Process for production of an ethanol solution of the ethyl or butyl half-ester of a copolymer of maleic anhydride and methyl vinyl ether

Granted: Jun 29, 1993 Filed: Mar 16, 1992

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.