METHOD OF BLEACHING MECHANICAL PULP WITH HYDROGEN PEROXIDE

摘要

PURPOSE: To obtain a mechanical pulp with enhanced brightness by treating the pulp in a specific aqueous bleaching composition containing a base, magnesium sulfate, sodium silicate and hydrogen peroxide. CONSTITUTION: This aqueous bleaching composition comprises at least 10 wt.% hydrogen peroxide on the basis of the pulp at a pH of about 9-11 and a base, magnesium sulfate, sodium silicate by ratio or amounts enough to substantially reduce the amount of non-bleaching reaction product of hydrogen peroxide to be wasted. The mechanical pulp is treated in this composition for a time sufficient to obtain the pulp with enhanced brightness and a residual liquid so that the pulp has not less than 80% ISO brightness value.