Olefin thermoplastic elastomer composition comprising crystalline polyolefin resin and ethylene/α-olefin/nonconjugated polyene copolymer rubber

An olefin thermoplastic elastomer composition comprising a crystalline polyolefin resin (A) in an amount of not less than 10 parts by weight and less than 60 parts by weight and an ethylene/α-olefin/nonconjugated polyene copolymer rubber (B) which comprises ethylene, an α-olefin of 3 to 20 carbon atoms and a nonconjugated polyene in an amount of not more than 90 parts by weight and more than 40 parts by weight, the total amount of said components (A) and (B) being 100 parts by weight, and which is dynamically heat treated to be partially or completely crosslinked,

• wherein the ethylene/α-olefin/nonconjugated polyene copolymer rubber (B) is obtained by random copolymerizing ethylene, an α-olefin of 3 to 20 carbon atoms and a nonconjugated polyene in the presence of a metallocene catalyst, wherein said polyene contains only one carbon-to-carbon double bond, in one molecule, polymerizable by the metallocene catalyst among carbon-to carbon double bonds, wherein said copolymer rubber (B) has a long-chain branched structure, and has the following properties:
• (1) said copolymer rubber contains (a) units derived from ethylene and (b) units derived from the α-olefin of 3 to 20 carbon atoms in a molar ratio of 40/60 to 95/5;
• (2) the iodine value is in the range of 1 to 50, in terms of grams based on 100 grams of the copolymer rubber (B);
• (3) the intrinsic viscosity (η), as measured in decalin at 135° C., is in the range of 0.1 dl/g to 10 dl/g;
• and
• (4) the ratio gη* of the intrinsic viscosity (η) of said copolymer rubber (B) determined in the property (3) to the intrinsic viscosity (η)blank of a linear ethylene/propylene copolymer having the same weight-average molecular weight, measured by a light scattering method, as the copolymer rubber (B) and having an ethylene content of 70% by mol, (η)/(η)blank, is 0.2 to 0.95.