| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical material improved in strength performances, especially, toughness without detriment to excellent performances such as transparency, a birefringence value, high modulus, high heat resistance, and low water absorptivity by using a hydrogenated styrene polymer having a specified styrene monomer content and a specified weight-average molecular weight. SOLUTION: The optical material is a hydrogenated styrene polymer obtained by hydrogenating at least 80 mol% of the aromatic rings of a styrene polymer comprising (A) structural units of the formula and (B) structural units obtained by (co)polymerizing a styrene monomer with a monomer copolymerizable therewith. In the hydrogenated styrene polymer, the weight ratio Sa/Sb is 0.00001-0.02 (wherein Sa is the amount of component A, and Sb is the amount of component B), the styrene monomer content is at least 80 wt.%, and the weight-average molecular weight is 100,000-600,000. In the formula, (l) and (n) are each 1-20; (m) is 0-5; and R1 to R4 are each Y, a 1-5C alkyl, cyclohexyl, or phenyl.
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