Granted Patent
Utility
US 4,465,449 · App. 06/447,352
Coextrusion feedblock for making lightweight, rigid thermoplastic pipe
Inventor:
Robert L. Hornbeck
Patented Case
View Patent ↗
Granted: Aug 14, 1984
Filed: Dec 6, 1982
Inventor
Robert L. Hornbeck
Assignee (at issue)
Borg-Warner Chemicals, 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.