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Talk about the future painting technology and paint development trend

talk about the future painting technology and paint development trend

March 28, 2013

[China paint information] painting materials, painting process, painting equipment and painting management are the four elements of automotive painting, which complement each other and promote the progress and development of painting process and technology. The 21st century is called the new century facing the environment. Environmental protection has attracted worldwide attention and has become the most urgent research topic for mankind. The coating of automobile and its parts is one of the links that consume the most energy and produce the most three wastes in the process of automobile manufacturing. Therefore, reducing painting hazards, reducing painting costs and improving painting quality have always been the theme of the development of painting technology

application of new coating materials

new and adopt the current 4-octave frequency technology. The application of coating materials is the precursor of coating technology progress. On the premise of continuously meeting the requirements of coating performance, the main development goal is always to apply materials that can reduce public hazards and reduce coating costs

degreaser prepared by biodegradable activator, nickel free phosphating solution, nitrite free phosphating solution, chromium free passivator, low temperature degreaser (treatment temperature 43 ℃), low temperature (35 ℃) less slag phosphating solution with the same performance as the routine (10% - 30% lower than the routine), lead-free tin free cathodic electrophoretic coating and low temperature curing (160 ℃ 10min), low heating reduction (less than 4%) Cathodic electrophoretic coatings with low VOC volatilization (0.4% - 0.8%) have been widely used in Europe, America and Japan for many years. In North America and Europe, the secondary electrophoretic coating that can replace the traditional medium coating has been applied

in Europe, some automobile companies have adopted all water-based coatings on new coating lines in recent years, and the VOC emission has been lower than the 35g/m2 required by the regulations (TA Luft, Germany, 1995). Since the 1990s, electrophoretic primer or powder coating has been used for the primer of all new coating lines, water-based coating or high solid materials for the intermediate coating, and water-based primer and high solid varnish for the finish. At present, powder varnish has been applied to car body coating. After the industrial application of powder finish paint, the powder metal base color has also been commercialized. In North America, powder intermediate coating has been industrialized and stratolaunch has completed an independent application for many years. At the same time, the base color of water-based topcoat has been popularized very quickly in recent years, and the application of high solid intermediate coating and topcoat is also quite common. The application technology of ultraviolet (UV) curing coatings in automobile coating in Europe and America is close to maturity. Japan is also actively developing and promoting water-based coatings, high solid and ultra-high solid sub gloss coatings

with the continuous deterioration of the global environment, we must greatly improve the acid rain resistance and scratch resistance of automotive coatings. In recent years, electrophoretic coatings with high penetrability and low pigment content, acid rain resistant and scratch resistant topcoats, multi-color intermediate coats and coatings using viscosity control technology that reduce the thickness difference of electrophoretic primer film on the inner and outer surfaces of vehicle bodies have been widely used. The application of pretreatment materials and electrophoretic paint in several major automobile companies in China is not much different from the international level, but because the application of water-based intermediate coating and water-based topcoat must use special equipment, the coating cost is increased. Although wholly foreign-owned enterprises and joint ventures have the ability to produce water-based intermediate coatings and water-based topcoats in China, the traditional solvent based coatings with medium and low solids are still used in automotive intermediate coatings and topcoats, and the VOC emission of coating is far behind that of Europe

coating process and equipment

in recent ten years, the progress of coating process and equipment is mainly reflected in the application of environmental friendly coating materials, reducing the discharge of wastewater and waste residue, reducing costs, optimizing the automobile production process and so on. Due to the progress of coating materials, the design of body coating system has also made revolutionary progress. Several typical new coating systems and new technologies have been or will be used in industrial production. The current coating process and equipment in China are generally equivalent to the level of Europe and the United States 10 years ago. Some enterprises have adopted some new equipment of today's international advanced level in the new coating line

apply a thin layer of molybdenum disulfide grease 1 regularly Water saving and waste recycling technology

pretreatment and electrophoresis are the links with the largest water consumption and wastewater discharge of automobile coating. With the continuous maturity of membrane technology, membrane separation technology (UF and RO) is used to recover degreasing liquid, regenerate cleaning water and pretreatment wastewater, making it possible to realize the real closed-circuit cleaning of electrophoresis. At present, membrane separation technology has been applied

in recent years, with the industrial application of environmental protection coatings in developed countries, some coating recycling technologies (such as powder slurry recycling technology, powder primer and varnish recovery technology, waste paint flocculation dryer technology, ultrafiltration, cooling and electrostatic adsorption recovery of water-based paint technology, water-based paint recovery technology after spray painting fog, etc.) have also been applied, so as to further improve the coating utilization rate of the coating line, Minimize the discharge of waste paint residue

at present, China does not pay enough attention to coating water saving and comprehensive utilization of three wastes, and is relatively backward in the application of new technologies

2. Several new body coating processes

reverse process process: spray powder coating on the outer surface of the body first, and then conduct electrophoretic coating after hot melting, and then dry the powder/electrophoretic coating together. Using this process, the amount of electrophoretic coating can be reduced by about 60%, and the thickness is 70 μ M powder coating replaces the electrophoretic primer and intermediate coating on the outer surface of the car body, and cancels the intermediate coating and drying processes, so as to save material and energy costs and reduce VOC emissions

secondary electrophoresis process: two coating electrophoresis materials are used, and the second layer of electrophoresis (35 ~ 40 μ m) Replace intermediate coat. The automatic construction of electrophoresis process is stable and reliable, with high one-time qualification rate, high material utilization rate and less equipment investment (no air conditioning system is required), so 48% of the cost can be saved, and the maintenance frequency and the paint slag and VOC emission of traditional intermediate coating can be reduced

integrated coating process (three coating concept): use the functional layer with the same color as the top coat (15 μ m) Instead of intermediate coating, there is no need to dry between the functional layer and the bottom color of the topcoat, and the intermediate coating line is cancelled, which greatly reduces VOC emissions while improving production efficiency

3. Film coating technology replaces the coating of plastic covering parts

film coating technology is a kind of prefabricated top coat film suitable for hot forming. The performance and appearance of the top coat of the product after hot forming are very similar to the traditional baking spraying film. This technology is mainly used in the production of plastic parts. The prefabricated composite coating is formed and fused with the plastic parts at the same time of casting and forming by using the "sandwich molding" or "internal molding" process, so as to obtain a defect free coating cover. The body frame is manufactured by the traditional stamping and welding process. The painting workshop only paints the body frame, and the finish coat adopts the powder spraying technology. Due to the small exposed area of the body frame, the color of the finish coat does not have to be the same as that of the covering parts, and one kind of depth is enough. Large area covering parts are plastic parts made by coating technology, with thousands of colors. This greatly simplifies the body coating process, reduces the coating cost, and makes the VOC emission of coating reach about 7g/m2, which is far lower than the requirements of European emission regulations

4. Body painting p2zero concept

the so-called p2zero concept is a zero emission paint workshop. On the premise of meeting stringent environmental protection requirements and user quality requirements, reduce the cost of three wastes treatment, reduce the operating cost of paint workshop and simplify the paint process. The anti-corrosion primer of the steel plate of the car body is applied before the parts are made. The car body entering the paint workshop does not need to be painted with primer, but only one layer of powder base color and one layer of powder finishing. Therefore, the process waiting time can be minimized, the traditional paint mixing room can be cancelled, the process adjustment can be more flexible, the anti rust process can be cancelled in the production process from the steel plate to the car body before painting, and the problem of poor anti-corrosion of the traditional coating weld and cavity structure can be completely eliminated Save the area of coating workshop, reduce the cost of three wastes treatment, no paint slag system and waste paint treatment system, no exhaust in paint booth, air pollution and solid waste tend to zero, no liquid discharge, paint manufacturing and use efficiency greater than 95%, no odor and no danger

5. Painting of chassis parts

in developed countries, phosphating, cathodic electrophoresis or powder spraying processes are widely used for the painting of chassis parts. Generally, the parts of large assemblies are first electrophoretic or powder sprayed, then assembled, and then sprayed with low-temperature or room temperature curing surface paint as required. Due to the good mechanical properties of cathodic electrophoresis and powder coating, some parts can be machined after coating, so as to avoid corrosion of parts due to long processing time before coating. Most parts of frame and chassis are hot-rolled plates and castings. Shot blasting or sand blasting is often used before forming or painting, and pickling treatment has been gradually eliminated

at present, the production scale of parts coating in China is generally small and relatively backward on the whole. Cars and other small passenger cars are relatively good, and the painting process and coating level of trucks, passenger cars and agricultural transport vehicles are not high

6. New coating conveyor

at present, the typical conveyor used in the pretreatment and electrophoresis of the body coating line in China are push rod suspension chain, swing rod chain and program-controlled hoist. They have their own advantages and disadvantages. The common disadvantage is that they can not solve the effective exhaust problem in many cavity structures inside the car body, especially the air bag problem in the roof cover. These parts cannot be phosphated and electrophoretic treated. After the birth of the new multi-function shuttle (vario shuttle) and rodip, these problems have not only been solved, but also all the advantages of the aforementioned transport aircraft have been inherited

the multi-function shuttle machine also has the function of realizing multiple varieties and different processes in one production line, which fully meets the requirements of automatic flexible coating production. These two kinds of conveyors have been applied in the newly-built body painting line in China

7. Improvement of the structure and function of other coating equipment

in Europe, the structural materials of coating equipment are mainly stainless steel, and the electrical circuits of the equipment are designed in the equipment structure, eliminating the electrical pipelines, the modular design of the equipment and the three-dimensional zoning layout of the workshop, so as to ensure the high-definition cleanliness of the coating to the greatest extent, which is a far-reaching requirement and safety and fire prevention requirement for the industry to develop high-quality and high-value goods. The new generation drying room without external air duct and internal radiation enhanced convection has greatly improved the thermal efficiency and the uniformity of drying temperature. With the progress of robot technology, the automatic body painting machine is gradually replaced by multi degree of freedom painting robot. Robot automatic operation is widely used in painting and sealing, which is more suitable for flexible production than painting machine. Non metallic materials are widely used in mechanized transmission chains to greatly reduce transmission noise

coating management

coating management includes the ordering of coating materials, material quality control and construction process control. Due to the wide variety of materials used in automobile coating, easy to deteriorate in the process of storage and transportation, long process flow, and many parameters that need to be controlled, its complexity is the highest in automobile production management. In developed countries of automobile industry, the development of automobile coating materials has promoted the progress of automobile coating technology. In order to reduce the coating cost, the supply mode has also changed from single material supply to system supply. The system supply mode began in the early 1990s and has been basically popularized in Europe and the United States. Major automobile manufacturing enterprises in the world have always attached great importance to coating management, and coating manufacturers are directly responsible for coating

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