| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive, environmentally friendly ethylenic copolymer rubber which is highly co-vulcanizable and co-crosslinkable with a conjugated diene rubber and exhibits excellent mechanical properties, fatigue resistance, ozone resistance, damping property, etc., and a composition containing the copolymer rubber and the conjugated diene rubber. SOLUTION: The ethylenic copolymer rubber comprises, as constitutional monomers, ethylene, anα-olefin, 5-methyl-1,4-hexadiene and, optionally, anα,ω-diene and has (1) a molar ratio of ethylene/α-olefin of from 40/60 to 90/10, (2) an iodine number of from 5 to 45, (3) a Mooney viscosity of from 15 to 350, (4) a ratio of the weight average molecular weight to the number average molecular weight of from 2.0 to 15, (5) a glass transition temperature of from -80 to -50 deg.C and, optionally, (6) a branching index B of from 0.60 to 0.95. The composition contains the ethylenic copolymer rubber, conjugated diene rubber, vulcanizing agent and/or crosslinking agent.
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