Paper sizing agents from micelle-like aggregates of polystyrene-eased cationic copolymers

A series of polystyrene-based cationic copolymers (PSCC) were synthesized b y copolymerization of styrene and the cationic comonomer vinylbenzyl trimet hylammonium chloride. These copolymers can be used as internal paper sizing agents in a broad pH range. The effect of the charge density on the PSCC c olloid properties was investigated. It was found that at room temperature t he PSCC could change from water insoluble to colloidally dispersible and fi nally to fully water soluble as the charge density was increased. Based on the understanding of their colloid behavior, PSCCs were applied as internal sizing agents for paper. The results showed that the hydrophobicity of han dsheets could be significantly improved by PSCCs and the sizing performance was a function of copolymer addition, charge density, particle size, dryin g temperature, and pH conditions. The present study indicated some potentia l advantages of PSCC copolymers as internal sizes. PSCC can be self-retaine d on the fiber surface, no hydrolysis occurs during the storage and applica tion, and no sizing reversion occurs. (C) 2000 John Wiley & Sons, Inc.