Foaming dishwashing liquid compositions

This invention relates to dishwashing liquid detergent compositions which provide controllable aqueous foams.

Alkylpolyglycosides which are surfactants have been disclosed in U.S.Patents 3,598,865; 3,721,633 and 3,772,269. These patents also disclose processes for making alkylpolyglycoside surfactants and built liquid detergent compositions containing these surfactants. U.S. Patent 3,219,656 discloses alkylmonoglucosides and suggests their utility as foam stabilisers for other surfactants. Various polyglycoside surfactant structures and processes for making them are disclosed in U.S. Patents 2,974,134, 3,640,998, 3,839,318, 3,314,936, 3,346,558, 4,011,389, 4,223,129.

Foaming compositions containing an alkylpolysaccharide surfactant, an anionic cosurfactant and possibly an auxiliary foam booster, are described in copending published EP-A-0070076 and EP-A-0070074.

Light duty detergent compositions containing an alkylpolysaccharide, alkylbenzene sulfonate and al- kylpolyethoxylate sulfate cosurfactants are described in published EP-A-0070077.

All percentages, parts and ratios used herein are by weight unless otherwise specified.

This invention relates to foaming dishwashing liquid detergents comprising 10-50% by weight of the composition of

• (1) an alkyl polyglucoside of the formula R²0(C_nH_2nO)_t(Z)_x wherein Z is derived from glucose, R² is a hydrophobic saturated alkyl group containing from 12 to 18, preferably from 12 to 14 carbon atoms; n is 2 or 3, preferably 2, t is from 0 to 10, preferably 0; and x is from 1.5 to 4, preferably from 1.6 to 2.7, and including less than 10% unreacted fatty alcohol and less than 50% short chain alkyl polyglucoside and
• (2) a mixture of aniomic cosurfactants neutralised with one or more cationic moieties consisting essentially of:

  • (a) from 1 to 95%, preferably from 10 to 50%, of a water-soluble alkylbenzene sulfonate in which the alkyl group contains from 10 to 13 carbon atoms, and
  • (b) from 5 to 99%, preferably from 50-90%, of a cosurfactant selected from the group consisting of an alkyl glyceryl ether sulfonate in which the alkyl group contains from 8 to 18 carbon atoms, an alphaolefin sulfonate in which the olefin group contains atom 10 to 18 carbon atoms, an alkyl polyethoxylate carboxylate in which the alkyl group contains from 10 to 18 carbon atoms, and the polyethoxylate chain contains from 2 to 6 ethoxylate groups, and mixtures thereof, the weight ratio (2) : (1) being from 1 : 10 to 10 : 1.

It has surprisingly been found that the cosurfactants interact with the alkylpolyglucoside surfactant of this invention to provide a relatively stable foam which is readily rinsed and in particular that gives good suds mileage and "Suds During Washing" values.

The alkylpolyglucosides are those having an alkyl hydrophobic group that is saturated and that contains from 12 to 18 carbon atoms, preferably from 12 to 16 carbon atoms, most preferably from 12 to 14 carbon atoms. The number x indicates the number of glucoside units in a particular alkylpolyglucoside surfactant. For a particular alkylpolyglucoside molecule x can only assume integral values. In any physical sample of alkypolyglucoside surfactants there will in general be molecules having differentxvalues. The physical sample can be characterised by the average value of x and this average value can assume non-integral values. In this specification the values of are to be understood to be average values. The hydrophobic group (R²) can be attached at the 2-, 3-, or 4-positions rather than at the 1-position, (thus giving e.g. a glucosyl as opposed to a glucoside). However, attachment through the 1-position, i.e., glucosides, is preferred. In the preferred product the additional glucoside unit's are predominately attached to the previous glucoside units 2-position. Attachment through the 3-,4-, and 6- positions can also occur.

Optionnaly, and less desirably there can be a polyalkoxide chain joining the hydrophobic moiety R² and the polyglucoside chain. The preferred alkoxide moiety is ethoxide.

Suitable alkyl polyglucosides are dodecyl, tetradecyl, hexadecyl, and octadecyl, di-, tri- and tetraglucosides.

The alkylmonoglucosides are relatively less soluble in water than the higher alkylpolyglucosides. When used in admixture with alkylpolyglucosides the alkylmonoglucosides are solubilised to some extent. The use of alkylmonoglucosides in admixture with alkylpolyglucosides is a preferred mode of carrying out the invention. Suitable mixtures include coconut alkyl, di-, tri- and tetraglucosides and tallow alkyl tetraglucosides.

To prepare these compounds a long chain alcohol (R²0H) can be reacted with glucose, in the presence of an acid catalyst to form the desired glucosides. Alternatively the alkylpolyglucosides can be prepared by a two step procedure in which a short chain alcohol (C_l-₆) is reacted with glucose or a polyglucoside (x=2 to 4) to yield a short chain alkyl glucoside (x=1 to 4) which can in turn be reacted with a longer chain alcohol (R²0H) to displace the short chain alcohol and obtain the desired alkylpolyglucoside. If this two step procedure is used, the short chain alkylglucoside content of the final alkylpolyglucoside material should be less than 50%, preferably less than 10%, more preferably less than 5%, most preferably 0% of the alkylpolyglucoside. The amount of unreacted alcohol (the free fatty alcohol content) in the desired alkylpolyglucoside surfactant is preferably less than 2% more preferably less than 0.5% by weight of the total of the alkyl polyglucoside plus unreacted alcohol. The amount of alkylmonoglucoside is 20% to 70%, preferably 30% to 60%, most preferably 30% to 50% by weight of the total of the alkylpolyglucoside. For some uses it is desirable to have the alkylmonoglucoside content less than 10%. Throughout this specification, "alkylglucoside" is used to include alkylglycosides because the stereochemistry of the saccharides moiety is changed during the preparation reaction.

Anionic cosurfactants can be selected from the group consisting of sulfonates, carboxylates and mixtures thereof. The cosurfactants are neutralised with a cationic moiety or moieties selected from the group consisting of alkali metal, e.g. sodium or potassium, alkaline earth metal, e.g. calcium or magnesium, ammonium, substituted ammonium, including mono-, di-, or tri-, ethanolammonium cations. Mixtures of cations can be desirable. The anionic cosurfactants useful in the present invention all have detergent properties and are all water soluble or dispersible in water.

One of the cosurfactants for use in this invention. is an alkylbenzene sulfonate. The alkyl group can be either saturated or unsaturated, branched or straight chain and is optionally substituted with a hydroxy group. Middle phenyl positions are generally preferred for volume of foaming in tight soil conditions. However, in heavier soil conditions, phenyl attachment at the 1-or 2-position is preferred.

The preferred alkylbenzene sulfonates contain a straight alkyl chain containing from 10 to 13 carbon atoms, and the cation is sodium, potassium, ammonium, mono-, di-, or triethanolammonium, calcium or magnesium and mixtures thereof. Magnesium is the preferred cationic moiety. These same cations are preferred for other anionic surfactants and ingredients. The magnesium alkylbenzene sulfonates where the phenyl group is attached near the middle of the alkyl chain are surprisingly better than the ones with the phenyl near the end of the chain when the polysaccharide chain averages greater than 3 saccharide units. Suitable alkylbenzene sulfonates include C₁₁ alkylbenzene sulfonates with low 2-phenyl content.

Many other surfactants which contain sulfonate or carboxylate groups can be used in the foaming compositions of the invention. Generally the use of these latter cosurfactants produces less foam volume than does the use of the preferred cosurfactants. However, the alkylpolyglucoside surfactant stabilises the foams which are produced and allows the foams to be rinsed more quickly.

One group of cosurfactants that are of interest because of their superior detergency are the zwitterionic detergents which contain both a cationic group, either ammonium, phosphonium, sulfonium or mixtures thereof and a sulfonate or carboxylate group. Preferably there are at least four atoms separating the cationic and anionic groups. Suitable zwitterionic surfactant are disclosed in U.S.Patents 4,159,277; 3,928,251; 3,925,262, 3,929,678; 3,227,749; 3,539,521; 3,383,321, 3,390,094, and 3,239,560.

Another group of cosurfactants are the amphoteric detergents which have the same general structure as the zwitterionic surfactants but with an amine group instead of the quaternary ammonium group.

Yet other cosurfactants are the alkyl (paraffin or olefin) sulfonates, preferably with a more central hydrophilic group, containing from 6 to 30 carbon atoms. Compositions containing these cosurfactants produce the least volume of foam, if that is desired. The hydrophobic group can contain up to 10 hydroxy groups and/or ether linkages. Examples include ^C14-15 paraffin sulfonates and C₁₄-₁₆ olefin sulfonates.

Still another cosurfactant is a soap structure containing up to 10 ether linkages in the chain and from 1 to 4 carbon atoms between ether linkages with from 6 to 30 carbon atoms in a terminal portion containing no ether linkages.

The alkylpolyglucosides can be contaminated with less than 50% short chain alkylpolyglucosides and with less than 10%, preferably less than 2%, most preferably less than 0.5% unreacted fatty alcohol and increase the sudsing abilily of conventional sulfate detergent cosurfactants, especially alkyl sulfate and alkyl polyether sulphate cosurfactants having he formula:

wherein R³ is an alkyl or hydroxyalkyl group containing from 8 to 18 carbon atoms, n is 2 or 3, t can vary from 0 to 30, and M is a cationic moiety as defined above, the cosurfactant being watersoluble ordisper- sible.

Such compostions have improved suds mileage as compared to compositions containing only the alkyl benzene sulfonate cosurfactant and the alkylpolyglucoside surfactant.

Typical compositions for use as light duty liquid detergent compositions in washing dishes comprise from 10% to 50%, preferably from 10% to 40% of the mixture of surfactants disclosed hereinbefore and from 1 % to 50% of a solvent selected from the group consisting of C_1-3 alkanols, C_1-3 alkanolamines, C₂-₄ polyols, mixtures thereof, and the balance water. It is a special advantage of the compositions of this invention that they can be made in concentrated form (up to 50% by wt, of the mixture of surfactants) with only very low levels of organic solvents and without the addition of expensive hydroptropic materials. Fatty alcohols should not be used.

The compositions of this invention can utilise other compatible ingredients, including other surfactants, in addition to the mixture of surfactants herein disclosed.

The following nonlimiting examples illustrate the foaming compositions of the present invention.

The relative volume of suds in ml is determined by the following test procedure:

100mi of the test solution at 44.5°C is placed in a 500ml graduated cylinder: the solution is agitated by repeated inversion of the graduated cylinder until the amount of suds in the cylinder does not increase with further agitation. Suds height is measured directly on the cylinder scale making allowance for the height of liquid remaining in the cylinder. The test solution is made by adding the test product to water having a hardness of 0.12 gram per liter (Ca/Mg=3/1).

Example 1

Ammonium C_11.2 linear alkyl benzene sulfonate was admixed with C₁₂ alkylpolyglucoside G₃.₅ in a ratio of 2:1. The mixture was used at a level of 400ppm in city water. The initial suds volume was more than 300ml, but after the addition of about 1.25 grams of a standard grease soil per 200 ml of wash solution, the suds had disappeared. Substitution of a sodium C₁₂-₁₆ alkyl glyceryl ether sulfonate for 25% and 40% of the mixture extended the point at which there was no suds to 1.5 and 1.75 grams of soil per 200ml of wash solution respectively.

Similar results are obtained when a sodium, potassium, ammonium, or monoethanol-ammonium C_12-16alkylpolyethoxy₃ acetate, or C_14-16 olefin sulfonate or mixtures thereof is substituted for at least part of the alkyl glyceryl ether sulfonate.

Example 2

A2:1 mixture of an ammonium C_11.2 alkyl benzene sulfonate and the C₁₂-₁₃ alkylpolyglucoside (2-4) ( >2% free fatty alcohol) are tested for suds volume as described hereinbefore. The initial suds volume is good, but the SDW (Suds During Washing) grade is not a good as some premium commercial products. Substitution of between 25% and 50% of the mixture with a sodium C₁₂-₁₆ alkyl glyceryl ether sulfonate, or sodium C_14-16 olefin sulfonate, or sodium C₁₂-₁₃ alkyl polyethoxylate (3) acetate increases the SDW grade without lowering the initial sudsing excessively.

Known analytical techniques can be used to determine the structures of the alkylpolyglucoside surfactants herein; for example, to determine the glycosidic chain length, the amount of butyl glucoside, the free fatty alcohol content, and the level of unreacted polyglucoside. More specifically, gas or liquid chromatography can be used to determine the unreacted alcohol content and the unreacted polyglucoside content respectively. Proton nmr can be used to determine the average glucosidic chain length. The point of attachment of the hydrophilic portion of the molecule to the hydrophobic portion of the molecule can be determined by ¹³C nmr.

The alkypolyglucoside surfactants are complex mixtures. Their components vary depending upon the nature of the starting materials and the reaction by which they are prepared. Analytical standards which are useful in calibrating instruments for analysing the components of a particular alkylpolyglucoside surfactant can be obtained from Calbiochem Behring Co. LaJolla, California. These standards include those for octylglucoside (Calbiochem #494559), decylgluco- side (Calbiochem #252715), dodecylmaltoside (Calbiochem #3243555).