| 摘要 |
PURPOSE:To obtain a base for information recording media, excellent in heat distortion resistance and moldability and low in hygroscopicity, comprising a copolymer comprising units of four specified compounds and having a ratio of aromatic vinyl compound units to maleic anhydride units in a specified range. CONSTITUTION:A base for information recording media, comprising a copolymer comprising 20-67wt.% phenyl methacrylate units (A), 20-67wt.% methyl methacrylate units (B) and 5-15wt.% maleic anhydride units (C) and 8-25wt.% aromatic vinyl compound units (D), wherein the ratio of units (D) to units (C) is 1:1.1-1:2.5 by mole Because said copolymer contains units of components A, B, C and D each in an amount in a specified range and the ratio of component D to component C is in a specified range, it is excellent in heat distortion resistance and moldability, and can be suitably used as a base for optical information recording media such as video discs, audio discs, memory discs, etc., and it can be also used suitably for optical devices and instruments such as lenses and prisms. |
