Plasma-Modified Interfaces between Polypropylene Films and Vacuum Roll-to-Roll Coated Thin Barrier Layers

For packing applications, vacuum roll-to-roll coated polymer films overall show an excellent performance because a minimum of used material results in high barrier properties. Thin barrier layers (40-100nm) may typically reduce the O2 permeability by a factor of up to 120 (see Table 1). The structure of the interface between the polymer and the barrier is the key issue for adhesion and permeability. In order to improve them, the adhesion and permeation mechanism are to be identified. By modifying the interface with a plasma pretreatment of the polymer film, the functionality of BOPP (beaxially oriented polypropylene) films coated by Al layers can be improved. A model of the pretreatment mechanism is presented.