Biaxially oriented polypropylene films are polymer films manufactured by extrusion followed by biaxial orientation. BOPP films are multi-layer films with polypropylene core and tie layers. Orientation in two perpendicular directions ensures that BOPP films have good mechanical properties in both directions. The outer surfaces of BOPP films are formed by co-extrusion with skin co-polymer layers (either on one or on both sides).
Film layers may consist of a mix of polymers and functional additives that adjust barrier properties, opacity, whiteness, matting or gloss, thus controlling film properties, and therefore defining the range of available film products. In addition to co-extrusion, both or one of the film surfaces may be corona- or flame- treated to activate them and make suitable for printing and lamination.