Study On Synthesis Of Polyurethane-epoxy Resin Composite Emulsion For Anti-corrosive Coatings

A kind of polyurethane-epoxy resin composite emulsion was prepared through grafted polymerization of epoxy resin whose epoxy group was opened by ethyl enediamine (EDA) to form crosslinking structure and partly terminated hydrophilic polyurethane prepolymer, which was synthesized by using toluene diisocyanate (TDI), polyether diol (Diol-1000), dimethylolpropionic acid (DMPA) and absolute alcohol as main raw materials.Technological and formulation factors of the synthesis of polyurethane-epoxy resin composite emulsion have been inspected. The impacts of factors such as material dehydration, addition mode, the content of DMPA, the content of epoxy resin, grafting ratio of epoxy resin, the neutralization degree and ethylenediamine content etc on emulsion and coating properties were inspected. When the DMPA and solid epoxy resin were dissolved or molten in the form of liquid to add; content of DMPA was 8%～8.5%; content epoxy resin was 45%; grafting ratio of epoxy resin was 95%～99%; neutralization degree was 95%～100%; open-loop ratio was 100%; the composite emulsion and film have the best properties.The particle size of the emulsion was detected by laser particle size analyzer; the spectrogram of polarization curve was detected by electrochemical workstation, then we get the anti-corrosion of film; heat resistance was detected by integrated thermal analysis; the surface morphology of the film was detected by TEM; resistant to salt spray of film was detected by salt spray test box. Difficult content of epoxy resin, difficult grafting ratio of epoxy resin and difficult open-loop ratio of epoxy group of film were compared on anti-corrosion, we found that the higher of the epoxy resin content, the grafting ratio and the open-loop, the film has the better anti-corrosion.The appearance of the polyurethane-epoxy resin composite emulsion is white, translucent, bluish and stable. It can be applied in the preparation of waterborne anti-corrosion coatings, whose excellent properties are following:pencil hardness 2H,48h water absorption≤25%, flexibility≤1mm, the adhesion level 1, excellent water resistance and anti-corrosion.