Article,
Mechanical recycling of printed flexible plastic packaging: The role of binders and pigments
Affiliations
- [1] Maastricht Univ, Fac Sci & Engn, Dept Circular Chem Engn CCE, Circular Plast, POB 616, NL-6200 MD Maastricht, Netherlands [NORA names: Netherlands; Europe, EU; OECD];
- [2] Tech Univ Denmark, Dept Environm & Resource Engn, Bldg 115, DK-2800 Lyngby, Denmark [NORA names: DTU Technical University of Denmark; University; Denmark; Europe, EU; Nordic; OECD];
- [3] Friedrich Alexander Univ Erlangen Nurnberg FAU, Chair Aroma & Smell Res, Dept Chem & Pharm, Henkestr 9, D-91054 Erlangen, Germany [NORA names: Germany; Europe, EU; OECD];
- [4] Univ Ghent, Dept Green Chem & Technol, Lab Circular Proc Engn, Graaf Karel Goedelaan 5, B-8500 Kortrijk, Belgium [NORA names: Belgium; Europe, EU; OECD];
- [5] Ramboll, Hannemanns Alle 53, DK-2300 Copenhagen, Denmark [NORA names: Ramboll Group; Private Research; Denmark; Europe, EU; Nordic; OECD]
Abstract
Low -density polyethylene (LDPE), extensively employed in flexible plastic packaging, often undergoes printing with inks. However, during the mechanical recycling of post -consumer waste, these inks act as contaminants, subsequently compromising the quality and usability of recycled material. To understand better exactly which ink components cause which effects, this study comprehensively assesses the thermal behavior of three organic pigments and two commonly utilised binders, correlated with the impact on the mechanical recycling of LDPEbased flexible plastic packaging. In this regard, the study focuses on four pivotal factors: processability, mechanical properties, aesthetic attributes, and volatile organic compound profiles. The results indicate that nitrocellulose, used as a binder, degrades during reprocessing, resulting in film discoloration and the emission of potentially odorous compounds. Conversely, pigments are found to be dispersed within droplets of polyurethane binder in LDPE recyclates, whilst reprocessing printed samples detrimentally affects film properties, notably dart drop impact resistance, strain at break, and the number of inclusions. Additionally, it is shown that both inks comprise components that emit volatile compounds during reprocessing: non -thermally stable components, nitrocellulose and pigment yellow PY13, as well as low -molecular weight molecules from polyurethane and by- products from wax, plasticisers, and additives.