The Study Of Synthesis And Modified Of Cationic Waterborne Polyurethane Synthetized By MDI

The waterborne polyurethane is a water continuous phase, polyurethane particles as the dispersed phase of the eco-friendly polymer materials. It has the advantages of non-poisonous, low VOC content, great value for application and prospects for development. Waterborne polyurethane based on the dispersed particle electric charge can be divided into cationic waterborne polyurethane, anonic waterborne polyurethane and non-ionic waterborne polyurethane. In recent years, the reports on the anonic waterborne polyurethane modified research and application is relatively large, but the cationic waterborne polyurethane and non-ionic waterborne polyurethane is relatively small studies. Bacause the cationic waterborne polyurethane has its own unique characteristic with great potential application, so research and application of the cationic waterborne polyurethane need to be developed, especially the research and application development on a new type of cationic waterborne polyurethane prepared by other new isocyanate.At present, the research reports on cationic waterborne polyurethane is various types, most of them use isophorone diisocyanate and toluene diisocyanate as the isocyanate raw materials, research and development on the cationic waterborne polyurethane prepared by other types of isocyanate is relatively weak. Due to the regularity of molecules and special atructure of two benzene rings of Diphenyl methane diisocyanate (MDI), the polyurethane material with excellent performance can be prepared by it. Many solvent-based polyurethane are used as the isocyanate. In this work, MDI was selected as isocyanate raw materials to try the synthesis of cationic waterborne polyurethane.In this work, cationic waterborne polyurethane dispersions (PU) with different of content of the N-methyl diethanolamine (MDEA) and MDI is synthesised by MDI, polypropylene glycol (PPG, N-210), diethylene glycol(DEG), the N-methyl diethanolamine (MDEA), followed by characterized the synthesis of PU, particle size of PU, structure of polyurethane, tensile, hardness, thermal, water resistance, acid resistance, alkali resistance and contact angle of polyurethane films by Fourier transform infrared(FTIR), particle size analysis, mechanical analysis, hardness analysis, thermal gravimetric analysis(TGA), differential scanning calorimetric (DSC), water resistence analysis, acid resistance analysis, alkali resistance analysis and contact angle test of polyurethane films. Research and testing results show that content of MDEA has a important influence on synthesis of PU. Synthesis of PU is difficult when content of MDEA is too large. And hydrogen bond between soft segment and hard segment, tensile strength, water resistance, acid resistance and alkile resistance are destroyed when content of MDEA is enhanced. When cotent of MDI is enhanced, change of characteristic of the polyurethane films is opposite campared with influence of changing content of MDEA. Content of MDI is enhanced, which is benefited for hydrogen bond between soft segment and hard segment, tensile strength, water resistance, acid resistance and alkile resistance of the polyurethane films.The cationic waterborne polyurethane dispersions (CPU) modified by caster oil is synthesised by caster oil(CO), MDI, PPG, DEG, MDEA. Caster oil is added in prepolymer at the first step. Structure of polyurethane, state of dispersions and characteristic of polyurethane films is characterized by Fourier transform infrared (FTIR), particle size analysis, mechanical analysis, hardness analysis, thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC), water resistence analysis, acid resistance analysis, alkali resistance analysis and contact angle test of polyurethane films. Research and testing results show that particle size of dispersions is larger, and thermal and hardness of films is no change. But tensile strength of films is improved about24.7%when content of CO is9.33%. In additon, water resistance, acid and alkile resistance is also significantly improved. The ability of the surface hydrophobicity of the material is also improved.