EFFECT OF LOW CONSISTENCY REFINING AND FRACTIONATION ON FOLDING BOXBOARDS AND DISCRETE ELEMENT MODELLING OF PLYBOND STRENGTH

The effect of using fractionation screens after primary high consistency (HC) refining and prior to low consistency (LC) refining on pulp properties being used as the middle-ply furnish of folding boxboards (FBBs) is investigated. Middle-ply furnish was a mixture of accept and reject pulps resulted from various screening designs, a range of specific refining energies (SRE), and two levels of specific edge load (SEL) and were compared with pulps with no screening stage. Fractionation and LC refining decreased refining energy consumption, and improved fibre uniformity resulting in optimum conditions for physical properties compared to the conventional refining processes. Plybond strength of multi-ply paperboards is modelled using Discrete Elements Method (DEM). Simulated three-ply boards were generated computationally and were subjected to z-directional tensile stress using ESyS-Particles software. It was found that plybond strength of simulated boards can be expressed by a scaling relationship in terms of paperboard density and bond strength.M.A.S