Flexible heater and cold protection tool

Abstract

A flexible heater comprising: a heat generating unit; and a conduction unit that is pressure-bonded to the heat generating unit and is for conducting a current to the heat generating unit, wherein the heat generating unit comprises a first metal porous body, the conduction unit comprises a second metal porous body, the first metal porous body and the second metal porous body each include a skeleton that has a three-dimensional meshlike structure, the volume resistivity ρ1 of the first metal porous body is greater than the volume resistivity ρ2 of the second metal porous body, said volume resistivities are measured at 23°C and according to JIS C 2525:1999, and in a pressure-bonded section of the heat generating unit and the conduction unit, the porosity of the first metal porous body is 90% or less and the porosity of the second metal porous body is 90% or less.

Description

Flexible heaters and cold weather gear 【0001】 This disclosure relates to a flexible heater and a cold-weather device. This application claims priority under Japanese Patent Application No. 2024-215375, filed on 10 December 2024. All contents contained in said Japanese Patent Application are incorporated herein by reference. 【0002】 Conventionally, flexible heaters in which the heating element circuit is covered with a polyimide film are known (Patent Document 1). 【0003】 Japanese Patent Publication No. 2012-134132 【0004】 The flexible heater of this disclosure is a flexible heater comprising a heating element and a conductive element pressed against the heating element and for conducting electric current to the heating element, wherein the heating element is made of a first porous metal, the conductive element is made of a second porous metal, the first porous metal and the second porous metal include a skeleton having a three-dimensional mesh structure, the volume resistivity ρ1 of the first porous metal is greater than the volume resistivity ρ2 of the second porous metal, the volume resistivity is measured at 23°C in accordance with JIS C 2525:1999, and at the pressed portion between the heating element and the conductive element, the porosity of the first porous metal is 90% or less, and the porosity of the second porous metal is 90% or less. 【0005】Figure 1 is a top view of a flexible heater according to one embodiment of the present disclosure. Figure 2 is an example of a cross-sectional view taken along the line X1-X1 in Figure 1. Figure 3 is another example of a cross-sectional view taken along the line X1-X1 in Figure 1. Figure 4 is a top view of another example of a flexible heater according to one embodiment of the present disclosure. Figure 5 is an example of a cross-sectional view taken along the line X2-X2 in Figure 4. Figure 6 is another example of a cross-sectional view taken along the line X2-X2 in Figure 4. Figure 7 is a schematic partial cross-sectional view showing a schematic of a partial cross-section of the skeleton in a porous metal body. Figure 8 is a cross-sectional view taken along the line A-A in Figure 7. Figure 9 is an enlarged schematic diagram focusing on one of the cell portions in a porous metal body having a three-dimensional mesh structure according to Embodiment 1. Figure 10 is a schematic diagram showing one aspect of the shape of a cell portion. Figure 11 is a schematic diagram showing another aspect of the shape of a cell portion. Figure 12 is a schematic diagram showing another aspect of the shape of a cell portion. Figure 13 is a schematic diagram showing an aspect of two joined cell portions. Figure 14 is a schematic diagram showing the configuration of four joined cell sections. Figure 15 is a schematic diagram showing one configuration of a three-dimensional network structure formed by the joining of multiple cell sections. 【0006】 In the flexible heater described in Patent Document 1, a metal terminal plate, to which lead wires are joined by welding, is welded to the connection end of a heating element circuit made of metal foil. At the welded joint, the metal hardens due to the effects of heat, reducing the flexibility of the welded joint. For this reason, there is a need for a flexible heater with excellent flexibility at the joint between the heating element and the conductive element. 【0007】 Therefore, the present disclosure aims to provide a flexible heater with excellent flexibility at the joint between the heating element and the conductive element, and a cold-weather protection device equipped therewith. 【0008】 According to this disclosure, it is possible to provide a flexible heater with excellent flexibility at the joint between the heating element and the conductive element, and a cold-weather protection device equipped therewith. 【0009】First, embodiments of the present disclosure will be listed and described. (1) The flexible heater of the present disclosure is a flexible heater comprising a heating element and a conductive element pressed against the heating element and for conducting electric current to the heating element, wherein the heating element is made of a first porous metal, the conductive element is made of a second porous metal, the first porous metal and the second porous metal include a skeleton having a three-dimensional mesh structure, the volume resistivity ρ1 of the first porous metal is greater than the volume resistivity ρ2 of the second porous metal, the volume resistivity is measured at 23°C in accordance with JIS C 2525:1999, and at the pressed portion between the heating element and the conductive element, the porosity of the first porous metal is 90% or less, and the porosity of the second porous metal is 90% or less. 【0010】 This disclosure makes it possible to provide a flexible heater with excellent flexibility at the joint between the heating element and the conductive element. The reason for this is as follows. 【0011】 In the flexible heater of this disclosure, the heating element and the conductive element are made of a porous metal having a three-dimensional mesh structure. The porous metal has excellent flexibility. Furthermore, the heating element and the conductive element are joined by crimping. Therefore, in the flexible heater of this disclosure, the excellent flexibility of the porous metal is maintained at the joint (corresponding to the crimped part) between the heating element and the conductive element. As a result, the flexible heater as a whole has excellent flexibility and can be molded into a shape according to the application. In this disclosure, the "crimped part between the heating element and the conductive element" of the flexible heater of Embodiment 1 is synonymous with the "joint between the heating element and the conductive element". 【0012】 In the flexible heater described in Patent Document 1, heating during welding causes surface oxidation and heat diffusion in the welded area, reducing the mechanical strength of the metal and decreasing the durability of the flexible heater. Furthermore, the electrical resistance of the welded area tends to be higher than that of the heating element circuit. In this case, the welded area overheats and deteriorates, reducing the durability of the flexible heater. 【0013】In the flexible heater of this disclosure, the heating element and the conductive element are joined by crimping. Therefore, in the flexible heater of this disclosure, a decrease in the mechanical strength of the metal is less likely to occur at the joint (corresponding to the crimped part) between the heating element and the conductive element, improving the durability of the flexible heater. In addition, the electrical resistance of the joint is less likely to be higher than the electrical resistance of the heating element. Thus, deterioration due to heat generation at the joint does not occur, improving the durability of the flexible heater. 【0014】 In the flexible heater of this disclosure, the heating element and the conductive element are made of a porous metal having a three-dimensional mesh structure. The porous metal is lightweight. Therefore, the weight of the flexible heater can be reduced. 【0015】 (2) In (1) above, the ratio ρ1 / ρ2 of the volume resistivity ρ1 of the first metal porous to the volume resistivity ρ2 of the second metal porous may be 2.5 or more. This suppresses heat generation in the conductive part and reduces power consumption when heating the heating part to the desired temperature. 【0016】 (3) In (1) or (2) above, the framework of the first porous metal may contain nickel-chromium as the main component, and the framework of the second porous metal may contain nickel-cobalt, nickel, or copper as the main component. This makes it possible to increase the difference in volume resistivity between the heating element and the conductive element while maintaining the strength of the heating element. 【0017】 For example, if both the framework of the first and second porous metals contain nickel as the main component, the heat-generating portion should have a basis weight of 100 g / m². ２ The first porous metal material is used, and the conductive part has a basis weight of 300 g / m². ２ By using the second metal porous material, it is possible to set ρ1 / ρ2 = 3. In this case, the basis weight of the heat-generating part must be less than that of the conductive part, which reduces the strength of the heat-generating part. As in (3) above, if the volume resistivity of the main component of the framework of the first metal porous material is greater than the volume resistivity of the main component of the framework of the second metal porous material, it is no longer necessary to reduce the basis weight of the first metal porous material less than that of the conductive part, which is advantageous from the viewpoint of the strength of the heat-generating part. 【0018】 (4) In (1) or (2) above, the framework of the first porous metal may contain nickel cobalt as its main component, and the framework of the second porous metal may contain nickel or copper as its main component. This makes it possible to increase the difference in volume resistivity between the heating element and the conductive element while maintaining the strength of the heating element. 【0019】 (5) In (1) or (2) above, the framework of the first porous metal may contain nickel as the main component, and the framework of the second porous metal may contain copper as the main component. This makes it possible to increase the difference in volume resistivity between the heating part and the conductive part while maintaining the strength of the heating part. 【0020】 (6) The cold-weather gear of the present disclosure is a cold-weather gear equipped with any of the flexible heaters described in (1) to (5) above. The flexible heater has excellent flexibility, excellent moldability, and excellent durability, and is lightweight. Therefore, the cold-weather gear equipped with the flexible heater also has excellent flexibility, excellent moldability, and excellent durability, and is lightweight. 【0021】 Specific examples of the flexible heater and cold-weather protection equipment described herein will be explained below with reference to the drawings. In the drawings of this disclosure, the same reference numerals represent the same or equivalent parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been modified as appropriate for clarity and simplification of the drawings and do not necessarily represent actual dimensional relationships. 【0022】 In this specification, the notation "A to B" means A or greater and B or less. If no unit is specified for A, but a unit is specified only for B, then the unit for A and the unit for B are the same. 【0023】 In this specification, when compounds and other elements are represented by chemical formulas, unless otherwise specified, the atomic ratios should include all conventionally known atomic ratios and should not necessarily be limited to those within the stoichiometric range. 【0024】In this disclosure, if one or more numerical values ​​are listed as the lower and upper limits of a numerical range, any combination of any one numerical value listed as the lower limit and any one numerical value listed as the upper limit shall also be disclosed. 【0025】 In this disclosure, “equipment,” “includes,” “possesses,” and variations thereof are open-ended terms. Open-ended terms may or may not include additional elements in addition to the essential elements. The statement “consists of” is a closed term. However, even a configuration expressed in closed terms may include additional elements that are usually incidental or irrelevant to the subject technology. 【0026】 [Embodiment 1: Flexible Heater] <Structure of Flexible Heater> As shown in Figure 1, the flexible heater 4 of one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 1") comprises a heating element 1 and a conductive element 2 for conducting electric current to the heating element 1. In Figure 1, the conductive element 2 consists of one pair of conductive elements 2. By connecting a power supply unit (not shown) to the conductive element 2 and supplying electric current from the power supply unit to the heating element 1 via the conductive element 2, the heating element 1 generates heat. In Figure 1, one pair of conductive elements 2 are crimped onto one heating element 1, but the number of conductive elements 2 is not limited to one pair. The number of conductive elements 2 crimped onto one heating element 1 may be appropriately set based on the size and shape of the heating element 1 so that the heating element 1 can have a uniform temperature distribution when generating heat. The number of conductive elements 2 crimped onto one heating element 1 may be one pair, or it may be two pairs or more and five pairs or less. 【0027】 The flexible heater of Embodiment 1 is particularly suitable as a flexible heater in which the heating element heats up to 30°C or more and up to 300°C or less. 【0028】 <Heating element> In Embodiment 1, the heating element is made of a first porous metal. The heating element may be made of a sheet-like first porous metal. The heating element may be made of a single sheet-like first porous metal. The heating element may be made of a laminate in which two or more sheet-like first porous metals are stacked. 【0029】The shape and size of the heating part are not particularly limited and can be appropriately set according to the application. The shape of the main surface of the heating part may be, for example, polygonal, circular, or other shapes suitable for the application. The size of the main surface of the heating part may be, for example, 100 mm ２ or more and 5 m ２ or less, 1000 mm ２ or more and 3 m ２ or less, or 0.1 m ２ or more and 1 m ２ or less. 【0030】 In the region other than the crimping part, the thickness of the heating part may be 0.05 mm or more and 2.2 mm or less, 0.1 mm or more and 1.5 mm or less, or 0.1 mm or more and 1.2 mm or less. When the thickness of the heating part is 0.05 mm or more, the strength of the heating part is improved, and the heating part can have cushioning properties. When the thickness of the heating part is 2.2 mm or less, the flexibility of the heating part is improved. 【0031】 The thickness of the above-mentioned heating part is measured by a digital thickness gauge. The thickness measurement is performed at three arbitrarily set locations within a region where the distance from the outer edge of the heating part is 2 mm or more. The average of the thicknesses at the three locations is calculated. In the present disclosure, the average of the thicknesses at the three locations corresponds to the thickness of the heating part. The thicknesses of the conductive part, the crimping part, the first metal porous body, and the second metal porous body described below are also measured by the same method. 【0032】 <Conductive part> In Embodiment 1, the conductive part is made of a second metal porous body. The conductive part may be made of a sheet-like second metal porous body. The conductive part may be made of a single sheet-like second metal porous body. The conductive part may be made of a laminate in which two or more sheet-like second metal porous bodies are laminated. 【0033】 The shape and size of the conductive part are not particularly limited and can be appropriately set according to the application. The shape of the main surface of the conductive part may be, for example, polygonal, circular, or other shapes suitable for the application. The size of the main surface of the conductive part may be, for example, 100 mm ２ or more and 5 m ２It may also be 1000 mm or more ２ and 3 m or less ２ It may also be 0.1 m or more ２ and 1 m or less. ２ It may be less. 【0034】 In the region other than the crimping portion, the thickness of the conductive portion may be 0.05 mm or more and 2.2 mm or less, 0.1 mm or more and 1.5 mm or less, or 0.1 mm or more and 1.2 mm or less. When the thickness of the conductive portion is 0.05 mm or more, the strength of the conductive portion is improved, and the conductive portion can have cushioning properties. When the thickness of the conductive portion is 2.2 mm or less, the flexibility of the conductive portion is improved. 【0035】 <Crimping portion> In Embodiment 1, the heat generating portion and the conductive portion are crimped to form a crimping portion. In the crimping portion, the skeleton of the first metal porous body and the skeleton of the second metal porous body are intertwined, and the first metal porous body and the second metal porous body are joined. 【0036】 As shown in FIGS. 1 to 3, the crimping portion 3 may be formed by crimping a part near the outer edge of one main surface of a sheet-like heat generating portion 1 and a part near the outer edge of one main surface of a sheet-like conductive portion 2 facing each other. 【0037】 As shown in FIGS. 4 to 6, the crimping portion 3 may be formed by crimping the vicinity of the outer edge of a sheet-like heat generating portion 1 while the two sheet-like conductive portions 2 are arranged so as to sandwich it. 【0038】 The length of the overlap L1 of the crimping portion may be 2 mm or more. According to this, the adhesive force between the first metal porous body and the second metal porous body in the crimping portion is improved. The length of the overlap L1 of the crimping portion corresponds to the distance between the outer edge of the heat generating portion and the outer edge of the conductive portion along the direction of current flow in the crimping portion. The length of the overlap L1 of the crimping portion may be 2 mm or more and 20 mm or less, 5 mm or more and 15 mm or less, or 8 mm or more and 12 mm or less. 【0039】The thickness of the crimped portion may be 0.05 mm or more and 2.2 mm or less, 0.1 mm or more and 1.5 mm or less, 0.2 mm or more and 1.2 mm or less, or 0.2 mm or more and 0.5 mm or less. A thickness of 0.05 mm or more in the crimped portion improves the strength of the crimped portion and allows the crimped portion to have cushioning properties. A thickness of 2.2 mm or less in the crimped portion improves the adhesive strength between the first porous metal and the second porous metal at the crimped portion. 【0040】 As shown in Figures 3 and 5, in a flexible heater, the thickness of the crimped portion 3, the thickness of the heating portion 1 other than the crimped portion 3, and the thickness of the conductive portion 2 other than the crimped portion 3 may be different. The thickness of the crimped portion 3 may be less than the sum of the thickness of the heating portion 1 other than the crimped portion 3 and the thickness of the conductive portion 2 other than the crimped portion 3. The thickness of the crimped portion 3 may be less than the thickness of the heating portion 1 other than the crimped portion 3 and the thickness of the conductive portion 2 other than the crimped portion 3. 【0041】 As shown in Figures 2 and 6, in a flexible heater, the thickness of the crimped portion 3, the thickness of the heating portion 1 other than the crimped portion 3, and the thickness of the conductive portion 2 other than the crimped portion 3 may be the same. In this case, the heating portion 1 and the conductive portion 2 will be flush with each other in the flexible heater. 【0042】 In a flexible heater, the ratio T1 / T of the thickness T1 of the heating element other than the crimped part to the thickness T of the crimped part may be 1 or more and 4 or 2 or more and 3 or 3. In a flexible heater, the ratio T2 / T of the thickness T2 of the conductive element other than the crimped part to the thickness T of the crimped part may be 1 or more and 4 or 2 or more and 3 or 3. 【0043】 The shape and size of the crimped portion are not particularly limited as long as current can be conducted through the heating portion, and can be set appropriately depending on the application. For example, the ratio L3 / L2 of the length of the crimped portion along the outer edge of the heating portion to the total length L2 of the outer edge of the heating portion may be 0.01 or more and 0.5 or less. 【0044】<Structure of the First and Second Metal Porous Materials> In Embodiment 1, the first and second metal porous materials (hereinafter, the first and second metal porous materials are collectively referred to as "metal porous materials") have a three-dimensional network structure. In this disclosure, a three-dimensional network structure means a structure in which the constituent solid components are spread out in a network shape in three dimensions. Here, the solid components are metals, etc. 【0045】 The frameworks of the first and second porous metals will be explained using Figures 7 and 8. As shown in Figure 7, the framework 12 consists of a skeletal body 11 containing a metal element and a hollow interior 13 surrounded by the skeletal body 11. The framework 12 forms the support and node portions, which will be described later. The first and second porous metals include pore portions 14 defined by the outer edge of the framework 12. 【0046】 As shown in Figure 8, the skeleton 12 has a hollow cylindrical shape with an interior 13 surrounded by the skeleton body 11, and the shape of the cross section perpendicular to the longitudinal direction of the skeleton 12 may be triangular. The cross section of the skeleton 12 may also be a polygon such as a square or hexagon, or it may be circular. 【0047】 Because the framework 12 has a hollow interior 13, the first and second porous metals are very lightweight. 【0048】 Because the framework 12 has a hollow interior 13, the first and second porous metals deform easily when an external force is applied. Therefore, the first and second porous metals can have excellent flexibility and excellent moldability. Furthermore, by applying an external force to the first and second porous metals and crushing the pores 14, it is possible to reduce the porosity of the first and second porous metals. In addition, because the framework 12 has a hollow interior 13, the porous metals are very lightweight. 【0049】In the following, to facilitate understanding of the three-dimensional network structure, the constituent units of the three-dimensional network structure will be described as cell portions 20. Figure 9 is an enlarged schematic diagram of one cell portion 20 constituting the three-dimensional network structure of the first porous metal and the second porous metal in Embodiment 1. As shown in Figure 15, the three-dimensional network structure 30 is formed by joining a plurality of cell portions 20. 【0050】 As shown in Figures 9 and 10, the cell portion 20, which is the constituent unit of the three-dimensional mesh structure, is composed of multiple support portions 7 and node portions 6 that connect the multiple support portions 7. Therefore, the three-dimensional mesh structure can be described as being composed of multiple support portions 7 and node portions 6 that connect the multiple support portions 7. In the following, the support portions 7 and node portions 6 will be described separately, but there is no clear boundary between the two, and the multiple support portions 7 and the multiple node portions 6 together constitute the three-dimensional mesh structure. In the following, the three-dimensional mesh structure composed of the support portions 7 and node portions 6 will also be referred to as the skeleton. In the following, for ease of understanding, the shape of the cell portion 20 in Figure 9 will be considered as a regular dodecahedron as shown in Figure 10 for explanation. 【0051】 Multiple support columns 7 and multiple node columns 6 form a frame section 10, which is a planar polygonal structure. A planar polygon means that it is a polygon when viewed in plan. In Figure 10, the planar polygonal structure is a regular pentagon, but the shape of the planar polygonal structure is not limited to a regular pentagon. The planar polygonal structure may be a triangle, a quadrilateral, a hexagon, or other polygon. The frame section 10 forms a planar polygonal hole with the multiple support columns 7 and the multiple node columns 6. 【0052】Multiple frame sections 10 are combined to form a cell section 20, which is a three-dimensional polyhedral structure. One support section 7 and one node section 6 are shared by the multiple frame sections 10. The shape of the node section 6 may be a sharp-edged shape with vertices, a planar shape with chamfered vertices, or a curved shape with rounded vertices. In Figure 10, the three-dimensional polyhedral structure is a dodecahedron, but it may be other polyhedra such as a cube, icosahedron (see Figure 11), truncated icosahedron (see Figure 12), etc. The cell section 20 forms a three-dimensional space enclosed by a virtual plane A defined by each of the multiple frame sections 10. 【0053】 As shown in Figures 13, 14, and 15, a three-dimensional mesh structure 30 is formed by combining multiple cell portions 20. The frame portion 10 is shared by multiple cell portions 20. The frame portion 10 may be shared by two cell portions 20. The three-dimensional mesh structure 30 can also be described as consisting of multiple frame portions 10. The three-dimensional mesh structure 30 can also be described as consisting of multiple cell portions 20. In Embodiment 1, since the porous metal has a three-dimensional mesh structure 30, it can have interconnected pores. 【0054】 In Embodiment 1, the cell portion 20 may be formed by a plurality of frame portions 10 having different sizes and planar shapes. The three-dimensional mesh structure may be formed by a plurality of cell portions 20 having different sizes and three-dimensional shapes. The three-dimensional mesh structure may include a portion of frame portions 10 that do not have planar polygonal holes, or it may include a portion of cell portions 20 that do not have three-dimensional spaces and are solid inside. 【0055】In Embodiment 1, the first and second porous metals have a three-dimensional mesh structure composed of planar polygonal holes formed by the frame portion and three-dimensional spaces formed by the cell portion. The first and second porous metals in Embodiment 1 can be clearly distinguished from two-dimensional mesh structures such as perforated metal having only planar holes, and meshes formed by two-dimensionally woven metal wires. In Embodiment 1, the porous metals have multiple support portions and multiple node portions integrated to form a three-dimensional mesh structure. Therefore, they can be clearly distinguished from structures such as metal meshes and nonwoven fabrics formed by the entanglement of metal fibers, which are the constituent units. 【0056】 <Volume resistivity ρ1 of the first porous metal and volume resistivity ρ2 of the second porous metal> In Embodiment 1, the volume resistivity ρ1 (Ω・m) of the first porous metal is greater than the volume resistivity ρ2 (Ω・m) of the second porous metal. As a result, the heating element made of the first porous metal generates heat. 【0057】 In this disclosure, the volume resistivity ρ1 of the first porous metal and the volume resistivity ρ2 of the second porous metal are measured at 23°C in accordance with JIS C 2525:1999 "Test Methods for Conductor Resistivity and Volume Resistivity of Metallic Resistive Materials". The measurement method is four-terminal resistance measurement using a resistance meter. The measuring device used is a HIOKI BT3562-01 battery tester. 【0058】 The ratio ρ1 / ρ2, which is the ratio of the volume resistivity ρ1 of the first metal porous material to the volume resistivity ρ2 of the second metal porous material, may be 2.5 or greater, 2.8 to 100, or 3.0 to 90. When ρ1 / ρ2 is 2.5 or greater, heat generation in the conductive part can be suppressed, and power consumption when heating the heating part to the desired temperature can be reduced. When ρ1 / ρ2 is 100 or less, it is possible to prevent the voltage from rising too high. 【0059】 The volume resistivity ρ1 of the first porous metal is 1 × 10⁻⁶ －７ Ω・m or more 1×10 －４ It is also acceptable if it is less than Ω·m, 5 × 10 －７ Ω・m or more 5×10 －５It may be less than or equal to Ω·m, or 1 × 10⁻⁶ －６ Ω・m or more 1×10 －５ It is also acceptable if it is less than Ω·m. 【0060】 The volume resistivity ρ² of the second-order porous metal is 0.4 × 10⁻⁶. －７ Ω・m or more 0.4×10 －４ It is also acceptable if it is less than Ω·m, 2 × 10 －７ Ω・m or more 1×10 －５ It can be less than or equal to Ω·m, or 3 × 10 －７ Ω・m or more 1×10 －６ It is also acceptable if it is less than Ω·m. 【0061】 <<Composition of the frameworks of the first and second metal porous materials>> In Embodiment 1, the composition of the frameworks of the first and second metal porous materials can be appropriately selected such that the volume resistivity ρ1 of the first metal porous material is greater than the volume resistivity ρ2 of the second metal porous material. 【0062】 The framework of the first porous metal mainly contains nickel-chromium, and the framework of the second porous metal may mainly contain nickel-cobalt, nickel, or copper. 【0063】 In this disclosure, "the framework of the first porous metal contains nickel-chromium as its main component" means that the nickel-chromium content of the framework body of the first porous metal is 90% by mass or more. In this disclosure, "the framework of the second porous metal contains nickel-cobalt, nickel, or copper as its main component" means that the nickel-cobalt, nickel, or copper content of the framework body of the second porous metal is 90% by mass or more. 【0064】 The framework of the first metal porous material mainly contains nickel-cobalt, and the framework of the second metal porous material may mainly contain nickel or copper. 【0065】In this disclosure, "the framework of the first porous metal contains nickel-cobalt as its main component" means that the nickel-cobalt content of the framework body of the first porous metal is 90% by mass or more. In this disclosure, "the framework of the second porous metal contains nickel or copper as its main component" means that the nickel or copper content of the framework body of the second porous metal is 90% by mass or more. 【0066】 The framework of the first porous metal may contain nickel as its main component, and the framework of the second porous metal may contain copper as its main component. 【0067】 In this disclosure, "the framework of the first porous metal contains nickel as its main component" means that the nickel content of the framework of the first porous metal is 90% by mass or more. In this disclosure, "the framework of the second porous metal contains copper as its main component" means that the copper content of the framework of the second porous metal is 90% by mass or more. 【0068】 Insofar as it does not impair the effects of this disclosure, the framework of the porous metal may include impurities in addition to the metal described above. Examples of impurities include compounds such as oxides, nitrides, sulfides, chlorides, and carbides, as well as carbon. 【0069】 The composition of the metal porous structure is measured using ICP (Inductively Coupled Plasma). 【0070】 <<Porosity of the First and Second Metal Porous Materials>> In the crimped portion between the heating element and the conductive element of the flexible heater of Embodiment 1, the porosity of the first metal porous material is 90% or less, and the porosity of the second metal porous material is 90% or less. As a result, the framework of the first metal porous material and the framework of the second metal porous material intertwine in the crimped portion, and the first metal porous material and the second metal porous material are joined together. Generally, the porosity of the first metal porous material and the porosity of the second metal porous material before crimping are 91% or more. 【0071】In the crimped portion described above, the porosity of the first porous metal is 90% or less, but may be 85% or less, or 80% or less. The lower limit of the porosity of the first porous metal is not particularly limited, but from the viewpoint of improving the heat dissipation of the crimped portion, it may be 40% or more. 【0072】 In the crimped portion described above, the porosity of the second metal porous material is 90% or less, but may also be 85% or less, or 80% or less. The lower limit of the porosity of the second metal porous material is not particularly limited, but from the viewpoint of improving the heat dissipation of the crimped portion, it may be 40% or more. 【0073】 The porosity of the regions of the first and second porous metals other than the crimped portions may be 40% to 98%, 50% to 95%, or 60% to 90%. If the porosity is 40% or higher, the first and second porous metals become lighter. If the porosity is 98% or lower, the strength of the first and second porous metals is improved. 【0074】 In this disclosure, the porosity of the first porous metal and the porosity of the second porous metal (hereinafter referred to as "porosity of the porous metal") are defined by the following formula: Porosity of the porous metal [%] = (Volume of pores in the porous metal [cm³] ３ ] / Volume of porous metal [cm³ ３ ]) × 100 In the above formula, the volume of the porous metal is the volume of the external shape of the porous metal. 【0075】 The method for measuring the volume of pores in a porous metal and the volume of the porous metal is as follows: Three-dimensional data of the porous metal is acquired by X-ray CT within a region at a distance of 2 mm or more from the outer edge of the porous metal. Based on this three-dimensional data, the volume of pores and the volume of the porous metal are determined. The volume of the entire X-ray CT measurement area corresponds to the volume of the porous metal in the above formula. The size of the X-ray CT measurement area is 2 mm. ３ This concludes the explanation. The size of the measurement area can be set appropriately according to the size of the object being measured. 【0076】The porosity of the metal porous material (hereinafter also referred to as "second porosity") is calculated by substituting the volume of pores and the volume of the metal porous material obtained into the above formula. Three non-overlapping measurement areas are set for a single metal porous material that is the object of measurement. The volume of pores and the volume of the metal porous material are determined in each of the three measurement areas, and the second porosity of the metal porous material is calculated. The average of the second porosity of the metal porous material in the three measurement areas is calculated. In this disclosure, the average of the second porosity of the metal porous material in the three measurement areas corresponds to the porosity of the metal porous material. 【0077】 <Method for Manufacturing a Flexible Heater> The method for manufacturing the flexible heater of Embodiment 1 is described below. A first porous metal is prepared as the material for the heating element. A second porous metal is prepared as the material for the conductive element. The first porous metal and the second porous metal can be commercially available porous metals such as "Cellmet®" manufactured by Sumitomo Electric Industries, Ltd. 【0078】 If porous metals are not available on the market, they may be manufactured by the following method. Prepare a sheet of resin molded material having a three-dimensional network structure. Polyurethane resin, melamine resin, etc., can be used as the resin molded material. Next, perform a conductive treatment step to form a conductive layer on the surface of the resin molded material. Conductive treatment can be performed, for example, by applying a conductive paint containing conductive particles such as carbon or conductive ceramic, forming a layer of conductive metals such as nickel and copper by electroless plating, or forming a layer of conductive metals by vapor deposition or sputtering. Next, use the resin molded material with the conductive layer formed on its surface as a substrate and perform a plating step to electroplat a metal such as nickel that constitutes the framework. Electroplating can be performed by known methods. 【0079】 Finally, by performing a removal process to remove the resin molded body used as the base material through heat treatment or the like, a porous metal body having a three-dimensional network structure can be obtained. 【0080】The first and second porous metals are sheet-shaped. The thickness of the first porous metal may be between 0.8 mm and 2.2 mm. The thickness of the second porous metal may be between 0.8 mm and 2.2 mm. 【0081】 The porosity of the first metal porous material may be between 90% and 98%. The porosity of the second metal porous material may be between 90% and 98%. 【0082】 The first and second porous metals may be cut into shapes suitable for their intended use. 【0083】 A portion of the outer edge of the main surface of the first porous metal and a portion of the outer edge of the main surface of the second porous metal are placed opposite each other and overlapped. At this time, the overlap portion of the first porous metal and the second porous metal is adjusted to be 2 mm or more. The overlap portion is pressed with a roll press to compress the first porous metal and the second porous metal together, thereby obtaining the flexible heater of Embodiment 1. During the pressing process, the compression ratio of the first porous metal and the second porous metal is adjusted to be 50% or more. As a result, the porosity of the first porous metal and the pores of the second porous metal can be set to 90% or less at the compression portion between the heating element and the conductive element. 【0084】 In the above manufacturing method, the first porous metal and the second porous metal are pressed together by press working, thus maintaining the excellent flexibility of the porous metal at the pressed portion (joint). Therefore, the flexible heater as a whole can have excellent flexibility. 【0085】 [Embodiment 2: Cold Weather Gear] One embodiment of the present disclosure (hereinafter also referred to as "Embodiment 2") is a cold weather gear equipped with the flexible heater of Embodiment 1. Examples of cold weather gear include blankets, clothing, steering wheel heaters, and seat heaters. 【0086】 The flexible heater of Embodiment 1 has excellent flexibility at the joint between the heating element and the conductive element, and is lightweight. Therefore, blankets or clothing equipped with this flexible heater have excellent flexibility and moldability, are lightweight, and offer a superior user experience. 【0087】 The flexible heater of Embodiment 1 is applicable to handle heaters of various shapes because it has excellent flexibility at the joint between the heating element and the conductive element. 【0088】 The flexible heater of Embodiment 1 has excellent flexibility at the joint between the heating element and the conductive element. Therefore, a sheet heater equipped with this flexible heater has excellent flexibility and a superior user experience. 【0089】 This embodiment will be described in more detail by reference to examples. However, this embodiment is not limited by these examples. 【0090】 [Fabrication of Flexible Heaters] Flexible heaters were fabricated for each sample using the following procedure. "Cellmet®," manufactured by Sumitomo Electric Industries, Ltd., was prepared as the first and second porous metal bodies. The material and porosity of the frameworks of the first and second porous metal bodies used in each sample are shown in Table 1. In the frameworks of the first and second porous metal bodies used in each sample, the content of the metal or alloy shown in the "Material" column of Table 1 was 95% by mass or more. 【0091】 A first porous metal was cut to prepare one 1 cm x 4 cm rectangular sheet for the heating element. A second porous metal was cut to prepare two 2 cm x 4 cm rectangular sheets for the conductive element. The main surface of the heating element sheet made of the first porous metal was placed opposite the main surfaces of the two conductive element sheets made of the second porous metal, in the positional relationship shown in Figure 1, to obtain a sample. The overlap L1 of the overlapping portion between the first and second porous metal was set to 10 mm. The entire sample was pressed using a roll press to press the first and second porous metal together, thereby obtaining a flexible heater for each sample. The thickness of the pressed portion after pressing in each sample is shown in Table 1. The cross-section of the flexible heater for each sample had the shape shown in Figure 2. 【0092】 【0093】For each sample of flexible heater, the volume resistivity ρ1 of the first metal porous material in the heat-generating portion other than the crimped portion (referred to as "heat-generating portion" in Table 2), and the volume resistivity ρ2 of the second metal porous material in the conductive portion other than the crimped portion (referred to as "conductive portion" in Table 2) were measured using the method described in Embodiment 1. The results are shown in Table 2. 【0094】 In the flexible heaters of each sample, the thickness and porosity of the first and second metal porous materials in the crimped portion were measured using the method described in Embodiment 1. The results are shown in Table 2. The thickness and porosity of the first metal porous material in the heating portion other than the crimped portion, and the thickness and porosity of the second metal porous material in the conductive portion other than the crimped portion, remained at the values ​​shown in Table 1. 【0095】 【0096】 As a comparative example (Sample 1-1), a heater having the same appearance as Sample 1 was prepared by welding together a nichrome metal plate with the same shape as the heating element of Sample 1 and a copper metal plate with the same shape as the conductive element of Sample 1. 【0097】 [Flexibility of the Joint (Crimped Section)] The flexibility of the joint (corresponding to the crimped section in samples 1 to 7) of each sample was confirmed by bending it along a φ50 mm cylinder. If the joint conforms to the cylinder without any gaps, the joint is judged to have excellent flexibility. 【0098】 The joints (compressed areas) of samples 1 to 7 were confirmed to have excellent flexibility. The joint of sample 1-1 lacked sufficient flexibility. 【0099】 [Durability Test] Durability tests were conducted using the flexible heaters of each sample in the following manner. A DC power supply was prepared, and current terminals were connected to the ends of each conductive part. A terminal connected to a voltmeter was connected to the conductive part between the current terminals and the heating part. A thermocouple was set up in contact with the heating part, and current was applied to the heating part until it reached 300°C while monitoring its temperature. 【0100】The resistance value R1 at the point when the heating element reached 300°C and the resistance value R2 100 hours after the heating element reached 300°C were measured in accordance with JIS C 2525:1999. The percentage change in resistance value R2 relative to resistance value R1 was calculated. The results are shown in the "Resistance Change Rate" column of Table 2. If the change rate is 10% or less, the flexible heater is judged to have excellent durability. 【0101】 The flexible heaters of samples 1 to 7 were confirmed to have excellent durability. 【0102】 While embodiments and examples of this disclosure have been described above, it is intended from the outset that the configurations of each of the embodiments and examples described above may be combined or modified in various ways as appropriate. The embodiments and examples disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the embodiments and examples described above, and all modifications within the scope of the claims are intended to be included in the meaning of equivalences. 【0103】 1 Heating section, 2 Conductive section, 3 Crimping section, 4 Flexible heater, 6 Node section, 7 Support section, 10 Frame section, 11 Skeleton body, 12 Skeleton, 13 Interior, 14 Pore section, 20 Cell section, 30 Three-dimensional mesh structure.

Claims

1. A flexible heater comprising a heating element and a conductive element pressed against the heating element and for conducting electric current to the heating element, wherein the heating element is made of a first porous metal, the conductive element is made of a second porous metal, the first porous metal and the second porous metal include a skeleton having a three-dimensional mesh structure, the volume resistivity ρ1 of the first porous metal is greater than the volume resistivity ρ2 of the second porous metal, the volume resistivity is measured at 23°C in accordance with JIS C 2525:1999, and at the pressed portion between the heating element and the conductive element, the porosity of the first porous metal is 90% or less, and the porosity of the second porous metal is 90% or less.

2. The flexible heater according to claim 1, wherein the ratio ρ1 / ρ2 of the volume resistivity ρ1 of the first metal porous to the volume resistivity ρ2 of the second metal porous is 2.5 or more.

3. The flexible heater according to claim 1 or claim 2, wherein the framework of the first porous metal body mainly contains nickel-chromium, and the framework of the second porous metal body mainly contains nickel-cobalt, nickel, or copper.

4. The flexible heater according to claim 1 or claim 2, wherein the framework of the first porous metal body mainly contains nickel cobalt, and the framework of the second porous metal body mainly contains nickel or copper.

5. The flexible heater according to claim 1 or claim 2, wherein the framework of the first porous metal body mainly contains nickel, and the framework of the second porous metal body mainly contains copper.

6. A cold-weather device comprising a flexible heater according to any one of claims 1 to 5.

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