Is a
Patent attributes
Current Assignee
Patent Jurisdiction
Patent Number
Patent Inventor Names
Masato Inari0
Atsushi Okoshi0
Hiroshi Ogawa0
Masashi Yabuno0
Date of Patent
August 4, 2009
0Patent Application Number
114901260
Date Filed
July 21, 2006
0Patent Primary Examiner
Patent 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.
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