Granted Patent
Utility
US 5,166,439 · App. 07/440,707
Composition containing a mannich base of a partially sulfurized hindered phenol mixture
Inventors:
William Y. Lam, Christian S. Harstick
Patented Case
View Patent ↗
Granted: Nov 24, 1992
Filed: Nov 24, 1989
Inventors
William Y. Lam
Christian S. Harstick
Assignee (at issue)
Ethyl Petroleum Additives, 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.