Optimal mechanical pulp fibres for improved publication paper : targets and treatments

A study was undertaken to identify the optimal structure of mechanical pulp fibres for wood-containing publication papers. Mechanical pulps for improved wood-containing publication papers should have thin-walled fibres, large degree of fibre splitting, fibrillated fibre surfaces, and low amount of shives (especially latewood shives. Such fibre properties will give publication papers with improved print quality, formation and runability. To achieve such fibre characteristics, the TMP process can be modified by partial defibration in an impressafiner prior to the primary stage, followed by high-intensity refining. One should spend most energy where it is most effectively applied; at the thick-walled fibres. This may be achieved through fractionation of fibres based on wall thickness, followed by separate refining of thick- and thin-walled fibres. These modifications may reduce the energy consumptions in TMP producton and give improved product quality.