Synthesis And Research Of Core-shell Styrene-Acrylic Emulsion Through Reactive Emulsifier

The styrene-acrylic emulsion is widely used in the waterborne glazing oil because of its low cost, good adhesion, strong contamination resistance, excellent weatherability. In order to overcome the effects of emulsifier on film in traditional styrene-acrylic emulsion, reactive emulsifier was synthesized firstly. Then the styrene-acrylic emulsion with core-shell structure (polystyrene as core and polyacrylic-styrene as shell) was prepared by core-shell emulsion polymerization technology. The styrene-acrylic emulsions with core-shell structure, which is high gloss, good film-forming property, abrasion resistance, water resistance. It can be used for waterborne glazing oil.Anionic reactive emulsifier with carboxylic group was synthesized by toluene diisocyanate (TDI), dihydroxy methyl propionic acid (DMPA) andβ-hydroxyethyl methacrylate (HEMA). The Hydrophilic Lipophilic Balance is48.84, Critical Micelle Concentration (CMC) is1.95×10-1mol/L, and the relative molecular weight is1010.The polyacrylate-styrene (PAS) chain containing carboxyl was prepared though free radical copolymerization and solution polymerization by the reactive emulsifiers, styrene (St), butyl acrylate (BA) and acrylic acid (AA). It was dispersed in water together with core monomer St subsequently. Finally, a core-shell styrene acrylic emulsion was gained through the emulsion polymerization of core monomers.When the amount of initiator AIBN is between1and1.2percent of shell monomers, the dosage of AA is12-16%, the content of emulsifier is3%, the reaction process of PAS dispersion preparation is steady with excellent self-emulsifying results. At the speed of6000rpm, using the gas dispersion method for dispersing, appearance of PAS dispersion and emulsion were good. In the emulsion polymerization of core monomers, when the dose of AIBN is2.0percent of core monomers, the amount of core monomers is25%. The monomer conversion rate can reach95%under83-85℃for3hours. Furthermore, the size of emulsion particle is small and distributed evenly. The minimum film-forming temperature of the emulsion is about15℃. And the performance of emulsion and coating film were better.The molecular structure of reactive emulsifying agent and emulsion polymer were characterized by Fourier infrared spectrum (FTIR), and the results are consistent with experimental design. The latex particle of styrene-acrylic emulsion has a clear core-shell structure through transmission electron microscope (TEM). The laser particle size analyzer test shows that the emulsion’s average particle size is about106nm with a narrow size distribution.