Granted Patent
Utility
US 4,808,508 · App. 06/880,770
Negative working color proofing process comprising diazo compound and polyvinyl acetal/polyvinyl alcohol/polyvinyl acetate resin
Inventor:
Stephan J. W. Platzer
Patented Case
View Patent ↗
Granted: Feb 28, 1989
Filed: Jul 1, 1986
Inventor
Stephan J. W. Platzer
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.