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In the ever-evolving world of coatings, powder coatings have emerged as a revolutionary and sustainable alternative. This article delves into the latest happenings in the powder coatings industry, exploring new technologies, market trends, and the impact on various sectors.​ Technological Advancements Driving the Industry Forward​ One of the most significant trends in the powder coatings realm is the continuous development of innovative technologies. Manufacturers are constantly striving to improve the performance and quality of powder coatings, making them more durable, efficient, and environmentally friendly.​ Low-Temperature Curing Technologies​ A notable advancement is the rise of low-temperature curing powder coatings. Traditional powder coatings often require high temperatures for curing, which can be a limitation, especially when coating heat-sensitive substrates like certain plastics or wood composites. However, recent research and development efforts have led to the creation of powder coatings that can cure at significantly lower temperatures, typically in the range of 120°C to 150°C. This not only expands the range of materials that can be coated but also reduces energy consumption during the curing process, aligning with the global push for sustainability. For example, companies like AkzoNobel have introduced low-cure powder coating innovations that cure at temperatures as low as 150°C while maintaining high-performance standards. This is a major leap forward in both sustainability and process efficiency, and the trend towards even lower curing temperatures is expected to continue.​ Antimicrobial and Special Functionality Coatings​ In response to the growing demand for enhanced hygiene and specialized coatings, there has been a surge in the development of antimicrobial powder coatings. These coatings are designed to inhibit the growth of bacteria, fungi, and other microorganisms on coated surfaces. They find applications in various sectors, such as healthcare facilities, food processing plants, and public spaces, where maintaining a clean and germ-free environment is crucial. Italian company Stardust Powder Coatings, for instance, started the development and testing of antiviral powder coatings in March. These coatings can reduce the risk of virus transmission on metal surfaces, such as furniture and lighting fixtures, by inhibiting the viruses present on them. Additionally, powder coatings with other special functionalities, such as self-cleaning properties, electrical insulation, and high chemical resistance, are also being developed to meet the diverse needs of different industries.​ Advance​d Pigment and Additive Technologies The use of advanced pigments and additives is another area of progress in powder coatings. Pigments not only provide color and opacity but also play a role in UV protection and durability. New pigment technologies are enabling powder coatings to achieve a wider range of aesthetics, including metallic and pearlescent effects. Additives, such as flow modifiers, degassing agents, and UV stabilizers, are being refined to improve the overall performance of powder coatings. Flow modifiers help in achieving smoother finishes, degassing agents prevent bubble formation during the curing process, and UV stabilizers enhance the outdoor performance of coatings, making them more resistant to fading and degradation caused by sunlight.​ Market Trends and Growth Prospects​ The powder coatings market has been experiencing steady growth in recent years, driven by factors such as environmental regulations, increasing demand for sustainable products, and the expanding applications of powder coatings across multiple industries.​ Global Market Expansion​ According to MarketsandMarkets, the market size for powder coatings is projected to grow from ​ 11.6billionin2020to   14.9 billion by 2025, at a compound annual growth rate (CAGR) of 5.2 percent. The Asia-Pacific (APAC) region, particularly China, India, and Southeast Asian countries, is witnessing strong growth in the powder coatings market. In 2023, the global powder coatings market reached a total volume of around €12.4 billion, constituting 15 - 20% of the global industrial coatings market. Asia leads the way in terms of growth, reflecting rapid industrial growth and a shift towards sustainable production methods. North America and Europe are also significant markets, driven by strict environmental standards and high-performance demands.​ Growing Demand from Key Industries​ Powder coatings are finding widespread use in various industries. In the automotive sector, they are used for coating wheels, trims, chassis, and other components, providing high durability and corrosion resistance. With the increasing production of electric vehicles (EVs), the demand for powder coatings in this segment is expected to grow further, as EV manufacturers seek coatings that can withstand the unique requirements of electric vehicle components. The appliances industry is another major consumer of powder coatings, applying them to refrigerators, washing machines, ovens, and other household appliances to provide a tough, protective, and aesthetically appealing finish. In the architectural and construction industry, powder coatings are used for both indoor and outdoor aluminum and steel structures, such as window frames, doors, fences, and facades. They offer excellent weather resistance and color retention, making them a popular choice for building exteriors. The furniture industry also benefits from powder coatings, as they enhance the lifespan, color retention, and scratch resistance of metal office furniture, shelving, and outdoor furniture. Additionally, in the electronics industry, powder coatings are used to protect electrical components due to their excellent thermal and electrical insulation properties.​ Sustainability as a Key Driver​ Sustainability is a major factor fueling the growth of the powder coatings market. Powder coatings are environmentally friendly as they do not require a liquid carrier, resulting in no release of harmful volatile organic compounds (VOCs). This makes them compliant with strict environmental regulations in many regions. Moreover, powder coatings are highly recyclable, with up to 95% of overspray powder being able to be recycled and reused. The electrostatic spraying process, which is commonly used for applying powder coatings, decreases the overspray rate, leading to a utilization rate of more than 90%, a clear advantage over traditional liquid paint systems. The ability of powder coatings to provide extreme hardness and good adherence in just one layer, without the need for a primer in many cases, while also offering superior corrosion resistance, makes them an economical and sustainable choice for many applications.​ Challenges and Solutions in the Powder Coatings Industry​ Despite the numerous advantages and growth prospects, the powder coatings industry also faces certain challenges.​ Regulatory Pressures​ The industry is subject to various regulatory requirements, both in terms of environmental regulations regarding emissions and safety regulations related to the composition of coatings. For example, the recent EU ruling classifying titanium dioxide as a category 2 - suspected carcinogen by inhalation has had a significant impact on the powder coatings industry. This directive requires the labelling of mixtures (including coatings) that possess more than 1% content of TiO₂. Since this colorant pigment is estimated to be present in over 60% of all powder coatings produced worldwide, and there is currently no replacement that can match its opacity, performance, and cost-effectiveness, coating producers have been forced to revamp their labels and Safety Data Sheets. To address such regulatory challenges, the industry needs to invest in research and development to find alternative materials and formulations that meet the regulatory standards without sacrificing performance.​ Competition from Traditional and Alternative Coatings​ Powder coatings face competition from traditional liquid coatings, which still hold a significant share in the market, especially in some applications where they have established usage patterns. Additionally, new alternative coatings, such as water-based coatings, are also emerging as competitors. To stay competitive, powder coatings manufacturers need to continuously demonstrate the unique advantages of powder coatings, such as their superior durability, environmental friendliness, and cost-effectiveness over the long term. They must also focus on innovation to develop coatings that can outperform traditional and alternative coatings in specific applications.​ Cost Pressures​ The cost of raw materials, energy, and production can pose challenges to the powder coatings industry. Fluctuations in the prices of resins, curing agents, pigments, and other raw materials can impact the profitability of manufacturers. Rising energy costs also affect the curing process, which is energy-intensive. To mitigate these cost pressures, companies are exploring ways to optimize their production processes, improve resource efficiency, and source raw materials more cost-effectively. Recycling overspray powder and implementing energy-saving measures in the curing process are some of the strategies being adopted.​ The Road Ahead for Powder Coatings​ Looking to the future, the powder coatings industry is expected to continue its growth trajectory, driven by technological advancements, increasing demand for sustainable coatings, and expanding applications in various industries. The development of new and improved powder coating technologies, such as further advancements in low-temperature curing, antimicrobial coatings, and specialized functionality coatings, will open up new markets and opportunities. As environmental regulations become even more stringent globally, powder coatings' eco-friendly characteristics will make them an even more attractive option. The industry will also need to collaborate closely with raw material suppliers, equipment manufacturers, and end-users to address challenges and ensure the continued success of powder coatings in the coatings market. With the right strategies and a focus on innovation, powder coatings are set to play an increasingly important role in the coatings landscape in the years to come.​  

introduction Powder coating is a solid coating in powder form. This is a type of paint that is usually dispersed with air as a carrier and applied to the surface of the wheel hub. Electrostatic spraying is usually adopted, which has attracted great attention from the entire coating industry with its high production efficiency, excellent coating performance and appearance effect, good ecological environmental protection and outstanding economy in the world. With an annual growth rate of more than 12%, it is one of the most promising paint varieties. In the film-forming process of powder coating, many phenomena are related to surface tension. For example: pinholes on the surface, orange peel, peeling of coatings, mismatch between paints and coatings, etc. To this end, the following focuses on analyzing and solving the problem from the surface tension of the powder. 1. The manufacturing process of powder coatings The determination of powder coating formula is generally determined according to the technical requirements of the customer's product and its own production environment, and the formula design should fully consider the customer's requirements and the rationality of its own production.   2. Coating of powder coating The coating production line is completed according to the technical requirements of the coated workpiece and the generation batch.   3. Powder coating film-forming process After the powder coating is applied to the surface of the wheel, there are generally four processes in the film formation process:   3.1 Softening process After the powder absorbs a certain amount of heat, the resin in the powder will become sticky and soften due to heat absorption.   3.2 Melting process When the resin in the powder absorbs a certain amount of heat, the active chemical bonds in the resin open. The powder will then exist on the surface of the product in a molten state. This phase is extremely short.   3.3 Leveling process When the powder exists on the surface of the product in a molten state, it flows from a continuous uneven surface to a relatively smooth and flat surface, which is the leveling process.   3.4 Curing process After melting, the active chemical bonds of the powder coating increase sharply in molecular weight and viscosity through cross-linking reaction, and finally solidify into a hard coating film, which is the curing process.   4. Brief description of surface tension Any force acting on the surface of a liquid, reducing the surface area of the liquid. This is called liquid surface tension. It occurs due to the presence of a thin layer on the surface where the liquid comes into contact with the gas, called the surface layer. The molecules in the surface layer are sparser than those inside the liquid, and the distance between the molecules is larger than that inside the liquid, and the interaction between the molecules is manifested as gravitational force, and the surface energy of the powder coating particles when they are melted is similar to that of the general liquid. Therefore, the powder coating film formation process can be analyzed.   5. Several surface tension problems related to powder coating   5.1 Orange peel Orange peel is a local vortex effect of liquid flow during the film-forming process of powder coatings. This is due to the change in surface tension due to the change in viscosity during melting of the powder coating. In this way, a high viscosity and low surface tension coating sinks to the middle of the vortex (i.e., the later depression), and a low viscosity and high surface tension coating rises to the periphery of the vortex (i.e., the later convex part), and the following measures can be taken to reduce the effect of orange peel:   5.1.1 Regular spraying and baking A coating that is too thick at one time or bakes that heats up too quickly can cause the orange peel to be noticeable. The primary coating should be 60-80um, and the melting leveling time should be appropriately extended, which is conducive to the leveling of powder coating.   5.1.2 Increase the viscosity of powder coatings From the above reasons for the formation of orange peel, it can be seen that increasing the viscosity of powder coating during melting can increase the flow resistance during melting and reduce orange peel.   5.1.3 Appropriate selection of leveling agent Generally, the leveling agent used for powder coating should have two effects, namely wetting effect and leveling effect. The wetting effect is to increase the leveling of the system when the powder is around 1O0°C. At this time, the surface tension should be as small as possible, i.e. the leveling effect greater than 150°C is the main one. The surface tension of the powder should be a little larger to increase the leveling properties, so usually the leveling agent generally contains more than two materials.   5.2 Shrinkage porosity Shrinkage pore refers to a special defect on the surface caused by a point of low surface tension during the formation of a powder coating. If observed with an electron microscope. Shrinkage porosity is mostly formed by a small number of insufficiently wetted particles and the surrounding incompatible resin, that is, in a large sag vortex, there is a protruding small dot coating film flowing from the low surface tension point to the high surface tension point to form the shrinkage porosity. In general, the low surface tension point can be dust, oil droplets, etc. during processing, or it can be powder that has not been sufficiently wetted. In order to reduce the impact of cratering, the following measures can be taken:   5.2.1 Cleanliness of the entire processing environment In order to avoid the occurrence of shrinkage porosity due to external environmental reasons, special attention should be paid to the cleanliness of the entire working environment.   5.2.2 Properly select some wetting agents Some wetting agents can effectively wet and disperse particles that cause cratering.   5.3 Pinholes Pinhole refers to the process of powder coating from melting to curing, and the gas in the powder coating passes through the high-viscosity, nearly closed elastic resin layer from the bottom layer to the coating surface. The defects formed by the non-escape are generally caused by the low molecular substances brought in the raw materials, the volatiles adsorbed on the surface of the coated workpiece, the defects caused by the powder coating process, or the defects generated during the curing process of some types of powder coatings. These bubbles form a certain number of bubble groups in the molten state of the coating film. In order to reduce the effect of pinholes. The following measures can be taken: strictly control the quality of the surface treatment of the wheel hub and the spraying process. The surface treatment of the wheel hub is required to contain stains, spots and other small molecule substances attached to the surface of the hub. If it is a large workpiece such as cast iron, it is recommended to preheat it first, and the air compressor should release water frequently. When electrostatic spraying, it is necessary to control a certain thickness of the coating film, and it is recommended not to exceed 100um.   6. Conclusion We firmly believe that the development of thermosetting powder coating is bound to be the trend of the times, with the continuous innovation of products (such as low-temperature curing, super weather resistance, etc.), for the application of powder coating to expand a broader field, and constantly promote the development of the entire powder coating industry.  

Definition and technical characteristics of powder coatings Powder coating is a coating that exists in a powder state and has solid properties, which is different from traditional liquid coatings. Its main components include resins, pigments, hardeners and additives. The application process of powder coating usually consists of two steps: electrostatic spraying and high-temperature curing. In the electrostatic spraying process, the powder coating is sprayed onto the grounded metal surface by an electrostatic spray gun to form a uniform coating. Subsequently, the coating cures at high temperatures to form a strong protective film.   The main technical features of powder coating include: Environmental protection and pollution-free: powder coating does not contain volatile organic compounds (VOCs), will not release harmful gases during construction, and is a green building material. Efficient utilization and recycling: The utilization rate of powder coating is high, and the oversprayed powder can be recycled and reused, and the utilization rate can reach more than 99%. Excellent physical properties: The coating has good adhesion, compactness, strength and toughness, and can effectively resist impact and corrosion. Multiple Finish Options: Powder coatings are available in a variety of colors, textures, and gloss levels for creative and custom designs.   Application areas of powder coatings Powder coatings are widely used in many fields due to their excellent performance and environmental protection characteristics: Building materials field: used for surface treatment of aluminum profiles, metal railings, building signs, etc. Home appliance field: suitable for the coating of refrigerators, washing machines, microwave ovens and other home appliance shells. Automotive: Used for painting automotive parts, wheels, wheels, etc. Furniture field: used for indoor and outdoor furniture painting, improve the aesthetics and durability of furniture. Industrial equipment: used for the coating of mechanical parts, pipes, steel structures, etc. Medical equipment: used for painting medical beds, trolleys, trays, etc.   Environmental performance of powder coatings Powder coating is an environmentally friendly and non-toxic building materials coating, which will not volatilize harmful substances during construction, and its material recycling rate is as high as 99%. In addition, powder coatings do not involve volatile organic compounds (VOCs) during production and use, and do not negatively affect air quality. This kind of coating will not produce waste water, waste gas and other "three wastes" problems in the curing process, which greatly reduces the risk of environmental pollution.   The future of powder coatings With the enhancement of environmental awareness and the advancement of technology, the application range of powder coatings continues to expand. For example, the development of low-temperature curing powder coatings allows them to cure at lower temperatures, saving energy and reducing CO2 emissions. In addition, the use of renewable and recycled raw materials, such as recycled PET bottles, further reduces the environmental impact.   conclusion Powder coatings have become an important choice for modern painting due to their environmentally friendly, efficient, durable and versatile characteristics. It not only meets the aesthetic requirements of the product surface, but also provides excellent protection performance, while meeting environmental protection requirements and reducing the impact on the environment. With the continuous advancement of technology, the application range of powder coatings will be further expanded, providing environmentally friendly and efficient coating solutions for more industries.  

  WANAN metal powder coatings The sun burns for 4.6 billion years, and the aurora dances for thousands of years...... Light does not need to be created, but only desires a "stage", to be transmitted, frozen, and seen. Wan'an metal powder coating makes the light stop, and the substrate dances with the light. We don't create light, we transmit light. In the microcosm of WANAN metal powder coatings, ultra-fine metal pigments such as aluminum powder and pearlescent powder with a content of up to 20% build a panoramic stage of light. When the beam of light pours from any angle, each ultra-fine metal particle can refract the dazzling light finely, forming a 360° high-flash effect without blind spots, presenting a glossy finish comparable to liquid paint with soft and delicate light and dark changes. On the wheels of the car, light and shadow rotate with the wheels to outline a dynamic arc; On the curtain wall of the building, the sunlight swayed into tiny stars...... WANAN metal powder coating makes every collision between light and substrate a visual feast of Ambilight. WANAN Group has been deeply involved in the field of powder coating for nearly 30 years, and attaches great importance to the safety, reliability and quality stability of powder coating products while attaching great importance to R&D investment. The group's testing center has passed the CNAS laboratory certification and continues to carry out rigorous testing work on metal powder coating products. The 180° extreme bending failed to swallow the light, and the 1,000-hour accelerated aging did not dim the luster; Excellent impact resistance, so that it will not fall off or crack under 4x magnification...... Whether it is acid rain washing, salt spray immersion, or damp heat erosion, the coating of VIE metal powder coating is always durable and inextinguishable, with a "steel-like" will, to complete the mission of transmitting light.

At a time when environmental protection requirements are becoming increasingly stringent, the Ministry of Ecology and Environment issued the "Opinions on Strengthening the Environmental Impact Assessment of Construction Projects Involving New Pollutants in Key Industries", which is like a bombshell, causing a strong shock in the powder coating industry. This "test" not only tests the compliance ability of enterprises, but also quietly reshapes the competitive pattern and development logic of the industry, prompting the powder coating industry to embark on the road of change from "passive compliance" to "active transformation".   New Pollutants: A "Must-Answer Question" for the Powder Coating Industry New pollutants, as chemical substances with biotoxicity, environmental persistence, bioaccumulation, etc., but have not yet been included in routine environmental management, are clearly included in the scope of control by the Opinions. The 14 categories of substances in the "List of Key Controlled New Pollutants (2023 Edition)", the list of toxic and harmful pollutants and the annexed substances of the "Stockholm Convention" have all become the key objects of control, and the provisions of "construction projects that do not meet the requirements of new pollutant control will not be approved" have drawn a strict red line for the powder coating industry.   The triple pressure of raw materials, processes and costs From project approval to production, the impact of new pollutant control policies on the powder coating industry is everywhere. During the project approval process, new construction, renovation or expansion projects involving the production or use of new pollutants prohibited in the list will be directly rejected, and the expansion plan of traditional solvent-based powder coatings containing high VOCs or other prohibited substances will be blocked. At the source of production, enterprises must start from the selection of raw materials and process optimization to reduce the generation of new pollutants, and the traditional production mode that relies on heavy metal additives or solvents that are easy to release persistent organic pollutants needs to be changed urgently. In terms of emission and monitoring, enterprises need to ensure that new pollutants are stably discharged up to standards, included in the management of pollutant discharge permits, and regularly carry out self-monitoring of substances that meet the monitoring conditions to accept real-time supervision. This series of measures has completely broken the inherent model of "focusing on end treatment and light source prevention and control" in the powder coating industry in the past.   However, the implementation of policies has also brought many challenges to enterprises. When it comes to raw material procurement, companies have had to abandon their price-driven sourcing strategy in favor of rigorous "environmental audits" of suppliers, which not only cost a lot of time, but also face a shortage of high-quality raw materials and rising procurement costs, as evidenced by the fact that environmentally friendly resins are 10% to 20% more expensive than traditional products. In terms of production process, in order to meet the requirements of new pollutant emission reduction, enterprises must upgrade technology, and the transformation of waste gas treatment process and formula adjustment require a lot of capital and technology, and the cost of a single production line transformation is as high as millions of yuan. In terms of environmental monitoring, the establishment of a whole-process monitoring system has led to a continuous increase in the compliance costs of enterprises in terms of equipment purchase, staffing and third-party entrustment, and the annual monitoring and compliance costs of small and medium-sized enterprises are expected to increase by 30% to 50%.   Opportunities in the crisis: green transformation activates new momentum for the industry But crises often go hand in hand with opportunities. The green transformation has brought new development momentum to the powder coating industry. Green products have gradually changed from "compliance just needs" to "market selling points", and environmental protection products such as water-based powder coatings, high-solids powder coatings, and heavy metal-free additives systems have become R&D hotspots, and the order volume of a leading enterprise has increased by 40% year-on-year after the water-based powder coating production line has been put into operation. In terms of brand premium, companies that have passed the new pollutant control certification can turn their environmental protection advantages into market competitiveness and gain a higher market share in specific market segments. In the field of technological innovation, the industry-university-research cooperation between enterprises and universities and scientific research institutions has been deepened, and the new technologies jointly developed not only improve the efficiency of pollutant treatment, but also reduce costs, and promote the development of the industry in the direction of high-end and intelligence.   How can enterprises hand over the "green answer sheet"? In the face of the challenges and opportunities brought by the control of new pollutants, powder coating companies should take the initiative to find a way to break the situation. Strengthen internal management, establish a whole-process management system, set up a full-time environmental protection department, and build a solid line of defense for environmental protection through digital tracking and employee training. Increase R&D investment, invest 3%-5% of annual revenue in environmental protection technology R&D, participate in the formulation of industry standards, and control the right to speak. Deepen policy coordination, take the initiative to connect with ecological and environmental departments and industry associations, share technical experience, and reduce transformation costs. Tell the "environmental protection story" well, convey the concept and results of environmental protection to customers and society in a variety of ways, and enhance brand value. The Ministry of Ecology and Environment's "New Pollutant Control Order" is a comprehensive inspection of the powder coating industry, and it is an important opportunity to promote the upgrading of the industry. Those companies that can break through in this green test will surely occupy a favorable position in the future wave of green economy and reap policy dividends and market share. When "green" truly becomes the background color of the powder coating industry, the industry will also usher in a new future of high-quality development.

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.