TY - JOUR
T1 - Mechanical recycling of printed flexible plastic packaging
T2 - The role of binders and pigments
AU - Lisiecki, M.
AU - Belé, Tiago G.A.
AU - Ügdüler, S.
AU - Fiorio, R.
AU - Astrup, T. F.
AU - De Meester, S.
AU - Ragaert, K.
N1 - Funding Information:
This research received funding via the C-PlaNeT (Circular Plastics Network for Training) project as part of the European Union's Horizon 2020 research and innovation program under Marie Sklodowska-Curie grant agreement No. 859885. The authors would like to thank Siegwerk for their donation of the samples and their insights into ink formulations. The author acknowledges the contributions of researchers from the Circular Plastic group at Maastricht University, especially Andona Dimitrova and Ali Ebrahimi.
Publisher Copyright:
© 2024 The Authors
PY - 2024/7/5
Y1 - 2024/7/5
N2 - 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 LDPE-based 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.
AB - 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 LDPE-based 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.
KW - Design for circularity
KW - Mechanical recycling
KW - Solvent-based ink
U2 - 10.1016/j.jhazmat.2024.134375
DO - 10.1016/j.jhazmat.2024.134375
M3 - Article
SN - 0304-3894
VL - 472
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
M1 - 134375
ER -