Dehnungstolerante PECVD-Barrierebeschichtungen für flexible Verpackungsanwendungen
Bei der Entwicklung nachhaltiger Kunststoffverpackungen sind Plasmabeschichtungen für den Einsatz als Gas- und Wasserdampfbarriere ideal geeignet. Dem gegenüber steht ihre geringe Dehnungstoleranz, durch die sie für Anwendungen mit erhöhter mechanischer Belastung nur begrenzt geeignet sind. Hier setzte das DFG-Projekt StrainCoat an, bei dem Schädigungsmechanismen sowie mögliche Gegenmaßnahmen erforscht wurden.
By specifically adjusting the process parameters, PECVD (Plasma Enhanced Chemical Vapor Deposition) allows both silicon oxide (SiOx) and silicon organic (SiOCH) coatings to be deposited one after the other. SiOx coatings have a glass-like structure with excellent barrier properties, but tend to crack early. SiOCH layers with a higher organic content enable more flexible network structures, but at the expense of the barrier effect.
Based on this, multilayer systems were developed that combine hard SiOx barrier layers with softer SiOCH intermediate layers (Fig. 1). This structure is intended to extend the diffusion path by decoupling the formation of cracks in individual layers. Simulations showed that this effect can reduce permeation by up to 81% with two barrier layers compared to a single layer of the same overall thickness.
The tests achieved an improvement in elongation tolerance compared to single layers. Nevertheless, the system remains vulnerable: microscopic images showed that just 1.4 % of the open area leads to complete barrier loss due to cracking. The discrepancy between minor visible damage and drastic loss of function points to additional, previously unidentified failure mechanisms in the nanometer range.
© IKVProject data and funding
We would like to thank the DFG for funding the project (funding reference DA 488/3-1) and the project partners for their cooperation.
Project duration: 01.10.2022 – 30.09.2025
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