AQUEOUS RINSE-AID COMPOSITION

Abstract

 The present invention is directed to an aqueous rinse-aid composition comprising
a) a fatty alcohol ethoxylate propoxylate, b) a phosphoric acid ester of an alkoxylated fatty alcohol being a mixture of compounds according to formula (I)

wherein R¹ is each independently selected from residues of a linear fatty alcohol comprising at least 6 carbon atoms and residues of a branched fatty alcohol comprising at least 12 carbon atoms, A is -(C₂H₄O)_m-(C₃H₆O)_n- or -(C₃H₆O)_n-(C₂H₄O)_m-, wherein m has an average value of from 1 to 15 and n has an average value of from 1 to 7 or is 0, including a random distribution of -C₂H₄O-and -C₃H₆O- units, i = 1, 2 or 3, preferably 1 or 2, j = 0, 1 or 2, preferably 1 or 2, the sum of i + j = 3, or salts thereof, and c) a fatty alcohol ethoxylate. The rinse-aid composition is used in a automatic dishwasher in a method of cleaning kitchenware and tableware by adding the composition in the rinsing step.

Description

[0001] The present invention relates to an aqueous rinse-aid composition comprising a phosphoric ester of an alkoxylated fatty alcohol.

[0002] Hard surfaces that are washed but not dried often suffer from spotting. In particular, glassware, dishes, and cutlery washed in an automatic dishwasher may develop hard water spots. Such hard water spots are undesirable because they have an undesirable appearance causing the clean objects to appear dirty. To overcome this problem, rinse aids are often used to minimize or hopefully eliminate such spotting. The formation of films on the dishware surfaces is also undesirable. Conventional rinse-aids comprise nonionic surfactants and organic acids such as citric acid or lactic acid.

[0003] There is a continuing need to improve the properties of all dishware surfaces in automatic dishwashers, including but not limited to glass, plastic, metal, and ceramic surfaces. The object of the present invention is to provide a new rinse-aid composition which results in dishware surfaces of different types having excellent anti-spotting and anti-filming properties.

[0004] The object is solved by an aqueous rinse-aid composition comprising:

a) a fatty alcohol ethoxylate propoxylate,

b) a phosphoric acid ester of an alkoxylated fatty alcohol being a mixture of compounds according to formula (I)

wherein

R¹ is each independently selected from residues of a linear fatty alcohol comprising at least 6 carbon atoms and residues of a branched fatty alcohol comprising at least 12 carbon atoms,

A is -(C₂H₄O)_m-(C₃H₆O)_n- Or -(C₃H₆O)_n-(C₂H₄O)_m-, wherein m has an average value of from 1 to 15 and n has an average value of from 1 to 7 or preferably is 0, including a random distribution of -C₂H₄O- and -C₃H₆O- units,

i = 1, 2 or 3, preferably 1 or 2,

j = 0, 1 or 2, preferably 1 or 2,

the sum of i + j = 3,

or salts thereof, and

c) a fatty alcohol ethoxylate.

[0005] The present invention also concerns the use of the composition as a rinse aid in an automatic dishwasher. The present invention further relates to a method of cleaning kitchenware and tableware in an automatic dishwasher comprising adding the rinse-aid composition in the rinsing step. The present invention is also directed to a method for preparing the rinse-aid composition comprising mixing the fatty alcohol ethoxylate propoxylate (a), the phosphoric acid ester (b), fatty alcohol ethoxylate (c) and water in any sequence.

[0006] Typically, the inventive rinse-aid composition comprises fatty alcohol ethoxylate propoxylate (a) and phosphoric acid ester (b) in a weight ratio of (a) to (b) which is less than 24:1, preferably less than 20:1, more preferably less than 15:1. In certain embodiments the weight ratio of fatty alcohol ethoxylate propoxylate (a) to phosphoric acid ester (b) is in the range from 10:1 to 1:1, preferably from 6:1 to 1:1, more preferably from 5:1 to 1:1, and most preferably from 4:1 to 1:1 such as 4:1 to 2:1 or about 3:1. The weight ratio of phosphoric acid ester (b) to fatty alcohol ethoxylate (c) is typically in the range from 6:1 to 1:4, preferably from 4:1 to 1:2, more preferably from 3:1 to 1:1, and most preferably about 2:1.

[0007] The rinse-aid composition of the present invention is an aqueous system comprising water which is typically the major component. In certain embodiments the rinse-aid composition comprises at least 78 % by weight, preferably at least 80 % by weight, and more preferably at least 85 % by weight of water, based on the total weight of the composition.

[0008] The total amount of fatty alcohol ethoxylate propoxylate (a), phosphoric acid ester (b), and fatty alcohol ethoxylate (c) typically makes up less than 22 % by weight, preferably less than 20 % by weight, and more preferably less than 15 % by weight of the total weight of the rinse-aid composition.

[0009] In a typical embodiment the rinse-aid composition comprise 1 to 11 % by weight, preferably 3 to 9 % by weight of fatty alcohol ethoxylate propoxylate (a), 0.5 to 5 % by weight, preferably 0.8 to 3.5 % by weight of phosphoric acid ester (b), > 0 to 3 % by weight, preferably 0.2 to 2 % by weight of fatty alcohol ethoxylate (c), and water in an amount adding up to 100 % by weight, each based on the total weight of the composition.

Fatty alcohol ethoxylate propoxylate (a)

[0010] The fatty alcohol ethoxylate propoxylate (a) for use in the present rinse-aid composition is preferably not end-capped with a methyl group, more preferably it is not end-capped with any alkyl group. Generally, the fatty alcohol ethoxylate propoxylate (a) is a mixture of compounds according to formula (II)

         R³-O-B-R⁴     (II),

wherein R³ is a residue of a fatty alcohol, R⁴ is selected from H and C₁ to C₅ alkyl, preferably R⁴ is H, B is -(C₂H₄O)_x-(C₃H₆O)_y- or -(C₃H₆O)_y-(C₂H₄O)_x-, wherein x has an average value of from 1 to 16 and y has an average value of from 1 to 16, including a random distribution of -C₂H₄O- and -C₃H₆O- units.

[0011] R³ can be the residue of a saturated, mono-, di- or polyunsaturated fatty acid; preferably it is the residue of a saturated fatty acid. More preferably R³ is selected from C₈ to C₂₂ alkyl, such as C₁₀ to C₂₀ alkyl, more preferably C₁₀ to C₁₈ alkyl, and most preferably C₁₂ to C₁₆ alkyl, such as C₁₂ to C₁₄ alkyl. R³ comprises an even or uneven number of carbon atoms with an even number of carbon atoms being preferred. R³ comprises a linear or branched carbon chain with a linear carbon chain being preferred. In a preferred embodiment R³ is C₁₂ alkyl and/or C₁₄ alkyl, typically the fatty alcohol ethoxylate propoxylate (a) is a mixture of compounds of formula (II) wherein R³ is C₁₂ alkyl and compounds of formula (II) wherein R³ is C₁₄ alkyl.

[0012] Usually, R³ is derived from naturally occurring fatty acids such as the fatty acids of the triglycerides present in vegetable or animal fats. Preferred base materials from which R³ can be derived are coconut and/or palm kernel oil both containing high amounts of lauric and myristic acid.

[0013] In formula (II) B represents the mixed poly(ethylene glycol) / poly(propylene glycol) units of the alcohol ethoxylate propoxylate (a) with x being the number of ethylene oxide (EO) units and y being the number of propylene oxide (PO) units. In typical embodiments x has an average value of from 2 to 15, preferably from 2 to 12, more preferably from 3 to 10, and most preferably from 4 to 8; and y has an average value of from 2 to 15, preferably from 2 to 12, more preferably from 3 to 10, and most preferably from 3 to 7, such as x having an average value of from 4 to 6, preferably about 5, and y having an average value of from 3 to 5, preferably about 4. In some embodiments x is larger than y. Typically, the sum of x and y is in the range from 2 to 20, preferably from 4 to 14, more preferably from 7 to 11, and most preferably about 9.

[0014] In preferred embodiments the fatty alcohol ethoxylate propoxylate (a) has an average HLB value in the range from 4 to 11, preferably from 5 to 10, more preferably from 6 to 9, even more preferably from 6 to 8, and most preferably of about 7.

[0015] The hydrophilic-lipophilic balance (HLB) values referred to within this application are calculated according to the following formula

wherein Mh is the molecular mass (sum of atomic masses) of the hydrophilic portion of the molecule, and M is the molecular mass of the whole molecule. The calculated HLB values range from 0 to 20. An HLB value of 0 corresponds to a completely lipophilic (hydrophobic) molecule, and a value of 20 corresponds to a completely hydrophilic (lipophobic) molecule. Ethylene oxide units, hydroxyl groups, and P=O (in the phosphoric acid ester) are hydrophilic. Propylene oxide units are not considered part of the hydrophilic portion of the molecule.

[0016] The fatty alcohol ethoxylate propoxylate (a) is a nonionic surfactant and typical nonionic surfactants suitable as component (a) for use in the present invention are commercially available nonionic surfactants, e.g. Dehypon^® LS 24, LS 36, LS 45 and LS 54 and Dehypon^® LF 301, LF 303, LF 400, LF 404 and LS 531, all available from BASF, with Dehypon^® LS 54 being preferred.

Phosphoric acid ester (b)

[0017] The phosphoric acid ester (b) for use in the present rinse-aid composition is typically a mixture of monoesters (Ia) and diesters (Ib)

R¹ can be the residue of a saturated, mono-, di- or polyunsaturated fatty acid; preferably it is the residue of a saturated fatty acid.

[0018] In formulas (I), (Ia), and (Ib) A represents the mixed poly(ethylene glycol) / poly(propylene glycol) units of the phosphoric acid ester (b) with m being the number of ethylene oxide (EO) units and n being the number of propylene oxide (PO) units. Preferably, n = 0 meaning that A only comprises EO units.

[0019] In embodiments wherein R¹ comprises a linear carbon chain it is preferably selected from C₆ to C₂₀ alkyl, more preferably C₆ to C₁₆ alkyl, even more preferably C₈ to C₁₄ alkyl, and most preferably C₈ to C₁₂ alkyl. An even number of carbon atoms is preferred. Usually, R¹ is derived from naturally occurring fatty acids such as the fatty acids of the triglycerides present in vegetable or animal fats.

[0020] For R¹ comprising a linear carbon chain the molar ratio of monoester (Ia) to diester (Ib) is typically in the range from 1:1 to 4:1, preferably from 1.5:1 to 3.5:1, more preferably from 1.8:1 to 3.2:1, and most preferably from 2:1 to 3:1 such as from 2.3:1 to 2.9:1 or about 2.6:1.

[0021] In a preferred embodiment R¹ is C₈ alkyl and/or C₁₀ alkyl, especially linear C₈ alkyl and/or C₁₀ alkyl. In this case the phosphoric ester (b) is typically a mixture of compounds of formula (I), preferably (Ia) and (Ib), wherein R¹ is C₈ alkyl and compounds of formula (I), preferably (Ia) and (Ib), wherein R¹ is C₁₀ alkyl. The molar ratio of C₈ alkyl to C₁₀ alkyl in the mixture of compounds of formula (I) is preferably in the range of from 40:60 to 60:40, and more preferably from 45:55 to 53:47.

[0022] For R¹ comprising a linear carbon chain A is preferably -(C₂H₄O)_m- and m typically has an average value of from 2 to 15, preferably from 2 to 12, more preferably from 3 to 10, and most preferably from 4 to 8, such as from 4 to 6, preferably about 5.

[0023] In other embodiments R¹ is the residue of a branched fatty alcohol comprising at least 12 carbon atoms. The branched fatty alcohols are typically mono-methyl-branched including iso-methyl-branched and anteiso-methyl-branched fatty alcohols. iso-Methyl-branched fatty alcohols have the branch point on the penultimate carbon (one from the end) and are preferred, while anteiso-methyl-branched fatty alcohols have the branch point on the ante-penultimate carbon (two from the end). R¹ can be the residue of an isoalkyl alcohol. Preferably, R¹ is selected from C₁₂ to C₂₂ isoalkyl, more preferably C₁₂ to C₂₀ isoalkyl, even more preferably C₁₂ to C₁₈ isoalkyl, and most preferably C₁₂ to C₁₆ isoalkyl such as C₁₃ isoalkyl. R¹ can comprise an even or preferably an uneven number of carbon atoms.

[0024] For R¹ comprising a branched carbon chain the molar ratio of monoester (Ia) to diester (Ib) is typically in the range from 3:1 to 1:3, preferably from 2:1 to 1:2 such as from 1.5:1 to 1:1.5 or about 1:1.

[0025] For R¹ comprising a branched carbon chain A is preferably -(C₂H₄O)_m- and m has an average value of from 4 to 15, preferably from 5 to 13, more preferably from 6 to 12, and most preferably from 7 to 11, such as from 8 to 10, preferably about 9.

[0026] Typically, the phosphoric acid ester (b) has an average HLB value in the range from 12.5 to 15.5, preferably from 13 to 15, more preferably from 13.5 to 14.5, even more preferably from 13.7 to 14.2, and most preferably of around 14.

[0027] The phosphoric acid ester (b) is an anionic surfactant. It can be prepared by reacting the respective alkoxylated fatty alcohols and either P₂O₅ (resulting in mainly mono- and diesters) or polyphosphoric acid (resulting in mainly monoesters) depending on the desired mono-/diester ratio. Typical anionic surfactants suitable as component (b) for use in the present invention are commercially available.

Fatty alcohol ethoxylate (c)

[0028] The fatty alcohol ethoxylate (c) for use in the present rinse-aid composition is preferably not end-capped. Generally, the fatty alcohol ethoxylate (c) is a mixture of compounds according to formula (III)

         R⁵-O-E-R⁶     (III),

wherein R⁵ is a residue of a fatty alcohol, R⁶ is selected from H and C₁ to C₅ alkyl, preferably R⁶ is H, E is -(C₂H₄O)_z-, wherein z has an average value of from 1 to 22.

[0029] Typically, R⁵ comprises from 8 to 30 carbon atoms, preferably from 10 to 26 carbon atoms, more preferably from 12 to 22 carbon atoms, and most preferably from 14 to 20 carbon atoms. R⁵ comprises an even or uneven number of carbon atoms with an even number of carbon atoms being preferred. R⁵ comprises a linear or branched carbon chain with a linear carbon chain being preferred. R⁵ can be the residue of saturated, mono-, di- or polyunsaturated fatty alcohol. Preferably, R⁵ is selected from mono-, di- and polyunsaturated fatty alcohol residues, more preferably from monounsaturated fatty alcohol residues. Often the double bond is located between the 9^th an 10^th carbon atom starting from the carbon atom bound to the hydroxyl group.

[0030] In preferred embodiments R⁵ is C₁₆ alkenyl, typically monounsaturated, and/or C₁₈ alkenyl, typically monounsaturated. More preferably, the fatty alcohol ethoxylate (c) is a mixture of compounds (III) wherein R⁵ is the residue of palmitoleyl alcohol (16:1 = cis-9-hexadecen-1-ol) and compounds (III) wherein R⁵ is the residue of oleyl alcohol (18:1 = cis-9-octadecen-1-ol).

[0031] Usually, R⁵ is derived from naturally occurring fatty acids such as the fatty acids of the triglycerides present in vegetable or animal fats or from a petrochemical source.

[0032] In formula (III) E represents the poly(ethylene glycol) units of the fatty alcohol ethoxylate (c) with z being the number of ethylene oxide (EO) units. In typical embodiments z has an average value of from 2 to 20, preferably from 3 to 18, more preferably from 4 to 16, and most preferably from 5 to 14, such as from 6 to 12, preferably from 7 to 11, more preferably from 8 to 10, and most preferably about 9.

[0033] Typically, the fatty alcohol ethoxylate (c) has an average HLB value in the range from 11 to 14.5, preferably from 11.2 to 14, more preferably from 11.5 to 13.8, even more preferably from 11.8 to 13.5, still more preferably from 12 to 13.2, still more preferably from 12.5 to 13, and most preferably of about 12.7.

[0034] The fatty alcohol ethoxylate (c) is a nonionic surfactant and typical nonionic surfactants suitable as component (c) for use in the present invention are commercially available nonionic surfactants, e.g. Emulan^® AT9, Emulan^® AF, Dehypon^® E124-90, Dehypon^® E 127, Dehypon^® GRA, Dehypon^® KE 3447, Dehypon WET, Lutensol^® AT 80, Lutensol^® AT 25, Lutensol^® AT 50, all available from BASF, and Genapol^® EC 50, available from Clariant, with Emulan^® AT9 being preferred.

Optional components

[0035] The rinse-aid composition of the present invention can comprise impurities introduced with the phosphoric ester (b) which impurities originate from its production process. These impurities can comprise at least one of a fatty alcohol R¹-OH, an alkoxylated fatty alcohol R¹-O-A-H, and phosphoric acid. They may be present each in an amount of less than 0.5 % by weight, typically less than 0.3 % by weight, each based on the total weight of the composition. Of, course further impurities dragged in by other components of the rinse-aid composition such as the fatty alcohol ethoxylate propoxylate (a) and the fatty alcohol ethoxylate (c) may be present.

[0036] The rinse-aid composition can comprise citric acid, although it is preferably free of citric acid, more preferably free of any organic acid. If citric acid is present, the weight ratio of citric acid to phosphoric acid ester (b) is typically in the range from 3:1 to 1:3, preferably from 2:1 to 1:2, more preferably from 1.5:1 to 1:1.5, and most preferably about 1:1.

[0037] Typically, the rinse-aid composition of the present invention does not contain sodium cumenesulfonate in an amount of more than 4 % by weight, preferably 0.5 % by weight, based on the total weight of the composition. More preferably the rinse-aid composition is free of sodium cumenesulfonate, and most preferably free of cumenesulfonic acid and any of its salts.

[0038] Preferably, the rinse-aid composition is free of any cationic surfactant and/or amphoteric surfactant.

[0039] In certain embodiments the present rinse-aid composition does not contain any further anionic surfactant in addition to the phosphoric acid ester (b) in amounts of more than 1 % by weight, preferably more than 0.5 % by weight, based on the total weight of the composition, and more preferably is free of any further anionic surfactant.

[0040] Typically, the rinse-aid composition does not contain any further nonionic surfactant in addition to fatty alcohol ethoxylate propoxylate (a), fatty alcohol ethoxylate (c) and impurities introduced with phosphoric acid ester (b) in amounts of more than 1 % by weight, preferably more than 0.5 % by weight, based on the total weight of the composition, and more preferably is free of any further nonionic surfactant.

[0041] The rinse-aid composition may contain further optional ingredients selected from colorants, fragrances, odor absorbers, glass corrosion inhibitors, preservatives/antibacterial agents, neutralizing agents, rheology modifiers, aversive agents, foam controlling agents, enzymes, and mixtures thereof.

[0042] Colorants can be used for improving the attractiveness of the rinse aid to users of the product. They can also be used for masking undesired colors caused by the ingredients of the composition. Appropriate colorants are any colorants suited for use in dishwashing applications which are typically organic dyes. They are commonly known and commercially available, for example from Clariant and BASF, such as Nylosan yellow N-7GL, Sanolin brilliant flavine 8GZ, Sanolin yellow BG, Vitasyn quinoline yellow 70, Vitasyn tartrazine X90, Puricolor yellow AYE23, Basacid yellow 232, Vibracolor yellow AYE17, Puricolor red ARE27, Puricolor red ARE14, Vibracolor red ARE18, Vibracolor red ARE52, Vibracolor red SRE3, Basacid red 316, Ponceau SX, Iragon blue DBL86, Sanolin blue EHRL, Sanolin turquoise blue FBL, Basacid blue 750, Iragon blue ABL80, Vitasyn blue AE90, Basacid blue755, Vitasyn patentblue V 8501 and Vibracolor green AGR25. One or more colorants can be present in the rinse-aid composition in a total amount of from 0.0001 to 0.1 % by weight, based on the total weight of the rinse-aid composition.

[0043] Fragrances can be used for improving the attractiveness of the rinse aid to users of the product. It can be used for masking undesired malodors caused by the ingredients of the composition or the dishwasher detergent or the dishwasher or the soils that were/are present in the dishwasher or combinations of these. After the washing in the dishwasher has been completed the rinse aid perfume is responsible for a pleasant smell inside the dishwasher and/or the immediate surrounding of the dishwasher. Odor absorbers have the capability of capturing malodor molecules and thus preventing an undesirable smell. Examples include cyclodextrin and cyclodextrine derivatives. One or more fragrances and/or odor absorbers can be present in the rinse-aid composition in a total amount of from 0.005 to 0.5 % by weight, based on the total weight of the rinse-aid composition.

[0044] Examples of glass corrosion inhibitors include zinc salts, such as zinc oxide, zinc chloride, zinc hydroxide, zinc sulfate, zinc citrate, and zinc phosphate; bismuth salts , such as bismuth subsalicylate, bismuth subcitrate, bismuth citrate, bismuth nitrate, bismuth chloride, bismuth oxide, and bismuth phosphate. One or more glass corrosion inhibitors can be present in the rinse-aid composition in a total amount of from 0.1 to 3 % by weight, based on the total weight of the rinse-aid composition.

[0045] Examples of preservatives/antibacterial agents include benzisothiazolinone, bronopol, chloromethylisothiazolinone, dichlorobenzylalcohol, formic acid, glutaraldehyde, iodopropynyl butylcarbamate, methylisothiazolinone, phenoxyethanol, and phenoxypropanol. One or more preservatives/antibacterial agents can be present in the rinse-aid composition in a total amount of from 0.0005 to 0.15 % by weight, based on the total weight of the rinse-aid composition.

[0046] Examples of neutralizing agents include alkaline agents such as potassium hydroxide, sodium hydroxide, potassium citrate, and sodium citrate. One or more neutralizing agents can be present in the rinse-aid composition in a total amount of from 0.05 to 1 % by weight, based on the total weight of the rinse-aid composition.

[0047] Examples of rheology modifiers include Arabic gum, arabinoxylan, guar gum, locust bean gum, pectin, starch, starch derivates, dextrin, tara gum, agar, alginate, carrageenan, acrylic based polymers, cross-linked acrylic based polymers, cellulose gums, cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, curdlan gum, diutan gum, gellan gum, and xantan gum. One or more rheology modifiers can be present in the rinse-aid composition in a total amount of from 0.1 to 1.5 % by weight, based on the total weight of the rinse-aid composition.

[0048] Examples of aversive agents include bitterants such as denatonium (e.g. denatonium benzoate and denatonium saccharide), sucrose octaacetate, quercetin, brucine, and quassin. One or more aversive agents can be present in the rinse-aid composition in a total amount of from 3 to 200 ppm by weight, based on the total weight of the rinse-aid composition.

[0049] Examples of foam controlling agents include polydimethylsiloxanes and other silicones, EO/PO based defoamers, stearates, and glycols. One or more foam controlling agents can be present in the rinse-aid composition in a total amount of from 0.001 to 0.2 % by weight, based on the total weight of the rinse-aid composition.

[0050] Examples of enzymes include lipase, cellulase, such as endocellulase, exocellulase, and cellulose phosphorylase. One or more enzymes can be present in the rinse-aid composition in a total amount of from 0.0005 to 0.1 % by weight, based on the total weight of the rinse-aid composition.

[0051] The pH of the inventive rinse-aid composition is typically within the range of from 1.8 to < 7, preferably from 2 to 5, more preferably from 2 to 4, even more preferably from 2.2 to 3, and most preferably of about 2.5.

[0052] The rinse-aid composition of the present invention can be prepared by mixing the fatty alcohol ethoxylate propoxylate (a), the phosphoric acid ester (b), fatty alcohol ethoxylate (c), optional components, and water in any sequence. Typically, components (a) to (c) and optional components are added to the water. At room temperature (about 23°C) components (a) and (c) may be present in a liquid or a solid waxy form depending on their molecular structure. Waxy components may require heating above their melting point in order to facilitate incorporation into the aqueous system. Often, the alcohol ethoxylate propoxylate (a) is in the liquid state at room temperature whereas the fatty alcohol ethoxylate (c) is often in a solid waxy state. Accordingly, the fatty alcohol ethoxylate (c) is typically heated before mixing in, preferably up to about 30°C or about 40°C or about 50°C or about 60°C or about 70°C or about 80°C.

[0053] In order to provide the rinse-aid composition with a pH of < 7, the phosphoric acid ester (b) is generally added in its acidic form rather than as a salt. If necessary, the pH value of the rinse-aid composition can be adapted by adding an alkaline agent such as those described above, e.g. potassium hydroxide and sodium hydroxide.

[0054] Generally, the rinse-aid composition of the present invention has a clear or slightly opaque appearance. The composition is mainly colorless or might have a slight brownish of yellowish color caused by the used components. Although the components of the rinse-aid composition are mostly dissolved in the aqueous system, a complete dissolution of all components is not mandatory and some opacity - sometimes resulting from surfactants (a) and/or (b) and/or (c) - does not impede the performance of the rinse-aid composition.

[0055] The rinse-aid composition is used as a rinse-aid in an automatic dishwasher including applications in private households as well as in institutional cleaning. When cleaning kitchenware and tableware in an automatic dishwasher the rinse-aid composition is added in the rinsing step. Usually, the rinse-aid composition is filled into a dedicated reservoir of the automatic dishwasher before starting the cleaning program. The dishwasher then automatically doses the rinse-aid composition to the cleaning process at the right time.

[0056] Objects which have been cleaned in an automatic dishwasher using the inventive rinse-aid composition exhibit excellent anti-spotting and anti-filming properties. These good cleaning results are achieved with different kinds of dishware, tableware, and kitchenware having different types of surfaces such as glass; ceramic (incl. china); plastic, e.g. melamine, PC, SAN; and metal, e.g. steel such as stainless steel. None of the materials is damaged by the inventive rinse-aid composition.

[0057] The present invention is illustrated by the following examples.

EXAMPLES

[0058] 

Description of rinse-test

[0059] The dishwashing machine used in the test was a Miele GSL. The program used was 50° with R-Zeit 2 (8 min).

[0060] The dishwasher had been loaded with the following items of which some were ballast load and some were evaluated for determining the performance:

3x Tupperware salad bowl, 600 ml,

2x IKEA plastic plates, KALAS, 900.969.08 / 13643,

3x Rosti Mepal, basic: melamine lunch plate p220 - ocean,

2x WACA, SAN plate, blue, Ø 24cm,

1 x Schott Zwiesel, cognac glass,

2x Schott Zwiesel, Paris beer glass, 275 ml, form 4858-42,

2x Cola glass, stackable, 22 cl,

2x Arcoroc, whisky glass Islande, 20 cl,

1x Schott Zwiesel, Mondial water glass, 323 ml, form 7500,

7x Bauscher, black china, plate flat with rim, 1030/20,

4x WMF, dessert knife, Berlin, 11 3806 6099,

1x WMF, dessert knife, Solid, SKU: 12.7906.6049,

4x stainless steel plate, 200 x 40 x 1 mm,

1x IKEA frying pan, Kavalkad, 24 cm diameter, article number 002.677.06.

[0061] The water used for this test was tap-water from Heerde, the Netherlands, that had been hardened up to a level of 9° German hardness, by adding aqueous solutions of calcium chloride, magnesium sulfate and sodium bicarbonate. The used water contained calcium and magnesium ions in a ratio of roughly 3 : 1 and between 2 and 3 mmol/l of HCO₃^-.

[0062] 90 g of frozen ballast soil in a glass jar were placed upside-down in the dishwasher at the moment it was turned on. The ballast soil had a temperature -25 to -15°C at the moment it was placed in the dishwasher. The ballast soil had the following composition:

150 weight parts of margarine

200 weight parts of egg yolk

400 weight parts of egg white

150 weight parts of potato starch

60 weight parts of cooking salt (sodium chloride)

3400 weight parts of water

[0063] Detergent ADD1 was dosed into the dosing chamber of the dishwasher in an amount of 20 g. ADD1 is an IEC Standard Dishwash Detergent Type B with the following composition:

30.0 weight %	sodium citrate dihydrate
6 weight %	maleic acid / acrylic acid copolymer sodium salt
5.0 weight %	sodium perborate monohydrate
2,0 weight %	TAED
25.0 weight %	sodium silicate (non-crystalline)
2.0 weight %	linear fatty alcohol ethoxylate
40 KNPU/kg	protease Savinase X.0T
300 KNU/kg	amylase Termamyl xxT
balance	sodium carbonate, anhydrous

[0064] The rinse-aid was dosed manually by opening the dishwasher door at the moment it would dose the rinse-aid automatically. 3.0 g of rinse-aid were dosed by placing a small beaker containing said rinse aid upside-down in the dishwasher.

[0065] During a rinse-aid performance test cycle identical dishwashers were operated simultaneously under the same conditions as described above. On day 1 they were run 3 times with no judgment of the load to generate stable washing conditions. On days 2 to 4 they were run once per day with subsequent judgment of the load each time. A selection of the total load of the dishwasher was judged manually on spots and filming. The judged items were the glasses Mondial, Paris, Islande and cola, two Tupperware bowls, a Rosti Mepal plate, a black china plate, a Berlin and a Solid knife. These items are grouped in the categories glass, plastic, ceramic and steel. The values indicated in the tables are the average values of the judgments on days 2 to 4.

[0066] The number of spots, the intensity of the spots and the intensity of the filming on the items in the dishwasher were judged manually according to the scale below.

10 = no spots / no filming

9 = very low intensity or number of spots / intensity of filming

8 = intermediate score

7 = low intensity or number of spots / intensity of filming

6 = intermediate score

5 = medium intensity or number of spots / intensity of filming

4 = intermediate score

3 = high intensity or number of spots / intensity of filming

2 = intermediate score

1 = very high intensity or number of spots / intensity of filming

[0067] The score on spots was the average of the score that was obtained in view of the intensity of the spots and the number of spots found on the judged items.

Table 2: Results on spotting (rinse-aid performance test cycle 1)

Example #	Glasses	Plastics	Ceramics	Steel	Average
E1	7.5	7.5	7.8	8.0	7.7
CE3	6.0	7.3	6.2	8.0	6.9
CE4	4.0	6.9	5.2	8.0	6.0
CE5	7.3	6.5	8.0	8.0	7.5
CE6	7.2	7.1	8.0	8.0	7.6
CE7	6.8	7.0	7.4	8.0	7.3

Table 3: Results on filming (rinse-aid performance test cycle 1)

Example #	Glasses	Plastics	Ceramics	Steel	Average
E1	4.6	6.5	4.8	6.0	5.5
CE3	4.3	6.1	4.4	3.3	4.5
CE4	5.3	6.3	5.8	4.6	5.5
CE5	4.4	6.0	2.8	4.0	4.3
CE6	3.9	6.0	3.8	5.6	4.8
CE7	4.1	6.2	4.6	4.0	4.7

Table 4: Results on spotting (rinse-aid performance test cycle 2)

Example #	Glasses	Plastics	Ceramics	Steel	Average
E1	7.5	7.8	7.8	7.8	7.7
E2	7.8	5.4	7.8	7.8	7.2
CE3	3.6	5.4	3.9	7.8	5.2
CE8	7.5	7.2	6.9	7.8	7.4

Table 5: Results on filming (rinse-aid performance test cycle 2)

Example #	Glasses	Plastics	Ceramics	Steel	Average
E1	5.3	7.4	3.5	5.3	5.4
E2	6.2	7.4	4.4	5.3	5.8
CE3	2.3	6.8	3.5	1.4	3.5
CE8	4.7	7.4	4.4	3.5	5.0

[0068] Comparing the performance of comparative rinse-aid compositions CE3 to CE8 with that of rinse-aid compositions E1 and E2 it is evident that inventive examples E1 and E2 have the best average performance on spotting as well as on filming. When the combined performance of spotting and filming is compared, E1 and E2 have a superior average performance compared to CE3 to CE8.

[0069] With respect to rinse-aid composition CE8 comprising the non-alkoxylated phosphoric acid ester it is noted that the plastic materials were slightly corroded.

[0070] The aspects of the invention are:

1. An aqueous rinse-aid composition comprising:

a) a fatty alcohol ethoxylate propoxylate,

b) a phosphoric acid ester of an alkoxylated fatty alcohol being a mixture of compounds according to formula (I)

wherein

R¹ is each independently selected from residues of a linear fatty alcohol comprising at least 6 carbon atoms and residues of a branched fatty alcohol comprising at least 12 carbon atoms,

A is -(C₂H₄O)_m-(C₃H₆O)_n- Or -(C₃H₆O)_n-(C₂H₄O)_m-,
wherein m has an average value of from 1 to 15 and n has an average value of from 1 to 7 or is 0, including a random distribution of -C₂H₄O- and -C₃H₆O- units,

i = 1, 2 or 3, preferably 1 or 2,

j = 0, 1 or 2, preferably 1 or 2,

the sum of i + j = 3,

or salts thereof, and

c) a fatty alcohol ethoxylate.

2. The rinse-aid composition of aspect 1 having a pH value within the range of from 1.8 to < 7, preferably from 2 to 5, more preferably from 2 to 4, even more preferably from 2.2 to 3, and most preferably of about 2.5.

3. The rinse-aid composition of any of aspects 1 or 2, wherein the weight ratio of fatty alcohol ethoxylate propoxylate (a) to phosphoric acid ester (b) is less than 24:1, preferably less than 20:1, more preferably less than 15:1.

4. The rinse-aid composition of any of aspects 1 to 3, wherein the weight ratio of fatty alcohol ethoxylate propoxylate (a) to phosphoric acid ester (b) is in the range from 10:1 to 1:1.

5. The rinse-aid composition of aspect 4, wherein the weight ratio of fatty alcohol ethoxylate propoxylate (a) to phosphoric acid ester (b) is in the range from 6:1 to 1:1, preferably from 5:1 to 1:1, and more preferably from 4:1 to 1:1.

6. The rinse-aid composition of any of aspects 1 to 5, wherein the weight ratio of phosphoric acid ester (b) to the fatty alcohol ethoxylate (c) is in the range from 6:1 to 1:4.

7. The rinse-aid composition of aspect 6, wherein the weight ratio of phosphoric acid ester (b) to the fatty alcohol ethoxylate (c) is in the range from 4:1 to 1:2, preferably from 3:1 to 1:1, and more preferably about 2:1.

8. The rinse-aid composition of any of aspects 1 to 7 comprising at least 50 % by weight of water, based on the total weight of the composition.

9. The rinse-aid composition of aspect 8 comprising at least 78 % by weight, preferably at least 80 % by weight, and more preferably at least 85 % by weight of water, based on the total weight of the composition.

10. The rinse-aid composition of any of aspects 1 to 9, wherein the total amount of components (a), (b), and (c) is less than 22 % by weight, preferably less than 20 % by weight, and more preferably less than 15 % by weight, based on the total weight of the composition.

11. The rinse-aid composition of any of aspects 1 to 10, further comprising as impurities introduced with the phosphoric ester (b) at least one of a fatty alcohol R¹-OH, an alkoxylated fatty alcohol R¹-O-A-H, and phosphoric acid, each in an amount of less than 0.5 % by weight, typically less than 0.3 % by weight, each based on the total weight of the composition.

12. The rinse-aid composition of any of aspects 1 to 11, further comprising citric acid.

13. The rinse-aid composition of aspect 12, wherein the weight ratio of citric acid to phosphoric acid ester (b) is in the range from 3:1 to 1:3, preferably from 2:1 to 1:2, more preferably from 1.5:1 to 1:1.5, and most preferably about 1:1.

14. The rinse-aid composition of any of aspects 1 to 11, which is free of citric acid, preferably free of any organic acid.

15. The rinse-aid composition of any of aspects 1 to 14, which does not contain sodium cumenesulfonate in an amount of more than 4 % by weight, preferably 0.5 % by weight, based on the total weight of the composition, more preferably is free of sodium cumenesulfonate, and most preferably free of cumenesulfonic acid and its salts.

16. The rinse-aid composition of any of aspects 1 to 15, which is free of any cationic surfactant.

17. The rinse-aid composition of any of aspects 1 to 16 which does not contain any further anionic surfactant in addition to component (b) in amounts of more than 1 % by weight, preferably more than 0.5 % by weight, based on the total weight of the composition, and more preferably is free of any further anionic surfactant.

18. The rinse-aid composition of any of aspects 1 to 17 which is free of any amphoteric surfactant.

19. The rinse-aid composition of any of aspects 1 to 18 which does not contain any further nonionic surfactant in addition to components (a), (c) and impurities introduced with (b) in amounts of more than 1 % by weight, preferably more than 0.5 % by weight, based on the total weight of the composition, and more preferably is free of any further nonionic surfactant.

20. The rinse-aid composition of any of aspects 1 to 19 comprising:

1 to 11 % by weight, preferably 3 to 9 % by weight of fatty alcohol ethoxylate propoxylate (a),

> 0.5 to 5 % by weight, preferably 0.8 to 3.5 % by weight of phosphoric acid ester (b),

> 0 to 3 % by weight, preferably 0.2 to 2 % by weight of fatty alcohol ethoxylate (c), and

water in an amount adding up to 100 % by weight,

each based on the total weight of the composition.

21. The rinse-aid composition of any of aspects 1 to 20, wherein the fatty alcohol ethoxylate propoxylate (a) is not end-capped with a methyl group, preferably not end-capped with an alkyl group.

22. The rinse-aid composition of any of aspects 1 to 21 wherein the fatty alcohol ethoxylate propoxylate (a) is a mixture of compounds according to formula (II)

         R³-O-B-R⁴     (II),

wherein

R³ is a residue of a fatty alcohol,

R⁴ is selected from H and C₁ to C₅ alkyl, preferably R⁴ is H,

B is -(C₂H₄O)_x-(C₃H₆O)_y- or -(C₃H₆O)_y-(C₂H₄O)_x-,

wherein x has an average value of from 1 to 16 and y has an average value of from 1 to 16, including a random distribution of -C₂H₄O- and
-C₃H₆O- units.

23. The rinse-aid composition of aspect 22, wherein R³ is selected from C₈ to C₂₂ alkyl, preferably C₁₀ to C₂₀ alkyl, more preferably C₁₀ to C₁₈ alkyl, and most preferably C₁₂ to C₁₆ alkyl.

24. The rinse-aid composition of any of aspects 22 or 23, wherein R³ comprises an even number of carbon atoms.

25. The rinse-aid composition of any of aspects 22 to 24, wherein R³ comprises a linear carbon chain.

26. The rinse-aid composition of any of aspects 22 to 25, wherein R³ is C₁₂ alkyl and/or C₁₄ alkyl, preferably the fatty alcohol ethoxylate propoxylate (a) is a mixture of compounds of formula (II) wherein R³ is C₁₂ alkyl and compounds (II) wherein R³ is C₁₄ alkyl.

27. The rinse-aid composition of any of aspects 22 to 26, wherein x has an average value of from 2 to 15, preferably from 2 to 12, more preferably from 3 to 10, and most preferably from 4 to 8; and y has an average value of from 2 to 15, preferably from 2 to 12, more preferably from 3 to 10, and most preferably from 3 to 7.

28. The rinse-aid composition of aspect 27, wherein x has an average value of from 4 to 6, preferably about 5, and y has an average value of from 3 to 5, preferably about 4.

29. The rinse-aid composition of any of aspects 22 to 28, wherein x is larger than y.

30. The rinse-aid composition of any of aspects 22 to 29, wherein the sum of x and y is in the range from 2 to 20, preferably from 4 to 14, more preferably from 7 to 11, and most preferably about 9.

31. The rinse-aid composition of any of aspects 1 to 30, wherein the phosphoric acid ester (b) is a mixture of monoesters (Ia) and diesters (Ib)

32. The rinse-aid composition of any of aspects 1 to 31, wherein R¹ comprises a linear carbon chain and is selected from C₆ to C₂₀ alkyl, preferably C₆ to C₁₆ alkyl, more preferably C₈ to C₁₄ alkyl, and most preferably C₈ to C₁₂ alkyl.

33. The rinse-aid composition of aspect 31 or 32 referring back to aspect 31, wherein the molar ratio of monoesters (Ia) to diesters (Ib) is in the range from 1:1 to 4:1, preferably from 1.5:1 to 3.5:1, more preferably from 1.8:1 to 3.2:1, and most preferably from 2:1 to 3:1 such as from 2.3:1 to 2.9:1 or about 2.6:1.

34. The rinse-aid composition of any of aspects 1 to 33, wherein R¹ is C₈ alkyl and/or C₁₀ alkyl, preferably the phosphoric ester (b) is a mixture of compounds of formula (I), preferably (Ia) and (Ib), wherein R¹ is C₈ alkyl and compounds of formula (I), preferably (Ia) and (Ib), wherein R¹ is C₁₀ alkyl.

35. The rinse-aid composition of aspect 34, wherein the molar ratio of C₈ alkyl to C₁₀ alkyl in the mixture of compounds of formula (I) is in the range of from 40:60 to 60:40, preferably from 45:55 to 53:47.

36. The rinse-aid composition of any of aspects 1 to 35, wherein A is -(C₂H₄O)_m- and m has an average value of from 2 to 15, preferably from 2 to 12, more preferably from 3 to 10, and most preferably from 4 to 8.

37. The rinse-aid composition of aspect 36 , wherein m has an average value of from 4 to 6, preferably about 5.

38. The rinse-aid composition of any of aspects 1 to 31, wherein R¹ is the residue of an isoalkyl alcohol.

39. The rinse-aid composition of aspect 38, wherein R¹ is selected from C₁₂ to C₂₂ isoalkyl, preferably C₁₂ to C₂₀ isoalkyl, more preferably C₁₂ to C₁₈ isoalkyl, and most preferably C₁₂ to C₁₆ isoalkyl such as C₁₃ isoalkyl.

40. The rinse-aid composition of any of aspects 1 to 39, wherein R¹ comprises an even number of carbon atoms.

41. The rinse-aid composition of any of aspects 1 to 31 or 38 or 39, wherein R¹ comprises an uneven number of carbon atoms.

42. The rinse-aid composition of any of aspects 38 to 41 referring back to aspect 38 referring back to aspect 31, wherein the molar ratio of monoester (Ia) to diester (Ib) is in the range from 3:1 to 1:3, preferably from 2:1 to 1:2 such as from 1.5:1 to 1:1.5 or about 1:1.

43. The rinse-aid composition of any of aspects 38 to 42 referring back to 38, wherein A is -(C₂H₄O)_m- and m has an average value of from 4 to 15, preferably from 5 to 13, more preferably from 6 to 12, and most preferably from 7 to 11.

44. The rinse-aid composition of aspect 43 , wherein m has an average value of from 8 to 10, preferably about 9.

45. The rinse-aid composition of any of aspects 1 to 44, wherein the fatty alcohol ethoxylate (c) is not end-capped.

46. The rinse-aid composition of any of aspects 1 to 45, wherein the fatty alcohol ethoxylate (c) is a mixture of compounds according to formula (III)

         R⁵-O-E-R⁶     (III),

wherein

R⁵ is a residue of a fatty alcohol,

R⁶ is selected from H and C₁ to C₅ alkyl, preferably R⁶ is H,

E is -(C₂H₄O)_z-,

wherein z has an average value of from 1 to 22.

47. The rinse-aid composition of aspect 46, wherein R⁵ comprises from 8 to 30 carbon atoms, preferably from 10 to 26 carbon atoms, more preferably from 12 to 22 carbon atoms, and most preferably from 14 to 20 carbon atoms.

48. The rinse-aid composition of any of aspects 46 or 47, wherein R⁵ comprises an even number of carbon atoms.

49. The rinse-aid composition of any of aspects 46 to 48, wherein R⁵ comprises a linear carbon chain.

50. The rinse-aid composition of any of aspects 46 to 49, wherein R⁵ is selected from mono-, di- and polyunsaturated fatty alcohol residues.

51. The rinse-aid composition of aspect 50, wherein R⁵ is C₁₆ alkenyl, preferably monounsaturated, and/or C₁₈ alkenyl, preferably monounsaturated.

52. The rinse-aid composition of aspect 51, wherein the fatty alcohol ethoxylate (c) is a mixture of compounds (III) wherein R⁵ is the residue of palmitoleyl alcohol (16:1 = cis-9-hexadecen-1-ol) and compounds (III) wherein R⁵ is the residue of oleyl alcohol (18:1 = cis-9-octadecen-1-ol).

53. The rinse-aid composition of any of aspects 46 to 52, wherein z has an average value of from 2 to 20, preferably from 3 to 18, more preferably from 4 to 16, and most preferably from 5 to 14.

54. The rinse-aid composition of aspect 53, wherein z has an average value of from 6 to 12, preferably from 7 to 11, more preferably from 8 to 10, and most preferably about 9.

55. The rinse-aid composition of any of aspects 1 to 54, wherein the fatty alcohol ethoxylate propoxylate (a) has an average HLB value in the range from 4 to 11, preferably from 5 to 10, more preferably from 6 to 9, even more preferably from 6 to 8, and most preferably of about 7.

56. The rinse-aid composition of any of aspects 1 to 55, wherein the phosphoric acid ester (b) has an average HLB value in the range from 12.5 to 15.5, preferably from 13 to 15, more preferably from 13.5 to 14.5, even more preferably from 13.7 to 14.2, and most preferably of about 14.

57. The rinse-aid composition of any of aspects 1 to 56, wherein the fatty alcohol ethoxylate (c) has an average HLB value in the range from 11 to 14.5, preferably from 11.2 to 14, more preferably from 11.5 to 13.8, even more preferably from 11.8 to 13.5, still more preferably from 12 to 13.2, still more preferably from 12.5 to 13, and most preferably of about 12.7.

58. Use of the composition according to any of any of aspects 1 to 57 as a rinse aid in an automatic dishwasher.

59. A method of cleaning kitchenware and tableware in an automatic dishwasher comprising adding a composition according to any of aspects 1 to 57 in the rinsing step.

60. A method for preparing a composition according to any of aspects 1 to 57 comprising mixing the fatty alcohol ethoxylate propoxylate (a), the phosphoric acid ester (b), fatty alcohol ethoxylate (c), and water in any sequence.

Claims

1. An aqueous rinse-aid composition comprising:

a) a fatty alcohol ethoxylate propoxylate,

b) a phosphoric acid ester of an alkoxylated fatty alcohol being a mixture of compounds according to formula (I)

wherein

R¹ is each independently selected from residues of a linear fatty alcohol comprising at least 6 carbon atoms and residues of a branched fatty alcohol comprising at least 12 carbon atoms,

A is -(C₂H₄O)_m-(C₃H₆O)_n- Or -(C₃H₆O)_n-(C₂H₄O)_m-,
wherein m has an average value of from 1 to 15 and n has an average value of from 1 to 7 or is 0, including a random distribution of -C₂H₄O- and -C₃H₆O- units,

i = 1, 2 or 3, preferably 1 or 2,

j = 0, 1 or 2, preferably 1 or 2,

the sum of i + j = 3,

or salts thereof, and

c) a fatty alcohol ethoxylate.

2. The rinse-aid composition of claim 1 having a pH value within the range of from 1.8 to < 7, preferably from 2 to 5, more preferably from 2 to 4, even more preferably from 2.2 to 3, and most preferably of about 2.5.

3. The rinse-aid composition of any of claims 1 or 2, wherein the weight ratio of fatty alcohol ethoxylate propoxylate (a) to phosphoric acid ester (b) is less than 24:1, preferably less than 20:1, more preferably less than 15:1.

4. The rinse-aid composition of any of claims 1 to 3, which is free of citric acid, preferably free of any organic acid.

5. The rinse-aid composition of any of claims 1 to 4 comprising:

1 to 11 % by weight, preferably 3 to 9 % by weight of fatty alcohol ethoxylate propoxylate (a),

> 0.5 to 5 % by weight, preferably 0.8 to 3.5 % by weight of phosphoric acid ester (b),

> 0 to 3 % by weight, preferably 0.2 to 2 % by weight of fatty alcohol ethoxylate (c), and

water in an amount adding up to 100 % by weight,

each based on the total weight of the composition.

6. The rinse-aid composition of any of claims 1 to 5 wherein the fatty alcohol ethoxylate propoxylate (a) is a mixture of compounds according to formula (II)

         R³-O-B-R⁴     (II),

wherein

R³ is a residue of a fatty alcohol,

R⁴ is selected from H and C₁ to C₅ alkyl, preferably H,

B is -(C₂H₄O)_x-(C₃H₆O)_y- or -(C₃H₆O)_y-(C₂H₄O)_x-,

wherein x has an average value of from 1 to 16 and y has an average value of from 1 to 16, including a random distribution of -C₂H₄O- and
-C₃H₆O- units.

7. The rinse-aid composition of claim 6, wherein R³ is C₁₂ alkyl and/or C₁₄ alkyl, preferably the fatty alcohol ethoxylate propoxylate (a) is a mixture of compounds of formula (II) wherein R³ is C₁₂ alkyl and compounds (II) wherein R³ is C₁₄ alkyl.

8. The rinse-aid composition of any of claims 1 to 7, wherein the phosphoric acid ester (b) is a mixture of monoesters (Ia) and diesters (Ib)

9. The rinse-aid composition of any of claims 1 to 8, wherein R¹ comprises a linear carbon chain and is selected from C₆ to C₂₀ alkyl, preferably C₆ to C₁₆ alkyl, more preferably C₈ to C₁₄ alkyl, and most preferably C₈ to C₁₂ alkyl.

10. The rinse-aid composition of any of claims 1 to 9, wherein R¹ is C₈ alkyl and/or C₁₀ alkyl, preferably the phosphoric ester (b) is a mixture of compounds of formula (I), preferably (Ia) and (Ib), wherein R¹ is C₈ alkyl and compounds of formula (I), preferably (Ia) and (Ib), wherein R¹ is C₁₀ alkyl.

11. The rinse-aid composition of any of claims 1 to 8, wherein R¹ is selected from C₁₂ to C₂₂ isoalkyl, preferably C₁₂ to C₂₀ isoalkyl, more preferably C₁₂ to C₁₈ isoalkyl, and most preferably C₁₂ to C₁₆ isoalkyl such as C₁₃ isoalkyl.

12. The rinse-aid composition of any of claims 1 to 11, wherein the fatty alcohol ethoxylate (c) is a mixture of compounds according to formula (III)

         R⁵-O-E-R⁶     (III),

wherein

R⁵ is a residue of a fatty alcohol,

R⁶ is selected from H and C₁ to C₅ alkyl, preferably R⁶ is H,

E is -(C₂H₄O)_z-,

wherein z has an average value of from 1 to 22.

13. The rinse-aid composition of claim 12, wherein the fatty alcohol ethoxylate (c) is a mixture of compounds (III) wherein R⁵ is the residue of palmitoleyl alcohol (16:1 = cis-9-hexadecen-1-ol) and compounds (III) wherein R⁵ is the residue of oleyl alcohol (18:1 = cis-9-octadecen-1-ol).

14. Use of the composition according to any of any of claims 1 to 13 as a rinse aid in an automatic dishwasher.

15. A method of cleaning kitchenware and tableware in an automatic dishwasher comprising adding a composition according to any of claims 1 to 15 in the rinsing step.