The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 19, 2011
Filed:
Jul. 16, 2009
Mizuho Ishida, Chiyoda-ku, JP;
Kara Yoshida, Chiyoda-ku, JP;
Mizuho Ishida, Chiyoda-ku, JP;
Kara Yoshida, Chiyoda-ku, JP;
Asahi Glass Company, Limited, Tokyo, JP;
Abstract
In the production of a glass substrate for magnetic disk, the present invention provides a method for producing a glass substrate for magnetic disk including a step of polishing a main surface of a circular glass substrate using a polishing pad made of a foamed resin while feeding a polishing liquid containing an abrasive, in which a polishing pad made of a foamed resin having an international rubber hardness of 45 IRHD or less, the hardness being measured at a dry state before contact with a slurry by the M method defined in JIS K6253, is used as a starting polishing pad and polishing is started after a polishing surface of the starting polishing pad is subjected to a dressing treatment to adjust the pad so that an open pore area ratio is 8% or more and an average circle equivalent diameter of open pores is 10 μm or more, in order to suppress an increase in roll-off in the polishing step of the main surface of the circular glass plate.