| 摘要 |
A process for the preparation of dissolving pulp comprises breaking the lignocellulosic material down chemically, washing the resulting pulp suspension, optionally screening the suspension and removing resin separately, and bleaching (including an alkali treatment) in at least one step. In between at least the majority of treatment steps the suspension is washed and/or concentrated. At any position in the refining process the pulp is fractionated in one or more steps to form at least two fractions, the first of which has a relatively high R10 value, corresponding to the resistance to 10 % sodium hydroxide, compared with the initial pulp, which indicates a relatively high alpha -cellulose content. A second fraction has a relatively low R10 value compared with the initial pulp. Fractionation of the pulp is carried out in a way that increases the R10 value for the first fraction by at least 1 % compared to the initial pulp, and that yields a first fraction comprising 10-55 wt.% of the initial pulp. |
