The principle of dipping powder dipping


The principle of dipping powder dipping

Dipping powder impregnation originated from the fluidized bed method, which was applied to the differentiation of petroleum contacts in the Winkleves outburst furnace, and later developed into a solid-gas two-phase contact process, which was gradually applied to metal-plastic coatings. Therefore, it is still sometimes called "fluidized bed coating". The practical process is to put the powder coating into the porous container (movable tank) at the bottom, and feed the compressed air from below through the blower to make the powder coating turn to a "fluidized state". It becomes a fine, evenly distributed powder.


On the basis of the fixed bed, the flow rate (W) is continuously increased, while the loose bed starts to expand, the bed height starts to increase, and each powder particle floats, so the movement from the original azimuth to the magnitude has now entered the flow Bed stage. In the BC section, the powder layer in the fluidized bed expands. With the increase of gas velocity, the powder layer height (I) increases, but the bed pressure (ΔP) does not increase. Change the flow rate within a certain range without affecting the unit power required by the fluid. This is the property of a fluidized bed, and it is this property that is used to carry out the coating process. The uniformity of powder fluidization in the fluidized bed is the key to ensuring uniform coating of the guardrail. The fluidized bed used for powder coating belongs to "vertical fluidization", and the number of fluidization must be determined by experiment. Generally it can be applied. The powder suspension rate in the fluidized bed can reach 30 to 50%.

The technological process of dipping powder is: preheating the guardrail to the melting point of the powder coating by degreasing, immersing the plastic powder into the fluidized bed and adhering it uniformly, and then plasticizing the polymer cross-linked flattened steel-plastic composite product. Thermoplastic dipping powder coating has the characteristics of thermal softening, cooling and then solidifying into a film. First, it is a process of physical melting and plastic film formation. Most of the impregnation process uses thermoplastic powder, typically polyethylene, polyvinyl chloride and polytetrachloroethylene, which are suitable for non-toxic coatings and general decoration, anti-corrosion and wear-resistant coatings.

The principle of the plastic spraying process for the dipping powder guardrail: electrostatic powder spraying equipment (electrostatic sprayer) sprays the powder coating on the surface of the workpiece. Under the action of static electricity, the powder will be evenly adsorbed on the surface of the guardrail to form a powder coating; the powder coating passes through High temperature baking and leveling curing to make coatings with different functions (different varieties of powder coatings); the spraying effect is superior to the coating process in terms of mechanical strength, adhesion, corrosion resistance, aging resistance, etc., and the cost is also equivalent to the coating. Down. Spray powder mainly includes acrylic powder, polyester powder and other types; the quality of spray products is better than that of dip products, and the weight is heavier, but the surface of the product is very good and smooth. The cost of impregnating plastic is relatively low, because the price of impregnating powder is lower than that of iron, and it has the characteristics of rust resistance, acid and alkali resistance, moisture resistance, insulation, aging resistance, good hand feel, environmental protection, and long life. Updated surface treatment process for zinc coating products. The thickness of immersion plating is greater than that of spraying, and the general spraying thickness is only about 0.2mm. Thickness of 3mm and above is dipping.

Key words:

nylon powder,Dip powder

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