# US 5,346,932 A · Silicone rubber composition and method for curing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,346,932 A - Document ID: US5346932A - Status: Granted - Kind: A - Application number: 07/932,138 - Filed: 1992-08-19 - Granted: 1994-09-13 - Earliest claimed: 1990-01-26 - Assignees: Shin-Etsu Chemical Co., Ltd. - Inventors: Masaharu Takahashi; Jun Hatakeyama - Web page: https://patentgrep.com/patent/US5346932A ## CPC - C08K 9/04: Ingredients treated with organic substances {(treated with macromolecular compounds C08K9/08)} - C08K 3/36: Silica - C08L 83/04: Polysiloxanes - C08G 77/20: containing silicon bound to unsaturated aliphatic groups - C08G 77/24: halogen-containing groups - C08G 77/26: nitrogen-containing groups - C08G 77/70: {Siloxanes defined by use of the MDTQ nomenclature} - Y10S 264/46: Molding using an electrical heat - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract The invention provides a silicone rubber composition which is efficiently curable by exposure to microwaves but, different from conventional microwave-curable silicone rubber compositions compounded with a deep-colored energy-absorbing agent, is still capable of being colored in any desired color because the energy-absorbing agent compounded therein is not colored. The energy-absorbing agent used here is a silica or polyorganosilsesquioxane powder having cyanoalkyl or fluoroalkyl groups bonded to the silicon atoms. ## Claims ### Claim 1 A silicone rubber composition curable by irradiation with high-frequency electromagnetic waves which comprise, as a uniform blend: (a) 100 parts by weight of a diorganopolysiloxane represented by the average unit formula R.sub.a SiO.sub.(4-a)/2, in which R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms and a is a positive number in the range from 1.95 to 2.05, and having an average degree of polymerization in the range from 3,000 to 30,000; (b) from 10 to 300 parts by weight of an unmodified finely divided silica filler substantially having a chemical formula of SiO.sub.2 ; (c) from 25 to 100 parts by weight of an organic-modified silica or polyorganosilsesquioxane powder each having cyanoalkyl functional organic groups bonded to the silicon atoms, the content of the functional organic groups being at least 0.3% by weight in the silica or polyorganosilsesquioxane powder; and (d) an organic peroxide curing agent in an amount sufficient to cure the composition when the composition is heated. ### Claim 2 (depends on 1) The silicone rubber composition curable by irradiation with high-frequency electromagnetic waves as claimed in claim 1 in which the component (c) is a polyorganosilsesquioxane powder having functional organic groups bonded to the silicon atoms. ### Claim 3 (depends on 1) The silicone rubber composition curable by irradiation with high-frequency electromagnetic waves as claimed in claim 1 in which the cyanoalkyl group is a 2-cyanoethyl group. ### Claim 4 (depends on 1) The silicone rubber composition as claimed in claim 1 in which the diorganopolysiloxane as the component (a) has an average degree of polymerization in the range from 4,000 to 10,000. ### Claim 5 (depends on 1) The silicone rubber composition as claimed in claim 1 in which the finely divided silica filler as the component (b) has a specific surface area of at least 50 m.sup.2 /g. ### Claim 6 (depends on 1) The silicone rubber composition as claimed in claim 1 in which the amount of the finely divided silica filler as the component (b) is in the range from 25 to 200 parts by weight per 100 parts by weight of the component (a). ### Claim 7 (depends on 2) The silicone rubber composition as claimed in claim 2 in which the polyorganosilsesquioxane powder has an average particle diameter in the range from 0.1 to 50 .mu.m. ### Claim 8 (depends on 1) The silicone rubber composition as claimed in claim 1 in which the amount of the organic peroxide is in the range from 0.5 to 5 parts by weight per 100 parts by weight of the component (a). ### Claim 9 A method for the preparation of a cured silicone rubber article which comprises: (A) compounding into a uniform composition, (a) 100 parts by weight of a diorganopolysiloxane represented by the average unit formula R.sub.a SiO.sub.(4-a)/2, in which R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms and a is a positive number in the range from 1.95 to 2.05, and having an average degree of polymerization in the range from 3,000 to 30,000; (b) from 10 to 300 parts by weight of a finely divided silica filler substantially having a chemical formula of SiO.sub.2 ; (c) from 10 to 200 parts by weight of an organic-modified silica or polyorganosilsesquioxane powder having cyanoalkyl functional organic groups bonded to the silicon atoms, the content of the functional organic groups being at least 0.3% by weight in the silica or polyorganosilsesquioxane powder; and (d) an organic peroxide curing agent in an amount sufficient to cure the composition when the composition is heated; (B) shaping the composition into a form; and (C) exposing the shaped form to ultrahigh frequency electromagnetic waves having a frequency in the range from 900 MHz to 5000 MHz. ### Claim 10 (depends on 9) A cured silicone rubber article prepared by the method of claim 9. ### Claim 11 (depends on 9) A silicone rubber article curable by irradiation with high-frequency waves as claimed in claim 9 in which the component (c) is a polyorganosilsesquioxane powder having functional organic groups bonded to the silicon atoms. ### Claim 12 (depends on 9) A silicon rubber article curable by irradiation with high-frequency electromagnetic waves as claims in claim 9 in which the cyanoalkyl group is a 2-cyanoethyl group. ### Claim 13 (depends on 9) A silicone rubber article as claimed in claim 9 in which the diorganopolysiloxane as the component (a) has an average degree of polymerization in the range from 4,000 to 10,000. ### Claim 14 (depends on 9) A silicone rubber article as claimed in claim 9 in which the finely divided silica filler as the component (b) has a specific surface area of at least 50 m.sup.2 /g. ### Claim 15 (depends on 9) A silicone rubber article as claimed in claim 9 in which the amount of finely divided silica filler as the component (b) is in the range from 25 to 200 parts by weight per 100 parts by weight of the component (a). ### Claim 16 (depends on 9) A silicone rubber article as claimed in claim 9 in which the polyorganosilsesquioxane powder has an average particle diameter in the range form 0.1 to 50 .mu.m. ### Claim 17 (depends on 9) A silicone rubber article as claimed in claim 9 in which the amount of the component (c) is in the range from 25 to 100 parts by weight per 100 parts by weight of the component (a). ### Claim 18 (depends on 9) A silicone rubber article as claimed in claim 9 in which the component (d) is an organic peroxide. ### Claim 19 (depends on 9) A silicone rubber article as claimed in claim 9 in which the amount of the organic peroxide is in the range from 0.5 to 5 parts by weight per 100 parts by weight of the component (a). ### Claim 20 (depends on 1) The silicone rubber composition as claimed in claim 1 in which component (c) is an organic-modified silica powder having functional organic groups bonded to the silicon atoms. ### Claim 21 (depends on 20) A silicone rubber article as claimed in claim 20 in which the organic-modified silica powder has an average particle diameter in the range from 0.1 to 50 .mu.m.