Abstract
Today's paper industry tries to use greater amount of high yield pulp and recycled fiber and to close mill water system, which results in higher fines content and buildup of organic and inorganic contaminants in white water system. Researches are being focused to develop chemical additives that provide good retention and drainage in a closed papermaking system. A microparticle retention system consisted of cationic guar gum and anionic colloidal silica so has been developed to meet the requirements for improving machine speed and product quality. The objective of this investigation was to determine the effects of the degree of cationic guar gums, charge density and structure of anionic colloidal silica sols, and the degree of system closure on the performances of this microparticle retention system. Cationic guar gums and anionic colloidal silica sols with higher charge densities showed better retention performance. Particularly, wider maximum in retention was obtained when structure colloidal silica was used suggesting as mechanism of microparticle bridging is functioning in this system.