D - Textiles – Paper – 21 – C
Patent
D - Textiles, Paper
21
C
D21C 9/10 (2006.01) D21C 9/16 (2006.01)
Patent
CA 2678466
Process for the bleaching of paper pulp Process for the bleaching of paper pulp in which : (a) an aqueous suspension of the paper pulp is first subjected to a chelating treatment with at leas t one aminopolycarboxylic acid, its salt or their mixtures in order to reduce at least partially the metallic ion, especially manganese, content of the suspension, (b) the aqueous suspension of the paper pul p thus obtained is subjected to a bleaching treatment with hydrogen peroxide in the presence of i. at least one poly-.alpha. -hydroxyacrylic acid, its salt or their mixtures, the function of which is to chelate at least partially iron present in the aqueous suspension, and ii. at least one aminopoly carboxylic acid, its salt or their mixtures, the function of which is to chelate calci um present in the aqueous suspension thereby improving the performance of the poly- .alpha.-hydroxyacrylic acid, its salt or their mixtures.
L'invention concerne un procédé de blanchiment de pulpe de papier, selon lequel: (a) on soumet d'abord une suspension aqueuse de pulpe de papier à un traitement de chélation avec au moins un acide aminopolycarboxylique, son sel ou des mélanges de ces derniers afin de réduire au moins partiellement la teneur en ions métalliques, en particulier en manganèse, de la suspension; (b) on soumet la suspension aqueuse de pulpe de papier obtenue à un traitement de blanchiment au peroxyde d'hydrogène en présence de i) au moins un acide poly-.alpha.-hydroxyacrylique, son sel ou des mélanges de ces derniers, qui ont pour fonction de causer la chélation au moins partielle du fer présent dans la suspension aqueuse; et ii) au moins un acide aminopolycarboxylique, son sel ou des mélanges de ces derniers, qui ont pour fonction de causer la chélation du calcium présent dans la suspension aqueuse, améliorant de la sorte la performance de l'acide poly-.alpha.-hydroxyacrylique, de son sel ou de mélanges de ces derniers.
Robic
Solvay (societe Anonyme)
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