Preparation And Research Of Epoxy Resin Modified Waterborne Polyurethane

The diphenyl methane diisocyanate (MDI) and polyethylene glycol (PEG) wereselected to prepare series of polyurethane resin by using chain exender, catalyst, andneutralizer. The influence of such factors as the reaction time, reaction temperature, R(NCO/OH), different molecular weights of PEG, DMPA, BDO and EDA on theperformance of emulsion and film were discussed in details. And then, the waterbornepolyurethane has been modified by epoxy resin (EP) in the prepolymer. The influenceDMPA content, the types and the amount of EP on the performance of emulsion and filmwere also analyzed in details.The results indicated that the prepared waterborne polyurethane emulsion showspretty appearance and excellent stability, as the prepolymerization reaction time andtemperature are respectively180min and70℃as well as the emulsification temperaturebeing30℃; Withthe increase of R and DMPA content, the tensile strength of waterbornepolyurethane film also increased and the breaking elongation tend to decrease, however,the water resistance of the film decreased with the increase of the R value and increasedwith the increase of the DMPA content. Thereby, the optimum R and optimal content ofDMPA were determined respectively as1.7and5%~7%; additionally, taking PEG asmaterial, which has larger relative molecular mass, the prepared waterborne polyurethaneemulsion appears brilliantly and shows great stability as the contents of BDO and EDAare6%~8%and2%respectively. Moreover, it was measured that the water absorption,tensile strength and breaking elongation of the film are respectively11.46%,10.46MPaand402%. Although little change happens to the appearance and stability of thewaterborne polyurethane emulsion, which was modified by EP, the water resistance,mechanical properties and thermal stability of the film show great change along with thedifferent additions of EP. According to the research, the waterborne polyurethaneemulsion shows better performance as the EP content is8%. Furthermore, theperformance of the waterborne polyurethane emulsion modified by E-44is better thanthat modified by E-51. The water absorption, tensile strength and breaking elongation ofthe film, which are modified by E-44, are respectively8.41%,15.52MPa and318%. TG analysis indicated that the thermal stability of the film, which was modified by EPsignificantly improved. Moreover, the thermal stability of the film, which was modifiedby E-44, is better than that, which was modified by E-51. According to the FTIR analysis,the EP has been successfully introduced to the waterborne polyurethane Molecular chain,and Ring-opening happened.