Granted Patent
Utility
US 5,281,348 · App. 07/790,323
Use of anionic surfactant/dispersant blends for the deinking of groundwood newsprint
Inventor:
Mary Beth Letscher
Patented Case
View Patent ↗
Granted: Jan 25, 1994
Filed: Nov 12, 1991
Inventor
Mary Beth Letscher
Assignee (at issue)
Betz PaperChem 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.