| 摘要 |
A novel block copolymer mixture of conjugated diene (C.D.) and vinylaromatic hydrocarbon (V.H.) having a superior transparency and impact-resistance is produced by the following two step polymerizations using an organolithium compound as a catalyst and a solvent consisting mainly of an aliphatic hydrocarbon: a first step (A) of preparing a living (co)polymer of C.D. or C.D. and V.H., by polymerizing the monomer(s) in a ratio by weight of V.H. to C.D. of 0/100 to 60/40 and in an amount of 1 to 80% by weight of total monomers to be used, in the presence of said catalyst and solvent, and a second step (B) of preparing V.H. polymer or block copolymer of V.H. and C.D., by adding to said living (co)polymer, remaining monomer(s), in a ratio by weight of V.H. to C.D. of 100/0 to 65/35 and in an amount of 99 to 20% by weight of total monomers to be used, and said catalyst and solvent, and polymerizing the remaining monomer(s) to obtain a block copolymer mixture, this block copolymer mixture having a ratio of V.H. content of ultimate block copolymers to that of the (co)polymers obtained only in step (B), of at least 1/1.8, and a ratio of V.H. portion to C.D. portion of 60/40 to 95/5.
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