Granted Patent
Utility
US 5,510,436 · App. 08/260,037
Water-soluble copolymers useful in drilling fluids
Inventors:
Martin Hille, Heinz Wittkus, Jürgen TONHAUSER, Fritz Engelhardt, Ulrich Riegel
Patented Case
View Patent ↗
Granted: Apr 23, 1996
Filed: Jun 15, 1994
Inventors
Martin Hille
Heinz Wittkus
Jürgen TONHAUSER
Fritz Engelhardt
Ulrich Riegel
Assignee (at issue)
Hoechst GmbH
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.