Granted Patent
Utility
US 4,808,395 · App. 06/943,491
High-quality coloring carbon black and process for its production
Inventors:
Shushichi Yoshimura, Makoto Ishizu, Hiromu Kobayashi, Hozo Yamazaki
Patented Case
View Patent ↗
Granted: Feb 28, 1989
Filed: Dec 19, 1986
Inventors
Shushichi Yoshimura
Makoto Ishizu
Hiromu Kobayashi
Hozo Yamazaki
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.