Granted Patent
Utility
US 4,933,397 · App. 07/315,992
Preparation of N-substituted phenyl polybenzimidazole polymers
Inventors:
Michael J. Sansone, Mark S. Kwiatek
Patented Case
View Patent ↗
Granted: Jun 12, 1990
Filed: Feb 27, 1989
Inventors
Michael J. Sansone
Mark S. Kwiatek
Assignee (at issue)
Hoechst Celanese Corporation
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.