New antifreeze agents and coolants for fuel cells, storage batteries and batteries

Abstract

To provide those usable as coolants and antifreeze agents for cooling systems.SOLUTION: A ready-to-use antifreeze composition for cooling systems contains: (A) at least one alkylene glycol derivative of formula (I); and (B) at least one corrosion inhibitor selected from the group consisting of (Bb) azole derivatives selected from the group consisting of benzotriazole, tolyltriazole and / or hydrogenated tolyltriazole, and (Bc) compounds of general formula (II).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a novel essentially anhydrous antifreeze for cooling systems, i.e. which can be used as a coolant and antifreeze without further dilution with water, and to its use in cooling systems in electric vehicles comprising fuel cells and / or batteries and / or in hybrid vehicles from electric vehicles comprising fuel cells and / or batteries together with an internal combustion engine, preferably in motor vehicles, particularly preferably in passenger cars and commercial vehicles (so-called light and heavy vehicles). [Background technology]

[0002] Fuel cells and / or batteries for mobile applications, especially in automobiles, must be able to operate even at low outside temperatures, for example down to about minus 40° C. A frost-proof coolant circuit is therefore essential.

[0003] Furthermore, when fast charging the battery, the temperature can reach over 100°C and the heat must be removed to prevent damage to the individual components.

[0004] The use of conventional cooler protection agents based on monoalkylene glycols, optionally with glycerin, used in internal combustion engines is not possible in the case of fuel cells and / or batteries without a complete electrical insulation of the cooling paths, because these agents, due to the salts and ionizable compounds contained therein as corrosion inhibitors, have too high an electrical conductivity, which can adversely affect the functioning of the fuel cell or battery. Furthermore, in the case of an accident, for example involving a leaking battery, when the coolant shorts the anode and cathode, a short circuit and / or the generation of hydrogen gas by the electrolyte can occur, which brings about further possible dangers.

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

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

[0007] Additionally, the cooler protectant must retain its initial, often low, electrical conductivity over an extended period of time and not increase in conductivity due to various decomposition processes, often resulting in the formation of ions.

[0008] From EP 1 399 523 a coolant for fuel cells is known which is based on water / monoethylene glycol and contains an azole derivative as inhibitor and optionally an orthosilicate ester.

[0009] Due to the substantial presence of water in conventional cooling protection fluids, the operating temperature of the cooling protection fluid is limited to the boiling point of water in the respective mixture at the operating pressure. Thus, a typical conventional cooling protection fluid mixture of water and monoethylene glycol usually boils at about 110-120°C at standard pressure.

[0010] In the prior art, anhydrous coolant concentrates are widely described, for example in US8394287, in which a cooler protection agent, often monoethylene glycol, is mixed with various additives, such as corrosion inhibitors, antioxidants, antifoaming agents, bittering agents and dyes. US8394287 describes the presence of at least one further cooler protection component, such as monopropylene glycol, higher ethylene glycol homologues or glycerin, in addition to the concentrate.

[0011] The purpose of these coolant concentrates is always to be subsequently diluted with water for use as a coolant (often with a water content of 30-70% by volume), and it is not envisaged to use the undiluted concentrate as a coolant.

[0012] So-called super concentrates are also often described, which are essentially highly concentrated formulations of the above additives in a relatively small amount of cooler protection components, often monoethylene glycol or monopropylene glycol.

[0013] The purpose of this super concentrate is always to produce a coolant concentrate from which it is subsequently diluted with cooler protection components to produce the actual coolant. Use of the undiluted super concentrate as a coolant is not envisaged.

[0014] Since monoethylene glycol boils at 197° C. at standard pressure, compositions containing monoethylene glycol have significant vapor pressure from a temperature of about 170° C., which limits their use as heat transfer fluids at high temperatures. The same applies to monoethylene glycol monomethyl ether (boiling point 124° C. at standard pressure) and monopropylene glycol (boiling point 188° C. at standard pressure).

[0015] Although glycerin as a component of the cooling device protection liquid does have a relatively high boiling point of about 290°C, it decomposes at that time. Therefore, glycerin at high temperatures is prone to decomposition reactions, and therefore is not very suitable as a heat transfer liquid under such conditions.

[0016] Thus, the lower alkylene glycols, particularly monoalkylene glycols, and their ethers, and glycerin, which are often used in water and cooler protection fluids, have significant drawbacks for use as heat transfer fluids at high temperatures.

[0017] If heat is to be transferred at relatively high temperatures, it is necessary either to design the cooling system for relatively high pressures or to switch to oils as coolants, such as mineral oils, synthetic oils or fatty acid esters, or fluorinated hydrocarbons. The former are technically complicated, since the cooling system is usually open to the environment. The latter have the disadvantage, among other things, that they have a small heat capacity and, if water enters due to the open configuration of the cooling system, form two phases due to their low compatibility with water. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] US Patent Application Publication No. 2015 / 266370 [Patent Document 2] International Publication No. 1995 / 07323 [Patent Document 3] European Patent No. 1399523 [Patent Document 4] U.S. Patent No. 8,394,287 Summary of the Invention [Problem to be solved by the invention]

[0019] The problem is therefore to develop a coolant for use in batteries or fuel cells in electric vehicles and / or in hybrid vehicles from electric vehicles comprising a fuel cell and / or a battery together with an internal combustion engine, which can be used at high temperatures and in so doing has a high heat capacity, is suitable for use in open cooling systems and is compatible with water.

[0020] Furthermore, they should also have low conductivity and this should be maintained during operation, which requires particularly low corrosion, since corrosion means that ions get into the coolant, which can increase electrical conductivity. [Means for solving the problem]

[0021] The object of the present invention is to provide a ready-to-use antifreeze agent for cooling systems, comprising: (A) at least one alkylene glycol derivative of formula (I) [ka] [In the formula, R 1 is hydrogen or C1-C4-alkyl, preferably hydrogen, methyl or ethyl, particularly preferably hydrogen or methyl and very particularly preferably hydrogen, R 2 is C1-C4-alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or n-butyl and very particularly preferably methyl, R 3 is hydrogen or methyl, preferably hydrogen, and n is the arithmetic mean, a number between 3.0 and 4.0. and (B) at least one corrosion inhibitor selected from the group consisting of: (Ba) Orthosilicate ester and / or alkoxyalkylsilane (Bb) Azole derivatives (Bc) Compound of general formula (II) [ka] [In the formula, R 4 is an organic radical having 6 to 10 carbon atoms, in particular a linear or branched, preferably linear, alkyl or alkenyl radical having 6 to 10 carbon atoms, preferably 7 to 9 and particularly preferably 8 carbon atoms, p and q are each independently a positive integer from 1 to 30, preferably from 1 to 20, particularly preferably from 1 to 10, very particularly preferably from 1 to 5 and in particular from 1 to 3, in particular 1 or 2, and Each X iare, for i=1 to p and 1 to q, independently 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 -CH2-CH2-O-. wherein the composition comprises: contains less than 1% by weight, preferably less than 0.75% by weight, particularly preferably less than 0.5% by weight, very particularly preferably less than 0.4% by weight, in particular less than 0.3% by weight and in particular less than 0.2% by weight of water, contains at most 10% by weight, preferably at most 8% by weight, particularly preferably at most 6% by weight, very particularly preferably at most 5% by weight, in particular at most 4% by weight and in particular at most 3% by weight of alkylene glycol derivatives of the formula (I) where n≦2, contains at most 5% by weight, preferably at most 4% by weight, particularly preferably at most 3% by weight, very particularly preferably at most 2.5% by weight and in particular at most 2% by weight of alkylene glycol derivatives of formula (I) where n≧5, containing monoethylene glycol, diethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propylene glycol and glycerol in a proportion of less than or equal to 10% by weight, preferably less than or equal to 8% by weight, particularly preferably less than or equal to 6% by weight, very particularly preferably less than or equal to 5% by weight and in particular less than or equal to 3% by weight, The problem was solved by the antifreeze.

[0022] The individual components are described in more detail below: Component (A) At least one alkylene glycol derivative of formula (I) [ka] In R 1 is hydrogen or C1-C4-alkyl, preferably hydrogen, methyl or ethyl, particularly preferably hydrogen or methyl and very particularly preferably hydrogen, R 2 is C1-C4-alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or n-butyl and very particularly preferably methyl, R 3 is hydrogen or methyl, preferably hydrogen, and n is the arithmetic mean and is a number between 3.0 and 4.0.

[0023] 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 It is.

[0024] In this regard, ethylene glycol ether is preferred over propylene glycol ether.

[0025] Additionally, monoalkyl ethers are preferred over dialkyl ethers.

[0026] Preferably, component (A) is an essentially pure compound of formula (I) with n=3 or a mixture of compounds of formula (I) with n=3 and n=4. For the compounds of formula (I) in the mixture, n is preferably 3.0 to 3.6, particularly preferably 3.0 to 3.5, very particularly preferably 3.05 to 3.4, in particular 3.1 to 3.3 and in particular 3.15 to 3.25, in arithmetic average.

[0027] In this case, for the compound in the mixture, R 1 Groups and R 2 The groups may be the same or different, preferably they are the same.

[0028] "Essentially pure" indicates that the compound of formula (I) where n=3 or n=4 also contains up to a specified proportion of homologous compounds having higher and lower values ​​for n.

[0029] Typically, in the case of compounds of formula (I) where n=3, the purity 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 in particular at least 97.5% by weight. The remainder is mainly compounds of formula (I) where n=2 and n=4.

[0030] In contrast, in the case of compounds of formula (I) where n=4, the purity is often only more than 50% by weight, preferably at least 55, particularly preferably at least 60% by weight. The remainder is mainly compounds of formula (I) where n=3 and to a lesser extent n=5.

[0031] Preferred components (A) as essentially pure compounds are Triethylene glycol monomethyl ether Triethylene glycol monoethyl ether Triethylene glycol mono-n-butyl ether It is.

[0032] Preferred components (A) in the mixture of compounds of formula (I) where n=3 and n=4 are A mixture of triethylene glycol monomethyl ether and tetraethylene glycol monomethyl ether, A mixture of triethylene glycol monoethyl ether and tetraethylene glycol monoethyl ether, Mixture of triethylene glycol mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether It is.

[0033] Less preferred, but different R 1 Mixtures of compounds of formula (I) having the group, n=3 and n=4 are also contemplated.

[0034] Such mixtures are A mixture of triethylene glycol monomethyl ether and tetraethylene glycol monoethyl ether A mixture of triethylene glycol monomethyl ether and tetraethylene glycol mono-n-butyl ether A mixture of triethylene glycol monoethyl ether and tetraethylene glycol monomethyl ether A mixture of triethylene glycol monoethyl ether and tetraethylene glycol mono-n-butyl ether A mixture of triethylene glycol mono-n-butyl ether and tetraethylene glycol monomethyl ether A mixture of triethylene glycol mono-n-butyl ether and tetraethylene glycol monoethyl ether It is.

[0035] Less preferably, for each n, R 3 may be independently the same or different from one another, i.e., mixed alkylene glycol derivatives of formula (I) from mixtures of ethylene oxide and propylene oxide are also contemplated.

[0036] In the case of mixtures of compounds of formula (I) with 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 in particular from 85:15 to 75:25.

[0037] Ingredient (B) Component (B) is (Ba) orthosilicate ester and / or alkoxysilane, (Bb) Azole derivatives, and (Bc) Compound of general formula (II) [ka] and at least one corrosion inhibitor selected from the group consisting of:

[0038] Orthosilicate (Ba) has the formula Si(OR 5 )4 wherein R 5 are each an organic group having 1 to 6 carbon atoms, preferably a linear or branched, preferably linear, alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 carbon atoms, particularly preferably an alkyl group having 1 to 4 carbon atoms, very particularly preferably an alkyl group having 1 or 2 carbon atoms.

[0039] An example of this is: Orthosilicic acid tetramethyl ester Orthosilicic acid tetraethyl ester Orthosilicic acid tetra-n-butyl ester Orthosilicate Tetraphenyl Ester Preferably, Orthosilicic acid tetramethyl ester Orthosilicic acid tetraethyl ester Particularly preferably, Orthosilicic acid tetraethyl ester It is.

[0040] The alkoxysilanes which are less preferred than the orthosilicate esters are preferably triethoxymethylsilane, diethoxydimethylsilane, ethoxytrimethylsilane, trimethoxymethylsilane, dimethoxydimethylsilane and methoxytrimethylsilane.

[0041] Within the scope of this specification, azole derivatives (Bb) are 5-membered heterocyclic compounds having 2 or 3 heteroatoms from the group of nitrogen and sulfur, containing none or at most one sulfur atom in the ring, and which may optionally have aromatic or aliphatic 6-membered ring fusions.

[0042] These five-membered heterocyclic compounds (azole derivatives) usually contain two N atoms and no S atoms, three N atoms and no S atoms, or one N atom and one S atom as heteroatoms.

[0043] A preferred group of said azole derivatives are the fused imidazoles and fused 1,2,3-triazoles, which have the general formula [ka] or [ka] wherein the variable R is hydrogen or C1-C 10 - an alkyl group, in particular methyl or ethyl, and the variable X is a nitrogen atom or a CH moiety.

[0044] Typical and preferred examples of the azole derivatives of general formula (III) are benzimidazole (X=CH, R=H), benzotriazole (X=N, R=H) and tolutriazole (X=N, R=CH3). A typical example of the azole derivatives of general formula (IV) is hydrogenated 1,2,3-tolutriazole (X=N, R=CH3).

[0045] A further preferred group of the above azole derivatives is represented by the general formula (V): [ka] wherein: The variable R has the meaning given above, and Variable R' is hydrogen, C1 to C 10 - an alkyl group, especially methyl or ethyl, or especially a mercapto group (-SH). Less preferably, R' is a group of the formula -(C m H 2m)-COOR″, where m is a number from 1 to 4, and R″ is a C1 to C 10 - alkyl, especially methyl or ethyl, or C6-C 12 -aryl. Examples for this are (2-benzothiazylthio)-acetic acid esters, or 3-(2-benzothiazylthio)propionic acid esters. A typical example for an azole derivative of general formula (V) is 2-mercaptobenzothiazole.

[0046] Furthermore, the general formula (VI) [ka] wherein the variables X and Y are both two nitrogen atoms or one nitrogen atom and one CH moiety. Preferred are non-fused azole derivatives of the formula: such as 1H-1,2,4-triazole (X=Y=N) or preferably imidazole (X=N, Y=CH).

[0047] For the present invention, very particular preference is given to benzimidazole, benzotriazole, tolyltriazole, hydrogenated tolyltriazole or mixtures thereof, in particular benzotriazole or tolyltriazole, especially tolyltriazole, as azole derivatives.

[0048] The abovementioned azole derivatives are commercially available or can be prepared by conventional methods. Hydrogenated benzotriazoles, such as hydrogenated tolyltriazole, are also available according to DE-A 1948 794 and are also commercially available.

[0049] In the general formula (II) of component (Bc), R 4 is an organic radical having 6 to 10 carbon atoms, in particular a linear or branched, preferably linear, alkyl or alkenyl radical having 6 to 10 carbon atoms, preferably 7 to 9 and particularly preferably 8 carbon atoms, p and q are each independently a positive integer from 1 to 30, preferably from 1 to 20, particularly preferably from 1 to 10, very particularly preferably from 1 to 5, in particular from 1 to 3, in particular 1 or 2, and Each X i are, for i=1 to p and 1 to q, 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 -CH2-CH2-O-.

[0050] In the compounds of formula (II), the structural element R 4 --N< is preferably derived from fatty amines, preferably obtained by hydrogenation and amination of fatty acids and esters, particularly preferably by hydrogenation and amination of the abovementioned fatty acids or by amination of fatty alcohols.

[0051] R 4 As groups, alkyl groups are preferred over alkenyl groups.

[0052] In a particular embodiment, p and q are independently of one another 1, 2 or 3, particularly preferably 1 or 2 and very particularly preferably 1.

[0053] In a preferred embodiment, the fatty amine is n-hexylamine, 2-methylpentylamine, n-heptylamine, 2-heptylamine, isoheptylamine, 1-methylhexylamine, n-octylamine, 2-ethylhexylamine, 2-aminooctane, 6-methyl-2-heptylamine, n-nonylamine, isononylamine, n-decylamine and 2-propylheptylamine, or mixtures thereof.

[0054] Particular preference is given to n-hexylamine, n-octylamine, 2-ethylhexylamine and n-decylamine, very particular preference to n-octylamine and 2-ethylhexylamine, and especially n-octylamine.

[0055] Particularly preferred are 2-, 3-, 4-, 5- and 6-tuply ethoxylated n-octylamines and mixtures thereof, and 2-, 3-, 4-, 5- and 6-tuply ethoxylated n-hexylamines and mixtures thereof.

[0056] For alkoxylated amines of general formula (II), the degree of alkoxylation relates to the sum of (p+q), i.e., the average total number of alkoxylated units per amine molecule.

[0057] Compound (II) is preferably a corresponding amine R 4 This is obtained by reacting -NH2 with alkylene oxides to the desired average statistical degree of alkoxylation, preferably under basic conditions. i is particularly preferred when is derived from ethylene oxide or propylene oxide, preferably from ethylene oxide.

[0058] The composition according to the invention typically comprises: Component (A): 95 to 99.9% by weight, preferably 96 to 99.8, particularly preferably 97 to 99.5, very particularly preferably 97.5 to 99% by weight, and in particular 98 to 99% by weight. Component (B): 0.1 to 5% by weight, preferably 0.2 to 4, particularly preferably 0.5 to 3, very particularly preferably 1 to 2.5% by weight, and in particular 1 to 2% by weight. Contains:

[0059] Component (C) - Further optional corrosion inhibitors Besides at least one above-mentioned component (B) as the essential corrosion inhibitor, the composition according to the invention may optionally contain at least one further corrosion inhibitor other than those described under (B).

[0060] However, preferred embodiments of the present invention do not contain any additional corrosion inhibitors (C) in the composition besides the above listed component (B).

[0061] 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).

[0062] The amine (C) advantageously has 2 to 9, in particular 4 to 8 carbon atoms. The amine (C) is advantageously a tertiary amine. The amine (C) advantageously contains 0 to 3 ether oxygen atoms or 0 to 3, preferably 0 to 2 hydroxyl groups. Typical examples for amine (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. The aliphatic and cycloaliphatic amines (C) are usually saturated.

[0063] Furthermore, the use of fatty acid alkoxylates and fatty alcohol alkoxylates as further corrosion inhibitors is contemplated, for example as compounds of formula (V) and (VI) as described in WO 18 / 95759, page 5, line 34 to page 10, line 10, which are incorporated herein by reference.

[0064] Component (C) is optional and can be present in the composition according to the invention in an amount of 0 to 2% by weight, preferably 0 to 1.5% by weight, particularly preferably 0 to 1% by weight and very particularly preferably 0 to 0.7% by weight.

[0065] In an obviously preferred embodiment, component (C) is absent.

[0066] Component (D) - Further Additives The composition according to the invention comprises (Da) Bittering agent (Db) Dye (Dc) Defoaming agent (Dd) antioxidants, and (De) Emulsifier The composition may further comprise at least one optional additional additive selected from the group consisting of:

[0067] Bittering agents (Da) may be added on the basis of hygiene and safety in case of ingestion, for example bittering agents of the denatonium benzoate type. Bittering agents are optional in the compositions according to the present application. Preferably, no bittering agents are present in the compositions according to the present invention.

[0068] These substances are commercially available and conventional compounds from the prior art that can typically be used in coolants.

[0069] The function of the emulsifier (De) used in the composition according to the invention is that it is capable of emulsifying potential impurities and / or assembly liquids originating from the cooling system, such as oligomers of polyalkylene glycols or glycerin, in the composition.

[0070] The components (D) are each optional and may each be present in the composition according to the invention independently of one another in an amount of 0 to 0.5% by weight, preferably 0.001 to 0.3% by weight, and particularly preferably 0.002 to 0.2% by weight.

[0071] Properties of the composition according to the invention The composition according to the invention is subject to the following conditions: They contain less than 1% by weight of water, preferably less than 0.75% by weight, particularly preferably less than 0.5% by weight, very particularly preferably less than 0.4% by weight, in particular less than 0.3% by weight and in particular less than 0.2% by weight.

[0072] The low water content according to the invention, together with the selection of component (A), leads to the increased boiling point according to the invention, since a higher water content limits the boiling point of the composition to about 100° C.+ the possible boiling point rise. Already with the presence of small amounts of water the boiling point of the composition is dramatically reduced, this effect is known for example from brake fluids, and different requirements for the boiling point arise depending on the water content.

[0073] Furthermore, when the composition is used as a coolant for cooling systems in fuel cells, accumulators and / or batteries, water having significant electrical conductivity can lead to electrolysis of the composition and the generation of undesirable hydrogen, which increases the risk of accidents.

[0074] A further provision of the composition according to the invention is that it contains at most 10% by weight, preferably at most 8% by weight, particularly preferably at most 6% by weight, very particularly preferably at most 5% by weight, in particular at most 4% by weight and in particular at most 3% by weight of alkylene glycol derivatives of formula (I) where n≦2.

[0075] A higher proportion of alkylene glycol derivatives of formula (I) with n≦2 leads, on the one hand, to an undesirable decrease in boiling point and, on the other hand, to a significant decrease in the viscosity of the composition. Too low a viscosity may be undesirable in certain applications, since a low-viscosity liquid may easily overcome seals and thus cause leaks.

[0076] A further provision of the composition according to the invention is that it contains at most 5% by weight, preferably at most 4% by weight, particularly preferably at most 3% by weight, very particularly preferably at most 2.5% by weight and in particular at most 2% by weight of alkylene glycol derivatives of formula (I) where n≧5.

[0077] Conversely, it is the case here that higher homologues bring about high viscosity of composition, and thus the pumpability of composition is hindered.High viscosity requires increased pump power, and thus requires increased energy consumption of pump.Moreover, higher homologues also have increased boiling point, so that there is a risk that they will precipitate out of composition at low temperatures.

[0078] A further provision of the composition according to the invention is that it contains monoethylene glycol, diethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propylene glycol and glycerin in a proportion of less than 10% by weight, preferably less than 8% by weight, particularly preferably less than 6% by weight, very particularly preferably less than 5% by weight and in particular less than 3% by weight, respectively.

[0079] In addition to the above-mentioned low boiling points of the lower homologues, polyhydric alcohols are relatively unstable to thermal stress and oxidation, so a low proportion of said compounds increases the stability of the composition according to the invention.

[0080] The composition according to the invention preferably has a specific heat capacity at 50° C. of at least 2.0 kJ / kg·K, particularly preferably at least 2.1 kJ / kg·K, very particularly preferably at least 2.2 kJ / kg·K and in particular at least 2.3 kJ / kg·K.

[0081] The composition according to the invention preferably has a thermal conductivity of at least 0.15 W / m·K.

[0082] To obtain a low conductivity, component (A) is preferably 50 C m 2 / V or less, and 45C·m is especially preferable. 2 / V or less, particularly preferably 40 C·m 2 / V or less, especially 35C m 2 / V or less, and especially 30C·m 2 Compounds with polarizabilities of 0.1 V or less are used.

[0083] use An advantage of the above composition is that it can be used as a coolant for cooling systems in general, in particular as cooling systems in fuel cells, accumulators and / or batteries. These coolants furthermore exhibit antifreeze action.

[0084] For the latter use, it is important that the composition has an electrical conductivity at 25° C. of a maximum of 50 μS / cm, preferably less than or equal to 25 μS / cm, particularly preferably less than or equal to 15, very particularly preferably less than or equal to 10 μS / cm and in particular less than or equal to 5 μS / cm.

[0085] Low electrical conductivity in the cooling systems of fuel cells, accumulators and batteries is essential because otherwise individual cells may short circuit on charging or discharging during operation.

[0086] Damage to the battery cells may result in contact between the coolant and the electrolyte, with the risk of the formation of dangerous hydrogen fluoride and other reaction products due to the reaction of the protic coolant with the commonly used electrolyte LiPF6. This risk is further enhanced by the presence of water, for example by the hygroscopic properties of the coolant (see below). For example, from AV Plakhotnyk et al., Journal of Fluorine Chemistry, 126 (2005) 27-31, it is known that for LiPF6 dissolved in an aprotic organic solvent, a total of about 10 mol % of the used LiPF6 is hydrolyzed already at a water content of 0.5% by mass over a period of about 23 days.

[0087] Surprisingly, no substantial reaction is observed when the composition of the invention is in contact with LiPF6, even in the presence of water, and the composition according to the invention is therefore particularly suitable for cooling lithium-ion accumulators.

[0088] The terms "battery" and "accumulator" are used herein in accordance with common usage, with accumulator being used to describe rechargeable, discrete or interconnected chemical energy stores, and "battery" being used generically for both rechargeable and non-rechargeable electrical storage devices. Thus, the term "accumulator" is a subset of "battery".

[0089] In order to achieve the requisite low electrical conductivity according to the invention, it is preferable to avoid compounds in the form of salts and compounds that dissociate easily, especially acids, in the components used.The above-mentioned further additives are therefore used in a preferred embodiment in essentially non-ionic form under the conditions of use.

[0090] 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 even during use in cooling systems, for example due to absorption of atmospheric moisture. This also applies during storage and use in closed systems, since many sealants are permeable to air and atmospheric moisture.

[0091] An advantage of the compositions according to the invention is that they have an electrical conductivity at 25° C. of less than 50 μS / cm, preferably less than 25 μS / cm, particularly preferably less than 15 μS / cm and very particularly preferably less than 10 μS / cm, even when absorbing or adding up to 5% by weight, preferably up to 10% by weight, particularly preferably up to 25% by weight, very particularly preferably up to 40% by weight and in particular up to 50% by weight of water, based on the entire mixture.

[0092] A further advantage of the compositions according to the invention is their compatibility with the most important commonly used sealing materials, for example EPDM (ethylene-propylene-diene-(monomer) rubber, preferably according to EN 13956), SBR (styrene-butadiene-rubber), FKM (fluorocarbon rubber, preferably according to DIN ISO 1629 or ASTM D 1418, e.g. Viton®), NBR (acrylonitrile butadiene rubber) and HNBR (hydrogenated acrylonitrile butadiene rubber).

[0093] The advantage of the compositions according to the invention is that, due to their stability against thermal loads and oxidation, the initial low electrical conductivity is retained even over time, since the formation of electrically conductive products due to decomposition or oxidation is reduced.

[0094] A particularly preferred embodiment of the invention is therefore to dilute the composition according to the invention with up to 40% by weight, or even up to 50% by weight, of ion-free, preferably desalted or double-distilled water, based on the total aqueous mixture, and use it in this form as a coolant and antifreeze for fuel cells, since this aqueous coolant and antifreeze also has a sufficiently low conductivity for this special application.

[0095] Here, "ion-free water" refers to water having a neutral pH value, in which ions other than hydroxide ions and oxonium ions from the autoprotonation of water are essentially absent. The electrical conductivity of such water at 25° C. is preferably 5 μS / cm or less, particularly preferably 3 μS / cm or less, very particularly preferably 2 μS / cm or less, and in particular 1 μS / cm or less.

[0096] The compositions according to the invention preferably have a boiling point at 1013 hPa (standard pressure) of at least 200°C, preferably at least 210°C, particularly preferably at least 220°C, very particularly preferably at least 230°C and in particular at least 250°C.

[0097] This results in the composition remaining liquid and functioning as a heat transfer medium even at high ambient temperatures without the vapor pressure in the composition becoming too high, thus allowing the composition according to the invention to be handled in open systems even at high temperatures.

[0098] As explained above, the composition according to the invention has an advantageous viscosity which is neither too low nor too high.

[0099] Preferably, up to 4 mm 2 / sec, particularly preferably up to 3 mm 2 / s, and especially preferably up to 2 mm 2 3 / sec at 100°C in accordance with ASTM D445.

[0100] Furthermore, preferably 600 mm 2 / sec or less, and especially preferably 500 mm 2 / sec or less, particularly preferably 400 mm 2 / sec or less, and especially 350 mm 2 The kinematic viscosity at -40°C in accordance with ASTM D445 is less than 1 / sec.

[0101] The advantage of the compositions according to the invention is that they exhibit, on the one hand, a lower viscosity and, on the other hand, less viscosity change over a wide temperature range, preferably from minus 40°C to plus 100°C, than conventional coolants based on water and monoethylene glycol.

[0102] For example, a mixture of 50% by weight water and 50% by weight monoethylene glycol is already solidified at about -37°C and therefore cannot be used in the preferred temperature ranges mentioned above. The kinetic viscosity of such a mixture is about 300 mmHg at -20°C. 2 / second.

[0103] An advantage of the present invention is that a typical mixture according to the present invention does not solidify at minus 40°C and has a kinematic viscosity of about 250 to 500 mm at minus 40°C. 2 / sec, and approximately 100 mm at -20°C 2 / sec or less.

[0104] Therefore, the change in kinetic viscosity in the temperature range from -40°C to +100°C is about 500 mm for the composition according to the present invention. 2 / sec or less, which is less variable than the above mixture of water and monoethylene glycol. This means that pumps with lower delivery power can be used in the cooling system, and therefore less energy has to be consumed to deliver the coolant through the cooling system.

[0105] method Due to the fact that the above-mentioned compositions have a higher boiling point than conventional coolants based on water or monoalkylene glycols, a further object of the present invention is a cooling method for vehicle storage batteries, fuel cells and batteries, which comprises transferring heat from a heat source at a relatively high temperature to a coolant via at least one first heat exchanger and directing this coolant in a cooling circuit to at least one second heat exchanger, where heat is removed from the coolant at a relatively low temperature, wherein: Use of the above-mentioned composition as a coolant, the relatively high temperature is 60 to 300°C, preferably 70 to 280°C, particularly preferably 80 to 250°C; the relatively low temperature is from minus 50 to 100°C, preferably from minus 40 to 90°C, particularly preferably from minus 30 to 80°C; the relatively low temperature is at least 50° C. lower than the relatively high temperature; This is the method.

[0106] In a preferred embodiment, when using compositions according to the invention having a high boiling point, the pressure in the cooling circuit is at most 500 hPa, preferably at most 400 hPa, particularly preferably at most 300 hPa and very particularly preferably at most 200 hPa above ambient pressure.

[0107] In this case, the higher temperatures are, for example, the wall temperatures of accumulators, fuel cells or batteries during normal operation of electric vehicles equipped with fuel cells and / or batteries and / or hybrid vehicles from electric vehicles equipped with fuel cells and / or batteries together with an internal combustion engine or during the charging and discharging processes of such accumulators or batteries.

[0108] Said lower temperature is then preferably the ambient temperature with which the warmed coolant comes into contact in the second heat exchanger.

[0109] All heat exchangers may be components known per se to those skilled in the art for this purpose.

[0110] All references in this specification to percentages, ppm or parts relate to weight percent, ppm or parts by weight unless otherwise stated. EXAMPLES

[0111] Test Method Unless otherwise stated, the values ​​reported herein were measured by 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 Sphere Gap Method Moisture 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 composition The following compositions were made (listed in weight percent): Comparison: [Table 1-1]

[0112] [Table 1-2]

[0113] [Table 1-3] *The two part additive mixture used consisted of the non-ferrous metal corrosion inhibitor tolyltoluazole, an antioxidant, and a fatty alcohol ethoxylate as a corrosion inhibitor dissolved in 1.67 parts of triethylene glycol monomethyl ether.

[0114] In the corrosion test, the reserve alkalinity (measured in a test volume of 0.1 M HCl / 10 ml) before and after corrosion, the pH value before and after corrosion, and the corrosion loss [mg / cm ] over a period of 336 h according to ASTM D1384 were recorded. 2 ] yielded the following values:

[0115] [Table 2-1]

[0116] [Table 2-2]

[0117] [Table 2-3]

[0118] In the supernatant from the corrosion test according to ASTM D1384, the following metal contents were determined by ICP spectrometry (inductively coupled plasma) [ppm]: [Table 3]

[0119] It can be seen that in the composition according to the invention, the uptake of especially iron ions into the liquid is significantly reduced, but also that of copper ions. It is therefore possible to keep the electrical conductivity of the composition according to the invention low. Moreover, the pH value remains stable throughout the corrosion and shows only slight changes.

[0120] This is shown by the following measured electrical conductivities (μS / cm at 25°C) before and after corrosion: [Table 4]

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

[0122] Corrosion testing according to ASTM D1384 and corrosion erosion over 4 weeks [mg / cm 2 ]: [Table 5]

[0123] The components used in the additive mixture have the following effects: * Tolyltriazole as an inhibitor against corrosion of non-ferrous metals **Antioxidants to prevent / reduce oxidation of alkylene glycol ethers *** Mixture of fatty alcohol ethoxylates ****Example 5 of EP1399523 B1, a coolant composition based on monoethylene glycol / water (60 / 40 w / w) for comparison.

[0124] [Table 6]

[0125] From the above table it can be seen that the N-octyldiethanolamine which is particularly preferred according to the invention shows particular advantages as corrosion inhibitor for ferrous materials, in particular steel and grey cast iron.

[0126] In addition, it also acts as a corrosion inhibitor for non-ferrous metals and can partially replace the conventionally used tolyltriazole.

[0127] Corrosion testing of composition No. 15 similar to ASTM D1384 with the following modifications: a 50% by weight aqueous solution in distilled water and using only three metals considered representative for fuel cells (brass, steel, and aluminum) was used. The corrosion test results were measured after 4 and 7 days.

[0128] [Table 7]

[0129] Changes in electrical conductivity at various temperatures and when mixed with double-distilled water having electrical conductivity of 0.8 μS / cm at 25°C or 1.5 μS / cm at 60°C.

[0130] [Table 8]

[0131] It can be seen that the measured composition according to the invention from Example 15 still remains below the critical conductivity of 25 μS / cm at 25° C. upon 1:1 dilution with double distilled water, and remains below the critical conductivity of 10 μS / cm in the case of a mixture of 20% by weight of double distilled water.

Claims

1. A ready-to-use antifreeze agent for cooling systems, comprising: (A) at least one alkylene glycol derivative of formula (I) 【Chemistry 1】 [In the formula, R 1 is hydrogen or C 1 ~C 4 alkyl, preferably hydrogen, methyl or ethyl, particularly preferably hydrogen or methyl and very particularly preferably hydrogen, R 2 is C 1 ~C 4 - alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or n-butyl and very particularly preferably methyl, R 3 is hydrogen or methyl, preferably hydrogen, and n is a number between 3.0 and 4.0 in arithmetic mean. and (B) at least one corrosion inhibitor selected from the group consisting of: (Ba) Orthosilicate ester and / or alkoxyalkylsilane (Bb) Azole derivative (Bc) Compound of general formula (II) 【Chemistry 2】 [In the formula, R 4 is an organic radical having 6 to 10 carbon atoms, in particular a linear or branched, preferably linear, 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 positive integers from 1 to 30, preferably from 1 to 20, particularly preferably from 1 to 10, very particularly preferably from 1 to 5 and in particular from 1 to 3, in particular 1 or 2, and Each X i For i=1 to p and 1 to q, each independently represents -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 -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3 )-O- and -CH(CH 3 )-CH 2 -O-, particularly preferably -CH 2 -CH 2 -O-. wherein the composition comprises: contains less than 1% by weight, preferably less than 0.75% by weight, particularly preferably less than 0.5% by weight, very particularly preferably less than 0.4% by weight, in particular less than 0.3% by weight and in particular less than 0.2% by weight of water, contains at most 10% by weight, preferably at most 8% by weight, particularly preferably at most 6% by weight, very particularly preferably at most 5% by weight, in particular at most 4% by weight and in particular at most 3% by weight of alkylene glycol derivatives of formula (I) where n≦2, contains at most 5% by weight, preferably at most 4% by weight, particularly preferably at most 3% by weight, very particularly preferably at most 2.5% by weight and in particular at most 2% by weight of alkylene glycol derivatives of formula (I) where n>5, containing monoethylene glycol, diethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propylene glycol and glycerin in a proportion of less than 10% by weight, preferably less than 8% by weight, particularly preferably less than 6% by weight, very particularly preferably less than 5% by weight and in particular less than 3% by weight, The antifreeze agent.

2. 2. The composition according to claim 1, characterized in that it has an electrical conductivity at 25° C. of a maximum of 50 μS / cm, preferably not more than 25 μS / cm, particularly preferably not more than 15 μS / cm, very particularly preferably not more than 10 μS / cm and in particular not more than 5 μS / cm.

3. 3. The composition according to claim 1 or 2, characterized in that it has a boiling point at 1013 hPa of at least 200 ° C, preferably at least 210 ° C, particularly preferably at least 220 ° C, very particularly preferably at least 230 ° C, and in particular at least 250 ° C.

4. Maximum 4mm according to ASTM D445 2 4. The composition according to claim 1, characterized in that it has a kinematic viscosity at 100° C. of 1 / s.

5. 600mm according to ASTM D445 2 5. The composition according to claim 1, characterized in that it has a kinematic viscosity at minus 40°C of less than or equal to 1 / sec.

6. 6. The composition according to claim 1, characterized in that it has a specific heat capacity at 50° C. of at least 2.0 kJ / kg·K.

7. 7. The composition according to claim 1, characterized in that it has a thermal conductivity of at least 0.15 W / mK.

8. Structural element R 3 8. The composition of claim 1, wherein -N< is derived from an amine selected from the group consisting of n-hexylamine, 2-methylpentylamine, n-heptylamine, 2-heptylamine, isoheptylamine, 1-methylhexylamine, n-octylamine, 2-ethylhexylamine, 2-aminooctane, 6-methyl-2-heptylamine, n-nonylamine, isononylamine, n-decylamine and 2-propylheptylamine, or mixtures thereof.

9. 8. The composition according to claim 1, wherein the azole derivative is selected from the group consisting of benzimidazole, benzotriazole, tolyltriazole and / or hydrogenated tolyltriazole.

10. 95 to 99.9% by weight of component (A), and 0.1 to 5% by weight of component (B) The composition according to any one of claims 1 to 9, comprising:

11. 11. The composition according to claim 1, characterized in that the ratio of alkylene glycol derivative of formula (I) where n=3: alkylene glycol derivative of formula (I) where n=4 is from 100:0 to 40:

60.

12. 12. The composition according to claim 1, comprising component (A), component (B), optionally at least one further corrosion inhibitor (C) different from component (B), and optionally at least one further compound selected from the group consisting of bittering agents, dyes, antifoaming agents and antioxidants.

13. 13. Use of a composition according to any one of claims 1 to 12 as a coolant and antifreeze agent for cooling systems in fuel cells, accumulators and / or batteries.

14. 13. Use of a composition according to any one of claims 1 to 12 as a coolant for a lithium-ion accumulator battery.

15. 13. Use of a composition according to any one of claims 1 to 12, containing up to 50% by weight of ion-free water, based on the total aqueous mixture, as a coolant and antifreeze for fuel cells.

16. 16. The use according to claim 15, characterized in that the aqueous mixture has an electrical conductivity at 25 ° C of less than or equal to 50 μS / cm, preferably less than or equal to 25 μS / cm, particularly preferably less than or equal to 15 μS / cm and very particularly preferably less than or equal to 10 μS / cm.

17. 1. A method of cooling by transferring heat from a heat source at a relatively high temperature through at least one first heat exchanger to a coolant and directing the coolant in a cooling circuit to at least one second heat exchanger where heat is removed from the coolant at a relatively low temperature, comprising: Use of a composition according to any one of claims 1 to 12 as a coolant, the relatively high temperature is between 60°C and 300°C; the relatively low temperature is between minus 50°C and 100°C; the relatively low temperature is at least 50° C. lower than the relatively high temperature; The cooling method according to claim 1,

Images