New coolant compositions

Abstract

The present invention relates to new coolant compositions for cooling systems, the compositions containing at least one polymer that contains at least one polyethylene imine.

Description

[0001] New coolant compositions

[0002] Description

[0003] The present invention describes novel coolant compositions for cooling systems containing at least one polymer which contains at least one polyethyleneimine.

[0004] The coolants according to the present invention can be used in cooling systems of stationary engines or vehicles with internal combustion engines, electric motors, fuel cells or hybrid engines with a combination of internal combustion engines with electric motors or a combination of internal combustion engines with fuel cells or in generators, such as wind turbines.

[0005] The freezing point-depressing glycol component is usually monoethylene glycol and / or monopropylene glycol, predominantly monoethylene glycol.

[0006] In addition, coolants usually contain at least one inhibitor, usually a mixture of inhibitors, which protects the metals typically used in cooling systems against corrosion. Typical metals include ferrous materials, aluminum and its alloys, copper, and brass. The inhibitors used in coolants usually inhibit corrosion for one or more of these materials, but not for all. For this reason, several inhibitors are usually used to protect the typical materials against corrosion.

[0007] Low molecular weight amines, such as alkylamines or ethanolamines, such as triethanolamine, butyldiethanolamine or octyldiethanolamine, are often used as corrosion inhibitors, especially for iron-containing materials.

[0008] These amines exhibit a comparatively high basicity and, consequently, a high degree of dissociation, which increases the electrical conductivity of the coolant. However, low electrical conductivity is particularly desirable for electric vehicles to prevent a short circuit in the event of a coolant leak and contact with the battery.

[0009] A fundamental challenge in the development of coolants with low electrical conductivity is the fact that most corrosion inhibitors used are ionic in nature. Conventional coolants exhibit electrical conductivities of several thousand pS / cm. Typical corrosion inhibitors are inorganic salts such as nitrites, nitrates, silicates, phosphates, and others, which contribute significantly to electrical conductivity. Organic corrosion inhibitors are carboxylic acids, which exist as carboxylates in the typical pH environment of a coolant and thus also contribute to high electrical conductivity.

[0010] US 2018 / 0100239 A1 describes the corrosion inhibition of metal surfaces by treatment with aqueous solutions of polyethyleneimines.

[0011] Since poly(meth)acrylic acids are often used as corrosion inhibitors for metal surfaces, but form acid-base salts with polyethyleneimines, the simultaneous use of poly(meth)acrylic acids and polyethyleneimines is prohibited and is therefore preferably excluded according to US 2018 / 0100239 A1.

[0012] One object of the present invention was to replace low-molecular-weight amines in coolants with other compounds that exhibit at least as good corrosion inhibition but exhibit lower electrical conductivity in coolants than these low-molecular-weight amines. A further object of the present invention was to identify non-ionic corrosion inhibitors for typical cooling circuit materials, particularly aluminum, that exhibit good corrosion protection while simultaneously exhibiting low electrical conductivity.

[0013] The problem was solved by coolant containing

[0014] - at least 40% water by weight (A)

[0015] - at least 30% by weight of alkylene glycol, alkylene glycol monoalkyl ether and glycerol (B),

[0016] - 0.1 to 5 wt% of at least one acid selected from the group consisting of

[0017] - - (C2a) Benzoic acid as aromatic monocarboxylic acid,

[0018] - - (C2b) at least one aliphatic monocarboxylic acid and

[0019] - - (C3) at least one organic dicarboxylic acid having 4 to 20 carbon atoms,

[0020] - at least 0.01 to 5 wt% of at least one polyethyleneimine (F).

[0021] It was surprising that the simultaneous use of carboxylic acid and polyethyleneimine (F) led to a corrosion-inhibiting effect while maintaining acceptable electrical conductivities.

[0022] Polyethylenimine (F) A polyethyleneimine (F) is understood to be a compound which contains the substructure >N-CH2-CH2-N< one or more times as a repeating unit.

[0023] Polyethylenimines are preferably those selected from the group consisting of the formula (I) where x and y independently represent 0 (zero) or a positive integer, with the proviso that

[0024] - in formula (II) the sum of x and y is not 0 (zero).

[0025] For each x, the substituent on the nitrogen atom can be -CH2-CH2-[-NH-CH2-CH2-] y -NH2 have a different value for y. Preferably, x is at least 1, more preferably at least 2, most preferably at least 3, in particular at least 5, and especially at least 10.

[0026] Preferably, y is at least 1, more preferably at least 2, most preferably at least 3, in particular at least 5 and especially at least 10.

[0027] The upper limit for x and y can be independently up to 1500, preferably up to 1400, particularly preferably up to 1300, most particularly preferably up to 1200, in particular up to 1000 and especially up to 750.

[0028] The 13 The ratio of primary to secondary to tertiary nitrogen atoms in the polyethyleneimines, as determined by C-NMR spectroscopy, is preferably 1:0.5 to 1.5:0.3 to 0.9, preferably 1:0.6 to 1.3:0.4 to 0.8, more preferably 1:0.7 to 1.3:0.4 to 0.8 and in particular 1:0.9 to 1.1:0.5 to 0.8.

[0029] Suitable processes for the preparation of polyethyleneimines by polymerization of ethyl enimine (aziridine) are known to the person skilled in the art.

[0030] Polyethylenimine is preferably prepared by cationic ring-opening polymerization of ethylenimine in the presence of Broensted acids, Lewis acids, haloalkanes, or carbon dioxide. Examples can be found in US 2,182,306 and US 3,203,910, as well as US 2001 / 0039318.

[0031] For further examples of polyethylene synthesis, see "Aziridines and azetidines: building blocks for polyamines by anionic and cationic ring-opening polymerization" Gleede, T.; Reisman, L.; Rieger, E.; Mbarushimana, PC; Ru-par, PA; Wurm, FR; Polymer Chemistry 2019, 10, 3257.

[0032] The polymerization can, for example, be carried out in a batch process in which water and 1,2-dichloroethane as catalyst are added to a reaction vessel, the mixture is heated to a temperature of 70 to 100°C and ethyleneimine is continuously added to the reaction mixture while stirring.

[0033] The resulting polyethyleneimines are generally branched or hyperbranched polyethyleneimines. Polyethylenimines obtainable in this way have 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.

[0034] As polymers, they exhibit a molecular weight distribution. In the context of the present specification, preference is given to using polyethyleneimines whose weight-average molar masses (Mw measured by GPC) of the polyethyleneimines (F) are less than 55,000 g / mol, preferably less than 40,000, more preferably less than 30,000, and even more preferably less than 15,000 g / mol. In a preferred embodiment, the weight-average molar mass Mw is at least 500, preferably at least 750, and very particularly preferably at least 1000 g / mol. The values ​​for the serial numbers x in formula (I) or the sum (x + y) in formula (II) are chosen such that polyethyleneimines of these molar masses are achieved, i.e., preferably from 11 to 930, more preferably from 17 to 700, and very particularly preferably from 23 to 350.The idealized formulas (I) and (II) illustrate the structure of branched polyethyleneimines in which the ratio of primary to secondary to tertiary nitrogen atoms is on average about 1:2:1. Preferred polyethyleneimines have the above-mentioned preferred ratio of primary to secondary to tertiary nitrogen atoms.

[0035] coolant

[0036] The present invention therefore relates to aqueous coolants which contain, as freezing point lowering glycol component, at least one component selected from the group consisting of alkylene glycol, alkylene glycol monoalkyl ether and glycerol, preferably monoethylene glycol and / or monopropylene glycol, particularly preferably monoethylene glycol, and at least one polyethyleneimine (F), as described above.

[0037] Particularly preferred are coolants containing

[0038] - at least 40 to 90 wt%, preferably 45 to 80 and particularly preferably 50 to 70 wt% water (A)

[0039] - at least 30 to 60% by weight, preferably 35 to 55 and particularly preferably 40 to 50% by weight of alkylene glycol, alkylene glycol monoalkyl ether and glycerol (B), as inhibitors (C)

[0040] - (C1 ) optionally at least one inorganic compound selected from the group consisting of silicates, borates, nitrates, molybdates and phosphates

[0041] - (C2a) optionally benzoic acid as aromatic monocarboxylic acid - (C2b) optionally at least one aliphatic monocarboxylic acid,

[0042] - (C3) optionally at least one organic dicarboxylic acid having 4 to 20 carbon atoms

[0043] - (C4) at least 0.005 to 5% by weight, preferably at least 0.0075 to 2.5% by weight, particularly preferably at least 0.01 to 1% by weight of at least one azole compound, preferably at least one triazole compound

[0044] - (C5) optionally at least one organic amine

[0045] - (D) optionally at least one inorganic base

[0046] - (E) optionally at least one other ingredient selected from the group consisting of hard water stabilizers, defoamers, colorants and bittering agents,

[0047] - 0.01 to 5, preferably 0.05 to 4 and particularly preferably 0.1 to 3 wt% of at least one polyethyleneimine (F), with the proviso that the sum of all components always amounts to 100 wt%.

[0048] If inorganic compounds (C1) are present in the coolant according to the invention, they are present in amounts of 0.1 to 5, preferably 0.2 to 4 and particularly preferably in amounts of 0.25 to 3 wt%.

[0049] In a preferred embodiment, no inorganic compound (C1) is present in the coolants, concentrates or superconcentrates according to the invention.

[0050] If acids (C2a), (C2b) and / or (C3) are present in the coolant according to the invention, then in amounts of 0.1 to 5, preferably 0.2 to 4 and particularly preferably in amounts of 0.25 to 3 wt%.

[0051] Among the acids (C2a), (C2b) and (C3), the aliphatic monocarboxylic acids (C2b) and organic dicarboxylic acids (C3) are preferred, in particular the aliphatic monocarboxylic acids (C2b).

[0052] In order to limit the formation of ion-forming species to a minimum, the molar ratio of tertiary amino groups in the polyethyleneimine (F) and optional organic amine (C5) (in total) to acids (C2a), (C2b) and (C3) (in total) is preferably from 1:0.01 to 1:0.5, particularly preferably from 0.02 to 0.4, very particularly preferably from 0.05 to 0.3, in particular from 0.05 to 0.25 and especially from 0.075 to 0.2.

[0053] If inorganic bases (D) are present in the coolant according to the invention, they are present in amounts of 0.1 to 5, preferably 0.2 to 4 and particularly preferably in amounts of 0.25 to 3 wt%.

[0054] Components

[0055] (A) Water

[0056] The water used in the present invention should be neutral with a pH of around 7. This can be demineralized or distilled water, although this is not mandatory. To enable use in hard water, the composition according to the invention generally contains at least one hard water stabilizer (see below).

[0057] (B) Alkylene glycol, alkylene glycol monoalkyl ether and glycerin

[0058] Component (B) causes the main freezing point depression in the coolants.

[0059] Component (B) preferably contains at least partially monoethylene glycol and / or monopropylene glycol, preferably monoethylene glycol.

[0060] In addition to monoethylene glycol and / or monopropylene glycol, component (B) may also contain other alkylene glycols, alkylene glycol monoalkyl ethers or glycerin.

[0061] In a preferred embodiment of the present invention, however, component (B) consists exclusively of monoethylene glycol and / or monopropylene glycol, preferably monoethylene glycol. Depending on the manufacturing process, these compounds may contain minor amounts of even higher homologues of the respective alkylene glycols, for example diethylene glycol or dipropylene glycol.

[0062] The individuals as component (B) are monomeric to tetrameric 1,2-ethylene glycols, 1,2-propylene glycols or, more rarely, 1,3-propylene glycols, preferably monomeric to trimeric 1,2-ethylene glycols or 1,2-propylene glycols, particularly preferably monomeric or dimeric 1,2-ethylene glycols, very particularly preferably monomeric 1,2-ethylene glycol, and in each case mixtures thereof.

[0063] The alkylene glycol monoalkyl ethers are the mono-Ci-C4-alkyl ethers of the above-mentioned alkylene glycols, preferably the monomethyl, ethyl or n-butyl ethers, particularly preferably the monomethyl or n-butyl ethers and very particularly preferably the monomethyl ethers.

[0064] Furthermore, glycerol or glycerol oligomers are possible components (B).

[0065] Preferred alkylene glycol components or derivatives are in particular monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and mixtures thereof, but also monopropylene glycol, dipropylene glycol and mixtures thereof, polyglycols, 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, each used alone or as mixtures thereof.

[0066] Particularly preferred are monoethylene glycol alone or mixtures of monoethylene glycol as the main component, ie with a content in the mixture of more than 50 wt.%, in particular more than 80 wt.%, especially more than 95 wt.%, with other alkylene glycols or derivatives of alkylene glycols.

[0067] When using monoethylene glycol as a freezing point-depressant compound, the content of higher ethylene glycol oligomers therein, i.e. diethylene glycol, triethylene glycol, etc., is in total less than 5% by weight, preferably less than 2.5% by weight, particularly preferably less than 1% by weight and most particularly preferably less than 0.5% by weight.

[0068] Industrially, monoethylene glycol is usually produced by opening ethylene oxide with water, whereby the ethylene oxide is produced from ethylene, which in turn is obtained by cracking fossil naphtha in steamer fields.

[0069] It is also conceivable to add feedstocks based on renewable resources to the fossil feedstock in the steam cracker, so that the resulting ethylene contains a proportion of bio-based material. This means that the monoethylene glycol obtained in this way contains a proportion of fossil and a proportion of bio-based monoethylene glycol.

[0070] In a further embodiment, the monoethylene glycol can also be obtained partially or completely, preferably completely, from renewable raw materials. The monoethylene glycol obtained from renewable raw materials can be characterized in that the 14 C / 12 C isotope ratio is determined, preferably according to ASTM D 6866 ("Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis").

[0071] According to this test method, the 14 C / 12C isotope ratio of a sample measured and compared with the 14 C / 12 C isotope ratio in a standardized 100% bio-based material. The result is the bio-based content in the sample.

[0072] This indicator is expressed as a percentage using the unit "pMC" (percent modern carbon). If the material being analyzed is a mixture of present-day radiocarbon and fossil carbon (with very low radiocarbon content), the resulting pMC value correlates directly with the amount of biomass material present in the sample.

[0073] "Bio-based materials" are organic materials made from carbon derived from CO2 recently (on a human timescale) fixed from the atmosphere through solar energy (photosynthesis). On land, this CO2 is absorbed or fixed by plants (e.g., lichens).

[0074] B. agricultural crops or forest plantations). In the oceans, CO2 is bound or fixed by photosynthesis in and by bacteria or phytoplankton. Thus, a bio-based material has an isotope ratio of 14 C / 12 C greater than 0. In contrast, a fossil material has a 14 C / 12 C isotope ratio of about 0.

[0075] In a preferred embodiment, the monoethylene glycol used in the coolants according to the invention has a bio-based content, measured as 14 C: 12 C ratio ASTM-D6866 of more than 0%, preferably at least 1%, more preferably at least 5%, most preferably at least 10%, in particular at least 20% and especially at least 25%.

[0076] Advantageously, this bio-based proportion can be at least 30%, preferably at least 40%, particularly preferably at least 50%, most particularly preferably at least 66%, in particular at least 75% and especially at least 85%.

[0077] A proportion of at least 90%, preferably at least 95%, particularly preferably at least 98%, and even 100% can be described as predominantly or entirely bio-based monoethylene glycol. The monoethylene glycol used in the coolants can be obtained entirely from renewable raw materials or consist of blends of monoethylene glycol from renewable and fossil sources.

[0078] Possibilities for producing such bio-based monoethylene glycol are described in the unpublished European patent application with the file number 23185804.4 and the filing date of July 17, 2023, and the unpublished International patent application with the file number PCT / EP2024 / 069303 and the filing date of July 9, 2024.

[0079] Inhibitors (C)

[0080] The inhibitors (C) act as corrosion inhibitors against metal corrosion, for example of ferrous materials, aluminum, non-ferrous metals or solder.

[0081] The compositions according to the invention contain at least one of the inhibitors listed below:

[0082] - (C1 ) optionally at least one inorganic compound selected from the group consisting of silicates, borates, nitrates, molybdates and phosphates and organic silicic acid esters

[0083] - (C2a) optionally benzoic acid as aromatic monocarboxylic acid

[0084] - (C2b) optionally at least one aliphatic monocarboxylic acid

[0085] - (C3) optionally at least one organic dicarboxylic acid having 4 to 20 carbon atoms

[0086] - (C4) at least one azole, preferably at least one triazole compound,

[0087] - (C5) optionally at least one organic amine.

[0088] Inorganic inhibitors (C1)

[0089] The inorganic inhibitors (C1) are silicates, borates, nitrates, molybdates, or phosphates, or mixtures thereof in the form of their free acids or their salts, especially their alkali metal salts, particularly preferably their sodium or potassium salts. The form (protonated or salt) in which they are present in the compositions, superconcentrates, concentrates, or coolants depends on the respective pK. sThe pH value of the compound and its composition, as well as the pH of the respective environment, which is determined by the amount of base (D). Inorganic silicates primarily act as aluminum corrosion inhibitors and are usually used as alkali metal salts or, less frequently, as magnesium, calcium, or aluminum salts, preferably as sodium or potassium salts.

[0090] The silicates are preferably selected from the group consisting of orthosilicates (SiO / -), metasilicates (SiOs 2 "), and pyrosilicates (Si2O? 6 "), particularly preferably metasilicates (SiOs 2 "), very particularly preferably sodium metasilicate (NasSiOs) or potassium metasilicate (K2SiOs), in particular sodium metasilicate (NasSiOs).

[0091] If the composition according to the invention contains at least one inorganic silicate or one organic silicic acid ester, in a preferred embodiment at least one silicophosphonate is added in addition to the silicate, as described in EP 4015596 or in WO 2022 / 043303 for silicic acid esters.

[0092] Preferably, the silicophosphonate is a compound of the general formula

[0093] OR 6 ß leil>

[0094] R- - O - - R- - P - O l8h OR OR wherein

[0095] R 5 is a divalent organic radical, preferably a 1,w-alkylene group having 1 to 6, preferably 1 to 4 carbon atoms, particularly preferably methylene, 1,2-ethylene, 1,2-propylene, 1,3-propylene or 1,4-butylene, very particularly preferably 1,2-ethylene or 1,3-propylene and in particular 1,2-ethylene,

[0096] R 6independently of one another hydrogen, C1- to C4-alkyl or hydroxy-C2- to C4-alkyl, preferably hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl, 2-hydroxyethyl or 2-hydroxypropyl, particularly preferably hydrogen, methyl, ethyl or propyl, and R 7 is C1- to C4-alkyl, preferably methyl, ethyl, n-propyl or n-butyl, particularly preferably methyl, ethyl or n-butyl, very particularly preferably methyl or ethyl, and especially methyl. The silicophosphonates can be used as the free acid or as the alkali metal salt, preferably as the sodium or potassium salt, and particularly preferably as the sodium salt.

[0097] The borates are preferably used as sodium tetraborate (borax) or as potassium tetraborate, particularly preferably as sodium tetraborate.

[0098] The nitrates are used as alkali or alkaline earth metal nitrates, preferably as sodium nitrate, potassium nitrate or magnesium nitrate, preferably as sodium nitrate or potassium nitrate, particularly preferably as sodium nitrate.

[0099] The phosphates are used as free acid (H3PO4), as hydrogen phosphate, dihydrogen phosphate or phosphate, preferably as sodium or potassium salt.

[0100] The use of the corresponding diphosphates, triphosphates or oligophosphates is also conceivable, but they are preferably used as monomeric phosphates.

[0101] It is preferred to use it as free acid (H3PO4), disodium hydrogen phosphate or trisodium phosphate.

[0102] Esters of orthosilicic acid are compounds of the formula

[0103] Si(OR 1 )4wherein

[0104] R 1is an organic substituent having 1 to 6 carbon atoms, for example a linear or branched, preferably a linear alkyl substituent having 1 to 6 carbon atoms or an aromatic substituent having 6 carbon atoms, particularly preferably an alkyl substituent having 1 to 4 carbon atoms and very particularly preferably an alkyl substituent having 1 or 2 carbon atoms.

[0105] Alkoxyalkylsilanes are less preferred, and both the alkoxy substituent and the alkyl group comprise a linear or branched, preferably a linear alkyl substituent having 1 to 6 carbon atoms, more preferably an alkyl substituent having 1 to 4 carbon atoms, and most preferably an alkyl substituent having 1 or 2 carbon atoms. Typical examples of esters of orthosilicic acid are tetraalkoxysilanes, preferably tetramethoxysilane and tetraethoxysilane, and alkoxyalkylsilanes, preferably triethoxymethylsilane, diethoxydim-methylsilane, ethoxytrimethylsilane, trimethoxymethylsilane, dimethoxydimethylsilane, and methoxytrimethylsilane. Tetraalkoxysilanes are preferred, more preferably tetramethoxysilane and tetraethoxysilane, with tetraethoxysilane being most preferred.

[0106] The components (C1) are preferably at least one compound selected from the group consisting of silicates, borates, nitrates or phosphates, particularly preferably at least one compound selected from the group consisting of silicates, nitrates or phosphates.

[0107] (C2a) Aromatic monocarboxylic acid

[0108] The optional aromatic monocarboxylic acid is preferably benzoic acid, which can be used as the free acid or particularly preferably in the form of its alkali metal salt, most preferably as sodium benzoate.

[0109] In a preferred embodiment of the present invention, no aromatic monocarboxylic acid is present.

[0110] (C2b) Aliphatic monocarboxylic acids

[0111] Aliphatic monocarboxylic acids are organic aliphatic alkane or alkenecarboxylic acids. Provided they are sufficiently water-soluble, they are frequently used in coolants as corrosion inhibitors against the corrosion of ferrous materials. These aliphatic monocarboxylic acids preferably have 5 to 12 carbon atoms, more preferably 6 to 10, and most preferably 8, 9, or 10.

[0112] Typical such monocarboxylic acids are pentanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, 2,2-dimethylbutanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, decanoic acid, undecanoic acid and dodecanoic acid, as well as their isomer mixtures, in particular 2-ethylhexanoic acid and isononanoic acid isomer mixtures.

[0113] However, one possible embodiment is to use the aliphatic monocarboxylic acids in the form of their alkali metal salts, preferably in the form of their lithium, sodium, or potassium salts, particularly preferably in the form of their sodium or potassium salts, instead of the free acid. (C3) Organic dicarboxylic acid containing 4 to 20 carbon atoms

[0114] The organic dicarboxylic acids having 4 to 20 carbon atoms are linear or branched alkanedicarboxylic acids, preferably linear alkane or alkenedicarboxylic acids, particularly preferably alkanedicarboxylic acids, particularly preferably having 5 to 14 and very particularly preferably having 6 to 12 carbon atoms.

[0115] Preferably, the dicarboxylic acids (C3) are selected from the group consisting of succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid (heptanedioic acid), azelaic acid (nonanedioic acid), sebacic acid (decanedioic acid), undecanedioic acid, dodecanedioic acid, as well as alkyl and alkenyl succinic acids and glutaric acids such as 2-methylbutanedioic acid, 2-ethyl-3-methylbutanedioic acid, 2-ethylpentanedioic acid, 2-dodecylbutanedioic acid, 2-dodecenylbutanedioic acid, 2-phenylbutanedioic acid, 2-(p-methylphenyl)butanedioic acid, 2,2-dimethylbutanedioic acid, 2,3,4-trimethylpentanedioic acid, 2,2,3-trimethylpentanedioic acid, glutaconic acid (pent-2-enedioic acid), itaconic acid, Hex-2-enedioic acid, hex-3-enedioic acid, 5-methyl-hex-2-enedioic acid and 2,3-dimethyl-pent-2-enedioic acid.

[0116] Among these, preferred are the dicarboxylic acids having 6 to 12 carbon atoms, particularly preferred among these are the alkanedicarboxylic acids having 6 to 12 carbon atoms, very particularly preferred are the linear alkanedicarboxylic acids having 6 to 12 carbon atoms.

[0117] Particularly preferred dicarboxylic acids (D3) are adipic acid, sebacic acid, azelaic acid and dodecanedicarboxylic acid.

[0118] (C4) Azole compound

[0119] In the context of this document, azole derivatives (C4) are defined as five-membered heterocyclic compounds with 2 or 3 heteroatoms from the group nitrogen and sulfur, which contain no or a maximum of one sulfur atom incorporated into the ring and which can optionally carry an aromatic or saturated six-membered anellant.

[0120] These five-membered heterocyclic compounds (azole derivatives) usually contain two N atoms and no S atom, three N atoms and no S atom, or one N atom and one S atom as heteroatoms. Preferred groups of the above-mentioned azole derivatives are fused imidazoles and fused 1,2,3-triazoles of the general formula or (IV) in which the variable

[0121] R represents hydrogen or a Ci- to Cw-alkyl radical, in particular methyl or ethyl, and the variable X represents a nitrogen atom or the group CH.

[0122] Typical and preferred examples of azole derivatives of the general formula (III) are benzimidazole (X = CH, R = H), benzotriazole (X = N, R = H), and tolutriazole (tolyltriazole) (X = N, R = CH3). A typical example of an azole derivative of the general formula (IV) is hydrogenated 1,2,3-tolutriazole (tolyltriazole) (X = N, R = CH3).

[0123] Another preferred group of the azole derivatives mentioned are benzothiazoles of the general formula (V) in which the variable R has the meaning given above and the variable R' denotes hydrogen, a Ci- to Cw-alkyl radical, in particular methyl or ethyl, or in particular a mercapto group (-SH). Conceivably, although less preferably, R' can also be a carboxyalkyl radical of the formula -(C m H2m)-COOR", where m is a number from 1 to 4 and R" is hydrogen or C1- to C2-alkyl, in particular methyl or ethyl, or C5- to C12-aryl. Examples of these are (2-benzothiazylthio)acetic acid, (2-benzothiazylthio)acetic acid ester, 3-(2-benzothiazylthio)propionic acid or 3-(2-benzothiazylthio)propionic acid ester. In the event that these compounds are used as acid, they are not among the carboxylic acids excluded according to the invention. A typical example of an azole derivative of the general formula (V) is 2-mercaptobenzothiazole.

[0124] Furthermore, non-fused azole derivatives of the general formula (VI)

[0125] (VI) in which the variables

[0126] X and Y together denote two nitrogen atoms or one nitrogen atom and a group CH, for example 1 H-1,2,4-triazole (X = Y = N) or preferably imidazole (X = N, Y = CH).

[0127] Benzimidazole, benzotriazole, tolutriazole, hydrogenated tolutriazole or mixtures thereof, in particular benzotriazole or tolutriazole, especially tolutriazole, are very particularly preferred as azole derivatives for the present invention.

[0128] The azole derivatives mentioned are commercially available or can be prepared using conventional methods. Hydrogenated benzotriazoles such as hydrogenated tolutriazole are also accessible according to DE-A 1 948 794 and are also commercially available.

[0129] Preferably, the azoles are selected from the group consisting of benzotriazole, tolutriazole, (2-benzothiazylthio)acetic acid, 3-(2-benzothiazylthio)propionic acid and 2-mercaptobenzothiazole.

[0130] (C5) Organic amine

[0131] The amines (C5) preferably have 2 to 9, in particular 4 to 8, carbon atoms. The amines (C5) are preferably tertiary amines. The amines (C5) preferably contain 0 to 3 ether oxygen atoms or 0 to 3, preferably 0 to 2, hydroxyl groups. Typical examples of amines (C5) are ethylamine, propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, 2-ethylhexylamine, n-nonylamine, isononylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, mono-, di-, and triethanolamine, mono-, di-, and triisopropanolamine, C4-C12-alkyl diethanolamine, C1-C12-alkyl diisopropanolamine, piperidine, morpholine, cyclohexylamine, aniline, and benzylamine. Aliphatic and cycloaliphatic amines (C5) are generally saturated.

[0132] The amines (C5) are preferably selected from the group consisting of diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, C4-C-alkyl diethanolamine, C1-C10-alkyl diisopropanolamine, particularly preferably selected from the group consisting of triethanolamine, diisopropanolamine, C4-C8-alkyl diethanolamine, Ci-C4-alkyl diisopropanolamine, very particularly preferably selected from the group consisting of triethanolamine, diisopropanolamine, N-methyl diisopropanolamine, N-butyl diethanolamine and N-octyl diethanolamine.

[0133] In a preferred embodiment, at least one organic amine is contained in the coolants according to the invention in addition to the polyethyleneimines, particularly preferably in amounts of 0.01 to 3 wt%, preferably at least 0.02 to 2 wt%, particularly preferably at least 0.05 to 1 wt%.

[0134] (D) Inorganic base

[0135] The pH value of the antifreeze at the end user is usually in the range of 4 to 11.5, preferably 5 to 10, in particular 6 to 9.

[0136] In order to adjust this pH value, at least one inorganic base (D) is added at any stage in the production process for the coolant from a concentrated precursor. The at least one inorganic base can be present in the composition according to the invention, in the superconcentrate or in the concentrate, or can be added during the production of the superconcentrate from the composition according to the invention by mixing with component (A) and / or (B), during the production of the concentrate from the superconcentrate by mixing with component (A) and / or (B), or during the production of the coolant from the concentrate by mixing with component (A) and / or (B). Therefore, the compositions according to the invention optionally contain an amount of inorganic base which, when appropriately diluted in the coolant, adjusts this desired pH value.For this purpose, the compositions according to the invention preferably contain alkali metal hydroxide, particularly preferably solid lithium, sodium or potassium hydroxide, optionally also in the form of aqueous lithium, sodium or potassium hydroxide solution.

[0137] Less preferred are carbonates or bicarbonates of lithium, sodium or potassium.

[0138] Preferred alkali metals are sodium and potassium.

[0139] (E) Optional other ingredients selected from the group consisting of hard water stabilizers, defoamers, colorants and bittering agents

[0140] As further conventional auxiliaries, the compositions according to the invention may also contain defoamers in small amounts (generally in amounts of 0.003 to 0.008 wt.% in the final diluted coolant), as well as bittering agents (e.g., of the denatonium benzoate type) and dyes for reasons of hygiene and safety in case of ingestion. In a preferred embodiment of the present invention, at least one bittering agent is present, preferably at least one bittering agent and one dye, particularly preferably at least one bittering agent, dye, and defoamer.

[0141] The composition may also contain one or more hard water stabilizers 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. The proportion in the composition is selected so that, after appropriate dilution, the amount in the final diluted coolant is up to 1 wt.%.

[0142] Concentrates, sugar concentrates

[0143] To reduce the volumes to be transported, coolants with high water content are usually not sold, but rather concentrates in which the water content is omitted or significantly reduced. The coolants are manufactured by the end user from the concentrates by adding water.

[0144] To further reduce the volumes to be transported, so-called super concentrates are often produced centrally. These super concentrates omit or significantly reduce not only the water but also the glycol content. These super concentrates are then produced regionally by formulators by blending them with glycols.

[0145] A further subject of the present invention are therefore coolant concentrates containing

[0146] - not more than 15, preferably not more than 10 and particularly preferably not more than 5 wt% water (A)

[0147] - at least 50, preferably at least 60, particularly preferably at least 70 wt% of at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol (B) as inhibitors (C)

[0148] - (C1) optionally at least one inorganic compound selected from the group consisting of silicates, borates, nitrates, molybdates and phosphates

[0149] - (C2a) optionally benzoic acid as aromatic monocarboxylic acid

[0150] - (C2b) optionally at least one aliphatic monocarboxylic acid,

[0151] - (C3) optionally at least one organic dicarboxylic acid having 4 to 20 carbon atoms

[0152] - (C4) at least one azole, preferably at least one triazole compound

[0153] - (C5) optionally at least one organic amine,

[0154] - (D) optionally at least one inorganic base

[0155] - (E) optionally at least one other ingredient selected from the group consisting of hard water stabilizers, defoamers, colorants and bittering agents, and

[0156] - 0.02 to 10, preferably 0.1 to 8 and particularly preferably 0.2 to 6 wt% of at least one polyethyleneimine (F).

[0157] If inorganic compounds (C1) are contained in the concentrate, then in amounts of 0.2 to 10, preferably 0.4 to 8 and particularly preferably in amounts of 0.5 to 6 wt%.

[0158] If acids (C2a), (C2b) and / or (C3) are contained in the concentrate, then in amounts of 0.2 to 10, preferably 0.4 to 8 and particularly preferably in amounts of 0.5 to 6 wt%.

[0159] If organic amines (C5) are present in the concentrate, they are present in amounts of 0.02 to 6 wt%, preferably at least 0.04 to 4 wt%, particularly preferably at least 0.1 to 2 wt%. If inorganic bases (D) are present in the concentrate, they are present in amounts of 0.2 to 10 wt%, preferably 0.4 to 8 wt%, and particularly preferably 0.5 to 6 wt%.

[0160] Another object of the present invention are coolant superconcentrates containing

[0161] - not more than 15, preferably not more than 10 and particularly preferably not more than 5 wt% water (A)

[0162] - at least 50, preferably at least 60, particularly preferably at least 70 wt% of at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol (B) as inhibitors (C)

[0163] - (C1 ) optionally at least one inorganic compound selected from the group consisting of silicates, borates, nitrates, molybdates and phosphates

[0164] - (C2a) optionally benzoic acid as aromatic monocarboxylic acid

[0165] - (C2b) optionally at least one aliphatic monocarboxylic acid,

[0166] - (C3) optionally at least one organic dicarboxylic acid having 4 to 20 carbon atoms

[0167] - (C4) at least one azole, preferably at least one triazole compound

[0168] - (C5) optionally at least one organic amine

[0169] - (D) optionally at least one inorganic base

[0170] - (E) optionally at least one other ingredient selected from the group consisting of hard water stabilizers, defoamers, colorants and bittering agents and

[0171] - 0.03 to 30, preferably 0.15 to 24 and particularly preferably 0.3 to 18 wt% of at least one polyethyleneimine (F).

[0172] If inorganic compounds (C1) are contained in the super concentrate, then in amounts of 0.4 to 20, preferably 0.8 to 16 and particularly preferably in amounts of 1.5 to 18 wt%.

[0173] If acids (C2a), (C2b) and / or (C3) are contained in the super concentrate, then in amounts of 0.4 to 20, preferably 0.8 to 16 and particularly preferably in amounts of 1.5 to 18 wt%.

[0174] If organic amines (C5) are present in the superconcentrate, they are present in amounts of 0.03 to 9 wt%, preferably at least 0.06 to 6 wt%, particularly preferably at least 0.15 to 3 wt%. If inorganic bases (D) are present in the superconcentrate, they are present in amounts of 0.4 to 20 wt%, preferably 0.8 to 16 wt%, and particularly preferably 1.5 to 18 wt%.

[0175] A further object of the present invention is a process for producing the above-mentioned coolant concentrates from the above-mentioned coolant superconcentrates, in which a coolant superconcentrate is mixed with the appropriate amount of at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol (B).

[0176] Examples

[0177] (*) The polyethyleneimine is a 50% aqueous solution of a polyethyleneimine with a molecular weight Mw of 5000 g / mol (determined by GPC), a pH of 11 and a ratio of primary : secondary : tertiary amino groups (per 13 C-NMR) of 1 : 1 : 0.7.

[0178] Example 1 represents a base formulation without polyethyleneamine. Examples 2-4 describe the addition of polyethyleneamine at different concentrations. It is clear that the addition of polyethyleneamine significantly reduces the corrosion rate on aluminum according to ASTM D1384. At the same time, the effect on electrical conductivity is small.

Claims

Claims 1. Coolant containing - at least 40% water by weight (A) - at least 30% by weight of alkylene glycol, alkylene glycol monoalkyl ether and glycerol (B), - 0.1 to 5 wt% of at least one acid selected from the group consisting of - - (C2a) Benzoic acid as aromatic monocarboxylic acid, - - (C2b) at least one aliphatic monocarboxylic acid and - - (C3) at least one organic dicarboxylic acid having 4 to 20 carbon atoms, - at least 0.01 to 5 wt% of at least one polyethyleneimine (F).

2. Coolant according to claim 1, characterized in that the polyethyleneimine (F) is selected from the group consisting of the formula (I) where x and y are independently 0 (zero) or a positive integer mean, with the proviso that - in formula (II) the sum of x and y is not 0 (zero).

3. Coolant according to claim 2, characterized in that, independently of one another, x is at least 1, particularly preferably at least 2, very particularly preferably at least 3, in particular at least 5 and especially at least 10, y is at least 1, particularly preferably at least 2, very particularly preferably at least 3, in particular at least 5 and especially at least 10, x and y can, independently of one another, be up to 1500, preferably up to 1400, particularly preferably up to 1300, very particularly preferably up to 1200, in particular up to 1000 and especially up to 750.

4. Coolant according to claim 1, characterized in that the 13 C-NMR The ratio of primary to secondary to tertiary nitrogen atoms in the polyethyleneimines, as determined by spectroscopy, is preferably 1:0.5 to 1.5:0.3 to 0.9, preferably 1:0.6 to 1.3:0.4 to 0.8, more preferably 1:0.7 to 1.3:0.4 to 0.8 and in particular 1:0.9 to 1.1:0.5 to 0.

8.

5. Coolant according to one of the preceding claims, characterized in that the weight-average molar masses (Mw measured by GPC) of the polyethyleneimines (F) are at least 500, preferably at least 750 and very particularly preferably at least 1000 g / mol and less than 55 000 g / mol, preferably less than 40 000, even more preferably less than 30 000 and even more preferably less than 15 000 g / mol.

6. Coolant according to one of the preceding claims, additionally containing at least one of the following components as inhibitors (C) - (C1) optionally at least one inorganic compound selected from the group consisting of silicates, borates, nitrates, molybdates and phosphates - (C2a) optionally benzoic acid as aromatic monocarboxylic acid - (C2b) optionally at least one aliphatic monocarboxylic acid, - (C3) optionally at least one organic dicarboxylic acid having 4 to 20 carbon atoms - (C4) at least one azole compound, preferably at least one triazole compound - (C5) optionally at least one organic amine - (D) optionally at least one inorganic base - (E) optionally at least one other ingredient selected from the group consisting of hard water stabilizers, defoamers, colorants and bittering agents.

7. Coolant according to one of the preceding claims, characterized in that at least one aliphatic monocarboxylic acid (C2b) is present, preferably selected from the group consisting of pentanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, 2,2-dimethylbutanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, decanoic acid, undecanoic acid and dodecanoic acid, and their isomer mixtures, particularly preferably 2-ethylhexanoic acid or isononanoic acid isomer mixtures, very particularly preferably isononanoic acid isomer mixtures.

8. Coolant according to one of the preceding claims, characterized in that no inorganic compound (C1) selected from the group consisting of silicates, borates, nitrates, molybdates and phosphates is present.

9. Coolant according to one of the preceding claims, characterized in that at least one organic amine (C5) is present, preferably selected from the group consisting of diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, C4-C10-alkyl diethanolamines and C1-C10-alkyl diisopropanolamines.

10. Coolant according to one of the preceding claims, characterized in that the The molar ratio of tertiary amino groups in the polyethyleneimine (F) and optional organic amine (C5) (in total) to acids (C2a), (C2b) and (C3) (in total) is preferably from 1:0.01 to 1:0.

5.

11. Use of polyethyleneimines (F) as described in any one of claims 1 to 6 in coolants for use in cooling systems of stationary engines or vehicles with internal combustion engines, electric motors, fuel cells or hybrid engines with a combination of internal combustion engines with electric motors or a combination of internal combustion engines with fuel cells or in generators, such as wind turbines.

12. Use according to claim 11, characterized in that the polymer (F) is used as Corrosion inhibitor is used.

13. Use according to claim 12, characterized in that the polymer (F) is used as Corrosion inhibitor for iron-containing and / or aluminum-containing materials.

14. Coolant concentrates containing - not more than 15, preferably not more than 10 and particularly preferably not more than 5 wt% water (A) - at least 50, preferably at least 60, particularly preferably at least 70 wt% of at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol (B) as inhibitors (C) - (C1) optionally at least one inorganic compound selected from the group consisting of silicates, borates, nitrates, molybdates and phosphates - (C2a) optionally benzoic acid as aromatic monocarboxylic acid - (C2b) optionally at least one aliphatic monocarboxylic acid, - (C3) optionally at least one organic dicarboxylic acid having 4 to 20 carbon atoms - (C4) at least one azole, preferably at least one triazole compound - (C5) optionally at least one organic amine - (D) optionally at least one inorganic base - (E) optionally at least one other ingredient selected from the group consisting of hard water stabilizers, defoamers, colorants and bittering agents, and - 0.1 to 10, preferably 0.2 to 8 and particularly preferably 0.5 to 6 wt% of at least one polyethyleneimine (F).

15. Coolant superconcentrates containing - not more than 15, preferably not more than 10 and particularly preferably not more than 5 wt% water (A) - at least 50, preferably at least 60, particularly preferably at least 70 wt% of at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol (B) as inhibitors (C) - (C1) optionally at least one inorganic compound selected from the group consisting of silicates, borates, nitrates, molybdates and phosphates - (C2a) optionally benzoic acid as aromatic monocarboxylic acid - (C2b) optionally at least one aliphatic monocarboxylic acid, - (C3) optionally at least one organic dicarboxylic acid having 4 to 20 carbon atoms - (C4) at least one azole, preferably at least one triazole compound - (C5) optionally at least one organic amine - (D) optionally at least one inorganic base - (E) optionally at least one other constituent selected from the group consisting of hard water stabilizers, defoamers, dyes and bittering agents and - 0.3 to 30, preferably 0.6 to 24 and particularly preferably 1.5 to 18 wt% of at least one polyethyleneimine (F).

16. A process for producing coolant concentrates according to claim 14 from coolant superconcentrates from claim 15, characterized in that a coolant superconcentrate is mixed with the corresponding amount of at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol (B).

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