| 摘要 |
<p>PROBLEM TO BE SOLVED: To produce bleached pulp having stable high quality for high quality paper grade by cooking waste paper raw material containing waste paper of newspaper in a specific percentage by weight or more, subjecting the obtained pulp to delignification with oxygen and deinking followed by a multistage bleaching treatment. SOLUTION: A waste paper raw material containing waste paper of newspaper in an amount of 60-90 wt.% of the total waste paper raw material is subjected to dissociation, dehydration and further cooking to obtain pulp having a kappa value of 10-40, and the obtained pulp is subjected to delignification with oxygen and subsequently deinking. After these treatments, the pulp is subjected to a multistage bleaching treatment, for example, a four stage bleaching treatment of chlorine treatment-alkali treatment-sodium hypochlorite treatment-chlorine dioxide treatment with the result that the objective bleached pulp is obtained from waste paper.</p> |
