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:
Dec. 22, 1992
Filed:
May. 26, 1989
Applicant:
Inventors:
Kannosuke Maeda, Ashiya, JP;
Yoshio Aoyama, Kyoto, JP;
Assignee:
Sankyo Kasei Co., Ltd., Osaka, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C01B / ;
U.S. Cl.
CPC ...
2329 / ; 2329 / ; 23304 ; 423203 ; 4235662 ;
Abstract
Disclosed is a process for preparing crystals of anhydrous sodium sulfide, the process being characterized in that the process comprises the steps of heating crystals of polyhydrate of sodium sulfide under a pressure of about 500 torr or less at a temperature varying not more than .+-.about 10.degree. C. from the phase transition point between polyhydrate crystals and monohydrate crystals of sodium sulfide for about 2 hours or longer and further heating the monohydrate under atmospheric or reduced pressure at about 90.degree. to about 200.degree. C. for about 2 hours or longer.