Patent attributes
The invention provides a paper quality improver for papermaking that allows improvement in the bulky value and the optical properties such as brightness and opacity as well as in the paper strength of a sheet obtained by papermaking a pulp material. The paper quality improver for papermaking is a paper quality improver for papermaking containing a copolymer (A) having a constituent unit derived from at least one nonionic monomer having a solubility parameter of 20.5 (MPa)1/2 or less and a constituent unit derived from at least one anionic or cationic monomer and a surfactant (B) at a certain ratio, the quality improver providing at least one paper quality improving effect of: (i) standard improved bulky value: 0.02 g/cm or more; (ii) standard improved opacity: 1.0 point or more; and (iii) standard improved brightness: 0.5 point or more.
