oral care cosmetics

483

Table 6.5. Ingredients of dentifrices Ingredients

I Ingredient category

Abrasive

• • • •

Calcium carbonate Calcium phosphate, dibasic Silica Aluminium hydroxide, etc.

Effect • Action • Principal ingredient of dentifrice • Remove dirt without scratching tooth surface

the

• Glycerin • Sorbitol, etc.

• Give moistness and plasticity (cream form) to the powders in the dentifrice

• Sodium lauryl sulfate, etc.

• Disperse the dentifrice throughout the mouth and clean away the dirt in the mouth

• Sodium carboxymethyl cellulose • Carrageenan, etc.

• Bind the powder and liquid ingredients together and give moldability

Flavoring agent

• • • •

• Adjust flavor • Make dentifrice more palatable by giving a refreshing taste and smell

Coloring agent

• Permitted colors

Humectant

Foaming agent

Binder

Preservative

Sodium saccharin Peppermint oil Spearmint oil Menthol, etc.

• Ethyl paraoxybenzoic acid • Butyl paraoxybenzoic acid, etc. • Purified water

Pharmaceutical agent

• Fluoride • Antibacterial agents • Anti-inflammatory agents, etc.

• Make the dentifrice more attractive looking • Prevent deterioration of dentifrice • Adjust viscosity and consistency of dentifrice • Prevent dental caries, pyorrhea and gingivitis, stop halitosis and enhance effectiveness in removing oral cavity contaminants

6.1.3.2. Ingredients of dentifrices The ingredients and their proportions vary depending on the type of dentifrice and the main ones are abrasives, humectants, foaming agents, binders, flavoring agents, coloring agents, preservatives and pharmaceutical agents (Table 6.5). (1) Abrasives. Abrasives are one of the main ingredients of dentifrices and mostly consist of powdered inorganic compounds. They remove substances adhering to the surface of the teeth without scratching it and bring out their natural luster. One of the major conditions to be satisfied by an abrasive is hardness. As the hardness of the enamel on the tooth surface is 6-7 on the Moh's scale, the hardness of an abrasive should be 3 or less. For practical purposes, the particle size should be 20//m or less: if it is more than this, the dentifrice will feel rough and may damage the tooth surface and gums. Needle and rod-shaped particles must be avoided. Although many methods have been suggested for measuring the abrasiveness of abra-

484

New cosmetic science

sive powders and abrasives incorporated in dentifrices, the radioactive dentin abrasion method^) is the most widely accepted in the world today. In this method, an extracted human tooth is irradiated to convert the ^^P in its dentine to ^^P. The tooth is then put into an abrasion testing machine together with an abrasive or a dentifrice and the abrasion of 32p is measured using a radioactivity counter. Using this method, if the abrasiveness of calcium pyrophosphate is taken as 100, a suitable value for the abrasiveness of an abrasive is 250 or less. Regarding other conditions, the pH of abrasives should range from weakly acidic to weakly alkaline and they should be white powders which are insoluble in water, flavorless and odorless. Needless to say, thorough consideration must be given to toxicity and other aspects of their safety. The following are examples of widely used abrasives which satisfy these conditions. (1) Calcium carbonate (CaCOj). Calcium carbonate is a cheaply available abrasive which has been used in dentifrices for a very long time. Its abrasiveness is generally higher than that of calcium phosphate. There are two types - a heavy and a precipitated type. The raw material for the former is limestone and for the latter calcium hydroxide. (2) Calcium phosphate, dibasic; calcium phosphate, dibasic, dihydrate (CaHP04, CaHPO4 '2H2O). There is a dihydrate form and an anhydride form. As the anhydride form is harder than the dihydrate form, it is not often used by itself. The dihydrate form has a mild abrasive effect and feels good on use. It is neutral in pH and has good compatibility with other ingredients. However, when it is in a dentifrice for a long period of time, it loses its water of crystallization, changes to the anhydride form and makes the dentifrice go hard. For this reason a magnesium salt or other stabilizer is added. (3) Silica, silica hydrate (Si02, Si02'nH20). The main ingredient of the silica used in abrasives is high purity amorphous silicon dioxide and there are variety of different types whose properties vary with the method of production. Silica is very suitable for use in dentifrices containing fluoride because no insoluble salt is formed when it reacts with fluoride. As its refractive index is lower than that of other abrasives, silica can be used to make clear gel-form dentifrices. (4) Aluminum hydroxide (Al(OH)s). Although aluminum hydroxide is found in the natural state as aluminum ore, the substance used in dentifrices is synthesized from aluminate. It is used as an alternative to calcium phosphate, dibasic because it is cheaper. (5) Other abrasives. Examples of other abrasives are calcium pyrophosphate, insoluble sodium metaphosphate and magnesium carbonate; and alumina may also be used for special types. (2) Humectants. Humectants give the powders used in dentifrices a paste-like consistency and prevent them from hardening in the tube or in air. The main ones used are polyhydric alcohols like glycerin, sorbit solution (highly concentrated aqueous solution of sorbitol), propylene glycol and polyethylene glycol. (3) Foaming agents. The functions of foaming agents are to disperse the dentifrice

Oral care cosmetics 485

throughout the oral cavity in order to enhance the cleaning effect and, acting as a surfactant, clean away the dirt inside it. Also, by means of their volume of foam, they give a feeling of thickness and satisfaction. Surfactants having excellent foaming, dispersion, suspension, permeation, cleansing and hard water resistance qualities as well as no toxicity or irritation, are selected for foaming agents. Because, they go into the mouth, attention is also paid to taste and smell. The one most frequently used at present is sodium lauryl sulfate: other examples are sodium lauroyl sarcosine, sodium alkylsulfo succinate, sodium cocomonoglyceride sulfonate and sucrose fatty acid esters. (4) Binders. Binders are used to prevent the separation of dentifrice powder and liquid ingredients and give an appropriate degree of viscoelasticity and form to the dentifrice. They also have an influence on the dispersion, foaming, rinsing and other qualities of the dentifrice in the oral cavity. The most widely used binder at present is sodium carboxy methylcellulose (CMC). CMC is physiologically inactive, it dissolves well in water, it very compatible with other ingredients, highly stable and relatively low in price. There are many types of CMC having a variety of different characteristics stemming from different degrees of hydroxy group substitution and polymerization, so it is necessary to select the most appropriate one for the purpose in mind. Other known cellulose derivatives include methylcellulose, hydroxyethylcellulose and hydroxypropylcellulose. Examples of other binders used are such polysaccharides as sodium alginate, carrageenan and xanthan gum; synthetic polymers like sodium polyacrylate and such inorganic clay minerals as bentonite and laponite. (5) Flavoring agents. Flavoring agents are used in dentifrices to make them easier to use. They get rid of the unpleasant smell and taste of the other raw materials and give dentifrices a cool, refreshing taste and cater to individual preferences. (1) Flavorings. Flavorings like peppermint oil, spearmint oil and L-menthol, which give a cool, refreshing taste, are used widely in dentifrices. Various other flavorings are used to cater to individual preferences. (2) Sweeteners. Sodium saccharin is widely used and the dentifrice humectants glycerin and sorbitol also impart sweetness. Needless to say, the sweetener used must not cause caries as this would defeat the object of the dentifrice. (6) Pharmaceutical agents. It is accepted that the pharmaceutical agents used in dentifrices help to prevent dental caries and periodontal disease (for further details refer to Oral Care Agents in the chapter entitled Cosmetics and Pharmaceutical Agents). 6.1.3.3. Typical dentifrice formulae Typical formula 1. Tooth powder Calcium carbonate Sodium lauryl sulfate Sodium saccharin Flavor Purified water

% 95.0 1.8 0.1 q.s. 3.1

486 New cosmetic science Typical formula 2. Moist tooth powder Calcium carbonate Glycerin Sodium lauryl sulfate Sodium saccharin Flavor Purified water

% 70.0 20.0 1.5 0.1 q.s. 8.4

Manufacturing procedure Dissolve the sodium saccharin in some of the purified water; then put the calcium carbonate, sodium lauryl sulfate, glycerin and remaining purified w^ater in a mixing machine and mix together. Add the sodium saccharin solution and flavor and mix together until uniform. Typical formula 3. Toothpaste Calcium phosphate, dibasic, dihydrate (CaHP04.2H20) Silica Glycerin Sodium carboxymethylcellulose Carrageenan Sodium lauryl sulfate Sodium saccharin Pharmaceutical agent Flavor Ethyl paraoxybenzoate Purified water

% 45.0 2.0 15.0 1.0 0.3 1.5 0.1 q.s. q.s. 0.01 35.09

Manufacturing procedure Dissolve the sodium saccharin in some of the purified water. Make a solution of the purified water, glycerin, sodium carboxymethylcellulose and carrageenan, mixing them together in a vacuum mixer; then mix in the calcium phosphate, dibasic, dihydrate; silica and sodium lauryl sulfate. Next, add the sodium saccharin solution, flavor and ethyl paraoxybenzoate, mixing until uniform. Reduce pressure and de-air. Care is necessary to ensure that the mixing and de-airing are carried out properly otherwise the solid and liquid ingredients will separate after some time. Typical formula 4. Toothpaste (gel form) Silica Sorbit solution Glycerin Sodium carboxymethylcellulose Sodium lauryl sulfate Sodium saccharin Flavor Ethyl paraoxybenzoate

% 20.0 55.0 10.0 1.5 1.8 0.05 q.s. 0.01

Oral care cosmetics 487 Coloring agent Purified water

qs. 11.64

Typical formula 5. Fluid-form toothpaste 70

Silica Propylene glycol Glycerin Sorbit solution Sodium polyacrylate Sodium lauryl sulfate Sodium saccharin Flavor Ethyl paraoxybenzoate Coloring agent Purified water Typical formula 6. Liquid-form dentifrice Ethanol Glycerin Sodium lauryl sulfate Polyoxyethylenepolyoxypropylene glycol Sodium saccharin Flavor Sodium benzoate Coloring agent Purified water

10.0 2.0 5.0 10.0 1.0 1.0 0.1 q.s. 0.01 q.s. 70.89 % 10.0 5.0 1.0 0.5 0.15 q.s. 0.1 q.s. 83.25

Manufacturing procedure Dissolve the glycerin, sodium lauryl sulfate and polyoxyethylene-polyoxypropylene glycol in the purified water; then dissolve the flavor in the ethanol and add this, mixing to dissolve. Dissolve the sodium saccharin, sodium benzoate and coloring agent in this and filter. 6.1.4.

Mouthwash

6.1.4.1. Functions and ingredients of mouthwash Mouthw^ash is also referred to as mouth rinse. Though it is similar in form to a liquidform dentifrice, it is not used with a toothbrush: an appropriate amount is put in the mouth to rinse it out and then discarded afterwards. There are directly used, concentrated and powder types although the directly used type is the most widely used at present (refer to Table 6.2). Mouthwash has a relatively short history and with changes in lifestyle and the recognition of the importance of oral hygiene and preventive dentistry, its use is rapidly increasing. The functions of mouthwash are to clean the inside of the mouth, prevent halitosis and refresh the mouth. Mouthwashes containing pharmaceutical agents are effective in pre-

488 New cosmetic science Table 6.6. Ingredients of mouthwashes Category Water Solvent Humectant

Solubilizer

Flavoring agent

Preservative Coloring agent pH adjuster

Ingredient

Effect • Action

Purified water

Adjustment of viscosity, tency, volume, etc.

Ethanol, etc.

Dissolution of flavoring agents, give refreshing feeling

Glycerin, etc.

Moisturizing of mouth, aid dissolution of flavoring agents

Polyoxyethylene-hydrogenated castor oil, polyoxyethylene-polyoxypropylene glycol, sodium lauryl sulfate, etc.

Solubilization of flavoring agents, cleaning inside of mouth

Sodium saccharin, Menthol, Peppermint oil, etc.

Give a cool, refreshing feeling, special flavor

Ethyl paraoxybenzoate. Sodium benzoate, etc.

Prevent product deterioration

Permitted colors, caramel, etc.

Color to give attractive appearance

Phosphoric acid salts, citric acid salts

pH adjustment

Pharmaceutical agent

consis-

Stop halitosis, prevent dental caries, periodontal diseases, etc.

venting dental caries and periodontal diseases. Although mouthwashes containing fluoride for the prevention of dental caries are readily available on the market in other countries, such mouthwashes are treated as pharmaceutical products in Japan. Some of the ingredients used in mouthwashes are ethanol and other solvents, humectants, solubilizers, flavoring agents, preservatives and pH regulators. In the powder type, sodium bicarbonate and other diluting agents are used in the place of liquid ingredients (Table 6.6). Typical formula 1. Directly used type Ethanol Glycerin Polyoxyethylene-hydrogenated castor oil Sodium saccharin Sodium benzoate Flavor Sodium phosphate, dibasic Coloring agent Purified water

% 15.0 10.0 2.0 0.15 0.05 q.s. 0.1 q.s. 72.7

Manufacturing procedure Dissolve the glycerin and polyoxyethylene-hydrogenated castor oil in the purified water. Dissolve the flavoring in the ethanol and add this, mixing to dissolve. Next, dissolve the

Oral care cosmetics 489 sodium saccharin, sodium benzoate, sodium phosphate, dibasic and coloring agent in this and filter. Typical formula 2. Concentrated

type

Isopropyl alcohol Sorbit solution Sodium lauryl sulfate Sodium saccharin Flavor Sodium benzoate Coloring agent Purified water

% 30.0 10.0 4.0 0.15 q.s. 0.15 q.s. 55.7

Typical formula 3. Powder type Sodium bicarbonate Silica Sodium saccharin Flavor Coloring agent

% 97.8 2.0 0.2 q.s. q.s.

6.2. Mouth freshener Mouth freshener is a preparation for internal use designed to prevent nausea and other feelings of discomfort. Under Japan's Pharmaceutical Affairs Law it is treated as a Quasi-Drug Product. Some of the forms it comes in are pills, bars, troches and liquids. The liquid form is packed in a squeeze or pump type container and is squirted into the mouth as a mist. There are also food products for freshening the mouth such as candies, chewing gum and mouth freshening sweets but they are clearly separated from mouth fresheners in legislation. The ingredients used to flavor mouth fresheners have a strong freshening effect and include such crude drugs as catechu, fennel, licorice, cinnamon and cloves, mint oil, fennel oil, D-camphor, L-menthol and chlorophyllin derivatives. Depending on the form of the mouth freshener, other diluting agents, flavoring agents and preservatives are also used. Typical formula 1. Liquid type Ethanol Glycerin Polyoxyethylene-hydrogenated castor oil L-menthol Sodium saccharin Chlorhexidine digluconate Flavor Purified water

% 40.0 10.0 1.0 0.5 0.05 0.02 q.s. 48.43

490 New cosmetic science

Manufacturing procedure Dissolve the glycerin and polyoxyethylene-hydrogenated castor oil in the purified water. Dissolve the L-menthol and flavor in the ethanol and add this, mixing to dissolve. Then dissolve the sodium saccharin and chlorhexidine digluconate in this mixture and filter.

References 1. Keyes, P. H.: Int. Dental J., 12, 443 (1962). 2. Grabbenstetter, R. J. et aL: J. Dental Res., 37, 1060 (1958).

Index amphoteric surfactants 131, 408 anagen 50 analysis of axillary odor 275 analysis of natural perfumes 108 angle of repose 181 animal base (perfume) 116 animal test alternative 216 anionic surfactant 129, 408 anthraquinone dyes 85 anti-acne agents 156 antibacterial agents 157-161 anticariogenic agents 160 antidandruff agents 157 antihistamines 155 antiiching agents 157 antiinflammatory agents 152,158,161 antimicrobial agents 201 antioxidants 142 antiperiodontitic agents 161 antiperspirants 159 antiplasmin agents 161 antipruritic agents 158 antiseborrheic agents 158 antitarta agents 162 apocrine gland 19 apparent density 181 applicator containers 241 arbutin 148,225 aroma chemicals 111 aromachology 102, 103 aromatherapy 103 ascorbic acid 150 association colloid 166 astringent lotion 332, 333 astringents 153, 162 atomic absorption spectrophotometry 272 atomic emission spectrophotometry 272 auto-oxidation mechanism 142 azo dyes 83

abrasives 483 achromatic color 72 acidic mucopolysaccharide 14 acidic rinses 411 acne 28 causes of acne 29 skin care for acne 31 types of acne 31 acne vulgaris 28 acrylonitrile butadiene styrene resin (ABS resin) 242 acrylonitrile styrene copolymer (AS resin) 242 acute toxicity 213 A^-acylamino acid salt 130 A^-acylglutamic acid salt 408 acylmethyl taurate 130, 408 adrenocortical hormone 155 aerosol 248 components of aerosol 249 concentrates 250 containers 251 manufacturing processes 254 principle of aerosol 248 propellants 249 regulations on aerosol 253 stability test 194 after shave lotion 366 after-sun care product 464 aldehyde base (perfume) 116 alkyl amidopropyl dimethylaminoacetic acid betaine 132 2-alkyl-A^-carboxymethyl A^-hydroxyethyl imidazolinium betaine 132 alkyl dimethylaminoacetic acid betaine 132 alkyl sulfate 130,408 alkyl trimethyl ammonium chloride 131 alkylether phosphate 130 allantoin 152, 161 allergenicity 211 alopecia areata 414 aluminum hydrochloride 159 aluminum (container) 243 ambergris 104 amino acid-based cleansing foam 327 amino acid gel emulsification 350 amino acid indicator 224 amino acids 152, 163 /7-aminobenzoate 142 ammonia 428

baby powder 377 bacteria 199 Bandrowski's base 436 basal cell 14, 17 basal layer 13, 15 base makeup 4,371 base note 117 basement membrane 15

491

492

Index

bath oil 475 bath preparations 4 7 3 ^ 7 5 bees wax 123 bentonite 402 benzalkonium chloride 131, 157, 159, 203 benzethonium chloride 157,159 benzophenone derivatives 142 binders 485 Bingham flow 184 black iron oxide 90 blackheads 31 bleach 470 blood flow stimulants 151, 162 blow forming 244 blow molding 244 blush-on products 388 body cosmetics 4, 446 body odor 466 body shampoo 453 main ingredients 455 type 455 borax 347 boron nitrite 96 brass (container) 243 broken hair 63 bubble bath 476 1,3-butylene glycol 136 butylhydroxyanisol (BHA) 145 cake-type foundation 381 calamine lotion 335 calcium thioglycolate 472 camellia oil 122 candelilla wax 123 capillary viscometer 185 caps 253 carboxyvinyl polymer 140 carminic acid 88 camauba wax 123 carotene 23 y^-carotene 87 carthamin 88 castor oil 122 castoreum 104 catagen 50 cationic surfactants 131 cell membrane complex 55 cepharanthene 151 ceresin 125 cericite 89 cerotic acid 347 cetyl 2-ethyl hexanoate 128 cetyl alcohol 126 challenge test of microorganisms cheek color 388 chlorofluorocarbons 250 chlorohexidine gluconate 204 chroma 73 chromatic color 72 chronic toxicity 214

206

chypre base (perfume) 115 CIE standard colorimetric system 74 citrus base (perfume) 115 civet 104 cleansing cream 349 cleansing foam 323 main ingredients 323 manufacturing method 324 types 325 cleansing lotion 333, 340 cleansing oil 367 cloud point 172 coagulation 177 coalescence 179 cochineal 88 cold cream 343 collagen 14,44 colloid 165 colloid mill 285 color 71,401 image 77 impression of color 77 naming methods 73 of bare skin 79 of lips 80 of skin 80 perception 71 color materials 81 color of coloring materials 72 classification 82 color rinse 434 color spray 433 color stick 432 color system 74 coloring agents 387, 401 coloring pigments 90 column chromatography 259 combination bar 453 comedo 30 compact containers 240 compact powder 376 compact rouge 389 compressed gas 250 compression molding 244 conditioning shampoo 410 conductance 25 cone-plate viscometer 187 contact angle 182 contamination by microorganisms 200 continuous saponification methods 449 cooling equipment 285 comeocyte desquamating agents 156-157 cortex 55 cortex cell 50 cosmetic containers appropriate materials of container 236 characteristics required by container 235 maintaining quality of contents 235 material safety of container 236 types of container 238

493

Index cosmetics classification of cosmetics 4 quality characteristics of cosmetics 5 development process of cosmetics 7 chemical changes of cosmetics 191 laws relating to cosmetics (Japan) 297 definition of cosmetic 3, 294 couplers 434 cream 341 main ingredients of cream 342 manufacturing method for cream 343 purposes and function of cream 341 types of cream 345 creaming 177 creep measurement 187 critical micelle concentration (CMC) 170 CTFA (Cosmetic, Toiletry and Fragrance Association) 200, 209 curler lotion 421 cuticle 54 cuticle coating agent 230 cuticle remover 403 cyclical temperature test 195 cysteines 428 cystine bonds 471 dandruff 157,410 causes of dandruff 158 database 316 delayed darkening 36 dentifrices 479 function of dentifrice 480 ingredients of dentifrice 483 types of dentifrice 479 deodorant 159 deodorant cosmetics 466 function of deodorant cosmetic 466 ingredients of deodorant cosmetic 466 types of deodorant cosmetic 467 deodorant lotion 467 deodorant powder 468 deodorant powder spray 227 deodorant soap 453 deodorant spray 468 deodorant stick 469 deoxy hemoglobin 21 depilatories 470-72 dermal papilla 49 dermatan sulfate 14 dermatoheliosis 37 dermis 14,44 dialkyl dimethyl ammonium chloride 131 dibutylhydroxy toluene 145 di-isostearyl malate 128 dilatancy 184 dilatantflow 184 diluted solution transmittance method 458 dimethyl ether 250 dimethylpolysiloxane 128 discolor 470

disinfectant 201 disper 283 disperse colloid 166 disperse system 165 dispersion equipment 283 dispersion medium 165 disperse phase 165 disulfide bond 427^28 DLVO theory 178 documentation 310 dopaquinone 23 double emulsion 175 Draize primary skin irritation test method dry skin 28 dry-oily skin 28 dual-use foundation 380 dye precursors 434 dyes 83

211

eau de cologne 439, 445 eau de parfum 439 eau de toilette 439 eccrine glands 18 elastin 14,44 electric perm 426 emollient cream 346 emollient lotion 339 emulsification 174 emulsification equipment 283 emulsion 174 preparation methods of emulsion 175 separation phenomena of emulsion 177 emulsion type lipstick 388 emulsion types 175 enamel remover 402 endocuticle 54 environment friendliness 247, 256 epicuticle 54 epidermis 13,44 eponychium 68 essence 354 main ingredient of essence 354 manufacturing method for essence 355 purposes and functions of essence 354 types of essence 355 ester saponification method 449 esters 127 estradiol 152, 155 estrogen 152 estron 156 ethyl alcohol 440 ethyleneoxide propyleneoxide block polymers ethynylestradiol 152, 155 eumelanin 52 exocuticle 54 expression of color 73 extender pigments 89 extracellular matrix 14 extrusion molding 244 eye brow 396

133

494

Index

eye irritation 213 eye liner 391 eye makeup 390, 398 eye makeup remover 398 eye shadow 395

glycosaminoglycan 14,44 glycyrrhizinic acid 161 good manufacmring practices (GMP) granular layer 13, 16 GRAS (generally recognized as safe) green base (perfume) 115 grinders 281 gyratory grinder 285

face cleansing 322 purposes and functions of face cleansing 323 face powder 375 false eyelashes 398 fats 122 FDA (Food & Drug Administration) 82 fibroblasts 14 fibronectin 14 filaggrin 16 filling machines 291 film formers 140,400 fish scale flake 94 flavoring agents 485 floral base (perfume) 114 flowability 181 fluid-form toothpaste 487 fluoride compounds 160, 482 foaming agents 484 foaming detergents 455 follicle hormone 155 foot odor 466 forced vibration cone-plate viscometer 187 Fougere base (perfume) 115 foundation 378 classification of foundation 379 colors of foundation 79 molding machine of foundation 289 fragrance 101 history of perfume 101 role of fragrance 101 classification of perfumery raw materials 103 fragrance compounds 111 fragrance products 4 types of fragrance product 439 fragrance strength 118 fragrant powder 439 freckles 225 fruity base 116 fungi 199 furrow 25 gallic acid esters 145 gas chromatography 260 gel 351 for cleansing and removing makeup 353 main ingredients of gel 351 manufacturing methods for gel 353 purposes and functions of gel 351 types of gel 353 general separation techniques of cosmetic analysis germicides 201 glass 243 glass forming method 244 glycerin 135, 152

258

200, 280 209

hair 47 amino acid composition of hair 56 analysis of hair 276 causes of damage to hair 64 causes of hair loss 414 chemical composition of hair 56 chemical bond in hair 58 color of hair 52 extensibility of hair 59 form of hair 51 generation of hair 47 hair damage 61 moisture absorption of hair 60 physical characteristics of hair 59 thickness of hair 51 types of hair 47 hair bleach 430, 436 hair blow 425 hair bulb 49 structure of hair bulb 49 hair care cosmetics 4, 406 hair cleansing cosmetics 406 hair coating lotion for split ends 425 hair color 430 classification of hair color 431 mechanism of hair color 431 types of hair color 432 hair cream 424 hair cycle 50 hair diameter index 52 hair foam 418 hair follicle 48 hair follicle stimulants 151 hair friction measuring instrument 189 hair gel 420 hair grooming cosmetics 418 hair growth promoters 413 type of hair growth promoters 414 active ingredients of hair growth promoters 415 methods of evaluating of hair growth promoters 416 hair liquid 422 hair matrix 49,415 hair mist 420 hair mousse® 418 hair oil 426 hair pack 411 hair removing products 471 hair root 48 structure of hair shaft 53 hair root activating agents 152

Index

495

hair shaft 48 hair spray 248, 420 hair stick 423 hair treatment 411 types of hair treatment 424 halocarban 157, 159 hand care products 464 hand cream 465 headspace gas chromatography 110 heat exchanger 286 hemoglobin 24 high performance Uquid chromatography (HPLC) high-density polyethylene 242 higher alcohols 126 higher fatty acid-based cleansing foams 325 higher fatty acids 125 hinokitiol 161 histidine 17 HLB (hydrophile-lipophile-balance) 167 HLB number 167 HLB temperature 169 HLB value 167 homeostasis 320 homogenizer 284 homomixer 284 hormones 155, 163 horny layer 13-15 hue 72 humectants 134, 152, 412, 484 hunter lab system 74 hyaluronic acid 14 hybrid fine powder 97 hydrauric hair friction force meter 189 hydrocarbons 124 hydrophilic group 167 hydrophobic group 167

Kelvin's law 179 keratin 15,47 keratinization 15,28 keratinocyte 13 keratohyalin 13, 16 Keyestheory 481 kneader 285 kneading equipment 285 kojic acid 149 Kosmet 316 Krafft point 173 263

IFRA (International Fragrance Association) 119 IFSCC (International Federation of Societies of Cosmetic Chemists) 314 immediate darkening 35 impact forming 244 incomplete keratinization 28 infrared spectrophotometry 268 injection molding 244 inoculum test 206 inorganic pigment coated spherical organic powder 97 inorganic pigments 88 insect repellent 477 interface 167 interference color 93-94 iron oxides 90 isopropyl myristate 127 isostearic acid 126 isostearyl alcohol 127 jasmin base 114 jojoba oil 123 kaolin

90

l*a*b* system 76 lakes 85 lamellar granule 16 laminin 14 lanolin 124 lasting note (perfume) 117 lathering cream 364 lauricacid 125 liposome 180 lipstick 385 color of lipstick 80 lipstick molding machines 288 quality requirements for lipsticks 386 raw materials of lipstick 386 liquefied gas 249 liquefying cream 350 liquid crystal 171 liquid crystal emulsification 176 liquid face powder 377 liquid paraffin 124 liquid-form dentifrice 487 liver spots 225 loose powder 376 lotion 327 purposes and functions of lotion 327 main ingredients of lotion 328 manufacturing method for lotion 330 types of lotion 330 low density polyethylene 242 lunula 68 macadamia nut oil 122 machineless wave 427 makeup cosmetics 4, 78, 370 functions of makeup cosmetic 370 raw materials used in makeup cosmetic 371 types and forms of makeup cosmetic 371 male hormones 414 male pattern baldness 414 manicure preparations 398 mascara 393 mass spectrometry 270 massage cream 347 mast cell 14 maturing (perfume) 440 maximization test 211 medulla 56 melanin 22-23, 35, 148

496 melanin granule 52 melanin synthesis pathway 23 melanocyte 13, 22, 49, 52, 148 melanoid 21 melanosome 22 men's cologne 445 mesophase 171 metal forming methods 244 metal mold molding machine 288 metallic soap 146 p-methoxycinnamate 142 methylphenylpolysiloxane 128 methylpolysiloxane 128 mica 89,93 micelle 170 formation 170 microcrystalline wax 125 microemulsion 173,332 middle note (perfume) 117 milky lotion 335 ingredients of milky lotion 337 manufacturing method for milky lotion 338 purposes and functions of milky lotion 335 types of milky lotion 338 minimum-erythema dose (MED) 36, 457 moist tooth powder 486 moisture balance 321 moisturizing gel 353 moisturizing milky lotion 339 molding machines 288 molecular colloid 166 mouth freshener 489 mouthwash 487 function of mouthwash 487 ingredients of mouthwash 487 Muguetbase 114 multi-layer lotion 334 multiple emulsion 175 Muncell color system 74 musk 104 musking effect (function) 102 mutagenicity 214 myristic acid 126 nail function and physiology of nail 66 nail damage 68 physical characteristics of nail 68 structure and composition of nail 66 water content of nail 68 nail bed 67 nail cuticle 66 nail drier 404 nail enamel 399 quality requirements of nail enamel 399 main ingredients of nail enamel 400 nail guard 404 nail lunula 68 nail matrix 67 nail plate 66

Index nail polish 404 nail treatment 403 nail wall 68 narrow-mouth bottles 239 natural colors 86 natural moisturizing factor (NMF) 17, 134, 320 natural pearl essence 93 natural perfumes 104 manufacturing methods of natural perfume 104 natural polymer 139 natural surfactants 134 nature of olfaction 100 NDGA (nordihydroguaiaretic acid) 145 neat soap 449 negative replica 25 neutralization method (soap) 449 new functional pigments 96 Newtonian fluid 183 nitro cellulose 141 non-aqueous emulsification 176 nonionic surfactants 132-133,409 normal skin 28 nourishing agents 151 nuclear magnetic resonance (NMR) 268 number of residual nuclear clusters 223 nylon powder 95 2-octyldodecanol 127 2-octyldodecyl myristate 127 Ogive capsule molding machine 289 oil absorption 380 oil in water emulsion 175 oil rinses 411 oil-based foundation 382 oil-based kneaded rouge 389 oil-based lipstick 387 oils and fats 122 oily skin 28 olfactory gas chromatography 110 olfactory mechanism 100 olive oil 122 one-step shampoo 412 online information retrieval system 316 onychoschisis 68 opaque glass 243 optimum packaging 237 oral care agents 160 oral care cosmetics 4, 479 oral cavity deposits 481 oral deodorants 162 organic pigments 86 organic synthetic coloring agents 82 organically modified clay mineral gel emulsification technique 350 oriental base (perfume) 115 orifice viscometer 185 Ostwaldflow 184 Ostwald ripening 179 OAV emulsion foundation 383 OAV type medium cream 346

497

Index oxidation hair color 434 oxidizing agents 427-428 oxyhemoglobin 21 ozone layer 32 pack 357 main ingredients of pack 359 manufacturing methods for pack 359 purposes and functions of pack 357 types of pack 360 packaging machines 291 palmitic acid 126 pantothenic acid 155 pantothenic acid derivatives 152 paper sheet type face powder 377 paraben 201 paraffin 124 parallel-plate plastmeter 188 paraoxybenzoate 201 patch test 215 pebble mill 285 peel-off pack 360 pencil containers 241 penetrator 188 perfume 439 choosing a perfume 442 classification of perfume 441 keeping a perfume 442 manufacturing methods for perfumes 440 wearing perfume 442 perfume creation 116 perfume dosage 118 perfumed soap 439 perfumer 116 perlescent (nacreous) pigments 93 permanent hair color 431, 434 permanent waving lotion 426 types of permanent waving lotion 428 waving lotion 429 neutralizer 430 permanent waving mechanism 427 permitted colors 82 perspiration 18 components of perspiration 19 petrolatum 125 phaeomelanin 52 Pharmaceutical Affairs Law 4, 294 phase inversion temperature emulsification 176 photoacoustic spectrometry (PAS) 275 photoaging 37,39 photoallergenicity 37,212 photochromic pigment 97 photosensitivity 37 photosensitization 212 photo-stability test 192 phototoxicity 37,212 physiological and psychological effects of odors 102 placenta extract 152 plaque 481 plastic flow 184

plasticizer 401 plastics 241 forming methods of plastic 243 plate heat exchanger 286 point makeup 4, 379 polyethylene glycol 136 polyethylene powder 95 polyethylene terephthalate 243 polyethyleneterephthalate polymethylmethacrylate laminated powder 95 polyhydric alcohol ester type nonionic surfactants 133 polymer powder 94 polymeric surfactants 134 polymers 138 polymethylmethacrylate 95 polyoxyethylene alkyl ether sulfate 130, 408 polyoxyethylene type nonionic surfactants 132 polypropylene (PP) 242 polystyrene (PS) 242 polyvinyl alcohol (PVA) 140 polyvinyl chloride (PVC) 243 polyvinyl pyrrolidone (PVP) 141 pomade 423 porosity 181 potassium/lead glass 243 powder containers 240 powder mixing equipment 281 powder products 367 powdery foundation 379 p-phenylenediamine 435 preference (perfume) 118 preservatives 199,201 preshaving lotion 365 press and blow forming 244 pressed powder 375 pressing 244 pressure resistant containers 251 pressurized gases control law 253 prevention of dental caries 481 primary contamination 200 prohibited ingredients 299 promoters 456 propeller mixer 283 propylene glycol 135 proteoglycan 14 pseudoplastic flow 184 psychorheology 183 pyrrolidone carboxylic acid 17,152 quasi-drugs 3, 4, 294 quince seed gum 139 quinoline dyes 84 REAS (reasonably estimated as safe) 209 red iron oxide 90 reducing agent 427^28 5a-reductase 414,417 refrigerants 153 regulations concerning containers 302

498

Index

regulations on cosmetics in other countries 304 regulations on quasi-drug products 301 regulations relating to raw materials 298 replica analysis 25, 43 reproductive toxicity 214 required HLB 168 resins 400 reversed micelle 171 rheology 183 rheology measurement methods 184 ridge 25 RIFM (Research Institute for Fragrance Materials) 119,209 rinse 410 functions of rinse 411 ingredients of rinse 411 roles of olfaction 99 roller 285 rose base 114 rotating cylinder viscometer 186 rotating spindle viscometer 185 rouge 388 safety test 210 salicylic acid 157 salicylic acid derivatives 142 salting out 449 saponification method (soap) 448 scale up 197 scrapered surface heat exchanger 288 sebaceous gland 17 sebum 17 sebum secretion inhibitors 156 secondary contamination 200 semipermanent hair color 431, 433 sensitization 211 sequestering agents 146 setting lotion 421 shampoo 407 main ingredients of shampoo 407 shaving cosmetics 363 purposes and functions of shaving cosmetic types of shaving cosmetic 363 shaving cream 363 shaving foam 365 shaving soap 363 silicone gum 141 silicone oil 128 silicones 128 skin 13 absorption of skin 20 aging of skin 38-39,44 alleviation of skin roughness 220 analysis of skin 273 biological function of skin 19 colors of skin 21 pigmentation of skin 42 protection of skin 19 sagging of skin 42 sensory perception of skin 20

363

surface configuration of skin 44 thermoregulation of skin 20 skin blood flow 45 skin cancer 37 skin care agents 152 skin care cosmetics 4 purpose of skin care cosmetics 319 function of skin care cosmetics 320 role of skin care cosmetics 320 skin condition 24, 28 skin irritation 210 skin surface lipid 17, 30, 45 skin surface pattern 25 skin viscoelasticity meter 188 soap 129,446 manufacturing methods of soap 448 raw materials of soap 447 types of soap 450 soda glass 243 sodium 2-pyrrolidone-5-carboxylate 136 sodium carboxymethyl cellulose 140 sodium edetate 146 sodium hyaluronate 137 sodium lactate 136 softening lotion 330 solid perfume 439 solubilization 173 solvents 401 sorbitol 136 special accelerated stability test 195 special aerosol containers 256 specific surface area 180 specific volume 180 spectral reflection curve 72 spectral transmission curve 72 SPF analyzer 458 spice base (perfume) 116 spinous cell 13 spinous layer 13, 15 split hair 63-64 split hair coating lotion 425 squalane 125 SSB (skin surface biopsy) 223 stabilizers 456 stainless steel (container) 243 stearic acid 126 stearyl alcohol 127 steel (container) 243 stick container 240 Stoke's law 177 Streptococcus mutans 160 stress test of product 195 subacute toxicity 214 subcutaneous adipose tissue 45 subcutaneous fat 15 sulfur 157 sun protection factor (SPF) 142, 457 suntan 36 sunburn 35 suncare products 457

499

Index types of suncare product 460 sunscreen cosmetics 460 suntan cosmetics 461 surface active agents 129,167 surface area of horny cell 28 surface modification 182 surfactant (D) phase emulsification suspending agents 401 sweat gland 18 sweat odor 466 Swertia extract 151 Syndet bar 453 synthetic mica 96 synthetic polymer 139

tyrosine

176

talc 90 talcum powder 378 tar cleansing agents 162 telogen 50 temperature and humidity combination test 195 temperature stability test 191 temporary hair color 432 tension in the scalp 415 testosterone 414 thickening agent 138 thin film transmittance method 458 thioglycolates 428 thixotropy 184 three attributes of color 72 tinctura capsici 151 tinctura zingiberis 151 titanium dioxide 92 titanium dioxide coated mica 93 tocopherol 145 toilet soap 450 tooth powder 485 toothpaste 486 top note (perfume) 117 toxicity 213 transepidermal water loss (TEWL) 27 transparent liquid shampoo 410 transparent soap 451 crystal structure of transparent soap 452 treatment lotion 425 trichlorocarbanilide 201 tricogram method 417 triphenylmethane dyes 84 tubular containers 239 turnover 15,44 types of hair styling preparation 418 types of nail care product 399 tyrosinase 23, 149

23,52

ultramarine 91 ultrasonic emulsifier 285 ultraviolet absorbents 142 ultraviolet light A 32, 37 ultraviolet light B 32 ultraviolet light C 32 underarm odor 466 urocanic acid 17 usage test 215 vacuum forming 244 validation 207 value 73 valves 252 vanishing cream 345 vasodilators 151 vesicle 180 visible light 32, 37, 70 vitamin A 153 vitamin A acid 38 vitamin B group 154 vitamin c group 150 vitamin D 154 vitamin E 151,154 vitamin H 155 vitamins 152-153, 162 water content of horny layer 25 water grease 420 water in oil emulsion 175 wax esters 122 wettability 182 white masking 97 white pigments 92 whiteheads 31 whitening agents 148 whitening cosmetics (effect) 225 wide-mouth botde 239 W/0 emulsion foundation 384 woody base (perfume) 115 wrinkle 37,40 xanthangum 139 xanthene dyes 84 X-ray diffractometry yeasts 199 yellow iron oxide zinc oxide

93

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