Background information
More circulation, less waste: recycling plastic in Switzerland
by Coya Vallejo Hägi
How lasers are revolutionising the packaging industry
9.3.2026
Translation: Elicia Payne
Paper packaging’s considered to be recycling-friendly. But of all things, their seal is a problem. Additives, such as adhesives and coatings make recycling more difficult. This is how a new laser process could replace these additives.
Every box of cornflakes, every paper bag, every paper cup has a hidden problem: adhesives or layers of plastic are needed to seal them. It sounds like a small thing, but it’s a real challenge when it comes to recycling. These additives contaminate the paper, make the recycling process more difficult and reduce the quality of recycled material. This virtually eliminates the advantage of a high recycling rate, lower CO2 emissions and low disposal costs.
How big is the problem in the packaging industry?
In fact, this problem affects a large proportion of the market: paper and cardboard are now the most important packaging materials in Europe in terms of volume. They account for around 40 to 45 per cent of all packaging, particularly for food and shipping. The remaining 55 to 60 per cent of the European packaging market consists primarily of plastics (35 to 40 per cent), metal packaging (8 to 10 per cent), glass (5 to 7 per cent) and wooden packaging (3 to 5 per cent).
Many of these products, from folding cartons to snack or flour bags, are sealed with adhesives or plastic. Although these foreign substances often make up only a few per cent of the total mass, they cause disproportionately large difficulties for paper recycling. Since you can’t completely remove the fibres from the packaging, they reduce the quality of the recycled material.
The Papure research project
Four Fraunhofer Institutes want to combat this problem. For the «Papure» research project, the Institutes of Applied Polymer Research (IAP), Materials and Beam Technology (IWS), Process Engineering and Packaging (IVV) and Machine Tools and Forming Technology (IWU) are collaborating on a process that works entirely without adhesives, plastics or other foreign materials. The key component’s a carbon monoxide (CO) laser.
The laser produces its own adhesive
The CO laser operates in the mid-infrared range – its wavelengths are particularly well absorbed by organic paper fibres. As a result, it heats the surface extremely quickly and locally without damaging the material.
By irradiating paper with a carbon monoxide laser, it produces fusible reaction products that bond the paper layers together, i.e. not only by adhesion but also by melting the material. The trick lies in the physics of the material itself. Paper consists mainly of the plant fibres cellulose, hemicellulose and lignin.
Source: Fraunhofer IVV
When the CO laser heats the paper surface abruptly, these main components are converted into short-chain compounds in a controlled manner. These meltable fission products remain on the surface and enable adhesive-free joining.
We virtually produce our own adhesive in the form of the fission products.
The compounds produced are sugary and sticky and can be reactivated during subsequent heat sealing. In other words, there are two stages. First, the laser creates the fusible cleavage products, which are then reheated during the subsequent heat-sealing process and permanently bond the paper layers.
The new approach is to irradiate the paper with the CO laser and in this way produce re-meltable sugar-like fission products that are used to join the paper instead of the plastics or adhesives otherwise required. This would mean the paper already provides its own adhesive and loses it completely after recycling.
Four institutes, one process
The project is a collaboration of individual tasks. The first step is to select the material. There are around three dozen types of paper to choose from. Particular attention is paid to identifying the hemicellulose, cellulose and lignin content of the papers, as these influence the adhesive properties of the materials as well as the quantity and composition of the resulting cleavage products.
An excessively high proportion of inorganic compounds such as talc and calcium carbonate has a negative effect on the adhesive properties and the adhesive strength of the joint seams, as Dr Robert Protz from the Fraunhofer IAP explains. Thicker papers, on the other hand – such as those used for disposable paper cups or other food packaging – work particularly well.
The plant in Dresden
A modular, paper-processing production plant on a laboratory scale is being built at IWU.
Source: Fraunhofer IVV
A laser module and a combined sealing and punching tool are integrated into the system. The continuously fed paper web is first treated with the CO laser, then joined with a second web, combined with four seams using the heat-sealing process and punched out to form the bag.
Source: Fraunhofer IVV
Source: Fraunhofer IVV
The goal is ambitious, but achievable. By the end of the project in September 2026, the laboratory system should be producing ten packages per minute. The desired seam strength even goes beyond the paper itself. The seal seam should be more stable than the material around it.
The procedure still has to prove itself
It’s currently unclear how well the process works with coated papers or papers with a high mineral content. Both are widely used in the packaging market. The sealed seams’ resistance to moisture, grease or low temperatures also needs to be tested under real conditions.
Another decisive factor will be whether the process can achieve the high cycle speeds of industrial packaging lines in the long term, some of which currently achieve several hundred units per minute.
Ready for the industry
Despite these open questions, the process has been designed for industrial practice from the get-go. The Papure system can be retrofitted as an extension to existing production lines.
In the next step, the project partners want to work together with companies from the packaging and food industry to examine how the laboratory results can be transferred to large-scale production processes. In order to move the process towards series production, paper manufacturers and machine builders are also supposed to be involved.
Header image: Fraunhofer IVV
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