FI112246B - Polymer-thickened deicing agent and antifreeze for aircraft - Google Patents

Description

112246

Polymer-thickened deicing agent and antifreeze for aircraft

The invention relates to a de-icing and antifreeze agent for aircraft, based on glycols and water and containing water-soluble cross-linked acrylic polymers as a thickening agent.

De-icing and anti-icing agents for aircraft (hereinafter simply referred to as de-icing agents or de-icing fluids for short reasons) are used to remove ice, snow and / or frost on certain aircraft surfaces and to prevent such deposits on these surfaces. The time during which the de-icing fluid provides protection against the formation of ice, snow and / or frost on 15 aircraft is called the anti-icing time or is called "holdovertime". The "Recommendations for the De- / Anti-Icing of Aircraft on the Ground" published by the Association of European Airlines (March 1993) and the ISO (International Standardization Organization) Publications Spezifikationen 11075, 11075 and 11078 define two aircraft de-icing fluid type. Type I; * The liquids consist essentially of glycol, water, and corrosion inhibitors, and optionally tensides and pH-I 'regulators, and type II liquids additionally contain a water-soluble polymer as a thickener: to provide a high viscosity pseudoplastic consistency.

Type II aircraft de-icing agents; in particular, they are expected to provide long-lasting decks • against freezing of planes prior to departure in extreme weather conditions such as snowfall or freezing I '· * * and good outflow from hull carrying levels at the departure of the aircraft. ISO Standard 11078, effective in 1993, requires a period of protection of at least 35 minutes at -5 ° C for a period of protection of at least 35 minutes at the so-called "Water Spray Endurance Test" (residual 112246 2 fluids pre-set for 5 minutes). shear stress at 3500 rpm). The outflow behavior is described for the first time in ISO 11078 in a laboratory test, the so-called "Aerodynamic Acceptance Test", which sets the value of the Boundary Layer Displacement Thickness (d *) at a maximum temperature of -30 mm after a simulated output. ° C and 9.5 mm at -10 ° C.

The value of holdovertime-10 and the outflow behavior of the Type II antifreeze are crucially influenced by the thickener. The discovery of a good polymeric thickener is hampered, inter alia, by the fact that the two properties, holovertime and effluent behavior, are substantially opposite to one another.

Polymer-thickened aircraft de-icing agents are described, for example, in DE-A-2 423 893 (Derwent Ref. AN 83335W) and EP-B-0 050 700 (US-A-4 358 389), EP-B-0 231 869 ( US-A-4 744 913) and EP-B-0 360 183. They consist essentially of 20 a) 35 to 70 weight percent of at least one glycol selected from the group consisting of 2-3 C atoms. · 'Alkylene glycols and oxalkylene glycols having 4 to 6 carbon atoms,' * · b) from 0.05 to 1.5% by weight of at least one water C ': 25 soluble cross-linked copolymers as a thickener, c) 0.02 - 1.5% by weight of at least one

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d) at least one corrosive inhibitor in an effective amount; 30 e) at least one basic compound which is T for alkali metal carbonates, alkali metal hydroxides and • '·. a group of amines for adjusting the pH between 7 and 11; and: f) water added as a supplement to 100 wt.%, the values being in weight percent relative to the (final) 35 deicing agent.

112246 3

The de-icing and anti-freeze agent described in DE-A-2 423 893 contains as a thickener a water-soluble crosslinked or non-crosslinked acrylic or methacrylic acid homo- or copolymerate 5, wherein the comonomer may be present in an amount of 5 to 70 mol% ). Comonomers include the methyl, ethyl or butyl esters of acrylic, methacrylic or maleic acid, vinyl acetate, styrene, lower olefins, and acrylic or methacrylamides. EP-B-0 360 183 recommends water-soluble cross-linked polyacrylic acid products and EP-B-0 050 700 additionally water-soluble cross-linked copolymers of acrylic acid or methacrylic acid with 2 to 50% by weight of comonomer. 15 m); nothing else is mentioned about the quality of the comonomer. EP-B-0 231 869 uses as a thickener a mixture consisting essentially of a water-soluble crosslinked acrylic acid homopolymer and a copolymer of acrylic acid and acrylamide. The known thick-20 lubricants described give aircraft de-icers a certain pseudoplastic behavior, i.e. a relatively high viscosity (resting viscosity, referred to as yield value or "yield value"), which decreases with the shear limit. In this way, a good holdo-vertime value and at the same time sufficient outflow behavior are achieved. However, the specifications of ISO 11078 are so far-reaching that the thickeners described either provide only a sufficient therapeutic value (due to high resting viscosity) but do not meet the outflow behavior requirements, or provide only sufficient outflow behavior (low the prescribed resting viscosity

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' «. as a result), but then do not meet the holdovertime: requirements. The known polymeric · · * (thickeners, therefore, cannot simultaneously) * ..! 35 "Water Spray Endurance Time" test as defined in ISO 11078, and likewise the ISO 11078 reaffirmed value of 112246 4 "Boundary Layer Displacement Thickness "in the" Aerodynamic Acceptance Test ".

Also known in the art is the recent publication WO 93/24 543, which describes straight-chain or cross-linked polycarboxylates containing special macromonomers-5 as type 2 thickening agents for aircraft de-icing agents. The macromonomer contains a hydrophobic end group from the group of alkaryls and is attached via a bond ring to a polycarboxylate (polyacrylate, poly-10 methacrylate, etc.) (compare, for example, pages 9 and 19). This polymer thickener therefore requires relatively complex structured monomers and can only be prepared by several reaction steps.

As mentioned above, the two properties, holdovertime and outflow behavior, are opposite to each other. In order to obtain sufficient effluent behavior, the viscosity and hence the concentration of the thickener must be chosen as low as possible. A sufficient holovertime value, on the other hand, requires a maximum yield strength of 20 degrees of de-icing agent and thus a generally high viscosity and high thickener content.

It is therefore an object of the invention to find a simple construction and easy-to-make package, a propellant polymer that provides increased pseudoplasticity or increased viscosity in shear stress due to high shear stress in the finished aircraft de-icing agent. the resting viscosity becomes clearly faster to sensitive motion and thus flows away better. New *..! 3 0 de-icing agent with elevated pseudoplasticity will meet the Water Spray Endurance Test for its • • high high dewatering viscosity and achieve: the low required simultaneously in the aerodynamic duct or outlet due to faster drainage

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35 Layer Displacement Thickness "values in" Aerodynamic * ·

Acceptance Test ". The new Type II aircraft antifreeze will therefore be based on a simple and readily available polymeric thickener and will largely meet the requirements of ISO 11078 for holdovertime and outflow behavior.

It has now been found that for water-soluble crosslinked polymers containing acrylic acid or methacrylic acid as the main monomer and an ester of acrylic acid or methacrylic acid as the second monomer, the ester group having a long alkyl group and one or two long alkyl groups having 10 type II antifreeze agents having the combination of properties required above.

According to the invention, the proposed thickener is a ve-15 silicified crosslinked copolymer comprising 85 to 99% by weight of polymerized units of acrylic acid or methacrylic acid and 1 to 15% by weight of an ester or amide of acrylic acid or methacrylic acid, wherein l) \ i; : uk1 I »·

CH 2 O

I // CK2 = C-C {2}: \ or1 »· · * 1 t» »i · * ·» · * «

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»112246 6

O

CH2-CH-C S3 (3) \ /

OF

V

CH 3 O

I ff CH2 = C-C RS (4) \ /

K

wherein R 1, R 2, R 3, R 5 are C 6 -C 22 alkyl, especially C 10 -C 18, R 4 and R 6 are alkyl groups having 1 to 4 carbon atoms. The al-5 alkyl groups may be straight-chain or branched, preferably they are straight-chain. Of the two monomers, ester compounds are preferred.

The aircraft antifreeze according to the invention usually contains from 0.05 to 1.5% by weight, preferably from 0.1 to 10 1% by weight of at least one of the copolymers described, with a percentage by weight relative to the (finished) antifreeze.

The copolymers used in accordance with the invention are known and commercially available. They are made. ·. copolymerizing the administered monomers in the presence of crosslinkers; , At 15. Such copolymerizations have been described in detail. for example, US-A-4,744,913, mentioned above.

. Another method of preparation is based on first preparing a homopolymer of acrylic acid or methacrylic acid and then esterifying or amidating it. It is self-evident that the main monomer, acrylic acid or methacrylic acid; V po can also be polymerized as the corresponding acrylates, preferably alkali metal acrylates (the alkali metal is preferably potassium or sodium), another monomer, ester, ··· or amide (for simplicity only acrylic acid and methacrylic acid). Of the cross-linkers mentioned in US-A-4 744 913, the ones from the group of polyunsaturated ethers are also preferred here, with diallyl ether, 7112246 di- or triallyl glyceryl ether, di- or triallyltrimethylol pane ether, tetraallyl oxyethane and di-, tri-, tetra-, penta- or hexa-allyl ethers of sugar alcohols and the corresponding methallyl ethers. The amount of crosslinker in the copolymer is usually 0.01 to 10% by weight, preferably 0.1 to 1% by weight, based on the copolymer. The water-soluble copolymer used in accordance with the invention is composed of the amount of crosslinker, substantially polymerized acrylic acid or methacrylic acid present as the main component, a minor amount of polymerized second monomer and also a small amount of polymerized crosslinker. The preferred copolymer consists of the amount of crosslinker including substantially 75 to 98.99% by weight, preferably 89 to 97.9% by weight of polymerized acrylic acid or methacrylic acid units, 1 to 15% by weight, preferably 2 to 10% by weight of polymerized ester compound or amide compound, 01 to 10% by weight, preferably 0.1 to 1% by weight, of polymerized 20 crosslinkers, the percentage by weight being based on the (finished) copolymer.

: The antifreeze according to the invention contains, in addition to the thickener used, mainly glycols and; water and, in addition, preferably also tensides, corrosive inhibitors and, if necessary, pH adjusters to adjust the pH between 7 and 11, preferably between 7.5 and 9.

As glycols, the antifreeze according to the invention preferably contains from the group of alkylene glycols ... having from 2 to 3 carbon atoms and from the group of oxalkylene glycols having from 4 to 6 carbon atoms. Preferred glycol compounds are ethylene glycol, propylene glycol (1,2-propylene glycol or 1,3-propylene glycol), diethylene glycol, dipropylene glycol, or a mixture of two or more of these glycols, with propylene glycol being particularly preferred. Glycols act primarily to lower the freezing point and, in addition to water, are the main component of s 112246. Preferably deionized water is used as the water.

Fatty alcohol alkoxylates or arylalkyl sulfonates or a mixture thereof are preferably used as surfactants. The alkoxylate is preferably one having 1 to 10, preferably 1 to 5 ethylene oxide units, propylene oxide units or a mixture thereof, with ethylene oxide alone being preferred. The alkyl group of the fatty alcohol usually contains from 6 to 22 C atoms, preferably from 8 to 18 (ΓΙΟ) atoms, and may be straight-chain or branched, with straight-chain being preferred and saturated or unsaturated having preferably 1 to 3 double bonds. octyl, decyl, dodecyl, isotridecyl and stearyl alcohols, in addition oleyl, co-15 cosalkyl and tallow alkyl alcohols and mixtures of fatty alcohols having a C12 alkyl group and a C14 alkyl group (C12 / C14 fatty alcohol) which is ethoxylated with from 1 to 5 moles of ethylene oxide The alkylarylsulfonate is preferably potassium and / or sodium alkylarylsulfonate having one or more, preferably one or two, sulfonate groups (SO3K or SO3Na groups), one or more, preferably; one or two groups of 5 to 18 carbon atoms, preferably 12 to 18 carbon atoms, and one or more, preferably one or two benzene rings. 25 alkali metal (potassium and / or sodium) alkylbenzene. . sulfonates having from 12 to 18 carbon atoms in the alkyl group.

Since hydrocarbon mixtures, such as those formed in the refining of petroleum for example, can also be used as starting materials for the preparation of alkylarylsulfonates, the alkyl group may also refer to such mixtures. In this case, the number of carbon atoms is preferably 12 to 18 (i.e., the average number is 15).

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Common compounds for glycols »· '' 'and aqueous liquids may be used as corrosion inhibitors. So, * 35 pivotal corrosion inhibitors include alkali metal phosphates, »1» lower alkyl phosphates such as ethyl phosphate, dimethyl, 112246 phosphate, isopropyl phosphate and the like, imidazoles such as 1H-imidazole, triazole, benzimidazole, benzimidazole, and tolyltriazole, with triazoles being preferred.

The basic compounds are used to adjust the pH to L 7 to 10, preferably 7.5 to 9. Preferably, substances of the alkali metal hydroxide group, such as NaOH and KOH, alkylamines such as butylamine, hexylamine, octylamine and isonylonyl and alkanol-10 amines are used. , such as mono-, di- and triethanolamine. Alkali metal hydroxides are particularly preferred.

The de-icing agent and antifreeze agent of the invention are prepared by mixing the individual (known and commercially available) components in an arbitrary order, for example in a container equipped with a stirrer.

Taking into account all the components described above, the de-icing fluid of the invention consists essentially of a) 35 to 70% by weight, preferably 40 to 60% by weight, of at least one glycol selected from the group consisting of 2 to 3 carbon atoms of alkylene glycols and 4 to 6 carbon atoms b) 0.05 to 1.5% by weight of at least one water-soluble cross-linked copolymer as a thickener consisting essentially of polymerized units of acrylic acid or methacrylic acid in an amount of from 85 to 99% by weight and of monoacrylic acid or methacrylic acid with esters of acrylic acid or methacrylic acid; the ester group has a C6-C22 alkyl group and one or two C6-C22 alkyl groups

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C) 0.02 to 1.5% by weight, preferably 0.05 to 1% by weight of at least one surfactant of the group of fatty alcohol alkoxylates and arylalkylsulfonates as described above. D) 0.01 to 1% by weight, preferably 0.03 to 0.7% by weight, of at least one corrosion inhibitor for glycols and aqueous liquids, e) at least one basic compound for adjusting the pH to 7-11 and f) water; which has been added as a supplement to 100% by weight, whereby the values are by weight of the substance.

As mentioned above, the copolymer used according to the invention must be water soluble. Water solubility is when a clear solution is obtained by dissolving up to 10 g in 1000 g of water at about 20 ° C, adjusted to pH 7 with alkali metal hydroxide. As an additional feature, the copoly-15 as a 0.2 wt.% Aqueous solution at 20 ° C and pH 7 (adjusted with an alkali metal hydroxide, unless otherwise obvious) has a viscosity of 1000 to 20,000 mPas, measured in Brook. field viscometer using a value of 20 rpm at Up to 20 rpm.

The Type II deicing fluid according to the invention meets the requirements described at the outset. The new thickener also provides an unexpectedly good flow behavior for the high viscosity (yield limit) of the deicing agent having a long "hol, dovertime"; exacerbation. Thus, with the new thickener, it is possible to raise the opposite in both properties, holdover t> * r j> 'me, and outflow behavior. This surprising result is apparently the result of the wait for the thickener described; '30 pseudoplastic behavior resulting in a significant reduction in viscosity as surgery increases and thus the required low thickness of the remnant, ···, removal film in the test "Aerodynamic

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Acceptance Test ”.

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11 112246

The invention is further elucidated by the following Examples 1 and 2 according to the invention and the comparative example.

Example 1 A Type II aircraft antifreeze having the following composition was prepared using the following procedure: 50.00% w / w 1,2-propylene glycol 0.05% w / w benzotriazole 10 0.40% w / w dodecylbenzenesulfonate sodium - salt 0.10% by weight of a fatty alcohol ethoxylate having a fatty alcohol of 12 to 14 carbon atoms ethoxylated with 2 moles of ethylene oxide in a 0.30% by weight cross-linked acrylic acid / dodecyl methacrylate copolymer consisting of 96.5 wt% polymerized acrylic acid and 3.5 wt% polymerized methacrylic acid dodecyl ester 0.093 wt% sodium hydroxide 20 0.019 wt% potassium hydroxide 49.038 wt% water.

The copolymer, as well as the benzotriazole and the surfactants, were dissolved in water with vigorous stirring at a temperature of about 20 ° C. Subsequently, 1,2-propylene glycol was added and the pH was adjusted to 7-7.4 with sodium and potassium hydroxide (in each case about 10% w / w aqueous solution).

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The resulting antifreeze was tested for viscosity, "Water Spray Endurance Time" and "Boundary Layer Displacement Thickness, d *" for "Aerody-30 namic Acceptance Test". The results are summarized in the following Tables 1 and 2: '·· Table 1: Viscosity values at 0 ° C at shear speeds of 0.084, 0.84, 8.4 and 16.8 s' 1 and viscosity values below 35 ° C. at said rising shear rates, expressed as a percentage of the viscosity value at a shear rate of 0.084 s "1.

Shear rate (s "1) 0.084 0.84 8.4 16.8

Viscosity (mPas) 5000 1500 630 500 5 Viscosity decrease (%) 0 70.0 87.4 90.0

Table 2 "Water Spray Endurance Time" and "Boundary Layer Displacement Thickness, d *" in "Aerodynamic Acceptance Test".

10 Example- Requirements of ISO 11078 ki 1

Water Spray Endurance 15 Time at -5 ° C (min) 34> 30

Boundary Layer Displacement Thickness, d * at -30 ° C (mm) 8.5 <10.5 20

Boundary Layer Displacement Thickness, d * at -10 ° C (mm) 8.0 <9.5

Example 2 A Type II aircraft anti-freeze, having the following composition, was prepared in Example 1! : as described: 51.00 wt% 1,2-propylene glycol ', · 0.05 wt% tolyltriazole:, *. 30 0.40% by weight of sodium,,, salt of dodecylbenzenesulfonate, 0.33% by weight of a cross-linked acrylic acid / octadecyl, copolymer of lime methacrylate consisting of 95% by weight of polymerized acrylic acid and 5% by weight of * ·· ** 35 octadecyl esters of methacrylic acid polymerized with 0.118 wt.% Sodium hydroxide (as a 10 wt.% Solution) in 48.102 wt.% Water.

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The resulting antifreeze (pH 7.2) was tested as in Example 1. The results are summarized in the following Tables 3 and 4:

Table 3 5 Viscosity values at 0 ° C at shear rates of 0.084, 0.84, 8.4 and 16.8 s'1 and viscosity decrease at said rising shear rates as a percentage of the viscosity value at 0.084 s'1.

10 Shear rate (s'1) 0.084 0.84 8.4 16.8

Viscosity (mPas) 7400 2450 910 680

Viscosity decrease (%) 0 67.0 87.8 90.8

Table 4 "Water Spray Endurance Time" and "Boundary Layer 15 Displacement Thickness, d1" in "Aerodynamic Acceptance Test".

For example, requirements of ISO 11078 ki 2 20

Water Spray Endurance

Time at -5 ° C (min) 34> 30. Boundary Layer Displacement '; 25 Thickness, d1 *,, 1 at -30 ° C (mm) 10.0 <10.5 ”Boundary Layer Displacement

Thickness, d1; ·. 30 at -10 ° C (mm) 9.0 <9.5 • ·> »

Comparative Example

An aircraft anti-freeze type II having the following composition was prepared using the following procedure: 35 51.00 mass% 1,2-propylene glycol 0.05 mass% benzotriazole 0.40 mass% Sodium V. salt of dodecylbenzenesulfonate 112246 14 0.10 wt.% of a fatty alcohol ethoxylate having a fatty alcohol of 12 to 14 C atoms and ethoxylated with 2 moles of ethylene oxide 0.30 wt.% of a crosslinked polyacrylic acid. % sodium hydroxide 0.017 mass% potassium hydroxide 48.047 mass% water.

Polyacrylic acid as well as benzotriazole and surfactants were dissolved in water with vigorous stirring at 10 to 20 ° C. Subsequently, 1,2-propylene glycol was added and the pH was adjusted to 7-7.4 with sodium and potassium hydroxide (in each case about 10% w / w aqueous solution).

The resulting antifreeze was tested as in Example 1. The results are summarized in the following Tables 5 and 6:

Viscosity values at 0 ° C at shear rates of 0.084, 0.84, 8.4 and 16.8 s -1 and viscosity reduction at said rising shear rates as a percentage of viscosity value at shear rate of 0.084 s 1.

Shear rate (s "1) 0.084 0.84 8.4 16.8

Viscosity (mPas) 3800 1700 790 620 M. · Viscosity Decrease (%) 0 55.3 79.2 83.7; '·· Table 6 2 5 "Water Spray Endurance Time" and "Boundary Layer; Displacement Thickness, d *" in the "Aerodynamic Acceptance Test".

* Comparative 3 0 requirements according to ISO 11078 example

Water Spray Endurance

Time at -5 ° C (min) 34> 30 I · 35 ° Boundary Layer Displacement Thickness, d * at -30 ° C (mm) 12.0 <10.5

Boundary Layer Displacement '··· ’40 Thickness, d * at -10 ° C (mm) 10.0 <9.5

Claims (8)

112246 An aircraft de-icing and antifreeze agent based on glycols and water, wherein the 5 thickeners are water-soluble crosslinked acrylic polymers, characterized in that the thickener is a water-soluble crosslinked copolymer comprising essentially 85 to 99% by mass of acrylic acid or units and from 1 to 15% by weight of an ester or amide of ak-10 acrylic or methacrylic acid, the latter being represented by the formulas o / CH 2 »CH-C (1) 1, UK 1 CH 2 O! // CH 2 -C ** C (2) XOR 2 ',' 0, ', // _ •, · CH 2 »CH-C R 3 (3) \ /: ·· n V 4. . : '· *: Chj o' I f / CH2 = CC R5 (4) \ / K * "· \ j 6 ··;. · 15 R et, ···, where 'y R1, R2, R3, R5 is C 6 -C 22 alkyl,: R 4, R 6 is an alkyl group having 1 to 4 carbon atoms. 2. A substance according to claim 1, characterized in that the thickener is a water-soluble cross-linked copolymer 112246 consisting essentially of 75 to 98.99% by weight of polymerized units of acrylic acid or methacrylic acid, 1 to 15% by weight of a polymer of acrylic acid or methacrylic acid. , and 5 0.01-10% by weight of polymerized crosslinker, whereby the percentage by weight is based on the copolymer. Substance according to Claim 1 and / or 2, characterized in that each of the alkyl groups or groups contains from 10 to 18 C atoms. Substance according to one or more of Claims 1 to 3, characterized in that it contains from 0.05 to 1.5% by weight of a water-soluble cross-linked copolymer, the percentage by weight being based on antifreeze. Substance according to one or more of Claims 1 to 4, characterized in that it contains, as other components, at least one surfactant from the group of fatty alcohol alkoxylates and arylalkyl sulfonates, at least one corrosion inhibitor for glycols and aqueous liquids and at least one alkaline compound. value from 7 to 11 in each effective amount. . The substance according to claim 1, characterized in that it consists essentially of 25% by weight of 35 to 70% by weight of at least one glycol. . lia selected from the group consisting of alkylene glycols having 2 to 3 carbon atoms and oxalkyl glycols having 4 to 6 carbon atoms, b) 0.05 to 1.5% by weight of at least one water - 30 soluble cross - linked copolymers in the form of a thickener consisting essentially of acrylic acid or methacrylic; of polymerized units of meat acid in quantities of 85 to 99% by mass, ···. and of the polymerized units of the ester or * 'amide of acrylic acid or meth acrylic acid having in the ester group: 35 C 6 -C 22 alkyl groups and one or two C 6 -C 22 alkyl groups in the 1 amide group in an amount of 1 to 15% by weight. 1 to 2246 (c) 0.02 to 1.5% by weight of at least one tenside from the group of fatty alcohol alkoxylates and arylalkylsulfonates; (d) 0.01 to 1% by weight of at least one corrosion inhibitor for glycol-5 and aqueous liquids, e) and at least one basic compound for adjusting the pH to between 7 and 11; and f) water added as a supplement to 10 to 100% by weight, the values being by weight relative to the antifreeze. 7. A substance according to claim 6, characterized in that the fatty alcohol alkoxylate is a fatty alcohol ethoxylate having from 1 to 10 ethylene oxide units. The substance according to claim 6, characterized in that the alkyl group or alkyl groups of the ester or amide each have from 10 to 18 carbon atoms and the fatty alcohol alkoxylate is a fatty alcohol ethoxylate with 20 to 1 15 ethylene oxide units. ', I • 1 · »» I »1 <» * I · t I t »» t I t 1 »t t I 1 I» 112246