Effect of refining on strength efficiency in twin-wire roll forming of never-dried unbleached softwood kraft pulp
Bengt Nordström, SCA R&D Centre, Sundsvall, Sweden and Lennart Hermansson, Innventia AB, Stockholm, Sweden
Whereas refining is required for the strength development of chemical pulps, it has been unclear how refining affects the utilization of the furnish strength, as reflected by the handsheet strength, in the machine-made paper (strength efficiency). This work examined effects of refining on formation and strength efficiency in twin-wire roll forming of never-dried unbleached softwood kraft pulp in a pilot machine investigation comprising three separate sections.
The first section showed that a change in refining energy has no significant effect on formation, tensile strength efficiency, tensile stiffness efficiency, or compression strength efficiency at a given consistency when the fiber length remains similar. The second section demonstrated that a change in kappa number has no significant effect on formation or tensile strength efficiency at a given consistency when the fiber length of the refined pulp remains similar. Here, an increase in kappa number involved an increase in refining energy. The third section showed that a reduction in headbox consistency results in an improvement in formation and tensile strength efficiency that is similar in magnitude over the whole refining curve.
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. Open Access: Articles not available through Gold Open Access may be purchased by credit card as a pdf file, to be downloaded within 24 h after ordering, at a price of 22 EUR per article. (Value added tax may apply depending on your location, which you enter at payment logout.) Such articles have Green Open Access, i.e. authors may share articles on their personal non-commerical homepage immediately after publication on the website and download them to non-commercial hosting platforms one year after publication in a full issue of NPPRJ. ISSN: 0283-2631