Black plastic packaging is an exceptional product that has a significant end-of-life problem. Until very recently, black plastics couldn’t be detected with the available Near Infrared (NIR) technology.
STADLER
Enrico Siewert
The carbon black absorbs the light, so the signal doesn’t bounce back and the sensor therefore doesn’t get a reading. Black plastic thus makes up a significant part of household waste which, if not recovered, will be incinerated or sent to landfill. If recycling companies can’t recover black plastics, they can be losing as much as 15 per cent of the value of their inbound material, according to Enrico Siewert, Director of Product and Market Development at STADLER, who said: “When they are able to mine this material out of the waste stream, they can create economic value and positively impact their bottom line.”
If post-consumer packaging is not rigorously sorted by colour, the resulting output is a grey resin, so many converters add carbon black to obtain a more appealing colour. “We, as a society, want more recycled content,” Siewert added. “We will see more and more black material in the waste stream. Consequently, packaging will continue to trend towards a darker colour.”
A game-changing technological development
Different industries involved in the plastics value chain have been researching solutions to the black plastics issue. There are now multiple ways of recovering these materials, including a sensor-based dry sorting system, which uses NIR sensors with detectable black additives to detect the different types of polymers. There are now also sensors capable of sorting black materials by polymer. With this sensor-based dry sorting system, it is possible to accurately sort black polyethylene, polypropylene, PET and polystyrene.
A third solution involves a wet density sorting system based on the flotation principle. The lighter polyethylene and polypropylene float, while the heavier PET, PVC and polystyrene sink. However, it is costly due to the filtration process, water use, and cleaning. Furthermore, it is not capable of sorting by polymer, so that a circular process is impossible.
The biggest advancement has been in sensor technology, which is important because the ejected all black materials could be a mix of numerous different polymers, which cannot easily be remanufactured.
The ‘game-changer’, according to Siewert, is the development of sensor technology that creates economic value and makes it possible to recycle these materials.
New opportunities for contributing to a circular economy
The ability to detect black plastics means that there will be more of them in the recycling chain. Demand for post-consumer black materials, must be created and scaled up – although they can’t be used to produce white products, and they can’t always make food-grade packaging. “We have to collaborate across the industry value chain to find other ways to use black plastics,” Siewert added.” It won’t necessarily be for consumer-facing products, but they could be used to manufacture items such as pallets, buckets or railroad ties, etc. It’s about sorting the plastic effectively and providing it as a feedstock to the advanced recycling sector.”
STADLER
Various clean plastic containers for take away or delivery food
STADLER lauds chemical recycling companies as an example of operations that could make good use of these materials since black PE is broken down into a gas and converted into oil, which is then transformed into virgin plastic and thus closing the loop.
It is also important, Siewert added, to extend this cross-industry collaboration to packaging designers and producers. Does the consumer really need or want black packaging? If the material can’t be recovered, what matters the most to the consumer? Do they want a closed loop solution for packaging and do they really care more about how it looks?
Such discussions address the black plastic problem and yield an improved recovery of the waste stream.”
The latest technological developments and the consumer pressure for more recycled content in packaging are driving continued growth in demand for sorting plants capable of recovering all black plastics from the waste stream.
STADLER has reported a sharp increase in interest in these solutions, as Siewert empasised: “We now have multiple partners that have developed technology to detect black plastics, so we have the ability to design systems to recover these materials tailored to our individual customers’ operational requirements and capital investment. We have completed several projects for some of the most advanced light packaging recycling plants in Europe, and we are working to develop many more.”
Demand for this technology is strong and set to continue, Siewert concluded. More black plastic is going into the waste stream and the technology to mine these materials is catching up.