Packaging marker technology may not be ‘the answer’ for recycling

Axion Consulting has said that developments in packaging marker technology should not be viewed as ‘the answer’ to increasing recycling, however, they could be valuable in other ways leading to higher quality and increased value. 

Axion also says that while methods to detect different polymer types, such as fluorescent pigments and digital watermarks, offer exciting potential, they should be seen as a way to safeguard recyclate quality.

Meanwhile, Near Infrared (NIR) technology still has large amounts of ‘unexploited potential’ in recovering more packaging such as PP from rigid plastics, PE and PP films, which would go a long way to increasing recycling rates.

NIR technology detects polymer type, which for many years was sufficient to recover high quality PET, HDPE, LDPE film, and PP, but this is changing thanks to diversification in the plastics market, which is leaving the established infrastructure behind.

Innovation in packaging has led to a more complex waste stream that contains many different components.

An example of this is a shift in UHT milk containers from recyclable HDPE bottles into opaque PET containers has a negative effect on recycling.

The growing use of PET in non-food products can also lead to challenges when using recycled PET in new food packaging.

Richard McKinlay, Head of Engineering and Research at Axion, said: “This shift has brought forward the need for an alternative to NIR that can sort material on more criteria, to protect existing recycling processes and drive up quality to access higher value markets.”

Two new methods are the aforementioned fluorescent pigments and digital watermarks.

Fluorescent pigments are invisible in normal lighting conditions, and can only be detected under UV light.

They are specifically chosen for optimum performance while minimising cost, and are safe for food contact applications.

Digital watermarks are patterns that can be applied in label or packaging design, or directly to the polymer surface.

Having minimal visual impact, they can be detected by a camera and created at a very low cost.

They can also hold a large amount of data, such as material composition, original contents, and suitability for recycling.

Fluorescent pigments are further ahead in development than digital watermarks, with some European projects, such as Polymark, already completed, and others close to completion.

McKinlay said: “There is, therefore, a better understanding of efficacy of fluorescent pigments. There are still many unknowns after watermarking and more independent studies are needed. Watermarking could be a powerful tool in the future because of how much data it can hold, and brand owners can gauge how much of their packaging is recycled.”

An example of this power would be that the same watermark can be used by manufacturers during production, and by consumers to give product information such as nutrition or recipes.

The same information can then be used by the recycler to know where to sort the material for maximum value recovery.

This ability to share data across the value chain has the potential to be a very powerful, but it is only part of the solution, as packaging must still be fundamentally recyclable in an economic way.

MicKinlay concluded: “To me, although this type of technology may be a very powerful tool for information gathering, it is not an answer to increasing recycling rates. In my opinion, this marker technology should be seen as a way to safeguard quality of materials for recycling. In terms of increasing recycling rates, I think it is unlikely it will have any significant impact. The only way to increase recycling rates is to do more sorting on more of the plastic fractions that are currently going to energy recovery because it’s not economically viable to recover them. In order for this to happen, a fundamental change in the economic drivers for recycling is needed.”