Patent ID: 6921746

Claim:
A multifunctional polymer comprising polymerized units of (a) an α-acyloxyacrylonitrile, αhaloacrylic acid, αacyloxyacrylic ester, α-hydroxyacrylic acid or a mixture thereof, (b) one or more monoethylenically unsaturated carboxylic acids, (c) one or more vinyl esters of saturated aliphatic monocarboxylic acids, vinyl alcohol or a mixture thereof, (d) optionally, one or more other monoethylenically unsaturated monomers copolymerizable with said monomers (a) to (c), and (e) optionally, one or more crosslinkers comprising at least two ethylenically unsaturated double bonds, wherein the multifunctional polymer has a K value of at least 7 and optionally wherein the monomer units (a) and (c) are partially or completely hydrolyzed.