Granted Patent
Utility
US 4,997,921 · App. 07/443,122
Substituted phenylazosulfoindole dyes
Inventor:
Rudolf Hurter
Patented Case
View Patent ↗
Granted: Mar 5, 1991
Filed: Nov 30, 1989
Inventor
Rudolf Hurter
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.