GB2237285A - Liquid soap composition - Google Patents

Abstract

Method of making a soap containing non-aqueous liquid detergent composition by forming a predispersion of the soap and mixing the pre-dispersion with the remaining ingredients.

Description

LIQUID DETERGENT COMPOSITION AND METHOD FOR ITS PREPARATION BACKGROUND This invention relates to a non-aqueous liquid detergent composition, especially but not exclusively, to such compositions suitable for fabric washing. The invention also provides a process for preparing such a composition.

Non-aqueous liquid detergent compositions have been described in the art. They may be preferred to aqueous liquid compositions in that they are more concentrated and provide the possibility of including water-sensitive ingredients, such as bleaches, bleach precursors and enzymes. Liquid detergent compositions in general are preferred over powders for their more rapid dispersion and dissolution in the wash liquor.

Non-aqueous liquid detergent compositions generally comprise a liquid continuous phase which is often made up of a liquid surfactant material, preferably a nonionic surfactant material, optionally together with other liquid phase ingredients. Suspended in the liquid phase are particulate solid ingredients such as detergency builders and bleaches.

A useful ingredient in many detergent compositions is a soap, that is the salt of a natural or synthetic fatty acid, the cation generally being an alkali metal. Soaps may provide a detergency benefit, they exert a controlling effect on foam generated in aqueous wash liquors which can be especially important when automatic washing machines are used, and in the case of fabric washing compositions, they may provide a fabric softening effect.

However, the incorporation of soap in non-aqueous liquid detergents has been found to be difficult.

Problems which often arise are the generation of a physically unstable system in which they may develop undesirable rheological properties, particularly to the extent of being very thick, or even setting to a solid phase.

Non-aqueous liquids containing soap and a solvent for the soap, such as ethanol are described in FR 2069073 (Unilever) and our copending application GB 8909801.6 filed 28 April 1989. It may be desirable to exclude the presence of these solvents for a number of reasons. For example, such solvents may induce physical or chemical instability, they represent a relatively non-useful ingredient so far as the cleaning process is concerned, they may present a fire hazard or they may have an undesirable odour.

We have now found that the problems of incorporating soap can be alleviated or totally overcome if the soap is pretreated in a specified manner, before being incorporated in the product.

DESCRIPTION OF THE INVENTION Thus according to the invention there is provided a method of producing a stable, pourable non-aqueous liquid cleaning composition comprising a liquid phase and a dispersed particulate solid phase and containing up to 10t by weight soap, the method comprising the steps of: i) contacting the soap with at least one liquid phase ingredient, heating to a temperature above 1000C to form a pourable liquid pre-dispersion containing from 3% to 20% by weight soap; and thereafter ii) mixing the soap pre-dispersion with the particulate solid phase and optionally further liquid phase ingredients.

The method according to the invention is suitable for preparing products with up to 10% soap, this level being sufficient for the desired detergency, foam control and fabric softening benefits.

It is important that the pre-dispersion is heated to above 1000C, such as from 1100C to 1500C. Successful results can be obtained by heating to 1300C. Heating to a temperature below 1000C, such as to 900C leads to a predispersion with too high a viscosity, unsuitable for mixing with other ingredients of the product. It is possible for the soap and the liquid phase to be heated together or alternatively soap at ambient temperature may be added to the already-heated liquid phase.

The predispersion preferably contains from 10% to 15% soap. Generally, no further soap will be added with the other ingredients. The predispersion will contain some or all of the liquid phase ingredients, but preferably a part of the liquid phase is used to disperse the remaining ingredients prior to mixing with the soap pre-dispersion.

The pre-dispersion is preferably cooled to a temperature below 80"C such as below 400C, most preferably below 300C before being mixed with other ingredients.

Where the other ingredients are at an elevated temperature, such as because they have just been subjected to milling or some other heat generating process, it is advantageous that the mixing take place at a similar temperature, eg. with tioac.

If the dispersion of the remaining ingredients involves particle size reduction, for example by milling, we prefer to add the soap pre-dispersion after such milling has taken place.

Also within the scope of the invention is a stable and pourable non-aqueous liquid cleaning composition comprising a liquid phase and a dispersed solid phase, the composition containing from 0.58 to 108 by weight of soap and being substantially free of solvents for the soap.

As used herein the term "stable and pourable means that the viscosity of the composition when measured at 21 before and after closed storage for 1 month at 370C shown no significant increase, ie. allowing for experimental error there is either no increase in viscosity or there is a decrease in viscosity over this period. Furthermore the viscosity of the composition 21s -1 should be less than 3000mPa.s at 21s , preferably less than 2000mPa.s. Preferably the composition has this negative viscosity gradient throughout its life, especially when freshly prepared. A positive viscosity gradient is an indication of progressive setting in the product. A viscosity above 3000 mPa.s. is an indication of an unacceptable product, outside the scope of a stable and pourable product.Such unacceptable products will generally have the appearance of being solid or immobile liquids.

The term "solvent" in this context is any normally liquid ingredient which is capable of dissolving 1% by weight of particulate soap when'left to stand at 200C for 1 week without agitation.

By "substantially free of solvents for the soap" is meant that the composition contains less than 5%, such as less than 1% by weight of a liquid solvent for the soap, especially solvents selected from ethanol, hexane, heptane, benzene, xylene, toluene, tetrahydrofuran, dimethylsuphoxide, di-Cl-C4 alkylene glycols and polyethylene glycols of molecular weight up to 1000.

While not wishing to be bound by any theory, it is thought that the process of forming a pre-dispersion of the soap in the liquid phase ingredients, and heating this pre-dispersion to a temperature above 1000C, causes a phase change in the soap which is retained on cooling and which, contrary to the soap phase prior to this process, does not encourage agglomeration and subsequent setting of the product.

SOAPS Soaps useful in the present invention are the salts of alkali metals, especially sodium or potassium, and fatty acids, for example those containing from 12 to 18 carbon atoms. Typical such acids are oleic and ricinoleic acids and fatty acids derived from caster oil, rapeseed oil, groundnut oil, coconut oil, palmkernal oil or mixtures thereof. We have found it preferable to use soaps containing relatively high proportions of longer fatty chains. Thus we prefer to use soaps where the proportion of chain lengths greater than C17 to chain lengths less than C17 is higher than 1:1. We also prefer to use soaps of saturated acids. The soap is thought to be present in the product in the solid phase.

PRODUCT FORM All compositions according to the present invention are liquid cleaning products. They may be formulated in a very wide range of specific forms, according to the intended use. They may be formulated as cleaners for hard surfaces (with or without abrasive) or as agents for warewashing (cleaning of dishes, cutlery etc) either by hand or mechanical means, as well as in the form of specialised cleaning products, such as for surgical apparatus or artificial dentures. They may also be formulated as agents for washing and/or conditioning of fabrics.

In the case of hard-surface cleaning, the compositions may be formulated as main cleaning agents, or pre-treatment products to be sprayed or wiped on prior to removal, e.g. by wiping off or as part of a main cleaning operation.

In the case of warewashing, the compositions may also be the main cleaning agent or a pre-treatment product, e.g applied by spray or used for soaking utensils in an aqueous solution and/or suspension thereof.

Those products which are formulated for the cleaning and/or conditioning of fabrics constitute an especially preferred form of the present invention because in that role, there is a very great need to be able to incorporate substantial amounts of various kinds of solids. These compositions may for example, be of the kind used for pre-treatment of fabrics (e.g. for spot stain removal) with the composition neat or diluted, before they are rinsed and/or subjected to a main wash. The compositions may also be formulated as main wash products, being dissolved and/or dispersed in the water with which the fabrics are contacted. In that case, the composition may be the sole cleaning agent or an adjunct to another wash product.Within the context of the present invention, the term 'cleaning composition' also embraces compositions of the kind used as fabric conditioners (including fabric softeners) which are only added in the rinse water (sometimes referred to as 'rinse conditioners').

Thus, the compositions will contain at least one agent which promotes the cleaning and/or conditioning of the article(s) in question, selected according to the intended application. Usually, this agent will be selected from non-soap surfactants, enzymes, bleaches, microbiocides, (for fabrics) fabric softening agents and (in the case of hard surface cleaning) abrasives. Of course in many cases, more than one of these agents will be present, as well as other ingredients commonly used in the relevant product form.

NON-SOAP SURFACTANTS Where such surfactants are solids, they will usually be dissolved or dispersed in the liquid phase. Where they are liquids, they will usually constitute all or part of the liquid phase. However, in some cases the surfactants may undergo a phase change in the composition.

In general, surfactants for use in the compositions of the invention may be chosen from any of the classes, sub-classes and specific materials described in 'Surface Active Agents' Vol. I, by Schwartz & Perry, Interscience 1949 and 'Surface Active Agents' Vol. II by Schwartz, Perry & Berch (Interscience 1958), in the current edition of "McCutcheon's Emulsifiers & Detergents" published by the McCutcheon division of Manufacturing Confectioners Company or in 'Tensid-Taschenbuch', H. Stache, 2nd Edn., Carl Hanser Verlag, Mtnchen & Wien, 1981.

In respect of all surfactant materials, but also with reference to all ingredients described herein as examples of components in compositions according to the present invention, unless the context requires otherwise, the term "alkyl" refers to a straight or branched alkyl moiety having from 1 to 30 carbon atoms, whereas lower alkyl refers to a straight or branched alkyl moiety of from 1 to 4 carbon atoms. These definitions apply to alkyl species however incorporated (e.g. as part of an aralkyl species).

Alkenyl (olefin) and alkynyl (acetylene) species are to be interpreted likewise (i.e. in terms of configuration and number of carbon atoms) as are equivalent alkylene, alkenylene and alkynylene linkages. For the avoidance of doubt, any reference to lower alkyl or C 1-4 alkyl (unless the context so forbids) is to be taken specifically as a recitation of each species wherein the alkyl group is (independent of any other alkyl group which may be present in the same molecule) methyl, ethyl, iso-propyl, n-propyl, n-butyl, iso-butyl and t-butyl, and lower (or C alkylene is to be construed likewise.

NON-IONIC SURFACTANTS Nonionic detergent surfactants are well-known in the art. They normally consist of a water-solubilizing polyalkoxylene or a mono- or di-alkanolamide group in chemical combination with an organic hydrophobic group derived, for example, from alkylphenols in which the alkyl group contains from about 6 to about 12 carbon atoms, dialkylphenols in which each alkyl group contains from 6 to 12 carbon atoms, primary, secondary or tertiary aliphatic alcohols (or alkyl-capped derivatives thereof), preferably having from 8 to 20 carbon atoms, monocarboxylic acids having from 10 to about 24 carbon atoms in the alkyl group and polyoxypropylenes. Also common are fatty acid mono- and dialkanolamides in which the alkyl group of the fatty acid radical contains from 10 to about 20 carbon atoms and the alkyloyl group having from 1 to 3 carbon atoms.In any of the mono- and dialkanolamide derivatives, optionally, there may be a polyoxyalkylene moiety joining the latter groups and the hydrophobic part of the molecule. In all polyalkoxylene containing surfactants, the polyalkoxylene moiety preferably consists of from 2 to 20 groups of ethylene oxide or of ethylene oxide and propylene oxide groups.

Amongst the latter class, particularly preferred are those described in the applicants' published European specification EP-A-225,654, especially for use as all or part of the liquid phase. Also preferred are those ethoxylated nonionics which are the condensation products of fatty alcohols with from 9 to 15 carbon atoms condensed with from 3 to 11 moles of ethylene oxide. Examples of these are the condensation products of C 11-13 alcohols with (say) 3 or 7 moles of ethylene oxide. These may be used as the sole nonionic surfactants or in combination with those of the described in the last-mentioned European specification, especially as all or part of the liquid phase.

Another class of suitable nonionics comprise the alkyl polysaccharides (polyglycosides/oligosaccharides) such as described in any of specifications US 3,640,998; US 3,346,558; US 4,223,129; EP-A-92,355; EP-A-99,183; EP 70,074, '75, '76, '77; EP 75,994, '95, '96.

Mixtures of different nonionic detergent surfactants may also be used. Mixtures of nonionic detergent surfactants with other detergent surfactants such as anionic, cationic or ampholytic detergent surfactants and soaps may also be used.

SYNTHETIC ANIONIC SURFACTANTS Examples of suitable anionic detergent surfactants are alkali metal, ammonium or alkylolamine salts of alkylbenzene sulphonates having from 10 to 18 carbon atoms in the alkyl group, alkyl and alkylether sulphates having from 10 to 24 carbon atoms in the alkyl group, the alkylether sulphates having from 1 to 5 ethylene oxide groups, and olefin sulphonates prepared by sulphonation of C10-C24 alpha-olefins and subsequent neutralization and hydrolysis of the sulphonation reaction product.

OTHER NON-SOAP SURFACTANTS It is also possible to utilise cationic, zwitterionic and amphoteric surfactants such as referred to in the general surfactant texts referred to hereinbefore.

Examples of cationic detergent surfactants are aliphatic or aromatic alkyl-di(alkyl) ammonium halides. Ampholytic detergent surfactants are e.g. the sulphobetaines.

Combinations of surfactants from within the same, or from different classes may be employed to advantage for optimising structuring and/or cleaning performance.

The compositions will be substantially free from agents which are detrimental to the article(s) to be treated. For example, they will be substantially free from pigments or dyes, although of course they may contain small amounts of those dyes (colourants) of the kind often used to impart a pleasing colour to liquid cleaning compositions, as well as fluorescers, bluing agents and the like.

All ingredients before incorporation will either be liquid, in which case, in the composition they will constitute all or part of the liquid phase, or they will be solids, in which case, in the composition they will either be dispersed as deflocculated particles in the liquid phase or they will be dissolved therein. Thus as used herein, the term "solids" is to be construed as referring to materials in the solid phase which are added to the composition and are dispersed therein in solid form, those solids which dissolve in the liquid phase and those in the liquid phase which solidify (undergo a phase change) in the composition, wherein they are then dispersed. To control the dispersion of the solid phase particulate ingredients in the liquid phase, it is usual to include a deflocculant, especially of the type as described herein.

THE LIQUID PHASE It is necessary that the liquid phase should be such as to enable the particulate solid ingredients to be stably suspended therein. The suitability of a given liquid for use as the liquid phase in compositions according to the invention will depend upon the nature of other ingredients of the composition. Thus, some liquids are alone, unlikely to be suitable to perform the function of liquid phase for any combination of ingredients.

However, they will be able to be incorporated if used with another liquid which does have the required properties, the only requirement being that where the liquid phase comprises two or more liquid ingredients, they are miscible when in the total composition or one can be dispersible in the other, in the form of fine droplets.

As a general rule, the most suitable liquids to choose as the liquid phase are those organic materials having polar molecules. In particular, those comprising a relatively lipophilic part and a relatively hydrophilic part, especially a hydrophilic part rich in electron lone pairs, tend to be well suited. This is completely in accordance with the observation that liquid surfactants, especially polyalkoxylated nonionics, are one preferred class of material for the liquid phase.

LEVEL OF LIQUID PHASE Preferably, the compositions of the invention contain the liquid phase (whether or not comprising liquid surfactant) in an amount of at least 10% by weight of the total composition. The amount of the liquid phase present in the composition may be as high as about 90%, but in most cases the practical amount will lie between 20 and 70% and preferably between 20 and 50% by weight of the composition.

SOLIDS CONTENT In general, the solids content of the product may be within a very wide range, for example from 1-90%, usually from 10-80% and preferably from 15-70%, especially 15-50% by weight of the final composition. The solid phase should be in particulate form and have an average particle size of less than 300 microns, preferably less than 200 microns, more preferably less than 100 microns, especially less than 10 microns. The particle size may even be of sub-micron size. The proper particle size can be obtained by using materials of the appropriate size or by milling the total product in a suitable milling apparatus. In order to control aggregation of the solid phase leading to unredispersible settling or setting of the composition, it is preferred to include a deflocculant therein.

THE DEFLOCCULANT In principle, any material may be used as a deflocculant provided it fulfils the deflocculation test described in European Patent Specification EP-A-266199 (Unilever). The capability of a substance to act as a deflocculant will partly depend on the solids/liquid phase combination. However, especially preferred are acids.

Some typical examples of deflocculants include the alkanoic acids such as acetic, propionic and stearic and their halogenated counterparts such as trichloracetic and trifluoracetic as well as the alkyl (e.g. methane) sulphonic acids and aralkyl (e.g. paratoluene) sulphonic acids.

Examples of suitable inorganic mineral acids and their salts are hydrochloric, carbonic, sulphurous, sulphuric and phosphoric acids; potassium monohydrogen sulphate, sodium monohydrogen sulphate, potassium monohydrogen phosphate, potassium dihydrogen phosphate, sodium monohydrogen phosphate, potassium dihydrogen pyrophosphate, tetrasodium monohydrogen triphosphate.

Other organic acids may also be used as deflocculants, for example formic, lactic, citric, amino acetic, benzoic, salicylic, phthalic, nicotinic, ascorbic, ethylenediamine tetraacetic, and aminophosphonic acids.

Peracids such as percarboxylic and persulphonic acids may also be used.

The class of acid deflocculants further extends to the Lewis acids, including the anhydrides of inorganic and organic acids. Examples of these are acetic anhydride, maleic anhydride, phthalic anhydride and succinic anhydride, sulphur-trioxide, diphosphorous pentoxide, boron trifluoride, antimony pentachloride.

Suitable deflocculants are also found amongst salts.

Already mentioned are salts with a hydrogen content such that they case release a proton, for example the alkali metal hydrogen phosphates and hydrogen sulphates.

However, other organic and inorganic salts may be used successfully, according to the nature of the solids/liquid phase combination. It could be that these salts effectively act as Lewis acids or it may be that they are in themselves capable of promoting an ion-exchange mechanism at the surface of the solid particles.

It is preferable to choose a salt which has a cation which is different from and especially, more electropositive than, any cation of the major part of the solids. However, in some situations this does not always apply. Also, it is preferable that the anion of the salt deflocculant is soluble in the liquid phase. Thus, for example, when the solids mainly comprise alkali metal salts, it is desirable to select a salt of a transition metal, such as ferric or manganese chloride.

It is also preferred to choose salts having at least one moiety with a good complex forming ability, for example a quaternary ammonium ion or an appropriate transition metal ion. This is perhaps the reason why the particular salts mentioned in the preceding paragraph tend to produce the required deflocculant effect.

The salts with good complex forming ability do however sometimes (perhaps by virtue of that property) tend to result in setting (solidification) in the longer term, despite initially causing deflocculation. Thus in some cases, they are best used in combination with surfactant deflocculants of the kind to be described hereinafter.

Another preferred class of salts for this purpose are the alkali-metal sulphosuccinate di-alkyl derivatives such as that sold under the trade name Aerosol OT. When these are used, it may be necessary to heat the product to initiate deflocculation. Di-alkyl sulphosuccinate salts which may be used also include those described in specification EP-A-208,440 which include ammonium as well as alkali-metal salts. The free acid di-alkyl sulphosuccinate acids may also be used. It is further possible to use the substantially anhydrous aluminosilicates (including zeolites) as deflocculants.

These are sometimes referred to an 'activated' types. One such is 'activated zeolite 4A' sold by Degussa. These are even capable of deflocculating partially or fully hydrated aluminosilicates. Although network formation is promoted by trace quantities of water in the composition and it could be said that the substantially anhydrous aluminosilicates merely absorb this, that may not be the primary effect because the same behaviour has not been observed using anhydrous calcium chloride which has a very marked water-absorbing capability.

It is also possible to use salts with organic cations.

When the liquid phase comprises a liquid surfactant a particularly preferred class of deflocculants comprises synthetic anionic surfactants. Although anionics which are salts of alkali or other metals may be used, (especially having regard to the aforementioned desirable relative electropolarities of the solids and deflocculant cations), particularly preferred are the free acid forms of these surfactants (wherein the metal cation is replaced by an K+ cation, i.e. proton). These anionic surfactants include all those classes, sub-classes and specific forms described in the aforementioned general references on surfactants, viz, Schwartz & Perry, Schwartz Perry and Berch, McCutcheon's, Tensid-Taschenbuch; and the free acid forms thereof. Many anionic surfactants have already been described hereinbefore.In the role of deflocculants, the free acid forms of these are generally preferred.

In particular, some preferred sub-classes and examples are the C8-C18 alkylbenzene sulphonic acids, the C10-Cl8 alkyl- or alkylether sulphuric acid monoesters, the C12-C18 paraffin sulphonic acids, the fatty acid sulphonic acids, the benzene-, toluene-, xylene- and cumene sulphonic acids and so on. Particularly, although not exclusively, preferred are the linear C12-C18 alkylbenzene sulphonic acids.

As well as anionic surfactants, zwitterionic-types can also be used as deflocculants. These may be any described in the aforementioned general surfactant references. One preferred example is lecithin.

LEVEL OF DEFLOCCULANT The level of the deflocculant material in the composition can be optimised by the means described in the aforementioned EP-A-266199, but in very many cases is at least 0.01%, usually 0.1% and preferably at least 1% by weight, and may be as high as 15% by weight. For most practical purposes, the amount ranges from 2-12%, preferably from 4-10% by weight, based on the final composition.

OTHER INGREDIENTS In addition to the components already discussed, there are very many other ingredients which can be incorporated in liquid cleaning compositions.

There is a very great range of such other ingredients and these will be chosen according to the intended use of the product. However, the greatest diversity is found in products for fabrics washing and/or conditioning. Many ingredients intended for that purpose will also find application in products for other applications (e.g. in hard surface cleaners and warewashing liquids).

DETERGENCY BUILDERS The detergency builders are those materials which counteract the effects of calcium, or other ion, water hardness, either by precipitation or by an ion sequestering effect. They comprise both inorganic and organic builders. They may also be sub-divided into the phosphorus-containing and non-phosphorus types, the latter being preferred when environmental considerations are important.

In general, the inorganic builders comprise the various phosphate-, carbonate-, silicate-, borate- and aluminosilicates-type materials, particularly the alkali-metal salt forms. Mixtures of these may also be used.

Examples of phosphorus-containing inorganic builders, when present, include the water-soluble salts, especially alkali metal pyrophosphates, orthophosphates, polyphosphates and phosphonates. Specific examples of inorganic phosphate builders include sodium and potassium tripolyphosphates, phosphates and hexametaphosphates.

Examples of non-phosphorus-containing inorganic builders, when present, include water-soluble alkali metal carbonates, bicarbonates, borates, silicates, metasilicates, and crystalline and amorphous aluminosilicates. Specific examples include sodium carbonate (with or without calcite seeds), potassium carbonate, sodium and potassium bicarbonates, silicates and zeolites.

The aluminosilicates are an especially preferred class of non-phosphorus inorganic builders. These for example are crystalline or amorphous materials having the general formula: Naz (AlO2)z (SiO2)y . x H2O wherein z and y are integers of at least 6, the molar ratio of z to y is in the range from 1.0 to 0.5, and x is an integer from 6 to 189 such that the moisture content is from about 4% to about 20% by weight (termed herein, 'partially hydrated'). This water content provides the best rheological properties in the liquid. Above this level (e.g. from about 19% to about 28% by weight water content), the water level can lead to network formation.

Below this level (e.g. from 0 to about 6% by weight water content), trapped gas in pores of the material can be displaced which causes gassing and tends to lead to a viscosity increase also. The preferred range of aluminosilicate is from about 12% to about 30% on an anhydrous basis. The aluminosilicate preferably has a particle size of from 0.1 to 100 microns, ideally between 0.1 and 10 microns and a calcium ion exchange capacity of at least 200 mg calcium carbonate/g.

Examples of organic builders include the alkali metal, ammonium and substituted ammonium, citrates, succinates, malonates, fatty acid sulphonates, carboxymethoxy succinates, ammonium polyacetates, carboxylates, polycarboxylates, aminopolycarboxylates, polyacetyl carboxylates and polyhydroxsulphonates.

Specific examples include sodium, potassium, lithium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid, nitrilotriacetic acid, oxydisuccinic acid, melitic acid, benzene polycarboxylic acids and citric acid. Other examples are organic phosphonate type sequestering agents such as those sold by Monsanto under the tradename of the Dequest range and alkanehydroxy phosphonates.

Other suitable organic builders include the polymers and co-polymers known to have builder properties, for example appropriate polyacrylic acid, polymaleic acid and polyacrylic/polymaleic acid co-polymers and their salts, such as those sold by BASF under the Sokalan Trade Mark.

THE BLEACH SYSTEM Bleaches include the halogen, particularly chlorine bleaches such as are provided in the form of alkalimetal hypohalites, e.g. hypochlorites. In the application of fabrics washing, the oxygen bleaches are preferred, for example in the form of an inorganic persalt, preferably with a bleach precursor, or as a peroxy acid compound.

In the case of the inorganic persalt bleaches, the activator makes the bleaching more effective at lower temperatures, i.e. in the range from ambient temperature to about 600C, so that such bleach systems are commonly known as low-temperature bleach systems and are well known in the art. The inorganic persalt such as sodium perborate, both the monohydrate and the tetrahydrate, acts to release active oxygen in solution, and the activator is usually an organic compound having one or more reactive acyl residues, which cause the formation of peracids, the latter providing for a more effective bleaching action at lower temperatures than the peroxybleach compound alone.

The ratio by weight of the peroxybleach compound to the activator is from about 20:1 to about 2:1, preferably from about 10:1 to about 3.5:1. Whilst the amount of the bleach system, i.e. peroxybleach compound and activator, may be varied between about 5% and about 35% by weight of the total liquid, it is preferred to use from about 6% to about 30% of the ingredients forming the bleach system.

Thus, the preferred level of the peroxybleach compound in the composition is between about 5.58 and about 27% by weight, while the preferred level of the activator is between about 0.5% and about 14%, most preferably between about 1% and about 5% by weight.

Typical examples of the suitable peroxybleach compounds are alkalimetal perborates, both tetrahydrates and monohydrates, alkali metal percarbonates, persilicates and perphosphates, of which sodium perborate is preferred.

PEROXYBLEACH ACTIVATORS Activators for peroxybleach compounds have been amply described in the literature, including in British patent specifications 836,988, 855,735, 907,356, 907,358, 907,950, 1,003,310, and 1,246,339, US patent specifications 3,332,882, and 4,128,494, Canadian patent specification 844,481 and South African patent specification 68/6,344.

The exact mode of action of such activators is not known, but it is believed that peracids are formed by reaction of the activators with the inorganic peroxy compound, which peracids then liberate active-oxygen by decomposition.

They are generally compounds which contain N-acyl or O-acyl residues in the molecule and which exert their activating action on the peroxy compounds on contact with these in the washing liquor.

Typical examples of activators within these groups are polyacylated alkylene diamines, such as N,N,N1 1 ,N -tetraacetylethylene diamine (TAED) and N,N,N,N -tetraacetylmethylene diamine (TAMD); acylated glycolurils, such as tetraacetylgylcouril (TAGU); triacetylcyanurate and sodium sulphophenyl ethyl carbonic acid ester.

A particularly preferred activator is N,N,N -tetra- acetylethylene diamine (TAED).

The activator may be incorporated as fine particles or even in granular form, such as described in the applicants' UK patent specification GB 2,053,998 A.

Specifically, it is preferred to have an activator of an average particle size of less than 150 microns, which gives significant improvement in bleach efficiency. The sedimentation losses, when using an activator with an average particle size of less than 150 microns, are substantially decreased. Even better bleach performance is obtained if the average particle size of the activator is less than 100 microns. However, too small a particle size can give increased decomposition and handling problems prior to processing. However, these particle sizes have to be reconciled with the requirements for dispersion in the liquid phase (it will be recalled that the aforementioned first product from requires particles which are as small as possible within practical limits).

Liquid activators may also be used, e.g. as hereinafter described.

ORGANIC PEROXYACID BLEACHES The organic peroxyacid compound bleaches (which in some cases can also act as deflocculants) are preferably those which are solid at room temperature and most preferably should have a melting point of at least 500C.

Most commonly, they are the organic peroxyacids and water-soluble salts thereof having the general formula

wherein R is an alkylene or substituted alkylene group containing 1 to 20 carbon atoms or an arylene group containing from 6 to 8 carbon atoms, and Y is hydrogen, halogen, alkyl, aryl or any group which provides an anionic moiety in aqueous solution. Such Y groups can include, for example:

wherein M is H or a water-soluble, salt-forming cation.

The organic peroxyacids and salts thereof usable in the present invention can contain either one, two or more peroxy groups and can be either aliphatic or aromatic.

When the organic peroxyacid is aliphatic, the unsubstituted acid may have the general formula:

wherein Y can be H, -CH3, -CH2C1,

and n can be an integer from 60 to 20.

Peroxydodecanoic acids, peroxytetradecanoic acids and peroxyhexadecanoic acids are the most preferred compounds of this type, particularly 1,12-diperoxydodecandioic acid (sometimes known as DPDA), 1,14-diperoxytetradecandioic acid and 1,16-diperoxyhexadecandioic acid. Examples of other preferred compounds of this type are diperoxyazelaic acid, diperoxyadipic and diperoxysebacic acid.

When the organic peroxyacid is aromatic, the unsubstituted acid may have the general formula:

wherein Y is, for example hydrogen, halogen, alkyl,

The percarboxy and Y groupings can be in any relative position around the aromatic ring. The ring and/or Y group (if alkyl) can contain any non-interfering substituents such as halogen or sulphonate groups.

Examples of suitable aromatic peroxyacids and salts thereof include monoperoxyphthalic acid, diperoxyterephthalic acid, 4-chlorodiperoxyphthalic acid, diperoxyisophthalic acid, peroxybenzoic acids and ring-substituted peroxybenzoic acids, such as peroxy-alpha-naphthoic acid. A preferred aromatic peroxyacid is diperoxyisophthalic acid.

OTHER BLEACHES Another preferred class of peroxygen compounds which can be incorporated to enhance dispensing/dispersibility in water are the anhydrous perborates described for that purpose in the applicants' European patent specification EP-A-217,454.

BLEACH STABILISER It is particularly preferred to include in the compositions, a stabiliser for the bleach or bleach system, for example ethylene diamine tetramethylene phosphonate and diethylene triamine pentamethylene phosphonate or other appropriate organic phosphonate or salt thereof, such as the Dequest range hereinbefore described. These stabilisers can be used in acid or salt form, such as the calcium, magnesium, zinc or aluminium salt form. The stabiliser may be present at a level of up to about 1% by weight, preferably between about 0.18 and about 0.5% by weight.

LIQUID BLEACH PRECURSORS The applicants have also found that liquid bleach precursors, such as glycerol triacetate and ethylidene heptanoate acetate, isopropenyl acetate and the like, also function suitably as a material for the liquid phase, thus obviating or reducing any need of additional relatively volatile solvents, such as the lower alkanols, paraffins, glycols and glycolethers and the like, e.g. for viscosity control.

ABRASIVES The third category of major other ingredients are abrasives, particularly for incorporation in hard surface cleaners (liquid abrasive cleaners). These will inevitably be incorporated as particulate solids. They may be those of the kind which are water insoluble, for example calcite. Suitable materials of this kind are disclosed in patent specifications EP-A-50,887; EP-A-80,221; EP-A-140,452; EP-A-214,540 and EP 9,942 (all Unilever), which relate to such abrasives when suspended in aqueous media.

The abrasives may also be water soluble, especially in the form of particles of any solid water soluble salt hereinafter described, for example as an inorganic builder. Inert particulate solid salts having no particular function in fabrics washing, other than as bulking agents in detergent powders, e.g. sodium sulphate, may also be used for this purpose. Especially preferred are the water soluble abrasives described in the applicants' patent specification EP-A-193,375.

MISCELLANEOUS OTHER INGREDIENTS Other ingredients comprise those remaining ingredients which may be used in liquid cleaning compositions, such as fabric conditioning agents, enzymes, perfumes (including deoperfumes), micro-biocides, colouring agents, fluorescers, soil-suspending agents (anti-redeposition agents), corrosion inhibitors, enzyme stabilising agents, and lather depressants.

Amongst the fabric conditioning agents which may be used, either in fabric washing liquids or in rinse conditioners, are, in addition to the soap, fabric softening materials such as fabric softening clays, quaternary ammonium salts, imidazolinium salts, fatty amines and cellulases.

Enzymes which can be used in liquids according to the present invention include proteolytic enzymes, amylolytic enzymes and lipolytic enzymes (lipases). Various types of proteolytic enzymes and amylolytic enzymes are known in the art and are commercially available. They may be incorporated as "prills" or "marumes" etc.

The fluorescent agents which can be used in the liquid cleaning compositions according to the invention are well known and many such fluorescent agents are available commercially. Usually, these fluorescent agents are supplied and used in the form of their alkali metal salts, for example, the sodium salts. The total amount of the fluorescent agent or agents used in a detergent composition is generally from 0.02-2% by weight.

When it is desired to include anti-redeposition agents in the liquid cleaning compositions, the amount thereof is normally from about 0.1% to about 5% by weight, preferably from about 0.2% to about 2.58 by weight of the total liquid composition. Preferred anti-redeposition agents include carboxy derivatives of sugars and celluloses, e.g. sodium carboxymethyl cellulose, anionic poly-electrolytes, especially polymeric aliphatic carboxylates, or organic phosphonates.

One preferred class anti-corrosion agents which may be used comprises finely divided silicas. In such systems, they will generally be used at no more than 2% by weight of the total product, especially less than 1%.

Other preferred corrosion inhibitors are alkali metal silicates, particularly sodium ortho-, meta- or preferably neutral or alkaline silicate, e.g. at levels of at least about 1%, and preferably from about 5% to about 158 by weight of the total liquid product.

WATER LEVEL The compositions are substantially non-aqueous, i.e.

they contain little or no free water, preferably no more than 5%, preferably less than 3%, especially less than 1% by weight of the total composition. It has been found that the higher the water content, the more likely it is for the viscosity to be too high, or even for setting to occur. However, this may at least in part be overcome by use of higher amounts of, or more effective deflocculants.

Since the objective of a non-aqueous liquid will generally be to enable the formulator to avoid the negative influence of water on the components, e.g.

causing incompatibility of functional ingredients, it is clearly necessary to avoid the accidental or deliberate addition of water to the product at any stage in its life.

For this reason, special precautions are necessary in manufacturing procedures and pack designs for use by the consumer.

PROCESSING During manufacture, it is preferred that all raw materials should be dry and (in the case of hydratable salts) in a low hydration state, e.g. anhydrous phosphate builder, sodium perborate monohydrate and dry calcite abrasive, where these are employed in the composition. In a preferred process, the dry, substantially anhydrous solids, other than the soap and that part of the liquid phase which is used to form the pre-dispersion, are blended with the liquid phase in a dry vessel. In order to minimise the rate of sedimentation of the solids, this blend is passed through a grinding mill or a combination of mills, e.g. a colloid mill, a corundum disc mill, a horizontal or vertical agitated ball mill, to achieve a particle size of 0.1 to 100 microns, preferably 0.5 to 50 microns, ideally 1 to 10 microns.A preferred combination of such mills is a colloid mill followed by a horizontal ball mill since these can be operated under the conditions required to provide a narrow size distribution in the final product. Of course particulate material already having the desired particle size need not be subjected to this procedure and if desired, can be incorporated during a later stage of processing.

During this milling procedure, the energy input results in a temperature rise in the product and the liberation of air entrapped in or between the particles of the solid ingredients. It is therefore highly desirable to mix any heat sensitive ingredients into the product after the milling stage and a subsequent cooling step. It may also be desirable to de-aerate the product before addition of these (usually minor) ingredients and optionally, at any other stage of the process. Typical ingredients which might be added at this stage are perfumes and enzymes, but might also include highly temperature sensitive bleach components which may be desirable in the final composition. Suitable equipment for cooling (e.g. heat exchangers) and de-aeration will be known to those skilled in the art.

It follows that all equipment used in this process should be completely dry, special care being taken after any cleaning operations. The same is true for subsequent storage and packing equipment.

PACKAGING The packaging for the product should also minimise the risk of water being introduced to the product.

Particularly suitable designs for this purpose have been described in South African patent application 87/2272 in which the product is charged to a unit dosing chamber which communicates with the body of the container before the cap is removed. A further pack option which is especially suitable for some classes of product which could be formulated with non-aqueous liquid (e.g. fabric washing detergents or warewashing products) incorporates a unit dose of the product, e.g. in a sachet or a small pot with a tear-open device. After opening, the entire contents of such a pack would then be consumed in a single use of the product.

Containers with pump-action dispensers may also be used since these will allow product to be removed whilst effectively preventing entry of water.

The invention will now be better explained by way of the following examples.

EXAMPLES 1 TO 4 various processes were employed to prepare a non-aqueous liquid detergent composition having the following formulation.

Nonionic surfactant 36.7 or 35.7 Glycerol triacetate (GTA) 12.0 Sodium stearate soap 0 or 1.0 Sodium perborate monohydrate 13.0 Sodium carbonate 24.0 Calcite (SOCAL U3) 5.0 Alkyl benzene sulphonic acid 3.0 Minor ingredients balance The nonionic detergent active was LIALETT 111-7. In this formulation the nonionic detergent active and the GTA are liquid phase ingredients.

In a first experiment, the soap was added together with all other ingredients to a ball mill, the mill was operated to reduce the particle size of the solid phase ingredients to an average of 7 microns. The viscosity of the product was measured initially and again after 1 week storage at 200C. A second experiment omitted the soap to provide comparison data. In a third experiment, the soap was premixed at room temperature with part of the nonionic surfactant at a concentration of 158 and then added to the product after the ball milling stage. In a further experiment a pre-dispersion of the soap in powder form in the nonionic surfactant was formed with a concentration of 15% by dispersing the soap at 1300C, holding at that temperature for at least 20 minutes and allowing the pre-dispersion to cool to below 400C before adding to the ball-milled product. The results of these experiments were: Viscosity Example Soap Initial 1 week 1* Mixed with other 5665 6220 ingredients 2* None 2160 1195 3* Pre-dispersion at r/t 3135 3635 4 Pre-dispersion at 1300 2100 1930 Notes: 1 - viscosity was measured at 250C using a shear rate of 21s . The units are mPa.s.

* - comparative example.

These experiments show that two methods of incorporating soap both lead to unacceptable products, but that when the pre-dispersion is prepared at the elevated temperature, a product with properties similar to that of the soap-free product was obtained, ie. a product having a satisfactorily low viscosity which does not increase on storage.

EXAMPLES 5 TO 8 Example 4 was repeated with a range of formulations with the following results Example No. 4 5 6 7 8* Lialett 111-7 40.7 22.7 22.7 39.7 42.7 Imbentin - 18.0 17.0 GTA 10.9 10.9 10.9 10.9 10.9 Sodium stearate 2.0 2.0 3.0 3.0 Sodium perborate 11.8 11.8 11.8 11.8 11.8 Sodium carbonate 21.7 21.7 21.7 21.7 21.7 Calcite (SOCAL U3) 4.6 4.6 4.6 4.6 4.6 ABSA 2.7 2.7 2.7 2.7 2.7

Minor ingredients < ------------ balance ---------- > Viscosity (250C, 21s 1) 1005 840 1210 1075 640 Appearance liq liq liq liq liq These results show that products with satisfactory properties can be obtained by the method according to the invention.

EXAMPLES 9 TO 12 These examples demonstrate the effect of the nature of the soap and the nature of the nonionic surfactant on the physical properties of the product.

The sodium stearate soap samples used were derived from fatty acids which according to analysis had the following composition.

Sample U F C16 saturated 30.0 55.9 C18 saturated 62.3 37.0 Total unsaturated 1.4 1.6 These soaps therefore differed primarily in the ratio of C16 to C18 fatty acids.

The nonionic surfactant samples were Lialett 111-7 and Imbentin.

Using these soaps and nonionic surfactants, Example 7 was repeated with the following results. In each case the viscosity of the pre-dispersion of soap in the nonionic surfactant was also measured.

Pre Soap dispersion Product Example Nonionic Sample Viscosity Viscosity (after 1 week) 9 Lialett 111-7 U 332 1185 10 Lialett 111-7 F 722 1610 11 Imbentin U 1450 1565 12 Imbentin F 3115 2335 These results show that the viscosity of the final product is related to the viscosity of the pre-dispersion, that Lialett 111-7 is a preferred nonionic surfactant and that sample U soap is a preferred soap.

EXAMPLE 13 Example 4 was repeated with the exception that the pre-dispersion was prepared by heating to 900C. The results were: Viscosity1 Example Soap Initial 1 week 4 Pre-dispersion at 1300 2100 1930 13* Predispersion at 900 4415 4110 This example illustrates the importance of heating the predispersion to a temperature above 1000C.

EXAMPLE 14 Using soap sample U, a 15% pre-dispersion in Imbentin was prepared by heating to 900C and then cooling to below 400C. The viscosity of this pre-dispersion was in excess of 15,000 mPa.s ie. significantly higher than the 1450 mPa.s obtained by heating to 1300C. This example also illustrates the importance of heating the pre-dispersion to a temperature above 1000C.

Claims (5)

1. A method of producing a stable, pourable non-aqueous liquid cleaning composition comprising a liquid phase and a dispersed particulate solid phase and containing up to 10% by weight soap, the method comprising the steps of: i) contacting the soap with at least one liquid phase ingredient, at a temperature above 1000C to form a pourable liquid pre-dispersion containing from 3% to 20% by weight soap; and thereafter ii) mixing the soap pre-dispersion with the particulate solid phase and optionally further liquid phase ingredients.

2. A method according to Claim 1, wherein the soap pre-dispersion contains from 10% to 15% soap.

3. A method according to Claim 1, wherein the soap pre-dispersion is cooled to a temperature below 300C before step (ii).

4. A method according to Claim 1, wherein the particulate solid phase is dispersed in further liquid phase ingredients by milling and the cooled soap pre-dispersion is added thereafter.

5. A stable pourable non-aqueous liquid cleaning composition comprising a liquid phase and a dispersed solid phase, the composition containing from 0.5% to 10% by weight of soap and being substantially free of solvents for the soap.