Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Specific organic component
Reexamination Certificate
1999-02-26
2001-11-06
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Specific organic component
C510S117000, C510S276000, C510S445000, C510S477000, C510S509000, C510S345000, C510S444000, C510S446000
Reexamination Certificate
active
06313086
ABSTRACT:
TECHNICAL FIELD
The present invention relates to preferably a low density detergent composition containing sulphate, an acid dispersing aid and an alkali source, which is suitable for use in laundry washing methods.
BACKGROUND OF THE INVENTION
Detergent compositions, especially low density detergent compositions often contain high levels of sulphates. A problem encountered with these detergents can be the poor solubility properties of one or more components in the detergent. A consequence of this in a typical washing process can be 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 can reduces the effectiveness of the powder. This is a particular problem at low water pressures and/or at lower washing temperatures.
The prior art teaches various ways to improve the solubility of high bulk density detergent compositions. WO95/14767 relates to the poor dispensing of high density, non-spray-dried detergent powders, and discloses the use of a citric acid salt which has a Rosin Rammler particle size of less than 800 microns. WO94/28098 discloses a non-spray-dried detergent powder comprising a combination of an ethoxylated primary C8-18 alcohol, an alkali metal aluminosilicate builder and 5 to 40wt % of a water-soluble salt of a citric acid.
The use of effervescence to improve the dispersability 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 dispersabality of pesticidal compositions for controlling water-bore pests, e.g. GB-A-2,184,946.
It has now been found that particularly in low density detergent compositions, comprising high levels of sulphate, poor dispersing can lead to insolubility/precipitation of certain components (present in the washing water) onto the fabrics in the wash and onto the washing machine. In particular, it has been found that calcium and magnesium carbonate and limesoaps, formed by the water hardness, can precipitate onto the fabric. It has been found that this can even occur when builders (which are traditionally employed in detergents to counter the adverse effect on detergency of water hardness ions) are present.
Without wishing to be bound by theory, the Applicants believe that this is due to increased ionic strength, due to the high level of sulphates present in the washing water. The Applicants have now found that this problem can be solved by the use of a specific dispersing aid. It has been found that the precipitation of various components, such as magnesium and calcium carbonates and lime soaps, can be reduced in a low density detergent composition containing sulphate, an alkali source and incorporating a dispersing aid which is an acid source, can react with the alkali source to produce a gas, and which can also act as a water-soluble dispersant or builder material.
It is believed that the reaction of the acid source and the alkali source which produces gas (preferably carbon dioxide) firstly helps the dispersion and dispensing of the detergent, reducing deposition of (detergent) components on fabrics and the machine. In addition, builder materials will be dispensed more effectively so that calcium and magnesium ions are rapidly contacted with builder material, thereby quickly and effectively reducing the free calcium and magnesium in the water so that the formation of undesirably precipitates is substantially reduced. Furthermore, once in the wash water acid is de-protonated and the base form of the acid can act as a dispersant or builder, further reducing the free calcium and magnesium in the water and further reducing the formation of undesirable precipitates.
All documents cited in the present description are incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention relates to detergent compositions comprising sulphate, an acid dispersing aid and an alkali source wherein said acid dispersing aid and said alkali source are capable of reacting together in the presence of water to produce a gas. The ratio of sulphate to acid dispersing aid is 13.5:1 or less, or the level of acid dispersing aid is at least 1.5% by weight of the detergent composition. Preferably the detergent composition is a low density detergent composition.
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the invention there is provided a detergent composition comprising at least 15% by weight of a sulphate salt, an acid dispersing aid and an alkali source wherein said acid dispersing aid and alkali source are capable of reacting together in the presence of water to produce a gas, and wherein the weight ratio of sulphate salt to said acid dispersing aid is from 13.5:1 or less.
According to a second aspect of the invention there is provided a detergent composition comprising at least 15% by weight of a sulphate salt, an acid dispersing aid and an alkali source wherein said acid dispersing aid and alkali source are capable of reacting together in the presence of water to produce a gas, and wherein the level of acid dispersing aid is at least 1.5% by weight of the detergent composition.
Preferably the gas produced is carbon dioxide, and therefore the alkali source is preferably bicarbonate or carbonate.
In accordance with the invention the acid dispersing aid, which is capable of reacting with the alkali source to produce a gas, is preferably capable of building and/or dispersing free ions such as calcium and magnesium ions, present in the wash.
The granular detergent compositions in accordance with the present invention generally have a bulk density of at least 500 g/liter, preferably less than 850 g/liter more preferably from 600 g/liter to 750 g/liter.
Sulphate Salt
In the present invention the ratio of sulphate salt to the acidic dispersing aid is preferably from 12:1 to 1:1, most preferably from 11:1 to 2:1.
The sulphate salt can be present in the detergent composition in any form, preferably it is an inorganic sulphate salt, such as sodium sulphate, magnesium sulphate, ammonium sulphate or mixtures of various forms of sulphate. The sulphate preferably is substantially anhydrous, (i.e. generally no greater than 50% by weight of the sulphate salt containing water, preferably no greater than 25%, more preferably no greater than 15%, most preferably no greater than 10%), preferably it is anhydrous sodium sulphate. This is preferably combined with a small amount of magnesium sulphate, preferably of from 0.2% to 5% by weight of the composition.
Acid Dispersing Aid
The acid dispersing aid is a component capable of reacting with the source of alkali in the presence of water to produce a gas.
In the first aspect of the present invention the ratio of sulphate salt to the acid dispersing aid is 13.5:1 or less, more preferably from 12:1 to 1:1, most preferably from 11:1 to 2:1. The acid dispersing aid is preferably present at a level of from 0.05% to 25%, more preferably at a level of 0.5% to 15%, even more preferably of from 1% to 10%, even more preferably from 1% to 7%, most preferably of from 2% to 5% by weight of the detergent composition.
In the second aspect of the invention the level of the acid dispersing aid is at least 1.5% or more, preferably from 2% to 7% by weight of the composition.
Preferably, the detergent composition comprises at least 1.5% by weight of acid dispersing aid and 20.25% by weight of sulphate salts, in a ratio of sulphate salt to acid dispersing aid is from 13.5:1 or less.
In accordance with the invention the acid dispersing aid, which is capable of reacting with the alkali source to produce a gas, is preferably capable of building and/or dispersing free ions such as calcium and magnesium ions, present in the wash.
Preferably, 80% or more of the acid dispersing aid has a particle size in the range of from about 150 microns to about 710 microns, with at least about 37% by weight of the acid source having a pa
Askew Stuart Clive
Sorrie Graham Alexander
Dressman Marianne
Gupta Yogendra N.
Miller Steven W.
Mruk Brian P.
The Procter & Gamble & Company
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