Toners and developers containing quaternary ammonium 3,5-di-tertiary-alkyl-4-hydroxybezenesulfonate salts as charge-control agents

Granted: Feb 13, 1996 Filed: Dec 21, 1994

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.