Pilot-made, highly extensible paper for dry 3D forming

Cellulose fiber-based packaging materials must perform well in demanding three dimensional (3D) forming process conditions. On the other hand, the development of manufacturing concepts is required for improved competitiveness of bio-based materials. This study covers some key factors that influence the extensibility of cellulose fiber-based structures and presents a pilot-scale development study of a 3D formable material concept. Bleached softwood kraft (BSK) pulp from a Nordic pulp mill was used in the pilot trials. Cellulose-based webs were formed using water-laid and foam-laid web forming using a pilot paper machine. For the water-laid forming, the BSK pulp was refined by applying a high consistency (HC) phase at over 40% consistency, followed by a low consistency (LC) refining at 4% consistency. The BSK pulp was refined for the foam-laid forming by only applying lowconsistency refining. In the foam-laid web forming, anionic sodium dodecyl sulfate (SDS), two foamable latexes, and polyvinyl alcohol (PVA) were used as foaming agents. The pilot rolls were dried at a separate steam cylinder dryer pilot and compacted in-plane in the machine direction (MD) at a separate pilot machine. Tensile properties of the treated paper webs were measured and evaluated with respect to achieved web shrinkage. The same dimensional contraction brought by shrinkage was almost strained out in tensile testing. The results indicated that the shrinkage that occurred by drying and in-plane compaction depended on the pulp furnish. The water-laid material achieved about 30% elongation, whereas the foam-laid material achieved significantly above 50% elongation. The 3D forming performance of the dry materials was tested using fixed and sliding blank methods. The dry paper sheets performed well enough in 3D forming for application to many consumer package applications according to their extensibility.