Synthesis And Modification Of Waterborne UV-cured Polyurethane Acrylates

In this thesis, the waterborne UV-cured polyurethane has been synthesized by sub-step method. Firstly, prepolvmer I was synthesized using toluene diisocyanate (TDI) and polyethylene glycol (PEG). Secondly prepolymer â…¡ was synthesized by the prepolymer â…  and double-(hydroxymethyl) propionic acid (DMPA). Finally prepolymers â…¢ was synthesized by prepolymer â…¡ and hydroxyethyl methacrylate (HEMA), after beening neutralized and emulsified the waterborne UV-cured urethane acrylate (UV-WPUA) emulsion was attained, and then epoxy resin (E-44) and silicone (KH-550) were used to modify the UV-WPUA.The effect of the mole ratio of-COOH/-OH on the properties of the film and emulsion has been researched. The film performance and properties of the emulsion of the modified UV-WPUA were studied. The effect of choice of neutralizer type and neutralization degree, as well as the amount of initiator, drying temperature, drying time on photo-curing speed of the emulsion has been discussed.The results showed that, for waterborne UV-cured polyurethane resin, with the mole ratio of-COOH/-OH increases, the pencil hardness, impact strength, tensile strength and other properties improve of the coating film, but the water absorption increase. While for the emulsion, with the mole ratio of-COOH/-OH increases, emulsion particle size was decreased, the stability of the emulsion was enhancement and the appearance turn from milky and opaque to yellowish and transparent. With the content of hydrophilic groups and neutralization degree improvement, the molecular chain hydrophilicity was enhanced, the dispersion and stability of the emulsion were improved. When triethylamine and triethanolamine was used as the neutralizing agent, a good water-soluble WPU can be attained. While ammonia was used as the neutralizing agent, the water-solubility was poor. When triethanolamine was used as a neutralizer. the curing membrane easily moistened, therefore triethylamine was finial decided as a neutralizer. With the amount of photoinitiator increases, the photo-curing speed improved. When addition of photoinitiator was less or more than3%, the resin need cure more than three times.3%is the optimal addition in this paper.The waterborne UV-cured polyurethane resin was modified by organic silicon and epoxy. respectively. The results showed that, for the WPU modified by organosilicon, the water absorption of the film was declined, and adhesion was improvement, while the pencil hardness was slightly decreased, the appearance of the emulsion turn yellowish to deep yellow, and emulsion storage stability also decreased; for the WPU modified by epoxy resin, water absorption of the film was greatly declined, the adhesion force, pencil hardness were enhanced, and the appearance of the emulsion turn from yellowish to deep yellow, and storage stability become poor. After the WPU was modified by organosilicon or epoxy resin, the films showed good heat resistance and solvent resistance.