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:
May. 01, 2001
Filed:
Nov. 19, 1997
Applicant:
Inventors:
Akira Utsunomiya, Kitakyushu, JP;
Yoshio Katsuro, Kitakyushu, JP;
Akihiro Takazawa, Kitakyushu, JP;
Takashi Moriyama, Kitakyushu, JP;
Assignee:
Mitsubishi Chemical Corporation, Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
C03C 3/06 ; C03B 8/02 ;
U.S. Cl.
CPC ...
C03C 3/06 ; C03B 8/02 ;
Abstract
A synthetic quartz powder obtained by calcining a powder of silica gel, characterized in that white devitrification spots having sizes of larger than 20 &mgr;m in diameter formed in an ingot obtained by vacuum melting the synthetic quartz powder at a temperature of from 1780 to 1800° C. to form an ingot, followed by maintaining the ingot at a temperature of 1630° C. for 5 hours, are at most 10 spots/50 g.