Humidity control composition, humidity control member, and humidity control device

Abstract

One aspect of the present disclosure provides a humidity control composition that is highly safe and capable of significantly reducing the occurrence of corrosiveness and unpleasant odor in a metal while maintaining humidity control performance. A humidity control composition according to one aspect of the present disclosure is characterized by comprising: a humidity control component of a deliquescent salt that forms a hydrate crystal at a prescribed critical relative humidity; and a water absorption material having high water absorption properties with respect to an electrolyte aqueous solution.

Description

Humidity-conditioning composition, humidity-conditioning member, and humidity-conditioning device

[0001] This application claims priority to Japanese Patent Application No. 2024-022479, filed February 19, 2024, the contents of which are incorporated herein by reference.

[0002] Humidity-conditioning compositions have been disclosed in the past.

[0003] For example, Patent Document 1 discloses a humidity-conditioning composition that contains at least one of sodium acetate and potassium acetate and a water-absorbent binder, and the ratio (Ac:B) of the total amount of sodium acetate and potassium acetate (Ac) to the amount of water-absorbent binder (B) is in the range of 2:3 to 4:1 by mass, in order to provide a moisture-absorbing composition that is inexpensive, has high moisture absorption properties, and is highly safe with little risk of metal rust or the like.

[0004] JP 2012-245489 A

[0005] However, the humidity-conditioning composition described in Patent Document 1 uses only sodium acetate in the humidity-conditioning composition, and sodium acetate is also corrosive, so there is a risk of corrosion.

[0006] In view of the above problems, one aspect of the present disclosure aims to provide a highly safe humidity-conditioning composition that can significantly reduce corrosiveness to metals and the generation of unpleasant odors while maintaining humidity-conditioning performance.

[0007] A humidity-conditioning composition according to one embodiment of the present disclosure is characterized by comprising a humidity-conditioning component that is a deliquescent salt that forms hydrate crystals at a predetermined critical relative humidity, and a water-absorbing material that has a high degree of water absorption capacity for an aqueous electrolyte solution.

[0008] A humidity control member according to another aspect of the present disclosure is characterized by comprising the humidity control composition described above and a support substrate carrying the humidity control composition.

[0009] A humidity control device according to another aspect of the present disclosure includes the humidity control member described above and a blower that blows air to the humidity control member.

[0010] As described above, according to one aspect of the present disclosure, by comprising a humidity-controlling component that is a deliquescent salt that forms hydrate crystals at a predetermined critical relative humidity, and a water-absorbing material that has a high degree of water absorption for an aqueous electrolyte solution, it is possible to provide a highly safe humidity-controlling composition that can suppress the release of carboxylic acids that volatilize into the environment while maintaining humidity-controlling performance, and can significantly reduce corrosiveness to metals and the generation of unpleasant odors.

[0011] FIG. 1 is a cross-sectional view schematically showing a humidity-conditioning composition according to the present disclosure. FIG. 2 is an adsorption isotherm for a humidity-conditioning component. FIG. 3 is a perspective view schematically showing a humidity-conditioning member according to the present disclosure. FIG. 4 is a perspective view schematically showing a humidity-conditioning member according to the present disclosure. FIG. 5 is a front view of a support substrate. FIG. 6 is a front view of a modified support substrate. FIG. 7 is a front view of a modified support substrate. FIG. 8 is a front view of a modified support substrate. FIG. 9 is a perspective view of a modified support substrate. FIG. 10 is a perspective view of a modified support substrate. FIG. 11 is a front view of a modified support substrate. FIG. 12 is a cross-sectional view schematically showing a humidity control device according to the present disclosure.

[0012] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present disclosure described in the claims, and not all of the configurations described in the embodiments are necessarily essential to the solutions of the present disclosure. Note that in the drawings, the X axis represents the air flow direction, the Y axis represents the width direction, and the Z axis represents the height direction.

[0013] [Humidity-conditioning composition] Fig. 1 is a cross-sectional view schematically showing a humidity-conditioning composition 10 according to the present disclosure. As shown in Fig. 1, the humidity-conditioning composition 10 according to the present disclosure comprises a humidity-conditioning component 11 and a water-absorbing material 12. The humidity-conditioning component 11 is impregnated into the water-absorbing material 12.

[0014] The humidity-conditioning component 11 is a deliquescent salt that forms a hydrate crystal at a predetermined critical relative humidity. The humidity-conditioning component 11 absorbs and releases humidity in the air, thereby achieving a large humidity control capacity.

[0015] The humidity-conditioning component 11 may be present inside the water-absorbing material 12 or may be present outside the water-absorbing material 12 .

[0016] Here, "humidity control" means adjusting the relative humidity of the air in the surrounding environment so that it approaches the equilibrium humidity of the humidity control component 11. Specifically, for example, if the equilibrium humidity of the humidity control component 11 is 50% RH, the humidity control component 11 absorbs moisture (moisture absorption) when the relative humidity of the air in the surrounding environment is higher than 50% RH, and releases moisture (moisture release) when the relative humidity of the air in the surrounding environment is lower than 50% RH.

[0017] FIG. 2 shows the adsorption isotherm for the humidity-conditioning component 11. As shown in FIG. 2, sodium acetate, sodium propionate, and sodium formate are carboxylates that form hydrate crystals and promote rapid moisture absorption and desorption at a predetermined relative humidity or higher. The relative humidity at which such a change occurs is called the critical relative humidity. The critical relative humidity for sodium acetate, sodium propionate, and sodium formate exists in the relative humidity range of 50% to 90%. For sodium acetate, sodium propionate, and sodium formate, the moisture absorption amount per unit weight of the humidity-conditioning component 11 increases by approximately 0 to 400% in a specific humidity range of 50% to 90%, which includes the predetermined critical relative humidity. Therefore, when used in an ambient environment with a relative humidity of 50% to 90%, the absolute amount of moisture absorbed or released is large, resulting in high humidity-conditioning functionality.

[0018]

[0019] Table 1 shows the moisture absorption amount per unit weight of the humidity-conditioning component at 50% RH and 90% RH, and the difference in moisture absorption amount between 90% RH and 50% RH.

[0020] Sodium formate, sodium acetate, and sodium propionate have critical relative humidity ranges of 50% to 80% RH. Potassium acetate and potassium formate do not have critical relative humidity, but maintain a high moisture absorption capacity from low to high relative humidity. Compared to silica gel B, a common moisture absorbent, they are expected to have a large moisture conditioning capacity in the humidity range of medium relative humidity or higher. For example, when comparing the moisture conditioning capacity of sodium formate, sodium acetate, sodium propionate, potassium acetate, and potassium formate by measuring the difference between the moisture absorption capacity at 90% RH and the moisture absorption capacity at 50% RH, they have a moisture conditioning capacity that is approximately 5 to 10 times that of silica gel B.

[0021] Therefore, the humidity-controlling component 11 is a carboxylate. Furthermore, the humidity-controlling component 11 is preferably at least one selected from the group consisting of sodium formate, sodium acetate, and sodium propionate. The critical relative humidity is approximately 50% for sodium formate and sodium propionate, and approximately 70% for sodium acetate. Since the absolute amount of moisture absorbed or released is large when controlling humidity in an ambient environment that includes the critical relative humidity, the humidity-controlling component 11 has a high humidity-controlling function. For example, the comfortable humidity range in a living environment is 40% to 70%, and a large humidity control capacity can be expected within this humidity range.

[0022] Assuming that the humidity-conditioning component 11 contains a carboxylate, other components may be added as additives for adjusting the critical relative humidity. Specific examples of such components include polydeliquescent substances, polyhydric alcohols, and nucleating materials for hydrate crystals. Specific examples of nucleating materials include carboxylic acids having two or more carboxyl groups and amides having two or more amide groups.

[0023] Deliquescent substances are classified into salts and water-soluble organic substances. Specific examples of salts include potassium formate, ammonium formate, potassium acetate, lithium acetate, ammonium acetate, sodium lactate, potassium lactate, sodium benzoate, potassium benzoate, potassium propionate, calcium chloride, lithium chloride, magnesium chloride, calcium chloride, lithium chloride, potassium chloride, zinc chloride, aluminum chloride, lithium bromide, calcium bromide, potassium bromide, sodium hydroxide, sodium pyrrolidonecarboxylate, potassium carbonate, calcium citrate, sodium citrate, potassium citrate, and lithium citrate. Only one of these salts may be contained, or two or more may be contained. Specific examples of water-soluble organic substances include sugars such as sucrose, pullulan, glucose, xylose, fructose, mannitol, and sorbitol, carboxylic acids such as citric acid, and amides such as urea.

[0024] Specific examples of polyhydric alcohols include glycerin, propanediol, butanediol, pentanediol, trimethylolpropane, butanetriol, ethylene glycol, diethylene glycol, and triethylene glycol. Among these, polyhydric alcohols having three or more hydroxyl groups, such as glycerin, are more preferred. The polyhydric alcohol may form a dimer or polymer. The polyhydric alcohol may contain only one of the above materials, or two or more of them.

[0025] Specific examples of the nucleating material include carboxylic acids having two or more carboxyl groups, and amides having two or more amide groups.

[0026] Table 2 shows the characteristics of formic acid, acetic acid, and propionic acid liberated from sodium formate, sodium acetate, and sodium propionate.

[0027]

[0028] The acid dissociation constants, vapor pressures, olfactory thresholds, and metal corrosivity of formic acid, acetic acid, and propionic acid are shown in Table 2.

[0029] The acid dissociation constant is a quantitative indicator of the strength of an acid (how easily hydrogen ions dissociate). The lower the value, the stronger the acid. The order of ease of dissociation is propionic acid, followed by acetic acid and formic acid.

[0030] Vapor pressure is the pressure of a gas when the liquid and gas are in equilibrium, and the higher the vapor pressure, the easier it is to volatilize. The order of ease of volatilization is formic acid, acetic acid, and propionic acid. In other words, sodium propionate is easily liberated, but propionic acid is significantly less volatile than the other two carboxylic acids, so it is predicted to have the lowest concentration of volatilization into the environment.

[0031] The olfactory threshold values ​​are zero for formic acid, 0.006 ppm for acetic acid, and 0.0057 ppm for propionic acid. When acetic acid and propionic acid are liberated from the humidity-conditioning composition 10 and volatilize into the environment, exceeding the olfactory threshold concentration, it is predicted that the odor will be perceived as an unpleasant odor. Therefore, the pH of the humidity-conditioning composition 10 can be maintained alkaline by the water-absorbing material 12 described below, which suppresses the liberation of carboxylic acids and the concentration of carboxylic acids volatilizing into the environment, thereby significantly reducing the generation of unpleasant odors.

[0032] Metal corrosivity is described in the literature "Copper corrosion occurring in an environment of formic acid, acetic acid, and propionic acid" (Zairyou-to-Kankyo 64, 452-457 (2015)). Among formic acid, acetic acid, and propionic acid, propionic acid is the least corrosive.

[0033] The humidity-conditioning composition 10 according to the present disclosure includes a water-absorbing material 12. The humidity-conditioning composition 10 can maintain and improve its humidity-conditioning performance (absorption and release performance) by including the water-absorbing material 12 in addition to the humidity-conditioning component 11. Therefore, the water-absorbing material 12 has a high degree of water-absorbing ability for an aqueous electrolyte solution.

[0034] The water-absorbing material 12 has the function of retaining the humidity-conditioning component 11. Because the water-absorbing material 12 retains the humidity-conditioning component 11, the humidity-conditioning composition 10 can be realized with a high surface area-to-volume ratio. Therefore, the humidity-conditioning composition 10 can increase the rate of moisture absorption or release. As described above, the water-absorbing material 12 can maintain the pH of the humidity-conditioning composition 10 closer to alkaline. Selecting a salt-resistant resin as the water-absorbing material 12 maintains the pH more alkaline than selecting sodium polyacrylate, a water-absorbing resin, as the water-absorbing material 12, thereby reducing odor. The humidity-conditioning composition 10 according to the present disclosure can simultaneously increase the humidity-conditioning amount and reduce the risk of odor generation and metal corrosion.

[0035] In addition, the water-absorbing material 12 contains an aqueous solution of the humidity-regulating component 11, thereby increasing the amount of component carried; the increased surface area increases the response speed of moisture absorption or release; the water-absorbing material 12 itself is hygroscopic; the viscosity of the water-absorbing material 12 itself increases the applicability of the mixed solution of the humidity-regulating component 11 and the water-absorbing material 12, thereby increasing the amount of component carried on the support substrate.

[0036] Here, when a high concentration of deliquescent carboxylate salt is mixed with an ionic water-absorbent resin in the presence of water, the carboxylic acid is liberated, and there is a concern that the volatilized carboxylic acid may cause odor or rust if the carboxylic acid adheres to metals. While the liberation of carboxylic acid can be suppressed by adding only a pH adjuster to the humidity-conditioning component 11 to maintain a neutral to alkaline state, the pH adjuster becomes localized in the humidity-conditioning component 11, resulting in an unstable effect. Furthermore, when the pH adjuster is an electrolyte, the total amount of the humidity-conditioning component 11 contained in the water-absorbent resin is reduced, resulting in a decrease in humidity-conditioning performance.

[0037] Therefore, the humidity-conditioning composition 10 comprises a humidity-conditioning component 11, which is a deliquescent salt that forms hydrate crystals at a predetermined critical relative humidity, and a water-absorbing material 12 that has high water absorption properties for aqueous electrolyte solutions, thereby suppressing pH fluctuations, inhibiting the release of carboxylic acids, and significantly reducing corrosiveness to metals and the generation of unpleasant odors. Furthermore, the moisture-absorbing properties of the composition have a critical relative humidity in the range of approximately 50% to 90%, and the composition rapidly absorbs moisture in high-humidity environments above the critical relative humidity and rapidly releases moisture in low-humidity environments below the critical relative humidity, thereby increasing the humidity-conditioning moisture content.

[0038] The water absorbent material 12 is preferably a water absorbent resin capable of absorbing a high-concentration electrolyte solution and maintaining an alkaline pH. The water absorbent material 12 also preferably contains a nonionic water absorbent resin that has a high absorption capacity for a high-concentration electrolyte solution.

[0039] Furthermore, from the viewpoint that a water-absorbing resin capable of maintaining an alkaline pH is preferable, the water-absorbing material 12 preferably contains an ionic water-absorbing resin having a sulfonic acid group.

[0040] Specific examples of the ionic resin include copolymer crosslinked products of monomers consisting of sulfoalkyl (meth)acrylate monomers, (meth)acrylic acid monomers, and, if necessary, other polymerizable monomers.

[0041] Specific examples of nonionic resins include vinyl acetate copolymers, maleic anhydride copolymers, polyvinyl alcohol, and polyalkylene oxides.

[0042] The water absorbent material 12 may also be a clay mineral. Examples of clay minerals include silicate minerals such as sepiolite, attapulgite, kaolinite perlite, and dolomite, and zeolites.

[0043] The humidity conditioning capacity of the humidity-conditioning composition 10 is determined by the concentration of the humidity-conditioning component 11 and the water absorption capacity (encapsulation capacity) of the water-absorbing material 12. To maximize this, the weight ratio of the humidity-conditioning component 11 to the water-absorbing material 12 is adjusted. Therefore, the ratio of the water-absorbing material 12 to the humidity-conditioning component 11 is preferably in the range of 1:1 to 1:6 by mass. The viscosity of the coating liquid of the humidity-conditioning composition 10 is specified within a selected range so that it can be applied. If the humidity-conditioning component 11 is too high, the risk of syneresis increases in high humidity ranges, while if the humidity-conditioning component 11 is too low, the humidity-conditioning capacity may decrease.

[0044] Ionic and non-ionic resins will now be described in more detail.

[0045] The swelling principle of ionic resins is due to the affinity between the absorbent resin, which is a polymer electrolyte, and the solution, the osmotic pressure generated because the mobile ion concentration is higher inside the gel than in the solution outside the absorbent resin, and the ionic repulsive force of the electrolyte structure inside the absorbent resin.

[0046] Ionic resins have a structural characteristic of having an electrolyte structure such as a carboxyl group. These characteristics include high gel strength, a high absorption capacity for pure water, and a low absorption capacity for electrolyte solutions. Specific examples of these substances include crosslinked acrylic acid (salt) polymers, hydrolyzates of starch-acrylonitrile graft copolymers, neutralized starch-acrylic acid graft copolymers, and saponified acrylic acid ester-vinyl acetate copolymers.

[0047] Ionic resins preferably have a structural feature that includes sulfonic acid groups, which are strong electrolytes. These features include a high absorption rate for electrolyte solutions containing polyvalent ions due to the large negative charge of the sulfonic acid groups, a low absorption rate for electrolyte solutions containing monovalent ions, and high cost. Specific examples of such materials include copolymer crosslinked products of monomers consisting of sulfoalkyl (meth)acrylate monomers, (meth)acrylic acid monomers, and, if necessary, other polymerizable monomers.

[0048] Ionic resins are cross-linked electrolyte polymers with ionic groups. Examples of their compositions include sodium acrylate, sodium acrylate polymer, polyacrylate, and vinyl alcohol-acrylate copolymers. There are many different types depending on the type of polymer, cross-linking method, and manufacturing method. Even resins with the same composition can have significantly different properties depending on the degree of cross-linking, ionizable group density, and manufacturing method.

[0049] Sodium polyacrylate has a large number of hydrophilic carboxyl groups and exhibits high water retention. Crosslinking during polymerization forms a resin with a network structure. When the resin becomes wet, the electrostatic repulsion between the negatively charged carboxylate ions causes the network to expand, allowing water to penetrate the network structure within the resin and causing the resin to swell. The finer the network, the greater the water retention capacity. Furthermore, the hydrogen ions in the carboxyl groups are replaced by sodium ions, increasing water absorption. If the sodium ion concentration in the gel is higher than that of the solvent outside the gel, osmotic pressure is generated to eliminate the difference in sodium ion concentration, causing the solvent to penetrate the gel. When the solvent, water, penetrates the gel due to the effect of osmotic pressure, the gel's water retention progresses.

[0050] Introducing sulfonic acid groups into an ionic water-absorbing resin results in an ionic water-absorbing resin having sulfonic acid groups. A water-absorbing resin of sodium polyacrylate having sulfonic acid groups is an example of an ionic water-absorbing resin having sulfonic acid groups. Because sulfonic acid groups are dissociable groups with large negative charges, water-absorbing resins having sulfonic acid groups effectively exhibit hydrophilicity and water-absorbing properties even in solutions containing polyvalent metal ions.

[0051] The swelling principle of nonionic resins is that they swell due to the functional groups in their structure and their affinity.

[0052] Nonionic resins have a structural characteristic of having hydrophilic segments, which are characterized by low gel strength, slow water absorption rate, and low absolute value of water absorption capacity. Specific examples of such substances include cross-linked polyvinyl alcohol modified products and partially cross-linked cross-linked polyethylene oxide products.

[0053] [Humidity Control Member] Fig. 3 is a perspective view schematically showing a humidity control member 100 according to the present disclosure. As shown in Fig. 3, the humidity control member 100 according to the present disclosure includes the humidity control composition 10 described above and a support substrate 20 supporting the humidity control composition 10.

[0054] The support substrate 20 supports the humidity-conditioning composition 10. The humidity-conditioning composition 10 is supported by adhering it to the surface of the support substrate 20.

[0055] The humidity-conditioning member 100 can have humidity-conditioning performance by supporting the humidity-conditioning composition 10 on a support substrate 20. For example, as shown in Fig. 3, by blowing air in the X direction, the air flows through the support substrate 20 supporting the humidity-conditioning composition 10, and the air absorbs moisture from the air or releases moisture into the air, thereby performing humidity control.

[0056] The support substrate 20 may be in the form of a rectangular pillar as shown in FIG. 3 or a cylinder as shown in FIG.

[0057] The support substrate 20 is preferably a member made of resin, ceramic, or metal, which allows efficient heat exchange in addition to moisture exchange by the humidity-conditioning composition 10. Furthermore, the support substrate 20 has a structure in which at least a portion thereof is breathable.

[0058] The support substrate 20 may be a heat storage substrate or a nonwoven fabric.

[0059] Fig. 5 is a front view of the support substrate 20 included in the humidity control member 100 according to the present disclosure. Figs. 6 to 11 are front views of modified examples of the support substrate 20.

[0060] The support substrate 20 may be triangular as shown in Fig. 5, corrugated as shown in Fig. 6, honeycomb as shown in Fig. 7, or rectangular as shown in Fig. 8. The support substrate 20 may also have a pleated or corrugated structure. This increases the surface area of ​​the breathable substrate, allowing it to come into efficient contact with circulating air, further improving moisture absorption and desorption efficiency.

[0061] The support substrate 20 may also have a hollow column shape. By using such a hollow column shape, a large amount of the humidity-conditioning component 11 can be supported, and therefore the moisture absorption amount can be increased.

[0062] Furthermore, the support substrate 20 may have a fin shape as shown in Figures 9 and 10. The support substrate 20 shown in Figure 9 has a structure in which several protrusions (pin fins) are provided on a single plate. The support substrate 20 shown in Figure 10 has a structure in which several plates are provided perpendicular to a single plate, and has a fin structure.

[0063] In addition, the support substrate 20 can also have a structure in which a single plate is wavy, a structure in which a single plate is provided with perforated fins, a structure in which convex portions are provided above and below a single plate and are offset, a structure in which a single plate is bent in a wavy shape to form convex portions that are then continuously formed into a U-shape, a structure in which small corrugations are further formed on the surface of the convex portion, a structure in which perforations are provided on the side of the convex portion, a structure in which perforations are provided on the surface and side of the convex portion, etc.

[0064] The support substrate 20 may also have a sponge metal structure. Sponge metal is made of metal with many voids like a sponge. Because the sponge metal structure has many voids, it can efficiently exchange both moisture and heat.

[0065] Furthermore, the support substrate 20 may have a structure formed by overlapping a corrugated plate and a flat plate and rolling them, as shown in Fig. 11. Such a structure increases the surface area, enabling more efficient moisture and heat exchange.

[0066] The average particle size of the water-absorbing material 12 is preferably 5 to 100 μm, more preferably 10 to 50 μm. Selecting a water-absorbing material 12 within this particle size range increases the specific surface area, thereby improving the moisture absorption or release response rate of the humidity-conditioning composition 10 and improving moisture exchange efficiency. Furthermore, when the humidity-conditioning composition 10 is prepared as a coating solution and applied to the support substrate 20, selecting a water-absorbing material 12 within this particle size range allows the viscosity of the water-absorbing material 12 to be adjusted to a coatable level, allowing the composition to be supported without the need for a separate binder. This prevents the surface of the water-absorbing material 12 from being coated with a binder, resulting in a decrease in air contact efficiency, enabling efficient moisture exchange by the humidity-conditioning composition 10. The average particle size is measured in a dry state, and the average particle size calculated by measuring the particle size of several tens of randomly selected water-absorbing resin particles using image analysis is used as the average particle size.

[0067] 12 is a cross-sectional view schematically illustrating a humidity control device 1000 according to the present disclosure. The humidity control device 1000 according to the present disclosure includes the humidity control member 100 described above, an air blower 30 that blows air to the humidity control member 100, and a pipe 40 that houses them.

[0068] The blower 30 is composed of a fan, a motor, etc. The blower 30 blows air, for example, in one direction to the humidity control member 100. In this way, the relative humidity of the outflowing air can be controlled by absorbing or releasing moisture depending on the relative humidity of the circulating air. For example, if the incoming air has a higher humidity than the equilibrium humidity of the humidity control member 11, the humidity control member 100 can provide dry air by absorbing moisture. If the incoming air has a lower humidity than the equilibrium humidity of the humidity control member 11, the humidity control member 100 can provide humid air by releasing moisture.

[0069] The air blower 30 blows air to the humidity control member 100 in two directions, for example by reversing the rotation direction of the fan. Assuming a summer environment where one side is indoors and the other is outdoors, moisture is absorbed from the high-humidity air flowing in from outdoors, providing low-humidity air indoors. When the air blowing direction is reversed, moisture is released from the humidity control member 11 by the low-humidity air inside the room, and high-humidity air is exhausted outdoors. This allows humidity-controlled air to be continuously provided indoors, enabling ventilation that suppresses fluctuations in the relative humidity inside the room. If the support substrate 20 has heat storage properties, heat exchange can be performed simultaneously with the exchange of moisture in the air.

[0070] The tube 40 is not limited as long as it can accommodate the humidity control member 100 and the blower device 30. The tube 40 is preferably made of metal to improve heat exchange efficiency.

[0071] Examples of the humidity control device 1000 according to the present disclosure include a time-division total heat exchange ventilation device in which the airflow direction changes over time, a dehumidifier, a dryer, a dishwasher-dryer, and the like.

[0072] The humidity-conditioning composition and humidity-conditioning member according to the present disclosure will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the examples described here.

[0073] (Example 1) Based on a deliquescent concentration of 16% at 90% relative humidity, the mixing ratio of the water-absorbing material to the humidity-conditioning component was set in the range of 1:1 to 1:6 by mass so as to achieve a viscosity of 100 to 500 cP that can be applied to a support substrate.

[0074] Sodium propionate was used as the humidity control component, and salt-resistant resin was used as the water absorbent.

[0075] A mixture of a moisture-conditioning component and a water-absorbing material was supported on a ceramic honeycomb support substrate.

[0076] (Example 2) A nonionic resin was used as the water absorbent material, and the other conditions were the same as those of Example 1.

[0077] (Example 3) The same conditions as in Example 1 were used except that sodium formate was used as the humidity-regulating component.

[0078] (Example 4) A nonionic resin was used as the water absorbent material, and the other conditions were the same as those of Example 3.

[0079] (Example 5) The support substrate was assumed to be a sheet made of nonwoven fabric. Based on a deliquescent concentration of 12% at 90% relative humidity, the mixing ratio of the water-absorbing material to the humidity-conditioning component was set to a range of 1:1 to 1:6 by mass to achieve a viscosity of 5 to 100 cP, which is the target for application to the support substrate. Potassium acetate was used as the humidity-conditioning component. A salt-resistant resin was also used as the water-absorbing material.

[0080] Example 6 The same conditions as in Example 5 were used except that potassium formate was used as the humidity-regulating component.

[0081] Comparative Example 1 Sodium propionate was used as the humidity-conditioning component, and no water-absorbing material was used. The other conditions were the same as those of Example 1.

[0082] Comparative Example 2 The same conditions as in Comparative Example 1 were used except that sodium formate was used as the humidity-controlling component.

[0083] Comparative Example 3: Potassium acetate was used as the humidity-conditioning component. An ionic water-absorbing resin was used as the water-absorbing material. The other conditions were the same as those of Example 5.

[0084] Comparative Example 4: Potassium acetate was used as the humidity-conditioning component. No water-absorbing material was used. The other conditions were the same as those of Example 5.

[0085] Comparative Example 5 The same conditions as in Example 5 were used except that potassium formate was used as the humidity-conditioning component and an ionic water-absorbing resin was used as the water-absorbing material.

[0086] Comparative Example 6: Potassium formate was used as the humidity-conditioning component. No water-absorbing material was used. The other conditions were the same as those of Example 5.

[0087] Reference Example 1 Sodium propionate was used as the humidity-conditioning component, and an ionic resin made of sodium polyacrylate was used as the water-absorbing material.

[0088] (Reference Example 2) The same conditions as in Reference Example 1 were used except that sodium formate was used as the humidity-conditioning component.

[0089] The salt-resistant resin used in Examples 1, 3, 5, and 6 is an ionic water-absorbing resin made of sodium polyacrylate having sulfonic acid groups, specifically a cross-linked copolymer of sulfoalkyl acrylate and acrylic acid. A certain proportion of the sodium carboxylate and carboxylic acid in cross-linked sodium polyacrylate are sulfoalkylated to form —COO—(CH ２ ) ｍ -SO ３ The structure of H introduces a sulfonic acid group into the copolymer.

[0090] Cross-linked sodium polyacrylate is a polymer formed by copolymerizing a cross-linking monomer during the polymerization of acrylic acid and acrylic acid salts, resulting in a cross-linked network structure. Water penetrates into the network structure formed by the cross-linking, allowing the polymer to absorb water. Because the cross-linked polymers are covalently bonded together, they do not dissolve even when they absorb water. Polyacrylates, which are generally used as superabsorbent resins, have a cross-linked structure. Sulfoalkyl acrylate-acrylic acid copolymer cross-linked products are materials that have improved initial absorption rates for highly concentrated electrolyte solutions by introducing sulfonic acid groups into cross-linked sodium polyacrylate, a water-absorbing resin.

[0091] The nonionic resin used in Examples 2 and 4 is a polyalkylene oxide-based water-absorbing resin. The nonionic resin absorbs water by bonding with water molecules through hydrogen bonds between the hydrophilic groups of the nonionic resin, but does not bond with metal ions.

[0092] The ionic resin used in Comparative Example 3, Comparative Example 5, Reference Example 1, and Reference Example 2 is an ionic water-absorbing resin, which is a crosslinked polymer of acrylic acid and an acrylic acid salt, specifically crosslinked sodium polyacrylate. The ratio of acrylic acid to sodium acrylate is not limited. The higher the ratio of acrylic acid, the more acidic the resin becomes.

[0093] The above conditions and results are shown in Table 3. The normalized loading amount is a value used to compare the amount of humidity-controlling component loaded by the ceramic honeycomb per volume between Examples and Comparative Examples, and was normalized based on the loading amount when no water-absorbing material was used in Comparative Example 1 or Comparative Example 2. The larger the value, the more humidity-controlling component is loaded on the loading substrate. Comparative Example 1 did not use a water-absorbing material, so the value is "1," while Examples using a water-absorbing material were 1.8 or 2.0, indicating that the presence of a water-absorbing material allows the loading substrate to have a larger amount of humidity-controlling component.

[0094]

[0095] As shown in Table 3, the humidity-conditioning compositions (Examples 1 to 4) comprising a humidity-conditioning component and a water-absorbent material maintained humidity-conditioning performance while suppressing pH fluctuations and carboxylic acid release, significantly reducing metal corrosivity and the generation of unpleasant odors. Furthermore, in the humidity-conditioning compositions of Examples 1 to 4, the pH was 6-7 when an ionic water-absorbent resin was added to the water-absorbent resin, while the pH was 7-8 when a salt-resistant resin and a nonionic resin were added to the water-absorbent resin. The pH shifted more toward alkaline when a salt-resistant resin and a nonionic resin were added to the water-absorbent resin, significantly reducing metal corrosivity and the generation of unpleasant odors. Furthermore, the humidity-conditioning compositions of Examples 1 to 4 were capable of excellent moisture absorption and release, and exhibited high humidity-conditioning performance.

[0096] On the other hand, Comparative Example 1, which did not include a water-absorbing material, had insufficient humidity-conditioning performance. Also, Comparative Example 2, which did not include a water-absorbing material, had insufficient humidity-conditioning performance. On the other hand, Reference Example 1, in which an ionic resin was added to the water-absorbing material, had poor fluidity of the mixed solution (coating liquid) of the humidity-conditioning component and the water-absorbing material, making it difficult to apply to the support substrate, and also had insufficient humidity-conditioning performance.

[0097] When potassium acetate was used as the humidity-conditioning component, the presence or absence of acetic acid was judged by the smell of the coating impregnation liquid. Formic acid liberated from potassium formate has a weak odor, so the presence or absence of volatilization cannot be judged by the odor. Since it is clear that for each water-absorbing material, a tendency for pH to change with acid liberation occurs similar to that of potassium acetate, the presence or absence of acid liberation was judged by pH alone. The fact that the pH does not fluctuate toward the acidic side and there is little liberation of carboxylic acid means that metal corrosivity is low.

[0098] In Comparative Example 4, which did not include a water-absorbing material, an odor of acetic acid was emitted. In addition, the amount of the humidity-conditioning component retained in the substrate depends solely on the water-absorbing property of the substrate, and since the amount supported was insufficient, the humidity-conditioning performance was insufficient.

[0099] In Examples 5 and 6, which contained a water-absorbing resin, the amount of moisture-conditioning component carried was improved compared to Comparative Examples 4 and 6, which did not use a water-absorbing material, and they had high moisture-conditioning performance. In Comparative Example 3, which used an ionic resin as a water-absorbing material, an odor of acetic acid was confirmed. In both Comparative Examples 3 and 5, which contained an ionic resin, a shift in pH to the acidic side was confirmed, and it was also confirmed that acid was being released from the pH.

[0100] In Example 5, in which a salt-resistant resin was used as the water absorbent material, no acetic acid odor was detected and pH fluctuations were also suppressed, confirming that no acetic acid liberation occurred. pH fluctuations were also suppressed in Example 6. In Examples 5 and 6, in which a salt-resistant resin was used, no acid liberation was detected, and corrosiveness to metals and the generation of unpleasant odors could be reduced.

[0101] As described above, the humidity-controlling composition, humidity-controlling member, and humidity-controlling device according to the present disclosure can suppress the liberation of carboxylic acids that volatilize into the environment while maintaining humidity-controlling performance, thereby significantly reducing corrosiveness to metals and the generation of unpleasant odors.

[0102] Although each embodiment and each example of the present disclosure have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure.

[0103] For example, a term that is described at least once in the specification or drawings together with a different term having a broader or equivalent meaning can be replaced with that different term anywhere in the specification or drawings. Furthermore, the configurations and operations of the humidity-conditioning composition, humidity-conditioning member, and humidity-conditioning device are not limited to those described in the embodiments and examples of the present disclosure, and various modifications are possible.

Claims

1. A humidity-conditioning composition comprising: a humidity-conditioning component that is a deliquescent salt that forms hydrate crystals at a predetermined critical relative humidity; and a water-absorbing material that has a high degree of water-absorbency for an aqueous electrolyte solution.

2. The humidity-conditioning composition according to claim 1, wherein the humidity-conditioning component is a carboxylate.

3. The humidity-conditioning composition according to claim 1, wherein the humidity-conditioning component is at least one selected from the group consisting of sodium formate, sodium acetate, sodium propionate, potassium acetate, and potassium formate.

4. The humidity-conditioning composition according to claim 1, wherein the humidity-conditioning component includes an additive that adjusts the critical relative humidity.

5. The humidity-conditioning composition according to claim 1, wherein the water-absorbing material contains an ionic water-absorbing resin having sulfonic acid groups.

6. The humidity-conditioning composition according to claim 1, wherein the water-absorbing material contains an ionic water-absorbing resin made of sodium polyacrylate having sulfonic acid groups.

7. The humidity-conditioning composition according to claim 1, wherein the water-absorbing material contains a nonionic water-absorbing resin.

8. A humidity-conditioning member comprising: the humidity-conditioning composition according to any one of claims 1 to 7; and a support substrate carrying the humidity-conditioning composition.

9. The humidity control member according to claim 8, wherein the support substrate is a member made of resin, ceramic, or metal, and at least a portion of the support substrate has a structure that allows air to pass through.

10. The humidity control member according to claim 8, wherein the average particle size of the water-absorbing material is 5 to 100 μm.

11. A humidity control device comprising: the humidity control member according to claim 8; and a blower that blows air to the humidity control member.

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