Coextruded films have found room for development because of the characteristics of strength and barrier effect not found on single-layer films. As matter of fact, the sum of all physical-mechanical properties of more layers in a co-extrusion film, even equal, will always provide a superior result respect to a mono-layer film of equal thickness, so mechanical strenght and barrier effect (due to the total absence of micro-holes which otherwise will be present on a mono-layer film) are enhanced.
We design and build two-layer co-extrusion heads, with IBC, built in such way that the material coming from a single-screw extruder, by way of separate channels, is fed in two independently spyral distributors. The two layers are joined together before coming out of the die in order to be contemporarily laminated and cooled: it is possible, therefore, to extrude two-layer films of same material and color, equally thickness distribution respect to the total.
The internal bubble cooling system (IBC), together with the inner side of bubble air cooling, ensures a better control of film temperature, when coming out of the die, with a clear reduction of the difference between the inner and outer side of bubble: in this way an increase in mechanical strength is obtained due to a better film stabilization during cooling period.
During suction of hot air from inside the bubble, the fumes loaded with wax and paraffins deposits, created by extrusion temperature effect, are eliminated in a great deal.
As a result, a wax free product is obtained, improving film optical characteristics and the hygiene factor for food packaging.
The most typical application for this double-layer film is that of generic packaging, liquid or semi-liquid packaging and film for agricultural purposes.
It is also used for food packaging such as fresh milk, short-lived cheeses and freezer bags for family use.
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