Composition and heat storage material

Abstract

To provide a novel composition for a heat storage material having excellent performance in cold storage around -7°C.SOLUTION: One embodiment of the present invention is a composition for a heat storage material, comprising water, a first component, and a second component. The first component is a dihydrogen phosphate. The second component is a compound having a eutectic point with water of -5°C or more.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] Heat storage materials are sometimes used to keep fresh foods, frozen foods, beverages, medical supplies (pharmaceuticals), etc., cool. In addition, heat storage materials are required to have various temperature ranges depending on the object to be kept cool. For example, when storing cheese, it may be required to maintain a temperature range of -10 to -2°C. Heat storage materials that use latent heat are prone to supercooling when solidifying, so they need to be solidified at a temperature lower than the melting point of the heat storage material. Heat storage materials used in such temperature ranges of -10°C or higher have the advantage of being highly versatile, as they can be used in ordinary households because they are prone to freezing in home freezers (temperature range of about -18°C) even if supercooling occurs.

[0004] As a heat storage material for use in such a temperature range of -10°C or higher, Patent Document 1 discloses a composition that is composed of an alkali metal succinate and water and has a melting point at about -5°C. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-043668 Summary of the Invention [Problem to be solved by the invention]

[0006] However, compositions that are particularly suitable for keeping foods at temperatures around -7°C have not been thoroughly studied.

[0007] Therefore, an object of the present invention is to provide a novel composition for a heat storage material that has excellent performance in keeping things cold at around -7°C. [Means for solving the problem]

[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.

[0009] One aspect of the present invention comprises comprising water, a first component, and a second component, the first component is a dihydrogen phosphate salt; The second component is a compound having a eutectic temperature with water of -5°C or higher. The present invention relates to a composition for a heat storage material.

[0010] It is preferable that the ratio (M1 / M2) of the content of the second component (M2) to the content of the first component (M1) based on the total amount of the composition is 0.4 to 5.0. The content (M1) of the first component is preferably 4.0% by mass or more based on the total amount of the composition.

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

[0012] Yet another aspect of the present invention is The food and drink cooling device comprises a container and the composition contained in the container. Effect of the Invention

[0013] According to the present invention, there is provided a novel composition for a heat storage material having excellent performance in keeping a temperature at about -7°C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 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.

[0015] In the following, when a compound is described, its isomers are also described simultaneously.

[0016] In the following, unless otherwise specified, various measurements are carried out at room temperature (25° C.) and under normal pressure.

[0017] The components, properties / characteristics, applications, etc. of the composition will be specifically described below, but the present invention is not limited thereto.

[0018] <<Ingredients>> The composition according to the present disclosure preferably comprises water, a first component, and a second component. The composition may also contain other ingredients. Each component will be described below.

[0019] <Water> In the composition, water functions as a solvent or a dispersion medium for the first component and the second component.

[0020] 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.

[0021] <First component> The first component is a dihydrogen phosphate salt.

[0022] Examples of the dihydrogen phosphate include sodium dihydrogen phosphate, potassium dihydrogen phosphate, calcium dihydrogen phosphate, ammonium dihydrogen phosphate, etc. The dihydrogen phosphate is preferably ammonium dihydrogen phosphate.

[0023] <Second component> The second component is a compound (particularly an inorganic salt) whose eutectic temperature with water (hereinafter sometimes simply referred to as the eutectic temperature) is -5°C or higher. The eutectic temperature of water and a compound is referred to as a known physical property shown in a phase diagram. The eutectic temperature of water and a compound can also be measured. The eutectic temperature of water and a compound can be measured, for example, by preparing a solution of eutectic concentration of water and the compound and measuring it from the melting peak temperature according to differential scanning calorimetry (DSC) described later. Even if the eutectic concentration of water and the compound is unknown, it is possible to prepare aqueous solutions of different concentrations, measure each solution by DSC, and if a single melting peak is obtained, the eutectic temperature can be measured from the peak temperature.

[0024] The second component preferably has a eutectic temperature with water of -4.5°C or higher, -4.0°C or higher, -3.5°C or higher, or -3.0°C or higher, and preferably -1.0°C or lower, -1.5°C or lower, or -2.0°C or lower.

[0025] From another viewpoint, the difference (|T1-T2|) between the eutectic temperature T1 of water and the first component and the eutectic temperature T2 of water and the second component is preferably 0.5°C or more, or 1.0°C or more, and more preferably 8.0°C or less, 6.0°C or less, or 4.0°C or less.

[0026] Specific examples of the second component include nickel sulfate (eutectic temperature: -4.15°C, eutectic latent heat: 259 J / g), magnesium sulfate (eutectic temperature: -3.9°C, eutectic latent heat: 264 J / g), sodium fluoride (eutectic temperature: -3.5°C, eutectic latent heat: 314 J / g), sodium hydroxide (eutectic temperature: -2.8°C, eutectic latent heat: 266 J / g), potassium nitrate (eutectic temperature: -2.8°C, eutectic latent heat: 296 J / g), sodium carbonate (eutectic temperature: -2.1°C, eutectic latent heat: 310 J / g), iron sulfate (eutectic temperature: -1.8°C, eutectic latent heat: 287 J / g), and copper sulfate (eutectic temperature: -1.6°C, eutectic latent heat: 291 J / g).

[0027] From the viewpoint of improving the stability of performance and safety, the second component preferably contains at least one selected from the group consisting of sulfates, nitrates and carbonates, and more preferably potassium nitrate.

[0028] By making the composition containing water, the first component, and the second component, it becomes easy to obtain a composition that has a melting point around -7°C and has excellent cold storage ability in a temperature range of -10 to -2°C or -10 to -5°C (particularly around -7°C). In addition, since the composition containing the first component and the second component is likely to become a stable and uniform composition, it is easy to obtain a composition having a high latent heat amount and is also excellent in repeated use. In addition, in a composition containing water, the first component, and the second component, since precipitation of the second component is likely to occur when cooled to a low temperature, it is presumed that the second component becomes a crystal nucleating agent, which makes it easy for the entire cold storage material to freeze, and supercooling is easily suppressed. In addition, the composition according to the present disclosure can increase the heat storage amount without using particularly dangerous components such as hazardous substances, and can reduce adverse effects on the environment.

[0029] <Content of each ingredient> The water content of the composition can be adjusted taking into consideration the concentrations of other components, etc. The water content of the composition is, for example, preferably 20.0 mass% or more, 30.0 mass% or more, 40.0 mass% or more, 50.0 mass% or more, 60.0 mass% or more, or 70.0 mass% or more based on the total amount of the composition.

[0030] The content M1 of the first component in the composition is preferably 1.0 mass% or more, 2.0 mass% or more, 3.0 mass% or more, 4.0 mass% or more, 5.0 mass% or more, 8.0 mass% or more, or 10.0 mass% or more, based on the total amount of the composition, and is preferably 30.0 mass% or less, or 25.0 mass% or less.

[0031] The content M2 of the second component in the composition is preferably 1.0 mass% or more, 2.0 mass% or more, 3.0 mass% or more, 4.0 mass% or more, 5.0 mass% or more, 8.0 mass% or more, or 10.0 mass% or more, based on the total amount of the composition, and is preferably 30.0 mass% or less, or 25.0 mass% or less.

[0032] The ratio (M1 / M2) of the content M2 of the second component to the content M1 of the first component is preferably 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more, and is preferably 8.0 or less, 6.0 or less, 5.0 or less, 4.0 or less, 3.0 or less, or 2.0 or less.

[0033] By setting the first component content M1 and the second component content M2 within such preferred ranges, a composition with high cooling ability at around -7°C can be easily obtained.

[0034] <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.

[0035] 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.

[0036] 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.

[0037] The content of the thickener in the composition can be adjusted so that the composition has a predetermined viscosity, and is not particularly limited. For example, when the total amount of water, the first component, and the second component is 100.0 parts by mass, the content of the thickener in the composition is preferably 0.1 parts by mass or more, 0.5 parts by mass or more, or 1.0 parts by mass or more, and is preferably 10.0 parts by mass or less, or 5.0 parts by mass or less.

[0038] From the viewpoint of increasing the latent heat quantity, etc. of the composition, the content of other components excluding the thickener, when the total amount of the composition is 100.0 parts by mass, is preferably 5.0 parts by mass or less, 3.0 parts by mass or less, 1.0 part by mass or less, 0.5 parts by mass or less, or 0.1 parts by mass or less.

[0039] <<Physical properties / properties>> <Thermal properties> The composition of the present disclosure may have a melting point of -10.0°C or more, -9.0°C or more, -8.0°C or more, or -7.0°C or more, and may have a melting point of -1.0°C or less, -1.5°C or less, or -2.0°C or less.

[0040] Furthermore, the composition of the present disclosure may have a latent heat of 100 J / g or more, 150 J / g or more, 200 J / g or more, or 220 J / g or more.

[0041] The melting point and latent heat of the composition are obtained by differential scanning calorimetry (DSC). Specifically, the following is performed. About 10 mg of the composition is placed in an aluminum pan for DSC measurement, heated to 25°C, cooled to -35°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.

[0042] <Viscosity> The viscosity of the composition can be appropriately changed depending on the application, and is not particularly limited. 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.

[0043] The viscosity of the composition is measured at 25° C. using a B-type rotational viscometer.

[0044] <<Applications>> The composition according to the present disclosure is preferably used for a heat storage material, a food and beverage cooling tool, or a medicine cooling tool. In other words, a preferred embodiment of the composition according to the present disclosure is a composition for a heat storage material, a food and beverage cooling tool, or a medicine cooling tool.

[0045] Below, as an example of a specific method of using the composition according to the present disclosure, preferred examples of a heat storage material comprising the composition according to the present disclosure, and a food and beverage cooling device and a medicine cooling device comprising the composition according to the present disclosure will be described.

[0046] <Heat storage material> The thermal storage material includes a container and a composition contained within the container.

[0047] The composition is as described above, and detailed description will be omitted. 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.

[0048] The material of the container may be flexible enough to be deformed in response to the phase changes (solidification and melting) of the composition.

[0049] 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).

[0050] 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.

[0051] The size and shape of the heat storage material can be appropriately changed depending on the application of the heat storage material.

[0052] The heat storage material may include components other than the container and the composition.

[0053] <Food and beverage cooling equipment and medicine cooling equipment> The food and drink cooling device and the medicine cooling device include, for example, a container and a composition according to the present disclosure contained in the container.

[0054] The composition is as described above, and therefore a detailed description thereof will be omitted.

[0055] 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.

[0056] Examples of items to be cooled by the food and beverage cooling device include frozen foods, ice cream, produce such as vegetables and fruits, processed foods such as ham, beverages (water, tea-based beverages, coffee-based beverages, fruit beverages, vegetable beverages, sports drinks, etc.), etc. The composition according to the present disclosure is particularly suitable for cooling at temperatures of -10°C or higher (e.g., -10 to -2°C), and is therefore particularly suitable for cooling cheese, fresh fish, meat, dried fish, pickles, etc.

[0057] 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

[0058] 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.

[0059] <<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 12.

[0060] <<Evaluation>> <Melting point and latent heat> The melting point and latent heat of each composition were measured by the above-mentioned differential scanning calorimetry. The measurement results for each item are shown in Table 1.

[0061] <-7±0.5℃ holding time> 25 g of each composition was frozen by leaving it in a low temperature layer at -20°C for 20 hours, and then left to thaw in a thermostatic chamber at 23°C. The time during which the temperature range of -7.5 to -6.5°C was maintained was evaluated as the -7±0.5°C retention time. The -7±0.5°C retention time is preferably 10 minutes or more, more preferably 20 minutes or more, even more preferably 30 minutes or more, and particularly preferably 45 minutes or more.

[0062] <Reusable> 25 g of each composition was frozen by leaving it in a low temperature layer at -20°C for 20 hours, and then left to thaw in a thermostatic chamber at 23°C for 2 hours. This operation was repeated five times, and the -7±0.5°C retention time (the time the temperature range of -7.5 to -6.5°C was maintained) upon thawing was measured after each operation. Regarding the difference between the -7±0.5°C retention time during the first thawing and the -7°C±0.5°C retention time during the fifth thawing, those that were within 5 minutes were evaluated as A, and those that were longer than 5 minutes were evaluated as B.

[0063] [Table 1]

[0064] From the above results, it can be seen that the compositions of each Example have a sufficiently high latent heat, a melting point in the range of -10 to -2°C, a sufficient retention time at -7±0.5°C, and are excellent in terms of repeated use.

Claims

1. comprising water, a first component, and a second component; the first component is a dihydrogen phosphate salt; The second component is a compound having a eutectic temperature with water of −5° C. or higher. A composition for heat storage material, comprising:

2. The content of the second component (M ２ ) and the content of the first component (M １ ) and the ratio (M １ / M ２ 2. The composition according to claim 1, wherein the β-

3. The content of the first component (M １ 2. The composition according to claim 1, wherein the content of .alpha.-methylcellulose is 4.0% by mass or

4. A heat storage material comprising a container and the composition according to any one of claims 1 to 3 contained in the container.

5. A food and drink cooling device comprising a container and the composition according to any one of claims 1 to 3 contained in the container.

Images