Study On Preparation And Application Of Cationic Rosin Sizes

Sizing agents are widely used in papermaking industry to render sized paper resistant to the penetration or wetting of aqueous liquids, and rosin based sizing agents with advantages of resource sustainability and cost effectiveness have always been leading an indispensable and influential position in certain practical applications. Nowadays, development of rosin based sizing agents with suitability to neutral papermaking system is generally catering to the development trend of neutral sizing and papermaking, and such kind of sizing agents are surely to achieve a promising prospect, and cationic dispersed rosin size with such characteristics is mostly preferred for its sizing efficiency and operation simplicity. Additionally, preparation and potential application of rosin based cationic surfactants has always been in the highlight in recent years. In our work, novel rosin based cationic surfactants were prepared using epichlorohydrin, triethylamine and rosin as reactants, and application of such surfactants in the preparation of cationic dispersed rosin size were intensively investigated. Also, copolymer based dispersant was applied to improve the quality of the dispersed rosin size combined with rosin based cationic surfactants. The experiments aimed at sizing efficiency improvement were conducted in our work, with the optimum application condition optimized considering many influencing factors. From our experimental work, several conclusions can be drawn as follows:(1) Rosin based cationic surfactants prepared from epichlorohydrin, triethylamine and rosin can be used as effective emulsifiers for rosin emulsification, and the optimum mass ratio, reaction temperature and reaction time are 1.2:1:1,70～100℃ and 4h, respectively.(2) The copolymer based cationic dispersant prepared principally from styrene, acrylic ester and cationic monomers can be an effective emulsifier for rosin emulsification. When combined with surfactants to form a system for rosin emulsification, the dispersant with the optimum dosage in the range of 10%～ 12% can reduce the dosage of surfactants and further improve the emulsion stability.(3) Cationic dispersed rosin size prepared using the mixed system comprising the rosin based cationic surfactants and the dispersant according to the so called inversion mechanism can exhibit preferably good sizing efficiency. In the specific preparation process, emulsifying temperature is the key factor influencing the quality of finished product in addition to the emulsifying system.(4) Experimental results show that, when the cationic dispersed rosin sizewas used as a sizing agent for wheat straw pulps, the optimum size and alum dosage are 0.5% ~ 1.0% and 1.5 ~2%, respectively, and CRS-2-9 and CRS-3-13 can give good sizing efficiency in the pH range of 7~7.5.(5) The investigations in our work for optimizing the sizing effect of the cationic dispersed rosin size with retention aid systems show that anionic polyacrylamide /cationic starch, anionicpolyacrylamide/polyaminoamide-epichlorohydrin, cationic polyacrylamide and polyaminoamide-epichlorohydrin all can remarkabley improve the sizing efficiency basically due to their flocculating effect, and the combination of PAC with the selected organic polymeric compound cannot give observable effect.