Production of paper filled with precipitated calcium carbonate or slurries thereof

摘要

Filled paper is made by: 1. adding a cationising amount of cationic polymer to a slurry of precipitated calcium carbonate, 2. mixing this slurry into a celulosic suspension and forming a thin stock, 3. adding anionic particulate material to the suspension before or after the slurry, 4. 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.