| 摘要 |
PROBLEM TO BE SOLVED: To obtain a material for an optical disk substrate, having excellent moldability and data reading performances. SOLUTION: This material for an optical disk substrate resin composition composed of a graft polymer (a-1) obtained by polymerizing an aromatic vinyl- based monomer or it with another copolymerizable vinyl-based monomer in the presence of a rubber-like polymer or the graft polymer (a-1) and a (co)polymer (a-2) obtained by polymerizing the aromatic vinyl-based monomer or it with another copolymerizable vinyl-based monomer and is characterized in that material has (1) the weight-average particle diameter of the graft polymer is 0.05-0.15 μm, (2) the content of the rubber-like polymer is 1-50 parts. wt based on 100 parts. wt. of the composition, (3) the graft ratio of the graft polymer (a-1) is 30-150%, (4) the weight-average molecular weight of acetone- soluble part in the composition is >=30,000 and <50,000 and (5) the difference of refractive index between acetone-insoluble part and soluble part in the composition is <0.2. |
