To provide a glass substrate having an excellent surface smoothness and flatness and no bubbles, by finding and using a clarifier suitable for manufacturing a molded glass substrate for information recording media which serves as an alternative to conventional clarifiers, and its manufacturing process.
The manufacturing process comprises steps wherein a glass material composition composing the glass substrate is melted, the molten glass material composition is molded in a metal mold into the glass substrate, the molded glass substrate is taken out from the metal mold, and the obtained glass substrate is annealed. To the molten glass material composition, at least one compound chosen from the group consisting of CeO2, Pr6O11 and Tb4O7 is added as the clarifier.
KOBAYASHI RYOJI
ONODA MINORU
MATSUSHITA ELECTRIC IND CO LTD
Kazuo Abe
Denichi Hashimoto