05/341489

10/21/1975

03/15/1973

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Colgate-Palmolive Company (New York, NY)

510/424

510/341, 516/15, 516/920, 510/342, 510/339, 516/909, 510/429, 510/340, 510/394, 510/423, 516/914, 510/427, 510/325

C11D1/22; C11D1/29; C11D1/72; C11D1/83; C11D3/33; C11D11/00; C11D17/00; C11D1/75; C11D1/02; C11D3/26; C11D1/75; C11D1/29; C11D3/33; C11D1/72

252/546,543,DIG.14,DIG.11,89O,89B,DIG.1

Lovering, Richard D.

Miller, Richard Cornell Ronald Sylvester Herbert N. S. S.

What is claimed is

1. A method of preparing a clear, heavy-duty liquid detergent composition free of phosphates in the absence of heat and without gel formation which comprises the steps of (a) mixing a synthetic organic detergent selected from the group consisting of ethylene oxide condensate nonionic detergents, C₁₀ -C₂₀ alkyl polyethoxy sulfates of the formula RO(C₂ H₄ O)_n SO₃ M wherein n is 2 to 6 and M is sodium, potassium, ammonium, lower alkylamino or lower alkanolamino, mixtures thereof; and mixtures of said nonionic detergents or said alkyl polyethoxy sulfates with water-soluble C₁₀ -C₁₆ alkyl benzene sulfonates or amine oxides having the formula R₁ R₂ R₃ N➝ O wherein R₁ is an alkyl of 10 to 16 carbon atoms and R₂ and R₃ are each methyl or ethyl, with an organic solvent selected from the group consisting of C₂ -C₃ alkanols and ethylene glycol monoethyl ether to form a first solution; (b) forming a solution of sodium or potassium nitrilotriacetate in water; and (c) admixing the first solution with said nitrilotriacetate solution to form a clear liquid detergent consisting essentially of 5% to 30% by weight of said detergent, 2% to 15% by weight of said solvent, 5% to 25% by weight of said nitrilotriacetate and the balance water.

2. A method according to claim 1 wherein optical brighteners soluble in said solvent are dissolved in said first solution, said brighteners being present in an amount of 0.2% to 2% by weight of said liquid detergent composition.

3. A method according to claim 2 wherein said optical brighteners are dissolved in an organic solvent selected from the group consisting of C₂ -C₃ alkanols and ethylene glycol monoethyl ether to form a second solution and said second solution is admixed with said first solution prior to being admixed with said aqueous nitrilotriacetate solution.

4. A method according to claim 1 wherein said detergent is a condensate of a C₈ -C₂₂ alkanol with 6 to 30 moles of ethylene oxide.

5. A method according to claim 1 wherein said detergent is a mixture of a condensate of a C₈ -C₂₂ alkanol with 6 to 30 moles of ethylene oxide and a second detergent selected from the group consisting of said alkyl polyethoxy sulfate, said alkyl benzene sulfonate and said amine oxide and said first solutions includes water.

6. A method according to claim 5 wherein said detergent is a mixture of said condensate and said polyethoxy sulfate, said detergents being present in approximately equal amounts by weight.

7. A method according to claim 1 wherein water is included in said first solution.

8. A method according to claim 7 wherein a water-soluble hydrotrope selected from the group consisting of C₁ -C₃ alkyl substituted benzene sulfonates and C₅ -C₆ alkyl sulfates is included in said first solution.

9. A method according to claim 3 wherein said solution of said nitrilotriacetate is prepared by adding nitrilotriacetic acid to an aqueous solution of water-soluble hydroxide to neutralize said acid and said first solution and said second solution is added to said nitriloacetate solution with agitation, thereby forming said liquid detergent.

BACKGROUND OF THE INVENTION

This invention relates to a novel method for preparing heavy-duty, clear, liquid detergents.

Eutrophication is the process of enrichment of waters with nutrients such as carbon, nitrogen, phosphorus, potassium, iron, trace metals, and vitamins. Factors in the eutrophication of lakes, streams, and estuaries are natural runoff, agricultural drainage, ground water, precipitation, sewage, and waste effluents.

Although there is presently no adequate proof, it has been postulated that the phosphorus containing builders present in detergent compositions can be a factor in eutrophication. Therefore, any substitutes which do not contain phosphorus may decrease eutrophication to some extent.

Currently, synthetic detergent formulations contain large amounts of phosphate salts, primarily in the form of polyphosphates and orthophosphates. The phosphates have been found to be highly effective soil-removing agents when combined with all types of synthetic detergents, which has accounted for their great popularity in detergent compositions.

In an attempt to formulate detergent compositions free of phosphates, the use of alternative sequestrants has been explored to a limited extent. One of the most promising of these sequestrants is the water-soluble salts of nitrilotriacetic acid. Additionally, increasing use is being made of surfactants which are less unfavorably affected by hard water, particularly synergistic mixtures of surfactants.

Many of the synthetic surfactants have demonstrated a high efficiency in removing oily soil from fabrics and substrates under ideal conditions. However, when these surfactants are used alone in hard water, a significant part of the visible soil is not removed. This is particularly apparent in actual usage such as repeated launderings of the same laundry items with the same phosphate-free compositions.

SUMMARY OF THE INVENTION

It has now been discovered that clear, heavy-duty liquid detergent products can be formulated from synergistic mixtures of synthetic detergents including amine oxides, nonionic surfactants, and anionic surfactants, with builder salts comprising water-soluble salts of nitrilotriacetic acid. A method has been discovered whereby these products can be easily prepared without formation of undesirable gels. The formation of a gel requires a considerable amount of time and heat to destroy the gel and prepare a flowable product.

The detergent formulations of the present invention exhibit many desirable characteristics with regard to both physical properties and performance in use. As to physical properties, the compositions are homogeneous, pourable, and free-flowing from the container as manufactured and after aging. They exhibit a high degree of stability upon storage at normal room temperature of the order of about 70°F. over a period of many months without any appreciable precipitation or formation of immiscible layers. They can be subjected to elevated temperatures of the order of 110°F. or cooled to 40°F., and the liquid is in a clear, homogeneous form when returned to room temperature. As a result, the consumer can utilize the compositions conveniently by the addition of small portions to a dishpan or laundering bath, and the detergent and builder salts will be present in constant composition in each portion. While adjuvant materials may be added which render the final product translucent or opaque as desired, the requirement for a clear solution of the main ingredients insures that effective foam and washing power will be obtained with each portion, and promotes the stability and homogeneity of the product. The liquid may be packaged in any suitable container or packaging material, such as metal, plastic, or glass in the form of bottles, bags, cans, or drums.

In performance, the detergent compositions of the present invention exhibit a particularly high level of washing power and foaming action during dishwashing, laundering, and other cleaning operations. A particular advantage of these compositions is their high detergent and emulsification power for cleaning of soiled surfaces containing fats and greases, including soiled aluminum and other metals, ceramic materials, wearing apparel, and the like. The detergents exhibit a good volume of foam initially and during the cleansing operation.

The preferred nonionic surfactants for use in the present invention are the low-foaming ethylene oxide condensate types of nonionic detergents. Examples thereof are the polyalkylene oxide ethers of high aliphatic alcohols. Suitable alcohols are those having a hydrophobic character, and preferably from 8 to 22 carbon atoms. Examples thereof are iso-octyl, nonyl, decyl, dodecyl tridecyl, tetradecyl, hexadecyl, octadecyl, and oleyl alcohols which may be condensed with an appropriate amount of ethylene oxide, such as at least 6, and preferably about 10-30 moles. A typical product is tridecyl alcohol, produced by the Oxo process, condensed with about 12, 15, or 20 moles of ethylene oxide. The corresponding higher alkyl mercaptono or thioalcohols condensed with ethylene oxide are also suitable for use in compositions of the present invention.

Other nonionic surfactants which can be used in the present invention are the reaction products of benzyl chloride and ethoxylated alkyl phenol having the formula ##EQU1## where R is alkyl chain having from 6 to 12 carbon atoms and x is a whole number from 12 to 20; polyether esters of the formula

where x is an integer from 4 to 20 and R is a lower alkyl group of not over four carbon atoms, e.g., a compound of the formula

and polyalkylene oxide condensates of an alkyl phenol, such as the polyglycol ethers of alkyl phenols having an alkyl group of at least about 6 and usually about 8 to 20 carbon atoms and an ethylene oxide ratio (number of ethenoxy groups per mole of condensate) of about 7.5, 8.5, 11.5, 20.5, 30, and the like. The alkyl substituent on the aromatic nucleus may be di-isobutylene, diamyl, polymerized propylene, isooctyl, nonyl, dimerized C ₆ -C ₇ -olefin, and the like. Among other condensates with phenols is an alkylated B-naphthol condensed with 8 moles of ethylene oxide, the alkyl group having 6 to 8 carbon atoms.

Further suitable detergents are the polyoxyalkylene esters of organic acids, such as the higher fatty acids, rosin acids, tall oil, or acids from the oxidation of petroleum, and the like. The polyglycol esters will usually contain from about 8 to about 30 moles of ethylene oxide or its equivalent and about 8 to 22 carbon atoms in the acyl group. Suitable products are refined tall oil condensed with 16 or 20 ethylene oxide groups, or similar polyglycol esters of lauric, stearic, oleic and the like acids.

Additional suitable non-ionic detergents are the polyalkylene oxide condensates with higher fatty acid amides, such as the higher fatty acid primary amides and higher fatty acid mono- and di-ethanol-amides. Suitable agents are coconut fatty acid amide condensed with about 10 to 30 moles of ethylene oxide. The fatty acyl group will similarly have about 8 to 22 carbon atoms, and usually about 10 to 18 carbon atoms in such products. The corresponding sulfonamides may also be used if desired.

The water soluble polyoxyethylene condensates with polyoxypropylene polymers may likewise be employed in compositions of the present invention. The polyoxypropylene polymer, which is prepared by condensing propylene oxide with an organic compound containing at least one reactive hydrogen, represents the hydrophobic portion of the molecule, exhibiting sufficient water insolubility per se, at a molecular weight of at least about 900, such as about 900 to 2400, and preferably about 1200 to 1800. The increasing addition or condensation of ethylene oxide on a given water insoluble polyoxypropylene polymer tends to increase its water solubility and raise the melting point such that the products may be water soluble, and normally liquid, paste or solid in physical form. The quantity of ethylene oxide varies with the molecular weight of the hydrophobic unit but will usually be at least about 20% and preferably at least about 40% by weight of the product. With an ethylene oxide content of about 40 up to 50%, there are usually obtained normally liquid products, above 50% soft wax-like products, and from about 70-90% normally solid products may be obtained which can be prepared in flake form if desired. These condensates may be designated by the following structure:

where

Y is the residue of an organic compound which contained x active hydrogen atoms.

n is an integer

x is an integer, the value of n and x being such that the molecular weight of the compound, exclusive of E, is at least 900, as determined by hydroxy number, E is a polyoxyethylene chain and constitutes 20-90% by weight of the compound, and H is hydrogen.

It is preferred to use products of the type just described having a total molecular weight within the range of 2000 to 10,000, and preferably about 4000 to 8000. A suitable material is a condensate having a typical average molecular weight of about 7500, the hydrophobic propylene glycol being condensed with sufficient ethylene oxide until a normally solid water-soluble product is obtained which has an ethylene oxide content of about 80-90% and a melting point of about 51°-54°C. Another suitable material is a liquid condensate having an ethylene oxide content of 40-50% and a molecular weight of about 4500.

A preferred anionic detergent for use in compositions of the present invention is a higher fatty alkyl polyethoxy sulfate of the formula RO(C ₂ H ₄ O) _n SO ₃ M, wherein R is a fatty alkyl of from 10 to 20 carbon atoms, n is a number from 2 to 6, n being from 1/5 to 1/3 of the number of carbon atoms in r, and M is a solubilizing, salt-forming cation such as sodium, potassium, ammonium, lower alkylamino, lower alkanolamino, etc. This anionic detergent is most readily biodegradable and has better detergency when the fatty alkyl group is terminally joined to the polyoxyethylene chain which, of necessity, is also terminally joined to the sulfur in the sulfate group. Although a slight amount of branching of the higher alkyl may be tolerated, to the extent of not more than 10% of the carbon atom content of the alkyl not being in a straight carbon chain, generally even this minor deviation from linear structure is to be avoided. Also, medial joinder of the alkyl to the ethoxy chain should be minimal, i.e. less than 10%, and even such joinder should preferably be concentrated near the end of the alkyl chain. Within the 10 to 20 carbon atom alkyl groups, the preferred alkyls are of 12 to 15 carbon atoms and those most preferred are the mixed alkyls containing 12, 13, 14, and 15 carbon atom chains. The mixture is preferably one with at least 10% of each chain length and no more than 50% of any one chain length.

The ethylene oxide content of the anionic detergent is such that n is from 2 to 6 and preferably from 2 to 4 and generally averaging about 3, especially when R is a mixed 12 - 15 carbon atom alkyl mixture. To maintain a desired hydrophiliclipophilic balance when the carbon content of the alkyl chain is in the lower portion of the 10 - 20 range,, the ethylene oxide content might be reduced so that n is about 2, whereas when R is in the range of from 16 to 18 carbon atoms, n may be within the range of from 4 to 6.

The salt-forming cation may be any suitable solubilizing metal or radical but will most frequently be an alkali metal cation or an ammonium cation. If alkylamine or lower alkanolamine groups are present, alkyls and alkanols thereof usually contain 1 to 4 carbon atoms and the amines and alkanolamines may be mono-di- or tri-substituted, i.e. monoethanolamine, diisopropanolamine, trimethylamine, etc.

The importance of using the correct anionic detergent in the present composition is shown by the failure of corresponding alcohol sulfates of similar liquid detergent compositions to wash as well as the present compositions containing the higher alcohol ethylene oxide sulfates. For example, a higher alcohol sulfate in which the alcohol is a mixed 12 - 15 carbon atoms alcohol, exhibits a significantly poorer detergency than the compositions of the present invention. Even within the preferred range of alcohol polyethoxy sulfates, an improvement in detergency is noted for compositions which include a mixed 12 - 15 carbon atoms alcohol polyethoxy sulfate when compared to other higher alkyl ethoxy sulfates such as a mixed 14 - 15 carbon atoms polyethoxy sulfate of the same ethoxy chain length. The preferred detergent is available from Shell Chemical Company and identified by them as Neodol 25-3S, the sodium salt normally sold as a 60% active material including about 40% of the aqueous solvent medium, of which a minor proportion is ethanol. Although this material is the sodium salt, the potassium and other suitable soluble salts may be utilized either in partial or complete substitution for that of sodium.

Examples of the higher alcohol polyethoxy sulfates which may be utilized as the anionic detergent constituent of the present liquid detergent composition or as partial substitutes for the above-noted preferred anionic detergent include: mixed C ₁₂ -15 normal primary alkyl triethenoxy sulfate, sodium salt; myristyl triethenoxy sulfate, potassium salt; n-decyl diethenoxy sulfate, diethanolamine salt; lauryl diethenoxy sulfate, ammonium salt; palmityl tetraethenoxy sulfate, sodium salt; mixed C ₁₄ -15 normal primary alkyl mixed tri- and tetraethenoxy sulfate, sodium salt; stearyl pentaethenoxy sulfate, trimethylamine salt and mixed C ₁₀ -18 normal primary alkyl triethenoxy sulfate, potassium salt. Minor proportions of the corresponding branched chain and medially alkoxylated detergents, such as those described above but modified to have ethoxylation at a medial carbon atom, e.g., one located four carbons from the end of the chain, may be employed but the carbon atom content of the higher alkyl will be the same. Similarly, the joinder of a normal alkyl may be at a secondary carbon one or two carbon atoms removed from the end of the chain. In either case, only the minor proportions previously mentioned will be present.

Additional useful anionic surface active agents include those surface active or detergent compounds which contain an organic hydrophobic group and an anionic solubilizing group. Typical examples of anionic solubilizing groups are sulfonate, sulfate, carboxylate, phosphonate and phosphate. Examples of suitable anionic detergents which fall within the scope of the invention include soaps such as the water sluble salts of higher fatty acids or rosin acids such as may be derived from fats, oils and waxes of animal, vegetable or mineral origin e.g. the sodium soaps of tallow, grease, coconut oil, tall oil and mixtures thereof; and the sulfates and sulfonated synthetic detergents particularly those having at least 8 and about 8 to 30, and preferably about 12 to 22 carbon atoms, in the molecular structure.

As examples of suitable, synthetic anionic detergents there may be cited the higher-alkyl mononuclear aromatic sulfonates such as the higher-alkyl benzene sulfonates containing from 10 to 16 carbon atoms in the alkyl group in a straight or branched chain e.g. the sodium salts of higher-alkyl benzene sulfonates or of the higher-alkyl toluene, xylene, and phenol sulfonates; alkyl naphthalene sulfonate, ammonium diamyl naphthalene sulfonate, and sodium dinonyl naphthalene sulfonate. Mixed long chain alkyls derived from coconut oil, fatty acids and the tallow fatty acids can also be used along with cracked paraffin wax olefins and polymers of lower monoolefins. In one preferred type composition there is used a linear alkyl benzene sulfonate having a high content of 3-(or higher) phenyl isomers and a correspondingly low content (well below 50%) of 2- (or lower) phenyl isomers; in other terminology the benzene ring is preferably attached in large part at the 3 or higher (e.g. 4, 5, 6, or 7) position of the alkyl group and the content of isomers at which the benzene ring is attached at the 2 or 1 position is correspondingly low.

Other anionic detergents are the olefin sulfonates including long chain alkene sulfonates, long chain hydroxy alkane sulfonates or mixtures of alkene-sulfonates and hydroxy alkane sulfonates. These olefin sulfonate detergents may be prepared in known manner by the reaction of SO ₂ with long chain olefins (of 8-25 and preferably of 12-21 carbon atoms) of the formula RCH=CHR ₁ , where R is alkyl and R ₁ is alkyl or hydrogen to produce a mixture of sultones and alkene sulfonic acids which mixture is then treated to convert the sultones to sulfonates. Especially good characteristics are obtained by the use of a feed stock containing a major proportion i.e. above 70%, and preferably above 90%, of alpha olefins. Examples of such products are C ₁₄ alpha olefin sulfonate, C ₁₆ alpha olefin sulfonate, etc. Examples of other sulfate or sulfonate detergents are paraffin sulfonates, such as the reaction products of alpha olefins and bisulfites (e.g. sodium bisulfite), e.g. primary paraffin sulfonates of about 10-20, preferably about 15-20 carbon atoms; e.g. sodium n-pentadecane sulfonate, sodium n-octadecyl sulfonate, sulfates of higher alcohol; salts of alphasulfo fatty esters (e.g. of about 10-20 carbon atoms, such as metal alpha-sulfo myristate or alphasulfo tallowate).

Examples of sulfates of higher alcohols are sodium lauryl sulfate, sodium tallow alcohol sulfate; turkey red oil or other sulfated oils, or sulfates of mono- or diglycerides of fatty acids (e.g. stearic monoglyceride monosulfate), lauryl or other higher alkyl glycerol ether sulfonates; aromatic poly (ethyeneoxy) ether sulfates such as the sulfates of the condensation products of ethylene oxide and nonyl phenol (e.g. having 1-10 etheneoxy groups per molecule and usually from 2-10 such groups.).

The suitable anionic detergents include also the acyl sarcosinates (e.g., sodium lauroyl sarcosinate), the acyl esters (e.g. oleic acid ester) of isothionates, and the acyl N-methyl taurides (e.g. potassium N-methyl lauroyl or oleoyl tauride). In each instance the acyl moieties usually vary from fatty C ₁₀ to C ₂₀ and preferably C ₁₂ to C ₁₆ .

The most highly preferred water soluble anionic detergent compounds are the ammonium and substituted ammonium (such as mono, di and triethanolamine), alkali metal such as sodium and potassium and alkaline earth metal (such as calcium and magnesium) salts of the higher alkyl benzene sulfonates, olefin sulfonates and higher alkyl sulfates, and the higher fatty acid monoglyceride sulfates. The particular salt will be suitably selected depending on the particular formulation and the proportions therein. Mixtures of various cations can also be used.

Amine oxides, additional surface active agents found useful in the present formulations, are compounds of the general formula R ₁ R ₂ R ₃ N➝O. The arrow is a conventional representation of a semi-polar bond. They are generally prepared by the direct oxidation of the appropriate tertiary amine. When R ₁ is a much longer chain than R ₂ and R ₃ , amine oxides have valuable surfactant properties. For the purpose of this invention, R ₁ is an alkyl radical having from 10 to 16 carbon atoms. Desirable surface active properties are lost if R ₁ has substantially fewer than 10 carbon atoms, and solubility in the present formulation is too low if R ₁ has more than 16 carbon atoms. R ₂ and R ₃ are each selected from the group consisting of methyl and ethyl radicals. Preferably R ₁ is a dodecyl radical or a mixture of dodecyl with decyl and tetradecyl radicals. R ₂ and R ₃ are preferably methyl radicals. Formulas of this invention containing amine oxide at a level of the order of seven percent produce surprisingly high suds levels and are effective detergents. Too little amine oxide does not contribute sufficient detergent performance to the formulations, and too much interferes with achieving the builder and the detergents in sufficient amounts in a homogeneous liquid.

The inclusion of a water-soluble sulfonated hydrotropic substance is effective in promoting the compatibility of the ingredients so as to form a homogeneous liquid product. Suitable materials are the alkali metal organic sulfonated (including sulfated) salts having a lower alkyl group of up to about six carbons. It is preferred to employ an alkyl aryl sulfonate having up to three carbons in a lower alkyl group such as the sodium and potassium xylene, toluene, ethylbenzene, and isopropyl benzene sulfonates. Sulfonates made from exylene include orthoxylene sulfonates, metaxylene sulfonates, paraxylene sulfonates, and ethylbenzene sulfonates. Commercial xylene sulfonates usually contain metaxylene sulfonate as the main ingredient. Analyses of typical commercial products show about 40-50 % metaxylene sulfonate, 10-35% orthoxylene sulfonate, and 15-30% paraxylene sulfonate with 0-20% ethylbenzene sulfonate. Any suitable isomeric mixture may be employed, however. Suitable lower alkyl sulfate salts having about five to six carbons in the alkyl group may be employed such as the alkali metal n-amyl and n-hexyl sulfate. The use of an amount of hydrotropic material in excess of the amount required to effect a single liquid phase is not helpful, since it tends to add additional salt to an already concentrated system.

A minor amount of a water-soluble organic solvent may be employed as part of the aqueous solubilizing medium. Suitable solvents include water-soluble saturated aliphatic monohydric alcohols of two to three carbon atoms, as well as alkylene glycol monoethyl ethers. Examples thereof include ethanol, propanol, isopropanol, and ethylene glycol monoethyl ether. The solvent may serve a multiplicity of functions. It can provide for improved physical properties such as a lower cloud point, improve low temperature aging, modify the viscosity, and the like. In certain cases, a small amount of solvent in combination with the hydrotrope will produce a clear liquid which will otherwise be cloudy at room temperature. The suitable amount of solvent which may be employed varies with the particular formulation, since an excessive amount tends to result in separation of the product into two or more phases.

Sodium or potassium nitrilotriacetate, also referred to as NTA, has been found to be an exceptionally effective sequestering agent for detergent compositions. The outstanding chemical characteristic of NTA in detergent formulations is its ability to remove many of the hard-water, heavy-metal cations, which interfere with detergency, from solution by forming soluble chelate compounds. This action, the removal of an ion without precipitation or adsorption, is generally referred to as sequestering. From a practical point of view, the sequestering action of NTA is similar to that of the polyphosphates, and in many cases the two substances produce practically the same effect. NTA has one great advantage over the condensed phosphates in that it does not tend to decompose or hydrolyze in aqueous solution. It can, therefore, be successfully used in aqueous compositions such as liquid detergents.

The sequestering action of NTA (or any other sequestering agent) on a heavy metal cation is an equilibrium reaction and may be represented by the following equation, where M ⁺² is a generic heavy metal cation:

The equilibrium concentration of M ⁺² is a measure of the sequestering power of the sequestering agent. For any sequestrant, this equilibrium concentration depends not only on the concentration of the sequestering agent, but also on the pH of the solution and on the chemical identity of the metal ion. In the case of salts of nitrilotriacetic acid, the degree to which metals are sequestered also depends on the particular salt of nitrilotriacetic acid which is used. The trisodium and tripotassium salts have been found to be most effective in detergent compositions. For compositions of the present invention, the tripotassium salt is preferred for reasons of solubility.

Examples of other builder salts which may be included in the compositions of the present invention include alkali metal carbonates, silicates, oxydiacetates, polycarboxylates, hydroxyethyl iminodiacetates, and mixtures thereof. These additional builders are used to enhance detergency in hard water as well as in cool water.

Various other ingredients may be added as desired, including compatible perfumes, coloring materials, corrosion or tarnish inhibitors, germicides, bleaching agents, optical bleaches or fluorescent dyes, viscosity modifiers, or additional solvent materials, and the like.

The improved method of preparing the detergent compositions of the present invention requires no heat, but it is essential that the ingredients be added in the correct order to prevent gel formation and the greatly increased production costs attending gel formation.

In the first step of the process of the present invention, the surfactant is dissolved in the desired solvent system. The surfactant may be a nonionic, anionic, amine oxide surfactant, or any combination of these. A hydrotrope may be used to enhance the solubility of the surfactant in the solvent system.

In the second step of the process, the optical brighteners are dissolved in an organic solvent. Some of the surfactant may be used in this second solution. Potassium hydroxide may be added to raise the pH of the solution and thus enhance solubility.

The surfactant solution and the brightener solution are then combined. Nitrilotriacetic acid is added slowly to potassium hydroxide to neutralize the nitrilotriacetic acid, and the resulting potassium nitrilotriacetate, along with any other builder salts used, is combined with the mixture of the surfactant and optical brighteners. The resulting mixture forms a stable detergent solution with no gelling.

The total concentration of surfactant used in the compositions of the present invention may range from about 5% to about 30%, by weight with an optimal range being from about 10% to about 20% by weight. Where mixtures of surfactants are used, they are preferably used in approximately equal amounts by weight. The optical brighteners are present in amounts ranging from about 0.2% to about 2%, and preferably from 0.5% to 1.5%, by weight of the total composition.

The soluble salt of nitrilotriacetic acid is present in amounts ranging from about 5% to about 25% by weight, and preferably in amounts ranging from about 8% to about 15% by weight of the total composition.

The organic solvent system may range from about 2% to about 15% of the total composition by weight, and preferably from about 5% to about 10% by weight.

The hydrotrope concentration may range from about 0% to about 10% by weight, with a preferred range being from about 3% to about 7% by weight of the total composition.

Where builder salts in addition to the salts of nitrilotriacetic acid are used, their concentrations may vary from about 1% to about 15% by weight of the total composition, and preferably from about 2% to about 10% by weight.

The method of the present invention is of particular value in preparing clear liquid detergent compositions because all of the mixing takes place at room temperature, thus obviating the necessity of applying heat to the mixture. No special heating equipment is required for preparing the liquid detergent compositions of the present invention. If the components are added in the correct order, no gelling occurs when the various ingredients are combined. Gelling is particularly undesirable because of the loss of man-hours and resulting increased costs in un-gelling the mixture by heating. This expensive loss of time can be prevented by employing the novel method of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

EXAMPLE I

A heavy-duty, clear, liquid laundry detergent was prepared as follows:

Solution A was made up by mixing together the following ingredients:

Parts by Weight Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 7.0 Sodium salt of a sulfated 3 mole ethylene oxide adduct of a C ₁₂ -C ₁₅ linear alcohol 7.0 Ethanol 1.0 Ethylene glycol monoethyl ether 3.75 Potassium xylene sulfonate 4.0

Solution B was formulated from the following ingredients:

Parts by Weight Ethanol 2.75 Optical brighteners 1.16 Potassium hydroxide 1.0 Perfume 0.15

Solutions A and B were mixed and were added slowly with stirring to 12.00 parts by weight of potassium nitrilotriacetate dissolved in 60.39 parts by weight of water. All of the mixing was done at room temperature, and there was no gelling of the solutions at any time.

EXAMPLE II

A heavy-duty, clear, liquid laundry detergent was prepared as follows:

Solution A was prepared by mixing together the following ingredients:

Parts by Weight Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 7.0 Sodium dodecyl benzene sulfonate 7.0 Isopropanol 1.0 Ethylene glycol monoethyl ether 3.75 Potassium xylene sulfonate 4.0

Solution B was formulated from the following:

Parts by Weight Isopropanol 2.75 Optical brighteners 1.16 Perfume 0.15 Potassium hydroxide 1.0

Solutions A and B were mixed and were added slowly with stirring to 10.0 parts by weight of potassium nitrilotriacetate dissolved in 62.39 parts by weight of water. All mixing was done at room temperature, and there was no gel formation in any of the steps of preparing this liquid detergent formulation.

EXAMPLE III

A heavy-duty, clear, liquid laundry detergent was prepared as follows:

Solution A was made up by mixing together the following ingredients:

Parts by Weight Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 7.0 Dodecyl dimethyl amine oxide 7.0 Ethanol 1.0 Ethylene glycol monoethyl ether 5.0

Solution B was formulated from the following ingredients:

Parts by Weight Ethanol 1.5 Optical brighteners 1.16 Potassium hydroxide 1.0 Perfume 0.15

Solutions A and B were mixed and were added slowly with stirring to 10.00 parts by weight of potassium nitrilotriacetate dissolved in 66.39 parts by weight of water. All mixing was conducted at room temperature; no gel was formed at any step of the procedure.

EXAMPLE IV

A heavy-duty, clear, liquid detergent was prepared as follows:

Solution A was prepared by mixing together the following ingredients:

Parts by Weight Sodium salt of a sulfated 3 mole ethylene oxide adduct of a C ₁₂ -C ₁₅ linear alcohol 7.0 Alkyl (12-14 carbon chain) dimethyl amine oxide 7.0 Isopropanol 1.0 Ethylene glycol monoethyl ether 5.0

Solution B was formulated from the following:

Parts by Weight Isopropanol 1.5 Optical brighteners 1.16 Perfume 0.15 Potassium hydroxide 1.0

Solutions A and B were mixed and were added slowly with stirring to 12.0 parts by weight of potassium nitrilotriacetate dissolved in 64.39 parts by weight of water-all mixing was done at room temperature, and there was no gel formation in any of the steps of preparing the above liquid detergent formulation.

EXAMPLE V

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Water 62.5 Potassium dodecyl benzene sulfonate 110.0 Potassium xylene sulfonate (40%) 50.0 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 35.0

Solution B was formulated from the following:

Grams Ethanol 37.5 Optical brighteners 2.3

Solutions A and B were mixed together and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide 2.5 Water 97.2 Sodium nitrilotriacetate 100.0 Perfume 1.5 Color 1.5

EXAMPLE VI

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Water 125.0 Potassium xylene sulfonate 100.0 Sodium salt of a sulfated 3 mole ethylene oxide adduct of a C ₁₂ -C ₁₅ linear alcohol (60%) 116.6

Solution B was prepared from the following:

Grams Isopropanol 75.0 Optical brighteners 4.6 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 70.0

Solutions A and B were mixed together and the mixture was added slowly to the following mixture:

Grams Potassium hydroxide 127.0 Water 316.0 Nitrilotriacetic acid 62.5 Perfume 1.5 Color 1.5

The cloud clear point of the resulting clear liquid detergent was 125°F.

EXAMPLE VII

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

A solution was prepared by mixing together the following ingredients:

Grams Water 400.0 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 260.0 Ethanol 150.0 Optical brighteners 9.2 Potassium hydroxide (45%) 5.0

The above solution was added slowly to the following mixture:

Grams Potassium hydroxide (45%) 170.0 Water 897.8 Nitrilotriacetic acid 90.0 Perfume 3.0 Color 1.5

The cloud clear point of the above liquid detergent was 128°F.

EXAMPLE VIII

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Water 400.0 Isopropanol 75.0 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 260.0

Solution B was prepared from the following:

Grams Isopropanol 75.0 Optical brighteners 8.2 Potassium hydroxide (45%) 5.0

Solutions A and B were mixed together and the mixture was added slowly with stirring to the following mixture:

Grams Water 909.8 Nitrilotriacetic acid 90.0 Perfume 3.0 Color 3.0 Potassium hydroxide (45%) 170.0

The cloud clear point of the above liquid detergent was 121°F.

EXAMPLE IX

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Water 250.0 Potassium xylene sulfonate 200.0 Potassium dodecyl benzene sulfonate 246.0 Optical brighteners 8.0

Solution B was prepared from the following:

Grams Isopropanol 75.0 Ethylene glycol monoethyl ether 75.0 Optical brighteners 1.2 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 140.0

Solutions A and B were mixed together and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide 250.0 Water 611.8 Nitrilotriacetic acid 125.0 Perfume 3.0 Color 3.0

EXAMPLE X

A heavy duty, clear liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Ethylene glycol monoethyl ether 50.0 Isopropanol 25.0 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 130.0 Optical brighteners 0.6

Solution B was prepared from the following:

Grams Water 200.0 Optical brighteners 4.0 Potassium hydroxide (45%) 2.5

Solutions A and B were mixed together and the mixture was added slowly with stirring to the following mixture:

Grams Water 448.9 Potassium hydroxide (45%) 85.0 Nitrilotriacetic acid 45.0 Perfume 1.5 Color 7.5

The cloud clear point of the above liquid detergent was 134°F.

EXAMPLE XI

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Water 25.0 Potassium xylene sulfonate (40%) 20.0 Sodium salt of a sulfated 3 mole ethylene oxide adduct of a C ₁₂ -C ₁₅ linear alcohol (60%) 23.33 Optical brighteners 0.8

Solution B was prepared from the following:

Grams Isopropanol 7.5 Optical brighteners 0.12 Ethylene glycol monoethyl ether 7.5 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 14.0

Solutions A and B were mixed together and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide 29.0 Water 56.45 Nitrilotriacetic Acid 14.5 Perfume 0.3 Color 1.5

The cloud clear point of the above liquid detergent was between 149° and 151°F.

EXAMPLE XII

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Water 25.0 Potassium xylene sulfonate (40%) 20.0 Sodium salt of a sulfated 3 mole ethylene oxide adduct of a C ₁₂ -C ₁₅ linear alcohol (60%) 23.33 Optical brighteners 0.8

Solution B was prepared from the following:

Grams Isopropanol 7.5 Optical brighteners 0.12 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 14.0 Ethylene glycol monoethyl ether 7.5

Solutions A and B were mixed together and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide 25.0 Water 62.45 Nitrilotriacetic acid 12.5 Perfume 0.3 Color 1.5

The cloud clear point of the above liquid detergent was between 180°F. and 190°F.

EXAMPLE XIII

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Water 25.0 Potassium xylene sulfonate 20.0 Potassium dodecyl benzene sulfonate 24.6 Optical brighteners 0.8

Solution B was prepared from the following:

Grams Isopropanol 7.5 Optical brighteners 0.12 Ethylene glycol monoethyl ether 7.5 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 14.0

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide 25.0 Water 61.18 Nitrilotriacetic acid 12.5 Perfume 0.3 Color 1.5

The cloud clear point of the above liquid detergent was between 110° and 111°F.

EXAMPLE XIV

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Water 25.0 Potassium xylene sulfonate (40%) 20.0 Potassium dodecyl benzene sulfonate (57%) 24.6 Optical brighteners 0.8

Solution B was prepared from the following:

Grams Isopropanol 7.5 Optical brighteners 0.12 Ethylene glycol monoethyl ether 7.5 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 14.0

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide 2.0 Water 76.68 Sodium nitrilotriacetate 20.0 Perfume 0.3 Color 1.5

The cloud clear point of the above liquid detergent was 103°F.

EXAMPLE XV

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Water 25.0 Potassium xylene sulfonate (40%) 20.0 Potassium dodecyl benzene sulfonate (50%) 28.0

Solution B was prepared from the following:

Grams Isopropanol 15.0 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 14.0

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Water 78.0 Sodium nitrilotriacetate 20.0

The cloud clear point of the above liquid detergent was 151°F.

EXAMPLE XVI

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Ethylene glycol monoethyl ether 5.0 Potassium dodecyl benzene sulfonate 28.0 Water 25.0

Solution B was prepared from the following:

Grams Isopropanol 15.0 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 14.0

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Water 93.0 Potassium nitrilotriacetate 20.0

This detergent composition separated into two phases; after the addition several grams of sodium toluene sulfonate, the liquid reverted to a single phase.

EXAMPLE XVII

A heavy-duty, clear liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Isopropanol 37.5 Optical brighteners 0.30 Potassium hydroxide (50%) 2.5

Solution B was prepared from the following:

Grams Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 65.0 Optical brighteners 2.0 Water 100.0

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Water 222.2 Potassium hydroxide (50%) 42.5 Nitrilotriacetic acid 23.5 Perfume 0.75 Color 3.75

The cloud clear point of the above liquid detergent was 122°F.

EXAMPLE XVIII

A heavy-duty, clear liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following:

Grams Isopropanol 12.5 Optical brighteners 0.30 Potassium hydroxide (50%) 2.5

Solution B was prepared from the following:

Grams Propylene glycol 25.0 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 65.0 Optical brighteners 2.0 Water 100.0

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Water 222.2 Potassium hydroxide (50%) 42.5 Nitrilotriacetic acid 23.5 Perfume 0.75 Color 3.75

The cloud clear point of the above liquid detergent composition was 129°F.

EXAMPLE XIX

A heavy-duty, clear liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following:

Grams Isopropanol 1000.0 Optical brighteners 24.0 Ethylene glycol monoethyl ether 2000.0 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 5200.0

Solution B was prepared from the following:

Grams Water 8000.0 Optical brighteners 160.0 Potassium hydroxide (50%) 100.0

Solution A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Water 17,920.0 Potassium hydroxide, 50% 3,400.0 Nitrilotriacetic acid 1,840.0 Perfume 60.0 Color 300.0

The cloud clear point of the above liquid detergent composition was 128°F. Four ounces, or 1/2 cup, is sufficient for the average washload.

EXAMPLE XX

A heavy-duty, clear liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following:

Grams Potassium xylene sulfonate 20.0 Potassium dodecyl benzene sulfonate 28.0 Water 25.0

Solution B was prepared from the following:

Grams Isopropanol 15.0 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 14.0

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Water 73.0 Nitrilotriacetic acid 20.0 Potassium silicate 5.0

EXAMPLE XXI

A heavy-duty, clear, liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following:

Grams Ethanol 2.0 Ethylene glycol monoethyl ether 5.0 Optical brighteners 0.46 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 7.00 Dodecyl dimethyl amine oxide 7.00

Solution B was prepared from the following:

Grams Optical brighteners 0.4 Ethanol 0.5 Water 34.90

Solution A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide (50%) 18.00 Nitrilotriacetic acid 9.00 Color 0.50 Perfume 0.15

The cloud clear point of the above liquid detergent was above 140°F.

EXAMPLE XXII

A heavy-duty, clear liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following:

Grams Ethanol 4.0 Optical brighteners 0.12 Ethylene glycol monoethyl ether 10.00 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 14.00 Dodecyl dimethyl amine oxide (31.7%) 45.00

Solution B was prepared from the following:

Grams Optical brighteners 0.80 Ethanol 1.00

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide (50%) 22.00 Nitrilotriacetic acid 12.50 Color 1.00 Perfume 0.30 Water 89.28

EXAMPLE XXIII

A heavy-duty, clear liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Optical brighteners 0.12 Ethanol 4.00 Ethylene glycol monoethyl ether 10.00 Sodium salt of sulfated 3 mole ethylene oxide adduct of a C ₁₂ -C ₁₅ linear alcohol (60%) 23.20 Alkyl (C ₁₂ -C ₁₄ ) dimethyl amine oxide (28.7%) 48.00

Solution B was prepared from the following:

Grams Ethanol 1.00 Optical brighteners 0.80

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide (50%) 23.00 Nitrilotriacetic acid 12.50 Color 1.00 Perfume 0.30

EXAMPLE XXIV

A heavy-duty, clear liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following ingredients:

Grams Optical brighteners 0.12 Ethanol 4.00 Ethylene glycol monoethyl ether 10.00 Sodium salt of sulfated 3 mole ethylene oxide adduct of a C ₁₂ -C ₁₅ linear alcohol (60%) 23.20 Alkyl (C ₁₂ -C ₁₄ ) dimethyl amine oxide (28.7%) 48.00

Solution B was prepared from the following:

Grams Ethanol 1.00 Optical brighteners 0.80

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide (50%) 32.00 Nitrilotriacetic acid 17.50 Color 1.00 Perfume 0.30 Water 62.08

The cloud clear point of the above liquid detergent was 106°F.

EXAMPLE XXV

A heavy-duty, clear liquid detergent was prepared at room temperature as follows:

Solution A was prepared by mixing together the following:

Grams Optical brighteners 0.06 Ethanol 2.00 Ethylene glycol monoethyl ether 5.00 Linear C ₁₄ -C ₁₅ alcohol ethoxylated with 11 moles of ethylene oxide 25.00

Solution B was prepared from the following:

Grams Optical brighteners 0.5 Ethanol 0.5 Water 55.9 Potassium hydroxide (50%) 0.5

Solutions A and B were combined and the mixture was added slowly with stirring to the following mixture:

Grams Potassium hydroxide (50%) 6.50 Nitrilotriacetic acid 3.23 Color 0.75 Perfume 0.15

The cloud clear point of the above liquid detergent was 125°F.

While the detergent compositions of the present invention are excellent compositions for all types of cleaning operations, they are extremely effective for the cleaning of textiles in a conventional laundry or washing machine. Thus, the detergent compositions of the present invention can be effectively used for laundering fabrics in water having a temperature of from about 60°F. to about 212°F., the detergent composition of the present invention exhibiting unusually effective detergency characteristics in both cold and hot water. Preferably, the washing step of the invention is followed by rinsing and drying of the fabric. The detergent composition concentration in the wash solution should range from about 0.05 percent to about 0.5 percent by total weight.

In washing fabrics, the addition of the fabrics and the detergent composition can be conducted in any suitable conventional manner. Thus, for example, the fabrics can be added to the container or washer either before or after the washing solution is added. The fabrics are then agitated in the detergent solution for varied periods of time, a wash cycle of from 8 to 15 minutes being generally used in the washing cycle of an automatic agitator type washer. As stated above, following the washing of the fabrics, the detergent solution is drained off and the fabrics are rinsed in substantially pure water. Here again, as a matter of choice, the fabrics can be rinsed as many times as desired. After the fabrics are rinsed, they are dried, first by spinning, and then by contact with the air as in a conventional hanging of the fabrics on a clothesline or in an automatic dryer type system.