Talking about the Kinds and Properties of Metal Aluminum Powder Coatings
[China Aluminum] With the country's emphasis on environmental protection, as an environmentally friendly, high-efficiency, high-efficiency, and economical powder coating, the output has increased rapidly in recent years, with more and more varieties, and the application field has gradually expanded. In terms of decoration, in addition to the common types of powder coatings with different gloss and flat surfaces, the types and amounts of orange-color, wrinkle, sand grain, pattern, hammer, and metal powder powder coatings are increasing, and they gradually penetrate into solvent-based coating applications. All areas. Among these, metallic aluminum powder coating is a major variety of major decorative powder coatings, including metallic glitter, metal plating, metallic patterns, hammer patterns, and metallic luster textured powder coatings. The characteristics of this powder coating are all containing metal aluminum powder. By changing the aluminum powder specification, coating formulation and manufacturing process, powder coatings with different properties and coating appearance can be obtained. The following describes in detail the type, manufacturing process, formulation composition, factors that affect the appearance of the coating film, application fields, and existing problems. 2 Types of Metal Aluminum Powder Coatings Metal aluminum powder coating is a more important type of powder metal powder coating. The metal aluminum powder coating is divided into metal glitter and metal coating type powder coatings with a film coating appearance according to the appearance of the coating film; the coating film has a texture-like pattern, a hammer grain, and a metal luster texture powder coating. The film-forming materials that can be used for metal aluminum powder coating are epoxy, polyester epoxy, polyester, polyurethane and acrylic resin, and the domestic main products are polyester epoxy powder and polyester resin type aluminum powder coating. (1) Metal flash powder coating is a powder coating made by adding non-leaf type metal flash aluminum powder to the powder coating base powder. After the coating is cured and formed into a film, the metal flash aluminum powder uniformly reflects light to make the coating film. Flash effect. (2) Metal plating powder coating is a powder coating made by adding floating aluminum metal powder to the powder coating base powder. After the coating film is solidified, the metal aluminum powder completely covers the coating film surface to form a similar “plating layer or polished stainless steel. The appearance of the coating. (3) Metal pattern powder coating is powder coating made by adding metal aluminum powder and pattern agent to the powder coating base powder. When the coating film is cured, due to the effect of the pattern agent on the surface tension, the metal aluminum is formed on the coating film appearance. Pink silver pattern. (4) Metal Hammer Powder Powder Coating is a powder coating produced by adding metal aluminum powder and hammer powder agent to the powder coating base powder. After the coating film is cured, a silver hammer pattern is formed. (5) Metal luster texture powder coating is powder coating made by adding aluminum powder and texture agent (sand gravel agent or wrinkle agent) to the powder coating base powder. After the coating film is solidified, due to the role of aluminum powder and texture agent The appearance of a metallic luster textured coating. 3 Metal powder coating manufacturing process The main manufacturing process of aluminum powder powder coatings is similar to that of general powder coatings, including: Premixing of raw materials → melt extrusion mixing → cooling and crushing → fine powders → grading screening → finished products For the manufacturing process of the addition of metal aluminum powder in the premixing process (commonly known as the aluminum powder in-process process), the above process is completely manufactured. For example, hammer grain, pattern, and metal plating powder coating are manufactured by using this method. For the powder coating manufacturing process (commonly known as aluminum powder addition process) that requires dry-mixed addition of metallic aluminum powder, the base powder without metallic aluminum powder is manufactured as a semi-finished product according to the above process, and then metal aluminum powder is added according to the formula, and the mixed material is used. The machine is dry and homogeneously mixed to obtain a product, such as a metallic glitter, a part of a metal plating, a pattern, and a metallic luster texture powder coating, which are manufactured by this method. In the manufacturing process of aluminum powder added to the semi-finished products (aluminum powder addition process), in order to prevent the particle size of the metal aluminum powder from being damaged in the mixing process, the appearance of the coating film is affected, and at the same time, the powder coating is prevented from being aggregated during the mixing process. Generally, low-speed stirring mixers with no destruction capability, little heat generation, and even with a cooling device are used for mixing. Such mixing devices include a V-type mixer, a three-dimensional rotating water cooling mixer, a barrel mixer, and bonding ( Bonding) mixers. In the process of dry mixing of aluminum metal powder, in addition to the state-of-the-art mixer, the metal powder and the base powder of other mixers are present in a separated state. Due to the different density and electrical properties of the metal powder and powder coating particles, when the electrostatic powder coating, the electrostatic properties of the two materials are different, the powder rate is also different, resulting in a difference in the aluminum powder content between the powder coating and the coating film. Also, the content of aluminum powder in the recovered powder is different from that in the original powder, and it is difficult to reuse the recovered powder, which will eventually affect the stability of the appearance quality of the coated product and also increase the coating cost. The use of bonding mixers or other mixing equipment or manufacturing processes that can adhere metallic aluminum powder to the powder coating base powder can make the aluminum powder content in the original powder, coating film and recycled powder coating uniform, and the recycled powder can be reused. , At the same time, it can guarantee the stability of the appearance quality of the coating film. Due to the relatively expensive bonding mixers, the cost of paint production is relatively high, and fewer manufacturers use this type of equipment. 4 Basic Formulations of Metal Powder Coatings and Factors Affecting Film Performance 4.1 Metallic Flash Powder Coatings The powder coating is generally composed of a base powder and an aluminum powder. The main composition of the base powder is the same as that of a common powder coating and consists of a resin, a curing agent, a leveling agent, a degassing agent, a transparent pigment, an aluminum powder, and an aluminum powder special auxiliary agent. Matting agents or matting curing agents, etc., generally do not have hiding power pigments. In some cases, transparent pigments and fillers are properly added for the purposes of color grading and improving film hardness, but the amount of filler is less than that of ordinary powder coatings. If you add more, it will affect the flash effect of aluminum powder and the flatness of the coating film. Aluminum powder is added to dry powder in the powder, the amount of 1% -5% of the total amount of the base powder. According to the requirements of the film appearance flash point size and brightness, choose different particle size and amount of aluminum powder. Generally choose non-floating aluminum powder with a particle size of 15-55μm. When the flash point is large, choose aluminum powder with a large particle size. When the flash point is small, select the aluminum powder with a small particle size; when the brightness of the coating film is high, the amount of aluminum powder is required. More, when the film brightness is low, reduce the amount of aluminum powder. 4.2 Metal Plating Powder Coatings The composition of the powder coating composition is the same as that of the ordinary powder coating, and consists of a resin, a curing agent, a leveling agent, a degassing agent, a pigment, a filler, an aluminum powder, an aluminum powder additive, a matting agent or an extinction curing agent. In the formula, the amount of aluminum powder is 1%-5% of the base powder or the total amount of the formula, and different particle sizes and amounts of aluminum powder are selected according to the appearance of the coating film and the brightness of the metal coating, using a particle size of 2.6-15 μm float Aluminum powder. At present, the main type of aluminum powder used is the dry mixing method plus floating aluminum powder. Although the internally added aluminum powder has been developed, there are many advantages. However, compared with the external aluminum powder, the amount thereof is large, the cost of the coating is high, and it takes a while for the real industrialization to be widely applied. 4.3 Metal pattern powder coating The formula of this powder coating is composed of resin, curing agent, pattern agent, pigment, filler, aluminum powder, matting agent or matting curing agent, and is similar to common pattern metal powder. According to the type of aluminum powder, it can be added either internally or externally. Patterning agents can also be added by internal or external methods. In the case of this formulation, no leveling agent is used, and if it is needed, the amount is small. In the formula, the pattern agent and aluminum powder are important factors affecting the appearance of the coating film. With the increase in the amount of the pattern agent, the pattern becomes smaller, the coating film becomes smoother and the three-dimensional effect becomes worse; with the increase of the amount of aluminum powder, the coating film The metal brightness is enhanced; the particle size of the aluminum powder has an effect on the appearance of the coating film. In the case of the same amount, the smaller the aluminum powder particle size is, the brighter the coating film brightness is. In addition, the melt viscosity of film-forming materials, reactivity, the type and amount of pigments and fillers also have a certain influence on the pattern texture. 4.4 Metal Hammer Powder Coatings This powder coating formulation is composed of resin, curing agent, hammering agent, degassing agent, transparent pigment, a small amount of filler and aluminum powder. The amount of aluminum powder in the formula is 0.8% to 1.5% of the total amount of the formula, and aluminum or aluminum powder with a particle size of less than 20 μm can be used. The amount of hammering agent varies depending on the species. If cellulose acetate butyrate CAB551-0.2 is used, the amount used is 0.1% of the total formulation—0.2%. Considering the effect of pigments and fillers on the sharpness of hammer lines, opaque pigments are not suitable for use, and the amount of filler should not exceed 10% of the total formulation, and the texture of the hammer grain is clearer when no filler is used. The amount of hammering agent used in the formulation is the main factor that determines the texture of the hammer grain. With the increase of the amount of the hammering agent, the texture of the hammer grain becomes smaller and the three-dimensional feeling becomes worse; with the reduction of the amount of the hammering agent, the texture of the hammer grain is reduced. Bigger, more three-dimensional, even exposed. In addition, factors such as melt viscosity, reaction activity, and leveling agent addition of the film forming material also affect the size of the hammer grain texture. 4.5 Metallic Gloss Texture Powder Coatings This powder coating formulation consists of a resin, a curing agent, a pigment, a filler, a texture agent (for example, a wrinkle agent, a sand graining agent), and an aluminum powder. In general, a powdered powder coating is used as a base powder, and a certain amount of metal aluminum powder is dry-blended to give the coating a certain metallic luster. The amount of aluminum powder is determined according to the use, and is generally 1% to 3% of the total amount of the formulation, and more suitable is a floating type aluminum powder having a particle size of 20 μm or less. According to the coating appearance requirements, choose different particle sizes of aluminum powder. 5 Application and Problems of Powder Coatings Metallic aluminum powder coating is a decorative powder coating and is mainly used for the decorative aspects of indoor and outdoor articles and products. Outdoor products include street lamps, lamp posts, metal doors and windows, car wheels, etc.; indoor products include ceilings, lighting, toys, fitness equipment, security doors, building materials, shelves, radiators, electric toys and so on. General polyester, polyurethane powder coatings are used for outdoor and demanding indoor products; epoxy and polyester epoxy powder coatings are used for indoor products. Due to the characteristics of powder coatings, metal aluminum powder coatings will gradually replace some of the solvent-based coatings, and its use has continued to increase. However, powder coatings are not perfect, and the micro-leveling, decorative effect, dispersion and concealment of aluminum powder in the coating are not as good as those of solvent-based coatings, and it is easy to expose a very small amount of aluminum particles to the surface of the coating. When exposed to the air, the surface of the aluminum powder oxidizes and darkens the coating, which ultimately affects the decorative effect of the coating. Film coating varnish can overcome this disadvantage, but this increases material and coating costs, and is economically inferior to coating solvent-based coatings. Due to the limitations of powder coatings, metal aluminum powder coatings cannot currently be used for the coating of high-grade car top paints. They can only be used for coating applications where the decorative requirements are not very high. 6 Conclusion Metal powder powder coating as an important variety of powder coatings, all powder coating thermosetting resin can be formulated with this powder coating, so the variety of coatings, a wide range of applications. If the price of "bonding" equipment used to disperse aluminum powder will decline in the future and gain popularity, then the variety of metal powder used for internal processing will be further developed and the cost will be reduced. Then the quality of various metal aluminum powder coatings will be obtained. With higher prices and lower prices, the application area will be further expanded and the usage will grow faster. The proportion of replacing solvent-based aluminum powder coatings will be even greater. Comparison of the advantages of mini Led Wall Pack Light
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