Materials design strategies for end-of-life processing
Tony Gaukroger, Director, Colour Tone explains how an innovative near-infrared colourant can address end-of-life product processing concerns.
The Design Council recently estimated that ‘80% of the cost of a product is set at the design stage and therefore, reducing the environmental impact of any product during the concept design is the most beneficial stage at which to make cost savings’.
This thought process can now be applied when specifying ‘next generation’ colourants for the design of products and packaging. By adopting this innovative technology, designers can not only achieve good design through the right colour choices and ensure legal compliancy – they can satisfy end-of-life (EOL) concerns for the first time too.
But why should this be a key consideration?
Increases in product disposal rates and the speed of technology development are constantly creating new challenges. It is becoming ever more important to evaluate the impact of products at their EOL. Product designers require better information to aid their decision making up front on the materials they specify.
Manufacturers have long been looking for a way of quantifying sustainability and as a result Life-Cycle Analysis (LCA) or carbon footprinting have become commonplace. These approaches have been adopted to identify the environmental impact of a company.
End-of-life considerations
In recent years the EU has issued directives about end-of-life vehicles, restrictions on the use of hazardous substances and electrical products and equipment all of which force manufacturers to respect these concerns.
Products need to be designed therefore, to reduce the amount of waste going to landfill, favouring closed loop scenarios where materials can be recovered and as a consequence, the use of virgin material is reduced.
Specifying colour is one of the most powerful tools in the product designer’s armoury, for the first time EOL considerations can impact this process too. As a specialist colourant and masterbatch supplier to the plastics industry, Colour Tone supports the technical needs of a broad range of end users. It is therefore, ideally positioned to monitor the changes both in colour trends and strategic environmental and cost concerns in the marketplace.
In recent years the role of the masterbatch manufacturer has changed, instead of simply matching a colour, the industry is often required to enhance the physical properties of the product at the same time to deliver for example, enhanced UV protection, flame retardance or antistatic qualities. Colour Tone has now taken this a stage further by developing the technology to allow its colourants to be detected by near infrared sorting systems for EOL processing, why?
Near-infrared (NIR) technology for black food tray recycling
Each year 1.3 billion black food trays are sent to landfill as black and other dark coloured packaging cannot be picked up by recycling sorters. This is because these packaging products contain carbon black that reflects very little or no radiation rendering it ‘invisible’ to sorting machines in recycling depots.
In response WRAP commissioned a project, ‘Development of NIR Detectable Black Plastic Packaging’ supported by Colour Tone and plastics resource consultancy Nextek. The aim was to develop a solution to enable black plastic packaging that is currently destined for landfill or energy recovery, to be recycled.
A new NIR black product was developed as a result, to reproduce as near as possible the same shade and opacity of carbon black (previous attempts had resulted in a less commercial brown), while still being detectable by sorters. This approach using novel NIR detectable black colourants and was shown to work with APET, CPET, PP, HDPE, PS, and PVC in both laboratory and large-scale trials at a plastic recycling facility.
This initial trial proved that the technology would work in principle, but further research was required for wider adoption by the supply chain.
Next stage research
Having achieved its original aim by devising black masterbatches to suit numerous end applications in different polymers using NIR black. This time Colour Tone’s focus was to determine how well this technology can be applied to a broader range of colours including, dark blue, grey, brown and many others used for food trays and other applications.
The colours were chosen from existing matches to give a good selection of shades and included greys (light, mid and dark). A spread of concentrations of carbon black in the original formulations was used to compare their detection abilities against the performance of the new NIR formulations.
The tests analysed solar reflectance and heat build up [HBU], once again, in each case the reflection was higher than in previous trials confirming that the substitution of carbon black by an NIR black delivered a significant measureable difference across a range of colours.
Tony Gaukroger continues: “We are therefore confident of being able to replace carbon black with NIR black in any colour to improve its suitability for sorting by NIR spectroscopy and that this doesn’t necessarily lead to a dramatic increase in the cost of the formulation either.
“When selecting pigments to achieve a set colour criteria however, we are also mindful that it isn’t just carbon black alone that absorbs infra-red, other pigments can absorb it too. So we will always look for Infra Red Reflective [IRR] pigments to help provide a wider palette of colour options, but still delivering optimal colour performance to the end product.
“At Colour Tone we are therefore always ready to offer the most creative and innovative new products. Our on-going research and development is the basis for our high quality masterbatches, as we continually look to improve not only their composition, but also our production technology and test methods to deliver market leading results.”
Conclusion
The entire life-cycle of the product should therefore be considered when looking at improving product design. This novel NIR technology has the potential to also be applied to any number of applications from food trays to auto components and cosmetic packaging, enabling manufacturers to get closer to meeting life cycle analysis goals.
Tony Gaukroger, continues: “Using IRR pigments as part of the colour specification would not present an issue for product designers. For most colours the cost penalty would be minimal, just 0.05 pence per food tray for example. It would lend the product an additional marketing advantage too by demonstrating that the supplier is environmentally responsible.”