MULTISTEP SULFITE CELLULOSE BLEACHING PROCESS Russian patent published in 2006 - IPC D21C9/12 

FIELD: paper-and-pulp industry.

SUBSTANCE: invention is designed for use in production of bleached sulfite cellulose with reduced level of resins and fats for manufacturing paper and cardboard in multistep bleaching processes. Process according to invention comprises treatment of pulp with sodium hypochlorite solution in presence of chemical additive, bucking and souring of pulp, sad chemical additive being aqueous mixture of ethoxylated fatty alcohols having density 0.99-1.1 g/cm³ in amount 0.04-0.08% of the weight of absolutely dry cellulose. Bucking of pulp is carried out in presence of detergent named VIK-1 used in amount 0.1-0.3% of the weight of absolutely dry cellulose. Souring is carried out in presence of aqueous solution of quaternary polyammonium compound (BZK-2) used in amount 0.4-0.8% of the weight of absolutely dry cellulose.

EFFECT: reduced gumminess of bleached sulfite cellulose and enhanced whiteness at the same cost.

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