GB2289687A - Agglomerated Detergent Composition Containing High Levels Of Anionic Surfactants And Potassium Salt For Improved Solubility In Cold Temperature Laundering Sol - Google Patents

Abstract

A detergent composition in form of agglomerates contains from 1% to 50% by weight of a detersive surfactant system including by weight of the surfactant system, at least 30% of a sulfated surfactant selected from alkyl sulfates, alkyl ethoxy sulfates, secondary alkyl sulfates and mixtures thereof. The detergent includes from 2% to 25% of a potassium salt selected from the group consisting of potassium carbonate, potassium chloride, potassium sulfate and mixtures thereof. Also, the detergent composition includes at least about 1% by weight of a detergency builder to enhance cleaning. The surfactant system, potassium salt and builder are agglomerated to form detergent agglomerates which are substantially free of phosphates. The anionic surfactants in the detergent composition have significantly improved dissolution in aqueous laundering solutions, especially those kept at cold temperatures, i.e. 5 DEG C to 30 DEG C.

Description

AGGLOMERATED DETERGENT COMPOSITION CONTAINING HIGH LEVELS OF ANIONIC SURFACTANTS AND POTASSIUM SALT FOR IMPROVED SOLUBILITY IN COLD TEMPERATURE LAUNDERING SOLUTIONS Ronald A. Swift Eugene J. Pancheri FIELD OF THE INVENTION The present invention is generally directed to an agglomerated compact detergent composition having improved solubility in cold temperature laundering solutions.More particularly, the invention is directed to a detergent composition containing high levels of a sulfated surfactant selected from the group consisting of alkyl sulfates (also referenced herein as "AS"), alkyl ethoxy sulfates (also referenced herein as "AES"), and secondary alkyl sulfates (also referenced herein as "SAS") and mixtures thereof, and a potassium salt selected from the group consisting of potassium carbonate, potassium chloride, potassium sulfate and mixtures thereof, together which improve solubility in cold temperature washing solutions (e.g. 5"C to 30"C) and high water hardness conditions (e.g. 7 grains/gallon).For purposes of producing a high density, compact detergent composition, the detergent of the invention is in the form of detergent agglomerates rather than spray dried granules.

BACKGROUND OF ThE INVENTION Typically, conventional detergent compositions contain mixtures of various surfactants in order to remove a wide variety of soils and stains from surfaces. For example, various anionic surfactants, especially the alkyl benzene sulfonates, are useful for removing particulate soils, and various nonionic surfactants, such as the alkyl ethoxylates and alkylphenol ethoxylates, are useful for removing greasy soils.

While the art is replete with a wide variety of surfactants for those skilled in the art of detergent formulation, most of the available surfactants are specialty chemicals which are not suitable for routine use in low cost items such as home laundering compositions. The fact remains that many homeuse laundry detergents still comprise one or more of the conventional alkyl benzene sulfonates or primary alkyl sulfate surfactants. Another class of surfactants which has found use in various compositions where emulsification is desired comprises the secondary alkyl sulfates. The conventionalSsecondary alkyl sulfate surfactants are available as generally pasty, random mixtures of sulfate linear and/or partially branched alkanes.

For example, Rossall et al, U.S. Patent No. 4,235,752, disclose a detergent surfactant which is a C10.18 secondary alkyl sulfate containing 50% of 2/3 sulfate isomers and 40% of various other effective isomers. The surfactant materials disclosed by Rossall et al are for use primarily in dishwashing operations. Such materials have not come into widespread use in laundry detergents, since they do not offer any advantages over alkyl benzene sulfonates, especially with respect to water solubility which facilitates production of high-surfactant granular detergents. Accordingly, Rossall et al do not provide a high density laundry detergent having improved solubility in either cold temperature wash solutions or high hardness water conditions.

The limited solubility of alkyl sulfate surfactants including both primary and secondary alkyl sulfates is especially prevalent in modern granular laundry detergents which are typically used in cold temperature (e.g. 5"C to 30"C) washing solutions and are formulated in "condensed" or "compact form for low dosage usage. For the consumer, the smaller package size attendant with compact detergent products provides for easy storage and handling. For the manufacturer, unit storage costs, shipping costs and packaging costs are lowered.

The manufacture of acceptable compact or condensed granular detergents has its difficulties. In a typical compact detergent formulation, the sozcalled "intro" ingredients such as sodium sulfate are substantially eliminated. However, such ingredients do play a role in enhancing solubility of conventional detergents. As a consequence, compact detergents often suffer from solubility problems, especially in cold temperature laundering solutions. Moreover, conventional compact or low density detergent granules are usually prepared by spray drying processes which result in extremely porous detergent particles that are quite amenable to being dissolved in aqueous washing solutions.By contrast, compact detergents are typically comprised of less porous, high density detergent particles which are less soluble, e.g. agglomerates. Thus, since the compact form of granular detergents typically comprise particles or granules which contain high levels of detersive ingredients with little or no room for solubilizing agents, and since such particles are intentionally manufactund at high bulk densities, the net result can be a substantial problem with regard to inuse solubility.

In the art of detergency, potassium salts has been to some extent used for purposes of improving solubility of spray dried granular detergents. For example, Boucher et al, U.S. Patent No. 5,180,515 (P & ) is directed to a granular detergent composition containing low levels of potassium salt to provide improved solubility. More particularly, Boucher et al discloses a "spray dried" granular detergent composition comprising a detersive surfactant, phosphate, sodium csbonate and potassium salt Consequently, the detergent compositions taught by Boucher et al are spray dried detergents which contain phosphates and any number of surfactants within broad amounts and proportions. The Boucher et al compositions are in the form of spray dried granules and thus do not experience the solubility problems associated with agglomerated detergents.

Further, Boucher et al employ phosphates to enhance solubility and serve as a detergency builder.

However, such phosphates have been linked to undesirable eutrophication of surface waters and therefore pose an environmental concern. Thus, it would be desirable to have a detergent composition which is devoid of phosphates and. yet exhibit improved water solubility especially under cold temperature conditions.

Accordingly, despite the disclosures in the art, there remains a need for a detergent composition which has improved water solubility, especially in cold temperature washing solutions.

Also, there is a need for such a detergent composition which is devoid of phosphates. This need is especially prevalent in the art of compact or high density detergents currently being used by consumers.

SUMMARY OF THE INVENTION The present invention meets the needs identified above by providing a detergent composition in the form of agglomerates which exhibit improved solubility or dissolution of the anionic surfactants in cold temperature washing solutions as well as under high water hardness conditions. The detergent composition comprises a surfactant system having a high level of a sulfated surfactant selected from the group of alkyl sulfates, alkyl ethoxy sulfates, secondary alkyl sulfates and mixtures thereof, in combination with a potassium salt selected from the group consisting of potassium carbonate, potassium chloride, potassium sulfate and mixtures thereof.

Other adjunct detergent ingredients may also be included in the detergent agglomerates which form the detergent composition. For purposes of enhancing environmental safety, the detergent composition does not contain any phosphates and, yet unexpectedly exhibits improved water solubility. Additionally, the composition surprisingly exhibits improved water solubility despite being in the form of high density agglomerates and being subjected to cold temperature washing solutions.

As used herein the phrase "improved solubility means that the solubility of the anionic surfactants of the detergent composition is enhanced by at least 5% in the laundering solution when employed in the manner of this invention, as compared to the solubility of the same anionic surfactants per se, under the same test conditions (i.e. water temperature and pH, stirring speed and time, particle size, water hardness, and the like). As used herein, the term "agglomerates" refers to particles formed by agglomerating particles which typically have a smaller mean particle size than the formed agglomerates. All percentages, ratios and proportions used herein are by weight, unless otherwise specified. All documents including patents and publications cited herein are incorporated herein by reference.

In accordance with one aspect of the invention, a detergent composition in the form of - is provided herein. The detergent composition comprises from about 1% to 50% by weight of a detersive surfactant system. The surfactant system itself comprises, by weight of the surfactant system, at least about 30 /e of a sulfate surfactant selected from the group consisting of alkyl sulfates, alkyl ethoxy sulfates, secondary alkyl sulfates and mixtures thereof. The detergent composition includes from about 2% to about 25% of a potassium salt selected from the group consisting of potassium carbonate, potassium chloride, potassium sulfate and mixtures thereof. Also, the detergent composition includes at least about 1% by weight of a detergency builder to enhance cleaning.The surfactant system.

potassium salt, and builder are agglomerated to form detergent agglomerates which are substantially free of phosphates. The anionic surfactants in the detergent composition have improved solubility in an aqueous laundering solution. Thus, the solubility of the sulfate surfactant (AS, AES and/or SAS) is enhanced by at least 5%, preferably 10 to 50%. over those same surfactants aloneunder the same test conditions in aqueous washing solutions at cold temperatures, i.e. 5"C to 30"C.

In accordance with another aspect of the invention, a method for laundering soiled fabrics is provided. The method comprises the step of contacting soiled fabrics with an effective amount of a detergent composition as described herein in an aqueous laundering solution. An effective amount is typically on the order of 1000 to 1500 ppm. Yet another embodiment of the invention is directed to a laundry bar formed from the instant application.

Accordingly, it is an object of the present invention to provide a granular detergent composition which has improved solubility, especially in cold temperature washing solutions. It is also an object of the invention to provide such a detergent composition which has improved biodegradabili9. These and other objects, features and attendant advantages of the present invention will become apparent to those skilled in the art from a reading ofthe following detailed description of the preferred embodiment and the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The invention is directed to a granular detergent composition having improved solubility in cold temperature laundering solutions. A multitude of consumers around the world launder soiled clothes in conventional washing machines unique to their particular geographic location. Typically, these conventional washing machines launder the soiled clothes in water supplied at relatively cold temperatures, for example in range of JOC to 300C, and at high hardness concenuations, e.g. 7 grains/gallon (rich with Ca and Mg ions). Most of the modem day consumers also use compact or condensed laundry detergents to accomplish their laundering needs. Under the aforementioned conditions, solubility of current detergents in aqueous laundering solutions has been a problem.

This problem is especially exacerbated when the detergent composition has high levels of alkyl splint, alkyl ethoxy sulfate andlor secondary alkyl sulfates which are not particularly amenable to dissolution in cold aqueous laundering solutions. Such surfactants are particularly useful in modem laundry detergents since they minimize or eliminate the need for linear alkylbenzene sulfate surlictants which generally have poor biodegradability. Moreover, recent compact detergents have salved to limit or eliminate the use of phosphates which are known to increase water solubility. In view of this trend, the water solubility problem is exacerbated further.

It has been found that the solubility of a nil-phosphate, high-content alkyl sulfate, alkyl ethoxy sulfate andlor secondary alkyl sulfate ("sulfated" surfactant system) compact detergent composition in the form of agglomerates can be increased by incorporating a potassium salt selected from the group consisting of potassium carbonate. potassium chloride, potassium sulfate and mixtures thereof. To that end. the preferred detergent composition of the invention comprises from about 2% to about 25% preferably from about 3% to about 10%, by weight of a potassium salt. The most preferred potassium salt is potassium carbonate.The surfactant system of the detergent composition comprises at least 30 /O, preferably from about 35% to about 90 /O, of a sulfated surfactant selected from the group consisting of alkyl sulfates, alkyl ethoxy sulfates, secondary alkyl sulfates and mixtures thereof. Preferably, the detergent composition is in the form of agglomerates and has an overall density of 650 gll or higher. These features provide the "compact" nature of the detergent composition in accordance with the invention. It has been found that such a detergent composition containing agglomerates having the aforementioned surfactant system and potassium salt surprisingly has significantly improved solubility in cold temperature (50C to 300C) washing solutions as well as under high water hardness conditions.

Preferably, the detergent composition of the invention also comprises at least about 1%, preferably from about 10% to about 40%, and most preferably from about 15% to 35%, of a detergency builder. The detergent composition may also include one or more of adjunct detergent ingredients. Nonlimiting examples of the detergency builder and such adjunct ingredients are described in detail hereinafter.

For purposes of enhancing biodegradability, the detergent agglomerates which form the detergent composition of the invention preferably do not contain phosphates. Further, it is important for the detergent composition to be in the form of "agglomerates" as opposed to spray dried granules. This is particularly important since most sulfated surfactants cannot be readily subjected to spray drying processes without causing or creating extremely adverse plumes from the spray drying towers.

The "improved solubility" achieved by the detergent composition is concerned with enhanced solubility of the anionic surfactants contained in the surfactant system, i.e. AS, AES, SAS or LAS if wd. Preferably, the improvement represents at least a 5% increase insolubility of these anionics in the wash solution over the solubility of the same surfactants if they were dissolved alone or without being contained in a detergent composition as defined herein. More preferably, the solubility improvement is from about 10% to about 50%. As those skilled in the art will appreciate, any comparison of anionic surfactant solubility should be completed under the same laundering conditions, e.g. water temperature, hardness and pH, stirring speed and time, and particle size.

Typical anionic surfactant solubility improvements are set forth in the Examples hereinafter.

Those skilled in the art should also appreciate the numerous ways in which the amount of the surfactant system in the washing solution can be determined. For example, in the so called "catS03" titration technique, samples of the aqueous laundering solution containing the detergent composition can be taken after one minute and filtered with 0.45 mm nylon filter HPLC, after which the filtered solution can be tiuated with a cationic titrant, which can be commercially purchased.

e.g. from Sigma Chemical Company under the trade name Hyamine. in the presence of anionic dyes. From the foregoing, the amount of anionic surfactant which was dissolved in the washing solution can be determined.

Surfactant Svstem The surfactant system in the detergent composition must include a sulfates surfactant selected from the group consisting of alkyl sulfates, alkyl ethoxy sulfates. secondary alkyl sulfates, and mixtures thereof. As men:ioned previously, the anionic surfactants in the surfactant system of the invention, i.e. AS, AES, andlor SAS, have improved solubility and more particularly, on the order of 5% or higher. Optionally, the surfactant system may contain one or more of additional surfactants, nonlimiting examples of which are provided hereinafter.

The surfactant system preferably includes conventional primary alkyl sulfate surfactants have the general formula ROSO3-Mf wherein R is typically a linear C10-C20 hydrocarbyl group and M is a water-solubilizing cation.

Branched-chain primary alkyl sulfate surfactants (i.e., branched-chain "PAS") having 10-20 carbon atoms can also be used herein; see, for example. European Patent Application 439,316, Smith et al, filed 21.01.91, the disclosure of which is incorporated herein by reference (Included in the term "alkyl" is the alkyl portion of acyl groups). Included in the surfactant system are the C10-Cl8 alkyl alkoxy sulfates ("AEXS"; especially EO 1-7 ethoxy sulfates).

Conventional secondary alkyl sulfate surfactants can also be used herein and include those materials which have the sulfate moicty distributed randomly along the hydrocarbyl "backbone" of the molecule. Such materials may be depicted by the structure CII3 (CH2)n(CHOS03 'M(CH2)mCH3 wherein m and n are integers of 2 or greater and the sum of m + n is typically about 9 to 17, and M is a water-solubilizing cation.

More preferably, a selected secondary (2,3) alkyl sulfate surfactant is used herein which comprises structures of formulas A and B (A) CH3(CH2)X(CHOSO3-M+) CH3 and (B) CH3(CH2)y(CHOS03~M+)CHoCH3 for the 2 sulfate and 3-sulfate. respectively. Mixtures of the 2- and 3-sulfate can be used herein. In fonnulas A and B, x and (y+l) are. respectively, integers of at least about 6, and can range from about 7 to about 20, preferably about 10 to about 16. M is a cation, such as an alkali metal, ammonium, alkanolammonium, alkaline earth metal, or the like. Sodium is typical for use as M to prepare the water-soluble (2,3) alkyl sulfates. but cthanolammonium, diethanolammonium, triethanolammonium, potassium, ammonium. and the like, can also be used. It is preferred that the secondary (2,3) alkyl sulfates be substantially free (i.e.. contain less than about 20%, more preferably less than about 10%. most preferably less than about 5%) of such random secondary alkyl sullies.

The preparation of the secondary (2.3) alkyl sulfates of the type useful herein can be carried out by the addition of H2SO4 to olefins. A npical synthesis using or-olefins and sulfuric acid is disclosed in U.S. Patent 3,234,258, Morris, or in U.S. Patent 5,075,041, Lutz, granted December 24, 1991, both of which are incorporated herein by reference.The synthesis, conducted in solvents which afford the secondary (2,3) alkyl sulfates on cooling, yields products which, when purified to remove the unreacted materials. randomly sulfated materials, unsulfated by-products such as C10 and higher alcohols, secondary olefin sulfonates, and the like, are typically 90+% pure mixtures of 2- and 3-sulfated materials (up to 10% sodium sulfate is typically present) and are white, non-tacky, apparently crystalline, solids. Some 2,3-disulfates may also be present, but generally comprise no more than 5% of the mixture of secondary (2,3) alkyl mono-sulfates. Such materials are available as under the name "DAN", e.g., "DAN 200" from Shell Oil Company.

If increased solubility of the "crystalline" secondary (2,3) alkyl sulfate surfactants is desired, the formulator may wish to employ mixtures of such surfactants having a mixture of alkyl chain lengths. Thus, a mixture of C12"C18 alkyl chains will provide an increase insolubility over a secondary (2,3) alkyl sulfate wherein the alkyl chain is, say, entirely C16. The solubility of the secondary (2,3) alkyl sulfates can also be enhanced by the addition thereto of other surfactants such as the material which decreases the crystallinity of the secondary (2,3) alkyl sulfatts. Such crystallinity-intcmrpting materials are typically effective at levels of 20%. or less, of the secondary (2,3) alkyl sulfate.

Potassium Salt The granular detergent composition of the present invention preferably includes from about 2% to about 250/s more preferably from about 3% to about 10% and most preferably from about 3% to S@/. of of a potassium salL It has been found that the inclusion of a potassium salt into an "agglomerated" detergent composition as described herein surprisingly aides in solubilization of a detergent which is rich in sulfated surfactants (i.e. > 30% of the surfactant system) and devoid of phosphates. In the past, potassium salts have been used to increase the solubility of "spray dried" detergents typically containing phosphates.The potassium salt regardless of form (i.e. solid, liquid or paste) is mixed with the surfactant paste prior to. or during the agglomeration step. Those skilled in the art will appreciate the wide variety of potassium salts useful for the instant detergent composition. As mentioned previously, however, the potasium salt used herein is preferably selected from the group consisting of potassium carbonate, potassium chloride, potassium sulfate and mixhucsthenof. The most preferred potassium salt is potassium carbonate.

Builder The detergent composition of the invention also includes a detergency builder material to assist in controlling mineral hardness. Inorganic as well as organic builders can be used. Builders are typically used in fabric laundering compositions to assist in the removal of particulate soils.

Inorganic detergent builders include, but are not limited to, the alkali metal, ammonium and alkanolammonium salts of phytic acid, silicates. carbonates (including bicarbonates and sesquicarbonates), sulphates, and aluminosilicates.

Examples of silicate builders are the alkali metal silicates. particularly those having a SiO2:Na2O ratio in the range 1.6:1 to 3.2:1 and layered silicates, such as the layered sodium silicates described in U.S. Patent 4,664,839. issued May 12, 1987 to H. P. Rieck. NaSKS-6 is the trademark for a crystalline layered silicate marketed by Hoechst (commonly abbreviated herein as "SKS-6"). Unlike zeolite builders, the Na SKS-6 silicate builder does not contain aluminum.

NaSKS6 has the delta-Na2SiO5 morphology form of layered silicate. It can be prepared by methods such as those described in German DE-A-3,417,649 and DE-A-3,742,043. SKS-6 is a highly preferred layered silicate for use herein, but other such layered silicates, such as those having the general formula NaMSixO2x+l yH2O wherein M is sodium or hydrogen, x is a number from 1.9 to 4, preferably 2, and y is a number from 0 to 20, preferably 0 can be used herein. Various other layered silicates from Hoechst include NaSKS-5, NaSKS-7 and NaSKS-1 1, as the alpha, beta and gamma forms. As noted above, the delta-Na2SiOs (NaSKS-6 form) is most preferred for use herein.Other silicates may also be useful such as for example magnesium silicate, which can serve as a crisping agent in granular formulations, as a stabilizing agent for oxygen bleaches, and as a component of suds control systems.

Examples of carbonate builders are the alkaline earth and alkali metal carbonates as disclosed in German Patent Application No. 2,321,001 published on November 15, 1973.

Aluminosilicate builders are useful in the present invention Aluminosilicate builders are of great importance in most currently marketed heavy duty granular detergent compositions, and can also be a significant builder ingredient in liquid detergent formulations. Aluminosilicate builders include those having the empirical formula: Mz(zAI02)yi xH2O wherein z andy are integers of at least 6, the molar ratio ofz toy is in the range from 1.0 to about 0.5, and x is an integer from about 15 to about 264.

Useful aluminosilicate ion exchange materials are commercially available. These aluminosilicates can be crystalline or amorphous in structure and can be naturally-occurring aluminosilicates or synthetically derived. A method for producing aluminosilicate ion exchange materials is disclosed in U.S. Patent 3,985,669, Kummel, et al, issued October 12, 1976. Preferred synthetic crystalline aluminosilicate ion exchange materials useful herein are available under the designations2tolite A, Zeolite P (B), Zeolite MAP and Zeolite X In an especially preferred embodiment, the crystalline aluminosilicate ion exchange material has the formula: Na12i(AlO2) 12(SiO2) 12j.2O wherein x is from about 20 to about 30. especially about 27. This material is known as Zeolite A.

Dehydrated zeolites (x = 0 - 10) may also be used herein. Preferably, the aluminosilicate has a particle size of about 0.1-10 microns in diameter.

Organic detergent builders suitable for the purposes of the present invention include, but are not restricted to, a wide variety of polycarboxylate compounds. As used herein, Xpoly- carboxylate" refers to compounds having a plurality of carboxylate groups. preferably at least 3 carboxylates. Polycarboxylate builder can generally be added to the composition in acid form, but can also be added in the form of a neutralized salt. When utilized in salt form, alkali metals, such as sodium, potassium, and lithium, or alkanolammonium salts are preferred.

Included among the polycarboxylate builders are a variety of categories of useful materials.

One important category of polycarboxylate builders encompasses the ether polycarboxylates, including oxydisuccinate, as disclosed in Berg, U.S. Patent 3,128,287, issued April 7, 1964, and Tmnherti et al, U.S. Patent 3,635,830, issued January 18, 1972. See also "TMSI'DS" builders of U.S. Patent 4,663,071, issued to Bush et al, on May 5, 1987. Suitable ether polycarboxylates also include cyclic compounds, particularly alicyclic compounds, such as those described in U.S. Patents 3,923,679; 3,835,163; 4,158,635; 4,120,874 and 4,102,903.

Other useful detergency builders include the ether hydroxypolyzarboxylates, copolymers of maleic anhydride with ethylene or vinyl methyl ether, 1, 3, 5-trihydroxy benzene-2, 4, 6trisulphonic acid, and carboxymethyloxysuccinic acid, the various alkali metal, ammonium and substituted ammonium salts of polyacetic acids such as ethylenediamine tetmacetic acid and nitrilotriacetic acid, as well as polycarboxylates such as mellitic acid, succinic acid, oxydisucctnic acid, polymaleic acid, benzene 1,3,5-tricarboxylic acid, carboxymethyloxysuccnic acid, and soluble salts thereof.

Citrate builders, e.g., citric acid and soluble salts thereof (particularly sodium salt), are polycarboxylate builders of particular importance for heavy duty liquid detergent formulations due to their availability from renewable resources and their biodegradability. Citrates can also be used, however, in granular compositions, especially in combination with zeolite and/or layered silicate builders. Oxydisuccinates are also especially useful in such compositions and combinations.

Also suitable in the detergent compositions of the present invention are the 3,3-dicarboxy 4-oxa 1,6-hexanedioates and the related compounds disclosed in U.S. Patent 4,566,984, Bush, issued January 28, 1986. Useful succinic acid builders include the C5-C20 alkyl and alkenyl sucinic acids and salts thereof. A particularly preferred compound of this type is dodecenylsuccinic acid. Specific examples of succinate builders include: laurylsuccinate, myristylsuccinate, paluutylsuccinate, 2-dodecenylsuccinate (preferred), 2-pentadeccnylsuccinate, and the like.

Laurylsuccinates are the preferred builders of this group, and are described in European Patent Application 86200690.5/0,200,263. published November 5, 1986. Other suitable polycarboxylates are disclosed in U.S. Patent 4,144,226, Crutchfield et al, issued March 13, 1979 and in U.S. Patent 3,308,067, Diehl, issued March 7, 1967. See also Diehl U.S. Patent 3,723,322.

Fatty acids, e.g., C12-C18 monocarboxylic acids, can also be incorporated into the compositions alone, or in combination with the aforesaid builders, especially citrate and/or the succinate builders, to provide additional builder activity. Such use of fatty acids will generally result in a diminution of sudsing, which should be taken into account by the formulator.

Adiunct Surfactants One or more adjunct surfactants may be included generally at a level of from about 1% to about 50% of the surfactant system described herein. Nonlimiting examples of surfactants usefiil in conjunction with the surfactants described herein are the C10-C18 alkyl alkoxy carboxylates (especially the EO 1-5 ethoxycarboxylates), the C10-18 glycerol ethers, the C10-Cl8 alkyl polyglycosides and their corresponding sulfate polyglycosides. and C12-C18 alpha-sulfonated fatty acid esters.If desired, the conventional nonionic and amphoteric surfactants such as the C12-C18 alkyl ethoxylates ("AE") including the so-called narrow peaked alkyl ethoxylates and C6-C12 alkyl phenol allcoxylates (especially ethoxylates and mixed ethoxyipropoxy), C12-C18 betaines and sulfobetaines ("sultaines"), can also be included in the overall compositions. The C10-Cl8 N-alkyl polyhydroxy fatty acid amides can also be used. Typical examples include the C12-Cl8 N methylglucamides. See WO 9,206,154. The N-propyl through N-hexyl C12-Cl8 glucamides can be used for low sudsing. C10-C20 conventional soaps may also be used. If high sudsing is desired, the branched-chain C10-C16 soaps may be used.

Also included in the surfactant system is the conventional C1 1-C18 alkyl benzene sulfonates (also referenced herein as "LAS). While the biodegradability of the so-called "LAS" surfactants have been the subject of some concern, the surfactant system herein may include an optimum level, from about 0.1% to about 15% and more preferably from about 3% to about 8% by weight, for improving the overall solubility of the detergent composition without substantially decreasing the overall biodegradability of the present detergent composition. Alternatively, the level of LAS may be included as from about 1% to about 40 /e, more preferably from about 10% to about 250/4 by weight of the surfactant system in the detergent composition.

The surfactant system may also include an amine oxide surfactant Nonlimiting examples include C10-18 amine oxides, secondary amine oxides such as dimethyl amine oxide, and tertiary amine oxides having the general formula RR'R"NO in which R is a primary alkyl group containing 8 to 24 carbon atoms; R' is methyl, ethyl, or 2-hydroxyethyl: and R" is independently selected from methyl, ethyl, 2-hydroxyethly and primary alkyl groups containing 8 to 24 carbon atoms.

Additionally, the tertiary amine oxide surfactant may be in hydrated form and have the general formula RR'R"NO nH20 wherein R R' and R" are the same as above and n is 1 or 2. Examples of other tertiaryamines suitable for use herein include those containing one or two shortchain groups independently selected from methyl, ethyl, and 2-hydroxyethyl groups, with the remaining valences of the amino nitrogen being satisfied with long-chain groups independently selected from primary alkyl groups containing 8-24 carbons, e.g., octyl, decyl. dodecyl, teuadecyl, hexadecyl, octadecyl, eicosyl, docosyl, and tetracosyl groups. The primary alkyl groups may be branched-chain groups, but the preferred amines are those in which at least most of the primary alkyl groups have a straight chain.

Exemplary of these tert-amines are N octyldimethylamine, N,N-didecylmethylamine, Ndecyl-N-dodecylethylamine, N-dodecyldimethylamine. N-tetradecyldimethylamine, N-tetradecyl-N ethylmethylamine, N-tetradecyl-N-ethyl-2-hydroxyethylamine, N,N-di-tetradecyl-2hydroxyethylamine, N-hexadecyldimethylamine, N-hexadecyldi-2- hdroxyethylamine N octatlecyldimethylamine, N,N-dieicosylethylamine, N-docosyl-N-2-hydroxyethylmethylamine, Nteuacosyldimethylamine, etc.

Additional amine oxide surfactants and methods of making the same, all of which are suitable for use herein, are disclosed by Borland et al, U.S. Patent No. 5,071,594 and Tosaka et al, U.S. Patent No. 5,096,621, incorporated herein by reference.

Mixtures of anionic and nonionic surfactants are especially useful. Other conventional useful surfactants are listed in standard texts.

Deterrent Adiunct Ingredients The detergent composition can also include any number of additional ingredients. These include detergency builders. bleaches, bleach activators, suds boosters or suds suppressers, anti-tarnish and anticorrosion agents, soil suspending agents, soil release agents, germicides, pH adjusting agents, non-builder alkalinity sources, chelating agents, smectite clays, enzymes, enzymcstabilizing agents and perfumes. See U.S. Patent 3,936,537, issued February 3, 1976 to Baskcrville, Jr. ct al., incorporated herein by reference. Also, fabric conditioning agents may be included as an adjunct material such as those described in U.S. Patent 4,861,502, issued August 29, 1989 to Caswell, incorporated herein by reference.

Bleaching agents and activators are described in U.S. Patent 4,412,934, Chung et al., issued November 1, 1983, and in U.S. Patent 4,483,781, Hanman, issued November 20, 1984, both of which are incorporated herein by reference. Chelating agents are also described in U.S. Patent 4,663,071, Bush et al., from Column 17, line 54 through Column 18, line 68, incorporated herein by reference.

Suds modifiers are also optional ingredients and are described in U.S. Patents 3,933,672, issued January 20, 1976 to Bartoletta et al., and 4, 136.045. issued January 23, 1979 to Gault et al., both incorporated herein by reference.

Suitable smectite clays for use herein are described in U.S. Patent 4,762,645, Tucker et al, issued August 9, 1988, Column 6, line 3 through Column 7, line 24, incorporated herein by reference.

Suitable additional detergency builders for use herein are enumerated in the Baskerville patent, Column 13, line 54 through Column 16, line 16, and in U.S. Patent 4,663.071, Bush et al, issued May 5, 1987.

both incorporated herein by reference.

Enzymes can be included in the formulations herein for a wide variety offabric laundering purposes, including removal of protein-based. carbohydratewbased, or triglyceride-based stains, for example, and for the prevention of refugee dye transfer, and for fabric restoration. The enzymes to be incorporated include proteases, amylases. lipases, cellulases. and peroxidases, as well as mixtures thereof. Other types of enzymes may also be included. They may be of any suitable origin, such as vegetable, animal, bacterial, fungal and yeast origin. However, their choice is governed by several factors such as pH-activity and/or stability optima. therniostability, stability versus active detergents, builders and so on.In this respect bacterial or fungal enzymes are preferred, such as bacterial amylases and proteases, and final cellulases.

Suitable examples of proteases are the subtilisms which are obtained from particular strains of B. subti Jis and B.lichenifonns. Another suitable protease is obtained from a strain of Bacillus, having maximum activity throughout the pH range of 8-12, developed and sold by Novo Industries A/S under the registered trade name ESPERASE. The preparation of this enzyme and analogous enzymes is described in British Patent Specification No. 1,243,784 of Novo. Proteolytic enzymes suitable for removing protein-based stains that are commercially available include those sold under the trade names ALCALASE and SAVINASE by Novo Industries A/S (Denmark) and MAXATASE by International Bio-Synthetics, Inc. (The Netherlands).Other proteases include Protease A (see European Patent Application 130,756, published January 9, 1985) and Protease B (see European Patent Application Serial No. 87303761.8, filed April 28, 1987, and European Patent Application 130,756, Bott et al, published January 9, 1985).

Amylases include, for example, or-amylases described in British Patent Specification No.

1,296,839 (Novo), RAPIDASE, International Bio-Synthetics, Inc. and TERMAMYL, Novo Industries..

The cellulose usable in the present invention include both bacterial or fungal cellulase.

Preferably, they will have a pH optimum of between 5 and 9.5. Suitable cellulases are disclosed in U.S. Patent 4,435,307, Barbesgoard et al, issued March 6, 1984. which discloses fungal cellulase produced from Humicola insolens and Humicola strain DSM1800 or a cellulase 212-producing fungus belonging to the genus Aeromonas, and cellulase extracted from the hepatopancreas of a marine mollusk (Dolabella Auricula Solander). suitable cellulases are also disclosed in GB-A2.075.028; GB-A-2.095.275 and DE-OS-2.247.832.

Suitable lipase enzymes for detergent usage include those produced by microorganisms of the Pseudomonas group, such as Pseudomonas stutzen ATCC 19.154, as disclosed in British Patent 1,372,034. See also lipases in Japanese Patent Application 53,20487, laid open to public inspection on February 24, 1978. This lipase is available from Amano Pharmaceutical Co. Ltd., Nagoya, Japan. under the trade name Lipase P "Amano." hereinafter referred to as "Amano-P." Other commercial lipases include Amano-CES, lipases ex Chromobacterviscosum, e.g. Chromobacter viscosum var. lipolyticum NRRLB 3673, commercially available from Toyo Jou, Co., Tagata, Japan; and further Chromobacter viscosum lipases from U.S. Biochemical Corp., U.S.A. and Disoynth Co., The Netherlands, and lipases ex Pseudomonas gladioli. The LIPOLASE enzyme derived from Humicola lanuginosa and commercially available from Novo (see also EPO 341,947) is a preferred lipase for use herein.

Peroxidase enzymes are used in combination with oxygen sources, e.g., percarbonate, perborate, pefiuifate, hydrogen peroxide, etc. They are used for "solution bleaching," i.e. to prevent transfer of dyes or pigments removed from subsuates during wash operations to other substrates in the wash solution. Peroxidase enzymes are known in the art, and include, for example, horseradish peroxidase, ligninase, and haloperoxidase such as chloro- and bromo-peroxidase. Peroxidase containing detergent compositions are disclosed, for example, in PCT International Application WO 89/099813, published October 19, 1989, by O. Kirk, assigned to Novo Industries A/S.

A wide range of enzyme materials and means for their incorporation into synthetic detergent compositions are also disclosed in U.S. Patent 3,553,139, issued January 5, 1971 to McCarty et al. Enzymes are further disclosed in U.S. Patent 4,101,457, Place et al, issued July 18, 1978, and in U.S. Patent 4,507,219, Hughes, issued March 26, 1985, both. Enyme materials useful for liquid detergent formulations, and their incorporation into such formulations, are disclosed in U.S. Patent 4,261,868, Hora et al, issued April 14, 1981. Enymes for use in detergents can be stabilized by various techniques. Enzyme stabilization techniques are disclosed and exemplified in U.S.Patent 3,600,319, issued August 17, 1971 to Gedge, et al, and European Patent Application Publication No. 0 199 405, Application No. 86200586.5, published October 29, 1986, Venegas.

Enzyme stabilization systems are also described, for example, in U.S. Patent 3,519,570.

Additionally, dye transfer inhibiting agents may also be included, for example, polyvinylpyrrolidone, polyamine N-oxide, copolymers of N-vinylpyrrolidone and N-vinylimidazole are a suitable dye transfer inhibiting polymers for use in the present detergent composition. The level of such additional dye transfer inhibiting agents may vary, but typically will be from about 0.01% to about 10% by weight of the detergent composition.

Aittlomeration Process The following describes and exemplifies the agglomeration process by which the detergent composition of the invention is produced. The parameters noted herein are exemplary only and should not be considered as limiting in any way.

Step A - Preparation of Surfactant Paste - The objective is to combine the surfactants and liquid in the compositions into a common mix in order to aid in surfactant solubilization and agglomeration. In this Step, the surfactants and other liquid components are mixed together in a Sigma Mixet at 1400F (600C) at about 40 rpm to about 75 rpm for a period of from 15 minutes to about 30 minutes to provide a paste having the general consistency of 20,000A0,000 centipoise.

Once thoroughly mixed, the paste is stored at 140OF (60on) until agglomeration Step (B) is ready to be conducted.

SteD B - Agalomeration of Powders 'with Surfactant Paste - The purpose of this Step is to transform the base formula ingredients into flowable detergent agglomerates having a mean particle size range of from about 800 microns to about 1600 microns. In this Step, the powders (including materials such as zeolite. citrate, citric acid builder, layered silicate builder (as SKS-6), sodium carbonate, ethylenediaminedisuccinate. magnesium sulfate and optical brightener) are charged into the Eirich Mixer (R-Series) and mixed briefly (ca. 5 seconds - 10 seconds) at about 1500 rpm to about 3000 rpm in order to mix the various dry powders fully.The surfactant paste from Step A is then charged into the mixer and the mixing is continued at about 1500 rpm to about 3000 rpm for a period from about 1 minute to about 10 minutes, preferably 1-3 minutes, at ambient temperature.

The mixing is stopped when course agglomerates (average particle size 800-1600 microns) are formed.

Sten C - The purpose of this Step is to reduce the agglomerates' stickiness by removingidrying moisture and to aid in particle size reduction to the target particle size (in the mean particle size range from about 800 to about 1600 microns, as measured by sieve analysis). In this Step, the wet agglomerates are charged into a fluidized bed at an air steam temperature of from about 410C to about 60C and dried to a final moisture content of the particles from about 4% to about 10%.

Sten D - Coat AerPomerates and Add Free-Flow Aids - The objective in this Step is to achieve the final target agglomerate size range of from about 800 microns to about 1600 microns.

and to admix materials which coat the agglomerates. reduce the caking'lumping tendency of the particles and help maintain acceptable flowability. In this Step, the dried agglomerates from Step C are charged into the Eirich Mixer (R-Series) and mixed at a rate of about 1500 rpm to about 3000 rpm while adding 2-6% Zeolite A (median particle size 2-5pm) during the mixing. The mixing is continued until the desired median particle size is achieved (typically from about 5 seconds to about 45 seconds). At this point, from about 0.1% to about 1.5% by weight of precipitated silica (average particle size 1-3 microns) is added as a flow aid and the mixing is stopped.

In order to make the present invention more readily understood, reference is made to the following examples, which are intended to be illusuative only and not intended to be limiting in scope.

EXAMPLE I Several detergent compositions (A and B) are made in accordance with the agglomeration process described above. Composition A is within the scope of the invention and composition B is outside of the invention and is presented for purposes of comparison as described in Example II hereinafter. The relative proportions of compositions A and B, in agglomerate form, are listed in Table I below.

TABLE I (% weight Component A B C14 15 alkyl sulfate 8.2 7.9 C16 alkyl sulfate 24.5 23.7 C12-13 alkyl ethoxylate (3 mole) 6.6 6.4 N-methyl N-1-deoxyglucityl cocoamide 6.6 6.4 Polyethylene glycol (MW=4000) 2.0 2.0 Polyacrylate 8.7 8.4 Aluminosilicate 7.0 10.0 Citrate (Na) 2.7 2.6 Crystalline layered silicate 1 16.2 15.6 Potassium carbonate 17.2 Sodium carbonate - 16.7 Minors (water, perfume, etc.) 0.3 0.3 100.0 100.0 SKS6 crystalline layered sodium silicate commercially available from Hoechst.

EXAMPLE II This Example illustrates the surprisingly improved solubility achieved by the detergent composition of the invention. Specifically, standard dosages of compositions A and B (1170 ppm) are dissolved in an aqueous laundering solution having a water temperature of 10 C and a water hardness of 7 grains/gallon (Ca:Mg ratio of 3:1). The laundering solution is continuously agitated at a rate of 75 rpm and samples of the wash solution wcre taken at various time intervals as shown in Table I below.For purposes of illustrating the improved solubility of the detergent composition according to the invention, the amount of surfactant in the laundering solution is determined by convicting the well known "catSO3" titration technique on the samples taken from individual wash solutions containing one of the compositions A or B. In particular, the amount of anionic surfactant in the laundering solution is determined by filtering the samples through 0.45 nylon filter paper to remove the insolubles and thereafter, tiuating the filtered solution to which anionic dyes (dimidium bromide) have been added with a cationic titrant such as HyamineTi commercially available from Sigma Chemical Company.Accordingly. the relative amount of anionic surfactant dissolved in the wash solution can be determined. This technique is well known and others may be used if desired.

The results are shown in Table II below.

TABLE II (% total of anionic dissolved) Time (Minutes) A B 0 0% 0% 1 31% 22% 3 47% 45% 10 77% 58% From the results in Table ZI, it is quite clear that composition A which is within the scope of the invention surprisingly has improved solubility over composition B which is outside the scope of the invention.

EXAMPLE m A laundry bar C suitable for hand-washing soiled fabrics is prepared by a standard extrusion process and comprises the following ingredients listed in Table m: TABLE m (% weight) Component C C14.15 alkyl sulfate 8.2 C16 alkyl sulfate 24.5 C12 13 alkyl ethoxylate (3 mole) 6.6 N-methyl N-1-deoxyglucityl cocoamide 6.6 Polyethylene glycol (MW=4000) 2.0 Polyacrylate 8.7 Aluminosilicate 7.0 Citrate (Na) 2.7 Crystalline layered silicate 1 16.2 Potassium carbonate 17.2 Sodium carbonate Minors (water, perfiune. etc.) 0.3 100.0 1SKS-6 crystalline layered sodium silicate commercially available from Hoechst.

Having thus described the invention in detail, it will be obvious to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is described in the specification.

Claims (10)

1. A detergent composition having a density of at least 650 g/l characterized by: (a) from 1% to 50% by weight of a detersive surfactant system characterized by at least 30%, by weight of said surfactant system, of a sulfated surfactant selected from the group characterized by alkyl sulfates, alkyl ethoxy sulfates, secondary alkyl sulfates and mixtures thereof; (b) from 2% to 25% by weight of a potassium salt selected from the group characterized by potassium carbonate, potassium chloride, potassium sulfate and mixtures thereof; and (c) at least 1% by weight of a detergency builder; wherein said surfactant system. said potassium salt and said builder are agglomerated to form detergent agglomerates which are substantially free of phosphates; wherein said sulfated surfactant has improved solubility in an aqueous laundering solution.

2. A detergent composition according to claim 1 wherein said secondary alkyl sulfate surfactant is a secondary (2,3) alkyl sulfate.

3. A detergent composition according to claims 1-2 wherein said detergency builder is in an amount from 10% to 40% by weight.

4. A detergent composition according to claims 1-3 wherein said sulfated surfactant is a mixture of alkyl sulfate and alkyl ethoxy sulfate surfactants.

5. A detergent composition according to claims 1-4 wherein said potassium salt is potassium carbonate.

6. A detergent composition according to claims 1-5 further characterized by adjunct ingredients selected from the group characterized by bleaches, bleach activators, suds suppressers and soil release agents.

7. A detergent composition according to claims 1-6 wherein said detergency builder is selected from the group characterized by sodium carbonate, zeolites and mixtures thereof.

8. A detergent composition according to claims 1-7 wherein said surfactant system is further characterized by weight of said surfactant system, from 1% to 50% of a C10-C18 N-alkyl polyhydroxy fatty acid amide for use as an adjunct surfactant.

9. A detergent composition according to claims 1-8 wherein said sulfate surfactant is at least 5% more soluble in said detergent composition as compared to said sulfate surfactant dissolved alone in said aqueous laundering solution.

10. A method for laundering soiled fabrics characterized by the step of contacting said soiled fabrics with an effective amount of a detergent composition according to claims 1-9 in an aqueous laundering solution.