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Packaging materials are typically made of multilayer structures combining polymers, metals and inorganic materials. Multilayer structures are selected in order to optimize the thickness and performance in packaging applications. Atomic layer deposited (ALD) aluminium oxide (Al2O3) layer provides good barrier properties against oxygen and carbon dioxide gases i.e. permeation of gases through ALD coated polymer films will reduce remarkably. The target was to study the effect of pinholes on the oxygen and carbon dioxide permeability of ALD coated extrusion-coated packaging paper. Pinholes were artificially generated by ultra violet (UV) laser drilling through the polymer layer prior to Al2O3 ALD coating. The results show, that even one pinhole through the structure can destroy the excellent barrier properties of the film material. It was found out that the size of a pinhole affects detrimentally the oxygen gas permeation through the material. According to the results, there is a linear correlation between permeation rate of oxygen gas and area of pinhole, thus, oxygen barrier level can be calculated and adjusted by the size of pinhole.
Johansson, Petri; Lahti, Johanna; Vihinen, Jorma; and Kuusipalo, Jurkka
"Permeability of Oxygen and Carbon Dioxide Through Pinholes in Barrier Coatings,"
Journal of Applied Packaging Research: Vol. 11:
2, Article 4.
Available at: https://scholarworks.rit.edu/japr/vol11/iss2/4