| The research on waterborne epoxy resin emulsion, waterborne epoxy resin modified by polyurethane and waterborne anticorrosion coating system is not only of theoretical value, but also of great industrial value and environmental significance. At present, because of the difficulties in waterborne anticorrosion coating technology, the research is still on the initial stage. The key technologies, such as emulsion stability, water resistance of the coating, wet adhesion and mechanical strength, etc need to be solved. Aiming at the difficulties in waterborne anticorrosion coating technology, the research was focused on the relationship between resin structure and its performance; the stable composite emulsions were designed and prepared; the system of waterborne anticorrosion coating with waterborne primer, waterborne primer surface and waterborne top finish was designed and prepared, which mechanical properties and anticorrosion performance was improved.The main contents and conclusions are described as follows:(1) The polyurethane-epoxy composite emulsion with micro-gel structure was prepared by combination of crosslinking and blending modification technology. The synthesis process and the structure of the emulsion particles was characterized by Fourier transform infrared spectra (FTIR), transmission electron microscopy (TEM), gel permeation chromatography (GPC) and particle size distribution test. The emulsion was shown to be stable when the maximum content of epoxy resin was 20.0 % (based on the total solid of the polyurethane and epoxy resin), which was better than the literate reported. Its varnish film has excellent physical-mechanical properties and anticorrosion performance.(2) Two core-shell typed polyurethane-polyacrylate composite emulsions were prepared. One was crosslinking core-shell emulsion with an average diameter 330.0nm, and the other had a micro-gel core with an average diameter 27.2nm. Both emulsions were mono-dispersed. A dual-dispersed core-shell emulsion was prepared by blending the two mono-dispersed emulsions at a certain percentage. The results showed that the dual-dispersed core-shell emulsion has lowest viscosity, the lowest MFT (minimum film forming temperature, 3.2℃) and the best mechanical properties when mass ratio of large/small particles was 70/30.(3) Initial research was carried on the waterborne coating system. The two-component waterborne coatings, in which the polyurethane-epoxy composite emulsion was used as the binder, can be applied to anticorrosive coating for steel or iron materials as primer and primer surface. The single-package waterborne coating, in which the polyurethane-polyacrylate composite emulsion was used as the binder, can be used for top finish ariticorrosive coating system. The coatings can be cured at room temperature, and the coating properties can meet the needs of anticorrosive coating system.The main innovative points are as follows:(1) The emulsions with micro-gel structure were designed. The polyurethane-epoxy composite emulsion and the polyurethane-polyacrylate hybrid emulsion were synthesized with solution polymerization method and emulsion polymerization method respectively. Both emulsions had benefits to the preparation of coating resin emulsion with good stability (storage life: 6 months at room temperature), and the formation of film with high adhesion, good flexibility, and high mechanical strength (>50kgcm).(2) By molecular structure design and optimization of the chain extenders and the inner-crosslinker contents, the emulsion was stable when the maximum percentage of the epoxy resin was 20.0 %, which the result was better than the literate reports (percentage of the epoxy resin was lower than 12.0 %).The contradictions with particle size, viscosity and storage stability were successfully resolved.(3) Based on the morphology of the emulsion, dual-dispersed hybrid emulsion was prepared by blending two mono-dispersed core-shell polyurethane-polyacrylate emulsion (diameter ratio was 1:10) with a certain proportion, which can greatly improve the coating film properties of water resistance (>720h) and chemical reagents resistance(>360h).
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