Azo dyes from 1,3,4-thiadiazol-2-yl and 1,2,4-thiadiazol-5-yl moieties bearing sulfated hydroxyalkoxycarbonyl or N-(hydroxyalkyl)carbamoyl groups on their rings

Granted: Nov 24, 1981 Filed: Dec 5, 1979

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.