Patent ID: 8586674

Claim:
A method for producing a copolymer rubber composition comprising: a copolymer rubber (1); and a copolymer rubber (2), as a rubber component, wherein the content of the copolymer rubber (1) is 60% by weight or more and 75% by weight or less, and the content of the copolymer rubber (2) is 40% by weight or less and 25% by weight or more, based on 100% by weight of the total of the copolymer rubber (1) and the copolymer rubber (2); and the difference in iodine value between the copolymer rubber (1) and the copolymer rubber (2) is 5 or more and 30 or less, and wherein, the copolymer rubber (1) is an ethylene-α-olefin-nonconjugated polyene copolymer rubber wherein the content of a monomer unit based on ethylene is 50 mol % or more and 70 mol % or less; the content of a monomer unit based on α-olefin is 50 mol % or less and 30 mol % or more (provided that the total of the monomer unit based on ethylene and the monomer unit based on α-olefin is 100 mol %); and the iodine value is 10 or more and 30 or less, and the copolymer rubber (2) is an ethylene-α-olefinic copolymer rubber wherein the content of a monomer unit based on ethylene is more than 70 mol % and 95 mol % or less; the content of a monomer unit based on α-olefin is less than 30 mol % and 5 mol % or more (provided that the total of the monomer unit based on ethylene and the monomer unit based on α-olefin is 100 mol %); and the iodine value is 0 or more and 8 or less, which method comprises manufacturing one of the copolymer rubber (1) and the copolymer rubber (2) in a first reaction tank, feeding the one copolymer rubber manufactured in the first reaction tank to a second reaction tank, and manufacturing the other copolymer rubber in the second reaction tank in the presence of the one copolymer rubber, wherein the two tanks are coupled in series; and wherein the polymerization catalysts used in manufacturing of the copolymer rubber (1) are those containing a vanadium compound selected from the group consisting of VO(OC 2 H 5 )Cl 2 ,VO(OC 2 H 5 ) 0.5 Cl 2.5 ,VO(OC 2 H 5 ) 0.8 Cl 2.2 , and VO(OC 2 H 5 ) 1.8 Cl 1.2 and an organoaluminium compound selected from the group consisting of (C 2 H 5 ) 2 AlCl,(n-C 2 H 5 ) 1.5 ,C 2 H 5 AlCl 2 and (C 2 H 5 ) 3 Al 2 Cl 3 as polymerization catalyst components; and wherein the polymerization catalyst used in manufacturing of the copolymer rubber (2) are those having a vanadium compound selected from the group consisting of VO(O(iso-C 3 H 7 ))Cl 2 ,VO(O(iso-C 3 H 7 )) 0.5 Cl 2.5 ,VO(O(iso-C 3 H 7 )) 1.5 Cl 0.5 and VO(O(iso-C 3 H 7 )) 0.8 Cl 2.2 and the organoaluminium compound selected from the group consisting of (C 2 H 5 ) 2 AlCl,(n-C 2 H 5 ) 1.5 ,C 2 H 5 AlCl 2 , and (C 2 H 5 ) 3 Al 2 Cl 3 as polymerization catalyst components.