Auxiliary Materials Of Cationic Rosin Size

Rosin extenders and mordants were the research highlights of this paper in order to improve the sizing efficiency of cationic rosin size. Unmodified C5 petroleum resin, C9 petroleum resin and their mixtures were used as the extenders and melted together with natural rosin repectively to prepare cationic rosin size emulsions and used as internal sizing agents. The effects of C5 and C9 petroleum resin proportion, the addition levels of alum and cationic rosin sizes, pH value as well as pulps on the sizing degree of hand sheets were investigated. The results show that the cationic rosin sizes with C5 petroleum resin, C9 petroleum resin as well as their mixture as rosin extenders are more effective in internal sizing than the cationic rosin size without extender. When the mass ratios of the C5 petroleum resin, C9 petroleum resin and their mixture to rosin are 1:5, 1:10 and 1:10 repectively while the C5/C9 is 2:1 in the mixture, the obtaind cationic rosin sizes show high sizing efficiency. The cationic rosin sizes with C5 and C9 petroleum resin provide higher sizing degree than usual cationic rosin size even under the neutral condition of pH 7, although the sizing degrees decrease as pH value rises.The function of the petroleum resins on the stability and sizing performance of the cationic rosin sizes was analyzed by means of the sizing degree measurement of hand sheets, infra-red technology, XRD and XPS. It is found that the addition of C5 and C9 petroleum resins as rosin extenders can significantly lower the content of carboxyl groups in rosin sizes and the ratio of O/C on the surfaces of rosin sizes since both C5 and C9 petroleum resin are hydrocarbon resins. The addition of petroleum resins also reduce the short-range-order domains of cationic rosin sizes, which means that petroleum resins can lower the trend of rosin crystallization. Meanwhile, XPS analysis also confirms that the carboxyl groups tend to distribute on the surfaces of rosin size particles while the petroleum resins tend to locate in the outer surfaces of the rosin sizes. Therefore, the petroleum resins have significantly increased the hydrophobicity of rosin size film, improving the sizing efficiency of cationic rosin sizes.In view of the develpment towards alkaline sizing, ammonium zirconium carbonate (AZC) was selected as the new mordant of impregnated rosin sizing. The synergistic sizing effects of cationic rosin sizes with AZC, alum and both of them were investigated. The results show that AZC performs very well as the mordant of rosin sizing under neutral conditions. When the mass ratio of rosin to AZC is 4:1, high paper sizing degree was obtained. However, when aluminum sulfate and AZC are used together, they will interfere with each other and the sizing degree of rosin sized paper is lower than the case that they are used separately.Finally, to further improve the sizing efficiency of the cationic rosin sizes, PAE was employed as accelerant to investigate its function in the rosin sizing. It is discovered that PAE can significantly improve the sizing efficiency of the cationic rosin size/aluminum sulfate system. When it is added before the aluminum sulfate and cationic rosin sizes, it will show the highest promoting effect for sizing. Its suitable addition level is 0.1% based on oven dried pulp.