Granted Patent
Utility
US 4,642,380 · App. 06/535,016
Purification of methacrylamidopropyltrimethylammonium chloride
Inventor:
David R. Livingston
Patented Case
View Patent ↗
Granted: Feb 10, 1987
Filed: Sep 23, 1983
Inventor
David R. Livingston
Assignee (at issue)
Texaco 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.