Composition and heat storage material

Abstract

To provide a composition that is suitable as a component of a heat storage material and exhibits superior performance, and also to provide a heat storage material.SOLUTION: One form of the present invention is a composition for a heat storage material that contains water and ammonium formate.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a composition and a heat storage material. [Background technology]

[0002] Phase change materials are one type of heat storage material that can maintain a certain temperature. Phase change materials are materials that can maintain a constant temperature by utilizing the latent heat generated when they change from a solid phase to a liquid phase.

[0003] Thermal storage materials are sometimes used to keep fresh foods, frozen foods, medical supplies (pharmaceuticals), and the like cool. In particular, for storing some seafood and high-milk fat ice cream, temperatures of -30°C to -40°C must be maintained. Traditionally, dry ice has often been used as a cooling material for such extremely low temperatures. However, in recent years, the demand for a decarbonized society has led to a decrease in the production of CO2 used in dry ice manufacturing and a rise in the price of dry ice, and there is a demand for thermal storage materials that can replace dry ice.

[0004] As a heat storage material made of a phase-change material suitable for such an extremely low temperature range, Patent Document 1 discloses a composition using magnesium chloride. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-007499 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the compositions disclosed in Patent Document 1 do not fully meet the demands when applied to heat storage materials.

[0007] Therefore, an object of the present invention is to provide a composition suitable for forming a heat storage material and having excellent performance, and to provide the heat storage material.

[0008] The present inventors have conducted extensive research and found that the above problems can be solved by using a composition containing a specific component. [Means for solving the problem]

[0009] One aspect of the present invention is a composition for use in a heat storage material, comprising water and ammonium formate.

[0010] The content of the ammonium formate is preferably 5% by mass or more based on the total amount of the composition. The composition preferably has an endothermic peak temperature upon melting of -30°C or lower as measured by a differential scanning calorimeter (DSC).

[0011] Another aspect of the present invention is a heat storage material comprising a container and the composition contained in the container.

[0012] According to the present invention, it is possible to provide a composition suitable for forming a heat storage material and having excellent performance, and the heat storage material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, when an upper limit value and a lower limit value are separately described, it is deemed that a numerical range combining any upper limit value and any lower limit value is substantially disclosed.

[0014] In the following, when a compound is described, its isomers are also described simultaneously.

[0015] In the following, unless otherwise specified, various measurements are carried out at room temperature (25° C.).

[0016] The components, properties / characteristics, applications, etc. of the composition will be specifically described below, but the present invention is not limited thereto.

[0017] <<Ingredients>> Compositions according to the present disclosure preferably include water and ammonium formate. The composition may also contain other ingredients. Each component will be described below.

[0018] <Water> In the composition, water functions as a solvent for ammonium formate, etc.

[0019] The water is not particularly limited, and may be pure water such as distilled water, ion-exchanged water, or RO (reverse osmosis) water, or ultrapure water.

[0020] The content of water in the composition can be adjusted taking into consideration the concentrations of other components, etc. The content of water is, for example, preferably 20.0 mass% or more, 30.0 mass% or more, 40.0 mass% or more, or 50.0 mass% or more based on the total amount of the composition.

[0021] <Ammonium formate> The composition according to the present disclosure contains ammonium formate. While analyzing the heat storage material properties of various compounds, the present inventors have found that, although the detailed mechanism of action is unclear, by further adding ammonium formate to an aqueous composition, the composition has a melting point at an extremely low temperature (for example, around -35°C) and a high latent heat. In addition, when freezing a general latent heat storage material, a low-temperature environment that is 10°C or more lower than the melting point may be prepared in consideration of the supercooling phenomenon. The composition according to the present disclosure is easy to reduce supercooling and is easy to freeze even at a temperature relatively close to the melting point (for example, an environment of about -40°C, which is about 5°C lower than the melting point). In other words, the composition according to the present disclosure is easy to freeze without preparing an extremely low-temperature environment, so energy loss can be reduced.

[0022] The content of ammonium formate is preferably 5.0% by mass or more, 8.0% by mass or more, 10.0% by mass or more, 15.0% by mass or more, 20.0% by mass or more, 25.0% by mass or more, 30.0% by mass or more, or 35.0% by mass or more based on the total amount of the composition. The upper limit of the content of ammonium formate is not particularly limited, but is, for example, 60.0% by mass or less, 55.0% by mass or less, 50.0% by mass or less, 48.0% by mass or less, or 46.0% by mass or less. For example, when the content of ammonium formate is 15.0% by mass or more, the melting point of the obtained composition tends to be a single peak (the period during which a constant temperature is maintained during melting tends to be long), so that the amount of latent heat can be further increased.

[0023] <Other ingredients> The composition may contain known ingredients such as thickeners (gelling agents), gelling assistants, colorants (dyes, pigments), antibacterial agents, viscosity adjusters, supercooling inhibitors (e.g., ice nucleating bacteria, calcium carbonate, sodium sulfate, disodium hydrogen phosphate, borax, activated carbon, silver iodide, minerals, and other crystal nucleating agents), antifoaming agents, and organic solvents other than water.

[0024] When the composition contains a thickener (gelling agent), any conventionally known thickener can be used, such as polysaccharides, gelatin, polyacrylic acid (salt), polyacrylamide, polyvinyl alcohol, etc.

[0025] Examples of polysaccharides include cellulose derivatives such as carboxymethylcellulose (CMC), alginic acid, agar, etc. In addition, alginic acid, carboxymethylcellulose, etc. also include salt forms such as sodium salts.

[0026] The content of the thickener in the composition can be adjusted so that the composition has a predetermined viscosity, and is not particularly limited.The content of the thickener in the composition can be, for example, 0.1 parts by mass or more, 0.5 parts by mass or more, or 1.0 parts by mass or more, and 10.0 parts by mass or less, or 5.0 parts by mass or less, based on the total amount of the composition.

[0027] <<Physical properties / properties>> <Thermal properties> The endothermic peak temperature (melting point) upon melting of the composition of the present disclosure, as measured by differential scanning calorimetry (DSC), is, for example, −25.0° C. or lower, −30.0° C. or lower, −31.0° C. or lower, −32.0° C. or lower, or −33.0° C. or lower.

[0028] The latent heat of the composition of the present disclosure is, for example, 50 J / g or more, 100 J / g or more, 150 J / g or more, or 200 J / g or more, depending on the concentration of ammonium formate, etc.

[0029] The melting point and latent heat of the composition are obtained by a differential scanning calorimeter (DSC). Specifically, the melting point and latent heat are as follows. About 10 mg of the composition is placed in an aluminum pan for DSC measurement, heated to 25°C, cooled to -70°C at a rate of 1°C / min to solidify, and then heated back to 25°C at a rate of 1°C / min. The melting point and latent heat are obtained from the apex and area of ​​the peak that appears during the phase change. When a composition has multiple peaks (melting peaks), the temperature corresponding to the lowest peak position is taken as the melting point of the composition.

[0030] <Viscosity> The viscosity of the composition is not particularly limited and can be appropriately changed depending on the application. When the composition contains a gel component, the viscosity of the composition can be 1.0 Pa s or more, 2.0 Pa s or more, 5.0 Pa s or more, 10 Pa s or more, 100 Pa s or more, or 500 Pa s or more. The upper limit of the viscosity of the composition is not particularly limited, but is, for example, 2000 Pa s or less.

[0031] The viscosity of the composition is measured at 25° C. using a B-type rotational viscometer.

[0032] <<Applications>> The composition according to the present disclosure can be preferably used as a heat storage material. In particular, according to the present disclosure, a composition having an excellent latent heat amount and a melting point at an extremely low temperature (for example, -30.0°C or lower) can be obtained, so that it can be preferably used as a heat storage material for maintaining a low temperature. Therefore, the composition according to the present disclosure can be applied to various heat storage materials. More specifically, the composition according to the present disclosure can be preferably used as a heat storage material (a heat storage material for keeping these items warm during transportation or storage) used in foods (fresh foods, frozen foods) and medical products (vaccines, blood products, red blood cell products, cells, etc.), and is more preferably used as a heat storage material for frozen foods. In addition, the composition according to the present disclosure is useful as a substitute for dry ice, and can be preferably used as a heat storage material for high milk fat ice cream that requires cooling to -30°C or lower.

[0033] <Heat storage material> Hereinafter, as an example of a specific method of using the composition according to the present disclosure, a heat storage material including the composition according to the present disclosure will be described.

[0034] The thermal storage material includes a container and a composition contained within the container.

[0035] The composition is as described above, and therefore a detailed description thereof will be omitted.

[0036] As described above, the composition may be gelled (containing a gel component). By using a gelled composition, leakage of the liquid material when the container is broken can be suppressed.

[0037] The material of the container preferably has a degree of flexibility that allows it to deform in response to the phase changes (solidification and melting) of the composition.

[0038] The heat storage material may be a so-called soft type in which the container is made of a material that is easily deformed, such as a resin film or a metal film, or it may be a so-called hard type in which the container is made of a material that is less likely to deform, such as a thick resin material (e.g., a hollow molded body).

[0039] The heat storage material may be configured so that at least the composition is sealed in a container, and may be configured so that the composition can be removed or poured without destroying the container, for example by having an openable and closable lid, or may be configured so that the composition is difficult to remove without destroying the container.

[0040] The size and shape of the heat storage material can be appropriately changed depending on the application of the heat storage material.

[0041] The heat storage material may include components other than the container and the composition.

[0042] The composition according to the present disclosure may also be used in the form of a food cooling device or a medicine cooling device. The food cooling device and medicine cooling device include, for example, a container and a composition according to the present disclosure contained in the container.

[0043] The composition is as described above, and therefore a detailed description thereof will be omitted.

[0044] The container is, for example, a box-shaped article, and has a space inside the container that can accommodate an object to be kept cold, such as food. A composition storage section containing the composition according to the present disclosure is arranged on at least one or all of the inner side, inner bottom, and inner top surfaces of the container. The composition storage section may be configured to be removable from the container, or may be integrated with the container. The container usually has an opening and closing section, which is operated to be in a sealed state or an open state. The container is preferably made of a material having thermal insulation properties. The object to be kept cold, such as food or medicine, can be kept cold by storing the object to be kept cold in the space inside the container while the composition is solidified.

[0045] Examples of items that can be kept cool using the food cooling equipment include frozen foods, ice cream, produce such as vegetables and fruits, and processed foods such as ham.

[0046] The items to be kept cool using the medicine cooling equipment include some medicines that require low temperature storage, such as blood, specimens, and vaccines. EXAMPLES

[0047] The composition (heat storage material composition) will be specifically described below with reference to examples, but the present invention is not limited to the following.

[0048] <Preparation of Composition> The raw materials shown in Table 1 were mixed in the amounts (parts by mass) shown in Table 1 and stirred to obtain compositions according to Examples 1 to 6 and Comparative Example 1.

[0049] <Measurement / Evaluation> Based on the above-mentioned differential scanning calorimetry, the melting point (endothermic peak temperature upon melting obtained by DSC: DSC peak melting point) and latent heat of each composition were measured. The measurement results of each item are shown in Table 1.

[0050] In addition, 25 g of the composition was placed in a low-temperature bath at -40°C to check the temperature change, and the temperature at the time when heat generation from solidification occurred was measured as the freezing initiation temperature. Furthermore, compositions whose time from the time the composition was placed in the low-temperature bath to the time the freezing onset temperature was measured (the time heat generation from solidification occurred) was within 3 hours were evaluated as having freezing performance A, and those whose time exceeded 3 hours were evaluated as having freezing performance B. The measurement / evaluation results for each item are shown in Table 1.

[0051] [Table 1]

[0052] The compositions according to Examples 1 to 5 had melting points at extremely low temperatures, could be frozen at -40°C, and had much higher latent heat than the composition (magnesium chloride-based composition) of Comparative Example 1. Furthermore, the compositions according to Examples 1 to 5 had melting points with a single peak. The composition of Example 6 had a melting point at an extremely low temperature, was freezable at -40°C, and had a sufficiently high latent heat considering that the amount of solute contained in the composition was very small (small environmental impact or low production cost). From the above, it was demonstrated that the compositions according to Examples 1 to 6 are useful as a cooling storage agent.

Claims

1. A composition for use in heat storage comprising water and ammonium formate.

2. The composition according to claim 1 , wherein the content of the ammonium formate is 5% by mass or more based on the total amount of the composition.

3. 3. The composition according to claim 1, which has an endothermic peak temperature upon melting measured by differential scanning calorimetry (DSC) of −30.0° C. or lower.

4. A heat storage material comprising a container and the composition according to claim 1 or 2 housed in the container.

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