WO2015074970A1

WO2015074970A1 - Method of shaping hair

Info

Publication number: WO2015074970A1
Application number: PCT/EP2014/074676
Authority: WO
Inventors: Andrew Malcolm Murray; Prem Kumar Cheyalazhagan Paul
Original assignee: Unilever Plc; Unilever N.V.; Conopco, Inc., D/B/A Unilever
Priority date: 2013-11-21
Filing date: 2014-11-14
Publication date: 2015-05-28

Abstract

The invention provides a method of shaping hair comprising the following sequential steps: (i) treating the hair by topical application of a hair treatment composition comprising from 2 to 25 wt% of an aliphatic polycarboxylic acid, (ii) mechanically shaping the treated hair, (iii) drying the shaped hair and (iv) mechanically re-shaping the dried hair; in which the aliphatic polycarboxylic acid has a pK_a (measured at 25°C in water) ranging from 2.5 to 4, and a dicarboxylic acid structure corresponding to the following general formula (I): HOOC-R-COOH (I) in which R¹ is a divalent, saturated or unsaturated, linear or branched hydrocarbyl radical having from 1 to 4 carbon atoms, and which may optionally be substituted with one or more hydroxyl groups; or a tricarboxylic acid structure corresponding to the following general formula (II): HOOC-CH₂-R-COOH (II)₂ in which R is a divalent, saturated or unsaturated, linear or branched hydrocarbyl radical having from 1 to 3 carbon atoms, which is substituted with one –COOH group and which may optionally be substituted with one or more hydroxyl groups.

Description

METHOD OF SHAPING HAIR

This invention relates to a method of shaping hair, and more particularly a method of shaping hair without breaking the hair disulfide bonds.

Many people with naturally kinky, curly, or even wavy hair often desire to straighten their hair. Permanent hair straightening compositions that are on the market are based on chemical treatment of the hair in a two-step process using reducing agents to break hair disulfide bonds, followed by a neutralisation or oxidation step to reestablish new disulfide bonds in the desired configuration. Such systems have various negatives associated with them; in that the process itself is difficult to conduct, in many instances this straightening process is undertaken by a qualified hairdresser in a professional salon. Furthermore the straightening process damages the hair, has an

unpleasant odour and can cause irritation to the scalp.

Surprisingly we have found that hair can be shaped without causing the chemical damage which is traditionally

associated with permanent hair straightening processes involving breakage of the hair disulfide bonds.

Advantageously the method of the invention does not

necessarily require the use of high temperature heated implements such as straightening irons and can be

accomplished by a consumer without intervention of a

professional hairdresser. Furthermore, hair shaped with the method of the invention remains shaped even after subsequent washing . The present invention provides a method of shaping hair comprising the following sequential steps:

(i) treating the hair by topical application of a hair treatment composition comprising from 2 to 25 wt% of an aliphatic polycarboxylic acid,

(ii) mechanically shaping the treated hair,

(iii) drying the shaped hair and

(iv) mechanically re-shaping the dried hair; in which the aliphatic polycarboxylic acid has a pK_a

(measured at 25°C in water) ranging from 2.5 to 4, and a dicarboxylic acid structure corresponding to the following general formula (I) :

HOOC-i^-COOH (I) in which R¹ is a divalent, saturated or unsaturated, linear or branched hydrocarbyl radical having from 1 to 4 carbon atoms, and which may optionally be substituted with one or more hydroxyl groups; or a tricarboxylic acid structure corresponding to the following general formula (II) :

HOOC-CH₂-R¹-COOH (II) in which R¹ is a divalent, saturated or unsaturated, linear or branched hydrocarbyl radical having from 1 to 3 carbon atoms, which is substituted with one -COOH group and which may optionally be substituted with one or more hydroxyl groups . Preferably R¹ in general formula (I) above is a divalent saturated linear alkyl radical of formula -[CH(X)]_n- in which n is an integer ranging from 1 to 3 and each X is

independently selected from -H and -OH.

Specific examples of such dicarboxylic acids include malonic acid and tartaric acid.

Preferably R¹ in general formula (II) above is a -C (H) (COOH) - CH₂- radical.

A specific examples of such a tricarboxylic acid is

tricarballylic acid. The aliphatic polycarboxylic acid as described above is formulated into a hair treatment composition for use in the method of the invention.

Preferably the level of the aliphatic polycarboxylic acid acid in such a formulated hair treatment composition ranges from 3 to 20 wt% and more preferably from 4 to 15 wt%, by weight based on the total weight of the hair treatment composition . Preferred hair treatment compositions for use in the

invention have a conditioning gel phase, which may be generally characterized as a gel (L ) surfactant mesophase consisting of surfactant bilayers. Such a conditioning gel phase may be formed from a cationic surfactant, a high melting point fatty compound and an aqueous carrier. Typically these components are heated to form a mixture, which is cooled under shear to room temperature. The mixture undergoes a number of phase transitions during cooling, normally resulting in a gel ( Lp ) surfactant mesophase consisting of surfactant bilayers.

Examples of suitable cationic surfactants which are useful for forming the conditioning gel phase include quaternary ammonium cationic surfactants corresponding to the following general formula:

[N (R¹ ) (R²) (R³) (R⁴) ]⁺ (X)- in which R¹, R², R³, and R⁴ are each independently selected from (a) an aliphatic group of from 1 to 22 carbon atoms, or (b) an aromatic, alkoxy, polyoxyalkylene, alkylamido, hydroxyalkyl , aryl or alkylaryl group having up to 22 carbon atoms; and X is a salt-forming anion such as those selected from halide, (e.g. chloride, bromide), acetate, citrate, lactate, glycolate, phosphate nitrate, sulphate, and

alkylsulphate radicals.

The aliphatic groups can contain, in addition to carbon and hydrogen atoms, ether linkages, and other groups such as amino groups. The longer chain aliphatic groups, e.g., those of about 12 carbons, or higher, can be saturated or unsaturated .

Specific examples of such quaternary ammonium cationic surfactants of the above general formula are

cetyltrimethylammonium chloride, behenyltrimethylammonium chloride (BTAC) , cetylpyridinium chloride,

tetramethylammonium chloride, tetraethylammonium chloride, octyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride,

octyldimethylbenzylammonium chloride,

decyldimethylbenzylammonium chloride,

stearyldimethylbenzylammonium chloride,

didodecyldimethylammonium chloride,

dioctadecyldimethy1ammonium chloride,

tallowtrimethylammonium chloride, cocotrimethylammonium chloride, dipalmitoylethyldimethylammonium chloride, PEG-2 oleylammonium chloride and salts of these, where the chloride is replaced by other halide (e.g., bromide), acetate, citrate, lactate, glycolate, phosphate nitrate, sulphate, or alkylsulphate .

In a preferred class of cationic surfactant of the above general formula, R¹ is a i to C₂₂ saturated or unsaturated, preferably saturated, alkyl chain and R², R³ and R⁴ are each independently selected from CH₃ and CH₂CH₂OH, preferably CH₃

Specific examples of such preferred quaternary ammonium cationic surfactants for use in forming the conditioning phase are cetyltrimethylammonium chloride (CTAC) ,

behenyltrimethylammonium chloride (BTAC) and mixtures thereof .

Mixtures of any of the above-described cationic surfactants may also be suitable. The level of cationic surfactant suitably ranges from 0.1 to 10 wt%, preferably from 0.2 to 5 wt% and more preferably from 0.25 to 4 wt% (by total weight of cationic surfactant based on the total weight of the hair treatment

composition) .

By "high melting point" in the context of this invention is generally meant a melting point of 25°C or higher. Generally the melting point ranges from 25°C up to 90°C, preferably from 40°C up to 70° C and more preferably from 50°C up to about 65°C.

The high melting point fatty compound can be used as a single compound or as a blend or mixture of at least two high melting point fatty compounds. When a blend or mixture of fatty compounds is used, the melting point means the melting point of the blend or mixture.

Suitable fatty compounds of this type have the general formula R-X, wherein R is an aliphatic carbon chain and X is a functional group (e.g. alcohol or carboxylic acid or a derivative thereof such as ester or amide) .

R is preferably a saturated aliphatic carbon chain

comprising from 8 to 30 carbon atoms, preferably from 14 to 30 carbon atoms, more preferably from 16 to 22 carbon atoms.

R can contain, in addition to carbon and hydrogen atoms, ether linkages, and other groups such as amino groups.

Preferably R is a linear alkyl chain comprising from 8 to 30 carbon atoms, preferably from 14 to 30 carbon atoms, more preferably from 16 to 22 carbon atoms.

X is preferably an -OH group.

Most preferably, the fatty compound is a fatty alcohol of general formula (¾((¾) _n OH, where n is an integer from 7 to 29, preferably from 15 to 21. Specific examples of suitable fatty alcohols are cetyl alcohol, stearyl alcohol, behenyl alcohol, and mixtures thereof. Cetyl alcohol, stearyl alcohol and mixtures thereof are particularly preferred. Mixtures of any of the above-described fatty compounds may also be suitable.

The level of fatty compound suitably ranges from 0.01 to 10 wt%, preferably from 0.1 to 8 wt%, more preferably from 0.2 to 7 wt% and most preferably from 0.3 to 6 wt% (by weight based on the total weight of the hair treatment

composition) .

The weight ratio of cationic surfactant to fatty compound is suitably from 1:1 to 1:10, preferably from 1:1.5 to 1:8, optimally from 1:2 to 1:5.

Advantageously, the method of the invention does not require the breakage of hair disulfide bonds, and hair treatment compositions for use in the invention do not require the incorporation of reducing agents. It is preferred that such materials, if included at all, are present in minor

quantities only.

The term "reducing agent" in the context of this invention means an agent which is effective to break hair disulfide bonds when applied to hair for a period ranging from about 3 to 15 minutes and at a temperature ranging from about 20 to 30 °C. Examples of such reducing agents are ammonium

thioglycolate (in a solution having a pH of between about 7 and 10.5), glyceryl monothioglycolate (employed at a pH of less than 7), thioglycolic acid, dithioglycolic acid, mercaptoethyl amine, mercaptopropionic acid, dithioglycolate and alkali metal or ammonium sulfites or bisulfites.

A hair treatment composition for use in the method of the invention will preferably include from 0 to 0.1 wt~6 , more preferably from 0 to 0.01 wt%, and most preferably from 0 to 0.001 wt% reducing agents as defined above (by weight based on the total weight of the hair treatment composition) .

Hair treatment compositions for use in the invention will generally comprise at least 60 wt%, preferably at least 70 wt% and more preferably at least 80 wt% water (by weight based on the total weight of the hair treatment

composition) . Preferably, the hair treatment composition comprises no more than 95 wt% and more preferably no more than 90 wt% water (by weight based on the total weight of the hair treatment composition) . Other organic solvents may also be present, such as lower alkyl alcohols and polyhydric alcohols. Examples of lower alkyl alcohols include Ci to C6 monohydric alcohols such as ethanol and isopropanol. Examples of polyhydric alcohols include propylene glycol, hexylene glycol, glycerin, and propanediol. Mixtures of any of the above described organic solvents may also be used.

The hair treatment composition may also incorporate other optional ingredients to enhance performance and/or consumer acceptability. Suitable optional ingredients include:

preservatives, colouring agents, chelating agents,

antioxidants, fragrances, antimicrobials, antidandruff agents, cationic conditioning polymers, styling ingredients, sunscreens, proteins and hydrolysed proteins. Preferably, the hair treatment composition is a single dose composition. The term "single dose" in the context of this invention means that the hair treatment composition is to be applied to the hair in one go. Preferably, the hair treatment composition is applied to the hair in the form of a 100 to 300 ml single dose, more preferably a 150 to 250 ml single dose.

Preferably, the hair treatment composition is applied to the hair at a temperature from 15 to 40°C, and more preferably at a temperature from 20 to 30°C.

Preferably, the hair treatment composition is applied to dry hair. The term "dry hair" in the context of this invention generally means hair from which free water (i.e. water disposed as a film or droplets on the cuticle surface) has been substantially removed. Hair may be dried by exposure to air, by use of a heated hair drying appliance, by rubbing with a water-absorbent article, or by a combination of any of these methods. Preferably, the dry hair will not have been washed or actively wetted, (such as by shampooing, conditioning, rinsing or otherwise treating with an aqueous composition) in the preceding 2 hours and more preferably in the preceding 3 hours prior to topical application of the hair treatment composition in accordance with step (i) of the method of the invention, and will have been permitted to acclimatise to atmospheric conditions. In such circumstances there is substantially no free water present which

interferes with the adsorption of the hair treatment

composition on application. A suitable indicator of dry hair in the context of this invention would be a hair fibre whose calculated water content does not exceed 25 wt% by weight based on the total weight of the hair fibre.

Preferably, the hair treatment composition is worked through the hair after topical application.

Preferably, the hair treatment composition is worked through the hair after application. Preferably, after working through the hair, the hair

treatment composition is then left to penetrate the hair for a period of at least 5 up to about 90 minutes, more

preferably for at least 15 up to about to 60 minutes and most preferably for at least 20 up to about 40 minutes. At the end of the treatment period, and before the

commencement of step (ii) of the method of the invention, the hair treatment is preferably rinsed from the hair (in a so-called "rinse-off" treatment method) .

Preferably the pH of the hair treatment composition ranges from 1 to 4, more preferably from 1.5 to 3.

In step (ii) of the method of the invention, the treated hair is mechanically shaped. Preferably, the hair is mechanically straightened. For example, the hair may be pulled, combed, smoothed, pressed or flattened into a straightened configuration. A hot tool, such as an electrically heated flat hair iron or hand-held hair dryer, may be used in the mechanical shaping step. Such tools apply high levels of heat directly to the hair. Most operate in the 45°C to 250°C range, and are usually employed at temperature settings ranging from 50 °C to about 220°C, depending on the particular tool.

However, the present inventors have surprisingly found that the use of hot tools is not essential in the method of the invention. This is especially advantageous for consumers who wish to reduce or avoid the exposure of their hair to high temperatures, for example if their hair is fragile or overprocessed from previous chemical treatments such as bleaching and perming. Accordingly the mechanical shaping of the hair in step (ii) of the method of the invention is preferably conducted at a temperature from 15 to 40°C, more preferably at a

temperature from 20 to 30°C.

Most preferably in step (ii) of the method of the invention the hair is mechanically straightened by combing it into a straightened configuration at a temperature from 20 to 30°C. Preferably in step (iii) of the method of the invention, the shaped hair is dried by exposure to air.

Preferably in step (iv) of the method of the invention, the dried hair is mechanically re-straightened by combing it into a straightened configuration at a temperature from 20 to 30°C.

The present inventors have surprisingly found that hair may be durably shaped by the method of the invention. The term "durably shaped" in the context of this invention means that the hair shape persists after washing. Preferably more than 50% of the hair shape persists after 3 washes.

The invention is further illustrated with reference to the following, non-limiting Examples. EXAMPLES

All ingredients are expressed by weight percent of the total formulation, and as level of active ingredient.

Rinse-Off Treatment

Dark brown European wavy#6 hair switches of length 25 cm and weight 2g, were dosed with 2ml each of 5% polycarboxylic acid solutions at pH 3 or below.

Once dosed the switches were combed straight and left to dry 20 minutes. They were subsequently rinsed for 30 seconds under the tap. They were further combed straight when wet and left to dry overnight. When dry, the switches were combed straight and images taken.

If the switches are visually straight then the volume of the switches shows the straightening benefit of the molecule. Volume refers to the projection of the switch image onto the screen and is given in mm².

Table 1 shows polycarboxylic acids which provide durable straightness benefits in a rinse-off treatment method with one treatment and subsequent rinse-off after at least 20 minutes . Table 1

Treatment Volume in mm %benefit over water

Water (control) 14278 0

5% tricarballylic acid at pH 2 11397 20.2

5% tricarballylic acid at pH 3 10343 27.6

5% tartaric acid at pH 2 11146 21.9

5% tartaric acid at pH 3 11859 16.9

5% malonic acid at pH 2 11220 21.4

5% malonic acid at pH 3 11950 16.3

Claims

1. A method of shaping hair comprising the following

sequential steps:

(ii) mechanically shaping the treated hair,

(iii) drying the shaped hair and

in which R¹ is a divalent, saturated or unsaturated, linear or branched hydrocarbyl radical having from 1 to 3 carbon atoms, which is substituted with one -COOH group and which may optionally be substituted with one or more hydroxyl groups .

2. A method according to claim 1, in which the aliphatic polycarboxylic acid is selected from malonic acid, tartaric acid and tricarballylic acid.

3. A method according to claim 1 or 2, in which the hair treatment composition includes from 0 to 0.001 wt% reducing agents (by weight based on the total weight of the hair treatment composition) .

4. A method according to any one of claims 1 to 3, in which the pH of the hair treatment composition ranges from 1.5 to 3.

5. A method according to any one of claims 1 to 4, in which the hair treatment composition is applied to the hair in the form of a 100 to 300 ml single dose, more preferably a 150 to 250 ml single dose.

6. A method according to any one of claims 1 to 5, in which the hair treatment composition is rinsed from the hair before the commencement of step (ii) .

7. A method according to any one of claims 1 to 6, in which the hair treatment composition is applied to dry hair.

8. A method according to any one of claims 1 to 7, in in step (ii) the hair is mechanically straightened by combing it into a straightened configuration at a temperature from 20 to 30°C.