Studies On Synthesis Technology And Behavior Of Waterborne Polyurethane Applied In Coatings

Waterborne polyurethane which is by using water as medium, with the advantages of fireproofing, nonharmfulness and nonpollution and its film with the performances of high strength, good flexibility, excellent adhesive force, becomes one of the important development direction of polyurethane industry. Based on much paper about synthesis methods and synthetic technology and application and development situation of waterborne polyurethane are reviewed. Shortness of hardness and water abortion of waterborne polyurethane, modified waterborne polyurethanes in performances of hardness and water abortion are synthesized by use of the materials—TDI and IPDI, and different structural chain extenders.Materials ratio and synthetic technology of waterborne polyurethanes are studied by use of the materials—IPDI in which a suitable preparation technology picked up.Series of products are prepared by using TDI and IPDI. In addition, the effect of EDA, ethanolamine, diethylenetriamine and tetraethylene pentamine to PU behavior — water abortion, weather resistance, hardness, flexibility, viscosity, adhesive force, tensile strength, elongation, stress, impact strength is studied hi detail.IR and TEM shown, the contains the linear structure by using EDA as chain extender in the sample and contains the cross-linked structure by using diethylenetriamine and tetraethylene pentamine as chain extender in the sample. Thus the performances of the latter in the water abortion and hardness are more excellent than the former.When prepared with IPDI and by using EDA, diethylenetriamine and tetraethylene pentamine as chain extender, DSC of the samples shown: the micro-phase separation between the soft-segment and the hard-segment of the WPU exists; it is the most excellent in the sample of by using ethanolamine,diethylenetriamine as chain extender on the extent of the micro-phase separation; Tg of the hard-segment enhances with increasing hard-segment content and forming much H-bonds.According to analysis of experimental data, the water abortion and hardness of WPU can be modified by using compounds which contain multi-faction group as chain extender.