Patent ID: 7977443

Claim:
A copolymer rubber that is a random copolymer of ethylene (A), an α-olefin (B) having 3 to 20 carbon atoms and a non-conjugated polyene (C), that has been melt-kneaded with an extruder, and that satisfies the following (1) to (5): (1) the said copolymer rubber contains structural units derived from ethylene (A) and structural units derived from the α-olefin (B) having 3 to 20 carbon atoms in a molar ratio of 40/60 to 95/5 in terms of (A)/(B), (2) the content of structural units derived from the non-conjugated polyene (C) is 0.01 to 5 mol % (provided that the sum of the structural units contained in the copolymer rubber is 100 mol %), (3) the intrinsic viscosity [η] measured in decahydronaphthalene at 135° C. is 1.0 to 5.0 dl/g, (4) the Mw/Mn is in a range of 1 to 8, and (5) P represented by the following formula is from 0.46 to 1.00, P=Ln (intrinsic viscosity [η]) −5.0×10 −5 ×η*(10) (formula 1) wherein Ln is a natural logarithm and η*(10) is viscosity (Pa·sec) measured at 10 rad/sec and at 190° C.