HEAT-RESISTANT RUBBER COMPOSITIONS

摘要

A heat-resistant rubber composition that is vulcanizable and comprises a specified ethylene- alpha -olefin-nonconjugated polyene copolymer rubber (A) and an organic peroxide (B). It has a high efficiency of cross-linking with organic peroxides and can provide vulcanized rubber moldings having a high modulus and excellent resistances to environmental deteriorations such as resistance to thermal aging. Another heat-resistant rubber composition that is vulcanizable and comprises 100 parts by weight of a specified ethylene- alpha -olefin-nonconjugated polyene copolymer rubber (A) prepared from ethylene, a C3-C20 alpha -olefin and a vinyl-terminated norbornene compound as the nonconjugated polyene, 0.2-5 parts by weight of an amine age resister (C) and/or a hindered phenol age resister (D), 1-10 parts by weight of a sulfur age resister (E), and an organic peroxide (B). It can provide vulcanized rubber moldings having excellent mechanical and electrical characteristics and remarkably excellent resistance to thermal aging. When the ethylene- alpha -olefin-nonconjugated polyene copolymer rubber (A) is a blend of an ethylene- alpha -olefin-nonconjugated polyene copolymer rubber (A1) having a limiting viscosity [ eta ] of 1-10 dl/g and containing 0.01-2 mol.% of a nonconjugated polyene and another ethylene- alpha -olefin-nonconjugated polyene copolymer rubber (A2) having a limiting viscosity [ eta ] of 0.1-5 dl/g, containing 0.01-2 mol.% of a nonconjugated polyene, and having a limiting viscosity different from that of the component (A), the obtained heat-resistant rubber composition is extremely excellent in flowability and can provide vulcanized moldings having excellent mechanical and electrical characteristics and remarkably excellent resistance to thermal aging.