Novel coolants exhibiting improved storage stability

Abstract

The present application describes coolants, corresponding coolant concentrates, and uses of such coolants that exhibit enhanced activity against corrosion of aluminum and aluminum alloys and improved storage stability.

Description

[Technical Field]

[0001] The present application describes coolants, corresponding coolant concentrates, and uses of such coolants that exhibit improved activity against corrosion of aluminum and aluminum alloys and improved storage stability. [Background technology]

[0002] In coolants, inorganic silicates are widely known as inhibitors against corrosion of aluminum surfaces in cooling systems.

[0003] A drawback of such inorganic silicates and orthosilicates is that their corrosion inhibitor activity in the coolant or coolant concentrate decreases during storage. Without wishing to be bound by theory, it is believed that only monomeric silicates and lower oligomeric silicates (e.g., dimers) are active corrosion inhibitors that lose activity upon formation of polymeric silicates, presumably by immobilization and / or precipitation from solution.

[0004] US 5,643,493 discloses an alcohol / glycol-based antifreeze agent-free corrosion inhibitor concentrate containing a silicate and also a stabilizer for the silicate against gelling (such stabilizer may be a silicon phosphonate, the chemical structure of which is not shown).

[0005] No disclosure is made regarding storage stability. Furthermore, the aqueous solution according to US 5,643,493 is not a refrigerant, nor is it a refrigerant concentrate that serves as the basis for a refrigerant; it is used as a "refrigerant additive aid" that is added to the refrigerant in use to neutralize decomposition products that accumulate in the system. Therefore, such refrigerant additive aids do not present the problems associated with glycol-based refrigerants.

[0006] WO 02 / 101848 discloses a coolant containing an azole derivative and an orthosilicate for cooling a fuel cell-powered device. Such orthosilicates (esters of orthosilicic acid) act as inhibitors against corrosion of aluminum surfaces and have the advantage of not containing an ionic charge, making them particularly suitable for coolants with low electrical conductivity.

[0007] Unpublished European Patent Application No. 20192954.4, filed August 26, 2020, discloses a coolant for the cooling system of a vehicle equipped with an electric engine, a fuel cell, or a hybrid engine combining a combustion engine with an electric engine or a combustion engine with a fuel cell, the coolant comprising an azole derivative, an alkoxyalkylsilane or an ester of orthosilicic acid, a specific tertiary amine, a monocarboxylic acid, and, optionally, at least one silicophosphonate.

[0008] In corrosion tests, compositions containing silicophosphonates showed less silicon loss from tetraethoxysilane during corrosion than those without silicophosphonates. This document is silent about inorganic silicates, nor about the storage stability of such coolants. Summary of the Invention

[0009] The object of the present invention was to provide a method for enhancing the storage stability of coolants and coolant concentrates which have good anticorrosion activity towards aluminum.

[0010] This problem is solved by the method described in claim 1.

[0011] Another subject of the invention is (A) at least one glycol; (B) Water; (C) at least one azole derivative; (D) optionally at least one inorganic silicate; (E) optionally at least one tertiary amine, preferably a tertiary amine containing at least one 2-hydroxyethyl or 2-hydroxypropyl group; (F) at least one carboxylic acid; (G) General structure (V): [ka] [In the formula, R 5 is a divalent organic group, preferably a 1,ω-alkylene group having 1 to 6, preferably 1 to 4 carbon atoms, more preferably methylene, 1,2-ethylene, 1,2-propylene, 1,3-propylene or 1,4-butylene, most preferably 1,2-ethylene or 1,3-propylene, in particular 1,2-ethylene; R 6 are, independently of one another, hydrogen, C1- to C4-alkyl or hydroxy-C2- to C4-alkyl, preferably hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, more preferably hydrogen, methyl, ethyl or propyl; and R 7 is C1- to C4-alkyl] at least one silicophosphonate of (H) At least one optional additional coolant additive. It is a coolant containing

[0012] Such coolants exhibit both good corrosion inhibitor activity, particularly against aluminum corrosion, and enhanced storage stability by maintaining the concentration of inorganic silicate (D) in the coolant during storage at a level sufficient to be effective against aluminum corrosion.

[0013] The details of the components are as follows:

[0014] Glycol (A) As alkylene glycol component or derivative thereof (A), it is possible to use, in particular, monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and mixtures thereof, and also monopropylene glycol, dipropylene glycol and mixtures thereof, 1,3-propanediol, higher polyalkylene glycols, alkylene glycol ethers such as monoethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, monoethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, monoethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether or glycerol (in each case alone or mixtures thereof).

[0015] Water (B) The water used in the coolant according to the present invention should be neutral with a pH value of about 7.

[0016] If hard water is used, it is possible to add hard water stabilizers to the coolant, which may be based, for example, on polyacrylic acid, polymaleic acid, acrylic acid-maleic acid copolymers, polyvinylpyrrolidone, polyvinylimidazole, vinylpyrrolidone-vinylimidazole copolymers and / or copolymers of unsaturated carboxylic acids with olefins.

[0017] Azole derivatives (C) Azole derivatives in the context of the present invention mean five-membered heterocyclic compounds having two or three heteroatoms from the group consisting of nitrogen and sulfur, which may contain no sulfur atoms or at most one sulfur atom and may have an aromatic or saturated six-membered fused ring.

[0018] These five-membered heterocyclic compounds (azole derivatives) can generally contain two N atoms and no S atoms, three N atoms and no S atoms, or one N atom and one S atom as heteroatoms.

[0019] A preferred group of azole derivatives identified are those of the general formula [ka] [In the formula, The variable R is hydrogen or C1-C 10 - an alkyl group, in particular methyl or ethyl, The variable group X is a nitrogen atom or a CH group. These are annelated imidazoles and annelated 1,2,3-triazoles.

[0020] Typical and preferred examples of the azole derivatives of general formula (I) are benzimidazole (X=CH, R=H), benzotriazole (X=N, R=H) and tolutriazole (X=N, R=CH). A typical example of the azole derivatives of general formula (II) is hydrogenated 1,2,3-tolutriazole (X=N, R=CH).

[0021] Another preferred group of azole derivatives identified is represented by the general formula (III) [ka] [In the formula, The variable R has the same meaning as above, The variable group R' is hydrogen, C1-C 10 - an alkyl group, in particular methyl or ethyl, or in particular a mercapto group (-SH). A typical example of an azole derivative of general formula (III) is 2-mercaptobenzothiazole.

[0022] In a preferred embodiment, it is also possible to use (2-benzothiazylthio)acetic acid (R' = -S-CH2-COOH) or (2-benzothiazylthio)propionic acid (R' = -S-CH2-CH2-COOH).

[0023] Further suitable azole derivatives are those of the general formula (IV) [ka]

[0024] wherein the variables X and Y together are two nitrogen atoms or one nitrogen atom and a CH group, e.g., 1H-1,2,4-triazole (X=Y=N), or preferably imidazole (X=N, Y=CH). It is a non-anenated azole derivative of

[0025] For the purposes of the present invention, benzimidazole, benzotriazole, tolutriazole, hydrogenated tolutriazole, (2-benzothiazylthio)acetic acid or (2-benzothiazylthio)propionic acid or mixtures thereof, in particular benzotriazole or tolutriazole, are very particularly preferred as azole derivatives.

[0026] The azole derivatives described are commercially available or can be prepared by conventional methods. Hydrogenated benzotriazoles, such as hydrogenated tolutriazole, are likewise available as described in DE-A 1 948 794 and are also commercially available.

[0027] Inorganic Silicate (D) In the context of the present invention, inorganic silicates are silicon compounds consisting exclusively of elements selected from the group consisting of silicon, oxygen, hydrogen and metals from main groups I, II, and III (IUPAC groups 1, 2, and 13) of the periodic table of the elements.

[0028] Preferred metals from main group I are lithium, sodium and potassium, more preferably sodium and potassium. Preferred metals from main group II are magnesium and calcium. Preferred metals from main group III are boron and aluminum.

[0029] More preferred metals are those from main groups I and II, most preferably those from main group I.

[0030] Particularly preferred metals are sodium and potassium.

[0031] In a preferred embodiment, the inorganic silicate (D) is an orthosilicate (SiO 4- ), metasilicate (SiO3 2- ) and pyrosilicate (Si2O7 6- ), more preferably metasilicate (SiO 2- ), most preferably sodium metasilicate (Na2SiO3) or potassium metasilicate (K2SiO3), especially sodium metasilicate (Na2SiO3).

[0032] Compound (D) is primarily used as an inhibitor of aluminum corrosion.

[0033] Tertiary amine (E) The optional compound (E) is a tertiary amine, preferably a tertiary amine containing at least one 2-hydroxyethyl or 2-hydroxypropyl group.

[0034] In a preferred embodiment of the present invention, no tertiary amine (E) is present in the coolant.

[0035] Preferred tertiary amines (E) contain at least one 2-hydroxyethyl or 2-hydroxypropyl group. Possible tertiary amines (E) may contain 1, 2 or 3 2-hydroxyethyl or 2-hydroxypropyl groups, preferably 2 or 3 2-hydroxyethyl or 2-hydroxypropyl groups, more preferably 2-hydroxyethyl groups.

[0036] Substituents of the tertiary amine (E) that are not 2-hydroxyethyl or 2-hydroxypropyl groups may be aliphatic, alicyclic or aromatic groups having up to 20 carbon atoms, preferably up to 18, more preferably up to 16, even more preferably up to 14 and especially up to 12 carbon atoms.

[0037] These substituents are preferably aliphatic or aromatic, more preferably aliphatic.

[0038] The aromatic substituent can be, for example, phenyl, tolyl, or naphthyl.

[0039] The aliphatic substituents can be linear or branched and are preferably linear alkyl substituents containing from 1 to 18 carbon atoms, preferably from 2 to 16, more preferably from 4 to 14, especially from 6 to 12 carbon atoms.

[0040] In compounds (E), the substituents are preferably derived from aliphatic amines, which are preferably obtainable by hydrogenation and amination of fatty acids and esters, particularly preferably by hydrogenation and amination of: 2-ethylhexanoic acid, octanoic acid (caprylic acid), pelargonic acid (nonanoic acid), 2-propylheptanoic acid, decanoic acid (capric acid), undecanoic acid, dodecanoic acid (lauric acid), tridecanoic acid, tetradecanoic acid (myristic acid), pentadecanoic acid, palmitic acid (hexadecanoic acid), palmitoleic acid [(9Z)-hexadec-9-enoic acid], margaric acid (heptadecanoic acid), stearic acid (octadecanoic acid), oleic acid [(9Z)-octadec-9-enoic acid], elaidic acid [(9E)-octadeca-9-enoic acid]. -enoic acid], linoleic acid [(9Z,12Z)-octadeca-9,12-dienoic acid], linolenic acid [(9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid], eleostearic acid [(9Z,11E,13E)-octadeca-9,11,13-trienoic acid], ricinoleic acid ((R)-12-hydroxy-(Z)-octadec-9-enoic acid), isoricinoleic acid [(S)-9-hydroxy-(Z)-octadec-12-enoic acid], nonadecanoic acid, arachidic acid (eicosanoic acid), behenic acid (docosanoic acid), and erucic acid [(13Z)-docos-13-enoic acid].

[0041] Examples of tertiary amines (E) containing one 2-hydroxyethyl or 2-hydroxypropyl group and two other substituents include those of the general formula (I): [ka] [In the formula, R 2 and R 3 are, independently of one another, the above-mentioned substituents, preferably linear or branched, preferably linear alkyl substituents, containing 1 to 18 carbon atoms, preferably 2 to 16, more preferably 4 to 14, in particular 6 to 12 carbon atoms, or may together form a 5- or 6-membered ring containing a nitrogen atom; X iis -CH2-CH2-O-, -CH2-CH(CH3)-O- or -CH(CH3)-CH2-O-, preferably -CH2-CH2-O-; n is a positive integer of 1 to 5, preferably 1 to 4, more preferably 1 to 3, even more preferably 1 or 2, and especially 1. Examples include:

[0042] Preferred individual compounds are dimethylethanolamine, dimethylpropanolamine, diethylethanolamine, diethylpropanolamine, di-n-butylethanolamine, di-n-butylpropanolamine, N-hydroxyethylpyrrolidine, N-hydroxyethylpiperidine and N-hydroxyethylmorpholine.

[0043] Examples of tertiary amines (E) containing two 2-hydroxyethyl or 2-hydroxypropyl groups and one other substituent include those of the general formula (II): [ka] [In the formula, R 4 is a substituent as defined above, preferably a linear or branched, preferably linear, alkyl substituent containing 1 to 18 carbon atoms, preferably 2 to 16, more preferably 4 to 14, especially 6 to 12 carbon atoms; For each X for i=1 to p and 1 to q i is independently selected from the group consisting of -CH2-CH2-O-, -CH2-CH(CH3)-O-, or -CH(CH3)-CH2-O-, preferably -CH2-CH2-O-; and p and q are each independently a positive integer of 1 to 5, preferably 1 to 4, more preferably 1 to 3, even more preferably 1 or 2, especially 1. Examples include:

[0044] Preferred individual compounds are those containing the substituent R 4and bis(2-hydroxyethyl)amine or bis(2-hydroxypropyl)amine containing n-hexylamine, 2-methylpentylamine, n-heptylamine, 2-heptylamine, isoheptylamine, 1-methylhexylamine, n-octylamine, 2-ethylhexylamine, 2-aminooctane, 6-methyl-2-heptylamine, n-nonylamine, isononylamine, n-decylamine, and 2-propylheptylamine as the amine, or a mixture thereof.

[0045] Particularly preferred are bis(2-hydroxyethyl)-substituted n-hexylamines, n-octylamine, 2-ethylhexylamine and n-decylamine (especially preferred are n-octylamine and 2-ethylhexylamine), and in particular bis(2-hydroxyethyl)n-octylamine.

[0046] These compounds are reacted with the corresponding amine R 4 This can be obtained by reacting -NH with alkylene oxides to the desired average statistical degree of alkoxylation, preferably under basic conditions. i is particularly preferred when it is derived from ethylene oxide or propylene oxide, preferably ethylene oxide.

[0047] Examples of tertiary amines (E) containing three 2-hydroxyethyl or 2-hydroxypropyl groups include triethanolamine and tripropanolamine, preferably triethanolamine.

[0048] Preferred amines (E) are dimethylethanolamine, dimethylpropanolamine, diethylethanolamine, di-n-butylethanolamine, N-hydroxyethylmorpholine, bis(2-hydroxyethyl)n-hexylamine, bis(2-hydroxyethyl)n-octylamine, bis(2-hydroxyethyl)2-ethylhexylamine, bis(2-hydroxyethyl)n-decylamine and triethanolamine.

[0049] Carboxylic Acid (F) The carboxylic acid (F) is preferably a monocarboxylic acid (F1) or a dicarboxylic acid (F2). Higher carboxylic acids are possible but less preferred. Preferably, no carboxylic acids with a functionality higher than 2 are present in the coolant according to the invention.

[0050] The carboxylic acid may be aliphatic, alicyclic or aromatic, preferably aliphatic or aromatic, most preferably aliphatic.

[0051] In a preferred embodiment, the coolant according to the invention comprises at least one aliphatic monocarboxylic acid (F1).

[0052] In another preferred embodiment, the coolant according to the invention comprises at least one aliphatic dicarboxylic acid (F2).

[0053] In another preferred embodiment, the coolant according to the invention comprises a mixture of at least one aliphatic monocarboxylic acid (F1) and at least one aliphatic dicarboxylic acid (F2).

[0054] Suitable monocarboxylic acids (F1) may be linear or branched aliphatic, alicyclic or aromatic monocarboxylic acids having up to 20 carbon atoms, preferably 2 to 18, more preferably 5 to 16, even more preferably 5 to 14, most preferably 6 to 12, especially 8 to 10 carbon atoms.

[0055] Branched chain aliphatic monocarboxylic acids are preferred over the corresponding straight chain monocarboxylic acids.

[0056] Useful linear or branched aliphatic or cycloaliphatic monocarboxylic acids (F1) are, for example, propionic acid, pentanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, 2,2-dimethylbutanoic acid, cyclohexylacetic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, decanoic acid, undecanoic acid or dodecanoic acid.

[0057] Suitable aromatic monocarboxylic acids (F1) are, in particular, benzoic acid. Also useful are, for example, C1-C8-alkylbenzoic acids, such as o-, m-, p-methylbenzoic acid or p-tert-butylbenzoic acid, and hydroxyl-containing aromatic monocarboxylic acids, such as o-, m-, or p-hydroxybenzoic acid, o-, m-, or p-(hydroxymethyl)benzoic acid, or halobenzoic acids, such as o-, m-, or p-fluorobenzoic acid.

[0058] Particularly preferred are 2-ethylhexanoic acid and isononanoic acid.

[0059] As used herein, isononanoic acid refers to one or more branched aliphatic carboxylic acids having nine carbon atoms. Embodiments of isononanoic acid used in engine coolant compositions can include 7-methyloctanoic acid (e.g., CAS Nos. 693-19-6 and 26896-18-4), 6,6-dimethylheptanoic acid (e.g., CAS No. 15898-92-7), 3,5,5-trimethylhexanoic acid (e.g., CAS No. 3302-10-1), 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, 2,2,4,4-tetramethylpentanoic acid (e.g., CAS No. 3302-12-3), and combinations thereof. In a preferred embodiment, the isononanoic acid contains, as its major component, greater than 90% of one of 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, and 2,2,4,4-tetramethylpentanoic acid. The remainder of the isononanoic acid may include other 9-carbon carboxylic acid isomers and small amounts of one or more contaminants. In a preferred embodiment, the isononanoic acid contains, as its major component, greater than 90% 3,5,5-trimethylhexanoic acid, and even more preferably, the major component is greater than 95% 3,5,5-trimethylhexanoic acid.

[0060] The dicarboxylic acid (F2) preferred as the carboxylic acid (F) is a linear or branched dicarboxylic acid (F2), preferably a linear aliphatic dicarboxylic acid, more preferably having 5 to 14 carbon atoms, most preferably having 6 to 12 carbon atoms.

[0061] When a dicarboxylic acid is used, examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, alkyl or alkenyl succinic acid, 2-methylbutanedioic acid, 2-ethylpentanedioic acid, 2-n-dodecylbutanedioic acid, 2-n-dodecenylbutanedioic acid, 2-phenylbutanedioic acid, 2-(p-methylphenyl)butanedioic acid, 2,2-dimethylbutanedioic acid, 2,3-dimethylbutanedioic acid; 2,3,4-trimethylpentanedioic acid, 2,2,3-trimethyl 2-ethyl-3-methylbutanedioic acid, maleic acid, fumaric acid, pent-2-enedioic acid, hex-2-enedioic acid; hex-3-enedioic acid; 5-methylhex-2-enedioic acid; 2,3-dimethylpent-2-enedioic acid; 2-methylbut-2-enedioic acid, 2-dodecylbut-2-enedioic acid, phthalic acid, isophthalic acid, terephthalic acid and substituted phthalic acids such as 3-methylbenzene-1,2-dicarboxylic acid; 4-phenylbenzene-1,3-dicarboxylic acid; 2-(1-propenyl)benzene-1,4-dicarboxylic acid, and 3,4-dimethylbenzene-1,2-dicarboxylic acid.

[0062] Among them, aliphatic dicarboxylic acids are preferred, dicarboxylic acids having 6 to 12 carbon atoms are more preferred, and dicarboxylic acids (F2) selected from the group consisting of adipic acid, sebacic acid, azelaic acid and dodecanedioic acid are most preferred.

[0063] In addition to or instead of the carboxylic acids (F1) or (F2), it is possible, but disadvantageous, to use carboxylic acids having a functionality higher than 2, for example tricarboxylic acids.

[0064] When a dicarboxylic or tricarboxylic acid is used, it may be aliphatic, alicyclic or aromatic, preferably aliphatic or aromatic, more preferably aliphatic, having up to 20 carbon atoms, preferably up to 18, more preferably up to 16, even more preferably up to 14, especially up to 12 carbon atoms.

[0065] When tricarboxylic acids are used, examples of tricarboxylic acids include benzenetricarboxylic acid (all isomers) and triazinetriiminocarboxylic acids such as 6,6',6''-(1,3,5-triazine-2,4,6-triyltriimino)trihexanoic acid.

[0066] Silicophosphonate (G) According to the invention, at least one silicophosphonate (G) is used in the coolant.

[0067] Silicophosphonates have the general structure (V) [ka] [In the formula, R 5 is a divalent organic group, preferably a 1,ω-alkylene group having 1 to 6, preferably 1 to 4 carbon atoms, more preferably methylene, 1,2-ethylene, 1,2-propylene, 1,3-propylene or 1,4-butylene, most preferably 1,2-ethylene or 1,3-propylene, especially 1,2-ethylene; R 6 are, independently of one another, hydrogen, C1- to C4-alkyl or hydroxy-C2- to C4-alkyl, preferably hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, 2-hydroxyethyl or 2-hydroxypropyl, more preferably hydrogen, methyl, ethyl or propyl; R 7 is C1- to C4-alkyl] It is of the type.

[0068] Such silicophosphonates may be present as the free phosphonic acid or in the form of their sodium or potassium salts, preferably the sodium or potassium salts, more preferably the sodium salts.

[0069] In a preferred embodiment, at least one silicate (D) and at least one silicophosphonate (G) are applied to the coolant or coolant concentrate as a mixture of components (D) and (G), for example, in a weight ratio (D):(G) of 1:2 to 10:1, preferably 1:1 to 5:1, more preferably 2:1 to 4:1. For better application, such mixtures can be used as formulations in water (B) and / or glycol (A).

[0070] Additional Coolant Additives (H) Additionally, it is possible to add further typical coolant additives to the coolant of the present invention.

[0071] The cooling agent of the present invention may contain, as additional conventional adjuvants, conventional small amounts of antifoaming agents (generally in an amount of 0.003 to 0.008% by weight) and, for reasons of hygiene and safety in case of swallowing, bitter substances (for example of the denatonium benzoate type) and dyes.

[0072] composition Typically, a coolant according to the present invention is composed as follows: (A) at least one glycol: 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight; (B) Water: 10 to 90% by weight, preferably 20 to 80% by weight, more preferably 30 to 70% by weight; (C) at least one azole derivative: 0.01 to 1% by weight, preferably 0.02 to 0.9% by weight, more preferably 0.03 to 0.8% by weight, even more preferably 0.04 to 0.5% by weight, in particular 0.05 to 0.3% by weight; (D) at least one inorganic silicate: 0.001 to 1% by weight, preferably 0.005 to 0.75% by weight, more preferably 0.01 to 0.5% by weight, even more preferably 0.02 to 0.25% by weight, in particular 0.03 to 0.1% by weight; (E) at least one tertiary amine which may be contained if desired: 0 to 1% by weight, preferably 0.01 to 0.9% by weight, more preferably 0.015 to 0.8% by weight, and particularly 0% by weight; (F) at least one carboxylic acid: 2 to 4.5% by weight, preferably 2.2 to 4% by weight, more preferably 2.5 to 3.5% by weight; (G) At least one silicophosphonate: 0.01 to 1% by weight, preferably 0.02 to 0.8% by weight, more preferably 0.03 to 0.6% by weight. (H) At least one optional additional coolant additive: 0 to 0.5 wt. %, preferably 0.01 to 0.4 wt. %, more preferably 0.02 to 0.3 wt. % for each additional coolant additive.

[0073] However, the total of all ingredients always equals 100% by weight.

[0074] In a preferred embodiment of the present invention, no tertiary amine (E) is present in the coolant.

[0075] Another embodiment of the present invention is a coolant concentrate. The coolant is typically obtained from the coolant concentrate by diluting it with water (B). Thus, the coolant concentrate typically contains little or no water (B).

[0076] Typically, a coolant concentrate according to the present invention is composed as follows: (A) at least one glycol: 50 to 99.9% by weight, preferably 60 to 99.8% by weight, more preferably 75 to 99.7% by weight; (B) Water: 0 to 10% by weight, preferably 0 to 8% by weight, more preferably 0 to 5% by weight; (C) at least one azole derivative: 0.02 to 2% by weight, preferably 0.04 to 1.8% by weight, more preferably 0.06 to 1.6% by weight, even more preferably 0.08 to 1%, in particular 0.1 to 0.6% by weight; (D) at least one inorganic silicate: 0.002 to 2% by weight, preferably 0.01 to 1.5% by weight, more preferably 0.02 to 1% by weight, even more preferably 0.04 to 0.5% by weight, in particular 0.06 to 0.2% by weight; (E) at least one tertiary amine which may be contained if desired: 0 to 2% by weight, preferably 0.02 to 1.8% by weight, more preferably 0.03 to 1.6% by weight, in particular 0% by weight; (F) at least one carboxylic acid: 4 to 9% by weight, preferably 4.4 to 8% by weight, more preferably 5 to 7% by weight; (G) at least one silicophosphonate: 0.02 to 2% by weight, preferably 0.04 to 1.6% by weight, more preferably 0.06 to 1.2% by weight; (H) At least one optional additional coolant additive: 0 to 1 wt. %, preferably 0.02 to 0.8 wt. %, more preferably 0.04 to 0.6 wt. % for each additional coolant additive.

[0077] However, the total of all ingredients always equals 100% by weight.

[0078] In a preferred embodiment of the present invention, no tertiary amine (E) is present in the coolant concentrate.

[0079] Another embodiment of the present invention is a refrigerant super concentrate. The refrigerant concentrate is typically obtained by diluting the refrigerant super concentrate with glycol (A), and the refrigerant can be obtained by diluting the refrigerant super concentrate with glycol (A) and water (B), respectively. Thus, the refrigerant concentrate typically contains little or no water (B) and little or no glycol (A).

[0080] Typically, a refrigerant super concentrate according to the present invention is composed as follows: (A) at least one glycol: 60 to 95% by weight, preferably 70 to 90% by weight, more preferably 75 to 85% by weight; (B) Water: 0 to 10% by weight, preferably 0 to 8% by weight, more preferably 0 to 5% by weight; (C) at least one azole derivative: 0.04 to 4% by weight, preferably 0.1 to 3.6% by weight, more preferably 0.2 to 3% by weight, even more preferably 0.3 to 2% by weight, in particular 0.4 to 1.5% by weight; (D) at least one inorganic silicate: 0.005 to 4% by weight, preferably 0.02 to 3% by weight, more preferably 0.05 to 2% by weight, even more preferably 0.1 to 1% by weight, in particular 0.15 to 0.8% by weight; (E) at least one tertiary amine which may be contained if desired: 0 to 4% by weight, preferably 0.1 to 3.5% by weight, more preferably 0.2 to 2.5% by weight, in particular 0% by weight; (F) at least one carboxylic acid: 8 to 18% by weight, preferably 9 to 16% by weight, more preferably 10 to 14% by weight; (G) at least one silicophosphonate: 0.05 to 4% by weight, preferably 0.1 to 3% by weight, more preferably 0.15 to 2.5% by weight; (H) At least one optional additional coolant additive: 0 to 1 wt. %, preferably 0.05 to 1.5 wt. %, more preferably 0.08 to 1.2 wt. % for each additional coolant additive.

[0081] However, the total of all ingredients always equals 100% by weight.

[0082] In a preferred embodiment of the present invention, no tertiary amine (E) is present in the coolant super concentrate.

[0083] Example The following examples illustrate the present invention without, however, limiting it in any way.

[0084] Coolant concentrate compositions were prepared by mixing the ingredients set forth in Table 1 (all amounts are in weight percent unless otherwise indicated). The properties and physical parameters noted in Table 1 were determined as follows: Water, %: DIN 51777 pH (as is): ASTM D 1287

[0085] Exemplary coolant concentrates were formulated as follows, and silicon content was measured by ICP-OES after 25 weeks of storage at room temperature.

[0086] [Table 1]

[0087] It can be readily seen that the silicon content of all samples decreased during the 25-week storage period, but the samples of Examples 1 and 3, which contained a mixture of silicophosphonate and sodium metasilicate, exhibited higher silicon contents after storage than the comparative formulations of Examples 2 and 4, which contained sodium metasilicate in the absence of silicophosphonate.

[0088] The coolant compositions of Examples 1-4 were compared in a corrosion test according to ASTM D 1384 at 88°C. Results (weight change, mg / cm 2 ) are shown in Table 2.

[0089] [Table 2]

[0090] Corrosion tests on aluminum for Comparative Examples 2 and 4 show a slight increase in weight or even material removal, whereas Examples 1 and 3 show a constant weight or a slight increase in weight of the samples, confirming the higher effectiveness of the silicate as a corrosion inhibitor in the presence of the silicophosphonate. Corrosion tests on other metals and alloys show good anticorrosion activity of the formulations according to Examples 1 to 4. Some embodiments are given below. Item 1 A method for improving the storage stability of an inorganic silicate (D) in a coolant or coolant concentrate, wherein the coolant or coolant concentrate contains, in addition to the inorganic silicate (D), a compound of the general structure (V)

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Claims

1. A method for improving the storage stability of an inorganic silicate (D) in a coolant or coolant concentrate, wherein the coolant or coolant concentrate contains, in addition to the inorganic silicate (D), at least one aliphatic carboxylic acid (F) and a compound having the general structure (V): 【Chemistry 1】 [In the formula, R 5 is a divalent organic group; R 6 are, independently of each other, hydrogen, C 1 -~C 4 -Alkyl or hydroxy-C 2 -~C 4 -alkyl; and R 7 is C 1 -~C 4 -alkyl] The method according to claim 1, wherein the silicophosphonate (G) is at least one of the following:

2. Inorganic silicate (D) is orthosilicate (SiO 4 4- ), metasilicate (SiO 3 2- ) and pyrosilicate (Si 2 O 7 6- 2. The method of claim 1, wherein the hydroxybenzoate is selected from the group consisting of:

3. A compound having the general structure (V) for enhancing the storage stability of a coolant or coolant concentrate containing at least one aliphatic carboxylic acid (F) and at least one inorganic silicate (D). 【Chemistry 2】 [In the formula, R 5 is a divalent organic group; R 6 are, independently of each other, hydrogen, C 1 -~C 4 -Alkyl or hydroxy-C 2 -~C 4 -alkyl; and R 7 is C 1 -~C 4 -alkyl] Use of at least one silicophosphonate (G).

4. (A) at least one glycol; (B) water; (C) at least one azole derivative; (D) at least one inorganic silicate; (E) optionally at least one tertiary amine; (F) at least one aliphatic carboxylic acid; (G) General structure (V) 【Transformation 3】 [In the formula, R 5 is a divalent organic group; R 6 are, independently of each other, hydrogen, C 1 -~C 4 -Alkyl or hydroxy-C 2 -~C 4 -alkyl; and R 7 is C 1 -~C 4 -alkyl] at least one silicophosphonate of (H) At least one optional additional coolant additive. A coolant comprising:

5. 5. The coolant of claim 4, wherein the glycol (A) is selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, monopropylene glycol, dipropylene glycol, 1,3-propanediol, higher polyalkylene glycols, alkylene glycol ethers, and glycerol.

6. 6. The coolant according to claim 4 or 5, wherein the azole derivative (C) is selected from the group consisting of benzimidazole, benzotriazole, tolutriazole, hydrogenated tolutriazole, (2-benzothiazylthio)acetic acid and (2-benzothiazylthio)propionic acid.

7. Inorganic silicate (D) is orthosilicate (SiO 4 4- ), metasilicate (SiO 3 2- ) and pyrosilicate (Si 2 O 7 6- 7. The cooling agent according to claim 4, wherein the cooling agent is selected from the group consisting of:

8. A coolant according to any one of claims 4 to 7, wherein the aliphatic carboxylic acid (F) is an aliphatic monocarboxylic acid or an aliphatic dicarboxylic acid or a mixture thereof.

9. A coolant according to any one of claims 4 to 8, wherein the aliphatic carboxylic acid (F) is a linear or branched aliphatic monocarboxylic acid (F1).

10. The coolant of claim 9, wherein the aliphatic monocarboxylic acid (F1) is selected from the group consisting of 2-ethylhexanoic acid and isononanoic acid.

11. A coolant according to any one of claims 4 to 8, wherein the aliphatic carboxylic acid (F) is a linear or branched aliphatic dicarboxylic acid (F2).

12. The coolant of claim 11, wherein the aliphatic dicarboxylic acid (F2) is selected from the group consisting of adipic acid, sebacic acid, azelaic acid and dodecanedioic acid.

13. The method of claim 1, wherein R 5 is selected from the group consisting of methylene, 1,2-ethylene, 1,2-propylene, 1,3-propylene, or 1,4-butylene.

14. The use according to claim 3, wherein R 5 is selected from the group consisting of methylene, 1,2-ethylene, 1,2-propylene, 1,3-propylene, and 1,4-butylene.

15. The coolant of claim 4, wherein R 5 is selected from the group consisting of methylene, 1,2-ethylene, 1,2-propylene, 1,3-propylene, or 1,4-butylene.

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