Granted Patent
Utility
US 4,351,957 · App. 06/053,378
Process for preparing diaminodiphenyl-alkanes
Inventor:
Kwok K. Sun
Patented Case
View Patent ↗
Granted: Sep 28, 1982
Filed: Jun 29, 1979
Inventor
Kwok K. Sun
Assignee (at issue)
The Upjohn Co.
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.