Granted Patent
Utility
US 4,975,156 · App. 07/347,606
Process for the separation of hydrogen fluoride, 1,1-dichloro-1-fluoroethane and 1-chloro-1,1-difluoroethane from liquid mixtures thereof
Inventor:
John A. Wismer
Patented Case
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Granted: Dec 4, 1990
Filed: May 4, 1989
Inventor
John A. Wismer
Assignee (at issue)
Atochem North America, Inc.
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.