Process for making ethanol solutions of alkyl half-esters of copolymers of maleic anhydride and a C.sub.1 -C.sub.4 alkyl vinyl ether

Granted: Nov 12, 1991 Filed: Aug 30, 1990

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.