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:
Jun. 10, 2003
Filed:
May. 09, 2002
Applicant:
Inventors:
Assignee:
Nippon Shokubai Co., Ltd., Osaka, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C07D / ;
U.S. Cl.
CPC ...
C07D / ;
Abstract
A method for producing crystals of pyromellitic dianhydride is disclosed which is characterized by setting the water content of an atmosphere used in handling the crystals of pyromellitic dianhydride at a temperature of not higher than 120° C. at a level of not more than 4 vol. %. Particularly by supplying an inert gas having a water content of not more than 4 vol. % to the step of production, it is made possible to prevent the conversion of pyromellitic dianhydride by hydration very efficiently.