Preparation,structure and properties of biomass modified cathodic polyurethane electrophoretic paint
Hydroxyl-terminated cationic waterborne polyurethane resin modified by urushiol was prepared by stepwise polymerization method,after mixed auxiliaries,and then cathodic electrophoretic paint was obtained.The effects of urushiol contents on the structure and properties of the polyurethane (PU)were investigated by Fourier transform infrared spectroscopy(FT-IR),X-Ray Diffraction(XRD) and thermogravimetric analysis(TGA).The results showed that the modification of urushiol on the PU resin improved micro-phase separation of PU,and the order degree of hard segment in hard phase. With an increase of urushiol in content,the performance of the film showed the law of increasing first and then decreasing.When the molar ratio of urushiol to 1,4-butanediol(BDO)reached a proper value of 1:14,the glossiness,hardness,acid resistance and solvent resistance for the film w ere desired.T he glossiness reaches the value of 130,the hardness is about 5H,the acid resistance is around 43 h,and ac-etone wiping times are about 748 times.The modification of urushiol on the PU resin improves the thermal stability of the polyurethane film.
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