Production of filled paper

摘要

Filled paper is made by adding a cationising amount of cationic polymer to a slurry of precipitated calcium carbonate, mixing this slurry into a cellulosic suspension and forming a thin stock, adding anionic particulate material to the suspension before or after the slurry, mixing a polymeric retention aid into the thin stock which includes the precipitated calcium carbonate and the anionic particulate material, draining the thin stock on a screen to form a sheet and drying the sheet. A suitable slurry for this purpose is a slurry of 5 to 70% by weight precipitated calcium carbonate and cationic polymer selected from 0.1 to 1% cationic starch and 0.01 to 0.3% of a high charge density, relatively low molecular weight, cationic polymer.