GB2058823A

GB2058823A - Dishwashing compositions

Info

Publication number: GB2058823A
Application number: GB8029945A
Authority: GB
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1979-09-17
Filing date: 1980-09-15
Publication date: 1981-04-15
Also published as: GB2058823B

Abstract

A liquid detergent composition suitable for washing plates, dishes and saucepans containing (a) a calcium and/or magnesium sensitive anionic surfactant; (b) a source of calcium and/or magnesium ions; (c) a hydrotrope; (d) a defined alkyl phosphate or phosphonate or a salt thereof as an anti-resoiling agent; and (e) a pH controller in an amount sufficient to provide a pH in the composition of from 4-5.5. i

Description

SPECIFICATION Liquid dishwashing composition This invention relates to liquid detergent compositions for washing plates, dishes and saucepans.

We have filed a number of patent applications directed to compositions for washing plates, dishes and saucepans which contain an agent which reduces re-soiling of aluminium utensils such as saucepans. The agent in question is an alkyl phosphate ester, or an alkyl phosphonate or a salt thereof.

We have now discovered that not only are anti-resoiling agents useful in detergent compositions as disclosed in our British Patents Nos. 1,315,363, 1,395,031, 1,447,228 and 1,455,823, but certain of them are also in liquid detergent compositions formulated for use in concentrated solutions. Such compositions contain, as essential components, a calcium and/or magnesium sensitive anionic surfactant, a source of calcium and/or magnesium ions, and a hydrotrope.

In accordance with the present invention there is provided a liquid detergent composition comprising (a) a calcium and/or magnesium-sensitive anionic surfactant; (b) a source of calcium and/or magnesium ions; (c) a hydrotrope; (d) a C,0~,5 alkyl phosphate ester or a CXO-5 alkyl phosphonate containing a maximum of 3 moles of ethylene oxide per mole of phosphate ester or phosphonate; and (e) a pH controller in an amount sufficient to provide a pH in the composition of from 4-5.5.

Suitable calcium and/or magnesium-sensitive anionic surfactants, which may be present in amounts of from 5 to 45%, preferably 10 to 20% by weight, are CrO-t4 alkyl benzene sulphonates, C1215 primary or secondary alkyl sulphates, C,3~,8 sulphonates, C"~,8 alpha and random olefine sulphonates and Ca s alcohol ether sulphates containing up to 3 moles of ethylene oxide per mole of alcohol sulphate. These surfactants will normally be present as their sodium/potassium/magnesium/ammonium or substituted ammonium salts. Mixtures of any of these compounds may also be used.

Nonionic surfactants may also be present in admixture with the above calcium and/or magnesium/sensitive anionic surfactants. Examples of suitable nonionic surfactants are C8C22 alcohol ethoxylates containing from 6 to 24 moles of ethylene oxide per mole of alcohol, and alkanolamides such as coconut alkanolamides. These nonionic surfactants may be present in amounts of from 2 to 20% by weight.

Any water-soluble salt of calcium or magnesium can be used as the source of calcium or magnesium ions provided that it is physiologically and environmentally acceptable. Examples of suitable salts are calcium chloride and magnesium sulphate. Magnesium salts of sulphonic acids, such as magnesium toluene sulphonate may also be used. The salts should be present in the compositions of the invention in an amount of from 1 to 5% by weight.

The third essential component of the compositions of the invention is a hydrotrope. The hydrotrope can be present in amounts from as little as 2% when urea or sodium toluene sulphonate is used to as much as 20% when ethanol or propanol is used. When magnesium toluene sulphonate or a similar magnesium salt is used as the source of magnesium ions the toluene sulphonate counter-ion should be considered as part of the hydrotrope for the purposes of determining how much hydrotrope is present in a given composition.

It has been found that alkyl phosphate esters and alkyl phosphonates are most effective in imparting anti-resoiling effects to the dishwashing liquids of the invention when the chain length of the alkyl residue is in the range C,,--C,,. Also it has been found that phosphate esters and phosphonates which are either unethoxylated or, if ethoxylated, then contain a maximum of 3 moles of ethylene oxide per mole of phosphate or phosphonate are most effective.

Preferred compounds are the phosphate esters of C,OCas primary alcohols and most preferred are the C12-C15 primary alkyl phosphates.

The pH controller is essential to the compositions of the invention if precipitation of calcium and/or magnesium phosphate is to be avoided. While simple acids such as hydrochloric acid can be used, it is much preferred to use a buffering agent such as a weak acid. Examples of suitable acids are acetic, propionic, citric and lactic acids. The precise amount of such an acid which will be necessary to achieve and retain a pH of from 4-5.5 will be dependent upon the alkalinity of the other components used in the composition. The pH of the composition can be measured using a standard technique and adjustments made by adding acid or alkali as appropriate.

Optional components may be present in the compositions in conventional amounts. Such components include, but are not confined to, colourants, perfumes and natural extracts such as citrus juices and opacifiers.

The invention will be further illustrated in the following Example.

EXAMPLE A number of liquid dishwashing compositions having the general formulation shown below and in Table 1 was prepared: % by weight Sodium C12 alkyl benzene sulphonate 12.0 Magnesium sulphate 7H2O 1.5 Urea 7.0 Phosphate ester anti-resoiling agent (see Table 1) 0.2 Water balance to 100 The pH of the composition was adjusted to pH 5 with hydrochloric acid and ammonium hydroxide.

A clean aluminium tile was scrubbed with a nylon fleece abrasive scrubbing head on a scrubbing machine for a standard number of scrubs under the surface of an aqueous solution. The solution contained 10% by volume of one of the dishwashing liquids above in 40 hard water. Following rinsing and drying the tile was then soiled with 1 ml of a 1:1 mixture of hen's egg and cow's milk and was heated to 2500C for 45 seconds.

After cooling, the tile was washed on the scrubbing machine with a soft towelling scrubbing head under the surface of a rinse water bath.

The number of scrubs required to remove the baked-on soil was recorded and the results are shown in Table 1.

TABLE 1 No. of scrubs Phosphate ester required to clean None 560 C,2~,5 primary alkyl phosphate 30 C,2~,4 primary alkyl phosphate 30 Ca 5 secondary alkyl phosphate 3EO 100 C16~18 secondary alkyl phosphate 150 Oleyl phosphate 3EO 350 The Table illustrates the effect of treating an aluminium slide with a dishwashing liquid containing an anti-resoiling agent in accordance with the invention, and the example demonstrates the superior effectiveness of alkyl phosphates containing from 10-1 5 carbon atoms in the alkyl group, as compared with ethoxylated alkyl phosphates and longer chain alkyl phosphates, although both of these latter compounds give improvements of liquids containing no phosphate at all.

Claims

1. A liquid detergent composition comprising (a) a calcium and/or magnesium-sensitive anionic surfactant; (b) a source of calcium and/or magnesium ions; (c) a hydrotrope; (d) a C,0~,5 alkyl phosphate ester or a C10~15 alkyl phosphonate containing a maximum of 3 moles of ethylene oxide per mole of phosphate ester or phosphonate; and (e) a pH controller in an amount sufficient to provide a pH in the composition of from 21 5.5.

2. A liquid detergent composition according to claim 1 comprising from 10 to 20% by weight of the anionic surfactant.

3. A liquid detergent composition additionally comprising a nonionic surfactant in an amount of from 2 to 20% by weight.

4. A liquid detergent composition according to any one of the preceding claims wherein the source of calcium and/or magnesium ions comprises magnesium sulphate, magnesium chloride, magnesium sulphonate or a mixture thereof.

5. A liquid detergent composition according to any one of the preceding claims wherein the hydrotrope comprises urea or sodium toluene sulphonate.

6. A liquid detergent composition according to claim 6 wherein the hydrotrope comprises magnesium toluene sulphonate.

7. A liquid detergent composition according to any one of the preceding claims comprising from 0.1 to 5% by weight of the alkyl phosphate ester or alkyl phosphonate.

8. A liquid detergent composition according to any one of the preceding claims wherein the pH controller comprises acetic acid, propionic acid, citric acid or lactic acid or a mixture thereof.

9. A liquid detergent composition according to any one of the preceding claims wherein the pH controller comprises ammonium chloride.

10. A liquid detergent composition comprising an alkyl phosphate ester or an alkyl phosphonate, substantially as hereinbefore described in the example.