Abstract: An addition curing silicone rubber composition comprising (A) an alkenyl-containing organopolysiloxane, (B) a resinous copolymer composed mainly of R3SiO1/2 units and SiO2 units in a molar ratio between 0.5/1 and 1.5/1 wherein R stands for a monovalent hydrocarbon group and is substantially free of alkenyl groups, (C) a resinous copolymer composed mainly of R′3SiO1/2 units and SiO2 units in a molar ratio between 0.5/1 and 1.5/1 wherein R′ stands for a monovalent hydrocarbon group and includes an alkenyl group, and the total content of alkenyl groups is at least 0.0001 mol/g, (D) an organohydrogenpolysiloxane, and (E) an addition reaction catalyst cures into a silicone rubber sheet that has a satisfactory rubber strength and surface adhesive property.

Abstract: A sealing material comprising (A) an organopoly-siloxane containing at least two alkenyl groups in a molecule, (B) a resinous copolymer composed mainly of R3SiO1/2 and SiO2 units in a molar ratio of 0.5-1.5:1, wherein R is a monovalent hydrocarbon group, and containing 5×10−3 to 1×10−4 mol/g of vinyl groups, (C) an organohydrogenpolysiloxane containing at least two Si—H groups in a molecule, (D) fumed silica having a specific surface area of 150-400 m2/g, and (E) an addition reaction catalyst is suited for sealing one side edge of a polymer electrolyte fuel-cell separator since it has excellent acid resistance and improved compression set in acidic solutions, and exerts satisfactory seal effects.

Abstract: A sealing material for sealing the edges on at least one side of a solid polymer fuel cell separator is provided. This sealing material includes (A) an organopolysiloxane with at least two alkenyl groups bonded to silicon atoms within each molecule, (B) an organohydrogenpolysiloxane with at least two hydrogen atoms bonded to silicon atoms within each molecule, (C) a fumed silica with a specific surface area of 50 to 250 m2/g which has undergone surface treatment with at least two different surface treatment agents, and (D) an addition reaction catalyst. This sealing material displays excellent moldability, heat resistance and elasticity, has a compression set within air and within an acidic aqueous solution which can be suppressed to a low value, and produces an excellent seal, particularly in an acidic aqueous solution.

Abstract: A release agent comprising a perfluoroalkyl ether silazane polymer or a perfluoroalkyl or perfluoroalkyl ether silazane/alkylsilazane copolymer and an organic solvent is suitable for use in molds for silicone base rubber molding. The agent offers effective, long-lasting release properties and ease of molding.

Abstract: A rubber composition comprising (A) an organopolysiloxane end-capped with alkenyldialkylsiloxy, dialkenylalkylsiloxy or trialkenylsiloxy radicals and free of aliphatic unsaturation on any side chain, (B) an organopolysiloxane containing at least three alkenyl radicals on molecular side chains, (C) an organohydrogenpolysiloxane having at least three Si—H radicals, (D) fumed silica, and (E) an addition reaction catalyst forms a seal member having improved strength and reduced compression set and useful for sealing a polymer electrolyte fuel-cell separator.

Abstract: A rubber composition contains an organopolysiloxane having at least two alkenyl radicals, an organohydrogenpolysiloxane having at least three Si—H radicals, a catalyst and optionally, fumed silica and an acid resistant inorganic filler. On a periphery of one side of a polymer electrolyte fuel-cell separator, the composition forms a seal member which allows for little leaching of non-functional organopolysiloxane fraction and has improved acid resistance and compression set.

Abstract: A silicone rubber is produced by curing a silicone rubber composition which includes (A) a curable organopolysiloxane composition and (B) at least one hollow organic resin filler whereby the filler forms cells in an open-cell state. The open-cell state gives the silicone rubber good cushioning property and a low compression set.

Abstract: A silicone rubber is produced by curing a silicone rubber composition which includes (A) a curable organopolysiloxane composition and (B) at least one hollow organic resin filler whereby the filler forms cells in an open-cell state. The open-cell state gives the silicone rubber good cushioning property and a low compression set.

Abstract: A rubber composition comprising (A) a polyisobutylene polymer having an allyl radical at an end, (B) an optional organpolysiloxane, (C) an organohydrogenpolysiloxane having at least two SiH radicals per molecule, and (D) a platinum group metal catalyst forms a seal member on a periphery of one side of a polymer electrolyte fuel-cell separator. Due to improved acid resistance, weather resistance, creep resistance and gas permeability, the seal member remains effective for a long period of time.

Abstract: A sealing material for sealing the edges on at least one side of a solid polymer fuel cell separator is provided. This sealing material includes (A) an organopolysiloxane with at least two alkenyl groups bonded to silicon atoms within each molecule, (B) an organohydrogenpolysiloxane with at least two hydrogen atoms bonded to silicon atoms within each molecule, (C) a fumed silica with a specific surface area of 50 to 250 m2/g which has undergone surface treatment with at least two different surface treatment agents, and (D) an addition reaction catalyst. This sealing material displays excellent moldability, heat resistance and elasticity, has a compression set within air and within an acidic aqueous solution which can be suppressed to a low value, and produces an excellent seal, particularly in an acidic aqueous solution.

Abstract: The primary curing step of molding a heat curable silicone rubber composition loaded with a hollow filler of organic resin under such conditions that the hollow filler is not broken, is followed by the secondary curing step of curing the molded rubber under such conditions that the hollow filler is broken, thereby producing a low specific gravity silicone rubber elastomer having improved heat resistance and minimized changes with time of physical properties, without operational problems.

Abstract: A sealing material comprising (A) an organopolysiloxane containing at least two alkenyl groups in a molecule, (B) a resinous copolymer composed mainly of R3SiO1/2 and SiO2 units in a molar ratio of 0.5-1.5:1, wherein R is a monovalent hydrocarbon group, and containing 5×10−3 to 1×10−4 mol/g of vinyl groups, (C) an organohydrogenpolysiloxane containing at least two Si—H groups in a molecule, (D) fumed silica having a specific surface area of 150-400 m2/g, and (E) an addition reaction catalyst is suited for sealing one side edge of a polymer electrolyte fuel-cell separator since it has excellent acid resistance and improved compression set in acidic solutions, and exerts satisfactory seal effects.

Abstract: A silicone rubber is produced by curing a silicone rubber composition which includes (A) a curable organopolysiloxane composition and (B) at least one hollow organic resin filler whereby the filler forms cells in an open-cell state. The open-cell state gives the silicone rubber good cushioning property and a low compression set.

Abstract: A silicone rubber composition comprising (A) 100 parts by weight of a heat curable organopolysiloxane composition, (B) 0.1-30 parts by weight of unexpanded or expanded organic resin-base microspheres, and (C) 0.5-50 parts by weight of a polyhydric alcohol or derivative thereof cures into a low specific gravity silicone rubber elastomer which experiences a minimal compression set at elevated temperature.

Abstract: The primary curing step of molding a heat curable silicone rubber composition loaded with a hollow filler of organic resin under such conditions that the hollow filler is not broken, is followed by the secondary curing step of curing the molded rubber under such conditions that the hollow filler is broken, thereby producing a low specific gravity silicone rubber elastomer having improved heat resistance and minimized changes with time of physical properties, without operational problems.

Abstract: A silicone rubber composition comprising (A) 100 parts by weight of a heat curable organopolysiloxane composition, (B) 0.1-30 parts by weight of unexpanded or expanded organic resin-base microspheres, and (C) 0.5-50 parts by weight of a polyhydric alcohol or derivative thereof cures into a low specific gravity silicone rubber elastomer which experiences a minimal compression set at elevated temperature.

Abstract: A hollow filler-containing silicone rubber composition comprising 100 parts by weight of a curable organopolysiloxane composition and 0.1-20 parts by weight of a hollow filler in the form of microballoons having a mean particle size of 10-200 &mgr;m and an elasticity of at least 10% is injection molded into a cured silicone rubber part having improved shock-absorbing properties and compression properties as well as weather resistance, freeze resistance and heat resistance inherent to silicone rubber.

Abstract: A silicone rubber composition comprising 100 parts by weight of a thermosetting organopolysiloxane composition and 0.1-200 parts by weight of a hollow filler in the form of microballoons having a mean particle size of 10-200 &mgr;m is suitable for forming a silicone rubber layer around a shaft to provide a heat fixing roll.

Abstract: A thixotropic silicone rubber composition comprising (A) an organopolysiloxane having on the average at least two alkenyl groups in a molecule and a degree of polymerization of up to 1,200, (B) a liquid organohydrogenpolysiloxane having at least two hydrogen atoms each attached to a silicon atom, (C) aluminum hydroxide, (D) an addition reaction catalyst, (E) a thixotropic agent, and optionally (F) a tackifier cures at room temperature or elevated temperature into a silicone rubber having high strength and electrical insulating properties sufficient to serve as a high-voltage electrical insulator. The composition is so thixotropic that it may be used in repairing chipped portions of insulators.

Abstract: A mixture of a first aluminum hydroxide surface treated with a silicon-containing compound and having a mean particle size of 5-20 &mgr;m and a second aluminum hydroxide surface treated with a silicon-containing compound and having a mean particle size of 0.1-2.5 &mgr;m is blended in a silicone rubber composition comprising an organopolysiloxane, finely divided silica, and an organic peroxide. The silicone rubber composition cures into silicone rubber having sufficiently improved properties to serve as high-voltage electrical insulators, even when exposed to air polluted conditions or rigorous weather conditions.