Automotive trims have the function of decorating and beautifying cars, and the quality of their decorative effects directly affects the interior and exterior image of the car. Automotive trims are made of a variety of materials: from customized metal blanks to sheet molding compounds (SMC) composites and glass fiber reinforced plastics (GFRP) to composite plastics (PP, ABS, etc.), these raw materials have very different surface properties. However, the surface energy of these materials is relatively low, so before using structural adhesives, the surface needs to be properly treated to remove surface dirt, dust, oil, grease, moisture, release agents and plasticizers, etc. At the same time, the surface energy of the substrate is increased to be higher than the surface energy of the structural adhesive, so as to ensure that the structural adhesive can fully wet the substrate surface, which is crucial to achieve a strong, reliable and durable bond.

Plasma cleaning of automotive interior and exterior plastics Purpose: coating, spraying, foaming, bonding, etc. after material surface activation

Plasma cleaning uses a plasma generator to generate a set of high-frequency voltages that are connected to the metal car in the sealed chamber through electrodes. The gas near the metal car is ionized into a plasma state by the high-frequency electric field formed between the electrode and the metal car. The gas in the plasma state reacts chemically and physically with the surface of the automotive interior and exterior plastics on the metal car, so that the impurities on the plastic surface are converted into gaseous substances and extracted by the vacuum pump to achieve the purpose of cleaning the material surface.

On the one hand, plasma cleaning can remove hydrocarbon dirt (such as grease and auxiliary additives in plastic materials) on the surface of plastic parts. On the other hand, the high-energy particles in the plasma change the molecular chain structure on the surface of plastic parts, generating free radicals such as hydroxyl and carboxyl that are conducive to adhesion, thereby improving the adhesion of the plastic matrix surface and achieving the purpose of improving the surface activity of the plastic.

For example, modified polypropylene (PP) materials for automobiles are made by adding modifiers such as toughening agents to PP materials to improve the impact toughness and low temperature resistance of the materials. The products are non-polar materials, chemically inert, and not easy to react with other chemical groups. After the surface is glued or painted, the PP substrate is prone to problems such as loose coating glue, shrinkage holes or non-wetting after painting. Therefore, plasma cleaning of modified PP can increase its surface polarity and improve its wetting properties to adhesives and paints.

The flame treatment methods commonly used in the automotive industry currently have problems such as low efficiency, environmental pollution, and poor safety, which do not conform to China's green and environmentally friendly industrial concept. Plasma cleaning technology can improve the physical and chemical properties of the material surface without affecting the material matrix properties. This technology has the advantages of no pollution, simple process, and no need for solutions, and is widely used in material surface treatment.