Making the impossible possible: Recycling multilayer packaging

Was multi-layer packaging the Achilles' heel of the recycling industry? Not anymore, according to Krones and their project partners BASF, Südpack, and Tomra. Together, they're unveiling a solution that accomplishes what was once deemed impossible. At the heart of this innovation is a new adhesive that enables effective material separation during the recycling process.

In an interview with K-MAG, Lukas Hausladen, who is well-versed in Krones' recycling solutions, offers insights into this game-changing development. He breaks down how the process works, the challenges they had to overcome, and Krones' role in this collaborative effort. It’s a glimpse into a future where multi-layer packaging doesn't have to spell the end of the recycling line.

Can you break down why recycling multi-layer packaging has been a challenge up to now?

Lukas Hausladen: Until now, separating the layers in multi-layer packaging has been practically impossible, making them essentially non-recyclable. Thermal treatment was the only viable recycling method. Multi-layer packaging can vary in structure. Mostly, two or more material melts are fused together during extrusion, making post-process separation virtually unachievable. However, there is also laminating, where two materials are bonded with an adhesive. This is where BASF and Südpack have focused their efforts, sustainably optimizing this adhesive.

How exactly was it optimized?

Hausladen: BASF, in collaboration with Südpack, has developed an adhesive that can be dissolved during the intensive washing phase of PET recycling. This allows the two bonded materials to beseparated in the recycling process. The primary goal here is to recycle valuable PET material, although processing PE is also possible as a subsequent step.

How does this recycling process work?

Hausladen: It's based on the standard PET recycling process. After shredding and pre-washing the material, it undergoes intensive washing. At this stage, the adhesive dissolves in hot detergent solution, allowing the two material components to separate. Following this, the PE portion is separated from the PET stream through density separation. After the cleaning process is complete, even reusing the decontaminated PET in food packaging becomes a possibility.

Krones didn't develop any new recycling machinery or procedures for this project. The aim was to create a novel adhesive that would allow materials to be separated during the standard process. This would enable multi-layer packaging to be processed using existing recycling channels. Our role at Krones was to evaluate how effectively the multi-layer packaging could be separated. For this purpose, we provided the pilot plant as well as our analytical expertise.

Are there specific types of multi-layer packaging that are especially challenging to recycle? How is Krones addressing this?

Hausladen: Mixed materials in the masterbatch, or as previously mentioned in extrusion, currently can't be materially recycled. These materials are sorted out in sorting plants (for example, using Tomra sorters) and make it to the recycling plants only in minimal quantities. We're supporting the future development of fully recyclable packaging by continually optimizing our recycling process andalso by contributing to this project.

What is the current recycling rate? How can it be further increased?

Hausladen: The rate at which multi-layer packaging is separated, the individual materials processed, and then reused is probably close to zero right now. That is why this project is so crucial. The more materials using this adhesive enter the market, the more likely it is that a separate material stream can be recycled. In this way, high-quality products can be created again.

What has been the most exciting part for you personally in the development of this process?

Hausladen: BASF and Südpack have invested a lot of effort into developing this novel adhesive. In the Krones lab, we replicated the recycling process and saw that material separation for multi-layerpackaging can work. But how well it actually works can only be determined through apilot-scale test. Therefore, seeing the recycling process in action at the pilot plant was the final and most critical step. Being able to observe material separation live in the density separator was incredibly exciting and motivating for the advancement of recycling as a whole.