Patent ID: 7754048
Filing Date: 2010-07-13
Classification: D21C

Abstract:
1. A process for bleaching a cellulosic fibre material with a peroxide compound in an aqueous alkaline medium, comprising a bleaching step wherein a) a stable polymer solution comprising a first polymer (A) comprising a homopolymer of acrylic acid, methacrylic acid or maleic acid, or a copolymer of acrylic acid and/or methacrylic acid with an unsaturated dicarboxylic acid, and a second polymer (B) comprising a poly-alpha-hydroxyacrylic acid or a salt thereof, said polymer solution having a pH of at most 5, is added to a cellulosic fibre material, and b) thereafter adding a peroxide compound and an alkaline substance and carrying out the bleaching; wherein step (b) is carried out essentially immediately after the addition of the polymer solution to the cellulosic fibre material, without a washing step between steps (a) and (b).