Granted Patent
Utility
US 4,277,398 · App. 06/064,660
Magenta-masked color azopyrazolinone couplers
Inventor:
Brian R. D. Whitear
Patented Case
View Patent ↗
Granted: Jul 7, 1981
Filed: Aug 8, 1979
Inventor
Brian R. D. Whitear
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.