Patents by Inventor Wilfried G. Holtje

Wilfried G. Holtje 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 2-anilinoacridone
    Patent number: 4544746
    Abstract: A process is disclosed wherein 2,5-di(phenylamino) terephthalic acid is half-cyclized by dissolving it in a mixture of polyphosphoric acid and phosphoric acid and heating at 100.degree.-120.degree. C. to form 2-(phenyl)amino-3-carboxy-9(10H)acridone (ACA). The ACA is decarboxylated to form 2-(phenyl)amino-9(10H)acridone, also known as 2-anilinoacridone, by dissolving it in tetramethylene sulfone and heating in the presence of a basic cupric carbonate catalyst.
    Type: Grant
    Filed: May 17, 1982
    Date of Patent: October 1, 1985
    Assignee: Ciba-Geigy Corporation
    Inventor: Wilfried G. Holtje
  • Light stable quinacridonequinone pigments
    Patent number: 4426231
    Abstract: Quinacridonequinone pigments photostabilized with from 2.5 to 20 wt. % Mn(OH).sub.2 are disclosed. The Mn(OH).sub.2 is precipitated on the pigment from an aqueous solution of a divalent manganese salt by either adding a base or adding urea to the salt solution and heating.
    Type: Grant
    Filed: August 12, 1982
    Date of Patent: January 17, 1984
    Assignee: E. I. Du Pont de Nemours and Company
    Inventor: Wilfried G. Holtje
  • Light stable quinacridonequinone yellow pigment
    Patent number: 4286998
    Abstract: A solid solution of a quinacridonequinone with a stabilizer selected from the group consisting of 2-anilinoacridone, 5,6,7,8-tetrahydro-2-anilinoacridone, 6-anilinoquinolone and 2-aminoacridone of improved lightfastness is provided which displays improved dispersibility while still maintaining a high degree of transparency in automotive finishes when post-treated with a surfactant.
    Type: Grant
    Filed: May 27, 1980
    Date of Patent: September 1, 1981
    Assignee: E. I. DuPont de Nemours and Company
    Inventors: Wilfried G. Holtje, George H. Senkler, Arthur J. Taggi