Research On Acrylic Emulsion Particle Size Control Technology And Coating Performance

Acrylate emulsion is one of the major polymer emulsions, because of its superior film resistance, good water resistance and excellent cohesiveness, they have draw more and more attention. In the actual production process, the polymerization process fluctuations make emulsion polymerization reaction become very complex and control of polymerization process index more difficult, thus affecting the stability of the polymerization reaction and the influence on the structure and properties of the product. The study chose acrylic emulsion system, focusing on process factors and engineering factors affecting the reaction emulsion particle size, and reaction kinetics of the polymerization system, the purpose is to provide a reference for the classic emulsion amplification process and production practices.The styrene-acrylic emulsion was prepared by semi-continuous seeded-emulsion polymerization with MMA, BA and St as co-monomers. First, the influence of the preparation process and engineering process of the emulsion were investigated. The experimental results show that pre-emulsion added dropwise get the smallest size; the particle size of emulsion is96nm and the distribution width is the narrowest when the concentration of emulsifier is10%; the same concentration of the emulsifier in pre-emulsification process, the particle size of emulsion is104nm when the concentrate of the seed emulsion is40%; the particle size does not change when the dropping rate of pre-emulsion is less than163mg/s, the dropping rate of initiator is less than11.5mg/s. TEM analysis shows the nucleation growth mechanism that the latex particles growth in the emulsion polymerization process, and particle morphology control has been achieved. The position of the impeller is30mm and the n stirring speed is250rpm; with the impeller diameter increases, the emulsion particle size decreases and the particle size distribution width narrows.By analysis of the reaction temperature, initiator concentration, emulsifier concentration, St and MMA concentration and polymerization rate to determine the kinetic characteristics of the experimental system. The results show that:Ea=19.32kJ·mor1; Rp∞[I]0.44, Rp∞[E]0.15, the reaction follows the homogeneous nucleation mechanism. St monomer significantly affect the polymerization reaction, Rp^[St]0.18.We also study on different properties of different particle size of the emulsion The results show that:the size of the emulsion particle size affects the quality of the film, fine particle size emulsion paint to be more uniform and high gloss, transparency, and hardness increases. the SEM shows good film-forming properties of different particle size emulsion, homogeneous and transparent. Cold resistance (except for14days outside) and boiled water resistance were poor, shows white phenomenon. alcohol resistance were excellent after curing 3days. The emulsion shows pseudoplastic characteristics, and the viscosity decreases with particle size increased.