properties of bleached alkaline sulfite anthraquinone pulp from old corrugated container

the properties of alkaline sulfite anthraquinone (as/aq) pulp from old corrugated container (occ)was studied. in each trial 100 grams (based on dry weigth) of occ and 18% active alkali was used.three levels of anthraquinone (0.0.1 and 0.2% based on dry weigth of the occ) and two pulpingtimes (120 and 150 minutes at maximum pulping temperature) were applied. pulping temperature,na2so3/naoh ratio and liquor to occ ratio at 170ºc,30/70 and 8/1 respectively were constant in allpulping trials. the results showed that the effect of pulping temperature on pulp kappa number, aq onpulping yield and kappa number and the interactive effect of time and aq on pulp yield and kappanumber were statistically significant at 99% level. the highest yield was reached applying pulpingcondition of 18% active alkali,pulping time of 150 minutes pulping time without the addition of aqand the lowest kappa number was related to pulps produced applying 18% active alkali, 0.2% aq and150 minutes pulping time. the results of pulp strength measurements revealed that pulp producedapplying 18% active alkali, 150 minutes pulping time without aq exhibited the highest tensilestrength index at 24.6 n.m/g and the highest tear strength index at 10.54 mn.m2/g was related to pulpproduced applying 18% active alkali, 150 minutes time and 0.2% aq. pulps produced applying 18%active alkali, 150 minutes pulping time and 0.1% aq was selected for elemental chlorine free (ecf)bleaching applying d0epd1 bleaching sequence and kappa factor of 0.35. the brightness, opacity andyellowness of the bleached pulp were determined as 82.6%, 80.22% and 5.64% respectively. thebleaching yield was measured as 92.1% (based in the dry weigth of unbleached pulp) and the tensilestrength and tear strength indices of bleached pulp were 17.88 n.m/g and 10.48 mn.m2/g respectively.