Abstract: The invention provides a semiconductive silicone rubber composition comprising (A) an organopolysiloxane containing at least two aliphatic unsaturated groups, (B) reinforcing silica powder having a specific surface area of at least 50 m.sup.2 /g, (C) a conductive agent, (D) a hydrocarbon oil having a heat loss of up to 30% at 200.degree. C./4 hours, and (E) a curing agent. Cured silicone rubber of the composition has a resistance of 1.times.10.sup.3 to 1.times.10.sup.12 .OMEGA. which remains stable for long-term use. The semiconductive silicone rubber composition is appropriate as a semiconductive roll stock for the manufacture of charging rolls, transfer rolls and developing rolls in business machines.

Abstract: A silicone rubber roll is characteristically prepared on a metallic center by forming a layer of the cured product of a silicone rubber composition which comprises (A) organopolysiloxane, in which the total amount of low molecular weight siloxanes having a degree of polymerization ranging from 3 to 20 is controlled to be at most 10,000 ppm, (B) reinforcing silica powder with a specific surface area of at least 50 m.sup.2 /g, (C) silicone elastomer particles with an average particle size of 200 .mu.m, in which the total amount of low molecular weight siloxanes having a degree of polymerization ranging from 3 to 20 is 2,000 ppm or less, and (D) a curing agent.

Abstract: An addition curing type silicone rubber composition comprising an aliphatic unsaturated group-containing organopolysiloxane, an organohydrogenpolysiloxane and a platinum series catalyst is further blended with a triazine or sulfide control agent to provide a composition which is stable and resistant against premature gelation at room temperature and thus has long-term storage stability. Heating causes the composition to be quickly vulcanized at an acceptable rate into a silicone rubber having satisfactory physical properties.

Abstract: A rubber compound comprising (A) an organopolysiloxane having at least two alkenyl groups in a molecule and (B) reinforcing silica powder is blended with (C) silicone elastomer particles obtained by reacting an organohydrogenpolysiloxane with a vinyl group-containing organopolysiloxane such that the molar ratio of .tbd.SiH group to --CH.dbd.CH.sub.2 group ranges from 1.2 to 5 and (D) a platinum catalyst to form a silicone rubber composition which cures into a product having high rubber strength despite the inclusion of silicone elastomer particles. The composition finds typical use as silicone rubber parts in copying machines.