Electrophoretic coating, as a professional modern coating operation method, has the following characteristics:
(1) It is conducive to the realization of automatic assembly line production, the painting rhythm is fast (1~3min), and the degree of automation is high, which greatly improves the production efficiency;
(2) The thickness of the coating film is uniform. For cathodic electrophoretic paint, it is easy to adjust the voltage to control the film thickness at a certain value within the range of 10~35µm;
(3) Better coating film coverage on the edge, inner cavity and welding seam improves the overall anti-rust performance of the product coating. The layer is fully suitable for the requirements of high-end products, and the salt spray test can reach more than 800h;
(4) Safe workability. The electrophoretic paint liquid only contains less than 3% co-solvent, and water is used as the dispersion medium. There is no risk of fire, and there will be no pollution to the atmosphere from solvent emission. The electrophoresis equipment is equipped with an ultrafiltration cycle. System, so that the bath liquid is effectively used, only a small amount of ultrafiltrate is discharged occasionally, and there is no pollution of the paint liquid to the environment;
(5) The utilization rate of the paint is as high as 95%. Due to the low viscosity of the bath liquid, the amount of workpiece carried out is small and recycled by the ultrafiltration device, and the loss is extremely low;
(6) The coating film has good appearance, no flow marks, and good flatness when drying. Since the wet film only contains a small amount of water, there will be no sag phenomenon during baking, and there is no solvent vapor condensate on the coating. The redissolution effect of the film makes the coating film flat and smooth. For thick film cathodic electrophoretic paint, the flattening rate can reach up to 83%, and the intermediate coating can be omitted.
The defects of electrophoretic coating mainly include the following aspects:
(1) The drying temperature is high (180°C), the color of the coating film is single, and the weather resistance of the primer is poor;
(2) Large investment in equipment and strict management requirements;
(3) A variety of metal products are not suitable for electrophoretic painting at the same time, because their destruction voltages are different;
(4) Hangers need to be cleaned frequently to ensure conductivity, and the cleaning workload is heavy;
(5) Non-conductive products such as plastics and wood cannot be painted by electrophoresis, nor can they be topcoated on the surface of the primer;
(6) Floating workpieces such as box shapes are not suitable for electrophoretic painting.
