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With the increasing attention and attention of the state and society to the environment, the national air control and prevention plan and the local air VOC emission limits have been introduced, which strictly restricts the emission of three wastes in the automobile coating industry. The comprehensive performance of powder coating is higher than that of paint, and it has become the mainstream to replace liquid coating. Adhesion is an important technical index related to the mechanical properties, corrosion resistance and weather resistance of coatings. Based on the characteristics of the cabin itself and its coating process, powder coatings differ from traditional paints in controlling the adhesion of coatings. In this paper, the situation of powder coating technology promoted by automobile interior coating line is introduced, the factors affecting adhesion are discussed in detail, and the control methods and improvement measures are proposed. 1. Characteristics of the carriage coating process The process of powder coating process for automobile compartment is as follows: the upper part is → wiped→ degreased→ washed with water→ surface adjustment→ phosphating → washed with water→ pure water washing→ electrophoresis→ UF (ultrafiltrate) cleaning→ pure water washing→ electrophoresis drying→ grinding and wiping→ gluing → wiping before powder spraying→ powder spraying→ drying → inspection→ fine → repair → the next parts.      Table 1 compares the painting process of the carriage with other products, such as frames and appliances. It can be seen that compared with other workpieces, the process of powder coating of the carriage is the most complete. In the "composite coating" process, which is a "multi-process" process, it is necessary to ensure a balance of adhesion between each coating, taking into account the compatibility between each process. 2. Factors affecting the adhesion of powder coating  The powder coating is solvent-free and bakes directly into a film in an "all-solids" state. Compared with liquid coatings, the liquid wetting time is shorter in the film-forming process, the baking time in the glue state is longer, the baking temperature is higher, the coating is thicker, and the dry film cohesion is greater.   According to GB/T9286–1998 "Scratch Test of Pigment and Varnish Paint Film", the adhesion of the coating after each process was checked in the laboratory to investigate the influence of each process on the adhesion.  2.1 Pre-treatment process    2.1.1 Wipe clean   The surface condition of the steel plate affects the adhesion. The oxide film on the surface of the cabin substrate has a weak bond with the metal, which makes the subsequent coating easy to stick off and peel off. Therefore, the workpiece needs to be polished by manual grinding to wipe the oxide scale or shot blasting before painting.   2.1.2 Degreasing    The surface tension of oil stains is low, and its adhesion to metals and coatings is very weak, which has a great impact on adhesion. The degreasing process mainly includes pre-degreasing, degreasing, etc., and the low concentration of the liquid medicine, the pH change, the process temperature is not up to standard, and the treatment time is too short. In addition, the anti-rust oil on some plates is particularly difficult to remove, so it is necessary to verify before choosing anti-rust oil, and qualified oil can be used.    2.1.3 Tone      Abnormal surface conditioning process parameters will lead to large crystalline particles and loose film layers, which will seriously affect the adhesion of powder coating.    2.1.4 Phosphating    The phosphating process is an important factor affecting adhesion, and its control parameters include total acidity, free acidity, accelerator concentration, bath temperature, phosphating time, etc. The workpiece of the carriage is generally phosphated by ternary zinc, and the temperature is usually controlled at 40~55 °C, and the time is 2~3min.   When the parameters change, such as the temperature of the bath liquid is too high, the phosphating reaction is violent, the effective ion content will be lost, resulting in irregular crystallization and even secondary crystallization, and the obtained phosphate film particles are seriously large, sparse and not dense, and finally the adhesion between the phosphate film and the substrate will decrease. Spraying powder coating or electrophoretic coating (i.e., single coating process) directly on the phosphate film generally has a wide range of requirements for phosphating quality, the crystal particle size of the phosphate film is 5~25μm, and the adhesion of the coating film can be guaranteed when the film thickness is 1~10μm.   However, when examining the adhesion of different supporting systems (see Table 2), it was found that the adhesion of the "electrophoresis + powder coating" system was unqualified when the phosphate film thickness was about 9 μm. The test proves that the system has stricter requirements for the thickness and crystallization state of the phosphate film, and the adhesion of the final product can only be guaranteed when the crystalline particle size is 5~10μm and the film thickness is 1~3μm.   2.2 Electrophoresis  2.2.1 Compatibility between electrophoretic paint and powder coating  Electrophoretic paint can be divided into standard type and weather-resistant type according to the weather resistance level. Standard electrophoretic paints are usually based on epoxy resin with good corrosion resistance, and its free polar groups can react with the powder coating to form chemical bonds, so there is good adhesion between the two. The resin of weather-resistant electrophoretic paint is mainly composed of epoxy, polyester and acrylic resin, because the surface tension is different, the resin with large surface tension sinks in the lower layer during film formation, and the acrylic resin with low surface tension floats on the surface, and there is no active group to cross-link with the powder coating of the upper layer, so the adhesion between the two is poor. Before selecting a weather-resistant electrophoretic paint, it is necessary to verify the compatibility with the powder coating.    2.2.2 High temperature resistance of electrophoretic paint    The drying conditions of powder coating are (180~190)°C×20min, while the drying conditions of electrophoretic coating are usually (160~170)°C×20min, if it is baked at (180~190)°C×20min, it may be over-dried, and there is a risk of poor adhesion to powder coating.   Therefore, it is necessary to verify the high temperature baking resistance of the electrophoretic coating to ensure that it performs well at 190°C×60min, and the adhesion to the powder coating is still grade 0 after drying.   2.2.3 Drying conditions of electrophoretic paint    The adhesion of the powder coating to the electrophoretic coating is stronger than that obtained by the pretreatment, and once the electrophoresis layer is not dried enough, it is easy to engage with the upper coating, but when the drying time is set too long or the temperature is set too high, the electrophoretic paint will be over-cured, and the surface tension will increase, resulting in the adhesion of the powder coating on the electrophoretic layer will decrease.     After online pretreatment and electrophoresis, the test plate is dried under different conditions, and the dryness is detected and then the on-line hanging plate is sprayed with powder, and the powder coating thickness is controlled to 100~120μm.   2.3 Powder coating  2.3.1 Powder coating process parameters  Using electrostatic spraying, the final process parameters used in the field are as follows: gun distance 20~40cm, voltage 50~80kV, current 10~40μA, powder output 100~300 g/min. After debugging multiple rounds of process parameters, it was found that the construction parameters only affected the utilization rate of the paint and the one-time powder rate, but did not affect the adhesion.   2.3.2 Selection of powder coatings      Although powder coating has been maturely used in home appliances, auto parts and other fields for many years, due to the particularity of the cabin coating, the powder coating used is self-contained, which has higher requirements than other industries.   2.3.3 Powder coated film thickness    When the coating is formed on a rigid substrate, it can counteract adhesion due to the internal stress caused by the inability to shrink, and only a small external force is required to break the bond. If the film layer is too thick, the internal shrinkage force will have a strong peeling effect on the lower coating, which will affect the adhesion between the coatings and the substrate.   When the powder coating model remains the same, the thicker the film layer, the greater the internal stress, and the worse the adhesion. As a rule of thumb, the powder coating thickness is controlled below 160 μm, and the adhesion can be stabilized at class 0. And the car compartment mostly adopts corrugated plate, there are more concave and convex surfaces, and the thickness distribution of powder coating is uneven, so it is recommended to control the film thickness of the concave surface to meet the requirements of low engineering covering power, generally 70~80μm; The convex surface is closer to the powder spraying gun, and the powder amount will be higher, and the film thickness can generally reach 120~130μm.   2.3.4 Factors influencing the curing of powder coatings     Insufficient curing time and drying temperature will cause the coating to become more brittle, which will peel off when the adhesion is tested. Therefore, in order to ensure that the adhesion of the coating meets the standard, it is necessary to track and monitor the furnace temperature curve at the production site and check the adhesion at this temperature.   2.4 Key points of production control of powder coating line 2.4.1 Pretreatment line groove fluid    The production site needs to monitor the bath parameters once per shift to monitor the debinding status, temperature, degreasing alkalinity, phosphating parameters, and ion content in the phosphating solution. At the same time, the pretreatment material manufacturers are required to provide on-site services and provide weekly reports on ion content testing.   2.4.2 Electrophoresis drying state    Check whether the electrophoresis oven and conveyor equipment are in line with the process status every day, and regularly wipe with absorbent cotton dipped in acetone to test the dryness of the electrophoretic paint film. During the process debugging and trial production, the first article is used with a breadboard every day to check the adhesion of the electrophoresis layer and powder coating, and then produce after passing the test. After stabilization, it can be changed to random baffle detection.    2.4.3 Furnace temperature   Once a week, the furnace temperature curve of the electrophoresis and powder drying furnace is checked by a furnace temperature tracker, and the adhesion of the coating at this temperature is tested.    2.5 Solutions to powder coating adhesion problems at the production site   After the powder production line is put into use, under the condition that the coating is well matched and the equipment status meets the process requirements, once there is a problem of poor adhesion, the cause of the problem can be quickly determined and solved by the following methods on site.   2.5.1 Powder anomalies    The powder is sprayed directly on the standard pretreatment plate and baked in a small laboratory oven to determine whether the powder is abnormal.   2.5.2 Pretreatment and electrophoresis abnormalities    Pretreatment fluids and electrophoretic paints are provided by different suppliers, and it is difficult to immediately determine the source of the problem if there is an abnormality in production. The "standard phosphating plate" can be used in commissioning production, which can be directly electrophoresed and then sprayed with powder coating, and then the adhesion can be evaluated.   If it is qualified, it means that there is an abnormality in the pretreatment process, and if it is not, it is the electrophoresis process. The method is simple, fast, effective, and reproducible, which can effectively troubleshoot problems and ensure mass production schedule.   2.5.3 Selection of detection tools      Replacing the scratching knife with a utility knife, stabilizing the utility knife with a steel ruler, and using a "test tape" such as 3M's Scotch4-1000 can effectively improve the accuracy of adhesion testing.   3. Conclusion      In order to ensure the quality of the final coating, this paper investigates the influence of each process on adhesion according to the process flow, and gives the control points and solutions, which provides a certain reference for other factories to promote this process.

The classic "summer pairing" of barbecue and cold drink makes us feel the beauty and fireworks of life.   A well-designed barbecue is not only a powerful tool for cooking delicious food, but also the key to enhancing the quality and atmosphere of this summer feast.   If you want to do a good job, you must first sharpen your tools. Wan'an oven uses high-temperature resistant powder coating, with every place to pay attention to, to achieve every gathering, fearless summer flames, and to break into the sweet and sour food rivers and lakes.     During the operation of the oven, its internal temperature rises sharply. Without the protection of the temperature-resistant coating, the oven substrate will be directly exposed to open flames and high temperatures, causing irreversible damage such as softening and deformation of the material, and making the carefully prepared summer feast of the tongue come to naught in an instant.   In response to the demand for coating the parts of the oven that are in direct contact with the open flame, WANAN has devoted itself to research and development, and has launched high-performance high-temperature powder coatings for ovens that are both temperature-resistant and scratch-resistant. After pretreatment such as iron phosphating and sandblasting on the surface of the oven product, the cured coating can stably withstand the temperature resistance of 200-500°C.   Even if it is exposed to extreme conditions such as high temperature open flame and frequent physical friction for a long time, the coating of WANAN oven high-temperature powder coating can still maintain its original luster, and will not lose its color and the coating will not fall off.     When cooking food, the inner cavity of the oven will be directly exposed to steam, oil and salt infiltration and high temperature open flame, and the safety and durability of its coating materials are directly related to food safety and the stability of the oven.   The coating of high-temperature resistant powder coating for Wan'an oven has dense coating, high adhesion, excellent stain resistance and easy cleaning ability, and can form an anti-corrosion and wear-resistant protective "barrier" on the surface of the oven product.     In the harsh neutral salt spray test environment, WANAN high-temperature resistant 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, which ensures that the product can effectively resist the erosion of oil, salt, water, acid, alkali and other substances in practical applications, and can keep the surface of the oven smooth and clean even in the face of long-term cooking challenges, so that delicious and safe coexist, and let joy and health go hand in hand.     With the leap in people's quality of life and the emphasis on leisure and entertainment activities, the oven is not only a cooking tool, but also a display of atmosphere creation elements and personal life taste in barbecue parties, outdoor gatherings, and festival celebrations.   With a variety of colors, delicate textures, and rich gloss, WANAN high-temperature powder coatings for ovens can better meet the needs and aesthetic preferences of different user groups, and achieve the perfect combination of function and aesthetics.   Compared with the traditional coating process, powder coating can achieve several or even more than a dozen coating effects of traditional paint at one spraying, and 360° spraying molding without dead angles can meet complex shapes such as planes and curved surfaces, providing a higher degree of design freedom for oven product design. The exquisite oven and the delicious food complement each other, making every cooking and tasting a feast for the eyes and the palate.     In 2019, WANAN launched the research of high-temperature resistant powder coating project and achieved a series of results, including 1 new new high-temperature and strong weather-resistant powder coating product, 3 national authorized invention patents, and 1 group standard.   The Zhongguancun Materials Testing Technology Alliance (CSTM) group standard T/CSTM 00640-2022 "High Temperature Powder Coatings for Ovens" led by WANAN Group was officially released on August 29, 2022 and implemented on November 29, 2022. Through the formulation and implementation of this standard, WANAN Group has broken the monopoly of foreign companies on domestic high-temperature powder coatings, and opened up a new track for domestic high-temperature powder coating production.   In this hot summer, you can't get a cold drink without a barbecue around the oven, and you can't have two meals......   WANNAN Group has always been committed to providing customers with one-stop solutions, continuing to create maximum value for customers, and achieving every summer trip with every hot and cool intertwined taste.

Introduction With the advent of summer, powder agglomeration is a headache for the majority of manufacturers, in addition to the process problems in the production process, storage and transportation are also factors that affect the final spraying effect. In summer, the temperature is high and the humidity is high, and the temperature and humidity can directly affect the final coating quality of the powder coating.   Many customers have high requirements for the utilization rate of powder, and the powder loading rate is the most specific manifestation of the utilization rate. There are many factors that affect the powder loading rate, such as resin content, particle size, fluidity, resin type and so on.One of the most important factors affecting the powder loading rate is the electrification of powder coatings.    This kind of problem is a system engineering integrating materials, formula design, and application, and each manufacturer also has different ways to solve it, so we will not discuss it for the time being. Today, I would like to recommend an additive for you, which can greatly improve this kind of problem.   【Hydrophobic type】fumed nano alumina Alu C-S Alu C-S is a nano-alumina that has been hydrophobically modified on the surface. It has finer particles, better flowability, and better compatibility with resins. When applied to medium and high-grade powder coatings, it can achieve a comprehensive improvement of fluidity and electrostatic spraying performance, and play a role in preventing agglomeration.   The role of fumed alumina in powder coatings 1. Anti-caking: nano-level (13 nanometer native particle size) powder and unique structure and chargeability can prevent caking.   2. Improve fluidity: due to the unique positive charge characteristics and unique structure, it plays a good role in fluidity.   3. Improve wear resistance: Alumina has a high hardness and can play a good wear resistance effect.   4. Improve the powder loading rate: the positive charge of fumed alumina makes it an effective additive for the formulation of frictional charged powder coatings. Whether it's epoxy polyester blends, polyester-TGIC or other resin systems, fumed alumina offers an excellent combination of fluidity and electrical charge in friction coating applications;   5. Improve the compactness of the coating.    The fluidity of the positive charge of fumed alumina in powder coatings and the mechanism of improving the upper fraction Powder aggregation is the result of the internal structural forces of the material competing with the gravitational forces on the particles in a variety of ways, depending on particle size, humidity and particle composition.   In general, when the size of the dry particles is greater than 75um, the gravity force is greater than the structure or the inter-particle force, the gravitational force between the particles is small, the powder can be fluidized, and only a small amount of energy is needed to flow, and the particles can move independently of each other. However, when the particles are large, the appearance quality of the coating film decreases, and the orange peel is also more serious, and the quality of the sprayed surface is reduced.   When the powder particles are less than 75um, the gravitational force between the particles is often greater than the gravity of the particles, and the powder is easy to agglomerate, resulting in a decrease in fluidity.   At present, the powder coating particles are basically about 35um, and the future development trend is to further control the size of the powder particles between 10~20um to obtain a thinner coating by reducing the size of the matrix particles.   In order to overcome the agglomeration between powders, it is necessary to add nanomaterials such as fumed alumina to play a role in promoting fluidity. An appropriate amount of alumina powder is added to the powder coating, and through sufficient mechanical stirring, the alumina nanoparticles can be orderly combined on the surface of the matrix particles to form a layer of "coating".   In this way, a "shell core" structure is formed, and the whole movement can effectively reduce the electrostatic attraction between the particles, and avoid powder adhesion due to van der Waals force, moisture absorption, particle friction, etc.   Fluidization requires less energy, less sedimentation occurs during transport, powder fluidity is better, and powder fluffiness density increases.   If too much or too little alumina is added or due to insufficient stirring, then the nano alumina particles can not be evenly combined on the surface of the matrix particles, but randomly distributed between the matrix particles, and can not form an effective "coating" on the surface of the matrix particles, then the powder coating particles will also agglomerate, resulting in reduced fluidity, the matrix particles tend to agglomerate, fluidization requires more energy, and it is not convenient for construction spraying.   It is precisely because of the unique structure of fumed alumina and the appropriate size of the "agglomerate" particles and the electropositivity of the surface that it can form a coated "shell core" structure with the matrix particles of the powder coating, thereby effectively improving the fluidity of the powder coating, and also providing the possibility for further refinement of powder coating particles in the future, especially the ultra-fine powder coating currently appearing in the market, and the particle size of the product is even controlled to 0.1~0.2um.   The smaller the powder coating particles, the lower its heat capacity, and the less time required for melting, so that it can coalesce quickly to form a film and then level, the coating is dense, adhesion, impact strength and toughness are good, the corner coverage is high, and it has excellent chemical corrosion resistance and electrical insulation performance.   Generally, the amount of fumed alumina is 0.1%~0.3% of the total mass of powder coating, which can be mixed before and after crushing. If the addition amount is too much, the appearance and mechanical properties of the coating film will be affected, and the fluidization effect will not be obvious if the addition amount is too small. In addition, it is necessary to mix well when adding.   Special advantages of hydrophobic fumed alumina 1. It has all the advantages of hydrophilic alumina;   2. Due to hydrophobic treatment, the fluidity is greatly improved, and the anti-caking ability is greatly improved;   3. The charge is more stable, and its hydrophobic characteristics make it difficult for moisture in the air to enter and take away the charge;   4. It reduces the agglomeration of gas and aluminum itself, and greatly reduces the probability of white spots.

Thousands of high-rise buildings, focusing on the foundation, a journey of a thousand miles, starting with a single step. As the last process of automobile manufacturing, the painting process has a decisive impact on the quality of the whole vehicle. Especially for automobile wheels, the quality of coating directly affects the service life of automobile wheels, which is the key link to achieve the harmony and unity of automobile driving performance and design appearance. Wanan Group has been deeply involved in the field of powder coatings for more than 20 years, and has always been committed to providing high-quality and efficient coating solutions for the automotive industry, effectively protecting the wheel hub from the external environment, giving the vehicle a unique visual appeal, and making every painted car show extraordinary performance and charm.   The service life of each car is inseparable from the auto parts, and the quality of the vehicle wheel hub is related to the personal safety of every car owner.   Wanan Group has successfully passed the IATF 16949 automotive industry quality management system standard certification, with perfect control standards, marking that VIE Group's professionalism, standardization and effectiveness in automotive powder coatings have been recognized by the International Organization for Standardization.     In 2021, Wanan Testing Center officially obtained the CNAS Laboratory Accreditation Certificate, and in 2023, it passed the review and expanded the scope of testing, further consolidating the Group's technological leadership.   Wanan Testing Center continues to carry out rigorous product testing, and the powder coatings for VIE automotive produced by Wanan can well meet the coating needs of automotive wheels such as weather resistance, chemical resistance, scratch resistance, corrosion resistance, and impact resistance, escorting every safe trip.   As an integral part of the appearance of the car, the design style of the wheel hub directly affects the visual effect of the whole vehicle, and its design aesthetics is an important consideration in the decision-making process of consumers.   Aluminum profiles have strong plasticity and machinability, and can be processed into complex shapes such as planes and curved surfaces through extrusion, cutting, welding, etc., providing a higher degree of design freedom for modern wheel shapes.     Wanan Group has deeply researched the surface coating process of aluminum wheels, 360° spraying molding without dead angles, and provides complete and seamless decorative surfaces for various complex shapes of wheels.   Guided by customer needs, tailor-made with customized coating appearance, including color matching, gloss, texture and other special effects, allowing designers to achieve modeling creativity with higher design freedom and flexibility, and provide a more fashionable and beautiful appearance for the wheel.   With the continuous improvement of China's green development requirements, "paint to powder" is an inevitable trend. Energy conservation and emission reduction is the main theme of the long-term development of the automotive industry, and the Ministry of Industry and Information Technology issued the double integral management method in 2017 pointed out that lightweight is the best choice for automobile energy saving.   In the field of coating, powder coating is widely recognized by the market as "4E" environmentally friendly green coating because of its characteristics of no pollution, zero VOCs emission, high recycling rate, simple coating process and high automation. Not only can VOC emissions be reduced, but also the carbon footprint of the product life cycle can be reduced.   Compared with traditional automotive coatings, Wanan automotive powder coating is lighter and thinner in one spray molding, saving the amount of paint and spraying paint can be recycled, with a recovery rate of more than 99%, providing environmental protection coating for the automotive industry to reduce costs and increase efficiency.   Wanan Group will continue to uphold the persistent pursuit of quality, driven by innovation, and take environmental protection as the responsibility, to provide better coating solutions for the automotive industry, and continue to create maximum value for customers.   Great oaks from little acorns grow.. VIE has always walked with the market to provide a solid guarantee for safe travel every way.    

Process requirements for aluminum alloy materials in coating 1.1 Coating process   Aluminum alloy material coating is a systematic project, mainly including the surface treatment before coating, material coating and curing and leveling three basic processes, it is necessary to select the appropriate process conditions, ensure good working environment conditions and ensure quality supervision, technology in place, and consider the economy and other important links. The process flow is: washing→ degreasing→ washing→ washing→ pure water washing→ passivation treatment→ washing → washing→ pure water washing→ water drying→ hanging material → spraying→ curing → unloading → inspection packaging.   1.2 Pretreatment process   Surface pretreatment is the preparation work on the surface of aluminum alloy materials, to remove foreign objects (such as dust, oil, aluminum chips, etc.) on the surface of the material, to ensure that the resulting film layer has good adhesion, corrosion resistance, decoration, and to provide a good coating material suitable for coating requirements. The biggest advantage of this process is that it is environmentally friendly, free of polluting substances, and has high efficiency, low cost and stable quality of passivation layer. The pretreatment process index control is not up to standard or the operation is not standardized, which will cause many quality problems, and the more serious thing is that the adhesion of the coating is unqualified, and the surface paint film will gradually fall off after a period of use. There are five main causes of such defects.   1.2.1 Skim is not clean   Improper degreasing will lead to problems such as oil stains, too low etching amount or incomplete removal of the natural oxide film on the surface of the aluminum alloy material, which cannot be passivated normally. The experiment shows that the degreasing and dust removal are not clean, and the coating will fall off the surface after spraying.   1.2.2 Passivation cell Al3+ concentration   The effect of Al3+ concentration in the passivation tank on the adhesion of the coating to boiling water is shown in Figure 1. As can be seen from Figure 1, in order to ensure 100% compliance with the coating adhesion, the concentration of Al3+ in the passivation tank must be controlled within 0.2g/l. In order to better verify the results of this experiment, we conducted several strong impact tests in the laboratory. The results show that when the concentration of Al3+ in the passivation tank exceeds 0.2g/l (0.3~0.4g/l), the surface coating begins to fall off after the passivated aluminum matrix is coated and the impact resistance test is done, and the adhesion is unqualified. The crystalline phase observation of the passivated matrix with different Al3+ concentrations showed that the surface of the treated matrix showed a regular hexagonal structure and was dense at low concentrations. On the contrary, although it also has a hexagonal structure, it is sparse.   1.2.3 Conductivity and pH of the last pure water wash   The effect of the conductivity of the last pure water wash on the adhesion of the boiling water of the coating is shown in Figure 2, and the effect of the pH value of the last pure water wash on the adhesion of the boiling water of the coating is shown in Figure 3. As can be seen from Figure 2 and Figure 3, in order to ensure that the adhesion of the coating is 100% qualified, the conductivity of 9# pure water washing must be < 80μs/cm and the pH value must be > 4.5. In order to better verify the results of this experiment, we conducted several strong impact tests in the laboratory. The results show that after the last pure water washing with different conductivity and pH, the impact resistance test of the cleaned aluminum matrix is carried out, and the degree of peeling off of the surface coating is different, which verifies the accuracy of the results of this project.   1.2.4 Storage environment and storage time after passivation   Because the passivation film is thinner and the corrosion resistance is much lower than that of the hexavalent chromium passivation layer, it should be sprayed in time after passivation to prevent the passivation film from corroding caused by being placed in the plant. Especially in the case of small plant or poor ventilation, the corrosive gas in the plant will accelerate the corrosion of the passivation film. Practice shows that the passivated aluminum is best sprayed on duty, and the placement time under special circumstances cannot exceed 24 hours.   Problems that should be paid attention to in aluminum alloy coating   To meet the reasonable matching of various properties, it is necessary to adopt advanced forming technology, optimized pretreatment process and advanced extrusion process through reasonable composition design, including composition optimization and fine-tuning; The integration of many technologies such as reasonable structure, grain size, uniform distribution of the second phase and size control can produce automotive aluminum alloy materials with good performance. The development direction of aluminum alloy materials is mainly to improve strength, improve formability and reduce costs. conclusion   Through the research of this subject, we have mastered the common powder coating (including pretreatment) process technology of aluminum alloy materials, and improved it on the basis of traditional technology, which is more environmentally friendly, green, efficient and high-quality, and has a great role in promoting the research and development, promotion and product transformation of new aluminum alloy materials.    

Traditional Chinese colors are not only an accurate interpretation of the beauty of nature, but also a bond with all things in the world. In the eyes of the ancients, the beauty of traditional Chinese colors is deeply rooted in the natural time sequence, and the four seasons, the solar terms, and the withering of plants and trees can all depict their vividness and agility through color.     In WANAN's color universe, with the turn of time, the rise and fall of color is also in the ever-changing. WANAN uses powder paint as a pen to paint the colorful five-color moments, each color embodies our awe and love for nature.     When the morning light is slightly dewed, a red glow spreads at the end of the earth. The morning glow is full of red, and it is the first good morning greeting from the sky to the awakening city.     Red is the color of the morning glow, a color with strong vitality, and a representative color of a sense of strength. Wan'an red series of powder coatings freeze the color of the red like the morning glow of the fire, the natural sincerity and enthusiasm into life, is an excellent interpretation of the force and beauty in the field of construction machinery, widely used in bulldozers, excavators, rollers and other parts of the coating, to give construction machinery an endless sense of strength.     In the quiet of the morning, the mist covered the land like a light veil. The green mountains loom in the misty clouds, painting a fairyland-like ink painting of the earth.     The hustle and bustle of daily life always disturbs the soul, and only when you return home can you feel a relaxed and comfortable atmosphere. The appropriate white space of the indoor furniture carries a sense of relaxation after being busy. Wan'an white series powder coating freezes the lightness and elegance of clouds and mist with color, so that the poetry and painting of nature shine into reality, bringing more relaxation space to life.     The sun is rising, and the first rays of golden light in the morning pierce the sky, quietly waking up the sleeping world. Every sunrise is a new beginning, a symbol of hope, and the most beautiful gift that nature has given us.     The energetic WANAN yellow series powder coatings convey a positive attitude towards life and are widely used in household appliances and cabinets. Each touch of intense yellow is full of WANAN's expectations for a better life, inspiring us to go to the future with an optimistic and positive attitude.     The first breeze of the morning blows across the earth, waking up the sleeping plants and trees, and a beautiful day is quietly "sprouting".     The WANAN green series powder coating freezes the color of vibrant plants and trees on the substrates such as profiles, glass, and plastic steel, and paints a beautiful and fresh natural background color for the field of building materials. With fresh colors rooted in nature, it conveys the healing energy of nature.     There are 24 solar terms in a year, 12 hours a day, every season, every day, every hour, there are moving colors everywhere. WANAN powder coats the beauty of time with color, and reproduces the gorgeous colors of the time in the form of products, showing the infinite charm of time; With the color aesthetic concept of "color without boundaries", every moment of life is full of unique and charming brilliance.  

Powder coating is widely used in various hardware and software in our lives, such as: aluminum profiles, small household appliances, mobile phones and computers, dining seats, children's toys, kitchen utensils, sports equipment, Wujinjiaodian, indoor and outdoor buildings, photovoltaic equipment, large, medium and small cars, high-speed rail, aircraft, military materials and new energy fields, etc., which are widely used in all workpieces needed in our lives. The performance requirements in low-temperature powder coating are mainly reflected in the high-temperature curing of 180 °C-220 °C (low temperature understanding: 110 °C-150 °C) that no longer requires traditional powder coatings, and the specific performance of low-temperature powder coating is reflected in: food-grade non-toxic and tasteless, with special surface effect, scratch resistance, high hardness, aging resistance, yellowing resistance, no VOC, no formaldehyde, no heavy metals, no BPA, waterproof, moisture-proof, mildew-proof, stain-resistant, easy to clean, colorful and multi-colored, How to improve the quality of low-temperature powder coating again in the later stage, using advanced coating equipment and technology, and how to adapt to the development of low-temperature powder coating still need a long way to go for the industry. The requirements for coating in the furniture industry are also getting higher and higher, and the current consumers' requirements for indoor furniture are also odorless furniture and furniture products with zero VOC volatilization. So we have also seen this development phenomenon, and in recent years, many large enterprises have fully used low-temperature powder coating products.   The "low-carbon economy" is an economic model based on low energy consumption, low pollution and low emissions, and is another major progress of human society after agricultural civilization and industrial civilization. The essence of the "low-carbon economy" is the efficient use of energy, the development of clean energy, and the pursuit of green GDP, and the core is the fundamental transformation of energy technology and emission reduction technology innovation, industrial structure and institutional innovation, and the concept of human survival and development. The concept was first introduced in government documents in 2003 in the UK's Energy White Paper, Our Energy Future: Creating a Low-Carbon Economy. However, it was not until the 2009 Copenhagen climate conference that the "low-carbon economy" jumped back into people's attention and gained attention. In 2011, "low-carbon and energy-saving" will become a new concept of environmental protection for powder coating enterprises. The traditional powder coating industry is considered to be a large consumer of energy and carbon emissions, and has great potential for energy saving and carbon emission reduction. "Low carbon" means that not only the coatings produced are green and environmentally friendly, but also the principle of low energy consumption must be adhered to in the selection of raw materials and the production process. The low-temperature powder coating industry will transform from the traditional high-temperature powder coating industry to a modern industrial branch with high technology and low energy consumption.   10 years of low-temperature powder coating industry is almost over, low-temperature powder coating enterprises will go how far and how high, in fact, it depends on the enterprise itself in research and development, production and manufacturing more persistence, the application of low-temperature powder coating may be far more exciting than the author predicted, everything depends on the research and development progress of our coating chemical industry doctoral elites, the author will be with the elites of the coating industry looking forward to another better year for the low-temperature powder coating industry.

The Dragon Boat Festival is a traditional Chinese festival that is usually celebrated on the fifth day of the fifth lunar month. There are many traditional sayings about why you should eat zongzi, and here are a few of the common explanations:   Commemoration of Qu Yuan: The most widely accepted theory is that zongzi was eaten in honor of Qu Yuan, a patriotic poet in ancient China. It is rumored that Qu Yuan was a minister and poet of Chu during the Warring States Period, who was treated unfairly because of his loyalty to the country, and eventually committed suicide by throwing himself into the river to express his anxiety and helplessness for the country. In order to prevent fish and shrimp from eating Qu Yuan's corpse, people threw various foods into the river, including glutinous rice wrapped in dumpling leaves. Later, this custom gradually evolved into the tradition of eating zongzi.     Ward off evil spirits and avoid epidemics: Another theory is that the fifth day of the fifth month of May is the time when yang energy is at its peak, and this time coincides with the most rampant viruses and evil spirits. Folks believe that eating zongzi can drive away evil spirits and avoid epidemics and protect the body from diseases. Because of the special aroma of the outer layer of zongzi leaves, zongzi is believed to have the effect of warding off evil spirits.   Avoid spoilage: The fifth day of May is also the time when the weather gets hotter, which can easily lead to food spoilage. Traditional zongzi is made by wrapping glutinous rice and various fillings in zongzi leaves and then boiling or steaming them. This wrapping and cooking method ensures that the rice dumplings stay fresh for a longer time in the outdoor environment and avoid food spoilage.     In general, eating zongzi has become one of the important customs of the Chinese Dragon Boat Festival. Whether it's to commemorate Qu Yuan, ward off evil spirits or avoid corruption, eating zongzi is a way for people to reunite, celebrate, and pray for blessings during this festival. Zongzi has a variety of different tastes and practices in different regions and families, and is an indispensable part of traditional Chinese culture.

In the era of environmental protection storm, the development of environment-friendly coatings is the inevitable choice of enterprises, but environmentally friendly coatings are not only water-based coatings, if enterprises swarm to develop water-based coatings, it is inevitable that there will be product homogenization. In addition to water-based coatings, high-solids coatings, solvent-free coatings, and powder coatings are also environmentally friendly coatings, which should become the key development direction of the coatings industry. The general situation of powder coating 1. Introduction to powder coating Powder coating began in the 50s of the last century, is a solid content of 100%, and no organic volatile compounds (VOCs) produced by environmentally friendly coatings, with energy saving, pollution reduction, simple process, easy to achieve industrial automation, excellent coating performance and other characteristics. Powder coatings are powdered coatings composed of polymers, pigments, fillers, and additives. Because there is no volatilization of liquid medium, it has good ecological and environmental protection; Powder coating can form a thicker coating in one pass, which has extremely high production efficiency; The mechanical properties and chemical resistance of powder coatings are excellent, and they have excellent coating properties; The use of powder coating can save energy and resources, and the utilization rate can reach 99%, which is safe to use and has outstanding economy; Therefore, as a solvent-free coating, powder coating conforms to the internationally popular "four E" principles of economy, environmental protection, high efficiency and excellent performance. 2. Overview of the powder coating market With the growing demand for electrical appliances and light vehicles, the demand for powder coatings has increased. The growing demand from the end-use industry in developed and emerging countries is also triggering the growth of the powder coating market.   Thanks to the joint promotion of a number of factors, especially the rapid development of urbanization and the joint growth of housing, construction and automobiles, the growth rate of China's powder coating market demand ranks first in the world, and the rapid development of powder coating will inevitably drive the growth of powder filler demand. Analysis of the application of different powder materials in powder coatings Fillers in coatings can not only reduce their costs, but also play a great role in improving the performance of coating products. For example, improve the wear resistance and scratch resistance of the coating film, reduce the sagging of the coating when it melts and runs, improve the anti-corrosion performance, and improve the moisture resistance. Factors such as density, dispersion performance, particle size distribution, and purity need to be considered when selecting fillers for powder coatings. In general, the higher the density, the lower the powder coating coverage; The dispersion of large particles is better than that of small particles; The filler is chemically inert and avoids reacting with certain components of the powder formulation, such as pigments; The color of the filler should be as white as possible. The powder materials commonly used in powder coating mainly include calcium carbonate, barium sulfate, talc, mica powder, kaolin, silica, wollastonite, etc. 1. Application of calcium carbonate in powder coatings Calcium carbonate is divided into light calcium carbonate (precipitated calcium carbonate) and heavy calcium carbonate. Regardless of the type of calcium carbonate and the method used to produce it, different particle sizes strongly affect the gloss of the coating. In addition to being used for increment, heavy calcium is mainly used to partially replace titanium dioxide and color pigments, replace light calcium and precipitate barium sulfate, anti-corrosion and partially replace anti-rust pigments. When heavy calcium is used in interior architectural paints, it can be used alone or in combination with talcum powder. Compared to talc, calcium carbonate reduces the rate of chalking, improves color retention and increases mold resistance in light-colored paints. However, due to poor acid resistance, it hinders its application in topical coatings. Compared with heavy calcium, light calcium has a small particle size and narrow particle size distribution range, high oil absorption and brightness, and light calcium can be used where the maximum matting effect is required. 2. Application of barium sulfate in powder coatings There are two kinds of barium sulfate used as pigments for paint bodies: natural and synthetic, the natural product weighs spar powder, and the synthetic product is called precipitated barium sulfate. In powder coatings, precipitated barium sulfate can enhance the leveling and gloss retention of powder coatings, and has good compatibility with all pigments. It can achieve the ideal coating thickness in the spraying process and the powder application rate is high.   Barite powder fillers are mainly used in industrial primers and automotive intermediate coatings that require high film strength, high filling force and high chemical inertness, as well as in topcoats that require high gloss. In latex paints, due to the high refractive index of barite (1.637), fine barite powder can have the function of translucent white pigment, which can replace part of titanium dioxide in the coating. 3. Application of mica powder in powder coatings Mica powder is a complex silicate composition, the particles are flake-like, with excellent heat resistance, acid and alkali resistance, which has an impact on the melt fluidity of powder coatings, and is generally used in temperature-resistant and insulating powder coatings, and can be used as fillers for texture powders. Among the many mica-like minerals, the chemical structure of sericite is similar to that of kaolin, and it has a variety of characteristics of mica minerals and clay minerals. When applied in coatings, it can greatly improve the weather resistance and water permeability of the coating film, enhance the adhesion and strength of the coating film, and improve the appearance of the coating film. At the same time, the dye particles are easy to enter the lattice layer of sericite powder, so as to maintain the color for a long time. In addition, sericite powder also has the function of anti-algae and mildew. Therefore, sericite powder is a multifunctional filler with excellent price-performance ratio for coatings. 4. Application of talcum powder in powder coatings Talc, also known as aqueous magnesium silicate, is made by direct crushing of talc. The particles are needle-like crystals, have a slippery feeling, soft texture and low abrasiveness, have good suspension and dispersion and a certain thixotropy, which has a great impact on the melt fluidity of powder coatings, and are often used in texture powders. At present, it is used in various primers, intermediate coatings, road sign paints, industrial coatings and architectural coatings for interior and exterior use.   Talcum powder is inexpensive, but it has drawbacks and is therefore used in limited quantities. First of all, the oil absorption is larger. In the case of low oil absorption, it must be combined with fillers and barite powder with low oil absorption; Secondly, the wear resistance is not high, and other fillers should be added to make up for the occasion that high wear resistance is required; In addition, talcum powder containing other non-metallic minerals is not suitable for external coatings requiring high weather resistance because impurity minerals are easy to react with acids (such as acid rain); In addition, talc has matting properties, so it is generally not used in high-gloss coatings. 5. Application of silica in powder coatings Porous powder quartz is a kind of silica system, which is recognized as safe to use, and has been widely used in powder coatings, fire retardant coatings, waterproof coatings, anti-corrosion coatings, etc. Cheap porous powder quartz can reduce the cost of powder coatings, and at the same time replace barium sulfate to reduce the content of soluble barium in the product, which meets environmental protection requirements. In addition, fumed silica is often used as a loose and anti-caking additive for powder coatings. Fumed silica is a multifunctional pigment and a rheology control agent for coatings with excellent performance. In liquid coatings, its rheological control functions include: thickening, thixotropy, anti-sagging, covering edges; In solid powder coating systems, the free flow of powders is enhanced, and caking and fluidization are prevented. 6. Application of kaolin in powder coatings Kaolin can improve thixotropy and sedimentation resistance. Calcined clay has no effect on rheological properties, but can have the same matting effect, increased coverage and increased whiteness as untreated clay, which is similar to talc. Kaolin generally has high water absorption, which is not suitable for improving the thixotropy of coatings and is not suitable for the preparation of hydrophobic coating films. The particle size of kaolin products is between 0.2 and 1 μm. Kaolin with large particle size has low water absorption; Kaolin (less than 1 μm) with good matting effect and small particle size can be used for semi-gloss coatings and internal coatings.   Kaolin can be divided into calcined kaolin and washed kaolin. Generally speaking, the oil absorption, opacity, porosity, and hardness of calcined kaolin are higher than those of washed kaolin. 7. Application of hollow glass beads in powder coatings Hollow glass beads are a tiny, hollow spherical powder, which has the advantages of light weight, large volume, low thermal conductivity, high compressive strength, insulation, corrosion resistance, non-toxicity, dispersion, fluidity and stability. When used in powder coatings, hollow glass beads can do the following: (1) Low heat insulation, insulation, and water absorption. The inside of the hollow glass beads is a vacuum or thin gas, and there is a difference in density and thermal conductivity between the epoxy resin and the epoxy resin, so it has the characteristics of heat insulation, and is an excellent filler for high-temperature resistant powder coatings. (2) It can improve the physical and mechanical properties of powder coating. Hollow glass bead fillers increase the hardness and stiffness of powder coatings. However, the impact resistance decreases, and the decline is related to the surface treatment of insulating glass beads. Pretreatment with the right coupling agent can reduce the impact impact of the material. (3) Low oil absorption. The oil absorption rate of different types of hollow glass beads per 100g is between 7mg~50mg, and this low oil absorption rate filler material increases the filling amount in disguise during the production process and reduces the comprehensive cost. 8. Application of wollastonite in powder coatings The main component of wollastonite is calcium silicate, with a density of 2.9g/cm3, a refractive index of 1.63, and an oil absorption of 30~50%, which has a needle-like structure and good brightness.   Powder coatings are generally made of natural wollastonite powder, which is processed from natural wollastonite. Wollastonite can be used as a physical pigment and replace some white pigments in coatings, playing a role in covering and incrementing, and reducing the cost of paint. Because of its good electrical conductivity, it is often used in epoxy insulation powder coatings. Wollastonite has a white needle-like structure that improves the flexural and tensile properties of powder coatings. The development trend of powder fillers for powder coatings 1. Surface treatment of powder filler Powder coating fillers are polar, while powder coating resins are extremely polar, which will cause poor compatibility between the two, which will have a negative impact on powder coating processing and coating performance. Therefore, it is usually necessary to treat the powder filler by physical methods (surface coating and surface adsorption) or chemical methods (surface substitution, hydrolysis, polymerization and grafting, etc.), so that the particle diameter of the aggregate can be significantly reduced or the fluidity of the system can be improved, and the processing performance, apparent quality (such as gloss, color brightness, etc.) and mechanical strength of the coating can be improved. 2. Powder filler is fine When the ratio of powder coating resin to filler is constant, theoretically, the smaller the particle size of the filler, the better the surface properties and mechanical properties of the coating film. If the particle size of the filler is reduced to a level similar to the particle size of titanium dioxide (0.2~0.5μm), the polycarbonated titanium produced in the formula can be isolated, more effective dispersion centers can be formed, and the hiding power of titanium dioxide can be improved, which is the spatial separation principle of the fine filler. Similarly, micro-refinement fillers can also reduce the amount of pigment used. 3. Nanotechnology of powder filler The most commonly used nanomaterials are nano-silica, nano-titanium dioxide, and nano-calcium carbonate. It is reported that nano titanium dioxide has transparency, can improve the mechanical properties and ultraviolet absorption of coatings, and can be used in automotive overlay varnishes, which can significantly improve the weather resistance of powder coatings. Because nanomaterials are very fine particles, the surface activity is quite high, and it is easy to agglomerate and flocculate, so the surface treatment of nano fillers, the selection of adding methods and dispersion equipment, the amount of nanomaterials added in powder coatings, and how to disperse into the base resin are the key to the application of nanomaterials in powder coatings. In the design of powder coating formulation, different fillers can be selected according to the product performance requirements to achieve the best results. 4. Functionalization of powder coating filler The development direction of functionalized powder coating is to improve the physical, chemical and mechanical properties of some aspects of powder coating, or to give powder coating a new function. For example, kaolin and wollastonite powder powder are used in the production of electrically insulating powder coatings, which can not only reduce the cost of powder coatings, but also improve electrical insulation. Aluminum hydroxide and magnesium hydroxide have flame retardant effects, which can be made into flame retardant powder coatings, and can also control rheology, improve adhesion, control gloss, improve hiding power, etc. Therefore, the fillers for powder coating should shift from simple cost reduction to other functional research, and develop more new fillers with excellent performance and low price to meet the needs of the continuous development of powder coatings.   Powder coating is an energy-saving, resource-saving, low-pollution environmentally friendly coating. Due to the increasing demand for energy in countries around the world, reducing energy consumption and protecting the environment have become the main development directions. Therefore, the development of powder coatings that can be cured at low temperatures, have high weather resistance, are highly decorative and can be applied thinly will be the main development direction in the future. Driven by the demand for powder coatings, the demand for powder fillers such as calcium carbonate, quartz, mica powder, talc, and kaolin will inevitably increase. And the requirements for the fineness, functionalization, and surface modification of powder fillers are getting higher and higher.

The super equipment of the "infrastructure madness", There must be wanton power, but also anti-manufacturing paint.     Behind the reputation of "infrastructure madness", there is an indispensable main force - construction machinery. As the super equipment of the "infrastructure madness", construction machinery is facing the challenges of extreme working environment while bearing a huge workload, and in the face of various unfavorable factors, it is necessary to have wanton power and anti-manufacturing coating.     In practical application, due to the differences in local climate, construction machinery has been exposed to different temperatures and humidity in the outdoor environment for a long time, wind and sun, rain and snow, and various chemical corrosion that may be faced in the construction process, which will cause wear and tear on the coating of construction machinery, shorten its service life, and even cause safety accidents.       The weathering resistance and anti-corrosion of ordinary construction machinery coatings are difficult to meet the needs for a long time, so the market has put forward higher expectations for the coating protection of construction machinery.     WANAN Group has a testing center that has obtained CNAS authoritative certification, and its product testing capabilities have reached the national leading level. After testing, the impact resistance, damp heat resistance, salt spray resistance, acid and alkali resistance and aging resistance of WANAN construction machinery powder coating performance is stable, and the coating is not foaming, not pulverizing, wrinkling and not falling off in the face of sediment erosion, acid and alkali corrosion and other working environments for a long time, providing long-term protection for construction machinery and effectively extending the service life of the product.     Due to the complex shape, size and sharp corners of construction machinery components, the requirements for coating performance and coating process are higher and more complex.       Compared with traditional coatings, WANAN Construction Machinery powder coatings can achieve one-time spraying molding, with a high degree of automation, fast curing speed, saving the amount of paint and spraying coatings to achieve a recycling rate of more than 99%. Improve the coating efficiency, make the construction machinery products achieve better corner coverage, and continue to provide environmental protection coating solutions for the construction machinery industry to reduce costs and increase efficiency.       According to the different needs of customers for the painted surface, WANAN Group can tailor construction machinery powder coatings with rich colors, gloss and texture, which are widely used in cabs, hoods, ladders, benches and other construction machinery parts; Excellent yellowing resistance, gloss retention and color retention performance can ensure the durability and beauty of construction machinery coating products.       While realizing the high performance of the coating, it restores and cures the beauty of color, meets the diversified aesthetic needs of the market with excellent visual expression, and provides more possibilities for the appearance design of construction machinery and equipment.

Powder coating is a solid powder coating composed of solid resin, pigment, filler and additives, etc., which is mostly used for anti-corrosion construction. Compared with ordinary solvent-based coatings and water-based coatings, the dispersion medium of solvent-based coatings is different, the dispersion medium of solvent-based coatings is organic solvent, the dispersion medium of water-based coatings is water, and the dispersion medium of powder coatings is air. Since powder coatings basically do not contain organic solvents, they are environmentally friendly coatings, and they have been vigorously promoted in the field of environmental protection. In addition to the characteristics of environmental protection, powder coatings also have the advantages of reusability and high comprehensive utilization. The principle of electrostatic spraying is to use the high-voltage electrostatic corona electric field to connect the high-voltage negative electrode on the metal deflector mark at the head of the spray gun, and the sprayed workpiece is grounded to form a positive electrode, so that a strong electrostatic electric field is formed between the spray gun and the workpiece. When the powder coating is sent from the powder supply barrel to the deflector rod of the spray gun through the powder pipe as the compressed air used as the carrying gas, due to the corona discharge generated by the high-voltage negative electrode connected to the deflector rod, a dense negative charge is generated near it, so that the powder is negatively charged and enters the electrostatic field with high electric field strength. Under the dual action of electrostatic force and carrier gas, the powder evenly flies to the surface of the grounded workpiece to form a uniform powder layer, which is then heated and solidified into a durable coating film. Good powder coating is very easy to spray, spraying 1-3 guns can cover the substrate, less secondary recovery powder, high work efficiency. Poor powder coating is not easy to powder, spray 3-5 guns to cover the substrate, secondary recovery powder is more, and the work efficiency is low. By recycling and then constructing, the comprehensive utilization rate of good powder coating can reach 99%. For powder coating, we must not ignore the importance of the first-time powder rate. The powder coating rate generally refers to the powder coating coverage, under the premise of ensuring the appearance and mechanical properties of the powder coating film, the amount of powder coating consumed per unit profile, that is, the production cost. Therefore, the powder loading rate of powder coating is a very important factor, and it is a technical index determined by a variety of factors. So how can you improve the powder coating rate?   1. Control the particle size distribution of powder coating, the narrower the better   Because the particle size of the powder coating is related to the charge charge, the larger the particle size, the greater the charge charge, if the particle size distribution of the powder coating is uneven, there will be a large particle size to reach the surface of the sprayed object first, and the small particle size will arrive or can not arrive, so that the powder rate is reduced at one time, and it is easy to appear the appearance quality problem of the paint film. Therefore, it is necessary to control the particle size of the powder coating within a certain range, not too big nor too small, each enterprise will formulate its own standards according to the needs of downstream customers, and the general particle size is about 40-50μm.   2. Increase the resin content   Among the components of powder coatings, resin, as a polymer compound, has the highest dielectric constant, and pigments, fillers and other dielectric constants are low. If there are more substances in the powder coating with a higher dielectric constant, the powder rate will be increased when spraying, but it will also increase the cost, and the coating company needs to configure the resin content according to customer needs.   3. Reasonable choice Pigment and filler fineness and dispersion have a lot to do with powder loading. Pigments and fillers with uniform fineness and good dispersion can improve the primary powder rate.   4. Indispensable conductive additives   Conductive additives can make powder particles carry more charge, so it is necessary to pay attention to the addition of conductive additives in the formulation design. Especially for parts such as groove dead corners, due to the weak power line of the Faraday effect, the powder particles with more charge can reach the surface of the workpiece by their own force, thus improving the powder loading rate of these parts.   5. Spraying process conditions   Due to the difference between the climate between the north and the south, and the different temperature and humidity characteristics in winter and summer, it will affect the powder rate to some extent, so it is necessary to design a relatively stable temperature and humidity, a relatively clean spraying environment, a relatively stable voltage, a more appropriate spraying spacing, a suitable air pressure, and a good grounding of the workpiece.   6. Suitable spray gun   The primary powder rate is related to the type of spray gun, the process parameters, the shape of the workpiece, and the spraying method. Many companies only pay attention to the maximum powder output of the spray gun, in fact, the compressed air output and air pressure increase, the powder output can be increased. However, it is a question whether the high-voltage electrostatic generator can charge so much powder. In the case of spray guns, dense powders block each other's path to charging, leaving the powder behind uncharged, or charged, with very little charge. From the point of view of the spraying process, when the coating surface reaches electrostatic equilibrium, the powder particles that come behind and the particles on the coating surface will repel each other, and even fall against the opposite movement of ionization, and be recovered by the recovery equipment. Therefore, the amount of powder output should be measured according to the charged capacity of the spray gun, and whether the powder is fully charged should be considered, and according to the shape of the sprayed workpiece, according to repeated experiments. In addition, if the workpiece has grooves, grooves, sharp corners, small holes and other shapes, it will produce Faraday shielding phenomenon, and the sprayed coating will be very thin and leak the bottom.

What is a green coating?     Environmental protection coating It refers to the coating products whose performance indicators and safety indicators meet the respective product standards and meet the technical requirements of national environmental labeling products.     The so-called green environmental protection coating refers to the human body and the living environment with non-toxic, harmless, heat insulation, flame retardant, anti-ultraviolet, anti-radiation, insect-proof, anti-poison and other special functions, its hardness, finish, moisture-proof, breathable, frost-resistant, rub-resistant, moisture-resistant, corrosion-resistant and strong adhesion and other properties are very obvious, and its service life is more than five years longer than traditional coatings. It is especially harmless to human health, and is especially suitable for a high-performance coating for the exterior walls of buildings that are picky about climate, moderation and sunshine. Green paint is not absolutely free of harmful substances, but to minimize the harm to human health, just to say that it is low pollution rather than no pollution. The harmful substances in the coating basically come from additives, generally speaking, the raw materials of the coating are not toxic, but the product must add some volatile agents, solvents, etc. These additives contain volatile harmful substances. Eco-friendly coatings can also reduce exhaust emissions and radioactive pollution, reduce energy consumption, and improve the reuse rate of resources.     Harmful organic volatiles and heavy metal salts and other components must not be added to green paints, and must be odorless, non-toxic and pollution-free through professional demonstration. When the construction is painted, it is simple, time-saving, trouble-free, the plane is smooth and smooth, and the decorative effect is beautiful and generous. Green coatings are in short supply in China's market and have been vigorously promoted.     People's awareness of environmental protection is increasing, and the quality of paint products is getting higher and higher, therefore, unenvironmentally friendly, unsafe coating products will be spurned by consumers, and the coatings that meet the needs of people will be green, environmentally friendly, and can replace the traditional solvent-based coatings with serious pollution, which is conducive to enhancing people's health and improving people's living environment. It is also important for the home environment to be safe, environmentally friendly and promote the sustainable development of society.   Market Overview According to data from market research institutions, the global green paint market will reach 546.109 billion yuan (RMB) in 2022, and the global green paint market is expected to reach 809.934 billion yuan by 2028, with a compound annual growth rate of 6.74% during the forecast period. According to the research of internationally renowned institutions, in the past two decades, environmentally friendly coatings have achieved a very stable growth rate in Asian countries. As a major coatings country in the Asia-Pacific region, the Indian paints and coatings market has great potential, with turnover likely to increase from $8 billion to $12 billion per annum in the coming years, with India's eco-friendly coatings market being one of the fastest-growing segments of the entire paints and coatings industry. In China, the market size of environmentally friendly coatings has reached 26.663 billion yuan in 2019, a year-on-year increase of 20.3%. It is estimated that by 2025, the market size will reach 37.943 billion yuan, with a compound annual growth rate of 5.3%. Among them, architectural coatings and automotive coatings are the two main areas of the market, and architectural coatings have the largest demand for environmental protection, accounting for about 40% of the total market. In recent years, the competition in China's environmental protection coating industry has been fierce, mainly by international brands to occupy the vast majority of the market share, but local companies are also trying to challenge. Although the entry threshold of the environmental protection coating industry is not high, small enterprises can also enter the market competition, but due to the small scale and limited technical level, it is difficult to break through the monopoly position of foreign brands at this stage.   Categories and properties of green paints Experts at home and abroad mainly focus on the following aspects in the research and development of green products: water-based coatings, powder coatings, high-solid powder coatings, and have achieved good results. Powder coating Powder coating is 100% solid powder coating, which is a coating in powder form. The biggest difference between it and general solvent-based and water-based coatings is that they use different raw material components, which are absolutely combined with green and environmentally friendly water as dispersion medium or solvent. During the coating process, the part of the paint that spills out is not wasted, it can be recycled and reused, and there is no solvent volatilization, so production and construction are safe. It is easy to realize automatic paint canning, and the efficient productivity has been further improved, which is in line with the internationally popular "four E" principles of environmental protection, economy, high efficiency and excellent performance, and the varieties of such coatings have developed rapidly.  Thermoplastic and thermoset belong to the two types of powder coatings. The first is thermoplastic powder coatings, which are more expensive because they contain thermoplastic resins with high molecular weight as film-forming substances, most of which are used for functional coatings, which are chemically resistant and tough. The second is thermosetting powder coatings, and the synthesis of thermosetting resins and curing agents is the main component of film-forming substances. Because the molecular weight of thermosetting resin and curing agent is lower than that of thermoplastic resin, the fluidity of low molecular weight is relatively stable when curing, the wettability of its surface is also relatively good, the adhesion to the substrate is very strong, and the appearance of the coating film is also relatively beautiful. We usually see powder coatings such as epoxy, polyester, polyurethane, etc., which are thermosetting resins. At present, in the chemical industry, the production and application of thermosetting powder coatings are large-scale and the market share is relatively high. Water-based paints Water-based coatings with water as thinners are non-toxic and non-irritating, water-based coatings will not be easy to turn yellow, and green environmental protection coatings are harmless to human health and do not pollute the environment. In addition, water-based paints are non-flammable, unlike oil-based paints, which need to be stored separately, and it is convenient to store. At present, there are three main categories of water-based coatings on the market: First, water-soluble paints, also known as "water-based paints". The main components of this type of water-based paint include water-soluble resins and other resin-based raw materials. It is super soluble, and the resin material forms a strong coating to protect the wall immediately after being applied to the surface. The water-based paint that has come out has strong environmental performance, so it can be called the "third paint revolution" by the chemical industry. Second, water-dilution coatings. It mainly adds emulsion emulsion to the paint to dissolve the resin, and directly adds water to dilute the paint and then paint the wall during construction to achieve satisfactory results. According to the analysis of the current situation of the change process of the global coating industry, it can be seen that the mandatory use of water-based paint in Europe and the United States has entered the agenda, and China's pace towards water-based paint will also be fully developed, and the development direction of paint in the future will be water-based paint to occupy a dominant position. Third, it is the latex paint used by most families at present, also called "water-dispersible paint". The main principle is to form emulsions mainly from synthetic resins. High solids coatings Solvent-based coatings commonly referred to as VOCs in the chemical market actually refer to solvent-based coatings with high solids content. Compared with the volume of traditional solvent-based thermosetting coatings, the solid content is usually about 75%~85% higher, and it is even higher than that of thermoplastic coatings. So far, many countries in the world have not made a unified definition of high-solids coatings, which in China refers to their solids content greater than or equal to 75%. Internationally, the base color paint of automobile topcoat or flash metallic paint refers to the high solids of high-solids coatings must be about 45NVV, and for high-pigment primers, the high solids of its primer must reach more than 50NVV. How can such a requirement be met? First of all, it is required to reduce the molecular weight of the synthetic resin of the coating and the average functionality of each molecule; Second, the molecular weight distribution must be narrowed. In this case, there are some difficulties in maintaining the function of the coating film at the same time. In addition, this kind of coating also reduces a certain amount of organic solvents, to a large extent, saves the solvent in the production and use of the coating, reduces pollution, but does not reduce the construction and film-forming performance of the coating. The first generation of high-solids coatings failed to meet the requirements of high solids in terms of hardness and color retention, while the latest generation of high-solids coatings developed with low solvent content and high quality standards have been widely used in many industries to escort green environmental protection. With the increasing awareness of environmental protection and the continuous promotion of environmental protection policies, the prospects of the environmentally friendly coating market will become more and more broad. While it is growing rapidly, this field is also facing unknown challenges. Enterprises need to continuously improve their technical level and enhance their comprehensive strength in order to be invincible in the ever-changing market environment and better cope with future challenges and opportunities.