One, how to construct powder coating
1. To ensure that the coated surface can fully perform and extend the service life of the coating, the surface of the coated material must undergo strict pre-treatment.
2. When spraying, the coated object must be completely grounded to increase the efficiency of powder coating.
3. For substrates with significant surface defects, apply conductive putty powder to ensure a smooth and even coating.
4、After spraying, the coated object must be heated and cured. The curing conditions should be based on the technical specifications of the powder product, but it is essential to ensure that the curing temperature and time are fully met to avoid quality issues caused by incomplete curing.
5、Immediately inspect after spraying.
6、The recycled powder must be screened to remove impurities before being mixed with new powder in a specific ratio.
7. The powder bins, spraying room, and recycling system should be kept free from contamination by other powders of different colors. Therefore, it is essential to thoroughly clean the area after changing colors.
II. Powder Coating Process Flow
1、Corner Coverage: Before spraying, add approximately 0.5-1.0% of viscosity-enhancing agents such as polyethylene wax or poly(vinyl alcohol) succinate, or additives like carbon black to prevent flow, to the coating formulation. This ensures that the inner and outer surfaces of the coated workpiece corners, as well as the surfaces during film formation, are uniformly coated, avoiding unevenness such as shrinkage or bulging. Otherwise, uneven surfaces will result.
2、Powder Clumping: Powder clumping refers to the formation of lumps or nodules on the coated surface after the coating adheres to the substrate. This is primarily caused by uneven dispersion or agglomeration of the coating powder, or by the adhesion of certain powders, such as metal powders, to the spray gun nozzle. The solution involves adding fine, loose aluminum oxide (Al2O3) and/or silicon dioxide (SiO2) powders, as well as incorporating powders such as powder flow aids 445 and anti-stick agents 780, which help improve the flowability of the dry powder and prevent clumping. This prevents the formation of powder clumps.
3、Pore reduction and pit formation.：Sometimes, after applying powder coatings, the surface of the coated object may exhibit convex and concave granular phenomena. Generally, the convex grains are caused by the presence of non-fusible inorganic matter in the raw materials, or by organic matter produced during extrusion. The concave shrinkage holes are often related to the type of resin or external oil stains. If different organic substances are incompatible or cannot be wetted, small shrinkage holes with a diameter less than 1 millimeter and a large number may occur. The difference between these and pinholes is that pinholes are small and irregular, with a large number, while shrinkage holes are regular in shape. The main causes of large shrinkage holes are the failure of the leveling agent and external oil stains.
4、Paint Coverage: Achieving the desired color can be challenging, especially with black, white, and red colors. Achieving smooth gradients and accurate color mixing can be difficult.
A、Produce black powder with excellent carbon black coloring, with pigment addition ranging from 0.5-1%, and optionally, add 0.2% of Phthalo Blue to adjust the color.
B、In the white powder, the amount of titanium white should be increased by up to 25%. For interior use, adding a small amount of lead white can improve coverage. The general white color is typically mixed with ultramarine blue and permanent violet. Permanent violet provides a vibrant contrast. Adding fine-grained wax can improve dispersion and coverage, as well as eliminate air bubbles and pores.
C、The amount of oil absorption in the pigments in the red powder can be large, which can affect the adhesion. In this case, the proportion of resin should be increased. Red base, 2-3% red pigment, requires adding 5% titanium white powder, and sometimes adding about 3% yellow pigment to brighten.
III. important considerations for powder coating application
1、 Due to the 100% solid powder state of the powder coating, not only must the spraying environment be properly protected, but construction personnel must also take appropriate protective measures, including wearing protective clothing, to avoid prolonged skin contact with the coating. If coating powder accidentally comes into contact with the skin, it should be washed with soap and water, and should not be cleaned with other organic solvents.
2. Powder coating requires a very controlled spraying environment. Typically, this should be done in a well-ventilated area. This is because powder coatings are applied using spraying equipment to coat the object surface with powdered material. Furthermore, the spraying conditions require a certain temperature range, typically below 35 degrees Celsius. In addition, the construction environment must be free of open flames and direct sunlight.
3. Powder coatings are in powder form, so when spraying, it is necessary to ensure that the powder does not clump or solidify. This requires checking before spraying to ensure that the coating is stored in a cool, dry environment, and that the storage area is free of water, oil, or other organic solutions to prevent the powder coating from mixing with these substances.
4、After applying the powder coating with spraying equipment, a coating is formed on the sprayed object due to electrostatic action, achieving the spraying effect. Therefore, electrostatic action is crucial, and it is necessary to ensure that the spraying equipment is completely grounded during spraying to eliminate static electricity and prevent static electricity from affecting the spraying process. Additionally, construction personnel must adhere to electrical safety regulations and practice safe construction.