Development of PECVD Migration Barrier Coatings Using Model Recyclates

The ecological-driven sustainability of plastic materials encounters a major challenge in eco-efficient mechanical recycling falling short of meeting the required quality and quantities of post-consumer recyclates (PCRs) in sensitive application areas demanded by regulatory authorities. Those toxicological residues of contaminants that remain after mechanical recycling restrict PCRs use in sensitive application areas. Addressing the integration of PCR into high-demand applications such as food contact materials, this work investigates a novel technology for PCR product use by an innovative migration barrier development pathway of Si-based plasma-enhanced chemical vapor deposition (PECVD) coatings on pre-contaminated polypropylene (PP) model PCR cups, developed with consideration of applicable regulatory frameworks, including European Food Safety Authority (EFSA) requirements for food contact materials. As a starting point for migration barrier development, suitable oxygen transmission rate (OTR) barrier coatings for PCR cups were reproduced and transferred on virgin and model PCR PP cups. The coating procedure consisted of a pretreatment, an applied organic adhesion interlayer SiOCH and an inorganic functional barrier layer SiOx, where the functionality was related to the applied SiOx layer based on the barrier efficiency. Therefore, SiOx was varied in the migration barrier development to find a suitable process window and efficiently correlate the effects of process parameters on OTR before and after migration testing, mass loss of simulant and the reduction in migration of eight introduced contaminants in the model PCR cup using GC/MS. This work advanced the understanding of PECVD for migration barriers under regulatory frameworks and reduced PCR matrix complexity in the analysis during development using model PCR cups.