Granted Patent
Utility
US 5,196,521 · App. 07/719,868
Azo dyes prepared using 2-alkylamino-3-cyano-4,6-diaminopyridines as coupling components
Inventors:
Visvanathan Ramanathan, Angelo D. Casa
Patented Case
View Patent ↗
Granted: Mar 23, 1993
Filed: Jun 24, 1991
Inventors
Visvanathan Ramanathan
Angelo D. Casa
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.