Patents by Inventor Kerstin Ruhnau

Kerstin Ruhnau 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 the production of purple pigments
    Patent number: 5707436
    Abstract: Prior art production of purple pigments based on colloidal gold on stovable/sinterable/fireable support material involves the reduction of a gold compound in the presence of a chemical reducing agent.Purple pigments may be produced more simply according to the invention by intimately mixing and/or grinding the support material and the gold compound in dry form or by bringing an aqueous solution or suspension of a gold compound and a support material into contact and then thermally treating the mixture at a temperature above the decomposition temperature of the gold compound and below the sintering temperature of the support material, wherein the gold compound is converted into colloidal gold.
    Type: Grant
    Filed: March 29, 1995
    Date of Patent: January 13, 1998
    Assignee: Cerdec Aktiengesellschaft Keramische Farben
    Inventors: Klaus-Dieter Fritsche, Bernd Dorbath, Norbert Giesecke, Kerstin Ruhnau