Novel coolant compositions

Abstract

The present invention relates to novel coolant compositions based on freezing point-reducing liquids as main components, specific sulfur-containing organic compounds as corrosion inhibitors, and further corrosion inhibitors different from the corrosion inhibitors.

Description

[0001] describe This invention relates to novel coolant compositions based on a liquid that lowers the freezing point as a main component, a specific sulfur-containing organic compound as a corrosion inhibitor, and other corrosion inhibitors that are different from the corrosion inhibitor.

[0002] Coolant compositions used in cooling systems for internal combustion engines in automobiles (which are typically configured as cooling circuits) generally contain alkyl glycols, such as monoethylene glycol or monopropylene glycol, optionally blended with glycerin, as an antifreeze component that lowers the freezing point of the coolant composition. In particular, corrosion inhibitors are included, among other components such as antifoaming agents, dyes, or bittering substances.

[0003] Especially in modern internal combustion engines, the temperatures reached place stringent requirements on the materials used. Corrosion of any type and degree represents a potential risk factor that could shorten engine life and reduce reliability. Furthermore, many different materials, such as cast iron, copper, brass, solder, steel, and aluminum, aluminum alloys, and magnesium alloys, are increasingly used in modern engines. This diversity of metallic materials can also lead to potential corrosion problems, particularly where different metals come into contact. In these areas, various types of corrosion, such as pitting, crevice corrosion, dissolution, or cavitation, can be more likely to occur. The coolant composition must also be compatible with the non-metallic components of the cooling system (such as elastomers and plastics from hose connections or seals) and these non-metallic components must not be altered. Moreover, the type of coolant composition is crucial for heat transfer in modern internal combustion engines.

[0004] For some time, cooling devices or cooling circuits, commonly used in vehicle and automobile construction but also in stationary internal combustion engines, have been made primarily or solely of aluminum or aluminum alloys. Specific welding processes are employed here, such as welding performed under a protective gas atmosphere. In such welding processes, the accompanying use of flux is essential. Potassium fluoroaluminate is commonly used here as a flux, such as KAlF4, K2AlF5, and K3AlF6 (e.g., under the name Nocolok). ® A mixture of substances that are commercially available.

[0005] A portion of the flux mentioned remains on the surface of the cooling unit after the welding operation. These flux residues in the cooling unit more or less rapidly lead to the precipitation of aluminum hydroxide gel, and thus, after the introduction of the water-based coolant composition and engine operation, the formation of sludge in the cooling circuit due to a series of mutually balanced chemical reactions with the components of the water-based coolant composition. This significantly limits the effectiveness of heat removal from the engine, and therefore also limits the heat exchange function of the heating system, the cooling of the air supply, and the cooling function of the gearbox oil. Furthermore, the presence of aluminum hydroxide gel adversely affects the corrosion protection provided by the coolant, as the corrosion protection effect is significantly reduced due to the adsorption of corrosion inhibitors on the aluminum hydroxide gel. Therefore, a coolant composition with high tolerance to fluoroaluminate flux residues in welded aluminum radiators is needed, i.e., a coolant composition that no longer tends, or to a significantly smaller extent, to form aluminum hydroxide gel precipitates and sludge in the cooling circuit, thus enabling more effective corrosion protection.

[0006] EP 2956520 B1 discloses coolant concentrates, particularly containing certain 2-thiothiazole derivatives with carboxyl alkyl groups.

[0007] Even in the presence of potassium fluoroaluminate, this type of sulfur-containing inhibitor provides excellent inhibition of aluminum corrosion.

[0008] However, a drawback is that the coolant according to EP 2956520 B1 exhibits high electrical conductivity.

[0009] Low electrical conductivity is worth the effort to make coolants suitable for cooling systems in vehicles with electric motors, fuel cells, or hybrid motors, because high electrical conductivity could lead to short circuits if the battery is damaged (e.g., in an accident).

[0010] Therefore, the object of the present invention is to provide a coolant composition having a lower electrical conductivity than that of the coolant according to EP 2956520 B1 but retaining the corrosion-inhibiting activity of those coolants, in the presence of fluoroaluminates.

[0011] The coolant according to the invention must meet the general requirements according to ASTM D3306, and in particular the corrosion tests according to ASTM D4340 and ASTM D1384.

[0012] This objective is achieved by a coolant comprising: (A) At least one antifreeze agent selected from 1,2-ethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerol, their dimers, trimers or oligomers, and their monoalkyl or dialkyl ethers. (B) Water (C1) At least one 2-thiothiazole of general formula (I) Where variable R1 is represented by equation -(C) m H 2m The )-COOX group is a carboxyl alkyl group, wherein m is 1 to 4 and X is hydrogen, an alkali metal cation, an ammonium cation, or a substituted ammonium cation, and variables R2 and R3 are each independently hydrogen or C1-C4-alkyl groups, wherein R2 and R3, together with the two ring carbon atoms of the thiazole ring to which they are attached, can also form a five- or six-membered saturated or unsaturated ring. (C2) optionally at least one azole derivative different from (C1), (D) At least one inorganic salt selected from the group consisting of molybdates, borates, vanadates, tungstates, and antimonates as an additional corrosion inhibitor. (E) At least one inorganic phosphate, optionally used as another corrosion inhibitor. (F) At least one aliphatic, cyclic aliphatic, or aromatic monocarboxylic acid, dicarboxylic acid, or tricarboxylic acid, in the form of an alkali metal salt, ammonium salt, or substituted ammonium salt, having 3 to 21 carbon atoms in the acid moiety, and (G) At least one alkylamine of general formula (II) in R 4 It is an organic group having 6 to 10 carbon atoms, particularly 6 to 10 carbon atoms, preferably 7 to 9 carbon atoms, and especially preferably 8 carbon atoms, of alkyl or alkenyl groups. p and q are each independent of each other and are 1 to 20, preferably 1 to 15, particularly preferably 1 to 10, very particularly preferably 1 to 5, and especially positive integers from 1 to 3. and For each X i = 1 to p and 1 to q i 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- is selected independently, preferably the group consisting of -CH2-CH2-O-, -CH2-CH(CH3)-O-, and -CH(CH3)-CH2-O-, and particularly preferably -CH2-CH2-O-.

[0013] Such coolants (as a 50% aqueous solution) have a target conductivity of 150 µS / cm to 3000 µS / cm, preferably 175 µS / cm to 2750 µS / cm, and more preferably 200 µS / cm to 2500 µS / cm at 25°C according to ASTM D 1125.

[0014] This type of conductivity makes the coolant according to the invention suitable not only for cooling systems of vehicles with internal combustion engines, but also for cooling systems of vehicles with electric motors and hybrid motors with a combination of combustion and electric motors.

[0015] Suitable electric vehicles are fully electric vehicles and hybrid electric vehicles. Electric vehicles typically include a rotating electric motor and an energy storage device configured to store electricity used to drive the rotating electric motor. Hybrid vehicles typically operate by using power from both a rotating electric motor and a combustion engine.

[0016] Suitable hybrid electric vehicles are full hybrid (also known as strong hybrid) electric vehicles, plug-in hybrid (also known as PHEV) electric vehicles, or range-extended electric vehicles (also known as REEVs). Full hybrid electric vehicles are typically vehicles that can operate solely on a combustion engine, solely on an electric motor, or a combination of both. Plug-in hybrid electric vehicles are typically hybrid electric vehicles with a rechargeable battery that can be fully charged by plugging it into an external power source.

[0017] The preferred type of electric vehicle is the battery electric vehicle (also known as a BEV). A BEV is typically an electric vehicle that uses chemical energy stored in a rechargeable battery pack and is propelled by an electric motor and motor controller instead of an internal combustion engine.

[0018] The term "vehicle" refers to any mobile or stationary platform, with a mobile platform being preferred. In particular, a vehicle is selected from passenger vehicles, light or heavy trucks, multi-purpose vehicles, agricultural vehicles, industrial or warehouse vehicles, or recreational off-road vehicles.

[0019] Therefore, one advantage of the coolant according to the invention is that automakers do not need to stock different coolants for vehicles with combustion engines and electric engines, but can use one type of coolant for all vehicles.

[0020] The coolant compounds according to the present invention are described in more detail below: (A) Antifreeze As the antifreeze (A) according to the invention, one or more compounds selected from the group consisting of 1,2-ethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerol, or their dimers, trimers or oligomers, or their monoalkyl ethers or dialkyl ethers are used.

[0021] Preferred are 1,2-ethylene glycol or 1,2-propanediol, or their dimers, trimers or oligomers, or their monoalkyl ethers or dialkyl ethers.

[0022] 1,2-ethylene glycol or 1,2-propanediol are particularly preferred, especially 1,2-ethylene glycol.

[0023] 1,2-propanediol and its derivatives are preferred. Derivatives of 1,2-propanediol may be polymers and oligomers, as well as monoalkyl or dialkyl ethers of 1,2-propanediol, and their polymers and oligomers.

[0024] More preferably, 1,2-ethylene glycol and its derivatives are used. Derivatives of 1,2-ethylene glycol can be polymers and oligomers, as well as monoalkyl or dialkyl ethers of 1,2-ethylene glycol, and their polymers and oligomers. Examples include diethylene glycol, triethylene glycol, diethylene glycol mono-C1-C4 alkyl ethers, and triethylene glycol mono-C1-C4 alkyl ethers, even more preferably 1,2-ethylene glycol, diethylene glycol, and triethylene glycol, most preferably 1,2-ethylene glycol or diethylene glycol, and especially 1,2-ethylene glycol.

[0025] The dimers, trimers, or oligomers of the alkylene glycols mentioned are dialethylene glycols, trialkylene glycols, tetraalkylene glycols, and their higher homologues with molecular weights up to 598 g / mol.

[0026] Preferred are monomeric alkylene glycols and their dimers or trimers, more preferably monomeric alkylene glycols and their dimers, and particularly preferred are monomeric alkylene glycols.

[0027] The monoalkyl or dialkyl ethers of the above-mentioned alkylene glycols and their polymers and oligomers are preferably mono- or di-C1- to C4-alkyl ethers, more preferably mono-C1- to C4-alkyl ethers, and even more preferably methyl ethers, ethyl ethers or n-butyl ethers, especially monomethyl ethers, monoethyl ethers or monon-butyl ethers.

[0028] In the context of this document, the phrase “C1- to C4-alkyl” represents methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl, preferably methyl, ethyl, n-propyl, n-butyl, isobutyl, and tert-butyl, more preferably methyl, ethyl, and n-butyl.

[0029] The preferred compound (A) is selected from the group consisting of: monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene 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, used alone or as a mixture thereof in each case.

[0030] Preferably, compound (A) is 1,2-ethylene glycol or 1,2-propanediol, especially 1,2-ethylene glycol.

[0031] (B) Water The water used in the coolant according to the invention should be ion-free, meaning water with a neutral pH value, and substantially free of other ions except for hydroxide ions and hydrated hydrogen ions produced by the proton autotransmission of water at the corresponding temperature.

[0032] The conductivity of the deionized water used at 25°C (as determined throughout this document according to ASTM D 1125) should preferably not exceed 5 µS / cm, more preferably not exceed 3 µS / cm, even more preferably not exceed 2 µS / cm, and especially not exceed 1 µS / cm.

[0033] The deionized water used can be pure distilled water, double-distilled water, or deionized water, for example, through ion exchange, preferably through ion exchange of at least its cations, and more preferably through ion exchange of both cations and anions.

[0034] (C1) 2-Thiothiazole At least one 2-thiothiazole of general formula (I) (C1) Where variable R1 is represented by equation -(C) m H 2m The )-COOX is a carboxyl alkyl group, wherein m is 1 to 4 and X is hydrogen, an alkali metal cation, an ammonium cation or a substituted ammonium cation, and variables R2 and R3 are each independently hydrogen or C1-C4-alkyl groups, wherein R2 and R3 together with the two ring carbon atoms of the thiazole ring to which they are attached can also form a five- or six-membered saturated or unsaturated ring.

[0035] The preferred type is benzothiazole of general formula (III). in The variable R is hydrogen or C1-C10 Alkyl groups, especially methyl or ethyl, and The variable R' is -SR 1 .

[0036] Preferred are (2-benzothiazolylthio)acetic acid (R=H, R'=-S-CH2-COOH) or (2-benzothiazolylthio)propionic acid (R=H, R'=-S-CH2-CH2-COOH), especially (2-benzothiazolylthio)acetic acid.

[0037] (C2) is different from (C1) azole derivatives The coolant according to the invention may optionally further comprise at least one azole derivative (C2) different from (C1).

[0038] In the context of this specification, azole derivatives mean a five-membered heterocyclic compound having two or three heteroatoms selected from the group consisting of nitrogen and sulfur, and containing no sulfur atom or containing at most one sulfur atom, and may have an aromatic or saturated six-membered fused ring.

[0039] 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.

[0040] The preferred group of specified azole derivatives are fused imidazoles and fused 1,2,3-triazoles of the following general formula. (1) Or (2) in The variable R is hydrogen or C1-C 10 Alkyl groups, especially methyl or ethyl, and Variable X is a nitrogen atom or a CH group.

[0041] Typical and preferred examples of azole derivatives of general formula (1) are benzimidazole (X=CH, R=H), benzotriazole (X=N, R=H), and methylbenzotriazole (toluidine triazole) (X=N, R=CH3). A typical example of azole derivatives of general formula (2) is hydrogenated 1,2,3-methylbenzotriazole (toluidine triazole) (X=N, R=CH3).

[0042] Another preferred group of the specified azole derivatives is benzothiazole of general formula (3). in The variable R is defined as above, and Variable R' is hydrogen, C1-C 10Alkyl groups, particularly methyl or ethyl, or particularly thiol groups (-SH). A typical example of an azole derivative of general formula (3) is 2-mercaptobenzothiazole.

[0043] Another suitable azole derivative is the non-fused azole derivative of general formula (4). (4) in Variables X and Y together are two nitrogen atoms or One nitrogen atom and a CH group, For example, 1H-1,2,4-triazole (X=Y=N) or preferably imidazole (X=N, Y=CH).

[0044] For the purposes of this invention, benzimidazole, benzotriazole, methylbenzotriazole, hydrogenated methylbenzotriazole, or mixtures thereof, especially benzotriazole or methylbenzotriazole, are particularly preferred as azole derivatives.

[0045] (D) Inorganic salts The inorganic salt (D) is at least one inorganic salt that serves as an additional corrosion inhibitor, wherein the at least one inorganic salt is selected from the group consisting of molybdate, borate, vanadate, tungstate and antimonate, preferably from the group consisting of molybdate, borate and vanadate, more preferably from the group consisting of molybdate, borate and vanadate, and even more preferably molybdate.

[0046] As molybdates, alkali metal salts, ammonium salts, or substituted ammonium salts of molybdate H₂MoO₄, or the acid itself, are commonly used, where the alkali metal salt, ammonium salt, or substituted ammonium salt has the meaning indicated above. Typical representatives of such molybdates (C) are sodium molybdate and potassium molybdate.

[0047] Borates are typically used in the form of sodium tetraborate (borax).

[0048] In a preferred embodiment, the coolant according to the invention does not contain silicon-containing substances. This refers to both inorganic silicates and organic silicon-containing compounds, such as esters of orthosilicic acid.

[0049] (E) phosphate As an optional compound (D), at least one inorganic phosphate is used as an additional corrosion inhibitor.

[0050] Typically, alkali metal salts, ammonium salts, or substituted ammonium salts of orthophosphoric acid (H3PO4) or the acid itself are used, wherein the alkali metal salt, ammonium salt, or substituted ammonium salt has the meaning indicated above. However, component (E) will generally be present entirely or primarily in the coolant of the invention in salt form, which typically has a pH of 4 to 11, particularly 7 to 11. When free orthophosphoric acid is used, ammonia or a suitable amine is typically converted to the desired salt by means of sodium hydroxide or potassium hydroxide. Other suitable components (E) are alkali metal salts, ammonium salts, or substituted ammonium salts of diphosphoric acid, metaphosphoric acid, pyrophosphoric acid, and / or polyphosphoric acid, or these acids themselves, wherein the alkali metal salt, ammonium salt, or substituted ammonium salt has the meaning indicated above. Mixtures of the mentioned salts and / or acids are also possible. Typical representatives of such phosphates (E) are sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium diphosphoric acid, tetrasodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate, and similar potassium salts.

[0051] (F) carboxylic acid The coolant according to the invention further comprises at least one aliphatic, cycloaliphatic or aromatic monocarboxylic acid (F1), dicarboxylic acid or tricarboxylic acid (F2), in the form of an alkali metal salt, ammonium salt or substituted ammonium salt, having 3 to 21 carbon atoms in the acid moiety.

[0052] (F1) Aliphatic, cycloaliphatic or aromatic, preferably aliphatic or aromatic, and very preferably aliphatic monocarboxylic acid, having 3 to 16 carbon atoms in each case, in the form of an alkali metal salt, an ammonium salt or a substituted ammonium salt; (F2) Aliphatic or aromatic dicarboxylic acid or tricarboxylic acid, preferably dicarboxylic acid, even more preferably aliphatic dicarboxylic acid, having 3 to 21 carbon atoms in each case, in the form of an alkali metal salt, an ammonium salt or a substituted ammonium salt.

[0053] Possible straight-chain or branched aliphatic or cyclic aliphatic, preferably aliphatic, monocarboxylic acids of group (F1) include, for example, propionic acid, valeric acid, hexanoic acid, cyclohexylacetic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, decanoic acid, neodecanoic acid, undecanoic acid, or dodecanoic acid. Suitable aromatic monocarboxylic acids of group (F1) include, in particular, benzoic acid and, for example, C1-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 or p-(hydroxymethyl)benzoic acid), or halobenzoic acids (such as o-fluorobenzoic acid, m-fluorobenzoic acid, or p-fluorobenzoic acid).

[0054] 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-tetramethylpentanoic acid as its major 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% of 3,5,5-trimethylhexanoic acid as its major component, and even more preferably, the major component is more than 95% of 3,5,5-trimethylhexanoic acid.

[0055] The preferred choices are 2-ethylhexanoic acid, nonanoic acid (nonanoic acid), and isononanoic acid. Typical examples of dicarboxylic or tricarboxylic acids in group (F2), preferably dicarboxylic acids, and more preferably aliphatic dicarboxylic acids, are malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid (octanoic acid), undecanoic acid, dodecanoic acid, cyclopentadiene dicarboxylic acid, terephthalic acid, phthalic acid, and triazine triiminoiminocarboxylic acids (such as 6,6',6"-(1,3,5-triazinyl-2,4,6-triyltriimino)trihexanoic acid). Among these, aliphatic individuals are particularly preferred.

[0056] Adipic acid and sebacic acid (octanoic acid) are preferred.

[0057] The aforementioned carboxylic acid (F) is typically present entirely or primarily as an alkali metal salt, ammonium salt, or substituted ammonium salt as defined above, even when these salts are added as free acids in the production of the antifreeze concentrate of the present invention, because the concentrate typically has a pH of 4 to 11, particularly 7 to 11, more preferably 7 to 10, and even more preferably 7.5 to 9.5. The component (F) used as the free carboxylic acid is typically converted from ammonia or a suitable amine into the desired salt using sodium hydroxide or potassium hydroxide, preferably using sodium hydroxide or potassium hydroxide.

[0058] In one embodiment, at least one aliphatic monocarboxylic acid is present in the coolant of the present invention.

[0059] In another embodiment, at least one aliphatic dicarboxylic acid is present in the coolant according to the invention.

[0060] In a preferred embodiment, a mixture of at least one aliphatic monocarboxylic acid and at least one aliphatic dicarboxylic acid is present in the coolant according to the invention.

[0061] (G)alkylamines The other component is at least one alkylamine of general formula (II). in R 4 It is an organic group having 6 to 10 carbon atoms, particularly 6 to 10 carbon atoms, preferably 7 to 9 carbon atoms, and especially preferably 8 carbon atoms, of alkyl or alkenyl groups. p and q are each independently of each other and are 1 to 20, preferably 1 to 15, particularly preferably 1 to 10, very particularly preferably 1 to 5, especially 1 to 3, especially 1 to 2, and even positive integers of 1. and For each X i = 1 to p and 1 to q i 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- is selected independently, preferably the group consisting of -CH2-CH2-O-, -CH2-CH(CH3)-O-, and -CH(CH3)-CH2-O-, and particularly preferably -CH2-CH2-O-.

[0062] It should be noted that compounds of formula (II) are generally reaction mixtures having a product composition distribution that depends on the reaction conditions. Therefore, the chain-[-X] i The length of -]- follows a distribution about the statistical mean, such that the values ​​of p and q can be distributed about the statistical mean. Therefore, for each individual compound in equation (II), the values ​​of p and q are positive integers, but for the reaction mixture, they can also have non-integer values ​​on the statistical mean.

[0063] In the compound of formula (II), the structural element R 4-N is preferably derived from aliphatic amines, which are preferably obtained by hydrogenation and amination of fatty acids and esters, particularly preferably by hydrogenation and amination of the aforementioned fatty acids or amination of the aforementioned fatty alcohols. The same applies to aliphatic amines as to fatty alcohols.

[0064] As a group R 4 Alkyl groups are preferred over alkenyl groups.

[0065] In a preferred embodiment, the fatty amine is n-hexylamine, 2-methylpentylamine, n-heptylamine, 2-heptylamine, isoheptylamine, 1-methylhexylamine, n-octylamine, 2-ethylhexylamine, 2-aminooctylamine, 6-methyl-2-heptylamine, n-nonylamine, isononylamine, n-decylamine, and 2-propylheptylamine or a mixture thereof.

[0066] Hexylamine, octylamine, 2-ethylhexylamine and decylamine are particularly preferred, with octylamine and 2-ethylhexylamine, especially octylamine, being particularly preferred.

[0067] Of particular note are the di-, tri-, and tetra-ethoxylated n-octylamine and the di-, tri-, and tetra-ethoxylated n-hexylamine.

[0068] In alkoxylated amines of general formula (II), the degree of alkoxylation refers to the sum (p+q), that is, the average total number of alkoxylated units per molecule of amine.

[0069] Compound (II) is preferably capable of causing the corresponding amine R to... 4 -NH2 is preferably reacted with epoxides under alkaline conditions to obtain the desired average statistical degree of alkoxylation. When structural unit X... i It is derived from ethylene oxide or propylene oxide, preferably from ethylene oxide, which is particularly preferred.

[0070] (H) Other additives Other typical coolant additives may be added to the coolant of this invention.

[0071] As another conventional additive, the coolant of the present invention may also contain a conventional small amount of defoamer (usually in an amount of 0.002% to 0.008% by weight), and for hygiene and safety reasons in the event of swallowing, it also contains a bitter substance (e.g., benzodiazepine type, usually in an amount of 0.005% to 0.02% by weight).

[0072] In addition, the coolant may contain dyes (typically in amounts of 0.001% to 0.005% by weight) and hard water stabilizers (typically in amounts of 0.1% to 0.5% by weight), such as copolymers based on polyacrylic acid, polymaleic acid, acrylic acid-maleic acid copolymers, polyvinylpyrrolidone, polyvinylimidazole, vinylpyrrolidone-vinylimidazole copolymers and / or copolymers of unsaturated carboxylic acids and olefins.

[0073] composition The coolant according to the present invention has the following composition: (A) 45% to 65% by weight of at least one antifreeze agent, preferably 50% to 60% by weight, more preferably 50% to 55% by weight. (B) 30% to 50% by weight of water, preferably 35% to 50% by weight, more preferably 40% to 50% by weight. (C1) 0.01% to 0.5% by weight of at least one 2-thiothiazole of general formula (I), preferably 0.02% to 0.4% by weight, more preferably 0.05% to 0.2% by weight. (C2) at least one azole derivative different from (C1) of 0% to 0.75% by weight, preferably 0.02% to 0.5% by weight, more preferably 0.05% to 0.25% by weight. (D) 0.01% to 0.75% by weight of at least one inorganic salt as an additional corrosion inhibitor, preferably 0.02% to 0.5% by weight, more preferably 0.05% to 0.3% by weight. (E) At least one inorganic phosphate, from 0% to 2% by weight, preferably from 0.01% to 1.5% by weight, more preferably from 0.01% to 1.0% by weight. (F) 0.1% to 2% by weight of at least one aliphatic, cyclic aliphatic, or aromatic monocarboxylic acid, dicarboxylic acid, or tricarboxylic acid, preferably 0.5% to 1.75% by weight, more preferably 1.0% to 1.5% by weight, and (G) 0.5% to 2.0% by weight of at least one alkylamine of general formula (II), preferably 0.75% to 1.75% by weight, more preferably 1.0% to 1.75% by weight. (H)Optionally select other additives from the group consisting of defoamers, bittering substances and hard water stabilizers. The condition is that the total of all components always adds up to 100 by weight.

[0074] The coolant described is typically used at the end-user level, i.e., for refilling the vehicle's cooling system.

[0075] Coolant is typically obtained by diluting a coolant concentrate with water (B). Therefore, another subject of this invention is a coolant concentrate that typically contains little or no water (B): The composition of the coolant concentrate according to the present invention is as follows: (A) 80% to 95% by weight of at least one antifreeze agent, preferably 80% to 90% by weight, more preferably 85% to 95% by weight. (B) 0% to 10% by weight of water, preferably 0% to 8% by weight, more preferably 0% to 5% by weight. (C1) 0.02% to 1.0% by weight of at least one 2-thiothiazole of general formula (I), preferably 0.04% to 0.8% by weight, more preferably 0.1% to 0.4% by weight. (C2) at least one azole derivative different from (C1) of 0% to 1.5% by weight, preferably 0.04% to 1.0% by weight, more preferably 0.1% to 0.5% by weight. (D) 0.02% to 1.5% by weight of at least one inorganic salt as an additional corrosion inhibitor, preferably 0.2% to 1.0% by weight, more preferably 0.1% to 0.6% by weight. (E) At least one inorganic phosphate, from 0% to 4.0% by weight, preferably from 0.02% to 3.0% by weight, more preferably from 0.02% to 2.0% by weight. (F) 0.2% to 4% by weight of at least one aliphatic, cyclic aliphatic, or aromatic monocarboxylic acid, dicarboxylic acid, or tricarboxylic acid, preferably 1.0% to 3.5% by weight, more preferably 2.0% to 3.0% by weight, and (G) 1.0% to 4.0% by weight of at least one alkylamine of general formula (II), preferably 1.5% to 3.5% by weight, more preferably 2.0% to 3.5% by weight. The condition is that the total of all components always adds up to 100 by weight.

[0076] Coolant is typically obtained by diluting concentrate with water (B) at a ratio of 1:0.75 to 1:1.5 (v / v).

[0077] Another embodiment of the invention is a coolant superconcentrate. The coolant concentrate is typically obtained by diluting a coolant superconcentrate with glycol (A), and the coolant can be obtained by diluting the coolant superconcentrate with glycol (A) and water (B), respectively. Therefore, the coolant superconcentrate typically contains little or no water (B) and contains less ethylene glycol than the concentrate. In the concentrate or superconcentrate, glycol (A) acts as a solvent for the other components and can therefore be present in a higher quantity.

[0078] The composition of the ultra-concentrated coolant according to the present invention is as follows: (A) 20% to 90% by weight of at least one antifreeze agent, preferably 30% to 85% by weight, more preferably 40% to 80% by weight. (B) 0% to 10% by weight of water, preferably 0% to 8% by weight, more preferably 0% to 5% by weight. (C1) 0.03% to 1.5% by weight of at least one 2-thiothiazole of general formula (I), preferably 0.06% to 1.4% by weight, more preferably 0.15% to 0.6% by weight. (C2) at least one azole derivative different from (C1) of 0% to 2.25% by weight, preferably 0.06% to 1.5% by weight, more preferably 0.15% to 0.75% by weight. (D) 0.03% to 2.25% by weight of at least one inorganic salt as an additional corrosion inhibitor, preferably 0.3% to 1.5% by weight, more preferably 0.15% to 0.9% by weight. (E) At least one inorganic phosphate, from 0% to 6.0% by weight, preferably from 0.03% to 4.5% by weight, more preferably from 0.03% to 3.0% by weight. (F) 0.3% to 6% by weight of at least one aliphatic, cyclic aliphatic, or aromatic monocarboxylic acid, dicarboxylic acid, or tricarboxylic acid, preferably 1.5% to 5.25% by weight, more preferably 3.0% to 4.5% by weight, and (G) 1.5% to 6.0% by weight of at least one alkylamine of general formula (II), preferably 2.25% to 5.25% by weight, more preferably 3.0% to 5.25% by weight. The condition is that the total of all components always adds up to 100 by weight.

[0079] The advantages of the coolants of this invention are that they not only exhibit high tolerance to the residues of fluoroaluminate flux in welded aluminum radiators, but also exhibit high corrosion inhibition, especially against corrosion of ferrous and aluminum alloys as well as non-ferrous alloys.

[0080] Therefore, another aspect of the invention is the use of the coolant according to the invention in a cooling system that is at least partially, preferably primarily, or solely made of aluminum or aluminum alloy.

[0081] Compared with the coolant according to EP 2956520 B1, the conductivity is reduced while maintaining its anti-corrosion activity.

[0082] Example Unless otherwise specified, conductivity is determined according to ASTM D 1125 at 25°C and is expressed in µS / cm throughout the text.

[0083] Corrosion testing was performed on a GAlSi6Cu4 specimen at 88°C for 336 hours (14 days) according to ASTM D 1384. The corrosion rate was expressed in mg / cm³. 2 Provided.

[0084] The corrosion test according to ASTM D 4340 is a standard test used to determine the corrosion susceptibility of aluminum or aluminum alloys in cooling systems used in internal combustion engines. The standard apparatus used for this purpose simulates the aluminum-containing hot internal surface of the cooling circuit of an internal combustion engine. An aluminum test plate is heated as follows, with its upper surface in contact with the cooling fluid to be tested. The test temperature is 135°C. After a 168-hour placement test period, the corrosion of the plate is visually estimated, and the weight change is determined by weighing (after pickling). The standard sample block is GAlSi6Cu4, and the corrosion rate is expressed in mg / cm³. 2 Provided.

[0085] Conductivity was measured in 50% aqueous solution.

[0086] According to ASTM D1384, corrosion testing is conducted in a 33.3% aqueous solution in the presence of "corrosive water" for 336 hours, following the test procedure. According to ASTM D4340 corrosion test, the test is conducted for 168 hours in a 25% aqueous solution in the presence of "corrosive water" following the test procedure. As a comparative example, a coolant similar to KM3 of EP 2956520 B1 was used, but without tetraalkoxysilane as in Comparative Example 1.

[0087] The coolant also contains commercially available defoamers, hard water stabilizers, dyes, and bittering substances. *) as a 50% aqueous solution.

[0088] As a target, the conductivity of the 50% aqueous solution was set to 2400 µS / cm. The coolant according to Comparative Example 1 was diluted with monoethylene glycol until the desired conductivity was achieved (approximately 35% by volume of Comparative Example 1 was diluted with 65% by volume of monoethylene glycol). It is readily apparent that simply diluting the coolant of Comparative Example 1 with monoethylene glycol to achieve the desired conductivity results in insufficient corrosion inhibition of the coolant.

[0089] Therefore, the amount of corrosion inhibitors (sebacic acid, methylbenzotriazole, and (2-benzothiazolylthio)acetic acid) was increased and n-octyl diethanolamine was added: It is easy to see that using a higher amount of n-octyldiethanolamine can improve corrosion inhibition without significantly affecting conductivity. *) The corrosion test duration according to ASTM D1384 is only 7 days. It is easy to see that good corrosion resistance can be achieved even without phosphates; however, even a small amount of phosphates is beneficial.

Claims

1. A coolant, the coolant comprising (A) At least one antifreeze agent, said at least one antifreeze agent being selected from 1,2-ethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerol, their dimers, trimers or oligomers, and their monoalkyl or dialkyl ethers. (B) Water (C1) At least one 2-thiothiazole of general formula (I) Where variable R1 is represented by equation -(C m H 2m The )-COOX group is a carboxyl alkyl group, wherein m is 1 to 4 and X is hydrogen, an alkali metal cation, an ammonium cation, or a substituted ammonium cation, and variables R2 and R3 are each independently hydrogen or C1-C4-alkyl groups, wherein R2 and R3, together with the two ring carbon atoms of the thiazole ring to which they are attached, can also form a five- or six-membered saturated or unsaturated ring. (C2) optionally at least one azole derivative different from (C1), (D) At least one inorganic salt selected from the group consisting of molybdates, borates, vanadates, tungstates, and antimonates as an additional corrosion inhibitor. (E) At least one inorganic phosphate, optionally used as another corrosion inhibitor. (F) At least one aliphatic, cyclic aliphatic, or aromatic monocarboxylic acid, dicarboxylic acid, or tricarboxylic acid, in the form of an alkali metal salt, ammonium salt, or substituted ammonium salt, having 3 to 21 carbon atoms in the acid moiety, and (G) At least one alkylamine of general formula (II) in R 4 It is an organic group having 6 to 10 carbon atoms, particularly 6 to 10 carbon atoms, preferably 7 to 9 carbon atoms, and especially preferably 8 carbon atoms, of alkyl or alkenyl groups. p and q are each independent of each other and are 1 to 20, preferably 1 to 15, particularly preferably 1 to 10, very particularly preferably 1 to 5, and especially positive integers from 1 to 3. and For each X i = 1 to p and 1 to q i 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- is selected independently, preferably the group consisting of -CH2-CH2-O-, -CH2-CH(CH3)-O-, and -CH(CH3)-CH2-O-, and particularly preferably -CH2-CH2-O-.

2. The coolant according to claim 1, wherein the coolant comprises (A) 45% to 65% by weight of at least one antifreeze agent. (B) 30% to 50% by weight of water, (C1) 0.01% to 0.5% by weight of at least one 2-thiothiazole of general formula (I), (C2) 0% to 0.75% by weight of at least one azole derivative different from (C1), (D) 0.01% to 0.75% by weight of at least one inorganic salt as an additional corrosion inhibitor. (E) 0% to 2% by weight of at least one inorganic phosphate. (F) 0.1% to 2% by weight of at least one aliphatic, cyclic aliphatic or aromatic monocarboxylic acid, dicarboxylic acid or tricarboxylic acid, and (G) 0.5% to 2.0% by weight of at least one alkylamine of general formula (II), (H)Optionally select other additives from the group consisting of defoamers, bittering substances and hard water stabilizers. The condition is that the total of all components always adds up to 100 by weight.

3. The coolant according to any one of the preceding claims, wherein the coolant, as a 50% aqueous solution, has a conductivity of 150 µS / cm to 3000 µS / cm at 25°C according to ASTM D 1125.

4. The coolant according to any one of the preceding claims, wherein the antifreeze (A) is selected from the group consisting of 1,2-ethylene glycol and 1,2-propanediol, preferably 1,2-ethylene glycol.

5. The coolant according to any one of the preceding claims, wherein the 2-thiothiazole (C1) of the general formula (I) is selected from (2-benzothiazolylthio)acetic acid and 3-(2-benzothiazolylthio)propionic acid, or their alkali metal salts, ammonium salts or substituted ammonium salts.

6. The coolant according to any one of the preceding claims, wherein at least one azole derivative (C2) different from (C1) is present, and is selected from the group consisting of benzotriazole, methylbenzotriazole (toluidine triazole) and hydrogenated methylbenzotriazole, preferably selected from the group consisting of benzotriazole and methylbenzotriazole.

7. The coolant according to any one of the preceding claims, wherein the at least one inorganic salt (D) is selected from the group consisting of molybdate, borate, vanadate and tungstate, preferably selected from the group consisting of molybdate, borate and vanadate, more preferably selected from the group consisting of molybdate, borate and vanadate, and even more preferably molybdate.

8. The coolant according to any one of the preceding claims, wherein at least one inorganic phosphate (E) is present.

9. The coolant according to any one of the preceding claims, wherein the at least one carboxylic acid comprises at least one aliphatic monocarboxylic acid, preferably selected from the group consisting of 2-ethylhexanoic acid, nonanoic acid (nonanoic acid) and isononanoic acid.

10. The coolant according to any one of the preceding claims, wherein the at least one carboxylic acid comprises at least one aliphatic dicarboxylic acid, preferably selected from the group consisting of adipic acid and sebacic acid.

11. The coolant according to any one of the preceding claims, wherein a mixture of at least one aliphatic monocarboxylic acid and at least one aliphatic dicarboxylic acid is present.

12. The coolant according to any one of the preceding claims, wherein the alkylamine (G) is selected from the group consisting of ethoxylated n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine, n-nonylamine and isononylamine, preferably selected from the group consisting of ethoxylated n-hexylamine, n-octylamine and 2-ethylhexylamine, and more preferably ethoxylated n-octylamine.

13. The coolant according to claim 12, wherein the degree of ethoxylation of the alkylamine is 2 to 4, preferably 2 to 3, and more preferably 2.

14. Use of the coolant according to any one of the preceding claims in the cooling system of a vehicle equipped with an internal combustion engine, an electric engine or a hybrid engine.

15. The use according to claim 14, wherein the cooling system is at least partially, preferably primarily, or solely made of aluminum or an aluminum alloy.

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