Patents by Inventor Taketoshi Kitoh

Taketoshi Kitoh 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 preparing bisphenol A
    Patent number: 6329556
    Abstract: This invention relates to a process for preparing bisphenol A by the condensation of phenol with acetone in the presence of cation exchange resin obtained by sulfonating copolymers of monovinyl monomers mainly consisting of styrenes and divinyl monomers as crosslinking agent while using divinylbiphenyl and divinylbenzene mainly as said divinyl monomers and controlling the molar ratio of divinylbiphenyl to divinylbenzene at 10/0-2/8. The cation exchange resin to be used as catalyst in the condensation reaction shows a long life, maintains the production of bisphenol A over a long period of time, possesses high strength and is useful for economical and advantageous production of bisphenol A.
    Type: Grant
    Filed: November 29, 2000
    Date of Patent: December 11, 2001
    Assignee: Nippon Steel Chemical Co., Ltd.
    Inventors: Katsuhiko Sakura, Shingo Ueda, Genki Takeuchi, Shyouta Shirasaka, Toshikazu Maruyama, Yasuharu Hukuda, Taketoshi Kitoh, Morio Kimura