The resin contained in the cathodic electrophoretic coating has basic groups, which become salt after acid neutralization and dissolve in water. After the direct current is applied, the acid radical negative ions move to the anode, and the resin ions and the pigment particles wrapped by them move to the cathode with positive charges and deposit on the cathode. Electrophoresis coating is a very complex electrochemical reaction. It is generally believed that at least four effects of electrophoresis, electrodeposition, electrolysis, and electroosmosis occur simultaneously.
Electrophoretic paint film has the advantages of fullness, uniformity, flatness and smooth coating. The hardness, adhesion, corrosion resistance, impact performance, and permeability of electrophoretic paint film are significantly better than other coating processes.
(1) Water-soluble paint is used, water is used as the dissolving medium, which saves a lot of organic solvents, greatly reduces air pollution and environmental hazards, is safe and sanitary, and avoids the hidden danger of fire;
(2) The painting efficiency of electrophoretic painting process is high, the paint loss is small, and the utilization rate of the paint can reach 90% to 95%;
(3) The coating film thickness is uniform, the adhesion is strong, and the coating quality is good. Each part of the workpiece, such as the inner layer, depressions and welds, can obtain a uniform and smooth coating film, which solves the problem of other coating methods for complex-shaped workpieces;
(4) The production efficiency is high, and the construction can realize automatic and continuous production, which greatly improves labor efficiency;
(5) The equipment is complex, the investment cost is high, the power consumption is large, the temperature required for drying and curing is high, the management of paint and painting is complicated, the construction conditions are strict, and wastewater treatment is required;
(6) Only water-soluble paint can be used, and the color cannot be changed during the coating process. The stability of the paint is not easy to control after storage for a long time.
(7) Electrophoretic coating process equipment is complex, high-tech content, suitable for fixed color production.