A light drainability, bulky chemimechanical pulp that has a low shive content and a low fine-material content

摘要

PCT No. PCT/SE95/00670 Sec. 371 Date Dec. 13, 1996 Sec. 102(e) Date Dec. 13, 1996 PCT Filed Jun. 7, 1995 PCT Pub. No. WO95/34711 PCT Pub. Date Dec. 21, 1995A chemimechanical pulp for use in the manufacture of paper or paperboard products where a high drainability, bulky pulp is desired. The pulp has a long fiber content of between 60 and 75%, a fine-material content of at most 14%, a shive content of less than 0.5%, is refined to a freeness of 600 ml CSF at the lowest, and has a tensile index of at least 10 kNm/kg. A method for producing such a pulp comprises: a) impregnating chips with a lignin softening chemical; b) preheating the chips; c) refining the chips to papermaking pulp; wherein the chips are impregnated and heated over a total time period of at most 4 minutes; a) using a hot impregnating liquid having a temperature of at least 130 DEG C.; b) preheating the chips at a temperature above the lignin softening temperature; c) refining the pulp in one or more stages, of which the first or sole stage is carried out solely at essentially the same pressure and the same temperature as the preheating process; and refining the pulp at a total energy input which is at least 50% and at most 90% of the energy input required to achieve the same shive content when preheating at 135 DEG C. and using the same machine equipment.