Method of manufacturing an electrically insulating and thermally radiating silicone rubber sheet, and silicone rubber sheets made thereby

Claim 1

A method for manufacturing a rubber sheet which is electrically insulating and thermally radiating, characterized by coating a network insulating material with a fluid silicone rubber composition and then curing said composition, where the fluid silicone rubber composition consists essentially of (a) 100 parts by weight of a polyorganosiloxane having a viscosity at 25°C of from 0.1 to 100 Pa's and having an average unit formula RaRbSiO(4_a-b)/2 wherein each R represents a monovalent hydrocarbon radical free of aliphatic unsaturation or a halogenated monovalent hydrocarbon radical free of aliphatic unsaturation, each R' represents a monovalent aliphatically unsaturated hydrocarbon radical, a has a value from 1.90 to 2.05, b has a value from 0.0005 to 0.1, and the sum of a + b has a value from 1.91 to 2.06, (b) a polyorganohydrogensiloxane having a viscosity at 25°C of 0.0007 to 5 Pa's and having an average unit formula R c H d SiO (4-c-d)/2 wherein R is defined above, the sum of c + d has a value of 1.001 to 3, there is at least two silicon-bonded hydrogen atoms per molecule, and said polyorganohydrogensiloxane is present in an amount such that there are 0.5 to 10 equivalents of silicon-bonded hydrogen atoms per equivalent of aliphatically unsaturated hydrocarbon radical in (a), (c) from 100 to 500 parts by weight of alumina powder, and (d) a catalytic quantity of a platinum-group compound as a catalyst.

Claim 2

A method for manufacturing a rubber sheet which is electrically insulating and thermally radiating, characterized by coating a network insulating material with a fluid silicone rubber composition and then curing said composition, where the fluid silicone rubber composition consists essentially of (a) 100 parts by weight of a polyorganosiloxane having a viscosity at 25°C of from 0.1 to 100 Pa's and having an average unit formula RaRbSiO(4_a-b)/2 wherein each R represents a monovalent hydrocarbon radical free of aliphatic unsaturation or a halogenated monovalent hydrocarbon radical free of aliphatic unsaturation, each R' represents a monovalent aliphatically unsaturated hydrocarbon radical, a has a value from 1.90 to 2.05, b has a value from 0.0005 to 0.1, and the sum of a + b has a value from 1.91 to 2.06, (b) a polyorganohydrogensiloxane having a viscosity at 25°C of 0.0007 to 5 Pa's and having an average unit formula R c H d SiO (4-c-d)/2 wherein R is defined above, the sum of c + d has a value of 1.001 to 3, there is at least two silicon-bonded hydrogen atoms per molecule, and said polyorganohydrogensiloxane is present in an amount such that there are 0.5 to 10 equivalents of silicon-bonded hydrogen atoms per equivalent of aliphatically unsaturated hydrocarbon radical in (a), (c) from 100 to 500 parts by weight of alumina powder, and (d) a catalytic quantity of a platinum-group compound as a catalyst.