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Heat-resistant powder coating refers to a protective powder coating that can withstand high temperatures above 200 °C for a long time, and the coating film does not change color and is not damaged, and can still maintain appropriate physical and mechanical properties. The heat resistance of silicone powder coating is relatively high, but its price is high, the initial appearance and mechanical properties are not very good, the curing temperature is high, and it is quite difficult to obtain a coating film with long-term high temperature resistance of more than 400°. Although the heat resistance of epoxy resin itself is worse than that of silicone resin, its performance is relatively comprehensive; By modifying and adding appropriate curing agents and pigments, good heat resistance can also be obtained. Therefore, heat-resistant epoxy powder coatings are widely used.   1 Performance requirements for heat-resistant epoxy powder coatings 1.1 Heat resistance Heat resistance is the most important performance index, some products may not be used at a certain high temperature for a long time, therefore, heat resistance can be divided into long-term and short-term two. According to the performance requirements of the object and other aspects, the appropriate modified epoxy resin, curing agent and pigment filler can be selected to achieve the purpose of low price and high quality.   1.2 Mechanical Properties This includes both initial and late mechanical properties. Due to the limitations in the selection of curing agents and pigments and fillers, their mechanical properties can be slightly reduced compared with the requirements of general powder coatings; However, it is important that the mechanical properties are not reduced too much in the later stage.   1.3 Anti-corrosion properties (including chemical resistance) The anti-corrosion performance of epoxy resin is relatively good, therefore, epoxy powder coating can fully meet the requirements of this aspect.   1.4 Appearance Including flatness, gloss, color and other properties. The flatness can vary depending on the object of use. In general, slight orange peel should be allowed. Gloss mostly requires a flat and matte finish, which is completely achievable. As for colors, especially light colors, it is more difficult to keep them the same at all. Antioxidants and hindered amines can be added appropriately to solve the problem.   1.5 Storage stability Since it is not a high-temperature fast-curing and the Tg of the resin is high, the storage stability should be no problem. conclusion There are many varieties of high-temperature resistant polymers, but there are still certain difficulties and problems in preparing powder coatings that can meet the requirements in all aspects. With epoxy resin, after modification and selection of appropriate curing agents and pigments, powder coatings with different high temperature requirements (200~600 °C) can be prepared. Heat-resistant epoxy powder coating can be widely used in household appliances: such as barbecue grills, heaters, high-power lighting, and high-temperature parts of mechanical equipment, such as smoke exhaust pipes, high-temperature furnaces, petrochemical plants, aircraft, missiles, aerospace equipment, etc. Heat-resistant epoxy powder coatings can also be used for the coating of electrical insulating materials. Brominated epoxy resin or appropriate flame retardant can also be used as a flame retardant powder coating.

Electrostatic spraying can give parts better appearance quality and strong environmental adaptability, and has been widely used in the coating industry. It has significant advantages over traditional painting processes: no primer, no thinner; No pollution to the environment, no toxicity to the human body; The construction is simple, and there will be no sagging phenomenon common in the painting process; The appearance quality of the coating is excellent, the adhesion and mechanical strength are high, and the corrosion resistance and wear resistance are strong; Short curing time, high production efficiency and low cost. Although the surface quality of the substrate has been fully considered at the beginning of the design structure and process of the radar parts, the coating quality is affected due to the inherent defects of the non-processed surface, the processing defects of the processing surface, and the bumps and extrusion defects caused by the transfer process, and it is necessary to fill the conductive putty.   1. The main factors affecting the quality of electrostatic spraying of parts   The main factor affecting the surface quality of electrostatic spraying is the defects of the parts themselves, which are mainly reflected in the pits formed by scratches, extrusions, bumps, rusts, spot welding, riveting, etc., as well as the sand holes, pores, loose and small knife lines exposed after machining of castings. As shown in Figure 1, some of these defects can be repaired by means of polishing and sanding, while others can only be filled with conductive putty. And because the composition of conductive putty is basically similar to ordinary putty, it also has the disadvantages of ordinary putty. The main manifestations are: poor adhesion and low bond strength; The surface is not delicate enough, the texture is poor, and the toughness is lacking; It is easy to pulverize after moisture; After a certain period of time, cracking, peeling, and falling off will occur. In addition, the skill level of the operator, the quality of the electrostatic powder, the performance of the equipment, the operating environment, the processing process, etc., will also affect the quality of the electrostatic spraying of parts. 2. Idea and comparative test to improve the performance of conductive putty   Analyzing the above many factors, most of them can be effectively solved by modifying the design, improving the process, operating training, improving facilities, meticulous turnover, etc., only the performance of conductive putty can not be controlled. Because it must have good conductivity, excellent adhesion, strong filling, high temperature resistance of 180 °C and other characteristics, and the conductive putty currently sold on the market is difficult to fully meet the use environment and technical requirements of existing products. To this end, the author has made some attempts and comparisons in long-term production practice, hoping to improve the performance of conductive putty through some technical means.   2.1 The method to improve the performance of conductive putty First, consider using a finished conductive putty. However, commercially available conductive putty often has poor conductivity, low powder rate, and unsatisfactory coating effect. So can a certain proportion of conductive material be added to the conductive putty to improve its conductivity and powder rate?Second, consider adding a conductive material to the adhesive so that it is both fillable and conductive. But when a conductive material is added to the adhesive, it will definitely destroy its adhesion and reduce its adhesion, so how much will this affect the coating?In addition, consider using acetone to adjust the paint into a powder slurry and then apply it to the defect with a brush. But the question is whether the paint will blister under high temperature baking after containing a certain amount of acetone?   2.2 Test protocol According to the above ideas, three schemes to fill the defects were designed by using the existing materials:(1) Add an appropriate amount (5%~10%) of aluminum powder after fully stirring the commercially available conductive putty to improve its conductivity. If it is a two-component putty, it needs to be scraped as soon as possible, and it must be used up within the gel time to avoid thickening and agglomeration.(2) Choose a variety of adhesives with good resistance to media (such as oil, water, acid, alkali, etc.), strong adhesion to metal, low temperature drying, high temperature use, non-toxic, and cheap adhesives to add conductive aluminum powder.(3) Take the powder used in the workpiece and mix it into a powder slurry with acetone. It should not be too thick to avoid leaving brush marks; It should also not be too thin, otherwise the solids content is too small to fill the defect. Generally, it is more appropriate to control the solid content at 60%~65%, and then apply the brush to the defect with a brush and bake it in an oven at 180°C for about 30min.   2.3 Test Results According to the above three schemes, the comparative test of electrostatic spraying was carried out on some specimens with similar surface defects.Test process: degreasing, rust removal→ drying→ putty-coating→ drying→ grinding→ soot blowing→ powder spraying → curing.After adding a small amount of aluminum powder to the commercially available conductive putty, the adhesion between the putty and the workpiece decreases significantly, and the increase in solid content makes it difficult to scrape, while the conductivity is slightly improved but still not ideal. Although the putty prepared with adhesive has good conductivity, the adhesion is poor, and due to the addition of a certain amount of aluminum powder, the putty prepared has the phenomenon of pulverization, which is prone to cracking, blistering, falling off, etc.The filling property of the putty made by scheme 3 is too poor, and it needs to go through many times of "brushing→ spot coating→ baking → grinding" to achieve the filling effect, although the conductivity is good, but the blistering is serious.It can be seen that all three options are not ideal. After careful analysis, it is believed that the main reason for the coating defects is that the inherent physical and chemical properties of the original material have been artificially changed, and although the conductivity effect has been improved, the adhesion, delicacy, and operability are obviously damaged, so we can only seek a breakthrough from the physical aspect.   3. The method of making self-made conductive putty with powder coating Recalling that when grinding and reworking some sprayed workpieces, it was found that the original defects such as small pits, cracks, and sand holes on the surface of the workpiece were often not as obvious as before. Could it be that the coating that is not easy to sand off at the defect plays the role of putty? Therefore, it was considered to use the molten powder coating directly as a conductive putty.   3.1 Filling of defects such as sand holes and knife lines in large areas In order to achieve the best filling effect, a thicker coating must be obtained at the defect, and preheating the workpiece can significantly increase the thickness of the powder coating, as the resistance of the powder tends to decrease as the temperature increases. When the temperature of the workpiece increases, the amount of charge neutralized by the powder through grounding discharge will increase accordingly, and the charge accumulation will be reduced, so the powder layer can be adsorbed thicker. In actual operation, the workpiece is often preheated first, and then thermal spraying, and then polished with tools such as grinding machines and polishing machines, and grinding until the non-defective parts are faintly exposed to the bottom layer of the metal, and the powder coating left by the defective places plays the role of putty.   3.2 Filling of local defects The overall grinding amount of the workpiece is large after spraying, and the powder coating is seriously wasted, so the scattered small area defects should be partially filled with powder. First of all, the workpiece should be preheated, and the preheating temperature should be 20~30°C higher than the normal curing temperature of the powder coating. Make the defect surface level upward, immediately scoop the powder with a small utensil such as an ear picker, and pile up locally at the defective place, and strive to be accurate when stacking, and try not to exceed the defect range too much, as shown in Figure 2. The powder used should be of the same brand, model, color and batch as far as possible with the powder to be sprayed at the end.Immediately afterwards, the workpiece is placed horizontally in the oven. In order to avoid the aging of powder coating caused by multiple baking, the baking temperature should be 20~30 °C lower than the normal curing temperature of powder coating, and the baking temperature should be about 15min. If it is a sand hole of a casting, the workpiece should be taken out after baking for about 10min, and a small scraper should be used to scrape the molten powder to squeeze it into the depths of the sand hole to exhaust the air, so as to avoid bubbles after the final overall spraying, and then put the workpiece into the oven to continue to solidify after scraping. After curing, the workpiece is cooled and sanded with 240# abrasive cloth. If the defect is not even, repeat the above process once. Since this method is mainly suitable for workpieces with small defects such as spot welding, sand holes, scratches, etc., it is usually enough to fill the defects with 2 times of composting.   Repeated tests under different types, different brands, different colors, different gloss, different temperatures and other conditions show that the method of local accumulation of powder coating at the defect of the preheated workpiece has good filling, good repair effect on various fine defects, and good conductivity, excellent powder absorption, uniform powder loading during the overall spraying, and does not affect the performance of the final powder coating film.    

preface Powder coating is a solid powder synthetic resin coating composed of solid resin, pigments, fillers and additives. Unlike ordinary solvent-based paints and water-based paints, its dispersion medium is not solvent and water, but air. It has the characteristics of no solvent pollution, 100% film formation, and low energy consumption. There are two main categories of powder coatings: thermoplastic and thermoset. Powder coating is a completely different form from general coating, and it exists in the state of fine powder. Since no solvents are used, it is called powder coating. The main characteristics of powder coating are: harmless, high efficiency, resource saving and environmental protection.   Application of powder coating in the new energy industry   01 The trend of "paint to powder" and "water to powder". In recent years, powder coating and coating, as a hot category of green industrial coating, has been widely used in all walks of life, especially in the application scenarios of new energy batteries, energy storage, photovoltaic fields, etc., with excellent insulation performance, ultra-high weather resistance and high temperature resistance is rapidly expanding the market in related fields. Powder coating, with its significant advantages of being able to come out of the box and suitable for automated coating, is even more outstanding in many green coating categories. Powder coating is the most cost-effective option based on the quality of the coating film, the wide range of requirements for on-site construction conditions, and the comprehensive coverage of the coating function.   02 New energy vehicles and three-electric systems At present, the mainstream packaging material PET blue film of battery cells cannot meet the requirements of the new generation of power battery structure, which brings great opportunities for the development of insulating powder, UV insulating coating, and UV insulating inkjet. At present, the internal insulation coating of the power battery liquid cold plate is mainly based on powder coating, and the current emerging technologies mainly include: electrophoresis, powder, PVC anti-stone chip coating baking, electrophoresis, powder baking, electrophoresis, polyurea baking 1, the latter two types of technologies are the latest direction, and have been applied in many new energy vehicles and battery companies. In the future, in the field of new energy, the market demand for powder coatings is still very broad. Insulating powder coatings and low-temperature powder coatings are supplied to a number of new energy vehicle companies, and are widely used in the protection of battery trays, liquid cold plates and other parts, and in new energy vehicles, automotive metal parts and plastic parts, commercial bodies and frames, it can solve the problem of edge coating falling off in the coating process of these special-shaped parts, and the performance indicators include impact resistance, breakdown resistance, insulation, water resistance, corrosion resistance and other excellent performance.   03 Energy storage applications As the underlying supporting technology of the energy storage industry chain, powder materials have made continuous breakthroughs in key fields such as cathode and anode materials, solid-state electrolytes, and hydrogen fuel cell catalysts through microstructure design, surface modification, and large-scale preparation process innovation, and have become the core elements to promote the iteration of new energy technologies. There are differences in the impact of corrosion factors in diverse energy storage application scenarios, which also puts forward requirements for the corrosion prevention of outer coatings. Relevant researchers in the industry pointed out that if the base material of energy storage is hot-rolled steel plate, its anti-corrosion mainly depends on the subsequent coating process. It can be strengthened by electrophoretic powder spraying process, or selected as a pure/high fluorinated resin system powder coating. Not only the coating, but also the coating process also affects the anti-corrosion effect. Compared with the paint process, the powder process has the characteristics of "low input, low pollution, low consumption, low cost and high efficiency". For energy storage battery modules, busbars, shells and other components, the company has developed corresponding insulating powder materials. With the application of powder coating process, the intellectualization of coating equipment continues to advance.   With the support of policies, new energy coating is more inclined to "4E" environmentally friendly green coatings With the continuous support of the state for environmental protection policies, the powder coating technology in the supporting industry of new energy vehicles is developing rapidly. In the field of coating, powder coatings are widely recognized by the market as "4E" environmentally friendly green coatings because of their characteristics of no pollution, zero VOCs emissions, high recycling rate, simple coating process and high automation. This coating not only reduces VOC emissions, but also reduces the carbon footprint of the product lifecycle. Type 4E Green Paint provides green coating protection for automotive batteries, wheels, frames, under-the-hood parts (such as radiators and shock absorbers), car bodies and various parts (joysticks, reflectors, wipers, etc.). Therefore, the development of powder coating technology can not only promote the development of the new energy vehicle industry, but also an important way to achieve environmental protection and sustainable development. Compared to liquid coatings, powder coatings offer advantages in many areas due to their superior protective properties, sustainable quality and higher transfer efficiency, especially in terms of toughness and scratch resistance. With the rapid development of the automotive track, powder coatings are also constantly pursuing performance improvement and optimization, and are committed to improving the performance of weather resistance, low temperature, film and decoration. The good flexibility, impact resistance, scratch resistance, waterproof and flame retardant properties of powder coating can effectively avoid fire hazards caused by aging of new energy vehicle parts, external collisions, extreme weather and long-term high loads, and ensure the safety of life and property of drivers and passengers. At the same time, the concept of energy saving, emission reduction, intelligence and lightweight in the automotive industry is deeply rooted in the hearts of the people, and powder coatings in the automotive field are bursting out with huge potential. The transportation industry, which accounts for about 1/3 of the total carbon emissions, has begun to implement the development strategy of new energy vehicles. Compared with traditional coatings, one-time spraying molding, the coating is lighter and thinner, saving the amount of paint and the spray coating can be recycled, with a recovery rate of 99%, improving spraying efficiency, reducing production costs, and providing environmental protection coating solutions that reduce costs and increase efficiency for the new energy vehicle industry.

Since the 80s of the 20th century, powder coatings have been increasingly recognized by the coating and coating industry as a kind of environmentally friendly coatings. Especially in recent years, the demand for environmental protection and sustainable development has risen rapidly. Whether from government regulations or industry trends, low volatile and non-volatile coatings will become the main direction of the overall development of the coating industry. However, with years of development, many disadvantages of powder coating have always plagued practitioners, the most important of which is the dispersion of materials. Dispersion is an ever-familiar problem in the coatings industry, and powder coatings have poor material dispersion. The main reason is that there is no solvent in the coating, and the extrusion mixing and dispersion is carried out under molten conditions and in a short time. The particle size, viscosity, absorption and other indexes between materials are very different, and it is difficult to achieve adequate wetting, coating and mutual miscibility. Although great improvements have been made in terms of process and system viscosity, there is not much improvement in coating performance. In recent years, some pretreatment composites have appeared, pointing to another way out in this regard, making there are more options for improving the performance of coatings.   Application of surface coating technology   Such raw materials are more common, such as the coating of metal powders, pigments, fillers, etc., and the selection of different coating materials can bring better performance. The outer layer of aluminum powder coated with silica or acrylic acid can effectively improve its oxidation resistance, and the outdoor use of aluminum powder is possible under the multi-layer coating. The latest polyester-coated aluminum powder relies on the outer coating to be more similar to the primer, and avoids the shortcomings of large oil absorption and the difference between the charged and the primer. In the case of only using post-mixing, the amount is increased, and there is no separation between the metal powder and the base powder, and the metal powder effect is good. At the same time, the flash point of aluminum powder after multi-layer coating has also been reduced accordingly, so that the safety of its use has been improved. By coating different organic materials on the surface of the filler, the functional filler can effectively reduce the oil absorption of the filler and adjust the leveling and gloss of the coating after use. The pearlescent coated with stearic acid can get a better shimmering effect in the coating and reduce its dosage. The calcium carbonate coated with different organic compounds also greatly improves the surface state on the premise of improving its stability, and has been applied in many fields. The dispersion of pigments has always been the most important process in the coatings industry. How to effectively destroy the agglomeration between small particles of pigments and make them stably dispersed in the coating system is also the focus of research by pigment and equipment manufacturers. Powder coatings are very different from other types of coatings in this respect, with overly simplistic processes and very large viscosities that make pigment dispersion more macroscopic. The role of functional material structures The core of the pearl determines the degree of its scintillation, and there are natural silicon to artificial silicon and then glass pearl, and we can get different changes. Similarly, a change in particle size can improve the dry powder flow of the powder while providing the material function. These are some of the effective applications of physical states in powders. When making high-hardness products, we generally choose two ways: surface hardening and physical hardening. The most common in physical hardening is silicon, and the Mohs hardness of quartz can reach 7.5, but we ignore another high hardness substance, that is, corundum with a hardness of 9 on the Mohs scale, and China's corundum reserves are very large. The main component of corundum is A1203, from the white corundum used in aluminum smelting to the most slag black corundum, and how to effectively improve the dispersion of corundum in the coating is the key to its application. High-temperature calcination of alumina monohydrate with a particle size of less than 5 microns can obtain corundum particles with a porous structure. On the premise of increasing the specific surface area of the particles, the adhesion between the particles and the resin can be improved. The use of a slightly lower viscosity curing system allows for more thorough wetting of the system. When the addition amount of this kind of hardening seasoning reaches 40%, the surface pencil hardness of 5H-6H0 is determined according to the wear resistance of GB/T 1768-2006 paint film, 1kg positive pressure, and the mass loss of 10,000 cycles can be controlled between 100~200mg.

Thermosetting powder crackle paint not only has many advantages of thermosetting powder coatings, but also forms beautiful crackle patterns after application, which are natural, elegant, and rustic, and can be adjusted according to the shape of the work and the size of the cracks. This type of powder coating can be widely used in the painting of toys, crafts, and architectural doors and windows. Powder crackle paint utilizes changes in the melting viscosity, surface tension, and curing speed of the powder coating during baking to cause shrinkage on the coating surface, resulting in a crackle effect. The typical methods to create cracks include increasing the amount of filler or reducing the amount of base material, generally choosing fillers with high oil absorption to hinder the normal flow of resin during film formation; this prevents the resin from fully enveloping or just perfectly covering the pigment and filler particles, leaving no excess resin to fill the gaps between the pigment and filler particles, thus forming a three-dimensional structure with the pigment and filler as the framework, and exposing the color of the primer at the cracks. Precautions for powder crack coating construction (1) During the powder coating process, it is important to ensure that the powder coating on the surface of the metal workpiece is applied evenly, with a uniform and suitable thickness. If it is too thick, it may cause unclear crack boundaries; if too thin, issues such as exposure of the substrate and pinholes may occur. (2) It is recommended to spray in sequence from high to low. First coat the secondary surfaces, followed by the primary surfaces, and it is best to complete the spray in one go. Some hard-to-reach areas may require local touch-ups, which can make the existing cracks disappear. (3) To achieve the best spraying effect, before construction, the materials should be screened through a sieve that is slightly larger, and the powder supply system in the fluidized bed should adjust various process parameters such as powder air pressure, atomization air pressure, the distance between the nozzle and the workpiece, and the movement speed of the spray gun for optimal results. (4) When using powder crackle coatings, it is important to prevent contamination by other types of coatings. If conditions permit, it is best to have two sets of equipment for separate use. (5) When using electrostatic spraying, the thermal spraying of the workpiece produces better texturing effects than cold spraying. This is because, during thermal spraying, the powder coating melts quickly upon contact with the workpiece, and the coating immediately starts to convect (if containing metallic pigments, the pigments will float), allowing enough time to rotate to the best reflective angle. In contrast, cold spraying takes a longer time for the workpiece's heat capacity to raise the temperature from room temperature to curing temperature, which means that for an extended period, the resin remains at high viscosity, hindering the formation of texture due to internal resistance. If the gelation time of the coating is short, it will gradually gel during the heating process, and when it reaches the curing temperature, the coating will have already formed a gel, making the formation of texture impossible. Common problems with powder crackle coating (1) Running: Powder coating with cracks is caused by the coating film being too thick during spraying; another reason may be that the heating rate is too slow, leading to an excessively long gelation time for the powder coating. The solution is to control the film thickness and speed up the heating rate. Of course, it is also possible that the melting viscosity of the powder coating itself is too low, causing running. (2) Uneven cracking: If the spray gun's movement speed is uneven during the spraying process, the thickness of the coating film will be inconsistent, thus it is essential to strictly control the manual process during spraying to achieve uniform and beautiful cracks. (3) Exposing the substrate and pinholes: Poor surface preparation of the workpiece leads to the surface adhering to substances with surface tension (such as oil or spots), or the compressed air contains oil or water. The solution is to strictly control the quality of the workpiece before spraying. Of course, severe substrate exposure may occur when spraying this powder coating too thinly. (4) Others: Such as when the impact strength and adhesion of the coating film are poor, the curing temperature is too low, the time is too short, the coating is too thick, or the phosphating film is poor or too thick, or insufficient pretreatment, etc. Conclusion The production process of crackle powder coating is simple, with stable quality performance and excellent decorative properties, and it has been widely used for painting general metal surfaces. Due to its uniqueness, crackle powder coatings are suitable for various systems, and with the further development of powder coatings, research into crackle powder coatings has become very valuable. The application of crackle powder coatings is straightforward, easily creating patterns that are evenly distributed, making it an ideal high-decorative powder coating. I firmly believe that crackle powder coatings, with their novel decorative effects and reasonable pricing, will be favored by a wide range of users.

At the beginning of 2025, China's construction machinery industry ushered in a "good start". In February, domestic excavator sales reached 11,640 units, a year-on-year increase of 99.4%, the highest growth rate in the same period since 2019; The sales of graders, forklifts, aerial work platforms and other equipment have soared across the board, and the operating rate of equipment in many places has exceeded 50% (data source: China Construction Machinery Industry Association). Under the superposition of infrastructure investment and equipment renewal cycle, the construction machinery market as a whole is showing a rebounding trend. The wave of equipment renewal not only drives the demand for the coating of the whole machine, but also accelerates the green transformation of the industry through the substitution of environmentally friendly materials. Driven by the "dual carbon" goal and industrial upgrading, powder coating has jumped from an auxiliary material to a key link in the construction machinery value chain. Coating, is an important process in the production of construction machinery products, the large-scale development of the construction machinery industry at the same time, a large number of construction machinery consumes a large number of coatings, environmental pollution of the traditional solvent-based coating process has not adapted to the environmental protection needs of the new era. The "Limit of Hazardous Substances in Industrial Protective Coatings" (GB 30981-2020) published by the Standardization Administration of the People's Republic of China puts forward limit requirements for harmful substances such as VOCs content in construction machinery coatings. This measure demonstrates the country's determination to win the "blue sky defense war", and also points out the direction of green transformation for the construction machinery coating industry. Compared with traditional solvent-based coatings, WANAN construction machinery powder coatings have the advantages of solvent-free and pollution-free environmental performance. In the "Technical Requirements for Coating Products with Low Volatile Organic Compound Content" (GB/T 38597-2020), it is clarified that powder coatings are coating products with low volatile organic compound content, and there is no need to add organic solvents, so there is no need to conduct VOC testing. With the hard core power of "0VOCs", WANAN construction machinery powder coating puts on a "green" armor for construction machinery. Among the more than 700 proposals related to ecological and environmental protection at the two sessions in 2025, "promoting green manufacturing" is listed as a key topic. The "Made in China 2025" special plan clearly proposes to increase the proportion of green paint to more than 30% by 2028. The Ministry of Ecology and Environment issued the "comprehensive treatment plan for volatile organic compounds in key industries" clearly requires construction machinery manufacturing to vigorously promote the use of powder coatings and other environmentally friendly coatings, which means that the construction machinery industry needs to accelerate the elimination of traditional solvent-based coatings and turn to green materials such as powder coatings. WANAN construction machinery powder coating is an environmentally friendly "4E" coating with 100% solid content (4E: high efficiency, energy saving, environmental protection and economy), which reduces the carbon footprint of traditional paint powder coating by > 60%, and has become the first choice for construction machinery coating to replace solvent-based coatings because of its solvent-free and low-pollution characteristics. In practical application, due to regional climate differences, construction machinery has been exposed to different temperatures and humidity in the outdoor environment for a long time, and the coating of traditional coatings is prone to blistering, chalking, and falling off under extreme temperature and humidity, chemical corrosion, and mechanical wear and tear, which not only shortens the life of the equipment, but may even cause structural safety hazards. WANAN Group has a testing center that has obtained CNAS authoritative certification, and its product testing capabilities have reached the leading level. According to data released by Nielsen, a world-renowned research organization, 64% of consumers say that the appearance of products affects their purchase decisions. Today, excavators, loaders and other equipment are becoming more and more homogeneous, and the coating texture has jumped from "accessory decoration" to the core battlefield of brand premium. WANAN Group can tailor construction machinery powder coatings with rich colors, gloss and texture according to the different needs of customers for coating surfaces. Excellent yellowing resistance, gloss retention and color retention performance can ensure the durability and beauty of construction machinery coating products.The electrostatic spraying process of powder coating can solve the coating needs of corners, holes and welds, solve the problem of coating special-shaped parts, give product design a higher degree of freedom, meet different brand styles and market positioning, and make construction machinery products show a distinctive charm from the appearance, enhance product recognition, further enhance brand image, and improve the market competitiveness of products. In the field of construction machinery manufacturing, the cost control of the coating link is by no means a simple material price game, but a systematic optimization throughout the whole cycle of equipment production, use and maintenance. At the production end, WANAN Construction Machinery powder coating can realize automatic spraying, and the overflow coating can achieve a recycling rate of more than 99%, saving material and labor costs while spraying and molding at one time, reducing the waste of resources and energy consumption caused by multiple processes such as traditional paint primer, middle coat and topcoat. On the operation and maintenance side, the excellent protection performance can minimize the maintenance cost, reduce the downtime loss caused by corrosion, wear and tear of the equipment, ensure that the construction machinery products maintain an efficient and stable operation state, reduce costs and increase efficiency in the whole life cycle, and create significant economic benefits for the enterprise.  

Powder coating features The successful implementation of the powder coating process is a major breakthrough in the coating process of the construction machinery industry, which has been greatly improved in terms of production cost, construction technology, environmental protection and automation in terms of traditional solvent-based coatings to powder coatings.   The powder coating process offers the following advantages: 1) Powder coating does not contain organic solvents, does not emit harmful gases in production, can prevent air pollution, and improves the working conditions of workers, belongs to environmental protection coatings, while the solvent content of traditional paints is more than 40%, and contains a large number of toxic substances such as toluene and xylene;  2) Powder coating can be recycled, the utilization rate is more than 95%, or even up to 99%, and the paint utilization rate is generally 35%~50%; 3) It is easy to get a thicker coating (50~300μm) at one time, so it can reduce the construction process, save energy and improve efficiency; 4) reduced risk of fire due to the absence of solvent volatilization; 5) Powder coating has excellent mechanical and chemical properties; 6) The yield of powder spraying is higher than that of spray painting, generally speaking, the rejection rate of spray painted parts is about 10%, while the powder spraying parts are about 1%, and the repair rate is low, which is conducive to reducing costs; 7) The construction is simple, does not require very skilled operation technology, is easy to master, there will be no sagging problem when the film is thickly coated, and it is easy to implement automatic assembly line coating; 8) Since the powder coating is solid, it is easy to manage in storage.   Cab powder coating process   1. Process flow Upper part→ pre-degreasing→ degreasing → washing → washing→ surface tone → phosphating → washing → washing → pure water washing→ cathode electrophoresis → ultrafiltration one → ultrafiltration two → pure water washing→ draining → drying → strong cold → (grinding) → gluing→ powder spraying → drying→ strong cold → shielding → color painting → shielding→ leveling→ drying→ cooling → the next piece.   2. The requirements of powder coating for the white parts of the cab   Construction machinery products are limited by steel, welding process and mold, resulting in many defects on the surface of finished white parts, such as solder joint defects, mold forming defects, grinding defects, etc. Therefore, most of the company's products need to scrape putty, dry, polish, and then spray topcoat after electrophoretic primer to ensure the best appearance. However, the powder coating needs to be in the baking environment of 180~200 °C for a long time in the film-forming process, so the bottom coating is required to have high temperature baking resistance. In addition, due to the electrostatic adsorption principle used in the coating process of the powder, the base coating is required to be electrically conductive. Therefore, the putty putty and sealant used to make up for the defects of the finished white parts are required to have conductivity and high temperature resistance. In order to solve the problem of white parts defects, a large number of process tests were carried out without changing the previous process, and various brands of putty and sealants were selected at home and abroad for testing, and the test results were: 1) putty is not suitable for large-scale and thick scraping, and the coating is prone to defects such as bulging, pinholes, and orange peel 2) The ratio of putty requires high requirements, otherwise the powder coating is prone to pinholes;   3) The sealant can be used as a process to compensate for weld defects, but a white body needs to be used, otherwise the powder coating is prone to color difference; 4) The sealant cannot be scraped as a compensatory material for the defects of the plate   3. The design of the powder spraying process   3.1 Layout of the powder electrostatic spray gun Most of the construction machinery products are flat or pipe fittings, so they are suitable for high-voltage electrostatic spraying. The characteristics of powder electrostatic spraying technology are that the workpiece can be coated at room temperature, and the utilization rate of powder is high, up to more than 95%; The coating film is thin and uniform, smooth, and has no sagging, and can form a continuous, flat and smooth coating film even on the sharp edges and rough surfaces of the workpiece.   The existence of the inner cavity or some dead angles can be carried out in the back of the manual repair station, and the quality of automatic powder spraying can be checked at the same time, and the uneven parts of the existing powder spit and powder can be dealt with in time to ensure the excellent coating appearance.   3.2 Design of the powder room The design of the powder room mainly focuses on two aspects: first, the size of the opening of the chamber, mainly including the import and export of the workpiece, the telescopic port of the reciprocating machine, and the chain through the mouth, the opening is as small as possible, which can reduce the power of the recovery system, reduce the procurement cost and use cost;Second, the selection of wall plate materials, the wall plate of different materials has different adsorption properties for powder, in order to facilitate the operator to clean the powder room after the end of each shift, the material with poor powder adsorption should be selected.Of course, it is necessary to consider the use conditions at the same time, and it is generally recommended to use stainless steel at the bottom, and PP board or PVC board for the surrounding and ceiling   Generally speaking, construction machinery products are composed of two colors, and the output is balanced, and at the same time can not be rotated for mass production, so 2 powder spraying booths can be designed to produce at the same time, so as to avoid color change operations.   3.3 Design of the recycling system   The recovery system of powder coating equipment is generally divided into two types, namely single-stage filter type recovery device and large cyclone filter type secondary recovery device. The appearance coating color of construction machinery products is generally relatively simple, and most of them are 2 colors. Therefore, the selection of single-stage filter type recovery device is conducive to reducing investment and operating costs, and reducing the amount of powder room cleaning at the end of each shift. The single-stage filter cartridge recovery unit consists of the following components: powder filling device, rotary screen (or vibrating screen), powder supply drum, filter element, fan, ultimate filter element, etc   Because the stable air flow blows smoothly into the inside of the powder booth from the various openings around the powder booth, the oversprayed powder is finally brought into the recovery assembly, which prevents the overflow of the powder and improves the recovery efficiency of the powder. In addition, the powder concentration in the powder booth must be below the explosion limit of the powder. Therefore, the design of the actual air volume of the powder room is as follows.   1) Calculation formula of exhaust air volume of powder room Q1＝3600K· S· V Where: Q1 is the exhaust air volume of the powder room, m3/h; S is the total area of all openings in the powder room, m2; K is the efficiency coefficient of the powder room, taking 1.8~3.6, V is the air flow rate of the powder room, m/s, and the speed of inhaling air at the opening is 0.4~0.7m/s.   2) The formula for calculating the exhaust air volume of the recovery device Q2＝D/n·p where: Q2 is the exhaust air volume of the recovery device, m3/h; D is the total amount of powder discharged, g/min; n is the powder coating efficiency; p is the lower limit concentration of powder explosion, 30g/m3. Therefore, the actual air volume of the powder room Q≥Q1, Q2. The wind speed at the opening of the automatic powder spraying chamber is higher than that of the manual powder spraying chamber, so as to adapt to the spraying of multiple guns and large powder supply, to ensure that the powder does not overflow and the powder concentration is about 50% lower than the explosive concentration, and the speed is not more than 0.3m/s near the spraying workpiece, so as to reduce the damage of the air flow to the spray shape and ensure a high deposition rate.   epilogue For the construction machinery industry, powder coating technology, as a new type of environmental protection technology, is one of the important manifestations of green production technology, and has high promotion value.   Some large domestic construction machinery manufacturers not only use powder coating technology in a wide range of OEMs, but also have required most of the outsourcing partners to promote the use of powder coating technology, and its good economic value has been recognized by everyone.

As powder coating technology continues to evolve, so does its use in the automotive sector. In recent years, powder coatings have been widely used to coat engine hoods and body parts. However, due to its thick coating and poor appearance flatness, powder coating has not been widely used in automotive exterior coating with high appearance requirements. In order to save costs and improve the quality of the coating film, powder coating manufacturers are continuously reducing the particle size of the powder coating to improve the flatness of the powder coating film. However, the reduction of particle size also leads to poor fluidity of powder coatings, which seriously affects the use. Therefore, a new technology is needed to improve the flow characteristics of ultrafine powders, such as the use of nano-sized additives as spacers (fluidization additives), to enable the use of ultrafine powder coatings in existing spraying equipment. In addition, more and more heat-sensitive plastic or composite parts are used in the automotive industry, and the development of low-temperature curing powder coatings, especially low-temperature curing ultra-fine powder coatings, has also received wider attention. Accordingly, this paper first reviews the development and challenges of ultrafine powder coatings in the field of automotive coating, and examines the flow properties and coating properties of ultrafine powder coatings after adding fluidizing additives. Application of ultra-fine powder coating in the field of automotive coating 1.1 Ultrafine powder coatings Ultrafine powder coating usually refers to powder coating with a medium particle size of less than 25 μm with a particle size of less than 50. Compared with ordinary powder coatings (medium particle size D50 greater than 30μm) and fine powder coatings (medium particle size D50 between 25~30μm), ultra-fine powder coatings have unique excellent properties. As the particle size decreases, the thickness of the coating film also decreases, so that the coating film has better leveling and good decorative effect. In addition, the economic costs are reduced due to the reduction in material consumption. According to the Geldart powder classification, ordinary powder coatings belong to Class A particles and are easily fluidized; However, when the particle size is reduced to ultra-fine powder coating (Class C particles), the force between the particles (van der Waals force) increases, and the powder particles are prone to agglomeration and cannot fluidize normally, resulting in a series of problems such as air flow transportation and spraying difficulties. In order to improve the fluidity of ultrafine powder coatings, an appropriate amount of fluidizing additives (guest particles) must be added to the coating, and these nano-sized particles adhere to the surface of ultrafine powder particles (host particles) in the form of small agglomerates, increasing the distance between the particles. Because the bulk density or apparent particle density and size of these added guest particles are lower than those of ultrafine powder particles, the interparticle force between the adhered guest particles and the host particles is significantly smaller than that between the host particles, thus reducing the van der Waals force between the ultrafine powder particles. In order to promote the depolymerization of the main particles, the fluidizing additives particles usually need to be evenly dispersed in the ultrafine powder and evenly attached to the surface of the ultrafine powder particles, but they do not need to be attached in the form of single particles, and the form of small agglomeration is more helpful to reduce the inter-particle force of the main particles. Additives can significantly improve the flow of ultra-fine powder coatings, but they can also cause other problems, such as loss of gloss on the surface of the coating film and defects such as craters and "particles". In addition, nano-sized additives are inherently prone to cohesion and tend to form strong and large agglomerates that cannot be dispersed by ordinary dry blending processes (even with high-shear mixers), resulting in unavoidable defects such as "particles" in the final coating. Overcoming these problems requires new technologies, including specially designed additive formulations and special mixing processes, to improve the dispersion and compatibility of additives with powder coatings, ensuring that excellent coating properties are maintained while reducing inter-particle forces and improving flowability. The Particle Technology Research Center of the University of Western Ontario, Canada, has successfully developed a high-efficiency ultra-fine (HEUF) powder coating technology; According to the various resin systems of the coating, the technology adopts the corresponding fluidization additive formulation and optimized addition and dispersion methods to ensure the excellent fluidity, sprayability and coating quality of the ultra-fine powder coating, and its minimum coating film thickness is only 20~30μm (as shown in Table 1). Figure 1 shows the coating surface profile (measured by Dektak contact surface profiler) with an average particle size of 16.4 μm ultra-fine powder coating and 38.8 μm ordinary powder coating. The greater the fluctuation of the ordinate value, the rougher the coating surface. As can be seen from Table 1 and Figure 1, compared with ordinary powder coatings, the high-efficiency ultra-fine HEUF powder coating significantly reduces the surface roughness of the coating film and improves the visual effect of the coating film. The reduction in film thickness results in a significant reduction in cost, while the film also offers the same durability, recyclability, and powder loading rate as standard powder coatings. 1.2 Overview of the application of ultrafine powder coatings in the automotive field With the rapid growth of demand for high-end vehicles in the Asia-Pacific region, as well as the increasing environmental requirements of regulatory agencies such as the Ministry of Environmental Protection of China, the European REACH (Registration, Evaluation, Authorization and Restriction of Chemicals), and the U.S. EPA (Environmental Protection Agency), the automotive coating market is increasingly shifting from solvent-based coatings to low-VOC coatings. As an environmentally friendly product with zero VOC emissions, powder coating has been widely used in wheels, car covers, decorative trims, bumpers, hubcaps, door handles, truck bases, radiators, filters and a large number of engine parts. But powder coatings have their own problems. Ordinary powder coatings typically have higher film thicknesses, lower flatness, and a relatively poor visual appearance, which limit their application in automotive exterior coatings. In order to achieve better coating results, powder coating manufacturers have begun to reduce the film thickness and improve the flatness of the coating film by reducing the particle size of the powder coating. In recent years, fine powder coatings have begun to be applied to car body coatings. General Motors and Chrysler have achieved mass production of midcoats in the United States and several other countries. The German company BMW has successfully applied fine powder varnish (topcoat). Although fine powder coatings have made great progress in the field of automotive coating, so far, ultra-fine powder coatings with a particle size of less than 25 μm have not been applied to the field of automotive coating. Although fine powder coatings have made great progress in the field of automotive coating, so far, ultra-fine powder coatings with a particle size of less than 25 μm have not been applied to the field of automotive coating. Powder coatings have not yet made a major technological breakthrough in the application of this high-end market, so their application in automotive body coating is still limited, and more than 95% of body coatings are still liquid coatings. The flow problem of ultrafine powder coatings is an important factor limiting their application in the field of automotive coatings. The development of new fluidization additive technology will be the main way to solve this problem, and will also open a new door for the application of ultrafine powder coatings in the field of automotive coatings.

The cycle of the four seasons, the 24 solar terms, the 72 phenological changes, and the different solar terms correspond to the unique climate changes, weaving a colorful picture scroll for the world, each with its own characteristics and complementing each other. In spring, the peach and willow are green, the sky is blue and lotus in summer, the maple is red and chrysanthemum yellow in autumn, and the winter solstice is snow-white and plum and zhu, and the five colors are all poems. In the world of WANAN's color aesthetics, the beauty of color is deeply rooted in the natural timing of the shift. The sting began, the spring thunder moved, and everything woke up. The stunning solar term symbolizes the arrival of the mid-spring season, and the rise and fall of colors are also in the ever-changing, each color embodies the awe and love of WANAN powder coating for the natural timing.   The stinging solar terms, the rolling spring thunder awakens the sleeping earth, and the red and fertile soil heralds the hope of a bumper harvest, and agricultural activities have also entered a busy stage. WANAN red series powder coating captures the natural earth color, contains the simple and vigorous vitality of the soil, fully interprets the beauty of the power of construction machinery with color, and fully demonstrates the solidity and stability of construction machinery.     A thunderstorm began, and the light rain was new. The spring rain moistens all things that sprout, and the red young stems when the new shoots break the ground, implying new beginnings and hope. The WANAN red series of powder coatings breaks the silence with warm vitality and gives the architectural space a strong visual impact. It is widely used in the field of building materials such as doors and windows, guardrails, etc., injecting a warm texture into the cold and hard metal materials, and conveying the hope of spring.     It is a kind of dyed grass recorded in ancient books, and it can also be extended to a red flag, which is bright and warm, full of vitality and vitality. In the season of revival, nature announces the arrival of new life in its own way. This season of hope is like a red flag waving in the wind, leading people towards a better future. The WANAN red series of powder coatings perfectly presents the warmth and vitality of the silk on the casual furniture, bringing a dazzling color to our living space, and making every corner of life full of spring warmth and vitality.     In the season of sting, the earth rejuvenates. The color of Shunsheng, which originates from the peony that blooms in spring, has both the warmth and vitality of red, and the mystery and nobility of purple, full of vitality and hope. WANAN Red series powder coatings break the cold, hard and monotonous visual inertia in traditional industrial scenes with vigorous vitality. The calmness and elegance of the fuchsia color relieves the tension of high-intensity work. WANAN powder coating uses color to awaken the subconscious closeness to natural life, and dissolves the oppressive feeling of the industrial environment between rigidity and softness.     WANAN The beauty of the stunning color starts from the "Chiti", inherits the "vermilion grass", and turns to the "silk sting", which is in line with the "obedience". Every touch of color tells the story of spring, showing the vitality and hope of life. With the flow of solar terms, the rise and fall of colors are ever-changing, and a scene is beautiful. WANAN powder coating paints the beauty of the solar term with color, and with the aesthetic concept of "color without boundaries", every moment of life glows with a unique and charming brilliance.

As an environmentally friendly coating material developed in recent decades, powder coating has the advantages of high coating efficiency, good protection and decoration, so as to achieve sustained and rapid development. With the rapid increase in powder coating manufacturers and powder coating production, the application field of powder coating continues to expand, the competition between powder coating manufacturers is becoming more and more fierce, and powder coating users have higher and higher requirements for the quality of coating products, so more stringent requirements are put forward for the product quality control of powder coatings. The author talks about the quality control of powder coatings, combined with the actual situation of the company's production of powder coatings for many years, for the reference of peers.   1.The production principle of powder coating   The production of powder coating is to add solid materials such as resin, curing agent, pigment, filler and additives to the mixer according to the formula amount without using solvents or water and other media, and then input the extruder into the extruder for melting and mixing after full mixing and dispersion; Then press into thin sheets on the tablet cooler, cool and crush into thin sheets, and then crush by air classification grinding and then cyclone separation, the separated coarse powder is screened by the vibrating screen to obtain the finished product, and the fine powder is recovered through the bag filter, the whole production process is a physical process, basically there is no chemical reaction.   2. Factors influencing product quality   2.1 Stability of the formulation The quality of raw materials is the basic condition to ensure the quality of powder coating products, so the technical indicators of raw materials, such as resin gelling time, softening point, and reactive functional group technical indicators, must be regularly spot-checked to ensure product quality and customer needs. The principle of powder coating formula design is not only to ensure product quality to adapt to the cruel market competition, but also to comprehensively consider the cost of each raw material in the formula, but do not use shoddy, or even replace outdoor product formula with indoor powder coating formula, deceive users, and cause adverse effects; At the same time, it is also necessary to make the formula stable and continuous, and control the quality of the same batch or different batches of powder coating products.   2.2 Production process control The production process of powder coating is a physical mixing process, and the purpose of pre-mixing is to mix powdered materials such as resins, pigments, fillers, additives and so on in a dry state. Create conditions for melt extrusion and obtain better dispersion effect. If you mix it at will, or even manually stir and mix, it will cause the instability of the formula and the quality of the powder will decrease; Extrusion is the core process of powder production, which has a decisive impact on the quality of powder, the mixing effect of the extruder is not good, which will affect the gloss of the product, and the leveling will also become poor, and there will be uneven color mixing, local gelatinization, the formation of plate particles and other drawbacks; The main purpose of grinding is to make the particle size distribution of the powder suitable for electrostatic spraying.   2.3 Particle size of powder coatings Powder coating suitable for electrostatic spraying, its particle size is better between 10~90μm. The particle size of powder coating is an important indicator of the quality of powder coating, and the leveling, powder rate and stability of powder coating products are related to powder particle size, therefore, controlling powder particle size is the key issue of powder coating quality. The particle size control of powder coating suitable for electrostatic spraying is 20~90 μm, and the customer is satisfied with the powder quality after use.   2.4 Powder coating fluidization effect The powder with good fluidity is easy to fluidize during use, it appears very fluffy, and has a water-like effect, from the powder supply barrel to the spray gun, the powder is transported lightly, and the powder comes out of the nozzle and atomizes well, and there is no agglomeration or spitting powder. The fluidity test of powder coating is guided by the Selier fluidity test method, that is, a certain amount of powder sample (about 250g) is weighed and placed in a cylindrical plastic container with a porous bottom plate with a diameter of 100mm; Compressed air is introduced from the bottom of the multi-well plate at a rate of 200 L/h to fluidize the powder, and the mass of the powder flowing out within 30 s is determined, and the fluidity of the powder can be calculated according to the following formula: Where: the mass of the outgoing powder in m —30 s, g; H0 — the height of the powder in the container when it is not aired, mm; H1 — The height of the powder in the container when the fluidization is stable, mm.   2.5 Mechanical properties and others Powder coating manufacturers usually test the following indicators: gloss, film thickness, color difference, impact, cupping, pencil hardness, adhesion, flexibility, etc., in order to test the quality of powder coating products and ensure that the products meet the needs of customers.   3. Conclusion There are many influencing factors for the quality of powder coating, and sometimes a variety of factors are intertwined, resulting in problems in the quality of spraying products, so to improve the quality of powder coating products, it is necessary to continuously explore and summarize in production practice, pay attention to all aspects of the production process, establish a sound product quality management system, and improve product quality. At the same time, good powder coating products must also cooperate with good spraying process conditions to produce ideal spraying products.

At the beginning of 2025, DeepSeek will explode out of the circle, and this "mysterious oriental power" has aroused widespread attention and discussion around the world. Whatever "soul torture" is asked, it always responds quickly. Let's talk to the "strongest brain" in the AI industry and see what an excellent high-temperature powder coating looks like in the eyes of artificial intelligence.   WANAN Group has been deeply engaged in the field of powder coatings for nearly 30 years, attaches great importance to technological innovation, and develops and produces high-temperature resistant powder coatings, constantly refreshing new heights of temperature resistance.   After the surface of the coated product is pretreated with iron phosphating and sandblasting, the cured coating can stably withstand the temperature resistance of 200 to 400 °C and above.   In the extremely high-temperature environment, the coating of WANAN's high-temperature powder coating can always maintain its original luster, and there will be no problems such as loss of light and discoloration, blistering, and coating chalking and peeling. Whether it is in a harsh industrial production line or in a complex and changeable outdoor environment, WANAN's high-temperature powder coating always provides all-round effective protection for the substrate with excellent temperature resistance and extends the service life of the product.   In the field of coatings, which pursue extreme performance and long-lasting durability, WANAN's high-temperature powder coatings interpret a new level of quality and performance with outstanding performance. Through repeated experimental tests, it has been proved that the coating of WANAN high-temperature resistant powder coating can maintain stability under the harsh conditions of hundreds of degrees Celsius and meet the level 0 adhesion (IOS standard evaluation is divided into 0-5 grades, of which grade 0 is the best and grade 5 is the worst; Equivalent to International Standard 5B, i.e. the incision edge is completely smooth and there is no peeling of the lattice edge after the scratch method).     WANAN's high-temperature powder coatings are invisible shields that can easily cope with red-hot ovens, pipes, and the interior of harsh hot blast stoves, protecting substrates from high-temperature erosion with excellent adhesion, extending equipment life and saving valuable maintenance costs.   In the harsh neutral salt spray test environment, WANAN's high-temperature powder coating (taking 300°C series products as an example) can easily pass 1000 hours of continuous testing, and the unilateral corrosion width is controlled within 2mm, ensuring that the coated products can effectively resist the erosion of salt, water, acid, alkali and other substances in practical applications.   As a typical environment-friendly coating, WANAN high-temperature resistant powder coating has a carbon footprint of > 60% compared with traditional coatings, is 100% solid content, 0VOCs pollution, non-toxic, solvent-free or other harmful substances, and the spray powder can be recycled and the utilization rate is more than 99% "4E" type (i.e., environmental protection, energy saving, economical and efficient) coating, which is also an environmentally friendly coating product with sustainable development and green and low-carbon requirements supported by national policies.     WANAN has a high degree of automation in high-temperature powder coating, which effectively reduces energy consumption and resource waste, and makes a positive contribution to the green development of high-temperature resistant coating products.   WANNAN Group deeply researches the surface coating process, and can provide customized appearance services according to customer needs, and the ever-changing texture and luster collide with the vast sea of color inspiration, so as to better meet the needs and aesthetic preferences of different user groups, and bring infinite possibilities to life.     Excellent leveling brings excellent hiding power, meets the needs of complex construction and coating such as flat and curved surfaces, realizes product modeling creativity with higher design freedom, and brings more possibilities to the visual image of products. WANAN  

In recent years, with the continuous strengthening and deepening of China's environmental protection policy, higher standards of environmental protection requirements have been put forward for the paint industry, and the domestic paint industry has been transformed and upgraded in the direction of water-based, high solids, and solvent-free, and powder coatings have developed rapidly. Compared with traditional industrial solvent coatings, powder coatings are more economical and environmentally friendly, and have excellent chemical resistance, corrosion resistance and high mechanical strength. In the process of processing and curing, powder coating is subjected to mixed thermal processing and high-temperature baking, and if the protection of the molecular chain is insufficient in the production process, it is easy to undergo thermal and oxidative aging and decomposition of the molecular structure, which will affect the performance and color of the coating. And more powder coatings are increasingly being applied to high-temperature environments, such as rice cookers, microwave ovens and other small household appliances coatings, these factors put forward higher requirements for the high-temperature stability of powder coatings. As a common anti-aging additive, antioxidants provide excellent anti-thermal and oxidative aging protection and long-term stability for polymer materials, and are an indispensable component of powder coating solution system, and more and more application requirements are expected to improve the high-temperature stability of powder coatings through the optimization of antioxidant systems. At present, the traditional antioxidants used in powder coatings mainly include hindered phenolic antioxidants 1010 and 1076, phosphite antioxidants 168 and 626, etc., which basically cannot meet the thermal stability of powder coatings under high temperature conditions. In this paper, a composite antioxidant system for powder coatings is developed, which can effectively prevent the degradation of powder coatings by thermal and oxidative aging at high temperatures, and provide excellent protection for coating colors, which can expand the development and application of powder coatings in the field of high-temperature home appliances. Experimental part 2.1 Preparation of specimens Polyester resin, curing agent, antioxidant, barium sulfate, titanium dioxide and other additives are batched in a certain proportion, premixed, the mixture is melted and extruded, broken after tableting, and the powder coating product with a certain particle size is obtained after sifting the crushed powder. 2.2 Test equipment High temperature oven (binder), twin screw extruder (Deteng), colorimeter (X-Rite).   2.3 Test methods   2.3.1 Antioxidant thermal stability test The antioxidants used in the four formulations of ABCD were placed in a 230°C oven for 0.5h to test their color difference and weight loss rate. 2.3.2 Powder coating thermal stability test The powder coating sample in 2.1 was electrostatically sprayed and cured at 200°C for 10min to obtain powder coating. In order to evaluate the effect of antioxidants on the heat resistance of powder coatings, the powder coating was put into a high-temperature aging oven with a heat aging condition of 230°C for 2h. Test the gloss retention and color difference of the coating. Results and Discussion 3.1 Mechanism of action of antioxidants The reticulated polymer coated in the paint is made up of countless molecular segments linked together by chemical bonds, which contain hydrogen, oxygen, double bonds, etc.; They are susceptible to heat and oxygen attack, producing large amounts of free radicals and hydroperoxides, which can damage the polymer segments and eventually cause the coating to begin to age, with gloss loss, surface chalking, and discoloration. The addition of antioxidants to powder coatings can effectively inhibit the thermal-oxidative aging behavior of polymers. Antioxidants are divided into two main categories: primary antioxidants and secondary antioxidants. The main antioxidants mainly include aromatic amine antioxidants and hindered phenolic antioxidants, and their mechanism of action is to capture the free radicals R▪ and ROO▪ formed in the chain reaction stage and terminate the chain reaction. Auxiliary antioxidants mainly include phosphite antioxidants and thioester antioxidants, and their mechanism of action is to decompose ROOH to produce stable substances. The combination of main and auxiliary antioxidants can play a certain synergistic role to achieve a better antioxidant effect. 3.2 Study on the thermal stability of antioxidants The thermal stability of the antioxidant itself determines whether it can provide good protection for the resin during high-temperature processing and use. If the antioxidant itself has poor thermal stability and decomposes at high temperatures, it loses the properties of the antioxidant and cannot provide good protection for the resin from thermal and oxidative aging. As can be seen from Table 2, the color change and weight loss rate of the four antioxidants under high temperature aging are not serious, indicating that the thermal stability of the four antioxidants is good. Among them, formula A is a single hindered phenolic antioxidant. Formula B is a single phosphite antioxidant with a high weight loss rate, indicating that B has undergone a certain degree of decomposition. Formula C is a commonly used compound antioxidant system on the market. Formula D is a special composite antioxidant system developed for powder coatings, and the experimental results show that the color change and heat loss rate of formula D are excellent at high temperature. 3.3 Effect of different antioxidants on the heat resistance of powder coatings It can be seen from the data in Table 3 that after 2 hours of high temperature aging at 230 °C, the powder coating was damaged to varying degrees, and formula A and B were both single antioxidant systems, and the protection effect of powder coating was slightly poor, and the protection of formula C against thermal and oxidative aging of the coating was significantly better than that of A and B. Among them, the D formulation, as an antioxidant formulation specially developed for powder coatings, has the best performance for the pulverization and color protection of the coating, so that the high temperature resistance of the powder coating has been significantly improved. epilogue The results show that: 1. There are differences in the thermal stability of different antioxidants at high temperature, among which the thermal stability of formula B (phosphite antioxidants) is poor, and formulations A, C and D all have excellent thermal stability. 2. It is found that the protection of the composite antioxidant system against the thermal and oxidative aging of powder coatings is better than that of the single-component hindered phenols or phosphite antioxidants, and the D formula of the composite antioxidant system developed for powder coatings has better protection against the thermal and oxidative aging of the coating under high temperature conditions.