Granted Patent
Utility
US 4,973,712 · App. 07/312,788
2-aralkylaminofluorans, their preparation and the use thereof in recording materials
Inventor:
Rudolf Zink
Patented Case
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Granted: Nov 27, 1990
Filed: Feb 21, 1989
Inventor
Rudolf Zink
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.