Novel coolant with low electrical conductivity

Abstract

This application describes a coolant having low electrical conductivity, a corresponding coolant concentrate, and the use of such a coolant in the cooling system of a vehicle equipped with an electric engine, a fuel cell, or a hybrid engine that combines a combustion engine with an electric engine or a combustion engine with a fuel cell.

Description

[Technical Field]

[0001] This application describes a coolant with low electrical conductivity, a corresponding coolant concentrate, and the use of such a coolant in the cooling system of a vehicle equipped with an electric engine, a fuel cell, or a hybrid engine that combines a combustion engine with an electric engine or a combustion engine with a fuel cell. [Background technology]

[0002] WO 02 / 101848 discloses a coolant containing an azole derivative and an orthosilicate for cooling a fuel cell-powered device. The coolant does not contain an acid or an amine, because this would increase its electrical conductivity. However, low electrical conductivity is crucial for such coolants to prevent short-circuiting of the electrodes and improve the safety characteristics of the cooling system.

[0003] The drawback is that such coolants, in order to maintain low electrical conductivity, do not contain alkaline components, which are necessary to neutralize acidic decomposition products that could otherwise cause corrosion.

[0004] WO 2018 / 095759 discloses a coolant for cooling a fuel cell-powered device, comprising an azole derivative, an orthosilicate and optionally an alkoxylated amine.

[0005] Alkoxylated amines are used as corrosion inhibitors against the corrosion of iron- or copper-containing alloys. The coolants disclosed do not contain carboxylic acids, because this would increase their electrical conductivity. Organic carboxylic acids, particularly sebacic acid and terephthalic acid, are known to be effective corrosion inhibitors for aluminum, copper, and brass. Therefore, coolants that do not contain organic carboxylic acids, which exhibit conductivity-increasing properties, usually lack good corrosion protection properties for these metals. Summary of the Invention

[0006] It was therefore an object of the present invention to provide coolants that exhibit a sufficiently low electrical conductivity so that the respective coolant is suitable for use in vehicles with electric drives.

[0007] The purpose of this is to (A) at least one glycol; (B) Water; (C) at least one azole derivative; (D) at least one ester of orthosilicic acid or an alkoxyalkylsilane; (E) at least one tertiary amine containing at least one 2-hydroxyethyl or 2-hydroxypropyl group; (F) at least one monocarboxylic acid; (G) at least one optional silicophosphonate; (H) At least one optional additional coolant additive. A coolant comprising: the molar ratio of the tertiary amine (E) to the monocarboxylic acid (F) is 1:0.1 to 1:0.6; This is achieved by the coolant wherein components (C)-(H) are present in amounts such that the coolant exhibits a conductivity of less than 100 μS / cm, preferably less than 50 μS / cm, more preferably less than 45 μS / cm.

[0008] Such coolants exhibit both low electrical conductivity and good corrosion protection properties, making them usable as coolants for electric drive vehicles. The presence of at least one monocarboxylic acid (F) typically increases the electrical conductivity of the coolant, but provides benefits in corrosion inhibition as the increased electrical conductivity is tolerated. The details of the components are as follows:

[0009] Glycol (A) As alkylene glycol component or derivative thereof (A), it is possible to use, in particular, monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and mixtures thereof, and also monopropylene glycol, dipropylene glycol and mixtures thereof, 1,3-propanediol, higher polyalkylene glycols, alkylene glycol ethers such as monoethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, monoethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, monoethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether or glycerol (in each case alone or mixtures thereof).

[0010] Water (B) The water used in the coolant according to the present invention should be ion-free, exhibiting a neutral pH value and being substantially free of ions other than hydroxide and hydronium ions from the autoprotolysis of the water at the respective temperature.

[0011] The conductivity of the ion-free water used at 25°C (determined in accordance with ASTM D 1125 throughout this specification) should preferably be 5 μS / cm or less, more preferably 3 μS / cm or less, even more preferably 2 μS / cm or less, especially 1 μS / cm or less.

[0012] The ion-free water used can be pure distilled or double-distilled water, or water that has been deionized, for example by ion exchange.

[0013] Azole derivatives (C) Azole derivatives in the context of the present invention mean five-membered heterocyclic compounds having two or three heteroatoms from the group consisting of nitrogen and sulfur, which may contain no sulfur atoms or at most one sulfur atom and may have an aromatic or saturated six-membered fused ring.

[0014] These five-membered heterocyclic compounds (azole derivatives) can generally 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.

[0015] A preferred group of azole derivatives identified are those of the general formula [ka] [In the formula, The variable R is hydrogen or C1-C 10 - an alkyl group, in particular methyl or ethyl, The variable group X is a nitrogen atom or a CH group. These are annelated imidazoles and annelated 1,2,3-triazoles.

[0016] Typical and preferred examples of the azole derivatives of general formula (I) are benzimidazole (X=CH, R=H), benzotriazole (X=N, R=H) and tolutriazole (X=N, R=CH). A typical example of the azole derivatives of general formula (II) is hydrogenated 1,2,3-tolutriazole (X=N, R=CH).

[0017] Another preferred group of azole derivatives identified is represented by the general formula (III) [ka] [In the formula, The variable R has the same meaning as above, The variable group R' is hydrogen, C1-C 10- an alkyl group, in particular methyl or ethyl, or in particular a mercapto group (-SH). A typical example of an azole derivative of general formula (III) is 2-mercaptobenzothiazole.

[0018] It is also possible, but less preferred, to use (2-benzothiazylthio)acetic acid (R' = -S-CH2-COOH) or (2-benzothiazylthio)propionic acid (R' = -S-CH2-CH2-COOH), as this embodiment is less preferred because the use of such free acid compounds increases the conductivity of the coolant.

[0019] Further suitable azole derivatives are those of the general formula (IV) [ka] wherein the variables X and Y together are two nitrogen atoms or one nitrogen atom and a CH group, e.g., 1H-1,2,4-triazole (X=Y=N), or preferably imidazole (X=N, Y=CH). It is a non-anenated azole derivative of

[0020] For the purposes of the present invention, benzimidazole, benzotriazole, tolutriazole, hydrogenated tolutriazole or mixtures thereof, in particular benzotriazole or tolutriazole, are very particularly preferred as azole derivatives.

[0021] The azole derivatives described are commercially available or can be prepared by conventional methods. Hydrogenated benzotriazoles, such as hydrogenated tolutriazole, are likewise available as described in DE-A 1 948 794 and are also commercially available.

[0022] Esters of orthosilicic acid or alkoxyalkylsilanes (D) Esters of orthosilicic acid have the formula Si(OR 1 )4 [In the formula, R 1 is an organic substituent containing 1 to 6 carbon atoms, for example, a linear or branched, preferably linear, alkyl substituent containing 1 to 6 carbon atoms, or an aromatic substituent containing 6 carbon atoms, more preferably an alkyl substituent containing 1 to 4 carbon atoms, and even more preferably an alkyl substituent containing 1 or 2 carbon atoms. is a compound of

[0023] Alkoxyalkylsilanes are less preferred, in which both the alkoxy and alkyl groups comprise straight or branched, preferably straight chain, alkyl substituents containing 1 to 6 carbon atoms, more preferably alkyl substituents containing 1 to 4 carbon atoms, and even more preferably alkyl substituents containing 1 or 2 carbon atoms.

[0024] Typical examples of compound (D) include tetraalkoxysilanes, preferably tetramethoxysilane and tetraethoxysilane, and alkoxyalkylsilanes, preferably triethoxymethylsilane, diethoxydimethylsilane, ethoxytrimethylsilane, trimethoxymethylsilane, dimethoxydimethylsilane, and methoxytrimethylsilane. Tetraalkoxysilanes are preferred, tetramethoxysilane and tetraethoxysilane are particularly preferred, and tetraethoxysilane is particularly preferred.

[0025] Compound (D) is primarily used as an inhibitor of aluminum corrosion.

[0026] Tertiary amine (E) At least one tertiary amine (E) contains at least one 2-hydroxyethyl or 2-hydroxypropyl group. Possible tertiary amines (E) may contain 1, 2 or 3 2-hydroxyethyl or 2-hydroxypropyl groups, preferably 2 or 3 2-hydroxyethyl or 2-hydroxypropyl groups, more preferably 2-hydroxyethyl groups.

[0027] Substituents of the tertiary amine (E) that are not 2-hydroxyethyl or 2-hydroxypropyl groups may be aliphatic, alicyclic or aromatic groups having up to 20 carbon atoms, preferably up to 18, more preferably up to 16, even more preferably up to 14 and especially up to 12 carbon atoms.

[0028] These substituents are preferably aliphatic or aromatic, more preferably aliphatic.

[0029] The aromatic substituent can be, for example, phenyl, tolyl, or naphthyl.

[0030] The aliphatic substituents can be linear or branched and are preferably linear alkyl substituents containing from 1 to 18 carbon atoms, preferably from 2 to 16, more preferably from 4 to 14, especially from 6 to 12 carbon atoms.

[0031] In the compounds (E), the substituents are preferably derived from aliphatic amines, which are preferably obtainable by hydrogenation and amination of fatty acids and esters, particularly preferably by hydrogenation and amination of: 2-ethylhexanoic acid, octanoic acid (caprylic acid), pelargonic acid (nonanoic acid), 2-propylheptanoic acid, decanoic acid (capric acid), undecanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid (myristic acid), pentadecanoic acid, palmitic acid (hexadecanoic acid), palmitoleic acid [(9Z)-hexadec-9-enoic acid], margaric acid (heptadecanoic acid), stearic acid (octadecanoic acid), oleic acid [( 9Z)-octadec-9-enoic acid], elaidic acid [(9E)-octadec-9-enoic acid], linoleic acid [(9Z,12Z)-octadeca-9,12-dienoic acid], linolenic acid [(9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid], eleostearic acid [(9Z,11E,13E)-octadeca-9,11,13-trienoic acid], ricinoleic acid ((R)-12-hydroxy-(Z)-octadec-9-enoic acid), isoricinoleic acid [(S)-9-hydroxy-(Z)-octadec-12-enoic acid], nonadecanoic acid, arachidic acid (eicosanoic acid), behenic acid (docosanoic acid), and erucic acid [(13Z)-docosa-13-enoic acid].

[0032] Examples of tertiary amines (E) containing one 2-hydroxyethyl or 2-hydroxypropyl group and two other substituents include those of the general formula (I): [ka] [In the formula, R 2 and R 3 are, independently of one another, the above-mentioned substituents, preferably linear or branched, preferably linear alkyl substituents, containing 1 to 18 carbon atoms, preferably 2 to 16, more preferably 4 to 14, in particular 6 to 12 carbon atoms, or may together form a 5- or 6-membered ring containing a nitrogen atom; X iis -CH2-CH2-O-, -CH2-CH(CH3)-O- or -CH(CH3)-CH2-O-, preferably -CH2-CH2-O-; n is a positive integer of 1 to 5, preferably 1 to 4, more preferably 1 to 3, even more preferably 1 or 2, and especially 1. Examples include:

[0033] Preferred individual compounds are dimethylethanolamine, dimethylpropanolamine, diethylethanolamine, diethylpropanolamine, di-n-butylethanolamine, di-n-butylpropanolamine, N-hydroxyethylpyrrolidine, N-hydroxyethylpiperidine and N-hydroxyethylmorpholine.

[0034] Examples of tertiary amines (E) containing two 2-hydroxyethyl or 2-hydroxypropyl groups and one other substituent include those of the general formula (II): [ka] [In the formula, R 4 is a substituent as defined above, preferably a linear or branched, preferably linear, alkyl substituent containing 1 to 18 carbon atoms, preferably 2 to 16, more preferably 4 to 14, especially 6 to 12 carbon atoms; For each X for i=1 to p and 1 to q i is independently selected from the group consisting of -CH2-CH2-O-, -CH2-CH(CH3)-O-, or -CH(CH3)-CH2-O-, preferably -CH2-CH2-O-; and p and q are each independently a positive integer of 1 to 5, preferably 1 to 4, more preferably 1 to 3, even more preferably 1 or 2, especially 1. Examples include:

[0035] Preferred individual compounds are those containing the substituent R 4and bis(2-hydroxyethyl)amine or bis(2-hydroxypropyl)amine containing 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 as the amine, or a mixture thereof.

[0036] Particularly preferred are bis(2-hydroxyethyl)-substituted n-hexylamines, n-octylamine, 2-ethylhexylamine and n-decylamine (especially preferred are n-octylamine and 2-ethylhexylamine), and in particular bis(2-hydroxyethyl)n-octylamine.

[0037] These compounds are reacted with the corresponding amine R 4 This can be obtained by reacting -NH with alkylene oxides to the desired average statistical degree of alkoxylation, preferably under basic conditions. i is particularly preferred when it is derived from ethylene oxide or propylene oxide, preferably ethylene oxide.

[0038] Examples of tertiary amines (E) containing three 2-hydroxyethyl or 2-hydroxypropyl groups include triethanolamine and tripropanolamine, preferably triethanolamine.

[0039] Preferred amines (E) are dimethylethanolamine, dimethylpropanolamine, diethylethanolamine, di-n-butylethanolamine, N-hydroxyethylmorpholine, bis(2-hydroxyethyl)n-hexylamine, bis(2-hydroxyethyl)n-octylamine, bis(2-hydroxyethyl)2-ethylhexylamine, bis(2-hydroxyethyl)n-decylamine and triethanolamine.

[0040] Monocarboxylic acid (F) Suitable monocarboxylic acids (F) may be linear or branched aliphatic, alicyclic or aromatic monocarboxylic acids having up to 20 carbon atoms, preferably 2 to 18, more preferably 5 to 16, even more preferably 5 to 14, most preferably 6 to 12, especially 8 to 10 carbon atoms.

[0041] Branched chain aliphatic monocarboxylic acids are preferred over the corresponding straight chain monocarboxylic acids.

[0042] Useful linear or branched aliphatic or cycloaliphatic monocarboxylic acids (F) are, for example, propionic acid, pentanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, 2,2-dimethylbutanoic acid, cyclohexylacetic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, decanoic acid, undecanoic acid or dodecanoic acid.

[0043] Suitable aromatic monocarboxylic acids (F) are, in particular, benzoic acid. Also useful are, for example, C1-C8-alkylbenzoic acids, such as o-, m-, p-methylbenzoic acid or p-tert-butylbenzoic acid, and hydroxyl-containing aromatic monocarboxylic acids, such as o-, m-, or p-hydroxybenzoic acid, o-, m-, or p-(hydroxymethyl)benzoic acid, or halobenzoic acids, such as o-, m-, or p-fluorobenzoic acid.

[0044] Particularly preferred are 2-ethylhexanoic acid and isononanoic acid.

[0045] As used herein, isononanoic acid refers to one or more branched aliphatic carboxylic acids having nine carbon atoms. Embodiments of isononanoic acid used in engine coolant compositions can include 7-methyloctanoic acid (e.g., CAS Nos. 693-19-6 and 26896-18-4), 6,6-dimethylheptanoic acid (e.g., CAS No. 15898-92-7), 3,5,5-trimethylhexanoic acid (e.g., CAS No. 3302-10-1), 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, 2,2,4,4-tetramethylpentanoic acid (e.g., CAS No. 3302-12-3), and combinations thereof. In a preferred embodiment, the isononanoic acid contains, as its major component, greater than 90% of one of 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, and 2,2,4,4-tetramethylpentanoic acid. The remainder of the isononanoic acid may include other 9-carbon carboxylic acid isomers and small amounts of one or more contaminants. In a preferred embodiment, the isononanoic acid contains, as its major component, greater than 90% 3,5,5-trimethylhexanoic acid, and even more preferably, the major component is greater than 95% 3,5,5-trimethylhexanoic acid.

[0046] In addition to or instead of monocarboxylic acid, it is possible to use carboxylic acid with higher functionality, such as dicarboxylic acid or tricarboxylic acid, but it is disadvantageous.The use of monocarboxylic acid has been shown to bring about better results compared with commonly used dicarboxylic acid.See examples.

[0047] When a dicarboxylic or tricarboxylic acid is used, it may be aliphatic, alicyclic or aromatic, preferably aliphatic or aromatic, more preferably aliphatic, having up to 20 carbon atoms, preferably up to 18, more preferably up to 16, even more preferably up to 14, especially up to 12 carbon atoms.

[0048] When a dicarboxylic acid is used, examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, alkyl or alkenyl succinic acid, 2-methylbutanedioic acid, 2-ethylpentanedioic acid, 2-n-dodecylbutanedioic acid, 2-n-dodecenylbutanedioic acid, 2-phenylbutanedioic acid, 2-(p-methylphenyl)butanedioic acid, 2,2-dimethylbutanedioic acid, 2,3-dimethylbutanedioic acid; 2,3,4-trimethylpentanedioic acid, 2,2,3-trimethyl 2-ethyl-3-methylbutanedioic acid, maleic acid, fumaric acid, pent-2-enedioic acid, hex-2-enedioic acid; hex-3-enedioic acid; 5-methylhex-2-enedioic acid; 2,3-dimethylpent-2-enedioic acid; 2-methylbut-2-enedioic acid, 2-dodecylbut-2-enedioic acid, phthalic acid, isophthalic acid, terephthalic acid and substituted phthalic acids such as 3-methylbenzene-1,2-dicarboxylic acid; 4-phenylbenzene-1,3-dicarboxylic acid; 2-(1-propenyl)benzene-1,4-dicarboxylic acid, and 3,4-dimethylbenzene-1,2-dicarboxylic acid.

[0049] When tricarboxylic acids are used, examples of tricarboxylic acids include benzenetricarboxylic acid (all isomers) and triazinetriiminocarboxylic acids such as 6,6',6''-(1,3,5-triazine-2,4,6-triyltriimino)trihexanoic acid.

[0050] In a preferred embodiment, the coolant according to the invention does not contain any carboxylic acids with a functionality higher than one.

[0051] Silicophosphonate (G) As an optional component, at least one silicophosphonate (G) can be used in the coolant according to the invention.

[0052] Silicophosphonates have the general structure (V) [ka] [In the formula, R 5 is a divalent organic group, preferably a 1,ω-alkylene group having 1 to 6, preferably 1 to 4 carbon atoms, more preferably methylene, 1,2-ethylene, 1,2-propylene, 1,3-propylene or 1,4-butylene, most preferably 1,2-ethylene or 1,3-propylene, especially 1,2-ethylene; R 6 and R 7 are, independently of one another, C1- to C4-alkyl or hydroxy-C2- to C4-alkyl, preferably hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, 2-hydroxyethyl or 2-hydroxypropyl, more preferably hydrogen, methyl, ethyl or propyl. It is of the type.

[0053] Such silicophosphonates may be present as the free phosphonic acid or in the form of their sodium or potassium salts, preferably the sodium or potassium salts, more preferably the sodium salts.

[0054] Additional Coolant Additives (H) Additionally, typical coolant additives may be added to the coolants of the present invention, provided that they do not increase the electrical conductivity beyond the critical value noted above.

[0055] The cooling agent of the present invention may contain, as additional conventional adjuvants, conventional small amounts of antifoaming agents (generally in an amount of 0.003 to 0.008% by weight) and, for reasons of hygiene and safety in case of swallowing, bitter substances (for example of the denatonium benzoate type) and dyes.

[0056] To the extent that similar effects can be achieved using non-ionic additives, the use of non-ionic additives is preferred over ionic alternatives where possible.

[0057] composition The main requirement of the coolant according to the invention is that it exhibits a conductivity at 25°C of less than 50 μS / cm, preferably less than 45 μS / cm (determined according to ASTM D 1125), so that the coolant is suitable for the cooling systems of vehicles with electric engines.

[0058] To achieve that goal, the amount of ionic species, species that may contain ionic by-products, or combinations of species that can form ions such as acids and bases should be kept to a minimum so that the conductivity does not exceed a critical value.

[0059] Therefore, the amounts of components (C) to (H) in the coolant are selected so that the conductivity does not exceed a critical value.

[0060] To keep the combination of ion-forming species to a minimum, the molar ratio of tertiary amine (E) to monocarboxylic acid (F) is 1:0.1 to 1:0.6, preferably 0.15 to 0.5, more preferably 0.2 to 0.4.

[0061] When molecules with a functionality higher than one are used, the number of amino and carboxylic acid groups in compounds (E) and (F), respectively, is taken into consideration.

[0062] Typically, a coolant according to the present invention is composed as follows: (A) at least one glycol: 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight; (B) Water: 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight; (C) at least one azole derivative: 0.01 to 1% by weight, preferably 0.02 to 0.9% by weight, more preferably 0.03 to 0.8% by weight, even more preferably 0.04 to 0.5%, in particular 0.05 to 0.3% by weight; (D) at least one ester of orthosilicic acid or alkoxyalkylsilane: 0.01 to 1% by weight, preferably 0.02 to 0.9% by weight, more preferably 0.03 to 0.8% by weight, even more preferably 0.04 to 0.5% by weight, in particular 0.05 to 0.3% by weight; (E) at least one tertiary amine containing at least one 2-hydroxyethyl or 2-hydroxypropyl group: 0.01 to 1% by weight, preferably 0.015 to 0.9% by weight, more preferably 0.02 to 0.8% by weight; (F) at least one monocarboxylic acid: 0.01 to 1% by weight, preferably 0.015 to 0.8% by weight, more preferably 0.02 to 0.6% by weight; (G) at least one silicophosphonate that may be included if desired: 0 to 1% by weight, preferably 0.01 to 0.8% by weight, more preferably 0.02 to 0.6% by weight; (H) At least one additional coolant additive that may be included if desired: 0 to 0.5 wt. %, preferably 0.01 to 0.4 wt. %, more preferably 0.02 to 0.3 wt. % for each additional coolant additive. However, the total of all ingredients always equals 100% by weight.

[0063] Another embodiment of the present invention is a coolant concentrate. The coolant is typically obtained from the coolant concentrate by diluting it with water (B). Thus, the coolant concentrate typically contains little or no water (B).

[0064] Typically, a coolant concentrate according to the present invention is composed as follows: (A) at least one glycol: 50 to 99.9% by weight, preferably 60 to 99.8% by weight, more preferably 75 to 99.7% by weight; (B) Water: 0 to 10% by weight, preferably 0 to 8% by weight, more preferably 0 to 5% by weight; (C) at least one azole derivative: 0.02 to 1% by weight, preferably 0.04 to 0.8% by weight, more preferably 0.06 to 0.6% by weight, even more preferably 0.08 to 0.5% by weight, in particular 0.1 to 0.4% by weight; (D) at least one ester of orthosilicic acid or alkoxyalkylsilane: 0.02 to 1% by weight, preferably 0.04 to 0.8% by weight, more preferably 0.06 to 0.6% by weight, even more preferably 0.08 to 0.5% by weight, in particular 0.1 to 0.4% by weight; (E) at least one tertiary amine containing at least one 2-hydroxyethyl or 2-hydroxypropyl group: 0.02 to 0.8% by weight, preferably 0.03 to 0.6% by weight, more preferably 0.04 to 0.5% by weight; (F) at least one monocarboxylic acid: 0.01 to 0.5% by weight, preferably 0.02 to 0.3% by weight, more preferably 0.03 to 0.2% by weight; (G) at least one silicophosphonate that may be included if desired: 0 to 1% by weight, preferably 0.02 to 0.8% by weight, more preferably 0.04 to 0.6% by weight; (H) At least one additional coolant additive that may be included if desired: 0 to 0.5 wt. %, preferably 0.002 to 0.4 wt. %, more preferably 0.004 to 0.3 wt. % for each additional coolant additive. However, the total of all ingredients always equals 100% by weight.

[0065] Another embodiment of the present invention is a refrigerant super concentrate. The refrigerant concentrate is typically obtained by diluting the refrigerant super concentrate with glycol (A), and the refrigerant can be obtained by diluting the refrigerant super concentrate with glycol (A) and water (B), respectively. Thus, the refrigerant concentrate typically contains little or no water (B) and little or no glycol (A).

[0066] Typically, a refrigerant super concentrate according to the present invention is composed as follows: (A) at least one glycol: 70 to 99.5% by weight, preferably 80 to 99% by weight, more preferably 90 to 98% by weight; (B) Water: 0 to 10% by weight, preferably 0 to 8% by weight, more preferably 0 to 5% by weight; (C) at least one azole derivative: 0.05 to 5% by weight, preferably 0.1 to 4% by weight, more preferably 0.2 to 3% by weight, even more preferably 0.3 to 2%, in particular 0.4 to 1.5% by weight; (D) at least one ester of orthosilicic acid or alkoxyalkylsilane: 0.05 to 5% by weight, preferably 0.1 to 4% by weight, more preferably 0.2 to 3% by weight, even more preferably 0.3 to 2% by weight, in particular 0.4 to 1.5% by weight; (E) at least one tertiary amine containing at least one 2-hydroxyethyl or 2-hydroxypropyl group: 0.1 to 4% by weight, preferably 0.15 to 3% by weight, more preferably 0.2 to 2.5% by weight; (F) at least one monocarboxylic acid: 0.05 to 1% by weight, preferably 0.1 to 0.9% by weight, more preferably 0.2 to 0.8% by weight; (G) at least one silicophosphonate that may be included if desired: 0 to 5% by weight, preferably 0.02 to 4% by weight, more preferably 0.04 to 3% by weight; (H) At least one additional coolant additive that may optionally be included: 0 to 1 wt. %, preferably 0.005 to 0.8 wt. %, more preferably 0.008 to 0.6 wt. % for each additional coolant additive. However, the total of all ingredients always equals 100% by weight.

[0067] Due to its low electrical conductivity, the coolant according to the invention can be used in the cooling systems of vehicles equipped with electric engines, fuel cells or hybrid engines that combine combustion and electric engines or combustion and fuel cell engines.

[0068] Example The following examples illustrate the present invention without, however, limiting it in any way.

[0069] Coolant compositions were prepared by mixing the ingredients listed in Table 1 (all amounts are in weight percent). The properties and physical parameters noted in Table 1 were determined as follows: Appearance Visual Water, % DIN 51777 Density at 20°C, g / cm3 DIN 51757 pH (as is) ASTM D 1287 Reserve alkalinity per 10 mL, mL 0.1 mol / L HCl ASTM D 1121 Refractive index at 20°C DIN 51423 Conductivity at 25°C, μS / cm ASTM D 1125

[0070] Examples 2, 4, 5 and 6 are for comparative purposes, while Examples 1, 3, 7 and 8 are according to the invention.

[0071] To ensure sufficient reserve alkalinity necessary to buffer the acidic decomposition products of the coolant, various bases were used to bring the coolant to a slightly alkaline pH value.

[0072] It can be easily seen that when the strong bases potassium hydroxide and sodium hydroxide (Comparative Examples 4 and 5) are used to achieve the target pH value, the conductivity rises to unacceptably high values ​​due to their complete dissociation.

[0073] When diisopropylamine is used as the base (Comparative Example 2), the conductivity decreases, but it still remains above the critical value of 50 μS / cm, which is achieved only with the base (E) according to the invention (octyldiethanolamine in Example 3 and, preferably, triethanolamine in Example 1).

[0074] Varying the carboxylic acid shows that the conductivity remains above the critical value of 50 μS / cm when using the dicarboxylic acid sebacic acid (Comparative Example 6). The aromatic monocarboxylic acid benzoic acid (Example 8) shows good values, while the aliphatic monocarboxylic acids ethylhexanoic acid (Example 7) and especially isononanoic acid (Example 1) are the most preferred.

[0075] [Table 1]

[0076] Corrosion example The coolant composition of Example 1 and 0.01 wt. % of a silicophosphonate [formula (V), R 5 = 1,3-propylene, R 6 , R 7 = methyl and ethyl (statistical mixture), sodium salt] were compared in a corrosion test at 88°C according to ASTM D 1384. The values ​​of pH, reserve alkalinity, conductivity and silicon content were measured before and after the corrosion test.

[0077] [Table 2]

[0078] The corrosion test and pH value results are comparable within the accuracy of the measurements, but the decrease in reserve alkalinity and loss of silicon content is less pronounced in the presence of silicophosphonate than in its absence.

[0079] Therefore, the coolant preferably contains at least one silicophosphonate which reduces the consumption of tetraethoxysilane, which acts as an inhibitor of aluminum corrosion. Other embodiments Some embodiments are given below. Item 1 (A) at least one glycol; (B) Water; (C) at least one azole derivative; (D) at least one ester of orthosilicic acid or an alkoxyalkylsilane; (E) at least one tertiary amine containing at least one 2-hydroxyethyl or 2-hydroxypropyl group; (F) at least one monocarboxylic acid; (G) at least one optional silicophosphonate; (H) At least one optional additional coolant additive. A coolant comprising: the molar ratio of the tertiary amine (E) to the monocarboxylic acid (F) is 1:0.1 to 1:0.6; The coolant wherein components (C)-(H) are present in amounts such that the coolant exhibits a conductivity of less than 50 μS / cm, preferably less than 45 μS / cm. Section 2 Item 1. The coolant according to item 1, wherein the glycol (A) is selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propanediol, higher polyalkylene glycols, alkylene glycol ethers, and glycerol. Section 3 10. The coolant of any one of the preceding claims, wherein the azole derivative (C) is selected from the group consisting of benzimidazole, benzotriazole, tolutriazole, hydrogenated tolutriazole, (2-benzothiazylthio)acetic acid and (2-benzothiazylthio)propionic acid. Section 4 10. The coolant of any one of the preceding claims, wherein the ester of orthosilicic acid (D) is orthosilicic acid tetraethyl ester or orthosilicic acid tetramethyl ester. Section 5 The tertiary amine (E) is ·General formula (I)

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Claims

1. (A) at least one glycol; (B) water; (C) at least one azole derivative; (D) at least one ester of orthosilicic acid or an alkoxyalkylsilane; (E) at least one tertiary amine containing at least one 2-hydroxyethyl or 2-hydroxypropyl group; (F) at least one monocarboxylic acid; (G) at least one optional silicophosphonate; (H) At least one optional additional coolant additive. A coolant comprising: the molar ratio of the tertiary amine (E) to the monocarboxylic acid (F) is 1:0.1 to 1:0.6; The coolant wherein components (C) through (H) are present in amounts such that the coolant exhibits a conductivity of less than 50 μS / cm.

2. 2. The coolant of claim 1, wherein the glycol (A) is selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propanediol, higher polyalkylene glycols, alkylene glycol ethers, and glycerol.

3. 3. The coolant according to claim 1, wherein the azole derivative (C) is selected from the group consisting of benzimidazole, benzotriazole, tolutriazole, hydrogenated tolutriazole, (2-benzothiazylthio)acetic acid and (2-benzothiazylthio)propionic acid.

4. 4. The coolant according to claim 1, wherein the ester of orthosilicic acid (D) is orthosilicic acid tetraethyl ester or orthosilicic acid tetramethyl ester.

5. Tertiary amine (E) ・General formula (I) 【Chemistry 1】 [In the formula, R 2 and R 3 are, independently of each other, straight-chain or branched alkyl substituents containing 1 to 18 carbon atoms, or may be joined together to form a 5- or 6-membered ring containing a nitrogen atom; X i Ha-CH 2 -CH 2 -O-, -CH 2 -CH(CH 3 )-O- or -CH(CH 3 )-CH 2 -O-; n is a positive integer from 1 to 5. The compound ・General formula (II) 【Chemistry 2】 [In the formula, R 4 is a straight or branched alkyl substituent containing 1 to 18 carbon atoms; Each X for i=1 to p and 1 to q i are independently -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3 )-O- or -CH(CH 3 )-CH 2 -O-; and p and q are each independently a positive integer from 1 to 5. The compound Tertiary amines containing three 2-hydroxyethyl or 2-hydroxypropyl groups The coolant according to any one of claims 1 to 4, selected from:

6. 6. The coolant of claim 5, wherein the tertiary amine of general formula (I) is selected from the group consisting of dimethylethanolamine, dimethylpropanolamine, diethylethanolamine, diethylpropanolamine, di-n-butylethanolamine, di-n-butylpropanolamine, N-hydroxyethylpyrrolidine, N-hydroxyethylpiperidine, and N-hydroxyethylmorpholine.

7. The coolant of claim 5, wherein R 4 is an alkyl substituent containing from 4 to 14 carbon atoms.

8. 6. The coolant of claim 5, wherein the tertiary amine of general formula (II) is bis(2-hydroxyethyl)amine or bis(2-hydroxypropyl)amine derived from an amine containing the partial structure R 4 -N 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 a mixture thereof.

9. 6. The cooling agent of claim 5, wherein the tertiary amine containing three 2-hydroxyethyl or 2-hydroxypropyl groups is selected from the group consisting of triethanolamine and tripropanolamine.

10. 10. Coolant according to any one of claims 1 to 9, wherein the monocarboxylic acid (F) is aliphatic, aromatic or cycloaliphatic.

11. 11. Coolant according to any one of claims 1 to 10, wherein the monocarboxylic acid (F) is linear or branched aliphatic.

12. 12. The coolant according to any one of claims 1 to 11, wherein the monocarboxylic acid (F) is selected from the group consisting of 2-ethylhexanoic acid and isononanoic acid.

13. 13. The coolant of any one of claims 1 to 12, wherein no carboxylic acids with a functionality higher than 1 are present.

14. 14. The coolant concentrate of any one of claims 1 to 13, having a water content of 5% by weight or less.

15. Use of a coolant according to any one of claims 1 to 13 as a coolant in the cooling system of a vehicle equipped with an electric engine, a fuel cell, or a hybrid engine combining a combustion engine with an electric engine or a combustion engine with a fuel cell.

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