Granted Patent
Utility
US 4,766,236 · App. 07/068,584
Purification of diphenyl phthalates
Inventors:
A. Lee Stautzenberger, Ellen A. Langford
Patented Case
View Patent ↗
Granted: Aug 23, 1988
Filed: Jun 30, 1987
Inventors
A. Lee Stautzenberger
Ellen A. Langford
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.