Cosmetic composition including at least one silicone-grafted polymer and at least one polysiloxane-polyoxyalkylene linear block copolymer

[0002] The present invention relates to a cosmetic or dermatological composition for treating keratin substances, in particular human hair, this composition comprising at least one grafted silicone polymer and at least one copolymer having a linear polysiloxane/polyoxyalkylene block as repeating units.

[0003] Grafted silicone polymers are known in the prior art, such as those described in patent applications EP-A-0,412,704, EP-A-0,412,707, EP-A-0,640,105, WO 95/00578, EP-A-0,582,152 and WO 93/23009. These polymers are used in hair care for their styling properties. However, when these polymers are used, the fixing power, the hold of the hairstyle and the feel of the hair are still unsatisfactory.

[0004] The expression fixing power of the composition will be understood to denote the ability of this composition to give the hair cohesion such that the initial shape of the hairstyle is held.

[0005] Silicones are known which possess grafted polyoxyalkylene chains, also known as dimethicone copolyol according to the CTFA nomenclature. The Applicant has observed that these silicones lower the fixing power of compositions for holding the hairstyle.

[0006] The Applicant has discovered, surprisingly, that by combining at least one grafted silicone polymer with at least one copolymer having a linear polysiloxane/polyoxyalkylene block as repeating units, the fixing power of the compositions and the feel of the hair are substantially superior to those obtained with the grafted silicone polymer used alone.

[0007] The composition according to the invention is thus essentially characterized in that it contains, in a cosmetically or dermatologically acceptable medium, at least one grafted silicone polymer comprising a polysiloxane portion and a portion consisting of a non-silicone organic chain, one of the two portions constituting the main chain of the polymer, the other being grafted onto the said main chain, and at least one copolymer having a linear polysiloxane/polyoxyalkylene block as repeating units.

[0008] The grafted silicone polymers according to the invention are preferably chosen from polymers having a non-silicone organic skeleton grafted with monomers containing a polysiloxane, polymers having a polysiloxane skeleton grafted with non-silicone organic monomers and mixtures thereof.

[0009] In the following text, in accordance with what is generally accepted, the term silicone or polysiloxane is understood to denote any organosilicon polymer or oligomer having a linear or cyclic, branched or crosslinked structure of variable molecular weight, obtained by polymerization and/or polycondensation of suitably functionalized silanes, and consisting essentially of a repetition of main units in which the silicon atoms are linked together by oxygen atoms (siloxane bonding ≡Si—O—Si≡), optionally substituted hydrocarbon radicals being linked directly via a carbon atom to the said silicon atoms. The most common hydrocarbon radicals are alkyl radicals, especially C₁-C₁₀alkyl radicals, and in particular methyl, fluoroalkyl radicals, aryl radicals and in particular phenyl, and alkenyl radicals and in particular vinyl; other types of radicals which can be linked, either directly or via a hydrocarbon radical, to the siloxane chain are, especially, hydrogen, halogens and in particular chlorine, bromine or fluorine, thiols, alkoxy radicals, polyoxyalkylene (or polyether) radicals and in particular polyoxyethylene and/or polyoxypropylene, hydroxyl or hydroxyalkyl radicals, substituted or unsubstituted amine groups, amide groups, acyloxy radicals or acyloxyalkyl radicals, hydroxyalkylamino or aminoalkyl radicals, quaternary ammonium groups, amphoteric or betaine groups, anionic groups such as carboxylates, thioglycolates, sulphosuccinates, thiosulphates, phosphates and sulphates, needless to say this list not being limiting in any way (so-called “organomodified” silicones).

[0010] In the following text, in accordance with what is generally accepted, the expression “polysiloxane macromer” is understood to refer to any monomer containing a polysiloxane-type polymer chain in its structure.

[0011] The polymers containing a non-silicone organic skeleton grafted with monomers containing a polysiloxane, in accordance with the present invention, consist of an organic main chain formed from organic monomers containing no silicone, on which is grafted, inside the said chain and optionally on at least one of its ends, at least one polysiloxane macromer.

[0012] The non-silicone organic monomers constituting the main chain of the grafted silicone polymer can be chosen from monomers containing ethylenic unsaturation which are polymerizable via a radical route, monomers which are polymerizable by polycondensation, such as those forming polyamides, polyesters or polyurethanes, and monomers which involve ring opening, such as those of the oxazoline or caprolactone type.

[0013] The polymers containing a non-silicone organic skeleton grafted with monomers containing a polysiloxane, in accordance with the present invention, can be obtained according to any means known to those skilled in the art, in particular by reaction between (i) a starting polysiloxane macromer which is correctly functionalized on the polysiloxane chain and (ii) one or more non-silicone organic compounds, themselves correctly functionalized with a function which is capable of reacting with the functional group(s) borne by the said silicone, forming a covalent bond; a classic example of such a reaction is the radical reaction between a vinyl group borne on one of the ends of the silicone with a double bond of a monomer containing ethylenic unsaturation in the main chain.

[0014] The polymers containing a non-silicone organic skeleton grafted with monomers containing a polysiloxane, in accordance with the invention, are more preferably chosen from those described in U.S. Pat. Nos. 4,693,935, 4,728,571 and 4,972,037 and patent applications EP-A-0,412,704, EP-A-0,412,707, EP-A-0,640,105 and WO 95/00578. These are copolymers obtained by radical polymerization starting with monomers containing ethylenic unsaturation and silicone macromers having a terminal vinyl group, or alternatively copolymers obtained by reaction of a polyolefin comprising functionalized groups and a polysiloxane macromer having a terminal function which is reacted with the said functionalized groups.

[0015] One particular family of grafted silicone polymers which is suitable for carrying out the present invention consists of silicone grafted copolymers comprising:

[0016] a) from 0 to 98% by weight of at least one lipophilic monomer (A) of low lipophilic polarity containing ethylenic unsaturation, which is polymerizable via a radical route;

[0017] b) from 0 to 98% by weight of at least one polar hydrophilic monomer (B) containing ethylenic unsaturation, which is copolymerizable with the (A)-type monomer(s);

[0018] c) from 0.01 to 50% by weight of at least one polysiloxane macromer (C) of general formula:

[0019] X(Y)_nSi(R)_3−mZ_m  (I)

[0020] where:

[0021] X denotes a vinyl group which is copolymerizable with the monomers (A) and (B);

[0022] Y denotes a divalent bonding group;

[0023] R denotes a hydrogen, a C₁-C₆alkyl or alkoxy or a C₆-C₁₂aryl;

[0024] Z denotes a monovalent polysiloxane unit having a number-average molecular weight of at least 500;

[0025] n is 0 or 1 and m is an integer ranging from 1 to 3;

[0026] the percentages being calculated relative to the total weight of the monomers (A), (B) and (C).

[0027] These polymers are described, along with processes for their preparation, in U.S. Pat. Nos. 4,693,935, 4,728,571 and 4,972,037 and in patent applications EP-A-0,412,704, EP-A-0,412,707 and EP-A-0,640,105. They have a number-average molecular weight preferably ranging from 10,000 to 2,000,000 and preferably a glass transition temperature Tg or a crystalline melting point Tm of at least −20° C.

[0028] As examples of lipophilic monomers (A), mention may be made of acrylic or methacrylic acid esters of C₁-C₁₈alcohols; styrene; polystyrene macromers; vinyl acetate; vinyl propionate; a-methylstyrene; tert-butylstyrene; butadiene; cyclohexadiene; ethylene; propylene; vinyltoluene; acrylic or methacrylic acid esters of 1,1-dihydroperfluoroalkanols or of homologues thereof; acrylic or methacrylic acid esters of ω-hydridofluoroalkanols; acrylic or methacrylic acid esters of fluoroalkylsulphoamido alcohols; acrylic or methacrylic acid esters of fluoroalkyl alcohols; acrylic or methacrylic acid esters of fluoroether alcohols; or mixtures thereof. The preferred monomers (A) are chosen from the group consisting of n-butyl methacrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, methyl methacrylate, 2-(N-methylperfluorooctanesulphonamido)ethyl acrylate and 2-(N-butylperfluorooctanesulphonamido)ethyl acrylate, and mixtures thereof.

[0029] As examples of polar monomers (B), mention may be made of acrylic acid, methacrylic acid, N,N-dimethylacrylamide, dimethylaminoethyl methacrylate, quaternized dimethylaminoethyl methacrylate, (meth)acrylamide, N-t-butylacrylamide, maleic acid, maleic anhydride and semiesters thereof, hydroxyalkyl (meth)acrylates, diallyldimethylammonium chloride, vinylpyrrolidone, vinyl ethers, maleimides, vinylpyridine, vinylimidazole, heterocyclic vinyl polar compounds, styrene sulphonate, allyl alcohol, vinyl alcohol and vinyl caprolactam, or mixtures thereof. The preferred monomers (B) are chosen from the group consisting of acrylic acid, N,N-dimethylacrylamide, dimethylaminoethyl methacrylate, quaternized dimethylaminoethyl methacrylate and vinylpyrrolidone, and mixtures thereof.

[0030] The preferred polysiloxane macromers (C) of formula (I) are chosen from those corresponding to the general formula (II) below:

[0031] in which:

[0032] R¹is hydrogen or —COOH (preferably hydrogen);

[0033] R²is hydrogen, methyl or —CH₂COOH (preferably methyl);

[0034] R³is C₁-C₆alkyl, alkoxy, or alkylamino, C₆-C₁₂aryl or hydroxyl (preferably methyl);

[0035] R⁴is C₁-C₆alkyl, alkoxy or alkylamino, C₆-C₁₂aryl or hydroxyl (preferably methyl);

[0036] q is an integer from 2 to 6 (preferably 3);

[0037] p is 0 or 1;

[0038] r is an integer from 5 to 700;

[0039] m is an integer from 1 to 3 (preferably 1).

[0040] The polysiloxane macromers of formula:

[0041] with n being an integer ranging from 5 to 700, are more particularly used.

[0042] One particular embodiment of the invention consists in using a copolymer which can be obtained by radical polymerization starting with the monomer mixture consisting of:

[0043] a) 60% by weight of tert-butyl acrylate;

[0044] b) 20% by weight of acrylic acid;

[0045] c) 20% by weight of silicone macromer of formula:

[0046] with n being an integer ranging from 5 to 700; the weight percentages being calculated relative to the total weight of the monomers.

[0047] Another particular embodiment of the invention consists in using a copolymer which can be obtained by radical polymerization starting with the monomer mixture consisting of:

[0048] a) 80% by weight of tert-butyl acrylate;

[0049] b) 20% by weight of silicone macromer of formula:

[0050] with n being an integer ranging from 5 to 700; the weight percentages being calculated relative to the total weight of the monomers.

[0051] Another particular family of grafted silicone polymers containing a non-silicone organic skeleton, which is suitable for carrying out the present invention, consists of silicone grafted copolymers which can be obtained by reactive extrusion of a polysiloxane macromer having a terminal reactive function, with a polyolefin-type polymer containing reactive groups which can react with the terminal function of the polysiloxane macromer in order to form a covalent bond allowing grafting of the silicone to the main chain of the polyolefin.

[0052] These polymers are described, along with a process for their preparation, in patent application WO 95/00578.

[0053] The reactive polyolefins are preferably chosen from polyethylenes or polymers of ethylene-derived monomers such as propylene, styrene, alkylstyrene, butylene, butadiene, (meth)acrylates, vinyl esters or equivalents, containing reactive functions which can react with the terminal function of the polysiloxane macromer. They are chosen more particularly from copolymers of ethylene or of ethylene derivatives and of monomers chosen from those containing a carboxylic function, such as (meth)acrylic acid; those containing an acid anhydride function such as maleic anhydride; those containing an acid chloride function such as (meth)acryloyl chloride; those containing an ester function such as (meth)acrylic acid esters; those containing an isocyanate function.

[0054] The silicone macromers are preferably chosen from polysiloxanes containing a functionalized group, at the end of the polysiloxane chain or close to the end of the said chain, chosen from the group consisting of alcohols, thiols, epoxy groups and primary and secondary amines, and more particularly from those corresponding to the general formula:

[0055] T—(CH₂)_s—Si—[(O—SiR⁵R⁶)_t—R⁷]_y  (III)

[0056] in which T is chosen from the group consisting of NH₂, NHR′, an epoxy, OH, or SH function; R⁵, R⁶, R⁷and R′, independently denote a C₁-C₆alkyl, phenyl, benzyl, C₆-C₁₂alkylphenyl or hydrogen; s is a number from 2 to 100; t is a number from 0 to 1000 and y is a number from 1 to 3. They have a number-average molecular weight preferably ranging from 5000 to 300,000, more preferably from 8000 to 200,000 and more particularly from 9000 to 40,000.

[0057] According to the present invention, the grafted silicone polymer(s) containing a polysiloxane skeleton grafted with non-silicone organic monomers comprise a silicone (or polysiloxane (≡Si—O—)_n) main chain on which is grafted, inside the said chain as well as, optionally, on at least one of its ends, at least one organic group containing no silicone.

[0058] The polymers containing a polysiloxane skeleton grafted with non-silicone organic monomers, according to the invention, can be existing commercial products or alternatively can be obtained according to any means known to those skilled in the art, in particular by reaction between (i) a starting silicone which is correctly functionalized on one or more of these silicon atoms, and (ii) a non-silicone organic compound which is itself correctly functionalized with a function which is capable of reacting with the functional group(s) borne by the said silicone, forming a covalent bond; a classic example of such a reaction is the hydrosilylation reaction between ≡Si—H groups and vinyl groups CH₂═CH—, or alternatively the reaction between thio functional groups —SH with these same vinyl groups.

[0059] Examples of polymers with a polysiloxane skeleton grafted containing non-silicone organic monomers which are suitable for carrying out the present invention, as well as their specific mode of preparation, are described in particular in patent applications EP-A-0,582,152, WO 93/23009 and WO 95/03776, the teachings of which are included in, their entirety in the present description by way of non-limiting references.

[0060] According to a particularly preferred embodiment of the present invention, the silicone polymer containing a polysiloxane skeleton grafted with non-silicone organic monomers, which is used comprises the result of the radical copolymerization between, on the one hand, at least one non-silicone anionic organic monomer having ethylenic unsaturation and/or a non-silicone hydrophobic organic monomer having ethylenic unsaturation, and, on the other hand, a silicone having in its chain at least one, and preferably several, functional groups capable of reacting with the said ethylenic unsaturations of the said non-silicone monomers, forming a covalent bond, in particular thio functional groups.

[0061] According to the present invention, the said anionic monomers containing ethylenic unsaturation are preferably chosen, alone or as a mixture, from linear or branched, unsaturated carboxylic acids, optionally partially or totally neutralized in the form of a salt, it being possible for this (these) carboxylic acid(s) to be, more particularly, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid and crotonic acid. The suitable salts are, in particular, alkali metal salts, alkaline-earth metal salts and ammonium salts. It will likewise be noted that, in the final grafted silicone polymer, the organic group of anionic nature which comprises the result of the radical (homo)polymerization of at least one anionic monomer of unsaturated carboxylic acid type can, after reaction, be post-neutralized with a base (sodium hydroxide, aqueous ammonia, etc) in order to bring it into the form of a salt.

[0062] According to the present invention, the hydrophobic monomers containing ethylenic unsaturation are preferably chosen, alone or as a mixture, from acrylic acid esters of alkanols and/or methacrylic acid esters of alkanols. The alkanols are preferably C₁-C₁₈and more particularly C₁-C₁₂. The preferred monomers are chosen from the group consisting of isooctyl (meth)acrylate, isononyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, isopentyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, methyl (meth)acrylate, tert-butyl (meth)acrylate, tridecyl (meth)acrylate and stearyl (meth)acrylate, or mixtures thereof.

[0063] One family of silicone polymers containing a polysiloxane skeleton grafted with non-silicone organic monomers which is particularly suitable for carrying out the present invention consists of silicone polymers containing in their structure the unit of formula (IV) below:

[0064] in which the radicals G₁, which may be identical or different, represent hydrogen or a C₁-C₁₀alkyl radical or alternatively a phenyl radical; the radicals G₂, which may be identical or different, represent a C₁-C₁₀alkylene group; G₃represents a polymer residue resulting from the (homo)polymerization of at least one anionic monomer containing ethylenic unsaturation; G₄represents a polymer residue resulting from the (homo)polymerization of at least one hydrophobic monomer containing ethylenic unsaturation; m and n are equal to 0 or 1; a is an integer ranging from 0 to 50; b is an integer which may be between 10 and 350, c is an integer ranging from 0 to 50; with the proviso that one of the parameters a and c is other than 0.

[0065] Preferably, the unit of formula (IV) above has at least one, and even more preferably all, of the following characteristics:

[0066] the radicals G₁denote an alkyl radical, preferably the methyl radical;

[0067] n is non-zero and the radicals G₂represent a divalent C₁-C₃radical, preferably a propylene radical;

[0068] G₃represents a polymeric radical resulting from the (homo)polymerization of at least one monomer of the carboxylic acid type containing ethylenic unsaturation, preferably acrylic acid and/or methacrylic acid;

[0069] G₄represents a polymeric radical resulting from the (homo)polymerization of at least one monomer of the C₁-C₁₀alkyl (meth)acrylate type, preferably isobutyl or methyl (meth)acrylate.

[0070] Examples of silicone polymers corresponding to formula (IV) are, in particular, polydimethylsiloxanes (PDMS) on which are grafted, via a thiopropylene-type connecting chain, mixed polymer units of the poly(meth)acrylic acid type and of the polymethyl (meth)acrylate type.

[0071] Other examples of silicone polymers corresponding to formula (IV) are, in particular, polydimethylsiloxanes (PDMS) on which are grafted, via a thiopropylene-type connecting chain, polymer units of the polyisobutyl (meth)acrylate type.

[0072] Preferably, the number-average molecular mass of the silicone polymers containing a polysiloxane skeleton grafted with non-silicone organic monomers, of the invention, ranges approximately from 10,000 to 1,000,000 and even more preferably approximately from 10,000 to 100,000.

[0073] The grafted silicone polymers in accordance with the invention are preferably used in an amount ranging from 0.01 to 20% by weight relative to the total weight of the composition. More preferably, this amount ranges from 0.1 to 15% by weight and even more particularly from 0.5 to 10% by weight.

[0074] The block copolymers having a linear polysiloxane/polyoxyalkylene block as repeating units, which are used in the context of the present invention, preferably have the following general formula:

[0075] ([Y(R₂siO)_aR′₂SiYO][(C_nH_2nO)_b])₂  (V)

[0076] in which:

[0077] R and R′, which may be identical or different, represent a monovalent hydrocarbon radical containing no aliphatic unsaturation,

[0078] n is an integer ranging from 2 to 4,

[0079] a is an integer greater than or equal to 5, preferably between 5 and 200 and even more particularly between 5 and 100,

[0080] b is an integer greater than or equal to 4, preferably between 4 and 200 and even more particularly between 5 and 100,

[0081] c is an integer greater than or equal to 4, preferably between 4 and 1000 and even more particularly between 5 and 300,

[0082] Y represents a divalent organic group which is linked to the adjacent silicon atom via a carbon-silicon bond and to a polyoxyalkylene block via an oxygen atom,

[0083] the average molecular weight of each siloxane block is between about 400 and about 10,000, that of each polyoxyalkylene block being between about 300 and about 10,000,

[0084] the siloxane blocks represent from about 10% to about 95% of the weight of the block copolymer,

[0085] the average molecular weight of the block copolymer being at least 3000 and preferably between 5000 and 1,000,000 and even more particularly between 10,000 and 200,000.

[0086] R and R′ are preferably chosen from the group comprising alkyl radicals such as, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl and dodecyl radicals, aryl radicals such as, for example, phenyl and naphthyl, aralkyl radicals such as, for example, benzyl and phenylethyl, and tolyl, xylyl and cyclohexyl radicals.

[0087] Y is preferably —R″—, —RH—CO—, —R″—NHCO—, —R″—NH—CO—NH—R″′—NHCO, —R″—OCONH—R″′—NHCO—, where R″ is a divalent alkylene group such as, for example, ethylene, propylene or butylene and R″′ is a divalent alkylene group or a divalent arylene group such as —C₆H₄—, —C₆H₄—C₆H₄—, —C₆H₄—CH₂—C₆H₄—, —C₆H₄—C(CH₃)₂—C₆H₄—.

[0088] Even more preferably, Y represents a divalent alkylene radical, more particularly the —CH₂—CH₂—CH₂-radical or the C₄H₈radical.

[0089] The preparation of the block copolymers used in the context of the present invention is described in European patent application EP 0,492,657 A1, the teaching of which is included in the present description by way of reference.

[0090] The preferred linear polysiloxane/polyoxyalkylene block copolymers according to the invention are chosen from those of formula:

[0091] [C₄H₈O(C_nH_2nO)_b(C_mH_2mO)_d—C₄H₈—SiMe₂O(SiMe₂)_aSiMe₂]_c  (VI)

[0092] where Me represents methyl, n and m are integers ranging from 2 to 4, a is an integer greater than or equal to 4, preferably between 5 and 200, b and d are integers greater than or equal to 0, preferably between 4 and 200, b+d is greater than or equal to 4, preferably between 4 and 200, and c is a number greater than or equal to 4, preferably between 4 and 1000.

[0093] Among these copolymers, those having a repeating unit of formula:

[0094] [—(SiMe₂O)_xSiMe₂—C₄H₈O—(C₂H₄O)_y—(C₃H₆O)_z—C₄H₈—]  (VII)

[0095] where x is a number between 5 and 15 (limits included), y is a number between 15 and 30 (limits included) and z is a number between 20 and 40 (limits included), are used more particularly.

[0096] Among these polymers, those whose siloxane/polyoxyalkylene weight ratio is about 20 and whose polyoxyethylene/polyoxypropylene weight ratio is about 65/35 are used more particularly.

[0097] It is also possible to choose polymers whose repeating unit is of formula (VI) and whose siloxane/polyoxyalkylene weight ratio is about 75 and whose polyoxyethylene/polyoxypropylene weight ratio is about 50/50, polymers whose siloxane/polyoxyalkylene weight ratio is about 35 and whose polyoxyethylene/polyoxypropylene weight ratio is about 100/0, and polymers whose siloxane/polyoxyalkylene weight ratio is about 30 and whose polyoxyethylene/polyoxypropylene weight ratio is about 0/100.

[0098] According to a particular embodiment of the invention, the block copolymer is chosen from the following copolymers:

[0099] [[(CH₃)₂SiO]₄₁(CH₃)₂SiCH₂CH(CH₃)CH₂—O(C₂H₄O)₁₈—(C₃H₆O)₃₃CH₂CH(CH₃)CH₂]_16.1

[0100] [[(CH₃)₂SiO]₃₁(CH₃)₂SiCH₂CH(CH₃)CH₂—O(C₂H₄O)₂₀—(C₃H₆O)₂₉CH₂CH(CH₃)CH₂]_13.3

[0101] [[(CH₃)₂SiO]₉(CH₃)₂SiCH₂CH(CH₃)CH₂—O(C₂H₄O)₂₀—(C₃H₆O)₂₉CH₂CH(CH₃)CH₂]_26.3

[0102] [[(CH₃)₂SiO]₁₆(CH₃)₂SiCH₂CH(CH₃)CH₂—O(C₂H₄O)₁₈—(C₃H₆O)₂₀CH₂CH(CH₃)CH₂]_21.5

[0103] [[(CH₃)₂SiO]₉(CH₃)₂SiCH₂CH(CH₃)CH₂—O(C₂H₄O)₅—CH₂CH(CH₃)CH₂]_4.8

[0104] The linear block copolymer is preferably used in an amount of between 0.01 and 20% by weight relative to the total weight of the composition. More preferably, this amount is between 0.1 and 15% by weight and even more particularly between 0.5 and 10% by weight.

[0105] According to a preferred embodiment of the invention, the composition also contains a polymer, preferably a non-silicone anionic or amphoteric polymer, in solubilized form or in dispersed form.

[0106] The cosmetically or dermatologically acceptable medium preferably consists of water or a mixture of water and cosmetically acceptable solvents such as monoalcohols, polyalcohols, glycol ethers or fatty acid esters, which can be used alone or as a mixture.

[0107] Mention may be made more particularly of lower alcohols such as ethanol and ispropanol, polyalcohols such as diethylene glycol, glycol ethers, glycol alkyl ethers or diethylene glycol alkyl ethers.

[0108] The grafted silicone polymers according to the invention can be dissolved in the said cosmetically acceptable medium or used in the form of an aqueous dispersion of particles.

[0109] The composition of the invention can also contain at least one additive chosen from thickeners, fatty acid esters, fatty acid esters of glycerol, silicones, surfactants, fragrances, preserving agents, sunscreens, proteins, vitamins, plant, animal, mineral or synthetic oils or any other additive conventionally used in the cosmetic field.

[0110] These additives are present in the composition according to the invention in proportions which can range from 0 to 20% by weight relative to the total weight of the composition. The precise amount of each additive depends on its nature and is determined readily by those skilled in the art.

[0111] Needless to say, a person skilled in the art will take care to select the optional compound(s) to be added to the composition according to the invention 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 addition envisaged.

[0112] The compositions according to the invention can be in the form of a gel, a milk, a cream, a relatively thickened lotion or a mousse.

[0113] The compositions of the invention are used as rinse-out products or as leave-in products in particular to wash, care for, condition, maintain the style of or shape keratin substances such as the hair.

[0114] These compositions are more particularly styling products such as hairsetting lotions, blow-drying lotions, fixing compositions (lacquers) and styling compositions. The lotions can be packaged in various forms, in particular in vapourizers, pump-dispenser bottles or in aerosol containers in order to ensure application of the composition in vapourized form or in the form of a mousse. Such packaging forms are indicated, for example, when it is desired to obtain a spray, a lacquer or a mousse for fixing or treating the hair.

[0115] The compositions can also be shampoos, rinse-out or leave-in compositions, to be applied before or after shampooing, dyeing, bleaching, permanent-waving or straightening the hair.

[0116] When the composition according to the invention is packaged in aerosol form in order to obtain a lacquer or an aerosol mousse, it comprises at least one propellant which can be chosen from volatile hydrocarbons such as n-butane, propane, isobutane, pentane, a chloro and/or fluoro hydrocarbon, and mixtures thereof. Carbon dioxide, nitrous oxide, dimethyl ether, nitrogen or air, which is compressed, and mixtures thereof, can also be used as propellant.

[0117] Another subject of the invention is a process for treating keratin substances such as the hair, which consists in applying a composition as defined above to the hair and then optionally in rinsing with water.

[0118] The invention will now be illustrated more fully with the aid of the examples which follow, which should not be considered as limiting it to the embodiments described. In the text which follows, AM means active material.

[0119] A haircare spray packaged in a pump-dispenser bottle, of the following composition, was prepared:

[0120] A haircare mousse of the following composition was prepared:

[0121] A styling gel of the following composition was prepared:

[0122] a) 60% by weight of tert-butyl acrylate;

[0123] b) 20% by weight of acrylic acid;

[0124] c) 20% by weight of silicone macromer of formula:

[0125] with n being a number chosen such that the number-average molecular weight of the polymer is approximately 9000-12,000; the weight percentages being calculated relative to the total weight of the monomers,

[0126] A shampoo of the following composition was prepared:

[0127] The ph is adjusted to 5.8 by addition of hydrochloric acid.

[0128] A rinse-out conditioner of the following composition was prepared:

[0129] The pH is adjusted to 5 by addition of 5 hydrochloric acid.

[0130] I Fixing Power

[0131] The fixing power obtained by the three formulations A, B and C below were studied and compared:

[0132] Procedure

[0133] A test for measurement of the strength of the bonds formed between hairs by a hair lacquer is carried out according to the principles of the method described in the article by R. Randall Wickett, John A. Sramek and Cynthia M. Trobaugh in J. Soc. Cosmet. Chem. 43, 169-178 (May/June 1992).

[0134] A single strand of hair is taken for each formulation tested. The strand of hair is made into a simple loop having a diameter of approximately 2 cm, using a cylindrical support. The hair thus looped is soaked in the formulation and is left to dry under a conditioned atmosphere (20° C. and 50% humidity). The loop fixed with formulation A, B or C is cut. 2 half-strands of hair linked together by a fixing point are thus obtained.

[0135] The ends, located on either side of the fixing point, are fixed in each of the two jaws of an Instron® type machine which measures the tensile force in Newtons exerted on the half-strands of hair.

[0136] The average force (average of ten tests) F_A, F_Band F_C(specific to composition A, B or C) required to break the fixing point joining the two half-strands of hair and formed by the formulation A, B or C is measured.

[0137] The enhancement afforded by the combination of the grafted silicone polymer P₁and the copolymer P₂relative to the polymer P₁(composition A) used alone or relative to the combination of P₁and a polyoxyalkylenated silicone (composition C) is determined by calculating the relative variation in the breaking force measured, expressed as a percentage, according to the following formula:

[0138] (F_B−F_A/F_A)×100 or (F_B−F_C/F_C)×100

[0139] The results are given in the table below:

[0140] The fixing power of the composition according to the invention is markedly superior to that of the compositions of the prior art.