Abstract: A UV-curable silicone composition includes: a polyorganosiloxane (A) having at least two alkenyl groups per molecule and having an alkenyl group content of 0.08 mmol/g or more on an average; a polyorganohydrogensiloxane (B) having per molecule at least three hydrogen atoms bonded to silicon atoms; and a platinum catalyst (C) which is capable of being activated by an ultraviolet light. With respect to a cured product that is obtained by irradiating the composition with ultraviolet light having a wavelength of 365 nm for 45 seconds at an illuminance of 100 mW/cm2 with a diameter of 7.0 mm in a yellow room and subsequently storing the resulting composition at 23° C. for 16 hours, the curing diameter at a depth of 1.8 mm is 10.8 mm or more.

Abstract: To provide a polyorganosiloxane composition whose cured product has uniform good flame retardancy and good physical properties with less discoloring, for example, yellowing, and which has excellent temporal stability when stored. A flame-retardant polyorganosiloxane composition contains: (A) straight-chain polyalkylsiloxane having two or more alkenyl groups in one molecule and having a 10,000 to 1,000,000 mPa·s viscosity (25° C.); (B) resinoid polyorganosiloxane containing a Q unit and having 1.5 or more alkenyl groups on average, mass % of the component (B) being 30 to 80 mass % of the total of the components (A), (B); (C) polyorganohydrogensiloxane having three or more Si—H, an amount of the component (C) being such that Si—H/(total of the alkenyl groups in the components (A), (B)) becomes 1.0 to 3.0 moles; and (D) a catalytic amount of a hydrosilylation reaction catalyst, wherein the total content of phosphorus and an alkali metal is 20 mass ppm or less.

Abstract: A UV-curable silicone composition includes a polyorganosiloxane (A) containing at least two silicon-bonded alkenyl groups in the molecule; a polyorganohydrogensiloxane (B) having a branched or three-dimensional network structure and containing at least three silicon-bonded hydrogen atoms in the molecule; a polyorganohydrogensiloxane (C) having a linear or cyclic structure and containing two silicon-bonded hydrogen atoms in the molecule; and a UV-active addition reaction curing catalyst (D). The component (B) includes a polyorganohydrogensiloxane (E) having a branched or three-dimensional network structure and containing at least one silicon-bonded alkoxy group SiOR0 (R0 is a C1-C5 alkyl group) and at least three silicon-bonded hydrogen atoms in the molecule.

Abstract: A UV-curable silicone composition includes a polyorganosiloxane (A) containing at least one alkenyl group in the molecule and having an alkenyl group content of 0.3 mmol/g or less on average; a polyorganohydrogensiloxane (B) having at least three silicon-bonded hydrogen atoms in the molecule; and a UV-active platinum catalyst (C).

Abstract: There is provided a polyorganosiloxane composition capable of providing a cured product which has low hardness, high transparency, high tensile strength, and low surface tackiness. A curable polyorganosiloxane composition includes: (A) alkenyl group-containing polyorganosiloxane containing straight-chained polyorganosiloxane composed of (A1) both ends alkenyl group polyorganosiloxane having a predetermined viscosity and (A2) polyorganosiloxane having a predetermined viscosity and having 0.6 or more and less than 2 alkenyl groups on average, and (A3) resinous polyorganosiloxane; (B) polyorganohydrogensiloxane composed of (B1) both ends Si—H-containing straight-chained polyorganosiloxane, and (B2) polyorganosiloxane having 3 or more Si—H; and (C) a hydrosilylation reaction catalyst, in mounts that satisfy predetermined relationships.

Abstract: To provide a method of manufacturing a silicone cured product and a silicone cured product which allow generation of a volatile component to be reduced significantly even being exposed to high temperatures of room temperature or more for a long time. A method of manufacturing a silicone cured product includes: curing an additional polyorganosiloxane composition by hydrosilylation reaction under closed atmosphere at a temperature of 40° C. or more and 200° C. or less to obtain a primary cured product; and heating the primary cured product under open atmosphere or reduced pressure at a temperature of 60° C. or more and 160° C. or less, and a silicone cured product in which when heated at 150° C. for 16 hours, a total generation amount of an alcohol having 1 to 3 carbon atoms and an oxide thereof, and an alkyl group-containing silane compound having 1 to 3 carbon atoms is 10 ppm or less.

Abstract: There is provided a polyorganosiloxane composition capable of providing a cured product which has low hardness, high transparency, high tensile strength, and low surface tackiness. A curable polyorganosiloxane composition includes: (A) alkenyl group-containing polyorganosiloxane containing straight-chained polyorganosiloxane composed of (A1) both ends alkenyl group polyorganosiloxane having a predetermined viscosity and (A2) polyorganosiloxane having a predetermined viscosity and having 0.6 or more and less than 2 alkenyl groups on average, and (A3) resinous polyorganosiloxane; (B) polyorganohydrogensiloxane composed of (B1) both ends Si—H-containing straight-chained polyorganosiloxane, and (B2) polyorganosiloxane having 3 or more Si—H; and (C) a hydrosilylation reaction catalyst, in mounts that satisfy predetermined relationships.

Abstract: To provide a polyorganosiloxane composition whose cured product has uniform good flame retardancy and good physical properties with less discoloring, for example, yellowing, and which has excellent temporal stability when stored. A flame-retardant polyorganosiloxane composition contains: (A) straight-chain polyalkylsiloxane having two or more alkenyl groups in one molecule and having a 10,000 to 1,000,000 mPa·s viscosity (25° C.); (B) resinoid polyorganosiloxane containing a Q unit and having 1.5 or more alkenyl groups on average, mass % of the component (B) being 30 to 80 mass % of the total of the components (A), (B); (C) polyorganohydrogensiloxane having three or more Si—H, an amount of the component (C) being such that Si—H/(total of the alkenyl groups in the components (A), (B)) becomes 1.0 to 3.0 moles; and (D) a catalytic amount of a hydrosilylation reaction catalyst, wherein the total content of phosphorus and an alkali metal is 20 mass ppm or less.

Abstract: To provide a polyorganosiloxane composition with good moldability, and a cured product with good mold release property and excellent non-contamination property to the metal mold. A polyorganosiloxane composition for molding includes: (A) a straight-chain polyorganosiloxane having two or more alkenyl groups in one molecule, and having a viscosity (at 25° C.) of 10,000 to 1,000,000 mPa·s; (B) 30 to 80 mass % of a resinoid polyorganosiloxane containing Q units, and having 1.5 or more alkenyl groups on average in one molecule, to a total of the components (A) and (B); (C) a polyorganohydrogensiloxane containing M units and Q units, having a molar ratio of alkoxy groups and Si—H of less than 0.15, and having a mass decrease rate when heated at 150° C. for 30 minutes of 2.0% or less, wherein an amount of the (Si—H/alkenyl groups) is 1.0 to 3.0 mol; and (D) a catalytic amount of a hydrosilylation reaction catalyst.

Abstract: To provide a method of manufacturing a silicone cured product and a silicone cured product which allow generation of a volatile component to be reduced significantly even being exposed to high temperatures of room temperature or more for a long time. A method of manufacturing a silicone cured product includes: curing an additional polyorganosiloxane composition by hydrosilylation reaction under closed atmosphere at a temperature of 40° C. or more and 200° C. or less to obtain a primary cured product; and heating the primary cured product under open atmosphere or reduced pressure at a temperature of 60° C. or more and 160° C. or less, and a silicone cured product in which when heated at 150° C. for 16 hours, a total generation amount of an alcohol having 1 to 3 carbon atoms and an oxide thereof, and an alkyl group-containing silane compound having 1 to 3 carbon atoms is 10 ppm or less.

Abstract: A polyorganosiloxane composition for molding includes: (A) a straight-chain polyorganosiloxane having two or more alkenyl groups and having a viscosity (25° C.) of 10,000 to 500,000 mPa·s; (B) 30 to 80 mass % of a resinoid polyorganosiloxane including M, D, and Q units, at a molar ratio of a:b:c, on average (0.3?a?0.6, 0?b?0.1, 0.4?c?0.7, and a+b+c=1), and having two or more alkenyl groups; (C) an amount of a polyorganohydrogensiloxane having Si-bonded hydrogen atoms, an average degree of polymerization of 10 or more, a content of the Si-bonded hydrogen atoms of 5.0 mmol/g or more and 11.0 mmol/g or less, and a mass decrease rate up to 140° C. by TGA of 2.0 mass % or less so that an amount of the (Si-bonded hydrogen atoms/alkenyl groups) is 1.0 to 3.0 mol; and (D) a hydrosilylation reaction catalyst. A cured product excellent in mold release property is obtained and contamination of a metal mold is prevented.

Abstract: This flame-retardant polyorganosiloxane includes (A) a straight-chain polyorganosiloxane having two or more alkenyl groups in one molecule and whose viscosity (25° C.) is 10,000 to 1,000,000 mPa·s; (B) 30 to 80 mass % of a resinoid polyorganosiloxane which includes Q unit and has 1.5 or more alkenyl groups on average, and in which a molar ratio of alkoxy groups to alkyl groups is 0.030 or less; (C) an amount of a polyorganohydrogensiloxane, whose average degree of polymerization is 10 or more, and in which a Si—H content is 5.0 mmol/g or more, in which Si—H/(a total of alkenyl groups) is 1.0 to 3.0 mol; and (D) a hydrosilylation reaction catalyst. A flame-retardant polyorganosiloxane composition capable of reducing an amount of a platinum-based metal compound is provided.

Abstract: This flame-retardant polyorganosiloxane includes (A) a straight-chain polyorganosiloxane having two or more alkenyl groups in one molecule and whose viscosity (25° C.) is 10,000 to 1,000,000 mPa·s; (B) 30 to 80 mass % of a resinoid polyorganosiloxane which includes Q unit and has 1.5 or more alkenyl groups on average, and in which a molar ratio of alkoxy groups to alkyl groups is 0.030 or less; (C) an amount of a polyorganohydrogensiloxane, whose average degree of polymerization is 10 or more, and in which a Si—H content is 5.0 mmol/g or more, in which Si—H/(a total of alkenyl groups) is 1.0 to 3.0 mol; and (D) a hydrosilylation reaction catalyst. A flame-retardant polyorganosiloxane composition capable of reducing an amount of a platinum-based metal compound is provided.

Abstract: A polyorganosiloxane composition for molding includes: (A) a straight-chain polyorganosiloxane having two or more alkenyl groups and having a viscosity (25° C.) of 10,000 to 500,000 mPa·s; (B) 30 to 80 mass % of a resinoid polyorganosiloxane including M, D, and Q units, at a molar ratio of a:b:c, on average (0.3?a?0.6, 0?b?0.1, 0.4?c?0.7, and a+b+c=1), and having two or more alkenyl groups; (C) an amount of a polyorganohydrogensiloxane having Si-bonded hydrogen atoms, an average degree of polymerization of 10 or more, a content of the Si-bonded hydrogen atoms of 5.0 mmol/g or more and 11.0 mmol/g or less, and a mass decrease rate up to 140° C. by TGA of 2.0 mass % or less so that an amount of the (Si-bonded hydrogen atoms/alkenyl groups) is 1.0 to 3.0 mol; and (D) a hydrosilylation reaction catalyst. A cured product excellent in mold release property is obtained and contamination of a metal mold is prevented.

Abstract: The silicone composition for sealing a semiconductor, comprises: (A) 100 parts of a polyorganosiloxane having one or more alkenyl groups, obtained by reacting (a1) 60 to 99 parts of an organosiloxane containing at least a trifunctional siloxane unit not taking part in a hydrosilylation reaction, with (a2) 40 to 1 parts of an organosiloxane containing a bifunctional siloxane unit having an alkenyl group and/or a monofunctional siloxane unit having an alkenyl group; (B) an amount of a polyorganohydrogensiloxane having two or more hydrogen atoms having a viscosity at 25° C. of 1 to 1000 mPa·s so that an amount of the hydrogen atoms is 0.5 to 3.0 mol per mol of the alkenyl groups; and (C) a platinum-based catalysts, wherein a decrease in storage modulus of a cured product thereof from 25° C. to 50° C. is 40% or more.

Abstract: The silicone composition for sealing a semiconductor, comprises: (A) 100 parts of a polyorganosiloxane having one or more alkenyl groups, obtained by reacting (a1) 60 to 99 parts of an organosiloxane containing at least a trifunctional siloxane unit not taking part in a hydrosilylation reaction, with (a2) 40 to 1 parts of an organosiloxane containing a bifunctional siloxane unit having an alkenyl group and/or a monofunctional siloxane unit having an alkenyl group; (B) an amount of a polyorganohydrogensiloxane having two or more hydrogen atoms having a viscosity at 25° C. of 1 to 1000 mPa·s so that an amount of the hydrogen atoms is 0.5 to 3.0 mol per mol of the alkenyl groups; and (C) a platinum-based catalysts, wherein a decrease in storage modulus of a cured product thereof from 25° C. to 50° C. is 40% or more.

Abstract: The silicone composition for sealing a semiconductor, comprises: (A) 100 parts of a polyorganosiloxane having one or more alkenyl groups, obtained by reacting (a1) 60 to 99 parts of an organosiloxane containing at least a trifunctional siloxane unit not taking part in a hydrosilylation reaction, with (a2) 40 to 1 parts of an organosiloxane containing a bifunctional siloxane unit having an alkenyl group and/or a monofunctional siloxane unit having an alkenyl group; (B) an amount of a polyorganohydrogensiloxane having two or more hydrogen atoms having a viscosity at 25° C. of 1 to 1000 mPa·s so that an amount of the hydrogen atoms is 0.5 to 3.0 mol per mol of the alkenyl groups; and (C) a platinum-based catalyst, wherein a decrease in storage modulus of a cured product thereof from 25° C. to 50° C. is 40% or more.

Abstract: One embodiment is related to a silicone composition for sealing a light emitting element, the composition comprising: (A) a vinyl group-containing organopolysiloxane having a three-dimensional network structure; (B) an organohydrogenpolysiloxane which has at least two hydrogen atoms, each hydrogen atom being bonded to a silicon atom per molecule; and (C) a hydrosilylation catalyst.

Abstract: One embodiment is related to a silicone composition for sealing a light emitting element, the composition comprising: (A) a vinyl group-containing organopolysiloxane having a three-dimensional network structure; (B) an organohydrogenpolysiloxane which has at least two hydrogen atoms, each hydrogen atom being bonded to a silicon atom per molecule; and (C) a hydrosilylation catalyst.

Abstract: A silicone composition for sealing a light emitting element includes: (A) a vinyl group-containing organopolysiloxane having a three-dimensional network structure represented by an average unit formula: (SiO4/2)a(ViR2SiO1/2)b(R3SiO1/2)c (where Vi represents a vinyl group, R's are identical or different substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, and a, b, and c are positive numbers satisfying that a/(a+b+c) is 0.2 to 0.6 and b/(a+b+c) is 0.001 to 0.2); (B) an organohydrogenpolysiloxane which has at least two hydrogen atoms, each hydrogen atom being bonded to a silicon atom per molecule, the organohydrogenpolysiloxane being contained in such an amount that an amount of a hydrogen atom bonded to a silicon atom is 0.3 to 3.0 mol per 1 mol of a vinyl group bonded to a silicon atom in the component (A); and (C) a hydrosilylation catalyst (catalytic amount), wherein a coefficient of linear expansion of the composition after curing is 10×10?6 to 290×10?6/° C.