Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2002-08-19
2004-02-24
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
Reexamination Certificate
active
06696400
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a granular composition for use as speckles in a particulate laundry detergent composition comprising photobleach.
BACKGROUND AND PRIOR ART
Photobleaches are often added to detergent laundry powders to provide bleaching of the washed fabrics to improve their visual appeal. The most common and simplest way of incorporating them into detergent powders is to add them to the slurry prior to spray drying of the base powder. However some of the photobleach may be lost due to degradation and evaporation in the spray drying process. Furthermore, there is a well-known problem of staining of the washed fabric due to the photobleach.
EP 119 746A (Unilever) discloses spraying a solution or suspension of a Zn or Al phthalocyanine sulphonate photobleach onto a detergent base powder subsequent to the spray drying process.
WO 99 51714A (Unilever) discloses a coloured photobleach speckle composition giving reduced staining wherein the carrier is an &agr;-hydroxy organic acid, preferably citric acid, with a water-soluble barrier material and a flow aid e.g. silica. The composition is claimed to provide reduced fabric staining.
DE 3 430 773A (Ciba Geigy) discloses a washing powder additive in speckle form which contains a photobleach, an inorganic carbonate and an acid. Effervescence action generated by the reaction between the carbonate and the acid is claimed to keep the speckles at the surface of the wash liquor and reduce staining of the washed fabrics.
U.S. Pat. No. 3,931,037 (Procter & Gamble) discloses a colourless granular composition comprising a pale-coloured photobleach granule made by the dry-mixing of a phthalocyanine photobleach particle and a granular material (e.g. sodium tripolyphosphate or spray-dried detergent base powder) to which a liquid (e.g. water) is added.
U.S. Pat. No. 4,762,636 (Ciba-Geigy) discloses a process for making floating speckles and preferably comprise an active substance such as a phthalocyanine. The bulk density of the speckles is in the range of from 50 to 500 g/l, preferably 200 to 350 g/l.
SUMMARY OF INVENTION
The present inventors have surprisingly found that a speckle composition with a layering system can deliver photobleach to the fabric with little or no staining.
In a first aspect, the present invention provides a granular composition for use as speckles in a particulate laundry detergent composition comprising a porous granular carrier, at least 0.01 wt % photobleach based on the active ingredient, the composition being layered with a finely divided high carrying capacity particulate material and/or a water-soluble material.
In a second aspect, the present invention provides a particulate laundry detergent composition which comprises surfactant, optionally builder, and from 0.05 to 10 wt % of speckles which are a granular composition as defined above.
In a third aspect, the present invention provides a process for making a granular composition for use as speckles in a particulate laundry detergent composition, which comprises the steps of:
(i) mixing a liquid photobleach with a porous carrier; followed by
(ii) layering with a finely divided, high liquid carrying capacity particulate material and/or a water-soluble material.
In a fourth aspect, the present invention provides the use of a granular composition layered with a finely divided high carrying capacity particulate material and/or a water-soluble material as speckles in a particulate laundry detergent composition.
DETAILED DESCRIPTION
The Speckles
The granular compositions of the present invention are intended to be used as speckles in particulate laundry detergent compositions. It is important that such speckles comprise at least 0.01 wt % of the photobleach active ingredient. It is also believed that reduced staining can be achieved if the photobleach is locked into the carrier by at least one coating layer. The composition is layered with a finely divided high carrying capacity particulate material and/or a water-soluble material. Preferably the water-soluble material is a water-soluble polymer. Preferably the composition is layered with both a water-soluble material and a finely divided high carrying capacity particulate material. For an even greater effect the composition contains at least two layers of each material.
The finely divided high liquid carrying capacity particulate material preferably has a dibutyl phthalate carrying capacity of at least 40 ml/100 g, preferably at least 50 ml/100 g and even more preferably at least 60 ml/100 g. In order that the speckles may provide effective delivery of photobleach for the whole of the detergent powder for which they are intended to be incorporated it is preferred that they comprise at least 0.05 wt % photobleach based on the active ingredient, preferably at least 0.1 wt %.
The carrier for the speckles is preferably light sodium carbonate (light soda ash). Light sodium carbonate may be distinguished from other grades of particulate sodium carbonate primarily by bulk density and has a bulk density of from 500 to 700 g/l. The carrier for use in the present invention preferably has a bulk density of less than 800 g/l, more preferably less than 700 g/l, most preferably less than 600 g/l.
Although the carrier for the photobleach is of a relatively low density, the resultant granule for use as a speckle may have an increased bulk density due to its processing and still perform effectively as a delivery vehicle for the photobleach. Therefore, in one embodiment of the invention the granular composition has a bulk density of greater than 500 g/l, preferably greater than 600 g/l, more preferably greater than 700 g/l, or even greater than 800 g/l.
Preferred photobleaches are phthalocyanine sulphonates, especially zinc phthalocyanine sulphonates, aluminium phthalocyanine sulphonates or a mixture of the two.
It is unnecessary to include ingredients which may cause effervescence, and hence it is preferred that the speckle is non-effervescent. However, inclusion of effervescence-generating ingredients is within the scope of the invention.
In a preferred embodiment the granular composition for use as speckles has a number average particle size of less than 400 microns, preferably less than 300 microns. This can improve the solubility and thereby decrease staining tendencies still further.
The Process for Making the Speckles
The process of manufacture of the speckles according to the present invention comprises the steps of:
(i) mixing a liquid photobleach with a porous granular carrier; followed by
(ii) layering with a finely divided, high liquid carrying capacity particulate material and/or a water-soluble material.
Preferred high liquid carrying capacity particulate materials are zeolite and/or silica.
Preferably step (ii) comprises layering with both a finely divided, high liquid carrying capacity particulate material and a water-soluble material.
It is preferred that the process is followed by a third step involving further layering with a finely divided, high liquid carrying capacity particulate material and/or a water-soluble material, preferably both together.
In any or all of the process steps the water-soluble material is preferably a water-soluble polymer.
A particularly advantageous process is wherein step (i) comprises atomising and spraying the liquid photobleach onto the carrier.
The Particulate Laundry Detergent Composition
Detergent compositions of the present invention comprise surfactant and optionally builder. They also contain from 0.05 to 10 wt %, preferably from 1 to 5 wt %, of speckles as described above. It is preferred that the compositions comprise from 5 to 60 wt % surfactant and from 10 to 80 wt % builder.
In a particularly advantageous embodiment the whole composition is coloured blue, however the speckles contained within it are a darker shade of blue than the rest of the composition. In another particularly advantageous embodiment the bulk of the powder is coloured white and the speckles are coloured blue.
Photobleach may be present in both the speckles and the composition as
Bonelli Juan Jose
Bonfa Marcio Henrique Perissinotto
Gusmao Paulo-Enrique De
Puelle Andrade Paulo Cesar
Gupta Yogendra N.
Mitelman Rimma
Petruncio John M
Unilever Home & Personal Care USA , division of Conopco, Inc.
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