Multi-layer film packaging remain a favoured packaging solution choice, particularly in the food industry. Yet, however efficient these solutions may be, they come with one major drawback: unrecyclability, mainly due to the fact that the different layers used to create the packaging are often made from different materials.
And with the European Green Deal looming large - it aims to make all packaging on the EU market recyclable in an economically viable way by 2030 - multi-layered packaging is facing a major challenge. If it is to comply with the upcoming Packaging and Packaging Waste Regulation (PPWR), which will provide the legislative framework for achieving this goal, new structures or technologies must be devised that are able to be more readily recycled.
A joint project between BASF, Krones, Südpack, and Tomra has now demonstrated PET/PE multi-layer packaging can, in fact, be separated into its individual components; these can subsequently go back into the materials cycle as raw materials. During the first industrial trial, conducted at a Krones pilot plant in Flensburg, the partners were able to completely separate as much as 69 percent of the PET/PE components and partially separate another twelve percent. What makes this approach especially attractive is that existing infrastructure is used to recycle the packaging.
The initial phase of the project took place early in 2021 and consisted of sorting trials with PET/PE trays, carried out by Tomra. The trays had been produced by plastic film manufacturer Südpack using a “debonding adhesive” developed by BASF. These adhesives, used during the lamination of multi-layer films, were developed to offer high adhesive strength when required, yet come apartfor recycling purposes.
“Our contribution to the collaboration project was our long-standing expertise in lamination. Using our expert know-how in water-based lamination, we were able to develop multi-layer films that can be separated by caustic hot washing,” said Carolin Grimbacher, a managing partner at Südpack responsible for R&D.
During the trials, Tomra sorted out the recyclable multi-layer films from the waste stream, using its proprietary NIR technology- called Autosort - to achieve this. This technology proved able to detect the multi-layer PET trays containing the BASF adhesive.
Trials were then conducted at one of the pilot plants of Krones, who, among other things, develops plastics recycling systems and who joined the project team in July 2022. Here it was tested whether laminated PET/PE films could be separated back into single layers on an industrial scale. A standard hot washing process commonly used for PET recycling was found to work, after which the separated PET and PE could be re-used as monomaterials.
While it was shown that the delamination of multi-layer films was possible, ‘the separation of the films could still be improved by optimising individual process parameters as well as, for example, the particle size of the flakes’, noted Thore Lucks, head of Techology Recycling Solutions at Krones, explains.
The water-based Epotal adhesives developed by BASF had been tested in the laboratory, and the company was pleased at how well they performed during the industrial trial.
“We consider it a huge success that we were able to completely separate 69 percent of the packaging during our very first industrial trial. We are confident that we will be able to further increase this figure by optimising our debonding adhesive,” said Kresimir Cule, of commercial marketing Industrial Adhesives, at BASF SE.
The project, said the partners, is still ongoing. By adjusting various parameters of the recycling process and by further developing the lamination adhesive used, they see additional opportunities for improving the recycling rate for plastics. The quality of the recycled materials is a major focus. The aim is to be able to re-use the PET for the manufacture of food packaging, while the PE fraction will be used as a raw material to make new packaging for the non-food industry. Studies on this will be carried out shortly.