复合分散剂对高岭土的分散作用机理研究

Study on the Dispersing Mechanism of Kaolin by Compound Dispersants

分散性是造纸用高岭土的重要参数之一,为分析复合分散剂对高岭土分散性能的影响机理,选用六偏磷酸钠(SHMP)和聚丙烯酸钠(DC)分散剂作为单一分散剂,并按质量比1∶1将其复合制备复合分散剂,研究分散剂对高岭土黏度的影响。结果表明,复合分散剂用量在0.2%时,高岭土黏度最低,为363 mPa·s,其用量相比单一分散剂DC和SHMP分别减少33%和60%,最低黏度分别降低503 mPa·s和260 mPa·s;高岭土表面Zeta电位由-31.4 mV降至-46.6 mV,沉降总高度由57 mm降至5.5 mm,分子间排斥作用能相比单一分散剂显著提高。这是因为复合分散剂中,六偏磷酸钠与DC吸附在高岭土上,发生协同作用,在降低分散剂用量的同时,降黏效果也更好。

Dispersion is one of the most important parameters of kaolin used in paper making.In order to further analyze the dispersing mechanism of composite dispersants on kaolin,sodium hexametaphosphate(SHMP)and sodium polyacrylate dispersant(DC)were used as single dispersant,and under the mass ratio of them being 1∶1,the composite dispersant was prepared,the influence of dispersant on the viscosity of kaolin was studied.The results showed that when the dosage of composite dispersant was 0.2%,the viscosity of kaolin was the lowest(363 mPa·s),which was 33%and 60%lower than that of single dispersant DC and SHMP,and the minimum viscosity was also reduced by 503 mPa·s and 260 mPa·s,respectively.The Zeta potential of kaolin surface decreased from−31.4 mV to−46.6 mV,the total deposition height decreased from 57 mm to 5.5 mm,and the intermolecular repulsion could be significantly increased when 0.2%compound dispersant was added.Synergistic effects were observed for the composite dispersant containing both sodium hexametaphosphate and DC,which not only reduced the amount of dispersant,but also reduced the viscosity of kaolin pulp.