Granted Patent
Utility
US 5,663,258 · App. 08/603,668
Strongly swellable, moderately crosslinked copolymers of vinylpyrrolidone and vinyl acetate
Inventors:
Yuanzhen Zhong, Philip F. Wolf
Patented Case
View Patent ↗
Granted: Sep 2, 1997
Filed: Feb 20, 1996
Inventors
Yuanzhen Zhong
Philip F. Wolf
Assignee (at issue)
ISP INVESTMENTS LLC
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.