Patent ID: 7714067
Filing Date: 2010-05-11
Classification: C08F,C08L

Abstract:
1. A block copolymer mixture comprising a branched block copolymer as the main component, said block copolymer mixture comprises from 65 to 75 mass % of a vinyl aromatic hydrocarbon and from 25 to 35 mass % of a conjugated diene as monomer units, a linear block copolymer prior to coupling is formed by coupling living active site represented by the following formulae: wherein each of S1, S2 and S3 is a polymer block consisting of a vinyl aromatic hydrocarbon as monomer units, B is a polymer block consisting of a conjugated diene as monomer units, and Li is a living active site comprising lithium, and the number average molecular weights are S1>S2>S3, and further, (1) molecular weight distribution (Mw/Mn) of a mixture of the polymer blocks S1, S2 and S3 each comprising a vinyl aromatic hydrocarbon as monomer units is within a range of from 3.25 to 6, and (2) in a gel permeation chromatogram of the mixture of the polymer blocks S1, S2 and S3, M1/M3 is within a range of from 13 to 25, and M2/M3 is within a range of from 2 to 4, where M1, M2 and M3 are peak top molecular weights of components corresponding to S1, S2 and S3, respectively, wherein all monomer units are charged as pure monomers and each charge is completely polymerized before the addition of the subsequent charge, and in the gel permeation chromatogram of the mixture of the polymer blocks S1, S2 and S3, the peak top molecular weight M1 corresponding to S1 is within a range of from 80,000 to 220,000, the peak top molecular weight M2 corresponding to S2 is within a range of from 14,000 to 25,000, and the peak top molecular weight M3 corresponding to S3 is within a range of from 3,000 to 12,000.