Cold storage material

Abstract

To provide a cold storage material that contains tetrahydrofuran, which is beneficial for suppressing syneresis during use and for increasing gel strength.SOLUTION: A cold storage material of the present disclosure comprises tetrahydrofuran, water, and a thickening gelling agent. The content of tetrahydrofuran relative to the total combined content of tetrahydrofuran and water is 0.16 or more and 0.24 or less on a mass basis. The thickening gelling agent includes the main component consisting solely of locust bean gum and xanthan gum. The mass of the xanthan gum relative to the mass of the locust bean gum is 1 or more and 4 or less. In the total amount of the thickening gelling agent, the proportion of components other than the main component is 20 mass% or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a heat storage material. [Background technology]

[0002] Patent Document 1 discloses a heat storage gel material comprising a heat storage liquid and a shape retainer. The heat storage liquid has a heat storage base dispersed in water and has a predetermined phase transition temperature. The shape retainer has a network structure of organic molecules and is formed of agar-based materials at 0.2% by weight or more relative to the heat storage liquid. Tetrahydrofuran (THF) is given as an example of the heat storage base. Patent Document 1 describes an example (see Example 9, etc.) in which a 30% by weight aqueous solution of THF and agar are used.

[0003] Patent Document 2 discloses a heat storage material having a first gelling material, a second gelling material, and an inorganic or aqueous heat storage material. The second gelling material has a different water retention capacity from the first gelling material and is mixed into the first gelling material. The inorganic or aqueous heat storage material is held by the first gelling material and the second gelling material. The first gelling material uses a synthetic polymer such as a polyacrylamide derivative or crosslinked gelatin. The second gelling material uses a natural polymer such as a polysaccharide, agar, or gelatin, and the polysaccharide uses locust bean gum, xanthan gum, gellan gum, or carrageenan. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 190333 [Patent Document 2] International Publication No. 2014 / 091938 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a cold storage material that contains tetrahydrofuran, yet is advantageous in terms of suppressing the occurrence of syneresis during use and in terms of gel strength. [Means for solving the problem]

[0006] The cold storage material in the present disclosure is Tetrahydrofuran, Water, A thickening gelling agent, a ratio of the content of the tetrahydrofuran to the total content of the tetrahydrofuran and the water is, on a mass basis, 0.16 or more and 0.24 or less; The thickening gelling agent contains main components consisting of locust bean gum and xanthan gum only, The ratio of the mass of the xanthan gum to the mass of the locust bean gum is 1 or more and 4 or less; The content of components other than the main component in the total amount of the thickening gelling agent is 20 mass % or less. Effect of the Invention

[0007] The cold storage material of the present disclosure is likely to have the desired gel strength and elasticity due to the action of the thickening gelling agent, and is therefore advantageous from the viewpoint of suppressing the occurrence of syneresis during use while containing tetrahydrofuran. [Brief description of the drawings]

[0008] [Figure 1] Graph showing characteristics of the cold storage material when cooled in the first embodiment [Diagram 2] A diagram of a cooler box in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (The knowledge and other information that formed the basis of this disclosure) At the time when the inventors came up with the present disclosure, a cold storage material that is liquid at room temperature could contaminate an item if the container of the cold storage material is damaged during storage, safekeeping, and transportation. Therefore, in the industry, in order to prevent the cold storage material from leaking and contaminating an item when the container of the cold storage material is damaged, it was common to add a thickening gelling agent to the cold storage material to thicken the cold storage material or gel the cold storage material. Under such circumstances, the inventors were inspired by the fact that the heat of fusion of clathrate hydrate of tetrahydrofuran is large, and came up with the idea of ​​producing a cold storage material containing tetrahydrofuran, water, and a thickening gelling agent. Then, the inventors discovered that in order to realize the idea, there is a problem that a cold storage material containing tetrahydrofuran, water, and a thickening gelling agent is likely to cause water separation during use, and in order to solve the problem, the subject of the present disclosure was constituted.

[0010] Therefore, the present disclosure provides a cold storage material that contains tetrahydrofuran, yet is advantageous in terms of suppressing water separation during use and gel strength.

[0011] Hereinafter, the embodiments will be described in detail with reference to the drawings. However, more detailed description than necessary may be omitted. For example, detailed description of already well-known matters or duplicate description of substantially the same configuration may be omitted.

[0012] It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0013] (Embodiment 1) Hereinafter, the first embodiment will be described with reference to FIG.

[0014] [1-1. Configuration] The cold storage material in the first embodiment contains tetrahydrofuran (THF), water, and a thickening gelling agent. In this cold storage material, the ratio of the THF content to the total amount of the THF content and the water content is 0.16 to 0.24 by mass. The thickening gelling agent contains a main component consisting of only locust bean gum and xanthan gum. In this specification, the "main component" means the component that is contained most abundantly by mass.

[0015] In the cold storage material, THF and water can form a clathrate hydrate. A clathrate hydrate is a crystal in which guest molecules, which are substances other than water, are arranged in a cage-like structure formed by hydrogen bonds of water molecules. The concentration of guest molecules corresponding to a state in which water molecules and guest molecules are present in an adequate amount to form a clathrate hydrate is called the harmonic concentration. When the guest molecule in the clathrate hydrate is THF, the harmonic concentration is about 19% by mass. In the cold storage material in the first embodiment, the above ratio is 0.16 or more and 0.24 or less, so the content of THF is adjusted to the harmonic concentration or near the harmonic concentration.

[0016] The melting point of the regenerator material can be measured, for example, using a differential scanning calorimeter (DSC) as is well known in the regenerator material art.

[0017] Fig. 1 is a graph showing the characteristics of the cold storage material in the first embodiment when it is cooled, and shows the change in temperature of the cold storage material over time when the cold storage material is heated from a state in which THF and water are previously crystallized as THF hydrate. In Fig. 1, the horizontal axis and the vertical axis respectively show time t and temperature T. In section E shown in Fig. 1, the temperature of the cold storage material is maintained at a temperature equal to or lower than the melting point Tm. For example, while the lid of the cooler box is closed, the temperature inside the cooler box is set to be equal to or lower than the melting point Tm so that the temperature of the cold storage material placed inside the cooler box is maintained at or lower than the melting point Tm.

[0018] Next, the cold storage material is gradually heated. See section F in FIG. 1. For example, when the lid of the cooler box is opened at the end of section E, that is, at the beginning of section F, or when the lid is opened and food is put in, the temperature inside the cooler box gradually increases. As a result, when the temperature of the cold storage material reaches the melting point Tm of the cold storage material, the temperature of the cold storage material is maintained near the melting point Tm of the cold storage material. See section G included in FIG. 1. If there is no cold storage material inside the cooler box, the temperature inside the cooler box continuously rises as shown in section Z included in FIG. 1. On the other hand, if there is a cold storage material inside the cooler box, the temperature inside the cooler box is maintained near the melting point of the cold storage material for a certain period of section G. In this way, cold insulation can be achieved by the cold energy stored in the cold storage material. At the end of section G, the crystals of THF hydrate melt and disappear in the cold storage material. As a result, THF hydrate liquefies in the cold storage material. The longer the time during which the cold storage material can maintain a temperature near the melting point Tm, that is, the longer the section G, the higher the cold storage performance of the cold storage material.

[0019] The temperature of the regenerator material containing liquefied THF and water is then increased to equalize with the ambient temperature, see section H included in FIG.

[0020] The regenerator material can be cooled and reused.

[0021] For example, in order to apply a cold storage material using a clathrate hydrate to a cooler box that may contain fresh produce or food, it is advantageous for the following conditions (I), (II), and (III) to be satisfied. Condition (I) The melting point of the ice pack material is equal to or several degrees lower than the appropriate temperature for the fresh produce or food. Condition (II) The regenerator material has a latent heat of 225 J / g or more. Condition (III) The cooling material is not liquid but gelled.

[0022] If condition (I) is satisfied, when the temperature inside the cooler box rises in response to the environmental temperature, the temperature inside the cooler box can be kept below the appropriate temperature for fresh produce or food for a long period of time.

[0023] When condition (II) is satisfied, the cold storage material has a high latent heat. In this specification, the latent heat refers to the heat of fusion. For example, the latent heat of n-tetradecane having a melting point of 5.9°C is 229 J / g. The latent heat of n-pentadecane having a melting point of 9.9°C is 168 J / g. The latent heat of n-hexadecane having a melting point of 18.2°C is 229 J / g.

[0024] If condition (III) is satisfied, in the unlikely event that the container for the cooling storage material is broken, the risk of the components of the cooling storage material scattering over a wide area and contaminating fresh products or food can be reduced.

[0025] The content of the thickening gelling agent in the cold storage material is not limited to a specific value, and is, for example, 1% to 10% by mass.

[0026] In the cold storage material in the first embodiment, the thickening gelling agent is not limited to a specific embodiment as long as it contains the above-mentioned main component. For example, the ratio of the amount of locust bean gum to the total amount of locust bean gum and xanthan gum is not limited to a specific value. The ratio is, for example, 0.15 to 0.85 by mass. This ratio is preferably 0.2 to 0.8, more preferably 0.2 to 0.7, and even more preferably 0.2 to less than 0.6. The ratio of the content of xanthan gum to the total amount of the thickening gelling agent is not limited to a specific value. For example, the ratio may be 0.6 or more by mass, or may be less than 0.6. The thickening gelling agent may contain a component other than the main component, or may contain only the main component. For example, the thickening gelling agent may contain a predetermined amount of a component other than the main component as long as it has the desired characteristics in terms of suppression of syneresis and gel strength. The content of the component other than the main component in the thickening gelling agent is, for example, 20% by mass or less. The content of components other than the main component in the thickening gelling agent may be 15% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less.

[0027] The cold storage material in the first embodiment may contain only THF, water, and a thickening gelling agent, or may contain components other than THF, water, and a thickening gelling agent. The cold storage material may contain additives such as a supercooling inhibitor, a thickener, and a preservative. On the other hand, the cold storage material desirably does not contain a synthetic polymer produced by crosslinking a polyacrylamide derivative, polyvinyl alcohol, sodium polyacrylate, or sodium polymethacrylate.

[0028] The cold storage material may further contain at least one silver compound selected from the group consisting of silver phosphate, silver carbonate, and silver oxide. Silver phosphate is represented by the chemical formula Ag 3 PO 4 Silver carbonate has the chemical formula Ag 2 CO 3 Silver oxide has the chemical formula AgO.

[0029] When the cold storage material contains the above-mentioned silver compound, the molar ratio of the content of the silver compound to the content of water in the cold storage material is not limited to a specific value. The molar ratio is, for example, 2.64×10 -8 3.75×10 or more -4 The following is the result.

[0030] When the cold storage material contains the above-mentioned silver compound, the ratio of the content of the silver compound to the total content of the THF content, the water content, and the thickening gelling agent content in the cold storage material is not limited to a specific value.The ratio is, for example, 0.00050 or more and 0.020 or less on a mass basis.The ratio may be 0.0010 or more and 0.010 or less on a mass basis.

[0031] The method for producing the cold storage material in the first embodiment is not limited to a specific method. The cold storage material in the first embodiment can be produced, for example, by mixing THF, water, and a thickening gelling agent, and following a process including heating and cooling. This process can be applied to a known process.

[0032] The cold storage material may be provided in a sealed container, if desired, in which case the mixture containing THF, water, and a thickening gelling agent or the cold storage material may be placed in the container and the container may be sealed.

[0033] [1-2. Operation] The operation and function of the cold storage material in the first embodiment will be described.

[0034] When using a cold storage material, cold storage and cooling are repeated. When storing cold, THF hydrate is generated from THF and water. When cooling is released, the THF hydrate melts. Therefore, for example, it is possible to keep the temperature below 10°C using the cold storage material.

[0035] The cold storage material contains a thickening gelling agent and is gelled. Therefore, even if the container of the cold storage material is damaged during transportation of an item kept cool by the cold storage material, the cold storage material is unlikely to scatter over a wide area and contaminate the item being transported. Thus, this cold storage material is advantageous in terms of safety during storage, keeping, and transportation.

[0036] In the cold storage material in the first embodiment, the ratio of the THF content to the total amount of the THF content and the water content is 0.16 or more and 0.24 or less on a mass basis. Therefore, in this cold storage material, the THF content is adjusted to the congruent concentration or near the congruent concentration, and the latent heat of the cold storage material is likely to be large. This is because the heat of fusion of the cold storage material that forms the clathrate hydrate is likely to be the highest when the concentration of the guest molecules is near the congruent concentration.

[0037] [1-3. Effects, etc.] As described above, in the present embodiment, the cold storage material contains THF, water, and a thickening gelling agent. In this cold storage material, the ratio of the THF content to the total amount of the THF content and the water content is 0.16 to 0.24 by mass. The thickening gelling agent contains main components consisting of only locust bean gum and xanthan gum.

[0038] This makes it easier for the cold storage material to have the desired gel strength and elasticity. In a gel with poor elasticity, the gel network shrinks over time, and the gaps in the gel network become smaller. As a result, water stored in the gaps in the gel network is more likely to separate. On the other hand, a gel with the desired elasticity is less likely to cause such water separation. Therefore, the cold storage material is advantageous from the viewpoint of suppressing water separation during use while containing tetrahydrofuran.

[0039] As in the present embodiment, the thickening gelling agent does not need to contain a synthetic polymer produced by crosslinking polyacrylamide derivatives, polyvinyl alcohol, sodium polyacrylate, and sodium polymethacrylate. This makes it easier for the cold storage material to have the desired gel strength and elasticity. Therefore, the cold storage material is more advantageous in terms of suppressing the occurrence of water syneresis during use while containing tetrahydrofuran.

[0040] As in the present embodiment, the ratio of the amount of the locust bean gum to the total amount of the locust bean gum and the xanthan gum may be 0.15 or more and 0.85 or less by mass. This makes it easier for the cold storage material to have the desired gel strength and elasticity. Therefore, the cold storage material is more advantageous in terms of suppressing the occurrence of water syneresis during use while containing tetrahydrofuran.

[0041] As in the present embodiment, the content of the components other than the main component in the thickening gelling agent may be 20% by mass or less. Even in this case, the cold storage material can have the desired gel strength and elasticity. Therefore, the cold storage material is more advantageous from the viewpoint of suppressing the occurrence of syneresis during use while containing tetrahydrofuran.

[0042] As in this embodiment, the cold storage material may further contain at least one silver compound selected from the group consisting of silver phosphate, silver carbonate, and silver oxide. As a result, the oxygen atom (hydrophilic group) in the THF molecule is more likely to be stabilized by a coordinate bond with the silver atom of the silver compound than by a hydrogen bond with a water molecule. Therefore, the ratio of THF molecules that are coordinated is likely to be large. The hydrophilic group of the coordinated THF molecule is coordinated to the silver atom, and the hydrophobic group of the THF molecule is surrounded by water. As a result, the THF molecule is in a state suitable for hydrophobic hydration. The oxygen atom of the silver-oxygen bond of the silver compound plays a role in stabilizing the coordinate bond. As a result, the probability that the THF molecule and the water molecule form a clathrate hydrate through molecular motion in the cold storage material is likely to be high. Therefore, supercooling is likely to be suppressed in the cold storage material. As a result, the temperature at which THF hydrate is generated in the cold storage material is likely to be high, for example, the temperature is 0°C or higher, and clathrate hydrate of THF is likely to be formed without forming ice.

[0043] As in the present embodiment, the silver compound may be silver phosphate. This makes the THF molecules in the cold storage material suitable for hydrophobic hydration, and the probability that the THF molecules and water molecules form clathrate hydrate through molecular motion is likely to be high. Therefore, supercooling is likely to be suppressed in the cold storage material.

[0044] As in the present embodiment, the silver compound may be silver carbonate. This makes the THF molecules in the cold storage material suitable for hydrophobic hydration, and the probability that the THF molecules and water molecules form clathrate hydrate through molecular motion is likely to be high. Therefore, supercooling is likely to be suppressed in the cold storage material.

[0045] As in the present embodiment, the silver compound may be silver oxide. This makes the THF molecule in the cold storage material suitable for hydrophobic hydration, and the probability that the THF molecule and the water molecule form clathrate hydrate through molecular motion is likely to be high. Therefore, the supercooling in the cold storage material is likely to be suppressed.

[0046] In the present embodiment, the molar ratio of the silver compound content to the water content in the cold storage material is 2.64×10 -8 3.75×10 or more -4 As a result, the THF molecules in the cold storage material are in a state suitable for hydrophobic hydration, and the probability that the THF molecules and the water molecules form a clathrate hydrate through molecular motion is likely to be high. Therefore, supercooling in the cold storage material is likely to be suppressed.

[0047] As in this embodiment, in the cold storage material, the ratio of the silver compound content to the total amount of the tetrahydrofuran content, the water content, and the thickening gelling agent content may be 0.00050 or more and 0.020 or less on a mass basis. This ratio may be 0.0010 or more and 0.010 or less on a mass basis. As a result, in the cold storage material, the THF molecules are in a state suitable for hydrophobic hydration, and the probability that the THF molecules and water molecules form clathrate hydrate through molecular motion is likely to be high. Therefore, supercooling is likely to be suppressed in the cold storage material.

[0048] (Embodiment 2) The second embodiment will now be described.

[0049] [2-1. Configuration] The cold storage material in the second embodiment contains THF, water, and a thickening gelling agent. The thickening gelling agent contains polysaccharides derived from seeds and polysaccharides derived from microorganisms. The thickening gelling agent can be gelled by heating and cooling. For example, the thickening gelling agent can gel a mixture containing THF, water, and the thickening gelling agent only by adjusting the temperature without adding a cation. The cold storage material is determined to be solid by the solid-liquid determination test of ASTM D 4359-90.

[0050] The seed-derived polysaccharide contained in the thickening gelling agent is not limited to a specific polysaccharide. An example of the seed-derived polysaccharide is locust bean gum.

[0051] The microbial polysaccharide contained in the thickening gelling agent is not limited to a specific polysaccharide. An example of the microbial polysaccharide is xanthan gum.

[0052] In the cold storage material in the second embodiment, the thickening gelling agent is not limited to a specific embodiment as long as it contains polysaccharides derived from seeds and polysaccharides derived from microorganisms. The thickening gelling agent may contain multiple types of polysaccharides. For example, in the cold storage material in the second embodiment, the thickening gelling agent may contain locust bean gum and xanthan gum. In this case, the ratio of the content of xanthan gum to the total amount of the thickening gelling agent is not limited to a specific value. For example, the ratio may be 0.6 or more on a mass basis, or the ratio may be less than 0.6. In addition, for example, the ratio of the amount of locust bean gum to the total amount of locust bean gum and xanthan gum is, for example, 0.15 or more and 0.7 or less on a mass basis. This ratio may be 0.2 or more and 0.7 or less on a mass basis, or may be 0.3 or more and 0.7 or less.

[0053] In the cold storage material of the second embodiment, the ratio of the content of THF to the total content of THF and water is not limited to a specific value, and is, for example, 0.16 to 0.24 on a mass basis.

[0054] The cold storage material in the second embodiment may contain only THF, water, and a thickening gelling agent, or may contain components other than THF, water, and a thickening gelling agent. The cold storage material may contain additives such as a supercooling inhibitor, a thickener, and a preservative. On the other hand, the cold storage material desirably does not contain a synthetic polymer produced by crosslinking a polyacrylamide derivative, polyvinyl alcohol, sodium polyacrylate, or sodium polymethacrylate.

[0055] The cold storage material may further contain at least one silver compound selected from the group consisting of silver phosphate, silver carbonate, and silver oxide. Silver phosphate is represented by the chemical formula Ag 3 PO 4 Silver carbonate has the chemical formula Ag 2 CO3 Silver oxide has the chemical formula AgO.

[0056] When the cold storage material contains the above-mentioned silver compound, the molar ratio of the content of the silver compound to the content of water in the cold storage material is not limited to a specific value. The molar ratio is, for example, 2.64×10 -8 3.75×10 or more -4 The following is the result.

[0057] When the cold storage material contains the above-mentioned silver compound, the ratio of the content of the silver compound to the total content of the THF content, the water content, and the thickening gelling agent content in the cold storage material is not limited to a specific value.The ratio is, for example, 0.00050 or more and 0.020 or less on a mass basis.The ratio may be 0.0010 or more and 0.010 or less on a mass basis.

[0058] The method for producing the cold accumulating material in the second embodiment is not limited to a specific method, and the cold accumulating material in the second embodiment can be produced by referring to the method for producing the cold accumulating material in the first embodiment.

[0059] [2-2. Operation] The operation and function of the cold storage material in the second embodiment will be described.

[0060] When using the cold storage material, cold storage (the production of THF hydrate) and cooling (melting of THF hydrate) are repeated. Therefore, for example, this cold storage material can be used to keep the temperature below 10°C.

[0061] The cold storage material contains a thickening gelling agent and is gelled. In addition, the cold storage material is determined to be solid by the solid-liquid determination test of ASTM D 4359-90. Therefore, for example, even if the container of the cold storage material is broken during transportation of an item being cooled by the cold storage material, there is a low possibility that the cold storage material will scatter over a wide area and contaminate the item being transported. This cold storage material is advantageous from the viewpoint of safety in storage, keeping, and transportation.

[0062] [2-3. Effects, etc.] As described above, in the present embodiment, the cold storage material contains THF, water, and a thickening gelling agent. The thickening gelling agent contains seed-derived polysaccharides and microbial-derived polysaccharides. The cold storage material is determined to be solid by the solid-liquid determination test of ASTM D 4359-90.

[0063] This makes it easy for the cold storage material to have the desired gel strength and elasticity. Therefore, the cold storage material is advantageous from the viewpoint of suppressing the occurrence of water separation during use while containing THF. In addition, the thickening gelling agent can be gelled, for example, by heating and cooling, and can be gelled only by temperature adjustment without adding cations. Therefore, it is possible to avoid the freezing point drop associated with the addition of cations, and the melting point of the THF hydrate in the cold storage material is unlikely to be lowered. In addition, the latent heat of the cold storage material is likely to be large. For example, the latent heat of the cold storage material is likely to be 225 J / g or more.

[0064] As in this embodiment, the thickening gelling agent may contain locust bean gum and xanthan gum. In addition, the ratio of the content of xanthan gum to the total amount of the thickening gelling agent may be 0.6 or more by mass. Furthermore, the ratio of the amount of locust bean gum to the total amount of locust bean gum and xanthan gum may be 0.15 or more and 0.7 or less by mass. This makes it easier for the cold storage material to have the desired gel strength and elasticity. Therefore, the cold storage material is more advantageous from the viewpoint of suppressing the occurrence of syneresis during use while containing THF.

[0065] As in this embodiment, the cold storage material may further contain at least one silver compound selected from the group consisting of silver phosphate, silver carbonate, and silver oxide. This makes the THF molecules suitable for hydrophobic hydration, and the probability that the THF molecules and water molecules form clathrate hydrate in the cold storage material through molecular motion is likely to be high. Therefore, supercooling is likely to be suppressed in the cold storage material. As a result, the temperature at which THF hydrate is generated in the cold storage material is likely to be high, for example, the temperature is likely to be 0°C or higher.

[0066] As in the present embodiment, the silver compound may be silver phosphate. This makes the THF molecules in the cold storage material suitable for hydrophobic hydration, and the probability that the THF molecules and water molecules form clathrate hydrate through molecular motion is likely to be high. Therefore, supercooling is likely to be suppressed in the cold storage material.

[0067] As in the present embodiment, the silver compound may be silver carbonate. This makes the THF molecules in the cold storage material suitable for hydrophobic hydration, and the probability that the THF molecules and water molecules form clathrate hydrate through molecular motion is likely to be high. Therefore, supercooling is likely to be suppressed in the cold storage material.

[0068] As in the present embodiment, the silver compound may be silver oxide. This makes the THF molecule in the cold storage material suitable for hydrophobic hydration, and the probability that the THF molecule and the water molecule form clathrate hydrate through molecular motion is likely to be high. Therefore, the supercooling in the cold storage material is likely to be suppressed.

[0069] In the present embodiment, the molar ratio of the silver compound content to the water content in the cold storage material is 2.64×10 -8 3.75×10 or more -4 As a result, the THF molecules in the cold storage material are in a state suitable for hydrophobic hydration, and the probability that the THF molecules and the water molecules form a clathrate hydrate through molecular motion is likely to be high. Therefore, supercooling in the cold storage material is likely to be suppressed.

[0070] As in this embodiment, in the cold storage material, the ratio of the silver compound content to the total amount of the THF content, the water content, and the thickening gelling agent content may be 0.00050 or more and 0.020 or less on a mass basis. This ratio may be 0.0010 or more and 0.010 or less on a mass basis. As a result, in the cold storage material, the THF molecules are in a state suitable for hydrophobic hydration, and the probability that the THF molecules and the water molecules form a clathrate hydrate through molecular motion is likely to be high. Therefore, supercooling is likely to be suppressed in the cold storage material.

[0071] (Embodiment 3) Hereinafter, the third embodiment will be described with reference to FIG.

[0072] FIG. 2 shows a cooler box 100 according to the third embodiment.

[0073] Cooler box 100 comprises an insulated box 101 having a bottom (not shown) and sides, and an insulated lid 102 .

[0074] For example, the cold storage material in the first or second embodiment is arranged along at least one selected from the group consisting of the inside bottom surface of the insulating box 101, the inside side surface of the insulating box 101, and the inside surface of the insulating lid 102. In Fig. 2, cold storage material packs 110 containing the cold storage material in the first or second embodiment are provided so as to contact each of the four inside side surfaces of the insulating box 101 having a rectangular parallelepiped shape.

[0075] The cold storage material in the first or second embodiment may be disposed in at least one selected from the group consisting of inside the bottom of the insulated box 101, inside the side of the insulated box 101, and inside the insulated lid 102. The cold storage material in the first or second embodiment may be disposed in the internal space of the cooler box 100 in a state where it is contained in a cold storage material pack 110. The internal space of the cooler box 100 is a space formed by, for example, the inner bottom surface of the insulated box 101, the inner side surface of the insulated box 101, and the inner surface of the insulated lid 102.

[0076] The cold storage material in the first or second embodiment may be provided inside at least one selected from the group consisting of the side of the heat-insulating box, the heat-insulating lid of the heat-insulating box, and the heat-insulating box itself. In this case, the cold storage material in the first or second embodiment may be disposed in a state of being enclosed in the cold storage material pack 110.

[0077] At least one selected from the group consisting of medicines, biological tissues, cells, food, and flowers is placed inside the heat-insulating box 101. The cold storage material in the first or second embodiment is used for storing, preserving, or transporting objects that require freshness to be maintained, such as medicines, biological tissues, cells, food, and flowers. For example, medicine 120 is placed inside the heat-insulating box 101 shown in FIG. 2. An example of the medicine is a liquid medicine. An example of the liquid medicine is a vaccine. The cooler box in the third embodiment is provided with the cold storage material in the first or second embodiment, and is therefore suitable for storing, preserving, or transporting objects that require freshness to be maintained. EXAMPLES

[0078] The present disclosure will now be described in more detail with reference to the following examples.

[0079] In the present examples, tetrahydrofuran is abbreviated as “THF.” THF was purchased from Tokyo Chemical Industry Co., Ltd.

[0080] (Example 1A-1) As shown in Table 1, 0.38 g of polysaccharide, 1.83 g of THF, and 7.78 g of pure water were added to a screw tube having a capacity of 60 milliliters to obtain a mixture. The polysaccharide contained only locust bean gum and xanthan gum, and the ratio of the amount of locust bean gum to the total amount of locust bean gum and xanthan gum was 0.5 by mass. The mixture was thoroughly stirred in the screw tube, heated to 60°C, and then allowed to cool naturally. In this manner, the cold storage material according to Example 1A-1 was obtained. In Example 1A-1, the mixture gelled by heating and cooling alone. The screw tube was a glass tube with a screw cap. The content of polysaccharide in the cold storage material was 4% by mass.

[0081] (Melt point and latent heat measurement) Using a differential scanning calorimeter DSC-8500 manufactured by PerkinElmer Japan, differential scanning calorimetry (DSC) was performed on approximately 10 milligrams of the cold storage material according to Example 1A-1. The temperature was adjusted as programmed in advance and the measurement was performed. First, the temperature of the reference material was maintained at 20 degrees Celsius for 10 minutes. Next, the temperature of the reference material was lowered at a rate of 1 degree Celsius per minute. During the cooling process, a temperature rise associated with the generation of THF hydrate in the cold storage material was observed as an exothermic peak, and then the temperature of the cold storage material converged to the programmed temperature. This confirmed that the crystallization of THF hydrate was completed. The temperature of the cold storage material at the start of the temperature rise of the cold storage material during this cooling process was determined to be the crystallization temperature Tc of the cold storage material. After the temperature of the reference material reached minus 20 degrees Celsius, the temperature of the reference material was maintained at minus 20 degrees Celsius for 10 minutes. After that, the temperature of the reference material was raised from minus 20 degrees Celsius to 20 degrees Celsius at a rate of 1 degree Celsius / minute. When the melting of the THF hydrate started, the heat corresponding to the latent heat was absorbed, so the temperature change of the cold storage material stagnated. When the melting of the THF hydrate was completed, the temperature change of the cold storage material converged to the original temperature rise curve. The temperature of the endothermic peak in this case was determined as the melting point Tm, and the endothermic heat was determined as the latent heat. In this way, the melting point Tm and latent heat of the cold storage material according to Example 1A-1 were determined using a differential scanning calorimeter DSC-8500. As a result, the melting point Tm of the cold storage material according to Example 1A-1 was 5.0 degrees Celsius, and the latent heat of the cold storage material was 240 J / g. The results are shown in Table 5.

[0082] (Gel strength test) The cold storage material according to Example 1A-1 was left in an environment of 40°C for 4 hours or more. After that, the screw tube containing the cold storage material according to Example 1A-1 was laid down (tilted 90°) in an environment of 40°C for 3 minutes, and the state of the cold storage material was visually confirmed. Based on the confirmation result, the gel strength of the cold storage material was evaluated according to the following criteria. The results are shown in Table 5. A: No deformation is observed at the interface between the regenerator material and the air, and it extends vertically. B: Relatively small deformation is observed at the interface between the regenerator material and the air. C: Relatively large deformation is observed at the interface between the regenerator material and the air.

[0083] (Evaluation of syneresis) The cold storage material according to Example 1A-1 was left in an environment of 40°C for 4 hours. After that, the screw tube containing the cold storage material was laid down (tilted 90°) in an environment of 40°C for 3 minutes, and the state of the cold storage material was visually confirmed. Based on the confirmation result, the water separation in the cold storage material was evaluated according to the following criteria. The results are shown in Table 5. A: No clear separation of the liquid components is observed. NG: Separation of liquid components is clearly observed.

[0084] (Example 1A-2) A cold storage material according to Example 1A-2 was prepared in the same manner as in Example 1A-1, except for the following points. Polysaccharide, THF, pure water, and silver oxide (II) were added in the amounts shown in Table 1. Silver oxide (II) was silver oxide (II) obtained from Fujifilm Wako Pure Chemical Industries, Ltd., and was added as a supercooling inhibitor. The cold storage material according to Example 1A-2 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0085] (Example 1A-3) A cold storage material according to Example 1A-3 was prepared in the same manner as in Example 1A-1, except for the following points. Polysaccharide, THF, pure water, and silver phosphate (I) were added in the amounts shown in Table 1. Silver phosphate (I) was silver phosphate (I) obtained from Mitsuwa Chemical Co., Ltd., and was added as a supercooling inhibitor. The cold storage material according to Example 1A-3 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0086] (Example 1A-4) A cold storage material according to Example 1A-4 was prepared in the same manner as in Example 1A-1, except for the following points. Polysaccharide, THF, pure water, and silver carbonate were added in the amounts shown in Table 1. The silver carbonate was silver carbonate obtained from Fujifilm Wako Pure Chemical Industries, Ltd., and was added as a supercooling inhibitor. The cold storage material according to Example 1A-4 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0087] (Example 1B-1) A cold storage material according to Example 1B-1 was prepared in the same manner as in Example 1A-1, except for the following points. Polysaccharide, THF, and pure water were added in the amounts shown in Table 1. The cold storage material according to Example 1B-1 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0088] (Example 1B-2) A cold storage material according to Example 1B-2 was prepared in the same manner as in Example 1A-2, except for the following points. Polysaccharide, THF, pure water, and silver oxide (II) were added in the amounts shown in Table 1. The cold storage material according to Example 1B-2 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0089] (Example 1B-3) A cold accumulating material according to Example 1B-3 was prepared in the same manner as in Example 1A-3, except for the following points. Polysaccharide, THF, pure water, and silver phosphate (I) were added in the amounts shown in Table 1. The cold accumulating material according to Example 1B-3 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0090] (Example 1B-4) A cold storage material according to Example 1B-4 was prepared in the same manner as in Example 1A-4, except for the following points. Polysaccharide, THF, pure water, and silver carbonate were added in the amounts shown in Table 1. The cold storage material according to Example 1B-4 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0091] (Example 2A-1) A cold storage material according to Example 2A-1 was prepared in the same manner as in Example 1A-1, except for the following points. Polysaccharides, THF, and pure water were added in the amounts shown in Table 2. The polysaccharides contained only locust bean gum and xanthan gum, and the ratio of the amount of locust bean gum to the total amount of locust bean gum and xanthan gum was 0.4 by mass. The cold storage material according to Example 2A-1 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0092] (Example 2A-2) A cold storage material according to Example 2A-2 was prepared in the same manner as in Example 2A-1, except for the following points. Polysaccharide, THF, pure water, and silver oxide (II) were added in the amounts shown in Table 2. The cold storage material according to Example 2A-2 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0093] (Example 2A-3) A cold storage material according to Example 2A-3 was prepared in the same manner as in Example 2A-1, except for the following points. Polysaccharide, THF, pure water, and silver phosphate (I) were added in the amounts shown in Table 2. The cold storage material according to Example 2A-3 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0094] (Example 2A-4) A cold storage material according to Example 2A-4 was prepared in the same manner as in Example 2A-1, except for the following points. Polysaccharide, THF, pure water, and silver carbonate were added in the amounts shown in Table 2. The cold storage material according to Example 2A-4 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0095] (Example 2B-1) The cold storage material of Example 2B-1 was prepared in the same manner as Example 2A-1 except for the following points. Polysaccharide, THF, and pure water were added in the amounts shown in Table 2. The cold storage material of Example 2B-1 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0096] (Example 2B-2) The cold storage material of Example 2B-2 was prepared in the same manner as Example 2A-2 except for the following points. Polysaccharide, THF, pure water, and silver oxide (II) were added in the amounts shown in Table 2. The cold storage material of Example 2B-2 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0097] (Example 2B-3) The cold accumulating material of Example 2B-3 was prepared in the same manner as Example 2A-3 except for the following points. Polysaccharide, THF, pure water, and silver phosphate (I) were added in the amounts shown in Table 2. The cold accumulating material of Example 2B-3 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0098] (Example 2B-4) The cold storage material of Example 2B-4 was prepared in the same manner as Example 2A-4 except for the following points. Polysaccharide, THF, pure water, and silver carbonate were added in the amounts shown in Table 2. The cold storage material of Example 2B-4 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0099] (Example 2C-1) A cold storage material according to Example 2C-1 was prepared in the same manner as in Example 1A-1, except for the following points. Polysaccharides, THF, and pure water were added in the amounts shown in Table 2. The polysaccharides contained only locust bean gum and xanthan gum, and the ratio of the amount of locust bean gum to the total amount of locust bean gum and xanthan gum was 0.25 by mass. The cold storage material according to Example 2C-1 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0100] (Example 2C-2) The cold storage material of Example 2C-2 was prepared in the same manner as Example 1A-2 except for the following points. Polysaccharide, THF, pure water, and silver oxide (II) were added in the amounts shown in Table 2. The cold storage material of Example 2C-2 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0101] (Example 2C-3) The cold accumulating material of Example 2C-3 was prepared in the same manner as Example 1A-3 except for the following points. Polysaccharide, THF, pure water, and silver phosphate (I) were added in the amounts shown in Table 2. The cold accumulating material of Example 2C-3 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0102] (Example 2C-4) The cold accumulating material of Example 2C-4 was prepared in the same manner as Example 1A-4 except for the following points. Polysaccharide, THF, pure water, and silver carbonate were added in the amounts shown in Table 2. The cold accumulating material of Example 2C-4 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0103] (Example 2D-1) The cold storage material of Example 2D-1 was prepared in the same manner as Example 2C-1 except for the following points. Polysaccharide, THF, and pure water were added in the amounts shown in Table 2. The cold storage material of Example 2D-1 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0104] (Example 2D-2) The cold storage material of Example 2D-2 was prepared in the same manner as Example 2C-2 except for the following points. Polysaccharide, THF, pure water, and silver oxide (II) were added in the amounts shown in Table 2. The cold storage material of Example 2D-2 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0105] (Example 2D-3) The cold accumulating material of Example 2D-3 was prepared in the same manner as Example 2C-3 except for the following points. Polysaccharide, THF, pure water, and silver phosphate (I) were added in the amounts shown in Table 2. The cold accumulating material of Example 2D-3 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0106] (Example 2D-4) The cold accumulating material of Example 2D-4 was prepared in the same manner as Example 2C-4 except for the following points. Polysaccharide, THF, pure water, and silver carbonate were added in the amounts shown in Table 2. The cold accumulating material of Example 2D-4 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0107] (Example 2E-1) A cold storage material according to Example 2E-1 was prepared in the same manner as in Example 1A-1, except for the following points. Polysaccharides, THF, and pure water were added in the amounts shown in Table 3. The polysaccharides contained only locust bean gum and xanthan gum, and the ratio of the amount of locust bean gum to the total amount of locust bean gum and xanthan gum was 0.2 by mass. The cold storage material according to Example 2E-1 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0108] (Example 2E-2) A cold storage material according to Example 2E-2 was prepared in the same manner as in Example 1A-2, except for the following points. Polysaccharide, THF, pure water, and silver oxide (II) were added in the amounts shown in Table 3. The cold storage material according to Example 2E-2 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 5.

[0109] (Example 2E-3) The cold accumulating material of Example 2E-3 was prepared in the same manner as Example 1A-3 except for the following points. Polysaccharide, THF, pure water, and silver phosphate (I) were added in the amounts shown in Table 3. The cold accumulating material of Example 2E-3 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0110] (Example 2E-4) The cold accumulating material of Example 2E-4 was prepared in the same manner as Example 1A-4 except for the following points. Polysaccharide, THF, pure water, and silver carbonate were added in the amounts shown in Table 3. The cold accumulating material of Example 2E-4 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0111] (Example 2F-1) The cold storage material of Example 2F-1 was prepared in the same manner as Example 2E-1 except for the following points. Polysaccharide, THF, and pure water were added in the amounts shown in Table 3. The cold storage material of Example 2F-1 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0112] (Example 2F-2) The cold storage material of Example 2F-2 was prepared in the same manner as Example 2E-2 except for the following points. Polysaccharide, THF, pure water, and silver oxide (II) were added in the amounts shown in Table 3. The cold storage material of Example 2F-2 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0113] (Example 2F-3) The cold accumulating material of Example 2F-3 was prepared in the same manner as Example 2E-3 except for the following points. Polysaccharide, THF, pure water, and silver phosphate (I) were added in the amounts shown in Table 3. The cold accumulating material of Example 2F-3 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0114] (Example 2F-4) The cold accumulating material of Example 2F-4 was prepared in the same manner as Example 2E-4 except for the following points. Polysaccharide, THF, pure water, and silver carbonate were added in the amounts shown in Table 3. The cold accumulating material of Example 2F-4 was evaluated in the same manner as Example 1A-1. The results are shown in Table 5.

[0115] Comparative Example 1 A cold storage material according to Comparative Example 1 was prepared in the same manner as in Example 1A-1, except for the following points. Guar gum was used as the polysaccharide. Guar gum, THF, and pure water were added in the amounts shown in Table 4. In Comparative Example 1, a mixture of guar gum, THF, and pure water was heated to 60°C and then allowed to cool naturally. In Comparative Example 1, gelation was not possible by heating and cooling alone. The cold storage material according to Comparative Example 1 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 6.

[0116] Comparative Example 2 A cold storage material according to Comparative Example 2 was prepared in the same manner as in Example 1A-1, except for the following points. Low-Acyl (LA) gellan gum was used as the polysaccharide. LA gellan gum is also called deacylated gellan gum. LA gellan gum, THF, and pure water were added in the amounts shown in Table 4. In Comparative Example 2, a mixture of LA gellan gum, THF, and pure water was heated to 40°C and then allowed to cool naturally. In Comparative Example 2, gelation was not possible by heating and cooling alone, and calcium lactate (calcium ion) had to be added. The cold storage material according to Comparative Example 2 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 6.

[0117] Comparative Example 3 A cold storage material according to Comparative Example 3 was prepared in the same manner as in Example 1A-1, except for the following points. Agar was used as the polysaccharide. Agar and pure water were added in the amounts shown in Table 4. In Comparative Example 3, a mixture of agar and pure water was heated to 90°C and then allowed to cool naturally. Then, THF was added in the amount shown in Table 4, and the mixture was further stirred and allowed to stand. The cold storage material according to Comparative Example 3 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 6.

[0118] Comparative Example 4 A cold storage material according to Comparative Example 4 was prepared in the same manner as Comparative Example 3, except for the following points. Instead of agar, a mixture of guar gum and agar was used. The agar content in this mixture was 50% by mass. The mixture of guar gum and agar and pure water were added in the amounts shown in Table 4. In Comparative Example 4, the mixture of guar gum, agar, and pure water was heated to 90°C and then allowed to cool naturally. Then, THF was added in the amount shown in Table 4, and the mixture was further stirred and left to stand. The cold storage material according to Comparative Example 4 was evaluated in the same manner as Example 1A-1. The results are shown in Table 6.

[0119] Comparative Example 5 A cold storage material according to Comparative Example 5 was prepared in the same manner as Comparative Example 3, except for the following points. Instead of agar, a mixture of guar gum and agar was used. The agar content in this mixture was 80% by mass. The mixture of guar gum and agar and pure water were added in the amounts shown in Table 4. In Comparative Example 5, the mixture of guar gum, agar, and pure water was heated to 90°C and then allowed to cool naturally. Then, THF was added in the amount shown in Table 4, and the mixture was further stirred and left to stand. The cold storage material according to Comparative Example 5 was evaluated in the same manner as Example 1A-1. The results are shown in Table 6.

[0120] Comparative Example 6 A cold storage material according to Comparative Example 6 was prepared in the same manner as in Example 1A-1, except for the following points. In addition to polysaccharides, THF, and pure water, sodium polyacrylate was added in the amounts shown in Table 4. The sodium polyacrylate was sodium polyacrylate (Poly(acrylic acid), sodium salt, 20% soln. in water [MW 225,000] manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. The cold storage material according to Comparative Example 6 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 6.

[0121] Comparative Example 7 A cold storage material according to Comparative Example 7 was prepared in the same manner as in Example 1A-1, except for the following points. In addition to polysaccharides, THF, and pure water, sodium polyacrylate was added in the amounts shown in Table 4. The cold storage material according to Comparative Example 7 was evaluated in the same manner as in Example 1A-1. The results are shown in Table 6.

[0122] [Table 1]

[0123] [Table 2]

[0124] [Table 3]

[0125] [Table 4]

[0126] [Table 5]

[0127] [Table 6]

[0128] As shown in Table 5, the gel strength of the cold storage material according to each Example was good. In addition, water syneresis was not clearly confirmed in the cold storage material according to each Example, and it was shown that the cold storage material according to each Example is unlikely to syneresis during use, even though it contains THF. In addition, 1L (liter) of cold storage material sample was prepared so that the mass ratio of each component in the cold storage material according to each Example was equal, and the solid-liquid judgment test of ASTM D 4359-90 was performed. As a result, the cold storage material according to each Example was judged to be solid.

[0129] On the other hand, the gel strength of the cold storage materials according to each comparative example was not good. In addition, water syneresis was clearly confirmed in the cold storage materials according to each comparative example, and it was shown that the cold storage materials according to each comparative example are prone to water syneresis during use. It is presumed that the combination of THF and polysaccharide in the cold storage materials according to each comparative example has poor gel elasticity. In Comparative Examples 1 and 2, gelation was not possible by heating and cooling alone, and in Comparative Example 2, the addition of cations, etc. was necessary. There is a concern that the addition of such cations will cause a drop in the freezing point. In Comparative Examples 3 to 5, the mixture of polysaccharide and pure water needs to be heated to 90°C for gelation. This heating temperature is higher than the boiling point of THF, and if such heating is performed in the presence of THF, THF may boil and the properties of the cold storage material may deteriorate. Comparison between Example 1B-1 and Comparative Examples 6 and 7 suggests that the addition of sodium polyacrylate is undesirable from the viewpoint of water syneresis and gel strength. Comparing Comparative Example 6 with Comparative Example 7, it was suggested that the greater the content of sodium polyacrylate, the greater the amount of water syneresis and the lower the gel strength.

[0130] As shown in Table 5, by comparing Example 1A-1 with Examples 1A-2 to 1A-4, it can be understood that the crystallization temperature Tc of the cold storage material is likely to be high when a specific silver compound is added as a supercooling inhibitor. For example, the crystallization temperature of the cold storage material is improved from a low temperature of minus 20 degrees Celsius to a high temperature of 0 degrees Celsius or higher and 3 degrees Celsius or lower. [Industrial Applicability]

[0131] The cold storage material according to the present disclosure can be used for storing, preserving, or transporting objects that require freshness to be maintained, such as medicines, biological tissues, cells, food, and flowers.

Claims

1. Tetrahydrofuran, Water, A thickening gelling agent, a ratio of the content of the tetrahydrofuran to the total content of the tetrahydrofuran and the water is, on a mass basis, 0.16 or more and 0.24 or less; The thickening gelling agent contains main components consisting of locust bean gum and xanthan gum only, The ratio of the mass of the xanthan gum to the mass of the locust bean gum is 1 or more and 4 or less; The content ratio of the components other than the main component to the total amount of the thickening gelling agent is 20% by mass or less and is determined to satisfy the following conditions (i) and (ii): Cold storage material. (i) The ice storage material is left in an environment of 40°C for four hours or more, and then the container containing the ice storage material is turned sideways in an environment of 40°C for three minutes, after which no separation of the liquid components is visually confirmed. (ii) After the cold storage material is left in an environment of 40°C for four hours or more, and then the container containing the cold storage material is turned sideways in an environment of 40°C for three minutes, no deformation is observed at the interface between the cold storage material and the air, and the interface extends in a direction perpendicular to the horizontal plane.

2. The heat storage material does not include a synthetic polymer produced by crosslinking a polyacrylamide derivative, polyvinyl alcohol, sodium polyacrylate, or sodium polymethacrylate. The heat storage material according to claim 1 .

3. Chemical formula Ag 3 P.O. 4 Silver phosphate, represented by the chemical formula Ag 2 CO 3 and silver oxide represented by the chemical formula AgO, The heat storage material according to claim 1 .

4. The cold storage material according to claim 3 , wherein the silver compound is silver phosphate.

5. The cold storage material according to claim 3 , wherein the silver compound is silver carbonate.

6. The cold storage material according to claim 3 , wherein the silver compound is silver oxide.

7. The molar ratio of the content of the silver compound to the content of the water is 2.64 × 10 -8 Above 3.75 x 10 -4 The cold storage material according to claim 3, wherein:

8. a ratio of the content of the silver compound to the total content of the tetrahydrofuran, the water, and the thickening gelling agent is 0.00050 or more and 0.020 or less on a mass basis; The cold storage material according to claim 3.

9. a ratio of the content of the silver compound to the total content of the tetrahydrofuran, the water, and the thickening gelling agent is 0.0010 or more and 0.010 or less by mass; The heat storage material according to claim 8.

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