Method for additive manufacturing of silicone elastomer articles

Abstract

The present invention relates to a method for additive manufacturing of silicone elastomer articles using a 3D printer. The present invention also relates to a crosslinkable silicone composition for additive manufacturing of silicone elastomer articles.

Description

[Technical field]

[0001] The present invention relates to a method for additive manufacturing of silicone elastomer articles using a 3D printer. The present invention also relates to a crosslinkable silicone composition for additive manufacturing of silicone elastomer products. [Background technology]

[0002] Additive manufacturing techniques span a variety of technologies that share a common feature: the automated additive build-up of layers of a molded part. Crosslinked silicone compositions are already used in additive manufacturing processes to produce three-dimensional elastomeric silicone articles or parts. Summary of the Invention [Problem to be solved by the invention]

[0003] However, printing silicone elastomer articles with a height of at least 5 cm and complex geometries such as protruding structures or cavities is sometimes complicated. Various approaches have been used to print these types of articles. US Patent Application Publication No. 2015 / 0028523 discloses a method for printing 3D parts in an additive manufacturing system using a support material comprising a polyglycolic acid polymer. However, the support material needs to be heated to very high temperatures (above 150° C.) in order to print.

[0004] WO 2018 / 206689 discloses a silicone composition containing a thixotropic agent that can be used in 3D printing. However, the use of a thixotropic agent can result in loss of reactivity due to possible interactions with the catalyst. Thus, the crosslinking rate can be reduced.

[0005] These approaches still suffer from several drawbacks, and there is a need to provide improved methods for 3D printing silicone elastomeric articles.

[0006] It is therefore an essential object of the present invention to provide a method for additive manufacturing of silicone elastomeric articles. Another essential object of the present invention is to provide a method for additive manufacturing of silicone elastomeric articles, which method is easy to carry out.

[0007] Another essential object of the present invention is to provide a silicone composition which can be used in a process for additive manufacturing of silicone elastomeric articles.

[0008] Another essential object of the present invention is to provide a silicone composition having good reactivity. [Means for solving the problem]

[0009] These objects are in particular achieved by the present invention, which relates firstly to a method for the additive manufacturing of silicone elastomeric articles using a 3D printer, selected from an extrusion 3D printer and a 3D injection printer, said method comprising: 1) printing a crosslinkable silicone composition X onto a substrate to form a first layer; 2) printing said crosslinkable silicone composition X onto said first or previous layer to form a subsequent layer; 3) optionally repeating step 2); and 4) crosslinking the first and subsequent layers, optionally by heating, to obtain a silicone elastomeric article; Including, The crosslinkable silicone composition X comprises: - (A) at least one organopolysiloxane compound A containing per molecule at least two C2-C6 alkenyl radicals bonded to silicon atoms; - (B) at least one organohydrogenopolysiloxane compound B containing per molecule at least two hydrogen atoms bonded to identical or different silicon atoms; - (C) at least one catalyst C comprising at least one metal or compound from the platinum group; - (D) at least one thixotropic agent D selected from organosilicon compounds containing at least one cyclic amine functional group per molecule; (E) at least one filler E; and (F) optionally at least one crosslinking inhibitor F; Including, The crosslinkable silicone composition X is characterized by having a nitrogen content of 0.003 to 0.02% by weight, preferably 0.004 to 0.017% by weight, and more preferably 0.0045 to 0.016% by weight.

[0010] The present invention also relates to silicone elastomeric articles obtained by the methods described herein.

[0011] The present invention also relates to a crosslinkable silicone composition X, which comprises: - (A) at least one organopolysiloxane compound A containing per molecule at least two C2-C6 alkenyl radicals bonded to silicon atoms; - (B) at least one organohydrogenopolysiloxane compound B containing per molecule at least two hydrogen atoms bonded to identical or different silicon atoms; - (C) at least one catalyst C comprising at least one metal or compound from the platinum group; - (D) at least one thixotropic agent D selected from organosilicon compounds containing at least one cyclic amine functional group per molecule; (E) at least one filler E; and (F) optionally at least one crosslinking inhibitor F; Including, The crosslinkable silicone composition X has a nitrogen content of 0.003 to 0.02% by weight, preferably 0.004 to 0.017% by weight, and more preferably 0.0045 to 0.016% by weight.

[0012] The present invention also relates to silicone elastomer articles obtained by crosslinking the crosslinkable silicone composition X.

[0013] The present invention also relates to the use of the crosslinkable silicone composition X for the additive manufacturing of silicone elastomeric articles using a 3D printer selected from an extrusion 3D printer and a 3D injection printer.

[0014] The present invention also relates to a compound represented by the formula (D7) [ka] Regarding the organopolysiloxanes: where: - each R symbol is the same or different and represents a monovalent hydrocarbon radical selected from the group consisting of linear or branched alkyl radicals having 1 to 6 carbon atoms, the phenyl radical, and the 3,3,3-trifluoropropyl radical; - each X 1 The symbols may be the same or different and represent an alkenyl radical having 2 to 6 carbon atoms; Z is a group of formula (I) [ka] represents a group having a sterically hindered piperidinyl group; where: - R 1 is a linear or branched alkylene radical having 2 to 18 carbon atoms; an alkylenecarbonyl radical having a linear or branched alkylene moiety of 2 to 20 carbon atoms; an alkylenecyclohexylene radical having a linear or branched alkylene moiety of 2 to 12 carbon atoms and a cyclohexylene moiety containing an -OH group and, optionally, one or two alkyl radicals having 1 to 4 carbon atoms; 4 -OR 5 - radical, R 4 and R 5 The radicals are the same or different and represent alkylene radicals having 1 to 12 carbon atoms; 4 -OR 5 - radical, R 4 and R 5Radicals have the above meanings, one or both of which are substituted by one or two OH groups; radicals of the formula -R 4 -COO-R 5 -and-R 4 -OCO-R 5 - radical, R 4 and R 5 is a radical having the above meaning; or a group of the formula -R 6 -OR 7 -O-CO-R 8 - radical, R 6 , R 7 and R 8 are the same or different and represent alkylene radicals having 2 to 12 carbon atoms; R 7 The radical is an optionally hydroxyl substituted radical; - U may be present or absent, and if present, U is -O- or -NR 9 - represents R 9 is a hydrogen atom; a linear or branched alkyl radical having 1 to 6 carbon atoms; a divalent radical -R as defined above 1 -, where one valence bond is -NR 9 - a radical connected at one end to a nitrogen atom of - and at the other end to a silicon atom; or [ka] is a divalent radical of: Here, R 1 has the above meaning, R 2 and R 3 has the following meaning, R 10 represents a linear or branched alkylene radical having 1 to 12 carbon atoms and one of the valence bonds (R 10 The bond is -NR 9 - is bonded to the nitrogen atom of the other (R 1 bond) is bonded to a silicon atom; Each R 2 are the same or different and are derived from a linear or branched alkyl radical having 1 to 3 carbon atoms or a phenyl radical; R 3is a hydrogen atom or R 2 Represents radical; - m is between 0 and 2,000, preferably between 0 and 1,500, and n is between 1 and 50, preferably between 1 and 20. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] In this disclosure, the symbol "wt.%" stands for percent by weight and ppm stands for parts per million.

[0016] Additive manufacturing methods The present invention relates first to a method for additive manufacturing of silicone elastomer articles using a 3D printer selected from an extrusion 3D printer and a 3D injection printer, said method comprising: 1) printing a crosslinkable silicone composition X onto a substrate to form a first layer; 2) printing a crosslinkable silicone composition X onto the first or previous layer to form a next layer; 3) optionally repeating step 2); and 4) Crosslinking the first and subsequent layers, optionally by heating, to obtain a silicone elastomeric article. Includes.

[0017] 3D printing is commonly associated with a number of related technologies used to manufacture physical objects from computer-generated, e.g., computer-aided design (CAD), data sources.

[0018] This disclosure generally incorporates ASTM designation F2792-12a, "Standard Terminology for Additive Manufacturing Technologies."

[0019] A "3D printer" is defined as "a machine used for three-dimensional printing" and "3D printing" is defined as "the production of an object by the deposition of material using a print head, nozzle, or another printer technology."

[0020] "Additive manufacturing (AM)" is defined as "the process of fabricating objects from 3D model data by combining materials, usually layer by layer, as opposed to subtractive manufacturing methodologies. Related and included synonyms of 3D printing include additive fabrication, additive process, additive technique, additive layer manufacturing, layer manufacturing, and freeform fabrication." Additive manufacturing (AM) is also known as rapid prototyping (RP). As used herein, "3D printing" is generally interchangeable with "additive manufacturing" and vice versa.

[0021] "Printing" is defined as the deposition of a material, here a crosslinkable silicone composition, using a printhead, nozzle, or another printer technology.

[0022] In this disclosure, "3D or three-dimensional article, object or part" refers to an article, object or part obtained by additive manufacturing or 3D printing as disclosed above.

[0023] In the first step, a layer of crosslinkable silicone composition X is printed onto a substrate so that the layer is formed on the substrate. The substrate is not limited and may be any substrate. The substrate can support the 3D article during its manufacturing process, for example as a substrate plate of a 3D printer. The substrate can be rigid or flexible, continuous or discontinuous. The substrate itself may be supported, for example by a substrate table or plate, so that the substrate does not need to be rigid. It may also be removed from the 3D article. Alternatively, the substrate can be physically or chemically bonded to the 3D article. In one embodiment, the substrate may be silicone.

[0024] The layer formed by printing the crosslinkable silicone composition X can have any shape and any dimensions. The layer can be continuous or discontinuous.

[0025] In a second step, a subsequent layer is formed on the previous layer formed in the first step by printing the crosslinkable silicone composition X with an extrusion 3D printer or a material 3D jetting printer. The extrusion 3D printer and the material 3D jetting printer may be the same or different from the extrusion 3D printer or the material 3D jetting printer used in step 1).

[0026] The subsequent layers formed by printing the crosslinkable silicone composition X can have any shape and any dimensions. The subsequent layers can be continuous or discontinuous.

[0027] In a third step, the second step is repeated to obtain the required number of layers, advantageously between 10 and 1,000, preferably between 20 and 500.

[0028] In a fourth step, the layer is completely crosslinked, optionally by heating, to obtain a silicone elastomer article. Crosslinking can be completed at ambient temperature, which typically refers to a temperature of 20-25°C.

[0029] Heat may be used to accelerate crosslinking or curing of the layers. Heat curing after printing can be carried out at temperatures between 50 and 200°C, preferably 60 to 100°C, to achieve complete curing or crosslinking faster without collapse of the structure.

[0030] As used herein, the term "layer" may refer to a layer at any stage of the process, i.e., a first layer or a previous layer or a subsequent layer. Layers may have a variety of dimensions, including thickness, width, etc. The thickness of a layer may be uniform or may vary. The average thickness refers to the thickness of the layer immediately after printing.

[0031] In one embodiment, each layer independently has a thickness of from 50 to 2000 μm, preferably from 100 to 800 micrometers, and more preferably from 100 to 600 micrometers.

[0032] In certain embodiments, no energy source such as heat or radiation is applied throughout or during steps 1) through 3) prior to printing of at least 10 layers, preferably 20 layers.

[0033] In general, all 3D printing processes have a common starting point: a computer-generated data source or program that describes an object. The computer-generated data source or program can be based on a real object or a virtual object. For example, a 3D scanner can be used to scan a real object and the scan data can be used to create the computer-generated data source or program. Alternatively, the computer-generated data source or program can be designed from scratch.

[0034] The computer-generated data source or program is typically converted into a standard tessellation language (STL) file format, although other file formats may also or additionally be used. Typically, the file is loaded into 3D printing software, which takes the file and any user input and divides it into hundreds, thousands, or even millions of "slices." The 3D printing software typically outputs machine instructions, which may be in the form of G-code, that are read by the 3D printer to create each slice of the precursor of the silicone elastomer article. The machine instructions are transferred to the 3D printer, which builds the object (the precursor of the silicone elastomer article) layer by layer based on this slice information in the form of machine instructions. The thickness of these slices may vary.

[0035] Typically, a 3D printer utilizes a dispenser, such as a nozzle or print head, for printing the crosslinkable silicone composition X. Optionally, the dispenser can be heated before, during, and after dispensing the crosslinkable silicone composition X. Two or more dispensers can be utilized, with each dispenser having independently selected properties.

[0036] An extrusion 3D printer is a 3D printer in which material is extruded through a nozzle, syringe, or orifice during the additive manufacturing process. A 3D printer can have one or more nozzles, syringes, or orifices.

[0037] Material extrusion generally works by forcing material through a nozzle, syringe, or orifice to print one cross section of an object. This may be repeated for each subsequent layer. The extruded material bonds to the layer below it during the material's hardening.

[0038] Advantageously, the crosslinkable silicone composition X is extruded through a nozzle, which may be heated to facilitate the dispensing of the crosslinkable silicone composition X.

[0039] The average diameter of the nozzle defines the layer thickness, in one embodiment the nozzle diameter is between 50 and 2,000 μm, preferably between 100 and 1,000 μm, most preferably between 100 and 500 μm.

[0040] The distance between the nozzle and the substrate is an important parameter to ensure good geometry: preferably it is between 50 and 200% of the nozzle average diameter, more preferably between 80 and 120%.

[0041] The crosslinkable silicone composition X dispensed through the nozzle may be provided from a cartridge-like system. The cartridge may include a nozzle or multiple nozzles with an associated fluid reservoir or multiple fluid reservoirs. A coaxial two-cartridge system with a static mixer and only one nozzle may also be used. This is particularly useful when the crosslinkable silicone composition X is a multi-part composition.

[0042] The pressure is adapted to the fluid being dispensed, the average diameter of the associated nozzle, and the printing speed.

[0043] Due to the high shear rates generated during nozzle extrusion, the viscosity of crosslinkable silicone composition X is significantly reduced, thereby enabling printing of fine layers.

[0044] The cartridge pressure may vary from 1 to 28 bar, preferably from 2 to 25 bar, most preferably from 4 to 8 bar. When using nozzle diameters less than 100 μm, the cartridge pressure will be higher than 20 bar to obtain good material extrusion. To withstand such pressures, adapted equipment using aluminum cartridges will be used.

[0045] The nozzle and / or build platform move in the XY (horizontal) plane to complete the cross-section of the object, and then move in the Z (vertical) plane once a layer is completed. The XYZ movement precision of the nozzle is high, around 10 μm. After each layer is printed on the X and Y work planes, the nozzle is moved in the Z direction a sufficient distance to allow the next layer to be applied on the X and Y work planes. In this way, the object that will become the precursor to the silicone elastomer article can be built up one layer at a time, from the bottom up.

[0046] As previously disclosed, the distance between the nozzle and the previous layer is an important parameter to ensure good geometry: it is preferably between 70 and 200%, preferably between 80 and 120% of the nozzle average diameter.

[0047] Advantageously, the printing speed is between 1 and 100 mm / s, preferably between 3 and 50 mm / s, in order to obtain the best compromise between good precision and production speed.

[0048] "Material jetting" is defined as "an additive manufacturing process in which droplets of a build material are selectively deposited". The material is applied (jetted) discontinuously in the form of individual droplets using a printing head to the desired locations of a working surface. 3D devices and methods for the step-by-step manufacture of 3D structures with a printing head array are equipped with at least one, preferably 2 to 200, printing head nozzles, allowing for a suitable site-selective application of multiple materials. The application of materials by inkjet printing imposes certain requirements on the viscosity of the materials.

[0049] In a 3D injection printer, one or more reservoirs are under pressure and connected to a metering nozzle via a metering line. Upstream or downstream of the reservoirs, there may be devices that allow the multi-component silicone composition to mix homogeneously and / or to expel dissolved gases. There may be one or more injection devices that operate independently of each other to build precursors of silicone elastomer articles from different silicone compositions, or in the case of more complex structures, to allow composite parts to be produced from silicone elastomers and other plastics.

[0050] Due to the high shear rates that occur in the metering valve during the injection metering procedure, the viscosity of such silicone compositions is significantly reduced, thus allowing the injection metering of very fine droplets. After the droplets are deposited on the substrate, the viscosity increases again due to a rapid decrease in the shear rate. Thus, the deposited droplets quickly become highly viscous again, allowing the construction of precise shapes of three-dimensional structures.

[0051] Individual metering nozzles can be precisely positioned in the x, y, and z directions to precisely target and deposit droplets of the crosslinkable silicone composition onto a substrate or onto a precursor of a silicone elastomer article that has already been placed thereon in the course of subsequently forming a molded article.

[0052] In a preferred embodiment of the method, the method for additive manufacturing of three-dimensional silicone elastomeric articles uses an extrusion 3D printer.

[0053] In one embodiment of this method, the method for additive manufacturing of three-dimensional silicone elastomeric articles uses an extrusion 3D printer comprising at least nozzles for printing crosslinkable silicone composition X, each nozzle having a diameter of 50-2,000 μm, preferably 100-800 μm, most preferably 100-500 μm.

[0054] The crosslinking step 4) can be carried out at room temperature or by heating. Advantageously, the crosslinking step 4) is carried out at room temperature or by heating at a temperature between 50 and 200°C, preferably between 60 and 100°C, preferably for a period of 10 minutes to 24 hours.

[0055] This crosslinking step can be carried out several times. In one embodiment, step 4) is a step of heating the crosslinkable silicone composition X. Heating can be used to accelerate curing. In another embodiment, step 4) is a step of irradiating the crosslinkable silicone composition X, and irradiation can be with UV light or infrared (IR). Further irradiation can be used to accelerate curing. In another embodiment, step 4) includes both heating and irradiating the crosslinkable silicone composition X.

[0056] It is well known that support materials can be used for additive manufacturing of silicone elastomers, as disclosed, for example, in US Patent Application Publication No. 2015 / 0028523.

[0057] Post-processing options Optional post-treatment steps can greatly improve the surface quality of the printed article. Sanding is a common method to reduce or remove visibly distinct layers of a model. The surface of a silicone elastomer article can be sprayed or coated with a thermal or UV curable RTV or LSR crosslinkable silicone composition to obtain a suitable smooth surface appearance.

[0058] Surface treatment using a laser is also possible.

[0059] For medical applications, sterilization of the final elastomeric article can be obtained, for example, by heating in an autoclave in a dry atmosphere or with steam, by heating the object at temperatures above 100° C., for example under gamma radiation, ethylene oxide sterilization, electron beam sterilization.

[0060] The resulting silicone elastomer article can be any article with a simple or complex shape, for example anatomical models (functional or non-functional) such as hearts, limbs, kidneys, prostates, surgical and educational models, orthotics, prostheses, and various classes of implants such as long-term implants such as hearing aids, stents, laryngeal implants, etc.

[0061] The resulting silicone elastomer article can also be an actuator for robotics, a gasket, a mechanical part for automotive / aerospace, a part for an electronic device, a package for encapsulating components, a vibration isolator, a shock isolator or a noise isolator.

[0062] Crosslinkable silicone composition X The crosslinkable silicone composition X precursor of the silicone elastomer is a crosslinkable silicone composition by polyaddition reaction.

[0063] The crosslinkable silicone composition X is - (A) at least one organopolysiloxane compound A containing per molecule at least two C2-C6 alkenyl radicals bonded to silicon atoms; - (B) at least one organohydrogenopolysiloxane compound B containing per molecule at least two hydrogen atoms bonded to identical or different silicon atoms; - (C) at least one catalyst C comprising at least one metal or compound from the platinum group; - (D) at least one thixotropic agent D selected from organosilicon compounds containing at least one cyclic amine functional group per molecule; (E) at least one filler E; and (F) optionally, at least one crosslinking inhibitor F Includes.

[0064] The crosslinkable silicone composition X is a crosslinkable silicone composition having a viscosity of preferably 1,300 to 10,000 Pa·s, and more preferably 2,000 to 6,000 Pa·s. The viscosity of the silicone composition X is measured at 25°C using a 2° cone plate and a 0.5 s -1 This corresponds to the viscosity measured using a rheometer at a rotational shear rate of 100 rpm.

[0065] The crosslinkable silicone composition X has a nitrogen content of 0.003-0.02% by weight, preferably 0.004-0.017% by weight, more preferably 0.0045-0.016% by weight. The nitrogen content is expressed as the weight percent of the nitrogen element in the crosslinkable silicone composition X. The nitrogen content of the crosslinkable silicone composition X can also be expressed in ppm. In this case, the silicone composition X has a nitrogen content between 30 ppm and 200 ppm, preferably between 40 ppm and 170 ppm, more preferably between 45 ppm and 160 ppm. In a particular embodiment, the nitrogen content is based only on the nitrogen element of the thixotropic agent D containing a cyclic amine functional group.

[0066] In a particular embodiment, the crosslinkable silicone composition X has a yield stress of 400 to 3,000 Pa, preferably 450 to 2,500 Pa, more preferably 500 to 2,250 Pa. The yield stress is the stress at which the crosslinkable silicone composition X starts to flow. The yield stress can be determined using the Herschel-Bulkley model. The yield stress of the crosslinkable silicone composition X is determined by rotational shear measurements at 25°C using a rheometer with a 20 mm cone-plate geometry and a 2° cone angle. The rotational shear measurements are performed as follows: 0 to 20 s -1 Up to 120s, 20 to 0s -1 The measured stress is then plotted as a function of the applied shear stress. -1 Using the linear portion of the curve up to the yield stress (approximately 20 to 2.5s -1 A linear regression is performed on this linear portion of the curve to determine the yield stress corresponding to the intercept.

[0067] Crosslinkable silicone composition X can be used to print silicone elastomer articles. Due to the specific nitrogen content, the composition can have suitable rheological properties and good reactivity. In particular, crosslinkable silicone composition X has good printability and can be put into a cartridge. Furthermore, little loss of reactivity is observed in this composition. The silicone elastomer articles obtained by this method also have good mechanical properties.

[0068] Organic Polysiloxane A According to a particularly advantageous embodiment, organopolysiloxane A contains per molecule at least two C2-C6 alkenyl radicals bonded to silicon atoms, (i) at least two of the following formulas: [ka] Siloxyl units (A.1), which may be the same or different, have the formula: where: - a=1 or 2, b=0, 1 or 2, and a+b=1, 2 or 3; - each symbol W may be the same or different and represents a linear or branched C2-C6 alkenyl group; each symbol Z, which may be identical or different, represents a monovalent hydrocarbon-based radical containing 1 to 30 carbon atoms, which is preferably selected from the group formed by alkyl radicals containing 1 to 8 carbon atoms and aryl radicals containing 6 to 12 carbon atoms, and further preferably selected from the group formed by the methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl radicals, (ii) and optionally a compound of the formula [ka] At least one siloxyl unit having: where: - a=0, 1, 2, or 3, - Each symbol Z1 represent, which may be identical or different, a monovalent hydrocarbon-based radical containing 1 to 30 carbon atoms, which is preferably selected from the group formed by alkyl radicals containing 1 to 8 carbon atoms and aryl radicals containing 6 to 12 carbon atoms, and even more preferably selected from the group formed by the methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl radicals.

[0069] Advantageously, Z and Z 1 is selected from the group formed by the methyl and phenyl radicals, and W is selected from the list: vinyl, propenyl, 3-butenyl, 5-hexenyl, 9-decenyl, 10-undecenyl, 5,9-decadienyl and 6-11-dodecadienyl, preferably W is vinyl.

[0070] In a preferred embodiment, in formula (A.1), a=1 and a+b=2 or 3, and in formula (A.2), a=2 or 3.

[0071] These organic polysiloxanes A may have a linear, branched or cyclic structure, and their polymerization degree is preferably 2 to 5,000.

[0072] When they are linear polymers, they are essentially formed from siloxyl units D and M, the siloxyl units D being the siloxyl units WSiO 2 / 2 , WZSiO 2 / 2 and Z 1 2SiO 2 / 2 and the siloxyl unit M is selected from the group formed by the siloxyl unit WSiO 1 / 2 , WZ2SiO 1 / 2 , W2ZSiO 1 / 2 and Z 1 3SiO 1 / 2 The symbols W, Z and Z 1 is as stated above.

[0073] Examples of terminal units M include trimethylsiloxy, dimethylphenylsiloxy, dimethylvinylsiloxy and dimethylhexenylsiloxy groups.

[0074] Examples of units D include dimethylsiloxy, methylphenylsiloxy, methylvinylsiloxy, methylbutenylsiloxy, methylhexenylsiloxy, methyldecenylsiloxy and methyldecadienylsiloxy groups.

[0075] The organopolysiloxane A can be an oil or a gum having a dynamic viscosity of about 10 to 10,000,000 mPa·s at 25°C, typically about 1,000 to 120,000 mPa·s at 25°C.

[0076] When they are cyclic organopolysiloxanes, they may be of the dialkylsiloxy, alkylarylsiloxy, alkylvinylsiloxy or alkylsiloxy type, having the following formula: WSiO 2 / 2 , Z2SiO 2 / 2 or WZSiO 2 / 2 Examples of such siloxyl units have already been mentioned above. The cyclic organopolysiloxane A has a viscosity of about 10 to 5,000 mPa·s at 25° C.

[0077] Preferably, the organopolysiloxane compound A has a mass content of Si-vinyl units of 0.001 to 30%, preferably 0.01 to 10%.

[0078] Organic Hydrogenopolysiloxane B The organohydrogenopolysiloxane compound B is an organopolysiloxane containing per molecule at least two hydrogen atoms bonded to the same or different silicon atoms, and preferably containing per molecule at least three hydrogen atoms bonded directly to the same or different silicon atoms.

[0079] Advantageously, the organohydrogenopolysiloxane compound B is an organopolysiloxane comprising: (i) the following formula: [ka] At least two siloxyl units, preferably at least three siloxyl units, having: where: - d=1 or 2, e=0, 1 or 2, and d+e=1, 2 or 3, - Each symbol Z 3 are identical or different and represent a monovalent hydrocarbon-based radical containing 1 to 30 carbon atoms, which is preferably selected from the group formed by alkyl radicals containing 1 to 8 carbon atoms and aryl radicals containing 6 to 12 carbon atoms, more preferably selected from the group formed by the methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl radicals, (ii) optionally, a compound of the formula: [ka] At least one siloxyl unit having: where: - c=0, 1, 2, or 3, - Each symbol Z 2 are the same or different and represent a monovalent hydrocarbon group containing 1 to 30 carbon atoms, which is preferably selected from the group formed by alkyl groups containing 1 to 8 carbon atoms and aryl groups containing 6 to 12 carbon atoms, more preferably selected from the group formed by methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl radicals.

[0080] The organohydrogenopolysiloxane compound B may be formed exclusively from siloxyl units of formula (B.1) or may also contain units of formula (B.2). It may have a linear, branched or cyclic structure. The degree of polymerization is preferably greater than or equal to 2. More generally, it is less than 5,000.

[0081] Examples of siloxyl units of formula (B.1) are in particular the following units: H(CH3)2SiO 1 / 2 , H(CH3)SiO 2 / 2 and H(CH)SiO 2 / 2 .

[0082] When they are linear polymers, they are essentially formed from: - The following formula Z 2 2SiO 2 / 2 or Z 3 HSiO 2 / 2 and a siloxyl unit D selected from units having the formula: - The following formula Z 2 3SiO 1 / 2 or Z 3 2HSiO 1 / 2 A siloxyl unit M selected from units having the formula: Symbol Z 2 and Z 3 is as described above.

[0083] These linear organopolysiloxanes can be oils having a dynamic viscosity of about 1 to 100,000 mPa·s at 25° C., typically about 10 to 5,000 mPa·s at 25° C., or gums having a dynamic viscosity of about 1,000,000 mPa·s or greater at 25° C.

[0084] When they are cyclic organopolysiloxanes, they are represented by the following formula Z 2 2SiO 2 / 2 and Z 3 HSiO 2 / 2 These are formed from siloxyl units D having the dialkylsiloxy or alkylarylsiloxy type or units Z 3 HSiO 2 / 2 It is formed only from the symbol Z2 and Z 3 are as above. Their viscosities are about 1 to 5,000 mPa·s.

[0085] Examples of linear organohydrogenopolysiloxane compounds B are dimethylpolysiloxanes having hydrogenodimethylsilyl end groups, dimethylpolysiloxanes having trimethylsilyl end groups, hydrogenomethylpolysiloxanes, dimethylpolysiloxanes having hydrogenodimethylsilyl end groups, hydrogenomethylpolysiloxanes, hydrogenomethylpolysiloxanes having trimethylsilyl end groups, and cyclic hydrogenomethylpolysiloxanes.

[0086] General formula (B.3) [ka] Particularly preferred as organohydrogenopolysiloxane compounds B are oligomers and polymers corresponding to: where: - x and y are integers ranging from 0 to 200, - Each symbol R 1 may be the same or different and independently represent: linear or branched alkyl radicals containing from 1 to 8 carbon atoms and optionally substituted with at least one halogen, preferably fluorine, and preferably methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl; Cycloalkyl radicals containing 5 to 8 cyclic carbon atoms, Aryl radicals containing 6 to 12 carbon atoms, or · Aralkyl radicals having an alkyl portion containing 5 to 14 carbon atoms and an aryl portion containing 6 to 12 carbon atoms.

[0087] The following compounds [ka] are particularly suitable according to the invention as organohydrogenopolysiloxane compounds B: a, b, c, d, and e are defined below. - a polymer of formula S1: - 0≦a≦150, preferably 0≦a≦100, more particularly 0≦a≦20, and 1≦b≦90, preferably 10≦b≦80, more particularly 30≦b≦70, in the polymer of formula S2: 0≦c≦100, preferably 0≦c≦15 in the polymer of formula S3: 5≦d≦200, preferably 20≦d≦100, and 2≦e≦90, preferably 10≦e≦70.

[0088] In particular, organohydrogenopolysiloxane compounds B suitable for use in the present invention are compounds of formula S1, where a=0.

[0089] Preferably, organohydrogenopolysiloxane compound B has a mass content of SiH units of 0.2 to 91%, preferably 0.2 to 50%.

[0090] In one embodiment, the organohydrogenopolysiloxane compound B is a branched polymer. The branched organohydrogenopolysiloxane compound B is a) Formula R3SiO 1 / 2 Siloxyl unit M of formula RSiO 2 / 2 Siloxyl units D of the formula RSiO 3 / 2 of siloxyl units T and of formula SiO 4 / 2 wherein R is a siloxyl unit that is a monovalent hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom; and b) with the proviso that at least one of these siloxyl units is a siloxyl unit T or Q, and at least one of the siloxyl units M, D or T contains a Si-H group; Includes.

[0091] Thus, according to one preferred embodiment, the branched organohydrogenopolysiloxane compound B can be selected from the following group: an organopolysiloxane resin of formula M'Q formed essentially from (a) Formula R2HSiO 1 / 2 and a monovalent siloxy unit M'; (b) Formula SiO 4 / 2 a tetravalent siloxy unit Q; and - an organopolysiloxane resin of formula MD'Q consisting essentially of the following units: (a) Formula RHSiO 2 / 2 a divalent siloxy unit D'; (b) Formula R3SiO 1 / 2 a monovalent siloxy unit M of the formula: (c) Formula SiO 4 / 2 a tetravalent siloxy unit Q; Here, R represents a monovalent hydrocarbyl having 1 to 20 carbon atoms, preferably a monovalent aliphatic or aromatic hydrocarbyl having 1 to 12, more preferably 1 to 8 carbon atoms.

[0092] In a further embodiment, a mixture can be used of at least a linear organohydrogenopolysiloxane compound B and at least a branched organohydrogenopolysiloxane compound B. In this case, the linear and branched organohydrogenopolysiloxane compounds B can be mixed in any ratio within a wide range, which can be adjusted depending on the desired product properties, such as hardness and the ratio of Si-H to alkenyl groups.

[0093] In the present invention, the ratio of organopolysiloxane A to organohydrogenopolysiloxane B is such that the molar ratio of silicon-bonded hydrogen atoms (Si-H) in organohydrogenopolysiloxane B to silicon-bonded alkenyl radicals (Si-CH=CH2) in organopolysiloxane A can be between 0.2 and 20, preferably between 0.5 and 15, more preferentially between 0.5 and 10, and even more preferentially between 0.5 and 5.

[0094] Catalyst C Catalysts C containing at least one metal or compound from the platinum group are well known. The platinum group metals are, in addition to platinum, ruthenium, rhodium, palladium, osmium and iridium in combination, known as platinoids. Platinum and rhodium compounds are preferably used. Complexes of platinum with organic products, as described in US Pat. No. 3,159,601, US Pat. No. 3,159,602, US Pat. No. 3,220,972 and EP-A-0,057,459, EP-A-0,188,978 and EP-A-0,190,530, and complexes of platinum with vinylorganosiloxanes, as described in US Pat. No. 3,419,593, US Pat. No. 3,715,334, US Pat. No. 3,377,432 and US Pat. No. 3,814,730, can be used in particular. Specific examples include platinum metal powder, chloroplatinic acid, complexes of chloroplatinic acid and β-diketones, complexes of chloroplatinic acid and olefins, complexes of chloroplatinic acid and 1,3-divinyltetramethyldisiloxane, complexes of silicone resin powders containing the above catalysts, rhodium compounds such as those represented by the formulas RhCl(Ph3P)3, RhCl3[S(C4H9)2]3, etc.; tetrakis(triphenyl)palladium, and mixtures of palladium black and triphenylphosphine.

[0095] The platinum catalyst should preferably be used in a catalytically sufficient amount to allow sufficiently rapid crosslinking at room temperature, typically from 1 to 200 ppm by weight, preferably from 1 to 100 ppm by weight, more preferably from 1 to 50 ppm by weight, of catalyst based on the amount of Pt metal relative to the total silicone composition.

[0096] Thixotropic agent D Crosslinkable silicone composition X also includes thixotropic agent D, which is a rheological agent that serves to tailor shear thinning and thixotropic properties. In particular, thixotropic agent D allows crosslinkable silicone composition X to have a tunable viscosity in response to an applied stress. When stress is applied to the composition, the viscosity decreases to enable printing, and when the stress is removed, the viscosity returns to its original value.

[0097] The thixotropic agent D is selected from organosilicon compounds containing at least one cyclic amine functional group per molecule. The cyclic amine functional group of the thixotropic agent D can be a piperidinyl functional group.

[0098] In certain embodiments, the thixotropic agent D has, per mole, at least one compound represented by the general formula: (R) a (X) b ZSiO (3-(a+b)) / 2 (D1) is an organopolysiloxane having the formula where: - each R symbol is the same or different and represents a monovalent hydrocarbon radical selected from the group consisting of linear or branched alkyl radicals having 1 to 6 carbon atoms, the phenyl radical and the 3,3,3-trifluoropropyl radical; - each X symbol is the same or different and represents a monovalent radical selected from the group consisting of a hydroxyl group, an alkenyl radical having 2 to 6 carbon atoms, and an alkoxy radical having 1 to 6 carbon atoms; Z is a group of formula (I) [ka] represents a group having a sterically hindered piperidinyl group of: where: - R 1is a linear or branched alkylene radical having 2 to 18 carbon atoms; an alkylenecarbonyl radical having a linear or branched alkylene moiety of 2 to 20 carbon atoms; an alkylenecyclohexylene radical having a linear or branched alkylene moiety of 2 to 12 carbon atoms and a -OH group and, optionally, one or two alkyl radicals having 1 to 4 carbon atoms in the cyclohexylene moiety; 4 -OR 5 - radical, R 4 and R 5 The radicals are the same or different and represent alkylene radicals having 1 to 12 carbon atoms; 4 -OR 5 - radical, R 4 and R 5 Radicals have the above meanings, one or both of which are substituted by one or two OH groups; 4 -COO-R 5 -and-R 4 -OCO-R 5 - radical, R 4 and R 5 is a radical having the above meaning; or a group of the formula -R 6 -OR 7 -O-CO-R 8 - radical, R 6 , R 7 and R 8 are the same or different and represent alkylene radicals having 2 to 12 carbon atoms; R 7 The radical is an optionally hydroxyl substituted radical; - U may be present or absent, and if present, U is -O- or -NR 9 - represents R 9 is a hydrogen atom; a linear or branched alkyl radical having 1 to 6 carbon atoms; a divalent radical -R as defined above 1 -, where one valence bond is -NR 9 a radical having one end connected to a nitrogen atom of - and the other to a silicon atom; or a divalent radical of formula (II): [ka] Here, R 1 has the above meaning, R 2 and R 3 has the following meaning, R 10 represents a linear or branched alkylene radical having 1 to 12 carbon atoms and one of the valence bonds (R 10 The bond is -NR 9 - is bonded to the nitrogen atom of the other (R 1 bond) is bonded to a silicon atom; Each R 2 are the same or different and are derived from a linear or branched alkyl radical having 1 to 3 carbon atoms or a phenyl radical; R 3 is a hydrogen atom or R 2 Represents radical; - a is a number selected from 0, 1, and 2; - b is a number selected from 0, 1, and 2; and - a+b is at most 2.

[0099] Preferably, in the group of formula (I): - R 1 is a linear or branched alkylene group having 2 to 18 carbon atoms, preferably 2 to 6 carbon atoms; - U stands for -O-; - Each R 2 are the same or different and consist of linear or branched alkyl groups having 1 to 3 carbon atoms; - R 3 represents a hydrogen atom.

[0100] The thixotropic agent D has the formula: (R) e (X) f SiO (4-(e+f)) / 2 (D2) Further comprising other siloxyl units of the formula: where: - R, X have the same meanings as given for formula (D1); - e is a number selected from 0, 1, 2, and 3; - f is a number selected from 0, 1, 2, and 3; and - e+f is at most 3.

[0101] In certain embodiments, the thixotropic agent D has the formula: (R) e (X 1 ) f SiO (4-(e+f)) / 2 (D3) Further comprising other siloxyl units of the formula: where: R has the same meaning as given for formula (D1); - each X 1 The symbols may be the same or different and represent alkenyl radicals having 2 to 6 carbon atoms; - e is a number selected from 0, 1, and 2; - f is a number selected from 1, 2, and 3; and - e+f is at most 3.

[0102] In certain embodiments, the thixotropic agent D has the general formula: [ka] is a linear organopolysiloxane of the formula where: - the R and Z symbols have the meaning given above for formula (D1); - the Y symbol represents a monovalent radical selected from the R, Z and X radicals defined above for formula (D1); - Each R 14 the symbols are the same or different and represent monovalent radicals selected from the R and X radicals defined above for formula (D1); and x and y represent integers or fractions equal to or greater than zero, with the proviso that if x=0 then at least one of the two Y radicals represents a Z radical.

[0103] In certain embodiments, the thixotropic agent D has the general formula: [ka] is a cyclic organopolysiloxane of the formula where: - the R and Z symbols have the meaning given above for formula (D1); x' is an integer greater than or equal to 1, and y' is an integer greater than or equal to 0, with the proviso that x'+y'>=3.

[0104] The thixotropic agent D may correspond to the formula: [ka] where: - x'' is between 0 and 2,000, preferably between 0 and 1,500; y'' is between 1 and 50, preferably between 1 and 20.

[0105] In certain embodiments, the thixotropic agent D has the general formula: [ka] is a linear organopolysiloxane of the formula where: the R and Z symbols have the meanings given above for formula (D1), - each X 1 The symbols have the meanings given above for formula (D3), m is between 0 and 2,000, preferably between 1 and 1,700, more preferably between 75 and 1,600, n is between 1 and 50, preferably between 1 and 25, more preferably between 2 and 20.

[0106] Advantageously, the thixotropic agent D has the formula (D7'): [ka] and where - m is between 0 and 2,000, preferably between 1 and 1,700, more preferably between 75 and 1,600, even more preferably m is 100; n is between 1 and 50, preferably between 1 and 25, more preferably between 2 and 20, even more preferably n is 2.

[0107] In one embodiment, the organopolysiloxane has formula (D7') where m is 100 and n is 2.

[0108] In another particular embodiment, the thixotropic agent D corresponds to the formula: [ka] where n is between 1 and 10.

[0109] According to another embodiment, the thixotropic agent D corresponds to the following formula: [ka] where n' is between 3 and 10.

[0110] The amount of thixotropic agent D is between 0.05 and 3% by weight, preferably between 0.1 and 2.5% by weight, of the total weight of crosslinkable silicone composition X, provided that the nitrogen content in the composition is respected.

[0111] The crosslinkable silicone composition X has a nitrogen content of 0.003-0.02% by weight, preferably 0.004-0.017% by weight, more preferably 0.0045-0.016% by weight. In a particular embodiment, the nitrogen content is based only on the nitrogen element of the thixotropic agent D containing a cyclic amine functional group. The particular nitrogen content allows the composition to have suitable rheological properties and good reactivity. In particular, the crosslinkable silicone composition X has good printability and can be placed in a cartridge. Furthermore, little loss of reactivity is observed in this composition. For example, after one month of storage, the crosslinking rate may correspond to at least 80% of the nominal value measured initially at the same temperature. Furthermore, the silicone elastomer article obtained by this method also has good mechanical properties.

[0112] If the cross-linkable silicone composition X has too high a nitrogen content, i.e., greater than 0.02 wt %, the reactivity of the composition decreases and the cross-linking rate is too low, so that the composition cannot be used for 3D printing.

[0113] Conversely, if the nitrogen content of crosslinkable silicone composition X is too low, i.e., less than 0.003 wt %, the composition will not have suitable rheological properties and cannot be used for 3D printing.

[0114] Filler E To allow a sufficiently high mechanical strength, the crosslinkable silicone composition X contains a filler such as, for example, fine silica particles as reinforcing filler E. It is possible to use precipitated silica, fumed silica and mixtures thereof. These active reinforcing fillers have a specific surface area of ​​at least 50 m, measured by the BET method. 2 / g, preferably 100 to 400m 2 / g. This kind of active reinforcing filler is a very well-known material in the field of silicone rubber. The silica filler may be hydrophilic or may be hydrophobized by known processes.

[0115] In a preferred embodiment, the silica reinforcing filler has a viscosity of at least 50 mm as measured by the BET method. 2 / g, preferably 100 to 400m 2 The fumed silica has a specific surface area in the range of 1 / g. The fumed silica may be used as is, but is preferably subjected to a hydrophobic surface treatment. In this case, when using fumed silica that has been subjected to a hydrophobic surface treatment, the fumed silica may be used that has been subjected to a hydrophobic surface treatment in advance, or the fumed silica may be treated in situ by adding a surface treatment agent when mixing the fumed silica with the organic polysiloxane A.

[0116] The surface treatment agent may be selected from conventionally used treatment agents such as alkylalkoxysilanes, alkylchlorosilanes, alkylsilazanes, silane coupling agents, titanate-based treatment agents, and fatty acid esters. The treatment agent may be used alone or in combination of two or more treatment agents at the same time or at different times.

[0117] The amount of silica reinforcing filler E in the addition crosslinking silicone composition is in the range of 5 to 40% by weight, and preferably 10 to 35% by weight, of the total weight of the crosslinkable silicone composition X. If the blending amount is less than 5% by weight, sufficient elastomer strength may not be obtained, whereas if it exceeds 40% by weight, practical blending may become difficult.

[0118] Silicone compositions according to the present invention may also contain other fillers such as standard semi-reinforcing or packing fillers, hydroxyl-functional silicone resins, pigments, or adhesion promoters.

[0119] Non-siliceous minerals included as semi-reinforcing or packing mineral fillers can be selected from the group consisting of carbon black, titanium dioxide, aluminum oxide, alumina hydrate, calcium carbonate, ground quartz, diatomaceous earth, zinc oxide, mica, talc, iron oxide, barium sulfate, and hydrated lime.

[0120] Silicone resin is Q:SiO 2 / 2 and T: RSiO 3 / 2 Hydroxyl-functional silicone resins are well known and can be selected from MQ(OH), MDT(OH), or DT(OH) resins, where M:R1R2R3SiO 1 / 2 , D: R1R2SiO 2 / 2 , Q(OH):(OH)SiO 3 / 2 , and T(OH):(OH)RSiO 2 / 2 and the R1, R2, and R3 groups are independently selected from the following: - a linear or branched alkyl group containing 1 to 8 carbon atoms, optionally substituted with one or more halogen atoms; and - an aryl or alkylaryl group containing 6 to 14 carbon atoms. Preferably, the hydroxyl functional silicone resin is an MQ(OH) resin.

[0121] Crosslinking inhibitor F The crosslinkable silicone composition X may comprise a crosslinking inhibitor F. In a particular embodiment, the crosslinkable silicone composition X does not comprise a crosslinking inhibitor F. In another particular embodiment, the crosslinkable silicone composition X comprises a crosslinking inhibitor F. Crosslinking inhibitors are generally used in addition to crosslinking the silicone composition to retard the curing of the composition at ambient temperature. The crosslinking inhibitor F may be chosen from the following compounds: - Acetylenic Alcohol - organopolysiloxanes substituted with at least one alkenyl, which may optionally be in cyclic form, tetramethylvinyltetrasiloxane being particularly preferred; - pyridine, - organic phosphines and phosphites, unsaturated amides, and - Alkyl and aryl maleates

[0122] These acetylenic alcohols (see cf. FR-B-1528464 and FR-A-2372874) are among the preferred hydrosilylation reaction thermal blockers and have the formula: (R')(R")(OH)CC≡CH where: - R' is a linear or branched alkyl radical, or a phenyl radical; and - R" is H or a linear or branched alkyl radical, or a phenyl radical; the radicals R' and R" and the carbon atom α to the triple bond can form a ring.

[0123] The total number of carbon atoms contained in R' and R'' is at least 5, preferably 9 to 20. Of said acetylenic alcohols, examples that may be mentioned include: - 1-ethynyl-1-cyclohexanol; - 3-methyl-1-dodecyn-3-ol; - 3,7,11-trimethyl-1-dodecyn-3-ol; - 1,1-diphenyl-2-propyn-1-ol; - 3-ethyl-6-ethyl-1-nonyn-3-ol; - 2-Methyl-3-butyn-2-ol; - 3-methyl-1-pentadecin-3-ol; and - diallyl maleate or diallyl maleate derivatives.

[0124] In a preferred embodiment, the crosslinking inhibitor is 1-ethynyl-1-cyclohexanol.

[0125] To obtain a longer working time or "pot life", the amount of inhibitor is adjusted to reach the desired "pot life". The concentration of catalyst inhibitor in the silicone composition is sufficient to retard the cure of the composition at ambient temperature. This concentration will vary widely depending on the particular inhibitor used, the nature and concentration of the hydrosilylation catalyst, and the nature of the organohydrogenopolysiloxane. In some cases, inhibitor concentrations of 1 mole per mole of platinum group metal will provide sufficient storage stability and cure speed. In other instances, inhibitor concentrations of up to 500 moles or more per mole of platinum group metal may be required. The optimum concentration of inhibitor in a given silicone composition can be readily determined by routine experimentation.

[0126] Advantageously, the amount of crosslinking inhibitor F in the addition-crosslinking silicone composition ranges from 0.01% to 0.2% by weight, preferably from 0.03% to 0.15% by weight, relative to the total weight of the crosslinkable silicone composition X.

[0127] The use of an inhibitor is effective in avoiding premature curing of the silicone composition at the tip of the nozzle and subsequent deterioration of the printed layer.

[0128] In a preferred embodiment, the crosslinkable silicone composition X of the present invention contains, per 100% by weight of the silicone composition: - 45 to 80% by weight of at least one organopolysiloxane compound A, - 0.1 to 10% by weight of at least one organohydrogenopolysiloxane compound B, - 0.05 to 3% by weight of at least one thixotropic agent D, - 5 to 40% by weight of at least one filler E, - 0.001 to 0.01% by weight of platinum, and - optionally, 0.01 to 0.2% by weight of at least one crosslinking inhibitor F Includes.

[0129] According to one embodiment, the crosslinkable silicone composition X is - (A) at least one organopolysiloxane compound A containing per molecule at least two C2-C6 alkenyl radicals bonded to silicon atoms; - (B) at least one organohydrogenopolysiloxane compound B containing per molecule at least two hydrogen atoms bonded to identical or different silicon atoms; - (C) at least one catalyst C comprising at least one metal or compound from the platinum group; - (D) per mole of the general formula: (R) a (X) b ZSiO (3-(a+b)) / 2 (D1) at least one thixotropic agent D chosen from organopolysiloxanes having at least one unit represented by where: - each R symbol is the same or different and represents a monovalent hydrocarbon radical selected from the group consisting of linear or branched alkyl radicals having 1 to 6 carbon atoms, the phenyl radical, and the 3,3,3-trifluoropropyl radical; - each X symbol is the same or different and represents a monovalent radical selected from the group consisting of a hydroxyl group, an alkenyl radical having 1 to 3 carbon atoms and an alkoxy radical; Z represents a radical carrying a sterically hindered piperidinyl group selected from the group consisting of radicals of formula (I): [ka] where: - R 1 is a linear or branched alkylene radical having 2 to 18 carbon atoms; an alkylenecarbonyl radical having a linear or branched alkylene moiety of 2 to 20 carbon atoms; an alkylenecyclohexylene radical having a linear or branched alkylene moiety of 2 to 12 carbon atoms and an alkylenecyclohexylene radical having an -OH group and, optionally, one or two alkyl radicals having 1 to 4 carbon atoms in the cyclohexylene moiety; 4 -OR 5-, where R 4 and R 5 The radicals are the same or different and represent alkylene radicals having 1 to 12 carbon atoms; 4 -OR 5 -, where R 4 and R 5 Radicals have the above meanings, one or both of which are substituted by one or two OH groups; radicals of the formula -R 4 -COO-R 5 -and-R 4 -OCO-R 5 -, where R 4 and R 5 is a radical having the above meaning; or a group of the formula -R 6 -OR 7 -O-CO-R 8 -, where R 6 , R 7 and R 8 are the same or different and represent alkylene radicals having 2 to 12 carbon atoms; R 7 The radical is a radical optionally substituted with a hydroxyl group; - U may be present or absent, and if present, U is -O- or -NR 9 - represents R 9 is a hydrogen atom; a linear or branched alkyl radical having 1 to 6 carbon atoms; - Each R 2 are the same or different and are selected from linear or branched alkyl radicals having 1 to 3 carbon atoms or phenyl radicals; and - R 3 is a hydrogen atom or R 2 Represents radical; - a is a number selected from 0, 1, and 2; - b is a number selected from 0, 1, and 2; and - a+b is at most 2; (E) at least one filler E; and (F) optionally, at least one crosslinking inhibitor F Includes.

[0130] Other Additives The crosslinkable silicone composition X may further comprise functional additives which are customary in silicone compositions. The following functional groups of additives may be cited: - adhesion promoters; - silicone resin; - Rheology modifiers such as thixotropic agents, viscosity modifiers, yield stress agents; - colorants, including phosphorescent agents and chromic pigments, such as photochromic pigments, thermochromic pigments, electrochromic pigments, piezochromic pigments, solvatochromic pigments and cursorochromic pigments; and - Additives for heat, oil and fire resistance, e.g. metal oxides.

[0131] Adhesion promoters are widely used in silicone compositions. Advantageously, in the process according to the invention it is possible to use one or more adhesion promoters selected from the group consisting of: - alkoxylated organosilanes containing at least one C2-C6 alkenyl group per molecule; - an organosilicate compound containing at least an epoxy radical - chelates of metal M and / or metal alkoxides of the formula: M(OJ)n, wherein M is selected from the group consisting of Ti, Zr, Ge, Li, Mn, Fe, Al and Mg or mixtures thereof; n=the valence of M and J=a linear or branched alkyl group of C1 to C8; Preferably, M is selected from the group consisting of Ti, Zr, Ge, Li or Mn, more preferably M is titanium. For example, it is possible to associate alkoxy radicals of the butoxy type.

[0132] Silicone resins are well known and commercially available branched organopolysiloxanes. They have the formula RSiO1 / 2 (M units), R2SiO 2 / 2 (D units), RSiO 3 / 2 (T units) and SiO 4 / 2 (Q units), at least one of which is a T or Q unit.

[0133] Each radical R is the same or different and is selected from the group consisting of C1-C6 linear or branched alkyl, hydroxyl, phenyl, trifluoro-3,3,3propyl. Alkyl radicals are, for example, methyl, ethyl, isopropyl, tertiobutyl and n-hexyl.

[0134] Examples of branched oligomers or organopolysiloxane polymers include MQ, MDQ, TD and MDT resins, where the hydroxyl functionality may be carried by M, D and / or T units. Examples of particularly suitable resins include hydroxylated MDQ resins having 0.2-10% by weight of hydroxyl groups.

[0135] Multipart Composition The crosslinkable silicone composition X may be a one-part composition containing components A to E in a single part, or may be a multi-part composition containing these components in two or more parts, provided that components B and C are not present in the same part. For example, the multi-part composition may include a first part containing a part of component A and all of component C, and a second part containing the remaining part of component A and all of component B. In certain embodiments, component A is in the first part, component B is in a second part separate from the first part, and component C is in the first part, the second part, and / or a third part separate from the first and second parts. Components D, E, and F may be present in the respective part (or parts) together with at least one of components B or C, and / or may be present in separate parts (or parts).

[0136] One-part compositions are typically prepared by combining the major and optional components in the proportions described at ambient temperature. If the composition is to be used immediately, the order of addition of the various components is not critical, although the hydrosilylation catalyst is typically added last, at temperatures below about 30° C., to prevent premature curing of the composition.

[0137] Also, multi-part compositions can be prepared by combining the components of each part. Mixing can be accomplished by any technique understood in the art, such as blending or stirring, either in a batch process or a continuous process in a specific device. The specific device is determined by the viscosity of the components and the viscosity of the final composition.

[0138] In certain embodiments, when crosslinkable silicone composition X is a multi-part silicone composition, the separate parts of the multi-part crosslinkable silicone composition may be mixed in a dispense printing nozzle, such as a dual dispense printing nozzle, before and / or during printing. Alternatively, the separate parts can be combined immediately prior to printing.

[0139] Organopolysiloxane of formula (D7) The present invention also relates to an organopolysiloxane of formula (D7): [ka] where: - each R symbol is the same or different and represents a monovalent hydrocarbon radical selected from the group consisting of linear or branched alkyl radicals having 1 to 6 carbon atoms, the phenyl radical, and the 3,3,3-trifluoropropyl radical; - each X 1 The symbols may be the same or different and represent alkenyl radicals having 2 to 6 carbon atoms; Z represents a group carrying a sterically hindered piperidinyl group of formula (I): [ka] where: - R 1 is a linear or branched alkylene radical having 2 to 18 carbon atoms; an alkylenecarbonyl radical having a linear or branched alkylene moiety of 2 to 20 carbon atoms; an alkylenecyclohexylene radical having a linear or branched alkylene moiety of 2 to 12 carbon atoms and an alkylenecyclohexylene radical having an -OH group and, optionally, one or two alkyl radicals having 1 to 4 carbon atoms in the cyclohexylene moiety; 4 -OR 5 -, where R 4 and R 5 The radicals are the same or different and represent alkylene radicals having 1 to 12 carbon atoms; 4 -OR 5 -, where R 4 and R 5 Radicals have the above meanings, one or both of which are substituted by one or two OH groups; radicals of the formula -R 4 -COO-R 5 -and-R 4 -OCO-R 5 -, where R 4 and R 5 is a radical having the above meaning; or a group of the formula -R 6 -OR 7 -O-CO-R 8 -, where R 6 , R 7 and R 8 are the same or different and represent alkylene radicals having 2 to 12 carbon atoms; R 7 The radical is an optionally hydroxyl substituted radical; - U may be present or absent, and if present, U is -O- or -NR 9 - represents R 9 is a hydrogen atom; a linear or branched alkyl radical having 1 to 6 carbon atoms; a divalent radical -R 1 -wherein R 1has the meaning given above, and one of the valence bonds is -NR 9 a radical having the formula -, and the other bonded to a silicon atom; or [ka] is a divalent radical of: Here, R 1 has the above meaning, R 2 and R 3 has the following meaning, R 10 represents a linear or branched alkylene radical having 1 to 12 carbon atoms, and one of the valence bonds (R 10 The bond is -NR 9 - is bonded to the nitrogen atom of, and the other (R 1 bond) is bonded to a silicon atom; Each R 2 are the same or different and are selected from linear or branched alkyl radicals having 1 to 3 carbon atoms or phenyl radicals; R 3 is a hydrogen atom or R 2 Represents radical; - m is 0 to 2,000, preferably 1 to 1,700, more preferably 75 to 1,600, n is an integer of 1 to 50, preferably 1 to 25, and more preferably 2 to 20.

[0140] Preferably, in the group of formula (I): - R 1 is a linear or branched alkylene radical having 2 to 18 carbon atoms, preferably 2 to 6 carbon atoms; - U stands for -O-; - Each R 2 are the same or different and consist of linear or branched alkyl radicals having 1 to 3 carbon atoms, - R 3 represents a hydrogen atom.

[0141] Advantageously, the organopolysiloxane has formula (D7'): [ka] where - m is between 0 and 2,000, preferably between 1 and 1,700, more preferably between 75 and 1,600, even more preferably m is 100; n is between 1 and 50, preferably between 1 and 25, more preferably between 2 and 20, even more preferably n is 2.

[0142] In one embodiment, the organopolysiloxane is of formula (D7'), where m is 100 and n is 2.

[0143] The present invention also relates to a method for synthesizing a compound of formula (D7), said method comprising the steps of: 1. contacting divinyltetramethyldisiloxane, a cyclic polydimethylsiloxane, and a cyclic polymethylsiloxane containing a functional group Z bonded to a silicon atom; 2. Heating and introducing a basic catalyst, such as a strong base, to react; and 3. Neutralization, for example with an acid, followed by isolation of the organopolysiloxane containing functional groups Z, for example by standard devolatilization; cooling and draining.

[0144] The present invention also relates to a composition comprising an organopolysiloxane of formula (D7).

[0145] Since the organopolysiloxane of formula (D7) has vinyl groups, this compound can be used as a substrate for polyaddition reaction.Therefore, after reaction, the organopolysiloxane of formula (D7) is part of a crosslinked network, and there is no risk of this organopolysiloxane migrating.As a result, the silicone elastomer article obtained after crosslinking has a low concentration of extractable compounds and / or is low in toxicity.

[0146] The following examples are intended to illustrate, but not limit, the invention. EXAMPLES

[0147] raw materials Amounts are expressed in weight percent unless otherwise stated. Nitrogen content may be expressed in ppm.

[0148] Thixotropic agent D Table 1 summarizes the properties of the thixotropic agent D that was tested. [Table 1]

[0149] [ka] [ka] [ka]

[0150] Thixotropic agent D C was prepared as follows: A 500 mL round bottom flask containing a stirring magnet was charged with 9.4 g of divinyltetramethyldisiloxane, 448.0 g of octamethylcyclotetrasiloxane, and 29.8 g of tetramethyltetra(2,2,6,6-tetramethyl-4-(propoxy)piperidine)cyclotetrasiloxane. The mixture was then heated to 160°C and 3.8 g of potassium silanolate was added in one portion. The reaction was carried out at 160°C for 3 hours, then 7.8 g of siloxane phosphonic acid was added. After a colorimetric test confirmed neutralization of the catalyst, the volatiles were removed under vacuum at 180°C for 2 hours.

[0151] ·analysis: o Viscosity = 249 mPa·s. The viscosity was measured using a cone-plate rheometer at 100 rpm and 25°C. o Nitrogen content = 0.36%, Nitrogen content was determined by potentiometry using perchloric acid. o Vinyl content = 0.53%, vinyl content determined by ethoxylation of vinyl functional groups and quantification using GC headspace.

[0152] LSR Composition The mixer is filled with: - Me2ViSiO, with a viscosity of 60,000 mPa·s 1 / 2 29 parts of dimethylpolysiloxane oil blocked at both ends - Me2ViSiO with a viscosity of 100,000 mPa s 1 / 2 29 parts of dimethylpolysiloxane blocked at both ends -Specific surface area measured by the BET method is 300m 2 26 parts fumed silica and 7 parts hexamethyldisilazane at 100 / g

[0153] The whole is heated at 70° C. for 1 hour with stirring, then devolatilized, cooled and stored as Base 1 of Composition 1.

[0154] Next, add this to 45 parts of base 1 using a speed mixer. - Platinum metal introduced in the form of an organometallic complex of 10% by weight of platinum metal diluted in vinyl oil, known as Karstedt's catalyst - Part 3: Dimethylpolysiloxane oil with vinyl groups in the chain and at the chain ends and a viscosity of 1,000 mPa·s - 2 parts of dimethylpolysiloxane oil with vinyl groups in the chain and at the chain ends and a viscosity of 400 mPa·s

[0155] The composition designated LSR Composition 1 Part A is mixed in a speed mixer at 1,000 revolutions per minute for 1 minute. The Pt content is 10 ppm.

[0156] Next, add 45 parts of this base 1 in a speed mixer: - 1.3 parts of organohydrogenopolysiloxane M'Q resin containing Si-H groups 0.5 parts of a linear organohydrogenopolysiloxane containing Si-H groups in the chain and at the chain ends and containing about 20% by weight of Si-H groups - 1.5 parts of dimethylpolysiloxane oil with vinyl groups in the chain and at the chain ends and a viscosity of 400 mPa·s - 1.6 parts of dimethylpolysiloxane oil with vinyl groups in the chain and at the chain ends and a viscosity of 1000 mPa·s - 0.08 parts of ethynyl-1-cyclohexanol-1 as a crosslinking inhibitor

[0157] The composition designated LSR Composition 1 Part B is mixed in a Speedmixer at 1,000 revolutions per minute for 1 minute.

[0158] Then, using a speed mixer, add equal amounts of thixotropic additive D to parts A and B. Then, mix parts A and B in a 1:1 ratio.

[0159] RTV composition [Table 2]

[0160] Properties of LSR Compositions 3D printing suitability The yield stress was determined by rotational shear measurements at 25 °C using a Haake Mars rheometer with a cone-plate geometry of 20 mm diameter and a cone angle of 2°. The rotational shear measurements were performed as follows: from 0 to 20 s -1 Up to 120 seconds, 20 to 0 seconds -1 The measured stress is then plotted as a function of the applied shear stress. -1 Using the linear part of the yield stress (approximately 20 to 2.5s -1 A linear regression is performed on this linear portion of the curve to determine the yield stress corresponding to the intercept.

[0161] To evaluate the crosslinking and 3D printability of the compositions, part A and part B were printed using the extrusion printer LDM (Liquid Deposition Modeling Process) Deltatower with a 410 μm diameter conical nozzle, where possible, in cartridges, at 25 °C.

[0162] Crosslinking after storage is evaluated as follows: if the crosslinking rate after one month of storage is 80% or more of the nominal value measured initially at the same temperature, the composition may be considered stable ("OK" corresponds to Table 3).

[0163] 3D printability is evaluated as follows: while the silicone composition is being printed, each layer must retain its extruded shape without significant collapse in order to support the layer built on top. If slumping issues are identified, the printability of the silicone composition may be considered weak (corresponding to "No" in Table 3). If no slumping is observed, the printability of the silicone composition is considered strong (corresponding to "OK" in Table 3).

[0164] Table 3 summarizes the results obtained for the various compositions. [Table 3]

[0165] These results show that the compositions according to the invention can be loaded into cartridges and printed with a 3D printer (Examples 1-3 and 5-7). Conversely, if the nitrogen content in the composition is too high, the composition is not suitable for 3D printing because cross-linking problems occur (Example 4) and / or the yield stress is too high and the composition cannot be loaded into a cartridge (Example 8).

[0166] mechanical properties The mechanical properties of the resulting compositions were also tested. The tests were carried out on molded plates.

[0167] The hardness (Shore A) is determined according to the DIN 53505-A method.

[0168] The stress at break and the elongation at break were measured according to the NF ISO 37 method (2011 edition). Tests were performed on type 2 (H2) dumbbell shaped specimens. The tensile speed was 500 mm / min and measurements were performed at room temperature. An extensometer was used to measure the elongation at break.

[0169] The tear strength was determined according to ASTM D624 method, 2012 edition. The specimen shape was type A. The tensile speed was 500±50 mm / min, and the measurements were performed at room temperature.

[0170] The results obtained are summarized in Table 4. [Table 4]

[0171] These results show no change in the mechanical properties of the composition containing thixotropic agent D compared to the composition without thixotropic agent.

[0172] Crosslinking rate The crosslinking rates of the compositions according to Examples 2-4 were determined by rheometry at 115° C. using torsional oscillatory shear measurements in the range of 1.67 Hz and 0.5 according to ISO 6502. The results are shown in Table 5.

[0173] [Table 5]

[0174] These results show that the compositions according to the present invention (Examples 2-3) have a crosslinking rate high enough to be used for 3D printing. Conversely, when the nitrogen content in the composition is too high (Example 4), the crosslinking rate is too low to allow the composition to be used for 3D printing.

[0175] Properties of RTV Compositions 0.1% by weight DD The dynamic viscosity of the RTV n°1 compositions with and without (nitrogen content: 51 ppm) was measured at 25° C. using a Brookfield viscometer. The results are shown in Table 6.

[0176] [Table 6]

[0177] The results show that the composition according to the present invention has good rheological properties. In particular, when a low shear rate is applied, the composition has a high viscosity, and when a high shear rate is applied, the viscosity of the composition is significantly reduced. Therefore, the composition can be used for 3D printing. In fact, for successful printing, the silicone composition needs to flow at a controlled shear rate through a deposition head at moderate pressure and retain the extruded shape without significant slump.

[0178] To evaluate the crosslinking and 3D printability of RTV compositions n° 1 and 2, where possible, part A and part B were each loaded into a cartridge and printed at 25° C. using an extrusion printer LDM (Liquid Deposition Modeling Process) Deltatower with a 410 μm nozzle.

[0179] The results obtained for the various compositions are summarized in Table 7. [Table 7]

[0180] These results show that the composition according to the present invention can be printed with a 3D printer (Example 9). However, if the nitrogen content in the composition is too high, the composition is not suitable for 3D printing because of crosslinking problems after storage (Example 12). Furthermore, if the nitrogen content in the composition is too low, the composition cannot be printed using a 3D printer (Examples 10 and 11).

[0181] 3D Printing with RTV n°1 Composition The 3D printing was performed using a Delta Tower 3D printer containing a two-component Viscotec dosing system with a static mixer for the 2K silicone composition.

[0182] Part A and part B of the RTV n°1 composition were each placed into a cartridge. An elastomer article representing a 1 cm tall star wheel was printed using parts A and B, using a 200 μm nozzle at a speed of 10 mm / s.

[0183] The printed silicon starwheel has the same mechanical properties as the injected starwheel.

Claims

1. 1. A method for additive manufacturing of silicone elastomeric articles using a 3D printer selected from an extrusion 3D printer and a 3D jetting printer, the method comprising: 1) printing a crosslinkable silicone composition X onto a substrate to form a first layer; 2) printing said crosslinkable silicone composition X onto said first layer or a previous layer to form a subsequent layer; 3) optionally repeating step 2); and 4) crosslinking said first layer and subsequent layers, optionally by heating, to obtain a silicone elastomeric article; Including, The crosslinkable silicone composition X comprises: (A) at least one organopolysiloxane compound A containing per molecule at least two C2-C6 alkenyl radicals bonded to silicon atoms; (B) at least one organohydrogenopolysiloxane compound B containing per molecule at least two hydrogen atoms bonded to identical or different silicon atoms; (C) at least one catalyst C comprising at least one metal or compound from the platinum group; (D) at least one thixotropic agent D chosen from organosilicon compounds containing at least one cyclic amine function per molecule; (E) at least one filler E; and (F) optionally at least one crosslinking inhibitor F; Including, %.

2. 2. The method of claim 1, wherein the cyclic amine functional group of the thixotropic agent D is a piperidinyl functional group.

3. The thixotropic agent D has at least one unit of the general formula (D1) per molecule. (R) a (X) b ZSiO (3-(a+b)) / 2 (D1) is an organopolysiloxane having the formula: Where: each R symbol is the same or different and represents a monovalent hydrocarbon radical selected from the group consisting of linear or branched alkyl radicals having 1 to 6 carbon atoms, the phenyl radical and the 3,3,3-trifluoropropyl radical; each X symbol is the same or different and represents a monovalent radical selected from the group consisting of a hydroxyl group, an alkenyl radical having 2 to 6 carbon atoms, and an alkoxy radical having 1 to 6 carbon atoms; Z is a group of formula (I) 【Chemistry 1】 represents a group having a sterically hindered piperidinyl group of the formula: Where: - R 1 is a linear or branched alkylene radical having 2 to 18 carbon atoms; an alkylenecarbonyl radical in which the linear or branched alkylene moiety has 2 to 20 carbon atoms; an alkylenecyclohexylene radical in which the linear or branched alkylene moiety has 2 to 12 carbon atoms and the cyclohexylene moiety has an -OH group and, optionally, one or two alkyl radicals having 1 to 4 carbon atoms; 4 -O-R 5 - radical, R 4 and R 5 The radicals are identical or different and represent alkylene radicals having 1 to 12 carbon atoms; 4 -O-R 5 - radical, R 4 and R 5 Radicals have the above meanings, one or both of which are substituted by one or two OH groups; radicals of the formula -R 4 -COO-R 5 - and -R 4 -OCO-R 5 - radical, R 4 and R 5 is a radical having the above meaning; or a group of the formula -R 6 -O-R 7 -O-C-O-R 8 - radical, R 6 , R 7 and R 8 are the same or different and represent alkylene radicals having 2 to 12 carbon atoms; R 7 The radical is an optionally hydroxyl substituted radical; - U may be present or absent, and if present, U is -O- or -NR 9 - represents R 9 is a hydrogen atom; a linear or branched alkyl radical having 1 to 6 carbon atoms; a divalent radical -R 1 -, where one valence bond is -NR 9 - a radical connected at one end to a nitrogen atom of - and at the other end to a silicon atom; or 【Chemistry 2】 is a divalent radical of Here, R 1 has the above meaning, R 2 and R 3 has the following meaning, R 10 represents a linear or branched alkylene radical having 1 to 12 carbon atoms, and one of the valence bonds (R 10 The bond is -NR 9 - is bonded to the nitrogen atom of the other (R 1 bond) is bonded to the silicon atom; Each R 2 are the same or different and are derived from a linear or branched alkyl radical having 1 to 3 carbon atoms or a phenyl radical; R 3 is a hydrogen atom or R 2 represents a radical; a is a number selected from 0, 1 and 2; b is a number selected from 0, 1 and 2; and 3. The method according to claim 1, wherein a+b is at most 2.

4. The thixotropic agent D is represented by the formula (D3) (R) e (X) f Yes (4-(e+f)) / 2 (D3) Further containing other siloxyl units of: Where: R and X have the same meaning as given for formula (D1); e is a number selected from 0, 1, 2 and 3; f is a number selected from 0, 1, 2 and 3; and 4. The method according to claim 3, characterized in that e+f is at most 3.

5. The method according to any one of claims 1 to 4, characterized in that the crosslinkable silicone composition X has a yield stress of 400 to 3,000 Pa, preferably 450 to 2,500 Pa, more preferably 500 to 2,250 Pa.

6. The method of any one of claims 1 to 5, wherein the 3D printer is an extrusion printer.

7. A silicone elastomer article obtained by the method according to any one of claims 1 to 6.

8. A crosslinkable silicone composition X, (A) at least one organopolysiloxane compound A containing per molecule at least two C2-C6 alkenyl radicals bonded to silicon atoms; (B) at least one organohydrogenopolysiloxane compound B containing per molecule at least two hydrogen atoms bonded to identical or different silicon atoms; (C) at least one catalyst C comprising at least one metal or compound from the platinum group; (D) at least one thixotropic agent D chosen from organosilicon compounds containing at least one cyclic amine function per molecule; (E) at least one filler E; and (F) optionally at least one crosslinking inhibitor F; Including, The crosslinkable silicone composition X has a nitrogen content of 0.003 to 0.02% by weight, preferably 0.004 to 0.017% by weight, and more preferably 0.0045 to 0.016% by weight.

9. 9. The composition of claim 8, wherein the cyclic amine functional group of the thixotropic agent D is a piperidinyl functional group.

10. The thixotropic agent D has at least one unit of the general formula (D1) per molecule. (R) a (X) b ZSiO (3-(a+b)) / 2 (D1) is an organopolysiloxane having the formula: Where: each R symbol is the same or different and represents a monovalent hydrocarbon radical selected from the group consisting of linear or branched alkyl radicals having 1 to 6 carbon atoms, the phenyl radical and the 3,3,3-trifluoropropyl radical; each X symbol is the same or different and represents a monovalent radical selected from the group consisting of a hydroxyl group, an alkenyl radical having 2 to 6 carbon atoms, and an alkoxy radical having 1 to 6 carbon atoms; Z is a group of formula (I) 【Chemistry 3】 represents a group having a sterically hindered piperidinyl group; Where: - R 1 is a linear or branched alkylene radical having 2 to 18 carbon atoms; an alkylenecarbonyl radical in which the linear or branched alkylene moiety has 2 to 20 carbon atoms; an alkylenecyclohexylene radical in which the linear or branched alkylene moiety has 2 to 12 carbon atoms and the cyclohexylene moiety has an -OH group and, optionally, one or two alkyl radicals having 1 to 4 carbon atoms; 4 -O-R 5 - radical, R 4 and R 5 The radicals are identical or different and represent alkylene radicals having 1 to 12 carbon atoms; 4 -O-R 5 - radical, R 4 and R 5 Radicals have the above meanings, one or both of which are substituted by one or two OH groups; radicals of the formula -R 4 -COO-R 5 - and -R 4 -OCO-R 5 - radical, R 4 and R 5 is a radical having the above meaning; or a group of the formula -R 6 -O-R 7 -O-C-O-R 8 - radical, R 6 , R 7 and R 8 are the same or different and represent alkylene radicals having 2 to 12 carbon atoms; R 7 the radical is an optionally hydroxyl substituted radical; - U may be present or absent, and if present, U is -O- or -NR 9 - represents R 9 is a hydrogen atom; a linear or branched alkyl radical having 1 to 6 carbon atoms; a divalent radical -R 1 -, where one valence bond is -NR 9 - a radical connected at one end to a nitrogen atom of - and at the other end to a silicon atom; or 【Chemistry 4】 a divalent radical of: Here, R 1 has the above meaning, R 2 and R 3 has the following meaning, R 10 represents a linear or branched alkylene radical having 1 to 12 carbon atoms, and one of the valence bonds (R 10 The bond is -NR 9 - is bonded to the nitrogen atom of the other (R 1 bond) is bonded to the silicon atom; Each R 2 are the same or different and are derived from a linear or branched alkyl radical having 1 to 3 carbon atoms or a phenyl radical; R 3 is a hydrogen atom or R 2 represents a radical; a is a number selected from 0, 1 and 2; b is a number selected from 0, 1 and 2; and 10. The composition according to claim 8 or 9, characterized in that a+b is at most 2.

11. A composition according to any one of claims 8 to 10, characterized in that the crosslinkable silicone composition X has a yield stress of 400 to 3,000 Pa, preferably 450 to 2,500 Pa, more preferably 500 to 2,250 Pa.

12. A silicone elastomer article obtained by crosslinking the crosslinkable silicone composition X according to any one of claims 8 to 11.

13. Use of the crosslinkable silicone composition X according to any one of claims 8 to 11 for the additive manufacturing of silicone elastomer articles using a 3D printer selected from an extrusion 3D printer and a 3D injection printer.

14. Formula (D7) 【Chemistry 5】 Organopolysiloxane of the formula: Where: each R symbol is the same or different and represents a monovalent hydrocarbon radical selected from the group consisting of linear or branched alkyl radicals having 1 to 6 carbon atoms, the phenyl radical and the 3,3,3-trifluoropropyl radical; - each X 1 the symbols may be the same or different and represent an alkenyl radical having 2 to 6 carbon atoms; Z is a group of formula (I) 【Chemistry 6】 represents a group having a sterically hindered piperidinyl group; Where: - R 1 is a linear or branched alkylene radical having 2 to 18 carbon atoms; an alkylenecarbonyl radical in which the linear or branched alkylene moiety has 2 to 20 carbon atoms; an alkylenecyclohexylene radical in which the linear or branched alkylene moiety has 2 to 12 carbon atoms and the cyclohexylene moiety has an -OH group and, optionally, one or two alkyl radicals having 1 to 4 carbon atoms; 4 -O-R 5 - radical, R 4 and R 5 The radicals are identical or different and represent alkylene radicals having 1 to 12 carbon atoms; 4 -O-R 5 - radical, R 4 and R 5 Radicals have the above meanings, one or both of which are substituted by one or two OH groups; radicals of the formula -R 4 -COO-R 5 - and -R 4 -OCO-R 5 - radical, R 4 and R 5 is a radical having the above meaning; or a group of the formula -R 6 -O-R 7 -O-C-O-R 8 - radical, R 6 , R 7 and R 8 are the same or different and represent alkylene radicals having 2 to 12 carbon atoms; R 7 The radical is an optionally hydroxyl substituted radical; - U may be present or absent, and if present, U is -O- or -NR 9 - represents R 9 is a hydrogen atom; a linear or branched alkyl radical having 1 to 6 carbon atoms; a divalent radical -R 1 -, where one valence bond is -NR 9 - a radical connected at one end to a nitrogen atom of - and at the other end to a silicon atom; or 【Chemistry 7】 a divalent radical of: Here, R 1 has the above meaning, R 2 and R 3 has the following meaning, R 10 represents a linear or branched alkylene radical having 1 to 12 carbon atoms, and one of the valence bonds (R 10 The bond is -NR 9 - is bonded to the nitrogen atom of the other (R 1 bond) is bonded to the silicon atom; Each R 2 are the same or different and are derived from a linear or branched alkyl radical having 1 to 3 carbon atoms or a phenyl radical; R 3 is a hydrogen atom or R 2 represents a radical; m is between 0 and 2,000, preferably between 1 and 1,700, more preferably between 75 and 1,600, and an organopolysiloxane, characterized in that n is between 1 and 50, preferably between 1 and 25, and more preferably between 2 and 20;

15. The organic polysiloxane is represented by the formula (D7'): 【Chemistry 8】 and where m is from 0 to 2,000, preferably from 1 to 1,700, more preferably from 75 to 1,600, even more preferably m is 100; 15. The organopolysiloxane of claim 14, wherein n is from 1 to 50, preferably from 1 to 25, more preferably from 2 to 20, even more preferably n is 2.

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