| abstract |
(57) [Summary] [Problem] Even if the mixing ratio of waste paper or mechanical pulp increases, The purpose is to develop a papermaking method that can maintain a high yield. For this reason, using a specific amphoteric polymer substance, a floc that is resistant to various shearing forces in the papermaking process due to the progress of closed papermaking and the like and has an appropriate strength that does not cause paper collapse after papermaking. A yield improving agent to be produced is developed, and a yield improving method using the same is provided. SOLUTION: A high amphoteric water-solubility consisting of 5 to 95 mol% of two kinds selected from specific cationic monomers, 5 to 50 mol% of anionic monomer and 0 to 90 non-ionic monomer. It can be achieved by adding the molecules to the papermaking raw material before papermaking, processing the paper, and then papermaking. It can also be achieved by using in combination with an anionic water-soluble polymer. |