Nitrile group-containing highly saturated copolymer rubber

摘要

A nitrile group-containing highly saturated copolymer rubber having an iodine value of 80 or less and containing a caprate in 0.01 to 0.4 wt %. Preferably, the caprate is an alkaline earth metal caprate or Group XIII metal caprate. According to present invention, it is possible to provide a nitrile group-containing highly saturated copolymer rubber improved in mold fouling resistance while maintaining good normal state physical properties and heat resistance when being made into a cross-linked product.