Studies On Synthesis And Properties Of The Novel UV-Curable Water-Borne Polyurethane Acrylate

Ultraviolet (UV)-Curable waterborne polyurethane acrylate resins have gained more and more atention and speedy development in the past years as result of the merits in environmental protection, lower energy consumption and excellent propertie. The most of them are based on the single hydroxyl-terminated acrylate, therefore, only very limited content of double bonds can be incorporated into the polyurethane backbones, as well as, the water resistance and thermal resistance of the polyurethane based on polyester polyol and polyether polyol are very poor. The hydrodiol containing unsaturated group can be incorporated into the polyurethane backbones reacted with diisocyanate to crosslink, and the polycarbonate diols instead of polyester polyol and polyether polyol was incorporated into the polyurethane backbones, the properties of the coating can be improved because of the water resistance and thermal resistance. The related reports of this are spare.The novel UV-curable water-borne polyurethane acrylate prepolymer containing more double bonds and carboxyl group were prepared from 1,1,1-trimethylolpropane (TMP)-based diol which was synthesized by TMP and maleic anhydride (MA), toluene-2, 4-diisocyanate (TDI) and 2-hydroxyethyl acrylate (2-HEA). The control processes of the synthesis was determined by N, N-dibutylamine reverse-titrate method and FT-IR.In-situ Fourier transform Infrared spectroscopy was employed to investigate the kinetics of noncatalyzed of the polycondensation process between toluene-2, 4-diisocyanate (TDI) and polyethers diol. These studies showed that when the reaction was divided into two phases, a reasonable fit of the reaction profile could be approved with the second order rate equation for every phase firstly. The kinetics constants at different phases were obtained and then the activation energies were also obtained.A series of the UV-curable waterborne polyurethane acrylate resins were obtained based on the different kinds of polycarbonate diols and diisocyanate (NCO). These studies on properties of resins showed that: the system of uv-curable waterborne resins was stable emulsion when the content of carboxyl group was 0.2-0.6 mmol/g, the size of particles in emulsion was minished obviously when the content of carboxyl group was increased, as well as the viscosity was increased. The appearance of the system was changed from unstable emulsion with little yellow to unstable ivory-white emulsion with little blue ligh with the increase of neutralization. Studies on properties of UV-curable showed that: neutralized with triethylamine, degree of neutralization was 80%, Darocur 1173 as the photoinitiator with the dosage 2% in prepolymer.