!PST Technical Paper Series Number 805 Paper Sizing Agents from Micelle-Like Aggregates of Polystyrene-Based Cationic Copolymers

A series of polystyrene-based cationic copolymers (PSCC) were synthesized by copolymerization of styrene and cationic comonomer vinylbenzyl trimethylammonium chloride (VBTMAC). These copolymers can be used as internal paper sizing agents in a broad pH range. The effect of charge density on the PSCC colloid properties was investigated. It was found that at room temperature the PSCC could change from waterinsoluble to colloidally dispersible and finally to fully water-soluble as the charge density was increased. Based on the understanding of its colloid behavior, PSCCs were applied as paper internal sizing agents. The results showed that the hydrophobicity of handsheets could be significantly improved by PSCC and the sizing performance was the function of copolymer addition, charge density, particle size, drying temperature, as well as pH conditions. The present study indicated some potential advantages of PSCC copolymers as internal sizes. PSCC can be self-retained on the fiber surface, no hydrolysis occurs during the storage and application, and no sizing reversion occurs.