Plasma activation of various industrially used materials for UV-digital printing applications

Plasma activation of polymer materials is still one of the hot topics in modern industrial processing. Several applications are eager for enhanced surface properties of materials with excellent bulk properties. One of such fields is UV-digital printing for outdoor applications such as advertisement tables, safety labels, name tags, etc. In our work, we focused on plasma activation of materials commonly used for UV-digital printing, such as polyvinylchloride, polycarbonate, polymethylmethacrylate, and “di-bond” (polyethylene-aluminium composite material). We studied the wetting properties of the treated surface via water contact angle and free surface energy measurements. As expected, all materials reacted to the air plasma activation with a significant increase of the free surface energy. Most notably, the di-bond (PE-Al) material free surface energy value was changed by more than 50 %. In real-life applications, surface adhesion is most important. Thus, we studied the change in adhesion before and after plasma activation by peel test measurements. We confirmed the influence of air plasma on this parameter for all studied materials. We achieved an increase of adhesion on some materials by more than 100 %. Additionally, we analyzed the morphology of treated surfaces. Several air plasma sources have been tested for the potential application and incorporation in the UV-digital printing machine prototype.