Methods for manufacturing silicone elastomer products using 3D printers

Abstract

This invention relates to a method for manufacturing silicone elastomer articles, comprising the following steps: 1) providing a composition C comprising water, at least one poloxamer, and a poly(alkylene oxide glycol) into a container; 2) placing the container containing composition C at a desired temperature T1 to form a gel; 3) using a 3D printer to print a crosslinkable silicone composition X into the gel obtained in 2) at the desired temperature T1; 4) optionally, partially or completely crosslinking the printed composition X in the container, optionally by heating, to obtain a silicone elastomer article; 5) optionally, placing the container obtained in step 4) at a temperature T3 below the sol-gel transition temperature of composition C; 6) recovering the silicone elastomer article; and 7) optionally, washing the obtained silicone elastomer article, for example using water at a temperature T3 below the sol-gel transition temperature of composition C.

Description

Technical Field

[0001] This invention relates to a method for manufacturing silicone elastomer articles using a 3D printer. The invention also relates to silicone elastomer articles that can be obtained by this method. Background Technology

[0002] In 3D printing, the gravity, rheological, and mechanical properties of the compositions used for printing, especially for manufacturing complex articles, have a significant impact. In particular, low-viscosity silicone compositions ( <100000 mPa·s) makes it impossible to print simple or complex objects in a typical atmosphere with "Earth's" gravity. In fact, the rheological and mechanical properties of these silicones do not allow users to hold the object during printing. Furthermore, atmospheric pressure and surface tension make filament extrusion difficult. For medium or high viscosity (> The printability of silicone formulations with a pressure of 100,000 mPa·s depends on rheological and mechanical properties. However, it is impossible to print articles with complex shapes (i.e., overhangs > 40°, bridges, or heights > 2 mm).

[0003] Freeform reversible embedding of suspended hydrogel (FRESH) is an additive manufacturing technique that enables the 3D printing of soft materials with low or no yield stress. The printed material is embedded in the material during the process until it solidifies. Based on the literature, FRESH's capabilities should include self-healing, reusability, suspension, thermal stability, and high-precision printing.

[0004] US20180057682 discloses the use of organic microgels obtained by blending diblock copolymer polystyrene-block ethylene / propylene (SEP) and triblock copolymer polystyrene-block ethylene / butene-block polystyrene (SEBS) in mineral oil as support materials for 3D printing. The rheological properties of this organic microgel can be tuned, utilizing interference conversion to facilitate its use in the 3D printing of silicone structures. The solidified portions must be removed from the organic microgel support material by sequential washing with a solvent (methanol) and a surfactant solution. This support material appears to be non-reusable.

[0005] Hinton et al. (Science Advances, 2015, Vol. 1, no. 8) also disclosed a method for printing silicone 3D objects using three different gels: Carbopol 940, ETD 2020, and Ultrez 30 (Lubrizol), which are cross-linked acrylic polymers. Carbopol 940 imparts the best surface appearance. However, Carbopol 940 requires precise pH and salt control, which would be a limitation for printing different types of silicone. Contrary to the title of the publication, this gel appears to be no longer used, as Carbopol 940 was diluted with a PBS (polybutadiene / styrene) solution to remove the printed silicone object after 15 minutes.

[0006] It is also known from WO2019215190 to use poloxamer gel as a constrained environment, which enables the printing of low-viscosity crosslinked compositions to obtain silicone elastomer articles. This gel makes it possible to print some objects. However, depending on the complexity of the object and the path of the printing nozzle, the static yield stress of the suspended hydrogel appears to be sometimes too high (200 Pa and 500 Pa for 23 wt% and 27 wt% formulations, respectively), causing the printing nozzle to bend and affecting printing accuracy.

[0007] Therefore, there is a need for a gel composition that can be used as a constrained environment for FRESH 3D printing and has improved self-healing properties, especially for printing complex objects.

[0008] Therefore, there is a need for a method for manufacturing silicone elastomer articles using a 3D printer, which can handle a wide variety of silicone elastomers. Summary of the Invention

[0009] The first object of the present invention is therefore to provide a gel composition that can be used as a constrained environment for FRESH 3D printing and has improved self-healing properties.

[0010] Another object of the present invention is to provide a method for manufacturing silicone elastomer articles using a 3D printer, which can use a wide variety of silicone compositions.

[0011] Another object of the present invention is to provide a method for manufacturing articles with complex shapes, namely articles with a sag > 40°, a bridge, or a height > 2 mm.

[0012] All these objectives are achieved by the present invention, which relates to a method for manufacturing silicone elastomer articles, comprising the following steps:

[0013] 1) Provide a composition C comprising water, at least one poloxamer and poly(alkylene oxide glycol) (also known as polyalkylene oxide) into a container;

[0014] 2) Place the container containing composition C at the desired temperature T1 to form a gel;

[0015] 3) Use a 3D printer to print the crosslinkable silicone composition X into the gel obtained in 2) at the required temperature T1;

[0016] 4) Optionally, the printed composition X is partially or completely crosslinked in the container, optionally by heating, to obtain a silicone elastomer article;

[0017] 5) Optionally, the container obtained in step 4) is placed at a temperature T3 below the sol-gel transition temperature of composition C;

[0018] 6) Recycle silicone elastomer products; and

[0019] 7) Optionally, the obtained silicone elastomer article is washed, for example, with water at a temperature T3 below the sol-gel transition temperature of composition C.

[0020] The poloxamer must be incompatible with the silicone elastomer, meaning there must be no interpenetration between the poloxamer and the silicone elastomer. This advantageously allows for obtaining a good surface roughness of the manufactured silicone article, i.e., a roughness of less than 100 nm.

[0021] Furthermore, poloxamer should be removed without contaminating the silicone surface of the product.

[0022] According to the present invention, poloxamer is a copolymer composed of poly(propylene oxide) (PO) and poly(ethylene oxide) (EO) blocks, also known as a poly(propylene oxide)-poly(ethylene oxide) block copolymer. Preferably, the poloxamer according to the present invention is a triblock copolymer composed of a central PO block and two terminal EO blocks, also known as a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer, that is, the poloxamer according to the present invention is preferably of the EO-PO-EO triblock copolymer type.

[0023] A key property of poloxamers is their ability to form a gel with water during the sol-gel transition temperature. At this temperature, the rheological properties of the composition change from a liquid to a solid state. Aqueous solutions of poloxamers are liquid at low temperatures and form gels in a thermally reversible process at higher temperatures. The transitions occurring in these systems depend on the poloxamer and its concentration. In this invention, temperature T1 corresponds to the temperature at which composition C forms a gel, while temperature T3 is a temperature below which the gel formed by composition C in step 2 liquefies.

[0024] Preferably, in this invention, the poloxamer composition C is solid at ambient temperature, i.e., at a temperature of 20-30°C, and liquid at a lower temperature, i.e., below 15°C. Preferably, in this invention, the poloxamer is composed of poly(propylene oxide) (PO) and poly(ethylene oxide) (EO) blocks. Preferably, the poloxamer of this invention is a triblock copolymer composed of a central PO block and two terminal EO blocks, and contains 25-90% by weight of EO units based on the total weight of the poloxamer, preferably 30-80% by weight of EO units based on the total weight of the poloxamer, and more preferably 50-75% by weight of EO units based on the total weight of the poloxamer.

[0025] More preferably, the poloxamer according to the invention is a triblock copolymer composed of a central PO block and two terminal EO blocks, wherein each of the two EO blocks contains 20-300 repeating units, preferably 50-150 repeating units, and the PO block contains 10-100 repeating units, preferably 30-70 repeating units.

[0026] Advantageously, the poloxamer of the present invention is a triblock copolymer consisting of a central PO block and two terminal EO blocks, wherein it has 70% + / - 2% by weight of EO units.

[0027] In a preferred embodiment, the poloxamer according to the invention is a triblock copolymer consisting of a central PO block and two terminal EO blocks, wherein each of the two EO blocks contains 100+ / -10 repeating units, and the PO block contains 55+ / -10 repeating units. Such poloxamers are, for example, produced by BASF under the name Pluronic. sell.

[0028] Moreover, polosham, especially Pluronic It is biocompatible and therefore can be used to prepare products for biological or medical purposes.

[0029] The poly(alkylene oxide glycol) (PAG) of the present invention is preferably a poly(alkylene oxide glycol) with a molecular weight (Mw) of 100-6000 g / mol, more preferably 200-2000 g / mol.

[0030] Unbound by any theory, the poly(alkylene oxide glycol) is preferably selected based on the external blocks of poloxamer. Preferably, the poly(alkylene oxide glycol) should have the same properties as the external blocks of poloxamer, which means that the alkylene groups of the poly(alkylene oxide glycol) are the same as those of the external blocks of poloxamer.

[0031] Before adding poloxamer, the poly(alkylene oxide glycol) (which is in liquid or powder form depending on the molecular weight) is dispersed in water.

[0032] Preferably, the poly(alkylene oxide glycol) of the present invention is poly(ethylene oxide glycol) (or polyethylene oxide, PEG), preferably PEG with a molecular weight (Mw) of 100-6000 g / mol, more preferably 200-2000 g / mol.

[0033] In the composition (C) of the present invention, poloxamer is preferably a triblock copolymer consisting of a central PO block and two terminal EO blocks, and the poly(alkylene oxide glycol) is preferably PEG having a molecular weight (Mw) of 100-6000 g / mol, preferably 200-2000 g / mol.

[0034] Unbound by any theory, the gel formed by composition C acts as a constrained environment, enabling the printing of low-viscosity crosslinked composition X to further obtain silicone elastomer articles. In practice, the gel formed by composition C applies a constant pressure to the crosslinked composition X during printing, which prevents any material degradation. The applied pressure can be measured using the yield stress parameter of Bingham fluid as a rheological characterization (shear stress versus shear rate), preferably in the range of 1-10 kPa.

[0035] Advantageously, the gel formed by composition C is self-healing. This advantageously allows the printing nozzle to repeatedly pass through the gel in the same area, while the gel simultaneously supports the printed structure.

[0036] Advantageously, the poly(alkylene oxide diol) added to the poloxamer aqueous composition acts as a softener for the formed gel, enabling better self-healing while maintaining and improving the properties of the gel for fresh 3D printing. In fact, the addition of PAG (a yield stress modifier) ​​allows for the adjustment of rheological properties and enables a reduction in gelation temperature, yield stress, and viscosity. Lowering and controlling the static yield stress allows the hydrogel to self-heal better during the process while maintaining the suspension of the printed object.

[0037] Preferably, the static yield stress of gel C at a temperature of 20°C-50°C, preferably 20-40°C, is 1-100 Pa, more preferably 1-50 Pa. The static yield stress can be measured according to any method known to those skilled in the art, particularly using a controlled stress rheometer (DHR-2 rheometer, TA Instruments, USA) with a concentric cylindrical geometry of 14 mm radius and 42 mm height for rheological measurements. 15 mL of composition C is introduced with a fixed gap of 3580 μm. First, the gelation temperature (Tg) is obtained by a frequency sweep program (0.1-100 rad / s) after a linear field check. gel The gelation temperature is determined when tanδ = G” / G' = 1. Then, by applying 10 to 10... -5 s -1 The static yield stress was measured by scanning the shear rate and measuring the stress at different temperatures (10 to 40 °C, in 5 °C increments). The viscosity of the silicone material was measured using a cone-plate geometry with a radius of 40 mm, an angle of 2 °C, and a gap of 50 μm.

[0038] Preferably, the weight ratio of PAG / poloxamer results in a static yield stress of 0.5-200 Pa, preferably 1-100 Pa, and more preferably 1-50 Pa for gel C at a temperature of 20-50°C, more preferably 20-40°C.

[0039] Preferably, the weight ratio of PAG / poloxam is greater than 0.5, more preferably greater than 1. It is more preferably 0.5-2, more preferably 0.5-1.5, more preferably 1-2, and more preferably 1.1-1.5.

[0040] Preferably, composition C contains 10-40% by weight, more preferably 15-30% by weight, or even more preferably 17-25% by weight of at least one poloxamer, and more preferably at least one poloxamer as described above.

[0041] In the composition (C) of the present invention, poloxamer is preferably a triblock copolymer consisting of a central PO block and two terminal EO blocks, and the poly(alkylene oxide glycol) is preferably PEG having a molecular weight (Mw) of 100-6000 g / mol, preferably 200-2000 g / mol, preferably 400 g / mol, and the weight ratio of PEG / poloxam is greater than 1, preferably 1-2, preferably 1.1-1.5.

[0042] Advantageously, in order to provide functionalization of the surface of the silicone elastomer article obtained by the method of the present invention, composition C may further comprise one or more compounds selected from:

[0043] - Bases, such as NaOH;

[0044] - Acids, such as acetic acid;

[0045] - Functionalized silanes, for example, those having amino, epoxy, hydroxyl, or polyether groups (especially stable at pH 4-5).

[0046] In step 1, composition C is placed at a temperature T1 that allows gel formation. Those skilled in the art can determine this temperature range based on their common sense and the poloxamer used. Preferably, T1 is 20-50°C, more preferably 25-50°C, more preferably 25-40°C, for example 25-35°C, and even more preferably 28-32°C.

[0047] Composition C can be obtained by dispersing a poly(alkylene oxide) glycol in water and then adding poloxamer.

[0048] In the method according to the invention, composition X is a crosslinkable silicone composition, preferably having a viscosity of 1000 mPa·s to 1000000 mPa·s. The method according to the invention is particularly suitable for printing crosslinkable silicone compositions X with a viscosity of less than 50000 mPa·s, preferably less than 10000 mPa·s, for example 1000-5000 mPa·s.

[0049] All viscosities considered in this specification correspond to “Newtonian” dynamic viscosity at 25°C, i.e., dynamic viscosity measured in a manner known per se using a Brookfield viscometer at a sufficiently low shear rate gradient that makes the measured viscosity independent of the velocity gradient.

[0050] The crosslinkable organosilicon composition X can be a crosslinkable organosilicon composition that can be crosslinked through addition reaction or polycondensation reaction.

[0051] In one embodiment, the crosslinkable silicone composition X is a crosslinkable silicone composition obtained through an addition reaction. In this embodiment, composition X comprises:

[0052] (A) At least one organopolysiloxane compound A, each molecule of which contains at least two C2-C6 alkenyl groups bonded to silicon atoms.

[0053] (B) At least one organohydrogen-based polysiloxane compound B, each molecule of which contains at least two hydrogen atoms bonded to the same or different silicon atoms.

[0054] (C) At least one catalyst, Cat, which is composed of at least one platinum group metal or compound.

[0055] (D) Optionally, packing D, and

[0056] (F) Optionally, crosslinking inhibitor F.

[0057] Organopolysiloxane A

[0058] According to a particularly advantageous manner, organopolysiloxane A, comprising at least two C2-C6 alkenyl groups bonded to silicon atoms per molecule, includes:

[0059] (i) At least two silyloxy units (A.1), which may be the same or different, having the following formula:

[0060]

[0061] in:

[0062] -a = 1 or 2, b = 0, 1 or 2 and a + b = 1, 2 or 3;

[0063] - The symbol W can be the same or different, representing linear or branched C2-C6 alkenyl groups.

[0064] - And the symbol Z can be the same or different, representing a monovalent hydrocarbon group containing 1-30 carbon atoms, preferably selected from alkyl groups containing 1-8 carbon atoms and aryl groups containing 6-12 carbon atoms, and even more preferably selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl.

[0065] (ii) and optionally, at least one silyloxy unit having the following formula:

[0066]

[0067] in:

[0068] -a = 0, 1, 2, or 3,

[0069] - Symbol Z 1They may be the same or different, representing a monovalent hydrocarbon group containing 1-30 carbon atoms, preferably selected from alkyl groups containing 1-8 carbon atoms and aryl groups containing 6-12 carbon atoms, and even more preferably selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl.

[0070] Advantageously, Z and Z 1 W is selected from methyl and phenyl, and W is selected from the following: vinyl, propenyl, 3-butenyl, 5-hexenyl, 9-decenyl, 10-undecenyl, 5,9-decadienyl and 6-11-dodecadienyl, and preferably, W is vinyl.

[0071] In a preferred embodiment, in equation (A.1), a = 1 and a + b = 2 or 3, and in equation (A.2), c = 2 or 3.

[0072] These organopolysiloxanes A can have linear, branched, or cyclic structures. Their degree of polymerization is preferably 2-5000.

[0073] When they are linear polymers, they are essentially formed from the following units: silanoxy units D, selected from silanoxy units W₂SiO₃. 2 / 2 WZSiO 2 / 2 and Z 1 2SiO 2 / 2 And the silyloxy unit M, selected from the silyloxy unit W3SiO 1 / 2 WZ2SiO 1 / 2 W2ZSiO 1 / 2 and Z 1 3SiO 1 / 2 Symbols W, Z, and Z 1 As stated above.

[0074] Examples of the terminal unit M may include trimethylsilyloxy, dimethylphenylsilyloxy, dimethylvinylsilyloxy, or dimethylhexenylsilyloxy groups.

[0075] As an example of unit D, dimethylsiloxy, methylphenylsiloxy, methylvinylsiloxy, methylbutenylsiloxy, methylhexenylsiloxy, methyldecenylsiloxy, or methyldecadienylsiloxy groups may be mentioned.

[0076] The organopolysiloxane A can be an oil with a dynamic viscosity of approximately 10-1,000,000 mPa·s at 25°C, typically approximately 1,000-120,000 mPa·s at 25°C.

[0077] When they are cyclic organopolysiloxanes, they can be formed from the silanoxy unit D of the following formula: W₂SiO₃ 2 / 2 Z2SiO 2 / 2 or WZSiO 2 / 2 It can be of the dialkylsiloxy, alkylarylsiloxy, alkylvinylsiloxy, or alkylsiloxy type. Examples of such siloxy units have been mentioned above. The cyclic organopolysiloxane A has a viscosity of approximately 1-5000 mPa·s at 25°C.

[0078] Preferably, the organopolysiloxane compound A has a mass content of 0.001-30%, more preferably 0.01-10%, of Si-vinyl units.

[0079] Organohydrogen-based polysiloxane B

[0080] According to a preferred embodiment, organohydrogen-based polysiloxane compound B is an organopolysiloxane containing at least two hydrogen atoms per molecule bonded to the same or different silicon atoms, and preferably at least three hydrogen atoms per molecule directly bonded to the same or different silicon atoms.

[0081] Advantageously, organohydrogen-based polysiloxane compound B is an organopolysiloxane comprising:

[0082] (i) Having at least two silyloxy units and preferably at least three silyloxy units of the following formula:

[0083]

[0084] in:

[0085] -d = 1 or 2, e = 0, 1 or 2, and d + e = 1, 2 or 3.

[0086] - Symbol Z 3 These may be the same or different, representing a monovalent hydrocarbon group containing 1-30 carbon atoms, preferably selected from alkyl groups containing 1-8 carbon atoms and aryl groups containing 6-12 carbon atoms, and even more preferably selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl, and phenyl, and...

[0087] (ii) Optionally, at least one silyloxy unit having the following formula:

[0088]

[0089] in:

[0090] -c = 0, 1, 2, or 3,

[0091] - Symbol Z 2They may be the same or different, representing a monovalent hydrocarbon group containing 1-30 carbon atoms, preferably selected from alkyl groups containing 1-8 carbon atoms and aryl groups containing 6-12 carbon atoms, and even more preferably selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl.

[0092] The organohydrogen-based polysiloxane compound B may be formed solely from the silanoxy 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 5000.

[0093] Examples of the silanoxy unit of formula (B.1) are particularly the following unit: H(CH3)2SiO 1 / 2 HCH3SiO 2 / 2 and H(C6H5)SiO 2 / 2 .

[0094] When they are linear polymers, they are essentially formed from the following units:

[0095] -Silyloxy group D, selected from units having the following formula: Z 2 2SiO 2 / 2 or Z 3 HSiO 2 / 2 ,as well as

[0096] -Silyloxy unit M, selected from units having the following formula: Z 2 3SiO 1 / 2 Or Z 3 2HSiO 1 / 2 ,

[0097] symbol Z 2 and Z 3 As stated above.

[0098] These linear organopolysiloxanes can be oils with a dynamic viscosity of about 1-100,000 mPa·s at 25°C, typically about 10-5,000 mPa·s at 25°C, or high-viscosity oils with a viscosity of about 1,000,000 mPa·s or greater at 25°C.

[0099] When they are cyclic organopolysiloxanes, they are composed of molecules having the following formula Z 2 2SiO 2 / 2 and Z 3 HSiO 2 / 2 The silyloxy unit D is formed, which can be of the dialkylsilyloxy or alkylarylsilyloxy type, or only of unit Z. 3 HSiO 2 / 2They are formed. They have a viscosity of approximately 1-5000 mPa·s.

[0100] Examples of linear organohydrogen-based polysiloxane compounds B are: dimethyl polysiloxanes with dimethylsilyl end groups, dimethylhydromethyl polysiloxanes with trimethylsilyl end groups, dimethylhydromethyl polysiloxanes with dimethylsilyl end groups, hydromethyl polysiloxanes with trimethylsilyl end groups, and cyclic hydromethyl polysiloxanes.

[0101] As organohydrogen-based polysiloxane compounds B, oligomers and polymers corresponding to general formula (B.3) are particularly preferred:

[0102]

[0103] in:

[0104] -x and y are integers between 0 and 200.

[0105] - Symbol R 1 They can be the same or different, and can be represented independently of each other:

[0106] • A linear or branched alkyl group comprising 1-8 carbon atoms, optionally substituted with at least one halogen, preferably fluorine, wherein the alkyl group is preferably methyl, ethyl, propyl, octyl, or 3,3,3-trifluoropropyl.

[0107] • Cycloalkyl groups containing 5-8 carbon atoms

[0108] • An aryl group containing 6-12 carbon atoms, or

[0109] • Alkaryl groups containing an alkyl moiety of 5-14 carbon atoms and an aryl moiety of 6-12 carbon atoms.

[0110] As organohydrogen-based polysiloxane compound B, the following compounds are particularly suitable for this invention:

[0111]

[0112] Where a, b, c, d, and e are defined as follows:

[0113] -In the polymer of formula S1:

[0114] -0≤a≤150, preferably 0≤a≤100, and more particularly 0≤a≤20, and

[0115] -1≤b≤90, preferably 10≤b≤80, and more specifically 30≤b≤70.

[0116] - In the polymer of formula S2: 0 ≤ c ≤ 15

[0117] - In the polymer of formula S3: 5≤d≤200, preferably 20≤d≤100, and 2≤e≤90, preferably 10≤e≤70.

[0118] In particular, the organohydrogen-based polysiloxane compound B suitable for use in the present invention is a compound of formula S1, wherein a = 0.

[0119] Preferably, the organohydrogen-based polysiloxane compound B has a SiH unit content of 0.2-91%, preferably 0.2-50%.

[0120] In one embodiment, the organohydrogen-based polysiloxane compound B is a branched polymer. The branched organohydrogen-based polysiloxane compound B comprises...

[0121] a) At least two distinct silyloxy units selected from the following: formula R3SiO 1 / 2 The silaneoxy unit M, formula R2SiO 2 / 2 The silaneoxy unit D, formula RSiO 3 / 2 The silaneoxy unit T and the formula SiO 4 / 2 The silyloxy unit Q, where R represents a monovalent hydrocarbon group having 1-20 carbon atoms or a hydrogen atom, and

[0122] (b) The condition is that at least one of these siloxy units is a siloxy unit T or Q, and at least one of the siloxy units M, D or T contains a Si-H group.

[0123] Therefore, according to a preferred embodiment, the branched organohydrogen-based polysiloxane compound B can be selected from the group consisting of:

[0124] The organopolysiloxane resin of formula M'Q is essentially formed from the following units:

[0125] (a) Equation R2HSiO 1 / 2 The monovalent silyloxy group M'; and

[0126] (b) SiO 4 / 2 The tetravalent siloxy unit Q; and

[0127] The organopolysiloxane resin of formula MD'Q is essentially formed from the following units:

[0128] (a) Formula RHSiO 2 / 2 The divalent silyloxy group D';

[0129] (b) Formula R3SiO 1 / 2 The monovalent silyloxy unit M; and

[0130] (c) SiO4 / 2 The tetravalent silyloxy group Q;

[0131] Wherein R represents a monovalent hydrocarbon group having 1-20 carbon atoms, preferably a monovalent aliphatic or aromatic hydrocarbon group having 1-12 carbon atoms, more preferably 1-8 carbon atoms.

[0132] As another embodiment, a mixture of at least one linear organohydrogen-based polysiloxane compound B and at least one branched organohydrogen-based polysiloxane compound B can be used. In this case, the linear and branched organohydrogen-based polysiloxane compounds B can be mixed in any proportion over a wide range, and the mixing ratio can be adjusted according to desired product properties such as hardness and the ratio of Si-H to alkenyl groups.

[0133] In the context of this invention, the ratio of organopolysiloxane A to organohydrogen-based polysiloxane B is such that the molar ratio of hydrogen atoms (Si-H) bonded to silicon in organohydrogen-based polysiloxane B to alkenyl groups (Si-CH=CH2) bonded to silicon in organopolysiloxane A is 0.2 to 20, preferably 0.5 to 15, more preferably 0.5 to 10, and even more preferably 0.5 to 5.

[0134] Catalyst Cat

[0135] Catalysts composed of at least one metal or compound from the platinum group are well known. The platinum group metals are those known by the name platinoids, a term that includes ruthenium, rhodium, palladium, osmium, and iridium in addition to platinum. Platinum and rhodium compounds are preferred. In particular, complexes of organic products with platinum as described in the following documents are used: patents US A 3 159 601, US A 3 159 602, US A 3 220 972 and European patents EPA 0 057459, EPA 0 188 978 and EPA 0 190 530; and complexes of vinyl organosiloxanes with platinum as described in the following documents: US A 3 419 593, US A 3 715 334, US A 3 377 432 and US A 3 814 730. Specific examples include: platinum metal powder, chloroplatinic acid, complexes of chloroplatinic acid with β-diketone, complexes of chloroplatinic acid with olefins, complexes of chloroplatinic acid with 1,3-divinyltetramethyldisiloxane, complexes of organosilicon resin powder containing the above catalysts, rhodium compounds such as those represented by the following formulas: RhCl(Ph3P)3, RhCl3[S(C4H9)2]3, etc.; mixtures of tetra(triphenyl)palladium, palladium black, and triphenylphosphine, etc.

[0136] The platinum catalyst should preferably be used in sufficient quantities to allow for sufficiently rapid crosslinking at room temperature. Typically, 1-200 ppm by weight of catalyst, preferably 1-100 ppm by weight, and more preferably 1-50 ppm by weight, is used based on the amount of Pt metal relative to the total organosilicon composition.

[0137] Packing D

[0138] To achieve sufficiently high mechanical strength, the addition-crosslinked silicone composition includes fillers such as fine silica particles as reinforcing filler D. Precipitated silica and fumed silica, as well as mixtures thereof, can be used. The specific surface area of ​​these active reinforcing fillers should be at least 50 m². 2 / g, and preferably 100-400m 2 / g, as measured by the BET method. This type of active reinforcing filler is a well-known material in the field of silicone rubber. The silica filler can have hydrophilic properties or can be hydrophobized by known methods.

[0139] In a preferred embodiment, the silica-reinforced filler has a specific surface area of ​​at least 50 m². 2 / g and preferably 100-400m 2 / g of fumed silica, as measured by the BET method. Fumed silica can be used as is in its untreated form, but hydrophobic surface treatment is preferred. In those cases, if hydrophobic surface-treated fumed silica is used, either pre-treated fumed silica can be used, or a surface treatment agent can be added during mixing of the fumed silica with organopolysiloxane A to perform in-situ treatment of the fumed silica.

[0140] The surface treatment agent can be selected from any commonly used reagent, such as alkylalkoxysilanes, alkylchlorosilanes, alkylsilazanes, silane coupling agents, titanate-based treatment agents, and fatty acid esters. A single treatment agent or a combination of two or more treatment agents can be used, which can be used simultaneously or at different times.

[0141] The amount of silica reinforcing filler D in this addition-crosslinking silicone composition is 5-40% by weight of the total composition, preferably 10-35% by weight. If this blending amount is less than 5% by weight, sufficient elastomer strength may not be obtained, while if the blending amount exceeds 40% by weight, the actual blending process may become difficult.

[0142] The organosilicon compositions according to the present invention may also contain other fillers, such as standard semi-reinforced or filled fillers, hydroxyl-functional organosilicon resins, pigments, or adhesion promoters.

[0143] Non-siliceous minerals that can be included as semi-reinforcing or filling mineral fillers can be selected from: carbon black, titanium dioxide, alumina, hydrated alumina, calcium carbonate, ground quartz, diatomaceous earth, zinc oxide, mica, talc, iron oxide, barium sulfate, and quicklime.

[0144] Organosilicon resins refer to organopolysiloxanes containing at least one T and / or one Q silanoxy unit, wherein Q: SiO 2 / 2 And T: R1SiO 3 / 2 Hydroxyl-functionalized 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)R1SiO 2 / 2 The R1, R2, and R3 groups are independently selected from:

[0145] - A linear or branched alkyl group having 1-8 carbon atoms, including the terminal atoms, which may optionally be substituted with one or more halogen atoms; and

[0146] - Aryl or alkyl aryl groups containing 6-14 carbon atoms, including the terminal value.

[0147] Preferably, the hydroxyl-functionalized organosilicon resin is MQ(OH) resin.

[0148] Crosslinking inhibitor F

[0149] In addition, crosslinking inhibitors are commonly used in crosslinked silicone compositions to slow down the curing of the composition at ambient temperature. Crosslinking inhibitor F can be selected from the following compounds:

[0150] -Alkynes

[0151] - An organopolysiloxane substituted with at least one alkenyl group, which may optionally be in cyclic form, with tetramethylvinylcyclotetrasiloxane being particularly preferred.

[0152] -pyridine,

[0153] - Organophosphorus and phosphites,

[0154] -unsaturated amides, and

[0155] - Maleic alkyl or alkenyl esters.

[0156] These alkynyl alcohols (see FR-B-1 528 464 and FR-A-2 372 874) are preferred heat-sealing inhibitors for hydrosilylation reactions and have the following formula:

[0157] (R')(R”)(OH)CC≡CH

[0158] Wherein: R' is a linear or branched alkyl group, or a phenyl group; and -R” is H or a linear or branched alkyl group, or a phenyl group; groups R' and R” and the carbon atom at the α position relative to the triple bond may form a ring.

[0159] The total number of carbon atoms contained in R' and R” is at least 5, and preferably 9-20. Examples of alkynyl alcohols that may be mentioned include:

[0160] -1-Ethynyl-1-cyclohexanol;

[0161] -3-Methyl-1-dodecyn-3-ol;

[0162] -3,7,11-trimethyl-1-dodecyn-3-ol;

[0163] -1,1-Diphenyl-2-propyn-1-ol;

[0164] -3-Ethyl-6-ethyl-1-nonyne-3-ol;

[0165] -2-Methyl-3-butyn-2-ol;

[0166] 3-Methyl-1-pentadenylen-3-ol; and

[0167] - diallyl maleate or diallyl maleate derivatives.

[0168] In a preferred embodiment, the crosslinking inhibitor is 1-ethynyl-1-cyclohexanol.

[0169] To achieve 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 this silicone composition is sufficient to slow down the curing of the composition at ambient temperature. This concentration will vary widely depending on the specific inhibitor used, the nature and concentration of the hydrosilylation catalyst, and the nature of the organohydrogen-based polysiloxane. In some cases, an inhibitor concentration as low as one mole of inhibitor per mole of platinum group metal will produce satisfactory storage stability and curing rate. In other cases, an inhibitor concentration of up to 500 moles or more of inhibitor per mole of platinum group metal may be required. The optimal concentration of inhibitor in a given silicone composition can be readily determined through routine experiments.

[0170] Advantageously, the amount of crosslinking inhibitor F in the addition-crosslinking silicone composition is 0.01%-0.2% by weight, preferably 0.03%-0.15% by weight, relative to the total weight of the silicone composition.

[0171] The use of inhibitors effectively prevents premature curing of the silicone composition at the nozzle tip and subsequent damage to the printed layer.

[0172] Optionally, the silicone composition X may further comprise a thixotropic agent. This thixotropic agent may be an organopolysiloxane-polyoxyalkylene copolymer F.

[0173] Organopolysiloxane-polyalkylene oxide copolymer F, also known as polydiorganosiloxane-polyether copolymer or polyalkylene oxide-modified polymethylsiloxane, is an organopolysiloxane containing silanoxy units with alkylene oxide chain sequences. Preferably, organopolysiloxane-polyalkylene oxide copolymer F is an organopolysiloxane containing silanoxy units with ethylene oxide chain sequences and / or propylene oxide chain sequences.

[0174] In a preferred embodiment, the organopolysiloxane-polyalkylene copolymer F is an organopolysiloxane comprising a silanoxy group of the following formula (F-1):

[0175] [R 1 a Z b SiO (4-a-b) / 2 ] n (F-1)

[0176] in

[0177] Each R 1 The group is independently selected from hydrocarbon groups containing 1 to 30 carbon atoms, preferably from alkyl groups containing 1 to 8 carbon atoms and aryl groups containing 6 to 12 carbon atoms;

[0178] Each Z represents a group -R 2 -(OC p H 2p ) q (OC r H 2r ) s -OR 3 ,

[0179] in

[0180] n is an integer greater than 2;

[0181] a and b are independently 0, 1, 2, or 3, and a + b = 0, 1, 2, or 3.

[0182] R 2 It consists of divalent hydrocarbon groups or direct bonds with 2-20 carbon atoms;

[0183] R 3 For hydrogen atoms or for R 1 Defined groups;

[0184] p and r are independent integers from 1 to 6;

[0185] q and s are independently 0 or integers, such that 1 <q+s<400;

[0186] Furthermore, each molecule of the organopolysiloxane-polyoxyalkylene copolymer E contains at least one group Z.

[0187] In a preferred embodiment, in the above formula (F-1):

[0188] n is an integer greater than 2; and a + b = 0, 1, 2, or 3.

[0189] a and b are independently 0, 1, 2, or 3.

[0190] R 1 It is an alkyl group with 1-8 carbon atoms including the terminal value, most preferably, R 1 It is methyl.

[0191] R 2 It consists of a divalent hydrocarbon group or a direct bond with 2-6 carbon atoms;

[0192] p = 2 and r = 3,

[0193] q is between 1 and 40, with the optimal value between 5 and 30.

[0194] The value of s is between 1 and 40, with the optimal value between 5 and 30.

[0195] And R 3 It is a hydrogen atom or an alkyl group with 1-8 carbon atoms including the terminal value, with R being the most preferred. 3 It is a hydrogen atom.

[0196] In a most preferred embodiment, the organopolysiloxane-polyoxyalkylene copolymer F is an organopolysiloxane containing a total of 1-200, preferably 50-150, silanoxy units (F-1) and a total of 2-25, preferably 3-15, Z groups.

[0197] An example of an organopolysiloxane-polyoxyalkylene copolymer F that can be used in the method of the present invention corresponds to formula (F-2).

[0198] R a 3SiO[R a 2SiO] t [R a Si(R b -(OCH2CH2) x (OC3H6) y -OR c )O] r SiRa 3 (F-2)

[0199] in

[0200] Each R a Independently selected from alkyl groups containing 1-8 carbon atoms, and preferably, R a It is methyl.

[0201] Each R b It is a divalent hydrocarbon group or a direct bond having 2-6 carbon atoms, and preferably, R b It is propyl.

[0202] x and y are independent integers from 1 to 40, preferably from 5 to 30, and most preferably from 10 to 30.

[0203] t is 1-200, preferably 25-150.

[0204] r is 2-25, preferably 3-15, and

[0205] R c It is H or alkyl, preferably H or CH3 group.

[0206] Advantageously, in one embodiment, the organopolysiloxane-polyoxyalkylene copolymer F is:

[0207] Me3SiO[Me2SiO] 75 [MeSi((CH2)3-(OCH2CH2) 22 (OCH2CH(CH3)) 22 -OH)O]7SiMe3.

[0208] Methods for preparing polydiorganosiloxane-polyalkylene oxide copolymers are well known in the art. For example, polydiorganosiloxane-polyalkylene oxide copolymers can be prepared by a hydrosilylation reaction in the presence of a platinum-based catalyst, by reacting a polydiorganosiloxane, for example, containing silicon-bonded hydrogen atoms, with a polyalkylene oxide containing a group having aliphatic unsaturation.

[0209] The amount of organopolysiloxane-polyoxyalkylene copolymer F in the addition crosslinking organosilicon composition is at least 0.3% by weight, preferably at least 0.4% by weight, most preferably 0.6-4% by weight, and even more preferably 0.6%-3% by weight, relative to the total weight of the organosilicon composition.

[0210] In a preferred embodiment, the crosslinkable silicone composition X of the present invention comprises, per 100% by weight, the silicone composition:

[0211] -55-80% by weight of at least one organopolysiloxane compound A;

[0212] -0.1-5% by weight of at least one organohydrogen-based polysiloxane compound B;

[0213] -0-20% by weight of at least one filler, preferably reinforced silica filler D;

[0214] -0.002-0.01% by weight of platinum, and

[0215] -0.01-0.2% by weight of at least one crosslinking inhibitor E.

[0216] The composition may be a partial composition containing component AE in a single portion, or alternatively, a multipart composition containing these components in two or more portions, provided that components B and Cat are not present in the same portion. For example, a multipart composition may comprise a first portion and a second portion, the first portion containing a portion of component A and all of component Cat, and the second portion containing the remainder of component A and all of component B. In some embodiments, component A is in the first portion, component B is in the second portion separate from the first portion, and component Cat is in the first portion, the second portion, and / or a third portion separate from the first and second portions. Components D and E may be present together with at least one of components B or Cat in a respective portion (or portions), and / or may be in separate portions (or portions).

[0217] This partial composition is typically prepared by combining the main component and any optional components in the stated proportions at ambient temperature. Although the order of addition of the various components is not critical if the composition is to be used immediately, the hydrogenation silanization catalyst is usually added last at a temperature below about 30°C to prevent the composition from curing prematurely.

[0218] Furthermore, this multi-component composition can be prepared by combining the components in each portion. This combination can be achieved in a specific apparatus in a batch or continuous process using any technique understood in the art, such as blending or stirring. The specific apparatus is determined by the viscosity of the components and the viscosity of the final composition.

[0219] In some embodiments, when the silicone composition is a multipart silicone composition, the separate portions of the multipart silicone composition can be mixed in a dispensing print nozzle (such as a dual-dispensing print nozzle) before and / or during printing. Alternatively, the separate portions can be combined immediately before printing.

[0220] In another embodiment, the crosslinkable silicone composition X is a crosslinkable silicone composition obtained through a polycondensation reaction, as is well known to those skilled in the art. In this embodiment, composition X comprises:

[0221] - At least one organopolysiloxane G, comprising at least two groups selected from OH groups and hydrolyzable groups,

[0222] - Polycondensation catalyst,

[0223] -Optionally, at least one crosslinking agent H, and

[0224] -Optionally, packing material D as previously disclosed.

[0225] Preferably, the organopolysiloxane G contains at least two groups selected from the following: hydroxyl, alkoxy, alkoxy-alkylene-oxy, amino, amide, acylamino, aminooxy, iminooxy, cetiminoxy, acyloxy, and olefin.

[0226] Advantageously, the polyorganosiloxane G comprises:

[0227] (i) At least two silyloxy units of formula (V):

[0228]

[0229] in:

[0230] -R 1 Same or different indicates a monovalent hydrocarbon group containing 1-30 carbon atoms;

[0231] -Y may be the same or different, each representing a hydrolyzable and condensable group or a hydroxyl group, and preferably selected from hydroxyl, alkoxy, alkoxy-alkylene-oxy, amino, amide, acylamino, aminooxy, iminooxy, ketoiminooxy, acyloxy, iminooxy, ketoiminooxy, and alkenyloxy.

[0232] -g is 0, 1, or 2, h is 1, 2, or 3, the sum of g and h is 1, 2, or 3, and

[0233] (ii) Optionally, one or more silanoxy units of formula (VI):

[0234]

[0235] in:

[0236] -R 2 "Identical" or "different" indicates a monovalent hydrocarbon group comprising 1-30 carbon atoms, optionally substituted with one or more halogen atoms or with amino, ether, ester, epoxy, mercapto, or cyano groups.

[0237] -i can be 0, 1, 2 or 3.

[0238] Examples of hydrolyzable and condensable groups Y of the alkoxy type include groups having 1 to 8 carbon atoms, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, 2-methoxyethoxy, hexoxy, or octoxy.

[0239] As an example of a hydrolyzable and condensable group Y of the alkoxy-alkylene-oxy type, the methoxy-ethylene-oxy group can be mentioned.

[0240] Examples of hydrolyzable and condensable amino groups Y include methylamino, dimethylamino, ethylamino, diethylamino, n-butylamino, sec-butylamino, or cyclohexylamino.

[0241] As an example of a hydrolyzable and condensable amide group Y, the N-methyl-acetamido group can be mentioned.

[0242] As an example of a hydrolyzable and condensable group Y of the acylamino type, the benzoyl-amino group can be mentioned.

[0243] Examples of hydrolyzable and condensable groups Y of the aminooxy type include dimethylaminooxy, diethylaminooxy, dioctylaminooxy, or diphenylaminooxy groups.

[0244] Examples of hydrolyzable and condensable groups Y, particularly of the ketimino type, include groups derived from the following oximes: acetophenone oxime, benzophenone oxime, methyl ethyl ketone oxime, diisopropyl ketone oxime, or methyl isobutyl ketone oxime.

[0245] As an example of a hydrolyzable and condensable group Y of the acyloxy group type, acetoxy can be mentioned.

[0246] As an example of a hydrolyzable and condensable group Y of the olefin type, the 2-propenoxy group can be mentioned.

[0247] The viscosity of organopolysiloxane G is typically between 50 mPa·s and 1,000,000 mPa·s at 25°C.

[0248] Preferably, the organopolysiloxane G has formula (VII):

[0249] Y j R 3 3-j Si-O-(SiR 3 2-O) p -SiR 3 3-j Y j (VII)

[0250] in:

[0251] -Y may be the same or different, each representing a hydrolyzable and condensable group or a hydroxyl group, and preferably selected from hydroxyl, alkoxy, alkoxy-alkylene-oxy, amino, amide, acylamino, aminooxy, iminooxy, ketoiminooxy, acyloxy, and alkenyloxy.

[0252] -R 3 "Identical" or "different" indicates a monovalent hydrocarbon group containing 1-30 carbon atoms, which is optionally substituted with one or more halogen atoms or amino, ether, ester, epoxy, mercapto, or cyano groups.

[0253] -j is 1, 2, or 3, preferably 2 or 3, and when Y is a hydroxyl group, then j = 1.

[0254] -p is an integer equal to or greater than 1, preferably an integer between 1 and 2000.

[0255] In equations (V), (VI), and (VII), R 1 R 2 and R 3 Preferred options are:

[0256] - An alkyl group comprising 1-20 carbon atoms, optionally substituted with one or more aryl or cycloalkyl groups, one or more halogen atoms, or the following groups: amino, ether, ester, epoxy, mercapto, cyano, or (poly)ethylene glycol. Examples include methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, 2-ethylhexyl, octyl, decyl, 3,3,3-trifluoropropyl, 4,4,4-trifluorobutyl, 4,4,4,3,3-pentafluorobutyl;

[0257] -Cycloalkyl and halocycloalkyl groups containing 5-13 carbon atoms, such as cyclopentyl, cyclohexyl, methylcyclohexyl, propylcyclohexyl, 2,3-difluorocyclobutyl and 3,4-difluoro-5-methylcycloheptyl;

[0258] - Mononuclear aryl and haloaryl groups containing 6-13 carbon atoms, such as: phenyl, tolyl, xylyl, chlorophenyl, dichlorophenyl, trichlorophenyl; or

[0259] - Alkenyl groups containing 2-8 carbon atoms, such as vinyl, allyl, and 2-butenyl.

[0260] In a particular embodiment, when G has formula (VII) in which Y has a hydroxyl group, d is therefore preferably 1. In this case, poly(dimethylsiloxane) having a terminal silanol group (also referred to as the "α-ω" position) is preferred.

[0261] Organopolysiloxane G may also be selected from organopolysiloxane resins having at least one hydroxyl or alkoxy group, said group being condensable or hydrolyzable, comprising two distinct siloxy units selected from formulas M, D, T, and Q, wherein:

[0262] -M=(R 0 )3SiO 1 / 2 ,

[0263] -D=(R 0 )2SiO 2 / 2 ,

[0264] -T=R 0 SiO 3 / 2 ,and

[0265] -Q=SiO 4 / 2 ;

[0266] In the above formula, R 0 It represents a monovalent hydrocarbon group containing 1-40 carbon atoms, preferably 1-20 carbon atoms, or a group –OR”’, where R”’ = H or an alkyl group containing 1-40 carbon atoms, preferably 1-20 carbon atoms; provided that the resin contains at least one unit T or Q.

[0267] The resin preferably has a hydroxyl or alkoxy substituent content of 0.1-10% by weight relative to the weight of the resin, and more preferably a hydroxyl or alkoxy substituent content of 0.2-5% by weight relative to the weight of the resin.

[0268] The organopolysiloxane resins typically have approximately 0.001-1.5 OH and / or alkoxy groups per silicon atom. These organopolysiloxane resins are usually prepared by co-hydrolysis or co-condensation of chlorosilanes, such as those of formula (R... 19 )3SiCl、(R 19 )2Si(Cl)2、R 19 Those of Si(Cl)3 or Si(Cl)4, wherein the group R 19 They may be the same or different, and are generally selected from linear or branched C1-C6 alkyl, phenyl, and 3,3,3-trifluoropropyl. For example, R 19 It consists of methyl, ethyl, isopropyl, tert-butyl, and n-hexyl.

[0269] Examples of resins include the following types of silicone-containing resins: T(OH), DT. (OH) DQ (OH) DT (OH) MQ (OH) MDT (OH) MDQ (OH) Or a mixture thereof.

[0270] In this second embodiment, the crosslinkable organosilicon composition via polycondensation may further comprise such a crosslinking agent H. It is preferably an organosilicon compound having more than two hydrolyzable and condensable groups linked to silicon atoms per molecule. Such an agent is well known to those skilled in the art and is commercially available.

[0271] Crosslinking agent H is preferably a silicon compound containing at least three hydrolyzable and condensable groups Y per molecule, wherein agent H has the following formula (VIII):

[0272] R 4 (4-k) SiY k (VIII)

[0273] In this formula:

[0274] -Group R 4 Same or different, indicating C1-C 30 Monovalent hydrocarbon group,

[0275] -Y may be the same as or different from alkoxy, alkoxy-alkylene-oxy, amino, amide, acylamino, aminooxy, iminooxy, ketoiminooxy, acyloxy, and alkenyloxy, and preferably, Y is an alkoxy, acyloxy, alkenyloxy, ketoiminooxy, or oxime group.

[0276] -k = 2, 3 or 4, and preferably k = 3 or 4.

[0277] The examples of group Y are the same as those mentioned above for G when the symbol Y is a hydrolyzable and condensable group.

[0278] Other examples of crosslinking agent H are alkoxysilanes of formula (IX) or partial hydrolysis products of such silanes:

[0279] R 5 I Si(OR 6 ) (4-I) (IX)

[0280] in:

[0281] -R 6 "Same" or "different" indicates an alkyl group containing 1-8 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, 2-ethylhexyl, octyl and decyl, and C3-C6 alkylene oxides.

[0282] -R 5 Same or different, indicating saturated or unsaturated, linear or branched aliphatic hydrocarbon groups, saturated or unsaturated and / or aromatic, monocyclic or polycyclic carbocyclic groups, and

[0283] -I is 0, 1, or 2.

[0284] Among the crosslinking agents H, alkoxysilanes, ketiminosilanes, alkyl silicates, and polyalkyl silicates are preferred, wherein the organic group is an alkyl group having 1-4 carbon atoms.

[0285] Preferably, the following crosslinking agents H are used alone or in combination:

[0286] ○ Polyethyl silicate and polypropyl silicate;

[0287] ○ Alkoxysilanes such as dialkoxysilanes, for example dialkyldialkoxysilanes, trimekoxysilanes, for example alkyltrialkoxysilanes, and tetraalkoxysilanes, and preferably propyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, propyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, 1,2-bis(trimethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethane, tetraisopropoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and those having the following formula: CH2=CHSi(OCH2CH2OCH3)3, Si(OC2H4OCH3)4, and CH3Si(OC2H4OCH3)3.

[0288] Acyloxysilanes, such as the following acetoxysilanes: tetraacetoxysilane, methyltriacetoxysilane, ethyltriacetoxysilane, vinyltriacetoxysilane, propyltriacetoxysilane, butyltriacetoxysilane, phenyltriacetoxysilane, octyltriacetoxysilane, dimethyldiacetoxysilane, phenylmethyldiacetoxysilane, vinylmethyldiacetoxysilane, diphenyldiacetoxysilane, and tetraacetoxysilane.

[0289] ○ Silanes containing alkoxy and acetoxy groups, such as: methyldiacetoxymethoxysilane, methylacetoxydimethoxysilane, vinyldiacetoxymethoxysilane, vinylacetoxydimethoxysilane, methyldiacetoxyethoxysilane, and methylacetoxydiethoxysilane.

[0290] ○Methyltris(methylethyl-ketooxime)silane, 3-cyanopropyltrimethoxysilane, 3-cyanopropyl-triethoxysilane, 3-(glycidoxy)propyltriethoxysilane, vinyltris(methylethyl-ketooxime)silane, tetra(methylethyl-ketooxime)silane.

[0291] Typically, 0.1-60 parts by weight of crosslinking agent H / 100 parts by weight of polyorganosiloxane G is used. Preferably, 0.5-15 parts by weight of crosslinking agent H / 100 parts by weight of polyorganosiloxane G is used.

[0292] The crosslinkable organosilicon composition X (through polycondensation or polyaddition) may further comprise functional additives commonly found in organosilicon compositions. The following family of functional additives may be mentioned:

[0293] - Adhesion promoter;

[0294] - Silicone resin;

[0295] -Thixotropic agent,

[0296] - Coloring agents, and

[0297] - Additives used for heat resistance, oil resistance, and fire resistance, such as metal oxides.

[0298] Polycondensation catalysts can be tin, zinc, iron, zirconium, bismuth, or titanium derivatives, or organic compounds such as amines or guanidines, as disclosed in EP2268743 and EP2222688, for example. Tin monocarboxylate and dicarboxylate tin can be used as tin-derived condensation catalysts, such as tin 2-ethylhexanoate, dibutyltin dilaurate, or dibutyltin diacetate (see Noll's "Chemistry and Technology of Silicone", p. 337, Academic Press, 1968, 2nd edition, or patents EP 147323 or EP 235 049). Other possible metal derivatives include chelates, such as dibutyltin acetylacetonate, sulfonates, alkoxides, etc.

[0299] Adhesion promoters are widely used in silicone compositions. Advantageously, in the method according to the invention, one or more adhesion promoters selected from the following can be used:

[0300] - Alkoxylated organosilanes containing at least one C2-C6 alkenyl group per molecule

[0301] - Organosilicon compounds containing at least one epoxy group,

[0302] - A chelate and / or metal alkoxide of metal M, having the following formula:

[0303] M(OJ) n ,in

[0304] M is selected from: Ti, Zr, Ge, Li, Mn, Fe, Al and Mg or mixtures thereof.

[0305] n = valence of M and J = linear or branched C1-C8 alkyl.

[0306] Preferably, M is selected from the following: Ti, Zr, Ge, Li, or Mn, and more preferably, metallic M is titanium. It can be combined with, for example, an alkoxy group of the butoxy type.

[0307] Silicone resins are branched organopolysiloxanes, which are well-known and commercially available. They have at least two distinct units in their structure, selected from units having the following formula: R3SiO 1 / 2 (M unit), R2SiO 2 / 2 (D unit), RSiO 3 / 2 (T unit) and SiO 4 / 2 (Q-cells), at least one of which is a T or Q-cell.

[0308] The group R can be the same or different and is selected from linear or branched C1-C6 alkyl, hydroxyl, phenyl, 3,3,3-trifluoropropyl. Alkyl groups are, for example, methyl, ethyl, isopropyl, tert-butyl, and n-hexyl.

[0309] Examples of branched organopolysiloxane oligomers or polymers include MQ resins, MDQ resins, TD resins, and MDT resins, in which hydroxyl functional groups may be carried by M, D, and / or T units. As a particularly suitable example of a resin, hydroxylated MDQ resin having 0.2-10% by weight of hydroxyl groups may be mentioned.

[0310] In step 3, the crosslinkable silicone composition X is printed at the temperature T1 defined above. Temperature T1 should be maintained throughout the 3D printing process to ensure a constrained environment.

[0311] Printing is preferably performed layer by layer using a 3D printer. Advantageously, the 3D printer is an extrusion 3D printer.

[0312] Advantageously, in order to keep the temperature T1 constant, the container and 3D printer are placed in a temperature-controlled housing.

[0313] 3D printing is often associated with a number of related technologies used to manufacture physical objects from computer-generated data sources, such as computer-aided design (CAD).

[0314] A 3D printer is defined as a machine for 3D printing, and 3D printing is defined as the manufacture of objects by depositing material using a printhead, nozzle, or other printing technology.

[0315] "Printing" is defined as depositing material (in this case, crosslinkable silicone composition X) using a printhead, nozzle, or other printer technology.

[0316] In this disclosure, "3D or three-dimensional article, object or part" means article, object or part obtained by additive manufacturing or 3D printing as disclosed above.

[0317] Typically, all 3D printing processes share a common starting point: a computer-generated data source or program that describes the object. This computer-generated data source or program can be based on a real or virtual object. For example, a real object can be scanned using a 3D scanner, and the scanned data can be used to create a computer-generated data source or program. Alternatively, the computer-generated data source or program can be designed using computer-aided design software.

[0318] Computer-generated data sources or programs are typically converted into Standard Mosaic Language (STL) file format; however, other file formats may also be used or additionally. This file is usually read into 3D printing software, which takes the file and optional user input information to divide it into hundreds, thousands, or even millions of "slices." The 3D printing software typically outputs machine instructions, which may be in G-code form, which is read by the 3D printer to build each slice. The machine instructions are transmitted to the 3D printer, which then builds the object layer by layer based on the slice information in the form of the machine instructions. The thickness of these slices can vary.

[0319] An extrusion 3D printer is a type of 3D printer in which material is extruded through a nozzle, syringe, or orifice during the manufacturing process. Material extrusion is typically performed by extruded material through a nozzle, syringe, or orifice to print a cross-section of an object, which can be repeated for each subsequent layer. The extruded material bonds to the layers below it during material curing.

[0320] In a preferred embodiment, the method for manufacturing a three-dimensional silicone elastomer article uses an extrusion 3D printer. A crosslinkable silicone composition X is extruded through a nozzle. The nozzle can be heated to aid in the distribution of the addition-crosslinkable silicone composition.

[0321] The silicone composition X dispensed via nozzles can be supplied by a cartridge-like system. This cartridge may include one or more nozzles, each with one or more associated fluid reservoirs. A coaxial dual-cartridge system with a static mixer and only one nozzle can also be used. Pressure will be adapted to the fluid to be dispensed, the associated average nozzle diameter, and the print speed.

[0322] Due to the high shear rate that occurs during nozzle extrusion, the viscosity of the crosslinked silicone composition X is greatly reduced, and therefore fine layers can be printed.

[0323] The ink cartridge pressure can vary from 1 (atm) to 28 bar, preferably 1 to 10 bar, and most preferably 2 to 8 bar. Adapted devices using aluminum ink cartridges will be used to withstand this pressure.

[0324] Before moving in the Z-axis (vertical) plane after completing one layer, the nozzle and / or build platform move in the XY (horizontal) plane to complete the cross-section of the object. The nozzle has a high XYZ movement accuracy of approximately 10 μm. After printing each layer in the X and Y working planes, the nozzle displacement in the Z direction is only far enough to apply the next layer in the X and Y working position. In this way, the object becoming a 3D artifact is built layer by layer from bottom to top.

[0325] The average diameter of the nozzle is related to the thickness of the layer. In one embodiment, the diameter of the layer is 50-2000 μm, preferably 100-800 μm, and most preferably 100-500 μm.

[0326] Advantageously, the printing speed is 1-50 mm / s, preferably 5-30 mm / s, to achieve the best trade-off between good accuracy and manufacturing speed.

[0327] Step 4 of the method of the present invention is optional and depends, among other factors, on the crosslinkable silicone composition X, the temperature T1, and the type of object being printed. As mentioned above, the crosslinkable silicone composition X can be a crosslinkable silicone composition through addition or polycondensation. Those skilled in the art will understand that the kinetics of the crosslinking step are variable, depending on the crosslinkable silicone composition X. As is known to those skilled in the art of 3D printing, crosslinking begins at the start of the printing step, and its kinetics depend on the properties of the composition. The aim is to be able to recycle the formed article while maintaining its shape without deformation. Therefore, in some cases, at the end of step 3, the article may be strong enough to be recycled, and crosslinking may be subsequently completed if necessary. When step 4 is performed, crosslinking may be partial or complete, as long as the recyclable article retains its shape without any deformation.

[0328] Preferably, step 4 is not optional.

[0329] Crosslinking step 4 can be performed by any method known to those skilled in the art, depending on the crosslinkable silicone composition X used. Therefore, this crosslinking step can be performed by waiting at T1 for several minutes or hours until the silicone composition X crosslinks, or by heating at a temperature T2. Temperature T2 depends on the crosslinkable silicone composition X used. This temperature can be determined by those skilled in the art based on their common sense and information about the crosslinkable silicone composition X used (especially information given in the datasheet). Preferably, T2 is 30-90°C, more preferably 40-70°C.

[0330] Step 5 of the method according to the invention enables the liquefaction of the gel formed by composition C, thereby recovering the silicone elastomer article with a small amount of gel in step 6. This step advantageously allows for the recovery of most of composition C, which can then be recycled. Therefore, those skilled in the art can determine the temperature T3 based on composition C. Preferably, T3 is below 15°C, more preferably 0-15°C, and even more preferably 0-10°C.

[0331] Preferably, in the method according to the invention:

[0332] -T1 is 25-50°C, preferably 25-40°C, for example 25-35°C, more preferably 28-32°C, and / or

[0333] -T3 is below 15℃, preferably 0-15℃, and more preferably 0-10℃.

[0334] In certain implementations, step 5 is not included.

[0335] Preferably, if step 5 is not present, step 7 is performed to remove all gel around the silicone elastomer article recovered in step 6.

[0336] Steps 5 and 6 can be reversed. In practice, the silicone elastomer article can be removed and then placed at a temperature T3 below the sol-gel transition temperature of composition C to liquefy any residual gel on the article.

[0337] Advantageously, after steps 5 and 7, composition C is recovered and recycled back to step 1. Composition C can therefore be reused at least 30 times.

[0338] Advantageously, the use of poloxamer according to the invention makes it possible to avoid the use of any solvent other than water in the method of the invention. Therefore, the method of the invention is also preferably characterized by the absence of solvents other than water. This is particularly beneficial for the biological and medical applications of the resulting product.

[0339] As described above, the crosslinkable silicone composition X obtained after step 4 can be partially crosslinked. In those cases, a further crosslinking step is performed at the end of the process after step 6 or 7. This further crosslinking step can be performed by any method known to those skilled in the art, depending on the crosslinkable silicone composition X used. It can be performed, for example, by heating between 100 and 250°C, or under UV radiation of 50-240 W / cm, for a mercury arc lamp, or using an irradiance higher than 15 mW / cm. 2 For LEDs.

[0340] Optionally, the resulting article can be subjected to different post-processing methods. In one embodiment, the method further includes a step of heating the three-dimensional silicone article. Heating can be used to accelerate curing. In another embodiment, the method further includes a step of further irradiating the three-dimensional silicone article. Further irradiation can be used to accelerate curing. In yet another embodiment, the method further includes both the steps of heating and irradiating the three-dimensional silicone article.

[0341] Optionally, post-processing steps can significantly improve the surface quality of printed articles. Sanding is a common method to reduce or remove noticeably different layers on the model. Spraying or coating the surface of elastomer articles with heat- or UV-curable RTV or LSR silicone compositions can be used to obtain a suitable smooth surface appearance.

[0342] Surface treatment can also be done using lasers.

[0343] For medical applications, the final elastomer product can be sterilized, for example by heating in a dry atmosphere or by steam in an autoclave, for example by heating the object at a temperature above 100°C, under gamma rays, sterilized with ethylene oxide, or sterilized with an electron beam.

[0344] This invention also relates to silicone elastomer articles obtained or obtainable by the methods of this invention. These articles can be any article having a simple or complex geometry. They can be, for example, (functional or non-functional) anatomical models such as the heart, limbs, kidneys, prostate, etc., models for surgeons and the educational community, or orthotics or prostheses, or even different categories of implants such as long-term implants: hearing aids, braces, laryngeal implants, etc.

[0345] The present invention also relates to the use of the composition C according to the invention as a constrained environment for manufacturing silicone elastomer articles using a 3D printer.

[0346] The present invention also relates to the use of poly(alkylene oxide glycol), particularly preferred poly(alkylene oxide glycol), especially poly(ethylene oxide glycol) (or polyethylene oxide, PEG) in poloxamer gels to improve self-healing while maintaining and improving the performance of the gel for FRESH 3D printing.

[0347] The present invention also relates to composition C comprising water, at least one poloxamer, and poly(alkylene oxide glycol). The properties and amounts of poloxamer and poly(alkylene oxide glycol) are preferably as described above. Attached Figure Description

[0348] Figure 1 It shows the physiological shape of the mitral valve, eight chordae tendineae and two medial papillary muscles. Detailed Implementation

[0349] The invention will now be disclosed through the following non-limiting embodiments.

[0350] Example 1: General procedure for preparing composition C

[0351] Poloxamer 407 (P407) (Sigma-Aldrich, USA) was dissolved in ice-cold deionized water using the “cold method” described by Schmolka (Schmolka Irving R., Artificial skin I. Preparation and properties of pluronic F-127 gels for treatment of burns. J. Biomed. Mater. Res. 6, 571–582 (2004)). The solution was stored overnight at 4°C to complete dissolution and degassing.

[0352] Before adding P407, poly(ethylene oxide) 400 (PEG400) (M w =400g.mol -1 (Sigma-Aldrich, USA) Diluted in ice-cold ultrapure water.

[0353] Before printing in the support medium, pour the solution into the crystallizer and warm it to ambient temperature until it gels.

[0354] Example 2: Preparation of different compositions C

[0355] The following composition was prepared according to the general procedure described in Example 1:

[0356]

[0357] Table 1

[0358] Example 3: Rheological characterization of composition C

[0359] Rheological measurements were performed using a controlled stress rheometer (DHR-2 rheometer, TA Instruments, USA) with a concentric cylindrical geometry of 14 mm radius and 42 mm height. 15 mL of composition C was introduced into a fixed gap of 3580 μm. The gelation temperature (Tg) was first obtained by frequency scanning (0.1–100 rad / s) after a linear field check. gel The gelation temperature is determined when tanδ = G” / G' = 1. Then, by applying 10 to 10... -5 s -1Static yield stress values ​​were measured by scanning the shear rate and measuring stress at different temperatures (10 to 40 °C, in 5 °C increments) (Table 2). The viscosity of the organosilicon material was measured using a cone-plate geometry with a radius of 40 mm, an angle of 2 °C, and a gap of 50 μm.

[0360]

[0361] Table 2

[0362] These results indicate that polyethylene glycol acts as a plasticizer and enables the reduction of static yield stress.

[0363] CC5 <![CDATA[5.3x10 5 ]]> C1 <![CDATA[3.9x10 5 ]]> C2 <![CDATA[3.9x10 5 ]]> C3 <![CDATA[3.3x10 5 ]]> C4 <![CDATA[5.2x10 5 ]]> C5 <![CDATA[0.7x10 5 ]]>

[0364] Table 3

[0365] Example 4: 3D Printing Process

[0366] A highly complex 3D object was used to challenge the FRESH technique: a physiological shape consisting of the mitral valve, eight chordae tendineae, and two medial papillary muscles. Figure 1 To enable this complex 3D printing, a 6-axis robotic arm was used. (Advanced Solutions Life Sciences, USA) enables the printing of three components (valve, chordae tendineae, and muscle) with different printing path parameters. Once printing is complete, the object is cured (condensation at ambient temperature), removed, and simply cleaned with cold water.

[0367] The printing temperature is fixed at 22±1℃. PDMS (AMSil) has a 10-minute de-sticking time in an atmosphere with 50% relative humidity. TM PDMS (20101, RTV-1alcoxy, Elkem Silicones, France) was used as the printing material loaded into a 30cm³ cartridge (30CC (Nordson EFD, USA)). The cartridge contained a 200μm diameter conical nozzle (Nordson EFD, USA) and was extruded under pneumatic pressure (70PSI). 3D printing was controlled using TSIM software (Advanced Solutions LifeSciences, V1.1.142, USA), with a print speed of 10mm / s for Cartesian printing and 1mm / s for path-based printing. After deposition, the PDMS was cured at 25°C for 48 hours. The support bath was placed at 4°C overnight before recycling the printed object. The mitral valve was then rinsed with cold water. Once dried, specific parts of the object were dimensionally measured using calipers.

[0368] The comparison of compositions CC1, CC2, and CC5 could not achieve the desired results. Figure 1 The selected complex form of FRESH 3D printing. For compositions CC1 and CC2, the gel form cannot suspend the printing material (static yield stress is negligible, composition CC1 does not exhibit a gelation temperature, and CC2 only gels at temperatures above 30°C).

[0369] For composition CC5, poor self-healing performance was confirmed at high static yield stress values ​​(167 Pa at 25°C). This static yield stress enabled the printing of complex objects, but with poor fidelity, mainly due to unhealed cracks that caused the printed material to diffuse beyond its initial deposition path. The overall print fidelity was 56.0 ± 0.76% (see Table 4 below), with low mitral valve surface resolution, unconnected chordae tendineae, and some missing portions of the medial papillary muscle.

[0370]

[0371] Table 4

[0372] Composition C5 was also tested. Figure 1 The selected complex form of FRESH 3D printing was performed. The complete object was suspended within hydrogel C5, and negligible cracks were formed on the gel surface (even using a 30CC syringe, if the diameter is 23mm). Three different printing sequences were used: Cartesian printing of the mitral valve, multi-directional 6-axis printing of eight chordae tendineae, and final Cartesian printing of two medial papillary muscles. These three sequences were considered to introduce greater complexity to the printing process, as multiple objects should be connected within the gel with sufficient cohesion. It is worth noting here that the eight chordae tendineae were printed as single 400μm filaments, located between the other two sequences, yet still cohesive with the other objects. This cohesion is also a remarkable feature of this high-resolution print, as it is a common problem encountered when dealing with FRESH 3D printing. Compared to the product obtained with the CC5 composition, all parts of this product are cohesive, and the surface quality and fidelity to the initial STL file are greatly improved. To document this fidelity, the dimensions of the printed object were measured and compared with the initial STL (Table 5 below).

[0373]

[0374] Table 5

[0375] These components demonstrate that adding PEG to poloxamer solutions can improve self-healing and print fidelity.

Claims

1. A method for manufacturing silicone elastomer articles, comprising the following steps: 1) Provide composition C, comprising water, at least one poloxamer and poly(ethylene oxide glycol), into a container; 2) Place the container containing composition C at the desired temperature T1 to form a gel; 3) Use a 3D printer to print the crosslinkable silicone composition X into the gel obtained in 2) at the required temperature T1; 4) Crosslink the printed composition X partially or completely in the container to obtain a silicone elastomer article; 5) Optionally, the container obtained in step 4) is placed at a temperature T3 below the sol-gel transition temperature of composition C; 6) Recycle silicone elastomer products; 7) Optionally, the obtained silicone elastomer article is washed at a temperature T3 below the sol-gel transition temperature of composition C.

2. The method of claim 1, wherein step 4) comprises partially or completely crosslinking the printed composition X by heating in the container to obtain a silicone elastomer article.

3. The method according to claim 1, wherein the poly(ethylene oxide glycol) has a Mw of 100-6000 g / mol.

4. The method of claim 1, wherein poloxamer is a copolymer composed of poly(propylene oxide) and poly(ethylene oxide) blocks.

5. The method of claim 1, wherein poloxamer is a triblock copolymer consisting of a central poly(propylene oxide) block and two terminal poly(ethylene oxide) blocks.

6. The method of claim 1, wherein the poloxamer comprises 25-90% by weight of poly(ethylene oxide) units based on the total weight of the poloxamer.

7. The method of claim 1, wherein poloxamer is a triblock copolymer consisting of a central poly(propylene oxide) block and two terminal poly(ethylene oxide) blocks, wherein each of the two poly(ethylene oxide) blocks contains 100 ± 10 repeating units, and the poly(propylene oxide) block contains 55 ± 10 repeating units.

8. The method according to claim 1, wherein in composition C, the weight ratio of poly(ethylene oxide glycol) / poloxamer is such that the static yield stress of the gel at a temperature of 20°C-50°C is 0.5-200 Pa.

9. The method of claim 1, wherein in composition C, the weight ratio of poly(ethylene oxide glycol) / poloxam is greater than 0.

5.

10. The method of claim 1, wherein in composition C, the amount of poloxamer is 10-40% by weight, based on the total weight of composition C.

11. The method of claim 1, wherein composition C further comprises one or more compounds selected from: - Alkali; - acid; and - Functionalized silanes.

12. The method according to claim 1, wherein: - T1 is 25-50℃, and / or - T3 is below 15℃.

13. Use of composition C as defined in any one of claims 1-12 as a constrained environment for manufacturing silicone elastomer articles using a 3D printer.

14. Use of poly(ethylene oxide glycol) in poloxamer gels to improve 3D printing fidelity while maintaining and improving the self-healing properties of gels used for FRESH 3D printing.

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