Abstract: An olefinic thermoplastic elastomer composition which does not exhibit problems due to a softening agent such as an oil is superior in molding processability. The thermoplastic elastomer composition is produced by a heat crosslinking process of a resin-rubber composition that contains an olefinic and/or diene rubber, an olefinic resin, and a vinyl copolymer. The vinyl copolymer is obtained by copolymerizing 20 wt % or more of a vinyl monomer represented by CH2═CHOCOR1 or CH2═CHOR2 wherein R1 and R2 are alkyl groups having 1-6 carbon atoms. The thermoplastic elastomer composition can include a vinyl copolymer that has not undergone a heat crosslinking process.

Abstract: A silicone-based composite rubber composition having good processability on rolls which is obtained by compounding a rubber-forming polymer (A) comprising a polyorganosiloxane and an organic rubber, a silicon compound (B) having at least two hydrolyzable groups per molecule which are able to undergo hydrolysis and condensation reactions with silanols, and a heavy metal compound, amine, or quaternary ammonium salt (C) which catalyzes the hydrolysis and condensation reactions, and allowing the resulting formulation to undergo hydrolysis and condensation reactions while the formulation is kept being deformed by shearing; a crosslinkable, silicone-based composite rubber composition comprising the silicone-based composite rubber composition having blended therewith an organic rubber-crosslinking agent; and an oil seal and a rubber hose both obtained from the crosslinkable, silicone-based composite rubber composition.