Abstract: For use in a fuel cell separator comprising a separator substrate, a primer layer, and an elastomeric seal, a sealing material comprises a primer composition containing Si—H groups of which the primer layer is formed, and a liquid addition-curable silicone rubber composition containing alkenyl groups and Si—H groups of which the elastomeric seal is formed. A molar ratio of the total amount of Si—H groups to the total amount of alkenyl groups per unit weight of the primer composition and the silicone rubber composition is in the range: 5.0<Si—H/alkenyl<50.0.

Abstract: A rubber composition comprising (A) a liquid alkenyl-containing organopolysiloxane with Mw<100,000, (B) a gum-like organopolysiloxane with Mw?150,000, (C) an organohydrogenpolysiloxane, (D) fumed silica, and (E) an addition reaction catalyst and having a viscosity of 20-200 Pa-s at a shear rate of 10 s?1 and 25° C. is effectively injection moldable into a cured product which is useful as a separator seal in PEFCs.

Abstract: A rubber composition comprising (A) an alkenyl-containing organopolysiloxane, (B) a silicone resinous copolymer, (C) an organohydrogenpolysiloxane, (D) fumed silica having a BET specific surface area of 50-400 m2/g, (E) carbon powder having a BET specific surface area of 30-150 m2/g, and (F) an addition reaction catalyst cures into a product which is useful as a separator seal in PEFCs. The rubber has a reduced compression set even in an acidic atmosphere or in contact with LLC, and the rubber itself has strength and good adhesion to separator substrates. The separator provides excellent seal performance over a long term.

Abstract: A rubber composition comprising (A) a mixture of two or more alkenyl-containing liquid organopolysiloxanes having different weight average molecular weights, (B) an organohydrogenpolysiloxane, (C) fumed silica having a BET specific surface area of 50-400 m2/g, (D) carbon powder, and (E) an addition reaction catalyst cures into a product which is useful as a separator seal in PEFCs. The rubber has a reduced compression set even in an acidic atmosphere or in contact with LLC, and the rubber itself has strength and good adhesion to separator substrates. The separator provides excellent seal performance over a long term.

Abstract: A heat fixing roll or belt having a silicone rubber layer which is formed by curing a silicone rubber composition comprising (A) 100 pbw of an organopolysiloxane having at least two silicon-bonded alkenyl radicals in a molecule, (B) 20-500 pbw of a metallic silicon powder having an average particle size of up to 100 ?m, and (C) an effective amount of a curing agent. The silicone rubber layer has a high heat conductivity and long-term temperature durability.

Abstract: In an addition curable silicone rubber composition, an organohydrogenpolysiloxane containing at least two SiH groups in a molecule, synthesized through cohydrolytic condensation reaction of an SiH-containing organoalkoxysilane and an SiH-free organoalkoxysilane, is included as a crosslinker. An SiH-functional low-molecular-weight siloxane fraction is substantially absent in the cured composition.

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: An addition curing silicone rubber composition and a cured product thereof are provided. In this composition, amount of the low molecular weight siloxane component volatilizing from the cured product has been reduced, and as a consequence, this composition is free from the problems such as clouding or haze, contact fault, adhesion failure, and hydrophobicization of the surface caused by the deposition of the volatilized low-molecular weight siloxane component on the surrounding surfaces. More specifically, the addition curing silicone rubber composition comprises; (A) 100 parts by weight of a polyorganosiloxane containing, on average, at least two alkenyl groups which are bonded to silicon atom; (B) 0.

Abstract: A primer composition comprising a compound containing an epoxy group, a Si—H group, and an aromatic ring per molecule, and a solvent is effective for assisting in integral molding or bonding a silicone rubber to an adherend of gold, silver or platinum.

Abstract: A heat fixing roll or belt having a silicone rubber layer which is formed by curing a silicone rubber composition comprising (A) 100 pbw of an organopolysiloxane having at least two silicon-bonded alkenyl radicals in a molecule, (B) 20-500 pbw of a metallic silicon powder having an average particle size of up to 100 ?m, and (C) an effective amount of a curing agent. The silicone rubber layer has a high heat conductivity and long-term temperature durability.

Abstract: A highly heat conductive silicone rubber composition is provided comprising (A) 100 pbw of a heat curable organopolysiloxane composition and (B) 10-2,000 pbw of a metallic silicon powder having an average particle size of 2-100 ?m. It cures into a product having a high thermal conductivity, heat resistance and low compression set and remains fully stable during shelf storage. It is useful as a heat conducting or dissipating material in automobiles and electric and electronic equipment where heat resistance, heat conductivity and rubber elasticity are required.

Abstract: A silicone rubber composition comprising (A) a normally liquid organopolysiloxane having at least two silicon atom-bonded alkenyl radicals, (B) a liquid organohydrogenpolysiloxane having at least two Si—H radicals, (C) a blend of two inorganic powders selected from three highly heat conductive inorganic powders which form 30% slurries at pH at least 8, 6 to less than 8, and less than 6, and (D) an addition reaction catalyst cures into a silicone rubber having a high thermal conductivity and heat resistance and is suited for fixing rolls or belts in copiers.

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: 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 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 primer composition comprising a compound containing an epoxy group, a Si—H group, and an aromatic ring per molecule, and a solvent is effective for assisting in integral molding or bonding a silicone rubber to an adherend of gold, silver or platinum.

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 silicone rubber composition comprising (A) a normally liquid organopolysiloxane having at least two silicon atom-bonded alkenyl radicals, (B) a liquid organohydrogenpolysiloxane having at least two Si—H radicals, (C) a blend of two inorganic powders selected from three highly heat conductive inorganic powders which form 30% slurries at pH at least 8, 6 to less than 8, and less than 6, and (D) an addition reaction catalyst cures into a silicone rubber having a high thermal conductivity and heat resistance and is suited for fixing rolls or belts in copiers.

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 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.