Komposittfilm og fremgangsmåte for fremstilling derav

摘要

Biaxially stretched composite film comprises a 5-50 mu thick polyester base coated with a layer of PVA, having a polymerisation degree (DP) of more than 350, of thickness of most 0.3 mu . The base has an average rugosity (roughness) (RZ) of at most 0.3 mu on the faces coated with PVA, these faces having no more than 20 pics of high at least 1 mu and no more than 150 pics of height 0.4-1 mu . The oxygen permeability of the film is at most 3 cm<3>/m<2>/24 hrs. at 24 degrees sC and 50% RH. The mfr. of the film is also claimed and involves coating a polyester base with an aq. 4% PVA soln. of viscosity at least 4 mPa.s at 20 degrees C then heating at least 170 degrees C..