AMBIENT TEMPERATURE PULP BLEACHING WITH PEROXYACID SALTS

摘要

The present invention relates to a Kraft pulp bleaching stage which is to be carried out after conventional bleaching stages to high brightness. It has been discovered that ambient-temperature blaching with inorganic peroxyacid salts, such as peroxymonosulfates, at this point can provide substantial increases in pulp brightness without significant decreases in pulp viscosity. Peroxyacid bleaching according to the present invention is carried out at ambient temperature and no greater than about 40 ~C and at an initial pH that is slightly alkaline and preferably about 7.25.