Rubber vulcanizate, process for its production, and polymer composition, rubber composition and vulcanizable rubber composition used in the process

摘要

This invention provides a rubber vulcanizate of a nitrile group-containing copolymer rubber, exhibiting enhanced ozone resistance. The rubber vulcanizate is made by heat-treating a polymer composition comprising 40-90 wt. % of a nitrile group-containing copolymer rubber (1), and 60-10 wt. % of particles having an average particle diameter of not larger than 10 μm comprised of an acrylic resin (2) comprising methyl acrylate or methacrylate units as the main structural units and containing not larger than 0.01 eq. wt., per 100 g of acrylic resin (2), of a crosslink-forming functional group, at a temperature in the range of (T+20)° C. to (T+90)° C. wherein T is a temperature which is selected from glass transition temperature of acrylic resin (2) and melting temperature of acrylic resin (2), and is higher than the other of the two temperatures, to thereby prepare a rubber composition; incorporating a vulcanizer in the rubber composition; and vulcanizing the thus-obtained vulcanizable rubber composition.