Heat transfer fluids with low electrical conductivity

Abstract

The present invention relates to a heat transfer fluid composition, such as a concentrated and ready-to-use heat transfer fluid composition comprising a base fluid, a divalent metal cation and an organic phosphoric acid or salt thereof, the heat transfer fluid composition having a conductivity of less than 500 μS / cm at 25° C., the base fluid consisting of water and alcohol, the alcohol being present in an amount ranging from 10 to 99.5 wt. % by weight of the base fluid, and the composition comprising greater than 75 wt. % of the base fluid by total weight of the composition.

Description

Detailed Description of the Invention

[0001] [Field of the Invention]

[0001] The present invention relates to a heat transfer fluid having low electrical conductivity, which is useful in a variety of applications including new energy vehicles, battery electric and fuel cell electric vehicles. The present invention further relates to a method for preparing said heat transfer fluid, as well as methods and uses of said heat transfer fluid.

[0002] [Background technology]

[0002] Heat transfer fluids are widely employed in heat exchange systems associated with internal combustion engines, solar systems, fuel cells, electric motors, generators, electronic devices, battery devices, etc. Heat transfer fluids are generally composed of a base fluid and one or more additives.

[0003]

[0003] Historically, water has been the preferred base fluid from the standpoint of heat transfer properties. In many applications, antifreeze properties are required, in which case a base fluid consisting of water mixed with a freezing point depressant such as an alcohol, glycol or salt is used. The additives present in the heat transfer fluid can be used to obtain various functions such as (further) lowering of the freezing point, improving the heat exchange properties, inhibiting corrosion, etc. Since heat transfer fluids are in continuous contact with metal parts (aluminum alloys, cast iron, steel, copper, brass, solder, etc.), they almost always contain one or more corrosion inhibitors.

[0004]

[0004] The increased development and use of alternative energy technologies, such as battery electric or fuel cell electric vehicles and power plants, which are attractive alternatives to combustion engines due to their relatively low pollutant output, has created a need for new types of heat transfer fluids.

[0005]

[0005] A fuel cell is an electrochemical cell in which stored chemical energy is converted into electrical energy by the controlled oxidation of a fuel. In most applications, several electrochemical cells are stacked in series in a so-called fuel cell stack, making it possible to generate higher voltages. The heat generated by the fuel cell stack can be removed by passing a heat transfer fluid through the channels formed by the bipolar plates.

[0006]

[0006] The potential difference between the positive and negative ends of the fuel cell stack can cause a shunt current to flow through the heat transfer fluid, thus reducing the voltage of the fuel cell. In addition to the detrimental loss of voltage, the shunt current can cause additional problems, such as corrosion of the separator plates near the positive end of the fuel cell stack.

[0007]

[0007] A battery is an electrochemical cell in which stored chemical energy is converted into electrical energy by oxidation-reduction reactions. In most applications, several electrochemical cells are arranged together in series in a so-called battery pack, allowing to generate higher voltages. Heat generated by the battery pack can be removed by passing a heat transfer fluid through a passageway within or outside the battery pack.

[0008] In the event of contact between the heat transfer fluid and the current collectors (tabs) of the battery pack, safety-critical events such as short circuits or electrolysis (resulting in the formation of flammable hydrogen gas) can occur.

[0009]

[0009] In electric machines, such as electric motors, the heat transfer fluid may come into contact with current carrying components, such as copper windings, In such cases, power loss or short circuits may lead to failure of the device.

[0010]

[0010] Thus, heat transfer fluids for use in electrical applications such as batteries and fuel cells must have low electrical conductivity (i.e., high electrical resistivity) and should be able to maintain this throughout the life of the heat transfer fluid.

[0011]

[0011] Most known heat transfer fluids (e.g. coolants) are specially designed for internal combustion engines and are not suitable for use in electrical applications such as fuel cells, batteries, electric machines or power electronics because (i) they have high electrical conductivity or (ii) they become significantly more conductive upon aging, especially at high temperatures. The increase in electrical conductivity upon aging is generally due to the formation of ionic compounds resulting from the degradation of alcohols, especially glycols, often used as base fluids, due to additive degradation, metal corrosion and / or impurities in the cooling circuit.

[0012]

[0012] Accordingly, in recent years there has been increased interest in developing heat transfer fluids suitable for use in electrical applications such as fuel cells, batteries, electric machines or power electronics.

[0013]

[0013] EP 1 485 444 B1 describes a low conductivity aqueous heat transfer fluid for use in fuel cells which contains a water soluble alcoholic antifreeze agent, a triazole, an amine and / or an amine phosphate.

[0014]

[0014] U.S. Patent Application Publication No. 2005 / 0109979 A1 describes a heat transfer fluid for electric vehicles that includes a base and a corrosion inhibitor additive which is an amide compound, an imide compound or an azole compound that inhibits oxidation of the base or blocks ions from leaching into the cooling system, thereby reducing the increase in electrical conductivity of the heat transfer fluid.

[0015]

[0015] EP 1 739 775 B1 describes a heat transfer fluid comprising a base and an anti-corrosion additive, which is a sugar alcohol, that inhibits oxidation of the base and reduces the increase in electrical conductivity.

[0016]

[0016] US Pat. No. 7,201,982 B2 describes low conductivity fuel cell coolant compositions that contain one or more carboxylic acids or salts thereof.

[0017]

[0017] US Patent Application Publication No. 2017 / 009120A1 describes a heat transfer fluid for preventing corrosion in a heat transfer system, comprising H3PO4, a divalent metal cation and a polyelectrolyte polymer.

[0018]

[0018] US Patent Application Publication No. 2014 / 061529 A1 describes nitrite-containing coolant formulations that provide corrosion protection for metals.

[0019]

[0019] Known heat transfer fluids capable of maintaining low electrical conductivity have several drawbacks. They depend, for example, on the presence of additives that may be expensive, toxic or have other undesirable properties. Furthermore, the additives used in the art to maintain low electrical conductivity are often consumed in the process, so large amounts of the additives are required for practical use, which may also affect other properties of the heat transfer fluid in undesirable ways.

[0020]

[0020] Alcohol-based, such as glycol-based, heat transfer fluids have several advantages: for example, they have low freezing points combined with low viscosities and high flash points, and the safety profiles of the different glycols have been extensively studied.

[0021]

[0021] While many metals are suitable for use in heat exchange systems for components such as cooling plates and heat exchangers, aluminum-based materials are often preferred due to their light weight.

[0022]

[0022] Controlled Atmosphere Brazing (CAB) is the preferred technique for manufacturing such aluminum parts due to the advantageous properties of the final product and the relatively uncomplicated manufacturing method. However, a drawback of this technique is that the flux residues left by the CAB process are prone to hydrolysis and dissolution during contact with the heat transfer fluid. Eliminating this problem is not straightforward, as it requires either performing additional cleaning steps to remove the flux residues or using less optimal manufacturing techniques. This therefore means that the compatibility of CAB materials with many heat transfer fluids is not ideal, especially when maintaining low electrical conductivity in the heat transfer fluid is essential.

[0023]

[0023] We have found that it would be particularly desirable to provide an alcohol-based, and particularly a glycol-based, heat transfer fluid that is capable of maintaining low electrical conductivity upon aging in the presence of aluminum. It is a particular object of the present invention to provide a heat transfer fluid that has improved compatibility with heat exchanger elements manufactured by controlled atmosphere brazing (CAB).

[0024] It is a further object of the present invention to provide an improved heat transfer fluid, preferably an alcohol-based heat transfer fluid, suitable for use in electrical systems such as fuel cells, batteries, electric machines or power electronics.

[0025]

[0025] It is still a further object of the present invention to provide a heat transfer fluid, preferably an alcohol-based heat transfer fluid, that has low electrical conductivity and is capable of maintaining low electrical conductivity upon aging, such as aging at high temperatures.

[0026]

[0026] Yet another object of the present invention is to provide a heat transfer fluid, preferably an alcohol-based heat transfer fluid, that requires fewer additives than known heat transfer fluids while maintaining a comparable low conductivity upon aging, such as aging at high temperatures.

[0027] It is a further object of the present invention to provide a heat transfer fluid, preferably glycol-based, that has an extended life compared to known heat transfer fluids.

[0028]

[0028] It is a further object of the present invention to provide a heat transfer fluid that has less toxicity or other improved properties compared to known heat transfer fluids that are capable of maintaining low electrical conductivity.

[0029] [Summary of the Invention]

[0029] The inventors have discovered that one or more of these objectives may be met by using a heat transfer fluid composition comprising a base fluid, a divalent metal cation and an organic phosphoric acid or salt thereof, the heat transfer fluid composition having a conductivity of less than 500 μS / cm at 25° C.

[0030] As shown in the accompanying examples, it has surprisingly been found that the combination of a divalent metal cation and an organic phosphoric acid or salt thereof maintains a low electrical conductivity upon aging at high temperatures. It has further surprisingly been found that the heat transfer fluid composition according to the invention can maintain this low electrical conductivity upon aging at high temperatures in the presence of an aluminum substrate. It has further surprisingly been found that the heat transfer fluid composition according to the invention can maintain this low electrical conductivity upon aging at high temperatures in the presence of an aluminum structure manufactured using controlled atmosphere brazing (CAB).

[0031]

[0031] Based on the present disclosure, one skilled in the art will understand that the heat transfer fluid compositions of the present invention are suitable for use in electrical applications that require fewer additives (especially antioxidants) and / or may maintain lower electrical conductivity upon long-term aging than comparable heat transfer fluid compositions known in the art.

[0032]

[0032] Thus, in a first aspect, the present invention provides heat transfer fluid compositions comprising a base fluid, a divalent metal cation and an organophosphoric acid or salt thereof, the heat transfer fluid compositions having a conductivity of less than 500 μS / cm at 25° C., the base fluid consisting of water and alcohol, the alcohol being present in an amount ranging from 10 to 99.5% by weight of the base fluid, and the composition comprising greater than 75% by weight of the total composition. As shown herein, these heat transfer fluid compositions are capable of maintaining low electrical conductivity, such as upon aging at high temperatures in the presence of a CAB aluminum substrate, using the test procedures described in the Experimental Section.

[0033] In a preferred embodiment, the heat transfer fluid compositions of the present invention are provided in the form of the ready-to-use compositions described herein.

[0034] In a second aspect, the present invention provides a method for preparing the heat transfer fluid compositions and ready-to-use compositions described herein, comprising the steps of: (i) providing a base fluid; (ii) providing an organophosphoric acid or a salt thereof; (iii) providing a salt of a divalent metal cation; (iv) optionally providing one or more further additives; (v) combining the base fluid of step (i) with the organophosphoric acid or salt thereof of step (ii), the salt of a divalent metal cation of step (iii) and optionally one or more further additives of step (iv) to obtain a composition; The present invention provides a method comprising:

[0035]

[0035] In a third aspect, the present invention provides the use of a heat transfer fluid composition or a ready-to-use composition defined in the present specification as a heat transfer fluid having electrical conductivity inhibiting properties and / or corrosion inhibiting properties.

[0036]

[0036] In a fourth aspect, the present invention provides the use of a heat transfer fluid composition or ready-to-use composition as defined herein to inhibit dissolution of fluoride, aluminum and potassium ions from a brazing flux of an aluminum structure manufactured via controlled atmosphere brazing (CAB) into said composition and / or to maintain low electrical conductivity in an electrical system comprising said composition and an aluminum structure manufactured via controlled atmosphere brazing (CAB).

[0037] [Detailed Description]

[0037] A first aspect of the present invention relates to a heat transfer fluid composition comprising a base fluid, a divalent metal cation and an organic phosphoric acid or salt thereof, the heat transfer fluid composition having a conductivity of less than 500 μS / cm at 25°C, the base fluid consisting of water and alcohol, the alcohol being present in an amount in the range of 10 to 99.5 wt% by weight of the base fluid, and the composition comprising greater than 75 wt% of the base fluid by total weight of the composition.

[0038]

[0038] The heat transfer fluid composition preferably has a conductivity at 25°C of less than 350 μS / cm, more preferably less than 250 μS / cm, even more preferably less than 225 μS / cm, still more preferably less than 200 μS / cm, even more preferably less than 175 μS / cm, even more preferably less than 150 μS / cm, for example less than 100 μS / cm or less than 50 μS / cm.

[0039]

[0039] In a preferred embodiment, the heat transfer fluid composition has a conductivity at 25°C of 5 μS / cm to 500 μS / cm, for example 15 μS / cm to 400 μS / cm, 30 μS / cm to 300 μS / cm, 40 μS / cm to 250 μS / cm, 45 μS / cm to 225 μS / cm, 50 μS / cm to 225 μS / cm, 55 μS / cm to 200 μS / cm, 60 μS / cm to 175 μS / cm or 65 μS / cm to 150 μS / cm.

[0040]

[0040] As will be understood by those skilled in the art, the fact that the heat transfer fluid compositions have a conductivity of less than 500 μS / cm at 25° C., or in preferred embodiments less than this, relates not only to ``fresh'' heat transfer fluid compositions, but also to heat transfer fluid compositions that have been aged at high temperatures, preferably using the test procedures described in the experimental section.

[0041] [Base fluid]

[0041] According to the present invention, the base fluid is composed of water and an alcohol. In a preferred embodiment, the alcohol is selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, monopropylene glycol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, hexapropylene glycol, methanol, ethanol, propanol, butanol, tetrahydrofurfuryl, ethoxylated furfuryl, dimethyl ether of glycerol, sorbitol, 1,2,6-hexanetriol, trimethylolpropane, methoxyethanol, glycerol, and mixtures thereof, more preferably from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol, glycerol, and mixtures thereof.

[0042]

[0042] As used herein, "monoethylene glycol" shall be construed to mean "ethane-1,2-diol", and is interchangeably referred to as "MEG."

[0043]

[0043] As used herein, "monopropylene glycol" shall be construed to mean "propane-1,2-diol" and is interchangeably referred to as "MPG."

[0044]

[0044] As used herein, the term "glycerol" means "propane-1,2,3 triol" and is synonymous with glycerin. In a preferred embodiment of the invention, the base fluid comprises water, monoethylene glycol, monopropylene glycol, 1,3-propanediol, glycerol, or mixtures thereof.

[0045] The base fluid comprises water and an alcohol, the alcohol being present in an amount of 10-99.5% by weight, preferably 10-80% by weight, more preferably 30-70% by weight, by weight of the base fluid. In a particular embodiment, the alcohol is present in an amount ranging from 33-60% by weight of the base fluid.

[0046] In some embodiments, the base fluid comprises greater than 50% by weight water, preferably greater than 70% by weight, and more preferably greater than 85% by weight water, by weight of the base fluid.

[0047] In some embodiments, the base fluid comprises greater than 50% by weight, preferably greater than 70% by weight, more preferably greater than 85% by weight, and most preferably greater than 95% by weight monoethylene glycol, by weight of the base fluid.

[0048] In some embodiments, the base fluid comprises greater than 50% by weight, preferably greater than 70% by weight, more preferably greater than 85% by weight, and most preferably greater than 95% by weight, monopropylene glycol by weight of the base fluid.

[0049] In some embodiments, the base fluid comprises greater than 50% by weight 1,3-propanediol, preferably greater than 70% by weight 1,3-propanediol, more preferably greater than 85% by weight, and most preferably greater than 95% by weight 1,3-propanediol, by weight of the base fluid.

[0050]

[0050] In some embodiments, the base fluid comprises greater than 50% by weight glycerol, preferably greater than 70% by weight glycerol, more preferably greater than 85% by weight, and most preferably greater than 95% by weight glycerol, by weight of the base fluid.

[0051]

[0051] In a preferred embodiment, the heat transfer fluid composition comprises more than 78 wt. % base fluid, more preferably more than 85 wt. %, even more preferably more than 90 wt. %, and still more preferably more than 95 wt. % or more than 96 wt. %, based on the total weight of the heat transfer fluid composition.

[0052]

[0052] As understood by those skilled in the art, the base fluid is usually added to the heat transfer fluid composition in "amount". In some embodiments, the heat transfer fluid composition comprises less than 99.9 wt% of the base fluid, such as less than 99.8 wt%, less than 99.5 wt%, or less than 99 wt%, less than 98 wt%, less than 97 wt%, less than 96 wt%, less than 95 wt%, less than 94 wt%, less than 93 wt%, less than 92 wt%, less than 91 wt%, less than 90 wt%, less than 89 wt%, less than 88 wt%, less than 87 wt%, less than 86 wt%, less than 85 wt%, less than 84 wt%, less than 83 wt%, less than 82 wt%, or less than 81 wt% of the base fluid by the total weight of the heat transfer fluid composition.

[0053] In preferred embodiments, the heat transfer fluid composition comprises less than 99.9%, less than 99.5%, less than 99%, less than 98% or less than 97% by weight of the base fluid by total weight of the heat transfer fluid composition.

[0054] [Organophosphates] According to the present invention, the compositions described herein comprise an organic phosphoric acid or a salt thereof. The compositions may also comprise a mixture of different organic phosphoric acids or salts thereof. Whenever the terms "organophosphoric acid", "organophosphonic acid" or "organophosphinic acid" are used, they should be read as "and salts thereof" unless otherwise specified.

[0055] Suitable cations in the salts of organic phosphoric acids, organic phosphonic acids and organic phosphinic acids are selected from the group consisting of alkali metals, alkaline earth metals, ammonium and protonated amines, preferably selected from the group consisting of lithium, potassium, sodium, magnesium, calcium, strontium, ammonium and protonated amines. As used herein, the term "protonated amine" refers to a quaternary ammonium cation (NR4 + , R is an alkyl or aryl group) and primary, secondary and tertiary ammonium cations. Non-limiting examples of protonated amines are protonated ethoxylated fatty amines and amine ethoxylates such as Genamin CH020, Genamin C200, Genamin 3910, Genamin Gluco 50, the Jeffamine range and the Noramox range.

[0056]

[0056] As used herein, the term "organophosphate" should be taken to mean a compound containing at least one phosphorus atom double-bonded to an oxygen atom (P=O) and at least one organic moiety containing at least one hydroxyl group as a functional group.

[0057]

[0057] As used herein, the term "alkyl chain" should be construed to include both straight and branched chains, the chains being preferably substituted with one or more of hydroxyl groups, amine groups, phosphonic acid groups or salts thereof, and carboxylic acid groups or salts thereof, and the chains may contain one or more of nitrogen, oxygen, and sulfur atoms in their backbones, except at the position of the backbone that is bonded to the phosphorus atom. The alkyl chains preferably contain 2 to 25 carbon atoms, more preferably 2 to 8 carbon atoms.

[0058]

[0058] As used herein, the term "alkoxy chain" should be interpreted as including both straight and branched alkyl chains attached to the phosphorus atom via an oxygen atom, the chain being preferably substituted with one or more of hydroxyl groups, amine groups, phosphonic acid groups or salts thereof and carboxylic acid groups or salts thereof, and the chain may include one or more of nitrogen, oxygen and sulfur atoms in its backbone. The alkoxy chain preferably contains 2 to 25 carbon atoms, more preferably 2 to 8 carbon atoms.

[0059]

[0059] As used herein, the term "aryl group" should be taken to include aryl groups such as phenyl or naphthyl groups preferably substituted with one or more of a hydroxyl group, an amine group, a phosphonic acid group or a salt thereof, and a carboxylic acid group or a salt thereof. The aryl group preferably contains from 6 to 10 carbon atoms.

[0060]

[0060] As used herein, the term "aryloxy group" should be interpreted to include aryl groups such as phenyl or naphthyl groups attached to a phosphorus atom through an oxygen atom and preferably substituted with one or more of a hydroxyl group, an amine group, a phosphonic acid group or a salt thereof, and a carboxylic acid group or a salt thereof. The aryloxy group preferably contains from 6 to 10 carbon atoms.

[0061]

[0061] In one embodiment, the organic phosphoric acid or salt thereof has a molecular weight of less than 10,000 g / mol, preferably less than 5,000 g / mol, more preferably less than 2,500 g / mol, even more preferably less than 1,000 g / mol, for example, from 90 to 750 g / mol or from 250 to 450 g / mol.

[0062] In one embodiment, the organophosphate has formula (I): [ka] (wherein R1 is an alkoxy chain, a hydroxyl group, an alkyl chain, an aryloxy group, or an aryl group, and R2 is an alkyl chain or an aryl group). In a preferred embodiment, the alkoxy chain, alkyl chain, aryloxy group and / or aryl group in the organophosphoric acid according to formula (I) are independently substituted with one or more of a hydroxyl group, an amine group, a phosphonic acid group or a salt thereof and a carboxylic acid group or a salt thereof.

[0063]

[0063] In a preferred embodiment, the organophosphoric acid according to formula (I) is either an organophosphonic acid or an organophosphinic acid, where in the case of the organophosphonic acids, R1 is either an alkoxy chain, an aryloxy group or a hydroxyl group, and R2 is an alkyl chain or an aryl group, and in the case of the organophosphinic acids, both R1 and R2 are independently selected from alkyl chains and aryl groups.

[0064]

[0064] As used herein, the term "organophosphonic acid" includes an organic moiety R2 and a group R1, which can be either an organic moiety or hydrogen, and the phosphorus atom is -It is double bonded to an oxygen atom (P=O), Contains a hydroxyl group as a functional group, and · 1 bond to a carbon atom (PC), It should be understood to mean a compound according to the following general structure (A):

[0065] As used herein, the term "organophosphinic acid" refers to a compound that contains at least two organic moieties, R1 and R2, and in which the phosphorus atom is -It is double bonded to an oxygen atom (P=O), Contains a hydroxyl group as a functional group, and · 2 bonds to a carbon atom (PC), It should be understood to mean a compound according to the following general structure (B): [ka]

[0066]

[0066] In one embodiment, the organophosphoric acid or salt thereof is an organophosphonic acid according to the general structure (A), wherein R1 is either hydrogen or an alkyl chain and R2 is an alkyl chain, wherein the one or more alkyl chains independently contain from 2 to 8 carbon atoms and are optionally independently substituted with one or more of a hydroxyl group, an amine group, a phosphonic acid group or salt thereof, and a carboxylic acid group or salt thereof, preferably substituted with one or more carboxylic acid groups or salts thereof.

[0067] In one embodiment, the organophosphoric acid is an organophosphonic acid according to general structure (A) having a molecular weight of less than 10,000 g / mol, preferably less than 5,000 g / mol, more preferably less than 2,500 g / mol, even more preferably less than 1,000 g / mol, for example from 90 to 750 g / mol or from 250 to 450 g / mol.

[0068]

[0068] In one embodiment, the organophosphoric acid is an organophosphinic acid according to general structure (B), where both R1 and R2 are alkyl chains independently containing from 2 to 8 carbon atoms and optionally independently substituted with one or more of a hydroxyl group, an amine group, a phosphonic acid group or a salt thereof, and a carboxylic acid group or a salt thereof, preferably substituted with one or more carboxylic acid groups or a salt thereof.

[0069] In one embodiment, the organic phosphoric acid or salt thereof is an organic phosphinic acid or salt thereof according to general structure (B) having a molecular weight of less than 10,000 g / mol, preferably less than 5,000 g / mol, more preferably less than 2,500 g / mol, even more preferably less than 1,000 g / mol, for example from 90 to 750 g / mol or from 250 to 450 g / mol.

[0070] In one embodiment, the organophosphate has the following structural formula (C): [ka] (wherein n=1 to 10, preferably n=1 to 5, and alkyl C1 to C10 is linear or branched alkyl). The acids are either organophosphonic acids or organophosphinic acids according to

[0071] In one embodiment, the organophosphate has the following formula (D): [ka] (In the formula, n=1 to 10, m=1 to 5, and alkyl C1 to C10 is a linear or branched alkyl.) It is an organic phosphonic acid based on

[0072] In a preferred embodiment, the organophosphoric acid is an organophosphonic acid selected from the group consisting of 2-phosphonobutane-1,2,4-tricarboxylic acid (2-PBTC), 2-hydroxyphosphonocarboxylic acid (HPAA), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), 2-phosphonobutane-1,2,4-tricarboxylic acid, 2-phosphonobutane-1,2,3,4-tetracarboxylic acid, 2-phosphonoethane-1,2-dicarboxylic acid, 2-carboxyethylphosphonic acid (CEPA), and combinations thereof.

[0073]

[0073] In a preferred embodiment, the organic phosphoric acid is a combination of two or more organic phosphonic acids according to the following formula (II) (wherein n = 1 to 20), preferably a sodium salt of a combination of two or more organic phosphonic acids according to formula (II) (wherein n = 1 to 20), more preferably a sodium salt of a combination of two or more organic phosphonic acids according to formula (II) (wherein n = 1 to 6). [ka]

[0074] In a highly preferred embodiment, the organophosphate is 2-phosphonobutane-1,2,4-tricarboxylic acid (2-PBTC).

[0075] In one embodiment, the organophosphate has the following formula (E): [ka] (In the formula, n=1 to 10, m=1 to 5, and alkyl C1 to C10 is a linear or branched alkyl.) It is an organic phosphinic acid based on

[0076] In a highly preferred embodiment, the organophosphoric acid is the organophosphinic acid 2,2'-(hydroxyphosphoryl)disuccinic acid.

[0077] In one embodiment, the organophosphate has the formula (F): [ka] It is an organic phosphonic acid based on

[0078] In a preferred embodiment, the organophosphoric acid is an organophosphonic acid selected from the group consisting of diethylenetriaminepenta(methylenephosphonic acid) (DTPMP), aminotris(methylenephosphonic acid) (ATMP), hydroxyethylamino-di(methylenephosphonic acid) (HEMPA), ethylenediaminetetra(methylenephosphonic acid) (EDTMP), tetramethylenediaminetetra(methylenephosphonic acid) (TDTMP), hexamethylenediaminetetra(methylenephosphonic acid) (HDTMP), diethylenetriaminepenta(methylenephosphonic acid) (DTPMP), and combinations thereof.

[0079]

[0079] In one embodiment, the organic phosphoric acid or salt thereof is present in the heat transfer fluid composition in an amount in the range of 0.0001 to 0.1 wt %, preferably in the range of 0.0005 to 0.05 wt %, and more preferably in the range of 0.001 to 0.01 wt %, by total weight.

[0080] [Divalent metal cations] In accordance with the present invention, the heat transfer fluid compositions described herein include a divalent metal cation, such as a divalent calcium, magnesium, strontium, manganese, zinc, or copper cation.

[0081] In a preferred embodiment, the divalent metal cation is selected from the group of alkaline earth metals and combinations thereof, more preferably selected from the group consisting of divalent calcium, magnesium and strontium cations and combinations thereof, and most preferably the divalent metal cation is a divalent strontium cation.

[0082] In one embodiment, the divalent metal cation is produced by dissolving the corresponding metal salt. In a preferred embodiment, this is the chloride, bromate, fluoride, iodide, chlorate, borate, nitrate, nitrite, sulfate, sulfite, phosphate, phosphite, hypophosphite, molybdate, selenate, tungstate, silicate, carbonate, acetate, citrate or lactate of the divalent metal cation. In a more preferred embodiment, this is the nitrate, sulfate or acetate of the divalent metal cation. Thus, in one embodiment, the heat transfer fluid compositions described herein further comprise an anion selected from the group consisting of chloride, bromate, fluoride, iodide, chlorate, borate, nitrate, nitrite, sulfate, sulfite, phosphate, phosphite, hypophosphite, molybdate, selenate, tungstate, silicate, carbonate, acetate, citrate, lactate, and combinations thereof, more preferably an anion selected from the group consisting of nitrate, sulfate, acetate, and combinations thereof.

[0083]

[0083] In one embodiment, the divalent metal cation is present in the heat transfer fluid composition in an amount in the range of 0.0001 to 0.1 wt %, preferably in the range of 0.0005 to 0.05 wt %, and more preferably in the range of 0.001 to 0.01 wt %, based on the total weight of the heat transfer fluid composition.

[0084]

[0084] In certain embodiments, the amount of divalent metal cation in the heat transfer fluid composition is controlled so that the molar ratio of divalent metal cation to organophosphate is within the range of 0.01 to 100, preferably within the range of 0.05 to 50, and more preferably within the range of 0.1 to 10.

[0085] [conductivity]

[0085] In an embodiment, there is provided a heat transfer fluid composition as described herein having a conductivity as described elsewhere in this specification, as measured in accordance with ASTM D1125 using a Mettler-Toledo SevenExcellence Cond meter S700 equipped with an InLab 741-ISM conductivity probe.

[0086]

[0086] In an embodiment, the heat transfer fluid composition has a conductivity at 25°C of less than 350 μS / cm, preferably less than 250 μS / cm, more preferably less than 200 μS / cm, even more preferably less than 175 μS / cm, still more preferably less than 150 μS / cm, for example less than 100 μS / cm or less than 50 μS / cm.

[0087]

[0087] In some embodiments, the heat transfer fluid composition has a conductivity at 25°C of 5 μS / cm to 500 μS / cm, 5 μS / cm to 250 μS / cm, 5 μS / cm to 200 μS / cm, 5 μS / cm to 150 μS / cm, 5 μS / cm to 100 μS / cm, 10 μS / cm to 100 μS / cm, 15 μS / cm to 100 μS / cm, 20 μS / cm to 100 μS / cm, 25 μS / cm to 100 μS / cm, 30 μS / cm to 100 μS / cm, 35 μS / cm to 100 μS / cm, 40 μS / cm to 100 μS / cm, 45 μS / cm to 100 μS / cm or 50 μS / cm to 100 μS / cm.

[0088]

[0088] In some embodiments, the heat transfer fluid composition has a conductivity at 25°C of 10μS / cm to 500μS / cm, 10μS / cm to 250μS / cm, 10μS / cm to 200μS / cm, 25μS / cm to 200μS / cm, or 25μS / cm to 150μS / cm.

[0089]

[0089] In some embodiments, the heat transfer fluid composition has a conductivity at 25°C of less than 500 μS / cm, preferably less than 350 μS / cm, more preferably less than 250 μS / cm, even more preferably less than 225 μS / cm, still more preferably less than 175 μS / cm, even more preferably less than 150 μS / cm, for example less than 100 μS / cm or less than 50 μS / cm, after aging at 90°C for 7 days, preferably in the presence of aluminum, more preferably in the presence of an aluminum structure manufactured via controlled atmosphere brazing (CAB), using the test procedures described in the experimental section.

[0090] In some embodiments, there is provided a heat transfer fluid composition as described herein, which, after aging for 7 days at 90° C. in the presence of an aluminum structure produced via Controlled Atmosphere Brazing (CAB), using the test procedures described in the Experimental Section, has a concentration of fluoride dissolved from the CAB flux less than 200 ppm, preferably less than 100 ppm, more preferably less than 50 ppm, even more preferably less than 25 ppm, based on the total weight of the heat transfer fluid composition, and / or a concentration of aluminum dissolved from the CAB flux less than 100 ppm, more preferably less than 50 ppm, even more preferably less than 25 ppm, even more preferably less than 10 ppm, and / or a concentration of potassium dissolved from the CAB flux less than 150 ppm, more preferably less than 100 ppm, even more preferably less than 75 ppm, even more preferably less than 50 ppm, wherein the concentrations of dissolved aluminum and dissolved potassium are determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and the concentration of fluoride is determined by Ion Chromatography (IC).

[0091] In a preferred embodiment, there is provided a heat transfer fluid composition as described herein, wherein after aging for 7 days at 90° C. in the presence of an aluminum structure fabricated via Controlled Atmosphere Brazing (CAB), using the test procedures described in the Experimental Section, the concentration of fluoride dissolved from the CAB flux is less than 200 ppm, preferably less than 100 ppm, more preferably less than 50 ppm, even more preferably less than 25 ppm, based on the total weight of the heat transfer fluid composition; the concentration of aluminum dissolved from the CAB flux is less than 100 ppm, more preferably less than 50 ppm, even more preferably less than 25 ppm, even more preferably less than 10 ppm; and the concentration of potassium dissolved from the CAB flux is less than 150 ppm, more preferably less than 100 ppm, even more preferably less than 75 ppm, even more preferably less than 50 ppm, the concentrations of dissolved aluminum and dissolved potassium being determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and the concentration of fluoride being determined by Ion Chromatography (IC).

[0092] [Corrosion inhibition]

[0092] As described throughout this specification, the heat transfer fluid compositions of the present invention exhibit the electrical conductivity characteristics described herein without significantly corroding metals, preferably copper, brass, solder coated brass, steel, cast iron and aluminum, more preferably aluminum.

[0093] The corrosion inhibition properties of the heat transfer fluid compositions described herein were tested by a Glassware Corrosion Test (per ASTM D1384) and a High Temperature Surface Corrosion Test (per ASTM D4340), the results of which are included in the Experimental Section.

[0094] [Further additives]

[0094] As will be understood by those skilled in the art, based on the teachings presented herein, the heat transfer fluid composition according to the present invention may contain one or more further additives as is conventional in the art. It is within the routine ability of the skilled artisan to determine to what extent a particular additive can be added so that the conductivity of the resulting composition is in accordance with the present invention. As will be understood by those skilled in the art, non-ionic further additives are preferred. The heat transfer fluid composition comprises clearly defined amounts of water, alcohol, divalent metal cations and organic phosphoric acid or salts thereof. Thus, the one or more further additives are different from water, alcohol, divalent metal cations and organic phosphoric acid or salts thereof.

[0095] In a particular embodiment, the heat transfer fluid composition comprises one or more further additives, preferably one or more further additives selected from the group consisting of corrosion inhibitors, liquid dielectrics, antioxidants, antiwear agents, buffers, detergents, antifoam agents, bittering agents and dyes. These can be either inorganic compounds not containing carbon-hydrogen bonds or organic compounds containing carbon-hydrogen bonds. In a preferred embodiment, the heat transfer fluid composition further comprises one or more of said further additives in an amount in the range of 0.0001-20% by weight, preferably 0.005-15% by weight, more preferably 0.025-10% by weight by the total weight of the heat transfer fluid composition.

[0096]

[0096] In a preferred embodiment, the heat transfer fluid composition comprises as further component one or more corrosion inhibitors, preferably selected from the group consisting of silicates, phosphates, organic acids, thiazoles, triazoles, molybdates, nitrates and amines, more preferably selected from the group consisting of organic acids, triazoles and amines.

[0097] In some embodiments, the heat transfer fluid composition further comprises one or more inorganic corrosion inhibitors. As will be appreciated by those skilled in the art, high concentrations of inorganic compounds, especially inorganic compounds in salt form, can increase the electrical conductivity of the heat transfer fluid composition, making it unsuitable for use in fuel cells, resulting in a drop in the fuel cell voltage and corrosion of the separator plates.

[0098]

[0098] In some embodiments, one or more inorganic corrosion inhibitors are present in the heat transfer fluid composition in an amount of less than 100 ppm, preferably less than 75 ppm, more preferably less than 50 ppm, even more preferably less than 25 ppm, and most preferably less than 10 ppm by total weight of the heat transfer fluid composition, provided that the electrical conductivity of the composition at 25°C is less than 500 μS / cm.

[0099]

[0099] In some embodiments, one or more inorganic corrosion inhibitors are present in the heat transfer fluid composition in an amount greater than 1 ppm, greater than 3 ppm, or greater than 5 ppm by total weight of the heat transfer fluid composition, provided that the electrical conductivity of the composition at 25°C is less than 500 μS / cm.

[0100]

[0100] In some embodiments, the heat transfer fluid composition further comprises one or more inorganic corrosion inhibitors in an amount of 0.0001 to 10 wt %, preferably 0.005 to 5 wt %, and more preferably 0.025 to 3 wt %, by total weight of the heat transfer fluid composition, provided that the conductivity of the composition at 25°C is less than 500 μS / cm.

[0101]

[0101] In some embodiments, the heat transfer fluid composition includes one or more inorganic corrosion inhibitors selected from the group consisting of silicates, molybdates, nitrates, nitrites, borates, tungstates, sulfates, sulfites, carbonates, phosphonates, selenates and phosphates.

[0102] In a preferred embodiment, the heat transfer fluid composition further comprises one or more further organic additives selected from the group consisting of thiazoles, triazoles, polyolefins, polyalkylene oxides, silicon oils, silicate esters (e.g., Si(OR)4, where R is a C1-C4 alkyl group), mineral oils, monocarboxylic acids, dicarboxylic acids, tricarboxylic acids and amines. In a preferred embodiment, the heat transfer fluid composition further comprises one or more of said additives in an amount in the range of 0.0001-20 wt.%, preferably 0.005-15 wt.%, more preferably 0.025-10 wt.% by weight of the total heat transfer fluid composition.

[0103] In a preferred embodiment, the heat transfer fluid composition comprises as a further additive a corrosion inhibitor which is a thiazole or triazole, preferably an aromatic triazole or thiazole. In a preferred embodiment, the heat transfer fluid composition comprises as a further additive one or more triazoles selected from the group consisting of tolyltriazole and benzotriazole.

[0104]

[0104] In some embodiments, the heat transfer fluid composition comprises, as a further additive, a triazole or thiazole, preferably tolyltriazole or benzotriazole, in an amount of more than 0.001 wt. %, preferably more than 0.005 wt. %, more preferably more than 0.01 wt. % and / or less than 5 wt. %, preferably less than 1 wt. %, preferably less than 0.1 wt. %, based on the total weight of the heat transfer fluid composition.

[0105]

[0105] In some embodiments, the heat transfer fluid composition comprises an antifoaming agent as a further additive. Preferably, the antifoaming agent is selected from the group consisting of polyalkylene oxides, silicon polymers (such as 3D silicon polymers), silicon oils, and combinations thereof.

[0106]

[0106] In some embodiments, the heat transfer fluid composition comprises, as a further additive, more than 0.001 wt. %, preferably more than 0.005 wt. %, preferably more than 0.01 wt. % and / or less than 10 wt. %, preferably less than 5 wt. %, preferably less than 3 wt. % of an antifoaming agent by the total weight of the heat transfer fluid composition.

[0107]

[0107] In some embodiments, the heat transfer fluid composition includes as an additional additive a corrosion inhibitor selected from the group consisting of aromatic carboxylates, aliphatic monocarboxylates, aliphatic dicarboxylates, aliphatic tricarboxylates, polymeric corrosion inhibitors, and combinations thereof.

[0108] In some embodiments, the heat transfer fluid composition may further comprise, as an additive, an aliphatic monocarboxylate, preferably C4-C 12 The heat transfer fluid composition comprises an aliphatic monocarboxylate selected from the group consisting of aliphatic monocarboxylates in an amount greater than 50 ppm, preferably greater than 100 ppm, preferably greater than 500 ppm and / or less than 5000 ppm, preferably less than 2500 ppm, preferably less than 1000 ppm by total weight of the heat transfer fluid composition.

[0109] In some embodiments, the heat transfer fluid composition may further comprise, as an additive, an aliphatic dicarboxylate, preferably C6-C 16 The heat transfer fluid composition comprises an aliphatic dicarboxylate selected from the group consisting of aliphatic dicarboxylates in an amount of more than 50 ppm, preferably more than 100 ppm, preferably more than 500 ppm and / or less than 5000 ppm, preferably less than 2500 ppm, preferably less than 1000 ppm by total weight of the heat transfer fluid composition.

[0110] In some embodiments, the heat transfer fluid composition may further comprise, as an additive, an aliphatic tricarboxylate, preferably C7-C 18The heat transfer fluid composition comprises an aliphatic tricarboxylate selected from the group consisting of aliphatic tricarboxylates in an amount greater than 50 ppm, preferably greater than 100 ppm, preferably greater than 500 ppm and / or less than 5000 ppm, preferably less than 2500 ppm, preferably less than 1000 ppm by total weight of the heat transfer fluid composition.

[0111]

[0111] In some embodiments, the heat transfer fluid composition comprises as a further additive an aromatic carboxylate, preferably selected from the group consisting of benzoate, benzene-1,2-dicarboxylate, benzene-1,2,3-tricarboxylate, benzene-1,2,4-tricarboxylate, benzene-1,4-dicarboxylate and combinations thereof, in an amount of more than 50 ppm, preferably more than 100 ppm, preferably more than 500 ppm and / or less than 5000 ppm, preferably less than 2500 ppm, preferably less than 1000 ppm by total weight of the heat transfer fluid composition.

[0112] In some embodiments, the heat transfer fluid composition comprises as a further additive an amine as a corrosion inhibitor or neutralizing base. Preferably, the amine is selected from the group consisting of ethoxylated fatty amines, amine ethoxylates, ethanolamine, diethanolamine, triethanolamine, morpholine, benzylamine, cyclohexylamine, dicyclohexylamine, hexylamine, AMP (2-amino-2-methyl-l-propanol or isobutanolamine), DEAE (diethylethanolamine), DEHA (diethylhydroxylamine), DMAE (2-dimethylaminoethanol), DMAP (dimethylamino-2-propanol), MOPA (3-methoxypropylamine) and combinations thereof.

[0113]

[0113] In some embodiments, the heat transfer fluid composition comprises, as a further additive, an amine in an amount of more than 0.001 wt. %, preferably more than 0.005 wt. %, preferably more than 0.01 wt. % and / or less than 10 wt. %, preferably less than 5 wt. %, preferably less than 3 wt. %, based on the total weight of the heat transfer fluid composition.

[0114] In some embodiments, the heat transfer fluid composition includes an antioxidant as a further additive. Preferably, the antioxidant is selected from the group consisting of phenols such as 2,6-di-t-butylmethylphenol and 4,4'-methylene-bis(2,6-di-t-butylphenol), aromatic amines such as p,p-dioctylphenylamine, monooctyldiphenylamine, phenothiazine, 3,7-dioctylphenothiazine, phenyl-1-naphthylamine, phenyl-2-naphthylamine, alkylphenyl-1-naphthalamine and alkyl-phenyl-2-naphthalamine, and sulfur-containing compounds and combinations thereof.

[0115]

[0115] In some embodiments, the heat transfer fluid composition comprises, as a further additive, more than 0.001 wt. %, preferably more than 0.005 wt. %, preferably more than 0.01 wt. % and / or less than 10 wt. %, preferably less than 5 wt. %, preferably less than 3 wt. % of an antioxidant based on the total weight of the heat transfer fluid composition.

[0116] In some embodiments, the heat transfer fluid composition includes an anti-wear agent as an additional additive.

[0117]

[0117] In some embodiments, the heat transfer fluid composition comprises, as a further additive, more than 0.001 wt. %, preferably more than 0.005 wt. %, preferably more than 0.01 wt. % and / or less than 10 wt. %, preferably less than 5 wt. %, preferably less than 3 wt. % of an anti-wear agent by the total weight of the heat transfer fluid composition.

[0118] In some embodiments, the heat transfer fluid composition includes one or more surfactants as further additives. In a preferred embodiment, the one or more surfactants are selected from the group consisting of non-ionic surfactants, such as: fatty acid esters, for example sorbitan fatty acid esters, Polyalkylene glycols, Polyalkylene glycol esters, Copolymers and block copolymers of ethylene oxide and propylene oxide, Polyoxyalkylene derivatives of sorbitan fatty acid esters, and Alkoxylated alcohol ethers and one or more nonionic surfactants selected from the group consisting of:

[0119]

[0119] In some embodiments, the heat transfer fluid composition comprises one or more surfactants in an amount greater than 0.001 wt.%, preferably greater than 0.005 wt.%, preferably greater than 0.01 wt.%, and / or less than 10 wt.%, preferably less than 5 wt.%, preferably less than 3 wt.%, based on the total weight of the heat transfer fluid composition.

[0120]

[0120] In certain embodiments of the present invention, the heat transfer fluid composition comprises a dielectric liquid as a further additive. Preferred dielectric liquids are mineral oil, silicone oil and mixtures thereof.

[0121]

[0121] In certain embodiments, the heat transfer fluid composition comprises more than 0.0001 wt.%, preferably more than 0.001 wt.%, preferably more than 0.01 wt.%, and / or less than 10 wt.%, preferably less than 5 wt.%, preferably less than 3 wt.%, of a dielectric liquid by total weight of the heat transfer fluid composition.

[0122] In certain embodiments, the heat transfer fluid composition comprises 0.0001 to 10 wt. %, preferably 0.001 to 5 wt. %, preferably 0.01 to 1 wt. %, of the dielectric liquid by the total weight of the heat transfer fluid composition.

[0123]

[0123] In certain embodiments, the heat transfer fluid composition comprises, as a further additive, one or more dyes, preferably non-ionic dyes such as those disclosed in European Patent No. 1809718 B1 and Korean Patent No. 102108349 B1.

[0124]

[0124] In some embodiments, the heat transfer fluid composition comprises one or more dyes in an amount greater than 0.001 wt. %, preferably greater than 0.005 wt. %, preferably greater than 0.01 wt. % and / or less than 1 wt. %, preferably less than 0.5 wt. %, preferably less than 0.1 wt. %, by total weight of the heat transfer fluid composition.

[0125]

[0125] In certain embodiments, the heat transfer fluid composition comprises, as a further additive for safety reasons, one or more bittering agents, preferably in an amount of less than 100 ppm, preferably less than 80 ppm, less than 60 ppm, less than 40 ppm or less than 20 ppm by total weight of the heat transfer fluid composition.

[0126]

[0126] In certain embodiments, the heat transfer fluid composition comprises as further additives one or more polymeric viscosity modifiers such as homopolymers of ethylene oxide, random copolymers of ethylene oxide and propylene oxide, 80% hydrolyzed polyvinyl alcohol, polyalkoxy grafted polyvinyl alcohol and poly(vinyl alcohol-co-ethylene), preferably in an amount of more than 0.001 wt.%, preferably more than 0.005 wt.%, preferably more than 0.01 wt.% and / or less than 10 wt.%, preferably less than 5 wt.%, preferably less than 3 wt.% by total weight of the heat transfer fluid composition.

[0127]

[0127] In a preferred embodiment, the heat transfer fluid compositions defined herein are phosphate-free.

[0128] [Composition as heat transfer fluid]

[0128] In highly preferred embodiments, the heat transfer fluid compositions described below, preferably the ready-to-use heat transfer fluid compositions, are heat transfer fluids, preferably heat transfer fluids suitable for use in solar systems, fuel cells, electric motors, generators, batteries, power electronics or electronic devices, most preferably heat transfer fluids suitable for use in fuel cells or power electronics.

[0129]

[0129] As will be appreciated by those skilled in the art, depending on (for example) the intended application, the compositions according to the invention can be formulated and used in various concentrations. Thus, the heat transfer fluid composition is not particularly limited by the concentration of the divalent metal cation, the organic phosphoric acid or its salt, or other additives described herein, provided that the conductivity at 25°C is less than 500 μS / cm. Thus, depending on the envisaged application, the compositions described herein may be suitable for use as is or may require dilution with a base fluid before use. However, the inventors have found that it is particularly advantageous to provide the compositions of the invention in the form of a ready-to-use composition that may be suitable for use as a fuel cell heat transfer fluid, or in the form of a concentrate suitable for preparing said ready-to-use composition.

[0130] [Ready-to-use composition] In a highly preferred embodiment, the heat transfer fluid compositions described herein are provided in the form of a ready-to-use composition, the concentration of the organic phosphoric acid or salt thereof is in the range of 0.0001-0.05% by weight, preferably in the range of 0.0005-0.025% by weight, more preferably in the range of 0.001-0.005% by weight, based on the total weight of the ready-to-use composition; the concentration of divalent metal cations is in the range of 0.0001-0.05% by weight, preferably in the range of 0.0005-0.025% by weight, more preferably in the range of 0.001-0.005% by weight, based on the total weight of the ready-to-use composition; and The ready-to-use composition comprises more than 90% by weight, preferably more than 95% by weight, preferably more than 98% by weight, preferably more than 98.5% by weight of base fluid by the total weight of the ready-to-use composition.

[0131]

[0131] In some embodiments, the ready-to-use composition has a conductivity at 25°C of less than 350 μS / cm, preferably less than 250 μS / cm, more preferably less than 200 μS / cm, even more preferably less than 175 μS / cm, still more preferably less than 150 μS / cm, even more preferably less than 100 μS / cm, for example less than 50 μS / cm.

[0132]

[0132] In some embodiments, the ready to use composition has a conductivity at 25°C of 10 μS / cm to 500 μS / cm, 10 μS / cm to 300 μS / cm, 10 μS / cm to 250 μS / cm, 10 μS / cm to 200 μS / cm, 10 μS / cm to 175 μS / cm, 10 μS / cm to 150 μS / cm, 40 μS / cm to 150 μS / cm, 50 μS / cm to 150 μS / cm, 60 μS / cm to 150 μS / cm, 75 μS / cm to 150 μS / cm, 90 μS / cm to 150 μS / cm, 100 μS / cm to 150 μS / cm or 110 μS / cm to 150 μS / cm.

[0133]

[0133] In some embodiments, the ready to use composition has a conductivity at 25°C of 25 μS / cm to 500 μS / cm, 25 μS / cm to 250 μS / cm, 25 μS / cm to 200 μS / cm, 75 μS / cm to 200 μS / cm, or 50 μS / cm to 175 μS / cm.

[0134]

[0134] In one embodiment, the amount of divalent metal cation in the ready-to-use composition is controlled so that the molar ratio of divalent metal cation to organophosphate is in the range of 0.01-100, preferably in the range of 0.05-50, and more preferably in the range of 0.1-10.

[0135] In a preferred embodiment, the base fluid in the ready-to-use composition consists of water and an alcohol selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, monopropylene glycol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, hexapropylene glycol, methanol, ethanol, propanol, butanol, tetrahydrofurfuryl, ethoxylated furfuryl, dimethyl ether of glycerol, sorbitol, 1,2,6-hexanetriol, trimethylolpropane, methoxyethanol glycerol and mixtures thereof, preferably selected from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol, glycerol and mixtures thereof, the amount of alcohol ranging from 10 to 80% by weight, preferably from 30 to 70% by weight, depending on the total weight of the ready-to-use composition. In a particular embodiment, the amount of alcohol ranges from 10 to 45% by weight, based on the total weight of the ready-to-use composition.

[0136]

[0136] In a highly preferred embodiment, the ready to use composition has a conductivity at 25°C of less than 500 μS / cm, preferably less than 350 μS / cm, more preferably less than 250 μS / cm, even more preferably less than 225 μS / cm, still more preferably less than 175 μS / cm, even more preferably less than 150 μS / cm, and most preferably less than 100 μS / cm, the conductivity being determined after aging the heat transfer fluid at 90°C for 7 days, preferably in the presence of an aluminum substrate, more preferably in the presence of an aluminum structure manufactured via controlled atmosphere brazing (CAB), using the test procedure described in the experimental section.

[0137]

[0137] In a preferred embodiment, the ready-to-use composition has a viscosity of 0.1 to 100 mm, measured at 20°C according to ASTM standard test method D445-19a. 2 / s range, preferably 0.5 to 50 mm 2 / s range, more preferably 1 to 10 mm 2 / s range of kinematic viscosity.

[0138] [Concentrate] In a preferred embodiment, the heat transfer fluid compositions described herein are provided in the form of concentrates suitable for preparing ready-to-use compositions as described above.

[0139]

[0139] In some embodiments, the concentrate has a conductivity at 25°C of less than 200 μS / cm, preferably less than 150 μS / cm, more preferably less than 100 μS / cm, even more preferably less than 75 μS / cm, still more preferably less than 50 μS / cm, for example less than 25 μS / cm or less than 10 μS / cm.

[0140]

[0140] In some embodiments, the concentrate has a conductivity of 5-200 μS / cm, 5-150 μS / cm, 5-100 μS / cm, 5-75 μS / cm, 5-50 μS / cm, 10-100 μS / cm, 15-100 μS / cm, 20-100 μS / cm, 25-100 μS / cm, 30-100 μS / cm, 35-100 μS / cm, 40-100 μS / cm, 45-100 μS / cm or 50-100 μS / cm at 25° C.

[0141]

[0141] In some embodiments, the concentrate has a conductivity at 25°C of 10 μS / cm to 200 μS / cm, 10 μS / cm to 250 μS / cm, 10 μS / cm to 200 μS / cm, 10 μS / cm to 75 μS / cm, or 10 μS / cm to 50 μS / cm.

[0142] In a preferred embodiment, the concentrate is suitable for preparing a ready-to-use composition as described herein above by addition of water and / or alcohol, preferably by addition of water, monoethylene glycol, monopropylene glycol, 1,3-propanediol and / or glycerol, most preferably by addition of water. In a very preferred embodiment, the concentrate is suitable for preparing a ready-to-use composition as described herein above by addition of water and / or alcohol only, preferably by addition of water, monoethylene glycol, monopropylene glycol, 1,3-propanediol and / or glycerol only, most preferably by addition of water only (i.e. no other ingredients need to be added to prepare the ready-to-use composition as described herein from the concentrate).

[0143]

[0143] In some embodiments, there is provided a concentrate as defined herein, wherein the concentration of the organophosphate or salt thereof is in the range of 0.0002 to 0.1 wt. %, preferably 0.001 to 0.05 wt. %, and more preferably 0.002 to 0.01 wt. %, based on the total weight of the concentrate.

[0144]

[0144] In a preferred embodiment, there is provided a concentrate as defined herein, wherein the concentration of divalent metal cations is in the range of 0.0002 to 0.1 wt. %, preferably 0.001 to 0.05 wt. %, more preferably 0.002 to 0.01 wt. %, based on the total weight of the concentrate.

[0145]

[0145] In certain embodiments, the amount of divalent metal cation in the concentrate is controlled so that the molar ratio of divalent metal cation to organophosphate is within the range of 0.01 to 100, preferably within the range of 0.05 to 50, and more preferably within the range of 0.1 to 10.

[0146]

[0146] In a preferred embodiment, the concentrate comprises a base fluid as defined herein, a divalent metal cation and an organic phosphoric acid or salt thereof as defined herein, wherein the concentrations of both the divalent metal cation and the organic phosphoric acid or salt thereof are greater than 0.0004 wt.%, preferably greater than 0.002 wt.%, more preferably greater than 0.004 wt.%, by total weight of the concentrate, and 80 wt.%, preferably greater than 85 wt.%, preferably greater than 90 wt.% of the concentrate is an alcohol, preferably selected from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol and glycerol, most preferably monoethylene glycol.

[0147]

[0147] In a preferred embodiment, the concentrate comprises a base fluid as defined herein, a divalent metal cation and an organophosphate or salt thereof as defined herein, wherein the concentrations of both the divalent metal cation and the organophosphate or salt thereof are greater than 0.0004 wt.%, preferably greater than 0.002 wt.%, more preferably greater than 0.004 wt.%, by total weight of the concentrate, and greater than 80 wt.%, preferably greater than 85 wt.%, is water.

[0148] [Preparation method] A second aspect of the present invention is a method for preparing a heat transfer fluid composition or concentrate as defined herein, comprising the steps of: (i) providing a base fluid as defined above; (ii) providing an organophosphoric acid or a salt thereof as defined above; (iii) providing a salt of a divalent metal cation as defined above; (iv) optionally providing one or more further additives as defined above; (v) combining the base fluid of step (i) with the organophosphoric acid or salt thereof of step (ii), the salt of a divalent metal cation of step (iii) and optionally one or more further additives of step (iv) to obtain a heat transfer fluid composition or concentrate. The present invention relates to a method comprising the steps of:

[0149]

[0149] According to the present invention, the order of addition of the compounds is not particularly limited.

[0150]

[0150] In one embodiment, there is provided a method for preparing a ready-to-use composition as defined above, comprising the steps of: (i) providing a concentrate as defined above; (ii) providing water, alcohol or a mixture thereof; (iii) optionally providing one or more further additives as defined above; (iv) combining the concentrate of step (i) with water, alcohol or a mixture thereof of step (ii) and optionally one or more further additives of step (iv) to obtain a ready-to-use composition. The present invention provides a method comprising:

[0151]

[0151] In a preferred embodiment, step (iv) comprises combining more than 20% by weight of water, alcohol or mixtures thereof, preferably more than 30% or more than 50% by weight of water, alcohol or mixtures thereof by weight of the concentrate.

[0152] In a preferred embodiment, there is provided a method for preparing a ready-to-use composition as defined above, comprising the steps of: (i) providing a concentrate as defined above; (ii) providing water, alcohol or a mixture thereof; (iii) combining the concentrate of step (i) with water, alcohol or a mixture thereof of step (ii) to obtain a ready-to-use composition. A method is provided comprising:

[0153]

[0153] In a preferred embodiment, step (iii) comprises more than 50% by weight of water, alcohol or mixtures thereof, preferably more than 100%, more than 150%, more than 200% or more than 500% by weight of water, alcohol or mixtures thereof by weight of the concentrate.

[0154] According to the present invention, the alcohol in step (ii) is preferably selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, monopropylene glycol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, hexapropylene glycol, methanol, ethanol, propanol, butanol, tetrahydrofurfuryl, ethoxylated furfuryl, dimethyl ether of glycerol, sorbitol, 1,2,6-hexanetriol, trimethylolpropane, methoxyethanol, glycerol and mixtures thereof, preferably selected from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol, glycerol and mixtures thereof, preferably selected from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol and mixtures thereof.

[0155] [pH]

[0155] In some embodiments, the heat transfer fluid compositions defined herein, preferably the ready to use compositions, have a pH of 5-10, preferably 6-9.5, more preferably 7-9.

[0156] In some embodiments, the pH of the heat transfer fluid composition, preferably the ready-to-use composition, can be adjusted by the use of a buffering agent. In a preferred embodiment, a buffering system is established using any of the components described above, i.e., an organic phosphoric acid or salt thereof, a divalent metal cation and / or further additives.

[0157] [Usage / Method] Another aspect of the invention relates to an electrical system, preferably selected from the group consisting of solar systems, fuel cells, electric motors, generators, batteries, telephone transmitting stations, radio and television broadcasting stations, relay stations, electric heating or cooling devices, charging stations and high power lasers / beamers, more preferably batteries, the electrical system further comprising a heat transfer fluid composition as defined herein, preferably a ready-to-use composition as described herein. The electrical system preferably comprises aluminum in direct contact with the heat transfer fluid composition or in direct contact with the ready-to-use composition as defined herein, more preferably an aluminum structure manufactured via controlled atmosphere brazing (CAB) in direct contact with the heat transfer fluid composition or in direct contact with the ready-to-use composition as defined herein.

[0158]

[0158] Another aspect of the present invention relates to the use of a combination of an organic phosphoric acid or salt thereof and a divalent metal cation as defined above in a low-conductivity heat transfer fluid composition comprising water and alcohol as a conductivity development inhibitor and / or a corrosion inhibitor.

[0159]

[0159] In a third aspect, the present invention relates to the use of a heat transfer fluid composition or a ready-to-use composition as described hereinbefore as a heat transfer fluid having electrical conductivity inhibiting and / or corrosion inhibiting properties.

[0160]

[0160] A fourth aspect relates to the use of a heat transfer fluid composition as defined hereinbefore, preferably a ready-to-use composition as described above, for inhibiting dissolution of fluoride, aluminium and potassium ions into said heat transfer fluid composition, preferably said ready-to-use composition, from a brazing flux of an aluminium structure produced via Controlled Atmosphere Brazing (CAB), and / or for maintaining low electrical conductivity in an electrical system comprising said heat transfer fluid composition, preferably said ready-to-use composition, and an aluminium structure produced via Controlled Atmosphere Brazing (CAB).

[0161]

[0161] Another aspect of the present invention relates to the use of a heat transfer fluid composition, preferably a ready-to-use composition, as a heat transfer fluid or heat transfer fluid as described above, preferably a heat transfer fluid or heat transfer fluid in an electrical system, more preferably a heat transfer fluid or heat transfer fluid in an electrical system selected from the group consisting of solar systems, fuel cells, electric motors, generators, batteries, telephone transmission stations, power electronics, radio and television broadcast stations, relay stations, electric heating or cooling devices, preferably batteries.

[0162]

[0162] In another aspect of the present invention, there is provided a method for exchanging heat, comprising the steps of: a. generating heat from an electrical system, such as an electrical system comprising aluminum or aluminum structures produced via controlled atmosphere brazing (CAB), preferably an electrical system selected from the group consisting of solar systems, fuel cells, electric motors, generators, batteries, telephone transmission stations, power electronics, radio and television broadcast stations, relay stations, electric heating or cooling devices, preferably fuel cells or power electronics; b. contacting a heat transfer fluid composition as described herein, preferably a ready to use composition as described herein, with the electrical system of step a; c. transferring heat from the system to a heat transfer fluid composition; d. passing the composition through a heat exchanger; e. transferring heat from the heat transfer fluid composition; The present invention provides a method comprising:

[0163] [Example]

[0163] The surprising behavior of the heat transfer fluid compositions according to the invention, in particular their stability with respect to electrical conductivity on aging even in the presence of aluminum, such as aluminum structures produced via controlled atmosphere brazing (CAB), was demonstrated by immersing CAB brazed aluminum test specimens (approximately 3 x 1 x 1 cm radiator test specimens cut from radiator cores produced through CAB brazing using Nocoloc® brazing flux) in various compositions according to the invention or comparative compositions, followed by aging the compositions at 90°C for 7 days as described below.

[0164] Seven concentrates (Concentrates 1-7) were prepared containing various divalent metal cations and 2-phosphonobutane-1,2,4-tricarboxylic acid (2-PBTC) as an organic phosphate in a high weight percent of monoethylene glycol and using a small amount of ultrapure water (UPW). In addition, two concentrates (Comparative Concentrates 8-9) were prepared as reference compositions, where Comparative Concentrate 8 contained no divalent metal cations and Comparative Concentrate 9 contained neither divalent metal cations nor organic phosphates. The formulations of each concentrate are shown in Table 1 along with the pH value of the concentrates. TTZ (tolyltriazole), octanoic acid, triethanolamine and Dye Acid Green 25 were applied as further components.

[0165]

[0165] [Table 1]

[0166]

[0166] [Table 2]

[0167] From these nine concentrates, ready-to-use compositions were made by diluting the concentrates with UPW until a 50 v% solution was obtained. The pH and electrical conductivity (eCond.) of the thus diluted compositions were measured ("before aging" measurements) and are listed in Table 2.

[0168]

[0168] Then, CAB brazed aluminum specimens were added to 200 mL of ready-to-use compositions 1-9. The bottles were then placed in an oven at 90°C. After 7 days, the bottles were removed from the oven and the conductivity and pH of the aged compositions were measured. The fluoride concentrations in the aged compositions were determined by ion chromatography (Dionex ICS-6000 system equipped with an EG eluent generator and an AS11 column). The concentrations of dissolved aluminum and dissolved potassium in the aged compositions were determined by an inductively coupled plasma optical emission spectroscopy (ICP-OES) instrument (Spectro ARCOS FHS12). The experimental results are shown in Table 2.

[0169]

[0169] As can be seen from the above results, the compositions according to the invention (ready-to-use compositions 1-7) surprisingly and unexpectedly show that they can maintain low electrical conductivity in the presence of metals such as aluminum. Furthermore, the results surprisingly and unexpectedly show that the presence of both divalent metal cations and organophosphates results in improved compatibility with CAB brazing aluminum due to reduced leaching of fluoride, potassium and aluminum ions from the brazing flux into the heat transfer fluid. Leaching of fluoride, potassium and aluminum ions from the brazing flux into the heat transfer fluid is undesirable as it results in increased electrical conductivity.

[0170] It was further concluded that the ready-to-use compositions 1-7 showed no or only slight discoloration after aging at 90° C. for 7 days, whereas the comparative ready-to-use compositions 8 and 9 showed increasing discoloration from blue to green and complete discoloration, respectively. As will be appreciated by those skilled in the art, less or no discoloration means a more stable ready-to-use composition and better protection of the aluminum.

[0171] The corrosion inhibition properties of the heat transfer fluid compositions according to the present invention were established by glassware corrosion tests and high temperature surface corrosion tests.

[0172]

[0172] Glassware corrosion testing was performed according to ASTM D1384 standard test method on a ready-to-use composition made by diluting Concentrate 1 with UPW until a 33v% solution was obtained. All other test parameters were in accordance with ASTM D1384 standard test method. The results of the glassware corrosion testing are shown in Table 3.

[0173]

[0173] High temperature surface corrosion tests were performed according to ASTM D4340 standard test method on a ready-to-use composition prepared by diluting Concentrate 1 with UPW until a 25v% solution was obtained. All other test parameters were in accordance with ASTM D4340 standard test method. The results of the glassware corrosion tests can be seen in Table 4. These tests show that the ready-to-use heat transfer fluid composition according to the invention has corrosion inhibition properties for several metals and further confirm that the ready-to-use heat transfer fluid composition according to the invention has low electrical conductivity and can maintain low electrical conductivity.

[0174]

[0174] [Table 3]

[0175]

[0175] [Table 4]

[0176]

[0176] As shown in Tables 5 and 6, the prior art composition of Example 5 of US Patent Application Publication No. 2017 / 009120 was reprocessed and the electrical conductivity was measured.

[0177]

[0177] [Table 5]

[0178]

[0178] [Table 6]

[0179]

[0179] As shown in Tables 7 and 8, the prior art compositions of Examples 4, 6 and 7 from US Patent Publication No. 2014 / 061529 were reprocessed and the electrical conductivity was measured.

[0180]

[0180] [Table 7]

[0181]

[0181] [Table 8]

Claims

1. 1. A heat transfer fluid composition comprising a base fluid, a divalent metal cation, and an organic phosphoric acid or salt thereof, has a conductivity of less than 500 μS / cm at 25° C.; the base fluid comprises water and alcohol; the alcohol is present in an amount ranging from 10 to 99.5 wt. % by weight of the base fluid; A heat transfer fluid composition, wherein the composition comprises greater than 75 wt. % of the base fluid by total weight of the composition.

2. The heat transfer fluid composition of claim 1 additionally comprising one or more corrosion inhibitors.

3. 3. The heat transfer fluid composition of claim 2, wherein the one or more additional corrosion inhibitors are selected from the group consisting of silicates, phosphates, organic acids, thiazoles, triazoles, molybdates, nitrates, and amines.

4. The heat transfer fluid composition of any one of claims 1 to 3, having a conductivity of less than 350 µS / cm at 25°C.

5. 4. The heat transfer fluid composition of claim 1, wherein the alcohol is selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, monopropylene glycol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, hexapropylene glycol, methanol, ethanol, propanol, butanol, tetrahydrofurfuryl, ethoxylated furfuryl, dimethyl ether of glycerol, sorbitol, 1,2,6-hexanetriol, trimethylolpropane, methoxyethanol, glycerol, and mixtures thereof.

6. The heat transfer fluid composition of any one of claims 1 to 3, wherein the alcohol is present in an amount in the range of 30 to 70% by weight of the base fluid.

7. The heat transfer fluid composition of any one of claims 1 to 3, wherein the divalent metal cation is a divalent metal cation selected from the group consisting of alkaline earth metals and combinations thereof.

8. The heat transfer fluid composition of any one of claims 1 to 3, further comprising an anion selected from the group consisting of sulfate, nitrate, acetate, and combinations thereof.

9. The organic phosphoric acid is represented by the general formula (I): 【Chemistry 1】 (In the formula, R １ is an alkoxy chain, a hydroxyl group, an alkyl chain, an aryloxy group, or an aryl group, R ２ is an alkyl chain or an aryl group, The alkoxy chain, the alkyl chain, the aryloxy group, and the aryl group may be independently substituted with one or more of a hydroxyl group, an amine group, a phosphonic acid group or a salt thereof, and a carboxylic acid group or a salt thereof. The heat transfer fluid composition of any one of claims 1 to 3, wherein

10. The organophosphoric acid according to formula (I) is either an organophosphonic acid or an organophosphinic acid; In the case of organic phosphonic acids, R １ is either an alkoxy chain, an aryloxy group, or a hydroxyl group, and R ２ is an alkyl chain or an aryl group, In the case of organic phosphinic acids, R １ and R ２ are both independently selected from alkyl chains and aryl groups; 10. The heat transfer fluid composition of claim 9, wherein the alkoxy chain, the alkyl chain, the aryloxy group, and the aryl group may be independently substituted with one or more of a hydroxyl group, an amine group, a phosphonic acid group or a salt thereof, and a carboxylic acid group or a salt thereof.

11. The organic phosphoric acid is represented by the following formula (C): 【Chemistry 2】 (wherein n=1 to 10, and alkyl C1 to C10 is a linear or branched alkyl) 4. The heat transfer fluid composition of claim 1, wherein the organic acid is either an organic phosphonic acid or an organic phosphinic acid according to

12. The organic phosphoric acid is represented by the following formula (D): 【Transformation 3】 (wherein n=1 to 10, m=1 to 5, and alkyl C1 to C10 is a linear or branched alkyl) The heat transfer fluid composition of any one of claims 1 to 3, wherein the organic phosphonic acid is an organic phosphonic acid according to

13. The organic phosphoric acid is represented by the following formula (E): 【Chemistry 4】 (wherein n=1 to 10, m=1 to 5, and alkyl C1 to C10 is a linear or branched alkyl) The heat transfer fluid composition of any one of claims 1 to 3, wherein the organic phosphinic acid is an organic phosphinic acid according to

14. provided in the form of a ready-to-use composition, the concentration of the organic phosphoric acid or the salt thereof is in the range of 0.0001 to 0.05% by weight based on the total weight of the ready-to-use composition; the concentration of the divalent metal cation is in the range of 0.0001 to 0.05 wt. % based on the total weight of the ready-to-use composition; The heat transfer fluid composition of any one of claims 1 to 3, wherein the ready-to-use composition comprises more than 90 wt.% of the base fluid by total weight of the ready-to-use composition.

15. The heat transfer fluid composition of any one of claims 1 to 3, having a pH of from 5 to 10.

16. 15. The heat transfer fluid composition of claim 14, wherein the base fluid consists of water and an alcohol selected from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol, glycerol, and mixtures thereof, the alcohol being present in an amount ranging from 30 to 70 wt. % by weight of the base fluid.

17. 15. The heat transfer fluid composition of any one of claims 1 to 3, provided in the form of a concentrate suitable for preparing the ready-to-use composition of claim 14 by the addition of water and / or alcohol only.

18. A method for preparing the heat transfer fluid composition of any one of claims 1 to 3, comprising the steps of: (i) providing the base fluid; (ii) providing said organophosphoric acid or said salt thereof; (iii) providing a salt of said divalent metal cation; (iv) optionally providing one or more further additives; (v) combining the base fluid of step (i) with the organophosphoric acid or salt thereof of step (ii), the salt of the divalent metal cation of step (iii), and the optional one or more further additives of step (iv) to obtain the composition; A method comprising:

19. Use of the heat transfer fluid composition according to any one of claims 1 to 3 as a heat transfer fluid having conductivity inhibiting and / or corrosion inhibiting properties.

20. 4. Use of the heat transfer fluid composition according to any one of claims 1 to 3 to inhibit dissolution of fluoride, aluminium and potassium ions from brazing fluxes of aluminium structures produced via controlled atmosphere brazing (CAB) into said composition and / or to maintain low electrical conductivity in an electrical system comprising said composition and aluminium structures produced via controlled atmosphere brazing (CAB).

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