Bulking and opacifying fillers for paper and paper board

摘要

A method for producing bulking and opacifying kaolin fillers for filling cellulosic products is disclosed. An aqueous slurry of anionically dispersed kaolin particles is formed at 1 to 30 % solids. A low-molecular-weight cationic aggregating agent is then added to the dispersed slurry to selectively aggregate fine and ultra-fine particles. The resultant aggregates are of larger mean particle size than the feed material and contain little or no fine and ultra-fine or colloidal particles. The net charge present on the aggregated particles is lower than that of the feed material. The aggregated structure contains within it a labyrinth of internal voids or pores. These mineral aggregates are then of a suitable size and surface charge to be retained well in a fiber web, and provide added bulk and opacity to the cellulosic products.