Thermomechanical pulp from jack pine: Reduction of the extractives content by chip pretreatment

The effect on pulp characteristics of an extraction of pretreated chips' prior to a two-stage alkaline peroxide thermomechanical process has been examined. Partial removal of the extractives in an early stage of the process improved the fibre properties, reduced the extractives content of the resulting pulp, and increased the bleachability of the final pulps. Various chemicals, such as water, methanol, H2O2, NaOH, Na2SO3 or a combination of them, were tested in the steeping of chips prior to mechanical extraction. The results clearly show the potential use of jack pine (Pinus banksiana Lamb.) in producing a high yield commercial pulp comparable in quality to other softwood market pulps.