The present invention relates to a photocrosslinkable cosmetic composition, particularly for nail and/or false nail makeup and/or care.

More particularly, the present invention relates to a photocrosslinkable cosmetic finishing composition.

The present invention also relates to a nail and/or false nail makeup and/or care method using said composition.

Nail varnish compositions may be used as a base for the varnish (or base-coat), as a nail makeup product, or as a finishing composition (or top-coat) to be applied on the nail makeup product, or as a cosmetic nail care product. These compositions may be applied onto natural nails as well as onto false nails.

In the field of nail varnishes, liquid cosmetic compositions are known, which, after application on the nail and under the effect of light radiation, undergo in situ polymerization and/or crosslinking reactions, resulting in generally crosslinked polymeric networks. Such photopolymerizable and/or photocrosslinkable compositions are described for example in CA 1 306 954, US 5 456 905, US 7 375 144 and FR 2 823 105.

A drawback of these compositions lies in the difficulty removing same during makeup removal.

Furthermore, the stability over time of these photocrosslinkable compositions, both in terms of chipping resistance and gloss, needs to be enhanced further.

Another drawback of these compositions lies in the toxicity of the unsaturated monomers used. Indeed, these highly reactive low molecular weight molecules diffuse readily in the underlying and adjacent substrates where they react with biological molecules.

The aim of the present invention is also to provide a novel photocrosslinkable composition which is easy to use and remove.

The aim of the present invention is also to provide a novel photocrosslinkable compositions exhibiting an enhanced stability over time, in terms of chipping resistance and gloss.

The aim of the present invention is also to provide a photocrosslinkable composition suitable for solving the toxicity problem in respect of the photocrosslinkable cosmetic compositions according to the prior art.

Another aim of the invention is to obtain photocrosslinkable compositions suitable for providing coats having the following properties: stability over time (with a mild etching or without any etching of the nail or false nail before applying the composition), easy makeup removal, high cosmeticity, outstanding makeup result (homogeneous deposition, easy to apply, comfortable to wear) and/or high gloss.

The present invention relates to a photocrosslinkable cosmetic composition, comprising in a physiologically acceptable medium:

- at least one photocrosslinkable urethane (meth)acrylate compound P1 comprising a polyether chain, said compound having a molar mass greater than or equal to 1000 g/mol,

at least one film-forming polymer P2,

- at least one photoinitiator, and

- at least one volatile solvent chosen from acetone, ethyl acetate, and propyl acetate, said solvent being preferably present in said composition at a content greater than or equal to 20%, preferentially greater than or equal to 30%, by weight in relation to the total weight of said composition, wherein the proportion of (meth)acrylate monomer is preferably less than or equal to 10% by weight in relation to the total weight of said composition, and

wherein the weight ratio between P1 and P2 is less than or equal 2.0.

The cosmetic compositions according to the invention comprise a physiologically acceptable medium.

The term "physiologically acceptable medium" refers to a medium that is particularly suitable for the application of a composition of the invention onto keratin matter.

The physiologically acceptable medium is generally suitable for the nature of the support to which the composition should be applied, and also for the way in which the composition is to be packaged.

The term "photocrosslinkable compound" refers to an organic compound suitable for crosslinking under the action of a light ray, resulting in a crosslinked polymer network.

Urethane (meth)acrylate compound

The composition according to the invention comprises at least one photocrosslinkable compound, referred to as P1 , which is a urethane (meth)acrylate compound and comprises a polyether chain.

The term "(meth)acrylate monomer" refers to a compound comprising a single (meth)acrylate function according to the formula H ₂ C=C(R)-C(0)-0-, where R = H or CH ₃ .

According to one embodiment, the photocrosslinkable composition according to the invention comprises a reduced proportion of (meth)acrylate monomers, i.e. less than 10% by weight in relation to the total weight of said composition. Preferably, this proportion is less than or equal to 5%, preferentially less than or equal to 1 % by weight. Advantageously, the composition according to the invention is completely free from (meth)acrylate monomer.

The term "urethane (meth)acrylate compound" refers to any compound comprising at least one urethane function -0-C(0)-NH-, and at least one (meth)acrylate function according to the formula H ₂ C=C(R)-C(0)-0-, where R = H or CH ₃ .

The "urethane" function is also referred to as a "carbamate" function.

According to one embodiment, the photocrosslinkable compound P1 is chosen from the group consisting of urethane poly(meth)acrylate compounds, advantageously in the group consisting of urethane di(meth)acrylate compounds, preferably in the group consisting of urethane dimethacrylate compounds.

According to the present invention, the term "poly(meth)acrylate compound" refers to a (meth)acrylate compound comprising a plurality of (meth)acrylate functions.

In this way, the term "poly(meth)acrylate compound" may refer to a compound comprising at least two methacrylate functions, or at least two acrylate functions, or at least one methacrylate function and at least one acrylate function.

Preferably, P1 is a urethane methacrylate compound.

Advantageously, the mean number of (meth)acrylate functions borne by the photocrosslinkable compounds P1 intended to form, after crosslinking, a crosslinked polymeric network, is greater than 1 . Indeed, a polymerizable system consisting of molecules each bearing a single (meth)acrylate function forms, after reacting all of said functions, a linear or branched, and not crosslinked, chain macromolecular system. Only the presence of a certain fraction of molecules bearing at least two (meth)acrylate functions and thus acting as a crosslinking agent is suitable for obtaining a crosslinked polymeric system.

In the implementation of the present invention, the mean number of (meth)acrylate functions per molecule of compound P1 is preferably greater than or equal to 2, advantageously ranging from 2 to 6, preferably from 2 to 4.

Preferentially, P1 is a urethane dimethacrylate compound.

The term "urethane dimethacrylate compound" refers to any compound comprising at least one urethane function -0-C(0)-NH-, and two methacrylate functions according to the formula H ₂ C=C(CH ₃ )-C(0)-0-. Polyether chain

The term "polyether chain" refers to a C ₁ -C ₁₀₀ divalent hydrocarbon radical, interspersed with at least two oxygen atoms.

Preferably, the polyether chain of the compound P1 has a molar mass less than or equal to 1000 g/mol.

Preferentially, the polyether chain generally comprises less than 50 carbon atoms, preferably less than 45 carbon atoms.

According to one embodiment, the polyether chain of the photocrosslinkable compound P2 is of formula -[C _n H ₂ nO] _m -, wherein n is an integer ranging from 1 to 6, preferably equal to 2 or 3, and m is an integer ranging from 2 to 50.

It may thus consist for example of a polyoxymethylene chain according to the formula -[CH ₂ 0] _m -, a poly(ethyleneglycol) chain according to the formula -[CH ₂ CH ₂ 0] _m -, a poly(propyleneglycol) chain according to the formula -[CH ₂ CH(CH ₃ )0] _m - or a polytetramethyleneglycol chain according to the formula -[(CH ₂ ) ₄ 0] _m -.

According to one preferred embodiment of this alternative embodiment, the polyether chain is such that n = 2 and m ranges from 2 to 20, preferably from 5 to 20.

According to another embodiment, the polyether chain of the photocrosslinkable compound P1 is of formula -[PhO] _m -, wherein Ph refers to a phenylene divalent radical, optionally substituted with one or a plurality of C C ₆ alkyls and/or halogen atoms, and m is an integer ranging from 2 to 50.

It may thus consist for example of a polyphenylether chain according to the formula -[C ₆ H ₄ 0] _m - or a poly(p-dimethylphenyl)ether chain according to the formula -[(C ₆ H ₂ )(CH ₃ ) ₂ 0] _m -.

Compound P1

According to one embodiment, the compound P1 is of formula (I):

wherein -A- represents a C ₁ -C ₁₀₀ divalent hydrocarbon radical, optionally substituted with alkyl groups, said radical being interspersed with at least one urethane function -0-C(0)-NH-, at least one polyether chain as defined above, and optionally with heteroatoms, such as oxygen, nitrogen, sulfur atoms, or saturated, aromatic or heteroaromatic cyclic divalent groups, such as cycloalkylene, arylene or heteroarylene groups. Within the scope of the present invention, the heteroatoms include oxygen, nitrogen and sulfur atoms.

According to the present invention, the "alkyl" groups represent straight or branched chain saturated hydrocarbon radicals, comprising from 1 to 10 carbon atoms, preferably from 1 to 6 carbon atoms. Mention may particularly be made, when they are linear, of methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, nonyl and decyl radicals. Mention may particularly be made, when they are branched or substituted with one or a plurality of alkyl radicals, of isopropyl, tert-butyl, 2-ethylhexyl, 2-methylbutyl, 2-methylpentyl, 1 - methylpentyl and 3-methylheptyl radicals.

The "cycloalkene" radical is a non-aromatic saturated or partially unsaturated mono-, bi- or tri- cyclic divalent hydrocarbon radical, comprising from 3 to 20 carbon atoms, and preferably from 3 to 10 carbon atoms, such as in particular cyclopropylene, cyclopentylene, cyclohexylene or adamantylene, optionally substituted with alkyl groups, and the corresponding rings containing one or a plurality of unsaturations.

In this way, within the scope of the present invention, the term "cycloalkylene" also covers "heterocycloalkylene" radicals denoting non-aromatic saturated or partially unsaturated mono- or bicyclic divalent radicals, of 3 to 8 carbon atoms, comprising one or a plurality of heteroatoms chosen from N, O or S.

The term "arylene" refers to a mono or bicyclic aromatic divalent hydrocarbon radical, comprising from 6 to 30, preferably from 6 to 10, carbon atoms. Of the arylene radicals, mention may particularly be made of the phenylene or naphthylene radical, more particularly substituted with at least one halogen atom.

If the arylene radical comprises at least one heteroatom, the term "heteroarylene" radical is used. In this way, the term "heteroarylene" refers to an aromatic divalent radical comprising one or a plurality of heteroatoms chosen from nitrogen, oxygen or sulfur, comprising from 5 to 30, and preferably from 5 to 10, carbon atoms. Of the heteroarylene radicals, mention may be made of pyrazinylene, thienylene, oxazolylene, furazanylene, pyrrolylene, 1 ,2,4-thiadiazolylene, naphthyridinylene, pyridazinylene, quinoxalinylene, phtalazinylene, imidazo[1 ,2-a]pyridinene, imidazo[2,1 -b]thiazolylene, cinnolinylene, triazinylene, benzofurazanylene, azaindolylene, benzimidazolylene, benzothienylene, thienopyridylene, thienopyrimidinylene, pyrrolopyridylene, imidazopyridylene, benzoazaindolene, 1 ,2,4-triazinylene, benzothiazolylene, furanylene, imidazolylene, indolylene, triazolylene, tetrazolylene, indolizinylene, isoxazolylene, isoquinolinylene, isothiazolylene, oxadiazolylene, pyrazinylene, pyridazinylene, pyrazolylene, pyridylene, pyrimidinylene, purinylene, quinazolinylene, quinolinylene, isoquinolylene, 1 ,3,4- thiadiazolylene, thiazolylene, triazinylene, isothiazolylene, carbazolylene, along with the corresponding groups obtained from the fusion thereof or fusion with the phenyl nucleus.

According to a further alternative embodiment, the compound P1 is of formula (II):

wherein:

- i is an integer ranging from 1 to 6, preferably equal to 2,

- j is an integer ranging from 1 to 6, preferably equal to i, and preferentially equal to 2,

- m is an integer ranging from 1 to 20,

- n is an integer between 1 and 10, preferably equal to 1 ,

- o is an integer between 1 and 10, preferably equal to 1 ,

- R1 , R3, R3 and R4, identical or different, represent a hydrogen atom or a C ₁ -C ₁₀ alkyl chain, preferably a hydrogen atom or a methyl group.

- -A"- represents a linear or branched Ci-C ₂₀ divalent hydrocarbon alkylene group, or a C ₅ -C ₂ o divalent cycloalkylene radical.

Preferably, -A"- represents a radical accordin to the formula:

A photocrosslinkable compound suitable for the implementation of the invention is for example PEG 400 Extended Urethane Dimethacrylate (X-726-0000 - ESSTECH, Inc.).

P1 is preferably present at a total content greater than or equal to 1 % by weight, in relation to the total weight of the photocrosslinkable composition, advantageously ranging from 1 to 20%, preferably from 2 to 15%, preferably from 5 to 10% by weight in relation to the total weight of the photocrosslinkable composition.

The composition according to the invention optionally comprises a mixture of different compounds P1 . Film-forming polymer P2

The composition according to the invention comprises at least one film-forming polymer P2, different to the photocrosslinkable compound P1 .

Preferably, the film-forming polymer P2 is a non-photocrosslinkable compound. The term "non-photocrosslinkable compound" refers to a compound inert to light exposure, i.e. that does not polymerize and/or is not crosslinked, unlike the photocrosslinkable compound P1 .

In particular, the film-forming polymer P2 is generally free from double ethylene bonds, such as acrylate and methacrylate groups.

The term "film-forming polymer" refers to, according to the invention, a polymer suitable for forming alone (i.e. in the absence of an auxiliary film-forming agent or an external stimulus for example such as UV), a film suitable for being isolated, particularly a continuous adherent film, on a substrate, particularly on nails.

A single film-forming polymer or a mixture of film-forming polymers may be used. This film-forming polymer may be chosen from the group consisting of radical or polycondensate type synthetic polymers, polymers of natural origin, and mixtures thereof.

A film-forming polymer suitable for the invention may be chosen from polysaccharide derivatives, such as cellulose or guar gum derivatives. One preferential polysaccharide derivative suitable for the invention may be nitrocellulose or a polysaccharide ester or alkylether.

The term "polysaccharide ester or alkylether" refers to a polysaccharide consisting of repeat units comprising at least two identical or different rings and having a degree of substitution per saccharide unit between 1 .9 and 3, preferably between 2.2 and 2.9, and more particularly between 2.4 and 2.8. The term substitution refers to the functionalization of hydroxyl groups into ester and/or alkylether functions, and/or the functionalization of carboxyl groups into ester functions.

In other words, it may consist of a polysaccharide, partially or totally substituted with ester and/or alkylether groups. Preferably, the hydroxyl groups may be substituted with C ₂ -C ₄ ester and/or alkylether functions.

Particular mention may be made of cellulose esters (such as cellulose acetobutyrates or cellulose acetopropionates), cellulose alkylethers (such as ethylcelluloses), and ethylguars.

A film-forming polymer suitable for the invention may be chosen from synthetic polymers such as polyurethanes, acrylic polymers, vinyl polymers, polyvinylbutyrals, alkyd resins and ketone/aldehyde resins, resins from aldehyde condensation products, such as aryl sulfonamide formaldehyde resins such as toluene sulfonamide formaldehyde resin, aryl-sulfonamide epoxy resins or ethyl tosylamide resins.

In particular, it may consist of(meth)acrylate homopolymers and copolymers.

A film-forming polymer suitable for the invention may also be chosen from polymers of natural origin, such as plant resins such as dammars, elemi, copals, benzoin; gums such as shellac, sandarac and mastic.

As a film-forming polymer, the toluene sulfonamide formaldehyde resins "Ketjentflex MS80" from AKZO or "Santolite MHP", "Santolite MS 80" from FACONNIER or "RESIMPOL 80" from PAN AMERICANA, the alkyd resin "BECKOSOL ODE 230-70-E" from DAINIPPON, the acrylic resin "ACRYLOID B66" from ROHM & HAAS, the polyurethane resin "TRIXENE PR 4127" from BAXENDEN, the acetophenone/formaldehyde resin marketed under the reference Synthetic Resin SK by Degussa may notably be used.

According to one preferred particular embodiment, the film-forming polymer P2 is chosen from the group consisting of polysaccharides and polysaccharide derivatives, preferably from nitrocellulose and polysaccharide ethers and esters, particularly C ₂ -C ₄ , and more preferentially from cellulose acetobutyrates, cellulose acetopropionates, ethylcelluloses, ethylguars, and mixtures thereof.

According to one particularly preferred embodiment, the film-forming polymer P2 is chosen from the group consisting of nitrocellulose, cellulose acetopropionate, cellulose acetobutyrate, and (meth)acrylate homopolymers and copolymers.

Advantageously, the film-forming polymer P2 is nitrocellulose.

P2 is preferably present at a total content greater than or equal to 1 % by weight, in relation to the total weight of the photocrosslinkable composition, advantageously ranging from 1 to 30%, preferably from 10 to 30%, preferably from 15 to 25% by weight in relation to the total weight of the photocrosslinkable composition.

The composition according to the invention optionally comprises a mixture of different polymers P2.

According to one embodiment, the composition according to the invention has a weight ratio between P1 and P2 less than or equal to 1 .5, preferably less than or equal to 1 .0, preferentially ranging from 0.1 to 1 .0, and advantageously from 0.2 to 0.5.

Photoinitiator

The composition according to the invention comprises at least one photoinitiator. The photoinitiators suitable for use according to the present invention are known in the art and are described, for example in "Les photoinitiateurs dans la reticulation des revetements", G. Li Bassi, Double Liaison - Chimie des Peintures, No. 361 , November 1985, p.34-41 ; "Applications industrielles de la polymerisation photoinduite", Henri Strub, L'Actualite Chimique, February 2000, p.5-13; and "Photopolymeres: considerations theoriques et reaction de prise", Marc, J.M. Abadie, Double Liaison - Chimie des Peintures, No. 435-436, 1992, p.28-34.

These photoinitiators include:

a-hydroxyketones, marketed for example under the names DAROCUR® 1 173 and 4265, IRGACURE® 184, 2959, and 500 by BASF, and ADDITOL® CPK by

CYTEC,

a-aminoketones, marketed for example under the names IRGACURE® 907 and 369 by BASF,

aromatic ketones marketed for example under the name ESACURE® TZT by LAMBERTI. Mention may also be made of thioxanthones marketed for example under the name ESACURE® ITX by LAMBERTI, and quinones. These aromatic ketones generally require the presence of a hydrogen donor compound such as tertiary amines and particularly alkanolamines. Mention may particularly be made by the tertiary amine ESACURE® EDB marketed by LAMBERTI.

a-dicarbonyl derivatives of which the most common is benzyl dimethyl ketal marketed under the name IRGACURE® 651 by BASF. Further commercial products are marketed by LAMBERTI under the name ESACURE® KB1 , and - acylphosphine oxides, such as for example bis-acylphosphine oxides (BAPO) marketed for example under the names IRGACURE® 819, 1700, and 1800,

DAROCUR® 4265, LUCIRIN® TPO, and LUCIRIN® TPO-L by BASF. Preferably, the photoinitiator of the composition according to the invention is chosen from the group consisting of α-hydroxyketones, a-aminoketones, aromatic ketones preferably associated with a hydrogen donor compound, aromatic a-diketones, acylphosphine oxides, and mixtures thereof.

A mixture of photoinitiators absorbing light radiation at various wavelengths is preferably used in the photocrosslinkable composition according to the invention. The absorption spectrum of the photocrosslinkable composition can thus be adapted to the emission spectrum of the light sources used. Preferably, the composition according to the invention comprises a mixture of two different photoinitiators, such as for example a mixture of an a-hydroxyketone and an acylphosphine oxide.

As a photoinitiator mixture, mention may be made of a mixture of IRGACURE® 184 (BASF) and LUCIRIN® TPO-L (BASF).

A particular group of photoinitiators suitable for use in the photocrosslinkable cosmetic compositions according to the present invention is that of copolymerizable photoinitiators. It consists of molecules comprising both a photoinitiator group capable of photoinduced radical splitting and at least one double ethylene bond. The photoinitiators in this group offer the advantage, in relation to the conventional photoinitiators listed above, of being suitable for being incorporated, via the double bond, into the macromolecular system. This possibility reduces the content of free residual photoinitiators not having undergone photoinduced radical splitting and thus enhances the safety of the layer C1 .

As examples of such copolymerizable photoinitiators, mention may be made of benzophenone acrylate derivatives marketed by CYTEC under the names EBECRYL® P36, EBECRYL® P37.

In one preferred embodiment of the invention, polymer photoinitiators or photoinitiators bound onto a high molar mass molecule are used. The choice of such a high mass photoinitiator offers the same advantage as selecting only polymeric copolymerizable compounds, i.e. enhanced safety of the photocrosslinkable cosmetic compositions due to the absence of very reactive molecules liable to diffuse to neighboring biological substrates. The mean molar mass by weight of the photoinitiator is preferably at least equal to 500 g/mol.

For example, mention may be made of an a-hydroxyketone oligomer corresponding to the following formula:

and which is marketed under the name ESACURE® KIP 150 by LAMBERTI. The polymer on which the photoinitiator group is bound may optionally comprise one or a plurality of double ethylene bonds for optionally incorporating, into the macromolecular network, photoinitiator molecules not having undergone photoinduced splitting.

As examples of such high molar mass photoinitiators bearing double ethylene bonds, mention may be made of those corresponding to the following formulae:

o o

avec n = 1 a 20 R = H -O ^{^} ^C— CH, ou — O CH=CH ₇

II

CH ₉

These structures are described in the following articles: S. Knaus, Pure Appl. Chem., A33(7), 869 (1996); S. Knaus, J. Polym. Sci, Part A = Polym. Chem., 33, 929 (1995); and R. Liska, Rad'Tech Europe 97, Lyon, F, 1997, Conference Proceedings.

The photoinitiator content is dependent on a large number of factors such as the reactivity of the various constituents of the mixture, the presence of pigments or dyes, the crosslinking density sought, the intensity of the light source or the exposure time.

In order to obtain satisfactory mechanical properties, the photoinitiator(s) is (or are) preferably present in a total content greater than or equal to 0.1 % by weight in relation to the total weight of the photocrosslinkable composition, preferably from 1 to 5% by weight in relation to the total weight of the photocrosslinkable composition.

Preferably, the photoinitiator(s) is (or are) present in a total content greater than or equal to 0.1 % by weight in relation to the total weight of the photocrosslinkable compound(s), preferably from 1 % to 15% by weight in relation to the total weight of the photocrosslinkable compound(s) P1 .

Solvents The composition according to the present invention generally comprises at least one solvent chosen from physiologically acceptable organic and inorganic solvents.

The suitable solvents may particularly be chosen from:

- liquid ketones at ambient temperature such as methylethylketone, methylisobutylketone, diisobutylketone, isophorone, cyclohexanone and acetone,

- liquid alcohols at ambient temperature such as ethanol, isopropanol, diacetone-alcohol, 2-butoxyethanol and cyclohexanol,

- liquid glycols at ambient temperature such as ethyleneglycol, propyleneglycol, pentyleneglycol and glycerol,

- liquid propyleneglycol ethers at ambient temperature such as propyleneglycol monomethylether, propyleneglycol monomethyl ether acetate and dipropyleneglycol mono-n-butylether,

- short-chain esters (comprising in total from 3 to 8 carbon atoms) such as ethyl acetate, methyl acetate, propyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, ter-butyl acetate and isopentyl acetate,

- liquid alkanes at ambient temperature such as decane, heptane, dodecane and cyclohexane,

- liquid aromatic hydrocarbons at ambient temperature such as toluene and xylene,

- liquid silicones at ambient temperature, and

mixtures thereof.

The composition according to the invention preferably comprises so-called volatile solvents.

The term "volatile solvent" refers to a solvent capable of evaporating on contact with keratin matter, in less than one hour, at ambient temperature and at atmospheric pressure.

The volatile solvent(s) according to the invention are liquid solvents at ambient temperature, having a vapor pressure different to zero, at ambient temperature and atmospheric pressure, particularly ranging from 0.13 Pa to 40,000 Pa (from 10 ^~3 to 300 mm Hg), particularly ranging from 1 .3 Pa to 13,000 Pa (from 0.01 to 100 mm Hg), and more specifically ranging from 1 .3 Pa to 1300 Pa (from 0.01 to 10 mm Hg).

On the other hand, a "non-volatile solvent" evaporates on contact with keratin matter in more than one hour, at ambient temperature and atmospheric pressure. The total solvent content in the composition may range from 5% to 95% by weight, in relation to the total weight of the composition.

According to one embodiment, the volatile solvent content in the composition ranges from 30% to 90%, preferably from 50% to 80% in relation to the total weight of said composition.

Preferably, the composition comprises a solvent chosen from liquid alcohols at ambient temperature, such as ethanol and isopropanol, and short-chain esters comprising in total from 3 to 8 carbon atoms, such as ethyl acetate and butyl acetate, and mixtures thereof.

Preferably, the solvent of the composition according to the invention is ethyl acetate.

Adjuvants

The composition according to the invention may further comprise adjuvants, or additives, particularly chosen from pigments and dyes, plasticizers, coalescing agents, preservatives, waxes, thickeners, perfumes, UV filters, cosmetic active substances for nail care, spreading agents, anti-foaming agents and dispersing agents.

The coloring agent(s) is (or are) present in a total content greater than or equal to 0.1 % by weight in relation to the total weight of the layer, ranging preferably from 0.1 to 5%, advantageously from 0.2 to 1 % by weight in relation to the total weight of the layer.

Obviously, those skilled in the art will take care to choose these optional adjuvants or additives such that the advantageous properties of the composition according to the invention are not, or are practically not, altered by the envisaged addition.

If the composition comprises pigments and/or dyes, it is particularly advisable to adapt the absorption spectrum of the pigments and/or dyes used to that of the photoinitiators, or conversely the absorption spectrum of the photoinitiators to that of the pigments and/or dyes used, so as to prevent both types of compounds from absorbing light at the same wavelengths. Indeed, the absorption of light by the pigments and/or dyes would render the photoinitiators present beyond a specific depth of the coat almost completely ineffective.

Preferably, the composition according to the invention is transparent.

As used herein, the term transparent denotes that the composition has a HAZEBYK index of less than 5 as measured with a KYKHAZEGLOSS type gloss meter. One particular composition according to the invention comprises, or consists of: - from 1 % to 10%, preferably from 5% to 10%, of a photocrosslinkable urethane dimethacrylate compound comprising a poly(ethyleneglycol) chain,

- from 10% to 30%, preferably from 15% to 25%, of nitrocellulose, - from 30% to 90%, preferably from 60% to 80%, of ethyl acetate,

- from 0.5% to 5%, preferably from 1 % to 3%, of an a-hydroxyketone photoinitiator, and

- from 0.5% to 3%, preferably from 0.5% to 2%, of an acylphosphine oxide photoinitiator.

The composition according to the invention is typically intended to be used as a finishing composition.

In particular, the composition according to the invention is typically intended to be applied onto a nail, or false nail, previously coated with one or a plurality of layers of conventional, optionally colored, nail varnish, or an adhesive flexible material.

As such, the present invention relates to a makeup and/or care method of a nail and/or false nail, comprising the following steps.

a) applying a photocrosslinkable composition according to the invention as defined above onto a nail or false nail coated with a varnish composition or an adhesive flexible material, whereby a coat consisting of at least one layer of said photocrosslinkable composition is deposited, and b) exposing the coated nail or false nail obtained following step a) to UV or visible light radiation, whereby the photocrosslinking of the photocrosslinkable compound P1 of said composition is carried out.

The radiation suitable for the crosslinking of the photocrosslinkable composition according to the present invention has a wavelength between 210 and 600 nm, preferably between 250 and 420 nm, preferably between 350 and 410 nm. The use of lasers may also be envisaged.

In one preferred embodiment of the invention, a LED lamp or an UV lamp and particularly a mercury vapor lamp, optionally doped with further elements, such as gallium, suitable for modifying the emission spectrum of the light source, is used.

The exposure time of the deposited coat to radiation is dependent on various factors such as the chemical nature and content of the reactive compounds or the crosslinking density sought. For nail varnishes, it would generally be sought to obtain satisfactory results for an exposure time between 10 seconds and 10 minutes, preferably between 30 seconds and 5 minutes.

Such a method may use a UV lamp having a power of approximately 36 W.

Preferably, the thickness after drying the coat of photocrosslinkable composition deposited in step a) is less than or equal to 100 μηι, preferably less than or equal to 50 μηι.

The crosslinked coat obtained from the crosslinking in step b) exhibits a significant stability over time, in terms of chipping resistance and gloss, particularly over the course of at least one week. It thus proves to be resistant to water, friction and shocks, and does not exhibit significant wear or chipping in this interval.

This coat is also capable of being solubilized or increasing in volume and thus weight when placed in contact with a standard makeup removal solvent. This ability to be solubilized or swell, displayed by the crosslinked coat, is specifically advantageous for the removal thereof when applied onto the surface of a nail or false nail. Indeed, the coat may be removed readily merely by means of makeup removal using a conventional solvent.

In this way, the composition according to the invention is advantageously suitable for being removed using standard solvents used in the field of nail varnish, and particularly using acetone and ethyl acetate, and mixtures thereof.

The composition according to the invention is easier to remove than existing photocrosslinkable top coats due to a higher proportion of polymer.

The present invention also relates to a makeup removal method of a nail and/or false nail, comprising the application of a makeup removal composition, such as a standard solvent described above, onto a nail or false nail coated with at least one layer obtained by crosslinking a layer of composition according to the invention, whereby said crosslinked layer is removed, optionally along with a layer of varnish situated between the nail or false nail and said crosslinked layer.

The present invention also relates to a kit comprising:

a photocrosslinkable cosmetic composition according to the invention, an abrasive material having a granulometry greater than or equal to 200 μηι, preferably less than 300 μηι, advantageously comprised from 220 μηι to 280 μηι, and

a LED lamp or an UV lamp. The present invention also relates to a makeup and/or care method of a nail and/or false nail, comprising the following steps:

rubbing the surface of a nail or false nail with an abrasive material having a granulometry greater than or equal to 200 μηι, preferably less than 300 μηι, advantageously comprised from 220 μηι to 280 μηι,

applying a photocrosslinkable composition according to the invention, whereby a coat consisting of at least one layer of said photocrosslinkable composition is deposited, and

) exposing the coated nail or false nail obtained following step ii) to a LED lamp or an UV lamp, whereby the photocrosslinking of the photocrosslinkable composition is carried out.

Usually, the rubbing step is performed for less than 10 seconds, preferably less than 5 seconds, for example for approximately 3 seconds.

Between step i) and step ii), the nail or false nail may be coated with a varnish composition or an adhesive flexible material, so that the photocrosslinkable composition according to the invention is deposited onto the coat of varnish or onto the adhesive flexible material.

Examples

The present invention will now be illustrated using the following example. A "Salon effects" adhesive flexible material from Sally Hansen is applied to the nail.

A photocrosslinkable composition according to the invention is then applied onto the nail coated with the adhesive flexible material. After drying for approximately 5 minutes, the nail covered and coated with the photocrosslinkable composition is then crosslinked for 60 seconds under an "OPI GelColor" lamp from OPI (wavelength: 404 nm).

The ingredients of the composition are introduced into an opaque flask and placed under stirring protected from light with a Rayneri laboratory mixer until a homogeneous mixture is obtained. An aluminum foil will have been previously positioned on the top of the container to prevent the solvents from evaporating.

The nail makeup or care material obtained can be removed with a solvent such as acetone.