| Polyurethane-acrylate (PUA) hybrid emulsion has both the excellent properties of the polyurethane (PU) emulsion and the polyacrylate (PA) emulsion, which has been extensively researched and applied in waterborne wood furniture paintings. However the film shortages such as low adhesion, low density and high contractility, limit its application in the field of metal anti-corrosion coatings.In this paper, we synthesized the epoxy resin based polyol by the ring-opening reaction between diethylamine and the epoxy group of an epoxy resin, then the content of the epoxy resin in the polyurethane-acrylate hybrid emulsion had been greatly improved, the obtained epoxy-modified polyurethane-acrylate (PUEA) hybrid emulsion film had excellent corrosion resistance.With main raw materials such as epoxy resin (CYD-014) and diethylamine, the epoxy resin based polyol was obtained by the ring-opening reaction of the epoxy group in the epoxy resin, and the epoxy resin based polyol was used as a modifier.With main raw materials such as toluene diisocyanate (TDI), polyether diols(GE-220), dimethylol propionic acid(DMPA), epoxy resin based polyol, methyl methacrylate (MMA), an inner-emulsion type of polyurethane prepolymer with-NCO ending had been successfully synthesized by the "prepolymer method", then the methyl methacrylate monomers were wrapped in the process of chain extending reaction in the water. Finally the epoxy-modified polyurethane-acrylic hybrid emulsion was synthesized by emulsion polymerization method.The best conditions of the epoxy ring-opening reaction were:the molar ratio of the ring-opening agent and the epoxy group was1.2:1, the ring-opening reaction temperature was70℃, and the ring-opening reaction lasted5h.In the synthesis stage of prepolymer, when the initial-NCO/-OH was14in molar ratio, the total-NCO/-OH was1.45in molar ratio, the DMPA content was7%-7.5%, the epoxy resin based polyol content was12%, the amine chain extender ratio was20%-30%, the neutralization degree was95%-100%, we found that the hybrid emulsion and the film properties were desirable.In this paper, we used AIBN as the initiator. When the AIBN concentration was1.4%, the amount of MMA was25%, the hybrid emulsion and the film properties were desirable. The epoxy resin modified polyurethane-acrylate hybrid emulsion and the film properties were tested, characterized and analyzed. Fourier transform infrared (FTIR) was used for confirming the structure of the polyurethane-acrylic hybrid emulsion modified by epoxy resin. The epoxy resin based polyol participated in the polymerization. Transmission electron microscopy (TEM) showed that the dispersion of the particle was quite uniform and an obvious core-shell structure had been observed. The thermogravimetry (TG) curves indicated that the final film had good heat resistance. The epoxy-modified polyurethane-acrylate hybrid emulsion obtained in this study had good film performance, high gloss and excellent corrosion resistance. |
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