Use of an essentially anhydrous composition as a coolant and antifreeze for fuel cells, accumulators and batteries

Description

[0001] The present invention relates to novel, essentially water-free antifreeze agents for cooling systems, which can be used as such, i.e. without further dilution with water, as coolants and antifreeze agents and to their use in cooling systems in electric vehicles with fuel cells and / or batteries, and / or in hybrid vehicles comprising electric vehicles with fuel cells and / or batteries with internal combustion engines, preferably in motor vehicles, particularly preferably in passenger and commercial vehicles (so-called light and heavy duty vehicles).

[0002] Fuel cells and / or batteries for mobile use, especially in motor vehicles, must be able to operate even at low outside temperatures of down to approximately minus 40°C. A frost-protected coolant circuit is therefore essential.

[0003] Furthermore, when batteries are quickly charged, temperatures of over 100 °C are reached, so that the heat must be dissipated in order not to damage the respective component.

[0004] The use of conventional monoalkylene glycol-based coolants used in combustion engines, optionally in combination with glycerin, would not be possible in fuel cells and / or batteries without complete electrical insulation of the cooling channels. These coolants have excessive electrical conductivity due to the salts and ionizable compounds they contain as corrosion inhibitors, which would negatively impair the function of the fuel cell or battery. Furthermore, in the event of a battery leakage, for example, if the anode and cathode are short-circuited with the coolant, there is a risk of a short circuit and / or the evolution of hydrogen gas through electrolysis, which poses an additional hazard.

[0005] For this purpose, water and ethylene glycol-containing coolants with low conductivity are known (see e.g. US 2015 / 266370).

[0006] WO 95 / 07323 discloses anhydrous coolants with a water content of less than 0.5 wt% based on propylene glycol and optionally ethylene glycol, but only for internal combustion engines. Use for cooling electrical components is not suggested.

[0007] Furthermore, it is necessary that the coolant retains its initially low electrical conductivity over a long period of time and does not through various decomposition processes, mostly with the formation of ions, increase their conductivity.

[0008] EP 1399523 discloses coolants for fuel cells based on water / monoethylene glycol, which contain azole derivatives and optionally orthosilicic acid esters as inhibitors.

[0009] Because water is a key component in conventional engine coolants, their operating temperature is limited to the boiling point of water in the respective mixtures at operating pressure. For example, mixtures of water and monoethylene glycol, a typical conventional engine coolant, typically boil at approximately 110 to 120 °C at normal pressure.

[0010] Anhydrous coolant concentrates are widely described in the prior art, e.g., in US Pat. No. 8,394,287, in which a radiator protection component, usually monoethylene glycol, is mixed with various additives, such as corrosion inhibitors, antioxidants, antifoam agents, bittering agents, and colorants. US Pat. No. 8,394,287 additionally describes the presence of at least one other radiator protection component, such as monopropylene glycol, higher ethylene glycol homologues, or glycerin, in the concentrate.

[0011] The purpose of these coolant concentrates is always the subsequent dilution with water for use as a coolant (usually with a water content of 30 to 70 vol%); the use of the undiluted concentrates as a coolant is not intended.

[0012] This is the case, for example, in WO 2003 / 74626 A1 and WO 2018 / 95759 A1, which each describe aqueous coolant compositions and their preparation from concentrates by dilution with water. The use of undiluted concentrates as coolants is neither described nor suggested.

[0013] So-called super concentrates are also often described, which are essentially highly concentrated formulations of the above additives in a relatively small amount of coolant component, usually monoethylene glycol or monopropylene glycol.

[0014] The purpose of these super concentrates is always to subsequently dilute them with a radiator protection component to produce the coolant concentrate, which is then used to produce the actual coolant. The undiluted super concentrates are not intended for use as coolants.

[0015] Monoethylene glycol boils at 197 °C at atmospheric pressure, so compositions containing monoethylene glycol exhibit a significant vapor pressure at temperatures above approximately 170 °C, which limits their use as heat transfer fluids at high temperatures. The same applies to monoethylene glycol monomethyl ether (boiling point at atmospheric pressure 124 °C) and monopropylene glycol (boiling point at atmospheric pressure 188 °C).

[0016] Although glycerin, a component of engine coolant, has a relatively high boiling point of approximately 290 °C, it decomposes at this point. Thus, glycerin is prone to decomposition reactions at high temperatures, making it less suitable as a heat transfer fluid under such conditions.

[0017] Thus, water and the lower alkylene glycols, especially monoalkylene glycols, and their ethers as well as glycerin frequently used in radiator protection fluids have significant disadvantages when used as heat transfer fluids at high temperatures.

[0018] If heat is to be transferred at higher temperatures, the cooling system must either be designed for higher pressures or alternatively, oils, such as mineral oils, synthetic oils, or fatty acid esters, or fluorinated hydrocarbons, must be used as coolants. The former is technically complex, so cooling systems are usually designed open to the environment. The latter have the disadvantages, among others, of having a low heat capacity and, due to the open design of the cooling systems, forming two phases when water penetrates due to their low water tolerance.

[0019] The task was therefore to develop coolants for use in batteries or fuel cells in electric vehicles and / or in hybrid vehicles consisting of electric vehicles with fuel cells and / or batteries with combustion engines, which can be used at higher temperatures and have a high heat capacity, but at the same time are suitable for use in open cooling systems and are water compatible.

[0020] Furthermore, they should have low conductivity and maintain this conductivity even during operation, which requires particularly low corrosion, since corrosion means an introduction of ions into the coolant, which would increase the electrical conductivity.

[0021] The object was achieved by using a substantially anhydrous composition containing (A) at least one alkylene glycol derivative of formula (I) wherein R 1< hydrogen or C 1 - C 4 -alkyl, preferably hydrogen, methyl or ethyl, particularly preferably hydrogen or methyl and very particularly preferably hydrogen, R 2< C 1 - C 4 -alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or n-butyl and very particularly preferably methyl, R 3< hydrogen or methyl, preferably hydrogen and n is on average a number from 3.0 to 4.0, and (B) at least one corrosion inhibitor selected from the group consisting of (Ba) ortho-silicic acid esters and / or alkoxyalkylsilanes (Bb) azole derivatives (Bc) compounds of the general formula (II) wherein R 4< is an organic radical having 6 to 10 carbon atoms, in particular a straight-chain or branched, preferably straight-chain alkyl or alkenyl radical having 6 to 10 carbon atoms, preferably 7 to 9 and particularly preferably 8 carbon atoms, p and q independently of one another are a positive integer from 1 to 30, preferably 1 to 20, particularly preferably 1 to 10, very particularly preferably 1 to 5 and in particular 1 to 3, especially 1 or 2 and each X i for i = 1 to p and 1 to q is independently selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3 )-O-, -CH(CH 3 )-CH 2 -O-, -CH 2 -C(CH 3 ) 2 -O-, -C(CH 3 ) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5 )-O-, -CH(C 2 H 5 )-CH 2 -O-, -CH(CH 3 )-CH(CH 3 )-O-, -CH 2 -CH 2 -CH 2 -O- and -CH 2 -CH 2 -CH 2 -CH 2 -O-, preferably selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3 )-O- and -CH(CH 3 )-CH 2 -O-, particularly preferably it is -CH 2 -CH 2 -O-, with the proviso,that the composition contains less than 1% by weight of water, preferably less than 0.75, particularly preferably less than 0.5, very particularly preferably less than 0.4, in particular less than 0.3 and especially less than 0.2% by weight, a proportion of alkylene glycol derivatives of the formula (I) with n ≤ 2 of not more than 10% by weight, preferably not more than 8, particularly preferably not more than 6, very particularly preferably not more than 5, in particular not more than 4 and especially not more than 3% by weight, a proportion of alkylene glycol derivatives of the formula (I) with n ≥ 5 of not more than 5% by weight, preferably not more than 4, particularly preferably not more than 3, very particularly preferably not more than 2.5 and especially not more than 2% by weight, a proportion of monoethylene glycol, diethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propylene glycol and Glycerol of not more than 10% by weight each, preferably not more than 8, particularly preferably not more than 6,very particularly preferably not more than 5 and especially not more than 3 wt%, wherein it has an electrical conductivity according to ASTM D 1125 at 25 °C of not more than 50 µS / cm, preferably not more than 25, particularly preferably not more than 15, very particularly preferably not more than 10 and in particular not more than 5 µS / cm without further dilution with water as a coolant and antifreeze for cooling systems in fuel cells, accumulators and / or batteries.

[0022] The individual components are described in more detail below: Component (A)

[0023] In the at least one alkylene glycol derivative of formula (I) mean R 1< hydrogen or C 1 - C 4 -alkyl, preferably hydrogen, methyl or ethyl, particularly preferably hydrogen or methyl and very particularly preferably hydrogen, R 2< C 1 - C 4 -alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or n-butyl and very particularly preferably methyl R 3< hydrogen or methyl, preferably hydrogen and n is on average a number from 3.0 to 4.0.

[0024] Preferred alkylene glycol derivatives (A) are Triethylene glycol monomethyl ether Triethylene glycol monoethyl ether Triethylene glycol mono-n-butyl ether Triethylene glycol dimethyl ether Triethylene glycol diethyl ether Triethylene glycol di-n-butyl ether Tetraethylene glycol monomethyl ether Tetraethylene glycol monoethyl ether Tetraethylene glycol mono-n-butyl ether Tetraethylene glycol dimethyl ether Tetraethylene glycol diethyl ether Tetraethylene glycol di-n-butyl ether tripropylene glycol monomethyl ether tripropylene glycol monoethyl ether tripropylene glycol mono-n-butyl ether tripropylene glycol dimethyl ether tripropylene glycol diethyl ether tripropylene glycol di-n-butyl ether tetrapropylene glycol monomethyl ether tetrapropylene glycol monoethyl ether tetrapropylene glycol mono-n-butyl ether tetrapropylene glycol dimethyl ether tetrapropylene glycol diethyl ether tetrapropylene glycol di-n-butyl ether

[0025] Ethylene glycol ethers are preferred over propylene glycol ethers.

[0026] Furthermore, monoalkyl ethers are preferred over dialkyl ethers.

[0027] Component (A) is preferably a substantially pure compound of formula (I) with n = 3 or a mixture of compounds of formula (I) with n = 3 and n = 4. The arithmetic mean n for the compounds of formula (I) in the mixture is preferably from 3.0 to 3.6, particularly preferably from 3.0 to 3.5, very particularly preferably from 3.05 to 3.4, in particular from 3.1 to 3.3 and especially from 3.15 to 3.25.

[0028] The radicals R 1< and R 2< for the compounds in the mixture can be the same or different, preferably they are the same.

[0029] "Substantially pure" means that compounds of formula (I) with n = 3 or n = 4 also contain, to a certain extent, the homologous compounds with higher and lower values ​​for n.

[0030] As a rule, the purity of compounds of formula (I) with n = 3 is at least 80% by weight, preferably at least 85% by weight, very particularly preferably at least 90% by weight, in particular at least 95% by weight, and especially at least 97.5% by weight. The remainder is predominantly compounds of formula (I) with n = 2 and n = 4.

[0031] In contrast, for compounds of formula (I) with n = 4, the degree of purity is usually only above 50 wt%, preferably at least 55, particularly preferably at least 60 wt%. The remainder is predominantly compounds of formula (I) with n = 3 and, to a lesser extent, n = 5.

[0032] Preferred components (A) with essentially pure compounds are Triethylene glycol monomethyl ether Triethylene glycol monoethyl ether Triethylene glycol mono-n-butyl ether

[0033] Preferred components (A) with mixtures of compounds of formula (I) with n = 3 and n = 4 are Triethylene glycol monomethyl ether mixed with tetraethylene glycol monomethyl ether Triethylene glycol monoethyl ether mixed with tetraethylene glycol monoethyl ether Triethylene glycol mono-n-butyl ether mixed with tetraethylene glycol mono-n-butyl ether

[0034] Conceivable, although less preferred, are mixtures of compounds of formula (I) with n = 3 and n = 4 which have different radicals R 1<.

[0035] Such mixtures are Triethylene glycol monomethyl ether mixed with tetraethylene glycol monoethyl ether. Triethylene glycol monomethyl ether mixed with tetraethylene glycol mono-n-butyl ether. Triethylene glycol monoethyl ether mixed with tetraethylene glycol monomethyl ether. Triethylene glycol monoethyl ether mixed with tetraethylene glycol mono-n-butyl ether. Triethylene glycol mono-n-butyl ether mixed with tetraethylene glycol monomethyl ether. Triethylene glycol mono-n-butyl ether mixed with tetraethylene glycol monoethyl ether.

[0036] Conceivable, although less preferred, are mixed alkylene glycol derivatives of the formula (I) in which R 3< for each n can be independently the same or different, ie tri- and tetraalkylene glycol derivatives of the formula (I) from mixtures of ethylene oxide and propylene oxide.

[0037] In mixtures of compounds of formula (I) where n = 3 and n = 4, the weight ratio is preferably from 100:0 to 40:60, particularly preferably from 95:5 to 50:50, very particularly preferably from 90:10 to 60:40, in particular from 85:15 to 70:30 and especially from 85:15 to 75:25. Component (B)

[0038] Component (B) is at least one corrosion inhibitor selected from the group consisting of (Ba) ortho-silicic acid esters and / or alkoxyalkylsilanes (Bb) azole derivatives and (Bc) compounds of the general formula (II)

[0039] The ortho-silicic acid esters (Ba) are compounds of the formula Si(OR 5< ) 4 in which R 5< is in each case an organic radical having 1 to 6 carbon atoms, preferably a straight-chain or branched, preferably straight-chain alkyl radical having 1 to 6 carbon atoms or an aryl radical having 6 carbon atoms, particularly preferably an alkyl radical having 1 to 4 carbon atoms, very particularly preferably an alkyl radical having 1 or 2 carbon atoms.

[0040] Examples of this are ortho-Silica tetramethyl ester ortho-Silica tetraethyl ester ortho-Silica tetra-n-butyl ester ortho-Silica tetraphenyl ester

[0041] Preference is given to ortho-silicic acid tetramethyl ester ortho-silicic acid tetraethyl ester

[0042] Ortho-silicic acid tetraethyl ester is particularly preferred.

[0043] The alkoxyalkylsilanes that are less preferred than the ortho-silicic acid esters are preferably triethoxymethylsilane, diethoxydimethylsilane, ethoxytrimethylsilane, trimethoxymethylsilane, dimethoxydimethylsilane and methoxytrimethylsilane.

[0044] In the context of this document, azole derivatives (Bb) are five-membered heterocyclic compounds with 2 or 3 heteroatoms from the group nitrogen and sulfur, which contain no or a maximum of one sulfur atom incorporated into the ring and which can optionally carry an aromatic or saturated six-membered anellant.

[0045] These five-membered heterocyclic compounds (azole derivatives) usually contain two N atoms and no S atom, three N atoms and no S atom, or one N atom and one S atom as heteroatoms.

[0046] Preferred groups of the azole derivatives mentioned are fused imidazoles and fused 1,2,3-triazoles of the general formula or

[0047] in which the variable R denotes hydrogen or a C 1 to C 10 alkyl radical, in particular methyl or ethyl, and the variable X denotes a nitrogen atom or the group CH.

[0048] Typical and preferred examples of azole derivatives of the general formula (III) are benzimidazole (X = CH, R = H), benzotriazole (X = N, R = H), and tolutriazole (tolyltriazole) (X = N, R = CH 3 ). A typical example of an azole derivative of the general formula (IV) is hydrogenated 1,2,3-tolutriazole (tolyltriazole) (X = N, R = CH 3 ).

[0049] Another preferred group of the azole derivatives mentioned are benzothiazoles of the general formula (V) in the the variable R has the meaning given above and the variable R' denotes hydrogen, a C 1 - to C 10 -alkyl radical, in particular methyl or ethyl, or in particular a mercapto group (-SH). Conceivably, although less preferably, R' can also be a carboxyalkyl radical of the formula -(C m H 2m )-COOR", where m is a number from 1 to 4 and R" denotes C 1 - to C 10 -alkyl, in particular methyl or ethyl, or C 6 - to C 12 -aryl. Examples thereof are (2-benzothiazylthio)-acetic acid ester or 3-(2-benzothiazylthio)-propionic acid ester. A typical example of an azole derivative of the general formula (V) is 2-mercaptobenzothiazole.

[0050] Furthermore, non-fused azole derivatives of the general formula (VI) in which the variables X and Y together denote two nitrogen atoms or one nitrogen atom and a CH group, for example 1H-1,2,4-triazole (X = Y = N) or preferably imidazole (X = N, Y = CH).

[0051] Benzimidazole, benzotriazole, tolutriazole, hydrogenated tolutriazole or mixtures thereof, in particular benzotriazole or tolutriazole, especially tolutriazole, are very particularly preferred as azole derivatives for the present invention.

[0052] The azole derivatives mentioned are commercially available or can be prepared using conventional methods. Hydrogenated benzotriazoles such as hydrogenated tolutriazole are also accessible according to DE-A 1 948 794 and are also commercially available.

[0053] In the general formula (II) of component (Bc) R 4< is an organic radical having 6 to 10 carbon atoms, in particular a straight-chain or branched, preferably straight-chain alkyl or alkenyl radical having 6 to 10 carbon atoms, preferably 7 to 9 and particularly preferably 8 carbon atoms, p and q independently of one another are a positive integer from 1 to 30, preferably 1 to 20, particularly preferably 1 to 10, very particularly preferably 1 to 5, in particular 1 to 3, especially 1 or 2 and each X i for i = 1 to p and 1 to q is independently selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3 )-O-, -CH(CH 3 )-CH 2 -O-, -CH 2 -C(CH 3 ) 2 -O-, -C(CH 3 ) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5 )-O-, -CH(C 2 H 5 )-CH 2 -O-, -CH(CH 3 )-CH(CH 3 )-O-, -CH 2 -CH 2 -CH 2 -O- and -CH 2 -CH 2 -CH 2 -CH 2 -O-, preferably selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3 )-O- and -CH(CH 3 )-CH 2 -O-, particularly preferably it is -CH 2 -CH 2 -O-.

[0054] In the compounds of formula (II), the structural element R 4< -N< is preferably derived from fatty amines, which are preferably obtainable by hydrogenation and amination of fatty acids and esters, particularly preferably by hydrogenation and amination of the above-mentioned fatty acids or amination of fatty alcohols.

[0055] As radicals R 4<, alkyl radicals are preferred over alkenyl radicals.

[0056] In a specific embodiment, p and q are independently 1, 2 or 3, more preferably 1 or 2 and most preferably 1.

[0057] In a preferred embodiment, the fatty amines are n-hexylamine, 2-methylpentylamine, n-heptylamine, 2-heptylamine, iso-heptylamine, 1-methylhexylamine, n-octylamine, 2-ethylhexylamine, 2-aminooctane, 6-methyl-2-heptylamine, n-nonylamine, isonylamine, n-decylamine and 2-propylheptylamine or mixtures thereof.

[0058] Particularly preferred are n-hexylamine, n-octylamine, 2-ethylhexylamine and n-decylamine, very particularly preferred are n-octylamine and 2-ethylhexylamine and in particular n-octylamine.

[0059] Of particular note are di-, tri-, quadruple-, penta- and sextuple-ethoxylated n-octylamine, as well as mixtures thereof, and di-, tri-, quadruple-, penta- and sextuple-ethoxylated n-hexylamine, as well as mixtures thereof.

[0060] For the alkoxylated amines of the general formula (II), the degree of alkoxylation refers to the sum (p + q), i.e. to the average total number of alkoxylation units per molecule of amine.

[0061] The compounds (II) are preferably obtainable by reacting the corresponding amines R 4< -NH 2 with alkylene oxides to the desired average statistical degree of alkoxylation, preferably under basic conditions. This is particularly preferred when the structural unit X i is derived from ethylene oxide or propylene oxide, preferably from ethylene oxide.

[0062] The compositions according to the invention generally contain Component (A): 95 to 99.9 wt%, preferably 96 to 99.8, particularly preferably 97 to 99.5, very particularly preferably 97.5 to 99 wt%, and in particular 98 to 99 wt%. Component (B): 0.1 to 5 wt%, preferably 0.2 to 4, particularly preferably 0.5 to 3, very particularly preferably 1 to 2.5 wt%, and especially 1 to 2 wt%. Component (C) - additional optional corrosion inhibitors

[0063] In addition to at least one of the above components (B) as a mandatory corrosion inhibitor, the composition according to the invention may optionally contain at least one further corrosion inhibitor which is different from those listed under (B).

[0064] However, it is a preferred embodiment of the present invention that apart from the above-mentioned components (B), no further corrosion inhibitors (C) are contained in the composition.

[0065] Examples of components (C) are aliphatic, cycloaliphatic or aromatic amines having 2 to 15 carbon atoms, which may additionally contain ether oxygen atoms or hydroxyl groups and which are different from the compounds (Bc) of formula (II).

[0066] The amines (C) preferably have 2 to 9, in particular 4 to 8, carbon atoms. The amines (C) are preferably tertiary amines. The amines (C) preferably contain 0 to 3 ether oxygen atoms or 0 to 3, preferably 0 to 2, hydroxyl groups. Typical examples of amines (C) are ethylamine, propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine, n-nonylamine, isononylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, mono-, di-, and triethanolamine, mono-, di-, and triisopropanolamine, piperidine, morpholine, cyclohexylamine, aniline, and benzylamine. Aliphatic and cycloaliphatic amines (C) are generally saturated.

[0067] Furthermore, the use of fatty acid alkoxylates and fatty alcohol alkoxylates as further corrosion inhibitors is conceivable, as described in WO 18 / 95759 as compounds of formula (V) and (VI) from page 5, line 34 to page 10, line 10, to which reference is hereby made.

[0068] Component (C) is optional and may be present in the compositions according to the invention in amounts of 0 to 2% by weight, preferably 0 to 1.5% by weight, particularly preferably 0 to 1% by weight, most particularly preferably 0 to 0.7% by weight.

[0069] In an expressly preferred embodiment, no component (C) is present. Component (D) - further additives

[0070] The composition according to the invention may optionally contain at least one further additive selected from the group consisting of (Da) bitter substances (Db) dyes (Dc) defoamers (Dd) antioxidants and (De) emulsifiers.

[0071] Bitter substances (Da) may be added for reasons of hygiene and safety in case of ingestion, for example, bitter substances of the denatonium benzoate type. Bitter substances are optional in the compositions according to the present application. Preferably, no bitter substance is present in the composition according to the invention.

[0072] These substances are commercially available and commonly used compounds from the state of the art that can typically be used in coolants.

[0073] One function of the emulsifiers (De) used in the compositions according to the invention is that they can emulsify potential contaminants and / or assembly fluids originating from the cooling system, e.g. polyalkylene glycols or oligomers of glycerol, in the compositions.

[0074] The components (D) are each optional and can be present in the compositions according to the invention independently of one another in amounts of 0 to 0.5 wt%, preferably 0.001 to 0.3 wt% and particularly preferably 0.002 to 0.2 wt%. Properties of the compositions according to the invention

[0075] The compositions according to the invention are subject to the following provisions: They contain less than 1% by weight of water, preferably less than 0.75%, particularly preferably less than 0.5%, very particularly preferably less than 0.4%, in particular less than 0.3% and especially less than 0.2% by weight.

[0076] The low water content according to the invention, together with the choice of component (A), results in the increased boiling point according to the invention, since a higher water content limits the boiling point of a composition to approximately 100 °C plus any boiling point increase. The presence of even small amounts of water drastically lowers the boiling point of the compositions; this effect is known, for example, from brake fluids and leads to different boiling point requirements depending on the water content.

[0077] Furthermore, when the composition is used as a coolant for cooling systems in fuel cells, accumulators and / or batteries, water with a significant electrical conductivity can lead to electrolysis of the composition and undesirable hydrogen evolution, which entails an increased risk of accidents.

[0078] A further requirement of the compositions according to the invention is that they contain a proportion of alkylene glycol derivatives of the formula (I) with n ≤ 2 of not more than 10% by weight, preferably not more than 8, particularly preferably not more than 6, very particularly preferably not more than 5, in particular not more than 4 and especially not more than 3% by weight.

[0079] A higher content of alkylene glycol derivatives of formula (I) with n ≤ 2 would, on the one hand, also undesirably lower the boiling point and, on the other hand, excessively reduce the viscosity of the composition. Too low a viscosity may be undesirable in certain applications, as low-viscosity fluids easily overcome seals and thus cause leaks.

[0080] A further requirement of the compositions according to the invention is that they contain a proportion of alkylene glycol derivatives of the formula (I) with n ≥ 5 of not more than 5% by weight, preferably not more than 4, particularly preferably not more than 3, very particularly preferably not more than 2.5 and especially not more than 2% by weight.

[0081] Conversely, higher homologues result in a high viscosity of the composition, thus making it more difficult to pump. High viscosity requires increased pumping power and thus increased pump energy consumption. Furthermore, higher homologues also have a higher melting point, so there is a risk of precipitation from the composition at low temperatures.

[0082] A further requirement of the compositions according to the invention is that they contain a proportion of monoethylene glycol, diethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propylene glycol and glycerol of not more than 10% by weight each, preferably not more than 8, particularly preferably not more than 6, very particularly preferably not more than 5 and especially not more than 3% by weight.

[0083] In addition to the aforementioned low boiling point of the lower homologues, polyhydric alcohols are relatively unstable to thermal stress and oxidation. A small proportion of these compounds thus increases the stability of the compositions according to the invention.

[0084] The compositions according to the invention preferably have a specific heat capacity at 50 °C of at least 2.0 kJ / kg×K, particularly preferably of at least 2.1, very particularly preferably of at least 2.2 and in particular of at least 2.3 kJ / kg×K.

[0085] The compositions according to the invention preferably have a thermal conductivity of at least 0.15 W / m×K.

[0086] In order to obtain a low conductivity, compounds having a polarizability of not more than 50 C × m 2 < / V are preferably used as components (A), particularly preferably not more than 45, very particularly preferably not more than 40, in particular not more than 35 and especially not more than 30. use

[0087] An advantage of the described essentially anhydrous compositions is that they can generally be used as coolants for cooling systems without further dilution with water, particularly as cooling systems in fuel cells, accumulators, and / or batteries. These coolants also exhibit an antifreeze effect.

[0088] For the latter use, it is crucial that the substantially anhydrous compositions have an electrical conductivity at 25 °C of not more than 50 µS / cm, preferably not more than 25, more preferably not more than 15, most preferably not more than 10 and in particular not more than 5 µS / cm.

[0089] Low electrical conductivity in cooling systems in fuel cells, accumulators and batteries is essential, as otherwise the individual cells can be short-circuited during operation, discharging or charging.

[0090] Damage to the battery cell poses the risk of coolant and electrolyte coming into contact, resulting in the formation of dangerous hydrogen fluoride and other reaction products through the reaction of the protic coolant with the frequently used electrolyte, LiPF6. This risk is further increased by the presence of water, for example, due to the hygroscopic properties of the coolants (see below). For example, AV Plakhotnyk et al., Journal of Fluorine Chemistry, 126 (2005) 27-31, show that when LiPF6 is dissolved in aprotic organic solvents with a water content of just 0.5 wt%, a total of approximately 10 mol% of the LiPF6 used is hydrolyzed over a period of about 23 days.

[0091] Surprisingly, no significant reaction is observed upon contact of the compositions according to the invention with LiPF 6, even in the presence of water. Therefore, the compositions according to the invention are particularly suitable for cooling lithium-ion batteries.

[0092] Following common usage, the terms "battery" and "accumulator" are used here to describe rechargeable, individual, or interconnected storage devices for chemical energy, and "battery" is used as a generic term for both rechargeable and non-rechargeable storage devices. The term "accumulator" is therefore a subset of "battery."

[0093] In order to achieve the low electrical conductivity required according to the invention, it is preferable to avoid salt-form compounds and readily dissociating compounds, especially acids, in the components used. Therefore, in a preferred embodiment, the additional additives described above are used in a form that is essentially non-ionic under the application conditions.

[0094] Since glycol ethers are generally hygroscopic, there is a risk that the water content in the compositions according to the invention will increase over time during storage, especially during open storage, or during use in a cooling system, for example, due to the absorption of atmospheric moisture. This also applies to storage and use in closed systems, since many seals are permeable to air and humidity.

[0095] It is an advantage of the compositions according to the invention that they have an electrical conductivity at 25 °C of not more than 50 µS / cm, preferably not more than 25, particularly preferably not more than 15 µS / cm and very particularly preferably not more than 10 µS / cm, even when up to 5, preferably up to 10, particularly preferably up to 25% by weight, very particularly preferably up to 40 and in particular up to 50% by weight of water are absorbed or added, based on the total mixture.

[0096] A further advantage of the compositions according to the invention is that they are compatible with the most commonly used sealing materials. This applies, for example, to EPDM (ethylene-propylene-diene (monomer) rubbers, preferably according to EN 13956), SBR (styrene-butadiene rubbers), FKM (fluorocarbon rubbers, preferably according to DIN ISO 1629 or ASTM D 1418, such as Viton®), NBR (acrylonitrile-butadiene rubbers), and HNBR (hydrogenated acrylonitrile-butadiene rubbers).

[0097] It is an advantage of the essentially anhydrous compositions according to the invention that, due to their stability against thermal stress and oxidation, an initially low electrical conductivity is also maintained over a longer period of time, since the formation of electrically conductive products as a result of decomposition or oxidation is reduced.

[0098] Therefore, it is a particularly preferred embodiment of the present invention to dilute the compositions according to the invention with up to 40 and even up to 50% by weight of ion-free, preferably demineralized or double-distilled water, based on the total aqueous mixture, and to use them in this form as coolants and antifreezes for fuel cells, since these aqueous coolants and antifreezes also have a sufficiently low conductivity for this specific application.

[0099] "Ionic-free water" refers to water with a neutral pH value in which essentially no ions other than hydroxide and oxonium ions from the autoprotolysis of the water are present. The electrical conductivity of such water at 25 °C is preferably no more than 5 µS / cm, more preferably no more than 3, most preferably no more than 2, and especially no more than 1 µS / cm.

[0100] The essentially anhydrous compositions according to the invention preferably have a boiling point at 1013 hPa (normal pressure) of at least 200 °C, preferably at least 210, particularly preferably at least 220, very particularly preferably at least 230 and in particular at least 250 °C.

[0101] This ensures that the essentially anhydrous compositions remain liquid even at high ambient temperatures and can function as heat transfer media without excessively increasing the vapor pressure above the compositions. Thus, the essentially anhydrous compositions according to the invention can be handled in open systems even at high temperatures.

[0102] As stated above, the essentially anhydrous compositions according to the invention have an advantageous viscosity which is neither too low nor too high.

[0103] They preferably have a kinematic viscosity at 100 °C according to ASTM D445 of at most 4 mm 2< / s, particularly preferably of at most 3 and most preferably of at most 2 mm 2< / s.

[0104] Furthermore, they preferably exhibit a kinematic viscosity at minus 40 °C according to ASTM D445 of not more than 600 mm 2 / s, particularly preferably not more than 500, very particularly preferably not more than 400 and in particular not more than 350 mm 2 / s.

[0105] An advantage of the essentially anhydrous compositions according to the invention is that they exhibit, on the one hand, a lower viscosity and, on the other hand, a smaller change in viscosity over a wide temperature range, preferably from minus 40°C to plus 100°C, than conventional coolants based on water and monoethylene glycol: For example, a mixture of 50% by weight water and 50% by weight monoethylene glycol solidifies at around minus 37°C and is therefore not usable in the preferred temperature range mentioned above. The kinematic viscosity of such a mixture at minus 20°C is about 300 mm 2 / s.

[0106] It is an advantage of the present invention that typical mixtures according to the present invention are not solid at minus 40 °C and have a kinematic viscosity at minus 40 °C of about 250 to 500 mm 2< / s and at minus 20 °C of not more than about 100 mm 2< / s.

[0107] The change in kinematic viscosity in the temperature range from minus 40 °C to plus 100 °C for the essentially anhydrous compositions according to the invention is therefore no more than approximately 500 mm² / s, and thus fluctuates less than the above mixture of water and monoethylene glycol. This means that pumps with a lower flow rate can be used in the cooling system, so that less energy is required to pump the coolant in the cooling system. Proceedings

[0108] Due to the fact that the described essentially water-free compositions have a higher boiling point than the conventional coolants based on water or monoalkylene glycol, a further subject of the present invention is a cooling method for accumulators, fuel cells and batteries of vehicles, in which heat is transferred from a heat source at a higher temperature via at least one first heat exchanger to a coolant, this coolant is led in a cooling circuit to at least one second heat exchanger and there heat is removed from the coolant at a lower temperature, in which as coolant, a substantially water-free composition as described above is used without further dilution with water, the higher temperature is from 60 to 300 °C, preferably 70 to 280, particularly preferably 80 to 250 °C, the lower temperature is from minus 50 to 100 °C, preferably minus 40 to 90, particularly preferably minus 30 to 80 °C and the lower temperature is at least 50 °C lower than the higher temperature.

[0109] It is a preferred embodiment that when using the essentially anhydrous compositions according to the invention with their high boiling point, the pressure in the cooling circuit is not more than 500 hPa, preferably not more than 400, particularly preferably not more than 300 and very particularly preferably not more than 200 hPa above the ambient pressure.

[0110] The higher temperature is, for example, the wall temperature of accumulators, fuel cells or batteries during normal operation of electric vehicles with fuel cells and / or batteries, and / or hybrid vehicles made up of electric vehicles with fuel cells and / or batteries with combustion engines, or during the charging or discharging process of such accumulators or batteries.

[0111] The lower temperature is preferably the ambient temperature with which the heated coolant is brought into contact in the second heat exchanger.

[0112] All heat exchangers can be components that are known per se and are familiar to the expert for these purposes.

[0113] Percent, ppm or parts in this document refer to wt%, wt.ppm or parts by weight unless otherwise stated. Examples Test methods

[0114] Unless otherwise stated, the values ​​given in this document were determined using the following methods: boiling point ASTM D 1120 density ASTM D 1122 electrical conductivity ASTM D 1125 specific heat capacity DIN EN ISO 11357-4 Thermal conductivity Ball gap process Water content ASTM D 1123 Flash point ISO 2719 Ignition temperature DIN 51794 refractive index ASTM D 1218 Reserve alkalinity ASTM D 1121 pH ASTM D 1287 Compositions

[0115] The following compositions were prepared (data in wt%): Comparison:

[0116] Nr 1 2 3 4 5 Triethylene glycol monomethyl ether 95,50 88,50 81,50 74,50 67,50 Tetraethylene glycol monomethyl ether 4,50 11,50 18,50 25,50 32,50 sum 100,00 100,00 100,00 100,00 100,00 Kinematic viscosity, -40 °C, mm 2 < / s (ASTM D 445) 254,3 298,9 319,8 360 393,6 Kinematic viscosity, -20 °C, mm 2 < / s (ASTM D 445) 47,7 53,5 56,6 61,4 65,8 Kinematic viscosity, 100 °C, mm 2 < / s (ASTM D 445) 1,3919 1,4208 1,4658 1,5099 1,5621 Nr 6 7 8 9 10 Triethylene glycol monomethyl ether 93,60 86,60 79,90 72,60 65,60 Tetraethylene glycol monomethyl ether 2,60 9,60 16,60 23,60 30,60 Additive mixture* 2,00 2,00 2,00 2,00 2,00 Diisopropanolamin 1,00 1,00 1,00 1,00 1,00 Octyldiethanolamine 0,80 0,80 0,80 0,80 0,80 sum 100,00 100,00 100,00 100,00 100,00 Kinematic viscosity, -40 °C, mm 2 < / s (ASTM D 445) 284,4 315,3 349,9 389,2 477,6 Kinematic viscosity, -20 °C, mm 2 < / s (ASTM D 445) 52,0 56,3 60,5 65,4 70,4 Kinematic viscosity, 100 °C, mm 2 < / s (ASTM D 445) 1,4934 1,8668 1,8067 1,6869 1,6973 Nr 11 12 13 Triethylene glycol monomethyl ether 92,20 89,20 82,20 Tetraethylene glycol monomethyl ether 4,00 7,00 14,00 Additive mixture* 2,00 2,00 2,00 Diisopropanolamin 0 0 0 Octyldiethanolamine 1,8 1,8 1,8 sum 100,00 100,00 100,00 Kinematic viscosity, -40 °C, mm 2 < / s (ASTM D 445) 262,4 273,91 306,27 Kinematic viscosity, -20 °C, mm 2 < / s (ASTM D 445) 49,2 50,861 55,128 Kinematic viscosity, 100 °C, mm 2 < / s (ASTM D 445) 1,4224 1,4458 1,4895 * The 2 parts of additive mixture used consisted of the non-ferrous metal corrosion inhibitor tolyltriazole, antioxidant and fatty alcohol ethoxylates as corrosion inhibitor dissolved in 1.67 parts of triethylene glycol monomethyl ether.

[0117] The corrosion test yielded the following values ​​for reserve alkalinity before / after corrosion (measured in mL 0.1 M HCl / 10 mL test volume), pH before / after corrosion and corrosion loss in mg / cm 2< over 336h according to ASTM D1384: Nr 1 (cf.) 2 (cf.) 3 (cf.) 4 (cf.) 5 (cf.) Reserve alkalinity against corrosion 0 0 0 0 0 Reserve alkalinity after corrosion 0 0 0 0 0 pH against corrosion 5,84 6,04 6,18 6,1 6,08 pH after corrosion 2,58 2,67 2,68 3,07 3,3 Al 0,05 0,22 0,31 0,12 0,38 Cu -0,16 -0,26 -0,28 -0,3 -0,18 Brass -0,17 -0,3 -0,23 -0,29 -0,19 Steel -3,66 -3,25 -2,27 -1,45 -0,99 Grey cast iron -2,54 -2,51 -2,17 -1,69 -1,24 Soft solder -1,87 -1,36 -1,38 -0,94 -1,02 Nr 6 7 8 9 10 Reserve alkalinity against corrosion 10,8 10,78 10,82 10,85 10,75 Reserve alkalinity after corrosion 8,63 8,56 8,91 8,79 8,77 pH against corrosion 9,5 9,6 9,7 9,8 9,9 pH after corrosion 9,9 9,3 9,9 9,9 10,0 Al 0,04 0,1 0,06 0,06 0,05 Cu -0,43 -0,41 -0,42 -0,43 -0,44 Brass 0,07 0,07 0,07 0,08 0,08 Steel 0,04 0,03 0,03 0,02 0,04 Grey cast iron 0,09 0,11 0,11 0,07 0,14 Soft solder -0,07 -0,06 -0,06 -0,05 -0,05 Nr 11 12 13 Reserve alkalinity against corrosion 7,76 7,98 8,03 Reserve alkalinity after corrosion 6,76 6,25 6,42 pH against corrosion 9,4 9,64 9,68 pH after corrosion 9,4 9,45 9,47 Al 0,05 0,05 0,1 Cu -0,03 -0,02 -0,02 Brass 0,06 0,06 0,07 Steel 0,02 0,03 0,03 Grey cast iron 0,13 0,1 0,08 Soft solder -0,17 -0,18 -0,14

[0118] In the supernatant liquid from the corrosion test according to ASTM D1384, the following Metal contents determined by ICP spectrometry (inductively coupled plasma) [ppm]: Nr 1 (cf.) 2 (cf.) 3 (cf.) 4 (cf.) 5 (cf.) Fe 18 16 8 28 31 Cu 9 7 5 6 9 Al <3 <3 <3 <3 <3 Zn 5 3 <3 3 4 Sn 6 6 3 5 6 Pb 13 7 8 5 8 Nr 6 7 8 9 10 Fe <3 <3 <3 <3 <3 Cu 18 18 18 18 19 Al <3 <3 <3 <3 <3 Zn <3 <3 <3 <3 <3 Sn <3 <3 <3 <3 <3 Pb <3 <3 <3 <3 <3 Nr 11 12 13 Fe <3 <3 <3 Cu 3 <3 3 Al <3 <3 <3 Zn <3 <3 <3 Sn <3 <3 <3 Pb <3 <3 <3

[0119] It can be seen that in the compositions according to the present invention, the introduction of iron ions in particular, but also of copper ions, into the liquid is significantly reduced. This makes it possible to keep the electrical conductivity of the compositions according to the invention low. Furthermore, the pH value is kept stable throughout the corrosion and shows only a slight change.

[0120] This is demonstrated by the following measured electrical conductivities (at 25 °C in µS / cm) before and after corrosion: 1 (Vql) 6 7 8 9 10 11 12 13 from corrosion 0 1,2 1,1 1 0,9 0,9 1,1 0,8 0,7 according to Korr 0,3 1,6 1,4 1,3 1,2 1,3 1,3 1,5 1,3

[0121] It can be seen that there is a greater relative increase in electrical conductivity in the comparison composition than in the compositions according to the invention.

[0122] Corrosion test according to ASTM D1384 and corrosion loss in mg / cm 2< over 4 weeks: Nr 14 15 16 17 18 19 20**** (cf.) Triethylene glycol monomethyl ether 90 86,2 86.2 88,2 89,95 86.2 Tetraethylene glycol monomethyl ether 10 10 10 1 10 10 10 Octyldiethanolamine 1,8 1,8 1,8 1,8 Additive mixture: Tolyltriazole* 0,05 0,05 0,05 Antioxidant** 0,03 0,03 Emulsifiers*** 0,25 0,25 0,25 Triethylene glycol monomethyl ether 1,67 1,7 1,72 Defoamers 0,001 0,001 0,001 0,001 0,001 0,001 sum 100 100 100 100 100 100 The components used in the additive mixture have the following effect: * Tolyltriazole as an inhibitor against non-ferrous metal corrosion ** Antioxidant to prevent / reduce the oxidation of the alkylene glycol ethers *** Mixture of fatty alcohol ethoxylates **** Coolant composition based on monoethylene glycol / water (60 / 40 w / w) according to EP 1399523 B1, Example 5 For comparison. Nr 14 15 16 17 18 19 20 (cf.) Removal mg / cm 2< mg / cm 2< mg / cm 2< mg / cm 2< mg / cm 2< mg / cm 2< mg / cm 2< Cu -0,69 -0,17 -0,18 -0,80 -0,59 -0,30 -0,07 Soft solder -2,58 -0,17 -0,21 -0,23 -2,23 -0,26 -1,70 Brass -0,83 -0,03 -0,05 -0,13 -0,77 -0,01 -0,13 Steel -6,11 0,00 -0,01 -0,01 14,39 0,00 -37,65 Grey cast iron -5,80 0,07 0,08 0,09 -3,70 0,12 -48,79 Al -1,72 0,05 0,03 0,57 -0,46 0,05 -0,03

[0123] From the above table it can be seen that the N-octyldiethanolamine which is particularly preferred according to the invention shows particular advantages as an inhibitor of the corrosion of ferrous materials, especially steel and grey cast iron.

[0124] It also acts as a non-ferrous metal corrosion inhibitor and can partially replace the conventionally used tolyltriazole.

[0125] Corrosion test of composition number 15 was conducted according to ASTM D1384 with the following modifications: distilled water was used, diluted to a 50 wt% aqueous solution, and only three metals (brass, steel, and aluminum) considered representative for fuel cells were used. The corrosion test results were determined after 4 and 7 days, respectively. Nr 15 15 days 4 7 Removal mg / cm 2< mg / cm 2< Brass 0,01 -0,07 Steel 0,00 -0,01 Al 0,10 0,09

[0126] Development of electrical conductivity at different temperatures and addition of bidistilled water with a conductivity of 0.8 µS / cm at 25 °C and 1.5 µS / cm at 60 °C. Wt% Composition Ex. 15 Wt% water Conductivity µS / cm at 25 °C Conductivity µS / cm at 60 °C 100 0 0,8 1,3 99 1 1,0 1,9 98 2 1,2 2,4 97 3 1,5 3,0 96 4 1,7 3,7 95 5 2,0 4,4 90 10 3,4 9,0 80 20 7,5 22,4 70 30 13,7 38,0 60 40 19,2 50,4 50 50 24,7 63,2

[0127] It can be seen that the measured composition according to the invention from Example 15 remains below the critical conductivity of 25 µS / cm even when diluted 1:1 with bidistilled water at 25 °C and below a critical conductivity of 10 µS / cm when 20 wt% bidistilled water is added.

Claims

1. The use of a substantially water-free composition comprising (A) at least one alkylene glycol derivative of formula (I) where R1 is hydrogen or C1- to C4-alkyl, preferably hydrogen, methyl or ethyl, particularly preferably hydrogen or methyl and very particularly preferably hydrogen, R2 is C1- to C4-alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or n-butyl and very particularly preferably methyl, R3 is hydrogen or methyl, preferably hydrogen, and n is on arithmetic average a number from 3.0 to 4.0 and (B) at least one corrosion inhibitor selected from the group consisting of (Ba) orthosilicate esters and / or alkoxyalkylsilanes (Bb) azole derivatives (Bc) compounds of general formula (II) where R4 is an organic radical having 6 to 10 carbon atoms, in particular a straight-chain or branched, preferably straight-chain, alkyl or alkenyl radical having 6 to 10 carbon atoms, preferably 7 to 9 and particularly preferably 8 carbon atoms, p and q are independently of one another a positive integer from 1 to 30, preferably 1 to 20, particularly preferably 1 to 10, very particularly preferably 1 to 5 and in particular 1 to 3, especially 1 or 2, and each Xi for i = 1 to p and 1 to q are independently of one another selected from the group consisting of -CH2-CH2-O-, -CH2-CH(CH3)-O-, -CH(CH3)-CH2-O-, -CH2-C(CH3)2-O-, -C (CH3)2-CH2-O-, -CH2-CH(C2H5)-O-, -CH (C2H5)-CH2-O-, - CH(CH3)-CH(CH3)-O-, -CH2-CH2-CH2-O- and -CH2-CH2-CH2-CH2-O-, preferably selected from the group consisting of -CH2-CH2-O-, -CH2-CH(CH3)-O- and -CH(CH3)-CH2-O-, particularly preferably are -CH2-CH2-O-, bedeuten, with the proviso that the composition - comprises less than 1 wt% of water, preferably less than 0.75, particularly preferably less than 0.5, very particularly preferably less than 0.4, in particular less than 0.3 and especially less than 0.2 wt%, - comprises a proportion of alkylene glycol derivatives of formula (I) where n ≤ 2 of not more than 10 wt%, preferably not more than 8, particularly preferably not more than 6, very particularly preferably not more than 5, in particular not more than 4 and especially not more than 3 wt%, - comprises a proportion of alkylene glycol derivatives of formula (I) where n ≥ 5 of not more than 5 wt%, preferably not more than 4, particularly preferably not more than 3, very particularly preferably not more than 2.5 and especially not more than 2 wt%, - comprises a proportion of monoethylene glycol, diethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propylene glycol and glycerol of in each case not more than 10 wt%, preferably not more than 8, particularly preferably not more than 6, very particularly preferably not more than 5 and especially not more than 3 wt%, wherein it has an electrical conductivity according to ASTM D 1125 at 25°C of at most 50 µS / cm, preferably not more than 25, particularly preferably not more than 15, very particularly preferably not more than 10 and in particular not more than 5 µS / cm without further dilution with water as coolant and antifreeze for cooling systems in fuel cells, batteries and / or rechargeable batteries.

2. The use according to claim 1, wherein the electrical conductivity is substantially achieved by eschewing compounds in salt form and easily dissociating compounds.

3. The use according to any of the preceding claims, wherein the composition has a kinematic viscosity at 100°C according to ASTM D445 of at most 4 mm2 / s.

4. The use according to any of the preceding claims, wherein the composition has a kinematic viscosity at minus 40°C according to ASTM D445 of not more than 600 mm2 / s.

5. The use according to any of the preceding claims, wherein the structural element R3-N< is derived from amines selected from the group consisting of n-hexylamine, 2-methylpentylamine, n-heptylamine, 2-heptylamine, iso-heptylamine, 1-methylhexylamine, n-octylamine, 2-ethylhexylamine, 2-aminooctane, 6-methyl-2-heptylamine, n-nonylamine, iso-nonylamine, n-decylamine and 2-propylheptylamine or mixtures thereof.

6. The use according to any of claims 1 to 5, wherein the azole derivative is selected from the group consisting of benzimidazole, benzotriazole, tolyltriazole and / or hydrogenated tolyltriazole.

7. The use according to any of the preceding claims, wherein the composition comprises 95 to 99.9 wt% of component (A) and 0.1 to 5 wt% of component (B).

8. The use according to any of the preceding claims, wherein the ratio of the alkylene glycol derivatives of formula (I) where n = 3 to those where n = 4 is from 100 : 0 to 40 : 60.

9. The use according to any of the preceding claims, wherein the composition consists of component (A), component (B), optionally at least one further corrosion inhibitor (C) distinct from component (B) and optionally at least one further compound selected from the group consisting of bitterants, dyes, defoamers and antioxidants.

10. The use of a composition according to any of claims 1 to 9 without further dilution with water as a coolant for lithium-ion rechargeable batteries.

11. A method for operating a cooling system in electric vehicles having fuel cells and / or batteries and / or in hybrid vehicles composed of electric vehicles having fuel cells and / or batteries with internal combustion engines, preferably in motor vehicles, particularly preferably in passenger and commercial vehicles (so-called light- and heavy-duty vehicles) with a composition according to any of claims 1 to 9 without further dilution with water.

12. A method for cooling in which heat from a heat source at a relatively high temperature is transferred to a coolant via at least one first heat exchanger, this coolant is passed in a cooling circuit to at least one second heat exchanger and in said second heat exchanger heat is removed from the coolant at a relatively low temperature, wherein - the coolant employed is a composition according to any of claims 1 to 9 without further dilution with water, - the relatively high temperature is from 60°C to 300°C, - the relatively low temperature is from minus 50°C to 100°C, - the relatively low temperature is at least 50°C lower than the relatively high temperature.