Patents by Inventor Takasi Okawa

Takasi Okawa 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 maleic anhydride
    Patent number: 5026876
    Abstract: Crude maleic anhydride produced by catalytic oxidation is distilled and then n-propyl gallate, cuprous chloride and zinc chloride are added thereto.Alternatively, crude maleic anhydride is distilled in the presence of tridecyl phosphite. Further, these procedures can be used in combination. Thermal stability and color stability of the maleic anhydride is improved.
    Type: Grant
    Filed: January 19, 1990
    Date of Patent: June 25, 1991
    Assignee: Mitsui Toatsu Chemicals, Inc.
    Inventors: Harusige Sugawara, Takasi Okawa