method for chlorine free bleached pulp and delignifizierung.

摘要

Cl-free bleaching and delignification of cellulose pre-bleached with O2 and peroxide, or O2 and O3, involves a 2-stage treatment with peroxide activated with cyanamide and/or cyanamide salts. - In the first stage, the content of cyanamide and/or cyanamide salts is 0.05-0.5 (0.07-0.33) wt.%, and the peroxide content is 0.1-1 wt.%, both w.r.t. dry wt. of cellulose. In the second stage, the content of cyanamide is 0.01-0.3 (0.03-0.23) wt.%, and the peroxide content is 0.1-0.7 wt.%, w.r.t. dry wt. of cellulose. Both stages are at pH 10-12, solids content of 5-30 (7-20) wt.%, and 40-90 (55-80) deg.C, for 1-6h for each stage.