Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Patent
1996-01-16
1999-04-06
Anthony, Joseph D.
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
510310, 510312, 25218627, 25218638, 25218622, C11D 339, C11D 718, C01B 1510
Patent
active
058918370
DESCRIPTION:
BRIEF SUMMARY
This Application claims priority under 35 U.S.C. .sctn.371 to a International Application Serial Number PCT/US94/07823 filed Jul. 1, 1994.
This invention relates to bleaching compositions comprising alkali metal percarbonate as an oxygen-releasing compound and alkali metal carbonate or bicarbonate particles. These bleaching compositions are useful as components of laundry detergent compositions, machine dishwashing compositions and bleach booster compositions, in particular laundry detergent compositions.
Bleaching compositions containing alkali metal percarbonate are known in the art. Percarbonate is an attractive perhydrate bleaching agent for use in bleaching compositions because it dissolves readily in water and is weight efficient. In laundry detergent compositions it is particularly useful because after giving up its available oxygen it provides a useful source of carbonate ions for detergency purposes and does not provide undesirable by-products.
The inclusion of percarbonate salts in bleaching 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.
Bleaching compositions containing percarbonate as a bleaching component usually also contain carbonate such as sodium carbonate. This acts to neutralise acidity released when the composition is added to water. Such acidity inhibits the performance of the percarbonate and may inhibit the performance of other components of the bleaching composition, for instance enzymes in the case of laundry detergent compositions. In the case of granular zeolite-built detergent compositions the carbonate acts also to facilitate processing of the zeolite-containing composition into granules.
However, the presence of carbonate particles can contribute to reduced storage stability of the percarbonate. During storage, in particular storage under cool conditions, carbonate particles can absorb moisture, which is released during storage in warm conditions, for instance at above 30.degree. C. In the resulting warm, moist atmosphere the storage stability of the percarbonate is reduced.
It has been attempted to solve this problem by coating the carbonate particles. However this is a complex and expensive process and may reduce the ability of the carbonate to absorb moisture; this moisture-absorption ability is an advantageous one, therefore to reduce it is not preferred.
According to the invention there is provided a particulate composition comprising: having a mean particle size of 250 .mu.m or greater.
It has been found that the use of particles of carbonate with the defined size results in greater storage stability of the particulate compositions of the invention whilst retaining the fast release of alkalinity in cold water necessary for good product performance.
The alkali metal carbonate or bicarbonate is preferably selected from sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate and mixtures thereof. Particularly preferred mixtures include mixtures of sodium carbonate with sodium bicarbonate, sodium carbonate with potassium carbonate and sodium carbonate with sodium bicarbonate and potassium carbonate.
The particles of carbonate and bicarbonate have a mean particle size of 250 .mu.m or greater, preferably 300 .mu.m or greater, more preferably 400 to 800 .mu.m. It is preferred that fewer than 20% of the particles have a particle size below 250 .mu.m and that fewer than 5% have a particle size below 150 .mu.m; more preferably fewer than 10% have a particle size below 250 .mu.m. It is also preferred that fewer than 20% of the carbonate or bicarbonate particles have a particle size greater than 1,000 .mu.m.
The mean particle size of the particles of carbonate and bicarbonate herein is determined by reference to a method involving choice of varied sizes of sieve through which the sample is attempted to be passed. The mean particle size of a sample is given by the diameter of sieve through which half of the mass of the sa
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Baillely Gerard Marcel
Sorrie Graham Alexander
Anthony Joseph D.
Bolam Brian M.
Robinson Ian S.
The Procter & Gamble & Company
Zerby Kim William
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