Patent ID: 7547376

Claim:
A process of producing a pulp sheet, said process comprising: adding a paper quality improver for papermaking to pulp in any step before a papermaking step of forming a paper layer while water in a dilute solution of a pulp material is filtered through a wire while moving thereon; wherein the paper quality improver for papermaking comprises: a copolymer (A) having the following constituent units: 10-34 weight % of nonionic unsaturated monomer, wherein said nonionic saturated monomer is tertiary-octyl acrylamide (t-OAAm); 17-23 weight % of an anionic or cationic monomer, wherein said anionic or cationic monomer is a quaternary ammonium salt from dimethylaminopropyl acrylamide and methyl chloride (DMAPAA-Q) or a quaternary ammonium salt from dimethylaminoethyl methacrylate and diethyl sulfate (MOEDES); and 47-67 weight % of a nonionic unsaturated monomer of acrylamide (AAm), and a surfactant (B) at an (A)/(B) ratio in the range of 85/15 to 15/85 (weight ratio), wherein a mixture of the copolymer (A) and the surfactant (B) is prepared by adding surfactant (B) to an aqueous solution of copolymer (A), wherein the paper quality improver provides at least one paper quality improving effect of the following (i), (ii), and (iii): (i) standard improved bulky value: 0.02 g/cm 3 or more; (ii) standard improved opacity: 1.0 point or more; and (iii) standard improved brightness: 0.5 point or more; wherein the surfactant (B) is a water-soluble alcohol alkylene oxide adduct containing an alkylene oxide group having 2 to 4 carbons in an average amount of 5 to less than 150 moles per 1 mole of the alcohol; and wherein the paper quality improver provides a paper quality improving effect of a standard improved ratio in burst index of -502 or more.