Patent ID: 7229581

Claim:
A process for producing a single-layer or multilayer film, said process comprising (i) extruding or coextruding a single crystallizable thermoplastic polymer and/or copolymer comprising a principal constituent and a secondary constituent; (ii) biaxially orienting the extrudate or co-extrudate; (iii) heat setting the biaxially oriented extrudate or co-extrudate, said process further comprising mixing the principal constituent with up to less than 50% by weight, based on the total weight of the thermoplastic, of the secondary constituent, said mixing step performed prior to or during said extrusion or coextrusion step, wherein the principal constituent has a standard viscosity SV (DCA) of from 600 to 1 000, the secondary constituent has a standard viscosity SV (DCA) of more than 900 to 1 500, the standard viscosity SV (DCA) of the secondary constituent is higher than that of the principal constituent by at least 100 units, and the secondary constituent is recycled polymer.