Granted Patent
Utility
US 3,939,109 · App. 05/534,230
Polyamic-acids prepared from 3,3,4,4-benzhydrol tetracarboxylic dianhydride
Inventors:
Walter P. Barie, Jr., Anatoli Onopchenko, Johann G. D. Schulz
Patented Case
View Patent ↗
Granted: Feb 17, 1976
Filed: Dec 19, 1974
Inventors
Walter P. Barie, Jr.
Anatoli Onopchenko
Johann G. D. Schulz
Assignee (at issue)
Gulf Research & Development Company
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.