US2691636A

US2691636A - naoocchs

Info

Publication number: US2691636A
Authority: US
Publication date: 1954-10-12
Anticipated expiration: 1971-10-12

Description

Patented Oct. 12, i954 California Research Corporation, San Fran cisco, Caiif., a corporation of Delaware No Drawing. Application December 11, 1952,

5 Claims. I

The present invention relates to anionic syn thetic detergent compositions. More particularly, it relates to improved anionic alkyl sulfate detergent compositions capable of producing dense, stable foam when aqueous solutions of these compositions are employed in conventional concentrations for household or commercial laundering.

Small scale users of synthetic anionic detergents insist that the detergent products be capable of producing substantial lather or foam and that this foam remain stable during the washing process. The average housewife persists in the belief that satisfactory detergency and formation of copious foam go hand in hand and seeks detergent products which would produce rich, dense lathers or foams constituted by little bubbles and on contact with the hand would give the feeling of a cream-like consistency of soap suds. This persistent prejudice is responsible for the slow customer acceptance of synthetic anionic detergents for laundering purposes, particularly in the home, since many efiicient detergents have but little foaming power, and also since the foam produced by them is rather poor in texture and lacy, and does not possess sufficient stability.

In U. S. Patents Nos. 2,166,314 and 2,166,315, Martin proposed to add higher saturated C8-Cl8 aliphatic alcohols to compositions containing sulfated alcohol detergents for the purpose of improving the sudsing properties of th se compositions. However, such an addition, while improving the sudsing ability, brings about certain disadvantages, namely: (1) a relatively large portion of the aliphatic alcohols added to the neutralized slurry of alkyl sulfate detergent lost in the subsequent drying of the slurry; (2) a fatty odor characteristic of these alcohols is imparted to the product.

I have now found that desirable foaming characteristics and satisfactory foam stability can be impart-ed to detergent compositions which contain as their surface-active ingredient an anionic water-soluble salt of a straight-chain 312-022 alkyl sulfuric acid, by adding to these compositions a minor amount of a salt of a primary C12-Ci8 straight-chain alkyl amine and an organic acid from the group consisting of higher C12-C1s saturated fatty acids, Gil-C18 monoalkyl benzene sulfonic acids and Ciz-Cis straight-chain monoalkyl sulfuric acids. In general, from about 0.5 to about 10% by weight of this salt, based on the solid constituents of the detergent composition, sufiices to secure a satisfactory, stable foam.

When aqueous solutions of the detergent com- Serial No. 325,441

22 positions containing as their surface-active ingradient said water-soluble salt of a C12C22 straight-chain alkyl sulfuric acid and the aforementioned alkyl ammonium salt additive are employed to wash fabrics, in concentrations conventional in the laundering practice (0.1 to 0.4%),

they produce a rich, creamy foam of densely agglomerated small bubbles readily recognizable by squeezing through the fingers. This foam retains its stability for relatively long periods of time, and the detergency of the wash solutions containin these detergent compositions not only is unaffected by the presence of the alkyl aininonium salt additive which promotes and stabilizes the foam, but frequently is enhanced thereby.

As stated hereinbefore, the detergent compositions of my invention capable of producing satisfactory, stable foam contain as their surface-- active ingredient water-soluble salts of an alkyl sulfuric acid in which the hydrophobic alkyl radical is constituted by a straight carbon to carbon chain of 12 to 22 carbon atoms.

The term a salt of an alkyl sulfuric acid, as employed in this specification, includes alkyl sulfates, and alphaand beta-hydroxyalkyl sulfates. In all of these alkyl sulfates, the hydrophilic group occupies the terminal position on the carbon chain.

ihe term a water-soluble salt as used in this specification is intended to include all watersoluble detergent salts of C12-C22 allryl sulfuric acids, namely, inorganic alkali metal salts, alkaline earth metal salts, e. g., calcium and magnesium; ammonium salts; alkyl and allzylol an1- moniurn salts, e. g,, triethanol ammonium salts.

Generally speaking, the N-n-alkyl ammonium salts which promote foam formation and stabilize the foam of alkyl sulfate detergents in accord ance with the invention, can be formed by reacting the organic base, i. e., primary normal Q2 31;

alkyl amine, with an acid from the group consisting of higher saturated ClE-CZS fatty acids. Gil-C18 monoalkyl benzene sulfonic acids, and 612*(318 straight-chain monoalkyl sulfuric acids.

The ammonium salts of saturated Cir-C13 fatty acids, CQ-Cia monoalkyl benzene sulfonic acids and C12-C1a straight-chain monoalkyl sulfuric acids can also be obtained by reacting asalt of the primary amine, e. g., a hydrochloride, a for mate, or an acetate, with a water-soluble inorganic salt of a fatty acid, an alkyl benzene sulfonic acid, or an alkyl sulfuric acid. In so doing a suitable solvent, e. g., ethanol, will be employed 55 to separate the phase containing ammonium salt,

dissolved in ethanol or other appropriate organic solvent, from the phase containing the watersoluble salt such as NaCl, NaOOCCI-h, and the like.

To illustrate: A primary straight-chain C12-Cl8 fatty amine, e. g., lauryl amine, may be melted together with an equimolar amount of a higher 012-018 saturated fatty acid, such as myristic acid. In this case the product will be N-n-dodecyl ammonium myristate. The same ammonium salt may be obtained by dissolving the aforementioned reactants in ethanol or other appropriate inert solvent, and substantially evaporating the solvent medium.

In order to obtain the foam stabilizing salt of a C12 primary fatty amine and a C12 monoalkyl benzene sulfonic acid, the amine is reacted with the sulfonic acid and yields the desired ammonium salt. One may also obtain this salt by reacting a hydrochloride of the amine, e. g., octadecyl amine hydrochloride, with sodium monoalkyl benzene sulfonate in ethanol as a solvent medium. Sodium chloride is precipitated, and, upon filtering and evaporating the alcohol, the desired octadecyl ammonium sulfonate additive is recovered. Salts of 012-018 fatty amines and alkyl sulfuric acids may be prepared in a similar manner. For instance, a salt of the primary amine, e. g., N-n-tetradecyl ammonium acetate, can be reacted with an alcohol sulfate, e. g., sodium dodecyl sulfate, and, upon separation of phases with the aid of a suitable solvent, will yield the desired foam-promoting and foam-stabilizing additive, namely, N-n-tetradecyl ammonium alkyl sulfate.

In addition to the surface-active alkyl sulfates and the foam promoting alkyl ammonium salt additives, the detergent compositions of the invention may contain builders conventionally employed in conjunction with anionic detergents such as inorganic sulfates, phosphates and silicates, extenders such as sodium carboxymethyl cellulose, optical bleaches, perfumes, etc. These additives are employed in amounts readily determinable by those skilled in the art to suit the requirements of each particular formulation. Ordinarily, aqueous solutions (in 0.1 to 0.4% concentration) of detergent compositions which contain in each 100 parts by weight from to 50 parts of the surface-active ingredient, the balance being the aforementioned inorganic builders and other conventional additives, will produce good, stable foam upon adding thereto from 0.5 to 10% by weight of the foam-promoting ammonium salt.

In heavy-duty, all-purpose detergent compositions generally containing from 15 to 30 parts of the surface-active ingredient in each 100 parts of solid constituents, from about 0.5 to 5% by weight, and preferably from 1.0 to 2.5% by weight, of the foam-promoting ammonium salt provides the desired effect.

I have furthermore found that salts of C12-C22 straight-chain alkyl sulfuric acids which constitute the principal surface-active ingredient of my improved detergent compositions may be replaced in part by compatible water-soluble salts of (la-C18 monoalkyl benzene sulfonic acids, and preferably C12-C15 monoalkyl benzene sulfonic acids. So long as at least of the combined weight of surface-active ingredients in such modified composition is constituted by the water-soluble C12-C22 alkyl sulfate, the foam characteristics will be improved by the introduction of from about 0.5 to about 10% by weight of the ammonium salt additive in accordance with the invention. This til represents an important finding, since the fatty alcohols reported in the art as suitable agents for improving the foaming characteristics of alkyl sulfate detergents are ineffective in detergent compositions containing alkyl benzene sulfonate as the only surface-active ingredient. Furthermore, salts of fatty amines and organic acids, disclosed in the present specification as effective additives for improving the foaming characteristics of alkyl sulfates are likewise inefficient in detergent compositions where an alkyl benzene sulfonate is the sole surface-active constituent.

A number of tests was carried, out with the various formulations prepared in accordance with my invention and their results were compared with the results obtained employing other known compositions of the trade. Stock solutions for these tests were prepared, using a small amount of isopropanol, and heating if necessary, to dissolve a sample of the detergent formulation in order to obtain a 5% solution in distilled water. In a representative test series the composition contained 24% by weight of total surface-active ingredients, including the foam-promoting ammonium salt; 55% of sodium tripolyphosphate; and 21% of sodium sulfate. By dissolving 20 g. of such a. 5% solution in 500 ml. of warm water to F.) in a 2 liter beaker, a 0.2% solution was obtained for actual use in the tests.

The tests were carried out in accordance with the following technique: The test solution was agitated vigorously for 1 minute (with the aid of a mechanically driven propeller stirrer) and then allowed to stand for an additional 1 minute, whereupn the foam height in millimeters was measured. Heights of more than 30 mm. were rated as high; heights between 20 to 30 mm. were rated as medium; and those of less than 20 mm. were rated as low. Fifteen minutes after the agitation was terminated, the foam heightwas measured again, and the stability and quality of the foam were ascertained.

The foam stability was rated by blowing on a small volume of foam gently with air. In the case of unstable foam, this procedure resulted in a rapid decay (collapse) of foam bubbles. The quality of the foam, 1. e., the size of the foam bubbles and the feel, or body, of the foam, was rated by comparing them with the foams produced by two formulations: detergent composition A which contains 10% by weight of sodium C12-C14 alkyl sulfate, 50% by weight of sodium tripolyphosphate, 10% by weight of sodium C12- C15 alkyl benzene sulfonate, 2% by weight of lauryl alcohol, the balance to make 100% being Nazsoi builder; and detergent composition B which contains 24% by weight of sodium ClZ-Cl5 alkyl benzene sulfonate; 55% by weight of sodium tripolyphosphate and 21% by weight of NazSO. builder. Composition A produces excellent creamy, small size foam bubbles and a heavy stable dense-bodied suds and its foam stability and quality are, therefore, rated to be Good. Composition B produces lacy, rapidly collapsing foam, and its foam quality and stability are rated Poor. The designation Fair is employed in the specification to rate those foams approaching the stability and quality of the foam formed by composition A.

The experimental data obtained by the aforedescribed evaluation technique clearly show that the addition of salts of primary fatty amines and organic acids described hereinbefore to the anionic detergent compositions containing straightchain (ha-C22 alkyl sulfates provides an improved foam and stabilizes this foam, rendering these detergent compositions attractive for the user.

The following Table I contains the results of a few representative tests selected from the extensive experimental data to illustrate the advantages attained by the detergent compositions of the present invention. In this table, the amounts of the foam-promoting additive are given in per cent of the total Weight of surface-active and inert ingredients of the detergent composition which contained (except where otherwise indicated) 20% of surface-active materials, 55% of sodium tripolyphosphate and 25% of sodium sulfate builder. The surface-active portion of the composition in all tests (except where otherwise indicated) contained. of sodium 012-015 monoalkyl benzene sulfcnate, from 1 to 2% of the foam-promoting ammonium salt, the balance being sodium Chi-C18 straight-chain alkyl sulfates produced by sulfonation of a blend of C14- C18 alcohols, derived in turn by catalytic hydrogenation from the higher fatty acids (or esters thereof) present in tallow.

The foam heights are designated by H-high, M-medium, L-low; foam stability and foam quality are designated by G-good, F-fair and P-poor. The sodium alkyl benzene sulfonate was prepared in accordance with the description of U. S. Patent No. 2,477,383 to A. H. Lewis, by sulfonation of 012-015 polypropylene benzene. The concentration of test solutions was 0.2%, cmploying tap water of 5c p. p. m. hardness CaCOs; A; MgCOs) TABLE I Foam evaluation data [Concentration of Solution: 0.2% in Tap Water] effective for this purpose, as may be seen on the example of tertiary dodecyl anilinium salt of Test #16.

Furthermore, the tests have shown that the primary straight-chain fatty amine must be first reacted with the appropriate organic acid from the particular group of operative fatty, alkyl benzene sulfonic and alkyl sulfuric acids, and only then the resulting salt should be introduced into the mixture of surface-active and inert ingredients. In contradistinction to a practice proposed for cationic detergents, the introduction of N-nalkyl amine, as shown in Test #15 of the table, brings no improvement of foam properties.

Simultaneously with the aforedescribed foam tests, a number of foam samples, produced by detergent compositions containing the ammonium salt additive in accordance with the invention, were tested by letting the suds slide down a vertical glass surface. All of the samples slid down rapidly, indicating a high degree of desirable wetness.

As mentioned hereinbefore, the presence of the foam-promoting ammonium salts of my invention does not affect adversely the detergency characteristics of the anionic alkyl sulfate detergent compositions containing these salts. Frequently their presence appears, in fact, to be beneficial with respect to detergency. A series of tests were carried out by employing a conventional automatic agitator-type washing machine. The solutions employed were those of detergent compositions, prepared in accordance with the Amount Name of Additive of Addi' Comparative Foam Heights Foam Foam tive in percent After 1 min.

After 15 min.

Stability Quality N-n-dodecyl ammonium laurate Same Same n Nn-dodecyl ammonium palmitate Salt of primary n-dodecyl amine and 014-0 3 tallow fatty acids.

Same

Salt of primary Cn-Cm alkyl amine,

and G14-C13 tallow fatty acids.

N-n-dodecyl ammonium 012015 alkyl benzene sulfonate.

Salt of primary 012-0 0 alkyl amine and 012411 alkyl benzene sulfonic acids.

N-n-octadecyl ammonium laurate Salt of primary alkyl amine and fatty acids, both derived from tallow.

Same

N-ntetradecyl ammonium salt of a mixture of 0 2-0 alkyl benzene sulfonic and CLPCIB alkyl sulfuric acids.

N-n-dodecyl amine Tcrtdodecyl anilinium laurate N-n-dodecyl ammonium 3 myristate...-

[Obmore N) M NH NH-H-INHM F IE EH 1 III I I i H I i -H HIH IMEI PMN Fi U1 K 1 mm mmmmmm Wd Q Q Qn QQQQQQ Q Q Q@ QQ DQQQ gtt mo e (we e 1 Primary amine derived from a mixture of coconut fatty acids.

2 Formed by reacting N-n-tetradecyl ammonium acetate with a mixture of benzene Sulfonates and sodium (314-018 alkyl sulfates.

sodium 0 2-015 alkyl 3 Added to a detergent composition containing: 8% by weight of sodium stearyl sulfate, 12% by weight of sodium 012-015 alkyl benzene sulfonate, by Weight of sodium tripolyphcsphate, 21%

by weight of sodium sulfate.

invention and containing 9% by weight of sodium salts of Cli-Cifi alkyl sulfuric acids derived from tallow; 10% by weight of sodium salts of Uri-C15 alkyl benzene sulfonic acids, produced in accordance with the technique described in U. S. Patent No. 2,477,383 to A. H. Lewis; 1% by weight of the foam-promoting ammonium salt additive of the invention; 55% by weight of sodium tripolyphosphate builder; and 25% by weight of sodium sulfate builder. Comparison tests were made with a solution of the previously mentioned detergent composition A. The following concentrations were used: 0.1%, 0.15% and 0.2% in hard water (300 p. p. m.=200 p. p. m. a0Os+100 p. p. m. lvIgCOs) and 0.15% in soft water (50 p. p. m.; 0aCO3:Mg0Oa=-2:1). The machine in each test received a load of 6 pounds of clean cotton towels, having pinned thereto a strip or swatch of cotton, uniformly soiled with a paste of oil, tallow and carbon black. The temperature of the wash solutions was about 140 F., and each test consisted of one washing of 20 minutes duration followed by two -minute rinses. On completion of each test the swatches were removed, and the degree of whiteness obtained was measured in a photoelectric apparatus, free of human equation. The detergency was rated with reference to an arbitrarily chosen detergency standard, namely, the whiteness level secured with the 0.4 concentration of a well-known fatty acid soap in hard water (300 p. p. m), and taken to be equal to 100.

The results of the aforementioned test runs are tabulated in the following Table II:

The actual preparation of the detergent compositions of my invention presents no difficulties. The only condition precedent for the preparation of these compositions is that the foampromoting ammonium salt be prepared first and then only blended with the mixture of surfaceactive and inert ingredients, since, as it was shown, direct addition of primary amine to the detergent composition is ineffective. Blending with the detergent slurry and drying of the blended product are carried out in the conventional manner. The blended slurry may be worked up by spray-drying or drum-drying to give a particulate, flake or chip product, or it may be processed into a paste, or yet may be diluted and sold as a liquid concentrate.

It is to be understood that the aforegiven description and examples are merely illustrative of the invention, and that all modifications consistent with the spirit and scope thereof are included within the terms of the following claims.

I claim:

1. A detergent composition comprising as its surface-active ingredient a water-soluble salt of an alkyl sulfuric acid, having in its molecular structure a straight-chain alkyl radical containing from 12 to 22 carbon atoms, and a minor amount of a salt of a primary Cl2-C18 straight-chain alkyl amine and an organic acid from the group consisting of 012-018 saturated fatty acids, 011-018 monoalkyl benzene sulfonic acids and 012-018 monoalkyl sulfuric acids, said amount being sufiicient to impart stability to the foam of dilute aqueous solutions of said detergent composition of concentrations in the range from 0.1 to 0.4%.

2. A detergent composition, each 100 parts by weight whereof contains from 10 to 50 parts of surface-active ingredients constituted by a water-soluble salt of a straight-chain 012-022 alkyl sulfuric acid, and from about 0.5 to about 1.0%, based on the weight of solid ingredients in said detergent composition, of a salt of a primary CHI-C18 straight-chain alkyl amine and an organic acid from the group consisting of 012-016 saturated fatty acids, 09-018 monoalkyl benzene sulfonic acids and 012-0111 monoalkyl sulfuric acids.

3. A detergent composition, each 100 parts by weight whereof contains from 15 to 30 parts of surface-active ingredients present as a mixture of water-soluble salts of a 012-022 straight-chain alkyl sulfuric acid and of a 011-018 monoalkyl benzene sulfonic acid, at least 25% of the total weight of these surface-active ingredients being constituted by salts of said alkyl sulfuric acid, said detergent composition further comprising from about 0.5 to about 5% by weight, based on the total weight of solid ingredients therein, of a salt of a primary C12-C18 straightchain alkyl amine and an organic acid from the group consisting of ClZ-CIB saturated fatty acids, C9Cl8 monoalkyl benzene sulfonic acids and C12-C18 monoalkyl sulfuric acids.

4. A detergent composition, each 100 parts by weight whereof contains from 15 to 30 parts of surface-active ingredients present as a mixture of water-soluble salts of a 012-022 straightchain alkyl sulfuric acid and of a C9C18 monoalkyl benzene sulfonic acid, at least 25% of the total Weight of these surface-active ingredients being constituted by salts of said alkyl sulfuric acid, said detergent composition further comprising from about 1.0 to about 2.5% by weight, based on the total weight of solid ingredients therein, of a salt of a primary C12-C18 straightchain alkyl amine and an organic acid from the group consisting of 012-013 saturated fatty acids, 09-011 monoalkyl benzene sulfonic acids and ClZ-C18 monoalkyl sulfuric acids.

5. A detergent composition containing in each 100 parts thereof from 15 to 30 parts by weight of surface-active water-soluble salts of a 012-022 straight-chain alkyl sulfuric acid and of a 012-015 monoalkyl benzene sulfonic acid, at least 25% of the total weight of said surface-active ingredients being constituted by salts of said alkyl sulfuric acid, said detergent composition further containing from to '70 parts by weight of inorganic alkali metal builders, and from 1.0 to 2.5%, based on the total weight of the solid constituents in said detergent composition, of a salt of a primary 012-0111 straight-chain alkyl amine and an organic acid from the group consisting of C12-C18 saturated fatty acids, 09-018 monoalkyl benzene sulfonic acids and ClZ-CIB monoalkyl sulfuric acids.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,226,118 De Groote Dec. 24, 1940 2,256,877 Bertsch Sept. 23, 1941

Claims

2. A DETERGENT COMPOSITION, EACH 100 PARTS BY WEIGHT WHEREOF CONTAINS FROM 10 TO 50 PARTS OF SURFACE-ACTIVE INGREDIENTS CONSTITUTED BY A WATER-SOLUBLE SALT OF A STRAIGHT-CHAIN C12-C22 ALKYL SULFURIC ACID, AND FROM ABOUT 0.5 TO ABOUT 10%, BASED ON THE WEIGHT OF SOLID INGREDIENTS IN SAID DETERGENT COMPOSITION, OF A SALT OF A PRIMARY C12-C18 STRAIGHT-CHAIN ALKYL AMINE AND AN ORGANIC ACID FROM THE GROUP CONSISTING OF C12-C18 SATURATED FATTY ACIDS, C9-C18 MONOALKYL BENZENE SULFONIC ACIDS AND C12-C18 MONOALKYL SULFURIC ACIDS.