Thin Al2O3 Barrier Coatings Grown on Bio-based Packaging Materials by Atomic Layer Deposition

Author
Terhi Hirvikorpi
Year
2011
Abstract & Cover

Growing environmental concerns related to the use of synthetic non-biodegradable polymers in the packaging industry have led to the need for new, especially bio based, materials. Currently, petroleum-based synthetic polymers are widely used due to their relatively low cost and high performance. Biodegradable plastics and fibre-based materials have been proposed as a solution to the waste problems related to these synthetic polymers. Fibre-based packaging materials have many advantages over their non-biodegradable competitors, such as stiffness vs. weight ratio and recyclability. However, poor barrier properties and sensitivity to moisture are the main challenges restricting their use. Application of a thin coating layer is one way to overcome these problems and to improve the barrier properties of such materials. Atomic layer deposition (ALD) is a well suited technique for depositing thin inorganic coatings onto temperature-sensitive materials such as polymer-coated boards and papers and polymer films. In the present work, thin and highly uniform Al2O3 coatings were deposited at relatively low temperatures of 80, 100 and 130 °C onto various bio-based polymeric materials employing the ALD technique. The study demonstrates that a 25-nm-thick ALD-grown Al2O3 coating significantly enhances the oxygen and water vapour barrier performance of these materials. Promising barrier properties were obtained with polylactide-coated board, hemicellulose-coated board as well as various biopolymer (polylactide, pectin and nanofibrillated cellulose) films after coating with a 25-nm-thick Al2O3 layer. Thin Al2O3 coatings can improve the properties of biopolymers, enabling the use of these renewable polymers in the production of high-performance materials for demanding food and pharmaceutical packaging applications. The future roll-to roll ALD technology for coating polymers with inorganic thin films will increase the industrial potential of these materials and could lead to further opportunities for their commercialization. 

Source of Information
FinALD40 exhibition material, http://www.aldcoe.fi/events/finald40.pdf
University
VTT Technical Research Centre of Finland / Aalto University
(Espoo, Finland)
External Link
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