Granted Patent
Utility
US 5,164,475 · App. 07/473,071
Porous substrates with a high concentration of amine groups
Inventor:
Robert Clayton Wheland
Patented Case
View Patent ↗
Granted: Nov 17, 1992
Filed: Jan 31, 1990
Inventor
Robert Clayton Wheland
Assignee (at issue)
The DuPont Merck Pharmaceutical Company
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.