PROCESS FOR DYEING KERATIN FIBRES USING A (CO)POLYMER BASED ON ACETOACETATE FUNCTIONS, A CROSSLINKING AGENT, A COLOURING AGENT AND A METAL COMPOUND

TECHNICAL FIELD OF THE INVENTION

The present invention concerns a particular process for dyeing keratin fibres, notably comprising the application to the keratin fibres of at least one (co)polymer based on acetoacetate functions, a crosslinking agent, a colouring agent and a metal compound.

BACKGROUND OF THE INVENTION

Cosmetic products often require the use of film-forming polymers to obtain a deposit of the product on keratin materials that has good cosmetic properties. In particular, it is necessary for the film-forming deposit to have good persistence, notably for the deposit not to transfer during contact with the fingers or clothing, and also good persistence on contact with water, notably rain or during showering or perspiration. Skin sebum may also damage the filmforming deposit.

In the field of dyeing keratin fibres, in particular human keratin fibres, it is already known practice to dye keratin fibres via various techniques notably using direct dyes for nonpermanent dyeing, or dye precursors for permanent dyeing.

Direct dyeing consists in dyeing keratin fibres with dye compositions containing direct dyes. These dyes are coloured and colouring molecules that have affinity for keratin fibres. They are applied to the keratin fibres for a time necessary to obtain the desired colouring, and are then rinsed out.

The standard dyes that are used are, in particular, dyes of the nitrobenzene, anthraquinone, nitropyridine, azo, xanthene, acridine, azine or triarylmethane type, or natural dyes.

Some of these dyes may be used under lightening conditions, which enables the production of colourings that are visible on dark hair.

Another non-permanent dyeing method consists in using pigments. Specifically, the use of pigment on the surface of keratin fibres generally makes it possible to obtain colourings that are visible on dark hair, since the surface pigment masks the natural colour of the fibre. The use of pigment for dyeing keratin fibres is described, for example, in patent application FR 2 741 530, which recommends using, for the temporary dyeing of keratin fibres, a composition comprising at least one dispersion of film-forming polymer particles including at least one acid function and at least one pigment dispersed in the continuous phase of said dispersion. Non-permanent colourings based on direct dyes and/or pigments may have the drawback of having poor resistance to water and/or shampoo washing and also to external agents such as sebum, perspiration, and mechanical actions such as brushing and/or rubbing. The colourings obtained may also give rise to staining and/or transfer, in particular when the fibres are wet. Moreover, the shampoo washing protocol may vary from one user to another, notably as regards the shampoo leave-on time, a longer leave-on time possibly being the cause of poorer persistence of the colouring with respect to shampoo washing.

Furthermore, non-permanent hair dye compositions may also lead to a hair feel that is uncosmetic and/or not natural, the hair thus dyed notably potentially lacking softness and/or suppleness and/or strand separation.

Moreover, the selectivity of the colouring obtained by this type of process can occasionally be substantial, i.e. differences in colouring that are sometimes substantial may be observed along the same length of keratin fibre, which generally includes zones that are differently sensitized from its root to its end.

There is thus a real need to develop a process for dyeing keratin fibres which makes it possible to obtain satisfactory colouring and which has better persistence with respect to shampoo washing, the persistence being independent of the shampoo washing protocol followed by the user and being notably observed for long shampoo leave-on times, i.e. at least one minute. Such a process must also make it possible to obtain colouring with little selectivity, i.e. small differences in colouring observed along the same length of keratin fibre, which generally includes zones that are differently sensitized from its root to its end.

The Applicant has discovered, surprisingly, that all or some of these objectives can be achieved by means of the process according to the present invention.

SUMMARY OF THE INVENTION

According to a first aspect, a subject of the present invention is a process for dyeing keratin fibres, comprising steps i) to iv) below: i) applying to the keratin fibres an aqueous dispersion (D) comprising: a) at least one (co)polymer having at least one acetoacetate unit of formula (I): in which:

• R ^b and R ^c , which may be identical or different, represent a hydrogen atom or a linear or branched (Ci-C4)alkyl group; preferably with R ^b and R ^c representing a hydrogen atom; and

• R ^d represents a linear or branched (Ci-C4)alkyl group, and preferably a methyl group;

- the symbol: represents the covalent bond established between the unit of formula (I) and the remainder of the (co)polymer; b) at least one polyvinylpyrrolidone; and c) water; ii) applying to the keratin fibres at least one crosslinking agent chosen from: a’) amine compounds chosen from polyamine compounds containing at least two primary amine and/or secondary amine groups, aminoalkoxysilanes, and mixtures thereof; and/or b’) organic or mineral, polymeric or non-polymeric, preferably organic or silicone-based, hydroxylated compounds chosen from polyhydroxylated compounds containing at least two hydroxyl groups; and/or c’) organic or mineral, polymeric or non-polymeric, preferably organic or silicone-based, thiol compounds chosen from polythiol compounds containing at least two thiol groups; and/or d’) (poly)carbonyl compounds such as terephthalaldehyde; and/or e’) (poly)acrylate compounds such as trimethylolpropane triacrylate; and iii) applying to the keratin fibres at least one colouring agent chosen from direct dyes, oxidation dyes, pigments and mixtures thereof; and iv) applying to the keratin fibres at least one metal compound chosen from: a) metal salts chosen from alkali metal salts, alkaline-earth metal salts such as magnesium salts, transition metal salts, post-transition metal salts such as aluminium or tin salts, metalloid salts such as boron salts, hydrates thereof and mixtures thereof; and/or

P) metal alkoxides of formulae (la), (lb), (Ic) and (Id) below and mixtures thereof:

M-(ORi) _n (la)

R-M-(ORi) _n -i (lb)

(RlO) _n -1-M-R”-M’-(ORl’)n- ₁ (Ic)

R-M(R’)-(ORi) _n -2 (Id) in which formulae (la), (lb), (Ic) and (Id):

- M and M’, which may be identical or different, represent an atom chosen from alkaline- earth metals, transition metals such as titanium or zirconium, metals of the lanthanide family, post-transition metals such as aluminium or tin and metalloids such as boron; preferably transition metals such as titanium or zirconium and post-transition metals such as aluminium;

- n and n’ respectively represent the valencies of the atoms represented by M and M’;

- Ri and R’i, which may be identical or different, represent a linear or branched, saturated or unsaturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 1 to 6 carbon atoms, said hydrocarbon-based group being optionally interrupted with 1 to 20 heteroatoms chosen from O, N, S and P, notably O or N; and/or said hydrocarbonbased group being optionally substituted with one or more hydroxyl or carbonyl groups;

- R and R’, which may be identical or different, represent a hydrogen atom or a linear, branched or cyclic, saturated or unsaturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 2 to 20 carbon atoms, optionally interrupted with 1 to 20 heteroatoms chosen from O, N, S and/or P, notably O or N, and/or said hydrocarbon-based group being optionally substituted with one or more hydroxyl or carbonyl groups;

- R” represents -O-, -NR2-, -S- or a linear, cyclic or branched, saturated or unsaturated divalent hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 2 to 20 carbon atoms, optionally interrupted with 1 to 20 heteroatoms chosen from O, N, S and P, notably O or N, with R ₂ representing a linear, cyclic or branched, saturated or unsaturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 2 to 20 carbon atoms; it being understood that steps i) to iv) are performed separately or at least two of the steps i) to iv) are performed simultaneously.

According to a second aspect, a subject of the present invention is a composition (A0) comprising:

- an aqueous dispersion (D) as defined previously; and

- one or more crosslinking agents as defined previously; and

- one or more colouring agents as defined previously; and

- one or more metal compounds as defined previously.

According to a third aspect, a subject of the present invention is a kit or device containing several separate compartments, comprising:

■ in a first compartment: a composition (A1) comprising:

- an aqueous dispersion (D) as defined previously; and 5 - optionally one or more colouring agents as defined previously; and - optionally one or more metal compounds as defined previously; and ▪ in a second compartment separate from the first: a composition (B1) comprising: - one or more crosslinking agents as defined previously; and 5 - optionally one or more colouring agents as defined previously; and - optionally one or more metal compounds as defined previously; it being understood that: - at least one of the compositions (A1) or (B1), preferably composition (A1), comprises one or more colouring agents as defined previously; and 10 - at least one of the compositions (A1) or (B1), preferably composition (A1) comprises one or more metal compounds as defined previously; or ▪ in a first compartment: a composition (A2) comprising: - an aqueous dispersion (D) as defined previously; and 15 - optionally one or more colouring agents as defined previously; and ▪ in a second compartment separate from the first: a composition (B2) comprising: - one or more crosslinking agents as defined previously; and - optionally one or more colouring agents as defined previously; and ▪ in a third compartment separate from the first and the second: a composition (C) 20 comprising: - one or more metal compounds as defined previously; and - optionally one or more colouring agents as defined previously; it being understood that: - at least one of the compositions (A2), (B2) or (C), preferably at least one of the 25 compositions (A2) or (C), more preferentially the composition (A2) comprises one or more colouring agents as defined previously. DETAILED DESCRIPTION OF THE INVENTION For the purposes of the present invention and unless otherwise indicated: 30 ▪ the term “keratin fibres” means fibres of human or animal origin, such as head hair, bodily hairs, the eyelashes, the eyebrows, wool, angora, cashmere or fur. According to the present invention, the keratin fibres are preferably human keratin fibres, more particularly head hair; ▪ the term “alkyl group” means a linear or branched, saturated hydrocarbon-based group, preferably of C ₁ -C ₈ , more preferentially C ₁ -C ₆ and even more preferentially C ₁ -C ₄ , such as 35 methyl, ethyl, propyl, isopropyl, n-butyl and t-butyl; 6 ▪ the term “alkoxy group” means an alkyl-oxy group with alkyl as defined previously, preferably C ₁ -C ₄ alkoxy, such as methoxy, ethoxy, isopropyloxy or butoxy; ▪ the term “optionally substituted” attributed to the alkyl group implies that said alkyl group may be substituted with one or more groups chosen from the following groups: i) hydroxyl, 5 ii) C ₁ -C ₄ alkoxy, iii) acylamino, iv) amino optionally substituted with one or two identical or different C ₁ -C ₄ alkyl groups, said alkyl radicals possibly forming, with the nitrogen atom that bears them, a 5- to 7-membered heterocycle, optionally comprising another nitrogen or non- nitrogen heteroatom; ▪ when the alkoxy group is optionally substituted, this implies that the alkyl group is 10 optionally substituted as defined above; ▪ the term “alkylene group” means a linear or branched divalent saturated hydrocarbon- based group preferably of C ₁ -C ₈ , more preferentially C ₁ -C ₆ and even more preferentially C ₁ - C ₄ such as methylene, ethylene or propylene; ▪ the term “cycloalkyl group” means a cyclic saturated hydrocarbon-based group 15 comprising from 1 to 3 rings, preferably 2 rings, and comprising from 3 to 13 carbon atoms, preferably between 5 and 10 carbon atoms, such as cyclopentyl, cyclohexyl, cycloheptyl, norbornyl, or isobornyl, the cycloalkyl group possibly being substituted with one or more (C ₁ - C ₄ )alkyl groups such as methyl; preferably, the cycloalkyl group is an isobornyl group; ▪ the term “cyclic group” means a cyclic, saturated or unsaturated, aromatic or non- 20 aromatic hydrocarbon-based group comprising from 1 to 3 rings, preferably 1 ring, and comprising from 3 to 10 carbon atoms, such as cyclohexyl or phenyl; ▪ the term “heterocyclic group” means a cyclic, saturated or unsaturated, aromatic or non- aromatic hydrocarbon-based group comprising from 1 to 3 rings, preferably 1 ring, and comprising from 3 to 10 carbon atoms and from 1 to 5 heteroatoms chosen from O, S and 25 N, such as morpholinyl, piperazinyl, piperidyl, furyl, pyridyl or indolyl; ▪ the term “aryl group” means a monocyclic or fused or non-fused bicyclic, unsaturated cyclic aromatic group comprising from 6 to 12 carbon atoms; preferably, the aryl group comprises 1 ring and contains 6 carbon atoms, such as phenyl; ▪ the term “aryloxy group” means an aryl-oxy, i.e. aryl-O-, group, with aryl as defined 30 previously, preferably phenoxy; ▪ the term “aryl(C1-C4)alkoxy group” means an aryl(C1-C4)alkyl-O- group, preferably benzoxy; ▪ the term “heteroaryl group” means a monocyclic or fused or non-fused polycyclic, 5- to 22-membered group, comprising from 1 to 6 heteroatoms chosen from nitrogen, oxygen, sulfur and selenium atoms, and at least one ring of which is aromatic; preferentially, a heteroaryl group is chosen from acridinyl, benzimidazolyl, benzobistriazolyl, benzopyrazolyl, benzopyridazinyl, benzoquinolyl, benzothiazolyl, benzotriazolyl, benzoxazolyl, pyridyl, tetrazolyl, dihydrothiazolyl, imidazopyridyl, imidazolyl, indolyl, isoquinolyl, naphthoimidazolyl, naphthooxazolyl, naphthopyrazolyl, oxadiazolyl, oxazolyl, oxazolopyridyl, phenazinyl, phenoxazolyl, pyrazinyl, pyrazolyl, pyrilyl, pyrazoyltriazyl, pyridyl, pyridinoimidazolyl, pyrrolyl, quinolyl, tetrazolyl, thiadiazolyl, thiazolyl, thiazolopyridyl, thiazoylimidazolyl, thiopyrylyl, triazolyl and xanthylyl;

■ the “aryl” or “heteroaryl” groups or the aryl or heteroaryl part of a group may be substituted with at least one substituent borne by a carbon atom, chosen from:

- a Ci-Cs alkyl group optionally substituted with one or more groups chosen from hydroxyl, C1-C2 alkoxy, (poly)hydroxy(C2-C4)alkoxy, acylamino, amino substituted with two identical or different C1-C4 alkyl groups, optionally bearing at least one hydroxyl group, or the two groups possibly forming, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5- to 7-membered and preferably 5- or 6-membered heterocycle optionally comprising another nitrogen or non-nitrogen heteroatom;

- a halogen atom;

- a C1-C2 alkoxy group;

- a 5- or 6-membered heterocycloalkyl group;

- an acylamino group (-NR-COR’) in which the group R is a hydrogen atom, a C1-C4 alkyl group and the group R’ is a C1-C2 alkyl group; a carbamoyl group ((R)2N-CO-) in which the groups R, which may be identical or different, represent a hydrogen atom, a C1-C4 alkyl group; an alkylsulfonylamino group (R’SC>2-NR-) in which the group R represents a hydrogen atom or a C1-C4 alkyl group and the group R’ represents a C1-C4 alkyl group or a phenyl group; an aminosulfonyl group ((R)2N-SO2-) in which the groups R, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl group;

- a carboxylic group in acid or salified form (preferably with an alkali metal or a substituted or unsubstituted ammonium);

- a cyano group;

- a polyhaloalkyl group, preferentially trifluoromethyl;

■ the cyclic or heterocyclic part of a non-aromatic group may be substituted with at least one substituent chosen from the following groups:

- C1-C4 alkoxy;

- C1-C4 alkyl;

- alkylcarbonylamino (RCO-NR’-) in which the radical R’ is a hydrogen atom or a C1-C4 alkyl group and the group R is a C1-C2 alkyl group;

- alkylcarbonyloxy (RCO-O-) in which the radical R is a C1-C4 alkyl group or an amino group optionally substituted with one or two identical or different C1-C4 alkyl groups, said alkyl groups possibly forming, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle optionally comprising at least one other nitrogen or non-nitrogen heteroatom;

- alkoxycarbonyl (RG-CO-) in which the group R is a C1-C4 alkoxy group, G is an oxygen atom or an amino group optionally substituted with a C1-C4 alkyl group itself, said alkyl group possibly forming, with the nitrogen atom to which they are attached, a saturated or unsaturated, optionally substituted 5- to 7-membered heterocycle, optionally comprising at least one other nitrogen or non-nitrogen heteroatom;

■ a cyclic or heterocyclic group, or a non-aromatic part of an aryl or heteroaryl group, may also contain one or more oxo groups;

■ a hydrocarbon-based chain is unsaturated when it includes one or more double bonds and/or one or more triple bonds, preferably one or more double bonds.

Unless otherwise indicated, when compounds are mentioned in the present patent application, this also includes the optical isomers thereof, the geometrical isomers thereof, the tautomers thereof, the salts thereof or the solvates thereof, alone or as a mixture.

The terms “at least one” and “one or more” are synonymous and may be used interchangeably.

Process for dveina keratin fibres

According to a first aspect, a subject of the present invention is a process for dyeing keratin fibres as defined previously.

Steps i) to iv) may be performed in the order i) to iv) or in any order.

The process may also comprise one or more additional steps between steps i) to iv).

When all of the steps i) to iv) are performed simultaneously, the process involves applying to the keratin fibres a single composition comprising the aqueous dispersion (D), the crosslinking agent(s) ii), the colouring agent(s) iii) and the metal compound(s) iv).

The Applicant has found, surprisingly, that the process according to the invention notably makes it possible to obtain on keratin fibres coloured coatings which have a visible colouring on all types of fibres, notably on dark hair, the colouring being persistent with respect to shampoo washing independently of the shampoo washing protocol followed by the user, the persistence being notably observed for long shampoo leave-on times, i.e. at least one minute. Furthermore, the process makes it possible in particular to obtain a smooth and uniform deposit and the keratin fibre strands remain perfectly separated and could be styled without any problem. Finally, the colouring obtained via the process according to the invention is characterized by low selectivity.

The term “keratin fibres with separated strands” means keratin fibres, notably hair, which, after performing the process of the invention and drying, are not stuck together (or are all separate from each other) and therefore do not form clumps of fibres, since the coating is formed around virtually every fibre.

Aqueous dispersion (D)

The aqueous dispersion (D) comprises a) at least one (co)polymer having at least one acetoacetate unit of formula (I) as defined previously, b) at least one polyvinylpyrrolidone and c) water.

(Co)polymers bearing at least one acetoacetate unit

For the purposes of the invention, the term “(co)polymers” means that the polymer containing acetoacetate unit(s) according to the invention may be a homopolymer or a copolymer.

Thus, the (co)polymers bearing one or more acetoacetate units which are under consideration according to the invention are obtained by polymerization of monomers M, which may be identical or different, including at least monomers containing acetoacetate unit(s).

Thus, according to a first variant, the (co)polymers bearing acetoacetate unit(s) according to the invention are homopolymers and are thus obtained by polymerization of identical monomers bearing acetoacetate units.

According to a second variant, the (co)polymers bearing acetoacetate unit(s) according to the invention are copolymers and these copolymers may be obtained either by copolymerization of monomers bearing different acetoacetate units or by copolymerization of monomers bearing acetoacetate units, which may be identical or different, with monomers “M”’ not bearing acetoacetate units and which may be identical or different.

Preferably, the (co)polymers bearing acetoacetate unit(s) according to the invention are copolymers obtained by polymerization of one or more monomers bearing acetoacetate 10 unit(s), which may be identical or different, preferably identical, with one or more monomers M’, which may be identical or different, and which do not bear an acetoacetate unit. Monomers bearing acetoacetate unit(s) 5 The monomer(s) bearing acetoacetate unit(s) are preferably chosen from the monomers of the following formula (II): In which: - R ^a represents a hydrogen atom or a linear or branched (C ₁ -C ₄ )alkyl group, and preferably 10 is a methyl group, - ^Rb _{and R} ^c _{, which may be identical or different, represent a hydrogen atom or a linear or} branched (C ₁ -C ₄ )alkyl group, and preferably R ^b and R ^c represent a hydrogen atom, - R ^d represents a linear or branched (C ₁ -C ₄ )alkyl group, and preferably is a methyl group, and 15 - L represents a linear or branched (C ₁ -C ₃₀ )alkylene, or cycloalkylene, group, particularly a (C ₁ -C ₂₀ )alkylene and preferably (C ₂ -C ₆ )alkylene group, such as ethylene, and - n is equal to 0 or 1, and preferably 1. Monomers chosen from acetoacetoxyéthyl methacrylate, linear or branched C ₁ -C ₂₀ allyl acetoacetates, and mixtures thereof, and more particularly monomers comprising at least 20 acetoacetoxyethyl methacrylate, are thus most particularly suitable for use in the invention, and said polymerization being optionally performed in the presence of a radical initiator, notably of the peroxide, persulfate or azo type. Thus, more preferentially, the (co)polymers bearing an acetoacetate unit according to the invention are obtained by homo- or co-polymerization of acetoacetoxyethyl methacrylate. 25 According to a particular embodiment, the (co)polymers bearing acetoacetate units according to the invention are homopolymers obtained by polymerization of monomers bearing identical acetoacetate units. According to this embodiment, the (co)polymer bearing an acetoacetate unit according to the invention is preferably a homopolymer obtained by polymerization of monomers of 30 formula (II), and most particularly of acetoacetoxyethyl methacrylate. 11 According to another particular embodiment, the (co)polymers bearing acetoacetate unit(s) according to the invention are copolymers obtained by polymerization of: a) from 0.1% to 99.9% by weight of identical or different monomers bearing acetoacetate units, relative to the total weight of monomers, and 5 b) from 0.1% to 99.9% by weight of identical or different monomers M’, free of acetoacetate units, relative to the total weight of monomers. 10 Monomers M’ free of acetoacetate units The monomers M’ free of acetoacetate units may be chosen more particularly from: a) the (C ₁ -C ₂₀ )alkyl (alkyl)(meth)acrylate monomers of formula (F1): 15 in which : - R represents a hydrogen atom or a linear or branched (C ₁ -C ₄ )alkyl group, preferably methyl, and - R ₁ represents a linear or branched C ₁ -C ₂₀ alkyl group, in particular chosen from methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n- 20 butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, and most particularly methyl (meth)acrylate such as methyl acrylate, 2- ethylhexyl (meth)acrylate such as 2-ethylhexyl acrylate, n-butyl (meth)acrylate such as n- butyl methacrylate, and stearyl (meth)acrylate such as stearyl methacrylate; b) the (alkyl)(meth)acrylate monomers bearing a cyclic group of formula (F2): 25 in which: - R represents a hydrogen atom or a linear or branched (C ₁ -C ₄ )alkyl group, and - R ₂ represents a cyclic alkyl group containing from 8 to 30 carbon atoms, and most particularly isobornyl (meth)acrylate such as isobornyl acrylate; and 30 c) silicone (meth)acrylate macromonomers, in particular those whose homopolymers have a glass transition temperature (T _g ) of less than or equal to 25°C, notably ranging from - 100°C to 25°C, preferably ranging from -90°C to 0°C. The term “silicone macromonomer” means a silicone macromolecule bearing an end group that enables it to act as a monomer. The silicone macromonomers will provide a single monomer unit to a chain of the finished macromolecule.

As regards the silicone (meth)acrylate macromonomers, they may in particular be polydimethylsiloxanes bearing a monoacryloyloxy or monomethacryloyloxy end group, and notably those of formula (F3): in which:

- Rs denotes a hydrogen atom or a methyl group, preferably methyl;

- R9 denotes a linear or branched, preferably linear, divalent hydrocarbon-based group containing from 1 to 10 carbon atoms and optionally containing one or two -O- ether bonds; preferably ethylene, propylene or butylene;

- R10 denotes a linear or branched alkyl group containing from 1 to 10 carbon atoms, notably from 2 to 8 carbon atoms; preferably methyl, ethyl, propyl, butyl or pentyl; and

- n denotes an integer ranging from 1 to 300, more preferentially ranging from 3 to 200. These may notably be polydimethylsiloxane methacrylates and in particular the products sold under the name MCR-M17 by Gelest Inc., or x-22-2475 and x-22-2426 by Shin-Etsu.

The macromonomers that are most particularly suitable for use in the invention have a weight-average molecular mass (Mw) ranging from 200 to 100 000, preferentially from 400 to 20 000.

By way of non-limiting illustration, the copolymers bearing acetoacetate units that are suitable for use in the invention may be chosen most particularly from:

- copolymers obtained by polymerization of at least one monomer bearing acetoacetate unit(s), ACAC, in particular acetoacetoxyethyl methacrylate, with one or more monomers of formula (F1), which may be identical or different, notably in a mass ratio of ACAC monomers/(F1) monomers ranging from 99/1 to 1/99, notably from 95/5 to 5/95, more particularly from 0.05 to 19;

- copolymers obtained by polymerization of at least one monomer bearing acetoacetate unit(s), ACAC, in particular acetoacetoxyethyl methacrylate, with one or more monomers of formula (F2), in particular isobornyl acrylate, notably in a mass ratio of ACAC monomers/monomers (F2) ranging from 99/1 to 1/99, notably from 95/5 to 5/95; - copolymers obtained by polymerization of at least one monomer bearing acetoacetate unit(s), ACAC, in particular acetoacetoxyethyl methacrylate, with one or more silicone macromonomers, notably of formula (F3), in particular with a mass ratio of ACAC monomers/silicone macromonomers, notably of formula (F3), ranging from 99/1 to 1/99, notably from 95/5 to 5/95;

- copolymers obtained by polymerization of at least one monomer bearing acetoacetate unit(s), ACAC, in particular acetoacetoxyethyl methacrylate, with at least one monomer of formula (F1) and at least one monomer of formula (F2) notably in a monomer ACAC/monomer (F1) + (F2) mass ratio ranging from 99/1 to 1/99 and a monomer (F1)/monomer (F2) mass ratio ranging from 0.1/99.9 to 99.9/0.1 , notably from 1/99 to 99/1 ;

- copolymers obtained by polymerization of at least one monomer bearing acetoacetate unit(s), ACAC, in particular acetoacetoxyethyl methacrylate, with at least one monomer of formula (F1) and at least one silicone (meth)acrylate macromonomer, in particular of formula (F3), notably in a mass ratio of ACAC monomers/monomers (F1) + silicone macromonomers, in particular of formula (F3), of from 99/1 to 1/99 and a monomer (F1)/silicone macromonomer mass ratio notably of formula (F3) ranging from 99/1 to 1/99;

- copolymers obtained by polymerization of at least one monomer bearing acetoacetate unit(s), ACAC, in particular acetoacetoxyethyl methacrylate, with at least one monomer of formula (F2) and at least one silicone (meth)acrylate macromonomer, notably of formula (F3) in particular a PDMS methacrylate, notably in a mass ratio of ACAC monomers/monomers (F2) + silicone macromonomers notably of formula (F3) ranging from 99/1 to 1/99 and a mass ratio of monomers (F2)/silicone macromonomers notably of formula (F3) ranging from 99/1 to 1/99;

- copolymers obtained by polymerization of at least one monomer bearing acetoacetate unit(s), ACAC, in particular acetoacetoxyethyl methacrylate, with at least one monomer of formula (F1), at least one monomer of formula (F2) and at least one silicone (meth)acrylate macromonomer notably of formula (F3) with a mass ratio of ACAC monomers/monomers (F1) + (F2) + silicone macromonomers ranging from 1/99 to 99/1 and in particular a mass percentage of monomers (F1)/(monomers (F1) + (F2) + silicone macromonomers) x 100 ranging from 0.5% to 99%, in particular 2% to 90% and preferentially 5% to 15%, and/or a monomer (F1)/macromonomer (F2) mass ratio ranging from 0.5/99.5 to 99.5/0.5, in particular from 95/5 to 5/95, more particularly from 1/2 to 1/20, and/or a monomer (F1)/silicone macromonomer (F3) mass ratio ranging from 0.5/20 to 99/0.5, in particular from 1/20 to 80/0.5, and more particularly from 1 to 2. According to a particular embodiment, the acetoacetate unit (co)polymers according to the invention represent from 80% to 99.5% by weight of dry matter of the aqueous dispersion (D).

Polyvinylpyrrolidone

In general, the polyvinylpyrrolidones, PVPs, that are suitable for use in the invention have a mass of from 10 000 to 600 000 Da, notably from 20 000 to 500 000 Da.

It may notably be a polyvinylpyrrolidone such as those sold under the references PVP K 30L and PVP K 90 by the company Ashland, and those available from Sigma-Aldrich.

An aqueous dispersion (D) according to the invention may contain a single type of PVP or several PVPs which differ in terms of mass.

In a particular embodiment, an aqueous dispersion (D) in accordance with the invention contains from 0.2% to 20% by weight, notably from 0.3% to 19% by weight, and more particularly from 0.5% to 15% by weight of polyvinylpyrrolidone(s), relative to the weight of acetoacetate (co)polymer(s) present in the aqueous dispersion (D).

In a particular embodiment, an aqueous dispersion (D) in accordance with the invention contains from 0.1% to 20% by weight, notably from 0.3% to 19% by weight, in particular from 0.5% to 15% by weight, and notably from 1.5% to 15% by weight of polyvinylpyrrolidone(s), relative to the total dry weight of the aqueous dispersion (D).

The aqueous dispersion (D) according to the invention also contains water.

In a particular embodiment, an aqueous dispersion (D) in accordance with the invention contains from 80% to 35% by weight of water, preferably from 70% to 40% by weight of water, notably from 65% to 50% of water, relative to the total weight of the aqueous dispersion (D).

Process for preparing an aqueous dispersion according to the invention

An aqueous dispersion (D) in accordance with the invention may be obtained by conventional or non-conventional, and preferably conventional, radical polymerization of monomers bearing acetoacetate functions and optionally of one or more monomers M', in the presence of at least one polyvinylpyrrolidone.

Thus, the present invention also proposes a process for preparing an aqueous dispersion (D) in accordance with the invention, comprising at least one step consisting in polymerizing in an aqueous medium at least monomers bearing acetoacetate unit(s), which may be identical or different, and in particular of formula (II) as defined above, in the presence of at least one polyvinylpyrrolidone. More precisely, a solution of the polyvinylpyrrolidone is prepared in a synthetic medium containing water and optionally at least one water-miscible solvent such as a C1-C4 alcohol such as ethanol, for example an aqueous-alcoholic medium, and polymerization of the monomers bearing an acetoacetate function and optionally of monomers M' is then performed in this medium, notably in the presence of an initiator.

Preferably, the monomers to be (co)polymerized can be incorporated into this synthetic medium, as such or in a form previously dissolved in a water-miscible organic solvent, notably water-miscible solvent(s) such as ethanol which may already be present in this synthetic medium.

The monomers to be polymerized can be introduced into the synthetic medium either as a whole before the start of the polymerization reaction or gradually or sequentially, as the polymerization proceeds.

This polymerization is performed in the presence of a radical initiator, notably of the peroxide, persulfate or azo type.

In particular, this radical initiator may be chosen from tert-butyl peroxy-2-ethylhexanoate, such as for example Trigonox 21 S sold by AkzoNobel, 2,5-dimethyl-2,5-bis(2- ethylhexanoylperoxy)hexane, such as for example Trigonox 141 sold by AkzoNobel, tertbutyl peroxypivalate, such as for example Trigonox 25C75 sold by AkzoNobel, azobisisobutyronitrile (AIBN) and 2,2’-azobis(2-amidinopropane) dihydrochloride (V50), hydrogen peroxide, persulfates such as potassium persulfate, ammonium persulfate and sodium persulfate. Preferably, the radical initiator is potassium persulfate, such as potassium persulfate sold by Sigma-Aldrich.

This polymerization is generally performed at a temperature ranging from 70°C to 110°C.

More particularly, the present invention proposes a process for preparing an aqueous dispersion (D) as defined previously, comprising at least the steps of: a) providing a solution comprising water and preferably one or more water-miscible solvents notably chosen from C1-C4 alcohols and in particular ethanol and at least one polyvinylpyrrolidone, b) adding to said solution a) at least one monomer bearing an acetoacetate function and optionally at least one monomer M’ as defined previously, c) promoting the (co)polymerization of said monomer bearing acetoacetate units, and d) optionally, at the end of the (co)polymerization c), removing the water-miscible solvent(s) if present; said process preferably using at least one radical initiator, notably as defined previously and it being understood that step a) may be followed by a heating step, notably at a temperature of 50°C to 90°C.

By way of non-limiting illustration of aqueous dispersions in accordance with the invention, mention may notably be made of the dispersions obtained by polymerization of:

- acetoacetoxyethyl methacrylate in the presence of polyvinylpyrrolidone, preferably in a polyvinylpyrolidone/acetoacetoxyethyl methacrylate mass ratio of 10/90;

- methyl acrylate and acetoacetoxyethyl methacrylate in the presence of polyvinylpyrrolidone, preferably in a polyvinylpyrolidone/methyl acrylate/acetoacetoxyethyl methacrylate mass ratio of 2/88/10;

- isobornyl acrylate, 2-ethylhexyl acrylate and acetoacetoxyethyl methacrylate in the presence of polyvinylpyrrolidone, preferably in a polyvinylpyrolidone/isobornyl acrylate/2- ethylhexyl acrylate/acetoacetoxyethyl methacrylate mass ratio of 2/59/29/10;

- butyl methacrylate, PDMS 12K methacrylate and acetoacetoxyethyl methacrylate in the presence of polyvinylpyrrolidone, preferably in a polyvinylpyrolidone/butyl methacrylate/PDMS 12K metacrylate/acetoacetoxyethyl methacrylate mass ratio of 2/83/5/10; or

- methyl acrylate, stearyl methacrylate and acetoacetoxyethyl methacrylate in the presence of polyvinylpyrrolidone, preferably in a polyvinylpyrolidone/methyl methacrylate/stearyl methacrylate/acetoacetoxyethyl methacrylate mass ratio of 2/68/20/10.

The dyeing process according to the present invention comprises step ii) of applying to the keratin fibres one or more crosslinking agents chosen from: a’) amine compounds chosen from polyamine compounds containing at least two primary amine and/or secondary amine groups, aminoalkoxysilanes, and mixtures thereof; and/or b’) organic or mineral, polymeric or non-polymeric, preferably organic or silicone-based, hydroxylated compounds chosen from polyhydroxylated compounds containing at least two hydroxyl groups; and/or c’) organic or mineral, polymeric or non-polymeric, preferably organic or silicone-based, thiol compounds chosen from polythiol compounds containing at least two thiol groups; and/or d’) (poly)carbonyl compounds such as terephthalaldehyde; and/or e’) (poly)acrylate compounds such as trimethylolpropane triacrylate. For the purposes of the invention, the term “crosslinking agent” denotes a compound that is capable of establishing at least one covalent bond with at least one acetoacetate function of the (co)polymer a) and thus of crosslinking this copolymer.

For the purposes of the present invention, it is understood that the terms “crosslinking agent” and “crosslinker” are equivalent.

Amine compounds

The crosslinking agent(s) may be chosen from a’) amine compounds chosen from polyamine compounds containing at least two primary and/or secondary amine groups, aminoalkoxysilanes, and mixtures thereof.

Preferably, the amino compounds are chosen from diamine compounds, triamine compounds, aminoalkoxysilanes, and mixtures thereof.

Polyamine compounds

The polyamine compounds may be polymeric or non-polymeric.

The term “non-polymeric compound(s)” refers to one or more compounds which are not directly obtained via a monomer polymerization reaction.

According to a particular embodiment of the invention, the polyamine compounds particularly comprise from 2 to 20 carbon atoms; the polyamine compounds are notably non-polymeric.

Polyamine compounds that may notably be mentioned include N-methyl-1 ,3- diaminopropane, N-propyl-1 ,3-diaminopropane, N-isopropyl-1,3-diaminopropane, N- cyclohexyl-1 ,3-diaminopropane, 2-(3-aminopropylamino)ethanol, 3-(2- aminoethyl)aminopropylamine, bis(3-aminopropyl)amine, methylbis(3-aminopropyl)amine, N-(3-aminopropyl)-1 ,4-diaminobutane, N,N-dimethyldipropylenetriamine, 1 ,2-bis(3- aminopropylamino)ethane, N,N’-bis(3-aminopropyl)-1 ,3-propanediamine, ethylenediamine, 1 ,3-propylenediamine, 1 ,4-butylenediamine, lysine, cystamine, xylenediamine, tris(2- aminoethyl)amine and spermidine.

According to another particular embodiment of the invention, the polyamine compounds are polymeric. 18 The polyamine compounds may have a weight-average molecular weight ranging from 500 to 1000000, preferably ranging from 500 to 500000 and more preferentially from 500 to 100000. 5 The polyamine compounds may be chosen from: ▪ poly((C ₂ -C ₅ )alkyleneimines), and in particular polyethyleneimines and polypropyleneimines, notably poly(ethyleneimine)s (for example the product sold under the reference 46,852-3 by the company Aldrich Chemical); ▪ poly(allylamines) (for example the poly(allylamine) sold under the reference 47,913-6 by 10 the company Aldrich Chemical); ▪ polyvinylamines and copolymers thereof, notably with vinylamides; mention may notably be made of vinylamine/vinylformamide copolymers, such as those sold under the name Lupamin® 9030 by the company BASF; ▪ polyamino acids containing NH ₂ groups such as polylysine, for example the product sold 15 by the company JNC Corporation (formerly Chisso); ▪ protein hydrolysates, such as those sold under the name Soyaline® by the company Solabia; ▪ aminodextran, such as the product sold by the company CarboMer Inc; ▪ amino polyvinyl alcohol, such as the product sold by the company CarboMer Inc; 20 ▪ copolymers based on acrylamidopropylamine; ▪ chitosans; and ▪ polydi(C ₁ -C ₄ )alkylsiloxanes, in particular polydimethylsiloxanes, comprising amine groups at the chain end or on side chains, in particular terminal or side amino(C ₁ -C ₆ )alkyl groups such as aminopropyl, more particularly those of formula (IVb) or (IVc) or (IVd): 25 in which formula (IVb) R ^a and R ^b , which may be identical or different, preferably identical, represent a group from among: (C ₁ -C ₄ )alkyl such as methyl, (C ₁ -C ₄ )alkoxy such as methoxy, aryl such as phenyl, aryloxy such as phenoxy, aryl(C ₁ -C ₄ )alkyl such as benzyl, or aryl(C ₁ - C ₄ )alkoxy such as benzoxy, preferably (C ₁ -C ₄ )alkyl such as methyl, R ^c and R’ ^c , which may 30 be identical or different, preferably identical, represent a hydrogen atom, a (C ₁ -C ₄ )alkyl 19 group, an amino(C ₁ -C ₄ )alkyl group or a (C ₁ -C ₄ )alkylamino(C ₁ -C ₄ )alkyl group, preferably a hydrogen atom or an amino(C ₁ -C ₄ )alkyl group such as aminoethyl; X represents a covalent bond, an oxygen atom, preferably a covalent bond, ALK and ALK’, which may be identical or different, preferably identical, represent a (C ₁ -C ₆ )alkylene group, preferably (C ₁ - 5 C ₄ )alkylene group such as propylene; n representing an integer greater than 2 and more particularly the value of n is such that the weight-average molecular weight of the silicone is between 500 and 55000. Preferentially, the polydi(C ₁ -C ₄ )alkylsiloxanes of formula (IVb) are of formula (IV’b) or (IV”b) below: 10 in which formula (IVb’) the value of n is such that the weight-average molecular weight of the silicone is between 500 and 55000. As examples of aminosilicones (IVb) or (IV’b), mention may be made of those sold under the names DMS-A11, DMS-A12, DMS-A15, 15 DMS-A21, DMS-A31, DMS-A32 and DMS-A35 by the company Gelest; formula (IV’’b) with R ^c , R’ ^c , ALK, ALK’ and n as defined previously for (IVb). Preferably, ALK and ALK’ are identical and represent a (C ₁ -C ₄ )alkylene group such as propylene, R ^c and R’ ^c are identical and represent an amino(C ₁ -C ₄ )alkyl group such as aminoethyl. Mention may be made particularly of Dimethoxysilyl Ethylenediaminopropyl Dimethicone 20 (RN: 71750-80-6), under the trade name GP-RA-157, sold by Genesee Polymers. 20 in which formula (IVc) R ^a , R ^b and R ^d , which may be identical or different, preferably identical, represent a group from among: (C ₁ -C ₄ )alkyl such as methyl, (C ₁ -C ₄ )alkoxy such as methoxy, aryl such as phenyl, aryloxy such as phenoxy, aryl(C ₁ -C ₄ )alkyl such as benzyl, or aryl(C ₁ - 5 C ₄ )alkoxy such as benzoxy, preferably (C ₁ -C ₄ )alkyl such as methyl, R ^d may also represent a (C ₁ -C ₆ )alkyl group substituted with a (C ₁ -C ₄ )alkylamino or amino group, R ^c represents a hydrogen atom or a (C ₁ -C ₄ )alkyl group, preferably a hydrogen atom; ALK represents a (C ₁ - C ₆ )alkylene group, preferably (C ₁ -C ₄ )alkylene such as propylene; n and m, which may be identical or different, represent an integer greater than 2 and more particularly the values of 10 m and n are such that the weight-average molecular weight of the silicone is between 1000 and 55000. Preferentially, the polydi(C ₁ -C ₄ )alkylsiloxanes of formula (IVc) have the formula (IV’c) below: 15 in which formula (IV’c) the values of n and m are such that the weight-average molecular weight of the silicone is between 1000 and 55000. As examples of silicones (IVc), mention may be made of those sold under the names AMS-132, AMS-152, AMS-162, AMS-163, AMS-191 and AMS-1203 by the company Gelest; in which formula (IVd) R ^a and R ^b , which may be identical or different, preferably identical, represent a group from among: (C ₁ -C ₄ )alkyl such as methyl, (C ₁ -C ₄ )alkoxy such as methoxy, aryl such as phenyl, aryloxy such as phenoxy, aryl(C ₁ -C ₄ )alkyl such as benzyl, or aryl(C ₁ - C ₄ )alkoxy such as benzoxy, preferably (C ₁ -C ₄ )alkyl such as methyl, and R ^d represents a (C ₁ -C ₆ )alkyl group optionally substituted with a (C ₁ -C ₄ )alkylamino or amino group, preferably (C ₁ -C ₄ )alkyl such as isobutyl, tert-butyl or n-butyl, R ^c represents a hydrogen atom or a (C ₁ -C ₄ )alkyl group, preferably a hydrogen atom; ALK represents a (C ₁ -C ₆ )alkylene group, preferably (C ₁ -C ₄ )alkylene such as propylene, n representing an integer greater than 2 and more particularly the value of n is such that the weight-average molecular weight of the silicone is between 500 and 5000. Preferentially, the polydi(C ₁ -C ₄ )alkylsiloxanes of formula (IVd) have the formula (IV’d) below: in formula (IV’d), the value of n is such that the weight-average molecular weight of the silicone is between 500 and 3000. As examples of silicones (IVd), mention may be made of the products sold under the names MCR-A11 and MCR-A12 by the company Gelest; ▪ the amodimethicones of formula (IVe): in which formula (IVe): 22 R ^a and R ^b , which may be identical or different, preferably identical, represent a group from among: (C ₁ -C ₄ )alkyl such as methyl, (C ₁ -C ₄ )alkoxy such as methoxy, aryl such as phenyl, aryloxy such as phenoxy, aryl(C ₁ -C ₄ )alkyl such as benzyl, or aryl(C ₁ -C ₄ )alkoxy such as benzoxy, preferably (C ₁ -C ₄ )alkyl such as methyl; 5 R ^c represents a hydrogen atom or a (C ₁ -C ₄ )alkyl group, preferably a hydrogen atom; R ^e represents a hydroxyl, (C ₁ -C ₄ )alkoxy, amino or (C ₁ -C ₄ )alkylamino group; R ^f represents a (C ₁ -C ₄ )alkyl group such as methyl, a (C ₁ -C ₄ )alkoxy group such as methoxy, a hydroxyl or -O–(SiR ₂ ) _x -R’ group with R representing a (C ₁ -C ₄ )alkyl or (C ₁ -C ₄ )alkoxy group and R’ representing a (C ₁ -C ₄ )alkoxy or hydroxyl group; preferably, R ^f represents a (C ₁ - 10 C ₄ )alkyl, (C ₁ -C ₄ )alkoxy or -O–(SiR ₂ ) _x -R’ group with R representing a (C ₁ -C ₄ )alkyl group such as methyl and R’ a hydroxyl or (C ₁ -C ₄ )alkoxy group such as methoxy; ALK and ALK’, which may be identical or different, represent a (C ₁ -C ₆ )alkylene group, preferably (C ₁ -C ₄ )alkylene such as ethylene or propylene; n and m, which may be identical or different, represent an integer greater than 2, p and x are integers greater than or equal 15 to 0; preferably, p is between 2 and 20 and more particularly the values of m, n, p and x are such that the weight-average molecular weight of the silicone is between 2000 and 700 000, preferentially between 5000 and 500000. Preferentially, the amodimethicones of formula (IVe) are of formula (IV’e) or (IV”e) below: 20 in which formula (IV’e) ALK represents a (C ₁ -C ₆ )alkylene group, preferably ethylene, ALK’ represents a (C ₁ -C ₆ )alkylene group, preferably propylene, and m, n and p represent greater than 2, with m, n and p such that the weight-average molecular mass of the compound is approximately between 5000 and 500000; preferably, p represents an integer between 8 and 20; 23 in which formula (IV’’e): R ^a and R ^b , which may be identical or different, preferably identical, represent a (C ₁ -C ₄ )alkyl group such as methyl or a (C ₁ -C ₄ )alkoxy group such as methoxy, preferably a (C ₁ -C ₄ )alkyl 5 group such as methyl; R ^c represents a hydrogen atom or a (C ₁ -C ₄ )alkyl group, preferably a hydrogen atom; R ^g represents a hydrogen atom or a (C ₁ -C ₄ )alkyl group; R ^f represents a (C ₁ -C ₄ )alkyl group such as methyl, a (C ₁ -C ₄ )alkoxy group such as methoxy, or -O–(SiR ₂ ) _x -R’ with R representing a (C ₁ -C ₄ )alkyl group such as methyl and R’ a hydroxyl 10 or (C ₁ -C ₄ )alkoxy group such as methoxy; ALK represents a (C ₁ -C ₆ )alkylene group, preferably ethylene; ALK’ represents a (C ₁ -C ₆ )alkylene group, preferably propylene; n and m, which may be identical or different, representing an integer greater than 2, x is an integer greater than or equal to 0; preferably, the values of m, n and x are such that the 15 weight-average molecular weight of the silicone is between 2000 and 700000, preferentially between 5000 and 500000. Even more preferentially, the amodimethicones of formula (IVe) are of formula (IV’’’e) below:

(IV”’e) in which formula (IV”’e):

R ^f , R ^g , ALK, ALK’, m and n are as defined for (IV”e). The amodimethicones and trimethylsiloxy amodimethicones belonging to formula (IV”e) and to formula (IV”’e) above are, for example, the amodimethicones and trimethylsiloxy amodimethicones of ADM type sold by the company Wacker-Belsil®; mention may also be made of polydimethylsiloxanes bearing aminoethylaminopropyl groups, bearing a methoxy and/or hydroxyl function and a- co silanols as a cationic 60% aqueous emulsion (supplier reference: Xiameter MEM-8299 Emulsion by Dow Corning or under the supplier reference: Belsil ADM 4000 E by Wacker); polydimethylsiloxanes bearing aminoethyl iminopropyl groups, as a stored nonionic 15% microemulsion (supplier reference: Belsil ADM Log 1);

■ the polyether amines known notably under the reference Jeffamine from the company Huntsman; and notably: polyethylene glycol and/or polypropylene glycol a,co-diamines (bearing a chain-end amine function), such as those sold under the names Jeffamine D- 230, D-400, D-2000, D-4000, ED-600, ED-9000, ED-2003;

■ polytetrahydrofuran (or polytetramethylene glycol) a,co-diamines, polybutadiene a, codiamines;

■ polyamidoamine (PAMAM) dendrimers bearing amine terminal functions;

■ poly(meth)acrylates or poly(meth)acrylamides bearing primary or secondary amine side functions, such as poly(3-aminopropyl)methacrylamide or poly(2-aminoethyl) methacrylate; and

■ mixtures thereof.

As polyamine compounds bearing at least two primary amine and/or secondary amine groups, use is preferably made of polydi(Ci-C4)alkylsiloxanes comprising primary amine groups at the chain end and/or on side chains. 25 More preferentially, the polyamine compounds are chosen from those of formulae (IVb) and (IVe) as defined previously and even more preferentially from those of formulae (IV’b) and (IV’e) as defined previously. More preferably, the polyamine compounds are chosen from those of formula (IV’e). 5 Aminoalkoxysilanes Preferably, the aminoalkoxysilanes are of formula R’ ₁ Si(OR’ ₂ )z(R’ ₃ )x in which: - R’ ₁ is a linear or branched, saturated or unsaturated, cyclic or acyclic C ₁ -C ₆ hydrocarbon- based chain substituted with a group chosen from the amine groups NH ₂ or NHR with R 10 representing a C ₁ -C ₄ alkyl, an aryl or an aryloxy substituted with an amino group or with a C ₁ -C ₄ aminoalkyl group; R’ ₁ may be interrupted in its chain with a heteroatom (O, S, NH) or a carbonyl group (CO), R’ ₁ being linked to the silicon atom directly via a carbon atom, - R’ ₂ and R’ ₃ , which may be identical or different, represent a linear or branched alkyl group comprising from 1 to 6 carbon atoms, 15 - z denotes an integer ranging from 1 to 3, and - x denotes an integer ranging from 0 to 2, with z + x = 3. In particular, R’ ₁ is an acyclic chain. Preferably, R’ ₁ is a linear or branched, saturated or unsaturated C ₁ -C ₆ hydrocarbon-based chain substituted with an amine NH ₂ or NHR group, 20 with R representing a C1-C6 alkyl, a C3-C6 cycloalkyl or a C6 aromatic group. More preferentially, R’ ₁ is a saturated linear C ₁ -C ₆ hydrocarbon-based chain substituted with an amine group NH ₂ . Even more preferentially, R’ ₁ is a saturated linear C ₂ -C ₄ hydrocarbon- based chain substituted with an amine group NH ₂ . In particular, R’ ₂ represents an alkyl group comprising from 1 to 4 carbon atoms; preferably, 25 R’ ₂ represents a linear alkyl group comprising from 1 to 4 carbon atoms and more preferentially R’ ₂ represents an ethyl group. In particular, R’ ₃ represents an alkyl group comprising from 1 to 4 carbon atoms; preferably, R’ ₃ represents a linear alkyl group comprising from 1 to 4 carbon atoms and more preferentially R’ ₃ represents methyl or ethyl groups. 30 Preferably, z is equal to 3. According to a particular embodiment, the aminoalkoxysilanes are chosen from 3- aminopropyltriethoxysilane (APTES), 3-aminoethyltriethoxysilane (AETES), 3- aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-(m- aminophenoxy)propyltrimethoxysilane, p-aminophenyltrimethoxysilane and N-(2- 35 aminoethylaminomethyl)phenethyltrimethoxysilane, and mixtures thereof. 26 Preferably, the aminoalkoxysilanes are chosen from 3-aminopropyltriethoxysilane (APTES), 3-aminoethyltriethoxysilane (AETES), 3-aminopropylmethyldiethoxysilane and N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and mixtures thereof. More preferentially, the aminoalkoxysilane is 3-aminopropyltriethoxysilane (APTES). 5 Hydroxylated compounds The crosslinking agent(s) may be chosen from b’) organic or mineral, polymeric or non- polymeric, preferably organic or silicone-based, hydroxylated compounds chosen from polyhydroxylated compounds containing at least two hydroxyl groups. 10 The term “non-polymeric compound(s)” refers to one or more compounds which are not directly obtained via a monomer polymerization reaction. The hydroxylated compounds of the invention may be organic or mineral, preferably 15 organic. According to an advantageous variant, the hydroxylated compounds are silicone compounds, i.e. they include at least two hydroxyl groups, and at least one siloxane chain. 20 According to a particular embodiment of the invention, the hydroxylated compounds are mineral. The polyhydroxylated compounds may comprise other non-reactive chemical functions such as ester, amide, ketone or urethane functions. It is possible to use a mixture of different 25 polyhydroxylated compounds such as a mixture of organic and mineral polyhydroxylated compounds. Non-polymeric hydroxylated compounds According to one embodiment of the invention, the hydroxylated compounds are non- 30 polymeric compounds of formula (II): in which formula (II): q represents an integer greater than or equal to 2, preferably ranging from 2 to 10, more preferentially ranging from 2 to 5; 27 L denotes a saturated or unsaturated linear or branched, or a saturated or unsaturated (hetero)cyclic, multivalent (at least divalent) group, in particular comprising from 1 to 500 carbon and/or silicon atoms, more particularly from 2 to 40 carbon and/or silicon atoms, even more particularly from 3 to 30 carbon and/or silicon atoms, preferably from 6 to 20 5 carbon atoms; L being optionally interrupted and/or terminated with one or more heteroatoms or groups chosen from O, S, N, Si and C(X), and combinations thereof such as –O-, –O-C(X)-, -N(R)- C(X)- or -Si(R _c )(R _d )-O- with R representing a hydrogen atom or a (C ₁ -C ₆ )alkyl group such as methyl; and/or 10 L being optionally substituted with one or more halogen atoms, or a group chosen from R _a (R _b )N- and -(X’) _a -C(X)-(X”) _b -R _a ; - X, X’ and X”, which may be identical or different, represent an oxygen or sulfur atom, or a group N(R _b ); - a and b being equal to 0 or 1; preferably, the sum a + b is equal to 1; 15 - R _a and R _b , which may be identical or different, represent a hydrogen atom or a (C ₁ -C ₆ )alkyl or aryl(C ₁ -C ₄ )alkyl group such as benzyl; preferably, R _a and R _b represent a hydrogen atom; - R _c and R _d , which may be identical or different, represent a (C ₁ -C ₆ )alkyl, aryl(C ₁ -C ₄ )alkyl or (C ₁ -C ₆ )alkoxy group. 20 According to a particular embodiment of the invention, the hydroxylated compounds are of formula (II) in which: q represents an integer greater than or equal to 2, preferably ranging from 2 to 10, more preferentially ranging from 2 to 5; L denotes a saturated or unsaturated linear or branched, or saturated or unsaturated 25 (hetero)cyclic, multivalent (at least divalent) radical comprising from 8 to 30 carbon and/or silicon atoms, preferably from 10 to 20 carbon and/or silicon atoms, L also possibly being interrupted with one or more oxygen atoms, and/or comprises one or more functions chosen from amino, ether, thio ether, ester, thio ester, ketone, thio ketone, amide and thio amide functions. 30 According to this particular embodiment, the polyol compound is preferably a diol compound. According to this particular embodiment, L preferably denotes a multivalent, notably linear, C ₈ -C ₁₈ radical. 28 Preferentially, the polyol is a notably linear, in particular liposoluble C ₈ -C ₁₈ diol. Advantageously, the C ₈ -C ₁₈ chain is a hydrocarbon-based chain, i.e. formed from carbon and hydrogen. In particular, the polyol is a linear C ₈ -C ₁₆ and notably C ₁₀ -C ₁₄ diol. 5 As polyols according to this particular embodiment of the invention, mention may be made of 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, 1,16- hexadecanediol and 1,18-octadecanediol. Use is preferably made of 1,10-decanediol, 1,12-dodecanediol or 1,14-tetradecanediol. 1,12-Dodecanediol is preferentially used. 10 According to one embodiment of the invention, the hydroxylated compounds are polymeric. The polymeric hydroxylated compounds of the invention may be star, comb, brush and dendritic homopolymers or copolymers bearing hydroxyl units. The polymers may be of 15 natural origin such as polysaccharides or polypeptides, or of synthetic origin such as (meth)acrylic polymers, polyesters or polyglycols. The hydroxyl units may be present as terminal and/or side groups. The polymeric hydroxylated compounds are preferably organic or silicone compounds, 20 more preferentially of formula (V): in which formula (V): p represents an integer greater than or equal to 2; POLY denotes a polymeric radical which is preferably carbon-based or silicone-based; 25 POLY being optionally interrupted with one or more heteroatoms or groups chosen from O, S, N, Si and C(X), and combinations thereof such as –O-, –O-C(X)-, -N(R)-C(X)- or -Si(R _c )(R _d )-O- with R representing a hydrogen atom or a (C ₁ -C ₆ )alkyl group such as methyl; and/or POLY being optionally substituted with one or more halogen atoms, or a group chosen from 30 R _a (R _b )N- and -(X’) _a -C(X)-(X”) _b -R _a ; - X, X’ and X”, which may be identical or different, represent an oxygen or sulfur atom, or a group N(R _b ); - a and b being equal to 0 or 1; preferably, the sum a + b is equal to 1; 29 - R _a and R _b , which may be identical or different, represent a hydrogen atom or a (C ₁ -C ₁₀ )alkyl or aryl(C ₁ -C ₄ )alkyl group such as benzyl; preferably, R _a and R _b represent a hydrogen atom; and - R _c and R _d , which may be identical or different, represent a (C ₁ -C ₁₀ )alkyl, aryl(C ₁ -C ₄ )alkyl 5 or (C ₁ -C ₁₀ )alkoxy group. According to a particular embodiment of the invention, the polymeric hydroxylated compounds are of formula (V) in which: p represents an integer greater than or equal to 2; POLY denotes a carbon-based or silicone-based polymeric radical, POLY also possibly 10 containing one or more heteroatoms such as O, N or S, and/or one or more functions chosen from amino, (thio)-ester, (thio)-ketone, (thio)-amide, (thio)-urea and (thio)carbamate functions, and/or possibly being substituted with one or more linear or branched (C ₁ - C ₁₀ )alkyl or linear or branched (C ₁ -C ₁₀ )alkoxy groups, it being understood that when POLY is substituted, the hydroxyl groups may be borne by the substituent(s). 15 The weight-average molecular weight of the polyol polymer compounds, such as those of formula (V), is generally between 500 and 400000, preferably between 500 and 150000. Preferably, the polymeric hydroxylated compounds may be (poly)ol polymers, notably polyolefin (poly)ols, polydi(C ₁ -C ₆ )alkylsiloxane (poly)ols or polyester (poly)ols. Preferably, the (poly)ols are diols. 20 The polyolefin (poly)ols may be polydienes bearing hydroxyl end groups, for instance those described in FR-A-2 782 723. They may be chosen from (poly)ols derived from homopolymers and copolymers of polybutadiene, of polyisoprene and of poly(1,3- pentadiene). They preferably have a number-average molecular mass (Mn) of less than 7000, preferably between 1000 and 5000. Mention will be made in particular of the 25 hydroxylated polybutadienes sold by the company Cray Valley under the brand names Poly BD R45HTLO, Poly BD R45V and Poly BD R-20 LM, which will preferably be used hydrogenated; and also (poly)hydroxylated hydrogenated (1,2-polybutadienes), such as GI3000 of Mn = 3100, GI2000 (Mn = 2100) and GI1000 (Mn = 1500) sold by the company Nisso. 30 According to one embodiment of the invention, the polymeric hydroxylated compounds are polyolefin (poly)ols of formula (VI): 30 in which formula (VI): ALK ⁴ and ALK ⁵ , which may be identical or different, preferably different, represent a linear or branched (C ₁ -C ₆ )alkylene group, optionally substituted with one or more hydroxyl, thiol 5 or amino groups; preferably, ALK ⁴ represents a linear (C ₁ -C ₆ )alkylene group such as n- butylene, and ALK ⁵ represents a branched (C ₃ -C ₆ )alkylene group such as i-butylene; X represents an oxygen or sulfur atom or a group N(Ra) with Ra representing a hydrogen atom or a (C ₁ -C ₄ )alkyl group; preferably, X represents an oxygen or sulfur atom, more preferentially an oxygen atom; and 10 n and m, which may be identical or different, represent an integer, with n + m representing an integer greater than or equal to 1. Among the polyolefins bearing hydroxyl end groups of formula (VI), mention may be made preferentially of polyolefin homopolymers or copolymers bearing α,ω-hydroxy end groups, such as polyisobutylenes bearing α,ω-hydroxy end groups and the copolymers of formula 15 (VI’): notably those sold by Mitsubishi under the brand name Polytail. Hydrogenated polybutadiene diols are preferably used. According to one embodiment of the invention, the polymeric hydroxylated compounds are 20 selected from polyvinyl alcohols. Examples of polyvinyl alcohols include polyvinyl alcohol sold by the company Sigma-Aldrich under the reference Mowiol ® 8-88. The polydi(C ₁ -C ₆ )alkylsiloxane (poly)ols are particularly chosen from those of formula (VII): 31 in which formula (VII): R ^a and R ^b , which may be identical or different, preferably identical, represent a group from among: (C ₁ -C ₆ )alkyl optionally substituted with one or more hydroxyl, amino or thiol groups; 5 (C ₁ -C ₆ )alkoxy such as methoxy; aryl such as phenyl; aryloxy such as phenoxy; aryl(C ₁ - C ₄ )alkyl such as benzyl; or aryl(C ₁ -C ₄ )alkoxy such as benzoxy; preferably (C ₁ -C ₄ )alkyl such as methyl; n represents an integer greater than or equal to 1 and more particularly the value of n is such that the weight-average molecular weight of the silicone ranges from 500 to 55000; 10 in particular, n is an integer ranging from 1 to 100, preferably ranging from 5 to 50 and preferentially ranging from 10 to 30; and L ⁴ and L ⁵ , which may be identical or different, represent a covalent bond or a saturated or unsaturated, linear or branched, optionally cyclic hydrocarbon-based chain comprising from 1 to 100 carbon atoms, optionally interrupted with one or more heteroatoms such as oxygen,15 sulfur or nitrogen, in particular oxygen, more preferentially a (C ₁ -C ₆ )alkylene, (C ₁ - C6)alkylenoxy, oxy(C1-C6)alkylene, (C1-C6)alkylenoxy(C1-C6)alkylene, (C1- C ₆ )alkylenoxy(C ₁ -C ₆ )alkylenoxy or oxy(C ₁ -C ₆ )alkylenoxy(C ₁ -C ₆ )alkylene group; X represents an oxygen or sulfur atom, preferably an oxygen atom. 20 Preferably, the polydimethylsiloxane (poly)ols are chosen from those of formula (VII’): in which formula (VII’): L ⁴ and L ⁵ are as defined previously, and preferably represent a divalent group chosen from –R ₂ –, –O–R ₂ –, –R ₂ –O– and –R ₂ –O–R’ ₂ –, preferably –R ₂ –O–R’ ₂ –, with R ₂ and R’ ₂ , which 32 may be identical or different, representing a linear or branched (C ₂ -C ₆ )alkylene group, such as ethylene or propylene; and n represents an integer ranging from 1 to 100, preferably ranging from 5 to 50 and preferentially ranging from 10 to 30. 5 Polydimethylsiloxanes diols that may be used include those sold under the names KF-6000, KF-6001, KF-6002 and KF-6003 by the company Shin-Etsu Chemicals. Use is preferably made of the polydimethylsiloxane diol of formula (VII”): Use may also be made of dimethiconols, which are polydimethylsiloxanes bearing OH 10 terminal functions. Mention may be made, for example, of the product sold under the name Xiameter PMX-1502 Fluid by the company Dow Corning. According to a particular form of the invention, the polymeric hydroxylated compound(s) denote compounds of formula (IIIa) below: 15 in which formula (IIIa): R ₁ , which may be identical or different, independently represents a hydroxyl group; an alkyl group containing from 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms, notably 1 to 2 carbon atoms such as a methyl; an alkoxy group containing from 1 to 2 carbon atoms; or a 20 group –(CH ₂ ) _s -Si(R ₄ ) ₃ in which s denotes an integer ranging from 1 to 4 such as 2 and R ₄ independently denotes an alkoxy group containing from 1 to 2 carbon atoms; R’ ₂ and R” ₂ independently represent an alkyl group containing from 1 to 10 carbon atoms, preferably from 1 to 4 carbon atoms, notably 1 to 2 carbon atoms such as a methyl; a denotes an integer ranging from 0 to 10, b denotes an integer ranging from 0 to 500 with a+b > 4.

Among the silicones of formula (Illa), mention may be made of polydimethylsiloxanes (PDMS) bearing hydroxyl terminal functions, such as the compounds sold by the company Shin-Etsu under the name KF-9701 or X-21-5841 , or those sold by the company Sigma- Aldrich under the reference 481939 (Mn -550, -25 cSt), 481955 (-65 cSt), or 481963 (-750 cSt). Mention may also be made of the compounds sold by the company Gelest under the name DMS-S12 (16-32 cSt), DMS-S15 (45-85 cSt), DMS-S21 (90-120 cSt), DMS-S27 (700-800 cSt) or DMS-S31 (-1000 cSt).

According to a preferred embodiment, the silicone(s) of formula (Illa) used in the context of the invention are chosen from the compounds of formula (Illa) in which:

Ri independently represents an alkyl group containing from 1 to 10 carbon atoms, preferably from 1 to 4 carbon atoms and more particularly from 1 to 2 carbon atoms, such as a methyl;

R’2 and R”2 independently represent an alkyl group containing from 1 to 10 carbon atoms, preferably an alkyl group containing from 1 to 4 carbon atoms and more particularly from 1 to 2 carbon atoms such as a methyl; b denotes an integer ranging from 0 to 10, a denotes an integer ranging from 0 to 5 with a+b > 4.

According to a particular embodiment of the invention, the hydroxylated compounds are chosen from polymeric compounds such as hyperbranched polymers and dendrimers.

“Hyperbranched polymers” are molecular constructions having a branched structure, generally around a core. Their structure is generally free of symmetry. Specifically, the base units or monomers which served for the construction of the hyperbranched polymer may be of different nature and their distribution is irregular. The branches of the polymer may be of different nature and lengths. The number of base units, or monomers, may be different according to the different branchings. While being asymmetric, hyperbranched polymers may have an extremely branched structure, around a core; successive generations or layers of branching; a layer of terminal chains.

Hyperbranched polymers are generally derived from the polycondensation of one or more monomers ABx, A and B being reactive groups that are capable of reacting together, x being an integer greater than or equal to 2, but other preparation processes may be envisaged. Hyperbranched polymers are characterized by their degree of polymerization DP = 1-b, b being the percentage of non-terminal functions of B which have not reacted with a group A. Since the condensation is not systematic, unlike for the synthesis of dendrimers (see hereinbelow), the degree of polymerization is less than 100%. A terminal group T on the hyperbranched polymer can be made to react to obtain a particular function at the end of chains.

Several hyperbranched polymers can be combined together, by covalent bonding or another type of bonding, by means of their terminal groups. Such polymers, which are said to be bridged, are included in the definition of the hyperbranched polymers according to the present invention.

Numerous hyperbranched polymers and dendrimers have already been described. Reference may be made, for example, to: D.A. Tomalia et al., Angew. Chem. Int. Engl. 29, 138-175 (1990); N. Ardoin and D. Astruc, Bull. Soc. Chim. Fr. 132, 875-909 (1995); B.l. Voit, Acta Polymer, 46, 87-99 (1995).

Such polymers are described in particular in B.l. Voit, Acta Polymer, 46, 87-99 (1995); EP- 682 059; WO- 96/14346; WO-96/14345; WO-96/12754. Several hyperbranched polymers can be combined together, by covalent bonding or another type of bonding, by means of their terminal groups.

Such polymers, which are said to be bridged, are included in the definition of the hyperbranched polymers according to the present invention.

“Dendrimers” are macromolecules consisting of monomers which associate by means of an arborescent process around a multifunctional central core.

Dendrimers thus have a fractal (or fractal molecule) structure, consisting of a core, a given number of generations of branches (or wedges), of internal cavities originating from said branches of the molecule, and of terminal functions.

Dendrimers are, structurally, highly branched polymers and oligomers having a well-defined chemical structure.

Dendrimers may be in the form of an assembly of molecules of the same generation, the assembly being referred to as “monodisperse”; they may also be in the form of assemblies of different generations, which are referred to as being “polydisperse”. The definition of dendrimers according to the present invention includes monodisperse dendrimer assemblies as well as polydisperse dendrimer assemblies.

The generations of branches consist of structural units, which are identical for the same generation of branches and which may be identical or different for different generations of branches. All of the junction points of branches of the same generation are located an equal distance from the core; this corresponds to a generation.

The generations of branches extend radially in a geometrical progression from the core. The terminal groups of an n ^th generation dendrimer are the terminal functional groups of the branches of the n ^th generation, referred to as the terminal generation.

The definition of dendrimers given above includes molecules bearing symmetrical branching; it also includes molecules bearing non-symmetrical branching, for instance dendrimers in which the branches are lysine groups, in which the branching of one generation of wedges on the preceding generation takes place on the a and E amines of lysine, which leads to a difference in the length of the wedges of the various branches.

Dendrimers also known as “dense star polymers” or “starburst polymers” or “rod-shaped dendrimers” are included in the present definition of dendrimers. The molecules known as “arborols” and “cascade molecules” are also included in the definition of dendrimers according to the present invention.

Moreover, several dendrimers may be combined together, via a covalent bond or another type of bonding, by means of their terminal groups to give species known as “bridged dendrimers” or “dendrimer aggregates”. Such species are included in the definition of dendrimers according to the present invention.

Dendrimers may be in the form of an assembly of molecules of the same generation, the assembly being referred to as “monodisperse”; they may also be in the form of assemblies of different generations, which are referred to as being “polydisperse”. The definition of dendrimers according to the present invention includes monodisperse dendrimer assemblies as well as polydisperse dendrimer assemblies.

In cases where the process according to the invention uses one or more crosslinking agents chosen from hydroxylated compounds as defined previously, the process may advantageously use one or more amine catalysts, the amine catalyst(s) preferably being present in the composition(s) comprising the crosslinking agent(s).

The amine catalyst(s) may be chosen from catalysts bearing a tertiary amine function or bearing an aminidine function or bearing a guanidine function.

The catalysts bearing a tertiary amine function may be chosen from triethylamine, diisopropylethylamine, tri-n-propylamine, tri-n-butylamine, methyldibutylamine, N- methyldicyclohexylamine, N,N-dimethylcyclohexylamine, ethyldiisopropylamine, N,N- diethylcyclohexylamine, pyridine, 4-dimethylaminopyridine, N-methylpiperidine, N- ethylpiperidine, N-n-butylpiperidine, 1 ,2-dimethylpiperidine, N-methylpyrrolidine, 1 ,2- dimethylpyrrohdine, dimethylanihne, picoline, N,N-dimethylbenzylamme, bis(2- dimethylaminoethyl) ether, N,N,N’,N’,N”-pentamethyldiethylenetriamine, N,N,N’,N’- tetramethylethylenediamine, N-methylmorpholine, N-ethylmorpholine and 1 ,4- diazabicyclo[2.2.2]octane, and mixtures thereof. Diisopropylethylamine is preferably used.

The catalysts bearing an amidine function are, for example, 1 ,5-diazabicyclo[4.3.0]non-5- ene (or DBN) and 1 ,8-diazabicyclo[5.4.0]undec-7-ene (or DBU).

The catalysts bearing a guanidine function may be chosen from the compounds of formula (la) below: in which R1 , R2, R3, R4 and R5 independently represent a hydrogen atom or a linear or branched C1-C4 lower alkyl or alkenyl radical, when R1 , R2 and R3 and R4 represent a hydrogen atom, R5 may also denote a radical from among: acetyl; carboxamide; methoxy; ethoxy; 1 ,2,4-triazolyl; cyclopentyl; methoxycarbonyl; ethoxycarbonyl; phenyl; benzyl; thiazolidone; benzimidazole; benzoxazole; benzothiazole; or C(=NH)-NR6R7 in which R6 and R7 denote, independently of each other, a hydrogen atom or a linear or branched C1-C4 lower alkyl radical; or else a phenyl radical, when R1=R2=R3=H, R4 and R5 may also form, with the nitrogen atom that bears them, a pyrrolidine, piperidine, pyrazole or 1 ,2,4-triazole ring, when R1=R2=H, and R4=H or methyl, R3 and R5 may also together form a 5-membered ring optionally containing an oxo group, and the organic or mineral salts thereof.

Salts that may be mentioned include the hydrochloride, sulfate, sulfamate, carbonate, bicarbonate, phosphate and acetate salts.

As compounds of formula (la), mention may notably be made of the following compounds: guanidine, aminoguanidine, 1-acetylguanidine, guanylurea, phenylguanidine, 1 ,1- dimethylguanidine, 1-ethylguanidine, 1 , 1-diethylguanidine, creatine, agmatine, biguanide, N-methylbiguanide, N-ethylbiguanide, N-propylbiguanide, N-butylbiguanide, 1 ,1- dimethylbiguanide, 1-phenylbiguanide, 1,1 ,3,3-tetramethylguanidine, 2-tert-butyl-1 , 1 ,3,3- tetramethylguanidine, 1H-pyrazole-1-carboxamidine, 5-hydroxy-3-methyl-1H-pyrazole-1- carboximidamide, 3,5-diamino-1H-1,2,4-triazole-1-carboximidamide, 2-guanidone-4- thiazolidone, 2-guanidinobenzimidazole, 2-guanidinobenzoxazole, 2- guanidinobenzothiazole, 1 ,1,3,3-tetramethylguanidine (or TMG), 1,5,7- triazabicyclo[4.4.0]dec-5-ene (or TBD), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (or MTBD).

Thiol compounds

The crosslinking agent(s) may be chosen from c’) organic or mineral, polymeric or non- polymeric thiol compounds, preferably organic or silicone-based thiol compounds, chosen from polythiol compounds containing at least two thiol groups.

The term “non-polymeric compound(s)” refers to one or more compounds which are not directly obtained via a monomer polymerization reaction.

The thiol compounds of the invention may be organic or mineral, preferably organic.

According to an advantageous variant, the thiol compounds are silicone compounds, i.e. they include at least two thiol groups, and at least one siloxane chain.

According to a particular embodiment of the invention, the thiol compound(s) are mineral. Mention may be made, for example, of polythiol silicones and polythiol silicas.

The thiol compounds of the invention may or may not be liposoluble. The term “liposoluble compound” means a compound that is soluble or miscible to at least 1% by weight in isododecane at 25°C.

Non-polymeric thiol compounds According to one embodiment of the invention, the thiol compounds are non-polymeric compounds of formula (HA):

L(SH)q (HA) in which formula (HA): 38 q represents an integer greater than or equal to 2, preferably ranging from 2 to 10, more preferentially ranging from 2 to 5; L denotes a saturated or unsaturated linear or branched, or a saturated or unsaturated (hetero)cyclic, multivalent (at least divalent) group, in particular comprising from 1 to 500 5 carbon and/or silicon atoms, more particularly from 2 to 40 carbon and/or silicon atoms, even more particularly from 3 to 30 carbon and/or silicon atoms, preferably from 6 to 20 carbon atoms; L being optionally interrupted and/or terminated with one or more heteroatoms or groups chosen from O, S, N, Si and C(X), and combinations thereof such as –O-, –O-C(X)-, -N(R)- 10 C(X)- or -Si(R _c )(R _d )-O- with R representing a hydrogen atom or a (C ₁ -C ₆ )alkyl group such as methyl; and/or L being optionally substituted with one or more halogen atoms, or a group chosen from R _a (R _b )N- and -(X’) _a -C(X)-(X”) _b -R _a ; - X, X’ and X”, which may be identical or different, represent an oxygen or sulfur atom, or a 15 group N(R _b ); - a and b being equal to 0 or 1; preferably, the sum a + b is equal to 1; - R _a and R _b , which may be identical or different, represent a hydrogen atom or a (C ₁ -C ₆ )alkyl or aryl(C ₁ -C ₄ )alkyl group such as benzyl; preferably, R _a and R _b represent a hydrogen atom; - R _c and R _d , which may be identical or different, represent a (C ₁ -C ₆ )alkyl, aryl(C ₁ -C ₄ )alkyl or 20 (C1-C6)alkoxy group. According to this embodiment, the polythiol compound is preferably a dithiol compound. According to this embodiment, L preferably denotes a multivalent, notably linear, C ₈ -C ₁₈ radical. Preferentially, the polythiol is a notably linear C ₈ -C ₁₈ dithiol. Advantageously, the C ₈ -C ₁₈ chain is a hydrocarbon-based chain, i.e. formed from carbon and hydrogen. In 25 particular, the liposoluble polythiol is a linear C ₈ -C ₁₆ and notably C ₁₀ -C ₁₄ dithiol. As polythiol of formula (IIA), mention may be made of 1,8-octanedithiol, 1,10-decanedithiol, 1,12-dodecanedithiol, 1,14-tetradecanedithiol, 1,16-hexadecanedithiol and 1,18- octadecanedithiol. Use is preferably made of 1,10-decanedithiol, 1,12-dodecanedithiol or 1,14- 30 tetradecanedithiol.1,12-Dodecanedithiol is preferentially used. According to a particular embodiment of the invention, the thiol compounds are non- polymeric compounds of formula (IB): 35 in which formula (IB): 39 n denotes an integer greater than or equal to 2, preferably ranging from 2 to 10, preferably ranging from 2 to 5, and W denotes a linear or branched or (hetero)cyclic, saturated C ₂ -C ₈₀ multivalent (at least divalent) radical, an aromatic radical, or a heteroaromatic cyclic radical, W also possibly containing one or more heteroatoms such as O, N or S and/or one or more 5 functions chosen from ester, ketone, amide and urea functions, preferably ester and ketone functions, and/or possibly being substituted with one or more linear or branched C ₁ -C ₁₀ alkyl or linear or branched C ₁ -C ₁₀ alkoxy groups, it being understood that when the radical W is substituted, the thiol functions may be borne by the substituent(s). The term “cyclic radical” means a hydrocarbon-based or heterocyclic saturated monocyclic 10 radical, a saturated or aromatic polycyclic radical, for example biphenyl, or fused rings, for instance a naphthyl radical. The molar mass of the compounds of formula (IB) generally ranges from 90 to 1500. According to a more particular first embodiment, the thiol compounds of formula (IB) are such that n = 2 and W denotes a linear or branched C ₂ -C ₂₀ , preferably linear or branched 15 C ₂ -C ₁₂ saturated divalent hydrocarbon-based radical. According to this more particular first embodiment, the thiol compounds may be chosen from: 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,6- hexanedithiol, 1,7-heptanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 1,12-dodecanedithiol, 2,2-dimethyl-1,3-propanedithiol, 3-methyl-1,5-pentanedithiol, 2- 20 methyl-1,8-octanedithiol. According to a more particular second embodiment, the thiol compounds of formula (IB) are such that n = 3 and W denotes a linear or branched C ₃ -C ₂₀ , preferably linear or branched C ₂ -C ₁₂ saturated trivalent hydrocarbon-based radical. According to this more particular second embodiment, the thiol compounds may be chosen 25 from 1,1,1-tris(mercaptomethyl)ethane, 2-ethyl-2-mercaptomethyl-1,3-propanedithiol and 1,2,3-propanetrithiol. According to a more particular third embodiment, the thiol compounds of formula (IB) are such that n = 2 or 3 and W denotes a linear or branched C ₃ -C ₂₀ , preferably linear or branched C ₂ -C ₁₂ saturated divalent or trivalent hydrocarbon-based radical, said radical 30 containing one or more non-adjacent heteroatoms chosen from O and S. According to this more particular third embodiment, the thiol compounds may be chosen from: C ₂ -C ₁₂ bis-mercaptoalkyl ethers and sulfides such as bis(2-mercaptoethyl) ether, bis(2- mercaptoethyl) sulfide and bis(2-mercaptoethylthio-3-mercaptopropane) sulfide; 40 bis(2-mercapto((C ₁ -C ₃ )alkyl)thio) (C ₁ -C ₅ )alkanes or bis(2-mercapto((C ₁ -C ₃ )alkyl)thio) (C ₁ - C ₅ )mercaptoalkanes, for instance bis(2-mercaptoethylthio)methane, 1,2-bis(2- mercaptoethylthio)ethane, 1,3-bis(2-mercaptoethylthio)propane, 1,2-bis(2- mercaptoethylthio)propanethiol, 1,2-bis(2-mercaptoethyl)thio-3-mercaptopropane, or 1,2,3- 5 tris(2-mercaptoethylthio)propane. Preferably, according to this more particular third embodiment, the thiol compounds are chosen from 1,2-bis(2-mercaptoethylthio)propanethiol, 1,2,3-tris(2- mercaptoethylthio)propane and tetrakis(2-mercaptoethylthiomethyl)methane. 10 According to a more particular fourth embodiment, the thiol compounds of formula (IB) are such that n denotes an integer greater than or equal to 2 and W denotes a linear or branched C ₃ -C ₂₀ , preferably linear or branched C ₂ -C ₁₂ , hydrocarbon-based saturated multivalent (at least divalent) radical, said radical containing at least one ester function. According to this more particular fourth embodiment, the thiol compounds may be chosen 15 from: esters of polyols (glycols, triols, tetraols, pentaols, hexaols) and of C ₁ -C ₆ mercaptocarboxylic acid, such as ethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), ethylene glycol bis(thioglycolate), trimethylolpropane tris(thioglycolate), trimethylolpropane tris(β-mercaptopropionate), pentaerythrityl 20 tetrakis(thioglycolate), pentaerythrityl tetrakis(β-mercaptopropionate), dipentaerylthrityl hexakis(β-mercaptoproprionate), trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), pentaerythrityl tetrakis(2-mercaptoacetate), pentaerythrityl tetrakis(3-mercaptopropionate), pentaerythrityl tetrakis(3- mercaptobutanate), and dipentaerythrityl hex-3-mercaptopropionate. 25 Preferably, according to this more particular fourth embodiment, the thiol compounds are chosen from trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3- mercaptopropionate), pentaerythrityl tetrakis(2-mercaptoacetate), pentaerythrityl tetrakis(3- mercaptopropionate), pentaerythrityl tetrakis(3-mercaptobutanate) and dipentaerythrityl hex-3-mercaptopropionate. 30 Particularly preferably, the thiol compound is pentaerythrityl tetrakis(3- mercaptopropionate). According to a more particular fifth embodiment, the thiol compounds of formula (IB) are such that n = 4 and W denotes a branched C ₄ -C ₂₀ , preferably C ₈ -C ₁₄ saturated tetravalent hydrocarbon-based radical interrupted with one or more non-adjacent sulfur atoms. According to this more particular fifth embodiment, the thiol compounds may be chosen from tetrakis(2-mercaptoethylthiomethyl)methane and bis(2-mercaptoethylthio-3- mercaptopropane) sulfide.

According to a more particular sixth embodiment, the thiol compounds of formula (IB) are such that n = 2 and W denotes a hydrocarbon-based cyclic divalent radical optionally containing one or more non-adjacent sulfur atoms, optionally substituted with one or more linear or branched C1-C10 alkyl radicals.

According to this more particular sixth embodiment, the thiol compounds may be chosen from 1 ,4-cyclohexanedithiol, 1 ,4-bis(mercaptomethyl)cyclohexane, 1 ,1-cyclohexanedithiol,

1.2-cyclohexanedithiol, 1 ,1-bis(mercaptomethyl)cyclohexane and 2,5-dimercapto-1 ,4- dithiane.

According to a more particular seventh embodiment, the thiol compounds of formula (IB) are such that n = 3 and W denotes a substituted cyclic radical of isocyanurate type.

According to this more particular seventh embodiment, the thiol compounds may be chosen from polythiols of the isocyanurate class, described in patents US 3676440 and US 2011/0 230 585, such as tris((mercaptopropionyloxy)ethyl) isocyanurate.

According to a more particular eighth embodiment, the thiol compounds of formula (IB) are such that n = 2 or 3 or 4 and W denotes an aromatic radical optionally substituted with one or more identical or different radicals of (Ci-C )alkyl or (Ci-Cw)alkoxy type, it being understood that when the radical W is substituted, the thiol functions may be borne by the substituent(s).

According to this more particular eighth embodiment, the thiol compounds may be chosen from:

1 .2-dimercaptobenzene, 1 ,3-dimercaptobenzene,

1 ,4-dimercaptobenzene, 1 ,2-bis(mercaptomethyl)benzene,

1 .3-bis(mercaptomethyl)benzene,

1 .4-bis(mercaptomethyl)benzene,

1.2-bis(2-mercaptoethyl)benzene,

1.3-bis(2-mercaptoethyl)benzene,

1.4-bis(2-mercaptoethyl)benzene,

1.2-bis(2-mercaptoethyleneoxy)benzene,

1.3-bis(2-mercaptoethyleneoxy)benzene,

1.4-bis(2-mercaptoethyleneoxy)benzene,

1 ,2, 3- trimercaptobenzene, 1 .2.4- trimercaptobenzene,

1 .3.5- trimercaptobenzene,

1.2.3-tris(mercaptomethyl)benzene,

1.2.4-tris(mercaptomethyl)benzene,

1.3.5-tris(mercaptomethyl)benzene,

1.2.3-tris(2-mercaptoethyl)benzene,

1.2.4-tris(2-mercaptoethyl)benzene,

1.3.5-tris(2-mercaptoethyl)benzene,

1.2.3-tris(2-mercaptoethyleneoxy)benzene,

1.2.4-tris(2-mercaptoethyleneoxy)benzene,

1.3.5-tris(2-mercaptoethyleneoxy)benzene,

1 .2.3.4-tetramercaptobenzene,

1 .2.3.5-tetramercaptobenzene,

1 .2.4.5-tetramercaptobenzene,

1.2.3.4-tetrakis(mercaptomethyl)benzene,

1.2.3.5-tetrakis(mercaptomethyl)benzene,

1.2.4.5-tetrakis(mercaptomethyl)benzene,

1.2.3.4-tetrakis(2-mercaptoethyl)benzene,

1.2.3.5-tetrakis(2-mercaptoethyl) benzene,

1.2.4.5-tetrakis(2-mercaptoethyl)benzene,

1.2.3.4-tetrakis(2-mercaptoethyleneoxy)benzene,

1.2.3.5-tetrakis(2-mercaptoethyleneoxy)benzene,

1.2.4.5-tetrakis(2-mercaptoethyleneoxy)benzene, 2,2’-dimercaptobiphenyl, 4,4’-dimercaptobiphenyl,

4,4’-dimercaptobibenzyl,

2.5-toluenedithiol,

3.4-toluenedithiol,

1.4-naphthalenedithiol,

1.5-naphthalenedithiol,

2.6-naphthalenedithiol,

2.7-naphthalenedithiol,

2.4-dimethylbenzene-1 ,3-dithiol,

4.5-dimethylbenzene-1 ,3-dithiol, 9, 10-anthracenedimethanethiol, 1.3-bis(2-mercaptoethylthio)benzene,

1.4-bis(2-mercaptoethylthio)benzene,

1.2-bis(2-mercaptoethylthiomethyl)benzene,

1.3-bis(2-mercaptoethylthiomethyl)benzene,

1.4-bis(2-mercaptoethylthiomethyl)benzene,

1.2.3-tris(2-mercaptoethylthio)benzene,

1.2.4-tris(2-mercaptoethylthio)benzene,

1.3.5-tris(2-mercaptoethylthio)benzene,

1.2.3.4-tetrakis(2-mercaptoethylthio)benzene,

1.2.3.5-tetrakis(2-mercaptoethylthio)benzene,

1.2.4.5-tetrakis(2-mercaptoethylthio)benzene,

3,4-thiophenedithiol.

According to this more particular eighth embodiment, the thiol compounds may be chosen from 1 ,2,3-trimercaptobenzene, 1 ,2,4-trimercaptobenzene, 1 ,3,5-trimercaptobenzene,

1 ,2,3-tris(mercaptomethyl)benzene, 1.2.4-tris(mercaptomethyl)benzene, 1 ,3,5- tris(mercaptomethyl)benzene, 1 ,2,3-tris(2-mercaptoethyl)benzene, 1.2.4-tris(2- mercaptoethyl)benzene, 1 ,3,5-tris(2-mercaptoethyl)benzene, 1 ,2,3-tris(2- mercaptoethyleneoxy)benzene, 1 ,2,4-tris(2-mercaptoethyleneoxy)benzene, 1.3.5-tris(2- mercaptoethyleneoxy)benzene, 1.2.3.4-tetramercaptobenzene, 1 ,2,3,5- tetramercaptobenzene, 1.2.4.5-tetramercaptobenzene, 1.2.3.4- tetrakis(mercaptomethyl)benzene, 1.2.3.5-tetrakis(mercaptomethyl)benzene, 1.2.4.5- tetrakis(mercaptomethyl)benzene, 1.2.3.4-tetrakis(2-mercaptoethyl)benzene, 1.2.3.5- tetrakis(2-mercaptoethyl)benzene, 1.2.4.5-tetrakis(2-mercaptoethyl)benzene, 1 , 2,3,4- tetrakis(2-mercaptoethyleneoxy)benzene, 1 ,2,3,5-tetrakis(2- mercaptoethyleneoxy)benzene, 1 ,2,4,5-tetrakis(2-mercaptoethyleneoxy)benzene, 1 ,2,3- tris(2-mercaptoethylthio)benzene, 1 ,2,4-tris(2-mercaptoethylthio)benzene, 1 , 3, 5-tris(2- mercaptoethylthio)benzene, 1 ,2,3,4-tetrakis(2-mercaptoethylthio)benzene, 1 ,2,3,5- tetrakis(2-mercaptoethylthio)benzene, 1 ,2,4,5-tetrakis(2-mercaptoethylthio)benzene and

3,4-thiophenedithiol.

According to a more particular ninth embodiment, the thiol compounds of formula (IB) are such that n = 2 or 3 or 4 and W denotes a fatty acid triglyceride or a plant oil, which are optionally substituted, it being understood that when the radical W is substituted, the thiol functions may be borne by the substituent(s). 44 According to another particular embodiment of the invention, the thiol compounds are chosen from thiol-based fatty acid triglyceride derivatives, such as those of formula (IV) below: 5 in which formula (IV): R ¹ , R ² and R ³ , which may be identical or different, represent a hydrogen atom or a thiol group; ALK ¹ , ALK ² and ALK ³ , which may be identical or different, represent a (C ₁ -C ₃₀ )alkylene 10 group optionally substituted with one or more thiol groups; X ¹ , X ² and X ³ , which may be identical or different, preferably identical, represent a group -C(Y)-Y’- or -Y’-C(Y)- with Y and Y’, which may be identical or different, preferably identical, representing a heteroatom such as O, S and N, preferably O. 15 Preferably, the compounds of formula (IV) are such that: R ¹ , R ² and R ³ represent a hydrogen atom; ALK ¹ represents a (C ₁₀ -C ₂₄ )alkylene and particularly (C ₁₄ -C ₂₀ )alkylene group, which is preferably linear; ALK ² represents a (C ₁₀ -C ₂₄ )alkylene and particularly (C ₁₄ -C ₂₀ )alkylene group, which is 20 preferably linear, substituted with one or more thiol groups; ALK ³ represents a (C ₁₀ -C ₂₄ )alkylene and particularly (C ₁₄ -C ₂₀ )alkylene group, which is preferably linear, substituted with one or more thiol groups, preferably two thiol groups; X ¹ , X ² and X ³ , which are identical, represent a -C(O)-O- or -O-C(O)- group. More preferentially, the thiol-based fatty acid triglyceride derivatives are those of formula 25 (IV’) below:

According to this other particular embodiment, the thiol compounds may be chosen from: fatty acid triglycerides or plant oils modified with thiol groups by chemical reaction, for instance thiolated soybean oils and hydroxylated and thiolated soybean oils, notably the polymercaptan® products from the company Chevron Phillips, such as Polymercaptan 358 (mercaptanized soybean oil) and Polymercaptan 407 (mercapto hydroxy soybean oil).

According to a particular embodiment of the invention, the thiol compounds are chosen from polythiol compounds containing several thiol groups, and having a weight-average molecular weight ranging from 500 to 1 000 000, preferably ranging from 500 to 500 000 and preferentially ranging from 500 to 100 000.

According to this variant, preference will be given to the compounds of formula (IB) for which n denotes an integer greater than or equal to 3, preferably ranging from 3 to 10 and more preferentially ranging from 3 to 5.

Preferably, according to this variant, the thiol compounds are chosen from compounds of the more particular second embodiment; or from compounds of the more particular third embodiment; or from compounds of the more particular fourth embodiment, in particular such as trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3- mercaptopropionate), pentaerythrityl tetrakis(2-mercaptoacetate), pentaerythrityl tetrakis(3- mercaptopropionate), pentaerythrityl tetrakis(3-mercaptobutanate) or dipentaerythrityl hex- 3-mercaptopropionate; or from compounds of the more particular fifth embodiment; or from compounds of the more particular seventh embodiment, in particular such as tris((mercaptopropionyloxy)ethyl) isocyanurate.

Particularly preferably, according to this variant, the thiol compounds denote trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), pentaerythrityl tetrakis(2-mercaptoacetate), pentaerythrityl tetrakis(3-mercaptopropionate), pentaerythrityl tetrakis(3-mercaptobutanate), dipentaerythrityl hex-3-mercaptopropionate or tris((mercaptopropionyloxy)ethyl) isocyanurate. 46 According to one embodiment of the invention, the thiol compounds are polymeric. The polymeric thiol compounds of the invention may be star, comb, brush and dendritic homopolymers or copolymers bearing thiol units. The polymers may be of natural origin 5 such as polysaccharides or peptides, or of synthetic origin such as acrylic polymers or polyesters. The thiol units may be present as terminal and/or side groups. The polymeric thiol compounds are preferably organic or silicone compounds, more preferentially of formula (VB): 10 in which formula (VB): q is an integer greater than or equal to 2; POLY denotes a polymeric radical which is preferably carbon-based or silicone-based; POLY being optionally interrupted with one or more heteroatoms or groups chosen from O, 15 S, N, Si and C(X), and combinations thereof such as –O-, –O-C(X)-, -N(R)-C(X)- or -Si(R _c )(R _d )-O- with R representing a hydrogen atom or a (C ₁ -C ₆ )alkyl group such as methyl; and/or POLY being optionally substituted with one or more halogen atoms, or a group chosen from R _a (R _b )N- and -(X’) _a -C(X)-(X”) _b -R _a ; 20 - X, X’ and X”, which may be identical or different, represent an oxygen or sulfur atom, or a group N(R _b ); - a and b being equal to 0 or 1; preferably, the sum a + b is equal to 1; - R _a and R _b , which may be identical or different, represent a hydrogen atom or a (C ₁ -C ₁₀ )alkyl or aryl(C ₁ -C ₄ )alkyl group such as benzyl; preferably, R _a and R _b represent a hydrogen atom; 25 and - R _c and R _d , which may be identical or different, represent a (C ₁ -C ₁₀ )alkyl, aryl(C ₁ -C ₄ )alkyl or (C ₁ -C ₁₀ )alkoxy group. The methods for preparing the thiol-based polymers according to the invention are known 30 to those skilled in the art; several methods are reported hereinbelow in a non-limiting manner. The thiol-based polymers according to the invention may be obtained by polymerization or polycondensation of monomer units bearing thiol or protected thiol functions, optionally as 47 a copolymerization or co-polycondensation of monomer units free of thiol or protected thiol functions. Alternatively, the thiol-based polymers according to the invention may be obtained by addition of hydrogen sulfide, of salts thereof such as sodium hydrogen sulfide or potassium 5 sulfide or alternatively a group that is capable of forming a carbon-sulfur bond such as thiourea derivatives or thiosulfate, on a polymer bearing at least one double bond. The thiol-based polymers according to the invention may also be obtained by nucleophilic substitution of a leaving group present on a polymer chain (for example a halogen such as chlorine or bromine, or a sulfonic ester such as mesylate or tosylate) with a compound 10 including at least one sulfur atom such as those mentioned previously. The thiol-based polymers according to the invention may also be obtained by reaction of polymers including nucleophilic groups such as amines on electrophilic compounds including a sulfur atom, such as 2-oxo-4-thiazolidinecarboxylic acid, also known as procysteine: 15 - N-acetyl homocysteine thiolactone: - - iminothiolane: 20 According to one embodiment of the invention, the polymeric thiol compounds are of formula (VIIIB): 25 in which formula (VIIIB): q denotes an integer greater than or equal to 2, and POLY denotes a carbon-based and/or silicone-based, preferably silicone-based, polymeric radical, POLY also possibly containing one or more heteroatoms such as O, N or S, and/or 48 one or more functions chosen from (thio)-ester, (thio)-ketone, (thio)-amide, (thio)urea and (thio)carbamate functions, and/or possibly being substituted with one or more linear or branched (C ₁ -C ₁₀ )alkyl or linear or branched (C ₁ -C ₁₀ )alkoxy groups, it being understood that when POLY is substituted, the thiol functions may be borne by the substituent(s). 5 The weight-average molecular weight of the polythiol polymer compounds, such as those of formula (VIIIB), generally ranges from 500 to 400000, preferably from 500 to 150000. According to a particular embodiment of the invention, the polymeric thiol compound(s) are chosen from the polyorganosiloxanes of formula (VIIIB’): 10 in which formula (VIIIB’): R ^a and R ^b , which may be identical or different, preferably identical, represent a group from among: (C ₁ -C ₄ )alkyl such as methyl, (C ₁ -C ₄ )alkoxy such as methoxy, aryl such as phenyl, aryloxy such as phenoxy, aryl(C ₁ -C ₄ )alkyl such as benzyl, or aryl(C ₁ -C ₄ )alkoxy such as 15 benzoxy, preferably (C ₁ -C ₄ )alkyl such as methyl; n represents an integer greater than or equal to 1 and more particularly the value of n is such that the weight-average molecular weight of the silicone ranges from 500 to 55000; in particular, n is an integer ranging from 1 to 100, preferably ranging from 5 to 50 and preferentially ranging from 10 to 30; and 20 L ⁴ and L ⁵ , which may be identical or different, represent a covalent bond, or a linear or branched, saturated or unsaturated, optionally cyclic hydrocarbon-based chain comprising from 1 to 100 carbon atoms, optionally interrupted with one or more heteroatoms such as oxygen, sulfur or nitrogen, in particular oxygen; preferably, L ⁴ and L ⁵ , which may be identical or different, represent a covalent bond or a (C ₁ -C ₆ )alkylene, (C ₁ -C ₆ )alkylenoxy, oxy(C ₁ - 25 C ₆ )alkylene, (C ₁ -C ₆ )alkylenoxy(C ₁ -C ₆ )alkylene, (C ₁ -C ₆ )alkylenoxy(C ₁ -C ₆ )alkylenoxy or oxy(C ₁ -C ₆ )alkylenoxy(C ₁ -C ₆ )alkylene group, preferably a (C ₁ -C ₆ )alkylene, (C ₁ - C ₆ )alkylenoxy, oxy(C ₁ -C ₆ )alkylene or (C ₁ -C ₆ )alkylenoxy(C ₁ -C ₆ )alkylene group. Preferentially, the polydimethylsiloxane thiols are chosen from those of formula (VIIIB’’): 49 in which formula (VIIIB’’): L ⁴ and L ⁵ represent a linear or branched, optionally cyclic, saturated or unsaturated hydrocarbon-based chain comprising from 1 to 100 carbon atoms, optionally interrupted 5 with one or more heteroatoms such as oxygen, sulfur or nitrogen, in particular oxygen; preferably L ⁴ a L ⁵ represent a (C ₁ -C ₆ )alkylene, (C ₁ -C ₆ )alkylenoxy, oxy(C ₁ -C ₆ )alkylene or (C1-C6)alkylenoxy(C1-C6)alkylene group, more preferentially a divalent group chosen from –R ₂ –, –O–R ₂ –, –R ₂ –O– and –R ₂ –O–R ₂ –, preferably –R ₂ –O–R ₂ –, with R ₂ representing a linear or branched, preferably linear, (C ₂ -C ₆ )alkylene group, such as ethylene or n- 10 propylene; n represents an integer ranging from 1 to 100, preferably ranging from 5 to 50 and preferentially ranging from 10 to 30. As thiol-based poly(C ₁ -C ₄ )alkylsiloxanes, mention may be made of mercaptosiloxanes or thiol-based siloxanes in which the thiol functions are at the chain ends, sold by the company 15 Shin-Etsu under the reference X-22-167B, and mercaptosiloxane in which the mercapto functions are pendent, sold by the company Shin-Etsu under the reference KF-2001, or polydimethylsiloxanes in which the thiol functions are at the chain ends, sold by the company Gelest under the name DMS-SM 21, of formula (VIII’’’): 20 Preferably, the polymeric thiol compounds are chosen from those of formula (IX): 50 in which formula (IX): R ^a , R ^b and R ^d , which may be identical or different, preferably identical, represent a group from among: (C ₁ -C ₆ )alkyl group optionally substituted with a hydroxyl or amino group, 5 preferably (C ₁ -C ₄ )alkyl such as methyl; (C ₁ -C ₄ )alkoxy such as methoxy; aryl such as phenyl; aryloxy such as phenoxy; aryl(C ₁ -C ₄ )alkyl such as benzyl; or aryl(C ₁ -C ₄ )alkoxy such as benzoxy; preferably (C ₁ -C ₄ )alkyl such as methyl; R ^d may also represent a (C ₁ -C ₆ )alkyl group substituted with a (C ₁ -C ₄ )alkylamino or amino or thiol group, preferably (C1-C4)alkyl such as methyl; 10 ALK represents a linear or branched, optionally cyclic, saturated or unsaturated hydrocarbon-based chain comprising from 1 to 100 carbon atoms, optionally interrupted with one or more heteroatoms such as oxygen, sulfur or nitrogen (in particular O), a (thio)carbonyl group C(X) with X representing O or S, or combinations thereof such as –O– , –O-C(O)– or –C(O)-O–; preferably, ALK represents a (C ₁ -C ₆ )alkylene and more 15 preferentially (C ₁ -C ₄ )alkylene group such as propylene; n and m, which may be identical or different, representing an integer greater than 2, and more particularly the values of m and n are such that the weight-average molecular weight of the silicone ranges from 1000 to 55 000; Preferentially, the polydi(C ₁ -C ₄ )alkylsiloxanes of formula (IX) have the formula (IX’) below: 20 in which formula (IX’) the values of n and m are such that the weight-average molecular weight of the silicone ranges from 1000 to 55000. As examples of silicones (IX’), mention may be made of the products GP-367 and others sold by Genesee Polymers. The polythiol silicones are notably polydimethylsiloxanes including at least two thiol groups, for instance the products SMS-022, SMS 042 and SMS 992 sold by the company Gelest In https://www.gpcsilicones.com/products/silicone-fluids/mercap to- functional,https://www.shinetsusilicone- global.com/products/type/oil/detail/search/deg07.shtml, and 1053_Reactive Silicones_Silanes/Silicones - Gelest.

According to a particular embodiment of the invention, the thiol compounds are chosen from polymeric compounds such as hyperbranched polymers and dendrimers.

“Hyperbranched polymers” are molecular constructions having a branched structure, generally around a core. Their structure is generally free of symmetry. Specifically, the base units or monomers which served for the construction of the hyperbranched polymer may be of different nature and their distribution is irregular. The branches of the polymer may be of different nature and lengths. The number of base units, or monomers, may be different according to the different branchings. While being asymmetric, hyperbranched polymers may have an extremely branched structure, around a core; successive generations or layers of branching; a layer of terminal chains.

Hyperbranched polymers are generally derived from the polycondensation of one or more monomers ABx, A and B being reactive groups that are capable of reacting together, x being an integer greater than or equal to 2, but other preparation processes may be envisaged.

Hyperbranched polymers are characterized by their degree of polymerization DP = 1-b, b being the percentage of non-terminal functions of B which have not reacted with a group A. Since the condensation is not systematic, unlike for the synthesis of dendrimers (see hereinbelow), the degree of polymerization is less than 100%. A terminal group T on the hyperbranched polymer can be made to react to obtain a particular function at the end of chains.

Several hyperbranched polymers can be combined together, by covalent bonding or another type of bonding, by means of their terminal groups. Such polymers, which are said to be bridged, are included in the definition of the hyperbranched polymers according to the present invention.

Numerous hyperbranched polymers and dendrimers have already been described. Reference may be made, for example, to: D.A. Tomalia et al., Angew. Chem. Int. Engl. 29, 138-175 (1990); N. Ardoin and D. Astruc, Bull. Soc. Chim. Fr. 132, 875-909 (1995); B.l. Voit, Acta Polymer, 46, 87-99 (1995). Such polymers are described in particular in B.l. Voit, Acta Polymer., 46, 87-99 (1995); EP- 682 059; WO-96/14346; WO-96/14345; WO-96/12754. Several hyperbranched polymers can be combined together, by covalent bonding or another type of bonding, by means of their terminal groups.

Such polymers, which are said to be bridged, are included in the definition of the hyperbranched polymers according to the present invention.

“Dendrimers” are macromolecules consisting of monomers which associate by means of an arborescent process around a multifunctional central core.

Dendrimers thus have a fractal (or fractal molecule) structure, consisting of a core, a given number of generations of branches (or wedges), of internal cavities originating from said branches of the molecule, and of terminal functions.

Dendrimers are, structurally, highly branched polymers and oligomers having a well-defined chemical structure.

Dendrimers may be in the form of an assembly of molecules of the same generation, the assembly being referred to as “monodisperse”; they may also be in the form of assemblies of different generations, which are referred to as being “polydisperse”. The definition of dendrimers according to the present invention includes monodisperse dendrimer assemblies as well as polydisperse dendrimer assemblies.

The generations of branches consist of structural units, which are identical for the same generation of branches and which may be identical or different for different generations of branches. All of the junction points of branches of the same generation are located an equal distance from the core; this corresponds to a generation.

The generations of branches extend radially in a geometrical progression from the core. The terminal groups of an n ^th generation dendrimer are the terminal functional groups of the branches of the n ^th generation, referred to as the terminal generation.

The definition of dendrimers given above includes molecules bearing symmetrical branching; it also includes molecules bearing non-symmetrical branching, for instance dendrimers in which the branches are lysine groups, in which the branching of one generation of wedges on the preceding generation takes place on the a and E amines of lysine, which leads to a difference in the length of the wedges of the various branches.

Dendrimers also known as “dense star polymers” or “starburst polymers” or “rod-shaped dendrimers” are included in the present definition of dendrimers. The molecules known as “arborols” and “cascade molecules” are also included in the definition of dendrimers according to the present invention. Moreover, several dendrimers may be combined together, via a covalent bond or another type of bonding, by means of their terminal groups to give species known as “bridged dendrimers” or “dendrimer aggregates”. Such species are included in the definition of dendrimers according to the present invention.

Dendrimers may be in the form of an assembly of molecules of the same generation, the assembly being referred to as “monodisperse”; they may also be in the form of assemblies of different generations, which are referred to as being “polydisperse”. The definition of dendrimers according to the present invention includes monodisperse dendrimer assemblies as well as polydisperse dendrimer assemblies.

According to one embodiment, the polymeric thiol compounds are of formula (ll’B):

POL(SH)n (ll’B) in which formula (ll’B) n represents an integer greater than or equal to 5, preferably ranging from 5 to 5000, more preferentially ranging from 5 to 1000; and POL denotes a carbon-based or silicone-based multivalent (at least pentavalent) polymeric radical, POL also possibly containing one or more heteroatoms such as O, N or S, and/or one or more functions chosen from ester, ketone, amide, urea and carbamate functions, and/or possibly being substituted with one or more linear or branched C1-C10 alkyl or linear or branched C1-C10 alkoxy groups, it being understood that when POL is substituted, the thiol functions may be borne by the substituent(s).

The molar mass of the compounds of formula (ll’B) generally ranges from 500 to 400 000 and preferably from 500 to 150 000.

POL may denote a multivalent radical of homopolymer or copolymer type;

POL may denote a polymeric radical of star, comb, brush or dendritic type. The radical POL may be of natural origin (such as polysaccharides or peptides) or of synthetic origin (such as acrylic polymers, polyesters or polyglycols).

The thiol functions (-SH) may be terminal and/or side groups.

According to a first embodiment, the polymeric thiol compounds of formula (ll’B) are such that POL denotes a hydrocarbon-based polymeric radical.

Examples that may be mentioned include the polymers described in the following articles: Polymers containing groups of biological activity, C.G. Overberger et al., Polytechnic Institute of Brooklyn, http://pac.iupac.org/publications/pac/pdf/1962/pdf/0402x0521 .pdf and Mercaptan-containing polymers, Advances in Polymer Science, volume 15, 1974, pages 61-90. In particular, mention may be made of the polymeric thiol compounds of formula (ll’B), such as poly(vinyl mercaptan), poly(4-mercaptostyrene), poly(vinylbenzyl mercaptan), poly(4- mercaptostyrene)-co-poly(methyl methacrylate), and also polymers containing amide functions in the polymer, such as poly(thiolated hexamethylene adipamide). The polymeric thiol compounds of formula (ll’B) also denote proteins and peptides with thiol units, for instance the structures represented in the following table:

The polymeric thiol compounds of formula (ll’B) also denote the compounds of formula (ll’B) such that POL denotes a radical termed a dendrimer or a branched or hyperbranched polymer, and the thiol groups are terminal groups. As examples, mention may be made of the polymers described in the article Progress in Organic Coatings, volume 63, issue 1 , July 2008, pages 100-109. As an example of a synthesis of such polymers, mention may be made of the synthesis described in said article in which the polymer Boltorn H40 is transformed into a thiol polymer of formula (ll’B) according to the scheme below: The structure of the thiol polymer (ll’B) obtained is given below:

The polymeric thiol compounds of formula (ll’B) may also denote a hyperbranched or dendritic polymer modified with thiol functions, as described in patent application FR 2 761 691. 57 As examples of hyperbranched polymers and dendrimers including thiol functional groups, mention may be made of the hyperbranched polymers and dendrimers including functional groups of formula (X) below: 5 in which formula (X): Y represents an oxygen or sulfur atom or a group NR’; X represents i) an oxygen atom or ii) a group –N(R’)- in which R’ is chosen from a) a hydrogen atom, b) a linear or branched, saturated or unsaturated C ₁ -C ₆ alkyl group, c) a linear or branched, saturated or unsaturated C ₁ -C ₆ monohydroxyalkyl or polyhydroxyalkyl 10 group, d) a C ₁ -C ₆ aminoalkyl group or a polyalkyleneimine group; preferably, X represents -N(R’)- with R’ representing a hydrogen atom or a (C ₁ -C ₄ )alkyl group such as methyl; and A represents a linear, branched or cyclic, saturated or unsaturated (C ₁ -C ₁₂ )alkylene group; this group being optionally interrupted with one or more heteroatoms such as O, S or N and/or optionally substituted with one or more groups chosen from amino (-NH ₂ ), acylamino 15 (-N(H)-C(O)-R) or aminoacyl (RN(H)-C(O)-) in which R represents a linear, branched or cyclic, saturated or unsaturated C ₁ -C ₁₀ alkyl, carboxyl (-C(O)OH) or ester (-C(O)-OR) group in which R represents a linear, branched or cyclic, saturated or unsaturated C ₁ -C ₁₀ alkyl group. Preferably, the polymeric thiol compounds according to the invention are chosen from 20 hyperbranched polymers, and notably polyethyleneimine including at least one group chosen from the groups of formula (X) as defined previously. Preferably, Y represents an oxygen atom. Preferably, the heteroatoms are chosen from oxygen and nitrogen (O and N). Preferably, A is a methylene, ethylene, propylene, methylpropylene, ethylpropylene, 25 tetramethylene, pentamethylene, hexamethylene or phenylene group. Advantageously, A represents a radical corresponding to one of the formulae (a) to (d) below:

in which formulae (a), (b), (c) and (d): R ¹ , R ² , R ³ , R’ ¹ , R’ ² , R’ ³ and R’ ⁴ , R’’’ ¹ and R’’’ ² , which may be identical or different, represent: a hydrogen atom; a linear, branched or cyclic, saturated or unsaturated C ₁ -C ₆ alkyl group; an amino group (-NH ₂ ); a carboxylic acid group (-COOH); a C ₁ -C ₁₀ alkylamino group; a C ₁ - C ₁₀ acylamino group; R’’ ¹ , R’’ ² , R’’ ³ and R’’ ⁴ , which may be identical or different, represent a hydrogen atom or a linear or branched, saturated or unsaturated C ₁ -C ₄ alkyl group; the arrows indicating the positions of the substitutions; and k is an integer, preferentially 0 or 1; represents the point of attachment to the rest of the molecule on the phenylene group in position 1-2, or 1-3, or 1-4; it being understood that the radicals R’’ ₁ , R’’ ₂ , R’’ ₃ and R’’ ₄ are then positioned on the carbon atoms 3, 4, 5, 6, or 2, 4, 5 or 6 or 2, 3, 5, 6, respectively. According to a preferred embodiment of the invention, the polymeric thiol compounds are hyperbranched polymers and dendrimers including functional groups of formula (X) such that A is chosen from: -CH ₂ -CH(CO ₂ H)-NH- and Y represents an oxygen atom; -(CH ₂ ) ₂ -(CH ₃ CONH)CH- and Y represents an oxygen atom; -(CH ₂ ) ₃ - and Y represents an oxygen atom or an NH group. In particular, A is the propylene group -CH ₂ -CH ₂ -CH ₂ - and Y represents an oxygen atom, the compound according to the invention then corresponding to formula (XI) below: in which formula (XI) X is as defined previously; preferably, X represents -N(R’)- with R’ representing a hydrogen atom or a (C ₁ -C ₄ )alkyl group such as methyl. Preferentially, according to the invention, X of formulae (X) and (XI) is chosen from an oxygen atom and an NH group. According to one of the preferred embodiments of the invention, the thiol polymers are as described in FR 2853533, that is to say poly-N-α- and N-ε- lysine and ornithine of formula I, bearing a thiol function, which may be obtained from poly-N-α- and N-ε- lysine and ornithine by reaction with a thiolactone, for instance thiobutyrolactone (dihydrothiophen- 2(3H)-one). According to a preferred embodiment of the invention, the hyperbranched polymers and dendrimers that are useful in the invention include functional groups corresponding to formula (XII): in which formula (XII): p is different from p’ and p and p’ are equal to 0 or 1; n is 3 or 4; if p’ is equal to 0, then the neighbouring NH is engaged in an N-ε polymerization; if p is equal to 0, then the neighbouring NH is engaged in an N-α polymerization; if p or p’ is equal to 1, then R or R’ represents -B-SH, with B representing a saturated or unsaturated, linear or branched C ₁ -C ₃₀ hydrocarbon-based chain which may be interrupted with one or more heteroatoms or groups, alone or in combination, such as: -N(R ¹ )-, -O-, -S(O) _r -, -C(O)-, -C(S)- or -C(NR ¹ )-, with r being equal to 0, 1 or 2, and/or with one or more 5-, 6- or 7-membered aryl, heteroaryl, cycloalkyl or heterocycloalkyl which may be substituted with one or more halogen atoms or groups from among: hydroxyl, amino, carboxyl, (di)(C ₁ -C ₈ )alkylamino, (C ₁ -C ₈ )acylamino, (C ₁ -C ₈ )acyloxy, (C ₁ - C ₈ )alkyloxycarbonylamino, (C ₁ -C ₈ )alkylaminocarbonyloxy or (C ₁ -C ₈ )alkylaminocarbonyl; given that R or R’ may also, in part only, represent a hydrogen atom, and/or –C(NH)- and salts thereof and/or –C(NH)-N(H)-C(NH)-NH ₂ and salts thereof R ₁ represents a hydrogen atom or a (C ₁ -C ₈ )alkyl, (C ₁ -C ₈ )acyl, (C ₁ -C ₈ )alkyloxycarbonyl, (C ₁ - C ₈ )alkylaminocarbonyl or halo group; B may also represent an optionally substituted 5-, 6- or 7-membered aryl, heteroaryl, cycloalkyl or heterocycloalkyl group; m represents an integer ranging from 3 to 10 000.

Preferably, the degree of thiol function grafting will be greater than or equal to 1%.

Advantageously, the poly N-a- and N-E- lysine and ornithine corresponding to formula (XII) have: 5 < m < 1000.

The term “theoretical degree of thiol function grafting” represents the theoretical percentage of lysine or ornithine units bearing the thiol function in the compound of formula (XII).

Examples of hyperbranched polymers that may be mentioned most particularly include hyperbranched thiolated polyethyleneimines, such as those described in patent application EP 103 759 with a molecular molar mass ranging from 30x10 ⁴ to 50x10 ⁴ .

These polymers are prepared according to methods that are conventional to those skilled in the art, such as the methods described in French patent application FR 2 761 691 and EP 1 037 938.

According to a particular embodiment of the invention, the dendrimers and branched or hyperbranched polymers bear thiol terminal groups, such as the Boltorn™ dendritic polythiols from the company BASF esterified with compounds such as thioglycolic acid and described in the literature.

Polymers such as polypropylene ether glycol bis(P-mercaptopropionate) may also be used in the invention. They are prepared via the methods known to those skilled in the art. Mention may be made, for example, of the preparation method by esterification reaction of polypropylene ether glycol (e.g., Pluracol P201 , Wyandotte Chemical Corp.) and P-mercaptopropionic acid.

According to a particular embodiment of the invention, the thiol polymers are polyethoxylated polymers of formula (XIII):

in which formula (XIII): R ₁ , R ₂ and R ₃ , which may be identical or different, represent a thio(C ₁ -C ₆ )alkyl group; R ₄ represents a hydrogen atom or a group from among: hydroxyl, thiol, amino or (C ₁ - C ₆ )alkyl, preferably (C ₁ -C ₄ )alkyl such as ethyl; X ₁ and X ₂ , which may be identical or different, preferably identical, represent an oxygen or sulfur atom, or amino, preferably oxygen; m, n and l, which may be identical or different, represent an integer greater than or equal to 1. The thiol polymer compounds of formula (XIII) are commercially available. Mention may be made, for example, of the products Thiocure® from the company Bruno Brock, Thiocure® ETTMP 1300 (Ethoxylated-Trimethylolpropane Tri-3-Mercaptopropionate (CAS# 345352- 19-4) and Thiocure® ETTMP 700 (Ethoxylated-Trimethylolpropane Tri-3- Mercaptopropionate (CAS# 345352-19-4). According to a particular embodiment of the invention, the polythiol polymers are mineral polymers. Mention may be made of polythiol silicones and polythiol silicas. (Poly)carbonyl compounds The crosslinking agent(s) may be chosen from d’) (poly)carbonyl compounds. In particular, the (poly)carbonyl compounds are chosen from terephthalaldehyde, 5,5- dimethyl-1,3-cyclohexanedione, phenylglyoxal, isophthalaldehyde, 4-acetylbenzaldehyde, 4,4-diformyltriphenylamine, 2-acetylbenzaldehyde, 3-(2-furoyl)quinoline-2-carboxaldehyde, 3-(2-furoyl)quinoline-2-carboxaldehyde, 3-acetylbenzaldehyde, 9-(2-ethylhexyl)carbazole- 3,6-dicarboxaldehyde, phthaldialdehyde, 1,3-cyclohexanedione, 4,4’- biphenyldicarboxaldehyde, benzene-1,3,5-tricarboxaldehyde, oxidized inulin, and mixtures thereof.

In particular, the (poly)carbonyl compounds are chosen from terephthalaldehyde, 5,5- dimethyl-1,3-cyclohexanedione, phenylglyoxal, isophthalaldehyde, 4-acetylbenzaldehyde, 4,4-diformyltriphenylamine, 2-acetylbenzaldehyde, 3-(2-furoyl)quinoline-2-carboxaldehyde, 3-(2-furoyl)quinoline-2-carboxaldehyde, 3-acetylbenzaldehyde, 9-(2-ethylhexyl)carbazole- 3,6-dicarboxaldehyde, phthaldialdehyde, 1,3-cyclohexanedione, 4,4’- biphenyldicarboxaldehyde, benzene-1,3,5-tricarboxaldehyde, oxidized inulin, and terephthalaldehyde, and mixtures thereof, preferably terephthalaledhyde.

According to this embodiment, the (poly)carbonyl compound is associated in its implementation with an amine catalyst as described, for example, in the articles Progress in coating 129, 21-25 (2019) and Progress in coating 135, 510-516 (2019); preferably, the amine catalyst(s) are chosen from piperidine, DMAP (dimethylaminopyridine), DBU (1 ,8- diazabicyclo[5.4.0]undec-7-ene), DABCO (1,4-diazabicyclo[2.2.2]octane) and DBN (1,5- diazabicyclo[4.3.0]non-5-ene), more preferentially chosen from DBU (1 ,8- diazabicyclo[5.4.0]undec-7-ene), DABCO (1,4-diazabicyclo[2.2.2]octane) and DBN (1,5- diazabicyclo[4.3.0]non-5-ene), and in particular the catalyst is DBU (1 ,8- diazabicyclo[5.4.0]undec-7-ene).

The crosslinking agent(s) may be chosen from e’) (poly)acrylate compounds.

More particularly, the (poly)acrylate compounds are chosen from 1,3-butanediol diacrylate, 1 ,4-butanediol diacrylate, bis(trimethylolpropane) tetraacrylate, glyceryl 1,3-diglycerolate diacrylate, glyceryl propoxylate (1PO/OH) triacrylate, 1,6-hexanediol diacrylate, 1,6- hexanediol ethoxylate diacrylate, hydroxypivalyl hydroxypivalate, neopentyl glycol diacrylate, neopentyl glycol propoxylate (1 PO/OH) diacrylate, pentaerythrityl tetraacrylate, pentaerythrityl triacrylate, polypropylene glycol) diacrylate, tricyclo[5.2.1.0 ² ’ ⁶ ]decanedimethanol diacrylate, trimethylolpropane ethoxylate (1 EO/OH) methyl ether diacrylate, trimethylolpropane propoxylate triacrylate, trimethylolpropane triacrylate, tri(propylene glycol) diacrylate, tris[2-(acryloyloxy)ethyl] isocyanurate, N,N’- methylenebis(acrylamide), trimethylolpropane triacrylate, methylenebis(acrylamide), or mixtures of these compounds.

More particularly, the (poly)acrylate compound is trimethylolpropane triacrylate.

According to this embodiment, the (poly)acrylate compound is associated in its implementation with at least one amine catalyst as described, for example, in the articles Progress in coating 129, 21-25 (2019) and Progress in coating 135, 510-516 (2019); preferably, the amine catalyst(s) are chosen from piperidine, DMAP (dimethylaminopyridine), DBU (1 ,8-diazabicyclo[5.4.0]undec-7-ene), DABCO (1 ,4- diazabicyclo[2.2.2]octane) and DBN (1 ,5-diazabicyclo[4.3.0]non-5-ene), more preferentially chosen from DBU (1 ,8-diazabicyclo[5.4.0]undec-7-ene), DABCO (1 ,4- diazabicyclo[2.2.2]octane) and DBN (1 ,5-diazabicyclo[4.3.0]non-5-ene), and preferably the catalyst is DBU (1 ,8-diazabicyclo[5.4.0]undec-7-ene).

According to a preferred embodiment, the crosslinking agent(s) are chosen from: a’) amine compounds chosen from polyamine compounds containing at least two primary and/or secondary amine groups, preferably chosen from chitosans, bis-cetearyl amodimethicone and mixtures thereof; and/or b’) organic or mineral, polymeric or non-polymeric, preferably organic or silicone-based, hydroxylated compounds chosen from polyhydroxylated compounds containing at least two hydroxyl groups, preferably chosen from polydimethylsiloxanes bearing hydroxyl terminal functions; and/or c’) organic or mineral, polymeric or non-polymeric, preferably organic or silicone-based, thiol compounds chosen from polythiol compounds containing at least two thiol groups, preferably chosen from polydimethylsiloxanes including at least two thiol groups.

According to a more preferred embodiment, the crosslinking agent(s) are chosen from: a’) amine compounds chosen from polyamine compounds containing at least two primary and/or secondary amine groups, preferably chosen from chitosans, bis-cetearyl amodimethicone and mixtures thereof; and/or c’) organic or mineral, polymeric or non-polymeric, preferably organic or silicone-based, thiol compounds chosen from polythiol compounds containing at least two thiol groups, preferably chosen from polydimethylsiloxanes including at least two thiol groups.

Colouring agent(s)

The process according to the invention comprises step iii) of applying to the keratin fibres one or more colouring agents chosen from direct dyes, oxidation dyes, pigments and mixtures thereof, preferably from direct dyes, pigments and mixtures thereof, more preferentially from pigments.

The term “colouring agent” means an oxidation dye, a direct dye or a pigment.

The term “oxidation dye” means an oxidation dye precursor chosen from oxidation bases and couplers. Oxidation bases and couplers are colourless or sparingly coloured compounds, which, via a condensation reaction in the presence of an oxidizing agent, give a coloured species;

The term “direct dye” means a natural and/or synthetic dye, including in the form of an extract or extracts, other than oxidation dyes. These are coloured compounds that will spread superficially on the fibre. They may be ionic or nonionic, i.e. anionic, cationic, neutral or nonionic.

Direct dyes and/or oxidation dyes

The colouring agent(s) used in the process according to the invention may be chosen from direct dyes, oxidation dyes and mixtures thereof, preferably from direct dyes.

The oxidation dyes are generally chosen from one or more oxidation bases, optionally combined with one or more coupling agents.

By way of example, the oxidation bases may be chosen from para-phenylenediamines, bis(phenyl)alkylenediamines, para-aminophenols, ortho-aminophenols and heterocyclic bases and the corresponding addition salts, optionally combined with coupling agents; they may in particular be chosen from meta-phenylenediamines, meta-aminophenols, metadiphenols, naphthalene-based coupling agents and heterocyclic coupling agents and also the corresponding addition salts.

By way of example, the direct dyes may notably be chosen from azo direct dyes; (poly)methine dyes such as cyanines, hemicyanines and styryls; carbonyl dyes; azine dyes; nitro(hetero)aryl dyes; tri(hetero)arylmethane dyes; porphyrin dyes; phthalocyanine dyes and natural direct dyes, alone or in the form of mixtures. The direct dyes may be anionic, cationic or neutral;

The natural direct dyes may notably be chosen from hennotannic acid, juglone, alizarin, purpurin, carminic acid, kermesic acid, purpurogallin, protocatechaldehyde, indigo, isatin, curcumin, spinulosin, apigenidin and orcein, and also extracts or decoctions containing these natural dyes.

The colouring agent(s) chosen from direct dyes, oxidation dyes and mixtures thereof more particularly represent from 0.001% to 10% and preferably from 0.005% to 5% by weight relative to the total weight of the composition comprising them. Pigments

The colouring agent(s) used in the process according to the invention are preferably chosen from pigments.

The term “pigment” refers to any pigment that gives colour to keratin fibres. The solubility of the pigments in water at 25°C and at atmospheric pressure (760 mmHg) is less than 0.05% by weight, and preferably less than 0.01 %.

They are white or coloured solid particles which are naturally insoluble in the hydrophilic and lipophilic liquid phases usually employed in cosmetics or which are rendered insoluble by formulation in the form of a lake, where appropriate. More particularly, the pigments have little or no solubility in aqueous-alcoholic media.

The pigments that may be used are notably chosen from the organic and/or mineral pigments known in the art, notably those described in Kirk-Othmer’s Encyclopedia of Chemical Technology and in Ullmann’s Encyclopedia of Industrial Chemistry. Pigments that may notably be mentioned include organic and mineral pigments such as those defined and described in Ullmann’s Encyclopedia of Industrial Chemistry “Pigments, organic”, 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 10.1002/14356007.a20 371 and ibid, “Pigments, Inorganic, 1. General” 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheiml 0.1002/14356007. a20_243.pub3.

These pigments may be in pigment powder or paste form. They may be coated or uncoated. The pigments may be chosen, for example, from mineral pigments, organic pigments, lakes, pigments with special effects such as nacres or glitter flakes, and mixtures thereof.

The pigment may be a mineral pigment. The term “mineral pigment” refers to any pigment that satisfies the definition in Ullmann’s encyclopaedia in the chapter on inorganic pigments. Among the mineral pigments that are useful in the present invention, mention may be made of iron oxides, chromium oxides, manganese violet, ultramarine blue, chromium hydrate, ferric blue and titanium oxide.

The pigment may be an organic pigment. The term “organic pigment” refers to any pigment that satisfies the definition in Ullmann’s encyclopaedia in the chapter on organic pigments. The organic pigment can in particular be chosen from nitroso, nitro, azo, xanthene, quinoline, anthraquinone, phthalocyanine, of metal complex type, isoindolinone, isoindoline, quinacridone, perinone, perylene, diketopyrrolopyrrole, thioindigo, dioxazine, triphenylmethane or quinophthalone compounds.

In particular, the white or coloured organic pigments may be chosen from carmine, carbon black, aniline black, azo yellow, quinacridone, phthalocyanine blue, sorghum red, the blue pigments codified in the Colour Index under the references Cl 42090, 69800, 69825, 73000, 74100, 74160, the yellow pigments codified in the Colour Index under the references Cl 11680, 11710, 15985, 19140, 20040, 21100, 21108, 47000, 47005, the green pigments codified in the Colour Index under the references Cl 61565, 61570, 74260, the orange pigments codified in the Colour Index under the references Cl 11725, 15510, 45370, 71105, the red pigments codified in the Colour Index under the references Cl 12085, 12120, 12370, 12420, 12490, 14700, 15525, 15580, 15620, 15630, 15800, 15850, 15865, 15880, 17200, 26100, 45380, 45410, 58000, 73360, 73915, 75470, the pigments obtained by oxidative polymerization of indole or phenolic derivatives as described in patent FR 2 679 771.

According to a particular embodiment of the invention, the pigment(s) used are pigment pastes of organic pigments such as the products sold by the company Hoechst under the name:

- Cosmenyl Yellow 10G: Yellow 3 pigment (Cl 11710);

- Cosmenyl Yellow G: Yellow 1 pigment (Cl 11680);

- Cosmenyl Orange GR: Orange 43 pigment (Cl 71105);

- Cosmenyl Red R: Red 4 pigment (Cl 12085);

- Cosmenyl Carmine FB: Red 5 pigment (Cl 12490);

- Cosmenyl Violet RL: Violet 23 pigment (Cl 51319);

- Cosmenyl Blue A2R: Blue 15.1 pigment (Cl 74160);

- Cosmenyl Green GG: Green 7 pigment (Cl 74260);

- Cosmenyl Black R: Black 7 pigment (Cl 77266).

The pigments in accordance with the invention may also be in the form of composite pigments, as described in patent EP 1 184 426. These composite pigments may be composed notably of particles including:

- a mineral core,

- at least one binder for fixing the organic pigments to the core, and

- at least one organic pigment at least partially covering the core.

The term “lake” refers to dyes adsorbed onto insoluble particles, the assembly thus obtained remaining insoluble during use. The mineral substrates onto which the dyes are adsorbed are, for example, alumina, silica, calcium sodium borosilicate or calcium aluminium borosilicate and aluminium. Among the organic dyes, mention may be made of cochineal carmine.

Examples of lakes that may be mentioned include the products known under the following names: D & C Red 21 (Cl 45 380), D & C Orange 5 (Cl 45 370), D & C Red 27 (Cl 45410), D & C Orange 10 (Cl 45 425), D & C Red 3 (Cl 45 430), D & C Red 7 (Cl 15 850:1), D & C Red 4 (Cl 15 510), D & C Red 33 (Cl 17 200), D & C Yellow 5 (Cl 19 140), D & C Yellow 6 (Cl 15 985), D & C Green 5 (Cl 61 570), D & C Yellow 10 (Cl 77 002), D & C Green 3 (Cl 42 053), D & C Blue 1 (Cl 42 090).

The pigment(s) may also be pigments with special effects.

The term “pigments with special effects” means pigments that generally create a coloured appearance (characterized by a certain shade, a certain vivacity and a certain level of luminance) that is non-uniform and that changes as a function of the conditions of observation (light, temperature, angles of observation, etc.). They thereby differ from coloured pigments, which afford a standard uniform opaque, semi-transparent or transparent shade.

Several types of pigments with special effects exist: those with a low refractive index, such as fluorescent, photochromic or thermochromic pigments, and those with a higher refractive index, such as nacres or glitter flakes.

Examples of pigments with special effects that may be mentioned include nacreous pigments such as titanium mica coated with an iron oxide, mica coated with an iron oxide, mica coated with bismuth oxychloride, titanium mica coated with chromium oxide, titanium mica coated with an organic dye notably of the abovementioned type, and also nacreous pigments based on bismuth oxychloride. They may also be mica particles, at the surface of which are superposed at least two successive layers of metal oxides and/or of organic dyestuffs.

The nacres can more particularly have a yellow, pink, red, bronze, orangey, brown, gold and/or coppery colour or tint.

As illustrations of nacres that may be used in the context of the present invention, mention may notably be made of the gold-coloured nacres sold notably by the company Engelhard under the name Gold 222C (Cloisonne), Sparkle gold (Timica), Gold 4504 (Chromalite) and Monarch gold 233X (Cloisonne); the bronze nacres sold notably by the company Merck under the names Bronze fine (17384) (Colorona) and Bronze (17353) (Colorona), by the company Eckart under the name Prestige Bronze and by the company Engelhard under the name Super bronze (Cloisonne); the orange nacres sold notably by the company Engelhard under the names Orange 363C (Cloisonne) and Orange MCR 101 (Cosmica) and by the company Merck under the names Passion orange (Colorona) and Matte orange (17449) (Microna); the brown-tinted nacres sold notably by the company Engelhard under the names Nu-antique copper 340XB (Cloisonne) and Brown CL4509 (Chromalite); the nacres with a copper tint sold notably by the company Engelhard under the name Copper 340A (Timica) and by the company Eckart under the name Prestige Copper; the nacres with a red tint sold notably by the company Merck under the name Sienna fine (17386) (Colorona); the nacres with a yellow tint sold notably by the company Engelhard under the name Yellow (4502) (Chromalite); the red-coloured nacres with a golden tint sold notably by the company Engelhard under the name Sunstone G012 (Gemtone); the black nacres with a golden tint sold notably by the company Engelhard under the name Nu-antique bronze 240 AB (Timica); the blue nacres sold notably by the company Merck under the names Matte blue (17433) (Microna), Dark Blue (117324) (Colorona); the white nacres with a silvery tint sold notably by the company Merck under the name Xirona Silver; and the golden-green pinkishorange nacres sold notably by the company Merck under the name Indian summer (Xirona), and mixtures thereof.

In addition to nacres on a mica support, multilayer pigments based on synthetic substrates such as alumina, silica, sodium calcium borosilicate or calcium aluminium borosilicate, and aluminium, may be envisaged.

Mention may also be made of pigments with an interference effect which are not attached to a substrate, such as liquid crystals (Helicones HC from Wacker) or interference holographic glitter flakes (Geometric Pigments or Spectra f/x from Spectratek). Pigments with special effects also comprise fluorescent pigments, whether these are substances that are fluorescent in daylight or that produce an ultraviolet fluorescence, phosphorescent pigments, photochromic pigments, thermochromic pigments and quantum dots, sold, for example, by the company Quantum Dots Corporation.

The variety of pigments that may be used in the present invention makes it possible to obtain a wide range of colours, and also particular optical effects such as metallic effects or interference effects.

The size of the pigment(s) used in the process according to the present invention generally ranges from 10 nm to 200 μm, preferably from 20 nm to 80 μm and more preferentially from 30 nm to 50 μm.

The pigments may be dispersed in the composition comprising them by means of a dispersant.

The term “dispersant” refers to a compound which can protect the dispersed particles from agglomerating or flocculating. This dispersant may be a surfactant, an oligomer, a polymer or a mixture of several thereof, bearing one or more functionalities with strong affinity for the surface of the particles to be dispersed. In particular, they may become physically or chemically attached to the surface of the pigments. These dispersants also contain at least one functional group that is compatible with or soluble in the continuous medium. Said agent may be charged: it may be anionic, cationic, zwitterionic or neutral.

According to a particular embodiment of the invention, the dispersants used are chosen from esters of 12- hydroxy stearic acid, more particularly, and of Cs to C20 fatty acid and of polyols such as glycerol or diglycerol, such as poly(12-hydroxystearic acid) stearate with a molecular weight of approximately 750 g/mol, such as the product sold under the name Solsperse 21 000 by the company Avecia, polyglyceryl-2 dipolyhydroxystearate (CTFA name) sold under the reference Dehymyls PGPH by the company Henkel, or polyhydroxystearic acid such as the product sold under the reference Arlacel P 100 by the company Uniqema, and mixtures thereof.

As other dispersants that may be used in the compositions of the invention, mention may be made of quaternary ammonium derivatives of polycondensed fatty acids, for instance Solsperse 17 000 sold by the company Avecia, and polydimethylsiloxane/oxypropylene mixtures such as those sold by the company Dow Corning under the references DC2-5185 and DC2-5225 C.

The pigments used in the process according to the invention may be surface-treated with an organic agent.

Thus, the pigments surface-treated beforehand that are useful in the context of the invention are pigments which have been completely or partially subjected to a surface treatment of chemical, electronic, electrochemical, mechanochemical or mechanical nature with an organic agent, such as those described notably in Cosmetics and Toiletries, February 1990, Vol. 105, pages 53-64, before being dispersed in the composition in accordance with the invention. These organic agents may be chosen, for example, from amino acids; waxes, for example carnauba wax and beeswax; fatty acids, fatty alcohols and derivatives thereof, such as stearic acid, hydroxystearic acid, stearyl alcohol, hydroxystearyl alcohol and lauric acid and derivatives thereof; anionic surfactants; lecithins; sodium, potassium, magnesium, iron, titanium, zinc or aluminium salts of fatty acids, for example aluminium stearate or laurate; metal alkoxides; polysaccharides, for example chitosan, cellulose and derivatives thereof; polyethylene; (meth)acrylic polymers, for example polymethyl methacrylates; polymers and copolymers containing acrylate units; proteins; alkanolamines; silicone compounds, for example silicones, polydimethylsiloxanes, alkoxysilanes, alkylsilanes and siloxysilicates; organofluorine compounds, for example perfluoroalkyl ethers; fluorosilicone compounds.

The surface-treated pigments used in the process according to the invention may also have been treated with a mixture of these compounds and/or may have undergone several surface treatments.

The surface-treated pigments that are useful in the context of the present invention may be prepared according to surface-treatment techniques that are well known to those skilled in the art, or may be commercially available as is.

Preferably, the surface-treated pigments are coated with an organic layer.

The organic agent with which the pigments are treated may be deposited on the pigments by evaporation of solvent, chemical reaction between the molecules of the surface agent or creation of a covalent bond between the surface agent and the pigments.

The surface treatment may thus be performed, for example, by chemical reaction of a surface agent with the surface of the pigments and creation of a covalent bond between the surface agent and the pigments or the fillers. This method is notably described in patent US 4 578 266.

An organic agent covalently bonded to the pigments will preferably be used.

The agent for the surface treatment may represent from 0.1% to 50% by weight, preferably from 0.5% to 30% by weight and even more preferentially from 1 % to 10% by weight relative to the total weight of the surface-treated pigments.

Preferably, the surface treatments of the pigments are chosen from the following treatments:

- a PEG-silicone treatment, for instance the AQ surface treatment sold by LCW;

- a chitosan treatment, for instance the CTS surface treatment sold by LCW;

- a triethoxycaprylylsilane treatment, for instance the AS surface treatment sold by LCW;

- a methicone treatment, for instance the SI surface treatment sold by LCW;

- a dimethicone treatment, for instance the Covasil 3.05 surface treatment sold by LCW;

- a dimethicone/trimethyl siloxysilicate treatment, for instance the Covasil 4.05 surface treatment sold by LCW;

- a lauroyllysine treatment, for instance the LL surface treatment sold by LCW;

- a lauroyllysine dimethicone treatment, for instance the LL/SI surface treatment sold by LCW;

- a magnesium myristate treatment, for instance the MM surface treatment sold by LCW;

- an aluminium dimyristate treatment, for instance the Ml surface treatment sold by Miyoshi; - a perfluoropolymethyl isopropyl ether treatment, for instance the FHC surface treatment sold by LCW;

- an isostearyl sebacate treatment, for instance the HS surface treatment sold by Miyoshi;

- a disodium stearoyl glutamate treatment, for instance the NAI surface treatment sold by Miyoshi;

- a dimethicone/disodium stearoyl glutamate treatment, for instance the SA/NAI surface treatment sold by Miyoshi;

- a perfluoroalkyl phosphate treatment, for instance the PF surface treatment sold by Daito;

- an acrylate/dimethicone copolymer and perfluoroalkyl phosphate treatment, for instance the FSA surface treatment sold by Daito;

- a polymethylhydrogenosiloxane/perfluoroalkyl phosphate treatment, for instance the FS01 surface treatment sold by Daito;

- a lauroyllysine/aluminium tristearate treatment, for instance the LL-StAI surface treatment sold by Daito;

- an octyltriethylsilane treatment, such as the OTS surface treatment sold by Daito;

- an octyltriethylsilane/perfluoroalkyl phosphate treatment, such as the FOTS surface treatment sold by Daito;

- an acrylate/dimethicone copolymer treatment, for instance the ASC surface treatment sold by Daito;

- an isopropyl titanium triisostearate treatment, for instance the ITT surface treatment sold by Daito;

- a microcrystalline cellulose and carboxymethylcellulose treatment, for instance the AC surface treatment sold by Daito;

- a cellulose treatment, for instance the C2 surface treatment sold by Daito;

- an acrylate copolymer treatment, for instance the APD surface treatment sold by Daito;

- a perfluoroalkyl phosphate/isopropyl titanium triisostearate treatment, for instance the PF + ITT surface treatment sold by Daito.

The pigments used in the process according to the invention may be surface-treated with an organic agent.

The compositions used in the process according to the present invention may also comprise one or more pigments that are not surface-treated.

According to a particular embodiment of the invention, the pigment(s) are mineral pigments. According to another particular embodiment of the invention, the pigment(s) are chosen from nacres.

According to a particular embodiment of the invention, the dispersant is present with organic or mineral pigments in submicron-sized particulate form in the composition comprising them.

The term “submicron” or “submicronic” refers to pigments having a particle size that has been micronized by a micronization method and having a mean particle size of less than a micrometre (μm), in particular ranging from 0.1 to 0.9 μm and preferably ranging from 0.2 to 0.6 μm.

According to one embodiment, the dispersant and the pigment(s) are present in an amount (dispersantpigment) ranging from 0.5:1 to 2:1 , particularly ranging from 0.75:1 to 1.5:1 or better still ranging from 0.8:1 to 1.2:1.

According to a particular embodiment, the dispersant is suitable for dispersing the pigments and is compatible with a condensation-curable formulation.

The term “compatible” means, for example, that said dispersant is miscible in the oily phase of the composition containing the pigment(s), and it does not retard or reduce the curing. The dispersant is preferably cationic.

The dispersant(s) may therefore have a silicone backbone, such as silicone polyether and dispersants of amino silicone type. Among the suitable dispersants that may be mentioned are:

- amino silicones, i.e. silicones comprising one or more amino groups such as those sold under the names and references: BYK LPX 21879 by BYK, GP-4, GP-6, GP-344, GP-851 , GP-965, GP-967 and GP-988-1 , sold by Genesee Polymers,

- silicone acrylates such as Tego® RC 902, Tego® RC 922, Tego® RC 1041 and Tego® RC 1043, sold by Evonik,

- polydimethylsiloxane (PDMS) silicones bearing carboxyl groups such as X-22162 and X- 22370 by Shin-Etsu, epoxy silicones such as GP-29, GP-32, GP-502, GP-504, GP-514, GP-607, GP-682, and GP-695 by Genesee Polymers, or Tego® RC 1401 , Tego® RC 1403 and Tego® RC 1412 by Evonik. According to a particular embodiment, the dispersant(s) are of amino silicone type and are positively charged.

Mention may also be made of dispersants bearing chemical groups that are capable of reacting with the reagents of the oily phase and are thus capable of improving the 3D network formed from the amino silicones. For example, dispersants of epoxy silicone pigments can react chemically with the amino silicone prepolymer amino group(s) to increase the cohesion of the aminosilicone film comprising the pigment(s).

Preferably, the pigment(s) used in the process of the invention are chosen from nacres, carbon black, such as Black 2, iron oxides, notably red, brown or black iron oxides, and micas coated with iron oxide, triarylmethane pigments, notably blue and violet triarylmethane pigments, such as Blue 1 Lake, azo pigments, notably red azo pigments, such as D&C Red 7, alkali metal or alkaline-earth metal salts of lithol red, such as the calcium salt of lithol red B, and mixtures thereof.

Metal compound(s)

The process according to the invention comprises step iv) of applying to the keratin fibres one or more metal compounds chosen from: a) metal salts chosen from alkali metal salts, alkaline-earth metal salts such as magnesium salts, transition metal salts, post-transition metal salts such as aluminium or tin salts, metalloid salts such as boron salts, hydrates thereof and mixtures thereof; and/or

P) metal alkoxides of formulae (la), (lb), (Ic) and (Id) below and mixtures thereof:

M-(ORi) _n (la)

R-M-(ORi) _n -i (lb)

(RlO) _n -1-M-R”-M’-(ORl’)n- ₁ (Ic)

R-M(R’)-(ORi) _n -2 (Id) in which formulae (la), (lb), (Ic) and (Id):

- M and M’, which may be identical or different, represent an atom chosen from alkaline- earth metals, transition metals such as titanium or zirconium, metals of the lanthanide family, post-transition metals such as aluminium or tin and metalloids such as boron; preferably transition metals such as titanium or zirconium and post-transition metals such as aluminium;

- n and n’ respectively represent the valencies of the atoms represented by M and M’;

- Ri and R’i, which may be identical or different, represent a linear or branched, saturated or unsaturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 1 to 6 carbon atoms, said hydrocarbon-based group being optionally interrupted with 1 to 20 heteroatoms chosen from O, N, S and P, notably O or N; and/or said hydrocarbonbased group being optionally substituted with one or more hydroxyl or carbonyl groups;

- R and R’, which may be identical or different, represent a hydrogen atom or a linear, branched or cyclic, saturated or unsaturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 2 to 20 carbon atoms, optionally interrupted with 1 to 20 heteroatoms chosen from O, N, S and/or P, notably O or N, and/or said hydrocarbon-based group being optionally substituted with one or more hydroxyl or carbonyl groups;

- R” represents -O-, -NR2-, -S- or a linear, cyclic or branched, saturated or unsaturated divalent hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 2 to 20 carbon atoms, optionally interrupted with 1 to 20 heteroatoms chosen from O, N, S and P, notably O or N, with R2 representing a linear, cyclic or branched, saturated or unsaturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 2 to 20 carbon atoms.

Metal salts

The metal compound(s) may be chosen from a) metal salts chosen from alkali metal salts, alkaline-earth metal salts such as magnesium salts, transition metal salts, post-transition metal salts such as aluminium or tin salts, metalloid salts such as boron salts, hydrates thereof and mixtures thereof.

The term “metal salt’ means a salt resulting notably from the action of an acid on a metal, in particular a transition metal, post-transition metal, metalloid or alkali or alkaline-earth metal.

Preferably, the metal salts are chosen from post-transition metal salts such as aluminium salts, hydrates thereof and mixtures thereof.

The metal salts may be in the form of hydrates.

The metal salts may be mineral or organic salts.

The term “organic metal salt’ means a salt resulting notably from the action of an organic acid on a metal, in particular transition metals, post-transition metals, metalloids, or alkaline or alkaline-earth metals, preferably resulting from the action of a carboxylic acid on a metal. Preferably, the metal salts are chosen from organic metal salts, hydrates thereof, and mixtures thereof.

The term “inorganic metal salt’ means a salt resulting notably from the action of an inorganic acid on a metal, in particular a transition metal, a post-transition metal, a metalloid or an alkali or alkaline-earth metal. The term “inorganic acid” means an acid which does not include any carbon atoms, apart from carbonic acid.

According to a particular embodiment of the invention, the mineral metal salts may be chosen from halides such as chlorides, fluorides, iodides and bromides, carbonates, sulfates, phosphates, nitrates and perchlorates, hydrates thereof, and mixtures thereof.

Metal (poly) (hydroxy) (C-i-Ce) alkyl carboxylates

According to a more particular embodiment, the metal salts are organometallic salts derived from a carboxylic acid.

More particularly, the organometallic salts are chosen from metal (poly)(hydroxy)(Ci- C6)alkylcarboxylates of alkali metals, alkaline-earth metals, transition metals, and posttransition metals such as aluminium.

By the term “metal (poly)(hydroxy)(Ci-C6)alkylcarboxylate” it is understood that the (Ci- Ce)alkyl group is optionally substituted with one or more hydroxyl groups. Preferably, the metal (poly)(hydroxy)(Ci-C6)alkylcarboxylate represents R ^a -C(O)-OM with M representing a transition metal such as titanium (Ti), or else a post-transition metal such as aluminium (Al), and R ^a represents a linear or branched (Ci-Ce)alkyl group optionally substituted with at least one hydroxyl group.

According to a preferred embodiment, the metal salts are organic, preferably chosen from citrates, lactates, glycolates, gluconates, acetates, propionates, fumarates, oxalates, glycinates, tartrates, acetylacetonates, hydrates thereof, and mixtures thereof, more preferentially from basic aluminium acetate, aluminium oxalate, hydrated or non-hydrated aluminium citrate, aluminium lactate, aluminium glycinate, aluminium acetylacetonate and mixtures thereof.

According to a more preferred embodiment, the metal salts are chosen from acetates, lactates, acetylacetonates, and mixtures thereof, preferably from aluminium acetate, aluminium lactate, aluminium acetylacetonate, and mixtures thereof, more preferentially from basic aluminium acetate, aluminium lactate, aluminium acetylacetonate, and mixtures thereof.

Metal alkoxides

The metal compound(s) may be chosen from ) the metal alkoxides of formulae (la), (lb), (Ic) and (Id) below and mixtures thereof:

M-(ORi) _n (la) R-M-(ORi) _n -i (lb)

(RlO) _n -1-M-R”-M’-(ORl’)n- ₁ (Ic)

R-M(R’)-(0Ri) _n -2 (Id) in which formulae (la), (lb), (Ic) and (Id):

- M and M’, which may be identical or different, represent an atom chosen from alkaline- earth metals, transition metals such as titanium or zirconium, metals of the lanthanide family, post-transition metals such as aluminium or tin and metalloids such as boron; preferably transition metals such as titanium or zirconium and post-transition metals such as aluminium;

- n and n’ respectively represent the valencies of the atoms represented by M and M’;

- Ri and R’i, which may be identical or different, represent a linear or branched, saturated or unsaturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 1 to 6 carbon atoms, said hydrocarbon-based group being optionally interrupted with 1 to 20 heteroatoms chosen from O, N, S and P, notably O or N; and/or said hydrocarbonbased group being optionally substituted with one or more hydroxyl or carbonyl groups;

- R and R’, which may be identical or different, represent a hydrogen atom or a linear, branched or cyclic, saturated or unsaturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 2 to 20 carbon atoms, optionally interrupted with 1 to 20 heteroatoms chosen from O, N, S and/or P, notably O or N, and/or said hydrocarbon-based group being optionally substituted with one or more hydroxyl or carbonyl groups;

- R” represents -O-, -NR ₂ -, -S- or a linear, cyclic or branched, saturated or unsaturated divalent hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 2 to 20 carbon atoms, optionally interrupted with 1 to 20 heteroatoms chosen from O, N, S and P, notably O or N, with R ₂ representing a linear, cyclic or branched, saturated or unsaturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 2 to 20 carbon atoms.

Preferably, M and M’, which may be identical or different, represent an atom chosen from transition metals such as titanium or zirconium or alkaline-earth metals such as magnesium, more preferentially chosen from transition metals such as titanium or zirconium, even more preferentially titanium.

Preferably, the metal compound(s) are chosen from the metal alkoxides of formula (l _a ) as defined previously.

According to a preferred embodiment, the metal compound(s) are chosen from the metal alkoxides of formula (l _a ), in which: - M represents an atom chosen from transition metals such as titanium or zirconium, metals of the lanthanide family, post-transition metals such as aluminium or tin, metalloids such as boron, or alkaline-earth metals such as magnesium or calcium; - n represents the valency of the atom represented by M; - R ₁ represents a linear or branched saturated hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 1 to 6 carbon atoms. According to a more preferred embodiment, the metal compound(s) are chosen from the metal alkoxides of formula (I _a ) in which: - M represents an atom chosen from transition metals such as zirconium or titanium, metals of the lanthanide family, post-transition metals such as aluminium or tin, metalloids such as boron, and alkaline-earth metals such as magnesium; preferably, M represents a titanium or zirconium atom; - n represents the valency of the atom represented by M, notably 1, 2, 3 or 4, in particular 4; - R ₁ represents a methyl, ethyl, 2-ethylhexyl, propyl, isopropyl, n-butyl, isobutyl or t-butyl group. According to an even more preferred embodiment, the metal compound(s) are chosen from zirconium ethoxide (Zr(OC ₂ H ₅ ) ₄ ), zirconium propoxide (Zr(OCH ₂ CH ₂ CH ₃ ) ₄ ), zirconium isopropoxide (Zr(OCH(CH ₃ ) ₂ ) ₄ ), zirconium butoxide Zr(OCH ₂ CH ₂ CH ₂ CH ₃ ) ₄ , zirconium tert- butoxide (Zr(OC(CH3)3)4), titanium ethoxide (Ti(OC2H5)4), titanium propoxide (Ti(OCH ₂ CH ₂ CH ₃ ) ₄ ), titanium isopropoxide (Ti(OCH(CH ₃ ) ₂ ) ₄ ), titanium butoxide (Ti(OCH ₂ CH ₂ CH ₂ CH ₃ ) ₄ ), titanium tert-butoxide (Ti(OC(CH ₃ ) ₃ ) ₄ ), titanium 2-ethylhexyloxide (Ti(OCH ₂ CH(C ₂ H ₅ )(CH ₂ ) ₃ CH ₃ ) ₄ ), and mixtures thereof. Particularly preferably, the metal compound(s) are chosen from zirconium propoxide (Zr(OCH ₂ CH ₂ CH ₃ ) ₄ ), titanium propoxide (Ti(OCH ₂ CH ₂ CH ₃ ) ₄ ), titanium butoxide (Ti(OCH ₂ CH ₂ CH ₂ CH ₃ ) ₄ ) and mixtures thereof. Variants of the process according to the present invention “One-action” application method According to a first variant, the process involves applying to the keratin fibres a composition (A0) comprising: - an aqueous dispersion (D) as defined previously; and - one or more crosslinking agents as defined previously; and - one or more colouring agents as defined previously; and - one or more metal compounds as defined previously.

“Two-action” application method

According to a second variant, the process involves steps 1) and 2) below:

1) applying to the keratin fibres a dye composition (A1) comprising:

- an aqueous dispersion (D) as defined previously; and

- optionally one or more colouring agents as defined previously; and

- optionally one or more metal compounds as defined previously;

2) applying to the keratin fibres a composition (B1) comprising:

- one or more crosslinking agents as defined previously;

- optionally one or more colouring agents as defined previously; and

- optionally one or more metal compounds as defined previously; it being understood that:

- steps 1) and 2) are performed in the order 1) then 2) or 2) then 1), preferably in the order 1) then 2); and

- at least one of the compositions (A1) or (B1), preferably composition (A1), comprises one or more colouring agents as defined previously; and

- at least one of the compositions (A1) or (B1), preferably composition (A1), comprises one or more metal compounds as defined previously.

“Three-action” application method

According to a third variant, the process comprises steps T) to 3’) below:

T) applying to the keratin fibres a composition (C) comprising:

- one or more metal compounds as defined previously; and

- optionally one or more colouring agents as defined previously; and

2’) applying to the keratin fibres a composition (A2) comprising:

- an aqueous dispersion (D) as defined previously; and

- optionally one or more colouring agents as defined previously; and

3’) applying to the keratin fibres a composition (B2) comprising:

- one or more crosslinking agents as defined previously;

- optionally one or more colouring agents as defined previously; it being understood that:

- steps T) to 3’) are performed in the order T) then 2’) then 3’) or 2’) then 3’) then T), preferably in the order T) then 2’) then 3’); - at least one of the compositions (A2), (B2) or (C), preferably at least one of the compositions (A2) or (C), more preferentially the composition (A2) comprises one or more colouring agents as defined previously.

Additional features of the process

Composition (A) or (AO) or (A1) or (A2) preferably comprises less than 10% by weight of crosslinking agent(s) as defined previously, more preferentially less than 5% by weight of crosslinking agent(s) as defined previously, even more preferentially less than 2% by weight of crosslinking agent(s) as defined previously relative to the total weight of composition (A) or (A0) or (A1) or (A2) respectively, and better still composition (A) or (A0) or (A1) or (A2) is free of crosslinking agent(s) as defined previously.

Composition (B1) or (B2) preferably comprises less than 10% by weight, more preferentially less than 5% by weight, even more preferentially less than 2% by weight of (co)polymer(s) having at least one acetoacetate unit of formula (I) as defined previously relative to the total weight of the composition (B1) or (B2) respectively, and better still composition (B1) or (B2) is free of (co)polymer(s) having at least one acetoacetate unit of formula (I) as defined previously.

The total content of colouring agent(s) preferably ranges from 0.1% to 20% by weight, more preferentially from 2% to 10% by weight, even more preferentially from 4% to 8% by weight relative to the total weight of the composition(s) comprising same.

The total content of crosslinking agent(s) preferably ranges from 1 % to 50% by weight, more preferentially from 2% to 30% by weight, even more preferentially from 4% to 15% by weight relative to the total weight of the composition(s) comprising same.

The total content of metal compound(s) preferably ranges from 0.1% to 20% by weight, more preferentially from 0.5% to 15% by weight, even more preferentially from 1% to 10% by weight relative to the total weight of the composition(s) comprising same.

Compositions (A), (A0), (A1), (A2), (B1), (B2) and (C) are cosmetic compositions, i.e. they comprise only cosmetically acceptable ingredients. Compositions (A), (AO), (A1), (A2), (B1), (B2) and/or (C) according to the invention may also comprise a cosmetic additive chosen from fragrances, preserving agents, fillers, UV- screening agents, waxes, surfactants, moisturizers, vitamins, ceramides, antioxidants, free- radical scavengers and thickeners.

Compositions (A), (A0), (A1), (A2), (B1), (B2) and/or (C) according to the invention may be in any presentation form conventionally used for hair application. In a non-limiting manner, compositions (A), (A0), (A1), (A2), (B1), (B2) and/or (C) may be in the form of a lotion, a cream, a foam, a gel, a spray or a lacquer.

According to one particular embodiment, compositions (A), (A0), (A1) and/or (A2) further comprise one or more organic solvents chosen from C2-C4 alcohols, polyols, polyol ethers and mixtures thereof, preferably chosen from ethanol, isopropanol, glycerol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, dipropylene glycol, diethylene glycol, 2-butoxyethanol, propylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether and mixtures thereof, more preferentially ethanol.

According to one particular embodiment, compositions (B1 ), (B2) and/or (C) comprise water and/or one or more organic solvents chosen from C2-C4 alcohols, polyols, polyol ethers and mixtures thereof, preferably chosen from ethanol, isopropanol, glycerol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, dipropylene glycol, diethylene glycol, 2-butoxyethanol, propylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, and mixtures thereof, more preferentially ethanol.

According to one particular embodiment, compositions (A), (A0), (A1), (A2), (B1), (B2) and/or (C) further comprise one or more oils.

Preferably, the oil(s) are chosen from hydrocarbon-based oils.

The term “oil” means a water-immiscible non-aqueous compound that is liquid at room temperature (20°C) and at atmospheric pressure (760 mmHg).

The term “hydrocarbon-based oil” means an oil formed essentially from, or even consisting of, carbon and hydrogen atoms, and possibly oxygen and nitrogen atoms, and not containing any silicon or fluorine atoms. It may contain alcohol, ester, ether, carboxylic acid, amine and/or amide groups. The hydrocarbon-based oils may be chosen from: - C ₈ -C ₁₄ hydrocarbon-based oils, and notably: branched C ₈ -C ₁₄ alkanes, such as C ₈ -C ₁₄ isoalkanes of petroleum origin (also known as isoparaffins), such as isododecane (also known as 2,2,4,4,6-pentamethylheptane), isodecane and, for example, the oils sold under the Isopar or Permethyl trade names, linear alkanes, for instance n-dodecane (C ₁₂ ) and n-tetradecane (C ₁₄ ) sold by Sasol under the respective references Parafol 12-97 and Parafol 14-97, and also mixtures thereof, the undecane-tridecane mixture, the mixtures of n-undecane (C ₁₁ ) and of n-tridecane (C ₁₃ ) obtained in Examples 1 and 2 of patent application WO 2008/155059 from the company Cognis, and mixtures thereof, and short-chain esters (containing from 3 to 8 carbon atoms in total) such as ethyl acetate, methyl acetate, propyl acetate and n-butyl acetate; - hydrocarbon-based oils of plant origin such as triglycerides constituted of fatty acid esters of glycerol, the fatty acids of which may have chain lengths ranging from C ₄ to C ₂₄ , these chains possibly being linear or branched, and saturated or unsaturated; these oils are notably heptanoic acid or octanoic acid triglycerides, or alternatively wheatgerm oil, sunflower oil, grapeseed oil, sesame oil, corn oil, apricot oil, castor oil, shea oil, avocado oil, olive oil, soybean oil, sweet almond oil, palm oil, rapeseed oil, cottonseed oil, hazelnut oil, macadamia oil, jojoba oil, alfalfa oil, poppy oil, pumpkin oil, marrow oil, blackcurrant oil, evening primrose oil, millet oil, barley oil, quinoa oil, rye oil, safflower oil, candlenut oil, passion flower oil or musk rose oil; shea butter; or else caprylic/capric acid triglycerides, for instance those sold by the company Stéarinerie Dubois, - synthetic ethers containing from 10 to 40 carbon atoms, - linear or branched hydrocarbons of mineral or synthetic origin, in particular petroleum jelly, polydecenes, hydrogenated polyisobutene, in particular Parleam ^® , squalane and liquid paraffins, and mixtures thereof, - synthetic esters such as oils of formula R ₁ COOR ₂ in which R ₁ represents a linear or branched fatty acid residue including from 1 to 40 carbon atoms and R ₂ represents a, notably branched, hydrocarbon-based chain containing from 1 to 40 carbon atoms, on condition that the sum of the number of carbon atoms in R ₁ and R ₂ is greater than or equal to 10, for instance purcellin oil (cetostearyl octanoate), isopropyl myristate, isopropyl palmitate, C ₁₂ to C ₁₅ alkyl benzoates, hexyl laurate, diisopropyl adipate, isononyl isononanoate, 2-ethylhexyl palmitate, isostearyl isostearate, 2-hexyldecyl laurate, 2- octyldecyl palmitate, 2-octyldodecyl myristate, alcohol or polyalcohol heptanoates, octanoates, decanoates or ricinoleates such as propylene glycol dioctanoate; hydroxylated esters such as isostearyl lactate, diisostearyl malate and 2-octyldodecyl lactate; polyol esters and pentaerythritol esters;

- fatty alcohols that are liquid at room temperature, with a branched and/or unsaturated carbon-based chain containing from 12 to 26 carbon atoms, for instance octyldodecanol, isostearyl alcohol, oleyl alcohol, 2-hexyldecanol, 2-butyloctanol and 2- undecylpentadecanol;

- and mixtures thereof.

Preferably, the hydrocarbon-based oils are apolar, i.e. formed solely from carbon and hydrogen atoms.

According to a preferred embodiment, the oil(s) are chosen from Cs-Ci4 hydrocarbon-based oils.

According to a particularly preferred embodiment, the oil is isododecane.

According to a particular embodiment, the oil(s) are an isododecane/octyldodecanol mixture or an isododecane/isononyl isononanoate mixture.

Compositions (A), (AO), (A1), (A2), (B1), (B2) and/or (C) may also comprise one or more oils other than the oils described previously. In particular, it may be an oil chosen from:

- linear or branched hydrocarbons, in particular polydecenes, or hydrogenated polyisobutene, in particular Parleam;

- fatty alcohols containing from 12 to 26 carbon atoms, for instance octyldodecanol, 2- butyloctanol, 2-hexyldecanol, 2-undecylpentadecanol or oleyl alcohol;

- fluoro oils which are partially hydrocarbon-based and/or silicone-based;

- silicone oils such as polymethylsiloxanes (PDMS) which are non-volatile, linear or cyclic, liquid or pasty at room temperature, such as cyclomethicones, dimethicones, optionally including a phenyl group, such as phenyl trimethicones, phenyltrimethyl- siloxydiphenylsiloxanes, diphenylmethyldimethyltrisiloxanes, diphenyl dimethicones, phenyl dimethicones, polymethylphenylsiloxanes;

- and mixtures thereof.

The term “silicone oil” means an oil comprising at least one silicon atom and notably at least one Si-0 group.

The term “fluoro oil” means an oil comprising at least one fluorine atom. The pH of compositions (A), (AO), (A1), (A2), (B1 ), (B2) and (C) may be adjusted to the desired value by means of acidifying or alkaline agents or buffer systems, preferably by at least one acidifying agent.

Among the acidifying agents, examples that may be mentioned include mineral or organic acids, for instance hydrochloric acid, orthophosphoric acid, sulfuric acid, carboxylic acids, for instance acetic acid, tartaric acid, citric acid or lactic acid, and sulfonic acids.

Preferably, the acidifying agent is a mineral acid, preferably hydrochloric acid or lactic acid.

Compositions (A), (AO), (A1), (A2), (B1), (B2) and (C) may be used on wet or dry keratin fibres, and also on any type of fair or dark, natural or dyed, permanent-waved, bleached or relaxed fibres.

The application to the fibres may be performed via any standard means, in particular using a comb, a fine brush, a coarse brush or with the fingers.

After the application of one or more of the compositions (A), (AO), (A1), (A2), (B1 ), (B2) and (C), the fibres may be left to dry or may be dried, for example at a temperature of greater than or equal to 30°C. According to a particular embodiment, this temperature is greater than or equal to 40°C. According to a particular embodiment, this temperature is greater than or equal to 40°C and less than 120°C.

Preferably, if the fibres are dried, they are dried, in addition to a supply of heat, with a flow of air.

During drying, a mechanical action may be exerted on the locks, such as combing, brushing or running the fingers through. This operation may similarly be performed once the fibres have dried, naturally or otherwise.

The drying step(s) of the process of the invention may be performed with a drying device such as a hood, a hairdryer, a straightening iron or a Climazon.

When the drying step(s) are performed with a hood or a hairdryer, the drying temperature may range from 40°C to 110°C and preferably from 50°C to 90°C.

The process may also comprise, after the application of one or more of the compositions (A), (AO), (A1), (A2), (B1), (B2) and (C), a step of heat treatment of the keratin fibres using a heating means at a temperature of at least 120°C.

Preferably, the heat treatment step is performed at a temperature ranging from 120°C to 230°C, more preferentially from 150°C to 210°C, even more preferentially from 160°C to 210°C, better still from 180°C to 210°C. Advantageously, the heating means is chosen from a straightening iron, a crimping or curling iron, a steam iron and a heating comb, preferably a straightening iron, a crimping or curling iron or a steam iron, more preferentially a straightening iron.

Advantageously, the heating means is a straightening iron, a crimping or curling iron or a steam iron. According to this embodiment, the heating means is applied to dry hair, i.e. hair that has been dried beforehand using air or by means of a device such as a hairdryer or a heating hood, the temperature of which is less than 120°C.

More preferentially, the heat treatment step using a heating means which is a straightening iron, a crimping or curling iron or a steam iron, preferably a straightening iron, is performed at a temperature ranging from 120° to 230°C, notably from 150°C to 210°C, even more preferentially from 160°C to 210°C, better still from 180°C to 210°C.

Preferably, the duration of heat treatment of the hair with a heating means which is a straightening iron, a crimping or curling iron or a steam iron, preferably a straightening iron, ranges from 100 milliseconds to 2 minutes, more preferentially from 500 milliseconds to 1 minute, even more preferentially from 1 second to 30 seconds, better still from 3 seconds to 20 seconds, or even from 4 seconds to 10 seconds. This heat treatment step can be repeated several times on each lock of hair.

The heating means which is a straightening iron, a crimping or curling iron or a steam iron, preferably a straightening iron, may be applied to the hair in successive strokes of a few seconds, or by gradually moving or gliding along the keratin fibres such as the hair.

Preferably, the application of the heating means which is a straightening iron, a crimping or curling iron or a steam iron, preferably a straightening iron, is done in a continuous movement from the roots to the ends of the hair, in one or more passes.

After these steps, a final rinse and/or shampoo wash may optionally be performed.

Particular composition

According to a second aspect, a subject of the present invention is a composition (A0) comprising:

- an aqueous dispersion (D) as defined previously; and

- one or more crosslinking agents as defined previously; and

- one or more colouring agents as defined previously; and

- one or more metal compounds as defined previously.

Multi-compartment kit or device According to a third aspect, a subject of the present invention is a kit or device containing several separate compartments, comprising:

■ in a first compartment: a composition (A1) comprising:

- an aqueous dispersion (D) as defined previously; and

- optionally one or more colouring agents as defined previously; and

- optionally one or more metal compounds as defined previously; and

■ in a second compartment separate from the first: composition (B1) comprising:

- one or more crosslinking agents as defined previously; and

- optionally one or more colouring agents as defined previously; and

- optionally one or more metal compounds as defined previously; it being understood that:

- at least one of the compositions (A1) or (B1), preferably composition (A1), comprises one or more colouring agents as defined previously; and

- at least one of the compositions (A1) or (B1), preferably composition (B1) comprises one or more metal compounds as defined previously; or

■ in a first compartment: a composition (A2) comprising:

- an aqueous dispersion (D) as defined previously; and

- optionally one or more colouring agents as defined previously; and

■ in a second compartment separate from the first: a composition (B2) comprising:

- one or more crosslinking agents as defined previously; and

- optionally one or more colouring agents as defined previously; and

■ in a third compartment separate from the first and the second: a composition (C) comprising:

- one or more metal compounds as defined previously; and

- optionally one or more colouring agents as defined previously; it being understood that:

- at least one of the compositions (A2), (B2) or (C), preferably at least one of the compositions (A2) or (C), more preferentially the composition (A2) comprises one or more colouring agents as defined previously.

Examples

The examples that follow allow the invention to be understood more clearly, without, however, being limiting in nature. In the examples which follow, unless otherwise indicated, all the amounts are shown as mass percentages relative to the total weight of the composition.

Example A: Preparation of an aqueous dispersion 1 in accordance with the invention based on the polyvinylpyrrolidone/methyl acrylate/acetoacetoxyethyl methacrylate (2/88/10) system

In a 1 litre pilot reactor, the feedstock is composed of 5 g of poly-1-vinyl-2-pyrrolidinone, 150 g of ethanol, 350 g of water and 1.2 g of KPS initiator. The medium is degassed with argon and then heated to 80°C with stirring (150 rμm).

Once the feedstock has reached a temperature of 80°C, a mixture of 25 g of acetoacetoxyethyl methacrylate and 220 g of methyl acrylate is introduced by running in over 1 hour with a pilot pump.

The reaction is continued for 7 hours at 80°C and then allowed to cool to room temperature. The reaction medium is then stripped by complete distillation of the ethanol to recover the aqueous dispersion having a solids content of 39.5% by weight relative to the total weight of the aqueous dispersion.

The polymer in aqueous dispersion is characterized by gel permeation chromatography (GPC). The results are detailed in the table below.

Example B: Preparation of an aqueous dispersion 2 in accordance with the invention based on the polvvinylpyrrolidone/isobornyl acrylate/2-ethylhexyl acrylate/acetoacetoxyethyl methacrylate (2/59/29/10) system

In a 1 litre pilot reactor, the feedstock is composed of 5 g of poly-1-vinyl-2-pyrrolidinone, 150 g of ethanol, 350 g of water and 1.2 g of KPS initiator. The medium is degassed with argon and then heated to 80°C with stirring (150 rμm).

Once the feedstock has reached a temperature of 80°C, a mixture of 25 g of acetoacetoxyethyl methacrylate, 147.5 g of isobornyl acrylate and 72.5 g of 2-ethylhexyl acrylate is introduced by running in over 1 hour with a pilot pump.

The polymerization is continued for 7 hours at 80°C and then allowed to cool to room temperature. The reaction medium is then stripped by complete distillation of the ethanol.

Finally, the polymer is in the form of an aqueous dispersion with a solids content of 43% by weight relative to the total weight of the aqueous dispersion.

The polymer in aqueous dispersion is characterized by GPC. The results are detailed in the table below.

Example C: Preparation of an aqueous dispersion 3 in accordance with the invention based on the polyvinylpyrrolidone/butyl methacrylate/PDMS 12K methacrylate/acetoacetoxyethyl methacrylate (2/83/5/10) system

In a 1 litre pilot reactor, the feedstock is composed of 5 g of poly-1-vinyl-2-pyrrolidinone, 150 g of ethanol, 350 g of water and 1.2 g of KPS initiator. The medium is degassed with argon and then heated to 80°C with stirring (150 rμm).

Once the feedstock has reached a temperature of 80°C (nominal temperature of the reaction medium), a mixture of 25 g of acetoacetoxyethyl methacrylate, 207.5 g of butyl methacrylate and 12.5 g of PDMS 12K methacrylate is introduced by running in over 1 hour with a pilot pump.

The polymerization is continued for 7 hours at 80°C and then allowed to cool to room temperature. The reaction medium is then stripped by complete distillation of the ethanol. Finally, the polymer is in the form of an aqueous dispersion with a solids content of 39% by weight relative to the total weight of the aqueous dispersion.

Example D: Preparation of an aqueous dispersion 4 in accordance with the invention based on the polyvinylpyrrolidone/methyl acrylate/stearyl methacrylate/acetoacetoxyethyl methacrylate (2/68/20/10) system

In a 1 litre pilot reactor, the feedstock is composed of 5 g of poly-1-vinyl-2-pyrrolidinone, 150 g of ethanol, 350 g of water and 1.2 g of KPS initiator. The medium is degassed with argon and then heated to 80°C with stirring (150 rμm).

Once the feedstock has reached a temperature of 80°C (nominal temperature of the reaction medium), a mixture of 25 g of acetoacetoxyethyl methacrylate, 170 g of methyl acrylate and 50 g of stearyl methacrylate is introduced by running in over 1 hour with a pilot pump.

The polymerization is continued for 7 hours at 80°C and then allowed to cool to room temperature. The reaction medium is then stripped by complete distillation of the ethanol.

Finally, the polymer is in the form of an aqueous dispersion with a solids content of 44% by weight relative to the total weight of the aqueous dispersion.

The polymer in aqueous dispersion is characterized by GPC. The results are detailed in the table below. Example E: Preparation of an aqueous dispersion 5 according to the invention based on the polyvinylpyrolidone/acetoacetoxyethyl methacrylate system (10/90)

In a 1 litre pilot reactor, the feedstock is composed of 25 g of poly-1-vinyl-2-pyrrolidinone, 150 g of ethanol, 350 g of water and 1.2 g of KPS initiator. The medium is degassed with argon and then heated to 80°C with stirring (150 rμm).

Once the feedstock has reached a temperature of 80 °C (reaction medium nominal temperature), a mixture of 225 g of acetoacetoxyethyl methacrylate is introduced by running in over 1 hour with a pilot pump.

The polymerization is continued for 7 hours at 80 °C and then allowed to cool to room temperature. The reaction medium is then stripped by distilling off all the ethanol.

Finally, the polymer is in the form of an aqueous dispersion containing 44% by weight of dry extract relative to the total weight of the aqueous dispersion.

Examples 1 to 10

Compositions tested

The following compositions were prepared and then used in the following examples. The amounts are given in g per 100 g of composition.

Compositions (A1)

[Table 1]

Compositions (B1), (B2) and (B3)

[Table 2]

Compositions (C1), (C2) and (C3)

[Table 3] Application protocol

The application protocol used in the following examples involves applying either two different compositions or three different compositions.

Application protocol No. 1 (with two different compositions) The application protocol with two different compositions involves the following steps: - applying to a lock of dry hair composition (Ax) in a bath ratio of 0.5 g of composition (Ax)/g of hair; and then

- drying the lock with a hairdryer; and then

- applying to the lock composition (Bx) in a bath ratio of 0.5 g of composition (Bx)/g of hair; and then

- drying the lock with a hairdryer.

Application protocol No. 2 (with three different compositions)

The application protocol with three different compositions involves the following steps:

- applying to a lock of dry hair composition (Cx) in a bath ratio of 0.5 g of composition (Cx)/g of hair; and then

- applying to the lock composition (Ax) in a bath ratio of 0.5 g of composition (Ax)/g of hair; and then

- drying the lock with a hairdryer; and then

- applying to the lock composition (Bx) in a bath ratio of 0.5 g of composition (Bx)/g of hair; and then

- drying the lock with a hairdryer.

Shampooing protocol

The shampoo-washing resistance evaluations were conducted according to the following shampoo washing protocol, 24 hours after applying the compositions according to the application protocol described previously:

The locks of dyed hair are combed, moistened with water at 35°C and then passed between the fingers five times for 5 seconds. The locks of hair are then squeezed dry between two fingers.

A standard shampoo (Garnier Ultra Doux) is applied uniformly to the dyed locks in a proportion of 0.4 g of standard shampoo per gram of locks, the locks of hair being massaged gently along their length (six passes) for 15 seconds, from the root to the end.

The locks of hair are then placed on a watch glass and left to stand for 1 minute.

Next, the locks of hair are rinsed with water while passing the locks between the fingers (15 passes). The locks of hair are then squeezed dry between two fingers before the next shampoo wash.

Once the tests of several shampoo washes have been performed, the locks of hair are combed and dried with a hairdryer. Evaluation of the persistence of the colour with respect to shampoo washing

The persistence of the colour of the locks was evaluated in the CIE L* a* b* system, using a Minolta CM-3610d spectrophotometer.

In this L*a*b* system, L* represents the intensity of the colour, a* indicates the shade of the colour on the green/red colour axis and b* indicates the shade of the colour on the blue/yellow colour axis. The lower the value of L*, the darker or more intense the colour. The higher the value of a*, the redder the shade, and the higher the value of b*, the yellower the shade.

The persistence of the colouring is evaluated by the colour difference AEp _erS jstence between the dyed locks before shampooing, then after having undergone eight shampoo washes according to the protocol described above. The lower the AEp _erS jstence value, the more persistent the colour with respect to shampoo washing.

The AEpersistence value is calculated according to the following equation:

In this equation, L*, a* and b* represent the values measured after dyeing the hair and after performing shampoo washes, and Lo*, ao* and bo* represent the values measured after dyeing the hair but before shampoo washing.

Examples 1 to 4 (locks of natural hair containing 90% white hair strands (90% NW))

The compositions and protocol used in each of the Examples 1 to 4 and the measured colour persistence values are summarized in the table below. The locks of hair used in Examples 1 to 3 are locks of natural hair containing 90% white hair strands (also known as 90% NW).

Colorimetric measurements:

[Table 4] The dyeing process according to the invention makes it possible to obtain good persistence of the colouring on natural hair. Furthermore, the hair treated by means of the process according to the invention shows good strand separation after treatment and after 8 shampoo washes and has a pleasant feel.

Examples 5 to 7 (sensitized hair locks with an alkaline solubility of 20 (AS20))

The compositions and protocol used in each of the Examples 5 to 7 and the measured colour persistence values are summarized in the table below. The locks of hair used are sensitized hair locks with an alkaline solubility of 20 (AS20).

Colorimetric measurements:

[Table 5]

The dyeing process according to the invention makes it possible to obtain good persistence of the colouring on sensitized hair with an alkaline solubility of 20 (AS 20).

Examples 8 to 10: Measurement of the dyeing selectivity

The dyeing selectivity is the variation of the colour between natural hair and permanent- waved hair. The natural hair is representative of the nature of the hair at the root, whereas the permanent-waved hair is representative of the nature of the hair at the end.

The selectivity is evaluated in the CIE L* a* b* system, using a Minolta CM-3610d spectrophotometer.

In this L*a*b* system, L* represents the intensity of the colour, a* indicates the shade of the colour on the green/red colour axis and b* indicates the shade of the colour on the blue/yellow colour axis.

AEseiectivity, which is the variation in colour between the natural hair and the permanent- waved hair, is obtained by means of the following equation:

In this equation, L*, a* and b* represent the values measured after dyeing the natural hair, and Lo*, ao* and bo* represent the values measured after dyeing the permanent-waved hair. The lower the value of AE _se iectivity, the lower the selectivity and the more uniform the colouring along the hair strands.

The compositions and protocol used in each of the Examples 8 to 10 and the measured colour selectivity values are summarized in the table below. The locks of hair used are locks of natural hair containing 90% white hair strands (also known as 90% NW) and locks of sensitized permanent-waved containing 90% white hair strands.

Selectivity measurement:

[Table 6] The colouring obtained via the process according to the present invention is sparingly selective.