STUDIES ON PRODUCING HIGH QUALITY CHEMICAL PULP OF SOFT WOOD BY LARCH

摘要

It's very difficult to obtain good quality chemical pulp of softwood by traditional sulfate process because of deficiencies of larch's chemical composition and fiber morphology. In our studies, the larch AS-AQ pulping is gained under the following suitable conditions: total chemical 30% (as NaOH), sulfitity 0.85, anthraquinone charge 0.1 %,maximum cooking temperature 170℃,cooking at 170℃ for 360min,liquid ratio 4:l.Under the conditions, the chemical pulp could be obtained with a yield of 42～45%, Kappa number 35～40, brightness of unbleaching pulp over 30% ISO. After CEH and CEHP bleaching sequences, the brightness could reach 81.6% ISO and 86.4% ISO respectively. When the larch AS-AQ bleaching pulp is beaten by Valley to 45°SR, physical strengthes of this pulp are as follows: tensile index 113.6N·m/g, tear index 9.2mNm2/g, both values are higher than National Standard of thernPeople's Republic of China - Br-A(A grade bleaching sulfate soft wood pulp)intensity standard in QB/T1778-1993.