Granted Patent
Utility
US 5,073,621 · App. 07/515,999
Removal of group VIII metal catalyst from polymer cements by extraction with aqueous dicarboxylic acid
Inventor:
Raymond C. Tsiang
Patented Case
View Patent ↗
Granted: Dec 17, 1991
Filed: Apr 16, 1990
Inventor
Raymond C. Tsiang
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.