Muttenz, June 18, 2020 – Clariant continues to develop new technology to improve the recyclability of plastics while offering packaging and product developers more color options. The latest development is a range of deep, dark colors 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 centers.

However, the new Clariant color concepts, developed in its ColorWorks design and technology center near Milan in Italy, now makes it possible to explore a darker and more mysterious color 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.

In most automatic sortation systems, infrared light is beamed onto plastic materials and, because different polymers reflect that light differently, the system can sort the different materials. Unfortunately, the carbon black pigments typically used to make black and other deeply dark colors absorb all or most of the NIR light shone at them and, as a result, the sensors cannot even “see” the black packaging, much less sort one polymer from another.

Late 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, a Norwegian company that is a leader in the field of instrumentation for recycling solutions.
 

To address this issue, the ColorWorks team undertook a project, to use CESA-IR technology to develop colors that could be dark without the use of carbon black. Three colors – a dark umber, a deep velvety green, and a regal dark blue – have been created initially. All three are really saturated so they are almost black but the colors come through, bringing to mind elegance, exclusivity, heritage and boldness.
 

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.