Photocrosslinkable copolyester compositions

Abstract

The present invention relates to a photocrosslinkable composition comprising a photocrosslinkable copolyester and a co-crosslinking agent comprising at least two reactive functional groups for crosslinking, in particular for photocrosslinking. The present invention also relates to a method for photocrosslinking the photocrosslinkable composition, to a crosslinked composition obtained by crosslinking the photocrosslinkable composition, and to the use of said photocrosslinkable composition for the preparation of products by 3D printing.

Description

[0001] DESCRIPTION

[0002] COMPOSITIONS OF PHOTORELINKABLE COPOLYESTERS

[0003] FIELD OF INVENTION

[0004] The present invention relates to photocrosslinkable copolyester compositions, further comprising a cocrossing agent having unsaturated bonds. The present invention also relates to their preparation and use, particularly in crosslinking processes such as 3D printing, and to the corresponding crosslinked copolyesters.

[0005] STATE OF THE ART

[0006] Biodegradable polyesters, such as polylactic acid (PLA), polyglycolic acid (PGA) and their copolymers, poly(glycerol sebacate) (PGS), are now ubiquitous in the preparation of biomaterials useful both as medical biomaterials and as surface coatings.

[0007] Conventionally, PGS are prepared by melt polycondensation of glycerol and a diacid, at high temperature and under reduced pressure, with fairly long reaction times.

[0008] However, with the development of 3D printing application techniques, which require working at near ambient temperature, under atmospheric pressure, and preferably with short reaction times, new materials have been sought whose preparation processes would be compatible with the requirements of 3D printing application, while maintaining satisfactory thermo-mechanical properties.

[0009] Similarly, conventional processes are also not compatible with the integration of temperature-sensitive organic molecules into the biomaterial.

[0010] Thus, photocrosslinkable materials have been developed obtained by copolymerization of glycerol with sebacic acid and unsaturated acids, the unsaturations being able to subsequently be subjected to a photocrosslinking reaction for example under UV irradiation (see in particular WO2019 / 215441 and WO2021 / 078962).

[0011] US 2009 / 011486 A1 describes, in particular, a photocurable composition comprising a photocurable copolyester, specifically a PGS polyester functionalized with acryloyl chloride. In Examples 1 and 2, the PGSA is photocured in the presence of PEG diacrylate and a photoinitiator.

[0012] Other authors have therefore turned to the use of itaconic acid (an unsaturated acid) as a comonomer. This comonomer is particularly interesting because, unlike (meth)acrylic acid derivatives, it is non-toxic and readily bio-sourced, allowing the production of photocrosslinkable polymers usable for a wide range of applications, including biomedical ones, with a relatively low carbon footprint.

[0013] Thus, Rueben et al. (MRS Advances (2018), 3(27), 1551-1556) describe the synthesis of copolymers of glycerol, sebacic acid and itaconic acid, but with particularly long preparation times (24h).

[0014] Patent application CN1144563 also describes copolymers of polyols, aliphatic diacids, and itaconic acid, and in particular copolymers of glycerol, sebacic acid, and itaconic acid. However, the inventors have demonstrated that the polycondensation preparation process of CN1144563 is not reproducible. Indeed, under the described conditions, uncontrolled side reactions (in particular crosslinking reactions) are observed, linked to the reactivity of the α,p-unsaturated double bonds of itaconic acid. These reactions induce heterogeneity in the functional copolymer and increase the viscosity of the resulting product to the point of clumping, rendering it unsuitable for use in applications such as coatings or in 3D printing processes.

[0015] Therefore, there is a need for photocurable copolyester compositions with a simple, reliable, and reproducible preparation process, particularly suited to industrial scale, preventing the occurrence of uncontrolled side reactions. The use of specific crosslinking agents significantly reduces crosslinking times, making photocurable copolyester compositions usable in 3D printing processes, especially at room temperature and atmospheric pressure. The monomers used will preferably be non-toxic and bio-based to limit the carbon footprint of the resulting copolyesters. Furthermore, processing temperatures are generally lower than in conventional processes and are advantageously compatible with high-temperature sensitive organic molecules.

[0016] BRIEF SUMMARY OF THE INVENTION

[0017] Surprisingly, the inventors demonstrated that adding a co-crosslinking agent of general formula (I) during the crosslinking of the photocrosslinkable copolyester does indeed improve the thermomechanical properties of the resulting crosslinked copolyester compared to copolyesters obtained without a co-crosslinking agent. This also allows for increased photocrosslinking rates and the use of preferably non-toxic and bio-based compounds, thus making the process more environmentally friendly.

[0018] The present invention thus relates first to a photocurable composition comprising: - a photocurable copolyester selected from (i) a copolyester whose constituent units are obtained from the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, or (ii) a copolyester whose constituent units are obtained from the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being subsequently functionalized with an acrylic monomer, the acrylic monomer being selected from itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, mesaconic anhydride, (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride, Ci-Ce alkyl esters of (meth)acrylic acid, or a mixture thereof; and

[0019] - a co-crosslinking agent comprising at least two functional groups reactive for crosslinking, in particular for photocrosslinking.

[0020] The present invention also has as its second object a method for photocrosslinking a photocrosslinkable composition according to the invention, comprising a step of UV irradiation of the photocrosslinkable composition.

[0021] The present invention has as its third object a crosslinked composition obtained by crosslinking a photocrosslinkable composition according to the invention.

[0022] The present invention has as its fourth object the use of a photocurable composition according to the invention for the preparation of products by 3D printing.

[0023] DETAILED DESCRIPTION OF THE INVENTION

[0024] For the purposes of the present invention, the term “a” or “an” means “one or more” or “at least one”.

[0025] For the purposes of the present invention, a range of values ​​designated by the expression "between a and b" represents the range of values ​​from greater than strictly a, to less than strictly b (i.e. excluding the bounds a and b), while any range of values ​​designated by the expression "from a to b" represents the range of values ​​from a to b, i.e. including the strict bounds a and b.

[0026] In this description, "approximately" means that the value in question may be 10% lower or higher, including 5%, and in particular 1%, than the stated value. The compounds mentioned in the description may be of fossil origin or bio-based. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also come from the recycling of previously used materials; that is, they may be partially or totally derived from a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes, in particular, monomers, specifically glycerol, dicarboxylic acid, and acrylic monomer.

[0027] OH i The g ilyce - ro il es t t a tnol of f following island formula t te:

[0028] For the purposes of this invention, a "photocrosslinkable" polymer (including a copolyester) is defined as a polymer which, under the influence of light irradiation, and more particularly UV irradiation, undergoes crosslinking reactions, thereby modifying its chemical structure. These are generally radical reactions in the presence of a photoinitiator.

[0029] For the purposes of this invention, "ambient temperature" means a temperature generally between 15°C and 40°C, preferably between 20°C and 30°C, in particular around 25°C.

[0030] By "atmospheric pressure" we mean here a pressure of approximately 1 bar.

[0031] By "aliphatic" we mean a linear, branched and / or cyclic hydrocarbon group, whether saturated or unsaturated but non-aromatic.

[0032] A "divalent aliphatic chain" is understood to mean a linear or branched divalent hydrocarbon group, whether saturated or unsaturated, but non-aromatic. Thus, an aliphatic chain includes linear or branched alkylene (or alkanediyl), alkenylene (or alkeniyl), or alkynylene (alkynediyl) groups. For the purposes of this invention, an "alkanediyl" group is understood to mean a linear or branched saturated divalent hydrocarbon chain, such as, for example, a methylene, ethanediyl, propanediyl, butanediyl, pentanediyl, or hexanediyl group. For the purposes of this invention, an "alkeniyl" group is understood to mean a linear or branched divalent hydrocarbon chain comprising at least one double bond, such as, for example, a vinylene (ethynylene) or propenylene group. For the purposes of this invention, an "alkynediyl" group is defined as a divalent hydrocarbon chain, linear or branched, comprising at least one triple bond.

[0033] A "monovalent aliphatic group" is understood to mean a monovalent linear or branched hydrocarbon group, whether saturated or unsaturated, but non-aromatic. Thus, an aliphatic group encompasses linear or branched alkyl, alkenyl, or alkynyl groups. For the purposes of this invention, an "alkyl group" is understood to mean a monovalent saturated hydrocarbon chain, linear or branched, such as, for example, a methyl, ethyl, propyl, butyl, pentyl, or hexyl group. For the purposes of this invention, an "alkenediyl group" is understood to mean a divalent hydrocarbon chain, linear or branched, comprising at least one double bond, such as, for example, a vinylene (ethenylene) or propenylene group. For the purposes of this invention, an "alkynediyl group" is understood to mean a divalent hydrocarbon chain, linear or branched, comprising at least one triple bond.

[0034] The term "Ci-Cx alkyl group" refers to a monovalent, saturated, linear or branched hydrocarbon chain comprising from 1 to X carbon atoms, preferably from 1 to 4 carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl groups. The term "C2-CY alkenyl group" refers, in the context of this invention, to a monovalent, linear or branched hydrocarbon chain comprising at least one double bond and from 2 to Y carbon atoms. Examples include ethenyl, propenyl, allyl, butenyl, pentenyl, and hexenyl groups.

[0035] As used here, the "C=C double bond ratio" refers to the ratio of C=C double bonds contributed by at least one acrylic derivative or monomer in the polymer, expressed in mmol of double bonds / g of polymer obtained. The C=C double bond ratio is typically measured by carbon-13 nuclear magnetic resonance (NMR). 13 C).

[0036] The C=C double bond ratio can also be obtained indirectly by quantifying the free acrylic derivative or monomer using size-exclusion chromatography (SEC). This measures the amount of acrylic derivative or monomer (or residual). Assuming that the remaining acrylic derivative or monomer has completely reacted, the C=C double bond ratio corresponds to the difference between the amount of acrylic derivative or monomer involved in the reaction (or initial reaction) and the amount of free acrylic derivative or monomer, these amounts being expressed in mmol / g of polymer obtained.

[0037] By "halogen atom" or "halogen," we mean the atoms of fluorine, chlorine, bromine, and iodine.

[0038] By "halide" we mean here the fluoride (F-), bromide (Br), chloride (Cl') and iodide (I')- ions

[0039] For the purposes of this invention, an "alkoxy (Ci-Cx) group" is defined as an (Ci-Cx) alkyl group, as defined above, linked to the rest of the molecule via an oxygen atom. Examples include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, n-pentoxy, and n-hexoxy.

[0040] By "aryl," we mean here an aromatic hydrocarbon group, preferably comprising 6 to 10 carbon atoms, and including one or more fused rings, such as a phenyl or naphthyl group. Advantageously, it is phenyl.

[0041] The term "heteroaryl" here refers to an aromatic group comprising 5 to 10 cyclic atoms, one or more of which are heteroatoms, advantageously 1, 2, 3, or 4, and even more advantageously 1 or 2, such as sulfur, nitrogen, or oxygen atoms, the other cyclic atoms being carbon atoms. Examples of heteroaryl groups include furyl, thienyl, pyrrolyl, pyridinyl, imidazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyrazolyl, oxadiazolyl, thiadiazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, quinolyl, isoquinolyl, quinoxalyl, and indyl.

[0042] An "arylene group" is understood to be a divalent aromatic hydrocarbon group, preferably comprising 6 to 10 carbon atoms, and including one or more fused rings, such as a phenylene or naphthylene group. Advantageously, this refers to phenylene.

[0043] A "substituted arylene group" includes, in particular, an arylene group as defined above substituted by one or more, in particular one or two, substituents selected from an alkyl group in Ci-Ce and an alkoxy group in Ci-Ce.

[0044] A "heteroarylene group" is understood to be a divalent aromatic heterocycle, comprising 5 to 10 ring atoms, one or more of which are heteroatoms, advantageously 1, 2, 3, or 4, and even more advantageously 1 or 2, such as, for example, sulfur, nitrogen, or oxygen atoms, the other ring atoms being carbon atoms. Pyridinylene is an example.

[0045] A "substituted heteroarylene group" includes, in particular, a heteroarylene group as defined above substituted by one or more, in particular one or two, substituents selected from a Ci-Ce alkyl group and a Ci-Ce alkoxy group.

[0046] An "epoxided" unsaturation is a -C=C- motif that is replaced by the o motif

[0047] A "photoinitiator" is understood to be a compound which, when exposed to light, and in particular to UV light, produces a radical which will initiate the photocrosslinking reaction, which is generally radical.

[0048] As used here, a "stabilizing agent" is understood to be a compound that limits (or even eliminates) secondary reactions of the double bond of the itaconate function, such as radical reactions leading to uncontrolled crosslinking of the polymer, or Michael reactions.

[0049] A phenol is understood to be an organic compound containing a phenol functional group:

[0050] , unsubstituted or substituted, notably by one or more substituents chosen from a halogen atom, -NO2, or an alkyl group in the form Ci-Ce, an alkoxy group in the form Ci-Ce, or an NH-alkyl group in the form Ci-Ce. An aniline is understood to be an organic compound containing an aniline functional group: with R n representing H or an alkyl group in Ci-Ce, unsubstituted or substituted, in particular by one or more substituents chosen from a halogen atom, -NO2, or an alkyl group in Ci-Ce, alkoxy in Ci-Ce, NH-alkyl in Ci-Ce.

[0051] 7. Photocrosslinkable composition

[0052] The photocurable composition comprises:

[0053] - a photocrosslinkable copolyester selected from (i) a copolyester whose constituent units are derived from the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, or (ii) a copolyester whose constituent units are derived from the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being further functionalized with an acrylic monomer, the acrylic monomer being selected from itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, mesaconic anhydride, (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride, C1-C6 alkyl esters of (meth)acrylic acid, or a mixture thereof;

[0054] - a co-crosslinking agent comprising at least two reactive functional groups for crosslinking, in particular for photocrosslinking, advantageously each reactive functional group for crosslinking comprising at least one terminal -CR1=CR2R3 group, with R1 representing H or a Ci-Ce alkyl group, the Ci-Ce alkyl group may be unsubstituted or substituted, for example by -O(Ci-Ce alkyl), -COOH, -COO(Ci-Ce alkyl), NR n iR n 2 or NR n iR n 2Rn3 + X',

[0055] R2 representing H or alkyl in Ci-Ce, the alkyl in Ci-Ce is advantageously unsubstituted, and

[0056] R3 represents H, alkyl in Ci-Ce, -COOH, or -COO(alkyl in Ci-Ce); with Rni, R n 2 and R n 3 independently representing H or alkyl in Ci-Ce, and

[0057] X' representing a counterion carrying a negative charge such as a halide, a hydrogen sulfate (HSO4') or a bisulfite (HSOs').

[0058] Photocurable copolyester

[0059] The dicarboxylic acid monomer can be aliphatic, aromatic, or aliphatic / aromatic. The dicarboxylic acid monomer cannot be itaconic acid. An aliphatic / aromatic dicarboxylic acid monomer comprises an aliphatic portion and an aromatic portion. The dicarboxylic acid monomer preferably comprises from 4 to 36 carbon atoms.

[0060] According to preferred embodiments of the invention, the dicarboxylic acid monomer is aliphatic, in particular saturated, especially linear or branched, preferably a (C3-C2o)alkanediyldiacid carboxylic acid, more preferably a (C8-Cis)alkanediyldiacid carboxylic acid. A (C) group x -C y)alkanediyl is a divalent, saturated, linear or branched hydrocarbon group comprising x to y carbon atoms.

[0061] Preferably, the dicarboxylic acid monomer comprises or consists of a compound of formula [HOOC-(CH2)n-COOH], in which n is an integer from 1 to 30, preferably an integer from 1 to 10. Advantageously, this is sebacic acid (n=8).

[0062] The acrylic monomer is preferably chosen from itaconic acid, itaconic anhydride, (meth)acrylic acid, (meth)acrylic anhydride, or a mixture of these, more preferably (meth)acrylic anhydride, itaconic acid and itaconic anhydride, or a mixture of these.

[0063] The photocrosslinkable copolyester advantageously has a C=C double bond ratio greater than or equal to 0.004 mmol / g, preferably greater than or equal to 0.04 mmol / g or 0.1 mmol / g, advantageously greater than or equal to 0.5 mmol / g, even more preferably greater than or equal to 1 mmol / g.

[0064] The photocurable copolyester may also exhibit at least one of the following characteristics:

[0065] • its number-average molar mass (Mn) is greater than or equal to 500 g / mol, in particular greater than or equal to 1000 g / mol;

[0066] • its number-average molar mass (Mn) is less than 10,000 g / mol, in particular less than or equal to 3,500 g / mol, preferably less than or equal to 3,000 g / mol;

[0067] • its dispersity D (Mw / Mn) is less than 10, preferably less than or equal to 8, in particular less than or equal to 6.

[0068] The number-average molar mass (Mn), the mass-average molar mass (Mw), and the dispersity (also called polydispersity, dispersity D, which is the Mw / Mn ratio) can be measured using known methods by SEC analysis, specifically as described below. The residual monomer content and the (1,2,3-triacylglyceride) unit content are measured using known methods by NMR. 1 H, possibly combined with 2D HSQC / HMBC and NMR experiments 13 C, as described later.

[0069] Advantageously, the photocurable composition comprises from 10 to 95%, in particular from 20 to 90%, preferably from 50% to 85% by weight of photocurable copolyester, relative to the total weight of the composition.

[0070] Typically, when the photocrosslinkable copolyester is a copolyester whose constituent units are obtained from the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being subsequently functionalized with an acrylic monomer, it is likely to be obtained by a process comprising the following steps: a) Contacting a copolyester of glycerol and an unfunctionalized dicarboxylic acid monomer with an acrylic monomer selected from itaconic acid, itaconic anhydride, (meth)acrylic acid, the Ci-Ce alkyl esters of (meth)acrylic acid, and mixtures thereof, b) Heating the mixture from step a) in the presence of a stabilizing agent for a time sufficient to form a photocrosslinkable functionalized copolyester, c) Cooling and recovering the photocrosslinkable functionalized copolyester.

[0071] The copolyester of glycerol and a dicarboxylic acid monomer (non-functionalized) can be obtained in particular by implementing the processes described in EP3149067 and EP1448656.

[0072] The copolyester of glycerol and an unfunctionalized dicarboxylic acid monomer advantageously exhibits one or more of the following characteristics:

[0073] - an average number molar mass (Mn) of the non-functionalized copolyester greater than or equal to 500 g / mol, preferably greater than or equal to 1000 g / mol, even more preferably greater than or equal to 1500 g / mol, advantageously greater than or equal to 2000 g / mol;

[0074] - an average number molar mass (Mn) of the non-functionalized copolyester less than or equal to 10,000 g / mol, preferably less than or equal to 3,500 g / mol, preferably less than or equal to 3,000 g / mol;

[0075] - a dispersity D (Mw / Mn) of the non-functionalized copolyester of less than 10, preferably less than or equal to 8;

[0076] - a residual monomer content of less than or equal to 5% by weight of the weight of the non-functionalized copolyester;

[0077] - a rate of (1,2,3-triacylglyceride) units less than or equal to 20 mol% relative to all units of the non-functionalized copolyester;

[0078] - a molar ratio of the unit (1,3-diacylglyceride) to the unit (1,2-diacylglyceride) greater than 1 of the unfunctionalized copolyester.

[0079] The residual monomer content and the (1,2,3-triacylglyceride) unit content are measured using a known method by NMR. 13 C, where appropriate combined with 2D HSQC / HMBC and NMR experiments 13 C, as described later.

[0080] The copolyester of glycerol and a dicarboxylic acid monomer can also be characterized by its free hydroxyl content, or the number of free hydroxyl groups per gram of copolyester. The free hydroxyl content is determined by NMR, typically NMR 13 C, and is expressed in mol / g of copolyester. The hydroxyl number, expressed in mg KOH / g of copolyester, can be measured, for example, using the method described in ASTM E222-23. The ASTM E222-23 method involves acetylating the hydroxyl groups present with acetic anhydride and then titrating with KOH. The hydroxyl number is then easily converted by a person skilled in the art to mmol of free OH / g of copolyester.

[0081] Advantageously, the molar ratio of acrylic monomer / NoH varies from 1:100 to 2:1, notably from 1:1 to 2:1.

[0082] Step (a) of bringing the non-functionalized copolyester into contact with an acrylic monomer, is typically carried out at a temperature between 20°C and 200°C.

[0083] According to some embodiments, the contacting in step a) is carried out in the absence of solvent or diluent.

[0084] Alternatively, in step (a), the unfunctionalized copolyester and the acrylic monomer may be contacted in a solvent, in particular water. Typically, water is added in a mass quantity of 0% to 100%, preferably 5% to 50%, and even more preferably 10% to 40%, relative to the mass of unfunctionalized copolyester and acrylic monomer involved. To promote homogenization of the medium, agitation may be carried out in a known manner. The stabilizing agent may also be added in step (a).

[0085] In step (b), the functionalization reaction involves the esterification of a free alcohol group from the glycerol copolyester and a dicarboxylic acid monomer by the acrylic monomer. Depending on the reaction conditions, transesterification reactions may also occur, but these are generally minor.

[0086] In one variation, the functionalization step is carried out under conditions that allow water to be removed from the reaction medium (or reactor). Removing water as it is formed during functionalization offers several advantages: it improves the reaction yield and accelerates its kinetics. Preferably, the recovered water is recycled as a solvent for the contacting step (a).

[0087] The pressure in the reactor during step (b) may be constant or variable. The functionalization step (b) is preferably conducted at a pressure between 0.0001 and 2 bar, typically less than or equal to 30 mbar, in particular less than or equal to 20 mbar, preferably less than or equal to 10 mbar.

[0088] Any method known to a person skilled in the art can be used to lower the pressure, in particular using a pump (especially a vane pump), a diaphragm pump, a rotary pump, etc. Such an intermediate pressure is less than 1 bar and varies, for example, from 800 mbar to 50 mbar.

[0089] Heating step b) is preferably carried out at a temperature between 20°C and 250°C. The temperature of heating step b) can be variable or constant.

[0090] The temperature is preferably reached by applying an isotherm or a heating ramp. The heating ramp may include one or more plateaus, also called temperature holding periods, and the ramp typically has a slope of between +0.1°C / min and +TC / min.

[0091] In one embodiment, heating step b) is carried out in the presence of a catalyst, in particular at a concentration of 5000 ppm or less, preferably 3000 ppm or less, advantageously 2000 ppm or less, relative to the total mass of unfunctionalized copolyester and committed acrylic monomer. Preferably, the catalyst comprises or is composed of a food-grade catalyst, that is, a catalyst suitable for food contact (for animals and humans) that meets requirements ensuring there is no risk of toxicity induced by this catalyst for the polyester produced. Such a catalyst meets, in particular, the requirements of U.S. standards 21 CFR 175.300, 21 CFR 177.2420, and / or 21 CFR 175.105 in force at the filing date.

[0092] The food-grade catalyst is advantageously tin-based, in particular monobutyltin oxide marketed under the name FASCAT 9100 by the company PMC Organometallix.

[0093] Advantageously, the heating in step b) is carried out for 30 minutes to 12 hours, preferably for 1 hour to 5 hours.

[0094] Step c) of cooling is carried out in a manner known to a person skilled in the art.

[0095] Alternatively, when the photocrosslinkable copolyester is a copolyester whose constituent units are obtained from the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, it is likely to be obtained by a process comprising a polycondensation step of glycerol with a dicarboxylic acid monomer and at least one acrylic monomer as defined herein.

[0096] The acrylic monomer can be added at the same time as the glycerol and the dicarboxylic acid monomer, or in a later step.

[0097] Typically, the process comprises: a') a step of contacting the glycerol with the dicarboxylic acid monomer and at least one acrylic monomer, and the stabilizing agent, and b') a polycondensation step under reduced pressure, the pressure typically being less than or equal to 30 mbar, in particular less than or equal to 20 mbar, preferably less than or equal to 10 mbar, and preferably at a temperature between 110°C and 200°C, preferably between 120°C and 180°C, in particular at 130°C.

[0098] According to another embodiment, the process comprises: a) a step of contacting glycerol with dicarboxylic acid monomer, b) a first polycondensation step of glycerol with the dicarboxylic acid monomer to obtain a mixture comprising poly(glycerol dicarboxylate), at a pressure of between 1 and 2 bar, c) a step of contacting the mixture comprising poly(glycerol dicarboxylate) with at least one acrylic monomer and the stabilizing agent, and d) a second polycondensation step in the presence of the stabilizing agent under reduced pressure, the pressure being typically less than or equal to 30 mbar, in particular less than or equal to 20 mbar, preferably less than or equal to 10 mbar, to form the photocrosslinkable copolyester.

[0099] The polycondensation step (d) is preferably carried out at a temperature between 50°C and 250°C, preferably between 100°C and 200°C, and in particular between 120°C and 190°C. The target temperature for the polycondensation step (d) may be between 110°C and 200°C, preferably between 120°C and 180°C. The temperature is preferably reached by applying an isotherm or a heating ramp. The heating ramp may include one or more plateaus, also called temperature holding periods, and the ramp typically has a slope of between +0.1°C / min and +1°C / min.

[0100] Working under reduced pressure during the polycondensation steps does indeed improve the efficiency and kinetics of the corresponding polycondensation step.

[0101] Steps (a') and (a”) of contacting the glycerol with the dicarboxylic acid monomer and possibly at least one acrylic monomer, are typically carried out at a temperature between 20°C and 100°C.

[0102] In step (a') or (a”), the glycerol and dicarboxylic acid monomers can be brought into contact with water. Adding water to the monomer mixture homogenizes the mixture and thus reduces its overall viscosity. To promote this homogenization, stirring can be carried out in a known manner.

[0103] According to these variants, water is added to the monomers in a quantity by mass of between 0% and 100% by mass relative to the mass of the monomers involved, preferably ranging from 5% to 50% by mass relative to the mass of the monomers involved, preferably still ranging from 10% to 25% by mass relative to the mass of the monomers involved.

[0104] According to other particularly preferred variants, the contacting of the monomers is carried out by introducing the dicarboxylic acid monomer - and possibly at least one acrylic monomer - into a mixture comprising glycerol and water, improving the homogenization of the reaction mixture after the addition of the dicarboxylic acid monomer and possibly at least one acrylic monomer.

[0105] According to one variant, step (c) of contacting the mixture comprising poly(glycerol dicarboxylate) with at least one acrylic monomer includes adding at least one acrylic monomer, and optionally the stabilizing agent, to the mixture heated to a temperature between 50°C and 250°C, preferably between 100°C and 200°C, in particular between 120°C and 190°C. Preferably, during the contacting step (c), the temperature can vary from room temperature to 130°C. Preferably, the stabilizing agent does not react with the double bond of the derivative or the acrylic monomer in significant yields, or reacts reversibly. For example, the stabilizing agent may undergo a reversible Michael addition reaction. It is therefore a nucleophilic compound that is relatively unreactive with respect to the crosslinking agent, such as a phenol or aniline.

[0106] Advantageously, the stabilizing agent is a compound with the general formula: in which

[0107] Z represents O or NR q with R q representing H or alkyl in Ci-Ce,

[0108] R xi represents H, -CO-aryl or -CO-heteroaryl,

[0109] RX2 independently represents H, halogen, -NO2, -OH, alkoxy in Ci-Ce, -COOH, -COO- alkyl in Ci-Ce, NH-alkyl in Ci-Ce, -SR s , or alkyl in Ci-Ce optionally substituted by ORs or SRs,

[0110] R s independently represents an alkyl in Ci-Cs and p is an integer from 1 to 4, preferably 1 or 2.

[0111] Preferably, p is 1 or 2, and R X 2 independently represents H, -OH, -COOH, alkyl in Ci-Ce optionally substituted by an alkoxy in Ci-Ce or SRs in which Rs is as defined above.

[0112] Advantageously, R xi represents H or -CO-phenyl.

[0113] The stabilizing agent can be used alone or in a mixture.

[0114] Typically, these include aniline, phenol, methoxyphenol (especially 4-methoxyphenol or guaiacol), syringol, 4,6-bis(octylthiomethyl)-o-cresol and / or 2-hydroxy-4-methoxybenzophenone.

[0115] The quantity of stabilizing agent introduced is advantageously between 0.01% and 5% by mass relative to the total mass of the monomers and possibly the acrylic monomer, preferably between 0.1% and 2%, preferably between 0.5% and 1.6%.

[0116] Preferably, the molar ratio of acrylic monomer / dicarboxylic acid monomer varies from 1 / 99 to 99 / 1, preferably from 10 / 90 to 90 / 10, advantageously from 20 / 80 to 80 / 20.

[0117] Co-crosslinking agent

[0118] The co-crosslinking agent comprises at least two functional groups reactive for crosslinking, particularly for photocrosslinking. The co-crosslinking agent may comprise more than two functional groups reactive for crosslinking. In particular, it comprises two to four functional groups reactive for crosslinking, particularly for photocrosslinking.

[0119] These reactive functional groups may be identical or different from each other, as long as they meet the definitions given here. Advantageously, the reactive functional groups are identical to each other.

[0120] Each reactive functional group for crosslinking, also referred to as G hereafter, advantageously comprises at least one terminal group -CR1=CR2R3, where R1 represents H or alkyl in Ci-Ce. The alkyl group in Ci-Ce may be unsubstituted or substituted, for example, by -O(alkyl in Ci-Ce), -COOH, -COO(alkyl in Ci-Ce), NR n iR n 2 or NR n iR n 2Rn3 + X',

[0121] R2 representing H or alkyl in Ci-Ce, the alkyl in Ci-Ce is advantageously unsubstituted, and

[0122] R3 representing H, -alkyl in Ci-Ce, -COOH, or -COO(alkyl in Ci-Ce); with Rni, R n 2 and R n 3 independently representing H or an alkyl group in Ci-Ce, and

[0123] X' representing a counterion carrying a negative charge such as a halide, a hydrogen sulfate (HSO4') or a bisulfite (HSOs').

[0124] Advantageously, R1 represents H or an unsubstituted Ci-Ce alkyl group, or a Ci-Ce alkyl group substituted with -COOH and / or -COO(Ci-Ce alkyl). In particular, R1 represents H; CH2-COOH; or an unsubstituted Ci-Ce alkyl group. Preferably, R1 represents H or -CH3.

[0125] Advantageously, R2 represents H or -CH3.

[0126] Advantageously, R3 represents H or -COOH or -COO(alkyl in Ci-Ce), preferably H or -COOH.

[0127] The functional grouping G advantageously responds to the following formula (I): -C(O)-CR1=CR2R3 (I) with R1, R2 and R3 being as defined previously.

[0128] These functional groups G can be supported by any group A comprising at least three carbon atoms. The group A can be aliphatic, aromatic, or comprise both aliphatic and aromatic parts.

[0129] Advantageously, group A includes carbon and hydrogen atoms, but also heteroatoms, in particular oxygen, nitrogen and sulfur atoms, more advantageously oxygen and nitrogen or oxygen.

[0130] Advantageously A does not understand the following reason:

[0131] In particular, group A advantageously comprises at least two identical F functions chosen from among the functions comprising -O-, -NH-, -NR- a -, -S-, -S(O)-, -S(O)2-. R a can be any substituent such as, for example, an alkyl in Ci-Ce. In particular, A can be derived from one or more polyols.

[0132] A polyol can be an alkane diol, an alkane triol, an alkane tetraol, or a chain of units derived from a diol or triol, such as a poly(alkane diol) or a poly(alkane triol). In polymers, the number of repeating units advantageously varies from 2 to 6, and more advantageously from 2 to 4. The alkane can be linear or branched and advantageously comprises from 2 to 6 carbon atoms. Examples include polyethylene glycols, ethylene glycol, propane diol, and propane triol.

[0133] Respectively, group A can be a derivative meeting the definitions given previously for the polyol, but in which the -OH function is respectively replaced by a function including -NH-, -NR- a -, -S-, -S(O)- or -S(O)2-.

[0134] Group A may comprise at least two linear or branched, saturated or unsaturated, divalent aliphatic chains, each comprising at least two terminal F groups. One terminal F group is subsequently linked to the functional group G (thus forming a group designated -F'-G), and the other terminal F group is linked to any spacer E that allows the divalent aliphatic chains to be joined together. Each aliphatic chain advantageously comprises from 2 to 6 carbon atoms. In particular, Group A may comprise at least two alkane polyol derivatives, each substituted at one hydroxyl group by any spacer E that allows them to be linked and comprising a hydroxyl group that allows bonding to the functional group G. Any other hydroxyl groups are advantageously free.

[0135] Group A may comprise at least two polyethylene glycols, each substituted at a terminal hydroxyl function by any spacer E allowing the polyethylene glycols to be linked together and comprising a terminal hydroxyl function allowing a bond to the functional group G.

[0136] The co-crosslinking agent then advantageously corresponds to the following formula (II): G-F'-aliphatic chain-F'-E-F'-aliphatic chain-F'-G (II) where each G independently represents -C(O)-CR1=CR2R3 with R1, R2, and R3 being as defined previously; the aliphatic chain is as defined previously; E is any spacer; each F' is chosen from -O-, -NH-, -NR- a -, -S, -S(O)-, -S(O)2-, R a being such as defined previously, advantageously F' is -O- ; or to the following formula (III):

[0137] G-[O-CH2CH2]nOEO-[CH2CH2O] m-G (III) with n and m independently representing an integer from 1 to 4; where each G independently represents -C(O)-CR1=CR2R3 with R1, R2 and R3 being as defined previously;

[0138] E is any spacer;

[0139] F' is chosen from -O-, -NH-, -NR a -, -S, -S(O)-, -S(O)2-, R a being such as defined previously, advantageously F' is -O-.

[0140] The spacer E can be aliphatic, aromatic, or comprise both aliphatic and aromatic groups.

[0141] The spacer E may be a linear or branched, saturated or unsaturated, divalent aliphatic chain, with one or more unsaturations that may be epoxidized, of 1 to 24 carbon atoms, advantageously of 1 to 12 carbon atoms, wherein one or more, in particular 1 to 4 methylene units (preferably non-adjacent), are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, -NH-C(O)-, -N(Ci-C6 alkyl)-C(O)-, -C(O)-NH-, -C(O)-N(Ci-C6 alkyl)-, -S-, -S(O)-, -S(O)2-, -NH-, -N(Ci-C6 alkyl)-, a substituted or unsubstituted arylene group, or a substituted heteroarylene group. unsubstituted; said aliphatic chain being optionally substituted, for example by one or more, preferably 1 to 2, -OH or -O- alkyl substituents in Ci-Ce.

[0142] The spacer E may advantageously be a saturated, linear or branched, divalent aliphatic chain of 1 to 12 carbon atoms, in which one or more, in particular one to four non-adjacent methylene units, are optionally replaced by -NH-C(O)-, -N(Ci-C6 alkyl)-C(O)-, -C(O)-NH-, -C(O)-N(Ci-Ce alkyl)-, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group; said aliphatic chain being optionally substituted by one or more, preferably one to two, -OH or -O-Ci-Ce alkyl substituents. The co-crosslinking agent may, for example, be selected from the group consisting of the following compounds: independently representing an integer ranging from 1 to 4, , and their mixtures.

[0143] Group A can include 3 or 4 identical F functions, where each heteroatom originating from the function in question is:

[0144] - linked on one side to a spacer Ei, the spacer Ei is itself linked to the other two, respectively three other, functions F;

[0145] - intended to be linked on the other hand to the functional group G, this link to the functional group G can be direct or via a spacer E2, or to another substitute B; at least two functions F are intended to be linked directly or via the spacer E2 to the functional group G.

[0146] In particular, group A can be derived from a polyol, the polyol being a triol or a tetraol, in which each oxygen atom from the hydroxyl function is bonded:

[0147] - on the one hand to a spacer E1 itself linked to the other two, respectively three other, oxygen atoms from the hydroxyl function;

[0148] - on the other hand, to a hydrogen atom (which will then be substituted by a functional group G to form -F'-G), to a spacer E2, or to a substituent B; at least two oxygen atoms from the hydroxyl group are intended to be bonded directly or via the spacer E2 to the functional group G. Advantageously, each heteroatom from the group in question is:

[0149] - linked on one hand to a spacer Ei itself linked to the other two, respectively three other, functions;

[0150] - intended to be linked on the other hand to the functional group G, this link to the functional group G being able to be direct or via a spacer E2.

[0151] Advantageously, each oxygen atom from the hydroxyl group is bonded:

[0152] - on the one hand to a spacer E1 itself linked to the other two, respectively three other, oxygen atoms from the hydroxyl function of the triol, respectively tetraol;

[0153] - intended to be linked on the other hand to the functional group G, this link to the functional group G being able to be direct or via a spacer E2.

[0154] In other words, group A comprises a spacer E1 substituted by three or four F functions, advantageously by three or four hydroxyl functions. At least two of these F functions, advantageously each of these F functions, are then independently substituted directly by the functional group G or by an -E2-G group. The remaining functions, advantageously hydroxyl, are substituted by at least one substituent B.

[0155] The co-crosslinking agent then responds advantageously to the following formula (IV): where each G independently represents -C(O)-CR1=CR2R3 with R1, R2 and R3 being as defined previously;

[0156] F' is chosen from -O-, -NH-, -NR a -, -S, -S(O)-, -S(O)2-, R agiven that each F' is as defined previously, advantageously each F' is identical, advantageously F' is -O-, E1 is as defined previously and subsequently, each E2 is independently as defined previously and subsequently,

[0157] I is an integer with a value of 0 or 1, j is an integer with a value of 0 or 1, and X represents -B or -(E2)kG with B as defined previously and subsequently, k is an integer with a value of 0 or 1, E2 is independently as defined previously and subsequently, G independently represents -C(O)-CR1=CR2R3 with R1, R2 and R3 being as defined previously, or to the following formula (V): where each G independently represents -C(O)-CR1=CR2R3 with R1, R2 and R3 being as defined previously;

[0158] F' is chosen from -O-, -NH-, -NR a -, -S, -S(O)-, -S(O)2-, R a given that each F' is as defined previously, advantageously each F' is identical, advantageously F' is -O-,

[0159] Ei is as defined previously and subsequently, each E2 is independently as defined previously and subsequently,

[0160] I is an integer with a value of 0 or 1, j is an integer with a value of 0 or 1,

[0161] Y and Z each represent, independently of each other, -B or -(E2)kG with B as defined previously and thereafter, k is an integer equal to 0 or 1, E2 is independently as defined previously and thereafter, G independently represents -C(O)-CR1=CR2R3 with R1, R2 and R3 being as defined previously.

[0162] Each G can be identical or different as long as it meets the definitions given above. Preferably, each G is identical.

[0163] The spacer E1 can be aliphatic, aromatic, or comprise both aliphatic and aromatic groups.

[0164] The spacer E1 is advantageously a linear or branched tri- or tetra-valent aliphatic chain, saturated or unsaturated, of 1 to 12 carbon atoms, advantageously of 1 to 6 carbon atoms.

[0165] The spacer E2, when present, advantageously represents a linear or branched, saturated or unsaturated, divalent aliphatic chain, with one or more unsaturations that may be epoxidized, of 1 to 30 carbon atoms, wherein one or more, in particular 1 to 4 methylene units (preferably non-adjacent), are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, -NH-C(O)-, -N(Ci-C6 alkyl)-C(O)-, -C(O)-NH-, -C(O)-N(Ci-Ce alkyl)-, -S-, -S(O)-, -S(O)2-, -NH-, -N(Ci-Ce alkyl)-, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, said aliphatic chain being optionally substituted.

[0166] The spacer E2 more advantageously represents a linear or branched, saturated or unsaturated divalent aliphatic chain, one or more unsaturations which may be epoxidized, of 1 to 30 carbon atoms, in which 1 or more, in particular 1 to 4 methylene units (preferably non-adjacent) are optionally replaced by -C(O)-, -O-, said aliphatic chain being optionally substituted.

[0167] The aliphatic chain can be substituted by one or more, preferably 1 to 4, substituents chosen from -OH, a C1-C15 alkyl, a C2-C15 alkenyl, the alkyl or alkenyl radicals themselves being able to be substituted by one or more, preferably 1 to 4, substituents chosen from -OH, -OG, G being a functional group as described above.

[0168] The E2 spacer can advantageously be derived from a vegetable oil.

[0169] Advantageously, the methylene unit of the aliphatic chain of E2 linked to the F function carried by the spacer E1 is substituted by -C(O)-. In other words, E2 is advantageously linked to the F function carried by E1 by a -C(O)- unit.

[0170] Substituent B is advantageously an aliphatic, aromatic group, or comprises aliphatic and aromatic groups.

[0171] Advantageously, B is a linear or branched monovalent aliphatic group, saturated or unsaturated, one or more unsaturations which may be epoxidized, of 1 to 30 carbon atoms, in which 1 or more, in particular 1 to 4 methylene units (preferably non-adjacent) are optionally replaced by -0(0)-, -O-, -0-0(0)-, -C(0)-0-, -NH- 0(0)-, -N(Ci-C6 alkyl)-C(O)-, -C(O)-NH-, -C(O)-N(Ci-C6 alkyl)-, -S-, -S(0)-, -S(0)2-, -NH-, -N(Ci-Ce alkyl)-, a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group; said aliphatic group being optionally substituted.

[0172] More advantageously, B is a linear or branched monovalent aliphatic group, saturated or unsaturated, one or more unsaturations being able to be epoxidized, of 1 to 30 carbon atoms, in which 1 or more, in particular 1 to 4 methylene units (preferably non-adjacent) are optionally replaced by -C(O)-, -O-, said aliphatic group being optionally substituted.

[0173] The aliphatic group may be substituted by one or more, preferably 1 to 4, substituents chosen from -OH, a C1-C15 alkyl, a C2-C15 alkenyl, the alkyl or alkenyl radicals themselves being able to be substituted by one or more, preferably 1 to 4, substituents chosen from -OH.

[0174] B can advantageously be derived from a vegetable oil. Advantageously, the methylene unit of the aliphatic chain of B linked to the function F carried by the spacer E1 is substituted by -C(O)-. In other words, B is advantageously linked to the function F carried by E1 by a -C(O)- unit.

[0175] Thus, the co-crosslinking agent can correspond to one of the formulas (IV) and (V) above where: each G independently represents -C(O)-CR1=CR2R3 with R1, R2, and R3 being as defined above; each F' is identical and is chosen from -O-, -NH-, -NR a -, -S-, -S(O)-, -S(O)2-, R a being any substituent such as an alkyl in Ci-Ce, advantageously F' is -O-;

[0176] Ei is any spacer, advantageously a linear or branched tri- or tetra-valent aliphatic chain, saturated or unsaturated, of 1 to 12 carbon atoms, advantageously of 1 to 6 carbon atoms; Each E2 is independently any spacer, advantageously a linear or branched, saturated or unsaturated, divalent aliphatic chain, one or more unsaturations which may be epoxidized, of 1 to 30 carbon atoms, wherein one or more, in particular 1 to 4 methylene units, preferably non-adjacent, are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, -NH-C(O)-, -N(Ci-C6 alkyl)-C(O)-, -C(O)-NH-, -C(O)-N(Ci-Ce alkyl)-, -S-, -S(O)-, -S(O)2-, -NH-, -N(Ci-Ce alkyl)-, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, said aliphatic chain being optionally substituted;

[0177] I is an integer with a value of 0 or 1; j is an integer with a value of 0 or 1;

[0178] X, Y and Z each represent, independently of each other, -B or -(E2)kG with B any substituent, k is an integer equal to 0 or 1, E2 any spacer, G independently represents -C(O)-CR1=CR2R3 with R1, R2 and R3 being as defined above; B advantageously represents a linear or branched monovalent aliphatic group, saturated or unsaturated, one or more unsaturations which may be epoxidized, of 1 to 30 carbon atoms, in which 1 or more, in particular 1 to 4 methylene units, preferably non-adjacent, are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, -NH- 0(0)-, -N(Ci-C6 alkyl)-C(O)-, -C(O)-NH-, -C(O)-N(Ci-C6 alkyl)-, -S-, -S(O)-, -S(O)2-, -NH-, -N(Ci-Ce alkyl)-, a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group, said aliphatic group being optionally substituted. In particular, the co-crosslinking agent corresponds to the following formula (VI):

[0179] Where each G independently represents -C(O)-CR1=CR2R3 with R1, R2 and 3 being as defined previously; F' is chosen from -O-, -NH-, -NR a -, -S, -S(O)-, -S(O)2-, R a being as defined previously, advantageously -O-.

[0180] In particular, the co-crosslinking agent is the compound of formula (VII) following

[0181] The co-crosslinking agent may also advantageously be derived from a vegetable oil triglyceride, possibly epoxidized, functionalized by grafting at least two G functional groups, such as for example the compound of formula (VIII) following: Thus, the co-crosslinking agent is advantageously chosen from the group consisting of compounds an integer ranging from 1 to 4, Typically, the co-crosslinking agent is present at a concentration ranging from 5% to 90%, particularly from 10% to 80%, preferably from 15% to 50%, by mass relative to the total mass of the composition. Additives

[0182] The composition may further comprise a photoinitiator, advantageously at a content ranging from 0.05% to 5%, preferably from 0.1% to 4%, in particular from 0.2% to 3%, by mass relative to the total mass of the composition.

[0183] Photoinitiators suitable for photocrosslinking are well known to those skilled in the art. They can be of type I or type II. Type I photoinitiators are single-molecular systems that proceed by homolytic cleavage of a C-C bond, specifically by Norrish I cleavage. The molecules involved are generally aromatic ketones which, after light absorption, undergo homolytic cleavage of the bond at the α position relative to the carbonyl group (Norrish I cleavage) from their excited triplet state, leading to the formation of two free radicals capable of initiating a radical polymerization reaction (see, in particular, Ley et al. 14). ème International Francophone Symposium on Optical Methods and Techniques for Industry / 16th French Congress of the FLUVISU / SFO Club (CMOI-FLUVISU 2015), CMOI Club - French Optical Society, Nov 2015, Pleumeur-Bodou, France, pp.124-129. hal-01583762).

[0184] Type I photoinitiators are, in particular, any precursor of the benzoyl radical:

[0185] Type I

[0186] Type II photoinitiators are, in particular, any precursor of a cetyl radical (inert) and with a radical precursor (an amine).

[0187] Type II Cetyl radical (inert) ir vk> arri»!'

[0188] The photoinitiators will be chosen in particular from the family of type I photoinitiators.

[0189] Examples include 2,4,6-Trimethylbenzoyldi-Phenylphosphinate (TPO L), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and 1-Hydroxycyclohexyl phenyl ketone (HCHPK). Advantageously, the composition further comprises a compound M, liquid at room temperature, comprising a radical polymerizable function, this radical polymerizable function preferably being an acrylic function, typically of the formula representing H or a C(O)ORf group, and with Rf representing H, or a C1-C10 alkyl group, the C1-C10 alkyl group being substituted or unsubstituted by one or more, preferably one or two, C1-C2 alkoxy, C2-C6 alkenyl, or NR group(s) P IR P 2 or NR P IR P 2R P 3 + X', with R Pi , R P 2 and R P3 independently representing H or an alkyl group in Ci-Ce and X' representing a counter-ion carrying a negative charge such as a halide, a hydrogen sulfate (HSC r) or a bisulfite (HSO ), the acrylic group being linked to the rest of the molecule by the i bond.

[0190] Advantageously, the compound M further comprises one or more advantageously chosen functions from:

[0191] • An amine function, in particular a -NR group n iR n 2 or -NR n iR n 2Rn3 + X with R ni , Rn2 and Rn3 independently representing H or an alkyl group in Ci-Ce and X' representing a counter-ion carrying a negative charge such as a halide, a hydrogen sulfate (HSC r) or a bisulfite (HSCh"),

[0192] • A carboxylic acid function or a carboxylic ester function.

[0193] Preferably the molar mass of compound M is less than or equal to 300 g / mol, in particular less than or equal to 250 g / mol.

[0194] Advantageously, the monomer M is an unsaturated alpha-beta ester optionally substituted by a second ester function, such as itaconic acid, itaconic anhydride, (meth)acrylic acid, or a derivative thereof, or mixtures thereof.

[0195] Advantageously, compound M is a compound of formula (XI), (XII), (XIII) or (XIV):

[0196] (XIV), in which:

[0197] R represents H or a C1-C10 alkyl group, preferably H or a methyl group; Rf and Rf independently represent H, a C1-C10 alkyl group, the C1-C10 alkyl group being unsubstituted or substituted by one or more, preferably one or two, C1-C10 alkoxy, C2-C6 alkenyl, or NR group(s). n iR n 2 or NR n iR n 2Rn3 + X-, with R n i, Rn2 and R n3 independently representing H or an alkyl group in Ci-Ce and X- representing a counterion carrying a negative charge such as a halide, a hydrogen sulfate (HSOT) or a bisulfite (HSCh').

[0198] Preferably, compound M is a C1-C10 alkyl diester of itaconic acid or a C1-C10 alkyl ester of methacrylic acid. Examples of compound M include dimethylitaconate, butyl methacrylate, and 2-ethylhexyl methacrylate.

[0199] Typically, compound M is present at a content ranging from 1% to 90%, especially from 10% to 80%, preferably from 30% to 70%, by mass relative to the total mass of the composition.

[0200] According to some embodiments, the composition does not include any additives, in particular no conventional additives.

[0201] According to embodiments, the photocurable composition may further comprise one or more conventional additives in the art, such as fillers.

[0202] The composition may also include an additive chosen from the group consisting of colorants, stabilizers, organic fillers and mixtures thereof, advantageously at a content ranging from 1% to 50% by mass relative to the total mass of the composition.

[0203] Dyes and organic fillers are well known to those skilled in the art. Stabilizing agents are typically as defined previously.

[0204] In some embodiments, the composition may further include a molecule of interest

[0205] The photocurable composition can be obtained by simply mixing the different components, preferably at room temperature to avoid any unwanted or secondary reactions. In particular, the photoinitiator is preferably added to the photocurable composition at room temperature. This prevents any undesirable crosslinking reactions.

[0206] 2. Photocrosslinking process

[0207] The invention also relates to a method of photocrosslinking the photocrosslinkable composition described herein, comprising a step of UV irradiation of the photocrosslinkable composition or the photocrosslinkable copolyester, preferably in the presence of a photoinitiator.

[0208] Advantageously, the irradiation is conducted at a temperature ranging from 0°C to 200°C, in particular from 5 to 150°C, preferably from 10 to 100°C.

[0209] Irradiation is typically conducted at atmospheric pressure. It can be carried out under air or under an inert atmosphere, particularly under N2 scanning.

[0210] Preferably, irradiation is carried out at a wavelength ranging from 250 nm to 500 nm, preferably from 300 to 450 nm, preferably from 350 to 400 nm, and especially 365 nm. A person skilled in the art will be able to adjust the irradiation power according to, in particular, the wavelength and the distance between the wave source and the composition to be irradiated.

[0211] The duration of irradiation typically varies from 0.1 s to 240 minutes, notably from 1 s to 180 minutes.

[0212] Advantageously, the photoinitiator is present at a content less than or equal to 5% by mass, more preferably less than or equal to 1% by mass relative to the total mass of the photocurable composition.

[0213] The photoinitiators are as defined above.

[0214] 3. Uses of the photocurable composition

[0215] The photocurable composition according to the invention is also useful for the preparation of products by 3D printing. Examples of such products include patches for diffusing active ingredients, implants, particles (including micro- and macroparticles), coatings, fibers and threads, etc.

[0216] Indeed, during 3D printing, the photocurable composition undergoes crosslinking. Specifically, 3D printing involves a focused irradiation step in a bath containing the photocurable composition, to form the products layer by layer through photocrosslinking. Alternatively, during 3D printing, the photocurable composition can be crosslinked by thermal crosslinking.

[0217] The invention therefore also relates to the use of the photocurable composition for the preparation of products by 3D printing, preferably by 3D printing with photocuring. Examples of such technologies are stereolithography (SLA), so-called "Digital Light Processing" (DLP) printing processes, "Continuous Liquid Interface Production" (CLIP), "Daylight Polymer Printing" (DPP), or "Film Transfer Imaging" (FTI).

[0218] 4. Photoreticulated composition

[0219] The invention also relates to a crosslinked composition obtained by crosslinking, in particular thermal crosslinking and / or photocrosslinking, of the photocrosslinkable composition according to the invention. According to one embodiment, the crosslinked composition can be obtained by the photocrosslinking process described above.

[0220] According to another variant, the crosslinked composition is likely to be obtained by thermal crosslinking, in particular with thermal initiation optionally in the presence of initiators chosen in particular from producers of radicals by thermal decomposition, such as peroxides, such as cumene hydroperoxide, or azo, such as azobiisobutyronitrile (AIBN), in dispersed or non-dispersed medium.

[0221] The photocrosslinked composition advantageously has a storage modulus G' at 37°C and 10 Hz varying from 0.05 to 10 MPa and preferably from 0.2 to 2 MPa.

[0222] METHODS

[0223] Structural analysis: NMR

[0224] Structural analysis, as well as the determination of the C=C double bond ratio and the proportion of unreacted anhydride or itaconic acid (residuals) present in the polymer, are performed by NMR analysis. Spectra are acquired on a BRUKER Avance III 600 MHz spectrometer equipped with a 5 mm BBFO-zgrad broadband probe. The NMR experiment 1 Quantitative H uses a simple 30° pulse sequence and a 3-second repetition delay between each of the 64 acquisitions. The samples are solubilized in a deuterated solvent, deuterated acetone (acetone d 6 ) unless otherwise indicated. The NMR spectrum 1 H coupled to 2D HSQC / HMBC and NMR experiments 13 C allow the quantification of the microstructure of the different polyesters (see allocation tables).

[0225] Macrostructure analysis: SEC RI

[0226] The SEC (Size Exclusion Chromatography) technique separates macromolecules in solution according to their size using columns filled with a porous gel. Macromolecules are separated according to their hydrodynamic volume, with the largest being eluted first.

[0227] While not an absolute method, SEC allows us to understand the molar mass distribution of a polymer. From commercial standard products, the various number-average (Mn) and weight-average (Mw) molar masses can be determined, and the polydispersity index (D = Mw / Mn), also called "dispersity," can be calculated.

[0228] The macrostructure of the copolyesters was analyzed by size-exclusion chromatography with differential refractometer detection (SEC RI), using low-weight polystyrene (PS) calibration with medium-weight standards. Samples were dissolved at a concentration of approximately 1 g / L in butylated hydroxytoluene (BHT)-free THF, then stirred for two hours before injection. The analysis temperature was 35°C, with a mobile phase flow rate of 1 mL / minute on Agilent 2 Mixed E + 2 Mixed 2 columns. Structural analysis: MIR

[0229] Kinetic monitoring of photocrosslinking was carried out with a mid-infrared (MIR) spectrometer with wavelengths between 4000 and 650 cm⁻¹ 1The Vertex 70 spectrometer (marketed by Bruker) is equipped with a germanium crystal and features an MCT detector. A scan count (Ns) of 32 is used. The spectrometer is equipped with a 9mW / cm² 365nm UV LED lamp. 2 irradiating at a distance of 5 cm from the sample. Crosslinking is monitored by tracking the disappearance of the C=C band of itaconate at 1638 cm⁻¹ 1 depending on the UV irradiation time (peak area measurement of the band at 1638cm' 1 ).

[0230] Measurement of mechanical properties: storage module G'

[0231] Mechanical properties are measured on an Anton Paar MCR302 rheometer, equipped with a 20mm diameter plane-plane geometry. Measurements are performed on a cylindrical sample 2mm thick and 2cm in diameter, obtained by molding in a metal mold followed by curing for 1 hour under a UV LED lamp (365nm LED, 9Mw / cm2) at room temperature.

[0232] This sample is subjected to a frequency sweep from 0.1 to 100 Hz under sinusoidal shear loading at 0.1% strain, at a temperature of 37°C. The resulting stress is measured. The results used are the storage modulus (G') at 37°C and 10 Hz, expressed in megapascals (MPa).

[0233] The moduli G*, G' and G” are calculated according to the equations below:

[0234] (J with

[0235] • o the measured stress and E the deformation imposed on the sample.

[0236] • G', the real part of G*, called the conservation modulus, which characterizes the stiffness of the viscoelastic material. G' characterizes the elastic behavior (the energy conserved and totally released by the material);

[0237] • i, the "imaginary" unit (i 2 = -1);

[0238] • G", the imaginary part of G*, called the loss modulus or dissipation modulus, which characterizes the viscous behavior (the energy dissipated as heat).

[0239] EXAMPLES

[0240] The following examples are given for illustrative purposes only, but should in no way be considered as limiting the present invention. I. Synthesis of photocrosslinkable copolyesters

[0241] Example 1: Synthesis of unfunctionalized glycerol-co-sebacate copolyester, denoted PGS

[0242] In a 500 mL double-jacketed reactor equipped with a distillation column, condenser, and distillate recovery trap, glycerol (1 molar equivalent) and sebacic acid (1 molar equivalent) are added under a nitrogen flow. The reactor is then gradually heated to 130 °C with stirring and nitrogen. Once the temperature reaches 130 °C, the reaction is allowed to proceed for 24 hours under atmospheric pressure and a nitrogen flow. At 130 °C, water is continuously removed. When the conversion exceeds 80%, as measured by the amount of water produced, the reaction is stopped.

[0243] The PGS thus obtained is recovered as a white paste after cooling to room temperature. It has a number molar mass of approximately 1852 g / mol, a mass molar mass Mw of approximately 5067 g / mol, a dispersity of approximately D = 2.7, and a free hydroxyl content of 5 mmol / g.

[0244] Example 2: Synthesis of photocrosslinkable copolyesters according to the invention: itaconate-grafted glycerol-co-sebacetate copolyester

[0245] In the following we will note PGS-IA a copolyester:glycerol-co-sebacate grafted itaconate obtained with itaconic acid as the acrylic monomer.

[0246] In a 500 mL double-jacketed reactor fitted with a distillation column, condenser, and distillate recovery trap, under a nitrogen flow, the PGS of Example 1, the itaconic crosslinking agent (0.4 mol equivalent relative to the 1,3-diacylglyceride motifs of the PGS of Example 1 (major motif)), and 4-methoxyphenol as a stabilizing agent (1.56 wt% relative to the total mass of the mixture including the stabilizing agent) are added. The reactor is then gradually heated to 130 °C under stirring and nitrogen. Once the temperature of 130°C is reached in the medium, the reaction is left under atmospheric pressure and nitrogen flow, at 130°C with water removed continuously during the reaction time indicated in Table 1. A light yellow viscous liquid is obtained, corresponding to PGS-IA, and is then cooled to room temperature.

[0247] The test procedure is carried out without solvents.

[0248] The reaction conditions of the different examples are summarized in Table 1.

[0249] [TABLE 1] The characteristics of PGS-IA obtained in test 1 are shown in tables 2 and 3.

[0250] Table 2: Results of NMR analyses (acetone d 6 ) of the PGS-IA.

[0251] *Takes into account the unsaturations of free and grafted itaconic acid or anhydride

[0252] Table 3: Calculation of the number-average molar masses (Mn) and mass-average molar masses (Mw) and dispersity by SEC analysis (dissolution in THF, poly(styrene) standard) of PGS-IA. [TABLE 3]

[0253] II - Photocurable composition according to the invention

[0254] Example 3: Preparation of a photocurable composition according to the invention

[0255] The polymer in example 2 is mixed with (mass percentages are expressed relative to the total mass of the composition):

[0256] - 0 to 19% of a co-crosslinking agent:

[0257] U DMA, CAS No. = 72869-86-4),

[0258] - 0 to 35% of 2-(diethylamino)ethyl methacrylate as monomer, and

[0259] - optionally 0.5% and 5% by mass, preferably 1% by mass, of a photo-trigger selected from 2,4,6-Trimethylbenzoyldi-Phenylphosphinate (TPO L, TCI, CAS 84434-11-7, 95% by mass), diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO, Sigma Aldrich, CAS 75980-60-8, 97% by mass), or 1-Hydroxycyclohexyl phenyl ketone (HCHPK, Sigma Aldrich, CAS 947-19-3, 99% by mass).

[0260] The compositions obtained are described in Table 4. In these compositions, the PGS-IA is that of Example 2, the photoinitiator used is TPO L, and the compound used is 2-(diethylamino)ethyl methacrylate.

[0261] [TABLE 4]

[0262] Example 4: Photocrosslinking

[0263] The compositions in example 3 are positioned under a UV lamp (LED 365nm, 9 mw / cm2) for an exposure time of 1 to 240 minutes (typically 60 min), at room temperature and atmospheric pressure.

[0264] The progress of crosslinking is defined by mid-infrared monitoring (Ml R, ATR Monoreflection equipped with a germanium crystal) via the disappearance of the C=C band of itaconate at 1638 cm⁻¹ 1as a function of UV irradiation time, by monitoring the evolution of the glass transition temperature, Tg by differential scanning calorimetry (DSC), by the evolution of the complex shear modulus, G* by MCR rheometer. Kinetics

[0265] The kinetics of photocrosslinking are determined by infrared (particularly MIR, Mid-Infrared) monitoring of the disappearance of the C=C band of itaconate (at 1638 cm⁻¹). -1 ) as a function of time. More precisely, a drop of the composition is placed on the germanium crystal (in an ATR Mono-reflection apparatus) and then irradiated under a UV lamp (365 nm, 9 mW / cm²) placed 5 cm from the crystal, and the reaction in the drop on the crystal is monitored. The times indicated (in seconds) in Table 5 correspond to the minimum time required for the complete disappearance of the C=C band of itaconate (at 1638 cm⁻¹). -1 ).

[0266] [TABLE 5]

[0267] It is observed that the reaction kinetics are significantly increased in the presence of a co-crosslinking agent of formula (I).

[0268] The effect is even more significant in the presence of the co-crosslinking agent and a monomer. Conversely, the addition of the monomer alone (i.e., without a co-crosslinking agent) negatively impacts the crosslinking kinetics.

[0269] Storage module

[0270] The storage modulus is also measured on compositions 1 to 4 after photocrosslinking described previously for 60 minutes.

[0271] The results are shown in Table 6. They demonstrate that the value of the storage module is significantly increased with the composition according to the invention.

[0272] [TABLE 6]

Claims

DEMANDS 1. Photocurable composition comprising: - a photocrosslinkable copolyester selected from (i) a copolyester whose constituent units are derived from the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, or (ii) a copolyester whose constituent units are derived from the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being further functionalized with an acrylic monomer, the acrylic monomer being selected from itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, mesaconic anhydride, (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride, Ci-Ce alkyl esters of (meth)acrylic acid, or a mixture thereof; and - a co-crosslinking agent comprising at least two reactive functional groups for crosslinking, in particular for photocrosslinking; the co-crosslinking agent corresponds to one of the following formulas (II) and (III): G-F'-aliphatic chain-F'-E-F'-aliphatic chain-F'-G (II) G-[O-CH2CH2]nOEO-[CH2CH2O] m -G (III) where each G independently represents -C(O)-CR1=CR2R3 with R1 representing H or alkyl in Ci-Ce, the alkyl group in Ci-Ce can be unsubstituted or substituted for example by -O(alkyl in Ci-Ce), -COOH, -COO(alkyl in Ci-Ce), NRnlRn2 OR NRnlRn2Rn3 + X", R2 representing H or alkyl in Ci-Ce, the alkyl in Ci-Ce is advantageously unsubstituted, and R3 representing H, -alkyl in Ci-Ce, -COOH, or -COO(alkyl in Ci-Ce); with Rni, R n 2 and R n 3 independently representing H or alkyl in Ci-Ce, and X' representing a counterion carrying a negative charge such as a halide, a hydrogen sulfate (HSO4') or a bisulfite (HSOs'); the aliphatic chain is a linear or branched, saturated or unsaturated divalent aliphatic chain, advantageously comprising from 2 to 6 carbon atoms; E is a linear or branched, saturated or unsaturated, divalent aliphatic chain, one or more unsaturations of which may be epoxidized, of 1 to 24 carbon atoms, advantageously of 1 to 12 carbon atoms, in which 1 or more, in particular 1 to 4 methylene units (preferably non-adjacent) are optionally replaced by -C(O)-, -0-, -0-0(0)-, -C(0)-0-, -NH-C(O)-, -N(Ci-C6 alkyl)-C(O)-, -C(O)-NH-, -C(O)-N(Ci-C6 alkyl)-, -S-, -S(0)-, -S(0)2-, -NH-, -N(Ci-Ce alkyl)-, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group; said aliphatic chain being optionally substituted, for example, by one or more, preferably 1 to 2, -OH or -O- Ci-Ce alkyl substituents; each F' is identical and is chosen from -O-, -NH-, -NR- a -, -S, -S(0)-, -S(0)2-, R a being any substituent such as an alkyl in Ci-Ce, advantageously F' is -O- ; with n and m independently representing an integer from 1 to 4, or the co-crosslinking agent corresponds to one of the following formulas (IV) and (V): where each G independently represents -C(0)-CR1 =CR2R3 with R1, R2 and 3 being as defined above; each F' is identical and is chosen from -O-, -NH-, -NRa -, -S-, -S(0)-, -S(0)2-, R a being any substituent such as an alkyl in Ci-Ce, advantageously F' is -O-; Ei is any spacer, advantageously a linear or branched tri- or tetra-valent aliphatic chain, saturated or unsaturated, of 1 to 12 carbon atoms, advantageously of 1 to 6 carbon atoms; each E2 is independently any spacer, advantageously a linear or branched, saturated or unsaturated, divalent aliphatic chain, one or more unsaturations which may be epoxidized, of 1 to 30 carbon atoms, wherein one or more, in particular 1 to 4 methylene units, preferably non-adjacent, are optionally replaced by -C(0)-, -O-, -0-0(0)-, -C(0)-0-, -NH-C(O)-, -N(Ci-C6 alkyl)-C(O)-, -C(O)-NH-, -C(O)-N(Ci-C6 alkyl)-, -S-, -S(0)-, -S(0)2-, -NH-, -N(Ci-Ce alkyl)-, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, said aliphatic chain being optionally substituted; I is an integer with a value of 0 or 1; j is an integer with a value of 0 or 1; X, Y and Z each represent, independently of each other, -B or -(E2)kG with B any substitute, k is an integer equal to 0 or 1, E2 any spacer, G independently represents -C(O)-CR1=CR2R3 with R1, R2 and R3 being as defined above; B advantageously represents a linear or branched monovalent aliphatic group, saturated or unsaturated, one or more unsaturations which may be epoxidized, of 1 to 30 carbon atoms, in which 1 or more, in particular 1 to 4 methylene units, preferably non-adjacent, are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, -NH-C(O)-, -N(Ci-C6 alkyl)-C(O)-, -C(O)-NH-, -C(O)-N(Ci-C6 alkyl)-, -S-, -S(O)-, -S(O)2-, -NH-, -N(Ci-Ce alkyl)-, a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group, said aliphatic group being optionally substituted.

2. Composition according to claim 1, characterized in that the photocrosslinkable copolyester has a C=C double bond ratio greater than or equal to 0.004 mmol / g, preferably greater than or equal to 0.04 mmol / g or 0.1 mmol / g, advantageously greater than or equal to 0.5 mmol / g, more preferably greater than or equal to 1 mmol / g.

3. Composition according to claim 1 or 2, characterized in that the acrylic monomer is selected from itaconic acid, itaconic anhydride, (meth)acrylic acid, (meth)acrylic anhydride, or a mixture thereof.

4. Composition according to any one of claims 1 to 3, characterized in that the co-crosslinking agent is selected from the group consisting of the compounds: independently an integer ranging from 1 to 4, 5. Composition according to any one of claims 1 to 4, characterized in that the co-crosslinking agent is present at a content of 5% to 90%, in particular 10% to 80%, preferably 15% to 50%, by mass relative to the total mass of the composition.

6. Composition according to any one of claims 1 to 5, further comprising a photoinitiator, advantageously in a content of 0.05% to 5%, preferably 0.1% to 4%, in particular 0.2% to 3%, by mass relative to the total mass of the composition.

7. A composition according to any one of claims 1 to 6, further comprising a compound M, liquid at room temperature and comprising a radical polymerizable function, this radical polymerizable function advantageously being an acrylic function, typically of formula representing H or a C(O)ORf group, and with Rf representing H, or a C1-C10 alkyl, the C1-C10 alkyl group being unsubstituted or substituted by one or more, preferably one or two, C1-Ce alkoxy, C2-C6 alkenyl, NR group(s) P IR P 2 or NR P IR P 2R P 3 + X', with R P i, R P 2 and R P 3 independently representing H or an alkyl group in Ci-Ce and X' representing a counterion carrying a negative charge such as a halide, a hydrogen sulfate (HSC r) or a bisulfite (HSO ), JV IW the acrylic group being linked to the rest of the molecule by the i bond.

8. Composition according to claim 7, characterized in that compound M is a compound of formula (XI), (XII), (XIII) or (XIV): in which: R represents H or an alkyl group in Ci-Ce, preferably H or a methyl group, Rf and Rf independently represent H, a C1-C10 alkyl group, the alkyl group in C1-C being unsubstituted or substituted by one or more, preferably one or two, alkoxy group(s) in C1-C2, alkenyl in C2-C6, NR n iR n 2 or NR n iR n 2Rn3 + X-, with R ni , Rn2 and Rn3 independently represent H or an alkyl group in Ci-Ce, and X- represents a counterion carrying a negative charge such as a halide, a hydrogen sulfate (HSC r) or a bisulfite (HSCh').

9. Composition according to claim 7 or 8, characterized in that compound M is present at a content ranging from 1% to 90%, in particular from 10% to 80%, preferably from 30% to 70%, by mass relative to the total mass of the composition.

10. Composition according to any one of claims 1 to 9, characterized in that the photocrosslinkable copolyester has at least one of the following characteristics: its number-average molar mass (Mn) measured by size-exclusion chromatography is greater than or equal to 500 g / mol, in particular greater than or equal to 1000 g / mol; its number-average molar mass (Mn) measured by size exclusion chromatography is less than 10,000 g / mol, in particular less than or equal to 3,500 g / mol, preferably less than or equal to 3,000 g / mol; its dispersity D (Mw / Mn) measured by size exclusion chromatography is less than 10, preferably less than or equal to 8, in particular less than or equal to 6.

11. A method for photocrosslinking the photocrosslinkable composition according to any one of claims 1 to 10, comprising a step of UV irradiation of the photocrosslinkable composition.

12. Crosslinked composition obtained by crosslinking the photocrosslinkable composition according to any one of claims 1 to 10.

13. Crosslinked composition according to claim 12, characterized in that it has a storage modulus G' at 37°C and 10 Hz varying from 0.05 to 10 MPa and preferably from 0.2 to 2 MPa.

14. Use of the photocurable composition of any one of claims 1 to 10 for the preparation of products by 3D printing.

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