Granted Patent
Utility
US 5,218,053 · App. 07/880,280
Polymers having stable anhydride rings
Inventor:
Donn A. DuBois
Patented Case
View Patent ↗
Granted: Jun 8, 1993
Filed: May 8, 1992
Inventor
Donn A. DuBois
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.