Granted Patent
Utility
US 4,349,443 · App. 06/239,079
Viscosifier and fluid loss control system
Inventor:
Jacob Block
Patented Case
View Patent ↗
Granted: Sep 14, 1982
Filed: Feb 27, 1981
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.