Cold storage material composition

Abstract

To provide a cold storage material composition that exhibits superior capability in holding and maintaining temperature within a temperature region of -20°C or less.SOLUTION: A cold storage material composition includes a four-component eutectic composition comprising water, two types of inorganic salts, and urea, where the difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition is 0.5°C or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Conventionally, there has been an accelerating trend toward eliminating dry ice in the temperature range for refrigerated transportation. To this end, various heat storage material compositions or cold storage material compositions (hereinafter collectively referred to as "cold storage material compositions") that utilize latent heat have become known, and these cold storage material compositions are used in various fields, such as air conditioning and heating systems or the storage and transportation of goods. One example of such a cold storage material composition is a cold storage material containing water, sodium chloride, ammonium chloride, and a crystalline powder that is poorly soluble in an aqueous solution of an inorganic salt (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-078163 Summary of the Invention [Problem to be solved by the invention]

[0004] The qualities required of a cold storage material composition used for refrigerated transportation include not only the temperature retention ability to maintain the temperature of an object below a specified temperature range, but also the temperature retention ability to maintain temperature-sensitive objects (e.g., fresh food, ice cream, etc.) at a constant temperature for an extended period of time.

[0005] The object of the present invention is to provide a novel cold storage material composition that has excellent temperature retention capability as well as temperature retention ability in the temperature range of -20°C or below. [Means for solving the problem]

[0006] As a result of extensive research to solve the above problems, the present inventors have found a novel cold storage material composition having the following features. That is, the present invention has the following features. <1> A cold storage material composition comprising a four-component eutectic composition consisting of water, two types of inorganic salts, and urea, wherein the difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition is within 0.5°C. <2> The urea is contained in an amount of 3.2% by weight or more based on 100% by weight of the cold storage material composition containing the four-component eutectic composition. <1> The cold storage material composition according to claim 1. <3> the eutectic temperature of the four-component eutectic composition is at least 2.0°C lower than the eutectic temperature of a three-component eutectic composition consisting of water and the two inorganic salts; <1> or <2> The cold storage material composition according to claim 1. <4> The latent heat of the cold storage material composition is 220 J / g or more. <1> ~ <3> The cold storage material composition according to any one of the above items. <5> The two inorganic salts are selected from the group consisting of sodium chloride, potassium chloride, and ammonium chloride. <1> ~ <4> The cold storage material composition according to any one of the above items. <6> The content of each component in 100% by weight of the cold storage material composition containing the four-component eutectic composition is: Water: 71.0~74.0% by weight; Sodium chloride: 18.0-20.0% by weight; Potassium chloride: 3.0-5.5% by weight; Urea: 3.2~5.5% by weight; That is, <1> ~ <5> The cold storage material composition according to any one of the above items. <7> The content of each component in 100% by weight of the cold storage material composition containing the four-component eutectic composition is: Water: 69.0~77.0% by weight; Sodium chloride: 13.5-18.0% by weight; Ammonium chloride: 5.0-10.0% by weight; Urea: 3.5~7.5% by weight; That is, <1> ~ <5> The cold storage material composition according to any one of the above items. <8> The content of each component in 100% by weight of the cold storage material composition containing the four-component eutectic composition is: Water: 70.0~74.5% by weight; Potassium chloride: 8.5-9.5% by weight; Ammonium chloride: 8.5-9.5% by weight; Urea: 7.0~12.5% ​​by weight That is, <1> ~ <5> The cold storage material composition according to any one of the above items. <9> Further, a nucleating agent containing a fatty acid alkali metal salt is contained. <1> ~ <8> The cold storage material composition according to any one of the above items. <10> The fatty acid alkali metal salt includes one or more selected from sodium laurate and sodium stearate. <9> The cold storage material composition according to claim 1. [Effects of the Invention]

[0007] According to one aspect of the present invention, a cold storage material composition having excellent temperature retention and temperature maintenance capabilities in a temperature range of −20° C. or lower can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] This is a graph plotting the temperature of a refrigerant composition containing a four-component eutectic composition against time when a solidified refrigerant composition according to one embodiment of the present invention is placed in a thermostatic chamber and the temperature of the thermostatic chamber is then increased from an extremely low temperature (e.g., -60°C) at a constant heating rate. [Figure 2] 1 is a graph showing changes in melting behavior of regenerator compositions according to examples of the present invention and comparative examples. [Figure 3] 4 is a graph showing the change in melting behavior of a regenerator material composition according to a comparative example of the present invention. [Figure 4] 4 is a graph showing the change in melting behavior of a regenerator material composition according to a comparative example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described in detail below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments and examples obtained by appropriately combining the technical means disclosed in different embodiments and examples. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, the term "A to B" representing a numerical range means "greater than or equal to A (including A and greater than A) and less than or equal to B (including B and less than B)."

[0010] [1. Cold storage material composition] A cold storage material composition according to one embodiment of the present invention includes a four-component eutectic composition consisting of water, two types of inorganic salts, and urea, and the difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition is within 0.5°C. When the cold storage material composition has the above-mentioned configuration, it has excellent temperature retention and temperature maintenance capabilities in a temperature range of -20°C or lower. For example, when the melting temperature of the cold storage material composition is -20°C or lower, it can be said that the cold storage material composition has excellent temperature retention capabilities in a temperature range of -20°C or lower.

[0011] The cold storage material composition according to one embodiment of the present invention can be used as a latent heat type cold storage material by absorbing thermal energy when the cold storage material composition undergoes a phase transition from a solidified state (solid) to a molten state (liquid) (in other words, when melting). The cold storage material composition according to one embodiment of the present invention can also be called a melting type latent heat cold storage material composition.

[0012] <1-1. Components contained in the cold storage material composition> In this specification, a composition is defined as having a multicomponent eutectic (more specifically, an (n+1)-component eutectic) composition when it contains (i) water and (ii) compounds C1,..., and compounds Cn (n is an integer of 2 or greater), in other words, when it contains water and n compounds, and when it satisfies both of the following conditions (1) and (2): Furthermore, a composition is defined as being a multicomponent eutectic (more specifically, an (n+1)-component eutectic) composition when it consists of (i) water and (ii) compounds C1,..., and compounds Cn (n is an integer of 2 or greater), in other words, when it consists of water and n compounds, and when it satisfies both of the following conditions (1) and (2):

[0013] Condition (1) When at least two compositions are obtained by varying the concentration ratio of any one compound among compounds C1... and compounds Cn in a composition (specifically, the weight ratio of the compound in the composition) and / or the weight percentage of the compound by a predetermined amount, the temperatures at which a portion or the entirety of each composition melts fall within a certain range among the obtained compositions.

[0014] Condition (2) The temperature at which a composition containing water and n compounds melts in part or in whole is lower than the temperature at which a composition containing water and n-1 compounds obtained by removing any one compound from the composition melts in part or in whole.

[0015] Herein, "the temperature at which a part or all of the composition melts" is also referred to as "temperature X" in the present specification.

[0016] In this specification, the conditions (1) and (2) are more specifically defined as follows.

[0017] Regarding condition (1), when a composition containing water and n compounds is obtained by varying the content of any one or more compounds in the composition by at least 2% by weight to obtain at least two compositions, condition (1) is defined as being satisfied when the range of compound contents is such that the temperature difference between the temperature X of each composition between the obtained compositions is within 1.0°C.

[0018] Condition (2) is defined as being satisfied when the temperature X of a composition containing water and n compounds is lower by 1°C or more than the temperature X of a composition containing water and n-1 compounds obtained by removing any one compound from the composition.

[0019] The method for measuring the "temperature X" of a composition will be described below. First, a solidified composition is placed in a thermostatic chamber, and the temperature of the thermostatic chamber is increased from a cryogenic temperature (e.g., -60°C) at a constant rate. The temperature change of the composition during this period is measured, and a graph is created in which the temperature of the composition (Y axis) is plotted against time (X axis). In this graph, the temperature of the composition can change, for example, in the following order (1) to (4): (1) it increases at a constant or approximately constant rate from a cryogenic temperature (e.g., -60°C) to a certain temperature (temperature TX1); (2) it remains almost constant from temperature TX1 to a certain temperature (temperature TX2) due to the latent heat of the composition; (3) it temporarily increases slowly at temperature TX2, after which the rate of increase gradually decreases and it remains almost constant again until it reaches a certain temperature (temperature TX3); (4) it increases sharply at temperature TX3. In this specification, the intermediate temperature between temperatures TX1 and TX2 is defined as "temperature X." Depending on the composition, there may be no temperature change from temperature TX2 to temperature TX3. That is, depending on the composition, there may be cases where temperature TX2 and temperature TX3 are the same. Furthermore, when the composition satisfies the above-mentioned conditions (1) and (2), that is, when the composition contains a multi-component eutectic composition or is a multi-component eutectic composition, the above temperature X may also be referred to as the "eutectic temperature" described later.

[0020] A cold storage material composition according to one embodiment of the present invention contains two types of inorganic salts. Examples of the inorganic salts include inorganic chlorides, inorganic bromides, sulfates, nitrates, formates, inorganic hydroxides, inorganic iodides, ammonium salts, and metal salts such as calcium salts. Among these, ammonium salts, inorganic chlorides, and inorganic bromides are preferred as the inorganic salts, and inorganic chlorides are more preferred. As the two types of inorganic salts, a combination of multiple salts from the above-mentioned inorganic salts may be used, but it is preferred that both types of salts have the same ionic species, and it is more preferred that both types of salts are inorganic chlorides.

[0021] Examples of the chloride salt include sodium chloride, calcium chloride, ammonium chloride, lithium chloride, potassium chloride, magnesium chloride, zinc chloride, and aluminum chloride. Among these, two types selected from the group consisting of sodium chloride, potassium chloride, and ammonium chloride are preferred from the viewpoints of safety and low cost, high solubility and resistance to precipitation, and easy availability.

[0022] Through extensive research, the present inventors independently discovered the novel finding that a composition consisting of water, sodium chloride, and potassium chloride, a composition consisting of water, sodium chloride, and ammonium chloride, and a composition consisting of water, potassium chloride, and ammonium chloride are each a ternary eutectic composition. That is, in one embodiment of the present invention, the two inorganic salts contained in the quaternary eutectic composition may be sodium chloride and potassium chloride (eutectic temperature of ternary eutectic composition: −22.5 to −23.5° C.), sodium chloride and ammonium chloride (eutectic temperature of ternary eutectic composition: −24.0 to −25.0° C.), or potassium chloride and ammonium chloride (eutectic temperature of ternary eutectic composition: −17.0 to −18.0° C.).

[0023] The water in the cold storage material composition according to one embodiment of the present invention may be water that can be used as drinking water, and may be, for example, soft water, hard water, or pure water.

[0024] During the course of intensive research, the present inventors investigated whether compositions obtained by individually adding various compounds containing nitrogen atoms in their molecules to a ternary eutectic composition consisting of, for example, water, sodium chloride, and potassium chloride, are quaternary eutectic compositions according to the above-mentioned definition. As a result, they independently and surprisingly discovered that at least a composition containing urea satisfies the above-mentioned definition and is a quaternary eutectic composition. On the other hand, compositions obtained by adding amino acids such as glycine and alanine, which also contain nitrogen atoms in their molecules like urea, do not satisfy condition (1), as shown in Figures 3 and 4, and therefore are not quaternary eutectic compositions. In other words, the quaternary eutectic composition according to one embodiment of the present invention forms a quaternary eutectic system by including urea. Furthermore, glycine, alanine, etc., can lower the melting point of the composition depending on the amount added. Therefore, glycine, alanine, etc. can be considered melting point depressants.

[0025] The content of urea in 100% by weight of the cold storage material composition containing the quaternary eutectic composition is preferably 3.2% by weight or more, more preferably 3.5% by weight or more. The upper limit of the urea content is preferably 12.5% ​​by weight or less, and more preferably 12.3% by weight or less. By setting the urea content within the above range, the constant temperature retention time, which indicates the temperature maintenance ability of the obtained cold storage material composition, is improved.

[0026] In one embodiment, the content of each component in 100% by weight of the cold storage material composition containing the four-component eutectic composition may be any of the compositions shown in (1) to (3) below.

[0027] (1) Water: 71.0~74.0% by weight; Sodium chloride: 18.0-20.0% by weight; Potassium chloride: 3.0-5.5% by weight; Urea: 3.2~5.5% by weight; (2) Water: 69.0~77.0% by weight; Sodium chloride: 13.5-18.0% by weight; Ammonium chloride: 5.0-10.0% by weight; Urea: 3.5~7.5% by weight; (3) Water: 70.0~74.5% by weight; Potassium chloride: 8.5 to 9.5% by weight Ammonium chloride: 8.5 to 9.5% by weight Urea: 7.0~12.5% ​​by weight; With the above-mentioned configuration, the difference between the melting temperature of the obtained cold storage material composition and the eutectic temperature of the four-component eutectic composition tends to be within 0.5° C. Among these configurations (1) to (3), from the viewpoints of environmental compatibility and economy, the four-component eutectic composition having the composition (1) that does not contain ammonium chloride is preferred.

[0028] As described below, the cold storage material composition according to one embodiment of the present invention is filled into a container, a bag, or the like to form a cold storage material, and the cold storage material can be placed in a transport container for use. However, if the container or the like forming the cold storage material is damaged during transportation or carrying, the cold storage material composition filled in the container will leak from the damaged container. In this case, there is a concern that the item subject to temperature control may be contaminated, rendering the item unusable.

[0029] Therefore, in order to minimize leakage of the ice storage material composition even if a container filled with the ice storage material composition is damaged during transportation or carrying, it is preferable that the ice storage material composition of one embodiment of the present invention contains a thickener and is in a solid state (including a gel state).

[0030] The thickener is not particularly limited, but examples thereof include water-absorbent resins (e.g., starch-based, acrylate-based, poval-based, and carboxymethyl cellulose-based), gelatin, agar, silica gel, xanthan gum, gum arabic, guar gum, carrageenan, cellulose, and konjac.

[0031] Examples of the nonionic thickener include guar gum, dextrin, polyvinylpyrrolidone, and hydroxyethyl cellulose.

[0032] Since the cold storage material composition according to one embodiment of the present invention contains two types of inorganic salts, precipitation of the inorganic salts may occur over time due to temperature changes depending on the concentrations of the contained inorganic salts. When the cold storage material composition contains a thickener, the thickener not only makes the cold storage material composition gel-like, but also efficiently disperses the dissolved ions of the inorganic salts, thereby enabling the inorganic salts to remain within the system.

[0033] Among the thickeners exemplified above, nonionic thickeners that do not affect the inorganic ions dissolved in the ice storage material composition are preferred, and among nonionic thickeners, hydroxyethyl cellulose is particularly preferred because of its excellent gel stability and environmental compatibility.

[0034] When the cold storage material composition contains a thickener, it has the following advantages (1) to (3): (1) the thickener does not affect the melting and solidification behavior of the cold storage material composition, and the cold storage material composition can maintain a high latent heat; (2) there is no separation of the solid and liquid phases in the cold storage material composition even after a heat cycle test at the environmental temperature where the cold storage material composition is expected to be used; (3) it is possible to reduce the environmental impact in the event of leakage due to damage to the container or bag, etc., and the workload during recovery.

[0035] The optimum amount of thickener to be added varies depending on the type used, but from the viewpoints of (1) preventing aggregation and precipitation of compounds contained in the cold storage material composition, (2) not requiring special pumps or the like during production and transportation of the cold storage material composition, and (3) providing good handleability of the cold storage material composition, it is usually preferable to add 0.1 to 10 parts by weight, and more preferably 0.2 to 5.0 parts by weight, per 100 parts by weight of the cold storage material composition (aqueous solution) containing the quaternary eutectic composition.By adding 0.2 to 5.0 parts by weight of hydroxyethyl cellulose, the cold storage material composition can become a transparent gel with reduced fluidity.

[0036] The cold storage material composition according to one embodiment of the present invention preferably contains a fatty acid alkali metal salt as a nucleating agent. By including the fatty acid alkali metal salt, the cold storage material composition freezes at higher temperatures, improving its cold insulation effect. The fatty acid alkali metal salt is not particularly limited, but may be one or more selected from sodium laurate, potassium laurate, lithium laurate, calcium laurate, magnesium laurate, barium laurate, lithium terephthalate, sodium terephthalate, potassium terephthalate, calcium oxalate, sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, sodium octacosanoate, calcium octacosanoate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate, barium stearate, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, sodium oleate, potassium oleate, potassium metaphosphate, sodium silicate, potassium isostearate, and the like. Among these, it is preferable to include at least one selected from sodium laurate and sodium stearate, from the viewpoint of improving the cold insulation effect of the obtained cold storage material composition.

[0037] The content of the nucleating agent is preferably 0.1 to 5.0 parts by weight, more preferably 0.5 to 4.0 parts by weight, and even more preferably 0.8 to 2.0 parts by weight, relative to 100 parts by weight of the cold storage material composition (aqueous solution) containing the quaternary eutectic composition. If the content of the nucleating agent is within the above range, when the cold storage material composition freezes, freezing begins without passing through a supercooled state, so there is no need to drastically lower the temperature of the freezer used to freeze the cold storage material composition, and the time until freezing is complete is stabilized, so the cold storage material composition can be easily frozen. This is sometimes referred to as having excellent freezing ease.

[0038] In addition to the above components, the cold storage material composition according to one embodiment of the present invention may contain, as necessary, a phase separation inhibitor (e.g., oleic acid), a fragrance, a colorant, an antibacterial agent, a high molecular weight polymer, other organic compounds, or other inorganic compounds.

[0039] <1-2. Physical properties of the cold storage material composition> In the cold storage material composition according to one embodiment of the present invention, the difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition is within 0.5°C.

[0040] In this specification, the "melting temperature" of a cold storage material composition means "the temperature that the solid cold storage material composition exhibits when it melts and liquefies."

[0041] The melting temperature of the regenerator composition can be measured by placing a measurement sample in a thermostatic chamber equipped with a commercially available temperature control unit, raising or lowering the temperature of the thermostatic chamber at a constant rate, and monitoring the sample temperature using a thermocouple.

[0042] The "melting temperature" of the cold storage material composition will be explained in more detail with reference to FIG. 1. FIG. 1 is a graph plotting the temperature of a cold storage material composition according to one embodiment of the present invention in a solidified state against time when the temperature of the thermostatic bath is increased from an extremely low temperature at a constant rate of temperature increase. As shown in FIG. 1, compared to the temperature of the thermostatic bath, which increases at a constant rate, the temperature of the cold storage material composition changes in the following order (1) to (4): (1) increases at a constant or approximately constant rate from -60°C to a certain temperature (temperature T1); (2) hardly changes from temperature T1 to a certain temperature (temperature T2) due to the latent heat of the cold storage material composition; (3) after a temporary gradual increase is observed at temperature T2, the rate of increase gradually decreases and hardly changes again until a certain temperature (temperature T3) is reached. (4) A sharp rise occurs at temperature T3. In this specification, temperature T1 is referred to as the "melting start temperature," and temperature T3 is referred to as the "melting end temperature." A linear approximation line (L) is drawn for the temperature history in the range from temperature T1 to temperature T3, and temperature T4 is defined as the temperature at the intersection of the linear approximation line (L) and time S4, which is intermediate between time S1 when temperature T1 is reached and time S3 when temperature T3 is reached. In this specification, temperature T4 is defined as the "melting temperature." In addition, the intermediate temperature between temperature T1 and temperature T2 is defined as temperature T5. In this specification, temperature T5 is defined as the "eutectic temperature" of the four-component eutectic composition contained in the cold storage material composition.

[0043] The present inventors independently discovered the following novel finding during their extensive research. In FIG. 1, which is a graph showing the temperature change (melting behavior) during melting of a cold storage material composition, the temperature of the cold storage material composition changes in the order of (1) to (4), as described above. Furthermore, as described above, temperature T5 can be said to be the "eutectic temperature" of the four-component eutectic composition contained in the cold storage material composition. In other words, the temperature change portion from temperature T1 to temperature T2, where there is almost no change, can also be said to be a temperature change portion derived from the eutectic temperature of the four-component eutectic composition. On the other hand, the temperature of the cold storage material composition again becomes almost unchanged around temperature T3. The present inventors speculated that the temperature change portion, where there is almost no change and which can be observed around temperature T3, is derived from the three-component eutectic composition inherent in the cold storage material composition (for example, derived from the eutectic temperature of the three-component eutectic composition). That is, the cold storage material composition according to one embodiment of the present invention may exhibit both a temperature change resulting from the eutectic temperature of the four-component eutectic composition and a temperature change resulting from the eutectic temperature of the three-component eutectic composition during melting. The temperature change portion with little change during melting of the cold storage material composition is also referred to as a "shoulder." When the cold storage material composition exhibits two temperature change portions with little change during melting, the melting behavior of the cold storage material composition can also be referred to as a "double shoulder." It can also be said that the more temperature change portions resulting from the eutectic temperature of the three-component eutectic composition in the melting behavior of the cold storage material composition, the more likely a "double shoulder" is to be observed. In other words, the cold storage material composition according to one embodiment of the present invention may contain a four-component eutectic composition and a three-component eutectic composition, and the four-component eutectic composition and the three-component eutectic composition may coexist within the cold storage material composition. Furthermore, the eutectic temperature of the three-component eutectic composition is higher than the eutectic temperature of the four-component eutectic composition. Therefore, the greater the temperature change portion due to the eutectic temperature of the quaternary eutectic composition relative to the temperature change portion due to the eutectic temperature of the ternary eutectic composition, the longer the temperature can be maintained at a lower temperature, in other words, the better the temperature maintenance ability in the temperature range below -20°C. Here, it is presumed that the melting temperature of the regenerator material composition changes depending on the ratio between the temperature change portion due to the eutectic temperature of the quaternary eutectic composition and the temperature change portion due to the ternary eutectic composition.In other words, it is presumed that the melting temperature of the cold storage material composition varies depending on the ratio of the four-component eutectic composition to the three-component eutectic composition in the cold storage material composition. For example, in the melting behavior of the cold storage material composition, the greater the temperature change portion resulting from the eutectic temperature of the four-component eutectic composition, the smaller the slope of the linear approximation line (L) described above. Therefore, it is presumed that the melting temperature of the cold storage material composition decreases and the temperature difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition contained in the cold storage material composition becomes smaller. In other words, the smaller the temperature difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition contained in the cold storage material composition, the more advantageous the cold storage material composition is in its ability to maintain temperature in a temperature range of -20°C or below. Furthermore, in the melting behavior of the cold storage material composition, the smaller the temperature change portion due to the eutectic temperature of the ternary eutectic composition, the less likely the above-mentioned "double shoulder" is to be observed, and the cold storage material composition has the advantage of having excellent temperature maintenance ability in the temperature range of -20°C or below. Furthermore, in the melting behavior of the cold storage material composition, if the temperature change portion due to the eutectic temperature of the ternary eutectic composition is very small or not at all, the temperature change from temperature T2 to temperature T3 may be very difficult to observe or may not be observed at all (in other words, there may be cases where temperature T2 and temperature T3 are the same or nearly the same). In the melting behavior of the cold storage material composition, the less likely the temperature change from temperature T2 to temperature T3 is to be observed, the more excellent the cold storage material composition's temperature maintenance ability in the temperature range of -20°C or below.

[0044] The difference between the melting temperature of the cold storage material composition according to one embodiment of the present invention and the eutectic temperature of the four-component eutectic composition contained in the cold storage material composition is preferably 0.5° C. or less, more preferably 0.4° C. or less, more preferably 0.3° C. or less, even more preferably 0.2° C. or less, and particularly preferably 0.1° C. or less. When the difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition is 0.5° C. or less, the cold storage material composition has the advantage of excellent temperature maintenance ability in the temperature range of −20° C. or less.

[0045] In one embodiment of the present invention, the lower the eutectic temperature of the four-component eutectic composition contained in the cold storage material composition is compared to the eutectic temperature of the three-component eutectic composition consisting of water and the two inorganic salts, the more excellent the temperature-maintaining ability of the cold storage material composition in a temperature range of −20° C. or less. In one embodiment of the present invention, the eutectic temperature of the four-component eutectic composition contained in the cold storage material composition is preferably at least 2.0° C. lower, more preferably at least 3.0° C. lower, and even more preferably at least 4.0° C. lower than the eutectic temperature of the three-component eutectic composition consisting of water and the two inorganic salts.

[0046] In the cold storage material composition according to one embodiment of the present invention, the latent heat quantity is preferably 220 J / g or more, more preferably 240 J / g or more, and even more preferably 260 J / g or more. If the latent heat quantity is 220 J / g or more, the cold storage material composition has the advantage of being superior in temperature retention performance and temperature maintenance ability in the temperature range of -20°C. The latent heat quantity of the cold storage material composition can be measured by the method described in the examples.

[0047] In the cold storage material composition according to one embodiment of the present invention, the melting temperature is preferably −20° C. or lower, more preferably −23° C. or lower, and even more preferably −25° C. or lower. When the melting temperature is within the above range, the cold storage material composition can be suitably used in a temperature range of −20° C. or lower. The lower limit of the melting temperature of the cold storage material composition is not particularly limited, and may be, for example, −40° C.

[0048] <1-3. Method for producing the cold storage material composition> In one embodiment of the present invention, the method for preparing the cold storage material composition containing water, two types of inorganic salts, and urea is not particularly limited, and any known method can be used. For example, the two types of inorganic salts and urea can be mixed in advance using a tumbler or ribbon blender, then transferred to a container, water can be poured into the container, and the mixture can be stirred with a mixer while cooling the container. Alternatively, the cold storage material composition can be prepared by preparing aqueous solutions of each inorganic salt and an aqueous solution of urea and mixing them.

[0049] [2. Cold storage material] The cold storage material according to one embodiment of the present invention may be any material that includes the above-described cold storage material composition, and other configurations, materials, etc. are not limited.

[0050] The cold storage material according to one embodiment of the present invention can be used as a latent heat type cold storage material by absorbing thermal energy when the cold storage material composition forming the cold storage material undergoes a phase transition from a solidified state (solid) to a molten state (liquid) (in other words, when melting). The cold storage material according to one embodiment of the present invention can also be called a melting type latent heat cold storage material.

[0051] For example, the cold storage material according to one embodiment of the present invention may be a container, a bag, or the like filled with the above-described cold storage material composition.

[0052] From the viewpoint of preventing leakage due to rust and corrosion caused by the cold storage material composition, the container or bag is preferably formed mainly from a resin (e.g., a synthetic resin), such as polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate, polystyrene, nylon, or polyester.

[0053] These materials may be used alone, or in order to improve heat resistance and barrier properties, two or more of these materials may be used in combination (for example, a multi-layer structure may be used).From the standpoints of handling and cost, it is preferable to use containers or bags made of polyethylene.

[0054] The shape of the container or bag is not particularly limited, but from the viewpoint of efficient heat exchange between the cold storage material composition and the item to be temperature controlled or the space around it via the container or bag, a shape that is thin and ensures a large surface area is preferred. A cold storage material can be formed by filling the container or bag with the cold storage material composition. A more specific example of the container or bag is the container or bag disclosed in JP 2015-78307 A. This document is incorporated herein by reference.

[0055] [3. Transport Container] The transport container according to one embodiment of the present invention may be one that is equipped with the ice storage material according to one embodiment of the present invention described above, and other specific configurations, materials, etc. are not particularly limited.

[0056] The specific configuration of the heat-insulating container may be the configuration disclosed in Japanese Patent Application Laid-Open No. 2015-78307, which is incorporated herein by reference. [Example]

[0057] Hereinafter, one embodiment of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0058] 〔material〕 <Inorganic salts> Sodium chloride (Nippon Salt Manufacturing, refined salt) (eutectic temperature with water -20.9°C) Potassium chloride (manufactured by Manac, potassium chloride) (eutectic temperature with water -10.8°C) Ammonium chloride (manufactured by Toshin Chemical Industry, industrial ammonium chloride) (eutectic temperature with water -15.1°C) <Urea> Urea (Mitsui Chemicals, industrial urea) (does not form a eutectic system with water) Glycine (Fujifilm Wako Pure Chemical Industries, Ltd.) (eutectic temperature with water -3.3°C) Alanine (Fujifilm Wako Pure Chemical Industries, Ltd.) (eutectic temperature with water -2.4°C) <Thickener> Hydroxyethyl cellulose (HEC) (manufactured by Daicel Finechem, HEC Daicel) <Nucleating agent> Potassium laurate (Nitto Kasei Kogyo, KS-3) Potassium myristate (NIKKOL Potassium Myristate MK-140, manufactured by Nikko Chemicals) <Water> drinking tap water

[0059] [Preparation of cold storage material composition] The cold storage material composition was prepared by mixing aqueous solutions of each inorganic salt, an aqueous solution of urea, and, if the cold storage material contains a crystal nucleating agent, an aqueous solution of the nucleating agent. When mixing the thickener, the thickener was dispersed in the aqueous solution in which each compound had been dissolved, and then dissolved by heating the aqueous solution to 40°C or higher.

[0060] Measurements and evaluations in the examples and comparative examples were carried out under the following conditions and methods.

[0061] [Measurement of melting temperature and eutectic temperature] A polypropylene cryovial filled with 1.8 ml of the cold storage composition was placed in a thermostatic chamber (Cryoporter (registered trademark) CS-80CP, ultra-low temperature aluminum block thermostatic chamber, manufactured by Synix Corporation). The melting temperature of the cold storage composition and the eutectic temperature of the four-component eutectic composition were measured according to the following procedures 1 to 4. 1. The temperature in the thermostatic bath was maintained at 20°C for 1 hour; 2. The temperature in the thermostatic chamber was decreased from 20°C to -60°C at a rate of 1.0°C / min; 3. The temperature in the thermostatic chamber was maintained at -60°C for 1 hour; 4. The temperature in the thermostatic chamber was increased from -60°C to 20°C at a rate of 1.0°C / min.

[0062] <Method for calculating the melting temperature of the regenerator composition and the eutectic temperature of the quaternary eutectic composition> Figure 1 shows a graph plotting the temperature of the cold storage material composition in the thermostatic bath against time for the process 4. As shown in Figure 1, compared to the temperature of the thermostatic bath, which rose at a constant rate, the temperature of the cold storage material composition changed in the following order (1) to (4): (1) it rose from -60°C to a certain temperature (temperature T1) at a constant or approximately constant rate; (2) it barely changed from temperature T1 to a certain temperature (temperature T2) due to the latent heat of the cold storage material composition; (3) it temporarily rose slowly at temperature T2, after which the rate of rise gradually decreased and it barely changed again until a certain temperature (temperature T3) was reached; and (4) it rose sharply at temperature T3. In this specification, temperature T1 is referred to as the "melting start temperature" and temperature T3 is referred to as the "melting end temperature." A linear approximation line (L) was drawn for the temperature history in the range from temperature T1 to temperature T3, and the temperature at the intersection of the linear approximation line (L) and time S4, which is midway between time S1 when temperature T1 was reached and time S3 when temperature T3 was reached, was designated as temperature T4, and temperature T4 was defined as the "melting temperature." Further, the midway temperature between temperatures T1 and T2 was designated as temperature T5, and temperature T5 was defined as the "eutectic temperature" of the four-component eutectic composition contained in the cold storage material composition.

[0063] Furthermore, the melting temperature of the regenerator material composition and the eutectic temperature of the four-component eutectic composition were evaluated based on the following criteria.

[0064] (Melting temperature criteria) A: The difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition is within 0.5°C B: The difference between the melting temperature of the regenerator composition and the eutectic temperature of the quaternary eutectic composition exceeds 0.5°C (4-component eutectic temperature criterion) A: The eutectic temperature of the quaternary eutectic composition is 2.0°C or more lower than the eutectic temperature of the ternary eutectic composition. B: The eutectic temperature of the quaternary eutectic composition is not lower than the eutectic temperature of the ternary eutectic composition, or is lower by less than 2.0°C. <Measurement of the latent heat of the cold storage material composition> Using a differential scanning calorimeter (DSC) (Hitachi High-Tech Corporation, NEXTA DSC200AS), the ice storage material composition was measured by raising and lowering the temperature from 0.0°C to -70°C and from -70°C to 0.0°C at a rate of 2.0°C / min, and the latent heat of the ice storage material composition was calculated using the analysis software provided with the device.

[0065] (Latent heat amount determination criteria) A: Latent heat of the cold storage material composition is 220 J / g or more B: Latent heat of the cold storage material composition is less than 220 J / g

[0066] <Overall Judgment Criteria> A: All of the melting temperature criteria, four-component eutectic temperature criteria, and latent heat criteria are A. B: At least one of the latent heat criteria, four-component eutectic temperature criteria, and latent heat criteria is B

[0067] <Evaluation result 1> Tables 1 to 3 show the compositions of the evaluated cold storage material compositions and quaternary eutectic compositions, as well as the evaluation results.

[0068] [Table 1]

[0069] [Table 2]

[0070] The results of Examples 1 to 16 are shown in Table 1. The results of Comparative Examples 1 to 11 are shown in Table 2. A cold storage material composition containing a ternary eutectic composition that does not contain urea is shown as Reference Example 1. The cold storage material compositions of Examples 1 to 16 and Comparative Examples 1 to 11 contain sodium chloride and potassium chloride as inorganic salts. The cold storage material compositions of Examples 1 to 16 were judged as A for the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition. On the other hand, the cold storage material compositions of Comparative Examples 1 to 5 were judged as B for the melting temperature of the cold storage material composition. Therefore, it can be said that the cold storage material compositions of Examples 1 to 16 have excellent temperature retention and temperature maintenance capabilities in a temperature range of -20°C or lower.

[0071] To demonstrate the effect of adding urea on improving constant-temperature maintenance performance, Figure 2 shows the change in melting behavior when the temperature of cold storage material compositions containing 0 wt% (Reference Example 1), 0.6 wt% (Comparative Example 3), 1.2 wt% (Comparative Example 4), 2.5 wt% (Comparative Example 5), and 3.2 wt% (Example 2) urea was increased at a constant heating rate while the weight ratios of water, sodium chloride, and potassium chloride were kept constant. As shown in Figure 2, the cold storage material compositions containing urea exhibited a eutectic temperature derived from the four-component eutectic composition. As the amount of urea added increased, the amount of the portion with little temperature change due to the eutectic temperature derived from the four-component eutectic composition increased (the time period became very long). In particular, the cold storage material composition of Example 2, in which the difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition was within 0.5°C, exhibited a very large portion (the time period became very long) with little temperature change due to the eutectic temperature derived from the four-component eutectic composition, demonstrating excellent temperature maintenance capability in the temperature range below -20°C.

[0072] FIG. 3 shows the change in melting behavior when the weight ratio of water, sodium chloride, and potassium chloride was constant and the weight ratio of glycine, a type of amino acid that has a urea atom in its molecule like urea, was changed to 0 wt % (Reference Example 1), 1.2 wt % (Comparative Example 6), 2.5 wt % (Comparative Example 7), and 3.2 wt % (Comparative Example 8). The glycine content differs by 2 wt % between Comparative Example 6 and Comparative Example 8. As can be seen from FIG. 3, the temperature difference between the temperature X of Comparative Example 6 and the temperature X of Comparative Example 8 exceeds 1°C. Therefore, it was confirmed that the compositions of Comparative Examples 6 to 8, which contain glycine instead of urea, do not satisfy the above-mentioned condition (1) and are not quaternary eutectic compositions.

[0073] Similarly, FIG. 4 shows the change in melting behavior when the weight ratio of alanine, a type of amino acid, is set to 0 wt% (Reference Example 1), 1.2 wt% (Comparative Example 9), 2.5 wt% (Comparative Example 10), and 3.2 wt% (Comparative Example 11). The alanine content differs by 2 wt% between Comparative Example 9 and Comparative Example 11. As can be seen from FIG. 4, the temperature difference between the temperature X of Comparative Example 9 and the temperature X of Comparative Example 11 exceeds 1°C. Therefore, it was confirmed that the compositions of Comparative Examples 9 to 11, which contain alanine instead of urea, do not satisfy the above-mentioned condition (1), and are not quaternary eutectic compositions.

[0074] [Table 3]

[0075] The results of Examples 17 to 23 and Comparative Examples 12 to 19 are shown in Table 3. A cold storage material composition containing a ternary eutectic composition that does not contain urea is shown as Reference Example 2. The cold storage material compositions of Examples 17 to 23 and Comparative Examples 12 to 19 contain sodium chloride and ammonium chloride as inorganic salts. The cold storage material compositions of Examples 17 to 23 were evaluated as A for the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition. On the other hand, the cold storage material compositions of Comparative Examples 12 to 19 were evaluated as B for the melting temperature of the cold storage material composition. Therefore, it can be said that the cold storage material compositions of Examples 17 to 23 have excellent temperature retention and temperature maintenance capabilities in a temperature range of -20°C or lower.

[0076] [Table 4]

[0077] The results of Examples 24 to 31 and Comparative Examples 20 to 25 are shown in Table 4. A cold storage material composition containing a ternary eutectic composition that does not contain urea is shown as Reference Example 3. The cold storage material compositions of Examples 24 to 31 and Comparative Examples 20 to 25 contain potassium chloride and ammonium chloride as inorganic salts. The cold storage material compositions of Examples 24 to 31 were evaluated as A for the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition. On the other hand, the cold storage material compositions of Comparative Examples 20 to 25 were evaluated as B for the melting temperature of the cold storage material composition. Therefore, it can be said that the cold storage material compositions of Examples 24 to 31 have excellent temperature retention and temperature maintenance capabilities in a temperature range of -20°C or lower.

[0078] [Freezing test] A polypropylene cryovial filled with 1.8 ml of the cold storage material composition was used as an evaluation sample and placed in a thermostatic chamber (Cryoporter (registered trademark) CS-80CP, ultra-low temperature aluminum block thermostatic chamber, manufactured by Synix Co., Ltd.) This cold storage material composition was subjected to a "freezing test" according to the following procedure. 1. The temperature inside the thermostatic chamber was maintained at 20°C for 1 hour. The temperature in the thermostatic chamber was decreased from 2.20°C to the freezing test temperatures (-35°C, -34°C, -33°C, -32°C, -31°C, -30°C) at a rate of 1.0°C / min. 3. The temperature in the thermostatic chamber was maintained at the freezing test temperature for 2 hours; The temperature in the thermostatic chamber was increased to 4.20°C at a rate of 1°C / min.

[0079] (How to confirm freezing) In the process of step 4, by comparing with the temperature rise plot against time of ethanol placed in the thermostatic bath as a blank, the presence or absence of a region corresponding to (2) in Figure 1 was confirmed, and if the region (2) remained for 5 minutes or more, it was determined that freezing had occurred.

[0080] (Freezing test criteria) A: All five samples were frozen. B: Three or four of the five samples were frozen. C: Fewer than 3 of the 5 samples were frozen

[0081] <Evaluation result 2> The results of the freezing test are shown in Table 5.

[0082] [Table 5]

[0083] As shown in Table 5, all of the cold storage material compositions froze at temperatures between -35°C and -33°C. Among these, the cold storage material compositions containing potassium laurate or potassium myristate as nucleating agents froze even in tests at -31°C and -30°C, demonstrating that they can be frozen at temperatures within a temperature difference of -5°C from the melting temperature and have excellent freezing ease. In particular, all samples of the cold storage material composition containing potassium myristate froze even in tests at -31°C and -30°C, demonstrating that they are particularly excellent in freezing ease. [Industrial Applicability]

[0084] The cold storage material composition according to one embodiment of the present invention enables temperature-controlled items, whose controlled temperature is −20° C. or lower, to be stored or transported within the controlled temperature range of the temperature-controlled items under specific environments. Therefore, one embodiment of the present invention can be suitably used for storing and transporting, for example, cells, pharmaceuticals, regenerative cells, specimens, or foods.

Claims

1. A cold storage material composition, a quaternary eutectic composition comprising water, two inorganic salts, and urea; A cold storage material composition, wherein the difference between the melting temperature of the cold storage material composition and the eutectic temperature of the four-component eutectic composition is within 0.5°C.

2. 2. The cold storage material composition according to claim 1, wherein the cold storage material composition contains 3.2% by weight or more of the urea based on 100% by weight of the cold storage material composition containing the four-component eutectic composition.

3. 2. The regenerator material composition according to claim 1, wherein the eutectic temperature of the four-component eutectic composition is at least 2.0°C lower than the eutectic temperature of a three-component eutectic composition consisting of water and the two inorganic salts.

4. The cold storage material composition according to claim 1, wherein the cold storage material composition has a latent heat quantity of 220 J / g or more.

5. 2. The cold storage material composition according to claim 1, wherein the two types of inorganic salts are selected from the group consisting of sodium chloride, potassium chloride, and ammonium chloride.

6. The content of each component in 100% by weight of the cold storage material composition containing the four-component eutectic composition is: Water: 71.0-74.0% by weight; Sodium chloride: 18.0 to 20.0% by weight; Potassium chloride: 3.0 to 5.5% by weight; Urea: 3.2-5.5% by weight; The cold storage material composition according to claim 5,

7. The content of each component in 100% by weight of the cold storage material composition containing the four-component eutectic composition is: Water: 69.0-77.0% by weight; Sodium chloride: 13.5 to 18.0% by weight; Ammonium chloride: 5.0 to 10.0% by weight; Urea: 3.5-7.5% by weight; The cold storage material composition according to claim 5,

8. The content of each component in 100% by weight of the cold storage material composition containing the four-component eutectic composition is: Water: 70.0-74.5% by weight; Potassium chloride: 8.5 to 9.5% by weight; Ammonium chloride: 8.5 to 9.5% by weight; Urea: 7.0-12.5% ​​by weight The cold storage material composition according to claim 5,

9. The cold storage material composition according to any one of claims 1 to 8, further comprising a fatty acid alkali metal salt as a nucleating agent.

10. The heat storage material composition according to claim 9, wherein the fatty acid alkali metal salt comprises at least one selected from the group consisting of sodium laurate and sodium stearate.

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