News

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

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

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

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

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

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

introductionThe coating industry has a very long history in the development of the national economy and infrastructure, which provides a basic guarantee for the development of various undertakings in China. However, with the gradual increase of the country's attention to environmental pollution, traditional solvent-based coatings have been unable to meet the development goal of "environment-friendly society", and the development of environmentally friendly coatings is imminent. Due to the current high R&D cost and production cost of environmentally friendly coatings, it has encountered obstacles in the market, and the R&D and production of low-priced, high-performance environmentally friendly coatings to replace traditional solvent-based coatings has become a problem that large coating companies must face. 1 Research significance of environmentally friendly coatings With the rapid development of industrial society, large-scale industrial construction has brought huge economic benefits to people. However, as the problem of environmental pollution becomes more and more serious, environmental protection has become the most basic task of all countries. White pollution, water pollution, air pollution, light pollution, and indiscriminate felling of trees and many other pollution problems closely related to human life can no longer be ignored. However, in the face of fierce competition in the market economy, interests and the environment have become two opposing factors, and some enterprises are facing huge profit temptations in exchange for economic benefits at the cost of polluting the environment. In today's world, the environmentally friendly coating industry is still in an emerging stage of development, and countries around the world are actively developing new environmentally friendly coating products. Because solvent-based coating products have greater pollution in the production process, and at the same time produce greater harm to the health of workers, and volatilize a large number of toxic gases in the process of use, which also has a huge harm to the health of users. The latest R&D achievements of various countries have initially solved serious problems such as high pollution and high toxicity, but due to the high production cost and insufficient purchasing power of the purchasing group, environmentally friendly coating products were once in the unsalable stage. Therefore, the development and production of cheap and environmentally friendly coatings has become a higher goal for the innovative research and development of coating enterprises. Because of this, the development of environmentally friendly materials and the replacement of existing materials with high pollution or production of highly polluting materials have become a focus of today's society. The successful development of environmentally friendly materials not only brings greater economic benefits to the society, but also solves the contradictory relationship between the economic benefits of high-polluting enterprises and environmental protection, and at the same time makes the best solution to the problem of environmental pollution. This paper takes the development of environmentally friendly coatings as the research object and discusses the future development of China's environmental protection coatings. 2 Research and development status of environmentally friendly coatings At present, China's environmentally friendly coatings are in a stage of rapid development, and the commercially available environmentally friendly coatings mainly include: water-based coatings, powder coatings, solvent-free coatings, high-solid coatings, light-curing coatings, etc.

preface Powder coating is a new type of solvent-free 100% solid powder coating. It has the characteristics of solvent-free, pollution-free, recyclable, environmental protection, energy and resource saving, labor intensity reduction and high mechanical strength of coating film, and is one of the fastest growing environmentally friendly coating varieties.   At present, the main domestic powder coating market is mainly low-to-mid-range, and the share of polyurethane powder coatings and acrylic powder coatings with good weather resistance and decorative properties is relatively low, and the development space is relatively large.   Most powder coatings, on the other hand, are thermoset and require the use of a hardener. The matching of hardener and resin is crucial for various properties such as storage stability, curing speed and application leveling performance, film appearance, and film mechanics and weather resistance. This time, the editor here is a review of the main curing agent varieties used in powder coatings. 1. Shrinkage dry grease curing agent Glycidyl ester curing agents have epoxy groups and are mainly used with carboxyl polyester resins. The most important of these hardeners is triglycidyl isocyanurate (TGIC).   TGIC has three epoxy groups that make it highly active and crosslinked, and the stable triazine ring gives the coating good heat and weather resistance   TGIC cured polyester powder coatings are widely used due to their adjustable curing properties, good mechanical and weather resistance.   However, due to a certain irritation and suspected carcinogenicity, it is gradually banned by the European Union, while the US market is still in use, so for a long time, there will also be a certain market.   In order to avoid some of the shortcomings of TGIC, various companies have also introduced some structurally modified glycidyl ester curing agents.   Among them, the mixture of triglycidyl trimellitate and diglycidyl terephthalate is a curing agent developed by Huntsman, and the trade name is PT910.   Compared with TGIC, PT190 eliminates ecotoxicity, but still has some contact toxicity and severe irritation. In addition, due to its low functional group content, the reactivity is reduced, and an accelerator needs to be added when it is used.   Tri-β β-methylglycidyl isocyanurate is an alternative to TGIC manufactured by Nissan under the grade MT239. Nissan considers it to be much less toxic than TGIC. Due to the presence of methyl groups at the β position, its reactivity is lower than that of TGIC.   In addition, glycidyl methacrylate polymers are also used as powder coating curing agents, which can be used as a substitute for TGIC in some fields. 2. Hydroxyalkyl amide curing agent At present, hydroxyl alkyl amide (HAA) is gradually replacing TGIC as the first major type of curing agent for weather-resistant powder coatings, and its main varieties are Primid XL552 and Primid QM1260 (see Figure 1). The curing basis of HAA is to use the hydroxyalkyl group at the β position and the carboxyl group on the resin to carry out esterification and dehydration reaction. Its esterification reaction activity is highly high and does not require the addition of catalysts. From a toxicological point of view, both HAA-based hardeners are completely safe.   The only difference in the molecular structure of QM1260 compared with XL552 is that there is an extra methyl group on the carbon atom where the hydroxyl group is located, and the presence of steric hindrance effect may slightly reduce the reactivity of the hydroxyl group, but it can play a certain shielding role in the ester group formed after curing, thereby improving its hydrolysis stability and inhibiting the yellowing of the paint film.   The biggest disadvantage of powder coatings prepared with HAA as curing agent is that water molecules are released during the curing process, which will affect the compactness of the paint film.   In the case of thick coatings, pinholes and blistering may occur. To overcome these problems, it is necessary to slow down the curing rate of the coating so that the coating remains longer at low melt viscosity, allowing time for water molecules to escape. 3. Isocyanate curing agent As a kind of powder coating, polyurethane powder coating has many excellent properties, such as high gloss, excellent decorative performance, strong wear resistance, good adhesion, and good weather resistance, anti-corrosion, electrical properties and mechanical properties;   It can be said that it takes into account the advantages of epoxy and acrylic powder coatings, and has the advantages of non-toxicity compared to pure polyester powder coatings.   The powder coating can be used in many applications, including industry, agriculture, transportation, and aerospace.   The use of isocyanate curing agent to cure hydroxyl polyester resin is an important variety of powder coatings.   However, the activity of the isocyanate group is very high, and the isocyanate group needs to be sealed with a sealant BH (as shown in Figure 2) in the preparation process of powder coating, and then unsealed during cross-linking curing. A trimer of IPDI (isophorone diisocyanate) is common (Figure 3). The biggest disadvantage of polyurethane powder coating is that when it cures into a film in the oven, it releases a sealant, causing pollution to the ambient atmosphere.   In addition, when the coating film is too thick, pinholes or bubbles are prone to occur due to the release of the sealant. To this end, it is necessary to minimize the amount of sealant and reduce the emission to the atmosphere, while considering the use of non-toxic sealants.     In order to reduce the amount of sealant, the self-shrinkage of IPDI can also be used to form a ureadione structure, which can decompose and re-release the isocyanate group at a certain temperature (Figure 4). Diethyl malonate, a β dicarbonyl compound, can block isocyanates (Figure 5) and cure at low temperatures of 120-140 oC, making it a promising low-temperature curing agent for epoxy and its hybrid formulations. The isocyanate (Fig. 6) enclosed by oxime (generally with butanone oxime) is precipitated during curing, and there is no unpleasant smell and low curing temperature, which is a promising low-temperature curing agent, and is used in polyester with hydroxyl end for polyurethane powder coating, but there is a yellowing problem. 4. Carboxylic acid curing Carboxylic acid curing agents are used for the curing of epoxy resins, epoxy-containing polyester or acrylic resins. Carboxylate polyesters used for curing polyester-epoxy powder coatings also fall into this category, although polyester resins may be the majority of the coatings.   The carboxy-based polyester resin and the epoxy resin are cross-linked and cured with each other, the epoxy resin can reduce the cost, give the paint film corrosion resistance and water resistance, and the polyester resin can improve the flexibility and weather resistance of the paint film.   The synthesis of terminal carboxyl polyester is generally divided into two steps, first synthesizing hydroxyl terminal polyester, and then using trimellitic anhydride to further esterify to obtain terminal carboxyl polyester.   Small molecule anhydrides such as phthalic anhydride and trimellitic anhydride can also be used as curing agents for epoxy resins in the presence of accelerators, but they are rarely used as curing agents for powder coatings due to their strong hygroscopicity and strong irritation to the human body.   A typical representative of small molecule carboxylic acids as powder coating curing agents is dodecanedioic acid (DDDA).   Acrylic powder coatings with it as a curing agent are the most weather-resistant powder coatings and can be used for automotive topcoats. According to reports, the SMART model in Europe uses acrylic powder coating.

The cycle of the four seasons, the 24 solar terms, the 72 phenological changes, and the different solar terms correspond to the unique climate changes, weaving a colorful picture scroll for the world, each with its own characteristics and complementing each other. The Chinese nation is well versed in the way of color. 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 world of WANAN's color aesthetics, the beauty of color is deeply rooted in the natural timing of the shift. The days are short, so it is called "winter solstice". The arrival of the winter solstice means that the year has come to an end, and the beginning and end of the color are also changing. One of the colors of the soft, thick, and dense window screens used in Jiafu in the Dream of Red Mansions is silver-red, and silver-red is described as a whitening color in red that seems to have a silver light. During the winter solstice, the sky is cold and the ground is frozen, the snow is drifting in the north, and the sun shines on the snow, white and red, just like the earth is covered with a layer of soft smoke, giving people an excellent visual experience. WANAN red series powder coatings capture natural colors and are applied in the field of building materials, giving doors and windows a silky visual experience, putting on an elegant coat for doors and windows, making life glow with faint vitality, and realizing the effect of combining function and beauty. Lotus red, the red color of the lotus flower, is pink and bright. The winter solstice occupies a very important position in the 24 solar terms, and the food on this day is also valued. In the north, there is a saying that "if you eat dumplings on the winter solstice, your ears can't be frozen", and people in the south will cook a pot of steaming rice balls on this day, and the lotus-red rice balls mixed with fruit and vegetable juice will taste even sweeter. Wan'an Chi series powder coating is pink and dreamy, and it also brings gorgeous and beautiful color vitality to the indoor and outdoor furniture coating, like glutinous rice balls giving people a warm and harmonious spiritual experience.   "Purple plum" as the name suggests is the color of the plum, plum blossom with its perseverance and beautiful and elegant flower posture, deeply loved by people, for many years and peony together as the "double national flower". In the winter solstice season, the plum blossoms, in terms of visual experience, purple is noble and mysterious, symbolizing the noble and elegant quality of the plum, reminding people to keep their hearts pure and beautiful, even if they are in the corner, they must be lonely and self-appreciative. Symbolizing the beauty and positivity, the WANAN red series powder coating is used in the field of building materials, giving people a sense of elegance visually and transmitting positive energy. Purple ore is the traditional pigment color of Chinese painting, which is taken from the gum secreted by the lac insects, which is purple-red and amber, and the rouge prepared from it is called "cotton rouge". "Tiangong Kaiwu" records: "The ancient method of swallow fat (rouge) is based on purple ore dyeing cotton. "The clouds at the winter solstice are like rouge smeared on the face of a beauty, with a very restrained and subtle beauty. WANAN red series powder coatings take traditional colors, encounter general industrial products, just like beauty makeup, so that ceramics, plastics, glass and other general industrial products glow elegant healing vitality, so that every design of industrial products has become a deep integration of science and aesthetics. The beauty of the color of the winter solstice starts from "silver red", inherits the "lotus red", and turns to "purple plum", which is in line with "purple mine". The flying ice and snow, the warm rice balls, the dark fragrance of the plum, and the clouds on the horizon are all indispensable moving colors in life. With the flow of solar terms, the rise and fall of colors are ever-changing, and a scene is beautiful. WANAN powder coating paints the beauty of solar terms with color, and with the aesthetic concept of "five colors and four seasons", so that every moment of life glows with a unique and charming brilliance.

(WINTER)     In the eyes of children, the snow-covered winter is like a fairy tale kingdom, and every snowflake is like a fairy flying in the air.         The warm and bright room is like a fairy tale castle, providing shelter for children from cold and hunger.     Children's smiles are the most precious treasures, and they deserve our best care. To build a fairytale castle for children, safe and beautiful painting is an indispensable part.     Wanan MDF powder coating, with its non-toxic and non-polluting characteristics, brings lasting charm to children's furniture, so that every parent can rest assured and fill every inch of space with full expectations.     "Dream Castle" is inseparable from colorful and bright colors, which are an important medium for children to perceive the world and have an important impact on children's growth and development.     WANAN MDF powder can provide a wide range of color options, such as bright Wanan Yellow series, Long Wanan Green series, and warm Wanan Red series...... It is applied to children's furniture, painting the dream castle with colorful colors, bringing colorful and bright memories to children's childhood.     In 2021, the MDF powder coating production line of Fujian Mutu Intelligent Furniture Co., Ltd., a subsidiary of WANAN Group, will be put into operation, with selected E0 level environmentally friendly boards, using six-sided integrated spraying process, 360° spraying molding without dead ends, providing a solid guarantee for children to create a safe and healthy growth environment.     The coating of WANAN MDF powder coating has excellent performance such as impact resistance, wear resistance, scratch resistance, etc., and can effectively prevent furniture cracking, deformation, moth-eaten and blistering caused by paint film mildew, external impact, oxidation erosion, etc., and ensure that the coating coating will not appear chalking, peeling and other abnormal phenomena for a long time, prolong the service life of furniture, and contribute to the "Dream Castle".     Children's fragile immune system is easy to be attacked by bacteria and viruses, so the "Dream Castle" must be tasteless, non-toxic, and reassuring, and children can explore freely and boldly inside.     Tested and certified by authoritative institutions, WANAN MDF powder coating products meet the Class I antibacterial standard and Class 0 antifungal standard, with an antibacterial rate of > of 99.99% and an antiviral activity rate of >99.9%.     Childhood is colorful and should be full of laughter, WANAN MDF powder coating paints the background color of the "Dream Castle" with colorful colors, and cares for the growth and development of children with excellent quality.

The background color of the northern winter is white, and the earth after the snow is covered in silver, like a blank space seen by heaven and earth. The world seems to have pressed the mute button, and all the hustle and bustle has fallen silent. The snow is pure and intoxicating, with mountains, houses and trees bathed in snow and ice. Inspired by the winter snow, the WANAN White series of powder coatings infuses the furniture with the purity and delicacy of ice and snow, so that the flawless white creates a comfortable and relaxed living space, and makes life glow with new brilliance in simplicity and tranquility.   In winter, plum blossoms bloom proudly with their bright red color and tenacious vitality, becoming a beautiful landscape in a silvery white, and its fragrance is light and distant, making people intoxicated. The intersection of red plum and white snow creates a unique harmonious beauty that makes people feel the enthusiasm of life in the harsh winter.     The WANAN red series powder coating freezes the sincerity and enthusiasm of red plum with color, and integrates vitality into the field of high-temperature resistant coating such as ovens, so as to achieve the harmony and unity of function and aesthetics. Eating a hot barbecue in winter will add a lot of happiness and anticipation to life.   The south is beautiful in all seasons, and there is no disturbance of ice and snow in winter. Although you can't appreciate the fun of boiling snow and tea, the green mountains and green waters that keep you alive are enough to comfort people. The mountains still maintain the green color, the vegetation is luxuriant, and there is no monotony and solemnity of winter, and the winter in the south is like being in another spring.   The bright and fresh WANAN green series powder coatings are like vibrant winter green mountains, which are used in the field of outdoor furniture coatings, injecting lightness and nature into the busy and noisy urban life, allowing people to find a peaceful place.     The winter sun is warm and warm, and the golden light pours on the snow, and the whole world seems to be shrouded in a golden veil, presenting a dreamlike effect. Under the caress of the warm sun, it seems that all the cold and fatigue are dispelled, making people feel happy and rejuvenated.   Winter sunlight has the power to inspire and is a great expression of the power and beauty of construction machinery. WANAN yellow series powder coating gives construction machinery a bright and warm coating, so that each product is full of vitality and enthusiasm, and you can visually feel the power and beauty of machinery, and realize the unity of visual effect and function.     There are also colorful colors in winter, WANAN always has a sincere heart, with the concept of five colors and four seasons, to explore the color aesthetics in life, so that the color bursts out of strong vitality, so that life can feel the beauty brought by color anytime and anywhere.

    In today's competitive business environment, FUJIAN WANAN INDUSTRY GROUP CO.,LTD has successfully won the Alibaba platform gold pin sincere enterprise certificate with its excellent quality and unremitting efforts, which not only demonstrates the deep strength of FUJIAN WANAN INDUSTRY GROUP CO.,LTD in the field of powder coatings, but also marks a solid and important step in its digital business arena.     As a pioneer national enterprise in the field of thermosetting powder coating in China, FUJIAN WANAN INDUSTRY GROUP CO., LTD has always adhered to the persistent pursuit of quality and continuous investment in innovation since its establishment. Over the years, the production and sales of its products have been in the forefront of the same industry in the country, and it is the first in Fujian Province. The award of the Ali platform Jinpincheng Enterprise Certificate is a high recognition of FUJIAN WANAN INDUSTRY GROUP CO., LTD  long-term adherence to high standards and strict requirements of the company's business philosophy.       Behind this honor is the all-round outstanding performance of FUJIAN WANAN INDUSTRY GROUP CO., LTD. In terms of product research and development, the group has established a powder coating research institute, which has attracted many top technical talents to join, equipped with advanced research and development and testing equipment in the industry, and actively carried out industry-university-research cooperation. Through continuous technical research, FUJIAN WANAN INDUSTRY GROUP CO., LTD has won more than a number of patented technologies and built a strong technical barrier. At the same time, the WANAN testing center has developed rapidly since its establishment, and has obtained the CNAS laboratory accreditation certificate, which further expands the scope of testing and provides a solid and reliable guarantee for product quality. In the field of standard formulation, FUJIAN WANAN INDUSTRY GROUP CO.,LTD also plays an important role as a leading enterprise, leading or participating in the formulation of a number of national, industry, group and enterprise standards, and some standards have won relevant awards, contributing to the standardized development of the entire industry.     FUJIAN WANAN INDUSTRY GROUP CO., LTD has a wide range of powder coatings, covering a wide range of categories, including general type, art type, color type, functional type, chemical system type, etc., which can meet the application needs of many different fields such as building materials, furniture, and construction machinery. Whether it is the decorative protection of building facades or the delicate coating of furniture surfaces, FUJIAN WANAN INDUSTRY GROUP CO.,LTD's powder coatings can provide customers with perfect solutions with their outstanding performance.     After winning the certificate of Jinpincheng Enterprise on the Alibaba platform, FUJIAN WANAN INDUSTRY GROUP CO.,LTD will take advantage of the strong influence and resource advantages of this platform to further expand the market territory and enhance the brand awareness and reputation. Driven by the wave of digitalization, FUJIAN WANAN INDUSTRY GROUP CO.,LTD will continue to adhere to the original intention of quality first, continue to innovate and forge ahead, and work together with global customers to create a more brilliant tomorrow for the powder coating industry. Looking forward to the future, FUJIAN WANAN INDUSTRY GROUP CO., LTD powder is expected to shine more brightly in the international market, become an iconic brand in the field of global powder coatings, lead the development trend of the industry, bring more high-quality and high-performance powder coating products to global consumers, and promote the quality upgrading and sustainable development of various application industries.