Mono-layered, biaxially oriented polyester film, process for its manufacture and its use

摘要

A single layer biaxially oriented polyester film of planar orientation DELTA p greater than 0.166 containing at least 80 wt.% thermoplastic polyester and internal and/or inert particles (e.g. metal particles) is new. Independent claims are included for: (1) a process for the preparation of the film in which the polyester melt is fed to a wide slot nozzle and is extruded onto a cooling roll. The prefilm obtained is biaxially stretched and heat hardened, with the planar orientation DELTA p of the film greater than 0.166; and (2) a process for the preparation of biaxially oriented polyester film in which regenerated material is fed to the extrusion nozzle at a concentration of 10-50 wt.% relative to the total weight of film.