Biaxially oriented laminated polyester film, process for its manufacture and use of it for the packaging of food

摘要

The biaxially oriented coextruded polyester film has a base layer and at least one outer layer containing inert particles, in which the number of high spots or projections per unit area of film is related to the height and diameter of these projections by two given equations. The biaxially oriented, coextruded polyester film comprises a base layer (B) containing at least 80 wt% thermoplastic polyester together with other layer(s), in which at least one outer layer (A) contains internal and/or inert particles and shows a number of high spots/projections (N/mm<2> of film surface) which is related to the respective heights (h) and diameters (d) by the following equations: log N/mm<2> = less than Ah - Bh asterisk log h/micron, h = 0.01-10 microns (1) Ah = 1.4; Bh = 2.5 log N/mm<2> = less than Ad - Bd asterisk log d/micron, d = 0.4-10 microns (2) Ad = 3.4; Bd = 2.4. An Independent claim is also included for a process for the production of film which meets the above specification, in which polyester melts for the base and outer layers are extruded from a coextrusion die onto a cooling roller and the composite film is then stretched in 2 directions and heat- fixed.