GB2265379A - Fabric washing detergents - Google Patents

Abstract

A detergent composition in semi-solid form comprises a non-soap surface active material, a precipitating builder and a hydrotrope, and may contain an amount of water-soluble phosphate containing sequestering builder is less than 30% of that of the precipitating builder. Such compositions have improved lather characteristics. The surface active material may be fatty acyl ester sulphonate, alkyl aryl sulphonate, or primary alkyl sulphate. The builder may be sodium carbonate, and the hydrotrope is urea or glycerol.

Description

DETERGENT COMPOSITION This invention relates to detergent compositions in semisolid form, that is to say a gel, cream or paste. Such a detergent form is sufficiently solid that it cannot be poured at ambient temperatures and it coheres together in a mass which can, however, be deformed by hand. Thus, this form is distinct from liquids, powders and shaped solid forms, such as bars.

Semi solid detergent compositions may be used for washing fabrics. Indeed such a detergent form is already marketed in some countries.

For use in fabric washing the semi-solid composition may be rubbed directly onto the fabric and it may, therefore, be referred to as a direct application product. In such a washing process the concentration of the composition on the fabric is, at least temporarily, very high.

The current practice of formulating detergent products to be used for washing fabrics by agitation in a aqueous wash liquor involves ensuring that water hardness and lather are controlled, for example by the use of sequestering builders such as water soluble salts of tripolyphosphate and pyrophosphate.

In contrast, for direct application products, the ability of the product to lather during use is an important factor. In many cases, speed of generation and character, that is appearance and stability, of the lather are the properties by which the performance of such a product is judged. Lather also acts as a lubricant for the fabric being washing, making rubbing thereof easier.

It has now been found that detergent compositions in semisolid form with improved lather characteristics may be formulated based on the combination of one or more surfactants, a lather boosting additive and a precipitating builder.

The present invention accordingly provides a detergent composition in semi-solid form comprising: a) a non-soap surface active material; b) a precipitating builder, in an amount such that its anhydrous weight is at least 5% by weight of the composition; and c) a lather boosting additive selected from water soluble non-micelle forming and weakly micelle forming materials, in an amount from 1 to 5% by weight of the composition; and in which the total amount of water soluble phosphate containing sequestering builder is less than 30% by weight based on the amount of precipitating builder in the composition.

The surface active material is a material selected from anionic, nonionic, amphoteric, betaine, zwitterionic, cationic actives and mixtures thereof. Many suitable actives are commercially available and are described in the literature, for example, in "Surface Active Agents" and Detergents", Volumes I and II, by Swartz, Perry and Berch. Non-soap anionic surface active materials will generally be preferred in the compositions of the invention.

Although soap may be included it may inhibit lather formation and, therefore, the composition of the invention is preferably substantially free of soap. If present, the amount of soap should be less than 2% by weight of the composition.

Anionic surface active materials which are particularly suitable for use in the composition of the invention include: alkyl benzene sulnhonates of formula:

ii) primary alcohol sulphates of formula: R O SO3 M and/or iii) fatty acyl ester sulphonate of formula

in which R is a primary alkyl group, preferably having 10 to 18 carbon atoms; R' is a primary alkyl group preferably having 1 to 4 carbon atoms; and M is a cation such that the surface active material is water soluble. Other surface active material which may be used include alkane sulphonates; secondary alcohol sulphates; olefin sulphonates; and ethoxylated alcohol sulphates. If a nonionic detergent active is used, it will generally be an ethoxylated alcohol.

Preferably the precipitating builder will be a material which forms a calcium salt which is substantially insoluble in water. Preferred materials include water soluble alkali metal carbonates, for example sodium or potassium carbonates or a mixture thereof.

Water soluble phosphate containing sequestering builders which should preferably be excluded from the composition include alkali metal orthophosphate, pyrophosphate and tripolyphosphate.

Without being bound by theory, it is believed the lather boosting additive functions by increasing the tolerance of the surface active material to precipitation by electrolytes.

By "weakly micelle forming material" is meant a material which has little tendency to form aggregates of molecules in dilute aqueous solution.

Preferred lather boosting additives include urea, substituted ureas, short chain alkyl benzene sulphonates such as sodium toluene sulphonate and mixtures thereof.

Urea is the more preferred additive.

The detergent composition of the invention preferably contains, based on the total weight of the composition, from 15 to 45% by weight of a non-soap surface active material; a precipitating builder in an amount such that its anhydrous weight is 5 to 40%; more preferably at least 10% by weight, most preferably 15 to 25%; and 1 to 5% by weight of a lather boosting additive.

The composition of the invention may also contain conventional detergent additives in amounts normally present in such detergent compositions. Such additives include antiredeposition agents such as sodium carboxymethyl cellulose; inorganic salts such as sodium sulphate and sodium bicarbonate; fillers such as talc and kaolin; colouring materials; fluorescers; photobleaches silicates such as alkaline sodium silicate germicides; enzymes; opacifiers; humectants such as glycerol; perfumes and bleaches. Also included amongst these optional additives are structuring agents such as aluminosilicate, amorphous aluminosilicate; and crystalline zeolites also commonly used as detergency builders.The aluminosilicate is desirably formed in situ in the composition by incorporating a soluble aluminium salt such as aluminium sulphate in the composition and also sodium silicate, as described in British Patent Specification 2 099 013 incorporated herein by reference.

Particularly preferred additives are humectants and, in particular, glycerol, added to reduce efflorescence; and partial inorganic salts, such as sodium bicarbonate, added to ameliorate any harshness to the skin of the user of the compositions of the invention.

Compositions of the invention may conveniently be prepared by adding the non-soap surface active material, precipitating builder, lather boosting additive and any other optional conventional detergent additives to water and mixing the resulting mixture.

A suitable procedure is to heat the water and dissolve in it builder and other solid electrolyte (if used) while mixing under conditions of high shear. When these components have dissolved, the surface active material is added, followed by the additives required for structuring (if used). Thereafter, and if used, the filler, humectant, brightener and any other remaining conventional additives, with the exception of the bleach and enzyme, are added. Finally the lather boosting additive, and, if used, bleach and enzymes are added.

The surface active material should be fully neutralised before the lather boosting additive is added, to avoid decomposition of the latter during manufacture.

The invention is further illustrated by the following nonlimiting Examples, in which the percentages are by weight of the composition.

In use, fabrics to be washed are contacted with a composition according to the invention or with a liquor formed by dilution of the composition and then rinsed.

Example A number of detergent creams were prepared by the procedure described above using raw materials carefully sieved to exclude particles larger than 100 microns.

Their formulations are set out in the following table: Table 1 Formulation 1 2 3 4 Component Branched alkyl (C12) 22 22 benzene sulphonate Primary alcohol - - 22 22 (coconut) sulphate Sodium carbonate 20 5 15 5 Sodium pyrophosphate (STP) - 6 - 6 Urea 1 1 1 1 Glycerol - - 1 1 Water/minors ----------- to 100 --------- Assessment of the stability of lather was determined by the following procedure: A 1 gm sample of a cream was dissolved in 1 litre of demineralised water. Commercially available kaolin clay was added to the water to give a soil concentration of 1 gm/litre. The temperature of the resulting solution was 250C. It was agitated by hand for 30 secs and then allowed to stand for 20 minutes. During this time the volume (measured in litres) of lather generated and remaining on the surface of the wash solution was measured periodically.

The speed of generation of lather during hand washing was determined by the following procedure: A 0.9 gm sample of a cream was applied evenly to a polyester/cotton test cloth soiled with a mixture of clay and synthetic sebum. The test cloth was washed by hand rubbing (for various lengths of time) the cream onto the test cloth, which was laid across a corrugated wash board.

The maximum wash time was 60 seconds. Thereafter the lather generated was collected in a measuring cylinder and the height of lather measured in mm.

Example 1 In this example the lather stability of a cream according to the invention (Product 1) was compared with a conventional cream formulation containing a high level of sodium pyrophosphate (Product 2). The results in table 2 demonstrate the product according to the invention has improved lather stability compared to the conventional product.

Table 2 Lather Volume (litres) Standing Time (mins) Product 1 Product 2 0 75 72 2 49 45 5 40 24 10 28 8 15 20 4 20 14 2 Example 2 In this example the speed of generation of lather of a formulation according to the invention (Product 1) was compared to a conventional cream formulation (Product 2).

The results in table 3 demonstrate that the speed of generation of the lather is faster for a product according to the invention than for a conventional product.

Table 3 Lather Height (mm) Washing Time (secs) Product 1 Product 2 20 106 70 40 135 119 60 242 205 Example 3 This example demonstrates the improvement in lather stability of a composition according to the invention (Product 3) compared to a conventional cream composition (Product 4) is maintained when the branched chain alkyl benzene sulphonate is replaced by a primary alcohol sulphate (EMAL 10, a commercial coconut based PAS supplied by Kao).

Table 4 Lather Volume (litres) Standing Time (mins) Product 3 Product 4 0 74 70 2 52 48 5 47 42 10 42 38 15 38 36 20 34 29 Example 4 In this example the effect on lather stability of altering the ratio of sodium carbonate to sodium pyrophosphate in formulation 2 was examined.

Table 5 % Proportion Lather Volume (litres) Sodium Carbonate STPP after a standing time of 2 minutes 100 0 41 94 6 40 83 17 40 71 29 39 45 55 26 0 100 18

Claims (8)

1. CLAIMS 1. A detergent composition in semi-solid form comprising: a) a non-soap surface active material; b) a precipitating builder, in an amount such that its anhydrous weight is at least 5% by weight of the composition; and

   c) a lather boosting additive selected from water soluble non-micelle forming and weakly micelle forming materials, in an amount from 1 to 5% by weight of the composition; and in which the total amount of water soluble phosphate containing sequestering builder is less than 30% by weight based on the amount of precipitating builder in the composition.
2. 2. A detergent composition according to claim 1 comprising 15 to 45% by weight of a non-soap surface active material.
3. 3. A detergent composition according to claim 1 wherein the builder is a material which forms a calcium salt which is substantially insoluble in water.
4. 4. A detergent composition according to claim 3 wherein the builder is a water-soluble alkali metal carbonate.
5. 5. A detergent composition according to claim 1 wherein the lather boosting additive is selected from urea, substituted derivatives of urea, short chain alkyl benzene sulphonates and mixtures thereof.
6. 6. A detergent composition according to claim 1 further comprising aluminosilicate.
7. 7. A detergent composition according to claim 1 further comprising a humectant.
8. 8. A method of washing fabrics comprising contacting the fabric with a composition according to any one of the preceding claims, or a liquor formed by dilution of the composition followed by rinsing the fabric.