Coextruded and biaxially oriented polyester film comprises a thermoplastic polyester base layer sandwiched between a heat-sealable layer and a matt layer and includes an ultraviolet absorber

摘要

Coextruded and biaxially oriented polyester film comprises a thermoplastic polyester base layer sandwiched between a heat-sealable layer and a matt layer. Coextruded and biaxially oriented polyester film comprises a thermoplastic polyester base layer sandwiched between a heat-sealable layer and a matt layer, where: (a) at least one of the layers contains an ultraviolet (UV) absorber; (b) the heat-sealable layer has a minimum weld temperature of 110[deg] C, a weld strength of at least 1.3 N/15 mm, a surface roughness of less than 30 nm and a superficial gas flow time of 500-4000 seconds; and (c) the matt layer has a surface roughness of 200-1000 nm and a superficial gas flow time of less than 50 seconds. An independent claim is also included for a process for producing the film, comprising coextruding melts corresponding to the individual layers through a flat nozzle, withdrawing the film over one or more rollers, biaxially stretching the film, and thermofixing the film.