Multilayered, metallised or ceramic-coated, sealable, biaxially oriented polyester film, process for its manufacture and its use

摘要

Transparent, biaxially-oriented, sealable polyester film has a sealable outer layer (A) and a metallized or ceramic-coated outer layer (C) with different roughness values and coefficients of friction, containing synthetic silicon dioxide with particle diameters of 2.5-10 and 1.5-6 microns and SPAN 98 values of 1.80 or less and 2.0 or less in (A) and (C) respectively. Coextruded, transparent, biaxially-oriented, sealable polyester film with a base layer (B) between a sealable outer layer (A) and a metallized or ceramic-coated outer layer (C), in which layer (A) shows a sealing temperature of not more than 110 degrees C and a seal seam strength of at least 1.3 N/15 mm film width. Layer (A) shows a surface roughness (Ra) of more than 60 nm and a coefficient of friction (CF) (A side/A side) of less than 0.8, and contains 500-5000 ppm synthetic silicon dioxide with an average particle diameter (d50) of 2.5-10 microns and a SPAN 98 value (scattering) of 1.80 or less. Layer (C) shows an Ra value of 30-150 nm and a CF (C side/C side) of less than 0.6, contains 1000-5000 ppm synthetic SiO2 with a d50 of 1.5-6 microns and a SPAN 98 value of 2.0 or less, and is coated with metal or ceramic material. An Independent claim is also included for a method for the production of this film by feeding the base polymers for the 3 layers into separate extruders, filtering the melts, extruding through a multilayer die to form a multilayer flat melt film, taking off the film with a cooling roll and optionally other rollers, stretching by a ratio of (2.5:1)-(6:1) in the machine direction at 80-130 degrees C and then by (3:1)-(5:1) in the cross direction at 90-150 degrees C, and then heat-fixing.