Looking into the future: clear PET's rise and coloured plastic's decline
From milk tops to Sprite bottles, coloured plastics have a grey future, whilst the value of clear PET is becoming transparent.
A trend used to be an overall move away from coloured plastic and towards clearer PET. Credit: Chanishka Colombage via Shutterstock
With only 9% of plastic successfully recycled globally, there has been a growing push towards a circular plastic economy: a closed-loop system for recycling materials which eliminates waste and reduces the need for new production.
Through the 2022 Global Commitment, made in collaboration with the UN Environment Programme, and the Plastics Pact Network, over 1,000 businesses and governments have already enacted plans to move towards a circular economy, committing to a variety of 2025 targets, which include ensuring that 100% of plastic packaging is reusable, recyclable, or compostable.
Dominic Cakebread, GlobalData analyst, commented that: “Almost all of the major global companies in the packaging supply chain – from retailers, CPG manufacturers, packaging converters and polymer suppliers are fully aware of the need to move to a circular economy and have sustainability policies, targets and systems in place to address this.”
However, not all plastics are created equal. There are seven types of plastic (marked with different codes to indicate recyclability):
Commonly recycled are:
1- Polyethylene Terephthalate (PET) – bottles, textiles
2- High Density Polyethylene (HDPE) – bottles, cartons
5- Polypropylene (PP) – yogurt pots, bottle caps
Less commonly recycled:
3- Polyvinyl Chloride (PVC) – piping, cables and cladding
4- Low Density Polyethylene (LDPE) – plastic bags
6- Polystyrene (PS) – plastic cutlery
Clear PET's role in recycling and the circular economy
Fortunately, Polyethylene Terephthalate (PET) is the most commonly used plastic across the packaging industry, as well as textiles and other verticals. Marked with a number 1 recycling code, it is also the most widely recycled and – as the market for recycled plastic grows – it is also the most valuable.
Waste management company Biffa told GlobalData that it recycles about 190,000 tonnes of plastic annually, of which 80,000 tonnes is PET. The other 110,000 tonnes is comprised of HDPE (including 69,000 tonnes per year of milk bottles) and PP.
Recycling facilities shred and extrude waste before sorting clear and coloured PET pellets through optical scanners. These use near infrared (NIR) scanners to measure the absorbencies of materials at specific wavelengths, thus distinguishing between colours and separating them accordingly.
These separated pellets or flakes can then be melted into new material that can be shaped according to its intended purpose.
However, dyed plastics create issues. Kelsey Traynor, representative of Biffa, explained: “clear PET is more valuable because, when it is recycled, it can be used more widely in packaging. Unfortunately, if coloured PET gets mixed in with clear the whole mix becomes a ‘dirty grey’ colour which manufacturers and brands do not want to use for their products.
“Food grade PET sells for around twice the price of non-food grade – it is higher quality and is desired by brands for their circular agenda.”
Coloured PET challenges and sorting technology innovations
White PET is often a particular contributor to the ‘dirty grey’ problem, as opaque plastic is a popular colour in packaging because of its preservative qualities. White plastic can protect light-sensitive flavours and vitamins from degradation caused by exposure to UV light; however, sorting technologies often struggle to distinguish between transparent and opaque PET. Mixed recycling results in the less-transparent product, which is consequentially less valuable to the recycled packaging industry.
Black PET also used to present a particular headache for sorting technology in recycling plants. Coloured using carbon black pigments, the PET absorbed the near-infrared part of the spectrum, making it invisible to sorting machinery.
However, new technologies are driving change. In September 2023, Steinert and RE Plano, a subsidiary of the Remondis Group, announced that they had successfully completed an AI-based sorting facility in Bochum. The Intelligent Object.Identifier combines a colour sensor and NIR sensor with hyperspectral imaging (HSI) technology to filter PE and PP plastic by material and colour.
In July 2023, Japanese technology giant Canon announced it would be releasing new sorting equipment, which would use Raman spectroscopy to identify even different shades of black plastic quickly and accurately.
Commitments from companies have also successfully implemented change: the UK Plastics Pact required members of the Waste Resources Action Plan (WRAP) to use detectable colour pigments by the end of 2019, and required waste management companies sort black PET for recycling.
The solution now appears to be an overall move away from coloured plastic and towards more clear PET. Traynor said: “Ideally, we need to eliminate all colours in food grade packaging to make it easier and more cost effective to recycle.”
This is a tactic already adopted in Japan, where all bottles are produced using clear PET to enable a circular economy, allowing the plastic to be repurposed and reused whilst maintaining value. Japan ranked second globally according to the plastic management index (PMI) and was among the top countries for management of PET bottles, with a collection rate of 93% and a recycling rate of 85.5% (as of 2019).
Supermarkets and brands embrace clear plastic, yet circular economy challenges persist
Supermarkets in the UK are also moving towards clear plastic: ASDA announced in August 2023 that it would replace coloured milk tops with clear plastic, which it claimed would enable 268 tonnes of High-Density Polythene (rHDPE) to be recycled back into food-grade packaging annually. It followed Waitrose, Tesco, One Stop and Co-op in the move.
Coca-Cola has also moved towards clear PET, swapping the iconic green Sprite bottle for a clear design in order to enable easy recycling. The bottles can now be made into Coca-Cola trademark brands use rPET bottles.
However, clear PET is not the only solution to plastic recycling. Speaking specifically on the UK, Traynor said: “It would also be helpful to make the packaging tax progressive to incentivise the use of recycled content beyond 30% as well as introducing deposit return schemes to improve collections and reduce contamination of the recycle streams.”
She is referring to the Plastic Packaging Tax in the UK, which charges £210.82 per metric tonne of plastic packaging where the plastic used is less than 30% recycled. Certainly, incentives for companies to transition to a circular plastic economy seem to be part of the solution.
Cakebread offers other suggestions: “[A true circular plastic economy] is probably only technically feasible via large scale depolymerisation / pyrolysis (returning the plastics to their base polymers) as nearly all recycling of packaging materials involved some degradation of the quality of the post-consumer waste materials.
“Closed loop collection and DRS system can help improve the quality of and standardise the recycled materials, however in practice much of plastics packaging the is currently recycled is not used in the original applications (as bottles) and even when it is, these do not last more than a few return trips. This is not therefore a perfect circular economy.”