Profiles for fiber products:Fibre profile for board

In recombining pulp fractions, highest bulk at a given Scott Bond level was achieved when the stiffest mechanical pulp fibres were mixed with kraft fines. Mechanical pulp fines also effectively enhanced strength, although more mechanical pulp fines were needed compared to kraft fines to reach a given Scott Bond or Z-strength level. The addition of fines to the long-fibre fraction or middle fraction influenced strength properties differently. This explains how high-bulk board can be produced from pulps of both high and low average fibre length. The potential to improve bulk with the tailored pulp fractions was c. 30% compared to pure mainline-refined TMP or CTMP. The top layer of board requires high tensile stiffness (modulus of elasticity) as well as high porosity to facilitate drying on the board machine. This high porosity could be achieved by removing the fines (and middle fractions) from well-refined pulp