Patent ID: 8491753

Claim:
A method of improving retention and drainage in a papermaking process, the method comprising adding to a papermaking furnish, in any order: (a) an effective amount of a microparticle; (b) an effective amount of a promoter, wherein the promoter includes a modified diallyl-N,N-disubstituted ammonium halide polymer which is composed of more than 30 mole % and less than 70 mole % diallyldimethylammonium chloride monomer and between less than 70 mole % and more than 30 mole % acrylamide monomer, the modified diallyl-N,N-disubstituted ammonium halide polymer has an RSV of between 0.2 and 12 dL/g and a charge density of less than 7 miliequivalents/g polymer, and (c) an effective amount of a flocculent, wherein the flocculent includes one or more high molecular weight, water-soluble cationic, anionic, nonionic, zwitterionic, or amphoteric polymers having an RSV of at least about 3 dL/g wherein the combination of all three of (a), (b), and (c) increase the retention properties of a papermaking furnish beyond the performance of ionic, cross-linked polymeric microbeads having a diameter of less than about 1000 nm combined with a high molecular weight polysaccharide in the furnish, and wherein the modified diallyl-N,N-disubstituted ammonium halide polymer has a cationic charge of about 1 to about 99 mole percent and was prepared according to the steps of: (i) preparing an aqueous solution comprising one or more diallyl-N,N-disubstituted ammonium halide monomers and about 35 to about 85 percent of the total acrylamide monomer; (ii) initiating polymerization of the monomers; (iii) allowing the polymerization to proceed to at least about 5 percent diallyl-N,N-disubstituted ammonium halide monomer conversion and at least about 20 percent acrylamide monomer conversion; and (iv) adding the remaining acrylamide monomer and allowing the polymerization to proceed to the desired endpoint.