Patents by Inventor Toshiyuki Kiriyu

Toshiyuki Kiriyu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Process for producing highly pure 3,3',4,4'-biphenyltetracarboxylic acid or dianhydride thereof
    Patent number: 5047560
    Abstract: 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.
    Type: Grant
    Filed: March 9, 1990
    Date of Patent: September 10, 1991
    Assignees: Hitachi, Ltd., Japan Carlit Co., Ltd., Kanto Koatsu
    Inventors: Fusaji Shoji, Nobuo Aoki, Jun Kurita, Tsuyoshi Aoyama, Toshiyuki Kiriyu, Yoshinori Matsuzaki