Extrusion-coated Sealing Layers on ALD-Al2O3 Coated Polymer Substrate: Interfacial and Adhesion Properties

摘要

Continuous atomic layer deposition (ALD) is a novel method of producing high-barrier aluminum oxide (Al2O3) coatings on flexible substrates. We have earlier reported the properties of these coatings in recent PLACE conferences [1-3]. This study focuses on the adhesion obtained for an extrusion-coated polymer sealing layer on the top of an ALD-Al2O3 surface. Even a few nanometer thick Al2O3 layer is able to prevent heat sealing of a packaging material. In order to enable heat sealing, such a structure needs an additional polymer layer typically produced in an extrusion coating process. In this study, the Al2O3 side of paper/polymer/ALD-Al2O3 substrates was extrusion-coated with low density polyethylene (LDPE), polylactide (PLA) and polyethylene terephtalate (PET) sealing layers. The adhesion and interfacial properties of the joint structures were measured and will be discussed. According to the results, good adhesion was achieved with LDPE coating, while the other coatings showed poor performance. The oxide surface of the ALD coating enabled good chemical bonding with LDPE, which had oxidized in the air gap during the extrusion coating process, and a strong joint was measured. A corona treatment was able to further improve the adhesion properties with all of the tested polymers.