WO2019076606A1

WO2019076606A1 - Method of strengthening hair

Info

Publication number: WO2019076606A1
Application number: PCT/EP2018/076337
Authority: WO
Inventors: Prem Kumar Cheyalazhagan Paul; Susan Pye
Original assignee: Unilever Plc; Unilever N.V.; Conopco, Inc., D/B/A Unilever
Priority date: 2017-10-20
Filing date: 2018-09-27
Publication date: 2019-04-25

Abstract

This invention relates to a method of strengthening the fibres of hair, in particular a method of strengthening oxidatively-treated hair, the method comprising the sequential steps of: (i) washing the hair; (ii) soaking the washed hair in an aqueous treatment composition, and (iii) drying the soaked hair; characterized in that the aqueous treatment composition comprises at least 0.5% by weight of N-formyl amino acid.

Description

METHOD OF STRENGTHENING HAIR

Field of the Invention This invention relates to a method of strengthening the fibres of hair, in particular oxidatively-treated hair.

Background of the Invention The purpose of bleaching is to eliminate or lighten the natural hair colour by the reaction of an oxidizing agent with the melanin pigment. Examples of oxidizing agents that can be used are hydrogen peroxide, potassium, sodium or ammonium salts of perborate, percarbonate, persulfate and percarbamide, and mixtures thereof.

Bleaches are also used during oxidative dyeing treatments. Oxidative (or "permanent") dye compositions comprise "precursor dyes" which are small molecules capable of diffusing into the hair. These molecules mainly belong to three classes of aromatic compounds: diamines, aminophenols and phenols. They are sufficiently small to diffuse in the hair shaft where, once activated by an oxidizing agent such as hydrogen peroxide, they further react with other precursors to form larger coloured complexes.

Oxidative treatments of hair are very popular with consumers since they provide good results which are relatively unaffected by light, shampooing and perspiration. However, the process is not without drawbacks. Repeated oxidative treatments over prolonged periods may damage or weaken hair, making it prone to breakage and reduced lustre.

Film-forming polymers are often used in treatments for damaged hair because they alter hair surface properties, imparting smoothing and gliding effects and shine, and have a significant impact on the macroscopic behavior of the hair array. However, film- forming polymers are by nature designed to provide hair fibres with a hydrophobic coating that may slow or prevent the penetration of actives. Therefore, such treatments may not provide intrinsic benefits to the fibre such as strengthening and repair. The polymers themselves may also deposit less effectively on damaged hair compared to virgin hair. The present invention addresses this problem. Summary of the Invention

Accordingly, in a first aspect, the present invention provides a method of strengthening the fibres of hair, the method comprising the sequential steps of washing the hair, soaking the washed hair in an aqueous treatment composition, and drying the soaked hair; characterized in that the aqueous treatment composition comprises at least 0.5% by weight of N-formyl amino acid.

In a second aspect, the invention provides use of an aqueous treatment composition comprising at least 0.5% by weight of N-formyl amino acid for the strengthening of hair fibres.

In the context of the present invention, the reference to "hair" typically means mammalian hair including scalp hair, facial hair and body hair, more preferably hair on the human head and scalp.

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. The word "comprising" is intended to mean "including" but not necessarily "consisting of" or "composed of." In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word "about".

Numerical ranges expressed in the format "from x to y" are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format "from x to y", it is understood that all ranges combining the different endpoints are also contemplated. Detailed Description of the Invention

The aqueous treatment composition for use in step (ii) of the method of the invention will typically comprise an aqueous continuous phase.

By "aqueous continuous phase" is meant a continuous phase which has water as its basis. Accordingly, the aqueous treatment composition will generally comprise at least 60%, preferably at least 65% and more preferably at least 70%, still more preferably at least 75%, even more preferably at least 80% or even at least 90% water by weight of the total composition. Preferably, the composition comprises no more than 99.5% and more preferably no more than 98% water by weight of the total composition. Other organic solvents may also be present, such as lower alkyl alcohols and polyhydric alcohols. Examples of lower alkyl alcohols include C1 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 aqueous treatment composition for use in step (ii) of the method of the invention comprises at least 0.5% N-formyl amino acid by weight of the total composition.

Suitable N-formyl amino acids include N-formyl standard amino acids and their derivatives. Typical examples are N-formyl alanine, N-formyl proline, N-formyl methionine, N-formyl valine, N-formyl leucine and N-formyl glycine. The most preferred N-formyl amino acid is N-formyl glycine.

The N-formyl amino acids may be used in the free acid form or in the form of salts such as the sodium, potassium, and ammonium salts, or the lower alkanolamine salts (such as mono-, di- and triethanolamine salts and mono-, di- and triisopropanolamine salts). Mixtures of any of the above-described forms may also be suitable.

Preferably the N-formyl amino acids is used in the free acid form, and at a level ranging from 0.5 to 6%, more preferably from 1 to 3% and most preferably from 1 .5 to 2.5% by weight of the total composition. An aqueous treatment composition for use in step (ii) of the method of the invention may suitably include a conditioning gel phase, which may be generally characterized as a gel (Ι_β) 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 (Ι_β) 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)-

1 2 4

in which R , R , R , and R 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.

1

In a preferred class of cationic surfactant of the above general formula, R is a C16 to

2 3 4

C22 saturated or unsaturated, preferably saturated, alkyl chain and R , R and R are each independently selected from CH3 and CH2CH20H, 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%, preferably from 0.2 to 5% and more preferably from 0.25 to 4% (by weight based on the total weight of the 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%, preferably from 0.1 to 8%, more preferably from 0.2 to 7% and most preferably from 0.3 to 6% (by weight based on the total weight of the 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.

An aqueous treatment composition for use in step (ii) of the method of the invention 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.

In step (i) of the method of the invention, the hair may be washed with water alone or with shampoo.

In step (ii) of the method of the invention, the washed hair is soaked in the aqueous treatment composition. Generally, any application amount of aqueous treatment composition that covers the hair to be treated suffices. Lesser amounts may be used, for example, if only a section of hair or just the hair tips are to be treated. The aqueous treatment composition is preferably uniformly delivered, for example by working it from the root end to the tip end of the hair. Preferably, the hair is soaked in the aqueous treatment composition at a temperature from 15 to 40°C, and more preferably at a temperature from 20 to 30°C.

Preferably, the hair is soaked in the aqueous treatment composition for a period ranging from 1 to 60 minutes, more preferably from 3 to 45 minutes.

At the end of the soaking period, it is preferred that the hair is dried or allowed to dry without rinsing the aqueous treatment composition from the hair. The soaked hair may be dried naturally 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.

The aqueous treatment composition may thus remain in contact with the hair after initial application for a period of at least 1 minute, and preferably up until the next wash, e.g. 24 to 72 hours after initial application.

The method of this invention is applied to oxidatively-treated hair.

As used herein, the term "oxidatively-treated hair" means hair which has been subjected to any treatment comprising at least one step of contacting the hair with at least one oxidizing composition. Examples of oxidative treatments for human hair are bleaching, dyeing or perming.

As used herein, the term "oxidizing composition" means a composition comprising at least one oxidizing agent suitable for use on hair, such as hydrogen peroxide, potassium, sodium or ammonium salts of perborate, percarbonate, persulfate and percarbamide, and mixtures thereof. Examples of such compositions are oxidative dye compositions and bleaching compositions.

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

Examples. Examples

Example 1 Twice-bleached dark brown European hair switches of length 25 cm and weight 2gms, were treated as follows:

Control: After initial washing, soaked for 30 minutes in water

Example 1 : After initial washing, soaked for 30 minutes in a 1 % aqueous solution of

N-formyl glycine

At the end of the soaking period the switches were left to dry and clippings from a few fibres were used to measure denaturation temperature Td using DSC. The results are shown in Table 1 .

Table 1

It can be seen from the results that treatment of bleached switches with N-formyl glycine according to the method of the invention (Example 1 ) provides a substantial and significant increase in Td of the treated fibres, when compared to control. This shows that the method of the invention has the potential to repair hair fibres which have been damaged by oxidative treatments such as bleaching.

The enhanced fibre strengthening provided by the method of the invention may also help to prevent or reduce further fibre damage in the future, whether caused by oxidative treatment or otherwise.

Example 2

The following formulation illustrates an aqueous treatment composition for use in the method of the invention. Ingredient % activity %w/w raw material

Behentrimonium chloride 70 1 .1429

Cetearyl alcohol 100 3.0

Perfume 100 0.60

Preservative 100 0.2

Dimethicone emulsion 70 1 .429

N-formyl glycine 100 1 .0

Water, minors 100 To 100%

Claims

A method of strengthening the fibres of hair, the method comprising the sequential steps of:

(i) washing the hair;

(ii) soaking the washed hair in an aqueous treatment composition, and

(iii) drying the soaked hair; characterized in that the aqueous treatment composition comprises at least 0.5% by weight of N-formyl amino acid.

A method according to claim 1 wherein the N-formyl amino acid is N-formyl glycine.

A method according to claim 1 or claim 2 wherein the composition comprises 0.5 to 6% by weight of N-formyl amino acid.

A method according to any one of the preceding claims wherein the hair is soaked in the aqueous treatment composition at a temperature from 15 to 40°C.

A method according to any one of the preceding claims, wherein the hair is soaked in the aqueous treatment composition for a period ranging from 3 to 45 minutes.

A method according to any one of the preceding claims, wherein at the end of the soaking period, the hair is dried or allowed to dry without rinsing the aqueous treatment composition from the hair.

A method according to any one of the preceding claims, wherein the hair is oxidatively-treated hair.

8 Use of an aqueous treatment composition comprising at least 0.5% by weight of N-formyl amino acid, for the strengthening of hair fibres.