硅烷偶联剂对聚硅氧烷及核—壳结构硅丙乳液聚合的影响

Influence of Silane Coupling Agent on Polymerization of Polysiloxane Emulsion and Silicone-acrylic Emulsion with Core-shell Structure

分别以偶联剂γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH-560)、γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH-570)以及两者的混合物与八甲基环四硅氧烷(D4)作为共聚合单体,采用乳液聚合的方法制备了聚硅氧烷乳液。然后以聚硅氧烷乳液作为种子乳液,以丙烯酸酯混合单体为原料制备了具有核-壳结构的硅丙乳液。研究了偶联剂种类及用量分别对聚硅氧烷和硅丙乳液聚合过程以及硅丙乳液浇铸膜吸水率的影响。采用TEM观察了硅丙乳液乳胶粒的形貌。结果表明,在聚合体系中加入硅烷偶联剂可以提高聚硅氧烷乳液的稳定性;以聚硅氧烷乳液为种子乳液可以制备具有核-壳结构的硅丙乳液,偶联剂的种类及用量对硅丙乳液聚合产生不同的影响,采用较低含量混合偶联剂的硅丙乳液的聚合稳定性、乳液稳定性及其浇铸膜的耐水性最好。

Polysiloxane emulsion was prepared by polymerization of octamethylcyclotetrasiloxane （D4 ） with γ- （ 2, 3 - epoxypropoxy ） propytrimethoxysilane, 3＇- （ methacryloxy ） propyltrimethoxysilane or the mixture of these two coupling agents. Then, silicone acrylic emulsion with core-shell structure was prepared by a seed emulsion polymerization method from methyl methacrylate （MMA）, butyl acrylate （BA） and methacrylic acid （MA） in the presence of polysiloxane emulsion. The effects of types and content of coupling agent on polysiloxane preparation, process of silicone acrylic emulsion polymerization and water absorption of the cast film of silicone acrylic emulsion were investigated. Moreover, the morphology of silicone acrylic emulsion was observed by TEM directly. The results indicated that the introduction of silane coupling agent improved the stability of polysiloxane emulsion. Silicone acrylic emulsion with core-shell structure could be prepared by using polysiloxane emulsion as emulsifier, while types and content of coupling agent have different effects on the silicone acrylic emulsion polymerization. When the dosage of mixed coupling agent was little in polysiloxane emulsion, the silicone acrylic emulsion exhibited excellently polymerization stability and emulsion stability. Furthermore, its cast films also have good water resistance.