Granted Patent
Utility
US 5,147,646 · App. 07/759,623
Hydrogel containing envelopes
Inventor:
Neil B. Graham
Patented Case
View Patent ↗
Granted: Sep 15, 1992
Filed: Sep 16, 1991
Inventor
Neil B. Graham
Assignee (at issue)
NATIONAL RESEARCH DEVELOPMENT CORPORATION
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.