US Patent 7731818 Process for deinking waste paper

The present invention relates to a process for deinking waste paper comprising treating the waste paper with a peroxide compound in an aqueous alkaline medium in the presence of a first polymer (A) comprising a Ca-binding polymer in the form of a polycarboxylate polymer and a second polymer (B) comprising a poly-alfa-hydroxyacrylic acid or a salt thereof or the corresponding polylactone, said process additionally comprising treating the waste paper with at least one non-ionic surfactant or with at least one combination of a non-ionic surfactant and a fatty acid or a salt thereof to promote ink detachment and/or ink removal.