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Plastic recycling: behind the scenes

Most plastics are perfectly recyclable. Everybody knows that. However, there are few people who know what it takes to make this possible. That is why we are taking a look behind the scenes of plastic recycling. A unique project where Alligator Plastics and our customer, Lightweight Containers, are working on together: the circular production of one-off plastic casks.

Out of sight of the general public

Plastics have a lot to offer the world, but we have to be sensible about them. A major advantage of most plastics is that they are recyclable, but this is not as easy as many people think. We know that the material must be collected, separated, cleaned, and crushed before it goes back into the machine. However, this is just the tip of the iceberg. “There are many challenges in order to make this process possible. Moreover, these are challenges that almost all take place out of sight of the general public,” says Bas van Reisen, technical director of Alligator Plastics. “We come across all these issues in the Lightweight Containers initiative. It is a great opportunity to show more people what the plastic chain is doing to make the circular economy possible for plastics.”

Making the impossible possible

Lightweight Containers from Den Helder has been a customer of Alligator Plastics since 2006. Together, we developed a plastic cask for carbonated drinks, as a lightweight and flavor-retaining alternative to steel casks. The cask is also called the KeyKeg, and although it is meant for single use, it is very durable. It is made from approximately 30% recycled material and has a circular design, allowing 81% of each KeyKeg to be used to make a new KeyKeg. With the OneCircle initiative, Lightweight Containers wants to make the cask completely circular. To this end, the Dutch company is setting up a worldwide collection and recycling network, so that, within a few years, all KeyKegs are a valuable raw material for new KeyKegs. A completely closed cycle. As the company states: “Where it seems impossible, we make our start.”

Smart design with recyclate

Alligator Plastics produces the injection molded parts of the KeyKeg. The container and other parts are made by other producers using different techniques. The hunt for a circular product starts with design. As Bas states: “That needs to be smart. This means a good product that can be disassembled, with materials that are easy to recycle in a material-saving design. From our expertise, we have achieved these characteristics from the start. We are currently mixing 20% recyclate for the largest injection molded parts of the KeyKeg to the supplier’s regranulate. We will continue to increase this in the coming years. We also look at which other injection molded parts are eligible for admixture with recyclate. We are careful with this because some parts are extra demanding in terms of mechanical properties and product safety.”

The right quality without contamination

Because Lightweight Containers sells its products worldwide, part of the production also takes place at local injection molding companies in order to minimize the environmental impact caused by transport. Based on the same consideration, the company also prefers to do business with collection and recycling companies that are close to customer markets. Lightweight Containers facilitates collectors via OneCircle with, for example, balers and plans to set up their own recycling plants at certain locations in the future – if this is necessary for proper recycling of the KeyKegs. “What happens at the recyclers is crucial for the further success of the cycle,” says Bas. “Ultimately, as a parts manufacturer, we must receive recyclate that has the right quality to make new injection molded parts for the KeyKeg. This means that the material must first be properly separated, so that few types of plastics as possible are mixed together and, of course, few other materials as possible. Contaminants such as metal, glass or other materials with a higher or lower melting temperature can cause all kinds of process disruptions. This can cause damage to products or machines. There are more contaminants that have to be removed from the material through various techniques in order to make the recyclate suitable for reprocessing.”

Inevitable degradation

So far, the recycling process is still fairly straightforward. However, the real challenges the chain faces are still to come. It starts with the inevitable degradation with respect to the virgin material. Bas: “To inject the product components for the KeyKeg, the plastic in a machine must undergo a number of treatments: heating, kneading, mixing and processing under pressure. A lot happens that affect the polymers that make up the plastic. The processing of plastic, therefore, generally has a negative influence on the mechanical end properties of the product. The KeyKeg is then used, undergoing all kinds of influences such as pollution and sunlight. It is then collected and recycled. Ultimately, the intention is that this recyclate goes back into the injection molding machine to make it into a new KeyKeg with virgin material. In the meantime, however, the material has been somewhat degraded, which in turn has an influence on the properties of the mixture of recycled and virgin material to be injection molded.”

Breakthrough in plastic recycling

This degradation process is repeated time and time again, with every recycling cycle. For the time being, virgin material is always necessary in order to not deteriorate too far in quality. Solving this degradation problem is one of the biggest challenges in plastic recycling. At the same time, according to Bas, it is one of the most exciting opportunities to show the innovative power of the sector: “In a laboratory, it is already possible to upgrade the molecular structure of degraded plastic to the quality of virgin material. This has been discovered and realized by the plastics industry of its own accord. The technology is still too expensive at the moment, but it is only a matter of time before we can really do something with it and it can be applied on an industrial scale. Many current plastic-recycling problems could be solved with this. It would be a major step forward, and it would bring quality-equivalent production with 100% recyclate considerably closer.”

Choices in color and standardization

Another big challenge is color. “If a recyclate contains black material, we can no longer make a white product with it and the recyclate becomes darker and darker. The plastics industry has also devised innovative technology for this. Even after grinding, colors can now be separated. The technique is not yet used with recyclers, but it has already been introduced to raw material producers as part of quality assurance in the production of virgin granulates. In the future, it will probably be more possible to set color-specific requirements for the recyclate.” In addition, Bas believes it is important that there is a worldwide standard for recycled plastic: “Each recyclate batch should include a data sheet with technical specs, so that, as a producer, you know the quality you are getting or that you can choose the quality. So far, this quality can only be partially determined, and the bandwidth of the tolerances is often too wide. This would be a big step forward, as well.”

Agreements with machine manufacturer and customer

A final important development that takes place behind the scenes is the contact of the injection molding company with the machine manufacturer and customer. As Bas states: “We receive recycled material from recycling locations in the Netherlands and Germany that comes from collected KeyKegs. These are not grains, but so-called flakes, shreds of the original product. If you look in such a big-bag you recognize the pieces of KeyKeg. Among other things, the size is critical. If the flakes are too small, the amount of dust in the material generally increases. If they are too big, we will either not get them into the machine or they will cause wear and tear of the injection molding machine and extra energy consumption. On the one hand, you are solving a problem, while you are creating a problem on the other hand. So, we consult with our machine supplier and we ask them to do research into injection molding machines that are suitable for processing all kinds of recyclate variants. We also run our own tests. Finally, you have to sit down together with your customer to discuss the risks of damage and mold guarantees. It is really a joint development throughout the entire chain. Customer, injection mold producer, supplier, machine producer, recyclers. Everyone has to participate.”

Important that we celebrate our successes

In his ambitions to achieve operational circular successes, Bas is supported by Wietse Wissema, general director of Alligator Plastics. Wietse is also involved in various board positions for NRK, PVT and ‘Circular Economy in the Netherlands 2050’, working at a national level to get the chain together even more. “At Alligator Plastics, we work hard on sustainability with a lot of passion, and we are happy to talk about it,” says Wietse. “As a branch, we do that through the national Rethink program, among other things. Furthermore, we are committed to a national or international standardization of recyclate, which Bas also mentioned. Together with the government, we look at the legal requirements for plastics. Are they perhaps too strict? Can we create more space for the use of recyclate with a little more bandwidth? Of course, we also contribute to the innovative technologies that the plastics industry is currently working on.”

“There is so much happening in our business. More than the eye can see. More than people realize. That is why a look behind the scenes is very illuminating. Plastics have a lot to offer the world. Together, we must make sure that people do the right things with it.”

More information:
Lightweight Containers and OneCircle: success story about making one-off plastic casks circular.
Rethink: success stories about sustainability in the plastics and rubber industry.
Alligator Plastics and the circular economy: our own efforts for people and the planet.