Vinylformamide-based cationic polymers as retention aids in alkaline papermaking

With papermaking processes shifting from acidic to alkaline conditions, researchers are studying methods to improve sizing under alkaline conditions, including the use of novel retention aids. In this study, vinylformamide-based cationic polymers were synthesized and were characterized with GPC and polyelectrolyte titration. The polymers were then used as retention aids for rosin size under alkaline conditions. The polymers showed great potential as retention aids, with the performance of each being relative to the chemical structure of its cationic portion and its molecular weight. Furthermore, the characterization of the retention behavior by SEM and ESCA revealed that the polymer molecules could physically form a special structure with rosin size particles so that the rosin size particles would still be stable under alkaline conditions. Application: Paper mills can use the new cationic polymers as effective retention aids with conventional rosin sizes in alkaline papermaking.