Manufacturing Method for Glass Substrate for Information Recording Medium
An aspect of the invention is directed to a method for manufacturing a glass substrate for an information recording medium including: a polishing step of polishing a surface of a raw glass plate, with use of a polishing solution containing a polishing agent and water; and a chemically reinforcing step of reinforcing the polished surface of the raw glass plate which has undergone the polishing step, with use of a chemically reinforcing treatment solution. The polishing step is a step of using, as the polishing agent, a polishing agent containing CeO 2 , and of performing polishing in such a manner that the effective amount of CeO 2 per unit area of the surface of the raw glass plate to be used in the polishing is in the range of from 0.05 to 0.5 μg/cm 2 .
1 . A method for manufacturing a glass substrate for an information recording medium, comprising:
a polishing step of polishing a surface of a raw glass plate, with use of a polishing solution containing a polishing agent and water; and
a chemically reinforcing step of reinforcing the surface of the raw glass plate which has undergone the polishing step, with use of a chemically reinforcing treatment solution, wherein
the polishing step is a step of using, as the polishing agent, a polishing agent containing CeO2, and of performing polishing in such a manner that an effective amount of CeO2 per unit area of the surface of the raw glass plate to be used in the polishing is in the range of from 0.05 to 0.5 μg/cm2.
2 . The method for manufacturing a glass substrate for an information recording medium according to claim 1 , wherein
a content of the polishing agent in the polishing solution is in the range of from 3 to 7 mass % with respect to the water,
the polishing solution contains a dispersant having a negative electric charge, and a content of the dispersant is in the range of from 0.25 to 5 parts by mass with respect to 100 parts by mass of CeO2.
3 . The method for manufacturing a glass substrate for an information recording medium according to claim 1 or claim 2 , wherein the polishing step is at least one selected from the group consisting of polishing a principal surface of the raw glass plate, polishing an inner circumferential end surface of the raw glass plate, and polishing an outer circumferential end surface of the raw glass plate.
4 . The method for manufacturing a glass substrate for an information recording medium according to claim 1 , wherein
the dispersant is a material of at least one kind selected from the group consisting of polycarboxylic acids and derivatives thereof.
5 . The method for manufacturing a glass substrate for an information recording medium according to claim 1 , wherein
the polishing agent has a maximum value in a particle diameter distribution measured by a laser diffraction/scattering method of 3.5 μm or smaller, and has D50 in the particle size distribution measured by the laser diffraction/scattering method in the range of from 0.5 to 1.5 μm, D50 representing a particle diameter corresponding to 50 vol % of an accumulation curve.
6 . The method for manufacturing a glass substrate for an information recording medium according to claim 1 , wherein
a content of CeO2 is 60 mass % or more with respect to a total mass of solid content of the polishing solution.
7 . The method for manufacturing a glass substrate for an information recording medium according to claim 1 , further comprising:
a step of grinding the raw glass plate prior to the polishing step, wherein an arithmetic average roughness Ra of a surface of the raw glass plate which has undergone the grinding is 0.1 μm or smaller.