Heat transfer fluid having low electrical conductivity containing vinylpyrrolidone polymer, method for preparing the same, and use thereof

Abstract

The present invention relates to a concentrated, ready-to-use coolant composition comprising a base fluid and an N-vinylpyrrolidone polymer, the composition having an electrical conductivity at 25° C. of less than 100 μS / cm, the base fluid consisting of water and alcohol, the alcohol being present in an amount ranging from 10 to 99.5% by weight based on the weight of the base fluid, the composition comprising more than 75% by weight of base fluid based on the total weight of the composition, and the amount of inorganic compounds being less than 100 ppm based on the total weight of the composition.

Description

[Technical Field]

[0001] The present invention relates to a heat transfer fluid containing an N-vinylpyrrolidone polymer and having low electrical conductivity, which is useful for a variety of applications, such as in fuel cells. The present invention further relates to a method for preparing the heat transfer fluid, as well as a method for using the heat transfer fluid and its use. [Background technology]

[0002] Heat transfer fluids are widely used in heat exchange systems involving internal combustion engines, solar systems, fuel cells, electric motors, generators, electronic devices, battery systems, and the like. Heat transfer fluids generally consist of a base fluid and one or more additives.

[0003] Traditionally, water has been a preferred base fluid in terms of heat transfer properties. In many applications, antifreeze properties are required, and in such cases, a base fluid consisting of water mixed with a freezing point depressant such as alcohol, glycol, or salt is used. By using additives present in the heat transfer fluid, various functionalities can be obtained, such as (further) lowering of the freezing point, improvement of heat exchange properties, and inhibition of corrosion. 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] A fuel cell is an electrochemical battery that converts stored chemical energy into electrical energy through the controlled oxidation of a fuel. Due to its relatively low pollutant emissions compared to combustion engines, fuel cells are an attractive option for applications such as automobiles and power plants. In most applications, several electrochemical batteries are stacked in series to form a so-called fuel cell stack, which allows for the generation of higher voltages. The heat generated by the fuel cell stack can be removed by flowing a coolant through grooves formed by bipolar plates.

[0005] The potential difference between the positive and negative electrodes of a fuel cell stack can cause shunt current to flow through the coolant, thus lowering the fuel cell voltage. In addition to this harmful voltage drop, the shunt current causes further problems, such as corrosion of the separator plate near the positive electrode of the fuel cell stack. Therefore, coolants used in electrical applications such as fuel cells must have low electrical conductivity (i.e., high electrical resistance) and be able to maintain this throughout the lifespan of the coolant.

[0006] The most well-known heat transfer fluids (e.g., coolants) are specifically designed for internal combustion engines and are unsuitable for use in electrical applications such as fuel cells, batteries, or power electronics because they (i) have high electrical conductivity or (ii) become significantly more electrically conductive when aged, especially at high temperatures. The increase in electrical conductivity during aging is generally attributed to the decomposition of alcohols, particularly glycols, often used as the base fluid, the decomposition of additives, metal corrosion, and / or the formation of ionic compounds due to impurities in the cooling circuit.

[0007] Therefore, in recent years, there has been growing interest in developing heat transfer fluids suitable for use in electrical applications such as fuel cells.

[0008] U.S. Patent Application Publication No. 2005 / 0109979A1 describes a heat transfer fluid for electric vehicles comprising a base agent and a rust-preventive additive which is an amide compound, imide compound, or azole compound that inhibits oxidation of the base agent or prevents ions from leaching into the cooling system and prevents an increase in the electrical conductivity of the coolant.

[0009] European Patent No. 1739775B1 describes a heat transfer fluid comprising a base agent and a rust-preventive additive which is a sugar alcohol and suppresses oxidation of the base agent and prevents an increase in electrical conductivity.

[0010] Known heat transfer fluids capable of maintaining low electrical conductivity have several disadvantages. These include, for example, the reliance on the presence of additives that may be costly, toxic, or otherwise possess undesirable properties. Furthermore, since additives used in the art to maintain low electrical conductivity are often consumed in the process, large quantities of additives are required for practical use, which may also undesirably affect other properties of the heat transfer fluid.

[0011] Alcohol-based, such as glycol-based, heat transfer fluids offer several advantages. For example, they have a low freezing point combined with low viscosity and a high flash point, and the safety profiles of different glycols have been extensively studied.

[0012] The inventors have found it particularly desirable to provide alcohol-based, especially glycol-based, heat transfer fluids that can maintain low electrical conductivity during aging in the presence of aluminum. Due to their lightweight nature, aluminum-based materials are often preferred for components such as cooling plates and heat exchangers.

[0013] The object of the present invention is to provide improved heat transfer fluids, preferably alcohol-based, which are suitable for use as coolants in electrical systems such as fuel cells, batteries, or power electronics.

[0014] Therefore, an object of the present invention is to provide preferably alcohol-based heat transfer fluids that have low electrical conductivity, which can maintain low electrical conductivity during aging, such as when aged at elevated temperatures.

[0015] A further object of the present invention is to provide preferably alcohol-based heat transfer fluids that can maintain comparable low electrical conductivity during aging, such as when aged at elevated temperatures, without requiring as many additives as known heat transfer fluids.

[0016] A further objective of the present invention is to provide a glycol-based heat transfer fluid that has a longer effective life compared to known heat transfer fluids. [Overview of the project] [Means for solving the problem]

[0017] The inventors have found that one or more of these objectives can be achieved by using a coolant composition comprising a basic fluid and an N-vinylpyrrolidone polymer, wherein the N-vinylpyrrolidone polymer is selected from polyvinylpyrrolidone homopolymer and polyvinylpyrrolidone copolymer, and the composition has an electrical conductivity of less than 100 μS / cm at 25°C.

[0018] As shown in the attached examples, it was surprisingly found that the N-vinylpyrrolidone polymer maintained low electrical conductivity when aged at elevated temperatures. Furthermore, it was surprisingly found that the coolant compositions according to this specification could maintain this low electrical conductivity when aged at elevated temperatures in the presence of an aluminum substrate using the test procedures described in the Experiments section.

[0019] Those skilled in the art will understand, based on this disclosure, that the coolant compositions described herein effectively enable the provision of heat transfer fluids or coolants suitable for use in electrical applications that require fewer additives (particularly antioxidants) and / or can maintain lower electrical conductivity during aging for longer periods than comparable coolant compositions known in the art. While not wishing to be bound by any theory, the inventors believe that, as can be seen from experimental results, the electrical conductivity of aged samples may correlate with the amount of alcohol-related, particularly glycol-related, oxidation products, glycolates, and formates present in the mixture. It is thought that the N-vinylpyrrolidone polymer interacts with the metal surface to form a (weakly bonded) film that is effective in either way in separating metal ions from the heat transfer fluid and the metal substrate.

[0020] Polyvinylpyrrolidone is known as a hard water stabilizer in antifreeze concentrates for internal combustion engines (see, for example, US Patent Application Publication No. 2008 / 0001118A1). However, the use of N-vinylpyrrolidone polymers for maintaining low electrical conductivity in coolant compositions has not been known in the art yet.

[0021] Accordingly, in a first aspect, the present invention provides a coolant composition comprising a base fluid and an N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, wherein the composition has an electrical conductivity at 25°C of less than 100 μS / cm, the base fluid consists of water and an alcohol, the alcohol is present in an amount ranging from 10 to 99.5% by weight based on the weight of the base fluid, the composition comprises more than 75% by weight of the base fluid based on the total weight of the composition, and the amount of inorganic compounds is less than 100 ppm based on the total weight of the composition. As shown herein, these coolant compositions are capable of maintaining low electrical conductivity when aged at elevated temperatures in the presence of an aluminum substrate (EN AC-AlSi10Mg(a)T6, DIN EN 1706) using the test procedure described in the experimental section herein.

[0022] In a preferred embodiment, the coolant composition of the present invention is provided in the form of a ready-to-use composition as described herein.

[0023] In another aspect, the present invention provides a method for preparing the composition described herein.

[0024] In another aspect, the present invention provides a method for preparing the ready-to-use composition described herein from a concentrate.

[0025] In another aspect, the present invention provides the corresponding use of an N-vinylpyrrolidone polymer. Mode for Carrying Out the Invention

[0026] A first aspect of the present invention relates to a coolant composition comprising a base fluid and an N-vinylpyrrolidone polymer selected from polyvinylpyrrolidone homopolymer and polyvinylpyrrolidone copolymer, wherein the composition has an electrical conductivity of less than 100 μS / cm at 25°C, the base fluid consists of water and alcohol, wherein the alcohol is present in an amount ranging from 10 to 99.5% by weight based on the weight of the base fluid, the composition contains more than 75% by weight of the base fluid based on the total weight of the composition, and the amount of inorganic compound is less than 100 ppm based on the total weight of the composition.

[0027] The coolant composition preferably has an electrical conductivity at 25°C of less than 50 μS / cm, more preferably less than 25 μS / cm, even more preferably less than 10 μS / cm, and even more preferably less than 5 μS / cm.

[0028] basic fluid In accordance with the present invention, the basic fluid consists of water and alcohol. In preferred embodiments, 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, and more preferably selected from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol, glycerol, and mixtures thereof.

[0029] As used herein, "monoethylene glycol" should be interpreted as meaning "ethane-1,2-diol" and is interchangeably referred to as "MEG".

[0030] As used herein, "monopropylene glycol" should be interpreted as meaning "propane-1,2-diol" and is interchangeably referred to as "MPG".

[0031] As used herein, the term "glycerol" means "propane-1,2,3-triol" and is synonymous with glycerin. In preferred embodiments of the present invention, the basic fluid consists of water, monoethylene glycol, monopropylene glycol, 1,3-propanediol, glycerol, or a mixture thereof.

[0032] The base fluid consists of water and alcohol, where the alcohol is present in an amount of 10 to 99.5% by weight (based on the weight of the base fluid), preferably 10 to 80% by weight, and more preferably 30 to 70% by weight. In certain embodiments, the alcohol is present in an amount ranging from 33 to 60% by weight (based on the weight of the base fluid).

[0033] In embodiments of the present invention, the base fluid comprises more than 50% by weight of water, preferably more than 70% by weight, and more preferably more than 85% by weight (based on the weight of the base fluid).

[0034] In embodiments of the present invention, the base fluid contains more than 50% by weight of monoethylene glycol (based on the weight of the base fluid), preferably more than 70% by weight, more preferably more than 85% by weight, and most preferably more than 95% by weight of monoethylene glycol.

[0035] In embodiments of the present invention, the base fluid contains more than 50% by weight of monopropylene glycol (based on the weight of the base fluid), preferably more than 70% by weight, more preferably more than 85% by weight, and most preferably more than 95% by weight of monopropylene glycol.

[0036] In embodiments of the present invention, the base fluid contains more than 50% by weight of 1,3-propanediol, preferably more than 70% by weight, more preferably more than 85% by weight, and most preferably more than 95% by weight of 1,3-propanediol (based on the weight of the base fluid).

[0037] In embodiments of the present invention, the base fluid contains more than 50% by weight of glycerol (based on the weight of the base fluid), preferably more than 70% by weight, more preferably more than 85% by weight, and most preferably more than 95% by weight of glycerol.

[0038] In preferred embodiments of the present invention, compositions described herein are provided that comprise more than 78% by weight of a base fluid, more preferably more than 85% by weight, even more preferably more than 90% by weight, and even more preferably more than 95% by weight or more than 98% by weight of a base fluid (based on the total weight of the composition).

[0039] As will be understood by those skilled in the art, the base fluid is usually added to the composition in an "appropriate amount". In embodiments of the present invention, the composition contains less than 99.9% by weight of the base fluid (based on the total weight of the composition), for example less than 99.8% by weight, less than 99.5% by weight, or less than 99% by weight, less than 98% by weight, less than 97% by weight, less than 96% by weight, less than 95% by weight, less than 94% by weight, less than 93% by weight, less than 92% by weight, less than 91% by weight, less than 90% by weight, less than 89% by weight, less than 88% by weight, less than 87% by weight, less than 86% by weight, less than 85% by weight, less than 84% by weight, less than 83% by weight, less than 82% by weight, or less than 81% by weight of the base fluid.

[0040] In preferred embodiments of the present invention, compositions described herein are provided that contain less than 99.9% by weight of a base fluid, or less than 99.5% by weight, or less than 99% by weight (based on the total weight of the composition).

[0041] N-vinylpyrrolidone polymer In accordance with the present invention, the compositions described herein include an N-vinylpyrrolidone polymer, preferably a polyvinylpyrrolidone homopolymer, selected from polyvinylpyrrolidone homopolymers and polyvinylpyrrolidone copolymers. Therefore, as used herein, the term N-vinylpyrrolidone polymer refers to a polymer derived from a monomer containing or comprising N-vinylpyrrolidone, also known as N-vinyl-2-pyrrolidone. Whenever the term "polyvinylpyrrolidone" is used in this document without specifying an adduct (e.g., homopolymer or copolymer) or additional provisions, polyvinylpyrrolidone homopolymer is referred to as polyvinylpyrrolidone (i.e., homopolymer), abbreviated as PVP, and is a water-soluble polymer synthesized by polymerization from the monomer N-vinylpyrrolidone, where n defines the degree of polymerization of the polymer (see diagram below). Polyvinylpyrrolidone is also commonly known as polyvidone, povidone, poly[1-(2-oxo-1-pyrrolidinyl)ethylene], 1-ethenyl-2-pyrrolidone homopolymer, or 1-vinyl-2-pyrrolidinone polymer. Its chemical formula is (C6H9NO). n It is a CAS number of 9003-39-8. [ka]

[0042] In certain preferred embodiments, the N-vinylpyrrolidone polymer is a polyvinylpyrrolidone homopolymer, meaning that polyvinylpyrrolidone is derived from one species of monomer, which is N-vinylpyrrolidone. In other preferred embodiments, the N-vinylpyrrolidone polymer is a polyvinylpyrrolidone copolymer, meaning that polyvinylpyrrolidone is derived from two or more species of monomer, particularly N-vinylpyrrolidone, combined with at least one other monomer. Non-limiting examples of such other monomers include styrene, vinyl acetate, ethylene, propylene, tetrafluoroethylene, methyl methacrylate, vinyl chloride, and ethylene oxide.

[0043] In preferred embodiments, the polyvinylpyrrolidone copolymer is derived from N-vinylpyrrolidone and at least one other monomer, where the percentage of N-vinylpyrrolidone monomer is at least 10%, more preferably at least 25%, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95%, based on the total number of monomers in the polyvinylpyrrolidone copolymer. As will be understood by those skilled in the art, the minimum percentage of N-vinylpyrrolidone monomer based on the total number of monomers in the polyvinylpyrrolidone copolymer is determined, in particular, by the solubility of the polyvinylpyrrolidone copolymer in the composition, more specifically, by its solubility in the underlying fluid.

[0044] Preferred polyvinylpyrrolidone copolymers that can be applied in the compositions according to the present invention include copolymers of N-vinylpyrrolidone and vinyl acetate (where the percentage of N-vinylpyrrolidone monomer is at least 25% based on the total number of monomers in the polyvinylpyrrolidone copolymer), hydrolyzed forms of copolymers of N-vinylpyrrolidone and vinyl acetate (where the percentage of N-vinylpyrrolidone monomer is at least 10% based on the total number of monomers in the polyvinylpyrrolidone copolymer), and copolymers of N-vinylpyrrolidone and N-vinylcaprolactam (where the percentage of N-vinylpyrrolidone monomer is at least 40% based on the total number of monomers in the polyvinylpyrrolidone copolymer).

[0045] In accordance with the present invention, the N-vinylpyrrolidone polymer is particularly preferably a polyvinylpyrrolidone homopolymer.

[0046] According to the present invention, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a weight-average molecular weight M in the range of 500 to 2,500,000 g / mol. w It has. As will be understood by those skilled in the art, the weight-average molecular weight is the weight fraction of molecules in a polymer sample and gives the average molecular mass of single macromolecules in the polymer sample. The weight-average molecular weight as defined herein is given by the formula Mw =(ΣN i M i 2 ) / (ΣN i M i It is determined using ). Those skilled in the art know different techniques for determining the weight-average molecular weight of polymers of various chain lengths. The weight-average molecular weight and the corresponding measurement method are typically shown on the product data sheet of the polymer under consideration.

[0047] In certain embodiments of the present invention, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a weight-average molecular weight in the range of 3,000 to 2,500,000 g / mol, preferably 5,000 to 2,250,000 g / mol, more preferably 7,500 to 2,000,000 g / mol, and even more preferably 8,000 to 1,800,000 g / mol.

[0048] In certain embodiments of the present invention, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a weight-average molecular weight in the range of 3,000 to 700,000 g / mol, preferably 5,000 to 500,000 g / mol, more preferably 7,500 to 250,000 g / mol, and even more preferably 8,000 to 100,000 g / mol. N-vinylpyrrolidone polymers, preferably polyvinylpyrrolidone, having these weight-average molecular weight ranges are preferred because they have a lower kinematic viscosity, thereby improving the resulting charge transfer of the composition, which is beneficial for the properties of a coolant with low electrical conductivity.

[0049] In certain embodiments of the present invention, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a weight-average molecular weight in the range of 700,000 to 2,500,000 g / mol, preferably in the range of 750,000 to 2,250,000 g / mol, more preferably in the range of 850,000 to 2,000,000 g / mol, and even more preferably in the range of 1,000,000 to 1,800,000 g / mol.

[0050] In a preferred embodiment, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a weight average molecular weight in the range of 500 to 50,000 g / mol, more preferably in the range of 1,000 to 15,000 g / mol, even more preferably in the range of 1,500 to 10,000 g / mol, for example about 2000 g / mol, about 2500 g / mol, about 5000 g / mol or about 8000 g / mol.

[0051] N-vinylpyrrolidone polymers that can be suitably used as additives are commercially available from commercial suppliers such as BASF, Sigma-Aldrich or Nippon Shokubai. Examples of commercially available polyvinylpyrrolidone include Luvitec K17 (M W = 9,000 g / mol), Luvitec K30 (M W = 50,000 g / mol), Luvitec K90 (M W = 1,400,000 g / mol) and PVP K30.

[0052] In an embodiment of the present invention, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, when used as the sole additive at a concentration of N-vinylpyrrolidone polymer in the range of 0.0001 to 1% by weight; preferably N-vinylpyrrolidone polymer in the range of 0.00015 to 0.5% by weight; most preferably N-vinylpyrrolidone polymer in the range of 0.0002 to 0.5% by weight, in a base fluid consisting of 30 to 60% by weight of MEG in water, can maintain an electrical conductivity at 25°C of less than 50 µS / cm, preferably less than 25 µS / cm, preferably less than 10 µS / cm, more preferably less than 5 µS / cm, most preferably less than 2 µS / cm, wherein the electrical conductivity is measured after aging the heat transfer fluid at 90°C for 14 days in the presence of, for example, an aluminum substrate (EN AC-AlSi10Mg(a)T6, DIN EN 1706) using the test procedure described in the Experimental Section.

[0053] In certain preferred embodiments, an N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, having a weight-average molecular weight of 500 to 12,000 g / mol, can maintain an electrical conductivity of less than 50 μS / cm, preferably less than 25 μS / cm, preferably less than 10 μS / cm, more preferably less than 5 μS / cm, and most preferably less than 2 μS / cm at 25°C when used as the sole additive at a concentration of 0.002 to 0.5 wt% of the N-vinylpyrrolidone polymer in a base fluid consisting of 30 to 60 wt% MEG in water, where the electrical conductivity is measured after aging the heat transfer fluid at 90°C for 14 days in the presence of an aluminum substrate (EN AC-AlSi10Mg(a)T6, DIN EN 1706) using the test procedure described in the Experiments section.

[0054] In certain preferred embodiments, an N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, having a weight-average molecular weight of 20,000 to 50,000 g / mol, can maintain an electrical conductivity of less than 50 μS / cm, preferably less than 25 μS / cm, preferably less than 10 μS / cm, more preferably less than 5 μS / cm, and most preferably less than 2 μS / cm at 25°C when used as the sole additive at a concentration of 0.002 to 0.5 wt% of the N-vinylpyrrolidone polymer in a base fluid consisting of 30 to 60 wt% MEG in water, where the electrical conductivity is measured after aging the heat transfer fluid at 90°C for 14 days in the presence of an aluminum substrate (EN AC-AlSi10Mg(a)T6, DIN EN 1706) using the test procedure described in the Experiments section.

[0055] In the embodiment, an N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, having a weight-average molecular weight of 40,000 to 80,000 g / mol, can maintain an electrical conductivity of less than 50 μS / cm, preferably less than 25 μS / cm, preferably less than 10 μS / cm, more preferably less than 5 μS / cm, and most preferably less than 2 μS / cm at 25°C when used as the sole additive at a concentration of 0.0002 to 0.5 wt% of the N-vinylpyrrolidone polymer in a base fluid consisting of 30 to 60 wt% MEG in water, where the electrical conductivity is measured after aging the heat transfer fluid at 90°C for 14 days in the presence of an aluminum substrate (EN AC-AlSi10Mg(a)T6, DIN EN 1706) using the test procedure described in the Experiments section.

[0056] In preferred embodiments, an N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, having a weight-average molecular weight of 500 to 50,000 g / mol, more preferably 1,000 to 15,000 g / mol, and even more preferably 1,500 to 10,000 g / mol, can maintain an electrical conductivity at 25°C of less than 50 μS / cm, preferably less than 25 μS / cm, preferably less than 10 μS / cm, more preferably less than 5 μS / cm, and most preferably less than 2 μS / cm, when used as the sole additive at a concentration of 0.0002 to 0.5 wt% of the N-vinylpyrrolidone polymer in a base fluid consisting of 30 to 60 wt% MEG in water, where the electrical conductivity is measured after aging the heat transfer fluid at 90°C for 14 days in the presence of an aluminum substrate (EN AC-AlSi10Mg(a)T6, DIN EN 1706) using the test procedure described in the Experiments section.

[0057] Electrical conductivity In embodiments of the present invention, a coolant composition described herein is provided having the electrical conductivity described elsewhere herein when measured according to ASTM D1125 by a Radiometer Copenhagen CDM210 electrical conductivity meter using a Radiometer Copenhagen CDC745 conductivity cell and a Radiometer Copenhagen temperature sensor T201.

[0058] In embodiments of the present invention, a coolant composition described herein is provided which has an electrical conductivity at 25°C of less than 50 μS / cm, preferably less than 25 μS / cm, preferably less than 10 μS / cm, more preferably less than 5 μS / cm, and even more preferably less than 2 μS / cm, after being optionally aged for 14 days at 90°C in the presence of aluminum (EN AC-AlSi10Mg(a)T6, DIN EN 1706) using the test procedure described in the Experimental section.

[0059] In embodiments of the present invention, a coolant composition is provided wherein the concentration of glycolate and / or formate is less than 30 ppm, preferably less than 10 ppm, more preferably less than 5 ppm, after being optionally aged for 14 days at 90°C in the presence of aluminum (EN AC-AlSi10Mg(a)T6, DIN EN 1706) using the test procedure described in the Experimental section, and the concentrations of glycolate and / or formate are less than 30 ppm, preferably less than 10 ppm, more preferably less than 5 ppm, where the concentrations of glycolate and formate are measured by ion chromatography.

[0060] Inhibition of corrosion As described throughout this document, the coolant compositions according to this specification exhibit the electrical conductivity properties described herein with minimal corrosion of aluminum. Accordingly, embodiments of the present invention provide compositions according to this specification in which an aluminum coupon (EN AC-AlSi10Mg(a)T6, DIN EN 1706) immersed in the composition exhibits a weight loss of less than 20 mg, preferably less than 10 mg, and preferably less than 2 mg, when tested using the procedure described in the Experiments section.

[0061] inorganic compounds The compositions described herein in accordance with the present invention may contain inorganic compounds. If present, the (total) amount of inorganic compounds is less than 100 ppm based on the total weight of the coolant composition. As will be understood by those skilled in the art, inorganic compounds do not contain carbon-hydrogen bonds. In contrast, organic compounds such as organic rust inhibitors that can be used in the compositions according to the present invention do not contain carbon-hydrogen bonds.

[0062] As will be understood by those skilled in the art, high concentrations of inorganic compounds, particularly inorganic compounds in salt form, can increase the electrical conductivity of the coolant composition, which leads to a decrease in fuel cell voltage and corrosion of the separator plate, making them unsuitable for use in fuel cells. Accordingly, the coolant compositions described herein typically exhibit a decrease in electrical conductivity when the amount of inorganic compounds is 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, based on the total weight of the composition.

[0063] In certain embodiments of the present invention, the coolant composition defined herein may contain a certain inorganic rust inhibitor in an amount greater than, for example, 1 ppm, 3 ppm, or 5 ppm based on the total weight of the composition, provided that the electrical conductivity of the composition at 25°C is less than 100 μS / cm.

[0064] In embodiments of the present invention, the coolant composition defined herein comprises an inorganic rust inhibitor selected from the group consisting of silicates, molybdates, nitrates, nitrites, borates, tungstates, sulfates, sulfites, carbonates, phosphonates, selenates, and phosphates.

[0065] In preferred embodiments, the coolant composition as defined herein does not contain borax, sodium nitrate, sodium nitrite, sodium silicate, or sodium benzoate.

[0066] In preferred embodiments, the coolant composition defined herein does not contain carbon black.

[0067] In preferred embodiments, the coolant composition defined herein does not contain borates and cerium nitrate.

[0068] In preferred embodiments, the coolant composition defined herein does not contain water-soluble molybdates, nitrites, or nitrates.

[0069] In preferred embodiments, the coolant composition defined herein does not contain potassium hydroxide.

[0070] Additional additives As will be understood by those skilled in the art, based on the teachings presented herein, the coolant compositions according to this specification may include one or more additional additives that are customary in the art. Determining how much of a particular additive can be added so that the electrical conductivity of the resulting composition conforms to the present invention is within the scope of the routine skills of those skilled in the art. As will be understood by those skilled in the art, nonionic additional additives are preferred. The coolant compositions contain clearly defined amounts of water, alcohol, N-vinylpyrrolidone polymer, and inorganic compounds. Thus, one or more additional additives are different from water, alcohol, N-vinylpyrrolidone polymer, and inorganic compounds.

[0071] In certain embodiments of the present invention, the compositions provided herein include one or more additional additives, preferably one or more additional additives selected from the group consisting of corrosion inhibitors, liquid dielectrics, antioxidants, abrasion inhibitors, detergents, and defoamers. In preferred embodiments, the compositions of the present invention further include one or more of the additional additives in an amount ranging from 0.001 to 10% by weight, preferably 0.01 to 5% by weight, and more preferably 0.02 to 3% by weight (based on the total weight of the composition).

[0072] In preferred embodiments, the coolant composition of the present invention further comprises one or more additional additives selected from the group consisting of thiazoles, triazoles, polyolefins, polyalkylene oxides, silicone oils, silicate esters (e.g., Si(OR)4 (where R is a C1-C4 alkyl group)), mineral oils, monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids. In preferred embodiments, the coolant composition of the present invention further comprises one or more of the above additives in an amount ranging from 0.001 to 10% by weight, preferably 0.01 to 5% by weight, and more preferably 0.02 to 3% by weight (based on the total weight of the composition).

[0073] In preferred embodiments of the present invention, a coolant composition as defined herein is provided, comprising a corrosion inhibitor, preferably an aromatic triazole or thiazole, as an additional additive. In preferred embodiments of the present invention, a coolant composition as defined herein is provided, comprising one or more triazoles selected from the group consisting of toltriazole, benzotriazole, and combinations thereof, as an additional additive.

[0074] Embodiments of the present invention provide a coolant composition as defined herein, comprising, as an additional additive, triazole or thiazole, preferably toltriazole or benzotriazole, in an amount of more than 0.001% by weight, preferably more than 0.01% by weight, preferably more than 0.1% by weight and / or less than 10% by weight, preferably less than 5% by weight, preferably less than 3% by weight (based on the total weight of the composition).

[0075] Embodiments of the present invention provide compositions as defined herein, comprising a defoaming agent as an additional additive. Preferably, the defoaming agent is selected from the group consisting of polyalkylene oxides, silicone polymers (e.g., 3D silicone polymers), or silicone oils.

[0076] Embodiments of the present invention provide a coolant composition as defined herein, comprising, as an additional additive, a defoaming agent in an amount of more than 0.001% by weight, preferably more than 0.005% by weight, preferably more than 0.01% by weight and / or less than 10% by weight, preferably less than 5% by weight, preferably less than 3% by weight (based on the total weight of the composition).

[0077] In embodiments of the present invention, a coolant composition as defined herein is provided, comprising, as an additional additive, a corrosion inhibitor selected from the group consisting of aromatic carboxylates, aliphatic monocarboxylates, aliphatic dicarboxylates, aliphatic tricarboxylates, and polymer corrosion inhibitors.

[0078] In embodiments of the present invention, an aliphatic monocarboxylate, preferably C4-C4, may be used as an additional additive. 12 A coolant composition as defined herein is provided, comprising an aliphatic monocarboxylate selected from the group consisting of aliphatic monocarboxylates in an amount (based on the total weight of the composition) 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.

[0079] In embodiments of the present invention, an aliphatic dicarboxylate, preferably C6-C, may be used as an additional additive. 16 A coolant composition as defined herein is provided, comprising an aliphatic dicarboxylate selected from the group consisting of aliphatic dicarboxylates in an amount (based on the total weight of the composition) 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, and preferably less than 1000 ppm.

[0080] In embodiments of the present invention, an aliphatic tricarboxylate, preferably C7-C7, is used as an additional additive. 18A coolant composition as defined herein is provided, comprising an aliphatic tricarboxylate selected from the group consisting of aliphatic tricarboxylates in an amount (based on the total weight of the composition) 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, and preferably less than 1000 ppm.

[0081] In embodiments of the present invention, a coolant composition as defined herein is provided, comprising, as an additional 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 (based on the total weight of the composition) 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, and preferably less than 1000 ppm.

[0082] In embodiments of the present invention, a coolant composition as defined herein is provided, comprising an antioxidant as an additional 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 alkylphenyl-2-naphthalamine, and sulfur-containing compounds.

[0083] Embodiments of the present invention provide a coolant composition as defined herein, comprising an antioxidant as an additional additive in an amount greater than 0.001% by weight, preferably greater than 0.005% by weight, preferably greater than 0.01% by weight and / or less than 10% by weight, preferably less than 5% by weight, preferably less than 3% by weight (based on the total weight of the composition).

[0084] Embodiments of the present invention provide a coolant composition as defined herein, comprising an anti-wear agent as an additional additive.

[0085] Embodiments of the present invention provide a coolant composition as defined herein, comprising an anti-wear agent as an additional additive in an amount of more than 0.001% by weight, preferably more than 0.005% by weight, preferably more than 0.01% by weight and / or less than 10% by weight, preferably less than 5% by weight, preferably less than 3% by weight (based on the total weight of the composition).

[0086] Embodiments of the present invention provide a coolant composition as defined herein, comprising one or more surfactants as additional additives. In preferred embodiments, the one or more surfactants are, for example: • Fatty acid esters such as sorbitan fatty acid esters; • Polyalkylene amide glycol; • Polyalkylene amide glycol ester; • Copolymers and block copolymers of ethylene oxide and propylene oxide; • Polyoxyalkylene derivatives of sorbitan fatty acid esters; and • Alkoxylated alcohol ethers One or more nonionic surfactants selected from the group consisting of nonionic surfactants, such as one or more nonionic surfactants selected from the group consisting of the following.

[0087] Embodiments of the present invention provide a coolant composition as defined herein, comprising one or more surfactants in an amount greater than 0.001% by weight, preferably greater than 0.005% by weight, preferably greater than 0.01% by weight and / or less than 10% by weight, preferably less than 5% by weight, preferably less than 3% by weight (based on the total weight of the composition).

[0088] In certain embodiments of the present invention, a coolant composition as defined herein is provided, comprising a dielectric liquid as an additional additive. Preferred dielectric liquids are mineral oil, silicone oil, and mixtures thereof.

[0089] In certain embodiments of the present invention, the coolant composition provided herein comprises more than 0.0001% by weight of a dielectric liquid (based on the total weight of the composition), preferably more than 0.001% by weight, preferably more than 0.01% by weight and / or less than 10% by weight, preferably less than 5% by weight, and preferably less than 3% by weight.

[0090] In certain embodiments of the present invention, the coolant composition provided herein contains 0.0001 to 10% by weight of a dielectric liquid, preferably 0.001 to 5% by weight, and preferably 0.01 to 1% by weight (based on the total weight of the composition).

[0091] In certain embodiments of the present invention, a coolant composition as defined herein is provided, which preferably contains, as an additional additive, one or more nonionic dyes, such as nonionic dyes disclosed in European Patent No. 1809718B1 and Korean Patent No. 102108349B1, in an amount of more than 0.001% by weight, preferably more than 0.005% by weight, preferably more than 0.01% by weight and / or less than 10% by weight, preferably less than 5% by weight, preferably less than 3% by weight (based on the total weight of the composition).

[0092] In certain embodiments of the present invention, for safety reasons, a coolant composition as defined herein is provided, which preferably contains one or more bittering agents as additional additives 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 (based on the total weight of the composition).

[0093] In certain embodiments of the present invention, a coolant composition as defined herein is provided, which preferably contains, as an additional additive, one or more polymer viscosity modifiers such as ethylene oxide homopolymers, random copolymers of ethylene oxide and propylene oxide, 80% hydrolyzed polyvinyl alcohol, polyalkoxygrafted polyvinyl alcohol and poly(vinyl alcohol-co-ethylene) in an amount of more than 0.001% by weight, preferably more than 0.005% by weight, preferably more than 0.01% by weight and / or less than 10% by weight, preferably less than 5% by weight, preferably less than 3% by weight.

[0094] Composition as a heat transfer fluid In a very preferred embodiment, the coolant compositions described herein, preferably ready-to-use coolant compositions, are preferably heat transfer fluids suitable for use in solar systems, fuel cells, electric motors, generators, batteries, battery electric vehicles, power electronics, or electronic devices, and most preferably heat transfer fluids suitable for use in fuel cells or power electronics.

[0095] As will be understood by those skilled in the art, the compositions according to the present invention can be formulated and used at various concentrations depending on the intended application (for example). Accordingly, the coolant compositions are not particularly limited by the concentration of the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, or other additives described herein. Accordingly, depending on the expected 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 it particularly advantageous to provide the compositions of the present invention in the form of ready-to-use compositions suitable for use as fuel cell coolants, or in the form of concentrates suitable for preparing such ready-to-use compositions.

[0096] Ready-to-use compositions In a very preferred embodiment of the present invention, a coolant composition described herein is provided in the form of a ready-to-use composition which is a heat transfer fluid, where: The concentration of N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, is in the range of 0.0001 to 10% by weight, preferably in the range of 0.00015 to 5% by weight, more preferably in the range of 0.0002 to 2% by weight, based on the total weight of the composition, and The composition contains more than 90% by weight, preferably more than 95% by weight, preferably more than 98% by weight, and preferably more than 99% by weight of the base fluid, based on the total weight of the composition.

[0097] In embodiments of the present invention, the ready-to-use compositions provided herein comprise an N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, having a weight-average molecular weight in the range of 500 to 2,500,000 g / mol, preferably 3,000 to 2,500,000 g / mol, more preferably 5,000 to 2,250,000 g / mol, even more preferably 7,500 to 2,000,000 g / mol, and most preferably 8,000 to 1,800,000 g / mol; where the N-vinylpyrrolidone polymer has a concentration in the range of 0.0001 to 10% by weight, preferably 0.00015 to 5% by weight, and more preferably 0.0002 to 3% by weight, based on the total weight of the composition. In certain preferred embodiments, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a concentration in the ready-to-use composition of more than 0.0001% by weight, more than 0.0002% by weight, more than 0.0003% by weight, more than 0.0005% by weight, more than 0.001% by weight, more than 0.002% by weight, more than 0.003% by weight, more than 0.005% by weight, more than 0.01% by weight, more than 0.02% by weight, more than 0.03% by weight, more than 0.05% by weight, more than 0.1 wt%, more than 0.2% by weight and / or less than 10% by weight, less than 9% by weight, less than 8% by weight, less than 7% by weight, less than 6% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, less than 1% by weight, less than 0.9% by weight, less than 0.8% by weight, less than 0.7% by weight, less than 0.6% by weight, less than 0.5% by weight, and less than 0.4% by weight. In a very preferred embodiment, the polyvinylpyrrolidone is present in a ready-to-use composition at a concentration of more than 0.0001% by weight, preferably more than 0.00015% by weight, more preferably more than 0.0002% by weight and / or less than 10% by weight, preferably less than 5% by weight, and more preferably less than 2% by weight.

[0098] In certain embodiments of the present invention, the ready-to-use compositions provided herein comprise an N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, having a weight-average molecular weight in the range of 3,000 to 700,000 g / mol, preferably 5,000 to 500,000 g / mol, more preferably 7,500 to 250,000 g / mol, and even more preferably 8,000 to 100,000 g / mol; wherein the N-vinylpyrrolidone polymer has a concentration in the range of 0.0001 to 10% by weight, preferably 0.00015 to 5% by weight, and more preferably 0.0002 to 3% by weight, based on the total weight of the composition. In certain preferred embodiments, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a concentration in the ready-to-use composition of more than 0.0001% by weight, more than 0.0002% by weight, more than 0.0003% by weight, more than 0.0005% by weight, more than 0.001% by weight, more than 0.002% by weight, more than 0.003% by weight, more than 0.005% by weight, more than 0.01% by weight, more than 0.02% by weight, more than 0.03% by weight, more than 0.05% by weight, more than 0.1% by weight, more than 0.2% by weight and / or less than 10% by weight, less than 9% by weight, less than 8% by weight, less than 7% by weight, less than 6% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, less than 1% by weight, less than 0.9% by weight, less than 0.8% by weight, less than 0.7% by weight, less than 0.6% by weight, less than 0.5% by weight, and less than 0.4% by weight. In a very preferred embodiment, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, is present in a ready-to-use composition at a concentration of more than 0.0001% by weight, preferably more than 0.00015% by weight, more preferably more than 0.0002% by weight and / or less than 10% by weight, preferably less than 5% by weight, and more preferably less than 2% by weight.

[0099] In certain embodiments of the present invention, the ready-to-use compositions provided herein comprise an N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, having a weight-average molecular weight in the range of 700,000 to 2,500,000 g / mol, preferably in the range of 750,000 to 2,250,000 g / mol, more preferably in the range of 850,000 to 2,000,000 g / mol, and even more preferably in the range of 1,000,000 to 1,800,000 g / mol; wherein the N-vinylpyrrolidone polymer has a concentration in the range of 0.0001 to 10% by weight, preferably in the range of 0.00015 to 5% by weight, and more preferably in the range of 0.0002 to 3% by weight, based on the total weight of the composition. In certain preferred embodiments, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a concentration in the ready-to-use composition of more than 0.0001% by weight, more than 0.0002% by weight, more than 0.0003% by weight, more than 0.0005% by weight, more than 0.001% by weight, more than 0.002% by weight, more than 0.003% by weight, more than 0.005% by weight, more than 0.01% by weight, more than 0.02% by weight, more than 0.03% by weight, more than 0.05% by weight, more than 0.1 wt%, more than 0.2% by weight and / or less than 10% by weight, less than 9% by weight, less than 8% by weight, less than 7% by weight, less than 6% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, less than 1% by weight, less than 0.9% by weight, less than 0.8% by weight, less than 0.7% by weight, less than 0.6% by weight, less than 0.5% by weight, and less than 0.4% by weight. In a very preferred embodiment, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a concentration of more than 0.0001% by weight, preferably more than 0.00015% by weight, and more preferably more than 0.0002 w in the ready-to-use composition.

[0100] In certain embodiments of the present invention, the ready-to-use compositions provided herein comprise an N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, having a weight-average molecular weight of 500 to 50,000 g / mol, more preferably 1,000 to 15,000 g / mol, and even more preferably 1,500 to 10,000 g / mol; where the N-vinylpyrrolidone polymer has a concentration in the range of 0.0001 to 10% by weight, preferably 0.00015 to 5% by weight, and more preferably 0.0002 to 3% by weight, based on the total weight of the composition. In certain preferred embodiments, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, has a concentration in the ready-to-use composition of more than 0.0001% by weight, more than 0.0002% by weight, more than 0.0003% by weight, more than 0.0005% by weight, more than 0.001% by weight, more than 0.002% by weight, more than 0.003% by weight, more than 0.005% by weight, more than 0.01% by weight, more than 0.02% by weight, more than 0.03% by weight, more than 0.05% by weight, more than 0.1 wt%, more than 0.2% by weight and / or less than 10% by weight, less than 9% by weight, less than 8% by weight, less than 7% by weight, less than 6% by weight, less than 5% by weight, less than 4% by weight, less than 3% by weight, less than 2% by weight, less than 1% by weight, less than 0.9% by weight, less than 0.8% by weight, less than 0.7% by weight, less than 0.6% by weight, less than 0.5% by weight, and less than 0.4% by weight. In a very preferred embodiment, the N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, is present in a ready-to-use composition at a concentration of more than 0.0001% by weight, preferably more than 0.00015% by weight, more preferably more than 0.0002% by weight and / or less than 10% by weight, preferably less than 5% by weight, and more preferably less than 2% by weight.

[0101] In a preferred embodiment, a ready-to-use composition is provided herein, wherein the base fluid 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, methoxyethanolglycerol, and mixtures thereof, preferably selected from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol, glycerol, and mixtures thereof; and the amount of alcohol is in the range of 10 to 80% by weight (based on the total weight of the composition), preferably 30 to 70% by weight. In certain embodiments, the amount of alcohol is in the range of 10 to 45% by weight (based on the total weight of the composition).

[0102] In a very preferred embodiment, the ready-to-use composition has an electrical conductivity at 25°C of less than 100 μS / cm, preferably less than 50 μS / cm, more preferably less than 25 μS / cm, even more preferably less than 10 μS / cm, even more preferably less than 5 μS / cm, and most preferably less than 2 μS / cm, where the electrical conductivity is measured after optionally aging the heat transfer fluid at 90°C for 14 days in the presence of an aluminum substrate (EN AC-AlSi10Mg(a)T6, DIN EN 1706) using the test procedure described in the Experiments section.

[0103] In a preferred embodiment, the kinematic viscosity of the ready-to-use composition, as measured at 20°C according to ASTM standard test method D445-19a, is 0.1 to 100 mm². 2 Range of / s, preferably 0.5 to 50 mm 2 Range of / s, more preferably 1 to 10 mm 2It is within the range of / s.

[0104] concentrate In preferred embodiments of the present invention, the compositions described herein are provided in the form of concentrates suitable for preparing the ready-to-use compositions described herein.

[0105] In preferred embodiments, the concentrate is suitable for preparing the ready-to-use compositions described herein by adding water and / or alcohol; preferably by adding water, monoethylene glycol, monopropylene glycol, 1,3-propanediol and / or glycerol; most preferably by adding water. In very preferred embodiments, the concentrate is suitable for preparing the ready-to-use compositions by adding water and / or alcohol alone, preferably by adding water, monoethylene glycol, monopropylene glycol, 1,3-propanediol and / or glycerol alone, most preferably by adding water alone (i.e., no other components are needed to prepare the ready-to-use compositions described herein from the concentrate).

[0106] Embodiments of the present invention provide concentrates as defined herein, where the concentration of N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, is greater than 0.01% by weight, preferably greater than 0.05% by weight, more preferably greater than 0.5% by weight and / or less than 10% by weight, preferably less than 5% by weight, and more preferably less than 2% by weight (based on the total weight of the composition).

[0107] In preferred embodiments, a concentrate as defined herein is provided in which the concentration of N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, is in the range of 0.01 to 10% by weight, preferably 0.05 to 5% by weight, and more preferably 0.1 to 2% by weight (based on the total weight of the composition).

[0108] In preferred embodiments, the concentrate comprises a basic fluid as defined herein and an N-vinylpyrrolidone polymer as defined herein, preferably polyvinylpyrrolidone, wherein the concentration of the N-vinylpyrrolidone polymer is greater than 0.01% by weight (based on the total weight of the composition), preferably greater than 0.1% by weight, more preferably greater than 0.5% by weight, and greater than 80% by weight, preferably greater than 85% by weight, preferably greater than 90% by weight of the concentrate is alcohol, preferably an alcohol selected from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol and glycerol, most preferably monoethylene glycol.

[0109] In a preferred embodiment, the concentrate comprises a basic fluid as defined herein and an N-vinylpyrrolidone polymer as defined herein, preferably polyvinylpyrrolidone, wherein the concentration of the N-vinylpyrrolidone polymer is greater than 0.01% by weight, preferably greater than 0.1% by weight, more preferably greater than 0.5% by weight (based on the total weight of the composition), and more than 80% by weight, preferably more than 85% by weight of the concentrate is water.

[0110] Preparation method In another aspect of the present invention: (i) a step of providing a basic fluid as defined herein, (ii) A step of providing an N-vinylpyrrolidone polymer as defined herein, preferably polyvinylpyrrolidone, (iii) a step of optionally providing one or more additional additives as defined herein, A method for preparing a coolant composition as defined herein is provided, comprising the steps of (iv) combining the basic fluid of step (i) with the N-vinylpyrrolidone polymer of step (ii) and one or more optional additional additives of step (iii) to obtain a composition.

[0111] The order of compound addition is not particularly limited according to the present invention.

[0112] In another aspect of the present invention, (i) a step of providing a concentrate as defined herein, (ii) A step of providing water, alcohol or a mixture thereof, (iii) a step of optionally providing one or more additional additives as defined herein, A method for preparing a ready-to-use composition as defined herein is provided, comprising the steps of (iv) combining the concentrate of step (i) with water, alcohol or a mixture thereof of step (ii) and one or more optional additional additives of step (iv) to obtain a ready-to-use composition. In a preferred embodiment, step (iv) comprises combining more than 20% by weight of water (based on the weight of the concentrate), alcohol or a mixture thereof, preferably more than 30% by weight, or more than 50% by weight of water, alcohol or a mixture thereof.

[0113] In a preferred embodiment, the following steps are taken: (i) a step of providing a concentrate as defined herein, (ii) A step of providing water, alcohol or a mixture thereof, A method for preparing a ready-to-use composition as defined herein is provided, comprising the step of (iii) combining the concentrate of step (i) with water, alcohol or a mixture thereof in step (ii) to obtain a ready-to-use composition. In a preferred embodiment, step (iii) comprises combining more than 50% by weight (based on the weight of the concentrate) of water, alcohol or a mixture thereof, preferably more than 100% by weight, more than 150% by weight and more than 200% by weight or more than 500% by weight of water, alcohol or a mixture thereof.

[0114] In accordance with 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.

[0115] others In embodiments of the present invention, the coolant composition defined herein, preferably a ready-to-use composition, has a pH between 3 and 8, preferably between 3.5 and 7.5, and more preferably between 4 and 7.

[0116] In embodiments of the present invention, the coolant composition as defined herein, preferably a ready-to-use composition, has a weight ratio of N-vinylpyrrolidone polymer, preferably polyvinylpyrrolidone, to the alcohol contained in the base fluid of less than 0.01, preferably less than 0.001, and most preferably less than 0.0001.

[0117] Use / method In another aspect of the present invention, an electrical system is provided, preferably selected from the group consisting of solar systems, fuel cells, electric motors, generators, batteries, telephone transmission stations, radio and television broadcasting stations, relay stations, electric heating or cooling devices, charging stations and powerful lasers / beamers, more preferably from fuel cells, wherein the electrical system further comprises a coolant composition as defined herein, preferably a ready-to-use composition as described herein. The electrical system preferably comprises aluminum in contact with the coolant composition as defined herein. In another aspect, the present invention provides the use of an N-vinylpyrrolidone polymer as defined herein, preferably polyvinylpyrrolidione, in a low-electrical conductivity coolant composition comprising water and alcohol as an inhibitor of electrical conductivity and / or antioxidant.

[0118] In another embodiment, the present invention is • For suppressing the formation of glycolate or formate ions in alcohol and water-based coolants, preferably in alcohol and water-based coolants in direct contact with electrical systems containing aluminum, and preferably in monoethylene glycol and water-based coolants, or • To maintain low electrical conductivity of alcohol and water-based coolants, preferably in direct contact with electrical systems containing aluminum, This specification provides for the use of N-vinylpyrrolidone polymers, preferably polyvinylpyrrolidones, as defined herein.

[0119] Another aspect of the present invention provides for the use of the coolant compositions described herein, preferably ready-to-use compositions, as a heat transfer fluid or coolant, preferably as a heat transfer fluid or coolant in an electrical system, more preferably as a heat transfer fluid or coolant 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 broadcasting stations, relay stations, and electric heating or cooling devices, preferably as a heat transfer fluid or coolant in a fuel cell or power electronics.

[0120] In another aspect of the present invention, a. An electrical system containing aluminum, 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 broadcasting stations, relay stations, and electric heating or cooling devices, preferably an electrical system such as a fuel cell or power electronics, which generates heat. b. A step of bringing a coolant composition described herein, preferably a ready-to-use composition described herein, into contact with the system of step a, c. A step of transferring heat from the system to the coolant composition, d. A step of passing the composition through a heat exchanger, A method for heat exchange is provided, comprising the step of transferring heat from a coolant composition. [Examples]

[0121] The remarkable behavior of the coolant compositions according to the present invention, specifically their electrical conductivity during aging, even in the presence of aluminum, was demonstrated by immersing aluminum test specimens in various compositions or comparative compositions according to the present invention, as described below, and by aging the compositions at 90°C for 14 days.

[0122] Various amounts of polyvinylpyrrolidone (Luvitec K17:M w = 9,000 g / mol, Luvitec K30a:M w = 40,000 g / mol, Luvitec K30b:M w = 50,000 g / mol and Luvitec K90:M w Fourteen compositions (Examples 2-15) were prepared by adding 1,400,000 g / mol of MEG to a 33 volume% MEG composition in UPW (ultrapure water).

[0123] Example 1 is a blank composition consisting of 33 volume% MEG in UPW, i.e., it does not contain polyvinylpyrrolidone.

[0124] The compositions prepared in Examples 1-15 were treated with DOWEX Marathon MR3 (now Amberlite MB20 HOH), i.e., a mixed-bed ion exchange resin, to remove all residual ionic compounds from the prepared compositions. For this purpose, the compositions were stirred for 3 hours using 0.5 w% DOWEX Marathon MR3 (now Amberlite MB20 HOH) at room temperature. The ion exchanger was removed by filtration after 3 hours.

[0125] The pH and electrical conductivity (eConduc) of the compositions treated in this manner were measured (measurements "before aging") and listed in the table below. Then, 100 mL glass bottles were rinsed with UPW and dried overnight at 90°C. Aluminum (EN AC-AlSi10Mg(a)T6, DIN EN 1706) coupons were polished using P240 sanding paper, rinsed with UPW and acetone, dried at 100°C for 1 hour, and weighed (new coupons). The coupons were placed in the bottles, and 100 mL of the compositions from Examples 1-15 were added to the bottles. The bottles were then placed in a furnace at 90°C. After 14 days, the bottles were removed from the furnace, and the electrical conductivity and pH of the aged compositions were measured. The glycolate and formate concentrations in the aged compositions were determined by ion chromatography. All coupons were gently cleaned with water and a soft-bristled brush, dried, and weighed (coupons AT). Finally, all coupons were chemically cleaned by placing them in a 4:1 mixture of HNO3:UPW for 10 minutes. The coupons were further cleaned with water and a soft-bristled brush, dried at 100°C for 1 hour, and weighed (coupon CC). The weight change of aluminum coupons due to aging was calculated using the following formula: Δm(mg) = mass of new coupon (mg) - mass of coupon CC (mg). The experimental results are shown in Table 1.

[0126] [Table 1]

[0127] As can be seen from the results above, the compositions according to the present invention using polyvinylpyrrolidione (Examples 2-15) surprisingly and unexpectedly exhibit low electrical conductivity and very limited glycol degradation during aging in the presence of aluminum.

Claims

1. A coolant composition comprising a basic fluid and an N-vinylpyrrolidone polymer, wherein the composition has an electrical conductivity of less than 100 μS / cm at 25°C. The aforementioned basic fluid consists of water and alcohol. The alcohol is present in an amount ranging from 10% to 99.5% by weight based on the weight of the base fluid. It is located, The composition contains more than 75% by weight of a basic fluid based on the total weight of the composition, Coolant composition in which the amount of inorganic compound is less than 100 ppm based on the total weight of the composition thing.

2. The coolant composition according to claim 1, having an electrical conductivity of less than 50 μS / cm at 25°C.

3. The coolant composition according to claim 1 or 2, 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.

4. The coolant composition according to claim 1 or 2, wherein the alcohol is present in an amount ranging from 30 to 70% by weight based on the weight of the base fluid.

5. The coolant composition according to claim 1 or 2, wherein the N-vinylpyrrolidone polymer has a weight-average molecular weight in the range of 500 to 2,500,000 g / mol.

6. The coolant composition according to claim 5, wherein the N-vinylpyrrolidone polymer has a weight-average molecular weight in the range of 500 to 50,000 g / mol.

7. The coolant composition according to claim 1 or 2, comprising one or more additional additives selected from the group consisting of thiazole, triazole, polyolefin, polyalkylene oxide, silicone oil, mineral oil, silicate ester, aliphatic monocarboxylic acid, aliphatic dicarboxylic acid, and aliphatic tricarboxylic acid.

8. The coolant composition according to claim 1 or 2, wherein the amount of inorganic compound is less than 50 ppm.

9. A coolant composition according to claim 1, provided in the form of a ready-to-use composition that is a heat transfer fluid, - The concentration of the N-vinylpyrrolidone polymer is in the range of 0.0001 to 10% by weight based on the total weight of the composition. and - A coolant composition comprising more than 90% by weight of a basic fluid based on the total weight of the composition.

10. The coolant composition according to claim 9, - The concentration of the N-vinylpyrrolidone polymer is in the range of 0.00015 to 5% by weight based on the total weight of the composition. and - A coolant composition comprising more than 95% by weight of a basic fluid based on the total weight of the composition.

11. The coolant composition according to claim 1, having a pH between 3 and 8.

12. The coolant composition according to any one of claims 9 to 11, wherein the basic fluid consists of water and an alcohol selected from the group consisting of monoethylene glycol, monopropylene glycol, 1,3-propanediol, glycerol, and mixtures thereof, and the alcohol is present in an amount ranging from 30 to 70% by weight based on the weight of the basic fluid.

13. The kinematic viscosity at 20°C, measured according to the ASTM standard test method D445-19a, is between 0.1 and 100 mm². ２ A coolant composition according to any one of claims 9 to 11, wherein the coolant is in the range of / s.

14. The coolant composition according to claim 11, provided in the form of a concentrate suitable for preparing the composition according to claim 11 by adding only water and / or alcohol, which is ready to use.

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