US2843550A - Synthetic detergent compositions - Google Patents

Description

able for the preparation of the detergent com -estate.

United States {Email SYNTHETIC DETERGENT CQMPGSITIONS Richard D. Stayner, Berkeley, Calif, assignor to Cali fornia Research Corporation, San Francisco, Calif, a corporation of Deiawnre No Drawing. Application March 2, was Serial No. 413,713

Claims. (Cl. 252-152) This invention relates to anionic synthetic detergent compositions capable of producing good quality, stable, and persistent foam upon being dissolved in water in concentrations conventionally employed in household washing and in commercial laundry practice.

Aqueous wash solutions of a number of known anionic detergents when employed in non-automatic and auto matic agitator-type washing machines, although efficient insofar as their detersive or cleansing action is concerned, produce but very little foam in the presence of soil, and

this foam ordinarily has a lacy, unstable texture, and

readily collapses and disappears during the agitation of the contents of the tub of a washing machine.

it is generally extremely difiicult, if not impossible, to predict the foam characteristics of an anionic detergent containing in addition to a sulfate or a sulfonate group an intermediate linkage, e. g., an ester, an ether, or an amide linkage. Nor can one foretell with a sufficient degree of certitude whether or not the addition of a compound found to be capable of improving the foam performance of a certain particular type or group of anionic organic sulfate or sulfonate detergents will similarly influence the foam behavior of another type or group of anionic sulfate or sulfonate detergents containing an additional or a different intermediate linkage. It is, therefore, evident that formulation of synthetic anionic detergent compositions possessing a high degree of Washing efficiency and at the same time capable of satisfactory foam performance substantially equivalent to that of the better household laundry soaps presents a difficult problem to those engaged in the detergent art.

Water-soluble alkylolamide sulfates of straight-chain saturated C to C fatty acidsin which the hydrophobic organic group is linked to the hydrophilic sulfate group through an amido linkage have been known in the art as effective anionic detergents; however, their foam performance is not as satisfactory as that of the conventional laundry soaps, and while they produce an adequate volume of a fair quality foam, the persistence of this foam under conditions of agitation is low. Consequently, the art has been seeking a long time for the ways to improve their foam characteristics so as to make the detergent compositions containing these organic sulfates acceptable to consumers.

I. have found that synthetic detergent compositions containing as their active organic detergent component a member of a certain hereinafter defined group of water-soluble sulfated alkylolamides of straight-chain saturated C to C fatty acids, such as are commonly derived from coconut oil and containing, in addition, a straight-chain saturated C 0 to C aliphatic alcohol as a foam improving agent, upon dissolution in water in dilute concentrations from.0.l to 0,4 commonly employed in the laundering practice, will produce c pious, stable andpersistent foam whenemployed to wash soiled clothes in the tub of awashingmachine.

The structure of fattyiacidialkylolamide sulfates suit;

2,843,550 Patented July 15, 1958 ice of my invention can be represented by the following formula:

in which R is a straight alkyl chain having 7 to 17 carbon atoms; R is a hydrogen, or a C to C alkyl group; R" is a hydrogen or a methyl group and preferably a hydrogen; M is an alkali metal and preferably sodium; and x is an integer from 1 to 3 and preferably from 1 to 2. In addition, R may also be the grouping: -i-i (i3iii{}JIFSG M shown in the above formula. These organic sulfates and their preparation have been described in the art, for instance, in German Patent No. 633,334.

The straight-chain saturated C to C aliphatic alcohols, added to the detergent compositions to improve their foam performance, are present in amounts which may range from about 5 to about based on the weight of the active alkylolamide sulfate, and those containing from 12 to 16 carbon atoms in their molecule (lauryl, myristyl, and cetyl) are particularly effective in enhancing foam performance of detergent compositions containing fatty acid alkylolamide sulfates as their organic active component.

The organic alkylolamide sulfate detergents have been produced in the past from coconut oil fatty acids containing from 8 to 18 carbon atoms in the molecule. However, in view of the fluctuating market and the frequently recurring scarcity of coconut oil, the employment of coconut oil fatty acids tends to increase the cost of production of detergent compositions containing a kylolamide sulfates as their organic active component. The saturated C to C fatty acids such as are obtainable by known hydrogenation procedures from tallow and usually containing from 60 to 70% by weight of stearic acid heretofore have been considered unsuitable for the formulation of detergent compositions capable of producing satisfactory stable foams. Dilute aqueous solutions (0.1 to 0.4% concentration) of the detergent compositions containing sulfated alkylolamides of hydrogenated tallow fatty acids produce but a little volume of an unstable, lacy foam, and the addition of straight-chain saturated C 0 to C aliphatic alcohols in the: same manner as described hereinabove with reference to sulfated alkylolamides of coconut oil fatty acids is ineffective in producing adequate foam volume.

Addition of C to C alkylolamides of saturated fatty acids such as lauric ethanolamide or lauric isopropanolamide reported in the art as additives for the improvement of foam properties of certain classes of synthetic anionic detergents is found inadequate to bolster and to stabilize the foam of sulfated alkylolamides of hydrogenated tallow fatty acids. It is-true that improved foam persistence, i. e., continuous presence of foam in the tub of a washing machine during the agitation cycle of at least 20 minutes, may be achieved by such an addition, but the static stability and the quality of the foam are inordinately poor. The foam is extremely unstable and lacy in its texture, and readily collapses in the presence of soil in the course of agitation.

I have found that by employing sulfated alkylolamides of hydrogenated tallow fatty acids as the essential organic detergent ingredient of the formulations of my invention and by replacing a portion of these sulfated alkylolamides not exceeding 8 5% by weight of the well-known C to C monoalkyl benzenesulfonates, an ample volume of foam of a satisfactory static stability and quality will be and p'rererably the C te C straight chain saturated aliphatic alcohols present in these formulations in accordance with my invention will secure an adequate degree of persistence and stability of this foam during the agitation of the wash solution containing soiled articles or fabrics in the tub of a washing machine.

Sulfated alkylolamides of hydrogenated tallow fatty acids employed in formulating the detergent compositions of my invention are prepared by reacting suitable pri mary or secondary straight-chain C to O, alkylolamines, and preferably C to C alkylolamines, with saturated C to C fatty acids produced from hydrogenated tallow, sulfating the resulting alkylolamides and neutralizing the sulfation product with a suitable base, aqueous sodium hydroxide or sodium carbonate being preferably employed for this neutralization.

In view of the comparatively low cost of C to C monoalkyl benzene sulfonates, they may be employed in the detergent formulations of my invention to replace the sulfated alkylolamides of C to C fatty acids, irrespective of the original source of these acids: coconut oil, tallow, cottonseed oil, and the like, and in amounts up to 85% by weight of the total organic detergent component. When the sulfated alkylolamides are derived from hydrogenated tallow, addition of these monoallryl benzene sulfonates, and particularly in amounts from about 50 to about 85% by weight of the total organic detergent component, is particularly effective in securing the desirable volume of foam. These formulations contain, furthermore, from 5 to 70% of a C to C normal saturated aliphatic alcohol, based on the weight of the sulfated alkylolamides, as an agent for the enhancement of foam persistence. If monoalkyl benzene sulfonates are present in the detergent composition, the weight ratio of these sulfonates to the sulfated alkylolamides of fatty acids may be as high as 3:1 or even higher, ratios of lzl and 2:1 furnishing the best results as regards foam properties (performance) and washing efliciency (detergency). The preparation of C to C monoalkyl benzene sulfonates is well known to those skilled in the art and is described, for instance, in U. S. Patent No. 2,477,383, issued to A. H. Lewis, and U. S. Patent No. 2,218,472, issued to Kyrides. As pointed out hereinbefore, the presence of these C to C alkyl benzene sulfonates in a composition containing active sulfated alkylolamides of fallow fatty acids, as well as in compositions containing active sulfated alkylolamides of hydrogenated cottonseed oil fatty acids, soybean oil fatty acids, and the like, insures an adequate foam stability and a satisfactory foam quality, whereas in those compositions containing sulfated alkylolamides of coconut oil fatty acids, their em ployment effects a substantial reduction of costs.

The excellent foam properties of the detergent compositions of my invention are not affected by the presence of detergent builders commonly employed in anionic detergents, and, in particular, in heavy-duty detergents such as are usually employed in the laundering practice. Detergent builders are water-soluble inorganic salts such as neutral salts of strong acids (chlorides or sulfate component (which may, if desired, contain a detergent monoallryl benzene sulfonate) and to the C 5 to normal saturated aliphatic alcohol as the foam-improving 4 agent, may contain in each 100 parts by Weight, based on the content of solids in a particular composition, from 60 to 90 parts by weight of water-soluble inorganic salt builders, the sodium salt builders being usually preferred. These sodium salts include sodium carbonate, sodium tripolyp'nosphate, tetrasodiurn pyrophosphate, sodium sulfate, bi; x, sodium chloride, sodium silicates, etc.

Well-known alkylolamide foam improvers such as lauric isopropanolamide and lauric ethanolamide may be added if so desired to my detergent formulations to enhance the tolerance of soil by the foam. These additions in no way diminish the beneficial effect of the presence of a normal C to C saturated aliphatic alcohol agent on foam persistence while washing soiled laundry or dishes under conditions of agitation.

if desired, other conventionally employed additives such as anti-calting agents, optical bleaches, perfume, and coloring agents may be present in the detergent compositions of my invention. Sodium carboxymethyl cellulose or sodium salts of celluronic acids may also be present in small amounts as extenders, as well as for the purpose of preventing re-deposition of the soil. N alkyl glycines and diglycines which act as skin emollients and prevent skin rashes and erythemas may be likewise added. These additives are usually present in amounts less than 5% by weight, based on the total content of solids in the detergent composition, and in all events are employed in such amounts as not to interfere with the improvement of the foam properties described hereinbefore.

Generally, the blending of the various ingredients of my improved detergent compositions is carried out by mixing the ingredients to form a solution or slurry, and then drying the resulting mixture to the solid particle form, or evaporating it to form a paste, or, yet, diluting it to produce a liquid concentrate. When a detergent composition is to contain the combination of fatty acid alkylolamide sulfates and alkyl benzene sulfonates as its active ingredient, it is preferred to sulfonate the alkyl benzene stock first (for details of sulfonation, see bulletin of Oronite Chemical Company of San Francisco, California, published in 1950 and entitled, Alkane-Product and Processing Information), and then to add the fatty acid alkylolamides to the sulfonation reaction mixture. The alkylolamides are sulfated by the unreacted sulfuric acid in the sulfonation reaction mixture. Thequantity of the sulfonating agent required for the preparation of a particular mixture of alkyl benzene sulfonic and acid sulfates of alkylolamides of fatty acids is governed by the desired weight ratio of detergent organic sulfates to alkyl benzene sulfonates in the final neutralized product. If desired, the sulfonating agent, e. g., fuming sulfuric acid, may be employed in such an amount that the unreacted sulfuric acid in the sulfonation product mixture would be insufficient to sulfate all of the alkylolamides, and a portion thereof thus may be permitted to remain in the liquid mixture of sulfated alkylolamides and alkyl benzene sulfonic acid, and would tend to improve the soil tolerance of the foam formed by aqueous wash solutions of the final detergent formulations. The resulting mixture of acids is then neutralized. Thereupon the neutralized slurry or solution receives the addition of the normal saturated C to C aliphatic alcohol and also detergent builders and such other additives as may be required, and finally is converted to the desired form: solid particles, or a paste, or a liquid concentrate. By first sulfonating the alkyl benzene stock in a known manner, and then sulfating the alkylolamides in the sulfonation reaction mixture, a superior product is obtained with all ingredients being uniformly distributed throughout the final product whether offered in the form of solid particles, a semi-solid paste, or a liquid concentrate.

Several series of foam evaluation tests have been carried out. These series comprised-numerous benchf tests in the laboratory using dilute aqueous wash solutions of the detergent compositions prepared in accordance with my invention. The active organic portion of each 100 parts of the solid dry particulate formulations employed for these tests was equal to from 20 to 22 parts by weight and consisted of sodium salts of sulfated alkylolamides of C to C fatty acids, sodium 0,; to C monoalkyl benzene sulfonates, and a straight-chain C to C saturated aliphatic alcohol, e. g., normal decanol, dodecanol, tetradecanol, hexadecanol, and octadecanol. In addition, the same solutions were tested in an agitator-type non-automatic washing machine under the conditions closely approximating those occurring in the conventional operation of a domestic washing machine. Data from several representative tests of a series designated as Series A are offered in the following Table I in order to illustrate the advantages of the improved detergent composition of the present invention. Sodium C to C polypropylene benzene sulfonate was employed as a representative (3,, to C monoalkyl benzene sulfonate in the tests of this series. The sulfated alkylolamides employed were those amides of fatty acids derived from hydrogenated tallow, and the alcohols selected as representative alcohols effective in securing better foam persistence were dodecanol and hexadecanol. Detergent builders were present in the following amounts: 30 parts by Weight of sodium tripolyphosphate; parts by weight of tetrasodium pyrophosphate; 5 parts by weight of sodium silicate; the remainder to make 100 parts by weight being sodium sulfate. The ratio of Na O to SiO in the sodium silicate was 1:3.2. Solid, dried particles of the detergent formulation were dissolved in soft water from the laboratory tap (50 p. p. m. of Ca-Mg hardness) at 120 F. to make up 500 ml. of a 0.15% solution in 2-liter beakers. The solutions were then tested at the bench by agitating the contents of the beakers with the aid of propeller-type stirrers for one minute. The contents were then allowed to stand for one minute and foam heights in millimeters were determined. In another 15 minutes after the termination of the agitation, the foam heights were measured again. Stability of the foam was rated by observing the rate of oil ate between Poor and Good was rated as Fair. The size of the foam bubbles and the body or feel thereof were also observed. Foam of a Good quality is made up of uniformly small-sized, dense-bodied bubbles and has high bulk viscosity. It is white and opaque. Foam of a Poor quality has large-sized bubbles, a low bulk viscosity and tends to be lacy. It is, furthermore, greyish in color and transparent. Foams, the stability of which lies between Poor and Good, were rated as Fair.

In the parallel washing machine tests of the same series, carried out for the purpose of determining foam persistence, the bowl or tub of the machine was filled with the wash solution and charged with a load of soiled cotton towels. In each test run the contents were agitated under identical conditions and at the same temg'terol'lii'fi (l2tl-l25 F). Solutions were prepared using hem soft water (50 p. p. m. of Ca-Mg hardness) and hard water (300 p. m. m. of Ca-Mg hardness). Foam was observed at regular intervals, and its persistence was rated. When the suds disappeared from the surface of the wash solution in the tub in less than 5 minutes after the beginning of agitation, the persistence was given a rating of 1. When from 5 to 10 minutes was required for the disappearance of the foam, the persistence was rated as 2. When from 10 to 20 minutes was required for the disappearance of the foam, its persistence was assigned a rating of 3. The foam which lasted for 20 minutes under the conditions of operation, but was less than /2 inch high above the surface of the liquid in the tub, was given a persistence rating of 4. When, after 20 minutes of operation, the height of the foam was from /2 to 1% inches above the surface of the liquid, the persistence was assigned a rating of 5. When, after 20 minutes, the foam retained a height from 1% to 3 inches above the surface of the liquid, the persistence was rated as 6. Finally, when the foam after 20 minutes stayed at a level higher than 3 inches above the surface of the liquid, the persistence was asfoam decay under mechanical stress as by blowing on a signed a maximum rating of 7.

TABLE I Foam evaluatzon data Foam Performance Bench Tests Washing Machine Foam-Improv- Monoalkyl Te t Test Sulfated Allcylolamide of Hydro- Parts ing Straight- Parts Benzene Run genated Tallow Fatty Acids by chain Saturated by Sulfonate No. Wt. Aliphatic Wt. in Parts Foam Height Alcohol by Wt. in mm. In Soft In Hard Foam Foam Water, Water,

Stability Quality p. p. m. 300 After After p. p. m 1 min. 15 min.

1 Ethanolamidc 10 Dodecanol. 2 10 82 68 2 do. 5 do 2 15 83 67 3 10 Hexadecanoh. 2 10 82 67 4 3 d 2 17 8O 68 5- 10 10 82 48 6- 5 15 86 57 7 17 82 68 8- 15 83 9- 73 30 10 18 Hcxadecanol 2 60 55 11..- I i. one 20 87 68 12..- n-Propanolamide. 10 Dodocanol. 2 10 80 68 13..- do 10 Hexadecanol. 2 10 82 14 d0 10 None 10 80 50 15 Diethanolamide.. 5 do .1 15 74 57 16 do 5 Hexadecanol. 2 15 48 40 17. do. 5 Dodecano1 2 15 75 40 18. do 10 do 2 10 65 48 19 Diethanolamide and monoetha- 10 v d0 2 10 89 Good nolamide (weight ratio 1:1). 20 Ethanolamide 8 .do 2 12 do.

small volume of foam gently with air: an unstable foam rapidly collapses when blown upon. High degree of stability, when foam withstands being blown upon, was rated at Good; stability of weak, almost immediately collapsing foam was designated as Poor; stability intermedi- The results offered in the table strikingly illustrate the advantages of employing detergent formulations of my invention whenever formation of a dense, stable, and persistent foam is desirable in the laundering operations. Thus, the team of the formulation; which contained sulfated alkyloamides of hydrogenated tallow fatty acids as the sole active organic detergent component, in the absence of added normal saturated C to C aliphatic alcohol, produces but a very low volume of foam of Poor quality and Poor static stability (test run #9), an improvement, however, being noted upon addition of a normal C to C saturated aliphatic alcohol (test run #10). When alkyl benzene sulfonate was the only organic detergent and in the absence of a normal saturated C to C aliphatic alcohol, the foam stability and foam quality were very poor (test run #11). When the combination of a sulfated alkylolamide detergent derived from tallow fatty acids with an alkyl benzene sulfonate detergent was employed in the absence of a normal C to C saturated aliphatic alcohol (e. g., test runs and #6), the foam still lacked good quality and static stability. Surprisingly, however, when similar combinations received an addition of a normal C to C saturated aliphatic alcohol (test runs Nos. 1, 2, 3, 4, 8, 12 and 13), an adequate volume of Good quality, stable foam was produced and the foam persisted under the conditions of agitation.

The foam produced by the formulations, the active organic portion of which contains at least 15% by Weight of sulfated alkylolamides or hydrogenated tallow fatty acids in combination with up to 85% of C to C monoalkyl benzene sulfonates, and furthermore containing from 5 to 70% by weight, based on the sulfated alkylolamide ingredient, of a normal saturated C to C aliphatic alcohol, is similar in appearance and feel to the suds of conventional good-quality household soap.

Good detergency was obtained by using aqueous wash solutions (0.1 to 0.4% concentration) prepared with these formulations, as determined by the Launderometer Method, particularly when washing soiled cotton goods.

in similar series of test runs (B) and (C) employing detergent formulations containing: (Series B), sulfated alkylolamides of coconut fatty acids as the only organic detergent component and from 5 to 70% by weight thereof of a normal saturated C to C aliphatic alcohol; and (Series C), a combined organic detergent component,

at least 15% by weight thereof being sulfated alkylolamides of coconut oil fatty acids and the remainder being C to C alkyl benzene sulfonates, together with from 5 to 70% by weight of a normal saturated C to C aliphatic alcohol, based on the content of sulfated alkylolamide detergent. In each of these Series (B) and (C), good foam performance and detergency have also been observed. Dilute aqueous solutions of the formulations containing in the organic detergent portion at least 15% by weight of sulfated alkylolamides of hydrogenated tallow fatty acids and up to 85% by weight thereof of alkyl benzene sulfonates, and further containing from 5 to 70% by weight, based on the alkylolamide sulfate, of a normal saturated C to C aliphatic alcohol (Series A) are found to be slightly more effective in detergent action, particularly at low use-concentrations in hard water, than similarfdilute solutions of formulations containing sulfated alkylolamides of coconut oil fatty acid as the only detergent (Series B), or containing blends thereof with C to C alkyl benzene sulfonates (Series C).

It is known that detergent compositions containing C to C monoalkyl benzene sulfonates as the sole active organi e component suffer from the drawback of unsatisfactory foam stability. Hence, it is entirely unexpected that the detergent compositions, in which the active organic component is a combination of these sulfonates with sulfated alkylolamides of C to C saturated fatty acids, derived from coconut oil or from taliow or from other suitable organic materials, and which contain C to C normal aliphatic alcohols in accordance with the invention, upon being dissolved in water to form dilute aqueous wash solutions, produce foams of excellent quality, similar in texture to the soapsuds, and capable of lasting (persisting) throughout the duration of a complete washing cycle in the bowl of an agitator-type Washing machine.

I claim:

1. A detergent composition consisting essentially of alkali metal salts of sulfated C 43 alkylolarnides of C C hydrogenated tallow fatty acids, alkali metal Cry-C15 monoalkyl benzene sulfonate detergent, the former being present in an amount, by weight, of about 15% to 50%, and the latter, 50% to 85%, by weight, of the total of the two, and as a foam-improving agent, about 5% to 70%, by weight, based on the sulfated alkylolamide salt, of a normal, saturated C -C aliphatic alcohol.

2. A detergent composition consisting essentially of alkali metal salts of sulfated hydrogenated tallow fatty acid ethanolamide, alkali metal C C monoalkyl benzene sulfonate detergent, the former being present in an amount, by weight, of about 15% to- 50%, and the latter, 50% to 85%, by Weight, of the total of the two, and as a foam-improving agent, about 5% to 70%, by weight, based on the sulfated alkylolamide salt, of a normal, saturated C -C aliphatic alcohol.

3. A "built detergent composition consisting essentialiy of about 10 to by weight, of the detergent com position of claim 1 and about 60 to 90%, by weight, of water-soluble inorganic salt builders.

4. The composition of claim 1 wherein the alkali metal of the sulfated alkylolamides and of the C -C monoalkyl benzene sulfonate detergent is sodium.

5. The composition of claim 4 wherein the C -C monoalkyl benzene sulfonate detergent is a (I -C monoalkyl benzene sulfonate detergent.

References Cited in the tile of this patent UNITED STATES PATENTS OTHER REFERENCES Perry and Schwartz: Surface Active Agents, 1949,

, pages 117, 118.

Claims (1)

1. A DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF ALKALI METAL SALTS OF SULFATED C2-C3 ALKYLOLAMIDES OF C14C18 HYDROGENATED TALLOW FATTY ACIDS, ALKALI METAL C9-C18 MONOALKYL BENZENE SULFONATE DETERGENT, THE FORMER BEING PRESENT IN AN AMOUNT, BY WEIGHT, OF ABOUT 15% TO 50% AND THE LATTER, 50% TO 85%, BY WEIGHT, OF THE TOTAL OF THE TWO, AND AS A FOAM-IMPROVING AGENT, ABOUT 5% TO 70%, BY WEIGHT, BASED ON THE SULFATED ALKYLOLAMIDE SALT, OF A NORMAL, SATURATED C10-C18 ALIPHATIC ALCOHOL.