Granted Patent
Utility
US 4,419,309 · App. 06/373,455
Polystyrene foam extrusion into a foam assisting atmosphere
Inventor:
Charles M. Krutchen
Patented Case
View Patent ↗
Granted: Dec 6, 1983
Filed: Apr 30, 1982
Inventor
Charles M. Krutchen
Assignee (at issue)
Mobil Oil Corporation
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.