OPTICAL DISK

摘要

PURPOSE:To decrease a pit error rate and to realize a disk having high reliability by allowing the incorporation of just <=1X10<5> pieces/g foreign matter having >=0.5mum grain size into a base material for a disk made of a transparent resin. CONSTITUTION:The incorporation of just <=1X10<5> pieces/g foreign matter size at >=0.5mum grain size is allowed into the base material for the optical disk obtd. by injection molding of the transparent resin. For the above-mentioned purpose, i. the foreign matter is thoroughly removed by distilling or filtering the raw material to be used. ii. The foreign matter sticking to an installation for production is thoroughly removed. iii. The prevention or the like of the intrusion of the foreign matter into the transparent resin from the production thereof up to a molding machine is executed. The content of the foreign matter is thus controlled and the pit error rate is decreased, by which the disk having high reliability is obtd.