Can You Finally Get Foil Barrier Properties With a Metallized Film?, 2004 PLACE Conference

Application: Using a new high oxygen barrier primer with metallized PET structures can provide oxygen barrier resistance very similar to foil.

Executive Summary: The idea of replacing foil with metallized PET appeals to many converters. The cost with the ease of extrusion laminating and flexibility advantages of metallized PET over foil make it ideally suited for certain applications. Important remaining obstacles for metallized PET are its relatively poor oxygen and water vapor barrier properties relative to foil. Recently, a potential high oxygen barrier primer has become available. Application is with direct or offset gravure coating. This paper reports on the work pursued to combine this new primer with various metallized PET structures to determine the improvements in barrier that might be possible with this composite barrier system.

This work used resistive evaporation in a free span vacuum metallizer to apply thin layers of aluminum to the non-treated surface of one-side corona treated PET film. Some metallized and some unmetallized film were then coated with the oxygen barrier primer at a pilot coating facility using direct gravure application.

Based on barrier testing, the various primer/metal combinations tested in this work provide excellent oxygen barrier. It is approximately the same order of magnitude as foil. The primer actually inhibits the water vapor barrier capability of the metal layer. The nature of this primer makes it unsuitable for use with metallized PET in liquid packaging applications or for applications where these layers might be exposed to high levels of ambient humidity. One primed and metallized PET structure studied here would be ideally suited for dry, oxygen-sensitive packaging applications.