Granted Patent
Utility
US 4,675,389 · App. 06/617,451
(2-alkoxy-4-sulfonyl-5-alkylphenyl)azo-1-hydroxynaphthalene sulfonic acids
Inventors:
Wayne Lee Cook, Robert P. Huth
Patented Case
View Patent ↗
Granted: Jun 23, 1987
Filed: Jun 5, 1984
Inventors
Wayne Lee Cook
Robert P. Huth
Assignee (at issue)
Hilton Davis Chemical Co.
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.