pH值和金属阳离子对水性油墨胶体稳定性的影响

Effect of Inorganic Electrolytes on the Colloidal Stability of Water-Based Inks

研究了pH值和Na+、Ca2+、Al3+对水性油墨胶体体系稳定性的影响。研究结果表明,当pH值<4.0时,水性油墨胶体体系发生失稳现象。pH值为3.1时,水性油墨粒子Zeta电位达到等电点,pH值<3.1时油墨粒子表面带正电荷。加入Na+、Ca2+和Al3+均可增加水性油墨粒子的平均粒径,而Al3+的效果最为显著,当Al3+浓度为0.005mol/L时,炭黑聚集体的粒径可达到5210nm,体系的Zeta电位为5.2mV。降低pH值及添加Al3+均能明显降低水性油墨的浊度值并使油墨粒子发生明显的聚沉作用。

The effects of pH and inorganic electrolytes such as Na^＋ , Ca^2＋ , Al^3＋ on the particle size and zeta potential of water-based inks were studied in this paper. Results showed that water-based inks became unstable when pH 〈 4.0. Water-based inks reached the point of zero charge （PZC） at a pH of 3.1, where ink particles were positively charged. The size of ink particles increased by adding Na^＋ ,Ca^2＋ ,Al^3＋ , of which Al^3＋ had the most remarkable effect. When the Al^3＋ concentration was 0.005mol/L, the average particle size and zeta potential of the ink were 5210 nm and 5.2mV, respectively. The colloidal stability of water-based inks was mainly attributed to both an electrostatic repulsion and a steric stabilization. Results also showed that turbidity of the water-based inks apparently decreased and the ink particles obviously coagulated by decreasing pH value and adding Al^3＋.