Detergent Compositions

Abstract

A liquid detergent system having a controllable viscosity and clarity, including a water-soluble paraffin sulfonate and a water-soluble, higher alkane, ether sulfate. Control of the viscosity and clarity is accomplished by using a control system comprising a lower aliphatic alcohol and urea.

Description

The present invention relates to clear, stable, liquid detergent compositions containing:

A. Water soluble salts of paraffin sulfonates,

B. Compatible water soluble salts of higher alkyl ether sulfates in a ratio of A:B of about 10:1 to 1:1, and

C. a viscosity and clarity control system.

Preferably, the compositions are prepared in the form of a clear, stable liquid detergent composition containing A and B in a total content of about 10 to about 60 percent by weight in an aqueous medium.

Liquid detergent compositions are known which comprise sodium dodecyl benzene sulfonate and ammonium alkyl ether sulfate. In order to formulate liquid detergents comprising these two ingredients in sufficient concentration to be practical, it has been necessary to include in the composition relatively high proportions of solubilizing agents or hydrotropes such as the lower aliphatic alcohols (e.g., ethyl alcohol), urea, low molecular weight alkylbenzene sulfonates (e.g., sodium xylene sulfonate), and the like.

It has now been discovered that commercially acceptable liquid detergent compositions can be formulated based on:

A. water soluble salts of paraffin sulfonates,

B. compatible water soluble salts of alkyl ether sulfates, as hereinafter defined, with as high as 60 percent active ingredients in an aqueous liquid provided the ratio of A:B is from 10:1 to 1:1, and

C. a viscosity and clarity control system, as hereafter defined.

The liquid detergent compositions of the present invention have significant advantages over the previously known liquid detergents based on alkyl aryl sulfonates and alkyl ether sulfates.

Among the advantages of the present invention over the previously known liquid detergents are the following:

1. Liquid detergent compositions of substantially equal percentage of active ingredients and comparable clarity can be produced in accordance with the present invention with significantly lower percentages of hydrotropes than were necessarily used in the previously known compositions.

2. The compositions of the present invention produce better foam than the prior art compositions both in quantity and durability.

3. Compositions of the present invention, when diluted to the same concentration for use as the prior art compositions give substantially higher performance, particularly in dish washing.

4. Washing compositions made with the product of the present invention also have significantly lower surface tension than compositions of the same concentration using prior art compositions.

Among the advantages of the present invention are improved and controlled performance such as foaming and dish washing ability, viscosity and clarity which are important features in consumer acceptability.

The paraffin sulfonates used in the present invention are usually mixed secondary alkyl sulfonates having from ten to twenty carbon atoms per molecule, preferably they will have at least 80 percent, usually at least 90 percent, of from 10-17 carbon atoms per molecule. Where the major proportion has 14-15 carbon atoms per molecule, optimum foaming performance appears to be obtained at varying concentrations and water hardnesses. These sulfonates are preferably prepared by subjecting a cut of paraffin, corresponding to the chain lengths specified above, to the action of sulfur dioxide and oxygen in accordance with the well known sulfoxidation process. The product of this reaction is a secondary sulfonic acid which is then neutralized with a suitable base to provide the water soluble secondary alkyl sulfonate for use in the present invention. Similar useful secondary alkyl sulfonates may be obtained by other methods, e.g., by the sulfochlorination method in which chlorine and sulfur dioxide are reacted with paraffins in the presence of actinic light, the resulting sulforyl chlorides being hydrolyzed and neutralized to form the secondary alkyl sulfonates.

The higher alkyl ether sulfates used in the present invention are represented by the formula:

RO(C.sub.2 H.sub.4 O).sub.n SO.sub.3 X

in which R is a primary or secondary alkyl group that may be straight or branched having from 10 to 18 carbon atoms, preferably 12 to 14, X is a suitable cation, as hereinafter defined, and n is a number from 1 to 10, preferably 3 to 6. These detergents are produced by sulfating the corresponding ether alcohol and then neutralizing the resulting sulfuric acid ester thereof.

The cation of the paraffin sulfonate and alkyl ether sulfate may be an alkali metal, an alkaline earth metal (e.g., magnesium), ammonium or lower amine (including alkylolamines). It is preferred to use the sodium salt of the paraffin sulfonic acid and an ammonium salt of the alkyl ether sulfuric acid ester.

It is advantageous to include non-ionic surface active agents in the composition to improve the quantity and the lasting quality of the foam. Among the non-ionic surface active agents which may be used satisfactorily are higher alcohols, ether alcohols, ethoxylated phenols, and higher fatty acid amides.

It is preferred that the liquid detergent composition contain a higher fatty acid alkylolamide material in sufficient amount to act as a suds builder. Its presence results in a product which exhibits high foaming power in use, particularly in the stability of the foam generated during dish washing or laundering operations. It should not be employed in an amount sufficient to destroy the desired physical properties. The acyl radical of the alkylolamide is selected from the class of fatty acids having 8 to 18 carbon atoms and each alkylol group usually has up to 3 carbon atoms. It is preferred to use the monoethanolamides of lauric and myristic acids but diethanolamides and isopropanolamides as well as monoethanolamides of fatty acids having about 10 to 14 carbon atoms in the acyl radical are satisfactory. Examples are capric,lauric, myristic and coconut monoethanolamides, diethanolamides and isopropanolamides and mixtures thereof. There may be employed also the alkylolamides which are substituted by additional alkylol groups, suitable examples may be the above amides condensed with 1 or 2 moles of ethylene oxide.

While any suitable ratio of paraffin sulfonates to alkyl ether sulfates may be used as described, it has been found that the ratio should be at least about 60 - 40 for an optimum combination of properties, particularly in the presence of amide or the like. Suitable ratios are 60:40, 70:30, 80:20 and 85:15 by weight with 0-8 percent alkylolamide, preferably 1-6 percent and usually 4-6 percent, such as coconut monoethanolamide, diethanolamide, or ethanolamide condensed with about 1-4 moles of ethylene oxide. It is understood that the sulfonate and sulfate salts may be in any suitable water-soluble salt form such as the sodium, potassium, ammonium, and mono-, di- and tri-ethanolamine salts, or mixtures thereof.

The higher alcohols and ether alcohols which may be used as foam builders in the present invention are represented by the formula:

RO(C.sub.2 H.sub.4 O).sub.n H

exemplifications of which include decoxytriethoxyethanol, lauroxytetraethoxyethanol, tetradecoxypentaethoxyethanol, hexadecoxynonaethoxyethanol and octadecoxyheptaethoxyethanol among the general class illustrated, and referring to the formula in which R represents an alkyl group that may be straight or branched having from 10 to 18 carbon atoms and n is a number from 0 to 10, preferably 3 to 6. In the case of higher ether alcohols, the preferred chain length for the alkyl group is from C.sub.10 - C.sub.14 when n has a value from 3-6 as preferred.

When used, the non-ionics may be present in the formula up to about 10 percent by weight of the product, preferably up to about 4 percent of the alcohol ether and up to about 8 percent of the fatty acid alkylolamide.

The viscosity and clarity control system used in the liquid detergent composition of the invention comprises urea, a lower aliphatic alcohol, and optionally a water-soluble hydrotropic substance which is effective in promoting the compatibility of the ingredients in the liquid product and can be substituted for part of the urea or alcohol.

Suitable hydrotropic substances are the alkali metal organic sulfonated (including sulfated) salts having a lower alkyl group up to about 6 carbon atoms. The preferred sulfonated hydrotropes are alkyl aryl sulfonates having up to 3 carbon atoms in the lower alkyl group, e.g., the sodium and potassium xylene, toluene, ethylbenzene and isopropyl benzene (cumene) sulfonates. Sulfonates made from xylene include orthoxylene sulfonate, metaxylene sulfonate, paraxylene sulfonate and ethylbenzene sulfonate. Commercial xylene sulfonates usually contain metaxylene sulfonate as the main ingredient. Analysis of typical commercial xylene sulfonate products shows about 40- 50 percent metaxylene sulfonate, 10-35 percent orthoxylene sulfonate and 15-30 percent paraxylene sulfonate with 0-20 percent ethylbenzene sulfonate. Any suitable isomeric mixture, however, may be employed. Sodium cumene sulfonate and sodium xylene sulfonate are preferred lower alkyl aryl sulfonates to use in the compositions of the present invention. It is also permissible to use suitably lower alkyl sulfate salts having about 5 to 6 carbon atoms in the alkyl group such as alkali metal n-amyl and n-hexyl sulfates.

The use of the viscosity and clarity control system imparts superior low temperature clarity of the liquid detergent composition and provides control of the viscosity of the product over a wider range for any particular concentration of active ingredients, as will be set forth in greater detail hereinafter.

The lower aliphatic alcohols preferably have two or three carbon atoms. Thus, ethyl alcohol, propyl alcohol, isopropyl alcohol or propylene glycol can be used, preferably, ethyl alcohol will be used.

The exact proportions of urea, lower alcohol, and hydrotropic substance best suited for any particular composition may be determined by the formulator by conventional tests. The weight content of this viscosity and control system based upon the total composition will vary from 2.5-15 percent and preferably from 6 to 13 percent. Within that range, the urea and the alcohol will vary within the ranges of 0.5 to 5.0 percent, preferably 1 to 4 percent and 2 to 10 percent, preferably 5 to 8 percent, respectively. It is desirable to maintain the ratio of urea to alcohol within the range of 1:1.5 to 1:3 parts by weight, most preferably, at about 1:2.5 when using an active ingredient content above about 30 percent by weight, preferably 35- 45 percent including alkylolamide or the like. Varying amounts of hydrotrope such as xylene sulfonate or the like may be added or substituted in part for the alcohol or urea so as to form a ternary system with special properties such as to markedly increase the viscosity to greater levels. The amount should be selected by formulation so as to maintain a satisfactory viscosity and cloud point and maintain other desirable properties. Generally, the hydrotrope may constitute up to about 50 percent by weight of the total viscosity and control system.

The liquid detergents of the present invention may also contain any of the additives heretofore used in other liquid detergent compositions such as sequestrants, e.g., salts of ethylenediamine tetraacetic acid, such as the sodium and potassium salts, and salts of hydroxy ethyl ethylene diamine triacetate. It is desirable in some cases to tint or color the liquid detergent composition and any suitable dyes may be used for this purpose. Perfume may also be added to these compositions to give them a pleasant odor.

Water is used as the liquid vehicle for the liquid detergent compositions of the present invention. It will vary in proportion from about 50 to 90 percent, depending upon the content of the other ingredients of the composition.

In order to illustrate some of the benefits of the present invention, two compositions containing sulfonated hydrotropes and alcohol are compared with two conventional type liquid detergent compositions based on sodium dodecyl benzene sulfonate. Table 1 sets forth the four compositions. Sodium paraffin sulfonate is used in Examples 1 and 2 at the same level of concentration as the sodium dodecyl benzene sulfonate is used in Examples 1A and 2A respectively. Ammonium alkyl ether sulfate is also present at the same levels in each Example of pair 1 and 1A and of pair 2 and 2A. The non-ionic detergent (alcohol ether in Examples 1 and 1A and lauric myristic monoethanol amide in Examples 2 and 2A) is also at the same level in the two Examples of each pair. The sodium xylene sulfonate and alcohol content is adjusted to give the same physical properties to each Example of pair 1 and 1A and of pair 2 and 2A, respectively. The import of Table 1 is that satisfactory formulas having properties quite comparable from the physical standpoint with prior art formulas are obtainable in accordance with the present invention with a significantly reduced percentage of alcohol and sodium xylene sulfonate. ##SPC1##

Referring to Table I, it will be noted in Example 1 that the same physical properties were obtained with 6 percent ethyl alcohol that required 8.5 percent for Example 1A. Example 2 had the same physical properties with 4 percent sodium xylene sulfonate and 5.5 percent alcohol that Example 2A possessed at 6 percent sodium xylene sulfon-ate and 7 percent alcohol.

Table II compares the results of two different performance tests on washing solutions made from Examples 1 and 2 and rom Examples 1A and 2A. One of the performance tests is a dishwashing test which was carried out at two different levels of water hardness, viz., at 50 and 300 parts per million (PPM) of hardness, and at two concentrations of detergent, viz., 0.075 percent and 0.15 percent for each level of water hardness. The other test is a test of foam height at 300 parts per million water hardness at 0.05 percent level of concentration of detergent.

The dishwashing tests mentioned above and hereinafter were carried out by uniformly soiling standard plates with a soil which consists of a commercial hydrogenated fatty (cottonseed) oil by spreading a small amount, equally, on each plate.

The plates are washed in dishpans which contain 6 liters of wash water at 43.degree.C. Each of the compositions to be tested (at the two different concentrations of the liquid detergent, and at the two different water hardnesses) is prepared and placed, separately, in different dishpans. The plates are then washed in the dishpans to an endpoint of a permanent break in the foam covering the dishpan; the number of plates which can be washed to that end point is noted and recorded. A difference of 2 plates in the results obtained is generally considered necessary in order to be significant at a 95 percent confidence level.

The second test also mentioned above and which is employed to ascertain the foam characteristics of the compositions is the foam height test, and specifically, the well known Ross & Miles Test (Pour Foam Test). This test consists essentially of measuring foam in a measuring cylinder. A jacketed measuring cylinder is employed into which a portion of the solution (at 0.05 percent in 300 ppm water) to be tested is placed. The foam is formed by allowing a second portion of the solution to stream in from a fixed height through a standard orifice. The foam is recorded as the maximum reached in the measuring cylinder. ##SPC2##

It will be noted that Examples 1 and 2 are significantly better under all test conditions than Examples 1A and 2A.

The foregoing results are typical of the improved performance which can be obtained in accordance with the present invention as compared with compositions of the prior art.

Table III shows the improvement in surface tension of compositions of the present invention compared with the prior art. ##SPC3##

The number of drops is that delivered by a stactometer (or stalagmometer) from a given volume of the detergent solution at the considered concentration and water hardness. The surface tension is inversely proportional to this number of drops. Thus, the higher is the number of drops, the lower is the surface tension, and the better the detergent.

Table IV gives the general ranges of the principal ingredients within which the preferred compositions of the invention are formulated.

TABLE IV

The preferred ranges are as follows:

% Paraffin sulfonates 15-40 Alcohol ether sulfates 4-15 Alkylolamide or alkylolamide - Eto condensate 0- 8 Urea 1- 4 Ethanol 5- 8 Water QS

the following examples further describe the invention, with all amounts being by weight:

EXAMPLE 3

% Sodium paraffin sulfonate 30 C.sub.12 -C.sub.15 Fatty alcohol EO : 1 NH.sub.4 sulfate 8 Coconut fatty acid monoethanolamide 2 Urea 2 Ethyl alcohol 5.4 Sodium ethylene diamine tetraacetate 0.075 Water (with small amounts of color, preservative and perfume) QS Total 100

The above product exhibits satisfactory foaming and dishwashing properties combined with preferred physical properties such as a cloud point of about 5.degree.C. and a viscosity of about 170 cps. at 25.degree.C. using a Brookfield Viscosimeter Model LVF Spindle 1 at 30 RPM. The paraffin sulfonate employed has the following approximate composition : 5% C.sub.13, 16% C.sub.14, 30% C.sub.15, 30% C.sub.16, 15% C.sub.17 and 4% C.sub.18, with an average molecular weight of about 328. Various impurities may be present in commercial products such as small amounts of free paraffin or disulfonates.

EXAMPLE 4

A liquid detergent having similar properties as that of Example 3 is prepared by substituting an equivalent amount of coconut monoethanolamide condensed with about 2 moles of ethylene oxide for the monoethanolamide.

EXAMPLE 5

A satisfactory liquid detergent is prepared using the same materials as Example 3 in the following proportions : 22 percent paraffin sulfonate, 13 percent alkyl ether sulfate, 5 percent lauric myristic monoethanolamide, 5 percent urea and 6 percent ethanol with the balance being essentially water.

EXAMPLE 6

A satisfactory liquid detergent is prepared with the same formula as Example 3 except that it contains 5.6 percent ethanol, 0.6 percent sodium xylene sulfonate and 1.8 percent urea.

One of the advantages of the urea-lower alcohol control system is that a change in the physical characteristics of the composition is possible by varying the ratio of alcohol to urea. In the specific composition of Example 3, the ratio of alcohol to urea is 5.4 to 2 (2.7:1) which resulted in the clear point below 7.degree.C. and the viscosity of 170. By changing the alcohol: urea ratio by increasing the alcohol content, it is possible to decrease the viscosity and raise the clear point whereas by decreasing the alcohol content the clear point can be lowered and the viscosity increased. Hydrotropes such as sodium xylene sulfonate tend to have an effect similar to that of the alcohol, ie., increases thereof will raise the clear point but lower the viscosity. It is important to balance these constituents of the control system within the cited ranges to obtain the desired results. For optimum balance of clear point and viscosity, the total content of the control system will vary with the content of the active ingredients (paraffin sulfonate, alcohol ether sulfate and non-ionic detergents).

The clear point is also influenced by the amount of esters in the amide and sodium sulfate in the paraffin sulfonate and alkyl ether sulfate used as raw materials in preparing the compositions and, for compositions having a low clear point, raw materials with low content of these impurities should be used. The characteristics given above for the specific composition of Example 3 can best be obtained if the amide does not contain over 2 percent esters and the paraffin sulfonate does not contain over 4 percent sodium sulfate.

Although the present invention has been described and illustrated with reference to certain specific compositions, these are to be considered as illustrative of and not as limitations on the present invention. All proportions are given hereinabove in percentages by weight of the entire composition unless otherwise indicated.

Claims

What is claimed is:

1. A clear, stable liquid detergent consisting essentially of a water-soluble paraffin sulfonate salt having from 10 to 20 carbon atoms in the molecule, a compatible water-soluble higher alkyl ether sulfate salt in a ratio of paraffin sulfonate to ether sulfate of about 10:1 to 1:1; and means for controlling the viscosity and clarity of said liquid detergent; wherein the total content of said paraffin sulfonate and alkyl ether sulfate salts is about 10 percent to about 60 percent by weight in an aqueous medium, the means for controlling the viscosity and clarity constitutes from about 6 to 13 percent by weight of the liquid detergent composition and comprises a mixture of urea and a lower alkanol in a ratio of 1:1.5 to 1:3; said alkyl ether sulfate being represented by the formula:

RO(C.sub.2 H.sub.4 O).sub.n SO.sub.3 X

in which R is an alkyl group having 10 to 18 carbon atoms per molecule, n is a number from 1 to 10, and X is a cation; and the cation of the sulfonate and said sulfate being selected from the group consisting of alkali metals, alkaline earth metals, ammonium, and lower amines.

2. A detergent as set forth in claim 1 in which said paraffin sulfonate is a mixture of compounds having about 13 to 18 carbon atoms per molecule.

3. A detergent as set forth in claim 1 in which R is an alkyl group having between 12 and 14 carbon atoms per molecule and n is a number from 3 to 6.

4. A detergent as set forth in claim 1 which also contains a nonionic foam builder selected from the group consisting of compounds represented by the formula:

RO(C.sub.2 H.sub.4 O).sub.n H

in which R is an alkyl group having 10 to 18 carbon atoms and n is a number from 0 to 10, and mono- and diethanolamides and isopropanolamides of a C.sub.10 -C.sub.14 fatty acid, said foam builder being present in amounts up to about 10 percent by weight of the liquid detergent.

5. A detergent as set forth in claim 4 in which R is an alkyl group having 10 to 18 carbon atoms, n in the formula for said nonionic foam builder is a number from 3 to 6.

6. A detergent as set forth in claim 4 in which said nonionic foam builder is lauric-myristic monoethanol-amide.

7. A detergent as set forth in claim 1 which contains 20 to 35 percent by weight of sodium C.sub.13 -C.sub.18 paraffin sulfonate; 6 to 15 percent by weight of ammonium C.sub.12 -C.sub.15 alkyl triethenoxy ether sulfate; 0 to 6 percent by weight of lauric myristic monoethanolamide; a viscosity and clarity control agent comprising 0.5 to 5 percent by weight of urea and 2 to 10 percent by weight of lower alkanol; and water.

8. A detergent as set forth in claim 7 in which said alkanol is ethyl alcohol.

9. A detergent as set forth in claim 7 in which said means for controlling the viscosity and clarity further includes a lower alkyl benzene sulfonate hydrotrope.