Granted Patent
Utility
US 4,308,352 · App. 06/257,466
Process of extruding polysulfone foam
Inventor:
Dennis A. Knaus
Patented Case
View Patent ↗
Granted: Dec 29, 1981
Filed: Apr 24, 1981
Inventor
Dennis A. Knaus
Assignee (at issue)
Packaging Industries Group, Inc.
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.