Detergent composition

Patented Jan. 17, 1950

2,494,580

UNITED STATES PATENT OFFICE

2,494,580

DETERGENT COMPOSITION

Walter C. Preston, Cincinnati, Ohio, assignor to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio

No Drawing. Application May 24,1947, Serial No. 750,369

Claims.

The present invention relates to detergent compositions, and more particularly to soapcontaining compositions which are highly resistant to curd-forming ingredients of hard water.

It is well known that the use of ordinary toilet or household soap in hard water results in the formation and precipitation of insoluble fatty acid salts, more commonly referred to as “lime soaps.” It is also known that such precipitated lime soaps have a tendency to coagulate and form a sticky curd. This curd is commonly observed in the wash stand and bath tub and also in the laundry rinse tub where it rises to the surface of the water as a scum, adheres to the walls of the tub as a ring, and sticks to the clothes during the rinsing operation, thereby giving to the clothes an unsightly dingy appearance, producing spots upon subsequent ironing, and often causing the development of a rancid odor. When soap is used for shampooing the hair, rinsing with hard water results in deposition of the lime soaps on the hair. In applications as divergent as the dyeing of textile fabrics and the plating of metals, the formation of lime soaps has undesirable effects.

In fact, if soap is used in hard water, insoluble lime soap curd forms during the rinsing process or whenever the soap dilution becomes sufficiently great to destroy the foaming and dispersing power of the soap.

The coagulation of the lime soaps to form soap curd is dependent not only on the degree of dilution of the soap in the hard water, but also on the age of the solution and on the degree of violence of agitation to which it is subjected, increasing age and increasing agitation both being important factors in promoting coagulation.

The primary object of the present invention is to provide a soap composition which forms little or no lime soap curd when used with hard water.

Another object is to provide a detergent composition which will not form a sticky lime soap curd which will cling to clothes or form the unsightly, difficultly removable soap ring in the washstand or bathtub.

A further object is to increase the resistance of soap-containing detergent compositions to precipitation of lime soap and the coagulation thereof to form curd when such compositions are used in hard water under conditions involving prolonged standing or agitation.

It is known that synthetic detergents such as various organic sulfonates and sulfates, when (Cl. 252—121) mixed or used with soap in hard water are capable of reducing the formation of lime soap curd. Several such mixtures have been proposed. Some have been commercially produced and designated as “hard water soaps,” allegedly free of curd forming characteristics when used in hard water. However, according to my investigations and experience, products prepared in accordance with prior art practices, even those which contain more synthetic detergent than soap, frequently form objectionable curd in hard water under normal conditions of use. As the proportion of synthetic detergent increases, the trouble with such hard-water curd may decrease in seriousness, but at the same time the cost of the product increases and some of the desirable physical properties found in soap are adversely affected.

As more fully hereinafter described, I have discovered that esters of allyl alcohol and soapforming carboxylic acids (although possessing no power to inhibit curd formation when used with soap alone) have a marked power to inhibit lime soap precipitation and curd formation in the case of curd-forming detergent compositions comprising essentially a mixture of soap and synthetic detergent in proportions more fully hereinafter described. This power exists even when the compositions are used under conditions wherein the solution is subjected to prolonged standing or to mild or vigorous agitation.

I am aware that prior workers in the art have suggested the combination of soap with synthetic detergents (Patents 1,906,484, 2,026,816 and 2,088,308). None of these patents, however, suggests the use of allyl esters of higher carboxylic acids for inhibiting the curd formation when compositions comprising soap and synthetic detergent are employed in hard water.

Allyl esters which come within the scope of the invention are those esters of allyl alcohol and saturated or unsaturated aliphatic soap-forming carboxylic acids having from 8 to 25 carbon atoms in the molecule. Of especial interest are 45 the allyl esters of saturated fatty acids having from 10 to 14 carbon atoms.

Some specific esters which may be used in the practice of the invention are: allyl caprate, allyl laurate, allyl myristate, allyl palmitate, allyl 50 stearate, and allyl oleate.

Instead of employing esters of single fatty acids as above indicated, corresponding esters of mix' tures of fatty acids, especially those mixtures obtainable from oils, fats, and waxes of animal and ·· vegetable origin, may be employed without de10

2,494,580 parting from the spirit of the invention. For example, those esters of a mixture of fatty acids derived from oils of the coconut oil group (a group of tropical nuts oils characterized by their high content of lauric and myristic acids) such as .·, coconut oil, palm kernel oil, and babassu oil are of particular value, but those esters of mixtures of fatty acids derived from other oils and fats such as palm oil, tallow, cottonseed oil, sunflower seed oil, fish oils such as menhaden oil and in the like, as well as hydrogenated and partially hydrogenated fats and oils in .general, may also be employed. In addition, allyl esters of higher aliphatic carboxylic acid mixtures having from about 10 to about 25 carbon atoms and derived i.-, by oxidation of paraffin hydrocarbons of petroleum or obtained by hydrogenation of carbon monoxide (commonly known as the FischerTropsch process) or indirectly by oxidation of the saturated or unsaturated hydrocarbons or oxygenated hydrocarbons resulting from this this process are. suitable in the practice of my invention.

The kind of soap which is used in preparing my improved detergent compositions is not limita- 25 tion of the invention. Any of the water-soluble soaps formulated for industrial, household and toilet use may be employed. Thus the character of the soap constituent may vary widely in its composition depending on whether the final 30 ternary composition is to be in powdered, spray dried, flake, bar, paste, thread, liquid or other form, and it is to be understood that the specific soaps referred to in the example given below and prepared from tallow and coconut oils and are 35 not to be construed as limiting in nature. Water-soluble soaps such as the sodium soaps and other suitable alkali metal or ammonium soaps derived from other fats and oils such as cottonseed oil, soybean oil, corn oil, olive oil, palm oil, 40 peanut oil, palm kernel oil, lard, greases, fish oils and the like as well as their hydrogenated derivatives, and mixtures thereof, properly blended to yield the desired soap quality, may be used in compounding the ternary mixtures herein con- ₄₅templated.

The synthetic detergent constituent of the present detergent compositions may be broadly designated as a detergent of the class consisting of water-soluble salts of organic sulfonic acids 50 and water-soluble salts of aliphatic sulfuric acid esters, that is, water-soluble salts of organic sulfuric reaction products having in the molecular structure a radical selected from the group consisting of sulfonic acid and sulfuric acid ester 55 radicals. As indicated above in the designation of the soaps which may be used in compounding the compositions of my invention, the choice of synthetic detergent will depend inter alia on the physical characteristics of the final product, that is, 60 whether the composition is to be in fiake, bar, paste, or other form. Obviously if a detergent composition in bar form is desired, it will be impractical to combine ingredients which are too soft to retain their shaped form in use. >5

Synthetic detergents of special interest and particular value are the water-soluble salts of higher alkyl sulfuric acids containing from 8 to 18 carbon atoms in the alkyl radical. More specifically, the alkali metal salts of sulfuric acid ,0 esters of normal primary aliphatic alcohols having 10 to 18 carbon atoms, particularly those whose principal active ingredients is a watersoluble salt of lauryl sulfuric acid or oleyl sulfuric acid, have proved of value in compounding 75 products of the present invention. Thus the sodium salt of alkyl sulfuric acids obtained from the mixed higher alcohols derived by the reduction of coconut oil, palm kernel oil, babassu oil, or other oils of the coconut oil group or the sodium alkyl sulfate derived from sperm oil alcohols may be employed. In addit'nn, water-soluble alkyl sulfates having pronounced detergent power and derived from high molecular branched chain primary alcohols or from high molecular secondary alcohols may be used.

Other aliphatic sulfuric acid esters which may be employed in the preparation of detergent compositions of the present invention include watersoluble salts of sulfuric acid esters of polyhydric alcohols incompletely esterfied with high molecular weight soap-forming carboxylic acids. Such synthetic detergents include the watersoluble salts sulfuric acid esters of higher molecular weight fatty acid monoglycerides such as sodium salt of the coconut oil fatty acid monoester of 1, 2-dihydroxy-propane-3-sulfuric acid ester, triethanolamine salt of monooleoyl diethylene glycol sulfate, sodium mono-myristoyl ethylene glycol sulfate, and sodium mono-lauroyl diglycerol sulfate.

Similarly water-soluble salts of ethers of high molecular weight normal primary alcohols and lower molecular weight hydroxy alkyl sulfuric acid esters may be employed. Specific examples of such synthetic detergents are 'sodium salt of mono fatty-alcohol-of-coconut-oil ether of glycerol monosulfuric acid and sodium salt of lauryl ether of ethylene glycol monosulfuric acid.

In addition, sulfuric acid ester synthetic detergents such as water-soluble salts of sulfated higher fatty acid alkanolamides, for example the sodium salt of sulfated coconut oil fatty acid ethanolamide and of sulfated babassu oil fatty acid glycerol amide, may be employed in the practice of the invention.

The allyl esters hereinabove referred to are active also in inhibiting curd formation in the case of those detergent compositions which contain in combination with soap an organic synthetic detergent having a true sulfonate group. These synthetic detergents include salts of higher molecular weight monofatty acid esters of lower molecular weight hydroxy alkyl sulfonic acids such as the sodium salt of the coconut oil fatty acid monoester of l,2-dihydroxy-propane-3-sulfonic acid, and the oleic acid ester of the sodium salt of isethionic acid. Included also are the higher molecular weight fatty acid amides¹ of lower molecular weight amino alkyl sulfonic acids (for example, sodium and potassium salts of oleic acid amide of N-methyl taurine), the watersoluble salts of the higher molecular weight alcohol esters of sulfocarboxylic acids (for example, sodium salt of the lauryl alcohol ester of sulfoacetic acid), lower molecular weight sulfocarboxylic acid amides of alkylolamine esters of higher molecular weight fatty acids (for example, sodium salt of the sulfoacetamide of amino ethyl laurate), higher alkylated aryl sulfonic acids (for example, sodium and potassium salts of the sulfonic acid derived from the condensation product of benzene and a chlorinated kerosene fraction containing predominantly 10 to 14 carbon atoms per molecule such as represented by the formula ____ SO,H where R is the alkyl group), and ethers of higher

3,494,880 molecular weight hydroxy alkyl sulfonic acids (for example, monolauryl ether of 1,2-dihydroxypropane-3-sodium sulfonate and monolauryl ether of the sodium salt of isethionic acid).

Although the essential Ingredients of the compositions of the present invention comprise essentially a ternary mixture of an allyl alcohol ester of a higher fatty acid, soap and synthetic detergent, it will be appreciated that the incorporation in the mixture of additional ingredients commonly used with cleansing compositions, such as perfumes, starch, urea, triethanolamine, inorganic salts (sulfates, silicates, carbonates, ortho-, meta-, pyro-, and triphosphates and the like), albuminous substances, glycerin, insecticides and germicides and the like, is contemplated as part of the instant invention.

The following examples will illustrate the manner in which the invention may be practiced, but it is to be understood that such details are given merely for exemplification purposes and are not to be construed as limiting the scope of the appended claims. In all instances the proportions are expressed in parts by weight.

Example 1.—A. mixture was prepared consisting of 70 parts of sodium soap from 80% tallow and 20% coconut oil and containing about 15% water, 25 parts of the. sodium salt of the coconut oil fatty acid mono-ester of 1,2-dihydroxypropane-3-sulfonic acid (commonly known as coconut oil monoglyceride sulfonate), and 5 parts of allyl laurate. The ratio of soap to synthetic in this mixture was about 2.4:1, and the ratio of synthetic to allyl laurate was 5:1. A 0.04% solution of this mixture in 20 grain water was shaken vigorously, but no hard-water soap curd was formed. At the same time and when tested in the same manner, mixtures containing either (a) 70 parts of the same soap and 30 parts of the same synthetic detergent, or (b) 75 parts of the same soap and 25 parts of the same synthetic detergent gave hard-water soap curd. This showed that substituting 5 parts of allyl laurate for 5 parts of either the soap or the synthetic detergent in such a mixture of the two promotes the power of the synthetic detergent to inhibit curd formation. In admixture with soap alone, allyl laurate had no curd-inhibiting power.

Example 2.—In the manner described in Example 1 and using the same materials therein used, the following three mixtures were compared, with the results shown in the table below.

[Concentration, 0.04%; water hardness, 20 grains per gallon]

<td></td><td> (a)</td><td> ¢)</td><td> (C)</td>

<td> Partsofsoap¹_____ __ ___________- ...</td><td> 70</td><td> 70</td><td> 80</td>

<td> Parts of synthetic detergent_______________</td><td> 30</td><td> 20</td><td> 20</td>

<td> Parts of allyl laurate________________________</td><td> 0</td><td> 10</td><td> 0</td>

<td> Ratio, Soap: Synthetic_____________________</td><td> 2:1</td><td> 3:1</td><td> 3.4:1</td>

<td> Ratio’ Synthetio: Allyl laurate</td><td></td><td> 2a</td><td></td>

<td> Result of shaking____1______________________</td><td> curd</td><td> no curd</td><td> curd</td>

¹ This soap contained about 15% water.

This shows that substituting 10 parts of allyl laurate for 10 parts of either the soap or the coconut oil monoglyceride sulfonate in such a mixture of the two promotes the power of the monoglyceride sulfonate to inhibit curd formation. In admixture with soap alone, allyl laurate had no curd-inhibiting power;

Example 3.—Milled bars which lather and cleanse satisfactorily and do not form objectionable curd when used in 20 grain water are made by milling on soap milling rolls a mixture consisting of 50 parts of the soap described in Example

1, 40 parts of a commercial synthetic detergent containing about 88% sodium salt of the sulfuric acid ester of alcohols derived from coconut oil (the remaining 12% being largely NaaSOt), and 10 parts of allyl laurate, to which mixture about 4 parts of water are added as needed to give and maintain the proper working consistency during milling and subsequent plodding. The resulting milled ribbons are then plodded in customary soap-making equipment, and the plodded product is cut and stamped in the form of bars. The ratio of soap to synthetic detergent in these bars is about 1.2:1, and the ratio of synthetic detergent to allyl laurate is about 3.5:1.

Example 4.—Milled bars are made by the procedure of Example 3, using 65 parts of the soap therein used, 25 parts of the sodium salt of babassu fatty acid mono-ester of 1,2-dihydroxy-propane-3-sulfonic acid, and 10 parts of allyl esters of babassu oil fatty acids. These bars lather and cleanse well and do not give objectionable curd in 20 grain water. The ratio of soap to synthetic in these bars is about 2.2:1, and the ratio of synthetic to allyl ester is about 2.5:1.

Example 5.—Milled bars are made by the procedure of Example 4, using 51.8 parts of the soap therein used, 48 parts of the synthetic detergent used therein, and 8 parts of the allyl esters of mixed babassu fatty acids. These bars lather and clean well and do not give objectionable curd in 20 grain water. The ratio of soap to synthetic in these bars is about 0.9:1, and the ratio of synthetic to allyl ester is about 6:1.

Example 6.—Detergent flakes which suds and cleanse satisfactorily and do not give objectionable curd in 20 grain water are made by milling on soap-milling rolls a mixture consisting of 74 parts of sodium soap from 75% tallow and 25% coconut oil and containing about 3% water, 30.3 parts of a dried neutralized reaction product of oleum with coconut fatty acid esters of allyl alcohol consisting of about 66% coconut monoglyceride sulfonate, about 7.3% sodium soap of coconut oil fatty acids, and about 26.7% Na2SO4, and 6 parts of the coconut fatty acid esters of allyl alcohol, to which mixture a little water is added as required to give plasticity to the resulting milled ribbons. The milled ribbons are converted into flake form in known manner. The ratio of soap to synthetic detergent in these flakes is about 3.7:1, and the the ratio of synthetic detergent to allyl ester is about 3.3:1.

Example 7.—Detergent flakes are prepared by the procedure of Example 6, using 51.6 parts of sodium soap from tallow containing about 3% water, 70 parts of a commercial alkyl aryl sulfonate detergent containing about 40% alkyl benzene sulfonate sodium salt and about 60% NaaSOi, and 22 parts of allyl esters of coconut fatty acids, and adding a little water as needed on the rolls. The resulting flakes suds and cleanse well and do not give objectionable curd in 20 grain water. The ratio of soap to synthetic detergent in these flakes is about 1.8:1, and the ratio of synthetic; detergent to allyl ester is about 1.3:1.

Example 8.—Detergent flakes are made by the procedure of Example 6, using 33 parts of sodium soap made from tallow and containing about 3% water, 44 parts of the mixed coconut fatty acid mono-esters of l,2-dihydroxy-propane-3-sodium sulfonate, and 24 parts of allyl myristate. The flakes suds and clean well and do not give objectionable curd in 20 grain water. The ratio of soap to synthetic in these flakes is about 0.7:1, and the ratio of synthetic to allyl ester is about l.8:l.

2,484,680

In the above examples, reference has been made to use in water of 20 grains of hardness per gallon. It is to be understood, however, that 20 grain water is referred to only as being representative of hard waters in general. According to my experience and investigations, my ternary detergent composition is effective in hard water of any municipal water system or any domestically used water source of which I am aware.

Besides possessing resistance to curd formation in hard water, products of the present invention dissolve at a desirable rate in the water, suds profusely, and cleanse efficiently. Addition of the allyl ester to the soap-synthetic detergent mixtures, as specified in the application, tends in general to increase the sudsing power of the .composition. However, excessive additions of the ester are to be avoided, as they may decrease sudsing power, harm the desired physical properties of the detergent bar, flake or other product, and Interfere with handling in some of the common soap manufacturing processes.

It is especially noteworthy that the bar products of my invention have a definite advantage over bars consisting in very large measure of synthetic detergent in that they do not dissolve too rapidly, do not become soft, are more soap-like in appearance and feel, and behave more like soap in processing operations, and produce a lather which is generally similar in structure and feel to that of soap, being unlike that produced by the synthetic alone.

The amount of allyl ester that can advantageously be used is to a degree dependent upon the nature and amount pf synthetic detergent present in the composition. The most useful products result when the amount of allyl ester exceeds one sixth of, but is not greater than, the amount of synthetic detergent present and constitutes at least 2 per cent of the combined weight of soap, synthetic detergent and allyl ester.

Most of the above examples cover compositions in which the ratios of essential ingredients come within the preferred ranges, that is, a ratio of soap:synthetic from about %:1 to about 4:1, and a ratio of synthetic:allyl ester from about 1,^:1 to about 6:1. The advantages of my discovery, however, are to be realized even in compositions falling outside the preferred ranges of proportions, and accordingly compositions coming within the ratios of soap:synthetic of about to about 8:1 and of synthetic:allyl ester of about 1:1 to about 10:1 are contemplated as part of the broad invention, the illyl ester constituting at least 2 per cent of the combined weights of soap, synthetic and ester. Optimum results in the case of each composition may be realized by adjustment of the ratios used depending on the types of soap, synthetic detergent and ester employed.

As indicated above, the physical form of the compositions is not a limitation of the invention and may be varied in well known manner. In some instances, however, it may be necessary to adjust temperature conditions or moisture content of the mixture to give a product of the desired consistency for handling in the various processing operations required in the development of the desired physical form. Such adjustments of course are well within the scope of those skilled in the art.

The manner of mixing the ingredients is not a limitation of the invention. Any suitable mixing device such as a series of milling rolls ordi8 narily used in mixing plastic soap with added ingredients or crutching mechanism of high mixing efficiency as employed in mixing more fluid constituents may be employed to effect homogeneity in the mixture of ester, soap, and synthetic detergent.

Furthermore, it is within the scope of my invention that instead of mixing independently prepared allyl ester and sulfonated monoglyceride when a mixture of these two compounds is to be used in conjunction with soap, the said mixture of these two compounds may be obtained directly by suitable choice of the process of manufacturing the said sulfonated monoglyceride. For example, I may prepare the sulfonated monoglyceride by treating an allyl ester with chlorosulfonic acid, and, by suitably controlling the conditions of sulfonation, i. e. time, temperature or sulfonating agent concentration, a reaction product containing the desired proportion of unsulfonated allyl ester may be obtained.