Patents by Inventor Constanze Prengel

Constanze Prengel 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).

  • Platelet-like substrates
    Patent number: 5407746
    Abstract: The application relates to deagglomerated and readily dispersible platelet-like substrates with a high degree of softness, which are characterized by a content of 0.5-20% by weight of spherical particles having a small diameter in comparison with the platelet-like substrate, and to a process for their preparation and their use.
    Type: Grant
    Filed: September 28, 1993
    Date of Patent: April 18, 1995
    Assignee: Merck Patent Gesellschaft Mit Beshrankter Haftung
    Inventors: Constanze Prengel, Johann Dietz, Angelika Thurn-Muller
  • Iron oxide pigments
    Patent number: 5354374
    Abstract: The invention relates to iron oxide pigments based on silica, zirconium dioxide and/or titanium dioxide particles coated with iron oxide, the iron oxide content being more than 350% by weight, relative to the weight of the silica, zirconium dioxide and/or titanium dioxide particles.
    Type: Grant
    Filed: November 16, 1992
    Date of Patent: October 11, 1994
    Assignee: Merck Patent Gesellschaft mit beschrankter Haftung
    Inventor: Constanze Prengel
  • Conductive flaky pigments
    Patent number: 5322561
    Abstract: The invention relates to conductive flaky pigments for which a flaky substrate has been coated with an electrically conductive layer, characterized in that the conductive layer comprises a metal oxide pigment layer which is interspersed with carbon black particles and which has at the same time been doped with additional metal oxide particles.
    Type: Grant
    Filed: December 4, 1992
    Date of Patent: June 21, 1994
    Assignee: Merck Patent Gesellschaft mit Beschrankter Haftung
    Inventors: Constanze Prengel, Klaus Bernhardt
  • Interference pigments
    Patent number: 5302199
    Abstract: The invention is interference pigments having improved covering power and high luster based on platelet-shaped substrates which, if desired, are coated with one or more films comprising one or more metal oxides and are obtainable by adding an aqueous carbon black dispersion and a solution of one or more metal salts to an aqueous suspension of the substrate at a pH suitable for hydrolysis of a film comprising the metal oxide(s) or hydroxide(s) and containing carbon black, in which the product obtained, after being separated off and, if desired, after washing and drying, is ignited at 700.degree.-900.degree. C. in an oxygen-containing atmosphere, during which carbon oxides escape.
    Type: Grant
    Filed: November 16, 1992
    Date of Patent: April 12, 1994
    Assignee: Merck Patent Gesellschaft mit beschrankter Haftung
    Inventors: Constanze Prengel, Klaus Bernhardt
  • Materials coated with plate-like pigments
    Patent number: 5223360
    Abstract: Materials coated with plate-like pigments and characterized in that the coating shows structuring in defined areas due to a difference in the orientation of the pigment particles are highly suitable in the area of general security printing.
    Type: Grant
    Filed: November 15, 1990
    Date of Patent: June 29, 1993
    Assignee: Merck Patent Gesellschaft mit beschrankter Haftung
    Inventors: Constanze Prengel, Klaus-Dieter Franz, Hartmut Hartner, Manfred Kieser, Axel von Daacke, Klaus Bernhardt