Granted Patent
Utility
US 4,323,505 · App. 06/163,660
Polyalkylhydroxychromene and process for preparing the same
Inventors:
Isao Hashimoto, Hirohiko Nambu
Patented Case
View Patent ↗
Granted: Apr 6, 1982
Filed: Jun 27, 1980
Inventors
Isao Hashimoto
Hirohiko Nambu
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.