Non-caking alkyl aryl sulfonate
US 2717243 A
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Unite rates 'atent 2,717,243 Sept. 36, 1955 NON-CAKIN G ALKYL ARYL SULFONATE DETERGENT COMPOSITIONS Herman S. Bloch, Chicago, and George L. Hervert,
Downers Grove, Ill., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application June 19, 1951, Serial No. 232,478
18 Claims. (Cl. 252138) This invention relates to a detergent composition in comminuted form containing a combination of ingredients including an active, water soluble, but normally hygroscopic detergent salt which in the presence of the remaining ingredients of the present composition may exhibit substantially no tendency to cake upon storage at relatively high temperatures or high atmospheric humidity. More specifically, the present invention concerns a detergent composition containing a relatively high melting point, anti-hygroscopic component in combination with an ingredient which enhances the solubility of the remaining components in aqueous solution.
The hygroscopicity of certain anionic detergents in contact with humid atmospheres which may, even at rela tive low humidities, cause the detergent to deliquesce and to subsequently cake and the low melting point of other detergents which causes a detergent composition containing the same to agglomerate into larger aggregations of particles have been common and widely recognized problems in the manufacture and sale of compositions containing such detergents. The problem is particularly manifest in packaging of commercial detergent compositions where the deliquescent property of the detergent and/or its low melting point results in the tendency of the product to clog in the packaging machines or to form a rigid cake or a mass of hard lumps in the package, the composition losing the original free-flowing characteristics of the small particles and in its lump form requiring a longer period to dissolve in water when utilized by the consumer. This tendency of the comminuted detergent composition to absorb moisture from the surrounding atmosphere or to fuse into larger agglomerates when the atmospheric temperature increases and subsequently form the undesirable aggregates of the particles thus negatives the intended effect of originally forming the composition in comminuted form to enhance the free-flowing characteristics and rapid solubility of the product in water.
One of the primary objects of this invention is to provide a comminuted detergent composition containing a highly efiective, but normally hygroscopic detergent salt,
and a component which reduces the tendency of the anionic detergent component to agglomerate into lumps or into a hard, relatively solid aggregation of detergent particles. Another object of the present invention is to provide a detergent composition which remains in freeflowing, readily water-soluble condition during storage at high temperatures or in atmospheres of relatively high humidity. Still another object of the invention isv to provide a process for intimately admixing an anti-hygroscopic agent with a normally hygroscopic anionic detergent and incorporating therein a component which promotes the water-solubility of the anti-hygroscopic agent.
In one of its embodiments, the present invention relates to a comminuted detergent composition comprising: (1) a detergent selected from the group consisting of a normally hygroscopic and the relatively low melting point alkyl aromatic sulfonate salts, (2) an alkyl aromatic sulfonate salt of a metal selected from theelements of groups 2 II and III of the periodic table, and (3) a sequestering agent for said group If and group III metal sulfonate salts.
A more specific embodiment of the invention concerns a detergent composition comprising: (1) a detergent salt selected from the group consisting of an alkali metal, an ammonium, an alkyl ammonium, and a hydroXy-alkyl ammonium salt of an alkyl benzenoid sulfonic acid, (2) from about 5 to about 50% by Weight of said composition of the magnesium salt of an alkyl benzenoid sulfonic acid, and (3) an alkali metal polyphosphate sequestering agent for said magnesium salt, said alkyl benzenoid sulfonic acid containing an alkyl substituent having from about 9 to about 18 carbon atoms per alkyl substituent.
Other objects and embodiments of the present invention relating to specific components of the detergent composition, to special methods of incorporating the antihygroscopic agent into the composition, and other factors involved in the production of the present product will be referred to in greater detail in the following further description of the invention.
The component of the present detergent composition broadly referred to herein as an anionic alkyl benzenoid sulfonate salt is a Water-soluble detergent compound which under normal conditions, in the absence of an accompany ing anti-hygroscopic agent, tends to undergo deliquescence when in contact with a humid atmosphere in storage or under other conditions normally obtaining during the manufacture or use of detergent products. The anionic detergent component is further characterized in being a member of the class of compounds which are ionically stable in aqueous solution and in the presence of alkaline earth metal ions and other heavy metal ions generally present in the so-called hard waters commonly used in domestic and industrial deterging operations. Detergents having these characteristics are usually selected from the sulfate, sulfonate and phosphonate salts prepared from synthetically produced organic charging stocks. It is thus intended to exclude such detergents as the sodium and potassium salts of long chain fatty acids known as soaps which form a water-insoluble curd when dissolved in Water containing magnesium or calcium ions in solution. Al though many anionic detergents are characterized by deliquescence and/ or low melting points, the group repre! sented by the commonly used anionic synthetic wetting agents and detergents are particularly adapted for use in the present detergent composition, including, for example, the alkyl sulfonate class of compounds, such as sodium cetylsulfonate, sodium lauryl sulfonate, etc.; the alkanol sulfate type, such as the mono-sodium salt of the sulfate esters of lauryl and cetyl alcohols; the alkylaryl sulfonates of both the monoand polynuclear aromatic hydrocarbons and their homologs, as for example, the alkali metal salts of decyl-, dodecyl-, pentadecyl-, hexadecyb, and octadecylbenzene sulfonic acids, the corresponding alkyl substituted sodium toluene sulfonate salts, sodium alkyl tetralinsulfonates, and sodium isopropylnaphthalene sulfonate, etc.; the alkali metal salts of the sulfated fatty acid monoglycerides, such as a sodium or potassium salt of the mono-glyceride esters of oleic, stearic, palmitic, and margaric acid sulfates; the alkylated phenol sulfonates, such as the sodium sulfonate salt of butylphenylphenol; the alkali metal succinate and sulfosuccinate salts, such as the alkali metal salts of dioctylsulfosuccinic acid ester; the alkyl and alkyl aromatic phosphonate salts, such as sodium lauryl phosphonate, sodium dodecylbenzene phosphonate, etc., and other anionic detergents which have relatively low melting points or which generally deliquesce in humid atmospheres. Although the potassium and sodium salts of the various organic acid radicals involved in the structure of such detergents are most widely used, the salts of ammonia, alkyl amines (Which form the corresponding alkyl ammonium salts when the amine is reacted with the organic acid radical) and the alkanol amines and polyalkanol amines (which form the corresponding hydroxyalkyl ammonium salts of the organic acid radical) may likewise be utilized in the present composition and in the case of certain preparations, such as shampoos, etc., the latter ammonium salt derivatives may be preferred.
An anionic detergent which is presently being widely used in commercial and domestic applications, particularly adaptable for use as the detergent component of the present composition, is the type known as alkyl aromatic sulfonate salts, and particularly the sodium sulfonate salts which tend to cake rapidly upon storage in bulk at high atmospheric temperatures and humidities. The most effective detergents of the alkyl aromatic sulfonate class are preferably benzenoid in structure, containing an alkyl group having from about 9 to about 18 carbon atoms per group, although the alkyl polycyclic aromatic sulfonate types containing alkyl groups having up to about 9 carbon atoms per alkyl group, such as the nonylnaphthalene sulfonate salts, the amylmethylnaphthalene sulfonate salts, etc., comprise useful detergent ingredients which may be incorporated into the present detergent composition. The long chain alkyl benzene sulfonate salts, such as sodium dodecylbenzene sulfonate generally tend to cake less readily than the corresponding monolong chain alkyl substituted toluene sulfonates because of their higher melting points and their lesser tendency to deliquesce in the presence of humid atmospheres. However, even though relatively more resistant to caking than the corresponding toluene derivative salts, the long chain alkyl benzene sulfonates exhibit marked tendencies to cake when composited with other common detergent composition ingredients such as builder salts, extenders, etc., hereinafter more specifically characterized, as compared with soaps or other anionic detergents such as, for example, sodium lauryl sulfate. Furthermore, the structure of the long chain alkyl group attached to the aromatic nucleus of the detergent molecule may have marked influence upon the hygroscopicity and melting point of the detergent. Thus, when the long chain alkyl substituent attached to the aromatic nucleus is a highly branched chain alkyl group, such as a polypropylene alkyl group, the sulfonated and neutralized product forms an especially effective detergent product, which is likely to be more deliquescent and have a lower melting point than the corresponding detergent prepared from a more relatively straight chain alkyl group on the benzenoid hydrocarbon nucleus. It is thus evident that the tendency of a given detergent composition to undergo caking at relatively high atmospheric temperature and/or humidity is dependent upon a large number of factors.
The effectiveness of the detergent component in its detersive action in an aqueous solution thereof is enhanced by compositing the same with a so-called builder salt or a mixture of several of such salts, which in themselves may be deliquescent and which generally lower the melting point of the detergent component, especially when composited in intimate admixture therewith. Suitable builder salts for this purpose may be selected from the group comprising one or a mixture of the water-soluble alkali metal, ammonium, amine, or alkanol amine sulfates, chlorides, phosphates, dihydrogen phosphates, silicates, borates, carbonates, and polyphosphates, the preferred members of this group consisting of the alkali metal sulfates, phosphates and polyphosphates. Of the latter, sodium sulfate and the sodium polyphosphates, as for example, tctrasodiump'yrophosphate or sodiumtripolyphosphate are preferred when composited with an alkyl aromatic sulfonate salt. The builder salt, when incorporated in the present detergent composition, is added thereto in amounts ranging from about 10 to about 85% by weight thereof, preferably from about to about 65% by weight of the final detergent composition. Although the presence of the builder salt is usually an aid to the detersive activity of the final composition, and may even improve the hygroscopicity of the mixture somewhat, even the least hygroscopic of the usual builder salts cannot usually by itself eliminate the problem of caking in such compositions.
The anti-caking component of. the present detergent composition, which tends to prevent caking due to its high melting point and/or its resistance to deliquesce at normal or above-normal conditions of atmospheric tempcrature and humidity is a salt selected from the class of compounds referred to as the alkyl aromatic sulfonate salts of metals selected from the elements of groups ll and III of the periodic table, particularly the salts of magnesium, calcium, strontium, barium, aluminum, and zinc. in which one or more alkyl radicals may be substituted on the aryl nucleus and in which the alkyl radicals may contain from 1 to about 18 carbon atoms per alkyl group. Of these salts, the magnesium and calcium alkyl aromatic sulfonate salts are particularly preferred because of their high order of effectiveness. The alkyl aromatic sulfonates in which a single long chain alkyl group or several shorter chain alkyl groups are substituted on the aryl nucleus are preferred anti-caking components in the present composition, due to the progressive reduction in solubility of the group II and III metal sulfonates as the chain length of the alkyl group or groups increases and as the number of such groups substituted on the aryl nucleus increases. For this reason it is also preferred that the aryl nucleus of the anti-caking component be benzenoid, rather than polycyclic, although certain members of the short chain alkyl substituted naphthalenes also form effective anti-hygroscopic agents which may be used in the present composition. The anti-caking agents herein provided, selected from the alkyl aromatic sulfonic acid salts of the metallic elements of groups II and III of the periodic table are effective in the detergent composition in amounts even as low as about 1% by weight of the final composition, although amounts as high as 50% of the composition may be used. An anticaking agent content of from about 5 to about 20% by weight of the composition is, however, preferred. In many cases the anti-caking agent may be a group II or group III metal salt of the same anion present in the alkali metal detergent salt.
The anti-caking agents of the present composition selected from the aforementioned sulfonate salts are usually relatively less soluble in aqueous solutions of the detergent than the corresponding sodium salts, although they have, in general, a fair degree of solubility. It is desirable, when a completely water-soluble detergent composition is desired, to incorporate into the detergent composition a sequestering agent which enhances the solubility of the anti-caking component in aqueous solution. An insoluble component in a detergent composition intended for laundry purposes or other uses in which a clear aqueous solution of the detergent is desirable would tend to reduce the utility and wide acceptance of the composition for detergent purposes, and it therefore becomes desirable to incorporate into the composition the present sequestering agent component in order to solubilize the anti-caking component in the detergent solution; however, where the presence of a flocculent, insoluble precipitate does not necessarily render the detergent composition ineffective or undesirable for a particular deterging operation, the sequestering agent component would not be a necessary ingredient in the present composition. Suitable organic and inorganic compounds which may be utilized in the present composition as sequestering agents include two general classes of materials: (1) the socalled versenes or sequestrenes and (2) the alkali metal polyphosphate salts which in general are characterized as the alkali metal salts of phosphoric acid from which the water of hydration has been partially removed. Typical compounds selected from the above two classes of materials include the tetra-acetate salts of ethylenediamine, the monoalkyl ethylenediamine triacetate salts,
such as the sodium salt of N-ethyl-ethylene-diarnine triacetate, the N,N-dialkyl-ethylenediamine-diacetates, sodium tetraphosphate, tetrasodium pyrop'hosphate, sodium hexametaphosphate, and sodium tripolyphosphate. Thesequestering agent is incorporated into the detergent compound in amounts representing stoichiometric proportions, based on the quantity of anti-caking component in the composition, in amounts sufficient to form a watersoluble complex with the anti-caking agent when the detergent composition is added to Water preparatory to the deterging operation. An additional quantity of sequestering agent may be added, however, to overcome the hardness of the water in which the detergent is used. Although the amount of sequestering agent in the composition required to solubilize the anti-caking component is proportional to the amount of the latter component in the composition and also proportional to the valence of the metallic salts selected for the anti-caking component, the amount is generally from about 1 to about 25 by weight of the composition, and preferably from about 5 to about by weight thereof. In the case of the polyphosphates, however, larger quantities, as much as 50% or even higher, may be incorporated, because of the excellent building qualities of such salts. For certain detergents Which deliquesce rapidly in contact with atmospheric humidity or which have relatively low melting points, larger quantities of the anti-caking component are required to prevent the undesirable caking tendency of the final composition and the amount of sequestering agent required to solubilize the anti-caking component is accordingly proportionately increased. It is generally preferable, however, to incorporate an excess of the sequestering agent in the composition in order to insure substantially complete solubilization of the anti-caking com-- ponent even in the presence of added water hardness.
In order to maintain the desired activities of the several components of the present detergent composition until the composition is used in a deterging operation, it is essential that the reaction between the anti-caking component and the sequestering agent be suspended until the detergent composition is added to water preparatory to its use in a deterging operation. it therefore becomes essential to prevent the ionic exchange between the anticaking component and the sequestering agent while the composition is in its packaged form prior to its dissolution in water. Thus, in compositing the components of the present composition the dry anti-caking component may be added to a previously dried solution or slurry formed of a mixture of the detergent and sequestering Component, or, alternatively, the dry sequestering agent may be incorporated with a previously dried mixture of the detergent and anti-caking component. Since the greatest anti-hygroscopic effect is obtained by intimately mixing the anti-caking component with the detergent component, preferably by forming an aqueous slurry of the latter two ingredients and thereafter drying the resulting slurry to an anhydrous condition, it is generally preferred to add the dry sequestering agent to a previously dried mixture of the anti-caking component and the detergent ingredient. Although aqueous slurrying of the detergent and anti-caking component is generally preferred to obtain the most intimate admixture thereof and a resulting reduced tendency to undergo caking upon storage, any other means of compositing may also be employed, as for example, by grinding the detergent and anti-caking component together in the form of a fine powder and thereafter mixing in the sequestering component, or the separate components may be mixed in dry, powdered form immediately preceding the packaging of the mixture.
In addition to the essential components of the present composition, that is, the detergent, the anti-caking component and the sequestering agent, the composition may also contain other components common to many of the conventional detergent compositions presently on the market, such as the aforementioned builder salts, water alkalizing agents such as sodium carbonate, sodium silicate, trisodium phosphate, and borax; pH-controlling agents when the alkalinity of the detergent composition is desirably reduced, such as the alkali metal salts of the lower fatty acids, including sodium acetate, sodium propionate, sodium butyrate, etc.; pigments, particularly bluings or dyes which fluoresce blue; abrasives and fillers,
such as silica, pumice, chalk, talc, Pullers earth and the like; perfumes and deodorants; germicides, such as phenol, resorcinol, mercuric chloride, phenyl mercury chloride and others; bleaching agents such as sodium hydrosulphite, ammonium thiosulphate, and others; soil suspending agents, such as sodium carboxymethyl cellulose,-
, tion, thereby forming roughly spherical particles having free-flowing characteristics when poured from their packaging containers. in accordance with this method, which may be well adapted to comminution of the present detergent composition, an aqueous suspension, slurry or solution of the detergent and the sequestering agent or the detergent and the anti-caking component is sprayed into a hot, dry atmosphere and the resulting droplets suspended therein until the Water has been evaporated therefrom, forming a dry residue of solid ingredients in roughly spherical form. In carrying out this method, in which an aqueous slurry or solution is formed prior to the spray drying, it is essential that no combination of components'be formed which is capable of reacting in the presence of water whereby the aforementioned ionic exchange reaction between the anti-caking component and the sequestering agent can take place While the com.- ponents are contacted in the presence of water. Thus, if a slurry is prepared containing the detergent and the anti caking component and the resulting slurry spray dried, the sequestering agent is added to the dried par-' ticles following the spray drying and preferably admixed therewith in powdered form. Alternatively, the anticaking component may be added in powdered form to a spray dried slurry of the detergent and the sequestering agent previously in aqueous suspension or solution. Other methods of comminution include extrusion or pelleting the dried components of the composition whereby the latter, generally in finely divided, powdered form are compressed into a confining space and thereafter ejected in the form of hard, regularly shaped particles. Suitable binding agents, such as water-soluble rosin derivatives or plasticizers may be added to the powdered components prior to the extrusion in order to form a structurally rigid particle with the added binder holding the dried particles together. Still another method of comminution is the well-known drum drying method in which an aqueous suspension of two compatible components of the composition is spread as a thin film on the surface of a rotating heated drum, the dried residue being scraped therefrom in the form of small platelets or chips. The drumdried particles may thereafter be tumbled with the remaining component of the composition, such as the anti.
caking component, in the dry state.
to the following examples which illustrate the process and composition of this invention relative to specific embodiments thereof. The examples are not intended,
however, to limit the generally broad scope of the invention as hereinabove specified.
7 EXAMPLE Aseries of detergent compositions which are normally hygroscopic and cake rapidly when exposed to atmospheric humidity, consisting of mixtures of 60% by weight of sodium sulfate and 40% by weight of the organic detergent component was prepared and various alkyl aromatic sulfonate salts of metals selected from groups II and III of the periodic table were admixed in the presence of water with the detergent-sodium sulfate mixture, forming a mixture of sodium sulfate, detergent and the alkyl aromatic sulfonate salt of a group II or group III metal. The aqueous slurry was thereafter dried on a heated rotating drum from which small detergent composition chips were scraped. The latter were subsequently composited with a dry sequestering agent and the detergency of the resulting compositions determined. The flaked, drum-dried product containing the anti-caking component, but not the sequestering agent was dried at 130 C. for ten hours for each test sample of detergent composition in order to a Table I.Adsrpti0n of moisture by detergent compositions in an atmosphere of 88% relative humidity at 25 C.
H20 Content 2?: g' Detergent Composi- Additive, Wt. Perfi time Stabiltion cent (Hrs) ity ,}1; before Facc'ent calting tor P SDBS NaiSO4 33 1 SDTS NMSO4 20 1 LS NaaSO4 50 l SDBS -NazSO4 102 3. l SDBS -NazSO4 106 3. 2 SDTS NazSO4 C 52 2. 6 SDTS -N32S04 42 2. 1
SDTS N82S04 58 2. 9
Ls NB.ZSO4 o 180 3. o SDTS NazSO4 36 1. 8 SDTS N!MSO4 92. 5 2. 8
1 Sodium dodecylbenzene sulfonate.
Sodium dodecyltoluene sulfonate.
3 Laurylsultate (sodium salt).
4 Calcium dodecylbenzene sulfonate.
5 Magnesium dodecylbenzene sulfonate. 6 Aluminum dodecylbenzene sulfonate. 1 Calcium toluene sulfonate.
5 Calcium dodecyltoluene sulfonate.
' Stoarge stability factor is a numerical value representing the relative I merits of the additive anti-caking component in preventing eaking. Its value is determined by dividing the number of hours for the composition containing the additive to cake by the number of hours for the particular composition sans the anti-coking additive. For a mixture of the detergent and sodium sulfate, the factor is necessarily 1.
The above results indicate that incorporation of an alkyl aromatic sulfonate salt of a metal selected from groups II and III of the periodic table into a normally hygroscopic detergent composition containing a detergent and a builder salt increases the time required before caking from to 50 hours to 42 to 180 hours and that the addition of a sequestering agent to the composition does not substantially alter the time before caking occurs. The above compositions into which a sequestering agent, such as sodium tripolyphosphate was incorporated were readily dissolved in water without the formation of an insoluble haze in the resulting solution. The detergency of the resulting mixtures was in each case substantially equal to or better than the compositions from which the anticaking component and the sequestering agents were absent.
We claim as our invention:
1. A comminuted detergent composition comprising a free-flowing water-soluble mixture of finely divided solid particles of: (1) an anionic detergent selected from the group consisting of the alkali metal, ammonium, alkyl ammonium and hydroxy-alkyl ammonium salts of an alkyl aromatic sulfonic acid containing an alkyl group of from about 9 to about 18 carbon atoms; (2) an alkyl benzene sulfonate salt of a metal selected from the group consisting of magnesium, calcium, strontium, barium, aluminum and zinc, the last-mentioned salt having an alkyl group of from 1 to about 18 carbon atoms and being in sufiicient amount to prevent caking of said detergent, and (3) a suificient amount of a sequestering agent to enhance the solubility of the last-mentioned sulfonate salt.
2. The composition of claim 1 further characterized in that said alkyl benzene sulfonate is an alkaline earth metal sulfonate salt.
3. The composition of claim 2 further characterized in that said alkaline earth metal salt is a calcium alkyl benzene sulfonate salt.
4. The composition of claim 2 further characterized in that said alkaline earth metal salt is a magnesium alkyl benzene sulfonate salt.
5. The composition of claim 1 further characterized in that the metal of said alkyl benzene sulfonate is aluminum.
6. The composition of claim 1 further characterized in that anionic detergent is a sodium alkylbenzene sulfonate.
7. A comminuted detergent composition comprising a free-flowing water-soluble mixture of finely divided solid particles of a sodium alkylbenzene sulfonate detergent having an alkyl group of from about 9 to about 18 carbon atoms, an alkaline earth metal sulfonate salt of an alkyl benzene sulfonic acid, the last-mentioned salt having an alkyl group of from 1 to about 18 carbon atoms and being in SUlfiClBIlt amount to prevent caking of said detergent, and a sufficient amount of a sequestering agent to enhance the solubility of said alkaline earth metal sulfonate salt.
8. The composition of claim 1 further characterized in that said anionic detergent comprises a sodium alkyltoluene sulfonate.
9. The composition of claim 1 further characterized in that said sequestering agent is an alkali metal, molecularly dehydrated complex phosphate salt.
10. The composition of claim 9 further characterized in that said complex salt is sodium tripolyphosphate.
11. The composition of claim 9 further characterized in that said complex phosphate salt is sodium hexametaphosphate.
12. The composition of claim 9 further characterized in that said complex phosphate salt is tetrasodiumpyrophosphate.
13. The composition of claim 1 containing from about 5 to about 20% by weight of said alkyl benzene sulfonate salt of a metal.
14. The composition of claim 1 containing from 1 to about 25% by weight of said sequestering agent.
15. The composition of claim 1 further characterized in that said anionic detergent comprises sodium dodecylbenzene sulfonate.
16. The composition of claim 1 further characterized in that said anionic detergent comprises sodium dodecyltoluene sulfonate.
17. The composition of claim 7 further characterized in that the first-mentioned sulfonate is sodium dodecyltoluene sulfonate.
18. The composition of claim 7 further characterized in that the first-mentioned sulfonate is sodium dodecylbenzene sulfonate.
References Cited in the file of this patent UNITED STATES PATENTS 1,956,515 Hall Apr. 24, 1934 2,283,199 Flett May 19, 1942 2,486,922 Strain Nov. 1, 1949 2,542,385 Ayo Feb. 20, 1951 2,617,772 Keenan Nov. 11, 1952