New coolant compositions

Abstract

The present invention relates to novel coolant compositions based on freezing point-lowering liquids as main constituent, specific alkoxy aminoalkylsilane organic compounds as corrosion inhibitors, and also further corrosion inhibitors which are different therefrom. The present invention further relates to a new application of the coolant compositions in cooling systems with Internal Combustion Engine, battery, E-motors, control unit, etc. for automobiles and stationary platforms.

Description

[0001] DESCRIPTION

[0002] NEW COOLANT COMPOSITIONS

[0003] The present invention relates to novel coolant compositions based on freezing point-lowering liquids as main constituent, specific alkoxy aminoalkylsilane organic compounds as corrosion inhibitors, and also further corrosion inhibitors which are different therefrom.

[0004] Coolant compositions for the cooling apparatuses (which are usually configured as cooling circuits) of Internal Combustion Engines (ICE) for automobiles and stationary platforms, for example, automobiles usually comprise alkylene glycols such as monoethylene glycol (MEG) or monopropylene glycol (MPG), optionally in admixture with glycerol, as antifreeze component which lowers the freezing point of the coolant composition. Apart from further components such as antifoams, dyes or bitter substances, corrosion inhibitors, in particular, are comprised.

[0005] Especially in modern ICE, temperatures which place severe demands on the materials used are reached. Any type and any extent of corrosion represent a potential risk factor which can lead to shortening of the life of the engine and to a decrease in reliability. Furthermore, a number of different materials, for example cast iron, copper, brass, soft solder, steel and also aluminium, aluminium alloys and magnesium alloys, are increasingly being used in modern engines. This plurality of metallic materials additionally results in potential corrosion problems, in particular at the places where different metals are in contact with one another. Various types of corrosion such as pit corrosion, crevice corrosion, erosion or cavitation can occur comparatively easily at such places in particular.

[0006] Metallic components and metal surfaces of cooling systems often contain nitrites, such as sodium or potassium nitrite from metalworking fluids. As a result, the coolant in the cooling system comes into contact with these nitrites. However, nitrites react with secondary amines, especially under acidic conditions, to form nitrosamines, which are highly toxicologically concerning and suspected to cause cancer. The formation of nitrosamines must be prevented or at least reduced to a minimum, in order to e.g. protect workshop personnel from health damage when handling used coolant.

[0007] The Bundesanstalt fiir Arbeitsschutz und Arbeitsmedizin, Ausschuss fur Gefahrstoffe, (Federal Institute for Occupational Safety and Health, Committee on Hazardous Substances), has issued regulations for handling carcinogenic N-nitrosamines in the Technischen Regeln fiir Gefahrstoffe (Technical Rules for Hazardous Substances, TRGS 552, September 2018 edition). This includes a list of secondary amines which form carcinogenic N-nitrosamines, including diethanolamine.

[0008] Coolants often contain tertiary amines, for example, as corrosion inhibitors. Due to manufacturing conditions, such tertiary amines often contain a small amount of secondary amines that are capable of reacting with nitrites to form nitrosamines:

[0009] They usually are produced by the reaction of nitrous acid (HNO2, HO-N=O) and secondary amines (R2NH):

[0010] HO-N=O + R2NH R2N-N=O + H2O

[0011] The nitrous acid usually arises from protonation of a nitrite. Other sources of nitrosyl cations may have the same effect, see e.g. the list of chemical compounds in the above-mentioned TRGS 552, paragraph 2 (3).

[0012] The coolant compositions likewise have to be compatible with non-metallic constituents of the cooling apparatuses, for example elastomers and plastics from hose connections or seals, and must not change their physical properties. Furthermore, the type of coolant composition is of critical importance for heat transfer in modern ICE. These requirements for the cooling apparatuses of ICE are also applicable for the cooling apparatuses of New Energy Vehicle (NEV). In principle, NEV can be classified as Battery Electrical Vehicle (BEV), Hybrid Electrical Vehicle (HEV), Plug-in Hybrid Electrical Vehicle (PHEV), Ranger Extender Electrical Vehicle (REEV), Fuel Cell Electrical Vehicle (FCEV) etc.

[0013] In addition, conventional engine coolants (electrical conductivity between 3000-6000 ps / cm at 25 °C) are being widely used in the cooling apparatuses of NEV. However, in some conditions like battery package failure, car crash and other physical damage, these coolants may get in close contact with battery cell. Under the voltage of 400V or 800V of the vehicle or other future battery developments, the water / glycol based conventional coolants can readily result in short-circuits, also can be easily electrolyzed to generate Hydrogen( flammable) and Oxygen ( in favor of flame) , which could lead to a thermal runaway, fire or even explosion finally. Additionally, battery, E-motor and control unit in stationary platforms like battery swap stations, charging stations, etc. will also meet the same safety issues that need to be taken care of in certain scenarios. Low Electrical Conductivity Coolant (LECC) is believed to alleviate the risk of thermal runaway and other dangerous scenarios.

[0014] In classical coolants, typically inorganic bases such as sodium hydroxide or potassium hydroxide are used, which is discouraged in Low Electrical Conductivity Coolants, as the inorganic bases significantly increase the electrical conductivity.

[0015] Therefore, the use of amines in coolants with low electrical conductivity is advantageous as it allows for the adjustment of reserve alkalinity and pH without significantly increasing the electrical conductivity.

[0016] EP 2956520 B1 discloses coolant concentrates comprising - inter alia - contain 2-thiothiazole derivatives bearing a carboxyalkyl radical.

[0017] Such sulphur-containing inhibitors provide excellent inhibition of aluminium corrosion even in the presence of potassium fluoroaluminates.

[0018] However, it is a disadvantage that the coolants according to EP 2956520 B1 exhibit a high electrical conductivity.

[0019] The unpublished International Application with the application number PCT / CN2024 / 084849 and the filing date 29 March 2024 discloses Low Electrical Conductivity Coolants comprising - inter alia - at least one organosilicon compound, comprising at least one alkoxy aminoalkylsilane and at least one organic amine, wherein the description lists primary, secondary and tertiary amines, with preference to secondary amines such as diethanolamine and diisopropanolamine.

[0020] However, in view of the above-mentioned mechanism for the formation of nitrosamines the use of secondary amines is strongly discouraged.

[0021] Therefore, it was an object of the present invention to provide coolant compositions with low electrical conductivity in which the formation of nitrosamines is reduced.

[0022] The coolants according to the invention have to fulfil the general requirements according to ASTM D3306, inter alia the corrosion test according to ASTM D1384 or equivalent Chinese National standard GB 29743.1-2022 as well as GB 29743.2-20XX (Published in Jan. 2024 for public opinion).

[0023] The object was achieved by the use of novel coolants (coolant compositions), comprising

[0024] (A) at least one antifreezing agent selected from the group consisting of 1 ,2-ethylene glycol, 1 ,2-propylene glycol, 1 ,3-propylene glycol, glycerol, dimers, trimers or oligomers thereof, and mono- or dialkyl ethers thereof

[0025] (B) water (C2) at least one azol derivative different from (C1),

[0026] (C1) optionally additionally to azol derivative (C2) at least one 2-thiothiazole of the general formula (I) where the variable R1 is a carboxyalkyl radical of the formula -(CmH2m)-C00X, where m is from 1 to 4 and X is hydrogen, an alkali metal cation, an ammonium cation or a substituted ammonium cation, and the variables R2 and R3 are each, independently of one another, hydrogen or a Ci-C4-alkyl group, where R2 and R3 together with the two ring carbon atoms of the thiazole ring to which they are attached may also form a five- or six-membered saturated or unsaturated ring,

[0027] (D) optionally at least one inorganic salt as further corrosion inhibitor selected from the group consisting of molybdates, borates, silicates, vanadates, tungstates, and antimonates,

[0028] (E) optionally at least one organosilicon compound selected from the group consisting of

[0029] - esters of orthosilicic acid (E1) and

[0030] - alkoxy alkylsilanes (E2),

[0031] (F) optionally at least one aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acid as acid or in the form of alkali metal, ammonium or substituted ammonium salts thereof having from 3 to 21 carbon atoms in the acid part, preferably at least one monocarboxylic acid combined with one dicarboxylic acid, and

[0032] (G) at least one organic tertiary amine, and

[0033] (H) at least one organic compound with at least one primary amino group in cooling systems comprising at least one metal component which was previously in contact with nitrites.

[0034] The present invention is based on the observation that the formation of nitrosamines is suppressed to a large extent by the use of at least one compound (H). It is possible to reduce the formation of nitrosamines (calculated as N-nitroso diethanolamine) in the coolant to not more than 10 ppm by weight, preferably not more than 5 ppm, more preferably not more than 2.5 ppm, even more preferably not more than 1 ppm, and especially not more than 0.1 ppm by weight. A preferred analytical method for determining N- nitrosodiethanolamine is described by the Institut fur Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung (Institute for Occupational Safety and Health of the German Social Accident Insurance), IFA-Arbeitsmappe Blatt Nr. 7748 / 2 (IFA working sheet No. 7748 / 2).

[0035] It is an advantage of the present coolants that they exhibit not only low electrical conductivity but also a high inhibition of corrosion, especially corrosion of ferrous- and aluminium-containing alloys, and nonferrous-alloys.

[0036] The tertiary amines (G) preferably have 2 to 9, especially 4 to 8 carbon atoms. The tertiary amines (G), preferably contain 0 to 3 ether oxygen atoms or 0 to 3, preferably 0 to 2 hydroxyl groups, preferably in the form of 2-hydroxyethyl- or 2-hydroxypropyl-substitutents.

[0037] Target electrical conductivity according to ASTM D 1125 at 25 °C of such coolants (as 50% Ready-To-Use, RTU aqueous solution) is preferably between 5-500 pS / cm, preferably between 5-300 pS / cm , preferably between 5-200 pS / cm, preferably between 5-100 pS / cm , preferably between 10-100 pS / cm, preferably between 15-100 pS / cm, preferably between 20-100 pS / cm, preferably between 25-100 pS / cm, preferably between 30-100 pS / cm, preferably between 35-100 pS / cm, more preferably between 40-100 pS / cm, very particularly preferably between 45-100 pS / cm or between 50-100 pS / cm.

[0038] Such low electrical conductivity makes the coolants according to the present invention suitable not only for cooling systems of ICE, but also for cooling systems of NEV. Appropriate application scenarios of automobiles are battery, E-motor, control units and engine if there is one in BEV, HEV, PHEV, REEV and FCEV and so on. In addition, potential application scenarios also include stationary platforms whereas ICE , battery, E-motor and control unit are used.

[0039] Thus, it is one obvious advantage of the coolants according to the present invention that the car manufacturers do not have to stock different coolants for vehicles with combustion engines and battery and E-motor, but can use only one type of coolant for all vehicles. In another word, “one skeleton key to different doors”.

[0040] Indeed, the coolants according to the present invention address the challenges faced by car manufacturers in the design of thermal management systems for HEV / PHEV as well as solve the problems during the construction and retrofitting of coolant refuelling lines, i.e., chemicals compliance, cost pressures and so on. It brings remarkable economic benefits and has far-reaching practical significance and great historical significance.

[0041] The compounds of the coolants according to the invention are described in more details: (A) Antifreezinq agent

[0042] As antifreezing agent (A) according to the present invention one or more compounds selected from the group consisting of 1 ,2-ethylene glycol, 1 ,2-propylene glycol, 1 ,3-propylene glycol, glycerol or dimers, trimers or oligomers thereof or mono- or dialkyl ethers thereof are used.

[0043] Preference is given to 1 ,2-ethylene glycol or 1,2-propylene glycol or dimers, trimers or oligomers thereof or mono- or dialkyl ethers thereof.

[0044] Special preference is given to 1 ,2-ethylene glycol or 1,2-propylene glycol, especially 1 ,2-ethylene glycol.

[0045] Preferably 1,2-propylene glycol and its derivatives is used. Derivatives of 1,2-propylene glycol may be poly- and oligomers as well as mono- or dialkyl ethers of 1 ,2-propylene glycol, its poly- and oligomers.

[0046] More preferably 1 ,2-ethylene glycol and its derivatives is used. Derivatives of 1 ,2-ethylene glycol may be poly- and oligomers as well as mono- or dialkyl ethers of 1 ,2-ethylene glycol, its poly- and oligomers. Examples are diethylene glycol, triethylene glycol, diethylene glycol mono C1-C4 alkyl ether, and triethylene glycol mono C1-C4 alkyl ether, 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.

[0047] Dimers, trimers or oligomers of the alkylene glycols mentioned are di alkylene glycols, tri alkylene glycols, tetra alkylene glycols as well as higher homologues thereof up to a molecular weight of 598 g / mol.

[0048] Preference is given to the monomeric alkylene glycols and their dimers or trimers, more preferred are the monomeric alkylene glycols and their dimers, special preference is given to the monomeric alkylene glycols.

[0049] Mono- or dialkyl ethers of the above-mentioned alkylene glycols and their poly- and oligomers are preferably mono- or di-Ci- to C4-alkyl ethers, more preferably mono-Ci- to C4-alkyl ethers, even more preferably methyl-, ethyl- or n-butyl ethers, especially mono- methyl-, ethyl- or n-butyl ethers.

[0050] In the context of the present text the phrase "Ci- to C4-alkyl" stands for methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and tert-butyl, preferably methyl, ethyl, n-propyl, n-butyl, iso-butyl, and tert-butyl, more preferably methyl, ethyl, and n-butyl. Preferably compounds (A) are selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and mixtures thereof, 1 ,3-propanediol, higher poly alkylene glycols, alkylene glycol ethers, for example 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 either alone or as mixtures thereof.

[0051] Preferably compound (A) is 1 ,2-ethylene glycol or 1 ,2-propylene glycol, especially 1 ,2-ethylene glycol.

[0052] (B) Water

[0053] Water used for the coolants according to the present invention should be ion-free, designating water with a neutral pH-value and comprising essentially no further ions than those hydroxide ions and hydronium ions out of the autoprotolysis of water at the respective temperature.

[0054] The electrical conductivity (throughout this text determined according to ASTM D 1125) at 25 °C of the ion- free water used should preferably not exceed 20 pS / cm, more preferably not more than 15, even more preferably not more than 10, and especially not more than 5 pS / cm.

[0055] The ion-free water used can be pure distilled or twice-distilled water or water which has been deionized, for example by ion exchange, preferably by ion exchange of at least its cations, more preferably by ion exchange of both cations and anions.

[0056] Water from osmosis can also be used in the coolants according to the present invention.

[0057] (C) Azol derivatives

[0058] The coolants according to the present invention comprise at least one azol derivative (C2) different from (C1) (both see below) and may optionally comprise at least one 2-thiothiazole (C1) additionally to azol derivative (C2).

[0059] (CD 2-Thiothiazole The optional at least one 2-thiothiazole (CD of the general formula (I) where the variable R1 is a carboxyalkyl radical of the formula -(CmH2m)-C00X, where m is from 1 to 4 and X is hydrogen, an alkali metal cation, an ammonium cation or a substituted ammonium cation, and the variables R2 and R3 are each, independently of one another, hydrogen or a Ci-C4-alkyl group, where R2 and R3 together with the two ring carbon atoms of the thiazole ring to which they are attached may also form a five- or six-membered saturated or unsaturated ring.

[0060] Preference is given to the benzothiazoles of the general formula (III) where the variable R is hydrogen or a Ci-Cio-alkyl radical, in particular methyl or ethyl, and the variable R' is -S-R1.

[0061] Preferred are (2-benzothiazylthio)acetic acid (R = H, R' = -S-CH2-COOH) or (2-benzothiazylthio) propionic acid (R = H, R' = -S-CH2-CH2-COOH), especially (2-benzothiazylthio)acetic acid.

[0062] (C2) Azol derivative different from (CD

[0063] The coolants according to the invention comprise at least one azol derivative (C2) different from (CD-

[0064] Azole derivatives in the context of the present description mean five-membered heterocyclic compounds having 2 or 3 heteroatoms from the group consisting of nitrogen and sulphur and comprise no or at most one sulphur atom and can bear an aromatic or saturated six-membered fused-on ring.

[0065] These five-membered heterocyclic compounds (azole derivatives) usually contain two N atoms and no S atom, 3 N atoms and no S atom or one N atom and one S atom as heteroatoms.

[0066] Preferred groups of the specified azole derivatives are annellated imidazoles and annellated 1 ,2,3-triazoles of the general formula where the variable R is hydrogen or a Ci-Cio-alkyl radical, in particular methyl or ethyl, and the variable X is a nitrogen atom or the C-H group.

[0067] Typical and preferred examples of azole derivatives of the general formula (1) are benzimidazole (X = C-H, R = H), benzotriazoles (X = N, R = H) and tolutriazole (tolyltriazole) (X = N, R = CH3). A typical example of an azole derivative of the general formula (2) is hydrogenated 1 ,2,3-tolutriazole (tolyltriazole) (X = N, R = CH3).

[0068] A further preferred group of the specified azole derivatives is benzothiazoles of the general formula (3) where the variable R is as defined above and the variable R' is hydrogen, a Ci-Cio-alkyl radical, in particular methyl or ethyl, or in particular a mercapto group (-SH). A typical example of an azole derivative of the general formula (3) is 2-mercaptobenzothiazole. Further suitable azole derivatives are non-annellated azole derivatives of the general formula (4)

[0069] X - \

[0070] F

[0071] H

[0072] (4) where the variables X and Y together are two nitrogen atoms or one nitrogen atom and a C-H group, for example 1 H-1 ,2,4-triazole (X = Y = N) or preferably imidazole (X = N, Y = C-H).

[0073] 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.

[0074] (D) Inorganic salt

[0075] The inorganic salt (D) is optional, however, in a preferred embodiment at least one inorganic salt (D) is present.

[0076] Preferably the inorganic salt (D) is at least one inorganic salt as further corrosion inhibitor selected from the group consisting of molybdates, silicates, borates, vanadates, tungstates, inorganic phosphate salts, and antimonates, preferably selected from the group consisting of molybdates, silicates, borates, inorganic phosphate salts, and vanadates, more preferably selected from the group consisting of molybdates, silicates, borates, inorganic phosphate salts, and vanadates, even more preferably selected from the group consisting of inorganic molybdates, phosphate salts, and silicates, and especially are molybdates.

[0077] Inorganic phosphate salt may be used in the form of the alkali metal, ammonium or substituted ammonium salts of orthophosphoric acid H3PO4 or the acid itself, where alkali metal, ammonium or substituted ammonium salts have the meanings indicated above. However, the component will generally be present entirely or predominantly in salt form in the coolant of the invention which normally has a pH of from 4 to 11 , in particular from 7 to 11 . When free orthophosphoric acid is used, this is usually converted by means of sodium or potassium hydroxide, ammonia or appropriate amines into the desired salts. Further suitable components are alkali metal, ammonium or substituted ammonium salts of diphosphoric acid, of metaphosphoric acids, of pyrophosphoric acids and / or of polyphosphoric acids or the acids themselves, where alkali metal, ammonium or substituted ammonium salts have the meanings indicated above. It is also possible to use mixtures of the salts and / or acids mentioned. Typical representatives of such phosphates are sodium dihydrogenphosphate, disodium hydrogenphosphate, trisodium phosphate, sodium diphosphate, tetrasodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate and the analogous potassium salts.

[0078] As molybdate it is usual to use the alkali metal, ammonium or substituted ammonium salts of molybdic acid H2MOO4 or the acid itself, where alkali metal, ammonium or substituted ammonium salts have the meanings indicated above. Typical representatives of such molybdates (D) are sodium molybdate and potassium molybdate.

[0079] Inorganic silicates are sodium or potassium salts of the group consisting of orthosilicates (SiCU4-), metasilicates (SiOs2), and pyrosilicates (Si2O / 6“).

[0080] Borates are usually used in the form of sodium tetraborate (borax).

[0081] (E) Orqanosilicon Compounds

[0082] The coolants optionally may comprise at least one organosilicon compound selected from the group consisting of

[0083] - esters of orthosilicic acid (E1) and

[0084] - alkoxy alkylsilanes (E2).

[0085] (E1) Esters of orthosilicic acid are compounds of the formula

[0086] Si(OR5)4 wherein

[0087] R5is an organic substituent comprising 1 to 6 carbon atoms, for example a linear or branched, preferably a linear alkyl substituent comprising 1 to 6 carbon atoms or an aromatic substituent comprising 6 carbon atoms, more preferably an alkyl substituent comprising 1 to 4 carbon atoms and even more preferably an alkyl substituent comprising 1 or 2 carbon atoms.

[0088] (E2) Alkoxy alkylsilanes are less preferred and both the alkoxy substituent as well as the alkyl group comprise a linear or branched, preferably a linear alkyl substituent comprising 1 to 6 carbon atoms, more preferably an alkyl substituent comprising 1 to 4 carbon atoms and even more preferably an alkyl substituent comprising 1 or 2 carbon atoms. Typical examples of compounds are tetraalkoxysilanes, preferably tetramethoxysilane and tetraethoxysilane, and alkoxyalkylsilanes, preferably triethoxymethylsilane, diethoxydimethylsilane, ethoxytrimethylsilane, trimethoxymethylsilane, dimethoxydimethylsilane and methoxytrimethylsilane. Preference is given to tetraalkoxysilanes, particularly preferably tetramethoxysilane and tetraethoxysilane, with very particular preference being given to tetraethoxysilane.

[0089] Esters of orthosilicic acid (E1) are preferred over compounds (E2).

[0090] The organosilicon compounds are present in the coolants RTU according to this invention, then in amounts of 0.01 to 2.0 wt%, preferably 0.01 to 1 .0 wt%, more preferably 0.05 to 1 .0 wt%.

[0091] (F) Carboxylic acids

[0092] Carboxylic acids (F) are optional, however, in a preferred embodiment at least one carboxylic acid (F) is present.

[0093] The coolants according to the present invention preferably further comprise at least one aliphatic, cycloaliphatic or aromatic monocarboxylic acid (F1), dicarboxylic or tricarboxylic acid (F2) or in the form of alkali metal, ammonium or substituted ammonium salts thereof having from 3 to 21 carbon atoms in the acid part.

[0094] (F1) aliphatic, cycloaliphatic or aromatic, preferably aliphatic or aromatic, and very preferably aliphatic monocarboxylic acids having in each case from 3 to 16 carbon atoms, or in the form of alkali metal, ammonium or substituted ammonium salts.

[0095] (F2) aliphatic or aromatic dicarboxylic or tricarboxylic acids, preferably dicarboxylic acids, even more preferably aliphatic dicarboxylic acids having in each case from 3 to 21 carbon atoms or in the form of alkali metal, ammonium or substituted ammonium salts.

[0096] Possible linear or branched aliphatic or cycloaliphatic, preferably aliphatic monocarboxylic acids of group (F1) are, for example, propionic acid, pentanoic acid, hexanoic acid, cyclohexylacetic acid, n-octanoic acid, 2-ethyl hexanoic acid, n-nonanoic acid (pelargonic acid), isononanoic acid, decanoic acid, neodecanoic acid, undecanoic acid or dodecanoic acid. Suitable aromatic monocarboxylic acids of group (F1) are in particular benzoic acid and also, for example, Ci-Cs-alkylbenzoic acids such as o-, m- or p-methylbenzoic acid or p-tert-butyl benzoic acid, hydroxyl-comprising aromatic monocarboxylic acids such as o-, m- or p- hydroxybenzoic acid or p-(hydroxymethyl)benzoic acid or halobenzoic acids such as o-, m- or p- fluorobenzoic acid. As used herein, isononanoic acid refers to one or more branched-chain aliphatic carboxylic acids with 9 carbon atoms. Embodiments of isononanoic acid used in the engine coolant composition 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-tetramethylpentanoic acid (e.g., CAS No. 3302-12-3) and combinations thereof. In a preferred embodiment, isononanoic acid has as its main 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 balance of the isononanoic acid may include other nine carbon carboxylic acid isomers and minor amounts of one or more contaminants. In a preferred embodiment, the isononanoic acid has as its main component greater than 90% of 3,5,5-trimethylhexanoic acid and even more preferably, the main component is greater than 95% 3,5,5-trimethylhexanoic acid. Preferred are octanoic acid, n-nonanoic acid (pelargonic acid), and isononanoic acid.

[0097] Typical examples of dicarboxylic or tricarboxylic acids, preferably dicarboxylic acids, more preferably aliphatic dicarboxylic acids of group (F2) are malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid (decanedioic acid), undecanedioic acid, dodecanedioic acid, cyclopentadienedicarboxylic acid, terephthalic acid, phthalic acid and triazinetriiminocarboxylic acids such as 6,6',6"-(1 ,3,5-triazine-2,4,6-triyltriimino)trihexanoic acid. Among these the aliphatic individuals are especially preferred. Preferred are sebacic acid (decanedioic acid) and adipic acid.

[0098] The abovementioned carboxylic acids (F) are usually present entirely or predominantly as alkali metal, ammonium or substituted ammonium salts, as defined above, even when they are to have been added as free acids in the production of the antifreeze concentrate of the invention since the concentrate normally has a pH of from 4 to 11 , in particular from 7 to 11 , more preferably from 7 to 10, even more preferably from 7.5 to 9.5. Components (F) used as free carboxylic acids are usually converted by means of sodium or potassium hydroxide, ammonia or appropriate amines into the desired salts, preferably by means of sodium or potassium hydroxide.

[0099] In one embodiment at least one aliphatic monocarboxylic acid is present in the coolants according to the invention.

[0100] In another embodiment at least one aliphatic dicarboxylic acid is present in the coolants according to the invention. In a preferred embodiment a combination of at least one aliphatic mono- and at least one aliphatic dicarboxylic acid is present in the coolants according to the invention.

[0101] (G) Organic tertiary amine

[0102] The tertiary amines (G) preferably have 2 to 9, especially 4 to 8 carbon atoms. The tertiary amines (G) preferably contain 0 to 3 ether oxygen atoms or 0 to 3, preferably 0 to 2 hydroxyl groups, more preferably 1 or 2 hydroxyl groups, even more preferably 2 hydroxyl groups, especially in the form of 2-hydroxyethyl- or 2-hydroxypropyl-substitutents. Preferred examples are triethanolamine, triisopropanolamine, C1-C10-alkyl diethanolamine, preferably C4-C10-alkyl diethanolamine, C1-C10-alkyl diisopropanolamine, preferably C1- C4-alkyl diisopropanolamine.

[0103] In a preferred embodiment amines (G) comprise at least one 2-hydroxyethyl- or 2-hydroxypropyl-group, more preferably at least one 2-hydroxyethyl-group.

[0104] Preferred amines (G) comprise one, two or three 2-hydroxyethyl- or 2-hydroxypropyl-groups, preferably two or three 2-hydroxyethyl- or 2-hydroxypropyl-groups, very preferably two 2-hydroxyethyl-groups or three 2- hydroxypropyl-groups.

[0105] Preference is given to tertiary amines (G) selected from the group consisting of triethanolamine, triisopropanolamine, C1-C10-alkyl diethanolamine, C1-C10-alkyl diisopropanolamine, preferentially selected from the group consisting of triisopropanolamine, C4-C8-alkyl diethanolamine, C1 -C4-alkyl diisopropanolamine, especially preferentially selected from the group consisting of triisopropanolamine, N- methyl diisopropanolamine, N-butyl diethanolamine and N-octyl diethanolamine.

[0106] Especially preferred are N-methyl diisopropanolamine, n-butyl diethanolamine, and octyl diethanolamine, N-methyl diisopropanolamine and octyl diethanolamine being especially preferred.

[0107] Due to the manufacturing process, tertiary amines often contain a low content of secondary amines, especially when the tertiary amines are obtained through alkylation, alkoxylation, or hydrogenation.

[0108] In a preferred embodiment of the present invention, the content of secondary amines in the tertiary amines (G) used does not exceed 5 wt%, particularly preferably not more than 3 wt%, very particularly preferably not more than 2 wt%, especially not more than 1 wt%, and specifically not more than 0.5 wt%. (H) Primary Amine

[0109] According to the present invention at least one organic compound with at least one primary amino group is present in the coolants. Such organic compounds may comprise one, two, three or even more amino groups, preferably one to three, more preferably one or two, and even more preferably exactly one primary amino group.

[0110] It is even possible to use organic amines as primary amines (H) which comprise secondary amino groups, as long as the number of primary amino groups in such a compound (H) exceeds the number of secondary amino groups.

[0111] In case the compound (H) comprises primary as well as secondary amino groups, for example when the primary amines are obtained through alkylation, alkoxylation, or hydrogenation, the molar content of compounds bearing a secondary amino group is not more than 20 mol% with regard to the content of compounds bearing a primary amino group, preferably not more than 15, more preferably not more than 10, and especially not more than 5 mol%.

[0112] However, in a preferred embodiment the compound (H) does not contain any secondary amino groups, but only primary and tertiary amino groups, even more preferably compound (H) comprises only primary amino groups, and especially exactly one primary amino groups without any further secondary or tertiary amino groups.

[0113] Compound (H) may comprise one or more compounds, for example one to three, preferably one or two, and especially exactly one compound (H).

[0114] Prerequisites for compounds (H) besides the presence of at least one primary amino group is a sufficient solubility in the coolant and a sufficiently nucleophilic primary amino group to suppress formation of nitrosami nes.

[0115] One example for a class for compounds (H) are alkylene diamines, such as 1 ,3-propane diamine, ethylene diamine, its oligomers and polymers. Examples are 1 ,3-propane diamine, ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentaamine, pentaethylene hexamine, and polyethylene imines. Examples of monomeric alkylene diamines are ethylene diamine, 1 ,3-propane diamine, 1 ,4-butane diamine, 1 ,6-hexane diamine, 1 ,8-octane diamine, and 1 ,12-dodecane diamine, preferably ethylene diamine, 1,3- propane diamine, and 1,6-hexane diamine.

[0116] Under a polyethyleneimine a compound is understood which contains the substructure >N-CH2-CH2-N< as a repeating unit one or more times.

[0117] Preferred polyethyleneimines are those selected from the group consisting of formula (I) wherein x and y are independently 0 (zero) or a positive integer, with the proviso that

[0118] - in formula (II), the sum of x and y is not 0 (zero).

[0119] For each x, the substituent at the nitrogen atom -CH2-CH2-[-NH-CH2-CH2-]y-NH2 can have a different value for y. Preferred is x at least 1 , particularly preferred at least 2, very particularly preferred at least 3, especially at least 5, and specifically at least 10.

[0120] Preferred is y at least 1 , particularly preferred at least 2, very particularly preferred at least 3, especially at least 5, and specifically at least 10.

[0121] The upper limit for x and y can independently be up to 1500, preferably up to 1400, particularly preferably up to 1300, very particularly preferably up to 1200, especially up to 1000, and specifically up to 750.

[0122] The ratio of primary to secondary to tertiary nitrogen atoms in the polyethyleneimines, as determined by 13C-NMR spectroscopy, is preferably 1 : 0.5 to less than 1 : 0.3 to 0.9, preferably 1 : 0.4 to 0.9 : 0.4 to 0.8, more preferably 1 : 0.5 to 0.8 : 0.4 to 0.8, and in particular 1 : 0.6 to 0.8 : 0.5 to 0.8.

[0123] Suitable methods for producing polyethyleneimines by polymerization of ethyleneimine (aziridine) are known to those skilled in the art.

[0124] Polyethyleneimine is preferably produced by cationic ring-opening polymerization of ethyleneimin in the presence of Bronsted acids, Lewis acids, halogenalkanes, or carbon dioxide. Examples can be found in US 2,182,306 and US 3,203,910, as well as US 2001 / 0039318.

[0125] As another reference with further examples of polyethylene synthesis, reference is made to "Aziridines and azetidines: building blocks for polyamines by anionic and cationic ring-opening polymerization" by Gleede, T.; Reisman, L.; Rieger, E.; Mbarushimana, P. C.; Ru-par, P.A.; Wurm, F. R.; Polymer Chemistry 2019, 10, 3257.

[0126] The obtained polyethyleneimines are generally branched or hyperbranched polyethyleneimines.

[0127] In this way, polyethyleneimines are obtainable with a weight average molecular weight Mw in the range of 500 to 2,000,000 g / mol, preferably in the range of 500 to 100,000 g / mol.

[0128] As polymers, they exhibit a molecular weight distribution. The values for the indices x in formula (I) or the sum (x + y) in formula (II) are chosen so that polyethyleneimines of these molecular weights are achieved, preferably from 11 to 930, particularly preferably from 17 to 700, and very particularly preferably from 23 to 350. Out of this class of compounds the monomeric alkylene diamines are preferred.

[0129] Due to the presence of secondary amino groups in the oligomers of ethylene diamine and in the polyethylene imines, these classes of amines are less preferred as compounds (H).

[0130] Another example for a class of compounds (H) are mono alkanolamines, e.g. monoethanolamine, mono- 1 ,2-propanolamine, and mono-1 , 3-propanolamine.

[0131] As pointed out above due to the manufacturing processes of these compounds they also may comprise small amounts of secondary amino groups. Therefore, if these compounds are used, the content of secondary amino groups should not exceed 20 mol%, preferably not more than 15, more preferably not more than 10, and especially not more than 5 mol%.

[0132] Due to the presence of secondary amino groups in the alkanolamines, this class of amines is especially less preferred as compounds (H).

[0133] It is also possible to combine an azol substructure with a primary amino group e.g. in 2-aminothiazole or amino benzothiazoles of the general formula (5) where the variable R is hydrogen or a Ci-Cio-alkyl radical, in particular methyl or ethyl.

[0134] Preferred examples are 2-aminothiazole and 2-aminobenzothiazole.

[0135] An especially preferred compound (H) is at least one alkoxy aminoalkylsilane.

[0136] One preferred type of Alkoxy Aminoalkylsilanes are the compounds of the formula

[0137] H2N-(CH2)n-SiY3 wherein n is an integer of 1-3, preferably 2 or 3, and especially 3, and

[0138] Y is an (C1-C4-) alkoxy functional group attached to silicon, including but not limited to methoxy groups, ethoxy groups, n-butoxy groups, preferably methoxy groups or ethoxy groups.

[0139] Typical examples are 3-Ami nopropyltrimethoxysilane (e.g., CAS No. 13822-56-5) and 3-

[0140] Ami nopropyltriethoxysilane (e.g., CAS No. 919-30-2).

[0141] Another type of Alkoxy Aminoalkylsilanes are the compounds of the formula

[0142] H2N-(CH2) n-SiYmZ3-m wherein

[0143] Y, and n are defined as above, m is an integer of 1-3, preferably 1 or 2, and very preferably 1 , Z is (Ci-C4-)alkyl, including but not limited to methyl, ethyl, n-butyl, preferably methyl or ethyl, very preferably methyl.

[0144] Typical examples are 3-(Dimethoxymethylsilyl)propylamine (e.g. CAS No. 3663-44-3) and 3- Aminopropylmethyldiethoxysilane (e.g. CAS No. 3179-76-8).

[0145] The primary amine compounds (H) are present in the coolants according to this invention in amounts of 0.01 to 2.0 wt%, preferably 0.01 to 1 .0 wt%, more preferably 0.05 to 1 .0 wt%.

[0146] (J) Other additives

[0147] It is possible to add further typical coolant additives to the coolants of the present invention.

[0148] As further customary additives, the inventive coolant may also comprise, in customary small amounts, defoamers (generally in amounts of from 0.001 to 0.01 % by weight) and, for reasons of hygiene and safety in the event that it is swallowed, and bitter substances (for example of the denatonium benzoate type, generally in amounts of from 0.005 to 0.02% by weight).

[0149] Furthermore, the coolants may comprise dyes (generally in amounts of from 0.001 to 0.005% by weight) and hard water stabilisers (generally in amounts of from 0.1 to 0.5% by weight), e.g. based on polyacrylic acid, polymaleic acid, acrylic acid-maleic acid copolymers, polyvinylpyrrolidone, polyvinylimidazole, vinylpyrrolidone-vi nylimidazole copolymers and / or copolymers of unsaturated carboxylic acids and olefins.

[0150] Composition

[0151] The composition of the coolants (Ready to use, “RTU”) according to present invention are as follows:

[0152] (A) 45 to 65 wt% of at least one antifreezing agent, preferably 50 to 60, more preferably 50 to 55 wt%

[0153] (B) 30 to 50 wt% water, preferably 35 to 50, more preferably 40 to 50 wt%,

[0154] (C1) 0 to 0.5 wt% of at least one 2-thiothiazole of the general formula (I), preferably 0.02 to 0.4, more preferably 0.05 to 0.2 wt%, and / or

[0155] (C2) 0.01 to 0.75 wt% of at least one azol derivative different from (C1), preferably 0.02 to 0.5, more preferably 0.05 to 0.25 wt%,

[0156] (D) 0 to 0.75 wt% of at least one inorganic salt as further corrosion inhibitor, preferably 0.001 to 0.75, more preferably 0.001 to 0.5, even more preferably 0.001 to 0.3 wt%,

[0157] (E) 0 to 2 wt% at least one organosilicon compound, preferably 0.01 to 2 wt%, more preferably 0.05 to

[0158] 1 .5wt%, even more preferably 0.05 to 1 .0 wt%,

[0159] (F) 0 to 2 wt% at least one aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acid, preferably 0.001 to 2 wt%, more preferably 0.005 to 1 .0 wt%, even more preferably 0.005 to 0.5 wt%, and

[0160] (G) 0.01 to 2.0 wt% of at least one organic tertiary amine, preferably 0.02 to 1 .75wt%, more preferably 0.02 to 1.0 wt%, more preferably 0.02 to 0.5 wt%,

[0161] (H) 0.01 to 2.0 wt% of at least one organic compound with at least one primary amino group, preferably 0.02 to 1.75wt%, more preferably 0.02 to 1.0 wt%, more preferably 0.02 to 0.5 wt%,

[0162] (J) optionally other additives selected from the group consisting of defoamers, bitter substances and hard water stabilisers, with the proviso that the sum of all components always add up to 100 wt%, and with the proviso that at least one of compounds (C2) and / or (C1) is present.

[0163] The coolants RTU as described are usually destined for use at the end user, i.e. for refilling of the cooling system of vehicles.

[0164] Coolants usually are obtained from coolant concentrates by dilution with water (B). Therefore, another subject matter of the present invention are coolant concentrates which usually contain little or no water (B): The composition of the coolant concentrates according to present invention are as follows:

[0165] (A) 80 to 95 wt% of at least one antifreezing agent, preferably 80 to 90wt%, more preferably 85 to 95 wt%

[0166] (B) 0 to 10 wt% water, preferably 0 to 8, more preferably 0 to 5 wt%,

[0167] (C1 ) 0 to 1 .0 wt% of at least one 2-thiothiazole of the general formula (I), preferably 0.04 to 0.8 wt%, more preferably 0.1 to 0.4 wt%, and / or

[0168] (C2) 0.02 to 1 .5 wt% of at least one azol derivative different from (C1), preferably 0.04 to 1 .0 wt%, more preferably 0.1 to 0.5 wt%,

[0169] (D) 0 to 1 .5 wt% of at least one inorganic salt as further corrosion inhibitor, preferably 0.002 to 1 .5 wt%, more preferably 0.002 to 1 .0 wt%, even more preferably 0.002 to 0.6 wt%,

[0170] (E) 0 to 4.0 wt% at least one organosilicon compound, preferably 0.1 to 4.0 wt%, more preferably 0.1 to 3.0 wt%, even more preferably 0.1 to 2.0 wt%,

[0171] (F) 0 to 4.0 wt% at least one aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acid, preferably 0.01 to 4.0 wt%,more preferably 0.01 to 3.0wt% , even more preferably 0.01 to 2.0 wt%, and

[0172] (G) 0.02 to 4.0 wt% of at least one organic tertiary amine, preferably 0.02 to 2.0%, more preferably 0.02 to 1.0 wt%,

[0173] (H) 0.02 to 4.0 wt% of at least one organic compound with at least one primary amino group, preferably 0.02 to 2.0%, more preferably 0.02 to 1 .0 wt%, with the proviso that the sum of all components always add up to 100 wt%, and with the proviso that at least one of compounds (C2) and / or (C1) is present.

[0174] Coolants are usually obtained from the concentrates by dilution with water (B) in the ratio 1 : 0.75 to 1 :1 .5 (v / v).

[0175] A further embodiment of the present invention are coolant super concentrates. Coolant concentrates usually are obtained from coolant super concentrates by dilution with the glycol (A), respectively coolants may be obtained from coolant super concentrates by dilution with the glycol (A) and water (B). Hence, the coolant super concentrates usually contain little or no water (B) and less glycol than the concentrates. In the concentrates or super concentrates glycol (A) acts as a solvent for the other constituents and, therefore, may be present in higher amounts.

[0176] The composition of the coolant super concentrates according to present invention are as follows: (A) 20 to 90 wt% of at least one antifreezing agent, preferably 30 to 85, more preferably 40 to 80 wt% (B) 0 to 10 wt% water, preferably 0 to 8, more preferably 0 to 5 wt%,

[0177] (C1) O to 1.5 wt% of at least one 2-thiothiazole of the general formula (I), preferably 0.06 to 1.4, more preferably 0.15 to 0.6 wt%, and / or

[0178] (C2) 0.03 to 2.25 wt% of at least one azol derivative different from (C1 ), preferably 0.06 to 1 .5, more preferably 0.15 to 0.75 wt%,

[0179] (D) 0 to 2.25 wt% of at least one inorganic salt as further corrosion inhibitor, preferably 0.01 to 2.25 wt%, more preferably 0.01 to 1 .5 wt%, even more preferably 0.01 to 0.9 wt%,

[0180] (E) 0 to 6.0 wt% at least one organosilicon compound, preferably 0.5 to 6.0 wt%, more preferably 0.5 to 5.0wt%, even more preferably 0.6 to 5.0 wt%,

[0181] (F) 0 to 6 wt% at least one aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acid, preferably 0.05 to 6 wt%, more preferably 0.05 to 4.0 wt%, even more preferably 0.05 to 3.0 wt%, and

[0182] (G) 0.1 to 6.0 wt% of at least on organic tertiary amine, preferably 0.1 to 4.0wt%, more preferably 0.1 to 3.0 wt%, more preferably 0.1 to 2.0 wt%,

[0183] (H) 0.1 to 6.0 wt% of at least one organic compound with at least one primary amino group, more preferably 0.1 to 3.0 wt%, more preferably 0.1 to 2.0 wt%, with the proviso that the sum of all components always add up to 100 wt%, and with the proviso that at least one of compounds (C2) and / or (C1) is present.

[0184] It is an advantage of the present coolants and coolant compositions that they exhibit not only low electrical conductivity but also a high inhibition of corrosion, especially corrosion of ferrous- and aluminium- containing alloys, and non-ferrous-alloys and successfully suppress the formation of nitrosamines to a large extent.

[0185] In addition, present coolants and coolant compositions according to the invention have high tolerance to residues of fluoroaluminate fluxes in soldered aluminium radiators and cooling plates, i.e. good compatibility with flux. In other words, the Si-containing coolant shows no Si-depletion in the presence of flux.

[0186] For some time, the cooling apparatus or cooling circuits for ICE and NEV which are usually used in vehicle and automobile construction but also for stationary engines have been made predominantly or solely of aluminium or aluminium alloys. Specific soldering processes, for example soldering under a protective gas atmosphere, are used here. In such soldering processes, the concomitant use of a flux is necessary. Here, potassium fluoroaluminates are usually used as flux, for example a mixture of KAIF4, K2AIF5 and K3AIF6 (for example commercially available under the name Nocolok®). Part of the fluxes mentioned remains on the surface of the cooling apparatus after the soldering operation. These flux residues in the cooling apparatus lead more or less quickly to precipitation of aluminium hydroxide gels and thus to sludge formation in the cooling circuit after introduction of aqueous coolant compositions and operation of the engine due to a chain of chemical reactions, which are in equilibrium with one another, with the water and the constituents of the aqueous coolant compositions. This greatly restricts the effectiveness of heat removal from the (electric) engine and as a consequence also the functions of the heat exchange for the heating system, cooling of the air supply and gearbox oil cooling. In addition, the presence of aluminium hydroxide gels has an adverse effect on the corrosion protection provided by the coolant because the corrosion protection action is considerably reduced as a result of adsorption of the corrosion inhibitors on the aluminium hydroxide gels.

[0187] As a matter of fact, the adoption of flux in NEV is even more widespread and significant compared to ICE due to the large scale application of cooling plates for battery thermal management. These cooling plates are normally made of Aluminium alloys, placed outside and / or inside of battery pack in which coolant flow through the channels to remove the heat generated by battery pack. More specifically, the cooling plates are made by soldering process under a protective gas atmosphere in which flux is indispensable.

[0188] There is a demand for coolant compositions which have a high tolerance to residues of fluoroaluminate fluxes in soldered aluminium radiators and cooling plates, i.e. which no longer tends, or tends to a significantly less extent, to form precipitates of aluminium hydroxide gels and formation of sludge in the cooling circuit and thus makes more effective corrosion protection possible.

[0189] Therefore, it is even more advantageous that present coolants and coolant compositions further have high tolerance to residues of fluoroaluminate fluxes in soldered aluminium radiators and cooling plates, i.e. good compatibility with flux.

[0190] Therefore, another aspect of the present invention is the use of the coolants according to the present invention in cooling systems with ICE, battery, E-motors, control unit for automobiles and stationary platforms as well. The cooling systems are at least partly, preferably predominantly or solely made of aluminium or aluminium alloys.

[0191] The electrical conductivity is reduced compared to the coolants according to EP 2956520 B1 with simultaneous retention of their anti-corrosion activity.

[0192] The coolants according to the present invention particularly demonstrate their advantage in cooling systems which contain at least one metallic component that has previously come into contact with nitrites, for example in the form of metal working fluids. Nitrites are introduced into the cooling system through such metallic components and thus come into contact with secondary amines, which are mostly present in small quantities in tertiary amines contained in the coolants, and can thus form nitrosamines.

[0193] Therefore, another aspect of the present invention are cooling systems comprising at least one metal component which was previously in contact with nitrites, and further comprising a coolant composition, comprising

[0194] (A) at least one antifreezing agent selected from the group consisting of 1 ,2-ethylene glycol, 1 ,2-propylene glycol, 1 ,3-propylene glycol, glycerol, dimers, trimers or oligomers thereof, and mono- or dialkyl ethers thereof

[0195] (B) water

[0196] (C2) at least one azol derivative different from (C1),

[0197] (C1) optionally additionally to azol derivative (C2) at least one 2-thiothiazole of the general formula (I) where the variable R1 is a carboxyalkyl radical of the formula -(CmH2m)-C00X, where m is from 1 to 4 and X is hydrogen, an alkali metal cation, an ammonium cation or a substituted ammonium cation, and the variables R2 and R3 are each, independently of one another, hydrogen or a Ci-C4-alkyl group, where R2 and R3 together with the two ring carbon atoms of the thiazole ring to which they are attached may also form a five- or six-membered saturated or unsaturated ring,

[0198] (D) optionally at least one inorganic salt as further corrosion inhibitor selected from the group consisting of molybdates, borates, silicates, vanadates, tungstates, and antimonates,

[0199] (E) optionally at least one organosilicon compound selected from the group consisting of

[0200] - esters of orthosilicic acid (E1) and

[0201] - alkoxy alkylsilanes (E2),

[0202] (F) optionally at least one aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acid as acid or in the form of alkali metal, ammonium or substituted ammonium salts thereof having from 3 to 21 carbon atoms in the acid part, preferably at least one monocarboxylic acid combined with one dicarboxylic acid, and (G) at least one organic tertiary amine, and

[0203] (H) at least one organic compound with at least one primary amino group.

[0204] With the help of the coolants according to the present invention the formation of nitrosamines can successfully be suppressed so that e.g. workshop personnel who may come in contact with such coolants is protected from health damage.

[0205] The invention is illustrated by the following examples without being restricted to such examples.

[0206] Examples

[0207] If not mentioned otherwise electrical conductivity was determined according to ASTM D 1125 at 25 °C in pS / cm throughout the text.

[0208] 250 ml of each of the two concentrates listed in the table were diluted to a 50 % aqueous solution (approx. 500 mL total fluid volume), 0.5 g sodium nitrite was added, the mixture heated to 135 °C for 3 hours at a pressure of 1.9 bar, and the reaction mixture cooled to room temperature.

[0209] Sodium nitrite was used in an approx. 10OOfold excess to the secondary amine.

[0210] The content of nitrosamines was analysed by gas chromatography (GC), the average of two samples was calculated, and the result given as N-nitroso diethanolamine.

[0211] Concentrates:

[0212] The content of nitrosamines (given as N-nitroso diethanolamine) for the 50% aqueous coolant from concentrate 1 was determined to be 0.08 ppm according to the invention, while the comparative coolant from concentrate 2 yielded 40 ppm.

[0213] The blank value of 50% aqueous coolant from both concentrates 1 as well as 2 without the presence of sodium nitrite yielded a content of nitrosamines below the detection level of 0.05 ppm.

Claims

CLAIMS1 . Use of coolants, comprising(A) at least one antifreezing agent selected from the group consisting of 1 ,2-ethylene glycol, 1,2- propylene glycol, 1 ,3-propylene glycol, glycerol, dimers, trimers or oligomers thereof, and mono- or dialkyl ethers thereof(B) water(C2) at least one azol derivative different from (C1),(C1) optionally additionally to azol derivative (C2) at least one 2-thiothiazole of the general formula(I)where the variable R1 is a carboxyalkyl radical of the formula -(CmH2m)-C00X, where m is from 1 to 4 and X is hydrogen, an alkali metal cation, an ammonium cation or a substituted ammonium cation, and the variables R2 and R3 are each, independently of one another, hydrogen or a C1-C4- alkyl group, where R2 and R3 together with the two ring carbon atoms of the thiazole ring to which they are attached may also form a five- or six-membered saturated or unsaturated ring,(D) optionally at least one inorganic salt as further corrosion inhibitor selected from the group consisting of molybdates, borates, silicates, vanadates, tungstates, and antimonates,(E) at least one organosilicon compound comprising at least one alkoxy aminoalkylsilane (E3) and optionally additionally at least one further organosilicon compound selected from the group consisting of- esters of orthosilicic acid (E1) and- alkoxy alkylsilanes (E2),(F) optionally at least one aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acid as acid or in the form of alkali metal, ammonium or substituted ammonium salts thereof having from 3 to 21 carbon atoms in the acid part, preferably at least one monocarboxylic acid combined with one dicarboxylic acid, and(G) at least one organic tertiary amine, and(H) at least one organic compound with at least one primary amino groupin cooling systems comprising at least one metal component which was previously in contact with nitrites.

2. Cooling systems comprising at least one metal component which was previously in contact with nitrites, and further comprising a coolant composition, comprising(A) at least one antifreezing agent selected from the group consisting of 1 ,2-ethylene glycol, 1,2- propylene glycol, 1 ,3-propylene glycol, glycerol, dimers, trimers or oligomers thereof, and mono- or dialkyl ethers thereof(B) water(C2) at least one azol derivative different from (C1),(C1) optionally additionally to azol derivative (C2) at least one 2-thiothiazole of the general formula(I)where the variable R1 is a carboxyalkyl radical of the formula -(CmH2m)-C00X, where m is from 1 to 4 and X is hydrogen, an alkali metal cation, an ammonium cation or a substituted ammonium cation, and the variables R2 and R3 are each, independently of one another, hydrogen or a C1-C4- alkyl group, where R2 and R3 together with the two ring carbon atoms of the thiazole ring to which they are attached may also form a five- or six-membered saturated or unsaturated ring,(D) optionally at least one inorganic salt as further corrosion inhibitor selected from the group consisting of molybdates, borates, silicates, vanadates, tungstates, and antimonates,(E) optionally at least one organosilicon compound selected from the group consisting of- esters of orthosilicic acid (E1) and- alkoxy alkylsilanes (E2),(F) optionally at least one aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acid as acid or in the form of alkali metal, ammonium or substituted ammonium salts thereof having from 3 to 21 carbon atoms in the acid part, preferably at least one monocarboxylic acid combined with one dicarboxylic acid, and(G) at least one organic tertiary amine, and(H) at least one organic compound with at least one primary amino group.

3. Use according to Claim 1 and cooling systems according to Claim 2, wherein the coolant comprises(A) 45 to 65 wt% of at least one antifreezing agent,(B) 30 to 50 wt% water,(C1) 0.0 to 0.5 wt% of at least one 2-thiothiazole of the general formula (I), (C2) 0.01 to 0.75 wt% of at least one azol derivative different from (C1),(D) 0 to 0.75 wt% of at least one inorganic salt as further corrosion inhibitor,(E) 0 to 2 wt% at least one organosilicon compound,(F) 0 to 2 wt% at least one aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acid, and(G) 0.01 to 2.0 wt% of at least one organic tertiary amine;(H) of 0.01 to 2.0 wt% of at least one organic primary amine;(J) optionally other additives selected from the group consisting of defoamers, bitter substances and hard water stabilisers, with the proviso that the sum of all components always add up to 100 wt%.

4. Use and coolants systems according to any one of the preceding claims, wherein the electrical conductivity according to ASTM D 1125 at 25 °C of the coolant as 50% RTU aqueous solution is from 5 to 500 pS / cm.

5. Use and coolants systems according to any one of the preceding claims, wherein the antifreezing agent (A) is selected from the group consisting of 1 ,2-ethylene glycol and 1 ,2-propylene glycol, preferably 1 ,2-ethylene glycol.

6. Use and coolants systems according to any one of the preceding claims, wherein the 2-thiothiazole of the general formula (I) (C1) is present and selected from the group consisting of (2-benzo- thiazylthio)acetic acid and 3-(2-benzothiazylthio)propionic acid or an alkali metal, ammonium or substituted ammonium salt thereof.

7. Use and coolants systems according to any one of the preceding claims, wherein at least one azol derivative (C2) different from (C1) is present and is selected from the group consisting of benzotriazole, tolutriazole (tolyltriazole), and hydrogenated tolutriazole, preferably selected fromthe group consisting of benzotriazole and tolutriazole.

8. Use and coolants systems according to any one of the preceding claims, wherein the at least one inorganic salt (D) is present and selected from the group consisting of molybdates, silicates, borates, vanadates, and tungstates, preferably selected from the group consisting of molybdates, silicates, borates, and vanadates, more preferably selected from the group consisting of molybdates, silicates, borates, and vanadates, even more preferably selected from the group consisting of molybdates, and silicates, and especially are molybdates.

9. Use and coolants systems according to any one of the preceding claims, wherein the at least one carboxylic acid is present and comprises at least one aliphatic monocarboxylic acid, preferably selected from the group consisting of 2-ethylhexanoic acid, n-octanoic acid, n-nonanoic acid (pelargonic acid), and isononanoic acid.

10. Use and coolants systems according to any one of the preceding claims, wherein the at least one carboxylic acid is present and comprises at least one aliphatic dicarboxylic acid, preferably selected from the group consisting of adipic acid and sebacic acid / decanedioic acid.11 . Use and coolants systems according to any one of the preceding claims, wherein a combination of at least one aliphatic monocarboxylic acid and at least one aliphatic dicarboxylic acid is present.

12. Use and coolants systems according to any one of the preceding claims, wherein organic tertiary amine (G) is selected from the group consisting of triethanolamine, triisopropanolamine, C1-C10- alkyl diethanolamine, C1 -C10-alkyl diisopropanolamine, preferentially selected from the group consisting of triisopropanolamine, C4-C8-alkyl diethanolamine, C1-C4-alkyl diisopropanolamine, especially preferentially selected from the group consisting of triisopropanolamine, N-methyl diisopropanolamine, N-butyl diethanolamine and N-octyl diethanolamine.

13. Use and coolant systems according to Claim 12, wherein the content of secondary amines in the tertiary amines (G) does not exceed 5 wt%, particularly preferably not more than 3 wt%, very particularly preferably not more than 2 wt%, especially not more than 1 wt%, and specifically not more than 0.5 wt%.

14. Use and coolants systems according to any one of the preceding claims, wherein the primary amine(H) is selected from the group consisting of- alkylene diamines,- mono alkanolamines,- 2-aminothiazole or 2-aminobenzothiazole,- Alkoxy Aminoalkylsilanes of the formulaH2N-(CH2)n-SiY3 wherein n is an integer of 1-3, preferably 2 or 3, and especially 3, andY is an (C1-C4-) alkoxy functional group attached to silicon, including but not limited to methoxy groups, ethoxy groups, n-butoxy groups, preferably methoxy groups or ethoxy groups, and- Alkoxy Aminoalkylsilanes of the formulaH2N-(CH2) n-SiYmZ3-m whereinY, and n are defined as above, m is an integer of 1-3, preferably 1 or 2, and very preferably 1 , Z is (Ci-C4-)alkyl, including but not limited to methyl, ethyl, n-butyl, preferably methyl or ethyl, very preferably methyl.

15. Use and coolants systems according to Claim 14, wherein the molar content of compounds bearing a secondary amino group in compound (H) is not more than 20 mol% with regard to the content of compounds bearing a primary amino group, preferably not more than 15, more preferably not more than 10, and especially not more than 5 mol%.

16. Cooling systems according to any one of Claims 2 to 14, wherein the cooling system is at least partly, preferably predominantly or solely made of aluminium or aluminium alloys.

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