Granted Patent
Utility
US 5,059,721 · App. 07/560,956
Process for preparing a bisphenol
Inventors:
Joseph Broun Powell, Zaida Diaz
Patented Case
View Patent ↗
Granted: Oct 22, 1991
Filed: Jul 31, 1990
Inventors
Joseph Broun Powell
Zaida Diaz
Assignee (at issue)
SHELL OIL COMPANY
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.