Granted Patent
Utility
US 4,689,403 · App. 06/372,891
Disazo pigment from condensation of carboxylic acid chloride with 2,5-dichloro-1,4-phenylene diamine
Inventor:
Karl Ronco
Patented Case
View Patent ↗
Granted: Aug 25, 1987
Filed: Apr 29, 1982
Inventor
Karl Ronco
Assignee (at issue)
Ciba-Geigy
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.