DK164746B - TIKSOTROPT LIQUID DISHWASH WITH IMPROVED PHYSICAL STABILITY FOR AUTOMATIC DISHWASHER AND PROCEDURE FOR CLEANING THE DISHWASH IN AN AUTOMATIC DISHWASHER UNDER USE HERE - Google Patents

Description

DK 164746B

in

The present invention relates to aqueous thixotropic automatic dishwashing agents comprising, by weight, approx.

(a) 5-35% alkali metal tripolyphosphate, 5 (b) 2.5-20% sodium silicate, (c) 0-9% alkali metal carbonate, 10 (d) 0.1-5% chlorine bleach stable, water dispersible, organic , purifying active material, (e) 0.1-5% to chlorine bleach stable, foam suppressant, (f) bleaching chlorine compound in an amount affording approx. 0.2 -4% available chlorine, (g) 0.1-10.0% thixotropic thickener in an amount of ten to 20 sufficient to give the agent a thixotropy index of approx.

2-10, (h) 0-3% sodium hydroxide, and 25 (i) water.

The dishwashing agents have thixotropic properties, improved chemical and physical stability, and are easily dispersible in the washing medium to provide effective cleaning of cutlery, glass, porcelain and the like.

The invention further relates to a method for cleaning dirty dishes in an automatic dishwasher.

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2 Dishwashing detergents for household appliances supplied in powder form have several disadvantages, e.g. a non-uniform composition that expensive operations are necessary for their preparation tends to bake together at high humidity storage, resulting in the formation of lumps which are difficult to disperse, dustiness which is a source of particular irritation to users suffering from allergies and tend to bake together in the dishwasher dispenser. Furthermore, liquid forms of such agents generally cannot be used in automatic dishwashers due to excessive foams, unacceptably low viscosities and excessive alkalinity.

Recent research and development activity has focused on the gel form or thixotropic form of such agents, e.g. abrasive cleansers and "automatic" dishwashing products characterized as thixotropic pastes. The dishwashing products thus obtained are first and foremost unfortunate in that they are insufficiently viscous to be anchored in the dispenser cup in the dishwasher, and furthermore they give stain residues on the washed articles, glass, porcelain and the like. Ideally, thixotropic cleansers should be very viscous in a calm state, be Bingham plastic in nature and have relatively high flow values. When subjected to shear forces, e.g. however, upon being shaken in a container or squeezed through an opening, they must quickly become fluid and upon cessation of the applied shear stress, they must quickly return to the highly viscous Bingham plastic state. Stability is also of primary importance, i.e. there should be no significant sign of phase separation or leakage after prolonged delay.

Providing automatic dishwasher detergents in gel form, 3 5

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3 having the aforementioned properties has thus proved problematic, especially as regards means for use in household dishwashers. For effective use, it is generally recommended that the automatic dishwasher, hereinafter referred to as ADD, contain (1) sodium tripolyphosphate (NaTPP) to soften or bind minerals in hard water and to emulsify and / or peptize dirt. (2) sodium silicate to provide the alkalinity needed for effective cleaning and to provide protection for fine porcelain glaze and patterns, (3) sodium carbonate commonly considered optional to enhance the alkalinity, ( 4) a chlorine releasing agent to aid in removing dirt stains leading to water stains; and (5) foam reducing / surfactant to reduce foam thereby increasing the efficiency of the machine and providing the necessary cleaning performance. See, e.g. SDA Detergents in Depth, “Formulations

Aspects of Machine Dishwashing ", Thomas Oberle (1974). Cleaners approaching the aforementioned compositions are mostly liquids or powders. Combining such ingredients in a gel form effective for domestic machine use has proved difficult. In general, such combinations omit hypochlorite bleach since it tends to react with other chemically active ingredients, especially surfactant, thereby degrading the suspending or thixotropic agent and damaging its effectiveness, U.S. Patent No. 4,115,308 25 soot-dropping pastes for automatic dishwashers containing a suspending agent, for example, CMC, synthetic clays or the like, inorganic salts containing silicates, phosphates and polyphosphates, a small amount of surfactant, and a foam suppressant. Patent No. 4,147,650 is somewhat similar and optionally includes Cl- (hypochlorite) bleach agent, but no organic surfactant or foam suppressant. The product is further described as a detergent slurry without any particular thixotropic properties.

U.S. Patent No. 3,985,668 discloses abrasive, abrasive cleansers

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4 of gel-like consistency containing (1) suspending agent, preferably smectite-type and attapulgite-type clays, (2) abrasive, e.g. quartz sand or perlite, and (3) filler comprising low density powdered polymers, expanded perlite 5 and the like, which have a buoyancy and thus stabilize the effect on the agent in addition to serving as a filler and thereby replacing water otherwise available to unwanted overlying layer formation due to leakage and phase stabilization. The foregoing are the essential constituents. Optional constituents include hypochlorite bleach, bleach stable, surfactants and buffers, e.g. silicates, carbonates and monophosphates. Builders, such as NaTPP, may be included as additional optional components to provide or supplement a builder function that the cushion does not provide, the amount of the builder not exceeding 15% of the total agent of the patent. Maintaining the desired pH level of 10 or more is available with the buffer / builder components. A high pH is said to decrease the decomposition of the chlorine bleach and the undesirable reaction between surfactant and bleach. When NaTPP is present, it is limited to 20 5%, as mentioned. Foam reducing agent is not disclosed.

British Patent Application Nos. 2,116,199A and 2,140,450A disclose liquid ADD agents having properties which desirably characterize a gel-type thixotropic structure containing each of the various constituents needed. -25 for efficient cleaning in an automatic dishwasher.

The normally gel-like aqueous dishwashing detergent with thixotropic properties includes the following components by weight: (a) 5 - 35% alkali metal tripolyphosphate, 30 (b) 2.5-20% sodium silicate, (c) 0-9% alkali metal carbonate, (d) 0.1-5% to chlorine bleach stable, water dispersible, organic, detergent active material,

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5 (e) 0-5% to chlorine bleach stable, foam suppressant; (f) chlorine bleach in an amount to provide approx. 0.2 to 4% available chlorine, and 5 (g) thixotropic thickener in an amount sufficient to give the agent a thixotropy index of about 2.5 - 10.

ADDs so formulated are low-foaming, readily soluble in the washing medium, and most effective at pH values that best lead to improved purity, namely pH 10.5 - 13.5. The mid-10 clays are usually of gel consistency, i.e. a high-viscous, opaque, jelly-like material that has a Bingham plastic character and therefore relatively high flow values. Therefore, a certain shear force is required to initiate or increase flow, as would be achieved in the stirred dispenser cup in an activated automatic dishwasher. Under these conditions, the agent is rapidly liquefied and readily dispersed. When the shear force is interrupted, the liquid agent quickly returns to a high-viscosity Bingham plastic state close to its former consistency.

These previously described liquid ADD compositions do not, or only to a lesser extent, have one or more of the deficiencies described above, but it has been found that in practice further improvements in physical stability are required to increase the shelf life of the product and thereby increase the consumer's acceptance thereof.

It is therefore an object of the invention to provide liquid ADD agents having thixotropic properties with improved physical stability and rheological properties.

It is also an object of the invention to provide thixotropic liquid ADD agents having reduced amounts of thixotropic thickener without detrimental effect on the generally high viscosities at low shear rates and lower viscosities at higher shear rates, which are characteristic.

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6 teristically for the desired thixotropic properties.

These objects of the invention, which will become apparent from the following detailed description and preferred embodiments of the invention, are achieved by a normally aqueous, aqueous cleanser. for automatically dishwasher incorporating an amount of a polyvalent metal salt of a long chain fatty acid which is effective in preventing the precipitation of the suspended particles 10 as thixotropic agent.

The invention therefore relates to a normal gel-like aqueous automatic dishwashing detergent having thixotropic properties containing on a weight basis: (a) 5-35% alkali metal tripolyphosphate, (b) 2.5-20% sodium silicate, (c) 0-9% alkali metal carbonate , (20) (a) 0.1-5% to chlorine bleach stable, water dispersible, organic, detergent, (e) 0.1-5% to chlorine bleach stable, foam suppressant, (25) chlorine bleaching agent in an amount which gives approx. 0.2-4% available chlorine, (g) 0.1-10.0% thixotropic thickener in an amount sufficient to give the agent a thixotropic i-index of about

2.0-10, (h) 0-3% sodium hydroxide, and (i) water, which is characterized in that it further comprises (j) 0.08-0.40% of a polyvalent metal salt. of a 1-chain fatty acid having 8-22 carbon atoms as a stabilizer, the remainder being water.

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7

Another aspect of the invention discloses a method for cleaning dirty dishes in an automatic dishwasher, which is characterized in that the dirty dishes are placed in the automatic dishwasher in contact with an aqueous washing bath, in which an effective amount of the agent according to the invention is dispersed by pouring this agent into the dispensing cup of the automatic dishwasher, allowing the agent to thicken in the dispensing cup, and then subjecting this agent to shear forces, such as a water jet, in the dishwasher.

In practicing the method, the LADD agent can be easily poured into the dispensing cup of the automatic dishwasher and will, in just a few seconds, thicken to its normal gel-like state and remain safely inside the dispensing cup until shear forces are again applied thereto, such as by water spraying from dishwasher.

In general, the ADD efficiency is directly related to (a) available chlorine levels, (b) alkalinity, (c) solubility 20 in the washing medium, and (d) foam inhibition. It is preferred according to the invention that the pH of the ADD be at least about 9.5, more preferably from ca. 10.5 to 13.5 and most preferably at least approx. 11.5. At relatively lower pHs, the ADD product is for viscous, i.e. as a solid and is therefore not readily liquefied under the shear forces created in the dispensing cup under normal operating conditions of the machine. The result is that the agent loses much, if not all, of its thixotropic character. Thus, addition of NaOH is often necessary to increase the pH to the above ranges and to increase the flow properties. Presence of carbonate is also often necessary as it acts as a buffer to help maintain the desired pH level. Too much carbonate must be avoided as it can cause the formation of needle-like crystals of carbonate, thereby damaging the stability, thixotropy and / or purity of the ADD-35 product. Sodium hydroxide (NaOH) further serves to neutralize the foam-suppressing phosphoric acid or phosphoric acid.

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8 acid residues when present. The agent contains 0.5-3 wt% NaOH and 2-9 wt% sodium carbonate. 0.5-3 wt% NaOH and 2-9 wt% sodium carbonate in the agent are typical, although it should be noted that ten liters of stretch in the g alkaline can be provided with 5

NaTPP and sodium silicate.

The NaTPP used in the agent in an amount of 5-35% by weight, preferably approx. 20-30% by weight should preferably be free of heavy metal which tends to decompose or inactivate the preferred sodium hypochlorite or other chlorine bleaching compounds. The NaTPP may have an average degree of hydration less than about. 1 or more than approx. 5, e.g. from 0 to 2.7% by weight or at least 16.5% water, including the stable hexahydrate having a hydration degree of 6, corresponding to approx. 18% by weight water or more.

Moisture to an average of approx. Indeed, 0.3-1% water is very effective in that it is thought to serve to form seed crystals of the stable hexahydrate which promote hydration and solubilization of the other NaTPP particles. On average, 20 NaTPP contains approx. 5-15% by weight of water, corresponding to an average degree of hydration of approx. 1-5. If only the hexahydrate is used, the cleaning product is liquid and has no or little thixotropic character. If only the anhydrous NaTPP is used, the product is too thick and therefore unsuitable. Effective agents are obtained, for example, when using a weight ratio of 0.5: 1 - 2: 1 between anhydrous and hexahydrated NaTPP, and values of approx. 1: 1 is particularly preferred.

Foam inhibition is important to increase the efficiency of the dishwasher and reduce destabilizing effects that could occur as a result of the presence of excess foam in the washing machine during use. Foam can be sufficiently reduced by appropriate choice of the type and / or amount of detergent which is the most important foam producing component. The degree of foam also depends on the hardness of the wash water in the machine, whereby adjusting the amounts of NaTPP having a water softening effect can help to provide the desired degree of foam inhibition.

However, it is generally preferred to include a chloro-

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9 bleach stable, foam suppressant or inhibitor. Particularly effective are the alkyl phosphonic acid esters of formula 50

HO - P - R OR

which can be obtained e.g. from BASF-Wyandotte (PCUK-PAE), and especially the acidic alkyl phosphate esters of formula 0

HO - P - OR

OR

15 which can be obtained e.g. from Hooker (SAP) and Knapsack (LPKn-158), wherein one or both R groups in each type of ester may independently represent a Mixture of the two types or other types which are stable to chlorine bleach, or mixtures of mono- and di-esters of the same type may be used. Particularly preferred is a mixture of mono- and di-C ^ g_ g-acidic alkyl phosphate esters such as monostearyl / distearyl-acid phosphates 1.2 / 1 (Knapsack). When used, amounts of 0.1 to 5% by weight, preferably approx. Typically, from about 0.1 to about 0.5% by weight, foam suppressant in the agent, with the weight ratio of active cleansing compound (d) to foam suppressant (e) generally being from about 10: 1 to 1: 1 and preferably from ca. 4: 1 to 1: 1. Other foam suppressants which may be used include, e.g. the known silicones.

30

Although any bleaching chlorine compound can be used in the agents of the invention such as dichloroisocyanurate, dichlorodimethylhydantoin or chlorinated TSP, alkali metal hypochlorite is preferred, e.g. potassium, lithium, magnesium and especially sodium hypochlorite. The agent must contain sufficient very bleaching chlorine compound

V D

to give approx. 0.2 - 4.0% by weight of available chlorine, determined e.g. by acidifying 100 parts of the agent with excess hydrochloric acid. A solution containing approx. 0.2 - 4.0 wt% sodium hypochlorite in- 10

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they contain or give essentially the same percentage of chlorine available. From approx. 0.8 to 1.6% by weight of available chlorine are particularly preferred. For example, sodium hypochlorite (NaOCl) solution with 11 or 13% available chlorine can be advantageously used in amounts of about 3-20%, preferably approx. 7 - 12%.

The sodium silicate, which provides alkalinity and protection of hard surfaces, such as fine porcelain glaze and porcelain pattern, is used in an amount ranging from 2.5 to 20 wt. 5-15 wt., In the agent. The sodium silicate is generally added in the form of an aqueous solution which preferably has a Na 2 O: SiO 2 ratio of approx. 1: 2.2 - 1: 2.8. At this point it should be mentioned that most of the other components of the present agent, especially NaOH, sodium hypochlorite, foam suppressant and thixotropic thickening agent are also often added in the form of a pre-made aqueous dispersion or solution.

Purifying active material useful in the invention should be stable in the presence of chlorine bleach, especially hypochlorite bleach, and preferably include those of the organic, anionic, water dispersible, surfactant type, amine oxide type, phosphine oxide type, sulfoxide type, or betaine type. the former being the most preferred anionic substances. They are used in amounts ranging from 0.1 to 5%, preferably 0.5 to 2.0% and more preferably about 0.3 - 0.8%. Particularly preferred surfactants for the invention are the linear or branched alkali metal mono- and / or -di- (Cg-14) alkyl diphenyloxide mono- and / or disulfates commercially available e.g. such as DOWFAX (registered product-30 mark) * 3B-2 and DOWFAX 2A-1. In general, the paraffin sulfates tend to damage, albeit not destroy the thixotropy, as they have been shown to increase viscosity too much and cause

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severe shear force problems. In addition, the surfactant must be compatible with the other constituents of the agent. Other suitable surfactants include the primary alkyl sulfonates, alkyl sulfonates, alkylarylsulfonates and secondary δ alkyl sulfates. Examples are sodium C ^ Q g alkyl sulfates such as sodium dodecyl sulfate and sodium tallow alcohol sulfate, sodium C ^ Q_ alkanesulfonates such as sodium hexadecyl-1-sulfonate and sodium Cisisisalkylbenzenesulfonates such as sodium dodecylbenzene sulfate. The corresponding potassium salts may also be used.

10

Like other suitable surfactants or detergents, the surfactant amine oxide agents typically have the structure I R 2 NO where each R represents a lower alkyl group, e.g. methyl and R represents a long chain alkyl group having from 8 to 22 carbon atoms, e.g. a lauryl, myristyl, palmityl or cetyl group. Instead of an amine oxide, a corresponding surfactant phosphine oxide R, R 2 PO or sulfoxide RR 2 SO may be used. Typically, surface-active betaines have the structure R2R N-R "COO, wherein each R represents a lower alkylene group having from 1 to 5 carbon atoms. Specific examples of these surfactants are lauryl dimethyl amine oxide, myristyldimethyl amine oxide, the corresponding phosphine oxides and sulfoxides and the corresponding betaines, including dodecyldimethylammonium acetate, tetradecyldiethylammonium pentanoate, hexadecyldimethylammonium hexanoate, etc. To be biodegradable, the alkyl groups in these surfactants must be linear and these compounds preferred.

Surfactants of the foregoing type, all of which are well known, are disclosed in U.S. Patents Nos. 3,985,668 and 4,261,030.

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Thixotropic thickeners, i.e. Thickeners or suspending agents which give an aqueous medium thixotropic properties are well known and can be organic or inorganic, water soluble, water dispersible or colloid forming and monomeric or polymeric and must of course be stable in these agents, e.g. stable to high alkalinity and bleaching chlorine compounds such as sodium hypochlorite. Particularly preferred are generally the inorganic, colloid-forming clays of the smectite and / or attapulgite type. These materials were generally used in amounts of approx. 1.5 - 10, preferably 2-5% by weight, to impart the desired thixotropic properties and the Bingham plastic nature of the previously described ADD compositions of GB 2.116.199A and GB 2.140.450A. It is one of the advantages of the ADD agents of the invention that the desired ticotropic properties and the Bingham plastic nature can be obtained in the presence of the stabilizing agents of polyvalent metal salt of fatty acid with smaller amounts of the thixotropic thickeners. Amounts of the inorganic colloid-forming clays of the smectite and / or attapulgite type in the range of 0.1 to 3%, preferably 0.2 to 2.5%, especially 0.5 to 2.2%, are e.g. generally sufficient to achieve the desired thixotropic properties and the Bingham plastic character when used in combination with the physical stabilizer.

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Smectite clays include montmorillonite (bentonite), hectorite, saponite and the like. Materials of this type are commercially available as "Thixogel" (registered trademark) No. 1 and "Gel White" (registered trademark) GP, H etc. from Georgia Kaolin Company (both are 30 35

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13 montmorillonites). Attapulgite clays include materials commercially available under the trade name "Attagel" (registered trademark), ie "Attagel" 40, "Attagel" 50, and "Attagel" 150 from Engelhard Minerals and Chemicals Corporation. Mixtures of smectit-5 and attapulgate types in 4: 1 - 1: 5 weight ratios are also useful.

Thickeners or suspending agents of the foregoing types are well known and are described e.g. in the aforementioned U.S. Patent No. 3,985,668. Abrasives or polishes should be avoided.

The amount of water contained in these agents must, of course, not be so high as to give too low viscosity and flow unit, nor so low as to give too high viscosity and poor flowability, in both cases reducing or destroying thixotropic properties. The amount is easily determined by routine experimentation in a given case and usually ranges from approx. 45 to 75% by weight, preferably approx. 55 - 65% by weight. The water should also preferably be deionized or softened.

20

Unless otherwise stated, the description of the ADD product above corresponds to the agents described in the aforementioned British Patent Application Nos. 2,116,199A and Nos. 2,140,450A.

The ADD products of these descriptions exhibit improved rheological properties judged by testing the viscosity of the product as a function of shear rate. The agents showed higher viscosity at a low shear rate and lower viscosity at a high shear rate, which data shows effective 30 3 5

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14 flow cleaning and gelation within the shear rates that occur in dishwashers. In practice, this meant improved slope and improved processing properties as well as less leakage in the dispenser cup of the machine compared to previously known 5 liquid or gel ADD products. For applied shear rates corresponding to 3-30 rpm. The viscosities (Brookfield) were correspondingly from about 1 minute. 15,000 to 30,000 centi-poise to approx. 3,000 - 5,000 centipoise, measured at room temperature using a LVT Brookfield viscometer after 3 minutes using a spindle # 4. A shear rate of 7.4 sec. ^ corresponds to one spindle speed per minute of approx. 3. An approx. a twofold increase in the shear rate produced a 6-7 fold reduction in viscosity. With prior art ADD gels, the corresponding reduction in viscosity was only approx. 2 times.

With these agents, the initial viscosity measured at ca. 3 rpm minute, and only approx. 2,500 - 2,700 centipoise. Thus, the agents of the aforementioned inventions exhibit threshold values of the liquefaction at low shear rates and of a significantly greater extent, expressed by increases in shear rate as a function of decrease in viscosity. This property of the prior art ADD products is summarized as a thixotropic index (TI), which is the ratio of apparent viscosity at 3 rpm. per minute and at 30 rpm. minute. The prior art agents have a TI 25 from 2.5 to 10. The tested ADD agents showed substantial and rapid return to the former consistency in a calm state when the shear force was interrupted.

The present invention is based on the discovery that the physical stability, i.e. the resistance to phase separation, precipitation, etc., of these previously known liquid aqueous ADDs can be greatly enhanced without adversely affecting, and in some cases favorably affecting their rheological properties, by adding a small but effective amount of polyvalent metal salt of a long chain fatty acid.

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15

As an example of the improvement of the rheological properties, it has been found that at low shear rates, e.g. at a spindle rotation of approx. 3 pr. The apparent viscosities can often be increased from two to three times with the incorporation of as little as 0.2% or less of the fatty acid metal salt as a stabilizing agent. At the same time, physical stability can be improved to such an extent that even after 6 weeks or longer, within temperature ranges ranging from near the freezing point to 40 ° C and above, the agents containing the metal salt as stabilizing agent do not undergo any visible phase separation.

The preferred long chain fatty acids are higher aliphatic fatty acids having from about 8 to approx. 22 carbon atoms, more preferably from about

10 to 20 carbon atoms and especially preferably from about 12 to 18 carbon atoms, including the carbon atom of the fatty acid carboxyl group.

The aliphatic radical may be saturated or unsaturated and may be straight or branched. Mixtures of fatty acids can be used, such as those derived from natural sources, such as tallow fatty acid, coconut fatty acid, soy fatty acid, etc.

Examples of the fatty acids from which the polyhydric metal salt can be formed include, e.g. decanoic acid, dodecanoic acid, palmitic acid, myristic acid, stearic acid, oleic acid, eicosanoic acid, tallow fatty acid, coconut fatty acid, soy fatty acid, mixtures of these acids etc. Stearic acid is preferred, both because of industrial availability and because of the results.

The preferred polyvalent metals are aluminum and zinc, but other polyvalent metals, especially those of Group IIA, IIIA, IVA, VA, VIA, VIIA, IIB, HIB, IVB, VB and VIII of the Periodic Table, may also be used. Concrete examples of these other polyhydric metals include Mg, Ca, Ti, Zr, V, Nb, Mn, Fe, Co, Ni, Cd, Sn, Sb, Bi 30, etc. Preferably, the metal salts are used in their higher oxidation states.

Many of these metal salts are industrially available. E.g

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16, the aluminum salts are obtained in the triacid form, e.g. aluminum stearate as aluminum tristearate, Al (C17H35COO) 3. Monoacid salts, for example. aluminum monostearate, Al (OH) 2 (C ^H ^COO), and diacid salts, e.g. aluminum distearate, Al (OH) (C17H35COO) 2 and mixtures of two or three of these mono-, di- and tri-acid salts can be used for these metals, e.g. Al with valence +3, and mixtures of mono- and diacid salts can be used for these metals, e.g. Zn with valences of +2. It is most preferred that the diacids of + 2-valent metals and the trisacids of + 3-valent metals and the tetra acids of 10 + 4-valent metals are used in predominant amounts. For example, at least 30%, preferably at least 50%, and most preferably from 80 to 100%, of the total metal salt is in the highest possible oxidation state, i.e. that each of the possible valence sites is occupied by a fatty acid residue.

The metal salts, as mentioned above, are generally industrially available but can be readily prepared, e.g. by saponifying a fatty acid, e.g., animal fat, stearic acid, etc., or the corresponding fatty acid ester, followed by treatment of a hydroxide or oxide of the polyhydric metal, e.g. in the case of the aluminum salt, with alum, alumina etc.

Aluminum stearate, i.e. aluminum tristearate, and zinc stearate, i.e. zinc distearate, are the preferred polyhydric fatty acid salts as stabilizers.

The amount of stabilizing fatty acid salt, in order to achieve the desired increase in physical stability, will depend on such factors as the nature of the fatty acid salt, the nature and amount of the thixotropic agent, the purifying active compound, inorganic salts, especially TPP, other ADD constituents, and the expected storage conditions and shipping conditions.

However, in general, amounts of the polyhydric metal fatty acid salt as stabilizing agent in the range of about 0.02 to 1%, preferably from ca. 0.06 to 0.8%, especially preferably from about 0.08

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17 to 0.4%, the long-term stability and absence of phase separation at standstill or during transport at both low and high temperature necessary for a commercially acceptable product.

According to a preferred process for preparing these agents, all the inorganic salts must be dissolved or dispersed first. te, i.e. carbonate (when used), silicate and tripolyphosphate, in the aqueous medium. Thickener is added last. The foam suppressant (when used) is initially provided as an aqueous dispersion, and the same applies to the thickening agent. The dispersion of foam suppressant, sodium hydroxide (when used) and inorganic salts are first mixed at elevated temperature in aqueous solution (deionized water) and then cooled using stirring constantly. Bleach, surfactant, fatty acid salt, stabilizer and thickener dispersion at room temperature are then added to the cooled (25 - 35 ° C) solution. When the bleaching chlorine compound is not taken into account, the total salt concentration (NaTPP, sodium silicate and carbonate) is generally from ca. 20 to 50% by weight, preferably approx. 30-40% by weight, of the 20 agent.

Other usual constituents may be included in these agents in small amounts, which are generally less than about 10%. 3% by weight such as perfume, hydrotropic agents such as sodium benzenesulfonate, toluene sulfonate, xylene sulfonate and cumene sulfonate, preservatives, dyes and pigments and the like, all of which are stable to bleaching chlorine compounds and high alkalinity (properties of all components) ). Particularly preferred for staining are the chlorinated phthalocyanines and aluminum silicate polysulfides which give a pleasant green and blue color respectively. TiO 2 can be used to whiten or neutralize impure color shades.

The liquid ADDs of the invention are readily used in known manner for washing in an automatic dishwasher equipped with a suitable detergent dispenser in an aqueous bath containing

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18 an effective amount of the agent.

The invention can be practiced in various ways, and some specific embodiments are described to illustrate the invention with reference to the Examples.

5 Unless otherwise stated, all quantities and proportions are by weight of the agent.

EXAMPLE 1.

To demonstrate the effect of the metal salt stabilizer, liquid ADD compositions with varying amounts of stabilizer and thixotropic thickener are prepared. First, the following ingredients are mixed in a Guisti mixer at 50 - 60 ° C:

Ingredients%

Deionized water 41.10 + y-x

Sodium hydroxide solution (50% NaOH) 1.00 Sodium carbonate, anhydrous 5.00

Sodium silicate, 47.5% solution of Na 2 O: SiC> 2 in a ratio of 1: 2.4 15.74

Sodium TPP (essentially anhydrous, i.e. 0 - 5%, especially 3% humidity) 20 ("Thermphos" NW) 12.00

Sodium TPP (hexahydrate) CThennphosnN hexa) 12.00

The mixture is cooled to 25-30 ° C and stirring is maintained all the time, and the following ingredients are added at room temperature:

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19

Ingredient% 5 Sodium hypochlorite solution (11% available chlorine) 9.00

Monostearyl phosphate 0.16 DOWFAX® 3B-2 (45% Sodium monodecyl / didecyl diphenyloxide disulfonate, 10 aqueous solution) 0.80

Al-tristearate or Zn-distearate x "Gel White H" montmorillonite 2.00-y

The foam-suppressing monostearyl phosphate and the purifying active compound, D0WFAX® 3B-2, are added to the mixture just before the aluminum tristearate or zinc distearate or just before the thickener, "Gel White H".

Each of the resulting liquid ADD compositions shown in Table I 20 is measured for density, CDR (capillary drainage rate), apparent viscosity at 3 and 30 rpm. per minute and physical stability (phase separation) after standing and during a shipment test. The results are also shown in Table I.

25

The following conclusions can be drawn from the data in Table I:

Incorporation of 0.2% Al stearate in a 1.5% or in a 1% Gel White H-containing composition and incorporation of 0.1% Al stearate or 0.1% zinc stearate in a 2% The% "Gel White H" -containing composition leads to a simultaneous increase in physical stability and apparent viscosity (Table I, Experiment 1 (Control), 2, 3, 6 and 9).

Incorporation of 0.1% Al stearate into a 1% Gel White H-containing composition, 0.2% Al stearate into a 0.5% Gel White H-containing composition and 0 , 3 or 0.4% Al stearate in a 20

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0.25% "Gel White H" -containing composition leads to an increase in physical stability without any drastic viscosity increase (Table II, Experiment 1 (control), 4, 7, 10 and 11).

5

For the combination of 0.1% Al stearate and 0.5% Gel White H (Experiment 8), the apparent viscosity values in remain acceptable but no significant improvement in physical stability is obtained.

10 15 20 25 30 35

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Notes to Table I: (1) 1 filter paper (Whatman) with a 6.4 cm circle drawn thereon is laid on a flat glass sheet, 10 x 10 cm. A plastic tube, 6.4 cm long, 3.4 cm in diameter, is placed in a standing position centered on the circle. The tube is filled with a sample of the liquid ADD (after one day). The time required for the solvent to leak out of the tube and reach the drawn circle is measured. Time is measured on three sides of the circle and an average is taken. Faster times mean that the gel does not hold the solvent (water) well, and that this can leak into the filter paper. Times greater than 5 minutes are considered good. Times between 4 and 5 minutes are considered unstable but acceptable.

(2) Measured with spindle # 4 after 3 minutes on a 24 hour sample.

15 (3) In height.

(4) By weight.

(5) At 4 ° C, room temperature (= 20-2 ° C), 35 ° C and 43 ° C in glass bottle (6) Liquid separation measured after 6 weeks and 3,000 km in a private car (weight in a plastic bottle).

EXAMPLE 2.

Using the same composition and preparation method as in Example 1, except that 2% "Attagel" 50 (an attapulgitre) or 0.4% "Bentone" EW (instead of Gel White H as thixotropic thickener) was used. a specially processed 25 hectorite clays together with (experiments 2 and 4) or without (control experiments 1 and 3) aluminum tristearate. Apparent viscosity and physical stability were measured in the same manner as described in Example 1. The results are shown in Table II.

DK 164746 B

25

From the results in Table II, it can be seen that small amounts of aluminum stearate are equally effective in increasing the physical stability of liquid, thixotropic automatic dishwashing agents based on attapulgit clay and hectorite clay.

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EXAMPLE 3.

This example shows that inorganic aluminum and zinc salts, including A ^ O ^, ZnSO ^ and A12 (SC> 4) 3, and the monovalent metal fatty acid salts do not provide improved physical stability of the liquid thixotropic ADD agents. Using the same composition 5 as in Experiment 6 of Example 1, 0.1% of each of Al2 O3, ZnSO4, A12 (SO4) 3 and sodium stearate was used instead of 0.1% aluminum stearate. The results of the measurements of apparent viscosity and physical stability are shown in Table III.

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Claims (15)

1. Aqueous, thixotropic automatic dishwasher detergent by weight approx. (a) 5 - 35% alkali metal tripolyphosphate, (c) 0 - 9% alkali metal carbonate, (d) 0.1 - 5% against chlorine bleach stable, water dispersible, organic, detergent, 5 (e) 0.1 - 5% to chlorine bleach stable, foam suppressant, (f) bleaching chlorine compound in an amount affording approx. 0.2 - 4% available chlorine, (g) 0.1 - 10.0% thixotropic thickener in an amount 10 sufficient to give the agent a thixotropy index of approx. 2 - 10, (h) 0 - 3% sodium hydroxide, and (i) water, characterized in that it further comprises 15 (j) 0.08 - 0.40% of a polyvalent metal salt of a long chain 8-22 fatty acid. carbon atoms as physical stabilizers, the remainder being water. An agent according to claim 1, characterized in that the physical stabilizer (j) is constituted by the Mg, Ca, Al or Zn salt of an aliphatic fatty acid having 10-20 carbon atoms. An agent according to claim 1 or 2, characterized in that the physical stabilizer (j) is a polyvalent metal salt of an aliphatic fatty acid having 12 to 18 carbon atoms. Agent according to any one of the preceding claims, characterized in that the physical stabilizer (j) is constituted by a polyvalent metal salt of stearic acid, formic acid, palmitic acid, oleic acid, tallow fatty acid or soy fatty acid or a mixture thereof. Agent according to any one of the preceding claims, characterized in that the physical stabilizer (j) is made up of 35 alum in nine umtristearate or zinc distearate. DK 164746 B Na2 = S102 = 2.4) 7.48 Monostearyl phosphate 0.16 DOWFAX®3B-2 0.37 "Thermphos" NW 12.0 "Thermphos" N hexa 12.0 An agent according to claim 1 / characterized in that the thixotropic thickener (g) is constituted by an inorganic cow 11 o-forming clay. 5 A composition according to claim 6, characterized in that the clay is an attapulgite clay or a smectite clay. A composition according to claim 6, characterized in that the amount of the clay thickener is approx. 0.1 - 3%. 10 A composition according to claim 1, characterized in that it contains approx. 0.5 - 2% inorganic carbon-forming clay as thixotropic thickener (g). 15 Agent according to claim 1, characterized in that it has a pH value of from 10.5 to approx. 13.5. Aluminum tristearate 0.1 Sodium carbonate, anhydrous 4.9 Sodium hydroxide solution (38% NaOH) 3.0 "Pharmagel Ex Uroclay" 15 (Mg / Al silicate clay) 1.25 Sodium hypochlorite solution (11%) 1/0 Water balance pH = 12.5 to 12.9 20 Smaller amounts of perfume, color, etc. can also be added to the composition. Claims. Agent according to claim 1, characterized in that the foam suppressant (s) is an acidic all the cooling phosphate. An agent according to claim 1, characterized in that the amount of alkali metal carbonate (c) is approx. 2 - 9%. Agent according to claim 1, characterized in that the amount of sodium hydroxide (h) is approx. 0.5 - 3%. An agent according to claim 1, characterized in that it has a density of approx. 1.29 g / cm 3. Method for cleaning dirty dishes in an automatic dishwasher, characterized in that the dirty dishes are placed in the automatic dishwasher in contact with an aqueous washing bath, wherein an effective amount of the agent according to any of the preceding requirements are dispersed by pouring the agent into the dispensing cup of the automatic dishwasher, letting the agent thicken in the dispensing cup, and then subjecting the agent to shear forces, such as a water jet, in the dishwasher. 10 15 20 25 30 35