Granted Patent
Utility
US 4,952,731 · App. 07/232,011
Process for producing diphenylamines or N,N'-diphenyl-phenylenediamines
Inventors:
Teruyuki Nagata, Akihiro Tamaki, Nobuyuki Kajimoto, Masaru Wada
Patented Case
View Patent ↗
Granted: Aug 28, 1990
Filed: Aug 15, 1988
Inventors
Teruyuki Nagata
Akihiro Tamaki
Nobuyuki Kajimoto
Masaru Wada
Assignee (at issue)
Mitsui Toatsu Chemicals, Incorporated
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.