| 摘要 |
PURPOSE:To reduce rate of moisture absorption and to improve heat resistance by producing a substrate from copolymers essentially comprising methacrylate deriv. having a norbornane group and/or methacrylate deriv. having an adamantine group. CONSTITUTION:The optical disk substrate consists of copolymers essentially comprising methyl methacrylate, methacrylate deriv. having a norbornane group and/or methacrylate deriv. having an adamantane group. The methacrylate deriv. having a norbornane group is such a compound expressed by formulae I and II, wherein m is an integer from 0 to 2. By this method, moisture resistance and heat resistance of the substrate can be improved without losing low double refraction of polymethyl methacrylate (PMMA), which is an advantage of this material. |
