EP0550636B1

EP0550636B1 - Liquid detergent compositions

Info

Publication number: EP0550636B1
Application number: EP91918093A
Authority: EP
Inventors: Julie Anne Dyet; Peter Robert Foley
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1990-09-28
Filing date: 1991-09-25
Publication date: 1995-09-13
Anticipated expiration: 2011-09-25
Also published as: AU8735291A; SK25393A3; EG19516A; CZ281716B6; DE69113055T2; AU664023B2; IN185274B; CA2092194A1; EP0550636A1; IE76141B1; MA22303A1; HUT64390A; WO1992006171A1; BR9106935A; AR244328A1; GB9021217D0; NZ240022A; PT99087B; TR26013A; HU213448B

Abstract

Aqueous unbuilt liquid or gel-form detergent compositions are provided comprising, from 15 % to 65 % by weight of a core surfactant mixture, comprising from 5 % to 95 % by weight of the mixture of a water soluble anionic sulphate or sulphonate surfactant salt together and from 5 % to 95 % by weight of the mixture of one or more compounds of formula (I), wherein Z is a polyhydroxy hydrocarbyl moiety having a linear hydrocarbyl chain with at least three hydroxy groups connected directly to the chain, said moiety being derived from glucose and mixtures thereof with maltose, the maltose comprising not more than 33 % of the mixture, R is a C6-C16 hydrocarbyl radical and R1 is a C1-C4 alkyl or C2-C4 hydroxyalkyl group, a 0.12 % solution of the surfactant mixtures of the compositions having an interfacial tension (IFT) of less than 0.2 Pa.cm at 48 °C and a polypropylene cup (PPC) greasy soil removal value of at least 1.4 x that of the anionic surfactant component(s) alone. Preferred optional ingredients include amide, betaine and ethoxylated C9-C11 fatty alcohol suds modifiers.

Description

Field of Invention

This invention relates generally to aqueous liquid detergent compositions and more particularly to liquid detergent compositions intended to remove soils of a largely greasy nature from hard surfaces such as dishes and other articles used in food preparation and consumption.

Background of the Invention

Liquid detergent compositions intended for use as dishwashing products conventionally take the form of aqueous solutions containing a mixture of one or more sulphate and sulphonate anionic detergents as 'core' surfactant materials together with a suds promoting or stabilising agent. The suds stabilisation agent can take a number of forms but is normally an amide derivative, an amine oxide, an ethoxylated aliphatic alcohol, a zwitterionic surfactant such as a betaine, or a mixture of several of these. Usage levels of these types of materials are conventionally in the range of 2-8% normally 3-5% by weight of the composition.
One group of amide derivatives that have been suggested for suds promoting and stabilising purposes are the N-alkanoyl N-alkyl glucamines. These materials are derived from glucose and can be prepared by reacting a lower alkylamine with glucose to form a glucamine and then treating this with a methyl ester of a fatty acid of the required chain length to give the N-alkanoyl-N-alkyl glucamine.
Compounds of this type are taught in e.g. US-A-2703798, WO83/04412, EP-A-285,768 and GB-A-809060. EP-A-285,768 discloses the use of N-polyhydroxyalkyl fatty acid amides as thickening agents for liquid aqueous surfactant systems. GB-A-809060 discloses detergent compositions comprising at least one water soluble salt of an organic sulphuric reaction product having in its molecular structure a sulphuric acid or a sulphonic acid radical and an amide derivative of the above type in an amount of from 5% to 60% by weight of the water soluble organic sulphuric reaction product. The amide derivatives are stated to provide an improvement in the sudsing characteristics 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. Whilst the patent envisages that the surfactant combination can be used alone, the preferred and exemplified embodiments are granular products incorporating phosphate builder and sodium sulphate filler.
The Applicants have now discovered that unbuilt liquid or gel-form detergent compositions containing, as core surfactants, combinations of certain N-alkanoyl -N-alkyl glucamines with sulphated or sulphonated surfactants, provide a significant improvement in the removal of greasy soils from hard surfaces together with superior sudsing mileage performance and appreciable skin mildness benefits relative to known products. Although mixtures of anionic sulphate or sulphonate surfactants and N-alkanoyl -N-alkyl glucamines have been proposed as a means of obtaining improvements in the sudsing of built products at low wash temperatures, the performance aspects of greasy soil removal and skin mildness properties that have how been found for the mixtures have, hitherto, not been recognised.
Therefore, according to the present invention, there is provided an unbuilt liquid or gel-form detergent composition in the form of a physically stable aqueous solution comprising from 20 to 50% by weight of the composition of a core surfactant mixture, comprising by weight of the mixture,

a) from 5% to 95% of at least one water-soluble anionic sulphate or sulphonate surfactant salt;
b) from 95% to 5% by weight of the mixture of one or more compounds having the general formula
wherein Z is a polyhydroxy hydrocarboxyl moiety having a linear hydrocarbyl chain with at least three hydroxy groups connected directly to the chain, said moiety being derived from glucose and mixtures thereof with maltose, the maltose comprising not more than 33% by weight of the mixture, R is a saturated or unsaturated aliphatic group of from 8 to 16 carbon atoms or a mixture of such groups and R₁ is a C₁-C₄ alkyl or C₂-C₄ hydroxyalkyl group;
whereby a 0.12% by weight aqueous solution of the surfactant mixture of said composition, in water of 2° Clark mineral hardness (Ca:Mg ratio of 3:1) and temperature of 48°C, has
- i) a spinning drop interfacial tension (IFT) of less than 0.2 Pa cm using a triolein soil of 99.7% purity;
- ii) a greasy soil removal value in the Polypropylene Cup (PPC) Test of at least 1.4 x the value obtained in the same test under the same conditions using a 0.12% solution of the anionic surfactant component(s) alone.

For the purposes of the present invention 'physically stable' is taken to mean the maintenance of a single phase condition, without precipitation, after 3 months storage at a temperature of 21°C. Where the product incorporates an opacifier no, or minimal, settlement of the opacifier should have occurred. Furthermore 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 shall be such as to correspond to the cation(s) in the detergent composition, and where a mixture of cations is present, in the weight proportions in which each cation is present in the mixture.
Preferred compositions in accordance with the invention employ component b) compounds in which the polyhydroxyhydrocarbyl moieties are derived from glucose or mixtures thereof with maltose in which maltose comprises <25% by weight of the mixture. Commercially available technical grade glucose contains maltose as an impurity at a level of up to 5% by weight. For the purposes of the present invention, references hereinafter to glucamines are to be construed as material including up to 5% by weight of the corresponding material derived from maltose.
Suitable anionic sulphate or sulphonate surfactants include C₁₀-C₁₆ alkyl ethoxy sulphates containing an average of up to 6 moles of ethylene oxide per mole of alkyl ethoxysulphate, C₁₀-C₁₈ paraffin sulphonates, and N-C₉-C₁₇ acyl-N-C₁-C₄ alkyl glucamine sulphates.
Useful compositions in accordance with the invention incorporate an anionic surfactant system comprising from 9% to 18% by weight of the composition of a primary C₁₂-C₁₄ alkyl ethoxy sulphate stock containing an average of from 0.4 to 4.0 ethylene oxide groups per mole of C₁₂-C₁₄ alkyl ethoxy sulphate, preferably from 0.3 to 3.0, together with from 9% to 15% by weight of the composition of N-coconut acyl-N-methyl glucamine.
Preferred compositions employ an anionic surfactant to glucamine weight ratio of between 2:1 and 1:1. Particularly preferred compositions contain from 10% to 18% by weight of C₁₂-C₁₄ alkyl ethoxy sulphate and from 7% to 15% by weight of the glucamine surfactant. The alkyl ethoxy sulphates themselves comprise a mixture of material containing an average of approximately 0.8 moles of ethylene oxide/mole and material containing an average of approximately 3.0 moles of ethylene oxide/mole in a weight ratio of between 2:1 and 5:1 preferably approximately 4:1.
Preferably compositions in accordance with the invention also contain 1%-8%, most preferably 2%-7% by weight of a suds booster selected from C₁₀-C₁₆ alkyl mono or di-C₂-C₃ alkanolamides, C₁₂-C₁₄ alkyl or alkyl amido betaines, C₁₂-C₁₄ alkyl sulphobetaines, C₁₀-C₁₆ alkyl di C₁-C₄ alkyl or di C₂-C₄ hydroxyalkyl amine oxides, C₉-C₁₂ primary alcohol ethoxylates containing an average of from 7 to 12 ethylene oxide groups per mole of alcohol and mixtures thereof.
Preferred suds boosters comprised 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⁺⁺, at a level of up to 1.5% more preferably from 0.5% to 1.0% by weight of the compositions. Especially preferred compositions also contain calcium in addition to the magnesium ion at a level of from 0.3% to 0.5% by weight.

Description of the Invention

Detergent compositions in accordance with the present invention comprise a mixture of core surfactants in an amount of from 20% to 50% by weight of the composition, preferably from 22% to 40% by weight. The mixture comprises from 5% to 95% by weight of the mixture of at least one water-soluble anionic sulphate or sulphonate surfactant salt together with from 95% to 5% by weight of the mixture of a N-C₈-C₁₆ acyl-N-C₁-C₄ alkyl glucamine nonionic surfactant. Preferably the mixture comprises from 20% to 80% of the anionic surfactant and from 80% to 20% of the alkyl glucamine, and most preferably from 40% to 70% anionic surfactant and from 60% to 30% alkyl glucamine.
The anionic surfactant can essentially be any organic sulphate or sulphonate surfactant salt but is usually selected from C₁₁-C₁₅ alkyl benzene sulphonates, C₁₀-C₁₆ alkyl sulphates and their ethoxy analogues containing up to six moles of ethylene oxide per mole of alkyl ethoxy sulphate, C₁₃-C₁₈ paraffin sulphonates C₁₀-C₁₆ olefin sulphonates, C₁₀-C₂₀ alkyl glyceryl ether sulphonates, C₉-C₁₇ acyl-N-C₁-C₄ alkyl or C₂-C₄ hydroxyalkyl glucamine sulphates and mixtures of any of the foregoing. Preferably the anionic surfactant is selected from alkyl ethoxy sulphates, alkyl glyceryl ether sulphonates and paraffin sulphonates.
Alkyl benzene sulphonates useful in compositions of the present invention are those in which the alkyl group, which is substantially linear, contains 10-16 carbon atoms, preferably 11-13 carbon atoms, a material with an average carbon chain length of 11.8 being most preferred. The phenyl isomer distribution, i.e. the point of attachment of the alkyl chain to the benzene nucleus, is not critical, but alkyl benzenes having a high 2-phenyl isomer content are preferred.
Suitable alkyl sulphates are primary alkyl sulphates in which the alkyl group contains 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 Ziegler olefin build-up, or OXO synthesis, form suitable sources for the alkyl group. Examples of synthetically derived materials include Dobanol 23 (RTM) sold by Shell Chemicals (UK) Ltd., Ethyl 24 sold by the Ethyl Corporation, a blend of C₁₃-C₁₅ alcohols in the ratio 67% C₁₃, 33% C₁₅ sold under the trade name Lutensol by BASF GmbH and Synperonic (RTM) by ICI Ltd., and Lial 125 sold by Liquichimica Italiana. Examples of naturally occurring materials from which the alcohols can be derived are coconut oil and palm kernel oil and the corresponding fatty acids.
Alkyl ethoxy sulphate surfactants comprise a primary alkyl ethoxy sulphate derived from the condensation product of a C₁₀-C₁₆ alcohol with an average of up to 6 ethylene oxide groups. The C₁₀-C₁₆ alcohol itself can be obtained from any of the sources previously described for the alkyl sulphate component. C₁₂-C₁₃ alkyl ether sulphates are preferred.
Conventional base-catalysed ethoxylation processes to produce an average degree of ethoxylation of 6 result in a distribution of individual ethoxylates ranging from 1 to 15 ethoxy groups per mole of alcohol, so that the desired average can be obtained in a variety of ways. Blends can be made of material having different degrees of ethoxylation and/or different ethoxylate distributions arising from the specific ethoxylation techniques employed and subsequent processing steps such as distillation. For example, it has been found that equivalent sudsing and grease removal performance to that given by a blend of alkyl sulphate and alkyl triethoxy ether sulphate can be obtained by reducing the level of alkyl sulphate and using an alkyl ether sulphate with an average of approximately two ethoxy groups per mole of alcohol. In preferred compositions in accordance with the present invention a mixture of alkyl ethoxy sulphates is used, combining material having an average degree of ethoxylation from 0.4 to 1.0, more preferably approximately 0.8, with material having an average degree of ethoxylation of from 2.0 to 4.0 more preferably approximately 3.0. Secondary alkane sulphonates useful in the present invention have from 13 to 18 carbon atoms per molecule, more desirably 13 to 15 atoms per molecule. These sulphonates are preferably prepared by subjecting a cut of paraffin, corresponding to the chain lengths specified above, to the action of sulphur dioxide and oxygen in accordance with the well-known sulphoxidation process. The product of this reaction is a secondary sulphonic acid which is then neutralized with a suitable base to provide a water-soluble secondary alkyl sulphonate. Similar secondary alkyl sulphonates may be obtained by other methods, e.g. by the sulphochlorination method in which chlorine and sulphur dioxide are reacted with paraffins in the presence of actinic light, the resulting sulphonyl chlorides being hydrolysed and neutralized to form the secondary alkyl sulphonates. Whatever technique is employed, it is normally desirable to produce the sulphonate as the monosulphonate, having no unreacted starting hydrocarbon or having only a limited proportion thereof present and with little or no inorganic salt by-product. Similarly, the proportions of disulphonate or higher sulphonated material will be minimized but some may be present. The monosulphonate may be terminally sulphonated or the sulphonate group may be joined on the 2-carbon or other carbon of the linear chain. Similarly, any accompanying disulphonate, usually produced when an excess of sulphonating agent is present, may have the sulphonate groups distributed over different carbon atoms of the paraffin base, and mixtures of the monosulphonates and disulphonates may be present.
Mixtures of monoalkane sulphonates wherein the alkanes are of 14 and 15 carbon atoms are particularly preferred wherein the sulphonates are present in the weight ratio of C₁₄-C₁₅ paraffins in the range from 1:3 to 3:1.
Olefin sulphonates useful in the present invention are mixtures of alkene-1-sulphonates, alkene hydroxysulphonates, alkene disulphonates and hydroxydisulphonates and are described in the commonly assigned US-A-3332880 issued to P.F. Pflaumer & A. Kessler on July 25 1967.
Suitable alkyl glyceryl ether sulphonates are those derived from ethers of coconut oil and tallow.
Other sulphate surfactants include the N-C₉-C₁₇ acyl-N-C₁-C₄ alkyl glucamine sulphates, preferably those in which the C₉-C₁₇ acyl group is derived from coconut or palm kernel oil. These materials can be prepared by the method disclosed in US-A-2717894.
The counter ion for the anionic surfactant component can be any one of sodium, potassium, magnesium, ammonium or alkanol-ammonium or a mixture thereof. For liquid compositions of the invention, sodium is the preferred counter ion but potassium is preferred over sodium where it is of importance that the compositions of the invention are completely clear and have a high resistance to precipitate formation.
In gel-form compositions of the invention, sodium is preferred over potassium or ammonium for the purposes of forming a gel. Preferred liquid detergent compositions in accordance with the invention have a chill point less than 8°C preferably less than 5°C, and are at least partially neutralised by ammonium ions.
Where calcium and/or magnesium ions are present they can either be introduced as the oxide or hydroxide to neutralise the surfactant acid or can be added to the composition as a water soluble salt. However the addition of appreciable levels of such salts to dishwashing compositions in accordance with the invention raises the temperature at which inorganic salt crystals form in the compositions on cooling and the amount added in this way should therefore be minimised.
In preferred compositions according to the invention, mixtures of calcium and magnesium ions may be added in order to provide up to 1% Ca⁺⁺ by weight of the composition, more preferably from 0.3% to 0.5% Ca⁺⁺ and up to 1.50% Mg⁺⁺, more preferable from 0.5% to 1.0% by weight. The preferred mixtures are rich in magnesium and more preferably provide a Ca⁺⁺:Mg⁺⁺ weight ratio of from 1:1 to 1:4. Compositions incorporating Mg⁺⁺ and/or Ca⁺⁺ are especially valuable for conditions of very low water hardness (<2° Clark) and also for product concentrations greater than 0.5% by weight.
The second core surfactant component of the unbuilt liquid compositions of the invention is a compound of the general formula

wherein Z is a polyhydroxy hydrocarbyl moiety having a linear hydrocarbyl chain with at last three hydroxy groups groups connected directly to the chain, said moiety being derived from glucose and mixtures thereof with maltose, the maltose comprising not more than 33% by weight of the mixture, R is a saturated or unsaturated aliphatic group of from 8 to 16 carbon atoms, or a mixture of such groups, and R₁ is a C₁-C₄ alkyl or C₂-C₄ hydroxyl alkyl group.
R may be derived from any of the sources of hydrocarbyl groups discussed hereinbefore with reference to the anionic surfactant but is preferably natural in origin.
Preferably R has an average chain length of from 12 to 14 carbon atoms and is derived from coconut oil or palm kernel oil. R₁ is preferably a methyl group.
Synthesis of the subject glucamine compounds is known in the art and does not form part of the present invention. As noted hereinbefore, US-A-2703798 discloses a representative process for preparing N-alkanoyl N-alkyl glucamines which process has two principal steps. The first step involves reacting glucose and a primary alkylamine in the presence of hydrogen and a hydrogenation catalyst under elevated temperature and pressure to form glucamine. This is then reacted with an ester at elevated temperature to form the N-alkanoyl -N-alkyl glucamine. It has been found advantageous to add a low level of sodium methoxide as a catalyst in this second step.
Preferred levels of the N-alkanoyl -N-alkyl glucamine in liquid and gel-form compositions of the present invention lie between 8% and 25% by weight, more preferably between 9% and 18% and most preferably between 10% and 15% by weight.
Physically stable compositions in accordance with the invention can be formulated with calcium ions in the absence of magnesium ions, but require the use of N-alkanoyl -N-alkyl glucamines of high purity in which the levels of unreacted starting materials, impurities and by-products, particularly fatty acids, are minimised.
In the broadest aspect of the invention the balance of the liquid detergent composition can be made up by water or, in the case of a gel-form composition by a gelling agent and water. However in preferred compositions, other functional components are also included and the combined weights of the anionic surfactant(s) and glucamine components lie in the range from 20% to 40%, more preferably from 22% to 30% by weight.
A highly desirable optional component is one or more suds modifiers or promoters, normally present at an individual level of from 1% to 8% by weight of the composition.
Certain of these materials also have additional functional value as e.g. soil suspending agents. One such suds promoting agent is a C₁₀-C₁₆ alkyl mono- or di-C₂-C₃ alkanolamide, examples including coconut alkyl monoethanolamide, coconut alkyl diethanolamide and palm kernel and coconut alkyl mono-and di-isopropanol amides. The palm kernel or coconut alkyl residue may either be 'whole cut', including the C₁₀ and C₁₆ fractions or may be the so-called 'narrow-cut' C₁₂-C₁₄ fraction, Synthetic sources of the C₁₀-C₁₆ alkyl group can also be used.
Another useful suds promoting agent is a zwitterionic surfactant of general formula

wherein R₁ is C₁₀-C₁₆ alkyl,
R₂ is C₁-C₃ alkyl,
R₃ is a -(CH₂)₃ group or a

group,
Y is

n & m are O or 1, and
X⁻ is CH₂COO⁻ or SO₃;
provided that where X⁻ is CH₂COO⁻, m is O, and where X⁻ is SO₃, n is O and m is 1.
More preferably R₁ has an average carbon chain length of from 12 to 16 carbon atoms and may be derived from synthetic sources, in which case the chain may incorporate some branching, or from natural fats and oils, in which case the chains are linear and may include minor amounts of C₈-C₁₀ and C₁₄-C₁₈ moieties. Synthetic sources for the R₁ group may be the same as those mentioned previously for the alkyl group in the anionic surfactant component.
A further class of suds promoting agents useful in the invention are the amine oxides of general formula R₁R₂R₃N→O wherein R₁ is an alkyl group containing from 10 to 16 carbon atoms and R₂ and R₃ are each independently selected from C₁-C₃ alkyl and C₂-C₃ hydroxy alkyl groups. Preferred members of this class include dimethyldodecyl amine oxide, dimethyl tetradecyl amine oxide, bis-(2 hydroxyethyl) dodecylamine oxide and analogues thereof in which the dodecyl or tetradecyl moiety is derived from natural sources such as coconut or palm kernel oil.
A preferred suds modifying agent is an ethoxylated alcohol or a mixture of ethoxylated alcohols of defined constitution.
The ethoxylated alcohol comprises a C₆-C₁₃ aliphatic alcohol ethoxylate containing an average of from 1.5 to 25, more preferably from 2 to 15 and most preferably from 6 to 10 moles of ethylene oxide per mole of alcohol. The aliphatic alcohol ethoxylate contains not more than 1% by weight of unethoxylated alcohol where the ethoxylated alcohol contains an average of less than 8 moles of ethylene oxide and not more than 2% by weight of unethoxylated alcohol where the ethoxylated alcohol contains an average of from 8 to 25 moles of ethylene oxide per mole of alcohol.
The starting alcohol may be a primary or secondary alcohol but is preferably a primary alcohol which may be derived from natural or synthetic sources. Thus natural fats or oils, or products of Ziegler olefin build up reactions or OXO synthesis may all be used as the source of the hydrocarbon chain, the structure of which may be linear or branched in type.
The preferred alcohol chain length range is from C₉ to C₁₁ as it has been found that the sudsing volume and mileage performance of compositions in accordance with the invention is optimum when incorporating ethoxylates made from such alcohols. It is also desirable for performance reasons that the hydrophilic-lipophilic balance (HLB) of the ethoxylated alcohol is in the range from 8.0 to 17.0, more preferably from 11.0 to 17.0 and most preferably from 11.0 to 15.0. A preferred alcohol ethoxylate is a primary alcohol ethoxylate 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 with respect to alkyl ethoxy sulphate as the anionic surfactant component, the normal (base catalysed) ethoxylation process to produce an average degree of ethoxylation E_av of 6 results in a distribution of ethoxylate species which ranges from 1 to 15 moles of ethylene oxide per mole of alcohol. An increase in E_av causes some change in this distribution, principally a reduction in the level of unethoxylated material, but an increase in E_av from 3 to 5 will still leave approximately 5-10% of such material in the ethoxylated product.
In the liquid dishwashing detergent compositions of the invention, this level of unethoxylated material will give rise to phase stability/chill point problems and/or will result in a product having a fatty alcohol odour which is unacceptable to consumers and cannot be masked by conventional detergent perfumes. It has been found that the maximum level of unethoxylated alcohol that can be tolerated in the ethoxylated alcohol component is 1% by weight. More preferably the unethoxylated alcohol level is not more than 0.7% and most preferably is less than 0.5% by weight of the ethoxylated alcohol component.
Distillation under vacuum is employed to remove the undesired material and this also removes a portion of the monoethoxylate fraction, thereby increasing the E_av of the remaining material. In preferred embodiments of the invention the level of monoethoxylate is not more than 5% by weight of the ethoxylated alcohol.
In preferred compositions in accordance with the invention, combinations of the suds modifiers or promoters are used, each being present at a level of from 1% to 10% more preferably from 2% to 8% by weight. One such preferred combination is a C₁₂-C₁₄ alkyl dimethyl betaine and a C₉-C₁₁ alcohol condensed with an average of from 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.
In preferred compositions the balance of the formula comprises a hydrotrope-water system in which the hydrotrope may be urea, a C₁-C₃ aliphatic alcohol, a lower alkyl or dialkyl benzene sulphonate salt such as toluene sulphonate, xylene sulphonate, or cumene sulphonate, or mixtures of any of these. Normally a single hydrotrope will be adequate to provide the required phase stability, but compositions in accordance with the present invention preferably employ a mixture such as urea-alcohol-water, alcohol-lower alkyl benzene sulphonate-water or urea-lower alkyl benzene sulphonate-water in order to achieve the desired viscosity, and to remain stable and easily pourable. For compositions having an organic active concentration less than about 40% by weight, the preferred alcoholic hydrotrope is ethanol which is employed at from 3% to 10% by weight of the composition, preferably at from 4% to 8%, usually in admixture with urea. For compositions having an organic active concentration greater than about 40% by weight, mixtures of ethanol with urea and/or lower alkyl benzene sulphonates are preferred. Mixtures of hydrotropes can, of course, be employed for cost effectiveness reasons irrespective of any stability/viscosity considerations.
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 (RTM), antitarnish 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 6.0-8.5,but as manufactured the compositions normally have a pH in the range 6.5-7.3 and are subjected to a final pH trimming operation to obtain the desired finished product pH. For coloured products the pH preferably lies in the range 6.5-7.2 in order to maintain colour stability.
The compositions of the invention can be made in a number of ways but it is preferred that any zwitterionic surfactant included therein is incorporated towards the end of the making process if not actually forming the last ingredient to be added. This minimises the risk of any degradation of the zwitterionic surfactant under the acid conditions existing at the beginning of the making process and also facilitates the control of the viscosity of the finished product. The glucamine surfactant should not be exposed to a pH lower than 4 or higher than 10 to prevent hydrolysis of the surfactant.
Thus, the anionic surfactant(s) can be made as aqueous solutions of alkali metal or ammonium salts with pH adjusted between 4 and 10 which are then mixed together with the N-alkanoyl -N-alkyl glucamine, followed by any ethoxylated nonionic surfactant and other suds booster(s) and the hydrotrope, after which any calcium or magnesium ion can be introduced as a water soluble salt such as the chloride or sulphate. Any zwitterionic surfactant and minor ingredients are then added at the same time as the pH and viscosity are adjusted. This method has the advantage of utilising conventional techniques and equipment but does result in the introduction of additional chloride or sulphate ions which can increase the chill point temperature (the temperature at which inorganic salts precipitate as crystals in the liquid).
In preferred compositions containing an alkyl ethoxy sulphate as the anionic surfactant, the desired alcohol and alcohol ethoxylate can be mixed together and a single sulphation and neturalisation can then be carried out on these two materials. For this, the alcohol and alcohol ethoxylate should be mixed in a weight ratio lying in the range from 4:3 to 1:6. In the most preferred technique however, a single alcohol ethoxylate stock is produced in which the levels of alcohol and ethoxylated alcohol species are controlled to provide the desired ratio of these starting materials.
Sulph(on)ation of the alcohol and alcohol ethoxylate can employ any of the conventional sulph(on)ating agents such as sulphur trioxide or chlorosulphonic acid. Neutralisation of the alkyl ether sulphuric acid and the alkyl sulphuric 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 not sufficient to permit all of the desired Ca⁺⁺ and Mg⁺⁺ ions to be added in this way, the remainder can then be added in the form of a water soluble salt.
Gel compositions of the present invention can be prepared using the general method described in US Patent No. 4615819.
Compositions in accordance with the invention are characterised by a low interfacial tension, (IFT) which is an indication of the ability to emulsify grease and oily soils, a high polypropylene cup (PPC) weight loss, which demonstrates the ability to remove greasy soils from surfaces and suspend the soils in solution, together with a superior skin mildness. This combination is not normally found in liquid detergent compositions.
Moreover, compositions in accordance with the invention display superior suds mileage performance in both hard and soft water, by comparison with prior art compositions.
The test methods used to measure these parameters are described below.

1) Interfacial Tension (IFT)

Measurement of IFT gives an indication of the ability of a surfactant sample to emulsify a soil under a defined set of conditions. IFT was determined by means of a Spinning Drop Tensiometer and a University of Texas Model 500 manufactured by the University of Texas, Austin, Texas, USA. Two instruments were employed, viz. a Model SITE 04, manufactured by Krüss GmbH Wissenscaftliche Laborgeräte, Borsteler Chaussee 85-99a, D2000 Hamburg 61 FRG under conditions representative of those encountered in Europen manual dishwashing practice. Thus, measurements were made at a sample temperature of 48°C ± 1°C using a product concentration of 0.12% by weight in water of either 2° Clark or 18° Clark hardness having a Ca : Mg ratio of 3 : 1 on a molar basis. The soil was Triolein of 99.7% purity (the remaining 0.3% comprising mixed free fatty acids) supplied by ALDRICH Chemical Company Ltd. New Road, Gillingham, Dorset, England. Results were quoted in Pa cm (1pa cm = 10 dynes/cm).

2) Polypropylene Cup weight loss (PPC)

The Polypropylene Cup Test method measures the overall grease handling capability of a product under conditions simulating those found in manual dishwashing practice. The test involves the measurement of the amount of solid fat removal from the base of a polypropylene cup at a temperature below that at which the fat melts.
A fat soil is prepared by making 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 <0°C. For use, approximately 150 ml of fat is melted in a glass beaker and held at 70-75°C. Fifteen 250 ml clean, dry, polypropylene TRIPOUR CUPS are each weighed and 6.00 ± 0.03g fat are weighed into each by pouring directly into the base of the cup without spillage on to the sides. The cups are held level and the fat allowed to solidify for 2-3 hours in a constant temperature room at 21 ± 1°C.
A 0.12% solution of the test product is prepared at 50-55°C and 100 ± 0.1g added to each of five glass jars which are then sealed with a lid. The sealed jars are placed in a water bath located in the constant temperature room and set at 45-46°C such that the solution in each jar is at a temperature of 43.8 ± 0.1°C. A similar procedure is followed for each product under test as well as for the standard product against which the test products are being compared.
The contents of a jar are then poured into a cup down the side wall, taking care not to disturb the fat in the bottom and the cup is stood level for 1/2 hour at 21°C before being transferred to an ice bath and held for 10 minutes. Upon cooling a fat deposit line develops at the surface of the solution in the cup. This pouring and cooling sequence is carried out for each cup-jar combination. After 10 minutes each cup is emptied swiftly and the cup interior dried to remove all material adhering to the cup walls between the rim and the level of the fat line. The cup is then stood upside down on absorbent kitchen roll to drain for 10-15 minutes before being dried in an oven for two hours at 30°C followed by a further hour at 50°C. The cups are then reweighed. An average weight difference between the original weight of 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 that expresses the performance ratio between the test and standard products. Products in accordance with the invention display a performance ratio of greater than about 1.3 preferably at least about 1.4.
For the purposes of the test the standard product should have a grease handling performance in the same general area as that of the experimental product at the same concentration. This can be achieved by adjusting the weight ratio of the liquid and solid fat serving as the soil composition so that the standard (reference) product provides 20-35% fat removal under the conditions of the test while the test product can have a fat removal of from 20 to 80%. The same batch of fat must be used for the test and reference products.

3) Total Suds and Suds Mileage

Total suds is the total volume of suds generated during a standard dishwashing test and is a measure of the perceived foaming ability of the formulation. Suds mileage is a measurement of the soil loading required to reduce the suds of a test solution to a defined minimum under standard conditions of product concentration, temperature and water hardness. It reflects the perceived useful life of a manual dishwashing solution. Suds mileage of the compositions under identical test conditions was made using a prepared mixed food soil and a prepared greasy soil in the mechanical sudsing test method described.

Test Conditions

Product Concentration	0.12%
Water Temperature	48°C
Water Hardness	2°Clark and 18°Clark

Mixed Food Soil

Rice/Mince/Egg "Real Meal"
1 x 392g Tin Tyne Brand Minced Beef & Onion¹
1 x 439g Tin Ambrosia Creamed Rice Pudding²
1 Egg
25 mls 2% Mixed Free Fatty Acid (MFFA) in Corn Oil*
25 mls Corn Oil
¹ Marketed by Master Foods, Kings Lynn, Norfolk, England.
² Marketed by Ambrosia Creamery, Lifton, Devon, England.
* 4g Oleic Acid, 4g Linoleic Acid, 2g Stearic Acid, 5g Palmitic Acid, 735g Pure Corn Oil.

Greasy Soil

Cake Mix Slurry
30g Sponge Mix³
60g 2% MFFA in Corn Oil*
³ Marketed by McDougalls Catering Foods Ltd., Imperial way, Warton Grange, Reading, England.

Test Method

The method uses 4 cylinders of length 30 cm and diameter 10 cm fixed side by side, and rotatable at a speed of 24 rpm about a central axis. Each cylinder is charged with 500 mls of product solution at a concentration of 0.12% and a temperature of 48°C. The outer two cylinders are used for one of the products being compared and the inner two for the other product.
The cylinders are rotated for 2 minutes, stopped, the initial suds are measured and a soil load is then added typically in 2ml aliquots. After 1 minute the cylinders are restarted and allowed to rotate for 1 minute. The suds height is noted and 2 mls of the soil is added to each cylinder. After 1 minute the cylinders are restarted. This process continues until the suds height in the cylinder is lower than 0.6 cms.
The total of all of the suds height measurements in each test (i.e. until the suds height becomes lower than 0.6 cms) forms the Total Suds measurement.
One product is designated as the control and suds index and suds mileage figures are calculated for the other product versus the 'control' product on the following basis.
The invention is illustrated in the following non-limitative examples in which all parts and percentages are by weight unless otherwise specified.

Example 1

A range of core surfactant systems was prepared containing a mixture of alkyl ethoxysulphate surfactant and N-lauroyl-N-methyl glucamine. The alkyl ethoxysulphate was derived from a C₁₂-C₁₄ primary alcohol condensed with an average of 0.8 moles of ethylene oxide per mole of alcohol and neutralised with a mixture of ammonium and magnesium ions so as to contain 0.22 moles of magnesium per mole of alkyl ethoxysulphate. A simulated product of 30% core surfactant concentration was first made in distilled water. A 0.12% by weight solution of this product was then formed in either soft (2° Clark) or hard (18° Clark) water and tested for IFT, and in 2° Clark water for PPC greasy soil removal, using the test methods hereinbefore described. This procedure was followed for ratios of alkyl ethoxy sulphate to alkyl glucamine of 100:0, 75:25, 65:35, 50:50, 25:75 and 0:100 and the results are shown below.

IFT (Pa.cm) AES : GA weight ratio

Water Hardness 100:0 75:25 65:35 50:50 25:75 0:100

2° 0.35 0.12 0.12 0.14 0.16 0.10

18° 0.21 0.09 0.07 0.12 0.06 0.07

PPC

2° 1.0 - 1.6 1.5 - 1.3
It can be seen that the addition of the alkyl glucamine to the anionic surf act ant produces a marked improvement in grease emulsification, as shown by the IFT values, and in greasy soil handling, as shown by the enhanced PPC soil removal values.

The above co-surfactant mixtures were also evaluated for Total Suds Height and suds mileage performance using the previously described test methods. However the results were not indexed against a standard product but were reported directly as Total suds/Suds mileage figures.

	AES: GA Weight Ratio
	100:0	95:5	90:10	75:25	65:35	50:50	0:100
Hardness 2°Clark Real Meal Soil	260/5.0	344/6.5	416/7.5	567/10.0	657/10.0	604/10.5	458/10.0
Greasy Soil	250/4.5	277/4.8	333/5.5	407/8.0	528/8.5	355/6.5	100/2.0
18°Clark Real Meal Soil	300/5.5	415/6.8	498/8.0	595/9.5	600/9.7	621/10.0	400/10.0
Greasy Soil	302/4.8	316/5.0	369/6.0	380/6.0	348/5.5	283/4.7	64/1.0

From a consideration of both the greasy soil removal data and the sudsing data under greasy soil loading conditions, it can be seen that a preferred range of mixtures for both grease removal and sudsing performance lies between 75 : 25 Alkyl ethoxysulphate : Alkyl glucamine and 50 : 50 Alkyl ethoxysulphate : Alkyl glucamine, with an optimum at about 65 : 35. A 100% Alkyl glucamine system gives comparable grease removal performance but is seriously deficient in total sudsing and suds mileage particularly under greasy soil conditions.

EXAMPLE 2

The following compositions A - E were prepared:

Composition A represents a comparative commercially available liquid detergent dishwashing product while Compositions B, C, D & E are in accordance with the invention.

C_11.8 linear alkyl benzene sulphonate	6.5	-	-	-	-
N-Coconut alkanoyl-N-methyl glucamine	-	12.5	10.0	8.0	12.8
C₁₂₋₁₃ alkyl (EO)_0.8 sulphate	20.5	11.0	15.0	16.0	10.0
C₁₂₋₁₃ alkyl (EO)₃ sulphate	-	-	-	-	2.7
Primary alcohol ethoxylate¹	4.0	6.0	4.0	8.0	7.0
Mg⁺⁺ ion	0.35	0.20	0.25	0.5	-
C₁₂-C₁₄ alkyl di methyl betaine.	1.5	4.0	3.0	2.0	2.0
Coconut Monoethanolamide	3.8	-	-	-	-
C₁₂-C₁₄ alkyl dimethyl amine oxide	-	-	4.0	-	-
Sodium Cumene sulphonate	1.0	1.0	2.0	2.0	2.0
Ethanol	4.5	5.0	5.0	5.0	5.0
Urea	0.5	-	-	-	-
Water	----------to 100 ---------

¹ A predominantly linear C₉-C₁₁ blend containing an average of 10 ethylene oxide units per mole of alcohol, and containing less than 2% by weight of unethoxylated alcohol.

IFT, PPC and suds mileage values were obtained for all five products and the results are expressed below.

1. IFT (Pa.cm) A B C D E

2°Clark 0.15 0.08 0.08 0.09 0.08

18°Clark 0.11 0.06 0.06 0.07 0.06

2. PPC

2°Clark 1 1.6 1.7 1.7 N/A

3. Total Suds/Suds Mileage

Mixed soil A B C D E

2°Clark 100/100 189/167 186/170 135/128 142/129

18°Clark 100/100 145/140 177/153 121/119 138/150

Greasy Soil

2°Clark 100/100 132/129 130/132 123/122 150/150

18°Clark 100/100 95/113 98/115 108/107 102/99

Claims

An unbuilt liquid or gel-form detergent composition in the form of a physically stable aqueous solution comprising from 20% to 50% by weight of the composition of a core surfactant mixture, comprising by weight of the mixture,
a) from 5% to 95% of at least one water-soluble anionic sulphate or sulphonate surfactant salt;

b) from 95% to 5% by weight of the mixture of one or more compounds having the general formula
wherein Z is a polyhydroxy hydrocarbyl moiety having a linear hydrocarbon chain with at least three hydroxy groups connected directly to the chain, said moiety being derived from glucose and mixtures thereof with maltose, the maltose comprising not more than 33% by weight of the mixture, R is a saturated or unsaturated alkyl group of from 8 to 16 carbon atoms or a mixture of such groups and R₁ is a C₁-C₄ alkyl or C₂-C₄ hydroxyalkyl group;
whereby a 0.12% by weight aqueous solution of the surfactant mixture of said composition, in water of 2° Clark mineral hardness (Ca:Mg ratio of 3 : 1) and temperature of 48°C, has
i) a spinning drop interfacial tension (IFT) of less than 0.2 Pa cm using a triolein soil of 99.7% purity;

ii) a greasy soil removal value in the Polypropylene Cup (PPC) Test of greater than 1.3 x the value obtained in the same test under the same conditions using a 0.12% solution of the anionic surfactant component(s) alone.
An unbuilt liquid or gel-form detergent composition according to claim 1 wherein the polyhydroxy hydrocarbyl moiety of component b) is derived from glucose and mixtures thereof with maltose in which maltose comprises no more than 25% by weight of the mixture.
An unbuilt liquid or gel-form detergent composition according to either one of claims 1 & 2 comprising from 22% to 40% of the mixture of core surfactants.
An unbuilt liquid or gel-form detergent composition according to any one of claims 1-3 wherein the mixture of core surfactants comprises from 20% to 80% of (a) and from 80% to 20% of (b), more preferably from 40% to 70% of (a) and from 60% to 30% of (b).
An unbuilt liquid or gel-form detergent composition according to any one of Claims 1-4 wherein component a) is selected from C₁₀-C₁₆ alkyl ethoxy sulphates containing an average of up to 6 moles of ethylene oxide per mole of alkyl ethoxy sulphate, C₁₀-C₁₈ alkyl glyceryl ether sulphonates, C₁₀-C₁₆ paraffin sulphonates, C₉-C₁₇ acyl-N-C₁-C₄ alkylglucamine sulphates and mixtures thereof.
An unbuilt liquid or gel-form detergent composition according to any one of Claims 1-5 wherein component a) comprises a primary C₁₂-C₁₄ alkyl ethoxy sulphate surfactant containing an average of no more than 1.5 ethoxy groups per mole of alkyl ethoxysulphate, preferably an average in the range of from 0.4 to 1.0 groups per mole of alkyl ethoxysulphate.
An unbuilt liquid or gel-form detergent composition according to any one of Claims 1-6 incorporating Mg⁺⁺ in an amount of up to 1.5%, preferably from 0.5% to 1.0% by weight of the composition
An unbuilt liquid or gel form a composition according to claim 7 incorporating Ca⁺⁺ in an amount of up to 1% by weight of the composition preferably from 0.3% to 0.5% by weight.
An unbuilt liquid or gel-form detergent composition according to any one of Claims 1-8 incorporating one or more suds promoting materials, the or each being present in an amount of from 1% to 8% by weight of the composition.
An unbuilt liquid or gel-form detergent composition according to Claim 9 wherein the suds promoting material is selected from C₁₀-C₁₆ alkyl mono- or di- C₂-C₃ alkanolamides, C₁₂-C₁₆ alkyl or alkyl amido betaines, C₁₂-C₁₆ alkyl sulphobetaines, C₁₀-C₁₆ alkyl, di C₁₋₄ alkyl or di C₂₋₄ hydroxyalkyl amine oxides, C₉-C₁₂ primary alcohol ethoxylates containing an average of from 7 to 12 ethylene oxide groups per mole of alcohol and mixtures thereof.
An unbuilt liquid detergent composition according to either one of Claims 9 and 10 comprising a combination of a C₁₂-C₁₄ alkyl dimethyl betaine, and a C₉₋₁₁ primary alcohol condensed with an average of from 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.
An unbuilt liquid detergent composition according to any one of the preceding claims further including a hydrotrope selected from urea, a C₁-C₃ aliphatic alcohol, a lower alkyl or dialkyl benzene sulphonate or a mixture of any thereof.
An unbuilt liquid dishwashing detergent composition according to any one of the preceding claims having a chill point of not an than 8°C, preferably less than 5°C.
A physically stable unbuilt liquid dishwashing detergent composition according to any one of the preceding claims wherein the composition includes an opacifier.
An unbuilt liquid or gel-form detergent composition according to any one of the preceding claims having a pH in the range from 6.0 to 8.5.