Granted Patent
Utility
US 4,650,882 · App. 06/674,317
Dyes having two 5-membered lactone rings fused to a central cyclohexa-1.4-diene nucleus
Inventors:
Ronald W. Kenyon, Derek Thorp
Patented Case
View Patent ↗
Granted: Mar 17, 1987
Filed: Nov 23, 1984
Inventors
Ronald W. Kenyon
Derek Thorp
Assignee (at issue)
IMPERIAL CHEMICAL INDUSTRIES LIMITED
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.