Granted Patent
Utility
US 5,210,221 · App. 07/757,160
Crystal of fluoran compound and preparation process of the crystal
Inventors:
Masakatsu Nakatsuka, Atsuo Otsuji, Kiyoharu Hasegawa, Kazuyoshi Kikkawa, Akihiro Yamaguchi
Patented Case
View Patent ↗
Granted: May 11, 1993
Filed: Sep 10, 1991
Inventors
Masakatsu Nakatsuka
Atsuo Otsuji
Kiyoharu Hasegawa
Kazuyoshi Kikkawa
Akihiro Yamaguchi
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.