PYRIDINIUM COMPOUNDS, USE THEREOF FOR TREATING HAIR AND

PROCESSES USING THEM

The present invention relates to a composition comprising one or more double pyridinium compounds and one or more chemical oxidizing agents.

The present invention also relates to a process for treating keratin materials, in particular keratin fibres, and more particularly human keratin fibres such as the hair, using said composition.

A subject of the present invention is also the use of one or more double pyridinium compounds for treating keratin materials, in particular keratin fibres, and more particularly human keratin fibres such as the hair.

Finally, the present invention relates to one or more particular double pyridinium compounds, and also to a composition comprising them.

When a person wishes to change hair colour, in particular when she wishes to obtain a lighter colour than her original colour, it is often necessary to proceed with hair lightening or bleaching. To do this, lightening or bleaching products are used. This step is optionally combined with a hair colouring step.

It is known to lighten or bleach keratin materials, in particular keratin fibres, and in particular human keratin fibres such as the hair, with lightening or bleaching compositions containing one or more chemical oxidizing agents.

Among the chemical oxidizing agents used conventionally, mention may be made of hydrogen peroxide, compounds that can produce hydrogen peroxide by hydrolysis, such as urea peroxide or persalts such as perborates, percarbonates and persulfates, hydrogen peroxide and persulfates being particularly preferred.

The role of the chemical oxidizing agent is to degrade the melanin of the hair, which, depending on the nature of the oxidizing agent and the pH conditions, leads to more or less pronounced lightening of the fibres.

The lightening or bleaching compositions are presented in anhydrous or aqueous form and in various different delivery forms: for example in the form of powders, creams, gels, foams or pastes, containing alkaline compounds such as alkaline amines or silicates, and a peroxygenated reagent such as ammonium or alkali metal persulfates, perborates or percarbonates, that are diluted at the time of use with an aqueous hydrogen peroxide composition. The lightening and bleaching compositions may also result from mixing, at the time of use, an anhydrous powder containing the peroxygenated reagent with an aqueous composition containing the alkaline compounds and another aqueous composition containing hydrogen peroxide.

Moreover, the keratin materials may also be bleached using a conventional process involving putting on said substances an aqueous composition comprising at least one oxidizing agent.

Thus, for relatively mild lightening, the oxidizing agent is generally hydrogen peroxide. When greater lightening is desired, peroxygenated salts, for instance persulfates, are usually used in the presence of hydrogen peroxide.

To make a lightening or bleaching product for keratin materials that is more effective in terms of lightening and/or speed, it is currently necessary to combine hydrogen peroxide with an alkaline agent or persulfate salts with a basic pH to deliver adequate formation of active oxygen.

However, such a combination commonly causes degradation of keratin materials, in particular keratin fibres, and may optionally lead to varying degrees of skin irritation.

Thus, there is a real need to use compounds and/or compositions which do not have the drawbacks mentioned above, i.e. which can produce, under safer conditions than for persulfates, powerful lightening of keratin materials, in particular of keratin fibres, while at the same time minimizing their degradation.

The applicant has discovered, surprisingly, that a composition comprising one or more particular double pyridinium compounds and one or more chemical oxidizing agents makes it possible to achieve the objectives set out above; in particular to produce greater lightening of keratin materials, in particular keratin fibres, while at the same time minimizing damage thereto.

A subject of the present invention is in particular a composition comprising: (a) one or more compounds of formula (I) or (II) below, the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof:

in which:

• Ro and R'o, which may be identical or different, represent, independently of each other:

- a linear or branched Ci to C ₆ alkyl radical optionally substituted with one or more identical or different radicals chosen from the hydroxyl radical, the amino radical, Ci to C ₆ mono- or dialkyl amino radicals and Ci to C ₆ alkoxy radicals,

- a hydroxyl radical;

• Ri, R ₂ , R3, R4, R5, R'i, R'2, R'3, R'4, R'5, which may be identical or different, represent, independently of each other:

- a hydrogen atom,

- a linear or branched Ci to C ₆ alkyl radical optionally substituted with one or more identical or different radicals chosen from the hydroxyl radical, the amino radical, Ci to C ₆ mono- or dialkyl amino radicals and Ci to C ₆ alkoxy radicals,

- a linear or branched Ci to C ₆ alkoxy radical,

- a halogen atom,

- an aminocarbonyl radical -C(0)-NH ₂ ;

• anion represents one or more anions intended to ensure the electroneutrality of the compound of formula (I);

• it being understood that a radical from the radicals Ri and a radical from the radicals R'i, with i representing an integer ranging from 0 to 5, together form a divalent radical L representing:

- a linear or branched, saturated or unsaturated Ci to C15 alkyl chain optionally substituted with one or more hydroxyl radicals, and/or optionally interrupted with one or more carbonyl functions and/or one or more non- adjacent atoms chosen from oxygen, nitrogen and sulfur,

- a covalent bond;

in which:

• Re et R' ₆ , which may be identical or different, represent, independently of each other, a linear or branched Ci to C ₆ alkyl radical optionally substituted with one or more identical or different radicals chosen from the hydroxyl radical, the amino radical, Ci to C ₆ mono- or dialkyl amino radicals and Ci to C ₆ alkoxy radicals,

• Ri2 and R' 12, which may be identical or different, represent, independently of each other:

- a linear or branched Ci to C ₆ alkyl radical optionally substituted with one or more identical or different radicals chosen from the hydroxyl radical, the amino radical, Ci to C ₆ mono- or dialkyl amino radicals and Ci to C ₆ alkoxy radicals,

- a hydroxyl radical;

• R7, R8, R9, Rio, R11 , R'7, R'8, R's>, R' 10, R' 11 , which may be identical or different, represent, independently of each other:

- a hydrogen atom,

- a linear or branched Ci to C ₆ alkyl radical optionally substituted with one or more identical or different radicals chosen from the hydroxyl radical, the amino radical, Ci to C ₆ mono- or dialkyl amino radicals and Ci to C ₆ alkoxy radicals,

- a linear or branched Ci to C ₆ alkoxy radical,

- a halogen atom,

- an aminocarbonyl radical -C(0)-NH ₂ ;

• anion represents one or more anions intended to ensure the electroneutrality of the compound of formula (II);

• it being understood that a radical from the radicals Rj and a radical from the radicals R'j, with j representing an integer ranging from 6 to 12, together form a divalent radical M representing:

- a linear or branched, saturated or unsaturated Ci to C15 alkyl chain optionally substituted with one or more hydroxyl radicals, and/or optionally interrupted with one or more carbonyl functions and/or one or more non- adjacent atoms chosen from oxygen, nitrogen and sulfur,

- a covalent bond; and

(b) one or more chemical oxidizing agents.

The presence of the compounds of formula (I) or (II) makes it possible in particular to improve the oxidizing power of the peroxide. In other words, the presence of these compounds of formula (I) or (II) in the composition according to the invention makes it possible to improve the activity of hydrogen peroxide without the need to increase its concentration or the need to use persulfate salts at high concentrations, which makes it possible to minimize the problems of sensitization of keratin materials.

Thus, the composition according to the invention leads to greater lightening of keratin materials without, however, needing to increase the strength of the oxidizing agent.

In other words, using double pyridinium(s) of formula (I) or (II) according to the invention makes it possible to boost the oxidizing activity of chemical oxidizing agents, in particular hydrogen peroxide, leading to improved lightening of the keratin materials compared to using the chemical oxidizing agent alone.

A subject of the present invention is also a process for lightening keratin materials, in particular keratin fibres, and in particular human keratin fibres such as the hair, consisting in applying to said keratin materials a composition as defined previously.

The present invention also relates to the use of one or more compounds of formula (I) or (II) as defined previously, and also the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof, for treating keratin materials, in particular keratin fibres, and in particular human keratin fibres such as the hair.

The present invention also relates to a double pyridinium compound of formula (III) or (IV) below, and also to the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof

in which Ro, Ri , R ₂ , R3, R4, R5, R'o, R' i , R'2, R'3, R'4, R's and L are as defined previously;

it being understood that:

- if R3 and R'3 together form a divalent radical L, then L does not represent a covalent bond,

- if Ro and R'o together form a divalent radical L, then L does not represent a hexyl chain; and

in which Re, R ₇ , Rs, R9, Rio, R11 , R12, R'e, R'7, R's, R'9, R' io, R' 11 , R' 12 and M are as defined previously;

it being understood that:

- if Re and R' ₆ together form a divalent radical M, then M does not represent an ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl or butene chain,

- if R12 and R' 12 together form a divalent radical M, then M does not represent a methyl chain.

The present invention also relates to a composition comprising one or more compounds of formula (III) or (IV), as defined previously, and also to the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof; and preferably also one or more chemical oxidizing agents. Other subjects, characteristics, aspects and advantages of the invention will emerge even more clearly on reading the description and the examples that follow.

In that which follows and unless otherwise indicated, the limits of a range of values are included within this range, in particular in the expressions "of between" and "ranging from ... to

Moreover, the expressions "at least one" and "at least" used in this description are equivalent to the expressions "one or more" and "greater than or equal" respectively. Composition

Compounds of formula (I) or (II)

The composition according to the present invention comprises one or more compounds (a) chosen from the compounds of formula (I) as defined previously, the compounds of formula (II) as defined previously, the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof.

In formula (I), L advantageously represents a linear and saturated Ci to Cs alkyl chain optionally substituted with a hydroxyl radical, and/or optionally interrupted with one or more carbonyl functions, and/or one or more non-adjacent atoms chosen from oxygen and nitrogen.

In formula (II), M preferably represents a linear or branched Ci to Cs alkylene chain optionally substituted with one or more hydroxyl radicals, and/or optionally interrupted with one or more non-adjacent atoms chosen from oxygen and nitrogen.

In formula (II), M advantageously represents a linear and saturated Ci to Cs alkyl chain optionally substituted with a hydroxyl radical, and/or optionally interrupted with an oxygen atom, preferably M represents a pentyl, oxydiethyl or hydroxypropyl chain.

Preferably, in formula (I) or (II), Ro and R12 are respectively identical to or different from R'o and R' 12, and represent, independently of each other, a linear or branched Ci to C ₄ alkyl radical or a hydroxyl radical. In other words, Ro is identical to or different from R'o, and R12 is identical to or different from R' 12.

More preferentially, in the compounds of formula (II), R7, Rs, Rio, R11, R'7, R'8, R' 10 and R'n are identical and each represent a hydrogen atom. Even better still, R ₇ , R8, Rio, R11, R'7, R'8, R'10 and R' n are identical and each represent a hydrogen atom and R12 and R'12, which may be identical or different, represent, independently of each other, a linear or branched Ci to C ₄ alkyl radical or a hydroxyl radical.

According to one preferred embodiment, in formula (I) or (II), Ri and Rj are respectively identical to R'i and R'j. In other words, Ro is identical to R'o, Ri is identical to R'i, R2 is identical to R'2, R3 is identical to R'3, R4 is identical to R' ₄ , R5 is identical to R'5, Re is identical to R' ₆ , R7 is identical to R'7, Rs is identical to R's, R9 is identical to R'9, Rio is identical to R'10, R11 is identical to R' n , and R12 is identical to R'12.

According to a first preferred embodiment, in formula (I), Ro and R'o are identical and each denote a linear Ci to C ₆ , preferentially Ci and C ₄ , and even better still Ci, alkyl radical.

According to a second preferred embodiment, in formula (I), Ro and R'o are identical and each denote a hydroxyl radical.

According to a third preferred embodiment, in formula (II), R12 and R'12 are identical and each denote a linear Ci to C ₆ , preferentially Ci and C ₄ , and even better still Ci, alkyl radical.

Anion denotes a cosmetically acceptable anion or anion mixture intended to ensure the electroneutrality of the compounds of formula (I) or (II).

Anion is advantageously chosen from halides, such as chloride or bromide; nitrates; sulfonates, in particular Ci-C ₆ alkylsulfonates (Alk-S(0)20 ^~ ) such as methyl sulfonate, mesylate and ethyl sulfonate; arylsulfonates (Ar-S(0)20 ^~ ) such as benzenesulfonate, toluenesulfonate or tosylate; citrate; succinate; tartrate; lactate; alkyl sulfates (Alk-O-S(O)O ) such as methyl sulfate or ethyl sulfate; arylsulfates (Ar-O-S(O)O ) such as benzenesulfate or toluenesulfate; alkoxysulfates (Alk-O- S(0)20 ^" ) such as methoxy sulfate or ethoxysulfate; aryloxy sulfates (Ar-0-S(0)20 ^~ ); phosphates such as 0=Ρ(ΟΗ) ₂ -0 ^" , 0=Ρ(0>ΟΗ 0=P(0 ) ₃ , HO-[P(0)(0 )] _w -P(0)(0- )i with w being an integer between 1 and 15; acetate; triflate; borates such as tetrafluoroborate; disulfates such as or S0 ₄ ^2~ ; monosulfate HS0 ₄ ^" and mixtures thereof.

More preferentially, Anion is chosen from halides, and even better still from bromide or chloride. Preferably, the compound(s) (a) are chosen from the following compounds, and also the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof:

3,3'-[ethane-l,2- diylbis(iminomethanediyl)]bis[ 1 - (carboxymethyl)pyridinium] dichloride

1 , 1 '-pentane- 1 ,2-diylbis(4- acetylpyridinium) dibromide

(2)

1 , 1 '-(oxydiethane-2, 1 -diyl)bis(4- acetylpyridinium) dibromide

(3)

1 , 1 '-(2-hydroxypropane- 1,3- diyl)bis(4-acetylpyridinium) dibromide

4,4'-[ethane-l,2- diylbis(iminomethanediyl)]bis[ 1 - (2-oxopropyl)pyridinium] dichloride

2,2'-[ethane-l,2- diylbis(iminomethanediyl)]bis[ 1 - (2-oxopropyl)pyridinium] dichloride

The addition salts of the compounds of formula (I) or (II) according to the present invention are in particular chosen from the addition salts thereof with an acid, such as the hydrochlorides, hydrobromides, sulfates, citrates, succinates, tartrates, lactates, tosylates, benzenesulfonates, phosphates and acetates, and the addition salts thereof with a base such as sodium hydroxide, potassium hydroxide, ammonia, amines or alkanolamines.

Moreover, the solvates of the compounds of formula (I) or (II) more particularly represent the hydrates of said compounds and/or the combination of said compounds with a linear or branched Ci to C ₄ alcohol such as methanol, ethanol, isopropanol or n-propanol. Preferably, the solvates are hydrates.

The amount of the compound(s) of formula (I) or (II) present in the composition according to the invention preferably ranges from 0.01% to 10% by weight and more preferentially from 0.5% to 6% by weight relative to the total weight of the composition.

Chemical oxidizing agents

The composition according to the present invention comprises one or more chemical oxidizing agents.

The term "chemical oxidizing agent" is intended to mean an oxidizing agent other than atmospheric oxygen.

More particularly, the chemical oxidizing agent(s) are chosen from hydrogen peroxide, hydrogen peroxide-generating systems, urea peroxide, alkali metal bromates or ferricyanides, peroxygenated salts, for instance persulfates, perborates, peracids and precursors thereof and percarbonates of alkali metals or alkaline-earth metals, and mixtures thereof.

Preferably, the chemical oxidizing agent(s) are chosen from hydrogen peroxide or hydrogen peroxide-generating systems.

According to one preferred embodiment, the hydrogen peroxide-generating system(s) are chosen from urea peroxide, polymeric complexes that can release hydrogen peroxide, chosen from polyvinylpyrrolidone/IHbC ; oxidases; perborates; and percarbonates.

Preferably, the chemical oxidizing agent is hydrogen peroxide, and more preferentially aqueous hydrogen peroxide solution.

The chemical oxidizing agent(s) are advantageously introduced in the form of an aqueous solution of which the content of chemical oxidizing agents is preferably between 20 volumes and 200 volumes when the oxidizing agent is aqueous hydrogen peroxide.

The final content of oxidizing agent in the composition is, for its part, preferentially between 5 volumes and 40 volumes.

Fatty substances

The composition according to the present invention may optionally also comprise one or more fatty substances.

The term "fatty substance" is intended to mean an organic compound that is insoluble in water at ordinary temperature (25°C) and at atmospheric pressure (760 mmHg) (solubility of less than 5%, preferably less than 1% and even more preferentially less than 0.1%). They bear in their structure at least one hydrocarbon- based chain including at least 6 carbon atoms or a sequence of at least two siloxane groups. In addition, the fatty substances are generally soluble in organic solvents under the same temperature and pressure conditions, for instance chloroform, dichloromethane, carbon tetrachloride, ethanol, benzene, toluene, tetrahydrofuran (THF), liquid petroleum jelly or decamethylcyclopentasiloxane.

Preferably, the fatty substances of the invention do not contain any salified or unsalified carboxylic acid groups (-C(O)OH or -C(O)O-). Particularly, the fatty substances of the invention are neither polyoxyalkylenated nor polyglycerolated.

Preferably, the fatty substances that may be used in the composition according to the invention are non-silicone oils.

The term "oil" is intended to mean a fatty substance that is liquid at ambient temperature (25°C) and at atmospheric pressure (760 mmHg).

The term "non-silicone oil" is intended to mean an oil not containing any silicon atoms (Si) and the term "silicone oil" is intended to mean an oil containing at least one silicon atom.

More particularly, the fatty substance(s) are chosen from C ₆ to C ₁₆ hydrocarbons, hydrocarbons containing more than 16 carbon atoms, non-silicone oils of animal origin, plant oils of triglyceride type, synthetic triglycerides, fluoro oils, fatty alcohols and fatty acids, esters of fatty acids and/or of fatty alcohols other than triglycerides, and plant waxes, non-silicone waxes and silicones, and mixtures thereof.

It is recalled that, for the purposes of the invention, the fatty alcohols, fatty esters and fatty acids more particularly contain one or more linear or branched, saturated or unsaturated hydrocarbon-based groups comprising 6 to 30 carbon atoms, which are optionally substituted, in particular, with one or more (in particular 1 to 4) hydroxyl groups. If they are unsaturated, these compounds may comprise one to three conjugated or unconjugated carbon-carbon double bonds.

As regards the C ₆ to C ₁₆ hydrocarbons, they are linear, branched or optionally cyclic, and are preferably alkanes. Examples that may be mentioned include hexane, dodecane and isoparaffins such as isohexadecane and isodecane.

A hydrocarbon-based oil of animal origin that may be mentioned is perhydrosqualene.

The triglyceride oils of plant or synthetic origin are preferably chosen from liquid fatty acid triglycerides containing from 6 to 30 carbon atoms, for instance heptanoic or octanoic acid triglycerides, or alternatively, for example, sunflower seed oil, corn oil, soy bean oil, pumpkin oil, grapeseed oil, sesame seed oil, hazelnut oil, apricot oil, macadamia oil, arara oil, castor oil, avocado oil, tea seed oil, passion seed oil, meadowfoam seed oil, caprylic/capric acid triglycerides, for instance those sold by the company Stearineries Dubois or those sold under the names Miglyol ^® 810, 812 and 818 by the company Dynamit Nobel, jojoba oil and shea butter oil.

The linear or branched hydrocarbons of mineral or synthetic origin, containing more than 16 carbon atoms, are preferably chosen from liquid paraffins, petroleum jelly, liquid petroleum jelly, polydecenes and hydrogenated polyisobutene such as Parleam ^® .

The fluoro oils may be chosen from perfluoromethylcyclopentane and perfluoro-l,3-dimethylcyclo hexane, sold under the names Flutec® PCI and Flutec® PC3 by the company BNFL Fluorochemicals; perfluoro-l,2-dimethylcyclo butane; perfluoroalkanes such as dodecafluoropentane and tetradecafluorohexane, sold under the names PF 5050® and PF 5060® by the company 3M, or alternatively bromoperfluorooctyl sold under the name Foralkyl® by the company Atochem; nonafluoromethoxybutane and nonafluoroethoxyisobutane; perfluoromorpholine derivatives such as 4-trifluoromethyl perfluoromorpholine sold under the name PF 5052® by the company 3M.

The fatty alcohols that may be used in the composition according to the invention are saturated or unsaturated, and linear or branched, and include from 6 to 30 carbon atoms and more particularly from 8 to 18 carbon atoms. Examples that may be mentioned include cetyl alcohol, stearyl alcohol and the mixture thereof (cetylstearyl alcohol), octyldodecanol, 2-butyloctanol, 2-hexyldecanol, 2- undecyl-pentadecanol, oleyl alcohol and linoleyl alcohol.

The wax(es) that may be used in the composition according to the invention are chosen in particular from carnauba wax, candelilla wax, esparto grass wax, paraffin wax, ozokerite, plant waxes, for instance olive wax, rice wax, hydrogenated jojoba wax or the absolute waxes of flowers such as the essential wax of blackcurrant blossom sold by the company Bertin (France), animal waxes, for instance beeswaxes, or modified beeswaxes (cerabellina); other waxes or waxy starting materials that may be used according to the invention are in particular marine waxes such as the product sold by the company Sophim under the reference M82, and polyethylene waxes or polyolefm waxes in general.

As regards the fatty acid and/or fatty alcohol esters, which are advantageously different from the triglycerides mentioned above, mention may be made in particular of esters of saturated or unsaturated, linear or branched Ci to C ₂₆ aliphatic mono- or polyacids and of saturated or unsaturated, linear or branched Ci to C ₂ 6 aliphatic mono- or polyalcohols, the total carbon number of the esters more particularly being greater than or equal to 10.

Among the monoesters, mention may be made of dihydroabietyl behenate; octyldodecyl behenate; isocetyl behenate; cetyl lactate; C ₁₂ -C ₁₅ alkyl lactate; isostearyl lactate; lauryl lactate; linoleyl lactate; oleyl lactate; (iso)stearyl octanoate; isocetyl octanoate; octyl octanoate; cetyl octanoate; decyl oleate; isocetyl isostearate; isocetyl laurate; isocetyl stearate; isodecyl octanoate; isodecyl oleate; isononyl isononanoate; isostearyl palmitate; methyl acetyl ricinoleate; myristyl stearate; octyl isononanoate; 2-ethylhexyl isononanoate; octyl palmitate; octyl pelargonate; octyl stearate; octyldodecyl erucate; oleyl erucate; ethyl and isopropyl palmitates, 2- ethylhexyl palmitate, 2-octyldecyl palmitate, alkyl myristates such as isopropyl, butyl, cetyl, 2-octyldodecyl, myristyl or stearyl myristate, hexyl stearate, butyl stearate, isobutyl stearate; dioctyl malate, hexyl laurate, 2-hexyldecyl laurate.

Still within the context of this variant, esters of C ₄ to C ₂₂ dicarboxylic or tricarboxylic acids and of Ci to C ₂₂ alcohols and esters of mono-, di- or tricarboxylic acids and of C ₂ to C ₂₆ di-, tri-, tetra- or pentahydroxy alcohols may also be used.

Mention may in particular be made of: diethyl sebacate; diisopropyl sebacate; diisopropyl adipate; di(n-propyl) adipate; dioctyl adipate; diisostearyl adipate; dioctyl maleate; glyceryl undecylenate; octyldodecyl stearoyl stearate; pentaerythrityl monoricinoleate; pentaerythrityl tetraisononanoate; pentaerythrityl tetrapelargonate; pentaerythrityl tetraisostearate; pentaerythrityl tetraoctanoate; propylene glycol dicaprylate; propylene glycol dicaprate; tridecyl erucate; triisopropyl citrate; triisostearyl citrate; glyceryl trilactate; glyceryl trioctanoate; trioctyldodecyl citrate; trioleyl citrate; propylene glycol dioctanoate; neopentyl glycol diheptanoate; diethylene glycol diisononanoate; and polyethylene glycol distearates.

Among the esters mentioned above, it is preferred to use ethyl, isopropyl, myristyl, cetyl or stearyl palmitate, 2-ethylhexyl palmitate, 2-octyldecyl palmitate, alkyl myristates such as isopropyl, butyl, cetyl or 2-octyldodecyl myristate, hexyl stearate, butyl stearate, isobutyl stearate; dioctyl malate, hexyl laurate, 2-hexyldecyl laurate, isononyl isononanoate or cetyl octanoate.

The composition may also comprise, as fatty ester, sugar esters and diesters of C ₆ to C30 and preferably C ₁₂ to C22 fatty acids. It is recalled that the term "sugar" is intended to mean oxygen-bearing hydrocarbon-based compounds bearing several alcohol functions, with or without aldehyde or ketone functions, and which comprise at least 4 carbon atoms. These sugars may be monosaccharides, oligosaccharides or polysaccharides.

Examples of suitable sugars that may be mentioned include sucrose (or saccharose), glucose, galactose, ribose, fucose, maltose, fructose, mannose, arabinose, xylose and lactose, and derivatives thereof, in particular alkyl derivatives, such as methyl derivatives, for instance methylglucose.

The sugar esters of fatty acids may be chosen in particular from the group comprising the esters or mixtures of esters of sugars described previously and of linear or branched, saturated or unsaturated C ₆ to C30 and preferably C ₁₂ to C22 fatty acids. If they are unsaturated, these compounds may comprise one to three conjugated or unconjugated carbon-carbon double bonds.

The esters according to this variant may also be chosen from mono-, di-, tri- and tetraesters, polyesters, and mixtures thereof.

These esters may be, for example, oleates, laurates, palmitates, myristates, behenates, cocoates, stearates, linoleates, linolenates, caprates and arachidonates, or mixtures thereof such as, in particular, oleopalmitate, oleostearate and palmitostearate mixed esters. More particularly, use is made of monoesters and diesters and in particular sucrose, glucose or methylglucose monooleate or dioleate, stearate, behenate, oleopalmitate, linoleate, linolenate or oleostearate.

Mention may be made, by way of example, of the product sold under the name Glucate ^® DO by the company Amerchol, which is a methylglucose dioleate.

Examples of esters or mixtures of esters of sugar and of fatty acid that may also be mentioned include:

- the products sold under the names F160, F140, F110, F90, F70 and SL40 by the company Crodesta, respectively denoting sucrose palmitostearates formed from 73% monoester and 27% diester and triester, from 61% monoester and 39% diester, triester and tetraester, from 52% monoester and 48% diester, triester and tetraester, from 45% monoester and 55% diester, triester and tetraester, from 39% monoester and 61 > diester, triester and tetraester, and sucrose monolaurate;

- the products sold under the name Ryoto Sugar Esters, for example referenced B370 and corresponding to sucrose behenate formed of 20%> monoester and 80%) diester, triester and polyester;

- the sucrose mono-dipalmitate/stearate sold by the company Goldschmidt under the name Tegosoft ^® PSE.

The silicones that may be used in accordance with the invention may be in the form of oils, waxes, resins or gums.

Preferably, the silicone is chosen from polydialkylsiloxanes, in particular polydimethylsiloxanes (PDMSs), and organomodified polysiloxanes including at least one functional group chosen from amino groups, aryl groups and alkoxy groups.

Organopolysiloxanes are defined in greater detail in Walter Noll's Chemistry and Technology of Silicones (1968), Academic Press. They may be volatile or non-volatile.

When they are volatile, the silicones are more particularly chosen from those with a boiling point of between 60°C and 260°C, and even more particularly from:

(i) cyclic polydialkylsiloxanes comprising from 3 to 7 and preferably from 4 to 5 silicon atoms. These are, for example, octamethylcyclotetrasiloxane sold in particular under the name Volatile Silicone ^® 7207 by Union Carbide or Silbione ^® 70045 V2 by Rhodia, decamethylcyclopentasiloxane sold under the name Volatile Silicone ^® 7158 by Union Carbide, and Silbione ^® 70045 V5 by Rhodia, and mixtures thereof. Mention may also be made of cyclocopolymers of the dimethylsiloxane/methylalkylsiloxane type, such as Volatile Silicone® FZ 3109 sold by the company Union Carbide, having formula:

D" - D' - D" - D' ^■

CH, CH, with D" Si - O— with D' Si

I CH, c _D

Mention may also be made of mixtures of cyclic polydialkylsiloxanes with organosilicon compounds, such as the mixture of octamethylcyclotetrasiloxane and tetra(trimethylsilyl)pentaerythritol (50/50) and the mixture of octamethylcyclotetrasiloxane and oxy-l,l '-bis(2,2,2',2',3,3'- hexatrimethylsilyloxy)neopentane;

(ii) linear volatile polydialkylsiloxanes containing 2 to 9 silicon atoms and having a viscosity of less than or equal to 5x10 ^"6 m ² /s at 25°C. An example is decamethyltetrasiloxane sold in particular under the name SH 200 by the company Toray Silicone. Silicones belonging to this category are also described in the article published in Cosmetics and Toiletries, Vol. 91, Jan. 76, pp. 27-32, Todd & Byers, "Volatile Silicone Fluids for Cosmetics".

Non-volatile polydialkylsiloxanes, polydialkylsiloxane gums and resins, polyorganosiloxanes modified with the above organofunctional groups, and mixtures thereof, are preferably used.

These silicones are more particularly chosen from polydialkylsiloxanes, among which mention may be made mainly of polydimethylsiloxanes bearing trimethylsilyl end groups. The viscosity of the silicones is measured at 25 °C according to ASTM Standard 445 Appendix C.

Among these polydialkylsiloxanes, mention may be made, in a nonlimiting manner, of the following commercial products:

- the Silbione ^® oils of the 47 and 70 047 series or the Mirasil ^® oils sold by Rhodia, for instance the oil 70 047 V 500 000;

- the oils of the Mirasil ^® series sold by the company Rhodia; - the oils of the 200 series from the company Dow Corning, such as DC200 with a viscosity of 60,000 mm ² /s;

- the Viscasil® oils from General Electric and certain oils of the SF series (SF 96, SF 18) from General Electric.

Mention may also be made of polydimethylsiloxanes having dimethylsilanol end groups known as dimethiconol (CTFA), such as the oils in the 48 series from Rhodia.

In this category of polydialkylsiloxanes, mention may also be made of the products sold under the names Abil Wax® 9800 and 9801 by the company Goldschmidt, which are poly(Ci-C2o)dialkylsiloxanes.

The silicone gums that may be used in accordance with the invention are in particular polydialkylsiloxanes and preferably polydimethylsiloxanes with high number-average molecular weights of between 200 000 and 1 000 000, used alone or as a mixture in a solvent. This solvent may be chosen from volatile silicones, polydimethylsiloxane (PDMS) oils, polyphenylmethylsiloxane (PPMS) oils, isoparaffins, polyisobutylenes, methylene chloride, pentane, dodecane and tridecane, or mixtures thereof.

Products that may be used more particularly in accordance with the invention are mixtures such as:

- the mixtures formed from a hydroxy-terminated polydimethylsiloxane or dimethiconol (CTFA) chain, and from a cyclic polydimethylsiloxane, also known as cyclomethicone (CTFA), such as the product Q2 1401 sold by the company Dow Corning;

- mixtures of a polydimethylsiloxane gum and of a cyclic silicone, such as the product SF 1214 Silicone Fluid from the company General Electric; this product is an SF 30 gum corresponding to a dimethicone, having a number-average molecular weight of 500 000, dissolved in the oil SF 1202 Silicone Fluid corresponding to decamethylcyclopentasiloxane;

- mixtures of two PDMSs with different viscosities, and more particularly of a PDMS gum and of a PDMS oil, such as the product SF 1236 from the company

General Electric. The product SF 1236 is the mixture of a gum SE 30 defined above, with a viscosity of 20 m ² /s and of an oil SF 96 with a viscosity of 5x 10 ^"6 m ² /s. This product preferably includes 15% of gum SE 30 and 85% of an oil SF 96. The organopolysiloxane resins that may be used in accordance with the invention are crosslinked siloxane systems containing the following units:

R2S1O2/2, R3S1O1/2, RS1O3/2 and S1O4/2,

in which R represents an alkyl containing 1 to 16 carbon atoms. Among these products, the ones that are particularly preferred are those in which R denotes a C1 -C4 lower alkyl group, more particularly methyl.

Among these resins, mention may be made of the product sold under the name Dow Corning 593 or those sold under the names Silicone Fluid SS 4230 and SS 4267 by the company General Electric, which are silicones of dimethyl/trimethylsiloxane structure.

Mention may also be made of the trimethyl siloxysilicate-type resins sold in particular under the names X22-4914, X21-5034 and X21-5037 by the company Shin-Etsu.

The organomodified silicones that may be used in accordance with the invention are silicones as defined above and comprising in their structure one or more organo functional groups attached via a hydrocarbon-based group.

The organomodified silicones may be polydiarylsiloxanes, in particular polydiphenylsiloxanes, and polyalkylarylsiloxanes functionalized with the organofunctional groups mentioned previously.

The polyalkylarylsiloxanes are particularly chosen from linear and/or branched polydimethyl/methylphenylsiloxanes and polydimethyl/diphenylsiloxanes with a viscosity ranging from 1 x 10 ^"5 to 5 ^X 10 ^"2 m ² /s at 25°C.

Among these polyalkylarylsiloxanes, examples that may be mentioned include the products sold under the following names:

- the Silbione ^® oils of the 70 641 series from Rhodia;

- the oils of the Rhodorsil ^® 70 633 and 763 series from Rhodia;

- the oil Dow Corning 556 Cosmetic Grade Fluid from Dow Corning;

- the silicones of the PK series from Bayer, such as the product PK20;

- the silicones of the PN and PH series from Bayer, such as the products PNlOOO and PHlOOO;

- certain oils of the SF series from General Electric, such as SF 1023, SF 1154, SF 1250 and SF 1265.

Among the organomodified silicones, mention may also be made of polyorganosiloxanes comprising: - substituted or unsubstituted amino groups, such as the products sold under the names GP 4 Silicone Fluid and GP 7100 by the company Genesee or the products sold under the names Q2 8220 and Dow Corning 929 or 939 by the company Dow Corning. The substituted amino groups are, in particular, Ci to C ₄ aminoalkyl groups;

- alkoxylated groups, such as the product sold under the name Silicone Copolymer F-755 by SWS Silicones and Abil Wax ^® 2428, 2434 and 2440 by the company Goldschmidt.

Preferably, the fatty substances that may be used in the composition according to the invention are non-silicone fatty substances.

Preferably, the fatty substance(s) are chosen from hydrocarbons containing more than 16 carbon atoms, fatty alcohols and mixtures thereof, and more preferentially from liquid petroleum jelly, 2-octyldodecanol and cetylstearyl alcohol, and mixtures thereof.

The content of fatty substance(s), when it (they) is (are) present in the composition of the invention, is preferably greater than or equal to 10% by weight, more preferentially greater than or equal to 15% by weight, even better still greater than or equal to 20% by weight, and even more advantageously greater than or equal to 25% by weight, relative to the total weight of the composition.

Surfactants

The composition according to the present invention may optionally also comprise one or more surfactants.

The surfactant(s) that may be used in the composition according to the invention may be chosen from non-ionic surfactants, cationic surfactants, anionic surfactants, amphoteric or zwitterionic surfactants, and mixtures thereof.

The composition according to the present invention may comprise one or more non- ionic surfactants.

The non- ionic surfactants that may be used are described, for example, in the Handbook of Surfactants by M.R. Porter, published by Blackie & Son (Glasgow and London), 1991 , pp. 1 16-178.

Examples of non-ionic surfactants that may be mentioned include the following non- ionic surfactants:

- oxyalkylenated (Cs-C2 ₄ )alkylphenols; - saturated or unsaturated, linear or branched, oxyalkylenated or glycerolated C8-C40 alcohols, comprising one or two fatty chains;

- saturated or unsaturated, linear or branched, oxyalkylenated C8-C30 fatty acid amides;

- esters of saturated or unsaturated, linear or branched, C8-C30 acids and of polyethylene glycols;

- preferably oxyethylenated esters of saturated or unsaturated, linear or branched, C ₈ - C30 acids and of sorbitol;

- esters of fatty acids and of sucrose;

- (C8-C3o)alkyl(poly)glucosides, (C8-C3o)alkenyl(poly)glucosides, which are optionally oxyalkylenated (0 to 10 oxyalkylene units) and comprising from 1 to 15 glucose units, (C8-C3o)alkyl (poly)glucoside esters;

- saturated or unsaturated oxyethylenated plant oils;

- condensates of ethylene oxide and/or of propylene oxide;

- N-(C8-C3o)alkylglucamine and N-(C8-C3o)acylmethylglucamine derivatives;

- aldobionamides;

- amine oxides;

- oxyethylenated and/or oxypropylenated silicones;

- and mixtures thereof.

The oxyalkylene units are more particularly oxyethylene or oxypropylene units, or their combination, preferably oxyethylene units.

The number of moles of ethylene oxide and/or propylene oxide preferably ranges from 1 to 250, more particularly from 2 to 100 and better still from 2 to 50; the number of moles of glycerol ranges in particular from 1 to 50 and better still from 1 to 10.

Advantageously, the non-ionic surfactants according to the invention do not comprise any oxypropylene units.

By way of example of glycerolated non- ionic surfactants, use may preferably be made of monoglycerolated or polyglycerolated C8-C40 alcohols comprising from 1 to 50 mol of glycerol, preferably from 1 to 10 mol of glycerol.

As examples of compounds of this type, mention may be made of lauryl alcohol containing 4 mol of glycerol (INCI name: Polyglyceryl-4 Lauryl Ether), lauryl alcohol comprising 1.5 mol of glycerol, oleyl alcohol comprising 4 mol of glycerol (INCI name: Polyglyceryl-4 Oleyl Ether), oleyl alcohol comprising 2 mol of glycerol (INCI name: Polyglyceryl-2 Oleyl Ether), cetearyl alcohol containing 2 mol of glycerol, cetearyl alcohol containing 6 mol of glycerol, oleyl/cetyl alcohol containing 6 mol of glycerol, and octadecanol containing 6 mol of glycerol.

Among the glycerolated alcohols, it is more particularly preferred to use the Cs/Cio alcohol containing 1 mol of glycerol, the C ₁₀ /C ₁₂ alcohol containing 1 mol of glycerol and the C ₁₂ alcohol containing 1.5 mol of glycerol.

The non-ionic surfactant(s) that may be used in the dye composition according to the invention are preferentially chosen from:

- oxyethylenated C8-C40 alcohols comprising from 1 to 100 mol of ethylene oxide, preferably from 2 to 50 and more particularly from 2 to 40 mol of ethylene oxide and comprising one or two fatty chains;

- saturated or unsaturated oxyethylenated plant oils comprising from 1 to 100 and preferably from 2 to 50 mol of ethylene oxide;

- (C8-C3o)alkyl(poly)glucosides, which are optionally oxyalkylenated (0 to 10 OE) and comprising 1 to 15 glucose units;

- monoglycerolated or polyglycerolated C8-C40 alcohols, comprising from 1 to 50 mol of glycerol and preferably from 1 to 10 mol of glycerol;

- saturated or unsaturated, linear or branched, oxyalkylenated C8-C30 fatty acid amides;

- esters of saturated or unsaturated, linear or branched, C8-C30 acids and of polyethylene glycols;

- and mixtures thereof.

The composition according to the present invention may comprise one or more cationic surfactants.

The term "cationic surfactant" is intended to mean a surfactant that is positively charged when it is contained in the compositions according to the invention. This surfactant may bear one or more positive permanent charges or may contain one or more cationizable functions in the compositions according to the invention.

The cationic surfactant(s) are preferably chosen from primary, secondary or tertiary fatty amines, which are optionally polyoxyalkylenated, or salts thereof, and quaternary ammonium salts, and mixtures thereof.

The fatty amines generally comprise at least one Cs to C30 hydrocarbon- based chain. Mention may in particular be made, as quaternary ammonium salts, for example, of:

- those corresponding to the general formula (V) below:

(V)

in which the groups R ₂ 8 to R31 , which may be identical or different, represent a linear or branched aliphatic group containing from 1 to 30 carbon atoms, or an aromatic group such as aryl or alkylaryl, at least one of the groups R ₂ 8 to R31 denoting a group containing from 8 to 30 carbon atoms, preferably from 12 to 24 carbon atoms. The aliphatic groups may comprise heteroatoms such as, in particular, oxygen, nitrogen, sulfur and halogens. The aliphatic groups are chosen, for example, from C1-C30 alkyl, C1-C30 alkoxy, polyoxy(C ₂ -C6)alkylene, C1-C30 alkylamide, (Ci2-C ₂ 2)alkylamido(C ₂ - C ₆ )alkyl, (Ci2-C ₂₂ )alkyl acetate, and C1-C30 hydroxyalkyl groups, X ^" is an anion chosen from the group of halides, phosphates, acetates, lactates, (Ci-C4)alkyl sulfates, and (Ci-C4)alkyl- or (Ci-C4)alkylarylsulfo nates.

Among the quaternary ammonium salts of formula (V), those that are preferred are, on the one hand, tetraalkylammonium salts, for instance dialkyldimethylammonium or alkyltrimethylammonium salts in which the alkyl group contains approximately from 12 to 22 carbon atoms, in particular behenyltrimethylammonium, distearyldimethylammonium, cetyltrimethylammonium or benzyldimethylstearylammonium salts, or, on the other hand, the palmitylamidopropyltrimethylammonium salts, the stearamidopropyltrimethylammonium salts, the stearamidopropyldimethylcetearylammonium salts, or the stearamidopropyldimethyl(myristyl acetate)ammonium salts sold under the name Ceraphyl ^® 70 by the company Van Dyk. It is preferable in particular to use the chloride salts of these compounds.

- quaternary ammonium salts of imidazoline, for instance those of formula (VI) below:

(VI) in which:

R32 represents an alkenyl or alkyl group comprising from 8 to 30 carbon atoms, for example derived from tallow fatty acids,

R33 represents a hydrogen atom, a Ci to C ₄ alkyl group or an alkenyl or alkyl group comprising from 8 to 30 carbon atoms,

R34 represents a Ci to C ₄ alkyl group,

R35 represents a hydrogen atom or a Ci to C ₄ alkyl group,

- X ^" is an anion chosen from the group of halides, phosphates, acetates, lactates, alkyl sulfates, alkyl- or alkylaryl-sulfonates in which the alkyl and aryl groups preferably comprise, respectively, from 1 to 20 carbon atoms and from 6 to 30 carbon atoms.

Preferably, R32 and R33 denote a mixture of alkenyl or alkyl groups comprising from 12 to 21 carbon atoms, for example derived from tallow fatty acids, R34 denotes a methyl group and R35 denotes a hydrogen atom. Such a product is sold, for example, under the name Rewoquat ^® W 75 by Rewo.

- diquaternary or triquaternary ammonium salts, in particular of formula

(VII):

(VII) in which: R36 denotes an alkyl radical including approximately from 16 to 30 carbon atoms, which is optionally hydroxylated and/or interrupted with one or more oxygen atoms,

R37 is chosen from hydrogen or an alkyl radical comprising from 1 to 4 carbon atoms or a group (R36a)(R37a)(R38a)N-(CH ₂ )3,

R36a, R37a, R38a, R38, R39, R40 and R41 , which may be identical or different, are chosen from hydrogen and an alkyl radical comprising from 1 to 4 carbon atoms, and

X ^" is an anion chosen from the group of halides, acetates, phosphates, nitrates and methyl sulfates.

Such compounds are, for example, Finquat CT-P available from the company Finetex (Quaternium 89), and Finquat CT, available from the company Finetex (Quaternium 75).

- quaternary ammonium salts containing at least one ester function, such as those of formula (VIII) below:

which:

R4 ₂ is chosen from Ci to C ₆ alkyl groups and Ci to C ₆ hydroxyalkyl dihydroxyalkyl groups;

R43 is chosen from:

O

R,

- the group ⁴⁶

- groups R47, which are saturated or unsaturated and linear or branched Ci to C ₂₂ hydrocarbon-based groups,

- a hydrogen atom,

R45 is chosen from:

O

R,

- the group 8 - groups R49, which are saturated or unsaturated and linear or branched Ci to C ₆ hydrocarbon-based groups,

- a hydrogen atom,

R44, R46 and R48, which may be identical or different, are chosen from linear or branched, saturated or unsaturated C7 to C21 hydrocarbon- based groups,

r, s and t, which may be identical or different, are integers having values from 2 to 6;

y is an integer having a value from 1 to 10;

- x and z, which may be identical or different, are integers having a value from 0 to 10;

X ^" is a simple or complex and organic or inorganic anion;

with the proviso that the sum x + y + z is from 1 to 15, that when x is 0 then R43 denotes R47, and that when z is 0 then R45 denotes R49.

The alkyl groups R42 may be linear or branched, and more particularly linear.

Preferably, R42 denotes a methyl, ethyl, hydroxyethyl or dihydroxypropyl group, and more particularly a methyl or ethyl group.

Advantageously, the sum x + y + z is from 1 to 10.

When R43 is a hydrocarbon-based group R47, it may be long and contain from 12 to 22 carbon atoms, or may be short and contain from 1 to 3 carbon atoms.

When R45 is a hydrocarbon-based group R49, it preferably contains 1 to 3 carbon atoms.

Advantageously, R44, R46 and R48, which may be identical or different, are chosen from linear or branched, saturated or unsaturated Cn to C21 hydrocarbon- based groups, and more particularly from linear or branched, saturated or unsaturated Cn to C21 alkyl and alkenyl groups.

Preferably, x and z, which may be identical or different, have the value 0 or

1.

Advantageously, y is equal to 1.

Preferably, r, s and t, which may be identical or different, have the value 2 or 3 and more particularly still are equal to 2.

The anion X ^" is preferably a halide (chloride, bromide or iodide) or an alkyl sulfate, more particularly methyl sulfate. However, use may be made of methanesulfonate, phosphate, nitrate, tosylate, an anion derived from an organic acid, such as acetate or lactate, or any other anion which is compatible with the ammonium having an ester function.

The anion X ^" is more particularly still chloride or methyl sulfate.

Use is made more particularly in the dye composition according to the invention of the ammonium salts of formula (VIII) in which:

R42 denotes a methyl or ethyl group,

x and y are equal to 1 ;

z is equal to 0 or 1 ;

r, s and t are equal to 2;

R43 is chosen from:

O

- the group ^ ⁴⁶ ^

- methyl, ethyl or C14 to C22 hydrocarbon-based groups,

- a hydrogen atom;

R45 is chosen from:

O

- the group ^ ⁴⁸ ^

- a hydrogen atom;

R44, R46 and R48, which may be identical or different, are chosen from saturated or unsaturated and linear or branched C13 to C ₁₇ hydrocarbon-based groups and preferably from saturated or unsaturated and linear or branched C13 to C ₁₇ alkyl and alkenyl groups.

Advantageously, the hydrocarbon-based groups are linear.

Examples that may be mentioned include the compounds having formula (VIII) such as the diacyloxyethyldimethylammonium, diacyloxyethylhydroxyethyl- methylammonium, monoacyloxyethyldihydroxyethylmethylammonium, triacyloxyethylmethylammonium and monoacyloxyethylhydroxyethyldimethyl- ammonium salts (chloride or methyl sulfate in particular), and mixtures thereof. The acyl groups preferably contain 14 to 18 carbon atoms and are obtained more particularly from a plant oil such as palm oil or sunflower oil. When the compound contains several acyl groups, these groups may be identical or different. These products are obtained, for example, by direct esterification of triethanolamine, triisopropanolamine, alkyldiethanolamine or alkyldiisopropanolamine, which are optionally oxyalkylenated, with Cio to C30 fatty acids or with mixtures of Cio to C30 fatty acids of plant or animal origin, or by transesterification of their methyl esters. This esterification is followed by a quaternization using an alkylating agent such as an alkyl halide (preferably a methyl or ethyl halide), a dialkyl sulfate (preferably a dimethyl or diethyl sulfate), methyl methanesulfonate, methyl para-toluenesulfonate, glycol chlorohydrin or glycerol chlorohydrin.

Such compounds are sold, for example, under the names Dehyquart ^® by the company Henkel, Stepanquat ^® by the company Stepan, Noxamium ^® by the company CECA or Rewoquat ^® WE 18 by the company Rewo-Witco.

The composition according to the present invention may contain, for example, a mixture of quaternary ammonium monoester, diester and triester salts with a weight majority of diester salts.

It is also possible to use the ammonium salts containing at least one ester function that are described in patents US-A-4 874 554 and US-A-4 137 180.

Use may be made of behenoylhydroxypropyltrimethylammonium chloride sold by KAO under the name Quatarmin BTC 131.

Preferably, the ammonium salts comprising at least one ester function comprise two ester functions.

Among the quaternary ammonium salts containing at least one ester function, which may be used, it is preferred to use dipalmitoylethylhydroxyethyl- methylammonium salts.

The cationic surfactants are preferably chosen from those of formula (V) and those of formula (VIII) and even more preferentially from those of formula (V).

The composition according to the present invention may comprise one or more anionic surfactants.

The term "anionic surfactant" is intended to mean a surfactant comprising, as ionic or ionizable groups, only anionic groups. These anionic groups are preferably chosen from the groups -COOH, -COO ^" , -SO3H, -SO3 ^" , -OSO3H, -OSO3 ^" , -PO2H2, -PO2H-, -PO2 ^2" , -P(OH) ₂ , =P(0)OH, -P(OH)0 ^" , =P(0)0 ^" , =POH, =PO , the anionic parts comprising a cationic counterion such as those of an alkali metal, an alkaline-earth metal or an ammonium. As examples of anionic surfactants that may be used in the dye composition according to the invention, mention may be made of alkyl sulfates, alkyl ether sulfates, alkylamido ether sulfates, alkylaryl polyether sulfates, monoglyceride sulfates, alkylsulfonates, alkylamidesulfonates, alkylarylsulfonates, a-olefm sulfonates, paraffin sulfonates, alkyl sulfo succinates, alkyl ether sulfo succinates, alkylamide sulfosuccinates, alkyl sulfoacetates, acylsarcosinates, acylglutamates, alkyl sulfosuccinamates, acylisethionates and N-acyltaurates, polyglucoside- polycarboxylic acid and alkyl monoester salts, acyl lactylates, salts of D-galactoside uronic acids, salts of alkyl ether carboxylic acids, salts of alkylaryl ether carboxylic acids, salts of alkylamido ether carboxylic acids; and the corresponding non-salified forms of all these compounds; the alkyl and acyl groups of all these compounds comprising from 6 to 40 carbon atoms and the aryl group denoting a phenyl group.

These compounds may be oxyethylenated and then preferably comprise from 1 to 50 ethylene oxide units.

The salts of C ₆ to C ₂₄ alkyl monoesters of polyglucoside-polycarboxylic acids may be chosen from C ₆ to C ₂₄ alkyl polyglucoside-citrates, C ₆ -C ₂₄ alkyl polyglucoside-tartrates and C ₆ to C ₂₄ alkyl polyglucoside-sulfosuccinates.

When the anionic surfactant(s) are in salt form, they may be chosen from alkali metal salts such as the sodium or potassium salt and preferably the sodium salt, ammonium salts, amine salts and in particular amino alcohol salts or alkaline-earth metal salts such as the magnesium salts.

Examples of amino alcohol salts that may in particular be mentioned include monoethanolamine, diethanolamine and triethanolamine salts, monoisopropanolamine, diisopropanolamine or triisopropanolamine salts, 2-amino-2- methyl- 1-propanol salts, 2-amino-2-methyl-l,3-propanediol salts and tris(hydroxymethyl)aminomethane salts.

Use is preferably made of alkali metal or alkaline-earth metal salts and in particular of sodium or magnesium salts.

Among the anionic surfactants mentioned, use is preferably made of (C ₆ - C ₂₄ )alkyl sulfates, (C ₆ -C ₂₄ )alkyl ether sulfates comprising from 2 to 50 ethylene oxide units, in particular in the form of alkali metal, ammonium, amino alcohol and alkaline-earth metal salts, or a mixture of these compounds.

In particular, it is preferred to use (Ci ₂ -C ₂ o)alkyl sulfates, (Ci ₂ -C ₂ o)alkyl ether sulfates comprising from 2 to 20 ethylene oxide units, in particular in the form of alkali metal, ammonium, amino alcohol and alkaline-earth metal salts, or a mixture of these compounds. Better still, it is preferred to use sodium lauryl ether sulfate containing 2.2 mol of ethylene oxide.

The composition according to the present invention may comprise one or more amphoteric or zwitterionic surfactants.

In particular, the amphoteric or zwitterionic surfactant(s), which are preferably non-silicone, which may be used in the composition according to the present invention may in particular be derivatives of optionally quatemized aliphatic secondary or tertiary amines, in which derivatives the aliphatic group is a linear or branched chain comprising from 8 to 22 carbon atoms, said amine derivatives containing at least one anionic group, for instance a carboxylate, sulfonate, sulfate, phosphate or phosphonate group.

Mention may in particular be made of (Cs-C2o)alkyl betaines, (Cs-C2o)alkyl sulfobetaines, (C8-C2o)alkylamido(C3-C8)alkyl betaines and (C8-C2o)alkylamido(C6- C8)alkyl sulfobetaines.

Among the derivatives of optionally quatemized secondary or tertiary aliphatic amines that may be used, as defined above, mention may also be made of the compounds of respective structures (IX) and (X) below: Ra-CONHCH2CH2-N ⁺ (Rb)(Rc)-CH2COO-, M ⁺ , X ^" (IX) in which:

Ra represents a Cio to C30 alkyl or alkenyl group derived from an acid RaCOOH preferably present in hydrolysed coconut oil, or a heptyl, nonyl or undecyl group; - Rb represents a β-hydroxyethyl group; and

Rc represents a carboxymethyl group;

M ⁺ represents a cationic counterion derived from an alkali metal or alkaline- earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine; and

- X ^" represents an organic or inorganic anionic counterion, such as that chosen from halides, acetates, phosphates, nitrates, (Ci-C4)alkyl sulfates, (Ci-C4)alkyl- or (Ci-C4)alkylarylsulfonates, in particular methyl sulfate and ethyl sulfate; or alternatively M ⁺ and X ^" are absent; Ra<-CONHCH2CH2-N(B)(B') (X) in which:

B represents the group -CH2CH2OX';

- B' represents the group -(CH2) _Z Y', with z = 1 or 2;

- X ^* represents the group -CH2COOH, -CH2-COOZ', -CH2CH2COOH, -CH2CH2- COOZ', or a hydrogen atom;

- Y ^* represents the group -COOH, -COOZ', -CH ₂ CH(OH)S0 ₃ H or the group CH ₂ CH(OH)S0 ₃ -Z';

- Z' represents a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine;

Ra' represents a C10 to C ₃ o alkyl or alkenyl group of an acid Ra'-COOH which is preferably present in coconut oil or in hydrolysed linseed oil, or an alkyl group, in particular a C ₁₇ group, and its iso form, or an unsaturated C ₁₇ group.

These compounds are classified in the CTFA dictionary, 5th edition, 1993, under the names disodium cocoamphodiacetate, disodium lauroamphodiacetate, disodium caprylamphodiacetate, disodium caprylamphodiacetate, disodium cocoamphodipropionate, disodium lauroamphodipropionate, disodium caprylamphodipropionate, disodium caprylamphodipropionate, lauroamphodipropionic acid and cocoamphodipropionic acid.

Mention may be made, by way of example, of the cocoamphodiacetate sold by Rhodia under the trade name Miranol ^® C2M Concentrate.

Use may also be made of compounds of formula (XI): Ra"-NHCH(Y")-(CH2)nCONH(CH ₂ )n'-N(Rd)(Re) (XI) in which:

- Y" represents the group -COOH, -COOZ" or -CH ₂ -CH(OH)S0 ₃ H or the group CH ₂ CH(OH)S0 ₃ -Z";

- Rd and Re, independently of each other, represent a Ci to C ₄ alkyl or hydroxyalkyl radical;

Z" represents a cationic counterion derived from an alkali metal or alkaline-earth metal, such as sodium, an ammonium ion or an ion derived from an organic amine; Ra" represents a C10-C30 alkyl or alkenyl group of an acid Ra"-COOH which is preferably present in coconut oil or in hydrolysed linseed oil;

n and n' denote, independently of each other, an integer ranging from 1 to 3.

Mention may be made, among the compounds of formula (XI), of the compound classified in the CTFA dictionary under the name sodium diethylaminopropyl cocoaspartamide and sold by Chimex under the name Chimexane HB.

These compounds may be used alone or as mixtures.

Among the amphoteric or zwitterionic surfactants mentioned above, use is preferably made of (C8-C2o)alkylbetaines such as cocobetaine, (C ₈ - C2o)alkylamido(C3-C8)alkylbetaines such as cocamidopropylbetame, and mixtures thereof, and the compounds of formula (XI) such as the sodium salt of diethylaminopropyl laurylaminosuccinamate (INCI name: sodium diethylaminopropyl cocoaspartamide).

Preferably, the surfactant(s) is (are) chosen from non- ionic surfactants, and more preferentially from oxyethylenated (20E) lauryl alcohol, oxyethylenated (40E) sorbitan monolaurate, oxyethylenated (30OE) cetylstearyl alcohol, oxyethylenated (20E) (C13-C15) alkyl acid monoethanolamide, and mixtures thereof.

The amount of surfactant(s), when it (they) is (are) present in the composition according to the invention, preferably ranges from 0.1% to 15% by weight and more preferentially from 0.5% to 10% by weight, relative to the total weight of the composition.

Alkaline agents

The composition according to the present invention may optionally also comprise one or more alkaline agents.

The alkaline agent(s) may be mineral, organic or hybrid.

The mineral alkaline agent(s) are preferably chosen from aqueous ammonia, alkali metal carbonates or bicarbonates such as sodium or potassium carbonates and sodium or potassium bicarbonates, sodium hydroxide or potassium hydroxide, or mixtures thereof.

The organic alkaline agent(s) are preferably chosen from organic amines with a pKb at 25°C of less than 12, preferably less than 10 and even more advantageously less than 6. It should be noted that it is the pKb corresponding to the function of highest basicity. In addition, the organic amines do not comprise any alkyl or alkenyl fatty chain comprising more than ten carbon atoms.

The organic alkaline agent(s) are chosen, for example, from alkanolamines, oxyethylenated and/or oxypropylenated ethylenediamines, amino acids and the compounds having formula (XII) below:

^R *\ N - W - N A

/ \

^R y ^ (xii) in which W is a divalent Ci to C ₆ alkylene radical optionally substituted with one or more hydroxyl groups or a Ci to C ₆ alkyl radical, and/or optionally interrupted with one or more heteroatoms such as O, or NR _U ; R _x , R _y , R _z , Rt and R _u , which may be identical or different, represent a hydrogen atom or a Ci to C ₆ alkyl, Ci to C ₆ hydroxyalkyl or Ci to C ₆ aminoalkyl radical.

The term "alkanolamine" is intended to mean an organic amine comprising a primary, secondary or tertiary amine function, and one or more linear or branched Ci- C8 alkyl groups bearing one or more hydroxyl radicals.

Organic amines chosen from alkanolamines such as monoalkanolamines, dialkanolamines or trialkanolamines comprising one to three identical or different Ci- C ₄ hydroxyalkyl radicals are in particular suitable for performing the invention.

Among the compounds of this type, mention may be made of monoethanolamine (MEA), diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Ν,Ν-dimethylethanolamine, 2-amino-2- methyl-l-propanol, triisopropanolamine, 2-amino-2-methyl-l ,3-propanediol, 3- amino-l ,2-propanediol, 3-dimethylamino-l ,2-propanediol and tris(hy droxymethy l)amino methane .

More particularly, the amino acids that may be used are of natural or synthetic origin, in their L, D or racemic form, and comprise at least one acid function chosen more particularly from carboxylic acid, sulfonic acid, phosphonic acid and phosphoric acid functions. The amino acids may be in neutral or ionic form.

As amino acids that may be used in the composition according to the present invention, mention may be made in particular of aspartic acid, glutamic acid, alanine, arginine, ornithine, citrulline, asparagine, carnitine, cysteine, glutamine, glycine, histidine, lysine, isoleucine, leucine, methionine, N-phenylalanine, proline, serine, taurine, threonine, tryptophan, tyrosine and valine.

Advantageously, the amino acids are basic amino acids comprising an additional amine function optionally included in a ring or in a ureido function.

Such basic amino acids are preferably chosen from those corresponding to formula (XIII) below, and also salts thereof:

R-CH ₂ -CH(NH ₂ )-C(0)-OH (XIII) in which R represents a group chosen from imidazolyl, preferably imidazolyl-4-yl; aminopropyl; aminoethyl; -(CH ₂ ) ₂ N(H)-C(0)-NH ₂ ; and -(CH ₂ ) ₂ -N(H)-C(NH)-NH ₂ .

The compounds corresponding to formula (XIII) are histidine, lysine, arginine, ornithine and citrulline.

The organic amine may also be chosen from organic amines of heterocyclic type. Besides histidine that has already been mentioned in the amino acids, mention may in particular be made of pyridine, piperidine, imidazole, triazole, tetrazole and benzimidazole.

The organic amine may also be chosen from amino acid dipeptides. As amino acid dipeptides that may be used in the present invention, mention may be made in particular of carnosine, anserine and balenine.

The organic amine may also be chosen from compounds comprising a guanidine function. As amines of this type that may be used in the present invention, besides arginine, which has already been mentioned as an amino acid, mention may be made in particular of creatine, creatinine, 1,1-dimethylguanidine, 1,1- diethylguanidine, glycocyamine, metformin, agmatine, n-amidinoalanine, 3- guanidinopropionic acid, 4-guanidinobutyric acid and 2- ([amino(imino)methyl]amino)ethane- 1 -sulfonic acid.

Hybrid compounds that may be mentioned include the salts of the amines mentioned previously with acids such as carbonic acid or hydrochloric acid.

Guanidine carbonate or monoethanolamine hydrochloride may be used in particular.

Preferably, the alkaline agent(s) present in the composition according to the invention are chosen from aqueous ammonia, alkanolamines, amino acids in neutral or ionic form, in particular basic amino acids, and preferably corresponding to those having formula (XIII).

More preferentially, the alkaline agent(s) present in the composition according to the invention is (are) chosen from aqueous ammonia, alkanolamines, and mixtures thereof.

The alkaline agent(s) are introduced in a content such that the pH of the composition according to the invention is advantageously between 8 and 12, and more preferentially between 8.5 and 10.5.

Organic solvents

The composition according to the present invention may optionally also comprise one or more organic solvents.

Examples of organic solvents that may be mentioned include linear or branched C ₂ to C ₄ alkanols, such as ethanol and isopropanol; glycerol; polyols and polyol ethers, for instance 2-butoxyethanol, propylene glycol, hexylene glycol, dipropylene glycol, propylene glycol monomethyl ether, diethylene glycol mo no methyl ether and monoethyl ether, and also aromatic alcohols or ethers, for instance benzyl alcohol or phenoxy ethanol, and mixtures thereof.

Additives

The composition according to the present invention may also optionally comprise one or more additives, different from the compounds of the invention and among which mention may be made of cationic, anionic, nonionic or amphoteric polymers or mixtures thereof, antidandruff agents, anti-seborrhoea agents, agents for preventing hair loss and/or for promoting hair regrowth, vitamins and provitamins including panthenol, sunscreens, mineral or organic pigments, sequestrants, plasticizers, solubilizers, acidifying agents, mineral or organic thickeners, in particular polymeric thickeners, opacifiers or nacreous agents, antioxidants, hydroxy acids, fragrances, preserving agents, pigments and ceramides.

Needless to say, 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 according to the invention are not, or are not substantially, adversely affected by the envisaged addition(s).

The above additives may generally be present in an amount comprised, for each of them, of between 0 and 20% by weight relative to the total weight of the ready-to-use composition. Bleaching process

A subject of the present invention is also a process for treating, preferably lightening, keratin materials, in particular keratin fibres, and in particular human keratin fibres such as the hair, using one or more compounds of formula (I) or (II) as defined previously, and also the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof, preferably in the presence of one or more chemical oxidizing agents.

The present invention also relates to a process for lightening keratin materials, in particular keratin fibres, and in particular human keratin fibres such as the hair, consisting in applying to said keratin materials a composition as defined previously.

In particular, the composition used in the process of the invention is applied to wet or dry keratin fibres.

The composition is advantageously left to stand on the keratin fibres for a time ranging from 1 minute to 1 hour and more preferentially for a time ranging from 5 to 45 minutes.

On the conclusion of the dyeing process, the keratin fibres are advantageously rinsed with water. They may optionally be washed with a shampoo, followed by rinsing with water, before being dried or left to dry.

Use

The present invention also relates to the use of one or more compounds of formula (I) or (II) as defined previously, and also the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof, for treating keratin materials, in particular keratin fibres, and in particular human keratin fibres such as the hair.

Compounds of formula (III) or (IV)

The present invention also relates to a double pyridinium compound of formula (III) or (IV) as defined previously, and also to the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof.

Preferably, the double pyridinium compound(s) of formula (III) or (IV) is (are) chosen from compounds (1) to (15), as defined previously, and also the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof.

The compounds of formula (III) according to the present invention may in particular be obtained using a general procedure described in reaction scheme 1

Reaction scheme 1

According to this procedure, the compounds of formula (III) are obtained by quatemization of pyridine derivatives (1) with alkylating reagents (2). This reaction generally takes place in the presence of a solvent, for instance ethanol, and can be accelerated by heating.

The compounds of formula (III) of the invention may also be obtained by simple counteranion exchange with an anion salt as described in reaction scheme 2 below.

Reaction scheme 2 The compounds of formula (IV) according to the present invention may in particular be obtained using a general procedure described in reaction scheme 3 below.

Anion

Reaction scheme 3

According to this procedure, the compounds of formula (IV) are obtained by quatemization of pyridine derivatives (1) with alkylating reagents (2). This reaction generally takes place in the presence of a solvent, for instance ethanol, and can be accelerated by heating.

The compounds of formula (IV) of the invention may also be obtained by simple counteranion exchange with an anion salt as described in reaction scheme 4 below.

Reaction scheme 4 More particularly, the compounds of formulae (I) and (II) may be obtained on the basis of reactions described in the literature and more specifically on the basis of the following literature references: EP 219 281; Journal of Pharmaceutical Sciences (1962), 51, 27-31; Chemical & Pharmaceutical Bulletin (1973), 21(3), 634- 8; and Polyhedron (1988), 7(1), 43-7.

The present invention finally relates to a cosmetic composition comprising one or more compounds of formula (III) or (IV), as defined previously, and also to the addition salts thereof, optical isomers thereof, geometrical isomers thereof, tautomers thereof, solvates thereof and mixtures thereof; and preferably also one or more chemical oxidizing agents.

The examples that follow serve to illustrate the invention without, however, being limiting in nature.

In these examples, the colour of the locks was evaluated in the CIE L* a* b* system, using a Minolta Spectrophotometer CM2600D colorimeter.

In this L* a* b* system, the three parameters denote, respectively, the colour intensity (L*), the green/red colour axis (a*) and the blue/yellow colour axis (b*). The higher the value of L*, the lighter the colour. The higher the value of a*, the redder the colour and the higher the value of b*, the yellower the colour.

EXAMPLES I . SYNTHESIS EXAMPLES

Example 1 : synthesis of 1,1 ' -butane- 1 ,4-diylbis(4-acetylpyridinium) dibromide

9.91 g (41 mmol, leq) of 1 ,4-dibromobutane are added to 10 g (83 mmol, 2eq) of 4-acetylpyridine in solution in 35 ml of toluene with stirring. The mixture is heated at 90°C for 7 hours and then left to cool at ambient temperature.

The precipitate formed is filtered off under vacuum and under argon, then washed with toluene and with diisopropyl ether.

8.7 g, equivalent to a yield of 46%, of 1,1 '-butane- 1 ,4-diylbis(4- acetylpyridinium) dibromide are obtained. The NMR and mass spectrometry analyses are in accordance with the expected structure.

Example 2: Synthesis of 3,3'-[ethane-l,2-diylbis(iminomethanediyl)]bis[l- (carboxymethyl)pyridinium] dichloride

· Step 1 : synthesis of N,N'-bis[l-pyridin-3-ylmeth-(E)-ylidene]ethane-l,2- diamine, compound (a)

10 g (93.5 mmol) of 3-pyridinecarboxaldehyde are dissolved in 100 ml of methanol. 2.8 g (4.6 mmol) of 1 ,2-ethyldiamine are added and the whole mixture is heated for 30 minutes at 80°C.

After evaporation to dryness, the oil is precipitated from diethyl ether. 5.2 g, equivalent to a yield of 47%, of compound (a) are obtained in the form of a white powder.

The NMR and mass spectroscopy analyses are in accordance with the expected structure. • Step 2: synthesis of N,N'-bis-pyridin-3-ylmethylethane-l,2-diamine, compound (b)

1.8 g (47.6 mmol) of NaBH ₄ are slowly added to a solution containing 11 g

(46.2 mmol) of compound (a) in 200 ml of ethanol. The mixture is then stirred at ambient temperature for 1 hour.

After evaporation to dryness, 150 ml of water are added to the reaction crude. The latter is then acidified to a pH of 1 with 20 ml of concentrated HCl. The mixture is stirred for 1 hour and the pH is then brought back to 9.5.

The aqueous phase is extracted with CH2CI2 and washed with a saturated aqueous salt solution. The organic phase is then dried and evaporated to dryness. The oil obtained is dissolved in 40 ml of water and acidified with an HCl solution. The product is precipitated after addition of 100 ml of ethanol.

9.3 g, equivalent to a yield of 51.8%, of compound (b) are obtained in the form of a white powder.

The NMR and mass spectrometry analyses are in accordance with the expected structure. · Step 3 : synthesis of 3,3'-[ethane-l,2-diylbis(iminomethanediyl)]bis[l-

(carboxymethyl)pyridinium] dichloride

A solution containing 2g (7.2 mmol) of compound (b) in 20 ml of water is basified with NaHC0 ₃ until a pH of 10.5 is obtained. 2 g (14.4 mmol) of bromoacetic acid and 1.2 g of NaHC0 ₃ (14.4 mmol) in solution in 15 ml of water are then added. The whole mixture is heated at 40°C for 20 hours and the pH is maintained at 11.

At the end of the reaction, the solution is acidified so as to obtain a pH of 4.5, then concentrated. 100 ml of ethanol are then added and a precipitate is filtered off, washed with ethanol and dried under vacuum.

2.1 g, equivalent to a yield of 68%, of 3,3'-[ethane-l,2- diylbis(iminomethanediyl)]bis[l-(carboxymethyl)pyridinium] dichloride are obtained in the form of white powder.

The NMR spectrometry analyses are in accordance with the expected structure.

Example 3: Synthesis of lJ ^, -bis(2-oxopropyl)-4,4'-bipyridinium dichloride

4 g (25.6 mmol, leq) of 4,4'-bipyridine are suspended in 20ml of absolute ethanol.

6.12 ml (76.8 mmol, 3eq) of chloroacetone are added, then the whole mixture is refluxed for 7 hours before being left at ambient temperature.

A precipitate is filtered off under vacuum, from diisopropyl ether and under argon, and then washed with diisopropyl ether. The powder is then dried under vacuum over P2O5.

The crude product is dissolved in methanol (500 ml) and re-precipitated from 1.7 1 of acetone.

4 g, equivalent to a yield of 46%, of l, -bis(2-oxopropyl)-4,4'-bipyridinium dichloride are obtained.

The NMR and mass spectrometry analyses are in accordance with the expected structure. II . DYEING EVALUATIONS a) Compositions

Composition (A) and oxidizing composition (B) were prepared from the ingredients of which the contents are indicated, as weight percentage of active material relative to the total weight of composition (A) or (B), in the tables below.

Composition (A)

Oxidizing composition (B)

Compositions (A) and (B) thus obtained are then mixed in a 1 : 1.5 ratio in the presence or absence of dye in order to prepare composition (1) according to the invention and comparative composition (2).

b) Procedure

Compositions (1) and (2) thus obtained are then applied to locks of natural hair of 250 mg having a tone depth of 4. After a leave-on time of 30 minutes at 27°C, the locks are washed with a standard shampoo, rinsed and dried.

The colorimetric data of each of the locks are then measured with a Minolta CM-3610d spectrophotometer: c) Results

The results are given in the table below.

The results obtained above show that composition (1) according to the invention makes it possible to obtain better lightness (L*), that is to say better lightening, than comparative composition (2).

More particularly, the presence of 1,1 '-butane- 1 ,4-diylbis-(4- acetylpyridinium) dibromide makes it possible to improve the oxidizing power of hydrogen peroxide and thus to boost its activity. a) Compositions

Composition A and oxidizing composition B were prepared from the ingredients mentioned in Example 1. Compositions (A) and (B) thus obtained are then mixed in a 1 : 1.5 ratio in the presence or absence of dye in order to prepare compositions (3) and (4) according to the invention and comparative composition (5).

b) Procedure

Compositions (3), (4) and (5) thus obtained are then applied to locks of natural hair of 250 mg having a tone depth of 4. After a leave-on time of 30 minutes at 27°C, the locks are washed with a standard shampoo, rinsed and dried.

The colorimetric data of each of the locks are then measured with a Minolta

CM-3610d spectrophotometer. c) Results

The results are given in the table below.

Composition 3 Composition 4 Composition 5 invention invention comparative

Lightness (L*) 26 27 25 The results obtained above show that compositions (3) and (4) according to the invention make it possible to obtain better lightness (L*), that is to say better lightening, than comparative composition (5).

More particularly, the presence of double pyridinium compounds, such as 3,3'-[ethane-l,2-diylbis-(iminomethanediyl)]bis[l-(carboxyme thyl)pyridinium] dichloride (composition 3) and l, -bis(2-oxopropyl)-4,4'-bipyridinium dichloride (composition 4), makes it possible to improve the oxidizing power of hydrogen peroxide and thus to boost its activity.