COPOLYMER, RUBBER COMPOSITIONS, CROSSLIKNED RUBBER, CROSSLINKED FOAM, AND USES OF SAME

摘要

Provided are a rubber composition having sufficient foamability; uses of same; and a copolymer to be contained in the rubber composition.  Also provided are a rubber composition from which a crosslinked foam exhibiting a low specific gravity and excellent shape retention can be produced even when the amount of a non-conjugated polyene used is reduced; and a crosslinked rubber and a crosslinked foam which are produced from this rubber composition.  The copolymer (A) is a copolymer synthesized using a metallocene catalyst, said copolymer comprising units derived from ethylene [A], an a-olefin [B], a non-conjugated polyene [C-1] having, in one molecule, one carbon-carbon double (C=C) bond which is polymerizable by means of a metallocene catalyst, and a non-conjugated polyene [C-2] having, in one molecule, two C=C bonds that are polymerizable by means of a metallocene catalyst.  The copolymer satisfies the requirements: (1) the content of the units derived from the component [B] is 10 to 50 molar%; (2) the total content of the units derived from the component [C-1] and those derived from the component [C-2] is 1.0 to 6.0 molar %; (3) the molar ratio of the units derived from the component [C-1] to the units derived from the component [C-2] is 75/25 to 99.5/0.5; (4)the [ML(1+4) 100°C] value is 10 to 200; and (5) 50 > activation energy of flow (kJ/mol) > 35.