Granted Patent
Utility
US 4,970,001 · App. 07/348,339
Use of chitosan to improve membrane filter performance
Inventor:
John Sheehan
Patented Case
View Patent ↗
Granted: Nov 13, 1990
Filed: May 5, 1989
Inventor
John Sheehan
Assignee (at issue)
W.R. Grace & Co. Conn.
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.