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Called oneBARRIER FibreCycle, its base substrate is UPM Solide Lucent™, a responsibly sourced and recyclable kraft paper especially well-suited for packaging, due to its high density, folding performance, and overall coatability. The paper's smoothness, porosity, and mechanical performance make it an excellent foundation for achieving optimum barrier properties.
As noted by Janne Varvemaa, Director, Products & Technology, UPM Specialty Papers, “By itself, our Solide Lucent paper is not ready for end-uses where high barriers are required, so a major focus of the co-creation project was developing the coating layers.”
The coating system, developed by Michelman, is built around a novel, multifunctional coating with excellent adhesion to the paper. This single base coating provides oxygen, moisture, and mineral oil barriers, oil and grease resistance, and print receptivity, while aiding the metallization process. This mitigates the need for additional, separate coatings at the priming step and helps to maintain recyclability and food contact compliance.
In addition, as part of the total packaging solution, Michelman has developed a range of heat seal coatings, optimized for different seal initiation temperatures (SITs) and further enhancing moisture barrier properties, taking into account coefficient of friction (CoF) requirements for different packing lines. These coatings are applied over the metallization layer to protect the metal and ensure a tight seal on the package.
To complete the system, a Michelman-designed overprint varnish (OPV) with additional moisture barrier properties is applied over the print, bringing the overall performance into the required range for high barrier food packaging with an extended shelf life.
Putting the substrate and coating system together successfully is Bobst 's expertise in equipment design, application know-how, and optimization of the converting process, necessary to obtain the smooth, pinhole-free surface required for subsequent vacuum metallization. This hinges on selecting the best coating method and tailoring the drying profile to the primer chemistry, resulting in optimum film formation and barrier properties.
“UPM’s Solide Lucent paper was a strong basis from which to start the development and only required a few modifications. We supplied the AluBond and AlOx (aluminium oxide) technologies, and Michelman produced the primary topcoat materials. Overall, the in-depth technical understanding we each brought to the table complemented one another,” explains Nick Copeland, Research & Development Director, Bobst.
Thierry Van Migem, Sales Director, EMEA, Michelman, agrees. “By working together and not in silos, we are able to identify issues and adjust rapidly, promoting an agile way of working and improving speed to market. By uniting our respective expertise, the total performance of the oneBARRIER FibreCycle solution is better than we could have achieved separately.”
Varvemaa concludes, “It was very inspiring working together with Bobst and Michelman, who are true experts in their respective fields. I found the cooperation fruitful and open, with straightforward and trusting communications. I believe that together we managed to create a world-leading barrier solution that offers brand owners a packaging solution that is not only sustainable, but also delivers on functionality.”