More than 80% of the exterior decoration parts of motorcycle (Scooter) are ABS plastic products, so the coating quality directly affects the market competitiveness of motorcycles. This paper introduces the pretreatment and coating technology of ABS plastic products, and analyzes and discusses some special requirements for the pretreatment and coating of ABS plastics due to the particularity of ABS plastic materials.
ABS (acrylonitrile, butadiene and styrene terpolymer) is a thermoplastic resin plastic, which has high mechanical strength and good processing performance, but its hardness is low, weather resistance and solvent resistance is poor, which can be improved by secondary processing of plastic surface. Coating is one of the important methods of secondary processing of plastic surface. ABS plastics often have problems such as bad adhesion effect, loss of light and pitting point. The main reasons are: surface tension (less than 100mn/cm), solubility parameters are different from solubility parameters of resin and solvent in coating, and the internal stress produced during forming is easy to produce crack of paint film or reduce coating luster, and electrostatic and dust are easily generated on the surface, which affects coating effect Fruit.
The oil pollution on the plastic surface will greatly reduce the adhesion of the coating, which contains the film remover (stearate, wax, polyvinyl alcohol, etc.), auxiliary (plasticizer, antistatic agent, lubricant, anti-aging agent, anti-combustion agent), and other (lubricating oil, dust), etc.
(1) Manual friction test is a kind of treatment method with high labor intensity, and it is usually used in low yield. There are many disadvantages in manual friction test. Due to artificial reasons, the quality is unstable. The dirty cloth will cause the plastic surface to be polluted again, and the solvent is harmful to the operator and pollutes the environment.
(2) The method can effectively remove the weak interface layer such as oil pollution, film remover and antistatic agent, and make the surface coarsening porous, thus improving the adhesion of the coating. But high temperature operation is not conducive to safety production.
(3) The water solution treatment method is especially suitable for the situation of large production and high production efficiency. This method has the advantages of stable quality, light environmental harm, low cost and easy operation, and is gradually replacing the two methods.
Pre degreasing → degreasing → primary water washing → secondary water washing → deionization water washing → activation → blowing drying → water drying (70-75 ℃, 15min)
The pretreatment of ABS plastic products can be produced in line. All processes are spray treated and transported by hanging chain. The equipment adopts the structure of sealed dust chamber.
Generally, the water degreaser containing surfactant is used for spray cleaning, the time is 2-3min, the injection pressure is 20-30psi, and the temperature is 45-55 ℃. Degreasing formula contains phosphate, silicate, surfactant, inorganic minerals, etc. When degreasing agent is used repeatedly, impurities and dirt in the tank liquid accumulate, which will cause the re attachment of the plastic surface dirt, which will affect the coating quality. Therefore, the management of filtration and renewal of the tank liquid should be strengthened. The degreasing effect of water degreaser is good and the quality is stable, but the wastewater discharged by the agent contains phosphorus. At the same time, it is an etching product. Glass fiber reinforced plastic must be lined in the tank and equipment of low carbon steel to prolong the service life of the equipment. In view of the above two points, it is suggested to adopt stainless steel structure equipment and tank body to increase the service life of the equipment. Before discharge, the wastewater can be discharged after it is treated to the standard.
Activation is a process of water meter apintejinustment containing water macromolecules. It can be sprayed at room temperature for 1min and injection pressure of 7-14psi.
The activation can help to remove hard water, convert the hydrophobic plastic surface into the surface containing hydrophilic base, and form a uniform film on the plastic surface, with a thickness of no more than 5nm, but it improves the wettability and adhesion of the coating to the plastic surface. After activation, it should be dried with clean compressed air and dried at 70-75 ℃ for 15min.
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Link to this article：Discussion on surface pretreatment and coating process of ABS plastic products
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