Granted Patent
Utility
US 4,963,271 · App. 07/238,687
Process for the separation and purification of cellulose ethers and cellulose derivatives
Inventors:
Wilfried Raehse, Willi Wuest, Norbert Kuehne
Patented Case
View Patent ↗
Granted: Oct 16, 1990
Filed: Aug 31, 1988
Inventors
Wilfried Raehse
Willi Wuest
Norbert Kuehne
Assignee (at issue)
Henkel Kommanditgesellschaft auf Aktien
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.