Granted Patent
Utility
US 5,159,021 · App. 07/284,186
Process for producing polypropylene and stretched polypropylene film
Inventors:
Mamoru Kioka, Masaya Yamada, Masanobu Ishiyama, Masao Nakano, Akinori Toyota
Patented Case
View Patent ↗
Granted: Oct 27, 1992
Filed: Dec 14, 1988
Inventors
Mamoru Kioka
Masaya Yamada
Masanobu Ishiyama
Masao Nakano
Akinori Toyota
Assignee (at issue)
Mitsui Petrochemical Industries, Ltd.
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.