The performance of plastics has been continuously improved, allowing plastic parts to gradually penetrate various industries. Currently, the annual demand for injection mold processing in the fields of building materials, automobiles, household appliances, electronics, etc. remains relatively strong. The rapid development of these industries has also brought the plastic industry, especially, into a stage of rapid growth.
In the production of automotive parts, the issue of coating adhesion on plastic products is a crucial process measure. To address the problem of coating adhesion on automotive plastic parts, one must have an understanding of the coating process for automotive plastic parts. According to the author's compilation and collection, the process flow of automotive plastic parts can be roughly divided into the following sections:
Blank grinding - chemical treatment - dust removal - spraying primer - spraying color paint (or metallic paint) - spraying topcoat - baking - inspection - qualified products stored - unqualified products repaired or de-painted.
It is understood that among the numerous process steps, the most crucial aspect for enhancing the adhesion of plastic parts coating is the pretreatment before painting. The purpose of pretreatment for automotive plastic parts before painting is to improve the adhesion of paint to plastic through a series of physicochemical methods, reduce various defects in the coating, and thereby enhance the quality of the plastic coating. Pretreatment for plastic parts before painting includes conventional treatment, acid treatment, flame treatment, surfactant treatment, hot solvent treatment, ultraviolet treatment, and plasma treatment.
In addition, to improve the adhesion of the coating, it is necessary to strictly control the surface treatment and construction environment of plastic parts before coating during the construction process to ensure the quality of coating. When using new plastic materials, attention should be paid to improving their surface tension and polarity. If necessary, the pre-treatment process and primer type should be changed.
