JP2004026570A5 - - Google Patents

Claims (8)

A method for producing a glass substrate for an information recording medium, comprising:
Melting the glass raw material composition constituting the glass substrate;
Processing the molten glass raw material composition into the shape of a molding gob ;
Forming the softened gob into a glass substrate using a mold; and
Slowly cooling the glass substrate;
Removing the glass substrate from the mold;
Have
Manufacturing method characterized by adding the _{CeO 2,} Pr _{6 O 11,} and _Tb 4 _{O 7} of at least one compound selected from the group consisting of a refining agent to the glass raw material molten composition.   The production method according to claim 1, wherein the amount of the compound added as the fining agent is in the range of 0.02 mol% to 2.0 mol%.   The production method according to claim 2, wherein the amount of the compound added as the fining agent is in the range of 0.05 mol% to 1.0 mol%.   The manufacturing method according to claim 1, wherein the mold has a protective film made of a noble metal on the surface of the mold.   The manufacturing method according to claim 4, wherein the protective film contains at least one element selected from the group consisting of Pt, Ir, Re, Os, Pd, Rh, and Ru.   The manufacturing method according to claim 5, wherein the protective film further includes at least one element selected from the group consisting of Ta, Hf, W, and Au. A glass substrate for an information recording medium obtained by molding with a mold, wherein the glass substrate is produced by the production method according to any one of claims 1 to 6. . An information magnetic recording medium having a magnetic layer capable of at least magnetic recording on a substrate,
An information magnetic recording medium, wherein the substrate is the glass substrate for an information recording medium according to claim 7.