Additive manufacturing method for producing a silicone elastomer article

Abstract

The invention relates to an additive manufacturing method for producing a silicone elastomer article, the method comprising the following steps: i) providing a photocrosslinkable silicone composition X and an irradiation source, said photocrosslinkable silicone composition X comprising: a) at least one organopolysiloxane A including at least one (meth)acrylate group, and b) at least one radical photoinitiator B as defined in the present invention; ii) selectively irradiating at least a portion of the photocrosslinkable silicone composition X by means of the irradiation source to form a portion of the silicone elastomer article; and iii) repeating step ii) enough times to produce the silicone elastomer article.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: Additive manufacturing method for producing a silicone elastomer article

[0003] Technical field

[0004] The subject of the present invention is an additive manufacturing method for producing an article by 3D printing from a photocrosslinkable composition X comprising at least one organopolysiloxane and at least one type I photoinitiator. In particular, this method makes it possible to produce an article by 3D printing from a photocrosslinkable composition X comprising at least one organopolysiloxane (meth)acrylate and a photoinitiator as defined in the present invention.

[0005] Technological background

[0006] Nowadays, additive manufacturing is experiencing very strong momentum and has phenomenal growth potential due to its emergence and the multiple applications of the articles thus obtained.

[0007] More recently, 3D techniques have been developed with better printing resolution, relatively high printing speed, flexibility in modeling parts while having a low cost during production.

[0008] A key element of the progress made in this technological field has been the development of new photoinitiators or new photoinitiator systems.

[0009] The design of these new photoinitiators allows to reduce the time of additive manufacturing of the part but also allows, through its properties, to work at lower energy and to obtain more complex products.

[0010] In the field of radical polymerization of acrylic silicone compositions, the photoinitiator molecules commonly used are so-called type I photoinitiators. Under irradiation, these molecules split and produce free radicals. These radicals induce the polymerization initiation reaction which results in the hardening of the compositions. Many efforts have been made to ensure that type I photoinitiators have characteristics allowing their use in acrylic silicone formulations to obtain non-stick coatings. For the entire application, the expression "type I photoinitiators" means compounds capable of generating polymerization initiating free radicals under irradiation by intramolecular homolytic fragmentation.

[0011] Type I photoinitiators are commonly used, but they can have disadvantages. In particular, the solubility of these photoinitiators in silicone compositions is not always optimal. In addition, photoinitiators and their degradation products, such as benzaldehyde, pose health risks and can have an unpleasant odor.

[0012] Indeed, commonly used type I photoinitiators such as TPO-L (CAS 84434-11-7) could be banned in the food and health industries in the coming years due to their toxicity.

[0013] Furthermore, TPO-L, in addition to its toxicity to humans, is classified as ecotoxic by the European Chemicals Agency (ECHA).

[0014] In addition to these toxic properties, TPO-L in the presence of at least 10% fillers such as silica or other fillers with hydroxyl groups, sees an exponential increase in its viscosity. This high viscosity makes the execution of the additive manufacturing method complex or even impossible.

[0015] The use of these fillers at high mass percentages makes it possible in particular to obtain silicone articles with improved, diversified mechanical properties and thus to increase tenfold the applications of articles obtained using an additive manufacturing method.

[0016] It is therefore essential to develop type I photoinitiators compatible with such charges.

[0017] It is therefore necessary to develop type I photoinitiators that can overcome these disadvantages.

[0018] In this context, the present invention aims to satisfy at least one of the following objectives.

[0019] One of the essential objectives of the invention is the provision of an additive manufacturing method comprising a silicone composition photocrosslinkable by irradiation with a type I photoinitiator having satisfactory or even improved properties at low content of active species.

[0020] Another essential objective of the invention is the provision of an additive manufacturing method comprising a silicone composition photocrosslinkable by irradiation with a type I photoinitiator having no toxic properties for humans or the environment.

[0021] Another essential objective of the invention is the provision of an additive manufacturing method comprising a silicone composition photocrosslinkable by irradiation with a type I photoinitiator having satisfactory photochemical properties and compatible with a filler content in the composition greater than 20% relative to the total mass of the composition.

[0022] Another essential objective of the invention is the provision of a compound which can be used as a radical photoinitiator in additive manufacturing methods. Another objective of the present invention is that this photocrosslinkable silicone composition comprising a type I photoinitiator can be used to form non-stick coatings.

[0023] Another objective of the present application is to develop a type I photoinitiator suitable for a low or very low energy additive manufacturing method corresponding respectively to the wavelengths 385nm and 405nm.

[0024] Other objectives will appear upon reading the description of the invention which follows.

[0025] Surprisingly, the applicant has developed an additive manufacturing method where the developed type I photoinitiator meets the requirements mentioned above. To do this, the photoinitiators of the present invention are prepared according to a preparation method analogous to those disclosed in patent applications WO2014 / 053455 or WO2018 / 050901.

[0026] Summary of the invention

[0027] Thus, the invention relates to an additive manufacturing method for producing a silicone elastomer article, said method comprising the following steps: i) implementing a photocrosslinkable silicone composition X and an irradiation source, said photocrosslinkable silicone composition X comprising: a) at least one organopolysiloxane A comprising at least one (meth)acrylate group b) at least one radical photoinitiator B represented by the formula (I): Formula (I) in which,

[0028] R represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably a linear or branched C1-C18 group, said alkylene and heteroalkylene groups comprising at least one siloxane function;

[0029] Ri represents a group of formula (II): Formula (II) in which Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0030] -an alkyl group of 1 to 6 carbon atoms, -an alkenyl group of 2 to 4 carbon atoms,

[0031] -a heteroatom O, N or S,

[0032] -a halogen,

[0033] -a SiMe3 group,

[0034] -a hydroxyl group (OH),

[0035] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5;

[0036] R2 represents:

[0037] -a Ri group

[0038] - an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0039] -an alkyl group of 1 to 6 carbon atoms,

[0040] -an alkenyl group of 2 to 4 carbon atoms,

[0041] -a heteroatom O, N or S,

[0042] -a halogen,

[0043] - a SiMes group,

[0044] -a hydroxyl group (OH),

[0045] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2Hs; ii) Selectively irradiating at least a portion of the photocrosslinkable silicone composition X by means of the irradiation source to form a portion of the silicone elastomer article; and iii) Repeating step ii) a sufficient number of times to produce the silicone elastomer article.

[0046] The radical photoinitiator B defined according to the method of the present invention makes it possible to obtain a photocrosslinkable silicone composition X having good properties in terms of conversion and reaction kinetics.

[0047] This radical photoinitiator B has good solubility in silicones. It is therefore possible to use the pure photoinitiator, by diluting it directly in organopolysiloxane A.

[0048] Advantageously, the radical photoinitiator B can be solubilized in the organopolysiloxane A in less than 10 hours, or in less than 5 hours, or in less than 2 hours. For example, this solubility can be determined by adding between 1 and 10 parts by mass of radical photoinitiator B in 100 parts by mass of organopolysiloxane A. In addition, the use of the radical photoinitiator B according to the method of the present invention allows good crosslinking of the photocrosslinkable composition X as well as the transparency of the silicone elastomer article obtained after crosslinking.

[0049] It should be noted that the degradation products of the radical photoinitiator B as defined in this application present satisfactory initial toxicological data.

[0050] In the present application, the term "silicone composition photocrosslinkable by irradiation" means a silicone composition comprising at least one organopolysiloxane capable of curing by electronic or photonic irradiation. Among electronic irradiations, mention may be made of exposures to an electron beam. Among photonic irradiations, mention may be made of exposures to radiation with a wavelength between 200 nm and 450 nm, in particular UV radiation, or exposures to gamma rays.

[0051] By "(meth)acrylate" is meant a methacrylate group or an acrylate group.

[0052] By "alkyl" is meant a straight or branched alkyl group. The alkyl group preferably comprises 1 to 6 carbon atoms.

[0053] By "alkylene" is meant a divalent, linear or branched alkyl group which may have unsaturated bonds. The alkylene group preferably comprises between 1 and 50 carbon atoms, preferably between 1 and 10 carbon atoms and more preferably between 1 and 6 carbon atoms.

[0054] By "heteroalkylene" is meant a divalent, linear or branched heteroalkyl group which may have unsaturated bonds. The heteroalkylene group comprises between 1 and 50 carbon atoms, preferably between 1 and 18 carbon atoms, and between 1 and 6 heteroatoms selected from the group consisting of O, N and S, where N and S may be optionally oxidized. The heteroatoms may be placed at any position in the heteroalkyl group, intersecting the chain or at any position in the chain (internal or at an end of this chain).

[0055] Preferably, the “heteroalkylene” group as defined in the present invention comprises at least one ester function in its carbon chain.

[0056] In the present application, the "shear velocity" or "shear rate" measures the shear applied within the fluid. Thus, viscometers of cone-plane geometry allow, from an angular speed of rotation in a sample (proportional to the shear velocity), to proportionally deduce the viscosity of this sample. Unless otherwise indicated, all the viscosities referred to in the present application correspond to a viscosity quantity measured at 25°C according to the ASTM D4287 standard. In the present application, all percentages are indicated in mass percentages, unless otherwise indicated. Detailed description of the invention

[0057] In general, all additive manufacturing processes have a common starting point, which is a computer data source or a computer program that can describe an object. This computer data source or computer program can be based on a real or virtual object.

[0058] For example, a real object can be scanned using a 3D scanner and the obtained data can be used to generate the computer data source or computer program.

[0059] Alternatively, the computer data source or computer program can be designed from scratch.

[0060] The computer data source or computer program is usually converted into a stereolithography (STL) file, however, other file formats can be used. The file is usually read by 3D printing software, which uses the file and, possibly, user input, to separate the object into hundreds or thousands of "layers."

[0061] Typically, 3D printing software transfers instructions to the machine, for example in the form of G-code, which are read by the 3D printer, which then builds the objects, usually layer by layer.

[0062] Additive manufacturing methods via photopolymerization are a rapidly expanding technology. It is initiated from a photocurable liquid composition, deposited locally on a surface and then crosslinked. Alternatively, the photocurable liquid composition is placed in a vat and then selectively crosslinked.

[0063] Various additive manufacturing method techniques are known to those skilled in the art, such as laser stereolithography (SLA), digital light processing (DLP), continuous liquid interface production (CLIP), ink deposition or extrusion.

[0064] Advantageously, in the context of the present application the additive manufacturing method is an additive manufacturing method by vat photopolymerization, in particular, by laser stereolithography printing (SLA), by digital light processing (DLP), or by continuous liquid interface production (CLIP) or by using a process where the radiation is transmitted through a liquid crystal display (LCD).

[0065] These technologies and the associated equipment are well known to those skilled in the art, who will know how to choose the appropriate technique and the corresponding 3D printer.

[0066] These technologies and equipment are for example described in the following documents: WO2015 / 197495, US5236637, WO2016 / 181149 and WO2014 / 126837. The irradiation source can be any irradiation source which allows photocrosslinking of the photocrosslinkable silicone composition X.

[0067] Advantageously, the irradiation source is a light source, preferably an ultraviolet (UV), visible, or infrared (IR) light source. In general, UV light sources have a wavelength between 200 and 400 nm, visible light sources between 400 and 700 nm, and IR light sources have a wavelength greater than 700 nm, for example between 700 nm and 1 mm, or between 700 and 10,000 nm.

[0068] The light source can be a gas vapor lamp, diodes such as light-emitting diodes, or a laser.

[0069] Preferably, the irradiation source is selected from UV lamps, UV lasers, visible lamps, visible lasers, IR lamps and IR lasers.

[0070] In a particular embodiment of the method, the irradiation source is a block of light emitting diodes (LEDs), preferably a block of light emitting diodes (LEDs) having a wavelength of 355, 365, 385 or 405 nm.

[0071] The power of the irradiation source can be at least 1, 10 or 50 mW / cm 2 It can be between 1 and 1000 mW / cm 2 , preferably between 1 and 500 mW / cm 2 , preferably between 1 and 200 mW / cm 2 , and more preferably between 1 and 50 mW / cm 2 .

[0072] In a particular embodiment, the penetration depth of the irradiation (Dp) is less than 2000 pm for an irradiance of between 1 and 50 mW / cm 2 at 385 or 405nm, preferably the penetration depth is between 100 and 1000 pm, and more preferably between 100 and 500 pm.

[0073] A person skilled in the art will be able to adapt the photoinitiator content, the power of the irradiation source and the duration of irradiation to obtain the desired penetration depth suited to the object.

[0074] In a preferred embodiment, the method does not use a dual cure type composition. In particular, the method does not use a composition that can be crosslinked by polyaddition.

[0075] In one embodiment, the method implements a cleaning step such as a solvent rinse or a post-treatment step such as exposure to an additional radiation source or exposure to heat for a given duration.

[0076] In a particular embodiment, the method does not implement a post-processing step.

[0077] Preferably, the photocurable silicone composition X is implemented in a tank and the silicone elastomer article is produced on a platen, preferably a moving platen. The platen can be any type of platen. Advantageously, the platen is a platform of a 3D printer, such as a moving platform, or a support for one or more layers of the photocurable silicone composition X initially printed with the desired geometry so that they can be detached and crosslinked under irradiation.

[0078] According to a first embodiment of the method, the additive manufacturing method is carried out layer by layer, each layer representing a surface of the photocrosslinkable silicone composition X.

[0079] This first embodiment is particularly suitable for laser stereolithography (SLA) printing and digital light processing (DLP).

[0080] In this first embodiment, the irradiation step ii) may comprise the following sub-steps: a. Depositing a first layer of the photocrosslinkable silicone composition X on a plate b. Selectively irradiating the surface of the photocrosslinkable silicone composition X with an irradiation source to form a crosslinked layer of the silicone elastomer article to be produced; c. Forming an additional layer of photocrosslinkable silicone composition X on the first crosslinked layer produced in step b); and d. Selectively irradiating the additional layer to form an additional crosslinked layer of the silicone elastomer article to be produced.

[0081] The tray on which the layer of photocrosslinkable silicone composition X is deposited during step a) can be any type of tray.

[0082] Preferably, it is a movable tray.

[0083] Advantageously, the tray is a platform of a 3D printer, such as a mobile platform. The support applied to the tray may also comprise the first layer or generally comprise several layers of the photocurable silicone composition X which are selectively deposited and irradiated.

[0084] Preferably, in step d), the additional layer that is formed adheres to the first crosslinked layer of the silicone elastomer article formed in step b).

[0085] Advantageously, the thickness of a layer of photocrosslinkable silicone composition X is between 0.1 and 500 pm, preferably between 5 and 400 pm, preferentially between 10 and 300 pm, and more preferentially between 10 and 100 pm.

[0086] In a particular embodiment, the irradiation time of the layer of photocrosslinkable silicone composition X is at least 0.001 seconds.

[0087] Preferably, the irradiation time is between 0.001 seconds and 10 minutes, preferably between 0.001 seconds and 5 minutes and more preferably between 0.01 seconds and 1 minute.

[0088] These different parameters can be adjusted depending on the desired result. The deposition of a layer of photocurable silicone composition X can be carried out by moving the support, or using a blade, or doctor blade, which deposits a new layer of photocurable silicone composition X.

[0089] Preferably, in the case where the irradiation source is a laser (SLA method for example) the laser traces the surface of the layer of the silicone elastomer article to be produced, in order to have selective irradiation, and in the case where the irradiation source is a block of light-emitting diodes (DLP method for example) it is a single image of the crosslinked layer of the object to be printed which is projected onto the entire surface of the photocrosslinkable composition X.

[0090] Two variants are possible in this first embodiment: additive manufacturing can be carried out by irradiation from above or irradiation from below. These two variants are described in document US5236637.

[0091] In a first variant of this first embodiment, the additive manufacturing is carried out from above: the photocrosslinkable silicone composition X is contained in a tank and the irradiation source is focused on the surface of the photocrosslinkable silicone composition X. The layer which is irradiated is that between the plate and the surface of the photocrosslinkable silicone composition X.

[0092] In this first variant, the deposition of a layer of photocurable silicone composition X is carried out by lowering the plate into the tank by a distance equal to the thickness of a layer. A blade, or doctor blade, can then sweep the surface of the photocurable silicone composition X, which allows it to be flattened.

[0093] In a second variant of this first embodiment, additive manufacturing is from the bottom: the tank comprises a transparent bottom and a non-adhesive surface, and the irradiation source is focused on the transparent bottom of the tank. The layer that is irradiated is therefore the one between the bottom of the tank and the plate.

[0094] In this case, the deposition of a layer of photocurable silicone composition X is carried out by raising the plate to allow the photocurable silicone composition X to be inserted between the bottom of the tank and the plate. The distance between the bottom of the tank and the plate corresponds to the thickness of a layer.

[0095] Advantageously, the additive manufacturing method is a digital light processing (DLP) vat photopolymerization additive manufacturing method, where additive manufacturing is performed from below: the deposition of a layer of photocurable silicone composition X is performed by raising the tray in the vat to allow the photocurable silicone composition X to be inserted between the bottom of the vat and the tray. The distance between the bottom of the vat and the tray corresponds to the thickness of a layer.

[0096] According to a second embodiment, the additive manufacturing method is carried out continuously. This second embodiment is particularly suitable for continuous liquid interface production (CLIP) described in WO2014 / 126837. In this second embodiment, the irradiation step ii) may comprise the following sub-steps, which take place simultaneously: a. Selectively irradiating at least a portion of the photocurable silicone composition X with an irradiation source to form a portion of the silicone elastomer article on the platen; and b. Moving the platen and the portion of the silicone elastomer article formed in step a) away from the irradiation source, along the irradiation axis.

[0097] Advantageously, in step a), the part of the silicone elastomer article is formed on a plate and during step b), it is the plate which is moved simultaneously.

[0098] Preferably, in this second embodiment, the additive manufacturing is carried out by bottom irradiation: the tank comprises a transparent bottom and the irradiation source is focused on the transparent bottom of the tank.

[0099] Thanks to an oxygen-permeable membrane, photopolymerization only takes place at the interface between the photocrosslinkable silicone composition X and the tray; the photocrosslinkable composition X between the bottom of the tank and the interface does not photopolymerize.

[0100] Thus, it is possible to maintain a continuous liquid interface where the silicone elastomer article is formed by irradiating the photocurable composition X and simultaneously moving the portion of the silicone elastomer article formed on the tray outside the tank.

[0101] Once the silicone elastomer article is obtained, it is possible to rinse it in order to remove the non-crosslinked photocrosslinkable silicone composition X.

[0102] Once the silicone elastomer product is obtained, it is also possible to take additional steps to improve the surface quality of the product. The use and application of coatings such as top coats as a final layer can improve the surface quality of the product.

[0103] Spraying or coating the silicone elastomer article with a LSR or RTV silicone composition that can be crosslinked by heating or UV radiation can also be used to achieve a smooth appearance. It is also possible to perform a surface treatment of the resulting article with a laser.

[0104] For medical applications, it is possible to sterilize the resulting silicone elastomer article. Sterilization of the article can be carried out by heating, for example at a temperature above 100°C, either in a dry atmosphere or in an autoclave with steam. Sterilization can also be carried out by gamma rays, with ethylene oxide, or by electron beams.

[0105] The invention also relates to a silicone elastomer article obtained by the method described in the present application. The silicone elastomer article obtained can be any article with a simple or complex geometry. It can for example be silicone molds, masks, pipes, anatomical models (functional or non-functional) such as a heart, a kidney, a prostate, models for surgeons or for teaching, orthoses, prostheses, such as dentures, aligners, mouth guards, or implants of different classes, such as long-term implants, hearing aids, stents, laryngeal implants, etc.

[0106] The resulting silicone elastomer article can also be a cylinder for robotics, a seal, a mechanical part for the automotive or aeronautical industries, a part for electronic devices, a part for encapsulating components, a vibration insulator, an impact insulator or a sound insulator.

[0107] Photocrosslinkable composition

[0108] According to one embodiment, the photocrosslinkable silicone composition X has a dynamic viscosity of between 0.01 and 20 Pa.s at a shear rate of 10s. -1 , preferably between 0.1 and 10 Pa.s, more preferably between 0.1 and 5 Pa.s at a shear rate of 10s -1 .

[0109] In the present application, according to the method of the invention, the photocrosslinkable silicone compositions X comprise at least one organopolysiloxane A.

[0110] Preferably, according to the method of the invention, the photocrosslinkable silicone compositions X comprise at least one organopolysiloxane A comprising at least one (meth)acrylate group, preferably at least 2 (meth)acrylate groups.

[0111] As representatives of (meth)acrylate functions carried by the silicone and particularly suitable for the invention, mention may more particularly be made of acrylate derivatives, methacrylates, (meth)acrylate ethers and (meth)acrylate esters linked to the polysiloxane chain by an Si-C bond.

[0112] According to one embodiment, organopolysiloxane A comprises: a) at least one unit of the following formula (III):

[0113] RaZbSiO(4-ab) / 2 (III) formula in which:

[0114] - the symbols R, identical or different, each represent a linear or branched C 1 to C 8 alkyl group, a C 6 to C 12 aryl or aralkyl group, said alkyl and aryl groups possibly being optionally substituted, preferably by halogen atoms, or a -OR group 5 with R 5 being a hydrogen atom or a hydrocarbon group comprising from 1 to 10 carbon atoms,

[0115] - the symbols Z are monovalent groups of formula -y-(Y')n in which: - y represents a polyvalent C1-C4 alkylene or heteroalkylene group, said alkylene and heteroalkylene groups possibly being linear or branched, and possibly being interspersed with one or more cycloalkylene groups, and possibly being extended by bivalent C1-C4 oxyalkylene or polyoxyalkylene radicals, said alkylene, heteroalkylene, oxyalkylene and polyoxyalkylene groups possibly being substituted with one or more hydroxy groups,

[0116] - Y' represents a monovalent alkenylcarbonyloxy group, and

[0117] - n is equal to 1, 2 or 3, and

[0118] - a is an integer equal to 0, 1 or 2, b is an integer equal to 1 or 2 and the sum a+b= 1, 2 or 3; and b) optionally patterns of the following formula (IV):

[0119] R a SiO(4-a) / 2 (IV) formula in which:

[0120] - the symbols R are as defined above in formula (III), and

[0121] - a is an integer equal to 0, 1, 2 or 3.

[0122] In formulas (III) and (IV) above, the symbols R, which may be identical or different, each represent a linear or branched C 1 -C 12 alkyl group or a C 6 -C 12 aryl or aralkyl group. Preferably, the symbol R represents a monovalent group selected from the group consisting of methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl, and preferably the symbol R represents a methyl.

[0123] Organopolysiloxane A may have a linear, branched, cyclic or network structure. Preferably, organopolysiloxane A has a linear structure. When it comes to linear organopolysiloxanes, these may essentially consist of:

[0124] - siloxyl units “D” chosen from the units of formulas R2SiO2 / 2, RZSiO 2 / 2 and Z2SiO 2 / 2 ;

[0125] - siloxyl units “M” chosen from the units of formulas RsSiOi / 2, R2ZSiOi / 2, RZ2SiOi / 2 and ZsSiOi / 2, and

[0126] - the symbols R and Z are as defined above in formula (III).

[0127] According to one embodiment, in formula (III) above, among the aforementioned Y' alkenylcarbonyloxy groups, mention may be made of acryloxy [CH2=CH-CO-O-] and the methacryloxy group: [CH2=C(CH3)-CO-O-]. Advantageously, the organopolysiloxane A comprises at least 2 Y alkenylcarbonyloxy groups, preferably at least 3 Y' alkenylcarbonyloxy groups.

[0128] As an illustration of the symbol y in the motifs of formula (III), the groups will be mentioned:

[0129] -CH2- ;

[0130] -(CH2)2- ; -(CH2)3- ;

[0131] -CH2-CH(CH3)-CH2- ;

[0132] -(CH2)3-NR'-CH2-CH2- ; with R' being a C1-C6 alkyl group

[0133] -(CH2)3-OCH2- ;

[0134] -(CH2)3-[O-CH2-CH(CH3)-]n-; with n = 1 to 25

[0135] -(CH2)3-O-CH2.CH(OH)(-CH2-) ;

[0136] -(CH2)3-O-CH2-C(CH2-CH3)[-(CH2-)]2;

[0137] -(CH2)3-O-CH2-C[-(CH2)-]3and

[0138] -(CH2)2-C6H9(OH)-.

[0139] Preferably, the organopolysiloxane A corresponds to the following formula (V): formula in which:

[0140] - the R symbols 1 , identical or different, each represent a linear or branched C1-C2 alkyl group, a C6-C12 aryl or aralkyl group, said alkyl and aryl groups possibly being optionally substituted, preferably by halogen atoms, or a -OR group 5 with R 5 being a hydrogen atom or a hydrocarbon group comprising from 1 to 10 carbon atoms,

[0141] - the R symbols 2 and R 3 , identical or different, each represent either a group R 1 is a monovalent group of formula Z = -y-(Y')n in which:

[0142] - y represents a polyvalent C1-C18 alkylene or heteroalkylene group, said alkylene and heteroalkylene groups possibly being linear or branched, and possibly being interspersed with one or more cycloalkylene groups, and possibly being extended by C1 to C4 bivalent oxyalkylene or polyoxyalkylene radicals, said alkylene, heteroalkylene, oxyalkylene and polyoxyalkylene groups possibly being substituted with one or more hydroxy groups,

[0143] - Y' represents a monovalent alkenylcarbonyloxy group,

[0144] - n is equal to 1, 2 or 3, and

[0145] - with a = 0 to 1000, b = 0 to 500, c = 0 to 500, d = 0 to 500 and a+b+c+d= 0 to 2500, preferably a = 0 to 500 and a+b+c+d= 0 to 500,

[0146] - provided that at least one R symbol 2 or R 3 represents the monovalent group of formula Z, preferably at least two R symbols 2 or R 3 represent a monovalent group of formula Z.

[0147] According to a preferred embodiment, in formula (V) above:

[0148] - c=0, d=0, a= 1 to 1000, b= 1 to 250, the symbol R 2 represents the monovalent group of formula Z and the symbols R 1 and R 3 have the same meaning as above.

[0149] Even more preferably, in formula (V) above:

[0150] - c=0, d=0, a= 1 to 500, b= 2 to 100, the symbol R 2 represents the monovalent group of formula Z and the symbols R 1 and R 3have the same meaning as above.

[0151] According to one embodiment, the organopolysiloxane A according to the invention corresponds to one of the following formulas (Via), (Vlb), (Vie) or (Vld): in which:

[0152] R, identical or different, represents a hydrogen atom or a hydroxyl group;

[0153] -xi is an integer between 1 and 1000; preferably xi is between 1 and 500;

[0154] -ni is an integer between 1 and 100, preferably ni is between 2 and 50;

[0155] -X2 is an integer between 1 and 1000, preferably x2 is between 1 and 500;

[0156] -n2 is an integer between 0 and 100, preferably n2 is between 0 and 50;

[0157] - s is an integer between 1 and 1000, preferably x3 is between 1 and 500;

[0158] -n3 is an integer between 0 and 100, preferably n3 is between 0 and 50;

[0159] -X4 is an integer between 1 and 1000, preferably x4 is between 1 and 500;

[0160] -n4 is an integer between 0 and 100, preferably n4 is between 0 and 50;

[0161] -mi, m2, m3 and m4 are integers between 1 and 8.

[0162] According to one embodiment, the organopolysiloxane A according to the invention corresponds to one of the following formulas (Vila), (Vllb), (Vile) or (Vlld): in which:

[0163] - xi is an integer between 1 and 1000; preferably xi is between 1 and 500,

[0164] - ni is an integer between 0 and 100, preferably between 0 and 50,

[0165] - x2 is an integer between 1 and 1000, preferably x2 is between 1 and 500

[0166] - n2 is an integer between 0 and 100, preferably n2 is between 0 and 50,

[0167] - x3 is an integer between 1 and 1000, preferably x3 is between 1 and 500,

[0168] - n3 is an integer between 1 and 100, preferably n3 is between 1 and 50,

[0169] - X4 is an integer between 1 and 500, preferably X4 is between 1 and 200,

[0170] - n4 is an integer between 0 and 100, preferably n4 is between 0 and 50.

[0171] According to the method of the invention, the photocrosslinkable silicone composition X may comprise between 10 and 99.9% by mass of organopolysiloxane A, relative to the total mass of the photocrosslinkable silicone composition X.

[0172] Preferably, the photocrosslinkable silicone composition X may comprise between 10 and 99.5% by mass of organopolysiloxane A, relative to the total mass of the photocrosslinkable silicone composition X.

[0173] Of course, depending on the variants, organopolysiloxane A may be a mixture of compounds meeting the definition of organopolysiloxane A.

[0174] For the purposes of the present invention, the radical photoinitiator B is represented by the formula (I): Formula (I) in which,

[0175] R represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C, said alkylene and heteroalkylene groups comprising at least one siloxane function;

[0176] Ri represents a group of formula (II):

[0177] Formula (II) in which Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0178] -an alkyl group of 1 to 6 carbon atoms,

[0179] -an alkenyl group of 2 to 4 carbon atoms,

[0180] -a heteroatom O, N or S,

[0181] -a halogen,

[0182] -a SiMe3 group,

[0183] -a hydroxyl group (OH),

[0184] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5;

[0185] R2 represents:

[0186] -a Ri group

[0187] - an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0188] -an alkyl group of 1 to 6 carbon atoms,

[0189] -an alkenyl group of 2 to 4 carbon atoms,

[0190] -a heteroatom O, N or S,

[0191] -a halogen,

[0192] -a SiMe group 3]

[0193] -a hydroxyl group (OH),

[0194] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5.

[0195] According to one embodiment of the method of the present invention, the radical photoinitiator B is a compound of formula (VIII): Formula (VIII) in which,

[0196] Ri and R2 represent the groupings as defined previously;

[0197] R3 represents a linear or branched C1-C6 alkylene or heteroalkylene group;

[0198] R4 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably a linear or branched C1-C group, said R4 comprising at least one siloxane function. Preferably, the radical photoinitiator B is a compound of formula (Villa): Formula (Villa) in which, R3 and R4 represent groups as defined previously. Alternatively, the radical photoinitiator B is a compound of formula (VII Ib): Formula (Vlllb) in which R3 and R4 represent groups as defined previously.

[0199] According to one embodiment of the invention, the radical photoinitiator B is an organopolysiloxane comprising: a) at least one RcZdSiO( 4.c -d) / 2 (IX) formula (IX) in which:

[0200] - the symbols R, identical or different, each represent a linear or branched C 1 to C 8 alkyl group, a C 6 to C 12 aryl or aralkyl group, said alkyl and aryl groups possibly being optionally substituted, preferably by halogen atoms, or a -OR group 5 with R 5 being a hydrogen atom or a hydrocarbon group comprising from 1 to 10 carbon atoms,

[0201] - the Z symbols are monovalent groups of formula -y-(Y')n in which:

[0202] - y represents a polyvalent C1-C50 alkylene or heteroalkylene group, preferably C1-C18, said alkylene and heteroalkylene groups being able to be linear or branched, and being able to be optionally interspersed by one or more heteroatoms selected from the group consisting of O, N and S, where N and S can be optionally oxidized; these alkylene or heteroalkylene groups being able to be optionally substituted by one or more hydroxyl groups,

[0203] - Y' represents a group of Formula (X): Formula (X) in which,

[0204] Ri represents a group of formula (XI): Formula (XI) in which Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0205] -an alkyl group of 1 to 6 carbon atoms,

[0206] -an alkenyl group of 2 to 4 carbon atoms,

[0207] -a heteroatom O, N or S,

[0208] -a halogen,

[0209] -a SiMe3 group,

[0210] -a hydroxyl group (OH),

[0211] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5;

[0212] R2 represents:

[0213] -a Ri group

[0214] - an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0215] -an alkyl group of 1 to 6 carbon atoms,

[0216] -an alkenyl group of 2 to 4 carbon atoms,

[0217] -a heteroatom O, N or S,

[0218] -a halogen,

[0219] - a SiMes group,

[0220] -a hydroxyl group (OH),

[0221] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5. -n is equal to 1 or 2;

[0222] -c is an integer equal to 0, 1 or 2, d is an integer equal to 1 or 2 and the sum c+d= 1, 2 or 3; and b) MDT patterns, of formula (XII) as follows:

[0223] RcSiO(4-c) / 2 (XII) formula in which:

[0224] - the symbols R are as defined above in formula (IX), and

[0225] - it is an integer equal to 0, 1, 2 or 3.

[0226] In formulas (IX) and (XII) above, the symbols R, which may be identical or different, each represent a linear or branched C1-C2 alkyl group or a C6-C12 aryl or aralkyl group. Preferably, the symbol R represents a monovalent group selected from the group consisting of methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl, and preferably the symbol R represents a methyl.

[0227] The radical photoinitiator of the present invention B may have a linear, branched, cyclic or network structure. Preferably, the radical photoinitiator B has a linear structure. When linear organopolysiloxanes are involved, these may essentially consist of:

[0228] - siloxyl units “D” chosen from the units of formulas R2SiO2 / 2, RZSiO 2 / 2 and Z2SiO 2 / 2 ;

[0229] - siloxyl units “M” chosen from the units of formulas RsSiOi / 2, R2ZSiOi / 2, RZ2SiOi / 2 and ZsSiOi / 2, and

[0230] - the symbols R and Z are as defined above in formula (IX).

[0231] In the present invention:

[0232] - a siloxyl unit “M” represents a siloxyl unit of formula YsSiOi / 2,

[0233] - a siloxyl unit “D” represents a siloxyl unit of formula Y2SiO2 / 2,

[0234] - a siloxyl unit “T” represents a siloxyl unit of formula YSiO3 / 2,

[0235] - a siloxyl unit “Q” represents a siloxyl unit of formula SiO4 / 2, the symbols Y being an identical or different R group.

[0236] The radical photoinitiator B as defined in formulas (IX) and (XII) may optionally comprise T and Q units.

[0237] According to one embodiment of the method of the present invention, the radical photoinitiator B is a compound of formula (XIII): Formula (XIII) in which,

[0238] Rs identical or different represents:

[0239] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0240] -an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl, -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, -an acrylate or meth(acrylate) group, -a hydroxyl (OH) group,

[0241] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 OR C2H5,

[0242] -a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,

[0243] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched, -a hydrogen,

[0244] -a grouping of formula (XIV): Formula (XIV) in which Ri and R2 represent groups as defined previously Re represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C18; a represents an integer between 0 and 100; said method being characterized in that at least one group Rs is represented by the group of formula (XIV).

[0245] Preferably, the radical photoinitiator B is characterized in that the group of formula (XIV) is represented by the compound of formula (XII la): Formula (Xlla) in which, R6 is as defined previously.

[0246] Alternatively, the radical photoinitiator B is characterized in that the group of formula (XIV) is represented by the compound of formula (XII Ib): Formula (Xlllb) in which, R6 is as defined previously.

[0247] According to one embodiment of the method of the present invention, the radical photoinitiator B is a compound of formula (XV): Formula (XV) in which,

[0248] R7 identical or different represents:

[0249] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0250] - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl;

[0251] - an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl;

[0252] -a hydroxyl group (OH),

[0253] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, -a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200, -an acrylate or meth (acrylate) group,

[0254] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0255] -a hydrogen;

[0256] R8 represents a group as defined for R7 or a group of formula (XVI):

[0257] Formula (XVI) in which R1 and R2 represent groups as defined above; R6 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C; a represents an integer between 0 and 10; b represents an integer between 1 and 100; said method being characterized in that at least one group R8 is represented by the group of formula (XVI).

[0258] Preferably, the group of formula (XVI), as defined above, has the formula: Formula (XVa) in which R6 is as defined above. Alternatively, the group of formula (XVI), as defined above, has the formula: Formula (XVb) in which Re is as defined previously.

[0259] In a particular embodiment of the invention, the radical photoinitiator B is a compound of formula (XV) as defined above where two consecutive siloxane units can be intersected by an O-Si(CH3)2-CH2-CH2-Si(CHs)2 unit.

[0260] In one embodiment, the method of the invention is characterized in that the radical photoinitiator B is a compound of formula (XVII): Formula (XVII) in which,

[0261] R9same or different represents:

[0262] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0263] - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl;

[0264] - an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl;

[0265] -a hydroxyl group (OH),

[0266] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5,

[0267] -a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200, -an acrylate or meth (acrylate) group,

[0268] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0269] -an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms,

[0270] - a carbonyl or carboxyl group,

[0271] -a hydrogen,

[0272] - a grouping of formula (XVIII): Formula (XVIII) in which R1 and R2 represent groups as defined previously R6 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C;

[0273] Rw identical or different represents:

[0274] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0275] -an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl,

[0276] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0277] -a hydroxyl group (OH),

[0278] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2Hs,

[0279] -a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,

[0280] -an acrylate or meth (acrylate) group,

[0281] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0282] -an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms,

[0283] - a carbonyl or carboxyl group,

[0284] -a hydrogen,

[0285] Ru represents a -CH3 group or an oxygen atom;

[0286] Z represents a -CH2- group or an oxygen atom;

[0287] Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0288] -an alkyl group of 1 to 6 carbon atoms,

[0289] -an alkenyl group of 2 to 4 carbon atoms,

[0290] -a heteroatom O, N or S,

[0291] -a halogen,

[0292] -a SiMe3 group,

[0293] -a hydroxyl group (OH),

[0294] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5; m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 100; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 100.

[0295] According to one embodiment, the method of the invention is characterized in that the radical photoinitiator B is a compound of formula (XVII) indicated above: in which, R9 and R™, identical or different, represent:

[0296] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0297] - a hydroxyl group (OH),

[0298] - a hydrogen atom

[0299] Ru represents a -CH3 group or an oxygen atom;

[0300] Z represents a -CH2- group or an oxygen atom;

[0301] Ar represents an aryl group of 6 carbon atoms substituted or not by at least one of the following groups:

[0302] -an alkyl group of 1 to 6 carbon atoms,

[0303] -an alkenyl group of 2 to 4 carbon atoms, -a heteroatom O, N or S,

[0304] -a halogen,

[0305] -a SiMe3 group,

[0306] -a hydroxyl group (OH), m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 10; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 20.

[0307] In one embodiment, the method of the invention is characterized in that the radical photoinitiator B is a compound of formula (XIX): Formula (XIX) in which, R9 and Rw, identical or different, represent:

[0308] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0309] -an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl,

[0310] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0311] -a hydroxyl group (OH),

[0312] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5,

[0313] -a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,

[0314] -an acrylate or meth (acrylate) group,

[0315] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0316] -an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms,

[0317] -a carbonyl or carboxyl group,

[0318] -a hydrogen;

[0319] Ru represents a -CH3 group or an oxygen atom;

[0320] Z represents a -CH2- group or an oxygen atom;

[0321] Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0322] -an alkyl group of 1 to 6 carbon atoms,

[0323] -an alkenyl group of 2 to 4 carbon atoms,

[0324] -a heteroatom O, N or S,

[0325] -a halogen,

[0326] -a SiMe3 group,

[0327] -a hydroxyl group (OH),

[0328] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 100; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 100; said method is characterized in that when a = 1: q> 0 or at least one Rg group is a hydroxyl group.

[0329] According to one embodiment, the method of the invention is characterized in that the radical photoinitiator B is a compound of formula (XIX) indicated above: in which, Rg and Rw, identical or different, represent:

[0330] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0331] - a hydroxyl group (OH),

[0332] - a hydrogen atom

[0333] Ru represents a -CH3 group or an oxygen atom;

[0334] Z represents a -CH2- group or an oxygen atom;

[0335] Ar represents an aryl group of 6 carbon atoms substituted or not by at least one of the following groups: - an alkyl group of 1 to 6 carbon atoms,

[0336] -an alkenyl group of 2 to 4 carbon atoms,

[0337] -a heteroatom O, N or S,

[0338] -a halogen,

[0339] -a SiMe3 group,

[0340] - a hydroxyl group (OH), m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 10; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 20; said method is characterized in that when a = 1: q > 0 or at least one group R9 is a hydroxyl group;

[0341] In one embodiment, the method of the invention is characterized in that the photocrosslinkable composition X further comprises a photoinitiator chosen from the group consisting of type I radical photoinitiators or type II radical photoinitiators.

[0342] Thus, the photocrosslinkable composition X may further comprise a photoinitiator chosen from the group of type I radical photoinitiators such as:

[0343] Acyl phosphine oxides, bis-acyl phosphine oxides and their derivatives such as diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate (TPO-L), phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), benzoin ether, benzoyl oxime, acetophenone & hydroxyacetophenone (HAP), phenylglyoxal, alpha-hydroxyketones, alpha-aminoketones and CPO-1 & CPO-2:

[0344] Examples of commercial products of such photoinitiators include: bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide marketed under the name OMNIRAD™ 819 by IGM Resin BV; liquid mixtures of acylphosphine oxides with at least one other photoinitiator marketed by IGM Resin BV under the name OMNIRAD™ 1000, OMNIRAD™ 2022, OMNIRAD™ 2100 or OMNIRAD™ 4265; 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl), 2-hydroxy-2-methylpropiophenone marketed by IGM Resin BV under the name “OMNIRAD™ 1173”; 2-benzyl-2-(N,N-dimethylamino)-1-(4-morpholinophenyl)-1-butanone marketed by IGM Resin BV under the name OMNIRAD™ 369 or as Irgacure® 369 by Ciba®); 2,2-dimethoxy-1,2-diphenylethan-1-one marketed by Ciba® under the name Irgacure® 651; 2-Methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one marketed by IGM Resin BVunder the name OMNIRAD™ 907 or as Irgacure® 907 by Ciba®); 2-Hydroxy-2-methyl-1-phenyl-1 -propanone marketed by Ciba® under the name Darocure® 1173; 1 -hydroxycyclohexyl phenyl ketone type I (Irgacure 184).

[0345] Thus, the photocrosslinkable composition X may further comprise a photoinitiator chosen from the group of type II radical photoinitiators such as:

[0346] Benzophenones such as 1-hydroxycyclohexyl benzophenone marketed by IGM Resin BV under the name “OMNIRAD™ 184”; thioxanthones such as isopropylthioxanthone, thioxanthone neodecanoate or substituted thioxanthones as disclosed in patent application WO2018 / 234643; xanthenes such as 9-xanthenone; anthraquinones and hydroxyanthraquinones such as 4-dihydroxyanthraquinone, - 2-methylanthraquinone, 2,2'-bis(3-hydroxy-1,4-naphthoquinone), 2,6-dihydroxyanthraquinone, 1,5-dihydroxyanthraquinone, 2-ethylanthraquinone, 2-methylanthraquinone, 1 ,8-dihydroxyanthraquinone, 1,3-diphenyl-1,3-propanedione, 5,7-dihydroxyflavone.

[0347] In one embodiment, the method of the invention is characterized in that the molecular mass by weight of the radical photoinitiator B is between 400 and 10,000 g / mol, preferably between 400 and 5,000, preferentially between 400 and 3,000, even more preferentially between 400 and 2,600 g / mol.

[0348] In one embodiment, the method of the invention is characterized in that the mass percentage of radical photoinitiator B is between 0.1 and 20% relative to the total mass of the photocrosslinkable composition X, preferably between 0.1 and 5%, preferentially between 0.2 and 2%, more preferentially between 0.4 and 1.5% relative to the total mass of the photocrosslinkable composition X.

[0349] In one embodiment, the method of the invention is characterized in that the radical photoinitiator B and the organopolysiloxane A are a single molecule denoted AB. The system is then called an “intramolecular system”.

[0350] In one embodiment the method of the invention is characterized in that compound AB is a compound of formula (XXa), (XXb), (XXc) or (XXd):

[0351] in which,

[0352] R12, identical or different, represents a hydrogen atom or a hydroxyl group;

[0353] R13 identical or different represents:

[0354] -an alkenyl function of 2 to 4 carbon atoms,

[0355] -at least one group of formula (XXI): Formula (XXI)

[0356] Ri and R2 represent the groups as defined previously;

[0357] R14 represents; an alkyl group of 1 to 5 carbon atoms or alkenyl group of 2 to 5 carbon atoms:

[0358] -substituted or not by at least one heteroatom O, N or S,

[0359] -substituted or not by at least one alkyl group of 1 to 5 carbon atoms,

[0360] -substituted or not by at least one aryl group of 6 to 18 carbon atoms, - xi is an integer between 1 and 1,000; preferably xi is between 1 and 500;

[0361] - ni is an integer between 1 and 100, preferably between 2 and 50;

[0362] - x2 is an integer between 1 and 1000, preferably x2 is between 1 and 500;

[0363] - n2 is an integer between 0 and 100, preferably n2 is between 0 and 50;

[0364] - x3 is an integer between 1 and 1000, preferably x3 is between 1 and 500; and

[0365] - n3 is an integer between 0 and 100, preferably n3 is between 0 and 50

[0366] - x4 is an integer between 1 and 1000, preferably x3 is between 1 and 500; and

[0367] - n4 is an integer between 0 and 100, preferably n3 is between 0 and 50;

[0368] -mi, m2, m3 and m4 are integers between 1 and 8.

[0369] In one embodiment the method of the invention is characterized in that compound AB is a compound of formula (XXIIa), (XXIIb), (XXIIc), or (XXIId): in which:

[0370] RI4same or different represents:

[0371] - an alkenyl function of 2 to 4 carbon atoms, - at least one group of formula (XXIII):

[0372] Formula (XXIII)

[0373] Ri and R2 represent the groupings as defined previously;

[0374] R15 represents: an alkyl group of 1 to 5 carbon atoms or alkenyl group of 2 to 5 carbon atoms:

[0375] -substituted or not by at least one heteroatom O, N or S,

[0376] -substituted or not by at least one alkyl group of 1 to 5 carbon atoms, -substituted or not by at least one aryl group of 6 to 18 carbon atoms,

[0377] - xi is between 1 and 1000; preferably xi is between 1 and 500;

[0378] - ni is between 0 and 100, preferably is between 0 and 50;

[0379] - x2 is between 1 and 1000, preferably x2 is between 1 and 500;

[0380] - n2 is between 1 and 100, preferably n2 is between 2 and 50;

[0381] - x3 is between 1 and 1000, preferably x3 is between 1 and 500;

[0382] - n3 is between 1 and 100, preferably n3 is between 0 and 50;

[0383] -X4 is between 1 and 1000, preferably x4 is between 1 and 500.

[0384] -n4 is an integer between 0 and 100, preferably n4 is between 0 and 50.

[0385] Other additives:

[0386] In one embodiment, the method of the invention is characterized in that the photocrosslinkable silicone composition X comprises:

[0387] -from 10 to 99.9% of at least one organopolysiloxane A comprising at least one (meth)acrylate group as defined above

[0388] - from 0.1 to 20% of at least one radical photoinitiator B as defined previously.

[0389] The photocrosslinkable silicone composition X may also comprise other additives such as polymerization inhibitors, fillers, virucides, bactericides, anti-abrasion additives, and pigments (organic or mineral). Among the polymerization inhibitors, mention may be made of phenols, hydroquinone, 4-OMe-phenol, 2,4,6-tritertiary-butyl phenol (BHT), phenothiazine, and nitroxyl radicals such as (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO). The photocrosslinkable silicone composition X may also comprise an organic compound O comprising at least one (meth)acrylate function.

[0390] By organic compound O comprising at least one (meth)acrylate function, we mean any compound comprising one or more (meth)acrylate functions.

[0391] According to one embodiment, the organic compound O comprising at least one (meth)acrylate function does not comprise a siloxane structure.

[0392] Suitable organic compounds O comprising a (meth)acrylate function are, in particular, epoxidized (meth)acrylate compounds, (meth)acryloglyceropolyesters, (meth)acrylouretanes, (meth)acrylopolyethers, (meth)acrylopolyesters, and (meth)acryloacrylics. More particularly preferred are trimethylolpropane triacrylate, tripropylene glycol diacrylate, hexanediol diacrylate, and pentaerythritol tetraacrylate.

[0393] A titre d’exemple de composé organique O comprenant une fonction (méth) acrylate, on peut citer (noms chimiques en anglais): ethylhexyl acrylate, stearyl acrylate, tetra hydrofurfuryl acrylate, lauryl acrylate, isodecyl acrylate, 2(2-ethoxyethoxy)ethyl acrylate, cyclohexyl acrylate, isooctyl acrylate, tridecyl acrylate, isobornyl acrylate, caprolactone acrylate, alkoxylated phenol acrylates, 1 ,3-butylene glycol diacrylate, 1 ,4-butanediol diacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, alkoxylated hexanediol diacrylates, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, pentarythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, et di-pentaerythritol pentaacrylate.

[0394] The photocrosslinkable silicone composition X may comprise from 0 to 50% of organic compound O relative to the total mass of the photocrosslinkable silicone composition X.

[0395] According to one embodiment, the photocrosslinkable silicone composition X further comprises a filler D.

[0396] The photocrosslinkable silicone composition X may comprise from 0 to 50% by mass of filler D, preferably from 10 to 50% of filler D, preferentially from 10 to 40% of filler D, even more preferentially from 20 to 35% of filler D relative to the total mass of the photocrosslinkable silicone composition X.

[0397] According to one embodiment, the photocrosslinkable silicone composition X comprises between 20 and 30% by mass of filler D relative to the total mass of the photocrosslinkable silicone composition X.

[0398] This filler is preferably mineral. Filler D may be a very finely divided product with an average particle diameter of less than 0.1 pm.

[0399] Filler D may be siliceous in particular. Siliceous materials may act as reinforcing or semi-reinforcing fillers. Reinforcing siliceous fillers are chosen from colloidal silicas, combustion and precipitation silica powders, or mixtures thereof.

[0400] These powders have an average particle size generally less than 0.1 pm (micrometers) and a BET specific surface area greater than 30 m 2 / g, preferably between 30 and 350 m 2 / g.

[0401] Semi-reinforcing siliceous fillers such as diatomaceous earth or ground quartz can also be used.

[0402] These silicas can be incorporated as such or after being treated with organosilicon compounds usually used for this purpose. These compounds include methylpolysiloxanes such as hexamethyldisiloxane, octamethylcyclotetrasiloxane, methylpolysilazanes such as hexamethyldisilazane, hexamethylcyclotrisilazane, tetramethyldivinyldisilazane, chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane, dimethylvinylchlorosilane, alkoxysilanes such as dimethyldimethoxysilane, dimethylvinylethoxysilane, trimethylmethoxysilane, and mixtures thereof. As regards non-siliceous mineral materials, they can be used as semi-reinforcing or bulking mineral fillers.

[0403] Examples of these non-siliceous fillers that can be used alone or in a mixture are calcium carbonate, possibly surface-treated with an organic acid or an ester of an organic acid, calcined clay, rutile-type titanium oxide, iron, zinc, chromium, zirconium and magnesium oxides, the different forms of alumina (hydrated or not), boron nitride, lithopone, barium metaborate, barium sulfate and glass microbeads.

[0404] These fillers are coarser with generally an average particle diameter greater than 0.1 pm and a specific surface area generally less than 30 m 2 / g.

[0405] These charges may have been surface modified by treatment with the various organosilicon compounds usually used for this purpose.

[0406] Thus, according to one embodiment, the method of the invention is characterized in that the photocrosslinkable silicone composition X comprises:

[0407] - from 10 to 89.9% of at least one organopolysiloxane A comprising at least one (meth)acrylate group as defined previously;

[0408] - from 0.1 to 20% of at least one radical photoinitiator B as defined previously;

[0409] - from 10 to 50% load D.

[0410] The photocurable silicone composition X may also include a photoabsorber E. The photoabsorber E makes it possible to reduce the penetration of irradiation into the layer of photocurable silicone composition X and thus to improve the resolution of the resulting silicone elastomer article. It makes it possible to control the penetration depth of irradiation (Dp) into the layer of silicone elastomer.

[0411] The photocrosslinkable silicone composition X comprises from 0.01 to 5% by mass of photoabsorber E relative to the total mass of the photocrosslinkable silicone composition X, and preferably the photoabsorber E is chosen from the group consisting of TiO2, ZnO, hydroxylphenyl-s-triazines, hydroxylphenyl-benzotriazoles such as Tinuvin® 384-2, cyanoacrylates, and mixtures thereof. According to one embodiment of the invention, the photocrosslinkable silicone composition X comprises from 0.01 to 1.5% by mass of photoabsorber E relative to the total mass of the photocrosslinkable silicone composition X, preferably from 0.01 to 0.5%, preferentially from 0.01 to 0.2% relative to the total mass of the photocrosslinkable silicone composition X.

[0412] The photocrosslinkable silicone composition X may also include a photostabilizer F.

[0413] Photostabilizer F makes it possible to reduce or even stop the activity of photoinitiators, by trapping the radicals still active after implementing the method of the present invention. This thus makes it possible to increase the transparency properties of the silicone elastomer article obtained according to the method of the invention.

[0414] The photocrosslinkable silicone composition X further comprises from 0 to 2% by mass of photostabilizer F relative to the total mass of the photocrosslinkable silicone composition X, and preferably from 0 to 0.5% by mass of photostabilizer F relative to the total mass of the photocrosslinkable silicone composition X.

[0415] Said photostabilizer F is chosen from the group consisting of hindered amines, cyclic amines of 4 to 6 carbon atoms such as the commercial compounds Tinuvin® 249, Tinuvin®292, Tinuvin®123 and their mixtures.

[0416] Photocrosslinkable composition X2:

[0417] The invention also relates to the photocrosslinkable silicone composition X2 comprising:

[0418] - from 10 to 99.9% by mass of at least one organopolysiloxane A comprising at least one (meth)acrylate group;

[0419] - from 0.1 to 20% by mass of at least one radical photoinitiator B which is a compound of formula (I): Formula (I) in which,

[0420] R represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably a linear or branched C1-C18 group, said alkylene and heteroalkylene groups comprising at least one siloxane function;

[0421] Ri represents a group of formula (II): Formula (II) in which Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0422] -an alkyl group of 1 to 6 carbon atoms,

[0423] -an alkenyl group of 2 to 4 carbon atoms,

[0424] -a heteroatom O, N or S,

[0425] -a halogen,

[0426] -a SiMe3 group,

[0427] -a hydroxyl group (OH),

[0428] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5;

[0429] R2 represents:

[0430] -a Ri group,

[0431] - an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0432] -an alkyl group of 1 to 6 carbon atoms,

[0433] -an alkenyl group of 2 to 4 carbon atoms,

[0434] -a heteroatom O, N or S,

[0435] -a halogen,

[0436] -a SiMe group 3]

[0437] -a hydroxyl group (OH),

[0438] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5.

[0439] Advantageously, the photoinitiator B of the photocrosslinkable composition X2 is a compound chosen from the compounds of formula: (VIII), (XIII), (XVII), (XXa), (XXb), (XXc), (XXd) and / or their mixtures.

[0440] Preferably, the photoinitiator B of the photocrosslinkable composition X2 is a compound chosen from the compounds of formula: (VIII), (XIII), (XVII), (XXa) and / or their mixtures.

[0441] Thus, according to one embodiment, the photocrosslinkable silicone composition X2 comprises:

[0442] - from 10 to 99.9% by mass of at least one organopolysiloxane A comprising at least one (meth)acrylate group;

[0443] - from 0.1 to 20% by mass of at least one photoinitiator B which is a compound of formula (XXIV): Formula (XXIV) in which, R9 identical or different represents:

[0444] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0445] - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl;

[0446] - an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl;

[0447] -a hydroxyl group (OH),

[0448] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5,

[0449] -a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200, -an acrylate or meth (acrylate) group,

[0450] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0451] -an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms,

[0452] - a carbonyl or carboxyl group,

[0453] -a hydrogen,

[0454] - a grouping of formula (XXV): Formula (XXV) in which R1 and R2 represent groups as defined previously R6 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C, Rw, identical or different, represents:

[0455] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0456] -an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl,

[0457] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0458] -a hydroxyl group (OH),

[0459] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2Hs,

[0460] -a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,

[0461] -an acrylate or meth (acrylate) group,

[0462] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0463] -an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms,

[0464] - a carbonyl or carboxyl group,

[0465] -a hydrogen;

[0466] Ru represents a -CH3 group or an oxygen atom,

[0467] Z represents a -CH2- group or an oxygen atom,

[0468] Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0469] -an alkyl group of 1 to 6 carbon atoms,

[0470] -an alkenyl group of 2 to 4 carbon atoms,

[0471] -a heteroatom O, N or S,

[0472] -a halogen,

[0473] -a SiMe3 group,

[0474] -a hydroxyl group (OH),

[0475] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H 5 ; m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 100; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 100.

[0476] According to one embodiment, the photocrosslinkable silicone composition X2 is characterized in that the radical photoinitiator B is a compound of formula (XIX) indicated above: in which, R9 and R™, identical or different, represent:

[0477] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0478] - a hydroxyl group (OH),

[0479] - a hydrogen atom

[0480] Ru represents a -CH3 group or an oxygen atom;

[0481] Z represents a -CH2- group or an oxygen atom;

[0482] Ar represents an aryl group of 6 carbon atoms substituted or not by at least one of the following groups:

[0483] -an alkyl group of 1 to 6 carbon atoms, -an alkenyl group of 2 to 4 carbon atoms,

[0484] -a heteroatom O, N or S,

[0485] -a halogen,

[0486] -a SiMe3 group,

[0487] - a hydroxyl group (OH), m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 10; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 20;

[0488] In a preferred embodiment, the photocrosslinkable silicone composition X2 comprises:

[0489] - from 25 to 89.9% by mass of at least one organopolysiloxane A comprising at least one (meth)acrylate group;

[0490] -from 10 to 50% load D;

[0491] - from 0.1 to 15% by mass of at least one radical photoinitiator B which is a compound of formula (XXVI):

[0492] Formula (XXVI) in which, Rg identical or different represents:

[0493] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0494] -an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl,

[0495] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0496] -a hydroxyl group (OH),

[0497] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5,

[0498] -a group (O-Alk) xwith Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,

[0499] -an acrylate or meth (acrylate) group,

[0500] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0501] -an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms,

[0502] - a carbonyl or carboxyl group,

[0503] -a hydrogen,

[0504] -a grouping of formula (XXVII):

[0505] 0Formula (XXVII) in which Ri and R2 represent groups as defined previously: Re represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C18.

[0506] R10 identical or different represents:

[0507] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0508] -an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl,

[0509] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0510] -a hydroxyl group (OH),

[0511] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5,

[0512] -a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,

[0513] -an acrylate or meth(acrylate) group, -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0514] -an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms,

[0515] -a carbonyl or carboxyl group,

[0516] -a hydrogen;

[0517] Ru represents a -CH3 group or an oxygen atom;

[0518] Z represents a -CH2- group or an oxygen atom;

[0519] Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0520] -an alkyl group of 1 to 6 carbon atoms,

[0521] -an alkenyl group of 2 to 4 carbon atoms,

[0522] -a heteroatom O, N or S,

[0523] -a halogen,

[0524] -a SiMe3 group,

[0525] -a hydroxyl group (OH),

[0526] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5; m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 100; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 100.

[0527] In a particularly preferred embodiment, said photocrosslinkable silicone composition X2 is characterized in that the radical photoinitiator B as represented by formula (XXVI) is further defined when a=1 q>0 or at least one group R9 is a hydroxyl group;

[0528] According to one embodiment, the photocrosslinkable silicone composition X2 is characterized in that the radical photoinitiator B is a compound of formula (XXVI) indicated above: in which, R9 and R™, identical or different, represent:

[0529] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0530] - a hydroxyl group (OH),

[0531] - a hydrogen atom

[0532] Ru represents a -CH3 group or an oxygen atom;

[0533] Z represents a -CH2- group or an oxygen atom;

[0534] Ar represents an aryl group of 6 carbon atoms substituted or not by at least one of the following groups:

[0535] -an alkyl group of 1 to 6 carbon atoms,

[0536] -an alkenyl group of 2 to 4 carbon atoms,

[0537] -a heteroatom O, N or S,

[0538] -a halogen,

[0539] -a SiMe3 group,

[0540] - a hydroxyl group (OH), m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 10; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 20; and when a = 1: q > 0 or at least one R9 group is a hydroxyl group;

[0541] The photocrosslinkable silicone composition X2 further comprises at least one additive.

[0542] In a preferred embodiment, the additive is a filler, a photoabsorber, or a photostabilizer, and mixtures thereof.

[0543] The X2 photocurable silicone composition can be used in a wide variety of technical fields such as printing inks, printing techniques, varnishes, wood coatings, plastic coatings, metal coatings, adhesives, and 3D printing.

[0544] It is therefore possible to use it with coating tools used to prepare non-stick silicone coatings.

[0545] The invention also relates to a method for preparing a coating on a support, comprising the following steps:

[0546] -application of a photocrosslinkable silicone composition X2 to a support, and -crosslinking of said composition by electronic or photonic irradiation, preferably by exposure to an electron beam, by exposure to gamma rays, or by exposure to radiation with a wavelength between 200 nm and 450 nm, in particular to UV radiation. Advantageously, the photoinitiator B of the photocrosslinkable composition X2 is a compound chosen from the compounds of formula: (VIII), (XIII), (XVII), (XXa), (XXb), (XXc), (XXd) and / or mixtures thereof.

[0547] Preferably, the photoinitiator B of the photocrosslinkable composition X2 is a compound chosen from the compounds of formula: (VIII), (XIII), (XVII), (XXa) and / or their mixtures.

[0548] The photocrosslinkable silicone composition X2 according to the invention without solvent, that is to say undiluted, can be applied using devices capable of depositing, in a uniform manner, small quantities of liquids. For this purpose, for example, the device called "Helio sliding" can be used, comprising in particular two superimposed cylinders: the role of the cylinder placed lowest, immersed in the coating tank where the compositions are located, is to impregnate in a very thin layer the cylinder placed highest, the role of the latter is then to deposit on the paper the desired quantities of the compositions with which it is impregnated, such a dosage is obtained by adjusting the respective speed of the two cylinders which rotate in opposite directions to each other.

[0549] Crosslinking, which results in curing of the photocurable silicone composition X2, can be carried out continuously by passing the substrate coated with the composition through irradiation equipment which is designed to provide the coated substrate with sufficient residence time to complete curing of the coating.

[0550] Preferably, the curing is carried out in the presence of the lowest possible oxygen concentration, typically at an oxygen concentration of less than 100 ppm, and preferably less than 50 ppm. The curing is generally carried out in an inert atmosphere, for example nitrogen or argon.

[0551] The exposure time required to cure X2 silicone composition varies with factors such as:

[0552] - the particular formulation used, the type and wavelength of radiation,

[0553] - the dose rate, the energy flux,

[0554] - the concentration of radical photoinitiator, and

[0555] - the atmosphere and the thickness of the coating.

[0556] These parameters are well known to those skilled in the art who will know how to adapt them.

[0557] The quantities of photocrosslinkable silicone composition X2 deposited on the supports are variable and most often range between 0.1 and 5 g / m 2 of treated surface. These quantities depend on the nature of the supports and the non-stick properties sought. They are most often between 0.5 and 1.5 g / m 2 for non-porous supports.

[0558] This process is particularly suitable for preparing a non-stick silicone coating on a support which is a flexible support made of textile, paper, polyvinyl chloride, polyester, polypropylene, polyamide, polyethylene, polyethylene terephthalate, polyurethane or non-woven glass fibers.

[0559] Flexible supports coated with a non-stick silicone coating can be, for example:

[0560] - a paper or a polymer film of the polyolefin type (polyvinyl chloride (PVC), PolyPropylene or Polyethylene) or of the polyester type (PolyEthyleneTerephthalate or PET),

[0561] - an adhesive tape whose inner face is coated with a layer of pressure-sensitive adhesive and whose outer face has the non-stick silicone coating;

[0562] - or a polymer film for protecting the adhesive side of a pressure-sensitive adhesive or self-adhesive element.

[0563] These coatings are particularly suitable for use in the field of anti-adhesion.

[0564] The invention also relates to a coated support obtainable according to the method described above. As indicated above, the support may be a flexible support made of textile, paper, polyvinyl chloride, polyester, polypropylene, polyamide, polyethylene, polyethylene terephthalate, polyurethane or non-woven glass fibers.

[0565] Coated substrates have a non-stick, water-repellent character, or allow improved surface properties such as slipperiness, stain resistance or softness.

[0566] Another subject of the invention relates to the use of a support at least partially coated with a non-stick coating according to the invention and as defined above in the field of self-adhesive labels, strips including envelopes, graphic arts, medical care and hygiene.

[0567] The invention also relates to photoinitiators of formula (XXVIII)

[0568] Formula (XXVIII) in which,

[0569] Rg identical or different represents:

[0570] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, -an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl,

[0571] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0572] -a hydroxyl group (OH),

[0573] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5,

[0574] -a group (O-Alk) xwith Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,

[0575] -an acrylate or meth (acrylate) group,

[0576] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0577] -an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms,

[0578] - a carbonyl or carboxyl group,

[0579] -a hydrogen,

[0580] -a grouping of formula (XXIX): Formula (XXIX) in which R1 and R2 represent groups as defined previously; R6 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C, Rw, identical or different, represents:

[0581] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0582] -an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl,

[0583] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0584] -a hydroxyl group (OH),

[0585] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5,

[0586] -a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,

[0587] -an acrylate or meth (acrylate) group,

[0588] -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched,

[0589] -an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms,

[0590] - a carbonyl or carboxyl group,

[0591] -a hydrogen,

[0592] Ru represents a -CH3 group or an oxygen atom;

[0593] Z represents a -CH2- group or an oxygen atom;

[0594] Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups:

[0595] -an alkyl group of 1 to 6 carbon atoms,

[0596] -an alkenyl group of 2 to 4 carbon atoms,

[0597] -a heteroatom O, N or S,

[0598] -a halogen,

[0599] -a SiMe group 3]

[0600] -a hydroxyl group (OH),

[0601] -a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 100; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 100;

[0602] Said photoinitiators being characterized in that when a = 1: q > 0 or at least one group R9 is a hydroxyl group. According to one embodiment, the invention also relates to the photoinitiators of formula (XXVIII) indicated above: in which, R9 and R™, identical or different, represent:

[0603] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0604] - a hydroxyl group (OH),

[0605] - a hydrogen atom

[0606] Ru represents a -CH3 group or an oxygen atom;

[0607] Z represents a -CH2- group or an oxygen atom;

[0608] Ar represents an aryl group of 6 carbon atoms substituted or not by at least one of the following groups:

[0609] -an alkyl group of 1 to 6 carbon atoms,

[0610] -an alkenyl group of 2 to 4 carbon atoms,

[0611] -a heteroatom O, N or S,

[0612] -a halogen,

[0613] -a SiMe3 group,

[0614] - a hydroxyl group (OH), m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 10; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 20; and when a = 1: q > 0 or at least one R9 group is a hydroxyl group;

[0615] Examples

[0616] This silicone acrylate polymer having a molecular mass M w of 7654g / mol, will be noted polymer ai in the following examples.

[0617] This silicone acrylate polymer having a molecular mass M w of 18,714 g / mol will be noted polymer a2 in the following examples.

[0618] This silicone acrylate polymer having a molecular mass M w of 18,862 g / mol will be noted polymer a3 in the following examples.

[0619] This silicone acrylate polymer having a molecular mass M w of 8297 g / mol will be noted polymer a4 in the following examples.

[0620] -sl-o-[si

[0621] This silicone acrylate polymer having a molecular mass M w of 2340g / mol will be noted polymer as in the following examples. Photoinitiator B used in the examples:

[0622] In the following examples, the Mes group designates the Mesityl group represented by the following formula:

[0623] The photoinitiator of the present invention denoted B1 has a specific molecular mass M w of 2,600g / mol.

[0624] The photoinitiator of the present invention denoted B2 has a specific molecular mass M w of 690g / mol.

[0625] The photoinitiator of the present invention denoted B3 has a specific molecular mass M w of 764g / mol.

[0626] Photoinitiator C comparison: This photoinitiator is Ethyl(2,4,6-trimethylbenzoyl)-phenylphosphinate known as TPO-L (CAS 84434-11-7) and will be noted C1 in the following examples. This comparative photoinitiator has a molecular mass M w of 316g / mol.

[0627] This photoinitiator is bis(2,4,6-trimethyl benzoyl)phenyl phosphine oxide known as BAPO (CAS 162881-26-7) and will be noted C2 in the following examples. This comparative photoinitiator has a molecular mass M w of 418g / mol.

[0628] Additives used in the examples:

[0629] Charge D1: Pyrogenic silica treated with SiMes groups on the surface with a BET specific surface area of ​​200m 2 / g

[0630] Physical and / or mechanical properties:

[0631] Viscosity: In this application, viscosity is measured by Brookfield CAP 1000+ / CAP 2000+ viscometers. These ICI type viscometers with cone-plate geometry and imposed speed allow rapid measurement, at controlled temperature, on small sample volumes. This is a characterization at high shear rate.

[0632] The viscosity of the sample is measured at 25°C according to ASTM D4287.

[0633] Hardness: The hardness of the crosslinked sample is measured at 25°C according to ASTM D2240 or ISO868.

[0634] Elongation at break and breaking strength: These two physical quantities of the crosslinked sample are measured at 25°C according to ASTM D412.

[0635] Modulus of elasticity at 100% elongation: This physical quantity of the sample is measured at 25°C according to ASTM D412.

[0636] Tear resistance: This physical quantity of the sample is measured at 25°C according to the ISO-34-2 standard using a “bean-shaped specimen”.

[0637] Sticky feel: The sticky feel of the sample is measured qualitatively at 25°C by placing the index finger on the face of the sample to be characterized. Once the index finger is placed on the face of this sample, pressure is applied to it, then the finger is removed to assess the sticky feel or not of the face of the sample.

[0638] In the above examples, the face of the sample characterized is the last layer of the sample after crosslinking.

[0639] Photocrosslinkable compositions:

[0640] In the context of the examples of the present invention, when it is desired to have a photocrosslinkable silicone composition which is stable for a long period of time, up to several months, it is then possible to add to said composition 10 to 1000 ppm of stabilizer such as 4-methoxyphenol.

[0641] Comparative photocrosslinkable composition:

[0642] Composition Ci: In the examples below, composition Ci consists of photoinitiator C1 present at X% by mass relative to the total mass of the composition. The resulting composition Ci is mixed manually for 2 minutes until the solution is clear.

[0643] Composition C2: In the examples below, composition C2 consists of photoinitiator C2 present at X% by mass relative to the total mass of the composition. The resulting composition C2 is mixed manually for 2 minutes until the solution is clear.

[0644] Photocrosslinkable compositions according to the present invention:

[0645] Composition 1: In the examples below, composition 1 consists of photoinitiator B1 present at X% by mass relative to the total mass of the composition. The resulting composition 1 is mixed manually for 2 minutes until the solution is clear.

[0646] Composition 2: In the examples below, composition 2 consists of photoinitiator B2 present at X% by mass relative to the total mass of the composition. The resulting composition 2 is mixed manually for 2 minutes until the solution is clear.

[0647] Composition 3: In the examples below, composition 3 consists of photoinitiator B3 present at X% by mass relative to the total mass of the composition. The resulting composition 3 is mixed manually for 2 minutes until the solution is clear.

[0648] Note, the mass percentage of each photoinitiator noted above X% is specified in each example of the present application.

[0649] Note that the examples according to the present invention are carried out without solvent or cosolvent to solubilize the photocrosslinkable compositions.

[0650] In the following examples, composition 1 ai will designate composition 1 implemented with polymer ai as organopolysiloxane A. Composition 1 a2 will designate composition 1 implemented with polymer a2 as organopolysiloxane A.

[0651] In the specific case where we are in the presence of a mixture of organopolysiloxane ai and as, in composition 2, it will then be noted composition 2ai+as.

[0652] The composition Cias will designate the composition Ci implemented with the polymer as as organopolysiloxane A. By analogy, compositions 1, 2 and 3 will be noted as set out above.

[0653] Materials and devices:

[0654] ASIGA Max 3D Printer is a 3D (DLP) printer: Before adding to the 1 L tank of the device (with a print volume XYZ: 1 19x67x75 mm 3 ), the photocrosslinkable compositions are mixed manually or using a mixer. A test piece with a thickness of 2mm+ / -0.1 consisting of 27 layers (i.e. 75pm per layer) is then designed by a computer program. Unless otherwise indicated, in the present application the first layer is irradiated for 20s and the following ones were irradiated for a duration of 5s for each layer at 385nm and at an energy defined in the examples.

[0655] The Anycubic Photon Mono 6K printer is a (LCD) 3D printer: In this case, the light coming from a set of 405nm LEDs is projected through an LCD screen which acts as a mask revealing only the pixels necessary to print the model.

[0656] Before adding 11 to the tank of the device (with a print volume XYZ 192x120x245 mm 3 ) the photocrosslinkable compositions are mixed manually or using a mixer. A test piece with a thickness of 2mm + / - 0.1 consisting of 27 layers (i.e. 75pm per layer) is then designed by a computer program. Unless otherwise indicated, in the present application the first layer is irradiated for 40s and the following ones were irradiated for a duration of 20s for each layer at 405nm and at an energy defined in the examples.

[0657] Example 1: Synthesis of photoinitiators B

[0658] The various photoinitiators of the present invention were prepared according to a preparation process analogous to those disclosed in patent application WO2014 / 053455.

[0659] Example 2: Solubility tests:

[0660] For the purpose of evaluating the solubility of the photoinitiators of the present invention, B1, B2 and B3, the photocrosslinkable compositions 1ai, 1a2, 2ai, 2a2, 3ai and 3a2 were prepared.

[0661] In parallel, the comparative photocrosslinkable compositions Ci3i and C2a2 were also prepared.

[0662] These tests were carried out at two different mass percentages. First, the photocrosslinkable compositions (1 ai, 1 a2, 2ai, 2a2, 3ai and 3a2) contain 1% by mass of photoinitiator relative to the total mass of the composition. Secondly, the photocrosslinkable compositions (1 ai and 2ai) contain 10% by mass of photoinitiator relative to the total mass of the composition.

[0663] The solubility of these different photoinitiators was observed visually with the naked eye after manual stirring of the different samples.

[0664] The table below indicates the solubility of the different photoinitiators of the present invention.

[0665] Table 1: Study of the solubility of different photoinitiators

[0666] It can be noted that the comparative photocrosslinkable compositions Ciai and Cia2 with the photoinitiator C1 are turbid at the different mass percentages indicated in the table above.

[0667] The insolubility of photoinitiator C1 in organopolysiloxanes A (ai and a2) makes its use difficult in additive manufacturing methods such as described in the present invention. The addition of a solvent may be necessary to solubilize such a system.

[0668] Indeed, turbidity is visually observed from 1% by mass of photoinitiator C1 relative to the weight of organopolysiloxane A. This turbidity increases when the mass percentage of photoinitiator C1 is increased relative to the total mass of the composition. On the other hand, the photoinitiators of the present invention B1, B2 and B3 have satisfactory solubility in the organopolysiloxanes A (ai and a2) at the different mass percentages indicated in the table above. Example 3: Study and characterization of photocrosslinkable compositions according to the present invention:

[0669] Example 3a:

[0670] Table 2: Summary table of photocrosslinkable compositions used:

[0671] The molar quantity of phosphorus atom present in the photocrosslinkable composition allows an approximation to be made on the quantity of active species material in the photocrosslinkable composition studied.

[0672] Thus, it is noted that the photocrosslinkable composition of the present invention of Example 3 has a low amount of active species material compared to the comparative composition Cia2.

[0673] Example 3b: Depth of crosslinking of a photocrosslinkable composition according to the process of the invention.

[0674] In this example, the organopolysiloxane A used in the various photocrosslinkable compositions is polymer a2.

[0675] This example aims to compare the crosslinking depth of a photocrosslinkable composition according to the present invention (2a2) and a comparative photocrosslinkable composition (Cia2) as described in Table 2.

[0676] Table 3 below shows the crosslinking depth values ​​for the different photocrosslinkable compositions depending on the energy used (5mW / cm 2 or 11 mW / cm 2). Table 3: Measurement of crosslinking depths (pm) It is noted that at low light intensity a greater depth of crosslinking is obtained with the photocrosslinkable composition 2a2 of the present invention than with the comparative composition Cia2.

[0677] Under these conditions, it was observed that at 5mW / cm 2 the gel point (a measurable non-liquid thickness) is reached for the photocrosslinkable composition 2a2 after 12s, whereas for the comparative photocrosslinkable composition Cia2 the gel point only occurs after 18s.

[0678] Example 3b: Evaluation of the mechanical properties of the test piece obtained according to the method of the invention (without adding load):

[0679] The physical and mechanical properties of the test pieces produced according to the process of the invention from the photocrosslinkable compositions of example 3a could be tested.

[0680] These properties were tested at two different energy values, namely 5mW / cm 2 and 1 1 mW / cm 2 .

[0681] The 3D printer used is the ASIGA Max at 385nm; the first layer is irradiated for 80s and each of the following layers is irradiated for 20s to obtain a test specimen and to be able to carry out the evaluation of the mechanical properties.

[0682] Table 4 below lists the mechanical and physical properties such as elongation at break, tensile strength, modulus of elasticity at 100%, hardness and tack of the specimen at different energy values. The mechanical property values ​​shown are an average of results obtained for measurements carried out on 4 separate specimens printed simultaneously.

[0683] Table 4: Measurement of mechanical and physical properties of the different test pieces

[0684] It can be deduced from Table 4 above that the two test pieces produced according to the method of the invention have satisfactory mechanical properties.

[0685] Furthermore, it is observed that the test piece obtained according to the method of the invention does not have a sticky feel unlike the comparative test piece Cia2. The non-sticky feel property makes it possible to limit the post-treatment steps before a subsequent application of the test piece obtained according to the method of the invention.

[0686] Example 4: Study and characterization of a photocrosslinkable composition of the present invention:

[0687] Example 4a:

[0688] Table 5: Summary table of photocrosslinkable compositions used:

[0689] The molar quantity of phosphorus atom present in the photocrosslinkable composition allows an approximation to be made on the quantity of active species material in the photocrosslinkable composition studied.

[0690] Thus, it is noted that the photocrosslinkable composition of the present invention of Example 4 has a low amount of active species material compared to the comparative compositions Cia3 and C2a3.

[0691] Example 4b: Evaluation of crosslinking depth of photoinitiators of the present invention:

[0692] In this example, the organopolysiloxane A used in the different photocrosslinkable compositions is polymer a3. This example aims to compare the crosslinking depth of photocrosslinkable compositions of the present invention (1 a3 and 2a3) and a comparative photocrosslinkable composition (Cia2) as described in Table 5. Table 6: Measurement of crosslinking depth values ​​for the different compositions as a function of the energy used (5mW / cm 2 , 1 1 mW / cm 2 or 21 mW / cm 2 ).

[0693]

[0694] We then note that the comparative photocrosslinkable composition C2a3(BAPO) does not lead to any crosslinking.

[0695] In contrast, the photocrosslinkable compositions of the present invention 1a3(photoinitiator B1) and 2a3(photoinitiator B2) exhibit satisfactory crosslinking depth as does the comparative composition Cia3(TPO-L).

[0696] Example 4c: Evaluation of the mechanical properties of the specimen obtained by 3D printing without adding load:

[0697] The physical and mechanical properties of the test pieces produced according to the process of the invention from the photocrosslinkable compositions of Example 4a could be tested. As a reminder, the photocrosslinkable composition 2a3 indicated in the table below has a mass percentage of photoinitiator of 0.5% by mass relative to the total mass of the composition. The photocrosslinkable compositions 1a3, C1a3 and C2a3 contain 0.7% by mass of photoinitiator relative to the total mass of the composition.

[0698] The 3D printer used is the ASIGA Max at 385nm; the first layer is irradiated for 80s and each of the following layers is irradiated for 20s to obtain a test specimen and to be able to carry out the evaluation of the mechanical properties.

[0699] In this test, overexposure is deliberately used to obtain total conversion of the acrylates and to preliminary evaluate the photoinitiator system.

[0700] Table 7 below mentions the mechanical and physical properties like elongation at break, breaking strength, modulus of elasticity at 100%, hardness and tackiness of the specimen at an energy of 11 mW / cm 2 The mechanical property values ​​indicated are an average of the results obtained for measurements carried out on at least 3 separate specimens printed simultaneously.

[0701] Table 7 above shows that the comparative photocrosslinkable composition C2a3(BAPO) does not lead to obtaining a test piece with satisfactory mechanical properties.

[0702] On the other hand, the photocrosslinkable compositions of the present invention 1 a3 (photoinitiator B1) and 2a3 (photoinitiator B2) make it possible to obtain test pieces having satisfactory mechanical properties, just like the test piece resulting from the comparative composition Cia3 (TPO-L).

[0703] It is also observed that the test piece obtained according to the method of the invention does not have a sticky feel unlike the comparative test pieces.

[0704] Example 5: Evaluation of crosslinking depth of photoinitiators of the present invention at very low energy at 405nm (1.5mW / cm 2 at 3.8mW / cm 2 ) Example 5a:

[0705] Table 8: Summary table of photocrosslinkable compositions used:

[0706] The molar quantity of phosphorus atom present in the photocrosslinkable composition allows an approximation to be made on the quantity of active species material in the photocrosslinkable composition studied.

[0707] Thus, it is noted that the photocrosslinkable composition of the present invention of Example 5 has a low amount of active species material compared to the comparative composition Cia3.

[0708] In this example, the organopolysiloxane A used in the various photocrosslinkable compositions is polymer a3. This example shows the activity of the photoinitiators B2 and B3 defined in the present invention at a wavelength of 405nm, and therefore at very low energy.

[0709] The 3D printer used is the UV-LED (Anycubic Photon Mono 6k) at 405nm; the first layer is irradiated for 80s and each of the following layers is irradiated for 20s to obtain a test specimen.

[0710] Table 9: Measurement of crosslinking depth values ​​for the different compositions depending on the energy used (1.5mW / cm 2 , 2.6mW / cm 2 or 3.8mW / cm 2 ).

[0711] These tests clearly demonstrate the activity of the photocrosslinkable compositions of the present invention at very low energy and at very low molar concentration of photoinitiator.

[0712] Example 6: Study of the mechanical properties of a 3D printed specimen formulation with filler: In this example, the organopolysiloxane A used in the different photocrosslinkable compositions is the combination of polymer a1 and a3.

[0713] This example aims to measure the mechanical properties of a test piece according to the method of the invention containing 22 to 30% of D1 filler. The formulations prepared under the conditions of Table 10 below were introduced into the Asiga 3D printer equipped with a UV-LED with a wavelength of 385nm.

[0714] The 3D printed specimens in this example according to the formulas set out below were produced at an energy of 11 mW / cm 2 The 3D specimen was printed with 27 layers, each 75 microns thick.

[0715] Table 10: Summary table of the different photocrosslinkable compositions used:

[0716] The viscosity of the formulations having 22 to 30% silica presented in the table above were measured according to the protocol described below.

[0717] After manual mixing of these formulations for 5 minutes the viscosities of these formulations were measured after a rest time of at least one hour by a Brookfield Cap 2000 viscometer with cone-plate geometry (cone 6) as mentioned in table 11 below.

[0718] Table 1 1: Measurement of the viscosity of the different formulations used:

[0719]

[0720] The comparative formulation Ciai+a3 comprising 22 to 30% of D1 filler has a high viscosity at low shear rate (<20s -1 ) and leads to the impossibility of producing a test piece by 3D printing under these conditions. Indeed, the maximum viscosity accepted by the ASIGA-DLP printer is 15,000 mPa.s with a special tank supplied by the manufacturer adapted (SG-MAX-TRAY-1 L-LF) with low detachment force for high viscosities at low shear rate <20s-1.

[0721] This mismatch also applies to other additive manufacturing techniques such as laser stereolithography (SLA) printing or continuous liquid interface production (CLIP) printing or printing through a liquid crystal display (LCD) screen.

[0722] On the other hand, the formulations of the present invention, 2ai+a3 and 3ai+a3, comprising the photoinitiators B2 and B3 are compatible for producing a test piece by 3D printing at high load values ​​such as 25 or even 30% by mass of load D1 relative to the total mass of the formulation.

[0723] The table below lists the mechanical and physical properties such as elongation at break, breaking strength, modulus of elasticity at 100%, hardness and stickiness of the specimen made from a specimen comprising 22%, 25 or 30% D1 load at an energy of 11 mW / cm 2 .

[0724] Table 12: Table of mechanical properties associated with these formulations:

[0725] The acronym "N. A" mentioned in the table above means that this is not applicable for the comparative specimen C1ai+a3. Indeed, the high viscosity of the comparative formulation 0ai+a3 does not allow additive manufacturing of the specimen.

[0726] On the contrary, the formulations defined according to the process of the invention allow the production of 3D printed specimens with satisfactory mechanical properties as evidenced by the data in table 12 above.

[0727] Furthermore, it is observed that the presence of filler makes it possible to considerably improve the mechanical and physical properties of the test pieces obtained according to the method of the invention.

[0728] In particular, it is observed that from 30% load D1 the test piece obtained according to the method of the invention has improved tear resistance properties compared to the other test pieces.

[0729] This mechanical property is satisfactory enough to allow for the consideration of new fields of application for this formulation and the 3D printing of functional objects obtained according to the process of the invention.

[0730] Finally, it is also observed that the test pieces obtained according to the method of the invention do not have a sticky feel unlike the comparative test pieces. _ Example 7: Study of the mechanical properties of a formulation of 3D printed tensile test pieces with very low energy load (405nm):

[0731] In this example, the formulation 2ai+a3 (containing 30% of D1 filler) defined in Table 7 was studied at 3.8mW / cm 2This example aims to demonstrate that at a wavelength of 405nm, the method according to the invention is capable of providing test pieces having satisfactory mechanical properties.

[0732] In this example, the first layer of the specimen was irradiated for 20s and the following ones were irradiated for 5s each, at a wavelength of 405nm and an energy of 3.8mW / cm 2 .

[0733] The table below indicates the mechanical properties of the test piece obtained according to the method of the invention at an energy of 3.8mW / cm 2

[0734] Table 13: Mechanical properties of the specimen obtained according to the method of the invention at an energy of 3.8mW / cm 2

[0735] As a reminder, the comparative formulation Ciai+a3 with 30% D1 filler has a high viscosity and does not allow additive manufacturing of specimens.

[0736] On the other hand, we can conclude that at 3.8mW / cm 2 and with a high D1 load value (30%), the mechanical properties of the test piece obtained according to the method of the invention are satisfactory.

[0737] Example 8: Measurement of the “yellowing” effect of a test piece obtained according to the method of the invention

[0738] Table 14: Measurement of the 'yellowing' effect of a test piece obtained according to the method of the present invention

[0739] The various photocrosslinkable compositions mentioned in the table above have a mass percentage of photoinitiator of 1% relative to the total mass of the photocrosslinkable composition. In the context of this example, the “yellowing” effect of a test piece obtained according to the process of the invention is studied. The test piece obtained according to the process of the invention is compared to a test piece obtained from the comparative photocrosslinkable composition Cia2 which has satisfactory “photobleaching” properties.

[0740] To do this, a CIELAB standard test is carried out to evaluate the “yellowing” effect of these different test pieces.

[0741] The table above mentions the values ​​of the quantities L, a and b of the different test pieces obtained from the photocrosslinkable compositions.

[0742] These quantities correspond to the different XYZ axes presented in figure 1 in the appendix.

[0743] Thus, it is observed that the test piece obtained from the photocrosslinkable composition 2a2, according to the process of the invention, has magnitudes L, a and b similar to those of the comparative photocrosslinkable composition Cia2.

[0744] It can therefore be concluded that the photocrosslinkable composition 2a2 of the invention has satisfactory “photobleaching” properties.

[0745] Example 9: Tests on supports coated with non-stick silicone coatings:

[0746] In this example, the photocrosslinkable composition Invi consists of a mixture of polymer a and a polymer a5 and 0.8% by mass of photoinitiator B3 relative to the total mass of the photocrosslinkable composition in the following examples. Similarly, a comparative composition Compi consists of a mixture of polymer a and a polymer a5 and 0.8% by mass of photoinitiator Ci relative to the total mass of the photocrosslinkable composition.

[0747] These two aforementioned compositions were studied at 11.5 mW / cm 2 .

[0748] Tests carried out on supports coated with non-stick silicone coatings:

[0749] Smear: Qualitative control of surface polymerization by the finger trace method which consists of:

[0750] - Place the silicone-coated support sample to be tested on a flat, rigid surface;

[0751] - Make a mark with the tip of your finger, pressing moderately but clearly; and

[0752] - Examine the trace thus made visually, preferably in raking light. The presence of even a very slight trace can be seen by the difference in surface brightness.

[0753] The assessment is qualitative. We quantify the “Smear” with the following notations:

[0754] A: Very good, no fingerprints

[0755] B: a little less good, barely visible trace

[0756] C: clear trace

[0757] D: very clear trace and oily appearance of the surface, product barely polymerized, i.e. a grade from A to D, from the best result to the worst.

[0758] Rub-off: Checking the silicone's ability to adhere to the flexible support by rubbing it back and forth with the finger, which consists of:

[0759] - Place the silicone-coated support sample to be tested on a flat, rigid surface, with the silicone on the upper side

[0760] - Make 10 back and forth (AR) movements with the tip of your finger (over a length of approximately 10 cm) pressing moderately but clearly.

[0761] - Visually examine the appearance of the scrub. Scrubbing corresponds to the appearance of a fine white powder or small balls that roll under the finger.

[0762] The assessment is qualitative. The scrubbing is quantified with the following notations:

[0763] • 10: very good, no appearance of exfoliation after 10 AR

[0764] • 1: very bad, scrubbing on the first go

[0765] The score corresponds to the number of round trips (from 1 to 10) from which a scrub appears. That is, a score from 1 to 10, from the lowest to the best result.

[0766] Dewetting: Assessment of the degree of polymerization of the silicone layer by evaluating the transfer of silicone onto an adhesive placed in contact with the coating using a standardized surface tension ink. The method is as follows:

[0767] - Select a sample of approximately 20 x 5 cm of the silicone-coated paper to be characterized, taken in the unwinding direction (machine direction). - Cut a length of » 15 cm of adhesive tape, then place it adhesive side down on the paper to be tested, without folds, exerting pressure 10 times by sliding your finger along the length of the adhesive tape. (3M “Scotch” adhesive tape, reference 610, width: 25 mm).

[0768] - Remove the adhesive tape and lay it flat, adhesive side up.

[0769] - Place a trace of ink on the adhesive part of the tape, using a cotton swab (disposable), over a length of approximately 10 cm (SHERMAN or FERARINI and BENELI brand inks with a surface tension of 30 dynes / cm and a viscosity of 2 to 4 mPa / s). Immediately start the stopwatch.

[0770] - We consider that we are entering the dewetting phase when the ink line changes appearance, then stop the stopwatch.

[0771] - The ink must be applied to the adhesive part of the ribbon within 2 minutes of the silicone coating.

[0772] - If the result obtained is < 10 seconds, it is considered that there is migration of silicone onto the adhesive, and that polymerization is not complete.

[0773] - A score from 0 to 10 will be given corresponding to the time elapsed in seconds before the dewetting phenomenon is observed.

[0774] - If the result obtained is 10 seconds, it is considered that the polymerization is complete. In this case, a score of 10 will be given, meaning that the result is very good.

[0775] - Note the score obtained and the ink used (name, brand, surface tension, viscosity).

[0776] Extractables: Measure of the amount of silicone that is not grafted to the network formed during polymerization. These silicones are extracted from the film by immersing the sample immediately after the machine exits in the MIBK for at least 24 hours. This is measured by flame absorption spectroscopy. The extractables rate must be kept below 8% and preferably below 6%. The results of the various industry tests are presented in the following table.

[0777] Table 15: Results of trade tests on coatings

[0778] The trade tests of the formulation comprising the photoinitiator B3 of the present invention are satisfactory. There is no degradation of the properties of the coating obtained. Release: Peel force measurements were carried out with the TESA 7475 standard adhesive on the support coated with silicone coating. The test pieces of the multilayer article (adhesive in contact with silicone surface) were stored for 1 day at 23°C (FINAT 3 - FTM 3), 1 day at 70°C (FINAT 10 - FTM 10), 7 days at 40°C under the required pressure conditions, then tested at low peel speed according to the tests mentioned above and known to those skilled in the art.

[0779] The peel force is expressed in cN / inch and is measured using a dynamometer, after pressurizing the samples either at room temperature (23°C) or at a higher temperature for accelerated aging tests.

[0780] The results are presented in Table 16 below.

[0781] Table 16: Peeling force in cN / inch

[0782] It is observed that the detachment forces obtained with the formulation of the present invention are satisfactory, in particular after aging.

[0783] Subsequent adhesion or “Subsequent adhesion” (“SubAd” in the tables): Verification measurement of the retention of adhesiveness of adhesives (TESA 7475) having been in contact with the silicone coating according to the FINAT 11 (FTM 11) test known to those skilled in the art. Here the reference test piece is PET and the adhesives remained in contact with the silicone surface to be tested for 7 days at 40°C.

[0784] The results are expressed in % of retention of adhesive force of the reference tape: CA = (Fm2 / Fm1) x 100 in % with:

[0785] Fm2 = Average tape peeling forces after 20 h contact with silicone support; and Fm1 = Average tape peeling forces without contact with silicone support.

[0786] The results are recorded in Table 17 below.

[0787] Table 17: Subsequent membership (in %)

[0788] Thus, with the formulation of the present invention the subsequent adhesion measurement is very satisfactory even after aging. Indeed, there is no loss of the adhesiveness of the adhesive brought into contact with the silicone coating.

Claims

Claims 1. Additive manufacturing method for producing a silicone elastomer article, said method comprising the following steps: i) implementing a photocrosslinkable silicone composition X and an irradiation source, said photocrosslinkable silicone composition X comprising: a) at least one organopolysiloxane A comprising at least one (meth)acrylate group b) at least one radical photoinitiator B represented by the formula (I): Formula (I) in which, R represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably a linear or branched C1-C18 group, said alkylene and heteroalkylene groups comprising at least one siloxane function; Ri represents a group of formula (II): Formula (II) in which Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups: - an alkyl group of 1 to 6 carbon atoms, - an alkenyl group of 2 to 4 carbon atoms, - a heteroatom O, N or S, - a halogen, - a SiMe3 group, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5; R2 represents: - a Ri group - an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups: - an alkyl group of 1 to 6 carbon atoms, - an alkenyl group of 2 to 4 carbon atoms, - a heteroatom O, N or S, - a halogen, - a SiMe3 group, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5; ii) Selectively irradiating at least a portion of the photocrosslinkable silicone composition X by means of the irradiation source to form a portion of the silicone elastomer article; and iii) Repeating step ii) a sufficient number of times to produce the silicone elastomer article.

2. Method according to claim 1, in which the radical photoinitiator B is a compound of formula (VIII): Formula (VIII) in which, R1 and R2 represent the groups as defined according to claim 1; R3 represents a linear or branched C1-C6 alkylene or heteroalkylene group; R4 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably a linear or branched C1-C18 group, said R4 comprising at least one siloxane function.

3. Method according to any one of the preceding claims, in which the radical photoinitiator B is a compound of formula (XIII): in which, Rs identical or different represents: - an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl, - an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, - an acrylate or meth(acrylate) group, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, - a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200, - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched, - a hydrogen, - a grouping of formula (XIV): Formula (XIV) in which R 1 and R 2 represent groups as defined according to claim 1; R6 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C; a represents an integer between 0 and 100; said method being characterized in that at least one group R5 is represented by the group of formula (XIV).

4. Method according to any one of the preceding claims, in which the radical photoinitiator B is a compound of formula (XV): Formula (XV) in which, R? identical or different represents: - an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl; - an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl; - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, - a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200, - an acrylate or meth(acrylate) group, - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched, - a hydrogen; R8 represents a group as defined for R? or a group of formula (XVI): Formula (XVI) in which R1 and R2 represent groups as defined according to claim 1; R6 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C18; a represents an integer between 0 and 10; b represents an integer between 1 and 100; said method being characterized in that at least one group R8 is represented by the group of formula (XVI).

5. Method according to any one of the preceding claims, in which the radical photoinitiator B is a compound of formula (XVII): Formula (XVII) in which, R9same or different represents: - an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl; - an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl; - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, - a group (O-Alk)x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200, - an acrylate or meth(acrylate) group, - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched, - an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms, - a carbonyl or carboxyl group, - a hydrogen, - a grouping of formula (XVIII): in which R1 and R2 represent groups as defined according to claim 1; R6 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably a linear or branched C1-C18 alkylene or heteroalkylene group; R10 identical or different represents: - an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl, - an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, - a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200, - an acrylate or meth (acrylate) group, - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched, - an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms, - a carbonyl or carboxyl group, - a hydrogen, R11 represents a -CH3 group or an oxygen atom; Z represents a -CH2- group or an oxygen atom; Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups: - an alkyl group of 1 to 6 carbon atoms, - an alkenyl group of 2 to 4 carbon atoms, - a heteroatom O, N or S, - a halogen, - a SiMe3 group, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5; m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 100; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 100.

6. Method according to any one of the preceding claims, in which the radical photoinitiator B and the organopolysiloxane A are one and the same molecule denoted AB.

7. A method according to any preceding claim, wherein compound AB is a compound of formula (XXa), (XXb), (XXc) or (XXd): in which, R12, identical or different, represents a hydrogen atom or a hydroxyl group. R13 identical or different represents: - an alkenyl function of 2 to 4 carbon atoms, - a group of formula (XXI), Formula (XXI) and at least one group R13 represents a group of formula (XXI). Ri and R2 represent the groups as defined according to claim 1; R14 represents: an alkyl group of 1 to 5 carbon atoms or alkenyl group of 2 to 5 carbon atoms: - substituted or not by at least one heteroatom O, N or S, - substituted or not by at least one alkyl group of 1 to 5 carbon atoms, - substituted or not by at least one aryl group of 6 to 18 carbon atoms, - xi is an integer between 1 and 1000; preferably xi is between 1 and 500; - ni is an integer between 1 and 100, preferably between 2 and 50; - x2 is an integer between 1 and 1000, preferably x2 is between 1 and 500; - n2 is an integer between 0 and 100, preferably n2 is between 0 and 50; - X3 is an integer between 1 and 1000, preferably X3 is between 1 and 500; - n3 is an integer between 0 and 100, preferably n3 is between 0 and 50 - X4 is an integer between 1 and 1000, preferably X3 is between 1 and 500; and - n4 is an integer between 0 and 100, preferably n3 is between 0 and 50; - mi, m2, m3 and m4 are integers between 1 and 8.

8. Method according to any one of the preceding claims, characterized in that the photocrosslinkable composition X further comprises a filler D.

9. Method according to any one of the preceding claims, characterized in that the photocrosslinkable composition X further comprises a photoabsorber E, or a photostabilizer F, and their mixtures.

10. Method according to any one of the preceding claims, characterized in that the molecular mass by weight of the radical photoinitiator B is between 400 and 10,000 g / mol, preferably between 400 and 5,000, preferentially between 400 and 3,000, even more preferentially between 400 and 2,600 g / mol.

11. Method according to any one of the preceding claims, characterized in that the mass percentage of radical photoinitiator B is between 0.1 and 20% relative to the total mass of the photocrosslinkable composition X, preferably between 0.1 and 5%, preferentially between 0.2 and 2%, more preferentially between 0.4 and 1.5% relative to the total mass of the photocrosslinkable composition X.

12. Method according to any one of the preceding claims, characterized in that the additive manufacturing is a technology chosen from the group consisting of printing by laser stereolithography (SLA), by digital light processing (DLP), by liquid crystal display (LCD), by continuous liquid interface production (CLIP).

13. Photocrosslinkable silicone composition X2 comprising: - from 10 to 99.9% by mass of at least one organopolysiloxane A comprising at least one (meth)acrylate group; - from 0.1 to 20% by mass of at least one radical photoinitiator B which is a compound of formula (I): Formula (I) in which, R represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably linear or branched C1-C, said alkylene and heteroalkylene groups comprising at least one siloxane function; Ri represents a group of formula (II): Formula (II) in which Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups: - an alkyl group of 1 to 6 carbon atoms, - an alkenyl group of 2 to 4 carbon atoms, - a heteroatom O, N or S, - a halogen, - a SiMes group, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5; R2 represents: - a Ri group, - an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups: - an alkyl group of 1 to 6 carbon atoms, - an alkenyl group of 2 to 4 carbon atoms, - a heteroatom O, N or S, - a halogen, - a SiMe3 group, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5.

14. Method for preparing a coating on a support, comprising the following steps: - application of a photocrosslinkable silicone composition X2 on a support, and - crosslinking of said composition by electronic or photonic irradiation, preferably by exposure to an electron beam, by exposure to gamma rays, or by exposure to radiation with a wavelength between 200 nm and 450 nm, in particular to UV radiation.

15. Photoinitiators of formula (XXVIII): Formula (XXVIII) in which, R9same or different represents: - an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl, - an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, - a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200, - an acrylate or meth(acrylate) group, - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched, - an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms, - a carbonyl or carboxyl group, - a hydrogen, - a grouping of formula (XXIX): Formula (XXIX) in which R 1 and R 2 represent groups as defined according to claim 1; R6 represents a linear or branched C1-C50 alkylene or heteroalkylene group, preferably a linear or branched C1-C50, Rw identical or different represents: - an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl, - an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, - a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200, - an acrylate or meth (acrylate) group, - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, substituted by at least one fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl being linear or branched, - an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms, - a carbonyl or carboxyl group, - a hydrogen, Ru represents a -CH3 group or an oxygen atom; Z represents a -CH2- group or an oxygen atom; Ar represents an aryl group of 6 to 18 carbon atoms substituted or not by at least one of the following groups: - an alkyl group of 1 to 6 carbon atoms, - an alkenyl group of 2 to 4 carbon atoms, - a heteroatom O, N or S, - a halogen, - a SiMe3 group, - a hydroxyl group (OH), - a group (O-Alk) with Alk representing an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably CH3 or C2H5, m represents a natural number between 1 and 8; p represents a natural number equal to 0 or 1; q represents a natural number between 0 and 100; a represents a natural number equal to 1 or 2; b represents a natural number between 0 and 100; said photoinitiators being characterized in that when a = 1: q> 0 or at least one group R9 is a hydroxyl group.

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