Multivalent cation-containing copolymer, process for production thereof and use thereof to treating aqueous dispersions

A multivalent cation containing copolymer, which is water-soluble and in particulate form, wherein the multivalent cation containing copolymer is derived from one or more ethylenically unsaturated acids, the copolymer having the following characteristics:

• (a) an intrinsic viscosity of at least about 3 dl/g when measured in 1 M NaCl solution at 25° C.;
• (b) the copolymer is a reaction product of a monomer mixture comprising an ethylenically unsaturated acid in an amount in the range of from about 5% to about 65% by weight and at least one comonomer selected from the group consisting of acrylamide, methacrylamide and any mixture thereof;
• and
• (c) a residual comonomer content is less than 1000 ppm when the comonomer is an acrylamide,
• wherein the multivalent cation containing copolymer has a gel content measurement of less than 50% gel.