Patent ID: 7732525

Claim:
A paper or paperboard coating composition comprising (a) a substantially water-soluble amphoteric synthetic (co)polymeric co-binder, having an overall anionic charge, and a weight average molecular weight of about 40,000 to about 2,000,000 Daltons, (b) a pigment, wherein the pigment makes up about 50 to about 90 percent by weight of the total solids weight of the coating composition, (c) a primary binder, wherein the primary binder is selected from the group consisting of latex polymers, styrene butadiene, styrene acrylate lattices, starch or modified starch, polyvinyl acetate, hydrolyzed polyvinyl acetate, polyvinyl acetate-acrylate, ethylene vinyl acetate, polyvinyl alcohol and mixtures thereof and optionally, (d) other coating additives, wherein the (co)polymeric co-binder is formed from ethylenically unsaturated, monomer(s) or macromer(s) selected from the group consisting of i) cationic and anionic or potentially anionic monomer(s) or macromer(s) and optionally nonionic monomer(s) or macromer(s); and iii) zwitterionic or potentially zwitterionic monomer(s) or macromer(s) and anionic or potentially anionic monomer(s) or macromer(s) and optionally nonionic monomer(s) or macromer(s); wherein i,) or iii.) may optionally further comprise a crosslinking agent, wherein the cationic monomer(s) are selected from the group consisting of dialkylaminoalkyl(meth)acrylates quaternary salts, dialkylaminoalkyl(meth)acrylamides quaternary salts, N,N-diallyldialkyl ammonium halides, acid addition salts or quaternary ammonium salts of allyl amines, acid addition salts or quaternary ammonium salts of diallyl amines and cationic vinylpyridines.