| 摘要 |
A novel optical element substrate which comprises a random copolymer comprising, in specific weight proportions, a methyl methacrylate unit, an aromatic vinyl compound unit, an unsaturated aliphatic acid unit and a hexagonal acid anhydride unit of the formula The substrate has excellent heat resistance, thermal stability, transparency, resistance to scratching and metal layer corrosion preventive properties and exhibits advantageously low double refraction and warpage. The novel substrate can be advantageously employed as a substrate for an optical element such as an optical disc, e.g. a digital audio disc, a video disc and a disc capable of being directly read after recording, a mirror, a lens and the like. |
