Method for the alkaline bleaching of pulp with a peroxyacid based oxygen bleaching species using an agglomerated bleach activator
First Claim
1. A process for the bleaching of wood and non-wood pulp comprising the steps of:
- a) adding an aliquot of agglomerate from a bulk solid dispensing means to a dilute solution of hydrogen peroxide, wherein the agglomerate comprises;
a bleach activator;
a peroxide soluble binder;
a dispersing system comprising a wetting agent which is low foaming and does not discolour on exposure to temperatures of up to 120°
C. and optionally a salt, which is highly soluble in hydrogen peroxide; and
wherein the amount of hydrogen peroxide is more than twice that which can react with the activator;
b) allowing the bleach activator to substantially completely react with the hydrogen peroxide in the presence of a sequestrant which is provided in the agglomerate and/or the dilute hydrogen peroxide to generate a peroxyacid based oxygen bleaching species in a bleaching solution;
c) adjusting the pH of the bleach solution by adding alkali; and
d) bleaching the pulp by contacting it with the bleaching solution under alkaline conditions.
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Accused Products
Abstract
Wood and non-wood pulp is bleached by: a) adding an aliquot of agglomerate from a bulk solids dispensing means, advantageously a hopper, to a dilute solution of hydrogen peroxide which is desirably agitated to keep the agglomerate in suspension, the agglomerate comprising: a bleach activator, advantageously tetraacetyl ethylene diamine (TAED); a peroxide soluble binder, preferably polyvinyl alcohol (PVOH); a dispersing system comprising a wetting agent which is a low foaming and does not discolour on exposure to temperatures of up to 120° C. and optionally a salt, preferably sodium acetate, which is highly soluble in hydrogen peroxide; and sequestrant which may additionally or alternatively be added directly to the hydrogen peroxide; b) allowing the TAED to substantially completely react with the hydrogen peroxide; c) adjusting the pH of the bleach solution by adding alkali, preferably caustic soda; and d) bleaching the pulp by contacting it with the bleaching solution under alkaline conditions.
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Citations
10 Claims
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1. A process for the bleaching of wood and non-wood pulp comprising the steps of:
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a) adding an aliquot of agglomerate from a bulk solid dispensing means to a dilute solution of hydrogen peroxide, wherein the agglomerate comprises;
a bleach activator;
a peroxide soluble binder;
a dispersing system comprising a wetting agent which is low foaming and does not discolour on exposure to temperatures of up to 120°
C. and optionally a salt, which is highly soluble in hydrogen peroxide; and
wherein the amount of hydrogen peroxide is more than twice that which can react with the activator;
b) allowing the bleach activator to substantially completely react with the hydrogen peroxide in the presence of a sequestrant which is provided in the agglomerate and/or the dilute hydrogen peroxide to generate a peroxyacid based oxygen bleaching species in a bleaching solution;
c) adjusting the pH of the bleach solution by adding alkali; and
d) bleaching the pulp by contacting it with the bleaching solution under alkaline conditions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
wherein R1CO is an acetyl group and L is a leaving group attached via an oxygen or a nitrogen atom to the C═
O carbon atom.
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10. A process for the bleaching of wood and non-wood pulp comprising the steps of:
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a) adding an aliquot of agglomerate from a bulk solid dispensing means to a dilute solution of hydrogen peroxide, wherein the agglomerate comprises;
a bleach activator;
a peroxide soluble binder including no more than 1.1% cellulosic material as a percentage of agglomerate;
a dispersing system comprising a wetting agent which is low foaming and does not discolour on exposure to temperatures of up to 120°
C. and optionally a salt, which is highly soluble in hydrogen peroxide; and
wherein the amount of hydrogen peroxide is more than twice that which can react with the activator;
b) allowing the bleach activator to substantially completely react with the hydrogen peroxide in the presence of a sequestrant which is provided in the agglomerate and/or the dilute hydrogen peroxide to generate a peroxyacid based oxygen bleaching species in a bleaching solution;
c) adjusting the pH of the bleach solution by adding alkali; and
d) bleaching the pulp by contacting it with the bleaching solution under alkaline conditions.
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Specification