PRODUCTION OF SUBSTRATE FOR INFORMATION RECORDING MEDIUM AND INFORMATION RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To continuously carry out uniform treatment for inhibiting the leaching of glass components from a glass-base substrate for a long time while maintaining the effect of the treatment by bringing the substrate into contact with a molten salt contg. at least a hydrogensulfate and/or a pyrosulfate and inhibiting the crystallization of the molten salt. SOLUTION: The pyrosulfate is a salt of pyrosulfuric acid (H2S2O7) and the hydrogensulfate is that of an alkali metal, an alkaline earth metal, ammonium or the like. A substrate for an information recording medium is immersed in the molten salt or only one face of the substrate is brought into contact with the molten salt. The temp. of the molten salt is preferably the melting temp. or liq. phase temp. to 500 deg.C and below the sublimation temp. of the molten salt. The crystallization of the molten salt is inhibited by feeding water to the molten salt or replenishing the water lost from the molten salt. The degeneration of the glass surface and the occurrence of foreign matter due to the migration of alkali metal ions to the surface are prevented.