Granted Patent
Utility
US 4,992,556 · App. 07/314,021
Process for the preparation of indigo compounds
Inventors:
Usaji Takaki, Hiroharu Suzuki, Yoshihiro Yamamoto, Shinobu Aoki, Isao Hara
Patented Case
View Patent ↗
Granted: Feb 12, 1991
Filed: Feb 23, 1989
Inventors
Usaji Takaki
Hiroharu Suzuki
Yoshihiro Yamamoto
Shinobu Aoki
Isao Hara
Assignee (at issue)
Mitsui Toatsu Chemicals, Incorporated
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.