Granted Patent
Utility
US 4,990,189 · App. 07/364,052
Iron oxide pigments, a process for their preparation and their use
Inventors:
Jurgen Wiese, Axel Westerhaus, Jurgen Scharschmidt, Gunter Buxbaum
Patented Case
View Patent ↗
Granted: Feb 5, 1991
Filed: Jun 8, 1989
Inventors
Jurgen Wiese
Axel Westerhaus
Jurgen Scharschmidt
Gunter Buxbaum
Assignee (at issue)
Bayer Aktiengesellschaft
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.