WO2015155047A1

WO2015155047A1 - Method of shaping hair

Info

Publication number: WO2015155047A1
Application number: PCT/EP2015/056865
Authority: WO
Inventors: Nerea ORTUOSTE ELCORO; Prem Kumar Cheyalazhagan Paul
Original assignee: Unilever Plc; Unilever N.V.; Conopco, Inc., D/B/A Unilever
Priority date: 2014-04-10
Filing date: 2015-03-30
Publication date: 2015-10-15

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, the hair treatment composition comprising a solution or dispersion in which one or more N-acyl amino acid amides are dissolved or dispersed in an oily carrier, and (ii) mechanically shaping the treated hair. Advantageously the method of the invention does not require the use of reducing agents or high temperature straightening irons, and the hair remains shaped even after subsequent washing.

Description

METHOD OF SHAPING HAIR

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

Background and Prior Art

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 re-establish 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.

Summary of the Invention 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, the hair treatment composition comprising a solution or dispersion in which one or more N-acyl amino acid amides are dissolved or dispersed in an oily carrier, and (ii) mechanically shaping the treated hair.

Detailed Description and Preferred Embodiments

The hair treatment composition for use in the method of the invention comprises a solution or dispersion in which one or more N-acyl amino acid amides are dissolved or dispersed in an oily carrier.

Preferred N-acyl amino acid amides for use in the invention may be prepared from glutamic acid, lysine, glutamine, aspartic acid and mixtures thereof.

Particularly preferred are n-acyl glutamic acid amides corresponding to the following formula:

R²-NH-CO-(CH₂)₂-CH(NH-CO-R¹)-CO-NH-R² in which R¹ is an aliphatic hydrocarbon radical having from about 12 to about 22 carbon atoms, and R² is an aliphatic hydrocarbon radical having from about 4 to about 12 carbon atoms. Examples of these include n-lauroyl-L-glutamic acid dibutyl amide, n-stearoyl-L-glutamic acid diheptyl amide, and mixtures thereof.

Most preferred is n-lauroyl-L-glutamic acid dibutyl amide, also referred to as dibutyl lauroyl glutamide. This material is commercially available from Ajinomoto Co., Inc. under the trade name "GP-1 ". The total amount of N-acyl amino acid amide suitably ranges from 0.1 to 2%, preferably from 0.5 to 1 .5%, more preferably from 0.8 to 1 .2%, by weight based on the total weight of the solution or dispersion.

The term "oily carrier" in the context of this invention means any non-aqueous medium which is liquid at ambient temperature (25° C) and atmospheric pressure (760 mm Hg), and which is capable of dissolving or dispersing the N-acyl amino acid amide. Suitable oily carriers include ester oils, hydrocarbon oils, and silicone oils.

The term "ester oil" as used herein denotes an oil including at least one— C(0)OR group, where R is a hydrocarbyl group. The term "hydrocarbyl" as used herein denotes an aliphatic or alicyclic group consisting principally of atoms of carbon and hydrogen and optionally one or more functional groups chosen from hydroxyl, ester, ether and carboxyl. Aliphatic groups include, for example, alkyl groups, alkenyl groups or alkynyl groups and may be straight or branched chain.

Suitable ester oils for use in the invention include monoesters of formula R¹C(0)OR², in which R¹ is a C₂ to C₂4 monovalent hydrocarbyl group and R² is a C₆ to C₃o monovalent hydrocarbyl group. Specific examples of such materials include isopropyl myristate, isononanoic acid Cie-18 alkyl ester, 2-ethylhexyl palmitate, stearic acid 2-ethylhexyl ester, cetyl oleate, glycerol tricaprylate, coconut fatty alcohol caprate/caprylate, n-butyl stearate, oleyl erucate, isopropyl palmitate, oleyl oleate, hexyl laurate, myristyl myristate, cetearyl isononanoate and decyl oleate.

Suitable ester oils for use in the invention also include diesters of formula

R¹OC(0)R²C(0)OR³, in which R¹ and R³ are each independently selected from C₆ to Ci₃ monovalent hydrocarbyl groups and R² is a straight or branched chain C₂ to C₈ divalent saturated hydrocarbyl group. Specific examples of such materials include di-n-butyl adipate, di-(2-ethylhexyl) adipate, di-(2-ethylhexyl) succinate, di-isotridecyl acetate, ethylene glycol dioleate, ethylene glycol diisotridecanoate, propylene glycol di(2- ethylhexanoate), propylene glycol diisostearate, propylene glycol dipelargonate, butanediol diisostearate and neopentyl glycol dicaprylate.

Suitable ester oils for use in the invention also include polyol esters generated from the reaction of a polyol containing three or more hydroxyl groups in one molecule with one or more monobasic carboxylic acids. Polyols with three or more hydroxyl groups include C5 to C10 polyols (for example trimethylol propane, ditrimethylol propane, pentaerythritol, dipentaerythritol, and tripentaerythritol), monosaccharides (for example mannose, galactose, arabinose, xylose, ribose, apiose, rhamnose, psicose, fructose, sorbose, tagitose, ribulose, xylulose, and erythrulose) and sugar alcohols (for example sorbitol, mannitol and galactitol). Monobasic carboxylic acids include aliphatic carboxylic acids containing a linear or branched hydrocarbyl group which is preferably an alkyl chain or alkenyl chain, more preferably a C₆ to C22 alkyl chain or alkenyl chain (for example caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid, dimethyloctanoic acid, butylheptylnonanoic acid, hexenoic acid, octenoic acid, decenoic acid, dodecenoic acid, tetradecenoic acid, hexadecenoic acid, octadecenoic acid, eicosenoic acid, docosenoic acid, linoleic acid and linolenic acid). Specific examples of such materials include triesters of trimethylolpropane with C₆ to C10 monocarboxylic acids, such as capric acid, caprylic acid, pelargonic acid and mixtures thereof.

Preferred ester oils for use in the invention are isopropyl laurate, isopropyl myristate, isopropyl palmitate, ethylhexyl palmitate, neopentyl glycol diheptanoate, and

trimethylolpropane tricaprylate/tricaprate, and mixtures thereof.

The term "hydrocarbon oil" as used herein denotes an oil comprising principally atoms of carbon and hydrogen.

Hydrocarbon oils for use in the invention will generally have an average carbon chain length of about 20 carbon atoms or less, and include cyclic hydrocarbons, straight chain aliphatic hydrocarbons (saturated or unsaturated), branched chain aliphatic hydrocarbons (saturated or unsaturated) and mixtures thereof. Straight chain hydrocarbon oils will typically contain from about 6 to about 16 carbon atoms, preferably from about 8 up to about 14 carbon atoms. Branched chain hydrocarbon oils can and typically may contain higher numbers of carbon atoms, e.g. from about 6 up to about 20 carbon atoms, preferably from about 8 up to about 18 carbon atoms. A preferred hydrocarbon oil for use in the invention is light mineral oil. Mineral oils are clear oily liquids obtained from petroleum oil, from which waxes have been removed, and the more volatile fractions removed by distillation. The fraction distilling between 250°C to 300°C is termed mineral oil, and it consists of a mixture of saturated hydrocarbons, in which the number of carbon atoms per hydrocarbon molecule generally ranges from Ci o to C40. Mineral oil may be characterised in terms of its viscosity, where light mineral oil is relatively less viscous than heavy mineral oil. Typical viscosity values quoted for light mineral oil range from about 1 to about 30 mPa.s at 25°C. A commercially available example of a suitable light mineral oil for use in the invention is Sirius M40, with a carbon chain length C10 to C₂s, mainly C12 to C20, and a viscosity of about 4 mPa.s at 25°C.

Suitable silicone oils for use in the invention include linear or cyclic silicone oils having from 2 to 7 silicon atoms, these silicones being optionally substituted with alkyl or alkoxy groups of 1 to 10 carbon atoms. Specific silicone oils that may be used in the invention include octamethyltetrasiloxane, decamethylcyclopentasiloxane,

dodecamethylcyclohexasiloxane, heptamethyloctyltrisiloxane, hexamethyldisiloxane, decamethyltetrasiloxane, dodecamethylpentasiloxane, and mixtures thereof.

Mixtures of any of the above-described materials may also be suitable. Preferred oily carriers for use in the invention include isopropyl myristate,

trimethylolpropane tricaprylate/tricaprate, cyclomethicone and mixtures thereof, with trimethylolpropane tricaprylate/tricaprate being particularly preferred.

The total amount of oily carrier suitably ranges from 98 to 99.9%, preferably from 97.5 to 99.5%, more preferably from 98.8 to 99.2%, by weight based on the total weight of the solution or dispersion. Particularly preferred for use in the invention are solutions or dispersions of from 0.1 to 2% dibutyl lauroyl glutamide (by weight based on the total weight of the solution or dispersion) in from 98 to 99.99% (by weight based on the total weight of the solution or dispersion) of an oily carrier selected from isopropyl myristate, trimethylolpropane tricaprylate/tricaprate, cyclomethicone and mixtures thereof (most preferably

trimethylolpropane tricaprylate/tricaprate).

A solution or dispersion as described above and suitable for use in the invention will typically be a Newtonian liquid with a viscosity generally ranging from 0.5 to 100 mPa.s, more preferably from 1 to 40 mPa.s, at 25°C.

A solution or dispersion as described above and suitable for use in the invention will typically be prepared by admixture of the one or more N-acyl amino acid amides with the oily carrier. The admixture can be carried out at normal room temperatures (20 to 25°C) with no special processing steps such as heating or cooling required.

A fully formulated hair treatment composition for use in the invention may include further optional ingredients (in addition to the solution or dispersion as described above) to enhance performance and/or consumer acceptability.

For example, a hair treatment composition for use in the invention may include a conditioning gel phase, which may be generally characterized as a gel (Ι_· ) surfactant mesophase consisting of surfactant bilayers. Such a conditioning gel phase may be formed from a cationic surfactant, a high melting point fatty alcohol 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 (L) 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, hydroxyalkyi, 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, dioctadecyldimethylammonium 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 Ci₆ 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 gel 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 alcohol can be used as a single compound or as a blend or mixture of at least two high melting point fatty alcohols. When a blend or mixture of fatty alcohols is used, the melting point means the melting point of the blend or mixture. Suitable fatty alcohols of this type have the general formula R-OH, where R is an aliphatic carbon chain. Preferably R is a saturated aliphatic carbon chain comprising from 8 to 30 carbon atoms, more preferably from 14 to 30 carbon atoms and most 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.

Most preferably, the fatty alcohol has the general formula CH₃(CH₂)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 alcohols may also be suitable. The level of fatty alcohol 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 alcohol 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 30⁵C. 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%, 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.

Other optional ingredients which may be incorporated in a fully formulated hair treatment composition for use in the invention 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 40⁵C, and more preferably at a temperature from 20 to 30⁵C.

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, 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 10 up to about to 60 minutes and most preferably for at least 15 up to about 40 minutes.

The hair treated in accordance with step (i) of the method of the invention is preferably dried prior the commencement of step (ii). The 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 in step (ii) of the method of the invention, 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 45⁵C to 250⁵C range, and are usually employed at temperature settings ranging from 50°C to about 220°C, depending on the particular tool.

Particularly good results have been obtained when the hair is mechanically straightened in step (ii) of the method of the invention with a hot tool such as an electrically heated flat hair iron. In such a case, it is preferred that the operating temperature of the hot tool ranges from 50 to 200⁵C, more preferably from 100 to 150⁵C, and most preferably from 120 to 140⁵C.

Moreover, hair shaping benefits may also be observed without the use of hot tools such as those described above. This may be 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. For example, in step (ii) of the method of the invention the hair may instead be mechanically straightened by combing it into a straightened configuration at a temperature from 15 to 40⁵C, preferably at a temperature from 20 to 30⁵C.

Advantageously, the invention also provides a method for re-shaping hair in which hair which has been treated and shaped in accordance with steps (i) and (ii) as described above is rinsed, and mechanically re-shaped before and/or after drying.

Hair to be mechanically re-shaped as described above may be rinsed with water alone or with shampoo. Preferably in the mechanical reshaping step the hair is mechanically re- straightened by combing it into a straightened configuration at a temperature from 15 to 40⁵C, more preferably at a temperature from 20 to 30⁵C.

One or more (e.g. two or three) cycles of rinsing, mechanical re-shaping and drying as described above may be carried out.

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.

Examples 1 to 4

Dark brown European wavy#6 switches of length -25 cm and weight 2g were dosed with 0.5g of the following test formulations respectively:

Example 1 : 1 % solution/dispersion of GP-1 (dibutyl lauroyl glutamide, ex Ajinomoto

Co., Inc.) in IPM(isopropyl myristate)

Example 2: 1 % solution/dispersion of GP-1 in a 67:33 ratio mixture of IPM and Dow

Corning® DC245 Fluid(decamethylcyclopentasilioxane) Example 3: 1 % solution/dispersion of GP-1 in PureSyn®

3E20 (trimethylolpropanetricaprylate/tricaprate, ex Exxon Mobil Chemical Company)

Example 4: 1 % solution/dispersion of GP-1 in Sirius® M40 (light mineral oil)

Example A: neat IPM

Example B: neat 67:33 ratio mixture of IPM and Dow Corning® DC245 Fluid Example C: neat PureSyn® 3E20 Example D: neat Sirius® M40

Examples 1 to 4 represent formulations in accordance with the invention. Examples A to D represent control formulations.

The switches were left to dry at room temperature for at least 1 hour. When dry the switches were straightened 7 times with low heat irons (set at 130 °C).

The switches were rinsed once for 30 seconds under tap water.

Once the switches were dried, they were washed once with anionic surfactant solution (14wt% aqueous solution of sodium lauryl ether sulphate; 0.2g applied per switch). The washing included gentle massaging (root to tip downward motion only) for 30 seconds and rinsing for another 30 seconds.

The switches were left to dry overnight at room temperature.

Pictures were taken of the switches treated with Examples 1 to 4 and A to D respectively.

The switches were washed a second and a third time and pictures were taken after drying overnight after each wash.

The results are shown in Table 1 below. The volume of a switch is a measure of the straightness of the treated switches. (Here volume refers to the projection of the switch image on to the screen and is given in mm²).

Table 1

EXAMPLE volume (in mm²) % benefit (over control) after 1 after after after 1 after after wash 2 wash 3 wash wash 2 wash 3 wash

1 3847 8599 13227 69,3 38.9 -4.0

A 12532 14077 12716

2 5651 1 1019 1 1860 53,7 13,2 "18.8

B 12218 12695 9984

3 181 1 2558 8643 84.3 79.9 27.9

C 1 1572 12748 1 1992

4 4055 7087 1 1281 66.0 43,3 3,3

D 1 1923 12505 1 1668 It can be seen from the results that the formulations of Examples 1 to 4 respectively give excellent straightness durability benefits up to 2 washes compared to the formulations of Examples A to D respectively. Moreover the formulation of Example 3 gives a substantial benefit even after the 3^rd wash.

Claims

1 . A method of shaping hair comprising the following sequential steps: (i) treating the hair by topical application of a hair treatment composition, the hair treatment composition comprising a solution or dispersion in which one or more N-acyl amino acid amides are dissolved or dispersed in an oily carrier, and

(ii) mechanically shaping the treated hair.

2. A method according to claim 1 , in which the one or more n-acyl amino acid amides are selected from n-acyl glutamic acid amides corresponding to the following formula:

R²-NH-CO-(CH₂)₂-CH(NH-CO-R¹)-CO-NH-R² in which R¹ is an aliphatic hydrocarbon radical having from 12 to 22 carbon atoms, and R² is an aliphatic hydrocarbon radical having from 4 to 12 carbon atoms.

3. A method according to claim 2, in which the n-acyl glutamic acid amide is n- lauroyl-L-glutamic acid dibutyl amide.

4. A method according to any one of claims 1 to 3, in which the oily carrier is selected from isopropyl myristate, trimethylolpropane tricaprylate/tricaprate,

cyclomethicone and mixtures thereof.

5. A method according to claim 4, in which the oily carrier is trimethylolpropane tricaprylate/tricaprate.

6. A method according to any one of claims 1 to 5, in which the solution or dispersion has a viscosity ranging from 1 to 40 mPa.s, at 25°C.

7. A method according to any one of claims 1 to 6, in which the hair is mechanically straightened in step (ii) with a hot tool with an operating temperature ranging from 100 to 150⁵C.

8. A method according to any one of claims 1 to 6, in which the hair is mechanically straightened in step (ii) by combing it into a straightened configuration at a temperature from 20 to 30^gC.

9. A method according to any one of claims 1 to 8, comprising the further steps of rinsing and mechanically re-shaping the hair before and/or after drying the hair.