Influence of atmospheric plasma treatment on surface properties and inkjet printability of plastic packaging film

Plastic films are used in various flexible packages, such as wrappings, pouches and bags. In packages, the most important function of a packaging material is to shield the product inside the package. Plastic films give a barrier against water, water vapor, aroma, grease, oxygen, etc. In addition to barrier properties, printability is an important property in packaging applications, and especially in labels. In inkjet printing, the controlled spreading of the low viscosity ink on the substrate is essential for satisfactory print quality. This requires suitable absorption properties and controlled surface chemistry. From the point of view of printing, the dense and impervious structure of plastic film is challenging: printing inks do not penetrate into the substrate. When polymer surfaces, like plastic films, are printed, adhesion of the printing ink is essential. Durability of the printed image is important, because the image must withstand various converting operations when the package is constructed. Also the end-use of the material (label or package) requires both durability and high visual print quality.Surface treatments are used in order to produce special functional groups at the surface for special interactions with other functional groups and to increase the surface energy. The objective in this study was to compare traditional corona treatment to a novel roll-to-roll atmospheric plasma treatment (APT). The APT process offers unique advantages over existing technologies for surface treatment such as corona including more uniform and longer lasting treatment. Plasma treatment activates the surfaces without affecting the reverse sides of the substrates. Plasma also allows tailored surface activation by using different process gases, like helium and argon. Furthermore, the aim was to evaluate the effect of surface treatments on the surface properties and inkjet printability of polypropylene (PP) film.