Granted Patent
Utility
US 4,306,031 · App. 06/174,566
Weakly acidic cation exchange resin and process for producing same
Inventors:
Takaharu Itagaki, Hidenaga Ouchi
Patented Case
View Patent ↗
Granted: Dec 15, 1981
Filed: Aug 4, 1980
Inventors
Takaharu Itagaki
Hidenaga Ouchi
Assignee (at issue)
Mitsubishi Chemical 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.