Granted Patent
Utility
US 6,214,488 · App. 08/944,667
Polymer electrolyte membrane and process for the production thereof
Inventors:
Freddy Helmer-Metzmann, Frank Osan, Arnold Schneller, Helmut Ritter, Konstantin Ledjeff, Roland Nolte, Ralf Thorwirth
Patented Case
View Patent ↗
Granted: Apr 10, 2001
Filed: Oct 6, 1997
Inventors
Freddy Helmer-Metzmann
Frank Osan
Arnold Schneller
Helmut Ritter
Konstantin Ledjeff
Roland Nolte
Ralf Thorwirth
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.