Humidity conditioning material and humidity conditioning material with packaging material

Abstract

This humidity conditioning material is provided with: a water-absorbing body containing a water-absorbing material; and, a humidity conditioning component, inherent in the water-absorbing material, for absorbing or releasing moisture. The humidity conditioning component contains a metal salt having a deliquescence point within a relative humidity range of 30-80% RH, inclusive.

Description

Humidity control materials and humidity control materials with packaging

[0001] This disclosure relates to a humidity conditioner and a humidity conditioner with packaging. This application claims priority based on Japanese Patent Application No. 2021-085885 filed on May 21, 2021, and Japanese Patent Application No. 2021-156223 filed on September 27, 2021, the contents of which are incorporated herein by reference.

[0002] Compared to commonly used desiccants such as type B silica gel, the humidity conditioner has a high humidity control ability over a wide range of humidity from low to high, and can therefore be used in a wide range of applications.

[0003] Patent Document 1 discloses a hygroscopic composition containing at least one of sodium acetate and potassium acetate and a water-absorbent binder, in which the ratio of the total amount of sodium acetate and potassium acetate (Ac) to the amount of water-absorbent binder (B) (Ac:B [mass ratio]) is in the range of 2:3 to 4:1. This makes it possible to provide a hygroscopic composition that uses sodium acetate and / or potassium acetate, which are non-halogen inorganic salts, and that is inexpensive, has high hygroscopicity, and is highly safe with little risk of metal rust or the like.

[0004] JP 2012-245489 A

[0005] Conventional humidity-conditioning materials have a problem in that they are difficult to use in applications where it is important to have high humidity-conditioning ability in a specific humidity range.

[0006] One aspect of the present disclosure has been made in view of the above problem, and has an object to provide a humidity conditioner and a humidity conditioner with packaging material that can be used in applications where it is important to have high humidity control ability in a specific humidity range, for example.

[0007] A humidity-conditioning material according to one embodiment of the present disclosure comprises a water-absorbing body containing a water-absorbing material, and a humidity-conditioning component that is present in the water-absorbing material and absorbs or releases moisture, and the humidity-conditioning component includes a metal salt that has a deliquescence point within a relative humidity range of 30% RH or more and 80% RH or less.

[0008] A humidity conditioner with packaging material according to another embodiment of the present disclosure includes the humidity conditioner according to the embodiment of the present disclosure and a moisture-permeable packaging material that packages the humidity conditioner.

[0009] 1 is a cross-sectional view schematically illustrating humidity conditioners of a first embodiment and a second embodiment; FIG. 2 is an image showing the change in transparency of the humidity conditioner of the first embodiment depending on the relative humidity of the air surrounding the humidity conditioner; FIG. 3 is a graph showing moisture absorption isotherms of sodium acetate, sodium propionate, and sodium formate at a temperature of 25°C; FIG. 4 is a graph showing moisture absorption isotherms of a moisture-absorbing component containing type B silica gel, a moisture-conditioning component containing lithium chloride and glycerin, and a moisture-conditioning component containing sodium formate as a main component; FIG. 5 is a graph showing moisture absorption isotherms of a moisture-conditioning component containing lithium chloride and glycerin, and a moisture-conditioning component containing sodium formate as a main component; FIG. 6 is a graph showing moisture absorption isotherms of a humidity conditioner containing a moisture-conditioning component consisting of sodium formate, and a humidity conditioner containing a moisture-conditioning component consisting of 1 part by weight of sodium formate and 1 part by weight of glycerin; FIG. 7 is a graph showing moisture absorption isotherms of a humidity conditioner containing a moisture-conditioning component consisting of sodium formate, and a moisture-conditioning component consisting of 2 parts by weight of sodium formate and 1 part by weight of glycerin. 1 is a graph showing moisture absorption isotherms of a humidity conditioner containing a humidity-conditioning component consisting of sodium formate, and a humidity conditioner containing a humidity-conditioning component consisting of 2 parts by weight of sodium formate and 1 part by weight of potassium formate. FIG. 2 is a diagram schematically illustrating a method for manufacturing a humidity conditioner of a first embodiment. FIG. 3 is a diagram schematically illustrating a method for manufacturing a humidity conditioner of a first embodiment. FIG. 4 is a diagram schematically illustrating a method for manufacturing a humidity conditioner of a first embodiment. FIG. 5 is a cross-sectional view schematically illustrating a daytime state of a transport container being transported from a hot and humid region to a cold region. FIG. 6 is a cross-sectional view schematically illustrating a nighttime state of a transport container being transported from a hot and humid region to a cold region. FIG. 7 is a plan view schematically illustrating a first alternative example of a water absorbent body provided in the humidity conditioner of the first embodiment. FIG. 8 is a perspective view schematically illustrating a second alternative example of a water absorbent body provided in the humidity conditioner of the first embodiment. FIG. 9 is a cross-sectional view schematically illustrating a third alternative example of a water absorbent body provided in the humidity conditioner of the first embodiment. Fig. 1 is a cross-sectional view schematically illustrating a fourth modified example of the water absorbent body provided in the humidity conditioner of the first embodiment. Fig. 2 is a cross-sectional view schematically illustrating a fifth modified example of the water absorbent body provided in the humidity conditioner of the first embodiment. Fig. 3 is a view illustrating a schematic example of a color change exhibited by the humidity conditioner of the second embodiment. Fig. 4 is a view for explaining the humidity conditioner of the third embodiment. Fig. 5 is a cross-sectional view schematically illustrating a humidity conditioner with packaging material of the fourth embodiment.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0011] 1. First Embodiment 1.1 Humidity Conditioning Material FIG. 1 is a cross-sectional view schematically illustrating a humidity conditioner of a first embodiment.

[0012] The humidity conditioner 1 of the first embodiment shown in FIG. 1 has a humidity-controlling ability to absorb moisture from the air surrounding the humidity conditioner 1 when the relative humidity of the air surrounding the humidity conditioner 1 is higher than the equilibrium humidity of the humidity conditioner 1, and to release moisture to the air surrounding the humidity conditioner 1 when the relative humidity of the air surrounding the humidity conditioner 1 is lower than the equilibrium humidity of the humidity conditioner 1. Compared to desiccants such as type A silica gel, the humidity conditioner 1 can desorb moisture by heating at a relatively low temperature. Furthermore, the humidity conditioner 1 can repeatedly absorb and release moisture. Therefore, the humidity conditioner 1 can, in principle, maintain its humidity-controlling ability semi-permanently. The equilibrium humidity of the humidity conditioner 1 can be adjusted by the materials constituting the humidity conditioner 1.

[0013] As shown in Fig. 1, the humidity conditioner 1 includes a water absorbent body 11 and a humidity control component 12. The water absorbent body 11 is made of a water absorbent material 21. The humidity control component 12 is present inside the water absorbent material 21. The humidity control component 12 absorbs or releases moisture. The humidity control component 12 includes a component that deliquesces.

[0014] The water absorbent body 11 and the water absorbent material 21 have a particulate shape. The water absorbent body 11 and the water absorbent material 21 have a diameter of, for example, several mm to several tens of mm.

[0015] The water absorbent material 21 can chemically or physically absorb the deliquescent component contained in the humidity-conditioning component 12. This can prevent the deliquescent component from leaving the water absorbent material 21 and causing water separation from the water absorbent material 21. When the humidity-conditioning component is a humidity-conditioning liquid, the water absorbent material 21 can be impregnated with the humidity-conditioning liquid. Desirably, 1 part by weight to 1,000 parts by weight of the humidity-conditioning liquid is impregnated into 100 parts by weight of the water absorbent material 21. By impregnating the water absorbent material 21 with the humidity-conditioning liquid, the interface area between the humidity-conditioning component and air can be increased compared to when the humidity-conditioning liquid is used alone. This can increase the humidity control rate.

[0016] The water absorbent material 21 contains at least one selected from the group consisting of water absorbent resins and clay minerals.

[0017] The water-absorbing resin may be an ionic resin or a non-ionic resin.

[0018] The ionic resin includes, for example, at least one selected from the group consisting of an alkali metal salt of polyacrylic acid and a starch-acrylate graft polymer. The alkali metal salt of polyacrylic acid includes, for example, sodium polyacrylate.

[0019] The nonionic resin includes, for example, at least one selected from the group consisting of vinyl acetate copolymer, maleic anhydride copolymer, polyvinyl alcohol, and polyalkylene oxide.

[0020] The clay mineral includes, for example, at least one selected from the group consisting of silicate minerals and zeolites. The silicate mineral includes, for example, at least one selected from the group consisting of sepiolite, attapulgite, kaolinite, perlite, and dolomite.

[0021] The humidity-conditioning component 12 includes a metal salt having a deliquescence point within a relative humidity range of 30% RH or more and 80% RH or less. The metal salt preferably forms a hydrate crystal within a relative humidity range of 30% RH or more and 80% RH or less. As a result, the humidity-conditioning component 12 has a threshold humidity within a relative humidity range of 30% RH or more and 80% RH or less, and is unable to absorb moisture when the relative humidity of the surrounding air is lower than the threshold humidity, but is able to absorb moisture when the relative humidity of the surrounding air is higher than the threshold humidity. The metal salt includes, for example, a carboxylate salt. The carboxylate salt includes, for example, at least one selected from the group consisting of sodium formate, sodium acetate, and sodium propionate.

[0022] The humidity-conditioning component 12 may contain a component other than the metal salt described above. For example, the humidity-conditioning component 12 may contain an additive for adjusting the threshold humidity described above. The additive may include, for example, at least one selected from the group consisting of a metal salt other than the metal salt described above, a polyhydric alcohol, and a nucleating material for hydrate crystals of the metal salt described above.

[0023] Examples of other metal salts include at least one of lithium chloride, calcium chloride, magnesium chloride, sodium benzoate, lithium bromide, calcium bromide, potassium bromide, sodium lactate, potassium lactate, potassium acetate, lithium acetate, potassium formate, sodium butyrate, sodium citrate, potassium citrate, sodium chloride, and potassium carbonate.

[0024] The polyhydric alcohol includes, for example, at least one selected from the group consisting of glycerin, propanediol, butanediol, pentanediol, trimethylolpropane, butanetriol, ethylene glycol, diethylene glycol, triethylene glycol, and lactic acid, and preferably includes a polyhydric alcohol having three or more hydroxyl groups. An example of a polyhydric alcohol having three or more hydroxyl groups is glycerin. The polyhydric alcohol may constitute a dimer or a polymer.

[0025] The nucleation material includes, for example, at least one selected from the group consisting of carboxylic acids having two or more carboxyl groups and amides having two or more amide groups.

[0026] A metal salt having a deliquescence point within a relative humidity range of 30% RH or higher and 80% RH or lower has a threshold humidity that forms the boundary between the relative humidity at which moisture absorption is substantially impossible and the relative humidity at which moisture absorption is substantially possible. The relative humidity at which moisture absorption is substantially impossible is a relative humidity that is lower than the threshold humidity including the relative humidity at which the metal salt forms a strong hydrate crystal with water molecules and / or the deliquescence point at which the metal salt deliquesces and liquefies. The relative humidity at which moisture absorption is substantially possible is a relative humidity that is higher than the threshold humidity. Furthermore, the humidity-conditioning component 12, due to the inclusion of the metal salt, has a threshold humidity that forms the boundary between the relative humidity at which moisture absorption is substantially impossible and the relative humidity at which moisture absorption is substantially possible. The additive is a substance that is hygroscopic and highly soluble in water, and changes the threshold humidity of the humidity-conditioning component 12 from the threshold humidity of the metal salt. Therefore, by including an appropriate additive in the humidity-conditioning component 12, a humidity-conditioning material 1 having a threshold humidity suitable for the intended use can be provided.

[0027] The content of the additive in the humidity-conditioning component 12 is preferably 10% by weight or more and 90% by weight or less. If the content is less than 10% by weight, it tends to be difficult to change the threshold humidity of the humidity-conditioning component 12 from the threshold humidity of the metal salt. If the content is more than 90% by weight, the threshold humidity that forms the boundary between the relative humidity at which moisture absorption cannot substantially occur and the relative humidity at which moisture absorption can substantially occur tends to become unclear.

[0028] FIG. 2 is an image showing the change in transparency of the humidity conditioner of the first embodiment depending on the relative humidity of the air around the humidity conditioner.

[0029] When the water absorbent 11 is transparent, as shown in FIG. 2 , the humidity conditioner 1 becomes opaque and non-transparent as humidity conditioner 1A when the relative humidity of the air surrounding the humidity conditioner 1 is lower than the threshold humidity of the humidity conditioner component 12 and the humidity conditioner component 12 is crystallized. On the other hand, when the relative humidity of the air surrounding the humidity conditioner 1 is higher than the threshold humidity of the humidity conditioner component 12 and the humidity conditioner component 12 is not crystallized, the humidity conditioner 1 becomes transparent as humidity conditioner 1B. Therefore, the humidity conditioner 1 can be used as a humidity indicator that indicates the relative humidity of the air surrounding the humidity conditioner 1. Furthermore, the threshold humidity of the humidity conditioner component 12 defines the boundary between the relative humidity at which the humidity conditioner 1 is transparent and the relative humidity at which the humidity conditioner 1 is not transparent. The additive can adjust the boundary between the relative humidity at which the humidity conditioner 1 is transparent and the relative humidity at which the humidity conditioner 1 is not transparent. Therefore, the additive can adjust the relative humidity indicated by the humidity conditioner 1.

[0030] 1.2 Threshold Humidity of Carboxylate Salts Figure 3 is a graph showing moisture absorption isotherms for sodium acetate, sodium propionate, and sodium formate. In the graph shown in Figure 3, the horizontal axis represents relative humidity, and the vertical axis represents moisture absorption rate.

[0031] Carboxylate salts, particularly sodium salts of carboxylic acids, hydrate to form strong hydrate crystals with water molecules. The strong hydrate crystals that form further hydrate and deliquesce to liquefy. However, a large amount of energy is required for the strong hydrate crystals that form to further hydrate. Therefore, when the relative humidity reaches a first relative humidity, the carboxylate salt hydrates to form strong hydrate crystals with water molecules, and when the relative humidity reaches a second relative humidity that is greater than the first relative humidity, the hydrate crystals deliquesce and liquefy. For example, as shown in FIG. 3, sodium acetate forms strong hydrate crystals with water molecules at a relative humidity of about 70% RH or less, and deliquesces and liquefies when the relative humidity reaches about 80% RH. The hydrate crystals are trihydrates. Furthermore, sodium propionate and sodium formate form strong hydrate crystals with water molecules at a relative humidity of about 50% RH or less, and the hydrate crystals deliquesce and liquefy when the relative humidity reaches about 60% RH.

[0032] For this reason, carboxylates, particularly sodium carboxylates, have a relative humidity at which they form strong hydrate crystals with water molecules and / or a threshold humidity that includes the deliquescence point at which they deliquesce and liquefy. Therefore, for carboxylates, particularly sodium carboxylates, when the relative humidity of the surrounding air is lower than the threshold humidity, moisture absorption does not proceed beyond the formation of hydrate crystals with water molecules, whereas when the relative humidity of the surrounding air is higher than the threshold humidity, moisture absorption proceeds rapidly and the moisture absorption rate increases. For example, as shown in Figure 3, for sodium acetate, when the relative humidity of the surrounding air is lower than approximately 70-80% RH, moisture absorption does not proceed beyond the formation of trihydrate, whereas when the relative humidity of the surrounding air is higher than approximately 70-80% RH, moisture absorption proceeds rapidly and the moisture absorption rate increases. Furthermore, in the case of sodium propionate and sodium formate, when the relative humidity of the surrounding air is lower than approximately 50 to 60% RH, moisture absorption does not proceed beyond the formation of hydrate crystals, whereas when the relative humidity of the surrounding air is higher than approximately 50 to 60% RH, moisture absorption proceeds rapidly and the moisture absorption rate increases.

[0033] For this reason, carboxylates have a threshold humidity that defines the boundary between the relative humidity at which moisture absorption hardly progresses and the relative humidity at which moisture absorption progresses rapidly. For example, as shown in Figure 3, sodium acetate has a threshold humidity of approximately 70 to 80% RH. Sodium propionate and sodium formate have threshold humidity of approximately 50 to 60% RH.

[0034] 4 is a graph showing moisture absorption isotherms for a moisture absorbing component containing type B silica gel, a moisture conditioning component containing lithium chloride and glycerin, and a moisture conditioning component containing sodium formate as a main component. In the graph shown in FIG. 4, the horizontal axis represents relative humidity, and the vertical axis represents moisture absorption rate.

[0035] The moisture absorption rates of moisture-absorbing components and humidity-conditioning components that do not have a threshold humidity gradually increase as the relative humidity increases. For example, as shown in FIG. 4, the moisture absorption rates of a moisture-absorbing component containing type B silica gel and a moisture-conditioning component containing lithium chloride and glycerin gradually increase as the relative humidity increases. In contrast, the moisture absorption rate of a humidity-conditioning component 12 that has a threshold humidity is small within a relative humidity range below the threshold humidity and rapidly increases as the relative humidity increases within a relative humidity range above the threshold humidity. For example, as shown in FIG. 4, the moisture absorption rate of a humidity-conditioning component 12 containing sodium formate as a main component is low enough that moisture absorption hardly progresses within a relative humidity range of approximately 0 to 50% RH, and rapidly increases as the relative humidity increases within a relative humidity range of approximately 50 to 90% RH. Therefore, a humidity-conditioning component 12 that has a threshold humidity has a threshold humidity that separates a relative humidity at which moisture absorption hardly progresses from a relative humidity at which moisture absorption rapidly progresses. For example, as shown in FIG. 4, a humidity-conditioning material containing sodium formate as a main component has a threshold humidity of approximately 50 to 60% RH, which distinguishes between a relative humidity at which moisture absorption hardly progresses and a relative humidity at which moisture absorption rapidly progresses.

[0036] Two or more types of carboxylates may be combined and included in the humidity-conditioning component 12. The additives described above may be included in the humidity-conditioning component 12 to affect the formation of hydrate crystals and adjust the threshold humidity and humidity-conditioning properties.

[0037] Due to the existence of the threshold humidity described above, the humidity-conditioning material 1 can be used in applications where it is important to have high humidity-conditioning ability in a specific humidity range. Furthermore, the humidity-conditioning material 1 can be dried and regenerated using low-temperature air having a relative humidity lower than the threshold humidity. That is, the humidity-conditioning material 1 does not require hot air heating during drying and regeneration. For example, when the humidity-conditioning component 12 contains sodium formate as a main component, the humidity-conditioning material 1 can be dried and regenerated using low-temperature air having a relative humidity lower than approximately 50-60% RH.

[0038] 1.3 Humidity Conditioning Effect Around the Threshold Humidity Figure 5 is a graph showing moisture absorption isotherms for a humidity conditioning component containing lithium chloride and glycerin, and a humidity conditioning component containing sodium formate as a main ingredient. In the graph shown in Figure 5, the horizontal axis represents relative humidity, and the vertical axis represents moisture absorption rate.

[0039] As described above, the moisture absorption rate of a humidity-conditioning component that does not have a threshold humidity gradually increases as the relative humidity increases. Therefore, the change in equilibrium humidity associated with the change in moisture absorption rate of the humidity-conditioning component, i.e., the change in the moisture content of the humidity-conditioning component, is large. For example, as shown in FIG. 5 , when the humidity-conditioning target humidity is 60% RH, when a humidity-conditioning component containing lithium chloride and glycerin releases 50% of its moisture-excluding weight, the regulated humidity shifts from 60% RH to 30% RH. In contrast, the moisture absorption rate of a humidity-conditioning component 12 that has a threshold humidity is low within a range of relative humidities below the threshold humidity and rapidly increases as the relative humidity increases within a range of relative humidities above the threshold humidity. Therefore, around the threshold humidity, the change in equilibrium humidity associated with the change in moisture absorption rate of the humidity-conditioning component 12, i.e., the change in the moisture content of the humidity-conditioning component 12, is small. For example, as shown in Figure 5, when the target humidity control humidity is 60% RH, when the humidity control component 12 containing sodium formate as the main component releases 50% of the weight of the humidity control material excluding water, the adjusted humidity only deviates from 60% RH to 55% RH.

[0040] Therefore, in the vicinity of the threshold humidity, the humidity-conditioning component 12 having the threshold humidity has a high humidity-conditioning effect and a large humidity-conditioning water content. Therefore, by adjusting the threshold humidity of the humidity-conditioning component 12 to the vicinity of the humidity-conditioning target humidity, the humidity-conditioning material 1 can condition the surrounding air so as to maintain the relative humidity of the surrounding air at a relative humidity close to the humidity-conditioning target humidity for a long period of time. 1.4 Adjustment of threshold humidity by additives

[0041] 6 is a graph showing moisture absorption isotherms for a humidity control material containing a humidity control component made of sodium formate and a humidity control material containing humidity control components made of 1 part by weight of sodium formate and 1 part by weight of glycerin, with the horizontal axis representing relative humidity and the vertical axis representing moisture absorption rate.

[0042] As shown in Figure 6, the threshold humidity of the humidity conditioner 1 containing the humidity-conditioning component 12 made of sodium formate is approximately 50% RH. In contrast, the threshold humidity of the humidity conditioner containing the humidity-conditioning component 12 made of 1 part by weight of sodium formate and 1 part by weight of glycerin is approximately 40% RH. Therefore, it can be seen from Figure 6 that glycerin is an additive that lowers the threshold humidity of the humidity conditioner 1 and the humidity-conditioning component 12 below that of sodium formate.

[0043] 7 is a graph showing moisture absorption isotherms for a humidity control material containing a humidity control component made of sodium formate and a humidity control material containing humidity control components made of 2 parts by weight of sodium formate and 1 part by weight of glycerin, with the horizontal axis representing relative humidity and the vertical axis representing moisture absorption rate.

[0044] As shown in Figure 7, the threshold humidity of the humidity conditioner 1 containing the humidity-conditioning component 12 made of sodium formate is approximately 50% RH. In contrast, the threshold humidity of the humidity conditioner containing the humidity-conditioning component 12 made of 2 parts by weight of sodium formate and 1 part by weight of glycerin is approximately 45% RH. Therefore, it can be seen from Figure 7 that glycerin is an additive that lowers the threshold humidity of the humidity conditioner 1 and the humidity-conditioning component 12 below that of sodium formate.

[0045] Furthermore, by comparing FIG. 6 with FIG. 7, it can be seen that the greater the content of glycerin as an additive, the greater the amount of decrease in the threshold humidity.

[0046] 8 is a graph showing moisture absorption isotherms for a humidity control material containing a humidity control component made of sodium formate and a humidity control material containing humidity control components made of 1 part by weight of sodium formate and 2 parts by weight of potassium formate. In the graph shown in FIG. 8, the horizontal axis represents relative humidity and the vertical axis represents moisture absorption rate.

[0047] As shown in Figure 8, the threshold humidity of the humidity conditioner 1 containing the humidity-conditioning component 12 made of sodium formate is approximately 50% RH. In contrast, the threshold humidity of the humidity conditioner containing the humidity-conditioning component 12 made of 1 part by weight of sodium formate and 2 parts by weight of potassium formate is approximately 45% RH. Therefore, it can be seen from Figure 8 that potassium formate is an additive that lowers the threshold humidity of the humidity conditioner 1 and the humidity-conditioning component 12 below that of sodium formate.

[0048] 1.5 Manufacturing Method of Humidity Conditioner FIGS. 9A, 9B, and 9C are diagrams for schematically explaining a manufacturing method of the humidity conditioner of the first embodiment.

[0049] In the manufacture of the humidity conditioner 1, a water absorbent body 11 is prepared as shown in FIG. 9A.

[0050] 9B , a humidity-conditioning liquid 31 is prepared. The prepared water absorbent body 11 is immersed in the prepared humidity-conditioning liquid 31. The water absorbent body 11 is kept immersed in the humidity-conditioning liquid 31 for, for example, several hours to one day. As a result, the humidity-conditioning liquid 31 permeates the water absorbent body 11, and the humidity-conditioning material 1 is formed. The permeated humidity-conditioning liquid 31 becomes the humidity-conditioning component 12 provided in the humidity-conditioning material 1.

[0051] 9C, the formed humidity conditioner 1 is pulled up from the remaining humidity conditioner liquid 31. The pulled-up humidity conditioner 1 has swelled, for example, 2 to 20 times its original size.

[0052] 1.6 Condensation Suppression Effect The humidity-conditioning material 1 has a high condensation suppression effect. Therefore, the humidity-conditioning material 1 is suitably used, for example, to suppress condensation that occurs inside a transport container that is transported from a hot and humid region to a cold region. Condensation is likely to occur when the cargo, packaging materials, etc. transported in the transport container contain a large amount of moisture.

[0053] 10A and 10B are cross-sectional views of a shipping container being transported from a hot and humid region to a cold region during the day and at night, respectively.

[0054] Consider a case where the temperature is 33°C and the relative humidity is 38% RH during the day as shown in Figure 10A, and the temperature is 4°C and the relative humidity is greater than 90% RH at night as shown in Figure 10B.

[0055] When the air temperature rises during the daytime, the temperature inside the transport container 41 also rises. For example, as shown in Figure 10A, the temperature of the ceiling surface 51 becomes 33°C, the temperature of the middle air 52 becomes 26°C, and the temperature of the lower air 53 becomes 19°C. As a result, moisture evaporates from the cargo, packaging materials, wooden pallets, etc. contained in the transport container 41, and moisture evaporates from the floor surface, etc. that make up the transport container 41. This increases the absolute humidity inside the transport container 41.

[0056] As time passes and the air temperature drops at night, radiation from the ceiling surface 51 and wall surfaces 54 of the transport container 41 lowers the temperatures of the ceiling surface 51 and wall surfaces 54. This reduces the amount of saturated water vapor in the air near the ceiling surface 51 and wall surfaces 54. This causes the absolute humidity inside the transport container 41 to become higher than the amount of saturated water vapor in the air near the ceiling surface 51 and wall surfaces 54. This causes condensation to form on the ceiling surface 51 and wall surfaces 54.

[0057] The temperature fluctuations inside the transport container 41 increase as one approaches the ceiling surface 51. For example, the temperature difference between day and night on the ceiling surface 51 is 29°C, the temperature difference between day and night on the middle air 52 is 19°C, and the temperature difference between day and night on the lower air 53 is 10°C.

[0058] When a humidity-conditioning material 1 having a humidity-conditioning component 12 containing sodium formate as a main ingredient and having the moisture absorption isotherm shown in Figure 4 is placed inside a transport container 41, the humidity-conditioning material 1 absorbs moisture at night when the relative humidity is higher than the threshold humidity, thereby preventing condensation from occurring, and releases moisture during the day when the relative humidity is lower than the threshold humidity, thereby regenerating to a dry state. This makes it possible to prevent condensation from occurring and to regenerate the humidity-conditioning material 1 without heating it with a heater. In other words, a cycle of moisture absorption and regeneration occurs through the daily temperature cycle, allowing condensation to be suppressed over the long term.

[0059] In order to efficiently cycle the moisture absorption and regeneration according to the daily temperature cycle, the threshold humidity of the humidity-controlling component 12 is adjusted so that it is higher than the daytime relative humidity, thereby achieving a high dew condensation suppression effect.

[0060] 1.7 Metal Corrosion Inhibition Table 1 shows the relative metal corrosion rates of chloride-free CMA, acetate compounds, and sodium formate, and chloride-containing sodium chloride, calcium chloride, magnesium chloride, and acetate compounds. CMA is calcium magnesium acetate. Chloride-containing acetate compounds are mixtures of chloride-free acetate compounds and sodium chloride.

[0061]

[0062] It can be seen from Table 1 that the metal corrosion amounts of CMA, acetate compounds, and sodium formate, which do not contain chloride, are significantly smaller than the metal corrosion amounts of sodium chloride, calcium chloride, magnesium chloride, and acetate compounds, which contain chloride.

[0063] Furthermore, it can be seen from Table 1 that the metal corrosion amount of acetic acid compounds containing chloride is smaller than the metal corrosion amount of sodium chloride, calcium chloride, and magnesium chloride which also contain chloride.

[0064] From these facts, it can be understood that the amount of metal corrosion of the humidity-conditioning component 12 whose main component is a carboxylate such as CMA, an acetic acid compound, or sodium formate is smaller than the amount of metal corrosion of the humidity-conditioning component whose main component is a chloride.

[0065] Therefore, the humidity-conditioning material 1 including the humidity-conditioning component 12 containing a carboxylate as a main component is less likely to cause rust on metals, etc., and can be used in many applications. For example, the humidity-conditioning material 1 can be used for humidity-conditioning storage of various luxury items containing metals, such as musical instruments and cameras, and for suppressing condensation inside electrical boxes and transport containers.

[0066] 1.8 Other Examples of Water Absorbent Body FIG. 11 is a plan view schematically illustrating a first other example of the water absorbent body provided in the humidity conditioner of the first embodiment.

[0067] The water absorbent body 11 shown in Fig. 11 has a powdery shape and has a diameter of, for example, several micrometers to several millimeters.

[0068] FIG. 12 is a perspective view that schematically illustrates a second alternative example of the water absorbent body provided in the humidity conditioner of the first embodiment.

[0069] The water absorbent body 11 shown in FIG. 12 has a sheet-like shape.

[0070] FIG. 13 is a cross-sectional view schematically illustrating a third alternative example of the water absorbent body provided in the humidity conditioner of the first embodiment.

[0071] The water absorbent body 11 shown in Fig. 13 includes a water absorbent material 21 and a support 22. In the water absorbent body 11 shown in Fig. 13, the water absorbent material 21 has a powdery or granular shape. The support 22 is a porous body. The porous body is a foam. The water absorbent material 21 is supported by the support 22. When the porous body constituting the support 22 is a foam, the support 22 has high rigidity. This allows the humidity conditioner 1 to have a stable shape. The support 22 may be impregnated with a humidity-conditioning liquid.

[0072] FIG. 14 is a cross-sectional view schematically illustrating a fourth alternative example of the water absorbent body provided in the humidity conditioner of the first embodiment.

[0073] The water absorbent body 11 shown in FIG. 14 includes a water absorbent material 21 and a support 22. In the water absorbent body 11 shown in FIG. 14, the water absorbent material 21 is in a powdery or granular form. The support 22 is a porous body. The porous body is a nonwoven fabric or a woven fabric. The water absorbent material 21 is supported by the support 22. When the porous body constituting the support 22 is a nonwoven fabric or a woven fabric, the support 22 has flexibility. Therefore, the support 22 can be deformed. The support 22 may be impregnated with a humidity-conditioning liquid.

[0074] FIG. 15 is a cross-sectional view schematically illustrating a fifth alternative example of the water absorbent body provided in the humidity conditioner of the first embodiment.

[0075] The water absorbent body 11 shown in FIG. 15 includes a water-absorbent material 21 and a support 22. In the water absorbent body 11 shown in FIG. 15, the water-absorbent material 21 is in a powdery or granular form. The support 22 is a ventilation member that allows airflow to pass through in a direction perpendicular to the cross section shown in FIG. 15. The ventilation member includes, for example, a corrugated nonwoven fabric. The water-absorbent material 21 is supported by the support 22. With the water absorbent body 11 shown in FIG. 15, by passing airflow through the ventilation member, the water-absorbent material 21 supported on the ventilation member can be efficiently brought into contact with air, allowing the water-absorbent material 21 to efficiently absorb moisture and release moisture. The water absorbent body 11 shown in FIG. 15 may be incorporated into a rotating body. The support 22 may be impregnated with a humidity-conditioning liquid.

[0076] 2 Second Embodiment The following describes the differences between the second embodiment and the first embodiment. For points that are not described, the second embodiment also employs the same configuration as that employed in the first embodiment.

[0077] Fig. 1 is also a cross-sectional view that schematically illustrates the humidity conditioner of the second embodiment. Fig. 16 is a diagram that schematically illustrates an example of a color change exhibited by the humidity conditioner of the second embodiment.

[0078] 16, the humidity-conditioning material 2 of the second embodiment includes an indicator 23. The indicator 23 exhibits a color that changes depending on the moisture content of the humidity-conditioning component 12. This allows the humidity-conditioning material 2 to have an indicating function of displaying the conditioned humidity by color.

[0079] The indicator 23 includes, for example, a pH indicator. A pH indicator can be used as the indicator 23 because the pH of the humidity-conditioning component 12 changes depending on the moisture content of the humidity-conditioning component 12.

[0080] The pH indicator is, for example, at least one selected from the group consisting of bromocresol green, methyl orange, methyl red, methyl purple, methylene blue, bromocresol purple, bromothymol blue, bromophenol blue, chlorophenol red, neutral red, phenol red, cresol red, curcumin, phenolphthalein, α-naphtholphthalein, thymolphthalein, and alizarin yellow.

[0081] The humidity conditioner 2 may contain two or more types of pH indicators. The two or more types of pH indicators are preferably pH indicators that change color at different pH values. This increases the variety of color changes exhibited by the humidity conditioner 2 in response to changes in pH. This allows the conditioned humidity to be checked more precisely.

[0082] In the example shown in Figure 16, indicator 23 indicates that when the relative humidity falls below the range of 40 to 60% RH, the color of the humidity-regulating material 2 changes to purple, and when the relative humidity rises above the range of 40 to 60% RH, the color of the humidity-regulating material 2 changes from green to transparent.

[0083] 3 Third Embodiment The following describes the differences between the third embodiment and the first embodiment. For points that are not described, the third embodiment also employs the same configuration as that employed in the first embodiment.

[0084] FIG. 17 is a diagram illustrating a humidity conditioner according to the third embodiment.

[0085] 17 includes a fragrance 24. The fragrance 24 is contained within the water-absorbent material 21.

[0086] When the relative humidity is lower than the threshold humidity, the carboxylate is crystallized and the fragrance 24 is trapped inside the carboxylate crystals, which prevents the fragrance 24 from evaporating from the humidity conditioner 3 and prevents the fragrance from being released from the humidity conditioner 3.

[0087] When the relative humidity is higher than the threshold humidity, the crystal structure of the carboxylate dissolves, and the fragrance 24 is released from the carboxylate. As a result, the fragrance 24 evaporates from the humidity conditioner 3, and the fragrance is released from the humidity conditioner 3.

[0088] These features allow the humidity conditioner 3 to have the function of an aromatic agent that triggers the release of fragrance in response to changes in humidity.

[0089] Examples of fragrances include acetyl isoeugenol, acetyl eugenol, acetyl cedrene, acetophenone, anise alcohol, anisaldehyde, anethole, allyl amyl glycolate, allyl ionone, methyl anthranilate, benzyl benzoate, ionone, indole, eugenol, n-octanal, calone, camphor, benzyl cinnamate, geraniol, cedryl acetate, cinnamyl acetate, tricyclodecenyl acetate, phenylethyl acetate, o-t-butylcyclohexyl acetate, p-t-butylcyclohexyl acetate, acetic acid Benzyl, amyl salicylate, cyclohexyl salicylate, sandalmysole core (2-methyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-2-buten-1-ol)), cis-3-hexenol, citral, citronellol, methyl dihydrojasmonate, dihydromyrcenol, terpineol, damascone, thymol, decanal, δ-decalactone, γ-decalactone decyl aldehyde, terpineol, terpinene, n-nonanal, γ-nonalactone, methyl 2-nonenoate, bacdanol , pinene, phenylethyl alcohol, allyl phenoxyacetate, 1-(2-t-butylcyclohexyloxy)-2-butanol, flutate (ethyl tricyclo[5.2.1.02,6]decan-2-ylcarboxylate), styrallyl propionate, benzyl propionate, n-hexanal, allyl hexanoate, α-hexyl cinnamic aldehyde, allyl heptanoate, heliotropin, benzyl alcohol, benzaldehyde, borneol, myrac aldehyde (4-(4-methyl-3-pentenyl)-3-cyclohexyl) The composition contains at least one selected from the group consisting of ethylhexyl 2,4-dimethyl-3-cyclohexen-1-carboxaldehyde), 4-methyl-3-decen-5-ol, ethyl 3-methyl-3-phenylglycidate, 3-methyl-5-phenylpentanol, ethyl 2-methylbutyrate, lime oxide, ethyl butyrate, ligustral (2,4-dimethyl-3-cyclohexenylcarboxaldehyde), linalool, limonene, styrax oil, tonka bean, pine oil, petitgrain oil, pepper oil, peppermint oil, and rosemary oil.

[0090] 4 Fourth Embodiment FIG. 18 is a cross-sectional view that schematically illustrates a humidity conditioner with a packaging material according to a fourth embodiment.

[0091] The packaging-attached humidity conditioner 5 shown in FIG. 18 includes a humidity conditioner 61 and a packaging material 62 .

[0092] The humidity control material 61 is the humidity control material 1, 2 or 3 described above.

[0093] The packaging material 62 has moisture permeability and packages the humidity conditioner 61 .

[0094] This makes it possible to prevent the humidity control material 61 from coming into direct contact with the humidity control target, and also makes it possible for the humidity control material 61 to control the humidity of the humidity control target.

[0095] The packaging material 62 is a soft case that is flexible and has a bag-like shape. The packaging material 62 may be a packaging material other than a soft case. The packaging material other than a soft case is, for example, a box.

[0096] The packaging material 62 includes a moisture-permeable membrane 71 and a light-transmitting film 72. The moisture-permeable membrane 71 has moisture permeability. The moisture-permeable membrane 71 is, for example, a polyester nonwoven fabric. The light-transmitting film 72 has light transparency. The light-transmitting film 72 is, for example, a polyethylene terephthalate film. The light-transmitting film 72 allows the state of the humidity conditioner 61 to be visually observed. In particular, when the humidity conditioner 61 is a humidity conditioner 2 having an indicating function, the color exhibited by the indicating function can be visually observed through the light-transmitting film 72.

[0097] The packaging material 62 includes a surface material 81 and a back surface material 82. In the fourth embodiment, the surface material 81 is a light-transmitting film 72, and the back surface material 82 is a moisture-permeable film 71. Only a portion of the surface material 81 may be the light-transmitting film 72. The edges of the surface material 81 and the edges of the back surface material 82 are welded by heat sealing.

[0098] The present disclosure is not limited to the above-described embodiments, and may be replaced with a configuration that is substantially the same as the configuration shown in the above-described embodiments, a configuration that has the same effect, or a configuration that can achieve the same purpose.

Claims

1. A water absorbent body including a water absorbent material; A moisture-regulating component that is present in the water-absorbent material and absorbs or releases moisture; Equipped with The humidity control component contains a metal salt having a deliquescence point within a relative humidity range of 30% RH or more and 80% RH or less. Moisture regulating material.

2. The water-absorbing material includes at least one selected from the group consisting of water-absorbing resins and clay minerals. The humidity conditioner according to claim 1.

3. The water-absorbent resin contains sodium polyacrylate. The humidity conditioner according to claim 2.

4. The water absorbent body is provided with a carrier that supports the water absorbent material. The humidity conditioner according to claim 1.

5. The water absorbent has a granular, powdery or sheet-like shape. The humidity conditioner according to claim 1.

6. The metal salt forms hydrate crystals within a relative humidity range of 30% RH or more and 80% RH or less. The humidity conditioner according to claim 1.

7. The metal salt includes a carboxylate. The humidity conditioner according to claim 1.

8. The metal salt includes at least one selected from the group consisting of sodium formate, sodium acetate, and sodium propionate. The humidity conditioner according to claim 1.

9. The metal salt has a threshold humidity that forms a boundary between a relative humidity at which moisture absorption cannot be substantially performed and a relative humidity at which moisture absorption can be substantially performed, The moisture-conditioning component has a threshold humidity that forms a boundary between a relative humidity at which moisture absorption cannot be substantially performed and a relative humidity at which moisture absorption can be substantially performed, The humidity control component includes an additive that changes the threshold humidity of the humidity control component from the threshold humidity of the metal salt. The humidity conditioner according to claim 1.

10. The additive comprises at least one selected from the group consisting of a metal salt other than the metal salt, a polyhydric alcohol, and a nucleating material for a hydrate crystal of the metal salt. The humidity conditioner according to claim 9.

11. The other metal salt includes at least one of lithium chloride, calcium chloride, magnesium chloride, sodium benzoate, lithium bromide, calcium bromide, potassium bromide, sodium lactate, potassium lactate, potassium acetate, lithium acetate, potassium formate, sodium butyrate, sodium citrate, potassium citrate, sodium chloride, and potassium carbonate. The humidity conditioner according to claim 10.

12. The polyhydric alcohol includes at least one selected from the group consisting of glycerin, propanediol, butanediol, pentanediol, trimethylolpropane, butanetriol, ethylene glycol, diethylene glycol, triethylene glycol, and lactic acid. The humidity conditioner according to claim 10.

13. The nucleation material includes at least one selected from the group consisting of carboxylic acids having two or more carboxyl groups and amides having two or more amide groups. The humidity conditioner according to claim 10.

14. The content of the additive in the humidity control component is 10% by mass or more and 90% by mass or less. The humidity conditioner according to claim 9.

15. The support is a porous body. The humidity conditioner according to claim 4.

16. The porous body is a foam, a nonwoven fabric, or a woven fabric. The humidity conditioner according to claim 15.

17. The moisture-conditioning component is provided with an indicator that exhibits a color that changes depending on the moisture content of the moisture-conditioning component. The humidity conditioner according to claim 1.

18. The indicator comprises a pH indicator. The humidity conditioner according to claim 17.

19. The water-absorbing material includes a fragrance. The humidity conditioner according to claim 1.

20. The humidity control material according to claim 1, A packaging material having moisture permeability and packaging the humidity conditioner; A humidity-regulating material with packaging material.