EP0728180B1 - Additive for use in glass-bottle washing and its use in decreasing glass corrosion - Google Patents

Abstract

The invention concerns an additive for alkaline aqueous washing solutions for use in bottle-washing plants, the additive containing a combination of hydroxyoligocarboxylic acids and phosphonic acids and resulting in a reduction of glass corrosion during washing. The invention also concerns the use of the additive in washing glass-bottles.

Description

The invention relates to a new additive for aqueous alkaline cleaning solutions for machine bottle cleaning systems for glass bottles, especially for beverage bottles. The additive has the task of the alkaline bottle cleaning usually occurs glass corrosion to reduce. Further aspects of the invention relate to the use of the Additives in aqueous cleaning solutions for machine cleaning of Glass bottles.

Before refilling reusable glass beverage bottles, the Labels are removed and the bottles are cleaned thoroughly. In the Bottle cleaning machines of the bottling plants are used for this Usually strongly alkaline, sodium hydroxide-containing cleaning solutions are used. The alkali metal hydroxide content is usually in the range 0.5 to 5, in particular 1 to 3% by weight. When using suitable products and processes achieve the desired cleaning effect. An unwanted one The effect of bottle cleaning is glass corrosion. Underneath it is understood that the surface of the glass bottles is chemically attacked becomes what leads to surface roughness. A sequela is common difficult cleaning of the rough surface and the risk of growth of microorganisms in cracks and holes in the surface. From the It is known from practice and from laboratory tests that the corrosiveness of those containing sodium hydroxide Cleaner solutions due to an increased proportion of sodium carbonate increases.

Given the number of possible refill cycles for reusable glass bottles is limited, among other things, by glass corrosion during cleaning, There is a need for additives that are used as additives in cleaning solutions reduce glass corrosion. The object of the invention is therefore to an active ingredient combination for aqueous alkaline cleaning solutions to provide for the mechanical cleaning of glass bottles, which, in addition to cleaning-enhancing properties, reduce the Glass corrosion contributes.

In a further aspect, the object of the invention is this Formulate active ingredient combination in the form of a concentrate that as Additive can be added to the aqueous alkaline cleaning solution on site can.

Aliphatic hydroxymono-, hydroxydi- or hydroxytricarboxylic acids with 3 up to 6 carbon atoms and 1 to 5 hydroxyl groups are more technical as components Cleaner known. It is also known to use cleaning solutions containing mineral diphosphonic acids of the general formula (I) given below, aminomethylenephosphonic acids of the general formula (II) or phosphonocarboxylic acids to add the general formula (III). It is assumed that the acids or their anions complexing properties in particular compared to the hardening ions of water. The above Phosphonic and phosphonocarboxylic acids also show so-called hardness-stabilizing (scale-inhibiting) properties.

For example, DE-C-23 25 829 describes a sequestering agent for 2- and 3-valent cations in the form of a mixture of 1-hydroxyethane-1,1-diphosphonic acid, Aminotrimethylene phosphonic acid and 2-phosphonobutane 1,2,4-tricarboxylic acid or their water-soluble salts. This font contains detailed information about which geminal diphosphonic acids, aminomethylene phosphonic acids and phosphonocarboxylic acids as a sequestering agent combination can be chosen. The one in this document, hereby expressly is made the subject of the present disclosure Phosphonic acid types are also in the sense as phosphonic acid components of the present invention.

The use of hydroxyalkanoligocarboxylic acids as complexing agents in technical alkaline cleaners are also known. For example W092 / 08824 discloses an aqueous alkaline cleaner for aluminum a pH between 10 and 12, which is an alkaline builder component, Aminoalkyl or hydroxyalkyldiphosphonic acids, surfactants and complexing agents for aluminum contains. As complexing agents for aluminum, among others Gluconate and tartate indicated. From the German Patent application DE-A-42 32 612 is the use of a combination from a phosphonic acid, an oxidizing agent and at least one short-chain organic carboxylic acid, selected from among others tartaric acid and citric acid, in acidic aqueous solutions that have a pH in the range have from 0 to 3 for the removal of magnetite deposits in water-bearing Systems known.

in der

n für eine ganze Zahl von 2 bis 30,

R^a für eine geradkettigen oder verzweigten, gesättigten oder ungesättigten Alkylrest mit 8 bis 24 C-Atomen und R^b für eine Gruppe -(CH₂-CH₂-O)_m-H

oder eine Gruppe

steht, wobei

R^C einen Alkylenrest mit 2 bis 6 C-Atomen,

m, x und y jeweils eine ganze Zahl von 0 bis 30 bedeuten.

DE-A-36 03 579 discloses acidic, phosphoric acid-containing cleaner concentrates which contain ethoxylated fatty amines of the general formula (V) as a constituent essential to the invention.

in the

n for an integer from 2 to 30,

R ^a for a straight-chain or branched, saturated or unsaturated alkyl radical having 8 to 24 carbon atoms and R ^b for a group - (CH ₂ -CH ₂ -O) _m -H

or a group

stands, where

R ^{C is} an alkylene radical with 2 to 6 C atoms,

m, x and y each represent an integer from 0 to 30.

The concentrates also contain a combination of different ones Phosphonic acids represented by the general formulas given below I, II and III are writable, and partly gluconic acid. It is the total phosphonic acid content is greater than the gluconic acid content.

From the German patent application DE-A-43 24 396 cleaning agents are included Known high wetting capacity, preferably for cleaning plastic surfaces be used. As constituents essential to the invention they contain monoamino or diaminomono or dicarboxylic acids or their Amides in combination with longer chain carboxylic acids and non-ionic Surfactants. Optional components in these cleaners can be: hydroxypolycarboxylic acids such as tartaric acid and citric acid, geminal diphosphonic acids such as 1-hydroxyethane-1,1-diphosphonic acid, aminophosphonic acids and phosphonopolycarboxylic acids. Furthermore, these cleaners can be used as builder substances Contain alkali metal hydroxides.

Surprisingly, it was found that a combination of hydroxyoligocarboxylic acids and as a sequestering agent of known phosphonic acids in certain proportions by alkaline, carbonate Cleaner solutions caused glass corrosion significantly reduced. Because of the known complexing properties of these active ingredients would be rather one increased corrosion rate was expected.

a) 7 bis 25 Gew.-%, bezogen auf die freie Säure, einer oder mehrerer aliphatischer Hydroxymono-, Hydroxydi- oder Hydroxytricarbonsäuren mit mindestens 2 und bis zu 6 C-Atomen und 1 bis 5 Hydroxygruppen und/oder aliphatischer Monoaminomonocarbonsäuren oder -dicarbonsäuren oder Diaminomonocarbonsäuren oder -dicarbonsäuren mit jeweils mindestens 2 und bis zu 6 C-Atomen oder jeweils deren wasserlösliche Salzen,

b) 1 bis 12 Gew.-%, bezogen auf die freie Säure, einer oder mehrerer geminaler Diphosphonsäuren der allgemeinen Formel (I)

wobei R einen Alkylrest mit 1 bis 5 C-Atomen und Z Wasserstoff, eine Hydroxy- oder eine Aminogruppe bedeuten,
und/oder einer oder mehrerer Aminomethylenphosphonsäuren der allgemeinen Formel (II)

wobei X und Y unabhängig voneinander Wasserstoff oder eine Alkylgruppe mit 1 bis 4 C-Atomen, R¹ und R² -PO₃H₂ oder eine Gruppe der Formel

und R³ -PO₃H₂ bedeuten,
und/oder einer oder mehrerer Phosphonocarbonsäuren der allgemeinen Formel (III)

wobei R' Wasserstoff, einen Alkylrest mit 1 bis 4 C-Atomen oder eine Gruppe -CH₂-CH₂-COOH bedeuten,
oder jeweils deren wasserlösliche Salze,

c) 63 bis 92 Gew.-% Wasser oder einer wäßrigen Lösung weiterer Hilfsstoffe,

wobei die Gesamtkonzentration der Carbonsäuren der Gruppe a) nicht kleiner ist als die Gesamtkonzentration der Phosphonsäuren der Gruppe b).In a first aspect, the invention describes an additive in the form of an aqueous solution for addition to alkaline cleaning baths for the mechanical cleaning of glass bottles, consisting of

a) 7 to 25 wt .-%, based on the free acid, of one or more aliphatic hydroxymono-, hydroxydi- or hydroxytricarboxylic acids with at least 2 and up to 6 carbon atoms and 1 to 5 hydroxyl groups and / or aliphatic monoaminomonocarboxylic acids or dicarboxylic acids or diaminomonocarboxylic acids or dicarboxylic acids each having at least 2 and up to 6 carbon atoms or their water-soluble salts,

b) 1 to 12% by weight, based on the free acid, of one or more geminal diphosphonic acids of the general formula (I)

where R is an alkyl radical having 1 to 5 carbon atoms and Z is hydrogen, a hydroxyl or an amino group,
and / or one or more aminomethylenephosphonic acids of the general formula (II)

where X and Y independently of one another hydrogen or an alkyl group having 1 to 4 carbon atoms, R ¹ and R ² -PO ₃ H ₂ or a group of the formula

and R ^{3 is} -PO ₃ H ₂ ,
and / or one or more phosphonocarboxylic acids of the general formula (III)

where R 'is hydrogen, an alkyl radical having 1 to 4 carbon atoms or a group -CH ₂ -CH ₂ -COOH,
or their water-soluble salts,

c) 63 to 92% by weight of water or an aqueous solution of further auxiliaries,

wherein the total concentration of the carboxylic acids of group a) is not less than the total concentration of the phosphonic acids of group b).

The additive preferably contains 10 to 20% by weight, based on the free Acid, one or more of the carboxylic acids of group a) or their water-soluble Salts and 2 to 6% by weight, based on the free acid, one or more of the phosphonic acids of group b) or their water-soluble salts and 74 to 88 % By weight of water or an aqueous solution of further auxiliaries.

Since the additive is intended as an additive to an alkaline cleaning solution , the acids which can be used according to the invention are in the application solution in the form of their anions, regardless of whether the additive is them contains as free acids or as water-soluble salts. If you put the carboxylic acids of group a) and / or the phosphonic acids of group b) as water-soluble Salts, the alkali metal or ammonium salts are special suitable, preferably sodium salts are used. The term "Water-soluble" is to be understood to mean that the salts in the aqueous Phase of the additive in the concentration ranges mentioned above, based on the free acids, are soluble.

Hydroxyacetic acids of group a) include, in particular, hydroxyacetic acid, Lactic acid, gluconic acid, tartronic acid, malic acid, tartaric acid and citric acid into consideration. Furthermore, amino carboxylic acids are according to the invention of group a). The naturally occurring alpha amino acids or Amino acid derivatives are usually those with the amino group Carbon atom chiral and are in the L-form. Although for the chiral L-amino acids for the technical purpose according to the invention offer no particular advantage, they are considered natural or nature-identical Active ingredients are preferably used. Accordingly, as amino acids in the form of their racemates or in optically active form, for example use find: glycine, alanine, valine, leucine, isoleucine, beta-alanine, gamma-aminobutyric acid, epsilon aminocaproic acid, glutamine, glutamic acid, Aspartic acid, aminomalonic acid, aminoadipic acid and 2-amino-2-methylpentanedioic acid. The amino acids can also carry hydroxyl groups. Examples include serine and threonine.

It is particularly advantageous if the additive is 2 to 4, preferably 3 different carboxylic acids and especially hydroxycarboxylic acids from the group a) contains, the combination of gluconic acid, lactic acid and citric acid leads to particularly positive results. It is cheap if the additive is gluconic acid, lactic acid and citric acid or their water-soluble salts in a weight ratio of 1: (0.5 to 1.5): (0.5 to 1.5), preferably in a weight ratio of 1: (0.7 to 1.0): (0.8 to 1.2) contains.

Formel (I): 1-Aminoethan-1,1-diphosphonsäure und 1-Hydroxyethan-1,1-diphosphonsäure,

Formel (II): Ethylendiamintetramethylenphosphonsäure, Diethylentriaminpentamethylenphosphonsäure, Aminotri-(2-propylen-2-phosphonsäure), Aminotrimethylenphosphonsäure,

Formel (III): Phosphonobernsteinsäure, Methylphosphonobernsteinsäure, 2-Phosphonobutan-1,2,4-tricarbonsäure.

Suitable phosphonic acids are listed in DE-C-23 25 829. Accordingly, the phosphonic acids of group b) or their water-soluble salts can preferably be selected from the following groups:

Formula (I): 1-aminoethane-1,1-diphosphonic acid and 1-hydroxyethane-1,1-diphosphonic acid,

Formula (II): ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, aminotri- (2-propylene-2-phosphonic acid), aminotrimethylenephosphonic acid,

Formula (III): phosphonosuccinic acid, methylphosphonosuccinic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid.

It is again advantageous if the additive or phosphonic acids whose water-soluble salts contain the general formula (I) and / or (III), preferably at least one phosphonic acid of the formulas (I) and (III), in particular 1-hydroxyethane-1,1-diphosphonic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid, be used.

A preferred additive is characterized in that it is a phosphonic acid or their water-soluble salts of the general formulas (I) and (III) in a weight ratio of 1:10 to 10: 1, preferably 1: 1 to 10: 1, in particular 6: 1 to 9: 1 contains.

It has proven advantageous to use certain weight ratios between the total content of the carboxylic acids of group a) and the total content the phosphonic acids of group b). Particularly favorable values Glass corrosion was found when the weight ratio of carboxylic acids of group a) to the phosphonic acids of group b) in the range between 1: 1 to 5: 1, preferably in the range 2: 1 to 4: 1.

The effect according to the invention is already achieved if the additive is except the above-mentioned components from groups a) and b) only Contains water. Depending on the application conditions, however, it can be advantageous be to add other additives to the water phase of the additive. Below in particular defoamers fall to those involved in the cleaning of protein Glass bottles often contain contaminants Fight foam. Accordingly, an aqueous solution c) is preferably one Defoamer solution used, it being recommended in the context of the invention is that the defoamer has a proportion based on the total additive from 1 to 25, preferably 10 to 20 and in particular 13 to 18% by weight matters.

The defoamer can be selected empirically depending on the type of contamination of the glass bottles. Those polyglycol ethers which are recommended in EP-B-124 815 as foam-suppressing additives in low-foam cleaning agents have proven successful. Accordingly, the defoamer is preferably selected from the group of polyethylene glycol ethers of the general formula (IV) R ⁴ -O- (CH ₂ -CH ₂ -O) _n -R ⁵ in which R ^{4 is} a straight-chain or branched alkyl or alkenyl radical with 8 to 18 C atoms, n is a number from 7 to 12, preferably from 8 to 10, and R ^{5 is} an alkyl radical with 4 to 8 C atoms, in particular with 4 C atoms mean.

It is known the cleaning solutions for machine bottle washers to add further surface-active auxiliaries, for example have a positive effect on the detachment behavior of the labels. Therefor nonionic surfactants can be based on ethoxylation and / or propoxylation products of fatty alcohols or fatty amines. A Particularly suitable product group from ethoxylated fatty amines is in the DE-A-36 03 579 cited above. The ones described there Fatty amine ethoxylates are also used as additives to increase cleaning performance the additives of the invention are suitable. In particular come as surface-active auxiliaries reaction products of fatty amines with 10 to 18 carbon atoms with 8 to 16 mol ethylene oxide into consideration. It is favorable if that or the nonionic surfactants in the aqueous solution c) in a are present in such an amount that they relate to the total additive Make up proportion of 1 to 6, preferably from 2 to 4 wt .-%.

The polyether chain obtained by alkoxylation of the defoaming and of the surface-active auxiliaries can be conventional or so-called there is a "narrow" homolog distribution. A way to manufacture of alkoxylation products with a narrow homolog distribution for example in DE-A-38 43 713.

For analytical control and adjustment of the drug concentration in the detergent bath, it is helpful if the ready-to-use Cleaning solution or the concentrated additive for this analytical contains easily determinable lead substances. As such a key substance For example, a soluble iodide, especially potassium iodide, comes in Consider its content in the bath solution by iodometric titration can be easily determined. Accordingly, it is preferred that the additive contains such a lead substance in a concentration that is in the diluted bath solution can be easily determined, but not too application or wastewater problems. For example, the invention Contain additive 0.1 to 0.5 wt .-% potassium iodide.

In a further aspect, the invention relates to the use of the additive in an aqueous cleaning solution containing alkali metal hydroxide mechanical cleaning of glass bottles. The use is characterized by that the cleaning solution has an active ingredient content of is adjustable in that the additive described above in such amounts to the cleaning solution that the content of the cleaning solution of carboxylic acids of group a) 100 to 1,000 mg / l, preferably 200 up to 800 mg / l, in particular 300 to 600 mg / l and of phosphonic acids Group b) is 50 to 400 mg / l, preferably 75 to 200 mg / l. Of the NaOH content of the cleaning solution is in the technically usual range of 0.5 to 5% by weight, preferably 1 to 3% by weight.

The use according to the invention can advantageously be carried out in this way be that the additive described above, which is an active ingredient concentrate represents, in the appropriate dosage of alkali metal hydroxide-containing Adds cleaning solution. The use according to the invention can of course also be done in that the individual Active substances in the above-mentioned concentration range of the cleaning solution separately admits. From the comparison of the concentrations of the Active substances of groups a) and b) in the finished cleaning solution and in Additive can be made by diluting the additive accordingly resulting concentrations of other excipients nonionic surfactants, defoamers and easily calculate lead substances.

The use is further characterized in that the bottles with the cleaning solution at temperatures between 40 and 90 ° C, preferably between 55 and 85 ° C for a period of 1 to 30 minutes, preferably 3 to 20 minutes in contact.

Embodiments

The invention is illustrated by the examples shown below. To check the relative corrosion rate of glass bottles with cleaning solutions according to the invention and with comparison solutions brand new 0.33 liter glass bottles (so-called Vichy bottles) for 24 Hours immersed in the respective solutions at 80 ° C and the weight loss determined in grams of removal per bottle. Even if these test conditions not the conditions on a technical bottle washer correspond, however, the relative corrosion effect of the individual Determine solutions.

To standardize the conditions, the test solutions included (except Cf. 1) 2 wt .-% sodium carbonate to the conditions in technical Approximately simulate baths. In practice, the sodium carbonate content of cleaning solutions fluctuate greatly. All test solutions included 2.5% by weight of NaOH, the components listed in Table 1 and water ad 100%. Comparative solution 1 was free of carbonate.

Table 1 shows the test results.

Examples 14 to 18

Additive concentrates were prepared in the form of aqueous solutions for addition to aqueous alkaline cleaning solutions for machine bottle cleaning by introducing the required amount of water and dissolving the other components therein with stirring at room temperature. A to K have the same meaning as in Table 1, L means potassium iodide. The active substance and auxiliary substance contents in the additive are stated in% by weight; the difference to 100% by weight is water. A B C. F G H I. K L Ex. 14 7 - 7 0.4 4th - - - 0.25 Ex. 15 6 2nd 6 0.5 3rd 0.5 10th 3rd - Ex. 16 5 4th 5 0.5 3.9 0.1 13 5 0.25 Ex. 16 5 4th 5 0.5 3.9 - 15 3rd - Ex. 17 6 5 6 0.5 4th - 15 3rd 0.25 Ex. 18 5 4th 5 1.5 3rd - 13 5 -

Claims (18)

1. An additive in the form of an aqueous solution for addition to alkaline cleaning baths for the machine washing of glass bottles, consisting of

   a) 7 to 25% by weight, based on the free acid, of one or more aliphatic hydroxymono-, hydroxydi- or hydroxytricarboxylic acids containing at least 2 and up to 6 carbon atoms and 1 to 5 hydroxy groups and/ or aliphatic monoamino-monocarboxylic acids or -dicarboxylic acids or diamino-monocarboxylic acids or -dicarboxylic acids containing at least 2 and up to 6 carbon atoms or water-soluble salts thereof,

   b) 1 to 12% by weight, based on the free acid, of one or more geminal disphosphonic acids corresponding to general formula (I):

   

   in which R is an alkyl radical containing 1 to 5 carbon atoms and Z is hydrogen, a hydroxy group or an amino group,
   and/or one or more aminomethylene phosphonic acids corresponding to general formula (II):

   

   in which X and Y independently of one another represent hydrogen or an alkyl group containing 1 to 4 carbon atoms, R¹ and R² represent -PO₃H₂ or a group corresponding to the formula

   

   and R³ represents -PO₃H₂
   and/or one or more phosphonocarboxylic acids corresponding to general formula (III):

   

   in which R' is hydrogen, an alkyl group containing 1 to 4 carbon atoms or a -CH₂-CH₂-COOH group,
   or water-soluble salts thereof,

   c) 63 to 92% by weight of water or an aqueous solution of other auxiliaries,

   the total concentration of the carboxylic acids of group a) being no lower than the total concentration of the phosphonic acids of group b).
2. An additive as claimed in claim 1, characterized in that it consists of 10 to 20% by weight, based on the free acid, of one or more of the carboxylic acids of group a) or water-soluble salts thereof and

   2 to 6% by weight, based on the free acid, of one or more of the phosphonic acids of group b) or water-soluble salts thereof and

   74 to 88% by weight of water or an aqueous solution of other auxiliaries.
3. An additive as claimed in one or both of claims 1 and 2, characterized in that alkali metal or ammonium salts, preferably sodium salts, are used as the water-soluble salts of the carboxylic acids of group a) and/or the phosphonic acids of group b).
4. An additive as claimed in one or more of claims 1 to 3, characterized in that the hydroxycarboxylic acids of group a) are selected from hydroxyacetic acid, lactic acid, gluconic acid, tartronic acid, malic acid, tartaric acid and citric acid.
5. An additive as claimed in one or more of claims 1 to 3, characterized in that the aminocarboxylic acids of group a) are selected from glycine, alanine, β-alanine, valine, leucine, isoleucine, γ-aminobutyric acid, εaminocaproic acid, glutamine, glutamic acid, aspartic acid, aminomalonic acid, aminoadipic acid and 2-amino-2-methylpentanedioic acid.
6. An additive as claimed in one or more of claims 1 to 3, characterized in that the amino acids of group a) carry additional hydroxyl groups and are preferably selected from serine and threonine.
7. An additive as claimed in one or more of claims 4 to 6, characterized in that it contains 2 to 4 and preferably 3 different carboxylic acids, preferably hydroxycarboxylic acids, more particularly gluconic acid, lactic acid and citric acid, or water-soluble salts thereof.
8. An additive as claimed in claim 7, characterized in that it contains gluconic acid, lactic acid and citric acid or water-soluble salts thereof in a ratio by weight of 1 : (0.5 to 1.5) : (0.5 to 1.5) and preferably in a ratio by weight of 1 : (0.7 to 1.0) : (0.8 to 1.2).
9. An additive as claimed in one or more of claims 1 to 8, characterized in that the phosphonic acids of group b) or water-soluble salts thereof are selected from the following groups:

   formula (I): 1-aminoethane-1,1-diphosphonic acid and 1-hydroxyethane-1,1diphosphonic acid,

   formula (II): ethylenediamine tetramethylene phosphonic acid, diethylenetriamine pentamethylene phosphonic acid, aminotri-(2-propylene-2-phosphonic acid), aminotrimethylene phosphonic acid,

   formula (III): phosphonosuccinic acid, methyl phosphonosuccinic acid, 2phosphonobutane-1 ,2,4-tricarboxylic acid.
10. An additive as claimed in claim 9, characterized in that it contains phosphonic acids or water-soluble salts thereof corresponding to general formula (I) and/or (III), at least one phosphonic acid corresponding to each of formulae (I) and (III), more especially 1-hydroxyethane-1,1-diphosphonic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid, preferably being used.
11. An additive as claimed in claim 10, characterized in that it contains a phosphonic acid or water-soluble salts thereof corresponding to each of general formulae (I) and (III) in a ratio by weight of 1:10 to 10:1, preferably in a ratio by weight of 1:1 to 10:1 and more preferably in a ratio of 6:1 to 9:1.
12. An additive as claimed in one or more of claims 1 to 11, characterized in that the ratio by weight of the carboxylic acids of group a) to the phosphonic acids of group b) is 1:1 to 5:1 and preferably 2:1 to 4:1.
13. An additive as claimed in one or more of claims 1 to 12, characterized in that a defoamer solution is used as the aqueous solution c).
14. An additive as claimed in claim 13, characterized in that the defoamer makes up from 1 to 25% by weight, preferably 10 to 20% by weight and more preferably 13 to 18% by weight of the additive as a whole.
15. An additive as claimed in one or both of claims 13 and 14, characterized in that the defoamer is selected from the group of polyethylene glycol ethers corresponding to general formula (IV): R⁴-O-(CH₂-CH₂-O)_n-R⁵ in which R⁴ is a linear or branched alkyl or alkenyl radical containing 8 to 18 carbon atoms, n is a number of 7 to 12 and preferably 8 to 10 and R⁵ is an alkyl radical containing 4 to 8 carbon atoms and more especially 4 carbon atoms.
16. An additive as claimed in one or more of claims 1 to 15, characterized in that the aqueous solution c) additionally contains one or more nonionic surfactants based on ethoxylation and/or propoxylation products of fatty alcohols or fatty amines, preferably ethoxylation products of fatty amines, more especially reaction products of fatty amines containing 10 to 18 carbon atoms with 8 to 16 moles of ethylene oxide, the nonionic surfactant(s) making up from 1 to 6% by weight and preferably from 2 to 4% by weight of the additive as a whole.
17. The use of the additive claimed in one or more of claims 1 to 16 for reducing the corrosion of glass in aqueous cleaning solutions for bottle washing machines having an alkali metal hydroxide content of 0.5 to 5% by weight and preferably 1 to 3% by weight, characterized in that the cleaning solutions have a content of active substances which can be adjusted by adding the additive to the cleaning solution in such quantities that the content of carboxylic acids of group a) in the cleaning solution is from 100 to 1,000 mg/l, preferably from 200 to 800 mg/l and more preferably from 300 to 600 mg/l and the content of phosphonic acids of group b) is from 50 to 400 mg/l and preferably from 75 to 200 mg/l.
18. The use claimed in claim 17, characterized in that the bottles are contacted with the cleaning solution for 1 to 30 minutes and preferably for 3 to 20 minutes at temperatures of 40 to 90°C and preferably at temperatures of 55 to 85°C.