Process for bleaching cellulose with organic peracid
AssigneeDegussa AG
InventorsHorst Kruger, Wilhelm Berndt, Hans U. Suss
Life of this patent
Estimating the term…
Abstract
Cellulose is bleached by means of an organic peracid in the acid region and subsequently by means of peroxide in the alkaline region. As peracid there is employed an acid which is produced from the corresponding carboxylic acid by reaction with hydrogen peroxide in the presence of a mineral acid. The peroxide bleaching step which follows the peracid bleaching step is carried out after there is added the necessary amount of aqueous alkali solution for carrying out the peroxide bleaching step of the pulp without intermediate washing of the cellulose. A further addition of peroxide is not carried out.
Claims8
A process for the bleaching of cellulose using peroxide in the alkaline range and an organic percarboxylic acid in the acid range werein a bleaching step with peroxide follows the bleaching step with the percarboxylic acid comprising (1) carrying out the bleaching with aqueous percarboxylic acid containing 5 to 40 weight % of percarboxylic acid and 10 to 50 weight % hydrogen peroxide, said percarboxylic acid having been produced from an organic carboxylic acid having a concentration of 50 to 100 weight % by reaction with 30 to 90 weight % hydrogen peroxide in the presence of a mineral acid at a temperature between 20.degree. and 100.degree. C. and (2) adding to the cellulose immediately after the percarboxylic acid bleaching step and without an intermediate washing an amount of aqueous alkali needed for carrying out an alkali bleaching step with said peroxide and then carrying out the peroxide bleaching without further addition of peroxide with said hydrogen peroxide.
Dependencies are inferred from the claim text.