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. 01, 1989
Filed:
Mar. 17, 1988
Applicant:
Inventors:
Assignees:
Nitto Chemical Industry Co., Ltd, Tokyo, JP;
Mitsubishi Rayon Co., Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C01B / ;
U.S. Cl.
CPC ...
423335 ;
Abstract
There is disclosed a process for producing unsintered cristobalite silica by heating an amorphous silica in the presence of an alkali component, which comprises heating an amorphous silica having a specific surface area (measured according to BET method) of 50 m.sup.2 /g or more at a temperature in the range of 1000.degree. to 1300.degree. C., in the presence of an alkali metal element in a concentration of 5 to 600 ppm to said silica to change it partially or completely into cristobalite and then heating at a temperature of exceeding 1300.degree. C. to eliminate alkali.