What should we pay attention to when painting the surface of plastic shell? I believe many friends are not very clear, because the surface of plastic shell has a special structure. Although the surface of plastic parts has been modified by surface pretreatment, the weak interface layer has been removed, the surface of plastic parts has been activated, and the adhesion of film has been increased, the selection of coating, painting process and painting environment will also be improved when making plastic shell The coating quality is affected. Now, Shenzhen Hongfa Shunda Plastic Shell Co., Ltd. will give you a detailed analysis
The selection of coatings should follow the "similar compatibility criterion" to ensure the excellent miscibility of ABS with coating resin and solvent, so as to form a very thin miscible layer between the coating film and the plastic surface and enhance the adhesion. The solubility parameter of ABS plastic surface is about 9.6; motorcycle is a field product, which should have good decorative properties,
It is also necessary to satisfy the physical and chemical function requirements of the paint film; the thermal deformation temperature of ABS products is 75-107 ℃, and can not be baked at high temperature, so it is necessary to select white dry or low temperature dry coatings when selecting coatings, and the selection scale is relatively narrow. At present, most of ABS plastic parts of motorcycle profession are coated with acrylic acid or polychlorinated ester coatings
The solubility parameters of chloroester and acrylic acid are about 10.0 and 9.4 respectively. Obviously, the solubility parameters and surface tension of these two coating systems are well matched with ABS substrate, and they have excellent wettability and adhesion on ABS substrate. In order to obtain high quality protective coating, the two-component polyurethane primer should be sprayed for 2-3 times, after leveling for 5 rain, the two-component polyurethane varnish should be sprayed by wet touch.
Now, most of the ABS plastic shell coating uses the technical air spraying process, with high labor intensity and poor working environment. The coating power is only about 20% ～ 30%. The coating loss is large and the cost is high. The artificially formed unstable quality factors directly affect the product quality. With the development of science and technology, automatic spraying is gradually applied
For example, the side sprayer is widely used in motorcycle coating, but the side sprayer can not spray according to the shape of the workpiece, while the shape of motorcycle plastic parts is disordered and there are many kinds, which can not meet the spraying requirements. In order to overcome the above defects, foreign enterprises and domestic mainstream enterprises choose robot with spray gun or rotary cup electrostatic spraying on the newly planned plastic parts coating line. Before coating, ionized air is used to remove static electricity, and then alcohol solvent is used to conduct conductive treatment on the surface of plastic parts, so as to reduce the surface resistance, and then conductive paint and varnish are sprayed by robot. The coating power of this electrostatic spraying can reach about 90%, which greatly reduces the production cost, improves the production power, and ensures the product quality. However, the investment and operation cost of robot spraying equipment are low The resistance and viscosity of the coating should be strictly controlled. Generally, the best scale of the resistance value of the coating is 35m ~ 45m (2), and the viscosity of the coating is 2S lower than that of air spraying. In terms of equipment, it is also carried out from the hanging conveying line to the ground chain line, and the ground chain line can reduce the particles and pits on the surface of the workpiece.
Shenzhen Hongfa Shunda Plastic shell company has been specialized in producing plastic shell, CNC hardware processing, CNC plastic processing manufacturers for 15 years, and CNC plastic machining manufacturers providing plastic lithium battery shell, plastic waterproof box, waterproof junction box, plastic shell, outdoor protection box.
