Today we will talk about how to improve the adhesion of plastic parts coating? The most important link to improve the adhesion of car plastic injection mould coating is pre-painting. The purpose of pretreatment of automotive plastic parts is to improve the adhesion of coatings to plastics and reduce various defects of coatings through a series of physical and chemical methods, thereby improving the quality of plastic coatings. The pretreatment of plastic parts paint includes conventional treatment, acid treatment, flame treatment, surfactant treatment, hot solvent treatment, ultraviolet treatment, and plasma treatment. Today I will introduce two of them: flame treatment and plasma treatment.
The flame treatment method is also known as the flame oxidation method. Because the surface of the plastic is low in polarity and small in tension, if it is not handled properly, it is difficult to achieve the expected effect of the painted protrusions. The flame treatment method can increase the polarity of the plastic surface. Flame treatment is to spray the flame on the surface of the plastic, and after a very short period, the surface temperature of the plastic reaches 1000-2800 ° C, which can instantly change the properties of the plastic surface, so that the molecules on the surface of the plastic are partially oxidized so that the molecules on the surface of the plastic are "- C=O", "-COOH" and other hydrophilic groups, which can significantly increase the polarity of the plastic surface, thereby improving wettability and adhesion. Note that the flame spray time must be extremely short, measured in seconds, to avoid plastic damage and melting.
The plasma treatment method is referred to as electrostatic treatment. The working principle is to use an electrostatic ion generator to generate high-voltage high-frequency energy so that low-temperature plasma is generated by low-light discharge. The negative charge forms an airflow of positive and negative charges, and the airflow is sprayed to the surface of the plastic part with the help of compressed air to eliminate the static electricity on the surface of the plastic part and remove the hydrocarbon dirt on the surface of the plastic part.
To improve the adhesion of the coating, the surface treatment and construction environment of the plastic parts before painting should be strictly controlled during the construction process to ensure the coating quality. If necessary, change the pretreatment process and primer variety.