Patent ID: 8507627

Claim:
An aromatic vinyl compound-conjugated diene compound copolymer obtained by an addition polymerization of an aromatic vinyl compound and a conjugated diene compound in the presence of a polymerization catalyst composition comprising at least one complex selected from the group consisting of a metallocene complex represented by the following general formula (I): wherein M is a lanthanoid element, scandium or yttrium, Cp R is independently a non-substituted or substituted indenyl, R a to R f are independently an alkyl group having a carbon number of 1-3 or a hydrogen atom, L is a neutral Lewis base, and w is an integer of 0-3; a metallocene complex represented by the following general formula (II): wherein M is a lanthanoid element, scandium or yttrium, Cp R is independently a non-substituted or substituted indenyl, X′ is a hydrogen atom, a halogen atom, an alkoxide group, a thiolate group, an amide group, a silyl group or a hydrocarbon group having a carbon number of 1-20, L is a neutral Lewis base, and w is an integer of 0-3; and a half metallocene complex represented by the following general formula (III): wherein M is a lanthanoid element, scandium or yttrium, Cp R′ is a non-substituted or substituted cyclopentadienyl, indenyl or fluorenyl, X is a hydrogen atom, a halogen atom, an alkoxide group, a thiolate group, an amide group, a silyl group or a hydrocarbon group having a carbon number of 1-20, L is a neutral Lewis base, w is an integer of 0-3, and [B] − is a non-coordinate anion, wherein a content of cis-1,4 bond in a conjugated diene compound portion is not less than 80%, and a block quantity of the aromatic vinyl repeating unit portion as measured by NMR is not more than 13% based on the total amount of aromatic vinyl repeating units in the copolymer.