| 摘要 |
PURPOSE:To suppress the generation of silver streaks on a disk surface by incorporating a specified volatile component into copolymers composed of methylmethacrylate units and alkylester acrylate units having alkyl groups of 2 - 8C. CONSTITUTION:Such a volatile component having 70 - 200 deg.C boiling point at 760 mmHg and 7 - 10(cal/cm<3>)<1/2> solubility parameter is incorporated by 1000 - 10000 ppm to the copolymers composed of methylmethacrylate units and alkylester acrylate units having alkyl groups of 2 - 8C. The used volatile component is preferably, toluene, xylene, ethylbenzene, alpha-methylstyrene, methylmethacrylate, methylacrylate, and ethylacrylate. One of these or mixture of two or more kinds of these may be used as the volatile component. Thereby, the generation of silver streaks on a disk surface in a high-temp. high-cycle forming process can be suppressed, and the productivity of the disk is largely improved. |
