Patents by Inventor Hiroyuki Tubota

Hiroyuki Tubota 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 purification of dihydroxydiphenylsulfone
    Patent number: 4933494
    Abstract: Colored dihydroxydiphenylsulfone obtained by a reaction between phenol and sulfuric acid is treated with activated carbon and a hydrotalcite compound in a mixed solvent comprising methanol and water at a weight ratio of from 10/90 to 60/40. According to this process, colored dihydroxydiphenylsulfone can be industrially advantageously purified at a high efficiency.
    Type: Grant
    Filed: January 13, 1989
    Date of Patent: June 12, 1990
    Assignee: Nicca Chemical Co., Ltd.
    Inventors: Hiroyuki Tubota, Hiroshi Kushima, Kazuhiko Sakai, Naoki Yamamoto