Advanced moisture strategy for expanded formability in paper-based packaging

Abstract The growing demand for sustainable packaging solutions is driving the development of new paper-based forming processes. Among these, 3D forming of paper has shown particular promise (Groche, P. and Huttel, D. (2015). Paperboard forming - specifics compared to sheet metal forming. BioRes 11). However, limited formability remains a key challenge, restricting potential applications. Since moisture content significantly affects both bending stiffness and stretchability (Franke, W.; Stein, P.; Dörsam, S.; Groche, P. (2018): Formability of paperboard during deep-drawing with local steam application. In: Proceedings of the 21ST international esaform conference on material forming . ESAFORM 2018, Palermo, Italy, 2018: Author(s) (AIP Conference Proceedings), S. 100008), targeted moistening is critical. For high-speed packaging lines with cycle times of 1–3 s, rapid and controlled moistening is required. Previous studies have shown that methods like water baths or sponge applications can improve forming results especially when combined with pressure to ensure even moisture distribution (Stotz, H., Vogt, L., Kasparian, T., Klauser, M., Rauschnabel, J., and Hauptmann, M. (2022). TAPPICon 2022 - advanced development in 3D forming methods for paper packaging . Charlotte, North Carolina, USA, 30 April-4 May 2022. Curran Associates, Inc., Red Hook, NY). However, practical, process-integrated solutions have been lacking. This study investigates a newly developed moistening unit using a porous aluminum interface for one-sided application (Bischoff, B.; Stotz, H.; Klauser, M. (2023). Verfahren und vorrichtung zur herstellung eines verpackungselementes . Angemeldet durch Syntegon Technology GmbH am 05.05.2023. Anmeldenr: 23171862.8. Veröffentlichungsnr.: EP 4 292 805 A1). Experiments with bleached board demonstrated that higher water pressure and longer contact times significantly increased moisture content. Moisture levels of up to 26 % were achieved in just 1–3 s. As a result, formability improved noticeably: the maximum strain increased from 13 % to 19 %, enabling deeper geometries and steeper wall angles – a clear advancement for sustainable packaging design.