AQUEOUS COATING COMPOSITION

An aqueous coating composition contains: (A) a polyacid polymer containing a phosphonate and/or phosphinate functional group, wherein the polyacid polymer has a weight average molecular weight of 2000 to 25000 g/mol and comprises, by weight based on the weight of the polyacid polymer, from 20%to 100%of structural units of an acid monomer, a salt thereof, or mixtures thereof; and from zero to 80%of structural units of an ethylenically unsaturated nonionic monomer; (B) an emulsion polymer comprising, by weight based on the weight of the emulsion polymer, from 0.3%to 2.5%of structural units of an ethylenically unsaturated phosphorous-containing acid monomer, a salt thereof, or mixtures thereof; from zero to 10%of structural units of an additional acid monomer, a salt thereof, or mixtures thereof; and structural units of an ethylenically unsaturated nonionic monomer; (C) from 0.005%to 0.15%, by weight based on the weight of the aqueous coating composition, of a polyethylenimine, a modified polyethylenimine, or mixtures thereof; having a weight average molecular weight of 500 to 50000 grams per mole; and (D) a pigment, an extender, or mixtures thereof; where the coating composition has a pigment volume concentration of 78%to 86%.