Granted Patent
Utility
US 4,725,690 · App. 06/876,421
Perylene-3,4,9,10-tetracarboxylic acid diimide dye
Inventor:
Fritz Graser
Patented Case
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Granted: Feb 16, 1988
Filed: Jun 20, 1986
Inventor
Fritz Graser
Assignee (at issue)
BASF SE
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.