Concerns surround additives' PET recycling impact

By Paul Gander

- Last updated on GMT

Related tags: Recycled polyethylene terephthalate, Polyethylene terephthalate

Concerns surround additives' PET recycling impact
As ministers consider a significant increase in the recycling target for plastics, the role of additives in compromising the single most successful stream of post-consumer recyclate (PCR) is becoming clearer.

According to experts, oxygen scavengers, acetaldehyde scavengers, ultraviolet (UV) blockers and other blended (as opposed to multilayer) additives are undermining the quality of recycled polyethylene terephthalate (PET).

"Designers of bottles know what current technology can do,"​ said Ed Kosior of Nextek Consulting. Those technologies include a wider range of barrier blends, with greater cost competition in the marketplace. "The problem is that these designers tend to have no built-in cross-check mechanism for establishing whether their ideas will have an impact on recycling."

Lower quality product

Importantly, while multilayer barrier including nylon layers sandwiched in PET can largely be separated out by the sorting and cleaning process, this is not the case with blended additives. The end result can be a lower-quality product which is not suitable for the full range of applications.

Kosior explained: "Those effects generally take the form of discoloration. But there can be other impacts, including migration."

Jonathan Short, md of Lincolnshire-based recycler ECO Plastics, agreed: "You see it mostly in the colour: a pale grey haze, which is generally put down to additives."

In terms of price impacts, this can mean that the resulting food-grade PCR is not competitive with virgin PET. It can also mean, according to ECO Plastics, that with a smaller proportion of output hitting the highest quality standards, it ends up being more expensive.

Short cited the ActivSeal oxygen scavenger system from ColorMatrix (with APPE formerly Artenius PET Packaging Europe now as the exclusive European licensee) as an example of a "very efficient way of minimising contaminants in recycling"​. According to APPE, the system combines "a minute amount"​ of the catalyst in the container wall with a hydrogen activator built in the closure.

Recycling friendly

"If ColorMatrix can do this, why can't there be 'recycling-friendly' UV blockers, for instance?"​ he asked. "I expect it's to do with the cost."

Another concern is that, as converters and brands lightweight their bottles, there is an increased temptation to compensate for thinner walls with more additives.

But not everyone sees this as a major challenge. Chris Dow, md of the Closed Loop London recycling business, said: "The increase in additives in PET is likely to have a more profound impact on recycling in the future, which is something we are aware of and are looking into now, in order to minimise their impact in future."

For many recyclers, a straightforward increase in bottle collection rates would come higher up their list of priorities. Dow is among those advocating the adoption of 57% plastics recycling targets, as proposed in the Department for Environment, Food and Rural Affairs' consultation on waste. "The higher targets will allow us to grow the industry and become a major economic driver of the future,"​ he said.

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