Desiccant element

Abstract

By using PEDOT and PSS, a desiccant element is provided that ensures dehumidification performance and regenerates by removing adsorbed moisture through heat generated by the application of electricity. [Solution] The desiccant element has a substrate and a water-absorbing layer. At least one of the interior and surface of the substrate holds a composite or salt thereof consisting of PEDOT (poly(3,4-ethylenedioxythiophene)) and PSS (polystyrene sulfonic acid). The water-absorbing layer is formed of a water-absorbing polymer and is provided on the substrate. The desiccant device has a desiccant element and allows air to flow along the surface of the desiccant element.

Description

Technical Field

[0001] The present invention relates to a desiccant element that adsorbs moisture in the air for dehumidification and removes and regenerates the adsorbed moisture by heat generated during energization.

Background Art

[0002] Patent Document 1 discloses a desiccant filter having a sheet-like substrate and a desiccant laminated on the surface of the substrate. As the substrate, a substrate containing a conductive material inside or a substrate having a surface layer formed of a conductive material is used. Further, as the conductive material, PEDOT / PSS (a composite composed of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid) is used, and as the desiccant, activated carbon is used. This technology aims to provide an excellent desiccant device capable of adsorbing high-concentration water vapor. However, activated carbon is a fine powder and requires measures to prevent scattering and explosion during handling, and there is concern about peripheral contamination when it falls off because activated carbon is black, and its improvement has been desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a desiccant element that ensures conductivity and dehumidification performance by using PEDOT and PSS, and removes and regenerates the adsorbed moisture by heat generated during energization.

Means for Solving the Problems

[0005] The desiccant element according to the first invention of this application comprises a substrate and a water-absorbing layer. At least one of the interior and surface of the substrate holds a composite and / or a salt of this composite consisting of PEDOT (poly(3,4-ethylenedioxythiophene)) and PSS (polystyrene sulfonic acid). The water-absorbing layer is formed of a water-absorbing polymer and is provided on the substrate.

[0006] The desiccant device, which is the second invention of this application, has a desiccant element, which is the first invention of this application, and circulates air along the surface of the desiccant element. [Effects of the Invention]

[0007] According to the present invention, moisture from the air can be adsorbed using the water-absorbing layer, and the adsorbed moisture can be removed by the heat generated when current is passed through the composite of PEDOT and PSS, thereby regenerating the desiccant element. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a desiccant element in which water-absorbing layers are formed on both sides of the substrate. [Figure 2] This is a schematic diagram of a desiccant element in which a water-absorbing layer is formed on one side of the substrate. [Figure 3] This is a schematic diagram of a desiccant element in which a PEDOT / PSS layer and a water-absorbing layer are formed on one side of the substrate. [Figure 4] This is a schematic diagram of a desiccant element in which a PEDOT / PSS layer and a water-absorbing layer are formed on both sides of the substrate. [Figure 5] This is a schematic diagram of a desiccant apparatus. [Modes for carrying out the invention]

[0009] <Configuration of a desiccant element> Figure 1 is a schematic diagram of a desiccant element 10, which is an embodiment of the present invention. The desiccant element 10 has a substrate 11 that holds PEDOT / PSS and / or a salt of PEDOT / PSS, and a water-absorbing layer 12 formed on the surface of the substrate 11. PEDOT / PSS is a conductive composite consisting of poly(3,4-ethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS). The water-absorbing layer 12 is a layer formed of a water-absorbing polymer. The desiccant element 10 can be processed into various shapes depending on the application.

[0010] PEDOT / PSS and / or a salt of PEDOT / PSS (hereinafter simply referred to as "PEDOT / PSS") may be held inside the substrate 11, held on the surface of the substrate 11, or held both inside and on the surface of the substrate 11.

[0011] When PEDOT / PSS is held inside the substrate 11, the substrate 11 can be anything that can hold PEDOT / PSS inside, for example, a nonwoven fabric can be used. The fibers that make up the nonwoven fabric are not particularly limited, but for example, aramid fibers, cellulose fibers, nylon fibers, vinylon fibers, glass fibers, polyester fibers, polyethylene fibers, polypropylene fibers, polyolefin fibers, and rayon fibers can be used. Here, one type of fiber can be used, or multiple types of fibers can be used in combination.

[0012] When PEDOT / PSS is held on the surface of the base 11, various materials can be used for the base 11. Furthermore, a space for holding PEDOT / PSS does not need to be formed inside the base 11. When PEDOT / PSS is held on the surface of the base 11, for example, a sheet-like member formed from PEDOT / PSS can be fixed to the surface of the base 11.

[0013] In the desiccant element 10 shown in Figure 1, the water-absorbing layer 12 is provided on both sides of the substrate 11, but as shown in Figure 2, the water-absorbing layer 12 may be provided on only one side of the substrate 11. The water-absorbing layer 12 may be a sheet-like member made of a water-absorbing polymer, or it may be composed of a holder that holds the water-absorbing polymer. This holder can be anything that can hold the water-absorbing polymer, for example, the nonwoven fabric described above can be used. The water-absorbing layer 12 can be fixed to the surface of the substrate 11.

[0014] On the other hand, as shown in Figure 3, a layer 13 made of PEDOT / PSS (hereinafter referred to as the "PEDOT / PSS layer") can be provided on one side of the substrate 11, and a water-absorbing layer 12 can be provided on the surface of the PEDOT / PSS layer 13. Also, as shown in Figure 4, a layer 13 made of PEDOT / PSS (hereinafter referred to as the "PEDOT / PSS layer") can be provided on both sides of the substrate 11, and a water-absorbing layer 12 can be provided on the surface of each PEDOT / PSS layer 13.

[0015] On the other hand, the substrate 11 and the water-absorbing layer 12 can also be constructed integrally. Specifically, in the retainer constituting the substrate 11 and the water-absorbing layer 12, a layer that holds PEDOT / PSS (corresponding to the substrate 11) and a layer that holds the water-absorbing polymer (corresponding to the water-absorbing layer 12) can be formed. Here, the layer that holds the water-absorbing compound is located on the surface of the desiccant element 10.

[0016] As the water-absorbing polymer, at least one of PSS and PSS salts can be used. Examples of PSS salts include ammonium salts, alkali metal salts, alkaline earth metal salts, and amine salts.

[0017] Furthermore, PSS derivatives, cellulose derivatives, polyvinyl alcohol derivatives, polyacrylic acid derivatives, polyvinyl alcohol derivatives, and polyvinylpyrrolidone can be used as the superabsorbent polymers. Here, one type of superabsorbent polymer can be used alone, or multiple types of superabsorbent polymers can be used in combination.

[0018] Examples of the PSS derivative include a copolymer of polystyrene sulfonic acid and maleic acid and its salt, and a copolymer of polystyrene sulfonic acid and N-substituted maleimide. Examples of the cellulose derivative include carboxymethyl cellulose, methyl cellulose, ethyl cellulose, and propyl cellulose. Examples of the polyvinyl alcohol derivative include a saponified product of polyvinyl alcohol. Examples of the polyacrylic acid derivative include a copolymer of polyacrylic acid and methyl polyacrylate. Examples of the polyvinyl alcohol derivative include polyvinyl alcohol with a saponification degree of 95%.

[0019] PSS is particularly preferred as the water-absorbing polymer. The weight average molecular weight of PSS is preferably 10,000 or more and 1,000,000 or less, and more preferably 50,000 or more and 500,000 or less. The weight average molecular weight is the average molecular weight based on mass measured using gel permeation chromatography and determined in terms of pullulan.

[0020] The content of PSS in PEDOT / PSS is preferably, for example, 0.5 mol or more and 50 mol or less, more preferably 1 mol or more and 30 mol or less, and even more preferably 2 mol or more and 25 mol or less with respect to 1 mol of PEDOT. An optimal PEDOT / PSS can be obtained with a content ratio having a desired conductivity as appropriate within these molar ranges.

[0021] In addition to retaining PEDOT / PSS, the substrate 11 may retain an additive. Further, the water-absorbing layer 12 may contain an additive in addition to the water-absorbing polymer. Examples of this additive include a surfactant, an inorganic conductive agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, a binder, and a non-water-absorbing resin used together with the water-absorbing polymer.

[0022] Examples of surfactants include nonionic surfactants, anionic surfactants, and cationic surfactants, but nonionic surfactants are preferred in terms of storage stability. Polymer surfactants such as polyvinyl alcohol and polyvinylpyrrolidone may also be added. Examples of inorganic conductive agents include metal ions and conductive carbon. Metal ions can be generated by dissolving metal salts in water.

[0023] Examples of defoaming agents include silicone resins, polydimethylsiloxanes, and silicone oils. Examples of antioxidants include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, and sugars. Examples of ultraviolet absorbers include benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, salicylate ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, oxanilide ultraviolet absorbers, hindered amine ultraviolet absorbers, and benzoate ultraviolet absorbers. Furthermore, to enhance the conductivity of PEDOT / PSS, carbon nanotubes (CNTs) or metal nanoparticles (such as AgNP) may be added, or ethylene glycol, diethylene glycol, DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), N-methylpyrrolidone, sulfuric acid, GOPS ((glycidyloxypropyl) trimethoxysilane), MoO2, etc.

[0024] Examples of non-absorbent resins used with superabsorbent polymers include latex or aqueous dispersions of acrylic resin, vinyl acetate resin, polyester resin, polyurethane resin, rubber resin, vinyl chloride resin, vinylidene chloride resin, polyolefin resin, or copolymers thereof.

[0025] Since a water-absorbing layer 12 is provided on the surface of the desiccant element 10, moisture contained in the air can be adsorbed onto the water-absorbing layer 12. Furthermore, by connecting a power supply to the substrate 11 and applying a voltage to the PEDOT / PSS held in the substrate 11, the PEDOT / PSS can be heated, and the moisture adsorbed onto the water-absorbing layer 12 can be released into the air.

[0026] In the electrical connection portion of the substrate 11 to the power supply, the PEDOT content can be higher than the PSS content. This makes it easier to apply voltage to the PEDOT / PSS held in the substrate 11.

[0027] <Method for manufacturing a desiccant element> In a reaction vessel containing a reaction solution comprising monomers that form PEDOT (hereinafter simply referred to as "monomers"), PSS, and an aqueous dispersion medium, the monomers are polymerized to form PEDOT. Here, PSS dops the PEDOT, yielding PEDOT / PSS dispersed in the aqueous dispersion medium.

[0028] Since the aqueous dispersion medium contained in the reaction solution contains water, the polymerization reaction of the monomer proceeds stably, and the resulting PEDOT / PSS is obtained in a dispersed state in the aqueous dispersion medium. The water content relative to the total mass of the aqueous dispersion medium is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and may be 100% by mass (i.e., water only).

[0029] The aqueous dispersion medium may contain a dispersion medium other than water. The dispersion medium other than water should not inhibit monomer polymerization, and water-soluble organic solvents are preferred. Examples of water-soluble organic solvents include alcohol-based solvents, ketone-based solvents, and ester-based solvents. A single water-soluble organic solvent may be used, or two or more may be used in combination.

[0030] A catalyst and an oxidizing agent can be added to the reaction solution to promote the chemical oxidation of the monomer. Examples of catalysts include transition metal compounds such as ferric chloride, ferric sulfate, ferric nitrate, and cupric chloride. Examples of oxidizing agents include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. It is preferable to remove the catalyst and oxidizing agent added to the reaction solution after the polymerization reaction of the monomer is completed.

[0031] The monomer content relative to the total mass of the reaction solution is preferably, for example, 0.01% by mass or more and 2.0% by mass or less, more preferably 0.1% by mass or more and 1.0% by mass or less, and even more preferably 0.3% by mass or more and 0.5% by mass or less. The PSS content relative to the total mass of the reaction solution is preferably, for example, 0.1% by mass or more and 3.0% by mass or less, more preferably 0.5% by mass or more and 2.0% by mass or less, and even more preferably 1.0% by mass or more and 1.5% by mass or less. In the reaction solution, the PSS content relative to the monomer is preferably in the range of 1 part by mass or more and 1000 parts by mass or less per 100 parts by mass of monomer, more preferably 10 parts by mass or more and 700 parts by mass or less, and even more preferably 100 parts by mass or more and 500 parts by mass or less.

[0032] The reaction temperature (the temperature of the reaction solution) when polymerizing monomers can be, for example, 20-30°C. Within this temperature range, the polymerization reaction of monomers can be completed in approximately 4-12 hours. The completion of the polymerization reaction can be determined by measuring the amount of unreacted monomer in the reaction solution using methods such as gas chromatography.

[0033] To retain PEDOT / PSS inside the substrate 11, the substrate 11 can be impregnated with an aqueous dispersion medium containing dispersed PEDOT / PSS, and then dried. On the other hand, to retain PEDOT / PSS on the surface of the substrate 11, the aqueous dispersion medium containing dispersed PEDOT / PSS can be applied to the surface of the substrate 11, and then dried.

[0034] Next, an absorbent layer 12 is formed on the substrate 11 holding PEDOT / PSS. When a sheet-like member made of PSS is used as the absorbent layer 12, the sheet-like member can be formed using PSS, and then laminated and fixed onto the substrate 11. Alternatively, when a retainer (such as a nonwoven fabric) holding an absorbent polymer is used as the absorbent layer 12, the retainer can be impregnated with an aqueous dispersion medium in which the absorbent polymer is dispersed, and then dried to allow the retainer to hold the absorbent polymer. The retainer with the absorbent polymer can then be laminated and fixed onto the substrate 11.

[0035] As described above, when the substrate 11 and the water-absorbing layer 12 are integrally constructed, a portion of the retainer constituting the substrate 11 and the water-absorbing layer 12 will hold PEDOT / PSS, while the other portion of the retainer will hold the water-absorbing polymer. Specifically, a layer that holds PEDOT / PSS can be formed on the retainer by impregnating a portion of the retainer with an aqueous dispersion medium in which PEDOT / PSS is dispersed, and then performing a drying treatment. Alternatively, a layer that holds the water-absorbing polymer can be formed on the retainer by impregnating the other portion of the retainer with an aqueous dispersion medium in which the water-absorbing polymer is dispersed, and then performing a drying treatment.

[0036] On the other hand, after applying PEDOT / PSS to the surface of the substrate 11 to form a PEDOT / PSS layer, the PSS contained in the PEDOT / PSS layer can be moved to the surface of the PEDOT / PSS layer by performing a chemical surface treatment (such as alcohol treatment) on the surface of the PEDOT / PSS layer, and the surface portion of the PEDOT / PSS layer (the layer corresponding to the water-absorbing layer 12) can be composed of PSS. As compounds used in the surface treatment, for example, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), methanol, and compounds having two hydroxyl groups (ethylene glycol, polyethylene glycol, etc.) can be used, and as a surface treatment method, the treatment solution can be sprayed onto the surface of the PEDOT / PSS layer.

[0037] Furthermore, when a hydrophobic nonwoven fabric is used as the substrate 11, when PEDOT / PSS is retained on the substrate 11, the hydrophilic PSS is more easily dispersed to a position away from the substrate 11, and the PSS is more easily concentrated in the surface layer of the substrate 11 (corresponding to the water-absorbing layer 12). The hydrophobic nonwoven fabric can be formed from synthetic fibers such as polyester and nylon.

[0038] <Desiccant apparatus> A desiccant device can be constructed using the desiccant elements 10 described above. Specifically, as shown in Figure 5, multiple desiccant elements 10 can be prepared, and a spacer 20 can be placed between two adjacent desiccant elements 10. This allows the space formed between two adjacent desiccant elements 10 to be used as an air passage, and by moving air through this passage, moisture contained in the air can be adsorbed onto the desiccant elements 10 (specifically, the water absorption layer 12).

[0039] Multiple desiccant elements 10 can be electrically connected in parallel. Here, it is preferable to adjust the electrical conductivity of PEDOT / PSS in each desiccant element 10, and the composition of PEDOT / PSS can be adjusted to achieve a desired electrical conductivity (for example, a surface resistance of 1 to 10E6Ω / □).

[0040] In this embodiment of the desiccant element 10, a hygroscopic water-absorbing layer 12 is formed on the surface of the desiccant element 10, making it easier for moisture from the air to be adsorbed in the water-absorbing layer 12. Furthermore, since the conductive PEDOT / PSS is held in the substrate 11, the desiccant element 10 can be heated by passing an electric current through the substrate 11 (PEDOT / PSS), thereby releasing the moisture adsorbed in the water-absorbing layer 12 to the outside of the desiccant element 10 and regenerating the desiccant element 10.

[0041] The desiccant element 10 consists of a substrate 11 that holds PEDOT / PSS and a water-absorbing layer 12. By forming the water-absorbing layer 12 with PSS, the desiccant element 10 can be constructed simply by providing PEDOT and PSS. [Explanation of symbols]

[0042] 10: Desiccant element, 11: Substrate, 12: Water absorption layer, 13: PEDOT / PSS layer, 20: Spacer

Claims

1. A substrate having a composite of PEDOT (poly(3,4-ethylenedioxythiophene)) and PSS (polystyrene sulfonic acid) and / or a salt of the composite held in at least one of its interior and surface, A desiccant element characterized by having a water-absorbing layer provided on the substrate and formed of a water-absorbing polymer.

2. The desiccant element according to claim 1, characterized in that the superabsorbent polymer is at least one of PSS and a salt of PSS.

3. The desiccant element according to claim 1, characterized in that the superabsorbent polymer is at least one selected from the group consisting of PSS derivatives, cellulose derivatives, polyvinyl alcohol derivatives, polyacrylic acid derivatives, polyvinyl alcohol derivatives, and polyvinylpyrrolidone.

4. The desiccant element according to claim 1, characterized in that the substrate has a surfactant.

5. The desiccant element according to claim 1, characterized in that the water-absorbing layer has a surfactant and / or a water-non-absorbent resin.

6. The desiccant element according to claim 1, characterized in that the water-absorbing layer is a sheet-like material.

7. The desiccant element is as described in any one of claims 1 to 3, A desiccant apparatus characterized by circulating air along the surface of the desiccant element.

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