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 pulping times (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 all pulping trials. The results showed that the effect of pulping temperature on pulp kappa number, AQ on pulping yield and kappa number and the interactive effect of time and AQ on pulp yield and kappa number were statistically significant at 99% level. The highest yield was reached applying pulping condition of 18% active alkali,pulping time of 150 minutes pulping time without the addition of AQ and the lowest kappa number was related to pulps produced applying 18% active alkali, 0.2% AQ and 150 minutes pulping time. The results of pulp strength measurements revealed that pulp produced applying 18% active alkali, 150 minutes pulping time without AQ exhibited the highest tensile strength index at 24.6 N.m/g and the highest tear strength index at 10.54 mN.m2/g was related to pulp produced 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 and yellowness of the bleached pulp were determined as 82.6%, 80.22% and 5.64% respectively. The bleaching yield was measured as 92.1% (based in the dry weigth of unbleached pulp) and the tensile strength and tear strength indices of bleached pulp were 17.88 N.m/g and 10.48 mN.m /g respectively.