Polyolefins polyethylene blown film

Since the packaging is the world s most widespread polymer application, with the Europe plastic total demand of almost 40 % [41], the blown film process, sketched in Fig. 4.1, is the most diverse conversion procedure where polyolefins, namely polyethylenes, play the major role. 

Cast film extrusion is used in manufacturing polypropylene films and requires greater surface pretreatment power density (possibly 2-3 times) compared to other polyolefin films. With blown film extrusion processes, polyethylene films are typically used and require pretreatment on both sides. Considerable amounts of slip additives, used to lubricate the surface of these films for processing ease, can be prevalent within the resin and migrate to the surface of the film within a few days after extrusion. Although there is potential for the additive to mask-over treatment, it is far more important to surface treat immediately after extrusion, since it will be practically impossible to do so after additive migration to improve surface properties sufficiently for ink, coating, or lamination adhesion. 

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