DE3935374A1 - ALKYLPOLYETHYLENGLYKOLETHER AS FOAM-PRESSING ADDITIVES FOR CLEANERS - Google Patents

Abstract

The invention concerns the use, as foam-inhibiting additives in low-foam cleaning agents, of alkyl polyethyleneglycol ethers, without terminal OH groups, of the formula R<1>-O-(CH2CH2O)n-R<2> in which R<1> is a straight-chain, branched or cyclic alkyl or alkenyl group with 6-18 C-atoms, R<2> is an alkyl group with 4-8 C-atoms and n is a number between 3 and 6, prepared from ethylene oxide and a fatty alcohol, or mixture of fatty alcohols, containing an R<1> group and subsequent etherification with an alkyl halide containing an R<2> group, by ethoxylation of the fatty alcohol in the presence of calcined hydrotalcites as catalyst.

Description

The invention relates to the use of end group capped Alkyl polyethylene glycol ethers as foam-suppressing additives in low-foam Detergents.

Aqueous for use in trade and industry Detergents, especially those for cleaning metal, Glass, ceramic and plastic surfaces included in the Rule substances that are capable of undesirable foaming counteract. The use of foam-suppressing additives is in most cases due to the fact that they are different from the Detached substrates and accumulate in the cleaning baths Impurities act as foaming agents. In addition, the use of anti-foaming agents also required due to the fact be that the cleaning agents themselves contain ingredients that Undesired foam formation under the specified working conditions Give cause, for example anionic surfactants or at working temperature foaming nonionic surfactants.

DE-OS 33 15 951 describes the use of alkyl polyethylene glycol ethers of the general formula (Ia)

R¹-O- (CH₂CH₂O) _n -R² (Ia)

in the
R¹ is a straight-chain or branched alkyl radical or alkenyl radical with 8 to 18 C atoms,
R² is an alkyl radical with 4 to 8 carbon atoms and
n is a number from 7 to 12
mean as foam-suppressing additives in detergents.

However, these compounds show none below 20 to 25 ° C Anti-foam effect.

DE-OS 37 27 378 describes the use of alkyl polyethylene glycol ethers of the same general formula (Ia), with the same meaning the radicals R¹ and R², but with n = 2 to 6, as foam-suppressing Additives in cleaning agents. However, these connections show below 15 ° C no anti-foaming effect. The foam blanket (Foam height) when testing the anti-foam effect was at temperatures 15 ° C <1 cm. Because of their manufacture, ethoxylation of fatty alcohols in the presence of alkaline catalysts, already indicate those that have not yet been closed to end groups Alkyl polyethylene glycols have a broad homolog distribution on n on. This homolog distribution remains through the following The etherification reaction step remains unchanged. A foam effect however, the aim is at even lower temperatures. Furthermore show these additions in terms of packaging of the quantities which can be mixed into the formulations has the disadvantage of Phase separation that starts with small fractions.

The present invention was therefore based on the object of foam-suppressing Find substances, their application properties those of the prior art at temperatures are also superior below 15 ° C and at the same time the required possess biodegradability. Furthermore, should the additions regarding the assemblability the additions of the Exceed the state of the art.  

Surprisingly, it has now been found that alkyl polyethylene glycol ether, which has a narrow homolog distribution in terms of number of the (CH₂CH₂O) units contained in the molecule down to at temperatures of 5 ° C an even better foam inhibition and have a much better ability to assemble, which in larger possible packable quantities is expressed. A narrow homolog distribution was achieved using calcined hydrotalcites as catalysts in ethoxylation the fatty alcohols.

The invention therefore relates to the use of end group-capped Alkyl polyethylene glycol ethers of the formula

R¹-O- (CH₂CH₂O) _n -R² (I)

in the
R¹ is a straight-chain, branched or cyclic alkyl radical or alkenyl radical with 6 to 18 C atoms,
R² is an alkyl radical with 4 to 8 carbon atoms and
n is a number between 3 and 6
mean produced from ethylene oxide and a fatty alcohol or fatty alcohol mixtures containing R 1 and subsequent etherification with an alkyl halide containing R 2 by ethoxylation of the fatty alcohol in the presence of calcined hydrotalcites as a catalyst, as foam-suppressing additives for low-foaming cleaning agents.

Hydrotalcite is a natural mineral with the ideal formula

Mg₆Al₂ (OH) ₁₆CO₃ · 4 H₂O,

whose structure is derived from that of brucite (Mg (OH) ₂) is. Brucite crystallizes in a layer structure with the metal ions in octahedral gaps between two layers of tightly packed Hydroxyl ions, leaving only every second layer of the octahedral gaps is busy. There are some magnesium ions in hydrotalcite due to aluminum ions replaced, which makes the shift pack a positive charge receives. This is offset by the anions that are together with zeolitic crystal water in the intermediate layers are located. The layer structure becomes clear in the X-ray powder diagram (ASTM Card No. 14-191) used for characterization can be.

There are also synthetically produced hydrotalcites known e.g. B. in DE-PS 15 92 126, DE-OS 33 46 943, DE-OS 33 06 822 and EP-A 02 07 811 are described.

In natural and synthetic products, the Mg ²⁺ : Al ³⁺ ratio can vary between about 1 and 5. The ratio of OH ^- : CO₃ ^2- can fluctuate. Natural and synthetic hydrotalcites can be represented by the general formula (II)

Mg _x Al (OH) _y (CO₃) _z · H₂O (II)

are approximately described, the conditions 1 <x <5, y <z, (y + 0.5 z) = 2 x + 3 and 0 <m <10 apply. differences in the composition of the hydrotalcites, in particular with regard to the Water content, lead to line shifts in the X-ray diffraction diagram.

Natural or synthetic hydrotalcites give on heating or water continuously during calcination. The drainage is at  200 ° C completely, whereby it can be proven by X-ray diffraction could that the structure of hydrotalcite was still preserved is. The further increase in temperature leads to the elimination of Hydroxyl groups (as water) and carbon dioxide to break down the Structure. Natural and according to various methods, e.g. B. according the above publications, man-made hydrotalcites show generally similar behavior in the calcination.

As catalysts for polyalkoxylation, u. a. Calcium and strontium hydroxides, alkoxides and phenoxides (EP-A 00 92 256), calcium alkoxides (EP-A 00 91 146), barium hydroxide (EP- B 01 15 083), basic magnesium compounds, e.g. B. alkoxides (EP-A 00 82 569), magnesium and calcium fatty acid salts (EP-A 00 85 167) been used. The aforementioned catalysts have u. a. the Disadvantage that they are difficult to incorporate into the reaction system and / or are difficult to manufacture. Common polyalkoxylation catalysts are still potassium hydroxide and sodium methylate.

When using these catalysts, the fatty alcohols react in each case with several molecules of ethylene oxide.

It has now been found that using calcined hydrotalcites as catalysts fatty alcohols (R¹OH) with short reaction times can polyethoxylate with high yields and the reaction products obtained with a narrow range or homolog distribution can be, the distribution curve of the Poisson calculated comes very close.

All of the by calcination are suitable for the purposes of the invention from the natural and / or synthetic mentioned above Catalysts available from hydrotalcites. Are preferred  Hydrotalcites which, before calcination, have the general formula (II) with the above conditions for x, y, z and m. Values for x of 1.8 to 3 are particularly preferred.

The calcined hydrotalcites used according to the invention have continue to have the advantage of being in the reaction mixture of ethoxylation can be easily incorporated and because of their insolubility separated again in the reaction mixture by simple measures can be. However, they can also remain in the reaction mixture if their presence in the reuse of the reaction products does not bother.

Suitable fatty alcohols R¹OH are all alcohols with a straight-chain, branched or cyclic alkyl radical or alkenyl radical with 6 to 18 carbon atoms, especially n-hexanol, cyclohexanol, n- Octanol, n-nonanol, n-decanol, n-undecanol, n-dodecanol, n-tridecanol, n-tetradecanol, n-pentadecanol, n-hexadecanol, n-heptadecanol, n-octadecanol, n-octadec-9-en-1-ol (oleyl alcohol) and whose isomers branched on the alkyl radical and their isomers with OH Groups of internal carbon atoms and oxo alcohols of the above C atom number, individually or in a mixture. With the mixtures R¹OH are particularly important the C₁₂-C₁₄ and C₁₂-C₁₈ mixtures.

According to a further advantageous embodiment of the present According to the invention, the calcined hydrotalcites are used in an amount from 0.1 to 2% by weight, based on the end product of the ethoxylation, to the reaction mixtures.

The calcined hydrotalcites to be used can be obtained from the natural or synthetic hydrotalcites by heating for several hours  can be obtained at temperatures above 100 ° C. Especially calcination temperatures of 400 to 600 ° C. are preferred.

The catalyst thus obtained becomes the reaction mixture from one of the fatty alcohols and ethylene oxide described above, added. The molar ratio of fatty alcohol to ethylene oxide is preferably 1: 3.5 to 1: 5, particularly preferably 1: 4.5.

The etherification of the free hydroxyl groups is preferred among the known conditions of Williamson's ether synthesis with straight-chain or branched C₄-C₈ alkyl halides (R²X; X = Cl, Br, I) carried out, 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 can be useful Alkyl halide and alkali compound in stoichiometric excess, for example from 100 to 200%, over those to be etherified To use hydroxyl groups of the alkyl polyethylene glycol ethers.

The biodegradability of those to be used according to the invention End-capped alkyl polyethylene glycol ethers of the general Formula (I) corresponds to the legal determination methods RVO put to the detergent.

The end-capped alkyl polyethylene glycol ethers to be used according to the invention of the formula (I) are notable for their alkali and acid stability. When using the invention of the compounds of formula (I) is the anti-foaming effect at temperatures down to 5 ° C in alkaline to weak acidic cleaning liquors superior to the known foam inhibitors. The foam height is relatively low and is between 0 and 0.5 cm.  

The detergents containing the end-capped alkyl polyethylene glycol ethers (I) are used according to the invention, The components customary in such agents, such as wetting agents, Builders and complexing agents, alkalis or acids, Corrosion inhibitors and possibly also antimicrobial agents and / or contain organic solvents.

Non-ionic surface-active substances come as wetting agents, such as polyglycol ethers, which are caused by the addition of ethylene oxide to alcohols, in particular fatty alcohols, alkylphenols, fatty amines and carboxamides, are obtained, and anionic wetting agents, such as Alkali metal, amine and alkanolamine salts of fatty acids, alkyl sulfuric acids, Alkylsulfonic acids and alkylbenzenesulfonic acids in Consider. The cleaning agents can be used on framework substances and complexing agents especially alkali metal orthophosphates, polyphosphates, silicates, borates, carbonates, polyacrylates and gluconates and Citric acid, nitriloacetic acid, ethylenediaminetetraacetic acid, 1-hydroxyalkane-1,1-diphosphonic acid, aminotri- (methylenephosphonic acid) and ethylenediaminetetra- (methylenephosphonic acid), phosphonoalkane polycarboxylic acids, e.g. B. phosphonobutane tricarboxylic acid, and alkali metal salts and / or amine salts of these acids. Highly alkaline Cleaning agents, especially those for flange cleaning, contain considerable amounts of caustic potash in the form of sodium and potassium hydroxide. If special cleaning effects are desired cleaning agents can be organic solvents, for example alcohols, gasoline fractions and chlorinated Contain hydrocarbons and free alkanolamines.

Cleaning agents are used in connection with the invention on the one hand, for direct application to the substrates to be cleaned understood certain aqueous solutions; the term also includes "Cleaning agents" also those for the production of application solutions certain liquid concentrates and solid mixtures.  

The ready-to-use solutions can be slightly acidic to strongly alkaline be.

The use of the surfactants according to the invention in cleaning agents Due to process-technical conditions (control measurements, Material problems) in unheated or unheatable Industrial plants take place (J. Geke, Metallfläche 41 (1987), 227 ff).

The better packaging of the surfactants is expressed according to the Invention characterized in that in corresponding industrial cleaning Formulations a larger proportion of the respective mixed ethers Formula (I) compared to mixed ethers of the prior art good homogeneity without phase separation of the concentrates can be. This effect is extraordinary in terms of application technology important, firstly, that larger quantities are otherwise foaming Substances such as B. quaternary ammonium compounds (DE-OS 36 20 011, DE-PS 27 12 900), used and by the now possible, however the necessary higher dose of mixed ethers can also be foam-inhibited can and on the other hand for the fact that it is possible in the case of introduction foaming substances in the corresponding industrial cleaning baths to achieve a significantly more effective foam inhibition. That means a higher effectiveness per se with a temporary effect longer inhibition phase. Longer bath lifetimes are the result; the waste water volume is minimized.

The surfactants as described here are used in particular in industrial cleaners, either for the assembly of cold sprayable Industrial cleaners, or for industrial cleaners who are usually also cold sprayable, but for example with  quaternary ammonium compounds or other additional nonionic Tensides are made up with a higher cloud point, those without annoying foam when not using this mixed ether would not be sprayable.

The end-capped alkyl polyethylene glycol ethers to be used according to the invention are preferably in the cleaning agents added such amounts that their concentration in the ready-to-use Application solutions 10 to 2500 ppm, particularly preferred Is 50 to 500 ppm.

Figs. 1 to 4 show the curves of the gas chromatographic homolog distribution of various polyethylene glycol ethers which have been prepared with calcined hydrotalcites as catalyst, as compared with those prepared in the presence of sodium methoxide as a catalyst.

The invention is illustrated by the following examples, without being limited to it.

Examples I. Ethoxylation of fatty alcohols in the presence of calcined Hydrotalcite Example 1

A commercial synthetic hydrotalcite was at 500 ° C for 8 h calcined.  

For the implementation of a commercially available lauryl alcohol with 6 moles of ethylene oxide the lauryl alcohol was placed in a pressure reactor and with 0.5 wt .-%, based on the expected end product, of the previously obtained calcined hydrotalcite. The reactor was with Nitrogen purged and at a temperature of 100 ° C for 30 minutes evacuated. The temperature was then raised to 180 ° C and the desired amount of ethylene oxide at a pressure of 4 to 5 bar pressed. After the reaction had ended, the mixture was left to react for 30 minutes. After filtering off suspended catalyst was obtained the desired reaction mixture, the characteristics of which Table 1 can be seen.

Examples 2 to 5

Analogous to the manner described in Example 1, the in Table 1 listed fatty alcohols using calcined synthetic hydrotalcites reacted with ethylene oxide. The used Compounds, the amounts of ethylene oxide converted, the calcination conditions for hydrotalcites, the catalyst concentration, the reaction time of the ethoxylation and the OH numbers some of the ethoxylation products obtained are shown in Table 1 for some connections summarized. Furthermore, in Table 1 noted for some connections in which figure the achieved Homologous compounds are shown compared to sodium methylate are.

Calcined hydrotalcites were used in Examples 1 and 3, where the atomic ratio of Mg: Ca (corresponding to x in the general formula (II)) above was 2.17. For the calcined Hydrotalcite of Examples 2 and 4 was the Mg / Ca atomic ratio 2.17. Before etherification, especially butylation  the polyethylene glycol ether became the alkyl polyethylene glycol ether determined the homolog distribution by gas chromatography. The figures show the homolog distributions obtained according to the examples compared to those achievable when using sodium methylate.  

Table 1

Ethoxylation of fatty alcohols

II. Checking the antifoam effect

Surfactant A and B (Table 2) are comparative compounds whose alkyl polyethylene glycol ether precursors according to the conventional Processes with alkaline catalysts were made (DE-OS 37 27 378) and have a broad homolog distribution. The alkyl polyethylene glycol ether precursors of surfactants C and D was in the presence of calcined hydrotalcites as a catalyst produced. n gives the maximum of the respective homolog of the homolog distribution again. The test of the anti-foam effect was in a practical 10 l continuous spray system at one spray pressure from 3 to 10 bar (30 mm smooth jet nozzle). The circulation volume amounted to approx. 10 to 19 l / min.

In the following examples, the operating temperatures specified in each case were: as application technology sprayable with minimal Foam exposure denotes the cleaning solutions that are in continuous use with otherwise fast foam disintegration, practically no foam blanket (0 to 0.5 cm).

The connections used in detail are as follows Table 2 shows.

Table 2

Example 6

400 ppm surfactant C or D:

With an aqueous solution of this surfactant, iron and steel sheets were made treated at 5 ° C. With a good cleaning effect, none disturbing foam development observed. The application solution is foam-free sprayable.

Comparative Example 1

400 ppm surfactant A:

Below 15 ° C <1 cm foam development (foam blanket) was observed.

Comparative Example 2

400 ppm surfactant B:

Foam-free sprayability only at temperatures <15 ° C.

Example 7

2500 ppm diethanolamine salt of isononanoic acid,
2000 ppm diethanolamine,
100 ppm benzotriazole,
400 ppm surfactant C or D:

With an aqueous solution of this cleaner (pH 9) iron and Treated steel sheets. With a good cleaning effect at 5 ° C no disturbing foam development observed.  

Comparative Example 3

When adding 400 ppm of surfactant A instead of surfactant C or D in the The above composition did not become a nuisance when the cleaning effect was good Foam development only up to a temperature of 15 ° C observed.

Example 8

3000 ppm sodium caprylate,
1000 ppm sodium tetraborate · 10 H₂O (borax),
1400 ppm sodium tripolyphosphate,
1000 ppm triethanolamine,
200 ppm monoethanolamine
600 ppm surfactant C or D:

With an aqueous solution of this cleaner (pH 9) iron and Steel sheets treated at 5 ° C. With a good cleaning effect no disturbing foam development.

Comparative Example 4

When using 600 ppm surfactant B instead of surfactant C or D in The above formulation only had a good cleaning effect observed up to a temperature of 15 ° C.

Example 9

2500 ppm sodium dihydrogen phosphate,
2100 ppm disodium hydrogen phosphate,
1000 ppm tartaric acid,
500 ppm phosphoric acid, 75%,
400 ppm surfactant C or D:

With an aqueous solution of this cleaner (pH 3.5) iron sheets treated at 5 ° C. With a good cleaning effect, none disturbing foam development observed.

Comparative Example 5

When using 400 ppm of surfactant A instead of surfactant C or D in the above composition was only with good cleaning effect up to 15 ° C no disturbing foam development was observed.

III. Ready to assemble

Basis 1 and 2 provide examples of detergent formulations to which the surfactants C or D according to the invention have been added. The comparison is made with formulations containing the comparative surfactant A contained.

Basis 1:

58 parts by weight of water
10 parts by weight of monoethanolamine
20 parts by weight of triethanolamine
2 parts by weight of carboxylic acid, 8 carbon atoms
10 parts by weight of branched carboxylic acid

Basis 2:

60 parts by weight of water
20 parts by weight of diethanolamine
20 parts by weight of branched carboxylic acid

Table 3

Claims (8)

1. Use of end-capped alkyl polyethylene glycol ethers of the formula R¹-O- (CH₂CH₂O) _n -R² (I) in the
R¹ is a straight-chain, branched or cyclic alkyl radical or alkenyl radical with 6 to 18 C atoms,
R² is an alkyl radical with 4 to 8 carbon atoms and
n is a number between 3 and 6
mean produced from ethylene oxide and a fatty alcohol or fatty alcohol mixtures containing R 1 and subsequent etherification with an alkyl halide containing R 2 by ethoxylation of the fatty alcohol in the presence of calcined hydrotalcites as a catalyst, as foam-suppressing additives for low-foaming cleaning agents. 2. Use according to claim 1, characterized in that the hydrotalcites have a composition of formula (II) Mg _x Al (OH) _y (CO₃) _z · m H₂O (II) in which the conditions 1 <x < 5, y <z, (y + 0.5 z) = 2 x + 3 and 0 <m <10 apply. 3. Use according to claims 1 and 2, characterized in that for the hydrotalcites of the general formula (II) x a number of 1.8 to 3 and y, z and m are as defined above.   4. Use according to claims 1 to 3, characterized in that calcined the hydrotalcites at temperatures between 400 and 600 ° C were. 5. Use according to claims 1 to 4, characterized in that the calcined hydrotalcites in an amount of 0.1 to 2 wt .-%, based on the end product of the ethoxylation. 6. Use according to claims 1 to 5, characterized in that in formula (I) n is 3.5 to 5, preferably 4.5. 7. Use according to claims 1 to 6, characterized in that in the formula (I) R² = n-butyl and R¹ = octyl, decyl or dodecyl is. 8. Use according to claims 1 to 7, characterized in that the end-capped alkyl polyethylene glycol ethers in such Amounts are used that their concentration in the ready-to-use Solutions 10 to 2500 ppm, preferably 50 to 500 ppm, is.