| 摘要 |
PURPOSE:To improve the optical characteristic of a substrate for optical recording medium made of a synthetic resin without softening and deforming the substrate by providing a hard layer composed of the oxide of the synthetic resin constituting the substrate on the surface of the substrate by performing an oxidizing process to the resin. CONSTITUTION:It is especially preferable to use polymethyl methacrylate, since a substrate which is excellent in light transmissivity and low in double refraction is required when a synthetic resin is used for the substrate instead of glass. A relatively weak oxidizing process is selected at the time of oxidizing the resin, since the bond of the resin is cut off and light transmissivity is lowered when the oxidizing condition is too strong. In addition, a permanganate and its salt are used as oxidizing agents at the time of oxidizing the resin. Then such a processing method that the formed substrate is brought into contact with a solution containing the oxidizing agents in solid states or the oxidizing agents in a gaseous state. |
