9 Hair shampoos FJ. Mottram and CE. Lees 9.1 INTRODUCTION Washing the hair and scalp has become a near-universal practice. The method of doing so varies depending on both geographic and economic factors. Shampoos assumed importance as a product category with the advent of synthetic detergents. These were developed in the 1930s, became widely used in laundry markets by the mid-1940s and appeared in a shampoo format during the 1950s. Shampoos are probably the most widely used hair products today; based on synthetic detergents they are relatively insensitive to water hardness, thus allowing for efficient rinsing since there are no scum residues. In the early days a shampoo could be defined as an effective cleansing agent for hair and scalp, but today the shampoo must do much more. It must leave the hair easy to comb, lustrous and controllable whilst being convenient and easy to use. 9.1.1 Requirements of a shampoo 1. To remove sebum (the secretion of the sebaceous glands) and atmospheric pollutants from the hair and scalp. 2. To remove the residues of previously applied hair treatments, e.g. polymeric constituents from styling lotions and hair sprays. 3. To deliver an optimum level of foam to satisfy the expectation of the user. 4. To leave the hair in a satisfactory condition after rinsing so that it can be combed easily both in the wet and dry state. 5. To perform as a vehicle for the deposition of beneficial materials onto the hair and scalp. 6. To be non-toxic and non-irritating to the hair and the scalp. 7. To be non-damaging to the tissues of the eye if inadvertently splashed. Butler, H. (ed), Poucher's Perfumes, Cosmetics and Soaps, 10th Edn., 289-306 © 2000 Kluwer Academic Publishers. Printed in Great Britain 9.1.2 Classification of shampoos Shampoos are usually classified according to function, e.g. anti-dandruff, medicated, 2-in-l shampoo, mild baby shampoo, basic beauty shampoo, premium conditioning shampoo. 9.2 THE ACTION OF SHAMPOO ON THE HAIR The original prime purpose of the shampoo is to cleanse the hair. The underlying science has been reported by Lawrence [1,2] and by Breuer , who recognized three basic components of hair soil: 1. Sebum, the oily secretion of the sebaceous glands. 2. Proteinaceous matter arising from the cell debris of the stratum corneum layers of the scalp, and the protein content of sweat. 3. Atmospheric pollutants and residues from other hair-care products. There is an extensive literature on the subject of sebum, much of it summarized in a review by Gershbein and Barburoa . They examine both the physicochemical and biological aspects of sebum. An example of the latter may be found in a paper by Kligman and Shelley  which deals with the physiology of the secretion. In order to gain an insight into the in-situ properties of sebum a number of studies were made, most noteworthy those of Curry and Golding . In the course of their investigations they reached the conclusion that the free fatty acids of sebum may well be linked to the protein surface of hair through calcium atoms. The same concept also emerges from the work of Koch et al.  and from a consideration of the nature of detergency by Davies and Rideal . Breuer  has studied the kinetics of the regreasing of freshly cleaned hair. He regards a representative composition of sebum to be as in Table 9.1. Squalene is a triterpene containing four unsaturated -C = C- bonds; its relative molecular mass is 410 and it is the biosynthetic precursor of lanesterol. Basically the above composition is not radically different from the artificial sebum used by Spangler  for his studies of the laundering of textiles. Among the methods used by Breuer to monitor the spreading of sebum was a sophisticated optical technique which measured changes in hair-fibre spacing as Table 9.1 Composition of sebum Component Cholesterol Fatty acids (free) Triglycerides Wax and wool-wax esters Squalene Sundry hydrocarbons % by weight 8.5 22.0 35.0 18.6 11.3 4.6 the sebum spread in a parallel assembly of hair fibres. He also established in other experiments that the rate of sebum spreading, when the hair had been dried in a current of hot air from an electric hair drier, was considerably greater than when the hair had been allowed to dry at room temperature. 9.2.1 The process of soil removal There are three types of soil to be dealt with. These are oily soil or sebum, soluble soils, and insoluble particulate soils. All three types of soil require to be wetted, thus the surface tension of the water is reduced by the shampoo surfactant allowing full contact with the soil's surface. Any soluble soil is then removed in the aqueous medium. Oily soil or sebum is removed by a process known as 'roll-up', i.e. the displacement of the soil by the detergent solution. Insoluble particulate soils tend to be removed by electrostatic repulsion between the soil and the hair fibre assisted by repulsion between the surfactant molecules adsorbed onto the hair fibre and those dissolved onto the soil. Breuer also considers the rheological properties of sebum to exert a strong influence upon soil removal, and it is conceivable that the phenomenon of myelenesis contributes to soil displacement, although less than in the case of textile laundering. Myelenesis can be observed (through a microscope), when a layer of lipid material, even material of low polarity such as fatty alcohols, is immersed in water. The lipid layer develops peninsular-like processes which penetrate into the aqueous medium. These appear to function like pipes, transporting the lipid progressively into the bulk water phase. In that region the former surface lipid coexists within the micelles of the detergent solution as co-micelles of detergent and lipid. The effect is best seen when the lipid is highly polar, e.g. in the phospholipids, lecithin and cephalin. The rate at which the lipid migrates into the aqueous phase is very temperature-dependent. Chan  proposes a third mechansim which is illustrated by Fig. 9.1. According to Chan the detergent micelles make contact with the lipid surface for a finite time during which they take up an increment of lipid. This is assimilated to form lipid-detergent co-micelles which detach and 'float away' into the bulk aqueous solution. It is felt that Chan may be expressing the process of myelenesis in different terms. In Fig. 9.1 the rectangular 'core' of diagrammatic micelles can be considered to represent the hydrocarbon domain created by the non-polar regions of the detergent molecules; the small circles represent the polar heads of these molecules. 9.2.3 Summary of cleansing Although detergency plays an important role in the cleaning of hair with shampoo, other factors must be considered. For example, gaps exist in our knowledge A Free detergent micelle • Lipid soil B Micelle contacts soil surface C Co-micelle (detergent and soil) floats away Fig. 9.1 The Chan 'float-away' cleaning mechanism. of the physicochemical nature of the ageing of sebum and how this is related to its rheological properties. We would also wish to know the extent to which captured particles of soil from the atmosphere modify the fluidity of sebum. One of the few attempts to describe the physical properties of sebum extant is that of Bore et al. , who employed thermal analytical techniques (differential thermal analysis, DTA). It is also important to be able to apportion the individual contributions of surface energy and surface rugosity to the rate at which hair is regreased. Another element of fundamental information which is not currently available to us attaches to the relative importance of tactile and visual factors in determining the perception of cleanliness of hair. 9.3 THE FOAMING OF SHAMPOOS The 'signal' to which the user responds when applying a shampoo is how quickly it builds up lather and how copious that lather is. This tends to colour the user's later impressions of the other performance characteristics of the shampoo. Three well-defined stages appear to be involved: the rapidity with which the foam is formed; the peak volume of the foam; and the consistency of the lather. A high-consistency foam is judged as being 'creamy'. It is not surprising, therefore, that the shampoo formulator needs to be able to measure the important foaming properties, even though the fundamental properties of a foam, e.g. interfacial tension and film modulus, do not form a reliable guide to the performance of the shampoo in practice. One version of a technique by Ross and Miles  to measure foaming properties is outlined below. A standard volume of shampoo solution is transferred to a tap-funnel. The solution in the funnel is run in a standard time into a large measuring cylinder which already contains a set volume of the solution, or merely the dilution water. The result of the stream of solution from the funnel impacting on the liquid in the cylinder is to generate a foam, the volume of which can be read directly. The procedure can be modified; for example, the cylinder may contain a suitable quantity of sebum-treated hair, or the gravity feed from the tap-funnel can be replaced by a pump. The Ross-Miles method, like some other methods for quantifying foam, usually ranks the foaming of shampoos in the same order as human judges do (users, panellists and hairdressers), but not invariably. Other methods of quantifying shampoo foaming capacity utilize propeller stirring or air injection to generate foam but are, in general, less reliable. The quantification of the consistency of foam (creaminess) by in-vitro laboratory techniques is less well provided for than the measurement of foam volume. However, an innovation by Hart and Degeorge  offers some promise. The principle of the method is that a high-consistency foam will take considerably longer to flow out via the stem (broad) of a powder funnel than a foam which is thin and dubbed as non-creamy. An ideal laboratory method for predicting the foaming power of shampoos would closely simulate the practical shampooing process. It would ensure that the foam was generated in a way similar to its formation on the head of the user. Similarly, the composition of the system in which the experimental foam is produced would be as similar as possible to that of the hairdressing situation in terms of materials present (hair, sebum, detergent, water). The temperature and humidity profile would also be modelled upon that met with in hairdressing practice. Perhaps the most important simulation would be that of the mechanics and dynamics of foam generation. Lather production in practical shampooing is not by cascading water, mechanical stirring or gas injection. It is in fact achieved by a process of compressing and shearing hair when it is saturated with shampoo solution. The foam produced by compression and shear is then modified by the practice of separating by finger action a particular mass of hair fibres and shampoo solution into smaller 'swatches' before recombining them. The engineering problems of designing a machine to meet the requirements described above are formidable, but not insurmountable. 9.4 SHAMPOO INGREDIENTS A shampoo is basically a solution of a detergent modified by additives to render it easier to apply and to safeguard against deterioration of the hair condition after the shampoo has been rinsed away. The following list classifies the materials of shampoo formulation; the subdivisions are not, however, mutually exclusive, e.g. viscosity modifiers can sometimes be used to stabilize or boost the foam and some opacifying agents can also improve foam quality. Likewise, amphoteric wetting agents can be used as the main detergent for specialist shampoos. They are also valued as hair-conditioning agents. • • • • • • • • Main detergents Foam boosters and stabilizers Opacifiers Hydrotopes Viscosity modifiers, including hydrocolloids and electrolytes Special additives for hair condition Special additives for scalp health, including antidandruff additives Sequestering agents. 9.4.1 Main detergents These are classified according to the way in which they ionize. Class 1: Anionics (a) Alkyl sulfates. Alkyl sulfates are produced by reacting a fatty alcohol with either chlorosulfonic acid or sulfur trioxide: Fatty + alcohol Chlorosulfonic acid Acid ester+Hydrochloric acid Acid ester+Sodium hydroxide Sodium alkyl sulfate R = Alkyl radical between C6 and C18 The acid ester formed requires neutralization to prevent it splitting to the original fatty alcohol and sulfuric acid. Sodium hydroxide, triethanolamine, monoethanolamine, ammonia and magnesium carbonate are commonly used bases. The carbon chain length of the original fatty alcohol affects solubility, foaming, detergency, and irritation potential of the resulting alkyl sulfate. (b) Alkyl ether sulfates. The manufacturing process for alkyl ether sulfates is similar to that for alkyl sulfates, but an ethoxylated fatty alcohol is used. The choice of base for neutralization is the same. The number of molecules of ethylene oxide in the resulting alkyl ether sulfate will affect foam, viscosity and mildness: Ethoxylated fatty+ Chlorosulfonic alcohol acid Acid ester+Hydrochloric acid Acid ester+ Sodium hydroxide Sodium alkyl ether sulfate n = 1 to 6 molecules of ethylene oxide (c) Sulfosuccinic acid mono and di-esters (sulfosuccinates). The mono-esters are very mild, with good foaming and detergent properties. The di-esters are superior for their wetting properties. Since they are sensitive to hydrolysis and are difficult to structure they tend to be used in conjunction with alkyl ether sulfates to produce mild shampoos. (d) Isothionates, taurides and sarcosinates. These are materials that have other interesting properties for the shampoo formulator, other than foam potential and detergency. Isothionates are exceptionally mild to skin and eyes, and are particularly tolerant to hard water. Donaldson and Messenger  have reported on the shampoo performance of both alkyl sulfates and alkyl ether sulfates. Class 2: Nonionics Materials in this class are not usually the major ingredient of a shampoo. They are important, however, as co-surfactants, rheology modifiers and solubilizers for insoluble components such as fragrance oils. (a) Fatty acid alkanolamides. These are formed by reacting a fatty acid with an alkanolamine, usually monoethanolamine or diethanolamine, to produce the corresponding alkanolamide: The major use is to modify rheology and to control foam consistency and quantity. They have largely been superceded by amphoterics in modern formulations. (b) Fatty amine oxides. These are obtained by reacting a tertiary amine with hydrogen peroxide. They have similar uses to the fatty acid alkanolamides. (c) Alkylpolyglucosides. These are formed by condensing fatty alcohols with starch. The ratio of starch to fatty alcohol can be varied such that foam properties and detergency can be controlled. It should be noted that when these materials are based on natural fatty acid the whole molecule is derived from natural, renewable sources. They have low toxicity, low irritation and are readily biodegradable. Class 3: Amphoterics These are defined as having both anionic and cationic charges in the hydrophilic head. The negative group is usually carboxylic and the positive group amino. In alkaline solutions the anionic function predominates whilst in acidic solutions the cationic function predominates. The isoelectric point lies between the two extremes at a position where the two charges are equal. The molecule at this point is called a zwitterion, and does not behave as a surfactant. Raising or lowering the pH allows the molecule to regain its surfactant properties. Amphoterics are compatible with all classes of surfactants. In combination with anionics, beneficial effects on foam and viscosity can be demonstrated and there is also a synergistic effect on mildness. (a) Imidazoline derivatives. The more commonly used dimidazoline derivatives are cocoamphocarboxyglycinate and cocoamphoacetate. They have a very low irritation potential and are utilized in baby or other mild shampoo systems. (b) Alkylamidobetaines and alkylbetaines. These materials are used as cosurfactants. They have the ability to modify rheology and foam character, whilst conferring mildness through their synergistic effects. Class 4: Cationics The surfactants in this group are normally incompatible with anionics, and, therefore, are unlikely to be used in shampoo systems. 9.4.2 Shampoo additives (a) Thickeners Sodium chloride is a suitable additive for a large number of formulae, achieving functionality by modifying the micelle structure. However, where a sulfosuccinate has been used as a primary detergent, polyethylene glycol diesters are much more effective. Hydrocolloids such as polyvinyl alcohol or cellulose derivatives can also be utilized, although incorporation of a cellulosic derivative requires care. Glucose esters can create difficulties with their rheological profile, but do enrich the foam characteristics and reduce irritation. (b) Pearlizers and opacifiers Opacifying materials give the shampoo a creamy appearance which appeals to consumers with dry or damaged hair. A pearlized effect can be created by glycol distearate, but this requires a hot process and inconsistencies are inevitable. It is more usual to use prepared pearl concentrates. Latex opacifiers do not have the sparkle of the pearlizers, but are used to obtain a flat opaque appearance. (c) Preservatives A wide variety of preservatives exist. Liquid preservatives may be easier to incorporate, but choice is governed by challenge testing and stability of the formulation. Kumanova  has reviewed these test methods in relation to shampoos. The isothiazolinones or parabens are frequently used, but it must be emphasized that reference should be made to the regulatory status for permitted concentrations. (d) pH modifiers The isoionoic point for the hair fibre lies between pH 5.6 and 6.2. It is advisable to balance the pH of the formulation to within this range. Citric acid is typically used to achieve this. 9.4.3 Functional additives Functional additives are those which promote good condition of the hair. Hair in good condition is easy to comb both in wet and dry state. The dried hair should be free from 'flyaway', and be lustrous and manageable. As specific hair needs are better understood, ingredients can be tailored to deliver specific attributes. It is however incumbent on the formulator to substantiate the desired product claims, and to ensure that patents are not infringed. Listed below are some of the newer materials found in shampoos: • • • • • • Polyquaterniums Silicone additives Proteins and amino acids Ceramides Panthenol Glutamic acid derivatives. (a) Water-soluble polyquaterniums: mechanics of deposition from solution This topic has been investigated by Goddard and co-workers [16,17], mainly for Polyquaternium 10. Surface tension versus surfactant concentration measurements were obtained in the presence and in the absence of 0.1 % of the cationic Polyquaternium 10. This procedure was repeated for several surfactants. For some combinations of Polyquaternium 10 and surfactant there was a considerable lowering of the surface tension at the lower surfactant concentrations. For the rest there was no real change from the plot for the surfactant alone. Table 9.2 summarizes the results, which are illustrated in Fig. 9.2. It can be seen that a reduction in surface tension occurs only when an anionic surfactant is used in association with Polyquaternium 10. No change in surface tension is measured when an anionic detergent is tested with a nonionic, neutral polymer substituted for Polyquaternium 10. 'Change' infers a strong interaction between the anionic surfactant and the cationic polymer. Visual examination reveals a pattern of precipitation near the critical micelle concentration (the inflection point in curves shown in Fig. 9.2). It is reasonable to assume that the maximum precipitation occurs at ratios of polymer to surfactant at which the polymer charge is balanced by that of the surfactant, compliant with the expression: ( P S ^ + S-tPSi+l) 1 1 - 1 - 1 ?n+ l + nS -PS" where: n = positive charges S = surfactant P = polymer Finally, as the surfactant is increased the precipitate is redissolved. The technique is useful in screening additive-detergent systems for their propensity to deposit a complex which is potentially beneficial in a shampoo formulation. Having identified a case where a useful level of precipitation occurs, the next step is to determine how substantive (to hair) the precipitated material is. Goddard and Harris , using ESCA (electron spectroscopy for chemical analysis) determined the relative deposition of several cationic polymers. They also measured the substantivity of the deposits. It was established that certain cellulose-based cationics gave a high level of deposition but that it was fairly easily washed away by a dilute detergent solution. This would have the virtue for a product of avoiding the troublesome build-up of an active ingredient, i.e. one resisting removal by several shampooings. (b) Silicone additives The following are representative of silicone additives: dimethicone copolyols; block copolymers of dimethyl siloxane and ethylene oxide; and amodimethicones which contain an active amino group. Table 9.2 Effect of the ionicity of surfactant and polymer upon surface tension reduction Polymer Surfactant Polyquaternium 10 Sodium lauryl sulfate Sodium alkyl aryl sulfate Sodium laurate C14 betaine derivative Nonionic Cellosize Not Not Not Not X x x tested tested tested tested ^, Change; x , no change. surfactant surfactant + polymer No interaction Surface tension (dynes/cm) Interaction Detergent concentration (mol/l) 1Og scale c t p c Appearance Detergent concentration (mol/l) 10g scale Fig. 9.2 Surface tension versus concentration plots can reveal association between surfactant (detergent) and polymer. Appearance: c, clear; t, turbid; p, precipitates. Alexander  reports that silicone surfactants such as the dimethicone copolyols, when incorporated into shampoo formulations, greatly improve combing and antistatic properties at surprisingly low concentrations, 0.1-0.5%. Alexander also described another novel series of silicones, the amino-functional amodimethicones which, surprisingly, have good compatibility with anionic vehicles. Amodimethicones impart much the same benefits to hair as the dimethicone copolymers but have as an added feature a very good substantivity to its surface. This is not totally unexpected as the functional amino group is capable of forming an amine salt linkage with the free carboxyl groups of the hair surface; rather in the manner that the carboxyl groups of certain hairspray polymers are neutralized by treatment with amino alcohols. Starch  has described how the substantivity of the amodimethicones has been demonstrated using ESCA methods. (c) Proteins and amino acids In recent years the trend has been towards vegetable-derived materials such as those obtained from wheat, soya, maize or almond. All proteins are composed of amino acids, but the composition varies from protein to protein and this has a major bearing in performance on a substrate such as hair. It has been shown that protein derivatives can influence the mechanical properties of hair fibre, with beneficial effect. To do this there must be penetration into the cortex or some indirect effect on the cortex. The ability to do this will vary depending on size of molecule and charge. Gamez-Garcia  has reported on the use of hydrolysed wheat protein containing wheat oligosaccharides. Quaternization of the protein or amino acid reduces the ability to penetrate into the hair fibre, but increases the substantivity to the cuticle. (d) Ceramides Hussler et al.  have determined that the ceramide fractions present in a free form in human hair constitute about 0.01% of total hair weight. Their purpose is to bind the cuticle cells to the cortex and perform a 'barrier' function as a cell membrane complex in association with a proteinaceous matrix. The ceramide or lipid fraction is sensitive to chemical and physical attack such that extreme damage can lead to the cell membrane complex vanishing from the cuticle. Natural ceramides have a specific stereochemical configuration and show optical activity. This structure is essential for functionality. The common denominator for ceramides is that all contain a sphingoid base in amide linkage with nonhydroxy, alpha-hydroxy or omega-hydroxy acids. Synthetic ceramides have the ability to deposit on damaged hair locating in minute amounts in the cuticle layer. Increased protection against UV and visible radiation and limitation of the loss of water-soluble polypeptides are observable benefits. The phytosphingosine base linked with a nonhydroxy acid (ceramide 3) may have more benefit in restoring the hair to its natural balance than other classes of ceramides, which have restorative benefits on the skin. (e) Panthenol This is the provitamin of pantothenic acid or vitamin B5. Vitamin B5 is essential for normal hair growth and it has been found that use of panthenol in hair preparations can deliver vitamin B5 to the hair through its oxidation to the acid. Panthenol has also been shown to improve body and texture of hair together with a moisturizing capability. (f) Glutamic acid Glutamic acid derivatives are the subject of a Unilever Patent [231. Research has shown that these derivatives are a source of hair growth energy and that significant linear growth stimulation can be obtained. Penetration enhancers can potentiate the benefit by enhanced delivery to the area of hair follicle in closest proximity to the dermal papilla, where the energy demand is greatest. 9.5 ANTIDANDRUFF AGENTS Three agents associated with the treatment of scalp disorders have the following chemical structures. Zinc pyrithione (ZPT) was the first scientifically based organic therapeutic agent to offer alleviation of the scalp disorder known as dandruff. Dandruff manifests itself as the detachment of flakes of scalp skin. Almost contemporary with ZPT was another antidandruff agent, piroctone olamine (PO). Structurally it has little in common with ZPT except the presence of a pyridine ring. The relative and absolute effectiveness in shampoos of both piroctone olamine(PO) Triclosan Zinc pyrithione ZPT lrgasan DP300 Ciba Geigy Counter ion PO and ZPT was tested by Kligman et al. . Their work established that both were effective, but that PO was marginally and consistently superior. Futterer  has largely confirmed the earlier work. He has used both shampoos and cream rinses as vehicles for the antidandruff agents. From a manufacturer's point of view shampoos are the most acceptable vehicle for an antidandruff treatment. Futterer found that reductions in dandruff level of the order of 68% could be achieved for ZPT treatments but, under the same conditions, 82% when PO was the biologically active agent. The statistical significance of this difference in performance corresponds to p<0.05. He also experimented with different concentrations of the biologically active materials and found that 0.5% PO gave only a marginally different antidandruff performance to 0.75% ZPT. The lower concentration of PO needed for the desired result makes it preferable to the formulator. Bore and Goetz , like Breuer , are interested in the physical and chemical properties of sebum. They have compared the properties of healthy and seborrhoeic sebum and identified very large differences which are summarized in Table 9.3. The sebum samples were removed by a shampoo of the following constituents: % Sodium lauryl sulphate 4.30 Betaine derivative 2.00 Lactic acid 0.24 Water to 100.00 9.6 PREPARATION AND MANUFACTURE OF SHAMPOOS Relative to most other personal-care products the preparation of shampoos is uncomplicated and straightforward. Nevertheless, extreme care at the development stage of the formulation is necessary to ensure that the long-term stability, microbiological integrity and regulatory compliance concerning consumer safety and consumer acceptability have been addressed. Shampoo preparation does, however, have some specific problems. 9.6.1 Shampoo preparation Care must be exercised with regard to the solubility of various components. Stability tests can be made which will determine whether deactivation of functional additives through interaction between components is taking place. Table 9.3 Properties of healthy and sebborhoeic sebum Sebum Properties Quantity* % Squalene Iodine number Palmitic/oleic acids^ Viscosity proportional to Healthy Seborrhoeic Less 9% 80 1.0 1.5 Somewhat more 12% 100 0.7 0.7 *For the same extraction procedure. Ratio of saturated to unsaturated acids. f Example I A typically straightforward case where functional ingredients are inert towards the other components. 1. The main detergent, foam booster, the hair functional additive and water are mixed together with gentle stirring to minimize frothing. 2. Citric acid is added carefully to the above mixture to adjust the pH to within the limits 5.6-6.2. 3. A consistency adjuster, say Af-alkyl betaine, is added to the pH-adjusted blend with more vigorous stirring until the desired viscosity is attained. Example II Where some of the components are difficult to solubilize. 1. Dissolve the main detergent in the water. 2. Add the foam 'booster' to the above with stirring, and materials such as opacifiers and functional ingredients which present problems of dispersion. 3. Adjust the pH with citric acid to 5.6-6.2. 4. Adjust the viscosity with electrolyte additive (sodium chloride). Example III Where heat is needed to obtain solution. 1. Mix by propeller stirring the functional ingredient and the foam booster. 2. Using the same mixing regime add the main detergent to half the formulation water. 3. Add the mixture obtained in step (2) to that of step (1). 4. Separately use heat to disperse any difflcult-to-dissolve ingredient in the remainder of the water. 5. Add the product of step (4) to that of step (3). 6. Adjust the pH of the product to 5.6-6.2 by means of adding citric acid. Usually, with ingredients of the above solubility characteristics, no upwards adjustment of viscosity is needed. Note that Examples I and III represent clear shampoos and Example II is an opaque product. 9.7 REPRESENTATIVE SHAMPOO FORMULATIONS The major difference between the basic shampoo formulae is the level of surfactant used. 9.7.1 The Frequent Wash formula This is intended for daily use and has the lowest active concentration because the sebum level on the hair must be balanced. Too high an active concentration would remove the sebum in total with gross detrimental effect to the hair. The normal shampoo is designed for use every 3 or 4 days and has a correspondingly higher surfactant concentration. Frequent use % w/w Normal shampoo 7.70 2.00 0.10 q.s. q.s. q.s. to pH 6.0 q.s. to 100.00 13.50 2.00 0.10 q.s. q.s. q.s. to pH 6.0 q.s. to 100.00 Sodium Laureth Sulfate (70%A) Cocamidopropyl Betaine (30%A) Tetrasodium EDTA Preservative Perfume Colour Citric Acid Sodium Chloride Water (deionized); Aqua (INCI) 9.7.2 %w/w Conditioning shampoos These have grown considerably in importance in recent years. The newer formulations claim to wash and condition in one operation, leaving the hair easy to comb, lustrous and soft. Formulations of this type are complex, utilizing materials such as silicones and polyquaterniums. A great deal of care has to be taken to ensure that build-up on the hair is not excessive, and that silicone can be released on to the hair at the appropriate moment during rinsing. 2 in 1 Conditioning shampoo %w/w Sodium Laureth Sulfate (70%A) Cocamidopropyl Betaine (30%A) PEG 3 Distearate Polyquaternium 7 Dimethicone Copolyol Panthenol Tetrasodium EDTA Preservative Perfume Colour Citric Acid Sodium Chloride Water (deionized); Aqua (INCI) 9.7.3 11.50 5.00 2.00 0.25 3.00 0.30 0.10 q.s. q.s. q.s. to pH 6.0 q.s. to 100.00 Premium shampoos These claim to thicken, balance or add volume to the hair and have also appeared in recent years. They utilize somewhat higher surfactant levels and contain a variety of conditioning and moisturizing ingredients, e.g. modified silicones, wheat proteins, panthenol and natural extracts. Premium shampoo Sodium Laureth Sulfate (70%A) Cocamidopropyl Betaine (30%A) Sodium Lauryl Sulfate and Glycol Distearate and Cocamide MEA Guar Hydroxypropyltrimonium Chloride Panthenol Tetrasodium EDTA Preservative Perfume Citric acid Colour Water (deionized); Aqua (INCI) 9.7.4 % w/w 15.00 5.00 3.00 0.20 0.30 0.10 q.s. q.s. to pH 6.0 q.s. to 100.00 Antidandruff shampoos These are designed to alleviate dandruff, a scalp disorder which manifests itself as scaly flakes of scalp skin. There are various root causes for this complaint ranging from straightforward scalp irritations to eczema and seborrhoeic dermatitis. Zinc pyrithione was the first scientifically based organic therapeutic agent to offer alleviation of dandruff. Whilst being very effective in use, and substantive to hair and scalp, it is extremely irritant and has the disadvantage of being insoluble in water. More recently pyroctone olamine has been developed, a less irritant material which does have good aqueous solubility, thus enabling the development of clear antidandruff formulae. Clear antidandruff shampoo Sodium Laureth Sulfate (70%A) Cocamidopropyl Betaine (30%A) Piroctone Olamine Polyquaternium 7 Perfume Colour Citric Acid Sodium Chloride Water (deionized); Aqua (INCI) % w/w 11.50 5.00 0.70 0.30 q.s. q.s. to pH 6.0 q.s. to 100.00 Triclosan tends to be utilized in medicated shampoos where antimicrobial activity is desirable, but specific claims for dandruff alleviation are not made. 9.7.5 Baby shampoos These require extreme care in formulating where low irritancy is the major need. Use of a nonionic detergent such as polysorbate 20 can be recommended here. It does not contribute to the foaming capacity significantly but does reduce the irritancy potential of the selected anionic. The balance between polysorbate 20 and PEG 600 distearate also controls viscosity. Baby shampoo % w/w Magnesium Laureth Sulfate (27.5%A) Cocamidopropyl Betaine (30%A) Polysorbate 20 PEG 600 Distearate Preservative Perfume Citric Acid Colour Water (deionized); Aqua (INCI) 11.00 5.00 1.00 3.50 q.s. q.s. to pH 6.0 q.s. to 100.00 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. Lawrence, A.S.C. (1958) Disc. Faraday Soc, 25, 58. Lawrence, A.S.C. (1964) J. Phys. Chem., 64, 3470. Breuer, M.M. (1981) /. Soc. Cosmet. Chem., 32, 437-456. Gershbein, L.L. and Barburoa, K. (1984) Fette, Seifen, Anstrichmittel., 86, 121-128. Kligman, A.M. and Shelley, W.D. (1958) /. Invest. Dermatol., 30, 99. Curry, K.V. and Golding, S. (1971) J. Soc. Cosmet. Chem., 22, 691-699. Koch, J, Aitzetmiiller, G. et al (1982) /. Soc. Cosmet. Chem., 33, 317. Davies, J.T. and Rideal, N.K. (1963) Interfacial Phenomenon, p. 420. Academic Press, New York. Spangler, L. (1965) J. Am. Oil Chem. Soc, 42, 733-737. Chan, A.RC. Solubilisation Kinetic of Detergency. PhD thesis, Carnegie-Mellon University. (Statements in text connected with whole theme and conclusions.) Bore, P., Goetz, N. et al. (1980) Int. J. Cosmet. Sci., 2, 177. Ross, J. and Miles, D. (1941) Oil Soap, 18, 99. Hart, J.R. and Degeorge, M.T. (1980) J. Soc. Cosmet. Chem., 31, 223-236. Donaldson, B.R. and Messenger, E.T. (1979) Int. J. Cosmet. Sci., 1, 71-90. Kumanova, R. (1989) Manuf. Chem., Sept., 36-38. Goddard, E.D. et al. (1975) J. Soc. Cosmet. Chem., 26, 539-550. Faucher, J.A. and Goddard, E.D. (1976) J. Coll. Interface ScL, 55, 313-319. Goddard, E.D. and Harris, W.C. (1987) J. Soc. Cosmet. Chem., 38, 43-55. Alexander, R (1985) Manuf. Chem., Sept., 3 9 ^ 2 . Starch, M.S. (1984) Drug Cos. Ind., 38. Gamez-Garcia, M. (1993) / Soc. Cosmet. Chem., 44, 69-87. Hussler, G., Kaba, G., Francois, A.M. and Saint Leger, D. (1995) /. Soc. Cosmet. Chem., 17, 197-206. Unilever Patent (0572167 Al). Kligman, A.M., Marples, R.A. et al. (1974) /. Soc. Cosmet. Chem., 25, 73-81. Futterer, E. (1981) J. Soc. Cosmet. Chem., 32, 327-338. Bore, P. and Goetz, N. (1977) /. Soc. Cosmet. Chem., 28, 317-328.
© Copyright 2018