Patents by Inventor Guenter Engelhardt

Guenter Engelhardt 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).

  • Purification of indigo
    Patent number: 5109137
    Abstract: A process for the preparation of purified indigo comprises extracting the aqueous alkaline indoxylate solution arising from the synthesis with an inert water-insoluble solvent in the absence of oxygen before oxidizing the indoxylate solution to give indigo.
    Type: Grant
    Filed: July 15, 1991
    Date of Patent: April 28, 1992
    Assignee: BASF Aktiengesellschaft
    Inventors: Reinhold Kohlhaupt, Manfred Gaeng, Lothar Haas, Guenter Engelhardt, Walter Bieg, Matthias Fankhaenel
  • Purification of indigo
    Patent number: 5075458
    Abstract: A process for the preparation of purified indigo comprises extracting the aqueous alkaline indoxylate solution arising from the synthesis with an inert water-insoluble solvent in the absence of oxygen before oxidizing the indoxylate solution to give indigo.
    Type: Grant
    Filed: April 15, 1991
    Date of Patent: December 24, 1991
    Assignee: BASF Aktiengesellschaft
    Inventors: Reinhold Kohlhaupt, Manfred Gaeng, Lothar Haas, Guenter Engelhardt, Walter Bieg, Matthias Fankhaenel
  • Printing platen
    Patent number: 4881838
    Abstract: A printing platen particularly for matrix printers is comprised of an aluminum or synthetic body carrying a thin layer of a ceramic material, preferably aluminum oxide, titanium oxide, chromium dioxide or a blend thereof. Such a platen is sufficiently frictional and hard for withstanding the impact of high speed print hammers or needles.
    Type: Grant
    Filed: August 12, 1985
    Date of Patent: November 21, 1989
    Assignee: Mannesmann AG
    Inventors: Gerhard Lohrmann, Guenter Engelhardt, Thomas Werner