pH值和金属阳离子对水性油墨胶体稳定性的影响

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。

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

The effects of pH and inorganic electrolytes such as Na ,Ca2 ,Al3 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 ,Ca2 ,Al3 ,of which Al3 had the most remarkable effect.When the Al3 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 Al3 .