CEFLEX tests NIR tech for sorting multi-layered flexible packaging

29 Jul 2022 --- CEFLEX is conducting a research program on Near Infrared (NIR) technology’s ability to sort multi-layered flexible packaging for the recycling sector. The study is being conducted in collaboration with a network of leading laboratories, universities and industry experts and will contribute to CEFLEX’s “Designing for a Circular Economy” guidelines.

NIR technology is traditionally used to conduct medical and physiological diagnostics and research, including blood sugar, pulse oximetry, functional neuroimaging and sports medicine. The program aims to apply this technology to flexible packaging structures and increase understanding of how different materials and elements affect sortability and recyclability.

CEFLEX’s work to apply this technology to packaging is part of a major partnership with UK Research and Innovation to co-fund investigations into how flexible packaging can be designed for existing sorting and recycling infrastructure across Europe.

Dennis Bankmann, a workstream consultant at CEFLEX, remarks: “By bringing together leading testing laboratories and the wide representation of industry in CEFLEX, we were able to conduct testing on a large number of well-described packaging structures in a single consistent approach while capturing all layers of information, from the ‘raw’ NIR spectrum that the sorting machine records to classification outcomes.”

Flexible packaging samples used by CEFLEX.“This allows to both refine the understanding of how design decisions impact sortability as well as identify additional potentials for improved sorting.”

NIR sorting data
More than 200 samples were tested to understand the abilities and limits of NIR sorting technology to sort various flexible packaging structures, including multi-material-multi-layer (MMML) structures.

The program specifically aims to understand how NIR classifications are affected by film thickness, different shares of materials in an MMML structure; differences in layer sequence for transparent and opaque structures; and differences in surface reflectivity of packaging films.

The testing encompasses a wide range of known film compositions and structures.

Key steps in the research include using multiple samples of each flexible packaging structure. The NIR spectral data and the material classification were recorded as they passed through a commercial NIR sorting unit.

For samples containing more than one material, NIR spectrums were reviewed for additional spectral information that could point to the presence of minority components besides the primary polymer and allow for a dedicated multi-material classification.

For example, the classification of a film structure as a combination of PET or PA and PE. Such multi-material classification is already in use for beverage cartons, which exhibit a combination of the spectra of paper and PE.

NIR developments
CEFLEX’s research is not the first industry dive into NIR’s potential as a sorting technology for recycling streams. This year, chemical giant Laxness highlighted its use of NIR to identify black plastics efficiently and cost-effectively in sortation devices.

Last month, Ampacet expanded its NIR-detectable masterbatch for black plastic to flexible applications. The carbon-free Rec-NIR-Black masterbatch range is NIR transparent, allowing it to be sorted by NIR optical sensors and then recycled.

By Louis Gore-Langton

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