Delignification of refiner mechanical pulps from Albizia lebbek and Eucalyptus hybrid by sulphate process.
Barked wood of Albizia lebbek and Eucalyptus hybrid [E. tereticornis] was chipped and refiner mechanical pulp prepared by passing chips soaked overnight in water through a 30-cm laboratory disc refiner (the Sprout Waldron disc refiner) at 30 mil, followed by further refining at 5 mil. Unbleached screened pulp yields were respectively 94 and 93%. The pulp was then treated by the sulfate process using 6-14% NaOH + Na2S, with a material/liquor ratio of 1:4, sulfide 25%, temperature 162°C and cooking time 3 h. Data are presented on the resulting pulp unbleached yields and strength properties (burst, tear and tensile indices). The results showed that 8% NaOH + Na2S gave high yields (around 60%) with strength properties almost equal to those of kraft pulp (yield 45%). The results were also better than those obtained in previous tests of delignification of refiner mechanical pulp using the soda process.