| 摘要 |
PURPOSE:To obtain an optical disk causing no double refraction, having superior optical homogeneity and preventing warping and distortion in humid environment by using a copolymer contg. an alkyl substituted styrene monomer and a methacrylic ester monomer as essential components as the base material of the disk. CONSTITUTION:A copolymer contg. an alkyl substituted styrene monomer and a methacrylic ester monomer as essential constituent components and having >=50 deg.C glass transition point is used as a base material. The former monomer is vinyltoluene, tertiary-butyl styrene or the like, the latter monomer is methacrylic ester of 1-4 C alcohol or cyclohexanol, and the preferred amount of the former monomer is 20-40wt% basing on the total amount of both monomers. |
