Clariant has developed a range of deep, dark colours that normally would have required the use of carbon black pigments that makes them undetectable by the near-infrared (NIR) sensors used in automated polymer sorting systems at recycling centres.
The new Clariant colour concepts, developed in its ColorWorks design and technology centre near Milan in Italy, now makes it possible to explore a darker colour space entirely without the use of carbon black.
Development is progressing in polyester (PET), high-density polyethylene (HDPE) and polypropylene (PP) in both virgin and post-consumer recycled (PCR) forms.
Clariant
Last year, Clariant introduced CESA IR, a masterbatch range that makes black plastics visible to NIR radiation. This effect was confirmed by testing conducted by TOMRA Sorting Recycling.
Roberto Romanin, a ColorWorks Designer at Clariant, said: “There are very definite trends in this direction. Some exclusive, high-end facial treatments, nutrient serums and oils are being packaged in these rich dark colours. However, most of them still use carbon black and so they have recyclability problems.”
To address this issue, the ColorWorks team undertook a project, to use CESA-IR technology to develop colours that could be dark without the use of carbon black.
Three colours, a dark umber, a deep velvety green, and a regal dark blue, have been created initially.
Mirco Groeseling, Regional Circular Economy and Sustainability Manager EMEA at Clariant, explained: “Until now making dark and black plastics NIR detectable required that the amount of carbon black must be carefully controlled, and this is not always possible under real-world conditions. So, we have been seeking – and we have found --new solutions that are very black, and we have been able to remove carbon black totally from these new detectable formulations.”
Clariant says the range is suitable for all major packaging polymers including PET, polyethylene and polypropylene (including post-consumer recycled resin) in all the various packaging applications, including trays, bottles and caps.