Granted Patent
Utility
US 4,832,793 · App. 07/161,727
Process for extruding and acid treating clay for improved color development in carbonless copy paper
Inventor:
William Alexander
Patented Case
View Patent ↗
Granted: May 23, 1989
Filed: Feb 29, 1988
Inventor
William Alexander
Assignee (at issue)
American Colloid 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.