GB2200921A - Thixotropic clay aqueous suspensions containing fatty acid metal salts and potassium polyphosphates stabilizers - Google Patents

Description

2 z 200921 9 "THIXOTROPIC CLAY AQUEOUS SUSPENSIONS CONTAINING FATTY ACID

METAL SALTS AND POTASSIUM POLYPHOSPHATES STABILIZERS" The present invention relates to thixotropic clay aqueous suspension with improved physical stability.

More specifically the invention relates to the use of potassium polyphosphates and metal salts of long chain fatty acids as physical stabilizers for thixotropic clay aqueous suspensions.

The addition of small effective amounts of potassium polyphosphates and small effective amounts of polyvalent metal salts of long chain fatty acids significantly improves the physical stability and rheo- logical properties variations with time of thixotropic clay aqueous suspensions detergent compositions The thixotropic properties can be retained or' improved using smaller levels, such as 0 25 to 0 50 %, of the, clay thixotropic thickener than in the absence of the potassium polyphosphate stabilizer.

The present invention specifially relates to automatic dishwashing detergent compositions having thixotropic properties, improved chemical and physical stability, improve stability against variations in rheological properties with time, and with increased apparent viscosity, and which are readily dispersible in the washing medium to provide effective cleaning of dishware, glassware, china and the like.

Commercially available household-machine dish- washer detergents provided in powder form have several disadvantages, e g non-uniform composition; costly operations necessary in their manufacture; tendency to cake in storage at high humidities, resulting in the formation of lumps which are difficult to disperse; dustiness, a source of particular irritation to users who suffer allergies; and tendency to cake in the dish- washer machine dispenser.

Recent research and development activity has focussed on the gel or "thixotropic" form of such compositions, e g scouring cleansers and automatic- dishwasher products characterised as thixotropic pastes Dishwasher products so provided are primarily objectionable in that they are insufficiently viscous to remain "anchored" in the dispenser cup of the dishwasher Ideally, thixotropic cleaning compositions should be highly viscous in a quiescent state, Bingham plastic in nature, and have relatively high yield values When subjected to shear stresses, however, such as being shaken in a container or squeezed through an orifice, they should quickly fluidize and, upon cessation of the applied shear stress, quickly revert to the high viscosity/Bingham plastic state Stability is likewise of primary importance, i e there should be no significant evidence of phase separation or leaking after long standing.

U.S Patent Application Serial No 744,754 filed 14th June, 1985 corresponding to G B Application No.

Serial No 2176495 which is assigned to the applicants, is directed to thixotropic clay aqueous suspension dishwashing detergent compositions contain- ing aluminium stearate as physical stabilizing agent.

These compositions show improvement in the physical stability of the detergent composition and improvement against phase separation over those clay containing compositions that do not contain the aluminium stearate These formulations of U S Serial No.

744,754, however, have in some instances experienced difficulty in achieving stability against variations in rheological properties with time and over wide temperature changes and have generally required rela- tively high clay content, such as 0 25 to 2 0 %.

The provision of automatic-dishwasher compositions in gel form having the aforedescribed properties, other than for the improvements described in the above- mentioned application U S Serial No 744,754, has thus far proven problematical, particularly as regards compositions for use in home dishwasher machines For effective use, it is generally recommended that the automatic dishwashing detergent, hereinafter also designated ADD, contain ( 1) sodium tripolyphosphate (Na TPP) to soften or tie up hard-water minerals and to emulsify and/or peptize soil; ( 2) sodium silicate to supply the alkalinity necessary for effective detergency and to provide protection for fine china glaze and pattern; ( 3) sodium carbonate, generally considered to be optional, to enhance alkalinity; ( 4) a chlorine-releasing agent to aid in the elimination of soil specks which lead to water spotting; and ( 5) defoamer/surfactant to reduce foam, thereby enhancing machine efficiency and supplying requisite detergency.

See, for example, SDA Detergents in Depth, "Formula- tions Aspects of Machine Dishwashing", Thomas Oberle ( 1974) Cleansers approximating to the aforedescribed compositions are mostly liquids or powders Combining such ingredients in a gel form effective for home- machine use has proved difficult Generally, such compositions omit hypochlorite bleach, since it tends to react with other chemically active ingredients, particularly surfactant Thus, U S Patent 4,115,308 discloses thixotropic automatic dishwasher pastes containing a suspending agent, e g CMC, synthetic clays or the like; inorganic salts including silicates, phosphates and polyphosphates; a small amount of surfactant and a suds depressor Bleach is not disclosed U S Patent No 4,147,650 is somewhat similar, optionally including chlorine (hypochlorite) bleach but no organic surfactant or foam depressant The product is described, moreover, as a detergent slurry with no apparent thixotropic properties.

U.S Patent No 3,985,668 describes abrasive scouring cleaners of gel-like consistency containing ( 1) suspending agent, preferably the Smectite and attapulgite types of clay; ( 2) abrasive, e g silica sand or perlite; and ( 3) filler comprising light density powdered polymers, expanded perlite and the- like, which has a buoyancy and thus stabilizing effect on the composition in addition to serving as a bulking agent, thereby replacing water otherwise available for undesired supernatant layer formation due to leaking and phase destabilization The foregoing are the essential ingredients Optional ingredients include hypochlorite bleach, bleach stable surfactant and buffer, e g silicates, carbonates, and monophosphates.

Builders, such as Na TPP, can be included as further optional ingredients to supply or supplement building function not provided by the buffer, the amount of such builder not exceeding 5 % of the total composition, according to the patent Maintenance of the desired (greater than) p H 10 levels is achi ved by the buffer/builder components High p H is said to minimize decomposition of chlorine bleach and undesired inter- action between surfactant and bleach When present, Na TPP is limited to 5 %, as stated Foam killer is not disclosed.

In U K Patent Application GB 2,116,199 A and GB 2,140,450 A, both of which are assigned to Colgate- Palmolive, liquid ADD compositions are disclosed which have properties desirably characterizing thixotropic, gel-type structure and which include each of the various ingredients necessary for effective detergency with an automatic dishwasher The normally gel-like aqueous automatic dishwasher detergent composition having thixotropic properties includes the following ingredients, on a weight basis:

(a) 5 to 35 % alkali metal tripolyphosphate; (b) 2 5 to 20 % sodium silicate; (c) 0 to 9 % alkali metal carbonate; (d) 0 1 to 5 % chlorine bleach stable, water dispersible organic detergent active material; (e) 0 to 5 % chlorine bleach stable foam depressant; (f) chlorine bleach compound in an amount t-o provide about 0 2 to 4 % of available chlorine; (g) thixotropic thickener in an amount sufficient to provide the composition with thixotropy index of about 2 5 to 10; (h) sodium hydroxide, as necessary, to adjust p H; and (i) balance water.

ADD compositions so formulated are low-foaming; are readily soluble in the washing medium and most effective at p H values best conducive to improved cleaning performance, viz, p H 10 5-14 0 The composi- tions are normally of -gel consistency, i e a highly viscous, opaque jelly-like material having Bingham plastic character and thus relatively high yield values Under such conditions, the composition is quickly fluidized and easily dispersed When the shear force is discontinued, the fluid composition quickly reverts to a high viscosity, Bingham plastic state closely approximating its prior consistency.

U.S Patent 4,511,487 dated 14th April, 1985 describes a low-foaming detergent paste for dishwashers The patented thixotropic cleaning agent has a viscosity of at least 30 Pa S at 200 C as deter- mined with a rotational viscometer at a spindle speed of 5 revolutions per minute The composition is based on a mixture of finely divided hydrated sodium metasilicate, an active chlorine compound and a thickening agent which is a foliated silicate of the hectorite type Small amount of nonionic tensides and alkali metal carbonates and/or hydroxides may be used.

The formation of organoclays by the interaction of clays (such as bentonite and hectorite) with organic compounds such as quaternary ammonium salts, has also been described (W S Mardis, JAOCS, Vol 61, No 2, p.382 ( 1984)).

While these previously disclosed liquid ADD formulations are not subject or are subject to a lesser degree to one or more of the above described deficiencies, it has been found that further improve- ments in physical stability and stability against variations in rheological properties with time are desired to increase the shelf-life of the product and thereby enhance consumer acceptance.

At the same time it would be highly desirable to increase the physical stability and stability against variations in rheological properties with time of other clay based thixotropic liquid formulations, such as scouring cleansers; dental pastes, "liquid" soaps, and the like.

Accordingly, the invention aims to provide anti- settling additives for thixotropic clay aqueous suspensions.

The invention also aims to provide liquid ADD compositions having thixotropic properties with improved physical stability and improved stability against variations in rheological properties with time.

The invention also aims to provide thixotropic liquid ADD compositions having reduced levels of thixo- tropic thickener without adversely effecting the generally high viscosities at low shear rates and lower viscosities at high shear rates which are character- istics of the desired thixotropic properties.

This invention also aims to improve the stability of aqueous thixotropic clay based compositions, especially liquid automatic dishwasher detergent pastes or gels, by incorporating in the clay aqueous suspen- sion a minor amount of potassium polyphosphates and a minor amount of a fatty acid metal salt effective to inhibit the settling of the suspended particles and to prevent phase separation.

This invention further aims to improve the stability against variations in rheological properties with time -of aqueous thixotropic clay based compositions, especially liquid automatic dishwasher detergent pastes or gels, by incorporating in the clay aqueous suspension a small effective amount of potassium polyphosphates and a small effective amount of a fatty acid metal salt as stabilizing agents.

According to the present invention there is incorporated in a normally gel-like aqueous liquid composition a small but effective amount of physical stabilizers which are potassium polyphosphates and a long chain fatty acid metal salt More particularly, according to a preferred and specific embodiment of the invention, there is provided a normally gel-like auto- matic dishwasher detergent compositin in which is incorporated an amount of potassium polyphosphates and an amount of a metal salt of a long chain fatty acid which are effective to reduce variations in rheological properties with time and effective to inhibit settling of the suspended particles, such as thixotropic agent and sodium tripolyphosphate builder salt.

In accordance with these particular aspects, the present invention provides a normally gel-like aqueous automatic dishwasher detergent composition having thixotropic properties which include, on a weight basis:

(a) 5 to 35 % sodium tripolyphosphate; (b) 2 5 to 20 % sodium silicate; (c) 0 to 9 % alkali metal carbonate; (d) 0 1 to 5 % chlorine bleach stable, water dispersible organic detergent active material; (e) 0 to 5 % chlorine bleach stable foam depressant; (f) chlorine bleach compound in an amount to provide about 0 2 to 4 % of available chlorine; (g) thixotropic thickener in an amount sufficient to provide the compositin with thixotropy index of about 2 5 to 10; and (h) 0 to 8 % sodium hydroxide; (i) potassium polyphosphates and a polyvalent metal salt of a long chain fatty acid in amounts effective to increase the physical stability of the composition and the physical stability of the composi- tion against variations in rheological properties with time; and (j) balance water.

Also related to this specific aspect, the invention provides a-method for cleaning dishware in an automatic dishwashing machine with an aqueous wash bath containing an effective amount of the liquid automatic dishwasher detergent (LADD) composition as described- above According to this aspect of the invention, the LADD composition can be readily poured into the dispensing cup of the automatic dishwashing machine and will, within just a few seconds, promptly thicken to its normal gel-like or pasty state.

Generally, LADD effectiveness is directly related to (a) available chlorine levels; (b) alkalinity; (c) solubility in washing medium; and (d) foam inhibition.

It is preferred herein that the p H of the LADD composi- tion be at least about 9 5, more preferably from about 10.5 to 14 0 and most preferably at least about 11 5.

The presence of carbonate is also often needed herein, since, it acts as a buffer helping to maintain the desired p H level Excess carbonate is to be avoided, however, since it may cause the formation of needle- like crystals of carbonate, thereby impairing the stability, thixotropy and/or detergency of the LADD product, as well as impairing the dispensibility of the product from, for example, squeeze tube bottles.

Caustic soda (Na OH) serves the further function of neutralizing the phosphoric or phosphonic acid ester foam depressant when present About 0 5 to 6 weight percent of Na OH and about 2 to 9 weight percent of sodium carbonate in the LADD composition are typical, although it should be noted that sufficient alkalinity may be provided by the Na TPP and sodium silicate.

The Na TPP employed in the LADD composition in a range of about 8 to 35 weight percent, preferably about to 30 weight percent, should preferably be free of heavy metal which tends to decompose or inactivate the preferred sodium hypochlorite and other chlorine bleach compounds The Na TPP may be anhydrous or hydrated, including the stable hexahydrate with a degree of hydration of 6 corresponding to about 18 % by weight of water or more Especially preferred LADD compositions are obtained, for example, when using a 0 5:1 to 2:1 weight ratio of anhydrous to hexahydrated Na TPP, values of about 1:1 being particularly preferred.

Foam inhibition is important to increase dish- washer machine efficiency and minimize destabilizing effects which might occur due to the presence of excess foam within the washer during use Foam may be sufficiently reduced by suitable selection of the type and/or amount of detergent active material, the main foam-producing component The degree of foam is also somewhat dependent on the hardness of the wash water in the machine whereby suitable adjustment of the propor- tions of Na TPP which has a water softening effect may aid in providing the desired degree of foam inhibition.

However, it is generally preferred to include a chlorine bleach stable foam depressant or inhibitor.

Particularly effective are the alkyl phosphonic acid esters of the formula HO-P-R I OR available for example from BASF-Wyandotte (PCUK-PAE), and especially the alkyl acid phosphate esters of the formula 0 HO-P-OR I OR available, for example, from Hooker (SAP) and Knapsack (LP Kn-158), in which one or both R groups in each type of ester may represent independently a C 12-20 alkyl group Mixtures of the two types, or any other chlorine bleach stable types, or mixtures of mono and di-esters of the same type, may be employed.

Especially preferred is a mixture of mono and di-C 16- 18 alkyl acid phosphate esters such as monostearyl/di- stearyl acid phosphates 1 2/1 (Knapsack) or (UGINE KULHMAN) When employed, proportions of 0 1 to 5 weight percent, preferably about 0 1 to 0 5 weight percent, of foam depressant in the composition is typical, the weight ratio of detergent active component (d) to foam depressant (e) generally ranging from about 10:1 to 1:1 and preferably about 5:1 to 1:1 Other defoamers which may be used include, for example, the known silicones In addition, it is an advantageous feature of this invention that many of the stabilizing salts, such as the stearate salts, for example, aluminium stearate, are also effective as foam killers.

c;.

Although any chlorine bleach compound may be employed in the compositions of this invention, such as dichloro-isocyanurate, dichloro-dimethyl hydantoin, or chlorinated TSP, alkali metal, e g potassium, lithium, magnesium and especially sodium, hypochlorite is preferred The compositionshould contain sufficient chlorine bleach compound to provide about 0 2 to 4 0 % by weight of available chlorine, as determined, for example, by acidification of 100 parts of the composition with excess of hydrochloric acid A solution containing about 0 2 to 4 0 % by weight of sodium hypochlorite contains or provides roughly the same percentage of available chlorine About 0 8 to 1.6 % by weight of available chlorine is especially preferred For example, sodium hypochlorite (Na O Cl) solution of from about 11 to about 13 % available chlorine in amounts of about 3 to 20 %; preferably about 7 to 12 %, can be advantageously used.

The sodium silicate which provides alkalinity and protection of hard surfaces, such as fine china glaze and pattern, is employed in an amount ranging from about 2 5 to 20 weight percent, preferably about 5 to weight percent, in the composition The sodium silicate is generally added in the form of an aqueous solution, preferably having an Na 2 O:Si O 2 ratio of about 1:2 to 1:2 8.

Detergent active material useful herein must be stable in the presence of chlorine bleach, especially hypochlorite bleach, and those of the organic anionic, amine oxide, phosphine oxide, sulphoxide or betaine water dispersible surfactant types are preferred, the first mentioned anionics being most preferred They are used in amounts ranging from about 0 1 to 5 %, preferably about 0 3 to 2 0 % Particularly preferred surfactants herein are the linear or branched alkali metal mono and/or di-(C 8 _ 14) alkyl diphenyl oxide mono and/or disulphates or disulphonates, commercially available for example as DOWFAX (Registered Trademark) 3 B-2 and DOWFAX 2 A-1 In addition, the surfactant should be compatible with the other ingredients of the composition Other suitable surfactants include the primary alkylsulphates, alkylsulphonates, alkylaryl- sulphonates and sec -alkylsulphates Examples include sodium C 10-C 18 alkylsulphates such as sodium dodecyl- sulphate and sodium tallow alcoholsulphate; sodium C 10- C 18 alkanesulphonates such as sodium hexadecyl-1- sulphonate and sodium C 12-C 18 alkylbenzenesulphonates 15such as sodium dodecylbenzenesulphonates The corresponding potassium salts may also be employed.

As other suitable surfactants or detergents, the amine oxide surfactants are typically of the structure R 2 R 1 N-O, in which each R represents a lower alkyl group, for instance, methyl, and R 1 represents a long chain alkyl group having from 8 to 22 carbon atoms, for instance a lauryl, myristyl, palmityl or cetyl group.

Instead of an amine oxide, a corresponding surfactant phosphine oxide R 2 R 1 PO or sulphoxide RR 1 SO can be employed Betaine surfactants are typically of the structure R 2 R N R'COO-, in which each R represents a lower alkylene group having from 1 to 5 carbon atoms.

Specific examples of these surfactants are lauryl- dimethylamine oxide, myristyldimethylamine oxide, the corresponding phosphine oxides and sulphoxides, and the corresponding betaines, including dodecyldimethylammor- ium acetate, tetradecyldiethylammonium pentanoate, hexadecyldimethylammonium hexanoate and the like For biodegradability, the alkyl groups in these surfactants should be linear, and such compounds are preferred.

Surfactants of the foregoing type, all well known in the art, are described, for example, in U S Patents 3,985,668 and 4,271,030.

Thixotropic thickeners, i e thickeners or suspending agents which provide an aqueous medium with thixotropic properties, are known in the art and may be organic or inorganic water soluble, water dispersible or colloid-forming, and monomeric or polymeric, and should of course be stable in these compositions, e g.

stable to high alkalinity and chlorine bleach compounds, such as sodium hypochlorite Those especially preferred generally comprise the inorganic, colloid-forming clays of smectite and/or attapulgite types These materials are generally used in amounts of about 1 5 to 10, preferably 2 to 5 weight percent, to confer the desired thixotropic properties and Bingham plastic character in the assignee's prior disclosed LADD formulations of the aforementioned GB 2,116,199 A and GB 2,140,450 A It is one of the advantages of the LADD formulations of the present invention that the desired thixotropic properties and Bingham plastic character can be obtained in the presence of the potassium polyphosphates and the metal salt fatty acid stabilizers of the present invention with lesser amounts of the thixotropic thickeners For example, amounts of the inorganic colloid-forming clays of the smectite and/or attapulgite types in the range of from about 0 1 to 0 5 %, preferably 0 2 to 0 4 %, especially 0.25 t 0 30 %, are generally sufficient to achieve the desired thixotropic properties and Bingham plastic character when used in combination with the potassium polyphosphates and fatty acid metal salts physical stabilizers.

Smectite clays include montmorillonite (bento- nite), hectorite, attapulgite, smectite, saponite, and the like Montmorillonite clays are preferred and are -available under tradenames such as Thixogel (Registered Trademark) No 1 and Gelwhite (Registered Trademark) GP, H, etc, from Georgia Kaolin Company; and ECCAGUM (Registered Trademark) GP, H, etc, from Luthern Clay Products Attapulgite clays include the materials commercially available under the tradename Attagel (Registered Trademark), i e Attagel 40, Attagel 50 and Attagel 150 from Engelhard Minerals and Chemicals Corporation Mixtures of smectite and attapulgite types in weight ratios of 4:1 to 1:5 are also useful herein Thickening or suspending agents of the fore- going types are well known in the art, being described, for example, in U S Patent No 3,985,668 referred to above Abrasives or polishing agents should be avoided in the LADD compositions as they may mar the surface of fine dishware, crystal and the like.

The amount of water contained in these composi- tions should, of course, be neither so high as to produce unduly low viscosity and fluidity, nor so low as to produce unduly high viscosity and low flow- ability, thixotropic properties in either case being diminished or destroyed Such amount is readily deter- mined by routine experimentation in any particular instance, generally ranging from about 30 to 75 weight percent, preferably about 30 to 65 weight percent The water should also be preferably deionized or softened.

So far, the description of the LADD product, except as otherwise noted, conforms to the compositions as disclosed in the aforementioned U K Patent Applica- tions GB 2,116,199 A and GB 2,140,450, which are assigned to the applicants.

The LADD products of the U K Patent Applications GB 2,116,199 A and GB 2,140,450 exhibit improved rheo- logical properties as evaluated by testing product viscosity as a function of shear rate The composi- tions exhibited higher viscosity at a low shear rate.

and lower viscosity at a high shear rate, the data indicating efficient fluidization and gellation well within the shear rate extant within the standard dish- washer machine In practical terms, this means improved pouring and processing characteristics as well as less leaking in the machine dispenser-cup, compared to prior liquid or gel ADD products For applied shear rates corresponding to 3 to 30 rpm, viscosities (Brookfield) correspondingly ranged from about 10,000 to-

30,000 cps to about 2,000 to 6,000 cps, as measured at room temperature by means of an LVT Brookfield visco- meter after 3 minutes using a No 4 spindle one day after making A shear rate of 7 4 sec-1 corresponds to a spindle rpm of about 3 An approximate ten-fold increase in shear rate produces about a 3 to 9-fold reduction -in viscosity With prior ADD gels, the corresponding reduction in viscosity was only about two-fold Moreover, with such compositions, the initial viscosity taken at about 3 rpm was only about 2,500 to 2,700 cps The compositions of the applicants prior invention thus exhibit threshold fluidizations at- lower shear rates and of significantly greater extent in terms of incremental increases in shear rate versus incremental decrease in viscosity This property of the LADD products of the prior invention is summarized in terms of a thixotropic index (TI) which is the ratio of the apparent viscosity at 3 rpm and at 30 rpm, as measured at room temperature by means of an LVT Brook- field viscometer after 3 minutes using a No 4 spindle one day after making The prior compositions have a TI of from 2 to 10 The LADD compositions tested exhibited substantial and quick return to prior quiescent state consistency when the shear force was discontinued.

The present invention is based upon the discovery that the physical stability, i e resistance to phase separation, settling, etc, of the U K Patent Appli- cations GB 2,116,199 A and GB 2,140,450 and of the U S.

Patent Application Serial No 744,754 liquid aqueous ADD compositins can be significantly improved or not adversely affected while at the same time significantly improving the stability against variations in rheologi- cal properties with time and temperature by adding to the composition a small but effective amount of potassium polyphosphates and small effective amounts of a metal salt of a long chain fatty acid.

As an example of the improvement in Theological properties, it has been found that the viscosities at low shear rates, e g at a spindle rpm of about 3, apparent viscosities may often be increased from two- to three-fold with the incorporation of as little as 1 to 2 % or less of the potassium polyphosphates and as little as 0 25 % to 0 50 % of the fatty acid metal salt stabilizer At the same time, the physical stability may be improved to such an extent that even after twelve weeks or longer, over temperature ranges extending from near freezing to 400 C, the compositions containing the potassium polyphosphates and the metal salt stabilizers are of increased stability against variations in rheological properties with time and temperature and do not undergo any visible phase separation.

The potassium polyphosphate that can be used are generally commercially available Specific examples of potassium polyphosphates are potassium tripolyphosphate (TPP), potassium pyrophosphate and potassium hexametaphosphate The potassium tripolyphosphate (TPP) is preferred.

The amount of the potassium polyphosphates needed to achieve the desired enhancement of physical stability will depend-on such factors as the nature of the fatty acid salt, the nature and amountof the thixo- tropic agent, detergent active compound, inorganic salts, sodium TPP, other LADD ingredients, as well as the anticipated storage and shipping conditions. The amounts of the potassium polyphosphates stabilizing agents ( 50 % AI)

that can be used are in the range of from about 0 5 to 3 0 %, preferably from about 0.80 to 2 0 %, especially preferably about 1 0-1 8 %.

The preferred long chain fatty acids are the higher aliphatic fatty acids having from about 8 to about 22 carbon atoms, more preferably from about 10 to 20 carbon atoms, and especially preferably from about 12 to 18 carbon atoms, inclusive of the carbon atom of the carboxyl group of the fatty acid The aliphatic radical may be saturated or unsaturated and may be straight or branched Straight chain saturated fatty acids are preferred Mixtures of fatty acids may be used, such as those derived from natural sources, such as tallow fatty acid, coco fatty acid, soya fatty acid, etc, or from synthetic sources available from industrial manufacturing processes.

Thus, examples of the fatty acids from which the polyvalent metal salt stabilizers can be formed include, for example, decanoic acid, dodecanoic acid, palmitic acid, myristic acid, stearic acid, oleic acid, eicosanoic acid, tallow fatty acid, coco fatty acid, soya fatty acid, mixtures of these acids Stearic acid and mixed fatty acids are preferred.

The preferred metals are the polyvalent metals of Groups IIA, IIB and IIIB, such as magnesium, calcium, aluminium and zinc, although other polyvalent metals including those of Groups IIIA, IVA, VA, VIA, VIIA, IB, IVB, VB, VIB, VIIB, and VIII of the Periodic Table of the Elements can also be used Specific examples of such other polyvalent metals include Ti, Zr, V, Nb, Mn, Fe, Co, Ni, Cd, Sn, Sb and Bi Generally, the metals may be present in the divalent to pentavalent state.

Preferably, the metal salts are used in their higher oxidation states Naturally for LADD compositions, as well as any other applications where the composition of the present invention will or may not come into contact with articles used for the handling, storage or serving of food products or which otherwise may come into contact with or be consumed by people or animals, the metal salt should be selected by taking into consider- ation the toxicity of the metal For this purpose, the calcium and magnesium salts are especially highly preferred as generally safe food additives.

Many of these metal salts are commercially avail- able For example, the aluminium salts are available in the triacid form, e g aluminium steorate as aluminium tristearate, Al(C 17 H 35 COO))3 The monoacid salts, e g aluminium monostearate, Al(OH)2 (C 17 H 35 COO) and diacid salts, e g aluminium distearate, Al(OH)(C 17 H 35 COO)2, and mixtures of two or three of the mono-, di and triacid salts can be used for those metals, e g Al, with valences of + 3, and mixtures of the mono and diacid salts can be used for those metals, e g Zn, with valences of + 2 It is most preferred that the diacids of the + 2 valent metals and the triacids of the + 3 valent metals, the tetraacids of the + 4 metals, and the pentaacids of the + 5 valent metals, be used in predominant amounts For example, at least 30 %, preferably at least 50 %, especially preferably from 80 to 100 % of the total metal salt should be in the highest possible oxidation state, i e.

each of the possible valence sites is occupied by a fatty acid residue.

The metal salts, as mentioned above, are generally commercially available but can be easily produced by, for example, saponification of a fatty acid, e g.

animal fat, stearic acid, etc, or the corresponding fatty acid ester, followed by treatment with an hydroxide or oxide of the polyvalent metal, for example, in the case of the aluminium salt, with alum or alumina.

Calcium stearate, i e calcium distearate, magnesium stearate, i e magnesium distearate, alumin- ium stearate, i e aluminium tristearate, and zinc stearate, i e zinc distearate, are the preferred poly- valent fatty acid salt stabilizers Mixed fatty acid metal salts, such as the naturally occurring acids, e g coco acid, as well as mixed fatty acids resulting from the commercial manufacturing process are also advantageously used as an inexpensive but effective source of the long chain fatty acid.

The amount of the potassium polyphosphates and fatty acid salt stabilizers to achieve the desired enhancement of physical stability will also depend on such factors as the nature of the fatty acid salt, the nature and amount of the thixotropic agent, detergent active compound, inorganic salts, Na TPP, other LADD ingredients, as well as the anticipated storage and shipping conditions.

Generally, however, amounts of the polyvalent metal fatty acid salt stabilizing agents in the range of from about 0 10 to 0 5 %, preferably from about 0 2 to 0 4 %, especially preferably from about 0 25 to 0.30 % The use of the potassium polyphosphates with the polyvalent metal fatty acid salt stabilizing agents provide the long term physical stability, stability against variations in rheological properties with time and temperature and absence of phase separation upon standing or during transport at both low and elevated temperatures as are required for a commercially acceptable product.

In another embodiment of the invention fatty acids themselves can be used as stabilizers in place of the above described fatty acid metal salts.

For example, long chain fatty acids that can be used are the higher aliphatic fatty acids having from about 8 to about 22 carbon atoms, preferably from about to 20 carbon atoms, and more preferably from about 12 to 18 carbon atoms, inclusive of the carbon atom of the carboxyl group of the fatty acid The aliphatic radical may be saturated or unsaturated and may be straight or branched Straight chain saturated fatty acids are preferred Mixtures of fatty acids may be used, such as those derived from natural sources, such as tallow fatty acid, coco fatty acid, soya fatty acid, etc, or from synthetic sources available from industrial manufacturing processes.

Thus, examples of the fatty acids which can be used as stabilizers include, for example, decanoic acid, dodecanoic acid, palmitic acid, myristic acid, stearic acid, behenic acid, oleic acid, eicosanoic acid, tallow fatty acid, coco fatty acid, soya fatty- acid, and mixtures of these acids Behenic acid, stearic acid and mixed fatty acids can be used.

Many of the fatty acids are commercially available For example, stearic acid and behenic acid are readily available Mixed fatty acids, such as the naturally occurring acids, e g coco acid, as well as mixed fatty acids resulting from the commercial manu- facturing process are also advantageously used as an inexpensive -but effective source of long chain fatty- acids The sodium and potassium salts of the fatty acids can also be used as stabilizers.

The amount of the fatty acid stabilizers, and/or the sodium or potassium salts thereof that can be used are in the same range as the above mentioned fatty acid metal salts.

From the examples to be given below, it will be seen that, depending on the amounts, proportions and types of physical stabilizers and thixotropic agents, the addition of the potassium polyphosphates and of the fatty acid salt not only increases physical stability but also in some cases provides a simultaneous increase in apparent viscosity and provides stability against variations in rheological properties with time and/or temperature.

The physical stabilizing agents are added just before adding the clay thickener Excluding the chlorine bleach compound, total salt concentration (Na TPP, sodium silicate and carbonate) is generally about 20 to 50 weight percent, preferably about 30 to 40 weight percent in the composition.

A preferred method for mixing the ingredients of the LADD formulations involves first forming a mixture of the water, foam suppresor, detergent, physical stabilizers (potassium tripolyphosphate and fatty acid salt) and thixotropic agent, e g clay These ingredients are mixed together under high shear condi- tions, preferably starting at room temperature, to form a uniform dispersion To this premixed portion, the remaining ingredients are introduced under low shear mixing conditions For instance, the required amount of the premix is introduced into a low shear mixer and thereafter the remaining ingredients are added, with mixing, either sequentially or simultaneously Prefer- ably, the ingredients are added sequentially, although it is not necessary to complete the addition of all of one ingredient before beginning to add the next ingredient Furthermore, one or more of the ingredients can be divided into portions and added at different times Good results have been obtained by adding the remaining ingredients in the following sequence: sodium hydroxide, alkali metal carbonate, sodium silicate, sodium tripolyphosphate (hydrated), sodium tripolyphosphate (anhydrous or up to 5 % water), bleach (preferably, sodium hypochlorite) and sodium hydroxide.

Other conventional ingredients may be included in these compositions in small amounts, generally less than about 3 weight percent, such as perfume; hydro- tropic agents such as the sodium benzene, toluene, xylene or cumene sulphonates; preservatives; dyestuffs and pigments and the like, all of course being stable to chlorine bleach compound and high alkalinity (properties of all the components) Especially preferred for colouring are the chlorinated phthalo- cyanines and polysulphides of aluminosilicate which provide, respectively, pleasing green and blue tints.

Ti O 2 may be employed for whitening or neutralizing off- shades.

The liquid ADD compositions of this invention are readily employed in known manner for washing dishes, other kitchen utensils and the like in an automatic dishwasher, provided with a suitable detergent dispenser, in an aqueous wash bath containing an effective amount of the composition.

While the invention has been particularly described in connection with its application to liquid automatic dishwasher detergents it will -be readily understood by one of ordinary skill in the art that the benefits which are obtained by the addition of the potassium tripolyphosphate and the long chain fatty acid metal salt, namely increased physical stability of the clay based thixotropic suspension and stability against variation in rheological properties-with time, will apply equally well to other clay based thixotropic suspensions, such as the scouring paste formulations described in the aforementioned U S Patent 3,985,668.

The invention may be put into practice in various ways and a number of specific embodiments will be described to illustrate the invention with reference t D the accompanying examples.

All amounts and proportions referred to herein are by weight of the composition unless otherwise indicated.

EXAMPLES 1 to 7 In order to demonstrate the effect of the potassium tripolyphosphate and the metal salt stabili- zers, a number of liquid ADD formulations are prepared with varying amounts of the potassium tripolyphosphate and the fatty acid salt stabilizers and thixotropic clay thickener A base formulation having a composi- tion in the ranges specified in Table 1 below is made up, the specific proportions being given in Table 3.

TABLE 1

Percent Deionized water (adjusted to 100 %) 33 06 to 42 55 Monostearyl phosphate 0 16 Dowfax 3 B 2 ( 45 % Na monodecyl/didecyl 0 8 diphenyl oxide disulphonate - aqueous solution) Potassium TPP ( 50 % AI) O 1 6 Aluminium stearate 0 0 4 Pharmagel H 0 25 2 0 These products are mixed under high shear at room temperature and the following ingredients in the ranges given in Table 2 below are then added at room temperature, the specific proportions being given in Table 3.

TABLE 2

Percent Caustic soda solution ( 50 % Na OH) 2 2 to 10 2 Sodium carbonate, anhydrous 5 00 Sodium silicate 47 5 % solution of 15 74- Na 2 O:Si O 2 ratio of 1:2 4 Sodium TPP Hexahydrate (Thermphos N 12 00 hexa) Sodium TPP (substantially anhydrous, 12 00 i.e 0 5 %, especially 3 %, moisture) (Thermphos NW) Sodium hypochlorite solution ( 11 % 9 00 available chlorine) Liquid ADD formulations of Examples 1 to 7 as set out in Table 3 are prepared and are measured for density and apparent viscosity at 3 and 30 rpm (Table 3 A) and physical stability (phase separation) on standing and in a shipping test (Table 3 B) The results obtained are shown in the following Tables 3 A and 3 B. From the data reported in Tables 3 A and 3 B the following conclusions are reached:

The incorporation of 0 1 % aluminium stearate in a 1.25 % Pharmagel H containing formula, Example 2 (control) leads to an increase of the physical stability without altering the apparent viscosity as compared to Example 1 (control).

The incorporation of 0 4 % aluminium stearate in a 0.25 % Pharmagel H containing formula, Example 3 (control), as compared to Examples 1 (control) and 3 (control) leads to an increase of the physical stability and of the apparent viscosity The use of the higher aluminium stearate level of 0 4 %, Example 3 (control), also allows the reduction of the clay level content downward from 1 25 %, Example 2 (control) to 0.25 %, Example 3 (control), while maintaining the physical stability of the formulation.

The data in Table 3 also show that the simultan- eous use of about 1 6 % of potassium TPP in a 0 5 % or 0.3 % PHARMAGEL H containing formula, Examples 4 and 6, does not adversely affect the physical stability of the formulations while allowing the reduction in variation of rheological properties over time.

TABLE 3 A

EXAMPLE FORMULATION BROOK LVT DENSITY VISCOSITY (q/cm L) (KCPS)( 1) 3 30 RPM RPM 1 (con- trol) H 20 KTPP ( 50 %AI) Caustic Soda ( 50 %AI) Aluminium Stearate Pharmagel H 2 (con- trol) H 20 KTPP ( 50 %AI) Caustic Soda ( 50 %AI) Aluminium Stearate Pharmagel H = 41 75 % = O % = 2.2 % = 0.1 % = 1.25 % - 1 32 3 (con- trol) H 20 KTPP ( 50 %AI) Caustic Soda ( 50 %AI) Aluminium Stearate Pharmagel H = 42 45 % = 0 % = 2.2 % = 0.4 % = 0.25 % 4 H 20 = 40 60 % KTPP ( 50 %AI) = 1 6 % Caustic Soda ( 50 %AI) = 2 2 % Aluminium Stearate = 0 4 % Pharmagel H = 0 5 % 1.35 10 1.33 38 6 9 = 41 10 % = O %.

= 2.2 % = 0 % = 2 % 1 25 13 4 28 6 8 2.9 I TABLE 3 A (continued) EXAMPLE FORMULATION (con- trol) H 20 KTPP ( 50 %AI) Caustic Soda ( 50 %AI) Aluminium Stearate Pharmagel H BROOK LVT DENSITY VISCOSITY (g/cma) (KCPS)( 1) 3 30 RPM RPM = 38 5 % = 0 % = 6.2 % = 0.3 % = 0.3 % 1.36 3.9 H 20 KTPP ( 50 %AI) Caustic Soda ( 50 %AI) Aluminium Stearate Pharmagel H H 20 KTPP ( 50 %AI) Caustic Soda ( 50 %AI) Aluminium Stearate Pharmagel H = 37 06 % = 1.6 % = 6.2 % = 0.3 % = 0.3 % = 33 06 % = 1.6 % = 10 2 % = 0.3 % = 0.3 % 1.36 1.39 8 3 8 4 1 Note on Table 3 A ( 1) Measured with spindle 4 after 3 minutes on 24 hour old samples.

EXAM- PLE TABLE 3 B

UNSHAKEN LIQUID SEPARATION (%) (AFTER 12 WEEKS) GLASS BOTTLE PLASTIC BOTTLE 4 C RT 35 C 43 C 40 C RT 35 C 43 C ( 2) ( 2) ( 2) ( 2) ( 3) ( 3) ( 3) ( 3) 1-3 1-2 0 0 1-5 (con- trol 2 (con- trol) 3 (con- trol) 0 O O 0 O 4 O 0 0 0 O O _ O O O 0 0 0 0 (con- trol) 6 0 0 0 0 7 O 0 0 0 O O O O 0 O O O O O SHIP- PING TEST (%) ( 4) 1-5 Notes on Table 3 B ( 2) In Height (RT = room temperature = 20 + 20 C).

( 3) In Weight (RT = room temperature = 20 + 20 C).

( 4) Liquid separation measured after 6 weeks and 2000 Kms in a private car (in weight in a plastic bottle).

In order to determine the variations in rheologi- cal properties with time the apparent viscosities of the Examples 2 to 7 were measured at 3 RPM and 30 RPM after 1 day, 2 weeks, 4 weeks, 6 weeks and 12 weeks and the data obtained is reported in the Table 4 below.

The Table 4 data show that the addition of 1 6 % KTPP (Runs 4, 6 and 7) leads to a strong stabilization of the Theological properties variations with time without altering the physical stabilities of the formu- lations at a Pharmagel H clay content of 0 3 % and 0 5 %, as compared to the Examples 3 (control) and 5 (control) which show significant apparent viscosity variations with time.

Thus a comparison of Examples 5 and 6 which differ only in the presence or absence of KTPP show that in the presence of KTPP the viscosity at 30 rpm does not rise above 40 and even after 6 or 12 weeks standing the thixotropy ratio (thixotropy index measured at different times from making) has not risen to a value greater than 7 5 In the absence of KTPP the viscosity is 70 after 12 weeks and the thixotropy ratio is 12 after 6 weeks and 11 after 12 weeks.

A comparison of Examples 3 and 4 which differ in the presence or absence of KTPP and also differ in that Example 4 which contains KTPP also has twice the amount of Pharmagel reveals that although the viscosity at 30 rpm rises with time the thixotropy ratio values change much less than for Example 3 rising from 5 5 at 1 day to only 7 7 after 12 weeks whilst the thixotropy ratio of Example 3 rises from 3 4 to 8 0 and then drops and then rises again to 10 after 12 weeks.

TABLE 4

SIMULTANEOUS USE OF POTASSIUM TPP AND ALUMINIUM TRISTEARATE BROOKFIELD LVT VISCOSITY AT 3 AND 30 RPM AFTER

INDICATED PERIOD AT RT (KCPS) ( 1) EXAMPLE 1 DAY T 1 ( 3)2 WEEKS TR( 4) 4 WEEKS TR 2 28/6 8 ( 4 1) 24/3 4 ( 7 1) 34/8 9 ( 3 8) (con trol) 10/2 9 ( 3 4) 38/6 9 ( 5 5) 51/6 4 ( 8 0) ( 2) 56/8 ( 7) 70/9 8 ( 7 1) ( 5.1) 21/3 0 ( 7) 8/3 8 ( 2 1) 30/4 46/5 1 ( 9) ( 7.5) 26/5 0 ( 5 2) 20/4 1 ( 4 9) 35/10 1 ( 3 5) 20/5 0 ( 4) 3 (con- trol) 20/3 9 (con- trol) TABLE 4 (Cont'd) SIMULTANEOUS USE OF POTASSIUM TPP AND ALUMINIUM TRISTEARATE BROOKFIELD LVT VISCOSITY AT 3 AND 30 RPM AFTER

INDICATED EXAMPLE

2 (control) PERIO AT RT (KCPS) 6 WEEKS TR 53/7 ( 7 6) ( 1) 12 WEEKS 41/6 7 TR ( 6.1) 3 (control) 48/7 6 ( 6 3) 91/12 (control) ( 7.6) 61/5 1 ( 12) 30/5 1 ( 5 9) 25/6 Notes on Table 4 ( 1) Measured with spindle 4 after bottle left on a shelf.

3 minutes in a glass ( 2) No measurement.

( 3) TI = thixotropy index = viscosity at viscosity at 30 rpm after 1 day.

( 4) TR = ratio of thixotropy at 3 and (analogous to thixotropy index).

/20 100/13 70/6 3 ( 10) ( 7.7) ( 11) 38/5 4 ( 4.2) 36/10 ( 7) ( 3.6) rpm/ rpm EXAMPLE 8

The following gel-like thixotropic liquid ADD is prepared following the same general procedures as for Examples 1 to 7, the ingredients and proportions being given below in Table 5.

TABLE 5

Ingredient Sodium silicate ( 47 5 % solution of Na 2 O:Si O 2 ratio of 1:2 4) Monostearyl phosphate Dowfax 3 B-2 Thermphos NW Thermphos N hexa Potassium TPP ( 50 % AI) Aluminium stearate Sodium carbonate, anhydrous Caustic soda solution ( 50 % Na OH) Pharmagel H Sodium hypochlorite solution ( 11 %) Water Amount Wt% 7.48 0.16 0.36 12.0 12.0 1.6 0.25 4.9 6.2 1.25 1.0 balance p H = 13 to 13 4 Minor amounts of perfume, colour, etc can also be added to formulation.

The composition is found to have good thixotropic properties, good stability against phase separation and good rheological properties variations with time.

EXAMPLE 9

A gel-like thixotropic liquid ADD is prepared as in Example 8, with the change that 1 6 % ( 50 % AI) of potassium pyrophosphate is substituted for the potassium TPP Results similar to those of Example 8 are obtained.

EXAMPLE 10

The following gel-like thixotropic liquid ADD is prepared following the same general procedures as in Examples 1 to 7, the proportions and ingredients being as set out below in Table 6.

TABLE 6

Inqredient Sodium silicate ( 47 5 % solution of Na 2 O:Si O 2 ratio of 1:2 4) Amount Wt% 7.48 Monostearyl phosphate 0 16 Dowfax 3 B-2 0 36 Thermphos NW 12 O Thermphos N hexa 12 0 Potassium TPP ( 50 %AI) 1 6 Stearic Acid 0 4 Sodium carbonate, anhydrous 5 0 Caustic soda solution ( 50 % Na OH) 3 1 Pharmagel H 0 5 Sodium hypochlorite solution ( 11 %) 1 O Water Balance Minor-amounts of perfume, colour, etc, can also be added to formulation.

EXAMPLE 11

The following gel-like thixotropic liquid ADD is prepared following the same general procedures as in Examples 1 to 7, the proportions and ingredients being as set out in Table 7 below.

TABLE 7

Ingredient Sodium silicate ( 47 5 % solution of Na 2 O:Si O 2 ratio of 1:2 4) Amount Wt% 7.48 Monostearyl phosphate 0 16 Dowfax 3 B-2 0 36 Thermphos NW 12 0 Thermphos N hexa 12 0 Potassium TPP ( 50 %AI) 1 6 Behenic Acid 0 2 Sodium carbonate, anhydrous 5 0 Caustic soda solution ( 50 % Na OH) 6 2 Pharmagel H 0 5 Sodium hypochlorite solution ( 11 %) 1 0 Water Balance Minor amounts of perfume, colour, etc, can also be added to formulation.

It is understood that the foregoing detailed description is given merely by way of illustration and that variations may be made therein without departing from the spirit of the invention.

Claims (26)

1 An aqueous thixotropic liquid composition comprising a clay thixotropic agent, potassium polyphosphate and at least one long chain fatty acid or a metal salt of a long chain fatty acid, the said potassium poly- phosphate and the said fatty acid or fatty acid metal salt being in an amount effective to increase the physical stability and the stability to variations in Theological properties variations with time of the composition, water, and at least one additional ingredient selected from the group consisting of organic deter- gents, p H modifying agents, chlorine bleach, detergent, builder, sequestering agent, foam inhibitors, abrasive particles and mixtures thereof.

2 A composition as claimed in Claim 1 in which the said composition comprises at least one of potassium tripolyphosphate, potassium pyrophosphate and potassium hexametaphosphate.

3 A composition as claimed in Claim 1 in which the said composition comprises potassium tripolyphos- phate.

4 A composition as claimed in Claim 1, 2 or 3 in which the metal salt comprises a polyvalent metal salt of a metal of Group II, III or IV of the Periodic Table of the Elements of a long chain fatty acid having from about 8 to 22 carbon atoms or mixture of two or more of such fatty acids.

A composition as claimed in any one of Claims 1 to 4 in which the polyvalent metal is aluminium, zinc, calcium or magnesium.

6 A composition as claimed in any one of Claims 1 to 4 in which the fatty acid metal salt is aluminium stearate, calcium stearate or magnesium stearate.

7 An aqueous thixotropic automatic dishwasher composition comprising approximately by weight:

(a) 5 to 35 % sodium tripolyphosphate; (b) 2 5 to 20 % sodium silicate; (c) 0 to 9 % alkali metal carbonate; (d) 0 1 to 5 % chlorine bleach stable, water- dispersible organic detergent active material; (e) 0 to 5 % chlorine bleach stable foam depressant; (f) chlorine bleach compound in an amount to provide about 0 2 to 4 % of available chlorine; (g) thixotropic thickener in an amount sufficient to provide the composition with a thixotropy index of about 2 to 10; (h) 0 to 8 % of sodium hydroxide; (i) a physical and rheological properties stabilizing agent comprising at least one of potassium tripolyphosphate, potassium pyrophosphate and potassium hexametaphosphate and a polyvalent metal salt of a long chain fatty acid; and (j) balance water.

8 An aqueous thixotropic automatic dishwasher composition comprising approximately by weight:

(a) 5 to 35 % tripolyphosphate; (b) 2 5 to 20 % sodium silicate;- (c) 0 to 9 % alkali metal carbonate; (d) 0 1 to 5 % chlorine bleach stable, waterdispersible organic detergent active material; (e) 0 to 5 % chlorine bleach stable foam depressant; (f) chlorine bleach compound in an amount to provide about 0 2 to 4 % of available chlorine; (g) thixotropic thickener in an amount sufficient to provide the composition with a thixotropy index of about 2 to 10; (h) 0 to 8 % of sodium hydroxide; (i) 0 5 to 3 0 % potassium polyphosphate and 0 1 to 0 5 % of at least one long chain fatty acid or a metal salt of a long chain fatty acid; (j) balance water.

9 A composition as claimed in Claim 7 or Claim 8 in which the stabilizer comprises potassium tripoly- phosphate.

10 A composition as claimed in Claim 7 or Claim 8 in which the stabilizer comprises potassium pyrophos- phate.

11 A composition as claimed in Claim 7 or Claim 8 in which the stabilizer comprises potassium hexameta- phosphate.

12 A composition as claimed in any one of Claims 7 to 11 in which the metal salt stabilizer is a poly- valent metal salt of an aliphatic fatty acid having from about 8 to 22 carbon atoms.

13 A composition as claimed in any one of Claims 7 to 12 in which the acid has from about 12 to 18 carbon atoms.

14 A composition as claimed in any one of Claims 7 to 13 in which the metal salt stabilizer is the aluminium salt or zinc salt of the said fatty acid.

A composition as claimed in any one of Claims 7 to 14 in which the metal salt stabilizer is aluminium stearate.

16 A composition as claimed in any one of Claims 7 to 14 in which the-metal salt stabilizer is zinc stearate.

17 A composition as claimed in any one of Claims 1 to 16 which contains 0 1 to 0 5 weight percent clay.

18 A composition as claimed in Claim 18 which contains 0 2 to 0 4 % by weight clay.

19 A composition as claimed in anyone of claims 1 to 18 which contains 0 5 to 3 0 weight percent potassium polyphosphate.

A composition as claimed in Claim 19 which contains 0 8 to

2 0 % by weight of the potassium polyphosphate.

21 A composition as claimed in any one of Claims 1 to 20 which contains 0 1 to 0 5 weight percent fatty acid metal salt.

22 A composition as claimed in Claim 21 which contains 0 2 to 0 4 % by weight fatty acid or fatty acid metal salt.

23 A composition as claimed in any one of Claims 1 to 22 in which the thixotropic thickener (g) is an inorganic, colloid-forming clay.

24 An aqueous thixotropic automatic dishwasher composition as claimed in any one of Claims 1 to 23 in which ingredient (i) comprises potassium polyphosphate and a polyvalent metal salt of an aliphatic fatty acid having from 12 to 18 carbon atoms.

A composition as claimed in Claim 1 substan- tially as specifically described herein with reference to the accompanying Examples 4, 6, 7, 10, 11, 12, or 13.

26 A method for cleaning soiled dishware in an automatic dishwashing machine which comprises contacting the soiled dishware in an automatic dish- washing machine in an aqueous washbath having dispersed therein an effective amount of a composition as claimed in any one of Claims 1 to 25.

Published 1988 at The Patent Office State House, 6671 High Holborn, London WCIR 4 TP Further cop Ies may be obt ained from The Patent Offce.

Sales Branch, St Mary Cray, Orpington, Kent BR 5 3RD Printed by Multiplex techniques ltd St Mary Cray, Kent Con 1/87.