Granted Patent
Utility
US 4,879,412 · App. 06/835,737
Purification process of methacrylic acid
Inventors:
Kozo Iwasaki, Morimasa Kuragano, Minoru Koshibe, Yoshihiro Sezaki, Katsuji Yoguchi, Yoshio Koyama
Patented Case
View Patent ↗
Granted: Nov 7, 1989
Filed: Mar 3, 1986
Inventors
Kozo Iwasaki
Morimasa Kuragano
Minoru Koshibe
Yoshihiro Sezaki
Katsuji Yoguchi
Yoshio Koyama
Assignees (at issue)
Mitsui Toatsu Chemicals, Incorporated
Kyowa Gas Chemical Industry Co., 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.