Dr. Retsch, why are aluminum-plastic laminates (APLs) so popular for food packaging such as potato chip bags?
Dr. Markus Retsch: APLs are often used for food packaging because they create a barrier layer. This prevents air and water from passing through the packaging plastic. This keeps the packaged food in the bag fresh and durable for longer.
Why are APLs a challenge for common recycling processes?
Dr. Retsch: The problem with APL packaging is their combination of different material classes. The aluminum used cannot be mechanically or thermally recycled like other plastics and thus leads to contamination of the recycled plastics. In addition, the thin aluminum layer is firmly welded to the surrounding polymer films, so that this foreign material cannot be separated from the plastic film. Overall, this means that such packaging films can hardly be recycled.
How did you come up with the idea of using APL packaging for energy-saving cooling foils?
Dr. Retsch: Through our many years of research into novel materials with passive cooling properties, we had long been on the lookout for a cost-effective but high-quality source of highly reflective materials. So it came about that we took a closer look at the inside of such packaging films. A special property of these aluminum-plastic composite films is that they have a highly reflective surface on their non-printed side, i.e. on the inside. This ultimately gave rise to the idea of recycling these packaging films and making them usable for passive cooling applications.