| abstract |
The invention relates to a method for the bleaching of lignocellulosic fibers wherein lignocellulosic fibers are treated with at least one oxidizing bleaching chemical in aqueous solution. The invention also relates to the application of additives for bleaching lignocellulosic fibers and to the application of an aqueous solution containing at least one additive for bleaching lignocellulosic fibers. In the context of this paper, the term 'lignocellulosic fibers' includes all sorts and types of pulp like e.g. chemical and mechanical pulp, dissolving pulp or pulp prepared from waste paper but also natural fibers like cotton or flax fibers. The method for bleaching of lignocellulosic fibers according to the invention is characterized in that lignocellulosic fibers are treated with at least one oxidizing bleaching agent in aqueous solution in the presence of at least one additive which activates delignification and/or bleaching, the additive being selected among the phenanthrolines and/or polypyridyles. The method is applicable to all known oxidizing bleaching agents like oxygen, ozone and/or peroxo-chemicals or mixtures thereof especially for peroxo-chemicals which comprise hydrogen peroxide, sodium peroxide, perborates, performic acid, peracetic acid or caroic acid and/or salts thereof. |