DE69125022T2 - ALKYLETHOXYCARBOXYLATTENSID AND CALCIUM OR MAGNESIUM ION CONTAINING Mild DISHWASHER DETERGENT COMPOSITION - Google Patents

Description

TECHNICAL AREA

The present invention relates to mild liquid or gel dishwashing detergent compositions containing alkyl ethoxycarboxylates as surfactants (alternatively referred to as alkyl polyethoxycarboxymethylates, alkyl polyethoxyacetates, alkyl polyethercarboxylates, etc.) of the type described in U.S. Patent Nos. 2,183,853; 2,653,972; 3,003,954; 3,038,862; 3,741,911 and 3,941,710; British Patent Nos. 456,517 and 1,169,496; Canadian Patent No. 912,395; French Patent Nos. 2,014,084 and 2,042,793; in Dutch Patent Applications Nos. 7 201 735-Q and 7 406 336; and in Japanese Patent Applications Nos. 96 579/71 and 99 331/71.

STATE OF THE ART

There is a significant need for mild liquid or gel dishwashing detergents capable of providing good grease removal. These compositions are well known in the art and are described, for example, in U.S. Patent Nos. 4,316,824 (Panchen), 4,681,704 (Bernardino et al.), 4,133,779 (Hellyer et al.) and 4,615,819 (Leng et al.). Although these compositions are good cleaners with respect to grease and dirt, they can be harsh on the skin under certain conditions, particularly when used during the dry winter months.

The art also contains numerous detergent compositions which are mild to the skin, see for example EP-0-384 982. These mild compositions often contain sulfates of highly ethoxylated alcohols. Furthermore, betaines have been proposed to improve the mildness of liquid dishwashing detergent compositions. See for example US Pat. No. 4,555,360 (Bissett et al.). Alkyl ethoxycarboxylates are also known to be used as mild surfactants in liquid detergent compositions. See Japanese Patent Applications 48-60706 and 48-64102. However, these alkyl ethoxycarboxylate surfactants are considered to have low grease removal ability. described and the use of other surfactants is necessary to achieve the desired cleaning.

Rarely are these two important features of mildness and grease removal ability present together in one product, see for example EP-A-399 752 which was not published on the priority date of the present invention and represents prior art under Art.54(3) EPC. It is generally believed that one feature must be sacrificed for the benefit of the other. It has been found that detergent compositions containing a particular surfactant mixture of alkyl ethoxycarboxylates can provide a detergent composition which exhibits good grease removal while at the same time being mild to the skin. This dual benefit is enhanced when the composition has a pH of 7 to 11 and contains a small amount of divalent ions, e.g. magnesium or calcium ions.

However, these alkaline compositions containing magnesium ions can exhibit poor stability during storage. In an alkaline environment, precipitation of magnesium hydroxide can be a significant problem. It is therefore an object of this invention to provide a detergent composition which exhibits good grease removal and mildness to the skin while at the same time exhibiting improved stability during storage of the composition.

SUMMARY OF THE INVENTION

The present invention relates to a mild, liquid or gel-like, preferably liquid, dishwashing detergent composition which:

(a) 5% to 70% of a surfactant mixture, comprising:

(i) 80% to 100% of alkyl ethoxycarboxylates of the formula

RO(CH₂CH₂O)xCH₂COO⊃min;M⁺,

wherein R represents a C₁₂-C₁₆ alkyl group, x ranges from 0 to 10 and the ethoxylate distribution is such that, by weight, the amount of material in which x is 0 is less than 20% and the amount of material in which x

is greater than 7, represents less than 25%, wherein the average value of x is from 2 to 4 when R averages C₁₃ or shorter and the average value of x is from 3 to 6 when R averages longer than C₁₃, and M represents a cation;

(ii) 0% to 10% of alcohol ethoxylates of the formula

RO (CH₂CH₂O) xH,

wherein R represents a C₁₂-C₁₆ alkyl group and x ranges from 0 to 10 and the average value of x is less than 6; and

(iii) 0% to 10% of soaps of the formula

RCOÖ⊃min;M⁺,

wherein R represents a C₁₁-C₁₅ alkyl group and M represents a cation;

(b) about 0.1% to 4% of calcium or magnesium ions; and

(c) a calcium or magnesium chelating agent which forms a soluble calcium or magnesium complex having a logarithm of formation constant, log Kf, of from 0.5 to 5 in an amount sufficient to prevent the formation of calcium carbonate or magnesium hydroxide precipitates in the composition; excluding glycine and citrate;

wherein a 10 wt.% aqueous solution of said composition has a pH of 7 to 11.

DETAILED DESCRIPTION OF THE INVENTION

The mild liquid or gel, preferably liquid, dishwashing detergent compositions of the present invention contain a surfactant mixture comprising a major proportion of alkyl ethoxycarboxylate surfactant and no or little alcohol ethoxylate and no or little soap as contaminating byproducts, and a calcium or magnesium ion source. In the magnesium ion-containing compositions of the present invention, a chelating agent for the magnesium and a buffer for alkalinity are also required. In the calcium ion-containing compositions of the present invention, a chelating agent for the calcium may also be required. These and other supplementary optional ingredients typically found in liquid or gel dishwashing detergent compositions are listed below.

Alkyl ethoxycarboxylate-containing surfactant mixture

The liquid compositions of this invention contain from about 5% to 50%, preferably from about 10% to 40%, most preferably from about 12% to 30%, by weight of a surfactant mixture which is limited in the amounts of contaminant materials. The gel compositions of this invention contain from about 5% to about 70%, preferably from about 10% to about 45%, most preferably from about 12% to about 35% of the surfactant mixture.

The surfactant mixture contains about 80% to 100%, preferably about 85% to 95%, most preferably 90% to 95%, of alkyl ethoxycarboxylates of the general formula RO(CH2CH20)xCH2COO-M+, where R is a C12-C16 alkyl group, x is from 0 to 10, and the ethoxylate distribution is such that, by weight, the amount of material where x is 0 is less than 20%, preferably less than about 15%, most preferably less than about 10%, and the amount of material where x is greater than 7 is less than 25%, preferably less than about 15%, most preferably less than about 10%, with the average value for x being from 2 to 4. is when R is on average C₁₃ or shorter, and the average value of x is from 3 to 6 when R is on average longer than C₁₃, and M is a cation preferably selected from alkali metal, alkaline earth metal, ammonium, mono-, di- and triethanolammonium, most preferably sodium, potassium, and mixtures thereof with magnesium ions. The preferred alkyl ethoxycarboxylates are those wherein R is a C₁₂- C₁₄ alkyl group.

Suitable alcohol precursors of the alkyl ethoxycarboxylates of this invention are primary aliphatic alcohols containing from about 12 to about 16 carbon atoms. Other suitable primary aliphatic alcohols are the linear primary alcohols obtained by the hydrogenation of vegetable or animal fatty acids, such as coconut, palm kernel and tallow fatty acids, or by ethylene build-up reactions followed by hydrolysis, such as in the Ziegler-type processes. Preferred alcohols are n-alkyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl and n-hexadecyl. Other suitable alcohol precursors include primary alcohols which contain a proportion of branching at the beta or 2 carbon atoms, wherein the alkyl branching contains from 1 to 4 carbon atoms. In such alcohols, at least 30% of any alcohol of a particular chain length is desirably linear and the branching preferably comprises about 50% methyl groups with minor amounts of ethyl, propyl and butyl groups. These alcohols are conveniently prepared by reacting linear olefins having from about 11 to 17 carbon atoms with: carbon monoxide and hydrogen. These processes produce both linear and branched chain alcohols, and the mixtures can either be used as such or they can be separated into the individual components and then recombined to obtain the desired mixture.

Typical processes for the preparation of "oxo" halides, which are subsequently used to produce alcohols, are described in U.S. Patent Nos. 2,564,456 and 2,587,858, and the direct hydroformylation of olefins to produce alcohols is given in U.S. Patent Nos. 2,504,682 and 1,581,988.

Equivalent secondary alcohols may also be used. It will be appreciated that using a single chain length olefin as the starting material will give the corresponding single chain length alcohol, but it is generally more economical to use olefin mixtures having a carbon chain length distribution around the desired mean. This will of course give an alcohol mixture having the same chain length distribution around the mean.

Primary aliphatic alcohols obtained from vegetable oils and fats and from other petroleum starting materials which have alkyl or alkylene groups as part of their structure will also have a chain length range. Since the chain length range is C8-C20 and above, it is therefore common practice to separate the product from such starting materials into different chain length ranges, which are selected with regard to their final use.

The desired average ethoxy chain length of the alcohol ethoxylate can be obtained using a catalytic ethoxylation process in which the molar amount of ethylene oxide reacted with each equivalent of fatty alcohol will correspond to the average number of ethoxy groups in the ethoxylated alcohol. It is known that the addition of ethylene oxide to alkanols is promoted by a catalyst, most conveniently a catalyst of either strongly acidic or strongly basic character. Suitable basic catalysts are the basic salts of the alkali metals of Group I of the Periodic Table, e.g. sodium, potassium, rubidium and cesium, and the basic salts of certain alkaline earth metals of Group II of the Periodic Table, e.g. calcium, strontium, barium and in some cases magnesium. Suitable acid catalysts broadly include the Lewis acid of Friedel-Crafts catalysts. Specific examples of these catalysts are the fluorides, chlorides and bromides of boron, antimony, tungsten, iron, nickel, zinc, tin, aluminum, titanium and molybdenum. The use of complexes of such halides with, for example, alcohols, ethers, carboxylic acids and amines has also been described. Still other examples of known acid alkoxylation catalysts are sulfuric and phosphoric acids; perchloric acid and the perchlorates of magnesium, calcium, manganese, nickel and zinc; metal oxalates, sulfates, phosphates, carboxylates and acetates; alkali metal fluoroborates, zinc titanate and the metal salts of benzenesulfonic acid. The type of catalyst used will determine the distribution of the ethoxy group range. Stronger catalysts will result in a very narrow distribution of ethoxy groups around the mean. Weaker catalysts will result in a broader distribution.

The surfactant mixture also contains from 0% to 10%, preferably less than about 8%, most preferably less than 5%, of alcohol ethoxylates of the formula RO(CH₂CH₂O)xH, wherein R is a C₁₂-C₁₆ alkyl group and x ranges from 0 to 10 and the average value of x is less than 6. The surfactant also contains from 0% to 10%, preferably less than about 8%, most preferably less than 5% of soaps of the formula RCOO⁻M⁺, wherein R is a C₁₁-C₁₅ alkyl group and M is a cation as described above.

The non-carboxylated alcohol ethoxylates identified above are detrimental to the alkyl ethoxycarboxylate surfactant mixture, particularly in view of the performance benefits that can be achieved thereby. It is therefore critical that the alkyl ethoxycarboxylate-containing surfactant mixture used in this invention contains less than about 10% by weight of the alcohol ethoxylates from which the alkyl ethoxycarboxylates are obtained. Although commercially available alkyl ethoxycarboxylates contain 10% or more of alcohol ethoxylates, there are known ways to obtain the alkyl ethoxycarboxylates of the desired high purity. For example, unreacted alcohol ethoxylates can be removed by steam distillation, U.S. Patent No. 4,098,818 (Example I), or by recrystallization of the alkyl ethoxycarboxylate, British Patent No. 1,027,481 (Example 1). Other routes to the desired carboxylates consist of reacting sodium hydroxide or sodium metal and monochloroacetic acid or its salts with alcohol ethoxylates under specific combinations of pressure and temperature as described in U.S. Patent Nos. 3,992,443 and 4,098,818 and in Japanese Patent Application No. 50-24215.

Alternatively, a hindered base such as potassium tert-butoxide can be substituted for the sodium hydroxide in the above-cited patents to give alkyl ethoxycarboxylates of high purity with less stringent temperature and pressure requirements. In particular, a hindered base of the formula RO⊃min;M⊃plus, which generally consists of an alkyl group, a reactive oxygen center and a cation, can be used. The structure of this hindered base is secondary or tertiary and it comprises a non-linear alkyl group with at least one branching point within 3 carbon atoms of the reactive center, the oxygen atom, and an alkali metal or alkaline earth metal cation. The process comprises reacting the alcohol ethoxylates with the above-cited and either anhydrous chloroacetic acid, in a molar ratio of the hindered base to the anhydrous chloroacetic acid of 2:1, or with an alkali metal salt or alkaline earth metal salt of anhydrous chloroacetic acid, in a molar ratio of the hindered base to the alkali metal salt or alkaline earth metal salt of chloroacetic acid of 1:1, wherein the molar ratio of ethoxylated fatty alcohol to the anhydrous chloroacetic acid or the alkali metal salt or alkaline earth metal salt thereof is from about 1:0.7 to about 1:1.25, the temperature is from about 20°C to 140°C, and the pressure is from about 0.133 kPa to 101 kPa (about 1 to 760 mm Hg).

Other routes to high purity alkyl ethoxycarboxylates include reacting alcohol ethoxylate with oxygen in the presence of platinum, palladium or other precious metals as described in U.S. Patent Nos. 4,223,460 (Examples 1-7); 4,214,101 (Example 1); 4,348,509; German Patent No. 3,446,561; and Japanese Patent Application No. 62,198,641. One of the byproducts of such reactions is soap, which, as described above, should be present in limited amounts to avoid adversely affecting the cleaning and mildness benefits provided by the present compositions. This can be done by using an alcohol ethoxylate starting material containing small amounts of non-ethoxylated fatty alcohol and selecting catalysts which preferentially oxidize the terminal methylene in the alcohol ethoxylate at least about 90% of the time, preferably at least about 95% of the time. Oxidation of non-terminal methylene groups in the alcohol ethoxylate will form soap from the ethoxylated fatty alcohol components.

The cations of the alkyl ethoxycarboxylates used according to the invention can be alkali metal, alkaline earth metal, ammonium and lower alkanolammonium ions. The cation source for alkyl ethoxycarboxylates comes from the neutralization of the alkyl ethoxycarboxylic acid and from additional components, e.g. the performance-enhancing salts containing divalent ions.

Preferred cations for the compositions of the invention are ammonium, sodium and potassium. For compositions having a pH of 7 to 8, ammonium is most preferred, but at pH values above 8 it is undesirable due to the release of small amounts of ammonia gas resulting from the deprotonation of the ammonium ions of the composition.

For liquid compositions of the invention, potassium is preferred over sodium because it makes the compositions of the invention more resistant to precipitation at low temperatures and provides improved solubility for the composition. On the other hand, for gel-like compositions of the invention, sodium is preferred over potassium because it facilitates gel formation of a composition. Mixtures of the cations can be present in any composition of the invention.

pH value of the composition

Traditionally, liquid dishwashing detergent compositions have a pH of 7. For detergent compositions containing alkyl ethoxycarboxylate surfactant, it is known that a more alkaline pH greatly improves grease cleaning compared to a neutral pH, especially under soft water conditions. This cleaning advantage appears to be unique to compositions containing the present alkyl ethoxycarboxylates surfactant. Surprisingly, the compositions of the invention are also gentler on the hands at this alkaline pH than at a pH of 7. The compositions of the invention have a pH of from 7 to 11, preferably from 8 to 10, most preferably from 8 to 9.5, the pH of a 10% by weight aqueous solution being determined with a pH meter.

In a composition containing calcium ions, no or only a small formation of calcium hydroxide precipitates occurs over the entire pH range of the compositions according to the invention, i.e. from about 7 to 11. Calcium hydroxide is much more soluble in water than magnesium hydroxide.

At pH values of about 7 to 9 there is little or no possibility of the formation of calcium carbonate precipitates, because at these pH values there is little or no source of carbonate ions available to interact with the free calcium ions to form CaCO3 precipitates, since the carbonate species are in the form of bicarbonate or carbonic acid, which do not form insoluble calcium complexes.

At pH values of about 9 to 11, the bicarbonate and carbonic acid species are deprotonated to form carbonate, which readily interacts with calcium to form calcium carbonate precipitates. At these high pH values, a calcium chelator is therefore required to prevent the formation of these undesirable species.

If a composition having a pH greater than about 7 is to provide performance improvement, it should contain a buffer capable of maintaining the alkaline pH in the composition and in dilute solutions, i.e., in aqueous solutions containing about 0.1% to 0.2% by weight of the composition. The pKa of this buffer should be about 0.5 to 1.0 pH units below the desired pH of the composition (which is determined as described above).

Dishwashing detergent compositions of the invention will, in use, i.e., diluted and applied to soiled dishes, be subjected to the acidic effects caused by food soils. To maintain the performance benefits of the compositions in use, they should contain a buffer having a pKa of about 0.5 to 1.0 pH units below the desired pH. Under these conditions, the buffer will most effectively regulate pH while using the least amount of it.

The buffer may itself be an effective detergent or it may be a low molecular weight organic or inorganic material used in these compositions solely to maintain an alkaline pH. Suitable buffers for compositions according to the invention are nitrogen-containing materials. Some examples are amino acids, with the exception of glycine, or lower alcohol amines such as mono-, di- and triethanolamine. The Preferred nitrogen-containing buffers are 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methylpropanol, 2-amino-2-methyl-1,3propanol and tris-(methanol)aminomethane (aka Tris); n-methyldiethanolamine, 1,3-diamino-2-propanol, N,N-tetramethyl-1,3diamino-2-propanol, bis(2-ethanol)glycine (aka bicine); imidazole, N-tris-(methanol)methylglycine (aka tricine) are also preferred.

These buffers are typically present in an amount of from about 0.1% to 15% by weight, preferably from about 1% to 10% by weight, most preferably from about 1.5% to 8% by weight.

Calcium or magnesium ions

It has been found that in compositions containing the present alkyl ethoxycarboxylates, the presence of divalent cations particularly improves the cleaning of greasy soils. This is particularly true when the compositions are used in softened water which contains few divalent ions. Liquid dishwashing detergent compositions containing alkyl ethoxycarboxylates which do not meet the narrow definition of this invention will benefit less from the addition of divalent ions and in many cases will actually show reduced cleaning performance after the addition of divalent cations. It is believed that the divalent ions improve the arrangement of the present alkyl ethoxycarboxylates at the oil/water interface, thereby reducing interfacial tension and improving grease cleaning.

Furthermore, it has been found that the formulation of such divalent ion-containing compositions in matrices having an alkaline pH is difficult due to the incompatibility of the divalent ions with hydroxide ions. When both divalent ions and alkaline pHs are combined in the surfactant mixture of this invention, grease cleaning is achieved which is superior to that achieved either at an alkaline pH or by divalent ions alone. However, during storage the stability of these compositions is reduced due to the formation of hydroxide precipitates. This is particularly noticeable with magnesium-containing compositions.

It has now been found that compositions of the invention containing calcium or magnesium ions have good grease removal, are mild to the skin and exhibit good stability on storage. The calcium ions are present in the compositions of the invention in an amount of from about 0.1% to 4% by weight, preferably from about 0.5% to 3.5% by weight. The incorporation of a magnesium chelating agent (described below) in the compositions of the invention prevents the formation of magnesium hydroxide precipitates and enables larger amounts of magnesium ions to be incorporated at higher pH values, which are required in soft water areas where the concentration of divalent ions is low. The amount of magnesium ions in the composition is therefore about 0.1 wt% to 3 wt%, preferably about 0.3 wt% to 2 wt%, most preferably about 0.5 wt% to 1 wt%.

Preferably, the calcium or magnesium ions are added as a chloride, acetate or nitrate salt to the compositions containing an alkali metal or ammonium salt of the alkyl ethoxycarboxylate, most preferably the sodium salt, after the composition has been neutralized with a strong base.

At pH values of 7 to 9, compositions containing calcium or magnesium ions show benefits in terms of improved grease cleaning. Without being supported by theory, it is believed that calcium or magnesium binds the alkyl ethoxycarboxylate molecules more tightly, allowing for closer arrangement at the water/oil interface. Lower values of interfacial tension are measured for compositions containing calcium ions compared to compositions containing other divalent ions. In addition, at these pH values, the compositions of the invention show better stability during storage compared to other compositions as described above.

At pH values of 9 to 11, the amount of chelating agent required for calcium-containing compositions is less than that required for magnesium-containing compositions is required, although both calcium-containing and magnesium-containing compositions require chelating agents to prevent precipitate formation.

The formulation of compositions containing calcium ions is easier than that of compositions containing magnesium ions because the pH of such compositions can be easily adjusted without causing precipitate formation, whereas in the formulation of magnesium compositions, hydroxide precipitates once formed cannot be easily dissolved again.

In alkaline compositions according to the invention, a higher amount of calcium ions can be tolerated at higher pH values without the formation of undesirable precipitates, provided that a certain amount of a chelating agent is used.

The amount of calcium or magnesium ions present in compositions of the invention will depend on the amount of total anionic surfactant present therein, including the amount of alkyl ethoxycarboxylates. The molar ratio of divalent ions to total anionic surfactant is from about 0.25:1 to about 2:1 for compositions of the invention containing calcium and from about 0.25:1 to about 1:1 for compositions of the invention containing magnesium.

Chelating agents for calcium or magnesium

The composition according to the invention may contain a calcium or magnesium chelating agent to complex calcium or magnesium ions present in the liquid phase of the composition, thereby preventing the interaction between the calcium or magnesium ions and the hydroxide ions which would lead to the formation of CaCO₃ or Mg(OH)₂ precipitates, particularly at pH values of 9 to 11.

The complex formed between the calcium or magnesium and the chelating agent must be soluble. If an insoluble complex of calcium or magnesium and the chelating agent is formed, it will cause an unsightly cloudiness of the product and if the complex settles to the bottom of the product, insufficient amounts of calcium or magnesium ions may released during normal addition of the product into the washing solution.

The chelating agent must be only moderately associated with the calcium or magnesium ions, i.e., only strongly enough to prevent interaction between the calcium and carbonate ions or the magnesium and hydroxide ions, but not so strongly as to significantly reduce the amount of calcium or magnesium ions available in dilute solution. The logarithm of the formation constant, log Kf, for the chelating agent is therefore 0.5 to 5.

The amount of chelating agent present in the compositions of the invention is an amount sufficient to prevent the formation of CaCO3 or Mg(OH)2 precipitates in the composition. This amount depends on three factors: the desired pH of the composition, the amount of calcium or magnesium ions in the composition, and the strength of the chelating agent, i.e. its log Kf value.

At pH values of 7 to 9 it is unlikely that a formation of calcium precipitates will occur (see above). It is therefore unlikely that a chelating agent will be required in compositions having such pH values. At pH values of 9 to 11 the tendency for calcium carbonate precipitates increases (see above) and therefore some amount of a calcium chelating agent may be required.

With respect to compositions containing magnesium ions, desirable higher pH values of a composition in dilute solution result in higher concentrations of hydroxide ions in the composition. This in turn results in more hydroxide ions in the composition being available to interact with the magnesium ions in the composition and there being a greater tendency therein to form Mg(OH)2 precipitates. This results in a higher amount of chelating agent having to be incorporated into the composition, assuming that the same chelating agent is employed. The use of a stronger chelating agent, ie one with a higher log Kf value, could be used instead of using a larger amount of a weaker chelating agent. It is important that the logarithm of the formation constant, log Kf, must be used in determining the amount of chelating agent used in a composition. The log Kf of the chelating agent is from 0.5 to 5, preferably from 1 to 3.5. The higher the log Kf, the tighter the binding to the calcium ions and the less amount is required to prevent the formation of CaCO3 precipitates in the composition. The amount of chelating agent in the compositions of the invention is given below in Table I. To determine the amount of chelating agent to be used in the compositions of the invention, the formulator must determine the log Kf of the chelating agent. A method for determining the formation constant of these chelating agents is described in Determination and Use of Stability Constants; AE Martell and KJ Motekaitis; VC Publishers Inc. (1988, NY, NY). Formation constants for various common inorganic compounds are given in Critical Stability Constants; RM Smith and AE Martell; Plenum Publishers (1974-81, NY, NY), which literature is incorporated herein by reference. Based on the amount of calcium ions and the pH desired for the composition, the formulator can determine a range for the amount of chelating agent required in the composition. Table I

Examples of suitable chelating agents are bicine (bis(2-ethanol)glycine), N-(2-hydroxyethyl) iminodiacetic acid (HIDA), N-(2,3-dihydroxypropyl) iminodiacetic acid (GIDA) and their alkali metal salts, but excluding glycine and citrate. Mixtures of the above are acceptable.

The preferred chelating agent is Bicine.

Primary amines are not preferred as chelating agents for magnesium-containing compositions according to the invention, since they tend to cause discoloration of the composition during storage. Preferred compositions according to the invention are therefore essentially free of chelating agents which are primary amines.

Some alkalinity chelators and buffers work well together in magnesium-containing compositions of the present invention. These include: alkanolamines (including 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanedial, and 2-amino-2-methylpropanol); bicine and Tris; bicine and N-methyldiethanolamine; bicine and diethanolamine; bicine and 1,3-diamino-2-propanol; and bicine and triethanolamine. Those combinations containing bicine are most preferred.

Co-surfactants

The compositions of this invention preferably contain certain co-surfactants to aid lathering, detergency and/or mildness.

Included in this category are various anionic surfactants commonly used in liquid or gel dishwashing detergents. The anionic cations associated with these anionic surfactants may correspond to the cations described above for the alkyl ethoxycarboxylates. Examples of anionic co-surfactants useful in the present invention include the following classes:

(1) Alkylbenzenesulfonates, wherein the alkyl group contains 9 to 15 carbon atoms, preferably 11 to 14 carbon atoms in a straight chain or branched chain configuration. A particularly preferred linear alkylbenzenesulfonate contains about 12 carbon atoms. These surfactants are described in detail in U.S. Patent Nos. 2,220,099 and 2,477,383.

(2) Alkyl sulfates obtained by sulfating an alcohol having 8 to 22 carbon atoms, preferably 12 to 16 carbon atoms. The alkyl sulfates have the formula ROSO⁻M⁺, where R represents the C₈₋₂₂ alkyl group and M is a mono- and/or divalent cation.

(3) Paraffin sulfonates containing 8 to 22 carbon atoms, preferably 12 to 16 carbon atoms in the alkyl radical.

These surfactants are commercially available as Hostapur SAS from Hoechst Celanese.

(4) Olefin sulfonates having 8 to 22 carbon atoms, preferably 12 to 16 carbon atoms. U.S. Patent No. 3,332,880 contains a description of suitable olefin sulfonates.

(5) Alkyl ether sulfates which are obtained by ethoxylating an alcohol having 8 to 22 carbon atoms, preferably 12 to 16 carbon atoms, with less than 30, preferably less than 12 moles of ethylene oxide. The alkyl ether sulfates have the formula:

RO (C₂H₄O) xSO₃⊃min;M⁺,

wherein R represents the C8-22 alkyl group, x is from 1 to 30 and M represents a mono- or divalent cation.

(6) Alkyl glyceryl ether sulfonates having 8 to 22 carbon atoms, preferably 12 to 16 carbon atoms in the alkyl radical.

(7) Fatty acid ester sulfonates of the formula:

R₁-CH(SO₃⊃min;M⁺)CO₂R₂,

wherein R₁ is a linear or branched alkyl of about C₈-C₁₈, preferably C₁₂-C₁₆, and R₂ is a linear or branched alkyl of about C₁-C₆, preferably predominantly C₁, and M⁺ is a mono- or divalent cation.

(8) Mixtures thereof.

The anionic surfactants described above are all commercially available. It should be noted that although both dialkyl sulfosuccinates and fatty acid ester sulfonates work well at neutral to slightly alkaline pH, they will not be chemically stable in a composition with a pH much higher than about 8.5.

Other useful cosurfactants for use in the compositions are the nonionic fatty alkyl polyglucosides. These surfactants contain straight or branched chain C8 -C15 alkyl groups, preferably about C12 -C14 alkyl groups, and an average of about 1 to 5 glucose units, with an average of 1 to 2 glucose units being most preferred. U.S. Patent Nos. 4,393,203 and 4,732,704 describe these surfactants.

The compositions of the invention may also comprise a polyhydroxy fatty acid amide surfactant having the structural formula: wherein: R¹ is H, C₁-C₄ hydrocarbyl, 2-hydroxyethyl, 2-hydroxypropyl or a mixture thereof, preferably C₁-C₄ alkyl, more preferably C₁ or C₂ alkyl, most preferably C₁ alkyl (ie methyl); and--R² is C₅-C₃₁ hydrocarbyl, preferably linear C₇-C₁₇ alkyl or alkenyl, more preferably linear C₇-C₁₇ alkyl or alkenyl, most preferably linear C₁₁-C₁₇ alkyl or alkenyl, or a mixture thereof; and Z is a polyhydroxyhydrocarbyl having a linear hydrocarbyl chain wherein at least 3 hydroxyl groups are directly attached to the chain, or an alkoxylated (preferably ethoxylated or propoxylated) derivative thereof. Z is preferably obtained from a reducing sugar in a reductive amination reaction; more preferably Z is a glycityl. Suitable reducing sugars include glucose, fructose, maltose, lactose, galactose, mannose and xylose. As raw materials, high dextrose corn syrup, high fructose corn syrup and high maltose corn syrup as well as the individual sugars listed above can be used. These corn syrups can result in a mixture of sugar components for Z. It should be understood that it is not intended to exclude other suitable raw materials. Z is preferably selected from the group consisting of -CH₂(CHOH)NCH₂OH, -CH(CH₂OH)(CHOH)n-₁-CH₂OH, -CH₂-(CHOH)₂(CHOR")(CHOH)-CH₂OH, wherein n is an integer from 3 to 5 inclusive and R' is H or a cyclic or aliphatic monosaccharide, and the alkoxylated derivatives thereof. Most preferred are glycityls wherein n is 4, especially -CH₂-(CHOH)₄-CH₂OH₂.

In formula (1), R¹ can be, for example, N-methyl, N-ethyl, N-propyl, N-isopropyl, N-butyl, N-2-hydroxyethyl or N-2-hydroxypropyl.

R²-CO-N< can mean, for example, cocoamamide, stearamide, oleamide, lauramide, myristamide, capric acid amide, palmitamide and tallowamide, etc.

Z can stand for 1-deoxyglucityl, 2-deoxyfructityl, 1-deoxymaltityl, 1-deoxylactityl, N-1-deoxygalactityl, N-1- deoxymannityl and 1-deoxymaltotriotityl.

Methods for preparing polyhydroxy fatty acid amides are known in the art. In general, they can be prepared by reacting an alkylamine with a reducing sugar in a reductive amination reaction to form a corresponding N-alkylpolyhydroxyamine, and then reacting the N-alkylpolyhydroxyamine with an aliphatic fatty ester or a triglyceride in a condensation/amidation step to form the N-alkyl,N-polyhydroxy fatty acid amide product. Methods for preparing compositions containing polyhydroxy fatty acid amides are described, for example, in British Patent Specification 809,060, published February 18, 1959, Thomas Hedley & Co., Ltd.; U.S. Patent Specification 2,965,576, issued December 20, 1960, E.R. Wilson, U.S. Patent No. 2,703,798, Anthony M. Schwartz, issued May 8, 1955; and U.S. Patent No. 1,985,424, issued December 25, 1934, Piggott.

In a preferred process for the preparation of N-alkyl or N-hydroxyalkyl, N-deoxyglycityl fatty acid amides, wherein the glycityl component is derived from glucose and the N-alkyl or N-hydroxyalkyl function is N-methyl, N-ethyl, N-propyl, N-butyl, N-hydroxyethyl or N-hydroxypropyl, the product is prepared by reacting N-alkyl or N-hydroxyalkyl glucamine with a fatty ester selected from fatty methyl esters, fatty ethyl esters and fatty triglycerides in the presence of a catalyst selected from the group consisting of trilithium phosphate, trisodium phosphate, tripotassium phosphate, tetrasodium pyrophosphate, pentapotassium tripolyphosphate, lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, disodium tartrate, dipotassium tartrate, sodium potassium tartrate, trisodium citrate, tripotassium citrate, basic sodium silicates, basic potassium silicates, basic Sodium aluminosilicates and basic potassium aluminosilicates and mixtures thereof group. The amount of catalyst is preferably from about 0.5 mole percent to about 50 mole percent, more preferably from about 2.0 mole percent to about 10 mole percent, based on the moles of N-alkyl or N-hydroxyalkyl glucamine. The reaction is preferably carried out at about 138°C to about 170°C for typically about 20 to about 90 minutes. When triglycerides are used in the reaction mixture as the fatty ester source, the reaction is also preferably carried out using from about 1% to about 10% by weight of a phase transfer agent, calculated as a weight percent of the total reaction mixture, selected from saturated fatty alcohol polyethoxylates, alkyl polyglycosides, linear glucamide surfactant, and mixtures thereof.

Preferably, this procedure is carried out as follows:

(a) preheating the fatty ester to about 138ºC to about 170ºC;

(b) adding the N-alkyl or N-hydroxyalkyl glucamine to the heated fatty acid ester and mixing to an extent necessary to form a two-phase liquid/liquid mixture;

(c) mixing the catalyst into the reaction mixture; and

(d) Stir for the stated reaction time.

Also preferably, when the fatty ester is a triglyceride, from about 2% to about 20%, based on the weight of the reactants, of previously formed linear N-alkyl/N-hydroxyalkyl-N-linear glucosyl fatty acid amide product is added to the reaction mixture as a phase transfer agent. This grounds the reaction, thereby increasing the rate of reaction.

These polyhydroxy "fatty acid" amide materials offer the detergent formulator the advantages of being able to be made entirely or predominantly from natural, renewable, non-petrochemical starting materials and of being degradable. They also exhibit low toxicity to aquatic life.

It should be noted that the processes used to prepare the polyhydroxy fatty acid amides of formula (I) usually also involve the production of amounts of non-volatile by-products such as ester amides and cyclic polyhydroxy fatty acid amides. The amount of these by-products will vary depending on the particular reactants and the process conditions. Preferably, the polyhydroxy fatty acid amide incorporated into the detergent compositions of the present invention will be provided in such a form that the composition containing the polyhydroxy fatty acid amide added to the detergent contains less than about 10%, preferably less than about 4%, of cyclic polyhydroxy fatty acid amide. The preferred processes described above are advantageous because they can provide rather small amounts of by-products, including such cyclic amide by-product.

The co-surfactants for the compositions of this invention may also contain mixtures of anionic surfactants and alkyl polyglucosides or polyhydroxy fatty acid amides. The co-surfactants are present in the composition in an amount of from about 35% to about 35%, preferably from about 5% to about 25%, and most preferably from about 7% to about 20% by weight.

Foaming agent

Another component which may be included in the composition of this invention is a foam stabilizing surfactant (a foam booster) in an amount of less than about 15%, preferably from about 0.5% to 12%, more preferably from about 1% to 10%. Optional foam stabilizing surfactants which may be used in the present composition can be classified into five basic types - the betaines, the ethylene oxide condensates, the fatty acid amides, the semipolar amine oxide based nonionics and the cationic surfactants.

The composition of this invention may comprise betaine surfactants of the general formula wherein R represents a hydrophobic group selected from the group consisting of alkyl groups having about 10 to about 22 carbon atoms, preferably about 12 to about 18 carbon atoms, alkylaryl and arylaky groups having a similar number of carbon atoms, with a benzene ring being considered equivalent to about 2 carbon atoms, and similar structures interrupted by amido or ether linkages; each R¹ is an alkyl group having from 1 to about 3 carbon atoms; and each R² is an alkylene group having from 1 to about 6 carbon atoms.

Examples of betaines used are dodecyldimethylbetaine, cetyldimethylbetaine, dodecylamidopropyldimethylbetaine, tetradecyldimethylbetaine, tetradecylamidopropyldimethylbetaine and dodecyldimethylammoniumhexanoate.

Other suitable amidoalkyl betaines are described in US Patent Nos. 3,950,417, 4,137,191 and 4,375,421 and in British Patent GB No. 2,103,236.

It will be understood that the alkyl groups (and acyl groups) of the above betaine surfactants may be obtained from either natural or synthetic sources, e.g., they may be obtained from naturally occurring fatty acids; olefins such as those produced by the Ziegler or oxo process; or from olefins separated from petroleum with or without "cracking".

The ethylene oxide condensates are generally defined as compounds obtained by the condensation of ethylene oxide groups (hydrophilic in nature) with an organic hydrophobic compound, which may be aliphatic or alkylaromatic in nature. The length of the hydrophilic or polyoxyalkylene radical condensed with any single hydrophobic group can be easily adjusted to obtain a water-soluble compound with the desired degree of balance between hydrophilic and hydrophobic elements.

Examples of such ethylene oxide condensates useful as foam stabilizing agents are the condensation products of aliphatic alcohols with ethylene oxide. The alkyl chain of the aliphatic alcohol can be either straight or branched and generally contains from about 8 to about 18, preferably from about 8 to about 14 carbon atoms to achieve best performance as a foam stabilizing agent, the ethylene oxide being used in amounts of from about 8 moles to about 30 moles, preferably from about 8 moles to about 14 moles of ethylene oxide per mole of alcohol.

Examples of surfactants useful herein include the ammonia, monoethanol and diethanol amides of fatty acids having an acyl group of about 8 to about 18 carbon atoms and represented by the general formula:

R₁ -CO-N(H)m-1(R2OH)3-m

wherein R is a saturated or unsaturated aliphatic hydrocarbon radical having about 7 to 21, preferably about 11 to 17 carbon atoms; R2 is a methylene or ethylene group; and m is 1, 2 or 3, preferably 1. Specific examples of the amides mentioned are monoethanolamine coconut fatty acid amide and diethanolamine dodecyl fatty acid amide. These acyl radicals can be derived from naturally occurring glycerides, e.g. coconut oil, palm oil, soybean oil and tallow, but they can also be obtained synthetically, e.g. by the oxidation of petroleum or by the hydrogenation of carbon monoxide by the Fischer-Tropsch process. The monoethanolamides and diethanolamides of C12-14 fatty acids are preferred.

Semipolar, nonionic, amine oxide based surfactants include compounds and mixtures of compounds of the formula

wherein R₁ is an alkyl, 2-hydroxyalkyl, 3-hydroxyalkyl or 3-alkoxy-2-hydroxypropyl radical, wherein the alkyl group or the alkoxy group comprises about 8 to about 18 carbon atoms, R₂ and R₃ are each methyl, ethyl, propyl, isopropyl, 2-hydroxyethyl, 2-hydroxypropyl or 3-hydroxypropyl and n is from 0 to about 10. Particularly preferred are amine oxides of the formula:

wherein R1 is C12-16 alkyl and R2 and R3 are methyl or ethyl. The above ethylene oxide condensates, amides and amine oxides are more fully described in U.S. Patent No. 4,316,824 Panchen).

The composition of this invention may also contain certain cationic quaternary ammonium surfactants of the formula:

[R¹ (OR²)y] [R³(OR²) y]²R⁴N⁺X⁻ or amine surfactants of the formula:

[R¹(OR²)y] [R³(OR²y]R⁴N

wherein R¹ represents an alkyl or alkylbenzyl group having from about 6 to about 16 carbon atoms in the alkyl chain; each R² is selected from the group consisting of -CH₂CH₂-, -CH₂CH(CH₃)-, -CH₂CH(CH₂OH₂)-, -CH₂CH₂CH₂-, and mixtures thereof; each R³ is selected from the group consisting of C₁-C₄ alkyl, C₁-C₄ hydroxyalkyl, benzyl, and is hydrogen when y is not 0; R⁴ has the same meaning as R³ or represents an alkyl chain wherein the total number of carbon atoms of R¹ plus R⁴ is from about 8 to about 16; each y is from 0 to about 10 and the sum of the y values is from to about 15 and X is any compatible anion.

Preferred of the above are the alkyl quaternary ammonium surfactants, particularly the long alkyl chain surfactants described in the above formula when R4 is selected from the same groups as R3. The most preferred quaternary ammonium surfactants are the chloride, bromide and methyl sulfate salts of C8-16alkyltrimethylammonium, C8-16alkyl(dihydroxyethyl)methylammonium, C8-16alkylhydroxyethyldimethylammonium, C8-16alkyloxypropyltrimethylammonium and C8-16alkyloxypropyldihydroxyethylmethylammonium. Of the above, the C₁₀₋₁₄-alkyltrimethylammonium salts are preferred, e.g. decyltrimethylammonium methyl sul-

fat, lauryltrimethylammonium chloride; myistyltrimethylammonium bromide and coconut trimethylammonium chloride and methyl sulfate.

The foam enhancing agents employed in the compositions of this invention may contain any of the foam enhancing agents listed above or a mixture of them.

Additional optional ingredients

In addition to the ingredients described above, the compositions may contain other conventional ingredients suitable for use in liquid or gel dishwashing compositions.

Optional ingredients include drain-promoting, ethoxylated nonionic surfactants of the type described in U.S. Patent No. 4,316,824, Panchen (February 23, 1982).

Alcohols such as ethyl alcohol and propylene glycol can be used to achieve a desired phase stability and viscosity of the product. Alcohols such as ethyl alcohol and propylene glycol are particularly useful in the liquid compositions of this invention in an amount of from 0% to about 15%.

Gel-like compositions of the invention would typically not contain alcohols. These gel-like compositions may contain higher amounts of potassium or sodium toluene, xylene or cumene sulfonate and urea in higher amounts, i.e., from about 10% to about 30%, as gelling agents (see U.S. Patent No. 4,615,819 and GB 2,179,054A).

Other desirable ingredients include diluents and solvents. Diluents can be inorganic salts such as ammonium chloride, sodium chloride and potassium chloride and the solvents include water, low molecular weight alcohols such as ethyl alcohol and isopropyl alcohol. The compositions of the invention will typically contain up to about 80%, preferably about 30% to about 70%, most preferably about 40% to about 65% water.

Unless otherwise indicated, all percentages, parts and ratios as used herein are by weight.

The following examples illustrate the invention and facilitate its understanding.)

example 1

The following liquid composition, which does not illustrate the present invention, is prepared according to the descriptions given below. The alkyl ethoxycarboxylate and the appropriate co-surfactant, foam enhancing agent, ethanol, sodium chloride and buffer are mixed. The pH of the mixture is adjusted to about 8 with ammonium hydroxide. The calcium ions (added as calcium chloride dihydrate) are then added and the pH is finally adjusted to about 7.2 if necessary. Final adjustment of viscosity and minor adjustment of pH can be done at this time, followed by addition of perfume and colorant. The balance is water. *The surfactant mixture contains about 94.2% alkyl ethoxycarboxylates of the formula RO(CH₂CH₂O)xCH₂COO-Na, where R is a C₁₂₋₁₃-alkyl, on average a C₁₂,₅-alkyl; x is from 0 to about 10 and the ethoxylate distribution is such that the amount of material wherein x is 0 is about 1.0 and the amount of material wherein x is greater than 7; is less than about 2 weight percent of the alkyl ethoxycarboxylates. The average value of x in the distribution is 3.5. The surfactant mixture also contains about 5.8% of alcohol ethoxylates of the formula RO(CH2CH2O)xH, wherein R is C12-13 alkyl, on average C12,5 alkyl, and the average value of x is 3.5. The surfactant mixture contains % of soap materials.

The above formulation exhibits an exceptional combination of grease cleaning and mildness and is stable during storage at elevated temperatures (up to 66.7ºC (120ºF)). The cleaning provided by this composition at a pH of about 7.2 to 7.5 is better than that provided by a similar composition containing an equivalent (on a molar basis) amount of magnesium ions. These formulations also provide improved stability during storage, particularly when compared to similar compositions containing magnesium ions.

Example II

The following liquid composition is prepared according to the procedure set forth in Example 1, except that sodium hydroxide is used to adjust the pH of the compositions to about 8.5.

This formulation of the present invention ensures both good grease cleaning in dilute solution and good storage stability of the formulation at elevated temperatures of 66.7ºC (120ºF).

Example III

The following liquid composition is prepared according to the procedure set forth in Example 1, except that sodium hydroxide is used to adjust the pH of the compositions to about 9.5.

This formulation of the present invention provides both good grease cleaning in dilute solution and good storage stability of the formulation at elevated temperatures of 66.7ºC (120ºF), particularly when compared to compositions containing an equivalent amount of magnesium ions.

Example IV

The present liquid composition, which contains a relatively small amount of surfactant and

containing a high amount of calcium ions is prepared according to the procedure given in Example 1.

This formulation of the present invention provides both good grease cleaning in dilute solution and good storage stability of the formulation at elevated temperatures of 66.7°C (120°F), particularly when compared to compositions containing an equivalent amount of magnesium ions. This formulation is particularly useful for dishwashing where a high concentration of product in the solution is used.

Example V

The following four liquid compositions (of which Formulations A, B and C are within the scope of the present invention and Formulation D does not illustrate the present invention) are prepared as described below.

The formulations are prepared by adding ethanol to the alkyl ethoxycarboxylate-containing surfactant. The remaining surfactants are then added and mixed in. The buffers and chelating agents are then added and the pH is adjusted to

approximately 0.5 pH units above the target pH of the formulation with sodium hydroxide. Finally, magnesium chloride is added, which lowers the pH to the target pH. At this point, final viscosity adjustments and minor pH adjustments can be made, followed by the addition of perfume and colorant. The remainder is water.

The surfactant mixture contains about 94.2% alkyl ethoxycarboxylates of the formula RO(CH₂CH₂O)xCH₂COO⁻Na⁺, where R is a C₁₂₋₁₃ alkyl, on average a C₁₂,₅ alkyl; x ranges from 0 to about 10 and the ethoxylate distribution is such that the amount of material where x is 0 is about 1.0 and the amount of material where x is greater than 7 represents less than about 2% by weight of the alkyl ethoxycarboxylates. The average value for x in the distribution is 3.5. The surfactant mixture also contains about 5.8% of alcohol ethoxylates of the formula RO(CH2CH2O)xH, where R is C12-13 alkyl, on average C12,5 alkyl and the average value of x is 3.5. The surfactant mixture contains 0% soap materials.

The above formulations provide an excellent combination of grease cleaning and mildness and do not show precipitation when stored at elevated temperatures (up to 120ºF (66.7ºC)). The grease cleaning ability of these products is directly related to their ability to maintain an alkaline wash pH in dilute solution. The order of these products in terms of their ability to maintain a high wash pH is A>B>C>D. The mildness of these products to the hands is directly related to their amounts of alkyl ethoxycarboxylate-containing surfactant mixture and indirectly related to their amounts of alkyl sulfate and alkyl ethoxysulfate surfactants. For these reasons, the order of these products in terms of mildness to the hands is C>A,B>D. These formulations also provide improved stability during storage compared to similar compositions without buffering and/or chelating agents. However, formulation D contains glycine and shows discoloration of the composition during storage. Example VI The following four liquid compositions are prepared according to the procedure described in Example I. The same alkyl ethoxycarboxylate surfactant mixture as in Example I is used therein.

Formulation B, which is not exemplary of the present invention, provides both good grease cleaning in dilute solution and stability of the formulation when stored at elevated temperatures of 66.7ºC (120ºF). This is in contrast to formulations A, C and D, which are not within the scope of the present invention. Formulation A provides good grease cleaning in dilute solution, even in soft water, due to its combination of alkyl ethoxycarboxylate containing surfactant mixture, magnesium ions and their alkaline pH in a dishwashing solution due to 2-amino-2ethyl-1,3-propanediol. However, formulation A is not stable during storage and precipitates of Mg(OH)2 are formed. Formulation C provides good product stability during storage due to the ability of citrates to prevent precipitation of Mg(OH)2, but does not provide adequate grease cleaning in dilute solution. This is because the amount of citrate is too large and reduces the available Mg⁺⁺ ions in dilute solution required for good cleaning. Similarly, formulation D provides good storage stability but poorer grease cleaning than formulations A and B)

Claims (12)

1. Mild liquid or gel dishwashing detergent composition, characterized in that it contains, by weight, (a) 5% to 70% of a surfactant mixture which, by weight: (i) 80% to 100% of alkyl ethoxycarboxylates of the formula RO (CH₂CH₂O) xCH₂COO⊃min;M⁺, wherein R represents a C12-C16 alkyl group, x ranges from 0 to 10, and the ethoxylate distribution is such that, by weight, the amount of material in which x is less than 20% and the amount of material in which x is greater than 7 is less than 25%, wherein the average value of x is from 2 to 4 when R is on average C13 or shorter and the average value of x is from 3 to 6 when R is on average longer than C13, and M is a cation; (ii) 0% to 10% of alcohol ethoxylates of the formula RO (CH₂CH₂O) xH, wherein R represents a C₁₂-C₁₆ alkyl group and x ranges from 0 to 10 and the average value of x is less than 6; and (iii) 0% to 10% of soaps of the formula RCOO⊃min;M⊃plus;, wherein R represents a C₁₁-C₁₅ alkyl group and M represents a cation; (b) 0.1% to 4% calcium or magnesium ions; (c) a calcium or magnesium chelating agent which forms a soluble calcium or magnesium complex having a logarithm of formation constant, log Kf, of from 0.5 to 5 in an amount sufficient to prevent the formation of calcium carbonate or magnesium hydroxide precipitates in the composition; excluding glycine and citrate; wherein a 10 wt.% aqueous solution of said composition has a pH of 7 to 11. 2) Composition according to claim 1, wherein the surfactant mixture comprises 90% to 95% of alkyl ethoxycarboxylates. 3) Composition according to claim 1 or 2, wherein the pH is from 8 to 10. 4. Composition according to one of the preceding claims, wherein the surfactant mixture comprises less than 5% of alcohol ethoxylates. 5. Composition according to one of the preceding claims, wherein the surfactant mixture comprises less than 5% soaps) 6. A liquid composition according to any preceding claim comprising 12% to 30% of surfactant mixture. 7. Gel-like composition according to one of claims 1 to 5, comprising 10% to 45% of surfactant mixture. 8. A composition according to any preceding claim, further comprising a co-surfactant selected from the group consisting of alkylbenzene sulfonates, alkyl sulfates, paraffin sulfonates, olefin sulfonates, alkyl ether sulfates, fatty acid ester sulfonates, alkyl polyglucosides and polyhydroxy fatty acid amides, and mixtures thereof. 9) A composition according to any preceding claim, further comprising a foam enhancing agent selected from the group consisting of betaines, ethylene oxide condensates, fatty acid amides, semipolar nonionic amine oxides, cationic surfactants, and mixtures thereof. 10) A composition according to any preceding claim, which further comprises a sufficient amount of alkalinity buffering Means to maintain the pH of the composition between 8 and 10. 11. A composition according to any preceding claim, wherein the calcium or magnesium chelating agent is selected from the group consisting of sarcosine, bicine, N-(2-hydroxyethyl) iminodiacetic acid, N-(2,3- dihydroxypropyl) iminodiacetic acid and their alkali metal salts, and mixtures thereof. 12. The composition of claim 10, wherein the buffer is selected from the group consisting of N-methyldiethanolamine, 1,3-diamino-2-propanol, bicine, N,N'-tetramethyl-1,3-diamino-2-propanol.