CA1160134A - Abrasive-containing liquid detergent composition - Google Patents

Abstract

ABRASIVE-CONTAINING LIQUID DETERGENT COMPOSITION
Abstract Abrasive liquid detergent compositions containing an anionic surfactant, a nonionic surfactant and a water-insoluble abrasive are disclosed.

Description

.34 ABRASIVE-CONTAIN~NG LIQ~ID DETERGENT COMPOSITION

Background The invention relates to a high sudsing liquid deter-gent containing specified amounts and types of insoluble abrasives especially useful in the washing of tableware, kitchenware and other hard surfaces.
The use of abrasives in powdered scouring cleansers is well known. Scouring cleansers generally contain a relatively high level of abrasive. When such scouring cleansers are used as adjuncts in the dishwashing process such products provide abrading power to make the removal of cooked, burnt, or dried-on foods on kitchenware easier and more convenient. Recently, liquid scouring cleansers containing water-insoluble abrasives have become available.
Such liquid compositions are disclosed in U.S. Patents 3,149,078; 3,210,285; 3,210,286; 3,214,380; 3,579,456;
3,623,990; 3,677,954; 3,813,349; 3,966,432; and 4,129~527;
and British Patents 1,384,244 and 1,534,680. The use of scouring cleansers, however, is normally in addition to a specific dishwashing product, one product being required for removal of non-sticking soils, especially fats and oils, and a second product being reqired for scouring purposes. Canadian Patent 1,048,365 discloses granular detergent compositions suitable for dishwashing containing 20% to 35% surfactant and 5% to 20% of abrasive material haviny a particle diameter in the range of 200 to 850 microns. Copending commonly assigned Canadian Serial No.
343,185 of Mitchell et al filed January 7, 1980, discloses liquid detergent compositions suitable for dishwashing containing insoluble abrasives and detergency builders.
Copending commonly assigned Canadian Serial No. 354,964 of Tuthill et al filed June 27, 1980 discloses abrasive-containing liquid detergent compositions in combination with non-clogging dispensing packages.

It is an object of the present invention to provide liquid detergent compositions containing a surfactant and an abrasive, the detergent composition being highly effective in removing food soils from kitchenware when used undiluted or in the form of a relatively concentrated water slurry, but which is highly acceptable for hand dishwashing in the dilute water solutions typically used with liquid dish- -washing products.
Summary of the Invention The present invention comprises a liquid detergent composition containing by weight:
a) from about 15% to about 50% of an anionic sur-factant;
b) from about 2~ to about 15% of a suds stabilizing nonionic surfactant selected from the group con-sisting of amine oxides, amides, and the ethylene oxide condensates of alcohols and alkyl phenols;
c) from about 1~ to about 20% of a water-insoluble abrasive having a particle diameter of from about 5 to about 250 microns and a hardness on the Mohs scale o.E from about 2 to about 8; and d) from about 20~ to about 82~ water said composition providing an initial suds cover to a dishwashing solution and a suds cover after the washing of eight plates when used at a concentrati.on of 0.07%
in two gallons of 115F water containing 7 grains/
gallons water hardness measured as CaCO3, each plate carrying 4.0 ml. of triglyceride-containing soil.
The relatively low level of abrasive and high sudsing relative to typical liquid scouring cleanser compositions are important to consumer acceptance and safety to dishes. The level and type of surfactants and the resultant sudsing characteristics appear to provide a protective effect that minimizes damage due to abrasion.
Detailed Description of the Invention The detergent compositions of the present invention contain four essent.ia]. components:

a) an anionic surfactant b) a suds stabilizing nonionic surfactant c) a water-insoluble abrasive d) water.
Optional ingredients can be added to provide various per-formance and aesthetic characteristics.
Anionic Surfactant The compositions of this invention contain from about 15% to about 50% of an anionic surfactant or mixtures thereof. Preferred compositions for use as a complete dishwashing product contain from about 20% to about 35~ of anionic surfactant by weight of the composition.
Most anionic detergents can be broadly described as the water-soluble salts, particularly the alkali metal, alkaline earth metal, ammonium and amine salts, of organic sulfuric reaction products having in their molecular structure an alkyl radical containing from about ~ to about 22 carbon atoms and a radical selected from the group consisting of sulfonic acid and sulfuric acid ester radicals. Includecl in the term alkyl is the alkyl portion of high acyl radicals.
Examples of the anionic synthetic detergents which can form the surfactant component of the compositions of the present invention are the sodium, ammonium or potassium alkyl sul-fates, especially those obtained by sulfating the higher alcohols (C8-C18 carbon atoms) sodium or potassium alkyl benzene or alkyl toluene sulfonates, in which the alkyl group contains from about 9 to about 15 carbon atoms, the alkyl radical being either a straight or branched aliphatic chain; sodium or potassium paraffin sulfonates and olefin sulfonates in which the alkyl or alkenyl group contains from abou-t 10 to about 20 carbon atoms; sodium alkyl glyceryl ether sulfonates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid monoglyceride sulfates and sulfonates; sodium or potassium salts of alkyl phenol ethylene oxide ether sulfates with about 1 to about 30 units of ethylene o~ide per molecule and in which the alkyl radicals contain fro~ 8 to about 12 carbon atoms; the reaction products of fatty ~ ~0134 acids esterified with isethionic acid and neutralized with sodium hydroxide where, for example, the fatty acids are derived from coconut oil, sodium or potassium salts of fatty acid amides of a methyl tauride in which the fatty acids, for example, are derived from coconut oil and sodium or potassium beta-acetoxy- or beta-acetamido-alkanesulfonates where the al~ane has from 8 to 22 carbon atoms.
Specific examples of alkyl sulfate salts which can be -employed in the instant detergent compositions include sodium lauryl alkyl sulfate, sodium stearyl alkyl sulfate, sodium palmityl alkyl sulfate, sodium decyl sulfate, sodium myristyl alkyl sulfate, potassium lauryl alkyl sulfate, potassium stearyl alkyl sulfate, potassium decyl sulfate, potassium palmityl alkyl sulfate, potassium myristyl alkyl sulfate, sodium dodecyl sulfate, potassium dodecyl sulfate, potassium tallow alkyl sulfate, sodium tallow alkyl sulfate, sodium coconut alkyl sulfate, potassium coconut al~:yl sulfate~magnesium Cl2_l5 alkyl sulfate and mixtures of these surfactants. Preferred alkyl sulfates include sodium coconut alkyl sulfate, potassium coconut alkyl sulfate, potassium lauryl alkyl sulfate and sodium lauryl alkyl sulfate.
Suitable alkylbenzene or alkyltoluene sulfon~tes include the alkali metal (lithium, sodium, potassium), alkaline earth (calcium, magnesium) and alkanolamine salts of straight-or branched-chain alkylbenzene or alkyltoluene sulfonic acids. Alkylbenzene s~lfonic acids useful as precursors for these surfactants include decyl benzene sulfonic acid, undecyl benzene sulfonic acid, dodecyl benzene sulfonic acid, tridecyl benzene sulfonic acid, tetrapropylene benzene sulfonic acid. Preferred sulfonic acids as precursors of the alkyl-benzene sulfonates useful for compositions herein are those in which the alkyl chain is linear and averages about 12 carbon atoms in length.
E~amples of commercially available alkyl benzene sulfonic acids useful in the present invention include Conoc ~ SA 515 and SA 597 marketed by the Continental Oil Company and Calsoft~ AS 99 marketed by the Pilot Chemical Company.

13~

Particularly preferred anionic surfactants useful herein are alkyl e-ther sulfates having the formula RO(C2H4O)XSO3M wherein R is alkyl or alkenyl of about 10 to about 20 carbon atoms, x is 1 to 30, and M is a water-soluble cation. The alkyl ether sulfates useful in thepresent invention are condensation products of ethylene oxid~ and monohydric alcohols having from abou- 10 IC ~-out 20 carbon atoms. Preferably, R has 10 to 16 carcon ato~nls.
The alcohols can be derived from natural fats, c .g. ~ ccconut oil or tallow, or can be synthetic. Such alcohols are reacted with 1 to 30, and especially 1 to 12, molar pro-portions of ethylene oxide and the resulting mixture of molecular species is sulfated and neutralized.
Specific examples of alkyl ether sulfa-tes of the present invention are sodium coconut alkyl triethylene glycol ether sulfate, magnesium tallow alkyl triethylene glycol ether sulfate, and sodium taliow alkyl hexaoxy ethylene sulfate. Preferred alkyl ether sulfates are those comprising a mixture of individual compounds, said mixture having an average alkyl chain length of from about 12 to 16 carbon atoms and an average degree of ethoxylation of from about 1 to 12 moles of ethylene oxide.
Additional examples of anionic surfactants useful herein are the compounds which contain two anionic func-tional groups. These are referred to as di-anionic sur-factants. Suitable dianionic surfactants are the disul-fonates, disulfates, or mixtures thereof which may be represented by the following formula:
3)2M2,R(sO4)2M2~R(so3)(so4~M2 where R is an acyclic aliphatic hydrocarbyl group having 15 to 20 carbon atoms and M is a water-solubilizing cation, for example, the C15 to C20 disodium 1,2-alkyldisulfates, C15 to C20 dipotassium-1,2-alkyldisulfonates or disulfates, di-sodium l,9-hexadecyl disulfates, C15 to C20 disodium 1,2-alkyldisulfonates, disodium l,9-stearyldisulfa-tes and 6,10-octadecyldisulfates.

~6~3134 Nonionlc Surfactant The compositions of this invention contain from abou-t

2% to about 15~, preferably from about 3% to about 3% of a suds stabilizing nonionic surfactant or mixtures thereof.
The presence of this component is essential to satisfactory performance and acceptance as a complete dishwashing product.
In preferred embodiments the nonionic surfactants will be in a weight ratio to the anionic surfactants of from about 1:10 to about 1:2, most preferably from about 1:7 to about 1:3.
Nonionic surfactants operable in the instant composi-tions are of three basic types -~ the ethylene oxide condensates, the amides, and the amine oxide semi-polar nonionics.
The ethylene oxide condensates are broadly c'e~ined as compounds produced by the condensation of ethylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound, whi.ch can be aliphatic or alkyl aromatic in -nat~lre. The length of the hydrophilic or polyo.xyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements.
Examples of such ethylene oxide condensates include:
(1) The condensation products of aliphatic alcohols with ethylene oxide. The alkyl chain of the aliphatic alcohol can either be straight o.r brancl1ed and genexally contains from about 10 to about 14 carbon atoms for best performance as suds stabilizers. Examples of such ethoxylated alcohols include the condensation product of about 6 moles of ethylene oxide with 1 mole of tridecanol, myristyl alcohol condensed with about 10 moles of ethylene oxide per mole of myristyl alcohol, the condensation product of ethylene oxide with coconut fatty alcohol wherein the coconut alcohol is a mixture of fatty alcohols with alkyl chains varying from 10 to 14 carbon atoms and wherein the condensate contains about 6 moles of ethylene oxide per mole of alcohol, and the condensation product of about 9 moles of ethylene oxide wi-th the above-d2scribed coconut alcohol. An example of a commerci.ally av;l.il.able nonionic surfactant of ~ ~i0134 _ ~ 7 -thls type includes Neodol 23-6.5 marketed ~y the Shell Chemical Company.
(2) The ethylene oxide condensates of alkyl phenols.
These compounds include the condensation products of alkyl phenols having an alkyl group containing from a~out 6 to 12 carbon atoms in either a straight chain or branched chain configuration~ with ethylene oxide, the ethylene oxide being present in amounts equal to 5 to 25 moles of ethylene oxide per mole of alkyl phenol. The alkyl substituent in such compounds can be derived, for example, from polymerized propylene, diisobutylene, octene, or nonene. Examples of compounds of this type include nonyl phenol condensed with about 9.5 moles of ethylene oxide per mole of nonyl phenol, dodecyl phenol condensed with about 12 moles of ethylene oxide per mole of p~enol, dinonyl phenol condensed with about 15 moles of ethylene oxide per mole of phenol, di-isooctylphenol condensed with about 15 moles of ethylene oxide per mole of phenol. Commerciallyfi~available nonionic surfactants of this type include Igepal'~CO-610 marketed by the GAF Corporation; and Trito~ X-45, X-114, X-100 and X-102, all marketed by the Rohm and Haas Company.
Examples of the amide type of nonionic surface active agent include the ammonia, monoethanol and diethanol amides of fatty acids having an acyl moi.ety of from about 8 to about 18 carbon atoms. These acyl moieties may be derived from naturally occurring glycerides, e.g., coconut oil, palm oil, soybean oil and tallow, but can be derived synthetic-ally, e.g., by the oxidation of petroleum, or by hydro-genation of carbon monoxide by the Fischer-Tropsch process.
The monoethanol amides and diethanolamides of C12 14 fatty acids are preferred.
Amine oxide semi-polar nonionic surface active agents comprise compounds and mixtures of compounds having the formula: R2 1( 2 4)n~

wherein Rl is an alkyl, 2-hydroxyalkyl, 3-hydroxyalkyl, or

3-alkoxy-2~hydroxypropyl radical in which the alkyl and alkoxy, respectlvely, contain from about 8 to about 18 carbon atoms, R2 and R3 are me-thyl, ethyl, propyl, iso-propyl, 2-hydroxye-thyl, 2-hydroxypropyl, or 3-hydroxy-propyl and n is from 0 to about 10. Particularly preferred are amine oxides of the formula:
ll2 Rl - N--~O

wherein Rl is a C10_14 alkyl and R2 and R3 are methyl or ethyl.
The le~el and type of surfactants used in the composi-tions oE this invention provide an initial suds cover to a dishwashing solution and a suds cover after the washing of 8 plates when used at a concentration of 0.07~ in 2 gallons of 115F. water containing 7 grains/ gallon water hardness measured as CaCO3, each plate carrying ~.0 ml of a trigly-ceride containing soil. Suds are generated by agitation and the suds cover and height measured. A dinner plate carrying the soil is washed successively with the introduction of 4.0 ml of soil each time. An essentially complete suds cover of the washillg solution is more impor-tant than suds height, but, preferably, the suds cover after the washing of ~ plates is at least about 1/2 inch in height.
The sudsing characteristic of the compositions of the invention is that necessary to provide the user of the product with an indication of cleaning potential in a dishwashing solution. Soils encountered in dishwashing act as suds depressants and the presence or absence of suds from the surface of a dishwashing solution is a convenient guide to product usage. Mixtures of anionic surfactants and nonionic surfactants, especially amides and amine oxide nonionic surfactants, are utilized in the compositions of the invention because of their high sudsing characteristics, their suds stability in the presence of food soils and their ability to indicate accurately an adequate level of product us~ in tile presence of soil.

~()134 g Optional Surfactants _ _ The compositions of the invention may contain optional surfactants other than anionic and nonionic surfactants such as ampholytic, zwitterionic and catlonic surfactants.
Ampholytic surfactants can be broadly described as derivatives of aliphatic amines which contain a long chain of about 8 to 18 carbon atoms and an anionic water-solu-bilizing group, e.g. carboxy, sulfo or sulfate. Examples of compounds falling within this definition are sodium-3-dodecylamino propane sulfonate, and dodecyl dimethylammonium hexanoate.
Zwitterionic surface active agents operable in the instant composition are broadly described as internally-neutralized derivatives of aliphatic quaternary ammonium and phosphonium and tertiary sulfonium compounds in which the aliphatic radical can be straight chain or branched, and wherein one of the aliphatic substituents contains from about 8 to 18 carbon atoms and one contains an anionic water solubilizing group, e.g., carboxy, sulfo, sulfato, phos-phato, or phosphono.
Cationic surfactants such as quaternary ammonium compounds can find optional use in the practice of the invention to the extent they are compatible with the other surfactants in the particular composition.
Abraslve The abrasive agent can be any of the water-insoluble abrasive materials known in the art which have a particle diameter of from about 5 to about 250, preferably from about 20 to about 125, microns and a hardness on the Mohs scale of from about 2 to about 8, preferable from about

4 to about 7. Included are materials such as agate, mica, calcite, garnet, quartz, kieselguhr, silica, marble, tripoli, flint, feldspar, emeryl pumice, alumina, perlite, expanded perlite, volcanic ash, diatomaceous earth, bentonite, amorphous silica from dehydrated silica gels, precipitated silica, plastics such as polystyrene and polyacrylates, and natural and synthetic aluminosilicates and mixtures thereof.

; ~ ~

a~34 The amount of abrasive included in the compositions is in the range of from about 1% to about 20% of the total composition be weight. Preferred compositions contain from about 3% to about 12~ by weight of abrasive.
Water The compositions of this invention contain from about 20% to about 82~, preferably from about 40% to about 75%, water.
Optional Ingredients .
The compositions of this invention can contain up to about 20%, preferably from about 5% to abaut 15%, by weight of detergency builders either of the organic or inorganic types. Examples of water-soluble inorganic builders which can be used, alone or in admixture with themselves and organic alkaline sequestrant builder salts, are alkali metal carbonates, polyphosphates, and silicates. Specific ex-amples of such salts are sodium tripolyphosphate, sodium carbonate, potassium carbonate, sodium pyrophosphate, potassium pyrophosphate, potassium tripolyphosphate, and sodium hexametaphosphate. Examples of organic builder!salts which can be used alone, or in admixture with each other or with the preceding inorganic alkaline builder salts, are alkali metal polycarboxylates, e.g., water-soluble citrates such as sodium and potassium citrate, sodium and potassium tartrate, sodium and potassium ethylenediaminetetraacetate, sodium and potassium N-(2-hydroxyethyl)-ethylene diamine triacetates, sodium and potassium nitrilo triacetates ~NTA) and sodium and potassium N-t2-hydroxyethyl)-nitrilo diace-tates. Other organic builder salts include the alkali metal salts of phytic acid, e.g., sodium phytate (see U.S. Patent 2,739,942). Water-soluble salts of ethane-l-hydroxy-l,l-diphosphonate (EHDP) are also suitable. Mixtures of any of the preceding water-soluble organic or inorganic builder salts can be used.

, j The compositions of this invention can contain insolu-ble builder salts selected from certain zeolites or aluminosilicates. One such aluminosilicate which is useful in the compositions of the invention is water-insoluble crystalline aluminosilicate ion exchange material of the formula:

Naz[(Alo2)z.(sio2)y].xH2o wherein z and y are at least 6, the molar ratio of z to y is from 1.0 to 0.5 and x is from 10 to 264, said material having a particle size diameter of from about 0.1 micron to about 10 microns, a calcium ion exchange capacity of at least about 200 mg. CaCo3eq./gram and a calcium ion exchange rate of at least about 2 grains Ca++/gallon/
minute/gram. ThiS ion exchange builder is more fully described in Belgian Patent 814,874 issued on November 12, 1974 to Corkill et al. A preferred aluminosilicate of this type is Zeolite A.
A second water-insoluble aluminosilicate ion exchange material useful herein is water-insoluble amorphous hydrated aluminosilicate material of the emperical formula:

MZ(ZA102-Ysio2) wherein M is sodium, potassium, ammonium, or substituted ammonium, z is from about 0.5 to about 2, y is 1 and said material having a particle size diameter of less than 100, preferably less than 10, microns, a magnesium ion exchange capacity of at least about 50 milligrams equivalent of CaCO3 hardness per gram of anhydrous aluminosilicate and a Mg++ exchange rate of at least about 1 grain/
gallon/minute/gram/gallon; and mixtures thereof. This ion exchange builder is more fully described in Gedge et al's French Patent 2,237,839 published February 14, 1975.

1~60134 Alcohols, such as ethyl alcohols, and hydrotropes, such as sodium and potassium toluene sulfonate, sodium and potassium xylene sulfonate, trisodium sulfosuccinate and related compounds (as disclosed in U.S. Patent 3,915,903 and urea, can be utilized in the interests of achieving a desired product phase stability, viscosity, and yield value. Ethyl alcohol at a level of from about 8~ to about 12% and potassium or sodium sulfosuccinate at a level of from about 2~ to about 5% are particularly useful in the compositions of the invention.
Also particularly useful in the compositions of this invention are suspending or thickening agents such as those disclosed in U.S. Patent 3,393,153, including col-loidal silica having a mean particle diameter ranging from 15 about 0.01 micron to about 0.05 micron, colloidal clays such as bentonites or chemically treated bentonites, iso-morphous silicates, especially those with a high magnesium content, particulate polymers such as polystyrene, oxidized polystyrene having an acid number of from 20 to about 40, sulfonated polystyrene having an acid number of from about 10 to about 30, polyethylene, oxidized polyethylene having an acid number of from about 10 to about 30; sulfonated polyethylene having an acid number of from about 5 to about 25; polypropylene, oxidized polypropylene having an acid number of from about 10 to about 30 and sulfonated poly-propylene having an acid number of from about 5 to about 25, all of said particulate polymers having mean particle diameters ranging from about 0.01 micron to about 30 microns. Other examples of suspending and thickening agents include copolymers of styrene with monomers such as maleic anhydride, nitrolonitrile, methacrylic acid and lower alkyl esters of methacrylic acid, copolymers of styrene with methyl or ethyl acrylate, methyl or ethyl maleate, vinyl acetate, acrylic, maleic or fumaric acids and mixturtes thereof. The mole ratio of ester and/or acid to styrene is preferably in the range from about 4 to about 40 styrene units per ester and/or acid unit. Such materials preferably have a mean particle diameter range of from about 0.05 micron to about 1 micron and molecular weights ranging from about 500,000 ~o about 2,000,000. Cellulosic polymers such as carboxymethyl cellulose and hydroxypropyl cellulose and gums such as guar gum and gum tragacanth are also suitable suspending and thickening agents.
Colloidal clays are especially preferred suspending and thickening agents and provide particularly stable composi-tions when product pH is maintained or adjusted to a rangeof from about 8.0 to about 10.0, preferably from about 8.0 to about 9Ø An alkaline pH value has an additional benefit as an aid to cleaning, particularly when the product is used undiluted for scouring purposes.
The detergent compositions of this invention can contain, if desired, any of the usual ad~uvants, diluents and additives, for example, perfumes, enzymes, dyes, anti-tarnishing agents, antimicrobial agents, and the like, without detracting from the advantageous properties of the compositions. Alkalinity sources and pH buffering agents such as alkali metal carbonates and bicarbonates, mono-ethanolamine, triethanolamine and alkali metal hydroxides can also be utilized.
The presence of at least about 0.5% by weight potassium ions can be beneficial to the physical characteristics of the compositions.
PhYsical Characteristics of the Detergent Composition The liquid detergent compositions of the invention contain abrasives as suspended solids and may contain other solid or liquid ingredients that provide desired product stability characteristics and that affect product viscosity.
In general, the preferred products of the invention are thixo-tropic or pseudoplastic and resistant to settling out of the abrasive ~r, or other solids yet sufficiently fluid for dispensing. In general, the compositio~s have a Brookfield viscosity of from about 400 cps to about 2500 cps when measured at 50 rpm and a yield value of from about 5 to about 600 dynes per square centimeter at 25C.
The important physical property consideration of the pre-ferred compositions of the invention is their yield value. The consistency of simple or Newtonian liquids is a function of the nature of the material, temperature, and pressure only.
This consistency is known as the "fluid viscosity coeffi-cient," "absolute viscosity," or merely "viscosity," and is usually measured in centipoises (1 centipoise = 0.01 gram/
centimeter-second). With a Newtonian liquid, any force applied to the s~stem produces some deformation, according to the formula du/dr=F/~ where dutdr = the rate of shear; F =
the shear stress, or shearing force per unit area; and ~=
the viscosity coefficieilt.
In the case of non-Newtonian li~uids, on the other hand, the consistency is a function of the material, pres-sure, temperature, and also the shear stress applied to thesystem. Those non-Newtonian liquids which are classified as Bingham plastics, or real plastics, are not always deformed when a force is applied to the system. Deformation, if any, ta~es place according to the formula du/dr=(F~ where ~ =
the apparent viscosity, or plastic viscosity, at the shear stress F;r=a chaxacteristic of the liquid called the yield stress, or yield value, measured in units of pressure;
and du/dr and F are as defined above.
If the shear stress applied to the system is less than the yield value, the system will not be deformed at all.
Hence a Bingham plastic system is capable of supporting indefinitely insoluble particulate material which has a density greater than that of the supporting medium, so long as the material has such a particle size and density that the shear stress which each particle places on the supporting medium does not exceed the yield value.

~6~3~34 This is to be contrasted with suspension of heavy insoluble particulate material in Newtnnian liquids with high viscosities. In highly viscous Newtonian liquids, insoluble particulate material is suspended only because the rate of flow is slow. In Bingham plastics, insoluble par-ticulate material is suspended because the stress imposed by the particles does not exceed the yield value of the li~uid, and therefore, there is no flow at all. Of course, if the yield value of the supporting medium should sufficiently decrease for any reason, the particles would no longer be suspended. This could be caused, for example, by a physical or chemical change in the supporting medium. If one of the components of the supporting medium is an emulsion which settles into layers upon standing, the yield value can be lost temporarily, but in such a case, the original compo-sition can be reconstituted by mixin~J. If a chemicalreaction either consumes a vital component or produces a damaging one, the loss of yield value can be permanent.
Because it is usually not known whether a system behaves in a truly plastic manner at low shear rates, the measurement of exact yield values is estimated, in dynes per square centimeter, by the following relationship:
Yield Value =
~iscosit~ at 0.5 r.p.m. - Viscosity at 1 r p.m.

This relationship represents an extrapolation of the sheer curve to 0 r.p.m. since an absolute shear stress canr.ot be measured at 0 r.p.m.
The yield value of the liquid detergent compositions of this invention ranges from about 5 to about 600 dynes per square centimeter. If the yield value is too low, the insoluble, particulate material will not be suspended, because the weight of -the individual particles, distributed over the area which supports the particles, will e~ceed the yield value. However, if the yield value is too great, the composition will become thick and unmanageable because as the yield value increases, so will the apparent viscosity.

A preferred range of yield values to support the insoluble particulate material used in the liquid detergent compositions of this invention is from about 100 to about 400 dynes per square centimeter, most preferably from about 200 to about 300 dynes per square centimeter.
As an alternative, compositions containing abrasives having a density approximating that of the detergent compo-sition can be relatively stable without haviny the preferred yield values.
The following examples are given to illustrate the detergent compositions of the invention. All amounts and percentages are by weight unless otherwise indicated.
EXAMPLES
Liquid detergent compositions of the invention were prepared containing the ingredients listed below:
A B C D E
Sodlum C12 13 alkyl sulfate 11.5~11.5~ 11.5~ 11.5~ 11.5 Sodium C12_13 alkyl 12.512.5 12.5 12.2 12.5 ethoxy ~3) sulfate C12 14 alkyl dimethyl-4.0 4.0 4.0 4.0 amine oxide C12_14 alkyl monoethanol- _ _ _ 6.0 amide Trisodium sulfosuccinate 2.0 2.0 2.0 3.0 3.0 Calcite ~avg. - 10,0 diameter = 125 microns -Moh's Hardness = 3) Diatomaceous earth lavg. 5.0 - - 5.0 5.0 diameter = 40 microns -Moh's Hardness 5 5-7) Silica ~43-105 micron - - 5.0 diameter - Moh's Hardness = 7) Bentonite clay Isuspending 2.5 2.5 - 2.2 2.2 agent) Fumed silica (suspending - - 2.0 agent) Ethanol 10.0 10.010.0 10.0 10.0 Water and miscellaneous Balance Viscoslty ~Brookfield- 1200-1200- 1200- 1200- 1200-50 rpm)1800cps1800cps 1800cps1800cps 1800cps Yield Value (dynes/cm2) 250250 250 250 250 ~, 0~34 All compositions listed above contain approximately 45 to 55~ water and have a pH value in the range of 8.0 to 10Ø
The compositions are entirely satisfactory wher, used in dilute solutions as a dishwashing detergent compositions and are substantially superior to typical li~uid dishwashing - deterg-nt compositions when used undiluted or in concentrated solution for removal of tightly attached soils.
Equivalent results are obtained when C12 alkyldiethanol-amide and the reaction product of a C12 15 alcohol and 8 moles of ethylene oxide are substituted for the C12 alkyl- -monoethanol-amide of Composition E.
Equivalent results are obtained when sodium C12 13 alkylbenzene sulfona-te and C12 15 paraffin sulfonate are substituted for the sodium C12 13 alkyl sulfate of composi-tions A, B, C, D and E.
WHAT IS CLAIMED IS:

Claims (11)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A liquid detergent composition comprising by weight:
(a) from about 15% to about 50% of an anionic surfac-tant (b) from about 2% to about 15% of a suds stabilizing nonionic surfactant selected from the group con-sisting of amine oxides, amides and the ethylene oxide condensates of alcohols and alkyl phenols;
(c) from about 1% to about 20% of a water-insoluble abrasive having a particle diameter of from about 5 to 250 microns and a hardness on the Mohs scale of from about 2 to about 8; and (d) from about 20% to about 82% water;
said composition providing an initial suds cover to a dish-washing solution and a suds cover after the washing of eight plates when used at a concentration of 0.07% in two gallons of 115°F. water containing 7 grains/gallon water hardness measured as CaCO3, each plate carrying 4.0 ml.
of triglyceride-containing soil.

2. The composition of Claim 1 wherein the anionic surfac-tant comprises a material selected from the group consist-ing of alkyl sulfates, alkyl ether sulfates, alkylbenzene sulfonates, paraffin sulfonates, olefin sulfonates and mixtures thereof.

3. The composition of Claim 2 wherein the suds stabiliz-ing nonionic surfactant comprises a material selected from the group consisting of ethanolamides, amine oxides and mixtures thereof.

4. The composition of Claim 3 wherein the abrasive comprises a material selected from the group consisting of quartz, silica, diatomaceous earth, feldspar, high density perlite, calcite and mixtures thereof.

5. The composition of Claim 1, 2 or 3 wherein the pH
value of a 10% solution in water is from about 8.0 to about 10Ø

6. The composition of Claim 4 wherein the pH value of a 10% solution in water is from about 9.0 to about 10Ø

7. The composition of Claim 6 which comprises a suspending and thickening agent selected from the group consisting of colloidal clays, colloidal silica, isomorphous silicates, and mixtures thereof.

8. The composition of Claim 7 wherein the suspending and thickening agent is a colloidal clay.

9. The composition of Claim 8 which comprises ethanol and an alkali metal sulfosuccinate.

10. The composition of Claim 1, 3 or 7, which comprises a suspending and thickening agent and which has a yield value of from about 100 dynes per square centimeter to about 400 dynes per square centimeter.

11. The composition of Claim 9 which has a yield value of from about 200 dynes per square centimeter to about 300 dynes per square centimeter.