Granted Patent
Utility
US 4,940,403 · App. 07/345,566
Dual parison extrusion head for multi-layer blow molding
Inventor:
Michael Hirschberger
Patented Case
View Patent ↗
Granted: Jul 10, 1990
Filed: May 1, 1989
Inventor
Michael Hirschberger
Assignee (at issue)
Hoover Universal, 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.