Although PVC should be better wetted with a significantly higher surface tension than PE / PP and paint films should generally adhere better because of their polar structure, the adhesion of paint films is often made difficult by high levels of plasticizers, stabilizers and process auxiliaries. The adhesion can therefore be very different depending on the composition and manufacturing process of the PVC and must always be checked in individual cases. A significant improvement in adhesion can frequently be achieved with difficult PVC types by removing the interfering substances by means of plasma or corona treatment. The preheating of the PVC also leads to paint adhesion.
In order still to establish adhesion, the surface of the base material is often polarized by means of “Corona treatment” or flame treatment. UV primers have the purpose to provide a good adhesive join to the substrate (vinyl) in case there is no pre-treatment available.