Process for producing highly pure 3,3',4,4'-biphenyltetracarboxylic acid or dianhydride thereof

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United States of America Patent

PATENT NO 5047560
SERIAL NO

07490917

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Abstract

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Highly pure 3,3',4,4'-biphenyltetracarboxylic acid (BPTA) and dianhydride thereof (BPDA) are produced by heating crude BPTA to give BPDA, treating the BPDA with hot water to give highly pure BPTA, and in the case of highly pure BPDA, heat treating the pure BPTA to give highly pure BPDA.

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Patent Owner(s)

Patent OwnerAddress
HITACHI LTD A CORP OF JAPAN6 KANDA SURUGADAI 4-CHOME CHIYODA-KU TOKYO
JAPAN CARLIT CO LTD A CORP OF JAPAN2-1 MARUNOUCHI-1-CHOME CHIYODA-KU TOKYO
KANTO KOATSU CO LTD A CORP OF JAPAN2-1 MARUNOUCHI-1-CHOME CHIYODA-KU TOKYO

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Aoki, Nobuo Gunma, JP 60 438
Aoyama, Tsuyoshi Shibukawa, JP 15 145
Kiriyu, Toshiyuki Gunma, JP 1 2
Kurita, Jun Shibukawa, JP 3 44
Matsuzaki, Yoshinori Yokohama, JP 9 9
Shoji, Fusaji Yokohama, JP 29 440

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