AU610100B2 - Aqueous liquid dishwasher composition containing a stabilized enzyme system - Google Patents

Description

-I .i-i COMMONWEALTH OF AUSTRALIAA

I

Patents Act 1952 C O M P L E T E S P E.C I'F I-_CA T I O N

(ORIGINAL)

Application Number Lodged Complete Specification Lodged Accepted Published Priority Related Art This d'umencrit contaI's the Sai c m nlt: i .rt S1 December 1986 an c c i 15 December 1986 Name of Applicant COLGATE-PALMOLIVE COMPANY Address of Applicant :300 Park Avenue, New York, New York, 10022, United States of America Actual Inventor/s Andre Crutzen; Myriam Delvaux; Leopold Laitem Address for Service F.B. RICE CO., Patent Attorneys, 28A Montague Street, Balmain N.S.W. 2041 Complete Specification for the invention entitled: AQUEOUS LIQUID DISHWASHER COMPOSITION CONTAINING A STABILIZED ENZYME SYSTEM The following statement is a full description of this invention including the best method of performing it known to us:- E7 i 22fU the invention the subject of the application.

New York. New York Declared at v 2 4 this 24tn day of November 1987 CO AT PAMOVE COMPANY By H.S ylvester Ass 'ant General Industrial Property F. B. RICE CO., L To. .The TnhJmmi oner of Patents p .ALntrn 2 2 CROSS REFERENCE APPLICATIONS The Australian Patent Application No. 80068/87, which is assigned to applicants' assignee discloses a built aqueous liquid laundry detergent composition containing an enzyme stabilizing system comprising a boron compound, an alpha-hydroxy carboxylic acid, casein and an enzyme.

The Australian Patent application No. 77427/87, which is also assigned to applicants' assignee discloses a thixotropic clay aqueous dishwasher composition containing aluminum stearate as physical stabilizing agent.

SUMMARY

.The present invention relates to aqueous built diswatea)compositions containing a stabilized enzyme system. The stabilized enzyme system contains a boron compound, an alpha-hydroxy carboxylic acid, casein and an enzyme. The present invention particularly relates to aqueous liquid thixotropic clay d4shwa-e composition containing a stabilized enzyme system comprising a boron I0 compound, e.g. sodium borax, an alpha-hydroxy carboxylic .,20 acid, e.g. lactic, tartaric and citric acid, casein and an o enzyme, e.g. proteolytic and amylolytic enzymes. The "o0 present inveition specifically relates to automatic S0 dishwashing detergent compositions containing a stabilized o" enzyme system having enzyme stability and physical stability and which are readily dispersible in the washing medium to provide effective cleaning of dishware, glassware, china and the like.

o The powder built dishwasher detergent compositions 0 and the aqueous built dishwasher detergent compositions, including thixotropic dishwasher compositions that are 0o:o.0 presently available do not contain stabilized enzyme systems.

BACKGROUND OF THE INVENTION This invention relates to built, enzyme-containing aqueous liquid dishwasher detergent compositions suitable i 3 tor cleaning of dishware, glassware, china, utensils and the like. More particularly, the invention relates to aqueous enzyme-containing liquid dishwasher detergent compositions which contain one or more detergent builders and which are characterized by being stable compositions.

The automatic dishwashing compositions, hereinafter also designated ADD, generally 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 pattern; sodium carbonate, generally considered to be optional, to enhance alkalinity; a chlorine-releasing agent to aid in the elimination of soil specks which lead to water spotting and to aid in the elimination of stainy soils like tea and coffee; and defoamer/surfactant to reduce foam, thereby enhancing machine efficientcy and supplying requisite detergency.

0°o See, for example, SDA Detergents in Depth, "Formulations 0 Aspects of Machine Dishwashing". Thomas Oberle (1974).

ooo ooo Cleansers approximating to the afore described o compositions are mostly liquids or powders.

S0 The use of a chlorine releasing agent, however, in 00° some dishwasher formulations has been objectionable because the chlorine releasing agent tends to react with other chemically active ingredients, particularly surfactant (see U.S.P. 4,115,308), thereby degrading the 00 00 suspending or thixotropic agent and impairing its 0 00 effectiveness. It is a feature of the present invention that a chlorine releasing agent is not required in the 0.0 dishwasher composition.

The formulation of stabilized enzyme-containing liquid dishwasher compositions has been a difficult problem. The desirability of incorporating enzymes into 004'.35 dishwasher detergent compositions is primarily due to the 0 00 rs~a 4 effectiveness of proteolytic and amylolytic enzymes in decomposing proteinaceous and starchy materials found on dirty dishes and utensils, thereby facilitating the removal of leftover food materials, such as gravy, egg, tomato sauce, chocolate and the like during automatic machine dishwashing. However, enzymatic materials suitable for dishwasher compositions particularly proteolytic enzymes, are relatively expensive. Moreover, enzymes are known to be unstable in aqueous built detergent laundry compositions.

In the case of liquid laundry detergent compositions containing a phosphate builder, the problem of enzyme instability is known to be particularly acute. Primarily this is because phosphate detergent builders have a destabilizing effect on enzymes. Moreover, the incorporation of a phosphate builder into a liquid dishwasher detergent composition poses an idditional p-oblem, namely the ability to form a stable single-phase composition; the solubility of sodium tripolyphosphate, 20 for example, being relatively limited in aqueous compositions, and especially in the presence of anionic 0o0 detergents.

0 0°0 The stabilization of enzymes in detergent 0 compositions having a high alkalinity is also difficult because high alkalinity is known to deactivate enzymes.

While it is possible to reduce the pH to improve enzymes stability this negates to some extent the benefit of the builders. The stabilized enzymes system of the present o invention provides enzyme stability even at relatively high pH's, up to pH 10-12. The higher pH's, e.g. pH 10-12, are known to give better detergency and are preferred. Reducing the detergent composition pH, e.g. to pH 7.5 to 9.5 can increase the stability of the enzyme, but reduces suds life and the benefits of the builder, i.e. detergency.

ii 5 PRIOR ART PATENTS Ulrich U.S.P. 4,431,559 discloses a thixotropic automatic dishwasher composition comprising an aqueous solvent, a thickening agent, a source of chlorine, an anionic surfactant, builder salts and a buffer system to stabilize the chlorine source.

U.S.P. 3,558,498 discloses a granular laundry detergent composition containing stabilized enzymes, sodium perborate trihydrate, anhydrous trisodium phosphate, anhydrous calcium sulfate and soluble or dispersible proteins having a molecular weight of 5,000 to 1,000,000, e.g. casein having a molecular weight of 50,000 to 200,000.

U.S.P. 3,560,392 (CINP 3,558,498) discloses a granular laundry detergent composition containing organic detergent, alkaline builder salt, a stabilized enzyme and a stabilizing amount of proteinaceuos collagen having a molecular weight of 5,000 to 250,000.

S0 U.S.P. 4,238,345 discloses a liquid laundry detergent 0 oo20 composition in which the enzyme is stabilized by adding an 0 antioxidant and a hydrophilic polyol having 2 to 6 0 hydroxyl groups. Patentee states in column 1 that calcium salts combined with proteins and glycerol combined with proteins have been used to provide enzyme stabilizing systems in aqueous liquid laundry detergents.

U.K. Patent Application G.B. 2,079,305 discloses an aqueous built liquid laundry detergent composition containing an enzyme in which the enzyme is stabilized by a mixture of a polyol and boric acid.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention there is provided a polyphosphate built aqeuous liquid dishwasher composition containing a stabilized enzyme system comprising a boron compound and an alpha-hydroxy carboxylic acid, and a proteinaceous material, e.g.

-6casein, and an enzyme.

The enzyme stabilization is obtained by premixing a boron and alpha-hydroxy carboxylic acid mixture with an enzyme and casein mixture so as to at the same time block [i 5 the enzyme catalytic sites with casein and block the enzyme structure with the mixture of the boron compound and the alpha-hydroxy carboxylic acid.

The enzyme stabilizing system of the present invention in addition to providing very good protease stabilization exhibits a very good amylase stabilization, thus allowing the use of duel protease and amylase stabilized systems in high alkaline detergent compositions.

The effective stabilization of amylase enzyme activity is surprising since it would have been expected that any amylase activity would have been destroyed at pH above 9.

In accordance with the present invention, machine washing of dirty dishware and utensils is affected by 0 contacting the dishware and utensils with a heavy duty ,20 built aqueous liquid dishwasher composition containing the oo0 stabilized enzyme system.

ooo 0 The aqueous liquid dishwasher compositions of the present invention are capable of satisfactorily cleaning dishware and utensils containing both oily and particulate food soils. Additionally, the described compositions may be employed for the presoak of badly soiled dishes to be washed in an automatic dishwasher machine.

S. The present invention is based upon the discovery i that a stabilizing enzyme system comprising a boron compound, an alpha-hydroxy carboxylic acid, a proteinaceous material, e.g. casein, and an enzyme provide an effective and efficient enzyme stabilizing effect to the aqueous liquid dishwasher compositions.

tIC In an embodiment of the present invention there is provided a built aqueous liquid dishwasher composition -7comprising an enzyme stabilizing system and a suspension of a detergent phosphate builder salt in the aqueous liquid anionic surfactant detergent.

In another embodiment of the present invention there is provided an aqueous liquid thixotropic clay dishwasher composition comprising an enzyme stabilizing system and a suspension of a detergent phosphate builder salt in the aqueous liquid anionic surfactant detergent.

Applicants have found that a stabilizing enzyme system comprising a mixture of a boron compound, an alpha-hydroxy carboxylic acid, a proteinaceous material, e.g. casein and an enzyme provided stable, effective enzyme activity over relatively long periods of time in aqueous liquid dishwasher compositions.

The dishwasher formulations of the present invention are physically stable compositions. The aqeuous liquid detergent composition of the present invention are easily pourable, easily measured and easily put into an automatic o dishwasher machine.

o0 :,20 It would be desirable to provide an aqueous liquid or o an aqueous liquid thixotropic clay dishwasher composition o contanining a stabilized enzyme system and optionally a o physical stabilizing agent.

'I Accordingly it is an object of the present invention to provide an aqueous liquid dishwasher composition containing a stabilized enzyme system.

It is another object of the invention to provide an 440 aqueous liquid thixotropic clay dishwasher composition 0, containing a stabilized enzyme system.

It is still another object of the invention to provide a stabilized enzyme system containing a boron compound, an alpha-hydroxy carboxylic acid, casein and an enzyme for adding to aqueous liquid and aqueous liquid thixotropic dishwasher compositions to provide effective proteolytic and/or amylolytic enzyme cleaning activity to 8 the dishwasher composition.

It is still another object of the invention to improve the physical stability of aqueous liquid thixotropic gel dishwasher compositions containing stabilized enzyme systems by incorporating in a thixotropic clay dishwasher composition a small effective amount of a fatty acid metal salt, physical stabilizing agent, e.g. aluminum stearate, to inhibit the settling of suspended particles and to prevent phase separation.

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 an aqueous thixotropic, e.g. normally gel-like, composition a stabilized enzyme system. In order to improve the physical stability of the dishwasher composition there can be included in the ccmposition a small effective amount of a physical stabilizer, for example, a fatty acid or a 0o fatty acid metal salt. More particularly according to a 0 ooo 020 preferred embodiment of the invention, there is provided a normally gel-like automatic dishwasher composition in u oo o which there is incorporated a stabilized enzyme system 00 o0 0 containing a boron compound, an alpha-hydroxy carboxylic 0 0 00 acid, casein and an enzyme, and a pnysical stabilizing amount of a long chain fatty acid metal salt which is effective to inhibit settling of the suspended particles ADVANTAGES OVER THE PRIOR ART .0.00.

00000 The present in-ention provides a phosphate built 0 0000 aqueous liquid dishwasher composition containing a relatively simple stabilized enzyme system which comprises 0. 0 a boron compound, an alpha-hydroxy carboxylic acid, a proteinaceous material, e.g. casein, and an enzyme. The enzyme stabilizing system provides stabilization of the active ingredient enzyme over relatively long periods of time such that small amounts of the expensive enzymes can ~1~1 9 be used.

The present invention provides an aqueous liquid phosphate built anionic surfactant dishwasher composition containing a stabilized enzyme that can be used at effective high pH of 10-12. The present invention also provides an effective and efficient dishwasher composition that does not require the use of a chlorine compound.

DETAILED DESCRIPTION OF THE INVENTION In accordance with a preferred embodiment of the present invention there is provided a normally gel-like aqueous automatic dishwasher composition having thixotropic properties which includes on a weight basis: 8 to 35% alkali metal tripolyphosphates; 0 to 20%, such as 2.5 to 20% sodium silicate; 0 to 9% alkali metal carbonate; 0 to such as 0.1 to 5% water dispersible organic detergent active material, thixotropic clay thickener in an amount 0. sufficient to provide the composition with thixotropy index of 0 to 10.0, such as about 2.5 to o 0.5-2.0% boron compound, oooooa S° 1.5-4.0% alpha-hydroxy carboxylic acid; o 1-4.0% casein; 0 0.5-2.0% enzyme; 0 to 5% foam depressant; 0 to 8% sodium hydroxide; 0 to 2% of a long chain fatty acid metal salt; and 0 the balance water.

"Also related to this 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 =I 10 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.

According to the present invention the activity of the enzyme is stabilized over a relatively long period of time such that smaller amounts of the enzyme provide effective enzyme cleaning acticity. The enzyme activity is stabilized by the addition of small effective amounts of a stabilized enzyme system comprising a boron compound and an alpha-hyrdroxy carboxylic acid, and a proteinaceous material, e.g. casein and an enzyme. The stabilized enzyme system is used in aqueous phosphate built anionic detergent compositions.

Stabilized Enzyme System The stabilized enzyme system is preferably prepared separately and then added to the dishwasher composition.

00 O 20 The stabilized enzyme system is preferably prepared in a three step procedure described as follows.

00~, 01 A boron compound is added to an alpha-hydroxy carboxylic acid or salt to obtain a first mixture.

2. The proteinaceous material, e.g. casein is added to an aqueous alkali solution and the enzyme is added to the aqueous alkali solution to obtain a second mixture.

3. The boron and alpha-hydroxy carboxylic acid mixture obtained in step 1 is then mixed with the proteinaceous 0 40 material and enzyme mixture obtained in step 2 to obtain the premix stabilized enzyme system of the present invention.

The above step 1 mixture and step 2 mixture can each separately be added to the dishwasher composition, however, the best enzyme stabilizing results are obtained by premixing the step 1 and 2 mixtures and then adding the premixed mixture to the dishwasher composition.

Though applicant does not wish to be limited to any theory of how the stabilized system operates, it is believed that the boron compound reacts with the alpha-hydroxy carboxylic acid or the alpha-hydroxy polycarboxylic acid to form a boric ester. The boric acid ester is believed to react on the enzyme and block its istructure in the active conformation so as to protect it from denaturation. The proteinaceous material is believed to block the enzyme catalytic sites hence preventing the digestion of other enzymes molecules during product storage.

The stabilized enzyme system comprises: Boron compound, e.g. Borax, in an amount of 0.4 to preferably 0.75 to 2.0 and more preferably 0.9 to 1.2 parts by weight.

Alpha-hydroxy carboxylic acid, in an amount of 1 to preferably 1.5 to 4.0 and more preferably 1.8 to 3.6 parts by weight.

"o Proteinaceous material, e.g. casein, in an amount of 0o..20 1 to 6.0, preferably 1 to 4.0, for example about 1.0 to parts by weight.

0 0 Enzyme in an amount of 0.5 to 3.0, preferably 0.5 to "o 2.0 and more preferably 0.5 to 1.0 parts by weight.

0 The weight ratio of alpha-hydroxy carboxylic acid to boron compound, can be 7:1 to 1:1, preferably 4:1 to 1:1, and more preferably 3:1 to 2:1.

SThe weight ratio of proteinaceous material, e.g.

o0 0* casein, to enzyme can be 8:1 to 1:1, preferably 4:1 to 1:1 o°o" and more preferably 4:1 to 2:1.

0 0a A preferred stabilized enzyme system of the present 0 invention comprises the following constituents in the amounts indicated.

L

12 Parts By Weight Borax (Na 2

B

4 0 7 .10H 2 0) 0.75 to Alpha-hydroxy carboxylic acid 1.5 to Casein 1.0 to Enzyme 0.5 to The stabilized enzyme system can be added to dishwasher composition in an amount of 10 to 30 parts of stabilized system to 90 to 70 parts by weight of detergent composition, preferably 15 to 25 parts of stabilized system to 85 to 75 parts by weight of dishwasher composition and more preferably 15 to 20 parts of stabilized system to 85 to 80 parts by weight of dishwasher composition. The stabilized enzyme system is added to the dishwasher composition in a manner such that the weight percent of active ingredients of the enzyme system in the dishwasher composition are equivalent to the above mentioned parts by weight of the active ingredients in the stabilized enzyme system.

"oo A detailed description of the stabilized enzyme o ooo 20 system in presented in the above mentioned application _800 g7 o ~ij i whic is incorporated in its entirety herein by reference.

00 0 o .0 The stabilized enzyme of the present invention can be 0 0. used in aqueous liquid dishwasher compositions, aqueous liquid thixotropic dishwasher compositions and in powder or granular dishwasher compositions.

The stabilized enzyme systems of the present o invention in a preferred embodiment is added to aqueous 0 o00 liquid thixotropic dishwasher compositions.

Alpha-hydroxy Carboxylic Acids The alpha-hydroxy carboxylic acids that can be used in the present invention are the organic carboxylic acids having 3 to 8 carbon atoms, including 1 to 3 carboxylic acid groups, and 1 to 3 hydroxy groups.

The preferred carboxylic acids are the alpha-hydroxy i 13 carboxylic acids having 3 to 6 carbon atoms, including 1 to 3 carboxylic acid groups, and 1 to 2 hydroxy groups.

Suitable alpha-hydroxy carboxylic acids include malic acid (HOOCCHOHCHgCOOH), tartaric acid (HOOCCHOHCHOHCOOH), lactic acid (HOOCCHOHCH 3 and citric acid (HOOCCH2C(OH)COOHCH2COOH). The preferred alpha-hydroxy carboxylic acids are tartaric, latic and citric acids. The citric acid is the most preferred. The alpha-hydroxy carboxylic acids per se can be used or the acids can be used as their alkali metal salts, such as sodium and potassium salts.

Boron Compounds The boron compounds that are used in the dishwasher compositions of the present invention are those which are water soluble andi when added to water form boric acid or an alkali metal salt of boric acid. The boron compounds that can be used include boric acid, boric oxide or an alkali metal borate. Suitable alkali metal borates are sodium and potassium ortho-, pyro- and meta-borates, polyborates and borax (Na 2 4 0 7 .10H The preferred boron compounds are boric acid, sodium borate (Na 3 Bo 3 and borax Na 2

B

4 0 7 .10H 0).

SEnzymes The enzymes to be incorporated in the dishwasher compositions of the present invention can be proteolytic or amylolytic enzymes or mixtures thereof. The proteolytic enzymes suitable for the present invention Sinclude the various commerical liquid, powder or slurry o enzymes preparations which have been adapted for use in detergent compositions.

Though the incorporation of the enzymes in the composition is most convenient in liquid form, the enzymes in the slurry form have proven to be useful. Suitable liquid enzyme preparations include "Alcalase" and "Esperase" sold by Novo Industries, Copenhagen, Denmark, 14 "Maxatase" and "Maxacal" sold by Gist-Brocades, Delft, The Netherlands and Optimase, sold by Miles Kali Chemie.

Suitable proteolytic enzymes include subtilisin, bromelin, papain, trypsin and pepsin. Suitable enzymes include iiquid protease and liquid amylase. The enzymes are preferably used as their solutions. A preferred enzyme is Esperase 8L in the form of a solution. Suitable alpha-amylase liquid enzyme preparations are those sold by Novo Industries and Gist-Brocased under the tradenames "Termamyl" and "Maxamyl", respectively. A preferred enzyme is Termamyl 120L. "Esperase" 8L is preferred for the present compositions because of its activity at the higher pH values corresponding to the built detergent compositions. Another preferred enzyme is Esperase because of its high activity at 60 0 C and its low activity at room temperature. Further, the Esperase is stable at high pH, thus allowing a higher pH in the final product and better detergency.

S° Proteinaceous Material c-420 One of the enzyme stabilizing material constituents of the present invention is a proteinaceous material, for Sexample casein. The proteinaceous materials are used as i their water soluble alkali metal salts sodium and potassium) and/or are dispersed in an aqueous medium to which the enzyme is added.

Proteins which are soluble or dispersible in water are utilized herein in an effective amount to stabilize the enzymes. Example of proteins which are soluble or dispersible in water and suitable for use herein include casein (average molecular weight 50,000 to 200,000); S Wilsons Protein WSP-X-1000 (a solubilized collagen having an average molecular weight or about 10,000) and Wilson's Hydrolyzate Cosmetic 50, both marketed by Wilson's Pharmaceutical Chemical Company; and Collagen Hydrolyzate Cosmetic 50, marketed by Maybrook, Inc. A I I i ~1 i-I I iii L- 15 preferred casein protein is sold under the trade name "Sodium Caseinate" by Bridal (France) or Dena, A.G.

(Germany). The Sodium Caseinate is a mixture of several caseins of different molecular weights. The proteins, e.g. casein, are normally available as powders. The proteins such as casein exist as long chemical chains. As powders the chains are folded upon themselves and form hydrogen bonds holding the protein in a globular form.

Unravelling or denaturing the protein involves rupturing these bonds to form a looser more raprA" structure. The proteins can be denatured by boiling, th. use of acids, alkalis and various detergents. The unravelled or denatured proteins are more easily digested by enzymes, hence provide a better stabilizing effect, i.e. provide better enzyme stability. The denaturing makes the protein more effective as a stabilizer. The protein, e.g. casein, is used in an amount sufficient to effect stabilization of the enzyme activity.

Dishwasher Detergent Composition 0o 00 20 Generally, the thixotropic clay aqueous dishwasher o ooo0 composition effectiveness is related to alkanlinity, solubility in washing medium, and foam 0 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 12.5 and most preferably at least about 11.5. At the relatively lower pH values, the dishwasher detergent product is too viscous, i.e. solid-like, and thus not readily fluidized under the shear-force levels created within the dispenser cup under normal machine operating conditions. In essence, the composition loses much, if not all, of its thixotropic character. Addition of NaOH is thus often needed to increase the pH to within the above ranges, and to increase flowability properties.

The presence of carbonate is also often needed herein, since it acts as a buffer helping to maintain the desired 16 16 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 to 3 weight percent of NaOH and about 2 to 9 weight percent of sodium carbonate in the LADD composition are typical, although it should be noted that sufficient alkalinity may be provided by the NaTPP and sodium silicate. The sodium silicate can be employed in amounts of 0 to 20 weight percent, preferably 2.5 to 20 weight percent and more preferably 5 to 15 weight percent.

The NaTPP employed in the LADD composition in a range of about 8 to 35 weight percent preferably about 20 to weight percent. The NaTPP may be anhydrous of hydrated, "0 including the stable hexahydrate with a degree of °6::20 hydration of 6 corresponding to about 18% by weight of water or more. Actually, in view of the stability of the hexahydrate, the presence of some water of hydration is highly effective, serving it is thought to form seeds of 'the stable hexahydrate which expedites hydration and solubilization of the remaining NaTPP particles. If only the hexahydrate is used, the detergent product may be too liquid and may have little if any thixotropic character.

Conversely, if only the anhydrous NaTPP is used, the product may, in some cases, be too thick and, therefore, unsuitable. 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 17 which might occur due to the presence of excess foam within the washer during use. Foam may be sufficiently reduced by suitable selection of the type and/or amount of detergent active material, the main foam-producing component. The degree of foam is also somewhat dependent on the hardness of the wash water in the machine whereby suitable adjustment of the 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 foam depressant or inhibitor where a low foam LADD is desired. Particularly effective are the alkyl phosphonic acid esters of the formula 0 It HO- P-R

OR

0 oo I#*20 available, for example, from BASF-Wyandotte (PCUK-PAE), S* and especially the alkyl acid phosphate esters of the formula 0 0 i25 I 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 20 alkyl group.

Mixtures of the two types or mixtures of mono- and di-esters of the same type, may be employed. Especially preferred is a mixture of mono- and di-C 16 18 alkyl acid li_ 18 phosphate esters such as monostearyl/distearyl acid phosphate 1.2/1 (Knapsack). When employed, proportions of 0.1 to 5 weight percent, preferably about 0.1 to weight percent of foam depressant in the composition is typical, the weight ratio of detergent active component to foam depressant generally ranging from about 10:1 to 1:1 and preferably about 4:1 to 1:1. Other defoamers which may be used include, for example, the known silicones.

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 to 20 weight percent, preferably about 5 to 15 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 1:2.2 to 1:2.8. At this point, it should be mentioned that most of the other components of this composition, especially NaOH, °o foam depressant and thixotropic thickener, are also often added in the form of a preliminary prepared aqueous dispersion or solution.

Detergent active materials useful herein are the organic anionic, amine oxide, phosphine oxide, sulphoxide o or betaine water dispersible surfactant types. The anionic surfactants are preferred. The surfactants, e.g.

anionic surfactants are used in amounts ranging from about 0.1 to preferably about 0.3 to Particularly S. preferred surfactants herein are the linear or branched o o' alkali metal mono- and/or di-(Cs 14 alkyl diphenyl oxide mono- and/or di-sulphates, commerically available, for example, as DOWFAX (Registered Trademark) 3B-2 and DOWFAX 2A-1. In general, the paraffin sulphonates tend to impair, if not destroy, thixotropy, having been found to O. unduly increase viscosity causing severe shearing force 35 problems. In addition, the surfactant should be I i 19 compatible with the other ingredients of the composition.

Other suitable surfactants include the primary alkylsulphates, alkylsulphonates, alkylaryl-sulphonates and sec.-alkylsulphates. Example include sodium CIo-C 18 alkylsulphates such as sodium dodecylsulphate and sodium tallow alcoholsulphate; sodium C10-C 18 alkanesulphonates such as sodium hexadecyl-l-sulphonate and sodium C 12 -C18 alkylbenzenesulphonates such as sodium dodecylbenzenesulphonates. The corresponding potassium salts may also be employed. Examples of suitable alkyl sulfonates are the C, 0 C18 primary alkyl sodium and potassium sulfonates, with the C 10

C

1 5 primary normal alkyl sodium sulfonate salt being preferred.

As other suitable surfactants or detergents, the amine oxide surfactants are typically of the structure

R

2 R'N-O, in which each R represents a lower alkyl group, for instance, methyl, and R 1 represents a long chain alkyl group having from 8 to 22 carbon atoms, for instance a lauryl, myristyl, palmity or cetyl group.

Instead of an amine oxide, a corresponding surfactant phosphine oxide R 2

R

1 PO or sulphoxide RR 1 SO can be employed. Betaine surfactants are typically of the structure R 2

R

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, myristyldimetylamine oxide, S the corresponding phosphine oxides and suplhoxides, and o the corresponding betaines, including dodecy2dimethylammonium 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 J~1 20 the art, are described, for example, in U.S. Patents 3,985,668 and 4,271,030.

Thixotropic thickeners, i.e. thickeners or suspending agents which provide an aqueous medium with thixotropic properties, are known in the art and may be organic or inorganic water soluble, water dispersible or colloid-forming, and monomeric or polymeric, and should of course be stable in these compositions, e.g. stable to high alkalinity. Those especially preferred generally comprise the inorganic, colloid-forming clays of smectite and/or attapulgite types. The organic clay thixotropic thickeners can also be used. 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 disclosed in GB 2,116,199A and GB 2,140,450A. In accordance with the present invention, amounts of the inorganic S colloid-forming clays of the smectite and/or attapulgite types in the range of from about 0.25 to preferably S 0.50 to especially 1.0 to are generally o °a sufficient to achieve the desired thixotropic properties S and Bingham plastic character. Smaller amounts of the thixotropic agent can be used when used in combination with the fatty acid metal salt physical stabilizer.

Smectite clays include montmorillonite (bentonite), hectorite, attapulgite, smectite, saponite, and the like.

o Montmorillonite clays are preferred and are available under tradenames such as Thixogel (Registered trademark) o 1;30 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

L

21 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 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 35 to 65 weight percent, preferably about 40 to 55 weight percent. The water should also be preferably deionized or softened.

The description of the LADD product, except as otherwise noted, conforms generally to the compositions as S disclosed in the aforementioned U.K. Patent Applications GB 2,116,199A and GB 2,140,450A, which are assigned to Sapplicant's assignee.

The LADD products of the prior U.K. Patent Application GB 2,166,199A and GB 2,140,450A exhibit improved rheological properties as evaluated by testing product viscosity as a function of shear rate. The Scompositions exhibited higher viscosity at a low shear -Irate and lower viscosity at a high shear Late, the data °O1530 indicating efficient fluidization and gellation well within the shear rates extent within the standard dishwasher machine. In practical terms, this means 0 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 1~ 22 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 after 3 minutes using a No. 4 spindle. A shear rate of 7.4 sec- 1 corresponds to a spindle rpm of about 3. An approximate ten-fold increase in shear rate produces about a 3- to 9-fold reduction in viscosity. With prior ADD gels, the corresponding reduction in viscosity was only about 2-fold. Moreover, with such compositions, the initial viscosity taken at about 3 rpm was only about 2,500 to 2,700 cps. The composition 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 application No No.A M No. mentioned above is based upon the discovery that the physical stability, i.e.

resistance to phase separation, settling, etc., of the U.K. Patent Applcations GB 2,116,199A and GB 2,140,450 0C liquid aqueous ADD compositions can be significantly 000 improved, without adversely affecting, and in some cases, advantageously affecting, their rheological properties by oo~s adding to the composition a small but effective amount of a metal salt of a long chain fatty acid.

As an example of the improvement on 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 2- to 3-fold with A ZjX Al

-L

23 the incorporation of as little as 0.2% or less, e.g.

0.16%, of the fatty acid metal salt stabilizer. A the same time, the physical stability may be improved to such an extent that even after a long time, twelve weeks or longer, over temperature ranges extending from near freezing to 40 0 C and more, the compositions containing the fatty acid metal salt stabilizers do not undergo any visible phase separation.

The preferred long chain fatty acid metal salts are those disclosed in the above mentioned application 8 a 7 7 4 A 7J&7 No. #092, which is incorporated herein by reference.

Suitable fatty acid metal salts are the higher aliphatic fatty acid metal salts having from about 8 to about 22 carbon atoms, more preferably from about 10 to 20 carbon atoms, and especially preferably from about 12 to 18 carbon atoms, inclusive of the carbon atom of the carboxyl group of the fatty acid. The aliphatic radical may be saturated or unsaturated and may be straight or branched.

Straight chain saturated fatty acids are preferred.

Mixtures of fatty acids may be used, such as those derived from natural sources, such as tallow fatty acid, coco fatty acid, soya fatty acid, etc., or from synthetic sources available from industrial manufacturing processes.

Thus, examples of the fatty acids from which the polyvalent metal salt stabilizers can be formed include, for example, decanoic acid, dodecanoic acid, palmitic o acid, myristic acid, itearic acid, oleic acid, eicosanoic 0 acid, tallow fatty acid, coco fatty acid, soya fatty acid, mixtures of these acids, etc. Stearic acid and mixed '30 fatty acids are preferred.

The preferred metals are the polyvalent metals, such as magnesium, calcium, aluminum and zinc.

oi. 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 -24tristearate, Al(C 7 H 3 5 CO) 3 The monoacid salts, e.g. aluminum monostearate, A1(OH) 2 (C 1

H

35 COO) and diacid satls, e.g. aluminum distearate, A1(OH)C 1 7

H

35

COO)

2 and mixtures of two or three of the mono-, di- and tri- acid salts can be used for those metals, e.g. Al, with valences of and mixtures of the mono-and di-acid salts can be used for those metals. e.g.

Zn, with valences of +2.

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.

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 fatty acids as the stabilizing agent are of particular advantage because of their known low toxicity. For this purpose, the calcium stearate, i.e. calcium distrearate, magnesium stearate, i.e.

magnesium distearate are especially preferred as generally safe food additives.

The amount of the fatty acid metal salt stabilizers to achieve the desired enhancement of physical stability will depend on such factors as the nature of the fatty 0 acid salt, the nature and amount of the thixotropic agent, S detergent active compound, inorganic salts, especially S" 30 TPP, other LADD ingredients, as well as the anticipated storage and shipping conditions.

Generally, however, amounts of the fatty acid metal S salt stabilizing agents in the range of from about 0.2 to preferably from about 0.5 to especially preferably from about 0.5 to provide the long term 25 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.

Depending on the amounts, proportions and types of physical stabilizers and thixotropic agents, the addition of the fatty acid metal salt not only increases physical stability but also provides a simultaneous increase in apparent viscosity. Ratios of fatty acid to thixotropic agent in the range of from about 0.08 to 0.4 weight percent fatty acid and from about 1.3 to 2.5 weight percent thixotropic agent are usually sufficient to provide these simultaneous benefits and, therefore, the use of these ingredients in these ratios is most preferred.

According to one method of making these compositions, one should dissolve or disperse first all the inorganic salts, i.e carbonate (when employed), silicate and tripolyphosphate, in the aqueous medium. Thickening agent (when employed) is added just before the stabilized enzyme system. The foam depressor (when employed) is preliminarily provided as an aqueous dispersion, as is the thickening 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. Surfactant, fatty acid stabilizer and thickener dispersion at room temperature are thereafter added to the cooled (25-25 0 C) solution. The stabilized enzyme system of the present invention is added last. The total salt concentration (NaTPP, sodium silicate and carbonate) is generally about 20 to 50 weight percent, preferably about 30 to 40 weight percent in the composition. The stabilized enzyme system is generally 6 6 about 15 to 25 parts by weight, preferably about 15 to parts by weight of the composition.

Another method for mixing the ingredients of the LADD B~TIIP=rP~ r: 1 0 26 formulations involves first forming a mixture of the water, foam suppressor (when employed), detergent, physical stabilizer, e.g. fatty acid, (when employed) and thixotropic agent, e.g. clay, (when employed). 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 have been obtained by adding the remaining ingredients in the following sequence: sodium hydroxide, alkali metal carbonate, sodium silicate, alkali o metal tripolyphosphate (hydrated), alkali metal tripolyphosphate (anhydrous or up to 5% water), sodium hydroxide and the stabilized enzyme system last.

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 pigements and the like, all of course being stable to high alkalinity (properties of all the components.) Especially preferred for colouring are the chlorinated *oo phthalocyanines and polysulphides of aluminosilicate which provide, respectively, pleasing green and blue tints.

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

27 The liquid ADD compositions of this invention are readily employed in known manner for washing dishes, 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 aqueous thixotropic clay 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 stabilized enzyme system will apply equally well to aqueous liquid dishwasher compositions and powder dishwasher compositions.

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 120 weight of the composition unless otherwise indicated.

Example 1 A stabilized enzyme system was prepared in accordance with the present invention using the following procedure.

12.6 grams of sodium borate (Na 3

BO

3 was added to 56.1 grams of tartaric acid in 90 grams of water with stirring. The mixture was neutralized to about pH 7 with 56.1 grams NaOH (50% solution).

60 grams of casein, supplied by Bridel, were added to 270 grams of water containing 1.8 grams NaOH, 130 under stirring and heating. After complete dissolution, grams Esperase 8.OL were added at 50 0 C, and 9 grams Termamyl 120L were added at room temperature to obtain a casein enzyme mixture.

S. The mixture obtained in steps and above are mixed together to obtain the premixed stabilized lg 28 enzyme system of the present invention.

The entire premixed stabilized enzyme system, i.e.

about 570.6 grams, can be incorporated in an aqueous liquid dishwasher composition or in an aqueous liquid thixotropic clay dishwasher composition to obtain about 3000g of dishwasher composition in which the stabilized enzyme system of the present invention is present in the following amounts.

Weight Percent Na 3 B03 0.4 Tartaric Acid 1.9 Casein Esperase 8.0L Termamyl 120L 0.3 Dishwasher compositions containing the stabilized enzyme system of the present invention are found to efficiently clean dirty dishes even in the absence of compounds that supply active chlorine.

Example 2 A stabilized enzyme system was prepared following the procedure of Example 1 containing the following ingredients.

Parts byWeight Na 2

B

4 07 10H 2 0 0.8 Citric Acid 2.6 Casein Esperase 8.0L Termamyl 0.3 A thixotropic clay dishwasher detergent composition was prepared and about 19 parts by weight of the above stabilized enzyme system were added to about 81 parts by D~I-rsa 29 weight of a dishwasher detergent composition to obtain the following dishwasher detergent composition.

Weight Percent Deionized Water 43.7 Caustic Soda Solution 2.2 Sodium Carbonate (anhydrous) Sodium Silicate (47.5% solution of Na 2 O:SiO z ratio 1:2.4) 15.74 Sodium TPP (substantially anhydrous, i.e. preferably 3% moisture) (Thermphos NW) 12.0 Sodium TPP (hexahydrate) (Thermphos N hexa) 12.0 Na 2

B

4 07 10H 2 0 0.8 Citric Acid 2.6 Casein Esperase 8.0L Termamyl 120L 0.3 Monostearyl Phosphate 0.16 DOWFAX 3B-2 (45% Na monodecyl/ didecyl diphenyl oxide disulphonate aqueous solution) 0.80 Aluminum Stearate 0.20 Pharmagel H (Thixotropic Clay) 100.00 i Example 3 The aqueous liquid thixotropic dishwasher composition of Example 2 containing the stabilized enzyme system of the present invention comprising 0.5 weight percent Esperase 8.0L and 0.3 weight percent Termamyl 120L enzymes was tested for proteolytic activity and for amylolytic activity after ageing at 4 0 C, room temperature and 35 0 C, for 1, 4 and 8 weeks. The dishwasher detergent C ~1191 1 30 composition had an about pH 11.7. The results obtained are reported in the following table.

Ageing Temperature 4 0 C Room Temp. 35 0

C

Ageing Time (Weeks) 1 2 4 1 2 4 1 2 4 Proteolytic Activity 77 58 51 38 32 Amylolytic Activity 50 22 4 The borax-citric acid and casein-Esperase and Termamyl stabilized enzyme system of the present invention not only allows a stabilization of amylase under very detrimental conditions (amylase is normally destroyed at pH9) but also allows an observed amylolytic activity at highly alkaline pH. The dishwasher detergent composition in fact exhibited an amyloltic activity in dishwasher composition after months storage at room temperature.

On further testing it was found that the efficiency of o the above formulation on hard wastes was higher than for any S market ADD, especially at low dishwashing machine .o o concentration of Example 4 -o So In accordance with the present invention an aqueous 25 liquid dishwasher detergent composition was prepared which is suitable for handwashing dishes and for presoaking especially dirty dishes prior to machine washing. The composition has o o the following ingredients in the amount indicated.

oo i 00' -0 i rr Hi" 31 Weight Percent Deionized Water 46.1 Caustic Soda Solution 2.2 Sodium Carbonate (anhydrous) Sodium Silicate (47.5% solution of Na20:SiO 2 ratio 1:2.4) 15.74 Sodium TPP (Thermphos NW) 12.0 Sodium TPP (Thermphos N hexa) 12.0 Na 2

B

4 0 7 10H 2 0 0.9 Lactic Acid 1.8 Casein Esperase 8.0L 0.8 Monostearyl Phosphate 0.16 DOWFAX 3B-2 (45% Na monodecyl/ didecyl diphenyl oxide disulphonate aqueous solution) 0.80 Aluminum Stearate 0.50 100.00 o The dishwasher detergent compositions of the present Sinvention containing a stabilized enzyme system can also be formulated as powder dishwasher compositions.

In the above formulating procedure the ingredients and the proportions thereof can be varied by those skilled in the art to obtain desired dishwasher detergent o, compositions of specific ingredients and proportions.

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.

I

Claims (4)

1. An aqueous liquid dishwasher composition containing a stabilized enzyme system which composition comprises: water an alkali metal phosphate builder salt, an organic surfactant, a boron compound, an alpha-hydroxy carboxylic acid, casein, and an enzyme.

2. The aqueous liquid dishwasher composition of claim 1 o wherein said boron compound is at least one of borax o (Na 2 B 4 0 7 .10H 2 sodium borate (Na 3 BO 3 oooboric acid and boric oxide. .oo. o1 3. An aqueous liquid dishwasher composition containing a stabilized enzyme system which composition comprises: Weight By Percent Water

35-65% Alkali Metal Phosphate Builder Salt 8-35 Sodium Silicate 0-20 An Organic Surfactant Boron Compound 0.4-2 Alpha-hydroxy Carboxylic Acid Casein 1-6 Enzyme 1-6. 4. The aqueous liquid dishwasher composition of claim 3 o0 comprising 0 to 5% by weight of a thixotropic clay thickener. OO p C u 5. The aqueous liquid dishwasher composition of claim 3 wherein said boron compound is at least one of borax (Na 2 B 4 0 7 .10H 2 sodium borate (Na 3 BO 3 boric acid and boric oxide. 6. The aqueous liquid dishwasher composition of claim 3 comprising I' -1 i.irSB~ll~IRIII 33 u o o Weight By Percent Water 40-55 Sodium Tripolyphosphate (TPP) 20-30 An Organic Surfactant Sodium Silicate 0-20 Sodium Carbonate 0-9 Anti-foam Agent Borax (Na 2 B 4 07 .10H 2 0) C.75 to Alpha-Hydroxy Carboxlic Acid 1.5 to Casein 1.0 to Enzyme 0.5 to 7. The aqueous liquid dishwasher composition of claim 6 wherein the anionic surfactant is sodium linear tridecylbenzene. 8. The aqueous liquid dishwasher composition of claim 6 wherein the alpha-hydroxy carboxylic acid is at least one of lactic acid, tartaric acid, citric acid and the sodium salts thereof. 9. The aqueous liquid dishwasher composition of claim 6 wherein the alpha-hydroxy carboxylic acid comprises citric acid and the sodium thereof. The aqueous liquid dishwasher composition of claim 3 comprising o 0 r o r. er o I r Water Sodium Tripolyphosphate Thixotropic Clay Thickener Anionic Surfactant Sodium Silicate Sodium Carbonate Anti-foam Agent Borax (Na 2 Ba407.10H20) Alpha-Hydroxy Carboxlic Acid Casein Enzyme Weight By Percent

40-55 20-30 0.25-5.0 0.1-5 0-20 2-9 0.1-0.5 0.75 to 1.5 to 1.0 to 0.5 to 34 11. The aqueous liquid dishwasher detergent composition of claim 10 wherein the anionic surfactant is sodium linear decyl sulfonate. 12. The aqueous liquid dishwasher detergent composition of claim 10 wherein the alpha-hydroxy carboxylic acid is at least one of lactic acid, tartaric acid, citric acid and the sodium salts thereof. 13. An aqueous thixotropic automatic dishwasher composition containing a stabilized enzyme system which composition comprises: Weight By Percent Water 40-55 Sodium Tripolyphosphate 20-30 Thixotropic Clay Thickener 0.5 to Sodium Silicate 2.5-20 Sodium Carbonate 2-9 Anionic Surfactant 0.3-2.0 Borax (Na 2 B 4 0 7 10H 2 0) 0.75 to Alpha-Hydroxy Carboxylic Acid 1.5 to Casein 1.0 to Enzyme 0.5 to 14. The aqueous thixotropic automatic dishwasher composition of claim 13 containing a long chain fatty acid metal salt physical stabilizing agent in an amount sufficient to increase the physical stability of the composition. The composition of claim 14 wherein the physical stabilizing agent is aluminium stearate. 16. The composition of claim 14 wherein the physical stabilizing agent is present in an amount of about 0.1-2. 17. The composition of claim 13 wherein the thixotropic thickener is an inorganic or organic, colloid-forming clay. 18. The composition of claim 13 wherein the clay is a montmorillonite clay, an attapulgite clay, a hectorite clay or a smectite clay. 35 19. The composition of claim 13 contain 0.1 to 0.5 of an anti-foam agent. A method for cleaning soiled dishware which comprises contacting the soiled dishware with the aqueous liquid dishwasher composition of claim 1. 21. A method for cleaning soiled dishware in an automatic dishwashing machine which comprises contacting the soiled dishware in an automatic dishwashing machine containing an aqueous washbath having dispersed therein an effective amount of the composition of claim 6. 22. A method for cleaning soiled dishware in an automatic dishwashing machine which comprises contacting the soiled dishware in an automatic dishwashing machine containing an aqueous washbath having dispersed therein an effective amount of the composition of claim 13. DATED this 12th day of February 1991 COLGATE-PALMOLIVE COMPANY Patent Attorneys for the Applicant: F.B. RICE CO.