Patent ID: 7700691

Claim:
A vinyl.cis-polybutadiene rubber, comprising cis-polybutadiene rubber, 1,2-polybutadiene, and a polymer substance having a melting point lower than that of the 1,2-polybutadiene and having at least one unsaturated double bond per repeating unit, wherein the polymer substance comprises at least one selected from the group consisting of polyisoprene, crystallizable polybutadiene having a melting point less than 170° C., liquid polybutadiene, a polymeric compound containing an ether group, an epoxy group, a carboxyl group, an ester group, a hydroxyl group, or a carbonyl group, and derivatives of the polymer substance thereof, and wherein the cis-polybutadiene rubber is a matrix component of the vinyl.cis-polybutadiene rubber, and wherein the 1,2-polybutadiene and the polymer substance are dispersed in the cis-polybutadiene rubber matrix component in an adsorbed state, so as to be insoluble in boiling n-hexane.