AU606130B2 - Thixotropic clay aqueous suspensions - Google Patents

Description

m 1 18 zAxMAnsj bdouwl!! H5 pq o tillI ZAXMfAnsdONW14rIH0orna:9V 'Id 0 1 1.M 2 5 jJ± II 6 19q 11 COMMONWEALTH OF AUSTRALIA0 Patents Act 1952 CO MP LEFTE SPECIFICATION

(ORIGINAL)

Application Number Lodged Coinplete Specification Lodged Accepted Published IThis dommlent contains thec aniendlits made Undler~ Section 49 and is correct for prin ting.

Priority 12 February 1987 Related Art Name of Applicant Address of Applicant Actual Inventorha<~ Address for Service *COLGATE-PALMOLIVE COMPANY 300 Park Avenue, New York, New York, 10022 United States of America Julien Drapier; Daniel Van De Gaer; Chantal. Gallant F.B. RICE CO.

Patent Attorneys 28A Montague Street, Balmain N.S.W. 2041 Complete Specification for the invention entitleld: THIXOTROPIC CLAY AQUEOUS SUSPENSIONS The following statement is a full description of this invention including the best method of performing it known to us/me:- COGMIONWEALTH OF AUSTRALIA APPICATION ACCEPTED AND

AMENDMENT

ALOWED LODGED AT SUB-OFFICE I1 FEB 1988 Sydney_ /4! o i f rt oo a 99 o .oo.

9 I o 20 9* t t c 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 rheological 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 thixotrople thickener than in the absence of the potassium polyphosphates stabilizer.

The present invention specifically relates to automatic dishwashing detergent compositions having thixotropic properties, improved chemical and physical stability, improve stability against rheological properties variations 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 dishwasher 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 dishwasher machine dispenser.

Recent research and development activity has focused on the gel or "thixotropic" form of such compositions, scouring cleansers and automatic-dishwasher products characterized 'as thixotropic pastes.

-1a ji i: !I11 i 1:G ii

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i 1 is/arexthe first applications made in a Convention country in respect of the invention the subject of the application.

New Yor k York Declared at J S A. this 2 0 th day of January 1988 COLGATE-PALMOLIVE COMPANY By H.S. Sylvester Assistant General Counse---- Industrial Property F. B. RICE CO., To: The Commissioner of Patents Patent Attorneys, S Commonwealth of Australia Sydney.

'1 1. I *1[I I I H i I-t 0 0 a0 t 0 0l a o o a Bo o 0 0 0 0 0 00 0 0 0 «a ag 00c a a or 0 0 0 0 °o aj 0 00 a 0 0 a 8 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 cleansing 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.

The U.S. Patent Application Serial No. 744,754 filed June 14, 1985, which is assigned to applicants' assignee, is directed to thixotropic clay aqueous suspensions dishwashing detergent compositions containing aluminum stearate as physical stabilizing agent. The application Serial No.

744,754 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 aluminum stearate.

The application Serial No. 744,754 formulations, however, have in some instances experienced difficulty in achieving stability against theological properties variations with time and over wide temperature changes and have generally required relatively high clay content, such as 0.25 to The provision of automatic-dishwasher compositions in gel form having the aforedescribed properties, other than for the improvements described in the above mention application 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 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 -2-

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i .1 0-po 0 0 a e* *o p V ta f ts p p t 2 5 I205 protection for fine china glaze and pattern; sodium carbonate, generally considere, to be optional, to enhance alkalinity; a chlorine-releasing agent to aid in the elimination of soil specks which lead to water spotting; and defoamer/surfactant to reduce foam, thereby enhancing machine efficiency and supplying requisite detergency. See, for 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 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 Cl-(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 suspending agent, preferably the Smectite and attapulgite types of clay; abrasive, e.g. silica sand or perlite; and filler comprising light density powdered polymers, expanded perlite and the like, which has a bouyancy 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 NaTPP, can be included as further i I i i: 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. Maintenr-'ce 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. When present, NaTPP is limited to as stated. Foam killer is not disclosed.

In U.K. Patent Application GB 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 Snecessary for effective detergency with an automatic dishwasher. The 0 4 S' 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; .9 0.1 to 5% chlorine bleach stable, water dispersible organic 4i 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 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 10.5-14.0. 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. 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 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 finely divided hydrated sodium metasilicate, an active chlorine compound and a thickening agent which is a

I

foliated silicate of the hectorite type. Small amount of nonionic tensides and alkali metal carbonates and/or hydroxides may be used.

0 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)).

While these previously disclosed liquid ADD formulations are not Sb 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 physical stability and stability against rheological properties variations 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 rheological properties variations with time of other clay based thixotropic liquid formulations, such as scouring cleansers; dental pastes, "liquid" soaps, and the like.

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

It is another object of the invention to provide liquid ADD compositions having thixotropic properties with improved physical stability and improved stability against rheological properties variations with time.

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.

It is still another 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 potassium polyphosphates and a minor amount o 0 of a fatty acid metal salt effective to inhibit the settling of the suspended particles and to prevent phase separation.

It is a further object of this invention to improve the stability against rheological properties variations with time of aqueous thixotropic clay based compositions, especially liquid automatic dishwasher detergent pastes j I 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.

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 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 Sspecific embodiment of the invention, there is provided a normally gel-like automatic dishwasher detergent composition in which is incorporated an amount of potassium polyphosphatae and an amount of a metal salt of a long chain fatty acid which are effective to inhibit rheological properties -6-

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7 7 variations with time and effective to inhibit settling of the suspended particles, such as thixotropic agent and sodium tripolyphosphate builder salt.

The present invention provides an aqueous thixotropic liquid composition comprising a clay thixotropic agent, potassium tripolyphosphate and at least one long chain fatty acid or a metal salt of a long chain fatty acid, said potassium tripolyphosphate and said fatty acid or S* fatty acid metal salt being in an amount effective to o 10 increase the physical stability and rheological properties variations with time stability of the composition, water, and at least one additional ingredient selected from the group consisting of organic detergents, pH modifying agents, chlorine bleach, detergent builder, sequestering agent, foam inhibitors, abrasive particles and mixtures thereof, said composition containing 0.1 to 0.5 weight o percent clay, 0.5 to no more than 3.0 weight percent S potassium tripolyphosphate and 0.1 to 0.5 weight percent fatty acid metal salt.

a o 20 In accordance with a preferred embodiment, the present invention provides a normally gel-like aqueous S, automatic dishwasher detergent composition having thixotropic properties which include, on a weight basis: S(a) 5 to 35% sodium tripolyphosphate; 2.5 to 20% sodium silicate; 0 to 9% alkali metal carbonate; 0.1 to 5% chlorine bleach stable, wate' 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 thixotropy index of about to 0 to 8% sodium hydroxide; L 7a 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 composition against rheological properties variations with time; and 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.

9* .III4 I IS t t t I B 115 00 4 *0G rrLfr 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 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 (NaOH) serves the further function of neutralizing the phosphoric or phosphonic acid ester foam depressant when present. About 0.5 to 6 weight percent of NaOH and about 2 to 9 weight percent of sodium carbonate in the LADD composition are typical, r ugh it should be noted that sufficient alkalinity may be provided by i NaTPP and sodium silicate.

The NaTPP employed in the LADD composition in a range of about 8 to 35 weight percent, preferably about 20 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 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 using a 0.5:1 to 2:1 weight ratio of anhydrous to hexahydrated NaTPP, values of about 1:1 being particularly preferred.

Foam inhibition is important to increase dishwasher machine efficiency and minimize destabilizing effects which mignt occur due to the presence of excess foam within the washer during use. Foam may be sufficiently reduced by suitable selection of the type arnd/or amount of detergent -8-

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3 I 9I 4 *4 Itt 4. I 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 proportions of NaTPP 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. Particulcly effective are the alkyl phosphonic acid esters of the formula 0

II

HO-P R

OR

available for example from BASF-Wyandotte (PCUK-PAE), and especially the alkyl acid phosphate esters of the formula

O

HO-P OR

OR

available, for example, from Hooker (SAP) and Knapsack (LPKn-158), in which one or both R groups in each type of ester may represent independently a C 12 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 16 1 8 alkyl acid phosphate esters such as monostearyl/distearyl acid phosphates 1.2/1 (Knapsack) or (UGINE KULHPLAN). 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 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 -9stearate salts, for example, aluminum stearate, are also effective as foam killers.

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 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 I(NaOCI) 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 surface, 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 :20 weight percent, in the composition. The sodium silicate is generally added in the form of an aqueous solution, preferably having an Na 2 0: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 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 preferably about 0.3 to Particularly preferred surfactants heroin are the linear or branched alkali metal mono- and/or di-(C 8 14 alkyl diphenyl oxide mono and/or disulphates or disulfonates, commercially It

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00 44 4 A) 4 'A o 4 j ~AAo oj5 0 004 40 4 o 4 4 04 4 *4 4 p Q4 0) 4 44 420 p p 4 available for example as DOWFAX (Registered Trademark) 3B3-2 and DOWFAX 2A-1. In addition, the surfactant should be compatible with the other ingredients of the composition. Other suitable surfactants Include the primary alkylsuiphates, alkylsuiphonates, alkylaryl-suiphonates and sec.-alkylsulphates. Examples Include sodium C 1 0 -C 1 8 alkylsuiphates such as sodium dodecylsuiphate and sodium tallow alcoholsuiphate; sodium C 10 -C is alkanesuiphonates such as sodium hexadecyl-1-sulphonate and sodium C1-is 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 R2 I N-0, In which each R 21 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, inyristyl, pairnityl or cetyl group. Instead of an amine oxide, a corresponding surfactant phosphine oxide R R IPO or sulphoxide RR Iso can be employed. fletaine surfactants; are typically of the structure 2 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, myristyldimetylamine oxide, the corrt, phosphine oxides and sulphoxides and the corresponding bet., including dodecyl dim ethylam monium acetate,* tetradecyldlethylammioni!2m pentanoate, hexadecyldmethylammonium 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 thixotroplc properties, are lmmon 10- t he art and may be organic or Inorganic. water soluble, water-' di-.prslbjo or -11- _r *"If .J.l L.4l.'-H )tt containing 0.1 to 0.5 weight percent clay, 0.5 to no more than 3.0 weight percent potassium tripolyphosphate and 0.1 to 0.5 weight percent fatty acid metal salt.

ii 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 were 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 2,116,199A and GB 2,140,450A. 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 f i 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 preferably 0.2 to especially 0,25 to 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 phy)sical stabilizers.

2 Smectite clays include montmorillonite (bentonite), hectorite, attapulgite, smectite, saponite, and the like. Montmorillonite clays are (preferred and are available under tradenames such as Thixogel (Registered 1 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 STrademark), 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 -12- *4 t ii j i a 1 r 0 r 0 0 0 0 0o 00 0 '0 0 0 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 conained 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. Such amount is readily determined 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 Applications GB 2,116,199A and GB 2,140,450, which are assigned to applicants' assignee.

The LADD products of the U.K. Patent Applications GB 2,116,199A and GB 2,140,450 exhibit improved rheological properties as 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 extant 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 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 viscometer after 3 minutes using a No. 4 spindle one day after making. A shear rate -1 of 7.4 sec 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 I a *0 90 00 0 0 0 o 4

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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 assignee's 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. 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 Applications GB 2,116,199A and GB 2,140,450 and of the U.S.

Patent Application Serial No. 744,754 liquid aqueous ADD compositions can be significantly improved or not adversely affected while at the same time significantly improving the stability against rheological properties variations 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 exainple 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 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 40 0 C and more, the compositions containing the potassium polyphosphates and the metal salt -14u ;li ri ifi i: i r 1

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stabilizers are stable against rheological properties variations with time and temperature and do not undergo any visible phase separation.

The potassium polyphosphates 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 amount of the thixotropic 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 I AI) that can be used are in the range of from about 0.5 to preferably from about 0.80 to 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 0 00 about 10 to 20 carbon atoms, and especially preferably from about 12 to 18

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4 carbon atoms, inclusive of the carbon atom of the carboxyl group of the g0 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, unch 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, etc. Stearic acid and mixed fatty acids are preferred.

i bleach stable surfactant and buffer, e.g. silicates, carbonates, and monophosphates. Builders, such as NaTPP, can be included as further -3- L .I

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4 a 'a a a 0 L5 'asaa 0) oa bo a r O ab 4 4 The preferred metals are the polyvalent metals of Groups IIA, IIB and IIIB, such as megnesium, calcium, aluminum and zinc, although other polyvalent metals, including those of Groups IIlA, 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, 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.

Many of these metal salts are commercially available. For example, the aluminum salts are available in the triacid form, e.g. aluminum stearate as aluminum tristearate, Al(C 17

-H

3 5

COO)

3 The monoacid salts, e.g.

aluminum monostearate, AI(OH)2(C1 H35COO) and diacid salts, e.g.

aluminum distearate, Al(OH)(C 17

H

3 5

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 and mixtures of the mono- and diacid salts can be used for those metals, e.g. Zn, with valences of 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 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.

-16- 1 a.

in the washing medium and most effective at pH values best conducive to improved cleaning performance,. viz, pH 10.5-14.0. The compositions are -4- ;iI ::il S4 4 4 0* 4 4* 44 4 04 *44o R :20 44 1 4 4 4 41 3094 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 aluminum salt, with alum, alumina, etc.

Calcium stearate, i.e. calcium distearate, magnesium stearate, i.e.

magnesium distearate, aluminum stearate, i.e. aluminum tristearate, and zinc stearate, i.e. zinc distearate, are the preferred polyvalent 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, NaTPP, 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 preferably from about 0.2 to 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 rheological properties variations 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.

-17- 4 4 jl i i; I i i 1 i

I

j A cleansers; dental pastes, "lquia" soaps, anu ie Accordingly, it is an object of the invention to provide anti-settling additives for thixotropic clay aqueous suspensions. Y UL jIEr Iinm

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-j t 1

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II

t 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 10 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, mixtures of these acids, etc.

Behenic acid, stearic acid and mixed fatty acids can be used.

Many of the fatty acids are commercially available. For example, the 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 manufacturing 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 -18amount of potassium polyphosphat% and an amount or a metai saiL a long chain fatty acid which are effective to inhibit rheological properties it

I

0*s~ a a oP o 04 00 0 C 8.

15 6049 a a a 'a.

88 0 0r ~a 2 B*4 8 4 stability against rheological properties variations 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 (NaTPP, sodium silicate and carbonate) is generally about 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 suppressor, detergent, physical stabilizers (potassium tripolyphosphate and fatty acid salt) 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. 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 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, 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 -19j i ri r

~I

i i to 0 to 8% sodium hydroxide; I II n- alkalinity (properties of all the components). Especially preferred for colouring are the chlorinated phthalocyanines and polysulphides of aluminosilicate which provide, respectively, pleasing green and blue tints.

TiO 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 ft based thixotropic suspension and stability against rheological properties variations with time, will apply equally well to other clay based thixotropic suspensions, such as the scouring paste formulations described in the aaforementioned U.S. Patent 3,985,668.

w 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 Scomposition unless otherwise indicated.

ALi 1 I I Example 1 In order to demonstrate the effect of the potassium tripolyphosphate and the metal salt stabilizers liquid ADD formulations are prepared with varying amounts of the potassium tripolyphosphate and the fatty acid salt I stabilizers and thixotropic clay thickener as follows: THIXOTROPIC CLAY FORMULATIONS Percent Deionized water (adjusted to 100%) 33.06 to 42.55 Monostearyl phosphate 0.16 Dowfax 3B2 (45% Na monodecyl/didecyl diphenyl oxide disulfonate aqueous solution) 0.8 Potassium TPP (50%AI) 0 1.6 Aluminum stearate 0 0.4 Pharmagel H 0.25 SThese products are mixed under a high shear at room temperature and S Caustic soda solution (50% NaOH) 2.2 to 10.2 Sodium carbonate, anhydrous 5.00 SSodium silicate 47.5% solution of Na 2 0:SiO 2 ratio of 1:2.4 15.74 Sodium TPP Hexahydrate (Thermphos N hexa) 12.00 SSodium TPP (substantially anhydrous, i.e. especially moisture) (Thermphos NW) 12.00 Sodium hypochlorite solution (11% available chlorine) 9.00 Stitt( 2 .0 Liquid ADD formulations 1 to 9 are prepared and are measured for density, apparent viscosity at 3 and 30 rpm, and physical stability (phase separation) on standing and in a shipping test. The results obtained are shown in the following Tables I and II.

-21excess foam within the washer during use. Foam may be sufficiently reduced by suitable selection of the type and/or amount of detergent -8- I I From the data reported in Tables I and II the following conclusions are reached: The incorporation of 0.1% aluminum stearate in a 1.25% pharmagel H containing formula, Run 2 (control) leads to an increase of the physical stability without altering the apparent viscosity as compared to Run 1 (control).

The incorporation of 0.4% aluminum stearate in a 0.25% Pharmagel H containing formula, Run 3 (control), as compared to the runs 1 (control) and 3 (control) leads to an increase of the physical stability and of the apparent viscosity. The use of the higher aluminum stearate level of 0.4%, Run 3 (control), also allows the reduction of the clay level content downward from 1.25%, Run 2 (control) to 0.25%, Run 3 (control), while maintaining the physical stability of the formulation.

SThe Table I data also show that the simultaneous use of about 1.6% of potassium TPP in a 0.5% or o.3% PHARMAGEL H containing formula, Runs 4 i and 6, does not adversely affect the physical stability of the formulations while allowing the stabilization of the rheological property variations over time.

-22-

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ao .a 4 a

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tea a S -oa a- O a p a *d a a a. aD ao *b C 00 a a at a C a a a a a a 0P 4D a Sa ap TABLE I RUN FORMULATION

DENSITY

(glcm 3 BROOK LVT

VISCOSITY

(KGPS) (1) UNSHAIMN LIQUID SEPARATION (AFTER 12 WEEKS) GIASS BOTLE PLASTIC BOTTLE

SHIPPING

TEST (M) 3 30 40C RT 35 0 C 43 0 C 4 0 C RT 350C 43 0

C

RPM RPM (4) 1, H 0 =41.10i (con K PP (50%AI) =0% trol) Caustic Soda (50%A) 1.25 13 4 1-3 1-2 0 0 1-5 Alum. Stearate =0% Pharrnagel H H 0 =41.75% (con YKfPP (50%AI) =0% trol) Caustic Soda (50%AI) 1.32 28 6.8 0 0 0 01 0 Alum. Stearate =0.1% Pharmagel H =1.25% T H 0=42.45% (con X4pp (57AI)1 =0% trol) Caustic Soda (50%AI) 1.35 10 2.9 0 0 0 0 0 0 Alum. Stearate =0.4% Pharmaael H 4, H 0 =40.60% K PP (50%A) 6% Caustic Soda (50%AI) 1.33 38 6.9 0 0 0 0 0 0 Alum. Stearate =0.4% Pharmagel H I i d '1 I r,- F fy *0 o 0 000 a a 0 ot 4 0 0 0 0 0 0 0 .0 0 0 0 ~2 00.~ o go so. 0 00 04 0 0 00 S CC' 0 a g 0 CL Q a COO '200 0 '200 TABI. i continued (con trol) HO0 K PP (50%AI) Caustic Soda (50%AI) Alum. Stearate =38.5% =0% =6.2% =0.3% =A 1% 1.36 20 3.9 0 0 0 0 W6 H a =37.06% K+PP (50%6AI) 6% Caustic Soda (50%AI) 1.36 8 3.8 0 0 0 0 0 0 0 0 0 Alum. Stearate =0.3 Pharinagel H 7- H 0 =33.06% K PP (50%AI) 6% Caustic Soda (50%AI) -10.2% 1.39 20 4.1 0 0 0 0. 0 0 0 0 0 Alum. Stearate 3% Pharinagel H K0 dP 0~

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0.

0 '-4 00 :z' 0 0 o 00 PC 0 o G

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I

Notes to Table I Measured with spindle 4 after 3 rilUt i 2 4 hour old samples.

In Height (RT=room temperature=20±2OA, In Weight (RT=room temperature=20±20, Liquid separation measured after 6 wqe*ts a$4 2000 Kms in a private car (in weight in a plastic bottle).

Example 2 In order to determine the rheological properties variations with time the apparent viscosities of the Runs 2 to 7 of Example 1 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 II below.

The Table II data show that the addition of 1.6% (Runs 4, 6 and 7) leads to a strong stabilization of the rheological properties variations with time without altering the physical stabilities of the formulations at a Pharmagel H clay content of 0.3% and as compared to the Runs 3 (control) and 5 (control) which show significant apparent viscosity variations with time.

A

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.1 i__ Li a. sa a a a a. *4 en a TABLE 11 SIMULTANEOUS USE OF POTASSIUM TPP AND ALUMINUM TRISTEARATE BROOKFIELD LVT VISCOSITY AT 3 AND 30 RPM AFTER INDICATED PERIOD AT RT (KCPS) (1) RUN I DAY 2 WEEKS 4 WEEKS 6 WEEKS 12 WEEKS 2 28/6.8 24/3.4 34/8.9 53/7 41/6.7 (control) 3 10/2.9 51/6.4 48/7.6 200/ (control) 4 38/6.9 56/8 70/9.8 91/12 100/13 20/3.9 21/3.0 4615.1- 61/5.1 70/6.3 (control) 6 8/3.8 30/4 26/5.0 30/5.1 38/5.4 7 20/4.1 35/10.1 20/5.0 25/6 36/10 0 0 0 0 cn

ED

0 0 0 '1 '1 0 0 '1 0 Co c~.

0 0 0 0~ 0.

0 Co 0 (0 0 '1 0 0 0 Measured with spindle 4 after No measurement.

3 minutes in a glass bottle left on a shelf.

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1 4A I I Example 3 The following gel-like thixotropic liquid ADD same general procedures as in Example 1: Ingredient Sodium silicate (47.5% solution of Na O:SiO 2 ratio of 1:2.4 2 Monostearyl phosphate Dowfax 3B-2 Thermphos NW Thermphos N hexa Potassium TPP (50% AI) Aluminum stearate Sodium carbonate, anhydrous Caustic soda solution NaOH) Pharmagel H Sodium hypochlorite solution (11%) Water 1 is prepared following the Amount Wt% 7.40 0.16 0.36 12.0 12.0 1.6 0.25 4.9 6.2 1.25 I t' .4 4.

44 4 4 9, 4 4 4 9, 4444u balance pH 13 to 13.4 Minor amounts of perfume, color, 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 4 A gel-like thixotropic liquid ADD is prepared as in Example 3, with the change that 1.6% (50% AI) of potassium pyrophosphate is substituted for the potassium TPP. Similar results to tbr'- of Example 3 are obtained.

-27i! j i i;

I

1 III I v 5 f ec *I *1 Example The following gel-like thixotropic liquid ADD is prepared following the same general procedures as in Example 1: Ingredient Amount Wt% Sodium silicate (47.5% solution of Na 2 0:SiO 2 ratio of 1:2.4) 7.48 Monostearyl phosphate 0.16 Dowfax 3B-2 0.36 Thermphos NW 12.0 Thermphos N hexa 12.0 Potassium TPP (50%AI) 1.6 Stearic Acid 0.4 Sodium carbonate, anhydrous Caustic soda solution (50%NaOH) 3.1 Pharmagel H Sodium hypochlorite solution Water Balance iP t f 4 Minor amounts formulation.

of perfume, color, etc., can also be added to 1 -28z.-I'll I I k Example 6 The following gel-like thixotropic liquid ADD is prepared following the same general procedures as in Example 1: Ingredient Sodium silicate (47.5% solution of Na 2 0:SiO 2 ratio of 1:2.4) Monostearyl phosphate Dowfax 3B-2 Thermphos NW Thermphos N hexa Potassium TPP (50%AI) Behenic Acid Sodium carbonate, anhydrous Caustic soda solution (50%NaOH) Pharmagel H Sodium hypochlorite solution (11%) Water Amount Wt% 7.48 0.16 0.36 12.0 12.0 1.6 0.2 6.2 Balance S t St t t Minor amounts of perfume, color, 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.

-29- I I

Claims (5)

1. 4. I!. I 441 *4 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. An aqueous thixotropic liquid composition comprising a clay thixotropic agent, potassium tripolyphosphate and at least one long chain fatty acid or a metal salt of a long chain fatty acid, said potassium tripolyphosphate and said fatty acid or fatty acid metal salt being in an amount effective to increase the physical stability and rheological properties variations with time stability of the composition, water, and at least one additional ingredient selected from the group consisting of organic detergents, pH modifying agents, chlorine bleach, detergent builder, sequestering agent, foam inhibitors, abrasive particles and mixtures thereof, said composition containing 0.1 to 0.5 weight percent clay, 0.5 to no more than 3.0 weight percent potassium tripolyphosphate and 0.1 to 0.5 weight percent fatty acid metal salt. 2. The composition of claim 1, wherein the metal salt comprises a polyvalent metal salt of a metal of Group II, III or IV of Mendeleev's Period Table of the Elements of a long chain fatty acid having from 8 to 22 carbon atoms or mixture of two or more of such fatty acids. 3. The composition of claim 1, wherein the polyvalent metal is aluminium, zinc, calcium or magnesium. 4. The composition of claim 1, wherein the fatty acid meta salt is aluminium stearate, calcium stearate or magnesium stearate. An aqueous thixotropic automatic dishwasher composition comprising approximately by weight: 5 to 35% sodium 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 4 r 4 M Ij and cumene sulphonates, preservatives, dyestuffs and pigments and the like, all of course being stable to chlorine bleach compound and high -19- 31 0.2 to 4% of available chlorine; clay thixotropic thickener in an amount sufficient to provide the composition with a thixotropy index of 2 to 0 to 3% of sodium hydroxide; a physical and rheological properties stabilizing agent comprising potassium tripolyphosphate in an amount of 0.5 to 3% by weight and a polyvalent metal salt of a long chain fatty acid; and balance water.
2. 6. The composition of claim 5, wherein the metal salt stabilizer is a polyvalent metal salt of an aliphatic fatty acid having from 8 to 22 carbon atoms.
3. 7. The composition of claim 6, wherein the acid has from 12 to 18 carbon atoms.
4. 8. The composition of claim 5, wherein the metal salt stabilizer is the aluminum salt or zinc salt of said fatty 1 acid.
5. 9. The composition of claim 5, wherein the metal salt stabilizer is aluminum stearate. The composition of claim 5, wherein the metal salt stabilizer is zinc stearate. DATED this 24 day of September 1990 COLGATE-PALMOLIVE COMPANY Patent Attorneys for the Applicant: F.B. RICE CO. p? sl