INNOVATION | FLEXIBLE PACKAGING
for enhancing the D4ACE guidelines. The report on “Near-infrared classification and sorting test programme” also provides a summary of key outcomes at a generic level. The summary says: “Pristine transparent films below 40μm in thickness were difficult to detect reliably; in many cases, films had to be folded over or stacked to obtain sufficient intensity for reliable detection to be achieved. In operational waste management and sorting facilities, improved detection results are expected due to higher levels of scratching and wrinkling of the packaging plus the presence of dust and product residue; the results presented [in the report] are therefore a ‘worst case’ in terms of obtainable NIR signal intensity.” Other key outcomes in the summary include: “The
Above: Ceflex gained a new level of detail about NIR sorting of flexible packaging types
body of work being undertaken by Ceflex academ- ic partners and test centres in Europe. The pro- gramme will also focus on mechanical recyclability of flexible packaging structures and the impact that packaging size and shape have on sorting. Ceflex said its intention is to generate open-source, robust and independent data to strengthen flexible packaging design guidance across the board. Insights gathered from the test results will be used to enhance its Designing for a Circular Economy (D4ACE) guidelines.
Houlder said: “Designers of flexible packaging now have a new level of detail on exactly how to achieve the best outcomes.” Principal results and data are now available in an open-source report for public download at
https://guidelines.ceflex.eu. Commenting on the report on NIR sortability, Liz
Morrish, Ceflex Design Lead, said: “In addition to establishing exactly how NIR sees packaging structures, the data shows how orientation, layer sequence, and opaque and reflective materials – such as carbon black, metallisation, aluminium, paper – can affect the sorting outcomes and at what thresholds.”
Right: The Design Check online tool allows users to check if a packaging design or specification adheres to recyclability guidelines
Vital data Approximately 100 flexible packaging structures and more than 200 samples were used in the NIR sortability tests, evaluating materials including PE, PP, PET, PA, EVOH, PVDC, metallisation, aluminium foil, inks, coatings, pigments, fillers and copoly- mers. The programme collected a large amount of data on these materials and multi-material-multi- layer (MMML) structures enabling analysis at an unprecedented granular level. Ceflex said that only data and results based on
what is considered the current practice and NIR infrastructure in material recovery facilities, such as MRFs, and sorting centres, in Europe will be used
16 PLASTICS RECYCLING WORLD | January/February 2024
www.plasticsrecyclingworld.com
high reflectivity or high NIR absorptivity of certain samples caused difficulties in detecting plastic films. “Pigmentation, print, and matte surfaces
generally improved the detectability. “The penetration depth of the NIR method was found to be substantially bigger than the most common flexible film thicknesses (for example: above 300μm, as determined from the polyamide/ polypropylene series). Therefore, information from all layers of a flexible packaging structure was returned in the NIR spectrum, except where a reflecting or absorbing layer, such as aluminium foil or paper, blocked out some of the ‘lower’ layers. “MMML structures consequently resulted in NIR
spectra that contained signals of all layers penetrat- ed by the NIR radiation; the laboratories [involved in the testing] believe that many MMML structures could therefore be identified as such if the minority material in the structure comprises at least 20-30% thickness of the overall structure. “The layer sequence or orientation of the films did not impact the obtained NIR spectra, and therefore for the classification, unless a reflecting or absorbing layer, such as aluminium foil or paper,
IMAGE: CEFLEX
IMAGE: CEFLEX
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