EP0645998A4

EP0645998A4 - Microemulsified hair treatment products and methods of making same.

Info

Publication number: EP0645998A4
Application number: EP94914897A
Authority: EP
Inventors: Thomas W Clifton Iii; Peter H Cade
Original assignee: Croda Inc
Current assignee: Croda Inc
Priority date: 1993-04-23
Filing date: 1994-04-22
Publication date: 1996-10-16
Also published as: WO1994024987A1; BR9405210A; AU6712394A; EP0645998A1; JPH07508295A; CA2138049C; CA2138049A1

Abstract

The present invention relates to hair treatment formulations such as hair relaxers, permanent waving agents and depilatories. These formulations are produced utilizing a microemulsion. While it would be expected that such microemulsions would be more irritating than their macroemulsion counterparts, the opposite has been found to be true.

Description

MICROEMULSIFIED HAIR TREATMENT PRODUCTS AND METHODS OF MAKING SAME TECHNICAL FIELD

The present invention relates to the field of personal grooming products and methods of their production and, more particularly, to hair relaxers, permanent wave compositions and depilatories. BACKGROUND ART

Emulsions have been used for many years in personal grooming products and in particular hair products. Of these emulsions, macroemulsions are typically used in a variety of contexts including skin care, hair relaxers, and hair creams. Macroemulsions are particularly useful in that they are generally nonirritating to the skin. They are, however, generally opaque and have other properties which render them less desirable for certain cosmetic and grooming applications. Macroemulsions may also have poor shelf stability, particularly in the case of hair relaxers and related products.

In contrast, microemulsions are generally clear, have a glass-like resonance and have pleasant tactile qualities. Microemulsions have better shelf stability and produce products which are more appealing to the eye. Because the surfactant (amphiphilic surface active agents) content of microemulsions is relatively high, hair penetration is better. This makes microemulsions an attractive alternative as a cosmetic and grooming system. Unfortunately, the use of higher levels of amphiphilic surface active agents also has its disadvantages. As previously described, microemulsions are created by the use of relatively large concentrations of amphiphilic surface active agents, i.e. greater than about 10% by weight, as compared to macroemulsions, which rarely contain greater than about 5-7% by weight. These amphiphilic surface active agents are generally very irritating to the skin and eyes.

When one considers the composition of conventional styling products such as, hair relaxers, permanent waving agents and depilatories, it is not surprising that macroemulsions have been the emulsion system of choice. Formulations such as, for example, hair relaxers, often employ relatively strong caustic substances, such as various protein hydrolyzing agents, to break the disulfide bonds and peptide bonds which provide hair with its natural shape. These aggressive agents are extremely irritating to the skin and eyes. It is not surprising, therefore, that one would attempt to utilize an emulsion system in connection with these products which is as nonirritating as possible so as to minimize the overall irritation qualities of the resulting product. Certainly, the use of a macroemulsion system limits the degree of irritation to that caused by the hair relaxing caustic agent in the formulation. However, those qualities which have rendered macroemulsions less desirable in certain applications remain. For example, the resulting formulations are opaque and may have a cheesy appearance and/or may separate into phases. In attempting to appreciate the reasons for the resulting skin and eye irritation produced by caustic containing macroemulsions, applicants have studied the interrelationship between the various ingredients normally found in such caustic containing products. Based on that study, it was concluded that the size and uniformly of the particles of the internal phase (vesicles) contained within macroemulsions in some way correlated to the level of irritation. By reducing the size of the vesicle, i.e. forming a hair relaxer out of a microemulsion instead of a macroemulsion, it was therefore believed to be possible to reduce the level of skin irritation. This discovery, however, presented a dilemma. The solution to the irritation problems associated with caustic-containing macroemulsions seemed to require the use of an even more irritating microemulsion. One of ordinary skill in this art could certainly have predicted that the results of such a combination would be extremely negative. The problem of irritation should certainly be expected to be compounded.

However, applicants unexpectedly discovered that when a microemulsion including sufficient caustic to produce a hair relaxing formulation is produced, the caustic-containing microemulsion formulation is no more irritating to the skin than macroemulsion formulations also including the caustic. In fact, it has been found that the microemulsion formulations are often actually less irritating. This finding was totally unexpected.

Akhtar et al., U.S. Patent No. 5,068,101 relates to a hair relaxer cream. Akhtar et al . teaches the use of a highly alkaline, no-base hair relaxer cream composition which is phase-stable on ageing. The composition may be used directly as a no-base hair relaxer or as a no-lye cream. However, Akhtar et al . specifically teaches the formulation of an opaque relaxer cream using modified hectorite clay gellants, and emulsifying waxes in proportions and percentages which ensure the formation of a stable opaque emulsion cream. This is radically different from the present invention which seeks to produce clear hair treatment gels. The formulations taught by Akhtar et al . are not and cannot be microemulsions.

One object of the present invention is to provide a hair relaxing or other hair treating formulation with all the benefits of a microemulsion and with none of its detriments. It is also an object of the present invention to provide a microemulsified hair treatment product which is as or less irritating than a similarly composed macroemulsified hair treatment product.

It is another object of the present invention to provide a microemulsified hair treatment product capable of being a hair relaxer, permanent waving agent, or depilatory which is stable, clear, generally colorless, and generally less irritating when compared to similar macroemulsion formulations. DISCLOSURE OF INVENTION In accordance with these objects, and in one aspect of the present invention, there is provided a hair treatment product including: a microemulsion of water, at least one oil, at least one nonionic amphiphilic surface active agent capable of forming a microemulsion, the nonionic amphiphilic surface active agent being present in an amount which is sufficient to form a microemulsion, and a protein hydrolyzing or protein reducing agent present in an amount sufficient to relax hair. In a particularly preferred embodiment, the hair treatment product also includes at least one anionic amphiphilic surface active agent. The amounts of the amphiphilic surface active agents used are sufficient to form a microemulsion.

It is also an object of the present invention to provide a method of making a hair treatment formulation which contains caustic or a related compound and yet is a microemulsion.

In accordance with this object and in another aspect of the present invention, there is provided a method of producing a hair care product comprising the steps of forming a water phase including water; forming an oil phase including at least one nonionic amphiphilic surface active agent in an amount which is sufficient to form a microemulsion, and at least one oil, adding the water phase into the oil phase and adding a protein hydrolyzing or protein reducing agent thereto. Preferably, the method includes the steps of heating the separate phases and allowing the phases to cool after being mixed. In a more preferred embodiment, the oil phase also includes at least one anionic amphiphilic surface active agent. BEST MODE OF CARRYING OUT THE INVENTION

The hair treatment products of the present invention can be used as hair relaxers to straighten hair; permanent waving agents to break down hair's naturally occurring curl structure and replace it with a structure considered desirable by the wearer; or a depilatory for the complete removal of hair. Principally, but by no means exclusively, the functions of these products is dictated by the content of the protein hydrolyzing or protein reducing agent in the product and the length of time that these products are left in contact with the hair. Generally, products containing a relatively low content of protein hydrolyzing or protein reducing agent are classified as hair relaxing agents; formulations including an intermediate amount of protein hydrolyzing or protein reducing agents are considered permanent waving agents; and compositions including relatively high concentrations of protein hydrolyzing or protein reducing agents are considered depilatories. However, even the mildest formulation in accordance with the present invention can exhibit depilatory-like behavior if left in contact with hair for too great a period of time.

The hair treatment products of the present invention are all microemulsions. Therefore, the ingredients used in the various formulations and the amounts of their use must be consistent with the construction and maintenance of a microemulsion. The hair treatment products of the present invention generally include water, at least one oil, and at least one nonionic amphiphilic surface active agent, the combination of these amphiphilic surface active agents being capable of forming a microemulsion, and a protein hydrolyzing or protein reducing agent. In addition, the use of an anionic amphiphilic surface active agent is also contemplated. In fact, the inventors have found that by using a combination of both one or more nonionic and one or more anionic amphiphilic surface active agents, the amount of water and oil included in the microemulsion can be increased. Correspondingly, the relative amount of surface active agents can be reduced. This tends to result in even lower levels of irritation.

Water, in accordance with the present invention, can be conventional tap water, well water, bottled water, or the like. Preferably, however, deionized water is used. Water can constitute between about 5 and about 80 percent by weight of the entire composition, and, more preferably, between about 30 and about 70 percent by weight of the total formulation. This assumes a mixture of anionic and nonionic amphiphilic surface active agents. If only nonionic surface active agents are used, then water can constitute between about 10% and about 50% by weight of the total formulation. More preferably, water can be provided in an amount of between about 20% to about 40% by weight. Oil, in accordance with the present invention, is generally oleaginous, nonsoluble in water, low in viscosity, generally non-polar or low in polarity, able to produce a discrete phase when mixed with water, inert, unreactive, clear, and colorless. Oils, in accordance with the present invention, include propoxylated fatty alcohols, silicone oils, hexane, volatile (cyclic) silicone oils, vegetable oils, linear paraffinic oils, and, preferably, mineral oil. Light grade 70 SSU (Saybolt Seconds Universal) mineral oil was found to be particularly advantageous. However, any oil having an SSU of between about 30 to 350 should work well. Mixtures of two or more oils may also be desirable. If, as is preferred, a mixture of anionic and nonionic amphiphilic surface active agents are used, then oils in accordance with the present invention are preferably provided in an amount of between about 10% and about 50% by weight of the total composition. More preferably, about 10% to about 35% by weight of the formulation is oil. Even more preferably, about 10% to about 30% by weight of the formulation is oil. Where only nonionic amphiphilic surface active agents are used, the amount of oil useful ranges from between about 5% and about 30% by weight of the total composition. More preferably, the amount of oil ranging from between about 5% and about 20% is used.

By "'amphiphilic'-', it is understood that these compounds generally exhibit both hydrophillic and lipiphillic tendency. As an empirical observation, anionic amphiphilic surface active agents tend to be more hydrophillic in nature, and nonionic amphiphilic surface active agents tend to be more lipiphillic in nature. By "surface active", it is understood that these substances change the surface tension of water and act as bridges between oils and water. In so doing, surface active agents act as emulsifiers, solubilizers and as suspending agents. The total amount of amphiphilic surface active agents used in accordance with the present invention must be sufficient so as to form a stable, clear, generally colorless microemulsion of desirable tactile and visual qualities. The amount generally necessary to produce such a microemulsion ranges from between about 5 to about 50 percent by weight of the total composition, and more preferably, about 10 to about 45 percent. This is particularly true when using a mixture of nonionic and anionic amphiphilic surface active agents. The amount of total surface active agent useful when using nonionic amphiphilic surface active agents alone is usually higher, ranging from between about 10 and about 60 percent by weight. If less than 10 percent total amphiphilic surface active agent is provided, and, more particularly, if less than about 5 to 7 percent of such agents are provided, the resulting emulsion will be a macroemulsion. It is preferred in accordance with the present invention, however, that the total amount of amphiphilic surface active agent present be between about 15 and about 40 percent by weight.

As will be discussed again later, the amount of amphiphilic surface active agents used, particularly when used as part of an oil phase, generally ranges from between about 5% and about 30% by weight, i.e. about the same as the amount of oil used. If only nonionic amphiphilic surface active agents are used, then a higher amount thereof is required in the oil phase (i.e. greater than 1:1).

In some embodiments of the present invention, at least one nonionic amphiphilic surface active agent is used. The resulting microemulsions exhibit long-term stability, clarity and lower levels of irritation when compared to macroemulsions. In particularly preferred embodiments, however, a plurality of 2, 3 or more different nonionic amphiphilic surface active agents are used. This allows the formulation to tailor the microemulsion and formulate products with a variety of different qualities. Also, it is highly desirable to use a combination of both nonionic and anionic amphiphilic surface active agents to form the hair treatment microemulsions of the present invention. It is also highly desirable to use a plurality of both nonionic and anionic amphiphilic surface active agents in such hair treatment formulations. The use of both one or more anionic and one or more nonionic amphiphilic surface active agents provides the formulator with a great deal of flexibility.

As previously mentioned, anionic amphiphilic surface active agents tend to be more hydrophillic, and nonionic amphiphilic surface active agents tend to be more lipiphillic. In either event, by adjusting the ratio of the anionic amphiphilic surface active agents used and the nonionic amphiphilic surface active agent used, the overall properties of the microemulsion can be adjusted. Preferably, in accordance with the present invention, the ratio of anionic to nonionic amphiphilic surface active agents ranges from between about 1:1 to about 1:7, and more preferably, between about 1:1 to about 1:4. Most preferably, the ratio of anionic amphiphilic surface active agent to nonionic amphiphilic surface active agent is from between about 1:1 to about 1:2. A ratio of 1:1 is most desirable.

"Anionic amphiphilic surface active agents", in accordance with the present invention, are negative in overall charge, tend to form salts, and can interact favorably with the highly ionic protein hydrolyzing or protein reducing agents used. Anionic amphiphilic surface active agents may include amphoteric agents so long as they are in their basic form. Amphoteric agents may be either anionic or cationic, depending upon the pH. Such amphoteric agents may include proteins, amino acids, Zwitterions and the like.

Particularly preferred anionic amphiphilic surface active agents are phosphate esters of alkoxylated fatty alcohols and salts thereof. These may include compounds including mono and diphosphates which are ethoxylated or propoxylated. In addition, the fatty alcohols used in these compounds may be saturated, unsaturated, or polyunsaturated. Fatty alcohols are defined herein as being between about 10 and about 24 carbons in length. Fatty alcohols may be unsubstituted or substituted with, for example, hydroxide or halogen substituents. Most preferably, however, linear saturated and monounsaturated fatty alcohols of 12 to 22 carbons in length are used. Examples of suitable phosphate esters of alkoxylated fatty alcohols include oleth-3-phosphate (oleyl [ethoxy]-3-phosphate) (The "3" indicates 3 moles of ethoxy groups per mole of fatty alcohol or acid) , oleth-10-phosphate, laureth-3-phosphate, behenth-5- phosphate, erucith-3-phosphate, polypropylene glycol-10-cetyl ether phosphate, and a compound sold by Croda, Inc. under the trade name Crodafos SG, which is a cetyl phosphate ester of mixed propoxy and ethoxy ester compositions. Salts of these various anionic amphiphilic surface active agents may be used such as, for example, salts using amine salts such as DEA (diethanol amine) or LiOH, NaOH, KOH, NH₄OH, TEA, and the like.

Other forms of anionic amphiphilic surface active agents include, for example, phosphatidyl choline.

"Nonionic amphiphilic surface active agents" in accordance with the present invention have no overall charge or ionic character. Thus these compounds provide more balance between water and oil phases. Advantageously, these may include alkoxylated fatty alcohols such as ethoxylated fatty alcohols and mixtures of ethoxylated and propoxylated fatty alcohols. Other ethers of fatty alcohols are also contemplated. Fatty alcohols, as previously described, may be saturated, unsaturated or polyunsaturated and may include from between about 10 to about 24 carbons. More preferably, fatty alcohols used include between about 12 and about 22 carbons and are preferably either saturated or monounsaturated.

Another class of nonionic amphiphilic surface active agents useful in accordance with the present invention are alkoxylated sterols such as alkoxylated ethers of lanolin or phytosterols. Alkanolamides such as lauramide DEA may also be used.

Nonionic amphiphilic surface active agents in accordance with the present invention also include alkoxylated polyol esters such as ethoxylated sorbitan esters. Polyol fatty acid esters are also useful in accordance with the present invention such as sorbitan fatty acid esters. Fatty acids, like fatty alcohols previously described, may generally have between about 10 to about 24 carbons and may be saturated, unsaturated, or polyunsaturated. Preferably, however, they comprise between about 12 and about 22 carbons and are either saturated or monounsaturated. Alkoxylated fatty acids such as ethoxylated stearic acid may also be used.

Branched or normal low molecular weight polyols having seven or less carbons may also be advantageously used as nonionic amphiphilic surface active agents. These include, for example, propylene glycol, ethylene glycol, sorbitol, sucrose, 1,4 butanediol glycerine, and dipropylene glycol. In formulating the compositions of the present invention, the amphiphilic surface active agents used are combined in an oil phase with the oil previously described. However, certain amphiphilic surface active agents, such as, for example, nonionic branched or normal low molecular weight polyols of seven carbons or less are conveniently and readily soluble in water. Poly-polyols such as low molecular weight polyethylene glycol and polypropylene glycol may also be used. When such nonionic amphiphilic surface active agents are used, it is often advantageous to incorporate them in a water phase rather than in an oil phase. This is because of the ease of incorporating these compositions into the water phase and also because their incorporation therein tends to facilitate the later intermixing of an oil and a water phase to form a microemulsion. Up to about 15% by weight of these amphiphilic surface active agents may be present in the water phase.

It is also particularly desirable that the formulations of the present invention include upwards of three to five or more amphiphilic surface active agents. These include the use of a nonionic amphiphilic surface active agent such as a readily water soluble branched or normal low molecular weight polyol in the water phase as well as a mixture of two or more anionic amphiphilic surface active agents and two or more nonionic amphiphilic surface active agents in an oil phase. In some cases, it may also be desirable to add a sixth amphiphilic surface active agent such as an alkanol amide in the oil phase.

Particularly preferred formulations would include at least one and preferably two or more phosphate esters of alkoxylated fatty alcohols and salts thereof including a combination of generally lower molar ratio ethoxylate and a generally higher molar ratio ethoxylate. For example, a mixture of monounsaturated C18 phosphate ester having 3 moles of ethoxy substituent per mole of fatty alcohol and a monounsaturated C18 phosphate ester having up to 20 moles of ethoxy substituent per mole of fatty alcohol is desirable. These would be combined with at least one and preferably two or more alkoxylated fatty alcohols corresponding to the phosphate esters used. Of course, the degree of ethoxylation can vary widely. It is also most preferred to add a nonionic amphiphilic surface active agent which is water soluble.

Notwithstanding the multitude of different amphiphilic surface active agents used, the total content of amphiphilic surface active agents in the compositions of the present invention should be maintained at between about 10% and about 45% by weight. No more than about 10-15% by weight of the amphiphilic surface active agents should be disposed in a water phase with the balance being disposed in an oil phase. Finally, the compositions of the present invention include agents which are capable of cleaving the disulfide and peptide bonds that give hair its 1 0

normal shape. In general, these active species exist in one of two forms based upon the nature of their activity. One group of active ingredients acts by hydrolysis of the various peptide bonds in hair. These are referred to herein as protein hydrolyzing agents. Alternatively, various bonds in hair can be either generally or selectively reduced such as disulfide bonds. This also will result in the straightening, waving, or eventual destruction of hair. The agents which act by reduction are referred to herein as protein reducing agents.

Protein hydrolyzing agents are generally selected from the group consisting of alkaline earth metal hydroxides and alkali metal hydroxides or hydroxides of Group I and Group II metals. Also, such compounds as ammonium hydroxide, ethanolamine and other basic amines may be used. Particularly preferred hydrolyzing agents in accordance with the present invention consist of KOH, NaOH, and LiOH. Of course, mixtures are also possible. In fact, some compounds such as guanidine carbonate/calcium hydroxide and Ca(OH)₂ could also be used. However, there may be some sacrifice in terms of overall clarity.

In general, protein hydrolyzing agents can be used in an amount of between about 0.5% and about 18% by weight based on the total composition. Of course, the amount of such agents used in hair relaxers is generally considerably less than the amount used in depilatories. Generally, protein hydrolyzing agents are not used in permanent waving agents. More particularly, the amount of protein hydrolyzing agent used in hair relaxers is generally between about 1.0% and about 3% by weight while the amount of said compounds used in depilatories generally ranges from between about 6% to about 13% by weight of the total composition. Of course, more or less may be used as appropriate. Protein reducing agents in accordance with the present invention include metal or ammonium thioglycolates, metal or ammonium sulfites, metal or ammonium bisulfates, and cystine and its salts. The amounts of said protein reducing agents useful in accordance with the present invention range from between about 0.5 to about 15 percent by weight. The amounts of peptide reducing agents useful for hair relaxers is generally between about 0.5% and about 4% based on the total weight of the composition. Between about 2% and about 10% is used for permanent waving agents and between about 3% and about 15% by weight of the total composition is used for depilatories. Of course, mixtures of the various active agents may also be used. It is also possible to incorporate coupling agents into the compounds of the present invention. Coupling agents may assist in the formation and maintenance of the microemulsion as well as assisting the clarity and stability thereof. Coupling agents are generally selected from the group consisting of methanol, ethanol, isopropyl alcohol, and butanol. These coupling agents are generally added in an amount of up to about 10%. Coupling agents are advantageously added to the water phase prior to the formation of a microemulsion. When nonionic amphiphilic surface active agents such as the polyols previously described are used, it may not be necessary to include such coupling agents. Colors, perfumes and the like may also be incorporated into the microemulsions of the present invention as is conventional in the industry.

There are many methods for manufacturing the hair treatment products of the present invention. In one method, all of the ingredients are charged to a reactor and heated, with stirring, until a homogeneous mixture is achieved. Generally, the formulation is heated to between about 80-85°C and then cooled to about 35°C or less. During cooling, the microemulsion is established. If the hair treatment product is to be other than bulk packaged, it is preferred that the individual containers be filled prior to the complete establishment of the microemulsion. One preferred method in accordance with the present invention requires the separate and discrete formation of a water phase and an oil phase. In some cases, the water phase may be composed of just water. In other cases, the water phase may include water and a nonionic amphiphilic surface active agent such as the readily water soluble branched and normal low molecular weight polyol of seven carbons or less previously described and/or a coupling agent.

The oil phase includes at least one oil, preferably mineral oil, and at least one nonionic amphiphilic surface active agent. More preferably, an anionic amphiphilic surface active agent is also used. Even more preferably, a plurality of anionic and nonionic amphiphilic surface active agents are used. The water phase is then added to the oil phase, sometimes with mild heating (up to about 80-85°C) . Thereafter, the phases are agitated such that a microemulsion is formed upon cooling. The protein hydrolyzing or protein reducing agent used is next added to the microemulsion. If the microemulsion is disturbed, it may be possible to re-establish it by adding small amounts of either an anionic or a nonionic amphiphilic surface active agent such as, for example, an alkanolamide. The resulting microemulsions are clear, colorless or slightly yellow in color, pleasing to the eye and to the touch and remarkably less irritating than even macroemulsion based hair relaxers. Some are also glass-like in their resonance. To use hair relaxers in accordance with the present invention, the hair relaxing formulation is applied by hand to the hair of the subject so that it completely wets the hair of the user. The material is then combed through ensuring an even saturation of the product. The hair treatment formulation is left in contact with the hair for between about 15 and about 25 minutes. Hair should be taken to ensure that the material is not left on the hair longer than 25 minutes under normal circumstances. Then, the material is shampooed out using a neutralizing shampoo generally provided with hair relaxing kits. These shampoos conventionally include a pH indicator so that the user will know when the protein hydrolyzing and/or protein reducing agents used have been completely reacted or removed.

The foregoing will be better understood with reference to the following examples. These examples are for the purposes of illustration. They are not to be considered limiting as to the scope and nature of the present invention.

EXAMPLE 1 - USE OF NONIONIC AND ANIONIC AMPHIPHILIC

SURFACE ACTIVE AGENTS Twenty grams of Crodafos N3 Acid (oleth-3- phosphate where the "3" refers to use of 3 moles of ethoxy substituent per mole of fatty alcohol) manufactured by Croda Inc. , Edison, New Jersey; 15 grams of Crodafos N10 Acid also manufactured by Croda Inc. (oleth-10-phosphate where the "10" refers to use of 10 moles of ethoxy substituent per mole of fatty alcohol) ; 100 grams of Carnation mineral oil (light mineral oil U.S.P., viscosity 70 SSU), manufactured by Witco Chemical, Perth Amboy, New Jersey; 15 grams of Volpol 3, manufactured by Croda Inc. (oleth-3, fatty alcohol having 3 moles of ethoxy groups per mole of alcohol) ; and 15 grams of Volpol 10, manufactured by Croda Inc. (oleth-10, fatty alcohol having 10 moles of ethoxy groups per mole of alcohol) ; were charged to an 800 ml Pyrex beaker. This mixture constitutes the oil phase with the Crodafos N3 Acid and Crodafos N10 acid as the anionic amphiphilic surface active agents and the Volpol 3 and Volpol 10 as nonionic amphiphilic surface active agents. The mixture was heated to about 80°C on a hot plate with agitation provided by a propeller and a Cafra o mixer set at about 300 rpm.

While the oil phase is reaching temperature, a separate water phase was formulated in a second beaker. One-hundred ninety (190) grams of deionized water and 35 grams of propylene glycol were added to the second beaker. The propylene glycol is a nonionic amphiphilic surface active agent which is readily soluble in water. The water phase thus created was also heated and mixed as described for the oil phase. When both phases equilibrated at about 80°, the water phase was slowly added to the oil phase while heating and agitation of the oil phase continued. Shortly after all of the water phase had been added, the heat was removed from the first beaker.

In a third beaker, 60 grams of a 25 percent NaOH solution was prepared and the solution was added to the first beaker now containing the mixed oil and water phases. Mixing continued and the material was cooled such that a microemulsion formed. The microemulsion was clear with a very slight yellowish tint and fine, smooth texture. EXAMPLE 2 A formulation was prepared as described in

Example 1, including 244.5 grams of deionized water and 35 grams of glycerine in the water phase, 75 grams of Carnation mineral oil, 30 grams of oleth-3 and 17.5 grams of oleth-5 (an ethoxylated fatty alcohol with 5 moles of ethoxy groups per mole of fatty alcohol) in the oil phase and 30 grams of a 10 percent NaOH solution. After the oil and water phases were mixed and the NaOH added thereto, 35 grams of laura ide DEA (an anionic amphiphilic surface active agent) was added. The mixture was cooled and a slightly yellow microemulsion resulted having good clarity and texture. EXAMPLE 3

A hair treatment product was prepared as in Example 2, except that 15 grams of DEA oleth-3 phosphate, (Crodafos N3 Neutral sold by Croda Inc.) 20 grams of DEA oleth-10 phosphate (Crodafos N10 Neutral sold by Croda Inc.) (both anionic) and 20 grams of oleth-3 and 27.5 grams of oleth-5 (both nonionic) were used for the oil phase. The resulting microemulsion was of good clarity and texture, with a slight yellow tint. EXAMPLE 4

A microemulsion hair treatment product was formulated in accordance with Example 3, except that the water phase included 227.5 grams of deionized water and 35 grams of 1,4-butanediol as the water phase. In addition, 50 grams of lauramide DEA were used and added to the formulation after the sodium hydroxide was added to the mixed water and oil phases. The resulting microemulsion was of good texture and clarity. EXAMPLE 5 A hair treatment formulation as described in

Example 4 was prepared, except that 197.5 grams of deionized water and 35 grams of di-propylene glycol were used for the water phase and 60 grams of a 10 percent NaOH solution was used as the peptide hydrolyzing agent. The resulting microemulsion was of good texture and clarity. EXAMPLE 6

A hair treatment product was prepared in accordance with the procedures of Example 2, except 247.5 grams of deionized water and 35 grams of propylene glycol were used for the water phase. The oil phase included 75 grams of carnation mineral oil, 15 grams of oleth-3 phosphate, 20 grams of oleth-10 phosphate, 30 grams of oleth-3 and 15 grams of oleth-5. The peptide hydrolyzing agent consisted of 60 grams of a 10 percent NaOH solution. Fifty grams of lauramide DEA was added after the peptide hydrolyzing agent was added to the water and oil emulsion as described in Example 2. The resulting microemulsion was of good texture and clarity. EXAMPLE 7 A hair treatment product was formulated in accordance with the procedure described in Example 2, whereby the water phase included 212.5 grams of deionized water and 35 grams of dipropylene glycol and the oil phase included 75 grams of Carnation mineral oil, 20 grams of oleth-3 and 27.5 grams of oleth-5. Sixty grams of a 10 percent NaOH and 50 grams of lauramide DEA were also used. The resulting microemulsion was of good texture and clarity. EXAMPLE 8 A hair treatment formulation as described in

Example 2 was prepared, except that 245.5 grams of deionized water was used in the water phase. Seventeen (17) grams of DEA oleth-3 phosphate and 20 grams of DEA oleth-10 phosphate were used in the oil phase along with the oleth-3 and oleth-5. Additionally, 60 grams of 10 percent NaOH solution was utilized. The resulting microemulsion was of good texture and clarity. EXAMPLE 9

A hair treatment product was prepared in accordance with Example 5, except that the water phase included 197.5 grams of deionized water and the oil phase also included 12.5 grams of oleth-3 and 35 grams of oleth-5. The resulting microemulsion was of good texture and clarity. EXAMPLE 10

A hair treatment formulation was prepared in accordance with Example 2, wherein the water phase included 195 grams of deionized water, and 35 grams of glycerine and the oil phase included 100 grams of Carnation mineral oil, 15 grams of oleth-3, 25 grams of oleth-5, 15 grams of oleth-10 phosphate and 20 grams of oleth-3 phosphate. Sixty grams of 25 percent solution of NaOH was used as were 35 grams of lauramide DEA. The resulting microemulsion was of good texture and clarity.

EXAMPLE 11 - USE OF NONIONIC AMPHIPHILIC SURFACE ACTIVE AGENTS ALONE A hair treatment product was prepared in accordance with Example 1. The water phase included 165 grams of deionized water, 25 grams of propylene glycol and 35 grams of sorbitol. The oil phase included 25 grams of polypropylene glycol-15-stearyl ether, 30 grams of Carnation mineral oil, 30 grams of oleth-3 and 139 grams of ceteth-20, 20 mole ethoxylateed fatty alcohol After the water and oil phases were prepared and mixed, 50 grams of a 25 percent NaOH solution was added. After cooling, the material resulted in a microemulsion having a slightly yellowish tint with acceptable color and texture. EXAMPLE 12

The microemulsion based hair relaxer produced in accordance with Example 10 was topically applied to a number of subjects and the degree of irritation resulting was measured versus a macroemulsion without caustic and a macroemulsion based hair relaxer. Specifically, three adult subjects were exposed to topical applications of the microemulsion formed in accordance with Example 10, a control macroemulsion prepared by the inventors and a macroemulsion based hair relaxer sold under the trademark LUSTER'S S-CURL, manufactured by Luster Products, Inc. , Chicago, Illinois. Approximately two grams of each material were applied to separate one square inch portions of the underside of the forearm of each subject. The material was left in contact with the skin for approximately 15 minutes. After the end of that period, the subjects were questioned about irritation and/or burning sensations resulting from each test portion. The subjects were not told which test portion corresponded to which product. The material was then washed off of the forearm of each subject with soap and warm water and the exposed skin was then observed for redness and/or burning.

After 15 minutes, each of the three subjects was questioned about the degree of irritation and discomfort caused by each of the test patches. Each of the three subjects indicated that the control macroemulsion caused the least degree of irritation or discomfort. Each also characterized the microemulsion formation of the present invention as being more irritating than the control macroemulsion, but less irritating than the macroemulsion based hair relaxer. After the materials were washed off, the skin of each subject was observed. However, because the degree of contact was minimal (15 minutes) , no significant discoloration or burning was observed. EXAMPLE 13 - HAIR RELAXING EFFICIENCY

Hair relaxing efficiency is determined as a percent of relaxation. A single hair, usually hair from an Afro-American subject, is pressed between two microscope slides. A box is then drawn with a ruler and marker around the hair such that the box has the smallest possible perimeter while just barely containing the hair. The perimeter of the box is then determined. The hair is removed and is relaxed by the application of a hair relaxer under consideration. The process is then repeated. Relaxation efficiency is determined by dividing the determined perimeter of the box around the relaxed hair by the determined perimeter of the original hair with the result being multiplied by 100. Hair samples were tested in accordance with this procedure after being relaxed by use of the formulation of Example 10 and REALISTIC CONDITIONING CREAM RELAXER BRAND HAIR RELAXER BY REVLON. The Revlon product showed a percent relaxation of about 85%. The microemulsion product in accordance with Example 10 produced a 90% relaxation efficiency. EXAMPLE 14 - DAMAGE TESTING

Hair relaxing involves the breaking of various bonds within the hair. This also results in the damaging of the hair. Damage is measured by examining the amount of force required to elongate a hair by one percent both before and after it has been relaxed. The original hair is 100%. Damage is illustrated by a decrease in the derived percentage. The hair relaxer products described in Example 13 were utilized for this purpose. The Revlon product resulted in a 40% damage ratio while the microemulsion product in accordance with Example 10 illustrated damage, i.e. a reduction in the force necessary to elongate the fiber by one percent of 30%. Thus the hair treatment products in accordance with the present invention are not only equal to or better than other similar macroemulsion based products in terms of their performance, but they are also no more irritating than those macroemulsion based products. In fact, as testing has shown, these formulations are often superior in terms of a lower degree of irritation than their macroemulsion based counterparts.

The principles, preferred embodiments, and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular embodiments disclosed, since these are to be regarded illustrative rather than restrictive. Variations and changes may be made by others without departing from the spirit and scope of the invention. INDUSTRIAL APPLICABILITY

This application thus discloses a variety of microemulsions which are particularly useful as hair treatment products, and most particularly for hair relaxers to straighten hair, as permanent waving agents, or as a depilatory for the removal of hair. Furthermore, these products are far less irritating to the skin than what would have been expected.

Claims

1. A hair treatment product comprising a microemulsion of water and at least one oil characterized by at least one nonionic amphiphilic surface active agent capable of forming said microemulsion, said nonionic amphiphilic surface active agent being present in an amount which is sufficient to form said microemulsion, and a protein hydrolyzing or protein reducing agent. 2. The hair treatment product according to claim 1, characterized in that said protein hydrolyzing agent comprises a compound selected from the group consisting of alkaline earth metal hydroxides, alkali metal hydroxides, ammonium hydroxide ethanol amine, basic amines and mixtures thereof.

3. The hair treatment product according to claim 2, characterized in that said protein hydrolyzing agent comprises a compound selected from the group consisting of KOH, NaOH, LiOH, and mixtures thereof. 4. The hair treatment product according to claim 1, 2, or 3, characterized in that said protein hydrolyzing agent is present in an amount of between about 0.5 and about 18 percent by weight of the total composition. 5. The hair treatment product according to claim 4, characterized in that said protein hydrolyzing agent is present in an amount of between about 1.0 and about 3 percent by weight of the total composition.

6. The hair treatment product according to claim 4, characterized in that said protein hydrolyzing agent is present in an amount of between about 6 and about 13 percent by weight of the total composition.

7. The hair treatment product according to claim 1, characterized in that said protein reducing agent comprises a compound selected from the group consisting of a metal or ammonium thioglycolate, a metal or ammonium sulfite, metal or ammonium bisulfite and their salts, and mixtures thereof.

8. The hair treatment product according to claim 7, characterized in that said protein reducing agent is present in an amount of between about 0.5 and about 15.0 percent by weight of the total composition.

9. The hair treatment product according to claim 8, characterized in that said protein reducing agent is present in an amount of between about 0.5 and about 4.0 percent by weight of the total composition.

10. The hair treatment product according to claim 9, characterized in that said protein reducing agent is present in an amount of between about 2.0 and about 10.0 percent by weight of the total composition. 11. The hair treatment product according to claim 10, characterized in that said protein reducing agent is present in an amount of between about 3 and about 15.0 percent by weight of the total composition.

12. The hair treatment product according to claim 1, 2 or 3, characterized in that the total amount of said at least one nonionic amphiphilic surface active agent is between about 10 and about 60 percent by weight of the total composition.

13. The hair treatment product according to claim 1, 2 or 3, characterized in that said at least one nonionic amphiphilic surface active agent is selected from the group consisting of: ethoxylated fatty alcohols, mixtures of ethoxylated fatty alcohols and propoxylated fatty alcohols, alkanolamides, alkoxylated sterols, alkoxylated polyol esters, polyol fatty acid ester, and branched or normal low molecular weight polyols of seven carbons or less.

14. The hair treatment product according to claim 13, characterized in that said fatty alcohols and said polyol fatty acids include saturated, unsaturated, or polyunsaturated fatty alcohols or fatty acids of 10 to 24 carbons in length. 15. The hair treatment product according to claim 13, characterized in that said alkoxylated polyol esters are selected from the group consisting of sorbitan and sugar. 16. The hair treatment product according to claim 13, characterized in that said polyol fatty acid esters are selected from the group consisting of sorbitan fatty acid esters and sugar esters.

17. The hair treatment product according to claim 13, characterized in that said branched or normal low molecular weight polyols of seven carbons or less include one or more compounds selected from the group consisting of propylene glycol, ethylene glycol, glycerin, sorbitol, dipropylene glycol, and 1,4- butanediol.

18. The hair treatment product according to claim 1, further characterized by at least an anionic amphiphilic surface active agent.

19. The hair treatment product according to claim 18, characterized in that the total amount of said at least one anionic and said at least one nonionic amphiphilic surface active agent is between about 5 and about 50 percent by weight of the total composition.

20. The hair treatment product according to claim 18, characterized in that the total amount of said at least one anionic and said at least one nonionic amphiphilic surface active agent is between about 10 and about 45 percent by weight of the total composition.

21. The hair treatment product according to claim 17, characterized in that the ratio of said at least one anionic amphiphilic surface active agent and said at least one nonionic amphiphilic surface active agent is between about 1:1 to about 1:7.

22. The hair treatment product according to claim 17, characterized in that said at least one anionic amphiphilic surface active agent comprises a compound selected from the group consisting of phosphate esters of alkoxylated fatty alcohols and salts thereof, and amphoteric agents in their basic forms.

23. The hair treatment product according to claim 22, characterized in that said phosphate esters of alkoxylated fatty alcohols and salts thereof can be either mono or diphosphates, can be either ethoxylated or propoxylated and can include a saturated, unsaturated, or polyunsaturated fatty alcohol of between about 10 and about 24 carbons in length. 24. The hair treatment product according to claim 23, characterized in that said phosphate esters of alkoxylated fatty alcohols are selected from the group consisting of 01eth-3-phosphate and its salts, Oleth-5- phosphate and its salts, Oleth-10-phosphate and its salts, and polypropylene glycol-10-cetyl ether phosphate and its salts.

25. The hair treatment product according to claim 1 further characterized in that a coupling agent.

26. The hair treatment product according to claim 25, characterized in that said coupling agent is present in an amount of less than about 10 percent by weight of the total composition.

27. The hair treatment product according to claim 25 or 26, characterized in that said coupling agent is selected from the group consisting of methanol, ethanol, propanol and isopropyl alcohol, butanol.

28. The hair treatment product according to claim 1, 2 or 3, characterized in that said oil is provided in an amount of between about 5 and about 30 percent by weight of the total composition.

29. The hair treatment product according to claim 28, characterized in that said oil is provided in an amount of between about 5 and about 20 percent by weight of the total composition. 30. The hair treatment product according to claim 18, characterized in that said oil is provided in an amount of between about 10 and about 50 percent by weight of the total composition.

31. The hair treatment product according to claim 30, characterized in that said oil is provided in an amount of between about 10 and about 35 percent by weight of the total composition.

32. The hair treatment product according to claim 1, 2 or 3, characterized in that said oil is selected from the group consisting of mineral oil, propoxylated fatty alcohols, silicon oils, hexane, volatile cyclic silicone oils, vegetable oils, liver and paraffin oils.

33. The hair treatment product according to claim 1, 2 or 3, characterized in that said water is provided in an amount of between about 10 and about 50 percent by weight of the total composition.

34. The hair treatment product according to claim 33, characterized in that said water is provided in an amount of between about 20 and about 40 percent by weight of the total composition.

35. The hair treatment product according to claim 18, characterized in that said water is provided in an amount of between about 5 and about 80 percent by weight. 36. The hair treatment product according to claim 1, characterized in that said water is deionized water.

37. A hair treatment product comprising a microemulsion of water in an amount of between about 35% and about 70% by weight and at least one oil in an amount of between about 10% and about 30% by weight, characterized by at least one anionic and at least one nonionic amphiphilic surface active agent capable of forming said microemulsion, the total amount of said anionic and said nonionic amphiphilic surface active agents being present ranging between about 10% and about 45% by weight, said anionic and said nonionic amphiphilic surface active agent being present in a ratio of between about 1:1 and about 1:4; and a protein hydrolyzing or protein reducing agent present in an amount which is at least sufficient to relax hair. 38. The hair treatment product according to claim 37, characterized in that said at least one anionic and said at least one nonionic amphiphilic surface active agent includes a linear or branched low molecular weight polyol of seven carbons in length or less, a plurality of nonpolyol nonionic amphiphilic surface active agents and a plurality of anionic amphiphilic surface active agents.

39. The hair treatment product according to claim 38, characterized in that said plurality of anionic amphiphilic surface active agents comprises two or more phosphate esters of alkoxylated fatty alcohols and salts thereof.