Advances in blown film extrusion, including a special die developed by Reifenhäuser (Troisdorf / Germany; www.reifenhauser.com) for the substitution of three-layer films by five-layer alternatives, will be on display at “K 2007” (24-31 October 2007, Düsseldorf / Germany), the international plastics and rubber trade fair.

As modern blow films have to perform an increasing number of functions, particularly for food packaging applications, more layers are being added in the film. Multiple layers are essential to guarantee the entire range of functions such as protection from sunlight and oxygen, guaranteed taste and aroma, sealability and printability, say the organisers of “K 2007”.

Reifenhäuser sees the substitution of the still widespread three-layer films by five-layer alternatives as an opportunity to improve the cost efficiency of existing blown film lines. The company’s new die has spiral mandrels designed to produce thin layers, offering flexibility in the production of polyolefin films and in the processing of barrier materials such as EVOH, PA and co-PET.

Windmöller & Hölscher (W&H, Lengerich / Germany; www.wuh-lengerich.de) has launched a five-layer blown film die, “Maxicone”, which the equipment manufacturer believes could eventually replace conventional three-layer dies. W&H also supplies a nine-layer Maxicone die.

Kiefel Extrusion (Worms / Germany; www.kiefel-extrusion.com) also sees good growth opportunities for multilayer technologies. The company has introduced an “MDO” (machine direction orientation) module, upgrading the technology of its “Kirion” film blowing lines. The MDO version – which consists of a heating zone, a stretch zone and a temperature-control and cooling zone – reduces the film thickness, saving on raw materials.