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    Home > Coatings News > Paints and Coatings Market > Electrostatic spraying requirements for powder coatings

    Electrostatic spraying requirements for powder coatings

    • Last Update: 2020-02-21
    • Source: Internet
    • Author: User
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    1、 Thin layer powder coating the coating with thickness less than 35 (or 30) u is generally called thin layer powder coating Compared with the coating with thickness of 50-70u, the thickness of thin layer powder coating is about half lower As a thin layer powder coating, it must have several characteristics First of all, to cover the substrate well under the thickness of 30U, it is necessary to increase the share of coloring pigments (such as titanium white) to obtain good leveling under the condition of thin coating and reduce the ratio of pigment to substrate (in other words, to increase the share of resin in the formula); As a result of the above two points, the filler content in the formula will be greatly reduced and the powder production cost will be greatly increased Secondly, the resin suitable for thin-layer powder coating should have a lower melting viscosity, which can fully wet the substrate and pigments and fillers on the one hand, and have a good leveling property on the other hand; The formula of polyurethane acrylic epoxy powder coating is suitable for its low melting viscosity Considering the situation of our country, it is a feasible development way that acrylic polyurethane resin is difficult to popularize epoxy resin and good curing agent The particle size distribution of powder is also a very important characteristic for thin-layer powder coating If the maximum thickness is 30U, the maximum particle size of powder should be less than 60u (about 260 meshes) Therefore, it is necessary to strengthen grinding to make the powder finer On the other hand, it is easy to produce a higher proportion of ultra-fine powder less than 10u It is known that too much ultra-fine powder will cause a series of problems, such as low powder rate on the spray gun, easy to agglomerate, etc Therefore, it is not easy to achieve ideal particle size distribution The contradiction between viscosity and glass transition temperature of epoxy acrylic resin and polyurethane resin is also a difficult problem to solve Generally speaking, the glass transition temperature with small viscosity is also low; On the one hand, the control of molecular weight distribution should be narrow; On the other hand, the synthetic formula and production process of these resins should also be adjusted so that the performance of these two aspects can be properly taken into account Thin layer powder coating is still in the development stage in China, but it is still a long way to go, but in any case, it is a development direction Although the production cost of thin layer powder coating is high and the price is high, it can save about 15-20% of the powder cost for users 2、 Heavy duty powder coating The powder coating of heavy-duty anti-corrosion type has better anti-corrosion ability Due to the higher anti-corrosion requirements, linear phenolic epoxy resin is selected Linear phenolic epoxy resin is very different from the common bisphenol a series epoxy resin In its molecular structure, linear phenolic resin is used as the main chain, each molecular chain contains more than three epoxy groups, because its molecular has three functional degrees (bisphenol a system Therefore, the crosslinking density of the cured product is high when curing, so its heat resistance, mechanical strength and chemical corrosion resistance are better than those of bisphenol a series epoxy coatings At present, it is mainly used in the coating of oil and gas chemical pipeline in foreign countries, and it can also be used in the coating of metal parts with heavy anti-corrosion requirements in chemical plants  
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