WO2014102324A1

WO2014102324A1 - Dyeing method employing a dye and a chaotropic salt

Info

Publication number: WO2014102324A1
Application number: PCT/EP2013/078051
Authority: WO
Inventors: Boris Lalleman; Claude Dubief
Original assignee: L'oreal
Priority date: 2012-12-27
Filing date: 2013-12-27
Publication date: 2014-07-03
Also published as: FR3000388B1; FR3000388A1

Abstract

The invention relates to a method for dyeing keratin fibres, employing : - one or more chaotropic salts, - one or more dyes, in a single composition or two different compositions, the chaotropic salt or salts being present in an amount of from 50% to 90% by weight o f the composition or compositions comprising it or them.

Description

Dyeing method employing a dye and a chaotropic salt

The present invention relates to a method for dyeing keratin fibres, more particularly human keratin fibres such as the hair, employing at least one chaotropic salt and at least one dye in a single composition or two different compositions .

The field o f the dyeing o f human keratin fibres, such as the hair, encompasses oxidation dyeing or permanent dyeing. More particularly, this dyeing method uses one or more oxidation dye precursors and usually one or more oxidation bases optionally combined with one or more couplers .

In general, oxidation bases are chosen from ortho- or para- phenylenediamines, ortho- or para-aminopheno ls and heterocyclic compounds . These oxidation bases are colourless or weakly coloured compounds which, in combination with oxidizing products, provide access to coloured species by a method of oxidative condensation.

The shades obtained with these oxidation bases are often varied by combining them with one or more couplers, these couplers being chosen especially from aromatic meta-diamines, meta- aminopheno ls, meta-dipheno ls and certain heterocyclic compounds, such as indo le compounds.

The variety o f the mo lecules employed as oxidation bases and as couplers allows a rich palette of co lours to be obtained.

This type of oxidation dyeing can be used to obtain permanent dyeings, but gives rise to degradation o f the keratin fibres through the use o f chemical oxidizing agents such as hydrogen peroxide.

Direct dyeing or semi-permanent dyeing is also known. The method conventionally used in direct dyeing invo lves applying direct dyes to the keratin fibres, said dyes being co loured and co louring mo lecules having an affinity for the fibres, leaving them on to allow the mo lecules to penetrate to the inside of the fibre by diffusion, and then rinsing them o ff. The direct dyes generally employed are chosen from direct nitrobenzene, anthraquinone, nitropyridine, azo, xanthene, acridine, azine or triarylmethane dyes, and natural dyes.

These dyes may be nonionic, anionic, cationic or amphoteric.

The compositions comprising one or more direct dyes are applied to the keratin fibres for a time required for the desired co loration to be obtained, and then rinsed off. The resulting co lorations are generally chromatic co lorations which are nevertheless temporary or semi-permanent, since the nature of the interactions binding the direct dyes to the keratin fibre, and their desorption from the surface and/or the core of the fibre are responsible for their low co louring power and their poor resistance to washing or to perspiration.

There is therefore still a need for dyeing hair in a satisfactory manner, using products which can be natural in origin, without employing a chemical oxidizing agent, and for enhancing the co loration in terms of development of the co lour, more powerful and more resistant dyeings, especially resistant to shampoos, while respecting the nature of the hair.

The applicant has discovered that, surprisingly, a method for dyeing keratin fibres that employs a particular amount of at least one chaotropic salt and at least one dye, in a single composition or two different compositions, allows the aforementioned problems to be reso lved and the aforementioned needs to be met.

The invention accordingly provides a method for dyeing keratin fibres, more particularly human keratin fibres, such as the hair, employing one or more chaotropic salts and one or more dyes, in a single composition or two different compositions, the chaotropic salt or salts representing 50% to 90% by weight relative of the composition or compositions comprising it or them.

This method enables in particular the acquisition of improved development of the co lour, more powerful dyeing of hair, and a dyeing which is more resistant to shampoos . The chaotropic salt may be applied at the same time as the dye or dyes, before and/or after the dyeing step, or before and/or after the dyeing step and at the same time as the dye or dyes, but is preferably fo llowed by a rinsing step . The chaotropic salt is more particularly applied before the dyeing step . A rinsing step may be provided after the application o f the chaotropic salt and/or after the dyeing step .

The invention accordingly also provides a preferred method for dyeing keratin fibres, more particularly human keratin fibres such as the hair, which comprises :

- the application o f a first composition comprising one or more chaotropic salts in an amount of from 50 % to 90 % by weight relative to the total weight of the first composition,

- rinsing or wringing, preferably wringing,

- the application o f a second composition comprising one or more dyes, and

- optionally a final rinsing.

Lastly, the invention also relates to a device implementing the compositions of the method of the invention.

Other subj ects, characteristics, aspects and advantages of the invention will become even more clearly apparent on reading the description and examples that fo llow.

In the text below, unless indicated otherwise, the end points o f a range of values are included in that range, particularly in expressions "of between ... " and "of from ... to ... ".

Furthermore, the expression "at least one" when used in the present description, is equivalent to the expression "one or more" .

According to the invention, the method for dyeing keratin fibres employs one or more chaotropic salts and one or more dyes, in a single composition or two different compositions, the chaotropic salt or salts being present in an amount of from 50% to 90% by weight relative to the total weight of the composition or compositions comprising it or them.

A "chaotropic agent" is a mo lecule which modifies the spatial (three-dimensional) structure in bio logical macromo lecules, such as proteins, DNA or RNA, and denatures said structure reversibly [see, for example, Eur. J. Biochem . 40_., 63 1 -636 ( 1973); J. Biol. Chem. , 248 , 8429-8433 ( 1 973); Br. J. Pharmacol. , 109, 779-787 ( 1993); and Protein Science, 5 , 2020-2028 ( 1996)] .

A chaotropic agent or agents are known by the skilled person to interfere with the low-energy, i. e. non-covalent, intramo lecular interactions, such as ionic bonds, hydrogen bonds, bonds invo lving Van der Waals forces, including Keesom, Debye and London forces, and hydrophobic interactions o f π stacking type, (71- or 71- 71-) or between long hydrophobic hydrocarbon chains comprising preferably more than 8 carbon atoms. The chaotropic agent or agents of the invention are one or more chaotropic salts .

The chaotropic salt(s) used in the method of the invention is (are) chosen from guanidine salts, aminoguanidine, salts o f alkali metals, alkaline earth metal salts and mixtures thereo f.

Chaotropic salts include, in particular, guanidine salts o f organic or inorganic acids, such as guanidine hydrochloride, guanidine thiocyanate, guanidine carbonate and guanidine phosphate; aminoguanidine salts such as aminoguanidine hydrochloride and aminoguanidine bicarbonate; salts of alkali metals such as lithium, such as lithium halides and more particularly lithium bromide; alkaline earth metal salts such as magnesium salts, such as magnesium halides; and mixtures thereof.

Chaotropic salts include more particularly the guanidine salts of organic or inorganic acids, such as guanidinium halides, guanidinium thiocyanates, guanidinium carbonates; lithium salts such as lithium halides and preferably lithium bromide; and mixtures thereo f.

Particularly preferred chaotropic salts are guanidine salts, more particularly guanidine salts with a mineral acid, such as guanidine hydrochloride; alkali metal halides, more particularly lithium halides such as lithium bromide; and mixtures thereo f. The amount of chaotropic salt or salts is from 50% to 90% by weight, preferably from 50%> to 80%> by weight, relative to the total weight of the composition or compositions comprising it or them.

According to the invention, the method also employs one or more dyes .

The dye or dyes is or are chosen from oxidation dyes, synthetic direct dyes, natural dyes, and mixtures thereof, and more particularly from synthetic direct dyes, natural dyes and mixtures thereof.

The oxidation dyes are generally chosen from oxidation bases optionally combined with one or more couplers .

As examples, the oxidation bases are chosen from para- phenylene diamines, bisphenylalkylenediamines, para-aminophenols, ortho-aminopheno ls, heterocyclic bases and addition salts thereof.

Examples among the para-phenylenediamines include para- phenylenediamine, para-tolylenediamine, 2-chloro-para- phenylenediamine, 2,3-dimethyl-para-phenylenediamine, 2,6-dimethyl- para-phenylenediamine, la 2,6-diethyl-para-phenylenediamine, 2,5- dimethyl-para-phenylenediamine, N,N-dimethyl-para-phenylenediamine, Ν,Ν-diethyl-para-phenylenediamine, N,N-dipropyl-para- phenylenediamine, 4-amino-N,N-diethyl-3-methylaniline, N,N-bis( - hydroxyethyl)-para-phenylenediamine, 4-N,N-bis( -hydroxyethyl)amino- 2-methylaniline, 4-N,N-bis( -hydroxyethyl)amino-2-chloroaniline, 2-β- hydroxyethyl-para-phenylenediamine, 2-fluoro-para-phenylenediamine, 2- isopropyl-para-phenylenediamine, N-( -hydroxypropyl)-para-phenylene- diamine, 2-hydroxymethyl-para-phenylenediamine, N,N-dimethyl-3- methyl-para-phenylenediamine, N-ethyl-N-( -hydroxyethyl)-para- phenylenediamine, N-( ,y-dihydroxypropyl)-para-phenylenediamine, N- (4'-aminophenyl)-para-phenylenediamine, N-phenyl-para-phenylene- diamine, 2- -hydroxyethyloxy-para-phenylenediamine, 2-β- acetylaminoethyloxy-para-phenylenediamine, N-( -methoxyethyl)-para- phenylenediamine, 4-aminophenylpyrrolidine, 2-thienyl-para- phenylenediamine, 2- -hydroxyethylamino-5-aminotoluene, 3-hydroxy- l - (4'-aminophenyl)pyrrolidine and addition salts thereof with an acid. Among the abovementioned para-phenylenediamines, particular preference is given to para-phenylenediamine, para-tolylenediamine, 2- isopropyl-para-phenylenediamine, 2- -hydroxyethyl-para-phenylene- diamine, 2- -hydroxyethyloxy-para-phenylenediamine, 2,6-dimethyl-para- phenylenediamine, 2,6-diethyl-para-phenylenediamine, 2,3-dimethyl-para- phenylenediamine, N,N-bis( -hydroxyethyl)-para-phenylenediamine, 2- chloro -para-phenylenediamine, 2- -acetylaminoethyloxy-para-phenylene- diamine, and addition salts thereof with an acid.

The bisphenylalkylenediamines include, as examples, Ν,Ν'- bis( -hydroxyethyl)-N,N'-bis(4'-aminophenyl)- l ,3 -diaminopropanol, N,N'-bis( -hydroxyethyl)-N,N'-bis(4'-aminophenyl)ethylenediamine, N,N'-bis(4-aminophenyl)tetramethylenedi amine, N,N'-bis( -hydroxy- ethyl)-N,N '-bis (4 -aminophenyl)tetramethylene diamine, N,N'-bis(4- methylaminophenyl)tetramethylenediamine, N,N'-bis(ethyl)-N,N'- bis(4'-amino-3 '-methylphenyl)ethylenediamine, 1 , 8-bis(2,5 -diamino- phenoxy)-3 ,6-dioxaoctane, and addition salts thereof.

The para-aminophenols include, as examples, para- aminopheno l, 4-amino-3 -methylpheno l, 4-amino-3 -fluoropheno l, 4- amino-3 -chlorophenol, 4-amino-3 -hydroxymethylpheno l, 4-amino-2- methylpheno l, 4-amino-2-hydroxymethylpheno l, 4-amino-2- methoxymethylpheno l, 4-amino-2-aminomethylpheno l, 4-amino-2-( - hydroxyethylaminomethyl)phenol, 4-amino-2-fluorophenol, and addition salts thereo f with an acid.

The ortho-aminopheno ls include, as examples, 2-aminophenol, 2-amino-5 -methylpheno l, 2-amino-6-methylpheno l, 5 -acetamido-2- aminopheno l, and addition salts thereo f.

The heterocyclic bases include, as examples, pyridine derivatives, pyrimidine derivatives and pyrazole derivatives.

The pyridine derivatives include the compounds described for example in patents GB 1 026 978 and GB 1 153 196, such as 2,5 - diaminopyridine, 2-(4-methoxyphenyl)amino-3 -aminopyridine and 3 ,4- diaminopyridine, and addition salts thereof.

Other pyridine oxidation bases useful in the present invention are the 3 -aminopyrazolo [ 1 ,5 -a]pyridine oxidation bases or addition salts thereof that are described for example in patent application FR 2801308. Examples include pyrazolo[ 1 ,5-a]pyridin-3-ylamine; 2- acetylaminopyrazolo[ 1 ,5-a]pyridin-3-ylamine; 2-morpholin-4-yl- pyrazolo[ 1 ,5-a]pyridin-3-ylamine; 3-aminopyrazolo[ 1 ,5-a]pyridine-2- carboxylic acid; 2-methoxypyrazolo[l,5-a]pyridin-3-ylamine; (3 aminopyrazolo[ 1 ,5-a]pyridin-7-yl)methanol; 2-(3-aminopyrazolo[ 1 ,5- a]pyridin-5-yl)ethanol; 2-(3-aminopyrazolo[ 1 ,5-a]pyridin-7- yl)ethanol; (3-aminopyrazolo[l,5-a]pyridin-2-yl)methanol; 3,6- diaminopyrazolo[ 1 ,5-a]pyridine; 3,4-diaminopyrazolo[ 1 ,5-a]pyridine; pyrazolo[ 1 ,5-a]pyridine-3,7-diamine; 7-morpholin-4-yl-pyrazolo[l ,5- a]pyridin-3-ylamine; pyrazolo[l,5-a]pyridine-3,5-diamine; 5- morpholin-4-yl-pyrazolo[ 1 ,5-a]pyridin-3-ylamine; 2- [(3 -amino - pyrazolo[ 1 ,5-a]pyridin-5-yl)-(2-hydroxyethyl)amino]ethanol; 2-[(3- aminopyrazolo[ 1 ,5-a]pyridin-7-yl)-(2-hydroxyethyl)amino]ethanol; 3- aminopyrazolo[ 1 ,5-a]pyridin-5-ol; 3-aminopyrazolo[ 1 ,5-a]pyridin-4- ol; 3-aminopyrazolo[l,5-a]pyridin-6-ol; 3-aminopyrazolo[ 1 ,5- a]pyridin-7-ol; and also addition salts thereof.

The pyrimidine derivatives include the compounds described for example in patents DE 2359399; JP 88-169571; JP 05-63124; EP 0770375 or patent application WO 96/15765, such as 2,4,5,6- tetraaminopyrimidine, 4-hydroxy-2,5,6-triaminopyrimidine, 2- hydroxy-4,5,6-triaminopyrimidine, 2,4-dihydroxy-5,6- diaminopyrimidine, 2,5,6-triaminopyrimidine and addition salts thereof and tautomeric forms thereof, when a tautomeric equilibrium exists.

The pyrazole derivatives include the compounds described in patents DE 3843892, DE 4133957 and patent applications WO 94/08969, WO 94/08970, FR-A-2733749 and DE 19543988, such as 4,5-diamino- 1-methylpyrazole, 4,5-diamino- l-( -hydroxyethyl)pyrazole, 3,4- diaminopyrazole, 4,5-diamino- l-(4'-chlorobenzyl)pyrazole, 4,5-diamino- 1 ,3-dimethylpyrazole, 4,5-diamino-3-methyl-l-phenylpyrazole, 4,5- diamino- l-methyl-3-phenylpyrazole, 4-amino-l ,3-dimethyl-5-hydrazino- pyrazole, l-benzyl-4,5-diamino-3-methylpyrazole, 4,5-diamino-3-tert- butyl-l-methylpyrazole, 4,5-diamino- l-tert-butyl-3-methylpyrazole, 4,5- diamino-l-( -hydroxyethyl)-3-methylpyrazole, 4,5-diamino- l-ethyl-3- methylpyrazole, 4,5-diamino- l-ethyl-3-(4'-methoxyphenyl)pyrazole, 4,5- diamino- l-ethyl-3-hydroxymethylpyrazole, 4,5-diamino-3-hydroxymethyl- 1-methylpyrazole, 4,5-diamino-3-hydroxymethyl-l-isopropylpyrazole, 4,5-diamino-3-methyl-l-isopropylpyrazole, 4-amino-5-(2'-aminoethyl)- amino-1 ,3-dimethylpyrazole, 3,4,5-triaminopyrazole, l-methyl-3,4,5- triaminopyrazole, 3,5-diamino-l-methyl-4-methylaminopyrazole, 3,5- diamino-4-( -hydroxyethyl)amino-l-methylpyrazole, and addition salts thereof. Use may also be made of 4,5-diamino- 1-(β- methoxyethyl)pyrazole.

Preference will be given to using a 4,5-diaminopyrazole, and even more preferably 4,5-diamino- 1 -( -hydroxyethyl)pyrazole, and/or one of the salts thereof.

Pyrazole derivatives also include diamino-N,N- dihydropyrazolopyrazolones, and especially those described in patent application FR-A-2 886 136, such as the following compounds and their addition salts: 2,3-diamino-6,7-dihydro-lH,5H-pyrazolo[l,2-a]pyrazol-l- one, 2-amino-3-ethylamino-6,7-dihydro- 1 H,5H-pyrazolo[ 1 ,2-a]pyrazol- 1 - one, 2-amino-3-isopropylamino-6,7-dihydro-lH,5H-pyrazolo[l,2-a]- pyrazol- 1 -one, 2-amino-3-(pyrrolidin- 1 -yl)-6,7-dihydro- 1 H,5H-pyrazolo- [ 1 ,2-a]pyrazol- 1 -one, 4,5-diamino- 1 ,2-dimethyl- 1 ,2-dihydro-pyrazol-3- one, 4,5-diamino- 1 ,2-diethyl- 1 ,2-dihydro-pyrazol-3-one, 4,5-diamino- 1 ,2- di-(2-hydroxyethyl)-l ,2-dihydro-pyrazol-3-one, 2-amino-3-(2-hydroxy- ethyl)amino-6,7-dihydro-lH,5H-pyrazolo[l ,2-a]pyrazol-l-one, 2-amino-3- dimethylamino-6,7-dihydro- 1 H,5H-pyrazolo [ 1 ,2-a]pyrazol- 1 -one, 2,3- diamino-5 ,6,7,8-tetrahydro- 1 H,6H-pyridazino[ 1 ,2-a]pyrazol- 1 -one, 4- amino- 1 ,2-diethyl-5-(pyrrolidin- 1 -yl)- 1 ,2-dihydro-pyrazol-3-one, 4- amino-5-(3-dimethylamino-pyrrolidin- 1 -yl)- 1 ,2-diethyl- 1 ,2-dihydro- pyrazol-3-one, 2,3-diamino-6-hydroxy-6,7-dihydro-lH,5H-pyrazolo[l,2- a]pyrazol-l-one.

Preference will be given to using 2,3-diamino-6,7-dihydro- lH,5H-pyrazolo[l,2-a]pyrazol-l-one and/or a salt thereof. Heterocyclic bases which will be used are preferably 4,5 - diamino- 1 - ( -hydroxyethyl)pyrazo le and/or 2,3 -diamino-6,7-dihydro- l H,5H-pyrazolo [ l ,2-a]pyrazol- l -one and/or a salt thereo f.

The composition according to the invention may optionally comprise one or more couplers advantageously chosen from those conventionally used in the dyeing o f keratin fibres .

Mention may in particular be made, among these couplers, of meta-phenylenediamines, meta-aminopheno ls, meta-dipheno ls, naphthalene-based couplers and heterocyclic couplers, and also the addition salts thereo f.

Examples include 1 ,3-dihydroxybenzene, 1 ,3-dihydroxy-2- methylbenzene, 4-chloro- l ,3-dihydroxybenzene, 2,4-diamino- l -(B- hydroxyethyloxy)benzene, 2-amino-4-(B-hydroxyethylamino)- 1 - methoxybenzene, 1 ,3-diaminobenzene, 1 ,3-bis(2,4-diaminophenoxy)- propane, 3-ureidoaniline, 3-ureido- l -dimethylaminobenzene, sesamol, 1 - B-hydroxyethylamino-3 ,4-methylenedioxybenzene, cc-naphthol, 2-methyl- 1 -naphthol, 6-hydroxyindole, 4-hydroxyindole, 4-hydroxy-N- methylindole, 2-amino-3-hydroxypyridine, 6-hydroxybenzomorpholine, 3 ,5-diamino-2,6-dimethoxypyridine, l -N-(B-hydroxyethyl)amino-3 ,4- methylenedioxybenzene, 2,6-bis(B-hydroxyethylamino)toluene, 6- hydroxyindoline, 2,6-dihydroxy-4-methylpyridine, l H-3-methylpyrazol-5- one, l -phenyl-3-methylpyrazol-5-one, 2,6-dimethylpyrazolo[ l ,5-b]- l ,2,4- triazole, 2,6-dimethyl[3 ,2-c]- 1 ,2,4-triazole, 6-methylpyrazolo[ 1 ,5- ajbenzimidazole, addition salts thereof with an acid, and mixtures thereof.

Generally speaking, the addition salts of the oxidation bases and the couplers that can be used in the context of the invention are chosen in particular from addition salts with an acid such as hydrochlorides, hydrobromides, sulfates, citrates, succinates, tartrates, lactates, tosylates, benzenesulfonates, phosphates and acetates .

The oxidation dye or dyes represent advantageously from

0.001 % to 10% by weight, and preferably from 0.05 % to 5 % by weight, relative to the total weight of the composition comprising it or them. The synthetic direct dyes are more particularly chosen from ionic or nonionic species, preferably cationic or nonionic species.

A synthetic direct dye is any direct dye which does not exist in the natural state, including the dyes obtained from semi-synthesis.

Examples of suitable synthetic direct dyes include direct azo, methine, carbonyl, azine, (hetero)aryl nitro, tri(hetero)arylmethane, porphyrin and phthalocyanine dyes, alone or as mixtures.

The synthetic direct azo dyes more particularly include a -N=N- function in which the two nitrogen atoms are not simultaneously part of a ring system. This does not, however, rule out one of the two nitrogen atoms of the -N=N- sequence forming part of a ring system.

The direct dyes from the class of the methines are more particularly compounds comprising at least one sequence chosen from >C=C< and -N=C< in which the two atoms do not simultaneously form part of a ring system. It is, however, specified that one of the nitrogen or carbon atoms in the sequences may form part of a ring system.

The methine dyes are more particularly obtained from methine, azomethine, hydrazono, mono- and diarylmethane, indoamine (or diphenylamine), indophenol, indoaniline and (hemi)cyanin compounds, such as styryl, streptocyanin, carbocyanin, azacarbocyanin, diazacarbocyanin and tetraazacarbocyanin dyes, and optical and geometric isomers thereof.

Examples of synthetic direct dyes from the class of the carbonyls include the dyes chosen from acridone, benzoquinone, anthraquinone, naphthoquinone, benzanthrone, anthanthrone, pyranthrone, pyrazolanthrone, pyrimidinoanthrone, flavanthrone, indanthrone, flavone, (iso)violanthrone, isoindolinone, benzimidazolone, isoquinolinone, anthrapyridone, pyrazoloquinazolone, perinone, quinacridone, quinophthalone, indigoid, thioindigo, naphthalimide, anthrapyrimidine, diketopyrrolopyrrole and coumarin dyes.

The synthetic direct dyes from the class of the cyclic azines include, in particular, azine, xanthene, thioxanthene, fluorindine, acridine, (di)oxazine, (di)thiazine and pyronine dyes . Synthetic (hetero)aromatic nitro direct dyes are more particularly nitrobenzene or nitropyridine direct dyes .

Concerning the (metallo)porphyrin or phthalocyanine synthetic direct dyes, use may be made of cationic or non-cationic compounds, optionally comprising one or more metals or metal ions, such as, for example, alkali metals and alkaline earth metals, zinc and silicon.

Examples of particularly suitable synthetic direct dyes include the nitro dyes from the benzene series; direct azo, methine, azomethine, hydrazono or styryl dyes; azacarbocyanin dyes such as tetraazacarbocyanins (tetraazapentamethines); direct quinone dyes and more particularly anthraquinone, naphthoquinone or benzoquinone dyes; direct azine, xanthene, triarylmethane, indoamine, indigoid, phthalocyanine and porphyrin dyes, alone or as mixtures.

These dyes may be monochromophoric dyes (meaning that they comprise only one dye) or polychromophoric dyes, preferably di- or trichromophoric dyes; the chromophores may be identical or different, from the same chemical class or a different class . It should be noted that a polychromophoric dye comprises a number of groups each obtained from a mo lecule which absorbs in the visible range between 400 and 800 nm. Furthermore, this absorbance by the dye does not require any prior oxidation thereof, or combination with any other chemical species .

In the case o f po lychromophoric dyes, the chromophores are connected to one another via at least one linker L, which may be cationic or non-cationic.

The linker L is preferably a linear, branched or cyclic C ₁ -C₂₀ alkyl chain, which is optionally interrupted and/or terminated by at least i) one heteroatom (such as nitrogen N(R), N⁺R,R' , Q^", oxygen or sulfur), ii) one group C(O), C(S), S(O), S(0)₂, or iii) one combination thereo f, optionally interrupted by at least one heterocycle that is or is not fused with a phenyl ring and comprising at least one quaternized nitrogen atom forming part of said cyclic system, and optionally at least one other heteroatom (such as oxygen, nitrogen or sulfur), optionally interrupted by at least one substituted or unsubstituted phenyl or naphthyl group, optionally at least one quaternary ammonium group substituted by two C1-C15 alkyl groups which are optionally substituted; the linker does not include a nitro, nitroso or peroxo group, and R and R', which are identical or different, represent a hydrogen atom or a Ci-C₆ alkyl group which is optionally substituted, preferably by at least one hydroxyl group, and Q^" represents an organic or inorganic anionic counter-ion such as a halide or an alkyl sulfate.

If the heterocycles or aromatic nuclei are substituted, the substituents are, for example, one or more Ci-Cs alkyl groups which are optionally substituted by a hydroxyl, C1-C2 alkoxy, C2-C4 hydroxyalkoxy, acetylamino or amino group substituted by one or two C1-C4 alkyl groups, which optionally carry at least one hydroxyl group, or the two groups may form, together with the nitrogen atom to which they are attached, a 5- or 6-membered heterocycle, optionally comprising another heteroatom identical to or different from nitrogen; a halogen atom; a hydroxyl group; a C1-C2 alkoxy group; a C2-C4 hydroxyalkoxy group; an amino group; an amino group substituted by one or two identical or different C1-C4 alkyl groups which optionally carry at least one hydroxyl group.

Among the nitrobenzene direct dyes that may be used according to the invention, mention may be made in a nonlimiting manner of the following compounds:

- 1 ,4-diamino-2-nitrobenzene,

- 1 -amino-2-nitro-4-B-hydroxyethylaminobenzene

- 1 - amino -2 -nitro -4 -bis( - hydroxy ethyl) aminobenzene

- 1 ,4-bis(B-hydroxyethylamino)-2-nitrobenzene

- 1 -B -hydro xyethylamino -2-nitro -4-bis-( - hydroxyethylamino)benzene

- 1 -B-hydroxyethylamino-2-nitro-4-aminobenzene

- 1 - β -hydroxy ethylamino -2 -nitro -4 -(ethyl) (fitly droxy ethyl) aminobenzene

- 1 - amino-3-methyl-4- -hydroxyethylamino-6-nitrobenzene

- 1 - amino-2-nitro-4- -hydroxyethylamino-5-chlorobenzene - 1 ,2-diamino-4-nitrobenzene

- 1 - amino -2- β -hydro xyethylamino- 5 -nitrobenzene

- 1 ,2-bis-( -hydroxyethylamino)-4-nitrobenzene

- 1 -amino-2-tris-(hydroxymethyl)-methylamino-5 - nitrobenzene

- 1 -hydro xy-2- amino -5 -nitrobenzene

- 1 -hydroxy-2-amino-4-nitrobenzene

- 1 -hydroxy- 3 -nitro -4 -amino benzene

- 1 -hydro xy-2 -amino -4, 6 -dinitrobenzene

- 1 - -hydroxyethyloxy-2- -hydroxyethylamino-5 -nitrobenzene

- 1 -methoxy-2- -hydroxyethylamino-5 -nitrobenzene

- 1 - -hydroxyethyloxy-3 -methylamino-4-nitrobenzene

- 1 - ,y-dihydroxypropyloxy-3 -methylamino-4-nitrobenzene

- 1 - -hydroxyethylamino-4- ,y-dihydroxypropyloxy-2- nitrobenzene

- 1 - ,y-dihydroxypropylamino-4-trifluoromethyl-2- nitrobenzene

- 1 - -hydroxyethylamino-4-trifluoromethyl-2-nitrobenzene

- 1 - -hydroxyethylamino-3 -methyl-2-nitrobenzene

- 1 - -amino ethylamino-5 -methoxy-2-nitrobenzene

- 1 -hydro xy-2-chloro-6-ethylamino-4-nitrobenzene

- 1 -hydro xy-2-chloro-6-amino-4-nitrobenzene

- 1 -hydro xy-6-bis-( -hydroxyethyl)-amino- 3 -nitrobenzene

- 1 - -hydroxyethylamino-2-nitrobenzene

- 1 -hydroxy-4- -hydroxyethylamino-3 -nitrobenzene.

The direct azo , azomethine, methine or tetraazapentamethine dyes which can be used according to the invention include the cationic dyes described in patent applications WO 95/15 144, WO 95/0 1772 and EP 714954; FR 21 89006 , FR 228585 1 , FR 2140205 , EP 1378544, EP 1674073.

According to one particularly advantageous embodiment of the invention, the dye or dyes are selected from (poly)azo dyes such as (dis)azo dyes, hydrazono dyes, (poly)methine dyes such as styryl dyes, anthraquinone dyes or naphthalimide dyes. These dyes are preferably (poly)cationic.

According to one preferred embodiment of the invention, the dyes are chosen from the cationic dyes referred to as "basic dyes".

Mention may be made of the following cationic hydrozono dyes of formula (la) and (I'a), azo dyes (Ha) and (H'a) and disazo dyes (Ilia):

a

and in these formulae (la), (I'a), (Ila), (H'a) and (Ilia):

- Het⁺ represents a cationic heteroaryl group, preferably having an endocyclic cationic charge, such as imidazolium, indolium, or pyridinium, which is optionally substituted preferably by one or more Ci-Cs alkyl groups such as methyl;

- Ar⁺ represents an aryl group, such as phenyl or naphthyl, having an exocyclic cationic charge, preferably ammonium, particularly tri(Ci- C8 alkyl)ammonium such as trimethylammonium;

- Ar represents an aryl group, in particular phenyl, which is optionally substituted, preferably by one or more electron-donating groups such as i) optionally substituted Ci-Cs alkyl, ii) optionally substituted Ci-Cs alkoxy, iii) (di)(Ci-Cs alkyl)amino optionally substituted on the alkyl group or groups by a hydroxyl group, iv) aryl(Ci-C₈ alkyl)amino, v) N-(d-Cs alkyl)-N-aryl(Ci-C₈ alkyl)amino which is optionally substituted, or else Ar represents a julolidine group;

- Ar' is an optionally substituted divalent (hetero)arylene group such as phenylene, particularly para-phenylene, or naphthalene, which are optionally substituted, preferably by one or more Ci-Cs alkyl, hydroxyl or Ci-Cs alkoxy groups;

- Ar" is an optionally substituted (hetero)aryl group such as phenyl or pyrazolyl which are optionally substituted, preferably by one or more Ci-Cs alkyl, hydroxyl, (di)(Ci-Cs alkyl)amino, Ci-Cs alkoxy or phenyl groups;

- R^a and R^b, which are identical or different, represent a hydrogen atom or a Ci-Cs alkyl group which is optionally substituted, preferably by a hydroxyl group;

or else the substituent R^a with a substituent of het⁺ and/or R^b with a substituent of Ar, form, together with the atoms which carry them, a (hetero)cycloalkyl;

in particular, R^a and R^b, represent a hydrogen atom or a C₁-C4 alkyl group which is optionally substituted by a hydroxyl group;

- Q^" represents an organic or inorganic anionic counter-ion such as a halide or an alkyl sulfate.

In particular, the dyes of the invention are endocyclic cationic- charge azo and hydrazono dyes of formulae (la), (I 'a) and (Ha) as defined above. More particular preference is given to those of formulae (la), (I'a) and (Ha) that are described in patent applications WO 95/15144, WO 95/01772 and EP-714954. Dyes of the invention are preferably chosen from the following compounds:

and in these formulae (Ia-1) and (IIa-1):

- R¹ represents a C₁-C4 alkyl group such as methyl;

- R² and R³, which are identical or different, represent a hydrogen atom or a C₁-C4 alkyl group such as methyl; and - R⁴ represents a hydrogen atom or an electron-donating group such as optionally substituted Ci-Cs alkyl, optionally substituted Ci-Cs alkoxy, and (di)(Ci-Cs alkyl)amino which is optionally substituted on the alkyl group or groups by a hydroxyl group; in particular, R⁴ is a hydrogen atom,

- Z represents a CH group or a nitrogen atom, preferably CH,

- Q^" is as defined before.

The dyes of formula (Ia-1) and (IIa-1) are chosen in particular from Basic Red 51, Basic Yellow 87 and Basic Orange 31 or derivatives thereof:

where Q^" is as defined before, and represents in particular a halide such as a chloride, or an alkyl sulfate such as methyl sulfate or mesityl.

Mention may also be made, among the direct azo dyes, of the following dyes, which are described in the 3^rd edition of Colour Index International:

- Disperse Red 17

- Basic Red 22

- Basic Red 76

- Basic Yellow 57

- Basic Brown 16

- Basic Brown 17 - Disperse Black 9.

Mention may also be made of l-(4'-aminodiphenylazo)-2- methy 1-4 -bis( -hydroxyethyl)amino benzene.

Among the quinone direct dyes, mention may be made of the following dyes:

- Disperse Red 15

- Solvent Violet 13

- Disperse Violet 1

- Disperse Violet 4

- Disperse Blue 1

- Disperse Violet 8

- Disperse Blue 3

- Disperse Red 11

- Disperse Blue 7

- Basic Blue 22

- Disperse Violet 15

- Basic Blue 99

and also the following compounds:

- 1 -N-methylmorpholiniumpropylamino-4-hydroxyanthraquinone - 1 -aminopropylamino-4-methylaminoanthraquinone

- 1 -aminopropylaminoanthraquinone;

- 5" -hydroxyethyl- 1 ,4-diaminoanthraquinone;

- 2-aminoethylaminoanthraquinone; and

- 1 ,4-bis( ,y-dihydroxypropylamino)anthraquinone.

Among the azine dyes, mention may be made of the following compounds:

- Basic Blue 17

- Basic Red 2.

Among the triarylmethane dyes that can be used according to the invention, mention may be made of the following compounds:

- Basic Green 1

- Basic Violet 3

- Basic Violet 14

- Basic Blue 7 - Basic Blue 26.

Among the indoamine dyes that may be used according to the invention, mention may be made of the following compounds:

- 2- -hydroxyethlyamino-5-[bis( -4'- hydroxyethyl)amino]anilino- 1 ,4-benzoquinone

- 2- -hydroxyethylamino-5-(2'-methoxy-4 '- amino) anilino- 1 ,4- benzoquinone

- 3-N-(2'-chloro-4'-hydroxy)phenylacetylamino-6-methoxy- 1 ,4-benzoquinone imine

- 3-N-(3'-chloro-4'-methylamino)phenylureido-6-methyl-l,4- benzoquinone imine

- 3-[4'-N-ethyl-N-carbamylmethylamino]phenylureido-6- methyl- 1 ,4-benzoquinone imine.

The tetraazapentamethine dyes that can be used according to the invention include the following compounds appearing in the table below:

where X represents an anion chosen preferably from chloride, iodide, methyl sulfate, ethyl sulfate, acetate and perchlorate.

The po lychromophoric dyes include more particularly the symmetrical or non-symmetrical di- or tri-chromophoric azo and/or azomethine (hydrazone) dyes, comprising on the one hand at least one 5 - or 6-membered aromatic heterocycle, optionally fused, which comprises at least one quaternized nitrogen atom forming part of said heterocycle, and optionally at least one other heteroatom (such as nitrogen, sulfur or oxygen), and, on the other hand, at least one optionally substituted phenyl or naphthyl group which optionally carries at least one group OR in which R represents a hydrogen atom, an optionally substituted C i -C₆ alkyl group, an optionally substituted phenyl nucleus, or at least one group N(R' )₂ , in which R' , identical or different, represents a hydrogen atom, an optionally substituted C i -C₆ alkyl group or an optionally substituted phenyl nucleus; with the nitrogen atom to which they are bonded, the groups R' may form a saturated, 5 - or 6-membered heterocycle, or else one and/or both of the groups R' may each form a saturated, 5 - or 6-membered heterocycle with the carbon atom o f the aromatic ring system that is situated ortho to the nitrogen atom.

Aromatic cationic heterocycles that may preferably be mentioned include 5 - or 6-membered rings containing 1 to 3 nitrogen atoms and preferably 1 or 2 nitrogen atoms, one being quaternized; said heterocycle moreover being optionally fused to a benzene nucleus. It should similarly be noted that the heterocycle may optionally comprise another heteroatom other than nitrogen, for instance sulfur or oxygen.

If the heterocycles or phenyl or naphthyl groups are substituted, the substituents are, for example, one or more Ci-Cs alkyl groups optionally substituted by a hydroxyl group, Ci-C₂ alkoxy, C₂- C₄ hydroalkoxy, acetylamino, amino-substituted by one or two Ci-C₄ alkyl groups, which optionally carry at least one hydroxyl group, or the two groups, with the nitrogen atom to which they are attached, may form a 5- or 6-membered heterocycle, optionally comprising another heteroatom identical to or different from nitrogen; a halogen atom; a hydroxyl group; a Ci-C₂ alkoxy group; a C₂-C₄ hydroxyalkoxy group; an amino group; an amino group substituted by one or two identical or different Ci-C₄ alkyl groups which optionally carry at least one hydroxyl group.

These polychromophores are joined to one another by at least one linker L as defined before.

The linkage between the linker L and each chromophore is generally made by means of a heteroatom substituting the phenyl or naphthyl nucleus or by means of the quaternized nitrogen atom of the cationic heterocycle.

The dye may comprise identical or different chromophores. As examples of such dyes, reference may be made especially to patent applications EP 1 637 566, EP 1 619 221, EP 1 634 926, EP 1 619220, EP 1 672033, EP 1 671 954, EP 1 671 955, EP 1 679 312, EP 1 671 951, EP 167 952, EP 167 971, WO 06/063 866, WO 06/063 867, WO 06/063 868, WO 06/063 869, EP 1 408 919, EP 1 377 264, EP 1 377262, EP 1 377261, EP 1 377263, EP 1 399425, EP 1 399 117, EP 1 416909, EP 1 399 116 and EP 1 671 560.

It is also possible to employ cationic synthetic direct dyes as cited in the following patent applications: EP 1006153, which describes dyes comprising two anthraquinone chromophores connected via a cationic linker; EP 1433472, EP 1433474, EP 1433471 and EP 1433473, which describe identical or non-identical dichromophoric dyes, connected by a cationic or non-cationic linker; and EP 6291333 , which describes, in particular, dyes comprising three chromophores, one o f them being an anthraquinone chromophore, to which two chromophores of azo or diazacarbocyanine type, or an isomer thereof, are connected.

When present, the synthetic direct dye or dyes may be present in an amount of from 0.01 % to 20% by weight, preferably from 0. 1 % to 1 0%) by weight, and more preferably 0.2%> to 5 % by weight, relative to the total weight of the composition comprising it or them.

By natural dyes are meant any dye or dye precursor that occurs naturally and that is produced either by extraction (and, where appropriate, purification) from an animal or plant matrix, optionally in the presence of natural compounds such as ash or ammonia, or by chemical synthesis.

Natural dyes include lawsone and henna, curcumin, chlorophylline, alizarin, kermesic acid, purpurin, purporogallin, indigo, Tyrian purple, sorgum, carminic acid, catechin, epicatechin, juglone, bixin, betanin, quercetin, chromene dyes and chroman dyes, including haematin, brazileine, haematoxylin and brazilin, and laccaic acids .

Preferably, the natural dyes used in the invention are chosen from curcumin, chlorophylline, chromene dyes, chroman dyes and laccaic acids.

By chromene or chroman dye is meant, according to the invention, dyes which comprise in their structure at least one bicyclic system of formula (K) below:

K where the endocyclic bond represents a carbon-carbon single bond or a carbon-carbon double bond, as illustrated by formula Kl , denoting the class of the chromenes, and formula K2, denoting the class o f the chromans, below:

More particularly, the dyes which in their structure have a bicyclic system o f formula (K) are chosen from the dyes o f the fo llowing formulae :

- formula (V), comprising in its structure the bicyclic system o f formula K2,

in which:

represents a carbon-carbon single bond or a carbon- carbon double bond, the chain sequence of these bonds denotes two carbon-carbon single bonds and two carbon-carbon double bonds, said bonds being conjugated,

X represents a group :

// /

H O— C or 0=C

\ \

R¹ , R², R³ , R⁴, R⁵ and R⁶, which are identical or different, represent independently of one another a hydrogen atom, a hydroxyl group, an optionally substituted alkyl or optionally substituted alkoxy group, or an optionally substituted acyloxy group,

and also the tautomeric and/or mesomeric forms thereof, the stereoisomers thereof, the addition salts thereof with a cosmetically acceptable acid or base, and the hydrates thereof, and

- formula (VI), comprising its structure the bicyclic system of formula Kl :

in which:

- Rii, Ri2, Ri3, Ri6, Ri and R₂o, which are identical or different, represent, independently of one another, a hydrogen atom or a C1-C4 alkyl group,

- Ri4, Ri5, Ri7 and Ris, which are identical or different, represent, independently of one another, a hydrogen atom, a hydroxyl group or a C1-C4 alkoxy group,

and also the tautomeric and/or mesomeric forms thereof, the stereoisomers thereof, the addition salts thereof with a cosmetically acceptable acid or base, and the hydrates thereof.

The dyes of formula (V) as defined above may be in two tautomeric forms (Va) and (Vb):

The alkyl groups cited in the above definitions of the substituents are generally C₁-C₂₀, particularly Ci-Cio, preferably Ci- C₆, linear or branched, saturated hydrocarbon groups, such as methyl, ethyl, propyl, butyl, pentyl and hexyl.

The alkoxy groups are alkyl-oxy groups with the alkyl groups as defined above, and the alkoxy groups are preferably Ci-Cio groups, such as methoxy, ethoxy, propoxy and butoxy.

When they are substituted, the alkyl or alkoxy groups may be substituted by at least one substituent carried by at least one carbon atom and chosen from:

- a halogen atom;

- a hydroxyl group;

- a C1-C2 alkoxy group;

- a C1-C10 alkoxycarbonyl group;

- a C2-C4 (poly)hydroxyalkoxy group;

- an amino group;

- a 5- or 6-membered heterocycloalkyl group;

- a 5- or 6-membered heteroaryl group, optionally cationic, preferably imidazolium, which is optionally substituted by a (Ci- C₄)alkyl group, preferably methyl;

- an amino group substituted by one or two identical or different Ci-C₆ alkyl groups which optionally carry at least:

* one hydroxyl group,

* one amino group optionally substituted by one or two optionally substituted C1-C3 alkyl groups, the said alkyl groups being able, with the nitrogen atom to which they are attached, to form a saturated or unsaturated, optionally substituted, 5 - to 7-membered heterocycle optionally comprising at least one other heteroatom identical to or different from nitrogen,

* a quaternary ammonium group -N R' R"R' " , M^", for which R' , R" and R' " , which are identical or different, represent a hydrogen atom or a C ₁ -C₄ alkyl group, and M^" represents the counter-ion o f the organic or inorganic acid or of the corresponding halide,

* or one optionally cationic 5 - or 6-membered heteroaryl group, preferably imidazolium, which is optionally substituted by a (C ₁ -C₄) alkyl group, preferably methyl;

- an acylamino group (-NR-COR' ) in which the group R is a hydrogen atom, a C ₁ -C₄ alkyl group optionally carrying at least one hydroxyl group, and the group R' is a C ₁ - C₂ alkyl group;

- a carbamoyl group ((R)₂N-CO-) in which the groups R, which are identical or different, represent a hydrogen atom or a C ₁ -C₄ alkyl group optionally carrying at least one hydroxyl group;

- an alkylsulfonylamino group (R' S0₂-NR-) in which the group R represents a hydrogen atom or a C ₁ -C₄ alkyl group which optionally carries at least one hydroxyl group, and the group R' represents a C ₁ -C₄ alkyl group or a phenyl group;

- an amino sulfonyl group ((R)₂N-S0₂-) in which the groups R, which are identical or different, represent a hydrogen atom or a C ₁ -C₄ alkyl group which optionally carries at least one hydroxyl group,

- a carboxyl group in acid or salified form (preferably with an alkali metal or a substituted or unsubstituted ammonium);

- a cyano group;

- a nitro group;

- a carboxyl or glycosylcarbonyl group;

- a phenylcarbonyloxy group optionally substituted by one or more hydroxyl groups;

- a glyco syloxy group; and

- a phenyl group optionally substituted by one or more hydroxyl groups. A glyco syl group is a group originating from a mono- or polysaccharide.

The alkyl or alkoxy groups of the formula (V) are preferably not substituted.

According to one particular embodiment of the invention, the dyes of formula (V) comprise a group R⁶ which represents a hydroxyl group .

Another particular embodiment of the invention relates to the dyes o f formula (V) for which the group R¹ represents a hydrogen atom or a hydroxyl group .

More preferably, the dyes of formula (V) are chosen from haematoxylin, haematin, brazilin and brazileine.

Brazileine is a conjugated form of a chroman compound o f formula K2. The scheme below shows the tautomeric structures (Va) and (Vb) illustrated above.

Brazileine

Among the haematoxylin/haematin and brazilin/brazileine dyes, examples that may be mentioned include haematoxylin (Natural Black 1 according to the INCI name) and brazilin (Natural Red 24 according to the INCI name), dyes of the indochroman family, which are commercially available. The latter dyes may exist in an oxidized form and may be obtained synthetically or by extraction o f plants or vegetables known to be rich in these dyes.

The dyes o f formula (V) may be used in the form o f extracts .

Use may be made of the fo llowing plant extracts (genus and species) : Haematoxylon campechianum, Haematoxylon brasiletto, Caesalpinia echinata, Caesalpinia sappan, Caesalpinia spinosa, and Caesalpinia brasiliensis.

The extracts are obtained by extracting the various plant parts, for instance the root, the wood, the bark or the leaves .

According to one particular embodiment of the invention, the natural dyes of formula (V) are obtained from logwood, pernambuco wood, sappan wood and Brazil wood.

The salts o f the dyes of formula (V) and (VI) of the invention may be salts o f cosmetically acceptable acids or bases.

The acids may be inorganic or organic. Preferably, the acid is hydrochloric acid, which results in chlorides.

The bases can be inorganic or organic. In particular, the bases are alkali metal hydroxides such as sodium hydroxide, which leads to sodium salts.

The dye or dyes o f formula (V) and (VI) included in the composition according to the invention are preferably obtained from plant extracts. Use may also be made of mixtures o f plant extracts . The natural extracts of dyes according to the invention may be in the form o f powders or liquids . Preferably, the extracts are in powder form.

In another variant of the invention, the natural dyes are chosen from laccaic acids.

For the purposes of the present invention, the term " laccaic acid" means a compound having in its structure a unit of the type:

The laccaic acids of the invention are preferably of formula (VII) below :

(VII)

where Ri denotes a phenyl group substituted by at least one hydroxyl group, and preferably by a hydroxyl group which is located advantageously in a position ortho to the bond attaching it to the fused nuclei.

In particular, the phenyl group of Ri comprises not only a hydroxyl group but also at least one group -CH2R2 , where R₂ denotes an acetamideomethyl (CH₃CONHCH₂-), hydroxymethyl (HOCH₂-) or 2-aminoacetic acid (H0₂C(NH₂)CH-) group .

The laccaic acids of the invention are preferably chosen from laccaic acids A, B, C and D or mixtures thereof, and more particularly are chosen from A, B or C, or mixtures thereof.

A laccaic acid according to the invention that may especially be used is the dye CI Natural Red 25 , CI 75450, CAS - 60687-93 -6 , which is o ften referred to as laccaic acid. This is a dye o f natural origin that originates from the secretions of an insect, Coccus laccae (Lacifer Lacca Kerr), which is generally found on the twigs o f certain trees native to South-East Asia.

CI Natural Red 25 generally contains two major constituents in its composition: laccaic acid A and laccaic acid B . It may also contain a small amount of laccaic acid C .

It is o f course also possible to use the purified forms of the laccaic acids of formula (VII) .

The natural direct dyes are preferably chosen from haematoxylin, haematein, brazileine, brazilin and mixtures thereof.

Even more preferentially, the natural dyes are chosen from haematin and brazileine.

When present, the natural dye or dyes may be present in an amount of from 0.05 % to 60% by weight, preferably from 0. 1 % to 20% by weight and more preferably from 0.2% to 10% by weight, relative to the total weight of the composition comprising it or them. In one particular embodiment, the dye or dyes used in the method of the invention are chosen from synthetic direct dyes and natural dyes, and more particularly from the natural dyes as described above . More particularly, use is made of the natural dyes of formula (V), such as haematoxylin, haematein, brazilin and brazileine, and especially those obtained from logwood.

The compositions comprising the chaotropic salt or salts and/or the dye or dyes that are used in the invention may further comprise one or more clays .

More particularly, the clays that are of interest for the invention are clays chosen from montmorillonites, attapulgites, bentonites, vermiculites, goethites, hydroxyapatites, Laponites and hydrotalcite.

Also comprehended by clay according to the invention are the fo llowing :

• mixtures of clays, especially natural mixtures, also called layer-to-layer mixtures, such as illite-smectite, illite-chlorite, smectite-chlorite, vermiculite-illite and smectite-kao linite mixtures, and

· modified clays, which are clays which have undergone chemical modification and are not found in this form in the natural state. These mo difications may be obtained by physical (temperature) or chemical processes (addition o f a neutralizing counter-ion such as organic or inorganic acids or bases, by ion exchange, by addition o f a polymerizable or non-polymerizable cationic or anionic surfactant, or else a natural or synthetic po lymer) . Modified clays which may be mentioned in particular include Bentones such as stearalkonium hectorite and stearalkonium bentonite .

The compositions used in the invention preferably comprise modified clays, for instance Bentones, such as stearalkonium hectorite and stearalkonium bentonite .

The compositions comprising the chaotropic salt or salts and/or the dye or dyes generally comprise water or a mixture of water and one or more organic so lvents. The organic solvents include more particularly non-aromatic alcoho ls such as ethanol, isopropanol, or glycols or glycol ethers such as for example, ethylene glycol monomethyl, monoethyl and monobutyl ethers, propylene glycol or its ethers such as, for example propylene glyco l monoethyl ether, butylene glyco l, dipropylene glycol, and also diethylene glycol alkyl ethers such as, for example diethylene glyco l monoethyl ether or monobutyl ether, or else po lyo ls such as glycerol, or else aromatic alcoho ls such as benzyl alcohol, phenylpropanol and phenylethano l. Polyethylene glyco ls and polypropylene glycols, and mixtures of all these compounds, may also be used as so lvent.

The organic solvents are preferably chosen from ethano l, benzyl alcoho l and mixtures thereof.

The organic so lvents, if present, represent, usually from 0. 1 % to 25 % by weight, more preferably from 1 % to 20% by weight, relative to the total weight of the composition comprising the chaotropic salt or salts and/or the dye or dyes.

The amount of water is preferably from 1 5 % to 90% by weight, more preferably from 50% to 85 % by weight, relative to the total weight of the composition.

The method according to the invention may further employ one or more chemical oxidizing agents. According to one particular embodiment of the invention, the method does not employ a chemical oxidizing agent.

A "chemical oxidizing agent" according to the invention is any oxidizing agent other than atmospheric oxygen. The chemical oxidizing agent or agents are chosen more particularly from hydrogen peroxide, urea peroxide, alkali metal bromides or ferricyanides, peroxygenated salts such as, for example, persulfates, perborates and percarbonates of alkali or alkaline earth metals, and also peracids and precursors thereof. As a chemical oxidizing agent it is additionally possible to use one or more redox enzymes such as laccases, peroxidases and oxidoreductases having two electrons (such as uricase), optionally in the presence of their respective donor or cofactor.

The pH of the composition or compositions according to the invention is generally from 2.5 to about 11, and preferably from 2.7 to about 10.

It may be adjusted to the desired value by means of acidifying or basifying agents.

Among the acidifying agents, mention may be made, by way of example, of inorganic or organic acids, for instance hydrochloric acid, orthophosphoric acid, sulfuric acid, carboxylic acids, for instance acetic acid, tartaric acid, citric acid and lactic acid, and sulfonic acids.

Among the basifying agents, mention may be made, by way of example, of aqueous ammonia, alkali metal carbonates, alcanolamines such as mono-, di- and triethanolamines and derivatives thereof, sodium hydroxide or potassium hydroxide, and the compounds of formula (VIII) below:

^R1 \ / ^R3

N-W-N

^R2 R₄

⁴ (VIII)

W in this formula (VIII) being a linear or branched Ci-C₆ alkylene residue such as propylene, which is optionally substituted by one or more hydroxyl groups, or amino NRiR₂; Ri, R₂, R3 and R₄, which are identical or different, represent a hydrogen atom or a Ci-C₆ alkyl or Ci-C₆ hydroxyalkyl group.

The cosmetic compositions in accordance with the invention may further comprise one or more cosmetic adjuvants.

The cosmetic adjuvant or adjuvants may be chosen from those conventionally used in cosmetic compositions, particularly for dying human keratin fibres, and more particularly from anionic, cationic, nonionic, amphoteric and zwitterionic polymers or mixtures thereof; anionic, nonionic, cationic or amphoteric surfactants; pigments; thickeners; antioxidants; sequestrants; fragrances; buffers; dispersants; modified or non-modified, vo latile or non-vo latile silicones; film formers; ceramides; preservatives; stabilizers; and opacifiers .

Of course, those skilled in the art will take care to select this or these optional additional compound(s) such that the advantageous properties intrinsically associated with the composition in accordance with the invention are not, or are not substantially, adversely affected by the envisaged addition(s) .

The above adjuvants are generally present in an amount, for each o f them, of between 0% and 20% by weight, relative to the total weight of the composition.

The composition or compositions of the invention employed in the dyeing method may be present in a variety o f forms, such as in the form o f liquids, shampoos, creams, gels, or any other appropriate form.

According to a first embodiment of the invention, the method comprises the fo llowing steps :

(i) the application to the keratin fibres of a composition comprising one or more chaotropic salts in an amount of from 50% to 90% by weight relative to the total weight of the composition, and one or more dyes, and

(ii) rinsing.

According to another particular embodiment of the invention, the method comprises the fo llowing steps :

(i') the application to the keratin fibres of a composition comprising one or more chaotropic salts in an amount of from 50% to 90% by weight relative to the total weight of the composition,

(ϋ') rinsing or wringing, preferably wringing,

(iii') the application to the keratin fibres of a composition comprising one or more dyes, and

(^1ν') optionally a final rinsing.

Steps (i ' ) to (iv' ) may be carried out in the order indicated above, but in accordance with another particular embodiment o f the invention they may be carried out in the fo llowing order: (iii '), optionally (ϋ ' ), (ί ') and (iv' ) . The preferred leave-on times for step (i) or (ί ' ) are from 5 minutes to 24 hours, preferably from 30 minutes to 12 hours, and for step (iii ' ) they are from 10 minutes to 60 minutes, and preferably from 20 to 40 minutes.

Steps (i) and (i ' ) may be carried out at ambient temperature ( 15 to 25 °C) or under heat (from 30 to 80°C) . In operation under heat, this action may be carried out using a styling hood, a hairdryer and other conventional heating apparatus.

The invention likewise relates to a multi-compartment device comprising :

- a first compartment with a composition comprising from 50% to 90%) by weight of one or more chaotropic salts,

- a second compartment comprising at least one dye, and

- a third compartment with a composition comprising at least one oxidizing agent.

The examples which fo llow serve to illustrate the invention, but without any limitative effect and without restricting the scope of the said invention. Example 1

A 61 .5 %) by weight aqueous solution of lithium bromide is prepared, referred to hereinafter as chaotropic composition.

This chaotropic composition is then applied to pairs o f locks o f natural and permed Caucasian hair containing 90% white hairs, and is left to act for 3 hours at room temperature.

The locks o f hair are subsequently wrung and treated with co louring composition 1 , prepared from the ingredients indicated in the table below, in the fo llowing proportions, indicated in grams : Co louring

composition 1

Oxidized logwood extract containing 9% 4g

haematin and 5% haematoxylin

Benzyl alcoho l 4.8g

Ethano l 14.4g

Bentone 3.8g

Fragrance qs

Water qs ad 100g

The co louring composition is left to act for 45 minutes at 40°C, fo llowed by rinsing and shampooing with an Elseve Multi- vitamin shampoo .

Locks with an intense mahogany co loration are then obtained, more powerful than those not treated beforehand with the chaotropic composition. Furthermore, the colorations withstand 6 shampooings . Example 2

A 76.4% by weight aqueous solution o f guanidine hydrochloride is prepared.

This chaotropic composition is subsequently applied to locks of natural and permed Caucasian hair containing 90% white hairs . It is left to act overnight at room temperature.

The locks of hair are subsequently wrung and treated with co louring composition 1 , prepared from the ingredients indicated in the table below, in the fo llowing proportions, indicated in grams : Co louring

composition 1

Oxidized logwood extract containing 9% 4g

haematin and 5% haematoxylin

Benzyl alcoho l 4.8g

Ethano l 14.4g

Bentone 3.8g

Fragrance qs

Water qs ad 100g

The co louring composition is left to act for 45 minutes at 40°C, fo llowed by rinsing and shampooing with an Elseve Multivitamin shampoo .

Locks which are intensely coloured and very glossy are obtained, with more power than those not treated beforehand with the chaotropic composition.

The co lorations are mahogany on Caucasian hair. Furthermore, they withstand shampooing.

Claims

1 . Method for dyeing keratin fibres, employing :

- one or more chaotropic salts,

- one or more dyes,

in a single composition or two different compositions,

the chaotropic salt or salts being present in an amount of from 50% to 90% by weight relative to the total weight of the composition or compositions comprising it or them.

2. Method according to Claim 1 , characterized in that the chaotropic salt or salts is or are applied before the dye or dyes .

3. Method according to Claim 1 , characterized in that the chaotropic salt or salts is or are applied at the same time as the dye or dyes.

4. Method according to any one of the preceding claims, characterized in that the application of the chaotropic salt or salts is fo llowed by a step o f rinsing or wringing.

5. Method according to any one of the preceding claims, characterized in that the chaotropic salt or salts is or are chosen from chosen from guanidine salts such as guanidine hydrochloride, guanidine thiocyanate, guanidine carbonate and guanidine phosphate; aminoguanidine salts such as aminoguanidine hydrochloride and aminoguanidine bicarbonate; salts of alkali metals such as lithium, such as lithium halides and more particularly lithium bromide; alkaline earth metal salts such as magnesium salts, such as magnesium halides; and mixtures thereof.

6. Method according to any one of the preceding claims, characterized in that the chaotropic salt or salts is or are present in an amount of from 50% to 80% by weight relative to the total weight of the composition or compositions comprising it or them.

7. Method according to any one of the preceding claims, characterized in that the dyes are selected from oxidation dyes, synthetic direct dyes, natural dyes and mixtures thereof.

8. Method according to any one o f Claims 1 to characterized in that the dyes are natural and are chosen from those formula (V) :

in which:

X represents a group :

// /

H O— C or 0=C

\ \

R¹ , R², R³ , R⁴, R⁵ and R⁶, which are identical or different, represent independently o f one another a hydrogen atom, a hydroxyl group, an optionally substituted alkyl or optionally substituted alkoxy group, or an optionally substituted acyloxy group,

and also the tautomeric and/or mesomeric forms thereof, the stereoisomers thereof, the addition salts thereo f with a cosmetically acceptable acid or base, and the hydrates thereof.

9. Method according to any one o f Claims 1 to 8 , characterized in that the dyes are natural and are chosen from haematoxylin, haematein, brazilin and brazileine.

10. Method according to any one o f Claims 1 to 9, characterized in that the dyes are natural and are present in an amount of from 0.05 % to 60% by weight, preferably from 0. 1 % to 20% by weight, more preferably from 0.2% to 10% by weight, relative to the total weight of the composition comprising it or them.

1 1 . Method according to any one o f Claims 1 to 7, characterized in that the dye or dyes is or are (a) synthetic direct dye(s) and is or are present in an amount of from 0.01 % to 20% by weight, preferably from 0. 1 % to 10% by weight, more preferably from 0.2% to 5 % by weight, relative to the total weight of the composition comprising it or them.

12. Method according to any one o f Claims 1 to 7, characterized in that the dye or dyes is or are (an) oxidation dye(s) and is or are present in an amount of from 0.001 % to 10% by weight, preferably from 0.05 % to 5 % by weight, relative to the total weight of the composition comprising it or them.

13. Method according to any one of the preceding claims, characterized in that the compositions comprise water or a mixture o f water and one or more organic so lvents, more particularly chosen from ethano l, benzyl alcoho l and mixtures thereof.

14. Method according to any one of the preceding claims, characterized in that it comprises :

(i') the application o f a first composition comprising one or more chaotropic salts in an amount of from 50% to 90% by weight relative to the total weight of the first composition,

(ϋ') rinsing or wringing, preferably wringing,

(iii') the application o f a second composition comprising one or more dyes, and

(iv') optionally a final rinsing.

15. Multi-compartment device comprising :

a first compartment with a composition comprising 50% to 90% by weight of one or more chaotropic salts,

- a second compartment comprising at least one dye, and optionally a third compartment with a composition comprising at least one oxidizing agent.