Fluorescent markers could transform plastic recycling

A raft of powerful bodies, including the European Union, are continually exploring how best to reduce or eliminate the amount of plastic packaging sent to landfills. Ambitious targets have been set.

In 2018 the American food company Kraft Heinz announced its aim to make 100% of its packaging recyclable, reusable or compostable by 2025. Earlier, in 2016, the American Chemical Council’s Plastics Division announced targets of 100% of plastic packaging being recyclable or recoverable by 2030 and 100 percent of plastics packaging being reused, recycled or recovered by 2040.

It has been four years since the Plastics Trade Association launched its Zero Net Waste program, which recognizes plastic companies that take steps to reduce net waste in manufacturing.

And now here we are in 2020, closer than ever to these target dates. Yet we are still some distance from achieving our ambitious goals, other than creating an increased demand for recycled materials in packaging. To date, the key hurdle to boosting the amount of recycled plastic for food packaging has been the absence of an automated method for sorting and separating mixed plastic waste such as PET, HDPE and PP based on prior food contact.

Current technologies don’t enable recyclers to shift beyond sorting plastic by polymer type. Identifying what the product once contained has been a near-impossible task and with no effective way to differentiate between a bleach bottle and a milk bottle of the same polymer type, the plastic waste sector has suffered from a severe lack of value creation and therefore investment. The European Plastics Converters Association (EuPC) reported that almost 60% of the European plastics converting companies find it hard to get a supply of recycled plastics materials that meet their quality standards.

Food-grade plastic has been the most complex to obtain due to the risks of using second-hand plastics containing toxic chemicals that are potentially dangerous to human health. According to a 2019 report by the European Commission, of the 27.1 million tons of plastic waste collected in Europe in 2016, only 31.1% went to recycling facilities. The rest went to incinerators or landfills.

But things are about to change, with the launch of an innovative identification technology poised to separate plastic to food grade quality in one single step, thereby radically transforming the sorting process in recycling facilities.

A British consortium (whose partners include, Nextek, R&D Brunel University London, CCL Labels, Enlightened Lamp Recycling, Johnson Matthey, Mirage Inks, Tomra Sorting and WRAP UK) has developed a technology that can rapidly and efficiently distinguish between food-grade and non food-grade polymers. It can identify black plastics and tag full-length shrink-sleeves.

Plastic Packaging Recycling using Intelligent Separation technologies for Materials (PRISM) applies high-performing luminescent materials to labels on plastic packaging, creating what is best described as an invisible barcode for plastics recycling. The process is simple. Fluorescent markers are printed on labels or plastic packaging sleeves.

As mixed plastic waste runs along the conveyor belt the high-speed sorting system is triggered by an ultraviolet (UV) light source that identifies the coded PRISM label, reads its code and air-propels it into the appropriate recycling stream. Following extensive trials, PRISM is now well proven in MRF (Materials Recovery Facility) setups and is plug & play ready.

It is complementary to existing NIR (near infrared) technology and can easily be adapted to most sorting facilities around the world to target specific recycling streams such as food contact plastic packaging. The innovative technology uses traditional labelling and branding methods and is designed to identify a host of different materials applying multiple markers for a wide range of codes. These markers can be removed during recycling leaving no traces for the next cycle of use.

Even the most challenging plastic waste can now be sorted in a single step to over 96% purity with a yield in excess of 95%, which meets the EU’s stipulated 95% purity for PET food grade plastic. This is a significant step forward in the sub-categorization of plastics which are sorted automatically at high speed. It also opens up a wealth of new opportunities for brand-owners wishing to recover their packaging as part of the circular economy.

PRISM is set to provide a much needed impetus towards meeting ambitious targets to both minimize waste and reduce the use of virgin plastic. It will serve as a much-needed boost to the struggling recycling sector.