Epoxy cathodic electrophoretic paint film is tough, good chemical resistance, strong corrosion resistance, suitable for primers, but the disadvantage is hard and brittle, leading to poor flexibility and low gloss of this kind of products. Acrylic cathodic electrophoretic paint has excellent properties of light retention, weather resistance, ultraviolet aging resistance and high decoration, etc. It is widely used in the integrated electrophoretic coating of underside, but it has disadvantages such as poor heat resistance and wear resistance. Polyurethane cathodic electrophoretic paint prepared by aliphatic isocyanate has high hardness, transparency, good chemical resistance and uv resistance. In addition, the polyurethane cathodic electrophoretic coating can eliminate the influence of filamentous corrosion and scar corrosion on the decorative appearance of the coating. The good flatness of the electrophoretic coating gives the coating higher fullness. However, due to the strict process conditions, the construction is prone to defects such as spots, water marks, rough coating film, pinholes and locking edges.

       Researchers from Qingdao University of Science and Technology prepared the cathodic polyurethane electrophoretic resin with butanone oxime sealant, and optimized its electrophoretic process to obtain the paint film with better performance and properties.

       Cationic polyurethane electrophoretic resin was synthesized by self-emulsification using oligomer dihydric alcohol and isoferone diisocyanate (IPDI) as main materials. The effects of electrophoretic parameters, type and amount of film-forming auxiliaries, type of soft section and neutralization degree on the film performance were investigated. The results showed that the emulsion temperature was 30℃, the electrophoretic voltage was 60V, the propylene glycol phenyl ether (PPH) accounted for 5% of the resin mass fraction, the polytetrahydrofuran ether diol (ptmg-1000) was the soft segment, the neutralization degree was 85%, and the paint film with excellent appearance and performance was obtained.