Conjugated diolefin-based copolymer rubber and composition thereof

摘要

Conjugated diolefin-based copolymer rubber of a conjugated diolefin and an aromatic vinyl compound, wherein (1) the content of amino groups bound to the rubber (nitrogen content value) is 0.0025 to 0.20 mmol/g of copolymer rubber, (2) the content of the polymerization units of the aromatic vinyl compound is 5 wt% or more and less than 30 wt% based on the copolymer rubber, and the content of vinyl bonds in the polymerization unit of the conjugated diolefin (the total content of a 1,2-bond and a 3,4-bond) is 55 mol% or more based on the polymerization unit of the conjugated diolefin, or the content of the polymerization units of the aromatic vinyl compound is 30 to 50 wt% based on the copolymer rubber and the content of vinyl bonds in the polymerization unit of the conjugated diolefin is 25 to 55 mol% on the polymerization unit of the conjugated diolefin and (3) the molecular weight distribution is polymodal.