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Development and Market Replication of novel NIR-transparent polymer colourants to replace carbon black, and allow the sorting of black and coloured polymers from mixed waste streams

Periodic Reporting for period 2 - NIRSort (Development and Market Replication of novel NIR-transparent polymer colourants to replace carbon black, and allow the sorting of black and coloured polymers from mixed waste streams)

Reporting period: 2018-06-01 to 2019-05-31

This aims are to replace carbon black and many other pigments with near-infrared (NIR) detectable options for adoption by Europe’s packaging, automotive and consumer durables manufacturers. Each year 3.5MT of polymer are scrapped in the UK alone, as black and some other coloured packaging cannot be picked up by recycling sorters. As these products contain carbon black that reflects very little or no radiation rendering it ‘invisible’ to sorting machines in recycling depots. Black plastics alone represent around five per cent of packaging (one million tonnes) and 30 per cent of WEEE and vehicle polymers (2M Ton), none of which can be recycled. A further million tonnes of coloured waste containing carbon black is also lost to landfill or incineration in the UK yearly. We aim to develop a range of colours for polymers that will enable NIR sorting operations to segregate black and coloured plastics from waste streams to a level of purity that they are useable in highly engineered polymers. The consortium have defined a programme of development, designed to identify formulations with optimal cost effectiveness in packaging recycling and to extend the technology across to WEEE and end-of-life vehicle applications, each of which has its own specialist requirements. The most immediate need is food packaging. While waste from consumer durables goods has a mean-life of five years and ‘end-of-life’ automotive vehicles13 years, both require solutions to prevent the continued build-up of potentially unrecoverable polymers.
We have selected 5 potential case study parts. We aim to produce these parts in up to 3 different polymers combined with our new NIR readable pigment technology. The selection was targeting current production components on a single cavity tool that can be use with a wide range of material with different melt flow and shrink rate. The same material, once tested and validated, can be used in other parts more complicated and/or produce on a multiple cavities tool. The case study parts which have been selected represent a good cross section of sectors, applications and material types. These are produced in high volume and at present are not recycled because they use conventional black pigments that are not NIR sortable due to the presence of Carbon Black. We will test these new NIR readable compounds using a range of mechanical, electrical, thermal, aesthetic, optical and rheological test methods to determine their suitability to replace conventional compounds. We will test their suitability for NIR sorting by running parts down an NIR sorting line, assessing the throughput and efficacy of NIR sorting lines for each compound.

The information on wavelengths for polymer discrimination is not publicly available, so a process of deduction was required. With this baseline, individual colour components were then introduced and commercially tested for sortability to derive thresholds of detection which were yet further refined as more testing was completed. This fundamentally facilitated the identification of the critical wavelengths for detection. It was identified that we could quantify this threshold and implement a numerical methodology on which to independently test for indicative sortability. The development of this algorithm (SIR) provides a design and development tool which allows us to create bespoke colour formulations (both black and colours) which are both visibly coloured as required AND are created to be infra red sortable through the retention of the polymer reflectance wavelengths in the necessary ‘windows’ of the infra red spectra.To ensure ongoing reference back to commercialisation and cost, the concept of component cost has begun to be captured and considered within all associated developed work in both this and future work-packages, to mitigate the development of a ‘solution’ which is infra red sortable but is not commercially viable.

Following identification of the critical wavelengths and our SIR measurement tool, a library of polymer and individual pigment reflectance’s has begun to be captured.

Having ascertained the wavelengths used in commercial sorting and reflectance characteristics of a plethora of popular pigments, the next step was to focus on deducing the impact of different pigmentation levels/concentrations on NIR sortability, then using this knowledge together with the NIR sortability algorithm developed, to combine appropriate pigments into a range of NIR detectable colour packages.
We can break the key findngs into 2 key themes:
1. The impact of pigment concentrations on infra red reflectance
2. We have been successfully able to formulate a range of NIR detectable colours which are proven as sortable.

We are also confident that these NIR sortable colours have been formulated to be as cost efficient as possible.
Key validations:
• Precise colour pack formulations
• A method for producing the compound
• Testing of opacity to ensure that visibly acceptable opacity levels are achieved.
• Final standards for both colour and infra red reflectance for each of the colours within the NIR sortable range which we have developed.

We have defined our detailed plan for the production of polymer compounds, and our subsequent methodology for the testing of these polymer compounds
Our proposed NIR detectable colour range has been conceptually created in concentrated masterbatch form and they have been moulded into base polymers to create some colour plaques as a representation of the visible colour which is achieved. Masterbatch has then been manufactured and sent to both Polykemi and Luxus who have then compounded this masterbatch for further testing.

These masterbatches have been compounded by Luxus and Polykemi into the following natural compounds manufactured and provided by Polykemi:
• PBT
• ABS
• PP
"The socio-economic impact is potentially huge. For some time the suggestion has been made that the kerbside recycling collection could perhaps be expanded to include other plastics than just packaging. Progress with the project to date would suggest that this proposal could be easily adopted if all plastic items were sortable to the same criteria as plastic packaging. The technology is available and we have proved the theory with the workable examples, although there is further work to be done to gain a full understanding of the process and materials. This understanding is essential if we are going to make disposal at end of life part of the design criteria. It will require fundamental changes in the materials we use for colouring plastics and in methodology but will result in the opportunity to automatically sort all plastic items [consumer or industrial], at the end of their life, back into usable recycled compounds so making plastics truly sustainable and reducing the amount that goes to landfill. Only with comprehensive understanding and proven examples can we expect the change in attitude to encompass ""end of life considerations"" as part of the design criteria. The issue of getting innovation to market is always large. In this area we will be relying on the plastics industry to adopt the new technology and concepts and with legislative and consumer pressure to reduce the amount going to landfill are compelling. The surplus of recycled plastic material entering the market will also produce challenges but we cannot underestimate the financial, commercial and environmental benefits of this.
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