Atomic Layer Deposition of Metal Oxide Films as Diffusion Barriers on Flexible Packaging Materials

摘要

One of the most promising areas for the industrial application of atomic layer deposition (ALD) is gas diffusion barriers on polymer based materials. In this work a novel packaging material system with improved diffusion barrier properties has been developed. Nanometer scale metal oxide films have been applied to paper-based packaging materials and their diffusion barrier properties have been studied by means of water vapor and oxygen transmission rates. The paper is firstly extrusion coated with polymer film followed by ALD deposited A1_2O_3. The polymers used as extrusion coatings were polypropylene, low and high density polyethylene, polylactide and polyethylene terephthalate. Water vapour transmission rates (WVTRs) were measured according to method SCAN-P 22:68 and oxygen transmission rates according to a standard ASTM D 3985. A 10 nm oxide layer already decreased the oxygen transmission by a factor of 10 compared to uncoated material. WVTR with 40 nm ALD layer was better than the level currently required for most common dry flexible packaging applications. When the oxide layer thickness was increased to 100 nm and above, the measured WVTRs were limited by the measurement set up. Using an ALD layer allowed the polymer thickness on flexible packaging materials to be reduced. Once the ALD layer was 40 nm thick, WVTRs did not improve with increasing polymer layer thickness. Thus, nanometer scale ALD oxide layers have been shown to be an effective way to fabricate flexible packaging materials with high quality barrier properties.