Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/395—Bleaching agents
  • C11D3/3956—Liquid compositions

Definitions

• This invention relates to liquid cleaning compositions incorporating a chlorine bleach ingredient, cross-linked polycarboxylate polymers, a rheology stabilizing agent, and a buffering agent, and which display enhanced physical stability in the presence of bleach.
• a liquid automatic dishwashing detergent composition additionally containing builder and optional surfactant and metalate, and exhibiting shear thinning behavior, i.e., high viscosity at low rates of shear and lower viscosities at high rates of shear.
• Thickened aqueous cleaning compositions are known, having been taught in U.S. Pat. Nos. 3,843,548; 3,558,496; 3,684,722; 4,005,027; and 4,116,851.
• benzoic acid or salt or derivative thereof in cleaning compositions is known, as taught in U.S. Pat. Nos. 4,810,409; 4,810,413; 4,576,728; 3,932,316; and 4,333,862.
• compositions containing a cross-linked polycarboxylate polymer, a chlorine bleach ingredient, a rheology stabilizer, and a buffering agent discloses applicant's compositions containing a cross-linked polycarboxylate polymer, a chlorine bleach ingredient, a rheology stabilizer, and a buffering agent.
• compositions of this invention are liquid cleaning compositions comprising, by weight:
• compositions of the present invention comprise four essential ingredients: a chlorine bleach ingredient, a cross-linked polycarboxylate polymer thickening agent, a rheology stabilizing agent, and an alkalinity buffering agent.
• compositions include a bleach ingredient which yields a hypochlorite species in aqueous solution.
• the hypochlorite ion is chemically represented by the formula OCl ⁇ .
• the hypochlorite ion is a strong oxidizing agent, and materials which yield this species are considered to be powerful bleaching agents.
• hypochlorite ion The strength of an aqueous solution containing hypochlorite ion is measured in terms of available chlorine. This is the ox­idizing power of the solution measured by the ability of the solution to liberate iodine from an acidified iodide solution.
• One hypochlorite ion has the oxidizing power of 2 atoms of chlorine, i.e., one molecule of chlorine gas.
• hypochlorite-yielding compounds contain active chlorine, partially in the form of hypochlorous acid moieties and partially in the form of hypochlorite ions.
• active chlorine is reported to be in the form of hypochlorite ion.
• bleaching agents which yield a hypochlorite species in aqueous solution include alkali metal and alkaline earth metal hypochlorites, hypochlorite addition products, chloramines, chlorimines, chloramides, and chlorimides.
• Specific examples of compounds of this type include sodium hypochlorite, potassium hypochlorite, monobasic calcium hypochlorite, dibasic magnesium hypochlorite, chlorinated trisodium phosphate dodecahydrate, potassium dichloroisocyanurate, sodium dichloroisocyanurate, sodium dichloroisocyanurate dihydrate, trichlorocyanuric acid, 1,3-dichloro-5,5-dimethylhydantoin, N-chlorosulfamide, Chloramine T, Dichloramine T, chloramine B and Dichloramine B.
• a preferred bleaching agent for use in the compositions of the instant invention is sodium hypochlorite, potassium hypochlorite, or a mixture thereof.
• hypochlorite-yielding bleaching agents are available in solid or concentrated form and are dissolved in water during preparation of the compositions of the instant invention. Some of the above materials are available as aqueous solutions.
• Bleaching agents are dissolved in the aqueous liquid component of the present composition.
• Bleaching agents can provide from about 0.2% to about 2.5% available chlorine by weight, preferably from about 0.5% to about 1.5% available chlorine, by weight of the total composition.
• the thickening agent in the compositions of the present invention is a cross-linked polycarboxylate polymer thickening agent.
• This polymer preferably has a molecular weight of from about 500,000 to about 5,000,000, more preferably from about 750,000 to about 4,000,000.
• the polycarboxylate polymer is preferably a carboxyvinyl polymer.
• carboxyvinyl polymer Such compounds are disclosed in U.S. Patent 2,798,053, issued on July 2, 1957, to Brown, the specification of which is hereby incorporated by reference. Methods for making carboxyvinyl polymers are also disclosed in Brown.
• a carboxyvinyl polymer is an interpolymer of a monomeric mixture comprising a monomeric olefinically unsaturated carboxylic acid, and from about 0.1% to about 10% by weight of the total monomers of a polyether of a polyhydric alcohol, which polyhydric alcohol contains at least four carbon atoms to which are attached at least three hydroxyl groups, the polyether containing more than one alkenyl group per molecule.
• Other monoolefinic monomeric materials may be present in the monomeric mixture if desired, even in predominant proportion.
• Carboxyvinyl polymers are substan­tially insoluble in liquid, volatile organic hydrocarbons and are dimensionally stable on exposure to air.
• Preferred polyhydric alcohols used to produce carboxyvinyl polymers include polyols selected from the class consisting of oligosaccarides, reduced derivatives thereof in which the carbonyl group is converted to an alcohol group, and pentaerythritol; most preferred is sucrose or pentaerythritol. It is preferred that the hydroxyl groups of the modified polyol be etherified with allyl groups, the polyol having at least two allyl ether groups per polyol molecule. When the polyol is sucrose, it is preferred that the sucrose have at least about five allyl ether groups per sucrose molecule. It is preferred that the polyether of the polyol comprise from about 0.1% to about 4% of the total monomers, more preferably from about 0.2% to about 2.5%.
• Carbopol® Various carboxyvinyl polymers are commercially available from B. F. Goodrich Company, New York, N.Y., under the trade name Carbopol®. These polymers are also known as carbomers or polyacrylic acids.
• Carboxyvinyl polymers useful in formulations of the present invention include Carbopol 910 having a molecular weight of about 750,000, Carbopol 941 having a molecular weight of about 1,250,000, and Carbopols 934 and 940 having molecular weights of about 3,000,000 and 4,000,000, respectively.
• Preferred polycarboxylate polymers of the present invention are non-linear, water-dispersible, polyacrylic acid cross-linked with a polyalkenyl polyether and having a molecular weight of from about 750,000 to about 4,000,000.
• polycarboxylate polymers for use in the present invention are Sokalan PHC-25®, a polyacrylic acid available from BASF Corporation, Polygel DK available from 3-V Chemical Corporation, and the Carbopol 600 series resins available from B. F. Goodrich, especially Carbopol 614, 616 and 617. It is believed that these are more highly cross-linked than the 900 Carbopol series polymers and have molecular weights between about 1,000,000 and 4,000,000. Mixtures of polycarboxylate polymers as herein described may also be used in the present invention.
• the polycarboxylate polymer thickening agent is preferably utilized with essentially no clay thickening agents since the presence of clay usually results in a less desirable product having phase instability.
• the polycarboxylate polymer is preferably used instead of clay as a thickening agent in the present compositions.
• the polycarboxylate polymer thickening agent in the compositions of the present invention is present at a level of from about 0.1% to about 10%, preferably from about 0.25% to about 5%, most preferably from about 0.5% to about 2%.
• the polycarboxylate polymer thickening agent provides an apparent viscosity at high shear of greater than about 500 centipoise and an apparent yield value of from about 40 to about 800, and most preferably from about 60 to about 600, dynes/cm2 to the composition.
• the yield value is an indication of the shear stress at which the gel strength is exceeded and flow is initiated. It is measured herein with a Brookfield RVT model viscometer with a T-bar B spindle at about 77 o F (25 o C) utilizing a Helipath drive during associated readings. The system is set to 0.5 rpm and a torque reading is taken for the composition to be tested after 30 seconds or after the system is stable. The system is stopped and the rpm is reset to 1.0 rpm. A torque reading is taken for the same composition after 30 seconds or after the system is stable.
• the rheology stabilizing agents useful in the present invention have the formula: wherein each X, Y, and Z is -H, -COO-M+, -Cl, -Br, -SO3-M+, -NO2, -OCH3, or a C1 to C4 alkyl and M is H or an alkali metal.
• this component include pyromellitic acid, i.e., where X, Y, and Z are -COO-H+; hemimellitic acid and trimellitic acid, i.e., where X and Y are -COO-H+ and Z is -H.
• Preferred rheology stabilizing agents of the present invention are sulfophthalic acid, i.e., where X is -SO3-H+, Y is -COO-H+, and Z is -H; other mono-substituted phthalic acids and di-substituted benzoic acids; and alkyl-, chloro-, bromo-, sulfo-, nitro-, and carboxy- benzoic acids, i.e., where Y and Z are -H and X is a C2 to C4 alkyl, -Cl, -Br, -SO3-H+, -NO2, and -OCH3, respectively.
• rheology stabilizing agents useful in the present invention are benzoic acid, i.e., where X, Y, and Z are -H; phthalic acid, i.e., where X is -COO-H+, and Y and Z are -H; and toluic acid, where X is -CH3 and Y and Z are -H; and mixtures thereof.
• All the rheology stabilizing agents described above are the acidic form of the species, i.e., M is H. It is intended that the present invention also cover the salt derivatives of these species, i.e., M is an alkali metal, preferably sodium or potassium. In fact, since the pH of compositions of the present invention are in the alkaline range, the rheology stabilizing agents exist primarily as the ionized salt in the aqueous composition herein. It is also intended the anhydrous derivatives of certain species described above be included in this invention, e.g., pyromellitic dianhydride, phthalic anhydride, sulfophthalic anhydride, etc.
• Mixtures of the rheology stabilizing agents as described herein may also be used in the present invention.
• This component is present in an amount of from about 0.05% to about 2%, preferably from about 0.1% to about 1.5%, most preferably from about 0.2% to about 1%, by weight, of the composition.
• Cross-linked polymers especially those of high molecular weight, as used in the present bleach-containing composition, are vulnerable to bleach-initiated degradation and result in a loss of rheology that can be unacceptable for some applications.
• a certain small percentage of the chlorine bleach ingredient is present in solution in the form of a free radical, i.e., a molecular fragment having one or more unpaired electrons.
• These radicals although short lived, are highly reactive and may initiate the degradation of certain other species in solution, including the cross-linked polycarboxylate polymers, via propagation mechanism.
• the polymers of this invention are susceptible to this degradation because of the presumed oxidizable sites present in the cross-linking structure.
• rheology stabilizing agent substantially increases the physical stability, i.e., rheological stability, of the composition of the present invention when added.
• rheology stabilizing agent functions as a free radical scavenger, tying up the highly reactive species in the composition and preventing them from attacking the degradation-susceptible structure of the polycarboxylate polymers.
• rheology stabilizing agent ineffective as the rheology stabilizing agent in the present invention because they react with chlorine bleach or are unable to impede the interaction between the bleach ingredient and the polymeric thickening agent.
• One of the preferred rheology stabilizing agents herein is benzoic acid. Benzoates have been characterized in the art as weak radical scavengers and nearly ineffective in an alkaline medium. However, phthalic and toluic acids, which have not been characterized as radical scavengers, function effectively as a rheology stabilizing agent.
• compositions it is generally desirable to also include one or more buffering agents capable of maintaining the pH of the compositions within the alkaline range, determined as the pH of the undiluted composition ("as is") with a pH meter. It is in this pH range that optimum performance and stability of the bleach are realized, and it is also within this pH range wherein optimum composition chemical and physical stability are achieved.
• composition pH above about 10, preferably above about 11.5, minimizes undesirable chemical decomposition of the active chlorine, hypochlorite-yielding bleaching agents. Maintenance of this particular pH range also minimizes the chemical interaction between the strong hypochlorite bleach and the surfactant compounds present in the instant compositions. Finally, as noted, high pH values such as those maintained by an optional buffering agent serve to enhance the soil and stain removal properties during utilization of the present compositions.
• any compatible material or mixture of materials which has the effect of maintaining the composition pH within the alkaline pH range, and preferably within a 10 to about 13 range, can be utilized as the buffering agent in the instant invention.
• Such materials can include, for example, various water-soluble, inor­ganic salts such as the carbonates, bicarbonates, sesquicar­bonates, silicates, pyrophosphates, phosphates, tetraborates, and mixtures thereof.
• Examples of materials which can be used either alone or in combination as the buffering agent herein include sodium carbonate, sodium bicarbonate, potassium carbonate, sodium sesquicarbonate, sodium silicate, potassium silicate, sodium pyrophosphate, tetrapotassium pyrophosphate, tripotassium phosphate, trisodium phosphate, anhydrous sodium tetraborate, sodium tetraborate pentahydrate, potassium hydroxide, sodium hydroxide, and sodium tetraborate decahydrate. Combination of these buffering agents, which include both the sodium and potassium salts, may be used.
• This may include mixtures of tetrapotassium pyrophosphate and trisodium phosphate in a pyrophosphate/phosphate weight ratio of about 3:1, mixtures of tetrapotassium pyrophosphate and tripotassium phosphate in a pyrophosphate/phosphate weight ratio of about 3:1, and mixtures of anhydrous sodium carbonate and sodium silicate in a carbonate/silicate weight ratio of about 1:3 to about 3:1, preferably from about 1:2 to about 2:1.
• Buffering agents can generally comprise from 1% to about 25% by weight, preferably from about 2.5% to about 20% by weight, of the total composition.
• compositions of this invention can contain from 0% to about 5%, preferably from about 0.1% to about 2.5%, of a bleach-stable detergent surfactant.
• Desirable detergent surfactants include nonionic detergent surfactants, anionic detergent surfactants, amphoteric and zwitterionic detergent surfactants, and mixtures thereof.
• nonionic surfactants examples include:
• Specific examples of such compounds include a condensation product of 1 mole of coconut fatty acid or tallow fatty acid with 10 moles of ethylene oxide; the condensation of 1 mole of oleic acid with 9 moles of ethylene oxide; the condensation product of 1 mole of stearic acid with 25 moles of ethylene oxide; the condensation product of 1 mole of tallow fatty alcohols with about 9 moles of ethylene oxide; the condensation product of 1 mole of oleyl alcohol with 10 moles of ethylene oxide; the condensation product of 1 mole of C19 alcohol and 8 moles of ethylene oxide; and the condensation product of one mole of C18 alcohol and 9 moles of ethylene oxide.
• the condensation product of a fatty alcohol containing from 17 to 19 carbon atoms, with from about 6 to about 15 moles, preferably 7 to 12 moles, most preferably 9 moles, of ethylene oxide provides superior spotting and filming performance. More particularly, it is desirable that the fatty alcohol contain 18 carbon atoms and be condensed with from about 7.5 to about 12, preferably about 9, moles of ethylene oxide.
• condensation products of 1 mole of alkyl phenol wherein the alkyl chain contains from about 8 to about 18 carbon atoms and from about 4 to about 50 moles of ethylene oxide are the condensation products of 1 mole of decylphenol with 40 moles of ethylene oxide; the condensation product of 1 mole of dodecyl phenol with 35 moles of ethylene oxide; the condensation product of 1 mole of tetradecylphenol with 25 moles of ethylene oxide; the condensation product of 1 mole of hectadecylphenol with 30 moles of ethylene oxide, etc.
• Useful surfactants in detergent compositions are those having the formula RO-(C2H4O) x R1 wherein R is an alkyl or alkylene group containing from 17 to 19 carbon atoms, x is a number from about 6 to about 15, preferably from about 7 to about 12, and R1 is selected from the group consisting of: preferably, hydrogen, C1 ⁇ 5 alkyl groups, C2 ⁇ 5 acyl groups and groups having the formula (C y H 2y O) n H wherein y is 3 or 4 and n is a number from one to about 4.
• Particularly suitable surfactants are the low-sudsing com­pounds of (4), the other compounds of (5), and the C17 ⁇ 19 materials of (1) which have a narrow ethoxy distribution.
• surfactants are bleach-stable but some are not.
• the detergent surfactant is bleach-stable.
• Such surfactants desirably do not contain functions such as unsaturation and some aromatic, amide, aldehydic, methyl keto or hydroxyl groups which are susceptible to oxidation by the hypochlorite.
• Bleach-stable anionic surfactants which are especially resistant to hypochlorite oxidation fall into two main groups.
• One such class of bleach-stable anlonic surfactants are the water-soluble alkyl sulfates and/or sulfonates, containing from about 8 to 18 carbon atoms in the alkyl group.
• Alkyl sulfates are the water-soluble salts of sulfated fatty alcohols. They are produced from natural or synthetic fatty alcohols containing from about 8 to 18 carbon atoms.
• Natural fatty alcohols include those produced by reducing the glycerides of naturally occurring fats and oils.
• Fatty alcohols can be produced synthetically, for example, by the Oxo process.
• suitable alcohols which can be employed in alkyl sulfate manufacture include decyl, lauryl, myristyl, palmityl and stearyl alcohols and the mixtures of fatty alcohols derived by reducing the glycerides of tallow and coconut oil.
• 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, magnesium coconut alkyl sulfate, calcium coconut alkyl sulfate, potassium coconut alkyl sulfate and
• a preferred sulfonated anionic surfactant is the alkali metal salt of secondary alkane sulfonates, an example of which is the Hostapur SAS from Hoechst Celanese.
• a second class of bleach-stable surfactant materials operable in the instant invention are the water-soluble betaine surfactants. These materials have the general formula: wherein R1 is an alkyl group containing from about 8 to 18 carbon atoms; R2 and R3 are each lower alkyl groups containing from about 1 to 4 carbon atoms, and R4 is an alkylene group selected from the group consisting of methylene, propylene, butylene and pentylene. (Propionate betaines decompose in aqueous solution and hence are not included in the instant compositions).
• betaine compounds of this type include dodecyldimethylammonium acetate, tetradecyldimethylammonium acetate, hexadecyldimethylammonium acetate, alkyldimethylammonium acetate wherein the alkyl group averages about 14.8 carbon atoms in length, dodecyldimethylammonium butanoate, tetradecyldi­methylammonium butanoate, hexadecyldimethylammonium butanoate, dodecyldimethylammonium hexanoate, hexadecyldimethylammonium hexanoate, tetradecyldiethylammonium pentanotate and tetradecyldi­propyl ammonium pentanoate.
• Especially preferred betaine surfactants include dodecyldimethylammonium acetate, dodecyldi­methylammonium hexanoate, hexadecyldimethylammonium acetate, and hexadecyldimethylammonium hexanoate.
• Nonionic surfactants useful herein include ethoxylated and/or propoxylated nonionic surfactants such as those available from BASF Corp. of New Jersey. Examples of such compounds are polyethylene oxide, polypropylene oxide block copolymers sold under the trade names Pluronic® and Tetronic® available from BASF Corp.
• Preferred members of this class are capped oxyalkylene oxide block copolymer surfactants of the following structure: where I is the residue of a monohydroxyl, dihydroxyl, or a polyhydroxyl compound; AO1, AO2, and AO3 are oxyalkyl groups and one of AO1 and AO2 is propylene oxide with the corresponding x or y being greater than zero, and the other of AO1 and AO2 is ethylene oxide with the corresponding x or y being greater than zero, and the molar ratio of propylene oxide to ethylene oxide is from about 2:1 to about 8:1; R and R′ are hydrogen, alkyl, aryl, alkyl aryl, aryl alkyl, carbamate, or butylene oxide; w is equal to zero or one; and z, x′, y′, and z′ are greater than or equal to zero.
• bleach-stable surfactants include amine oxides, phosphine oxides, and sulfoxides. However, such surfactants are usually high sudsing.
• a disclosure of bleach-stable surfactants can be found in published British Patent Application 2,116,199A; U.S. Patent 4,005,027, Hartman; U.S. Patent 4,116,851, Rupe et al; U.S. Patent 3,985,668, Hartman; U.S. Patent 4,271,030, Brierley et al; and U.S. Patent 4,116,849, Leikhim, all of which are incorporated herein by reference.
• Still other preferred bleach-stable anionic surfactants include the linear or branched alkali metal mono- and/or di-(C8 ⁇ 14) alkyl diphenyl oxide mono- and/or disulfonates, com­mercially available under the trade names Dowfax 3B-2 (sodium n-decyl diphenyloxide disulfonate) and Dowfax 2A-1. These and similar surfactants are disclosed in published U.K. Patent Applications 2,163,447A; 2,163,448A; and 2,164,350A, said applications being incorporated herein by reference.
• Detergency builders are optional materials which reduce the free calcium and/or magnesium ion concentration in a surfactant-­containing aqueous solution.
• liquid automatic dishwashing detergent compositions they are used at a level of from about 5% to about 50%, preferably from about 15% to about 40%.
• the detergency builder used in liquid automatic dishwashing detergent compositions like those of the present invention is sodium tripolyphosphate in an amount from about 10% to about 40%, preferably from about 15% to about 30%.
• a certain percentage of the sodium tripolyphosphate is in an undissolved particulate form suspended in the rest of the detergent composition.
• a phosphate ester if present in the composition, works to keep such solid particles suspended in the aqueous solution.
• the detergency builder material can be any of the detergent builder materials known in the art which include trisodium phosphate, tetrasodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, potassium pyrophosphate, potassium tripolyphosphate, potassium hexametaphosphate, sodium silicates having SiO2:Na2O weight ratios of from about 1:1 to about 3.6:1, sodium carbonate, sodium hydroxide, borax, sodium nitrilotriacetate, sodium carboxymethyloxysuccinate, sodium carboxymethyloxymalonate, polyphosphonates, salts of low molecular weight carboxylic acids, and polycarboxylates, such as poly­acrylates or polymaleates, copolymers and mixtures thereof.
• the detergent builder materials known in the art which include trisodium phosphate, tetrasodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, potassium pyrophosphat
• buffering agent materials addi­tionally serve as builders. It is preferred that the buffering agent contain at least one compound capable of additionally acting as a builder.
• An optional component of the present invention is an alkali metal salt of an amphoteric metal anion, hereinafter referred to as a metalate.
• This component can provide additional structuring to the polycarboxylate polymer thickening agent in the preferred liquid automatic dishwashing detergent composition.
• the metalate in the liquid automatic dishwashing detergent compositions of the present invention is present at a level of from 0% to about 1%, preferably from about 0.01% to about .1%.
• amphoteric metals e.g., aluminum, zinc, beryllium, tin, zirconium, titanium, etc.
• amphoteric metals e.g., aluminum, zinc, beryllium, tin, zirconium, titanium, etc.
• a preferred metalate is potassium or sodium aluminate, e.g., xM2O ⁇ yAl2O3 ⁇ zH2O, where M is K or Na.
• One method of incorporating the metalate into the preferred liquid automatic dishwashing detergent composition is by dissolving or colloidally dispersing an amphoteric metal oxide into an aqueous alkali metal hydroxide in an amount equal to or greater than one molar equivalent of the hydroxide.
• Some metalates, such as sodium aluminate, are commercially available.
• the metalate can be added into the composition at any point when the pH of the mixture is above about 10, preferably above about 11.5.
• a preferred method of incorporating the metalate into the preferred liquid automatic dishwashing detergent composition is by blending the metalate into an aqueous solution of an alkali metal silicate and then incorporating the resultant colloid with other components of the liquid automatic dishwashing detergent composition. The preferred structuring benefit is seen when the metalate is finely dispersed in the silicate such that very little or no increased turbidity is visible in the mixture.
• Formulation of these compositions with a metalate such as aluminate assures that cationic metal ions such as Al+3 are not present to precipitate silicate under such mixing conditions.
• the molar ratio of aluminum metal to SiO2 in the preferred colloidal dispersion formed should be from about 0.01:1 to about 0.1:1, preferably from about 0.02:1 to about 0.06:1, to get the best structuring benefits.
• compositions of the present invention may optionally comprise certain esters of phosphoric acid (phosphate ester).
• Phosphate esters are any materials of the general formula: wherein R and R′ are C6-C20 alkyl or ethoxylated alkyl groups.
• R and R′ are of the general formula: alkyl-(OCH2CH2) Y wherein the alkyl substituent is C12-C18 and Y is between 0 and about 4. Most preferably the alkyl substituent of that formula is C12-C18 and Y is between about 2 and about 4.
• Such compounds are prepared by known methods from phosphorus pentoxide, phosphoric acid, or phosphorus oxy halide and alcohols or ethoxylated alcohols.
• phosphate esters will generally comprise mixtures of the mono- and di-esters, together with some proportion of tri-ester.
• Typical commercial esters are available under the trademarks "Phospholan” PDB3 (Diamond Shamrock), “Servoxyl” VPAZ (Servo), PCUK-PAE (BASF-Wyandotte), SAPC (Hooker).
• Preferred for use in the present invention are KN340N and KL340N (Hoescht) and monostearyl acid phosphate (Oxidental Chemical Corp.). Most preferred for use in the present invention is Hostophat-TP-2253 (Hoescht).
• the phosphate esters useful herein provide protection of silver and silver-plated utensil surfaces.
• the phosphate ester component also acts as a suds suppressor in the anionic surfactant-containing detergent compositions disclosed herein.
• a phosphate ester component is used in the compositions of the present invention, it is generally present from about 0.1% to about 5%, preferably from about 0.15% to about 1.0% by weight of the composition.
• long chain hydroxy fatty acids Metal salts of long chain hydroxy fatty acids have been found to be useful in automatic dishwashing detergent compositions to inhibit tarnishing caused by repeated exposure of sterling or silver-plate flatware to bleach-containing automatic dishwashing detergent compositions (U.S. Patent 4,859,358, Gabriel et al).
• long chain hydroxy fatty acid is meant the higher aliphatic hydroxy fatty acids having from about 8 to about 22 carbon atoms, preferably from about 10 to 20 carbon atoms, and most preferably from about 12 to 18 carbon atoms, inclusive of the carbon atom of carboxyl group of the fatty acid, e.g., hydroxy stearic acid.
• metal salts of the long chain hydroxy fatty acids is meant both monovalent and polyvalent metal salts, particularly the sodium, potassium, lithium, aluminum, and zinc salts, e.g., lithium salts of the hydroxy fatty acids. Specific examples of this material are potassium, sodium, and particularly lithium hydroxy stearate. If the metal salts of long chain hydroxy fatty acids are incorporated into the automatic dishwashing detergent compositions of the present invention, this component generally comprises from about 0.05% to about 0.3%, preferably from about 0.05% to about 0.2% by weight of the composition.
• coloring agents and perfumes can also be added to the instant compositions to enhance their aesthetic appeal and/or consumer acceptability.
• These materials should, of course, be those dye and perfume varieties which are especially stable against degradation by high pH and/or strong active chlorine bleaching agents.
• the above-described other optional materials generally comprise no more than about 10% by weight of the total composition and are dissolved, suspended, or emulsified in the present compositions.
• a liquid automatic dishwashing detergent composition of the present invention is as follows: Ingredient % By Weight Sodium tripolyphosphate (STPP) 4.67 Tetrapotassium pyrophosphate (TKPP) 12.60 Sodium silicate, 2.4 ratio 3.27 Potassium carbonate (K2CO3) 3.91 Sodium carbonate (Na2CO3) 2.61 Available chlorine (added as NaOCl) 0.93 Potassium hydroxide (KOH) 0.84 Monostearyl acid phosphate (MSAP) 0.03 Polyacrylic acid (Sokalan PHC-25) 1.07 Al2O3 (added as sodium aluminate) 0.03 Rheology stabilizing agent (if added) 0.47 Trim KOH, to pH 12.2-12.3 0-0.3 Perfume, dye, water Balance to 100
• the polyacrylic acid is slurried into demineralized water at 3.4% by weight. All other ingredients are added in the following order while stirring with a paddle blade mixer: additional available trim water, TKPP as a 40% aqueous solution, sodium aluminate (nominally 46.8% Al2O3) about 5% in water, and KOH (45% in water added before, or premixed with, the colloidal aluminate dispersion), silicate as 47.3% solids in water, sodium and potassi­um carbonates and STPP as dry powders (essentially dissolved within five minutes), a heated 2.6% aqueous dispersion of MSAP suds suppressant, the rheology stabilizing agent.
• the acids or anhydrides are neutralized by the excess caustic already present in the composition. Heat is added during mixing up to this point so that the mixture temperature is above about 130 o F (54 o C). This temperature is maintained at least five minutes to aid in sample equilibration. After the composition has cooled to about 90 o F (32 o C) or below, the aqueous sodium hypochlorite is added as approximately 13% available chlorine. Optional perfume and colorants are added last. The composition is clear or translucent, with no visible particles or turbidity. Balance water is added, along with sufficient KOH trim to adjust the pH of the composition "as is"" to 12.2-12.3, and further KOH trim is used if needed after overnight equilibration.
• samples of the above composition exhibit an apparent Brookfield yield value of about 250 to 450 dynes/cm2, an apparent viscosity at high shear (100 rpm, Brookfield RVT #6) of about 1300 to 2000 cps, and an apparent viscosity at moderate shear (20 rpm, Brookfield RVT #6) of about 4000 to 7000 cps.
• a benzene ring with one or two carboxylic acid groups can more than double the rheological life of the above composition under such storage conditions.
• four carboxyl functions on the ring exhibit reduced benefit, and more than four carboxyls result in essentially no stability benefit.
• viscosity usually increases in the early weeks and is believed to be due to continuing polymer swelling by caustic and bleach.
• benzoic acid or substituted benzoic acids usually results in an initial lower viscosity compared to the no additive formula, but a dramatically improved storage stable formula is achieved.
• Benzoic acid and the benzoate salts are identified in published literature as potential free radical scavengers.
• Other liquid automatic dishwashing detergent compositions using known free radical scavengers are prepared approximately according to the method described in the preceding Example.
• benzoic acid or benzoate salt With the addition of benzoic acid or benzoate salt, the available chlorine decays at about the same rate or slower, compared to the no-additive control.
• Most other free radical scavengers degrade the activity of the hypochlorite bleach when placed in storage tests in the formula context of the previous example. % of Initial Value Remaining Rheology Stabilizing Agent Viscosity Av.
• Example II Various levels of benzoic acid (prospective rheology stabilizing agent) are tested following the method of preparation in Example I. Also, these samples are screened in the rapid aging stability test as described above. Viscosity stability as a function of storage time is shown: Benzoic Acid Level Initial Viscosity % of Initial Viscosity After: (Centipoise) 1 Week 2 Weeks 3 Weeks 4 Weeks 6 Weeks None 1900 112% 14% ** 0.1% 3540* 108% 92% 14% ** 0.2% 1830 107% 113% 91% 66% ** 0.5% 1760 114% 111% 122% 101% 69% 0.7% 1300 145% 101% 84% 68% 94% 1.0% 1430 130% 134% 158 122% 105% *This sample only at 1.21% polyacrylic acid vs. 1.07% in other samples. **Measured below 10% of initial viscosity, or approaching water-thin by appearance.
• the degree of increased rheological stability desired in a composition can be achieved by adjustment of the level of benzoate compound added to the formulation, realizing that higher levels can adversely affect initial composition viscosity.
• liquid automatic dishwashing detergent compositions are as follows:
• Viscosity stability as a function of time in 120 o F (49 o C) is summarized.
• Composition Initial Viscosity % of Initial Viscosity After: (Centipoise) 1 Week 2 Weeks 3 Weeks 4 Weeks A-1 1380 130% 36% * * A-2 1480 121% 105% 95% 100% B-1 2960 90% * B-2 4320 114% 87% 88% 72% *Measured viscosity below 10% of initial, or approaching water-thin by appearance.
• the degree of stabilization benefit achieved with the addition of benzoic acid depends on the type of polymer used in the composition. Both the degree of benefit and the rate of degradation of viscosity without the benzoate additive are thought to be dependent on the amount or type of cross-linking component and/or presence of other minor components in the particular polymer stock. Nevertheless, there is some degree of improvement in rheological stability seen with all polymer stocks tested.
• Substituted benzoic acids are placed into the compositions of Example I (less the MSAP) as candidate rheology stabilizers and are subjected to the same stress stability testing in light-shielded bottles at 120 o F (49 o C).
• the hydroxybenzoic samples lose all available chlorine by day one, so no viscosity readings are considered relevant beyond that point.
• toluic acid is a preferred rheology stabilizer, and it appears that a meta isomer may be a preferred positional configuration.
• Liquid cleaning compositions of the present invention are as follows: Formula Parts, % of Active Ingredient Ingredient A-1 A-2 B-1 B-2 C-1 C-2 Sodium silicate solids, 2.4 ratio 2.50 2.50 2.50 2.50 2.50 Available chlorine (added as NaOCl) 1.00 1.00 1.00 1.00 1.00 1.00 1.00 KOH trim to pH shown below 0-2 0-2 0-2 0-2 0-2 0-2 Acetic acid, glacial 0 0 0 0 0.50 0.50 Polyacrylic acid (Sokalan PH25) 1.30 1.30 1.25 1.25 1.00 1.00 Benzoic acid (stabilizing agent) 0 0.50 0 0.50 0 0.50 Water -----------Balance to 100----------- Composition pH, measured as-is 12.0 12.0 11.0 11.0 10.3 10.3 Initial apparent viscosity, cps 1410 1070 1400 1220 4290 5680 Initial apparent yield value, dynes/cm2 72 88 108 88 * * *Note: The
• compositions are clear to translucent gels and are useful for hard surface cleaning and similar applications.
• the compositions containing benzoic acid as a rheology stabilizing agent are able to retain viscosity and yield value (80% of initial values or higher) for a longer time under stress storage than the compositions without the stabilizing agent.
• Benzoic acid and other rheology stabilizing agents of the invention result in a lower initial viscosity as indicated above, but the stabilization effect over time more than compensates for a lower initial viscosity.

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