Granted Patent
Utility
US 4,921,652 · App. 07/229,797
Process for producing a porous film
Inventors:
Syoichi Tsuji, Syoichi Ito, Shuji Matsumura, Hisatosi Suzuki, Michiyasu Ito
Patented Case
View Patent ↗
Granted: May 1, 1990
Filed: Aug 8, 1988
Inventors
Syoichi Tsuji
Syoichi Ito
Shuji Matsumura
Hisatosi Suzuki
Michiyasu Ito
Assignee (at issue)
Mitsui Toatsu Chemicals, 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.