The main advantage of plastic is its great versatility, and the fact that it can be produced so cheaply. However, its disadvantage is that, once it has been used, it is very difficult to recycle because there are so many different types. And that is currently a major problem with multi-layered packaging used for foodstuffs. This is because, in many cases, it consists of different types of plastic. The big question now is how to make all this plastic packaging recyclable.
People buying food need absolute certainty that its shelf life is guaranteed. Packaging, too, is subject to very strict requirements. Which is perfectly understandable. It does mean, though, that the plastic packaging used for foodstuffs often consists of multiple types of plastic. This benefits shelf life and helps ensure that food is safe. And that in turn reduces the amount of food that goes to waste. On the other hand, it is not such good news for the environment. After all, just try recycling plastic packaging...
Multi-layered plastic packaging
It so happens that the people at TNO relish a challenge. This was evident during PACK-CE, a project carried out for the Dutch Research Agenda. In close collaboration with the Dow chemical company, Hill’s Pet Nutrition, the National Institute for Public Health and the Environment, and a number of universities, various TNO researchers threw themselves into solving the problems in processing multi-layered plastic packaging. “During small-scale laboratory tests, they attempted to separate polymers by using solvents that dissolved one polymer but not the other,” explains Esther Zondervan-Van den Beuken. She is the circular plastics programme manager at TNO.
“We have succeeded in separating various types of polymer from each other. And the process is neither costly nor time-consuming”
Separating different types of polymer
“In tests using one hundred grams of plastic packaging, the dissolving technique appeared to work very well,” she continues. “What that means is that we have succeeded in separating various types of polymer from each other. And the process is neither costly nor time-consuming. Very promising, in other words. But there’s still a long way to go. There are some types of polymer that cannot be separated from others. And we still have to scale up the technology. We would also like to extract the other substances from the polymers, such as pigments and those that make the plastic stronger.”
Recycling without solvents
But would it not be a good idea to make multi-layered plastic packaging in such a way that it could be easily recycled without the use of solvents? This was the second method to be looked at during the PACK-CE project. For two years, the Dow chemical company carried out experiments on packaging foil which, although consisting of multiple layers and having different properties, were nonetheless made of the same type of polymer.
“We could currently use the new plastic foil on around a quarter of products”
New plastic packaging ready to use now
“Multi-layered foil of the same type of polymer can already be used for many purposes,” says Jaap den Doelder, a researcher at Dow Terneuzen. “However, it does allow slightly more oxygen to pass through. This makes it less suitable for example for products that are subject to strict food regulations with a shelf life of several years.”
“We estimate that we could currently use the new plastic foil on around a quarter of products. This could be as much as fifty percent in the foreseeable future. For the remaining quarter, we believe it would be very difficult. The question now is whether this is something we accept, or whether we embark on a mission to find alternative packaging materials.”
“If you don’t start using recyclable packaging now, it really will be too late”
Meanwhile, market demand for recyclable packaging is growing. “If you don’t start using recyclable packaging now, it really will be too late,” emphasises Rolf van Sprang. He is the European Design and Packaging Manager at Hill’s Pet Nutrition, one of the companies taking part in PACK-CE. “Our focus is very much on developing packaging that is fully recyclable. Obviously, the packaging has to continue to give our products the best-possible protection - from storage and transport all the way to the end-user. We made some good progress during PACK-CE, but there’s still a long way to go.”
Design for recycling
“It will probably be a combination,” believes Mark Roelands, Senior Process Technology Scientist at TNO. “That means using recyclable monoplastic foil wherever possible. This is a challenge for everyone involved with ‘design for recycling’. And otherwise, using the physical recycling dissolution-based method. In the meantime, we are also exploring other avenues. These include thermal conversion of packaging plastics. They will then become the raw material for crackers, for the production of new polymers.”
“Recyclable plastic is an important priority for TNO,” he concludes. “That is why colleagues throughout our organisation are currently working on solutions that are both practically and economically feasible.”
Care to learn more about TNO’s research into new recycling methods for plastic foil?
Please contact Esther Zondervan-Van den Beuken