Back to black: Unilever pioneers circular solution for undetectable black plastic bottles

21 May 2019 --- Unilever has developed a new detectable black pigment for its High-Density Polyethylene (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.

The new detectable bottles will be phased in during 2019 and will allow Unilever to further “close the loop” by including the recycled black plastic back in new packaging. In 2019, TRESemmé and Lynx will both introduce a minimum of 30 percent recycled material into their packs.

Currently, “standard” black plastic bottles go undetected by the automatic optical sorting machines in recycling plants because they use near infra-red (NIR) light, which is absorbed by the “carbon black” pigment traditionally used to color them. This effectively makes them invisible to the sorter and leads to them being rejected and sent to landfill.

Unilever has carried out extensive trials, in partnership with NGO RECOUP and waste management partners Veolia, SUEZ, Viridor and TOMRA, which have proven that this new pigment can be technically detected within their material recycling facilities in the UK.

“The black pigment has been available for some time,” Richard Kirkman, Chief Technology and Innovation Officer at Veolia UK & Ireland, tells PackagingInsights. “The differentiation was to modify the site technology but also to get alignment across manufacturers, retailers, waste companies, consumers and local authorities who all need to collaborate for this to work. That’s started to happen – with this being the catalyst – under the auspices of the Plastics Pact.”

“We have deployed an innovative solution within the software and invested in our sorting technology at our flagship recycling facility in Southwark and this, together with Unilever modifying the pigment in the black dye for their HDPE packaging, enables it to be successfully detected. If all recyclers and manufacturers follow, this means black plastic becomes detectable black.”

“Adjusting the detection mechanism in this way, with both technology and packaging modified was the key. It’s the first time a hi-tech solution like this has been applied to black plastics and can be rolled out at scale – a eureka moment for recycling and a rallying call for similar partnerships to take shape,” he adds.

Kirkman believes that one challenge will be communicating the enhanced sustainability credentials of the new black bottles to the consumer. This is especially challenging given the continuing rise in anti-plastic sentiment that is felt most fervently towards the previously unrecyclable black plastics.

“As with all recycling, it’s a communications challenge. We have to work on effectively communicating change in these new solutions through careful labeling to help consumers. Labels are a busy place for information and this adds to that space so we need to look to communicate this clearly,” he says.

This move to using the new detectable black plastic is part of Unilever UK’s commitment to The UK Plastics Pact and its new “Get Plastic Wise” campaign, a Five Point Plastics Plan which aims to tackle plastic waste in the UK and move towards a closed loop where plastic stays within the plastic economy, not the environment.

“Tackling plastic waste is complex and involves collaboration across the supply chain. We welcome this move by Unilever and steps taken by waste management companies to trial the sorting of the packaging. We now call for wide-scale adoption of detectable black pigments by brands and retailers, and the sorting and reprocessing of that packaging by the recycling sector,” says Helen Bird, Strategic Engagement Manager at WRAP, which manages The UK Plastics Pact.

“Through the commitment and leadership of Unilever, and with the support of the resource management industry, this is a fantastic example of how detectable pigments can be used to improve plastic packaging sortability and recyclability and shows what can be achieved through practical partnerships and real cross supply chain collaboration,” adds Stuart Foster, CEO of RECOUP.

“Unsortable plastics, particularly the traditional carbon black packaging, has been one of the key interest areas for media, consumers and politicians in recent years. The sharing of data, knowledge and solutions was the focus of the RECOUP led Black Plastic Packaging Recycling Forum, and we encourage all manufacturers, brands and retailers to follow the leadership of companies, such as Unilever, and ensure that plastic packaging placed on the market can be recycled,” Foster notes.

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.

Initiatives to combat the recycling challenges that black plastics present are becoming more prevalent. In June 2018, UK packaging supplier Faerch Plast announced that it was working collaboratively with Marks & Spencer, Tesco and Sainsbury’s and leading UK waste reprocessor Viridor to convert recycled black plastic into new food grade packaging. The company claims that the project has seen 120 tons of black plastic (eight million items) recycled each month since July.

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.

By Joshua Poole