| 摘要 |
PURPOSE: Provided is a ternary block copolymer, which has a high tensile strength and is variable in its composition ratio so as to obtain adequate physical properties suitable for its use. CONSTITUTION: The block copolymer is a quintuple block copolymer represented by the formula of pS-pI-pB-pI-pS, in which pS is a vinyl aromatic polymer, pB is a butadiene polymer and pI is an isoprene polymer. In the block copolymer, pB has 70% or more of 1,4-form and a molecular weight of 50,000 to 400,000, the content of pS is 10-50%, and the contents of pB and pI expressed by weights satisfy that pB/pI is 1 or more. Particularly, the vinyl aromatic polymer is a styrene-based polymer.
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