Silicone foam composition

Abstract

The invention relates to a novel silicone foam obtained from a foamable, crosslinkable silicone composition, the invention relates to a composition comprising an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule, an organosilicon-containing compound having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, a hydrosilylation catalyst, at least one porogen as water, hydrogel or aqueous silicone emulsion, and at least one surfactant, at least one chemical blowing agent; and a linear polydimethylsiloxane.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 63 / 393,084, filed on July 28, 2022, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates to the technical field of silicone compositions. More particularly, the present invention relates to new silicone foam compositions having reduced density. Background Art

[0004] Silicone elastomers have attracted great interest because cured silicones have properties such as high elasticity, flexibility at low and high temperatures, high gas permeability, very low glass transition temperature (Tg about -120°C), very good dielectric properties and fire resistance.

[0005] In electronics, silicone elastomers can be used in a wide variety of applications due to their diverse and excellent properties. Cured silicone elastomers are actually used to potting or encapsulate, seal, bond or coat various types of components in harsh environments and high-end precision / sensitive electronic devices such as light-emitting diodes (LEDs), displays, photovoltaic junction boxes in solar cell modules, diodes, semiconductor devices, relays, sensors, automotive stabilizers, automotive electronic control units (ECUs), etc., mainly for electrical insulation, thermal insulation or sound insulation, moisture or dust protection or shock absorption.

[0006] Because silicone foams can offer significant weight savings when compared to non-foamed elastomers, considerable effort has been devoted in recent years to developing methods of introducing porosity into silicone cured materials without adversely affecting their mechanical properties.

[0007] Articles made of silicone foams are known in various fields of application, such as thermal and / or sound insulation, production of flexible joints, use as damping elements, shock absorption, etc. The markets are diverse: construction, transport, electronics, energy production, industrial textiles, performance clothing, household appliances, etc.

[0008] For example, the transportation industry has shown some interest in silicone foams with low density while maintaining excellent mechanical and fire resistance. Articles made of silicone foams can be used as automotive parts such as hood cushions, engine isolators, seats, protective textiles or covers, vibration & noise damping parts, etc. Patent application US2022 / 0275207 discloses silicone foams with a density of less than 0.20 g / cm 3 The silicone foam exhibits good physical, mechanical and fire resistance properties.

[0009] As another example, new energy storage devices consider the use of silicone foams because of their excellent thermal insulation properties, as well as their good moisture resistance and the added advantage of being a lightweight alternative to traditional elastomeric encapsulants and sealants. For example, patent application US2018 / 223070 filed by Elkem Silicones USA Corp. discloses the use of silicone composite foams for thermally insulating secondary battery packs and further minimizing the propagation of thermal runaway.

[0010] In addition to the transport industry and the energy storage sector, silicone foams can be used in various other markets to produce articles. For example, cosmetic puffs, medical absorbents, various filters, various sealing elements such as fillers, gaskets, o-rings, etc. can be mentioned. They can be foamed articles themselves, or they can be composite materials or laminates with metals, organic resins or elastic materials. Other well-known applications of foamed articles are fuser rollers, fuser belts, etc., which fix toners to paper by heat and / or pressure in imaging devices of the electrophotographic type such as copiers, printers, fax machines, etc. In addition, silicone foams can be used in the textile and furniture sectors: insulating coated textiles, footwear and clothing insulation, stuffing, etc. Summary of the invention SUMMARY OF THE INVENTION

[0012] The present invention relates to a silicone foam obtained from a foamable and cross-linkable silicone composition, the foamable and cross-linkable silicone composition comprising:

[0013] - at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule;

[0014] - at least one organosilicon compound B having at least two, preferably at least three, silicon-bonded hydrogen atoms per molecule;

[0015] - at least one hydrosilylation catalyst C;

[0016] - at least one porogen D which is water, a hydrogel or an aqueous silicone emulsion;

[0017] - at least one chemical blowing agent E; and

[0018] - at least one linear polydimethylsiloxane F having a dynamic viscosity at 25° C. of 50 to 100 000 mPa.s.

[0019] The silicone foam defined above can be described as a "double expanded" silicone foam:

[0020] - On the one hand, a porogen D, which is water, a hydrogel or an aqueous silicone emulsion, generates hydrogen bubbles while being incorporated into a polyaddition-crosslinkable silicone composition comprising an organopolysiloxane A having silicon-bonded alkenyl groups, an organosilicon-containing compound B containing silicon-bonded hydrogen atoms, and a hydrosilylation catalyst C, and

[0021] - Chemical blowing agents E, on the other hand, release gas, typically carbon dioxide, by decomposition.

[0022] The present inventors have discovered that the resulting double-foamed silicone foam exhibits a low density and a foam cell structure that is significantly more uniform and stable than using only one blowing agent or the other, while also maintaining a soft, shock-resistant feel.

[0023] Detailed description of the invention

[0024] All viscosities considered in this description correspond to dynamic viscosity quantities, measured in a manner known per se at 25° C. at a shear rate gradient low enough to make the viscosity measured with a Brookfield-type machine independent of the rate gradient.

[0025] Unless specifically stated otherwise, the contents expressed in % or ppm are by weight.

[0026] The foamable and crosslinkable silicone composition according to the present invention comprises at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule. Preferably, the organopolysiloxane A has at least two silicon-bonded C2-C6 alkenyl groups per molecule. It may be composed of the following units: at least two siloxy units of the following formula: Y a R 1 b SiO (4-a-b) / 2

[0027] in:

[0028] - Y represents a C2-C6 alkenyl group, preferably a vinyl group,

[0029] -R 1 is a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably selected from an alkyl group having 1 to 8 carbon atoms such as methyl, ethyl or propyl, a cycloalkyl group having 3 to 8 carbon atoms and an aryl group having 6 to 12 carbon atoms,

[0030] - a=1 or 2, b=0, 1 or 2 and the sum of a+b=2 or 3,

[0031] and optionally, units of the formula: R 1 c SiO (4-c) / 2

[0032] Where R 1 has the same meaning as above and c=0, 1, 2 or 3.

[0033] Preferably, the dynamic viscosity of organopolysiloxane A at 25° C. may be 100 to 120,000 mPa.s, preferably 100 to 80,000 mPa.s, more preferably 1,000 to 50,000 mPa.s, even more preferably 5,000 to 20,000 mPa.s. The organopolysiloxane A may preferably be referred to as organopolysiloxane oil.

[0034] The organopolysiloxane A may be a linear organopolysiloxane, a cyclic organopolysiloxane or a branched organopolysiloxane (resin). The foamable and crosslinkable silicone composition according to the invention may contain a mixture of different organopolysiloxanes A.

[0035] According to one embodiment, the organopolysiloxane A may be a linear organopolysiloxane. The linear organopolysiloxane exhibits a structure consisting essentially of D or D Vi Siloxy unit and terminal M or M Vi The linear structure formed by the siloxy unit, where D, D Vi , M and M Vi The definition is as follows: D:R 1 2SiO 2 / 2 Siloxy unit, D Vi :Selected from Y2SiO 2 / 2 or YR 1 SiO 2 / 2 Siloxyl unit of siloxyl unit, M:R 1 3SiO 1 / 2 Siloxy unit, M Vi :Selected from YR 1 2SiO 1 / 2 and Y2R 1 SiO 1 / 2 Siloxy units; symbols Y and R 1 As described above.

[0036] As the end "M or M Vi As examples of " " units, there may be mentioned trimethylsiloxy, dimethylphenylsiloxy, dimethylvinylsiloxy or dimethylhexenylsiloxy.

[0037] As "D or D Vi As examples of " " units, there may be mentioned dimethylsiloxy, methylphenylsiloxy, methylvinylsiloxy, methylbutenylsiloxy, methylhexenylsiloxy, methyldecenylsiloxy or methyldecadienylsiloxy.

[0038] Examples of linear or cyclic organopolysiloxanes which may be the organopolysiloxane A according to the invention are:

[0039] - poly(dimethylsiloxane) containing dimethylvinylsilyl end groups;

[0040] - poly(dimethylsiloxane-co-methylphenylsiloxane) containing dimethylvinylsilyl end groups;

[0041] - poly(dimethylsiloxane-co-methylvinylsiloxane) containing dimethylvinylsilyl end groups;

[0042] - poly(dimethylsiloxane-co-methylvinylsiloxane) containing trimethylsilyl termini; and

[0043] - Cyclic poly(methylvinylsiloxane).

[0044] Preferably, the organopolysiloxane A has a weight content of alkenyl units of 0.001% to 30%, preferably 0.01% to 10%, preferably 0.02% to 5%.

[0045] According to a preferred embodiment, the organopolysiloxane A comprises terminal dimethylvinylsilyl units, and even more preferably, the organopolysiloxane A is a poly(dimethylsiloxane) comprising terminal dimethylvinylsilyl groups. The number of dimethylsiloxane units may be 5-1000, preferably 100-600.

[0046] According to another embodiment, the organopolysiloxane A may be a 2-6 Branched organopolysiloxane (i.e. resin) of alkenyl units. It is preferably selected from the organosilicon resin of the following formula:

[0047] -M Vi Q, in which the alkenyl group bonded to the silicon atom is carried by the M group,

[0048] -MM Vi Q, in which the alkenyl group bonded to the silicon atom is carried by a portion of the M unit,

[0049] -MD Vi Q, in which the alkenyl group bonded to the silicon atom is carried by the D group,

[0050] -MDD Vi Q, wherein the alkenyl group bonded to the silicon atom is carried by a portion of the D group,

[0051] -MM Vi TQ, in which the alkenyl group bonded to the silicon atom is carried by a portion of the M unit,

[0052] -MM Vi DD Vi Q, in which the hydrogen atoms bonded to the silicon atoms are carried by a portion of the M and D units,

[0053] - and mixtures thereof,

[0054] Among them, M Vi , D and D Vi As defined above, T: Formula R 1 SiO 3 / 2 Siloxy units, and Q: formula SiO 4 / 2 The siloxy units, where R 1 Has the same meaning as above.

[0055] According to a preferred embodiment, the foamable crosslinkable silicone composition according to the present invention comprises a mixture of at least one linear organopolysiloxane as defined above and at least one branched organopolysiloxane (i.e., resin) as defined above. For example, the foamable crosslinkable silicone composition according to the present invention may comprise a mixture of a linear poly(dimethylsiloxane) containing dimethylvinylsilyl end groups and a branched organopolysiloxane of formula M Vi Q.MM Vi Q.MD Vi Q. MDD Vi Q.MM Vi TQ or MM Vi DD Vi Q, preferably M Vi Q.MM Vi Q.MD Vi Q or MDD Vi A mixture of silicone resins of Q. The amount of linear poly(dimethylsiloxane) in the foamable and crosslinkable silicone composition according to the present invention may be 0.8%-94% by weight, preferably 2.5%-45% by weight, and more preferably 3.5%-25% by weight of the total composition. The amount of silicone resin in the foamable and crosslinkable silicone composition according to the present invention may be 0%-10% by weight, preferably 0.01%-5% by weight, and more preferably 0.05%-2% by weight of the total composition.

[0056] The foamable and crosslinkable silicone composition according to the present invention further comprises at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule. The organic silicon-containing compound B is preferably an organohydrogenpolysiloxane compound containing at least two and preferably at least three hydrosilyl functional groups (or Si-H units) per molecule.

[0057] The organic silicon-containing compound B may advantageously be an organopolysiloxane comprising at least two, preferably at least three, siloxy units of the formula: d R 2 e SiO (4-d-e) / 2 ,

[0058] in:

[0059] - Same or different R 2 represents a monovalent group having 1 to 12 carbon atoms,

[0060] - d = 1 or 2, e = 0, 1 or 2 and d + e = 1, 2 or 3;

[0061] and optionally, other units of the formula: R 2 f SiO (4-f) / 2 ,

[0062] Where R 2 has the same meaning as above, and f=0, 1, 2 or 3.

[0063] It should be understood that in the above formula, if there are multiple R 2 groups, they may be the same or different from each other. 2 R may represent a monovalent group selected from an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms and an aryl group having 6 to 12 carbon atoms which is optionally substituted by at least one halogen atom such as chlorine or fluorine. 2 can be advantageously selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl and phenyl, and most preferably, R 2 It's methyl.

[0064] The sign d is preferably equal to 1.

[0065] The organic silicon-containing compound B may have a linear, branched or cyclic structure. The degree of polymerization is preferably greater than or equal to 2. Typically, it is less than 5,000.

[0066] When it comes to linear polymers, they are essentially selected from the group consisting of polymers having the formula D:R 2 2SiO 2 / 2 or D':R 2 HSiO 2 / 2 The siloxy units of the units and the units selected from the group consisting of the units of the formula M:R 2 3SiO 1 / 2 or M':R 2 2HSiO 1 / 2 The terminal siloxy unit of the unit is formed, wherein R 2 Has the same meaning as above.

[0067] Preferably, the viscosity of the organic silicon-containing compound B is from 1 mPa.s to 5,000 mPa.s, more preferably from 1 mPa.s to 2,000 mPa.s, and still more preferably from 5 mPa.s to 1,000 mPa.s.

[0068] Examples of organohydrogenpolysiloxanes that may be the organosilicon-containing compound B according to the invention comprising at least two silicon-bonded hydrogen atoms are:

[0069] - poly(dimethylsiloxane) containing hydrodimethylsilyl termini;

[0070] - poly(dimethylsiloxane-co-methylhydrogensiloxane) containing trimethylsilyl termini;

[0071] - poly(dimethylsiloxane-co-methylhydrogensiloxane) containing hydrodimethylsilyl termini;

[0072] - poly(methylhydrogenosiloxane) containing trimethylsilyl termini; and

[0073] - Cyclic poly(methylhydrogensiloxane).

[0074] When the organic silicon-containing compound B has a branched structure, it is preferably selected from the organic silicone resins of the following formula:

[0075] - M'Q, in which the hydrogen atom bonded to the silicon atom is carried by the M group,

[0076] - MM'Q, in which the hydrogen atoms bonded to the silicon atoms are carried by a part of the M unit,

[0077] - MD'Q, in which the hydrogen atom bonded to the silicon atom is carried by the D group,

[0078] - MDD'Q, in which the hydrogen atom bonded to the silicon atom is carried by a part of the D group,

[0079] - MM'TQ, in which the hydrogen atoms bonded to the silicon atoms are carried by a part of the M unit,

[0080] - MM'DD'Q, in which the hydrogen atoms bonded to the silicon atoms are carried by a portion of the M and D units,

[0081] - and mixtures thereof,

[0082] wherein M, M', D and D' are as defined above, T: Formula R 2 SiO 3 / 2 Siloxy units and Q: formula SiO 4 / 2 The siloxy units, where R 2Has the same meaning as above.

[0083] Preferably, the weight content of hydrosilyl Si—H functional groups in the organic silicon-containing compound B is 0.2% to 91%, more preferably 3% to 80%, and more preferably 15% to 70%.

[0084] Advantageously, the molar ratio of hydrosilyl SiH functional groups of the organic silicon-containing compound B to olefin functional groups of the compound A is from 1 to 50, preferably from 2 to 30, more preferably from 3 to 20.

[0085] According to a preferred embodiment, the foamable crosslinkable silicone composition according to the invention comprises a mixture of at least one organic silicon-containing compound B1 having at least three silicon-bonded hydrogen atoms per molecule and at least one organic silicon-containing compound B2 having two silicon-bonded hydrogen atoms per molecule. The organic silicon-containing compound B2 preferably contains terminal dimethylhydrogensilyl units, and even more preferably, the organic silicon-containing compound B2 is a poly(dimethylsiloxane) containing terminal dimethylhydrogensilyl groups. The number of dimethylsiloxane units in the organic silicon-containing compound B2 may be from 1 to 200, preferably from 1 to 150, more preferably from 3 to 120. Such an organic silicon-containing compound B2 may be described as a "chain extender" due to its presumed effect of increasing the mesh size of the network when it is crosslinked. In addition, such an organic silicon-containing compound B1 having three or more silicon-bonded hydrogen atoms per molecule may be described as a "crosslinker". Preferably, the organic silicon-containing compound B1 is a poly(dimethylsiloxane-co-methylhydrogensiloxane) containing trimethylsilyl terminal groups and / or hydrodimethylsilyl terminal groups.

[0086] The hydrosilylation catalyst C may be chosen in particular from compounds of platinum and rhodium, but may also be chosen from silicon compounds, such as those described in patent applications WO2015 / 004396 and WO2015 / 004397; germanium compounds, such as those described in patent application WO2016 / 075414; or complexes of nickel, cobalt or iron, such as those described in patent applications WO2016 / 071651, WO2016 / 071652 and WO2016 / 071654. Catalyst C is preferably a compound derived from at least one metal belonging to the platinum group. These catalysts are well known. Use may in particular be made of complexes of platinum with organic products as described in US Pat. Nos. 3,159,601, 3,159,602 and 3,220,972 and EP 0057459, EP 0188978 and EP 0190530, or of complexes of platinum with vinylated organosiloxanes as described in US Pat. Nos. 3,419,593, 3,715,334, 3,377,432 and 3,814,730.

[0087] Preferably, catalyst C is a compound derived from platinum. Preferably, catalyst C is a Karstedt platinum catalyst.

[0088] The foamable and cross-linkable silicone composition according to the present invention comprises water, hydrogel or aqueous silicone emulsion as porogen D. Water can be directly added to the foamable and cross-linkable silicone composition. Advantageously, water can be introduced in the form of an aqueous silicone emulsion, such as an oil-in-water silicone direct emulsion or an oil-in-water silicone inverse emulsion, which comprises a silicone oil continuous phase, an aqueous phase and a stabilizer.

[0089] According to one embodiment, water is introduced via an emulsion of silicone oil in water having a water content of about 60% by weight. When water is introduced into the foamable crosslinkable silicone composition via an emulsion, the dispersion of water in the foamable crosslinkable silicone composition and its storage stability are improved.

[0090] According to one embodiment, an emulsifier may be added with water or with an aqueous silicone emulsion. The emulsifier may be selected by a person skilled in the art from typical emulsifiers. It may be an anionic, cationic, amphoteric or nonionic emulsifier. Of these, nonionic surfactants are most preferred because they may have the least effect on the hydrosilylation reaction. The emulsifier may be added in an amount such that the weight ratio of emulsifier to water may be from 1:5 to 5:1, preferably from 2:1 to 1:2.

[0091] A portion of the hydrosilyl functional groups of the organic silicon-containing compound B will react with the water provided by the porogen D and form gaseous hydrogen, making good foaming of the composition possible.

[0092] The foamable and cross-linkable silicone composition according to the present invention comprises at least one chemical blowing agent E. Preferably, the chemical blowing agent E is at least one bicarbonate salt (also commonly referred to as "bicarbonate salt"). More preferably, the chemical blowing agent E is selected from ammonium bicarbonate (NH4)HCO3, sodium bicarbonate NaHCO3, calcium bicarbonate Ca(HCO3)2 and mixtures thereof. Even more preferably, the chemical blowing agent E is ammonium bicarbonate.

[0093] The chemical blowing agent E may have a median particle size (D50) of ≤50 μm, even more preferably ≤10 μm. According to a preferred embodiment, the particles of the chemical blowing agent E may be ground and sieved before use.

[0094] For ease of application and production, the chemical blowing agent E may be pre-dispersed in the organopolysiloxane A, for example at a level of 30% to 60% by weight, and eventually incorporated with any additives that may help stabilize the resulting composition for shelf life.

[0095] The foamable and crosslinkable silicone composition according to the present invention comprises at least one linear polydimethylsiloxane F having a dynamic viscosity at 25° C. of 50 to 100,000 mPa.s, preferably 50 to 70,000 mPa.s, more preferably 100 to 20,000 mPa.s, more preferably 200 to 5,000 mPa.s, even more preferably 1,000 to 2,000 mPa.s.

[0096] According to a first embodiment of the invention, the linear polydimethylsiloxane F has the following formula: (CH3)3SiO(SiO(CH3)2) n Si(CH3)3 (I)

[0097] wherein n is an integer of 50-900, preferably 50-700.

[0098] According to a second embodiment of the present invention, the linear polydimethylsiloxane F has the following formula: (CH3)3SiO(SiO(CH3)2) n Si(CH3)2(Y) (II)

[0099] Where Y is C 2-6 The alkenyl group is preferably vinyl, and n is an integer from 50 to 900, preferably from 50 to 700. The compound has exactly one silicon-bonded alkenyl group per molecule.

[0100] Preferably, the linear polydimethylsiloxane F according to the invention is a mixture of linear polydimethylsiloxanes (I) and (II). The weight ratio of (I): (II) may be from 100:0 to 0:100, or from 90:10 to 10:90, or from 80:20 to 20:80, or from 70:30 to 30:70. The foamable and crosslinkable silicone composition according to the invention may be free of or substantially free of linear polydimethylsiloxane (II). The linear polydimethylsiloxane F according to the invention is one or more linear polydimethylsiloxanes (I) as defined above.

[0101] The foamable, cross-linkable silicone composition according to the invention may optionally contain additives. Examples of suitable additives include: elastic additives, reinforcing fillers, thermally or electrically conductive fillers, nanoparticles, silicone resins, pigments, antimicrobial agents, UV stabilizers, dyes, pigments, fragrances, flavoring agents, essential oils, flame retardant additives, thermal stabilizers, rheology modifiers, viscosity modifiers, thickeners, adhesion promoters, biocides, preservatives, enzymes, peptides, surfactants, active diluents, active pharmaceutical ingredients, excipients or cosmetic ingredients. The content of additives is generally less than 5% by weight, preferably less than 2.5% by weight, more preferably less than 1% by weight, relative to the total weight of the foamable, cross-linkable silicone composition. Suitable additive(s) may be selected by a person skilled in the art according to the intended application and the general knowledge in the art.

[0102] According to one embodiment, the foamable crosslinkable silicone composition according to the present invention may optionally contain at least one filler, preferably a reinforcing filler, which generally improves the mechanical strength of the cured silicone elastomer article. The filler may be precipitated silica, fumed (or pyrolyzed) deposited silica, colloidal silica and mixtures thereof. The specific surface area of ​​these active reinforcing fillers should be at least 10 m 2 / g, and preferably 50m 2 / g to 400m 2 In a preferred embodiment, the silica reinforcing filler has a specific surface area of ​​at least 10 m2 as determined by the BET method. 2 / g and preferably 50m 2 / g to 400m 2 / g of fumed silica. The fumed silica can be used as it is in an untreated form, but is preferably subjected to a hydrophobic surface treatment. The amount of silica reinforcing filler in the foamable and crosslinkable silicone composition according to the present invention can be 0%-10% by weight, preferably 0.01%-5% by weight, and more preferably 0.05%-2% by weight of the total composition.

[0103] According to one embodiment, the foamable and cross-linkable silicone composition according to the present invention may optionally contain hollow microspheres. As examples of suitable hollow microspheres, hollow glass microspheres or hollow ceramic microspheres may be cited.

[0104] Hollow glass microspheres are sometimes called "hollow glass beads" or "hollow glass bubbles". They are small hollow spheres of hardened silica (glass) whose size and density can vary depending on the grade. They have a shell that is thick enough to maintain structural rigidity. Due to their hollow nature, they are very lightweight and the density varies with size and wall thickness. In bulk, they appear as a white powder. The main differences between the grades are their size, strength and density, where the strength of the microspheres is expressed as their average isostatic crushing strength.

[0105] According to one embodiment, the hollow glass beads are hollow borosilicate glass microspheres.

[0106] According to one embodiment, the hollow glass microspheres have a true density of 0.10 g / cm 3 (g / cm3) to 0.75g / cm 3 .

[0107] The term "true density" is the quotient obtained by dividing the mass of the hollow glass microsphere sample by the true volume of that mass of glass bubbles (measured by a gas densimeter). The "true volume" is the aggregated total volume of the glass bubbles, not the bulk volume.

[0108] According to a preferred embodiment, the hollow glass microspheres are selected from:

[0109] 1. 3M™ Glass Bubbles Floated Series (A16 / 500, G18, A20 / 1000, H20 / 1000, D32 / 4500 and H50 / 10,000EPX glass bubble products) and 3M™ Glass Bubbles K, S, iM and XLD Series (such as, but not limited to, K1, K11, K15, S15, S22, K20, K20HS, K25, S32, S32LD, S35, XLD3000, S28HS, S35, K37, S38, S38HS, S38XHS, S32HS, K46, K42HS, S42XHS, S60, S60HS, iM16K, iM30K glass bubble products) are sold by 3M Company. The glass bubbles exhibit various crushing strengths ranging from 1.72 MPa (250 psi) to 186.15 MPa (27,000 psi), at which ten percent of the volume of the first plurality of glass bubbles is broken. Other glass bubbles sold by 3M may also be used, such as 3M™ Glass Bubbles-HGS Series and 3M™ Glass Bubbles with Surface Treatment.

[0110] 2. Hollow glass microspheres sold under the trade name SPHERICEL® (such as the following products: 110P8, 60P18, 34P30 and 25P45) or under the trade name Q-Cel® Lightweight (such as the following products: 6014, 6019, 7019, 6019S, 5020, 5020FPS, 7023, 7028, 2058, 6036, 7037, 7040S, 6042S, 6048 and 5070S), sold by Potters Industries Inc.

[0111] Suitable hollow glass microspheres are unsurface treated or surface treated. Surface treated hollow glass microspheres may typically be hydrophobic. The surface treatment agent may be, for example, a silane coupling agent, such as aminopropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane, γ-(methacryloyloxy)propyl trimethoxysilane (also known as silane coupling agent KH-570) and sodium methyl silicate.

[0112] Hollow ceramic microspheres, also known as cenospheres, are lightweight, inert hollow spheres filled with inert air or gas, typically produced as a byproduct of coal combustion in thermal power plants. They are made primarily of silica and alumina. The color of cenospheres varies from gray to almost white, and their density is about 0.4 g / cm 3 -0.8g / cm 3 . It flows like a liquid and has a powdery appearance. Suitable hollow microspheres are unsurface treated or surface treated with a silane-based coupling agent, such as one or more of the following: 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminopropylmethyldimethoxysilane or 3-aminopropylmethyldiethoxysilane.

[0113] Commercially available examples of hollow ceramic microspheres are produced by 3M TM Commercially available Z-Light™ Spheres Microspheres (such as the following products: 3M TM Z-Light™ Spheres G-3125, G-3150 and G-3500).

[0114] According to one embodiment, the foamable and cross-linkable silicone composition according to the invention comprises (by weight, relative to the total weight of the composition):

[0115] - a partial mixture of 1.99% to 98.99% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C and at least one porogen D, the porogen D being water, a hydrogel or an aqueous silicone emulsion;

[0116] - 0.01% to 2% of at least one chemical blowing agent E; and

[0117] - 1% to 98% of at least one linear polydimethylsiloxane F having a dynamic viscosity at 25°C of 50 to 100000 mPa.s.

[0118] According to another embodiment, the foamable and cross-linkable silicone composition according to the invention comprises (by weight, relative to the total weight of the composition):

[0119] - 4.95% to 49.95% of a partial mixture of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C and at least one porogen D, the porogen D being water, a hydrogel or an aqueous silicone emulsion;

[0120] - 0.05% to 1.5% of at least one chemical blowing agent E; and

[0121] - 50% to 95% of at least one linear polydimethylsiloxane F having a dynamic viscosity at 25°C of 50 to 100000 mPa.s.

[0122] According to another embodiment, the foamable and cross-linkable silicone composition according to the invention comprises (by weight, relative to the total weight of the composition):

[0123] - 6.9% to 24.9% of a partial mixture of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C and at least one porogen D, the porogen D being water, a hydrogel or an aqueous silicone emulsion;

[0124] - 0.1% to 1.0% of at least one chemical blowing agent E; and

[0125] - 75% to 93% of at least one linear polydimethylsiloxane F having a dynamic viscosity at 25°C of 50 to 100000 mPa.s.

[0126] Within the above-mentioned embodiment, a partial mixture of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C, and at least one porogen D which is water, a hydrogel, or an aqueous silicone emulsion may have the following composition (by weight relative to the total weight of the partial mixture):

[0127] - 40% to 95% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule;

[0128] - 1% to 20% of at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule;

[0129] - 2 to 400 ppm of at least one platinum hydrosilylation catalyst C, calculated on the weight of platinum metal;

[0130] - 0.3% to 2.5% of at least one porogen D, wherein the porogen D is water, hydrogel or aqueous silicone emulsion.

[0131] More preferably, the partial mixture may have the following composition (by weight, relative to the total weight of the partial mixture):

[0132] - 50% to 90% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule;

[0133] - 3% to 15% of at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule;

[0134] - 5 ppm to 200 ppm of at least one platinum hydrosilylation catalyst C, calculated on the weight of platinum metal;

[0135] - 0.5% to 1.5% of at least one porogen D, wherein the porogen D is water, hydrogel or aqueous silicone emulsion.

[0136] The foamable crosslinkable silicone composition according to the invention may be a two-component system, wherein the two-component system is provided as two separate parts P1 and P2 intended to be mixed to form the foamable crosslinkable silicone composition. One of the parts P1 or P2 comprises at least one hydrosilylation catalyst C and does not comprise at least one organic silicon-containing compound B.

[0137] Another object of the present invention relates to a method for preparing an article made of the silicone foam disclosed above.

[0138] According to a first embodiment, the present invention is directed to a process for preparing an article made of silicone foam, comprising the following steps:

[0139] 1a) combining the components of the foamable, cross-linkable silicone composition according to the invention and as defined above to provide a precursor for a silicone foam,

[0140] 1b) filling the silicone foam precursor into a mold, and

[0141] 1c) foaming and crosslinking the silicone foam precursor.

[0142] According to said embodiment, step 1b) can preferably be carried out in a mold so that the silicone foam can have a specific desired geometry.

[0143] According to a second embodiment, the present invention is directed to a process for preparing an article comprising a substrate coated with a silicone foam, comprising the following steps:

[0144] 2a) combining the components of the foamable, cross-linkable silicone composition according to the invention and as defined above to provide a precursor for a silicone foam,

[0145] 2b) applying the precursor of the silicone foam to a substrate, which is preferably a woven, nonwoven or composite textile,

[0146] 2c) foaming and crosslinking the silicone foam precursor.

[0147] Step 1c) and step 2c) of the method according to the present invention (i.e. foaming and crosslinking of the precursor to form a silicone foam) can be carried out by heating at a temperature range of 50°C-200°C, preferably 100°C-170°C. The temperature of step c) can be adjusted according to the degradation temperature of the chemical blowing agent E. For example, for ammonium bicarbonate, the degradation temperature is about 60°C. The temperature of step 1c) and step 2c) can preferably be set to above 60°C so that both foaming and crosslinking can be carried out substantially simultaneously. Alternatively, step 1c) and step 2c) can be started at room temperature, and the temperature can be increased thereafter in order to control the foaming by the chemical blowing agent E and the crosslinking, respectively.

[0148] Another object of the present invention is to provide a new method for additive manufacturing of 3D shaped articles made of said silicone foam. Such a method also enables the manufacture of complex shaped objects made of such material.

[0149] An object of the present invention relates to a method for additively manufacturing a 3D-shaped article made of silicone foam, comprising the following steps:

[0150] 3a) printing a portion of the foamable, cross-linkable silicone composition as defined above using a 3D printer to form a deposit in a support material SM, the support material SM being a gel or microgel suitable for 3D-gel printing of silicone foams, the deposit being achieved by means of a device having at least one delivery unit positionable in the x-, y- and z-directions,

[0151] 3b) partially or completely foaming and crosslinking the printed foamable and cross-linkable silicone composition to obtain a silicone foam deposit within the support material SM,

[0152] 3c) Optionally, repeating steps a) and b) a number of times until the desired 3D-shape is obtained,

[0153] 3d) removing the support material SM mechanically or via dissolution in a solvent, and

[0154] 3e) Recycling of 3D-shaped articles made from silicone foam.

[0155] According to a specific embodiment, step 3b) can be carried out by heating in a temperature range of 50°C-200°C, preferably 100°C-170°C. The temperature of step 3b) can be adjusted according to the degradation temperature of the chemical blowing agent E. For example, for ammonium bicarbonate, the degradation temperature is about 60°C. The temperature of step 3b) can preferably be set to above 60°C so that both foaming and crosslinking can be carried out substantially simultaneously. Alternatively, step 3b) can be started at room temperature, and the temperature can be increased thereafter in order to control the foaming by the chemical blowing agent E and the crosslinking, respectively. This specific embodiment can advantageously provide a silicone foam having anisotropic properties.

[0156] Printing is preferably performed layer by layer using a 3D printer which may be selected from an extrusion 3D printer or a material jetting 3D printer. 3D printing is often associated with a number of related technologies for making physical objects from computer-generated (such as computer-aided design (CAD)) data sources. A "3D printer" is defined as a machine for 3D printing, and "3D printing" is defined as the production of an object by depositing material using a print head, nozzle or another printer technology".

[0157] In a preferred embodiment, the method for manufacturing an article made of silicone foam according to the present invention uses an extrusion 3D printer. The foamable cross-linkable silicone composition is extruded through a nozzle. The nozzle can be heated to help distribute the addition cross-linkable silicone composition. The foamable cross-linkable silicone composition to be distributed through the nozzle can be supplied by a cartridge-like system. A coaxial cartridge system with a static mixer and only one nozzle can also be used. The pressure will be adapted to the fluid to be distributed, the relevant nozzle average diameter and the printing speed. Due to the high shear rate that occurs during the nozzle extrusion process, the viscosity of the foamable cross-linkable silicone composition is greatly reduced, thereby allowing the printing of fine layers. The cartridge pressure can vary from 1 bar (i.e. atmospheric pressure) to 28 bar, preferably from 1 bar to 10 bar, and most preferably from 2 bar to 8 bar. An adapted device using an aluminum cartridge will be used to resist this pressure. Before moving in the z-axis (vertical) plane once a layer is completed, the nozzle and / or the building platform moves in the xy (horizontal plane) to complete the cross section of the object. The nozzle has a high xyz-movement accuracy of about 10 pm. After printing each layer on the x-, y-working plane, the nozzle is displaced in the z-direction only far enough to apply the next layer in the x-, y-working position. In this way, the 3D article is built one layer at a time from bottom to top. The average diameter of the nozzle is related to the thickness of the layer. In one embodiment, the diameter of the layer is 50 pm-2000 pm, preferably 100 pm-800 pm, most preferably 100 pm-500 pm. Advantageously, the printing speed is 1 mm / s to 50 mm / s, preferably 5 mm / s to 30 mm / s, to obtain the best compromise between good accuracy and manufacturing speed.

[0158] The support material SM is a gel or microgel suitable for 3D-gel printing of silicone foam. The gel or microgel provides constant support for the liquid material during 3D-printing. This allows more complex objects to be printed without the need for additional supports, and at a faster speed. The support material SM can be selected by a person skilled in the art from disclosed materials, such as those disclosed in the following documents: International Patent Applications WO 2019 / 215190 A1 and WO 2020 / 127882 A1, or US Patent Applications US 2015 / 0028523 A1, US 2018 / 0036953 A1, and US 2018 / 0057682 A1. Further details can also be found in the scientific publication by Arthur Colly, Christophe Marquette and Edwin-Joffrey Courtial: “Poloxamer / Poly(ethylene glycol) Self-Healing Hydrogel for High-Precision Freeform Reversible Embedding of Suspended Hydrogel” (Langmuir 2021, 37, 14, 4154-4162).

[0159] According to one embodiment of the claimed method, the support material SM can be provided as a matrix, for example in a container, and placed at a desired temperature. According to another embodiment, the support material SM can be delivered at specific locations simultaneously with the foamable, cross-linkable silicone composition or at staggered intervals by means of a device having at least one delivery unit positionable in the x-, y- and z-directions.

[0160] The present invention further relates to the use of the silicone foam defined in the present invention in the electronics field, the transportation field, the aerospace field, the energy production field and the energy storage field, the textile and furniture field, and the construction field. Examples of use are as follows:

[0161] - In the electronics market: potting or encapsulating, sealing, bonding or coating various types of components, as well as high-end precision / sensitive electronic devices such as light emitting diodes (LEDs), displays, photovoltaic junction boxes in solar cell modules, diodes, semiconductor devices, relays, sensors, automotive stabilizers, automotive electronic control units (ECUs),

[0162] - In the transportation sector: automotive, marine or aerospace components, such as hood cushions, engine isolators, seats, vibration & noise damping elements,

[0163] - In the aerospace field: aerospace thermal insulation,

[0164] - In the field of energy production and energy storage: high-voltage electrical insulation, insulation of secondary battery packs, insulation of stationary energy storage devices, and insulation of charging stations, in solar photovoltaic cells and modules, windmills, hydropower modules,

[0165] - In the textile and furniture sector: insulation coated and laminated textiles, artificial leather, footwear and clothing insulation, padding,

[0166] - In the construction sector: electrical protection of buildings,

[0167] - In other fields: cosmetic puffs, medical absorbent materials, various filters, various sealing elements such as packing, gaskets, o-rings, flexible joints, damping elements, fixing rollers, fixing belts, etc., which fix toners to paper by heat and / or pressure in electrophotographic type imaging devices such as copiers, printers, fax machines.

[0168] Depending on the application, the silicone foam can be used to make the foamed article itself, or can be used to make a composite material or laminate with metal, organic resin or elastic material. For example, the composite article can comprise a shell and a filler, wherein the filler consists of or comprises the silicone foam according to the invention. DETAILED DESCRIPTION

[0169] Various embodiments of the present invention may be better understood by reference to the following examples, which are provided by way of illustration.The present invention is not limited to the examples given herein.

[0170] Example

[0171] raw material:

[0172] Organopolysiloxane A1 = a mixture of several polydimethylsiloxane oils having dimethylvinylsilyl terminal units, with viscosities varying from about 4,000 mPa to about 100,000 mPa.s at 25°C, and an average viscosity of about 10,000 mPa.s at 25°C.

[0173] Organopolysiloxane A2 = MD Vi Q branched organopolysiloxane, in which the vinyl group bonded to the silicon atom is carried by the D group

[0174] Organopolysiloxane B1 = poly(methylhydrogen)siloxane with trimethylsilyl terminal units, viscosity at 25°C about 20 mPa.s

[0175] Organopolysiloxane B2 = polydimethylsiloxane with dimethylhydrogensilyl terminal units, viscosity at 25°C about 7 mPa.s

[0176] Catalyst C = 10% by weight of platinum metal, known as Karstedt catalyst

[0177] Emulsion D = Silicone emulsion containing approximately 59.5% by weight water

[0178] Foaming agent E1 = ammonium bicarbonate

[0179] Foaming agent E2 = finely ground ammonium bicarbonate (NH4HCO3 content = 50% by weight) mixed with silica and polydimethylsiloxane oil

[0180] Polydimethylsiloxane F1 = PDMS, viscosity at 25°C is about 1000 mPa.s

[0181] Polydimethylsiloxane F2 = PDMS, viscosity at 25°C is about 5000 mPa.s

[0182] Polydimethylsiloxane F3 = a mixture of several polydimethylsiloxane oils (PDMS and polydimethylsiloxane with one dimethylvinylsilyl end unit and one trimethylsilyl end unit) with an average viscosity of about 300 mPa.s at 25°C

[0183] Polydimethylsiloxane F4 = a mixture of several polydimethylsiloxane oils (PDMS and polydimethylsiloxane with one dimethylvinylsilyl end unit and one trimethylsilyl end unit) with an average viscosity of about 1000 mPa.s at 25°C

[0184] Polydimethylsiloxane F5 = a mixture of several polydimethylsiloxane oils (PDMS and polydimethylsiloxane with one dimethylvinylsilyl end unit and one trimethylsilyl end unit) with an average viscosity of about 2000 mPa.s at 25°C

[0185] Polydimethylsiloxane F6 = a mixture of several polydimethylsiloxane oils (PDMS and polydimethylsiloxane with one dimethylvinylsilyl end unit and one trimethylsilyl end unit) with an average viscosity of about 20,000 mPa.s at 25°C

[0186] Comparative Example 1:

[0187] The foamable cross-linkable silicone composition was prepared by mixing the components mentioned in Table 1 below:

[0188] Table 1

[0189] The obtained hydrogen-blown silicone foam exhibits high stiffness.

[0190] Comparative Example 2:

[0191] The silicone foam disclosed in Table 14 of the prior art document WO2020 / 072374 was reproduced. The raw materials (linear PDMS, polydimethylsiloxane with dimethylvinylsilyl terminal units, platinum catalyst, crosslinker and ammonium bicarbonate) were mixed and the temperature was kept at 150°C for 30 minutes to allow crosslinking and foaming to occur. The silicone foam was only chemically foamed.

[0192] The feel of this material was greatly improved compared to Comparative Example 1, but the material was found to have a very irregular cell structure.

[0193] Embodiment 1-6:

[0194] A foamable and cross-linkable silicone composition was prepared by mixing the components mentioned in the following Table 2. After mixing, the temperature was maintained at 150° C. for 60 minutes.

[0195] Table 2

[0196] The organic silicone foam obtained according to the present invention is a foam that is simultaneously hydrogen foamed and chemically foamed, and exhibits low density, low weight, a good cell structure, and has a soft anti-shock feel.

[0197] Embodiment 7-9:

[0198] A foamable and cross-linkable silicone composition was prepared by mixing the components mentioned in the following Table 3. After mixing, the temperature was maintained at 150° C. for 60 minutes.

[0199] Table 3

[0200] Embodiment 10-15:

[0201] General composition of hydrogen-blown silicone foam "H2B foam":

[0202] - 67.10% by weight of a mixture of several polydimethylsiloxane oils having dimethylvinylsilyl terminal units, with an average viscosity of about 1,000 mPa.s at 25°C;

[0203] - 11.2% by weight of treated fumed silica;

[0204] - 0.64% by weight of water;

[0205] - 0.64% by weight of emulsifier;

[0206] - 0.03% by weight of Karstedt's catalyst (containing 10% by weight of platinum metal);

[0207] - 20.00% by weight of a poly(methylhydrogen)siloxane having trimethylsilyl terminal units and having an average viscosity of about 20 mPa.s at 25° C.;

[0208] - 0.39% by weight of ethynylcyclohexanol.

[0209] A foamable and cross-linkable silicone composition was prepared by mixing the components mentioned in the following Table 4. After mixing, the temperature was maintained at 150° C. for 60 minutes.

[0210] Table 4

[0211] PVP10 = Polyvinylpyrrolidone; average molecular weight 10,000

[0212] PVP40 = Polyvinylpyrrolidone; average molecular weight 40,000

[0213] Embodiment 16:

[0214] Example 10 was reproduced except that the composition of the hydrogen-blown silicone foam "H2B Foam" contained 14.6% by weight of treated fumed silica instead of 11.2% by weight and 63.7% by weight of the same mixture of polydimethylsiloxane oils instead of 67.1% by weight.

[0215] The silicone foams obtained using the compositions of Examples 7-16 exhibit low density, low weight, and good cell structure.

Claims

1. A silicone foam obtained from a foamable and cross-linkable silicone composition, the foamable and cross-linkable silicone composition comprising: - at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule; - at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule; - at least one hydrosilylation catalyst C; - at least one porogen D which is water, a hydrogel or an aqueous silicone emulsion; - at least one chemical blowing agent E; and - at least one linear polydimethylsiloxane F having a dynamic viscosity at 25° C. of 50 to 100 000 mPa.s.

2. The silicone foam according to claim 1, wherein the organopolysiloxane A comprises a linear organopolysiloxane; preferably, the organopolysiloxane A comprises a terminal dimethylvinylsilyl unit, and more preferably, the organopolysiloxane A is a poly(dimethylsiloxane) comprising a terminal dimethylvinylsilyl group.

3. The organosilicon foam according to claim 1 or claim 2, wherein the organopolysiloxane A comprises C 2-6 Branched organopolysiloxane of alkenyl units; preferably selected from the following silicone resins: -M Vi Q, in which the alkenyl group bonded to the silicon atom is carried by the M group, -MM Vi Q, in which the alkenyl group bonded to the silicon atom is carried by a portion of the M unit, -MD Vi Q, in which the alkenyl group bonded to the silicon atom is carried by the D group, -MDD Vi Q, wherein the alkenyl group bonded to the silicon atom is carried by a portion of the D group, -MM Vi TQ, in which the alkenyl group bonded to the silicon atom is carried by a portion of the M unit, -MM Vi DD Vi Q, in which the hydrogen atoms bonded to the silicon atoms are carried by a portion of the M and D units, - and mixtures thereof, Where M: R 1 3SiO 1 / 2 Siloxy unit, M Vi :Selected from YR 1 2SiO 1 / 2 and Y2R 1 SiO 1 / 2 Siloxy units, D:R 1 2SiO 2 / 2 Siloxy unit, D Vi :Selected from Y2SiO 2 / 2 or YR 1 SiO 2 / 2 Siloxy units of siloxy units, T: formula R 1 SiO 3 / 2 Siloxy units, and Q: formula SiO 4 / 2 The symbol Y is C 2-6 alkenyl, preferably vinyl; and the symbol R 1 It is a monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably selected from an alkyl group having 1 to 8 carbon atoms such as methyl, ethyl or propyl, a cycloalkyl group having 3 to 8 carbon atoms and an aryl group having 6 to 12 carbon atoms.

4. The silicone foam according to any one of claims 1 to 3, wherein the foamable, cross-linkable silicone composition comprises a mixture of at least one linear organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule and at least one branched organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule.

5. The silicone foam according to any one of claims 1 to 4, wherein the foamable and cross-linkable silicone composition comprises a mixture of at least one organic silicon-containing compound B1 having at least three silicon-bonded hydrogen atoms per molecule and at least one organic silicon-containing compound B2 having two silicon-bonded hydrogen atoms per molecule.

6. The organosilicon foam according to any one of claims 1 to 5, wherein the porogen D is an aqueous organosilicon emulsion.

7. The silicone foam according to any one of claims 1 to 5, wherein the porogen D is a mixture of water and at least one emulsifier.

8. The implant according to any one of claims 1 to 7, wherein the chemical foaming agent E is at least one bicarbonate, preferably selected from ammonium bicarbonate (NH4)HCO3, sodium bicarbonate NaHCO3, calcium bicarbonate Ca(HCO3)2 and mixtures thereof; and more preferably, the chemical foaming agent E is ammonium bicarbonate.

9. The silicone foam according to any one of claims 1 to 8, wherein the linear polydimethylsiloxane F is a mixture of linear polydimethylsiloxane (I) and (II) in a weight ratio of (I): (II) of 100:0 to 0:100, Wherein the linear polydimethylsiloxane (I) has the following formula: (CH3)3SiO(SiO(CH3)2) n Si(CH3)3 (I) wherein n is an integer of 50-900, preferably 50-700, and Wherein the linear polydimethylsiloxane (II) has the following formula: <h2 style=";text-align:left;direction:ltr">(CH3)3SiO(SiO(CH3)2)<h2 style=";text-align:left;direction:ltr"> n <h2 style=";text-align:left;direction:ltr"> Si(CH3)2(Y)(II) Where Y is C 2-6 The alkenyl group is preferably a vinyl group, and n is an integer of 50-900, preferably 50-700.

10. The silicone foam according to any one of claims 1 to 9, wherein the foamable and cross-linkable silicone composition further comprises hollow microspheres, preferably hollow glass microspheres.

11. The silicone foam according to any one of claims 1 to 10, wherein the foamable and cross-linkable silicone composition according to the present invention comprises (by weight, relative to the total weight of the composition): - a partial mixture of 1.99% to 98.99% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, at least one hydrosilylation catalyst C and at least one porogen D, the porogen D being water, a hydrogel or an aqueous silicone emulsion; - 0.01% to 2% of at least one chemical blowing agent E; and - 1% to 98% of at least one linear polydimethylsiloxane F having a dynamic viscosity at 25°C of 50 to 100000 mPa.s.

12. The silicone foam according to claim 11, wherein the partial mixture of the at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, the at least one organosilicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule, the at least one hydrosilylation catalyst C and the at least one porogen D has the following composition (by weight relative to the total weight of the partial mixture), wherein the porogen D is water, a hydrogel or an aqueous silicone emulsion: - 40% to 95% of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule; - 1% to 20% of at least one organic silicon-containing compound B having at least two and preferably at least three silicon-bonded hydrogen atoms per molecule; - 2 to 400 ppm of at least one platinum hydrosilylation catalyst C, calculated on the weight of platinum metal; - 0.3% to 2.5% of at least one porogen D, wherein the porogen D is water, hydrogel or aqueous silicone emulsion.

13. A method for preparing an article made of silicone foam, comprising the steps of: 1a) combining the components of a foamable, cross-linkable silicone composition as defined in any one of claims 1 to 12 to provide a precursor for a silicone foam, 1b) filling the silicone foam precursor into a mold, and 1c) foaming and crosslinking the silicone foam precursor.

14. A method for preparing an article comprising a substrate coated with a silicone foam, comprising the steps of: 2a) combining the components of a foamable, cross-linkable silicone composition as defined in any one of claims 1 to 12 to provide a precursor for a silicone foam, 2b) applying the precursor of the silicone foam to a substrate, which is preferably a woven, nonwoven or composite textile, 2c) foaming and crosslinking the silicone foam precursor.

15. A method for additively manufacturing a 3D-shaped article made of silicone foam, comprising the steps of: 3a) printing a portion of the foamable, cross-linkable silicone composition as defined in any one of claims 1 to 12 using a 3D printer to form a deposit in a support material SM, the support material SM being a gel or microgel suitable for 3D-gel printing of silicone foams, the deposit being achieved by means of a device having at least one delivery unit positionable in the x-, y- and z-directions, 3b) partially or completely foaming and crosslinking the printed foamable and cross-linkable silicone composition to obtain a silicone foam deposit within the support material SM, 3c) Optionally, repeating steps a) and b) a number of times until the desired 3D-shape is obtained, 3d) removing the support material SM mechanically or via dissolution in a solvent, and 3e) Recycling of 3D-shaped articles made from silicone foam.

16. Use of the organosilicon foam according to any one of claims 1 to 12, wherein the organosilicon foam is used for producing foamed articles per se, or for producing composite materials or laminates with metals, organic resins or elastic materials in the electronics field, transportation field, aerospace field, energy production field, energy storage field, textile and furniture field and construction field.

17. The use according to claim 12, wherein the use is: - In the electronics market: potting or encapsulating, sealing, bonding or coating various types of components, as well as high-end precision / sensitive electronic devices such as light emitting diodes (LEDs), displays, photovoltaic junction boxes in solar cell modules, diodes, semiconductor devices, relays, sensors, automotive stabilizers, automotive electronic control units (ECUs), - In the transportation sector: automotive, marine or aerospace components, such as hood cushions, engine isolators, seats, vibration & noise damping elements, - In the aerospace field: aerospace thermal insulation, - In the field of energy production and energy storage: high-voltage electrical insulation, insulation of secondary battery packs, insulation of stationary energy storage devices, and insulation of charging stations, in solar photovoltaic cells and modules, windmills, hydroelectric modules, - In the textile and furniture sector: insulating coated and laminated textiles, artificial leather, footwear and clothing insulation, wadding, - In the construction sector: construction electrical protection.

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