Granted Patent
Utility
US 4,940,571 · App. 07/176,582
Method of making large particle size, high purity dense silica
Inventors:
Sophia R. Su, Leo F. Fitzpatrick, Sheryl A. Robillard
Patented Case
View Patent ↗
Granted: Jul 10, 1990
Filed: Apr 1, 1988
Inventors
Sophia R. Su
Leo F. Fitzpatrick
Sheryl A. Robillard
Assignee (at issue)
GTE Laboratories Incorporated
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.