Structure and oxygen-barrier properties of metallized polymer film

Abstract

The structure of thin (10 to 50 nm) aluminium layers vacuum deposited on to polyester film is examined using both transmission electron microscopy and light microscopy. The density of pinhole defects in the aluminium coating, quantified by an image analysing microscope, is shown to determine the permeability of the film to oxygen. Finite element calculations of the effect of various pinhole diameters and densities on the permeability agree with experiment, and also show that the barrier properties of the polymer layers immediately adjacent to the metal coating are critical in determining the deleterious effect of pinhole defects. © 1983 Chapman and Hall Ltd.