FR2735690A1 - Cosmetic compsns. contg. stabilised polymeric dispersion in liq. fatty medium - Google Patents

Abstract

Cosmetic compsns. consisting of fatty and powdered components comprise particles of surface-stabilised polymer dispersed in a fatty liq. medium. The liq. fatty medium is pref. chosen from non aq. liq. compsns. with an overall solubility parameter in the HANSEN interval of solubility of <17 (MPa)<1/2>; and/or monoalcohols with an overall solubility parameter in the HANSEN interval of solubility of <20 (MPa)<1/2>. The liq. fatty medium is selected from wax, oils, rubber and/or fatty greasy components which are silicon-base or of mineral, animal, plant and synthetic origin, fatty liquids include e.g. paraffin oil, vaseline or soya oil. The polymer may be a radical polymer, a polycondensate and/or a naturally occuring polymer. The polymer particles are surface stabilised by a sequenced polymer, a graft polymer and/or a statistical polymer.

Description

The present invention relates to a cosmetic, dermatological, pharmaceutical or hygienic composition, in particular for caring for and / or making up the skin, in the form of a cast product and comprising a dispersion of particles of crosslinked polymer, in a liquid fatty substance. as well as to the use of such a dispersion in such a composition.

Cosmetic or dermatological compositions which can be applied to the skin or the lips as a make-up or care product, such as bases or lipsticks or foundations for example, generally contain fatty substances such as waxes and oils. , pigments and / or fillers and, optionally, additives. It is known that the greater the quantity of waxes present in the composition, the more the latter has a firm consistency, which allows its use in the form of a stick.

Compositions are also known in the form of a flexible paste, applicable using a brush, for example. These compositions generally contain a small amount of waxes, and fatty substances of the pasty and / or oily type. The fatty substances of pasty type are generally present in a large amount, so as to obtain a composition of adequate consistency and viscosity while allowing application.

However, it has been observed that these compositions exhibited a certain ability to migrate, that is to say tended to spread inside fine lines of the skin, in particular those surrounding the lips, creating an unsightly effect, this migration being partly due to the presence of oily or pasty fatty substances.

There therefore remains a need for a composition which migrates shortly after its application to the skin and over time.

The Applicant has observed that, quite surprisingly, the use of a dispersion according to the invention in a cosmetic, dermatological, pharmaceutical or hygienic composition could make it possible to obtain a film of very good staying power, which migrates little to the surface. over time, while being very comfortable to wear.

An object of the present invention is therefore a composition in the form of a cast product and comprising at least one wax, characterized in that it further comprises a dispersion of particles of crosslinked polymer and stabilized at the surface, in a cosmetically, dermatologically, hygienically or pharmaceutically acceptable liquid fatty substance.

Another subject of the invention is the use, in a composition in the form of a cast product and comprising at least one wax, of a dispersion of particles of crosslinked polymer and stabilized at the surface in a liquid fatty substance cosmetically, dermatologically, pharmaceutically or hygienically acceptable, in particular with the aim of reducing the migration of the constituents of said composition into the fine lines of the skin, and / or of improving their staying power.

One of the advantages of using a dispersion of particles according to the invention is that the particles remain in the state of elementary particles, without forming agglomerates, in the liquid fatty substance, which would not be the case with mineral particles of nanometric size.

Another advantage of such a dispersion is that it is possible to calibrate the size of the polymer particles at will, and to modulate their size polydispersity during the synthesis. This is not possible when pigments are used in particulate form, their constitution not making it possible to modulate the average size of the particles, nor their hardness. It is thus possible in particular to obtain polymer particles of very small size, in particular nanometric, particles which will be invisible when they are in the composition and / or when they are applied to the skin.

The dispersions according to the invention therefore consist of generally spherical particles of at least one crosslinked polymer which is surface stabilized, in a cosmetically and / or dermatologically acceptable liquid fatty substance.

These dispersions can in particular be in the form of nanoparticles of polymers in stable dispersion in said liquid fatty substance. The nanoparticles are preferably between 5 and 600 nm in size, since above about 600 nm the particle dispersions become much less stable.

The polymers used in the present application can be of any kind.

It is thus possible to use radical polymers, polycondensates, or even polymers of natural origin. The polymer can be chosen by a person skilled in the art as a function of its properties, depending on the subsequent application desired for the composition.

Among the polymers that can be envisaged, there may be mentioned homopolymers or free-radical, acrylic or crosslinked vinyl copolymers, such as polymethyl methacrylate, polystyrene or tert-butyl polyacrylate.

It is possible to add to the dispersion of polymers, a plasticizer so as to lower the Tg of the polymers used. The plasticizer can be chosen from the plasticizers usually used in the field of application and in particular from the compounds capable of being solvents for the polymer.

The polymer used is crosslinked so as to prevent its film formation when it is deposited on the skin. The crosslinking agent can be chosen from any crosslinking agent known in radical polymerization, in particular di- or multifunctional crosslinking agents such as ethylene glycol dimethacrylate or divinylbenzene.

The crosslinking can be carried out by any means known to those skilled in the art.

The liquid fatty substance in which the polymer particles are dispersed may consist of any cosmetic or dermatologically acceptable oil, alone or as a mixture, in particular chosen from natural or synthetic, carbon-based, hydrocarbon-based, fluorinated and / or silicone oils, optionally branched. , alone or as a mixture insofar as they form a homogeneous and stable mixture and where they are compatible with the intended use.

Mention may thus be made of hydrocarbon-based oils such as paraffin or petrolatum oil; perhydrosqualene; Arara oil; Sweet almond, calophyllum, palm, castor, avocado, jojoba, olive or grain germ oil; esters of lanolic acid, oleic acid, lauric acid, stearic acid; silicone oils such as PDMS, optionally phenylated such as phenyltrimethicones. It is also possible to use volatile oils, such as cyclotetrad imethylsiloxane, cyclopentad imethylsiloxane, cyclohexadimethylsiloxane, methylhexyldimethylsiloxane or isoparaffins.

The choice of the liquid fatty substance can be made by a person skilled in the art depending on the nature of the monomers, of the polymer and / or of the stabilizer, as is indicated below.

In general, the dispersion according to the invention can be prepared as follows, given by way of example.

The polymerization can be carried out in dispersion, that is to say by precipitation of the polymer during formation, with protection of the particles formed with a stabilizer.

A mixture is therefore prepared comprising the initial monomers as well as a radical initiator. This mixture is dissolved in a solvent called, in the remainder of the present description, “synthesis solvent”.

When the liquid fatty substance is a non-volatile oil, the polymerization can be carried out in an apolar organic solvent (synthesis solvent) then add the non-volatile oil (which must be miscible with said synthesis solvent) and selectively distill the solvent from synthesis.

A synthesis solvent is therefore chosen such that the initial monomers and the radical initiator are soluble therein, and the polymer particles obtained are insoluble therein so that they precipitate therein during their formation.

In particular, the synthesis solvent can be chosen from alkanes such as heptane or cyclohexane.

When the liquid fatty substance chosen is a volatile oil, the polymerization can be carried out directly in said oil which therefore also acts as a synthesis solvent. The monomers must also be soluble therein, as well as the radical initiator, and the polymer obtained must be insoluble therein.

The monomers are preferably present in the synthesis solvent, before polymerization, in an amount of 5-20% by weight. All of the monomers can be present in the solvent before the start of the reaction, or part of the monomers can be added as the polymerization reaction progresses.

The radical initiator can in particular be azo-bis-isobutyronitrile or tert-butylperoxy-2-ethyl hexanoate.

The polymer particles are stabilized at the surface, when they form during the polymerization, thanks to a stabilizer which can be a surfactant, a block polymer, a graft polymer, and / or a random polymer, alone or as a mixture.

Stabilization can be carried out by any known means, and in particular by direct addition of the surfactant, block polymer, graft polymer and / or random polymer, during the polymerization.

The stabilizer is preferably also present in the mixture before polymerization. However, it is also possible to add it continuously, in particular when the monomers are also added continuously.

2-30% by weight of stabilizer can be used with respect to the initial mixture of monomers, and preferably 5-20% by weight.

When a grafted and / or sequenced polymer is used as stabilizer, the synthesis solvent is chosen such that at least part of the grafts or blocks of said polymer-stabilizer is soluble in said solvent, the other part grafts or sequences not being soluble therein.

The insoluble part of said polymer-stabilizer then adsorbs to the surface of the polymer particles formed during the polymerization.

The polymer-stabilizer used during the polymerization must be soluble, or dispersible, in the synthesis solvent and in the final liquid fatty substance.

In addition, a stabilizer is preferably chosen, the insoluble blocks or grafts of which have a certain affinity for the polymer formed during the polymerization.

Among the grafted polymers, mention may be made of silicone polymers grafted with a hydrocarbon chain; hydrocarbon polymers grafted with a silicone chain; graft copolymers having an insoluble backbone of polyacrylic type with soluble grafts of polyhydroxystearic acid type. Mention may also be made of graft copolymers of acrylic / silicone type which can be used in particular when the nonaqueous medium is silicone. Such copolymers are in particular sold by 3M or by Shin Etsu.

The block polymers are in the form of a series of sequences which may be of the AB, ABA or (AB) n type. Mention may in particular be made of block copolymers, in particular of the 'diblock' or 'triblock' type of the polystyrene / polyisoprene, polystyrene / polybutadiene, polystyrene / copoly (ethylenepropylene) or even polystyrene / copoly (ethylene-butylene) type, such as those sold under the name 'KRATON' by Shell Chemical Co. or the polymers sold under the name 'LUVITOL' by BASF.

When a random polymer is used as stabilizer, it is chosen so that it has a sufficient quantity of groups making it soluble in the synthesis solvent envisaged.

It is thus possible to use copolymers of acrylates or methacrylates of C1-C4 alcohols, and of acrylates or methacrylates of C8-C30 alcohols. Mention may in particular be made of the stearyl methacrylate / methyl methacrylate copolymer.

When the synthesis solvent is apolar, it is preferable to choose, as stabilizer, a polymer providing the most complete possible coverage of the particles, several polymer-stabilizer chains then being adsorbed on a polymer particle obtained by polymerization.

In this case, it is then preferred to use, as stabilizer, either a graft polymer or a block polymer, so as to have better interfacial activity.

In fact, the sequences or grafts which are insoluble in the synthetic solvent provide a more voluminous coverage at the surface of the particles.

The composition according to the invention further comprises at least one wax and may comprise additional fatty substances and / or pulverulent compounds customary in the fields considered.

Among the waxes which may be present in the composition according to the invention, mention may be made of hydrocarbon waxes such as beeswax; wax
Carnauba, Candellila, Ourrury, Japan, waxes of cork fibers or sugar cane; paraffin waxes, lignite waxes; microcrystalline waxes; lanolin wax; monta n wax; ozokerites; polyethylene waxes; waxes obtained by Fischer-Tropsch synthesis; hydrogenated oils, fatty esters and glycerides which are concrete at 25 ° C. Silicone waxes can also be used, among which there may be mentioned the alkyls, alkoxies and / or esters of polymethylsiloxane. The waxes can be present in an amount of 5 -50% by weight in the composition.

The composition can also comprise other fatty substances such as oils, gums and / or pasty fatty substances, of plant, animal, mineral or synthetic origin, or even silicone. Among the oils which may be present in the composition according to the invention, mention may be made of hydrocarbon-based oils such as paraffin or petrolatum oil; perhydrosqualene; arara oil;
Sweet almond, calophyllum, palm, castor, avocado, jojoba, olive or grain germ oil; esters of lanolic acid, oleic acid, lauric acid, stearic acid; alcohols such as oleic alcohol, linoleic or linolenic alcohol, isostearic alcohol or octyl dodecanol. Mention may also be made of silicone oils such as PDMS, optionally phenylated such as phenyltrimethicones. One can also use volatile oils, such as cyclotetradimethylsiloxane, cyclopentadimethylsiloxane, cyclohexadimethylsiloxane, methylhexyldimethylsiloxane or isoparylsiloxines.

The composition can also comprise pulverulent compounds, for example in an amount of 0-60% by weight, preferably 2-15% by weight, and which can be chosen from pigments and / or nacres and / or fillers usually used. in cosmetic compositions.

The pigments can be white or colored, mineral and / or organic. Mention may be made, among inorganic pigments, of titanium, zirconium or cerium dioxides, as well as oxides of zinc, iron or chromium, ferric blue. Among the organic pigments, mention may be made of carbon black, and barium, strontium, calcium and aluminum lakes.

The nacres can be chosen from mica coated with titanium oxide, iron oxide, natural pigment or bismuth oxychloride as well as colored titanium mica.

The fillers can be mineral or synthetic, lamellar or non-lamellar.

Mention may be made of talc, mica, silica, kaolin, nylon and polyethylene powders, Teflon, starch, micatitanium, natural mother-of-pearl, boron nitride, hollow microspheres such as Expancel. (Nobel Industrie), the polytrap (Dow
Corning) and silicone resin microbeads (Toshiba Tospearls, for example).

The composition can also comprise any additive usually used in the cosmetics field, such as antioxidants, perfumes, essential oils, preservatives, cosmetic active ingredients, moisturizers, vitamins, essential fatty acids, sphingoceryls, filters. sunscreen, surfactants, liposoluble polymers such as polyalkylenes, in particular polybutene, polyacrylates and silicone polymers compatible with fatty substances.

Of course, a person skilled in the art will take care to choose this or these optional additional compounds, and / or their quantity, in such a way that the advantageous properties of the composition according to the invention are not, or substantially not, altered by the addition considered.

The compositions according to the invention can be in the form of a stick or stick, or in the form of a flexible paste, with a dynamic viscosity at 25 ° C. of the order of 3-30 Pa.s.

They are in the form of a cast product, prepared in the usual manner by a person skilled in the art, or else in the form of a dish which can be used by direct contact or with a sponge.

In particular, they can be in the form of a cast foundation, a cast blush or eye shadow, a lipstick or a lip care base, or a lipstick. care balm.

The invention is illustrated in more detail in the following examples.

Examples 1 to 4 describe the dispersion preparation according to the invention, and Examples 5 to 6 describe compositions according to the invention.

Example 1
360 g of n-heptane and 15 g of block stabilizing polymer of polystyrene / copoly (ethylene-propylene) diblock copolymer type sold under the name KRATON G1701 (Shell) are mixed.

The mixture is heated for at least 3 h, at about 60 ° C to obtain a dispersed solution.

At 25 ° C., 19 g of methyl methacrylate, 1 g of ethylene glycol dimethacrylate, 0.4 g of tert-butylperoxy-2-ethylhexanoate (Trigonox 21S from Akzo) and 5 g of heptane are added to the mixture.

The mixture is heated to 75 ° C, under nitrogen, for at least 3 hours.

Then added at 75 ° C and over 1.5 hours, a mixture of 76 g of methyl methacrylate, 4 g of ethylene glycol dimethacrylate, 1.6 g of tert-butylperoxy-2-ethylhexanoate (Trigonox 21S from Akzo) and 80 g of heptane.

At the end of the addition, heat at 85 ° C for 4 hours, add 1 g of Trigonox dissolved in 5 g of heptane, and further heat at 85 ° C for 7 hours.

A stable dispersion of milky appearance is obtained, with a solids content of 18.6% by weight.

The measurement of the particle size, carried out by quasi-elastic light scattering with a Coulter N4 SD, gives the following results: mean particle size nm nm
polydispersity less than 0.1.

50 g of the above heptane dispersion are mixed with 28.5 g of non-volatile paraffin oil. The heptane is selectively evaporated using a rotary evaporator.

This gives a stable dispersion of milky appearance, having a solids content of 25% by weight, of polymethyl methacrylate crosslinked with ethylene glycol dimethacrylate, in a paraffin oil.

Example 2
A dispersion of polymethyl methacrylate crosslinked with ethylene glycol dimethacrylate is prepared in a branched and volatile paraffin oil (ISOPAR L from Exxon), according to the method of Example 1, replacing heptane with said paraffin oil. ISOPAR L.

A stable dispersion is thus obtained, having a solids content of 19% by weight and an average particle size of 159 nm (polydispersity: 0.05).

Example 3
20 g of the dispersion in ISOPAR above is mixed with 16.2 g of cyclotetradimethylsiloxane (volatile silicone oil).

A stable dispersion of milky appearance is then obtained, consisting of 3.8 g of polymethyl methacrylate crosslinked with ethylene glycol dimethacrylate, 16.2 g of volatile paraffin oil and 16.2 g of silicone oil. volatile.

Example 4
20 g of the dispersion in ISOPAR of Example 2 are mixed with 16.2 g of C12-C15 alcohol benzoate (FINSOLV TN from Witco).

A stable dispersion of milky appearance is then obtained, consisting of 3.8 g of polymethyl methacrylate crosslinked with ethylene glycol dimethacrylate, 16.2 g of volatile paraffin oil and 16.2 g of non-volatile ester. .

Example 5
A lipstick is prepared in the form of a soft paste having the following composition:
waxes (bees and Carnauba) 5g
oils 20 g
acetylated lanolin 20 g
lanolin 30 g
loads 10 9
pigments 10 9
dispersion according to example 1 5g
The composition is prepared by heating the various ingredients to 95-100 "C, mixing so as to obtain a perfectly homogeneous mixture.

After cooling, a lipstick is obtained which is easy to apply and which makes it possible to obtain a film which is pleasant to wear.

It can be seen that the film does not migrate into the fine lines of the skin, even after having been worn for several hours.

Example 6
A lipstick is prepared in the form of a stick, having the following composition:
castor oil 15 g
jojoba oil 13 g
hydrogenated coconut oil 7g
isopropyl lanolate 25 g
Carnauba wax 10 g
polyethylene wax 10 g
pigments and fillers 15 g
dispersion of example 1 5g
The stick is prepared as follows: the fatty phase is heated to a temperature of about 100 "C, the fillers and pigments are added, then the whole is mixed using a Moritz turbine at high speed. speed of 3000 rpm Said mixture can then be poured into suitable molds.

The composition obtained is easy and pleasant to apply. It can be seen that the film does not migrate into the fine lines of the skin, even after having been worn for several hours.

Claims (28)

1. Composition in the form of a cast product and comprising at least one wax, characterized in that it further comprises a dispersion of particles of crosslinked polymer and stabilized at the surface, in a cosmetically, dermatologically liguid fatty substance , hygienically or pharmaceutically acceptable. 2. The composition of claim 1, wherein the particles are spherical and have an average size of 5 to 600 nm. 3. Composition according to one of the preceding claims, in which the crosslinked and surface stabilized polymer is chosen from free-radical polymers, polycondensates, and / or polymers of natural origin. 4. Composition according to one of the preceding claims, in which the crosslinked and stabilized polymer is chosen from crosslinked acrylic or vinyl homopolymers or copolymers, such as polymethyl methacrylate, polystyrene or tert-butyl polyacrylate. 5. Composition according to one of the preceding claims, in which the polymer is crosslinked with a crosslinking agent chosen from di- or multifunctional crosslinking agents such as ethylene glycol dimethacrylate or divinylbenzene. 6. Composition according to one of the preceding claims, in which the polymer is stabilized by a stabilizer chosen from surfactants, block polymers, graft polymers, random polymers, and mixtures thereof. 7. Composition according to claim 6, in which the block stabilizing polymer is chosen from block copolymers, in particular of the 'diblock' or 'triblock' type of the polystyrene / polyisoprene, polystyrene / polybutadiene, polystyrenelcopoly (ethylene-propylene) or also polystyrene / copoly (ethylene-butylene), such as those sold under the name 'KRATON' by Shell Chemical Co. or the polymers sold under the name 'LUVITOL' by BASF. 8. Composition according to Claim 6, in which the grafted stabilizing polymer is chosen from silicone polymers grafted with a hydrocarbon chain; hydrocarbon polymers grafted with a silicone chain; graft copolymers having a polyacrylic type backbone with polyhydroxystearic acid type grafts; acrylic / silicone type graft copolymers. 9. The composition of claim 6, wherein the random stabilizing polymer is chosen from copolymers of acrylates or methacrylates of C1-C4 alcohols, and acrylates or methacrylates of C8-C30 alcohols, such as stearyl methacrylate / methyl methacrylate copolymer. 10. Composition according to one of claims 6 to 9, in which the stabilizer is present in an amount of 2-30% by weight of stabilizer relative to the initial mixture of monomers serving to form the polymer to be stabilized, and preferably 520%. in weight. 11. Composition according to one of the preceding claims, in which the liquid fatty substance is chosen from natural or synthetic, carbon-based, hydrocarbon-based, fluorinated and / or silicone oils, optionally branched, alone or as a mixture. 12. Composition according to one of the preceding claims, in which the liquid fatty substance is chosen from hydrocarbon-based oils such as paraffin or petrolatum oil; perhydrosqualene; Arara oil; Sweet almond, calophyllum, palm, castor, avocado, jojoba, olive or grain germ oil; esters of lanolic acid, oleic acid, lauric acid, stearic acid; silicone oils such as PDMS, optionally phenylated such as phenyltrimethicones; volatile oils, such as cyclote trad imethylsiloxane, cyclopentad imethylsiloxane, cyclohexadimethylsiloxane, methylhexyldimethylsiloxane or isoparaffins; and their mixtures. 13. Composition according to one of the preceding claims, in which the wax is chosen from hydrocarbon waxes such as beeswax; wax Carnauba, Candellila, Ourrury, Japan, waxes of cork fibers or sugar cane; paraffin waxes, lignite waxes; microcrystalline waxes; lanolin wax; monta n wax; ozokerites; polyethylene waxes; waxes obtained by Fischer-Tropsch synthesis; hydrogenated oils, fatty esters and concrete glycerides at 25 ° C., silicone waxes such as alkyls, alkoxies and / or polymethylsiloxane esters. 14. Composition according to one of the preceding claims, in which the wax is present in an amount of 5-50% by weight. 15. Composition according to one of the preceding claims, further comprising additional fatty substances chosen from oils, gums and / or pasty fatty substances, of plant, animal, mineral or synthetic origin, or even silicone. 16. Composition according to one of the preceding claims, further comprising pulverulent compounds chosen from pigments, nacres and / or fillers. 17. Composition according to one of the preceding claims, which is in the form of a stick or stick; in the form of a flexible paste, with a dynamic viscosity at 25 "C of the order of 3-30 Pa.s; in the form of a cup. 18. Composition according to one of the preceding claims, which is in the form of a product for caring for and / or making up the skin, such as a cast foundation, a cast blush or eye shadow, a rouge. lip care or lip care primer, or care balm. 19. Use, in a composition in the form of a cast product and comprising at least one wax, of a dispersion of particles of crosslinked polymer and stabilized at the surface in a cosmetically, dermatologically, pharmaceutically or hygienically acceptable liquid fatty substance. 20. Use according to claim 19, for the purpose of reducing the migration of the constituents of the composition into the fine lines of the skin. 21. Use according to one of claims 19 to 20, in order to improve the hold of the composition. 22. Use according to one of claims 19 to 21, in which the crosslinked and surface stabilized polymer is chosen from radical polymers, polycondensates, and / or polymers of natural origin. 23. Use according to one of claims 19 to 22, wherein the crosslinked and stabilized polymer is chosen from crosslinked acrylic or vinyl homopolymers or copolymers, such as polymethyl methacrylate, polystyrene or tert-butyl polyacrylate. 24. Use according to one of claims 19 to 23, in which the polymer is stabilized by a stabilizer chosen from surfactants, block polymers, graft polymers, random polymers, and mixtures thereof, and in particular from block copolymers, in particular of the 'diblock' or 'triblock' type of the polystyrene / polyisoprene, polystyrenepolybutadiene, polystyrene / copoly (ethylenepropylene) or polystyrene / copoly (ethylene-butylene) type, such as those sold under the name 'KRATON 'by Shell Chemical Co. or the polymers sold under the name' LUVITOL 'by BASF; silicone polymers grafted with a hydrocarbon chain; hydrocarbon polymers grafted with a silicone chain; graft copolymers having a polyacrylic type backbone with polyhydroxystearic acid type grafts; acrylic / silicone type graft copolymers; copolymers of acrylates or methacrylates of C1-C4 alcohols, and acrylates or methacrylates of C8-C30 alcohols, such as stearyl methacrylate / methyl methacrylate copolymer. 25. Use according to one of claims 19 to 24, in which the liquid fatty substance is chosen from natural or synthetic, carbon-based, hydrocarbon-based, fluorinated and / or silicone oils, optionally branched, alone or as a mixture. 26. Use according to one of claims 19 to 25 in a composition in the form of a stick or stick, of a flexible paste of dynamic viscosity at 25 "C of the order of 3-30 Pa.s. , or a cup. 27. Use according to one of claims 19 to 26 in a composition in the form of a product for caring for and / or making up the skin, such as a cast foundation, a blush or blush. sunken eyelids, lipstick or lip care primer, or care balm. 28. Cosmetic or hygienic treatment process consisting in applying to the skin a composition in the form of a cast product, comprising at least one wax and a dispersion of particles of crosslinked polymer and stabilized at the surface in a liquid fatty substance cosmetically, dermatologically, pharmaceutically or hygienically acceptable.