Granted Patent
Utility
US 4,880,441 · App. 07/296,843
Asymmetric gas separation membranes having graded density skins
Inventors:
Robert E. Kesting, Alfred K. Fritzsche, Milton K. Murphy, Alan Handerman, Clint A. Cruse, Raymond F. Malon
Patented Case
View Patent ↗
Granted: Nov 14, 1989
Filed: Jan 12, 1989
Inventors
Robert E. Kesting
Alfred K. Fritzsche
Milton K. Murphy
Alan Handerman
Clint A. Cruse
Raymond F. Malon
Assignee (at issue)
Permea, 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.