Water adsorbent, water collecting device, and method for collecting water

Abstract

To reduce weight increase of a water adsorbent while maintaining an amount of water capable of being collected.SOLUTION: A water adsorbent 10 for adsorbing water from the air includes an electrode 12 and a water adsorption film 11. In the water adsorbent 10, the water adsorption film 11 has water repellency.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water adsorbent, a water collection device, and a water collection method. [Background technology]

[0002] Because the amount of water available as a water resource is constantly changing due to fluctuations in precipitation, there is a demand for water collection technology that is less susceptible to the effects of abnormal weather such as drought. One technique for capturing this type of water is to place a net in the mist, which causes water present in the air to be adsorbed onto the net as water droplets, thereby capturing the water. For example, Non-Patent Document 1 describes a method in which corona discharge is generated between an emitter and a wire mesh, causing charged water to be adsorbed onto the wire mesh, thereby efficiently collecting water in the air. Summary of the Invention [Problem to be solved by the invention]

[0003] In general, to increase the amount of water that can be collected, it is necessary to increase the area of ​​the mesh. However, in Non-Patent Document 1, since water is adsorbed using a highly wettable wire mesh, the amount of water that accumulates on the wire mesh increases. Therefore, as the amount of adsorbed water on the water adsorbent increases, the weight of the water adsorbent increases, and there is a limit to how much the area of ​​the wire mesh can be enlarged from the standpoint of durability. An object of the present invention is to reduce the weight increase of the water adsorbent while maintaining the amount of water that can be collected. [Means for solving the problem]

[0004] In order to solve the above problems, one embodiment of the present invention comprises: A water adsorbent that adsorbs water in the air, the water adsorbent has an electrode and a water adsorption film, The water adsorbent is characterized in that the water adsorption film has water repellency. Effect of the Invention

[0005] According to one embodiment of the present invention, the amount of water that can be collected can be maintained, while the weight increase of the water adsorbent can be reduced. [Brief description of the drawings]

[0006] [Figure 1] 1 is a schematic diagram of an example of a water adsorbent according to an embodiment of the present invention. [Diagram 2] 1 is a schematic diagram of an example of a water collection device according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic diagram showing an example of a water collection device according to an embodiment of the present invention, in which an electric field is formed. [Figure 4] FIG. 2 is a schematic diagram illustrating a state in which mist is generated and water is collected in an example of a water collecting device according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic diagram illustrating a state in which mist is generated and water is collected in an example of a water collecting device not according to the present invention. [Figure 6] 1 is a graph showing the change over time in weight of water adsorbed onto a water adsorbent in the water collection devices of Examples 1 to 5 and Comparative Examples 1 and 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiments.

[0008] (water adsorbent) The water adsorbent of the present invention is A water adsorbent that adsorbs water in the air, the water adsorbent has an electrode and a water adsorption film, The water adsorption film is characterized in that it has water repellency. It is a water adsorbent. The embodiment of the water adsorbent of the present invention is not particularly limited as long as it satisfies the above-mentioned requirements, and may include other members as necessary. According to the water adsorbent of the present invention, it is possible to reduce the increase in weight of the water adsorbent while maintaining the amount of water that can be collected.

[0009] In this specification and the like, the term "collect" refers to obtaining water from the air.

[0010] <Water in the Air> The water adsorbent of the present invention adsorbs water in the air. It is preferable that the water in the air has an electric charge. In this case, by creating a potential difference between the space in which the water in the air exists and the water adsorbent, the water in the air can be intensively adsorbed onto the water adsorbent, thereby making it possible to collect the water in the air with high efficiency. The water in the air includes, for example, water in the air such as fog, clouds, and steam.

[0011] <<Water drops>> The water in the air is preferably adsorbed by the water adsorbent and turns into water droplets. The water droplets may vary depending on the wettability of the adsorbent, but refer to water droplets having a diameter of more than 0.15 mm and not more than 10 mm, or a volume of 0.014 microliters or more and 4 milliliters or less. When the water in the air has an electric charge, the water in the air that is adsorbed by the water adsorbent becomes charged water droplets. The water droplets may include the electrically charged water droplets.

[0012] <<<Charged water droplets>>> The charged water droplets adsorbed on the water adsorbent may reach the Rayleigh limit.

[0013] -Rayleigh limit- The Rayleigh limit is the maximum amount of charge that a water droplet can hold, and when the charged water droplet reaches the Rayleigh limit, it emits microdroplets. Among the charged water droplets, those with a particularly high charge density are stabilized by being ejected as microdroplets. It is said that the amount of charge of the ejected microdroplets is about one-quarter of that of the charged water droplet (parent water droplet). It is also known that the amount of charge that a charged water droplet holds does not change with evaporation, and when the charged water droplet reaches the maximum amount of charge that it can hold (the Rayleigh limit) as it evaporates, it continues to eject microdroplets, releasing its charge into the air. The microdroplets are smaller than the water droplets described above and are so small that they cannot be seen with the naked eye, and refer to water droplets having a diameter of 0.001 mm or more and 0.15 mm or less, or a volume of 0.005 picoliters or more and 0.014 microliters or less. In the water adsorbent of the present invention, since the water adsorption film has water repellency, charged water droplets that have reached the Rayleigh limit are easily formed, and minute water droplets that split off from the charged water droplets can be collected. The maximum amount of charge that a charged water droplet can have (Rayleigh limit) is determined by the balance between the surface tension of the water and the Coulomb repulsive force, and the maximum amount of charge q [C] can be calculated by substituting the surface tension T [N / m] of the water and the radius of the droplet a [m] into the following equation.

[0014]

number

[0015] <Water adsorption membrane> The water-adsorbing film has water repellency. The water repellency of the water adsorption film reduces the wettability of the water adsorbent, and the amount of moisture that accumulates in the water adsorbent is smaller than that of a wire mesh with high wettability, so that the water adsorbent can maintain a low amount of adsorbed water. This makes it possible to reduce the weight increase of the water adsorbent while maintaining the amount of water that can be collected. Furthermore, by reducing the weight increase of the water adsorbent, the mechanical strength of the water adsorbent can be ensured, and the area of ​​the water adsorbent can be expanded. Suppressing the weight increase of the water adsorbent contributes to reducing the cost of the structure, such as by simplifying the reinforcing members. In addition, since the water adsorption film has water repellency, the size of the charged water droplets formed on the water adsorbent becomes smaller than that of a water adsorption film that does not have water repellency, and the charged water droplets are more likely to reach the Rayleigh limit. Then, minute water droplets continue to be released from the charged water droplets that have reached the Rayleigh limit, thereby suppressing the amount of adsorbed water on the water adsorbent.

[0016] The material contained in the water adsorption film is not particularly limited as long as it is a material that makes the water adsorption film water repellent, but it preferably contains a material having low surface energy, and further preferably contains a conductive material, and may also contain other organic substances, inorganic substances, combinations of these, etc.

[0017] In this specification and the like, the term "water repellency" refers to a static contact angle with water of 90° or more. The material contained in the water adsorption film is not particularly limited as long as it is a material that has water repellency, but from the viewpoint of processability, a material having low surface energy is preferred, specifically, a silicone resin is preferred, and a fluorine-based resin is more preferred.

[0018] -Materials with low surface energy- Suitable examples of the silicone resin include polydimethylsiloxane (PDMS), silicone rubber, modified silicone rubber, and fluorosilicone rubber. Suitable examples of the fluororesin include tetrafluoroethylene-polyethylene fluorovinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polytetrafluoroethylene (PTFE), a mixture of these fluororesins, and a heat-resistant resin having these fluororesins dispersed therein.

[0019] The content of the silicone resin in the water adsorption film is preferably from 50 to 100% by mass, more preferably from 80 to 100% by mass, and even more preferably from 90 to 100% by mass.

[0020] The content of the fluorine-based resin in the water adsorption film is preferably from 50 to 100% by mass, more preferably from 80 to 100% by mass, and even more preferably from 90 to 100% by mass.

[0021] As materials having low surface energy other than those mentioned above, it is preferable to use, for example, a material capable of forming a fine uneven structure such as the surface of a lotus leaf, which has a contact angle with water of 150° or more, a material into which a functional group has been introduced by chemical modification in order to reduce the surface free energy, etc. Specifically, for example, nanosilica, nanowhisker mixture, etc. are suitable materials, and examples of commercially available products include water repellent spray (Glaco Mirror Coat ZERO, manufactured by Soft99 Corporation) and Ultra Ever Dry Spray (manufactured by UltraTech International, Inc.).

[0022] -Conductive materials- The water adsorption film preferably further contains a conductive material. When the water adsorption film contains a conductive material, a conductive portion is formed in the water adsorption film, and therefore an electric field is also formed on the water adsorbent, which induces water adsorbed onto the water adsorbent and increases the contact probability between water molecules on the water adsorbent and the contact probability between the water adsorbent and water, thereby enabling effective adsorption of water. Examples of the conductive material include zinc oxide, titanium oxide, carbon fiber, carbon fiber (CF), carbon nanofiber (CNF), carbon nanotube (CNT), metal filler (gold, silver, platinum, copper, aluminum, etc.), conductive polymer material (any derivative of polythiophene, polyacetylene, polyaniline, polypyrrole, polyparaphenylene, and polyparaphenylenevinylene, or a derivative of these with a dopant such as an anion or a cation added thereto), and the like. The conductive material may be included as a filler.

[0023] The content of the conductive material in the water adsorption film is appropriately adjusted taking into consideration the dispersibility of the material while taking into account the surface properties and conductive contact properties, but is preferably 20 to 80 mass %, more preferably 30 to 60 mass %, and even more preferably 40 to 50 mass %.

[0024] --Conductive material having a needle-like shape-- The conductive material is preferably a conductive material having a needle-like shape. When the water adsorption film contains a conductive material having a needle-like shape, even if the content is small, the conductive material having a needle-like shape is easily connected to each other, so that the area of ​​the conductive part formed in the water adsorption film is easily expanded. In addition, the needle-like tip part of the conductive material having a needle-like shape protrudes from the water adsorption film, and the tip part acts like an antenna, so that the conductivity of the water adsorption film is improved, an electric field is more easily formed on the water adsorbent, and more water is adsorbed on the water adsorbent, so that water can be collected more efficiently. The conductive material having an acicular morphology may be included as a filler.

[0025] The needle-shaped conductive material preferably has a needle-shaped portion having a size of 0.1 to 50 μm, and more preferably 10 to 50 μm. When the needle-shaped portions of the conductive material having the needle-like shape are 0.1 to 50 μm in size, the conductive materials are more likely to come into contact with each other, and when they are 10 to 50 μm in size, the probability of the conductive materials coming into contact with each other increases, making it easier to ensure conductivity. Examples of the conductive material having a needle-like shape include tetrapod-type zinc oxide crystals and needle-like conductive titanium oxide. Examples of commercially available products of the conductive material having the needle-like shape include tetrapod-shaped zinc oxide, Pana-Tetra (Amtec Corporation), and needle-shaped conductive titanium oxide, FT series (needle type) (Ichihara Sangyo Co., Ltd.).

[0026] The content of the conductive material having an acicular shape in the water adsorption film is preferably 15 to 45 mass %, more preferably 30 to 45 mass %, and even more preferably 37.5 to 43 mass %, based on the mass of the water adsorption film.

[0027] -Organic matter- The water adsorption film may contain resins, organic polymers, and other organic substances other than those mentioned above, so long as they do not contradict the object of the present invention. There are no particular limitations on the resin that can be contained in the water adsorption film, so long as it does not contradict the object of the present invention. The organic polymer that can be contained in the water adsorption film is not particularly limited as long as it does not contradict the object of the present invention. There are no particular limitations on other organic substances that can be contained in the water adsorption film, so long as they do not contradict the object of the present invention.

[0028] The organic matter that can be contained in the water adsorption film may be in the form of a powder, and the shape of the organic matter is basically spherical, but may also be flaky or needle-like. The organic material that can be contained in the water adsorption film may be contained as a filler.

[0029] -Inorganic substances- The water adsorption film may contain minerals, inorganic polymers, and other inorganic substances other than those mentioned above, so long as they do not contradict the object of the present invention. There are no particular limitations on the ores that can be contained in the water adsorption film, so long as they do not contradict the object of the present invention. There are no particular limitations on the inorganic polymer that can be contained in the water adsorption film, so long as it does not contradict the object of the present invention. Other inorganic substances that can be contained in the water adsorption film are not particularly limited as long as they do not contradict the object of the present invention, and examples thereof include silica, mica, boron nitride, zinc oxide, titanium oxide, barium titanate, lead zirconate titanate, zinc oxide, silica, calcium carbonate, carbon materials (e.g., carbon black, carbon nanotubes, carbon fiber, fullerene structure-containing compounds, graphene, etc.), iron oxide, mica, clay minerals, synthetic hydrotalcite, metals, etc. The inorganic material that can be contained in the water adsorption film may be in the form of a powder, and the shape of the inorganic material is basically spherical, but may also be scaly or needle-like. The inorganic substance that can be contained in the water adsorption film may be contained as a filler.

[0030] The method for forming the water adsorption film is not particularly limited and may be appropriately selected depending on the purpose. Examples of the method include a method in which a tape containing a material that will become a water adsorption film is attached to the electrode, or a method in which a material that will become a water adsorption film is applied to the electrode by a spray coating method, a blade coating method, a roll coating method, a dipping coating method, a die coating method, or the like, and then the electrode is dried and baked. The thickness of the water adsorption film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 50 μm to 250 μm.

[0031] The water adsorption film is preferably an aggregated solidification body. The method for producing the agglomerated solidification body is not particularly limited as long as it does not prevent the water adsorption film from having water repellency, and the material or composition that will become the water adsorption film on the electrode may be dried, fired, or pressed with a roller or the like to form the agglomerated solidification body. When the water adsorption film is an aggregated solidification body, the surface of the water adsorption film becomes smooth, a fine uneven structure is formed, and the static contact angle on the water adsorption film tends to become large, so that the wettability of the water adsorption film becomes lower, thereby enhancing the effects of the present invention.

[0032] <Electrode> Since the water adsorbent has the electrodes, a potential difference can be generated between the charged water in the air and the water adsorbent, thereby generating a driving force for the charged water in the air to be adsorbed by the water adsorbent. The electrode may be in direct contact with ground (GND) or may be connected to ground (GND) via a wire to ensure a potential difference between the charged water in the air and the electrode. When an electric field generating device is used, the potential difference may be ensured by matching the reference potential of the device with the potential of the electrode. The electric field generating device may be of any type as long as it can generate a potential difference, and may be, for example, a charging gun.

[0033] The material contained in the electrode is not particularly limited as long as it has electrical conductivity, and may include organic substances, inorganic substances, metals, ores, polymers, etc., but it is preferable for the material to contain a metal, and it is more preferable for the material to contain a metal with high electrical conductivity.

[0034] There are no particular limitations on the organic material that can be contained in the electrode, so long as it does not contradict the object of the present invention. There are no particular limitations on the resin that can be contained in the electrode as long as it does not contradict the object of the present invention. There are no particular limitations on the inorganic substances that can be contained in the electrodes, so long as they do not contradict the object of the present invention. The metal that can be contained in the electrode is not particularly limited as long as it is conductive and does not contradict the object of the present invention, and examples thereof include aluminum, copper, and oxides thereof. From the viewpoints of cost, weight, and durability, aluminum is preferred. There are no particular limitations on the ores that can be contained in the electrodes, so long as they do not contradict the object of the present invention. The polymer that can be contained in the electrode is not particularly limited as long as it does not contradict the object of the present invention.

[0035] The shape of the electrode is not particularly limited as long as it exhibits the effects of the present invention, and may be in the form of a plate, a mesh, a line, a film, a point, a dot, or the like. The hardness of the electrode is not particularly limited as long as it is conductive, and may be highly flexible or highly rigid, and may be a flexible thin film or a highly rigid metal film. The thickness of the electrode is preferably from 1 to 200 μm, and more preferably from 10 to 100 μm. The surface roughness of the electrode is not particularly limited as long as it has electrical conductivity, but it is preferably Ra 0.1 to 0.5.

[0036] <Other materials> The water adsorbent may have a substrate as another member. The material of the substrate is not particularly limited as long as the electrodes and the water adsorption film can be formed thereon, and may be an organic or inorganic material, or may contain minerals, polymers, or the like.

[0037] The organic material that can be contained in the base material is not particularly limited as long as it does not contradict the object of the present invention, and examples thereof include resins. There are no particular limitations on the resin that can be contained in the base material, so long as it does not contradict the object of the present invention. There are no particular limitations on the inorganic substances that can be contained in the base material, so long as they do not contradict the object of the present invention. There are no particular limitations on the ores that can be contained in the base material, so long as they do not contradict the object of the present invention. The polymer that can be contained in the base material is not particularly limited as long as it does not contradict the object of the present invention. From the viewpoints of weight and durability, the substrate preferably includes a PET film or the like.

[0038] The hardness of the substrate may be high flexibility or high rigidity. The substrate may be a flexible thin film or a highly rigid metal film. The substrate may be conductive, and when the substrate is conductive, the substrate may be an electrode other than the electrode. In that case, in order to ensure a potential difference with the charged water in the air, the substrate may be directly contacted with the ground (GND) or connected to the ground (GND) by a wire, as in the case of the electrode. When a device capable of forming an electric field is used, the potential difference may be ensured by matching the reference potential of the device with the potential of the substrate. There is no particular limitation on the thickness of the substrate as long as it does not contradict the object of the present invention. The surface roughness of the substrate is not particularly limited as long as it does not interfere with the object of the present invention.

[0039] (Water collection device) The water collection device of the present invention comprises: The water adsorbent; a water recovery body that recovers the water adsorbed by the water adsorbent; A water collection device having the following structure. The water adsorbent in the water collecting device of the present invention is the same as the water adsorbent of the present invention described above, and the water adsorbent of the water collecting device of the present invention adsorbs water in the air. According to the water collecting device of the present invention, it is possible to reduce an increase in the weight of the water adsorbent while maintaining the amount of water that can be collected. Furthermore, the water collection device of the present invention may further include other members and / or devices as necessary.

[0040] <Water collection body> The water recovery body in the water collecting device of the present invention is not particularly limited as long as it can recover water, and the shape of the water recovery body may be a container, a plate, or the like. The material of the water recovery body is not particularly limited as long as it does not contradict the object of the present invention, and for example, materials containing resin, metal, etc. can be used.

[0041] -Recovered water- In the water collecting device of the present invention, the water adsorbed by the water adsorbent may be collected by the water recovery body. The water to be collected by the water recovery body is not particularly limited as long as it contains water. For example, the water may include water droplets that have fallen due to gravity and microdroplets that have split off from the charged water droplets that have reached the Rayleigh limit.

[0042] In this specification and the like, the term "amount of collected water" refers to the total amount of water adsorbed by the water adsorbent and the amount of water recovered by the water recovery body.

[0043] <Other components and / or equipment> The water collecting device of the present invention may include, as other members, a member that serves as a support for the water adsorbent and / or the water recovery body. The member for supporting the water adsorbent and / or the water recovery body is not particularly limited as long as it does not contradict the object of the present invention, and examples thereof include a stand. The water collection device of the present invention may include a device for charging the water and / or a device for creating an electric field, such as, for example, a charging gun.

[0044] (Water collection method) The water collection method of the present invention comprises the steps of: A method for collecting water from air, comprising the steps of: forming water droplets on a water adsorbent having an electrode and a water adsorption film; The water collection method is characterized in that the water adsorption film has water repellency. The water adsorbent in the water collection method of the present invention is the same as the water adsorbent of the present invention described above. The water collection method may further include other methods as necessary.

[0045] The water collection method of the present invention is a method for collecting water in the air, and can recover water that has been adsorbed onto the water adsorbent and separated therefrom, and can also recover water that has been split off from the water adsorbed onto the water adsorbent. The water split off from the water adsorbed on the water adsorbent may include minute water droplets split off from the charged water droplets that have reached the Rayleigh limit. In addition, the terms "airborne water," "water droplets," "charged water droplets," and "microdroplets" in the water collection method of the present invention are the same as those explained above.

[0046] According to the water collection method of the present invention, it is possible to reduce the weight increase of the water adsorbent while maintaining the amount of water that can be collected.

[0047] <Other methods> The water collection method of the present invention may include a method of charging the water and / or forming an electric field. Such a method may include, for example, a method of charging the water and / or forming an electric field using a device for charging the water and / or a device for forming an electric field. Such a device may include, for example, a charging gun.

[0048] The present invention will now be described with reference to FIGS. In addition, in each drawing, the same components are denoted by the same reference numerals, and duplicated explanations may be omitted. Furthermore, the number, position, shape, etc. of the following components are not limited to these embodiments, and may be the number, position, shape, etc. that are preferable for implementing the present invention.

[0049] FIG. 1 is a schematic diagram of an example of a water adsorbent according to an embodiment of the present invention. A water adsorbent 10 in FIG. 1 has an electrode 12 on a substrate 13 , and a water adsorbing film 11 on the electrode 12 .

[0050] FIG. 2 is a schematic diagram of an example of a water collection device according to an embodiment of the present invention. The water collecting device 1 in FIG. 2 is configured such that a water adsorbent 10 is suspended from a support 21, and a water recovery body 20 is installed thereon.

[0051] FIG. 3 is a schematic diagram showing how an electric field is formed in an example of a water collection device according to an embodiment of the present invention. The water collection device 1 in Fig. 3 has a water adsorbent 10 suspended from a support 21 and a water recovery body 20 installed thereon. A charge is applied from a charging gun 40 connected to an amplifier controller 50 to mist 70 ejected from a mist-like water generator 30, thereby charging the mist 70. By connecting the charging gun 40 and the water adsorbent 10 to a ground 60, a potential difference is created between the space in which the mist 70 exists and the water adsorbent, and an electric field 80 is formed.

[0052] FIG. 4 is a schematic diagram illustrating a state in which mist is generated and water is collected in an example of a water collecting device according to an embodiment of the present invention. In FIG. 4, similarly to FIG. 3, the mist 70 is charged by the charging gun 40, and an electric field 80 is formed between the space in which the mist 70 exists and the water adsorbent 10. Since the water adsorbent 10 has an electrode, a driving force is applied to the mist 70 to adsorb it to the water adsorbent 10. Since the water adsorbent 10 has a water-repellent water adsorption film 11, water droplets 90 smaller in size than when a water adsorption film without water repellency is used are formed on the surface of the water adsorbent 10. When the amount of charge that the water droplets can have reaches a maximum value, minute water droplets 91 split off from the water droplets 90 and are collected by the water recovery body 20. In addition, water 93 that has fallen off the water adsorbent 10 is also collected by the water recovery body 20.

[0053] FIG. 5 is a schematic diagram illustrating a state in which mist is generated and water is collected in an example of a water collecting device not according to the present invention. 5, similarly to FIG. 3, an electric charge is applied to the mist 70 by the charging gun 40, and an electric field 80 is formed between the space in which the mist 70 exists and the water adsorbent. Since the water adsorbent 14 has an electrode, a driving force is applied to the mist 70 to adsorb it to the water adsorbent 14, and water 92 is adsorbed thereto. However, since the water adsorbent 14 does not have a water adsorption film having water repellency, the amount of adsorbed water on the surface of the water adsorbent 14 increases and cannot be maintained by surface tension, and water 93 that has fallen off the water adsorbent 14 is collected by the water recovery body 20. EXAMPLES

[0054] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0055] Example 1 <Preparation of water adsorbent 1> A composite material (Alpet (model number 100-30), PANAC Corporation) made by bonding aluminum foil (thickness 30 μm) and polyester film (thickness 100 μm) was prepared as the electrode and substrate in the water collection device (substrate: polyester film, electrode: aluminum foil). A fluororesin PTFE tape (model number Scotch 5480, manufactured by Sumitomo 3M Limited) was attached onto the aluminum foil of this composite material as a water adsorption film, and then a SUS roller was pressed against the tape at a surface pressure of 5 MPa and rotated 5 to 10 times (vanishing process) to make the surface of the fluororesin tape into an aggregated solidified body and smooth, thereby producing water adsorbent 1.

[0056] [Static contact angle measurement] The static contact angle of a water droplet on the surface opposite to the substrate of the water adsorbent 1 prepared above (the water adsorbent film surface in the case of the water adsorbent 1) was measured using a contact angle measuring device (DropMaster500, Kyowa Interface Science Co., Ltd.) under the following measurement conditions. The results are shown in Table 1. <Measurement conditions> Mode:Static contact angle measurement mode Water: Ion-exchanged water Droplet volume: 1 [μL]

[0057] <Preparation of water collection device 1> The water adsorbent 1 was hung on a stand as shown in Figure 2 so that the substrate side of the water adsorbent 1 faced the stand serving as a support, and an acrylic plate (25 cm x 25 cm) serving as a water collection body was placed below the water adsorbent 1 at a position 5 cm from its bottom end, thereby preparing a water collection device 1.

[0058] <Formation of an electric field on a water collection device> As shown in Figure 3, an ultrasonic humidifier (DEWDROP-L, maximum humidification rate 320 ml / h, Three-Up Co., Ltd.) was installed as a device for generating water in the air at a horizontal distance of 15 cm from the surface of the suspended water adsorbent 1 to the center of the mist nozzle of the humidifier, and the height of the lower end of the suspended water adsorbent 1 and the mist nozzle of the ultrasonic humidifier were matched. In addition, a corona charging gun (GC90P, Green Techno Co., Ltd.) was installed opposite the water adsorbent 1, sandwiching an acrylic plate, and the horizontal distance from the center of the mist nozzle of the ultrasonic humidifier to the tip of the corona charging gun was 5 cm and the height was 5 cm. The aluminum foil part of the water adsorbent 1, the corona charging gun, and the ultrasonic humidifier were connected to ground (GND). In addition, an amplifier controller (GT series: GTC, Green Techno Co., Ltd.) was connected to the corona charging gun. While continuing to spray mist from the ultrasonic humidifier so that the mist hits the water adsorption film of the water adsorbent 1, an electric field was formed between the corona charging gun and the water adsorbent 1 under the electric field formation conditions described below, and the mist sprayed from the ultrasonic humidifier was positively charged. [Electric field formation conditions] Applied voltage: +25kV ·Current: 10μA ·Irradiation area: 12cm x 18cm

[0059] The electric field was continued to be formed under the above conditions, and the weight of water adsorbed in the water adsorbent 1 was measured after 10 minutes, 30 minutes, and 60 minutes had passed. The change over time is shown in FIG. In addition, the weight of water recovered on the acrylic plate 60 minutes after application of an electric field to the water adsorbent 1 was measured.

[0060] Example 2 <Preparation of water adsorbent 2> A fluororesin PFA tape (model number AFA113A-10X50, Chukoh Chemical Industry Co., Ltd.) was attached as a water adsorption film onto the aluminum foil of the composite material of aluminum foil and polyester film used in Example 1 to prepare a water adsorbent 2. The static contact angle of a water droplet was measured for the produced water adsorbent 2 in the same manner as in Example 1. The results are shown in Table 1.

[0061] In the same manner as in Example 1, a water collector 2 was produced using a water adsorbent 2 . Similarly to Example 1, an electric field was formed between the corona charging gun and the water adsorbent 2, and the weight of water adsorbed by the water adsorbent 2 was measured after 10 minutes, 30 minutes, and 60 minutes had elapsed. This change over time is shown in FIG. In addition, the weight of water recovered on the acrylic plate 60 minutes after application of an electric field to the water adsorbent 2 was measured.

[0062] Example 3 <Preparation of Water Adsorbent 3> A nanosilica coating agent (Glaco Mirror Coat 0, Soft99 Corporation) was spray-coated once as a water adsorption film on the aluminum foil of the same aluminum foil and polyester film composite material used in Example 1, and then dried at 25°C and a relative humidity of 45% for 24 hours to produce water adsorbent 3 having an aggregated solidified body of nanosilica with a fine uneven structure. The static contact angle of a water droplet was measured for the produced water adsorbent 3 in the same manner as in Example 1. The results are shown in Table 1.

[0063] In the same manner as in Example 1, a water collector 3 was produced using the water adsorbent 3 . Similarly to Example 1, an electric field was formed between the corona charging gun and the water adsorbent 3, and the weight of water adsorbed by the water adsorbent 3 was measured after 10 minutes, 30 minutes, and 60 minutes had elapsed. This change over time is shown in FIG. In addition, the weight of water recovered on the acrylic plate 60 minutes after application of an electric field to the water adsorbent 3 was measured.

[0064] Example 4 <Preparation of Water Adsorbent 4> A silicone rubber (model number KE-1353, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to a thickness of 100 μm as a water adsorption film on the aluminum foil of the composite material of aluminum foil and polyester film, which was the same as that used in Example 1, and baked at 120° C. for 30 minutes to produce a water adsorbent 4 having an aggregated solidified body of silicone rubber. The static contact angle of a water droplet was measured for the produced water adsorbent 4 in the same manner as in Example 1. The results are shown in Table 1.

[0065] In the same manner as in Example 1, a water collector 4 was produced using a water adsorbent 4 . Similarly to Example 1, an electric field was formed between the corona charging gun and the water adsorbent 4, and the weight of water adsorbed on the water adsorbent 4 was measured after 10 minutes, 30 minutes, and 60 minutes had elapsed. This change over time is shown in FIG. In addition, the weight of water recovered on the acrylic plate 60 minutes after application of an electric field to the water adsorbent 4 was measured.

[0066] Example 5 <Preparation of Water Adsorbent 5> On the aluminum foil of the same composite material of aluminum foil and polyester film used in Example 1, 150 g (100 parts by mass) of silicone rubber (model number KE-1353, Shin-Etsu Chemical Co., Ltd.) as a water adsorption film was added to 112.5 g (75 parts by mass) of Pana-Tetra (model number WZ05B1, Amtec Corporation) as a conductive material having a needle-like shape, and the mixture was applied to a thickness of 100 μm and baked at 120° C. for 30 minutes to produce water adsorbent 5 having an aggregated solidified body of silicone rubber and Pana-Tetra. The static contact angle of a water droplet was measured for the produced water adsorbent 5 in the same manner as in Example 1. The results are shown in Table 1.

[0067] In the same manner as in Example 1, a water collector 5 was produced using the water adsorbent 5 . Similarly to Example 1, an electric field was formed between the corona charging gun and the water adsorbent 5, and the weight of water adsorbed by the water adsorbent 5 was measured after 10 minutes, 30 minutes, and 60 minutes had elapsed. This change over time is shown in FIG. In addition, the weight of water recovered on the acrylic plate 60 minutes after application of an electric field to the water adsorbent 5 was also measured.

[0068] Comparative Example 1 <Preparation of Water Adsorbent 6> The same composite material of aluminum foil and polyester film (Alpet (model number 100-30), Panac Corporation) used in Example 1 was used as the water adsorbent 6. For the water adsorbent 6, the static contact angle of a water droplet on the aluminum foil was measured in the same manner as in Example 1. The results are shown in Table 1.

[0069] In the same manner as in Example 1, a water collector 6 was produced using a water adsorbent 6 . Similarly to Example 1, an electric field was formed between the corona charging gun and the water adsorbent 6, and the weight of water adsorbed by the water adsorbent 6 was measured after 10 minutes, 30 minutes, and 60 minutes had elapsed. This change over time is shown in FIG. In addition, the weight of water recovered on the acrylic plate 60 minutes after application of an electric field to the water adsorbent 6 was measured.

[0070] Comparative Example 2 <Preparation of Water Adsorbent 7> The composite material was the same as that used in Example 1, and was made of aluminum foil and polyester film. A fluororesin PTFE tape (model number Scotch 5480, manufactured by Sumitomo 3M Limited) was simply attached as a water adsorption film to the aluminum foil. This was used as water adsorbent 7. The static contact angle of a water droplet was measured for the produced water adsorbent 7 in the same manner as in Example 1. The results are shown in Table 1.

[0071] In the same manner as in Example 1, a water collector 7 was produced using the water adsorbent 7. Similarly to Example 1, an electric field was formed between the corona charging gun and the water adsorbent 7, and the weight of water adsorbed by the water adsorbent 7 was measured after 10 minutes, 30 minutes, and 60 minutes had elapsed. This change over time is shown in FIG. In addition, the weight of water recovered on the acrylic plate 60 minutes after application of an electric field to the water adsorbent 7 was measured.

[0072] [Table 1]

[0073] In the water adsorbents of Examples 1 to 5, the static contact angle of the water adsorption film to water was 90° or more, and all of them had water repellency. The water adsorbent of Comparative Example 1 did not have a water adsorption film, and the static contact angle of water on the surface of the aluminum foil serving as the electrode was 10° or less. The water adsorbent of Comparative Example 2 had a water adsorption film, but the static contact angle with water was 85°, which was less than 90°, and therefore did not have water repellency.

[0074] As shown in FIG. 6 , the weights of water adsorbed to the water adsorbents of Examples 1 to 5 and Comparative Examples 1 and 2 10 minutes, 30 minutes, and 60 minutes after application of an electric field were less in Examples 1 to 5 than in Comparative Examples 1 and 2 at any elapsed time. In addition, the amount of water collected 60 minutes after application of an electric field to the water adsorbents of Examples 1 to 5 and Comparative Examples 1 and 2, i.e., the sum of the weight of water adsorbed in the water adsorbent and the weight of water recovered in the acrylic plate, which is the water recovery body, was almost the same among Examples 1 to 5 and Comparative Examples 1 and 2.

[0075] From the above, it was demonstrated that a water adsorbent satisfying the configuration of the present invention can reduce the weight increase of the water adsorbent while maintaining the amount of water that can be collected.

[0076] For example, aspects of the present invention are as follows. <1> A water adsorbent that adsorbs water in the air, the water adsorbent having an electrode and a water adsorption film, the water adsorption film having water repellency. <2> The water adsorption film is an aggregated solidification body. <1> The water adsorbent according to claim 1. <3> The water adsorption film includes a conductive material having a needle-like shape. <1> or <2> The water adsorbent according to claim 1. <4> The conductive material having a needle-shaped morphology is a tetrapod-type zinc oxide crystal and / or a needle-shaped conductive titanium oxide. <3> The water adsorbent according to claim 1. <5> The water adsorption film contains nanosilica, fluorine-based resin, or silicone resin. <1> , <2> , <3> , and <4> 2. The water adsorbent according to claim 1 . <6> The above <1> , <2> , <3> , <4> , and <5> and a water recovery body that recovers the water adsorbed by the water adsorbent. <7> A method for collecting water in the air, comprising forming water droplets on a water adsorbent having an electrode and a water adsorption film, the water adsorption film being water repellent. <8> The water droplets include charged water droplets having an electric charge, and minute water droplets split off from the charged water droplets are collected. <7> The water collection method according to claim 1.

[0077] the above <1> from <5> Any of the water adsorbents <6> The water collection device <7> from <8> According to any one of the water collection methods described above, the conventional problems can be solved and the object of the present invention can be achieved. [Explanation of symbols]

[0078] 1 Water collection device 10 Water-adsorbent (water-repellent) 11 Water adsorption membrane 12 electrodes 13 Base material 14 Water-adsorbent (not water-repellent) 20 Water collector 21 Support 30 Mist Water Generator 40 Charging gun 50 Amp Controller 60 Grand 70 fog 80 Electric Field 90 water droplets 91 Minute water droplets 92 water 93 Water that has fallen off the water adsorbent [Prior art documents] [Non-patent literature]

[0079] [Non-Patent Document 1] Maher Damak et al.,Electrostatically driven fog collection using space charge injection, Damak and Varanasi, Sci. Adv. 2018;4: eaao5323 8 June 2018

Claims

1. A water adsorbent that adsorbs water in the air, the water adsorbent has an electrode and a water adsorption film, The water adsorption film is characterized in that it has water repellency. Water adsorbent.

2. 2. The water adsorbent according to claim 1, wherein the water adsorption film is an aggregated solidified body.

3. The water adsorbent according to claim 1 , wherein the water adsorption film comprises a conductive material having a needle-like shape.

4. 4. The water adsorbent according to claim 3, wherein the conductive material having an acicular shape is tetrapod-type zinc oxide crystals and / or acicular conductive titanium oxide.

5. The water adsorbent according to claim 1 , wherein the water adsorption film contains nanosilica, a fluorine-based resin, or a silicone resin.

6. A water adsorbent according to any one of claims 1 to 4, a water recovery body that recovers the water adsorbed by the water adsorbent; A water collection device having:

7. A method for collecting water from air, comprising the steps of: forming water droplets on a water adsorbent having an electrode and a water adsorption film; The water collection method, wherein the water adsorption film has water repellency.

8. The water droplets include charged water droplets having an electric charge, The method for collecting water according to claim 7, further comprising collecting minute water droplets which are split off from the charged water droplets.

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