Patents by Inventor Peter Artur Wriede

Peter Artur Wriede 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 quinacridonequinone by oxidation of dihydroquinacridone
    Patent number: 4025518
    Abstract: Improved process for preparing quinacridonequinone by the oxidation of dihydroquinacridone in aqueous acidic medium using an alkali metal chlorate as the oxidizing agent in the presence of vanadium pentoxide and, optionally, passing air through the aqueous acidic medium during the oxidation. The quinacridonequinone so prepared exhibits superior color quality and is useful as a pigment in a wide variety of applications.
    Type: Grant
    Filed: February 20, 1976
    Date of Patent: May 24, 1977
    Assignee: E. I. Du Pont de Nemours and Company
    Inventor: Peter Artur Wriede