INFLUENCES AND CONSEQUENCES OF MECHANICAL DELABELLING ON PET RECYCLING

Abstract

The recycling of polyethylene terephthalate (PET) is an important issue of today’s society. Mechanical recycling makes more sense from an ecological point of view than chemical PET recycling. However, mechanical recycling still is highly susceptible to defilements. Therefore, intensive pre-treatment is necessary to ensure the mechanical production of high-quality recycled PET. An important step in this process is to separate the PET bottles from their labels/sleeves. For this purpose, a newly developed label remover was studied. In this study, it was found that the machine had a delabelling efficiency of 90 w%. The PET bottles that were not sufficiently delabelled (10 wt.%) on average had a significantly smaller bottle size. This means that a sharp screening step, prior to delabelling, could improve the delabelling efficiency furthermore. Additionally, the applicability of near-infrared sorting technology was tested to find out, whether it can be used for quality control. Tests showed that state-of-the-art technology could differentiate between labelled and delabelled PET bottles, enabling separation of labelled PET bottles from delabelled bottles via sensor-based sorting. Hence, the proportion of contaminated PET bottles could be reduced furthermore with additional processing steps.