| In recent years, with the increase of environmental pollution, especially the chemical pollution poses a great threat to the ecological protection and human health, so a wave of protect environment is raised in the global. In contemporary society, with the increase of people's living standard, people attaches great importance to appearance and quality of family decoration. So people take more and more attention for environmentally friendly products such as waterborne architectural coatings. Moreover, the latex paint is of great important waterborne architectural coatings with more wide scope of application and there is more and more strict for quality and now a lot of emulsion used the latex paint have been developed.This thesis study the hottest and best cost-effective coating emulsion, namely styrene acrylic emulsion, which has many advantages including excellent water resistance, alkali resistance, washing resistance and resistance to outdoor, strong adhesion, low price and simple preparation process. But the content of volatile organic compounds (VOC) of polymerization is still high, which makes its application limited. Through adding a kind of natural olefins such as sunflower seed oil and rosin, which have double bond and widely source, which can participate in the copolymerization with other monomers in order to improve the monomer conversion rate, and reduce the content of VOC, preparing environmentally friendly styrene acrylic emulsion which has low VOC content and steady performance. Three aspects of the paper were studies in the following:The first part, we put the St/BA/AA copolymer as a research system. Acrylic emulsion was prepared by the composite method of pre-emulsion and seed emulsion polymerization technology. The effects of stirring speed, temperature, compound emulsifier's amount, amounts of initiators, the amount of acrylic acid on he performance of the styrene-acrylic emulsion and monomer conversion, formation of coagulum, viscosity, particle size, water absorption of latex film were studied. And the related performance of styrene acrylic emulsion was determined and the structure of styrene-acrylic emulsion was characterized by Fourier transform infrared spectroscopy. The better synthetic condition of styrene acrylic emulsion is educed:reaction temperature is 78?; the contents of emulsifier is 3%; the ratio of surfactants is 2:1; initiator content is 0.2%; the content of acrylic acid as functional monomer is 2.4%.The second part, sunflower oil participates in the copolymerization with other monomers in order to reduce the content of VOC. Based on the basis of experiment of the first part, we have a systematic study on the effects of content of sunflower oil, temperature, compound emulsifier's amount, amounts of initiators on the performance of the styrene-acrylic emulsion and monomer conversion, formation of coagulum, viscosity, particle size, water absorption of latex film. The better synthetic condition of styrene acrylic emulsion is obtained, which is the optimal content of sunflower oil of 1%; reaction temperature of 78?; the contents of emulsifier of 2.5%; the ratio of surfactants of 2:1; initiator content of 0.3%; In the polymerization reaction, through adjusting the content of sunflower oil, the conversion rate of the monomer is optimized and the goal VOC is controlled within environmental scope.The third part, based on research and exploration of preparing styrene acrylic emulsion of natural olefins, pilot tests are performed. Parameters of product is monitored. Performance of the final products is tested. The best formulation of this relatively new research product is further confirmed and we hope that it will be applied to industrial production as soon as possible. |
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