Heat storable substance, heat storage agent, heat transport medium, and semi-clathrate hydrate

Abstract

To provide a heat storable substance which can form a semi-clathrate hydrate without presence of a halogen element.SOLUTION: Provided is a heat storable substance comprising an ionic material and water, in which the ionic material includes at least one cation selected from a group consisting of tri-n-butyl n-hexyl ammonium cation, tri-n-butyl n-pentyl phosphonium cation, and tri-n-butyl n-hexyl phosphonium cation, and at least one anion selected from a group consisting of acetate ions, propionate ions, butyrate ions, valerate ions, isovalerate ions, and acrylate ions.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a heat storage material, a heat storage agent, a heat transport medium, and a semiclathrate hydrate. [Background technology]

[0002] A heat storage material with a large latent heat is useful because it can be used as a heat storage agent or a heat transport medium. Semiclathrate hydrate is known as a heat storage material. A clathrate hydrate is a crystal formed by encapsulating a guest molecule inside a cage-like structure formed by water molecules through hydrogen bonds, and a semiclathrate hydrate is a type of clathrate hydrate. A semiclathrate hydrate is a crystalline material in which an anion is incorporated into a part of the cage-like structure formed by water molecules, and can be generated from an aqueous solution of an ionic substance. Since a semiclathrate hydrate is composed of hydrogen bonds of hydration water, it has a large latent heat. Therefore, the semiclathrate hydrate can be used as a heat storage agent, etc. In addition, a heat storage material containing an ionic substance that forms a semiclathrate hydrate can also be used as a heat storage agent, etc.

[0003] For example, Patent Document 1 describes a cooling agent containing tri-n-butyl alkyl ammonium salt and water as a heat storage material. Specific experimental data on the melting temperature and latent heat of a hydrate in which tri-n-butyl alkyl ammonium salt tri-n-butyl pentyl ammonium bromide (TBPAB) is used as a heat storage main agent and tetra-n-butyl ammonium fluoride is mixed as a supercooling prevention agent is disclosed. Specific experimental data on the melting temperature and latent heat of a hydrate in which tetra-n-butyl ammonium bromide (TBAB) is used as a heat storage main agent and tri-n-butyl pentyl ammonium bromide (TBPAB) or tri-n-butyl isopentyl ammonium bromide is mixed as a melting point adjuster is disclosed.

[0004] Patent Document 2 describes a heat storage material, a heat storage agent, etc., containing a tri-n-butyl alkyl ammonium salt and water. Specific experimental data on the melting temperature and latent heat of each hydrate of TBPAB, tri-n-butyl-n-pentyl ammonium chloride (TBPACl), and a mixture of TBPAB and TBAB, among the tri-n-butyl alkyl ammonium salts, is disclosed. Non-Patent Document 1 discloses the experimental results of the solid-liquid phase change of RBu3NBr-H2O (tri-n-butylalkylammonium bromide and water, R represents an alkyl group, and Bu represents an n-butyl group). Non-Patent Document 2 discloses the experimental results of the solid-liquid phase change of (n-C4H9)3RNF+water (tri-n-butylalkylammonium fluoride and water, R represents an alkyl group). Non-Patent Document 3 discloses the experimental results of the solid-liquid phase change of (n-C4H9)4NOOCR+water (tetra-n-butylammonium carboxylate+water). Non-Patent Document 4 discloses the results of experiments on the latent heat and crystal structure analysis of semiclathrate hydrate formed by tri-n-butylalkylphosphonium bromide. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-161894 A [Patent Document 2] JP 2007-186667 A [Non-patent literature]

[0006] [Non-Patent Document 1] Yu. A. Dyadin et al., "CLATHRATE FORMATION IN WATER-PERALKYLONIUM SALTS SYSTEM", Journal of Inclusion Phenomena 2, 61-72 (1984). [Non-Patent Document 2] H. Nakayama et al., "Hydrates of Organic Compounds. II. The Effect of Alkyl Groups on the Formation of Quaternary Ammonium Fluoride Hydrates", Bulletin of the Chemical Society of Japan, Vol.49, No.5, (1976), pp.1254-1256

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[0007] On the other hand, since the shape and size of the guest molecule must match the shape of the hydrogen bond network of water molecules, semiclathrate hydrate may not be formed depending on the type of cation and / or anion or their combination. In fact, Non-Patent Document 1 describes that in RBu3NBr-H2O, when the alkyl group R is a methyl group, an ethyl group, or an n-hexyl group, clathrate formation did not occur. In addition, Non-Patent Document 2 describes that in (n-C4H9)3RNF+water, when the alkyl group R is an n-hexyl group or an n-heptyl group, clathrate formation does not occur.

[0008] Thus, the structure of the cation and anion has a large effect on the formation of the clathrate. On the other hand, as mentioned above, many of the semiclathrate hydrates reported so far contain halogen elements. When using semiclathrate hydrates as heat storage agents, etc., it is desirable that they do not contain halogen elements from the viewpoint of reducing environmental load. However, studies on substances that can form semiclathrate hydrates regardless of the presence of halogen elements have not been conducted sufficiently so far, except for the case of tetra-n-butylammonium as the cation in Non-Patent Document 3 or the case of tetra-n-butylphosphonium as the cation.

[0009] The present disclosure solves the above problems and provides a heat storage material capable of forming a semiclathrate hydrate regardless of the presence of a halogen element. Also, the present disclosure provides a semiclathrate hydrate formed regardless of the presence of a halogen element. Furthermore, the present disclosure provides a heat storage agent having high performance. In addition, the present disclosure provides a heat transport medium having high performance. [Means for solving the problem]

[0010] The present disclosure relates to A heat storage material comprising an ionic material and water, The ionic substance is Tri-n-butyl, n-hexylammonium cation, tri-n-butyl, n-pentylphosphonium cation, and tri-n-butyl, n-hexylphosphonium cation At least one cation selected from the group consisting of: At least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion; A heat storage material comprising Regarding.

[0011] The present disclosure also relates to a heat storage agent containing the above heat storage material. Furthermore, the present disclosure relates to a heat transport medium containing the above-mentioned heat storage material.

[0012] In addition, the present disclosure provides At least one cation selected from the group consisting of tri-n-butyl, n-hexyl ammonium cation, tri-n-butyl, n-pentyl phosphonium cation, and tri-n-butyl, n-hexyl phosphonium cation; At least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion; and semiclathrate hydrate containing water of hydration. Regarding. Effect of the Invention

[0013] According to the present disclosure, a heat storage material capable of forming a semiclathrate hydrate regardless of the presence of a halogen element is provided. Also, according to the present disclosure, a semiclathrate hydrate formed regardless of the presence of a halogen element is provided. Furthermore, according to the present disclosure, a heat storage agent having high performance is provided. In addition, according to the present disclosure, a heat transport medium having high performance is provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will be described in detail below, but is not limited to the following description. The description of a numerical range such as "XX to YY" or "XX to YY" means a numerical range including the lower and upper limits, unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined.

[0015] (Embodiment 1) <Ammonium-based semi-clathrate hydrate (SCH)> The ammonium-based semiclathrate hydrate according to the first embodiment of the present disclosure includes a tri-n-butyl, n-hexyl ammonium cation, at least one anion selected from the group consisting of acetate, propionate, butyrate, valerate, isovalerate, and acrylate, and hydration water. Hereinafter, semiclathrate hydrate may be abbreviated as "SCH". In addition, tri-n-butyl, n-hexyl ammonium cation may be abbreviated as "N4446". N4446 means that three n-butyl groups having 4 carbon atoms and one n-hexyl group having 6 carbon atoms are bonded to one nitrogen (N) center.

[0016] Moreover, SCH preferably consists of N4446, at least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion, and water of hydration. The inclusion of N4446 and at least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion can be said to include an ionic substance containing the cation and the anion. It can also be said to include an ionic substance composed of the cation and the anion.

[0017] By containing N4446, hydration water, and an anion described below, SCH is formed regardless of the presence of a halogen element. In other words, it is preferable that SCH does not contain a halogen element. The formation of SCH can be confirmed by X-ray crystal structure analysis.

[0018] The content of N4446 in SCH is not particularly limited as long as SCH can be formed, but may be, for example, 20 to 40 mass %.

[0019] In addition, SCH contains water of hydration, which means that it has a large latent heat and can be suitably used as a heat storage agent. The hydration number of SCH is preferably 40.0 or more. The upper limit is not particularly limited, but is preferably, for example, 40.0 to 50.0, and more preferably 42.0 to 50.0. If there is a large amount of water of hydration, the latent heat per mole of SCH ions tends to be large. Here, the term "per mole of SCH ions" refers to the unit amounts of 1 mole of cations and 1 mole of anions contained in the semiclathrate hydrate, and the amount of water of hydration that incorporates these cations and anions into the semiclathrate hydrate. A specific calculation method will be described later. The hydration number can be adjusted by changing the anion, which will be described later. The method for measuring the hydration number will be described later.

[0020] SCH contains at least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion. Among them, at least one anion selected from the group consisting of propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion is preferred, at least one anion selected from the group consisting of propionate ion, butyrate ion, valerate ion, and isovalerate ion is more preferred, and at least one anion selected from the group consisting of butyrate ion, valerate ion, and isovalerate ion is even more preferred. By using the above anions, SCH can be formed without depending on the presence of halogen elements. Furthermore, the latent heat per mole of SCH ions tends to be large.

[0021] The content of the above anions in SCH is not particularly limited as long as SCH can be formed, and may be, for example, 20 to 40 mass %.

[0022] The melting point of SCH is not particularly limited, but is preferably 0.0 to 10.0°C, and more preferably 1.0 to 10.0°C. If the melting point of SCH is 10.0°C or less, it can store heat more suitably when used as a heat storage agent. In addition, in order to make the hardness of SCH suitable, it is more preferably 3.0 to 10.0°C, and particularly preferably 3.0 to 7.0°C. If the melting point of SCH is 3.0°C or more, the hardness of SCH is low and it is easy to become soft. Therefore, when used as a heat storage agent, it can also function as a buffer material. The melting point of SCH can be adjusted by changing the anion. The method for measuring the melting point will be described later.

[0023] The latent heat of SCH is not particularly limited, but from the viewpoint of improving the performance of the heat storage agent when SCH is used as a heat storage agent, etc., it is preferably 180 kJ / kg or more, more preferably 190 kJ / kg or more, even more preferably 200 kJ / kg or more, and particularly preferably 210 kJ / kg or more. The upper limit is not particularly limited, but for example, preferred examples include 180 to 330 kJ / kg, 190 to 330 kJ / kg, 200 to 330 kJ / kg, 210 to 330 kJ / kg, 180 to 220 kJ / kg, 190 to 220 kJ / kg, 200 to 220 kJ / kg, and 210 to 220 kJ / kg. The latent heat of SCH can be adjusted by changing the anion. The measurement method will be described later.

[0024] The latent heat per mole of SCH ions is not particularly limited, but from the viewpoint of improving the performance of the heat storage agent when SCH is used as a heat storage agent, etc., it is preferably 190 kJ / mol or more, more preferably 200 kJ / mol or more, even more preferably 220 kJ / mol or more, particularly preferably 230 kJ / mol or more, and especially preferably 240 kJ / mol or more. The upper limit is not particularly limited, but for example, preferred values ​​include 190 to 270 kJ / mol, 200 to 270 kJ / mol, 220 to 270 kJ / mol, 230 to 270 kJ / mol, and 240 to 270 kJ / mol. The latent heat per mole of SCH can be adjusted by changing the anion. The method for measuring the latent heat per mole will be described later.

[0025] <Heat storage material> The heat storage material according to the first embodiment of the present disclosure includes an ionic material and water. The ionic material includes a tri-n-butyl, n-hexyl ammonium cation and at least one anion selected from the group consisting of acetate ions, propionate ions, butyrate ions, valerate ions, isovalerate ions, and acrylate ions. The ionic material is preferably composed of N4446 and at least one anion selected from the group consisting of acetate ions, propionate ions, butyrate ions, valerate ions, isovalerate ions, and acrylate ions. It is also preferable that the heat storage material is composed of an ionic material and water.

[0026] When the ionic substance contained in the heat storage material contains N4446 and an anion described below, and the heat storage material contains water, the heat storage material can form SCH regardless of the presence of a halogen element. That is, it is preferable that the heat storage material does not contain a halogen element. For example, when the temperature of the heat storage material is higher than the melting point, the hydration water contained in the heat storage material dissociates. Then, by lowering the temperature of the heat storage material to the melting point or lower, at least a part of the water contained in the heat storage material becomes hydration water and forms SCH. That is, SCH can also be said to be a heat storage material.

[0027] The content of N4446 in the heat storage material is not particularly limited as long as it is capable of forming SCH, and may be, for example, 20 to 40 mass %.

[0028] The content of water in the heat storage material is not particularly limited, but is preferably a content that allows SCH to be formed. For example, when the content is 60 to 80 mass %, SCH is easily formed. The water contained in the heat storage material is not particularly limited, and ion-exchanged water, ultrapure water, or the like can be used.

[0029] The heat storage material contains at least one anion selected from the group consisting of acetate ions, propionate ions, butyrate ions, valerate ions, isovalerate ions, and acrylate ions. Among them, at least one anion selected from the group consisting of propionate ions, butyrate ions, valerate ions, isovalerate ions, and acrylate ions is preferred, at least one anion selected from the group consisting of propionate ions, butyrate ions, valerate ions, and isovalerate ions is more preferred, and at least one anion selected from the group consisting of butyrate ions, valerate ions, and isovalerate ions is even more preferred. By using the above anions, the heat storage material can form SCH.

[0030] The content of the above anions in the heat storage material is not particularly limited as long as it is possible to form SCH, and may be, for example, 20 to 40 mass %.

[0031] The melting point of the heat storage material is not particularly limited, but is preferably 0.0 to 10.0°C, and more preferably 1.0 to 10.0°C. When the heat storage material has a melting point of 10.0°C or less, it can store heat more suitably when used as a heat storage agent. In addition, in order to make the hardness of the heat storage material suitable, it is more preferably 3.0 to 10.0°C, and particularly preferably 3.0 to 7.0°C. When the melting point of the heat storage material is 3.0°C or more, the hardness of the heat storage material is low and it is easy to become soft. Therefore, when used as a heat storage agent, it can also function as a buffer material. The melting point of the heat storage material can be adjusted by changing the anion.

[0032] The heat storage material can be used as, for example, a heat storage agent or a heat transport medium. That is, the heat storage material preferably contains the heat storage material of the present disclosure. Also, the heat transport medium preferably contains the heat storage material of the present disclosure.

[0033] <Method of manufacturing semi-clathrate hydrate (SCH)> The method for producing SCH is not particularly limited, but preferably includes, in this order, a preparation step for obtaining tri-n-butyl, n-hexylammonium hydroxide, a neutralization step for neutralizing the obtained tri-n-butyl, n-hexylammonium hydroxide with a carboxylic acid, and a crystallization step for crystallizing the product obtained in the neutralization step. In the preparation step, tri-n-butyl, n-hexyl ammonium hydroxide is obtained. It may be commercially available or may be synthesized by a known method. For example, tri-n-butyl, n-hexyl ammonium hydroxide can be obtained by passing an aqueous solution of tri-n-butyl, n-hexyl ammonium bromide through an anion exchange resin. As an example of an anion exchange resin, IRA402BL(OH)-HG manufactured by Oregano Co. can be mentioned.

[0034] In the neutralization step, tri-n-butyl, n-hexylammonium hydroxide is neutralized with a carboxylic acid. As the carboxylic acid, at least one carboxylic acid selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, isovaleric acid, and acrylic acid can be used, and among them, at least one carboxylic acid selected from the group consisting of propionic acid, butyric acid, valeric acid, isovaleric acid, and acrylic acid is preferred, at least one carboxylic acid selected from the group consisting of propionic acid, butyric acid, valeric acid, and isovaleric acid is more preferred, and at least one carboxylic acid selected from the group consisting of butyric acid, valeric acid, and isovaleric acid is even more preferred.

[0035] The amount of carboxylic acid relative to tri-n-butyl, n-hexylammonium hydroxide is preferably a molar equivalent.

[0036] The method for producing SCH preferably further includes a purification step after the neutralization step. If by-products such as tributylamine are present after the neutralization step, the by-products can be removed by carrying out a purification step. The purification step is not particularly limited, but may be, for example, a step of passing the aqueous solution after the neutralization step through a strong base ion exchange membrane of OH type.

[0037] In the crystallization step, the product obtained in the neutralization step is crystallized. The product obtained in the neutralization step includes the purified product obtained in the purification step. SCH is obtained by crystallization. The crystallization conditions are not particularly limited, and a temperature control means such as a freezer, refrigerator, or thermostatic bath, or a process of continuous crystallization and separation from the residual liquid can be used.

[0038] (Embodiment 2) <Phosphonium-based semiclathrate hydrate (SCH)> The phosphonium-based semiclathrate hydrate of the second embodiment of the present disclosure includes at least one cation selected from the group consisting of tri-n-butyl, n-pentyl phosphonium cation and tri-n-butyl, n-hexyl phosphonium cation, at least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion, and hydration water. Hereinafter, the tri-n-butyl, n-pentyl phosphonium cation may be abbreviated as "P4445". In addition, the tri-n-butyl, n-hexyl phosphonium cation may be abbreviated as "P4446". P4445 means that three n-butyl groups having 4 carbon atoms and one n-pentyl group having 5 carbon atoms are bonded to one phosphorus (P) center. P4446 means that three n-butyl groups with four carbon atoms and one n-hexyl group with six carbon atoms are bonded to one phosphorus (P) center.

[0039] In addition, SCH preferably comprises at least one cation selected from the group consisting of P4445 and P4446, at least one anion selected from the group consisting of acetate ions, propionate ions, butyrate ions, valerate ions, isovalerate ions, and acrylate ions, and water of hydration. The inclusion of at least one cation selected from the group consisting of P4445 and P4446, and at least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion can be said to mean the inclusion of an ionic substance containing the cation and the anion, or the inclusion of an ionic substance constituted by the cation and the anion.

[0040] In the course of the investigation of the above-mentioned embodiment 1, the inventors conducted single-crystal X-ray crystal structure analysis of a hydrate formed by a hydrate of tri-n-butyl, n-hexylammonium chloride (hereinafter sometimes abbreviated as "N4446Cl") and methane (CH4), and discovered that it had a unique crystal structure. It was found that the hydrate formed by the hydrate of N4446Cl and methane (CH4) has the same framework of the orthorhombic structure known so far, but has a more symmetrical hexagonal structure. Meanwhile, Non-Patent Document 4 discloses powder X-ray diffraction experimental data on variations of the alkyl group R of tri-n-butyl alkylphosphonium bromide (P444RBr). The inventors of the present application found that the crystal structure analysis data of P4445Br, which showed a unique structure, is similar to the experimental data of the hydrate formed by the hydrate of N4446Cl and methane (CH4). This led the present inventors to believe that P4445, among P444R, would form an SCH similar to that of N4446. The present inventors also believed that P4446, as an extension of P4445, would also conform to a similar SCH structure and exhibit similar properties. In this way, by containing at least one cation selected from the group consisting of P4445 and P4446, and also containing water of hydration and an anion described below, SCH is formed regardless of the presence of a halogen element. In other words, it is preferable that SCH does not contain a halogen element. The formation of SCH can be confirmed by X-ray crystal structure analysis.

[0041] The content of at least one cation selected from the group consisting of P4445 and P4446 in SCH is not particularly limited as long as SCH can be formed, and may be, for example, 20 to 40 mass %.

[0042] As for other configurations such as the hydration water and anions contained in SCH, the configurations described in the first embodiment can be adopted for the same reasons.

[0043] <Heat storage material> The heat storage material according to the second embodiment of the present disclosure includes an ionic material and water. The ionic material includes at least one cation selected from the group consisting of tri-n-butyl, n-pentyl phosphonium cation (P4445) and tri-n-butyl, n-hexyl phosphonium cation (P4446), and at least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylic acid ion. The ionic material preferably includes at least one cation selected from the group consisting of P4445 and P4446, and at least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylic acid ion. The heat storage material is also preferably composed of an ionic material and water.

[0044] When the ionic substance contained in the heat storage material contains at least one cation selected from the group consisting of P4445 and P4446 and an anion described below, and the heat storage material contains water, the heat storage material becomes a heat storage material that can form SCH regardless of the presence of a halogen element. That is, it is preferable that the heat storage material does not contain a halogen element. For example, when the temperature of the heat storage material is higher than the melting point, the hydration water contained in the heat storage material dissociates. Thereafter, by lowering the temperature of the heat storage material to the melting point or lower, at least a part of the water contained in the heat storage material becomes hydration water and forms SCH. That is, it can also be said that SCH is a heat storage material.

[0045] The content of at least one cation selected from the group consisting of P4445 and P4446 in the heat storage material is not particularly limited as long as it is capable of forming SCH, and may be, for example, 20 to 40 mass %.

[0046] As for other configurations such as water and anions contained in the heat storage material, the configurations described in the first embodiment can be adopted in a similar manner.

[0047] <Method of manufacturing semi-clathrate hydrate (SCH)> The method for producing SCH according to the second embodiment of the present disclosure can be the same as the method for producing SCH according to the first embodiment of the present disclosure. In the preparation step for the production, a specific phosphonium hydroxide may be used instead of the ammonium hydroxide of the first embodiment. EXAMPLES

[0048] The present invention will be explained in more detail below with reference to examples, but is not limited to these examples as long as the gist of the invention is not exceeded.

[0049] <Example 1> (Synthesis of ammonium salts) Into a sealed glass container (Sansho, vacuum tube), 46g of the raw materials tri-n-butylamine (Tokyo Chemical Industry Co., Ltd.), 49g of hexyl bromide (Tokyo Chemical Industry Co., Ltd.), and 94g of the solvent nitrobenzene (Fujifilm Wako Pure Chemical Industries Co., Ltd.) were added. The molar ratio of tri-n-butylamine to hexyl bromide was 1:1. The remaining air in the sealed glass container was replaced with nitrogen, and then the container was evacuated, and the mixture was heated and reacted in a silicon oil bath while stirring with a magnetic stirrer. The reaction conditions were 80°C and 66 hours.

[0050] After the reaction, heating was stopped and the product was extracted with water. After repeating the extraction three or more times, the resulting aqueous solution was put into an evaporator to remove the water, and tri-n-butyl, n-hexylammonium bromide was obtained. The resulting aqueous solution of tri-n-butyl, n-hexylammonium bromide was passed through an anion exchange resin (Oregano, IRA402BL(OH)-HG) to exchange Br ions for OH ions, and tri-n-butyl, n-hexylammonium hydroxide was obtained. Ion chromatography confirmed that the Br ion concentration after ion exchange was less than 0.1 mass%. 0.013 moles of the obtained tri-n-butyl, n-hexylammonium hydroxide and 0.013 moles of valeric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were neutralized at room temperature for 1 hour. The reaction was quantitative. After removing water from the obtained aqueous solution using an evaporator, the aqueous solution was adjusted to a concentration of approximately 30% by mass. The aqueous solution was cooled in a thermostatic water bath to obtain SCH. The physical properties are shown in Table 1.

[0051] (Melt point measurement) SCH was crystallized at 0.5°C in a thermostatic water bath, and the remaining liquid that did not crystallize was removed. The melting point of the remaining crystals was measured by observing SCH under a microscope while increasing the temperature of the thermostatic water bath. Since the viscosity of the molten liquid is high and it may not be mixed sufficiently if left to stand, the sample aqueous solution and solid placed in a test tube in the thermostatic water bath were stirred with a shaker. The temperature of the thermostatic water bath was increased by 1°C at a time, and the waiting time at each temperature was more than 1 hour. The temperature one step before the temperature at which the solid disappeared in the test tube was taken as the melting point. For example, when the solid disappeared at 2°C, the melting point was taken as the previous set temperature of 1°C. The thermometer used was a platinum resistance thermometer that conformed to the Japan Industrial Association PT100 Class A standard. A microscope with a magnification of 0.5 to 2 times was sufficient for observing the crystals. The crystals melted completely at 6°C.

[0052] (Measurement of hydration number) 90 mg of the melt of the crystals obtained above was measured for moisture content using a volumetric Karl Fischer moisture meter (KF-31, manufactured by Mitsubishi Chemical Corporation), and the hydration number was calculated from the measured moisture content.

[0053] (Latent heat measurement) The latent heat was measured using a differential scanning calorimeter (DSC7020 manufactured by Hitachi High-Technologies Corporation). Measurements using a differential scanning calorimeter are hereinafter referred to as "DSC measurements." 15 mg of the above melted liquid was sealed in a simple sealed aluminum pan. Since ice may form when supercooled below the freezing point, the pan was first cooled to -30°C, then heated to about 3°C, and then cooled again. After repeating this process 2-3 times, the ice melting peak disappeared, and only the SCH melting peak remained. This confirmed that all of the sealed melted liquid had become SCH.

[0054] In DSC measurements, sample filling volume and heat quantity are obtained as data. Sample filling volume is measured by using a mass balance to measure the volume of aqueous solution filled in the measurement container (pan). Heat quantity is output directly from the differential scanning calorimeter. Hmass (kJ / kg) is obtained by dividing the obtained heat Q (J) by the filling volume m (g).

[0055] On the other hand, the latent heat per mole of ion (kJ / mol) is calculated as follows. For example, if ion pair X forms a hydrate with hydration number N, the latent heat is calculated as follows: Here, the latent heat is Hmass (kJ / kg) and the molecular weight of each is M X , M H2O (g / mol). If the unit composition of a hydrate is based on one ion (i.e., one cation and one anion ion pair), the composition is X+N H2O, so the molecular weight of this unit composition is M X +N×M H2O In calorimetry, the amount of heat per unit composition, Hmol (kJ / mol), can be calculated using the latent heat, Hmass (kJ / kg), according to the following formula (1). Hmol = (Hmass / 1000) × (M X +N×M H2O) (1) Hmol is an index of the latent heat obtained from 1 mole of ion in each hydrate. Table 1 below shows the heat per weight, Hmass (kJ / kg), and the heat per unit composition, Hmol (kJ / mol), obtained by the above method.

[0056] <Examples 2 to 6> In Examples 2 to 6, the anion of Example 1 was changed to another carboxylic acid, and SCH was obtained in the same manner as in Example 1, except that the carboxylic acids shown in Table 1 were used. Isovaleric acid in Example 2, propionic acid in Example 3, acrylic acid in Example 5, and acetic acid in Example 6 were all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Only butyric acid in Example 4 was manufactured by Tokyo Chemical Industry Co., Ltd.

[0057] <Comparative Example 1> Comparative Example 1 is tri-n-butyl, n-hexylammonium bromide (N4446Br), which is a bromide of N4446. N4446Br was used as an intermediate product for synthesizing the ionic compounds of Examples 1 to 6 described above. N4446Br did not form a hydrate at 0°C or higher. In other words, the melting point, latent heat, etc. could not be measured.

[0058] <Comparative Example 2> Comparative Example 2 is tetra-n-butylammonium bromide (26 hydrate), which is widely used as a heat storage material. The abbreviation for tetra-n-butylammonium bromide is N4444Br. The physical properties of N4444Br shown in Table 1 are quoted from the values ​​described in Non-Patent Document 5.

[0059] <Comparative Example 3> Comparative Example 3 is tri-n-butyl, n-pentyl ammonium bromide, which is widely used as a heat storage material. The abbreviation for tri-n-butyl, n-pentyl ammonium bromide is N4445Br. The physical properties of N4445Br shown in Table 1 are quoted from the values ​​described in Non-Patent Document 6.

[0060] Table 1 summarizes the physical properties of the ionic substances of Examples 1-6 and Comparative Examples 1-2. [Table 1] N4446: Tri-n-butyl, n-hexyl ammonium cation N4444: Tetra-n-butylammonium cation N4445: Tri-n-butyl, n-pentyl ammonium cation In the table, the latent heat per mole indicates the latent heat per mole of SCH ions.

[0061] In all of the carboxylate anions in Examples 1 to 6, the hydration number exceeds 40. Furthermore, the latent heat per mole in all of Examples 1 to 6 exceeds that of Comparative Example 2. In Examples 1 to 5, the hydration number exceeds 42, and the latent heat per mole is a large value in the range of 229 to 261. In particular, in Examples 1 and 2, which used valeric acid and isovaleric acid, the hydration numbers were extremely high at 48 and 50. It is noteworthy that the melting point is large and the latent heat per mole exceeds 250. It is also noteworthy that the examples using butyric acid and propionic acid in Examples 3 and 4 have a melting point of 5°C. This is because they are suitable for applications such as cooling agents at temperatures higher than the melting point of ice, 0°C. Furthermore, the butyric acid in Example 3 achieves the maximum latent heat per kg of 216. Ammonium salts were used in Examples 1 to 6, but ammonium salts are often less toxic and less corrosive to metals than phosphonium salts, and from this viewpoint, ammonium salts have relatively favorable properties.

[0062] Examples of the invention understood from the above disclosure are as follows. [Configuration 1] A heat storage material comprising an ionic material and water, The ionic substance is At least one cation selected from the group consisting of tri-n-butyl, n-hexyl ammonium cation, tri-n-butyl, n-pentyl phosphonium cation, and tri-n-butyl, n-hexyl phosphonium cation; At least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion; A heat storage material comprising: [Configuration 2] 2. The heat storage material according to claim 1, wherein the cation is a tri-n-butyl, n-hexyl ammonium cation. [Configuration 3] 3. The heat storage material according to aspect 1 or 2, having a melting point of 3.0 to 10.0°C. [Configuration 4] A heat storage agent comprising the heat storage material according to any one of aspects 1 to 3. [Configuration 5] A heat transport medium comprising the heat storage material according to any one of claims 1 to 3. [Configuration 6] At least one cation selected from the group consisting of tri-n-butyl, n-hexyl ammonium cation, tri-n-butyl, n-pentyl phosphonium cation, and tri-n-butyl, n-hexyl phosphonium cation; At least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion; and water of hydration. [Configuration 7] 7. The semiclathrate hydrate of claim 6, wherein the cation is a tri-n-butyl, n-hexyl ammonium cation. [Configuration 8] 8. The semiclathrate hydrate according to claim 6 or 7, wherein the hydration number of the semiclathrate hydrate is 40.0 or more. [Configuration 9] 9. The semiclathrate hydrate according to any one of claims 6 to 8, having a melting point of 3.0 to 10.0°C. [Configuration 10] 10. The semiclathrate hydrate according to any one of claims 6 to 9, wherein the semiclathrate hydrate has a latent heat per mole of ions of 200 kJ / mol or more.

Claims

1. A heat storage material comprising an ionic material and water, The ionic substance is At least one cation selected from the group consisting of tri-n-butyl, n-hexylammonium cation, tri-n-butyl, n-pentylphosphonium cation, and tri-n-butyl, n-hexylphosphonium cation; At least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion; A heat storage material comprising:

2. 2. The heat storage material according to claim 1, wherein the cation is a tri-n-butyl, n-hexyl ammonium cation.

3. The heat storage material according to claim 1 or 2, having a melting point of 3.0 to 10.0°C.

4. A heat storage agent comprising the heat storage material according to claim 1 or 2.

5. A heat transport medium comprising the heat storage material according to claim 1 or 2.

6. At least one cation selected from the group consisting of tri-n-butyl, n-hexylammonium cation, tri-n-butyl, n-pentylphosphonium cation, and tri-n-butyl, n-hexylphosphonium cation; At least one anion selected from the group consisting of acetate ion, propionate ion, butyrate ion, valerate ion, isovalerate ion, and acrylate ion; and water of hydration.

7. 7. The semiclathrate hydrate of claim 6, wherein the cation is a tri-n-butyl, n-hexyl ammonium cation.

8. The semiclathrate hydrate according to claim 6 or 7, wherein the semiclathrate hydrate has a hydration number of 40.0 or more.

9. The semiclathrate hydrate according to claim 6 or 7, having a melting point of 3.0 to 10.0°C.

10. The semiclathrate hydrate according to claim 6 or 7, wherein the semiclathrate hydrate has a latent heat per mole of ions of 200 kJ / mol or more.

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