| 摘要 |
PURPOSE:To obtain a block copolymer which shows a specified composition distribution in the analysis of a composition by high-performance liquid chromatography and excells in kneadability with a thermoplastic resin, etc., by copolymerizing a vinylaromatic hydrocarbon with a conjugated diene in specified conditions. CONSTITUTION:This block copolymer has a polymer segment based on a vinylaromatic hydrocarbon (e.g., styrene) and a polymer segment based on a conjugated diene (e.g., butadiene), and the weight ratio of the vinylaromatic hydrocarbon to the conjugated diene is 10/90-60/40. It is required that the total amount of component A (a component in which the vinylaromatic hydrocarbon content is higher than that of the main peak and the difference between the both is 5wt% or above) and a component B (a component in which the vinylaromatic hydrocarbon content is lower than that of the main peak by at least 5wt%) be 20-80% when determined from a composition analysis by high-performance liquid chromatography.
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