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:
Aug. 03, 2010
Filed:
Nov. 01, 2007
Applicants:
Junji Kurachi, Osaka, JP;
Akihiro Koyama, Osaka, JP;
Nobuyuki Yamamoto, Osaka, JP;
Inventors:
Assignees:
Nippon Sheet Glass Co., Ltd., Osaka, JP;
Hoya Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C03C 3/087 (2006.01); G11B 5/706 (2006.01);
U.S. Cl.
CPC ...
Abstract
A glass substrate of the present invention for magnetic recording media having high heat resistance and easy chemical strengthening ability at once has not been obtained, which is a glass composition essentially comprising 60 to 70 wt % SiO, 5 to 20 wt % AlO, 0 to 1 wt % LiO, 3 to 18 wt % NaO, 0 to 9 wt % KO, 0 to 10 wt % MgO, 1 to 15 wt % CaO, 0 to 4.5 wt % SrO, 0 to 1 wt % BaO, 0 to 1 wt % TiOand 0 to 1 wt % ZrO, wherein the sum of LiO, NaO and KO is from 5 to 25 wt %, and the sum of MgO, CaO, SrO and BaO is from 5 to 20 wt %.