Method for producing glass substrate for information storage medium, and information storage medium
AssigneeHoya Corporation
InventorsHazuki Nakae, Toshiharu Mori
Life of this patent
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Abstract
For an information storage medium a glass substrate is produced in a method including the steps of: polishing a glass substrate with a polishing agent applied thereon; and subsequently, chemically strengthening a major surface of the glass substrate. The polishing agent contains cerium oxide at a purity equal to or larger than 99% by mass for CeO2/TREO, and has an alkaline earth metal content having a total mass equal to or smaller than 10 ppm by mass. The step of polishing is performed with a soft polishing pad to polish the glass substrate.
Claims7
A method for producing a glass substrate for an information storage medium including a glass substrate and a magnetic recording layer on a major surface of said glass substrate, comprising:
- polishing said major surface of said glass substrate with a polishing agent applied thereon, wherein said glass substrate is aluminosilicate glass wherein said glass substrate comprises a composition including 0.02-1% by mass of Ce and said polishing comprises coarse polishing and subsequent finishing polishing;
- and
- chemically strengthening said major surface of said glass substrate, wherein said chemically strengthening occurring subsequent to said coarse polishing;
- during said coarse polishing, said polishing agent comprising cerium oxide at a purity equal to or larger than 99% by mass for CeO2/TREO and comprising an alkaline earth metal content having a total mass equal to or smaller than 10 ppm by mass, wherein TREO regards a total amount of rare earth oxide element/elements,
- said coarse polishing being performed with a soft polishing pad to polish said glass substrate.
Dependencies are inferred from the claim text.