Patents by Inventor Hansrolf Loeffel

Hansrolf Loeffel 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).

  • Heterocyclic containing disazo compounds
    Patent number: 3931142
    Abstract: Polyazo dyestuffs of the formulaA--N=N--M--D--M'--N=N--A'wherein A and A' each represents a 2(8)-amino-8(2)-hydroxynaphthalene radical further substituted with a sulphonic acid group, M and M' each represents a substituted 1,4- or 1,3-phenylene radical and D represents an organic radical bonded in the manner of an amide to M and M', said dyestuffs containing at least two sulphonic acid groups in the molecule, as well as photographic material containing in at least one layer a polyazo dyestuff of the above formula are described.
    Type: Grant
    Filed: October 23, 1973
    Date of Patent: January 6, 1976
    Assignee: Ciba-Geigy AG
    Inventors: John Lenoir, Paul Tschopp, Hansrolf Loeffel, DE Montmollin: Rene