HYDROGENATED BLOCK COPOLYMER OF STYRENE BASED AROMATIC HYDROCARBON AND CONJUGATE DIENE, ITS COMPOSITION, AND OPTICAL MOLDING MATERIAL

摘要

PROBLEM TO BE SOLVED: To obtain a copolymer of a styrene based aromatic hydrocarbon and a conjugate diene in which moldability is compatible with the mechanical property of a molding. SOLUTION: The copolymer is obtained by the hydrogenation of unsaturated groups in a block copolymer of the styrene based aromatic hydrocarbon and the conjugate diene. In the copolymer, the chain ends are hydrogenated conjugate diene polymer blocks, the weight ratio of hydrogenated styrene based aromatic hydrocarbon polymer block/hydrogenated conjugate diene polymer block is 70/30-99/1, the hydrogenated rate of unsaturated groups in the copolymer is not less than 90 mol%, and the hydrogenated conjugate diene polymer block is amorphous. A composition containing the copolymar and the use of the composition are also provided.