EP0197434B1 - Rinsing agents for use in mechanical dish washing - Google Patents

Description

The invention relates to low-foaming and biodegradable rinse aids for machine dishwashing with good wetting and draining effects on hard surfaces.

In the case of automatic dishwashing, two rinse cycles with different types of products, usually separated by intermediate rinse cycles with pure water, are used. In the actual cleaning cycle, alkaline reacting agents are used to detach and emulsify the food residues. In the so-called rinse or rinse cycle, however, special rinse aid is 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 does not leave any visible residues, such as lime stains or other soiling.

Because of the strong movement of liquors in household and commercial dishwashers, the rinse aid must be as low-foaming as possible. Since the usual anionic surfactants, such as higher molecular weight alkyl sulfates or alkyl or alkyl aryl sulfonates, are known to have a strong tendency to foam and are therefore not suitable for this use, nonionic surfactants based on ethylene oxide adducts with fatty alcohols, alkylphenols or polypropylene glycols of relatively high molecular weights are preferred in practice .

In practice, however, it has been shown that these products are usually still not sufficiently low in foam in the concentration ranges required for a sufficient wetting effect. They lead, especially in commercial dishwashers with very high water circulation and the usual recirculation of the rinse liquor, which is around 80 ° C hot, into the main cleaning cycle with approx. 50 to 70 ° C and alkaline cleaning agent and into the dirt pre-cleaning zone, which is only 40 ° C warm, with all food soiling, easy to mechanical faults due to excessive and stable foaming. However, the same difficulties can also occur in household dishwashers. It is therefore usually necessary to add foam detergent to the rinse aid even when using relatively low-foaming ethylene oxide adducts. Such nonionic alkoxylation products which are sparingly water-soluble at rinsing temperatures are suitable, such as, for example, 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. However, such products have no wetting effect at application temperatures and therefore represent a burden on the rinse aid.

From the German patent specification 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 use of foam-suppressing ballast surfactants or other foam dampers unnecessary. These are rinse aids for machine dishwashing based on nonionic low-foaming surfactants containing adducts 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 of 10 to 20 carbon atoms had good biodegradability according to the requirements at the time, but no longer meets today's requirements.

Compared to the usual wash ware, such as porcelain dishes, cutlery and especially glasses, which are considered to be particularly difficult in this regard, the adducts mentioned show an excellent drainage and clear drying effect, but they can no longer be used because of the biodegradability which is no longer regarded as sufficient .

Because of the inadequate biodegradability, the alkylphenol polyethylene glycol phenyl ethers known from the US Pat. No. 3,255,117, which are preferably used, are only of limited use as nonionic surfactants. This publication does not convey any knowledge of the properties of the alkylol polyethylene glycol alkyl ethers which are also claimed as a whole since this has not been used.

From the German published patent application 25 56 544 such alkylol polyethylene glycol alkyl ethers are now known which have been etherified exclusively with a tert-butyl radical. They were used as a single compound in addition to other nonionic surfactants, among others in rinse aids for automatic dishwashing.

German patent application 3315951 already discloses the use of the compounds of the formula (I) according to the invention as foam-suppressing additives for low-foam cleaning agents. It is therefore also known that these are compounds with good alkali and acid stability, the biodegradability of which, according to the statutory methods of determination, is over 80% BiAS decrease. However, it is not apparent from the prior art that a specific mixture of end-capped alkyl polyethylene glycol ethers as the sole surfactant component in rinse aids, which are not considered cleaning agents, can be used for automatic dishwashing in the household and in commerce and, in addition to low-acid and, above all, alkali-resistant foam cause a good clear dry effect.

in der R1 einen geradkettigen oder verzweigten Alkylrest oder Alkenylrest mit 8 bis 18 Kohlenstoffatomen, R² einen Alkylrest mit 4 bis 8 Kohlenstoffatomen und n eine Zahl von 7 bis 16 bedeuten, im Gemisch mit endgruppenverschlossenen Alkylpolyethylenglykolether der allgemeinen Formel

in der R¹ einen geradkettigen oder verzweigten Alkylrest oder Alkenylrest mit 8 bis 18 Kohlenstoffatomen und R² einen Alkylrest mit 4 bis 8 Kohlenstoffatomen bedeuten, und m eine Zahl von 17 bis 23, vorzugsweise 18 bis 20 bedeutet, zu neuen schaumarmen Klarspülmitteln führt, die an sich keinen weiteren Tensidzusatz benötigen und qualitativ mit den bekannten oben genannten mindestens vergleichbar sind.Surprisingly, it has now been found that the use of end-capped alkyl polyethylene glycol ethers of the following general formula

in which R1 is a straight-chain or branched alkyl radical or alkenyl radical with 8 to 18 carbon atoms, R ^{2 is} an alkyl radical with 4 to 8 carbon atoms and n is a number from 7 to 16, in a mixture with end-capped alkyl polyethylene glycol ethers of the general formula

in which R ^{1 is} a straight-chain or branched alkyl radical or alkenyl radical with 8 to 18 carbon atoms and R ^{2 is} an alkyl radical with 4 to 8 carbon atoms, and m is a number from 17 to 23, preferably 18 to 20, leads to new low-foaming rinse aid which do not require any further surfactant addition per se and are qualitatively at least comparable to the known ones mentioned above.

In a special embodiment of the invention, polyglycol ethers of the formula described above are used in which n is a number from 8 to 14, preferably 9 to 12 and R ^{2 is} an n-butyl radical.

Although the ethers of the formula (II) only develop their low foaming above 45 ° C., so that their sole use in rinse aids would make little sense, they can, however, be excellently mixed with the lower ethoxylated ethers of the formula (I) to be used according to the invention and impart good wetting power to the rinse aid if there is little foam, which is particularly important for plastic dishes that are difficult to wet by nature. The mixing ratio of higher to lower ethoxylated ethers should be chosen so that the cloud point of the mixture is not higher than 45 ° C.

in der R¹ einen geradkettigen oder verzweigten Alkyl- oder Alkenylrest mit 8 bis 18 Kohlenstoffatomen, R² einen Alkylrest mit 4 bis 8 Kohlenstoffatomen und n eine Zahl von 7 bis 16 bedeuten, im Gemisch mit endgruppenverschlossenen Alkylpolyethylenglykolethern der Formel

in der R¹ und R² die für Formel angegebene Bedeutung haben und m eine Zahl von 17 bis 23 ist, wobei der Trübungspunkt des Gemisches aus Ethern der Formeln und II nicht höher als 45 °C liegt, als nichtionisches schaumarmes Tensiogemisch in Klarspülmitteln für die maschinelle Geschirreinigung in Haushalt und Gewerbe.The invention therefore relates to the use of end-capped alkyl polyethylene glycol ethers of the formula

in which R ^{1 is} a straight-chain or branched alkyl or alkenyl radical with 8 to 18 carbon atoms, R ^{2 is} an alkyl radical with 4 to 8 carbon atoms and n is a number from 7 to 16, in a mixture with end-capped alkyl polyethylene glycol ethers of the formula

in which R ¹ and R ^{2 have} the meaning given for formula and m is a number from 17 to 23, the cloud point of the mixture of ethers of the formulas and II being not higher than 45 ° C., as a nonionic low-foaming tensio mixture in rinse aid for mechanical dishwashing in the household and business.

The alkyl polyethylene glycol ether mixture used according to the invention is preferably used in the rinse aids in a concentration of 5 to 80, in particular 15 to 50% by weight and preferably in aqueous solution.

It is of course possible to blend the end-capped alkyl polyethylene glycol ethers with small amounts of other nonionic surfactants, for example to reduce the cost of the formulation, such as. B. with sufficiently degradable ethylene oxide adducts with fatty alcohols or adducts of propylene oxide or butylene oxide with fatty alcohol ethoxylates. As a result, the quality of the rinse aid according to the invention is not significantly changed. However, it is preferred to use mixtures of two or more different end-capped alkyl polyethylene glycol ethers without the addition of other nonionic surfactants.

The fatty alcohols n-octanol, n-decanol, N-dodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol, n-octadecen-9,10-ol (oleyl alcohol) can be used as starting material for the preparation of the polyglycol ethers of the formula I and II ) and oxo alcohols of the stated carbon number can be used individually or in a mixture.

To prepare the alkyl polyethylene glycol ethers to be used according to the invention, the fatty alcohols described above are advantageously reacted with ethylene oxide in a molar ratio of 1: 7 to 1:16 or in a molar ratio: 17 to 1:23, and the hydroxyl groups present in the reaction product obtained are then etherified. The reaction with ethylene oxide takes place under the known alkoxylation conditions, preferably in the presence of suitable alkaline catalysts. The etherification of the free hydroxyl groups is preferably carried out under the known conditions of Williamson's ether synthesis with straight-chain or branched C ₄ -C ₈ -alkyl halides, for example with n-butyl iodide, sec-butyl bromide, tert-butyl chloride, amyl chloride, tert-amyl bromide, n-hexyl chloride, n-heptyl bromide and n-octyl chloride. It may be expedient to use a stoichiometric excess of alkyl halide and alkali, for example from 100 to 200%, based on the number of hydroxyl groups to be etherified.

in der R¹ einen geradkettigen oder verzweigten Alkyl- oder Alkenylrest mit 8 bis 18 Kohlenstoffatomen, R² einen Alkylrest mit 4 bis 8 Kohlenstoffatomen, n eine Zahl von 7 bis 16 und m eine Zahl von 17 bis 23 bedeuten, in 20 bis 95, vorzugsweise 50 bis 85 Gew.-% Wasser löst.The invention therefore also relates to a process for the production of low-foaming rinse aids, for machine dishwashing in the household and business, which is characterized in that Alkanols or alkenols of the formula R ^L- OH, in which R ^{1 is} a straight-chain or branched alkyl or alkenyl radical having 8 to 18 carbon atoms, in a molar ratio of 1: 7 to 1:16, preferably 1: 8 to 1:14 and in particular 1 : 9 to 1:12 or in a molar ratio 1:17 to 1:23, preferably 1:18 to 1:20 in the presence of alkaline catalysts ethoxylated with ethylene oxide, then the free hydroxyl groups with straight-chain or branched C ₄ -C ₈ alkyl halides , preferably in an excess of 100 to 200%, based on the number of hydroxyl groups, etherified, the respective reaction products of the general formulas (I) and (II) are mixed with one another without the cloud point of the mixture exceeding 45 ° C. and 5 to 80 , preferably 15 to 50% by weight of the mixture thus obtained of end-capped alkyl polyethylene glycol ethers of the general formula

in which R ^{1 is} a straight-chain or branched alkyl or alkenyl radical with 8 to 18 carbon atoms, R ^{2 is} an alkyl radical with 4 to 8 carbon atoms, n is a number from 7 to 16 and m is a number from 17 to 23, in 20 to 95, preferably 50 to 85 wt .-% water dissolves.

To achieve sufficient temperature stability, however, it may be useful to incorporate solubilizing substances, such as, for example, mono- or polyhydric alkanols (for example ethanol, propanol, isopropanol, ethylene glycol, propylene glycol).

Hydrotropic substances, such as the alkali metal salts of low molecular weight alkylbenzenesulfonic acids, sodium cumene sulfonate, sodium xylene sulfonate or sodium toluenesulfonate, are also effective.

Depending on the cloud point of the surfactant mixture and the desired storage stability, the amounts of the solubilizing and / or hydrotropic substances can be between 0 and 40% by weight, based on the total rinse aid.

In addition, to prevent limescale deposits on the dishes when using non-softened water in the rinse cycle, up to 40, preferably from 10 to 35% by weight, based on the total rinse aid, of complexing agents, such as, for example, citric acid, tartaric acid, glycolic acid and / or commercial technical mixture of succinic acid, glutaric acid and adipic acid (Sokalan DCS (R) from BASF) can be used.

Complexing agents which have threshold-effective properties, such as 2-phosphonobutane-1,2,4-tricarboxylic acid (Bayhibit AM ^(R) ), can also be used, provided they are physiologically harmless. The use concentrations can also be lower and can be 0 to 10, preferably 2 to 7% by weight, based on the total rinse aid.

Furthermore, customary colorants, fragrances and preservatives can be added in the customary manner for use in rinse aids.

Some of the end-capped alkyl polyethylene glycol ethers used according to the invention are listed in Table 1 below:

The products, shown on product 1, were produced according to the following procedure.

676 g (1 mol) of adduct of 10 mol of ethylene oxide with n-dodecanol, 185 g (2 mol) of n-butyl chloride and 320 g of 75% strength by weight sodium hydroxide solution (6 mol of NaOH) were stirred at 120 ° C. for 4 hours. The cooled reaction mixture was mixed with 300 ml of water. The aqueous phase was then separated off. The organic phase was washed with water at approx. 50 ° C. until the washing liquid reacted neutrally. Unreacted butyl chloride and water were removed from the reaction product by heating to 50 ° C. in a water jet vacuum. 680 g of n-dodecylethylene glycol butyl ether (n-dodecanol + 10 EO + butyl) were obtained. The hydroxyl number of the product was 3.5.

Foaming behavior

In a foam ramming test (hand tamping method according to DIN 53902), the foaming behavior of the rinse aid surfactants (0.2 g / l) in 200 ml of an aqueous, alkaline detergent liquor consisting of alkali metal triphosphates, alkali silicates, potassium hydroxide and chlorine bleach (3 g / l perclin intensive liquid cleaner ^R ) of 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:

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

Biodegradability

The biodegradability of the adducts claimed was checked in the OECD screening test (RVO to the WM Act) and stated in the BiAS acceptance after 19 days.

Degradability was also measured in accordance with the GF test method specified in the Chemicals Act for «ready biodegradability according to the GF / BSB test regulation (COD / Chemical Oxygen Demand).

The determined degradation values according to both methods are shown in the following example.

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

example 1

• 12,5 % c_12-14-Fettalkohol + 17 EO + n-Butyl
• 12,5 % c_12-18-Fettalkohol + 10 EO + n-Butyl
• 3 % Na-Cumolsulfonat
• 72 % Wasser

A highly effective rinse aid for commercial dishwashers had the following composition (% by weight):

• 12.5% c _12-14 fatty alcohol + 17 EO + n-butyl
• 12.5% c _12-18 fatty alcohol + 10 EO + n-butyl
• 3% Na cumene sulfonate
• 72% water

The cloud point of the ether mixture was 38 ° C. In a commercial dishwasher, there was no disruptive foam at the existing detergent liquor temperature of 65 ° C. The clear dry effect at a dosage of 0.1 to 1.5 g / l was excellent, especially on plastic dishes that were difficult to wet:

Example 2

• 10% c _12-14 fatty alcohol + 20 EO + n-butyl
• 15% C _12-18 fatty alcohol + 10 EO + n-butyl
• 1% Na cumene sulfonate
• 74% water
• (all in% by weight)

With a dosage of the rinse aid of 0.1 to 1.5 g / l, a good clear drying effect, in particular on plastic dishes, was found both when used in a commercial and in a domestic dishwasher. The rinse aid is low-foaming above 44 ° C and also shows little foam when carried into the cleaning cycle of commercial dishwashers with low foam load at temperatures around 60 ° C.

Claims (10)

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

in which R¹ is a linear or branched alkyl radical or alkenyl radical containing from 8 to 18 carbon atoms, R² is an alkyl radical containing 4 to 8 carbon atoms and n is a number of from 7 to 16, in admixture with terminated alkyl polyethylene glycol ethers corresponding to the following formula

in which R¹ and R² have the meanings defined for formula I and m is a number of from 17 to 23, the cloud point of the mixture of ethers corresponding to formulae I and II being no higher than 45 °C, as a low-foaming nonionic surfactant mixture in rinse aids for domestic and institutional dishwashing machines.

2. The use of ether mixtures as claimed in claim 1 with the formulae I and II shown therein, in which R² is an n-butyl radical, n is a number of 8 to 14, preferably 9 to 12, and m is a number of 18 to 20.

3. The use of ether mixtures as claimed in claim 1 or 2 in quantities of from 5 to 80 % by weight and preferably in quantities of from 15 to 50 % by weight in aqueous solution.

4. The use of ether mixtures as claimed in any of claims 1 to 3 with addition of solubilizing and/or hydrotropic substances.

5. The use of ether mixtures as claimed in any of claims 1 to 4 with addition of complexing agents, such as citric acid, tartaric acid, glycolic acid and/or technical mixtures of succinic acid, glutaric acid and adipic acid in quantities of up to 40 % by weight and preferably in quantities of from 10 to 35 % by weight, based on the rinse aid as a whole.

6. The use of ether mixtures as claimed in any of claims 1 to 6 with addition of threshold-active complexing agents, such as 2-phosphonobutane-1,2,4-tricarboxylic acid in quantities of up to 10 % by weight and preferably in quantities of from 2 to 7 % by weight, based on the rinse aid as a whole.

7. A process for the production of low-foaming rinse aids for domestic and institutional dishwashing machines according to claim 1, characterized in that alkanols or alkenols corresponding to the formula R'-OH, in which R¹ is a linear or banched alkyl or alkenyl radical containing 8 to 18 carbon atoms, are ethoxylated with ethylene oxide in a molar ratio of from 1 : 7 to 1 : 16, preferably in a molar ratio of from 1 : 8 to 1 : 14 and more preferably in a molar ratio of from 1 : 9 to 1 : 12 or in a molar ratio of from 1 : 17 to 1 : 23 and preferably in a molar ratio of from 1 : 18 to 1 : 20 in the presence of alkaline catalysts, the free hydroxyl groups are then etherified with linear or branched C₄-C_B alkyl halides, preferably in an excess of from 100 to 200 %, based on the number of hydroxyl groups, the respective reaction products are mixed with one another without the cloud point of the mixture exceeding 45 °C and from 5 to 80 and preferably from 15 to 50 % by weight of the resulting mixture of terminated alkyl polyethylene glycol ethers corresponding to the general formula

in which R¹ is a linear or branched alkyl or alkenyl radical containing 8 to 18 carbon atoms, R² is an alkyl radical containing 4 to 8 carbon atoms, n is a number of from 7 to 16 and m is a number of from 17 to 23, are dissolved in 20 to 95 % by weight and preferably in 50 to 85 % weight water.

8. A process as claimed in claim 7, characterized in that the water is partially replaced by solubilizing and/or hydrotropic substances.

9. A process as claimed in claims 7 and 8, characterized in that the water is partially replaced by up to 40 % by weight and preferably by 10 to 35 % by weight, based on the rinse aid as a whole, of complexing agents, such as citric acid, tartaric acid, glycolic acid and/or a technical mixture of succinic acid, glutaric acid and adipic acid.

10. A process as claimed in claims 7 to 9, characterized in that the water is partially replaced by up to 10 % by weight and preferably by 2 to 7 % by weight, based on the rinse aid as a whole, of threshold-active complexing agents, such as 2-phosphonobutane-1,2,4-tricarboxyiic acid.