EP0506751B1 - Use of a combination of non-ionic surface-active agents - Google Patents

Abstract

The invention concerns the use, for cleaning hard surfaces, of a combination of non-ionic surface-active agents, the combination containing: (a) at least one alk(en)yl ethoxylate of general formula (I): R<1>-O-(CH2CH2O)n-H, in which R<1> is a straight-chain or branched-chain alkyl or alkenyl group with 6-18 C-atoms or a cyclic alkyl group with 5-6 C-atoms, and n is a number in the range from 2 to 12, and (b) at least one alk(en)yl ethoxylate propoxylate of general formula (II): R<2>-O-(CH2CH2O)p-A-H, in which R<2> is a straight-chain or branched-chain alkyl or alkenyl group with 6-18 C-atoms or a cyclic alkyl group with 5-6 C-atoms, p is a number in the range 2 to 10 and A is a group of the type -(CH2-CH(CH3)-O)q- or -(CH(CH3)-CH2-O)r-, the sum q + r being a number in the range from 2 to 8, the ratio by weight of components a and b being in the range from 10:1 to 1:10.

Description

The present invention relates to the use of a combination of nonionic surfactants - optionally with conventional additives - for cleaning hard surfaces in the spraying process. So-called "industrial cleaners" are usually used for such tasks.

Industrial cleaners of this type are mainly used in the automotive industry and their supplier industries for cleaning and passivation, primarily in spray cleaning systems. They are suitable for intermediate and final cleaning without cutting as well as machined parts in unit and assembly plants. Practically all relevant materials, such as iron and steel, aluminum, silumen, copper, brass, zinc and plastics, can be treated and the majority of all contaminations on an organic or inorganic basis, such as cooling lubricants, rust protection oils, processing oils, drawing aids, pigments and light metal abrasion, can be removed. Such cleaning agents can also be used in customary immersion processes, but their use in the spraying process is usually preferred.

The chemical basic components of such industrial cleaners are usually surfactants and organic corrosion inhibitors. The latter ensure temporary protection against corrosion during and after treatment. In addition, cleaning agents of this type generally contain substances which are capable of an undesirable one Counteract foam development. The use of such foam-inhibiting additives is in most cases due to the fact that the contaminants detached from the substrates and accumulating in the cleaning baths act as foaming agents. In addition, the use of so-called anti-foaming agents may also be necessary due to the fact that the cleaning agents themselves contain constituents which give rise to undesirable foaming under the given working conditions - ie in particular in the case of spraying processes, for example anionic surfactants or nonionic surfactants foaming at the respective working temperature.

From "Ullmann's Encyclopedia of Industrial Chemistry", 4th edition, volume 22 (1982), pages 489 to 493, the use of fatty alcohol polyethylene glycol ethers - also called fatty alcohol ethoxylates - as surfactant components in detergents and cleaning agents is known. However, such addition products of ethylene oxide with fatty alcohols are not suitable for use in spraying processes, since they foam strongly at application temperatures in the range from 15 to 80.degree. It is also known to use fatty alcohol ethoxylate propoxylates as low-foaming wash raw materials; see. for example the Ullmann volume cited above, page 494.

• (A) 2 bis 35 Gew. -% C₈₋₂₂-Fettalkohol-polyethylenglykolether mit 5 bis 25 Alkylenoxid-Einheiten,
• (B) 5 bis 35 Gew.-% Alkanolamin,
• (C) 0,5 bis 6 Gew.-% eines Sequestriermittels und
• (D) 0,5 bis 5 Gew.-% eines biologisch abbaubaren, schwach schäumenden nichtionischen Tensids der Formel R-O-(CH₂CH₂O)_x-(CH₂-C(R₁)HO)_y-H, worin R einen C₈₋₂₂-Alkylrest, R₁ Methyl oder Ethyl, x eine Zahl von 1 bis 12 und y eine Zahl von 1 bis 5 bedeuten und das Verhältnis von x : y im Bereich von 3 : 1 bis 1 : 3 liegt.

GB-A-2 204 321 relates to biodegradable, low-foaming cleaning agents based on aqueous solutions which contain the following components:

• (A) 2 to 35% by weight of C₈₋₂₂ fatty alcohol polyethylene glycol ether with 5 to 25 alkylene oxide units,
• (B) 5 to 35% by weight alkanolamine,
• (C) 0.5 to 6% by weight of a sequestering agent and
• (D) 0.5 to 5 wt .-% of a biodegradable, low-foaming nonionic surfactant of the formula RO- (CH₂CH₂O) _x - (CH₂-C (R₁) HO) _y -H, wherein R is a C₈₋₂₂-alkyl radical , R₁ is methyl or ethyl, x is a number from 1 to 12 and y is a number from 1 to 5 and the ratio of x: y is in the range from 3: 1 to 1: 3.

Such formulations can be used both for cleaning hard surfaces and for washing textiles.

• (A) 20 bis 80 Gew.-% Polyethylenglykolether der Formel R₁-O-(CH₂CH₂O)_n-R₂, worin R₁ einen geradkettigen oder verzweigten Alkylrest oder Alkenylrest mit 8 bis 18 C-Atomen, R₂ einen Alkylrest mit 4 bis 8 C-Atomen und n eine Zahl von 3 bis 7 bedeuten,
• (B) 10 bis 40 Gew.-% Alkylpolyalkylenglykol-Mischether der Formel R₃-O-(CH₂CH₂O)_x-(CH₂-C(CH₃)HO)_y-H worin R₃ einen geradkettigen oder verzweigten Alkylrest mit 8 bis 18 C-Atomen, x eine Zahl von 1 bis 3 und y eine Zahl von 3 bis 6 bedeuten, sowie
• (C) 0 bis 40 Gew.-% Alkyl-(poly)-propylenglykolether der Formel R₄-O-(CH₂-C(CH₃)HO)_z-H, in der R₄ einen geradkettigen oder verzweigten Alkyl- oder Alkenylrest mit 16 bis 22 C-Atomen und z eine Zahl von 1 bis 3 bedeuten.

Furthermore, EP-A-0 254 208 describes low-foam or foam-suppressing surfactant mixtures which contain the following components:

• (A) 20 to 80% by weight of polyethylene glycol ether of the formula R₁-O- (CH₂CH₂O) _n -R₂, where 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 C- Atoms and n represent a number from 3 to 7,
• (B) 10 to 40 wt .-% alkyl polyalkylene glycol mixed ether of the formula R₃-O- (CH₂CH₂O) _x - (CH₂-C (CH₃) HO) _y -H wherein R₃ is a straight-chain or branched alkyl radical having 8 to 18 carbon atoms , x is a number from 1 to 3 and y is a number from 3 to 6, and
• (C) 0 to 40 wt .-% alkyl (poly) propylene glycol ether of the formula R₄-O- (CH₂-C (CH₃) HO) _z -H, in which R₄ is a straight-chain or branched alkyl or alkenyl radical with 16 to 22 carbon atoms and z represent a number from 1 to 3.

Such surfactant mixtures are used in aqueous cleaning agents for cleaning hard surfaces, in particular also for spray cleaning at temperatures below 50 ° C.

In contrast, the object of the present invention was to provide surfactant combinations for cleaning hard surfaces which have low-foaming properties in the entire temperature range relevant to the application, namely in the range from 15 to 80 ° C., and are therefore suitable for use in the spraying process. In addition, these surfactant combinations should have a high cleaning ability and excellent wetting properties compared to the substrates treated with them; further should these surfactant combinations can be easily assembled with additives common in industrial cleaners, allow the cleaning agent solutions to run off the treated substrate surfaces without stains and have demulsifying properties with regard to non-self-emulsifying oils and fats.

Surprisingly, it has been found that mixtures of the nonionic surfactants listed below fully meet the requirements described in the above task over a wide range of mixtures.

• (a) mindestens ein Alk(en)yl-ethoxylat der allgemeinen Formel (I)
  
          R¹-O-(CH₂CH₂O)_n-H   (I)
  
  in der R¹ einen linearen oder verzweigten Alkylrest oder Alkenylrest mit 6 bis 18 C-Atomen und n eine Zahl im Bereich von 2 bis 4 bedeuten,
  oder
  in der R¹ einen linearen Alkylrest mit 6 C-Atomen und n die Zahl 6 bedeutet,
  und
• (b) mindestens ein Alk(en)yl-ethoxylatpropoxylat der allgemeinen Formel (II)
  
          R²-O-(CH₂CH₂O)_p-A-H   (II)
  
  in der R² einen linearen oder verzweigten Alkylrest oder Alkenylrest mit 6 bis 18 C-Atomen oder einen cyclischen Alkylrest mit 5 bis 6 C-Atomen, p eine Zahl im Bereich von 2 bis 10 und A Reste vom Typ -(CH₂-CH(CH₃)-O)_q- und -(CH(CH₃)-CH₂-O)_r- bedeuten, wobei die Summe (q + r) eine Zahl im Bereich von 2 bis 8 ist,
  wobei das Gewichtsverhältnis der Komponenten a : b im Bereich von 10 : 1 bis 1 : 10 liegt.

The present invention thus relates to the use of a combination of nonionic surfactants based of alk (en) yl ethoxylates and alk (en) yl ethoxylate propoxylates for cleaning hard surfaces by spraying, characterized in that they contain the following components:

• (a) at least one alk (en) yl ethoxylate of the general formula (I)
  
  R¹-O- (CH₂CH₂O) _n -H (I)
  
  in which R¹ is a linear or branched alkyl radical or alkenyl radical having 6 to 18 carbon atoms and n is a number in the range from 2 to 4,
  or
  in which R¹ is a linear alkyl radical with 6 carbon atoms and n is 6,
  and
• (b) at least one alk (en) yl ethoxylate propoxylate of the general formula (II)
  
  R²-O- (CH₂CH₂O) _p -AH (II)
  
  in which R² is a linear or branched alkyl radical or alkenyl radical having 6 to 18 carbon atoms or a cyclic alkyl radical having 5 to 6 carbon atoms, p is a number in the range from 2 to 10 and A radicals of the type - (CH₂-CH (CH₃ ) -O) _q - and - (CH (CH₃) -CH₂-O) _r - mean where the sum (q + r) is a number in the range from 2 to 8,
  wherein the weight ratio of components a: b is in the range from 10: 1 to 1:10.

With regard to the surfactant components a and b to be used according to the invention, the following applies in detail:

In the general formula (I) of components a mentioned above, R 1 represents a linear or branched alkyl radical or alkenyl radical having 6 to 18 carbon atoms. The following radicals are therefore suitable as substituent R 1: n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl , n-hexadecyl, n-heptadecyl and n-octadecyl and the branched chain isomers of the alkyl radicals mentioned. Instead of the saturated alkyl radicals, R 1 can also mean the unsaturated alkyl radicals (alkenyl radicals) with a number of carbon atoms in the above range, which can likewise be linear or branched.

For the purposes of the invention, preference is given to using, as component a, those compounds of the general formula (I) in which R 1 is a linear alkyl radical or alkenyl radical having 6 to 18 carbon atoms. According to a particularly preferred embodiment of the present invention, the reaction product of octanol (R 1 = linear alkyl radical having 8 carbon atoms) with 4 moles of ethylene oxide is used as the surfactant component a.

For the preparation of compounds of the general formula (I), reference is made, for example, to the Ullmann monograph cited above. Such products are also commercially available, for example under the brand name DEHYDOL ^R (Henkel KGaA, Düsseldorf).

In the above-mentioned general formula (II) of the surfactant components b, R 2 represents a linear or branched alkyl radical or alkenyl radical with 6 to 18 carbon atoms or a cyclic alkyl radical with 5 to 6 carbon atoms. Suitable substituents R 2 are therefore all those radicals which have already been explained above in connection with the substituent R 1 of the general formula (I). The number of ethoxy radicals in the molecule - index p - is in the range from 2 to 10. The substituent A in the general formula (II) stands for propoxy radicals, the number of propoxy radicals - index (q + r) - in the range from 2 to 8 lies.

For the purposes of the invention, components b of the general formula (II) are preferably used as component b in which R 2 is a linear alkyl radical having 8 to 18 carbon atoms, p is a number in the range from 2 to 5 and A is propoxy radicals, and the sum (q + r) is a number in the range 4 to 6. According to a particularly preferred embodiment of the present invention, the reaction product of technical lauryl alcohol - which has alkyl radicals with 12 to 18 carbon atoms (thereof about 80% with 12 to 14 carbon atoms) - with 2 to 4 is used as the surfactant component b Moles of ethylene oxide and 4 to 6 moles of propylene oxide or the reaction product of n-octanol with 2 to 6 moles of ethylene oxide and 2 to 5 moles of propylene oxide.

For the preparation of compounds of the general formula (II), reference is also made, for example, to the Ullmann monography cited above. Such products are also commercially available, for example under the brand name DEHYPON ^R -LS or -LT (Henkel KGaA, Düsseldorf).

Depending on the area of use and intended use, further nonionic surfactants can be added to the surfactant combinations to be used according to the invention. According to a further preferred embodiment of the present invention, the surfactant combinations to be used according to the invention contain, as additional component c, at least one alk (en) yl ethoxylate mixed ether of the general formula (III)

R³-O- (CH₂CH₂O) _s -R⁴ (III)


in which R³ is a linear or branched alkyl radical or alkenyl radical with 6 to 18 carbon atoms or a cyclic alkyl radical with 5 to 6 carbon atoms, s is a number in the range from 2 to 12 and R⁴ is a linear or branched alkyl radical with 1 to 8 carbon atoms -Atoms mean, the weight ratio of components (a + b): c being in the range from 1: (0.1 to 4).

In the general formula (III) of the surfactant components c given above, R³ therefore stands for a linear or branched alkyl radical or alkenyl radical with 6 to 18 carbon atoms or a cyclic alkyl radical with 5 to 6 carbon atoms. Suitable substituents R³ are therefore all those radicals which have already been explained above in connection with the substituent R¹ of the general formula (I). The number of ethoxy radicals in the molecule - index s - is here in the range from 2 to 12. The substituent R⁴ in the general formula (III) stands for a linear or branched alkyl radical with 1 to 8 C atoms; thus for methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl and for the corresponding branched-chain isomers. Such alk (en) yl ethoxylate mixed ethers, which are also referred to as end group-capped fatty alcohol polyethylene glycol ethers are described in more detail in DE-A-33 15 951, 37 27 378 and 38 00 490. The production of these nonionic surfactants is also disclosed in detail in these German published publications.

For the purposes of the invention, it is preferred to use at least one alkyl ethoxylate mixed ether of the general formula (III) as additional component c of the surfactant combination, where R 3 is a linear alkyl radical having 8 to 10 carbon atoms, s is a number in the range from 3 to 5 and R⁴ represent an n-butyl radical. Particularly preferred mixed alkyl ethoxylate ethers of the general formula (III) are addition products of 3.5 to 4.5 mol of ethylene oxide onto fatty alcohols having 8 to 10 carbon atoms and etherified with an n-butyl radical.

The surfactant combinations to be used according to the invention are further characterized by a certain weight ratio of components a: b, which is generally in the range from 10: 1 to 1:10. If only these two components are used in the manner according to the invention, the preferred weight ratio of components a: b is in the range from 2: 1 to 1: 2. However, if the surfactant combination to be used according to the invention contains the additional component c, the weight ratio is of components (a + b): c in the range from 1: 0.1 to 1: 4, preferably in the range from 1: 0.1 to 1: 1.5.

The surfactant combinations to be used according to the invention are notable for high cleaning power at temperatures in the range from 15 to 80 ° C. They are in the temperature range mentioned can also be used without any problems in the spraying process since they do not cause any undesirable foam development. Further advantages are: very good wetting properties, very good demulsifying properties with regard to non-self-emulsifying oils and fats as well as easy assembly with additives commonly used in industrial cleaners.

Possible additives which are preferably used in addition to the surfactant combinations to be used according to the invention are: builder substances and / or complexing agents, corrosion inhibitors and bases or acids. Optionally, stabilizers, solubilizers or antimicrobial agents can also be used as additives.

As builders and / or complexing agents, for example, alkali metal orthophosphates, polyphosphates, silicates, borates, carbonates, polyacrylates and gluconates can be used, as well as phosphonic acids or phosphonoalkane carboxylic acids or their water-soluble alkali metal salts, for example 1-hydroxyethane-1,1-diphosphate or 2-phosphonobutane-1,2,4-tricarboxylic acid. Straight-chain or branched aliphatic carboxylic acids or their salts are suitable as effective corrosion inhibitors. In particular, alkanolamine salts of straight-chain or branched monocarboxylic acids with 8 to 11 carbon atoms are used as corrosion inhibitors. Depending on the intended use, the aqueous solutions of the surfactant combinations to be used according to the invention can be acidic or also alkaline; accordingly, they contain excess acid or bases, for example sodium hydroxide and / or potassium hydroxide.

The surfactant combinations to be used according to the invention are produced by simply mixing the individual components. Corresponding powdery or liquid cleaning agents are also produced in the same way by mixing the surfactant combinations to be used according to the invention with the other additives and, if appropriate, water. For the purposes of the invention, cleaning agents of this type contain 1 to 70% by weight, preferably 2 to 20% by weight, of the surfactant combinations to be used according to the invention.

For the purposes of the invention, the surfactant combinations to be used according to the invention are preferably used in the form of application solutions diluted with water. Such application solutions preferably contain the surfactant combinations to be used according to the invention in concentrations of 0.0001 to 1.5% by weight, in particular 0.0005 to 0.5% by weight. Ready-to-use solutions of this type, which are used in the sense of the invention for cleaning hard surfaces in the spray process, can likewise be strongly acidic to strongly alkaline (pH values in the range from 1 to 14) and preferably have pH values in the range from 3.5 to 11 on. Such application solutions are prepared by simply mixing the surfactant combinations with water.

The invention is illustrated by the examples below.

example 1

Surfactant combinations according to the invention

The abbreviations used below have the following meanings: EO = ethylene oxide, PO = propylene oxide

Example 2

Detergent basics,
as additives to the surfactant combinations according to the invention

basis 1:

55.3 parts

water

7.0 parts

Ethanolamine

10.0 parts

Triethanolamine

8.0 parts

Diethanolamine

15.0 parts

C₉-carboxylic acid, branched

1.0 parts

2-phosphonobutane-1,2,4-tricarboxylic acid

0.2 parts

Tolyltriazole

3.5 parts

Pentapotassium triphosphate

basis 2:

59.2 parts

water

10.0 parts

Ethanolamine

10.0 parts

Triethanolamine

5.0 parts

Diisopropanolamine

5.0 parts

n-octanoic acid

2.0 parts

C₉-carboxylic acid, branched,

5.0 parts

C₈-carboxylic acid, branched

3.0 parts

Boric acid

0.8 parts

Polyacrylate (MG ca.1500)

Basis 3:

Part 1

Disodium tetraborate x 10 H₂O

Part 1

Tetrasodium diphosphate x 10 H₂O

Basis 4:

72.3 parts

water

9.0 parts

Potassium hydroxide

2.5 parts

Sodium hydroxide

5.0 parts

Pentapotassium triphosphate

5.0 parts

Potassium gluconate

5.0 parts

Mixture of branched carboxylic acids with 9 to 11 carbon atoms (versatic acid, Shell)

1.2 parts

1-hydroxyethane-1,1-diphosphonic acid

Basis 5:

80.0 parts

water

15.0 parts

o-phosphoric acid

5.0 parts

Sodium hydroxide

basis 6:

Part 1

Pentasodium triphosphate

Part 1

Tetrasodium diphosphate

Part 1

Trisodium phosphate x 12 H₂O

Example 3

The application properties of the surfactant combinations to be used according to the invention according to Example 1 were tested in the detergent basics according to Example 2 in a laboratory spraying system. In this test, steel sheets (quality St 37), which were contaminated with corrosion protection oil, were mixed with aqueous application solutions, which are characterized in more detail in Table 1 below, treated by spraying (spray pressure 2.5 to 5 bar). The cleaning effect, the foaming behavior and the wetting of the sheet metal surfaces and the runoff behavior of the application solutions from the sheet metal surfaces were assessed visually.

In all cases of the individual examples summarized in Table 1, the tested application solutions showed a good cleaning effect. Furthermore, it was found that the application solutions used were readily sprayable at the temperatures given in Table 1 and showed no disruptive foam developments. The results obtained with regard to "wetting" and "run-off behavior" are each shown in Table 1 in the "Comments" column.

The individual columns in Table 1 are explained below:

"Basis":
Indication of the number of the detergent base used in the respective example according to example 2.

"Surfactant combination":
Indication of the designation (No.) of the surfactant combination used in the respective example according to Example 1;

"Proportion": means the respective concentration of the surfactant combination based on the detergent base in% by weight.

"Concentration":
Concentration of the detergent in the application solution in g / l.

"Water quality":
Quality of the water used to prepare the application solutions in terms of water hardness; it mean:
VEW = demineralized water
DIN = water hardness 20 ° d
BW = process water, hardness approx. 16 ° d.

"Spray temperature":
Temperature of the application solution when used in the spray process, without annoying foaming.

In the case of example 3.6, aluminum sheets were additionally treated. No undesirable discoloration of the aluminum surface was observed.

Comparative example

In comparative experiments, component a of the surfactant combination to be used according to the invention - octanol + 4 EO - was tested alone in a test according to Example 3. This surfactant was used here in a concentration of 1% by weight in the detergent bases given in Table 1 at spray temperatures between 20 and 70 ° C and a spray pressure of 3 bar - water quality: VEW.

In all cases there was a very strong, disruptive foam development.

Claims (6)

1. The use of a combination of nonionic surfactants based on alk(en)yl ethoxylates and alk(en)yl ethoxylate propoxylates for the spray cleaning of hard surfaces, characterized in that it contains the following components:

   (a) at least one alk(en)yl ethoxylate corresponding to general formula (I):
   
           R¹-O-(CH₂CH₂O)_n-H   (I)
   
   in which R¹ is a linear or branched alkyl radical or alkenyl radical containing 6 to 18 carbon atoms and n is a number of 2 to 4 or in which R¹ is a linear alkyl radical containing 6 carbon atoms and n is the number 6,
   and

   (b) at least one alk(en)yl ethoxylate propoxylate corresponding to general formula (II):
   
           R²-O-(CH₂CH₂O)_p-A-H   (II)
   
   in which R² is a linear or branched alkyl radical or alkenyl radical containing 6 to 18 carbon atoms or a cyclic alkyl radical containing 5 to 6 carbon atoms, p is a number of 2 to 10 and A represents units of the type -(CH₂-CH(CH₃)-O)_q- and -(CH(CH₃)-CH₂-O)_r- where the sum (q + r) is a number of 2 to 8, the ratio by weight of component a to component b being in the range from 10:1 to 1:10.
2. The use claimed in claim 1, characterized in that at least one alkyl ethoxylate propoxylate corresponding to general formula (II), in which R² is a linear alkyl radical containing 8 to 18 carbon atoms, p is a number of 2 to 5 and A is as defined above, the sum (q + r) being a number of 4 to 6, is used as component b of the surfactant combination.
3. The use claimed in claim 1 or 2, characterized in that the surfactant component contains at least one alk(en)yl ethoxylate mixed ether corresponding to general formula (III):
   
           R³-O-(CH₂CH₂O)_s-R⁴   (III)
   
   in which R³ is a linear or branched alkyl radical or alkenyl radical containing 6 to 18 carbon atoms or a cyclic alkyl radical containing 5 to 6 carbon atoms, s is a number of 2 to 12 and R⁴ is a linear or branched alkyl radical containing 1 to 8 carbon atoms, the ratio by weight of components (a + b) to component c being of the order of 1:(0.1 to 4),
   as an additional component c.
4. The use claimed in claim 3, characterized in that at least one alkyl ethoxylate mixed ether corresponding to general formula (III), in which R³ is a linear alkyl radical containing 8 to 10 carbon atoms, s is a number of 3 to 5 and R⁴ is an n-butyl radical, is used as the additional component c of the surfactant combination.
5. The use claimed in any of claims 1 to 4, characterized in that the surfactant combination additionally contains builders and/or complexing agents, corrosion inhibitors and bases or acids.
6. The use claimed in any of claims 1 to 5, characterized in that the surfactant combination is used in solutions diluted with water in concentrations of 0.0001 to 1.5% by weight and preferably in concentrations of 0.0005 to 0.5% by weight.