Granted Patent
Utility
US 4,661,581 · App. 06/656,325
Process for producing aromatic polyether ketones and polythioether ketones
Inventors:
Seiichi Nozawa, Michio Nakata
Patented Case
View Patent ↗
Granted: Apr 28, 1987
Filed: Oct 1, 1984
Inventors
Seiichi Nozawa
Michio Nakata
Assignee (at issue)
Mitsubishi Chemical Industries, Ltd.
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.