SULFITE-FORMALDEHYDE PULPING AND OXYGEN DELIGNIFICATION OF WHEAT STRAW

摘要

Wheat straw pulp was prepared using sulfite formaldehyde (SF) pulping and oxygen delignification. Bleachability of SF pulp after oxygen stage was evaluated by hypochlorite bleaching. The results show that Na_2SO_3 charge plays an important role on both SF pulping and oxygen delignification. The efficiency of oxygen delignification is rather high on wheat straw SF pulp. The decrease of Kappa number after oxygen stage is over 50% while original Kappa number of SF pulp is lower than 30 and NaOH charge is 3%～5%. The proper charges of sulfite and formaldehyde for preparing bleached pulp for SF pulping and oxygen delignification are 14% and 4% respectively. Pulp with relatively high brightness, low Kappa number, as well as acceptable viscosity could be obtained if oxygen delignified SF pulp was bleached by hypochlorite under a low active chlorine dosage.