Transparent polyester film having a high oxygen barrier and process for its production

Abstract

The invention relates to a transparent, biaxially oriented polyester film with a base layer B, at least 80% by weight of which is composed of a thermoplastic polyester, and with at least one outer layer A. The outer layer A is composed of a copolymer or a mixture of polymers/copolymers which contains ethylene 2,6-naphthalate units in a range of from 90 to 98% by weight and up to 10% by weight of ethylene terephthalate units, and/or units derived from cycloaliphatic or aromatic diols and/or dicarboxylic acids. Its thickness is more than 0.7 μm and makes up less than 25% by weight of the total film and the Tg2 value of the polyester film is above the Tg2 value of the base layer, but below the Tg2 value of the polyester for the outer layer. The transparent film has low permeability to atmospheric oxygen and exhibits very good adhesion between the individual layers. It is particularly suitable for packaging purposes, specifically for packaging foods or other consumable items.

Dependencies are inferred from the claim text.