WO2013076061A2

WO2013076061A2 - Method for straightening hair

Info

Publication number: WO2013076061A2
Application number: PCT/EP2012/073068
Authority: WO
Inventors: Craig Jonathon FAIRGRIEVE; Ezat Khoshdel; Prem Kumar Cheyalazhagan Paul; Scott Robson
Original assignee: Unilever Plc; Unilever N.V.; Hindustan Unilever Limited; Conopco, Inc., D/B/A Unilever
Priority date: 2011-11-21
Filing date: 2012-11-20
Publication date: 2013-05-30
Also published as: WO2013076061A3

Abstract

A hair treatment composition comprising a hair straightening component, said component comprising the combination of chitosan and ascorbic acid. The invention also provides a method of straightening hair comprising the step of applying to the hair a hair treatment composition comprising the combination of chitosan and ascorbic acid and a method of making the hair treatment composition comprising the step of pre-mixing the chitosan and ascorbic acid in an aqueous process to provide an ionically complexed salt, followed by the step of adding the pre-mix to the hair treatment composition.

Description

METHOD FOR STRAIGHTENING HAIR

The invention relates to hair straightening compositions and also a method of straightening the hair.

Straight hair is seen by many consumers as desirable.

The objective of the invention is to provide an improved hair straightening composition.

In a first aspect the invention provides a hair treatment composition comprising comprising a hair straightening component, said component comprising the combination of chitosan and ascorbic acid. In a further aspect, the present invention provides a method of straightening hair comprising the step of applying to the hair a hair treatment composition according to the first aspect of the invention.

As used herein, the term "chitosan" includes chitosan and chitosan derivatives.

As used herein, all percentages are by weight.

The invention affords a straightening effect on hair without harsh chemicals or additional styling. However, this is not to say that further styling is outside the invention, as this may further enhance the effect. Ascorbic acid is unstable and easily reacts with the exterior environment such as air, oxygen, heat, and light. The oxidization reaction of the ascorbic acid produces the dihydroascorbate radical, the oxidization intermediate of the ascorbic acid due to the dissociation of the hydrogen ion. Only small amount of the ascorbic acid can normally be used as an active ingredient because of its unstable nature due to the fast oxidization. The invention allows the use of ascorbic acid as opposed to having to use its oxidation intermediates.

Preferably the chitosan and ascorbic acid combination comprises a chitosan - ascorbic acid complex, and preferably wherein the chitosan and ascorbic acid are present in the formulation as an ionically complexed salt. The chitosan and ascorbic acid are not covalently bonded. The invention excludes interpolymer complexes with chitosan eg. chitosan-polyacrylic acid. Preferably the ascorbic acid-chitosan ionic complex involves the amine groups of chitosan (as opposed to involving the hydroxyl groups).

Chitosan In the application of the hair care composition to the hair the problem of thin (low viscosity) liquid formulations arises. This is because it can be more difficult to apply without wastage as thinner liquid drips from the hair before it can take effect.

Accordingly chitosan is in the form of polyglucoseamine and not any of its associated oligomers eg. glucosamine which could impinge on viscosity levels.

Preferably the molecular weight of the chitosan is 5000 - 2,000,000 g/mol, and more preferably 10,000 - 1 ,000,000 g/mol and most preferably 50,000 - 500,000 g/mol.

This range is advantageous for assisting thickening without imposing problems of solubilising chitosan within the hair treatment composition.

Hair styling compositions in the form of creams or gels also typically contain a structurant or thickener, typically in an amount of from 0.01 % to 10% by weight of the total composition. The selection of the chitosan molecular weight means that thickener levels do not need increasing.

Preferably the hair treatment composition comprises a maximum of 10 wt% (of total composition) chitosan, preferably less than 3% and more preferably less than 2%. Most preferably the hair treatment composition comprises 1 %wt chitosan.

Preferably the chitosan comprises a linear polymer. Ascorbic Acid

Preferably the ascorbic acid is in the form of L-ascorbic acid. However racemic, and other stereo isomers may be used for example erythorbic acid.

The Chitosan -Ascorbic acid complex

Preferably the ratio of chitosan to ascorbic acid is less than 9: 1 on a %wt basis. Preferably the ratio of chitosan to ascorbic acid is less than 3: 1 and most preferably it is 1 : 1 . Preferably the level of the chitosan-ascorbic acid present in the composition is in the range is 0.1 -10 wt% or less and more preferably 0.01 - 3%

Preferably the chitosan-ascorbic acid mixture is incorporated into the hair treatment composition by means of an aqueous process.

The chitosan-acorbic acid complex may be wholly consisting of chitosan and ascorbic acid. However, the chitosan-acorbic acid complex may comprise other organic acids for example acetic acid, citric acid, maleic acid. The chitosan may be ionically complexed with said organic acids. Accordingly in a further aspect, the present invention provides method of making a hair treatment composition according to the invention comprising the step of pre- mixing the chitosan and ascorbic acid followed by combining the pre-mix with the hair care composition. Preferably the pre-mixing step is an aqueous process to provide an ionically complexed salt.

Preferably the hair treatment composition comprises greater than 14 % by weight water. It is advantageous if the composition further comprises an a -hydroxy acid acids and salts thereof, of particular interest are bis (a -hydroxy acids) and/or their salts, a -Hydroxy acids which are of most importance for use with the present invention are citric acid and tartaric acid and/or their salts. Compositions of the present invention are formulated into hair care compositions, especially products with hair straightening claims.

It is preferred if the products are left on hair after application and not immediately washed off (within 60 minutes of application). Such products are called "leave on" formulations.

Preferred product forms are leave on formulations such as gels, mousses, sprays, creams and aerosols. Creams and mousses are particularly preferred. It is preferable if the pH at 30°C of the composition is from 2.5 to 9, more preferably above 4, most preferably from 5 to 8.

Hair care compositions of the present invention can comprise a carrier, or a mixture of such carriers, which are suitable for application to the hair. The carriers are present at from about 0.5% to about 99.5%, preferably from about 5.0% to about 99.5%, more preferably from about 10.0% to about 98.0%, of the

composition. As used herein, the phrase "suitable for application to hair" means that the carrier does not damage or negatively affect the aesthetics of hair or cause irritation to the underlying skin.

Compositions according to the invention may comprise a buffer or pH adjuster. Preferred buffers or pH adjusters include weak acids and bases such

glycine/sodium hydroxide, citric acid, lactic acid, succinic acid, acetic salt and salts thereof. Frequently a mixture of buffering system is used such as sodium citrate and citric acid.

Carriers suitable for use with hair care compositions of the present invention include, for example, those used in the formulation of hair sprays, mousses, tonics, waters, creams gels, shampoos, conditioners, and rinses. The choice of appropriate carrier will depend on the particular product to be formulated. The carriers used herein can include a wide range of components conventionally used in hair care compositions. The carriers can contain a solvent to dissolve or disperse the styling compound being used, with water, the C1 -C6 alcohols, lower alkyl acetate and mixtures thereof being preferred. The carriers can also contain a wide variety of additional materials such as acetone, hydrocarbons (such as isobutane, hexane, decene), halogenated hydrocarbons (such as Freons) and volatile silicones such as cyclomethicone.

When the hair care composition is a hair spray, tonic, gel, or mousse the preferred solvents include water. Other solvents are possible e.g. ethanol, volatile silicone derivatives, and mixtures thereof. The solvents used in such mixtures may be miscible or immiscible with each other. Mousses and aerosol hair sprays can also utilise any of the conventional propellants to deliver the material as a foam (in the case of a mousse) or as a fine, uniform spray (in the case of an aerosol hair spray). Examples of suitable propellants include materials such as trichlorofluoromethane, dichlorodifluoromethane, difluoroethane, dimethylether, propane, n-butane or isobutane. A tonic or hair spray product having a low viscosity may also utilise an emulsifying agent. Examples of suitable emulsifying agents include nonionic, cationic, anionic surfactants, or mixtures thereof. If such an emulsifying agent is used, it is preferably present at a level of from about 0.01 % to about 7.5% by weight based on total weight of the composition. The level of propellant can be adjusted as desired but is generally from about 3% to about 30% by weight based on total weight for mousse compositions and from about 15% to about 50% by weight based on total weight for aerosol hair spray compositions.

Suitable spray containers are well known in the art and include conventional, non- aerosol pump sprays i.e., "atomisers", aerosol containers or cans having propellant, as described above, and also pump aerosol containers utilising compressed air as the propellant.

The formulation may include conditioning materials such as surfactants, cationic conditioners suitable for hair, quaternary silicone polymers, silicone based conditioners and their emulsions, and amino functional silicones and their emulsions.

Further general ingredients suitable for all product forms include, sun-screening agents, anti-dandruff actives, carboxylic acid polymer thickeners for hair shampoo and conditioner compositions and emulsifiers for emulsifying the various carrier components of the compositions of the invention.

The compositions of the present invention may also contain adjuncts suitable for hair care. Generally such ingredients are included individually at a level of up to 2, preferably up to 1 wt% of the total composition. Suitable hair care adjuncts, include amino acids, sugars and ceramides. The method of the invention may comprise the step of heating the hair following application. The hair may be heated to a temperature above 100°C, preferably above 150°C, more preferably above 180°C. The invention has the further advantage that successive applications of product according to the invention give enhanced straightening benefits. Preferably, the product of the invention is applied at least twice.

The following non-limiting examples further illustrate the preferred embodiments of the invention. All percentages referred to in the examples are by weight and refer to the total composition.

Examples Hair switches were treated with the following solutions:

1 - Water - no treatment as a control

2 - 0.1 ml Chitosan ascorbic acid complex

3 - 1 ml Chitosan ascorbic acid complex

Chitosan: CAS number 9012-76-4 purchased from Sigma Aldrich, product code 448869, Low Molecular Weight, 75-85% Deacetylated. Ascorbic acid: CAS number 50-81 -7 purchased from Sigma Aldrich, product code 255564 ACS Reagent >99%.

The chitosan ascorbic acid complex was prepared by adding chitosan to a solution of ascorbic acid, with an excess of ascorbic acid, the excess ascorbic acid was then removed by dialysis. Hair switches were treated with the following solutions:

1 - Water - no treatment as a control

2 - 0.1 ml Chitosan ascorbic acid complex

3 - 1 ml Chitosan ascorbic acid complex

The solutions were added to a wet hair switch (2g weight/10" long). The solution was applied by a syringe. Following application, each switch was rubbed manually between fingers for 30 seconds. Treated switches were then mounted to hang from a slotted bar and left to dry

The bar was then placed in front of a commercially available light box housed in a controlled humidity and temperature cabinet and equipped with a Zeiss AxioCam scientific digital camera.

The switches were captured in a single image and subsequently volume analysis was carried out by means of image processing software KS400 (Carl Zeiss Microscopy, LLC, United States. Each switch is detected and separated from neighbouring switches with a blue line, see Figure 1 . Two regions are identified by the software on each switch, the red 'core' and the green frizzy area. The volume of the switch is taken as the sum of both areas. The images are measured in mm² and compared against a calibration image.

Hair switches which had been treated with chitosan-ascorbic acid were found to display a lower volume and than those treated with water alone the volume of hair switches ater 45 minutes, this is shown in Table 1 . Table 2 shows that the chitosan-ascorbic acid solution remained clear after a week, while a solution of ascorbic acid becomes coloured indicating the formation of dehydroascorbic acid. Table 3 gives an example composition of a formulation containing the chitosan- ascorbic acid complex. Table 1

Table 2

The following is an example of a cream formulation for use with method of the invention.

Table 4

Example 3

Trade Name Supplier INCI Name

% as % as 100% Received

% %

Stearamidopropyl

Lexamine S-13 Innolex 0.50 0.50

Dimethylamine

Hydrenol

Cognis Cetearyl Alcohol 1.50 1.50 MY/Lanette S3

Nipagin M Clariant Methylparaben 0.20 0.20

White Mineral

Carnation Paraffinium Liquidium 1.00 1.00 Oil SU70

Wacker Belsil Dimethicone (and)

Wacker 1.00 1.7 HL999 Trideceth-5

Dimethylacryamide/

Ethyltrimonium Chloride

Methacrylate Copolymer

Ciba (Now part (and) Propylene Glycol

Tinovis CD 0.35 0.70 of BASF) Dicaprylate/Dicaprate

(and) PPG-1 Trideceth-6

(and) C10-C11

isoparaffin

Glycerine -G2289 or

Glycerin Sigma Aldrich 1.00 1.00

G7043

Vitamin C-

Ascorbic acid - chitosan As per example 3.0 chitosan

complex

water To 100

Claims

1 . A hair treatment composition comprising a hair straightening component , said component comprising the combination of chitosan and ascorbic acid.

2. A hair treatment composition according to claim 1 wherein the chitosan and ascorbic acid are present as an ionically complexed salt.

3. A hair treatment composition according to any preceding claim wherein the molecuar weight of the chitosan is 5,000- 2,000,000 g/mol, more preferably 10,000 -1 ,000,000 and more preferably 50,000 - 500,000 g/mol.

4. A hair treatment composition according to any preceding claim wherein the composition comprises less than 10 % by weight (of total composition) chitosan, preferably less than 3 % by weight and more preferably less than 2 % by weight.

5. A hair treatment composition according to any preceding claim wherein the level of the chitosan-ascorbic acid present in the composition is in the range 0.1 - 10% by weight.

6. A method of straightening hair comprising the step of applying to the hair a hair treatment composition of any of claims 1 -5.

7. A method of making a hair treatment composition according to any of claims 1 -6 comprising the step of pre-mixing the chitosan and ascorbic acid followed by combining the pre-mix with the hair care composition.

8. A method according to claim 7 wherein the the pre-mixing step is an

aqueous process to provide an ionically complexed salt.