A paper coating composition comprising an aqueous dispersion of polymer particles having an average particle size in the range of 80 nm to 500 nm; as measured according to the method in the description; wherein the polymer particles comprise a first phase having a T g of greater than 50 °C and a second phase having a T g of less than 35 °C; wherein the weight-to-weight ratio of the first phase to the second phase is in the range of from 5:95 to 50:50; wherein the first phase comprises: a) from 90 to 99 weight percent structural units of a first ethylenically unsaturated nonionic monomer; and b) from 1 to 10 weight percent structural units of a first carboxylic acid monomer; based on the weight of structural units of the first ethylenically unsaturated nonionic monomer and the first carboxylic acid monomer; wherein the second phase comprises: a) from 90 to 98 weight percent structural units of a second nonionic ethylenically unsaturated monomer; and b) from 2 to 10 weight percent structural units of a second carboxylic acid monomer, based on the weight of the second nonionic ethylenically unsaturated monomer and the second carboxylic acid monomer; wherein the polymer particles comprise from 35 to 50 weight percent of the paper coating composition; wherein the paper coating composition further comprises from 0.05 to 5 weight percent Zn ++ or Zr ++++ ions based on the weight of the polymer particles, wherein the mole:mole ratio of the structural units of the carboxylic acid monomers to Zn ++ ions is in the range of from 7:1 to 2:1, and the mole:mole ratio of the structural units of the carboxylic acid monomers to Zr ++++ ions is in the range of from 3.5:1 to 1:1. an average particle size in the range of 80 nm to 500 nm; as measured according to the method in the description; wherein the polymer particles comprise a first phase having a T g of greater than 50 °C and a second phase having a T g of less than 35 °C; wherein the weight-to-weight ratio of the first phase to the second phase is in the range of from 5:95 to 50:50; wherein the first phase comprises: a) from 90 to 99 weight percent structural units of a first ethylenically unsaturated nonionic monomer; and b) from 1 to 10 weight percent structural units of a first carboxylic acid monomer; based on the weight of structural units of the first ethylenically unsaturated nonionic monomer and the first carboxylic acid monomer; a) from 90 to 99 weight percent structural units of a first ethylenically unsaturated nonionic monomer; and b) from 1 to 10 weight percent structural units of a first carboxylic acid monomer; based on the weight of structural units of the first ethylenically unsaturated nonionic monomer and the first carboxylic acid monomer; wherein the second phase comprises: a) from 90 to 98 weight percent structural units of a second nonionic ethylenically unsaturated monomer; and b) from 2 to 10 weight percent structural units of a second carboxylic acid monomer, based on the weight of the second nonionic ethylenically unsaturated monomer and the second carboxylic acid monomer; a) from 90 to 98 weight percent structural units of a second nonionic ethylenically unsaturated monomer; and b) from 2 to 10 weight percent structural units of a second carboxylic acid monomer, based on the weight of the second nonionic ethylenically unsaturated monomer and the second carboxylic acid monomer; wherein the polymer particles comprise from 35 to 50 weight percent of the paper coating composition; wherein the paper coating composition further comprises from 0.05 to 5 weight percent Zn ++ or Zr ++++ ions based on the weight of the polymer particles, wherein the mole:mole ratio of the structural units of the carboxylic acid monomers to Zn ++ ions is in the range of from 7:1 to 2:1, and the mole:mole ratio of the structural units of the carboxylic acid monomers to Zr ++++ ions is in the range of from 3.5:1 to 1:1.