BLEACHING OF SULFITE PULPS WITH PEROXYBEN ZOIC ACID

Sulfite pulp from spruce was bleached by sodium peroxybenzoate. The pr ocess was evaluated by comparing it with a standard hydrogen peroxide bleaching procedure. Perbenzoate as a bleaching agent excels by good r eactivity and an improved selectivity towards lignin. The polysacchari de components of the pulp are less degraded and good mechanical proper ties are achieved. The relationship between kappa-number and brightnes s differs with differently bleached pulps: pulps bleached by hydrogen peroxide show better brightness than peroxybenzoate pulps of the same kappa-number. Compared to peroxyacetic acid, peroxybenzoic acid offers the advantage of easier handling, easier on the site production and p ossible recyclability from the bleaching waste liquor.