The extrusion of Cast Films by the flat die technique is becoming more and more important in view of its superior performance: throughput of more than 1 ton per hour against a few hundred kilogram’s per hour for the circular die technique, and better control of the distribution of layer thickness in the transverse direction.
As in the case of bi-oriented films, the technique of multilayer co-extrusion allows for 3, 5 or 7 layers within complex structures.
The material temperature recommended for manufacturing is situated between 230 and 280°C when using a flat die and between 180 and 210°C for a circular die, with water-cooling of the tubular film; higher temperatures must be avoided as they may cause degradation of the additives.
Cast polypropylene films are used for the packaging of foodstuffs, textiles, the production of stationery, simulated leather goods, as well as for the manufacture of complex films by lamination or co-extrusion coating.