Keratin material treatment process using at least one polyester compound bearing acetoacetate functions

Abstract

The present invention relates to a process for treating keratin materials, comprising the application to said keratin materials, in one or more successive steps, of at least: i) at least one polyester of formula (I) below, comprising at least two acetoacetate functions (including the optical or geometrical isomers and / or solvates thereof such as hydrates) or a composition containing same: (Z)–[O-C(O)-C(Ra)(Rb)-C(O)-R4]u (I), in which formula (I) Z, u, R4, Ra and Rb are as defined in the description, and optionally ii) at least one crosslinking agent

Description

[0001] 1 Keratin material treatment process using at least one polyester compound bearing acetoacetate functions Technical field 5 The present invention relates more particularly to the cosmetic field of keratin materials, and notably to that of caring for and / or making up the skin and / or the lips and / or the eyelashes and / or the eyebrows, and that of caring for, styling and / or dyeing keratin fibers and preferably the hair. The aim is thus notably to propose novel treatment processes, notably cosmetic treatment 10 processes, comprising the application to keratin materials of a polyester compound bearing acetoacetate functions, and optionally a crosslinking agent, which are most particularly advantageous in terms of their technical performance, notably in terms of the resistance of the deposits and the gloss qualities they afford. 15 Prior art Cosmetic products conventionally require the use of one or more film-forming polymers in order to obtain a quality deposit of these products on keratin materials, and in particular to satisfy the expectations detailed below. Thus, in the field of skin and / or lip makeup, it is most particularly expected that the deposit 20 formed does not transfer on contact with the fingers or clothing. It must also have good persistence of the gloss, and good resistance to contact with water, notably rain or during showering or even perspiration, and also resistance to sebum, or even to contact with edible fats, notably edible oils when this deposit is formed on the lips. Moreover, this deposit must be comfortable. 25 For this purpose, dispersions of polymer particles of nanometric size are used as film- forming agent in makeup products such as mascaras, eyeliners, eyeshadows or lipsticks, and in products for haircare application, and more particularly in their organic and notably oily phases. However, the persistence over time of prior art compositions, in particular as regards the 30 hairstyle, is not always satisfactory. As regards the gloss, this is generally obtained by formulating glossy oils, such as polybutenes, which are characterized by their apolar nature. However, this type of oil has 2 little ability to disperse pigments. Similarly, cosmetic compositions comprising one or more glossy oils may have a color persistence over time that is not totally satisfactory from a cosmetic point of view, such as a persistence of less than 4 hours, or even less than one hour. These oils also have the drawback of being tacky, and of affording a gloss that persists poorly 5 over time, for example, less than 1 or 2 hours. Finally, compositions incorporating these oils may migrate into the fine lines and wrinkles, and thus be capable of generating an unesthetic effect detrimental to their use by consumers. In addition, the formulation of environmentally friendly cosmetic products, i.e. products whose design and development take account of environmental issues, is becoming a major 10 preoccupation for contributing toward tackling global challenges. It is thus essential to propose more sustainable compositions and / or preparation processes and / or ingredients, thus enabling these environmental challenges to be met. Alkyd resins afford advantageous properties in cosmetic applications. Furthermore, these resins may be totally or partially biobased, and some of them are biodegradable. However, 15 these alkyd resins have a major drawback in that they are sensitive to conventional cosmetic aggressors such as fats, like olive oil or sebum, and / or to water, or even are sensitive to fragmentation, which limits their interest for application on keratin materials. The use of polycondensates, also referred to hereinbelow as polyesters, as an alternative to or in addition to glossy oils, as described for example in patent application EP 1870082, 20 has made it possible to partially overcome the abovementioned shortcomings, notably by making it possible to obtain compositions with, on the one hand, improved gloss, reflected by a greater shine and a wet look, and, on the other hand, good persistence of this gloss over time, notably after a few hours, and notably beyond 4 hours. However, it would be desirable to be able to reinforce the efficacy of these compositions in terms of color persistence, in 25 particular over time and notably after a meal, and in terms of gloss persistence over time. Moreover, there is strong consumer demand for the use of more natural compositions, using compounds of natural origin, possibly that are modified. In this context, it is important to develop processes for preparing cosmetic products and / or cosmetic ingredients with an improved carbon footprint, that are capable of reducing the 30 generation of carbon dioxide throughout the life of the product and / or that are inexpensive in terms of energy and water and / or use greener solvents and / or have fewer synthetic steps and / or are economical in terms of atoms. 3 Moreover, in the field of haircare, a new range of products known as “Hair Makeup” has recently been developed. These products guarantee temporary hair dyeing that lasts after 1 to 3 shampoo washes. They are thus a particularly attractive alternative for consumers to permanent hair dyeing, 5 provided, of course, that the coloring effect is effectively guaranteed to last after contact with water and a few shampoo washes. This requirement is also notably satisfied by the use of effective film-forming agents. Thus, WO 2003 / 089494 and WO 2003 / 087192 propose acetoacetate-functionalized alkyd resins that are capable of undergoing crosslinking as a film-forming agent, and which may 10 be used to prepare industrial coatings containing low levels of VOCs. In general, the treatments and processes described above do not make it possible to obtain deposits, either on keratin fibers or on the skin and lips, which satisfy all the abovementioned requirements, namely very good water resistance, in particular to shampoo washing for the hair, and / or resistance to greasy substances notably for the lips, which are moreover 15 comfortable to wear for the users, which have high gloss that is stable over time, and which, in the case of haircare use, provide very satisfactory styling hold or color persistence, while at the same time meeting the need for naturalness, biobased nature and / or biodegradability expressed by certain consumers and / or formulations in which the presence of a fatty phase is not desired. 20 Disclosure of the invention There is thus still a need for a treatment process, notably a cosmetic treatment process, intended for application to the skin, which makes it possible to obtain a deposit that is non- tacky, transfers little, if at all, is glossy, comfortable, long-lasting and the use of which does 25 not necessarily require the presence of a fatty phase, while at the same time being of natural origin. There is also still a need for a treatment process, notably a cosmetic treatment process, which allows deposits to be obtained that are resistant to water and fatty substances, in particular sebum. 30 There is also still a need for a treatment process, notably a cosmetic treatment process, which affords deposits that have high gloss qualities. 4 There is also a need for a treatment process, notably a coloring cosmetic treatment process, which is intended for application to the hair and which affords deposits that have good resistance to water and shampoo washing in order to ensure a color persistence over time that is comparable to direct dyeing. 5 There is also a need for a treatment process, notably a cosmetic and notably non-coloring treatment process, which is intended for application to the hair and which affords water- resistant styling properties, notably curl hold. The present invention is specifically directed toward meeting all or some of these needs. 10 Summary of the invention These problems are solved by performing a process for treating keratin materials, comprising the application to said keratin materials, in one or more successive steps, of at least: i) at least one polyester of formula (I) below, comprising at least two acetoacetate functions, and also the optical or geometrical isomers thereof, and / or solvates thereof, such as hydrates, 15 or a composition containing same: (Z)–[O-C(O)-C(Ra)(Rb)-C(O)-R4]u (I) in which formula (I): - Z denotes a multivalent radical derived: from an alkyd resin (A) obtained by reaction of: 20 - from 10% to 62% by mass of at least one polyol; - from 10% to 62% by mass of at least one polyacid; - from 35% to 60% by mass of at least one fatty alcohol and / or at least one fatty monoacid; and - from 0% to 20% by mass of at least one monocarboxylic acid; 25 the mass percentages being expressed relative to the total weight of the alkyd resin (A); or an alkyd resin (B) obtained by reacting an ethylenically unsaturated alkyd resin (A) with at least one (poly)hydroxy thiol; - u is an integer greater than 2; 30 - R4represents a linear or branched, saturated or unsaturated C1-C6monovalent hydrocarbon- based radical, preferably a (C1-C4)alkyl group, in particular methyl or tert-butyl, more preferentially methyl; 5 - Raand Rb, which may be identical or different, represent a hydrogen atom or a (C1-C4)alkyl group, preferably a hydrogen atom; and ii) optionally at least one crosslinking agent. According to a preferred embodiment, the treatment process according to the invention 5 comprises the application of at least ii) a crosslinking agent. According to a preferred embodiment, the treatment process according to the invention also comprises the application of at least iv) a cosmetic active agent, to said keratin materials. According to a preferred embodiment, the process according to the invention comprises the application i) of at least one polyester of formula (I), the optical or geometrical isomers 10 thereof, the acid or base salts thereof, and / or the solvates thereof, such as hydrates, or of a composition containing same, optionally the application ii) of at least one crosslinking agent, and the application iv) of at least one cosmetic active agent, to said keratin materials. According to one embodiment, the process comprises the application of i), optionally ii) and optionally iv) to damp or wet keratin materials. 15 The inventors thus found, surprisingly, that the application to keratin materials of the ingredients i), and optionally ii) and iv), makes it possible to obtain deposits on the skin which have good resistance to external attacking factors, for instance water, oils, notably food oils, sweat and / or sebum, which have high gloss that is stable over time, and which are therefore endowed with very good staying power over time. Advantageously, the deposits 20 obtained via the processes according to the invention are also very comfortable. They are not tacky and do not transfer. Applying ingredients i), and possibly ii) and iv) to keratin materials also affords deposits on keratin fibers which show good resistance to shampoo washing and to water. Applying ingredients i), and possibly ii) and iv), to keratin materials also affords very glossy 25 and persistent deposits. 30 Definitions For the purposes of the present invention and unless otherwise indicated: 6 - The term “multivalent” refers to a radical which is at least divalent; the valency of the radical R1 is equal to n as defined previously, the radical R1 thus being “n-valent”. By way of example, when n is equal to 3, the radical R1 is trivalent; - For the purpose of the present invention, the term “keratin materials” is notably understood 5 to denote the lips, skin, nails and keratin fibers, in particular the eyelashes, eyebrows and hair, preferably the lips and / or the hair. - The term “cosmetic active agent” means an organic or organosilicon compound or a mineral compound which can be incorporated into a cosmetic composition to give an effect on keratin materials, whether this effect is immediate or provided by repeated applications. 10 As examples of cosmetic active agents, mention may be made of colored or uncolored, fluorescent or non-fluorescent compounds such as optical brighteners, or UVA and / or UVB screening agents, antiaging active agents or active agents intended for providing a benefit to the skin such as active agents having action on the barrier function, deodorant active agents, antiperspirant active agents, desquamating active agents, antioxidant active agents, 15 moisturizing active agents, sebum-regulating active agents, active agents intended for combating the effects of pollution, antimicrobial or bactericidal active agents, fragrances and dyestuffs such as direct dyes or pigments, preferably pigments. Preferentially, the cosmetic active agents are chosen from a) dyestuffs chosen from pigments, direct dyes, and mixtures thereof, b) active agents for caring for keratin materials, 20 preferably the skin, c) UV-screening agents, and d) mixtures thereof. - For the purposes of the present invention, the term “fatty substance” means an organic compound that is insoluble in water at ordinary temperature (25°C) and at atmospheric pressure (760 mmHg) (solubility of less than 5%, preferably less than 1% and even more preferentially less than 0.1%); in addition, the fatty substances are soluble in organic solvents 25 under the same temperature and pressure conditions, for instance in halogenated solvents such as chloroform or dichloromethane, lower alcohols such as ethanol or aromatic solvents such as benzene or toluene. - The term “alkyl” means a linear or branched, saturated hydrocarbon-based radical. - The term “(Cx-Cy)alkyl group” means an alkyl group comprising from x to y carbon atoms. 30 - The term “(hetero)aryl” means aryl or heteroaryl groups. - The term “(hetero)cycloalkyl” means cycloalkyl or heterocycloalkyl groups. 7 - The “aryl” or “heteroaryl” radicals or the aryl or heteroaryl part of a radical may be substituted with at least one substituent borne by a carbon atom, chosen from: - a C1-C6 and preferably C1-C4 (poly)(hydroxy)alkyl radical; - a halogen atom such as chlorine, fluorine or bromine; 5 - a hydroxyl group; - a C1-C2 alkoxy radical; a C2-C4 (poly)hydroxyalkoxy radical; - an amino radical; - an amino radical substituted with one or two identical or different C1-C6and preferably C1-C4 alkyl radicals; 10 - an acylamino radical (-N(R)-C(O)-R’) in which the radical R is a hydrogen atom; - a C1-C4alkyl radical and the radical R’ is a C1-C4alkyl radical; a carbamoyl radical ((R)2N-C(O)-) in which the radicals R, which may be identical or different, represent a hydrogen atom or a C1-C4 alkyl radical; - an alkylsulfonylamino radical (R’-S(O)2-N(R)-) in which the radical R represents a 15 hydrogen atom or a C1-C4alkyl radical and the radical R’ represents a C1-C4alkyl radical, or a phenyl radical; - an aminosulfonyl radical ((R)2N-S(O)2-) in which the radicals R, which may be identical or different, represent a hydrogen atom or a C1-C4alkyl radical; - a carboxylic radical in acid or salified (preferably with an alkali metal or a substituted 20 or unsubstituted ammonium) form; - a cyano group (CN); - a polyhalo(C1-C4)alkyl group, preferentially trifluoromethyl (CF3). - The cyclic or heterocyclic part of a non-aromatic radical may be substituted with at least one substituent borne by a carbon atom, chosen from the following groups: 25 - hydroxyl; - C1-C4 alkoxy, C2-C4 (poly)hydroxyalkoxy; - alkylcarbonylamino ((R-C(O)-N(R’)-), in which the radical R’ is a hydrogen atom or a C1-C4alkyl radical and the radical R is a C1-C2alkyl radical or an amino radical substituted with one or two identical or different C1-C4 alkyl groups; 30 - alkylcarbonyloxy ((R-C(O)-O-), in which the radical R is a C1-C4alkyl radical or an amino radical substituted with one or two identical or different C1-C4alkyl groups; 8 - alkoxycarbonyl ((R-O-C(O)-) in which the radical R is a C1-C4alkyl radical or an amino radical substituted with one or two identical or different C1-C4 alkyl groups; - A cyclic or heterocyclic radical, or a non-aromatic part of an aryl or heteroaryl radical, may also be substituted with one or more oxo groups. 5 - A hydrocarbon-based chain is unsaturated when it includes one or more double bonds and / or one or more triple bonds, which may or may not be conjugated. - An “aryl” radical represents a monocyclic or fused or non-fused polycyclic hydrocarbon- based group comprising from 6 to 14 carbon atoms, and at least one ring of which is aromatic; preferentially, the aryl radical is a phenyl, biphenyl, naphthyl, indenyl, anthracenyl 10 or tetrahydronaphthyl. - a “heteroaryl” radical represents a monocyclic or fused or non-fused polycyclic, 5- to 14- 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 radical is chosen from acridinyl, benzimidazolyl, benzobistriazolyl, benzopyrazolyl, 15 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, 20 thiazolopyridyl, thiazoylimidazolyl, thiopyrylyl, triazolyl and xanthylyl. - A “cyclic” or “cycloalkyl” radical is a monocyclic or fused or non-fused polycyclic, non- aromatic cyclic hydrocarbon-based radical containing from 5 to 14 carbon atoms, which may include one or more unsaturations; the cycloalkyl is preferably a cyclohexyl group. - A “heterocyclic” or “heterocycloalkyl” radical is a monocyclic or fused or non-fused 25 polycyclic 3- to 9-membered non-aromatic cyclic radical, including from 1 to 4 heteroatoms chosen from nitrogen, oxygen, sulfur and selenium atoms; preferably, the heterocycloalkyl is chosen from epoxide, piperazinyl, piperidyl, morpholinyl and dithiolane. - An “alkyl” radical is a linear or branched, in particular C1-C6and preferably C1-C4saturated hydrocarbon-based radical. 30 - An “alkoxy” radical is an alkyl-oxy radical for which the alkyl radical is a linear or branched C1-C6and preferentially C1-C4hydrocarbon-based radical. 9 - A “(poly)(hydroxy)alkyl” radical denotes a C1-C6and preferably C1-C4alkyl radical optionally substituted with one or more hydroxyl radicals, preferably substituted with from 1 to 4 hydroxyl groups, more particularly between 1 and 3. - The term “polyvalent radical” means a radical which is at least divalent, such as a divalent, 5 trivalent or tetravalent radical, preferably divalent or trivalent. - The term “anionic counterion” means an anion or an anionic group associated with the cationic charge; more particularly, the anionic counterion is chosen from: i) halides such as chloride or bromide; ii) nitrates; iii) sulfonates, including C1-C6alkylsulfonates: Alk- S(O)2O- such as methanesulfonate or mesylate and ethanesulfonate; iv) arylsulfonates: Ar- 10 S(O)2O- such as benzenesulfonate and toluenesulfonate or tosylate; v) citrate; vi) succinate; vii) tartrate; viii) lactate; ix) alkyl sulfates: Alk-O-S(O)O- such as methyl sulfate and ethyl sulfate; x) aryl sulfates: Ar-O-S(O)O- such as benzene sulfate and toluene sulfate; xi) alkoxy sulfates: Alk-O-S(O)2O- such as methoxy sulfate and ethoxy sulfate; xii) aryloxy sulfates: Ar-O-S(O)2O-; xiii) phosphate; xiv) acetate; xv) triflate; and xvi) borates such as 15 tetrafluoroborate, and mixtures thereof. - The “solvates” represent hydrates and also the combination with linear or branched C2-C6 alcohols, also known as (C2-C6)alkanols, such as ethanol, isopropanol or n-propanol. - The term “UV-A screening agent” means a chromophore derived from a compound which screens out (or absorbs) UV-A ultraviolet rays at a wavelength of between 320 and 400 nm. 20 A distinction may be made between short UV-A screening agents (which absorb rays at a wavelength of between 320 and 340 nm) and long UV-A screening agents (which absorb rays at a wavelength of between 340 and 400 nm). - The term “UV-B screening agent” means a chromophore derived from a compound which screens out (or absorbs) UV-B ultraviolet rays at a wavelength of between 280 and 320 nm. 25 - The term “chromophore” means a radical derived from a colorless or colored compound that is capable of absorbing UV and / or visible radiation at a wavelength λabs of between 250 and 800 nm. Preferably, the chromophore is colored, i.e. it absorbs wavelengths in the visible range, i.e. preferably between 400 and 800 nm. Preferably, the chromophores appear colored to the eye, particularly between 400 and 700 nm (Ullmann’s Encyclopedia, 2005, Wiley- 30 VcH, Verlag “Dyes, General Survey”, § 2.1 Basic Principle of Color). - The term “anhydrous composition” means that said composition contains an amount of less than 5% by weight of water, preferentially less than 3% by weight of water, better still less 10 than 1% by weight of water, relative to the total weight of the composition in question; even more preferentially, the composition under consideration is free of water. - The terms “coloring agent” and “dyestuff” are equivalent. Throughout the description, including the claims, the term “including a” should be 5 understood as being synonymous with “including at least one” or synonymous with “including one or more”, unless otherwise mentioned. - the term “polycondensate” means a polyester resulting from the functionalization of an alkyd resin with acetoacetate functions. - The term “(co)polymer” means a homopolymer or a copolymer. 10 - The term “homopolymer” means a polymer derived from the repetition of polymer or monomer units, said monomers of which are all identical, i.e. of the same chemical nature (for example -A-A-A-...-A-A-), - The term “copolymer” means a polymer derived from the repetition of polymer or monomer units, of which at least two repeating monomers are different, i.e. of different 15 chemical nature (for example -A-B-A-A-...-B-A-, it being understood that A is different from B); preferably, the (co)polymer(s) of the invention are copolymers. The expressions “between … and …”, “comprises from … to …”, “formed from … to …” and “ranging from … to …” should be understood as being inclusive of the limits, unless otherwise specified. 20 It is understood that the treatment processes according to the invention, and also the compositions used, are non-therapeutic. Detailed description 25 PROCESS FOR TREATING KERATIN MATERIALS The first subject of the invention is a treatment process in one or more steps comprising the application to keratin materials, notably keratin fibers or the skin, of at least: i) at least one polyester of formula (I), comprising at least two acetoacetate functions, and also the optical or geometrical isomers thereof, and / or solvates thereof, such as hydrates, or 30 a composition containing same; ii) optionally at least one crosslinking agent, in particular as defined below; 11 iv) optionally at least one cosmetic active agent, in particular as defined previously and hereinbelow; and v) optionally at least one fatty substance, in particular at least one oil, which is preferably volatile. 5 According to a particular embodiment of the invention, the treatment process according to the invention involves the simultaneous application of the ingredients i), optionally ii), optionally iv), and optionally v). According to another particular embodiment of the invention, the treatment process according to the invention comprises at least two sequential steps in which ingredients i) and 10 ii) are applied separately to the keratin materials, it being understood that each of the ingredients i) and ii) is optionally applied simultaneously with the ingredient(s) iv) when present and / or with the ingredient(s) v) when present. According to a particular embodiment, the ingredient(s) i) are applied to the keratin materials, then the ingredient(s) ii) are applied to the keratin materials, if present, it being 15 understood that the ingredient(s) iv), when present, may be applied together with i) and / or with ii) and / or with v), when v) is present, and that the ingredient(s) v), when present, may be applied together with i) and / or ii) and / or iv), preferably with i) and / or ii). According to another particular embodiment, the ingredient(s) ii) are applied to the keratin materials, and the ingredient(s) i) are then applied to the keratin materials, it being 20 understood that the ingredient(s) iv), when present, may be applied together with i) and / or ii), and that the ingredient(s) v), when present, may be applied with i) and / or with ii) and / or with iv), when iv) is present. According to a particular embodiment of the invention, the process for treating keratin materials is a process, notably a cosmetic process, for treating keratin materials, in particular 25 for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or coloring keratin fibers, preferably the hair. According to a particular embodiment of the invention, the process for treating keratin materials is a cosmetic process for caring for, styling and / or coloring keratin fibers, preferably the hair. 30 According to another embodiment of the invention, the process for treating keratin materials is a skincare process. 12 According to another embodiment of the invention, the keratin material treatment process is a makeup process for the skin, the lips, the eyelashes and the eyebrows. According to this embodiment, the process comprises at least one cosmetic active agent chosen from dyestuffs, preferably pigments. 5 According to one aspect of the invention, the process for treating keratin materials according to the invention using ingredients i), optionally ii), optionally iv), and optionally v), is a process for coloring keratin fibers. According to another aspect of the invention, the process for treating keratin materials according to the invention using the ingredients i), optionally ii), optionally iv) and 10 optionally v), is a skincare process. According to one embodiment of the invention, the process according to the invention is a process for treating, notably for cosmetically treating, keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or coloring keratin fibers, preferably the hair, comprising the 15 application to said keratin materials of at least: - i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, or a composition, termed “C1”, comprising i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, the organic or mineral acid or base salts thereof, and / or the solvates thereof, such as the hydrates, as 20 defined previously and hereinbelow, and optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; preferably, composition “C1” does not comprise any ii) crosslinking agent; - a composition, termed “C2”, comprising i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, the organic or mineral acid or base 25 salts thereof, and / or the solvates thereof, such as the hydrates, as defined previously and hereinbelow, ii) at least one crosslinking agent, in particular as defined previously and hereinbelow, and optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; preferably, composition “C2” does not comprise iv) a cosmetic active agent; 30 - a composition, termed “C3”, comprising i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, the organic or mineral acid or base salts thereof, and / or the solvates thereof, such as the hydrates, as defined previously and 13 hereinbelow, ii) at least one crosslinking agent, in particular as defined previously and hereinbelow, and iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; - a composition, termed “C4”, comprising ii) at least one crosslinking agent, in 5 particular as defined previously and hereinbelow, and optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; preferably, composition “C4” does not comprise i) at least one polyester of formula (I), optical or geometrical isomers thereof, organic or mineral acid or base salts thereof, and / or solvates thereof, such as the hydrates, as defined previously and hereinbelow; and / or 10 - a composition, termed “C5”, comprising iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; preferably, composition “C5” does not comprise i) at least one polyester of formula (I), optical or geometrical isomers thereof, organic or mineral acid or base salts and / or solvates thereof, such as the hydrates, as defined previously and hereinbelow; and does not comprise ii) at least one crosslinking agent 15 as defined previously and hereinbelow; it being understood that the process uses i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow and that compositions “C1”, “C2”, “C3”, “C4” and / or “C5” may comprise v) one or more fatty substances, in particular at least one oil, which is preferably volatile, as defined previously 20 and hereinbelow, more preferably isododecane. According to one embodiment of the invention, the process according to the invention is a process for the treatment, in particular the cosmetic treatment, of keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or dyeing keratin fibers, preferably the hair, 25 comprising the application to said keratin materials of i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, included in a composition, termed “C1”, comprising i), optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; preferably, composition “C1” does not comprise ii) a crosslinking agent; or 30 - said polyester of formula (I) being included in a composition, termed “C2”, comprising i), ii) at least one crosslinking agent, in particular as defined previously and hereinbelow, and optionally iv) at least one cosmetic active agent, in particular as defined 14 previously and hereinbelow; preferably, composition “C2” does not comprise iv) a cosmetic active agent; or - said polyester of formula (I) being included in a composition, termed “C3”, comprising i), ii) at least one crosslinking agent, in particular as defined previously and 5 hereinbelow, iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow and preferably chosen from dyestuffs, preferably pigments, it being understood that compositions “C1”, “C2” and / or “C3” may comprise v) one or more fatty substances, in particular at least one oil, which is preferably volatile, as defined previously and hereinbelow, and more preferentially isododecane. 10 According to one embodiment of the invention, the process according to the invention is a process for the treatment, in particular the cosmetic treatment, of keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or coloring keratin fibers, preferably the hair, 15 comprising the application to said keratin materials of i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, included in a composition, termed “C2”, comprising i), ii) at least one crosslinking agent, in particular as defined previously and hereinbelow, and optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; and optionally v) one or 20 more fatty substances, in particular at least one oil, which is preferably volatile, as defined previously and hereinbelow, and more preferentially isododecane; preferably, composition “C2” does not comprise iv) any cosmetic active agent. According to one embodiment of the invention, the process according to the invention is a 25 process for the treatment, in particular the cosmetic treatment, of keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or coloring keratin fibers, preferably the hair, comprising the application to said keratin materials of i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, 30 included in a composition, termed “C3”, comprising i), ii) at least one crosslinking agent, in particular as defined previously and hereinbelow, iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow, preferably at least one dyestuff, more 15 preferentially at least one pigment, and optionally v) one or more fatty substances, in particular at least one oil, which is preferably volatile, as defined previously and hereinbelow, more preferentially isododecane. 5 According to one embodiment of the invention, the process according to the invention is a process for the treatment, in particular the cosmetic treatment, of keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or coloring keratin fibers, preferably the hair, comprising the application to said keratin materials of: 10 i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, included in a composition, termed “C1”, comprising i), optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; preferably, composition “C1” does not comprise ii) a crosslinking agent; and i) at least one crosslinking agent, in particular as defined previously and hereinbelow, 15 included in a composition, termed “C4”, comprising ii) at least one crosslinking agent, in particular as defined previously and hereinbelow, optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; preferably, composition “C4” does not comprise i) at least one polyester of formula (I), optical or geometrical isomers thereof, organic or mineral acid or base salts thereof, and / or solvates thereof, such as 20 hydrates, as defined previously and hereinbelow; and - optionally a composition, termed “C5”, comprising iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow; preferably, composition “C5” does not comprise i) at least one polyester of formula (I), optical or geometric isomers, organic or mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined 25 previously and hereinbelow, and does not comprise ii) at least one crosslinking agent, it being understood that compositions “C1”, “C4” and “C5” may comprise v) one or more fatty substances, in particular at least one oil, which is preferably volatile, as defined previously and hereinbelow, more preferentially isododecane. 30 According to one aspect of the invention, the process for treating keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or coloring keratin fibers, preferably the hair, 16 uses i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, the organic or mineral acid or base salts thereof, and / or the solvates thereof, such as hydrates, as defined previously and hereinbelow, or a composition comprising same; said composition “C1” optionally comprising iv) at least one cosmetic active agent, in particular 5 as defined hereinbelow, notably chosen from a) coloring agents, such as pigments, direct dyes, and mixtures thereof, b) active agents for caring for keratin materials, preferably the skin, c) UV-screening agents, and d) mixtures thereof, and notably at least one coloring agent, more particularly at least one pigment, and / or optionally v) at least one fatty substance; preferably, composition “C1” does not comprise ii) a crosslinking agent. 10 According to another aspect, the process for treating keratin materials according to the invention, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or dyeing keratin fibers, preferably the hair, uses a composition, termed “C2”, comprising i) at least one polyester of formula (I), and also the optical or geometrical isomers thereof, the organic or mineral acid or base salts 15 thereof, and / or the solvates thereof, such as the hydrates, as defined previously and hereinbelow, ii) at least one crosslinking agent, in particular as defined hereinbelow, and optionally iv) at least one cosmetic active agent, in particular as defined previously, and / or optionally v) at least one fatty substance; preferably, composition “C2” does not comprise iv) any cosmetic active agent. 20 According to another aspect, the process for treating keratin materials according to the invention, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or coloring keratin fibers, preferably the hair, uses a composition, termed “C3”, comprising i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, the organic or mineral acid or base salts thereof, 25 and / or the solvates thereof, such as the hydrates, as defined previously and hereinbelow, ii) at least one crosslinking agent, in particular as defined hereinbelow, iv) at least one cosmetic active agent, in particular as defined previously, and optionally v) at least one fatty substance. According to another aspect, the process for treating keratin materials according to the 30 invention, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or coloring keratin fibers, uses a composition termed “C1” or i) at least one polyester of formula (I) and also the optical or geometrical 17 isomers thereof, the organic or mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously and hereinbelow, and a composition termed “C4”, said composition “C1” comprising i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, the organic or mineral acid or base salts thereof, and / or 5 solvates thereof, such as hydrates, as defined previously and hereinbelow, and optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow, and / or optionally v) at least one fatty substance, in particular as defined previously and hereinbelow, and said composition “C4” comprising ii) at least one crosslinking agent, in particular as defined previously and hereinbelow, and optionally iv) at least one cosmetic 10 active agent, in particular as defined previously and hereinbelow, and / or optionally v) at least one fatty substance, in particular as defined previously and hereinbelow. According to another variant of the process of the invention, the ingredient(s) i), optionally iv), and optionally v) are applied together, i.e. simultaneously, to the keratin materials during a first step, then during a subsequent step, the ingredient(s) ii), optionally iv), and optionally 15 v) are applied to said materials. According to a particular embodiment, the process according to the invention comprises two successive steps in which two different compositions are applied to said keratin materials. According to a particular embodiment of the process, during the first step i), at least one polyester of formula (I) and also the optical or geometrical isomers thereof, organic or 20 mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously and hereinbelow, or a composition “C1” containing same is applied to the keratin materials, then a composition “C4” is applied to said keratin materials. According to yet another variant of the process of the invention, the ingredient(s) ii) and optionally iv) and / or v) are applied to the keratin materials, then the ingredient(s) i), and 25 optionally iv) at least one cosmetic active agent and / or v) at least one fatty substance, in particular as defined previously, are applied to said keratin materials. In particular, composition “C4” is applied to the keratin materials, then i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, organic or mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously and hereinbelow, or 30 a composition “C1” containing same is applied. According to another variant of the process according to the invention, i) or a composition “C1” containing i), said composition “C1” comprising v) optionally at least one oil, in 18 particular a volatile oil as defined previously and hereinbelow, preferably isododecane, is applied, and sequentially a composition “C4” containing ii), optionally iv), and optionally v), preferably i) or composition “C1” containing i) being applied before composition “C4”. According to a particular embodiment of the process, during the first step a composition 5 “C2” is applied to the keratin materials, then a composition “C4” is applied to said keratin materials. According to another variant of the process according to the invention, a composition “C2” containing i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, the organic or mineral acid or base salts thereof, and / or the solvates thereof, such as 10 hydrates, and ii) at least one crosslinking agent, optionally iv) at least one cosmetic active agent, and optionally v) at least one oil, in particular a volatile oil as defined previously and hereinbelow, preferably isododecane, is applied, and sequentially a composition “C4” containing ii) at least one crosslinking agent, optionally at least one cosmetic active agent iv), and optionally v) at least one oil, in particular a volatile oil as defined previously and 15 hereinbelow, is applied, composition “C2” preferably being applied before composition “C4”, and it being understood that the optional crosslinking agent(s) contained in composition “C2” may be identical to or different from the crosslinking agent(s) contained in composition “C4”; preferably, the crosslinking agent(s) are different. Compositions “C1”, “C2”, “C3”, “C4” and / or “C5” of the process according to the invention, 20 which comprise v) at least one fatty substance, notably at least one oil, and water, may be in the form of a direct or inverse emulsion. Compositions “C1”, “C2”, “C3”, “C4” and / or “C5” of the process according to the invention may thus be applied directly as such to the target keratin materials or may even be formed directly on the surface of these keratin materials. 25 According to the invention, three application methods known as the “one-action application mode”, the “two-action application mode” and the “three-action application mode” are thus distinguished. According to one embodiment of the process of the invention, the process is performed in one action by applying composition “C1”, “C2” or “C3”, as defined previously, to the keratin 30 materials. Thus, according to one embodiment, the treatment process according to the invention comprises a single step of applying i) at least one polyester of formula (I) and also the optical 19 or geometrical isomers thereof, organic or mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously and hereinbelow, or composition “C1,” or composition “C2,” or composition “C3” to said keratin materials; preferably, the treatment process according to the invention comprises either a single step of applying composition 5 “C2” or composition “C3” to said keratin materials; or two successive steps of applying to said keratin materials two different compositions, preferably composition “C1” then composition “C4”; or three successive steps of applying to said keratin materials three different compositions, preferably composition “C1” then composition “C4” then composition “C5”. 10 The term “one-action application mode” means the direct application to the target keratin materials of a single composition in accordance with the invention, namely composition “C1”, “C2” or “C3”. The term “one-action application mode” also means the single application of i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, organic or 15 mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously and hereinbelow. After application of composition “C1”, or i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, organic or mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously and hereinbelow, or of composition 20 “C2,” or of composition “C3,” a persistent and tack-free deposit is advantageously obtained. The deposit obtained is also glossy and resistant to edible oils, water, sebum and friction. According to another embodiment of the process of the invention, the process is performed in two actions. The term “two-action application mode” means the successive application, to the target 25 keratin material, of two different compositions, for example “C1” and “C4”, or “C2” and “C4”, or “C3” and “C4”. Preferably “C1” and then “C4”, “C2” and then “C4”, or “C3” and then “C4”. The term “two-action application mode” also means the sequential application to the target keratin material of i) at least one polyester of formula (I) and also the optical or geometrical 30 isomers thereof, organic or mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously and hereinbelow, and of a composition “C4”. According to another embodiment, the process of the invention is performed in three actions. 20 The term “three-action application mode” means the sequential application of three different compositions “C1” to “C5”. According to this application mode, for example, according to one embodiment, successive application is performed on the keratin materials, α) of a composition “C1”, then β) of a composition “C4”, then γ) of a composition “C5”, preferably 5 “C1” then “C4” or, respectively, “C5” or “C5” or, respectively, “C4”. According to another embodiment, sequential application is performed on the keratin materials, α) of a composition, for example “C4”, and β) of a composition “C1” or “C2”, and even γ) of a composition “C5”; preferably, composition “C4” is applied before composition “C1” or “C2”. 10 The term “three-action application mode” also means the sequential application of i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, organic or mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously and hereinbelow, of a composition “C4” and of a composition “C5”. In the two- or three-action application modes, the composition applied first, for example 15 “C1” or i), or “C2” is conventionally referred to as the “base coat”, and the composition(s) superposed thereon are generally referred to as the “top coat”. After application of the various compositions “C1”, or i), and “C2” to “C5”, a persistent, non-tacky deposit is advantageously obtained. The deposit obtained is also glossy and resistant to edible oils, water and shampoo washing. 20 According to a particular embodiment, the compositions are applied to dry keratin materials. According to a particular embodiment, the compositions are applied to damp or wet keratin materials, i.e. keratin materials containing water on the surface. According to a particular embodiment, the keratin materials are dried after application of compositions “C1”, or i), and “C2” to “C5”, in particular after application of each different 25 composition. The drying step may be performed with a drying device such as a hood, a hairdryer or a Climazon, more preferentially a hair dryer. When the drying step is performed with a hood or a hair dryer, the drying temperature is greater than or equal to 40°C and strictly below 120°C. During the drying of the keratin fibers, a mechanical action may be exerted on the locks, 30 such as combing, brushing or running the fingers through. This operation may similarly be performed once the hair has dried, naturally or otherwise. 21 After the keratin fiber drying step, a step of forming the keratin fibers into shape may be performed with a straightening iron, a crimping or curling iron, a steam iron or a heated comb, preferably a straightening iron, a crimping or curling iron or a steam iron, more preferentially a steam iron. Preferably, the shaping step is performed at a temperature 5 ranging from 150°C to 230°C, more preferentially from 160°C to 210°C, even more preferentially from 180°C to 210°C. The iron can be applied to the keratin fibers in successive separate strokes ranging 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, or by 10 gradually moving or sliding it along the hair. Preferably, the iron is applied in a continuous movement from the root to the end of the hair, in one or more passes. According to one aspect, the present invention relates to a process for the treatment, in particular the cosmetic treatment, of keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling 15 and / or dyeing keratin fibers, preferably the hair, comprising a step of applying to the keratin fibers i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, organic or mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously and hereinbelow, or a composition “C1” containing same, or a composition “C2” or a composition “C3”, in particular containing at least one dyestuff, in 20 particular as defined previously, and more particularly at least one pigment. According to one aspect, the present invention relates to a process, notably a cosmetic process, for treating keratin materials, notably the skin and / or the lips and / or the eyelashes and / or the eyebrows, in particular for caring for and / or making up the keratin materials, notably the skin, the lips, the eyelashes and / or the eyebrows, comprising a step of applying 25 to said keratin materials, notably said skin or said lips or said eyelashes or said eyebrows, a composition “C3”, notably containing at least one dyestuff, in particular as defined previously, and more particularly at least one pigment. According to another of its aspects, the present invention relates to a cosmetic treatment process for caring for and / or making up keratin materials, notably the skin, the lips, the 30 eyelashes and / or the eyebrows, comprising the successive application of at least: - i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, or a composition, termed “C1” comprising same and 22 optionally comprising iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow, and / or optionally v) at least one fatty substance, in particular as defined previously and hereinbelow; and then - a composition, termed “C4”, comprising ii) at least one crosslinking agent, in particular 5 as defined hereinbelow, optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow, and / or optionally v) at least one fatty substance, in particular as defined previously and hereinbelow; at least one of the compositions “C1” and / or “C4” containing at least one dyestuff, in particular as defined previously and hereinbelow, preferably at least one pigment, and more 10 preferentially composition “C1” comprises at least one pigment. According to another of its aspects, the present invention relates to a cosmetic process for treating keratin materials, notably for caring for and / or making up keratin materials, notably the skin, the lips, the eyelashes and / or the eyebrows, comprising the sequential application of at least: 15 - i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, or a composition “C1” as defined previously; and - a composition “C4” as defined previously; and - a composition “C5” as defined previously; and it being understood that compositions “C1” and / or “C4” and / or “C5” contain at least one 20 dyestuff in particular as defined hereinbelow, preferably at least one pigment. Preferably, composition “C5” comprises at least one pigment. According to another of its aspects, the present invention relates to a cosmetic process for the treatment of keratin fibers, in particular for caring for, styling and / or coloring keratin fibers, preferably the hair, comprising the successive application to said keratin fibers of at 25 least: - i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, or a composition, termed “C1” containing same and optionally comprising iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow, and / or optionally v) at least one fatty substance, in particular as 30 defined previously and hereinbelow; preferably, composition “C1” does not comprise ii) any crosslinking agent; and then 23 - a composition, termed “C4”, comprising ii) at least one crosslinking agent, in particular as defined previously and hereinbelow, optionally iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow, and / or optionally v) at least one fatty substance, in particular as defined previously and hereinbelow; preferably, composition 5 “C4” does not comprise i) at least one polyester of formula (I), optical or geometrical isomers thereof, organic or mineral acid or base salts and / or solvates thereof, such as the hydrates, as defined previously and hereinbelow; at least one of the compositions “C1” and / or “C4” containing at least one dyestuff, in particular as defined previously and hereinbelow, preferably at least one pigment, and more 10 preferentially composition “C1” comprises at least one pigment. According to another of its aspects, the present invention relates to a cosmetic process for treating keratin fibers, in particular for caring for, styling and / or coloring keratin fibers, preferably the hair, comprising the successive application of at least: - i) at least one polyester of formula (I) comprising at least two acetoacetate functions as 15 defined previously and hereinbelow, or a composition “C1” or “C2” or “C3” as defined previously; and / or - a composition “C4” as defined previously; it being understood that the process uses together or separately i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and 20 hereinbelow, and that the compositions “C1”, “C2”, “C3” and / or “C4” may be anhydrous, aqueous such as aqueous-alcoholic and / or comprise one or more fatty substances v), in particular as described hereinbelow. According to another of its aspects, the present invention relates to a cosmetic process for treating keratin fibers, in particular for caring for, styling and / or coloring keratin fibers, 25 preferably the hair, comprising the sequential application of at least: - i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, or a composition “C1” as defined previously; and then - a composition “C4” as defined previously; and then - a composition “C5” as defined previously; 30 it being understood that compositions “C1” and / or “C4” and / or “C5” contain at least one dyestuff in particular as defined hereinbelow, preferably at least one pigment. Preferably, composition “C5” comprises at least one pigment. 24 According to another of its aspects, the present invention relates to a cosmetic process for treating keratin fibers, in particular for caring for, styling and / or coloring keratin fibers, preferably the hair, comprising the successive application of at least: - a composition “C2” or “C3” as defined previously; and 5 - a composition “C4” as defined previously; it being understood that compositions “C2” or “C3” contain at least iv) one dyestuff, in particular as defined hereinbelow, and / or composition “C4” contains at least one dyestuff, in particular as defined hereinbelow; preferably composition “C2” or “C3” comprises at least one pigment. 10 According to another of its aspects, the present invention relates to a cosmetic treatment process for dyeing keratin fibers, notably the hair, and / or for making up keratin materials, notably the skin, comprising the application to said keratin materials of at least: - a composition, termed “C2” as defined previously, or a composition, termed “C3” as defined previously; 15 it being understood that the compositions “C2” or “C3” may comprise v) one or more fatty substances. According to another of its aspects, the present invention relates to a cosmetic process for the treatment of keratin fibers, for styling keratin fibers, preferably the hair, comprising the application to said keratin fibers of at least: 20 - i) at least one polyester of formula (I) comprising at least two acetoacetate functions as defined previously and hereinbelow, or a composition “C1” as defined previously; preferably, composition “C1” does not comprise any ii) crosslinking agent; or - a composition termed “C2” as defined previously; - a composition termed “C3” as defined previously; 25 it being understood that the compositions “C1” or “C2” or “C3” may comprise v) one or more fatty substances. COMPOUNDS OF FORMULA (I) As indicated above, the treatment process according to the invention involves applying to 30 keratin materials at least one polyester of formula (I) comprising at least two acetoacetate functions, and also the optical or geometrical isomers thereof, and / or solvates thereof, such as hydrates, or a composition containing same. 25 Thus, the treatment process according to the invention involves applying to keratin materials at least one polyester of formula (I) comprising at least two acetoacetate functions, and also the optical or geometrical isomers thereof, and / or solvates thereof, such as hydrates, or a composition containing same: 5 (Z)–[O-C(O)-C(Ra)(Rb)-C(O)-R4]u(I) in which formula (I): - Z denotes a multivalent radical derived: from an alkyd resin (A) obtained by reaction of: - from 10% to 62% by mass of at least one polyol; 10 - from 10% to 62% by mass of at least one polyacid; - from 35% to 60% by mass of at least one fatty alcohol and / or at least one fatty monoacid; and - from 0% to 20% by mass of at least one monocarboxylic acid; the mass percentages being expressed relative to the total weight of the alkyd resin (A); 15 or an alkyd resin (B) obtained by reacting an ethylenically unsaturated alkyd resin (A) with at least one (poly)hydroxy thiol; - u is an integer greater than 2; - R4 represents a linear or branched, saturated or unsaturated C1-C6 monovalent hydrocarbon- 20 based radical, preferably a (C1-C4)alkyl group, in particular methyl or tert-butyl, more preferentially methyl; - Ra and Rb, which may be identical or different, represent a hydrogen atom or a (C1-C4)alkyl group, preferably a hydrogen atom; and ii) optionally at least one crosslinking agent. 25 Preferably, the polyesters of formula (I) are such that all the radicals O-C(O)-C(Ra)(Rb)- C(O)-R4 are identical. Preferably, the molecular weight of the alkyd resin (A) or (B) used in the preparation of the polyesters of formula (I) is between 500 and 80000 g / mol. Preferably, the molecular weight of the polyesters of formula (I) according to the invention 30 is between 600 and 100000 g / mol. Preferably, the mass ratio between the alkyd resin (A) or (B) used in the preparation of the polyesters of formula (I) and the polyester(s) of formula (I) is between 65 and 95. 26 Preferably, the mass ratio between the units -O-C(O)-C(Ra)(Rb)-C(O)-R4and the polyester(s) of formula (I) is between 5 and 35 in the polyester(s) of formula (I) according to the invention. Preferably, the mass ratio between the alkyd resin (A) or (B) used in the preparation of the 5 polyesters of formula (I) and the units -O-C(O)-C(Ra)(Rb)-C(O)-R4ranges between 65 / 35 and 95 / 5 in the polyester(s) of formula (I) according to the invention. According to a particular embodiment of the invention, (Z) represents a multivalent radical comprising from 40 to 6000 carbon atoms, terminated by m radicals -O- and n radicals - C(O)ORz, with: 10 - m being an integer greater than 2, preferably greater than or equal to 10, - n being an integer greater than or equal to zero, - Rz being a hydrogen atom or an alkyl group comprising from 4 to 40 atoms, notably from 5 to 32 atoms, and more preferentially from 6 to 24 carbon atoms, said multivalent radical being cyclic or acyclic, branched, saturated or unsaturated, 15 interrupted with several ester radicals -O-C(O)- or -C(O)-O-, and optionally interrupted with one or more non-adjacent sulfur atoms S. More particularly, the radical(s) -C(O)ORz are chosen from t-butyl esters or oleyl esters, and esters of caprylic acid, 2-ethylhexanoic acid, 4,5-dimethylhexanoic acid, 2-heptylheptanoic acid, 3,5,5-trimethylhexanoic acid, octanoic acid, isooctanoic acid, nonanoic acid, decanoic 20 acid, isononanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid, cerotic acid (hexacosanoic acid), 3- cyclopentylpropionic acid, 3-cyclohexylpropionic acid, cyclohexylacetic acid, 4- cyclohexylbutyric acid, caproleic acid, undecylenic acid, dodecylenic acid, myristoleic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, elaidic acid, gondoic acid or erucic 25 acid. Alkyd resins (A) The alkyd resin(s) (A) used in the preparation of the polyesters of formula (I) are obtained by reacting: 30 - from 10% to 62% by mass of at least one polyol; - from 10% to 62% by mass of at least one polyacid; 27 - from 35% to 60% by mass of at least one fatty alcohol and / or at least one fatty monoacid; and - from 0% to 20% by mass of at least one monocarboxylic acid; the mass percentages being expressed relative to the total weight of the alkyd resin (A). 5 Thus, the alkyd resin(s) (A) used in the preparation of the polyesters of formula (I) may be obtained after a one-step polycondensation reaction. Preferably, the hydroxyl number of the alkyd resin(s) (A) obtained is between 50 and 300 mg KOH / g. Preferably, the acid number of the alkyd resin(s) (A) obtained is between 0 and 15 mg 10 KOH / g. Preferably, the polycondensation synthesis of the alkyd resin(s) (A) is performed without a solvent. Preferably, the polycondensation is performed under an inert atmosphere such as an argon atmosphere. 15 Preferably, the polycondensation is performed at a temperature of between 160°C and 270°C, and more preferentially between 170°C and 260°C for a period of between 1h and 24h. According to a first embodiment variant of the invention, the alkyd resin(s) (A) are obtained by a one-step polycondensation of: 20 - 0% to 12% by mass of at least one diol; - 20% to 50% by mass of at least one compound including at least 3 alcohol functions; - 10% to 30% by mass of at least one dicarboxylic acid compound; - 0% to 17% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 10% by mass of at least one monocarboxylic acid compound; and 25 - 35% to 60% by mass of at least one fatty monoacid; the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to this variant, the hydroxyl number of the alkyd resin(s) (A) obtained is between 50 and 300 mg KOH / g. According to a second embodiment variant of the invention, the alkyd resin(s) (A) are 30 obtained by a one-step polycondensation of: - 10% to 30% by mass of at least one diol; and - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; and 28 - 0% to 12% by mass of at least one dicarboxylic acid compound; and - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid functions; and - 0% to 20% by mass of at least one monocarboxylic acid compound; and 5 - 35% to 60% by mass of at least one fatty alcohol; the mass percentages being expressed relative to the total weight of the alkyd resin (A), it being understood that at least one of the dicarboxylic acid compounds and compounds including at least 3 carboxylic acid functions, and / or at least one of the fatty alcohols, contains at least one ethylenic unsaturation. 10 Preferably, the hydroxyl number of the alkyd resin(s) (A) obtained is between 50 and 800 mg KOH / g. Preferably, the dicarboxylic acid(s) comprising at least one ethylenic unsaturation are chosen from maleic acid, fumaric acid, muconic acid and itaconic acid. Preferably, the compound(s) including at least 3 carboxylic acid functions and comprising 15 at least one ethylenic unsaturation are chosen from tricarboxylic acids such as cyclohexanetricarboxylic acid, trimellitic acid, 1,2,3-benzenetricarboxylic acid, 1,3,5- benzenetricarboxylic acid; citric acid, tetracarboxylic acids such as butanetetracarboxylic acid, pyromellitic acid and mixtures thereof; preferably from tricarboxylic acids; more preferably from citric acid. 20 Preferably, the fatty alcohol(s) comprising at least one ethylenic unsaturation are chosen from 9-decen-1-ol, citronellol, oleyl alcohol, linoleic alcohol and mixtures thereof, more preferentially oleyl alcohol. According to one embodiment of this variant, the alkyd resin(s) (A) are obtained by a one- step polycondensation of: 25 - 10% to 30% by mass of at least one diol; - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; - 0% to 12% by mass of at least one dicarboxylic acid compound; - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid functions; 30 - 0% to 20% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty alcohol, which is preferably saturated; 29 the mass percentages being expressed relative to the total weight of the alkyd resin (A), it being understood that at least one of the dicarboxylic acid compounds and compounds including at least 3 carboxylic acid functions, preferably at least one of the dicarboxylic acid compounds, contains at least one ethylenic unsaturation. 5 According to another embodiment of this variant, the alkyd resin(s) (A) are obtained by a one-step polycondensation of: - 10% to 30% by mass of at least one diol; - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; - 0% to 12% by mass of at least one dicarboxylic acid compound; 10 - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 20% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty alcohol; the mass percentages being expressed relative to the total weight of the alkyd resin (A), it 15 being understood that at least one of the dicarboxylic acid compounds and compounds including at least 3 carboxylic acid functions, preferably at least one of the dicarboxylic acid compounds, and at least one of the fatty alcohols contains at least one ethylenic unsaturation. According to a preferred embodiment of this variant, the alkyd resin(s) (A) are obtained by a one-step polycondensation of: 20 - 10% to 30% by mass of at least one diol; - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; - 0% to 12% by mass of at least one dicarboxylic acid compound, which is preferably saturated; - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid 25 functions, which is preferably saturated; - 0% to 20% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty alcohol; the mass percentages being expressed relative to the total weight of the alkyd resin (A), it being understood that at least one of the fatty alcohols contains at least one ethylenic 30 unsaturation. Preferably, the alkyd resin(s) (A) used in the preparation of the polyesters of formula (I) according to the invention are formed by polycondensation of: 30 a) at least one fatty alcohol and / or at least one fatty monoacid, b) at least one polyol, c) at least one dicarboxylic acid compound and / or compound including at least 3 carboxylic acid functions, 5 d) optionally at least one monocarboxylic acid compound. Fatty alcohols According to one embodiment, the alkyd resin(s) (A) are obtained by a polycondensation step using at least one fatty alcohol. 10 The term “fatty alcohol” refers to a saturated or unsaturated, linear or branched, or cyclic monoalcohol comprising from 8 to 32 carbon atoms, notably from 10 to 28 carbon atoms, better still from 14 to 20 carbon atoms. Needless to say, it is possible to use a mixture of such alcohols, provided that at least one fatty alcohol contains at least one ethylenic unsaturation. 15 Preferably, the fatty alcohol(s) are chosen from saturated or unsaturated, linear or branched monoalcohols comprising from 8 to 32 carbon atoms, notably from 10 to 28 carbon atoms, better still from 14 to 20 carbon atoms, it being understood that at least one fatty alcohol contains at least one ethylenic unsaturation. In particular, the fatty alcohol(s) may be chosen from saturated fatty monoalcohols, more 20 preferentially from octan-1-ol, nonan-1-ol, decan-1-ol, dodecan-1-ol, tetradecan-1-ol, hexadecan-1-ol, octadecanol, docosanol, triacontanol, octan-2-ol, 2-butyloctanol, hexyldecanol, 2-octyldecanol and / or unsaturated monoalcohols, in particular 9-decen-1-ol, citronellol, oleyl alcohol, linoleyl alcohol and mixtures thereof. Advantageously, the alkyd resin(s) (A) are obtained by a polycondensation step using one 25 or more fatty alcohols comprising from 10 to 28 carbon atoms, better still comprising from 14 to 20 carbon atoms. More advantageously, the alkyd resin(s) (A) are obtained by a polycondensation step using one or more unsaturated, preferably monounsaturated, fatty alcohols. Even more advantageously, the alkyd resin(s) (A) are obtained by a polycondensation step using one or 30 more unsaturated fatty alcohols, one of which is oleyl alcohol. 31 Preferably, the alkyd resin(s) (A) are obtained by a polycondensation step using a single fatty alcohol containing at least one ethylenic unsaturation, preferably a single ethylenic unsaturation. Preferentially, the fatty alcohol used is oleyl alcohol. 5 According to another embodiment, the alkyd resin(s) (A) are obtained by polycondensation: - of at least one diol; - of at least one compound including at least three carboxylic acid functions; and - of at least one fatty alcohol; it being understood that at least one fatty alcohol contains at least one ethylenic unsaturation, 10 said polycondensation being able to optionally involve at least one compound including at least 3 alcohol functions, optionally at least one dicarboxylic acid compound, and optionally at least one monocarboxylic acid compound. According to a preferred embodiment, the alkyd resin(s) (A) are obtained by polycondensation: 15 - of at least one fatty alcohol, at least one of which contains at least one ethylenic unsaturation; and - of at least one compound including at least three carboxylic acid functions; and - of at least one diol; more preferentially: by polycondensation of oleyl alcohol, at least one compound including 20 at least 3 carboxylic acid functions, and at least one diol; even more preferentially by polycondensation of: - from 35% to 60% by mass, such as 50% by mass, of oleyl alcohol; - from 20% to 50% by mass, preferably from 20% to 30% by mass, more preferentially from 25% to 30% by mass, of at least one compound including at least 3 carboxylic acid functions, 25 such as citric acid; and - from 10% to 30% by mass, preferably from 20% to 30% by mass, more preferentially from 20% to 25% by mass, of at least one diol, such as 1,10-decanediol; the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to another embodiment, the alkyd resin(s) (A) are obtained without the use of 30 fatty alcohol. Polyols 32 The alkyd resin(s) (A) are obtained by one-step polycondensation of 10% to 62% by mass of at least one polyol, the mass percentages being expressed relative to the total weight of the alkyd resin (A). The term “polyol” means an organic compound comprising from 2 to 8 hydroxyl groups, 5 preferentially from 3 to 6 hydroxyl groups. The polyols used for the preparation of the alkyd resin(s) (A) are advantageously saturated or unsaturated, linear, branched or cyclic compounds comprising from 2 to 50 carbon atoms, notably from 6 to 40 carbon atoms, and more preferentially from 8 to 37 carbon atoms, optionally comprising one or more non-adjacent oxygen atoms intercalated between two 10 carbon atoms, and comprising from 2 to 8 hydroxyl groups. Preferably, a polyol used for the preparation of the alkyd resin(s) (A) does not comprise any acid functions, amine functions or thiol functions. Among the polyols, a distinction is made between: diols, which comprise 2 hydroxyl groups, and compounds including at least 3 alcohol functions, notably 3 to 6 alcohol functions. 15 According to one embodiment, the alkyd resin(s) (A) are obtained by a one-step polycondensation involving 10% to 62% by mass of at least one polyol, the at least one polyol containing 0 to 30% by mass of at least one diol, the mass percentages being expressed relative to the total weight of the alkyd resin (A). 20 According to a preferred embodiment, the diol(s) are saturated. A diol used for the preparation of the alkyd resin(s) (A) is preferably chosen from: isosorbide, hexamethylene glycol, hexylene glycol, hexanediol, neopentyl glycol, 1,2- propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4- butanediol, 2,4-butanediol, 3,4-butanediol, 1,4-pentanediol, 1,5-pentanediol, 2,2,4- 25 trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,2-octanediol, 1,8-octanediol, 1,10-decanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, isoprene glycol, 1,12- octadecanediol, 1,10-decanediol, 1,16-hexadecanediol, 1,12-dodecanediol, Pripol 2033 (18,18’-oxybis[(9Z,12Z)-9,12-octadecadiene-1-ol]), or from oligomers including 2 alcohol functions such as polypropanediol with Mw ranging from 100 to 1000, and also mixtures 30 thereof. 33 Preferentially, the diol(s) are chosen from 1,10-decanediol, Pripol 2033 and mixtures thereof. According to another embodiment, the alkyd resin(s) (A) are obtained following the use of 1% to 30% by mass, preferably 4% to 25% by mass, of at least one diol relative to the total 5 weight of the alkyd resin (A), preferably chosen from Pripol 2033, 1,10-decanediol, and mixtures thereof. According to one embodiment, the alkyd resin(s) (A) are obtained by polycondensation of: - 0% to 12% by mass, preferably 0% to 10% by mass, of at least one diol, preferably a single diol; 10 - 20% to 50% by mass of at least one compound including at least 3 alcohol functions; - 10% to 30% by mass of at least one dicarboxylic acid compound; - 0% to 17% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 10% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty monoacid; 15 the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to yet another embodiment, the alkyd resin(s) (A) are obtained by polycondensation of: - 10% to 30% by mass, preferably 15% to 28% by mass, more preferentially 18% to 26% by mass, of at least one diol, preferably a single diol; 20 - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; - 0% to 12% by mass of at least one dicarboxylic acid compound; - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 20% by mass of at least one monocarboxylic acid compound; and 25 - 35% to 60% by mass of at least one fatty alcohol, at least one of which contains at least one ethylenic unsaturation; the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to one embodiment, the alkyd resin(s) (A) are obtained without the use of diol. 30 According to one embodiment, the alkyd resin(s) (A) are obtained by a polycondensation step involving 10% to 62% by mass of at least one polyol, said at least one polyol containing 34 0% to 50% by mass of at least one compound including at least 3 alcohol functions, the mass percentages being expressed relative to the total weight of the alkyd resin (A). The compound(s) including at least 3 alcohol functions, notably 3 to 6 alcohol functions, may notably be linear, branched or cyclic, saturated or unsaturated, carbon-based 5 compounds, notably hydrocarbon-based compounds, comprising from 3 to 36 carbon atoms, notably from 3 to 24, or even from 4 to 18 carbon atoms, or even 5 to 10 carbon atoms and from 3 to 8 hydroxyl groups (OH), more preferentially from 3 to 6 hydroxyl groups, and which may also comprise one or more non-adjacent oxygen atoms intercalated between two carbon atoms (ether function). 10 According to a preferred embodiment, the compound(s) including at least 3 alcohol functions are saturated. The compound(s) including at least 3 alcohol functions, notably 3 to 6 alcohol functions, used for the preparation of the alkyd resin(s) (A) are chosen from: - triols, such as glycerol or trimethylolpropane; 15 - tetraols, such as pentaerythritol (tetramethylolmethane), erythritol or diglycerol; - pentols such as xylitol or triglycerol; - hexols such as sorbitol, mannitol or dipentaerythritol; and mixtures thereof. Preferably, the compound(s) including at least 3 alcohol functions, notably 3 to 6 alcohol 20 functions, are chosen from the tetraols, pentols, hexols and mixtures thereof. More preferentially, the compound(s) including at least 3 alcohol functions, notably 2 to 6 alcohol functions, are chosen from pentaerythritol, xylitol, dipentaerythritol and mixtures thereof. According to one embodiment, the alkyd resin (A) is obtained following the use of 1% to 25 50% by mass, preferably 4% to 50% by mass, more preferentially 15% to 40% by mass of at least one compound including at least 3 alcohol functions, preferably chosen from pentaerythrityl, xylitol, dipentaerythritol and mixtures thereof, the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to one embodiment, the alkyd resin(s) (A) are obtained by polycondensation of: 30 - 0% to 12% by mass, preferably 0% to 10% by mass, of at least one diol, preferably a single diol; 35 - 20% to 40% by mass of at least one compound including at least 3 alcohol functions, preferably chosen from pentaerythritol, xylitol, dipentaerythritol and mixtures thereof; - 10% to 30% by mass of at least one dicarboxylic acid compound; - 0% to 17% by mass of at least one compound including at least 3 carboxylic acid functions; 5 - 0% to 10% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty monoacid; the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to yet another embodiment, the alkyd resin(s) (A) are obtained by polycondensation of: 10 - 10% to 30% by mass, preferably 15% to 28% by mass, more preferentially 18% to 26% by mass, of at least one diol, preferably a single diol; - 0% to 12% by mass, preferably 0% by mass, of at least one compound including at least 3 alcohol functions; - 0% to 12% by mass of at least one dicarboxylic acid compound; 15 - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 20% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty alcohol, at least one of which contains at least one ethylenic unsaturation; 20 the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to one embodiment, the alkyd resin (A) is obtained without using a compound including at least three alcohol functions. Monocarboxylic acids 25 The alkyd resin(s) (A) are obtained by a polycondensation step using 0% to 20% by mass of at least one monocarboxylic acid compound, the mass percentages being expressed relative to the total weight of the alkyd resin (A). The term “monoacid” means an aromatic or non-aromatic monocarboxylic acid or its cyclic lactone form. 30 The term “aromatic monoacid” means a monocarboxylic acid borne by an aromatic (poly)cycle, said (poly)cycle being optionally substituted with one or more C1-C7alkyl and / or C1-C7 alkoxy radicals. 36 Among the aromatic monocarboxylic acids that may be used in the context of the invention, mention may be made of benzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, 1-naphthoic acid, 2-naphthoic acid, 4-tert-butylbenzoic acid, 1-methyl-2-naphthoic acid, 2-isopropyl-1- naphthoic acid, and mixtures thereof. 5 The term “non-aromatic monocarboxylic acid” means a saturated or unsaturated, linear, branched or cyclic monocarboxylic acid, optionally in its esterified or lactone form, comprising from 1 to 7 carbon atoms, notably from 2 to 7 carbon atoms and better still from 3 to 7 carbon atoms. Needless to say, a mixture of such acids may be used. Preferably, the term “non-aromatic monocarboxylic acid” refers to a saturated, linear or 10 branched monocarboxylic acid, optionally in its lactone form, comprising 5 to 7 carbon atoms. Among the non-aromatic monocarboxylic acids that may be used in the context of the invention, mention may be made preferentially of: hexanoic acid, epsilon-caprolactone. According to one embodiment, the alkyd resin (A) is obtained following the use of at least 15 one monocarboxylic acid or at least one lactone, preferably chosen from benzoic acid, hexanoic acid, epsilon-caprolactone and mixtures thereof. Preferably, the mass concentration of the monocarboxylic acid or lactone is less than or equal to 10% by mass, the mass percentages being expressed relative to the total weight of the alkyd resin (A). 20 According to a preferred embodiment, the polycondensation leading to the alkyd resin (A) does not involve a monocarboxylic acid. According to one embodiment, the alkyd resin(s) (A) are obtained by a polycondensation step using 35% to 60% by mass of at least one fatty monoacid relative to the total weight of 25 the alkyd resin (A). The term “fatty monoacid” refers to a saturated or unsaturated, linear, branched or cyclic monocarboxylic acid, optionally in its esterified form such as C1-C7alkyl esters or in anhydride form, comprising from 8 to 40 atoms, notably from 8 to 32 atoms, and more 30 preferentially from 8 to 24 carbon atoms. In the composition of the invention, when at least one fatty monoacid is used, it is necessarily different from the monocarboxylic acids. 37 Preferably, the fatty monoacids do not bear an amine function and do not bear any hydroxyl functions. Among the fatty monoacids that may be used in the context of the invention, the following may be mentioned, alone or as a mixture: 5 - saturated fatty acids such as caprylic acid, 2-ethylhexanoic acid, 4,5-dimethylhexanoic acid, 2-heptylheptanoic acid, 3,5,5-trimethylhexanoic acid, octanoic acid, isooctanoic acid, nonanoic acid, decanoic acid, isononanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid, cerotic acid (hexacosanoic acid), 10 - cyclic fatty acids such as 3-cyclopentylpropionic acid, 3-cyclohexylpropionic acid, cyclohexylacetic acid, 4-cyclohexylbutyric acid, - unsaturated fatty acids such as caproleic acid, undecylenic acid, dodecylenic acid, myristoleic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, elaidic acid, gondoic acid, erucic acid. 15 Preferably, the fatty acids are chosen from octanoic acid, lauric acid, oleic acid, isostearic acid such as the product sold by the company Croda under the name Prisorine 3505-LQ- (GD), and more particularly isostearic acid. According to another embodiment, the alkyd resins (A) are obtained by a polycondensation step using 37% to 59% by mass, more preferentially 40% to 58% by mass, of at least one 20 fatty monoacid relative to the total weight of the alkyd resin (A). According to a particular embodiment, the alkyd resin(s) (A) are obtained by a one-step polycondensation of: - 0% to 12% by mass, preferably 0% to 10% by mass, of at least one diol; and - 20% to 50% by mass of at least one compound including at least 3 alcohol functions; 25 - 10% to 30% by mass of at least one dicarboxylic acid compound; - 0% to 17% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 10% by mass, preferably 0% by mass, of at least one monocarboxylic acid compound; and - 35% to 60% by mass, preferably 37% to 59% by mass, more preferentially 40% to 58% by 30 mass, of at least one fatty monoacid; the mass percentages being expressed relative to the total weight of the alkyd resin (A). 38 According to one embodiment, the alkyd resins (A) are obtained without the use of a fatty monoacid. Polyacid compounds 5 The alkyd resin(s) (A) are obtained by a polycondensation step using 10% to 62% by mass of at least one polyacid, the mass percentages being expressed relative to the total weight of the alkyd resin (A). The term “polyacid” means an organic compound comprising 2 to 8 carboxylic acid functional groups, preferably 2 to 6 carboxylic acid functions, anhydride compounds also 10 featuring among the polyacids for the purposes of the invention; and in particular dicarboxylic acid compounds and compounds including at least 3 carboxylic acid functions of the invention. Preferably, a polyacid does not comprise any amine functions. Preferably, the polyacids are saturated or unsaturated, linear, branched or cyclic organic 15 compounds comprising from 2 to 40 carbon atoms, notably from 6 to 36 carbon atoms and more preferentially from 8 to 24 carbon atoms, optionally one or more non-adjacent oxygen atoms intercalated between two carbon atoms, and bearing from 2 to 8 carboxylic acid functions, preferably from 2 to 6 carboxylic acid functions. Among the polyacids, a distinction is made between diacids including two carboxylic acid 20 functions and acids including at least 3 carboxylic acid functions, such as those including 3 to 6 carboxylic acid functions. According to one embodiment, the alkyd resin(s) (A) are obtained by a polycondensation step using from 10% to 62% by mass of at least one polyacid, said at least one polyacid 25 containing 0% to 30% by mass of at least one dicarboxylic acid, the mass percentages being expressed relative to the total weight of the alkyd resin (A). The dicarboxylic acid(s) may be saturated or unsaturated, linear or branched, cyclic, aromatic or non-aromatic aliphatic acids, or in cyclic anhydride form, and may comprise from 2 to 40 carbon atoms, notably from 3 to 36 carbon atoms, or even from 4 to 24 carbon 30 atoms. When the diacids are in anhydride form, they preferably comprise from 8 to 12 carbon atoms. Said cyclic anhydride of a diacid may notably correspond to one of the following formulae: 39 in which the groups A and B are, independently of each other: - a hydrogen atom; - an aliphatic, saturated or unsaturated, linear, branched and / or cyclic carbon-based radical, 5 or an aromatic radical, comprising from 1 to 16 carbon atoms, notably from 2 to 10 carbon atoms, or even from 4 to 8 carbon atoms, notably methyl or ethyl; - or alternatively A and B, taken together, form a saturated or unsaturated, or even aromatic, ring comprising in total 5 to 7 and notably 6 carbon atoms. Among the diacids or anhydrides thereof that may be used, mention may be made, alone or 10 as a mixture, of: - dicarboxylic acids such as Pripol 1009, decanedioic acid, dodecanedioic acid, cyclopropanedicarboxylic acid, cyclohexanedicarboxylic acid, cyclobutanedicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-2,3-dicarboxylic acid, naphthalene- 2,6-dicarboxylic acid, suberic acid, oxalic acid, malonic acid, succinic acid, phthalic acid, 15 terephthalic acid, isophthalic acid, pimelic acid, sebacic acid, azelaic acid, homophthalic acid, adipic acid, fumaric acid, maleic acid, muconic acid, itaconic acid. Preferably, the diacid(s) are chosen from sebacic acid, adipic acid, homophthalic acid, and mixtures thereof. 20 According to one embodiment, the alkyd resin(s) (A) are obtained by a polycondensation step using from 10% to 62% by mass of at least one polyacid, said at least one polyacid containing 10% to 30% by mass of at least one dicarboxylic acid, the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to one embodiment, the alkyd resin(s) (A) are obtained by polycondensation of: 25 - 0% to 12% by mass, preferably 0% to 10% by mass, of at least one diol; - 20% to 50% by mass of at least one compound including at least 3 alcohol functions; - 10% to 30% by mass, preferably 12% to 29% by mass, of at least one dicarboxylic acid compound preferably chosen from sebacic acid, adipic acid, homophthalic acid, and mixtures thereof; 30 - 0% to 17% by mass of at least one compound including at least 3 carboxylic acid functions; 40 - 0% to 10% by mass, preferably 0%, of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty monoacid; the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to another embodiment, the alkyd resin(s) (A) are obtained by polycondensation 5 of: -10% to 30% by mass, preferably 20% to 30% by mass, of at least one diol; - 0% to 12% by mass, preferably 0% by mass, of at least one compound including at least 3 alcohol functions; - 0% to 12% by mass, preferably 0% by mass, of at least one dicarboxylic acid compound; 10 - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 20% by mass, preferably 0% by mass, of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty alcohol, at least one of which contains at least 15 one ethylenic unsaturation; the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to one embodiment, the alkyd resin(s) (A) are obtained without the use of a dicarboxylic acid. 20 The alkyd resin(s) (A) are obtained via a polycondensation step involving from 10% to 62% by mass of at least one polyacid, said at least one polyacid containing from 0% to 50% by mass of at least one compound including at least 3 carboxylic acid functions, the mass percentages being expressed relative to the total weight of the alkyd resin (A). The term “acid including at least 3 carboxylic acid functions” means a saturated or 25 unsaturated, even aromatic, linear, branched or cyclic polycarboxylic acid comprising at least 3 carboxylic COOH groups, such as those including 3 to 6 carboxylic acid functions, notably 3 to 5 COOH groups. The acid(s) including at least 3 carboxylic acid functions may notably be chosen from linear, branched and / or cyclic, saturated or unsaturated, or even aromatic acids, comprising 6 to 54, 30 notably 6 to 40, carbon atoms, and even better 6 to 24 carbon atoms. Among the acids including at least 3 carboxylic acid functions, mention may preferably be made of: 41 - tricarboxylic acids such as cyclohexanetricarboxylic acid, trimellitic acid, 1,2,3- benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid; citric acid, tetracarboxylic acids such as butanetetracarboxylic acid, pyromellitic acid and mixtures thereof. Preferably, the acid including at least 3 carboxylic acid functions is citric acid. 5 According to another embodiment, the alkyd resin(s) (A) are obtained by polycondensation of: - 0% to 12% by mass of at least one diol; - 20% to 50% by mass of at least one compound including at least 3 alcohol functions; - 10% to 30% by mass of at least one dicarboxylic acid compound; 10 - 0% to 17% by mass, preferably 0% by mass, of at least one compound including at least 3 carboxylic acid functions; - 0% to 10% by mass, preferably 0% by mass, of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty monoacid; 15 the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to yet another embodiment, the alkyd resin(s) (A) are obtained by polycondensation of: - 10% to 30% by mass of at least one diol; - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; 20 - 0% to 12% by mass of at least one dicarboxylic acid compound; - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 20% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass, preferably 40% to 59% by mass, more preferentially 45% to 55% by 25 mass, of at least one fatty alcohol, at least one of which contains at least one ethylenic unsaturation, preferably a single fatty alcohol, more preferentially oleyl alcohol. the mass percentages being expressed relative to the total weight of the alkyd resin (A). According to one embodiment, the alkyd resin(s) (A) are obtained without using a compound including at least three carboxylic acid functions. 30 Particular polyesters 42 Various processes for preparing polycondensates have been described, notably by Witzeman et al. in the Journal of Coatings Technology, Vol.62, No.789, pages 101-112 (1990) or else in Self-Healable Covalently Adaptable Networks Based on Disulfide Exchange, Polymers 2022, 14, 3953. 5 According to the invention, a polyester of formula (I) may be prepared easily in a single synthesis step from alkyd resins (A), which are themselves obtained via a polycondensation reaction. According to one of its aspects, the present invention relates to a polyester of formula (I) below, comprising at least two acetoacetate functions, and also the optical or geometrical 10 isomers thereof, and / or the solvates thereof, such as hydrates, or a composition containing same: (Z)–[O-C(O)-C(Ra)(Rb)-C(O)-R4]u (I) in which formula (I): - u is an integer greater than 2; 15 - R4represents a linear or branched, saturated or unsaturated C1-C6monovalent hydrocarbon- based radical, preferably a (C1-C4)alkyl group, in particular methyl or tert-butyl, more preferentially methyl; - Raand Rb, which may be identical or different, represent a hydrogen atom or a (C1-C4)alkyl group, preferably a hydrogen atom; and 20 - Z denotes a multivalent radical derived: I) from an alkyd resin (A1) obtained by polycondensation of: -10% to 62% by mass, preferably 10% to 42% by mass, of at least one polyol; - 10% to 62% by mass, preferably 10% to 42% by mass, of at least one polyacid; and - 35% to 60% by mass of at least one fatty alcohol, at least one of which contains at least 25 one ethylenic unsaturation; relative to the total weight of the alkyd resin (A1); or II) from an alkyd resin (A2) obtained by polycondensation of: -10% to 62% by mass of at least one polyol, said at least one polyol being or comprising at 30 least dipentaerythritol; - 10% to 62% by mass of at least one polyacid; and - 35% to 60% by mass of at least one fatty monoacid; 43 relative to the total weight of the alkyd resin (A2); or III) from an alkyd resin (A3) obtained by polycondensation of: -10% to 62% by mass of at least one polyol, said at least one polyol being xylitol or 5 comprising at least xylitol; - 10% to 62% by mass of at least one polyacid; and - 35% to 60% by mass of at least one fatty monoacid; relative to the total weight of the alkyd resin (A3); or: 10 IV) from an alkyd resin (A4) obtained by polycondensation of: -10% to 62% by mass of a mixture of at least two polyols, said mixture not containing any dipentaerythritol or any xylitol; - 10% to 62% by mass of at least one polyacid; and - 35% to 60% by mass of at least one fatty monoacid; 15 relative to the total weight of the alkyd resin (A4); or V) from an alkyd resin (A5) obtained by polycondensation of: -10% to 62% by mass of at least one polyol other than pentaerythritol and xylitol; - 10% to 62% by mass of at least one polyacid; and 20 - 35% to 60% by mass of a mixture of at least two fatty monoacids; relative to the total weight of the alkyd resin (A5); or VI) from an alkyd resin (A6) obtained by polycondensation of: -10% to 62% by mass of a polyol other than dipentaerythritol and xylitol; 25 - 10% to 62% by mass of at least one polyacid; and - 35% to 60% by mass of a fatty monoacid other than oleic acid; relative to the total weight of the alkyd resin (A6); or VII) from an alkyd resin (A7) obtained by polycondensation of: 30 - 10% to 62% by mass, preferably 10% to 42% by mass, of at least one polyol; - 10% to 62% by mass, preferably 10% to 42% by mass, of at least one polyacid, at least one of which contains at least one ethylenic unsaturation; and 44 - 35% to 60% by mass of at least one saturated fatty alcohol; relative to the total weight of the alkyd resin (A7). Preferably, the polyesters P1 are obtained from alkyd resins (A1) which are themselves obtained by a one-step polycondensation of: 5 - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; - 10% to 30% by mass of at least one diol; - 0% to 12% by mass of at least one dicarboxylic acid compound; - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid functions; 10 - 0% to 20% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty alcohol, at least one of which contains at least one ethylenic unsaturation; relative to the total weight of the alkyd resin (A1). More preferentially, the polyesters P1 are obtained from alkyd resins (A1) which are 15 themselves obtained by a one-step polycondensation of: - 10% to 30% by mass, preferably 15% to 27% by mass, more preferentially 20% to 25% by mass, of at least one diol, said at least one diol being or comprising at least 1,10-decanediol; - 20% to 50% by mass, preferably 21% to 40% by mass, more preferentially 21% to 30% by mass of at least one compound including at least 3 carboxylic acid functions, said at least 20 one compound including at least 3 carboxylic acid functions being or comprising at least citric acid; - 35% to 60% by mass of at least one fatty alcohol, said at least one fatty alcohol being or comprising at least oleyl alcohol, more preferentially being oleyl alcohol. Even more preferentially, polyester P1 is the one obtained in Example 6.3. 25 Preferably, the polyesters P2 are obtained from alkyd resins (A2) which are themselves obtained by a one-step polycondensation of: - 10% to 62% by mass, preferably 10% to 50% by mass, of at least one polyol, said polyol being or comprising at least dipentaerythritol; - 10% to 62% by mass, preferably 10% to 50% by mass, more preferentially 10% to 30% by 30 mass, of at least one dicarboxylic acid compound and / or compound including at least 3 carboxylic acid functions, preferably at least one dicarboxylic acid compound; - 35% to 60% by mass of at least one fatty monoacid; 45 relative to the total weight of the alkyd resin (A2). More preferentially, the polyesters P2 are obtained from alkyd resins (A2) which are themselves obtained by a one-step polycondensation of: - 0% to 12% by mass, preferably 0% to 10% by mass, more preferentially 0% to 8% by mass 5 of at least one diol, preferably a single diol, more preferentially Pripol 2033; - 20% to 50% by mass, preferably 25% to 50%, of at least one compound including at least 3 alcohol functions, said at least one compound including at least 3 alcohol functions being or comprising at least dipentaerythritol; preferably, said at least one compound including at least 3 alcohol functions being dipentaerythritol or a mixture of dipentaerythritol and 10 erythritol; - 10% to 30% by mass of at least one dicarboxylic acid compound, preferably a mixture of dicarboxylic acid compounds, more preferentially a mixture of adipic acid and homophthalic acid; - 0% to 17% by mass, preferably 0% by mass, of at least one compound including at least 3 15 carboxylic acid functions; - 0% to 10% by mass, preferably 0% by mass, of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty monoacid, preferably chosen from octanoic acid, oleic acid, lauric acid, isostearic acid, more preferentially a mixture of lauric acid and 20 isostearic acid or a mixture of octanoic acid and oleic acid, relative to the total weight of the alkyd resin (A2). Even more preferentially, the polyesters P2 are those obtained in Examples 4.2 and 5.2. Preferably, the polyesters P3 are obtained from alkyd resins (A3) which are themselves obtained by a one-step polycondensation of: 25 - 10% to 50% by mass of at least one compound including at least 3 alcohol functions, said at least one compound including at least 3 alcohol functions being or comprising at least xylitol; and - 10% to 30% by mass of at least one dicarboxylic acid compound; and - 35% to 60% by mass of at least one fatty monoacid; 30 relative to the total weight of the alkyd resin (A3). More preferentially, the polyesters P3 are obtained from alkyd resins (A3) which are themselves obtained by a one-step polycondensation of: 46 - 0% to 12% by mass, preferably 0% by mass, of at least one diol; - 20% to 50% by mass of at least one compound including at least 3 alcohol functions, said at least one compound including at least 3 alcohol functions being or comprising at least xylitol; preferably, said at least one compound including at least 3 alcohol functions being 5 xylitol; - 10% to 30% by mass of at least one dicarboxylic acid compound, preferably a single dicarboxylic acid compound, more preferentially sebacic acid; - 0% to 17% by mass, preferably 0% by mass, of at least one compound including at least 3 carboxylic acid functions; and 10 - 0% to 10% by mass, preferably 0% by mass, of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty monoacid, preferably chosen from octanoic acid, oleic acid, lauric acid, isostearic acid, more preferentially a single fatty acid, even more preferentially octanoic acid, 15 relative to the total weight of the alkyd resin (A3). Even more preferentially, the polyesters P3 are those obtained in Example 3.2. Preferably, the polyesters P4 are obtained from alkyd resins (A4) which are themselves obtained by a one-step polycondensation of: - 10% to 62% by mass of a mixture of at least two compounds each including at least 3 20 alcohol functions, said mixture not containing any dipentaerythritol or xylitol; - 10% to 30% by mass of at least one dicarboxylic acid compound; - 35% to 60% by mass of at least one fatty monoacid; relative to the total weight of the alkyd resin (A4). More preferentially, the polyesters P4 are obtained from alkyd resins (A4) which are 25 themselves obtained by a one-step polycondensation of: - 0% to 12% by mass, preferably 0% by mass, of at least one diol; - 20% to 50% by mass of a mixture of at least two compounds each including at least 3 alcohol functions, said mixture not containing any dipentaerythritol or xylitol; - 10% to 30% by mass of at least one dicarboxylic acid compound; 30 - 0% to 17% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 10% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty monoacid; 47 relative to the total weight of the alkyd resin (A4). Even more preferentially, the polyesters P4 are obtained from alkyd resins (A4) which are themselves obtained by a one-step polycondensation of: - 0% to 12% by mass, preferably 0% by mass, of at least one diol; 5 - 20% to 50% by mass of a mixture of at least two compounds chosen from glycerol, trimethylolpropane, pentaerythritol (tetramethylolmethane), erythritol, diglycerol, sorbitol and mannitol; - 10% to 30% by mass of at least one dicarboxylic acid compound; - 0% to 17% by mass of at least one compound including at least 3 carboxylic acid functions; 10 - 0% to 10% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty monoacid; relative to the total weight of the alkyd resin (A4). Preferably, the polyesters P5 are obtained from alkyd resins (A5) which are themselves obtained by a one-step polycondensation of: 15 - 10% to 50% by mass of a single compound including at least 3 alcohol functions, said compound being other than pentaerythritol and xylitol; - 10% to 30% by mass of at least one dicarboxylic acid compound; - 35% to 60% by mass of a mixture of at least two fatty monoacids; relative to the total weight of the alkyd resin (A5). 20 More preferentially, the polyesters P5 are obtained from alkyd resins (A5) which are themselves obtained by a one-step polycondensation of: - 0% to 12% by mass, preferably 0% by mass, of at least one diol; - 20% to 50% by mass of a single compound including at least 3 alcohol functions, said compound being other than dipentaerythritol and xylitol; 25 - 10% to 30% by mass of at least one dicarboxylic acid compound; - 0% to 17% by mass, preferably 0% by mass, of at least one compound including at least 3 carboxylic acid functions; - 0% to 10% by mass, preferably 0% by mass, of at least one monocarboxylic acid compound; and 30 - 35% to 60% by mass of a mixture of at least two fatty monoacids, preferably a mixture of two fatty acids, relative to the total weight of the alkyd resin (A5). 48 Even more preferentially, the polyesters P5 are obtained from alkyd resins (A5) which are themselves obtained by a one-step polycondensation of: - 0% to 12% by mass, preferably 0% by mass, of at least one diol; - 20% to 50% by mass of a single compound including at least 3 alcohol functions, said 5 compound being chosen from glycerol, pentaerythritol, erythritol, diglycerol; and more preferentially denoting pentaerythritol; - 10% to 30% by mass of at least one dicarboxylic acid compound; - 0% to 17% by mass, preferably 0% by mass, of at least one compound including at least 3 carboxylic acid functions; 10 - 0% to 10% by mass, preferably 0% by mass, of at least one monocarboxylic acid compound; and - 35% to 60% by mass of a mixture of at least two fatty monoacids, preferably a mixture of two fatty acids, relative to the total weight of the alkyd resin (A5). 15 Preferably, the polyesters P6 are obtained from alkyd resins (A6) which are themselves obtained by a one-step polycondensation of: -10% to 50% by mass of a polyol other than dipentaerythritol and xylitol; - 10% to 30% by mass of at least one dicarboxylic acid compound; and - 35% to 60% by mass of a fatty monoacid, said at least one fatty acid being other than oleic 20 acid; relative to the total weight of the alkyd resin (A6). More preferentially, the polyesters P6 are obtained from alkyd resins (A6) which are themselves obtained by a one-step polycondensation of: - 0% to 12% by mass, preferably 0% by mass, of at least one diol; 25 - 20% to 50% by mass of a compound including at least 3 alcohol functions other than dipentaerythritol and xylitol; - 10% to 30% by mass of at least one dicarboxylic acid compound; - 0% to 17% by mass, preferably 0% by mass, of at least one compound including at least 3 carboxylic acid functions; 30 - 0% to 10% by mass, preferably 0% by mass, of at least one monocarboxylic acid compound; and - 35% to 60% by mass of a fatty monoacid other than oleic acid; 49 relative to the total weight of the alkyd resin (A6). Even more preferentially, the polyesters P6 are obtained from alkyd resins (A6) which are themselves obtained by a one-step polycondensation of: - 20% to 50% by mass of a compound including at least 3 alcohol functions chosen from 5 triols and tetraols, preferably chosen from glycerol, pentaerythritol, erythritol and diglycerol; and more preferentially chosen from pentaerythritol; - 10% to 30% by mass of at least one dicarboxylic acid compound, preferably chosen from sebacic acid, homophthalic acid, Pripol 1009, malonic acid, succinic acid and itaconic acid, more preferentially chosen from sebacic acid, homophthalic acid, and mixtures thereof, even 10 more preferentially a single dicarboxylic acid compound chosen from sebacic acid and homophthalic acid; - 35% to 60% by mass of a fatty monoacid chosen from isostearic acid, octanoic acid, lauric acid, palmitic acid and myristoleic acid, more preferentially chosen from isostearic acid, relative to the total weight of the alkyd resin (A6). 15 Better still, the polyesters P6 are those obtained in Examples 1.2 and 2.2. Preferably, the polyesters P7 are obtained from alkyd resins (A7) which are themselves obtained by a one-step polycondensation of: - 10% to 30% by mass of at least one diol; - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; 20 - 0% to 12% by mass of at least one dicarboxylic acid compound; - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid functions; - 0% to 20% by mass of at least one monocarboxylic acid compound; and - 35% to 60% by mass of at least one fatty alcohol, at least one of which contains at least 25 one ethylenic unsaturation; relative to the total weight of the alkyd resin (A7). More preferentially, the polyesters P7 are obtained from alkyd resins (A7) which are themselves obtained by a one-step polycondensation of: - 10% to 30% by mass, preferably 15% to 27% by mass, more preferentially 20% to 25% by 30 mass, of at least one diol, said at least one diol being or comprising at least 1,10-decanediol; - 20% to 50% by mass, preferably 21% to 40% by mass, more preferentially 21% to 30% by mass of at least one compound including at least 3 carboxylic acid functions, said at least 50 one compound including at least 3 carboxylic acid functions being or comprising at least citric acid; and - 35% to 60% by mass of at least one fatty alcohol, said at least one fatty alcohol being or comprising at least oleyl alcohol, more preferentially being oleyl alcohol. 5 Alkyd resins (B) The alkyd resins (B) used in the preparation of the polyesters of formula (I) may be prepared in two successive steps, the first step leading to alkyd resins (A) containing ethylenic unsaturations. 10 Thus, the alkyd resins (B) may be obtained in one step from alkyd resins (A) containing ethylenic unsaturations. In particular, an alkyd resin (B) used in the preparation of the polyesters of formula (I) is characterized in that it is derived from the reaction of an alkyd resin (A) containing ethylenic unsaturations with at least one (poly)hydroxy thiol, said alkyd resin (A) being obtained via: 15 a) a first step by polycondensation of: - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; - 10% to 30% by mass of at least one diol; - 0% to 12% by mass of at least one dicarboxylic acid compound; - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid 20 functions; - 35% to 60% by mass of at least one fatty alcohol; and - 0% to 20% by mass of at least one monocarboxylic acid compound, the mass percentages being expressed relative to the total weight of the alkyd resin (A), it being understood that at least one of the dicarboxylic acid compounds and compounds 25 containing at least 3 carboxylic acid functions, and / or at least one of the fatty alcohols, contains at least one ethylenic unsaturation; followed by b) a second step consisting of a thiol-ene reaction of all or part of the ethylenic unsaturations of the alkyd resin (A) obtained on conclusion of step a), with at least one (poly)hydroxy thiol, preferably of formula (F1) below: 30 RD-SH (F1) in which RD represents a linear or branched C2-C10hydrocarbon-based radical substituted with at least one hydroxyl radical, preferably substituted with one or two hydroxyl radicals. 51 Preferably, the alkyd resin(s) (A) containing ethylenic unsaturations obtained on conclusion of step a) have a hydroxyl number of less than 50 mg KOH / g. According to a preferred embodiment, the alkyd resin(s) (A) containing ethylenic unsaturations are obtained by a one-step polycondensation a) of: 5 - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; - 10% to 30% by mass of at least one diol; - 0% to 12% by mass of at least one dicarboxylic acid compound, which is preferably saturated; - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid 10 functions, which is preferably saturated; - 35% to 60% by mass of at least one fatty alcohol; and - 0% to 20% by mass of at least one monocarboxylic acid compound, the mass percentages being expressed relative to the total weight of the alkyd resin (A), it being understood that at least one of the fatty alcohols contains at least one ethylenic 15 unsaturation. According to this embodiment, preferably, the dicarboxylic acid compounds and the compounds including at least 3 carboxylic acid functions are saturated. Still according to this embodiment, preferably, the acid number of the alkyd resin (A) obtained on conclusion of step a) is between 0 and 15 mg KOH / g. 20 Preferably, the fatty alcohol(s) comprising at least one ethylenic unsaturation used in step a) are chosen from 9-decen-1-ol, citronellol, oleyl alcohol, linoleyl alcohol and mixtures thereof, more preferentially oleyl alcohol. The (poly)hydroxy thiol(s) used during step b) may be chosen from 2-mercaptoethanol, 3- mercapto-1-propanol, 6-mercapto-1-hexanol, 4-mercapto-1-butanol, 3-mercapto-3- 25 methylbutanol, 3-mercapto-2-butanol and 3-mercapto-1,2-propanediol. Preferably, only one (poly)hydroxy thiol is used during step b); more preferentially, the (poly)hydroxy thiol is 3-mercapto-1,2-propanediol. On conclusion of step b), an alkyd resin (B) bearing hydroxyl groups is obtained, and preferably the hydroxyl number of (B) is greater than 50 mg KOH / g of alkyd resin (B), more 30 preferentially greater than 100 mg KOH / g of alkyd resin (B). PREPARATION PROCESS 52 In general, the polyesters bearing radicals -C(O)-C(Ra)(Rb)-C(O)-R4according to the invention are prepared in one step from alkyd resin (A) or alkyd resin (B) as described previously by reacting all or some of the hydroxyl functions of the alkyd resin (A) or (B), for example via a (trans)esterification reaction with an ester Gp-C(O)-C(Ra)(Rb)-C(O)-R4, 5 in which Gp denotes a leaving group which is preferably a hydroxyl radical or a (C1- C4)alkoxy radical, such as methoxy, ethoxy, isobutoxy or t-butoxy, to form esters -O-C(O)- C(Ra)(Rb)-C(O)-R4with Ra, Rband R4as defined previously. Preferably, Raand Rbare identical and denote a hydrogen atom. Preferably, R4 denotes a methyl radical. 10 According to a preferred embodiment, Gp-C(O)-C(Ra)(Rb)-C(O)-R4denotes an ester chosen from ethyl acetoacetate, ethyl 2-methylacetoacetate and tert-butyl acetoacetate, preferably tert-butyl acetoacetate. According to a preferred embodiment, at least 20% of the hydroxyl radicals of the alkyd resin (A) or (B) are converted into esters -O-C(O)-C(Ra)(Rb)-C(O)-R4, preferably at least 15 30%, more preferentially at least 40%, even more preferentially at least 50%, better still at least 80%. According to a preferred embodiment, the hydroxyl number of the polyesters according to the invention is less than 50 mg KOH / g polyester. 20 According to another of its aspects, the invention relates to a process for preparing polyester compounds of formula (I) comprising at least two acetoacetate functions as described previously, comprising at least one step of reacting all or some of the hydroxyl functions of at least one alkyd resin (A1), (A2), (A3), (A4), (A5), (A6) or (A7), preferably via a (trans)esterification reaction with an ester Gp-C(O)-C(Ra)(Rb)-C(O)-R4, in which Gp 25 denotes a leaving group, preferably a hydroxyl radical or a (C1-C4)alkoxy radical, such as methoxy, ethoxy, isobutoxy or t-butoxy, to form esters -O-C(O)-C(Ra)(Rb)-C(O)-R4 with Ra, Rband R4being as defined above. In particular, the polyesters of Examples 1.2, 2.2, 3.2, 4.2 and 5.2 are obtained in one step from the alkyd resins (A). 30 Preferably, the polyesters derived from alkyd resins (A1) are prepared in two steps, the first step being the thiolene reaction of all or some of the ethylenic unsaturations of the alkyd resin (A1) with at least one (poly)hydroxy thiol as described previously to give a resin (B1), 53 the second step being the reaction of all or some of the hydroxyl functions of the alkyd resin (A) or (B), for example via a (trans)esterification reaction with an ester Gp-C(O)-C(Ra)(Rb)- C(O)-R4. More preferentially, the polyester of Example 6.3 is obtained according to this two-step 5 process. CROSSLINKING AGENT According to a particular embodiment, the treatment process according to the invention as described previously comprises the application to keratin fibers, preferably the hair, of (i) at 10 least one polyester of formula (I) as defined previously, and (ii) at least one crosslinking agent. For the purposes of the invention, the term “crosslinking agent”, also termed “R”, denotes a compound that is capable of establishing with at least one acetoacetate function of the polyester(s) of formula (I) used in the treatment process according to the invention: 15 - at least one covalent bond, - at least one donor-acceptor (dative) bond, and / or - at least one coordination bond, and thus of crosslinking this or these compounds. Preferably, the term “crosslinking agent”, also termed “R”, refers to a compound that is 20 capable of establishing at least one covalent bond with an acetoacetate function of the polyester(s) of formula (I) used in the treatment process according to the invention and thus of crosslinking this or these compounds. For the purposes of the present invention, it is understood that the terms “crosslinking agent” and “crosslinker” are equivalent. 25 Compositions “C2”, “C3” and “C4” as defined previously contain at least ii) a crosslinking agent. The compositions of the invention may comprise a fatty phase, an aqueous phase or may be in the form of a direct or inverse emulsion. Composition “C4” may be an aqueous composition. According to one aspect, the treatment process of the invention uses a composition termed 30 “C3”, in particular a cosmetic composition for treating keratin fibers, in particular for caring for, styling and / or coloring keratin fibers, preferably the hair, i) at least one polyester of formula (I), as defined previously and hereinbelow, ii) at least one crosslinking agent, in 54 particular as defined previously and hereinbelow, and iv) at least one cosmetic active agent, in particular as defined previously and hereinbelow. The crosslinking agent(s) ii) are preferably present in a mass content ranging from 0.2% to 60% by weight, in particular ranging from 0.5% to 40% by weight, more particularly from 5 1% to 35% by weight, even more particularly from 1% to 30% relative to the total weight of the composition containing same. In particular, in composition “C2” or “C3”, the crosslinking agent(s) ii) and the polyester(s) i) as defined previously are preferably present in a mass content ranging from 1% to 35% by weight, relative to the total weight of the composition comprising them. 10 When the treatment process includes several steps including a step of using one or more polyesters of formula (I) without a crosslinking agent, the polyester(s) of formula (I) may be used alone (pure), or in a composition “C1” as described previously. More precisely, the crosslinking agent(s) ii) that are suitable for use in the invention may be chosen from compounds bearing amine, thiol, acrylate and / or carbonyl functions such as a 15 ketone or aldehyde function, or mixtures thereof. A crosslinking agent R may also denote a metal alkoxide. According to a particular embodiment, the crosslinking agent(s) do not contain any metal salts. Thus, according to a particular embodiment, the crosslinking agent(s) ii) are chosen from A) (poly)amine compounds, B) polythiol compounds, C) polyacrylates, D) metal alkoxides, E) 20 polycarbonyl compounds, and mixtures thereof, preferably chosen from A) polyamine compounds, B) polythiol compounds, E) metal alkoxides, and mixtures thereof. The terms “polyamine compounds,” “polythiol compounds,” “polycarbonyl compounds,” and “polyacrylate compounds” refer to compounds including at least two primary or secondary amine, thiol, carbonyl (such as a ketone or aldehyde) or acrylate functions, 25 respectively. The metal alkoxide compounds are defined hereinbelow. According to one embodiment, the process according to the invention uses a single crosslinking agent. According to another embodiment, the process according to the invention uses several 30 crosslinking agents exclusively from the same family, namely several crosslinking agents A) without crosslinking agent B), C), D) E), or several crosslinking agents B) without crosslinking agent A), C), D), E), or several crosslinking agents C) without crosslinking 55 agent A), B), D), E), or several crosslinking agents D) without crosslinking agent A), B), C), E), or several crosslinking agents E) without crosslinking agent A), B), C), D). According to yet another embodiment, the method according to the invention uses at least two crosslinking agents belonging to different families, for instance at least one crosslinking 5 agent A) with at least one crosslinking agent B) and / or C) and / or D) and / or E), or at least one crosslinking agent B) with at least one crosslinking agent A), C), D), E), or at least one crosslinking agent C) with at least one crosslinking agent A), B), D), E), or at least one crosslinking agent D) with at least one crosslinking agent A), B), C), E), or at least one crosslinking agent E) with at least one crosslinking agent A), B), C), D). 10 According to a preferred embodiment, the process according to the invention comprises the application of at least one crosslinking agent R chosen from (poly)amine compounds. The (poly)amine compound is in particular chosen from polyamine compounds containing 15 several primary amine and / or secondary amine groups or from amino alkoxysilanes containing only a single primary and / or secondary amine group, and more particularly from amino alkoxysilane compounds including only one primary and / or secondary amine group, diamine compounds, triamine compounds, and mixtures thereof. The (poly)amine compound may be a compound comprising from 2 to 20 carbon atoms, 20 notably a non-polymeric compound; they may be acyclic or cyclic, linear or branched, saturated or unsaturated, conjugated or non-conjugated, aromatic or non-aromatic, optionally interrupted with one or more heteroatoms or groups chosen from -O-, -S-, - Si(R’)2- and -N(R’’)-, preferably -O-, -Si(R’)2-, or combinations thereof such as -Si(R’)2-O- or -O-Si(R’)2-, with R’, which may be identical or different, representing a (C1-C4)alkyl 25 group such as methyl, and R’’ representing a hydrogen atom or a (C1-C4)alkyl group, preferably a hydrogen atom. The term “non-polymeric compound” means a compound which is not directly obtained via a monomer polymerization reaction. (Poly)amine compounds that may be mentioned in particular include N-methyl-1,3-30 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- 56 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, 1,3- 5 bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, diaminopropanol, 4,7,10-trioxa-1,13-tridecanediamine, spermidine and C36-alkylenediamines (PriamineTM1071, 1073, 1074, 1075, respectively), preferably spermidine and / or 4,7,10-trioxa-1,13- tridecanediamine. According to a particular embodiment of the invention, the (poly)amine compound(s) are 10 monoamine compounds, i.e. they contain only one primary and / or secondary amine group, preferably a primary amine group (NH2). The (poly)amine compound(s) may be chosen from amino alkoxysilanes, notably of formula R’1Si(OR’2)z(R’3)x in which: - R’1is a linear or branched, saturated or unsaturated, cyclic or acyclic C1-C615 hydrocarbon-based chain substituted with a group chosen from primary amine groups NH2or secondary amine groups -N(H)R with R representing a C1-C4 alkyl, an aryl or a benzyl substituted with an amino group or with a C1-C4aminoalkyl group; R’1may be interrupted in its chain with a heteroatom (O, S, NH) or a carbonyl group (CO), R’1being linked to the silicon atom directly via a carbon atom, 20 - R’2and R’3, which may be identical or different, represent a linear or branched (C1- C6)alkyl group, - z denotes an integer ranging from 1 to 3, and - x denotes an integer ranging from 0 to 2, with z + x = 3. 25 In particular, R’1 is an acyclic chain. Preferably, R’1 is a linear or branched, saturated or unsaturated C1-C6 hydrocarbon-based chain substituted with an amine -NH2 or -N(H)R group, with R representing a C1-C6alkyl, a C3-C6cycloalkyl or a C6aromatic group. More preferentially, R’1is a saturated linear C1-C6hydrocarbon-based chain substituted with an amine group NH2. Even more preferentially, R’1 is a saturated linear C2-C4 hydrocarbon- 30 based chain substituted with an amine group NH2. 57 In particular, R’2represents an alkyl group comprising from 1 to 4 carbon atoms; preferably, 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’3represents an alkyl group comprising from 1 to 4 carbon atoms; preferably, 5 R’3represents a linear alkyl group comprising from 1 to 4 carbon atoms and more preferentially R’3 represents methyl or ethyl groups. Preferably, z is equal to 3. In particular, the (poly)amine compound(s) are chosen from amino alkoxysilanes including only one primary and / or secondary, preferably primary (NH2), amine group, such as 3- aminopropyltriethoxysilane (APTES), 3-aminoethyltriethoxysilane (AETES), 3-10 aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-(m- aminophenoxy)propyltrimethoxysilane, p-aminophenyltrimethoxysilane, and N-(2- aminoethylaminomethyl)phenethyltrimethoxysilane. Preferably, the (poly)amine compound(s) are chosen from 3-aminopropyltriethoxysilane (APTES), 3-aminoethyltriethoxysilane (AETES), 3-aminopropylmethyldiethoxysilane, and15 N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and more preferentially 3- aminopropyltriethoxysilane (APTES), in particular the product sold by Sigma-Aldrich. According to a particular embodiment of the invention, the (poly)amine compounds are diamine compounds, i.e. they contain two primary and / or secondary amine groups, preferably primary amine groups (NH2). 20 More particularly, they are chosen from the compounds of formula (V) or (VI): ● ALK[(O-ALK’)m-NH2]2(V) or ● H2N-ALK-Si(R’)2-[O-Si(R’)2]m-O-Si(R)2-ALK’-NH2 (VI) in which formulae (V) and (VI): 25 - ALK and ALK’, which may be identical or different, represent a linear or branched (C1- C6)alkylene group, preferably a linear group such as propylene, - R’, which may be identical or different, represents a (C1-C4)alkyl group such as methyl, - m represents an integer greater than or equal to 0; preferably, the value of m is such that the weight-average molecular weight of compound (V) or (VI) ranges from 500 g.mol-1to 30 55000 g.mol-1. 58 As examples of compounds of formula (VI), mention may be made of those sold under the names DMS-A11, DMS-A12, DMS-A15, DMS-A21, DMS-A31, DMS-A32 and DMS-A35 by the company Gelest. The (poly)amine compound(s) that are diamines are particularly polyether diamines notably 5 of formula H2N-ALK-O-[ALK’-O]m-ALK’’-NH2with ALK, ALK’ and ALK’’, which may be identical or different, representing a linear or branched (C1-C6))alkylene group, and m representing an integer greater than or equal to 0, such as 4,7,10-trioxa-1,13- tridecanediamine or the compounds known under the reference Jeffamine from the company Hunstman, and more particularly α,ω-diamino polyethylene glycol and / or polypropylene 10 glycol (with an amine function at the end of the chain) such as the products sold under the names Jeffamine D-230, D-400, D-2000, D-4000, ED-600, ED-9000 and ED-2003. According to a particular embodiment of the invention, the (poly)amine compound(s) are triamine compounds, i.e. they contain three primary and / or secondary amine groups, preferably primary amine groups (NH2). More particularly, they are chosen from polyether 15 triamines notably of formula ALK’’’[(O-ALK’)m-NH2]3with ALK’ as defined previously and ALK’’’ representing a linear or branched trivalent (C1-C6)alkylene group, and m representing an integer greater than or equal to 0. As (poly)amine compounds that are triamine compounds, mention may be made in particular of polyether triamines, and notably α,ω-diamino polyethylene glycol and / or polypropylene 20 glycol (with an amine function at the end of the chain) such as the products sold under the names Jeffamine T-403. According to another particular embodiment of the invention, the (poly)amine compound(s) include more than three primary and / or secondary amine groups, preferably primary amine groups (NH2). 25 In this variant, the (poly)amine compound(s) are chosen from poly(meth)acrylates or poly(meth)acrylamides bearing lateral primary or secondary amine functions, such as poly(3-aminopropyl)methacrylamide and poly(2-aminoethyl) methacrylate. Preferably, the (poly)amine compounds are chosen from chitosans (notably poly(D- glucosamine)) and polydimethylsiloxanes comprising primary amine groups at the end of 30 the chain and / or on side chains. According to this variant, the (poly)amine compound(s) are chosen in particular from poly((C2-C5)alkyleneimines), and preferably polyethyleneimines and polypropyleneimines, 59 notably poly(ethyleneimines), in particular the product sold under reference 408700 by the company Aldrich Chemical or under the trade name Lupasol by BASF, notably with a molecular weight of between 1200 and 25000; poly(allylamine), in particular the product sold under reference 479136 by the company Aldrich Chemical; polyvinylamines and 5 copolymers thereof, notably with vinylamides, in particular vinylamine / vinylformamide copolymers such as those sold under the name Lupamin®9030 by the company BASF; polyamine acids containing NH2groups, such as polylysine, in particular the product sold by the company JNC Corporation (formerly Chisso); amino dextran, in particular the product sold by the company CarboMer Inc; amino polyvinyl alcohol, in particular the product sold 10 by the company CarboMer Inc; acrylamido(C1-C6)alkylamine-based copolymers, notably acrylamidopropylamine-based copolymers; and poly(D-glucosamine), for example sold under the reference Kionutrime CSG®by the company Kytozyme. According to a particular embodiment, the polydimethylsiloxanes comprising primary amine groups at the end of the chain and / or on side chains are chosen from the compounds of 15 formula (VII) below: Ra-Si(Rb)(Rc)-O-[Si(Rb)(Rc)-O]m-[Si(ALK1-NH2)(Ra)-O]n-Si(Rb)(Rc)-Ra (VII) in which formula (VII): - Ra, which may be identical or different, represents a hydroxyl or (C1-C4)alkyl group, - Rb and Rc, which may be identical or different, preferably identical, represent a (C1-C4)alkyl 20 group, such as methyl, - ALK1represents a linear or branched (C1-C6) alkylene group, optionally interrupted with an N(H) group, - m and n are integers greater than or equal to 1; preferably, m and n are such that the weight- average molecular mass of the compound of formula (VII) ranges from 1000 g.mol-1to 25 500000 g.mol-1. According to a preferred variant, formula (VII) is such that Ra, Rb and Rc represent a methyl group, ALK1represents a propylene group, n and m are such that the weight-average molecular weight of the polydimethylsiloxane ranges from 1000 g.mol1to 55000 g.mol1. As examples of polydimethylsiloxanes of formula (VI), mention may be made of those sold 30 under the names AMS-132, AMS-152, AMS-162, AMS-163, AMS-191 and AMS-1203 by the company Gelest. 60 According to another variant, formula (VII) is such that Rarepresents a hydroxyl or (C1- C4)alkyl group, such as methyl, ALK1represents a (C5-C6)alkylene group substituted with an NH group; preferably, ALK1represents -(CH2)3-N(H)-(CH2)2-, and m and n are such that the weight-average molecular mass of the compound of formula (VI) ranges from 5 5000 g.mol-1to 500000 g.mol-1. As amine polymer, mention may also be made of α,ω-diamino polytetrahydrofurans (or polytetramethylene glycol) and α,ω-diamino polybutadienes. According to a particular embodiment of the invention, the (poly)amine compounds are chosen from hyperbranched polymers comprising at least one amino group and dendrimers 10 bearing at least one amino group, such as PAMAM polyamidoamine dendrimers with an ethylenediamine core and a terminal amine function. According to a preferred embodiment, the composition comprises a crosslinking agent R chosen from (poly)amine compounds, in particular chosen from chitosans, aminoalkoxysilanes, polydimethylsiloxanes comprising primary amine groups at the end of 15 the chain or on side chains, amodimethicones, polyglucosamines, spermidine and mixtures thereof. More preferentially, the composition comprises a crosslinking agent R chosen from spermidine, chitosans, aminoalkoxysilanes and polydialkylsiloxanes comprising primary amine groups at the end of the chain or on side chains such as amodimethicones, and even 20 more preferentially chosen from poly(D-glucosamine), 3-aminopropyltriethoxysilane (APTES), 3-aminoethyltriethoxysilane (AETES), 3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl)-3-aminopropyltriethoxysilane, spermidine and polydimethylsiloxanes comprising terminal amino groups at the end of the chain, such as bis-cetearyl amodimethicone. 25 According to a preferred embodiment, the process according to the invention comprises the application of at least one crosslinking agent R chosen from (poly)thiol compounds also known as (poly)mercapto compounds. 30 The (poly)thiol compound may in particular be organic or inorganic, preferably organic. In a preferred embodiment, the (poly)thiol compound is silicon-based, i.e. it includes one or more thiol groups and it also includes at least one siloxane chain. 61 In a particular embodiment, the (poly)thiol compound is inorganic. Mention may be made, for example, of polythiol silicones. The (poly)thiol compound may in particular be chosen from non-polymeric (poly)thiol compounds. 5 For the purposes of the present invention, the term “non-polymeric compounds” means compounds which are not directly obtained via a monomer polymerization reaction. According to one embodiment of the invention, the (poly)thiol compound(s) are organic, non-polymeric and of formula (VIII) below and also the solvates thereof such as hydrates: L(SH)q (VIII) 10 in which formula (VIII): - q denotes an integer greater than or equal to 2; preferably, q is between 2 and 10 and preferably between 2 and 5 inclusive; - L denotes a linear or branched, saturated or unsaturated, or (hetero)cyclic, saturated or unsaturated, multivalent (at least divalent) group, in particular comprising between 1 and 15 500 carbon and / or silicon atoms, more particularly between 2 and 40 carbon and / or silicon atoms, even more particularly between 3 and 30 carbon and / or silicon atoms, preferably between 6 and 20 carbon atoms; L being optionally interrupted and / or terminated with one or more heteroatoms or groups chosen from O, S, N, Si, C(X), and combinations thereof such as -O-, -O-C(X)-, -N(R)-C(X)-, -Si(Rc)(Rd)-O- with R representing a hydrogen atom or 20 a (C1-C6)alkyl group such as methyl; and / or L being optionally substituted with one or more groups chosen from: -N(Ra)Rband -(X’)a-C(X)-(X’’)b-Ra; with X, X’ and X’’, which may be identical or different, representing an oxygen or sulfur atom, or a group N(Rb); a and b being 0 or 1, preferably the sum of a + b being 1; Ra and Rb, which may be identical or different, represent a hydrogen atom or a (C1-C6)alkyl or aryl(C1-C4)alkyl group, such as 25 benzyl, preferably Ra and Rb represent a hydrogen atom; and Rc and Rd, which may be identical or different, represent a (C1-C6)alkyl, aryl(C1-C4)alkyl or (C1-C6)alkoxy group. According to a particular embodiment of the invention, the (poly)thiol compound(s) are chosen from polythiol compounds, notably polythiol compounds comprising from 2 to 20 carbon atoms. 30 According to a preferred embodiment, the (poly)thiol compound(s) are non-polymeric and notably of formula (VIII) defined above, in which q is an integer greater than or equal to 2, preferably q is an integer between 2 and 10 and preferably between 2 and 5 inclusive. 62 The (poly)thiol compound(s) that are suitable for use in the invention are preferably dithiol compounds. Preferably, L denotes a C8-C18 multivalent radical, which is notably linear. Preferentially, the liposoluble polythiol is a notably linear C8-C18dithiol. Preferably, the C8-C18chain is a 5 hydrocarbon-based chain, i.e. formed from carbon and hydrogen. In particular, the liposoluble polythiol is a linear C8-C16 and notably C10-C14 dithiol. As (poly)thiol compounds of formula (VII), mention may be made more particularly 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- 10 dodecanedithiol and / or 1,14-tetradecanedithiol, preferentially1,12-dodecanedithiol. According to another particular embodiment of the invention, the (poly)thiol compound(s) are chosen from thiolated alkoxysiloxanes, such as those of formula (VIII’) below: R’1-Si(OR’2)z(R’3)x (VIII’) in which formula (VIII’): 15 - R’1is a linear or branched, saturated or unsaturated, cyclic or acyclic C1-C12hydrocarbon- based chain substituted with one or more groups chosen from thiol groups; and aryl, aryloxy, arylthio, arylamino, the aryl group being substituted with one or more thiol groups, or thiol(C1-C6)alkyl, preferably thiol(C1-C6)alkyl; and R’1is optionally interrupted in its hydrocarbon-based chain with one or more heteroatoms such as O, S, N, a carbonyl group 20 C(O), or a combination thereof such as ester -C(O)-O-, or amide -C(O)-N(H)-, R’1being bonded 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, preferably from 1 to 4 carbon atoms, such as methyl, - z denotes an integer ranging from 1 to 3, and 25 - x denotes an integer ranging from 0 to 2, with z + x = 3. Preferably, R’2represents a linear or branched, preferably linear, alkyl group comprising from 1 to 4 carbon atoms, such as ethyl. Preferably, R’3 represents a linear or branched, preferably linear, alkyl group comprising 30 from 1 to 4 carbon atoms, such as methyl or ethyl. 63 Preferably, R’1is an acyclic chain, in particular R’1is a linear or branched, saturated or unsaturated, preferably saturated, C1-C6 hydrocarbon-based chain substituted with one or more thiol groups, preferably substituted with one thiol group. Preferably, R’1is a saturated linear C1-C6hydrocarbon-based chain substituted with a thiol 5 group, and R’2represents an alkyl group comprising from 1 to 4 carbon atoms. Preferably, R’3 represents an alkyl group comprising from 1 to 4 carbon atoms. Preferably, z is equal to 3. According to a more particular embodiment of the invention, the thiolated alkoxysiloxanes are chosen from those of formula (IX) below: 10 (R1O)(R2)(R3)Si-[CH(R4)]t-[N(R’4)-L1]p-SH (IX) in which formula (IX): - p is 0 or 1; - t is an integer between 1 and 4, preferably 2; - R1represents a (C1-C6)alkyl radical; 15 - R2and R3, which may be identical or different, preferably identical, are chosen from a (C1- C6)alkyl group, in particular a C1-C4 alkyl group, such as methyl, and a (C1-C6)alkoxy group, in particular a (C1-C4)alkoxy group, such as methoxy; - R4and R’4, which may be identical or different, represent a hydrogen atom or a (C1-C6)alkyl group, such as methyl; 20 - L1represents a divalent, saturated, linear or branched C1-C20hydrocarbon-based radical. According to a particular embodiment of the invention, the thiolated alkoxysiloxane compounds are chosen from those of formula (IX’) below: (R’1O)(R’2)(R’3)Si-CH(R4)-CH(R5)-(L2)q-SH (IX’) in which formula (IX’): 25 - q is equal to 0 or 1; - X represents an oxygen or sulfur atom, preferably a sulfur atom; - R’1denotes a (C1-C6)alkyl radical; - R’2and R’3, which may be identical or different, preferably identical, are chosen from a (C1-C6)alkoxy group, in particular a C1-C4 alkoxy group, and a (C1-C6)alkyl radical; 30 - R5represents a hydrogen atom or a C1-C4alkyl group optionally substituted with an amino, thiol or hydroxyl group; - R4represents a hydrogen atom or a C1-C4 alkyl group, in particular methyl; 64 - L2represents a linear or branched, saturated C1-C20divalent hydrocarbon-based group, optionally interrupted with a heteroatom such as -N(H)-, and / or optionally substituted with one or more hydroxyl, thiol or amino groups. Preferably, the thiolated alkoxysilane(s) are chosen from 4-(trimethoxysilyl)-1-butanol, 3- 5 (trimethoxysilyl)-1-propanol, 3-(triethoxysilyl)-1-propanol, 11-(trimethoxysilyl)-1- undecanethiol, 4-(trimethoxysilyl)-2-butanethiol, 2-(triethoxysilyl)ethanethiol, 3- (triethoxysilyl)-1-propanethiol, 2-(trimethoxysilyl)ethanethiol, 3-(trimethoxysilyl)-1- propanethiol and 3-(dimethoxymethylsilyl)-1-propanethiol. More preferentially, the thiolated alkoxysilane(s) are chosen from 2- 10 (triethoxysilyl)ethanethiol (18236-15-2) and 3-(triethoxysilyl)-1-propanethiol (14814-09-6). According to a preferred embodiment of the invention, the (poly)thiol compound(s) are chosen from polymeric (poly)thiol compounds. The polymeric (poly)thiol compounds may be star, comb, brush and dendritic homopolymers or copolymers bearing thiol units. The polymers may be of natural origin such as 15 polysaccharides or polypeptides, or of synthetic origin such as acrylic polymers, polyesters or polyglycols. The thiol units may be present as terminal or side groups. 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; 20 EP 1247515 A2; US 3676440; and EP 1572778. The polymeric (poly)thiol compounds of the invention are preferably organic and / or silicone compounds, more preferentially of formula (X): POLY(SH)q (X) in which formula (X): 25 - q is greater than or equal to 2, preferably greater than or equal to 3; - POLY denotes a polymer-based radical, preferably carbon-based or silicone-based; POLY being optionally interrupted with one or more heteroatoms or groups chosen from O, S, N, Si, C(X), and combinations thereof such as -O-, -O-C(X)-, -N(R)-C(X)-, -Si(Rc)(Rd)-O- with R representing a hydrogen atom or a (C1-C6)alkyl group such as methyl; and / or POLY being 30 optionally substituted with one or more halogen atoms, or a group chosen from Ra(Rb)N- and -(X’)a-C(X)-(X’’)b-Ra; X, X’ and X’’, which may be identical or different, represent an oxygen or sulfur atom or a group N(Rb); a and b being 0 or 1, preferably the sum of a + b 65 being 1; Raand Rb, which may be identical or different, represent a hydrogen atom or a (C1- C10)alkyl or aryl(C1-C4)alkyl group, such as benzyl, preferably Ra and Rb represent a hydrogen atom; and Rc and Rd, which may be identical or different, represent a (C1-C10)alkyl, aryl(C1-C4)alkyl or (C1-C10)alkoxy group. 5 The methods for preparing the polymeric (poly)thiol compounds used according to the invention are known to those skilled in the art; several methods are reported hereinbelow in a non-limiting manner. The polymeric (poly)thiol compounds used according to the invention may be obtained by polymerization or polycondensation of monomer units bearing thiol or protected thiol functions, optionally as a copolymerization or co-polycondensation 10 of monomer units free of thiol or protected thiol functions. According to one embodiment of the invention, the polymeric (poly)thiol compounds used according to the invention are polymers which are soluble in cosmetic media, particularly in aqueous or aqueous-alcoholic media. They are more preferentially obtained from amino polymers and the ammonium salts thereof or from polyhydroxylated polymers. 15 According to another embodiment of the invention, the thiolated polymers used according to the invention are polymers that are soluble in lipophilic media. According to one embodiment of the invention, the polythiol compound is a polymeric compound of formula (X) in which q denotes an integer greater than or equal to 2, and POLY denotes a carbon-based and / or silicon-based, preferably silicon-based, polymeric radical, 20 POLY also possibly containing one or more heteroatoms chosen from O, N or S, and / or 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 (C1-C10)alkyl or linear or branched (C1-C10)alkoxy groups, it being understood that when POLY is substituted, the thiol functions may be borne by the substituent(s). 25 The weight-average molecular weight of the polythiol polymer compounds, such as those of formula (X), is generally between 500 and 400 000 g.mol-1, preferably between 500 and 150000 g.mol-1. According to a particular embodiment of the invention, the polythiol compounds are chosen from polyorganosiloxanes including thiol groups on end chains, such as those of formula 30 (XI) below: HS-L4-Si(Ra)(Rb)-O-[Si(Ra)(Rb)-O]n-Si(Ra)(Rb)-L5-SH (XI) in which formula (XI): 66 - Raand Rb, which may be identical or different, preferably identical, represent a group from among: (C1-C4)alkyl such as methyl, (C1-C4)alkoxy such as methoxy, aryl such as phenyl, aryloxy such as phenoxy, aryl(C1-C4)alkyl such as benzyl, or aryl(C1-C4)alkoxy such as benzoxy, preferably (C1-C4)alkyl such as methyl; 5 - 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 g.mol-1; 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 - L4and L5, which may be identical or different, preferably identical, represent a linear or 10 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, and in particular represent a covalent bond or a (C1-C6)alkylene, (C1-C6)alkylenoxy, oxy(C1-C6)alkylene, (C1-C6)alkylenoxy(C1- C6)alkylene, (C1-C6)alkylenoxy(C1-C6)alkylenoxy or oxy(C1-C6)alkylenoxy(C1-C6)alkylene15 group, preferably a (C1-C6)alkylene, (C1-C6)alkylenoxy, oxy(C1-C6)alkylene or (C1- C6)alkylenoxy(C1-C6)alkylene group. Preferentially, the (poly)thiol compounds are polythiol polyorganosiloxanes, more preferentially polythiol polydimethylsiloxanes, notably chosen from those of formula (XII): HS-L4-Si(CH3)2-O-[Si(CH3)2-O]n-Si(CH3)2-L5-SH (XII) 20 in which formula (XII): - L4and L5are as defined previously in formula (IX), in particular L4and L5represent a (C1- C6)alkylene, (C1-C6)alkylenoxy, oxy(C1-C6)alkylene or (C1-C6)alkylenoxy(C1-C6)alkylene group, more preferentially a divalent group chosen from –R2–, –O–R2–, –R2–O– and –R2– O–R2–, preferably –R2–O–R2–, with R2representing a linear or branched, preferably linear, 25 (C2-C6)alkylene group, such as ethylene or propylene, preferably propylene; and - n is as defined in formula (XI). As polythiol compounds of formula (XII), mention may be made of mercaptosiloxanes or thiolated siloxanes in which the thiol functions are at the chain ends, sold by the company Shin-Etsu under the reference X-22-167B, and mercaptosiloxanes in which the mercapto 30 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, via thio-n-propyl, 80-120 groups, sold by the company Gelest under the name DMS-SM 21. 67 Preferentially, the polythiol compounds are polyorganosiloxanes including thiol groups on side chains, such as those of formula (XIII): Ra-Si(Rb)(Rd)-O-[Si(Ra)(Rb)-O]m-[Si(Rb)(ALK1-SH)-O]n-Si(Rb)(Rd)-Ra(XIII) in which formula (XIII): 5 - Raand Rbare as defined in formula (XI) and Rdis as defined for Raand Rb, preferably Ra, Rband Rd, which are identical, represent a (C1-C6)alkyl group, such as methyl; - Rdmay also represent a (C1-C6)alkyl group substituted with a (C1-C4)alkylamino or amino or thiol group, preferably (C1-C4)alkyl such as methyl; - ALK1 represents a linear or branched, optionally cyclic, saturated or unsaturated divalent 10 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, 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, ALK1 represents a (C1-C6)alkylene and more preferentially (C1-C4)alkylene group such as propylene; 15 - n and m, which may be identical or different, represent an integer greater than 2 and more particularly the values of m and n are such that the weight-average molecular weight of said polyorganosiloxane is between 1000 and 55000 g.mol-1. As examples of polythiol compounds of formula (XIII), mention may be made of those sold by the company Genesee Polymers under the names GP-367, GP-71-SS, GP-800 and GP- 20 710s, preferably GP-367, sold by the company Genesee Polymers. The polythiol compounds 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 / mercapto-functional, https: / / www.shinetsusilicone-global.com / products / type / oil / detail / search / deg07.shtml, and 25 1053_Reactive Silicones_Silanes / Silicones – Gelest. According to a particular embodiment of the invention, the (poly)thiol compounds are chosen from hyperbranched polymers comprising at least one thiol group and dendrimers bearing at least one thiol group, such as thiolated PAMAM dendrimers. Preferably, the (poly)thiol compounds used according to the invention are chosen from 30 polydiallylsiloxanes, notably polydimethylsiloxanes, including at least two thiol groups such as those of formula (XIII). 68 According to a particular embodiment, the process according to the invention comprises the application of at least one (poly)acrylate compound crosslinking agent. The term “(poly)acrylate” means a compound which comprises at least one acrylate ester 5 group H2C=C(Re)-C(O)-Y- with Rerepresenting a hydrogen atom or a (C1-C4)alkyl group, such as methyl, preferably Rerepresenting a hydrogen atom, and Y representing an oxygen atom or an amino group -N(H)-, preferably an oxygen atom. More particularly, the (poly)acrylate(s) of the invention are of formula (XIV): L[-Y-C(O)-C(Re)=CH2]q (XIV) 10 in which formula (XIV) q and L are as defined in formula (VIII), Y and Rebeing as defined previously, preferably Y = O and Re= H. According to a preferred embodiment, the compounds of formula (XIV) are such that L represents a di- or trivalent, preferably trivalent, hydrocarbon-based chain comprising from 1 to 8 carbon atoms, q is 2 or 3, preferably 3, Y represents O, and Rerepresents a hydrogen 15 atom. According to a particular embodiment, the (poly)acrylate compounds are chosen from polyorganosiloxanes including at least one acrylate group on the side chain, such as those of formula (XV): Ra-Si(Rb)(Rd)-O-[Si(Ra)(Rb)-O]m-[Si(Rb)(ALK1-Y-C(O)-C(Re)=CH2)-O]n-Si(Rb)(Rd)-Ra20 (XV) in which formula (XV): - Ra, Rband Rdare as defined for formula (XIII), preferably Ra, Rband Rdrepresent a (C1- C6)alkyl group, such as methyl, - ALK1is as defined for formula (XIII), preferably ALK1represents a (C1-C6)alkylene group, 25 more preferentially a (C1-C4)alkylene group, such as propylene, - n and m, which may be identical or different, represent an integer greater than 2 and more particularly the values of m and n are such that the weight-average molecular weight of said polyorganosiloxane is between 1000 and 55000 g.mol-1. - Y is as defined previously, and is preferably an oxygen atom. 30 More particularly, the (poly)acrylate compound may be 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 69 diacrylate, 1,6-hexanediol ethoxylate diacrylate, hydroxypivalyl hydroxypivalate, neopentyl glycol diacrylate, neopentyl glycol propoxylate (1PO / OH) diacrylate, pentaerythrityl tetraacrylate, pentaerythrityl triacrylate, poly(propylene glycol) diacrylate, tricyclo[5.2.1.02,6]decanedimethanol diacrylate, trimethylolpropane ethoxylate (1EO / OH) 5 methyl ether diacrylate, trimethylolpropane propoxylate triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tri(propylene glycol) diacrylate, trimethylolpropane triacrylate, and tris[2-(acryloyloxy)ethyl] isocyanurate. The (poly)acrylate compound may also be chosen from N,N’-methylenebisacrylamide. According to this embodiment, the (poly)acrylate compound is combined in its 10 implementation with an amine catalyst as described, for example, in 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 (1,8-15 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). More particularly, the (poly)acrylate compounds are chosen from those of formula (XIV), notably trimethylolpropane triacrylate, and those of formula (XV), more preferentially from 20 those of formula (XIV), notably trimethylolpropane triacrylate. D) Metal alkoxides According to a particular embodiment, the process according to the invention comprises the application of at least one crosslinking agent R chosen from the metal alkoxides of formulae 25 (XIVa), (XIVb), (XIVc) and (XIVd) below and mixtures thereof: • M-(OR1)n (XIVa) • R-M-(OR1)n-1(XIVb) • (R1O)n-1-M-R’’-M’-(OR1’)n’-1(XIVc) • R-M(R’)-(OR1)n-2 (XIVd) 30 in which formulae (XIVa), (XIVb), (XIVc) and (XIVd): - M and M’, which may be identical or different, represent an atom chosen from alkaline- earth metals, transition metals, metals of the lanthanide family, post-transition metals such 70 as aluminum or tin and metalloids such as boron; preferably transition metals such as Ti and post-transition metals such as aluminum; - n and n’ respectively represent the valencies of the atoms represented by M and M’; - R1and R1’, which may be identical or different, represent a linear or branched, saturated 5 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 hydrocarbon- based 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, 10 branched, acyclic 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-, -N(R2)-, -S- or a linear, cyclic or branched, saturated or unsaturated 15 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. 20 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 organometallic compound(s) are chosen from the alkoxides of formula 25 (XIVa) as defined previously. According to this preferred embodiment, the organometallic compound(s) are more particularly chosen from the alkoxides of formula (XIVa), in which M represents an atom chosen from transition metals, metals of the lanthanide family, post- transition metals, such as aluminum, tin, metalloids, such as boron, or alkaline-earth metals, such as magnesium or calcium; n represents the valency of the atom represented by M; R1 30 represents a saturated, linear or branched, hydrocarbon-based group containing from 1 to 30 carbon atoms, preferably from 1 to 6 carbon atoms. 71 According to another more preferred embodiment, the organometallic compound(s) are chosen from the alkoxides of formula (XIVa), 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 aluminum or tin, metalloids, such as boron, and alkaline-earth 5 metals, such as magnesium, preferably M represents a titanium atom; n represents the valency of the atom represented by M, notably 1, 2, 3 or 4, in particular 4; R1 represents a methyl, ethyl, 2-ethylhexyl, propyl, isopropyl, n-butyl, isobutyl or t-butyl group. According to an even more preferred embodiment, the organometallic compound(s) are chosen from zirconium ethoxide (Zr(OC2H5)4), zirconium propoxide (Zr(OCH2CH2CH3)4), 10 zirconium isopropoxide (Zr(OCH(CH3)2)4), zirconium butoxide Zr(OCH2CH2CH2CH3)4, zirconium tert-butoxide (Zr(OC(CH3)3)4), titanium ethoxide (Ti(OC2H5)4), titanium propoxide (Ti(OCH2CH2CH3)4), titanium isopropoxide (Ti(OCH(CH3)2)4), titanium butoxide (Ti(OCH2CH2CH2CH3)4), titanium tert-butoxide (Ti(OC(CH3)3)4), titanium 2- ethylhexyloxide (Ti(OCH2CH(C2H5)(CH2)3CH3)4), and mixtures thereof, more 15 preferentially chosen from zirconium propoxide, titanium propoxide, titanium butoxide and mixtures thereof. More preferentially, the crosslinking agent R is a compound of formula (XIVa) preferably in which M represents an atom chosen from transition metals, notably titanium such as titanium butoxide. 20 E) (Poly)carbonyl compounds According to a particular embodiment, the process according to the invention comprises the application of at least one (poly)carbonyl compound crosslinking agent R. In particular, the (poly)carbonyl compound is chosen from terephthalaldehyde, 5,5- 25 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, and nonionic or anionic 30 oxidized polysaccharides such as oxidized inulins, notably those of formula (II) as defined hereinbelow. In particular, the (poly)carbonyl compounds include a saturated or unsaturated, aromatic C5-C7 carbocycle, preferably aromatic, such as phenyl, or non-aromatic and 72 saturated such as cyclohexyl, more preferentially unsaturated and aromatic, such as terephthalaldehyde. According to a particular embodiment, the (poly)carbonyl compound(s) are chosen from nonionic or anionic oxidized polysaccharides comprising one or more aldehyde groups, and 5 optionally one or more anionic groups. These anionic groups are preferably carboxyl or carboxylate groups. The nonionic or anionic oxidized polysaccharides according to the invention may be represented by formula (II) below: P–(CHO)m (COOQ)n (II) 10 in which formula (II): - P represents a polysaccharide chain preferably consisting of monosaccharides comprising 5 carbon atoms or more than 5 carbon atoms, preferably 6 or more than 6 carbon atoms and more particularly 6 carbon atoms; - Q is chosen from a hydrogen atom, the ions derived from an alkali metal or an alkaline- 15 earth metal such as sodium or potassium, ammonia, organic amines such as monoethanolamine, diethanolamine, triethanolamine and 3-amino-1,2-propanediol or 2- amino-1,3-propanediol and basic amino acids such as lysine, arginine, sarcosine, ornithine and citrulline; - m + n is greater than or equal to 1; 20 - m is such that the degree of substitution of the polysaccharide with one or more aldehyde groups (DS(CHO)) is within the range from 0.001 to 2 and preferably from 0.005 to 1.5; - n is such that the degree of substitution of the polysaccharide with one or more carboxylic groups (DS(COOX)) is within the range from 0 to 2 and preferably from 0.001 to 1.5. The expression “degree of substitution DS(CHO) or DS(COOX) of the polysaccharides 25 according to the invention” means the ratio between the number of carbons oxidized to give an aldehyde or carboxylic group for all the repeating units and the number of elementary monosaccharides (even opened by preoxidation) constituting the polysaccharide. The groups CHO and COOX may be obtained during the oxidation of certain carbon atoms, for example on the carbon atoms 2, 3 or 6, of a saccharide unit containing 6 carbon atoms. 30 Preferably, the oxidation may take place on carbons 2 and 3, more particularly of 0.01% to 75% by number, and preferably of 0.1% to 50% by number of the rings that may have been opened. 73 The polysaccharide chain, represented by P, is preferably chosen from celluloses, starches, maltodextrins, guar gums, xanthan gums, pullulan gums, agar-agar gums, carrageenan gums, gellan gums, acacia gums, polyxylans and tragacanth gums, and derivatives thereof. The term “derivative” means the compounds obtained by chemical modification of the 5 mentioned compounds. They may be esters, amides or ethers of said compounds. The oxidation may take place according to a process known in the art, for example according to the process described in FR 2 842 200, in document FR 2 854 161 or in the article “Hydrophobic films from maize bran hemicelluloses” by E. Fredon et al., Carbohydrate Polymers 49, pages 1 to 12 (2002). 10 Another oxidation process is described in the article “Water soluble oxidized starches by peroxide reaction extrusion” Industrial Crops and Products 7, R.E. Wing, J.L. Willet, 45- 52 (1997). According to this embodiment, the (poly)carbonyl compound is combined in its implementation with an amine catalyst as described in the articles Progress in coating 129, 15 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 (1,5-20 diazabicyclo[4.3.0]non-5-ene), and in particular 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 the compounds A) (poly)amines, B) (poly)thiols, C) (poly)acrylates, D) metal alkoxides and E) 25 (poly)carbonyl compounds, and preferably from polyamine, polythiol, polycarbonyl, polyacrylate, metal alkoxide compounds, amino alkoxysilanes including only one primary and / or secondary amine group, and mixtures thereof, optionally in combination with an amine catalyst, in particular chosen from piperidine, DMAP (dimethylaminopyridine), DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), DABCO (1,4-diazabicyclo[2.2.2]octane), DBN (1,5-30 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), DBN (1,5- diazabicyclo[4.3.0]non-5-ene), and in particular the catalyst is DBU (1,8- 74 diazabicyclo[5.4.0]undec-7-ene); more preferentially, the at least one crosslinking agent is chosen from spermidine, titanium butoxide (Ti(OCH2CH2CH2CH3)4), trimethylolpropane triacrylate, terephthalaldehyde, (3-aminopropyl)triethoxysilane (APTES), polydimethylsiloxanes comprising primary amine groups at the end of chains or on side 5 chains, for instance bis-cetearyl amodimethicone, 4,7,10-trioxa-1,13-tridecanediamine, polydimethylsiloxanes including at least two thiol groups, polyether triamines, in particular polyetheramines (or Jeffamine), chitosans (notably poly(D-glucosamine)), and mixtures thereof. According to one embodiment, the crosslinking agent(s) are chosen from A) (poly)amine 10 compounds, in particular from alkoxysilanes containing only one primary and / or secondary amine group, such as APTES, B) (poly)thiol compounds. In particular, said (poly)amine compounds A) are chosen from a) chitosans, such as poly(D- glucosamine), b) polyether diamines, particularly polyethylene glycol α,ω-diamine (bearing an amine function at the end of the chain), c) polyether triamines, such as polyetheramine 15 (or Jeffamine), d) aminoalkoxysilanes, such as APTES, and e) polydialkylsiloxanes comprising primary amine groups at the end of the chain or on side chains, in particular polydimethylsiloxanes comprising primary amine groups, such as bis(3-aminopropyl)- terminated poly(dimethoxysiloxane) (PDMS-diNH2) and amodimethicones comprising amine groups on side chains, such as bis-cetearyl amodimethicone, notably the product sold 20 by Momentive Performance Materials, and f) polyamine compounds NH2-alk-NH2, in which alk denotes a divalent C2-C20hydrocarbon-based chain, optionally interrupted with one or more heteroatoms chosen from -O-, -N(R)- with R denoting a hydrogen atom or a C1-C4 alkyl radical, such as spermidine. According to a preferred embodiment, said (poly)amine compounds A) are chosen from a) 25 chitosans, such as poly(D-glucosamine), c) polyether triamines, such as polyetheramine (or Jeffamine), and e) polydialkylsiloxanes comprising primary amine groups at the end of the chain or on side chains, in particular polydimethylsiloxanes comprising primary amine groups, such as bis(3-aminopropyl)-terminated poly(dimethoxysiloxane) (PDMS-diNH2) and amodimethicones comprising amine groups on side chains, such as bis-cetearyl 30 amodimethicone, notably the product sold by Momentive Performance Materials, and f) polyamine compounds NH2-alk-NH2, in which alk denotes a divalent C2-C20hydrocarbon- based chain, optionally interrupted with one or more heteroatoms chosen from -O-, -N(R)- 75 with R denoting a hydrogen atom or a C1-C4alkyl radical, such as spermidine or 4,7,10- trioxa-1,13-tridecanediamine. In particular, said (poly)thiol compounds B) are chosen from a) polydialkylsiloxanes bearing thiol functions, and b) alkoxysilanes bearing thiol functions, and in particular are chosen 5 from a) polydialkylsiloxanes bearing thiol functions, preferentially polydimethylsiloxanes comprising thiol groups on the side chain (such as mercaptopropyl), notably those of formula (XIII). In particular, said (poly)acrylate compounds C) are chosen from those of formula (XIV), notably trimethylolpropane triacrylate, and those of formula (XV), notably copolymers of 10 dimethylsiloxane and acryloxypropylmethylsiloxane, preferably trimethylolpropane triacrylate. According to a preferred embodiment, the crosslinking agent(s) ii) are chosen from: A) (poly)amine compounds chosen from: ia) chitosans such as poly(D-glucosamine), 15 ib) polyether diamines, in particular polyethylene glycol α,ω-diamines, bearing a chain-end amine function, ic) polyether triamines, in particular polyetheramines (or Jeffamine), id) aminoalkoxysilanes, in particular APTES, ie) polyamine compounds NH2-alk-NH2, in which alk denotes a divalent C2-C20 20 hydrocarbon-based chain, optionally interrupted with one or more heteroatoms chosen from -O-, -N(R)- with R denoting a hydrogen atom or a C1-C4alkyl radical, notably spermidine and 4,7,10-trioxa-1,13-tridecanediamine, and if) polydialkylsiloxanes comprising primary amine groups at the end of the chain or on side chains, in particular polydimethylsiloxanes comprising primary amine groups, more 25 particularly bis(3-aminopropyl)-terminated poly(dimethoxysiloxane) (PDMS-diNH2) and amodimethicones comprising amine groups on side chains, more particularly bis-cetearyl amodimethicone; B) (poly)thiol compounds chosen from: iia) polydialkylsiloxanes bearing thiol functions, and 30 iib) alkoxysilanes bearing thiol functions, 76 and in particular chosen from iia) polydialkylsiloxanes bearing thiol functions, preferably from polydimethylsiloxanes comprising thiol groups on the side chain, in particular mercaptopropyl, and more particularly chosen from the compounds of formula (XIII): Ra-Si(Rb)(Rd)-O-[Si(Ra)(Rb)-O]m-[Si(Rb)(ALK1-SH)-O]n-Si(Rb)(Rd)-Ra(XIII) 5 in which formula (XIII): - Raand Rb, which may be identical or different, preferably identical, represent a (C1- C4)alkyl group, in particular methyl, a (C1-C4)alkoxy group, in particular methoxy, an aryl group, in particular phenyl, an aryloxy group, in particular phenoxy, an aryl(C1-C4)alkyl group, in particular benzyl, or an aryl(C1-C4)alkoxy group, in particular benzoxy, and 10 preferably a (C1-C4)alkyl group, more preferentially methyl, - Rdrepresents a (C1-C4)alkyl group, in particular methyl, a (C1-C4)alkoxy group, in particular methoxy, an aryl group, in particular phenyl, an aryloxy group, in particular phenoxy, an aryl(C1-C4)alkyl group, in particular benzyl, an aryl(C1-C4)alkoxy group, in particular benzoxy, or a (C1-C6)alkyl group substituted with a (C1-C4)alkylamino, amino or 15 thiol group, and preferably a (C1-C4)alkyl group, more preferentially methyl, and preferably Ra, Rband Rdare identical and represent a (C1-C6)alkyl group, more preferentially methyl, - ALK1represents a linear or branched, optionally cyclic, saturated or unsaturated divalent hydrocarbon-based chain comprising from 1 to 100 carbon atoms, optionally 20 interrupted with one or more heteroatoms such as oxygen, sulfur or nitrogen, in particular oxygen, a (thio)carbonyl group C(X) with X representing O or S, or combinations thereof, in particular –O–, –O-C(O)– or –C(O)-O–; preferably, ALK1 represents a (C1-C6)alkylene and more preferentially (C1-C4)alkylene group, even more preferentially propylene, - n and m, which may be identical or different, represent an integer greater than 2, and in 25 particular the values of m and n are such that the weight-average molecular weight of said polyorganosiloxane is between 1000 and 55000 g.mol-1; and C) the (poly)acrylate compounds of formula (XIV): L[-Y-C(O)-C(Re)=CH2]q(XIV) in which formula (XIV): 30 - q represents an integer greater than or equal to 2, in particular n is between 2 and 10 and preferably between 2 and 5 inclusive, 77 - L denotes a linear or branched, saturated or unsaturated, or (hetero)cyclic, saturated or unsaturated, multivalent (at least divalent) group, in particular comprising between 1 and 500 carbon and / or silicon atoms, more particularly between 2 and 40 carbon and / or silicon atoms, even more particularly between 3 and 30 carbon and / or silicon atoms, preferably 5 between 6 and 20 carbon atoms; L being optionally interrupted and / or terminated with one or more heteroatoms or groups chosen from O, S, N, Si, C(X), and combinations thereof, in particular -O-, -O-C(X)-, -N(R)-C(X)-, -Si(Rc)(Rd)-O- with R representing a hydrogen atom or a (C1-C6)alkyl group, in particular methyl; and / or L being optionally substituted with one or more groups chosen from: -N(Ra)Rb and -(X’)a-C(X)-(X’’)b-Ra; with X, X’ and X’’, which 10 may be identical or different, representing an oxygen or sulfur atom, or a group N(Rb); a and b being 0 or 1, preferably the sum of a + b being 1; Raand Rb, which may be identical or different, represent a hydrogen atom, a (C1-C6)alkyl group or an aryl(C1-C4)alkyl group, in particular benzyl, preferably Ra and Rb represent a hydrogen atom, and Rc and Rd, which may be identical or different, represent a (C1-C6)alkyl, aryl(C1-C4)alkyl or (C1-C6)alkoxy 15 group, - Rerepresents a hydrogen atom or a (C1-C4)alkyl group, in particular methyl; preferably, Rerepresents a hydrogen atom, and - Y represents an oxygen atom or an amino group -N(H)-, preferably an oxygen atom, preferably Y is an oxygen atom and Reis a hydrogen atom, preferably L represents a di- or 20 trivalent, preferably trivalent, hydrocarbon-based chain comprising from 1 to 8 carbon atoms, q is 2 or 3, preferably 3, and more preferentially, the compounds of formula (XIV) are trimethylolpropane triacrylate; D) metal alkoxides chosen from: zirconium ethoxide (Zr(OC2H5)4), zirconium propoxide (Zr(OCH2CH2CH3)4), zirconium isopropoxide (Zr(OCH(CH3)2)4), zirconium butoxide 25 Zr(OCH2CH2CH2CH3)4, zirconium tert-butoxide (Zr(OC(CH3)3)4), titanium ethoxide (Ti(OC2H5)4), titanium propoxide (Ti(OCH2CH2CH3)4), titanium isopropoxide (Ti(OCH(CH3)2)4), titanium butoxide (Ti(OCH2CH2CH2CH3)4), titanium tert-butoxide (Ti(OC(CH3)3)4), titanium 2-ethylhexyloxide (Ti(OCH2CH(C2H5)(CH2)3CH3)4), and mixtures thereof, more preferentially chosen from zirconium propoxide, titanium propoxide, 30 titanium butoxide and mixtures thereof, E) (poly)carbonyl compounds chosen from (poly)carbonyl compounds including a saturated or unsaturated, aromatic C5-C7 carbocycle, preferably aromatic, such as phenyl, or non- 78 aromatic and saturated such as cyclohexyl, more preferentially unsaturated and aromatic, such as terephthalaldehyde. COSMETIC ACTIVE AGENTS iv) 5 According to a particular embodiment, the process of the invention also comprises the application of iv) at least one cosmetic active agent, to said keratin materials. More particularly, in the treatment process according to the invention, at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” used comprises one or more cosmetic active agents. 10 In particular, the cosmetic active agent(s) iv) are chosen from: a) dyestuffs (or coloring agents), in particular chosen from pigments, direct dyes and mixtures thereof, b) active agents for caring for keratin materials, preferably the skin, c) UV-screening agents, and 15 d) mixtures thereof. According to a particular embodiment, the at least one cosmetic active agent is chosen from dyestuffs, preferably chosen from pigments, direct dyes and mixtures thereof, more preferentially pigments. According to another embodiment, at least one of the compositions “C1”, “C2”, “C3”, “C4” 20 or “C5” used comprises one or more cosmetic active agents chosen from a) dyestuffs (or coloring agents), in particular chosen from pigments, direct dyes and mixtures thereof, preferably chosen from pigments. According to a particular embodiment, composition “C1” contains at least one cosmetic active agent iv) as defined previously and hereinbelow, preferably chosen from a) dyestuffs, 25 and more preferentially chosen from pigments. According to a particular embodiment, composition “C2” contains at least one cosmetic active agent iv) as defined previously and hereinbelow, preferably chosen from a) dyestuffs, and more preferentially chosen from pigments. According to a particular embodiment, composition “C3” contains at least one cosmetic 30 active agent iv) as defined previously and hereinbelow, preferably chosen from a) dyestuffs, and more preferentially chosen from pigments. 79 Needless to say, a person skilled in the art will take care to select this or these optional cosmetic active agent(s), and / or the amount thereof, such that the advantageous properties of the corresponding composition according to the invention are not, or are not substantially, adversely affected by the envisaged addition. 5 DYESTUFFS According to a particular embodiment, the process of the invention uses one or more dyestuffs. More particularly, in the process of the invention, at least one of the compositions “C1”,10 “C2”, “C3”, “C4” or “C5” used comprises at least one particulate or non-particulate, water- soluble or water-insoluble dyestuff, preferably in a proportion of at least 0.01% by weight relative to the total weight of the composition considered. For obvious reasons, this amount is liable to vary significantly with regard to the intensity of the desired color effect and of the color intensity afforded by the dyestuffs under 15 consideration, and its adjustment clearly falls within the competence of a person skilled in the art. Preferably, at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” comprises at least one dyestuff chosen from pigments, direct dyes and mixtures thereof, more preferentially pigments. 20 More preferentially, the pigment(s) of the invention are chosen from carbon black, iron oxides, in particular yellow, red and black iron oxides, and micas coated with iron oxide, triarylmethane pigments, in particular blue and violet triarylmethane pigments, in particular Blue 1 Lake, azo pigments, in particular red azo pigments, more particularly D&C Red 7, an alkali metal salt of lithol red, in particular the calcium salt of lithol red B, and even more 25 preferentially chosen from red iron oxides, yellow iron oxides and azo pigments, in particular red azo pigments, more particularly D&C Red 7. PIGMENTS For the purposes of the invention, the term “pigment” means any compound that is capable 30 of imparting color to keratin materials. These compounds have a solubility in water at 25°C and at atmospheric pressure (760 mmHg) of less than 0.05% by weight, and preferably less than 0.01% by weight. 80 As pigments that are suitable for use in the invention, mention may notably be made of 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. 5 These pigments may be synthetic or natural. These pigments may be in pigment powder or paste form. They may be coated or uncoated. These 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. 10 A pigment that is suitable for use in the invention may be chosen from mineral pigments. The term "mineral pigment" refers to any pigment that satisfies the definition in Ullmann's Encyclopedia in the chapter on inorganic pigments. Among the mineral pigments that are useful in the present invention, mention may be made of manganese violet, ultramarine blue, chromium hydrate, ferric blue and titanium, zirconium or cerium oxides or dioxides, and 15 also of zinc, iron or chromium oxides. It may also be a pigment having a structure that may be, for example, of sericite / brown iron oxide / titanium dioxide / silica type. Such a pigment is sold, for example, under the reference Coverleaf NS or JS by the company Chemicals and Catalysts, and has a contrast ratio in the region of 30. They may also be pigments having a structure that may be, for example, of 20 silica microsphere type containing iron oxide. An example of a pigment having this structure is the product sold by the company Miyoshi under the reference PC Ball PC-LL-100 P, this pigment consisting of silica microspheres containing yellow iron oxide. Advantageously, the pigments may be iron oxides and / or titanium dioxides. A pigment that is suitable for use in the invention may be chosen from organic pigments. 25 The term “organic pigment” refers to any pigment that satisfies the definition in Ullmann’s Encyclopedia in the chapter on organic pigments. Among the organic pigments that are useful in the present invention, mention may be made of nitroso, nitro, azo, xanthene, pyrene, quinoline, anthraquinone, triphenylmethane, fluorane, phthalocyanine, metal-complex, isoindolinone, isoindoline, quinacridone, perinone, perylene, diketopyrrolopyrrole, indigo, 30 thioindigo, dioxazine, triphenylmethane and quinophthalone compounds. In particular, the white or colored organic pigments may be chosen from carmine, carbon black, aniline black, azo yellow, quinacridone, phthalocyanine blue, the blue pigments codified in the Color Index 81 under the references CI 42090, 69800, 69825, 74100, 74160, the yellow pigments codified in the Color Index under the references CI 11680, 11710, 19140, 20040, 21100, 21108, 47000, 47005, the green pigments codified in the Color Index under the references CI 61565, 61570, 74260, the orange pigments codified in the Color Index under the references CI 5 11725, 45370, 71105, the red pigments codified in the Color Index under the references CI 12085, 12120, 12370, 12420, 12490, 14700, 15525, 15580, 15620, 15630, 15800, 15850, 15865, 15880, 26100, 45380, 45410, 58000, 73360, 73915, 75470, the pigments obtained by oxidative polymerization of indole or phenol derivatives as described in patent FR 2679 771. 10 Examples that may also be mentioned include pigment pastes of organic pigments, such as the products sold by the company Hoechst under the names: Cosmenyl Yellow IOG: Yellow 3 pigment (CI 11710); Cosmenyl G yellow: Yellow 1 pigment (CI 11680); Cosmenyl GR orange: Orange 43 pigment (CI 71105); Cosmenyl R red: Red 4 pigment (CI 12085); Cosmenyl FB carmine: Red 5 pigment (CI 12490); Cosmenyl RL violet: Violet 23 pigment 15 (CI 51319); Cosmenyl A2R blue: Blue 15.1 pigment (CI 74160); Cosmenyl GG green: Green 7 pigment (CI 74260); Cosmenyl R black: Black 7 pigment (CI 77266). The pigments in accordance with the invention may also be in the form of composite pigments, as described in patent EP 1184426. These composite pigments may notably be composed of particles including an inorganic core, at least one binder for attaching the 20 organic pigments to the core, and at least one organic pigment which at least partially covers the core. The organic pigment may also be a lake. The term “lake” refers to dyes adsorbed onto insoluble particles, the assembly thus obtained remaining insoluble during use. 25 The inorganic substrates onto which the dyes are adsorbed are, for example, alumina, silica, calcium sodium borosilicate or calcium aluminum borosilicate, and aluminum. Among the dyes adsorbed on organic substrates, mention may be made of carminic acid. Mention may also be made of the dyes known under the following names: D & C Red 21 (CI 45380), D & C Orange 5 (CI 45370), D & C Red 27 (CI 45410), D & C Orange 10 (CI 45425), D & 30 C Red 3 (CI 45430), D & C Red 4 (CI 15510), D & C Red 33 (CI 17200), D & C Yellow 5 (CI 19140), D & C Yellow 6 (CI 15985) D & C Green 5 (CI 61570), D & C Yellow 10 (CI 77002), D & C Green 3 (CI 42053), D & C Blue 1 (CI 42090), FDC Red 4, D & C Red 82 6, D & C Red 22, D & C Red 28, D & C Red 30, D & C Orange 4, D & C Yellow 8, D & C Green 5, D & C Red 17, D & C Green 6, D & C Yellow 11, D & C Violet 2, Sudan red, carotenes (β-carotene, lycopene), xanthophylls (capsanthin, capsorubin, lutein), palm oil, Sudan brown, quinoline yellow, annatto, curcumin, betanin (beet), carmine, copper 5 chlorophyllin, methylene blue, anthocyanins (enocianin, black carrot, hibiscus, elderberry), riboflavin, beet juice and caramel. An example of a lake that may be mentioned is the product known under the following name: D&C Red 7 (CI 15850:1). The pigment may also be a special-effect pigment. 10 The term “pigments with special effects” means pigments that generally create a colored 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 colored pigments, which afford a standard uniform opaque, semi-transparent or transparent 15 shade. Several types of special-effect pigments exist: those with a low refractive index, such as fluorescent or photochromic pigments, and those with a higher refractive index, such as nacres, interference pigments or glitter flakes. The size of the pigment used in the composition according to the present invention is 20 generally between 10 nm and 200 µm, preferably between 20 nm and 80 µm and more preferentially between 30 nm and 50 µm. The pigments may be dispersed in the composition by means of a dispersant. 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 25 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. In particular, esters of 12- hydroxystearic acid in particular and of C8to C20fatty acid and of polyols such as glycerol or diglycerol are used, such as poly(12-hydroxystearic acid) stearate with a molecular weight 30 of approximately 750 g / mol, such as the product sold under the name Solsperse 21000 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 83 product sold under the reference Arlacel P100 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 5 mixtures such as those sold by the company Dow Corning under the references DC2-5185 and DC2-5225 C. The pigments used in the composition may be surface-treated with an organic agent. According to a particular embodiment, the dispersant(s) are of amino silicone type other than the alkoxysilanes described previously and are cationic. Preferably, the pigment(s) is (are) chosen from mineral, mixed mineral-organic, or organic pigments. 10 According to a particular embodiment, the pigment(s) according to the invention are organic pigments, preferentially organic pigments surface-treated with an organic agent chosen from silicone compounds. According to another embodiment of the invention, the pigment(s) according to the invention are mineral pigments. 15 DIRECT DYES According to a particular embodiment, the process according to the invention comprises the application of one or more direct dyes. The term “direct dye” means natural and / or synthetic dyes, other than oxidation dyes. These are dyes which will spread superficially on the fiber. 20 They may be ionic or nonionic, preferably cationic or nonionic. Among the direct dyes that are suitable for use in the invention, mention may be made of 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. 25 The direct dyes are preferably cationic direct dyes. Mention may be made of the hydrazono cationic dyes of formulae (A) and (B) below and the azo cationic dyes of formulae (C) and (D) below: Het+-C(Ra)=N-N(Rb)-Ar, Q- (A) Het+-N(Ra)-N=C(Rb)-Ar, Q- (B) 30 Het+-N=N-Ar, Q- (C) Ar+-N=N-Ar’’, Q- (D) in which formulae (A) to (D): 84 - Het+represents a cationic heteroaryl radical, preferentially bearing an endocyclic cationic charge, such as imidazolium, indolium or pyridinium, which is optionally substituted, preferentially with at least one (C1-C8)alkyl group such as methyl; - Ar+represents an aryl radical, such as phenyl or naphthyl, bearing an exocyclic cationic 5 charge, preferentially ammonium, particularly tri(C1-C8)alkylammonium, such as trimethylammonium; - Ar represents an aryl group, notably phenyl, which is optionally substituted, preferentially with one or more electron-donating groups such as optionally substituted (C1-C8)alkyl, optionally substituted (C1-C8)alkoxy, (di)(C1-C8)(alkyl)amino optionally substituted on the10 alkyl group(s) with a hydroxyl group, aryl(C1-C8)alkylamino, and optionally substituted N- (C1-C8)alkyl-N-aryl(C1-C8)alkylamino or alternatively Ar represents a julolidine group; - Ar’’ represents an optionally substituted (hetero)aryl group, such as phenyl or pyrazolyl, which are optionally substituted, preferentially with one or more (C1-C8)alkyl, hydroxyl, (di)(C1-C8)(alkyl)amino, (C1-C8)alkoxy or phenyl groups; 15 - Ra and Rb, which may be identical or different, represent a hydrogen atom or a (C1-C8)alkyl group, which is optionally substituted, preferentially with a hydroxyl group; or else the substituent Ra with a substituent of Het+and / or Rb with a substituent of Ar form, together with the atoms that bear them, a (hetero)cycloalkyl; in particular, Ra and Rb represent a hydrogen atom or a (C1-C4)alkyl group optionally substituted with a hydroxyl 20 group; - Q- represents an organic or mineral anionic counterion, such as a halide or an alkyl sulfate. In particular, mention may be made of the azo and hydrazono direct dyes bearing an endocyclic cationic charge of formulae (A) to (D) as defined previously, more particularly the cationic direct dyes bearing an endocyclic cationic charge described in 25 patent applications WO 95 / 15144, WO 95 / 01772 and EP 714954. Preferably, the direct dyes are chosen from the compounds of formulae (E) and (F) below: 85 (F) in which formulae (E) and (F): - R1represents a (C1-C4)alkyl group such as methyl; 5 - R2and R3, which may be identical or different, represent a hydrogen atom or a (C1-C4)alkyl group, such as methyl; - R4represents a hydrogen atom or an electron-donating group such as optionally substituted (C1-C8)alkyl, optionally substituted (C1-C8)alkoxy, or (di)(C1-C8)(alkyl)amino optionally substituted on the alkyl group(s) with a hydroxyl group; in particular, R4is a hydrogen atom; 10 - Z represents a CH group or a nitrogen atom, preferentially CH; - Q- is an anionic counterion as defined previously, in particular a halide, such as chloride, or an alkyl sulfate, such as methyl sulfate or mesyl. In particular, the dyes of formulae (E) and (F) are chosen from Basic Red 51, Basic Yellow 87 and Basic Orange 31 or derivatives thereof with Q- being an anionic counterion as defined 15 previously, particularly a halide such as chloride, or an alkyl sulfate such as methyl sulfate or mesyl. The direct dyes may be chosen from anionic direct dyes. The anionic direct dyes of the invention are dyes commonly referred to as “acid” direct dyes owing to their affinity for alkaline substances. The term “anionic direct dye” means any direct dye including in its structure at least one 20 CO2R’ or SO3R’ substituent with R’ denoting a hydrogen atom or a cation originating from a metal or an amine, or an ammonium ion. The anionic direct dyes may be chosen from direct nitro acid dyes, azo acid dyes, azine acid dyes, triarylmethane acid dyes, indoamine acid dyes, anthraquinone acid dyes, indigoid dyes and natural acid dyes. 25 Among the natural direct dyes that may be used according to the invention, mention may be made of lawsone, juglone, alizarin, purpurin, carminic acid, kermesic acid, purpurogallin, protocatechaldehyde, indigo, isatin, curcumin, spinulosin, apigenidin and orceins. Use may 86 also be made of extracts or decoctions containing these natural dyes and notably henna-based poultices or extracts. Preferably, the direct dyes are chosen from anionic direct dyes. The dyestuffs, preferably the pigments, may be present in concentrations ranging from 5 0.01% to 30% by weight, preferably from 0.02% to 20% by weight and more particularly from 0.05% to 15% by weight relative to the total weight of the composition containing them. The direct dye(s) may be present in concentrations ranging from 0.001% to 10% by weight and preferably from 0.005% to 5% by weight relative to the total weight of the composition 10 containing them. Preferably, the cosmetic active agent(s), in particular the dyestuff(s) and more particularly the pigment(s), are introduced into at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5”. 15 CARE ACTIVE AGENTS According to a particular embodiment, the process of the invention uses one or more care active agents. More particularly, in the process of the invention, according to one embodiment, at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” used comprises one or more care active 20 agents, preferably in a proportion of at least 0.01% by weight relative to the total weight of the composition considered. In particular, the care active agent may be at least one hydrophilic active agent and / or one lipophilic active agent, and preferably a hydrophilic care active agent. The term “hydrophilic active agent” means a water-soluble or water-dispersible active agent 25 that is capable of forming hydrogen bonds. The cosmetic care active agent(s) may notably be chosen from: a) vitamins and derivatives thereof, notably esters thereof, in particular tocopherol (vitamin E) and esters thereof (such as tocopheryl acetate), ascorbic acid (vitamin C) and derivatives thereof; b) humectants, in particular urea, hydroxyureas, glycerol, polyglycerols, glycerolglucoside, 30 diglycerolglucoside, polyglycerylglucosides and xylitylglucoside, and in particular glycerol; c) C-glycoside compounds; d) antioxidant compounds; e) anti-ageing active agents, in particular hyaluronic acid compounds, and notably sodium hyaluronate, retinol and 87 derivatives thereof, salicylic acid compounds and in particular n-octanoyl-5-salicylic acid (capryloyl salicylic acid), caffeine, adenosine, c-β-d-xylopyranoside-2-hydroxypropane and the sodium salt of (3-hydroxy-2-pentylcyclopentyl)acetic acid; f) skincare agents chosen from allantoin, panthenol and protein hydrolysates; g) polyphenols, notably escin, ruscus, 5 diosmin, hesperidin and resveratrol, and h) mixtures thereof. In particular, in the process of the invention, according to one embodiment, at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” used comprises a moisturizer (also known as a humectant agent). Preferably, the care active agent is a moisturizer, and in particular is glycerine (glycerol). 10 The care active agent(s) may in particular be present, in the composition containing same, in a content ranging from 0.01% to 30% by weight, relative to the weight of the composition, and preferably from 0.02% to 25% by weight. UV-SCREENING AGENTS 15 According to one embodiment of the process of the invention, at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” used comprises, as cosmetic active agent, at least one UV-screening agent. The UV-screening agent is a UV-screening agent normally used in cosmetics. It may be chosen from the positive list contained in Annex VI of (EC) Regulation No. 20 1223 / 2009, which specifies the list of UV-screening agents permitted in cosmetics. The UV-screening agents that are suitable for use in the invention may be of varied nature. They may be lipophilic, hydrophilic or insoluble organic agents. The term “lipophilic UV-screening agent” means any cosmetic or dermatological screening agent that can be fully dissolved in molecular form in a liquid fatty phase or that can be 25 dissolved in colloidal form (for example in micellar form) in a liquid fatty phase. The term “hydrophilic UV-screening agent” means any cosmetic or dermatological screening agent that can be fully dissolved in molecular form in a liquid aqueous phase or that can be dissolved in colloidal form (for example in micellar form) in a liquid aqueous phase. 30 The term “insoluble UV-screening agent” means any cosmetic or dermatological screening agent which is not defined either as a lipophilic UV-screening agent or as a hydrophilic UV- screening agent, and which is in the form of particles in aqueous phase or liquid fatty phase. 88 The UV-screening agents of the composition according to the invention may afford UVA and / or UVB photoprotection. According to a preferred embodiment, the compositions, which are preferably cosmetic compositions, may comprise at least one organic and / or mineral UV-screening agent (for 5 screening out the UV radiation of sunlight). In particular, the UV-screening agent(s) are chosen from bis-resorcinyl triazine derivatives, dibenzoylmethane derivatives, benzylidenecamphor derivatives, and mixtures thereof. The organic UV-screening agents may also be chosen from anthranilic derivatives; cinnamic derivatives; salicylic derivatives; benzophenone derivatives; phenylbenzotriazole 10 derivatives; benzalmalonate derivatives, notably those mentioned in patent US 5624663; phenylbenzimidazole derivatives; imidazolines; 4,4-diarylbutadiene derivatives; bis- benzazolyl derivatives, as described in patents EP 6 693 23 and US 2 463 264; p- aminobenzoic acid (PABA) derivatives; methylenebis(hydroxyphenylbenzotriazole) derivatives, as described in patent applications US 5237071, US 5166355, GB 2303549, 15 DE 19726184 and EP 893119; benzoxazole derivatives, such as those described in patent applications EP 0 832 642, EP 1 027 883, EP 1 300 137 and DE 101 62 844; screening polymers and screening silicones such as those notably described in patent application WO 93 / 04665; α-alkylstyrene-based dimers such as those described in patent application DE 198 55649; 4,4-diarylbutadienes such as those described in patent applications EP 0967200, 20 DE 197 46 654, DE 197 55 649, EP 1 008 586, EP 1 133 980 and EP 133 981; other merocyanine derivatives such as those described in patent applications WO 04 / 006878, WO 05 / 058269 and WO 06 / 032741, and mixtures thereof. According to a particular embodiment, the concentration of the organic UV-screening agents in the compositions ranges from 1% to 50% by weight, preferably from 1% to 40% by 25 weight, for example from 5% to 35% by weight, relative to the total weight of the composition. The UV-screening agent(s) may be mineral UV-screening agents, which are generally pigments that are preferably uncolored. The pigments may or may not be coated. Thus, the mineral UV-screening agents may be chosen from coated or uncoated pigments, 30 and in particular from coated titanium oxide pigments, silicone-treated titanium oxides, uncoated titanium oxide pigments, uncoated zinc oxide pigments, coated zinc oxide 89 pigments, uncoated cerium oxide pigments, uncoated iron oxide pigments, coated iron oxide pigments, and mixtures thereof. According to a particular embodiment, compositions “C1” to “C5” are free of mineral UV- screening agents. 5 According to a particular embodiment, the amount of the mineral UV-screening agent(s) present in compositions “C1”, “C2”, “C3”, “C4” or “C5” may range from 0.01% to 20% by weight relative to the total weight of the composition containing same. It ranges, for example, from 1% to 15% by weight, relative to the total weight of the composition. According to a particular embodiment, at least one of the compositions “C1” to “C5” also 10 comprises one or more organic UV-screening agents and one or more mineral UV-screening agents. According to a particular embodiment, the compositions comprise a combination of UV- screening agents as described in patent FR 2977490, patent application WO 2013 / 004777 or patent application US 2014 / 0134120. 15 Preferably, the process for treating keratin materials, notably keratin fibers, and compositions “C1”, “C2”, “C3”, “C4” or “C5” comprise the application of or comprise one or more dyestuffs chosen from pigments, direct dyes and mixtures thereof, preferably pigments; more preferentially, the pigment(s) of the invention are chosen from carbon black, iron oxides, notably yellow, red and black iron oxides, and micas coated with iron oxide, 20 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, an alkali metal salt of lithol red, such as the calcium salt of lithol red B, even more preferentially red iron oxides, yellow iron oxides and azo pigments, notably red azo pigments, such as D&C Red 7. 25 FATTY PHASE - FATTY SUBSTANCES According to a particular embodiment, the process of the invention comprises the application of v) one or more fatty substances, in particular one or more oils. In particular, at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” used in the process of the invention contains a fatty phase. 30 In particular, at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” used in the process of the invention comprises one or more fatty substances, different from the compounds i), in particular one or more oils, preferably volatile oils. 90 The term “oil” refers to a fatty substance that is liquid at room temperature (20°C) and atmospheric pressure (760 mmHg). The term “hydrocarbon-based oil” means an oil formed essentially from, or even constituted of, carbon and hydrogen atoms, and possibly oxygen and nitrogen atoms, and not containing 5 any silicon or fluorine atoms. It may contain alcohol, ester, ether, carboxylic acid, amine and / or amide groups. According to one embodiment of the invention, the oil(s) v) are chosen from volatile oils, in particular: - hydrocarbon-based oils containing from 8 to 16 carbon atoms, in particular branched 10 C8-C16alkanes, in particular isoalkanes, more particularly isoalkanes (also known as isoparaffins), preferably C13-C16isoparaffins, isododecane, isodecane, isohexadecane, for example the oils sold under the trade names Isopar or Permethyl, alone or as mixtures, preferably isododecane (also known as 2,2,4,4,6-pentamethylheptane), linear alkanes, in particular C11-C16alkanes, alone or as mixtures, in particular hexane, decane, undecane,15 tridecane, isoparaffins, in particular n-dodecane (C12) and n-tetradecane (C14), the undecane- tridecane mixture, mixtures of n-undecane (C11) and n-tridecane (C13), and mixtures thereof and also mixtures of n-undecane (C11) and n-tridecane (C13), and volatile C5-C12cyclic, non- aromatic alkanes; - short-chain esters containing from 3 to 8 carbon atoms in total, in particular ethyl 20 acetate, methyl acetate, propyl acetate or n-butyl acetate; - carbonate hydrocarbon-based oils of structure R’1-O-C(O)-O-R’2in which R’1and R’2independently denote a linear, branched or cyclic C4-C8 alkyl group, preferably a C4-C8 alkyl group, advantageously chosen more preferentially from dibutyl carbonate or dipentyl carbonate; 25 - ether oils of formula R1-O-R2 in which R1 and R2, independently of each other, denote a linear, branched or cyclic C4-C8 alkyl group, preferably a C4-C8 alkyl group; - silicone oils, in particular comprising from 2 to 7 silicon atoms, and optionally including alkyl or alkoxy groups containing from 1 to 10 carbon atoms, in particular dimethicones of viscosity 5 and 6 cSt, cyclopentadimethylsiloxane, dodecamethylpentasiloxane, 30 cyclohexadimethylsiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, heptamethylhexyltrisiloxane, 91 heptamethyloctyltrisiloxane, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, dodecamethylpentasiloxane, and mixtures thereof; more preferentially, the volatile oil(s) v) are chosen from C8-C16 alkanes, in particular branched alkanes, preferably isododecane. 5 In particular, at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” used in the process according to the invention comprises one or more non-volatile oils, preferably chosen from: - non-volatile fluoro oils, in particular chosen from fluorinated polyethers, fluorosilicone oils and fluorosilicones; 10 - non-volatile silicone oils, in particular chosen from non-volatile silicones having the following INCI names: dimethicone, dimethiconol, trimethyl pentaphenyl trisiloxane, tetramethyl tetraphenyl trisiloxane, diphenyl dimethicone, trimethylsiloxyphenyl dimethicone, phenyl trimethicone, diphenylsiloxy phenyl trimethicone; and mixtures thereof; 15 - non-volatile apolar hydrocarbon-based oils, in particular chosen from linear or branched compounds of mineral or synthetic origin: i) liquid paraffin, ii) squalane, isoeicosane, iii) mixtures of linear, saturated hydrocarbons, more particularly C15-C28hydrocarbons, in particular mixtures whose INCI names are (C15-C19)Alkane, (C18-C21)Alkane, (C21- C28)Alkane, iv) hydrogenated or non-hydrogenated polybutenes; v) hydrogenated or non-20 hydrogenated polyisobutenes, preferably hydrogenated, vi) hydrogenated or non- hydrogenated polydecenes, vii) decene / butene copolymers, butene / isobutene copolymers and viii) mixtures thereof; - non-volatile polar hydrocarbon-based oils, which may be chosen from: i) saturated, unsaturated, linear or branched C10-C26fatty alcohols, preferably monoalcohols; 25 in particular, the C10-C26 alcohols are fatty alcohols, which are preferably branched when they comprise at least 16 carbon atoms; preferably, the fatty alcohol comprises from 10 to 24 carbon atoms, and more preferentially from 12 to 22 carbon atoms, in particular such as lauryl alcohol, isostearyl alcohol, oleyl alcohol, 2-butyloctanol, 2-undecylpentadecanol, 2- hexyldecyl alcohol, isocetyl alcohol, octyldodecanol and mixtures thereof; 30 ii) triglycerides consisting of fatty acid esters of glycerol, in particular the fatty acids of which may have chain lengths ranging from C4to C36, and notably from C18to C36, these oils possibly being linear or branched, and saturated or unsaturated; by way of example, 92 mention may notably be made of heptanoic or octanoic triglycerides, caprylic / capric acid triglycerides, plant oils such as wheatgerm oil, sunflower oil, grapeseed oil, sesame seed oil, corn oil, apricot kernel 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, 5 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, passionflower oil, musk rose oil, groundnut oil, coconut oil, argan oil, passionflower oil, kaya oil; the liquid fraction of shea butter, and the liquid fraction of cocoa butter; and also mixtures thereof; iii) linear aliphatic hydrocarbon-based esters of formula R-C(O)-OR’ in which R-C(O)-O- 10 represents the carboxylic acid residue containing from 2 to 40 carbon atoms, and R’ represents a hydrocarbon-based chain containing from 1 to 40 carbon atoms, aliphatic hydrocarbon-based esters of alkylene glycol, in particular ethylene glycol or propylene glycol; the total number of carbon atoms in particular being at least 10; notably chosen from isoamyl laurate, cetostearyl octanoate, isopropyl myristate, isopropyl palmitate, isopropyl 15 stearate or isostearate, ethyl palmitate, 2-ethylhexyl palmitate, isostearyl isostearate, octyl stearate, isostearyl heptanoate, octanoates, decanoates or ricinoleates of alcohols or of polyalcohols, such as propylene glycol dioctanoate, cetyl octanoate, tridecyl octanoate, 2- ethylhexyl palmitate, alkyl benzoate, polyethylene glycol diheptanoate, propylene glycol bis(2-ethylhexanoate) and mixtures thereof, hexyl laurate, neopentanoic acid esters, such as20 isodecyl neopentanoate, isotridecyl neopentanoate, isostearyl neopentanoate or 2- octyldodecyl neopentanoate, isononanoic acid esters, in particular isononyl isononanoate, isotridecyl isononanoate or octyl isononanoate, oleyl erucate, isopropyl lauroyl sarcosinate, diisopropyl sebacate, isocetyl stearate, isodecyl neopentanoate, isostearyl behenate or myristyl myristate; 25 iv) hydroxylated esters, in particular polyglyceryl-2 triisostearate; v) aromatic esters, in particular tridecyl trimellitate, C12-C15 alcohol benzoate, the 2- phenylethyl ester of benzoic acid, and butyloctyl salicylate; vi) linear fatty acid esters with a total carbon number ranging from 35 to 70, in particular pentaerythrityl tetrapelargonate; 30 vii) esters of C24-C28branched fatty acids or fatty alcohols, in particular triisoarachidyl citrate, pentaerythrityl tetraisononanoate, glyceryl triisostearate, glyceryl tris(2- 93 decyltetradecanoate), pentaerythrityl tetraisostearate, polyglyceryl-2 tetraisostearate or pentaerythrityl tetrakis(2-decyltetradecanoate); viii) the polyesters obtained by condensation of dimer and / or trimer of unsaturated fatty acid and of diol, in particular those with the INCI name Dilinoleic Acid / Butanediol Copolymer 5 or Dilinoleic Acid / Propanediol Copolymer; the polyesters obtained by condensation of fatty acid dimer and of diol dimer, in particular dimer dilinoleyl dimer dilinoleate; ix) synthetic ethers containing from 10 to 40 carbon atoms, in particular dicaprylyl ether; x) dialkyl carbonates, the two alkyl chains possibly being identical or different, in particular dicaprylyl carbonate; 10 xi) vinylpyrrolidone copolymers, in particular vinylpyrrolidone / 1-hexadecene copolymer; and xii) mixtures thereof; - the non-volatile carbonate oils may be chosen from the carbonates of formula R8-O- C(O)-O-R9, with R8and R9, which may be identical or different, representing a linear or 15 branched C4to C12and preferentially C6to C10alkyl chain; the carbonate oils may be dicaprylyl carbonate (or dioctyl carbonate), bis(2-ethylhexyl) carbonate, dipropylheptyl carbonate, dibutyl carbonate, dineopentyl carbonate, dipentyl carbonate, dineoheptyl carbonate, diheptyl carbonate, diisononyl carbonate or dinonyl carbonate and preferably dioctyl carbonate; 20 - oils known as non-volatile ether oils of formula R1-O-R2in which R1and R2independently denote a linear, branched or cyclic C6-C24alkyl group, preferably a C6-C18alkyl group, and preferably C8-C12 alkyl group. It may be preferable for R1 and R2 to be identical. Linear alkyl groups that may be mentioned include a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl 25 group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an eicosyl group, a behenyl group, a docosyl group, a tricosyl group and a tetracosyl group. Branched alkyl groups that may be mentioned include a 1,1-dimethylpropyl group, a 3-methylhexyl group, a 5-methylhexyl group, an ethylhexyl group, a 2-ethylhexyl group, a 5-methyloctyl group, a 1-ethylhexyl group, a 1-butylpentyl 30 group, a 2-butyloctyl group, an isotridecyl group, a 2-pentylnonyl group, a 2-hexyldecyl group, an isostearyl group, a 2-heptylundecyl group, a 2-octyldodecyl group, a 1,3- dimethylbutyl group, a 1-(1-methylethyl)-2-methylpropyl group, a 1,1,3,3-tetramethylbutyl 94 group, a 3,5,5-trimethylhexyl group, a 1-(2-methylpropyl)-3-methylbutyl group, a 3,7- dimethyloctyl group and a 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyloctyl group. As cyclic alkyl groups, mention may be made of a cyclohexyl group, a 3-methylcyclohexyl group and a 3,3,5-trimethylcyclohexyl group, dilauryl ether, diisostearyl ether, dioctyl ether, 5 nonylphenyl ether, dodecyl dimethylbutyl ether, cetyl dimethylbutyl ether and mixtures thereof. Preferably, the non-volatile oil(s) are chosen from hydrogenated or non-hydrogenated polyisobutenes, preferably hydrogenated, in particular the non-volatile compounds of the Parleam®range; mixtures of C15-C19 alkanes, and from linear aliphatic hydrocarbon-based 10 esters of formula R-C(O)-OR’ in which R-C(O)-O represents a carboxylic acid residue containing from 2 to 40 carbon atoms, and R’ represents a hydrocarbon-based chain containing from 1 to 40 carbon atoms, as defined previously, in particular isononyl isononanoate. More preferentially, the process of the invention uses one or more hydrocarbon-based oils 15 containing from 8 to 16 carbon atoms, and notably branched C8-C16alkanes, in particular isoalkanes, preferably C13-C16 isoparaffins, isododecane, isodecane, isohexadecane, alone or as mixtures, and more preferentially isododecane. According to a preferred embodiment, the process of the invention uses one or more fatty substances v), different from the polyesters of formula (I), in particular at least one oil, 20 preferably at least one volatile oil, more preferentially at least one hydrocarbon-based volatile oil. In particular, the amount of oil(s), different from the compounds i), in at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” used in the process according to the invention ranges from 1% to 99% by weight, relative to the total weight of the composition, more 25 particularly from 2% to 98% by weight, preferentially from 3% to 97%, better still from 5% to 96% by weight, relative to the total weight of the composition. According to another particular embodiment, the process of the invention does not use any fatty substances v) different from the compounds of formula (I). According to yet another embodiment, at least one of the compositions “C1”, “C2”, “C3”, 30 “C4” or “C5” used in the process according to the invention contains a mixture of fatty substances v) different from the compounds i), and chosen from mixtures of at least one 95 volatile oil, preferably a hydrocarbon-based oil, and at least one non-volatile oil, such as octyldodecanol. COMPOSITIONS 5 Another object of the invention is compositions, in particular cosmetic compositions, containing at least one polyester of formula (I), and also the optical or geometrical isomers thereof and / or the solvates thereof, such as hydrates, more particularly compositions, notably cosmetic compositions, containing at least one polyester of formula (I), as described previously. 10 Another subject of the invention is compositions, notably cosmetic compositions, containing at least one compound chosen from the polyesters P1 to P7, as described previously, and also the salts, isomers and solvates thereof. According to a particular embodiment, the process for treating keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or 15 for caring for, styling and / or coloring keratin fibers, preferably the hair, according to the invention, uses water or an organic solvent. Thus, according to a variant, at least one of the compositions “C1” to “C5” used in the process of the invention comprises water. According to this variant, the compositions “C1”, “C2”, “C3”, “C4” and / or “C5” are aqueous or aqueous-alcoholic compositions. 20 According to one embodiment, the process for treating keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or coloring keratin fibers, preferably the hair, according to the invention does not use water. Thus, according to this variant, the compositions “C1”, “C2”, “C3”, “C4” and / or “C5” are anhydrous compositions. 25 According to a particular embodiment, at least one of the compositions “C1”, “C2”, “C3”, “C4” and / or “C5” comprises an isododecane / ethanol mixture, in particular in a volume ratio of between 1 / 99 and 99 / 1, more particularly between 5 / 95 and 95 / 5. According to a particular embodiment, at least one of the compositions “C1”, “C2”, “C3”, “C4” and / or “C5” comprises an isododecane / octyldodecanol mixture, in particular in a 30 volume ratio of between 1 / 99 and 99 / 1, more particularly between 5 / 95 and 95 / 5. According to a particular embodiment, at least one of the compositions “C1”, “C2”, “C3”, “C4” or “C5” may be in the form of a water-in-oil emulsion or an oil-in-water emulsion. 96 According to a particular embodiment, the compositions “C1”, “C4” or “C5” may be in anhydrous, water-in-oil emulsion or oil-in-water emulsion form. According to a particular embodiment, composition “C4” is anhydrous. In particular, composition “C4” is anhydrous, and it comprises at least one oil, in particular a volatile oil, 5 preferably isododecane. According to another particular embodiment, composition “C4” comprises water. In particular, composition “C4” comprises water, and optionally at least one volatile or non- volatile oil, and / or at least one C1-C4alcohol such as ethanol or isopropanol, and / or at least one non-volatile oil. 10 The compositions “C1” to “C5” used in the process of the invention may also comprise one or more solvents, other than water. According to a particular embodiment of the invention, the polyester(s) of formula (I) as defined previously are used in a medium containing at least one solvent, preferably at least one polar and / or protic solvent, other than water. 15 According to this embodiment, composition “C1”, “C2”, “C3”, “C4” and / or “C5” used in the process of the invention comprises one or more solvents, preferably one or more polar and / or protic solvents other than water. Preferably, composition “C1”, “C2”, “C3”, “C4” and / or “C5” used in the process of the invention comprises at least one polar and / or protic solvent chosen from monoalcohols20 containing from 2 to 6 carbon atoms, in particular chosen from ethanol, propanol, n- butanol, isopropanol, isobutanol, tert-butanol, pentanol and hexanol, preferably n-butanol or ethanol, and even more preferentially ethanol. According to a preferred embodiment, the composition “C1”, “C2”, “C3”, “C4” and / or “C5” used in the process of the invention comprises at least one volatile or non-volatile oil, 25 and / or at least one C1-C4 alcohol such as ethanol or isopropanol, preferably comprises at least one solvent chosen from isododecane, 2-octyldodecanol, isononyl isononanoate, ethanol, and mixtures thereof. According to one embodiment, composition “C1”, “C2”, “C3”, “C4” and / or “C5” used in the process of the invention comprises one or more solvents other than water, in a content 30 of less than 95% by weight, more preferentially less than 92% by weight, relative to the total weight of the composition. According to one embodiment, composition “C2”, “C3” or “C4” is anhydrous. 97 According to another embodiment, composition “C4” is aqueous. Organic solvents that may also be mentioned include polyols that are miscible with water at room temperature (25°C), notably chosen from polyols notably containing from 2 to 10 carbon atoms, preferably containing from 2 to 6 carbon atoms, such as glycerol, propylene 5 glycol, 1,3-propanediol, butylene glycol, pentylene glycol, hexylene glycol, dipropylene glycol, diethylene glycol or diglycerol; polyol ethers, such as 2-butoxyethanol, propylene glycol monomethyl ether, diethylene glycol monoethyl ether or diethylene glycol monomethyl ether; and also aromatic alcohols, such as benzyl alcohol, and mixtures thereof. According to a particular embodiment, the composition also comprises one or more polyols 10 notably chosen from polyols notably containing from 2 to 10 carbon atoms, preferably containing from 2 to 6 carbon atoms, preferably glycerol. The compositions “C1”, “C2”, “C3”, “C4” or “C5” used in the process of the invention may also comprise one or more adjuvants commonly used in cosmetics, in particular chosen from thickeners, film-forming agents, gelling agents, trace elements, softeners, sequestrants, 15 fragrances, basifying or acidifying agents, dispersants, preserving agents, fillers, surfactants, propellants, polar additives, polymers, or mixtures thereof. Another subject of the invention is a composition termed “C2”, notably a cosmetic composition, comprising i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, the organic or mineral acid or base salts thereof, and / or the 20 solvates thereof, such as the hydrates, as defined previously, ii) at least one crosslinking agent, in particular as defined previously, and optionally iv) at least one cosmetic active agent, in particular as defined previously; preferably, composition “C2” does not comprise iv) a cosmetic active agent; Another subject of the invention is a composition, termed “C3”, in particular a cosmetic 25 composition, comprising i) at least one polyester of formula (I) and also the optical or geometrical isomers thereof, organic or mineral acid or base salts thereof, and / or solvates thereof, such as hydrates, as defined previously, ii) at least one crosslinking agent, in particular as defined previously, and iv) at least one cosmetic active agent, in particular as defined previously, preferably chosen from a) dyestuffs, preferably chosen from pigments, 30 direct dyes and mixtures thereof, and more preferentially from pigments. Another subject of the invention is the cosmetic use of composition “C2” as defined previously, for treating keratin materials, in particular for caring for and / or making up the 98 skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or dyeing keratin fibers, preferably the hair. Another subject of the invention is the cosmetic use of composition “C3” as defined previously, for treating keratin materials, in particular for caring for and / or making up the 5 skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or dyeing keratin fibers, preferably the hair. A composition “C1”, “C2”, “C3”, “C4” or “C5” is generally suitable for application to keratin materials, in particular application to the skin, lips and / or keratin fibers, and thus generally comprises a physiologically acceptable medium, i.e. a medium that is compatible 10 with keratin materials, in particular application to the skin, lips and / or keratin fibers, notably human keratin fibers such as the hair. The physiologically acceptable medium is preferably a cosmetically acceptable medium, i.e. a medium which has a pleasant color, odor and feel and which does not cause any unacceptable discomfort, i.e. stinging or tautness, liable to discourage the user from applying 15 this composition. A composition “C1”, “C2”, “C3”, “C4” or “C5” may be in the form of a makeup product, in particular a colored makeup product, for the skin, in particular a foundation, optionally having care properties, a blusher, a face powder, an eyeshadow, a concealer, an eyeliner; a lip makeup product such as a lipstick, optionally having care properties, a lip gloss or lip 20 pencils; a makeup product for the integuments such as the nails or eyelashes, in particular in the form of a mascara, or for the eyebrows and the hair, or a product for the temporary tattooing of bodily skin. According to a particular embodiment, a composition “C1”, “C2”, “C3”, “C4” or “C5” is in the form of: 25 - either a colored product for the lips; - or a skincare product, which may be colored, in particular a cream or a fluid having moisturizing and / or filling and / or tensor properties; or - or a haircare product, in particular a hair dyeing product or a styling product notably free of dyestuff, such as a lacquer, or a “styling” product of the mousse or gel type. 30 KIT 99 According to yet another of its aspects, the present invention is also directed toward a multi- compartment kit or device, notably a cosmetic kit or device, comprising: - at least one compartment containing i) at least one polyester of formula (I), as defined previously, and optionally iv) at least one cosmetic active agent, in particular as defined 5 previously, in particular comprising composition “C1” as defined previously; - at least one compartment different from the one which contains i) and containing ii) at least one crosslinking agent, in particular as defined previously, and optionally iv) at least one cosmetic active agent, in particular as defined previously, and in particular comprising composition “C4” as defined previously; and 10 - optionally, at least one compartment different from those containing i) and ii), and containing iv) at least one cosmetic active agent, in particular as defined previously, which may be identical to or different from that / those optionally contained in the compartments comprising i) and ii). Preferably, the compartment comprising at least i), in particular a composition “C1”, does 15 not comprise any crosslinking agent ii). Preferably, the compartment comprising at least one crosslinking agent ii), in particular a composition “C4”, does not contain i) any polyester of formula (I). Throughout the description, including the claims, the term "comprising a" should be 20 understood as being synonymous with "comprising at least one", unless otherwise mentioned. The expressions “between ... and ...”, “comprises from … to ...”, “formed from … to ...” and “ranging from ... to ...” are equivalent and are intended to mean that the limits are included, unless otherwise indicated. 25 The expression “at least one” is equivalent to “one or more”. The invention is illustrated in greater detail by the non-limiting examples presented below. Examples 30 Measurement and evaluation methods SKIN APPLICATION 100 a) One-step protocol The polyester(s) of formula (I) bearing acetoacetate functions or the alkyd resin(s) not bearing acetoacetate functions, a pigment, and a solvent are homogenized together in a Speedmixer (a mixing device that uses centrifugal force) for 2 minutes at 3500 rpm and at 5 room temperature. The crosslinking agent(s) and, optionally, the catalyst are introduced before or after the homogenization step. The compositions are applied to a Bioskin type vitro support from Maprecos (Bioskin plate #10) (elastomeric skin-simulating support) using a film spreader (wet thickness of 100 µm). The deposit is left to dry for 24 hours. 10 After 24 hours of drying, the deposits are evaluated according to the protocols described hereinbelow. b) Two-step protocol A first composition, known as the “base coat,” comprising the polyester(s) of formula (I) bearing acetoacetate functions or the alkyd resin(s) not bearing acetoacetate functions, a 15 pigment, a solvent and, optionally, a preferably nonvolatile oil such as 2-octyl-1-dodecanol or isononyl isononanoate, is prepared using a Speedmixer (a mixing device that uses centrifugal force) for 2 minutes at 3500 rpm and at room temperature. The composition is applied to a Bioskin type vitro support from Maprecos (Bioskin plate #10) (elastomer-based skin-simulating support) using a film spreader (wet thickness of 100 µm). The deposit is left 20 to dry for 24h. After this first action, a second composition, termed the “top coat”, comprising a crosslinking agent and optionally at least one oil, is applied in the same manner. The deposit is left to dry for 24 hours. After 24 hours of drying, the deposits are evaluated according to the protocols described 25 hereinbelow. RESISTANCE TO ADHESIVE TAPE A piece of adhesive tape (Scotch®Magic™ 810 from 3M; w = 19 mm, L = 5 cm) is applied to the formulation film obtained after drying for 24 hours. A weight of approximately 1070 30 g is placed on the piece of adhesive tape for 30 seconds. The piece of adhesive tape is then removed and mounted on a slide holder so as to properly observe the result. The adhesion of the film to the support is thus evaluated. 101 RESISTANCE TO OLIVE OIL / SEBUM / WATER 0.5 mL of olive oil, sebum or water is applied to the formulation film obtained after drying for 24 hours. After 5 minutes, the olive oil, sebum or water is removed by wiping 15 times 5 with cotton wool. The deterioration of the film following contact with the drop of aggressor is thus examined. In the case of a two-step protocol, for each combination, evaluations are performed on the “base coat” composition alone after drying, and on the system of “base coat” + “top coat” compositions after drying, the objective being to observe the cosmetic properties improved 10 by such combinations. The resistance is evaluated according to the following scale: +++: Cosmetic property evaluated as highly effective, no attack of the deposit, which is as it was originally; ++: Cosmetic property evaluated as moderately effective, a little transfer but the deposit 15 is as it was originally; +: Cosmetic property evaluated as poor, the deposit is slightly altered and some transfer is observed. 0: Cosmetic property evaluated as unsatisfactory, the deposit is completely degraded and there is a lot of transfer to the cotton wool. 20 FRAGMENTATION TEST OF THE FORMULATIONS ON BIOSKIN As for the tests of resistance to olive oil / sebum / water and to adhesive tape, films are applied to a sample of BioSkin. After drying for one day, the BioSkin plate is stretched, by hand force, 10 times. 25 The result is then be observed on the film (fragmentation or no fragmentation). The evaluation is made in the following manner: +++: cosmetic property evaluated as very effective; ++: cosmetic property evaluated as moderately effective; +: cosmetic property evaluated as not very effective; 30 0: cosmetic property evaluated as ineffective. GLOSS PERSISTENCE PROTOCOL 102 The compositions, comprising one or more polyesters of formula (I), bearing acetoacetate functions, or one or more alkyd resins not bearing acetoacetate functions, and / or a crosslinking agent and a solvent, are applied using an applicator (wet thickness of 100 µm) to a contrast chart (reference: byko-charts Opacity chart #2810). 5 Using a glossmeter, the gloss at 20° (angle of incidence) of the chart is measured, followed by measuring the gloss of the deposit 2 hours and then 24 hours after application. Once dry, 0.5 ml of water is deposited and left on for 5 minutes. The drops of aggressors are then rubbed off using cotton wool (15 strokes) and the gloss / mattness is measured on the attacked area (average of 5 measurements). 10 HAIR DYEING APPLICATION The hair dyeing evaluation protocol is detailed below: The evaluations are conducted according to three different protocols: in 1, 2 or 3 step(s), each on locks of natural hair containing 90% white hair strands. 15 a) One-step protocol The polyester(s) of formula (I) bearing acetoacetate functions, the pigment(s) and optionally the crosslinking agents, are mixed together before application. The system remains fluid long enough to allow application to the substrate. The composition is applied to locks of dry natural hair containing 90% white hair strands, at 20 a rate of 1 g of composition per gram of lock. The locks of hair are left for 5 minutes at room temperature. The locks of hair are then combed and dried with a hairdryer for 3 minutes. The locks of hair are left at room temperature for 24 hours. The hair is dyed uniformly and intensely. 25 The locks of hair thus dyed are then subjected to a test of several repeated shampoo washes so as to evaluate the fastness (persistence) of the coloring obtained with respect to shampoo washes, according to the shampoo washing protocol described below. b) Two-step protocol A first composition, termed the “base coat”, is applied to locks of dry natural hair containing 30 90% white hairs, in a proportion of 0.5 g of composition per gram of lock. The locks are then combed. This deposit is applied to the keratin materials, and then left for 3 hours at 103 room temperature (25°C). This drying step may be accelerated by heating the keratin material after application, for example using a hairdryer. After this first action, a second composition, termed the “top coat”, is applied to the lock of hair, at a rate of 0.5 g per gram of lock. 5 After application, the locks of hair are then dried with a hairdryer. The locks of hair are left at room temperature for 24 hours under a fume cupboard. The hair is dyed uniformly and intensely. The locks of hair thus dyed are then subjected to a test of several repeated shampoo washes so as to evaluate the fastness (persistence) of the coloring obtained with respect to shampoo 10 washes, according to the shampoo washing protocol described below. c) Three-step protocol A first composition containing one or more pigments alone or in the presence of one or more crosslinking agents conveyed in an organic solvent is applied to locks of dry natural hair containing 90% white hair strands, at a rate of 0.5 g of composition per gram of lock, and 15 the locks are then dried with a hair dryer. A second composition, known as a “base coat,” is applied to this dyed lock at a rate of 0.5 g of composition per gram of lock, and the locks are then dried with a hair dryer before being left to rest for 3 hours. After this second action, a third composition, termed the “top coat”, is applied to the lock of 20 hair, at a rate of 0.5 g per gram of lock. After application, the locks of hair are then dried with a hairdryer. The locks of hair are left at room temperature for 24 hours under a fume cupboard. The hair is dyed uniformly and intensely. The locks of hair thus dyed are then subjected to a test of several repeated shampoo washes 25 so as to evaluate the fastness (persistence) of the coloring obtained with respect to shampoo washes, according to the shampoo washing protocol described below. SHAMPOO WASHING PROTOCOL The locks of dyed hair are combed, moistened with water at 35°C and then passed between 30 the fingers five times for 5 seconds. The locks of hair are then squeezed dry between two fingers. 104 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 the length (6 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. 5 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. 10 PERSISTENCE PROTOCOL The persistence of the color of the locks was evaluated in the CIE L*a*b* system, using a Minolta Spectrophotometer CM3600A colorimeter (illuminant D65, angle 10°, specular component included). 15 In this L*a*b* system, L* represents the intensity of the color, a* indicates the green / red color axis and b* the blue / yellow color axis. The persistence of the coloring is evaluated by the color difference ΔE between the dyed locks before shampooing, then after having undergone one and three shampoo washes according to the protocol described above. The lower the ΔE value, the more persistent the 20 color with respect to shampoo washing. The ΔE value is calculated according to the following equation: In this equation, L*a*b* represent the values measured after dyeing the hair and after performing the shampoo washes, and L0*a0*b0* represent the values measured after dyeing 25 the hair but before shampoo washing. STEAMPOD PROTOCOL The polyester(s) of formula (I) and the crosslinking agents, are mixed together before application. The system remains fluid long enough to allow application to the substrate. 30 The composition is applied to locks of dry natural hair containing 90% white hair strands, at a rate of 1 g of composition per gram of lock. 105 The locks of hair are then combed and dried with a hairdryer for 1 minute and 30 seconds, and then a steam straightening iron (Steampod) is applied to said locks of hair with five passes at a temperature of 210°C. The locks of hair are then subjected to a test involving several repeated shampoo washes, 5 according to the shampoo washing protocol described previously. STYLING EVALUATION PROTOCOL The styling evaluation protocol is detailed below: A lock of hair (90% Natural White NW hair, length 20.5 cm) is wrapped around a brush 10 (approximate diameter of 2 cm over a length of 3 cm). 2 g of a solution containing the formulas described below are sprayed onto said lock. The lock is weighed before and after application. About 0.5 g of each composition is effectively deposited on the lock. The lock is left at room temperature, at 25°C. After 24 hours, the lock is released from the brush and suspended. The length of the lock is 15 then measured. After 24 hours of suspension, the length of the lock is again measured. A comparison of the curl maintenance is made between the compositions according to the invention and the comparative compositions.

[0002] 106 Example 1: Synthesis of a polyester bearing acetoacetate functions (polyester 1) Example 1.1 Alkyd resin 1 – outside the invention 5 Alkyd resin 1 was prepared from the reagents and contents indicated in the table below: Table 1 88 g of sebacic acid, 92 g of pentaerythritol and 220 g of isostearic acid are placed in a 0.5 L reactor equipped with a mechanical stirrer, a distillation column and an argon inlet. The reactor is maintained under an argon atmosphere throughout the synthesis by sparging. The 10 reaction medium is heated at 180°C for 1 hour, and then at 230°C for 7 hours, before cooling to room temperature. The alkyd resin is obtained in the form of a viscous oil that is cloudy at room temperature. The acid number Ia and the hydroxyl number IOHare measured. Ia = 2 mg KOH / g 15 IOH = 150 mg KOH / g

[0003] 107 Example 1.2 Polyester 1 - invention Polyester 1 was prepared from the reagents and contents indicated in the table below: Table 2 5 100 g of alkyd resin of Example 1.1 and 48 g of tert-butyl acetoacetate are introduced into a 250 mL round-bottomed flask equipped with a mechanical stirrer and a distillation column. The reaction medium is heated at 140-150°C on an oil bath. After 5 hours, the reaction medium is placed under continuous vacuum at 150°C for 1 hour. A viscous amber-colored 10 oil is obtained. Analysis by1H NMR spectrometry shows the presence of AcAc groups on the polyester obtained. Example 2: Synthesis of a polyester bearing acetoacetate functions (polyester 2) 15 Example 2.1 Alkyd resin 2 – outside the invention Alkyd resin 2 was prepared from the reagents and contents indicated in the table below: Table 3 20 92 g of homophthalic acid, 92 g of pentaerythritol and 216 g of isostearic acid are placed in a 0.5 L reactor equipped with a mechanical stirrer, a distillation column and an argon inlet. The reaction medium is heated at 190°C for 1 hour, and then at 230°C for 10 hours, before 108 cooling to room temperature. The alkyd resin is obtained in the form of a dark amber polymer. The acid number Ia and the hydroxyl number IOH are measured. Ia = 3.7 mg KOH / g 5 IOH= 140 mg KOH / g Example 2.2 Polyester 2 - invention Polyester 2 was prepared from the reagents and contents indicated in the table below: Table 4 10 300 g of alkyd resin of Example 2.1 and 118.65 g of tert-butyl acetoacetate are introduced into a 500 mL round-bottomed flask equipped with a mechanical stirrer and a distillation column. The reaction medium is heated at 150°C on an oil bath. After 5 hours, the reaction medium is placed under continuous vacuum at 150°C for 1 hour. An amber-colored polymer 15 is obtained. Analysis by1H NMR spectrometry shows the presence of AcAc groups on the polyester obtained. Example 3: Synthesis of a polyester bearing acetoacetate functions (polyester 3) 20 Example 3.1 Alkyd resin 3 – outside the invention Alkyd resin 3 was prepared from the reagents and contents indicated in the table below: Table 5 109 a) 87.42 g of xylitol and 126.39 g of octanoic acid are placed in a 0.5 L reactor equipped with a mechanical stirrer, a distillation column and an argon inlet. The reaction medium is gradually heated to a temperature of 180°C over 1 hour, and the temperature is then 5 maintained at 180°C for 5 hours. The acid number Ia is measured: Ia = 27.82 mg KOH / g. b) 86.19 g of sebacic acid are placed in the reactor. Heating is maintained at 180°C for 13 hours, and the medium is then heated at 180°C for 10 hours under vacuum (20 mbar). The alkyd resin is obtained in the form of a viscous amber oil. 10 The final acid number Ia and hydroxyl number IOHare measured. Ia = 12 mg KOH / g IOH = 206 mg KOH / g Example 3.2 Polyester 3 - invention 15 Polyester 3 was prepared from the reagents and contents indicated in the table below: Table 6 100 g of alkyd resin of Example 3.1 and 59.19 g of tert-butyl acetoacetate are introduced into a 250 mL reactor equipped with a mechanical stirrer and a distillation column. The 20 reaction medium is heated at 140°C for 3 hours and then maintained under continuous vacuum at 140°C for 1 hour. An amber-colored polymer is obtained. Analysis by1H NMR spectrometry shows the presence of AcAc groups on the polyester obtained. 25 Example 4: Synthesis of a polyester bearing acetoacetate functions (polyester 4) Example 4.1 Alkyd resin 4 – outside the invention Alkyd resin 4 was prepared from the reagents and contents indicated in the table below: 110 Table 7 a) 18.74 g of dipentaerythritol, 78.75 g of pentaerythritol, 26.25 g of lauric acid and 112.50 g of isostearic acid are placed in a 0.5 L reactor equipped with a mechanical stirrer, a 5 distillation column and an argon inlet. The reactor is maintained under an argon atmosphere throughout the synthesis by sparging. The reaction medium is heated at 230°C for 7 hours. The acid number Ia is measured: Ia = 11.30 mg KOH / g. b) 37.50 g of adipic acid and 26.25 g of homophthalic acid are placed in the reactor. Heating is maintained at 230°C for 7 hours, before cooling. 10 The alkyd resin is obtained in the form of a very viscous caramel-colored liquid polymer. The final acid number Ia and hydroxyl number IOHare measured. Ia = 4.5 mg KOH / g IOH = 267 mg KOH / g 15 Example 4.2 Polyester 4 - invention Polyester 4 was prepared from the reagents and contents indicated in the table below: Table 8 114.02 g of alkyd resin of Example 4.1 and 85.88 g of tert-butyl acetoacetate are introduced into a 250 mL reactor equipped with a mechanical stirrer and a distillation column. The 111 reaction medium is heated at 140°C for 4 hours and then maintained under continuous vacuum at 140°C for 1 hour. A very viscous caramel-colored polymer is obtained. Analysis by1H NMR spectrometry shows the presence of AcAc groups on the polyester obtained. 5 Example 5: Synthesis of a polyester bearing acetoacetate functions (polyester 5) Example 5.1 Alkyd resin 5 – outside the invention Alkyd resin 5 was prepared from the reagents and contents indicated in the table below: 10 Table 9 a) 128.04 g of dipentaerythritol, 27.68 g of Pripol 2033, 75.56 g of octanoic acid and 110.8 g of oleic acid are placed in a 0.5 L reactor equipped with a mechanical stirrer, a distillation column and an argon inlet. The reactor is maintained under an argon atmosphere throughout the synthesis by sparging. The reaction medium is heated at 180°C for 5 hours. 15 b) 35.24 g of adipic acid and 22.68 g of homophthalic acid are placed in the reactor. Heating is maintained at 230°C for 8 hours, before cooling. The alkyd resin is obtained in the form of a very viscous caramel-colored liquid polymer. The final acid number Ia and hydroxyl number IOHare measured. 20 Ia = 2.41 mg KOH / g IOH = 232 mg KOH / g Example 5.2 Polyester 5 - invention Polyester 5 was prepared from the reagents and contents indicated in the table below: 112 60.41 g of alkyd resin of Example 5.1 and 39.59 g of tert-butyl acetoacetate are introduced into a 250 mL reactor equipped with a mechanical stirrer and a distillation column. The 5 reaction medium is heated at 140°C for 3 hours and then maintained under continuous vacuum at 140°C for 1 hour. An amber-colored polymer is obtained. Analysis by1H NMR spectrometry shows the presence of AcAc groups on the polyester obtained. 10 Example 6: Synthesis of a polyester bearing acetoacetate functions (polyester 6) Example 6.1 Alkyd resin 6.1 – outside the invention Alkyd resin 6.1 was prepared from the reagents and contents indicated in the table below: 15 200 g of oleyl alcohol, 95.12 g of 1,10-decanediol and 104.88 g of citric acid are placed in a 0.5 L reactor equipped with a mechanical stirrer, a distillation column and an argon inlet. The reaction medium is gradually heated to a temperature of 190°C over 1 hour, and the temperature is then maintained at 190°C for 10 hours, before being raised to 230°C for 7 20 hours. The alkyd resin is obtained in the form of a viscous amber-colored oil. The acid number Ia is measured: Ia = 2.78 mg KOH / g 113 Example 6.2 Alkyd resin 6.2 – outside the invention Alkyd resin 6.2 was prepared from the reagents and contents indicated in the table below: 5 25 g of the alkyd resin from Example 6.1, 14 g of 1-thioglycerol and 2 g of 2-hydroxy-2- methylpropiophenone (sold by Sigma-Aldrich under reference number 405655) are introduced into a 250 mL reactor containing 150 mL of ethyl acetate. The reaction medium is then stirred for 5 minutes under argon, and then irradiated under a UV lamp (100 W, 365 nm) for 4 hours. The reaction medium is then washed twice with NaCl-saturated water. The 10 organic phase is finally dried over MgSO4 and then concentrated under vacuum. A polymer in the form of a viscous yellow oil is obtained. Ia = 2.78 mg KOH / g IOH = 279.5 mg KOH / g 15 Example 6.3 Polyester 6 – invention Polyester 6 was prepared using the following reagents with the indicated masses and mass percentages: 20 20 g of the alkyd resin of Example 6.2 and 15.8 g of tert-butyl acetoacetate are introduced into a 250 mL round-bottomed flask equipped with a mechanical stirrer. The reaction 114 medium is heated at 130°C on an oil bath for 4 hours and then maintained under continuous vacuum at 130°C for 1 hour. A viscous caramel-colored liquid polymer is obtained. Analysis by1H NMR spectrometry shows the presence of AcAc groups on the polyester obtained. 5 Example 7: Preparation of compositions 1A and 1B Composition 1A comprising an alkyd resin outside the invention and composition 1B comprising a polyester of formula (I) according to the invention are prepared using the contents indicated in the table below. The contents are expressed as weight percentages 10 relative to the total weight of the composition. Compositions 1A and 1B are prepared by mixing the ingredients detailed in Table 14, according to the homogenization protocol specified above. 15 Example 8: One-step application of compositions 1A and 1B to the skin Compositions 1A and 1B are applied according to the one-step skin application protocol described previously. The deposits are then evaluated according to the olive oil, sebum and water resistance protocols and the adhesive tape resistance protocol for the formulations on Bioskin. 20 The evaluation results are summarized in the table below 115 Table 15 It can be seen that the application of composition 1B according to the process of the invention allows a significantly improved resistance to olive oil, water and sebum to be obtained relative to the application of composition 1A, and the adhesive tape test is also very effective, 5 thus showing that composition 1B adheres to the substrate. Thus, by virtue of the application of composition 1B according to the process of the invention, deposits are obtained which are resistant to daily chemical attacks (water / sebum / olive oil) and which are highly adhesive. Moreover, the process according to the invention is particularly advantageous from an 10 environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. Example 9: Preparation of compositions 2A and 2B 15 Composition 2A comprising an alkyd resin outside the invention and composition 2B comprising a polyester of formula (I) according to the invention are prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition. 116 Table 16 Compositions 2A and 2B are prepared by mixing the ingredients detailed in Table 16, according to the homogenization protocol specified above. 5 Example 10: One-step application of compositions 2A and 2B to the skin Compositions 2A and 2B are applied according to the one-step skin application protocol described previously. The deposits are then evaluated according to the olive oil resistance protocol and the 10 fragmentation protocol for the formulations on Bioskin. The evaluation results are summarized in the table below: It can be seen that the application of composition 2B according to the process of the invention 15 makes it possible to obtain a significantly improved resistance to olive oil compared to the application of composition 2A, and the fragmentation test is also very effective, thus showing that the film obtained with composition 2B is very elastic. Thus, by virtue of the application of composition 2B according to the process of the invention, oil-resistant (olive oil) and highly elastic (fragmentation) deposits are obtained. 20 Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. 25 Example 11: Preparation of compositions 3A and 3B Composition 3A comprising an alkyd resin outside the invention and composition 3B comprising a polyester of formula (I) according to the invention are prepared using the 117 contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition. 5 Compositions 3A and 3B are prepared by mixing the ingredients detailed in Table 18 in the following order: the polyester of formula (I) bearing acetoacetate functions or the alkyd resin(s) not bearing acetoacetate functions, the pigment, the solvent and the crosslinking agent are homogenized together in a Speedmixer (a mixing device that uses centrifugal force) for 2 minutes at 3500 rpm and at room temperature, and the catalyst is then introduced 10 after the homogenization step. Example 12: One-step application of compositions 3A and 3B to the skin Compositions 3A and 3B are applied according to the one-step skin application protocol described previously. 15 The deposits are then evaluated according to the olive oil, sebum and water resistance protocols and the adhesive tape resistance protocol for the formulations on Bioskin. The evaluation results are summarized in the table below: 118 Table 19 It can be seen that the application of composition 3B according to the process of the invention 5 allows a significantly improved resistance to olive oil, water and sebum to be obtained relative to the application of composition 3A, and the adhesive tape test is also very effective, thus showing that composition 3B adheres to the substrate. Thus, by virtue of the application of composition 3B according to the process of the invention, deposits are obtained which are resistant to daily chemical attacks 10 (water / sebum / olive oil) and which are highly adhesive. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. 15 Example 13: Preparation of compositions 4A and 4B Composition 4A comprising an alkyd resin outside the invention and composition 4B comprising a polyester of formula (I) according to the invention are prepared using the contents indicated in the table below. The contents are expressed as weight percentages 20 relative to the total weight of the composition.

[0004] 119 Compositions 4A and 4B are prepared by mixing the ingredients detailed in Table 20 in the following order: the polyester of formula (I) bearing acetoacetate functions or the alkyd 5 resin(s) not bearing acetoacetate functions, the pigment, the solvent and the crosslinking agent are homogenized together in a Speedmixer (a mixing device that uses centrifugal force) for 2 minutes at 3500 rpm and at room temperature, and the catalyst is then introduced after the homogenization step. 10 Example 14: One-step application of compositions 4A and 4B to the skin Compositions 4A and 4B are applied according to the one-step skin application protocol described previously. The deposits are then evaluated according to the olive oil, sebum and water resistance protocols and the adhesive tape resistance protocol for the formulations on Bioskin. 15 The evaluation results are summarized in the table below: Table 21 120 It can be seen that the application of composition 4B according to the process of the invention allows a significantly improved resistance to olive oil, water and sebum to be obtained relative to the application of composition 4A, and the adhesive tape test is also very effective, thus showing that composition 4B adheres to the substrate. 5 Thus, by virtue of the application of composition 4B according to the process of the invention, deposits are obtained which are resistant to daily chemical attacks (water / sebum / olive oil) and which are highly adhesive. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus 10 the associated water savings, and the low number of steps required to obtain the AcAc polyester. Example 15: Preparation of compositions 5A and 5B Composition 5A comprising an alkyd resin outside the invention and composition 5B 15 comprising a polyester of formula (I) according to the invention are prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition. 20 Compositions 5A and 5B are prepared by mixing the ingredients detailed in Table 22, according to the homogenization protocol specified above. 121 Example 16: One-step application of compositions 5A and 5B to the skin Compositions 5A and 5B are applied according to the one-step skin application protocol described previously. The deposits are then evaluated according to the olive oil, sebum and water resistance 5 protocols and the adhesive tape resistance protocol for the formulations on Bioskin. The evaluation results are summarized in the table below: Table 23 It can be seen that the application of composition 5B according to the process of the invention 10 allows a significantly improved resistance to olive oil, water and sebum to be obtained relative to the application of composition 5A, and the adhesive tape test is also very effective, thus showing that composition 5B adheres to the substrate. Thus, by virtue of the application of composition 5B according to the process of the invention, deposits are obtained which are resistant to daily chemical attacks 15 (water / sebum / olive oil) and which are highly adhesive. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. 20 Example 17: Preparation of compositions 6A and 6B Composition 6A comprising an alkyd resin outside the invention and composition 6B comprising a polyester of formula (I) according to the invention are prepared using the contents indicated in the table below. The contents are expressed as weight percentages 25 relative to the total weight of the composition. 122 Compositions 6A and 6B are prepared by mixing the ingredients detailed in Table 24, 5 according to the homogenization protocol specified above. Example 18: One-step application of compositions 6A and 6B to the skin Compositions 6A and 6B are applied according to the one-step skin application protocol described previously. 10 The deposits are then evaluated according to the olive oil resistance protocol and the fragmentation protocol for the formulations on Bioskin. The evaluation results are summarized in the table below: Table 25 123 It can be seen that the application of composition 6B according to the process of the invention allows a significantly improved resistance to olive oil, water and sebum to be obtained relative to the application of composition 6A, and the adhesive tape test is also very effective, thus showing that composition 6B adheres to the substrate. 5 Thus, by virtue of the application of composition 6B according to the process of the invention, deposits are obtained which are resistant to daily chemical attacks (water / sebum / olive oil) and which are highly adhesive. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus 10 the associated water savings, and the low number of steps required to obtain the AcAc polyester. Example 19: Preparation of compositions 7A and 7B Composition 7A comprising an alkyd resin outside the invention and composition 7B 15 comprising a polyester of formula (I) according to the invention are prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition. 124 Compositions 7A and 7B are prepared by mixing the ingredients detailed in Table 26, according to the homogenization protocol specified above. Example 20: One-step application of compositions 7A and 7B to the skin 5 Compositions 7A and 7B are applied according to the one-step skin application protocol described previously. The deposits are then evaluated according to the olive oil, sebum and water resistance protocols and the adhesive tape resistance protocol for the formulations on Bioskin. The evaluation results are summarized in the table below: 10 Table 27 It can be seen that the application of composition 7B according to the process of the invention allows a significantly improved resistance to olive oil, water and sebum to be obtained 15 relative to the application of composition 7A, and the adhesive tape test is also very effective, thus showing that composition 7B adheres to the substrate. Thus, by virtue of the application of composition 7B according to the process of the invention, deposits are obtained which are resistant to daily chemical attacks (water / sebum / olive oil) and which are highly adhesive. 20 Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. 25 Example 21: Preparation of compositions 8A and 8B Composition 8A comprising an alkyd resin outside the invention and composition 8B comprising a polyester of formula (I) according to the invention are prepared using the 125 contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition. 5 Compositions 8A and 8B are prepared by mixing the ingredients detailed in Table 28, according to the homogenization protocol specified above. Example 22: One-step application of compositions 8A and 8B to the skin Compositions 8A and 8B are applied according to the one-step skin application protocol 10 described previously. The deposits are then evaluated according to the olive oil, sebum and water resistance protocols for the formulations on Bioskin. The evaluation results are summarized in the table below: Table 29 15 It is seen that the application of composition 8B according to the process of the invention allows a significantly improved resistance to olive oil, water and sebum to be obtained relative to the application of composition 8A. 126 Thus, by virtue of the application of composition 8B according to the process of the invention, deposits that are resistant to daily chemical attack (water / sebum / olive oil) are obtained. Moreover, the process according to the invention is particularly advantageous from an 5 environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. Example 23: Preparation of compositions 9A and 9B 10 Composition 9A comprising an alkyd resin outside the invention and composition 9B comprising a polyester of formula (I) according to the invention are prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition. Table 30 15 Compositions 9A and 9B are prepared by mixing the ingredients detailed in Table 30, according to the homogenization protocol specified above. 127 Example 24: Two-step application of compositions 9A and 9B to the skin Compositions 9A and 9B are applied according to the two-step skin application protocol described previously. The deposits are then evaluated according to the sebum and adhesive tape resistance 5 protocols for the formulations on Bioskin. The evaluation results are summarized in the table below: Table 31 10 It can be seen that the application of composition 9B according to the process of the invention allows a significantly improved resistance to sebum to be obtained relative to the application of composition 9A, and the adhesive tape test is also very effective, thus showing that composition 9B adheres to the substrate. Thus, by virtue of the application of composition 9B according to the process of the 15 invention, deposits that are resistant to fatty substances (sebum) and highly adhesive are obtained. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc 20 polyester. Example 25: Preparation of compositions 10A and 10B Composition 10A comprising an alkyd resin outside the invention and composition 10B comprising a polyester of formula (I) according to the invention are prepared using the 25 contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition. 128 Compositions 10A and 10B are prepared by mixing the ingredients detailed in Table 32, according to the homogenization protocol specified above. 5 Example 26: One-step application of compositions 10A and 10B to the skin Compositions 10A and 10B are applied according to the one-step skin application protocol described previously. The deposits are then evaluated according to the olive oil, sebum and water resistance 10 protocols and the adhesive tape resistance protocol for the formulations on Bioskin. The evaluation results are summarized in the table below: Table 33 15 It can be seen that the application of composition 10B according to the process of the invention allows a significantly improved resistance to olive oil, water and sebum to be 129 obtained relative to the application of composition 10A, and the adhesive tape test is also very effective, thus showing that composition 10B adheres to the substrate. Thus, by virtue of the application of composition 10B according to the process of the invention, deposits are obtained which are resistant to daily chemical attacks 5 (water / sebum / olive oil) and which are highly adhesive. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. 10 Example 27: Preparation of compositions 11A and 11B Composition 11A comprising an alkyd resin outside the invention and composition 11B comprising a polyester of formula (I) according to the invention are prepared using the contents indicated in the table below. The contents are expressed as weight percentages 15 relative to the total weight of the composition. Compositions 11A and 11B are prepared by mixing the ingredients detailed in Table 34, according to the homogenization protocol specified above. 20 130 Example 28: One-step application of compositions 11A and 11B to the skin Compositions 11A and 11B are applied according to the one-step skin application protocol described previously. The deposits are then evaluated according to the olive oil, sebum and water resistance 5 protocols and the adhesive tape resistance protocol for the formulations on Bioskin. The evaluation results are summarized in the table below: Table 35 It can be seen that the application of composition 11B according to the process of the 10 invention allows a significantly improved resistance to olive oil, water and sebum to be obtained relative to the application of composition 11A, and the adhesive tape test is also very effective, thus showing that composition 11B adheres to the substrate. Thus, by virtue of the application of composition 11B according to the process of the invention, deposits are obtained which are resistant to daily chemical attacks 15 (water / sebum / olive oil) and which are highly adhesive. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. 20 Example 29: Preparation of compositions 12A1, 12A2, 12B1 and 12B2 Compositions 12A1, 12A2, 12B1 and 12B2 are prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition under consideration. 25 131 Table 36 Compositions 12A1, 12A2, 12B1 and 12B2 are prepared by mixing the ingredients detailed in Table 36, according to the homogenization protocol specified above. 5 Example 30: One-step application of compositions 12A1, 12A2, 12B1 and 12B2 to the skin - Gloss persistence evaluation Compositions 12A1, 12A2, 12B1 and 12B2 and titanium butoxide are applied according to 10 the gloss persistence protocol described previously. The values are expressed as GU (Gloss Units). The evaluation results are summarized in the table below:

[0005] 132 Table 37 It can be seen that the application of compositions 12B1 and 12B2 according to the process of the invention affords a film which has high gloss. It can also be seen that the application 5 of compositions 12B1 and 12B2 according to the process of the invention significantly improves the gloss persistence after attack with water. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc 10 polyester. Example 31: Preparation of compositions 12A3 and 12B3 Compositions 12A3 and 12B3 are prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the 15 composition under consideration. 133 Table 38 Compositions 12A3 and 12B3 are prepared by mixing the ingredients detailed in Table 38, according to the homogenization protocol specified above. 5 Example 32: One-step application of compositions 12A3 and 12B3 to the skin - Gloss persistence evaluation Compositions 12A3 and 12B3 are applied according to the gloss persistence protocol described previously. 10 The values are expressed as GU (Gloss Units). The evaluation results are summarized in the table below: Table 39 It is seen that the application of composition 12B3 according to the process of the invention 15 affords a film which has high gloss. It is also seen that the application of composition 12B3 134 according to the process of the invention affords a significant improvement in the gloss persistence, after attack with water. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus 5 the associated water savings, and the low number of steps required to obtain the AcAc polyester. Example 33: Preparation of composition 13 Composition 13 is prepared using the contents indicated in the table below. The contents are 10 expressed as weight percentages relative to the total weight of the composition. Table 40 Composition 13 is prepared by mixing the ingredients detailed in Table 40, according to the hair dye application protocol specified above. 15 Example 34: One-step hair dyeing application of composition 13 Composition 13 is applied according to the one-step hair application protocol described previously. The evaluation results are summarized in the table below: 20 135 The locks of hair dyed according to the invention have a ΔE value of less than 2 after three shampoo washes. It is thus seen that the application of composition 13 according to the process of the invention allows very good color persistence to be obtained. Moreover, the process according to the invention is particularly advantageous from an 5 environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. Example 35: Preparation of composition 14 10 Composition 14 is prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition. Table 42 Composition 14 is prepared by mixing the ingredients detailed in Table 42, according to the hair dye application protocol specified above. 15 Example 36: One-step hair dyeing application of composition 14 Composition 14 is applied according to the one-step hair application protocol described previously. The evaluation results are summarized in the table below: 136 The locks of hair dyed according to the invention have a ΔE value of 2.19 after three shampoo washes. It is thus seen that the application of composition 14 according to the process of the invention allows very good color persistence to be obtained. 5 Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc polyester. 10 Example 36: Preparation of composition 15 Composition 15 is prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition under consideration. Table 44 15 Composition 15 is prepared by mixing the ingredients detailed in Table 44, according to the hair dye application protocol specified above. Example 37: Two-step hair dyeing application of composition 15 20 Composition 15 is applied according to the two-step hair application protocol described previously. The evaluation results are summarized in the table below: 137 The locks of hair dyed according to the invention have a ΔE value of less than 2 after three shampoo washes. It is thus seen that the application of composition 15 according to the 5 process of the invention allows very good color persistence to be obtained. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the low number of steps required to obtain the AcAc polyester. 10 Example 38: Preparation of composition 16 Composition 16 is prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition under consideration. Table 46 15 138 Composition 16 is prepared by mixing the ingredients detailed in Table 46, according to the hair dye application protocol specified above. Example 39: Two-step hair dyeing application of composition 16 5 Composition 16 is applied according to the two-step hair application protocol described previously. The evaluation results are summarized in the table below: 10 The locks of hair dyed according to the invention have a ΔE value of less than 2 after three shampoo washes. It is thus seen that the application of composition 16 according to the process of the invention allows very good color persistence to be obtained. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the low number of steps required to obtain the 15 AcAc polyester. Example 40: Preparation of composition 17 Composition 17 is prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition under 20 consideration. 139 Table 48 Composition 17 is prepared by mixing the ingredients detailed in Table 48, according to the hair dye application protocol specified above. 5 Example 41: Two-step hair dyeing application of composition 17 Composition 17 is applied according to the two-step hair application protocol described previously. The evaluation results are summarized in the table below: 10 The locks of hair dyed according to the invention have a ΔE value of less than 2 after three shampoo washes. It is thus seen that the application of composition 17 according to the process of the invention allows very good color persistence to be obtained. 15 Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the low number of steps required to obtain the AcAc polyester. Example 42: Preparation of composition 18 20 Composition 18 is prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition under consideration. 140 Table 50 Composition 18 is prepared by mixing the ingredients detailed in Table 50, according to the hair dye application protocol specified above. 5 Example 43: Two-step hair dyeing application of composition 18 Composition 18 is applied according to the two-step hair application protocol described previously. The evaluation results are summarized in the table below: 10 The locks of hair dyed according to the invention have a ΔE value of less than 2 after three shampoo washes. It is thus seen that the application of composition 18 according to the process of the invention allows very good color persistence to be obtained. 15 Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus 141 the associated water savings, and the low number of steps required to obtain the AcAc polyester. Example 44: Preparation of composition 19 5 Composition 19 is prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition under consideration. Table 52 10 Composition 19 is prepared by mixing the ingredients detailed in Table 52, according to the hair dye application protocol specified above. Example 45: Two-step hair dyeing application of composition 19 Composition 19 is applied according to the two-step hair application protocol described 15 previously. The evaluation results are summarized in the table below: 142 The locks of hair dyed according to the invention have a ΔE value of less than 2 after three shampoo washes. It is thus seen that the application of composition 19 according to the process of the invention allows very good color persistence to be obtained. 5 Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the low number of steps required to obtain the AcAc polyester. Example 46: Preparation of composition 20 10 Composition 20 is prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition under consideration. Table 54 15 Composition 20 is prepared by mixing the ingredients detailed in Table 54, according to the hair dye application protocol specified above. 143 Example 47: Three-step hair dyeing application of composition 20 Composition 20 is applied according to the three-step hair application protocol described previously. 5 The evaluation results are summarized in the table below: The locks of hair dyed according to the invention have a ΔE value of less than 2 after three shampoo washes. It is thus seen that the application of composition 20 according to the 10 process of the invention allows very good color persistence to be obtained. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the low number of steps required to obtain the AcAc polyester. 15 Example 48: Preparation of compositions 21A, 21A1, 21A2, 21B, 21B1 and 21B2 Compositions 21A, 21A1, 21A2, 21B, 21B1 and 21B2 are prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition under consideration.

[0006] 144 Table 56 Compositions 21A, 21A1, 21A2, 21B, 21B1 and 21B2 are prepared by mixing the ingredients detailed in Table 56, according to the Steampod protocol specified above. 5 145 Example 49: One-step hair dyeing application of compositions 21A, 21A1, 21A2, 21B, 21B1 and 21B2 Compositions 21A, 21A1, 21A2, 21B, 21B1 and 21B2 are applied according to the Steampod protocol described previously. The evaluation results are summarized in the 5 table below: The locks of hair dyed with compositions 21A and 21B according to the invention have lower ΔE values than the locks of hair dyed with the comparative compositions 21A1, 10 21A2 and 21B1 and 21B2. Thus, the composition according to the invention and the process according to the invention afford a homogeneous colored coating on the hair which shows improved resistance to shampoo washing. Moreover, the process according to the invention is particularly advantageous from an 15 environmental point of view, notably due to the absence of water-based solvents, and thus 146 the associated water savings, and the low number of steps required to obtain the AcAc polyester. Example 50: Preparation of formulas 22A, 22B, 22C, 22D, 22E, 22F, 22G, 22H, 22I and 5 22J Formulas 22A to 22J are prepared using the contents indicated in the table below. The contents are expressed as weight percentages relative to the total weight of the composition under consideration. Table 58 10 Compositions 22A, 22B, 22C, 22D, 22E, 22F, 22G, 22H, 22I and 22J are prepared by mixing the ingredients detailed in Table 58, according to the styling evaluation protocol specified above. Example 51: Hairstyling application of compositions G to Q - Curl evaluation 15 Compositions 22A to 22J are applied according to the hairstyling protocol described previously. The results of the curl evaluations are summarized in the table below: 147 Table 59 It can be seen that the locks treated with formulas 22B, 22D, 22F, and 22H according to the process of the invention make it possible to obtain well-formed and well-defined curls and to significantly improve the shape retention of the curls over time. Notably, the locks treated 5 according to the process of the invention have a lock length after application of formulas 22B, 22D, 22F and 22H which is significantly reduced compared to the length of the locks treated respectively with the comparative formulas 22A, 22C, 22E, 22G, 22I and 22J. Thus, the shape of the curls of the locks treated according to the process of the invention is seen to be clearer and closer together in contrast to the locks treated with the comparative 10 compositions 22A, 22C, 22E, 22G, 22I and 22J. 148 In addition, even after 24 hours, the locks treated with formulas 22B, 22D, 22F and 22H according to the process of the invention have a clearer curl shape and are closer together than the locks treated with the comparative compositions 22A, 22C, 22E and 22G. Furthermore, the locks treated with formulas 22D, 22F and 22H according to the process of 5 the invention lost significantly less curl than the comparative locks treated with formulas 22C, 22E and 22G, respectively. Moreover, the process according to the invention is particularly advantageous from an environmental point of view, notably due to the absence of water-based solvents, and thus the associated water savings, and the low number of steps required to obtain the AcAc 10 polyester.

Claims

149 Claims 1. A process for the treatment, especially for the cosmetic treatment, of keratin materials, comprising the application to said keratin materials, in one step or in several successive steps, of at least: 5 i) at least one polyester of formula (I) below, comprising at least two acetoacetate functions, including the optical or geometrical isomers thereof, and / or solvates thereof, such as hydrates, or a composition containing same: (Z)–[O-C(O)-C(Ra)(Rb)-C(O)-R4]u(I) in which formula (I): 10 - Z denotes a multivalent radical derived: from an alkyd resin (A) obtained by reaction of: - from 10% to 62% by mass of at least one polyol; - from 10% to 62% by mass of at least one polyacid; - from 35% to 60% by mass of at least one fatty alcohol and / or at least one fatty 15 monoacid; and - from 0% to 20% by mass of at least one monocarboxylic acid; the mass percentages being expressed relative to the total weight of the alkyd resin (A); or 20 an alkyd resin (B) obtained by reacting an ethylenically unsaturated alkyd resin (A) with at least one (poly)hydroxy thiol; - u is an integer greater than 2; - R4 represents a linear or branched, saturated or unsaturated C1-C6 monovalent hydrocarbon-based radical, preferably a (C1-C4)alkyl group, in particular methyl or tert- 25 butyl, more preferentially methyl; - Ra and Rb, which may be identical or different, represent a hydrogen atom or a (C1- C4)alkyl group, preferably a hydrogen atom; and ii) optionally at least one crosslinking agent.

2. The treatment process of claim 1, in which (Z) represents a multivalent radical30 comprising from 40 to 6000 carbon atoms, terminated by m radicals -O- and n radicals - C(O)ORz, with: - m being an integer greater than 2, preferably greater than or equal to 10,150 - n being an integer greater than or equal to zero, - Rz being a hydrogen atom or an alkyl group comprising from 4 to 40 atoms, notably from 5 to 32 atoms, and more preferentially from 6 to 24 carbon atoms, said multivalent radical being cyclic or acyclic, branched, saturated or unsaturated, 5 interrupted with several ester radicals -O-C(O)- or -C(O)-O-, and optionally interrupted with one or more non-adjacent sulfur atoms S.

3. The treatment process as claimed of claim 1 or 2, in which the radical(s) - C(O)ORz are chosen from t-butyl esters or oleyl esters, and esters of caprylic acid, 2- ethylhexanoic acid, 4,5-dimethylhexanoic acid, 2-heptylheptanoic acid, 3,5,5- 10 trimethylhexanoic acid, octanoic acid, isooctanoic acid, nonanoic acid, decanoic acid, isononanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid, cerotic acid (hexacosanoic acid), 3- cyclopentylpropionic acid, 3-cyclohexylpropionic acid, cyclohexylacetic acid, 4- cyclohexylbutyric acid, caproleic acid, undecylenic acid, dodecylenic acid, myristoleic acid, 15 palmitoleic acid, oleic acid, linoleic acid, linolenic acid, elaidic acid, gondoic acid or erucic acid.

4. The treatment process as claimed in any one of the preceding claims, comprising the application to said keratin materials, preferably the skin and / or the hair, of at least ii) a crosslinking agent, in particular chosen from polyamine compounds, polythiol 20 compounds, polycarbonyl compounds, polyacrylates, metal alkoxides, amino alkoxysilanes including only one primary and / or secondary amine group, and mixtures thereof, optionally in combination with an amine catalyst, in particular chosen from piperidine, DMAP (dimethylaminopyridine), DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), DABCO (1,4- diazabicyclo[2.2.2]octane), DBN (1,5-diazabicyclo[4.3.0]non-5-ene), more preferentially25 chosen from DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), DABCO (1,4- diazabicyclo[2.2.2]octane), 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); more preferentially, the at least one crosslinking agent is chosen from spermidine, titanium butoxide (Ti(OCH2CH2CH2CH3)4), trimethylolpropane triacrylate, terephthalaldehyde, (3-aminopropyl)triethoxysilane 30 (APTES), polydimethylsiloxanes comprising primary amine groups at the end of chains or on side chains, for instance bis-cetearyl amodimethicone, 4,7,10-trioxa-1,13- tridecanediamine, polydimethylsiloxanes including at least two thiol groups, polyether151 triamines, in particular polyetheramines (or Jeffamine), chitosans (notably poly(D- glucosamine)), and mixtures thereof.

5. The process as claimed in any one of the preceding claims, also comprising the application to said keratin materials, preferably the skin and / or the hair, of at least iv) a 5 cosmetic active agent, the cosmetic active agent(s) iv) preferably being chosen from: a) dyestuffs, in particular chosen from pigments, direct dyes and mixtures thereof, b) active agents for caring for keratin materials, preferably the skin and / or the hair, c) UV-screening agents, and d) mixtures thereof; 10 preferably, the cosmetic active agent(s) iv) are chosen from a) dyestuffs, preferably chosen from pigments, direct dyes and mixtures thereof; more preferentially, the pigment(s) are chosen from carbon black, iron oxides, in particular yellow, red and black iron oxides, and micas coated with iron oxide, triarylmethane pigments, in particular blue and violet triarylmethane pigments, in particular Blue 1 Lake, azo pigments, in particular red azo 15 pigments, more particularly D&C Red 7, an alkali metal salt of lithol red, in particular the calcium salt of lithol red B, and even more preferentially from red iron oxides, yellow iron oxides and azo pigments, in particular red azo pigments, more particularly D&C Red 7.

6. The process as claimed in any one of the preceding claims, also comprising 20 the application to said keratin materials, preferably the skin and / or the hair, of at least v) a fatty substance, in particular at least one oil, in particular chosen from: a) volatile oils, notably chosen from: - hydrocarbon-based oils containing from 8 to 16 carbon atoms, in particular branched C8-C16alkanes, in particular isoalkanes, more particularly isoalkanes (also known as 25 isoparaffins), preferably C13-C16 isoparaffins, isododecane, isodecane, isohexadecane, for example the oils sold under the trade names Isopar or Permethyl, alone or as mixtures, preferably isododecane (also known as 2,2,4,4,6-pentamethylheptane), linear alkanes, in particular C11-C16alkanes, alone or as mixtures, in particular hexane, decane, undecane, tridecane, isoparaffins, in particular n-dodecane (C12) and n-tetradecane (C14), the undecane- 30 tridecane mixture, mixtures of n-undecane (C11) and n-tridecane (C13), and mixtures thereof including mixtures of n-undecane (C11) and n-tridecane (C13), and volatile C5-C12cyclic, non-aromatic alkanes;152 - short-chain esters containing from 3 to 8 carbon atoms in total, in particular ethyl acetate, methyl acetate, propyl acetate or n-butyl acetate; - carbonate hydrocarbon-based oils of structure R’1-O-C(O)-O-R’2 in which R’1 and R’2independently denote a linear, branched or cyclic C4-C8alkyl group, preferably a C4-C85 alkyl group, more preferentially chosen from dibutyl carbonate or dipentyl carbonate; - ether oils of formula R1-O-R2 in which R1 and R2, independently of each other, denote a linear, branched or cyclic C4-C8alkyl group, preferably a C4-C8alkyl group; - silicone oils, in particular comprising from 2 to 7 silicon atoms, and optionally including alkyl or alkoxy groups containing from 1 to 10 carbon atoms, in particular 10 dimethicones of viscosity 5 and 6 cSt, cyclopentadimethylsiloxane, dodecamethylpentasiloxane, cyclohexadimethylsiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, heptamethylhexyltrisiloxane, heptamethyloctyltrisiloxane, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, dodecamethylpentasiloxane, and mixtures 15 thereof; or b) non-volatile oils, in particular chosen from: - non-volatile fluoro oils, in particular chosen from fluorinated polyethers, fluorosilicone oils and fluorosilicones; - non-volatile silicone oils, in particular chosen from non-volatile silicones having the 20 following INCI names: dimethicone, dimethiconol, trimethyl pentaphenyl trisiloxane, tetramethyl tetraphenyl trisiloxane, diphenyl dimethicone, trimethylsiloxyphenyl dimethicone, phenyl trimethicone, diphenylsiloxy phenyl trimethicone; and mixtures thereof; - non-volatile apolar hydrocarbon-based oils, in particular chosen from linear or 25 branched compounds of mineral or synthetic origin: liquid paraffin, squalane, isoeicosane, mixtures of linear, saturated hydrocarbons, more particularly C15-C28 hydrocarbons, in particular mixtures whose INCI names are (C15-C19)Alkane, (C18-C21)Alkane, (C21- C28)Alkane, hydrogenated or non-hydrogenated polybutenes; hydrogenated or non- hydrogenated polyisobutenes, preferably hydrogenated, hydrogenated or non-hydrogenated 30 polydecenes, decene / butene copolymers, butene / isobutene copolymers, and mixtures thereof; - polar non-volatile hydrocarbon-based oils, in particular chosen from:153 i) saturated, unsaturated, linear or branched C10-C26fatty alcohols, preferably monoalcohols; in particular, the C10-C26 alcohols are fatty alcohols, which are preferably branched when they comprise at least 16 carbon atoms; preferably, the fatty alcohol comprises from 10 to 24 carbon atoms, and more preferentially from 12 to 22 carbon atoms, 5 in particular such as lauryl alcohol, isostearyl alcohol, oleyl alcohol, 2-butyloctanol, 2- undecylpentadecanol, 2-hexyldecyl alcohol, isocetyl alcohol, octyldodecanol and mixtures thereof; ii) triglycerides consisting of fatty acid esters of glycerol, in particular whose fatty acids may have chain lengths ranging from C4 to C36, and notably from C18 to C36, these oils 10 possibly being linear or branched, and saturated or unsaturated; including mixtures thereof; iii) linear aliphatic hydrocarbon-based esters of formula R-C(O)-OR’ in which R- C(O)-O- represents a carboxylic acid residue including from 2 to 40 carbon atoms and R’ represents a hydrocarbon-based chain containing from 1 to 40 carbon atoms, aliphatic hydrocarbon-based esters of alkylene glycol, in particular ethylene glycol or propylene 15 glycol, the total number of carbon atoms in particular being at least 10; iv) hydroxylated esters, in particular polyglyceryl-2 triisostearate; v) aromatic esters, in particular tridecyl trimellitate, C12-C15alcohol benzoate, the 2- phenylethyl ester of benzoic acid, and butyloctyl salicylate; vi) linear fatty acid esters with a total carbon number ranging from 35 to 70, in 20 particular pentaerythrityl tetrapelargonate; vii) esters of C24-C28branched fatty acids or fatty alcohols, in particular triisoarachidyl citrate, pentaerythrityl tetraisononanoate, glyceryl triisostearate, glyceryl tris(2- decyltetradecanoate), pentaerythrityl tetraisostearate, polyglyceryl-2 tetraisostearate or pentaerythrityl tetrakis(2-decyltetradecanoate); 25 viii) the polyesters obtained by condensation of dimer and / or trimer of unsaturated fatty acid and of diol, in particular those with the INCI name Dilinoleic Acid / Butanediol Copolymer or Dilinoleic Acid / Propanediol Copolymer; the polyesters obtained by condensation of fatty acid dimer and of diol dimer, in particular dimer dilinoleyl dimer dilinoleate; 30 ix) synthetic ethers containing from 10 to 40 carbon atoms, in particular dicaprylyl ether;154 x) dialkyl carbonates, the two alkyl chains possibly being identical or different, in particular dicaprylyl carbonate; xi) vinylpyrrolidone copolymers, in particular vinylpyrrolidone / 1-hexadecene copolymer; and 5 xii) mixtures thereof; - non-volatile carbonate oils, in particular chosen from the carbonates of formula R8- O-C(O)-O-R9, where R8and R9, which may be identical or different, represent a linear or branched C4-C12, and preferentially C6-C10, alkyl chain; - oils known as non-volatile ether oils of formula R1-O-R2 in which R1 and R2 10 independently denote a linear, branched or cyclic C6-C24alkyl group, preferably a C6-C18alkyl group, and preferably a C8-C12alkyl group; more preferentially, the volatile oil(s) are chosen from C8-C16 alkanes, in particular branched alkanes, preferably isododecane, isodecane and mixtures thereof, and the non- volatile oil(s) are chosen from isononyl isononanoate and 2-octyldodecanol and mixtures 15 thereof.

7. A process for the treatment, notably the cosmetic treatment, of keratin materials, in particular for caring for and / or making up the skin, the lips, the eyelashes and / or the eyebrows and / or for caring for, styling and / or dyeing keratin fibers, preferably the hair, comprising the application to said keratin materials of i) at least one polyester of formula (I) 20 comprising at least two acetoacetate functions as claimed in any one of claims 1 to 3, included in a composition, termed “C1”, comprising i), optionally iv) at least one cosmetic active agent, in particular as claimed in claim 5; preferably, composition “C1” does not comprise ii) a crosslinking agent; or - said polyester of formula (I) being included in a composition, termed “C2”, 25 comprising i), ii) at least one crosslinking agent, in particular as claimed in claim 4, and optionally iv) at least one cosmetic active agent, in particular as claimed in claim 5; preferably, composition “C2” does not comprise iv) a cosmetic active agent; or - said polyester of formula (I) being included in a composition, termed “C3”, comprising i), ii) at least one crosslinking agent, in particular as claimed in claim 4, iv) at 30 least one cosmetic active agent, in particular as claimed in claim 5, and preferably chosen from dyestuffs, preferably pigments,155 it being understood that compositions “C1,” “C2” and / or “C3” may comprise v) one or more fatty substances, in particular at least one oil as claimed in claim 6, which is preferably volatile, more preferentially isododecane.

8. The treatment process as claimed in claim 7, characterized in that it comprises 5 either a single step of applying composition “C2” or composition “C3” to said keratin materials; or two successive steps of applying to said keratin materials two different compositions, preferably composition “C1” followed by a composition termed “C4” comprising: ii) at least one crosslinking agent, in particular as claimed in claim 4, and 10 optionally iv) at least one cosmetic active agent, in particular as claimed in claim 5; preferably, composition ” C4” does not comprise i) at least one polyester of formula (I), optical or geometrical isomers thereof, salts thereof with organic or mineral acids or bases, and / or solvates thereof, such as hydrates, as defined in any one of claims 1 to 3; or three successive steps of applying to said keratin materials three different 15 compositions, preferably composition “C1” then composition “C4” and then a composition termed “C5” comprising: iv) at least one cosmetic active agent, in particular as claimed in claim 5; preferably, composition “C5” does not comprise i) at least one polyester of formula (I), optical or geometrical isomers thereof, salts thereof with organic or mineral acids or bases, and / or solvates thereof, such as hydrates, as defined in any one of claims 1 to 3, and 20 does not comprise ii) at least one crosslinking agent as defined in claim 4.

9. A cosmetic treatment process for dyeing keratin fibers, in particular the hair, and / or for making up keratin materials, notably the skin, comprising the application to said keratin materials of at least: - a composition, termed “C2”, comprising i) at least one polyester of formula (I) 25 comprising at least two acetoacetate functions as claimed in any one of claims 1 to 3, ii) at least one crosslinking agent, in particular as claimed in claim 4, and optionally iv) at least one cosmetic active agent, in particular as claimed in claim 5; preferably, composition “C2” does not comprise iv) a cosmetic active agent; or - a composition, termed “C3”, comprising i) at least one polyester of formula (I) 30 comprising at least two acetoacetate functions as claimed in any one of claims 1 to 3, ii) at least one crosslinking agent, in particular as claimed in claim 4, and iv) at least one cosmetic active agent, in particular as claimed in claim 5;156 it being understood that compositions “C2” or “C3” may comprise v) one or more fatty substances, in particular as claimed in claim 6.

10. A process for the cosmetic treatment of keratin fibers, for styling keratin fibers, preferably the hair, comprising the application to said keratin fibers of at least: 5 - at least one polyester of formula (I) comprising at least two acetoacetate functions as claimed in any one of claims 1 to 3, or a composition, termed “C1”, comprising i) at least one polyester of formula (I) comprising at least two acetoacetate functions, as claimed in any one of claims 1 to 3, and optionally iv) at least one cosmetic active agent, in particular as claimed in claim 5; preferably, composition “C1” does not comprise ii) a crosslinking 10 agent; or - a composition, termed “C2”, comprising i) at least one polyester of formula (I) comprising at least two acetoacetate functions as claimed in any one of claims 1 to 3, ii) at least one crosslinking agent, in particular as claimed in claim 4, and optionally iv) at least one cosmetic active agent, in particular as claimed in claim 5; preferably, composition “C2” 15 does not comprise iv) a cosmetic active agent; or - a composition, termed “C3”, comprising i) at least one polyester of formula (I) comprising at least two acetoacetate functions as claimed in any one of claims 1 to 3, ii) at least one crosslinking agent, in particular as claimed in claim 4, and iv) at least one cosmetic active agent, in particular as claimed in claim 5; 20 it being understood that compositions “C1” or “C2” or “C3” may comprise v) one or more fatty substances, in particular as claimed in claim 6.

11. An alkyd resin (B), characterized in that it is derived from the reaction of an alkyd resin (A) containing ethylenic unsaturations with at least one (poly)hydroxy thiol, said alkyd resin (A) being obtained via: 25 a) a first step by polycondensation of: - 0% to 12% by mass of at least one compound including at least 3 alcohol functions; - 10% to 30% by mass of at least one diol; - 0% to 12% by mass of at least one dicarboxylic acid compound; - 20% to 50% by mass of at least one compound including at least 3 carboxylic acid 30 functions; - 35% to 60% by mass of at least one fatty alcohol; and - 0% to 20% by mass of at least one monocarboxylic acid compound,157 the mass percentages being expressed relative to the total weight of the alkyd resin (A), it being understood that at least one of the dicarboxylic acid compounds and compounds containing at least 3 carboxylic acid functions, and / or at least one of the fatty 5 alcohols, contains at least one ethylenic unsaturation; followed by b) a second step consisting of a thiol-ene reaction of all or part of the ethylenic unsaturations of the alkyd resin (A) obtained on conclusion of step a), with at least one (poly)hydroxy thiol, preferably of formula (F1) below: RD-SH (F1) 10 in which RD represents a linear or branched C2-C10hydrocarbon-based radical substituted with at least one hydroxyl radical, preferably substituted with one or two hydroxyl radicals.

12. A polyester of formula (I) below, comprising at least two acetoacetate functions, including the optical or geometrical isomers thereof, and / or solvates thereof, such 15 as hydrates, or a composition containing same: (Z)–[O-C(O)-C(Ra)(Rb)-C(O)-R4]u (I) in which formula (I): - u is an integer greater than 2; - R4 represents a linear or branched, saturated or unsaturated C1-C6 monovalent20 hydrocarbon-based radical, preferably a (C1-C4)alkyl group, in particular methyl or tert- butyl, more preferentially methyl; - Ra and Rb, which may be identical or different, represent a hydrogen atom or a (C1- C4)alkyl group, preferably a hydrogen atom; and - Z denotes a multivalent radical derived: 25 I) from an alkyd resin (A1) obtained by polycondensation of: - 10% to 62% by mass, preferably 10% to 42% by mass, of at least one polyol; - 10% to 62% by mass, preferably 10% to 42% by mass, of at least one polyacid; and - 35% to 60% by mass of at least one fatty alcohol, at least one of which contains at least one ethylenic unsaturation; 30 relative to the total weight of the alkyd resin (A1); or II) from an alkyd resin (A2) obtained by polycondensation of:158 -10% to 62% by mass of at least one polyol, said at least one polyol being or comprising at least dipentaerythritol; - 10% to 62% by mass of at least one polyacid; and - 35% to 60% by mass of at least one fatty monoacid; 5 relative to the total weight of the alkyd resin (A2); or III) from an alkyd resin (A3) obtained by polycondensation of: -10% to 62% by mass of at least one polyol, said at least one polyol being xylitol or comprising at least xylitol; 10 - 10% to 62% by mass of at least one polyacid; and - 35% to 60% by mass of at least one fatty monoacid; relative to the total weight of the alkyd resin (A3); or: IV) from an alkyd resin (A4) obtained by polycondensation of: 15 -10% to 62% by mass of a mixture of at least two polyols, said mixture not containing any dipentaerythritol or any xylitol; - 10% to 62% by mass of at least one polyacid; and - 35% to 60% by mass of at least one fatty monoacid; relative to the total weight of the alkyd resin (A4); 20 or V) from an alkyd resin (A5) obtained by polycondensation of: -10% to 62% by mass of at least one polyol other than pentaerythritol and xylitol; - 10% to 62% by mass of at least one polyacid; and - 35% to 60% by mass of a mixture of at least two fatty monoacids; 25 relative to the total weight of the alkyd resin (A5); or VI) from an alkyd resin (A6) obtained by polycondensation of: -10% to 62% by mass of a polyol other than dipentaerythritol and xylitol; - 10% to 62% by mass of at least one polyacid; and 30 - 35% to 60% by mass of a fatty monoacid other than oleic acid; relative to the total weight of the alkyd resin (A6); or159 VII) from an alkyd resin (A7) obtained by polycondensation of: - 10% to 62% by mass, preferably 10% to 42% by mass, of at least one polyol; - 10% to 62% by mass, preferably 10% to 42% by mass, of at least one polyacid, at least one of which contains at least one ethylenic unsaturation; and 5 - 35% to 60% by mass of at least one saturated fatty alcohol; relative to the total weight of the alkyd resin (A7).

13. A process for preparing polyester compounds of formula (I) comprising at least two acetoacetate functions as claimed in claim 12, comprising at least one step of reacting all or some of the hydroxyl functions of at least one alkyd resin (A1), (A2), (A3),10 (A4), (A5), (A6) or (A7), preferably via a (trans)esterification reaction with an ester Gp- C(O)-C(Ra)(Rb)-C(O)-R4, in which Gp denotes a leaving group, preferably a hydroxyl radical or a (C1-C4)alkoxy radical, such as methoxy, ethoxy, isobutoxy or t-butoxy, to form esters -O-C(O)-C(Ra)(Rb)-C(O)-R4 with Ra, Rb and R4 being as defined in claim 12.

14. A composition (herein referred as composition “C2”) comprising i) at least 15 one polyester of formula (I) comprising at least two acetoacetate functions, including the optical or geometrical isomers thereof and / or solvates thereof, such as hydrates, as claimed in any one of claims 1 to 3, ii) at least one crosslinking agent, in particular as claimed in claim 4, and optionally iv) at least one cosmetic active agent, in particular as claimed in claim 5; wherein said composition preferably does not comprise iv) a cosmetic active agent; 20 and wherein said composition may also comprise v) one or more fatty substances, preferably at least one oil, in particular as claimed in claim 6.

15. A composition (herein referred as composition “C3”) comprising i) at least one polyester of formula (I) comprising at least two acetoacetate functions, including the optical or geometrical isomers thereof and / or solvates thereof, such as hydrates, as claimed 25 in any one of claims 1 to 3, ii) at least one crosslinking agent, in particular as claimed in claim 4, and iv) at least one cosmetic active agent, in particular as claimed in claim 5; and wherein said composition may also comprise v) one or more fatty substances, preferably at least one oil, in particular as claimed in claim 6.

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