Synthesis And Characterization Of Modified Styrene-Acrylic Emulsion And Study Of Coating

In this thesis, the study of styrene-acrylic emulsion modified by organosilicon both at home and abroad was reviewed. The stable styrene-acrylic emulsion modified by organosilicon was prepared by preemulsified addition. The performance and characterization of the product was studied. The effect of surfactants, initiator, content of organosilicon, temperature on modified styrene-acrylic emulsion was investigated,and the best formulation of emulsion modified by organosilicon was determined. The best formulation condition of modified emulsion could be obtained when the contents of surfactants was 3%, the ratio of surfactants was 1/3, the contents of reactive surfactant was 1%, the content of initiator was 0.6%, the best polymerization temperature was 75℃～80℃, the ratio of soft monomer to hard monomer was 1/1, the content of organosilicon was 2%. The structure of styrene-acrylic emulsion modified by organosilicon was characterized by Fourier transform infrared spectroscopy, the peaks at 842cm-1 and 1030cm-1 correspond respectively to the stretching motion of Si-C and Si-O, so organosilicon have joined in the polymer. The differential scanning calorimetry was employed to monitor the glass transition temperature of styrene-acrylic emulsion modified by organosilicon(Tg=20℃),this temperature was bigger than unmodified styrene-acrylic emulsion(Tg=15℃). The thermal graviting analysis was employed to monitor the thermal stability of emulsions, found that the thermal stability of modified emulsion was higher than unmodified emulsion. The stability of frost and thaw and proofwater tests confirmed that the styrene-acrylic emulsion modified by organosilicon possessed higher thermal stability, waterproof ability compared to styrene-acrylic emulsion.The coating was prepared with modified styrene-acrylic emulsion. When some performances of coating was studied, we found that the waterproof ability and weatherproof ability of modified coatings exceeded unmodified coatings. The effect of various additive agent on the coating was investigated, the results showed: the best content of defoamer was 0.6%～0.8%, the content of film additive was 1.5%～2.0%, the content of leveling agent was 0.1%～0.15%, the content of bodying agent was 0.2%～0.3%, the content of dispersant was 1.0%～1.2%, the best formulation of coating modified by organosilicon was obtained.