Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With oxygen or halogen containing chemical bleach or oxidant...
Reexamination Certificate
1999-02-01
2002-04-30
Einsmann, Margaret (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
With oxygen or halogen containing chemical bleach or oxidant...
C510S309000, C510S356000, C510S361000, C510S477000, C510S478000, C510S504000, C510S509000
Reexamination Certificate
active
06380144
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a detergent composition comprising high levels of perborate bleach and a tri- or multi protonic acid and alkali source. The detergent compositions are useful for laundry and dish washing methods.
BACKGROUND OF THE INVENTION
There is a trend amongst commercially available granular detergents towards higher bulk densities and towards granular detergent compositions which have a higher content of detergent active ingredients, such as bleach. Such detergents offer greater convenience to the consumer. The desire for such concentrated products ensures that the amount of filler materials are reduced and packaging materials will, ultimately, be disposed of
Amongst consumers there is also a need for detergents which provide improved bleachable stain removal. Therefore, in the recent past detergents have been developed which contain various types of bleaches, which can be incorporated at high levels.
Detergents, comprising high levels of bleach can lead to poor solubility properties arising from low rate of dissolution or the formation of gels, and thus to poor dispensing of the product, either from the dispensing drawer of a washing machine, or from a dosing device placed with the laundry inside the machine. This poor dispensing is often caused by gelling of particles, which have high levels of surfactant and especially perborate bleach, upon contact with water. The gel prevents a proportion of the detergent powder from being solubilized in the wash water which reduces the effectiveness of the powder. This is a particular problem at low water pressures and/or at lower washing temperature.
EP-A-0 639 637 discloses the replacement of perborate bleach with an alkali metal percarbonate to improve the dispensing profile and dissolution rate of a detergent. Citrate or mixtures of citrate with sulphate or carbonate can be used to coat the percarbonate bleach. EP-A-0 639 639 contains a similar disclosure in this respect.
The use of effervescence to improve the dispensability of granular materials has been used extensively in pharmaceutical preparations. The most widely used effervescent system in this respect is citric acid in combination with bicarbonate. This effervescent system has also been described for improving the dispersibility of pesticidal compositions for controlling water-borne pests, e.g. GB-A-2,184,946.
EP-A-0 534 525 discloses the use of particulate citric acid with a specified particle size range of 350 to 1500 microns.
U.S. Pat. No. 5,114,647 discloses a sanitizing composition comprising granules of alkali metal carbonate and aliphatic carboxylic acid of a particle size of 150 to 2,000 microns.
EP-A-0 333 223 discloses a bathing preparation comprising fumaric acid having an average particle size of 50-500 microns.
The Applicants have found that a problem of the poor dispensing of perborate bleach and particularly perborate monohydrate bleach, is the formation of a localized high concentration of bleach, which will contact the fabric. This can lead to fabric damage. This problem can especially be encountered with detergent compositions comprising high levels of perborate (monohydrate) bleach. However, these high concentrations are often required for an optimum bleachable stain removal.
The problem of poor dispensing may be exacerbated when high levels of surfactants are present. High levels of surfactants can lead to problems of solid detergent particles remaining in the washing machine and on washed clothes.
The Applicants now have found that this particular problem can be solved or reduced when there is provided a tri- or multi protonic acid, such as a citric acid and an alkali source, capable of producing a gas when reaction together. We have found that the addition of such an acid and an alkali source to a detergent composition, containing perborate bleach, improves the solubility and/or dispersion of the detergent and the perborate bleach therein, in the wash water and eliminates or reduces the problems of fabric damage by high concentrate bleach remaining in the washing machine and on washed clothes.
The improved dispensing of the perborate bleach amounts to an overall improved and more efficient performance and particularly improved bleachable stain removal.
Furthermore, it has been found that if the detergent compositions also comprise high levels of surfactants, such as anionic, cationic and nonionic surfactants, dispensing of surfactants can also be improved by the inclusion of these acid and an alkali sources (capable of producing a gas when reaction together), whilst the performance of the surfactants is maintained. This eliminates or reduces the problems of solid surfactant particles remaining in the washing machine and on washed clothes and it helps to minimize the formation of high concentrations of insoluble clumps. Furthermore, since the surfactants are more efficiently dispensed into the wash water, the overall performance of the surfactants is more efficient and an overall improved cleaning, stain removal and soil suspending can be achieved.
All documents cited in the present description are incorporated herein by reference.
SUMMARY OF THE INVENTION
According to the present invention there is provided a detergent composition comprising at least 13% or more of perborate component, and a tri- or multi protonic acid and an alkali source capable of reacting together to produce a gas. Preferably, one or more surfactants are present, selected from the group consisting of anionic, nonionic and cationic surfactants.
DETAILED DESCRIPTION OF THE INVENTION
Alkali Source
In accordance with the present invention, an alkali source is present in the detergent composition such that it has the capacity to react with the acid to produce a gas. Preferably this gas is carbon dioxide, and therefore the alkali is a carbonate, or a suitable derivative thereof.
The detergent composition of the present invention preferably contains from about 2% to about 75%, preferably from about 5% to about 60%, most preferably from about 10% to about 30% by weight of the alkali source. When the alkali source is present in an agglomerated detergent particle, the agglomerate preferably contains from about 10% to about 60% of the alkali source.
In a preferred embodiment, the alkali source is a carbonate. Examples of preferred carbonates are the alkaline earth and alkali metal carbonates, including sodium carbonate, bicarbonate and sesqui-carbonate and any mixtures thereof with ultra-fine calcium carbonate such as are disclosed in German Patent Application No. 2,321,001 published on Nov. 15, 1973. Alkali metal percarbonate salts may also be included in the detergent compositions and are also suitable sources of carbonate species and are described below in more detail.
The alkali source may also comprise other components, such as a silicate. Suitable silicates include the water soluble sodium silicates with an SiO
2
:Na
2
O ratio of from 1.0 to 2.8, with ratios of from 1.6 to 2.0 being preferred, and 2.0 ratio being most preferred. The silicates may be in the form of either the anhydrous salt or a hydrated salt. Sodium silicate with an SiO
2
:Na
2
O ratio of 2.0 is the most preferred silicate. Alkali metal persilicates are also suitable sources of alkali herein.
Other suitable sources will be known to those skilled in the art.
Tri-or Multi Protonic Acid
In accordance with the present invention, a tri- or multi protonic acid is present in the detergent composition such that the it is capable of reacting with the source of alkali in the presence of water to produce a gas.
The source of acidity may be any suitable tri-protonic or multi-protonic acid or mixtures thereof. Preferably, the acid source is a tri-protonic acid, most preferably this is a citric acid.
Derivatives include a salt or ester of the acid. The source of acidity is preferably non-hygroscopic, which can improve storage stability. However, a hydrated and especially monohydrate acidic source can be useful herein. The acid is preferably water-soluble.
The acid is preferably present at a level
Dressman Marianne
Einsmann Margaret
Miller Steven W.
The Procter & Gamble & Company
William Zerby Kim
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