Abstract: Extensible multilayer film comprising two external layers made of thermoplastic polyolefinic resins, two optional intermediate adhesive layers and one central layer; the said external layers being realized with ethylene/?-olefins copolymers resins, the said optional intermediate layers being realized with adhesive resins preferably containing linear low density polyethylene modified with polar groups, ethylene vinylacetate terpolymers, or maleic anhydride modified ethylene acrylate, the said central layer being realized with resins which impart to the film, sinergetically with the other components of the same film, the following features: glass transition temperature in a range between 20 and 70° C.; longitudinal strain greater than 200%, at a temperature comprised between 25 and 45° C., applying reduced load, less than 0.5 N/mm; necking in the range of the 40-60%; longitudinal thermo-shrinkage in the range of 40-60%; residual elastic memory, giving rise to a longitudinal force less than 0.

Abstract: A stretch film presenting controlled permeability to gases, manufactured by process of balloon co-extrusion and consisting of outer layers (S2) of stretchable polmeric material and by one or two inner barrier layers (S3) of a EVOH based polymeric matrix, which is made stretchable by the addition of a suitable plasticizer in such a percentage as to conciliate the stretchablity with the desired barrier effect, said layers of different material being reciprocally secured by means of layers (S4) of adhesive material. The polymeric matrix which forms the barrier material and the plasticizer are intimately mixed inside a double-screw corotating extruder, immediately before the phase of co-extrusion, through a premelting of the polymeric matrix and the subsequent injection of the plasticizer in liquid phase.

Abstract: A stretch film presenting controlled permeability to gases, manufactured by process of balloon co-extrusion and consisting of outer layers (S2)of stretchable polymeric material and by one or two inner barrier layers (S3) of a EVOH based polymeric matrix, which is made stretchable by the addition of a suitable plasticizer in such a percentage as to conciliate the stretchability with the desired barrier effect, said layers of different material being reciprocally secured by means of layers (S4) of adhesive material. The polymeric matrix which forms the barrier material and the plasticizer are intimately mixed inside a double-screw corotating extruder, immediately before the phase of co-extrusion, through a premelting of the polymeric matrix and the subsequent injection of the plasticizer in liquid phase.