CA1336386C

CA1336386C - Liquid detergent composition

Info

Publication number: CA1336386C
Application number: CA000594045A
Authority: CA
Inventors: David Alan Reed
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1988-03-21
Filing date: 1989-03-17
Publication date: 1995-07-25
Anticipated expiration: 2012-07-25
Also published as: EP0334566A2; ES2059728T3; AU611541B2; DE68917763T2; TR24196A; KR890014723A; PH25043A; AU3142389A; JP2521147B2; KR960000204B1; BR8901275A; IN168714B; MY104417A; DE68917763D1; EP0334566B1; JPH01304191A; EP0334566A3

Abstract

A pourable, homogenous, abrasive aqueous detergent composition, suitable for cleaning hard surfaces contains detergent active compound which is preferably a mixture of anionic and nonionic detergent active compounds, and the water soluble salt potassium sulphate in an amount sufficient to provide undissolved particles which act as an abrasive. The composition has an apparent viscosity which is sufficient to maintain the particles of salt in suspension during storage while ensuring that the composition remains pourable.

Description

1 33638~

LIQUID DETERGENT COMPOSITION

TECHNICAL FIELD
The invention relates to pourable, homogenous, aqueous liquid detergent compositions, especially compositions containing a water soluble particulate abrasive, which are suitable for the hand washing of dishes, crockery, cutlery and saucepans and also for the cleaning of other hard surfaces such as plastic laminate working surfaces, glass and ceramic tiles.

BACKGROUND
Liquid detergent compositions for cleaning hard surfaces are generally classified into two types. The first are aqueous suspensions conta~ng water-insoluble palpable abrasive particles: sometimes difficulty can be experienced when rinsing with water a hard surface that has been cleaned with such a composition, because insoluble particles of the abrasive can be difficult to remove completely from the surface. The second are liquid detergent compositions, usually containing soap, nonionics and alkyl benzene sulphonate, but with no palpable abrasive particles.

Liquid detergent compositions of the latter type, although free from the possible problem of scratching in use, nevertheless suffer from a number of drawbacks which can limit their consumer acceptability. They can, for example, have poor cle~n~ng performance on stubborn soil, especially in areas where the water is hard, due to the absence of an abrasive constituent. Also, they can suffer from poor homogeneity and can possess viscosity characteristics which are not ideal for use by the consumer. Moreover, the higher surfactant concentration necessary for in-use removal of grease and fatty soils can lead to excessive suds formation, which requires rinsing and wiping by the user. Although excessive suds production can be controlled to some extent by incorporation of a suds-regulating material such as solvents, hydrophobic silica and/or silicone or soap, this _ 2 l 336386 ln ltself can ralse problems of poor product stability and homogeneity, and problems associated wlth deposltion of insoluble residues on the items or surfaces being cleaned, ! leading to residual streaks and spots when dr~ed.

It has been proposed in US Patent No. 4 057 506 (Colgate Palmolive Company) to employ ln a heavy-duty liquid detergent composition a builder salt such as a water-soluble phosphate, silicate, borate, carbonate, bicarbonate or citrate in a manner such that the composltion is 10 substantially devoid of any builder salt in the form of solid particles, the composition being otherwise smooth and creamy. It is however an essential feature of the Colgate Palmolive's composition that any of the builder salt that is present in solid form is of colloidal-size particles having a particle size of <1~, usually <O.l,u.

It would appear that builder salt particles of this dimension, while possibly functioning as a builder, are too small to function as an abrasive. Such compositions are accordingly ineffective in cleaning heavily soiled hard surfaces as they lack scouring ability.
.
It has been proposed ln GB-A-1370377 to incorporate water-soluble salt in an essentially non-aqueous liquid composition, so that the salt remains undissolved and can act as an abrasive.

25 It has also been proposed in EP-A-0 193 375 (Unilever) to employ a water-soluble salt such as sodium bicarbonate in the form of undissolved particles having a mean particle diameter of from 10 to 500~m suspended in an aqueous detergent composition which is then suitable for cleaning hard surfaces. The sodium bicarbonate is intended to be of a suitable size to act as an abrasive, yet the composition is characterised by low soil redeposition and little or no propensity to causing streaking or spotting on surfaces washed therewith. This is apparently due to the ability of 3 1 33638b residusl partlcles of sodlum blcarbonate to dlssolve ln excess water used to rlnse the cleaned surface.

Experience has however shown that although sodium bicarbonate when employed as described in EP-A-O 193 375 performs as an excellent cleaner, the composition usually feels slimy to the touch and accordingly when used in the hand w~sh~ng of hard surfaces, such as dishes, cutlery and saucepans and the like without the use of gloves, it produces an unpleasant skin feel sensation sufficient to persuade the user to seek an alternative product.

Investigations have now shown that this undesirable property is due to the alkaline pH of the composition of 8.5 or higher, which is unavoidable when sodium bicarbonate is used in an amount sufficient to act as the sole water-soluble abrasive.

In our search for an alternative abrasive having water solubility and abrasive properties similar to sodium bicarbonate, but without the undesirable properties associated with such p~oducts, a large number of materials were examined.

Eventually it was discovered that potassium sulphate possessed the requisite abrasive properties and water solubility, and also it could be formulated into stable products having a neutral or slightly acid pH, which surprisingly possessed none of the unpleasant and unacceptable feel characteristics associated with similar product containing sodium bicarbonate.

DEFINITION OF THE INVENTION
Accordingly, the invention provides a pourable, homogeneous, abrasive, aqueous detergent composition, comprising, in addition to water:
i) detergent active;
ii) water soluble salt, at least part of which is potassium 4 ~ 33638~
sulphate, present ln both a dissolved and an undissolved ~tate, the undissolved part of the potasslum sulphate having a mean particle diameter of from 10 - 500 ~m;
the composition having a pH value not in excess of pH 8, and an apparent viscosity at 20C of at least 6500 Pas at a shear rate of 3 x 10- 5 sec~l and not more than 10 Pas at a shear rate of 21 sec~1.

Compositions of this invention possess suitability for hand dishwashing and/or cleaning other hard surfaces. Generally the compositions will be applicable in both ways and are thus dual purpose although not usually optimum for both applications. A composition can be formulated to be principally a hand dishwashing product, in which case it would have a fairly high level of detergent active with a low level of abrasive. Alternatively a composition can be formulated to be principally suitable for cleaning fixed hard surfaces and removing stubborn soils, in which case it would have a fairly high level of abrasive with a low level of detergent active.

DISCLOSURE OF THE INVENTION AND EMBODIMENTS THEREOF
Deterqent Active Compound The composition according to the invention will comprise detergent active. Suitably this is chosen from synthetic anionic detergent actives, and optionally also nonionic detergent actives.

Suitable synthetic anionic detergent active compounds are water-soluble salts of organic sulphuric reaction products having in the molecular structure an alkyl radical containing from 8 to 22 carbon atoms, and a radical chosen from sulphonic acid or sulphuric acid ester radicals and mixtures thereof. Examples of synthetic anionic detergents are sodium and potassium alkyl sulphates, especially those obtained by sulphating the higher alcohols produced by reducing the glycerides of tallow or coconut oil; sodium and ~ . . . .

potassium alkyl benzene sulphonates such as those in which the alkyl group contains from 9 to 15 carbon atoms, sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow and coconut oil;
sodium coconut oil fatty acid monoglyceride sulphates;
sodium and potassium salts of sulphuric acid esters of the reaction product of one mole of a higher fatty alcohol and from 1 to 6 moles of ethylene oxide; sodium and potassium salts of alkyl phenol ethylene oxide ether sulphate with from 1 to 8 units of ethylene oxide molecule and in which the alkyl radicals contain from 4 to 14 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralised with sodium hydroxide where, for example, the fatty acids are derived from coconut oil and mixtures thereof.

The preferred water-soluble synthetic anionic detergent active compounds are the ammonium and substituted ammonium (such as mono, di and triethanolamine), alkaline metal (such as sodium and potassium) and alkaline earth metal (such as calcium and magnesium) salts of higher alkyl benzene sulphonates, higher alkyl sulphonates, higher alkyl alpha-olefin sulphonates, higher alkyl sulphates, higher alkyl ether sulphates and mixtures thereof. Higher alkyl aromatic sulphonates may in particular be higher alkyl benzene sulphonates cont~n~ng from 6 or 8 to 20 or 22 carbon atoms in the alkyl group in a straight or branched chain.

Particularly preferred mixtures of anionic detergent actives comprise (i) sodium alkyl benzene sulphonate and sodium lauryl ether sulphate (2E0 to 8E0) and (ii) sodium secondary alkyl sulphonate with sodium lauryl ether sulphate.

The amount of synthetic anionic detergent active to be employed in the detergent composition of this invention will generally be from 1 to 40%, preferably from 2 to 25%, and -most preferably from 2 to 20% by weight.

.. . . .

Suitable nonionic detergent active compounds can be broadly described as compounds produced by the c~nden~tlon of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hyd,ophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily ad~usted to yield a water-soluble compound having the desired degree of ; balance between hydrophilic and hydrophobic elements.

Particular examples include the condensation product of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched chain configuration with ethylene oxide, such as a coconut oil ethylene oxide condensate having from 2 to 15 moles of ethylene oxide per mole of coconut alcohol: condensates of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with 5 to 25 moles of ethylene oxide per mole of alkylphenol; condensates of the reaction product of ethylenediamine and propylene oxide with ethylene oxide, the condensates containing from 40 to 80% of polyoxyethylene radicals by weight and having a molecular weight of from 5,000 to 11,000: tertiary amine oxides of structure R3N0, where one group R is an alkyl group of 8 to 18 carbon atoms and the others are each methyl, ethyl or hydroxyethyl groups, for instance dimethyldodecylamine oxide; tertiary phosphine oxides of structure R3P0, where one group R is an alkyl group of from 10 to 18 carbon atoms, and the others are each alkyl or hydroxyalkyl groups of l to 3 carbon atoms, for instance dimethyldodecylphosphine oxide; and dialkyl sulphoxides of structure R2S0 where the group R is an alkyl group of from 10 to 18 carbon atoms and ther other is methyl or ethyl, for instance methyltetradecyl sulphoxide; fatty acid alkylolamides; alkylene oxide condensates of fatty acid alkylolamides and alkyl mercaptans.

Mixtures of two or more of nonionic detergent actives can be employed in the detergent composition of the invention.

. ~ . .. . . . .

- 7 ~ 3363~6 The amount o~ nonionic detQrgent activs that can optionally b~ ~mployed in the detergent composition o~
the invention will g~nerally be ~rom 0.5 to 15%, preferably from 1 to 10%, and mo6t preferably from 1 to 8% by weight.

When both anionic and nonionic detergent actives are employed, the weiqht ratio of anionic detergent to nonionic detergent active can v~ry but i8 preferably ln the range of from 1:9 to 9:1, ideally from 1:4 to 4:1.

Preferably, the compositions contain an amount of both the anionic and the nonionic detergent active which is chosen so as to provide a ctructured liquid detergent composition, i.e. one which is 'self' thickened without necess~rily employing any thicken~ n~ agent per se.

According to an embodiment illustrating this aspect of the invention, the detergent compositions will comprise fro~ 2 to 16% by weight of a water-soluble, synthetic anionic sulphated or sulphonated detergent salt contA~tng an alkyl radical having from 8 to 22 carbon atoms in the molecule, and from 0.5 to 4% by weight of an alkyl~neQYylated nonionic detergent derived from the cond~nc~tion of an aliphatic alcohol having from 8 to 22 carbon atoms in the molecule with ethylene oxide, such that the conAen~te has from 2 to 15 moles of ethylene oxide per mole of aliphatic alcohol.
It is also possible optionally to include amphoteric , cationic or z~itterionic detergent actives in the compositions according to the invention.

Suitable amphoteric detergent-active compounds that optionally can be employed are derivatives of aliphatic secondary and tertiary amines contA~n~ng an alkyl group of 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilising y-o~, for .

lnat~nce sodlum 3-dodecylamlneoproplonate, sodlum 3-dodecylamlnopropane sulphonate and ~odium N-2-hydroxydodecyl-N-methyltaurate.

Sultable cationlc detergent-actlve compounds are guaternary ammonium salts haYing an allphatlc radical of from 8 to 18 carbon atoms, for lnstance cetyltrlmethyl ammonlum bromide.

Suitable zwltterionic detergent-active compounds that optionally can be employed are derivatives of aliphatic quaternary ammonium, sulphonium and phosphonium compounds having an aliphatic radical of from 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilising group, for instance 3-(N,N-dlmethyl-N-hexadecylammonium)propane-l-sulphonate betalne, 3-(dodecylmethyl sulphonium) propane-l- -sulphonate betaine and 3-(cetylmethylphosphonium) ethane sulphonate betaine.
Further examples of suitable detergent-active compounds are compounds commonly used as surface-active agents given in the well-known textbooks NSurface Active Agents", Volume I by Schwartz and Perry and "Surface Active Agents and Detergents", Volume II by Schwartz, Perry and Berch.

The total amount of detergent actlve compound to be employed in the detergent composition of the invention will generally be from 1 to 40%, preferably from 1.5 to 30%, more preferably 2 to 20 or 25% by weight.

The Water-soluble Salt The composition according to the invention will also - compri~e at least one water-soluble salt, namely potassium sulphate, which can function as an abrasive. This salt will be present in the composition in an amount in excess o its saturation solubility, and will accordingly be present in both a dissolved and an undissolved state. The composltlon wlll therefore comprlse a saturated aqueous solution of potasslum sulphate together wlth from 0.5 to 60% more preferred from 1-50% by welght of the composltlon at 20C ln the form of a solld phase - 5 comprising particles of the salt havlng a mean particle diameter of from 10 to 500~m preferably from 20 to 300~m, to provide the necessary abraslve properties.

The water-soluble salt potassium sulphate is anh~dLous and does not change into any hydrated species when present as a crystalline solid in water at a temperature of from 10C to 40C in an amount in excess of that required to form a saturated solution. The saturation solubility of the salt in water at 40C is less than twice that at 10C. These properties help to ensure that the characteristics of the product, in particular the size, shape and amount of crystalline abrasive particles, do not change significantly over the normal temperature range of use. Uniformity of performance is accordingly ensured. These properties of potassium sulphate also help to ensure that when the composition is self structured - that is to say the structure which provides the desired viscosity characteristics is derived from an appropriate choice of anionic detergent active(s) or anionic and nonionic detergent actives - it will remain stable without substantial change in viscosity.

The water-soluble salt potassium sulphate has a Mohs hardness of about 3, which provides useful abrasive properties. It has a saturation solubility in water which at 10C does not exceed 15% by weight, so allowing the presence of undissolved particles at reasonable total inclusion levels.

The salt also has a solubility in water of more than 5 g/l at 10C, which ensures that any surplus salt can readily be rinsed from a hard surface after cleaning with the composition. In this way, the surface can be free from .

' - 10 residual spotCi or strea~s.

The total amount of the potassium sulphate present in the detergent composltion, both in dlssolved and undissolved form, should preferably be from 2 to 65~, more preferably 5 from 4 to 55%, and ideally 7 to 50% by welght. Dependent on the specific abrasive level required, from 0.5 to 60%, more preferably from 1-50% by weight of the water-soluble salt should be present in the composition, at normal storage or use temperatures of from 10 to 40C, in a solid, particulate form, having an average particulate size, and other characteristics, as herein defined.

In addition to potassium sulphate, the composition according to the invention can also optionally comprise other water-soluble salts such as sodium bicarbonate, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium tripolyphosphate pentahydrate, sodium tetraborate decahydrate and sodium citrate, provided that the pH value of the composition does not exceed pH 8. With this proviso, it is furthermore also posssible to use other water-soluble inorganic salts or organic salts of lithium, magnesium, sodium, potassium and calcium, which salts can possibly function as builders and abrasives. Specific examples are sodium oxalate, sodium succinate, sodium adipate and sodium glutarate. Mixtures of such salts can be employed. The presence of electrolytes which are capable of slightly reducing the solubility of potassium sulphate in water is preferred. Especially suitable in this respect is the incorporation of alkali metal chlorides, preferably sodium chloride, at a level of from 0.5 to 5~, or higher, up to 10~, of the composition. This effects a small reduction of the solubility of potassium sulphate in water, thereby reducing the required amount of potassium sulphate for obt~ining an adeguate level of undissolved particles, but at the same time does not reduce the solubility of potassium sulphate to below a level of 5 g/litre, thereby ensuring that any surplus salt can readily be removed from a hard .. . _ , . . . .

11 1 3363~6 surface after cleAni n~.

- The presence of electrolytes, especlally sodium chloride, is also advantageous in that the freeze-thaw stability of the product is im~o~ed.

Especially advantageous ls the incorporation of another electrolyte additionally to the alkall metal chlorides, this additional electrolyte is preferably an alkali metal citrate such as sodium citrate, which provides the additional benefit of pH regulation.

It is preferred that the total amount of water-soluble salt, including potassium sulphate, is at least 9% by weight of the composition. It may lie in the range from 9 to 50% by weight.

Water The composition according to the invention will also comprise water which will generally form from 30 to 89.5~, preferably from 40 to 80%, and ideally 45 to 70% by weight of the composition.

Optional Ingredients The composition according to the invention can contain other ingredients which aid in their cleaning performance, provided that due to the presence of these other ingredients the pH value of the composition does not exceed pH 8. For example, the composition can contain detergent builders such as nitrilotriacetates, polycarboxylates, citrates, dicarboxylic acids, water-soluble phosphates especially polyphosphates, mixtures of ortho- and pyrophosphate and mixtures thereof. Such builders can additionally function as abrasives if present in an amount in excess of their solubility in the overall composition as explained herein.
In general, the builder, when employed, preferably will form from 0.1 to 25~ by weight of the composition.

I
_ 12 l 3363~6 Metal lon egueotrants such a-thylenediauinetetraacetate~, amlno-polyphosphonates ~ S.) and phosph_te~ and a wlde varlety of other S poly-functlonal organlc acld~ and ~alt~, can also optlonally be employed.

A further optlonal i..y-ediQnt for compo6itlon~ according to the lnventlon 18 a suds regulating material, whlch can be employed ln composltlons accordlng to the lnventlon whlch have a tenA~cy to produce excessive suds in use. One example of a suds regulating material is 60ap. Soaps are salts of fatty acids and include alkali metal soaps such as the sodium, potassium, ammonlum and alkanol ammonlum salt~ of higher fatty aclds contalnlng from about 8 to about 24 carbon atoms, and preferably from about lO to about 20 carbon atoms.
Particularly useful are the ~odium and potasslum and mono-, di- and triethanolamine salts of the mlxtures of fatty aclds derived from coconut oil and ground nut oil.
When employed, the amount of soap can from at least 0.005%, preferably 0.5% to 2% by welght of the composition. A further example of a suds regulating material ls an organic solvent, hydrophobic sllica and a silicone oil or hydrocarbon~.

The compositions according to the invention may optionally contaln structurlng agents to ald in provlding appropriate rheological properties to maintain the llnA ~olved salt or salts uniformly distributed in the composition and in ~nhA~cing their distribution and adherence of the composition to the hard surface to be cleaned. Preferred structuring agents include polysaccharides, such as sodium carboxymethyl cellulose and other chemically modified cellulose materials, xanthan gum and other non-flocculating structuring agents such as 8iopolymer PS87 referred to in US Patent No. 4 329 448. Certain polymers such as a polymer of acrylic acid cross-linked with a poly functional agent, C A 1 ~ 3 6 3 86 for example *CARBOPOL, can also be used as structuring agents. The amount of such structuring agents, when employed, to be used in compositions according to the invention can be as little as 0.001%, preferably at least 0.01% by weight of the composition.

The compositions according to the invention can also comprise at least partially esterified resin such as an at least partially esterified adduct of rosin and an unsaturated dicarboxylic acid or anhydride, or an at least partially esterified derivatives of co-polymerisation products of mono-unsaturated aliphatic, cycloaliphatic or aromatic monomers having no carboxy groups and unsaturated dicarboxylic acids or anhydrides thereof.

Typical examples of suitable copolymers of the latter type are copolymers of ethylene, styrene, and vinylmethylether with maleic acid, fumaric acid, itaconic15 acid, citraconic acid and the like and the anhydrides thereof. Preferred are the styrene/maleic anydride copolymers.

In general, the compositions of the invention can optionally comprise from 0.005 to 20%, usually from 0.1 to 15% and preferably from 0.5 to 10% by 20 weight of the at least partially esterified resin.

Compositions according to the invention can also contain, in addition to the ingredients already mentioned, various other optional ingredients such as pH
regulants, perfumes, colourants, optical brighteners, soil suspending agents, 25 detersive enzymes, compatible bleaching agents, gel-control agents, freeze-thaw stabilisers, bactericides, preservatives, detergent hydrotropes, opacifiersand solvents.

The compositions according to the invention will not contain more than 10%, 30 preferably not more than 5% by C~ 1 336386 weight of a water-insoluble abrasive, such as felspar and quartz, in view of the tendency of such abrasives to leave a deposit on hard surfaces after cleaning, even when rinsed with water.

Ideally, compositions according to the invention are substantially free from water-insoluble abrasives.

Generally, the water and optional ingredients comprising other detergent adjuncts will form the balance of the composition, after accounting for the detergent active compound and the water-soluble salt ingredients.
Accordingly, the water and optional ingredients can form from 89.5 to 25% by weight of the composition.

e~
It is an important feature of the invention that the compositions area formulated so as to have a pH value which does not exceed 8. Preferably the composition have a pH value of from 5 to 8, ideally about pH 6-7, although pH values of as low as 3 are acceptable.
Suspending Properties It is an important feature of the invention that the composition will be capableof suspending the undissolved particles of salt abrasive, so that the consumer does not need to agitate the composition, for example by shaking it, in order to re-suspend and re-distribute sedimented particles prior to use. For this purpose, the composition should preferably have an apparent viscosity at 20C of at least 6500 Pas at a shear rate of 3 x 10 sec. to ensure that the particles of salt abrasive do not sediment on standing at 20C by more than 1 cm in one month. Ideally, the apparent viscosity at 20C is at least 25,000 Pas at a shear rate of 3 x 10 5 sec.

C~ 1 336386 This viscosity value can be determined by application of Stokes Law, with the assumption that the particles of salt abrasive are spherical, and that the above sedimentation rate applies.

While it is necessary to ensure that the composition according to the invention has an apparent viscosity which is high enough to prevent any substantial settlement of the undissolved particles of salt abrasive during storage, it should remain fluid, so that it can readily be poured from a bottle or other container when required for use. For this purpose, the composition should have an apparent viscosity at 20C, measured using a rotational viscometer which does not exceed 10 Pas at a shear rate of 21 sec. 1. Preferably, the apparent viscosity at 20C is no greater than 5 Pas at a shear rate of 21 sec Suitable rheological conditions to suit these criteria can be provided by judicial choice of anionic and nonionic detergent to provide a structured liquidhaving the requisite suspending properties, and/or by use of an appropriate amount of an alternative structuring agent such as is described herein.
A preferred method for adapting the viscosity of the composition is by the inclusion of water-soluble polymers into the system, such as for instance described in our co-pending Canadian application 572,952.

Process for Preparation of ComPositions Since the compositions according to the invention are in liquid form, they can be prepared simply by blending the essential and optional ingredients in water.

Packaging and Use of the Compositions The compositions according to the invention are pourable liquids that are preferably contained in a closable

Claims

1. A pourable, homogeneous, abrasive, aqueous detergent composition comprising, in addition to water:

i) 1.5 to 40% by weight of detergent active;

ii) 9 to 65% by weight of water soluble salt, at least part of which is potassium sulphate in an amount which is

2 to 65% by weight of the composition and present in both a dissolved and an undissolved state, the undissolved part of the potassium sulphate having a mean particle diameter of from 10 - 500 µm;

the composition having a pH of less than 8, and having an apparent viscosity at 20°C of at least 6500 Pas at a shear rate of 3 x 10-5 sec-1, and not more than 10 Pas at a shear rate of 21 sec-1.

2. A composition according to claim 1 wherein the amount of detergent active is 1.5 to 30% by weight of the composition and the amount of water soluble salt is 9 to 50% by weight of the composition.

3 . A composition according to claim 1 wherein the water soluble salt comprises at least one electrolyte capable of lowering the solubility of the potassium sulphate.

4 . A composition according to claim 3 wherein the electrolyte comprises alkali metal chloride in an amount from 0.5 to 10% by weight of the composition.

5 . A composition according to claim 1 wherein anionic detergent active forms from 1 to 25% by weight of the composition.

6 . A composition according to claim 5 wherein the detergent active comprises from 2 to 20% by weight of the composition of a water soluble synthetic anionic sulphated or sulphonated detergent salt containing an alkyl radical having from 8 to 22 carbon atoms in the molecule.

7 . A composition according to claim 5 wherein nonionic detergent active forms from 0.5 to 15% by weight of the composition.

8 . A composition according to claim 7 wherein the weight ratio of anionic to nonionic detergent active is from 1:9 to

9:1.

9 . A composition according to claim 1 wherein the water soluble salt additionally comprises sodium citrate.

10. A composition according to claim 1 wherein the undissolved potassium sulphate has a mean particle diameter of from 20 to 300µm.

11. A composition according to claim 1 wherein water comprises from 30 to 89.5% by weight of the composition.

12. A composition according to claim 11 wherein water comprises from 40 to 80% by weight of the composition.

13. A composition according to claim 1 which has an apparent viscosity at 20°C of at least 25,000 Pas at a shear rate of 3 x 10-5 sec-1.

14. A composition according to claim 1 which has an apparent viscosity at 20°C of not more than 5 Pas at a shear rate of 21 sec-1.

15. A pourable, homogenous, abrasive, aqueous detergent composition suitable for cleaning hard surfaces and for hand dishwashing comprising:

i) from 2 to 25% by weight of a water soluble synthetic anionic sulphated or sulphonated detergent salt containing an alkyl radical having from 8 to 22 carbon atoms in the molecule;

ii) from 9 to 65% by weight of water soluble salt, at least part of which is potassium sulphate in an amount which is 2 to 65% by weight of the composition and present in both a dissolved and an undissolved state, the undissolved part of the potassium sulphate having a mean particle diameter of from 10 - 500µm and constituting from 0.5 to 60% by weight of the composition;

iii) from 30 to 80% by weight of water;

the composition having a pH value not in excess of pH 8, and having an apparent viscosity at 20°C of at least 25,000 Pas at a shear rate of 3 x 10-5 sec-1, and not more than 5 Pas at a shear rate of 21 sec-1.