| 摘要 |
PURPOSE:The titled rubber having a specific composition, specified molecular weight distribution and Mooney viscosity, obtained by copolymerizing styrene with butadiene in a hydrocarbon solvent containing a Lewis base by the use of an organolithium compound as a polymerization initiator, adding a polyfunctional coupling agent to the reaction mixture. CONSTITUTION:Styrene is copolymerized with buradiene in a hydrocarbon solvent containing at least one Lewis salt by the use of an organolithium compound as a polymerization initiator, and then, a polyfunctional coupling agent having >=3 reactive sites is added to the reaction mixture, to give copolymer rubber having 40-150 Mooney viscosity (ML1+4, 100 deg.C), 28-55wt% bonded styrene, 16-40wt% vinyl bond content of butadiene, bi-modal of molecular weight distribution, molecular weight distribution of bi-modal satisfying a relationship between Mw-bi and Mw-mono shown by the formula Mw-bi/Mw-mono >=1.3 wherein Mw-mono is weight-average molecular weight of copolymer rubber having the same structural factor and, Mw-bi is weight-average molecular weight of copolymer rubber having molecular weight distribution of bi-modal, having >=50wt% styrene single chain and <=5.0wt% chain of >=8 styrene monomer sequences.
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