Multilayer Packaging Recyclable on an Industrial Scale

Packaging made from multifunctional multilayer films is indispensable for the protection and shelf life of food but is also used for other packaging. Until now, however, they have had the shortcoming of not being recyclable. This is because when plastic films are bonded together, the resulting composites are difficult or impossible to separate. In a project with partners Südpack, Krones and Tomra, the chemical company and adhesives manufacturer BASF has now shown how the components can be returned to the material cycle. Already in the first industrial trial, 69 percent of the PET and PE layers of a two-layer packaging shredded into flakes were completely separated from each other, and 12 percent were partially separated, according to the companies involved. This was technologically successful “with existing infrastructure,” they say.

According to the European Green Deal, a large proportion of packaging must be recycled by 2030. The details of this will be regulated in future in the Packaging and Packaging Waste Regulation (PPWR), the draft of which was presented in November 2022. However, the recycling of multilayer films has been difficult to date due to the use of different materials.

In early 2021, Tomra sorted PET/PE packaging produced by film laminator Südpack into a single-sort waste stream for the first time, according to the latest interim report. To do this, recyclable trays first had to be separated from non-recyclable ones. A water-based adhesive from the Ludwigshafen-based company used by the Oberschwaben-based company was crucial for their identification. Tomra adjusted its own “Autosort” near-infrared recognition system, which is installed in many sorting plants, to the individual characteristics of this substance.

Special adhesives are the basis

“As part of the joint project, we are contributing our many years of expertise in the field of lamination. Thanks to our special know-how in water-based lamination, we can produce multilayer films that can be separated by alkaline hot-wash processes,” says Carolin Grimbacher, Managing Partner at Südpack.

Special adhesives used in laminating functionally different films form the basis for the separability of the film components. It is important that the laminating adhesive adheres securely until after a package has been emptied but allows the two films to be separated as easily as possible during recycling.

At this stage of the project, machine manufacturer Krones came on board in 2022. In a pilot plant owned by the company in Flensburg, tests were run to separate PET and PE from the composite films on an industrial scale. A process commonly used in the classic recycling of PET beverage bottles was used, known as “alkaline hot washing”. This allowed the two materials to be separated successfully.

“We have proven that delamination of multilayer films works. The separation of the films can be further improved by optimizing individual process parameters and the particle size of the flakes,” says Thore Lucks, Head of Technology Recycling Solutions at Krones.

“We consider the fact that we were able to completely separate 69 percent of the packaging during the first industrial trial a great success. This can certainly be further extended by improving our debonding adhesive system,” explains Kresimir Cule, Commercial Marketing Industrial Adhesives, at BASF SE.

The project is currently being continued. The goal is to reuse the recycled PET for the production of food packaging and the PE fraction as a raw material for new non-food packaging.