| 摘要 |
The present invention relates to a hydrogenated styrene-conjugated diene-styrene copolymer having excellent toughness, heat distortion temperature, and moldability, a production process therefor, and an optical material, etc. employing the copolymer. The styrene-conjugated diene-styrene block copolymer of the present invention is a hydrogenated styrene-conjugated diene-styrene block copolymer obtained by hydrogenating a styrene-conjugated diene-styrene block copolymer comprising mainly styrene polymer blocks and a conjugated diene polymer block, wherein (A) the hydrogenated styrene polymer block/hydrogenated conjugated diene polymer block ratio by weight is 75/25 to 97/3, (B) the degree of hydrogenation is at least 90%, (C) the number-average molecular weight obtained by a GPC method is 30,000 to 200,000 g/mol, and (D) the hydrogenated styrene-conjugated diene-styrene block copolymer contains 1 to 20 wt % of a high molecular weight component having a molecular weight that is at least three times the number-average molecular weight obtained by the GPC method.
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