Granted Patent
Utility
US 4,889,747 · App. 07/317,714
Hydrophobic expanded perlite compositions and process for preparing the same
Inventor:
Michael E. Wilson
Patented Case
View Patent ↗
Granted: Dec 26, 1989
Filed: Mar 1, 1989
Inventor
Michael E. Wilson
Assignee (at issue)
PCR, Inc.
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.