Back to black: Clariant’s new technology boosts recyclability of black-colored plastics

26 Aug 2019 --- Color and additive concentrates for plastics company Clariant’s new CESA-IR additive masterbatches make dark-colored plastics visible to the near-infrared (NIR) sensors used in automated polymer sorting systems. While many companies use black packaging to brand prestige products, it can pose problems to recycling systems and has led to calls for black to be phased out of the palette. Clariant’s new masterbatches help to resolve this issue and allow for increased recycling rates in Europe and further afield.

In most automatic sortation systems, infrared light is beamed onto packaging materials. In this process, different polymers reflect the light differently, so NIR sensors can discriminate between high-density polyethylene, low-density polyethylene, polypropylene, polyester and various other commonly used polymers in today’s packaging. However, the carbon black pigments typically used to make black plastics absorb all or most of the NIR light. As a result, the sorting sensors cannot “see” the black packaging and cannot sort one polymer from another.

Initiatives to combat the recycling challenges that black plastics present are becoming more prevalent.“As a result of this phenomenon much of the dark-colored materials entering the recycling stream has not been recovered,” explains Alessandro Dulli, Clariant Masterbatches Global Head of Packaging. “For that reason, many brand owners have been pressured to move away from black for environmental reasons. In close collaboration with these brand companies and as an expertin sortation technology, Clariant has developed a way to achieve a persuasive black color in plastics without compromising the essential detectability during the recycling process.”

Specific CESA-IR formulations have been developed to enable IR-detectability of black High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE) in injection and extrusion blow-molded products; black polypropylene (PP) in films and injection-molded products; and black PET and C-PET in sheets and film.

Back to black
Initiatives to combat the recycling challenges that black plastics present are becoming more prevalent. In May, Unilever developed a new detectable black pigment for its HDPE bottles that enables them to be sorted by plant scanners and recycled. The new bottles will roll out this year for the TRESemmé and Lynx brands.

The consumer goods giant claims that this will enable 2,500 tons of plastic bottles to be sorted and sent for recycling each year – the equivalent to the weight of 200 London buses. The solution comes as part of Unilever UK & Ireland’s new “Get Plastic Wise Campaign” and will reportedly be shared with other manufacturers. 

Also on the black plastics sustainability trail, German chemical and consumer goods company Henkel is set to launch a fully recyclable black plastic bottle for its Bref products. The new packaging material – developed by specialist plastic supplier Ampacet – uses an alternative carbon-free black color, enabling used bottles to be detected by recycling facility NIR optical sensors and integrated back into the value chain. 

Similarly, Procter & Gamble (P&G) has been experimenting with watermarking technology, which is designed to add efficiency and precision to the sorting process of difficult-to-recycle materials such as opaque and black plastics. Watermark technologies have been developed by partner companies Digimarc and FiliGrade. 

Edited by Laxmi Haigh