| 摘要 |
PURPOSE:To enable the recording and reproducing of information from a protective film and to obtain a card-shaped recording medium having high reliability by forming the protective layer of the recording medium of a film which consists of a polycarbonate resin having 20,000-28,000mol.wt. and in which the number of opaque foreign matter of >=3mu diameter contained per gram of the resin is <=5,000. CONSTITUTION:A polyethylene film which has a prescribed thickness and is coated with silver particles dispersed in gelatin is used as the optical recording medium after the film is subjected to a solidifying treatment. This film is cut to a prescribed size and is stuck to vinyl chloride. A polycarbonate film to serve as a protective film is stuck onto this film from above to form the card- shaped recording medium. The film to serve as the protective layer is formed of the polycarbonate resin having 20,000-25,000mol.wt. by extrusion or injection molding and is decreased in double refractions and fluctuations; in addition, the number of the opaque foreign matter of >=3mu diameter contained therein per gram of the resin is confined to <=5,000 pieces. |
