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:
Jan. 10, 2012
Filed:
Dec. 01, 2009
Mizuho Ishida, Tokyo, JP;
Norihito Shida, Ayutthaya, TH;
Katsuhiro Matsumoto, Tokyo, JP;
Kazuo Mannami, Ayutthaya, TH;
Mizuho Ishida, Tokyo, JP;
Norihito Shida, Ayutthaya, TH;
Katsuhiro Matsumoto, Tokyo, JP;
Kazuo Mannami, Ayutthaya, TH;
Asahi Glass Company, Limited, Tokyo, JP;
Abstract
The present invention relates to a method for producing a glass substrate for a magnetic disk, the method including a step of polishing a main surface of a circular glass plate while supplying a polishing slurry containing a polishing material, in which polishing is performed, after a polishing surface is subjected to dressing treatment, by using a polishing pad having: a first resin foam layer which forms the polishing surface, includes a resin foam having pores with a pore diameter of more than 20 μm and has a thickness of 400 μm or less; and a second resin foam layer which is provided between a platen for fixing the polishing pad and the first resin foam layer, includes a resin foam having pores with a pore diameter of 20 μm or less and has a thickness of 50 to 250 μm, and in which a total thickness of the first resin foam layer and the second resin foam layer is 550 μm or less, and a international rubber hardness degree of the polishing pad measured by the M method according to JIS K6253 is 40 IRHD or more.