Granted Patent
Utility
US 4,255,376 · App. 06/044,805
Solvent stretch process for preparing microporous films from precursor films of controlled crystalline structure
Inventor:
John W. Soehngen
Patented Case
View Patent ↗
Granted: Mar 10, 1981
Filed: Jun 1, 1979
Inventor
John W. Soehngen
Assignee (at issue)
Celanese GmbH
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.