| 摘要 |
A block copolymer comprising at least one polymer block A comprising conjugated diene monomer units, and at least one polymer block B comprising conjugated diene monomer units and aromatic vinyl monomer units. This block copolymer is characterized in that (1) the polymer block A has a glass transition temperature of -88°C to -45°C, (2) the polymer block B has a glass transition temperature of 30°C to 90°C, (3) the content of aromatic vinyl monomer units in the whole block copolymer is 3-52 wt.%, (4) the aromatic vinyl block ratio in the whole block copolymer is smaller than 69 wt.%, and (5) the viscosity of a 5 wt.% solution of the block copolymer in styrene is 30-80 mPa·s. The block copolymer is useful as a resin modifier.
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