ETHYLENE/ALPHA-OLEFIN/UNCONJUGATED POLYENE COPOLYMER RUBBER, RUBBER COMPOSITION FOR SEALING, MOLDED RUBBER FOR SEALING, AND PROCESS FOR PRODUCING THE MOLDED RUBBER PART

The present invention relates to an ethylene- alpha -olefin-non-conjugated polyene copolymer rubber comprising ethylene, an alpha -olefin having 3 to 20 carbon atoms and a non-conjugated polyene, characterized in that: (i) the intrinsic viscosity Ä eta Ü as measured in decalin solvent at 135 DEG C is 1.5 to 5.0 dl/g; (ii) the g eta * or g' value is 0.6 to 0.9, wherein the g eta * value is defined as a ratio of the intrinsic viscosity Ä eta Ü as measured in (i) above to an intrinsic viscosity Ä eta Üblank as measured in decalin solvent at 135 DEG C of a linear ethylene-propylene copolymer having an ethylene content of 70% by mole which has the same weight average molecular weight (according to light scattering method) as the ethylene- alpha -olefin-non-conjugated polyene copolymer rubber having the intrinsic viscosity Ä eta Ü (Ä eta Ü/Ä eta Üblank), and the g' value is defined as a ratio of the intrinsic viscosity Ä eta Ü as measured in (i) above to an intrinsic viscosity Ä eta Üblank' as reduced to a linear ethylene-propylene copolymer having an ethylene content of 70% by mole, which is determined by gel permeation chromatography (140 DEG C, o-dichlorobenzene solvent) of the ethylene- alpha -olefin-non-conjugated polyene copolymer (g'=Ä eta Ü/Ä eta Üblank'); (iii) the Mw/Mn is 3.0 to 50; (iv) the iodine value is 10 to 40; (v) the molar ratio of ethylene to the alpha -olefin having 3 to 20 carbon atoms is 40/60 to 95/5; and (vi) the intensity ratio D of T alpha beta to T alpha alpha in C-NMR spectrum (T alpha beta /T alpha alpha ) is 0.5 or less, as well as to a rubber composition for sealing using said copolymer rubber, a molded rubber part for sealing, and a process for preparing said molded part.