| 摘要 |
PURPOSE:A block copolymer excellent in impact resistance, regidity, low-temperature stretchability, and environmetal cracking resistance, prepared by adjoining polymer blocks of a vinylaromatic hydrocarbon and a conjugated diene of a specified composition and polymer blocks of a vinylaromatic hydrocarbon to each other. CONSTITUTION:A block copolymer having at least one polymer segment A comprising (a) 60-95wt% vinylaromatic hydrocarbon and (b) 40-5wt% conjugated diene and having a content of component (a) of 90-100wt%, at least one polymer segment B having a content of component (a) of 70-90wt%, and at least one polymer segment C having a content of component (a) of 0-75wt%, wherein the total amount (A') of the part corresponding to segment A is 20-80pts.wt., the total (B') of the part corresponding to segment B is 10pts.wt. or above, the total (C') of the part corresponding to segment C is 10pts.wt. or above, B'+C'= 20-80pts.wt., and A'+B'+C'=100pts.wt. and segment B is adjacent to segment A.
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