Granted Patent
Utility
US 5,229,515 · App. 07/712,016
Process for preparing modified .beta.-quinacridone pigment
Inventors:
Johannes Pfenninger, Walter Zukowski, Fridolin Babler, Edward E. Jaffe
Patented Case
View Patent ↗
Granted: Jul 20, 1993
Filed: Jun 7, 1991
Inventors
Johannes Pfenninger
Walter Zukowski
Fridolin Babler
Edward E. Jaffe
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.