Patent ID: 7563399
Filing Date: 2009-07-21
Classification: B29C,B29K,B29L,B32B,Y10T

Abstract:
1. A method for manufacturing a multilayer biaxially oriented film which comprises at least five layers having the arrangement A/B/C/B/A, the inner layer C being synthesized from an ethylene-vinyl-alcohol copolymer (EVOH layer) and an adhesion promoting layer B made of modified polyolefin being applied on both sides on each surface of the EVOH layer C and a layer A made of a partially crystalline thermoplastic polyolefin being applied to the surfaces of the particular adhesion promoting layers, characterized in that the melts corresponding to the individual layers of the film are coextruded through a sheet die, the multilayer film thus obtained is drawn off on one or more roll(s) for solidification, the film is subsequently stretched in the longitudinal direction and then in the transverse direction using a tenter frame, the EVOH layer C and the adhesion promoting layers B and the layer A are coextruded at the same width, and the tenter hooks of the frame engage all five layers jointly and simultaneously during the transverse stretching and wherein the EVOH layer has a thickness of at most 10 μm.