Warwick International Group Limited

Mark Ardern Chadwick

John David Withenshaw

William John Wilson

Jane Williams

Neil Anthony Turner

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&deg; 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.

Method for the alkaline bleaching of pulp with a peroxyacid based oxygen bleaching species using an agglomerated bleach activator

An agglomerated active with controlled release comprising a particulate solid active material and a binder characterised in that the binder comprises from 0.02 to 5% by weight of a polyvinyl alcohol, based on the total weight of the agglomerate. The binder system simultaneously provides the desired hardness and release characteristics while maintaining a high level of actives. The active may be a bleach activator such as Tetraacetylethylenediamine. A process for manufacturing the agglomerate comprises the steps of mixing a particulate solid active material and optionally a portion of polyvinyl alcohol and optionally also a co-binder and then adding an agglomerating solution which optionally contains polyvinyl alcohol binder while mixing and agglomerating and drying the agglomerates to obtain an agglomerate with average particle size in the range 1-2000 microns wherein the agglomerate comprises from 0.02 to 5% by weight based on the total weight of the agglomerate of polyvinyl alcohol.

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Denbighshire, United Kingdom

Mark Ardern Chadwick