Granted Patent
Utility
US 6,448,438 · App. 09/493,011
Method for purifying acrylic acid
Inventors:
Shuhei Yada, Masahiko Yamagishi, Kouji Kasamatsu, Yasuyuki Sakakura, Kiyoshi Takahashi
Patented Case
View Patent ↗
Granted: Sep 10, 2002
Filed: Jan 28, 2000
Inventors
Shuhei Yada
Masahiko Yamagishi
Kouji Kasamatsu
Yasuyuki Sakakura
Kiyoshi Takahashi
Assignee (at issue)
MITSUBISHI CHEMICAL CORPORATION
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.