AU608047B2 - Thixotropic clay aqueous suspensions containing polycarboxylic acids and metal salts thereof stabilizers - Google Patents

Description

COMMONWEALTH OF AUSTRALITRA 4 7 Patents Act 1952 C O MP L E T E S P E. C I.F. I-_CI-A T I O N

(ORIGINAL)

Application Number Lodged This document contains the Complete Specification Lodged amendments made undcr Accepted Section d9 ai' is correct for !l printing.

Published 0 1 Priority 21 August 1987 Related Art So Name of Applicant COLGATE-PALMOLIVE COMPANY 00 S Address of Applicant 300 Park Avenue, New York a~ New York 10022, United States of America Actual Inventor/s o Nagaraj S. Dixit Address for Service F.B. RICE CO., Patent Attorneys, aoo 28A Montague Street, Sso Balmain N.S.W. 2041 Complete Specification for the invention entitled: Thixotropic clay aqueous suspensions containing polycarboxylic acids and metal salts thereof stabilizers The following statement is a full description of this invention including the best method of performing it known to us:-

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i'1 T- i ;ilappfean is related to appllietate aonigncc's eopegjjtj applications Serial No. 903,924 filed Septe 6 which is a continuation-in-part o e 44,754 filed June 14, 1985 and to Serial Hflni August 7, 1006.

4 5 The present invention relates to thixotropic clay aqueous suspension with improved physical stability. More specifically the invention relates to the use of polycarboxylic acids and metal salts thereof as physical stabilizers for thixotropic clay aqueous suspensions.

The present invention specifically relates to automatic dishwashing 10 detergent compositions having thixotropic properties, improved chemical 0000 and physical stability, and with increased apparent viscosity, and which Sare readily dispersible in the washing medium to provide effective cleaning S° of dishware, glassware, china and the like.

Commercially available household-machine dishwasher detergents o *ie 15 provided in powder form have several disadvantages, e.g. non-uniform S*o composition; costly operations necessary in their manufacture; tendency to Scake 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 dishwasher 20 machine dispenser.

Recent research and development activity has focused on the gel or automatic-dishwasher products characterized 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, and moreover yield spotty residues on dishware, glassware, china and the like. Ideally, thixotropic cleansing compositions should be ,iio; highly viscous in a quiescent state, Bingham plastic in nature, and have I-LIIILIILI~ ii 2 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.

The provision of automatic-dishwasher compositions in t 10 gel form having the aforedescribed properties, 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 sodium tripolyphosphate (NaTPP) to soften or tie up hard-water minerals and to emulsify and/or peptize soil; sodium silicate to supply the alkalinity necessary for effective detergency and to provide protection for fine china glaze and .u 20 pattern; sodium carbonate, generally considered to be S° optional, to enhance alkalinity; a chlorine-releasing agent to aid in the elimination of soil specks which lead 0 a to water spotting; and defoamer/surfactant to reduce 0 o foam, thereby enhancing machine efficiency and supplying S 25 requisite detergency. See, for a a 6 0 1-.

example, SDA Detergents in Depth, "Formulations 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 No. 41115,308 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 Cl-(hypochlorite) bleach but no organic surfactant or foam depressant. The product is described, moreover, as a detergent 000 slurry with no apparent thixotropic properties.

0000o0 U.S. Patent No. 3,985,668 describes abrasive scouring cleaners of gel-like consistency containing suspending agent, preferably the Smectite and attapulgite types of clay; abrasive, e.g. silica sand or 0 0" perlite; and filler comprising light density powdered polymers, 0 expanded perlite and the like, which has a bouyancy and thus stabilizing 20 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 o0 essential ingredients. Optional ingredients include hypochlorite bleach, bleach stable surfactant and buffer, e.g. silicates, carbonates, and monophosphates. Builders, such as NaTPP, 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) pH 10 levels is achieved by the buffer/builder components. High pH is said to minimize decomposition of chlorine bleach and undesired interaction between surfactant and bleach. Foam killer is not disclosed.

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ii U i I .0000 rr In U.K. Patent Application GD 2,116,199A and GB 2,140,450A, 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: 5 to 35% alkali metal tripolyphosphate; 2.5 to 20% sodium silicate; 0 to 9% alkali metal carbonate; 0.1 to 5% chlorine bleach stable, water dlis detergent active material; 0 to 5% chlorine bleach stable foam depresst chlorine bleach compound in an amount to pro 4% of available chlorine; thixotropic thickener in an amount sufficient to p.

composition with thixotropy index of about 2.5 to sodium hydroxide, as necessary, to adjust pH; and balance water.

ADD compositions so formulated are low-foaming; are readily soluble in the washing medium and most effective at pH values best conducive to improved cleaning performance, viz, pH 10.5-14. The compositions are normally of gel consistency, i.e. a highly viscous, opaque jelly-like material having Bingham plastic character and thus relatively high yield values. Accordingly, a definite shear force is necessary to initiate or increase flow, such as would obtain within the agitated dispenser cup of an energized automatic dishwasher. 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 -4- O0 0 0l 0 Oa a 6 OB o0 0 o a Q 0 viscosity, Bingham plastic state closely approximating its prior consistency.

U.S. Patent 4,511,487 dated April 16, 1985 describes a low-foaming detergent paste for dishwashers. The patented thixotropic cleaning agent has a viscosity of at least 30 Pa.s at 20 0 C as determined with a rotational viscometer at a spindle speed -of 5 revolutions per minute. The composition is based on a mixture of flpely 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 o ammonium salts, has also been described Mardis, JAOCS, Vol. 61, No. 2, p. 382 (1984)).

.,oI 15 While these previously disclosed liquid ADD formulations are not o I subject or are subject to a lesser degree to one or more of the above described deficiencies, it has been found that further improvements in oo 'physical stability at lower costs are desired to increase the shelf-life of the product and thereby enhance consumer acceptance.

While the combination of clay thickener and polyvalent metal fatty acid salt stabilizer disclosed in the above mentioned Serial No. 744,754 has been found to provide satisfactory long term stability, such as absence of phase separation for periods of up to 12 weeks and longer, it is desirable to "*pu further improve the stability so as to avoid phase separation for up to six months or more.

Further, the use of the known stabilizers, e.g. polyvalent metal fatty acid salt stabilizers and clay thickeners require a specified order of addition of the various ingredients and the close control of the process conditions during formulation of the compoqition is critical to obtain the desired thixotropic properties and low foam characteristics.

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

Accordingly, it is an objective of the invention to provide anti-settling additives for thixotropic clay aqueous suspensions.

It is another object of the invention to provide liquid ADD Scompositions having thixotropic properties with improved physical stability and rheological properties at lower costs by using polycarboxylic acids and metal salts thereof in place of the more expensive polyvalent metal salts of fatty acids.

It is still another object of the invention to provide thixotropic liquid ADD compositions having reduced levels of thixotropic thickener without adversely effecting the generally high viscosities at low shear rates and lower viscosities at high shear rates which are characteristic of the desired thixotropic properties.

More broadly, it is an object of this invention to improve the stability of aqueous thixotropic clay based compositions, especially liquid automatic diswasher detergent pastes or gels, by incorporating in the clay aqueous suspension a minor amount of a polycarboxylic acid and metal salt thereof 20 effective to increase the apparent viscosity of the formulation and to inhibit the settling of the suspended particles and to prevent phase separation.

S" Unlike the polyvalent metal long chain fatty acid salts the polycarboxylic acids and metal salts thereof of the present invention can be easily incorporated in the product, e.g. either by emulsifying them with the surfactants or by directly adding them to the batch. The process conditions for formulating the composition are not critical. The polyearboxylic acids and the metal salts thereof are easily dispersed in the composition. The addition of the polycarboxylic acids and metal salts thereof allows reduction of the amount of clay that would be required in the absence of the polycarboxylic acids and metal salts thereof. Further, j, _i i. ilu- i: I i~_ the rheological properties of the product can be fine tuned by adjusting the amount of the polycarboxylic acids and metal salts thereof added to the composition.

These and other objects of the invention which will become more readily understood from the following detailed description of the invention and preferred embodiments thereof are achieved by incorporating in a normally gel-like aqueous liquid composition p small but effective amount of a physical stabilizer which is polycarboxylic acids and metal salts thereof.

More particularly, according to a preferred and specific embodiment of the invention, there is provided a normally gel-like automatic dishwasher detergent composition in which is incorporated an amount of polycarboxylic acids and metal salt thereof which is effective to increase the apparent a viscosity of the formulation and to inhibit settling of the suspended aparticles, such as detergent builder and thixotropic clay agent.

S 15 In accordance with this particular aspect, the present invention provides a normally gel-like aqueous automatic dishwasher detergent composition having thixotropic properties which include, on a weight basis: o 4 e 5 to 35% alkali metal tripolyphosphate; 0 04 o 2.5 to 20% sodium silicate; S 20 0 to 9% alkali metal carbonate; 0.1 to 5% chlorine bleach stable, water dispersible organic detergent active material; 'o *I 0 to 5% chlorine bleach stable foam depressant; oo" chlorine bleach compound in an amount to provide about 0.2 to 4% of available chlorine; thixotropic thickener in an amount sufficient to provide the composition with thixotropy index of about 2.5 to 10; and 0 to 8% sodium hydroxide; polycarboxylic acids and metal salts thereof in an amount effective to increase apparent viscosity and the the physical stability of the composition; and -7balance 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 automnatic dishwashing machine and will, within just a few seconds, promptly thicken to its normal gel-like or pasty state to remain securely within the dispensing cup until shear forces are again applied thereto, such as by the water spray from the dishwashing machine.

*The present invention is based upon the surprising and unexpected discovery that the same or improved rheological properties and physical stability, i.e. resistance to phase separation, settling, etc., as in the 15 prior liquid aqueous ADD compositions can be achieved, at lower cost and 4 o without any particular processing requirements, by adding to the composition an effective stabilizing amount of polycarboxylic acids and metal salts thereof in place of the polyvalent metal fatty acid salt. At the same time, improvements in spotting and filming performance fewer ,o 20 spots and reduced filming) can be achieved. Amazingly, formulations prepared with, for example, 0.03 to 0.2% of the polycarboxylic acids and metal salts thereof have excellent rheological properties and have been stable in storage for up to six months.

"o Generally, LADD effectiveness is directly related to available chlorine levels; alkalinity; solubility in washing medium; and (d) foam inhibition. It is preferred herein that the pH of the LADD composition 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 pH level. Excess carbonate is to be avoided, however, since it may cause the formation of needle-like crystals of carbonate, thereby '1 impairing the stability, as well as impairing the dispensibility of the product from, for example, squeeze tube bottles. Caustic soda (NaOH) serves the further function of neutralizing the phosphoric or phosphonic acid ester foam depressant when present. About 0.5 to 6 wt% of NaOH and about 2 to 9 wt% of sodium carbonate in the LADD composition are typical, although it should be noted that sufficient alkalinity may be provided by the NaTPP and sodium silicate.

The NaTPP employed in the LADD composition in a range of about 8 to 35 wt%, preferably about 20 to 30 wt%, should preferably be. free of heavy metal which tends to decompose or inactivate the preferred sodium hypochlorite and other chlorine bleach compounds. The NaTPP 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 15 using a 0.5:1 to 2:1 weight ratio of anhydrous to hexahydrated NaTPP, 'o values of about 1:1 being particularly preferred.

Foam inhibition is important to increase dishwasher machine efficiency ao"o and minimize destabilizing effects which might occur due to the presence of o a a excess foam within the washer during use. Foam may be sufficiently S 20 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 o amachine whereby suitable adjustment of the proportions of NaTPP which has a water softening effect may aid in providing the desired degree of foam inhibition. However, there may optimally be included a chlorine bleach stable foam depressant or inhibitor where a low foam LADD is desired. Particularly effective are the alkyl phosphonic acid esters of the formula .0

II

HO- P R II OR Le 1 ;i i L, available for example from BASF-Wyandotte the alkyl acid phosphate esters of the formula 0

II

HO-P -OR

OR

PCUK-PAE), and especially a &o 0 0* 000 000000 do" a 0 00 O 0 0 0 0 0 00 00 a "a n' a 0o s o D a 0 00 0 0 0 6 00O 0T 09 00 0.

0& 00 0 00 0 0 0 available, for example, from Hooker (SAP) and Knapsack (LPKn-158), in which one or both R groups in each ,type of eater may represent independently a C 1 2 2 0 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 1 6 1 8 alkyl acid phosphate eaters such as monostearyl/distearyl acid phosphates 1.2/1 (Knapsack) or 4/1 (UGINE KULIIPLAN). When employed, proportions of 0.1 to 5 wt%, preferably about 0.1 to 0.5 wt%, of foam depressant in the composition is typical, the weight ratio of detergent active component 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 polycarboxylic acids and metal salts thereof act as foam killers.

Although any chlorine bleach compound may be employed in the compositions of this invention, such as dichloro-isocyanurate, ma ic s vc dichloro-dimethyl hydantoin, or chlorinated TSP,A alkali metal, e.g.

potassium, lithium, megneoin and especially sodium, hypochlorite is preferred. The composition should 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 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 ~~iu~~~nunu--ricw (NaOCI) solution of from about 11 to about 14% available chlorine in amounts of about 3 to 20%, preferably about 7 to 12% by weigl.:, 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 wt%, preferably about 5 to 15 wt%, in the composition. The sodium silicate is generally added in the form of an aqueous solution, preferably having an Na20:SiO 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 o°,i anionic, amine oxide, phosphine oxide, sulphoxide or betaine water dispersible surfactant types are preferred, the first mentioned anionics Sbeing most preferred. They are used in amounts ranging from about 0.1 o 15 to preferably about 0.3 to Particularly preferred surfactants a0 0 o °o herein are the linear or branched alkali metal mono- and/or di-(C8 1 4 alkyl diphenyl oxide mono and/or disulphates or disulfonates, commercially 0ono 0available for example as DOWFAX (Registered Trademark) 3B-2 and "o DOWFAX 2A-1. In addition, the surfactant should be compatible with the 20 other ingredients of the composition. Other suitable surfactants include 84 the primary alkylsulphates, alkylsulphonates, alkylaryl-sulphonates and sec.-alkylsulphatesa Examples include sodium C 1 0

-C

1 8 alkylsulphates such 4°B as sodium dodecylsulphate and sodium tallow alcoholsulphate; sodium .0 C10-C18 alkanesulphonates such as sodium hexadecyl1l-sulphonate and sodium C 12

-C

1 8 alkylbenzenesulphonates such 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 R2R 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 I-

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11 t 0 4 o o 0 t~0 0 0 o D lauryl, myristyl, palmityl or cetyl group. Instead of an amine oxide, a corresponding surfactant phosphine oxide R 2 R PO or sulphoxide RR SO can be employed. Betaine surfactants are typically of the structure R2R 1

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, myristyldirnetylamine oxide, the corresponding phosphine oxides and sulphoxides, and the corresponding betaines, including dodecyldimethylammonium 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.

Thikotropcl 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, weter dispersible or colloid-forming, and monomeric or polymeric, and should of course be stabie in these compositions, e.g. stable to high alkalinity and chlorine bleach compounds, such as sodium hypochlorite. Those especially preferred geneially comprise the inorganic, colloid-forming clays of smectite and/or attapulgite types. These materials were generally used in amounts of about 1.0 to 10, preferably 1.2 to 5 wt%, to confer the desired thixotropic properties and Bingham plastic character in the assignee's prior disclosed LADD formulations of the aforementioned GB 2,116,199A and GB 2,140,450A, It ia 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 polycarboxylic acids and metal salts thereof stabilizers 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 preferably 0.1 to especially 0.1 to are -12- 0 n0 0o 0 0 00 0 0o 0e i 0 40 0 Si ra 0 D 0~

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4 0 I<f *415 444440 b0 0440 4 #44040 15 4 s a i S6 t 1 S 4 0 generally sufficient to achieve the desired thixotropic properties and Bingham plastic character when used in combination with the physical stabilizer.

Smectite clays include montmorillonlte (bentonite), 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 foregoing 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 compositions 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 flowability, thixotropic properties in either case being diminished or destroyed. Suc. amount is readily determined by routine experimentation in any particular instance, generally ranging from about 30 to 75 wt%, preferably about 35 to 65 wt% and more preferably from about 35 to 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 Applications GB 2,116,199A and GB 2,140,450A, which are assigned to applicants' assignee.

The LADD products of the prior U.K. Patent AppIication GB 2,116,199A and GB 2,140,450 exhibit improved rheological properties as -13-

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evaluated by testing product viscosity as a function of shear rate. The compositions 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 rates extent within the standard dishwasher 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 prodpcts. For applied shear rates i corresponding to 3 to 30 rpm, viscosities (Brookfield) correspondingly ranged from about 10,000 to 30,000 cps to about 3,000 to 7,000 cps, as measured at room temperature by means of an LVT Brookfield viscometer H -1 j after 3 minutes using a No. 4 spindle. A shear rate of 7.4 sec corresponds to a spindle rpm of about 3. An approximate ten-fold Sincrease in shear rate produces about a 3- to 9-fold reduction in viscosity.

With prior ADD gels, the corresponding reduction in viscosity was only 15 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

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of the assignee's prior invention thus exhibit threshold fluidizations at 4 lower shear rates and of significantly greater extent in terms of I) incremental increases in shear rate versus incremental decrease in viscosity. This property of the LADD products of the prior invention is 1 S" summarized in terms of a thixotropic index (TI) which is the ratio of the apparent viscosity at 3 rpm and at 30 rpm. The prior compositions have a TI of from 2 to 10. The LADD compositions tested exhibited substantial 4 14 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 Applications GB 2,116,199A and GB 2,140,450 and-' U.S. Paten A.i -S.r id o. liquid aqueous ADD compositions can be significantly improved or not adversely affected while at the same time Ssignificantly increasing the apparent viscosity and improving the physical -14stability of the formulations and at lower cost, by adding to the composition a small but effective amount of polycarboxylic acids and metal salts thereof.

As an example of the improvement in rheological 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. 0.2% or less, e.g. 0.15%, of the polycarboxylic acids and metal salts thereof stabilizers. At the same time, the physical stability may be improved to such an extent that even after a long time, e.g. 6 months aging at 200C the compositions containing the polycarboxylic acids and metal salts thereof stabilizers do not undergo any visible phase separation.

Detailed Description of Stabilizing Agents The physical stabilizing agents that are used in accordance with the

S

a 15 present invention are the polycarboxylic acids and the metal salts thereof.

o s More particularly the stabilizers are low molecular weight carboxylic acids and the monovalent metal and polyvalent metal salts thereof.

1 Polycarboxylic Acids The polycarboxylic acids that can be used in accordance with the present invention are the dimers and trimers of fatty acids, preferably the 4 unsaturated fatty acids. The Cg to C 2 2 fatty acids can be used. The dimers and trimers are preferably prepared from the C12-C20 fatty acids 4 and more preferably from the C 1 6

-C

2 0 unsaturated fatty acids. The most preferred dimer and trimer acids are prepared from C18 unsaturated fatty acids, e.g. oleic acid and linoleic acid.

The monovalent metal salts and the polyvalent metal salts of the dimers and trimers of the fatty acids, preferably the unsaturated fatty acids, can also be used in the present invention. The ammonium salts of the dimers and trimers of the unsaturated fatty acids can also be used in the present invention.

A particular preferred group of polycarboxylic acids are the dimers and trimers of C 1 8 unsaturated fatty acids that are available from Emery Industries, Division of National Distillers Chemical Corp. These materials are available under the following trade names: Dimers Trimers Polybasic Acid Empol 1010 Empol 1040 Empol 1052 Empol 1018 Empol 1041 Empol 1022 SEmpol 1024 The Empol 1040 and Empol 1052 are of particular interest. The Empol 1040 Trimer Acid typically contains 80% polybasic acids, 18% dibasic acid i e and 2% 'monobasic acid. The Empol 1052 Polybasic Acid contains 63% tribasic, tetrabasic and higher acids with about 34% dibasic acid.

k ,o Q0 In addition to the dimer and trimer acids, the adepic and azelaic 4' 15 polycarboxylic acids and their mono metal and ammonium salts and polyvalent metal salts can also be used as stabilizing agents in the present invention.

Monovalent Metal And Ammonium Salts of Polycarboxylic Acids The monovalent metal salts that can be used are the Group IA metals 20 of the Periodic Table Of The Elements, and in particular the alkali metal salts. The Group IA monovalent metals that are included are Li, Na, K, ,4 Rb, Cs and Fr. The preferred monovalent alkali metals are Na and K.

There may also be used as an alkali metal the NH 4 ammonium cation.

4 The chlorine bleach compounds are, however, not to be used with the ammonium fatty acid salt stabilizers, since they are not compatible with chlorine bleach compounds. In the formulations in which the ammonium fatty acid stabilizers are used, the chlorine bleach can be omitted or an oxydizing enzyme can be substituted for the chlorine bleach.

The redox enzymes, also known as oxidoreductase enzymes, can be used in the present invention. These enzymes catalyze chemical reductions -16and oxidations and are involved in the chemical breakdown of foods remaining on the dishware and utensils that are to be cleaned. Suitable enzymes that can be used are glucose oxidase, catalase and lipoxidase enzymes.

There can also be used in the formulations of the present invention proteolytic and amylolytic enzymes and mixtures thereof. The proteolytic enzymes suitable for use include liquid, .powder or slurry enzyme preparations. Suitable liquid enzyme preparations include "Alcalase" and "Esperase" sold by Novo Industrie, Copenhagen, Denmark. Liquid protease and liquid amylase enzymes can be used. Suitable alpha-amylase liquid enzyme preparations are those sold by Novo Industries and 4 Gist-Brocades under the trade names "Termamyl" and "Maxamyl", Srespectively.

The enzymes can be used in amounts of about 0.5 to preferably e. 15 about 0.5 to 2.0% and more preferably about 0.5 to o'a, Polyvalent Metal Salts of Polycarboxylic Acids The preferred polyvalent metals are the polyvalent metals of Groups S IIA, IIB and IIIB, such as magnesium, calcium, aluminum and zinc, 4 44 although other polyvalent metals, including those of Groups IIIA, IVA, VA, VIA, VIIA, IB, IVB, VB, VIB, VIIB and VIII of the Periodic Table s 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, S 5 Bi, etc. 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 invention composition will or may 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 consideration the toxicity of the metal. For this purpose, the calcium and magnesium salts are especially highly preferred as generally safe food additives.

I(""l~---crrt~curr~- 1 i- LI Naturally, for LADD compositions, as well as any other applications where the invention composition will or may 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 use of the polycarboxylic acids and metal salts thereof as the stabilizing agent are of particular advantage because of their known low toxicity. For this purpose, the polycarboxylic acids per se, e.g. dimers and trimers of C 1 8 unsaturated fatty acid, the monovalent Na and K and the NH 4 salts and the polyvalent Ca and Mg metal salts thereof are 10 especially preferred as generally safe because of their known low toxicity 0000 o o and/or known use as food additives. Another distinct advantage of the use 0of the polycarboxylic acids and metal salts thereof as stabilizers is their o 0 lower cost as compared to the polyvalent fatty acid metal salts.

O 0 0 o Many of the polycarboxylic acids and metal salts thereof are commercially available. For example, the dimers and trimers of the C18 0 0 unsaturated frtty acids, and adipic and azelaic acids are readily available.

0 00 a, 0 Do The amount of the polycarboxylic acids and metal salts thereof 00 stabilizers used to achieve the desired enhancement of physical stability B 00 and apparent viscosity increase will depend on such factors as the nature of the polycarboxylic acids and metal salts thereof, the nature and amount 0 of the thixotropic agent, detergent active compound, inorganic salts, .a oS especially TPP, other LADD ingredients, as well as the anticipated storage and shipping conditions.

Generally, however, amounts of the polycarboxylic acids and metal salts thereof stabilizing agents in the range of from about 0.001 to preferably from about 0.01 to especially preferably from about 0.05 to provide the increase in apparent viscosity -and the long term stability and absence of phase separation upon standing or during transport at both low and elevated temperatures as are required for a commercially acceptable product.

-18- 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 polycarboxylic acids and metal salts thereof not only increases physical stability but also provides a simultaneous increase in apparent viscosity.

The method of formulating the compositions is not critical.

1. According to one method of mqking these compositions, one should dissolve or disperse first all the inorganic salts, i.e. carbonate (when employed), silicate and tripolyphosphate, in the aqueous medium.

O 0 Thickening agent is added last. The foam depressor (when employed) is o0000 preliminarily provided as an aqueous dispersion, as is the thickening o agent. The foam depressant dispersion, caustic soda (when employed) and inorganic salts are first mixed at elevated temperatures in aqueous solution (deionized water) and, thereafter, cooled, using agitation throughout.

Bleach, surfactant, polycarboxylic acid and metal salt thereof stabilizer o o° and thickener dispersion at room temperature are thereafter added to the s o cooled (25-35 0 C) solution. Excluding the chlorine bleach compound, total o0o0 salt concentration (NaTPP, sodium silicate and carbonate) is generally 0 0& about 20 to 50 weight percent, preferably about 30 to 40 weight percent in the composition.

0 oa 2. A preferred method for mixing the ingredients of the LADD 0 formulations involves first forming a mixture of the water, foam suppressor (when employed), detergent, polycarboxylic acid and metal salt thereof physical stabilizer (fatty acid) and thixotropic agent, e.g. clay. These ingredients are mixed together under high shear conditions, 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.

Preferably, 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 I have been obtained by adding the remaining ingredients in the following sequence: sodium hydroxide, alkali metal carbonate, sodium silicate, alkali metal tripolyphosphate (hydrated), alkali metal tripolyphosphate (anhydrous or up to 5% water), bleach (preferably, sodium hypochlorite) and sodium hydroxide.

3. In accordance with another method of carrying out the present invention the ingredients are simply added together in the order listed below with gentle stirring.

Weight Deionized Water 35-45 Color 1-3 Clay .2-4 o 15 Polycarboxylic Acid and Metal And Ammonium Salts Thereof Stabilizer .01 to 0.2 Organic Detergent Active Material 0.1-5 Anti-foam Agent 0.1-5 NaOH 0.5-6 Sodium Carbonate (Soda Ash) 2-9 Sodium Silicate 5-15 Sodium Tripolyphosphate 20-30 Sodium Hypochlorite (13% available chlorine) 0.2-4 The particular order of adding the ingredients is not critical.

In each of the above three methods specific polycarboxylic acids, specific metal salts of the polyearboxyllc acids or mixtures of polyearboxylic acids and/or mixtures of metal salts of polycarboxylic acids can be used.

Other conventional ingredients may be included in these compositions in small amounts, generally less than about 3 weight percent, such as perfume, hydrotropic agents such as the sodium benzene, toluene, xylene and 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). In formulations containing an ammonium fatty acid salt stabilizer, enzymes such as glucose oxidase, catalase, lipoxidase, proteolytic and amylolytic enzymes can be used in place of the chlorine bleach. Especially preferred for colouring are the t chlorinated phthalocyanines and polysulplides of aluminosilicate which provide, respectively, pleasing green and blue tints. TO 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 polycarboxylic acids and metal and 0 *ammonium salts thereof, namely increased apparent viscosity and increased 0 physical stability of the clay based thixotropic suspension, will apply equally well to other clay based thixotropic suspensions, such as the scouring paste formulations described in the aforementioned U.S. Patent 0 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 to the accompanying examples.

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

-21- Example 1 In order to demonstrate the effect of stabilizer, a trimer of an unsaturated fatty containing liquid ADD formulation is prepared as the polycarboxylic acid acid, e.g. Empol 1042* follows.

Percent 0 0i 00 *d a 00 00D IO 4 S0 0i 0 Deionized water 41.10 Caustic soda solution NaOH) 2.20 Sodium carbonate, anhydrous 5.00 Sodium silicate, 47.5% solution of Na 2 O:SiO 2 ratio of 1:2.4 15.74 Sodium TPP (substantially anhydrous-i.e. especially moisture) (Thermphos NW) 12.00 Sodium TPP (hexahydrate) (Thermphos N hexa) 12.00 The mixture is cooled at 25-300C and agitation maintained 'throughout, and the following ingredients at room temperature are added thereto: Percent Sodium hypochlorite solution (11% available chlorine) 9.00 Monostearyl phosphate 0.16 DOWFAX 3B-2 (45% Na monodecyl/didecyl diphenyl oxide disulphonate-aqueous solution) 0.80 Physical stabilizer (fatty acid or fatty acid salt) X Pharmagel H 2.00 There are three formulations prepared in which X aluminum stearate and X 0.2% Emphol 1040 trimer acid.

are adjusted to 100% by adjusting the water content.

X 0.10% The formulations *The Empol 1040 is the trimer of a C18 unsaturated fatty acid and is supplied by Emery Industries, Div. of National Distillers Chemical Corp.

-22b The monostearyl phosphate foam depressant (when employed) and Dowfax 3B-2 detergent active compound and Emphol 1040 stabilizer are added to the mixture just before the Pharmagel H thickener.

The Run 1 is a control formulation which includes the monostearyl phosphate anti-foam agent, but which does not contain a polycarboxylic acid or metal salt thereof stabilizer.

The Run 2 is a control formulation of Run 1 to which has been added an aluminum stearate stabilizing agent of application Serial No. 744,754.

The Run 3 is a formulation of the present invention in which Empol 10 1040 trimer acid is used as the stabilizing agent.

,Each of the resulting liquid ADD formulations as shown in the Table 4are measured for apparent viscosity at 3 and 30 rpm. The results obtained are also shown in Table 1.

From the data reported in Table 1 the following conclusions are reached: o* 0 The incorporation of 0.1% aluminum stearate in a 2% Pharmagel H 0 00 000 containing formula Run 2 (control) leads to an increase in the apparent o 0o viscosity Table, Run 1 (control).

4 00 The incorporation of 0.2% Empol 1040 trimer acid in a 2% Pharmagel H containing formula Run 3 (invention) leads to a significant increase in the 0 00 ao4.* apparent viscosity as compared to both the control Runs 1 and 2.

TABLE

BROOK HATD 1

VISCOSITY

RUN FORMULATION 20 RPM H-2 41.10% 1 Monostearyl Phosphate= 0.16% (control) Stabilizer 0% 4,000 Pharmagel H H 20 41.0% 2 Monostearyl Phosphate 0.16% (control) Al Stearate 0.1% 8,000 Pharmagel H 11H20 41.0% 3 Monostearyl Phosphate= 0.16% (invention) Empol 1040 0.2% 11,000 Pharmagel H Measured with spindle 4 after three minutes at 20 rpm on 24 hour old samples.

-23- 0 60 *0 0 a 0Q 0 It I 010 a 0 0o 0 0 0g 0 00 0 00 00 0 0 5a Example 2 The following gel-like thixotropic liquid ADD formulation is prepared by simply mixing the ingredients in the order listed.

Weight Deionized Water 42.983 Color 0.007 Clay 1.000 Glass 11(1) 0.120 Sodium Salt of Empol 1040 Trimer Acid 0.200 Dowfax 3B-2(2) 0.800 LPKN-158 3 0.160 Caustic Soda Solution (50% NaOH) 2.400 Sodium Carbonate (anhydrous) 6.990 Sodium Silicate, 47.5% Solution of Na 2 0:SiO 2 ratio 1:2.4 13.730 Sodium tri-polyphosphate 24.000 Sodium Hypochlorite Sol. (11% available chlorine) 7.610 The Glass H is a linear polyphosphate containing approximately 26 phosphate groups.

The Dowfax 3B-2 is a 45% Na monodecyl/didecyl diphenyl oxide disulphonate aqueous solution.

The LPKN-158 is an anti-foam agent comprising a 2:1 molar mixture of mono-, di- (C 1 6

-C

1 8 alkyl esters of phosphoric acid.

In order to compare the stability of the composition similar formulations were prepared in which the sodium salt of Empol 1040 trimer acid was omitted, was substituted by aluminum stearate or stearic acid.

The formulations were tested for percentage of formulation settled from solution after standing for six weeks at 100oC and after standing for six months at room temperature (20 0 The results obtained are reported in the following Table 2.

-24cr 00 0 o ii o 00 o) 0: '0 00 'a 0 Table 2 Weight Stability Stability Stabilizer 6 wks (100 0 F) 6 mos (20 0

C)

No Stabilizer 1 8.0 Aluminum Stearate 0.20 0.0 0.0 Stearic Acid 0.20 0.0 0.0 The amount of water was adjusted to 100%.

In order to determine the effect on the amount of clay used in the formulation the above formulation was prepared using Q.2% sodium tartarate and varying the amount of clay present between 0.5 and The results obtained are reported below in Table 3.

Table 3 Wt. Sodium Salt Stability Stability Wt. Clay of Empol 1040 Acid 6 wks (100 0 F) 6 mos (200C) 0.50 0.20 <1.0 0.75 0.20 <1.0 1.00 0.20 0.0 0.0 1.25 0.20 0.0 0.0 1.50 0.20 0.0 0.0 1.75 0.20 0.0 0.0 2.00 0.20 0.0 0.0 2.00 8.0 The amount of water was adjusted to 100%.

The data reported in Table 3 show that by the addition of a small amount of sodium salt of Empol 1040 trimer acid, substantially the same or improved results in stability can be obtained using reduced amounts of clay, raaJn~ Fr~ *r~lpUr~ Paarap3;aapra~~ nr Example 3 The following gel-like thixotropic liquid ADD is prepared by simply mixing the ingredients in the order listed.

Ingredient Amount Wt% Sodium silicate (47.5% solution of Na O:SiO 2 ratio of 1:2.4) 13.74 Monostearyl phosphate 0.16 Dowfax 3B-2 0.36 Thermphos NW 12.0 Thermphos N hexa 12.0 Calcium salt of Empol 1040 0.2 cae I0£ Sodium carbonate, anhydrous o Caustic soda solution 0o (50% NaOH) 2.40 Pharmagel H o °Sodium hypochlorite solution Water balance Minor amounts of perfume, color, etc. can also be added to formulation.

The formulation was tested and was found to be stable and to have good thixotropic properties.

a- -26- Example 4 Following the procedure of Example 2, formulations are prepared using the dimers of a C18 unsaturated fatty acid, per se, and K and Na salts of the trimers of a C18 unsaturated fatty acid and Al, Zn, Ca and Mg salts of the trimers of a C18 unsaturated fatty acid and stable formulations having good rheological and thixotropic properties are obtained.

Example The procedure of Example 2 is followed and a formulation is prepared in which about 1% of glucose oxidase enzyme is used in place of the hypochloride bleach and using the ammonium salt of the trimer of a C18 !A unsaturated fatty acid as the stabilizing agent. The formulations are tested and are found to have good rheological and thixotropic properties.

Example 6 S F w15 The procedure of Example 2 is followed and formulations are prepared p using disodium adipic acid and disodium azelaic acid salts, respectively, as the stabilizers. The formulations are tested and are found to have good rheological and thixotropic properties.

In addition to the superior physical stability, thixotropy and cleaning performance this invention has the additional significant advantage of not )requiring any particular order of addition of the respective ingredients.

All of the ingredients can be added in any order or simultaneously to a single pot, mixer, etc., and stirred until a uniform homogeneous mixture is obtained. Mixing can be done at room temperature or at elevated temperature. It is not necessary to premix any of the ingredients or to use different shear mixing conditions.

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.

-27-

Claims (23)

1. An aqueous thixotropic liquid composition comprising a clay thixotropic agent, at least one carboxylic acid stabilizer selected from a dimer or trimer of a C 8 to C 22 unsaturated fatty acid, or metal or ammonium salt thereof in an amount effective to increase the apparent viscosity and the physical stability of the composition, water, and at least one additional ingredient selected from the group consisting of organic detergents, pH modifying agents, bleach, enzyme, detergent builder, sequestering agent, foam inhibitors and mixtures thereof.

2. The composition of claim 1 wherein the stabilizer comprises a monovalent metal or ammonium salt of a dimer S or trimer of a C 8 to C 2 2 unsaturated fatty acid. 8 22

3. The composition of claim 1 wherein the stabilizer comprises a polyvalent metal salt of a dimer or trimer of a C 8 to C 22 unsaturated fatty acid.

4. The composition of claim 1 wherein the stabilizer is oOOD present in an effective amount of from about 0.001 to 1% e by weight. o o 5. The composition of claim 1 wherein the stabilizer is Spresent in an effective amount of from about 0.01 to Sby weight. 4 I 6. A method for cleaning soiled dishware which comprises 0 contacting the soiled dishware in an automatic dishwashing machine in an aqueous washbath having dispersed therein an 4 a* effective amount of the composition of claim 1.

7. A method for improving the stability of an aqueous, gel-like thixotropic composition having a small but effective amount of a clay-thixotropic agent which comprises including in the composition an stabilizing amount of a dimer or trimer of a C 8 to C 22 unsaturated fatty acid or metal or ammonium salt'thereof. \1 -29- 0 0 00.-~l 0 a 0 00 0 0 0 00 0 0 0 100 0 00 o 0o

8. An aqueous thixotropic automatic dishwasher composition comprising approximately by weight: 5 to 35% alkali metal tripolyphosphate; 2.5 to 20% sodium silicate; 0 to 9% alkali metal carbonate; 0.1 to 5% chlorine bleach stable,, water-dispersible organic detergent active material; 0 to 5% chlorine bleach stable foam depressant; chlorine bleach compound in an amount to provide about 0.2 to 4% of available chlorine; thixotropic thickener in an amount sufficient to provide the composition with a thixotropy index of about 2 to 0 to 8% of sodium hydroxide; a dimer or trimer of a C 8 to C 2 2 unsaturated fatty acid as a physical stabilizer in an amount effective to increase the apparent viscosity and to increase the physical stability of the composition; and balance water.

9. The composition of claim 8 wherein the polycarboxylic acid physical stabilizer is present in an amount of from about 0.01 to

10. The composition of claim 8 wherein the polycarboxylic acid physical stabilizer is present in an amount of from about 0.05 to 0.2%.

11. The composition of claim 8 wherein the polycarboxylic acid is a member selected from the group consisting of dimers and trimers of C 16 to C 2 0 unsaturated fatty acids.

12. The composition of claim 1 wherein the polycarboxylic acid comprises adipic acid.

13. The composition of claim 1 wherein the polycarboxylic acid comprises azelaic acid.

14. The composition of claim 8 wherein the thixotropic thickener is clay thickener and the amount of clay thickener is in the range of about 0.1 to 2.5% by weight. I 0 0 0 0 000 00 0 3 0 00 0 0 0 0 000 00 0 I 30 An aqueous thixotropic automatic dishwasher composition comprising approximately by weight: 5 to 35% alkali metal tripolyphosphates; 2.5 to 20% sodium silicate; 0 to 9% alkali metal carbonate; 0.1 to 5% chlorine bleach stable, water-dispersible organic detergent active material; 0 to 5% chlorine bleach stable foam depressant; chlorine bleach compound in an amount to provide about 0.2 to 4% of an available chlorine; thixotropic thickener in an amount sufficient to provide the composition with a thixotropy index of about 2 to 0 to 8% of sodium hydroxide; a monovalent metal salt of a dimer or trimer of a C 16 to C 20 unsaturated fatty acid stabilizer in o oan amount effective to increase the apparent viscosity and to increase the physical stability of the composition; and balance water. oooo 16. An aqueous thixotropic dishwasher composition comprising approximately by weight: 5 to 35% alkali metal tripolyphosphate; o0S 2.5 to 20% sodium silicate; o.o. 0 to 9% alkali metal carbonate; 0.1 to 5% chlorine bleach stable, water-dispersible °a «o organic detergent active material; 0 to 5% foam depressant; thixotropic thickener in an amount sufficient to provide the composition with a thixotropy index of about 2 to 0 to 8% of sodium hydroxide; an alkali metal or ammonium salt of a dimer or trimer of a C 16 to C 20 unsaturated fatty acid stabilizer in an amount effective to increase the apparent viscosity and to increase the physical stability of the composition; and 31 balance water.

17. The composition of claim 15 wherein the monovalent metal salt comprises a metal of the Group IA of the Periodic Table of the Elements and is present in an amount of about 0.01 to 0.5% by weight.

18. The composition of claim 17 wherein the monovalent metal salt comprises an alkali metal.

19. The composition of claim 17 wherein the monovalent metal salt comprises a metal selected from the group consisting of Na and K. The composition of claim 19 wherein the monovalent metal salt is present in an amount of about 0.05 to 0.2% by weight.

21. The composition of claim 15 wherein the thixotropic thickener is clay thickener and the amount of clay thickener is in the range of about 0.1 to 2.5% by weight.

22. An aqueous thixotropic automatic dishwasher oo composition comprising approximately by weight: a 0 5 to 35% alkali metal tripolyphosphate; 2.5 to 20% sodium silicate; 00. 0 to 9% alkali metal carbonate; **00 0.1 to 5% chlorine bleach stable, water-dispersible 0 organic detergent active material; 0 to 5% chlorine bleach stable foam depressant; o chlorine bleach compound in an amount to provide about 0.2 to 4% of an available chlorine; 0 thixotropic thickener in an amount sufficient to provide the composition with a thixotropy index of about 2 to 0 to 8% of sodium hydroxide; a polyvalent metal salt of a dimer or trimer of a C16 to C 20 unsaturated fatty acid stabilizer in an amount effective to increase the apparent viscosity and to increase the physical stability of the composition; and balance water. .2 s? 7 PKN 1 14 1 El 44 I 4 14 1 0 4 07 32

23. The composition of claim 22 wherein the polyvalent metal salt comprises a metal selected from any one of groups IIA, IIIA, IVA, VA, VIA, VIIA, IB, IIB, IIIB, IVB, VB, VIB, VIIB, and VIII of the Periodic Table of the Elements and is present in an amount of about 0.01 to by weight.

24. The composition of claim 23 wherein the polyvalent metal salt is selected from the group consisting of Mg, Ca, Ti, Zr, V, Nb, Mn, Fe, Co, Ni, Cd, Sn, Sb, Bi, Al and Zn. The composition of claim 22 wherein the polyvalent metal salt comprises a metal selected from anyone of groups II, III or IV of the Periodic Table of Elements.

26. The composition of claim 25 wherein the polyvalent metal salt is selected from the group consisting of aluminium, zinc, calcium and magnesium.

27. The composition of claim 25 wherein the polyvalent metal salt is present in an amount of 0.05 to 0.2% by weight.

28. The composition of claim 22 wherein the thixotropic thickener is clay thickener and the amount of clay thickener is in the range of about 0.1 to 2.5% by weight.

29. A method for improving the stability of an aqueous, gel-like thixotropic composition having a small but effective amount of a clay-thixotropic agent which comprises including in the composition an effective stabilizing amount of a polyvalent metal salt of a dimer or trimer of a C 1 6 to C 2 0 unsaturated fatty acid wherein the metal salt is selected from the group consisting of aluminium, zinc, calcium and magnesium. DATED this 27th day of November 1990 COLGATE-PALMOLIVE COMPANY Patent Attorneys for the Applicant: F.B. RICE CO. 1