Granted Patent
Utility
US 4,801,634 · App. 07/064,730
Production of pigmentary copper phthalocyanine
Inventors:
Robert Langley, John D. Stewart, Arthur Stark Walls
Patented Case
View Patent ↗
Granted: Jan 31, 1989
Filed: Jun 22, 1987
Inventors
Robert Langley
John D. Stewart
Arthur Stark Walls
Assignee (at issue)
Ciba-Geigy
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.