Study On The Synthesis And Modification Of High Stable Polyester Anionic Waterborne Polyurethane Emulsion

In recent years, a major change in coatings technology is caused by the restrictions on volatile organic compounds(VOC) in coatings. These government regulations combined with performance advantages are the key to the success of waterborne polyurethane. It is caused a wide range of attaching importance because waterborne polyurethane has outstanding comprehensive property and good environmental protection effect. Up till the present moment, the great majority waterborne polyurethane is belong to polyester in our country, it could not matched by the external same products in mechanical property and other. In this paper, the stable polyester anionic waterborne polyurethane emulsion was prepared by acetone process with toluene diiosocynate(TDI), polyester polyol (JW2503), diglycol(DG) and dimethylolpropionic acid(DMPA) as the main material. The products has good storage stability, and its received high appraisals of the national interrelated factory and customer. This paper is mainly discussed on several aspects listed below:Firstly, A kind of theoretical model to the reaction kinetic of the urethane and branching reaction of polyurethane prepolymer is proposed, and the prepolymerization of TDI and JW2503 was studied.Secondly, the reaction condition was determined and The effects of the mole ratio of NCO/OH, reaction temperature, reaction time, the amount ofcatalyst, the category of hydrophilic extender, the category of neutralizer and neutralization degree of hydrophilic extender on the properties of the emulsion and the water resistance, solvent resistance, thermal and mechanical properties of the film casted from the emulsion were discussed in detail. FTIR spectrum and DSC of the cast film showed that hydrogen bonds existed between the hard segments and the soft segments, and microphase separation was formed, which played a very important role on the mechanical properties.Finally, waterborne polyurethane emulsion is modified with polyacrylate (PA) by the ways of mechanical blending, and the modifying effects are studied. The results show that the particle size of mechanical blending emulsion are changed and water resistance, solvent resistance, thermal and mechanical properties of the emulsion cast film are apparently improved, compared with polyacrylate and unmodified waterborne polyurethane emulsion.