EP0300305B1 - Use of hydroxyalkylpolyethylene glycol ethers as rinsing agents for use in mechanical dish washing - Google Patents

Abstract

Hydroxyalkyl polyethylene glycol ethers of the general formula (I) <IMAGE> in which R<1> is hydrogen or a straight-chain alkyl radical with 1 to 16 C atoms, R<2> is a straight-chain or branched alkyl radical with 4 to 8 C atoms, R<3> is hydrogen or an alkyl radical with 1 to 16 C atoms and n is a number from 7 to 30, with the proviso that the total number of C atoms in R<1> and R<3> is 6 to 16, and mixtures of a plurality of such compounds are used in rinsing agents together with other additives normally used in such agents.

Description

The invention relates to the use of hydroxyalkyl polyethylene glycol ethers in rinse aids for machine dishwashing.

In the case of automatic dishwashing, two wash cycles, usually separated by intermediate wash cycles with pure water, are provided, in which different cleaning agents are used. In the actual cleaning cycle, alkaline cleaning agents are used to remove and emulsify food residues remaining on the dishes. In the so-called rinse or rinse cycle, on the other hand, special classic detergents are used. These are not cleaning agents, but should have a good wetting ability and reduce the surface tension of the rinse water to such an extent that it runs off the dishes like a film and leaves no visible residues that could lead to limescale marks or other soiling.

Because of the strong movement of liquors in dishwashers both in the household and in the commercial sector, the rinse aid must be as low-foaming as possible. Common anionic wetting agents, such as higher molecular weight Alkyl sulfates or alkyl or alkyl aryl sulfonates have a strong tendency to foam and are therefore not suitable as rinse aid. In practice, agents based on nonionic surfactants, for example of ethylene oxide adducts with fatty alcohols, alkylphenols or polypropylene glycols of relatively high molecular weights, are now widely used.

However, it has been shown that such rinse aids containing such nonionic surfactants are usually not yet sufficiently low in foam in the concentration ranges required for a sufficient wetting action. They easily lead to machine malfunctions due to excessive and stable foaming. This is the case - especially in commercial dishwashers with very high water circulation - because usually the rinse liquor, which is around 80 ° C hot, is returned to the main cleaning cycle and comes into contact with the alkaline cleaning agents at 50 to 70 ° C. Foam formation in these areas of the dishwashers is promoted by food residues present in the cleaning liquor. In household dishwashers, such difficulties only occur to a reduced extent, but in principle to the same extent.

It is therefore necessary to add foam detergent to the rinse aid even when using relatively low-foaming ethylene oxide adducts. Non-ionic alkoxylation products which are sparingly water-soluble at rinse aid temperatures are suitable as such. These include ethylene oxide adducts with higher alcohols, alkylphenols or amines with a low degree of ethoxylation or corresponding adducts of ethylene oxide and propylene oxide or propylene oxide and ethylene oxide in any order and in any ratio. However, such compounds have no wetting action at application temperatures and therefore represent a burden on the rinse aid.

From DE-PS 21 06 819, however, extremely low-foaming and biodegradable rinse aids are also known, which only contain active ingredients as wetting agents and make the addition of foam-suppressing ballast surfactants or other foam suppressants unnecessary. These are rinse aids for machine dishwashing based on nonionic, low-foaming surfactants with an adduct content of 5 to 20 moles of ethylene oxide and 1 to 10 moles of propylene oxide with secondary aliphatic alcohols with a linear alkyl chain with 10 to 20 C atoms. Compared to the usual items to be washed (porcelain plates, cutlery) but also on glasses, which are particularly difficult to rinse in the rinse cycle, the adducts mentioned show an excellent drainage and clear drying effect. The requirements for biodegradability at that time were met. However, the compounds mentioned do not meet current legal requirements for the degradability of compounds that get into wastewater.

in der

R¹

für einen geradkettigen Alkylrest mit 6 bis 16 C-Atomen,

R²

für einen geradkettigen oder verzweigten Alkylrest mit 4 bis 8 C-Atomen,

R³

für Wasserstoff oder einen Alkylrest mit 1 bis 8 C-Atomen und

n

für eine Zahl von 7 bis 12

stehen, sind aus der DE-OS 33 45 349 bekannt. Beschrieben in der gleichen Druckschrift ist auch die Verwendung der genannten Verbindungen als schaumdrückende Zusätze in schaumarmen Reinigungsmitteln. Wesentlicher Vorteil der beschriebenen Verbindungen (I) ist nicht nur ihre ausgeprägte Schaumarmut, sondern auch ihre gute Säure- und insbesondere Alkalistabilität, wie sie für Reinigungsmittel wegen der in solchen Mitteln regelmäßig vorhandenen hohen Alkalikonzentrationen zwingend erforderlich ist. Außerdem weisen die beschriebenen Verbindungen (I) eine ausgesprochen gute biologische Abbaubarkeit auf, die auch aktuellen gesetzlichen Erfordernissen noch zu entsprechen vermag.Hydroxyalkyl polyethylene glycol ethers of the general formula (I)

in the

R¹

for a straight-chain alkyl radical with 6 to 16 carbon atoms,

R²

for a straight-chain or branched alkyl radical having 4 to 8 carbon atoms,

R³

for hydrogen or an alkyl radical with 1 to 8 carbon atoms and

n

for a number from 7 to 12

are known from DE-OS 33 45 349. The use of the compounds mentioned as foam-suppressing additives in low-foam cleaning agents is also described in the same publication. A significant advantage of the compounds (I) described is not only their marked lack of foam, but also their good acid and, in particular, alkali stability, as is absolutely necessary for cleaning agents because of the high alkali concentrations regularly present in such agents. In addition, the compounds (I) described have an extremely good biodegradability, which is still able to meet current legal requirements.

Surprisingly, it has now been found that the compounds mentioned have a particularly good suitability as the sole surfactant component in rinse aids for machine dishwashing, since - as described in the prior art - they are not only acid and alkali-stable, but are also readily biodegradable and can be broken down characterize their pronounced low foam, but also - and this fact can be seen from the prior art - show an excellent clear drying effect due to their good wetting effect.

in der

R¹

für Wasserstoff oder einen geradkettigen Alkylrest mit 1 bis 16 C-Atomen,

R²

für einen geradkettigen oder verzweigten Alkylrest mit 4 bis 8 C-Atomen,

R³

für Wasserstoff oder einen Alkylrest mit 1 bis 16 C-Atomen und

n

für eine Zahl von 7 bis 30

stehen, mit der Maßgabe, daß die Gesamtzahl der in R¹ und R³ enthaltenen C-Atome 6 bis 16 beträgt, in Klarspülmitteln für die maschinelle Geschirreinigung neben weiteren, üblicherweise in derartigen Mitteln verwendeten Zusätzen.The invention therefore relates to the use of hydroxyalkyl polyethylene glycol ethers of the general formula (I)

in the

R¹

for hydrogen or a straight-chain alkyl radical with 1 to 16 carbon atoms,

R²

for a straight-chain or branched alkyl radical having 4 to 8 carbon atoms,

R³

for hydrogen or an alkyl radical with 1 to 16 carbon atoms and

n

for a number from 7 to 30

stand, with the proviso that the total number of carbon atoms contained in R¹ and R³ is 6 to 16, in rinse aid for machine dishwashing along with other additives commonly used in such agents.

The compounds used according to the invention correspond to the general formula (I). In this general formula (I), R1 represents a straight-chain alkyl radical having 1 to 16 carbon atoms. As such alkyl radicals are the radicals methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl , n-Pentadecyl and n-Hexadecyl in question. In a preferred embodiment of the present invention, hydroxyalkyl polyethylene glycol ethers of the general formula (I) are used, in which R 1 represents a linear alkyl radical having 12 to 16 carbon atoms. Such hydroxyalkyl polyethylene glycol ethers of the general formula (I), when used in rinse aids, give the rinsing water a particularly good drainage behavior.

In the above-mentioned general formula (I) of the compounds which can be used according to the invention, R² represents a straight-chain or branched alkyl radical having 4 to 8 carbon atoms. The residues n-butyl, n-pentyl, n-hexyl, n-heptyl and n-octyl and the respective branched isomers of the alkyl residues mentioned are thus suitable. Since alcohols are used as starting materials for the preparation of the compounds of the general formula (I), the alkyl radical of which corresponds to the radical R 2 in the abovementioned general formula (I), the linear or branched alcohols with 4 to 8 C are therefore preferred for the preparation Atoms in the alkyl radical in question. These include the alcohols from the group n-butanol, i-butanol, n-amyl alcohol, 9-amyl alcohol, n-hexanol as well as the remaining isomeric hexanols, n-heptanol and their branched chain isomers as well as n-octanol and its branched chain isomers, e.g. 2-ethylhexanol to understand. For the preparation of the compounds of the general formula (I), which is described in more detail below, the alcohols mentioned can be used individually or in a mixture. The consequence of this is that the compounds of the general formula (I) are also formed not only as individual compounds but also as mixtures. Mixtures of the compounds are therefore also suitable for the use of the compounds of the general formula (I) mentioned in rinse aid; This embodiment is also encompassed by the present invention. In a particularly preferred embodiment of the use according to the invention, compounds of the general formula (I) are used in which R 2 is a n-butyl radical.

According to the use according to the invention, compounds of the general formula are used in rinse aids (I) used in which R³ is hydrogen or a straight-chain alkyl radical having 1 to 16 carbon atoms. In addition to hydrogen, the same alkyl radicals as for R¹ are suitable as the substituent R³.

In a preferred embodiment of the use according to the invention, the use of hydroxyalkyl polyethylene glycol ethers of the general formula (I) is provided in which R 1 is a linear alkyl radical having 12 to 16 carbon atoms and R 3 is hydrogen. Such compounds result in particularly good rinse aid effects: they are also accessible from corresponding epoxides in which the oxirane ring is terminal and which consequently can be converted particularly well into compounds of the general formula (I).

In the general formula (I) of the hydroxyalkyl polyethylene glycol ethers which can be used according to the invention, n stands for a number in the range from 7 to 30. This means nothing other than that - in the preparation of the compounds of the general formula (I) - the starting alcohol from the group mentioned above is ethoxylated in a molar ratio of 1: 7 to 1:30 with ethylene oxide. The corresponding number of recurring ethoxy units then also results for the compounds of the general formula (I) used according to the invention. Compounds (I) whose general formula n stands for a number in the range from 8 to 16 are preferably used. Because of the good wetting behavior, particularly good rinse aid effects are achieved with such compounds (I), in the general formula of which n stands for a number in the range from 9 to 14.

As described above, linear or branched alcohols having 4 to 8 carbon atoms are used as starting material for the preparation of the hydroxyalkyl polyethylene glycol ethers of the general formula (I), it being possible for the alcohols to be present both individually and in a mixture, for example in a mixture of several isomers to use. The reaction partner of the alcohols mentioned is then ethylene oxide, the molar ratio of the reaction partners of the ethoxylation reaction (alcohol: ethylene oxide) being in the range from 1: 7 to 1:30. Correspondingly, n in the starting materials for the preparation of the compounds of the general formula (I) used according to the invention is a number in the range from 7 to 30.

The alcohol ethoxylates obtained are reacted with epoxides having 10 to 18 carbon atoms to prepare the compounds (I) used according to the invention. Both 1,2-epoxides and compounds with an internal oxirane ring are suitable for this reaction. Epoxides with a terminal oxirane ring and 12 to 16 carbon atoms in the alkyl radical R have proven to be particularly suitable. Mixtures of epoxides of different chain lengths can also be used in the reaction to produce the compounds (I) used according to the invention. The reaction usually takes place in the presence of suitable, usually alkaline, catalysts. These are added to the reaction mixture in an amount of 0.1 to 1% by weight, based on the amount of epoxy used. The molar ratio of alcohol alkoxylate: epoxy is advantageously approximately in the range of 1: 1 for the reaction. During the reaction, which usually takes several hours, the reaction mixture becomes heated to temperatures in the range from 100 to 200 ° C., preferably in the range from 120 to 180 ° C. The degree of conversion can easily be determined by determining the epoxy content of the mixture. A reaction time of 4 to 8 hours at a temperature in the range from 150 to 170 ° C. is generally sufficient.

According to the invention the compounds of the above general formula (I) are used in rinse aids as the sole surfactant component. Rinse aids, which contain hydroxyalkyl polyethylene glycol ethers of the general formula (I) as the sole surfactant component, not only have the advantage of a pronounced lack of foam compared to the prior art, but also ensure that there are no problems with the requirements of biodegradability with regard to this surfactant component. In addition, such rinse aids show excellent wetting behavior; Even glasses whose rinsing was always considered problematic according to the state of the art are rinsed perfectly and can therefore be cleaned with good results even with dishwashers commonly used in commercial companies, i.e. rinse without stains and streaks.

It is of course also possible and falls under the use according to the invention to blend the hydroxyalkyl polyethylene glycol ethers of the general formula (I) with small amounts of other nonionic surfactants. This can be done, for example, to make the recipe cheaper. Suitable other nonionic surfactants are, for example, sufficiently degradable Ethylene oxide adducts with fatty alcohols or adducts of propylene oxide or butylene oxide with fatty alcohol ethoxylates. The quality of the rinse aid using the hydroxyalkyl polyethylene glycol ethers of the general formula (I) to be used according to the invention does not undergo any significant change, in particular no deterioration. As emphasized above, however, it is preferred to use a hydroxyalkyl polyethylene glycol ether of the general formula (I) or else mixtures of two or more such compounds in rinse aid without the addition of other nonionic surfactants.

The compounds (I) used according to the invention are used in the rinse aid in a concentration of 5 to 65% by weight, based on the total weight of the rinse aid. In accordance with the aqueous rinsing process, aqueous solutions are preferably used which enable the compounds (I) to be rapidly distributed or dissolved in the rinsing liquid. The preferred concentration range for the use of the compounds (I) is 15 to 50% by weight, based on the total weight of the rinse aid.

The use according to the invention of the compounds of the general formula (I) also corresponds to adding further substances to the rinse aid which are normally used in such rinse aid. To achieve sufficient temperature stability, it can be useful to incorporate solubilizing substances into the recipes. Monohydric or polyhydric alcohols are to be mentioned as such, of which ethanol, n-propanol, i-propanol, ethylene glycol and propylene glycol are preferred.

The alkali metal salts of low molecular weight alkylbenzenesulfonic acids, such as sodium cumene sulfonate, sodium xylene sulfonate or sodium toluenesulfonate, which are known from the prior art, are also suitable for this purpose.

The amounts of the solvent-imparting substances mentioned can be in the range between 0 and 40% by weight, based on the total rinse aid. The exact amount depends - among other parameters - on the cloud point of the surfactant used and the desired storage stability and can be varied within the limits mentioned without the excellent rinse effects achieved by the use of the compounds of the general formula (I) in any way influence.

In addition to the use of the compounds of the general formula (I), it is also possible to add further substances conventionally used in such rinse aids. In this context, complexing agents should be mentioned in particular, which are intended to prevent limescale deposits on the dishes when non-softened water is used in the rinse cycle. Such complexing agents can be added in amounts of 0 to 40% by weight, based on the total rinse aid, preferably in amounts of 10 to 35% by weight. Complexing agents which have proven themselves in this connection are, for example, citric acid, tartaric acid, glycolic acid, nitrilotriacetic acid or commercially available technical mixtures of succinic acid, glutaric acid and adipic acid (available under the name "Sokalan DCS" ®) from the company BASF). Complexing agents which have threshold-effective properties can also be used, provided they are physiologically harmless and can therefore be used in the area of machine washing of objects which come into contact with food. Examples of such complexing agents are 2-phosphonobutane-1.2.4-tricarboxylic acid and comparable compounds. The former is available, for example, under the name "Bayhibit AM" ®. The use concentrations can be lower than those for the above-mentioned complexing agents and can be 0 to 10% by weight, preferably 2 to 7% by weight, based on the total rinse aid.

It is also possible to add the usual colorants, fragrances and preservatives to the rinse aids in addition to the hydroxyalkyl polyethylene glycol ethers (I) used according to the invention and / or the substances mentioned above for use in rinse aids. These do not change the rinsing behavior of the compounds (I) in any way.

The invention is illustrated by the following examples.

example 1 Preparation of a compound of the general formula (I) (R¹ = n-dodecyl, R² = n-butyl, R³ = H, n = 10)

484 g (1 mole) of adduct of 10 moles of ethylene oxide with 1 mole of n-butanol, 227.5 g (1 mole) of linear 1,2-epoxytetradecane and 1.3 g of sodium methoxide (30% solution in methanol) were used in vacuo Removal of the methanol introduced with the catalyst was heated to 100 ° C. and then heated to 160 ° C. with stirring under an inert gas atmosphere for 6 hours. After cooling, the reaction product was neutralized with the equivalent amount of acetic acid and filtered.

The analytically determined hydroxyl number of the product was 80. The cloud point in water, determined according to DIN 53 917, was 28 ° C.

Examples 2 to 8

Further compounds of the general formula (I) were prepared in accordance with the procedure described in Example 1. The characteristic data for the structure and the cloud points of the compounds obtained, determined according to DIN 53 917 in water, can be found in Table 1 below. Table 1 Compounds of the general formula (I) according to Examples 2 to 8 (R³ = H) example R¹ R² n Cloud point in water (° C) 2nd n-octyl n-butyl 9 31 3rd n-tetradecyl n-butyl 9 24th 4th n-dodecyl n-hexyl 10th 25th 5 n-decyl n-butyl 11 31 6 n-dodecyl n-butyl 14 42 7 n-dodecyl n-butyl 19th 54 8th n-decyl n-butyl 29 66

Example 9 Determination of the foaming behavior

In a foam ramming test (hand tamping method according to DIN 53 902), the foam behavior of the rinse aid surfactants (0.2 g / l) in 200 ml of an aqueous, alkaline detergent liquor consisting of alkali metal phosphates, alkali silicates, potassium hydroxide and chlorine bleaching solution (3 g / l Perclin intensive liquid cleaner® from Henkel) KGaA). The water was softened, the temperature was 65 ° C. It was stamped 20 times in a measuring cylinder and the foam height was read after 10, 30 and 60 seconds.

Alkalinity and temperature correspond to the conditions in a commercial dishwasher.

In addition, 2 g / l freshly beaten fresh egg was added to these mixtures in order to test the food foam-suppressing effect. The results of the test are shown in Table 2 below. Table 2 Foaming behavior of the compounds of Examples 1 to 8 Verb from Ex. Foam height in ml without fresh egg Foam height in ml with fresh egg after 10 sec after 30 sec after 60 sec after 10 sec after 30 sec after 60 sec 1 10th 10th 10th 15-20 15 15 2nd 5 5 0-5 20th 15 15 3rd 0-5 0-5 0-5 10th 5-10 5-10 4th 10th 10th 10th 15 15 15 5 10th 5 5 10th 5-10 5-10 6 7 7 5 15 10th 8th 7 10th 9 7 22 18th 15 8th 43 40 35 60 50 45 without surfactant 0 0 0 160 160 160

Result:

These compounds were therefore extremely low-foaming and pressed the food foam well without the addition of foam-suppressing compounds.

Example 10 Biodegradability testing

The biodegradability of the adducts used was checked in the OECD Screening Test (RVO on the Detergent Act) and stated in the BiAS acceptance after 19 days.

Degradability was also measured according to the GF test method specified in the Chemicals Act "Ready biodegradability" according to the GF / BSB test regulation (COD / Chemical Oxygen Demand).

The values were determined for the compound from Example 1 and for two comparison products. They are shown in Table 3 below. Table 3 Results of the biodegradability test % BiAS decrease after 19 days % BOD / COD after 30 days Connection from Ex. 1 92 58 Comparative product I (sec.-C₁₁₋₁₅ fatty alcohol + 8 EO + 5 PO; cloud point: 33 ° C) 77 20th Comparative Product II (C₁₂₋₁₄ fatty alcohol + 5 EO + 4 PO; cloud point: 28 ° C) 96 40-50

Result:

The degradability requirement according to the EC directive is thus fully met.

Examples 11 to 15 Testing various rinse aids containing compounds of the general formula (I) in a practical test

Example 11

A rinse aid of the following composition was tested in a household dishwasher. 15% Compound from example 5 8th % Na cumene sulfonate 10% Citric acid (anhydrous) 0.3% Lemon Perfume Oil 66.7% Water (fully desalinated)

When used in a hot rinse cycle at 65 ° C, an excellent clear dry effect in the tested dosage range of 0.1 to 0.8 g / l rinse aid was found, especially on glasses.

Example 12

33% Compound from example 1 3% Na toluenesulfonate 64% Water (fully desalinated)

In a commercial multi-tank system, this recipe did not cause any disruptive foaming in all zones (65 ° C cleaning zone, 43 ° C pre-clearing zone with heavy contamination). The clear dry effect was good in the entire dosage range 0.1 to 1.3 g / l.

Example 13

8th % Compound from Example 8 17% Compound from example 1 10% Isopropanol 65% water

In this example, the compound from Example 8, which foams more strongly above 40 ° C., but has better wetting properties, was combined with the low-foam compound from Example 1 from 30 ° C., resulting in a low-foaming rinse aid from 40 ° C., plastic parts with good wetting properties.

The test was carried out at 0.8 g / l in a commercial multi-tank dishwasher, with good rinse aid results.

Example 14

A hydroxyalkyl polyethylene glycol ether (I) was blended with a fatty alcohol ethylene glycol propylene glycol ether and checked in a commercial refueling machine. 15% Compound from example 3 10% Fatty alcohol (C₁₂₋₁₄) + 5 EO + 4 PO 4% Na cumene sulfonate 10% citric acid 5% Sokalan DCS® (dicarboxylic acid mixture, see page 11, line 34) 56% water

The rinse aid was low-foaming from 30 ° C and, with 0.1 to 1.0 g / l, had a good clear-dry effect without disruptive foaming when cleaning soiled lunch dishes.

Example 15

25% Compound from example 6 1 % Na cumene sulfonate 1 % 2-phosphonobutane-1.2.4-tricarboxylic acid (Bayhibit AM®) 0.4% Na benzoate 72.6% water

The rinse aid was low in foam in the application liquor from 43 ° C. A good clear drying effect was achieved in both a household and a commercial dishwasher with 0.1 to 1.0 g / l.

Example 16 Comparative examination of the clear dry effect

As a comparison, the clear dry effect of two of the surfactants used according to the invention was compared to that of a less readily degradable surfactant (sec.-C₁₁₋₁₅ alcohol + 8 EO + 5 PO). The tests were carried out in a household dishwasher (softened water; 300 mg salt load) with one cleaning and one rinse cycle, with grades from 1 (very poor) to 10 (optimal rinse; highest possible grade). The dosage of the surfactants in the rinse aid was 0.02 to 0.1 g / l. Drinking glasses served as items to be washed, as they are most sensitive to stains, streaks and streaks. That grade 10 was not achieved here is due to the very critical grading and the fact that the water used was softened but not desalinated. Note 10 is only possible if demineralized water is used. Table 4 Evaluation of the clear dry effect Rinse aid Clear dry effect rating with a surfactant dosage (g / l) of 0.02 0.06 0.1 Connection from Ex. 5 5.8 6.0 5.7 Connection from Ex. 6 6.3 6.0 6.2 Comparative product (DE-PS 21 06 819; sec.-C₁₁₋₁₅ fatty alcohol + 8 EO + 5 PO; cloud point: 34 ° C 6.1 6.0 5.7

Result:

It was found that the clear dry effect grade for the very readily degradable hydroxyalkyl polyethylene glycol ethers (I) used according to the invention is comparable to better than that of the tested comparative product with a clearly less good biodegradability according to the GF / BSB test.

Claims (9)

1. The use of hydroxyalkyl polyethylene glycol ethers corresponding to the following general formula

   

   in which

   R¹   is hydrogen or a linear C₁₋₁₆ alkyl radical,

   R²   is a linear or branched C₄₋₈ alkyl radical,

   R³   is hydrogen or a C₁₋₁₆ alkyl radical and

   n   is a number of 7 to 30,

   with the proviso that the total number of carbon atoms in R¹ and R³ is 6 to 16,
   and of mixtures of such compounds in rinse aids for dish-washing machines in addition to other additives typically used in rinse aids.
2. The use of compounds corresponding to general formula (I) as claimed in claim 1, in which R¹ is a linear C₁₂₋₁₆ alkyl radical and R³ is hydrogen.
3. The use of compounds corresponding to general formula (I) as claimed in claim 1, in which R² is an n-butyl radical.
4. The use of compounds corresponding to general formula (I) as claimed in claim 1, in which n is a number of 8 to 16 and preferably a number of 9 to 14.
5. The use of compounds corresponding to general formula (I) as claimed in claim 1, in which R¹ is a linear C₁₂₋₁₆ alkyl radical, R² is an n-butyl radical, R³ is H and n is a number of 9 to 14.
6. The use of compounds corresponding to general formula (I) as claimed in claims 1 to 5 in aqueous solution in quantities of 5 to 65% by weight and preferably in quantities of 15 to 50% by weight, based on the total weight of the rinse aid.
7. The use of compounds corresponding to general formula (I) as claimed in claims 1 to 6 with addition of solubilizers and/or hydrotropes and/or complexing agents and/or threshold-active complexing agents.
8. The use claimed in claim 7, characterized in that citric acid, tartaric acid, glycolic acid and/or technical mixtures of succinic acid, glutaric acid and adipic acid are used as complexing agents in quantities of 0 to 40% by weight and preferably in quantities of 10 to 35% by weight, based on the rinse aid as a whole.
9. The use claimed in claim 7, characterized in that 2-phosphonobutane-1,2,4-tricarboxylic acid is added as the threshold-active complexing agent in a quantity of 0 to 10% by weight and preferably in a quantity of 2 to 7% by weight, based on the rinse aid as a whole.