Study On The Synthesis And Properties Of Water-borne Polyurethane Hyperdispersant

Polymeric dispersant is also called "hyperdispersant", the surface wettability of hyperdispersant is better than the traditional surfactants. It has been widely applied in the area of coating, paint, ink, filling plastic, ceramic, biological materials, medicine and food, etc. The traditional solvent dispersants contain a lot of organic solvents which may cause environmental contamination. And the prices of organic solvents are rising nowadays. So the exploitation of water-borne polyurethane hyperdispersant has important research meanings and broad application prospect in consideration of the energy conservation, environmental protection and cost reduction.In this thesis, based on the way of molecular design, with gradually polymerization technique, two kinds of water-borne polyurethane hyperdispersants were synthesized by the reactions that use polyethylene glycol,1,6-hexandiol and toluene diisocyanate as raw materials, butanone as solvent,2,2-dimethylol propionic acid as hydrophilic chain extender, dibutyltion dilaurate as catalyst, β-hydroxyethyl methacrylate and polyethylene glycol single methyl ether as blocking agent. The structures of the hyperdispersants were characterized by FT-IR,1H-NMR spectrum and GPC. Based on the structure characteristics, they were named as water-borne photosensitive polyurethane hyperdispersant and nonionic water-borne polyurethane hyperdispersant, and called WUVPU and NWPU for short.As the synthesis of polyurethane prepolymer was the control step of the synthesis process. In this thesis, the synthesis conditions of WUVPU prepolymer were determined by the di-n-butylamine method. As a result, the reaction time and reaction temperature were3h and80℃respectively, the catalyst dosage was0.2%of the total weight. And the dispersion effect of the hyperdispersants emulsion was investigated by the absorption spectrophotometry. The appropriate synthesis conditions of WUVPU were optimized by single-factor experiments. The conditions were as follows:the amount of DMPA addition was7%of the total weight, the neutralizer was triethylamine, the extent of the neutralization was100%, the mole ratio of NCO/OH was1.0. With the same method, the appropriate synthesis conditions of NWPU were as follows:the synthesis time of prepolymer was3h, reaction temperature was60℃, the mole ratio was n (1,6-hexandiol):n (TDI):n (polyethylene glycol single methyl ether)=4:5:2.The coatings properties of WUVPU were investigated, the influences of curing time and photoinitiators dosage were researched, and the temperature resistance of the coatings was determined by TG. The results were as follows:the curing time was10s, the best photoinitiators dosage was1%of the total weight. Under these conditions, the adhesion, hardness and temperature resistance of the coatings were excellent. The effects of different dosage of WUVPU and NWPU on the viscosity, particle size and dispersion stability of the dispersion system were studied. The results showed that the best dispersant dosage were1%and3%of the total weight. Under these conditions, both of the hyperdispersants had good dispersibility and abilities to endure the change of the temperature.