Detergent compositions containing percarbonate and making proces

Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...

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25218626, 25218627, 25218642, 25218643, 510224, 510228, 510309, 510310, 510315, 510317, 510375, 510377, 510349, D06L 302, C11D 312, C11D 339, C11D 3395

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057804109

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/US94/07877 filed Jul. 13, 1994, published as WO95/02724 Jan. 26, 1994.


TECHNICAL FIELD

The present invention relates to detergent compositions containing percarbonate bleach, and a hydrophobic material such as hydrophobic silica at narrowly defined ratios to provide optimum bleach stability.
The invention also encompasses processes to make such compositions.


BACKGROUND OF THE INVENTION

The inorganic perhydrate bleach most widely used in laundry detergent compositions is sodium perborate in the form of either the monohydrate or tetrahydrate. However, an increased interest in other perhydrate salts is being observed, of which sodium percarbonate is the most readily available.
Detergent compositions containing sodium percarbonate are known in the art. Sodium percarbonate is an attractive perhydrate for use in detergent compositions because it dissolves readily in water, is weight efficient and, after giving up its available oxygen, provides a useful source of carbonate ions for detergency purposes.
The inclusion of percarbonate salts in laundry detergent compositions has been restricted hitherto by the relative instability of the bleach. In particular, percarbonate salts decompose rapidly when stored in a moist and/or warm atmosphere. It is known that acceptable storage characterisitics may however be obtained through the protection of the carbonate by coating the crystalline product, or by the inclusion of stabilizing agents during its manufacture, or both. A variety of suitable coating agents have been proposed including silicates and mixtures of inorganic sulphate and carbonate salts.
In W092/06163 are described percarbonate-containing compositions wherein the Equilibrium Relative Humidity as well as the level of heavy metal ion have to be carefully controlled to ensure percarbonate stability.
There is still, however, the need to improve storage stability of the percarbonate bleach, and to achieve this in all types of detergent compositions, including compositions made by the various making processes currently available.
The Applicants have however unexpectedly discovered that when a hydrophobic material selected from silica, talcs or waxes is used into the detergent compositions, in certain ratios to percarbonate particles of a determined size, and particularly when said hydrophobic material such as silica is used as dusting agent onto said percarbonate particles prior to their incorporation into the composition, the storage stability of the percarbonate is remarkably improved, in all types of compositions, including dishwashing compositions adapted for use in automatic dishwashing.
The use of silica as flow aid for detergent granules is known in the art, although the art usually does not distinguish between the different types of silica most advantageous for this purpose; in many cases, the use or precipitated silicas which are mainly hydrophilic, are described.
JP 61 069897, laid open 10th Apr., 1986 states that aluminosilcate, silicon dioxide, bentonite and clay having an average particle diameter of not more than 10 micrometers can be used as a surface modifier at a level of from 0.5% to 35%; Percarbonate is merely mentioned among the bleach ingredients.


SUMMARY OF THE INVENTION

The present invention relates to a granular detergent composition comprising an alkali metal percarbonate, characterized in that percarbonate has a mean particle size of from 250 to 900 micrometers, and that said compositions comprise a hydrophobic material selected from silica, talc, Zeolite DAY and hydrotalcit, in a weight ratio of alkali metal percarbonate to hydrophobic material of from 4:1 to 40:1, preferably 7:1 to 20:1.
Both laundry detergent compositions including laundry additives and automatic dishwashing compositions are encompassed by the term "detergent composition" herein. Making processes thereof are also described.


DETAILED DESCRIPTION OF THE INVENTION

Percarbonate
The laundry detergent or automatic dishwashing compositions herein typically contain from 1to 40%, pref

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patent: 2167997 (1939-08-01), Reichert
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patent: 5194176 (1993-03-01), Copenhafer et al.
patent: 5374368 (1994-12-01), Hauschild
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Derwent Abstract 91-011087/02 for JP 2-283,800, Nov. 1990.
Derwent Abstract 94-008705/02 for DE 4221736, Jan. 1994.

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