Developments in the extrusion of blown film structures:
Convincing 5-layer technology offers high flexibility

The trend in blown film extrusion is clearly towards improved flexibility and customised products. An optimised technology that encompasses all up-to-date developments in the hot part and film guiding section enables the production of both barrier and polyolefin packaging films on a 5-layer line. In addition to the possibility to produce a wide range of products, it offers cost advantages when, for example, 3-layer polyolefin films commonly found on the market are substituted for 5-layer structures using inexpensive raw materials. Improved film properties that can be obtained in many cases are a further factor of success in the marketplace. 

Blown film die-heads are available in diameters from 200mm to 1200mm. Beside the typical layer structures from 1:1:2:1:1 to 3:1:1:1:3 they enable the production of extreme combinations of 9:1:1:1:9. This gives the film producers the flexibility to process a wide spectrum of polyolefins and barrier films with symmetric and asymmetric structures of EVOH, PA and CoPET.
But also classical barrier films laminated and refined with BOPP, BOPA,  BOPET, etc.  in subsequent processing steps can be produced using the 5-layer technology. 

Market trends to produce for example collation shrink film and laminating and hygienic packaging films with five layers can already be observed. Changes in raw material combinations offer price advantages of 5% to 10% for identical film thicknesses. Cost savings that can be additionally obtained by reducing the film thickness are not yet included herein. 
Further applications of 5-layer barrier film structures are food and medical packagings, for example stand-up pouches, lidding film for cups, flow packs, bags-in-boxes, etc.

For the extrusion grooved feed extruders with low melt temperature barriere screw design is applied.Unique is the design of the heating-/cooling combination of the feed section, which allows for a wide processing range.

Design series with output capacities from 600 kg/h to 1200 kg/h are available for different applications.