MATERIALS / RECYCLING PETplanet Insider Vol. 25 No. 07+08/24 www.petpla.net 15 With the technologies available, a recycling cycle from waste to food packaging is to be established. The aim is to provide tray packaging produced from recycled single and multilayer PET trays as early as 2026, which will replace today’s PET trays when they are ready for the market (Fig. 1). Municipal plastic waste is sorted using near-infrared sensors in the recycling centres. This results in waste fractions 328-1 to 328-5, which are heavily enriched with PET, the latter consisting mainly of PET trays. This waste is usually cut into flakes and washed for further processing. This task is tackled by ZWS Recycling. Due to the higher stiffness and brittleness of PET trays compared to PET from bottles, a large amount of fines accumulate during washing, which are often of limited use for further processing. A reduction in fines is to be achieved by developing suitable washing technologies with a design optimised to minimise material breakage. With Unisensor’s flake-based sorting technology, the flakes are sorted into a high-purity single-layer PET fraction and a multi-layer PET fraction, both of which are ready for further processing by mechanical and solvent-based recycling. The Fraunhofer IVV’s solventbased recycling aims to selectively remove the non-PET components from the multi-layer flakes to produce pure PET flakes. Previous projects have already demonstrated the applicability of such a process for mixed plastics. In an earlier project, PET flakes were obtained that are suitable for the production of films. With this film, it was also possible to produce three-dimensional trays using a thermoforming process (Fig. 2). This solvent-based recycling process, which is currently being carried out on a small technical scale, is to be scaled up to the size of a pilot plant in order to gain deeper insights for further scaling up to an industrial scale. At the same time, packaging orientated to the “Design for Recycling” guidelines is being developed that can contain a recycled content that exceeds the prescribed minimum. Such a design requires functional barrier technologies to ensure that there is no contact between the product and the rPET, as required by European legislation and necessary for modified atmosphere packaging. Suitable functional barrier technologies that prevent the migration of substances from rPET into the product during the typical storage period have already been identified and investigated prior to this project. Of the functional barrier technologies investigated, coextruded virgin PET film, PET lacquer, laminated virgin PET film and SiOx coating, both laminated virgin PET film and SiOx coating offer similar performance, although only laminated PET film can be thermoformed after application. Usually PE and EVOH are used for such barriers, but to make this packaging mechanically recyclable, a laminated PET film is chosen as the functional barrier. After washing and processing, processed and purified mono- and multilayer waste PET fractions are to be turned back into a film consisting of a sandwich structure with at least one laminated PET virgin material layer for food contact. Once Reifenhäuser has obtained the films, silverplastics will thermoform them into new trays, which can be tested on existing packaging lines. In order to prove suitability for food contact, the recyclate is analysed for non-intentionally added substances (NIAS) and the barrier is tested using a migration test in order to collect data for modelling potential storage durations. In order to demonstrate the ecological viability of the recycling chain, the processing chain is analysed and evaluated by the Öko-Institut using a life cycle assessment, whereby the recycling scheme competes with incineration with energy recovery and the production of new, modern virgin PET trays. A use case with a recyclate content of 66 per cent by weight and at least one additional life cycle is assumed. In addition, the production of the developed packaging is evaluated from an economic point of view. As the status of recycling technologies for PET trays poses a significant problem for the entire value chain involved with PET trays, cooperation is welcome. Quarterly meetings are planned for all those involved in the PET tray value chain. www.ivv.fraunhofer.de Fig. 2: From PET tray flakes to new PET trays by solvent based recycling
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