Humidity-conditioning member

Abstract

The purpose of an embodiment of the present disclosure is to provide a humidity-conditioning member which has a high humidity-conditioning function and has rigidity. This humidity-conditioning member is characterized by comprising at least two bases and, interposed between the bases, a humidity-conditioning layer comprising a humidity-conditioning material that absorbs or releases water vapor. The humidity-conditioning member is further characterized in that the bases have air permeability. comprise high-melting-point fibers and a first low-melting-point component that is heat-fusible, and include portions in which the high-melting-point fibers have been fused to each other via the first low-melting-point component due to the melting of at least the first low-melting-point component.

Description

Humidity control materials

[0001] This application claims priority to Japanese Patent Application No. 2024-014515, filed on February 2, 2024, the contents of which are incorporated herein by reference.

[0002] Humidity control members have been disclosed in the past.

[0003] For example, Patent Document 1 discloses a humidity-conditioning sheet 10 having a humidity-conditioning layer 7 between two base sheets 1 and 2, which is formed by bonding humidity-conditioning particles 3 that reversibly absorb and release water vapor together with a thermoplastic resin powder 4 and forming them into a sheet. Patent Document 1 also discloses that, because a large proportion of voids 8 are formed between the humidity-conditioning particles 3, 3, the voids 8 between the humidity-conditioning particles 3, 3 are utilized as water-retaining spaces for moisture absorption and release, and by utilizing not only the moisture absorption and release capacity of the humidity-conditioning particles themselves but also the moisture absorption and release capacity of the voids between the humidity-conditioning particles, high reversible moisture absorption and release performance and excellent moisture absorption and release responsiveness can be obtained.

[0004] JP 2008-174730 A

[0005] However, conventional humidity-conditioning sheets generally use a nonwoven or woven fabric substrate made of physically intertwined resin fibers, resulting in flexibility and low rigidity due to the material of the fibers that make them up. Therefore, for use as interior or wall materials for humidity control in homes, offices, containers, truck compartments, storage sheds, etc., rigidity is required, making them difficult to use alone and requiring their use in combination with other board materials. Furthermore, conventional humidity-conditioning sheets lack rigidity and are therefore easily deformed, making it difficult to maintain a specific shape. In particular, when intended for use as an automotive interior component, they must be conformed to the desired shape, so they are attached to a molded component for use. As described above, for applications requiring a certain level of rigidity or a specific three-dimensional shape, humidity-conditioning sheets cannot be constructed alone; even if attached to another component, the humidity-conditioning sheet's low rigidity is exposed on the surface, making them unsuitable for practical use. Patent Document 1 cites examples of nonwoven or woven fabrics as substrate sheets, but does not describe the fibers that make them up. It is assumed that the substrate sheet is a conventional nonwoven or woven fabric, which could potentially present the same issues as the humidity-conditioning sheets described above.

[0006] In view of the above problems, one aspect of the present disclosure aims to provide a humidity control member that has high humidity control function and rigidity.

[0007] A humidity-conditioning member according to one aspect of the present disclosure comprises at least two substrates and a humidity-conditioning layer between the substrates, the humidity-conditioning layer including a humidity-conditioning body that absorbs or releases water vapor, the substrates being breathable and including a first low-melting-point component that can be heat-fused to high-melting-point fibers, and including a portion where the high-melting-point fibers are fused together via the first low-melting-point component by melting at least the first low-melting-point component.

[0008] As described above, according to one aspect of the present disclosure, it is possible to provide a humidity control member that has high humidity control function and rigidity.

[0009] FIG. 1 is a cross-sectional view schematically showing a humidity-conditioning member according to the present disclosure, showing that the first low-melting point component contained in the substrate is particulate. FIG. 2 is a schematic view of a substrate, showing that the first low-melting point component contained in the substrate is particulate. FIG. 3 is a cross-sectional view schematically showing a humidity-conditioning member according to the present disclosure, showing that the second low-melting point component contained in the humidity-conditioning layer is fibrous. FIG. 4 is a schematic view of a substrate, showing that the first low-melting point component contained in the substrate is fibrous. FIG. 5 is a schematic view of a substrate, showing that the first low-melting point component contained in the substrate is present on at least a portion of the periphery of the high-melting point fiber. FIG. 6 is an enlarged view of portion VI in FIG. 5. FIG. 7 is a schematic view of a substrate, showing that a high-melting point skeletal fiber is mixed in addition to the first low-melting point component present on the periphery of the high-melting point fiber. FIG. 8 is a cross-sectional view schematically showing a humidity conditioner. FIG. 9 is a cross-sectional view schematically showing a humidity-conditioning member according to the present disclosure, showing a simplified manufacturing method. Fig. 10 is a diagram showing how a humidity control member according to the present disclosure is molded using a mold. Fig. 11 is a diagram showing a humidity control member according to the present disclosure in a box shape. Fig. 12 is a diagram showing a humidity control member in which a moisture-impermeable layer is provided on one of two substrates on the side opposite to the side in contact with the humidity control layer. Fig. 13 is a diagram of the humidity control member shown in Fig. 12 after being molded using a mold. Fig. 14 is a diagram showing the moisture absorption rates in Examples and Comparative Examples.

[0010] 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 as means for solving the problems of the present disclosure.

[0011] Fig. 1 is a cross-sectional view schematically illustrating a humidity control member 100 according to the present disclosure, and Fig. 2 is a schematic diagram of a substrate 10. As shown in Fig. 1, the humidity control member 100 according to the present disclosure includes at least two substrates 10, with a humidity control layer 23 between the substrates 10. As shown in Figs. 1 and 2, the substrate 10 includes a first low-melting-point component 31 that is heat-fusible with the high-melting-point fibers 11, and includes regions 311 where the high-melting-point fibers 11 are fused together via the first low-melting-point component 31 upon melting of the first low-melting-point component 31. In this way, after melting, the first low-melting-point component 31 fuses and fixes the high-melting-point fibers 11 together, resulting in a higher rigidity and less deformation than conventional nonwoven fabric materials.

[0012] The humidity-conditioning layer 23 also includes a humidity-conditioning element 20 that absorbs or releases water vapor. Furthermore, the substrate 10 is breathable, and water vapor can pass through the substrate 10 like an air flow 200, thereby conditioning the humidity of the air outside the humidity-conditioning member 100. With this configuration, it is possible to obtain a humidity-conditioning member 100 that has high rigidity, yet is capable of conditioning the humidity of the outside air, and is molded into a desired shape.

[0013] FIG. 3 is a cross-sectional view schematically illustrating another embodiment of a humidity control member 100 according to the present disclosure. As shown in FIG. 3, the humidity control layer 23 includes a second low-melting-point component 32 having a melting point lower than that of the first low-melting-point component 31. The second low-melting-point component 32 fuses the humidity control elements 20 together, the humidity control elements 20 and the substrate 10, or the substrates 10 together. This strengthens the bonding strength of the entire humidity control element 100, increases the peel strength of the substrate 10, and prevents the humidity control elements 20 from falling off the edge of the substrate 10. Furthermore, the humidity control layer 23 also has rigidity, further improving the rigidity of the humidity control element 100.

[0014] When the humidity control member 100 is manufactured by hot pressing, as described below, there is a possibility that the humidity control body 20 or the second low-melting-point component 32 may partially enter the interior of the substrate 10. In this case, the humidity control member 100 may have a mixed layer containing the humidity control body 20 or the second low-melting-point component 32 between the substrate 10 and the humidity control layer 23.

[0015] In Figure 1, the humidity-conditioning member 100 is composed of two substrates 10 and one humidity-conditioning layer 23, but the number of substrates 10 and humidity-conditioning layers 23 that form the humidity-conditioning member 100 is not limited, and the humidity-conditioning member 100 may be composed of two or more substrates 10 and one humidity-conditioning layer 23 less than the number of substrates 10.

[0016] According to this embodiment, the humidity control member 100 can be made thicker and more rigid, and can be more easily molded into a desired shape.

[0017] Examples of the high melting point fibers 11 include high melting point polyesters and plant fibers. The melting point of the high melting point fibers 11 is preferably 200° C. or higher.

[0018] The high melting point polyester is not particularly limited, but examples thereof include those having fiber-forming ability, particularly aromatic polyesters and semi-aromatic polyesters that are used as fibers.

[0019] Specific examples include polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polytrimethylene terephthalate, and copolymer polyesters having these as basic skeletons.

[0020] Other examples include polyethylene terephthalate, polyethylene isophthalate, polytetramethylene terephthalate, polyethylene oxybenzoate, polybutylene terephthalate, polyhexamethylene terephthalate, poly 1,4-dimethylcyclohexane terephthalate, polypivalolactone, and copolyesters containing these components.

[0021] The plant fiber is not particularly limited, but examples thereof include rayon, cellulose fiber, Manila hemp, sisal hemp, softwood kraft pulp (NBKP), hardwood kraft pulp (LBKP), linter, kenaf, mitsumata, kozo, gampi, and other wood pulps.

[0022] As explained above, the substrate 10 includes the heat-fusible first low-melting component 31 in addition to the high-melting fiber 11. The first low-melting component 31 is a heat-fusible thermoplastic component. The melting point of the first low-melting component 31 is preferably about 90 to 180°C.

[0023] The first low melting point component 31 may include polyester-based materials such as polyester, polyethylene, polypropylene, polyurethane, polyhydroxybutyrate, polylactic acid, polybutylene succinate, and copolymer materials thereof.

[0024] The polyester-based material is not particularly limited, but aliphatic polyesters such as polyhydroxybutyrate, polybutylene succinate, polylactic acid, polycaprolactone, and polyglycolic acid, and copolymers thereof are preferred.

[0025] The composition ratio of the high-melting-point fibers 11 and the first low-melting-point component 31 is preferably 20 to 60% by weight, and more preferably 30 to 50% by weight, of the first low-melting-point component 31 relative to the total weight of the high-melting-point fibers 11 and the first low-melting-point component 31. If the low-melting-point component is more than 60% by weight, the breathability of the humidity control member 100 may be significantly reduced. If the low-melting-point component is less than 20% by weight, the number of fused portions may be reduced, making it difficult to increase rigidity and the shape may not be maintained during heat pressing.

[0026] The first low-melting point component 31 may be fibrous in shape, as shown in Fig. 4. The fibrous shape allows the first low-melting point component 31 to be entangled with the high-melting point fibers 11, thereby increasing the number of contact points between the first low-melting point component 31 and the high-melting point fibers 11. This allows the first low-melting point component 31 to be efficiently fused with low energy when the substrate 10 is heat-pressed.

[0027] The first low-melting point component 31 may also be in particulate form. FIGS. 1 and 2 illustrate the case where the first low-melting point component 31 is in particulate form. Because it is in particulate form, it can be dispersed on the substrate 10 and can be widely dispersed on the substrate 10, thereby suppressing in-plane variations in the areas where the high-melting point fibers 11 are fused. Furthermore, the material options for the first low-melting point component 31 can be broader than with a fibrous component. Even if the first low-melting point component 31 is in particulate form, the mixing ratio with the fibrous high-melting point fibers 11 can be freely designed, thereby increasing the design freedom for rigidity and breathability.

[0028] FIG. 5 is a schematic diagram of the substrate 10, showing that the first low-melting-point component 31 contained in the substrate 10 is present on at least a portion of the periphery of the high-melting-point fiber 11. FIG. 6 is an enlarged view of portion VI in FIG. 5. As shown in FIGS. 5 and 6, the first low-melting-point component 31 may be present on at least a portion of the periphery of the high-melting-point fiber 11. Alternatively, the high-melting-point fiber 11 may have a core-sheath structure coated with the first low-melting-point component 31. The high-melting-point fiber 11 may form the core, and the first low-melting-point component 31 may form the sheath. In this manner, the low-melting-point component 31 is more uniformly dispersed within the substrate 10, increasing the uniformity of voids after heat pressing, thereby reducing the locational imbalance in the breathability and humidity-conditioning function of the humidity control member 100. Furthermore, because the first low-melting-point component 31 is present at the contact points of the high-melting-point fiber 11, it is efficiently fused, thereby increasing the rigidity of the humidity control member 100.

[0029] 7 is a schematic diagram of the substrate 10, showing the separately mixed skeletal fiber 12. The first low-melting point component 31 may be present at least partially on the periphery of the high-melting point fiber 11, and the substrate may further include a separate skeletal fiber 12. In this way, the rigidity of the humidity control member 100 can be easily adjusted by adjusting the blending ratio of the high-melting point fiber 11 to the skeletal fiber 12.

[0030] Furthermore, the rigidity of the humidity control member 100 according to the present disclosure is preferably 500 MPa or more in terms of bending rigidity. By setting the rigidity to 500 MPa or more, the humidity control member 100 can retain its shape and can be molded into a desired shape.

[0031] Next, the humidity control element 20 will be described.

[0032] The humidity control element 20 has a high humidity control function by absorbing or releasing water vapor. Each component of the humidity control element 20 will be described below.

[0033] The humidity conditioner 20 includes a water absorbent 21 containing a resin and / or a clay mineral, and a humidity-conditioning component 22. The water absorbent 21 of the humidity conditioner 20 can retain the humidity-conditioning component 22. The humidity conditioner 20 also regulates the amount of water vapor contained in the air. The humidity conditioner 20 has the property of absorbing (moisture-absorbing) water vapor when the surrounding relative humidity is relatively high relative to the equilibrium humidity of the humidity conditioner 20, and conversely, releasing (moisture-releasing) water vapor when the surrounding relative humidity is relatively low; this function is referred to as "humidity control." Specifically, for example, if the equilibrium humidity of the humidity conditioner 20 is 50% RH, the humidity conditioner 20 absorbs (moisture-absorbing) water vapor when the relative humidity of the surrounding air is higher than 50% RH, and releases (moisture-releasing) water vapor when the relative humidity of the surrounding air is lower than 50% RH. Typically, the equilibrium humidity of the humidity conditioner 20 correlates with the material of the humidity conditioner 20 and the moisture content of the humidity-conditioning component 22. This humidity-conditioning function allows the humidity conditioner 20 to regulate the amount of water vapor in the air surrounding the humidity-conditioning member 100 via the breathable substrate 10, thereby suppressing fluctuations in relative humidity. That is, unlike desiccants such as typical type A silica gel, the humidity conditioner 20 spontaneously releases moisture when in a low-humidity environment, eliminating the need for artificial regeneration, such as heating, and repeatedly absorbs and releases moisture as the environment changes daily, making it essentially effective for a semi-permanent period of time. Furthermore, when used in a sealed space where the amount of moisture held by the humidity conditioner 20 is overwhelmingly greater than the amount of water vapor in the sealed space, the relative humidity of the sealed space can be adjusted and maintained at approximately the same as the equilibrium humidity of the humidity conditioner 20.

[0034] As shown in FIG. 8 , the humidity conditioner 20 is preferably particulate. Being particulate increases the contact area per volume with air flowing in from outside the humidity control member 100, thereby increasing the rate of moisture absorption and desorption. Furthermore, when forming the humidity control layer 23, the humidity control member 20 can be sprayed onto the substrate 10, reducing variations in the humidity control performance of the humidity control member 100. Adjusting the amount sprayed allows for adjustment of humidity control performance, increasing design flexibility. Furthermore, if the substrate 10 is porous, the particle diameter of the humidity control member 20 is larger than the pores of the substrate 10. This prevents the humidity control member 20 from falling off the substrate 10. Furthermore, the particle diameter of the humidity control member 20 is preferably 50 to 1000 μm. If the particle diameter is less than 50 μm, the particle diameter is smaller than the pores between fibers in a typical nonwoven fabric, and there is a risk of the humidity control member 20 falling off the substrate 10. Furthermore, if the thickness is 1000 μm or more, the surface area per volume becomes large, making it difficult to increase the rate of moisture absorption and desorption. The humidity conditioner 20 absorbs and absorbs water vapor contained in the air in accordance with the humidity of the environment in which it is placed, or releases moisture contained in the humidity conditioner 20 into the air and desorbs moisture. By providing the water absorber 21, even if the humidity-conditioning component 22 excessively absorbs water vapor from the air, the water absorber 21 can retain moisture, thereby preventing leakage of moisture or an aqueous solution containing the humidity-conditioning component 22 from the humidity-conditioning member 100. Furthermore, when the humidity conditioner 20 is composed of the water absorber 21 and the humidity-conditioning component 22, it is preferable that the melting points of the respective components be higher than the melting points of the first low-melting-point component 31 and the second low-melting-point component 32. This prevents the humidity conditioner 20 from melting when bonding the substrates 10 together or when performing heat pressing in the manufacturing process described below, thereby minimizing deterioration of humidity-conditioning performance. Here, particulate means fine particles that make up a solid substance, and includes powder and fine particles.

[0035] The humidity-conditioning component 22 may be held not only in the water absorbent 21 but also in a support that supports the humidity-conditioning element 20 .

[0036] The moisture-conditioning component 22 may be present inside the water absorbent body 21, or may be present separately and mixed.

[0037] Specific examples of the humidity-conditioning component 22 include salts, such as sodium formate, potassium formate, sodium propionate, potassium propionate, potassium carbonate, calcium carbonate, sodium acetate, potassium acetate, lithium acetate, ammonium acetate, sodium lactate, potassium lactate, calcium chloride, lithium chloride, magnesium chloride, potassium chloride, sodium chloride, zinc chloride, aluminum chloride, magnesium chloride, lithium bromide, calcium bromide, potassium bromide, sodium hydroxide, citric acid, and sodium pyrrolidonecarboxylate. These salts can absorb moisture or deliquesce with increasing relative humidity and have high moisture absorption capacity. At particularly high humidity (e.g., 80% RH or higher), the humidity-conditioning component 22 can absorb a large amount of water per weight, making it effective in suppressing condensation and fogging that occur at high humidity. Among these, carboxylates (sodium formate, sodium propionate, sodium acetate) that have a threshold humidity-conditioning property at a specific humidity level and carbonates (sodium carbonate, potassium carbonate) with particularly low corrosivity are preferred. By having a threshold value for humidity control properties, the film does not absorb moisture below a certain relative humidity, enabling production without the need to maintain extremely low humidity in the manufacturing and storage environments. On the other hand, because it has high moisture absorption capacity above a certain relative humidity, it is effective in suppressing condensation and fogging that occur at high humidity. Among carboxylates, sodium formate and sodium propionate are more preferred because they exhibit small hysteresis in moisture absorption and desorption (the behavior of the moisture weight retained by the humidity control component 22 at equilibrium at a certain relative humidity, which differs between absorbing and desorbing moisture, even at the same relative humidity). Because of their small hysteresis, they can absorb moisture at high humidity, then release a certain amount of moisture and be regenerated when the humidity environment changes to a low humidity environment. At least one of these salts is preferred.

[0038] Furthermore, from the viewpoint of improving humidity-controlling performance and compensating for drawbacks, it is also preferable to contain two or more of these salts. In particular, the above-mentioned carbonate salts alone exhibit alkaline properties, and when combined with the above-mentioned carboxylate salts, it is expected that they will have the effect of preventing odors caused by liberation of carboxylic acid and volatilization of components, so it is also preferable to use these salts in combination.

[0039] The humidity control component 22 may contain an organic component such as a polyhydric alcohol in addition to the above-mentioned salt.

[0040] 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 preferably used. The polyhydric alcohol may form a dimer or a polymer. Furthermore, only one type may be contained, or two or more types may be contained.

[0041] The water absorbent body 21 preferably contains at least one selected from the group consisting of water-absorbent resins (particles, powder) and clay minerals. This allows the water absorbent body 21 to favorably retain the humidity-conditioning component 22, further enhancing the humidity-conditioning effect. As described above, the water absorbent body 21 functions to retain moisture when the humidity-conditioning component 22 excessively absorbs water vapor from the air. However, since the water absorbent body 21 is selected from the group consisting of water-absorbent resins and clay minerals, the water-absorbent body 21 has a high water-absorbing capacity, which further suppresses leakage of moisture or an aqueous solution containing the humidity-conditioning component 22 from the humidity-conditioning member 100.

[0042] Specific examples of the water-absorbent resin material include ionic resins and nonionic resins. Examples of the ionic resin include alkali metal salts of polyacrylic acid (such as sodium polyacrylate) and starch-acrylate graft polymers, with alkali metal salts of polyacrylic acid being preferred. Specific examples of alkali metal salts of polyacrylic acid include sodium polyacrylate. Examples of the nonionic resin include vinyl acetate copolymers, maleic anhydride copolymers, polyvinyl alcohol, and polyalkylene oxides.

[0043] Specific examples of clay minerals include silicate minerals such as smectite, sepiolite, attapulgite, kaolinite perlite, and dolomite, and zeolites.

[0044] When the humidity-conditioning component 22 is present, the weight ratio of its total weight to the water absorbent body 21 is preferably 1:1 to 3:7. In this way, the amounts of the water absorbent body 21 and the humidity-conditioning component 22 become appropriate, and the humidity-conditioning function can be further improved. Furthermore, if the proportion of the humidity-conditioning component 22 is too high, there is a high risk of water separation in a high humidity range, and if the proportion of the humidity-conditioning component 22 is too low, the humidity-conditioning moisture amount (the amount of water vapor that the humidity conditioner can absorb or release per weight) may be small.

[0045] The humidity control material 20 may be in the form of a powder, particles, or block, or the humidity control component 22 and the water absorbent material 21 may be supported on a breathable substrate so as to be efficiently in contact with air.

[0046] The humidity conditioner 20 also includes A-type silica gel, B-type silica gel, zeolite, polymeric sorption material, and the like.

[0047] As described above, the humidity-conditioning layer 23 has the second low-melting-point component 32 having a melting point lower than that of the first low-melting-point component 31. The melting point of the second low-melting-point component 32 is preferably about 70 to 120°C.

[0048] The second low-melting point component 32 may be any material that can bond the humidity conditioners 20 together and the humidity conditioner layer 23 to the substrate 10 by heat fusion, and may be a thermoplastic resin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyvinyl acetate, saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyester, polyamide, polyurethane, ionomer resin, or a modified product thereof, preferably a thermoplastic resin such as polyvinyl acetate, saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyester, polyamide, polyurethane, ionomer resin, or a modified product thereof. These may be used alone or in combination of two or more.

[0049] As described above, the humidity control member 100 according to the present disclosure includes at least a substrate 10 made of fibers and a humidity control layer 23. Furthermore, the components of the high-melting-point fibers 11 contained in the substrate 10 and the humidity control body 20 can be detected by component analysis such as FT-IR or EDX. Furthermore, the moisture absorption rate of the humidity control body 20 at a relative humidity of 90% (the ratio of the weight increase due to absorption of water vapor to the dry weight) is 30% or more.

[0050] DSC (differential scanning calorimetry) measurement of the substrate 10 reveals melting in two stages (melting point of the high-melting-point fiber 11 / first low-melting-point component 31), and DSC measurement of the humidity-conditioning layer 23 reveals melting due to the second low-melting-point component 32. The respective melting points show the relationship: second low-melting-point component 32 < first low-melting-point component 31 < high-melting-point fiber 11.

[0051] The internal structure of the substrate 10 and the humidity-conditioning layer 23 can be confirmed by observing their cross sections with an optical microscope, an electron microscope (SEM), or the like. It can be confirmed that the substrate 10 contains a first low-melting-point component 31 that is heat-fusible with the high-melting-point fibers 11, and that it contains regions 311 in which the high-melting-point fibers 11 are fused together via the first low-melting-point component 31 upon melting of the first low-melting-point component 31. It can be confirmed that the humidity-conditioning layer 23 contains a second low-melting-point component 32, and that it contains regions in which humidity conditioners 20 are fused together, the humidity conditioner 20 and the substrate 10, or the substrates 10 are fused together.

[0052] 9 is a diagram illustrating a simplified method for manufacturing a humidity control member 100 according to the present disclosure. First, a substrate 10 including a first low-melting-point component 31 that is not fused to the high-melting-point fiber 11, a humidity control body 20, and a second low-melting-point component 32 that is not fused are prepared, and the humidity control body 20 and the second low-melting-point component 32 are sandwiched between the two substrates 10.

[0053] Next, in the first processing step, the components are bonded together by heating and pressure at a temperature higher than the temperature at which the second low-melting point component 32 fuses and lower than the temperature at which the first low-melting point component 31 fuses. At this time, only the second low-melting point component 32 melts, fusing the humidity conditioners 20 together to form the humidity-conditioning layer 23, and further fusing and integrating the humidity-conditioning layer 23 with the substrate 10 and the substrates 10 together.

[0054] Next, as a second process, the first low-melting-point component 31 is heat-pressed at a temperature equal to or higher than the melting point of the first low-melting-point component 31. In this way, the first low-melting-point component 31 fuses with the high-melting-point fibers 11 in a compressed state, producing a rigid humidity control member 100. At this time, the first low-melting-point component 31 melts, creating regions 311 where the high-melting-point fibers 11 are fused together via the first low-melting-point component 31. During heat pressing, spacers of a predetermined length and height are provided on a portion of the periphery of the region required for the product. This causes the aforementioned fusion to occur and fix the overall thickness of the humidity control member 100 at a height close to the predetermined height, allowing the humidity control member 100 to maintain its shape with that overall thickness even after heat pressing. In this way, the overall thickness of the humidity control member 100 can be adjusted.

[0055] In this embodiment, the inclusion of the second low-melting-point component 32 in the humidity-conditioning layer 23 allows for continuous processing up to the first processing step in roll form, improving mass production. Alternatively, the humidity-conditioning layer 23 also has more fusion points internally, improving the rigidity of the resulting humidity-conditioning member 100. Therefore, it is more preferable for the humidity-conditioning layer 23 to include the second low-melting-point component 32. While the above-described manufacturing method has been described as including the second low-melting-point component 32 in the humidity-conditioning layer 23, even without the second low-melting-point component 32, sandwiching the humidity conditioner 20 between two substrates 10 and performing the heat pressing step in the second processing step allows the first low-melting-point component 31 to fuse and integrate the entire humidity-conditioning member 100, thereby obtaining a humidity-conditioning member 100 that combines humidity-conditioning function and rigidity.

[0056] FIG. 10 is a diagram showing how the humidity control member 100 according to the present disclosure is molded using a mold 40 of the desired shape. As shown in FIG. 10 , in the second processing step described above, the humidity control member 100 according to the present disclosure can be molded into the desired shape along the mold 40 by heat pressing the mold 40 at a temperature equal to or higher than the melting point of the first low-melting-point component 31. By doing so, the first low-melting-point component 31 fuses and fixes the high-melting-point fiber 11 when the humidity control member 100 is compressed and molded into the desired shape, making it possible to maintain the molded state. The shape of the humidity control member 100 according to the present disclosure may be, for example, a box-like shape as shown in FIG. 11 , or a plate-like or boat-like shape. In this way, a molded product of a three-dimensional shape may be formed by heat pressing. Since the substrate 10 is breathable even in a compressed state, as described below, its humidity control performance is not reduced even when heat-pressed using a mold 40.

[0057] Furthermore, the humidity control member 100 according to the present disclosure can be provided with a microstructure pattern on its surface. This increases the surface area, making it possible to further increase the humidity control speed. If the size of the humidity control member 100 is large, warping may occur during the hot pressing step in the second processing step. However, providing a periodic structure pattern can also minimize this warping. There are no particular limitations on the shape of the microstructure.

[0058] Fig. 12 is a diagram showing a humidity control member 100 in which a moisture-impermeable layer 50 is provided on one of the two substrates 10, on the surface opposite to the surface that contacts the humidity-conditioning layer 23. The humidity control member 100 according to the present disclosure may include a moisture-impermeable layer 50 on one of the two substrates 10, on the surface opposite to the surface that contacts the humidity-conditioning layer 23. The humidity control member 100 shown in Fig. 12 includes a moisture-impermeable layer 50 on the lower surface of the substrate 10. The moisture-impermeable layer 50 is made of a material that does not or has low permeability to water molecules, and examples of the moisture-impermeable layer 50 include a resin sheet, an aluminum-deposited film, a metal plate, etc. that do not have a porous structure.

[0059] Alternatively, the humidity control member 100 having the moisture-impermeable layer 50 on the underside of the substrate 10 may be heat-pressed to form a three-dimensional molded product as shown in Fig. 13. The molded product may be covered with a lid or the like to store an object to be humidity-controlled. This allows the humidity control performance to be concentrated on the side opposite the moisture-impermeable layer 50, and the humidity of an object stored inside the molded product, i.e., inside a container made of the molded product, can be effectively controlled.

[0060] The humidity control member 100 according to the present disclosure will be specifically described below using examples and comparative examples, but the present invention is not limited to the examples described here.

[0061] (Example 1) A substrate containing a high melting point fiber and a first low melting point component was prepared. Both of the upper and lower substrates had a basis weight of 100 g / m ２ The high-melting-point fiber was polyester. The first low-melting-point component was low-melting-point PET (melting point 110°C). The composition ratio of the high-melting-point fiber to the first low-melting-point component was 50% (weight part of the first low-melting-point component relative to the total weight of the high-melting-point fiber and the first low-melting-point component (hereinafter simply referred to as the first low-melting-point component ratio). The substrate had a core-sheath structure in which the outer periphery of the high-melting-point fiber was covered with the first low-melting-point component.

[0062] The humidity conditioner was a mixture of carboxylate (sodium propionate) and sodium carbonate in a ratio of 3:1 as the humidity-conditioning component, and water-absorbent resin (sodium polyacrylate) was used as the water-absorbent body 21. The average particle diameters of the respective components were 300 μm for sodium propionate, 400 μm for sodium carbonate, and 500 μm for sodium polyacrylate. The basis weight of the humidity-conditioning layer containing the second low-melting-point component and the humidity conditioner was 80 g / m ２ The second low-melting point component was polyethylene (melting point 80°C). The melting points of the components contained in the humidity conditioner were 289°C for sodium propionate, 851°C for sodium carbonate, and 150°C for sodium polyacrylate, which were higher than the melting points of the first low-melting point component and the second low-melting point component.

[0063] The thickness of each substrate is 1.0 mm and the density is 0.10 g / m ３ It was decided.

[0064] The humidity-conditioning layer was sandwiched between substrates and pressed and bonded at 100°C, which is higher than the temperature at which the second low-melting point component fuses but lower than the temperature at which the first low-melting point component fuses (first processing). Then, a spacer having a thickness of 1.0 mm was placed and pressed at 120°C, which is higher than the temperature at which the first low-melting point component fuses, to produce a plate-shaped humidity-conditioning member according to Example 1 (second processing).

[0065] After pressing (thermal compression), the humidity control member according to Example 1 had a thickness of 1.0 mm and a density of 0.20 g / m ３ It was.

[0066] (Example 2) In Example 2, a sheet of a substrate having a basis weight of 200 g / m ２ The first low-melting point component ratio was set to 30%. The thickness of one substrate was set to 2.0 mm. The spacer in the second processing was set to 2.0 mm. The other conditions were the same as those in Example 1.

[0067] After pressing (thermal compression), the humidity control member according to Example 2 had a thickness of 2.0 mm and a density of 0.20 g / m ３ It was.

[0068] (Example 3) In Example 3, a sheet of a substrate having a basis weight of 200 g / m ２ The first low-melting point component ratio was set to 40%. The thickness of each substrate was set to 2.0 mm. The spacer in the second processing was set to 2.0 mm. The other conditions were the same as those in Example 1.

[0069] The humidity control member according to Example 3 after pressing (thermal compression) had a thickness of 2.0 mm and a density of 0.20 g / m ３ It was.

[0070] (Example 4) In Example 4, a sheet of a substrate having a basis weight of 350 g / m ２ The thickness of one substrate was 3.0 mm and the density was 0.12 g / m ３ The spacer in the second processing was set to 3.0 mm. Other than that, the manufacturing conditions were the same as those in Example 1.

[0071] The humidity control member according to Example 4 after pressing (thermal compression) had a thickness of 3.0 mm and a density of 0.23 g / m ３ It was.

[0072] (Example 5) In Example 5, a sheet of a substrate having a basis weight of 600 g / m ２ The thickness of one substrate was 4.0 mm and the density was 0.15 g / m ３ The spacer in the second processing was set to 4.0 mm. Other than that, the manufacturing conditions were the same as in Example 1.

[0073] The humidity control member according to Example 5 after pressing (thermal compression) had a thickness of 4.0 mm and a density of 0.30 g / m ３ It was.

[0074] (Comparative Example 1) In Comparative Example 1, a substrate was prepared that did not contain the first low-melting component and was composed only of high-melting fiber. The weight of one substrate was 50 g / m ２ The high-melting-point fiber was polyester. The substrate did not contain the first low-melting-point component. Furthermore, heat pressing (thermal compression) was not performed. In this manner, a humidity control member according to Comparative Example 1 was produced.

[0075] The above conditions and results are shown in Table 1.

[0076]

[0077] As shown in Table 1, in all examples, the substrate contained a first low-melting component heat-fusible with the high-melting fiber, and the high-melting fiber and the first low-melting component were fused together, resulting in a bending rigidity of 500 MPa or more, measured as a representative value of rigidity. Therefore, all examples achieved good rigidity results. Furthermore, despite the heat pressing, the humidity conditioner was particulate with an average particle size of 50 to 1000 μm. When the substrate side was heat pressed, the first low-melting component melted and fused the high-melting fiber together, resulting in uneven density and possibly areas where the pores of the high-melting fiber became larger. However, almost no humidity conditioner was observed to fall off from the substrate. Furthermore, the use of a second low-melting component in the humidity-conditioning layer strengthened the bonding strength between the substrates and between the substrate and the humidity-conditioning layer, and almost no humidity conditioner was observed to fall off from the edge of the substrate.

[0078] On the other hand, in Comparative Example 1, in which heat pressing (thermal compression) was not performed, the base material did not contain a first low-melting point component that could be heat-fused to the high-melting point fiber, and the fibers were simply physically entangled with each other and not fused, resulting in poor rigidity.

[0079] Furthermore, the humidity control speeds of the humidity control members according to the examples and comparative examples manufactured as described above were compared when the humidity control members were left standing in a high humidity environment.

[0080] The conditions for leaving the humidity control member in a high humidity environment were as follows: the humidity control member was cut into 10 cm square pieces, and left to stand for 24 hours in a constant temperature and humidity chamber at a temperature of 23°C and a humidity of 40% RH, and the initial weight was measured. The humidity control member was then left to stand for 10 minutes in a constant temperature and humidity chamber at a temperature of 23°C and a humidity of 90% RH, and the weight was then measured. The change in weight (grams) was divided by the humidity control member area (0.01 square meters) and the elapsed time (10 minutes) to calculate the humidity control rate per unit time and unit area.

[0081] The results of the humidity control speed are shown in FIG.

[0082] As shown in FIG. 13, the humidity control members according to all of the examples showed results equivalent to those of Comparative Example 1, which was not subjected to heat pressing, and had excellent breathability of the substrate and humidity control properties of the humidity control member.

[0083] The weight of the substrate is 100 to 600 g / m ２ , density 0.20~0.30g / m ３ Within this range, regardless of the composition ratio of the high-melting-point fiber and the first low-melting-point component, the humidity control speed was comparable to that of the nonwoven fabric of Comparative Example 1, which had no rigidity and a small basis weight and density (basis weight 50 g / m ２ , density 0.1g / m ３ ) was equivalent to that of Comparative Example 1. Therefore, in the humidity-conditioning members according to all Examples, the breathability of the substrate was maintained after heat pressing, and the humidity-conditioning performance was also maintained. It is believed that the humidity-conditioning function is not reduced even when the basis weight and density are increased by compressing and fusing the substrate while leaving the porous structure consisting of the gaps between the fibers in the substrate. Furthermore, since the humidity-conditioning body is composed of a water-absorbing body and a humidity-conditioning component, and the melting points of each are higher than the melting points of the first low-melting point component and the second low-melting point component, it is believed that the humidity-conditioning performance is comparable to that of Comparative Example 1, despite the heat pressing.

[0084] As described above, according to the present disclosure, it is possible to provide a humidity control member 100 that has high humidity control function and rigidity.

[0085] 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.

[0086] 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 configuration and operation of the humidity control member 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 member comprising at least two substrates and a humidity-conditioning layer between the substrates, the humidity-conditioning layer containing a humidity-conditioning material that absorbs or releases water vapor, wherein the substrates are breathable and contain a first low-melting component that can be heat-fused to high-melting fibers, and the humidity-conditioning member includes at least a portion where the high-melting fibers are fused together via the first low-melting component due to melting of the first low-melting component.

2. The humidity-conditioning element according to claim 1, characterized in that the humidity-conditioning layer contains a second low-melting point component having a melting point temperature lower than that of the first low-melting point component, and the second low-melting point component fuses the humidity-conditioning elements together, the humidity-conditioning element and the substrate, or the substrates together.

3. The humidity control member according to claim 1 or 2, wherein the first low melting point component is in the form of fibers or particles.

4. A humidity control member according to claim 1 or 2, characterized in that the first low melting point component is fibrous and is present on at least a portion of the periphery of the high melting point fiber, thereby forming the fibrous form.

5. The humidity-regulating member according to claim 1 or 2, characterized in that the composition ratio of the high-melting point fiber and the first low-melting point component in the base material is such that the weight of the first low-melting point component is 20 to 60% of the total weight of the high-melting point fiber and the first low-melting point component.

6. The humidity control member according to claim 1 or 2, wherein the humidity control material is in particulate form.

7. The humidity control member according to claim 6, wherein the substrate is porous and the particle diameter of the humidity control agent is larger than the pores.

8. The humidity control member according to claim 6, wherein the humidity control agent has an average particle size of 50 μm to 1000 μm.

9. The humidity control member according to claim 1 or 2, characterized in that the bending rigidity is 500 MPa or more.

10. The humidity control member according to claim 1 or 2, characterized in that it has a plate-like, box-like or boat-like shape.

11. The humidity control member according to claim 1 or 2, characterized in that one of the two substrates has a moisture-impermeable layer on the surface opposite to the surface in contact with the humidity control layer.

12. The humidity control member according to claim 1 or 2, characterized in that the humidity control body comprises a water absorbent and a humidity control component.

13. The humidity control member according to claim 12, wherein the humidity control component contains a salt.

14. The humidity control member according to claim 13, wherein the salt is a carboxylate, and is at least one selected from the group consisting of sodium formate, sodium propionate, and sodium acetate.

15. The humidity control member according to claim 13, wherein the salt is a carbonate, and is at least one selected from the group consisting of sodium carbonate and potassium carbonate.

16. The humidity-controlling member according to claim 13, characterized in that the salt contains two or more types of salt, each selected from a carboxylate and a carbonate, the carboxylate being at least one selected from the group consisting of sodium formate, sodium propionate, and sodium acetate, and the carbonate being at least one selected from the group consisting of sodium carbonate and potassium carbonate.

17. The humidity control member according to claim 12, wherein the water absorbent is at least one selected from the group consisting of water-absorbent resins and clay minerals.

18. The humidity control member according to claim 12, wherein the melting points of the water absorbent and the humidity control component are higher than the melting point of the first low-melting component.

Images