"Sulfo group-containing monoazo compounds having an unsubstituted or substituted 4-(benzothiazol-2'-yl)phenyl or 4-(6'-benzothiazol-2""yl)-benzothiazol-2'-yl)phenyldiazo component radical and a 6-hydroxypyrid-2-one coupling component radical"

Granted: Oct 31, 1989 Filed: Mar 31, 1988

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.