Novel coolant with low conductivity

Abstract

The present application describes a coolant having a low electrical conductivity, a corresponding coolant concentrate, and the use of such a coolant in a cooling system of a vehicle with an electric motor, a fuel cell or a hybrid engine having a combination of an internal combustion engine and an electric motor or an internal combustion engine and a fuel cell.

Description

[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 having an electric motor, a fuel cell, or a hybrid engine having a combination of an internal combustion engine and an electric motor or a combination of an internal combustion engine and a fuel cell.

[0002] WO 02 / 101848 discloses a coolant comprising azole derivatives and orthosilicates for cooling fuel cell drives. This disclosed coolant contains no acids or amines, as these would increase their electrical conductivity. However, low electrical conductivity is crucial for this coolant to prevent electrode short circuits and improve the safety characteristics of the cooling system.

[0003] The disadvantage is that, in order to maintain low conductivity, this coolant does not contain any alkaline components necessary to neutralize the acidic degradation products, which in turn cause corrosion.

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

[0005] Alkoxylated amines are used as corrosion inhibitors against corrosion of iron- or copper-containing alloys. Coolants disclosed in this way do not contain any carboxylic acids, as 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 these organic carboxylic acids typically lack good corrosion resistance to these metals due to their additionally increased conductivity.

[0006] Therefore, one object of the present invention is to provide coolants that exhibit sufficiently low electrical conductivity, making them suitable for use in vehicles with electric drives.

[0007] The objective is achieved by a coolant comprising the following components:

[0008] (A) at least one diol

[0009] (B) Water

[0010] (C) at least one azole derivative

[0011] (D) At least one orthosilicate or alkoxyalkylsilane

[0012] (E) at least one tertiary amine containing at least one 2-hydroxyethyl or 2-hydroxypropyl group.

[0013] (F) at least one monocarboxylic acid

[0014] (G) Optionally at least one phosphonate

[0015] (H) Optionally at least one other coolant additive

[0016] in

[0017] The molar ratio between tertiary amines (E) and monocarboxylic acids (F) is 1:0.1 to 1:0.6.

[0018] - Components (C) to (H) are present in an amount such that the coolant exhibits a conductivity of less than 100, preferably less than 50, more preferably less than 45 μS / cm.

[0019] These coolants exhibit low electrical conductivity (making them suitable for use in vehicles with electric drives) and good corrosion resistance. The presence of at least one monocarboxylic acid (F) typically increases the conductivity of the coolant; however, its advantages in corrosion inhibition make the increase in conductivity acceptable.

[0020] The detailed information of the ingredients is as follows:

[0021] Diol (A)

[0022] As an alkylene glycol component or a derivative thereof (A), particularly monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and mixtures thereof, as well as propylene 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 monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether and tetraethylene glycol monobutyl ether, or glycerol, may be used alone or as mixtures thereof in various cases.

[0023] Water (B)

[0024] The water used in the coolant of this invention should be ion-free, meaning water with a neutral pH and substantially free of ions other than hydroxide ions and hydrated hydrogen ions released by the proton self-migration reaction of water at the corresponding temperature.

[0025] The conductivity of the deionized water used at 25°C (as determined herein according to ASTM D 1125) should preferably not exceed 5 μS / cm, more preferably not exceed 3, even more preferably not exceed 2, and particularly not exceed 1 μS / cm.

[0026] The deion-free water used can be pure distilled water, double-distilled water, or water that has had its ions removed, for example, through ion exchange.

[0027] Azole derivatives (C)

[0028] In the context of this invention, azole derivatives refer to five-membered heterocyclic compounds having two or three heteroatoms selected from nitrogen and sulfur and containing no or at most one sulfur atom and may have an aromatic or saturated six-membered fused ring.

[0029] These five-membered heterocyclic compounds (azole derivatives) typically 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.

[0030] The preferred group of specified azole derivatives are cyclized imidazoles and cyclized 1,2,3-triazoles of the following general formula.

[0031]

[0032] or

[0033] in

[0034] Variable R is hydrogen or C1-C 10 -alkyl, especially methyl or ethyl, and

[0035] Variable X is a nitrogen atom or a CH group.

[0036] Typical and preferred examples of azole derivatives of general formula (I) are benzimidazole (X=CH, R=H), benzotriazole (X=N, R=H), and tolutriazole (tolyltriazole) (X=N, R=CH3). Typical examples of azole derivatives of general formula (II) are hydrogenated 1,2,3-tolutriazole (tolyltriazole) (X=N, R=CH3).

[0037] Another preferred group of the specified azole derivatives is benzothiazole of general formula (III).

[0038]

[0039] in

[0040] The variable R is defined as above and

[0041] Variable R' is hydrogen, C1-C 10 -alkyl, especially methyl or ethyl, or especially mercapto (-SH). A typical example of an azole derivative of general formula (III) is 2-mercaptobenzothiazole.

[0042] (2-Benzothiazolylthio)acetic acid (R'=-S-CH2-COOH) or (2-benzothiazolylthio)propionic acid (R'=-S-CH2-CH2-COOH) can also be used, but are less preferred. This embodiment is less preferred because the use of such free acid compounds increases the conductivity of the coolant.

[0043] Other suitable azole derivatives are noncyclized azole derivatives of general formula (IV).

[0044] in

[0045] Variables X and Y together represent two nitrogen atoms or

[0046] One nitrogen atom and one CH group,

[0047] For example, 1H-1,2,4-triazole (X=Y=N) or preferably imidazole (X=N, Y=CH).

[0048] For the purposes of this invention, benzimidazole, benzotriazole, toluenetriazole, hydrogenated toluenetriazole or mixtures thereof, especially benzotriazole or toluenetriazole, are very particularly preferred as azole derivatives.

[0049] The azole derivatives mentioned are commercially available or can be prepared by conventional methods. Hydrogenated benzotriazoles, such as hydrogenated toluenetriazole, are also available as described in DE-A 1 948 794 and are commercially available.

[0050] Orthosilicates or alkoxyalkylsilanes (D)

[0051] Orthosilicate is of the formula Si(OR) 1 Compounds of 4,

[0052] in

[0053] R 1 The organic substituent is an organic substituent containing 1 to 6 carbon atoms, such as a straight chain or a branched chain, preferably a straight-chain alkyl substituent containing 1 to 6 carbon atoms or an aryl 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.

[0054] Alkoxyalkylsilanes are less preferred, and the alkoxy substituents and alkyl groups both contain straight or branched chains, preferably containing straight-chain alkyl substituents with 1 to 6 carbon atoms, more preferably containing alkyl substituents with 1 to 4 carbon atoms, and even more preferably containing alkyl substituents with 1 or 2 carbon atoms.

[0055] Typical examples of compound (D) are tetraalkoxysilanes, preferably tetramethoxysilanes and tetraethoxysilanes, and alkoxyalkylsilanes, preferably triethoxymethylsilanes, diethoxydimethylsilanes, ethoxytrimethylsilanes, trimethoxymethylsilanes, dimethoxydimethylsilanes, and methoxytrimethylsilanes. Tetraalkoxysilanes are preferred, particularly tetramethoxysilanes and tetraethoxysilanes, and very particularly preferred tetraethoxysilanes.

[0056] Compound (D) is primarily used as an inhibitor of aluminum corrosion.

[0057] Tertiary amines (E)

[0058] At least one tertiary amine (E) contains at least one 2-hydroxyethyl or 2-hydroxypropyl group. Potential tertiary amines (E) may contain one, two, or three 2-hydroxyethyl or 2-hydroxypropyl groups, preferably two or three 2-hydroxyethyl or 2-hydroxypropyl groups, and more preferably 2-hydroxyethyl.

[0059] The tertiary amine (E) may be aliphatic, alicyclic or aromatic group 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.

[0060] These substituents are preferably aliphatic or aromatic, more preferably aliphatic.

[0061] The aromatic substituents can be, for example, phenyl, tolyl, or naphthyl.

[0062] Aliphatic substituents can be straight-chain or branched, preferably straight-chain alkyl substituents containing 1 to 18 carbon atoms, more preferably 2 to 16, more preferably 4 to 14, and especially 6 to 12 carbon atoms.

[0063] In compound (E), the substituents are preferably derived from fatty amines, which are preferably obtained by hydrogenation and amination of fatty acids and esters, particularly preferably by hydrogenation and amination of the following substances: 2-ethylhexanoic acid, octanoic acid, nonanoic acid, 2-propenheptanic acid, decanoic acid, undecanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid (myristic acid), pentadecanoic acid, palmitic acid (hexadecanoic acid), palmitoleic acid [(9Z)-hexadecano-9-enoic acid], heptadecanoic acid (heptadecanoic acid) Stearic acid (octadecanoic acid), oleic acid [(9Z)-octadec-9-enoic acid], transoleic acid [(9E)-octadec-9-enoic acid], linoleic acid [(9Z,12Z)-octadec-9,12-dienoic acid], linolenic acid [(9Z,12Z,15Z)-octadec-9,12,15-trienoic acid], tung oil acid [(9Z,11E,13E)-octadec-9,11,13-trienoic acid], ricinoleic acid ((R)-12-hydroxy-(Z)-octadec-9-enoic acid), isorhinol [(S)-9-hydroxy-(Z)-octadec-12-enoic acid], nonadecanoic acid, arachidic acid (eicosanoic acid), benzanoic acid (docosahexaenoic acid) and erucic acid [(13Z)-docosahexaenoic acid].

[0064] Examples of tertiary amines (E) with one 2-hydroxyethyl or 2-hydroxypropyl group and two other substituents are those of general formula (I).

[0065]

[0066] in

[0067] R 2 and R 3 The substituents, which are independent of each other as described above, are preferably straight-chain or branched, preferably straight-chain alkyl substituents containing 1 to 18 carbon atoms, more preferably 2 to 16, more preferably 4 to 14, and especially 6 to 12 carbon atoms, or together can form a five- or six-membered ring including a nitrogen atom.

[0068] X i It is -CH2-CH2-O-, -CH2-CH(CH3)-O-, or -CH(CH3)-CH2-O-, preferably -CH2-CH2-O-, and

[0069] n is 1 to 5, preferably 1 to 4, more preferably 1 to 3, even more preferably 1 or 2, especially a positive integer of 1.

[0070] Preferred individuals are dimethylethanolamine, dimethylpropanolamine, diethylethanolamine, diethylpropanolamine, di-n-butylethanolamine, di-n-butylpropanolamine, N-hydroxyethylpyrrolidine, N-hydroxyethylpiperidine, and N-hydroxyethylmorpholine.

[0071] Examples of tertiary amines (E) having two 2-hydroxyethyl or 2-hydroxypropyl groups and one other substituent have the general formula (II).

[0072]

[0073] in

[0074] R 4 The substituents described above are preferably straight-chain or branched, and preferably straight-chain alkyl substituents containing 1 to 18 carbon atoms, more preferably 2 to 16, more preferably 4 to 14, and especially 6 to 12 carbon atoms.

[0075] Each Xi (i = 1 to p and 1 to q) is independently selected from -CH2-CH2-O-, -CH2-CH(CH3)-O-, or -CH(CH3)-CH2-O-, preferably -CH2-CH2-O-, and

[0076] p and q are independent of each other and are positive integers ranging from 1 to 5, preferably from 1 to 4, more preferably from 1 to 3, even more preferably from 1 or 2, and especially from 1.

[0077] The preferred individual is one with the following substituent R 4 Bis(2-hydroxyethyl)amine or bis(2-hydroxypropyl)amine: 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.

[0078] Bis(2-hydroxyethyl)-substituted n-hexylamine, n-octylamine, 2-ethylhexylamine and n-decylamine are particularly preferred, of which n-octylamine and 2-ethylhexylamine, especially bis(2-hydroxyethyl)n-octylamine, are particularly preferred.

[0079] These compounds are preferably produced by reacting the corresponding amine R under alkaline conditions. 4 -NH2 is obtained by reacting epoxides with alkyl oxidases to the desired average statistical degree of alkoxylation. When structural unit X... i It is particularly preferred when it is derived from ethylene oxide or propylene oxide, preferably from ethylene oxide.

[0080] Examples of tertiary amines (E) containing three 2-hydroxyethyl or 2-hydroxypropyl groups are triethanolamine and tripropanolamine, with triethanolamine being preferred.

[0081] 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.

[0082] Monocarboxylic acids (F)

[0083] Suitable monocarboxylic acids (F) can be straight-chain 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, and especially 8 to 10 carbon atoms.

[0084] Branched aliphatic monocarboxylic acids are superior to their corresponding straight-chain monocarboxylic acids.

[0085] Useful linear or branched, aliphatic or alicyclic monocarboxylic acids (F) include, for example, propionic acid, valeric acid, 2,2-dimethylpropionic acid, hexanoic acid, 2,2-dimethylbutyric acid, cyclohexylacetic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, decanoic acid, undecanoic acid, or dodecanoic acid.

[0086] Suitable aromatic monocarboxylic acids (F) are particularly benzoic acid; also useful are, for example, C1- to C8-alkylbenzoic acids such as o-methylbenzoic acid, m-methylbenzoic acid, p-methylbenzoic acid or p-tert-butylbenzoic acid, and hydroxyl-containing aromatic monocarboxylic acids such as o-hydroxybenzoic acid, m-hydroxybenzoic acid or p-hydroxybenzoic acid, o-(hydroxymethyl)benzoic acid, m-(hydroxymethyl)benzoic acid or p-(hydroxymethyl)benzoic acid or halobenzoic acids such as o-fluorobenzoic acid, m-fluorobenzoic acid or p-fluorobenzoic acid.

[0087] 2-Ethylhexanoic acid and isononanoic acid are particularly preferred.

[0088] 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 may 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-tetramethylvaleric acid (e.g., CAS No. 3302-12-3), and combinations thereof. In a preferred embodiment, isononanoic acid has more 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-tetramethylvaleric acid as its main component. The balance of isononanoic acid may include other nine-carbon carboxylic acid isomers and small amounts of one or more contaminants. In a preferred embodiment, isononanoic acid has more than 90% 3,5,5-trimethylhexanoic acid as its major component, and even more preferably, the major component is more than 95% 3,5,5-trimethylhexanoic acid.

[0089] However, a disadvantage is that, in addition to or instead of monocarboxylic acids, carboxylic acids with higher functionality, such as dicarboxylic acids or tricarboxylic acids, can be used. Compared to commonly used dicarboxylic acids, the use of monocarboxylic acids has been shown to exhibit superior results; see the examples.

[0090] If used, the dicarboxylic acid or tricarboxylic acid can 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, and especially up to 12 carbon atoms.

[0091] Examples of dicarboxylic acids, if used, include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, alkyl or alkenyl succinic acid, 2-methylsuccinic acid, 2-ethylglutaric acid, 2-dodecylsuccinic acid, 2-dodecenylsuccinic acid, 2-phenylsuccinic acid, 2-(p-methylphenyl)succinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid; 2,3,4-trimethylglutaric acid, 2,2,3-trimethylglutaric acid; 2-ethyl-3 -Methylsuccinic acid, maleic acid, fumaric acid, pent-2-enic acid, hex-2-enic acid; hex-3-enic acid; 5-methylhex-2-enic acid; 2,3-dimethylpent-2-enic acid; 2-methylbut-2-enic acid, 2-dodecylbut-2-enic acid, phthalic acid, isophthalic acid, terephthalic acid and substituted phthalic acids such as 3-methylphenyl-1,2-dicarboxylic acid; 4-phenylphenyl-1,3-dicarboxylic acid; 2-(1-propenyl)phenyl-1,4-dicarboxylic acid and 3,4-dimethylphenyl-1,2-dicarboxylic acid.

[0092] If used, examples of tricarboxylic acids are benzotricarboxylic acid (all isomers) and triazine triiminocarboxylic acids, such as 6,6',6"-(1,3,5-triazine-2,4,6-trimethyltriimino)trihexanoic acid.

[0093] In a preferred embodiment, the coolant according to the invention does not contain any carboxylic acid with a functionality greater than 1.

[0094] Silicates (G)

[0095] As an optional component, at least one phosphonate (G) may be used in the coolant of the present invention.

[0096] Silicates are those that have the general formula (V).

[0097]

[0098] in

[0099] R 5 It is a divalent organic residue, preferably a 1,ω-alkylene group having 1 to 6, more 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.

[0100] R 6 and R 7 Each of the compounds is independently a C1- to C4-alkyl group, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, preferably methyl or ethyl.

[0101] This phosphosilicate can exist in the form of free phosphonic acid or its sodium or potassium salt, preferably sodium or potassium salt, more preferably sodium salt.

[0102] Other coolant additives (H)

[0103] Other typical coolant additives may also be added to the coolant of the present invention, as long as they do not increase the conductivity above the critical value indicated above.

[0104] As other commonly used additives, the coolant of the present invention may also contain a small amount of defoamer (usually 0.003 to 0.008% by weight), and for hygiene and safety reasons, may also contain bitter substances (e.g., denatium benzoate) and dyes if swallowed.

[0105] If a similar effect can be achieved using a nonionic additive, then using a nonionic additive is preferable to using an ionic substitute, whenever possible.

[0106] Composition

[0107] The main requirement for the coolant of the present invention is that the coolant exhibits an electrical conductivity of less than 50, preferably less than 45 μS / cm (as determined according to ASTM D 1125) at 25°C, so that it is suitable for cooling systems of vehicles with electric motors.

[0108] To achieve this goal, the amount of ionic substances, substances that may contain ionic byproducts, or combinations of substances that can form ions (such as acids and bases) should be kept to a minimum to avoid raising the conductivity above the critical value.

[0109] Therefore, the amounts of components (C) to (H) in the coolant are selected in a manner that does not exceed the critical value of conductivity.

[0110] In order to keep the combination of substances that form ions to a minimum, the molar ratio between the tertiary amine (E) and the monocarboxylic acid (F) is 1:0.1 to 1:0.6, preferably 0.15 to 0.5 and more preferably 0.2 to 0.4.

[0111] When using molecules with a functionality greater than 1, refer to the number of amino groups relative to carboxylic acid groups in compound (F) relative to compound (E).

[0112] Typically, the coolant composition of this invention is as follows:

[0113] (A) At least one diol: 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight

[0114] (B) Water: 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight

[0115] (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%, particularly 0.05 to 0.3% by weight.

[0116] (D) At least one orthosilicate 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%, particularly 0.05 to 0.3% by weight.

[0117] (E) At least one tertiary amine having 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.

[0118] (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.

[0119] (G) Optionally, at least one phosphonate: 0 to 1% by weight, preferably 0.01 to 0.8% by weight, more preferably 0.02 to 0.6% by weight.

[0120] (H) Optionally, at least one other coolant additive: for each other coolant additive, 0 to 0.5% by weight, preferably 0.01 to 0.4% by weight, more preferably 0.02 to 0.3% by weight.

[0121] The condition is that the total of all components always adds up to 100% by weight.

[0122] Another embodiment of the invention is a coolant concentrate. Coolant is typically obtained by diluting a coolant concentrate with water (B). Therefore, the coolant concentrate typically contains a small amount of water (B) or no water (B).

[0123] Typically, the coolant concentrate of the present invention has the following composition:

[0124] (A) At least one diol: 50 to 99.9% by weight, preferably 60 to 99.8% by weight, more preferably 75 to 99.7% by weight.

[0125] (B) Water: 0 to 10% by weight, preferably 0 to 8% by weight, more preferably 0 to 5% by weight

[0126] (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%, particularly 0.1 to 0.4% by weight.

[0127] (D) At least one orthosilicate 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%, particularly 0.1 to 0.4% by weight.

[0128] (E) At least one tertiary amine having 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.

[0129] (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.

[0130] (G) Optionally, at least one phosphonate: 0 to 1% by weight, preferably 0.02 to 0.8% by weight, more preferably 0.04 to 0.6% by weight.

[0131] (H) Optionally, at least one other coolant additive: for each other coolant additive, 0 to 0.5% by weight, preferably 0.002 to 0.4% by weight, more preferably 0.004 to 0.3% by weight.

[0132] The condition is that the total of all components always adds up to 100% by weight.

[0133] Other embodiments of the invention are coolant superconcentrates. Coolant concentrates are typically obtained by diluting coolant superconcentrates with diol (A), and correspondingly, coolant can be obtained by diluting coolant superconcentrates with diol (A) and water (B). Therefore, coolant concentrates typically contain a small amount of water (B) or no water (B) and a small amount of diol (A) or no diol (A).

[0134] Typically, the coolant superconcentrate of the present invention has the following composition:

[0135] (A) At least one diol: 70 to 99.5% by weight, preferably 80 to 99% by weight, more preferably 90 to 98% by weight

[0136] (B) Water: 0 to 10% by weight, preferably 0 to 8% by weight, more preferably 0 to 5% by weight

[0137] (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%, particularly 0.4 to 1.5% by weight.

[0138] (D) At least one orthosilicate 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%, particularly 0.4 to 1.5% by weight.

[0139] (E) At least one tertiary amine having 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.

[0140] (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.

[0141] (G) Optionally, at least one phosphonate: 0 to 5% by weight, preferably 0.02 to 4% by weight, more preferably 0.04 to 3% by weight.

[0142] (H) Optionally, at least one other coolant additive: for each other coolant additive, 0 to 1% by weight, preferably 0.005 to 0.8% by weight, more preferably 0.008 to 0.6% by weight.

[0143] The condition is that the total of all components always adds up to 100% by weight.

[0144] Due to the low electrical conductivity of the coolants of the present invention, they can be used in vehicle cooling systems having electric motors, fuel cells, or hybrid engines having a combination of internal combustion engines and electric motors or a combination of internal combustion engines and fuel cells. Example

[0145] The present invention is illustrated in the following embodiments, but is not limited thereto.

[0146] The coolant composition was prepared by mixing the components listed in Table 1 (all amounts are given in wt%), and the characteristics and physical parameters indicated in Table 1 were determined as follows:

[0147]

[0148] Examples 2, 4, 5 and 6 are for comparative purposes, while Examples 1, 3, 7 and 8 are based on the present invention.

[0149] Different alkalis are used to make the pH of the coolant slightly alkaline to ensure sufficient reserve alkalinity necessary to buffer the acidic degradation products of the coolant.

[0150] It is easy to see that using strong bases such as potassium hydroxide and sodium hydroxide (Comparative Examples 4 and 5) to achieve the target pH value increases the conductivity to unacceptably high levels because they completely dissociate.

[0151] Using diisopropylamine as a base (Comparative Example 2) reduced the conductivity, but it still remained above the critical value of 50 μS / cm. Only the base (E) of the present invention (octyldiethanolamine in Example 3, and preferably triethanolamine in Example 1) can achieve this critical value.

[0152] The changes in carboxylic acids indicate that the use of dicarboxylic acid sebacic acid (Comparative Example 6) resulted in a conductivity exceeding the critical value of 50 μS / cm. Aromatic monocarboxylic acid benzoic acid (Example 8) produced good values, while aliphatic monocarboxylic acid ethylhexanoic acid (Example 7), and especially isononanoic acid (Example 1), were the most preferred.

[0153]

[0154] Corrosion Examples

[0155] The coolant composition of Example 1 and also containing 0.01% by weight of phosphonate (formula (V), R) 5 =1,3-Propylene, R 6 R 7 The composition of Example 1 (a mixture of methyl and ethyl (statistical mixture), sodium salt) was compared in a corrosion test at 88°C according to ASTM D 1384.

[0156] pH value, reserve alkalinity, conductivity and silicon content were measured before and after the corrosion test.

[0157]

[0158] Although the results of corrosion tests and pH values ​​are comparable in terms of measurement accuracy, the decrease in reserve alkalinity and loss of silicon content in the presence of phosphonates are less pronounced than in the absence of phosphonates.

[0159] Therefore, the preferred coolant contains at least one phosphonate, which reduces the consumption of tetraethoxysilane, which is used as an aluminum corrosion inhibitor.

Claims

1. Coolant, which contains (A) at least one diol (B) Water (C) at least one azole derivative (D) At least one orthosilicate or alkoxyalkylsilane (E) at least one tertiary amine having at least one 2-hydroxyethyl or 2-hydroxypropyl group (F) at least one monocarboxylic acid (G) Optionally at least one phosphonate (H) Optionally at least one other coolant additive in The molar ratio between tertiary amines (E) and monocarboxylic acids (F) is 1:0.1 to 1:0.

6. - Components (C) to (H) are present in an amount such that the coolant exhibits an electrical conductivity of less than 50 μS / cm.

2. The coolant according to claim 1, wherein components (C) to (H) are present in an amount such that the coolant exhibits a conductivity of less than 45 μS / cm.

3. The coolant according to claim 1 or 2, wherein the diol (A) is selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, higher polyalkylene glycols, alkylene glycol ethers, and glycerol.

4. The coolant according to claim 1 or 2, wherein the azole derivative (C) is selected from benzimidazole, benzotriazole, toluenetriazole, hydrogenated toluenetriazole, (2-benzothiazolylthio)acetic acid and (2-benzothiazolylthio)propionic acid.

5. The coolant according to claim 1 or 2, wherein the orthosilicate ester (D) is tetraethyl orthosilicate or tetramethyl orthosilicate.

6. The coolant according to claim 1 or 2, wherein the tertiary amine (E) is selected from... - Compounds of general formula (I) Where R 2 and R 3 Each group can be independently 2-hydroxyethyl, 2-hydroxypropyl, or an aliphatic, alicyclic, or aromatic group having up to 20 carbon atoms, or they can together form a five- or six-membered ring containing a nitrogen atom. X i It is -CH2-CH2-O-, -CH2-CH(CH3)-O-, or -CH(CH3)-CH2-O-, and n is a positive integer from 1 to 5. - Compounds of general formula (II) in R 4 It is a 2-hydroxyethyl, 2-hydroxypropyl, or an aliphatic, alicyclic, or aromatic group having a maximum of 20 carbon atoms. Each Xi (i = 1 to p and 1 to q) is independently selected from -CH2-CH2-O-, -CH2-CH(CH3)-O-, or -CH(CH3)-CH2-O-, and p and q are independent positive integers from 1 to 5, and - Tertiary amine compounds containing three 2-hydroxyethyl or 2-hydroxypropyl groups.

7. The coolant according to claim 6, wherein R 2 R 3 and R 4 Each group is an aliphatic, alicyclic, or aromatic group that has a maximum of 18 carbon atoms.

8. The coolant according to claim 7, wherein R 2 R 3 and R 4 Each group is an aliphatic, alicyclic, or aromatic group that has a maximum of 16 carbon atoms.

9. The coolant according to claim 8, wherein R 2 R 3 and R 4 Each group is an aliphatic, alicyclic, or aromatic group that has a maximum of 14 carbon atoms.

10. The coolant according to claim 9, wherein R 2 R 3 and R 4 Each group is an aliphatic, alicyclic, or aromatic group that has a maximum of 12 carbon atoms.

11. The coolant according to claim 6, wherein R 2 R 3 and R 4 They are classified independently as aliphatic or aromatic.

12. The coolant according to claim 11, wherein R 2 R 3 and R 4 They are each an aliphatic group, independent of each other.

13. The coolant according to claim 6, wherein R 2 R 3 and R 4 They are phenyl, tolyl, or naphthyl, each independent of the other.

14. The coolant according to claim 6, wherein R 2 R 3 and R 4 Alkyl substituents that are either straight-chain or branched, and are independent of each other.

15. The coolant according to claim 14, wherein R 2 R 3 and R 4 Each of the substituents is a straight-chain alkyl group containing 1 to 18 carbon atoms.

16. The coolant according to claim 15, wherein R 2 R 3 and R 4 Each of the substituents is a straight-chain alkyl group containing 2 to 16 carbon atoms.

17. The coolant according to claim 16, wherein R 2 R 3 and R 4 Each of the substituents is a straight-chain alkyl group containing 4 to 14 carbon atoms.

18. The coolant according to claim 17, wherein R 2 R 3 and R 4 Each of the substituents is a straight-chain alkyl group containing 6 to 12 carbon atoms.

19. The coolant according to claim 6, wherein R 2 R 3 and R 4 They are derived independently from fatty amines.

20. The coolant according to claim 19, wherein R 2 R 3 and R 4 They are derived independently from fatty amines, obtained through the hydrogenation and amination of fatty acids and esters.

21. The coolant according to claim 19, wherein R 2 R 3 and R 4 These substances are independently derived from fatty amines and are obtained through hydrogenation and amination of the following: 2-ethylhexanoic acid, octanoic acid, nonanoic acid, 2-propenylic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, palmitic acid, palmitoleic acid [(9Z)-hexadec-9-enoic acid], heptadecanic acid, stearic acid, oleic acid [(9Z)-octadec-9-enoic acid], transoleic acid [(9E)-octadec-9-enoic acid], linoleic acid [(9Z,12Z)-octadec-9,1... 2-Dienoic acid, linolenic acid [(9Z,12Z,15Z)-octadec-9,12,15-trienoic acid], tung oil acid [(9Z,11E,13E)-octadec-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, benzolic acid and erucic acid [(13Z)-docosahexadec-13-enoic acid].

22. The coolant according to claim 6, wherein X i It is -CH2-CH2-O-.

23. The coolant according to claim 6, wherein n is a positive integer from 1 to 4.

24. The coolant according to claim 23, wherein n is a positive integer from 1 to 3.

25. The coolant according to claim 24, wherein n is 1 or 2.

26. The coolant according to claim 25, wherein n is 1.

27. The coolant according to claim 6, wherein each Xi (i = 1 to p and 1 to q) is independently -CH2-CH2-O-.

28. The coolant according to claim 6, wherein p and q are positive integers from 1 to 4, independent of each other.

29. The coolant according to claim 28, wherein p and q are positive integers from 1 to 3, independent of each other.

30. The coolant according to claim 29, wherein p and q are independently 1 or 2.

31. The coolant according to claim 30, wherein p and q are each independently 1.

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

33. The coolant according to claim 6, wherein the tertiary amine of general formula (II) is a substituent R. 4 Bis(2-hydroxyethyl)amine or bis(2-hydroxypropyl)amine: 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.

34. The coolant according to claim 6, wherein the tertiary amine having three 2-hydroxyethyl or 2-hydroxypropyl groups is selected from triethanolamine and tripropanolamine.

35. The coolant according to claim 1 or 2, wherein the monocarboxylic acid (F) is aliphatic, aromatic or alicyclic.

36. The coolant according to claim 35, wherein the monocarboxylic acid (F) is an aliphatic monocarboxylic acid having 5 to 14 carbon atoms.

37. The coolant according to claim 36, wherein the monocarboxylic acid (F) is an aliphatic monocarboxylic acid having 6 to 12 carbon atoms.

38. The coolant according to claim 1 or 2, wherein the monocarboxylic acid (F) is a straight-chain or branched aliphatic monocarboxylic acid.

39. The coolant according to claim 38, wherein the monocarboxylic acid (F) is a branched aliphatic monocarboxylic acid.

40. The coolant according to claim 1 or 2, wherein the monocarboxylic acid (F) is selected from 2-ethylhexanoic acid and isononanoic acid.

41. The coolant according to claim 1 or 2, wherein there are no carboxylic acids with a functionality greater than 1.

42. A coolant concentrate for obtaining the coolant according to any one of the preceding claims, wherein the water content does not exceed 5% by weight.

43. Use of the coolant according to any one of claims 1 to 41 in the cooling system of a vehicle, the vehicle having an electric motor, a fuel cell, or a hybrid engine having a combination of an internal combustion engine and an electric motor or a combination of an internal combustion engine and a fuel cell.

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