Granted Patent
Utility
US 4,847,457 · App. 07/161,374
Methylphosphonic acid amine salt lubricant additives
Inventors:
Hermann O. Wirth, Klaus Muller
Patented Case
View Patent ↗
Granted: Jul 11, 1989
Filed: Feb 22, 1988
Inventors
Hermann O. Wirth
Klaus Muller
Assignee (at issue)
Ciba-Geigy
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.