[Oral Session 2] FUNCTIONAL MECHANISMS OF CATIONIC POLYMERS IN NEUTRAL-ALKALINE PAPER SIZING WITH ROSIN SIZES

Cationic polymers. such as partly aminated poly (N- vinylformamide), copolymer of trimethylaminoethyl acrylate with acrylamide, polyethyleneimine, polyallylamine, and poly (diallyldimethylammonium chloride). were investigated to elucidate their contributions to neutral- alkaline paper sizing with acid rosin sizes. The sizing results indicated that both amounts of aluminium and rosin size retained in paper were increased by the suitable polymer addition, and that the polymers with amide group in part and with lower charge density were more efficient to the sizing of rosin emulsion size. whereas the polymers with higher charge density were effective for rosin soap size. Based on the results of paper sizing with rosin-alum and various polymers. the particle size distribution. and the polyelectrolyte titration of aluminium sulfate-polymer mixture. it was proposed that suitable cationic polymers could form stable complex with rosin size particles through hydrogen bonds 01' ionic bonds and with aluminium by coordination bonds. to prevent from the destructive action of hydroxyl ion so that the good sizing of rosin size - alum can be achieved under neutral- alkaline conditions.