Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Patent
1996-05-03
2000-06-27
Liott, Caroline D.
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
510309, 510372, 510375, 510376, 510445, 510475, 25218625, 25218641, C11D 754
Patent
active
060807105
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to detergent compositions, generally comprising bleach activator in which a detergent component, generally the bleach activator, is protected from its environment by a polymeric shell, of particular utility in liquid laundry detergents. Processes for making the composition are also described.
Laundry detergents conventionally contain a bleaching species. Chlorine bleaches are used in some instances, but peroxygen bleaches are in general preferred. Peroxygen bleaches include hydrogen peroxide itself, percarboxylic acids and inorganic persalts such as sodium perborate, percarbonate or persulphate. The inorganic persalts tend not to release the peroxygen bleaching species at low temperatures and it is conventional therefore to incorporate into the detergent liquor a bleach activator compound. Such compounds are generally N-acyl or O-acyl compounds which act as acyl donors in aqueous solution and which react with the bleach precursor (or bleach donor) compound to form a percarboxylic acid in situ.
The chemical reaction which takes place between the bleach precursor and the bleach activator compound is likely to take place whenever the two ingredients come into contact with one another in the presence of water. In order to avoid the premature reaction of the two species during storage of the detergent composition they therefore need to be kept separate from one another. Other components of the wash liquor also need to be kept separate from the bleach components to prevent degradation by those components during storage.
Various ways of rendering detergent components storage stable have been proposed. For bleach activators which are solids at room temperature it is usual for particulate activator to be granulated so that the activator particles are dispersed in a polymeric matrix to form granules. Granulating binders may be synthetic or natural polymers or their derivatives or mixtures of these. In general the binder should be soluble in alkaline wash liquor environments. Methods of granulating activators such as tetraacetyl ethylene diamine are described in our earlier specifications nos. EP-A-0,238,341 and EP-A-0,468,824.
Other ways of formulating bleach activators, including activators which are liquid at room temperature involve formulating them with molten surfactants, especially anionic and nonionic surfactants or fatty acids or poly(alkylene oxy) polymers. The activator may be formulated by spraying molten binder onto a moving bed of particulate bleach activator, by making a blend of molten binder and bleach activator and then shaping it, for instance by spray cooling, extrusion and chopping, or bleach activator may be granulated using inorganic binders, such as polyphosphate compounds.
There is a particular difficulty in formulating bleach activator in a form which will be storage stable in a liquid laundry detergent composition. Although suggestions have been made to incorporate bleach activator compositions into liquid detergents, the storage stability tends to be inadequate, the activator reacting prematurely with the bleach precursor to form oxygen gas in the container. In EP-A-0,385,522 a liquid laundry detergent with improved storage stability is described. The stability is estimated by determining the volume increase due to formation of gas bubbles. The storage stability is said to be achieved by structuring the liquid continuous phase. In that specification it is also proposed to encapsulate bleach particles as described in EP-A-0,294,904. It is also suggested to load the continuous liquid phase of the liquid detergents with electrolyte and to maintain a relatively low pH in the composition. The bleach precursor was either hydrogen peroxide, in solution in the continuous phase, or sodium perborate mono- or tetra-hydrate. None of the specific examples contained bleach activator.
In EP-A-0,356,239 and the CIP of the corresponding U.S. application, U.S. Pat. No. 5,324,445, there are described ways of formulating enzymes for inclusion in liquid detergent concentrates.
In
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France Mark Alexander
Withenshaw John David
Liott Caroline D.
Warwick International Group Limited
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