DE69113055T2 - LIQUID DETERGENT COMPOSITIONS. - Google Patents

Description

Field of the invention

This invention relates generally to aqueous liquid detergent compositions and more particularly to liquid detergent compositions intended for the removal of predominantly greasy soils from hard surfaces such as dishes and other articles used in the preparation and consumption of food.

Basis of the invention

Liquid detergent compositions intended for use as dishwashing products are conventionally in the form of aqueous solutions containing a mixture of one or more anionic sulphate and sulphonate detergents as the main surfactant materials together with a foam-promoting or stabilising agent. The foam stabilising agent may take a number of forms but is usually an amide derivative, an amine oxide, an ethoxylated aliphatic alcohol, a zwitterionic surfactant such as a betaine or a mixture of several of these. The use levels of these types of materials are conventionally in the range of 2-8%, usually 3-5%, by weight of the composition.

One group of amide derivatives that have been proposed for foam promotion and stabilization purposes are the N-alkanoyl-N-alkylglucamines. These materials are derived from glucose and can be prepared by reacting a lower alkylamine with glucose to form a glucamine and then treating the glucamine with a methyl ester of a fatty acid of the required chain length to obtain the N-alkanoyl-N-alkylglucamine.

Compounds of this type are described, for example, in US-A-2703798, WO83/04412, EP-A-285 768 and GB-A-809060. EP-A-285 768 describes the use of N-polyhydroxyalkyl fatty acid amides as thickeners for liquid aqueous surface-active systems. GB-A-809060 describes detergent compositions which contain at least one water-soluble salt of an organic sulphuric acid reaction product with a sulphuric acid or a sulphonic acid residue in its molecular structure and an amide derivative of the above type in an amount of from 5% to 60% by weight of the water-soluble organic sulfuric acid reaction product. The amide derivatives are said to provide an improvement in the foaming properties of the compositions at temperatures below 100°F, particularly in Latin American countries where washing is carried out at temperatures as low as 60°F. Although the patent specifies that the surfactant combination can be used alone, the preferred and exemplified embodiments are granular products containing phosphate as a builder and sodium sulfate as a filler.

The Applicant has now found that builder-free liquid or gel detergent compositions containing as main surfactants combinations of certain N-alkanoyl-N-alkylglucamines and sulfated or sulfonated surfactants provide a significant improvement in the removal of greasy soil from hard surfaces with a higher foaming performance and notable benefits in terms of mildness to the skin compared to known products. Although mixtures of anionic sulfate or sulfonate surfactants and N-alkanoyl-N-alkylglucamines have been proposed as means for improving the foaming of builder-containing products at low washing temperatures, the aspects of greasy soil removal performance and properties relating to mildness to the skin now found for the mixtures have not been recognized until now.

According to the present invention there is therefore provided a builder-free liquid or gel detergent composition in the form of a physically stable aqueous solution comprising from 20% to 50% by weight of the composition of a main surfactant mixture which, based on the weight of the mixture,

a) 5 to 95% of at least one water-soluble anionic surfactant sulfate or sulfonate salt;

b) 95% to 5%, based on the weight of the mixture, of one or more compounds of the general formula

wherein Z is a polyhydroxyhydrocarbon radical having a linear hydrocarbon chain with at least 3 hydroxy groups directly attached to the chain, which radical is derived from glucose and mixtures thereof with maltose, wherein the maltose represents not more than 33% by weight of the mixture, R represents a saturated or unsaturated aliphatic group having 8 to 16 carbon atoms or a mixture of such groups and R₁ represents a C₁-C₄ alkyl or C₂-C₄ hydroxyalkyl group;

wherein a 0.12 wt.% aqueous solution of the surfactant mixture of the said composition in water of 2º Clark mineral hardness (Ca:Mg ratio 3:1) and a temperature of 48ºC

(i) a spinning drop interfacial tension (IFT) of less than 0.2 Pa.cm using a triolein soil of 99.7% purity;

(ii) has a greasy soil removal value in the Polypropylene Cup (PPC) test of at least 1,4 times the value obtained in the same test under the same conditions using a 0,12% solution of the anionic surfactant component(s) only.

For the purposes of the present invention, "physically stable" shall mean maintaining a single phase condition without precipitation after three months of storage at a temperature of 21°C. If the product contains an opacifier, little or no settling of the opacifier should have occurred. In addition, for the purposes of the IFT & PPC test measurements of the present invention, the cation(s) of the water-soluble anionic sulfate or sulfonate surfactant should be such that they correspond to the cation(s) in the detergent composition and, in the case of a cation mixture, be present in the proportions by weight in which each individual cation is present in the mixture.

In preferred compositions according to the invention, compounds are used as component (b) in which the polyhydroxyhydrocarbon residues are obtained from glucose or mixtures thereof with maltose, in which the maltose represents < 25% by weight of the mixture. Commercially available technical grade glucose contains maltose as an impurity in an amount up to 5% by weight. For the purposes of the present invention, the references below to glucamines are considered to be those to materials containing up to 5% by weight of the corresponding material of maltose.

Suitable anionic sulfate or sulfonate surfactants include C10-C16 alkyl ethoxysulfates containing an average of up to 6 moles of ethylene oxide per mole of alkyl ethoxysulfate, C10-C18 paraffin sulfonates, and N-C9-C17 acyl-N-C1-C4 alkyl glucamine sulfates.

Suitable compositions according to the invention contain an anionic surfactant system comprising from 9% to 18% by weight of the composition of a primary C₁₂-C₁₄ alkyl ethoxysulfate starting material having an average of 0.4 to 4.0 ethylene oxide groups per mole of C₁₂-C₁₄ alkyl ethoxysulfate, preferably 0.3 to 3.0, together with from 9% to 15% by weight of the composition of N-coconut acyl-N-methylglucamine.

In preferred compositions, a weight ratio of anionic surfactant to glucamine of from 2:1 to 1:1 is employed. Particularly preferred compositions contain from 10% to 18% by weight of C12-C14 alkyl ethoxysulfate and from 7% to 15% by weight of the glucamine surfactant. The alkyl ethoxysulfates themselves comprise a mixture of a material having an average of about 0.8 moles ethylene oxide/mole and a material having an average of about 3.0 moles ethylene oxide/mole in a weight ratio of from 2:1 to 5:1, preferably about 4:1.

Preferred compositions according to the invention also contain from 1% to 8% by weight, most preferably from 2% to 7% by weight of a foam booster selected from C₁₀-C₁₆ alkyl mono- or di-C₂-C₃ alkanolamides, C₁₂-C₁₄ alkyl or alkylamidobetaines, C₁₂-C₁₄ alkylsulfobetaines, C₁₀-C₁₆ alkyl di-C₁-C₄ alkyl or di-C₂-C₄ hydroxyalkylamine oxides, ethoxylates of C₉-C₁₆ primary alcohol having an average of 7 to 12 ethylene oxide groups per mole of alcohol and mixtures thereof.

Preferred foam boosters comprise mixtures of C12-C14 alkyl betaine in an amount of from 1% to 5%, preferably from 1.5% to 3% by weight of the composition, together with C9-C12 primary alcohol ethoxylate (preferably C10 alkyl EO8) in an amount of from 6% to 8% by weight of the composition.

Another preferred component of such compositions is Mg⁺⁺ in an amount up to 1.5%, more preferably from 0.5% to 1.0% by weight of the compositions. Especially preferred compositions contain, in addition to magnesium ions, calcium in an amount of from 0.3% to 0.5% by weight.

Description of the invention

The detergent compositions according to the present invention comprise a main surfactant mixture in an amount of from 20% to 50%, preferably from 22% to 40%, by weight of the composition. The mixture comprises from 5% to 95%, by weight of the mixture, of at least one water-soluble anionic surfactant sulfate or sulfonate salt, together with from 95% to 5%, by weight of the mixture, of an N-C8-C16 acyl-N-C1-C4 alkyl glucamine as nonionic surfactant. Preferably, the mixture comprises 20% to 80% of the anionic surfactant and 80% to 20% of the alkyl glucamine, and most preferably 40% to 70% of the anionic surfactant and 60% to 30% of the alkyl glucamine.

The anionic surfactant can be essentially any organic sulfate or sulfonate salt surfactant, but is usually selected from C₁₁-C₁₅ alkylbenzenesulfonates, C₁₀-C₁₆ alkylsulfates and their ethoxy analogues having up to 6 moles of ethylene oxide per mole of alkylethoxysulfate, C₁₃-C₁₈ paraffinsulfonates, C₁₀-C₁₆ olefinsulfonates, C₁₀-C₂₈ alkylglyceryl ethersulfonates, C₁₀-C₁₆ acyl-NC₁-C₄ alkyl or C₂-C₄ hydroxyalkyl glucamine sulfates and mixtures of any of the foregoing. Preferably, the anionic surfactant is selected from Alkyl ethoxysulfates, alkyl glyceryl ether sulfonates and paraffin sulfonates.

Alkylbenzenesulfonates useful in the compositions of the present invention are those wherein the alkyl group, which is substantially linear, has 10 to 16 carbon atoms, preferably 11 to 13 carbon atoms, with a material having an average carbon chain length of 11.8 being most preferred. The phenyl isomer distribution, i.e., the attachment site of the alkyl chain to the benzene nucleus, is not critical, but alkylbenzenes having a high 2-phenyl isomer content are preferred.

Suitable alkyl sulfates are primary alkyl sulfates wherein the alkyl group has 10-16 carbon atoms, more preferably an average of 12-14 carbon atoms, preferably in a linear chain. C₁₀-C₁₆ alcohols derived from natural fats or from the Ziegler olefin build-up or OXO synthesis provide suitable sources of the alkyl group. Examples of synthetically derived materials include Dobanol 23 (Registered Trade Mark) which is available from Shell Chemicals (GB) Ltd. sold by Ethyl Corporation, a mixture of C13-C15 alcohols in the ratio of 67% C13, 33% C15 sold under the trade name Lutensol by BASF GmbH, and Synperonic (registered trademark) by ICI Ltd., and Lial 125 sold by Liquichimica Italiana. Examples of naturally occurring materials from which the alcohols can be obtained are coconut oil and palm kernel oil and the corresponding fatty acids.

Alkyl ethoxysulfate surfactants comprise a primary alkyl ethoxysulfate derived from the condensation product of a C10-C16 alcohol having an average of up to 6 ethylene oxide groups. The C10-C16 alcohol itself can be obtained from any of the sources described above for the alkyl sulfate component. C12-C13 alkyl ether sulfates are preferred.

Conventional base-catalyzed ethoxylation processes to obtain an average degree of ethoxylation of 6 lead to a distribution of individual ethoxylates with 1 to 15 ethoxy groups per mole of alcohol, so that the desired average can be obtained in a variety of ways. Mixtures of materials having different degrees of ethoxylation and/or different ethoxylate distributions resulting from the particular ethoxylation processes employed and the subsequent processing steps such as distillation can be prepared. For example, it has been found that foaming and grease removal performance equivalent to that obtained by a mixture of alkyl sulfate and alkyl triethoxy ether sulfate can be achieved by reducing the amount of alkyl sulfate and using an alkyl ether sulfate having an average of about 2 ethoxy groups per mole of alcohol. In preferred compositions according to the present invention, a mixture of alkyl ethoxy sulfates is used, combining material having an average degree of ethoxylation of from 0.4 to 1.0, more preferably about 0.8, with material having an average degree of ethoxylation of from 2.0 to 4.0, more preferably about 3.0.

Secondary alkane sulfonates useful in the present invention have from 13 to 18 carbon atoms per molecule, more desirably from 13 to 15 atoms per molecule. These sulfonates are preferably prepared by subjecting a paraffin cut corresponding to the chain lengths given above to the action of sulfur dioxide and oxygen according to the well known sulfoxidation process. The product of this reaction is a secondary sulfonic acid which is then neutralized with a suitable base to give a water-soluble secondary alkyl sulfonate. Similar secondary alkyl sulfonates can be obtained by other processes, for example by the sulfochlorination process in which chlorine and sulfur dioxide are reacted with paraffins under irradiation and the resulting sulfonyl chlorides are hydrolyzed and neutralized to form the secondary alkyl sulfonates. Regardless of the process used, it is usually desirable to produce the sulfonate as a monosulfonate, in which no or only a limited amount of unreacted starting hydrocarbon is present and no or only a small amount of inorganic salt is present as a by-product. Similarly, the amounts of disulfonate or higher sulfonated material, but some amount may be present. The monosulfonate may be terminally sulfonated, or the sulfonate group may be attached to the No. 2 carbon or to another carbon of the linear chain. Similarly, any disulfonate present, which is usually obtained when an excess of sulfonating agent is present, may have sulfonate groups distributed over various carbon atoms of the paraffin base, and mixtures of the monosulfonates and disulfonates may be present.

Mixtures of monoalkanesulfonates wherein the alkanes have 14 and 15 carbon atoms are particularly preferred, with the sulfonates being present in a weight ratio in the range of 1:3 to 3:1, based on the C₁₄-C₁₅ paraffins.

Olefin sulfonates useful in the present invention are mixtures of alkene-1-sulfonates, alkene hydroxysulfonates, alkene disulfonates and hydroxydisulfonates and are described in commonly assigned U.S. Patent No. 3,332,880, issued to P.F. Pflaumer & A. Kessler on July 25, 1967.

Suitable alkyl glyceryl ether sulfonates are those which are derived from ethers of coconut oil and tallow.

Other sulfate surfactants include the N-C9-C17 acyl-N-C1-C4 alkyl glucamine sulfates, preferably those wherein the C9-C17 acyl group is derived from coconut or palm kernel oil. These materials can be prepared by the process described in US-A-2,717,894.

The counterion for the anionic surfactant component can be any of sodium, potassium, magnesium, ammonium or alkanolammonium ions or a mixture thereof. For liquid compositions of the invention, sodium is the preferred counterion, but potassium is preferred over sodium when it is important that the compositions of the invention be completely clear and have a high resistance to the formation of a precipitate.

In gel compositions of the invention, sodium is preferred over potassium or ammonium for forming a gel. Preferred liquid detergent compositions according to the invention have a cloud point below 8ºC, preferably below 5ºC, and are at least partially neutralized by ammonium ions.

When calcium and/or magnesium ions are present, they may be introduced either as the oxide or hydroxide to neutralize the surfactant acid or they may be added to the composition as a water-soluble salt. However, the addition of significant amounts of such salts to dishwashing compositions according to the invention increases the temperature at which inorganic salt crystals form in the compositions upon cooling and the amount added in this way should therefore be minimized.

In preferred compositions according to the invention, mixtures of calcium and magnesium ions may be added to provide up to 1% by weight of the composition of Ca++, more preferably from 0.3% to 0.5% by weight of Ca++, and up to 1.50% by weight of the composition of Mg++, more preferably from 0.5% to 1.0% by weight. The preferred mixtures are rich in magnesium and more preferably provide a weight ratio of Ca++ to Mg++ of from 1:1 to 1:4. Compositions wherein Mg++ and/or Ca++ are particularly valuable under conditions of very low water hardness (< 2º Clark hardness) and also at product concentrations of more than 0.5% by weight.

The second main surfactant component of the builder-free liquid compositions of the invention is a compound of the general formula

formed, wherein Z is a polyhydroxyhydrocarbon radical having a linear hydrocarbon chain with at least three hydroxy groups directly attached to the chain, which radical is derived from glucose and mixtures thereof with maltose, wherein the maltose does not represent more than 33% by weight of the mixture, R represents a saturated or unsaturated aliphatic group having 8 to 16 carbon atoms or a mixture of such groups, and R1 represents a C1-C4 alkyl or C2-C4 hydroxyalkyl group.

R can be obtained from any of the sources of hydrocarbon groups discussed hereinabove with reference to the anionic surfactant, but is preferably of natural origin. Preferably, R has an average chain length of 12 to 14 carbon atoms and is obtained from coconut oil or palm kernel oil. R1 preferably represents a methyl group.

The synthesis of glucamine compounds is known in the art and does not form part of the present invention. As stated hereinabove, an exemplary process for preparing N-alkanoyl-N-alkylglucamines is described in US-A-2,703,798, which process comprises two main steps. The first step involves reacting glucose with a primary alkylamine in the presence of hydrogen and a hydrogenation catalyst under elevated temperature and pressure to form a glucamine. This is then reacted with an ester at elevated temperature to produce the N-alkanoyl-N-alkylglucamine. It has been found advantageous to add a small amount of sodium methoxide as a catalyst in this second step.

Preferred amounts of the N-alkanoyl-N-acylglucamine in the liquid and gel compositions of the present invention are from 8 wt% to 25 wt%, more preferably from 9 wt% to 18 wt%, and most preferably from 10 wt% to 15 wt%.

Physically stable compositions according to the invention can be formulated with calcium ions in the absence of magnesium ions, but they require the use of N-alkanoyl-N-alkylglucamines of high purity in which the amounts of unreacted starting materials, impurities and by-products, especially fatty acids, are minimized.

In the broadest aspect of the invention, the balance of the liquid detergent composition may be water or, in the case of a gel composition, a swelling agent and water. However, in preferred compositions, further functional components are included and the combined weights of the anionic surfactant(s) and the glucamine components are in the range of 20 wt% to 40 wt%, more preferably from 22 wt% to 30 wt%.

A highly desirable optional component is one or more foam modifying or enhancing agents, typically present in an individual amount of from 1% to 8% by weight of the composition.

Certain of these materials also have additional functional value, e.g., as soil suspending agents. One such foam-promoting agent is a C10-C16 alkyl mono- or di-C2-C3 alkanolamide, examples of which include coconut alkyl monoethanolamide, coconut alkyl diethanolamide, and palm kernel and coconut alkyl mono- and diisopropanolamides. The palm kernel or coconut alkyl moiety can be either "full cut," including the C10 and C16 fractions, or it can be formed from the so-called "narrow cut" C12-C14 fraction. Synthetic sources of the C₁₀-C₁₆ alkyl group can also be used.

Another useful foam-promoting agent is a zwitterionic surfactant of the general formula

wherein R₁ is C₁₀-C₁₆-alkyl, R₂ is C₁-C₃-alkyl,

R₃ represents a -(CH₂)₃ group or a -(CH₂- -CH₂) group ,

Y - - -(CH₂)₃- means,

n and m are 0 or 1 and X⁻ is CH₂COO⁻ or SO₃; with the proviso that when X⁻ is CH₂COO⁻, m is zero and when X⁻ is SO₃, n is zero and m is 1.

More preferably, R₁ has an average carbon chain length of 12 to 16 carbon atoms and can be obtained from synthetic sources, in which case the chain has a may have some branching, or be obtained from natural fats and oils, in which case the chains are linear and may comprise small amounts of C8 -C10 and C14 -C18 residues. Synthetic sources for the R1 group may be the same as those previously mentioned for the alkyl group in the anionic surfactant component.

Another class of foam promoters useful in the invention are the amine oxides of the general formula R1R2R3NTO, wherein R1 is an alkyl group having 10 to 16 carbon atoms and R2 and R3 are each independently selected from C1-C2 alkyl and C2-C3 hydroxyalkyl groups. Preferred members of this class include dimethyldodecylamine oxide, dimethyltetradecylamine oxide, bis-(2-hydroxyethyl)dodecylamine oxide, and analogs thereof wherein the dodecyl or tetradecyl moiety is derived from natural sources such as coconut or palm kernel oil.

A preferred foam modifying agent is formed from an ethoxylated alcohol or from a mixture of ethoxylated alcohols of defined structure.

The ethoxylated alcohol comprises an ethoxylate of a C6-C13 aliphatic alcohol having an average of 1.5 to 25, more preferably 2 to 5, and most preferably 6 to 10 moles of ethylene oxide per mole of alcohol. The ethoxylate of the aliphatic alcohol contains no more than 1% by weight of non-ethoxylated alcohol when the ethoxylated alcohol has an average of less than 8 moles of ethylene oxide and no more than 2% by weight of non-ethoxylated alcohol when the ethoxylated alcohol has an average of 8 to 25 moles of ethylene oxide per mole of alcohol.

The starting alcohol may be a primary or secondary alcohol, but it is preferably a primary alcohol, which can be obtained from natural or synthetic sources. Thus, natural fats or oils or products of Ziegler olefin building reactions or OXO synthesis can all be used as a source of the hydrocarbon chain, the structure of which can be of the linear or branched type.

The preferred alcohol chain length range is from C₉ to C₁₁, since it has been found that the foam volume and Performance of the compositions according to the invention is optimal when ethoxylates prepared from such alcohols are incorporated. For performance reasons it is also desirable that the hydrophile-lipophile balance (HLB) of the ethoxylated alcohol is in the range of 8.0 to 17.0, more preferably 11.0 to 17.0 and most preferably 11.0 to 15.0. A preferred alcohol ethoxylate is an ethoxylate of a primary alcohol containing an average of 10 carbon atoms in the alkyl chain condensed with an average of 8 ethylene oxide groups per mole of alcohol.

As discussed in relation to the alkyl ethoxy sulfate as anionic surfactant component, the usual (base catalyzed) ethoxylation process to produce an average degree of ethoxylation Eav of 6 results in a distribution of ethoxylates ranging from 1 to 15 moles of ethylene oxide per mole of alcohol. An increase in Eav causes some change in this distribution, mainly a reduction in the amount of non-ethoxylated material, but an increase in Eav from 3 to 5 will still result in approximately 5-10% of such material in the ethoxylated product.

In the liquid dishwashing detergent compositions of the invention, this amount of non-ethoxylated material will cause phase stability/cloud point problems and/or will result in a product with a fatty alcohol odor which is unacceptable to consumers and cannot be masked by conventional detergent perfumes. It has been found that the maximum amount of non-ethoxylated alcohol which can be tolerated in the ethoxylated alcohol component is 1% by weight. More preferably, the amount of non-ethoxylated alcohol is not more than 0.7% and most preferably it is less than 0.5% by weight of the ethoxylated alcohol component.

Distillation under vacuum is used to remove the undesirable material and thereby also removes a portion of the monoethoxylate fraction, thereby increasing the Eav of the remaining material. In preferred embodiments of the invention, the amount of monoethoxylate is not more than 5% by weight of the ethoxylated alcohol.

In preferred compositions according to the invention, combinations of the foam modifying or promoting agents are used, each present in amounts of from 1% to 10%, more preferably from 2% to 8% by weight. One such preferred combination consists of a C12-C14 alkyl dimethyl betaine and a C9-C11 alcohol condensed with an average of 7 to 9 ethylene oxide per mole of alcohol, each material being present in an amount of from 2% to 8% by weight of the composition.

In preferred compositions, the remainder of the formulation comprises a hydrotrope-water system, wherein the hydrotrope may be urea, a C1-C3 aliphatic alcohol, a lower alkyl or dialkyl benzene sulfonate salt such as toluene sulfonate, xylene sulfonate or cumene sulfonate, or a mixture of any of these materials. Conventionally, a single hydrotrope will be sufficient to provide the required phase stability, but in compositions according to the present invention, a mixture such as urea-alcohol-water, alcohol-lower alkyl benzene sulfonate-water or urea-lower alkyl benzene sulfonate-water is preferably employed to achieve the desired viscosity and to keep the compositions stable and easily pourable. For compositions having an active organic material concentration of less than about 40% by weight, the preferred alcoholic hydrotrope is ethanol, which is employed in amounts of from 3% to 10%, preferably from 4% to 8% by weight of the composition, usually in admixture with urea. For compositions having an active organic material concentration of greater than about 40% by weight, mixtures of ethanol with urea and/or lower alkyl benzoic sulfonates are preferred. Mixtures of hydrotropes may, of course, be employed for reasons of cost effectiveness, regardless of any considerations of stability or viscosity.

Optional ingredients of the liquid detergent compositions of the invention include opacifiers such as ethylene glycol distearate, thickeners such as guar gum, antibacterial agents such as glutaraldehyde and Bronopol (registered trademark), Anti-fogging agents such as benzoxytriazole, heavy metal chelating agents such as ETDA or ETDMP, perfumes and dyes. The pH of the compositions may be anywhere within the range of 6.0 to 8.5, but the compositions typically have a pH in the range of 6.5 to 7.3 after manufacture and are subjected to a final pH adjustment processing step to achieve the desired pH of the finished product. For colored products, the pH is preferably in the range of 6.5 to 7.2 to maintain color stability.

The compositions of the invention can be prepared in a variety of ways, but it is preferred that any zwitterionic surfactant contained therein be incorporated towards the end of the manufacturing process, if it is not actually the last ingredient to be added. This will minimize the risk of any decomposition of the zwitterionic surfactant under the acidic conditions prevailing at the beginning of the manufacturing process and will also facilitate control of the viscosity of the finished product. The glucamine surfactant should not be exposed to a pH of less than 4 or more than 10 to prevent hydrolysis of the surfactant.

The anionic surfactant(s) may therefore be prepared as aqueous solutions of alkaline metal or ammonium salts with a pH adjusted between 4 and 10, which are then mixed together with the N-alkanoyl-N-alkylglucamine, followed by any ethoxylated nonionic surfactant and other foam-promoting agent(s) and the hydrotrope, after which any calcium or magnesium ion may be introduced as a water-soluble salt, such as chloride or sulfate. Any zwitterionic surfactant and minor ingredients are then added simultaneously with the pH and viscosity adjustment. This process has the advantage of using conventional techniques and equipment, but results in the introduction of additional chloride or Sulfate ions, which can increase the cloud point temperature (the temperature at which inorganic salts precipitate as crystals in the liquid).

In preferred compositions containing an alkyl ethoxysulfate as the anionic surfactant, the desired alcohol and alcohol ethoxylate can be mixed together and a single sulfation and neutralization of these two materials can then be carried out. To this end, the alcohol and alcohol ethoxylate should be mixed in a weight ratio ranging from 4:3 to 1:6. In the most preferred process, however, a single alcohol ethoxylate feedstock is prepared wherein the amounts of alcohol and ethoxylated alcohol species are controlled to ensure the desired ratio of these feedstocks.

Any of the conventional sulfonating agents such as sulfur trioxide or chlorosulfonic acid may be used to sulfate (sulfonate) the alcohol and alcohol ethoxylate. Neutralization of the alkyl ether sulfuric acid and alkyl sulfuric acid is then carried out with the appropriate alkali or with a magnesium, calcium or magnesium/calcium oxide or hydroxide slurry. If the amount of anionic surfactant is insufficient to allow all of the desired Ca++ and Mg++ ions to be added in this manner, the remainder may then be added in the form of a water-soluble salt.

Gel compositions of the present invention can be prepared using the general procedure described in U.S. Patent No. 4,615,819.

The compositions according to the invention are characterized by a low interfacial tension (IFT) which is an indication of the ability to emulsify greasy and oily soils, a high weight loss in the polypropylene cup test (PPC test) which shows the ability to remove greasy soils from surfaces and to suspend the soil in solution, and at the same time an improved mildness towards the skin. This combination is not usually observed in liquid detergent compositions. Furthermore, the compositions according to the invention show superior foaming performance in both hard and soft water compared to compositions which are prior art.

The test procedures used to determine these parameters are described below.

1) Interfacial tension (IFT)

The measurement of the IFT provides an indication of the ability of a surfactant sample to emulsify soil under defined conditions. The IFT was determined using a spinning drop tensiometer and a University of Texas Model 500 device manufactured by the University of Texas, Austin, Texas, USA. Two instruments were used, namely a model SITE 04, manufactured by Krüss GmbH Wissenschaftliche Laborgeräte, Borsteler Chaussee 85-99a, D-2000 Hamburg 61, BRD, under conditions representative of those encountered in practice in manual dishwashing in Europe. The measurements were therefore carried out at a sample temperature of 48ºC + 1ºC, using a product concentration of 0.12% w/w in water of either 20 Clark mineral hardness or 18º Clark mineral hardness with a Ca:Mg ratio of 3:1 on a molar basis. The soil used was triolein of 99.7% purity (the remaining 0.3% comprises mixed free fatty acids) supplied by the ALDRICH Chemical Company Ltd., New Road, Gillingham, Dorset, England. The results were expressed in Pa cm (1 Pa cm = 10 dyn/cm).

2) Polypropylene Cup Weight Loss (PPC) The Polypropylene Cup Test Method determines the ability of a product to treat total grease under conditions that are similar to those encountered in real-life manual dishwashing. The test involves measuring the amount of solid fat removed from the bottom of a polypropylene cup at a specified temperature, which is lower than that at which the fat melts.

A greasy stain is made by preparing a mixture of the following fats:

70% solid 100% vegetable oil (Spry CRISP'N'DRY, manufactured by Van den Berghs, Burgess Hill, W. Sussex, England)

30% liquid 100% corn oil (MAZZOLA, manufactured by CPC (UK) Ltd., Claygate House, Esher, Surrey, England)

The mixture is heated until it becomes miscible, after which it is cooled and stored at a temperature < 0ºC. For use, approximately 150 ml of fat is melted in a beaker and kept at 70-75ºC. Fifteen clean, dry TRIPOUR polypropylene beakers with a capacity of 250 ml are weighed and 6.00 ± 0.03 g of fat is weighed into each beaker, which is emptied directly onto the bottom of the beaker, without spilling onto the sides. The beakers are kept horizontal and the fat is allowed to solidify for 2-3 hours at a constant room temperature of 21 ± 1ºC.

A 0.12% solution of the test product is prepared at 50-55ºC and 100 10.1 g are added to each of five glass vessels, which are then closed with a lid. The closed vessels are placed in a water bath located in a constant temperature room, the temperature of which is set at 45-46ºC, so that the solution in each vessel has a temperature of 43.8 ± 0.1ºC. A similar procedure is carried out both for each product to be tested and for the standard product with which the test products are compared.

The contents of a vessel are then emptied down the side into a beaker, taking care not to disturb the fat at the bottom, and the vessel is kept horizontal at 21ºC for half an hour before being transferred to an ice bath and kept there for 10 minutes. As the solution cools, a rim of fat deposits forms on the surface of the beaker. This sequence of emptying and cooling is repeated for each beaker-vessel combination. After 10 minutes, each beaker is quickly emptied and the interior of the beaker is dried to remove all material that is on the beaker walls between the rim and the level of the fat ring. The The cups are then placed upside down on an absorbent kitchen roll to drain for 10-15 minutes before being dried in an oven for 2 hours at 30ºC followed by a further hour at 50ºC. The cups are then weighed again. An average weight difference between the original weight of the fat and that remaining after the test is calculated for the five samples. This difference is divided by the weight difference obtained using the standard product to give a value expressing the performance ratio between the test products and the standard products. The products according to the invention show a performance ratio of more than about 1.3, preferably of at least about 1.4.

For the purposes of the test, the standard product should demonstrate grease handling performance in the same general area as the product being tested at the same concentration. This can be achieved by adjusting the weight ratio of the liquid to the solid grease serving as the soil composition so that the standard product (the reference) provides 20-35% grease removal under the conditions of the test, while the test product may provide 20-80% grease removal. The same batch of grease must be used for the test and the reference products.

3) Total foam and foam performance

Total foam is the total volume of foam generated during a standard dishwashing test and represents a measure of the achieved foaming ability of the formulation. Foam performance is a measure of the soil load required to reduce the foam of a test solution to a defined minimum under standard conditions of product concentration, temperature and water hardness. It reflects the achieved useful application time of a manual dishwashing solution. The foam performance of the compositions under identical test conditions was determined using a prepared mixed food soil and a prepared greasy soil in the mechanical foaming test procedure described.

Test conditions

Product concentration 0.12%

Water temperature 48ºC

Water hardness 20 Clark hardness and 180 Clark hardness

Mixed food dirt Rice/Minced Meat/Egg "actual menu"

1 x 392g can Tyne Brand minced beef and onion¹

1 x 439 g can Ambrosia foamy rice pudding²

1 egg

25 ml 2% mixed free fatty acid (MFFA) in corn oil*

25 ml corn oil

Greasy dirt Baking mix slurry

30 g sponge cake mix³

60 g 2% MFFA in corn oil*

1 Distributed by Master Foods, Kings Lynn, Norfolk, England.

2 Distributed by Ambrosia Creamery, Lifton, Devon, England.

3 Distributed by McDougalls Catering Foods Ltd., Imperial Way, Warton Grange, Reading, England.

* 4 g oleic acid, 4 g linoleic acid, 2 g stearic acid, 5 g palmitic acid, 735 g pure corn oil.

Test procedure

The method uses 4 cylinders with a length of 30 cm and a diameter of 10 cm, fixed side by side and rotating around a central axis at a speed of 24 rpm. Each cylinder is loaded with 500 ml of product solution with a concentration of 0.12% and a temperature of 48ºC. The outer two cylinders are used for one of the products to be compared and the inner two for the other product.

The cylinders are rotated for 2 min, stopped, the initial foam is measured and a soil load is then added, typically in 2 ml aliquots. After 1 min, the cylinders are rotated again and rotated for 1 min. The foam height is noted and 2 ml of soil is added to each cylinder. After 1 min, the cylinders are rotated again. This process is continued until the foam height in the cylinder is less than 0.6 cm.

The sum of all foam height measurements in each test (i.e., until the foam height becomes less than 0.6 cm) represents the total foam measurement.

One product is designated as the control and the Foam Index and Foam Performance numbers are calculated for the other products against the "Control Product" on the following basis.

Foam index of the test product

= Total foam of the test product/Total foam of the control product x 100

Foam performance of the test product

= Number of dirt additions to the test product solution to reduce the foam height to 0.6 cm /Number of dirt additions to the control product to reduce the foam height to 0.6 cm x 100

The invention is illustrated by the following non-limiting examples in which all parts and percentages are by weight unless otherwise indicated.

example 1

A range of surfactant master systems were prepared containing a mixture of an alkyl ethoxy sulfate surfactant and N-lauroyl-N-methylglucamine. The alkyl ethoxy sulfate was obtained from a C12-C14 primary alcohol which was condensed with an average of 0.8 moles of ethylene oxide per mole of alcohol and neutralized with a mixture of ammonium and magnesium ions to contain 0.22 moles of magnesium per mole of alkyl ethoxy sulfate. A simulated product was first prepared with a 30% concentration of surfactant master in distilled water. A 0.12 wt.% solution of this product was then prepared in either soft (20 Clark hardness) or hard (180 Clark hardness) water and tested for IFT. and in water of 2º Clark hardness for the removal of greasy soil in the PPC test using the above test procedures. This procedure was carried out for alkyl ethoxy sulfate to alkyl glucamine ratios of 100:0, 75:25, 65:35, 50:50, 25:75 and 0:100 and the results are shown below. Weight ratio of AES:GA water hardness

It can be seen that the addition of alkylglucamine to the anionic surfactant produces a remarkable improvement in fat emulsification as shown by the TFT values and in the handling of greasy soil as shown by the increased soil removal values in PPC test.

The above co-surfactant blends were also evaluated for total foam height and foam performance using the test procedures described above. However, the results were not indexed to a standard product but reported directly as total foam values/foam performance values. Weight ratio of AES:GA hardness 2º Clark "actual menu" dirt greasy dirt 18º Clark "actual menu" dirt

By considering the greasy soil removal data and the foaming data under greasy soil loading conditions simultaneously, it can be seen that a preferred range of blends for both grease removal and foam performance is alkyl ethoxysulfate:alkylglucamine from 75:25 to alkyl ethoxysulfate:alkylglucamine from 50:50, with an optimum at about 65:35. A 100% alkylglucamine system gives comparable grease removal performance, but is seriously disadvantaged in overall foam and foam performance, particularly under greasy soil loading conditions.

Example 2

The following compositions A-E were prepared:

Composition A represents a comparable commercially available liquid detergent dishwashing product, whereas compositions B, C, D and E are according to the invention. Linear C11,8-alkylbenzenesulfonate N-coconut alkanoyl-N-methylglucamine C12-13-alkyl(EO)0,8-sulfate C12-13-alkyl(EO)0,8-sulfate Ethoxylate of a primary alcohol¹ Mg++ ion C12-14-alkyldimethylbetaine Coconut monoethanolamide C12-14-alkyldimethylamine oxide Sodium cumenesulfonate Ethanol Urea Water to 100¹ A predominantly linear C9-C11 mixture containing an average of 10 ethylene oxide units per mole of alcohol and less than 2 wt.% non-ethoxylated alcohol.

The IFT, PPC and foam performance values were determined for all five products and the results are shown below Clark Hardness Total Foam/Foam Performance Mixed Dirt Greasy dirt Clark hardness

Claims (15)

1. Builder-free, liquid or gel detergent composition in the form of a physically stable aqueous solution comprising 20% to 50% by weight of the composition of a surfactant main mixture which, based on the weight of the mixture, a) 5% to 95% of at least one water-soluble anionic surfactant sulfate or sulfonate salt; b) 95% to 5%, based on the weight of the mixture, of one or more compounds of the general formula wherein Z is a polyhydroxyhydrocarbon radical having a linear hydrocarbon chain with at least 3 hydroxy groups directly attached to the chain, which radical is derived from glucose and mixtures thereof with maltose, wherein the maltose represents not more than 33% by weight of the mixture, R represents a saturated or unsaturated alkyl group having 8 to 16 carbon atoms or a mixture of such groups and R₁ represents a C₁-C₄ alkyl or C₂-C₄ hydroxyalkyl group; wherein a 0.12 wt.% aqueous solution of the surfactant mixture of the said composition in water of Clark mineral hardness (Ca:Mg ratio 3:1) and a temperature of 48ºC (i) a spinning drop interfacial tension (IFT) of less than 0.2 Pa.cm using a triolein soil of 99.7% purity; (ii) has a greasy soil removal value in the Polypropylene Cup (PPC) test of more than 1,3 times the value obtained in the same test under the same conditions using a 0,12% solution of the anionic surfactant component(s) only. 2. Builder-free, liquid or gel detergent composition according to claim 1, wherein the polyhydroxyhydrocarbon radical of component b) is selected from glucose and mixtures derived therefrom with maltose, wherein the maltose comprises not more than 25% by weight of the mixture. 3. A builder-free liquid or gel detergent composition according to any one of claims 1 and 2 comprising 22% to 40% of the main surfactant mixture. 4. A builder-free liquid or gel detergent composition according to any one of claims 1 to 3, wherein the main surfactant mixture comprises 20% to 80% of (a) and 80% to 20% of (b), more preferably 40% to 70% of (a) and 60% to 30% of (b). 5. Builder-free, liquid or gel detergent composition according to any one of claims 1 to 4, wherein component a) is selected from C₁₀-C₁₆ alkyl ethoxy sulfates containing up to an average of 6 moles of ethylene oxide per mole of alkyl ethoxy sulfate, C₁₀-C₁₈ alkyl glyceryl ether sulfonates, C₁₀-C₁₆ paraffin sulfonates, C₁₀-C₁₆ acyl-N-C₁-C₄ alkyl glucamine sulfates and mixtures thereof. 6. A builder-free, liquid or gel detergent composition according to any one of claims 1 to 5, wherein component a) comprises a primary C₁₂-C₁₄ alkyl ethoxy sulfate as a surfactant having not more than an average of 1.5 ethoxy groups per mole of alkyl ethoxy sulfate, preferably in the range of an average of 0.4 to 1.0 groups per mole of alkyl ethoxy sulfate. 7. A builder-free liquid or gel detergent composition according to any one of claims 1 to 6, which contains Mg⁺⁺ in an amount of up to 1.5% by weight, preferably from 0.5% to 1#0% by weight of the composition. 8. Builder-free, liquid or gel-like composition according to claim 7, which contains Ca⁺⁺ in an amount of up to 1% by weight of the composition, preferably from 0.3% to 0.5% by weight. 9. A builder-free liquid or gel detergent composition according to any one of claims 1 to 8, which contains one or more foam-promoting materials, each present in an amount of from 1% to 8% by weight of the composition. 10. Builder-free liquid or gel detergent composition according to claim 9, wherein the foam-promoting material is selected from C₁₀-C₁₆ alkyl mono- or di-C₂-C₃ alkanolamides, C₁₂-C₁₆ alkyl or alkylamidobetaines, C₁₂-C₁₆ alkylsulfobetaines, C₁₀-C₁₆ alkyl, di-C₁₋₄ alkyl or di-C₁₋₄ hydroxyalkylamine oxides, ethoxylates of C₄-C₁₆ primary alcohol having an average of 7 to 12 ethylene oxide groups per mole of alcohol and mixtures thereof. 11. An unbuilt liquid detergent composition according to any of claims 9 or 10 comprising a combination of a C₁₂-C₁₄ alkyl dimethyl betaine and a C₉-C₁₁₁ primary alcohol condensed with an average of 7 to 9 moles of ethylene oxide per mole of alcohol, each material being present in an amount of from 2% to 8% by weight of the composition. 12. A builder-free liquid detergent composition according to any preceding claim, further comprising a hydrotrope selected from urea, a C1-C3 aliphatic alcohol, a lower alkyl or dialkyl benzene sulfonate, or a mixture of any of these. 13. A builder-free liquid dishwashing detergent composition according to any preceding claim having a cloud point of not more than 8°C, preferably less than 5°C. 14. A physically stable, builder-free, liquid dishwashing detergent composition according to any preceding claim, wherein the composition comprises an opacifying agent. 15. Builder-free, liquid or gel detergent composition according to any one of the preceding claims having a pH in the range of 6.0 to 8.5.