NORDIC PULP & PAPER RESEARCH JOURNAL
Home » Volume 32, 2017 » Issue No. 4
PAPER PHYSICS
Successive twin-wire roll forming of two-ply paper with softwood kraft pulp and recycled pulp – effect of kraft-ply formation on Z-strength - OPEN ACCESS
Bengt Nordström and Lennart Hermansson
Abstract
Kraftliner and kraft-top liner typically consists of two or more plies that are formed separately and combined by couching. The Z-strength tends to be limited by the ply adhesion, and the softwood kraft pulp used is commonly refined beyond the optimum for tensile strength to ensure sufficient Z-strength.
In this work, two-ply forming by successive twin-wire roll forming, was evaluated with moderately refined never-dried unbleached softwood kraft pulp and recycled pulp in different plies. Successive twin-wire roll forming involved two-sided roll forming of the first ply and one-sided roll forming of the second ply directly onto the first ply. Two-sided roll forming of the recycled pulp and one-sided roll forming of the kraft pulp was evaluated in parallel to the reversed combination.
The Z-strength was found to be limited by the strength of the kraft ply rather than by the ply adhesion. The effect on Z-strength when changing headbox consistency or when going from one-sided to two-sided roll forming for the kraft ply was in agreement with results for single-ply forming. Besides the favorable findings for Z-strength, the results suggest that successive roll forming enables an efficient utilization of the tensile strength potential of the softwood kraft pulp.
Keywords
Formation, Forming sections, Kraft pulps, Liner boards, Multiply boards, Reclaimed fibers, Tensile strength, Z-direction strength
Pages
639-646
DOI
10.3183/NPPRJ-2017-32-04-p639-646
Full text
PDF Document N2017-32-04_p639-646_Nordstrom.pdf (385KB)
Successive twin-wire roll forming of two-ply paper with softwood kraft pulp and recycled pulp – effect of kraft-ply formation on Z-strength - OPEN ACCESS (2017-32-04_p639-646_Nordstrom.pdf)
Nordic Pulp & Paper Research Journal (NPPRJ) is an international scientific magazine covering science and technology for the areas of wood or bio-mass constituents, pulp and paper and including new fiber-based materials, recovery and by-products from pulping processes, bio-refining and energy issues. Articles meeting required scientific standards are accepted from any continent.
ISSN: 0283-2631