Bleaching of cellulosic pulps using hydrogen peroxide
AssigneeThe Dow Chemical Company
InventorsRobert J. Michalowski, Steven H. Christiansen, Jimmy Myers, David A. Wilson
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Abstract
Bleaching of wood pulp is improved by the combination of a pretreatment of the pulp with a polyaminocarboxylic acid, e.g. ethylenediaminetetraacetic acid, prior to bleaching with an alkaline aqueous peroxide solution containing a stabilizing amount of an aminophosphonic acid derivative together with a polymer of an unsaturated carboxylic acid or amide or an alkylsulfonic acid substituted amide.
Claims41
In a process for bleaching wood pulp using hydrogen peroxide in an alkaline silicate-free aqueous system, the improvement which comprises the steps of (1) pretreating the pulp with a polyaminocarboxylic acid or salt thereof and (2) bleaching with hydrogen peroxide stabilized with
- (a) an aminophosphonic acid chelant or salt thereof and
- (b) at least one polymer of
- (i) an unsaturated carboxylic acid or salt thereof,
- (ii) an unsaturated carboxylic amide or
- (iii) an unsaturated carboxylic amide wherein the amide hydrogens are substituted with an alkylsulfonic acid group or salt thereof.
Dependencies are inferred from the claim text.