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. 17, 2003
Filed:
Aug. 21, 2001
Mitsubishi Gas Chemical Company, Inc., Tokyo, JP;
Abstract
A process for refined pyromellitic anhydride which comprises dissolving crude pyromellitic acid or crude pyromellitic anhydride in water, then cooling an aqueous solution thus obtained to perform crystallization as pyromellitic acid, then separating a crystal thus obtained from water, then anhydrating the crystal of pyromellitic acid thus separated with heating to produce pyromellitic anhydride, then vaporizing pyromellitic anhydride thus produced, cooling vapor of pyromellitic anhydride thus obtained, and thereby, recovering a refined crystal of pyromellitic anhydride.
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