The electrophoresis coating production line is composed of a large number of electrophoresis equipment. Small-scale manual electrophoresis lines mainly include: electrophoresis tanks, electrophoretic paint ultrafiltration machines, electrophoresis power supplies, hot and cold exchangers, pure water machines, circulating filtration systems, and cleaning water tanks. If it is an automatic coating line, there are also supporting automatic transmission devices and control cabinets.
Electrophoresis coating equipment is composed of electrophoresis tank, circulation system device, paint filter device, temperature control device, paint management device, DC power supply device, water washing device after electrophoresis coating, ultrafiltration device, baking device, pure water equipment, etc. . The price of electrophoresis equipment ranges from tens of thousands to hundreds of thousands, mainly based on customer needs. The larger the workpiece, the larger the investment in production capacity is relatively high, otherwise the investment is small.
The role of electrophoretic paint co-solvents in electrophoretic coatings is roughly three points:
1. It has a solubilizing effect on the electrophoretic paint resin. The process is divided into three stages of penetration, swelling, and dissolution. The size of the solubilizing effect depends on the structure and polarity of the co-solvent and the electrophoretic coating resin.
2. It can improve the stability of the bath liquid, promote the leveling of the paint film, and improve the appearance quality of the paint film.
3. Adjustable paint film thickness. Different electrophoretic coatings have their own co-solvents, and the composition and ratio of co-solvents are specified within a certain range of adaptation. This is an important guarantee for the long-term and stable appearance of the paint film.
The content of electrophoretic co-solvent has a great influence on the quality of electrophoretic coatings. The content of co-solvent decreases, the thickness of the electrophoretic paint film decreases, the dispersion of the bath liquid becomes worse, the surface becomes rough, the gloss decreases, and pinholes are liable to occur. Cosolvent increases, film thickness increases, gloss improves, but breakdown voltage decreases, Coulomb efficiency decreases, paint film adhesion and corrosion resistance deteriorate.
Excessive co-solvent content will cause the paint film to peel off, caking, and pin holes. Therefore, under the premise of ensuring film thickness and coating quality in the application, the lower the co-solvent, the better, in order to improve the electrophoretic voltage and the quality of the paint film. Good electrophoresis should control the cosolvent content below 1.5%, but in the case of a long update period, the paint film is thin and the leveling property is not good, the cosolvent content can be appropriately increased.
The new generation of cathodic electrophoretic coatings should have the following characteristics:
A. The transmissivity of the new-generation cathodic electrophoretic coating should be further improved. The higher the swimming penetration rate, the more uniform the film thickness inside the vehicle body, thereby improving the overall corrosion resistance of the vehicle body, reducing the construction voltage, and reducing the amount of paint.
B. Improve edge corrosion resistance. In the process of electrophoresis, some edge parts are particularly thin due to the electrochemical action of the coating, so that corrosion easily occurs here, and the corrosion resistance is improved by improving the performance of the coating.
C. Reduce Yankee Ratio. Yankee ratio is the ratio of pigment to resin in the coating. Decreasing it can increase the content of resin, improve the fluidity of the coating, reduce the settling rate of colloid, reduce pigment flocculation and protect the pump, and reduce material consumption.
D. Reduce the amount of solvent. The higher the solvent content, the greater the environmental pollution, which is not conducive to work. Lowering it helps protect the environment and save investment.
E. Lead-free and tin-free, more environmentally friendly. Lead plays an important role in anti-corrosion catalysis, passivation, and accelerated cross-linking of electrophoretic coatings, but lead-containing pigments have a great effect on the anti-corrosion of bare steel plates, and lead itself is a very toxic element. Its restrictions are severe. The performance of tin is similar to that of lead, and the two are usually mixed.
Limitations of electrophoretic paint
1. Electrophoresis can only be performed under the condition of being energized, so it is suitable for conductive objects (generally metals).
2. Electrophoretic coating technology is not suitable for coating objects made of various metals with different conductive properties. If some electrophoretic coatings are allergic to metal ions such as Cu and Sn.
3. The wet film of electrophoretic paint must be baked before it can form a dense paint film. Therefore, the objects that can not withstand high temperature cannot be electrophoretic coated.
4. The renewal period of the bottom of the electrophoresis tank is within 6 months, so electrophoresis coating is not suitable for small batch production.
5. There are differences in the performance of electrophoretic coatings on different substrates.
6. Strong technical force is required to support it, especially for color electrophoresis. To achieve the desired color effect, if you are not a professional, it will be difficult to adjust the color.
Electrophoretic paint, also called electrophoretic paint, is still used by many people. As the defects of conventional spraying continue to emerge, electrophoresis has become more and more popular. The electrophoretic paint has also been continuously updated, from anodic electrophoretic paint to cathodic electrophoretic paint, and from single-component electrophoretic paint to two-component electrophoretic paint. The development of electrophoretic paint has also promoted the development of electrophoretic coating, making more products no longer Use spray technology instead of electrophoresis.
Electrophoretic coatings, as a new type of low-pollution, energy-saving, resource-saving, protective and corrosion-resistant coatings, have the characteristics of flat coating film, good water resistance and chemical resistance, etc., and it is easy to realize the mechanization and automation of the coating industry. It is suitable for painting complex workpieces with edges and corners and holes, and is widely used for painting hardware parts such as automobiles, electromechanical products and home appliances.
1. Electrophoretic coating can realize complete mechanization and automation, which not only reduces labor intensity, but also greatly improves labor productivity, which is suitable for a large number of assembly line operations.
2. The electrophoretic coating has a high swimming penetration rate, completely dissolved or emulsified in water, and the formulated tank fluid has a low viscosity, which can easily penetrate into the bag-like structure and gaps of the coated object, and is particularly suitable for the surface coating of special-shaped conductive materials. Installed.
3. The electrophoresis bath has high conductivity. The paint ions can quickly swim under the action of the electric field. After being neutralized on the surface of the coating, an electrically neutral wet paint film is formed. As the wet paint film thickens, the resistance increases. Larger, the amount of paint particles deposited gradually becomes smaller, thus forming a uniform and fine paint film.
4. High utilization rate of coating, more than 95% or even 100%. Due to the low solid content and low viscosity of the bath, the coatings carried by the coating are less, especially the application of ultrafiltration technology. The closed cycle of the coating process is implemented, and the coating recovery rate is high.
5. The coating film has strong anti-corrosion ability. Since the electrophoretic coating is uniformly formed under the action of an electric field, the use of the electrophoretic coating method can significantly improve the corrosion resistance of the inner cavity, welds and edges of the workpiece.
6, electrophoretic coatings have low solvent content, one is conducive to environmental protection, and the other is good production safety. After 30 years of development of cathodic electrophoretic coatings, international coating suppliers represented by the United States continue to adopt new technologies and develop new products, so that electrophoretic coatings are continuously updated.
The electrophoresis process is divided into anodic electrophoresis and cathodic electrophoresis. If the coating particles are negatively charged, the workpiece is an anode, and the coating particles are deposited on the workpiece under the action of an electric field force, which is called anodic electrophoresis; otherwise, if the coating particles are positively charged, the workpiece is a cathode, and the coating particles are deposited on the workpiece as a film. Cathodic electrophoresis.
The characteristics of anodic electrophoresis are: cheaper raw materials (generally 50% cheaper than cathodic electrophoresis); simpler equipment and less investment (generally 30% cheaper than cathodic electrophoresis); low technical requirements; poor corrosion resistance of coatings compared to cathodic electrophoresis ( (Approximately 1/4 of the life of cathodic electrophoresis).
The reason for the high corrosion resistance of the cathodic electrophoretic coating is that the workpiece is a cathode, no anodic dissolution occurs, and the surface of the workpiece and the phosphating film are not damaged; the electrophoretic coating (generally a nitrogen-containing resin) has a protective effect on the metal and the paint used is expensive High quality.
Electroplating is the process of plating a thin layer of other metals or alloys on the surface of certain metals using the principle of electrolysis. Abrasion resistance, electrical conductivity, light reflectivity, and improve aesthetics.
During electroplating, the plated metal or other insoluble material is used as the anode, and the metal product to be plated is used as the cathode. The cations of the plated metal are reduced on the metal surface to form a coating. In order to eliminate the interference of other cations and make the coating uniform and firm, a solution containing the metal cations of the coating layer should be used as the plating solution to keep the concentration of the metal cations of the coating layer unchanged. The purpose of electroplating is to plate a metal coating on the substrate to change the surface properties or dimensions of the substrate.
Electroplating can enhance the corrosion resistance of metals (corrosion-resistant metals are mostly used for plating metals), increase hardness, prevent wear, improve conductivity, lubricity, heat resistance, and beautiful surfaces.
Electrophoresis is the migration of charged colloidal particles in a liquid medium relative to a liquid under the action of an external electric field.
Electrophoresis is divided into two types: cathodic electrophoresis and anodic electrophoresis. Different electrophoresis solutions require different electrophoresis solutions.
The difference between the two is that the intermediate objects are different, one is metal ions, and the other is colloid.
The results after processing are also different. Electroplating is a layer of metal to protect, rust, and aesthetic functions. Electrophoresis is generally used to coat the surface with a layer of paint, which is often used in the automotive industry.
The common point between the two is that there must be electricity, that is, positive and negative electrodes, which can form an electric field, so that ions or charged colloids can move in a directional manner.