AU662904B2 - Linear viscoelastic aqueous liquid automatic dishwasher detergent composition - Google Patents

Description

6 2 9 04

AUSTRALIA

Patents Act 1990 COLGATE-PALMOLIVE COMPANY

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: LINEAR VISCOELASTIC AQUEOUS LIQUID AUTOMATIC DISHWASHER DETERGENT COMPOSITION C, i

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If I tf t i 4 i <f a(1 The following statement is a full description of this invention including the best method of performing it known to us:i' i r?-~-iEYL_ Background of the Invention Liquid automatic dishwasher detergent compositions, both aqueous and nonaqueous, have recently received much attention, and the aqueous products have achieved commercial popularity.

The acceptance and popularity of the liquid formulations as compared to the more conventional powder products stems from the convenience and performance of the liquid products.

,16 However, even the best of the currently available liquid formulations still suffer from two major problems, product phase instability and bottle residue, and to some extent cup leakage from the dispenser cup of the automatic dishwashing S machine.

a o Representative of the relevant patent art in this area, mention is made of Rek, U.S. Patent 4,556,504; Bush, et al., U.S. Patent 4,226,736; Ulrich, U.S. Patent 4,431,559; Sabatelli, U.S. Patent 4,147,650; Paucot, U.S. Patent 4,079,015; Leikhem, U.S. Patent 4,116,849; Milora, U.S. Patent 4,521,332; Jones, U.S. Patent 4,597,889; Heile, U.S. Patent 4,512,'908; Laitem, U.S. Patent 4,753,748; Sabatelli, U.S.

Patent 3,579,455; Hynam, U.S. Patent 3,684,722: other patents relating to thickened detergent compositions include U.S.

Patent 3,985,668; U.K. Patent Applications GB 2,116,199A and GB 240,450A; U.S. Patent 4,511,487; U.S. Patent 4,752,409 (Drapier, et U.S. Patent 4,801,395 (Drapier, et al.); U.S. Patent 4,801,395 (Drapier, et al.).

a' Brief Description of the Drawings Figures 1-13 are rheograms, plotting elastic modules G' and viscous modulus G" as a function of applied strain, for the compositions of Example 1, Formulations A, C, D, G, J, H, I and K, Example 2, A and B, Example 3, L and M and Comparative Example 1, respectively and Figures 14-30 are rheograms as functions of frequency and applied strain for the compositions of Example V.

Summary of the Invention :0 According to the present invention there is provided o° novel aqueous liquid automatic dishwasher detergent o composition. The composition is characterized -by it linear viscoelastic behavior, substantially indefinite ability against phase separation or settling of disso ved or suspended 0,1-o particles, low levels of bottle residue, latively high bulk density, and substantial absence of u ound or free water.

This unique combination of propert's is achieved by virtue of the incorporation into the aque s mixture of dishwashing detergent surfactant, alkali metal detergent builder salt(s) and chlorine bleach comp nd, a small but effective amount of high molecular weigh cross-linked polyacrylic acid type thickening agent, physical stabilizing amount of a long chain fatty a d or salt thereof, and a source of potassium ions to pr ide a potassium/sodium weight ratio in the range of fro 1:1 to 45:1, such that substantially all of the det gent builder salts and other normally solid detergent dditives present in the composition are present dissolved in the aqueous phase. The compositions are further characterized ir

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-2/1- According to the present invention there is provided a polymeric composition which comprises: 0.5 to 14 weight percent of a polymeric complex which comprises an alkali metal neutralized anionic polymer having a molecular weight of 100,000 to 10,000,000 wherein said anionic polymer is complexed with a metal oxide structuring agent, a weight ratio of said alkali metal neutralized anionic polymer to said structuring agent being 1:10 to 10:1; and water, wherein the polymeric composition has a Brookfield viscosity measured with a #6 spindle at room temperature and rmps of 700 cps to 27,000 cps.

A novel aqueous liquid automatic dishwasher detergent composition may be produced from the polymeric compositions according to the invention. This composition is characterized by SQo its linear viscoelastic behaviour, substantially indefinite o0 stability against phase separation or settling of dissolved or 0 suspended particles, low levels of bottle residue, relatively high -bulk density, and substantial absence of unbound or free water.

-This unique combination of properties is achieved by virtue of the incorporation into the aqueous mixture of dishwashing detergent surfactant, alkali metal detergent builder salt(s) and chlorine S bleach compound, a small but effective amount of high molecular weight cross-linked polyacrylic acid type thickening agent, a 4404 o physical stabilizing amount of a long chain fatty acid or salt thereof, and a source of potassium ions to provide a potassium/sodium weight ratio in the range of from 1:1 to 45:1, such that substantially all of the detergent builder salts and other normally solid detergent additives present in the Scomposition aware present dissolved in the aqueous phase. The composition are further characterized

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by a bulk density of at least 1.32 g/cc, such that the density of the polymeric phase and the density of the aqueous (continuous) phase are approximately the same.

Dletailed Description of the Preferred Embodiments F The compositions of this invention are aqueous liquids

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containing various cleanising active ingredients, detergent 4 adjuvants, structuring and thickening agents and stabilizing components, although some ingredients may serve more than one of these functions.

4 :H The advantageous characteristics of the compositions of thsinvention, including physical stability, low bottle I 0 0 residue, high cleaning performance, e.g. low spocting and filming, dirt residue removal, and so on, and superior aesthetics, are believed to be attributed to several interrelated factors such as low solids, i.e. undissolved particulate content, product density and linear viscoelastic rheology. These factors are, in turn, dependent on several critical compositional components of the formulations, namely, the inclusion of a thickening effective amount of polymeric thickening agent having high water absorption capacifty, exemplified by high molecular weight cross-linked polyacrylic acid, inclusion of a physical stabilizing amount of a long chain fatty acid or salt thereof, (3) potassium ion to sodium ion weight ratio K/Na in the range of from 1:1 to 45:1, especially from 1:1 to 3:1, and a product bulk density of at least 1.32 g/cc, such that the bulk density and liquid phase density are the same.

3 AliI) lil The polymeric thickening agents contribute to the linear viscoelastic rheology of the invention compositions. As used herein, "linear viscoelastic "or" linear viscoelasticity" means that the elastic (storage) moduli and the viscous '(loss) moduli are both substantially independent of strain, at least in an applied strain range of from 0-50%, and preferably over an applied strain range of from 0-80%. More specifically, a composition is considered to be linear viscoelastic for purposes of this invention, if over the strain range of 0-50% the elastic moduli G' has a minimum value of 100 dynes/sq.cm., preferably at least 250 dynes/sq.cm., and varies less than 500 dynes/sq.cm, preferably less than 300 dynes/sq.cm., especially preferably less than 100 dynes/sq.cm. Preferably, the minimum value of G' and maximum variation of G' applies over the strain range of 0 to 80%. Typically, the variation in loss moduli G" will Sbe less than that of As a further characteristic of the preferred linear viscoelastic compositions the ratio of G"/G (tan& is less than 1, preferably less than 0.8, but more than 0.05, preferably more than 0.2, at least over the strain range of 0 to 50%, and preferably over the strain range of 0 to It should be noted in this regard that strain is shear E strain x100.

By way of further explanation, the elastic (storage) modulus G' is a measure of the energy stored and retrieved when a strain is applied to the composition while viscous (loss) modulus G" is a measure to the amount of energy 4 dissipated as heat when strain is applied. Therefore, a value of tand, 0.05< tan S <1, preferably 0.2 tanJY< 0.8 means that the compositions will retain sufficient energy when a stress or strain is applied, at least over the extent expected to be encountered for products of this type, for example, when poured from or shaken in the bottle, or stored in the dishwasher detergent dispenser cup of an automatic 0 dishwashing machine, to return to its previous condition when the stress or strain is removed. The compositions with tan values in these ranges, therefore, will also have a high cohesive property, namely, when a shear or strain is applied I.1o to a portion of the composition to cause it to flow, the surrounding portions will follow. As a result of this cohesiveness of the subject linear viscoelastic compositions, S the compitin will readily flow uniformly and homogeneously S9, from a bottle when the bottle is tilted, thereby contributing 'O0 to the physical (phase) stability of the formulation and the low bottle residue (low product loss in the bottle).-whih charactcrizcc the invention mpo.iticn.- The linear viscoelastic property also contributes to improved physical stability against phase separation of any undissolved suspended particles by providing a resistance to movement of the particles due to the strain exerted by a particle on the surrounding fluid medium.

i 3 i1 dB 3 I -1 r tj S/-ke cPMor opoci-boA efreenr- i rr i prcsnt invention also relates to polymeric eempeoitions which are thickened aqueous polymeric solutions formed from water and 0.1 to 20 weight more preferably to 14 weight percent of a polymeric complex which tomprises an alkali metal neutralized anionic polymer having a molecular weight of 60,000 to 10,000,000 complexed at a pH of 7-10 with a structuring agent such as an amphoteric metal oxide compound having a particle size of 0.5 to 40 microns, which improves the formation of the polymeic matrix of the ID" anionic polymer, wherein a weight ratio of the alkali metal wo g S neutralized anionic polymer to the amphoteric metal oxide Q o o compound is 10:1 to 1:10 and the aqueous thickened polymeric solution has a pH of 7 to 10 and a complex viscosity at radians/seconds at room temperature as applied for 30 seconds of 2 to 800 dynes seconds/sq.cm..

The aqueous thickened polymeric solution has a G' of at least 80 dynes/sq.cm. at 10 radians/second, a G" of at least 10 dynes/sq.cm., a ratio of of less than 1 and G' is substantially linear over a range of frequency of 0.1 to '2j iradians/second and a Brookfield viscosity at RT at 20 rpms with a #6 spindle of 700 to aoubt 27,000 cps. When the aqueous thickened polymeric solution has a minimum yield stress at least 2, dynes/sq.cm., more preferably 2 to 1200 dynes/sq.cm., it is capable of suspending solid particles such as alkali metal silicates and alkali metal detergent builder salts such that they will not settle out of solution.

6 -yu The solid particles to be suspended are not limited to alkali metal compounds, but can be any metal containing compound, organic compound, polymeric compound or even glass beads.

The structuring agents such as the amphoteric materials 6.f the instant invention are preferably aluminum oxides having a powdered particle size of 10-20 microns, a particle size dispersed in water of 10 to 60 nanometers, a powdered surface area of 180-250 m 2 and a crystalline size of less than 60 microns. An especially preferred aluminum oxide is ib Dispal T23 sold by Vista Chemicals. Also suitable structuring S agents are mixtures of aluminum oxides and magnesium oxides, 1 zeolites, synthetic clays such as laponite, calcium rich clays such as Promat. Natural clays such as Bentonite, Hectorite and Attapolgite and polymeric aluminum salts sold by Reheis are also useful as a structuring agent.

It is an object of the instant invention to provide S" thicken aqueous polymeric solutions which exhibit both increased viscosity and an improved degree of shear insensitivity, wherein these polymeric solutions maintain their improved viscosity and shear insensitively properties, when various ingredients are added to the thickened aqueous polymeric solutions to form a variety of diversified products.

A means for further improving the structuring of the gel formulations of the instant invention in order to obtain improved viscosity as well as G' and G" values is to form an aqueous polymeric solution of a crosslinked anionic polymer such as a crosslinked polyacrylic acid thickening agent at room temperature with mixing and subsequently with mixing L ir r 1- I i neutralizing the anionic groups such as the carboxylic acid groups by the addition of an excess basic material such as caustic soda to form an alkali metal neutralized crosslinked polyacrylic acid polymer. To the aqueous solution of the &lkali metal neutralized crosslinked polyacrylic acid containing excess caustic soda is added with mixing an amphoteric compound. The alkali metal crosslinked neutralized polyacrylic acid polymer in combination with the amphoteric compound provides improved G' and G' values as well as improved viscosification of the aqueous polymeric solution having a pH of 7 to 10 as compared to the use of the alkali S metal neutralized crosslinked polyacrylic acid alone as a viscosification agent. It is theorized that the improvement in viscosification results from the association of the amphoteric material and the alkali metal neutralized crosslinked polyacrylic acid polymer in the water, wherein the negative charges of the amphoteric compound and the negatively 0* 0 charged anionic groups of the polyacrylic acid are repulsive to each other thereby causing an uncoiling of the polymeric chain of the alkali metal neutralized crosslinked polyacrylic acid which provides a further building of the polymeric structure within the water. To the solution of the alkali metal neutralized crosslinked polyacrylic acid polymer, water and amphoteric compound detergent builder salts, silicates, surfacants, foam depressants and bleachants can be added without significantly damaging the polymeric structure to form a gel like automatic dishwashing composition. Other commercial and industrial compositions can be formed for a _II_ variety of applications such as toothpastes, creams or a toothpaste gels, cosmetics, fabric cleaners, shampoos, floor cleaners, cleaning paste, tile cleaners, thickened bleach compositions, ointments, oven cleaners, pharmaceutical suspensions, concentrated coal slurries, oil drilling muds, cleaning prestoppers and aqueous based paints. These compositions can be formulated by adding the appropriate chemicals to the aqueous polymeric solution of alkali metal neutralized polyacrylic acid polymer, caustic soda and the 0 amphoteric compound to form the desired composition. The o 0 polymeric aqueous solution of water, caustic soda, alkali metal neutralized polyacrylic acid polymer and the amphoteric S compound has a complex viscosity at room temperature at radians/second of 2 to 800 dynes second/sq.cm., more i.59: preferably 3 to 600 dynes second/sq. cm.. The polymeric solution comprises .05 to 4.0 weight more preferably 0.1 to 4.0 weight of an amphoteric compound, 0.1 to 4.0 weight more preferably 0.2 to 3.0 weight of an alkali metal neutralized crosslinked anionic polymer such as a metal 1 neutralized crosslinked polyacrylic polymer and water, wherein the aqueous polymeric solution has a G' value of at least dynes/sq. cm at a frequency of 10 radians/second, a G" value of at least 10 dynes/sq. cm at a frequency of 10 radians/second, a ratio of G'/G is less than 1 and CG is substantial constant over a frequency range of 0.01 to 50.0 radians/second.

If the polymeric solution has a G value of at least dynes/sq. cm. at a frequency of 10 radians/second and the G' valve is at least 10 dynes/sq. cm at a frequency of radians/second, wherein G' is substantially constant over a frequency range of 0.01 to 50 radians/second and a ratio of is less than 1 and a yield stress of at least 2 dynes/sq.cm., more preferably 2 to 1200 dynes/sq. cm., the polymeric solution will be a gel which can function as a suspension medium for a plurality of solid particles, immiscible liquid droplets or gaseous bubbles. The solid particles or liquid droplets or gaseous bubbles can be inorganic, organic or polymeric. The solid material liquid droplets or gas bubbles which are not soluble in the water o phase, should not decompose in an aqueous solution or react r with the anionic groups of the anionic polymer or the carboxylate groups. The concentration of the solid particles, liquid droplets or gaseous bubbles in the suspension medium is 0.1 to 70 weight percent, more preferably 1 to 50 weight Additionally, by the way of explanation; it is necessary to clearly emphasize that in order to minimize the rate and amount of sedimentation of solid particles that are insoluble in the suspension medium that the suspension medium should S.2, exhibit frequency independent moduli. For materials that exhibit frequency independence of the viscoelastic moduli these materials tend to exhibit a critical property known as the yield stress which prevents the sedimentation of insoluble particles from the suspension medium. It is also critical in the understanding of the data as presented in Example V of this invention that by linear viscoelastic gel it is meant that G is substantially constant over a strain range frequency of 0 to 50 percent. The minimum yield stress for the gel t u r n -r ;l i ~u necessary to suspend each of the solids, liquid or gaseous particles in the gel such that each particles will not settle from the gel is at least 2 dynes/sq. cm., more preperably 2 to 1200 dynes/sq.cm.

Illustrative of alkali metal neutralized anionic polymers contemplated within the scope of the instant invention beside polyacrylic and polymers such as the Carbopols are: sulfonated polymers containing a sulfonate functionality as defined in U.S. Patent Nos. 3,642,728; 4,608,425; .4,619,773; 4,626,285; .01 4,637,882; 4,640,945; 4,647,603; 4,710,555; 5,730,028; 4,963,032; 4,970,260 and 4,975,482, wherein these aforementioned patents are all hereby incorporated by reference. as well as polymers and monomers containing a carboxylic acid functionally as defined in U.S. Patent Nos.

4,612,332; 4,673,716; 4,694,046; 4,694,058; 4,709,759; 4,734,205, 4,780,517; 4,960,821 and 5,036,136, as well as copolymers containing a maleic anhydride functionality such as i Gantrez provided that these is a sufficient association j between the alkali metal neutralized salts of these polymers in the aforementioned patents and the Aluminum oxide to create a viscoelastic gel having the G' and properties as j defined herein.

The thickened aqueous polymeric solutions are made by neutralizing at room temperature with mixing an aqueous solution of the Carbopol resin with caustic soda such that to the resultant aqueous solution of the alkali metal neutralized Carbopol is added at room temperature with mixing an aqueous dispersion of aluminum oxide to form the thickened aqueous polymeric solution. A further enhancement of thickening can be achieved by the further addition of 0.02 to 1.0 weight percent of a fatty acid or a metal salt of a fatty acid.

Also contributing to the physical stability and low bottle residue of the invention compositions is the high potassium to sodium ion ratios in the range of 1:1 to 45:1, preferably 1:1 to 4:1, especially preferably from 1.05:1 to 3:1, for example 1.1:1, 1.2:1, 1.5:1, 2:1, or 2.5:1. At these ratios the solubility of the solid salt components, such as IoG detergent builder salts, bleach, alkali metal silicates, and o the like, is substantially increased since the presence of the potassium ions requires less water of hydration than the sodium ions, such that more water is available to dissolve these salt compounds. Therefore, all or nearly all of the normally solid components are present dissolved in the aqueous phase. Since there is none or only a very low percentage, i.e. less than preferably less than 3% by weight, of suspended solids present in the formulation there is no or only reduced tendency for undissolved particles to 2 settle out of the compositions causing, for example, formation of hard masses of particles, which could result in high bottle residues loss of product). Furthermore, any undissolved

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solids tend to be present in extremely small particle sizes, usually colloidal or sub-colloidal, such as 1 micron or less, thereby further reducing the tendency for the undissolved particles to settle.

A still further attribute of the invention compositions contributing to the overall product stability and low bottle 12 i residue is the high water absorption capacity of the crosslinked polyacrylic acid type thickening agent. As a result of this high water absorption capacity virtually all of the aqueous vehicle component is held tightly bound to the polymer !atrix. Therefore, there is no or substantially no free water present in the invention compositions. This absence of free water (as well as the cohesiveness of the composition) is manifested by the observation that when the composition is poured from a bottle onto a piece of water absorbent filter :110 paper virtually no water is absorbed onto the filter paper and, furthermore, the mass of the linear viscoelastic material poured onto the filter paper will retain its shape and structure until it is again subjected to a stress or strain.

As a result of the absence of unbound or free water, there is 31o: virtually no phase separatin between the aqueous phase and the polymeric matrix or dissolved solid particles. This characteristic is manifested by the fact that when the subject lit, compositions are subjected to centrifugation, e.g. at 1000 rpm for 30 minutes, there is no phase separation and the composition remains homogeneous.

However, it has also been discovered that linear 4 viscoelasticity and K/Na ratios in the above-mentioned range 4do not, by themselves, assure long term physical stability (as determined by phase separation). In order to maximize physical (phase) stability, the density of the composition should be controlled such that the bulk density of the liquid phase is approximately the same as the bulk density of the entire composition, including the polymeric thickening agent.

ML 1 This control and equalization Of the densities is achieved, according to the invention, by providing the composition with a bulk density of at least 1.28 g/cc, preferably at least 1.35 g/cc, up to 1.42 g/cc, preferably up to 1.40 g/cc.

Purthermore, to achieve these relatively high bulk densities, it is important to minimize the amount of air incorporated into the composition (a density of 1.42 g/cc is essentially equivalent to zero air content).

It has previously been found in connection with other *IAJ types of thickened aqueous liquid, automatic dishwasher detergent compositions that incorporation of finely divided ~air bubbles in amounts up to 8 to 10% by volume can function effectively to stabilize the composition against phase separation, but that to prevent agglomeration of or escape of the air bubbles it was important to incorporate certain surface active ingredients, especially higher fatty acids and S the salts thereof, such as stearic acid, behenic acid, palmitic acid, sodium stearate, aluminum stearate, and the like. These surface active agents apparently functioned by 2 0 forming an interfacial film at the bubble surface while also forming hydrogen bonds or contributing to the electrostatic attraction with the suspended particles, such that the air bubbles and attracted particles formed agglomerates of approximately the same density as the density of the continuous liquid phase.

Therefore, in a preferred embodiment of the present 1invention, stabilization of air bubbles which may become incorporated into the compositions during normal processing, if a i I i

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such as during various mixing steps, is avoided by post-adding the surface active ingredients, including fatty acid or fatty acid salt stabilizer, to the remainder of the composition, under low shear conditions using mixing devices designed to minimize cavitation and vortex formation.

As will be described in greater detail below the surface active ingredients present in the composition will include the main detergent surface active cleaning agent, and will also o, preferably include anti-foaming agent and higher fatty acid or *19. salt thereof as a physical stabilizer.

o 0 Exemplary of the cross-linked polyacrylic acid-type thickening agents are the products sold by B.F. Goodrich under their Carbopol trademark, especially Carbopol 941, which is the most ion-insensitive of this class of polymers, and o 8 0 Carbopol 940 and Carbopol 934. The Carbopol resins, also known as "Carbomer", are hydrophilic high molecular weight, cross-linked acrylic acid polymers having an average equivalent weight of 76, and the general structure illustrated by the following formula: H H r HO n.

Carbopol 941 has a molecular weight of 1,250,000; Carbopol I 940 a molecular weight of approximately 4,000,000 and Carbopol 934 a molecular weight of approximately 3,000,000. The Carbopol resins are cross-linked with polyalkenyl polyether, e.g. 1% of a polyallyl ether of sucrose having an average of i1 1 5.8 allyl groups for each molecule of sucrose. Further detailed information on the Carbopol resins is available from B.F. Goodrich, see, for example, the B.F. Goodrich catalog GC- 67, Carbopol® Water Soluble Resins.

While most favorable results have been achieved with Carbopol 941 polyacrylic resin, other lightly cross-linked polyacrylic acid-type thickening agents can also be used in the compositions of this invention. As used herein "polyacrylic acid-type" refers to water-soluble homopolymers of acrylic acid or methacrylic acid or water-dispersible or t t water-soluble salts, esters or amides thereof, or watert.1' soluble copolymers of these acids of their salts, esters or ameides with each other or with one or more other etylenically unsaturated monomers, such as, for example, styrene, maleic acid, maleic anhydride, 2-hydroxyethylacrylate, acrylonitrile, vinyl acetate, ethylene, propylene, and the like.

The homopolymers or copolymers are characterized by their 'I high molecular weight, in the range of from 500,000 to 10,000,000, preferably 500,000 to 5,000,000, especially from i 6 1,000,000 to 4,000,000, and by their water solubility, generally at least to an extent of up to 5% by weight, or more, in water at 25 0

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These thickening agents are used in their lightly crosslinked form wherein the cross-linking may be accomplished by means known in the polymer arts, as by irradiation, or, preferably, by the incorporation into the monomer mixt'ire to be polymerized of known chemical cross-linking monomeric agents, typically polyunsaturated diethylenically

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unsaturated) monomers, such as, for example, divinylbenzene, divinylether of diethylene glycol, N, N'-methylenebisacrylamide, polyalkenylpolyethers (such as described above), and the like. Typically, amounts of cross-linking agent to be incorporated in the final polymer may range from 0.01 to 1.5 percent, preferably from 0.05 to 1.2 percent, and especially, preferably from 0.1 to 0.9 percent, by weight of cross-linking agent to weight of total polymer.

Generally, those skilled in the art will recognize that the IlQ0 degree of cross-linking should be sufficient to impart some coiling of the otherwise generally linear polymeric compound while maintaining the cross-linked polymer at least water dispersible and highly water-swellable in an ionic aqueous medium. It is also understood that the water-swelling of the polymer which provides the desired thickening and viscous properties generally depends on one or two mechanisms, namely, conversion of the acid group containing polymers to the corresponding salts, e.g. sodium, generating negative charges Si- along the polymer backbone, thereby causing the coiled molecules to expand and thicken the aqueous solution; or by formation of hydrogen bonds, for example, between the carboxyl groups of the polymer and hydroxyl donor. The former mechanism is especially important in the present invention, and therefore, the preferred polyacrylic acid-type thickening agents will contain free carboxylic acid (COOH) groups along the polymer backbone. Also, it will be understood that the degree of cross-linking should not be so high as to render the cross-linked polymer completely insoluble or non-dispersible in water or inhibit or prevent the uncoiling of the polymer molecules in the presence of the ionic aqueous system.

The amount of the high molecular weight, cross-linked polyacrylic acid or other high molecular weight, hydrophilic tross-linked polyacrylic acid-type thickening agent to impart the desired rheological property of linear viscoelasticity will generally be in the range o2 from 0.1 to preferably from 0.2 to by weight, based on the weight of the composition, although the amount will depend on the particular cross-linking agent, ionic strength of the composition, hydroxyl donors and the like.

TheAcompositions of this invention must include sufficient amount of potassium ions and sodium ions to provide a weight ratio of K/Na of at least 1:1, preferably from 1:1 to 45:1, especially from 1:1 to 3:1, more preferably from 1.05:1 to 3:1, such as 1.5:1, or 2:1. When the K/Na ratio is less than 1 there is insufficient solubility of the normally solid ingredients whereas when the K/Na ratio is more than especially when it is greater than 3, the product becomes too liquid and phase separation begins to occur. When the K/Na ratio is more than 45, especially when it is greater than 3, the product becomes too liquid and phase separation begins to /i 1occur. When the K/Na ratios become much larger than 45, such as in all or mostly potassium formulation, the polymer thickener loses its absorption capacity and begins to salt out of the aqueous phase.

The potassium and sodium ions can be made present in the compositions as the alkali metal cation of the detergent [i builder salt(s), or alkali metal silicate or alkali metal hydroxide components of the compositions. The alkali metal cation may also be present in the compositions as a component of an ionic detergent, bleach or other ionizable salt compound additive, e.g. alkali metal carbonate. In determining the K/Na weight ratios all of these sources should be taken into consideration.

Specific examples of detergent builder salts include the polyphosphates, such as alkali metal pyrophosphate, alkali metal tripolyphosphate, alkali metal metaphosphate, and the like, for example, sodium or potassium tripolyphosphate (hydrated or anhydrous), tetrasodium or tetrapotassium pyrophosphate, sodium or potassium hexa-metaphosphate, trisodium or tripotassium orthophosphate and the like, sodium or potassium carbonate, sodium or potassium citrate, sodium or f potassium nitrilotriacetate, and the like. The phosphate builders, where not precluded due to local regulations, are preferred and mixtures of tetrapotassium pyrophosphate (TKPP) and sodium tripolyphosphate (NaTPP) (especially the hexahydrate) are especially preferred. Typical ratios of NaTPP to TKPP are from 2:1 to 1:8, especially from 1:1.1 to 1:6. 'The total amount of detergent builder salts is preferably from 5 to 35% by weight, more preferably from to 35%, especially from 18 to 30% by weight of the composition.

Other useful low molecular weight noncrosslinked polymers are Acusol"640D provided by Rohm Haas; Norasol QR1014 from Norsohaas having a GPC molecular weight of 10r000.

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8 The linear viscoelastic compositions of this invention may, and preferably will, contain a small, but stabilizing effective amount of a long chain fatty acid or monovalent or polyvalent salt thereof. Although the manner by which the katty acid or salt contributes to the rheology and stability of the composition has not been fully elucidated it is hypothesized that it may function as a hydrogen bonding agent or cross-linking agent for the polymeric thickener.

The preferred long chain fatty acids are the higher aliphatic fatty acids having from 8 to 22 carbon atoms, more 0 preferably from 10 to 20 carbon atoms, and especially 0 0 2o preferably from 12 to 18 carbon atoms, and especially preferably from 12 to 18 carbon atoms, inclusive of the carbon atom of the carboxyl group of the fatty acid. The o 5: aliphatic radical may be satuirated or unsaturated and may be °I straight or branched. Straight chain saturated fatty acids are preferred. Mixtures of fatty acids may be used, such as those derived from natural sources, such as tallow fatty acid, coco fatty acid, soya fatty acid, mixtures of these acids, etc. Stearic acid and mixed fatty acids, e.g. stearic A acid/palmitic acid, are preferred.

When the free acid form of the fatty acid is used directly it will generally associate with the potassium and sodium ions in the aqueous phase to form the corresponding alkali metal fatty acid soap. However, the fatty acid salts may be directly added to the composition as sodium salt or potassium salt, or as a polyvalent metal salt, although the 1 alkali metal salts of the fatty acids ara preferred fatty acid salts.

The preferred polyvalent metals are the di- and trivalent metals of Groups IIA, IIB and IIIB, such as magnesium, calcium, aluminum and zinc, although other polyvalent metals, including those of Groups IIIA, IVA, VA, IB, IVB, VB VIB, VIIB and VIII of the Periodic Table of the Elements can also be used. Specific examples of such other polyvalent metals include Ti, Zr, V, Nb, Mn, Fe, Co, Ni, Cd, Sn, Sb, Bi, etc.

.1Q. Generally, the metals may be present in the divalent to pentavalent state. Preferably the metal salts are used in o: their higher oxidation states. Naturally, for use in automatic dishwashers, as well as any other applications where the invention composition will or may come in 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 alkali metal and calcium and 42'0 magnesium salts are especially higher preferred as generally safe food additives.

The amount of the fatty acid or fatty acid salt B .stabilizer to achieve the desired enhancement of physical stability will depend on such factors as the nature of the fatty acid or its salt, the nature and amount of the thickening agent, detergent active compound, inorganic salts, other ingredients, as well as the anticipated storage and shipping conditions.

21 J- m Genercily, however, amourzs of the fatty acid or fatty acid salt stabilizing agents in the range of from 0.02 to 2%, preferably 0.04 to more preferably from 0.06 to 0.8%, especially preferably from 0.08 to provide a long term tability and absence of phase separation upon standing or during transport at both low and elevated temperatures as are required for a commercially acceptable product.

Depending on the amounts, proportions and types of fatty acid physical stabilizers and polyacrylic acid-type thickening 1 agents, the addition of the fatty acid or salt not only increases physical stability but also provides a simultaneous increase in apparent viscosity. Amounts of fatty acid or salt to polymeric thickening agent in the range of from 0.08-0.4 weight percent fatty acid salt and from 0.4-1.5 weight percent polymeric thickening agent are usually sufficient to provide these simultaneous benefits and, therefore, the use of these ingredients in these amounts is most preferred.

In order to achieve the desired benefit from the fatty 'At, acid or fatty acid salt stabilizer, without stabilization of excess incorporated air bubbles and consequent excessive lowering of the product bulk density, the fatty acid or salt should be post-added to the formulation, preferably together with the other surface active ingredients, including detergent active compound and anti-foaming agent, when present. These surface active ingredients are preferably added as an emulsion in water wherein the emulsified oily or fatty materials are finely and homogeneously dispersed throughout the aqueous phase. To achieve the desired fine emulsification of the L i- R fatty acid or fatty acid salt and other surface active ingredients, it is usually necessary to heat the emulsion (or preheat the water) to an elevated temperature near the melting temperature of the fatty acid or its salt. For example, for 6tearic acid having a melting point of 68 0 C-69 0 C, a temperature in the range of between 50 0 C and 70 0 C will be used. For lauric acid an elevated temperature of 35 0 C to 50 0 C can be used. Apparently, at these elevated temperatures the fatty acid or salt and other surface active ingredients can be more "l0. readily and uniformly dispersed (emulsified) in the form of o o o, o o fine droplets throughout the composition.

o 0 In contrast, as will be shown in the examples which S follow, if the fatty acid is simply post-added at ambient temperature, the composition is not linear viscoelastic as L defined above and the stability of the composition is clearly inferior.

Foam inhibition is important to increase dishwasher machine efficiency and minimize destabilizing effects which might occur due to the presence of excess foam within the washer during use. Foam may be reduce 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 the builder salts such as NaTPP which has a water softening effect, may aid in providing a degree of foam inhibition.

However, it is generally preferred to include a chlorine 23 bleach stable foam depressant or inhibitor. Particularly effective are the alkyl phosphoric acid esters of the formula 0

II

HO-P-R

II

OR

and especially the alkyl acid phosphate esters of the formula 0 11

HO-P--OR

II

OR

In the above formulas, one or both R groups in each type of ester may represent independently a C 12

-C

20 alkyl or ethoxylated alkyl group. The ethoxylated derivatives of each type of ester, for example, the condensation products of one mole of ester with from 1 to 10 moles, preferably 2 to 6 moles, more preferably 3 or 4 moles, ethylene oxide can also be used.

S Some examples of the foregoing are commercially available, such as the products SAP from Hooker and LPKN-158 from Knapsack. Mixtures of the two types, or any other chlorine bleach stable types, or mixtures of mono- and di-esters of the same type, may be employed. Especially preferred is a mixture of mono- and di-C, 6 -C,8 alkyl acid phosphate esters such as monostearyl/distearyl acid phosphates 1.2/1, and the 3 to 4 mole ethylene oxide condensates thereof. When employed, proportions of 0.05 to 1.5 weight percent, preferably 0.1 to weight percent, of foam depressant in the composition is typical, the weight ratio of detergent active component to foam depressant generally ranging from 10:1 to 1:1 and preferably 5:1 to i:1. Other defoamers which may be used 24

F-

include, for example, the known silicones, such as available from Dow Chemicals. In addition, it is an advantageous feature of this invention that many of the stabilizing salts, such as the stearate salts, for example, aluminum stearate, When included, are also effective as foam killers.

Although any chlorine bleach compound may be employed in the compositions of this invention, such as dichloroisocyanurate, dichloro-dimethyl hydantoin, or chlorinated TSP, alkali metal or alkaline earth metal, e.g. potassium, lithium, magnesium and especially sodium, hypochlorite is preferred.

The composition should contain sufficient amount of chlorine bleach compound to provide 0.2 to 4.0% by weight of available S chlorine, as determined, for example by acidification of 100 parts of the composition with excess hydrochloric acid. A 5 solution containing 0.2 to 4.0% by weight of sodium e hypochlorite contains or provides roughly the same percentage of available chlorine. 0.8 to 1.6% by weight of available chlorine is especially preferred. For example, sodium hypochlorite (NaOCL) solution of from 11 to 13v available 0" chlorine in amounts of 3 to 20%, preferably 7 to 12%, can'be advantageously used.

Detergent active material useful herein should be stable in the presence of chlorine bleach, especially hypochlorite bleach, and for this purpose 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. Particularly preferred surfactants herein are the linear or branched alkali c i i metal mono- and/or di-(C 8

-C

1 4 alkyl diphenyl oxide mono- and/or di-sulphates, 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 organic anionic, non-soap surfactants include the primary alkylsulphates, alkylsulphonates, alkylarylsulphonates and sec.alkylsulphates. Examples include sodium C 10 -Cig alkylsulphates such as sodium dodecylsulphate and sodium tallow alcoholsulphate; sodium C 10

-C

18 alkanesulphonates such as sodium S hexadecyl-l-sulphonate and sodium C 2

-C

18 alkylbenzenesulphonates such as sodium dodecylbenzenesylphonates. The corresponding potassium salts may also be employed.

As other suitable surfactants or detergents, the amine oxide surfactants are typically of the structure R 2 RINO, in which each R represents a lower alkyl group, for instance, methyl, and R 1 represents a long chain alkyl group having from 8 to 22 carbon atoms, for instance a lauryl, myristyl, palmityl or cetyl group. Instead of an amine oxide, a corresponding surfactant phosphine oxide R 2 RIPO or sulphoxide RR'SO can be employed. Betaine surfactants are typically of the structure RR,N+R"COO-, in which each R represents a lower alkylene group having from 1 to 5 carbon atoms. Specific examples of these surfactants include lauryl-dimethylamine oxide, myristyl-dimethylamine oxide, myristyl-dimethylamine oxide, the corresponding phosphine oxides and sulphoxides, and the corresponding betaines, including dodecyldimethylammonium acetate, 'tetradecyldiethylammonium pentanoate, hexadecyldimethylammonium hexanoate and the like. For biodegradability, the alkyl groups in these surfactants should be linear, and such compounds are preferred.

Surfactants of the foregoing type, all well known in the art, are described, for example, in U.S. Patents 3,985,668 and 4,271,030. If chlorine bleach is not used than any of the well known low-foaming nonionic surfactants such as alkoxylated fatty alcohols, e.g. mixed.ethylene oxidepropylene oxide condensates of C 8

-C

22 fatty alcohols can also be used.

The chlorine bleach stable, water dispersible organic detergent-active material (surfactant) will normally be present in the composition in minor amounts, generally 1% by weight of the composition in minor amounts, generally 1% by weight of the composition, although smaller or larger amounts, such as up to such as from 0.1 to preferably form 0.3 or 0.4 to 2% by weight of the composition, may be used.

Alkali metal potassium or sodium) silicate, which provides alkalinity and protection of hard surfaces, such as S fine china glaze and pattern, is generally employed in an amount ranging from 5 to 20 weight percent, preferably 5 to weight percent, more preferably 8 to 12% in the composition. The sodium or potassium silicate is generally added in the form of an aqueous solution, preferably having Na2O:SiO 2 or K 2 0:SiO, ratio of 1:1.3 to 1:2.8, especially preferably 1:2.0 to 1:2.6. At this point, it should be mentioned that many of the other components of this 27 k I: composition, especially alkali metal hydroxide and bleach, are also often added in the form of a preliminary prepared aqueous dispersion or solution.

In addition to the detergent active surfactant, foam inhibitor, alkali metal silicate corrosion inhibitor, and detergent builder salts, which all contribute to the cleaning performance, it is also known that the effectiveness of the liquid automatic dishwasher detergent compositions is related to the alkalinity, and particularly to moderate to high 010 alkalinity levels. Accordingly, the compositions of this invention will have pH values of at least 9.5, preferably at least 11 to as high as 14, generally up to 13 or more, and, when added to the aqueous wash bath at a typical concentration level of 10 grams per liter, will provide a pH in the wash bath of at least 9, preferably at least 10, such as 10.5, o: 11, 11.5 or 12 or more.

The alkalinity will be achieved, in part by the alkali metal ions contributed by the alkali metal detergent builder salts, e.g. sodium tripolyphosphate, tetrapotassium pyrophosphate, and alkali metal silicate, however, it is usually necessary to include alkali metal hydroxide, e.g. NaOH or KOH, to achieve the desired high alkalinity. Amounts of alkali metal hydroxide in the range of (on an active basis) of from 0.5 to preferably from 1 to more preferably from 1.2 to by weight of the composition will be sufficient to achieve the desired pH level and/or to adjust the K/Na weight ratio.

r t I II 4 I Ir t 4 rir .44 4~ r 44 '2 2 Other alkali metal salts, such as alkali metal carbonate may also be present in the compositions in minor amounts, for example from 0 to preferably 0 to by weight of the composition.

Other conventional ingredients may be included in these compositions in small amounts, generally less than 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. Especially preferred for coloring are the chlorinated phythalocyanines and polysuphides of aluminosilicate which provide, respectively, pleasing green and blue tints. Ti02 may be employed for whitening or neutralizing off-shades.

Although for the reasons previously discussed excessive air bubbles are not often desirable in the invention compositions, depending on the amounts of dissolved solids and liquid phase densities, incorporation of small amounts of finely divided air bubbles, generally up to 10% by volume, preferably up to 4% by volume, more preferably up to 2% by volume, can be incorporated to adjust the bulk density to approximate liquid phase density. The incorporated air bubbles should be finely divided, such as up to 100 microns in diameter, preferably from 20 to 40 microns in diameter, to assure maximum stability. Although air is the preferred gaseous medium for adjusting densities to improve physical

I-

stability of the composition other inert gases can also be used, such as nitrogen, carbon dioxide, helium, oxygen, etc.

The amount of water contained in these compositions should, of course, be neither so high as to produce unduly low riscosity and fluidity, nor so low as to produce unduly high viscosity and low flowability, linear viscoelastic properties in either case being diminished or destroyed by increasing tan 1. Such amount is readily determined by routine experimentation in any particular instance, generally ranging from 30 to 75 weight percent, preferably 35 to 65 weight gI: percent. The water should also be preferably deionized or I softened.

4eeyeA+ COmpos lolns o 0 4F e The manner of formulating theA invention eempesitieons is also important. As discussed above, the order of mixing the ingredients as well as the manner in which the the mixing is performed will generally have a significant effect on the properties of the composition, and in particular on product density (by incorporation and stabilization of more or less air) and physical stability phase separation). Thus, 20 i according to the preferred practice of this invention the compositions are prepared by first forming a dispersion of the Aj polyacrylic acid-type thickener in water under moderate to d' high shear conditions, neutralizing the dissolved polymer to cause gelation, and then introducing, while continuing mixing, the detergent builder salts, alkali metal dilicates, chlorine bleach compound and remaining detergent additives, including any previously unused alkali metal hydroxide, if any, other than the surface-active compounds. All of the additional ingredients can be added simultaneously or sequentially.

Preferably, the ingredients are added sequentially, although it is not necessary to complete the addition of one ingredient before beginning to add the next ingredient. Furthermore, one 6r more of these ingredients can be divided into portions and added at different times. These mixing steps should also be performed under moderate to high shear rates to achieve complete and uniform mixing. These mixing steps may be carried out at room temperature, although the polymer thickener neutralization (gelation) is usually exothermic.

09*, 0 00 oo 4 The composition may be allowed to age, if necessary, to cause o" 00 0 00 dissolved or dispersed air to dissipate out of the composition.

The remaining surface active ingredients, including the anti-foaming agent, organic detergent compound, and fatty acid or fatty acid salt stabilizer is post-added to the previously formed mixture in the form of an aqueous emulsion (using from 1 to 10%, preferably from 2 to 4% of the total water added to the composition other than water added as carrier for other 120 ingredients or water of hydration) which is pre-heated to a temperature in the range of from Tm+5 to Tm-20, preferably from TM to TM-10, where Tm is the melting point temperature of the fatty acid or fatty acid salt. For the preferred stearic acid stabilizer the heating temperature is in the range of 50 0 C to 70C. However, if care is taken to avoid excessive air bubble incorporation during the gelatin step or during the mixing of the detergent builder salts and other additives, for example, by operating under vacuum, or using 31 low shearing conditions, or special mixing operatatus, etc., the order of addition of the surface active ingredients should be less important.

If 4 re- inv on, In accordance with an especially preferred embodiment/ a 4he- thickened linear viscoelastic aqueous automatic dishwasher I is provde detergent compositionA f'this iventio includco, on a weight basis: 10 to 35%, preferably 15 to 30%, alkali metal polyphosphate detergent builder; 5 to 15, preferably 8 to 12%, alkali metal silicate; 1 to preferably 1.2 to alkali metal hydroxide; 0.1 to preferably 0.5 to chlorine bleach stable, water-dispersible, low-foaming organic detergent active material, preferably non-soap anionic detergent; 0.05 to preferably 0.1 to chlorine bleach stable foam depressant; chlorine bleach compound in an amount to provide 0.2 to preferably 0.8 to of available chlorine; high molecular weight hydrophilic cross-linked polyacrylic acid thickening agent in an amount to provide a linear viscoelasticity to the formulation, preferably from 0.4 to more preferably from 0.4 to a long chain fatty acid or a metal salt of a long chain fatty acid in an amount effective to increase the physical stability of the compositions, preferably from 0.08 to more preferably from 0.1 to and ©I.f .32

-E-

J balance water, preferably from 30 to 75%, more preferably from 35 to 65%; and wherein in the alkali metal polyphosphate includes a mixture of from 5 to preferably from 12 to 22% of tetrapotassium pyrophosphate, nd from 0 to 20%, preferably from 3 to 18% of sodium tripolyphosphate, and wherein in the entire composition the ratio, by weight, of potassium ions to sodium ions is from 1.05/1 to 3/1, preferably from 1.1/1 to 2.5/1, the compositions having an amount of air incorporated therein such 1Q that the bulk density of the composition is from 1.32 to 1.42 g/cc, preferably from 1.35 to 1.40 g/cc.

TheAcompositions will be supplied to the consumer in suitable dispenser containers preferably formed of molded plastic, especially polyolefin plastic, and most preferably o polyethylene, for which the invention compositions appear to have particularly favorable slip characteristics. In addition to their linear viscoelastic character, the compositions of this invention may also be characterized as pseudoplastic gels (non-thixotropic) which are typically near the borderline between liquid and solid viscoelastic gel, depending, for example, on the amount of the polymeric thickener. The invention compositions can be readily poured from their containers without any shaking or squeezing, although squeezable containers are often convenient and accepted by the consumer for gel-like products.

The liquid aqueous linear viscoelastic automatic 2i dishwasher compositions of this invention are readily employed in known manner for washing dishes, other kitchen utensils and Ze1 33 1 ~ij the like in an automatic dishwasher, provided with a suitable detergent dispenser, in an aqueous wash bath containing an effective amount of the composition, generally sufficient to fill or partially fill the automatic dispenser cup of the Particular machine being used.

The invention also provides a metho for cleaning dishware in an automatic dishwashing machine with an aqueous wash bath containing an effective amount of the liquid linear viscoelastic automatic dishwasher detergent composition as described above. The composition can be readily poured from 00 0r the polyethylene container with little or no squeezing or o shaking into the dispensing cup of the automatic dishwashing machine and will be sufficiently viscous and cohesive 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 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 the amounts and proportions referred to herein are by weight of the composition unless otherwise indicated.

Example 1 The following formulations A-K were prepared as described below: 4- 0404 4 40 0 400 040 4 404 44 4 INGREDIENT A B C D E F G H I J K

/FORMULATION

DEIONIZED WATER BAL. BAL. BAL. BAL. BAL. BAL. BAL. BAL. BAL BAL. BAL.

CARBOPOL 941 0.9 0.9 0.9 0.9 1 0.9 0.9 1.5 0.9 NaOH 2.4 2.4 2.4 2.4 3.5 3.5 2.4 2.4 2.4 2.4 KOH 2.4 TKPP 15 15 15 20 20 20 28 28 15 20 TPP 13 13 12 7.5 7.5 7.5 13 7.5 13 HEXAHYDRATE, Na Na SILICATE 21 21 21 21 17 17 21 21 21 21 (1:2.3) K SILICATE 34 (1:2.3) LPKN 3.2 3.2 3.2 3. 2 3.2 3.2 3.2 3.2 3.2 DOWFAX 3B2 1 1 1 1 1 1 1 1 1 1 1 FA'TTY ACID 2 0.1 0.1 0.1 0.1 0.1 0.1 1 0.1 0.1 BLEACH (13.0% 7.5 7.5 7.5 7.5 9.1 9.1 7.5 7.5 7.5 7.5 9

CL)

AIR* Vol.%) <2.0 <2.0 <2.0 <2.0 <2.0 >2.0 <2.0 >2.0 >2.0 <2.0 FRAGRANCE 0.17 K/Na RATIO 1.12 1.12 1.16 1.89 1.95 1.95 4.16 45.15 1.89 m mi-i 0 0 40 a A B C ID BE F G IH I J K DENSITY (g/cc) 1.37 1.37 1.35 1.37 1.36 1.37 1.37 1.37 RHEOGRAM Fig.1 Fig.2 Fig.3 Fig.4 Fig.6 Fig.7 Fig.5 Fig.8 STABILITY 0.0 0.0 0.0 0.0 >10.0 >10.0 0.0 >20.0 >5.0 0.0

RESULTS

ROOM TEMP.

8 u_=KS STABILITY 0.0 0.0 0.0 0.0 1>10.0 >10.0 0.0 >20.0 >5.0 0.0

RESUITS

100 0 F, 6 WEEKS 1. Carbopol 940 2. Emersol 132 (Mixture of stearic and palmitic acid 1:1 ratio 3. All the formulations are aerated to a certain degree depending upon the shear condition employed for the preparation, typically the volume of air does not exceed 7-8% by volume, the preferred degree of aeration by volume) resulting in the indicated densities; the air bubbles average between 20 and 60 microns in diameter.

41 0 Formulations A, B, C, D, E, G, J, and K are prepared by first forming a uniform dispersion of the Carbopol 941 or 940 thickener in 97% of the water (balance). The Carbopol is slowly added to deionized water at room temperature using a f iixer equipped with a premier blade, with agitation set at a medium shear rate, as recommended by the manufacturer. The dispersion is then neutralized by addition, under mixing, of the caustic soda (50% NaOH or KOH) component to form a thickened product of gel-like consistency.

To the resulting gelled dispersion the silicate, tetrapotassium pyrophosphate (TKPP), sodium tripolyphosphate TP(TPP, Na) and bleach, are added sequentially, in the order stated, with the mixing continued at mediu shear.

Separately, an emulsion of the phosphate anti-foaming agent (LPKN), stearic acid/palmitic acid mixture and detergent *4 V (Dowfax 3B2) is prepared by adding these ingredients to the remaining 3% of water (balance) and heating the resulting mixture to a temperature in the range of 50 0 C to 70 0

C.

This heated emulsion is then added to the previously prepared gelled dispersion under low shear conditions, such that a vortex is not formed.

The remaining formulations F, H and I are prepared in essentially the same manner as described above except that the heated emulsion of LPKN, stearic acid and Dowfax 3B2 is directly added to the neutralized Carbopol dispersion prior to the addition of the remaining ingredients. As a result, formulations F, H and I, have higher levels of incorporated air and densities below 1.30 g/cc.

i' The rheograms for the formulations A, C, D, G and J are shown in figures 1-5, respectively, and rheograms for formulations H, I and K are shown in figures 6, 7 and 8 respectively.

These rheograms are obtained with the System 4 Rheometer from Rheometrics equipped with a Fluid Servo with a 100 gramscentimeter torque transducer and a 50 millimeter parallel plate geometry having an 0.8 millimeter gap between plates.

All measurements are made at room temperature (25 0 C+1 0 C) in a So. humidity chamber after a 5 minute or 10 minute holding period i: "on of the sample in the gap. The measurements are made by S applying a frequency of 10 radians per second.

All of the composition formulations A, B, C, D, G and J according to the preferred embodiment of the invention which include Carbopol 941 and stearic acid exhibit linear ce viscoelasticity as seen from the rheograms of figure Formulation E which includes Carbopol 941 but not stearic acid 0, 0 showed no phase separation at either room temperature or 100°F after 3 weeks, but exhibited 10% phase separation after 8 0 i a a weeks at room temperature and after only 6 weeks at 100 0

F.

Formulation K, containing Carbopol 940 in place of Carbopol 941, as seen from the rheogram in figure 8, exhibits substantial linearity over the strain range of from 2% to at 1% strain-G' at 50% strain 500 dynes/sq.cm.) although tan at a strain above Example 2 This example demonstrates the importance of the order of addition of the surface active component premix to the remainder of the composition on product density and stability.

The following formulations are prepared by methods A and Ingredient Water, deionized Balance Carbopol 941 NaOH 2.4 Na Silicate 21 TKPP TPP, Na 13 Bleach LPKN 0.16 Stearic Acid 0.1 Dowfax 3B2 1 I *Method A: The Carbopol 941 is dispersed, under medium shear rate, using a premier blade mixer, in deionized water at ambient temperature. The NaOH is added, under mixing, to neutralize and gel the Carbopol 941 dispersion. To the thickened mixture the following ingredients are added sequentially while the stirring is continued: sodium silicate, TKPP, TPP, and bleach.

i Separately, an emulsion is prepared by adding the Dowfax I 3B2, stearic acid and LPKN to water while mixing at moderate shear and heating the mixture to 65 0 C to finely disperse the emulsified surface active ingredients in the water phase.

This emulsion premix is then slowly added to the Carbopol dispersion while mixing under low shear conditions without forming a vortex. The results are shown below.

Method B: Method A is repeated except that the heated emulsion premix is added to the neutralized Carbopol 941 dispersion before the sodium stearate, TKPP, TPP, and bleach. The results are also shown below.

Method A Method B Density (g/cc) 1.38 1.30 Stability (RT-8 weeks) 0.00% 7.00% Rheogram Fig. 9 From the rheograms of figures 9 and 10 it is seen that both products are linear viscoelastic although the elastic and viscous moduli G' and G" are higher for Method A than for Method B.

From the results it is seen that early addition of the surface active ingredients to the Carbopol gel significantly increases the degree of aeration and lowers the bulk density of the final product. Since the bulk density is lower than the density of the continuous liquid phase, the liquid phase undergoes inverse separation (a clear liquid phase forms on the bottom of the composition). This process of inverse separation appears to be kinetically controlled and will occur faster as the density of the product becomes lower.

Exampie 3 S 25 This example shows the importance of the temperature at which the premixed surfactant emulsion is prepared.

Two formulations,, L and M, having the same composition as in Example 2 except that the amount of stearic acid was increased from 0.1% to 0.2% are prepared as shown in Method A for formulation L and by the following Method C for formulation M.

Method C The procedure of Method A is repeated in all details 'xcept that emulsion premix of the surface active ingredients is prepared at room temperature and is not heated before being post-added to the thickened Carbopol dispersion containing silicate, builders and bleach. The rheograms for formulations L and M are shown in figures 11 and 12; respectively. From these rheograms it is seen that formulation L is linear viscoelastic in both G' and G" whereas formulation M is nono linear viscoelastic particularly for elastic modulus G' at a 1% strain-G' at 30'% strain 500 dynes/cm 2 and also for G" (G" at 1% strain-G" at 30% strain 300 dynes/cm 2 -Formulation L remains stable after storage at RT and 100°F for at least 6 weeks whereas formulation M undergoes phase separation.

Comparative Example 1 The following formulation is prepared without any potassium salts: Weight Water Balance Carbopol 941 0.2 NaOH 2.4 TPP, Na 21.0 Na Silicate 17.24 SBleach 7.13 Stearic Acid 0.1 LPKN 3.2 Dowfax 3B2 0.8 Soda Ash Acrysol LMW 45-N i 1 The procedure used is analogous to Method A of Example 2 with the soda ash and Acrysol LMW 45-N (low molecular weight polyacrylate polymer) being added before and after, respectively, the silicate, TPP and bleach, to the thickened tarbopol 941 dispersion, followed by addition to the heated surface active emulsion premix. The rheogram is shown in figure 13 and is non-linear with (tan6 1 over the range of strain of from 5% to Example 4 Formulations A, B, C, D and K according to this invention o oo and comparative formulations F and a commercial liquid a: automatic dishwasher detergent product as shown in Table 1 above were subjected to a bottle residue test using a standard polyethylene 28 ounce bottle as used for current commercial liquid dishwasher detergent bottle.

Six bottles are filled with the respective samples and i o the product is dispensed, with a minimum of force, in 80 gram S°.dosages, with a 2 minute rest period between dosages, until flow stops. At this point, the bottle was vigorously shaken S° to try to expel additional product.

A ,The amount of product remaining in the bottle is measured as a percentage of the total product originally filled in the bottle. The results are shown below.

42 Bottle Residue

I

I

I

4 Formulation

A

B

C

D

K

Com mercial Product *The sample separates upon aging Example V The following formulas (A to the following procedure: K were prepared according Residue 8 A B C D E Carbopol 614 1.0 1.0 1.0 0.75 10.75 NaOH 0.5 0.5 0.5 0.375 0.375 Alumina 0.2 1.6 0.5 (Dispal T23) Water 98.5 98.3 96.9 98.375 97.375 Figure Nos. 14,15 16,17 18,19 20,21 22,23 F G H I J K Carbopol 614 0.5 0.5 0.5 1.0 0.75 0.

NaOH 0.25 0.25 0.25 0.5 0.375 0.25 Stearic A-cid .01 Alumina 0.5 2.0 1.0 1.0 2.5 (Dispal T23) Water 98.75 97.25 98.25 97.5 96.375 98.74 Figure Nos. 24,25 26,27 28,29 30,31 32 33,34 0 0

IC

The Carbopol polymer was added to water at 750 80 0 C with mixing. To the solution of the Carbopol polymer and water was added with mixing the sodium hydroxide to neutralize the Carbopol polymer so that the solution has a pH of 7 to the dispersion of the alumina (Dispol T23) was added with mixing to the solution of water and neutralized Carbopol polymer to form formulas (A K The polymer solutions were tested on the System 4 Rheometer as in Example 1. The Brookfield viscosities were run at room temperature using a #4 spindle at 20 rpms. Rheograms Figure 14-24) depict the G' and G" for formulas A-K, wherein for each formula a plot of G' and G" is illustrated.

*4 t e

T

Soe o

Claims (6)

1. 4. 4 A a 4 -C 4 125 1. A polymeric composition which comprises: 0.5 to 14 weight percent of a polymeric &omplex which comprises an alkali metal neutralized anionic polymer having a molecular weight of 100,000 to 10,000,000 MeWd oxi*de wherein said anionic polymer is complexed with aA structuring agent, a weight ratio of said alkali metal neutralized anionic polymer to said structuring agent being 1:10 to 10:1; and water, wherin the polymeric composition has a Brookfield viscosity measured with a #6 spindle at room temperature and 20 rpms of 700 cps to 27,000 cps. 2. The polymeric composition of Claim 1 wherein -sai- structuring agent metal oxide eempe is an amphoteric metal compound having a particle size of 0.5 to 40 microns. 3. The composition of Claim 2, wherein said anionic polymer has an anionic group selected from the group consisting of alkali metal neutralized carboxylic groups and alkali metal neutralized sulfonated groups and said structuring agent is an aluminum oxide. 4. The composition of Claim 3, wherein said anionic polymer is an alkali metal neutralized polyacrylic acid polymer. The composition of Claim 4, wherein said alkali metal neutralized polyacrylic acid polymer is crosslinked.
2. 6. The composition of Claim 1, wherein said structuring agent is a mixture of Mgo/aluminum oxide.
3. 7. The composition of Claim 1, further including at least one additive selected from the group consisting essentially of at least on an alkali metal detergent builder salt, a surface active compound, a foam depressant, a chlorine tontaining compound and an alkali metal silicate and mixtures thereof.
4. 8. The composition of Claim 1 further including at least one additive selected from the group consisting of a polishing agent, a bodying or gelling agent, a humectant, a flavoring agent, and an anti-calculus agent. a09. The composition of Claim 1 further including 0.1 to 0 10 weight percent of an electrolyte.
5. 0010. A polymeric solution having a complex viscosity at aroom temperature at 10 radians/second of 2 to 800 dynes seconds/sq.cm. which comprises: 0(a) 0.1 to 4.0 weight precent of an alkali metal 00 0 neutralized anionic polymer; taiL al'mtlium oc'e 0.1 to 4.0 weight percent of,-a- structuring agent; and j water, wherein said polymeric solution has a G' value of at least 80 dynes/sq. cm at a frequency of radiaris/second and a G" of at least 10 dynes/sq. cm at a fequency of 10 radi.ans/second and a ratio of is less than 1 and GI is substantially constant at frequency of between 0.01 to 50.0 radians/second.
6. 11. A viscoelastic gel composition having a G/ of at least 80 dynes/sq. cm. at a frequency of 10 radians/second, a G' of at least 10 dynes/sq. cm at a frequency of N __47 r radians/second, a ratio of is less than 1, G is substantially constant at a frequency between 0.01 to 50.0 radians/second and a yield stress of at least 2 to 1200 dynes/cm 2 which comprises: a suspension medium comprising: 0.1 to 4.0 weight of an alkali metal neutralized anionic polymer; oaA aluMtn'tvm Oio(e 0.01 to 4.0 weight percent of a-structuring agent and water; and a plurality of solid or liquid particles being suspended in said suspension medium such that said solid o 'V 0° 0 particles do not settle from said suspension medium with a period of seven days. Dated this 13th day of May 1992 COLGATE-PALMOLIVE COMPANY Patent Attorneys for the Applicant .It F.B. RICE CO t t ES ABSTRACT OF THE DISCLOSURE Automatic dishwasher detergent composition is formulated as a linear viscoelastic, pseudoplastic, gel-like aqueous product of exceptionally good physical stability, low bottle residue, low cup leakage, and improved cleaning performance, Linear viscoelasticity and pseudoplastic behavior is attributed by incorporation of cross-linked high molecular weight polyacrylic acid type thickener. Potassium to sodium weight ratios of at least 1/1 minimize amount of undissolved solid particles to further contribute to stability and pourability. Control of incorporated air bubbles functions to provide the product with a bulk density of 1.28 to 1.40 g/cc which roughly corresponds to the density of the liquid phase. D e Stearic acid or other fatty acid or salt further improve physical stability. 1i