Patents by Inventor Rudolf Stengel

Rudolf Stengel 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).

  • Fluorescent marking liquid
    Patent number: 5084327
    Abstract: A new fluorescent aqueous marking liquid is described, which contains 0.20 to 2.0 % by weight of cumarin C.J. Basic Yellow 40 dye. The liquid is buffered to a pH value of from 3 to 5; it contains an acrylic resin dispersion at a pH of 3 to 5 with a particle agglomerate of 35 to 150 nm. The liquid does not act on a third dye, especially triphenylmethane dye, which is used frequently in carbon paper and is used also on smooth surfaces such as glass plastic foil or glazing paper.
    Type: Grant
    Filed: December 18, 1989
    Date of Patent: January 28, 1992
    Assignee: Faber-Castell
    Inventor: Rudolf Stengel