| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing bleached pulp having extremely improved pulp viscosity and fading characteristics in a method for producing bleached pulp, with which unbleached pulp obtained by digesting a lignocellulose substance is delignified with an alkali and oxygen and then treated by a multistage bleaching process not using an elemental chlorine. SOLUTION: The method for producing bleached pulp comprises delignifying unbleached pulp obtained by digesting a lignocellulose substance, then treating the pulp with an acid at pH 1.5-4.5 at the early stage of a reaction at 30°C-75°C, then subjecting the pulp to ECF (elemental chlorine-free) bleaching by a multistage bleaching sequence for adding chlorine dioxide in≥0.7 mass % of chlorine dioxide addition ratio based on bone dry pulp at a first-stage chlorine dioxide bleaching stage (DO stage) so as to make≤15 mmol hexeneuronic acid amount of completely bleached pulp based on bone dry pulp. COPYRIGHT: (C)2005,JPO&NCIPI
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