GB2208869A - Thixotropic liquid compositions - Google Patents

Description

1 1 THIXOTROPIC LIQUID COMPOSITIONS 2208869 The present invention relates

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

The present invention relates in preferred embodiments to automatic dishwashing detergent compositions having thixotropic properties, improved chemical and physical stability, 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.

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

Recent research and development activity has focussed on the gel or "thixotropic" form of such compositions, e.g. scouring cleansers and automaticdishwasher products characterised as thixotropic pastes. Dishwasher products so provided are primarily objectionable in that they are insufficiently viscous to remain Hanchored" in the dispenser cup of the dishwasher, and moreover yield spotty residues on dishware, glassware, china and the like. Ideally, thixotropic 1 2 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.

GB-A-2176495 is directed to thixotropic clay aqueous suspension dishwashing detergent compositions containing polyvalent metal salts of long chain fatty acids, such as aluminium stearate as physical stabilizing agents. The compositions of GB-A-2176495 show improvement in the physical stability of the detergent composition and improvement against phase separation over those clay containing compositions that do not contain the aluminium stearate.

The provision of automatic-dishwasher compositions in gel form having the aforedescribed properties, other than for the improvements described in the above mentioned application GB-A-2176495 has thus far proven problematical, particularly as regards compositions for use in home dishwasher machines. For effective use, it is generally recommended that the automatic dishwashing detergent, hereinafter also designated ADD, contain (1) sodium tripolyphosphate (NaTPP) to soften or tie up hard-water minerals and to emulsify and/or peptize soil; (2) sodium silicate to supply the alkalinity necessary for effective detergency and to provide protection for fine china glaze and pattern; (3) sodium 4 3 carbonate, generally considered to be optional, to enhance alkalinity; (4) a chlorine-releasing agent to aid in the elimination of soil specks which lead to water spotting; and (5) defoamer/ surfactant to reduce foam, thereby enhancing machine efficiency and supplying requisite detergency. See, for example, SDA Detergents in Depth, "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, US-A-4115308 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. US-A-4147650 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.

US-A-3985668 describes abrasive scouring cleaners of gel-like consistency containing (1) suspending agent, referably the Smectite and attapulgite types of clay; (2) abrasive, e.g. silica sand or perlite; and (3) filler comprising light density powdered polymers, expanded perlite and the like, which has a 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 4 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 optional ingredients to supply or supplement building function not provided by the buffer, the amount of such builder not exceeding 5% of the total composition, according to the patent.

Maintenance of the desired (greater than) pH 10 levels is achieved by the buffer/ builder components. High pH is said to minimize decomposition of chlorine bleach and undesired interaction between surfactant and bleach. Foam killer is not disclosed.

In GB-A-2116199 and GB-A-2140450, liquid ADD compositions are disclosed which have properties desirably characterising thixotropic, gel-type structure and which include each of the various ingredients necessary for effective detergency with an automatic dishwasher. The normally gel-like aqueous automatic dishwasher detergent composition having thixotropic properties include the following ingredients, on a weight basis:

(a) 5 to 35% alkali metal tripolyphosphate; (b) 2.5 to 20% sodium silicate; (c) 0 to 9% alkali metal carbonate; (d) 0.1 to 5% chlorine bleach stable, water dispersible organic detergent active material; (e) 0 to 5% chlorine bleach stable foam depressant; (f) chlorine bleach compound in an amount to provide about 0.2 to 4% of available chlorine; (g) thixotropic thickener in an amount sufficient to provide the composition with thixotropy index of about 2.5 to 10; (h) sodium hydroxide, as necessary, to adjust pH; and balance water.

ADD compositions so formulated are low-foaming; are readily soluble in the washing medium and most effective at pH values best conducive to improved cleaning performance, viz. pH 10.5-14. The composi- tions are normally of gel consistency, i.e. a highly viscous, opaque jelly-like material having Bingham plastic character and thus relatively high yield values. Accordingly, a definite shear force is necessary to initiate or increase flow, such as would obtain within the agitated dispenser cup of an energized automatic dishwasher. Under such conditions, the composition is quickly fluidized and easily dispersed. When the shear force is discontinued, the fluid composition quickly reverts to a high viscosity, Bingham plastic state closely approximating its prior consistency.

US-A-4511487 describes a low-foaming detergent paste for dishwashers. The thixotropic cleaning agent disclosed has a viscosity of at least 30 Pa.s at 200C 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 foliated silicate of the hectorite type. Small amount of nonionic tensides and alkali metal carbonates and/or hydroxides may be used.

The formation of organoclays by the interaction of clays (such as bentonite and hectorite) with organic 6 compounds such as quaternary ammonium salts, has also been described (W.S. Mardis, JAMS, Vol. 61, No. 2, p.382 (1984)).

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

While the combination of clay thickener and polyvalent metal fatty acid salt stabilizer disclosed in the above mentioned GB-A-2176495 has been found to provide satisfactory long term stability, such as absence of phase separation for periods of up to 12 weeks and longer, it is desirable to further improve the stability so as to avoid phase separation for up to six months or more.

Further, the use of the known stabilizers, e.g.

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

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

Accordingly, the present invention enables the provision of anti-settling additives for thixotropic clay aqueous suspensions.

The invention also enables the provision of liquid 7 ADD compositions having thixotropic properties with improved physical stability and rheological properties at lower costs by using polycarboxylic acids and metal salts thereof in place of the more expensive polyvalent metal salts of fatty acids.

The invention further enables the provision of thixotropic liquid ADD compositions having reduced levels of thixotropic thickener without adversely effecting the generally high viscosities at low shear rates and lower viscosities at high shear rates which are characteristic of the desired thixotropic properties.

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

Unlike the polyvalent metal long chain fatty acid salts the polycarboxylic acid and metal salts thereof of the present invention can be easily incorporated in the product, e.g. either by emulsifying them with the surfactants or by directly adding them to the batch. The process conditions for formulating the composition are not critical. The polycarboxylic acids and the metal salts thereof are easily dispersed in the composition. The addition of the polycarboxylic acids and metal salts thereof allows reduction of the amount of clay that would be required in the absence of the polycarboxylic acids and metal salts thereof. Further, i 8 the rheological properties of the product can be f ine tuned by adjusting the amount of the polycarboxylic acids and metal salts thereof added to the composition.

These and other objects of the invention which will become more readily understood from the following detailed description of the invention and preferred embodiments thereof are achieved by incorporating in a normally gel-like aqueous liquid composition a small but effective amount of a physical stabilizer which is a polycarboxylic acid or a metal or ammonium salt thereof. More particularly, according to a preferred and specific embodiment of the invention, there is provided a normally gel-like automatic dishwasher detergent composition in which is incorporated an amount of polycarboxylic acids and metal salt thereof which is effective to increase the apparent viscosity of the formulation and to inhibit settling of the suspended particles, such as detergent builder and thixotropic clay agent. 20 In accordance with a preferred feature of this particular aspect, the present invention provides a normally gel-like aqueous automatic dishwasher detergent composition having thixotropic properties which include, on a weight basis: 25 (a) 5 to 35% alkali metal tripolyphosphate; (b) 2.5 to 20% sodium silicate; (c) 0 to 9% alkali metal carbonate; (d) 0.1 to 5% chlorine bleach stable, water dispersible organic detergent active material; 30 (e) 0 to 5% chlorine bleach stable foam depressant; (f) chlorine bleach compound in an amount to provide about 0.2 to 4% of available chlorine; 9 (g) thixotropic thickener in an amount sufficient to provide the composition with thixotropy index of about 2.5 to 10; and (h) 0 to 8% sodium hydroxide; one or more polycarboxylic acids and/or inetal and/or ammonium salts thereof in an amount effective to increase apparent viscosity and the physical stability of the composition; and (j) balance water.

Also related to this specific aspect, the invention provides a method for cleaning dishware in an automatic dishwashing machine with an aqueous wash bath containing an effective amount of the liquid automatic dishwasher detergent (LADD) composition as described above. Accordingly 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 to remain securely within the dispensing cup until shear forces are again applied thereto, such as by the water spray from the dishwashing machine.

The present invention is based upon the surprising and unexpected discovery that the same or improved rheological properties and physical stability, i.e. resistance to phase separation, settling, etc., as in the prior liquid aqueous ADD compositions can be achieved, at lower cost and without any particular processing requirements, by adding to the composition an effective stabilizing amount of polycarboxylic acids and metal salts thereof in place of the polyvalent metal fatty acid salt. At the same time, improvements in spotting and filming performance (i.e. fewer spots and reduced filming) can be achieved. Amazingly, formulations prepared with, for example, 0. 03 to 0. 2% of the polycarboxylic acids and metal salts thereof have excellent rheological properties and have been stable in storage for up to six months.

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

The NaTPP employed in the LADD composition in a range of about 8 to 35 wt%, preferably about 20 to 30 wt%, should preferably be free of heavy metal which tends to decompose or inactivate the preferred sodium hypochlorite and other chlorine bleach compounds. The NaTPP may be anhydrous or hydrated, including the stable hexahydrate with a degree of hydration of 6 corresponding to about 18% by weight of water or more.

11 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 dish,aasher machine efficiency and minimize destabilizing effects which might occur due to the presence of excess foam within the washer during use. Foam may be sufficiently reduced by suitable selection of the type and/or amount of detergent active material, the main foam-producing component. The degree of foam is also somewhat dependent on the hardness of the wash water in the machine whereby suitable adjustment of the proportions of NaTPP which has a water softening effect may aid in providing the desired degree of foam inhibition. However, there may optimally be included a chlorine bleach stable foam depressant or inhibitor where a low foam LADD is desired. Particularly effective are the alkyl phosphonic acid esters of the formula 1 12 0 is HO---P-R OR available for-example from BASP-Wyandotte (PCUK-PAE), and especially the alkyl acid phosphate esters of the formula 0 It HO--P--OR I 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 C12-20 alkyl group. Mixtures of the two types, or any other chlorine bleach stable types, or mixtures of mono- and diesters of the same type, may be employed.

Especially preferred is a mixture of mono- and di-C16,a alkyl acid phosphate esters such as monostearyl/distearyl acid phosphates 1.2/1 (Knapsack) or 4/1 (UGINE KULHPLAN). When employed, proportions of 0.1 to 5 wt%, preferably about 0.1 to 0.5 wt%, of foam depressant in the composition is typical, the weight ratio of detergent active component (d) to foam depressant (e) generaliy ranging from about 10:1 to 1:1 and preferably about 5: 1 to 1: 1. Other defoamers which may be used include, for example, the known silicones. In addition, it is an advantageous feature of this invention that many of the stabilizing polycarboxylic acids and metal salts thereof act as foam killers.

Although any chlorine bleach compound may be 13 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 4.0% by weight of sodium hypochlorite contains or provides roughly the same percentage of available chlorine. About 0.8 to 1.6% by weight of available chlorine is especially preferred. For example, sodium hypochlorite (NaOCl) solution of from about 11 to about 14% available chlorine in amounts of about 3 to 20%, preferably about 7 to 12% by weight, can be advantageously used.

The sodium silicate, which provides alkalinity and protection of hard surfaces, such as fine china glaze and pattern, is employed in an amount ranging from about 2.5 to 20 wt%, preferably about 5 to 15 wt%, in the composition. The sodium silicate is generally added in the form of an aqueous solution, preferably having an Na2o:S'02 ratio of about 1:2 to 1:2.8.

Detergent active material useful herein should for preference 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 generally used in amounts ranging from about 0.1 to 5%, preferably about 0.3 to 2.0%. Particularly preferred surfactants herein are 1 14 the linear or branched alkali metal mono- and/or di(%-14) alkyl diphenyl oxide mono and/or disulphates or disulphonates, commercially available for example as DOWFAX (Registered Trademark) 3B-2 and DOWFAX 2A-1. In addition, the surfactant should be compatible with the other ingredients of the composition. other suitable sur;Eactants include the primary alkylsulphates, alkylsulphonates, alkylaryl-sulphonates such as sodium dodecylsulphate and sodium tallow alcohol sulphate; sodium C10-C18 alkanesulphonates such as sodium hexadecyl-l-sulphonate and sodium C12- CI8 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 R2R1N-0, in which each R represents a lower alkyl group, for instance, methyl, and R' represents a long chain alkyl group having from 8 to 22 carbon atoms, for instance a lauryl, myristyl, palmityl or cetyl group. Instead of an amine oxide, a corresponding surfactant phosphine oxide R2R1P0 or sulphoxide RR'SO can be employed. Betaine surfactants are typically of the structure R2R1N-RfCOO-1 in which each R represents a lower alkylene group having from 1 to 5 carbon atoms. Specific examples of these surfactants are lauryldimethylanine oxide, myristyldimethylamine oxide, the corresponding phosphine oxides and sulphoxides, and the corresponding betaines, including dodecyldimethylammon- ium acetate, tetradecyld iethyl ammonium pentanoate, hexadecyldimethylammonium hexanoate and the like. For biodegradability, the alkyl groups in these surfactants should be linear, and such compounds are preferred.

1 Surf actants of the foregoing type, all well known in the art, are described, for example, in US-A-3985668 and US-A-4271030.

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

stable to high alkalinity and chlorine bleach compounds, such as sodium hypochlorite. Those especially preferred generally comprise the inorganic, colloid-forming clays of smectite and/or attapulgite types. These materials were generally used in amounts of about 1.0 to 10, preferably 1.2 to 5 wt%, to confer the desired thixotropic properties and Bingham plastic character in the assignee's prior disclosed LADD formulations of the aforementioned GB-A-2116199 and GBA-2140450. 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 polycarboxylic acids and metal salts thereof stabilizers with lesser amounts of the thixotropic thickeners. For example, amounts of the inorganic colloid-forming clays of the smectite and/or attapulgite types in the range of from about 0.1 to 3%, preferably 0.1 to 2.5%, especially 0.1 to 2%, are generally sufficient to achieve the desired thixotropic properties and Bingham plastic character when used in combination with the physical stabilizer.

Smectite clays include montmorillonite (bentonite), hectorite, attapulgite, smectite, saponite, and the like. Montmbrillonite clays are 16 preferred and are available under tradenames such as THIXOGEL (Registered Trademark) No. 1 and GELWHITE (Registered Trademark) GP, H, etc., from Georgia Kaolin Company; and ECCAGUM (Registered Trademark) GP, H, etc.,, from Luthern Clay Products. Attapulgite clays include the materials commercially available uhder the tradename ATTAGEL (Registered Trademark), i.e. ATTAGEL 40, ATTAGEL 50 and ATTAGEL 150 from Engelhard Minerals and Chemicals Corporation. Mixtures of smectite and attapulgite types in weight ratios of 4:1 to 1:5 are also useful herein. Thickening or suspending agents of the foregoing types are well known in the art, being described, for example, in US-A-3985668 referred to above. Abrasives or polishing agents should for preference be avoided in the LADD compositions as they may mar the surface of fine dishware, crystal and the like.

The amount of water contained in these compositions should, of course, be neither so high as to produce unduly low viscosity and fluidity, nor so low as to produce unduly high viscosity and low flowability, thixotropic properties in either case being diminished or destroyed. Such amount is readily determined by routine experimentation in any particular instance, generally ranging from about 30 to 75 wt%, preferably' about 35 to 65 wt% and more preferably from about 3 to 45%. 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 GB-A-2116199 and GBA-2140450.

The LADD products of GB-A-2116199 and GB-A- 17 2140450 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 extent within the standard dish-washer machine. In practical terms, this means improved pouring and processing characteristics as well as less leaking in the machine dispenser-cup, compared to prior liquid or gel ADD products. For applied shear rates corresponding to 3 to 30 rpm, viscosities (Brookfield) correspondingly ranged from about 10,000 to 30,000 cps to about 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 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 these prior applications thus exhibit threshold fluidizations at lower shear rates and of significantly greater extent in terms of incremental increas6s 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 18 quiescent state consistency when the shear f orce was discontinued.

The present invention is based upon the discovery that the physical stability, i. e. resistance to phase separation, settling, etc., of the liquid aqueous ADD compositions df GB-A-2116199, GB-A-2140450 and GBA2176495 can be significantly improved or not adversely affected while at the same time significantly increasing the apparent viscosity and improving the physical stability of the formulations and at lower cost, by adding to the composition a small but effective amount of polycarboxylic acids and metal salts thereof.

As an example of the improvement in rheological properties, it has been found that the viscosities at low shear rate, e.g. at a spindle rpm of about 3, apparent viscosities may often be increased from twoto three-fold with the incorporation of as little as 0.2% or less, e.g. 0.15%, of the polycarboxylic acids and metal salts thereof stabilizers. At the same time, the physical stability may be improved to such an extent that even after a long time, e.g. 6 months aging at 200C (RT), the compositions containing the polycarboxylic acids and metal salts thereof stabilizers do not undergo any visible phase separation.

The physical stabilizing agents that are used in accordance with the present invention are polycarboxylic acids and the metal and ammonium salts thereof; the stabilizers may be low molecular weight carboxylic acids and the monovalent metal and polyvalent metal salts thereof. The polycarboxylic acids that can be used in accordance with the present

invention include the Z 19 diners and trimers of fatty acids, preferably the unsaturated fatty acids. The C8 to C22 fatty acids can be used. The diners and trimers are preferably prepared from the C12-C20 fatty acids and more preferably from the C16-C20 unsaturated fatty acids. The most preferred dimer and trimer acids are prepared from C,8 unsaturated fatty acids, e.g. oleic acid and linoleic acid.

The monovalent metal salts and the polyvalent 10 metal salts of the diners and trimers of the fatty acids, preferably the unsaturated fatty acids, can also be used in the present invention. The ammonium salts of the diners and trimers of the unsaturated fatty acids can also be used in the present invention.

is A particular preferred group of polycarboxylic acids are the diners and trimers of C,8 unsaturated fatty acids that are available from Emery Industries, Division of National Distillers & Chemical Corp. These materials are available under the following trade names:

Diners EMPOL 1010 EMPOL 1018 EMPOL 1022 EMPOL 1024 Trimers Polybasic Acid EMPOL 1040 EMPOL 1052 EMPOL 1041 The EMPOL 1040 and EMPOL 1052 are of particular interest. The EMPOL 1040 Trimer Acid typically contains 80% polybasic acids, 18% dibasic acid and 2% monobasic acid. The EMPOL 1052 Polybasic Acid contains 63% tribasic, tetrabasic and higher acids with about 34% dibasic acid.

In addition to the diner and trimer acids, the adipic and azelaic polycarboxylic acids and their mono metal and ammonium salts and polyvalent metal salts can also be used as stabilizing agents in the present invention.

The monovalent metal salts that can be used include the Group IA metals of the Periodic Table of the Elements, and in particular the alkali metal salts. The Group IA monovalent metals that are included are Li, Na, K, Rb, Cs and Fr. The preferred monovalent alkali metals are Na and K.

There may also be used as an alkali metal the NH4 ammonium cation. The chlorine bleach compounds are, however, not to be used with the ammonium fatty acid salt stabilizers, since they are not compatible with chlorine bledch compounds. In the formulations in which the ammonium fatty acid stabilizers are used, the chlorine bleach can be omitted or an oxydizing enzyme can be substituted for the chlorine bleach.

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

There can also be used in the formulations of the present' invention proteolytic and amylolytic enzymes and mixtures thereof. The proteolytic enzymes suitable for use include liquid, powder or slurry enzyme preparations. Suitable liquid enzyme preparations include ALCALASE and ESPERASE sold by Novo Industrie, Copenhagen, Denmark. Liquid protease and liquid axylase enzymes can be used. Suitable alpha-amylase 4 21 liquid enzyme preparations are those sold by Novo Industries and Gist- Brocades under the trade names TERMANYL and MAXAMYL, respectively.

The enzymes can be used in amounts of about 0.5 to 3%, preferably about 0. 5 to 2.0% and more preferably bibout 0.5 to 1.5%.

The preferred polyvalent metals are the polyvalent metals of Groups IIA, IIB and IIIB, such as magnesium, calcium, aluminium and zinc, although other polyvalent metals, including those of Groups IIIA, IVA, VA, VIA, VIIA, IB, I'JB, VB, VIB, VIIB and VIII of the Periodic Table of the Elements can also be used. Specif ic 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.

Naturally, for LADD compositions, as well as any other applications where compositions in accordance with the invention will or may come into contact with articles used for the handling, storage or serving of food products or which otherwise may come into contact with or be consumed by people or animals, the use of the polycarboxylic acids and metal salts thereof as the stabilizing agent are of particular advantage because of their known low toxicity. For this purpose, the polycarboxylic acids per se, e.g. dimers and trimers of C18 unsaturated fatty acid, the monovalent Na and K and the NH4 salts and the polyvalent Ca and Mg metal salts thereof are especially preferred as generally safe because of their known low toxicity and/or known use as food additives. Another distinct advantage of the use of the polycarboxylic acids and metal salts thereof as stabilizers is their lower cost as compared to the polyvalent fatty acid metal salts.

Many of the polycarboxylic acids and metal salts thereof are commercially available. For example, the dimers and trimers of the C,8 unsaturated fatty acids, and adipic and azelaic acids are readily available.

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

Generally, however, amounts of the polycarboxylic acids and metal salts thereof stabilizing agents in the range of from about 0.601 to 1.0, preferably from about 0.01 to 0.2%, especially preferably from about 0.05 to 0.2%, provide the increase in apparent viscosity and the long term stability and absence of phase separation upon standing or during transport at both low and elevated temperatures as are required for a commercially acceptable product.

From the examples to be given below, it will be seen that, depending on the amounts, proportions and types of physical stabilizers and thixotropic agents, the addition of the polycarboxylic acids and metal salts thereof not only increases physical stability but also provides a simultaneous increase in apparent viscosity.

The method of formulating the compositions is not critical, but by way of example three illustrative methods are given.

1. 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 is added last. 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 tempera- tures in aqueous solution (deionized water) and, thereafter, cooled, using agitation throughout. Bleach, surfactant, polycarboxylic acid and metal salt thereof stabilizer and thickener dispersion at room temperature are thereafter added to the cooled (25-35OC) solution.

Excluding the chlorine bleach compound, 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.

2. A preferred method for mixing the ingredients Of the LADD formulations involves first forming a mixture of the water, foam suppressor (when employed), detergent, polycarboxylic acid and metal salt thereof physical stabilizer (fatty acid) and thixotropic agent, 24 e. g. clay. These ingredients are mixed together under high shear conditions, preferably starting at room temperature, to form a uniform dispersion. To this premixed portion, the remaining ingredients are introduced under low shear mixing conditions. For instance, the"required amount of the premix is introduced into a low shear mixer and thereafter the remaining ingredients are added, with mixing, either sequentially or simultaneously. Preferably, the ingredients are added sequentially, although it is not necessary to complete the addition of all of one ingredient before beginning to add the next ingredient. Furthermore, one or more of the ingredients can be divided into portions and added at different times. Good results have been obtained by adding the remaining ingredients in the following sequence: sodium hydroxide, alkali metal carbonate, sodium silicate, alkali metal tripolyphosphate (hydrated), alkali metal tripolyphosphate (anhydrous or up to 5% water), bleach (preferably, sodium hypochlorite) and sodium hydroxide.

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

Weight 35-45 1-3 0.2-4 0.01 to 0.2 Deionized water Colour Clay Polycarboxylic Acid or Metal or Ammonium Salt Thereof Stabilizer Organic Detergent Active Material Anti-foam Agent NaOH 0.1-5 0.1-5 0.5-6 Sodium Carbonate (Soda Ash) 2-9 Sodium Silicate 5-15 Sodium Tripolyphosphate 20-30 Sodium Hypochlorite (13% available chlorine) 0.2-4 The particular order of adding the ingredients is not critical.

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

Other conventional ingredients may be included in these compositions in small amounts, generally less than about 3 weight percent, such as perfume, hydrotropic agents such as the sodium benzene, toluene, xylene and cumene sulphonates, preservatives, dyestuffs and pigments and the like, all of course being stable to chlorine bleach compound and high alkalinity (properties of all the components). In formulations containing an ammonium fatty acid salt stabilizer, enzymes such as glucose oxidase, catalase, lipoxidase, proteolytic and amylolytic enzymes can be used in place of the chlorine bleach. Especially preferred for colouring are the chlorinated phthalocyanines and polysulphides of aluminosilicate which provide, respectively, pleasing green and blue tints. T'02 may be employed for whitening or neutralizing off-shades.

Liquid ADD compositions of this invention are readily employable 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 hn 26 effective amount of the composition.

While the invention has been particularly described in connection with its application to liquid automatic dishwasher detergents it will be readily understood by one of ordinary skill in the art that the benefits which are obtained by the addition of the polycarboxylic acids and metal and ammonium salts thereof, namely increased apparent viscosity and increased physical stability of the clay based thixo- tropic suspension, will apply equally well to other clay based thixotropic suspensions, such as the scouring paste formulations described in the aforementioned Patent US-A-3985668.

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

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

COMPARATIVE EXAMPLES 1 & 2 AND EXAMPLE 1 In order to demonstrate the effect of the polycarboxylic acid stabilizer, a liquid ADD formulation containing a trimer of an unsaturated fatty acid, e.g.

EMPOL 1042 is prepared as follows.

Deionized water Caustic soda solution (50% NaOH) Sodium carbonate, anhydrous Sodium silicate, 47.5 solution of Na20:S'02 ratio of 1:2.4 Sodium TPP (substantially anhydrousi.e. 0-5%, especially 3%, moisture) Percent 41.10 2.20 5.00 15.74 12.00 27 4 (THERMPHOS NW) Sodium TPP (hexahydrate) (THERMPHOS N HEXA) 12.00 The mixture is cooled at 25-300C and agitation maintained throughout, and the following ingredients at room temperature are added thereto:

Percent 9.00 Sodium hypochlorite solution (11% available chlorine) Monostearyl phosphate DOWFAX 3B-2 (45% Na monodecyl/didecyl diphenyl oxide disulphonate-aqueous solution) Physical stabilizer (fatty acid or fatty X 0.16 0.80 acid salt) PHARMAGEL H 2.00 There are three formulations prepared in which X = 0% (Comparative Example 1), X = 0. 10-o aluminium (stearate (Comparative Example 2) and X = 0.2% EMPOL 1040 trimer 20 acid (Example 1). The formulations are adjusted to 100% by adjusting the water content.

The EMPOL 1040 is the trimer of a C18 unsaturated fatty acid and is supplied by Emery Industries, Div. of National Distillers & Chemical Corp.

Th6 monostearyl phosphate foam depressant (when employed) and Dowfax 3B-2 detergent active compound and EMPOL 1040 stabilizer are added to the mixture just 30 before the PHARMAGEL H thickener.

Comparative Example 1 (Run 1) is a control formulation which includes the monostearyl phosphate anti-foam agent, but which does not contain a 28 polycarboxylic acid or metal salt thereof stabilizer.

Comparative Example 2 (Run 2) is a control formulation of Run 1 to which has been added an aluminium stearate stabilizing agent of GB-A-2176495.

Example 1 (Run 3) is a formulation of the present invention in which EXPOL 1040 trimer acid is used as the stabilizing agent.

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

From the data reported in Table 1 the following conclusions are reached:

The incorporation of 0.1% aluminium stearate in a 2% PHARMAGEL H containing formula Run 2 (control) leads to an increase in the apparent viscosity Table, Run 1 (control).

The incorporation of 0.2% EMPOL 1040 trimer acid in a 2% PHARMAGEL H containing formula Run 3 (invention) leads to a significant increase in the apparent viscosity as compared to both the control Runs 1 and 2.

1 29 TABLE 1

RUN FORMULATION BROOK HATD(1) VISCOSITY 20 RPM H20 = 41.10% 1 Monostearyl Phosphate = 0.16% (control) Stabilizer = 05% 40000 PHARMAGEL H = 2.0% H20 = 41.0% 2 Monostearyl Phosphate = 0.16% (control) Al Stearate = 0.1% PHARMAGEL H = 2.0% 8,000 is H20 = 41.0% 3 Monostearyl Phosphate =0.16% (inven- EMPOL 1040 = 0.2% 11,000 tion) PHARMAGEL H = 2.0% (1) Measured with spindle 4 after three minutes at 20 rpm on 24 hour old samples.

EXAMPLES 2A TO 2G AND COMPARISON EXAMPLES 3 TO 6 The following gel-like thixotropic liquid ADD formulation is prepared by simply mixing the ingredients in the order listed.

Weiqht 42.983 0.007 1.000 0.120 0.200 0.800 Deionized Water Colour Clay GLASS HM Sodium Salt of EMPOL 1040 Trimer Acid Dowfax 3B-2 (2) LpKN-1_58(3) Caustic Soda Solution (50% NaOH) Sodium Carbonate (anhydrous) Sodium Silicate, 47.5% solution of 5 Na20:SiO2, ratio 1:2.4 Sodium tri-polyphosphate Sodium Hypochlorite Sol. (11% available chlorine) 0.160 2.400 6.990 13.730 24.000 7.610 100.00 (1) The GLASS H is a linear polyphosphate containing approximately 26 phosphate groups.

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

(3) The LPKN-158 is an anti-foam agent comprising a 2:1 molar mixture of mono-, di- (C16-C18) alkyl esters of phosphoric acid.

In order to compare the stability of the composition, similar formulations were Prepared in which the sodium salt of EMPOL 1040 trimer acid was omitted (Comparison Example 3) or was substituted by aluminium stearate (Comparison Example 4) or stearic acid (Comparison Example 5). The formulations were tested for percentage of formulation settled from solution after standing for six weeks at 1000C and after standing for six months at room temperature (20OC). The results obtained are reported in the following Table 2.

1 31 TABLE 2

Weight Stability Stability Stabili- 6 wks 6 mos zer (100OF) (20OC) No Stabilizer(l) 8.0 7.0 Aluminium Stearate 0.20 0.0 0.0 Stearic Acid 0.20 0.0 0.0 (1) The amount of water was adjusted to 100%.

In order to determine the effect on the amount of 10 clay used in the formulation the above formulation was prepared using 0.2% sodium tartarate and varying the amount of clay present between 0.5 and 2.0%. The results (Examples 2A to 2G and Comparison Example 6) obtained are reported below in Table 3.

TABLE 3

Ex.

Wt.% Wt.% Sodium Stability Stability Cla of Empol 6 wks (100.2n6 mos (20OC) 2A 0.50 0.20 <1.0 <1.0 2B 0.75 0.20 <1.0 <1.0 2C 1.00 0.20 0.0 0.0 2D 1.25 0.20 0.0 0.0 2E 1.50 0.20 0.0 0.0 2F 1.75 0.20 0.0 0.0 2G 2.00 0.20 0.0 0.0 ComP 2.00 -- 8.0 7.0 Ex 6 The amount of water was adjusted to 100%.

The data reported in Table 3 show that by the addition of a small amount of sodium salt of EMPOL 1040 trimer acid, substantially the same or improved results in stability can be obtained using reduced amounts of clay.

32 EXAMPLE 3

The following gel-like thixotropic ADD is prepared by simply mixing the ingredients in the order listed.

Ingredient Amount Wt% Sodium silicate (47.5% solution of Na20:Si02 ratio of 1:2.4) Monostearyl phosphate DOWFAX 3B-2 THERMPHOS NW THERMPHOS N HEXA Calcium salt of EMPOL 1040 Sodium carbonate, anhydrous Caustic soda solution (50% NaOH) PHARMAGEL H Sodium hypochlorite solution (11%) Water 13.74 0.16 0.36 12.0 12.0 0.2 5.0 2.40 1.0 1.0 balance Minor amounts of perfume, colour, etc. can also be added to formulation.

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

EXAMPLE 4

Following the procedure of Example 2, formulations are prepared using the dimers of a C18 unsaturated fatty acid, per se, and K and Na salts of the trimers of a C18 unsaturated fatty acid and Al, Zn, Ca and Mg salts c;f the trimers of a C,8 unsaturated fatty acid and stable formulations having good rheological and thixotropic properties are obtained.

EXAMPLE 5

The procedure of Example 2 is followed and a formulation is prepared in which about 1% of glucose oxidase enzyme is used in place of the hypochloride c 0 4 1, 33 bleach and using the ammonium salt of the trimer of a C18 unsaturated fatty acid as the stabilizing agent.

The formulations are tested and are found to have good rheological and thixotropic properties.

EXAMPLE 6

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

In addition to the superior physical stability, thixotropy and cleaning performance, compositions in accordance with this invention has the addition significant advantage of not requiring any particular order of addition of the respective ingredients. All of the ingredients can be added in any order or simultaneously to a single pot, mixer, etc., and stirred until a uniform homogeneous mixture is obtained. Mixing can be done at room temperature or at elevated temperature. It is not necessary to premix any of the ingredients or to use different shear mixing conditions.

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

34

Claims (1)

1. X 1. An aqueous thixotropic liquid composition comprising water, a thixotropic agent and a stabilizer which comprises at least one polycarboxylic acid or metal or ammonium salt thereof.

   2. A composition as claimed in claim 1 comprising an organic detergent, a pH modifying agent, bleach, an enzyme, a detergent builder, a sequestering agent and/or a foam inhibitor.

   3. A composition as claimed in Claim 1 or 2, wherein the polycarboxylic acid is a diner or trimer of a C8 to C22 unsaturated fatty acid.

   4. A composition as claimed in claim 1 or 2, wherein the stabilizer comprises a monovalent metal or ammonium salt of a diner or trimer of a C. to C22 unsaturated fatty acid.

   5. A composition as claimed in Claim 1 or 2, wherein the stabilizer comprises a polyvalent metal salt of a diner or trimer of a C8 to C22 unsaturated fatty acid.

   6. A composition as claimed in any one of Claims 1 to 5, wherein the stabilizer is present in an amount of from 0.001 to 1% by weight.

   7. A composition as claimed in any one of Claims 1 to 5, wherein the stabilizer is present in an amount I of from 0.01 to 0.5% by weight.

   A composition as claimed in any one of Claims 1 to 7, comprising any or any combination of i-ngredients (a) to (h), optionally at the weight percentages shown in brackets:

   (a) (5 to 35%) alkali metal tripolyphosphate.

   (b) (2.5 to 20%) sodium silicate; (c) (0 to 9%) alkali metal carbonate; (d) (0.1 to 5%) chlorine bleach stable, water- dispersible organic detergent active material; (e) (0 to 5%) chlorine bleach stable foam depressant; - (f) chlorine bleach compound (optionally in an amount to provide 0.2 to 4% of available chlorine); (g) thixotropic agent (optionally in an amount sufficient to provide the composition with a thixotropy index of about 2 to 10); (h) 0 to 8% of sodium hydroxide.

   9. A composition as claimed in any one of Claims 1 to 8, wherein the stabilizer comprises a dimer or trimer of a C8 to C22 unsaturated fatty acid.

   10. A composition as claimed in claim 9 wherein the stabilizer is present in an amount of from 0.05 to 0.2% by weight.

   11. A composition as claimed in Claim 9 or 10, 1 wherein the polycarboxylic acid comprises a diner or trimer of a C16 to C20 unsaturated fatty acid.

   12. A composition as claimed in any one of Claims 36 -1 1 to 11, wherein the stabilizer comprises adipic acid.

   13. A composition as claimed in any one of Claims 1 to 11, wherein the stabilizer comprises azelaic acid.

   14. A co-1position as claimed in any one of Claims 1 to 15, comprising wherein the thixotropic agent comprises a clay thickener.

   15. A composition as claimed in any one of Claims 1 to 14, wherein the thixotropic agent is present in an amount of from 0. 1 to 2.5% by weight.

   16. A composition as claimed in any one of Claims 1 to 15, wherein the stabilizer comprises a monovalent metal salt of a dimer or trimer of a C16 to C20 unsaturated fatty acid.

   17. A composition as claimed in any one of Claims 1 to 16, wherein the stabilizer comprises an alkali metal or ammonium salt of a dimer or trimer of a C16 to C20 unsaturated fatty acid.

   18. A composition as claimed in Claim 16 wherein the monovalent metal salt comprises a metal of the Group IA of the Periodic Table of the Elements.

   19. A composition as claimed in Claim 18, wherein the monovalent metal salt is present in an amount of 30 from 0.01 to 0.5% by weight.

   20. A composition as claimed in Claim 18, wherein the metal salt comprises sodium or potassium. 1 i 37 21. A composition as claimed in claim 19 or 20, wherein the alkali metal salt is present in an amount of about 0.05 to 0.2% by weight.

   22. A composition as claimed in any one of Claims 1 to 21, wherein the stabilizer comprises a polyvalent metal salt of a dimer or trimer of a C16 to C20 unsaturated fatty acid.

   23. A composition as claimed in Claim 22 wherein the polyvalent metal salt comprises a metal Group IIA, IIIA, IVA, VA, VIA, VIIA, IB, IIB, IIIB, IVB, VB, VIB, VIIB or VIII of the Periodic Table of the Elements 24. A composition as claimed in Claim 22 or 23, wherein the polyvalent metal salt is present in an amount of from 0.01 to 0.5% by weight.

   25. A composition as claimed in Claim 23 or 24 wherein the polyvalent metal salt comprises Mg, Ca, Ti, Zr, V, Nb, Mn, Fe, Co, Ni, Cd, Sn, Sb, Bi, Al or Zn.

   26. A composition as claimed in Claim 22, 23 or 24 wherein the polyvalent metal salt comprises a metal of Group II, III or IV of the Periodic Table of Elements.

   1 27. A composition as claimed in Claim 26 wherein the polyvalent metal salt comprises aluminium, zinc, calcium or magnesium.

   28. A composition as claimed in any one of Claims 1 1 11 38 -1 24 to 27 wherein the polyvalent metal salt is present in an amount of from 0.05 to 0.2% by weight.

   29. A composition substantially as herein described with reference to the any one of the Examples.

   30. A method for improving the stability of an aqueous, gel-like thixotropic composition having a small but effective amount of a claythixotropic agent which comprises including in the composition an effective stabilizing amount of a polyvalent salt of a diner or trimer of a C16 to C20 unsaturated fatty acid wherein the metal salt is selected from the group consisting of aluminium, zinc, calcium and magnesium.

   is 31. A method for cleaning soiled articles, which comprises contacting the soiled articles in an automatic dishwashing machine in an aqueous washbath having dispersed therein an effective amount of a composition as claimed in any one of Claims 1 to 29.

   32. A method for improving the stability of an aqueous, gel-like thixotropic composition having a thixotropic agent which comprises including in the composition an effective stabilizing amount of a diner or trimer of a CS to C22 unsaturated fatty acid or a metal or ammonium salt thereof.

   Published 1958 at The Patent Office, State House. 66'71 Higt Ho!born. London WCIR 4TP. Further copies may be obtained from The Patent OfficeSales Branch. St Mary Cray. Orpington. Rent BR5 3RD. Printed by Multiplex techniques ltd. St Mary Cray, Kent. Con. 1/87.