Abstract: Disclosed is a rubber composition for separator seal, 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 black having a BET specific surface area of 30 to 120 m2/g, an iodine adsorption value of 30 to 120 mg/g, and a DBP absorption value of 100 to 200 ml/100 g, and (E) an addition reaction catalyst cures into a product which is useful as a separator seal in PEFCs.

Abstract: An adhesive silicone rubber composition comprising (A) 100 pbw of an organopolysiloxane containing at least two silicon-bonded alkenyl radicals, (B) 0.5-20 pbw of an organohydrogenpolysiloxane containing at least two Si—H radicals, (C) a hydrosilylation catalyst, and (D) 0.1-50 pbw of an organosilicon compound having at least one phenyl structure, at least one alicyclic epoxy radical, and at least one Si—H radical is applicable to an electrolyte membrane and a separator in a polymer electrolyte fuel cell to form a firm integrally molded part.

Abstract: A fluorosilicone rubber composition including: (A) an organopolysiloxane containing trifluoropropyl groups and monovalent aliphatic unsaturated hydrocarbon groups, with a viscosity at 25° C. of not less than 10,000 mPa·s, represented by a specific average composition formula, in an amount of 100 parts by mass, (B) a silica-based filler, in an amount of 2 to 100 parts by mass, (C) a hydrotalcite-based inorganic anion exchanger, in an amount of 0.1 to 20 parts by mass, and (D) a curing agent, in an effective amount. Also disclosed is a cured product obtained by curing the composition. The composition forms a molded item that exhibits minimal deterioration in physical properties even when exposed to heat at temperatures of 200° C. or higher.

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) 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 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 silicone rubber composition comprising (A) 100 parts by weight of an organopolysiloxane having a degree of polymerization of 100 or higher and having at least two silicon-bonded alkenyl groups in the molecule; (B) from 3 to 100 parts by weight of a wet silica having the following properties: specific surface area (the BET method) of 50 m2/g or larger, specific surface area (the BET method)/specific surface area (the CTAB method) of from 1.0 to 1.3, and water content of 4% or lower; and (C) an effective amount of a curing agent. The silicone rubber composition can be obtained without foaming even in hot air vulcanization and even if wet silica is used therein, and the silicone rubber composition gives a silicone rubber excellent in electrical properties such as electrical insulating properties.

Abstract: By blending acicular conductive titanium oxide and an antistatic agent having a metal ion-containing moiety in an organopolysiloxane having at least two aliphatic unsaturated groups, there is obtained a silicone rubber composition which is curable with an organic peroxide and/or an organohydrogenpolysiloxane/platinum group catalyst. The composition cures into silicone rubber having a stabilized resistivity in the semiconductive region, especially in the range of 1×103 to 1×1012 &OHgr;-cm, even under high voltages. The composition is thus suitable as a semiconductive roll material for use as charging rolls, transfer rolls and developing rolls.

Abstract: By blending acicular conductive titanium oxide and an antistatic agent having a metal ion-containing moiety in an organopolysiloxane having at least two aliphatic unsaturated groups, there is obtained a silicone rubber composition which is curable with an organic peroxide and/or an organohydrogenpolysiloxane/platinum group catalyst. The composition cures into silicone rubber having a stabilized resistivity in the semiconductive region, especially in the range of 1×103 to 1×1012 &OHgr;-cm, even under high voltages. The composition is thus suitable as a semiconductive roll material for use as charging rolls, transfer rolls and developing rolls.

Abstract: A conductive organopolysiloxane composition is provided which includes (A) 100 parts by weight of an organopolysiloxane; and (B) 0.1 to 800 parts by weight of a conductive material obtained by subjecting a member selected from the group consisting of a conductive metal, a conductive metal compound, a filler surface-treated with a conductive metal and a filler surface-treated with a conductive metal compound, to surface treatment with a compound selected from the group consisting of a compound represented by the formula (1) and a compound represented by the formula (2). ##STR1## wherein R.sup.1 represents --O-- or --NH--, and R.sup.2 represents a hydrogen atom or a phenyl group. This composition is useful for the formation of a silicone rubber having a sufficient electrical conductivity and also stably retainable of electrical conductivity almost without undergoing a change in electrical conductivity even in a high-temperature environment.

Abstract: In a silicone rubber composition comprising an organopolysiloxane, reinforcing silica, and a curing agent, an ester wax, typically having a melting point of 40-150.degree. C., is blended as an abherent. When the composition is molded in a mold, the flow of the composition in the mold and the parting of the cured silicone rubber from the mold are significantly improved.

Abstract: In a silicone rubber composition comprising an organopolysiloxane having at least two aliphatic unsaturated groups and a curing agent, thermal black and/or furnace black having a primary particle diameter of 50-500 nm and a DBP oil absorption of 20-50 cc/100 g is blended. There may be further blended an organopolysiloxane having an ionic group-bearing portion as an antistatic agent and/or a hydrocarbon insulating oil. The composition has a stable resistivity in the semiconductive region and thus is useful as semiconductive rolls.