| 摘要 |
PURPOSE:To provide an optical disc which has a low birefringence index, low hygroscopicity and good transparency, heat distortion temp. and mechanical strength and little causes discoloration, consisting of a resin obtd. by incorporating a small quantity of an antioxidant in a methacrylate resin. CONSTITUTION:An optical disc is obtd. by using, as a material for the main body of a disc, a resin obtd. by using, as a main component, a copolymer (A) composed of 30-60wt% methyl methacrylate, 10-40wt% methacrylate ester wherein a 3-8C hydrocarbon group is attached to an acid radical (e.g. cyclohexyl methacrylate) and 10-50wt% arom. monoalkenyl monomer as essential ingredients and incorporating 0.01-1.5wt% (based on the quantity of component A) antioxidant [e.g. n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] in component A. |
