WO2010025552A1

WO2010025552A1 - Ternary surfactant composition comprising two anionic surfactants and one cationic surfactant

Info

Publication number: WO2010025552A1
Application number: PCT/CA2009/001217
Authority: WO
Inventors: Gerrard Marangoni; Kulbir Singh
Original assignee: St. Francis Xavier University
Priority date: 2008-09-08
Filing date: 2009-09-08
Publication date: 2010-03-11

Abstract

The invention is directed to a surfactant composition, uses thereof and a method for making the same. The surfactant composition comprises at least two anionic surfactants and at least one cationic surfactant. The surfactant composition is useful, for example, in cleaning products and/or personal care products.

Description

SURFACTANT COMPOSITIONS, USES THEREOF, AND METHOD FOR MAKING SAME

FIELD OF THE INVENTION

The present invention relates to surfactants. In particular, the present invention relates to surfactant compositions, uses thereof, and method for making same.

BACKGROUND OF THE INVENTION

Generally, binary anionic-cationic surfactant mixtures are known to detergent and personal care products industry, see for example, U.S. Patent Nos. 5,441 ,541 , 5,472,455, 5,204,010, 5,622,925, 5,607,980, 5,565,145, 4,333,862, 4,132,680, 5,610,187 and 4,247,538, and 4,273,760, which all describe various applications of binary cationic-anionic mixtures (hereafter catanionic) in commercial detergent and personal care applications.

Mixed surfactant systems have shown synergistic improvements in surfactant properties compared to the properties of their individual surfactant components. Synergism increases with the degree of charge difference. Thus, one would expect the greatest synergistic surfactant property improvements when mixing a binary system of anionic and cationic surfactants (see Rosen et al. in "Phenomena in Mixed Surfactant Systems" (Scamehorn, J. F., ed.), ACS Symposium Series 311 , Washington, D. C. (1986), pp. 144-162; Zhao et al. in "Phenomena in Mixed Surfactant Systems" (Scamehorn, J. F., ed.) ACS Symposium Series 311 , Washington, D.C. (1986) pp. 184-198.)

In the surfactant art, it is generally believed that, although the potential for synergism in surface tension reduction of binary catanionic systems is better compared to the properties of their individual surfactant components, anionic and cationic surfactants cannot be used in the same formula.

Therefore, the potential for the use of binary catanionic systems in detergent applications, for example hair and skin conditioning applications, is limited by the solubility of their mixtures. Thermodynamically, the K_sp, or solubility product constant, of binary catanionic systems is exceedingly small, thus limiting the use of such systems in consumer cleaning products and personal care products. Consequently, in detergent applications, for example, anionic and nonionic surfactants are typically used. However, cationic surfactants, especially quaternary ammonium salts, can decrease detergency and increase soil re-deposition when used in applications such as heavy-duty liquid detergents. Thus, there is a need for soluble anionic-cationic surfactant mixtures in the practice of detergent formulation.

The efficacy of catanionic mixtures is usually attributed to the fact that surfactant molecules of opposite charge pack more closely to each other in micelles due to the absence of any electrostatic repulsion. This close packing of the surfactants leads to an increase in the surface excess of the catanionic detergent and lower surface and interfacial tension. In the practice of soil removal, the ability to substantially lower surface and interfacial energies will affect the work of adhesion of the soil particle to the soiled surface, leading to more efficient soil removal. The strong synergistic effect on surface tension reduction for binary catanionic mixtures has been studied in the literature. As an example, when dilute solutions of sodium dodecylsulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) are mixed, a surface tension reduction of more than 40 dynes/cm is achieved. Also, the critical micelle concentration (CMC) and the minimum surface tension were lower for the mixture than for either one of the individual anionic or cationic surfactants (see for example, Lucassen-Reynders et al., J. Colloid Interface Sci., 81 , p. 150 (1981 )).

In mixed surfactant systems, the surfactant performance is gauged by the degree of synergistic interaction, the β value. The β value indicates whether or not the system exhibits positive or negative deviations from ideal behaviour. For a strongly interacting system, β is negative. For surface tension of mixed surfactant systems, this indicates how much lower the mixed system's actual surface tension is compared to its calculated, or ideal surface tension. It is known that surfactant mixtures exhibiting larger deviations between calculated and actual surface tension perform better; thus, surfactant performance increases with progressively more negative β values. Unfortunately, in catanionic mixtures, the variations in surfactant type and size that yield more favourable negative β values are accompanied by decreasing solubility. Hence, catanionic synergism is generally limited by the formation of an insoluble salt. Therefore, there is a need for a method for enhancing the solubility of catanionic surfactant mixtures. If a surfactant composition resulting from such a method possesses the maximum negative β values, one would expect enhancement of surface tension lowering compared to conventional surfactants and even conventional surfactant mixtures.

Prior art attempts to solubilize catanionic surfactant systems have included the use of organic solvents, such as butanol or ethanol, or the use of nonionic surfactants as solubilizing agents. Other prior art advocates the incorporation of polar organic functional groups (such as alkoxy groups) into the anionic and/or cationic surfactants. However, the use of volatile organic solvents presents certain occupational health and safety issues for detergent formulators such as a decreased flash point, and the inhalation of volatile vapours by formulators. The presence of pungent, off-putting organic odours can limit the consumer and commercial potential use of such formulations.

Therefore, there is a need to develop a method and resultant surfactant composition that obviates and mitigates at least some of the disadvantages of the prior art.

SUMMARY OF THE INVENTION

In an aspect, there is provided a surfactant composition comprising at least two anionic surfactants and at least one cationic surfactant. In another aspect, there is provided a method for making a surfactant composition comprising combining at least two anionic surfactants and at least one cationic surfactant.

In yet another aspect, there is provided a method for making a surfactant composition comprising combining at least one anionic surfactant and at least one cationic surfactant; and adding at least one other anionic surfactant to provide the surfactant composition, whereby a solution of the surfactant composition is non-turbid. In another aspect, there is provided a method for making a surfactant composition comprising combining at least one anionic surfactant and at least one cationic surfactant to form a turbid solution; and adding at least one other anionic surfactant such that the turbid solution becomes non-turbid. In yet another aspect, there is provided a surfactant composition made by the method described herein.

In another aspect, there is provided a cleaning product comprising the surfactant composition described herein.

In yet another aspect, there is provided a personal care product comprising the surfactant composition described herein.

In a further aspect, there is provided a use of the surfactant composition described herein in a cleaning product and/or a personal care product.

The novel features of the present invention will become apparent to those of skill in the art upon examination of the following detailed description of the invention. It should be understood, however, that the detailed description of the invention and the specific examples presented, while indicating certain embodiments of the present invention, are provided for illustration purposes only because various changes and modifications within the spirit and scope of the invention will become apparent to those of skill in the art from the detailed description of the invention and claims that follow.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The present invention is directed to surfactant compositions, uses thereof and method for making the same.

The following definitions are used herein and should be referred to for interpretation of the claims and the specification:

"Catanionic surfactant" means a binary cationic-anionic system that can encompass, for example, a mixture of a cationic and an anionic surfactant.

"Amphoteric surfactant" means a surfactant that behaves as a cationic surfactant at lower pH (for example, and without being limited thereto, a pH of about 2 to 6 or about 2.5 to 5.5, or about 4 to 5) or an anionic surfactant at higher pH (for example, and without being limited thereto, a pH of about 7.5 to 12, or about 8.0 to 10.5, or about 8.5 to 9.5).

"Non-turbid" means a solution that is clear or transparent to the naked eye or thereabout, which may be comparable to, for example, deionized water.

The term "heterogeneous chain" means a saturated or unsaturated chain of non-hydrogen member atoms comprising carbon atoms and at least one heteroatom. Heterogeneous chains typically have 1 to 25 member atoms. The chain may be cyclic, linear and/or branched, wherein the term "cyclic" encompasses, and without being limited thereto, saturated or unsaturated carbocyclic, heterocyclic, aryl and/or heteroaryl groups. Typical branched heterogeneous chains have one or two branches, more typically one branch. Typically, heterogeneous chains are saturated. Unsaturated heterogeneous chains may have one or more double bonds, one or more triple bonds, or both. Typical unsaturated heterogeneous chains have one or two double bonds or one triple bond. More typically, the unsaturated heterogeneous chain has one double bond.

The term "hydrocarbon chain" or "hydrocarbyl chain" means a saturated or unsaturated chain comprising carbon atoms. The hydrocarbon chains typically have 1 to 25 carbon atoms. Hydrocarbon chains may have a cyclic, linear and/or branched chain structure, wherein the term "cyclic" encompasses, and without being limited thereto, saturated or unsaturated carbocyclic and aryl groups. Typical hydrocarbon chains have one or two branches, typically one branch. Typically, hydrocarbon chains are saturated. Unsaturated hydrocarbon chains may have one or more double bonds, one or more triple bonds, or combinations thereof. Typical unsaturated hydrocarbon chains have one or two double bonds or one triple bond; more typically unsaturated hydrocarbon chains have one double bond. The term "substituted" used in conjunction with the chains described herein refers to a chemically acceptable group, i.e., a moiety that does not negate the activity of the inventive compounds. It is understood that substituents and substitution patterns on the compounds of the invention may be selected by one of ordinary skill in the art to provide compounds that are chemically stable and that can be readily synthesized by techniques known in the art. If a substituent is itself substituted with more than one group, it is understood that these multiple groups may be on the same carbon/member atom or on different carbons/member atoms, as long as a stable structure results. Illustrative examples of some suitable substituents include, cycloalkyl, heterocyclyl, hydroxyalkyl, benzyl, carbonyl, halo, haloalkyl, perfluoroalkyl, perfluoroalkoxy, alkyl, alkenyl, alkynyl, hydroxy, oxo, mercapto, alkylthio, alkoxy, aryl or heteroaryl, aryloxy or heteroaryloxy, aralkyl or heteroaralkyl, aralkoxy or heteroaralkoxy, HO-(C=O)-, amido, amino, alkyl- and dialkylamino, cyano, nitro, carbamoyl, alkylcarbonyl, alkoxycarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, arylcarbonyl, aryloxycarbonyl, alkylsulfonyl, and arylsulfonyl. In an embodiment, a surfactant composition comprises at least two anionic surfactants and at least one cationic surfactant. In a specific embodiment, the surfactant composition is a ternary composition comprising two anionic surfactants and one cationic surfactant. Examples of these surfactants are listed below. Amphoteric surfactants can be used as either a cationic surfactant of the surfactant composition at lower pH or an anionic surfactant of the surfactant composition at higher pH.

In other embodiments, the surfactant compositions are stable. The surfactant compositions can be in a dry form and/or solution. As a solution, the surfactant compositions further comprise at least one solvent, wherein the surfactant composition is soluble in the solvent. The solvent may be any suitable solvent. Examples of such solvents are water, low molecular weight alcohols (e.g. ethanol, methanol, propanol, butanol, glycol, etc.) or hydrocarbons, or a mixture thereof.

The surfactant composition of the invention may have a synergy. For example, the surfactant composition may possess greater solubility than a binary catanionic surfactant; the transport of the catanionic surfactant to the air-water interface is not limited by the catanionic surfactant's thermodynamic solubility. In a further embodiment, the surfactant compositions may have enhanced surface tension lowering capabilities compared to conventional surfactants and even conventional surfactant mixtures. The surfactant compositions described herein can have surface tensions less than that of its individual components. The surface tension of the surface composition can be less than about 30, less than about 20, from about 15 to about 29, from about 15 to about 26, or from about 20 to about 26.

The surfactant compositions described herein may be formulated into a variety of commercially useful products such as, for example and without be limited thereto, cleaning products and personal care products. Some examples of cleaning products include, and without being limited thereto, dish and laundry detergents, such as liquid laundry formulations, powder laundry formulations, and dishwasher detergents, car wash formulations, or a mixture thereof. Some examples of personal care products include, and without being limited thereto, shampoos, conditioners, body washes, foam baths, shower gels, or a mixture thereof.

The amount of surfactant composition in a product can be any suitable amount. Typically, the composition is present in the product from about 1 % (w/v) to about 70 % (w/v), more typically from about 5 % (w/v) to about 60% (w/v), and most typically from about 20 % (w/v) to about 50% (w/v), based on the total % (w/v) of the product. If the product is a solid composition, similar ranges in % (w/w) may be used.

In practical terms, the surfactant compositions can improve the efficacy of a number of commercial detergent formulations. Concentrated solutions of catanionic surfactant systems can be prepared resulting in smaller production volumes, and better surface tension reduction per amount of active surfactant in the formulation. The surfactant composition can be used in a concentrated solution. In the push to produce new, more efficient detergent formulations, the ability to utilize the surfactant composition described herein in a concentrated liquid form may lead to reductions in packaging dimensions and cost, and reduced transportation costs. Reduced surfactant consumption may mean less discharge to the environment resulting in newer, greener detergents.

Cationic surfactants that may be used in the surfactant composition described herein are any suitable cationic surfactants. For example, the cationic surfactant may be any cationic surfactant that, as a component of the surfactant composition described herein, forms a stable surfactant composition, in particular, a more soluble surfactant composition compared to a binary catanionic surfactant system. Examples of cationic surfactants include, but are not limited thereto, cationic surfactants having various substituted or unsubstituted hydrocarbyl chains or substituted or unsubstituted heterogeneous chains, for example, substituted or unsubstituted hydrocarbyl chain lengths, such as about C₈ to C₂2, about Ci₀ to C-iβ, or, C12 to Ci₆; those skilled in the art will recognize that the final chain length will be determined by the application of the composition (e.g. shampoo, conditioner, dish detergent, etc.). Typical chains are alkyl, alkoxyalkyl, alkylaryl, or alkylamidoalkyl.

Gemini surfactants may also be used, for example, gemini surfactants having various chain lengths and spacers such as, and without being limited thereto:

Ri represents a hydrogen atom or a hydrocarbyl chain such as an alkyl, alkoxyalkyl, alkylaryl, or alkylamidoalkyl, wherein alkyl represents a group that contains from about 1 to 4 carbon atoms which may be branched or straight chained. R₂ and R₃ are each independently selected from a hydrogen atom or a hydrocarbyl chain such as an alkyl, alkenyl, arylalkyl, hydroxyalkyl, or alkylamidoalkyl having from about 1 to 4 carbon atoms. Some alkyl chains are methyl, ethyl, alkylaryl can be benzyl, and hydroxyalkyl can be hydroxyethyl or hydroxypropyl. N can be any integer, typically, 1 to 6. The amine groups may be primary, secondary, tertiary, and depending on the pH may or not possess a positive charge. If the nitrogen atoms are charged, either due to pH effects or due to quarternary substitution, counterions (X^") will be present. These counterions may be any of the common halides (Br^", Cl^", I^"), hydroxide, acetate, formate, propionate, or an exemplar of counterions commonly used in amine preparations. Other cationic surfactants include ammonium surfactants, substituted ammonium surfactants such as alkyl substituted ammonium surfactants, quaternary ammonium surfactants (e.g. Arquads™), pyridinium surfactants, or substituted pyridinium surfactants such as alkyl substituted pyridinium surfactants, are some examples that can be used herein. Some specific examples of cationic surfactants include octyltrimethylammonium bromide (OTAB), decyltrimethylammonium bromide (DeTAB), dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (HTAB), tetradecylpyridinium bromide (Ci₄PyBr), cetylpyridinium bromide (Ci₆PyBr), decyltriphenylphosphonium bromide (DeTPPB), dodecyltriphenylphosphonium bromide (DTPPB), hexamethylene-Bis-[N,N- dimethylammonium] bromide (12-6-12), pentamethylene-Bis-[N,N- dimethylammonium] bromide (12-5-12), or a mixture thereof.

In specific embodiments, a surfactant composition comprising a cationic surfactant having a single tailed cationic surfactant with a quaternary ammonium head group is efficient in lowering surface tension.

Anionic surfactants that may be used in the surfactant composition described herein are any suitable anionic surfactants. For example, the anionic surfactant may be any anionic surfactant that, as a component of the surfactant composition described herein, forms a stable surfactant composition, in particular, a more soluble surfactant composition compared to a binary catanionic surfactant system. Examples of anionic surfactants include, but are not limited thereto, anionic surfactants having various substituted or unsubstituted hydrocarbyl chains or substituted or unsubstituted heterogeneous chains, for example, substituted or unsubstituted hydrocarbyl chain lengths, such as about C₈ to C22, about Ci₀ to Ci₈, or, C12 to Ci₆; those skilled in the art will recognize that the final chain length will be determined by the application of the composition (e.g. shampoo, conditioner, dish detergent, etc.). Typical chains are alkyl, alkoxyalkyl, alkylaryl, or alkylamidoalkyl. Sulfonates and sulfates are typically used as anionic surfactants. Sulfonates, sulfates, and carboxylates, and sometimes phosphates, can be used as anionic surfactants. Others include polyelectrolytes such as alkali metal polyelectrolytes, such as sodium polyelectrolytes, more particularly, polystyrene sulfate or polyacrylates. Some specific examples of anionic surfactants include, but are not limited thereto, sodium dodecyl sulfate (SDS), sodium decylsulfate (SDeS), sodium octyl sulfate (SOS), ammonium ether sulfate (e.g., Cedepal™ FA-406), or a mixture thereof.

In particular embodiments, a more effective surfactant composition is provided when the hydrocarbon chain of the cationic surfactant is equal to the hydrocarbon chain of the anionic surfactant; for example, if the cationic surfactant is DTAB and the anionic surfactant is SDS. As mentioned above, amphoteric surfactants can act as a cationic surfactant or an anionic surfactant, depending on the pH. The amphoteric surfactant may be any amphoteric surfactant that, as a component of the surfactant composition described herein, forms a stable surfactant composition, in particular, a more soluble surfactant composition compared to a binary catanionic surfactant system. Examples of amphoteric surfactants include, but are not limited thereto, a surfactant having various substituted or unsubstituted hydrocarbyl chains or substituted or unsubstituted heterogeneous chains, for example, substituted or unsubstituted hydrocarbyl chain lengths, such as about C₈ to C22, about Ci₀ to Ci₈, or, C12 to C-iβ; those skilled in the art will recognize that the final chain length will be determined by the application of the composition (e.g. shampoo, conditioner, dish detergent, etc.) Typical chains are alkyl, alkoxyalkyl, alkylaryl, or alkylamidoalkyl. The cation of the amphoteric surfactant is typically ammonium, substituted ammonium such as alkyl substituted ammonium, and quaternary ammonium. The anion of the amphoteric surfactant is typically, carboxylate, sulfate or sulfonate. Some specific examples of amphoteric surfactants include, without being limited thereto, alkyl betaine, amino betaine, N-alkyl beta- alanine, amido betaine, imidazoline betaine.

In specific embodiments, surfactants are chosen so that the resultant surfactant composition described herein is compatible with most additives in consumer product formulations.

The surfactant composition may comprise from about 4 % (w/w) to about 50 % (w/w) of the at least one cationic surfactant; from about 0.5 % (w/w) to about 25 % (w/w) of the at least one anionic surfactant; and from about 25 % (w/w) to about 95.5 % (w/w) of the at least one other anionic surfactant. More typically, the surfactant composition may comprise from about 10 % (w/w) to about 45 % (w/w) of the at least one cationic surfactant; from about 2 % (w/w) to about 25 % (w/w) of the at least one anionic surfactant; and from about 30 % (w/w) to about 88 % (w/w) of the at least one other anionic surfactant, based on the total % (w/w) of the surfactant composition.

The method for making the surfactant compositions described herein may include, for example, a method comprising combining at least two anionic surfactants and at least one cationic surfactant. In a specific embodiment, the method comprises combining two anionic surfactants and one cationic surfactant to form a ternary surfactant system. Examples of possible surfactants used in the method are listed above. As mentioned above, amphoteric surfactants can be used as either a cationic surfactant of the surfactant composition at lower pH or an anionic surfactant of the surfactant composition at higher pH. In other method embodiments, the method for making the surfactant composition comprises combining at least one anionic surfactant and at least one cationic surfactant. At least one other anionic surfactant is added to the combination of the anionic surfactant and the cationic surfactant to provide a surfactant composition. A solution of the surfactant composition is non-turbid. In addition, the combination of the at least one anionic surfactant and the at least one cationic surfactant form a catanionic surfactant system. In a specific embodiment, a method comprises combining one anionic surfactant and one cationic surfactant to form a catanionic surfactant system. At least one other anionic surfactant is added to the combination of the anionic surfactant and the cationic surfactant to provide a surfactant composition. A solution of the surfactant composition is non-turbid. More specifically, the other anionic surfactant is one anionic surfactant and thus, the surfactant composition is a ternary system. As mentioned above, amphoteric surfactants can be used as either a cationic surfactant of the surfactant composition at lower pH or an anionic surfactant of the surfactant composition at higher pH.

Although not critical, the surfactant compositions may be prepared neat or in a conventional solvent such as water, low molecular weight alcohol (e.g. methanol, ethanol, propanol, butanol, glycol etc.) or hydrocarbon, or a mixture thereof, to produce a solution of the ternary surfactant blend. The surfactant compositions in concentrations up to 100 percent by weight may be isolated by drying a solution of the blend by any of a number of means apparent to those skilled in the art (e.g. lyophilization).

In a specific embodiment, the method for making the surfactant compositions described herein may include, for example, a method comprising combining at least one anionic surfactant and at least one cationic surfactant, wherein at least one of the anionic and cationic surfactants is a solution. The anionic and cationic surfactants can form a catanionic surfactant system. At least one other anionic surfactant is added to the combination of the anionic surfactant and the cationic surfactant to provide a surfactant composition. A solution of the surfactant composition is non-turbid. In a further embodiment, the other anionic surfactant is a solution.

In another particular embodiment, there is provided a method comprising combining one anionic surfactant and one cationic surfactant to form a catanionic surfactant system, wherein at least one of the anionic surfactant and the cationic surfactant is a solution. At least one other anionic surfactant is added to the combination of the anionic surfactant and the cationic surfactant to provide a surfactant composition. A solution of the surfactant composition is non-turbid. More specifically, the other anionic surfactant is one anionic surfactant and thus, the surfactant composition is a ternary system. In a further embodiment, the other anionic surfactant is a solution. As mentioned above, amphoteric surfactants can be used as either a cationic surfactant of the surfactant composition at lower pH or an anionic surfactant of the surfactant composition at higher pH.

In further examples of the method, the method comprises combining at least one anionic surfactant and at least one cationic surfactant to form a turbid solution. At least one other anionic surfactant is added to the turbid solution such that the turbid solution becomes non-turbid. In a further embodiment, the other anionic surfactant is a solution. In another embodiment, the turbid solution is a turbid catanionic surfactant solution.

In another particular embodiment, there is provided a method comprising combining one anionic surfactant and one cationic surfactant to form a turbid catanionic surfactant solution. At least one other anionic surfactant is added to the turbid solution such that the turbid solution becomes non-turbid. More specifically, the other anionic surfactant is one anionic surfactant and thus, the surfactant composition is a ternary system.

The amount of the at least one anionic surfactant that is combined with the at least one cationic surfactant, for example, is such that a turbid solution is formed. Such amounts of the at least one anionic surfactant to the at least one cationic surfactant are typically from about 50:1 to about 1 :50 (%w/v), from about 30:1 to about 1 :30 (%w/v); from about 20:1 to about 1 :20 (%w/v); from about 5:1 to about 1 :5, or from about 3:1 to about 1 :3 (%w/v) based on the total % (w/v) of solution. Most typically, the at least one anionic surfactant to the at least one cationic surfactant have similar concentrations and chain lengths. The amount of the at least one other anionic surfactant is such that the turbid solution becomes non-turbid. Such amounts of the other anionic surfactant include, for example, from about 0.1 % (w/v) to about 40 % (w/v); from about 0.5 % (w/v) to about 30 % (w/v); or from about 1 % (w/v) to about 20 % (w/v) based on the total % (w/v) of solution. The actual % (w/w) will depend on the final density of the solution and the measurement of the density can be achieved by known techniques.

The turbid solutions described above may be mixed and left for at least about 1.5 hours prior to the addition of the other anionic surfactant. During the combination stage of the methods described herein, the components (e.g. the at least one anionic surfactant and cationic surfactant) can be stirred. Moreover, the components can continue to be stirred while the other anionic surfactant is added. An excess of the other anionic surfactant can be added after the solution is no longer turbid. Typically, this excess is a small amount. Additional water may also be added to a solution of the surfactant composition to determine if the surfactant solution remains non- turbid or stable to dilution. Therefore, the non-turbidity can be permanent. In typical embodiments, the addition of components can be achieved using any suitable addition method, typically, through titration. In typical embodiments, the surfactant composition prepared by this method possesses greater solubility than a catanionic surfactant system; the transport of the catanionic surfactant to the air-water interface is not limited by its thermodynamic solubility.

Without being bound by theory, it is thought that the interaction parameter (beta value) between a cationic surfactant and an anionic surfactant is more negative than the interaction parameter between the cationic surfactant and another anionic surfactant in the composition. Hence, the other anionic surfactant (e.g. Cedepal) is not a "strong enough surfactant" thermodynamically to replace the anionic surfactant (e.g. SDS) in the catanionic complex. In addition, with respect to the Ksp values of the catanionic surfactant, the Ksp for the anionic surfactant (e.g. SDS) and the cationic surfactant (e.g. DTAB) is less than the Ksp for the other anionic surfactant (e.g. Cedepal) and the cationic surfactant (e.g. DTAB). Therefore, instead of the other anionic surfactant (e.g. Cedepal) replacing the anionic surfactant (e.g. SDS) in the complex, it merely solubilizes it. Therefore, Ksp values and/or beta values can be used to determine the combination of surfactants in the composition of the invention. The above disclosure generally describes the present invention. A more complete understanding can be obtained by reference to the following specific Examples. The Examples are described solely for purposes of illustration and are not intended to limit the scope of the invention. Changes in form and substitution of equivalents are contemplated as circumstances may suggest or render expedient. Although specific terms have been employed herein, such terms are intended in a descriptive sense and not for purposes of limitation.

Examples

In Tables 1 and 2 listed below, the acronyms are defined as follows: octyltrimethylammonium bromide (OTAB), decyltrimethylammonium bromide

(DeTAB), dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (HTAB), tetradecylpyridinium bromide (C₁₄PyBr), decyltriphenylphosphonium bromide (DeTPPB), dodecyltriphenylphosphonium bromide (DTPPB), hexamethylene-Bis-[N,N- dimethylammonium] bromide (12-6-12), pentamethylene-Bis-[N,N- dimethylammonium] bromide (12-5-12), sodium dodecyl sulfate (SDS), sodium decylsulfate (SDeS), and ammonium ether sulfate (Cedepal™ FA-406 is a 60% (w/v) solution).

Method: A 2% (w/v) aqueous solution of an anionic surfactant (e.g., SDS or

SDeS) (amounts used are listed in the Tables) was gradually added to a stirred solution (about 2 ml_) of a 2% (w/v) aqueous cationic surfactant solution (e.g., a surfactant listed in the Tables) until the mixed solution became turbid. This solution, referred to as Solution A, was allowed to sit for at least about 1.5 hrs. Then a third component, another anionic surfactant, Cedepal™ FA-406 (60% (w/v) solution), was added with continuous stirring to Solution A until it became non-turbid. A small excess of Cedepal™ FA-406 was added and the resulting non-turbid solution, referred to as Solution B, was allowed to stand for about 48 hrs. Solution B was diluted with water to check for precipitation of the surfactant composition from the mixture. Surfactant compositions prepared in this manner were found to be stable towards dilution. Such dilution ranges, to yield a non-turbid composition, would be readily apparent to those skilled in the art. Surface tension measurements were obtained, using known standard methods, at various dilutions of Solution B; the surface tension data is presented in Tables 1 , 1A, 1 B and 1 C (SDS) and 2, 2A, 2B and 2C (SDeS). Surface tension measurements for dilute cedepal (10% (w/v) aqueous solution and 20% (w/v) aqueous solution) were provided for comparison data.

Table 1:

A Ternary Blend of A Cationic Surfactant, Cedepal TM , and SDS

With respect to the results shown in Table 1 , ratios of components are shown in Table 1A. Ratios were calculated using N1V1 = N₂V₂ taking N₁ as 60% (w/v) for Cedepal, 2% (w/v) for SDS or 2% (w/v) Cationic Surfactant, V₂ is the total volume of the solution). Table 1A:

Table 1B: A Ternary Blend of A Cationic Surfactant, Cedepal™, and SDS

CD

With respect to the results shown in Table 1 B, ratios of components are shown in Table 1C. Ratios were calculated using N-₁V1 = N₂V₂ taking N₁ as 60% (w/v) for Cedepal, 2% (w/v) for SDS or % (w/v) Cationic Surfactant is listed in the table, V₂ is the total volume of the solution.

Table 1C:

Table 2:

A Ternary Blend of A Cationic Surfactant, Cedepal™. and SDeS

With respect to the results shown in Table 2, ratios of components are shown in Table 2A. Ratios were calculated using NiV₁ = N₂V₂ taking N₁ as 60% (w/v) for Cedepal, 2% (w/v) for SDeS or 2% (w/v) Cationic Surfactant, V₂ is the total volume of the solution). Table 2A:

Table 2B: A Ternary Blend of A Cationic Surfactant Cedepal™, and SDeS

N)

With respect to the results shown in Table 2B, ratios of components are shown in Table 2C. Ratios were calculated using N₁V₁ = N₂V₂ taking N₁ as 60% (w/v) for Cedepal, 2% (w/v) for SDS or % (w/v) Cationic Surfactant is listed in the table, V₂ is the total volume of the solution).

Table 2C:

From the data listed in the tables, it is shown that surfactant blends containing single tailed cationic surfactants with quarternary ammonium head groups are the most efficient in lowering surface tension. The effect is much more pronounced when the hydrocarbon chain of the cationic surfactant is equal to the anionic surfactant (for example, for the cationic surfactant DTAB mixed with the anionic surfactant SDS).

When introducing elements disclosed herein, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements. The terms "comprising", "having", "including" are intended to be open-ended and mean that there may be additional elements other than the listed elements.

All ranges given herein include the end of the ranges and also any intermediate range points.

Claims

WE CLAIM:

1. A surfactant composition comprising at least two anionic surfactants and at least one cationic surfactant.

2. The surfactant composition of claim 1 , wherein an amphoteric surfactant is said at least one cationic surfactant at lower pH or an anionic surfactant of the surfactant composition at higher pH.

3. The surfactant composition of claim 1 or 2, wherein the surfactant composition is a ternary composition comprising two anionic surfactants and one cationic surfactant.

4. The surfactant composition of any one of claims 1 to 3, wherein the surfactant composition is in a dry form or solution.

5. The surfactant composition of any one of claims 1 to 4, wherein the surfactant composition further comprises at least one solvent, wherein the composition is soluble in the solvent.

6. The surfactant composition of claim 5, wherein the solvent is selected from water, low molecular weight alcohols or hydrocarbons, or a mixture thereof.

7. The surfactant composition of any one of claims 1 to 6, wherein the composition has a greater solubility than a binary catanionic surfactant.

8. The surfactant composition of any one of claims 1 to 7, wherein the composition has enhanced surface tension lowering capabilities compared to conventional surfactants and conventional surfactant mixtures.

9. The surfactant composition of any one of claims 1 to 9, wherein the composition has a surface tension less than that of its individual components.

10. The surfactant composition of claim 9, wherein the surface tension is less than about 30.

11. The surfactant composition of claim 9, wherein the surface tension is from about 15 to about 26.

12. The surfactant composition of any one of claims 1 to 11 , wherein said at least one cationic surfactant is any cationic surfactant that forms a stable surfactant composition.

13. The surfactant composition of any one of claims 1 to 11 , wherein said at least one cationic surfactant is any cationic surfactant that forms a stable surfactant composition such that the surfactant composition is more soluble than that compared to a binary catanionic surfactant system.

14. The surfactant composition of any one of claims 1 to 13, wherein said at least one cationic surfactant is selected from octyltrimethylammonium bromide (OTAB), decyltrimethylammonium bromide (DeTAB), dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (HTAB), tetradecylpyridinium bromide (Ci₄PyBr), cetylpyridinium bromide (Ci₆PyBr), decyltriphenylphosphonium bromide (DeTPPB), dodecyltriphenylphosphonium bromide (DTPPB), hexamethylene-Bis-[N,N- dimethylammonium] bromide (12-6-12), pentamethylene-Bis-[N,N- dimethylammonium] bromide (12-5-12), or a mixture thereof.

15. The surfactant composition of any one of claims 1 to 14, wherein said at least one cationic surfactant is a single tailed cationic surfactant with a quarternary ammonium head group.

16. The surfactant composition of any one of claims 11 to 15, wherein a hydrocarbon chain of said at least one cationic surfactant is equal to the hydrocarbon chain of one of said at least two anionic surfactants.

17. The surfactant composition of any one of claims 1 to 16, wherein said at least two anionic surfactants are any anionic surfactants that form a stable surfactant composition.

18. The surfactant composition of any one of claims 1 to 16, wherein said at least two anionic surfactants are any anionic surfactants that form a stable surfactant composition such that the surfactant composition is more soluble than that compared to a binary catanionic surfactant system.

19. The surfactant composition of any one of claims 1 to 18, wherein said at least two anionic surfactants are selected from sodium dodecyl sulfate (SDS), sodium decylsulfate (SDeS), sodium octyl sulfate (SOS), ammonium ether sulfate, or a mixture thereof.

20. The surfactant composition of any one of claims 1 to 19, wherein a beta value between an anionic surfactant and said cationic surfactant is more negative than the beta value between said cationic surfactant and another anionic surfactant.

21. The surfactant composition of any one of claims 1 to 19, wherein a Ksp value between an anionic surfactant and said cationic surfactant is less than a Ksp of said cationic surfactant and another anionic surfactant.

22. The surfactant composition of any one of claims 1 to 21 , wherein said at least one cationic surfactant is from about 4 % (w/w) to about 50 % (w/w), said at least one anionic surfactant is from about 0.5 % (w/w) to about 25 % (w/w), and said at least one other anionic surfactant is from about 25 % (w/w) to about 95.5 % (w/w) based on the total weight of the composition.

23. A method for making a surfactant composition comprising combining at least two anionic surfactants and at least one cationic surfactant.

24. The method of claim 23, wherein an amphoteric surfactant is said at least one cationic surfactant at lower pH or an anionic surfactant of the surfactant composition at higher pH.

25. The method of claim 23 or 24, wherein the surfactant composition is a ternary composition comprising two anionic surfactants and one cationic surfactant.

26. A method for making a surfactant composition comprising combining at least one anionic surfactant and at least one cationic surfactant; and adding at least one other anionic surfactant to provide the surfactant composition, whereby a solution of the surfactant composition is non-turbid.

27. The method of claim 26, wherein said at least one anionic surfactant and said at least one cationic surfactant forms a catanionic surfactant system.

28. The method of claim 26 or 27, wherein said surfactant composition is a ternary surfactant system, wherein said at least one anionic surfactant, said at least one cationic surfactant, and said at least one other anionic surfactant is one anionic surfactant, one cationic surfactant, and one other anionic surfactant, respectively.

29. The method of any one of claims 26 to 28, wherein at least one of said at least one anionic surfactant and said at least one cationic surfactant is a solution.

30. The method of claim 29, wherein said at least one other anionic surfactant is a solution.

31. A method for making a surfactant composition comprising combining at least one anionic surfactant and at least one cationic surfactant to form a turbid solution; and adding at least one other anionic surfactant such that the turbid solution becomes non-turbid.

32. The method of claim 31 , wherein said at least one other anionic surfactant is a solution.

33. The method of claim 31 or 32, wherein said at least one anionic surfactant and said at least one cationic surfactant forms a catanionic surfactant system.

34. The method of any one of claims 31 to 33, wherein said surfactant composition is a ternary surfactant system, wherein said at least one anionic surfactant, said at least one cationic surfactant, and said at least one other anionic surfactant is one anionic surfactant, one cationic surfactant, and one other anionic surfactant, respectively.

35. The method of any one of claims 26 to 34, wherein the solution comprises a solvent selected from water, low molecular weight alcohol or hydrocarbon, or a mixture thereof.

36. The method of any one of claims 23 to 35, wherein an amount of said at least one anionic surfactant to said at least one cationic surfactant is from about 50:1 to about 1 :50 (%w/v) based on total % (w/v) of solution.

37. The method of claim 36, wherein an amount of said at least one anionic surfactant to said at least one cationic surfactant is from about 30:1 to about 1 :30 (%w/v).

38. The method of claim 37, wherein an amount of said at least one anionic surfactant to said at least one cationic surfactant is from about 20:1 to about 1 :20 (%w/v).

39. The method of any one of claims 36 to 38, wherein an amount of said at least one other anionic surfactant is from about 0.1 % (w/v) to about 40 %

(w/v) based on total % (w/v) of solution.

40. The method of claim 39, wherein an amount of said at least one other anionic surfactant is from about 0.5 % (w/v) to about 30 % (w/v).

41. The method of claim 39, wherein an amount of said at least one other anionic surfactant is from about 1 % (w/v) to about 20 % (w/v).

42. The method of any one of claims 31 to 41 , wherein the combination is stirred.

43. The method of any one of claims 31 to 42, wherein the combination is left for at least about 1.5 hours prior to the addition of said at least one other anionic surfactant.

44. The method of any one of claims 31 to 43, wherein an excess of said at least one other anionic surfactant is added after the solution is no longer turbid.

45. A surfactant composition made by the method of any one of claims 23 to 44.

46. A product comprising the surfactant composition of any one of claims 1 to 22 and 45.

47. The product of claim 46, wherein the product is a cleaning product and/or a personal care product.

48. The product of claim 47, wherein the cleaning product is a detergent.

49. The product of claim 47, wherein the cleaning product is selected from dish and laundry detergents, liquid laundry formulations, powder laundry formulations, dishwasher detergents, car wash formulations, or a mixture thereof.

50. The product of claim 47, wherein the personal care product is selected from shampoos, conditioners, body washes, foam baths, shower gels, or a mixture thereof.

51. The product of any one of claims 46 to 50, wherein the surfactant composition is in a concentrated solution.

52. The product of any one of claims 46 to 51 , wherein the surfactant composition is present in the product from about 1 % (w/v) to about 70 % (w/v) based on total % (w/v) of the product.

53. The product of claim 52, wherein the surfactant composition is present in the product from about 10 % (w/v) to about 60% (w/v).

54. Use of the surfactant composition of any one of claims 1 to 22 and 45 in a product.

55. The use of claim 54, wherein the product is selected from a cleaning product and/or a personal care product.

56. The use of claim 55, wherein the cleaning product is a detergent.

57. The use of claim 55, wherein the cleaning product is selected from dish and laundry detergents, liquid laundry formulations, powder laundry formulations, dishwasher detergents, car wash formulations, or a mixture thereof.

58. The use of claim 55, wherein the personal care product is selected from shampoos, conditioners, body washes, foam baths, shower gels, or a mixture thereof.

59. The use of any one of claims 54 to 58, wherein the surfactant composition is in a concentrated solution.

60. The use according to any one of claims 54 to 59, wherein the surfactant composition is present in the product from about 1 % (w/v) to about 70 % (w/v) based on total % (w/v) of the product.