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. 04, 2009
Filed:
Jul. 21, 2006
Hiroshi Ogawa, Okayama, JP;
Atsushi Okoshi, Okayama, JP;
Masashi Yabuno, Okayama, JP;
Masato Inari, Okayama, JP;
Hiroshi Ogawa, Okayama, JP;
Atsushi Okoshi, Okayama, JP;
Masashi Yabuno, Okayama, JP;
Masato Inari, Okayama, JP;
Mitsubishi Gas Chemical Company, Inc., Tokyo, JP;
Abstract
A method of producing pyromellitic dianhydride. The method includes a step of heating a crude pyromellitic acid in the absence of acetic anhydride to convert a part of pyromellitic acid to pyromellitic anhydride, and a subsequent step of heating the resultant mixture in the presence of acetic anhydride to complete the anhydrization of pyromellitic acid. The pyromellitic dianhydride by the method contains little pyromellitic monoanhydride and other monoanhydrides derived from impurities and is less discolored. The pyromellitic dianhydride has particle properties not causing plugging, etc. during its transportation, storage and use.