| 摘要 |
A novel retention aid is provided, which can realizes not only high retention but also excellent paper formation and is easy to use, in various papermaking processes. A composition for improving retention is provided, which comprises (A) a cationic water-soluble polymer and (B) an amphoteric water-soluble polymer. The component (A) preferably is a copolymer having a cation equivalent of 0.05 to 4.00 meq/g or one having a 0.5% salted viscosity of 30 to 200 mPa.s. The component (B) preferably is either a copolymer comprising a cationic radical-polymerizable monomer unit, an anionic radical-polymerizable monomer unit, and a nonionic radical-polymerizable monomer unit, or an amphoteric water-soluble polymer obtained by polymerizing a cationic radical-polymerizable monomer with an anionic radical-polymerizable monomer in the presence of a polysaccharide. From the standpoint of attaining excellent formation, the component (B) preferably has a molar proportion of the cationic radical-polymerizable monomer unit to the anionic radical-polymerizable monomer unit (hereinafter referred to as Ca/An) satisfying Ca/An<1.2.
|
