Method for producing bleached wood fibre material

The invention relates to a method for producing bleached wood fibre material, comprising the following steps: a) delaminating wood particles, that are large and optionally pre-treated with chemicals and/or water, into modified wood particles; b) grinding the modified wood particles produced in step a) in one or a number of refiners; c) and optionally treating the material produced in step b) withoxidative or reductive bleaching agents. The method is characterised in that step a) and/or step b) are carried out in the presence of a composition Z, said composition Z containing one or a number ofthe following components (Z1) to (Z3): a salt of dithionous acid H2S2O4 (Z1); a compound (Z2) that generates the dithionous acid or a derivate of the dithionous acid; a salt of sulphurous acid (sulphite) plus sodium tetrahydridoborate (Z3); and optionally additives (Z4). 本发明涉及种生产漂白木纤维材料的方法，包括如下步骤：a)将任选用化学品和/或水预处理的较大木颗粒脱层成改性木颗粒；b)将获自a)的改性木颗粒在个或多个精磨机中研磨；和c)任选用氧化性或还原性漂白剂处理在步骤b)中获得的茎。所述方法的特征在于，步骤a)和/或步骤b)在组合物Z存在下实施，所述组合物Z包含种或