Paper joining without foreign substances

The processing of cellulose and the analysis of fiber materials are among the main areas of research and development at Fraunhofer IAP. In the “Papure” project, we characterize coated and uncoated papers for packaging applications to determine whether they are suitable for joining without the application of additional foreign substances. Particular attention is paid to identifying the cellulose, hemicellulose and lignin content of the papers, as these significantly influence the adhesive properties of the materials after laser treatment.

To this end, we are investigating the chemical composition and morphology of the different papers before laser treatment and the reaction products afterwards. We use a wide range of analytical methods such as scanning electron microscopy (SEM), high-performance anion exchange chromatography (HPAE), and X-ray photoelectron spectroscopy (XPS).

Further information can be found on our website!

Fraunhofer IWS contributes its expertise in laser system engineering, laser-based materials processing, and the modification of natural materials to the PAPURE project. Between 2019 and 2021, the team developed a binder-free bonding process for paper. Irradiation with a carbon monoxide laser generated meltable reaction products, enabling the team to create a cohesive joint between two paper layers in a subsequent heat-sealing step. High-speed recordings of the CO laser irradiation show the material’s short-lived liquid phase.

The current project phase focuses on refining the laser process and implementing the technology under real manufacturing conditions in the demonstrator system.

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The Fraunhofer Institute for Process Engineering and Packaging develops innovative packaging processes and technologies. We have the most comprehensive portfolio of established and innovative joining technologies in Germany. We are constantly refining these technologies and processes and optimizing them for specific applications, whilst always taking into account the interaction between packaging material, packaged goods, and machinery.

For the “Papure” project, we are developing a joining system for processing laser-treated paper with fusible reaction products. To this end, we are investigating the influence of material properties, laser parameters, and the properties of the fusible reaction products on adhesive strength. We are developing a joining system and testing the extent to which suitable joining parameters and tool geometries can improve seam strength and tightness.  In addition, we are transferring the results to a packaging solution with the aim of achieving market-driven joining seam properties.

Further information can be found on our project page!

Within the Papure project, Fraunhofer IWU is developing a demonstrator that transfers research results into an industry-oriented process and demonstrates practical suitability for the packaging industry. The aim is to create a sustainable alternative to conventional adhesive processes: an adhesive-free paper bond – entirely without additional chemicals.

The demonstrator replicates a complete manufacturing process for a typical packaging product. The focus of the solution is on the integration of a laser system into a mechanical paper processing line. Central challenges are addressed, such as optical radiation protection, straightforward and robust construction, as well as seamless integration into classic paper machine concepts.

To ensure process stability, Fraunhofer IWU relies on industry-proven sensor technology, the collection and analysis of relevant process parameters, and the use of data-driven models. This approach will allow for a significant increase in cycle times in the future – a decisive step towards economic implementation on an industrial scale.

As tangible proof of feasibility, the demonstrator produces a four-sided sealed pouch. This sample product not only demonstrates the technical realisation but also highlights the benefits of the new technology for the packaging industry.

Outlook: With the demonstrator, Fraunhofer IWU is presenting a forward-looking solution that convinces industrial partners and paves the way for sustainable packaging concepts. The technology can be integrated into existing production lines and forms the basis for pilot and series applications. In this way, the Papure project makes an important contribution to resource conservation and the circular economy

Further information can be found on our project page!