BACKGROUND OF THE INVENTION Conventional laundry detergent powders intended for the handwash contain a substantial level of anionic surfactant, most usually alkylbenzene sulphonate. Anionic surfactants are ideally suited to the handwash because they combine excellent detergency on a wide range of soils with high foaming. For high levels of oily soil, it is desirable to have a high level of anionic surfactant in the formulation. Nevertheless, there remains a need to boost this oily soil removal performance.

Moreover, alkylbenzene sulphonate surfactants are notoriously calcium-intolerant and the formulations require substantial levels of detergency builder (calcium builder). The builder, if water-soluble, also provides the necessary ionic strength and alkaline buffering to a pH at which the anionic surfactant can function most effectively. The most commonly used water-soluble detergency builder is sodium tripolyphosphate.

Sodium carbonate is also often present and provides some measure of calcium building as well as alkalinity.

The present invention, in its broadest content is therefore aimed at optimising oily soil removal using handwash detergent products containing high levels of anionic surfactant.

A subset of the invention is also aimed at solving the problem associated with the alkylbenzene sulphonates.

GB 1 570 128 (Procter & Gamble) discloses detergent compositions comprising from 4 to 40 wt% of a magnesium-insensitive surfactant (for example, alkyl ether sulphate, ethoxylated nonionic surfactant, amine oxide), from 13 to 40 wt% of sodium silicate, and from 5 to 50 wt% of a magnesium-selective detergency builder (for example, zeolite, sodium citrate, nitrilotriacetate, or calcite/carbonate).

JP 09 087 690A (Kao) discloses a high-bulk-density granular detergent composition for machine wash use, containing alpha-olefin sulphonate (5 to 40 wt%), plus ethoxylated nonionic surfactant (1 to 15 wt%), zeolite (10 to 40 wt%), and crystalline and amorphous sodium silicates (0.5 to 10 wt%).

WO 96 41857A and WO 96 05283A (Procter & Gamble) disclose laundry detergent compositions having a high surfactant to builder ratio, greater than 0.8: 1 and generally greater than 1: 1, but these products are preferably of low pH and do not contain especially high total surfactant levels or anionic surfactant levels.

The problem of increasing oily soil removal at high levels of anionic is solved by use of a non-calcium-binding or low-calcium-binding (non-calcium-building) buffer salt. The problem associated with the alkylbenzene sulphonates is solved by use of a calcium- tolerant non-soap anionic surfactant in combination with the buffer salt.

DEFINITION OF THE INVENTION The present invention provides a particulate laundry detergent composition suitable for the washing of textile fabrics by hand, which comprises:

(a) more than 40 wt% of an anionic surfactant system; (b) at least 30 wt% of inorganic salts comprising:- (bl) at least 20 wt% of a non-builder alkaline buffering agent; and (b2) optionally inorganic detergency builders and/or other inorganic salts; (c) optionally from 0 to 10 wt% of nonionic surfactant and/or fatty acid soap; and (d) optionally from 0 to 10 wt% of other detergent ingredients, all percentages being based on the weight of the total detergent composition.

DETAILED DESCRIPTION OF THE INVENTION The composition of the invention is based on a calcium-tolerant non-soap anionic surfactant system, present at a very high level, plus a high content of inorganic salts consisting predominantly or wholly of non-builder alkaline buffering agent.

Certain optional ingredients may also be present.

The anionic surfactant system (a) The composition of the invention contains a very high level-greater than 40 wt%- anionic surfactant. More than one anionic surfactant may be present. These may for example be selected from one or more of alkylbenzene sulphonates, primary and secondary alkyl sulphates, alkyl ether sulphates, alkyl olefin sulphonates, alkyl xylene

sulphonates, dialkyl sulphosuccinates, fatty acid ester sulphonates, alkyl amide sulphates, sorpholipids, alkyl glycoside sulphates and alkali metal (e. g. sodium) salts of saturated or unsaturated fatty acids.

However, the subset of the present invention which solves the problem associated with the alkylbenzene sulphonates requires at least 40% of calcium-tolerant non-soap anionic surfactant to be present. The total amount of anionic surfactant present is preferably at least 45 wt% and more preferably at least 50 wt%.

The preferred non-soap calcium tolerant anionic surfactant for use in the compositions of the present invention is alpha-olefin sulphonate.

Advantageously alkyl ether sulphate (another non-soap calcium tolerant material) may be present as a co-surfactant, in an amount less than that of the alpha-olefin sulphonate.

A preferred surfactant system comprises alpha-olefin sulphonate and alkyl ether sulphate in a weight ratio of from 2: 1 to 30: 1, preferably from 5: 1 to 15: 1.

Other calcium-tolerant anionic surfactants that may be used are alkyl ethoxy carboxylate surfactants (for example, Neodox (Trade Mark) ex Shell), and fatty acid ester sulphonates (for example, FAES MC-48 and ML-40 ex Stepan).

The inorganic salts (b) The compositions of the invention contain at least 30 wt%, preferably at least 40 wt% of inorganic salts (b). However, they differ from conventional formulations in that at least 20 wt% (based on the whole composition) consists of a non-detergency building (non- calcium-building, i. e. non-or low-calcium-ion-binding) alkaline buffering agent (bl).

The preferred alkaline buffering agent (bl) is sodium silicate which also provides magnesium building (effective magnesium ion binding). Sodium silicate is preferably present in an amount of from 20 to 55 wt%, more preferably from 25 to 55 wt%, still more preferably from 30 to 55 wt% and most preferably from 35 to 55 wt%.

If desired, the inorganic salts (b) may consist wholly of non-building material (bl) such as sodium silicate. However, it is also within the scope of the invention for inorganic detergency builders and/or other inorganic salts (b2) to be present. Suitable salts include sodium carbonate and sodium tripolyphosphate, each of which may suitably be present in an amount of from 5 to 40 wt%, preferably from 5 to 20 wt%.

According to a possible alternative embodiment of the invention, the alkaline buffering agent (bl) may be non-poisoned sodium carbonate. Sodium carbonate as a component of a calcite/carbonate builder system is a true calcium-binding builder. However, the carbonate on its own (i. e. without the calcite) is seldom a strong calcium binder because it is usually poisoned by another component in the formulation such as crystal growth inhibitors (e. g. low-medium MW polyacrylates), or even materials within the water or coming from the wash load itself. Sodium carbonate can also be deliberately poisoned so as to be low or non-calcium binding by inclusion in the formulation of, for example, a low level of sodium tripolyphosphate, so that it will not behave as a builder. The level of sodium tripolyphosphate must then be sufficient to poison the building of the carbonate.

In this alternative embodiment of the invention, sodium silicate may additionally be present as alkaline buffering agent, i. e. the alkaline buffering agent (bol) may comprise a combination of poisoned sodium carbonate and sodium silicate. Sodium tripolyphosphate or other poisoning builder is present as a builder or additional salt (b2).

In this alternative embodiment, the amount of poisoned sodium carbonate present is preferably from 20 to 55 wt%, more preferably from 25 to 50 wt%, most preferably from 20 to 35 wt%; the amount of sodium silicate is preferably from 0 to 35 wt%, more

preferably from 5 to 20 wt%; and from 0.1 to 20 wt% (e. g. 1 to 20 wt%), preferably from 0.5 to 10 wt% (e. g. 1 to 10 wt%) and more preferably from 0.5 wt% to 5 wt% (e. g. 1 to 5 wt%), of sodium tripolyphosphate is preferably present.

The optional nonionic surfactant and/or soap (c) If desired, nonionic surfactant and/or fatty acid soap may be included in order to control foam. The amount of these materials, in total, should not generally exceed 10 wt% and preferably will not exceed 5 wt%.

Preferred nonionic surfactants are the Cl0-C, 6 aliphatic alcohols having an average degree of ethoxylation of from 1 to 10, more preferably the C, 2-C, 5 alcohols having an average degree of ethoxylation of from 2 to 8.

The other ingredients (d) The compositions of the invention may also optionally contain up to 10 wt% of other beneficial ingredients.

Such ingredients are preferably selected from enzymes, antiredeposition agents, fluorescers, and perfumes, also bleaches, bleach precursors, bleach stabilisers, sequestrants, soil release agents (usually polymers) and other polymers.

According to a preferred embodiment of the invention, at least two enzymes selected from proteases, lipases, amylases and cellulases are present.

Preferred embodiments of the invention A preferred composition according to the invention comprises: (a) at least 45 wt% of a calcium-tolerant non-soap anionic surfactant system; (b) at least 40 wt% of inorganic salts comprising:- (bl) at least 30 wt% of a non-builder alkaline buffering agent; and (b2) optionally from 0 to 20 wt% of inorganic detergency builders and/or other inorganic salts; (c) optionally from 0 to 10 wt% of nonionic surfactant and/or fatty acid soap; and (d) optionally from 0 to 10 wt% of other detergent ingredients.

An especially preferred embodiment of the invention comprises: (a) at least 45 wt% of a calcium-tolerant anionic surfactant system comprising:- (al) from 45 to 55 wt% of alpha-olefin sulphonate; and (a2) optionally from 0 to 10 wt%, preferably from 2 to 10 wt% of alkyl ether sulphate; (bl) from 30 to 55 wt%, preferably from 35 to 55%, of sodium alkaline silicate; and (b2) from 0 to 20 wt% of inorganic detergency builders and/or other inorganic salts;

(c) optionally from 0 to 10 wt% of nonionic surfactant and/or fatty acid soap; and (d) from 0 to 10 wt% of other detergent ingredients selected from enzymes, antiredeposition agents, fluorescers, and perfumes.

An alternative embodiment of the invention, in which the non-building alkaline buffering agent is poisoned sodium carbonate, may be as follows: (a) at least 45 wt% of a calcium-tolerant anionic surfactant system comprising:- (al) from 45 to 55 wt% of alpha-olefin sulphonate; and (a2) optionally from 0 to 10 wt% of alkyl ether sulphate; (b) at least 40 wt% of inorganic salts comprising: (bl 1) from 20 to 55 wt%, preferably from 20 to 35 wt%, of sodium carbonate, (bl2) from 0 to 35 wt%, preferably from 5 to 20 wt%, of sodium alkaline silicate; and (b2) from 1 to 20 wt%, preferably from 1 to 10 wt%, of sodium tripolyphosphate; (c) optionally from 0 to 10 wt% of nonionic surfactant and/or fatty acid soap; and (d) from 0 to 10 wt% of other detergent ingredients selected from enzymes, antiredeposition agents, fluorescers, and perfumes.

In each of the preceding preferred embodiments, at least 0 to 100%, for example from 10% to 60% by weight of the surfactant (s) component (a) may be replaced by alkylbenzene sulphonate (where component (a) contains more than one component (al) and (a2), and are partially replaced, they are to be kept in the same weight ratios as before partial replacement.

Preparation of the compositions The compositions of the invention may be prepared by any suitable process.

The choice of processing route may be in part dictated by the stability or heat-sensitivity of the surfactants involved, and the form in which they are available.

For example, alpha-olefin sulphonate is robust, and is available in powder, paste and solution form.

Alkyl ether sulphate is more sensitive to heat, is susceptible to hydrolysis, and is available as concentrated (e. g. about 70% active matter) aqueous paste, and as more dilute (e. g. 28.5 wt%) solution.

In all cases, ingredients such as enzymes, bleach ingredients, sequestrants, polymers and perfumes which are traditionally added separately (e. g. enzymes postdosed as granules, perfumes sprayed on) may be added after the processing steps outlined below.

Suitable processes include: (1) drum drying of principal ingredients, optionally followed by granulation or postdosing of additional ingredients;

(2) non-tower granulation of all ingredients in a high-speed mixer/granulator, for example, a Fukae (Trade Mark) FS series mixer, preferably with at least one surfactant in paste form so that the water in the surfactant paste can act as a binder; (3) preparation, by spray-drying or by non-tower granulation as in (2), of a base powder composed of structured particles comprising inorganic salts and part of the surfactant, followed by admixture of additional surfactant in suitable granular form.

In all process routes, sodium alkaline silicate can be admixed in the form of solution, or as powder, or as sodium carbonate/sodium silicate granules, for example, Nabion (Trade Mark) 15 ex Rhodia.

When the anionic surfactant consists of or comprises an alkylbenzenesulphonate surfactant, it is preferably made by a non-tower route (NTR) granulation process (i. e. not by spray-drying), e. g. using a VRV-type mixer and an aluminosilicate layering agent is incorporated together with sodium carbonate, preferably in light powder form.

Typically, 60-100 parts by weight of powder from the mixer are made up to 100 parts with a minors granule produced by any convenient NTR process (e. g. containing perfume, speckles, enzymes (s), bleach and diluents).

The main powder prior to addition of the minors granule is typically formulated with the anionic surfactant, e. g. alkylbenzene sulphonate (up to 65% by weight, preferably up to 50% by weight), from 2-5% to 40% by weight of the light powder sodium carbonate, from 0% to 20% of diluents such as clay and or other salts, e. g. sodium tripolyphosphate and from 1 % to 40% of the aluminosilicate. The sodium carbonate is granulated with the anionic surfactant, preferably in acid form, and then layered with the aluminosilicate. Further diluents can also be added prior to layering.

EXAMPLES The invention is further illustrated by the following non-limiting Examples, in which parts and percentages are by weight unless otherwise stated.

EXAMPLE 1 The following formulation was prepared by drum drying alpha-olefin sulphonate paste (70 wt%), alkyl ether sulphate paste (70 wt%) and sodium alkaline silicate solution to form granules. Sodium carboxymethyl cellulose, fluorescer and enzymes were subsequently admixed. Ingredient wt% SodiumAOS 47 AES (C, 2-Cl5 3EO) 5 Sodium alkaline silicate 43 Sodium carboxymethyl cellulose 1.5 Florescer 0.2 (Tinopal (Trade Mark) CBS-X) Protease/lipasegranule 0.6 Cellulase 0.25 Precipitatedsilica 2

EXAMPLE 2 Alpha-olefin sulphonate (38 wt% solution), alkyl ether sulphate (28.5 wt% solution), fluorescer and sodium alkaline silicate (42 wt% solution) were mixed to form a slurry which was drum-dried. The resulting product was granulated in a Lödige Ploughshare mixer with additional AOS (38 wt% active), silica, sodium carboxymethyl cellulose, enzymes (Enzyme Ace protease/lipase granules and cellulase) and perfume. Raw materials and their suppliers were as in Example 1. The resulting formulation and some physical properties are shown below. wt% Drum drying SodiumAOS 45 AES (C, 2-C, 5 3EO) 5 Fluorescer (Tinopal CBS-X) 0. 2 Sodium alkaline silicate 42 l Total 92. 2 Ploughshare granulation SodiumAOS 1 Precipitated silica 0.3 Sodium carboxymethyl cellulose 1.5 Protease/lipase granule 0.6 Cellulase 0. 1 Perfume 0.5 Moisture 3.8 Total 7. 8 TOTAL PRODUCT 100. 0

Physical properties Bulk density 530 g/litre Dynamic flow rate 100 ml/sec Compressibility 19.3% v/v Dissolution (t90) 30 sec The t90 dissolution time is the time required for 90 wt% dissolution (as measured by a conductivity method).

Powder flow is expressed as dynamic flow rate which is measured by the following method.

The apparatus used consists of a cylindrical glass tube having an internal diameter of 35 mm and a length of 600 mm. The tube is securely clamped in a position such that its longitudinal axis is vertical. Its lower end is terminated by means of a smooth cone of polyvinyl chloride having an internal angle of 15° and a lower outlet orifice of diameter 22.5 mm. A first beam sensor is positioned 150 mm above the outlet, and a second beam sensor is positioned 250 mm above the first sensor.

To determine the dynamic flow rate of a powder sample, the outlet orifice is temporarily closed, for example, by covering with a piece of card, and powder is poured through a funnel into the top of the cylinder until the powder level is about 10 cm higher than the upper sensor; a spacer between the funnel and the tube ensures that filling is uniform.

The outlet is then opened and the time t (seconds) taken for the powder level to fall from the upper sensor to the lower sensor is measured electronically. The measurement is normally repeated two or three times and an average value taken. If V is the volume (ml) of the tube between the upper and lower sensors, the dynamic flow rate DFR (ml/s) is given by the following equation:

DFR = V ml/s t The averaging and calculation are carried out electronically and a direct read-out of the DFR value obtained.

A value of 80 ml/s or above is regarded as acceptable and a value of 100 ml/s or above is good.

EXAMPLE 3 Processing A 1.2m2 VRV machine was used, having three equal jacket sections. Dosing ports for both liquids and powders were situated just prior to the first hot section, with mid-jacket dosing ports available in the final two sections. Zeolite layering agent was added via this port in the final section. An electrically-powdered oil heater provided the heating to the first two jacket sections, with oil temperatures between 120°C and 190°C being used. Ambient process water at 15°C was used for cooling the jacket in the final section. Make-up air flow throughout the reactor was controlled between 10 and 50m3/hr by opening a bypass on the exhaust vapour extraction fan. All experiments were carried out with the motor at full speed, giving a tip speed of about 30m/s.

The majority of the solids were dosed via a screw feeder through the powder dosing port. Three screw feeders were calibrated, one to dose sodium carbonate, one to dose further diluent and the other to dose the zeolite for layering. A mono pump was calibrated to dose ambient temperature LAS anionic surfactant in acid form. This was dosed adjacent to the powder mixture, prior to the first hot section. Ingredientwt% SodiumLAS 42 Sodium Carbonate 35 SodiumTripolyphosphate Preciptated silica 1 Zeolite 4A 15 SokolanCP51 Lipolase 0. 5 Sodium Carboxymethyl Cellulose 0.24 Minors balance

COMPARATIVE EXAMPLE A A comparative formulation was prepared as follows: Ingredient wt% Sodium linear alkylbenzene sulphonate 26.7 Sodiumcarbonate 30 Sodiumtripolyphosphate 34 Nonionicsurfactant 2 C, 2-C, ; 7EO and 3EO Protease/lipase granule 0.6 Cellulase 0.25 Precipitatedsilica 4 Sodium carboxymethyl cellulose 1.5 Fluorescer (Tinopal CBS-X) 0. 2

DETERGENCY TESTING The detergencies of Example 2 (at 2.5 g/litre) and Comparative Example A (at 2.5 and 3.0 g/litre) were compared on new white de-sized polyester/cotton shirts and cotton vests, using a handwash and wear protocol.

The new shirts and vests were worn by male panellists on day 1 and were recalled for washing the following day. At the same time a second shirt and vest was issued to each panellist for wear on day 2 and washing on day 3. On day 3 a third shirt and vest would be issued and worn. The three shirt/vest combinations would each be washed using either Example 2 or one of the two concentrations of Comparative Example A.

The wash regime was as follows: the water hardness throughout was 24°FH (Ca: Mg 2: 1). First the garments were soaked for 30 minutes in a wash liquor (containing 2.5 or 3.0 g/litre concentration of test product, as stated) at a 5: 1 liquor to cloth ratio. The garments were all then removed and scrubbed, uniformly without overlapping on front and back using a plastic brush. The collar and armpit areas were brushed 3 times. The rinse was then conducted in a standardised fashion at a liquor to cloth ratio of 20: 1. The rinse step was then repeated two more times with excess water being wrung out each time.

At the end of this wash process the garments were air-dried in the shade, ironed and then reissued.

Redeposition test pieces of polyester, polyester-cotton, woven and knitted cotton were also washed, rinsed and dried along with the shirts and vests without any intermediate soiling steps.

Instrumental evaluations were made at the end of the 1 st, 3rd, 6th, 9th and 12th cycles.

The reduction in whiteness over twelve wash/wear cycles was monitored by means of the reflectance decrease at 460 nm.

The results were as follows: Table 1: The Reduction in R460* of polyester-cotton shirts (pocket area) during wash- wear

Cycle Example A 2.5g/l Example A Example 2 3.0 g/l 2.5 g/l New 84. 0 84. 0 84. 0 1 81.9 83.5 83.5 3 78. 9 80. 9 80. 6 6 76. 2 77. 2 79. 5 9 74. 8 74. 8 77. 7 12 74. 1 73. 3 77. 6 Table 2: the reduction in R460* of cotton vests during wash-wear Cycle Example A 2.5g/l Example A Example 2 3.0 g/l 2.5 g/l New 91. 0 91. 0 91.0 1 84. 0 88. 0 87. 6 3 83.3 85.1 85.1 6 79. 2 82. 3 84. 0 9 78. 8 80. 1 82. 3- 12 76. 7 77. 1 80. 3

It will be seen that the whiteness reduction of the articles washed using the composition of Example 2 was significantly and consistently lower than the reductions in whiteness of the articles washed using both levels of Comparative Example A.

The soil redeposition results on the four monitors were as shown in Tables 3 to 6.

Table 3: the reduction in R460* of knitted cotton redeposition monitors during wash- wear Cycle Example A 2.5g/l Example A Example 2 3.0 g/l 2. 5 g/l 3 81. 7 84. 7 86. 1 6 79. 0 80. 9 84. 4 9 75. 6 78. 2 83. 1 12 75. 6 77. 7 81. 6 Table 4: the reduction in R460* of woven cotton redeposition monitors during wash- wear Cycle Example A 2.5g/l Example A Example 2 3.0g/l 2. 5 g/l 3 83. 3 85. 8 86. 3 6 80. 6 82. 8 84. 5 9 78. 5 80. 5 83. 3 12 78. 1 80. 0 81. 8

Table 5: the reduction in R460* of Polyester-cotton redeposition monitors during wash- wear Cycle Example A 2.5g/l Example A Example 2 3.0g/l2. 5g/l 3 82. 1 83. 7 84. 3 6 79. 6 80. 7 82. 6 9 76. 7 78. 5 81. 2 12 77. 1 78. 9 80. 2 Table 6: the reduction in R460* of Polyester redeposition monitors during wash-wear Cycle Example A 2.5g/l Example A Example 2 3.0 g/l 2.5 g/l 3 84. 7 87. 0 87.5 6 82. 4 85. 0 86. 6 80. 8 83. 0 85. 2 12 83. 2 84. 7 Again Example 2 showed a significant benefit.

Ashing (deposition of inorganic salts on the articles) was also monitored after the twelve wash/wear cycles had been completed. A directional benefit for Example 2 was observed.

Validation of Sebum and Macrolex B test cloth.

Stain Preparation.

Initially tested on Indian woven cotton.

To make the dye and sebum, 0.08g of dye was added to 100ml of sebum. The sebum was at 60°C to allow for all of the components to be in the liquid state. This was then kept at 60°C and mixed for at least 30 minutes.

0.2ml of the sebum mixture was pipetted onto the centre of the fabric. This solidified instantly and so was placed in the oven for 1 hour to allow the liquid sebum to wick through the fabric.

The cloths were washed under the following conditions:- A liquid to cloth ratio (L/C) of 5: 1 was used at ambient temperature and 24°FH water (2: 1 Ca: Mg). The product was dosed at 2.5g/l. A 30 minute soak followed by two scrubs using the linear scrubbing rig, which carries a load weight of 1 kg.

This was then followed by three rinses at L/C ratio 10: 1 and 24°FH water.

They were line dried and read on the colour eye. The Delta R580* were measured using a Coloureye spectrophotometer.

The value attained, respectively for EXAMPLE 3 and COMPARATIVE EXAMPLE A were as follows:- <BR> Table 7 : The change in AR580* of dyed sebum-soiled Indian woven cotton Cycle Example A Example 3 X 1 16.9 18.9