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:
Sep. 24, 2002
Filed:
May. 17, 2001
Ryusuke Shigematsu, Ibaraki-ken, JP;
Masayoshi Hayashi, Ibaraki-ken, JP;
Shinichi Nagao, Okayama-ken, JP;
Jitsuo Oishi, Okayama-ken, JP;
Akio Hashimoto, Ibaraki-ken, JP;
Mitsubishi Gas Chemical Company, Inc., Chiyoda-ku, JP;
Abstract
A process for producing a high purity aromatic polycarboxylic acid by purify a crude aromatic polycarboxylic acid in accordance with the steps of (I) forming an amine salt of an aromatic polycarboxylic acid from the crude polycarboxylic acid and an amine, (II) continuously decomposing the salt in a salt decomposition reactor in operations of (i) supplying an aqueous solution of the amine salt of an organic polycarboxylic acid formed in the step of forming a salt, (ii) removing the amine and water by distillation under heating and (iii) taking out a slurry containing crystallized aromatic polycarboxylic acid, and (III) separating and recovering crystals of the aromatic polycarboxylic acid from the slurry which is taken out in the step of decomposing the salt. A high purity aromatic polycarboxylic acid having excellent hue and large particle diameters can be produced from a crude aromatic polycarboxylic acid industrially with stability at a low cost of production in accordance with a process having a simple construction.