Electrode substrate and liquid detection sensor

Abstract

An electrode substrate (10) according to the present disclosure is characterized by comprising: a base material (20) that has a first surface (21) and a second surface (22); and a positive electrode (30) and a negative electrode (40) that are disposed separated from each other on the first surface (21) or the second surface (22) of the base material (20), wherein a liquid permeates between the positive electrode (30) and the negative electrode (40) to discharge electricity, and the distance between the positive electrode (30) and the negative electrode (40) is 0.1–100 mm. In addition, by providing a transmission unit (70) or a notification unit (80) that is electrically connected to the electrode substrate (10), the electrode substrate (10) may constitute a liquid detection sensor (100) that is capable of detecting adhesion of a liquid.

Description

Electrode substrate and liquid detection sensor

[0001] This disclosure relates to an electrode substrate and a liquid detection sensor.

[0002] Liquid detection sensors containing electrode substrates are known. The electrode substrate discharges when liquid permeates between the positive and negative electrodes. The electrode substrate, together with the liquid, constitutes a metal-air battery. Liquid detection sensors are applied to buildings such as underground facilities and factories. By detecting the discharge of the electrode substrate, the liquid detection sensor detects the occurrence of liquid leakage and flooding in the application area.

[0003] JP2021040907A discloses a liquid detection sensor including an electrode substrate. The liquid detection sensor of Patent Document 1 includes a housing and an electrode substrate disposed within the housing. The electrode substrate includes a positive electrode and a negative electrode, and a separator disposed between the positive electrode and the negative electrode. In JP2021040907A, the electrode substrate is an electrode substrate that discharges due to an oxidation-reduction reaction between the positive electrode and the negative electrode caused by a liquid that has permeated the separator.

[0004] The electrode substrate of JP2021040907A discharges when liquid penetrates into the separator. Discharge does not begin until the liquid adhering to the separator penetrates into the separator. In the electrode substrate of JP2021040907A, there is a time lag between the adhesion of liquid to the separator and the start of discharge.

[0005] In view of the above circumstances, this disclosure aims to shorten the time from the adhesion of liquid to the start of discharge in an electrode substrate.

[0006] The gist of the structure of this disclosure is as follows:

[0007] [1] An electrode substrate comprising a substrate having a first surface and a second surface, and a positive electrode and a negative electrode disposed apart from each other on the first surface or the second surface of the substrate, wherein a discharge occurs when a liquid penetrates between the positive electrode and the negative electrode.

[0008] [2] The electrode substrate of [1] which constitutes the discharge section of the metal-air battery.

[0009] [3] An electrode substrate for a metal-air battery, comprising a substrate having a first surface and a second surface, and a positive electrode and a negative electrode disposed apart from each other on the first surface or the second surface of the substrate, wherein discharge occurs when a liquid penetrates between the positive electrode and the negative electrode.

[0010] [4] A flexible electrode substrate, one of the [1] to [3].

[0011] [5] The positive electrode comprises a metal layer and a conductive layer, wherein the metal layer is located between the substrate and the conductive layer, and is an electrode substrate of any of [1] to [4].

[0012] [6] The electrode substrate of [5], wherein the thickness of the conductive layer is greater than or equal to the thickness of the metal layer, and the thickness ratio of the metal layer to the conductive layer is 1:1 to 1:20.

[0013] [7] The electrode substrate according to [5], wherein the thickness of the conductive layer is greater than or equal to the thickness of the metal layer, and the thickness ratio of the metal layer to the conductive layer is 1:1 to 1:4.

[0014] [8] The electrode substrate of [5], wherein the thickness of the conductive layer is greater than or equal to the thickness of the metal layer, and the thickness ratio of the metal layer to the conductive layer is 1:1 to 1:2.

[0015] [9] The electrode substrate of [5] wherein the thickness of the conductive layer is smaller than the thickness of the metal layer.

[0016]

[10] An electrode substrate of any of [5] to [9], wherein the thickness of the conductive layer is 80 μm or less.

[0017]

[11] The metal layer is an electrode substrate of any of [5] to

[10] , including stainless steel.

[0018]

[12] The metal layer is an electrode substrate of any of [5] to

[10] , comprising aluminum.

[0019]

[13] An electrode substrate of any of [1] to

[12] , wherein the thickness of the positive electrode is 20 μm or more and 200 μm or less.

[0020]

[14] The negative electrode is an electrode substrate from any of [1] to

[13] , comprising a metal having a higher ionization tendency than zinc.

[0021]

[15] An electrode substrate of any of [1] to

[14] , wherein the distance between the positive electrode and the negative electrode is 0.1 mm or more and 100 mm or less.

[0022]

[16] The positive electrode and the negative electrode are each electrode substrates of any of [1] to

[15] , extending in the longitudinal direction of the electrode substrate and moving away from each other in the width direction perpendicular to the longitudinal direction.

[0023]

[17] A liquid detection sensor comprising one of the electrode substrates [1] to

[16] and a transmitting unit electrically connected to the electrode substrate.

[0024]

[18] A liquid detection sensor comprising an electrode substrate of any of [1] to

[16] and a notification unit electrically connected to the electrode substrate.

[0025] The electrode substrate according to this disclosure can shorten the time from liquid adhesion to the start of discharge.

[0026] This is a cross-sectional view of the electrode substrate. This is a schematic diagram of the electrode substrate. This is a schematic diagram of the electrode substrate in elongated form. This is a schematic diagram of the liquid detection sensor. This is a schematic diagram of the liquid detection sensor. This is an explanatory diagram of an embodiment of the liquid detection sensor.

[0027] Embodiments of the electrode substrate and liquid detection sensor according to the present invention will be described with reference to the drawings. Figure 1 is a cross-sectional view of the electrode substrate, Figure 2 is a schematic diagram illustrating an embodiment of the electrode substrate of Figure 1, Figure 3 is a schematic diagram of the electrode substrate in elongated form, Figures 4 and 5 are schematic diagrams of the liquid detection sensor, and Figure 6 is an explanatory diagram of an embodiment of the liquid detection sensor.

[0028] Directions common to multiple drawings are indicated by arrows with a common reference numeral in each drawing. In each illustrated direction, the tip of the arrow is the first side, and the opposite side, i.e., the base of the arrow, is the second side. In Figure 1, the first side in the direction perpendicular to the drawing is indicated by a symbol of a circle with a dot inside. The second side in the direction perpendicular to the drawing is indicated by a symbol of a circle with an X inside.

[0029] Figure 1 shows a cross-sectional view of the electrode substrate 10. Figure 2 is a schematic diagram of the electrode substrate 10 of Figure 1. The electrode substrate 10 of Figure 1 includes a base material 20 having a first surface 21 and a second surface 22, and a positive electrode 30 and a negative electrode 40 disposed on the first surface 21 or the second surface 22 of the base material 20. The positive electrode 30 and the negative electrode 40 are arranged on the same surface of the base material 20. The electrode substrate 10 discharges when liquid penetrates between the positive electrode 30 and the negative electrode 40, as will be described in detail later. When the liquid penetrates between the positive electrode 30 and the negative electrode 40, the electrode substrate 10, together with the liquid, constitutes a primary battery. In particular, as will be described below, in the illustrated electrode substrate 10, air is used as the active material of the positive electrode 30. Therefore, when the liquid penetrates between the positive electrode 30 and the negative electrode 40, the electrode substrate 10 constitutes a metal-air battery. The electrode substrate 10 of Figures 1 and 2 are components of a primary battery. The liquid that permeates between the positive electrode 30 and the negative electrode 40 functions as the electrolyte of the primary battery. The electrode substrate 10 may constitute the discharge section of a metal-air battery. The electrode substrate that constitutes the discharge section of a metal-air battery may also be described as the electrode substrate of a metal-air battery.

[0030] The liquid that permeates between the positive electrode 30 and the negative electrode 40 may contain water molecules, for example, water or an aqueous solution. The aqueous solution that permeates between the positive electrode 30 and the negative electrode 40 may contain water molecules, or it may be saline solution. In the electrode substrate 10 of Figure 1, the positive electrode 30 and the negative electrode 40 are arranged on the first surface 21 of the base material 20. In the base material 20 of Figure 1, the first surface 21 and the second surface 22 face each other in the first direction D1. In the electrode substrate 10 of Figure 1, the positive electrode 30 and the negative electrode 40 constitute the electrode portion 50. The positive electrode 30 and the negative electrode 40 are arranged apart from each other in a direction perpendicular to the first direction D1.

[0031] The illustrated electrode substrate 10 has a simple configuration in which the positive electrode 30 and the negative electrode 40 are held electrically separated on the same surface of the base material 20. Therefore, it is advantageous in reducing costs such as material costs and manufacturing costs, and can be provided at a low cost.

[0032] The electrode substrate 10 in Figure 1 may be applied to sanitary products such as diapers, bandages, and adhesive bandages. The electrode substrate 10 may also be applied to buildings such as underground facilities and factories. As will be described later, a liquid detection sensor 100 may be configured by combining the electrode substrate 10 with a transmitting unit 70 or a notification unit 80. The liquid detection sensor 100 may detect the occurrence of liquid leaks and flooding in the above-mentioned application targets. The liquid leak detected by the liquid detection sensor 100 may be a leak of liquid containing water molecules. The liquid leak detected by the liquid detection sensor 100 may also be a leak of water or an aqueous solution. The electrode substrate 10 may be bonded to the application target. The application target of the electrode substrate 10 may also be the object to which the electrode substrate 10 is attached.

[0033] The electrode substrate 10 may include a bonding layer 60 that joins the base material 20 and the electrode portion 50. The electrode substrate 10 in Figure 1 further includes a first bonding layer 61 that joins the positive electrode 30 and the base material 20, and a second bonding layer 62 that joins the negative electrode 40 and the base material 20, as the bonding layer 60 that joins the base material 20 and the electrode portion 50. One or more adhesives, glues, and double-sided tapes may be used for the bonding layer 60. In particular, it is preferable to use a glue for the bonding layer 60 from the viewpoint of durability. The glue may include a thermoplastic resin. The glue containing a thermoplastic resin may join the base material 20 and the electrode portion 50 when heated.

[0034] The electrode substrate 10 in Figures 1 and 2 is flexible. The electrode substrate 10 is flexible when all three of the following conditions (A), (B), and (C) are met. Note that the electrode substrate 10 may be removed from the paper tube when it is determined that the following condition (C) is met. (A) It can be wound on a 3-inch paper tube. (B) When the electrode substrate 10 wound on the paper tube is visually inspected, no cracks or breaks occur in the positive electrode 30. (C) When the electrode substrate 10 wound on the paper tube is visually inspected, no plastic deformation occurs in the negative electrode 40.

[0035] The electrode substrate 10 is flexible, allowing it to maintain a bent state. This allows the electrode substrate 10 to expand the shape of the adherend. The flexible electrode substrate 10 can be bonded to a curved adherend, for example. For example, the flexible electrode substrate 10 can be wrapped around a tube. The electrode substrate 10 wrapped around a tube can discharge due to liquid leaking from the tube. The flexible electrode substrate 10 can deform in accordance with changes in the shape of the adherend while maintaining a state that allows for stable discharge when liquid penetrates between the positive electrode 30 and the negative electrode 40. The flexible electrode substrate 10 can be bonded to deformable adherends such as cloth, paper, and nonwoven fabric, as an example. In order for the electrode substrate 10 to deform according to the shape of the adherend, at least the above condition (A) must be satisfied in the electrode substrate 10. The electrode substrate 10 may satisfy the above-described conditions (A) and (B), or conditions (A) and (C), so that it can deform in accordance with changes in the shape of the adherend while maintaining a state in which discharge is possible when liquid penetrates between the positive electrode 30 and the negative electrode 40.

[0036] The positive electrode 30 shown in Figures 1 and 2 includes a metal layer 31 and a conductive layer 32. The metal layer 31 is located between the substrate 20 and the conductive layer 32. The conductive layer 32 is coated on the metal layer 31. The metal layer 31 in Figure 1 has the function of supporting the conductive layer 32 and the function of being a current collector for the positive electrode 30. The metal contained in the metal layer 31 may include one or more of nickel (Ni), copper (Cu), silver (Ag), aluminum (Al), and stainless steel (SUS). By including one or more of these metals, the conductivity of the metal layer 31 can be improved, and the function of the positive electrode 30 as a current collector can be improved. Furthermore, the metal layer 31 preferably contains stainless steel from the viewpoint of strength for supporting the conductive layer 32, material cost, and rust suppression.

[0037] The conductive layer 32 includes air and a holding material for holding the air. The holding material is joined to the base material 20 by the first joining layer 61. As the material of the holding material, carbon black or the like having a large specific surface area is desirable. In the conductive layer 32, by increasing the specific surface area of the holding material, the volume of the air held by the holding material can be increased. By including a holding material such as carbon black, the electrode substrate 10 can increase the voltage during discharge per predetermined dimension in the longitudinal direction L of the unit length.

[0038] The conductive layer 32 may include a binder resin for dispersing the holding material. The conductive layer may be formed from an ink containing a holding material, a binder resin, and a solvent. The conductive layer 32 may be formed by drying the ink applied to the material forming the metal layer 31.

[0039] The positive electrode 30 shown in FIGS. 1 and 2 has flexibility. Also, the thickness of the positive electrode 30 in FIG. 1, that is, the total thickness of the metal layer 31 and the conductive layer 32 is preferably 20 μm or more and 200 μm or less. Note that the thicknesses of the electrode substrate in FIG. 10 and the components of the electrode substrate 10 are dimensions in the first direction D1. If the thickness of the positive electrode 30 is 20 μm or more, processing of the metal layer 31 or coating of the conductive layer 32 becomes easy. Also, if the thickness of the positive electrode 30 is 200 μm or less, the occurrence of cracks, breaks, etc. in the bent positive electrode 30 is suppressed. Thereby, the electrode substrate 10 can discharge stably even when installed in a bent state.

[0040] The thickness ratio of the metal layer 31 and the conductive layer 32 may be 1:1 to 1:20. If the thickness ratio of the metal layer 31 and the conductive layer 32 is 1:1 or more, the positive electrode including the conductive layer 32 can exhibit stable performance. However, from the viewpoint of further stably ensuring the adhesion between the metal layer 31 and the conductive layer 32, the thickness of the conductive layer 32 may be smaller than the thickness of the metal layer 3%. When the thickness of the conductive layer 32 is smaller than the thickness of the metal layer 31, the thickness of the conductive layer 32 may be 0.1 times or more, 0.5 times or more, or 0.7 times or more of the thickness of the metal layer 3%.

[0041] If the thickness ratio of the metal layer 31 to the conductive layer 32 is 1:20 or less, the metal layer 31 can sufficiently function as a current collector while maintaining flexibility. Note that the thickness ratio of the metal layer 31 to the conductive layer 32 being "1:1" means that the thickness of the conductive layer 32 is the same as that of the metal layer. Also, the thickness ratio of the metal layer 31 to the conductive layer 32 being "1:20" means that the thickness of the conductive layer 32 is 20.0 times that of the metal layer.

[0042] In particular, as shown in the result of Evaluation 1 of the following experiment, from the viewpoint of stably maintaining the shape of the positive electrode 30, the thickness ratio of the metal layer 31 to the conductive layer 32 is more preferably 1:1 to 1:4. Note that the thickness ratio of the metal layer 31 to the conductive layer 32 being "1:4" means that the thickness of the conductive layer 32 is 4.0 times that of the metal layer.

[0043] Further, as shown in the result of Evaluation 2 of the following experiment, from the viewpoint of stably ensuring the adhesion between the metal layer 31 and the conductive layer 32, the thickness ratio of the metal layer 31 to the conductive layer 32 is more preferably 1:1 to 1:2, and even more preferably 1:1. Note that the thickness ratio of the metal layer 31 to the conductive layer 32 being "1:2" means that the thickness of the conductive layer 32 is 2.0 times that of the metal layer.

[0044] In the positive electrode of the electrode substrate, pinholes or cracks may occur in the conductive layer formed on the metal layer. A pinhole is a recess formed on the surface of the conductive layer. The thickness of the conductive layer decreases at least in the portion where at least one of the pinholes and cracks occurs. When the thickness of the conductive layer decreases, the current due to the discharge of the electrode substrate may become unstable. The occurrence of at least one of the pinholes and cracks in the conductive layer is not preferable from the viewpoint of stabilizing the current. From the viewpoint of stabilizing the current, it is preferable that the conductive layer does not include pinholes or cracks having a size of 500 μm or more in a plan view, and more preferably does not include pinholes or cracks having a size of more than 200 μm and less than 500 μm in a plan view. The plan view of the conductive layer means an observation from the normal direction of the conductive layer.

[0045] From the viewpoint of reliably suppressing the occurrence of at least one of pinholes and cracks in the conductive layer 32, an upper limit may be set for the thickness of the conductive layer 32. Specifically, as shown in the results of Evaluation 2 of the experiment below, the thickness of the conductive layer 32 is preferably 80 μm or less. By setting the thickness of the conductive layer 32 to 80 μm or less, the occurrence of at least one of pinholes and cracks in the conductive layer 32 can be suppressed in the electrode substrate 10, and the current can be stabilized. From a similar viewpoint, the thickness of the conductive layer 32 may be 75 μm or less, 70 μm or less, or 55 μm or less.

[0046] From the viewpoint of stabilizing the operation of the positive electrode 30, a lower limit may be set for the thickness of the conductive layer 32. The thickness of the conductive layer 32 may be 5 μm or more, or 10 μm or more.

[0047] A thickness gauge is used to measure the thickness of the positive electrode 30 and the thickness of the metal layer 31. The maximum indication error of the thickness gauge shall be 3 μm or less. The thickness of the positive electrode 30 and the thickness of the metal layer 31 shall be the median value of measurements taken at five different locations using the thickness gauge. The thickness of the conductive layer 32 is calculated as the difference between the thickness of the positive electrode 30 and the thickness of the metal layer 31.

[0048] <<Experiment>> Samples 1 to 4 of the positive electrode were prepared using the following procedure. As the sheet for forming the metal layer, a stainless steel sheet (SUS316L) with a thickness of 10 μm was prepared, as described in the "Metal Layer Material" and "Metal Layer Thickness [μm]" columns of Table 1 below. An ink for forming the conductive layer was applied to one side of the sheet. A coating machine (Mitsui Electric Precision Co., Ltd. "Desktop Coater TC-3S type") was used for applying the ink. The ink for forming the conductive layer contained a solvent, a binder resin, and a retaining agent. The retaining agent was carbon black. The thickness of the ink applied to one side of the sheet differed among samples 1 to 4. Samples containing a metal layer and a conductive layer were prepared by drying the ink for 1 hour in an environment of 80°C. In samples 1 to 4, the thickness of the metal layer was 10 μm. In samples 1 to 4, the thickness of the conductive layer differed as follows. The thickness of each sample was measured using a thickness gauge (Mitutoyo Corporation "547-401") by the method described above. The thickness of the conductive layer was calculated from the measured sample thickness after the ink dried. Table 1 shows the ratio of the conductive layer thickness to the metal layer thickness for samples 1 to 4 in the "Thickness Ratio [-]" column. Sample 1 (conductive layer thickness): 20 μm Sample 2 (conductive layer thickness): 30 μm Sample 3 (conductive layer thickness): 40 μm Sample 4 (conductive layer thickness): 60 μm

[0049] Samples 5-9 of the positive electrode were prepared. Samples 5-9 were prepared using the same procedure as samples 1-4 described above, except for the composition of the sheet forming the metal layer. In samples 5-9, an aluminum sheet (AlIN30) with a thickness of 10 μm was used as the sheet forming the metal layer, as described in the "Metal Layer Material" and "Metal Layer Thickness [μm]" columns of Table 2 below. In samples 5-9, the thickness of the metal layer was 10 μm. In samples 5-9, the thickness of the conductive layer differed as follows. The thickness of the conductive layer was calculated after the ink dried. In Table 2, the ratio of the thickness of the conductive layer to the thickness of the metal layer in samples 5-9 is shown in the "Thickness Ratio [-]" column. Sample 5 (Conductive layer thickness): 20 μm Sample 6 (Conductive layer thickness): 35 μm Sample 7 (Conductive layer thickness): 50 μm Sample 8 (Conductive layer thickness): 75 μm Sample 9 (Conductive layer thickness): 90 μm

[0050] Samples 10-14 of the positive electrode were prepared. Samples 10-14 were prepared using the same procedure as samples 1-4 described above, except for the composition of the sheet forming the metal layer. In samples 10-14, a stainless steel sheet (SUS304) with a thickness of 30 μm was used as the sheet forming the metal layer, as described in the "Metal Layer Material" and "Metal Layer Thickness [μm]" columns of Table 3 below. In samples 10-14, the thickness of the metal layer was 30 μm. In samples 10-14, the thickness of the conductive layer differed as follows. The thickness of the conductive layer was calculated after the ink forming the conductive layer was dried as described above. In Table 3, the ratio of the thickness of the conductive layer to the thickness of the metal layer in samples 10-14 is shown in the "Thickness Ratio [-]" column. Sample 10 (conductive layer thickness): 20 μm Sample 11 (conductive layer thickness): 30 μm Sample 12 (conductive layer thickness): 40 μm Sample 13 (conductive layer thickness): 60 μm Sample 14 (conductive layer thickness): 80 μm

[0051] Samples 15-18 of the positive electrode were prepared. Samples 15-18 were prepared using the same procedure as samples 1-4 described above, except for the composition of the sheet forming the metal layer. For samples 15-18, an aluminum sheet (AlIN30) with a thickness of 30 μm was used as the sheet forming the metal layer, as described in the "Metal Layer Material" and "Metal Layer Thickness [μm]" columns of Table 4 below. In samples 15-18, the thickness of the metal layer was 30 μm. In samples 15-18, the thickness of the conductive layer differed as follows. The thickness of the conductive layer was calculated after the ink dried. In Table 4, the ratio of the thickness of the conductive layer to the thickness of the metal layer in samples 15-18 is shown in the "Thickness Ratio [-]" column. Sample 15 (Conductive layer thickness): 15 μm Sample 16 (Conductive layer thickness): 40 μm Sample 17 (Conductive layer thickness): 55 μm Sample 18 (Conductive layer thickness): 70 μm

[0052] <Evaluation 1> Each sample was placed on a flat mounting surface. The sample placed on the mounting surface had dimensions of 20 cm in the longitudinal direction. The sample placed on the mounting surface had dimensions of 11 cm in the width direction perpendicular to the longitudinal direction. Each sample on the mounting surface was placed so that the surface composed of the conductive layer faced away from the mounting surface. In this state, the presence or absence of warping of each sample was observed. The observation results for samples 1 to 4 are shown in the "Evaluation 1" column of Table 1 below. The observation results for samples 5 to 9 are shown in the "Evaluation 1" column of Table 2 below. The observation results for samples 10 to 14 are shown in the "Evaluation 1" column of Table 3 below. The observation results for samples 15 to 18 are shown in the "Evaluation 1" column of Table 4 below. The meaning of the entries in the "Evaluation 1" column is as follows: "AA": No warped parts were found in the sample. "A": The width dimension of the warped part of the sample was 40% or less of the total width of the sample. The distance between the curved portion of the sample and the mounting surface was 20 mm or less.

[0053] <Evaluation 2> The shape of the surface composed of the conductive layer of each sample was observed using a microscope (Keyence Corporation "Digital Microscope (VHS-950F)"). The microscope magnification was 50x. In plan view, the maximum dimension of the microscope's observation field was 7.4 mm. In plan view, the minimum dimension of the microscope's observation field was 5.5 mm. The observation results for samples 1 to 4 are shown in the "Evaluation 2" column of Table 1 below. The observation results for samples 5 to 9 are shown in the "Evaluation 2" column of Table 2 below. The observation results for samples 10 to 14 are shown in the "Evaluation 2" column of Table 3 below. The observation results for samples 15 to 18 are shown in the "Evaluation 2" column of Table 4 below. The meaning of the entries in the "Evaluation 2" column is as follows: "AA": No pinholes or cracks with dimensions of 200 μm or more were observed on the surface. "A": One to four pinholes with dimensions of 200 μm or more and less than 500 μm were observed on the surface.

[0054] <Evaluation 3> The peelability of the conductive layers from the metal layer was evaluated for the conductive layers of samples 10 to 14 in accordance with the provisions of JIS K 5600-5-6:1999. A grid pattern was formed on the conductive layers of samples 10 to 14. The surface of the conductive layer was brushed along the diagonals of the grid pattern. Adhesive tape ("Cellotape (registered trademark) CT405AP-24" manufactured by Nichiban Co., Ltd.) was bonded onto the grid pattern with the adhesive side facing outwards. The adhesive tape bonded to samples 10 to 14 was peeled off within 5 minutes of bonding. The state of the grid pattern was observed in the samples after the adhesive tape was removed. The observation results are shown in the "Evaluation 3" column of Table 3 below. The meaning of the entries in the "Evaluation 3" column is as follows: "0": This corresponds to classification 0 in the 6-stage classification test specified in JIS K 5600-5-6:1999. "1": The product was in the state of Classification 1 in the 6-level classification test specified in JIS K 5600-5-6:1999. "2": The product was in the state of Classification 2 in the 6-level classification test specified in JIS K 5600-5-6:1999. "4": The product was in the state of Classification 4 in the 6-level classification test specified in JIS K 5600-5-6:1999.

[0055]

[0056]

[0057]

[0058]

[0059] The negative electrode 40 may contain a metal. The metal contained in the negative electrode 40 may be one or more of the following: magnesium (Mg), aluminum (Al), lithium (Li), calcium (Ca), zinc (Zn), nickel (Ni), and cadmium (Cd). From the viewpoint of power generation efficiency, the metal contained in the negative electrode 40 is preferably a metal having an ionization tendency of zinc (Zn) or higher among the above-mentioned metals. Specifically, it is particularly preferable that the negative electrode 40 contains magnesium (Mg) and / or aluminum (Al) as a metal having an ionization tendency of zinc (Zn) or higher. Also, from the viewpoint of availability, it is particularly preferable that the metal contained in the negative electrode 40 contains magnesium and / or aluminum among metals having an ionization tendency of zinc (Zn) or higher. The negative electrode 40 may contain only one of the above-mentioned metals. The negative electrode 40 may contain an alloy of one of the above-mentioned metals with another metal. As an example of an alloy contained in the negative electrode 40, the negative electrode 40 may be an alloy of nickel (Ni) and cadmium (Cd).

[0060] The negative electrode 40 in Figure 1 is flexible. Furthermore, the thickness of the negative electrode 40 in Figure 1 is preferably between 10 μm and 200 μm. If the thickness of the negative electrode 40 is 10 μm or more, processing of the negative electrode 40 is easy or material costs can be kept low. Also, if the thickness of the negative electrode 40 is 200 μm or less, flexibility of the negative electrode 40 in a bent state is ensured. As a result, the electrode substrate 10 can discharge stably even when installed in a bent state.

[0061] Figure 2 shows a schematic diagram of the electrode substrate 10. The electrode substrate 10 in Figure 2 has a longitudinal direction L. The longitudinal direction L is perpendicular to the first direction D1. The positive electrode 30 and the negative electrode 40 each extend in the longitudinal direction L on the substrate 20. The positive electrode 30 and the negative electrode 40 are separated from each other in the width direction W, which is perpendicular to the longitudinal direction L. The width direction W is perpendicular to both the first direction D1 and the longitudinal direction L.

[0062] As described above, the electrode substrate 10 is flexible. This flexibility allows the liquid detection sensor 100 to be installed even on curved surfaces or complex shapes. Furthermore, the flexibility of the electrode substrate 10 allows it to remain coiled even when it is long, as shown in Figure 3. The electrode substrate 10 in Figure 3 is coiled around an axis parallel to the width direction W. Maintaining a long electrode substrate in a coiled state allows for storage in a spiral shape while minimizing storage space and reducing the risk of damage to the electrode substrate 10.

[0063] Furthermore, the electrode substrate 10 shown in Figure 2 may be cut from the long electrode substrate 10 shown in Figure 3. The electrode substrate 10 in Figure 2 may be obtained by cutting out a portion of the long electrode substrate 10 in the longitudinal direction L. The voltage during discharge of the electrode substrate 10 may increase by increasing the dimension of the electrode substrate 10 in the longitudinal direction L. The electrode substrate 10 may be cut from the long electrode substrate 10 according to the discharge voltage. The long electrode substrate 10 shown in Figure 3 is highly convenient when cutting to a desired length.

[0064] The positive electrode 30 and negative electrode 40, positioned on the first surface 21 or the second surface 22 of the substrate 20, are arranged to avoid unintended electrical connections. The distance between the positive electrode 30 and the negative electrode 40 is preferably 0.1 mm or more and 100 mm or less. In the electrode substrate 10 of Figures 1 and 2, the distance between the positive electrode 30 and the negative electrode 40 is 0.1 mm or more and 100 mm or less in the direction perpendicular to the first direction D1, including the longitudinal direction L and the width direction W. If the distance between the positive electrode 30 and the negative electrode 40 is 0.1 mm or more, unintended conductivity due to water droplets generated on at least one of the surfaces of the positive electrode 30 and the negative electrode 40 due to condensation, for example, can be avoided. If the distance between the positive electrode 30 and the negative electrode 40 is 100 mm or less, liquid can be detected according to a desired amount of leakage, for example. From a manufacturing standpoint, 0.5 mm or more is preferred, and from the viewpoint of installation flexibility, 50 mm or less is preferred.

[0065] The base material 20 can be made of any material as long as it can accommodate the positive electrode 30 and the negative electrode 40, and can be appropriately selected from nonwoven fabrics, polyurethane foams, plastic films, etc. Plastic films are preferred, and examples include polyethylene (PE), polypropylene (PP / OPP), polyvinyl chloride (PVC), polystyrene (PS / OPS), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and acrylic (AC). From the viewpoint of strength, heat resistance, and cost, polyethylene terephthalate (PET) film is preferred.

[0066] As shown in Figure 4, the liquid detection sensor 100 includes an electrode substrate 10 and a transmitting unit 70 electrically connected to the electrode substrate 10. The electrode substrate 10 supplies power to the liquid detection sensor 100 for generating an electrical signal. The transmitting unit 70 transmits an electrical signal related to the liquid detection result to the outside. The electrode substrate 10 may also supply power for the transmission of the electrical signal by the transmitting unit 70. The transmitting unit 70 is electrically connected to the electrode substrate 10 at each of the positive electrode 30 and negative electrode 40. In the liquid detection sensor 100 of Figure 4, the electrode substrate 10 is electrically connected to the transmitting unit 70 via a wire section 110. The electrode substrate 10 included in the liquid detection sensor 100 of Figure 4 is the electrode substrate 10 shown in Figures 1 and 2. The liquid detection sensor 100 generates an electrical signal related to the liquid detection result. The liquid detection sensor 100 generates an electrical signal from the current generated by the discharge of the electrode substrate 10. The liquid detection sensor 100 detects the presence or absence of liquid electrically connecting the positive electrode 30 and the negative electrode 40 by generating an electrical signal due to discharge from the electrode substrate 10. The electrode substrate 10 has the positive electrode 30 and the negative electrode 40 electrically separated and arranged on the base material 20. Various adhesives and bonding methods can be used for arrangement. Furthermore, in the electrode substrate 10, when liquid comes into contact with the electrically separated positive electrode 30 and negative electrode 40, discharge immediately begins due to an oxidation-reduction reaction described later.

[0067] As shown in Figure 5, the liquid detection sensor 100 may include a notification unit 80 instead of a transmission unit 70. Figure 5 includes an electrode substrate 10 and a notification unit 80 electrically connected to the electrode substrate 10. The notification unit 80 is electrically connected to the electrode substrate 10 at both the positive electrode 30 and the negative electrode 40. The notification unit 80 notifies the liquid detection result from the liquid detection sensor 100.

[0068] Unlike the examples in Figures 4 and 5, the liquid detection sensor 100 may include either the transmitting unit 70 or the notification unit 80 described above. That is, the liquid detection sensor 100 may include an electrode substrate 10, a transmitting unit 70 electrically connected to the electrode substrate 10, and a notification unit 80 electrically connected to the electrode substrate 10.

[0069] Next, the discharge mechanism of the electrode substrate 10 when the liquid to be detected by the liquid detection sensor 100 penetrates between the positive electrode 30 and the negative electrode 40 of the electrode substrate 10 will be described. Here, for the sake of convenience of explanation, the case where the negative electrode 40 is magnesium (Mg) will be described. The case where the liquid to be detected by the liquid detection sensor 100 is water will be described. When water penetrates between the positive electrode 30 and the negative electrode 40 of the electrode substrate 10, an oxidation reaction shown in the following (1) occurs at the negative electrode 40. In the following (1), the active material of the negative electrode 40 is magnesium. Also, at the positive electrode 30, a reduction reaction shown in the following (2) occurs. In the following (2), the active material of the positive electrode 30 is oxygen. From the above, as the entire electrode substrate 10, the reaction shown in the following (3) occurs, and the electrode substrate 10 discharges. (1) 2Mg → 2Mg

[0071] +4e － (2) O ２ +2H ２ O + 4e － →4OH － (3) 2Mg + O ２ +2H ２ O → 2Mg(OH) ２

[0070] [[ID=​​​​​When the receiving unit 90 receives a detection signal from the transmitting unit 70 of the liquid detection sensor, it detects that a leak or other issue has occurred in the target liquid, notifies people that a water leak or flooding has occurred, and automatically shuts down the device if necessary.

[0073] The electrode substrate of the present invention can be stored by winding it in a spiral or roll shape, and the electrode substrate can be cut to the desired length with a cutting tool such as scissors, a knife, or a cutter. Furthermore, a tape dispenser, such as one used to cut adhesive tape like cellophane tape to the desired length, can be used while the substrate is wound in a roll shape.

[0074] The liquid detection sensor of the present invention is versatile, prevents deterioration of the electrode substrate which serves as the power source even after long-term installation, and the electrode substrate which serves as the power source exhibits excellent power generation performance. Therefore, it can be used in a wide range of liquid detection fields, such as detecting water leaks and roof leaks in buildings, water leaks and oil leaks in various facilities and factories, flooding in roads and underground facilities, detection of dangerous water levels by detecting water levels in rivers and lakes, detection of blood leaks and drug leaks in medical settings, and detection of urination in nursing care settings.

[0075] The present invention can be implemented in various forms with improvements, modifications, or alterations based on the knowledge of those skilled in the art, without departing from its spirit. Furthermore, the invention may be implemented in a form in which any of its defining features is replaced with other technologies, as long as the same function or effect is achieved.

Claims

1. An electrode substrate comprising a substrate having a first surface and a second surface, and a positive electrode and a negative electrode disposed apart from each other on the first surface or the second surface of the substrate, wherein a discharge occurs when a liquid penetrates between the positive electrode and the negative electrode.

2. An electrode substrate according to claim 1, which constitutes the discharge section of a metal-air battery.

3. The electrode substrate according to claim 1, which is flexible.

4. The electrode substrate according to claim 1, wherein the positive electrode comprises a metal layer and a conductive layer, and the metal layer is located between the substrate and the conductive layer.

5. The electrode substrate according to claim 4, wherein the thickness of the conductive layer is greater than or equal to the thickness of the metal layer, and the thickness ratio of the metal layer to the conductive layer is 1:1 to 1:

20.

6. The electrode substrate according to claim 4, wherein the thickness of the conductive layer is smaller than the thickness of the metal layer.

7. The electrode substrate according to claim 4, wherein the thickness of the conductive layer is 80 μm or less.

8. The electrode substrate according to claim 1, wherein the thickness of the positive electrode is 20 μm or more and 200 μm or less.

9. The electrode substrate according to claim 1, wherein the negative electrode contains a metal having a higher ionization tendency than zinc.

10. The electrode substrate according to claim 1, wherein the distance between the positive electrode and the negative electrode is 0.1 mm or more and 100 mm or less.

11. The electrode substrate according to claim 1, wherein each of the positive electrode and the negative electrode extends in the longitudinal direction of the electrode substrate and is separated from each other in the width direction perpendicular to the longitudinal direction.

12. A liquid detection sensor comprising an electrode substrate according to any one of claims 1 to 11, and a transmitting unit electrically connected to the electrode substrate.

13. A liquid detection sensor comprising an electrode substrate according to any one of claims 1 to 11, and a notification unit electrically connected to the electrode substrate.

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