Granted Patent
Utility
US 5,756,691 · App. 08/874,961
Water--insoluble azo colorants based on N-acetoacetyldehydrothiotoluidine
Inventors:
Joachim Weber, Hans Joachim Metz
Patented Case
View Patent ↗
Granted: May 26, 1998
Filed: Jun 13, 1997
Inventors
Joachim Weber
Hans Joachim Metz
Assignee (at issue)
Hoechst GmbH
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.