Granted Patent
Utility
US 4,587,283 · App. 06/719,023
Cement slurries for deep holes, with a copolymer content for reducing the water loss
Inventors:
Martin Hille, Wolfgang Friede, Heinz Wittkus, Friedrich Engelhardt, Ulrich Riegel
Patented Case
View Patent ↗
Granted: May 6, 1986
Filed: Apr 3, 1985
Inventors
Martin Hille
Wolfgang Friede
Heinz Wittkus
Friedrich 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.