一步间歇乳液聚合法制备高固含量大粒径窄分布聚丙烯酸丁酯胶乳

The Preparation of Poly( N-Butyl Actrylate) Latexes with High Solid,Large Scale and Narrow Distribution By One-step Batch Emulsion Polymerization

制备高固含量大粒径聚合物胶乳的方法主要是种子乳液聚合技术和附聚技术,然而这两种技术却很难简单地制备出粒子尺寸超过300 nm、窄分布、稳定的聚合物胶乳。介绍了一种可以一步制备出固含量高达60%、粒子尺寸大于600 nm、窄分布、稳定的聚丙烯酸丁酯胶乳的方法,并研究配方体系变量如乳化剂和电解质份数对聚合物粒子形成和增长方式的影响。实验研究表明,乳胶粒子的尺寸会随着体系乳化剂份数的增加而减小,随着电解质份数的增加而增大。通过研究反应过程中乳胶粒子大小和数目变化的关系,确定了乳胶粒子在成核与增长过程中存在着粒子聚并行为,这种聚并行为受粒子稳定性的控制。当聚合物粒子表面乳化剂覆盖率(θ)处于临界乳化剂覆盖率(θcri=0.59)和最低表面覆盖率(θlow=0.38)时,粒子聚并发生,促使粒子尺寸瞬间增大。

Seed emulsion polymerization and agglomerating technology were usually used to prepare high solid content latexes with large particle scale.However,it was difficult to obtain narrow distribution and stable polymeric latexes with particle scale beyond 300 nm.In this article,a new method to prepare narrow distribution latexes that solid content was beyond 60 wt％,particle scale greater than 600 nm was proposed; moreover,the effect of recipe composition included：surfactant concentration,solid content and electrolyte concentration,on latex particle formation and growth method was also investigated.Experimental results showed that the particle scale increased with the decrease in surfactant concentration,the increase in electrolyte concentration.The particle coagulation took place during the polymerization process,which could be demonstrated by the evolution of particle scale and number as a function of monomer conversion.In addition,the particle coagulation occurred if the ratio of the polymer particle surface covered （θ） by surfactant molecules between the critical particle surface covered ratio （θcri =0.59） and the lowermost surface covered ratio （θlow =0.38）.