| 摘要 |
A process for preparing an ethylene/ alpha -olefin/norbornene nonconjugated polyene random copolymer, comprising preparing an ethylene random copolymer simultaneously meeting the following requirements (1) to (5): (1) the molar ratio of ethylene (a) to an alpha -olefin (b) having 3 to 20 carbon atoms ranges from 40:60 to 95:5; (2) a given amount of non conjugated polyene (c) has a norbornene skeleton; (3) the available network chain density nu is not less than 1.5 x 10<20>/cm<3> after press cross-linking of the copolymer using a dicumyl peroxyde; (4) the ratio of the rate gamma 1 of shear showing a shearing stress of 0.4 x 10<6> dyn/cm<2> as determined from the melt flow curve at 100 DEG C and the rate gamma 2 of shear showing a shearing stress of 2.4 x 10<6> dyn/cm<2>, that is gamma 2/ gamma 1 and the available network chain density nu has a relationship represented by the following general formula: 0.04 x 10<-19> ≤ Log( gamma 2/ gamma 1)/ nu ≤ 0.20 x 10<-19>; and (5) the intrinsic viscosity Ä eta Ü ranges from 0.5 to 10 dl/g as measured in decalin at 135 DEG C. The copolymer has excellent cross-linkability, can be cross-linked with a small amount of a peroxide or the like, and a cross-linked rubber composition prepared using this copolymer has excellent heat aging resistance, mechanical strength, weather resistance, and oxone resistance. |
