| US 7,547,803 B2 | ||
| Process for producing a high purity aromatic polycarboxylic acid | ||
| Shinichi Nagao, Okayama (Japan); Masato Inari, Okayama (Japan); Jitsuo Oishi, Okayama (Japan); Kenji Nakaya, Okayama (Japan); and Hiroshi Machida, Okayama (Japan) | ||
| Assigned to Mitsubishi Gas Chemical Company, Inc., Tokyo (Japan) | ||
| Filed on Jun. 07, 2004, as Appl. No. 10/861,497. | ||
| Claims priority of application No. 2003-176294 (JP), filed on Jun. 20, 2003. | ||
| Prior Publication US 2004/0260052 A1, Dec. 23, 2004 | ||
| Int. Cl. C07C 51/42 (2006.01) | ||
| U.S. Cl. 562—485 | 20 Claims |
| 1. A process for producing a high purity aromatic polycarboxylic acid selected from the group consisting of naphthalenepolycarboxylic
acids and biphenylpolycarboxylic acids by purifying a crude aromatic polycarboxytic acid selected from the group consisting
of crude naphthalenepolycarboxylic acids and crude biphenylpolycarboxylic acids, respectively, which comprises:
(I), in a step of aging, aging a slurry comprising the crude aromatic polycarboxylic acid in a first dispersion medium under
heating at 210 to 290° C. for 10 minutes or longer while being stirred;
(II), in a step of substituting dispersion media, introducing the slurry comprising the aromatic polycarboxylic acid which
has been treated by aging under heating into a column for substituting dispersion media, bringing the slurry into contact
with a second dispersion medium and separating a resultant fluid into a fluid of the first dispersion medium and a slurry
of the second dispersion medium comprising crystals of the aromatic polycarboxylic acid; and
(III), in a step of separating crystals, separating the crystals of the aromatic polycarboxylic acid from the slurry of the
second dispersion medium.
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