Coolant composition

Abstract

An object of the present invention is to provide a coolant composition for an electric vehicle from which fluoride ions are sufficiently removed.SOLUTION: The present invention relates to a coolant composition for electric vehicle, comprising a fluoride scavenger consisting of calcium carbonate, calcium nitrate, or a mixture thereof, wherein the content of fluoride ions is 80ppm or less, the pH is 6 to 9, and the conductivity is 250 μ S / cm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to coolant compositions for electric vehicles. [Background technology]

[0002] Electric vehicles use coolants to cool the battery and other components. Components of materials used in the manufacturing of cooling system components can be contaminated into the coolant. For example, during the manufacturing process of aluminum heat exchangers used in battery coolers, residues of flux used in brazing can dissolve in the coolant, causing fluoride ions (also called fluorine ions) in the flux to be contaminated into the coolant. Fluoride ions are corrosive to metals, and there is concern that they may cause rust in the metals of the cooling system. Furthermore, when the coolant has an alkaline pH, there is also concern that the metals of the cooling system may rust.

[0003] Batteries for battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) require high electrical resistance. When cooling components that require high electrical resistance, it is preferable to use a coolant with low electrical conductivity. However, typical engine coolants have high electrical conductivity. Furthermore, rust inhibitors are typically added to coolants. Reducing the amount of rust inhibitor to lower the conductivity of the coolant reduces the coolant's rust prevention capabilities.

[0004] As such, coolants for electric vehicles are required to have high corrosion resistance and low electrical conductivity. To achieve high corrosion resistance, the coolant must contain a sufficiently low amount of fluoride ions, which are corrosive to metals, and have a neutral pH.

[0005] Here, known technologies for removing fluorine from wastewater include those that use calcium compounds such as calcium nitrate, calcium hydroxide, and calcium carbonate (Patent Documents 1 to 3). However, in the fluorine removal methods for wastewater treatment disclosed in Patent Documents 1 to 3, the efficiency of fluorine removal and reuse is pursued. For this reason, even if conventional fluorine removal technologies are applied to coolants, they cannot satisfy the properties required for coolants for electric vehicles. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-212471 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-342698 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-246267 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, even if conventional fluorine removal techniques are applied to coolants, the properties required for coolants for electric vehicles cannot be satisfied. Therefore, an object of the present invention is to provide a coolant composition for electric vehicles from which fluoride ions are sufficiently removed. [Means for solving the problem]

[0008] The present inventors have discovered that by adding calcium carbonate, calcium nitrate, or a mixture thereof as a fluoride remover, it is possible to maintain a neutral pH and low electrical conductivity in a coolant composition while sufficiently removing fluoride ions, and have completed the present invention.

[0009] That is, the gist of the present invention is as follows. (1) A coolant composition for electric vehicles, comprising a fluoride remover consisting of calcium carbonate, calcium nitrate, or a mixture thereof, having a fluoride ion content of 80 ppm or less, a pH of 6 to 9, and an electrical conductivity of 250 μS / cm or less. (2) The coolant composition for an electric vehicle according to (1), wherein the content of the calcium carbonate is 3 g / L to 50 g / L relative to the components other than the fluorine removing agent in the coolant composition, and the content of the calcium nitrate is 3 g / L to 60 g / L relative to the components other than the fluorine removing agent in the coolant composition. (3) The coolant composition for an electric vehicle according to (1) or (2) above, wherein the fluorine removing agent comprises the calcium carbonate or calcium nitrate. (4) The electric vehicle coolant composition according to any one of (1) to (3) above, which contains a base, and the base is at least one alcohol selected from dihydric alcohols, trihydric alcohols, and glycol monoalkyl ethers, and / or water. (5) A concentrated coolant composition for obtaining the coolant composition for an electric vehicle according to any one of (1) to (4) above, which is used by diluting with water. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a coolant composition for an electric vehicle from which fluoride ions have been sufficiently removed. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will now be described in detail.

[0012] The coolant composition for electric vehicles (hereinafter also referred to as the coolant composition) of the present invention contains a fluoride remover consisting of calcium carbonate, calcium nitrate, or a mixture thereof. By containing the fluoride remover, the coolant composition of the present invention has the properties required for a coolant composition for electric vehicles. Specifically, the coolant composition of the present invention has a fluoride ion content of 80 ppm or less, a pH of 6 to 9, and an electrical conductivity of 250 μS / cm or less.

[0013] In the coolant compositions of the present invention, calcium carbonate, calcium nitrate, or a mixture thereof is used as the fluoride remover. In one embodiment, the fluoride remover comprises calcium carbonate or calcium nitrate.

[0014] In the coolant composition of the present invention, the content of the fluorine removing agent can be appropriately set depending on the properties desired for the coolant composition.

[0015] In the coolant composition of the present invention, the content of calcium carbonate may be 3 g / L to 50 g / L relative to the components other than the fluoride removing agent in the coolant composition. When the content of calcium carbonate is 3 g / L or more, fluoride ions are sufficiently removed from the coolant composition. This improves the corrosion prevention properties of the coolant composition. When the content of calcium carbonate is 50 g / L or less, an increase in the pH of the coolant composition is suppressed. This improves the corrosion prevention properties of the coolant composition.

[0016] In the coolant composition of the present invention, the content of calcium nitrate may be 3 g / L to 60 g / L relative to the components other than the fluoride remover in the coolant composition. When the content of calcium nitrate is 3 g / L or more, fluoride ions are sufficiently removed from the coolant composition. This improves the corrosion resistance of the coolant composition. When the content of calcium nitrate is 60 g / L or less, an increase in the electrical conductivity of the coolant composition is suppressed.

[0017] In one embodiment, the fluoride removing agent is a mixture of calcium carbonate and calcium nitrate. In this embodiment, too, the content of the fluoride removing agent can be appropriately set depending on the desired properties of the coolant composition. In this embodiment, for example, the content of calcium carbonate may be 3 g / L to 50 g / L relative to the components other than the fluoride removing agent in the coolant composition, and the content of calcium nitrate may be 3 g / L to 60 g / L relative to the components other than the fluoride removing agent in the coolant composition. In another embodiment, the content of calcium carbonate may be 10 g / L to 30 g / L relative to the components other than the fluoride removing agent in the coolant composition, and the content of calcium nitrate may be 10 g / L to 35 g / L relative to the components other than the fluoride removing agent in the coolant composition.

[0018] When the fluoride removing agent is a mixture of calcium carbonate and calcium nitrate, the mass ratio of calcium carbonate to calcium nitrate is usually 1:100 to 100:1, and may be 1:10 to 10:1.

[0019] The coolant composition of the present invention may contain a base. The content of the base is usually 1 to 95% by mass, and may be 25 to 60% by mass, based on the coolant composition.

[0020] As the base, for example, at least one alcohol selected from dihydric alcohols, trihydric alcohols and glycol monoalkyl ethers and / or water can be used.

[0021] Examples of dihydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, and hexylene glycol.

[0022] Examples of trihydric alcohols include glycerin, trimethylolethane, trimethylolpropane, 5-methyl-1,2,4-heptanetriol, and 1,2,6-hexanetriol.

[0023] Examples of glycol monoalkyl ethers include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and tetraethylene glycol monobutyl ether.

[0024] In one embodiment, the alcohols are ethylene glycol, propylene glycol, and 1,3-propanediol from the viewpoints of ease of handling, cost, and availability.

[0025] The base may be a mixture of water and alcohols. When a mixture of water and alcohols is used as the base, the ratio of water to alcohols in the base is usually 20:80 to 90:10, or may be 40:60 to 75:25, from the viewpoint of avoiding the occurrence of a flash point.

[0026] If antifreeze properties are not required, the base may be water alone.

[0027] In one embodiment, the base is a mixture of a dihydric alcohol and water, and may be a mixture of ethylene glycol and water.

[0028] The coolant composition of the present invention may optionally contain one or more other additives in addition to the base and fluorine remover, provided that the effects of the present invention are not impaired. Examples of such additives include, but are not limited to, rust inhibitors (such as carboxylic acids, nitrates, nitrites, thiazoles, molybdates, and borates), dyes, bittering agents, pH adjusters, and antifoaming agents. The total content of the other additives is typically 10% by mass or less, and may be 5% by mass or less, based on the coolant composition.

[0029] The coolant composition of the present invention has a sufficiently low fluoride ion content of 80 ppm or less. The coolant composition of the present invention has excellent corrosion prevention properties because it has a sufficiently low content of fluoride ions, which are ions corrosive to metals.

[0030] The coolant composition of the present invention has a pH of 6 to 9 (that is, 6.0 or higher and 9.0 or lower). When the coolant composition has a pH of 6 to 9, it has excellent corrosion prevention properties.

[0031] The coolant composition of the present invention has a sufficiently low electrical conductivity of 250 μS / cm or less at 25° C. The electrical conductivity of the coolant composition can be measured as described in the examples.

[0032] The method for producing the coolant composition of the present invention is not particularly limited, and a conventional production method can be used. For example, the coolant composition of the present invention can be produced by preparing a mixture containing the base and, if necessary, other additives, adding a fluoride removing agent to the mixture, and stirring the mixture uniformly. The coolant composition of the present invention can also be produced by mixing the base, the fluoride removing agent, and, if necessary, other additives, and stirring the mixture uniformly.

[0033] The present invention also includes a concentrated coolant composition for obtaining the above-mentioned coolant composition. The concentrated coolant composition of the present invention contains the above-mentioned base and fluoride removing agent, and optionally contains other additives. The concentrated coolant composition of the present invention is used by diluting it with water, for example, 1.1 to 5 times by mass. The concentrated coolant composition of the present invention may contain or not contain water. Note that when the concentrated coolant composition of the present invention contains water, the content of water is less than the content of water in the coolant composition.

[0034] The coolant composition of the present invention has excellent corrosion prevention properties because fluoride ions have been sufficiently removed and the pH is neutral. Furthermore, the coolant composition of the present invention has low electrical conductivity. Therefore, the coolant composition of the present invention is suitable for use as a coolant composition for electric vehicles. The electric vehicle to which the coolant composition of the present invention can be applied may be any vehicle equipped with a traction motor, and examples thereof include battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). The coolant composition of the present invention can be used to cool heat-generating devices of electric vehicles (e.g., batteries, inverters, radiators, oil coolers, heater cores, etc.). [Example]

[0035] The present invention will be described in more detail below using examples, although the technical scope of the present invention is not limited to these examples.

[0036] <Preparation of Coolant Composition> Each of the coolant compositions of Examples 1 to 4 and Comparative Examples 1 to 4 was prepared by adding calcium carbonate or calcium nitrate (fluoride remover) in the amount shown in Table 1 to a commercially available coolant (drive battery coolant manufactured by Toyota Motor Corporation) containing ethylene glycol and water as a base. The content (g / L) of the fluoride remover is the amount relative to the components other than the fluoride remover in the coolant composition (i.e., the commercially available coolant used).

[0037] <Evaluation of Coolant Compositions> The coolant compositions of Examples 1 to 4 and Comparative Examples 1 to 4 were measured for fluoride ion content, pH, and electrical conductivity as follows.

[0038] Fluoride ion content The fluoride ion content was measured by a flask combustion method using an ion chromatograph manufactured by Shimadzu Corporation. The fluoride ion content is measured on a mass basis (ppm by mass).

[0039] pH The pH was measured at 25°C using a pH meter (Yokogawa Electric Corporation, Personal pH Meter PH71).

[0040] conductivity The conductivity was measured at 25°C using a conductivity meter (Yokogawa Electric Corporation, personal SC meter SC72, ​​detector SC72SN-11 (for pure water)).

[0041] Table 1 shows the type and content of the fluorine removing agent and the evaluation results for the coolant compositions of Examples 1 to 4 and Comparative Examples 1 to 4.

[0042] [Table 1]

[0043] As shown in Table 1, when the fluoride removing agent was calcium carbonate (Examples 1 and 2 and Comparative Examples 1 and 2), the pH of the coolant composition increased as the calcium carbonate content increased. This is thought to be because the carbon dioxide gas generated by the dissolution of calcium carbonate was discharged outside the liquid, leaving only the calcium content in the liquid.

[0044] As shown in Table 1, when the fluoride removing agent was calcium nitrate (Examples 3 and 4 and Comparative Examples 3 and 4), the conductivity of the coolant composition increased as the calcium nitrate content increased. This is thought to be because, unlike carbonate ions generated by carbon dioxide gas, nitrate ions exist as ions in the liquid and increase the conductivity.

Claims

1. containing a fluoride remover consisting of calcium carbonate, calcium nitrate or a mixture thereof; The fluoride ion content is 80 ppm or less, pH is 6 to 9, The conductivity is 250 μS / cm or less. Electric vehicle coolant composition.

2. the content of the calcium carbonate is 3 g / L to 50 g / L relative to the components other than the fluoride removing agent in the coolant composition; the content of the calcium nitrate is 3 g / L to 60 g / L relative to the components other than the fluorine removing agent in the coolant composition; The electric vehicle coolant composition of claim 1.

3. 3. The electric vehicle coolant composition according to claim 1, wherein said fluorine removing agent comprises said calcium carbonate or said calcium nitrate.

4. 3. The electric vehicle coolant composition according to claim 1, further comprising a base, wherein the base is at least one alcohol selected from the group consisting of dihydric alcohols, trihydric alcohols, and glycol monoalkyl ethers, and / or water.

5. 3. A concentrated coolant composition for obtaining the coolant composition for an electric vehicle according to claim 1 or 2, which is used by diluting with water.

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