Granted Patent
Utility
US 4,240,915 · App. 05/924,171
Drilling mud viscosifier
Inventor:
Jacob Block
Patented Case
View Patent ↗
Granted: Dec 23, 1980
Filed: Jul 13, 1978
Inventor
Jacob Block
Assignee (at issue)
W. R. Grace & 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.