ETHYLENE/.ALPHA.-OLEFIN/7-METHYL-1, 6-OCTADIENE COPOLYMER RUBBER AND COMPOSITION OF THE SAME

摘要

The ethylene/.alpha.-olefin/7-methyl-1,6-octadiene copolymer rubber of the invention is a random copolymer rubber prepared using a Group IVB transition metal type catalyst containing a specific zirconium catalyst component, and in this copolymer rubber, a molar ratio of ethylene to .alpha.olefin, a diene content, an intrinsic viscosity ¢?!, an intensity ratio D of Ta.beta. to T.alpha..alpha. in a 13C-NMR spectrum of said copolymer rubber, a B value which is a measure of distribution of each monomers and a glass transition temperature are all within specific ranges. The rubber composition of the invention comprises the above-mentioned random copolymer rubber and a conjugated diene rubber. The random copolymer rubber has high stereoregularity, narrow composition distribution and excellent low-temperature flexibility, and shows extremely high covulcanizability with the conjugated diene rubber. In addition, this random copolymer rubber is excellent in weathering resistance, ozone resistance and thermal aging resistance.