Granted Patent
Utility
US 4,540,560 · App. 06/543,684
Carbon blacks
Inventors:
E. Webb Henderson, Mark L. Gravley
Patented Case
View Patent ↗
Granted: Sep 10, 1985
Filed: Oct 20, 1983
Inventors
E. Webb Henderson
Mark L. Gravley
Assignee (at issue)
Phillips Petroleum 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.