WO2012130602A1 - Photo-crosslinkable nail varnishes free of unsaturated monomers - Google Patents

Abstract

The invention relates to a photo-crosslinkable cosmetic composition, which is free of reactive monomers with a molecular mass of less than 400 g/mol comprising one or more ethylenic double bonds: -at least onepolymer comprising ethylenic double bonds, themeannumber of ethylenic double bondsper polymer molecule being greater than 1, the said at least onepolymer comprising at least one polyether polymer containing (meth)acrylate groupsmodified by a reaction with an amino group, and -at least one radical photoinitiator. The invention also relates to a cosmetic process for coating the nails or false nails using such a composition.

Description

Photo-crosslinkable nail varnishes free of unsaturated monomers

The present invention relates to photo-crosslinkable, monomer-free cosmetic compositions, in particular nail varnishes, and also to a process for depositing a crosslinked coating in situ using these compositions.

Nail varnish compositions can be used as varnish base, as a nail makeup product, as a finishing composition, also known as a top coat, to be applied over the nail makeup product, or else as a cosmetic nailcare product. These compositions may be applied onto either human nails or false nails.

Liquid cosmetic compositions which, after deposition on the nail and exposure to actinic radiation undergo polymerization and/or crosslinking reactions in situ resulting in polymer networks that are usually crosslinked, are known in the field of nail varnishes. Such photo-polymerizable and/or photo-crosslinkable compositions are described, for example, in patents CA 1 306 954, US 5 456 905, US 7 375 144 and FR 2 823 105.

These compositions generally contain one or more polymers and/or prepolymers comprising polymerizable ethylenic double bonds, one or more reactive monomers containing double bond(s), at least one photo-initiator, optionally one or more agents for inhibiting the premature polymerization of the components, or alternatively photosensitizers for modifying the absorption spectrum of the photo-initiating system.

The main drawback of these compositions lies in the toxicity of the unsaturated monomers used. Specifically, these highly reactive, low molecular weight molecules diffuse readily into the subjacent and adjacent substrates, where they react with biological molecules. The Applicant has sought to solve this toxicity problem of the photo- crosslinkable cosmetic compositions of the prior art by developing photo-crosslinkable cosmetic compositions containing, as sole polymerizable or crosslinkable reactive components, macromolecular compounds, i.e. reactive components whose molecular mass is high enough to prevent them from diffusing into the neighbouring biological substrates.

Patent US 7 375 144 describes photo-crosslinkable compositions free of monoacrylate monomers, which are capable of polymerizing under UV radiation. However, the compositions described comprise large amounts of low molecular mass diacrylate compounds that can diffuse into the subjacent and adjacent substrates and react with biological molecules.

Patent FR 2 823 105 describes photo-crosslinkable compositions that are free of compounds with molecular masses of less than 500 g/mol. However, the described compositions do not make it possible to obtain compositions whose viscosity is suitable for them to be applied correctly to the nails, or do not make it possible to obtain films whose rigidity or cohesion is sufficient to obtain good wear properties on the nail.

Consequently, one subject of the present invention is photo-crosslinkable cosmetic compositions free of reactive monomers containing ethylenic double bond(s), comprising:

- at least one polymer comprising ethylenic double bonds, the mean number of ethylenic double bonds per polymer molecule being greater than 1, the said at least one polymer comprising at least one poly ether polymer containing (meth)acrylate groups modified by reaction with an amino group, and

- at least one radical photoinitiator. Preferably, this composition comprises at least two polymers comprising ethylenic double bonds, the mean number of ethylenic double bonds per polymer molecule being greater than 1, the said at least two polymers comprising at least one polyether polymer containing (meth)acrylate groups modified by reaction with an amino group and at least one polyether polymer containing (meth)acrylate groups.

Throughout the application, a polyether polymer containing (meth)acrylate groups, without modification by reaction with an amino group being specified, is a polyether polymer containing (meth)acrylate groups not modified by reaction with an amino group.

In particular, the photo-crosslinkable cosmetic compositions free of reactive monomers containing ethylenic double bond(s) are free of (meth)acrylate monomers and of urethane (meth)acrylate monomers.

The term "(meth)acrylate monomer" means any compound comprising only one (meth)acrylate function or group of formula H₂C=C(R)-C(0)-0-X, with R = H or CH₃ and X is the radical onto which is grafted this (meth)acrylate function.

The term "urethane (meth)acrylate monomer" means any compound comprising at least one urethane function -0-C(0)- H- and at least one (meth)acrylate function of formula H₂C=C(R)-C(0)-0-X, with R = H or CH₃ and X is the radical onto which is grafted this (meth)acrylate function.

Preferably, the said photo-crosslinkable cosmetic composition is a nail varnish.

A subject of the invention is also a cosmetic process for coating nails or false nails using these photo-crosslinkable cosmetic compositions defined previously.

Hereinafter in this patent application, the following definitions apply:

- (poly)ol: a monoalcohol or a polyol, preferably a diol, advantageously containing from 2 to 20 carbon atoms and more preferentially from 2 to 6 carbon atoms; - (poly)alkoxylated: one or more divalent groups -R-0-, R being a Ci-C₆ alkylene, preferably -R-O- being (CH₂-CH₂-0)_n or (CH₂-CH₂-CH₂-0)_n, n being an integer greater than 1, for example between 1 and 1000;

- (poly)hydroxylated: one or more groups -OH.

As indicated above, the mean number of ethylenic double bonds borne by the polymer(s) forming the crosslinked polymer network of the final cured coating must be greater than 1. Specifically, a polymerizable system formed from molecules (monomers, oligomers or polymers) each bearing only one double bond forms, after reaction of all of the double bonds, a macromolecular system containing linear or branched but non- crosslinked chains. Only the presence of a certain fraction of molecules bearing at least two double bonds and acting, as a result, as crosslinking agent makes it possible to obtain a crosslinked polymer system.

In the practice of the present invention, the mean number of fractions per polymer molecule is preferably greater than or equal to 2 and advantageously between 2 and 6, limits inclusive.

As explained above, the harmlessness of the photo-crosslinkable cosmetic compositions of the present invention is due to the fact that the polymer(s) comprising one or more ethylenic double bonds have a molecular mass that is sufficient to prevent them from diffusing towards and into the neighbouring biological substrates. The term "sufficient molecular mass" means a weight-average molecular mass of greater than or equal to 400. In particular, the weight-average molecular mass may range from 400 to 5000.

In one preferred embodiment, the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group according to the invention have a weight-average molecular mass of greater than or equal to 400, especially ranging from 450 to 5000 and preferably ranging from 500 to 3000. Photo-crosslinkable polymers

A composition in accordance with the present invention comprises polymers bearing ethylenic double bonds and having a suitable molar mass.

More specifically, a composition according to the invention comprises at least one polyether polymer containing (meth)acrylate groups modified by reaction with an amino group.

Preferably, a composition according to the invention also comprises a polyether polymer containing (meth)acrylate groups (not modified by reaction with an amino group). a) Polyether polymers containing (meth)acrylate groups modified by reaction with an amino group

A polyether polymer containing (meth)acrylate groups modified by reaction with an amino group present in a composition in accordance with the invention preferably comprises at least 2 (meth)acrylate functions, preferably from 2 to 4 (meth)acrylate functions and more preferentially from 2.5 to 3.5 (meth)acrylate functions.

Such a polymer preferably has a molecular mass of between 400 g/mol and 1500 g/mol and more preferentially between 500 g/mol and 1000 g/mol.

This polymer is preferably obtained by esterification with the (meth)acrylic acid, on the one hand, or with all of the end hydroxyl groups derived from Ci_-6 alkylene glycol homopolymers or copolymers, such as polyethylene glycol, polypropylene glycol, copolymers of ethylene oxide and of propylene oxide preferably having a weight-average molecular mass of less than 10 000 g/mol, polyethoxylated or polypropoxylated glycerols, polyethoxylated or polypropoxylated trimethylolpropanes, polyethoxylated or polypropoxylated pentaerythritols, polyethoxylated or polypropoxylated bis- trimethylolpropanes and polyethoxylated or polypropoxylated bis-pentaerythritols. Such polymers are especially described in US patent No. 5 543 557. According to the invention, at least some, or all, of the ethylenic groups of the polyether polymer(s) containing (meth)acrylate groups are modified by reaction with an amino group. Such polymers may advantageously correspond to formula (Γ) below.

Such polymers in accordance with the invention preferably comprise polymers partially modified by reaction with an amino group, as described in patent application US 2009/0 098 304.

These polymers may especially be obtained by reaction between some of the ethylenic groups of the polyether polymer containing (meth)acrylate groups as described previously and a primary or secondary amine, according to the following reaction scheme (Michael addition):

(Formula I)

R'

which may be identical or different, represent a single or double bond;

ALK¹ and AL ², which may be identical or different, represent a (Ci-C₆)alkyl group such as ethyl or propyl; x¹ and x², which may be identical or different, represent an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

R and R , which may be identical or different, represent a hydrogen atom or a (C|- C₆)alkyl group such as methyl;

X, which may be identical or different, represent a CH₂ group when is a double bond, or X represents an amino group CH₂NR_aR_b when is a single bond with R_a representing an alkyl optionally substituted with a hydroxyl, alkoxy, tertiary amine or aryl, and R_b representing a hydrogen or an alkyl optionally substituted with a hydroxide, alkoxy, tertiary amine or aryl. R_a and R_b may be linked together to form a ring;

* R' preferably representing: i) a group of formula (ΙΓ) below:

in which formula (ΙΓ):

- ALK³ represents a (C[-C₆)alkyl group such as ethyl or propyl;

- x³ represents an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

RECTIFIED SHEET RULE 91 ISA/EP R³ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

X being as defined previously;

ii) a group of formula (III') below:

O

X in which formula (ΙΠ'):

- ALK⁴ represents a (Ci-C₆)alkyl group such as ethyl or propyl;

- x⁴ represents an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

- R⁴ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

- x being as defined previously;

iii) a group of formula (IV) below:

(*) CH₂— O ALK⁵ O—ALK⁶ (IV) in which formula (IV):

- ALK⁵ and ALK⁶, which may be identical or different, represent a (Ci-C₆)alkyl group such as ethyl or propyl; - X being as defined previously; or

iv) a group of formula (V) below:

in which formula (V):

- ALK⁷ and ALK⁸, which may be identical or different, represent a (Ci-C₆)alkyl group such as ethyl or propyl;

- x⁷ and x⁸, which may be identical or different, represent an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

- R⁷ and R⁸, which may be identical or different, represent a hydrogen atom or a (Ci- C₆)a]kyl group such as methyl;

- R'" being a hydrogen atom or a (Ci-C₆)alkyl group such as ethyl, or an alkoxy group such as methoxy, or the group of formula (VT):

X

in which formula (VP):

- ALK⁹ represents a (Ci-C₆)alkyl group such as ethyl or propyl;

- x⁹ represents an integer greater than or equal to 1 , for instance between 1 and 1000 inclusive; - R⁹ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

- X being as defined previously;

- and mixtures thereof;

* R" representing a hydrogen atom or a (Ci-C₆)alkyl group such ethyl, or an alkoxy group such as methoxy, or the group of formula (VII'):

X

in which formula (VIP):

- ALK¹⁰ represents a (Ci-C₆)alkyl group such as ethyl or propyl;

- x¹⁰ represents an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

- R¹⁰ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

- and mixtures thereof.

It is understood in the preceding formulae that these formulae comprise at least one group X representing an amino group (as defined previously) when the polyether (meth)acrylate is modified by reaction with an amino group.

The reaction between the (meth)acrylate and the amine does not require either catalyst or solvent.

Preferably, the mole ratio between the amine and the ethylenic groups of the polyether polymer containing (meth)acrylate groups is between 0.01 : 1 and 0.5: 1.

Such polymers are sold, for example, by the company Cytec under the names Ebecryl^® LEO 10551 : molar mass 500 g/mol, on average 2.5 acrylate functions per molecule, Ebecryl^® LEO 10552: molar mass 1000 g/mol, on average 3.5 acrylate functions per molecule, or alternatively such polyether polymers modified by reaction with an amino group of suitable molar mass are sold, for example, under the names CN501 and CN550 by the company Sartomer, or under the names Ebecryl^® 80, Ebecryl^® 81 and Ebecryl^® 83 by the company Cytec, and under the names Photomer^® 5662 and Photomer^® 5930 by the company Cognis.

The polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group are preferably present in a total content of greater than or equal to 20% by weight relative to the total weight of the photo-crosslinkable cosmetic composition, and advantageously between 30% and 70% by weight relative to the total weight of the photo-crosslinkable cosmetic composition, limits inclusive.

b) Polyether polymer containing (meth)acrylate group(s)

A polyether polymer containing (meth)acrylate groups preferably present in a composition in accordance with the invention preferably comprises at least 2 (meth)acrylate functions, preferably from 2 to 4 (meth)acrylate functions and more preferentially from 2.5 to 3.5 (meth)acrylate functions.

Such a polymer preferably has a molecular mass of between 400 g/mol and 1500 g/mol and more preferentially between 500 g/mol and 1000 g/mol.

This polymer is preferably obtained by esterification with the (meth)acrylic acid, on the one hand, or with all of the end hydroxyl groups derived from Ci_-6 alkylene glycol homopolymers or copolymers, such as polyethylene glycol, polypropylene glycol, copolymers of ethylene oxide and of propylene oxide preferably having a weight-average molecular mass of less than 10 000 g/mol, polyethoxylated or polypropoxylated glycerols, polyethoxylated or polypropoxylated trimethylolpropanes, polyethoxylated or polypropoxylated pentaerythritols, polyethoxylated or polypropoxylated bis- trimethylolpropanes and polyethoxylated or polypropoxylated bis-pentaerythritols. Such polymers are especially described in US patent No. 5 543 557. Preferably, the polyether polymer(s) containing (meth)acrylate groups are obtained by esterification with the (meth)acrylic acid, on the one hand, or all of the end hydroxyl groups derived from (poly)hydroxylated, preferably polyhydroxylated, and (poly)alkoxylated, preferably polyalkoxylated, compounds.

Preferably, polyether polymer containing (meth)acrylate groups is chosen from the compounds of formula (I) below:

R"

in which formula (I):

ALK¹ and ALK², which may be identical or different, represent a (C|-C₆)alkyl group such as ethyl or propyl; x¹ and x², which may be identical or different, represent an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

R¹ and R², which may be identical or different, represent a hydrogen atom or a (Cp C₆)alkyl group such as methyl;

* R' preferably representing: i) a group of formula (II) below:

in which formula (II):

- AL ³ represents a (Ci-C₆)alkyl group such as ethyl or propyl;

- x³ represents an integer greater than or equal to 1, for instance between I and 1000 inclusive;

- R³ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

ii) a group of formula (III) below:

in which formula (III):

- ALK⁴ represents a (Ci-C₆)alkyl group such as ethyl or propyl;

- x⁴ represents an integer greater than or equal to 1 , for instance between 1 and 1000 inclusive;

- R⁴ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

iii) a group of formula (IV) below:

CH₂— O— ALK^S O ALK⁶ (IV) in which formula (IV): - ALK⁵ and ALK⁶, which may be identical or different, represent a (C|-C₆)alkyl such as ethyl or propyl; or

iv) a group of formula (V) below:

in which formula (V):

- ALK⁷ and ALK⁸, which may be identical or different, represent a (Ci-C6)alkyl group such as ethyl or propyl;

- x⁷ and x⁸, which may be identical or different, represent an integer greater than or equal to 1 , for instance between 1 and 1000 inclusive;

- R⁷ and R⁸, which may be identical or different, represent a hydrogen atom or a (Ci- C₆)alkyl group such as methyl;

RECTIFIED SHEET RULE 91 ISA/EP - R'" being a hydrogen atom or a (Ci-C₆)alkyl group such as ethyl, or an alkoxy group such as methoxy, or the group of formula (VI):

in which formula (VI):

- ALK⁹ represents a (CpC₆)alkyl group such as ethyl or propyl;

- x⁹ represents an integer greater than or equal to 1 , for instance between 1 and 1000 inclusive;

- R⁹ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

- and mixtures thereof;

* R" representing a hydrogen atom or a (C C₆)alkyl group such as ethyl, or an alkoxy group such as methoxy, or the group of formula (VII):

in which formula (VII):

- ALK¹⁰ represents a (Ci-C₆)alkyl group such as ethyl or propyl;

- x¹⁰ represents an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

- R¹⁰ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

- and mixtures thereof.

Preferably, the polyether polymer containing (meth)acrylate groups is chosen from polyethoxylated or polypropoxylated glyceryl triacrylates, polyethoxylated or polypropoxylated trimethylolpropane triacrylates, polyethoxylated or polypropoxylated bis- trimethylolpropane tetraacrylates, and polyethoxylated or polypropoxylated dipentaerythrityl pentaacrylates, and mixtures thereof.

Such polymers are sold by the company Cytec under the name Ebecryl^® LEO 10501; molecular mass 470 g/mol, on average 3 acrylate functions per molecule. Polypropoxylated glyceryl triacrylates are sold, for example, under the names SR 9019 and SR 9020 by the company Sartomer, or under the names OTA-480 and Ebecryl^® 53 by the company Cytec. Polyethoxylated trimethylolpropane triacrylates are sold, for example, under the names SR 454, SR 499, SR 502 and SR 415 by the company Sartomer, or under the names TMPEOTA and Ebecryl^® 160 by the company Cytec. Polypropoxylated trimethylolpropane triacrylates are sold, for example, under the name SR 492 by the company Sartomer.

The polyether polymer(s) containing (meth)acrylate groups are preferably present in a total content of greater than or equal to 20% by weight relative to the total weight of the photo-crosslinkable cosmetic composition, and advantageously between 30% and 70%) by weight relative to the total weight of the photo-crosslinkable cosmetic composition, limits inclusive.

The polyether polymer(s) containing (meth)acrylate groups and the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group are preferably present in a total content of greater than or equal to 50% by weight relative to the total weight of the photo-crosslinkable cosmetic composition, and advantageously between 55% and 99.9% by weight relative to the total weight of the photo-crosslinkable cosmetic composition, limits inclusive.

The polyether polymer(s) containing (meth)acrylate groups and the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group are preferably present in the composition in a respective total content such that the weight ratio of the polyester polymer(s) containing (meth)acrylate groups to the polyether polymer(s) containing (meth)acrylate groups is between 0.3 and 3, preferably between 0.5 and 2, limits inclusive. Photoinitiators

The photoinitiators that may be used in the cosmetic compositions of the present invention are also known in the art and are described, for example, in the following articles: "Les photoinitiateurs dans la reticulation des revetements [Photoinitiators in the crosslinking of coatings]", G. Li Bassi, Double Liaison - Chimie des Peintures, No. 361, November 1985, pages 34-41; "Applications industnelles de la polymerisation photoinduite [Industrial applications of photo-induced polymerization]", Henri Strub, L'Actualite Chimique, February 2000, pages 5-13; and "Photopolymeres: considerations theoriques et reaction de prise [Photopolymers: theoretical considerations and setting reaction]", Marc, J.M. Abadie, Double Liaison - Chimie des Peintures, No. 435-436, 1992, pages 28-34.

These photoinitiators include

• the oc-hydroxy ketones sold, for example, under the names Darocur^® 1173 and 4265, Irgacure^® 184, 2959 and 500 by the company BASF, and Additol^® CPK by the company Cytec,

· the oc-amino ketones sold, for example, under the names Irgacure® 907 and

369 by the company BASF,

• the aromatic ketones sold, for example, under the name Esacure^® TZT by Lamberti. Mention may also be made of the thioxanthones sold, for example, under the name Esacure^® ITX by Lamberti, and quinones. These aromatic ketones usually require the presence of a hydrogen-donating compound such as tertiary amines and especially alkanolamines. Mention may be made especially of the tertiary amine Esacure^® EDB sold by the company Lamberti. • -dicarbonyl derivatives, the most common representative of which is benzyl dimethyl ketal, sold under the name Irgacure^® 651 by BASF. Other commercial products are sold by the company Lamberti under the name Esacure^® KBl .

• acylphosphine oxides, for instance the bis-acylphosphine oxides (BAPOs) sold, for example, under the names Irgacure^® 819, 1700 and 1800, Darocur^® 4265,

Lucirin^® TPO and Lucirin^® TPO-L by the company BASF.

One particular group of photoinitiators that may be used in the photo- crosslinkable cosmetic compositions of the present invention is that of copolymerizable photoinitiators. These are molecules comprising both a photoinitiating group capable of photo-induced radical scission and at least one ethylenic double bond. The photoinitiators of this group have the advantage, over the standard photoinitiators mentioned above, of being able to be integrated, via the double bonds, into the macromolecular system. This possibility reduces the content of residual free photoinitiators that have not undergone a photoinduced radical cleavage and consequently improves the harmlessness of the cosmetic compositions.

Examples of such copolymerizable photoinitiators that may be mentioned include the benzophenone acryl derivatives sold by the company Cytec under the names Ebecryl^® P36 and Ebecryl^® P37.

In one preferred embodiment of the invention, use is made of polymer photoinitiators or photoinitiators attached to a high molecular weight molecule. The choice of such a high-mass photoinitiator has the same advantage as the selection of exclusively polymeric copolymerizable components, namely better safety of the photo-crosslinkable cosmetic compositions due to the absence of small, highly reactive molecules capable of diffusing to the neighbouring biological substrates. As for the copolymerizable components, the weight-average molecular weight of the photoinitiator is preferably at least equal to 500 g/mol. Mention may be made, by way of example, of the oc-hydroxy ketone oligomer corresponding to the following formula:

where n = 2 or J

and which is sold under the name Esacure^® KIP 150 by the company Lamberti.

The polymer to which the photoinitiator group is attached may optionally comprise one or more ethylenic double bonds optionally enabling the integration, into the macromolecular network, of photoinitiator molecules that have not undergone photo- induced scission.

Mention may be made, as examples of such high molecular weight photoinitiators bearing ethylenic double bonds, of those corresponding to the formulae below:

⁼ CHT

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

In the photo-crosslinkable cosmetic compositions of the present invention, use is preferably made of a mixture of photoinitiators that absorb light at different wavelengths. It is thus possible to adapt the absorption spectrum of the photo-crosslinkable cosmetic compositions to the emission spectrum of the light sources used.

The content of photoinitiator(s) used depends on a large number of factors such as, for example, the reactivity of the various components of the mixture, the presence of pigments or dyes, the desired crosslinking density, the intensity of the light source or the exposure time.

To obtain satisfactory mechanical properties, the radical photoinitiator(s) are preferably present in a total content of greater than or equal to 0.1% by weight relative to the total weight of the composition and preferably between 1% and 5% by weight relative to the total weight of the composition.

Preferably, the radical photoinitiator(s) are present in a total content of greater than or equal to 0.1% by weight relative to the total weight of the poly ether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group, and preferably between 0.5% and 3% by weight relative to the total weight the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group.

FILM-FORMING POLYMER

Preferably, the cosmetic compositions of the present invention comprise at least one film-forming polymer.

For the purposes of the present invention, the term "film-forming polymer" denotes a polymer that is capable, by itself (i.e. in the absence of an auxiliary film-forming agent or of an external stimulus, for instance UV) of forming an isolable and especially continuous and adherent film, on a support, especially on the nails.

A single film-forming polymer or a mixture of film-forming polymers may be used in the composition.

This film-forming polymer may be chosen from the group formed by synthetic polymers of radical type or of polycondensate type, and polymers of natural origin, and mixtures thereof.

A film-forming polymer that is suitable for use in the invention may be chosen in particular from: - polysaccharide derivatives, such as cellulose or guar gum derivatives. A preferential polysaccharide derivative that is suitable for use in the invention may be nitrocellulose or a polysaccharide ester or alkyl ether.

The term "polysaccharide ester or alkyl ether" denotes a polysaccharide formed from repeating units comprising at least two identical or different rings having a degree of substitution per saccharide unit of between 1.9 and 3, preferably between 2.2 and 2.9 and more particularly between 2.4 and 2.8. The term "substitution" denotes the functionalization of the hydroxyl groups into ester and/or alkyl ether functions, and/or the functionalization the carboxylic groups into ester functions.

In other words, it may be a polysaccharide that is partially or totally substituted with ester and/or alkyl ether groups. Preferably, the hydroxyl groups may be substituted with ester and/or C₂-C₄ alkyl ether functions.

Mention may be made in particular of cellulose esters, such as cellulose acetobutyrates or cellulose acetopropionates; cellulose alkyl ethers such as ethylcelluloses, and ethyl guars;

- synthetic polymers such as polyurethanes, acrylic polymers, vinyl polymers, polyvinyl butyrals, alkyd resins and ketone/aldehyde resins, resins derived from aldehyde condensation products, such as arylsulfonamide-formaldehyde resins, for instance toluenesulfonamide-formaldehyde resin, arylsulfonamide-epoxy resins or ethyl tosylamide resins;

- polymers of natural origin, such as plant resins, such as dammar resins, elemi gums, copal resins, and benzoin; gums such as shellac, sandarac gum and gum mastic.

Use may especially be made, as film-forming polymers, of the toluenesulfonamide/formaldehyde resins Ketjentflex MS80 from the company Akzo or Santolite MHP, Santolite MS 80 from the company Faconnier or Resimpol 80 from the company Pan Americana, the alkyd resin Beckosol ODE 230-70-E from the company Dainippon, the acrylic resin Acryloid B66 from the company Rohm & Haas, the polyurethane resin Trixene PR 4127 from the company Baxenden or the acetophenone/formaldehyde resin sold under the reference Synthetic Resin SK by Degussa.

According to one particular preferred embodiment, the film-forming polymer is chosen from poly saccharides and polysaccharide derivatives, preferably from nitrocellulose and polysaccharide ethers and esters, especially C₂-C₄ ethers and esters, and is more preferentially chosen from cellulose acetobutyrate s, cellulose acetopropionates, ethylcelluloses and ethyl guars, and mixtures thereof.

According to one particularly preferred embodiment, the film-forming polymer is chosen from cellulose derivatives such as nitrocellulose, cellulose acetobutyrate and ethyl cellulose.

According to one embodiment, a composition according to the invention comprises a total content of film-forming polymer(s) of greater than or equal to 5%, in particular between 5% and 30% by weight, especially between 7.5% and 25% by weight and in particular between 10% and 20% by weight relative to the total weight of the nail varnish.

SOLVENTS

The photo-crosslinkable cosmetic compositions of the present invention may comprise at least one solvent chosen from physiologically acceptable organic solvents.

The said at least one organic solvent may be chosen in particular from:

a) ketones that are liquid at room temperature, such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, isophorone, cyclohexanone and acetone,

b) alcohols that are liquid at room temperature, such as ethanol, isopropanol, diacetone alcohol, 2-butoxyethanol or cyclohexanol,

c) glycols that are liquid at room temperature, such as ethylene glycol, propylene glycol or pentylene glycol and glycerol, d) propylene glycol ethers that are liquid at room temperature, such as propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and dipropylene glycol mono-n-butyl ether,

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

f) alkanes that are liquid at room temperature, such as decane, heptane, dodecane and cyclohexane,

g) aromatic hydrocarbons that are liquid at room temperature, such as toluene and xylene,

h) silicones that are liquid at room temperature, and

i) mixtures thereof.

The content of solvent in the composition may range from 5% to 50% by weight and preferably from 10% to 30% by weight relative to the total weight of the composition.

Preferably, the composition comprises a solvent chosen from alcohols that are liquid at room temperature, short-chain esters comprising in total from 3 to 8 carbon atoms, and a mixture thereof.

According to one particular embodiment of the composition according to the invention, the composition is free of solvent.

ADJUVANTS

The photo-crosslinkable cosmetic compositions of the present invention may also contain adjuvants, or additives, chosen especially from pigments and dyes, plasticizers, coalescers, preserving agents, waxes, thickeners, fragrances, UV-screening agents, cosmetic nailcare active agents, spreading agents, antifoams and dispersants. Preferably, the said photo-crosslinkable cosmetic compositions of the present invention comprise at least one colouring agent chosen from pigments and preferably from metal oxides, such as iron oxides. The colouring agent(s) are present in a total content of greater than or equal to

0.1% by weight relative to the total weight of the composition, and advantageously ranging from 0.2% to 1% by weight relative to the total weight of the composition.

Needless to say, a person skilled in the art will take care to select these optional adjuvants and additives such that the advantageous properties of the compositions according to the invention are not, or are virtually not, adversely affected by the envisaged addition.

When the composition comprises pigments and/or dyes, the absorption spectrum of the pigments and/or dyes used should in particular be adapted to that of the photoinitiators, or, conversely, the absorption spectrum of the photoinitiators should be adapted to that of the pigments and/or dyes used, so as to avoid these two types of compound absorbing light at the same wavelengths. Specifically, the absorption of light by the pigments and/or dyes would make the photoinitiators present virtually ineffective beyond a certain depth of coating.

A subject of the present invention is also a cosmetic process for coating natural nails or false nails. This process comprises:

a step of applying a photo-crosslinkable cosmetic composition containing, in a physiologically acceptable medium, (a) one or more oligomers and/or polymers comprising ethylenic double bonds, the mean number of ethylenic double bonds per oligomer and/or polymer molecule being greater than 1, and (b) at least one radical photoinitiator, so as to form a film on nails or false nails, and

a step of exposing the deposited film to radiation of a suitable wavelength for a time that is sufficient to induce crosslinking of the said film.

When the composition comprises a volatile solvent such as a volatile organic solvent, the film is exposed to the radiation after evaporation of the solvent or of the water.

One embodiment of the process according to the invention consists in successively performing the steps of applying the composition and exposing the film several times, in particular twice in succession.

According to another embodiment of the process according to the invention, this process comprises a preliminary step of applying a transparent coat to ensure good adhesion (or base coat) under the photo-crosslinkable cosmetic composition. Preferably, this coat for ensuring good adhesion, which is free of colouring agent, is transparent and the cosmetic composition comprises a colouring agent. Preferably, this coating for ensuring good adhesion is also a photo-crosslinkable cosmetic composition.

According to another embodiment of the process according to the invention, this process comprises a subsequent step of applying a transparent protective coat (or topcoats) over the photo-crosslinkable cosmetic composition. Preferably, this protective coat, which is free of colouring agent, is transparent and the cosmetic composition comprises a colouring agent. Preferably, this protective coat is also a photo-crosslinkable cosmetic composition. According to another particular embodiment of the process of the present invention, the keratin substrate (nails, false nails, eyelashes, false eyelashes, hair and hair prostheses) onto which is deposited the photo-crosslinkable cosmetic composition is already covered with a first non-crosslinkable cosmetic coating, such as a standard base coat or nail varnish. The photo-crosslinkable cosmetic composition then constitutes a protective coat (top coat) for the first non-crosslinkable cosmetic coating. The composition may also be deposited alone onto the nail to protect it. In this embodiment, the photo- crosslinkable cosmetic composition is preferably uncoloured, i.e. free of pigments and dyes.

The radiation suitable for crosslinking the cosmetic compositions of the present invention has a wavelength between 210 nm and 600 nm, preferably between 250 nm and 400 nm, preferably between 350 nm and 400 nm. The use of lasers may also be envisaged. In one preferred embodiment of the invention, use is made of a UV lamp and in particular a mercury-vapour lamp, the mercury optionally being doped with other elements, such as gallium, making it possible to modify the emission spectrum of the light source.

The exposure time of the deposited film to the radiation depends on various factors such as the chemical nature and the content of the reactive components or else the desired crosslinking density.

For nail varnishes, it will generally be sought to obtain satisfactory results for an exposition time between 1 and 20 minutes and preferably between 2 and 10 minutes.

This curing time preferably does not correspond to total crosslinking of the system, i.e. the reaction of all of the double bonds present. To ensure good wear of the nail varnishes over time, it is advantageous to obtain both a high crosslinking density at the surface of the film, which ensures good mechanical strength, and low crosslinking at the coating-substrate interface, which is essential for good adhesion of the deposited film to the substrate.

Such a process may use a UV lamp with a power rating of about 36 W. Exemplary embodiment:

A nail varnish was prepared, having the following composition:

- Polyether polymer containing (meth)acrylate groups modified by reaction with an amino group (Ebecryl^® LEO 10552 from Cytec): 43%

- Polyether polymer containing (meth)acrylate groups (Ebecryl^® LEO 10501 from Cytec): 52.8%

- Photoinitiator (Additol CPK from Cytec): 4%

- Pigment (Sunpuro Red Iron Oxide C33-8001 from Sun) 0.2%

The composition of the example is applied to the nails in the form of a film about 50 μπι thick, and this film is irradiated for 2 minutes with UV radiation emitted by a Philips Original UVA lamp (36 W) sold by the company Philips, the effective wavelength range of which is from 340 to 365 nm. The lamp is placed at a distance of about 50 cm from the nails and, during the exposure time, the hands are inclined alternately in one direction and in the other so as to distribute the radiation uniformly over the entire surface of the nails. This operation is repeated twice more, so as to deposit three crosslinked coats on the nails.

A transparent nitrocellulose topcoat varnish coat is then applied to the surface of the deposit.

A glossy film with good staying power on the nail is obtained.

It is understood, in the context of the present invention, that the weight percentages given for a compound or a family of compounds are always expressed as weight of solids of the compound in question. Throughout the application, the term "comprises one" or "includes one" should be understood as meaning "comprising at least one" or "including at least one", unless otherwise specified.

Claims

1. Photo-crosslinkable cosmetic composition, free of reactive monomers with a molecular mass of less than 400 g/mol comprising one or more ethylenic double bonds, comprising, in a physiologically acceptable medium:

- at least one polymer comprising ethylenic double bonds, the mean number of ethylenic double bonds per polymer molecule being greater than 1, the said at least one polymer comprising at least one polyether polymer containing (meth)acrylate groups modified by reaction with an amino group, and

- at least one radical photoinitiator.

2. Photo-crosslinkable cosmetic composition according to Claim 1, in which the mean number of ethylenic double bonds per polymer molecule is greater than or equal to 2.

3. Photo-crosslinkable cosmetic composition according to Claim 1 or 2, additionally comprising at least one polyether polymer containing (meth)acrylate groups not modified by reaction with an amino group.

4. Photo-crosslinkable cosmetic composition according to Claim 1, 2 or 3, in which the polyether polymer(s) containing (meth)acrylate groups, modified or not, are obtained by esterification with the (meth)acrylic acid, on the one hand, or all of the end hydroxyl groups derived from (poly)hydroxylated, preferably polyhydroxylated, and (poly)alkoxylated, preferably polyalkoxylated, compounds.

5. Photo-crosslinkable cosmetic composition according to Claim 3 or 4, the polyether polymer(s) containing (meth)acrylate groups not modified by reaction with an amino group differing only from the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group NHR_aR_b by the presence of this amino group, Ra representing an alkyl substituted with a hydroxyl, alkoxy, tertiary amine or aryl, and Rb representing a hydrogen or an alkyl substituted with a hydroxyl, alkoxy, tertiary amine or aryl, it being possible for Ra and Rb to be linked together to form a ring.

6. Photo-crosslinkable cosmetic composition according to any one of the preceding claims, in which the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group correspond to formula (Γ) below:

in which formula (Γ):

^■ which may be identical or different, represent a single or double bond;

^■ ALK¹ and ALK², which may be identical or different, represent a (Ci-C6)aikyl group such as ethyl or propyl;

^■ x¹ and x², which may be identical or different, represent an integer greater than or equal to 1 , for instance between 1 and 1000 inclusive;

^■ R¹ and R², which may be identical or different, represent a hydrogen atom or a (Ci- C₆)alkyl group such as methyl; X, which may be identical or different, represent a CH₂ group when ^~~ is a double bond, or X represents an amino group CH₂NR_aR_b when is a single bond with R_a representing an alkyl optionally substituted with a hydroxyl, alkoxy, tertiary amine or aryl, and R_¾ representing a hydrogen or an alkyl optionally substituted with a hydroxide, alkoxy, tertiary amine or aryl. R_a and R_b may be linked together to form a ring;

* R' representing: i) a group of formula (Ι ) below:

in which formula (ΙΓ)'

- ALK represents a (Ci-C₆)alkyl group such as ethyl or propyl;

- x³ represents an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

- R represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

- X being as defined previously; ii) a group of formula (Π ) below:

in which formula (ΙΙΓ):

- ALK⁴ represents a (C|-C₆)alkyl group such as ethyl or propyl; - x⁴ represents an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

- R⁴ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

- X being as defined previously; iii) a group of formula (IV) below:

(*)— CH₂— O— ALK⁵ O— ALK⁶ (IV) in which formula (IV):

- ALK⁵ and ALK⁶, which may be identical or different, represent a (Ci-Cg)alkyl group such as ethyl or propyl; - X being as defined previously; or iv) a group of formula (V) below:

in which formula (V)-' - ALK⁷ and ALK⁸, which may be identical or different, represent a (Ci-C6)alkyl group such as ethyl or propyl;

7 ft

- x and x , which may be identical or different, represent an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

- R⁷ and R⁸, which may be identical or different, represent a hydrogen atom or a (Ci- C₆)alkyl group such as methyl;

- R'" being a hydrogen atom or a (C|-C₆)alkyl group such as ethyl, or an alkoxy group such as methoxy, or the group of formula (VF):

X

in which formula (VI'):

- ALK⁹ represents a (C] -C6)alkyl group such as ethyl or propyl;

- x⁹ represents an integer greater than or equal to 1 , for instance between 1 and 1000 inclusive;

- R⁹ represents a hydrogen atom or a (Ci-C6)alkyl group such as methyl;

- X being as defined previously;

- and mixtures thereof;

* R" representing a hydrogen atom or a (Ci-C₆)alkyl group such as ethyl, or an alkoxy group such as methoxy, or the group of formula (VIP):

X in which formula (VII'): - ALK represents a (Ci-C₆)alkyl group such as ethyl or propyl;

- x¹⁰ represents an integer greater than or equal to 1, for instance between 1 and 1000 inclusive;

- R¹⁰ represents a hydrogen atom or a (Ci-C₆)alkyl group such as methyl;

- and mixtures thereof.

7. Photo-crosslinkable cosmetic composition according to one of the preceding claims, in which the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group have a weight-average molar mass of greater than 450 and preferably between 500 and 3000.

8. Photo-crosslinkable cosmetic composition according to any one of the preceding Claims 3 to 7, in which the polyether polymer(s) containing (meth)acrylate groups not modified by reaction with an amino group are present in a total content of greater than or equal to 20% by weight relative to the total weight of the photo- crosslinkable cosmetic composition.

9. Photo-crosslinkable cosmetic composition according to any one of the preceding claims, in which the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group are preferably present in a total content of greater than or equal to 20% by weight relative to the total weight of the photo- crosslinkable cosmetic composition.

10. Photo-crosslinkable cosmetic composition according to any one of the preceding claims 3 to 9, in which the polyether polymer(s) containing (meth)acrylate groups not modified by reaction with an amino group and the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group are present in the composition in a respective total content such that the weight ratio of the polyether polymer(s) containing (meth)acrylate groups to the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group is between 0.3 and 3.

11. Photo-crosslinkable cosmetic composition according to any one of the preceding claims, in which the radical photoinitiator(s) are chosen from oc-hydroxy ketones, oc-amino ketones, aromatic ketones preferably associated with a hydrogen donor compound, aromatic oc-diketones, and acylphosphine oxides.

12. Photo-crosslinkable cosmetic composition according to any one of the preceding claims, in which the radical photoinitiator(s) are present in a total content of greater than or equal to 0.1% by weight relative to the total weight of the composition, and preferably between 1% and 5% by weight relative to the total weight of the composition.

13. Photo-crosslinkable cosmetic composition according to any one of the preceding claims, in which the radical photoinitiator(s) are present in a total content of greater than or equal to 0.1 % by weight relative to the total weight of the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group, and preferably between 0.5% and 3% by weight relative to the total weight of the polyether polymer(s) containing (meth)acrylate groups modified by reaction with an amino group.

14. Photo-crosslinkable cosmetic composition according to any one of the preceding claims, characterized in that it contains one or more solvents chosen from physiologically acceptable organic solvents such as ketones, alcohols, glycols, propylene glycol ethers, short-chain esters, alkanes, aromatic hydrocarbons and silicones, which are all liquid at room temperature, and mixtures thereof.

15. Photo-crosslinkable cosmetic composition according to any one of the preceding claims, also comprising at least one colouring agent chosen from pigments, and preferably from metal oxides, such as iron oxides.

16. Photo-crosslinkable cosmetic composition according to any one of the preceding claims, in which the said composition is a nail varnish.

17. Process for coating the nails and false nails, comprising at least: a step of applying a photo-crosslinkable cosmetic composition according to any one of Claims 1 to 16, so as to form a film on the nails or false nails, and

a step of exposing the deposited film to radiation of a suitable wavelength for a time that is sufficient to induce crosslinking of the said film.

18. Process according to Claim 17, comprising a subsequent step of applying an optionally photo-crosslinkable top coat over the photo-crosslinkable cosmetic composition.