Extrusion means putting two materials together with (co)extrusive solution from the nozzle. The solution from the nozzle can be mono, for instance polyethylene only, or can consist of two to five layers, depending on the final production structure.

The technological process of film cast by blown co-extrusion is as follows: the pre-prepared thermoplastic solution extruded by the tools for film cast ( blowing heads/ nozzles) is shaped in a cylindrical  casing  film which is further on flattened  in the system for extruding and coiled on the reel into rolls of final dimensions.
The forming of casings is carried out by supporting of the solution coming out of the annular clearance nozzle on the blowing head during the process of the extrusion by the outer and inner air circulation and blowing the desired format at the same time.

Cast films are produced from polyamide films meant for the production of high barrier packaging materials for vacuum packaging and the packaging in the interior atmosphere.
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