Method for producing paper and agent for improving yield

摘要

The objective of the present invention is to provide a papermaking method that can enhance the retention in the papermaking steps. This invention provides a method including making paper by adding to pulp slurry a silica sol which is prepared through a reaction between an aqueous solution of sodium silicate and a mineral acid, and which has, under a SiO2 concentration from 15 to 50 g/L wherein the value of the concentration is shown by [C], a viscosity from 0.12x[C] mPa.s to 15 mPa.s measured at 25° C, and a cationic component and/or an amphoteric component.