Patents by Inventor John David Withenshaw

John David Withenshaw has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6569286
    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.
    Type: Grant
    Filed: August 8, 2001
    Date of Patent: May 27, 2003
    Assignee: Warwick International Group Limited
    Inventors: John David Withenshaw, Jane Williams, Mark Ardern Chadwick, Neil Anthony Turner
  • Patent number: 6080710
    Abstract: A process for making a coated bleach component which may be incorporated into a detergent composition comprising hydrogen peroxide solution. The process includes the steps of dispersing the bleach component in a continuous liquid phase to form discrete islands of dispersed phase and subsequently forming a polymeric coating at the interface between the dispersed phase and the continuous phase. The coating formed is resistant to hydrogen peroxide solution and is removable when the liquid continuous phase is diluted with aqueous wash liquor. In this way particulate material which reacts with hydrogen peroxide can be incorporated into an aqueous detergent liquid which contains dissolved hydrogen peroxide, whilst maintaining stability.
    Type: Grant
    Filed: May 3, 1996
    Date of Patent: June 27, 2000
    Assignee: Warwick International Group Limited
    Inventors: John David Withenshaw, Mark Alexander France
  • Patent number: 5800755
    Abstract: 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.
    Type: Grant
    Filed: September 16, 1996
    Date of Patent: September 1, 1998
    Assignee: Warwick International Group Limited
    Inventors: John David Withenshaw, Mark Ardern Chadwick, William John Wilson