Granted Patent
Utility
US 3,994,110 · App. 05/566,958
Three hour fire resistant door, panel or building element, and method of manufacturing the same
Inventor:
Leonard A. Ropella
Patented Case
View Patent ↗
Granted: Nov 30, 1976
Filed: Apr 10, 1975
Inventor
Leonard A. Ropella
Assignee (at issue)
Champion International Corporation Limited
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.