Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Heterogeneous arrangement
Patent
1996-01-16
1997-11-25
Lieberman, Paul
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Heterogeneous arrangement
510329, 510315, 510507, 510511, 252381, 252383, 252384, 252385, C11D 3395
Patent
active
056912960
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to detergent compositions containing percarbonate bleach; it provides a process for making such compositions which yields optimum bleach stability.
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. Our 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 characteristics 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 WO-92-06163 percarbonate-containing detergent compositions have been described, wherein the need for low Equilibrium Relative Humidity as well as low levels of heavy metal ions was disclosed.
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 partially hydrated crystalline aluminosilicate is used as a dusting agent onto the granules of detergent compositions containing the percarbonate bleaching agent, the percarbonate stability is remarkably improved, in all types of compositions.
U.S. Pat. No. 4,427,567 discloses a method for reconditioning caked detergent compositions wherein the caked composition is broken up to form a powder, and said powder is mixed/dusted with a dehydrated zeolite. The disclosed detergent compositions teach to limit the level of perborate or percarbonate at levels below 20% by weight, preferably less than 10% by weight.
JP 61 069897, laid open 10th Apr. 1986 states that aluminosilicate, silicon dioxide, bentonire 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. The preferred aluminosilicates are amorphous, and no preference for dehydrated material is given.
SUMMARY OF THE INVENTION
A process for making a granular detergent composition comprising the steps of adding to a detergent powder particles of percarbonate having a mean particle size in the range of from 250 to 900 micrometers and a powdery flow aid containing a partially hydrated crystalline sodium aluminosilicate having a moisture content of less than 15%, preferably from 5% to 12%.
DETAILED DESCRIPTION OF THE INVENTION
The process of the present invention is characterized by the addition to a detergent powder of particles of percarbonate, as well as a powdery flow aid, the two additions being conducted in either order, to produce a detergent composition.
By detergent composition herein, is meant laundry detergent composition, as well as automatic dishwashing composition or laundry additive.
The detergent powder herein is constituted of granular detergent components, each individual component having been prepared by processes such as agglomeration, compaction, encapsulation, grinding or spray-drying, said components being dry-mixed to obtain the detergent powder.
The granular components may be prepared and mixed
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Agar Joseph Thomas Henry
France Paul Amaat Raymond G.
Wilkinson Carole Patricia D.
Lieberman Paul
Ogden Necholus
Patel Ken K.
Rasser Jacobus C.
The Procter & Gamble & Company
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