The Low-Kappa Number Pulping Of The Triploid Of Populus Tomentosa And Bleaching Of The Pulp To High Brightness

In the paper, the NaOH-AQ pulp with low-kappa number from the triploid of tomentosa was obtained by simple pretreatment and conventional cooking. Oxygen delignification, strengthened oxygen delignification, TCF and ECF high brightness bleaching of triploid of populus tomentosa of NaOH-AQ pulp with lower kappa was studied in lab, which would offer support for producing high quality chemical pulps in technology and mechanisms.The experiment research on high temperature steaming pretreatment, high temperature black liquor pretreatment, screw extrusion after precooking with black liquor or hot water as the cooking pretreatment was carried out in NaOH-AQ cooking or Kraft pulp cooking with lower kappa number. Under keeping yield invariable, the kappa number was below 15 and extended delignification of the triploid of populus tomentosa was realized.The research work on oxygen delignification and strengthened oxygen delignification of triploid of populus tomentosa of NaOH-AQ pulp with lower kappa number indicated that the oxygen delignification and strengthened oxygen delignification pulp which have better viscosity, lower kappa number and high brightness and yield under the optimal technics conditions.The experiment research on TCF high brightness bleaching of the NaOH-AQ pulp with low-kappa number from the triploid of tomentosa with strengthened oxygen delignification and H₂O₂ bleaching technique was studied by (Q/Op)QP sequence. Under the better technique conditions, the brightness of bleaching pulp could reach 82%ISO and the pulp keep relatively high strength.The bleachability of low kappa number Soda-AQ pulp of trioploid of tomentosa were studied by using oxygen delignification, H₂O₂ bleaching in the oxygen pressure(shortened form Op)and ClO2 bleaching. The pulp with the brightness of 85.6%ISO and viscosity of 701ml/g could be obtained by ODED bleaching sequence and the brightness of 88.3%ISO and viscosity of 681ml/g could be obtained by OPDQP bleaching sequence. The results show that the two bleaching sequences are suitable for low kappa number NaOH-AQ pulp of the trioploid of tomentosa. The strenth properties of the hand sheets from the ODED and OpDQP bleached pulps were high enough for the production of high grade paper. The bleaching principium of oxygen delignification pulp, strengthened oxygen delignification pulp, TCF bleaching pulp, ODED bleaching and OPDQP bleaching of triploid of populus tomentosa of NaOH-AQ pulp with lower kappa number was researched by infrared spectrum.Finally,the NaOH-AQ pulp of trioploid of tomentosa was bleached using the chlorine dioxide which was activated by hydrochloric acid and sulfur acid respectively. The similar bleached pulp properties were obtained under the different acid activation and the same time, temperature and chemical dosages etc. It was possible that the bleaching effect of activated chlorine dioxide just related with pH value.