| 摘要 |
PURPOSE:To make the reduction of a noise level, etc., possible by decreasing the anomaly of double refraction, by using a resin material based no a polycarbonate resin low in a content of low-MW components as the base material of a transparent base of an optical information recording medium. CONSTITUTION:A polycarbonate resin is produced by, for example, a process comprising reacting a dihydric phenol compound (e.g., bisphenol A) with phosgene in the presence of an acid binding agent and a solvent. The obtained polycarbonate resin is purified to produce a polycarbonate resin having an MW (in terms of polystyrene) <=500 and a content of low-MW components <=4wt%. A transparent base is made from the purified polycarbonate resin and an optical information layer is formed on the transparent base to form an optical information recording medium. In this way, the anomaly of double refraction resulting from foreign matter formed by the segregation or condensation of low-MW components in the resin can be reduced. |
