GB2311537A - Rinse composition for dishwashers - Google Patents

Description

RINSING COMPOSITIONS Technical Field The present invention relates to rinsing (rinse aid) compositions, particularly acidic rinsing compositions containing an amino tricarboxylic acid.

Background of the Invention Rinse aid compositions designed for use in automatic dishwasher machines are well known. These compositions are added during the rinsing cycle of the machine, separately from the detergent composition employed in the main wash cycle(s). The ability to enhance rinsing, and in particular the ability to prevent spot and film formation are common measures of rinse aid performance.

Rinse aid compositions typically contain components such as nonionic surfactants and/or hydrotropes which aid the wetting of the items in the rinse, thereby improving the efficacy of the rinsing process. These surfactants, and rinse aid compositions in general, are not designed for the achievement of a primary soil removal purpose.

The general problem of the formation of deposits as spots and films on the articles in the wash/rinse, and on the dishwasher machine parts is well known in the art.

Whilst the general problem of deposit formation is known, a full understanding of the many facets of the problem is however still an active area of research.

A range of deposit types can be encountered. The redeposition of soils or the breakdown products thereof, which have previously been removed from the soiled tableware in the washload, provides one deposit type. Insoluble salts such as calcium phosphate or carbonate, calcium fatty acid salts (lime soaps), or certain silicate salts are other common deposit types. Composite deposit types are also common. Indeed, once an initial minor deposit forms it can act as a "seeding centre" for the formation of a larger, possibly composite, deposit structure.

Deposit formation can occur on a range of commonly encountered substrate surfaces including plastic, glass, metal and china surfaces. Certain deposit types however, show a greater propensity to deposit on certain substrates.

For example, lime soap deposit formation tends to be a particular problem on plastic substrates.

The formation of insoluble carbonate and phosphate, especially calcium carbonate and phosphate, deposits are a particular problem in the machine dishwashing art. The Applicants have found that the formation of insoluble salt deposits occur most noticeably in the rinse cycle of the dishwasher machine. Deposit build up is most apparent on the heater element of the dishwasher machine.

The Applicants have found that the problem of insoluble salt deposit formation may be effectively ameliorated by the inclusion of amino tricarboxylic acid (ATCA) into a rinse aid formulation.

The Applicants have also found that ATCA can bind magnesium ions reducing the formation of insoluble magnesium salts, such as magnesium silicate on the articles in the wash.

The Applicants have also found that the more effective control of calcium carbonate and phosphate deposition can also lead to benefits in the prevention of the formation of other deposit types, particularly lime soap deposits and silicate deposits.

Lime soap deposits are most commonly encountered when the washload contains fatty soils, which naturally contain levels of free fatty acids, and when lipolytic enzymes are components of the formulation. Lipolytic enzymes catalyse the degradation of fatty soils into free fatty acids and glycerol. Silicate is a common component of machine dishwashing formulations, where it is added for its china care capability.

Summarv of the Invention There is provided a rinse aid composition containing an amino tricarboxylic acid or its salts or complexes having the general formula:

where R1, R2 and R3 are alkyl groups or substituted alkyl groups of chain length C1 toC4;nis0or 1; and X is an organic substituent group.

The pH of said composition as a 1% solution in distilled water at 200C is preferably less than 7.

Detailed Description of the Invention Amino Tricarboxvlic Acid (ATCA) The first essential component of the compositions in accord with the invention is an amino tricarboxylic acid or one of its salts or complexes.

The amino tricarboxylic acid (ATCA) is selected from the group having the general formula as shown below.

where R1, R2 and R3 are an alkyl group or substituted alkyl group of chain length C1 to C4, and n is 0 or 1. X is an organic substitutent group, that is a substituent typically encountered in organic compounds, but excluding X being a hydrogen substituent. X can thus for example be an alkyl, aryl, alkenyl or alkaryl group optionally substituted by any functionality including for example, amino, hydroxyl, amide and ether functionalities. X may also be an organic functional group including for example an amine, hydroxyl, amide, ester or ether group. X is preferably an alkyl group, most preferably a methyl or ethyl group. ATCA is most preferably methyl glycine diacetic acid, that is where R1 = R2 = a -CH-2 group, n is 0 and X = CH3.

ATCA can be present at levels of greater than 0.5% by weight, preferably from 0.5 % to 40% by weight, most preferably from 1% to 15% by weight of the rinsing composition.

ATCA acts as a cation complexing chelant. ATCA forms water-soluble chelates with calcium, magnesium, lead, copper, zinc, cadmium, mercury, manganese, iron, aluminium and other cationic polyvalent ions. The stability constant (measured as log K MeZ) of ATCA-calcium chelate is greater than 5.0, preferably greater then 6.0. The stability constant of the preferred ATCA compound, methyl glycine diacetic acid (MGDA) is 7.0. The stability constant, log K MeZ is measured in a solution of ionic strength of 0.1, at a temperature of 25"C. The figure of > 5.0 for 1 gKMeZ indicates that the ratio of the concentration of the undissociated [CaATCA-] to the dissociated complex [Ca2+]EATCA3-], is > 105:1 The ATCA component may be present in its acid form or in the form of one of its salts or complexes with a suitable counter cation.

Preferably any salts/complexes are water soluble, with the alkali metal and alkaline earth metal salts/complexes being especially preferred.

pH of the compositions In a highly preferred aspect of the invention the compositions have a pH as a 1% solution in distilled water at 20OC of less than 7, preferably from 0.5 to 6.5, most preferably from 1.0 to 5.0.

The pH of the compositions may be adjusted by the use of various pH adjusting agents. Preferred acidification agents include inorganic and organic acids including, for example, carboxylate acids, such as citric and succinic acids, polycarboxylate acids, such as polyacrylic acid, and also acetic acid, boric acid, malonic acid, adipic acid, fumaric acid, lactic acid, glycolic acid, tartaric acid, tartronic acid, maleic acid, their derivatives and any mixtures of the foregoing.

Bicarbonates, particularly sodium bicarbonate, are useful pH adjusting agents herein. A highly preferred acidification acid is citric acid which has the advantage of providing builder capacity to the wash solution.

Heaw metal ion sequestrants Heavy metal ion sequestrants are useful components herein. By heavy metal ion sequestrants it is meant components which act to sequester (chelate) heavy metal ions. These components may also have calcium and magnesium chelation capacity, but preferentially they bind heavy metal ions such as iron, manganese and copper.

Heavy metal ion sequestrants are preferably present at a level of from 0.005% to 20%, more preferably from 0.1% to 10%, most preferably from 0.2% to 5% by weight of the compositions.

Heavy metal ion sequestrants, which are acidic in nature, having for example phosphonic acid or carboxylic acid functionalities, may be present either in their acid form or as a complex/salt with a suitable counter cation such as an alkali or alkaline metal ion, ammonium, or substituted ammonium ion, or any mixtures thereof. Preferably any salts/complexes are water soluble. The molar ratio of said counter cation to the heavy metal ion sequestrant is preferably at least 1:1.

Suitable heavy metal ion sequestrants for use herein include the organo aminophosphonates, such as the amino alkylene poly (alkylene phosphonates) and nitrilo trimethylene phosphonates. Preferred organo aminophosphonates are diethylene triamine penta (methylene phosphonate) and hexamethylene diamine tetra (methylene phosphonate).

Other suitable heavy metal ion sequestrants for use herein include nitrilotriacetic acid and polyaminocarboxylic acids such as ethylenediaminotetracetic acid, ethylenetriamine pentacetic acid, or ethylenediamine disuccinic acid. Especially preferred is ethylenediamine-N,N'-disuccinic acid (EDDS), most preferably present in the form of its S,S isomer, which is preferred for its biodegradability profile.

Still other suitable heavy metal ion sequestrants for use herein are iminodiacetic acid derivatives such as 2-hydroxyethyl do acetic acid or glyceryl imino diacetic acid, described in EPA 317 542 and EPA 399 133.

Low molecular weight acrylic acid containing organic polymer The compositions in accord with the invention may contain as a preferred component an organic polymer containing acrylic acid or its salts having an average molecular weight of less than 15,000, hereinafter referred to as low molecular weight acrylic acid containing polymer. Such low molecular weight acrylic acid containing polymers may act as CaC03 dispersants, and thus further enhance the CaCO3 deposition prevention capability of the compositions herein.

The low molecular weight acrylic acid containing polymer has, an average molecular weight of less than 15,000, preferably from 500 to 12,000, more preferably from 1,500 to 10,000, most preferably from 2,500 to 9,000.

The low molecular weight acrylic acid containing organic polymer is preferably present at a level of from 0.005% to 20%, more preferably from 0.1% to 10%, most preferably from 0.2% to 5% by weight of the compositions.

The low molecular weight acrylic acid containing polymer may be either a homopolymer or a copolymer including the essential acrylic acid or acrylic acid salt monomer units. Copolymers may include essentially any suitable other monomer units including modified acrylic, fumaric, maleic, itaconic, aconitic, mesaconic, citraconic and methylenemalonic acid or their salts, maleic anhydride, acrylamide, alkylene, vinylmethyl ether, styrene and any mixtures thereof.

Preferred commercially available low molecular weight acrylic acid containing homopolymers include Sokalan PA30, PA20, PA15 and PAlO by BASF GmbH, and those sold under the tradename Acusol 45N by Rohm and Haas.

Preferred low molecular weight acrylic acid containing copolymers include those which contain as monomer units: a) from about 90% to about 10%, preferably from about 80% to about 20% by weight acrylic acid or its salts and b) from about 10% to about 90%, preferably from about 20% to about 80% by weight of a substituted acrylic monomer or its salts having the general formula -[CR2-CRl (CO-O-R3)]- wherein at least one of the substituents R1, R2 or R3, preferably R1 or R2 is a 1 to 4 carbon alkyl or hydroxyalkyl group, R1 or R2 can be a hydrogen and R3 can be a hydrogen or alkali metal salt. Most preferred is a substituted acrylic monomer wherein R1 is methyl, R2 is hydrogen. The most preferred copolymer of this type has a molecular weight of 3500 and contains 60% to 80% by weight of acrylic acid and 40% to 20% by weight of methyl acrylic acid.

Preferred commercially available low molecular weight acrylic acid containing copolymers include those sold under the tradename Sokalan CP10 by BASF.

Other suitable polyacrylate/modified polyacrylate copolymers include those copolymers of unsaturated aliphatic carboxylic acids disclosed in U.S.

Patents No.s 4,530,766, and 5,084,535 which have a molecular weight of less than 15,000 in accordance with the invention.

Additional organic polvmeric compound Certain additional organic polymeric compounds may be added to the rinse aid compositions of the invention, however, in certain cases their presence is desirably minimized. By additional organic polymeric compounds it is meant essentially any polymeric organic compounds commonly used as dispersants, anti-redeposition and soil suspension agents in detergent compositions, which do not fall within the definition of low molecular weight acrylic acid containing polymers given hereinbefore.

Additional organic polymeric compound may be incorporated into the rinse aid compositions of the invention at a level of from 0.05% to 30%, preferably from 0.5% to 15%, most preferably from 1% to 10% by weight of the compositions.

Examples of additional organic polymeric compounds whose presence is desirably minimized, and which are preferably not present, include the water soluble organic homo- or co-polymeric polycarboxylic acids or their salts in which the polycarboxylic acid comprises at least two carboxyl radicals separated from each other by not more than two carbon atoms. Polymers of the latter type are disclosed in GB-A1,596,756. Examples of such salts are the copolymers of polyacrylate with maleic anhydride having a molecular weight of from 20,000 to 150,000, especially about 40,000 to 80,000.

The polyamino compounds are useful herein including those derived from aspartic acid such as those disclosed in EP-A-305282, EP-A305283 and EP-A-351629.

Other additional organic polymeric compounds suitable herein include cellulose derivatives such as methyl cellulose, carboxymethylcellulose and hydroxyethylcellulose.

Further useful additional organic polymeric compounds are the polyethylene glycols, particularly those of molecular weight 100010000, more particularly 2000 to 8000 and most preferably about 4000.

Detergent Builder Svstem A highly preferred component of the rinsing compositions of the present invention is a detergent builder system which is preferably present at a level of from 0.5% to 60% by weight, more preferably from 1% to 30% by weight, most preferably from 2% to 20% weight of the composition.

The detergent builder system is preferably water-soluble, and preferably contains a carboxylate or polycarboxylate builder containing from one to four carboxy groups, particularly selected from monomeric polycarboxylates or their acid forms, homo or copolymeric polycarboxylic acids or their salts in which the polycarboxylic acid comprises at least two carboxylic radicals separated from each other by not more that two carbon atoms.

The detergent builder system can contain alkali metal, ammonium or alkanonammonium salts of bicarbonates, borates, phosphates, and mixtures of any of the foregoing.

Preferably, the detergent builder system contains no phosphate builder compound.

Carboxvlate or polvcarboxvlate builder Suitable water-soluble monomeric or oligomeric carboxylate builders can be selected from a wide range of compounds but such compounds preferably have a first carboxyl logarithmic acidity/constant (pK1) of less than 9, preferably of between 2 and 8.5, more preferably of between 4 and 7.5.

The carboxylate or polycarboxylate builder can be momomeric or oligomeric in type although monomeric polycarboxylates are generally preferred for reasons of cost and performance. Monomeric and oligomeric builders can be selected from acyclic, alicyclic, heterocyclic and aromatic carboxylates.

Suitable carboxylates containing one carboxy group include the water soluble salts of lactic acid, glycolic acid and ether derivatives thereof as disclosed in Belgian Patent Nos. 831,368, 821,369 and 821,370.

Polycarboxylates containing two carboxy groups include the watersoluble salts of succinic acid, malonic acid, (ethylenedioxy) do acetic acid, maleic acid, diglycolic acid, tartaric acid, tartronic acid and fumaric acid, as well as the ether carboxylates described in German Offenlegenschrift 2,446,686, and 2,446,687 and U.S. Patent No.

3,935,257 and the sulfinyl carboxylates described in Belgian Patent No. 840,623. Polycarboxylates containing three carboxy groups include, in particular, water-soluble citrates, aconitrates and citraconates as well as succinate derivatives such as the carboxymethyloxysuccinates described in British Patent No.

1,379,241, lactoxysuccinates described in British Patent No.

1,389,732, and aminosuccinates described in Netherlands Application 7205873, and the oxypolycarboxylate materials such as 2-oxa-1,1,3- propane tricarboxylates described in British Patent No. 1,387,447.

Polycarboxylates containing four carboxy groups include oxydisuccinates disclosed in British Patent No. 1,261,829, 1,1,2,2ethane tetracarboxylates, 1,1,3,3-propane tetracarboxylates and 1,1,2,3-propane tetracarboxylates. Polycarboxylates containing sulfo substituents include the sulfosuccinate derivatives disclosed in British Patent Nos. 1,398,421 and 1,398,422 and in U.S. Patent No.

3,936,448, and the sulfonated pyrolysed citrates described in British Patent No. 1,439,000.

Alicyclic and heterocyclic polycarboxylates include cyclopentanecis,cis,cis-tetracarboxylates, cyclopentadienide pentacarboxylates, 2,3,4,5-tetrahydrofuran - cis, cis, cis-tetracarboxylates, 2,5 tetrahydrofliran - cis - dicarboxylates, 2,2,5,5-tetrahydrofuran tetracarboxylates, 1,2,3,4,5,6-hexane - hexacarboxylates and carboxymethyl derivatives of polyhydric alcohols such as sorbitol, mannitol and xylitol. Aromatic polycarboxylates include mellitic acid, pyromellitic acid and the phthalic acid derivatives disclosed in British Patent No. 1,425,343.

Of the above, the preferred polycarboxylates are hydroxycarboxylates containing up to three carboxy groups per molecule, more particularly citrates, especially sodium citrate.

The parent acids of the monomeric or oligomeric polycarboxylate chelating agents or mixtures thereof with their salts, e.g. citric acid or citrate/citric acid mixtures are also contemplated as components of builder systems of the compositions in accordance with the present invention.

Phosphate builder compound Specific examples of phosphate builders are the alkali metal tripolyphosphates, sodium, potassium and ammonium pyrophosphate, sodium and potassium and ammonium pyrophosphate, sodium and potassium orthophosphate, sodium polymeta/phosphate in which the degree of polymerization ranges from about 6 to 21, and salts of phytic acid. Preferably, no phosphate builder compound is present.

Surfactant system A highly preferred component of the compositions of the invention is a surfactant system comprising surfactant selected from anionic, cationic, nonionic ampholytic and zwitterionic surfactants and mixtures thereof.

The surfactant system most preferably comprises low foaming nonionic surfactant, selected for its wetting ability, preferably selected from ethoxylated and/or propoxylated nonionic surfactants, more preferably selected from nonionic ethoxylated/propoxylated fatty alcohol surfactants.

When the surfactant system comprises low foaming nonionic surfactant the compositions preferably contain no additional suds suppressor components, such as silicone suds suppressors as can be found in certain machine dishwashing detergent compositions.

The surfactant system is typically present at a level of from 0.5% to 40% by weight, more preferably 1% to 30% by weight, most preferably from 5% to 20% by weight of the compositions.

Anionic surfactant Essentially any anionic surfactants useful for detersive purposes can be included in the compositions. These can include salts (including, for example, sodium, potassium, ammonium, and substituted ammonium salts such as mono-, di- and triethanolamine salts) of the anionic sulfate, sulfonate, carboxylate and sarcosinate surfactants.

Other anionic surfactants include the isethionates such as the acyl isethionates, N-acyl taurates, fatty acid amides of methyl tauride, alkyl succinates and sulfosuccinates, monoesters of sulfosuccinate (especially saturated and unsaturated C1 2-C18 monoesters) diesters of sulfosuccinate (especially saturated and unsaturated C6-C14 diesters), N-acyl sarcosinates.

Resin acids and hydrogenated resin acids are also suitable, such as rosin, hydrogenated rosin, and resin acids and hydrogenated resin acids present in or derived from tallow oil.

Anionic sulfate surfactant Anionic sulfate surfactants suitable for use herein include the linear and branched primary alkyl sulfates, alkyl ethoxysulfates, fatty oleyl glycerol sulfates, alkyl phenol ethylene oxide ether sulfates, the Cs-C17 acyl-N-(C 1 - C4 alkyl) and -N-(C 1 -C2 hydroxyalkyl) glucamine sulfates, and sulfates of alkylpolysaccharides such as the sulfates of alkylpolyglucoside (the nonionic nonsulfated compounds being described herein).

Alkyl ethoxysulfate surfactants are preferably selected from the group consisting of the C6-C18 alkyl sulfates which have been ethoxylated with from about 0.5 to about 20 moles of ethylene oxide per molecule. More preferably, the alkyl ethoxysulfate surfactant is a C6-C18 alkyl sulfate which has been ethoxylated with from about 0.5 to about 20, preferably from about 0.5 to about 5, moles of ethylene oxide per molecule.

Anionic sulfonate surfactant Anionic sulfonate surfactants suitable for use herein include the salts of C- C20 linear alkylbenzene sulfonates, alkyl ester sulfonates, C6-C22 primary or secondary alkane sulfonates, C6-C24 olefin sulfonates, sulfonated polycarboxylic acids, alkyl glycerol sulfonates, fatty acyl glycerol sulfonates, fatty oleyl glycerol sulfonates, and any mixtures thereof.

Anionic carboxylate surfactant Anionic carboxylate surfactants suitable for use herein include the alkyl ethoxy carboxylates, the alkyl polyethoxy polycarboxylate surfactants and the soaps ('alkyl carboxyls'), especially certain secondary soaps as described herein.

Preferred alkyl ethoxy carboxylates for use herein include those with the fomula RO(CH2CH20)x CH2C0O-M+ wherein R is a C6 to C18 alkyl group, x ranges from 0 to 10, and the ethoxylate distribution is such that, on a weight basis, the amount of material where x is 0 is less than about 20 %, and the amount of material where x is greater than 7, is less than about 25 %, the average x is from about 2 to 4 when the average R is C13 or less, and the average x is from about 3 to 10 when the average R is greater than C13, and M is a cation, preferably chosen from alkali metal, alkaline earth metal, ammonium, mono-, di-, and tri-ethanol-ammonium, most preferably from sodium, potassium, ammonium and mixtures thereof with magnesium ions. The preferred alkyl ethoxy carboxylates are those where R is a C12 to C18 alkyl group.

Alkyl polyethoxy polycarboxylate surfactants suitable for use herein include those having the formula RO-(CHRI-CHR2-O)-R3 wherein R is a C6 to C18 alkyl group, x is from 1 to 25, R1 and R2 are selected from the group consisting of hydrogen, methyl acid radical, succinic acid radical, hydroxysuccinic acid radical, and mixtures thereof, wherein at least one R1 or R2 is a succinic acid radical or hydroxysuccinic acid radical, and R3 is selected from the group consisting of hydrogen, substituted or unsubstituted hydrocarbon having between 1 and 8 carbon atoms, and mixtures thereof.

Preferred soap surfactants are secondary soap surfactants which contain a carboxyl unit connected to a secondary carbon. The secondary carbon can be in a ring structure, e.g. as in p-octyl benzoic acid, or as in alkylsubstituted cyclohexyl carboxylates. The secondary soap surfactants should preferably contain no ether linkages, no ester linkages and no hydroxyl groups. There should preferably be no nitrogen atoms in the head-group (amphiphilic portion). The secondary soap surfactants usually contain 11-13 total carbon atoms, although slightly more (e.g., up to 16) can be tolerated, e.g. p-octyl benzoic acid.

The following general structures further illustrate some of the preferred secondary soap surfactants: A. A highly preferred class of secondary soaps comprises the secondary carboxyl materials of the formula R3 CH(R4)COOM, wherein R3 is CH3(CH2)x and R4 is CH3(CH2)y, wherein y can be O or an integer from 1 to 4, x is an integer from 4 to 10 and the sum of(x + y) is 6-10, preferably 7-9, most preferably 8.

B. Another preferred class of secondary soaps comprises those carboxyl compounds wherein the carboxyl substituent is on a ring hydrocarbyl unit, i.e., secondary soaps of the formula R5-R6-COOM, wherein R5 is C7-C10, preferably C8-C9, alkyl or alkenyl and R6 is a ring structure, such as benzene, cyclopentane and cyclohexane. (Note: R5 can be in the ortho, meta or para position relative to the carboxyl on the ring.) C. Still another preferred class of secondary soaps comprises secondary carboxyl compounds of the formula CH3 (CHR)k(CH2)m-(CHR)n-CH(COOM)(CHR)o-(CH2)p-(CHR)q-CH3, wherein each R is C1-C4 alkyl, wherein k, n, o, q are integers in the range of 0-8, provided that the total number of carbon atoms (including the carboxylate) is in the range of 10 to 18.

In each of the above formulas A, B and C, the species M can be any suitable, especially water-solubilizing, counterion.

Especially preferred secondary soap surfactants for use herein are watersoluble members selected from the group consisting of the water-soluble salts of 2-methyl-l -undecanoic acid, 2-ethyl-l-decanoic acid, 2-propyl- 1 - nonanoic acid, 2-butyl-l-octanoic acid and 2-pentyl-1-heptanoic acid.

Alkali metal sarcosinate surfactant Other suitable anionic surfactants are the alkali metal sarcosinates of formula R-CON (tri) CH2 COOM, wherein R is a C5-C17 linear or branched alkyl or alkenyl group, R1 is a C1-C4 alkyl group and M is an alkali metal ion. Preferred examples are the myristyl and oleyl methyl sarcosinates in the form of their sodium salts.

Nonionic surfactant Essentially any anionic surfactants useful for detersive purposes can be included in the compositions. Exemplary, non-limiting classes of useful nonionic surfactants are listed below.

Nonionic polvhvdroxv fatty acid amide surfactant Polyhydroxy fatty acid amides suitable for use herein are those having the structural formula R2CONR1Z wherein : R1 is H, C1-C4 hydrocarbyl, 2hydroxy ethyl, 2-hydroxy propyl, or a mixture thereof, preferable C1-C4 alkyl, more preferably C1 or C2 alkyl, most preferably C1 alkyl (i.e., methyl); and R2 is a Cs-C31 hydrocarbyl, preferably straight-chain Cs-C1g alkyl or alkenyl, more preferably straight-chain Cg-C 17 alkyl or alkenyl, most preferably straight-chain Cl l-Cl7 alkyl or alkenyl, or mixture thereof; and Z is a polyhydroxyhydrocarbyl having a linear hydrocarbyl chain with at least 3 hydroxyls directly connected to the chain, or an alkoxylated derivative (preferably ethoxylated or propoxylated) thereof. Z preferably will be derived from a reducing sugar in a reductive amination reaction; more preferably Z is a glycityl.

Nonionic condensates of alkvl phenols The polyethylene, polypropylene, and polybutylene oxide condensates of alkyl phenols are suitable for use herein. In general, the polyethylene oxide condensates are preferred. These compounds include the condensation products of alkyl phenols having an alkyl group containing from about 6 to about 18 carbon atoms in either a straight chain or branched chain configuration with the alkylene oxide.

Nonionic ethoxvlated alcohol surfactant The alkyl ethoxylate condensation products of aliphatic alcohols with from about 1 to about 25 moles of ethylene oxide are suitable for use herein. The alkyl chain of the aliphatic alcohol can either be straight or branched, primary or secondary, and generally contains from 6 to 22 carbon atoms.

Particularly preferred are the condensation products of alcohols having an alkyl group containing from 8 to 20 carbon atoms with from about 2 to about 10 moles of ethylene oxide per mole of alcohol.

Nonionic ethoxvlated/propoxvl chain length of from 10 to 18 carbon atoms, a degree of ethoxylation of from 3 to 30 and a degree of propoxylation of from 1 to 10.

Nonionic EO/PO condensates with propylene glycol The condensation products of ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol are suitable for use herein. The hydrophobic portion of these compounds preferably has a molecular weight of from about 1500 to about 1800 and exhibits water insolubility. Examples of compounds of this type include certain of the commercially-available PluronicTM surfactants, marketed by BASF.

Nonionic EO condensation products with propylene oxide/ethvlene di amine adducts The condensation products of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylenediamine are suitable for use herein. The hydrophobic moiety of these products consists of the reaction product of ethylenediamine and excess propylene oxide, and generally has a molecular weight of from about 2500 to about 3000.

Examples of this type of nonionic surfactant include certain of the commercially available TetronicTM compounds, marketed by BASF.

Nonionic alkvlpolvsaccharide surfactant Suitable alkylpolysaccharides for use herein are disclosed in U.S. Patent 4,565,647, Llenado, issued January 21, 1986, having a hydrophobic group containing from about 6 to about 30 carbon atoms, preferably from about 10 to about 16 carbon atoms and a polysaccharide, e.g., a polyglycoside, hydrophilic group containng from about 1.3 to about 10, preferably from about 1.3 to about 3, most preferably from about 1.3 to about 2.7 saccharide units. Any reducing saccharide containing 5 or 6 carbon atoms can be used, e.g., glucose, galactose and galactosyl moieties can be substituted for the glucosyl moieties. (Optionally the hydrophobic group is attached at the 2-, 3-, 4-, etc. positions thus giving a glucose or galactose as opposed to a glucoside or galactoside.) The intersaccharide bonds can be, e.g., between e.g., between the one position of the additional saccharide units and the 2-, 3-, 4-, and/or 6- positions on the preceding saccharide units.

The preferred alkylpolyglycosides have the formula R20(CnH2nO)t(glycosyl)x wherein R2 is selected from the group consisting of alkyl, alkyiphenyl, hydroxyalkyl, hydroxyalkylphenyl, and mixtures thereof in which the alkyl groups contain from 10 to 18, preferably from 12 to 14, carbon atoms; n is 2 or 3, preferably from about 1.3 to about 3, most preferably from about 1.3 to about 2.7. The glycosyl is preferably derived from glucose.

Nonionic fattv acid amide surfactant Fatty acid amide surfactants suitable for use herein are those having the formula:

wherein R6 is an alkyl group containing from 7 to 21, preferably from 9 to 17 carbon atoms and each R7 is selected from the group consisting of hydrogen, C1-C4 alkyl, C1-C4 hydroxyalkyl, and -(C2H40)XH, where x is in the range of from 1 to 3.

Amphoteric surfactant Suitable amphoteric surfactants for use herein include the amine oxide surfactants and the alkyl amphocarboxylic acids.

A suitable example of an alkyl aphodicarboxylic acid for use herein is Miranol(TM) C2M Conc. manufactured by Miranol, Inc., Dayton, NJ.

Amine Oxide surfactant Amine oxides useful in the present invention include those compounds having the formula:

wherein R3 is selected from an alkyl, hydroxyalkyl, acylamidopropoyl and alkyl phenyl group, or mixtures thereof, containing from 8 to 26 carbon atoms, preferably 8 to 18 carbon atoms; R4 is an alkylene or hydroxyalkylene group containing from 2 to 3 carbon atoms, preferably 2 carbon atoms, or mixtures thereof; x is from 0 to 5, preferably from 0 to 3; and each R5 is an alkyl or hydyroxyalkyl group containing from 1 to 3, preferably from 1 to 2 carbon atoms, or a polyethylene oxide group containing from 1 to 3, preferable 1, ethylene oxide groups. The R5 groups can be attached to each other, e.g., through an oxygen or nitrogen atom, to form a ring structure.

These amine oxide surfactants in particular include C 10-C18 alkyl dimethyl amine oxides and C8-C18 alkoxy ethyl dihydroxyethyl amine oxides.

Examples of such materials include dimethyloctylamine oxide, diethyldecylamine oxide, bis-(2-hydroxyethyl)dodecylamine oxide, dimethyldodecylamine oxide, dipropyltetradecylamine oxide, methylethylhexadecylamine oxide, dodecylamidopropyl dim ethyl amine oxide, cetyl dimethylamine oxide, stearyl dimethylamine oxide, tallow dimethylamine oxide and dimethyl-2-hydroxyoctadecylamine oxide.

Preferred are Clo-Cig alkyl dimethylamine oxide, and C10-l8 acylamido alkyl dimethylamine oxide.

Zwitterionic surfactant Zwitterionic surfactants can also be incorporated into the detergent compositions hereof. These surfactants can be broadly described as derivatives of secondary and tertiary amines, derivatives of heterocyclic secondary and tertiary amines, or derivatives of quatemary ammonium, quaternary phosphonium or tertiary sulfonium compounds. Betaine and sultaine surfactants are exemplary zwitterionic surfactants for use herein.

Betaine surfactant The betaines useful herein are those compounds having the formula R(R')2N+R2COO- wherein R is a C6-C 18 hydrocarbyl group, preferably a C10-Cl6 alkyl group or C10-l6 acylamido alkyl group, each R1 is typically C1-C3 alkyl, preferably methyl,m and R2 is a C1-C5 hydrocarbyl group, preferably a Ci -C3 alkylene group, more preferably a C1-C2 alkylene group. Examples of suitable betaines include coconut acylamidopropyldimethyl betaine; hexadecyl dimethyl betaine; C 12-14 acylamidopropylbetaine; C8 14 acylamidohexyldiethyl betaine; 4 [C 14-16 acylmethylamidodiethylammonio]- 1 -carboxybutane; C 16-18 acylamidodimethylbetaine; C 16 acylamidopentanediethyl-betaine; [C 1216 acylmethylamidodimethylbetaine. Preferred betaines are C1 2-18 dimethyl-ammonio hexanoate and the C 10-18 acylamidopropane (or ethane) dimethyl (or diethyl) betaines. Complex betaine surfactants are also suitable for use herein.

Sultaine surfactant The sultaines useful herein are those compounds having the formula (R(R1 )2N+R2SO3- wherein R is a C6-Cl 8 hydrocarbyl group, preferably a C10-C16 alkyl group, more preferably a C12-C13 alkyl group, each R1 is typically C 1-C3 alkyl, preferably methyl, and R2 is a C1 -C6 hydrocarbyl group, preferably a C1-C3 alkylene or, preferably, hydroxyalkylene group.

Ampholvtic surfactant Ampholytic surfactants can be incorporated into the detergent compositions herein. These surfactants can be broadly described as aliphatic derivatives of secondary or tertiary amines, or aliphatic derivatives of heterocyclic secondary and tertiary amines in which the aliphatic radical can be straight chain or branched.

Cationic surfactants Cationic surfactants can also be used in the compositions herein. Suitable cationic surfactants include the quaternary ammonium surfactants selected from mono C6-C16, preferably C6-Clo N-alkyl or alkenyl ammonium surfactants wherein the remaining N positions are substituted by methyl, hydroxyethyl or hydroxypropyl groups.

Lime soap dispersant compound The compositions of the invention may contain a lime soap dispersant compound, which has a lime soap dispersing power (LSDP), as defined hereinafter of no more than 8, preferably no more than 7, most preferably no more than 6. The lime soap dispersant compound is preferably present at a level of from 0. 1% to 40% by weight, more preferably 1% to 20% by weight, most preferably from 2% to 10% by weight of the compositions.

A lime soap dispersant is a material that prevents the precipitation of alkali metal, ammonium or amine salts of fatty acids by calcium or magnesium ions. A numerical measure of the effectiveness of a lime soap dispersant is given by the lime soap dispersing power (LSDP) which is determined using the lime soap dispersion test as described in an article by H.C. Borghetty and C.A. Bergman, J. Am. Oil. Chem. Soc., volume 27, pages 88-90, (1950). This lime soap dispersion test method is widely used by practitioners in this art field being referred to , for example, in the following review articles; W.N. Linfield, Surfactant Science Series, Volume 7, p3; W.N. Linfield, Tenside Surf. Det., Volume 27, pagesl59-161, (1990); and M.K. Nagarajan, W.F. Masler, Cosmetics and Toiletries, Volume 104, pages 71-73, (1989). The LSDP is the % weight ratio of dispersing agent to sodium oleate required to disperse the lime soap deposits formed by 0.025g of sodium oleate in 30ml of water of 333ppm CaC03 (Ca:Mg=3:2) equivalent hardness.

Polymeric lime soap dispersants suitable for use herein are described in the article by M.K. Nagarajan and W.F. Masler, to be found in Cosmetics and Toiletries, Volume 104, pages 71-73, (1989). Examples of such polymeric lime soap dispersants include certain water-soluble salts of copolymers of acrylic acid, methacrylic acid or mixtures thereof, and an acrylamide or substituted acrylamide, where such polymers typically have a molecular weight of from 5,000 to 20,000.

Surfactants having good lime soap dispersant capability will include certain amine oxides, betaines, sulfobetaines, alkyl ethoxysulfates and ethoxylated alcohols.

Exemplary surfactants having a LSDP of no more than 8 for use in accord with the invention include C16-C18 dimethyl amine oxide, C12-C18 alkyl ethoxysulfates with an average degree of ethoxylation of from 1-5, particularly C 12-Cl 5 alkyl ethoxysulfate surfactant with a degree of ethoxylation of about 3 (LSDP=4), and the C1 3-C 15 ethoxylated alcohols with an average degree of ethoxylation of either 12 (LSDP=6) or 30, sold under the trade names Lutensol A012 and Lutensol A030 respectively, by BASF GmbH.

Solvent The compositions of the invention may contain organic solvents, particularly when formulated as liquids or gels. The compositions in accord with the invention preferably contain a solvent system present at levels of from 1% to 30% by weight, preferably from 3% to 25% by weight, more preferably form 5% to 20% by weight of the composition. The solvent system may be a mono, or mixed solvent system. Preferably, at least the major component of the solvent system is of low volatility.

Suitable organic solvent for use herein has the general formula RO(CH2C(Me)HO)nH, wherein R is an alkyl, alkenyl, or alkyl aryl group having from 1 to 8 carbon atoms, and n is an integer from 1 to 4.

Preferably, R is an alkyl group containing 1 to 4 carbon atoms, and n is 1 or 2. Especially preferred R groups are n-butyl or isobutyl. Preferred solvents of this type are 1-n-butoxypropane-2-ol (n=l); and 1 (2-n-butoxy- 1 - methylethoxy)propane-2-ol (n=2), and mixtures thereof.

Other solvents useful herein include the water soluble CARBITOL solvents or water-soluble CELLOSOLVE solvents. Water-soluble CARBITOL solvents are compounds of the 2-(2 alkoxyethoxy)ethanol class wherein the alkoxy group is derived from ethyl, propyl or butyl; a preferred watersoluble carbitol is 2-(2-butoxyethoxy)ethanol also known as butyl carbitol.

Water-soluble CELLOSOLVE solvents are compounds of the 2alkoxyethoxy ethanol class, with 2-butoxyethoxyethanol being preferred.

Other suitable solvents are benzyl alcohol, and diols such as 2-ethyl-1,3hexanediol and 2,2,4-trimethl- 1 ,3-pentanediol.

The low molecular weight, water-soluble, liquid polyethylene glycols are also suitable solvents for use herein.

The alkane mono and diols, especially the C1-C6 alkane mono and diols are suitable for use herein. C1 -C4 monohydric alcohols (eg: ethanol, propanol, isopropanol, butanol and mixtures thereof) are preferred, with ethanol particularly preferred. The C1-C4 dihydric alcohols, including propylene glycol, are also preferred.

Hvdrotropes Hydrotrope may be added to the compositions in accord with the present invention, and is typically present at levels of from 0.5% to 20%, preferably from 1% to 10%, by weight.

Useful hydrotropes include sodium, potassium, and ammonium xylene sulfonates, sodium, potassium, and ammonium toluene sulfonate, sodium potassium and ammonium cumene sulfonate, and mixtures thereof.

Optional detergent components Whilst the rinse aid compositions of the invention preferably contain optional detergent components selected from a detergent builder system, a surfactant system, a solvent, a hydrotrope, a pH adjusting agent and an organic polymeric compound, as described herein, they preferably do not contain cleaning components more typically found in machine dishwashing detergent compositions, such as bleaching species and enzymes.

Form of the compositions The compositions of the invention can be formulated in any desirable form such as powders, granulates, pastes, liquids and gels. Liquid compositions are most preferred.

Liquid compositions The compositions of the present invention are preferably formulated as liquid compositions which typically comprise from 94% to 35% by weight, preferably from 90% to 40% by weight, most preferably from 80% to 50% by weight of a liquid carrier, e.g., water, preferably a mixture of water and organic solvent.

Gel compositions Gel compositions are typically formulated with polyakenyl polyether having a molecular weight of from about 750,000 to about 4,000,000.

Machine dishwashing method The rinse aid compositions in accord with the present invention may be used in essntially any conventional machine dishwashing method of the conventional type performed using a dishwasher machine, which may be selected from any of those commonly available on the market.

The machine dishwashing method typically comprises treating soiled articles, such as crockery, glassware, hollowware and cutlery, with an aqueous liquid having dissolved or dispersed therein an effective amount of detergent composition. By an effective amount of detergent composition it is generally meant from 8g to 60g of detergent composition per wash, dissolved or dispersed in a wash solution volume of from 3 to 10 litres, as are typical product dosages employed in conventional machine dishwashing methods. The wash temperature may be in the range 40OC to 650C as commonly is employed in such processes. The rinse aid composition is typically employed at levels of from 0.5g to 10g of rinse aid composition per rinse cycle.

EXAMPLES The following examples illustrate the present invention.

In the following compositions, the abbreviated identifications have the following meanings: Citric: Citric acid Nonionic: C13-C15 mixed ethoxylated/propoxylated fatty alcohol with an average degree of ethoxylation of 3.8 and an average degree of propoxylation of 4.5 sold under the tradename Plurafac LF404 by BASF Gmbh.

HEDP: Ethane l-hydroxy-1,1-diphosphonic acid DETPMP: Diethylene triamine penta (methylene phosphonic acid), marketed by Monsanto under the tradename Dequest 2060 EDDS: Ethylenediamine-N, N'-disuccinic acid [S,S] isomer MGDA: Methyl glycine do acetic acid AA/MA: Random copolymers of acrylic acid and methacrylic acid in a weight ratio of approximately 30:70, with a molecular weight of about 3,500 Polyacrylate: A polyacrylate homopolymer with an average molecular weight of 8,000 sold under the tradename PA30 by BASF GmbH SCS: Sodium cumene sulfonate MA/AA: Copolymers of 1:4 maleic/acrylic acid, average molecular weight about 80,000 Example 1 The following liquid rinse aid compositions were prepared in accord with the invention (parts by weight).

A B C D E F Citric 6.5 6.5 6.5 6.5 6.5 6.5 Nonionic 12.0 12.0 12.0 12.0 12.0 12.0 HEDP - 5.0 2.5 5.0 5.0 5.0 DETPMP - - 3.0 - EDDS - - - 3.0 MGDA 1.0 2.0 3.0 4.0 5.0 2.5 ATCA 2.00 2.00 2.00 2.00 2.00 Polyacrylate - - - - 5.0 MA/AA - - - - - 5.0 SCS 4.8 4.8 4.8 4.8 4.8 4.8 Ethanol 6.0 6.0 6.0 6.0 6.0 6.0 Ammonia 0.7 0.7 - 0.7 0.7 0.7 Water/misc to balance pH 1% 3.3 3.3 2.4 3.3 3.3 3.3 solution

Claims (11)

1. Claims 1. A rinse aid composition containing an amino tricarboxylic acid or its salts or complexes of general formula:

   where R1, R2 and R3 are alkyl groups or substituted alkyl groups of chain length C1 to C4; n isO or 1; and X is an organic substituent group.
2. 2. A rinse aid composition according to Claim 1 wherein said amino tricarboxylic acid component is present at a level of from 0.005% to 20% by weight of the composition.
3. 3. A rinse aid composition according to either of Claims 1 or 2 wherein said amino tricarboxylic acid component is methyl glycine diacetic acid present at a level of from 0.1 % to 15% by weight of the composition.
4. 4. A rinse aid composition according to any of Claims 1 - 3 wherein the pH of said composition as a 1% solution in distilled water is less than 7.
5. 5. A rinse aid composition according to any of Claims 1-4 containing an organic polymer containing acrylic acid or its salts, having an average molecular weight of less than 15,000.
6. 6. A rinse aid composition according to Claim 5 wherein said organic polymer is a homopolymer having a molecular weight of from 500 to 12,000.
7. 7. A rinse aid composition according to either of Claims 5 or 6 wherein said organic polymer is present at a level of from 0.005% to 20% by weight of the composition.
8. 8. A rinse aid composition according to any of Claims 1-7 containing from 0.005% to 20% by weight of a heavy metal ion sequestrant.
9. 9. A rinse aid composition according to any of Claims 1 - 8 containing from 0.5% to 60% by weight of a detergent builder system.
10. 10. A rinse aid composition according to any of Claims 1 - 9 containing from 0.5% to 40% by weight of a surfactant system.
11. 11. The use of a rinse aid composition according to any of Claims 1 10 in a machine rinsing method.