硅溶胶/聚丙烯酸酯复合乳液的制备及其性能研究

Study on Preparation and Performance of Silica Sol/Polyacrylate Composite Emulsion

以正硅酸乙酯(TEOS)水解缩合后形成的硅溶胶代替商用硅溶胶,采用乳液聚合法合成了硅溶胶/聚丙烯酸酯复合乳液.研究了TEOS水解pH值、乳液聚合温度、TEOS用量(质量分数)等因素对复合乳液性能的影响,并用傅里叶红外光谱(FTIR)仪和透射电子显微镜(TEM)对复合乳液微观结构进行分析.结果表明:最佳TEOS水解pH值为5.7～6.5,最佳乳液聚合温度为75℃;随着TEOS用量的增大,复合乳液的稳定性增强,乳液涂膜硬度也增大,但当TEOS用量过大时,复合乳液发生沉降,涂膜也发生开裂,故TEOS的最佳用量为9%～13%;TEOS在水中发生了水解缩合反应,复合乳液是SiO2和聚丙烯酸酯的复合物;TEOS水解缩合产生的SiO2可起到稳定剂的作用,因此乳液聚合过程中不添加其他稳定剂.

Silica sol/polyacrylate composite emulsion was prepared via emulsion polymerization with the product of hydrolyzed and condensed tetraethoxysilane（TEOS） instead of the commercial silica sol. The in- fluences of pH value for TEOS hydrolysis, emulsion polymerization temperature and TEOS content （by mass） on the properties of composite emulsion were studied, and the Fourier transform infrared spectroscopy（FTIR） and transmission electron microscopy（TEM） were used to characterize the composite emulsion. The results show that the optimum pH value range for TEOS hydrolysis is 5.7-6.5, and the optimum emulsion polymerizaiton temperature is 75 ℃. With the increment of TEOS content, the stability of composite emulsion and the hardness of the film increase. However, composite emulsion will deposit and the film will crack with excessive TEOS. Experiments show that the optimum content of TEOS is 9%- 13%. In the preparation process, TEOS hydrolyzes and condensed to form complex of silica sol and poly- acrylate. TEOS is used as silica sol and stabilizer, and the polymerization is carried out without additional stab lizer.