US2731421A

US2731421A - Tottuwrpmt

Info

Publication number: US2731421A
Authority: US
Publication date: 1956-01-17
Anticipated expiration: 1973-01-17

Description

H DETERGENT COMPOSITIONS Richard D. Stayner,1Berkeley, Califi, assignor to California Research Corporation, San Francisco, Calif., a corporation of Delaware 6 Claims. .(Cl. 252-137) No Drawing.

This inventionrelates to improved anionic synthetic detergent compositions containing as their only effective detergent ingredient a water-soluble alkyl aryl sulfonate. More particularly, the invention relates to those synthetic detergent :compositions which contain a Water-sluble alkyl benzene sulfonate as their sole effective ingredient, and which produce presistent foams of good quality when employed in dilute aqueous solutions to wash soiled fabrics. i i

:The average user of detergents insists on buying detergentlmaten'als capable of producing a substantial volume of suds, owing to a deeply ingrained belief that the formation of copious suds or foam is always accompanied by a good detergent action. The majority of users of detergent products, whether housewives or commercial laundry operators, continue to prefer those materials which produce a dense foam made up by small-size bubbles and giving the familiar feeling of cream-like soapsuds on contact with the hand.

. Because at the present time a large volume of household washing is done by housewives in non-automatic, agitatortype washing machines, the ability of a detergent composition to produce stable foam under static conditions is not a criterion that it would secure a lasting preference of the consumer. Actually the foam, in addition to being similar in physical appearance to soapsuds, must be persistent throughout the washing cycle, despite the continuous agitation of the contents of the bowl or tub of the washing machine, the presence of soil, laundry, etc. At low use concentrations in soft water, this requirement ofwfoam persistence cannot, as a rule, be attained in the case of alkyl aryl sulfona e type detergents, and this inability of producing persistent foams is best exemplified in the use of sodium salts of C9-C1s monalkyl benzene sulfonic acids, otherwise very efficient as detergents. As a matter of fact, the suds produced with solutions of detergent compositions containing such sulfonates as their major active ingredients are extremely short-lived and last but a few minutes, usually from 1 to less than 10 minutes depending upon such factors as: hardness of water, amount of the activesulfonate in the formulation, type and amount of soil present, concentrationof the wash solution and temperature of this latter.

.The C9-C1s monoalkyl benzene sulfonates, the improvement of foam properties whereof is particularly consideredin the present specification, are usually prepared byreacting benzene with a long-chain Cg-Cis aliphatic alcohol, or with a Gil-C18 olefin produced, for instance, by cracking petroleum hydrocarbon gases and polymer: izing the gaseous olefins thus formed, or with an alkyl halide obtained by chlorinating petroleum hydrocarbons of the boiling range of kerosene; sulfonating the resulting alkyl benzene compounds with sulfuric acid, chloro sulfonic acid or sulfur trioxide; neutralizing the resulting sulfonicacid with a base (eg., NaOH or NazCOs); and, finally,- drying the neutralized slurry product (e. g., by spray-drying) to the desired particle form and size. Detergent compositions containing sodium C9-Cm alkyl ben- 2 zene sulfonate as their major organic detergent ingredient ordinarily contain, in addition, from 50 to 90% by weight of inorganic alkaline builders such as polyphosphates and/or sodium sulfate. In the conventional sodium alkyl benzene sulfonate detergent compositions employed for laundering and household washing, from 20 to 50% by weight of these inorganic alkaline builder constituents is constituted by sodium sulfate, which is either present in the product as a result of the neutralization of unreacted sulfuric acid in the sulfonation reaction mixture, or

is added to suit the particular detergent product specification. The balance of the builder portion, from to 20% by weight thereof, is either sodium trlpolyphosphate or tetrasodium pyrophosphate, or a mixture of the two in any appropriate weight ratio. Usually, sodium silicate builders in amounts of the order of 5% by weight of the total solids are present in these detergent formulations. in addition, these sulfonate detergent compositions may contain other conventional additives such as sodium carboxymethyl cellulose extender, optical bleach, perfume, etc. in small amounts readily determined by those skilled in the art to suit the requirements of each particular formulation.

A number of additives have been proposed in the past for the purpose of promoting foam formation in aqueous wash solutions of alkyl benzene sulfonate detergent compositions and imparting the desired persistence to this foam. For instance, small amounts of alkylol amides of fatty acids, e. g., isopropanol amide of lauric acid and ethanol amide of lauiic acid, have been blended into these sulfonate detergent compositions. However, while their addition improved the desired foam persistence, their presence in the sulfonate detergent product caused stickiness and caking of the particles during the spraydrying step of the detergent manufacture and in the storage of the finished particulate product. Furthermore, foams produced by the alkyl benzene sulfonate detergent compositions containing such amides do not attain the desired quality of soapsuds with respect to color, size of the bubbles, flexibility and wetness. N-alkyl-p-alanines have been suggested as foam stabilizers. However, the presence of these alanines in alkyl benzene sulfonate detergent compositions causes a reduction in the detergent power thereof, and their application must be, therefore, ruled out.

I have now found that very satisfactory foam characteristics can be imparted to a detergent composition, in which the major active organic detergent ingredient is a watersoluble alkyl benzene sulfonate in the amount equal to from 10 to 50% by weight of the total content of solids, by introducing into such a composition a small quantity of N-alkyl imino-diacetic acid wherein the alkyl chain contains from 8 to 18 carbon atoms. Very satisfactory foams can be obtained with the aqueous solutions of detergent compositions wherein the predominant organic detergent ingredient is an alkyl benzene sulfonate, containing from 0.5 to 10% by weight of N-alkyl imino-diacetic acid additives, based on the total content of solids (or from 5 to 20% based on the weight of the active sulfonate ingredient), not only with respect to the volume and quality thereof, but also with respect to its persistence throughout the entire agitation cycle in the washing machine. The greater is the concentration of the additive in the detergent composition, the better is the foam persistence. In general, an abundant foam of good quality and a high degree of persistence can be obtained by adding to the alkyl benzene detergent composition from 2 to 4% (by weight of the total solids) of an N-alkyl imino-diacetic acid, though smaller or greater amounts may be required with varying water hardness, concentration and temperature and quantities of individual ingredients within the disclosed operative ranges thereof.

3 This additive, which for the sake of brevity, will be termed hereafter N-alkyl diglycine, is soluble. in water I and nonvolatile, both of these properties representing a decided advantage over the previously proposed additives positions containing sodium C9-C18 monoalkyl benzene sulfonate as the major organic detergent ingredient.

This sodium salt is easily prepared by a simple one-step reaction of a straight-chain Cs-Crs alkyl amine with sodium .chloroacetate. An excellent source of fatty amines for the preparation of effective N-alkyl diglycines is offered by'coconut fatty acid amines ordinarily containing about 15% of amines with less than 12 carbon atoms in the alkyl chain, about 45% of C1; amine, and about 40% of amines with more than 12 carbon atoms in the alkyl chain. I have found that while generally watersoluble alkaline salts of N-alkyl diglycines containing from Ca-Cia carbons in the alkyl chain will secure the desired improvement in the foam properties of an alkyl benzene sulfonate detergent composition, particularly satisfactory results will be obtained with water-soluble alkaline salts of N-alkyl diglycines containing from 10 to 16 carbon atoms in the alkyl chain, the best results being secured with water-soluble alkaline salts of N-alkyl diglycines containing from 12 to 14 carbon atoms in the alkyl chain.

' The N-alkyl diglycine may be introduced into the sulfonate detergent composition either before the'neutralization of the sulfonic'acid-unreacted sulfuric acid mixture or it maybe added as a corresponding water-soluble salt to the neutralized slurry, this last technique being preferred. Upon blending of the additive with the neutralized slurry, the mixture is reduced to the desired particle size and foam, e; g., by spray-drying. The N-alkyl diglycine may be also added to alkyl benzene sulfonate detergent essentially free of inorganic salts and formulated as concentrated liquids with water or other appropriate solvents.

As pointed out hereinbefore, the alkyl benzene sulfonate detergent compositions, foam properties of which can be improved by the addition of N-alkyl diglycine additives according to the invention, may contain from 10 to 50% by weight of organic detergent ingredients, at least 50% whereof is constituted by a water-soluble salt of a Gil-C18 monoalkyl benzene sulfonic acid, and preferably of a C12-C15 monoalkyl benzene sulfonic acid, and preferably of a Ora-C monoalkyl benzene sulfonic acid. The term water-soluble salt employed hereinabove includes inorganic alkaline metal salts, alkaline earth metal salts such as magnesium, ammonium salts, and organic alkyl amine and alkylol amine salts, exemplified by triethanol and diethanol amine salts. Minor amounts of anionic and non-ionic organic detergents may be present in the formulations, the foam persistence of which is improved by the addition of N-alkyl diglycines, e. g., alkyl sulfates, polyglycol ethers of alkyl phenols. Ordinarily, the alkyl benzene sulfonate detergent compositions containing an N-alkyl diglycine additive are dissolved in water to form solutions of 0.1 to

. 0.4% concentration, conventionally employed in thelaunsolid constituents thereof. have received an addition of N-alkyl diglycine in the amounts of from 0.5 to 1.0%, and, preferably from 2 to 4%, based on the weight of the total solids, the aqueous wash solutions of these heavy-duty compositions in non-automatic, agitator-type washing machines form dense, soap-like suds, which persist throughout the entire washing cycle, i. e., up to 20 minutes and often longer.

The flexible texture of the foams thus produced resembles that of the better fatty acid soaps: They are light in color, and are made up of small-size bubbles agglomerated to a cream-like consistency. In contrast to a number of other anionic detergent compositions, the

foams produced by alkyl benzene sulfonate detergent compositions improved in accordance with my invention do not buildup astifi central ring of dry and frosty foam around the agitator shaft in the tub of the washing machine. Furthermore, the presence of an N -alkyl diglycine additive imparts a slippery, soap-like feel to the wash solution, a property sought for by the housewife.

Moreover, a highly attractive characteristic of the improved detergent composition of the invention is its emollient effect upon the skin of the operator due to the presence of the N-alkyl diglycine additive. Whereas quite often housewives and laundry workers handling anionic detergent compositions complain of their drying actionwhich sequesters oil from the skin and causes cracking and fissuring thereof, this adverse action has not been observed in the numerous test runs effected with the alkyl benzene sulfonate compositions containing salts of N-alkyl diglycines in accordance with the present invention. I Several series of test runs were carried out to evaluate: the quality and persistence of foams produced byalkyl benzene sulfonate detergent compositions'containing- N alkyl diglycine additives in accordance with the invention. In a representative test series, the N-alkyl iminodiacetic acid additive (N-alkyl diglycine) was prepared as follows: 51 g. of lauryl amine, 21 g. of NaHCOz, and 25 ml. of isopropanol were placed in a 500 ml. round-bottomedflask equipped with a thermometer, stirrer and addition funnel. The mixture was heated to 150 F., whereupon a solution of 59 g. of sodium chloroacetate in 75 ml. of water was added dropwise for a period of about 15 minutes, taking care to maintain the temperature without heating at 150175 F. Upon completing the addition, the solution was refluxed for at least 3 hours until the evolution of CO2 ceased. The final solution (165 g'.) contained 'g. of N-lauryl imino-diacetic acid as the monosodium salt at pH 7.5. The sulfonate detergent composition employed in this test series contained sodium C12-C15 polypropylene benzene sulfonate (prepared by the process disclosed by A. H. Lewis in U. S. Patent'#2,477,- 383) as its sole organic detergent ingredient in an amount from 20 to 30% by weight, from 2 to 3% by weight of a N-lauryl diglycine, the remainder to make up being sodium tripolyphosphate (or a mixture of sodium tripolyphosphate and tetrasodium pyrophosphate) and sodium sulfate. The tests consisted in agitating identical loads of soiled cotton laundry in the bowl of an agitator-type non-automatic domestic washing machine filled with a dilute aqueous solution of the detergent containing an effective amount of an N-alkyl diglycine additive. Solutions of 0.15% concentration of these detergent formula-- tions in soft water (50 p. p. m.; CaCOs: MgCOa=2:1') were maintained at the same temperature throughout the test runs, and the agitation was carried out in each instance for 20 minutes under identical conditions.

The results of this series of test runs are tabulated in Table I. Persistence of the foam after 2, 5, 10, 15 and 20 minutes of operation is defined in terms of foam height (in inches) and coverage, i. e., the extent of the tub surface covered by the foam, in'per cent. The data foam persistence or none at all. On the other hand, dilute cotton towels, to each of which had been pinned a strip aqueous solutions of those detergent compositions whi h of cotton, uniformly soiled with an oily soil. In each contain the diglycine additive display excellent foam pertest run agitation was carried out for the same length of sistence; and. the foam produced by these wash solutions time and under identical conditions. After the complelasts 20 minutes and longer, without substantial reduction 5 tion of each test run, the swatches were removed, and the of volume .or alteration of foam quality, in spite of the degree of whiteness (detergency) obtainedwas measured Table I creamy dense suds, made up of small size bubbles, pro- Size of the "foambubbles, and the feehor body of the foam produced by sulfonate detergent formulations containing an N-alkyl diglycine, favorably compare with the 'duced by a 0.25%solution of aphosphate-built, tallow' fatty acid soap (run #23 of the table) and are definitely; superior to lacy, rapidly decaying foam of alkyl benzene sulfonate detergent compositions which did not contain diglyciue additives (runs#l, 3, 5;. 9 of the table).

Wetness'and mobility of the foam are likewise satisfactory: samples, placed upon a vertical glass surface, slide down rapidly as compared to several samples of foams produced by dilute solutions of commercial alkylg' sulfate-alkyl benzene sulfonate detergent compositions which appear to be dry and frosty, and cling to the glass"""' surface. I L Increasing water hardness appears to increase the foam jf persistence, and the like effect is observed on replacing sodium sulfate builder in the sulfonate detergent com-i position by magnesium sulfate, However, in either in a stance, the detergency of the wash solution isadversely] affected, and a greater concentration of the active detergent sulfonate component may be required.

At this point, it maybe noted that it is possible to com- 457/ bine with advantage into the same sulfonate detergent formulation an N-alkyl diglycine: additive which improves foam persistence and foam quality with alkylol amides off higher fatty acids, such as isopropanol amide of lauric acid or ethanol amide of lauric acid, which, in addition to being good foaming agents, tend to enhance detergency. Heretofore, it was impossible to spray-dry a' neutralized slurry of alkyl benzene sulfonate containing 25% by weight or more (based on the total solids) of the, active sulfonate detergent and as little as 2% by weight of an alkylol amide of a higher fatty acid, without running into the problems of: (1) stickiness inthe spray-drying step (the material adheres to the. walls of the spray-drying chamber instead of readily dropping into the hopper); and (2) caking upon storage of the spray-dried product. 50 For instance, the neutralized slurry containing 20%. by weight of sodium alkyl benzene sulfonate and 2% by weight of isopropanol amide of lauric acids was difficult to prayry. and pon p ng d sto ge n a humid; atmosphere'caked' badly, and failed to pass, the required specifications. On the other hand, a slurry containing 30% by weight of sodium alkyl benzene sulfonate and 3% by weight of the sodium salt of N-lauryl diglycine presented. no problem in the course of spray-drying and satisfactorily passed the caking specification after similar storage in a humid'atmosphere. Thus, by aproper selw tion of the twat-mm im roving additives (Nalkyt diglycine and-alkylol amide ofa higher fatty-acid), it will be possible to eliminate the aforementioneddifficulties of manufacturing and storage and to impart better properties.

to sulfonate detergent formulations, 'so as to make them more attractive for the consumer. 1 a

It is. to be understood that the aforegiven description and experimental data are merely illustrative of the'invention; and-that it may be modifiedwithout essential departure from the spirit and scope thereof, provided that such modifications fall within the scope of the appended claims.

Iclaim; V p

1. A- detergent composition, characterized by a high degree of persistence of its foam under conditions of agi tation in dilute aqueous. solutions, consisting essentially of from 10 to' 50% by weight, based on the total content of solids in said composition, of a water-soluble salt of a C9-C1s monoalkyl benzene sulfonic acid as its major or? ganic detergent ingredient, from 0.5 to 10% of a watersoluble salt of an N-alkyl imino-diacetic acid wherein the alkyl group. contains from 10 to. 16 carbon atoms, the

remainder-to make up being essentially inorganic salt detergent builders.

A detergent composition, characterized by a high degree of persistence of'its foam under conditions'of agitation in dilute aqueous solutions, consisting essentially of from 10 to 35% by weight, based on the total content of solids in said composition, of a water-soluble salt of a C9-Cl8 monoalkyl benzene sulfonic acid as its major organic detergent ingredient, from 2 to 4% 'of a watersoluble salt of an N-alkyl imino-diacetic acid wherein the alkyl group contains from 10 to 16 carbon atoms, and the remainder to make up 100% being essentially inorganic salt detergent builders.

3. A detergent composition, characterized by a high degreeofpersistence of its foam under conditions of agitation indilute aqueous solutions, consisting essentially of 7 -from 10 to 50% by weighhbased on the total content of V solids in said composition, of a water-soluble salt of a "Ga-Cm monoalkyl' benzene sulfonic acid as its major organic detergent ingredienh'fr'om 0.5 to 10% of a water- ,soluble salt of an N-a-lkyl' imino-diacetic acid-wherein the alkyl group contains from 10 to 16 carbon atoms, and the remainder/to make up 100%.being essentially inorganic salt detergent builders, of which from 10 to 50% is sodium sulfate. I 4. A detergent composition, characterized by a high degree of persistence of its foam under conditions of agitat-ion in dilute aqueous solutions, consisting essentially of from 10 to 50% by weight, based on the total content of solids in said composition, of a water-soluble salt of a 'Cs-C monoalkyl benzene sulfonic acid as its major organic detergent ingredient, from 0.5 to 10% of a watersoluble salt of an N-alkyl imin -diacetic acid wherein the alkyl group contains from 10 to 16 carbon atoms, from 10 to 45% of sodium sulfate builder, and the remainder to make up. 100% being essentially inorganic alkaline polyphosphate builders.

5. A detergent composition, characterized by a high degree of persistence of its foam under conditions of agitation in dilute aqueous solutions, consisting essentially from 10 to 50% by weight, based on the total content of solids, in said composition,,of"a water-soluble salt of a Cs-C1 monoalkyl benzene sulfonic acid as its major organic detergent ingredient, from 0.5 to 10% of a watersoluble salt of an N-alkylj imino-diacetic acid wherein the alkyl group contains from 10 to 16 carbon atoms, from 10 to 45% of sodium sulfate builder, and the remainder being essentially a mixture of sodium tripolyphosphate and tetrasodiurn pyrophosphate.

6. A detergent composition, characterized by a high degree, of persistence of the foam of its dilute aqueous i solutions underconditions of agitation and in the presence of soil, said composition consisting essentially ,of a'water-so'luble salt of a Cs -Cia monoalkyl benzene sulfonic acid as its major organic detergent ingredient normally tending to sequester oil from human skin and to References Cited in the file of this patent canse irritation thereof, am} from 5 to 20%, based on the UNITED STATES PATENTS weight of said sulfonlc acid salt, of a water-soluble salt of an N-alkyl imino diacetic acid, in which the alkyl 210973864 P 1937 group contains from 10 to 16 carbon atoms as a foam 5 2477383 Lewls July 1949 persistence improver and an inhibitor of skin irritation. 2619467 Isbeu 25, 1952

Claims

6. A DETERGENT COMPOSITION, CHARACTERIZED BY A HIGH DEGREE OF PERSISTENCE OF THE FOAM OF ITS DILUTE AQUEOUS SOLUTIONS UNDER CONDITIONS OF AGITATION AND IN THE PRESENCE OF SOIL, SAID COMPOSITION CONSISTING ESSENTIALLY OF A WATER-SOLUBLE SALT OF A C9-C18 MONOALKYL BENZENE SULFONIC ACID AS ITS MAJOR ORGANIC DETERGENT INGREDIENT NORMALLY TENDING TO SEQUESTER OIL FROM HUMAN SKIN AND TO CAUSE IRRITATION THEREOF, AND FROM 5 TO 20%, BASED ON THE WEIGHT OF SAID SULFONIC ACID SALT, OF A WATER-SOLUBLE SALT OF AN N-ALKYL IMINO DIACETIC ACID, IN WHICH THE ALKYL GROUP CONTAINS FROM 10 TO 16 CARBON ATOMS AS A FOAM PERSISTENCE IMPROVER AND AN INHIBITOR OF SKIN IRRITATION