Heater element

Abstract

Provided is a heater element that can suppress short circuits and does not readily allow condensation to stay behind as droplets. A heater element according to the present invention comprises: a honeycomb structure that can generate heat by electrification and has an outer circumferential wall and a partition wall that is provided on the inner circumferential side of the outer circumferential wall, demarcates a plurality of cells that form a channel that extends from a first end surface to a second end surface, and contains a material that has PTC characteristics; a first electrode layer that covers all or a portion of a surface of the partition wall that forms the first end surface; a second electrode layer that covers all or a portion of a surface of the partition wall that forms the second end surface; a first humectant-containing layer that covers a portion of an outer surface of the first electrode layer; and a second humectant-containing layer that covers a portion of an outer surface of the second electrode layer.

Description

[Technical Field]

[0001] This invention relates to a heater element. [Background technology]

[0002] There is a growing demand for improved cabin environments in various vehicles, including automobiles. Specific demands include reducing CO2 in the cabin to suppress driver drowsiness, humidifying the cabin, and removing harmful volatile components such as odor and allergy-inducing substances. While ventilation is an effective measure to meet these demands, it significantly reduces heater energy in winter, leading to decreased energy efficiency. This is particularly problematic for electric vehicles (BEVs), as this energy loss drastically reduces their driving range.

[0003] Therefore, Patent Documents 1 and 2 disclose a vehicle interior air purification system that captures target components such as water vapor and CO2 in the vehicle interior air using a functional material such as an adsorbent, and then reacts or releases the target components by heating and releases them outside the vehicle, thereby regenerating the functional material. Such a vehicle interior purification system requires that there be as much contact between the air and the functional material as possible to ensure the capture performance of the target components, and that the functional material can be heated to a predetermined temperature to promote the regeneration of the functional material. Regeneration is carried out, for example, by removing substances adsorbed on the functional material by an oxidation reaction, or by desorbing and discharging substances adsorbed on the functional material, but in any case, it is necessary to heat the functional material to an appropriate temperature depending on the adsorbed substance.

[0004] As a heating means, a vapor compression heat pump is excellent from the viewpoint of thermal efficiency. However, the vapor compression heat pump has problems such as difficulty in operating when the outside air is extremely low temperature, and difficulty in rapidly warming the vehicle cabin at the time of vehicle startup. Therefore, while using a vapor compression heat pump as the main heating device, it is considered practical to additionally utilize a heater element that uses Joule heat when rapid heating at the time of vehicle startup is required or when the outside air temperature is very low.

[0005] However, a heater element that uses Joule heat has a problem that it is likely to be enlarged and compresses the space inside the vehicle. For this reason, it is desirable to provide a more compact heater element. In this regard, a heater element provided with a honeycomb structure portion having PTC characteristics is known to be advantageous because it can increase the heat transfer area per unit volume and can prevent excessive heat generation (Patent Document 3).

[0006] On the other hand, it has also been pointed out that there is a risk that the electric circuit of a heater element provided with a honeycomb structure portion may be short-circuited by condensed water. In response to such a problem, Patent Document 4 proposes covering at least a part of the honeycomb structure portion with a dense insulating film. Specifically, it is a heater element for vehicle cabin heating that includes a columnar honeycomb structure portion having an outer peripheral wall and partition walls that are disposed on the inner peripheral side of the outer peripheral wall and partition a plurality of cells that form a flow path from a first end face to a second end face, wherein the outer peripheral wall and the partition walls are made of a material having PTC characteristics, and further includes a dense insulating film that covers at least a part of the columnar honeycomb structure portion.

[0007] Patent Document 4 also describes that a conductive member connectable to an external power source is disposed on at least a part of the electrode layer, the conductive member and the electrode layer are electrically connected, and at least a part of the electrode layer and the conductive member are covered with the insulating film. Patent Document 4 also describes resins (such as polyimide resin, polyamide resin, polyamideimide resin, fluororesin, phenolic resin, silicone resin, epoxy resin, furan resin, polyvinylidene fluoride, polyphenylene sulfide, polyetherimide, polysulfone, polyamideimide, etc.), glass, and ceramics as insulating materials. As ceramics, alumina, mullite, and spinel are described. Patent Document 4 also describes that at least a part of the electrode layer and the conductive member are covered with an insulating film.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] Patent Document 4 describes preventing short circuits by covering at least a portion of the honeycomb structure with a dense insulating film, but it does not discuss the necessity of moisture absorption. If condensed condensation remains in the honeycomb structure in the form of water droplets, the flow path within the cell narrows, increasing the airflow resistance of the gas flowing through the honeycomb structure. The condensation may also scatter to other locations inside or outside the heater, potentially causing problems such as electrical short circuits at the scattering location, or the water droplets reaching the passenger compartment and splashing on occupants. Therefore, it is desirable to not only prevent short circuits in the honeycomb heater itself, but also to promptly address the issue of condensation adhering to the honeycomb structure so as not to cause problems in downstream components or in the passenger compartment environment.

[0010] This invention was created in view of the above circumstances, and in one embodiment, aims to provide a heater element that can suppress short circuits and in which condensation water is less likely to remain in the form of water droplets. [Means for solving the problem]

[0011] The inventors of the present invention diligently studied to solve the above problems and found that it is advantageous to cover the outer surface of the electrode layer covering the end face of the honeycomb structure with a moisture-absorbing material-containing layer. The present invention, completed based on this finding, is illustrated as follows.

[0012] [1] A honeycomb structure comprising an outer periphery wall and a partition wall disposed on the inner periphery side of the outer periphery wall, which divides and forms a plurality of cells that form a flow channel extending from a first end face to a second end face, and which contains a material having PTC properties, and which is capable of generating heat by electricity; A first electrode layer covering part or all of the surface of the partition wall forming the first end face; A second electrode layer covering part or all of the surface of the partition wall forming the second end face; A first moisture-absorbing material-containing layer that covers a portion of the outer surface of the first electrode layer; and A second moisture-absorbing material-containing layer that covers a portion of the outer surface of the second electrode layer; A heater element equipped with the following features. [2] The heater element according to [1], wherein the average thickness of at least one of the first moisture-absorbing material-containing layer and the second moisture-absorbing material-containing layer is 10 μm or more and 500 μm or less. [3] A heater element as described in [1] or [2], wherein the maximum water absorption capacity (g) of the heater element per unit volume (1 liter) of the honeycomb structure is 20 to 400 g / liter. [4] A heater element according to any one of the following [1] to [3], wherein the first moisture-absorbing layer and the second moisture-absorbing layer are insulating. [5] A heater element according to any one of the following [1] to [4], wherein the first moisture-absorbing layer and the second moisture-absorbing layer contain an inorganic binder. [6] A heater element according to any one of [1] to [5], wherein the first moisture-absorbing material-containing layer and the second moisture-absorbing material-containing layer contain, in addition to the moisture-absorbing material, a functional material having the function of adsorbing carbon dioxide and / or organic gas components. [7] If the first region is defined as the portion of the cell extending 0.5 cm from the outer surface to the second end face of the first moisture-absorbing material-containing layer, then the maximum water absorption per unit volume (1 liter) of the first region is 90 to 200 g / liter. If the second region is defined as the portion of the cell extending 0.5 cm from the outer surface of the second moisture-absorbing material-containing layer toward the first end face in the direction of cell extension, then the maximum water absorption per unit volume (1 liter) of the second region is 90 to 200 g / liter. A heater element as described in any one of items [1] to [6]. [8] The heater element according to any one of [1] to [7], wherein the average thickness of the first electrode layer and the second electrode layer is 5 μm or more and 100 μm or less. [9] The first moisture-absorbing material-containing layer covers 80% or more of the area of ​​the outer surface of the first electrode layer where the first terminal is not connected. The second moisture-absorbing layer covers 80% or more of the area of ​​the outer surface of the second electrode layer where the second terminal is not connected. A heater element as described in any one of items [1] to [8].

[10] A first terminal connected to the portion of the outer surface of the first electrode layer that is not covered by the first moisture-absorbing material-containing layer; A second terminal connected to the portion of the outer surface of the second electrode layer that is not covered by the second moisture-absorbing material-containing layer; A third moisture-absorbing material-containing layer covering a portion of the outer surface of the first terminal; and A fourth moisture-absorbing material-containing layer covering a portion of the outer surface of the second terminal; A heater element as described in any one of [1] to [9], comprising:

[11] The heater element according to

[10] , wherein the third moisture-absorbing layer and the fourth moisture-absorbing layer are insulating.

[12] The heater element according to

[10] or

[11] , wherein the third moisture-absorbing layer and the fourth moisture-absorbing layer contain an inorganic binder.

[13] A heater element according to any one of the claims

[10] to

[12] , wherein the third moisture-absorbing layer and the fourth moisture-absorbing layer contain, in addition to the moisture-absorbing material, a functional material having the function of adsorbing carbon dioxide and / or organic gas components.

[14] A heater element according to any one of the items [1] to

[13] , wherein the first electrode layer and the second electrode layer contain one or more selected from pure aluminum, aluminum alloy, and stainless steel.

[15] The heater element according to

[14] , wherein the first electrode layer and the second electrode layer have a single layer of pure aluminum, a two-layer structure of an Al-Ni alloy layer and a pure silver layer, or a two-layer structure of an Al-Ni alloy layer and a pure aluminum layer.

[16] The first terminal and the second terminal contain one or more selected from pure aluminum, aluminum alloy, and stainless steel. The first terminal is connected to the portion of the outer surface of the first electrode layer that is not covered by the first moisture-absorbing material-containing layer by welding, brazing, or mechanical contact. The second terminal is connected by welding, brazing, or mechanical contact to the portion of the outer surface of the second electrode layer that is not covered by the second moisture-absorbing material-containing layer. A heater element as described in any one of items

[10] to

[15] .

[17] A heater element according to any one of [1] to

[16] , comprising a fifth moisture-absorbing material-containing layer that covers part or all of the surface of the partition wall forming the flow path inside the cell. [Effects of the Invention]

[0013] According to one embodiment of the present invention, it is possible to provide a heater element that can suppress short circuits and prevents condensation from remaining in the form of water droplets. Furthermore, by providing a functional material-containing layer on the surface of the partition wall that forms the flow path inside the cell of the heater element, which has the function of adsorbing components to be removed from the air, such as water vapor, carbon dioxide, and odor components, it is also possible to contribute to improving the vehicle interior environment. This heater element is useful not only for improving the environment in vehicle interiors but also in any indoor space. [Brief explanation of the drawing]

[0014] [Figure 1A] This is a schematic diagram of a heater element according to one embodiment of the present invention, as viewed from the first end face side. [Figure 1B] Figure 1A is a schematic cross-sectional view along line XX. [Figure 1C] This is a schematic diagram of a heater element according to another embodiment of the present invention, as viewed from the first end face side. [Figure 1D] Figure 1C is a schematic cross-sectional view along line XX. [Figure 2A] This is a schematic diagram showing an example of a heater element assembly, which includes a frame that clamps the heater element from the first and second end faces, as viewed from the first end face side. [Figure 2B]Figure 2A is a schematic cross-sectional view along line XX. [Figure 3A] This is a schematic diagram of another example of a heater element assembly, which includes a frame that clamps the heater element from the first and second end faces, as viewed from the first end face side. [Figure 3B] Figure 3A is a schematic cross-sectional view along line XX. [Figure 4A] This is a schematic diagram showing an example of a heater element assembly, which includes a frame that holds the heater element from the outer surface side of the outer wall, as viewed from the first end face side. [Figure 4B] Figure 4A is a schematic cross-sectional view along line XX. [Figure 4C] This diagram schematically shows how a pair of split members approach the heater element from a direction perpendicular to the direction in which the flow path in the honeycomb structure extends, with the heater element in between. [Figure 5A] This is a schematic diagram of another example of a heater element assembly, which includes a frame that holds the heater element from the outer surface side of the outer wall, as viewed from the first end face side. [Figure 5B] Figure 5A is a schematic cross-sectional view along line XX. [Figure 5C] This is a schematic diagram of yet another example of a heater element assembly, which includes a frame that holds the heater element from the outer surface side of the outer wall, as viewed from the first end face side. [Figure 6] This is a schematic diagram showing an example configuration of an air conditioning system according to one embodiment of the present invention. [Modes for carrying out the invention]

[0015] The embodiments of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to the following embodiments, and it should be understood that modifications, improvements, etc., to the following embodiments, made as appropriate based on the ordinary knowledge of those skilled in the art, without departing from the spirit of the invention, also fall within the scope of the present invention.

[0016] (1. Heater element) The heater element according to an embodiment of the present invention can be suitably used to improve the indoor environment in various vehicles such as automobiles. Vehicles are not particularly limited, but include automobiles and trains. Automobiles are not particularly limited, but include gasoline vehicles, diesel vehicles, gas-fueled vehicles using CNG (compressed natural gas) or LNG (liquefied natural gas), fuel cell vehicles, electric vehicles, and plug-in hybrid vehicles. The heater element according to an embodiment of the present invention is particularly suitable for use in vehicles without internal combustion engines, such as electric vehicles and trains.

[0017] Furthermore, the heater element according to the embodiment of the present invention can be used not only in vehicles but also in buildings such as houses, offices, factories, shops, and warehouses, as well as in vehicles such as ships and airplanes, to improve the interior space of these structures.

[0018] The heater element according to the embodiment of the present invention can be used for heating purposes, and can also be equipped with a function to remove target components from the air, thereby contributing to the improvement of the indoor environment. For example, this function can be added by providing a functional material-containing layer on the surface of the partition wall that forms the flow path inside the cell of the heater element, which has the function of adsorbing target components from the air, such as water vapor, carbon dioxide, and odor components. A moisture-absorbing material-containing layer, which is a type of functional material-containing layer, may also be provided on the surface of the partition wall that forms the flow path inside the cell of the heater element.

[0019] Figure 1A shows a schematic diagram of a heater element 100 according to one embodiment of the present invention, viewed from the first end face side. Figure 1B shows a schematic cross-sectional view of Figure 1A along line XX. Figure 1C shows a schematic diagram of a heater element 100 according to another embodiment of the present invention, viewed from the first end face side. Figure 1D shows a schematic cross-sectional view of Figure 1C along line XX.

[0020] The heater element 100 includes a honeycomb structure having an outer peripheral wall 103 and partition walls 106 disposed on the inner peripheral side of the outer peripheral wall 103, which divide and form a plurality of cells 104 that form a flow path extending from a first end face 101a to a second end face 101b. The heater element 100 includes a first electrode layer 102a that covers part or all of the surface of the partition wall 106 that forms the first end face 101a, and a second electrode layer 102b that covers part or all of the surface of the partition wall 106 that forms the second end face 101b. The heater element 100 includes a first moisture-absorbing material-containing layer 107a that covers a portion of the outer surface of the first electrode layer 102a (indirectly covering the first end face 101a), and a second moisture-absorbing material-containing layer 107b that covers a portion of the outer surface of the second electrode layer 102b (indirectly covering the second end face 101b). The heater element 100 includes a first terminal 109a connected to the portion of the outer surface of the first electrode layer 102a that is not covered by the first moisture-absorbing material-containing layer 107a, and a second terminal 109b connected to the portion of the outer surface of the second electrode layer 102b that is not covered by the second moisture-absorbing material-containing layer 107b. The heater element 100 includes a third moisture-absorbing material-containing layer 111a that covers a portion of the outer surface of the first terminal 109a, and a fourth moisture-absorbing material-containing layer 111b that covers a portion of the outer surface of the second terminal 109b. The heater element 100 includes a fifth moisture-absorbing material-containing layer 113 that covers part or all of the surface of the partition wall 106 that forms a flow path inside the cell 104. The configuration of the heater element 100 will be described in detail below.

[0021] (1-1. Honeycomb structure) The shape of the honeycomb structure is not particularly limited. For example, the outer shape of the cross section perpendicular to the direction in which the flow path of the honeycomb structure extends (the direction in which the cell 104 extends) can be a polygon (quadrilateral (rectangle, square), pentagon, hexagon, heptagon, octagon, etc.), a round shape (circular, elliptical, oval, egg-shaped, oblong, rounded quadrilateral (a quadrilateral composed of curves, where each side and each corner is composed of curves, and the radius of curvature of each side is greater than the radius of curvature of each corner), etc.). Furthermore, if the outer shape of the cross section is a polygon, the corners may be chamfered. To prevent damage to the honeycomb structure and to facilitate wrapping cushioning material around the outer surface, it is particularly preferable that the corners be chamfered with a radius of R, and it is more preferable that there are no corners with a radius of curvature of 5 mm or less, even more preferable that the radius of curvature of the corners be 10 mm or more, and even more preferable that it be 20 mm or more. The upper limit of the radius of curvature of the corners is not limited, but can be 40 mm or less, and is typically 30 mm or less. The end faces (first end face 101a and second end face 101b) have the same shape as the cross-section. In the heater element 100 shown in Figures 1A and 1B, the outer shape of the cross-section of the honeycomb structure is circular, and the overall outer shape of the honeycomb structure is cylindrical. In the heater element 100 shown in Figures 1C and 1D, the outer shape of the cross-section of the honeycomb structure is a rectangle with R-chamfered edges, and the overall outer shape of the honeycomb structure is a rectangular prism with R-chamfered edges.

[0022] The opening shape of cell 104 is not particularly limited, but in a cross section perpendicular to the direction in which the flow path of the honeycomb structure extends, it can be a polygon (quadrilateral (rectangle, square), pentagon, hexagon, heptagon, octagon, etc.), a round shape (circular, elliptical, oval, egg-shaped, oblong, etc.), etc. These shapes may be single or a combination of two or more. Among these shapes, quadrilateral or hexagonal is preferred. By providing cell 104 with such a shape, the pressure loss when air flows can be reduced. If the opening shape of cell 104 is polygonal, the corners may be rounded. Note that the heater element 100 shown in the figure has a square opening shape for cell 104.

[0023] The honeycomb structure may be a honeycomb joint having multiple honeycomb segments and a joining layer that joins the outer surfaces of the multiple honeycomb segments. By using a honeycomb joint, it is possible to increase the total cross-sectional area of ​​the cells 104, which are important for ensuring airflow, while suppressing the occurrence of cracks. The joining layer can be formed using a joining material. The joining material is not particularly limited, but a paste made by adding a solvent such as water to a ceramic material can be used. The joining material may contain a material having PTC properties, or it may contain the same material as the outer wall 103 and the partition wall 106. In addition to its role in joining the honeycomb segments, the joining material can also be used as an outer coating material after the honeycomb segments have been joined.

[0024] From the viewpoints of ensuring the strength of the honeycomb structure, reducing pressure loss when air passes through the cells 104, ensuring the amount of functional material such as a moisture absorber that can be carried, ensuring the contact area with the air flowing inside the cells 104, and electrical resistance between end faces, it is desirable to suitably combine the thickness of the partition wall 106, the cell density, and the cell pitch (or cell opening ratio). In this specification, the thickness of the partition wall 106 refers to the length of the line segment that crosses the partition wall 106 when the centroids of adjacent cells 104 are connected by a line segment in a cross section perpendicular to the direction in which the flow path extends. The thickness of the partition wall 106 refers to the average value of the thicknesses of all partition walls 106. In this specification, cell density is a value obtained by dividing the number of cells by the area of ​​one end face of the honeycomb structure (the total area of ​​the partition wall 106 and cells 104, excluding the outer peripheral wall 103). In this specification, cell pitch refers to a value obtained by the following calculation. First, the area per cell is calculated by dividing the area of ​​one end face of the honeycomb structure (the total area of ​​the partition wall 106 and cells 104, excluding the outer perimeter wall 103) by the number of cells. Next, the square root of the area per cell is calculated and this is defined as the cell pitch. In this specification, the opening ratio of cell 104 is the value obtained by dividing the total area of ​​cells 104 partitioned by partition walls 106 in a cross section perpendicular to the direction in which the flow channels of the honeycomb structure extend by the area of ​​one end face (the total area of ​​partition walls 106 and cells 104 excluding the outer peripheral wall 103). Note that layers provided on partition walls 106, such as electrode layers, moisture-absorbing material-containing layers, and functional material-containing layers, are not considered when calculating the opening ratio of cell 104.

[0025] In an embodiment advantageous in terms of supporting a sufficient amount of functional material, the partition wall thickness is 0.180 mm or less, and the cell density is 100 cells / cm³. 2 The following conditions apply, and the cell pitch is 1.0 mm or more. In a preferred embodiment, the partition wall thickness is 0.130 mm or less, and the cell density is 70 cells / cm³. 2 The following conditions apply, and the cell pitch is 1.2 mm or more. In a more preferred embodiment, the partition wall thickness is 0.100 mm or less, and the cell density is 65 cells / cm³. 2 The following conditions apply, and the cell pitch is 1.3 mm or more.

[0026] In each of the above embodiments, from the viewpoint of ensuring the strength of the honeycomb structure and keeping electrical resistance low, the lower limit of the thickness of the partition wall is preferably 0.010 mm or more, more preferably 0.020 mm or more, and even more preferably 0.030 mm or more. In each of the above embodiments, from the viewpoint of ensuring the strength of the honeycomb structure, keeping electrical resistance low, and increasing the surface area to promote reaction, adsorption, and detachment by the functional material, the lower limit of the cell density is 30 cells / cm². 2 Preferably, it is 35 cells / cm 2 It is more preferable that the rate is 40 cells / cm² or higher. 2 It is even more preferable that the above conditions are met. In each of the above embodiments, from the viewpoints of ensuring the strength of the honeycomb structure portion, keeping the electrical resistance low, and increasing the surface area to promote the reaction, adsorption, and desorption by the functional material, the upper limit of the cell pitch is preferably 2.0 mm or less, more preferably 1.8 mm or less, and even more preferably 1.6 mm or less.

[0027] In an advantageous embodiment from the viewpoint of achieving both reduction of pressure loss and maintenance of strength, the thickness of the partition wall is 0.08 mm or more and 0.36 mm or less, the cell density is 2.54 cells / cm 2 or more and 140 cells / cm 2 or less, and the aperture ratio of the cells is 0.70 or more. In a preferred embodiment, the thickness of the partition wall is 0.09 mm or more and 0.35 mm or less, the cell density is 15 cells / cm 2 or more and 100 cells / cm 2 or less, and the aperture ratio of the cells is 0.75 or more. In a more preferred embodiment, the thickness of the partition wall is 0.10 mm or more and 0.30 mm or less, the cell density is 20 cells / cm 2 or more and 90 cells / cm 2 or less, and the aperture ratio of the cells is 0.77 or more.

[0028] In each of the above embodiments, from the viewpoint of ensuring the strength of the honeycomb structure portion, the upper limit of the aperture ratio of the cells is preferably 0.94 or less, more preferably 0.92 or less, and even more preferably 0.90 or less.

[0029] The thickness of the outer peripheral wall 103 is not particularly limited, but it is preferably determined based on the following viewpoints. First, from the viewpoint of reinforcing the honeycomb structure portion, the thickness of the outer peripheral wall 103 is preferably 0.05 mm or more, more preferably 0.06 mm or more, and even more preferably 0.08 mm or more. On the other hand, from the viewpoints of increasing the electrical resistance to suppress the initial current and reducing the pressure loss when air flows, the thickness of the outer peripheral wall 103 is preferably 1.0 mm or less, more preferably 0.5 mm or less, even more preferably 0.4 mm or less, and even more preferably 0.3 mm or less. In this specification, the thickness of the outer peripheral wall 103 refers to the length in the direction normal to the outer peripheral surface, from the boundary between the outer peripheral wall 103 and the outermost cell 104 or partition wall 106 to the outer peripheral surface of the honeycomb structure, in a cross section perpendicular to the direction in which the flow path extends.

[0030] The length of the flow path in the honeycomb structure and the cross-sectional area perpendicular to the flow path can be adjusted to the required size of the heater element and are not particularly limited. For example, when used in a compact heater element while ensuring a predetermined function, the honeycomb structure may have a length of 2 to 50 mm, typically 5 to 50 mm, in the direction of flow path extension, and a cross-sectional area perpendicular to the direction of flow path extension of 30 to 400 cm². 2 Typically 50-150cm 2 It can be done this way.

[0031] The partition walls 106 that make up the honeycomb structure are made of a material that can generate heat when an electric current is passed through it, and specifically, they are made of a material having PTC (Positive Temperature Coefficient) properties. If necessary, the outer peripheral walls 103 may also be made of a material having PTC properties similar to the partition walls 106.

[0032] When a functional material-containing layer, such as a moisture-absorbing material-containing layer, is provided on the partition wall 106, the functional material-containing layer can be heated by heat transfer from the heat-generating partition wall 106 (and, if necessary, the outer peripheral wall 103). Furthermore, materials with PTC properties have the characteristic that when the temperature rises and exceeds the Curie point, the resistance value increases rapidly, making it difficult for electricity to flow. Therefore, when the heater element 100 becomes hot, the current flowing through the partition wall 106 (and, if necessary, the outer peripheral wall 103) is limited, thereby suppressing excessive heat generation from the heater element 100. Consequently, it is also possible to suppress thermal degradation of the functional material-containing layer caused by excessive heat generation.

[0033] From the viewpoint of obtaining appropriate heat generation, the lower limit of the volume resistivity of a PTC-type material at 25°C is preferably 0.5 Ω·cm or more, more preferably 1 Ω·cm or more, even more preferably 5 Ω·cm or more, and even more preferably 10 Ω·cm or more. From the viewpoint of generating heat with a low drive voltage, the upper limit of the volume resistivity of a PTC-type material at 25°C is preferably 30 Ω·cm or less, more preferably 20 Ω·cm or less, more preferably 18 Ω·cm or less, and even more preferably 16 Ω·cm or less. Therefore, the range of the volume resistivity of a PTC-type material at 25°C can be, for example, 10 Ω·cm or more and 30 Ω·cm or less. In this specification, the volume resistivity of a PTC-type material at 25°C is measured in accordance with JIS K6271:2008.

[0034] From the viewpoint of being electrically conductive and having PTC characteristics, the outer wall 103 and partition wall 106 are preferably made of a material mainly composed of barium titanate (BaTiO3), and more preferably ceramics made of a material mainly composed of barium titanate (BaTiO3)-based crystalline particles in which a portion of Ba is replaced with a rare earth element. In this specification, "main component" means a component whose proportion to the total component exceeds 50% by mass. The content of BaTiO3-based crystalline particles can be determined by fluorescent X-ray analysis. Other crystalline particles can also be measured in the same manner.

[0035] The compositional formula for BaTiO3-based crystal grains in which some of the Ba is replaced by rare earth elements is (Ba 1-x A x It can be represented as TiO3. In the empirical formula, A represents one or more rare earth elements, and 0.0001 ≤ x ≤ 0.010. A is not particularly limited as long as it is a rare earth element, but is preferably one or more selected from the group consisting of La, Ce, Pr, Nd, Eu, Gd, Dy, Ho, Er, Y, and Yb, and is more preferably La. x is preferably 0.001 or more, more preferably 0.0015 or more, from the viewpoint of suppressing excessively high electrical resistance at room temperature. On the other hand, x is preferably 0.009 or less, from the viewpoint of suppressing excessively high electrical resistance at room temperature due to insufficient sintering.

[0036] The content of BaTiO3-based crystalline particles in ceramics, in which a portion of Ba is substituted with rare earth elements, is not particularly limited as long as it constitutes the main component, but is preferably 90% by mass or more, more preferably 92% by mass or more, and even more preferably 94% by mass or more. The upper limit of the content of BaTiO3-based crystalline particles is not particularly limited, but is generally 99% by mass or less, preferably 98% by mass or less.

[0037] From the viewpoint of reducing environmental impact, it is desirable that the materials used for the outer perimeter wall 103 and the partition wall 106 are substantially lead-free (Pb). Specifically, the Pb content of the outer perimeter wall 103 and the partition wall 106 is preferably 0.01% by mass or less, more preferably 0.001% by mass or less, and even more preferably 0% by mass. The low Pb content allows, for example, heated air to be safely directed at living organisms such as humans by contacting the heat-generating partition wall 106. In addition, the Pb content of the outer perimeter wall 103 and the partition wall 106, when converted to PbO, is preferably less than 0.03% by mass, more preferably less than 0.01% by mass, and even more preferably 0% by mass. The lead content can be determined by ICP-MS (inductively coupled plasma mass spectrometry).

[0038] The lower limit of the Curie point of the materials constituting the outer perimeter wall 103 and the partition wall 106 is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 125°C or higher, from the viewpoint of efficiently heating the air. The upper limit of the Curie point is preferably 250°C or lower, more preferably 225°C or lower, even more preferably 200°C or lower, even more preferably 150°C or lower, and even more preferably 130°C or lower, from the viewpoint of safety as a component placed indoors, especially in or near the vehicle compartment. Therefore, the range of the Curie point of the materials constituting the outer perimeter wall 103 and the partition wall 106 can be, for example, 100°C or higher and 130°C or lower.

[0039] The Curie points of the materials constituting the outer perimeter wall 103 and the partition wall 106 can be adjusted by the type and amount of sifter added. For example, the Curie point of barium titanate (BaTiO3) is approximately 120°C, but by substituting some of the Ba and Ti with one or more of Sr, Sn, and Zr, the Curie point can be shifted to a lower temperature.

[0040] In this specification, the Curie point is measured by the following method: The sample is mounted in a sample holder for measurement and placed in a measuring chamber (e.g., MINI-SUBZERO MC-810P, manufactured by ESPEC Corporation). The change in the electrical resistance of the sample with respect to temperature changes as the temperature is raised from 10°C is measured using a DC resistance meter (e.g., Multimeter 3478A, manufactured by YOKOGAWA HEWLETT PACKARD, LTD). The Curie point is defined as the temperature at which the resistance value becomes twice the resistance value at room temperature (20°C) as shown in the electrical resistance-temperature plot obtained from the measurement.

[0041] (1-2. Electrode layer) The first electrode layer 102a is provided on the first end face 101a, and the second electrode layer 102b is provided on the second end face 101b. By applying a voltage between the first electrode layer 102a and the second electrode layer 102b, it is possible to generate heat in the honeycomb structure by Joule heating.

[0042] Specifically, the first electrode layer 102a covers part or all of the surface of the partition wall 106 that forms the first end face 101a. The second electrode layer 102b covers part or all of the surface of the partition wall 106 that forms the second end face 101b. In order to facilitate the spread of current across the entire first end face 101a, the first electrode layer 102a preferably covers 80% or more of the area of ​​the portion of the first end face 101a excluding the opening of the cell 104 (partition wall portion and outer peripheral wall portion), more preferably covers 90% or more, and even more preferably covers 99% or more. Similarly, in order to facilitate the spread of current across the entire second end face 101b, the second electrode layer 102b preferably covers 80% or more of the area of ​​the portion of the second end face 101b excluding the opening of the cell 104 (partition wall portion and outer peripheral wall portion), more preferably covers 90% or more, and even more preferably covers 99% or more.

[0043] The first electrode layer 102a and the second electrode layer 102b are not particularly limited, but for example, a metal or alloy containing at least one selected from Cu, Ag, Al, Ni, and Si can be used. In a preferred embodiment, the first electrode layer 102a and the second electrode layer 102b contain one or more selected from pure aluminum, aluminum alloy, and stainless steel. Alternatively, an ohmic electrode capable of ohmic contact with the outer peripheral wall 103 and / or partition wall 106 having PTC characteristics can be used. For example, an ohmic electrode can be used that contains at least one selected from Al, Au, Ag, and In as a base metal and at least one selected from Ni, Si, Zn, Ge, Sn, Se, and Te for n-type semiconductors as a dopant. Furthermore, the first electrode layer 102a and the second electrode layer 102b may be a single-layer structure or a stacked structure of two or more layers. When the first electrode layer 102a and the second electrode layer 102b have a laminated structure of two or more layers, the materials of each layer may be the same or different. In a preferred embodiment, the first electrode layer 102a and the second electrode layer 102b have a single layer of pure aluminum, a two-layer structure of an Al-Ni alloy layer and a pure silver layer, or a two-layer structure of an Al-Ni alloy layer and a pure aluminum layer.

[0044] The thicknesses of the first electrode layer 102a and the second electrode layer 102b are not particularly limited and can be appropriately set depending on the method of forming the first electrode layer 102a and the second electrode layer 102b. Examples of methods for forming the first electrode layer 102a and the second electrode layer 102b include metal deposition methods such as sputtering, vapor deposition, electrolytic deposition, and chemical deposition. Electrode layers can also be formed by applying electrode paste and then baking it, or by thermal spraying. Furthermore, electrode layers may be formed by joining metal plates or alloy plates, such as perforated metal, that have through holes in locations corresponding to the openings of the cell.

[0045] The average thickness of the first electrode layer 102a and the second electrode layer 102b is not limited, but can be, for example, 5 μm or more and 100 μm or less. The advantage of avoiding abnormal heat generation in the electrode layers is obtained by setting the lower limit of the average thickness of the first electrode layer 102a and the second electrode layer 102b to 5 μm or more, preferably 10 μm or more, and more preferably 20 μm or more. The upper limit of the average thickness of the first electrode layer 102a and the second electrode layer 102b is 100 μm or less, preferably 80 μm or less, and more preferably 60 μm or less. μ By keeping the thickness below m, the rigidity of the electrode layer can be suppressed, which has the advantage of making it less likely to peel off from the end face of the honeycomb structure.

[0046] The average thickness of the first electrode layer 102a is measured by the following procedure. First, a cross-sectional image of the first electrode layer at approximately 50x magnification is obtained using a scanning electron microscope or the like. The cross-section is parallel to the direction in which the flow channels of the honeycomb structure extend. In the cross-sectional image, as illustrated in the partially enlarged view in Figure 1B, the first electrode layer is visible for each partition wall. For each first electrode layer, the thickness T1 is measured at two locations in each cross-sectional image, at the center of the length perpendicular to the direction in which the flow channels extend of the partition wall forming the first end face covered by the first electrode layer. The direction of the thickness is parallel to the direction in which the flow channels extend. Then, numerous cross-sectional images of the first electrode layer are obtained without bias from near the first end face of the heater element, and the thickness T1 of the first electrode layer is measured at a total of 10 or more locations. The average value of all measured thicknesses T1 is taken as the average thickness of the first electrode layer. The average thickness of the second electrode layer 102b is measured using the same procedure.

[0047] There is no particular limit to the lower limit of the volume resistivity of the first electrode layer 102a and the second electrode layer 102b at 25°C, but the range that is usually achievable is 1.0 × 10⁻⁶. -7 It is Ω·cm or greater. The upper limit of the volume resistivity of the first electrode layer 102a and the second electrode layer 102b at 25°C is 1.0 × 10⁻⁶, from the viewpoint of ensuring that current is sufficiently distributed across the plane and that the temperature distribution is uniform. -5 It is preferable that the value be Ω·cm or less, and 1.0 × 10 -6 Preferably, it should be Ω·cm or less, and 5.0 × 10 -7 It is more preferable that it be less than or equal to Ω·cm, and 3.0 × 10 -7 It is even more preferable that it be Ω·cm or less. Therefore, the range of volume resistivity of the first electrode layer 102a and the second electrode layer 102b at 25°C is, for example, 1.0 × 10⁻⁶. -7 Ω cm or more 1.0×10 -5 It can be less than or equal to Ω·cm. In this specification, the volume resistivity of the first electrode layer 102a and the second electrode layer 102b at 25°C is measured in accordance with JIS K6271:2008.

[0048] (1-3. First and second moisture-absorbing layers) The first moisture-absorbing layer 107a covers a portion of the outer surface of the first electrode layer 102a, and the second moisture-absorbing layer 107b covers a portion of the outer surface of the second electrode layer 102b. This makes it possible to suppress migration of metal components in the electrode layers that would cause short circuits between the electrode layers. The outer surface of the first electrode layer 102a refers to the surface opposite to the surface on which the first electrode layer 102a contacts the first end face 101a. The outer surface of the second electrode layer 102b refers to the surface opposite to the surface on which the second electrode layer 102b contacts the second end face 101b.

[0049] The reason why the first moisture-absorbing material-containing layer 107a covers "a portion" of the outer surface of the first electrode layer 102a is that the portion of the outer surface of the first electrode layer 102a to which the first terminal 109a is connected should not be covered by the first moisture-absorbing material-containing layer 107a, and therefore it does not cover the entire surface. Similarly, the reason why the second moisture-absorbing material-containing layer 107b covers "a portion" of the outer surface of the second electrode layer 102b is that the portion of the outer surface of the second electrode layer 102b to which the second terminal 109b is connected should not be covered by the second moisture-absorbing material-containing layer 107b, and therefore it does not cover the entire surface.

[0050] To enhance the short-circuit prevention effect, it is preferable that the first moisture-absorbing material-containing layer 107a covers 80% or more of the area of ​​the outer surface of the first electrode layer 102a where the first terminal 109a is not connected, more preferably 90% or more, and even more preferably 99% or more. Similarly, it is preferable that the second moisture-absorbing material-containing layer 107b covers 80% or more of the area of ​​the outer surface of the second electrode layer 102b where the second terminal 109b is not connected, more preferably 90% or more, and even more preferably 99% or more.

[0051] The first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b are preferably insulating. The areas near the first end face 101a and the second end face 101b are prone to the adhesion of foreign flying objects, and if these objects are conductive, they can cause short circuits. By making the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b insulating, short circuits caused by flying objects can be prevented. In this specification, the statement that the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b are insulating means that the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b each satisfy the following conditions regarding electrical resistance.

[0052] The coordinate value of the centroid O of the first end face 101a (second end face 101b) is set to 0, and the coordinate axis is taken in the direction from the centroid O toward the outer contour C of the first end face 101a (second end face 101b), with the coordinate value at the outer contour C set to 1.00R. Then, the electrical resistance at 25°C between two points on the outer surface of the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b) that are furthest apart between the centroid O and an arbitrary point D with coordinate value 0.90R is measured using the shunt method (see Figure 1A). The outer surface of the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b) refers to the surface opposite to the surface on which the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b) is in contact with the first electrode layer 102a (second electrode layer 102b). Next, point D is rotated 30° with the centroid O as the center of rotation, and the electrical resistance is measured in the same manner. In this way, point D is rotated 30° at a time, and the electrical resistance between the center of gravity O and point D is measured for one full rotation (12 locations). The lower limit of the electrical resistance obtained at the 12 locations is 1.0 × 10⁻¹⁰. 4 The first moisture-absorbing layer 107a (second moisture-absorbing layer 107b) is defined as insulating when its impedance is greater than or equal to Ω. Furthermore, if the first terminal 109a (second terminal 109b) exists between the line segment connecting point D at the rotated position and the centroid O, the measurement should be taken after further rotating point D to a position where the first terminal 109a (second terminal 109b) no longer exists.

[0053] The first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b have a lower limit of electrical resistance of 1.0 × 10 when measured using the procedure described above.5 Preferably, it is Ω or greater, 5.0 × 10 5 It is more preferable that the resistance be Ω or greater. No upper limit is set for the electrical resistance of the first moisture-absorbing material-containing layer 107a and the second moisture-absorbing material-containing layer 107b, but the range of electrical resistance when measured using the above procedure is 1.0 × 10⁻⁶. 5 Ω~1.0×10 7 It is usually Ω, and 2.0 × 10 5 Ω~1.0×10 6 It is typically Omega.

[0054] In this specification, a desiccant refers to a substance that, when left for one hour in an environment with room temperature (25°C) and relative humidity of 50%, can adsorb 5 g / g or more of water per gram of its dry mass. Preferably, the desiccant has the function of adsorbing moisture at -20 to 40°C and releasing it at a high temperature of 60°C or higher, preferably 70 to 180°C. When a desiccant has the function of adsorbing moisture at low temperatures and releasing it at high temperatures, the desiccant can be used many times by repeatedly applying and de-energizing it.

[0055] There are no particular restrictions on the type of moisture absorbent contained in the first moisture absorbent layer 107a and the second moisture absorbent layer 107b, but examples include silica gel, sepiolite, calcium oxide, diatomaceous earth, activated carbon, activated clay, zeolite, white carbon, calcium chloride, magnesium chloride, potassium acetate, disodium phosphate, sodium citrate, and superabsorbent polymers, crystalline aluminum silicate, and amorphous aluminum silicate. Among these, zeolite and amorphous aluminum silicate are preferred, and amorphous aluminum silicate is more preferred, because they can release moisture in relatively low temperature ranges. One type of moisture absorbent may be used alone, or two or more types may be used in combination. The above-mentioned moisture absorbents are examples and are not limited thereto.

[0056] The first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b may contain a binder. Both organic and inorganic binders are possible, but inorganic binders are preferred. There are no particular restrictions on the type of inorganic binder, but examples include alumina sol, silica sol, montmorillonite, boehmite, gamma alumina, and attapulgite. These may be used individually or in combination of two or more. Among these, alumina sol and silica sol are preferred, and silica sol is more preferred, because they make it easier to ensure adhesive strength.

[0057] The first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b may contain, in addition to the moisture-absorbing material, a functional material that has the function of adsorbing components to be removed from the air, such as carbon dioxide and / or organic gas components. In particular, it is preferable to contain a functional material that has the function of adsorbing carbon dioxide and / or organic gas components at -20 to 40°C and releasing them at a high temperature of 60°C or higher, preferably 70 to 180°C. When the functional material has the function of adsorbing components to be removed from the air at low temperatures and releasing them at high temperatures, the functional material can be used many times by repeatedly applying and de-energizing it.

[0058] Organic gas components in the air that may be targeted for removal include, for example, volatile organic compounds (VOCs) and odor components. Specific examples of harmful volatile components include ammonia, acetic acid, isovaleric acid, nonenal, formaldehyde, toluene, xylene, paradichlorobenzene, ethylbenzene, styrene, chlorpyrifos, di-n-butyl phthalate, tetradecane, di-2-ethylhexyl phthalate, diazinon, acetaldehyde, and N-methylcarbamate-2-(1-methylpropyl)phenyl.

[0059] Some of the moisture-absorbing materials mentioned above also possess these functions, and there is some overlap in the description, but examples of functional materials include zeolite, silica gel, activated carbon, alumina, silica, low-crystallinity clay, and amorphous aluminum silicate salt composites. The type of functional material should be appropriately selected according to the type of component to be removed. One type of functional material may be used alone, or two or more types may be used in combination.

[0060] The first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b may further contain a catalyst for purposes such as purifying the components to be removed or enhancing the capture function of the functional material (including the moisture absorber) for the components to be removed. The catalyst is preferably one that has the function of promoting oxidation-reduction reactions. Examples of catalysts with such functions include metal catalysts such as Pt, Pd, and Ag, and oxide catalysts such as CeO2 and ZrO2. The catalyst may be used alone or in combination of two or more types.

[0061] The average thickness of at least one, preferably both, of the first moisture-absorbing material-containing layer 107a and the second moisture-absorbing material-containing layer 107b can be, for example, 10 μm or more and 500 μm or less, although this is not limited to these two layers. The advantage of ensuring insulation and sufficient moisture absorption capacity is obtained when the lower limit of the average thickness of at least one, preferably both, of the first moisture-absorbing material-containing layer 107a and the second moisture-absorbing material-containing layer 107b is 10 μm or more, preferably 30 μm or more, and more preferably 50 μm or more. The advantage of reducing the rigidity of the moisture-absorbing material-containing layer and making it less likely to peel off is obtained when the upper limit of the average thickness of at least one, preferably both, of the first moisture-absorbing material-containing layer 107a and the second moisture-absorbing material-containing layer 107b is 500 μm or less, preferably 300 μm or less, and more preferably 200 μm or less.

[0062] The average thickness of the first moisture-absorbing material-containing layer 107a is measured by the following procedure. First, a cross-sectional image of the first moisture-absorbing material-containing layer is obtained at approximately 50x magnification using a scanning electron microscope or the like. The cross-section is parallel to the direction in which the flow channels of the honeycomb structure extend. In the cross-sectional image, as illustrated in the partially enlarged view in Figure 1B, the first moisture-absorbing material-containing layer is visible at each partition wall. For each first moisture-absorbing material-containing layer, the thickness T2 is measured at two locations per cross-sectional image, at the center of the length perpendicular to the direction in which the flow channels of the partition wall forming the first end face indirectly covered by the said first moisture-absorbing material-containing layer extend. The thickness direction is parallel to the direction in which the flow channels extend. Then, numerous cross-sectional images of the first moisture-absorbing material-containing layer are obtained without bias from near the first end face of the heater element, and the thickness T2 of the first moisture-absorbing material-containing layer is measured at a total of 10 or more locations. The average value of all measured thicknesses T2 is taken as the average thickness of the first moisture-absorbing material-containing layer. The average thickness of the second moisture-absorbing material-containing layer 107b is measured using the same procedure.

[0063] The first moisture-absorbing material-containing layer 107a preferably covers not only the outer surface of the first electrode layer 102a, but also part or all of other exposed surfaces of the first electrode layer 102a (for example, surfaces parallel to the thickness direction of the first electrode layer 102a), and more preferably covers all of them. Similarly, the second moisture-absorbing material-containing layer 107b preferably covers not only the outer surface of the second electrode layer 102b, but also part or all of other exposed surfaces of the second electrode layer 102b (for example, surfaces parallel to the thickness direction of the second electrode layer 102b), and more preferably covers all of them.

[0064] (1-4. Terminals) The first terminal 109a is connected to the portion of the outer surface of the first electrode layer 102a that is not covered by the first moisture-absorbing material-containing layer 107a. The second terminal 109b is connected to the portion of the outer surface of the second electrode layer 102b that is not covered by the second moisture-absorbing material-containing layer 107b. It is preferable that the first terminal 109a and the second terminal 109b are arranged on the outer periphery.

[0065] The connection method between the first electrode layer 102a and the first terminal 109a, and between the second electrode layer 102b and the second terminal 109b, is not particularly limited as long as they are electrically conductive, and can be connected by welding, brazing, or mechanical contact, for example. The material of the first terminal 109a and the second terminal 109b is not particularly limited, but can be metal, for example. As the metal, elemental metals and alloys can be used, but from the viewpoint of selecting a material that is less prone to oxidation in high humidity environments, less prone to migration and galvanic corrosion even under wet conditions, and easy to join with the electrodes, it is preferable to include one or more selected from pure aluminum, aluminum alloys, and stainless steel, for example, they can be made of pure aluminum, aluminum alloys, or stainless steel. In addition, alloys containing at least one selected from the group consisting of Cr, Fe, Co, Ni, Cu, and Ti can also be used, and among these, Fe-Ni alloys and phosphor bronze can be suitably used. From the viewpoint of avoiding galvanic corrosion, it is preferable that the terminals be made of a material similar to the electrode layer on the end face. Exemplarily, it is preferable that both the electrode layer and the terminals are made of pure aluminum and / or aluminum alloys.

[0066] The shapes of the first terminal 109a and the second terminal 109b are not limited, but can be, for example, flat. In that case, the thickness of the terminals is not limited, but can be, for example, 0.1 to 4 mm, and preferably 0.3 to 2 mm.

[0067] Since the first terminal 109a is connected to the first electrode layer 102a, there is no particular limit to the area of ​​the portion of the first end face 101a that is (indirectly) covered by the first terminal 109a. However, if the first terminal 109a is too small, it becomes difficult to connect a power-carrying component to the first terminal 109a. Conversely, if the first terminal 109a is too large, the area that blocks the opening of the cell 104 increases, and the airflow rate that can be supplied to the heater element 100 decreases. Therefore, the lower limit of the ratio of the area covered by the first terminal 109a to the area of ​​the first end face 101a is preferably 0.5% or more, more preferably 1% or more, and even more preferably 2% or more. Also, the upper limit of the ratio of the area covered by the first terminal 109a to the area of ​​the first end face 101a is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less. Therefore, the ratio of the area covered by the first terminal 109a to the area of ​​the first end face 101a can be, for example, 0.5% or more and 10% or less. The same applies to the ratio of the area covered by the second terminal 109b to the area of ​​the second end face 101b.

[0068] There is no particular limit to the lower limit of the volume resistivity of the first terminal 109a and the second terminal 109b at 25°C, but the normally achievable range is 1.0 × 10⁻⁶. -7 It is Ω·cm or greater. The upper limit of the volume resistivity of the first terminal 109a and the second terminal 109b at 25°C is 1.0 × 10⁻⁶, from the viewpoint of reducing heat generation and energy loss at the terminals. -6 Preferably, it should be Ω·cm or less, and 5.0 × 10 -7 It is preferable that it be Ω·cm or less, and 3.0 × 10 -7 It is more preferable that it be Ω·cm or less, and 2.0 × 10 -7 It is even more preferable that it be Ω·cm or less. Therefore, the range of volume resistivity of the first terminal 109a and the second terminal 109b at 25°C is, for example, 1.0 × 10⁻⁶. -7 Ω cm or more 1.0×10 -6It can be less than or equal to Ω·cm. In this specification, the volume resistivity of the first terminal 109a and the second terminal 109b at 25°C is measured in accordance with JIS K6271:2008.

[0069] (1-5. Third and fourth moisture-absorbing layer) The third moisture-absorbing layer 111a covers a portion of the outer surface of the first terminal 109a, and the fourth moisture-absorbing layer 111b covers a portion of the outer surface of the second terminal 109b. This makes it possible to suppress the migration of metal components in the terminals that causes short circuits. The outer surface of the first terminal 109a refers to the surface opposite to the surface on which the first terminal 109a contacts the first electrode layer 102a. The outer surface of the second terminal 109b refers to the surface opposite to the surface on which the second terminal 109b contacts the second electrode layer 102b.

[0070] The reason why the third moisture-absorbing layer 111a covers "part" of the outer surface of the first terminal 109a is that the portion of the outer surface of the first terminal 109a to which the conductive component 105a is connected should not be covered by the third moisture-absorbing layer 111a, and therefore it does not cover the entire surface. Similarly, the reason why the fourth moisture-absorbing layer 111b covers "part" of the outer surface of the second terminal 109b is that the portion of the outer surface of the second terminal 109b to which the conductive component 105b is connected should not be covered by the fourth moisture-absorbing layer 111b, and therefore it does not cover the entire surface.

[0071] To enhance the short-circuit prevention effect, it is preferable that the third moisture-absorbing layer 111a covers 80% or more of the area of ​​the outer surface of the first terminal 109a where the conductive component 105a is not connected, more preferably 90% or more, and even more preferably 99% or more. Similarly, it is preferable that the fourth moisture-absorbing layer 111b covers 80% or more of the area of ​​the outer surface of the second terminal 109b where the conductive component 105b is not connected, more preferably 90% or more, and even more preferably 99% or more.

[0072] The third moisture-absorbing layer 111a and the fourth moisture-absorbing layer 111b are preferably insulating for the same reasons as the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b. The third moisture-absorbing layer 111a and the fourth moisture-absorbing layer 111b are said to be insulating if they satisfy the following conditions regarding electrical resistance.

[0073] The electrical resistance at 25°C between any two points 3 mm apart on the outer surface of the third moisture-absorbing layer 111a (fourth moisture-absorbing layer 111b) is measured by the shunt method. However, the two points are selected such that no conductive component 105a is present between the line segment connecting them. When measurements are taken at three different locations, the lower limit of the obtained electrical resistance is 1.0 × 10⁻⁶. 4 The third moisture-absorbing layer 111a (fourth moisture-absorbing layer 111b) is defined as insulating when its impedance is greater than or equal to Ω.

[0074] The third moisture-absorbing layer 111a and the fourth moisture-absorbing layer 111b have a lower limit of electrical resistance of 1.0 × 10 when measured using the procedure described above. 5 Preferably, it is Ω or greater, 5.0 × 10 5 It is more preferable that the resistance be Ω or greater. While no upper limit is specifically set for the electrical resistance of the third moisture-absorbing layer 111a and the fourth moisture-absorbing layer 111b, the range of electrical resistance when measured using the above procedure is 5.0 × 10⁻⁶. 5 Ω~1.0×10 7 It is usually Ω, and 1.0 × 10 6 Ω~5.0×10 6 It is typically Omega.

[0075] The types of moisture absorbers contained in the third moisture absorber-containing layer 111a and the fourth moisture absorber-containing layer 111b are as described in the description of the first moisture absorber-containing layer 107a and the second moisture absorber-containing layer 107b, including preferred embodiments.

[0076] The third moisture-absorbing layer 111a and the fourth moisture-absorbing layer 111b may contain a binder. The binder is as described in the description of the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b, including preferred embodiments.

[0077] The third moisture-absorbing layer 111a and the fourth moisture-absorbing layer 111b may contain, in addition to the moisture-absorbing material, a functional material that has the function of adsorbing components to be removed from the air, such as carbon dioxide and / or organic gas components. The functional material is as described in the description of the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b, including preferred embodiments.

[0078] The third moisture-absorbing layer 111a and the fourth moisture-absorbing layer 111b may further contain a catalyst for purposes such as purifying the components to be removed or enhancing the capture function of the functional material (including the moisture absorber) for the components to be removed. The catalyst is as described in the description of the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b, including preferred embodiments.

[0079] The average thickness of the third moisture-absorbing material-containing layer 111a and the fourth moisture-absorbing material-containing layer 111b is not limited, but can be, for example, 10 μm or more and 500 μm or less. Having a lower limit of the average thickness of the third moisture-absorbing material-containing layer 111a and the fourth moisture-absorbing material-containing layer 111b of 10 μm or more, preferably 20 μm or more, and more preferably 30 μm or more, provides the advantage of ensuring both insulation and sufficient moisture absorption capacity. Having an upper limit of the average thickness of the third moisture-absorbing material-containing layer 111a and the fourth moisture-absorbing material-containing layer 111b of 500 μm or less, preferably 300 μm or less, and more preferably 200 μm or less, provides the advantage of reducing the rigidity of the moisture-absorbing material-containing layer, making it less prone to peeling.

[0080] The average thickness of the third moisture-absorbing layer 111a is determined by taking the average of the thicknesses of five or more arbitrary locations in the third moisture-absorbing layer using the cross-sectional method in accordance with JIS K 5600-1-7 (2014). The average thickness of the fourth moisture-absorbing layer 111b is measured using the same procedure.

[0081] The third moisture-absorbing layer 111a preferably covers not only the outer surface of the first terminal 109a, but also part or all of other exposed surfaces of the first terminal 109a (for example, surfaces parallel to the thickness direction when the first terminal 109a is flat), and more preferably covers all of them. Similarly, the fourth moisture-absorbing layer 111b preferably covers not only the outer surface of the second terminal 109b, but also part or all of other exposed surfaces of the second terminal 109b (for example, surfaces parallel to the thickness direction when the second terminal 109b is flat), and more preferably covers all of them.

[0082] (1-6.Fifth hygroscopic material containing layer) From the viewpoint of increasing the overall water absorption capacity of the heater element 100, it is preferable to have a fifth moisture-absorbing material-containing layer 113 that covers part or all of the surface of the partition wall 106 that forms the flow path inside the cell 104. A higher water absorption capacity can enhance the short-circuit prevention effect and also improve the indoor environment when the purpose is humidity control.

[0083] To enhance the short-circuit prevention effect and the indoor environment improvement effect, it is preferable that the fifth moisture-absorbing material-containing layer 113 covers 80% or more of the surface area of ​​the partition wall 106 that forms the flow path inside the cell 104, more preferably 90% or more, and even more preferably 99% or more. The percentage of the surface area of ​​the partition wall 106 that forms the flow path inside the cell 104 that is covered by the fifth moisture-absorbing material-containing layer 113 is measured by the following procedure. (1) Cut out a cross section from the heater element 100 that passes through the centroid O of the first end face 101a (second end face 101b) and is parallel to the direction in which the cell 104 extends. (2) The obtained cross-section is imaged, and by image analysis, the ratio of the length of the portion covered by the fifth moisture-absorbing material-containing layer 113 to the length of the surface of the partition wall 106 that forms the flow channel inside the cell 104 is determined for each cell 104. The average of the ratio measured for all cells 104 in the said cross-section is considered to be the ratio of the area covered by the fifth moisture-absorbing material-containing layer 113 to the surface area of ​​the partition wall 106 that forms the flow channel inside the cell 104. As for the image analysis, a method can be employed in which the brightness of each pixel constituting the fifth moisture-absorbing material-containing layer and the partition wall is measured on the image obtained by taking a picture with an optical microscope (magnification 50x), and the average value is used as a threshold to perform binarization processing to distinguish the region of the fifth moisture-absorbing material-containing layer and the partition wall. The length of the portion of the partition wall covered by the fifth moisture-absorbing material-containing layer can be identified, and the ratio of the length of the portion covered by the fifth moisture-absorbing material-containing layer can be determined by dividing it by the length of the cell (length of the honeycomb structure).

[0084] The fifth moisture-absorbing layer 113 is preferably insulating for the same reasons as the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b. The fifth moisture-absorbing layer 113 is considered insulating if it satisfies the following conditions.

[0085] A cross section parallel to the direction in which the flow path of the honeycomb structure extends is cut from the heater element 100 to expose the fifth moisture-absorbing material-containing layer 113 that covers the surface of the partition wall 106. For the surface of the fifth moisture-absorbing material-containing layer 113 covering any one cell 104, the electrical resistance at 25°C between any five pairs of points separated by a distance of 3 mm in the direction of extension of the cell 104 is measured by the shunt method. If the obtained electrical resistance is 1.0 × 10⁻¹⁰ 4 The fifth moisture-absorbing layer 113 covering the cell is defined as having insulating properties when the impedance is Ω or greater. The same measurement can be taken for the fifth moisture-absorbing layer 113 covering other cells, but if it is clear that the material forming the fifth moisture-absorbing layer 113 is substantially the same, the measurement may be omitted as the results will be the same.

[0086] The fifth moisture-absorbing layer 113 has a lower limit of electrical resistance of 1.0 × 10 when measured using the procedure described above. 5 Preferably, it is Ω or greater, 5.0 × 10 5 It is more preferable that the resistance be Ω or greater. While no upper limit is specifically set for the electrical resistance of the fifth moisture-absorbing material-containing layer 113, the range of electrical resistance when measured using the above procedure is 5.0 × 10⁻⁶. 5 Ω~1.0×10 7 It is usually Ω, and 1.0 × 10 6 Ω~5.0×10 6 It is typically Omega.

[0087] The type of moisture absorbent contained in the fifth moisture absorbent layer 113 is as described in the descriptions of the first moisture absorbent layer 107a and the second moisture absorbent layer 107b, including preferred embodiments.

[0088] The fifth moisture-absorbing material-containing layer 113 may contain a binder. The binder is as described in the description of the first moisture-absorbing material-containing layer 107a and the second moisture-absorbing material-containing layer 107b, including preferred embodiments.

[0089] The fifth moisture-absorbing material-containing layer 113 may contain, in addition to the moisture-absorbing material, a functional material that has the function of adsorbing components to be removed from the air, such as carbon dioxide and / or organic gas components. The functional material is as described in the description of the first moisture-absorbing material-containing layer 107a and the second moisture-absorbing material-containing layer 107b, including preferred embodiments.

[0090] The fifth moisture-absorbing material-containing layer 113 may further contain a catalyst for purposes such as purifying the components to be removed or enhancing the capture function of the functional material (including the moisture absorber) for the components to be removed. The catalyst is as described in the description of the first moisture-absorbing material-containing layer 107a and the second moisture-absorbing material-containing layer 107b, including preferred embodiments.

[0091] The average thickness of the fifth moisture-absorbing material-containing layer 113 is not limited, but can be, for example, 10 μm or more and 500 μm or less. Having a lower limit of the average thickness of the fifth moisture-absorbing material-containing layer 113 of 10 μm or more, preferably 20 μm or more, and more preferably 30 μm or more, provides the advantage of ensuring sufficient moisture absorption capacity. Having an upper limit of the average thickness of the fifth moisture-absorbing material-containing layer 113 of 500 μm or less, preferably 300 μm or less, and more preferably 200 μm or less, allows for a large opening area of ​​the cells, thus providing the advantage of keeping the airflow resistance low.

[0092] The average thickness of the fifth moisture-absorbing material containing layer 113 is measured by the following procedure. First, a cross-sectional image of the fifth moisture-absorbing material containing layer 113 is obtained at approximately 50x magnification using a scanning electron microscope or the like. The cross-section is parallel to the direction in which the flow channels of the honeycomb structure extend. In the cross-sectional image, as illustrated in the partially enlarged view of Figure 1B, two fifth moisture-absorbing material containing layers 113 are visible on either side of each partition. The thickness of each fifth moisture-absorbing material containing layer 113 is calculated by dividing the total cross-sectional area of ​​each fifth moisture-absorbing material containing layer 113 from the first end face 101a to the second end face 101b by the length of the partition covered by the fifth moisture-absorbing material containing layer from the first end face 101a to the second end face 101b. Then, multiple cross-sectional images of the fifth moisture-absorbing material containing layer 113 are obtained evenly from the heater element, and the thickness of five or more fifth moisture-absorbing material containing layers 113 is measured. The average thickness of all measured fifth moisture-absorbing material-containing layers 113 is defined as the average thickness of the fifth moisture-absorbing material-containing layers.

[0093] It should be noted that the classification of the various moisture-absorbing material-containing layers from the first to the fifth, as described above, is for convenience only. Therefore, it is not necessary for each layer to be formed independently, and there is no impediment to different classifications of moisture-absorbing material-containing layers being continuous, nor is there any impediment to different classifications of moisture-absorbing material-containing layers being formed simultaneously in a single process.

[0094] (1-7. Moisture absorption characteristics of heater elements) As described above, the heater element according to one embodiment of the present invention comprises, as appropriate, a third, fourth, and fifth moisture-absorbing material-containing layer, in addition to the first and second moisture-absorbing material-containing layers. The moisture absorption characteristics of the heater element depend on the total mass of moisture-absorbing material contained in these moisture-absorbing material-containing layers, with a larger amount of moisture-absorbing material resulting in a higher maximum water absorption capacity. From the viewpoint of the heater element exhibiting excellent moisture absorption performance, the lower limit of the maximum water absorption capacity (g) of the heater element per unit volume (1 liter) of the honeycomb structure is preferably 20 g / liter or more, more preferably 100 g / liter or more, and even more preferably 150 g / liter or more. Furthermore, from the viewpoint of ensuring a large opening area of ​​the cells to reduce ventilation resistance and reducing the rigidity of the moisture-absorbing material-containing layer to prevent peeling, the upper limit of the maximum water absorption (g) of the heater element per unit volume (1 liter) of the honeycomb structure is preferably 400 g / liter or less, more preferably 350 g / liter or less, and even more preferably 300 g / liter or less. The range of the maximum water absorption (g) of the heater element per unit volume (1 liter) of the honeycomb structure can be, for example, 20 g / liter or more and 400 g / liter or less.

[0095] The maximum water absorption capacity of the heater element is measured using the following procedure. Prepare a heater element with the frame (described later) removed. Next, dry this heater element at 180°C for at least 2 hours, then leave it in a constant temperature and humidity chamber at 25°C and a relative humidity of 90% or higher for 1 hour. Determine the amount of water absorbed by the heater element from the change in mass before and after. This amount of water absorbed is taken as the maximum water absorption capacity. Then, divide the maximum water absorption capacity (g) by the external dimensions (liters) of the honeycomb structure to calculate the maximum water absorption capacity per unit volume (g / liter). Furthermore, the maximum water absorption capacity of the heater element depends on the water absorption performance of the moisture absorbers contained in the third, fourth, and fifth moisture absorber layers, if those layers are present, in addition to the moisture absorbers contained in the first and second moisture absorber layers.

[0096] In the heater element according to the embodiment of the present invention, if the first region is defined as a portion with a length of 0.5 cm in the cell extension direction (direction of flow path extension) from the outer surface of the first moisture-absorbing material-containing layer toward the second end face, then in order to ensure excellent moisture absorption performance, the lower limit of the maximum water absorption amount (g) per unit volume (1 liter) of the first region is preferably 90 g / liter or more, more preferably 100 g / liter or more, and even more preferably 120 g / liter or more. The upper limit of the maximum water absorption amount (g) per unit volume (1 liter) of the first region is preferably 200 g / liter or less, more preferably 180 g / liter or less, and even more preferably 160 g / liter or less, in order to shorten the time of the regeneration process in which water is released and dried. Therefore, the range of the maximum water absorption amount (g) per unit volume (1 liter) of the first region can be, for example, 90 g / liter or more and 200 g / liter or less.

[0097] Similarly, in the heater element according to the embodiment of the present invention, if the second region is defined as a portion with a length of 0.5 cm in the cell extension direction (direction of flow path extension) from the outer surface of the second moisture-absorbing material-containing layer toward the first end face, the lower limit of the maximum water absorption (g) per unit volume (1 liter) of the second region is preferably 90 g / liter or more, more preferably 100 g / liter or more, and even more preferably 120 g / liter or more. The upper limit of the maximum water absorption (g) per unit volume (1 liter) of the second region is preferably 200 g / liter or less, more preferably 180 g / liter or less, and even more preferably 160 g / liter or less, in order to shorten the time of the regeneration process in which water is released and dried. Therefore, the range of the maximum water absorption (g) per unit volume (1 liter) of the second region can be, for example, 90 g / liter or more and 200 g / liter or less.

[0098] In this specification, the maximum water absorption of the first (second) region of the heater element is measured by the following procedure. Prepare a heater element with the frame (described later) removed. Next, remove the first (second) terminal from the heater element, and then cut and collect the first (second) region from the heater element. Dry the first (second) region at 180°C for at least 2 hours, then leave it in a constant temperature and humidity chamber at 25°C and a relative humidity of 90% or higher for 1 hour, and determine the water absorption of the first (second) region from the change in mass before and after. This water absorption is defined as the maximum water absorption. Then, divide the maximum water absorption (g) by the external dimensions (liters) of the first (second) region to calculate the maximum water absorption per unit volume (g / liter).

[0099] (1-8. Conductive Components) The first terminal 109a and the second terminal 109b are each capable of connecting to conductive components 105a and 105b, respectively. Examples of conductive materials constituting the conductive components 105a and 105b include stainless steel, aluminum, aluminum alloy, copper alloy, and copper. The connection method between the first terminal 109a and the conductive component 105a, and between the second terminal 109b and the conductive component 105b, is not particularly limited as long as they are electrically conductive; for example, they can be connected by welding, brazing, or mechanical contact. In one embodiment, the conductive components 105a and 105b may be the wire itself connecting the power source and the first terminal 109a (second terminal 109b), i.e., a copper wire, copper alloy wire, aluminum wire, aluminum alloy wire, or stainless steel wire. In another embodiment, the conductive components 105a and 105b may be intermediary components connecting the wire and the first terminal 109a (second terminal 109b). Intermediate components can be connected to the wires by any of the following methods, for example, welding, soldering, brazing, crimping, and bolting.

[0100] (2. Heater element assembly) A heater element according to one embodiment of the present invention may be provided as a heater element assembly held in a frame. The protective effect of the frame makes the heater element less susceptible to damage when installed in a ventilation passage, and also allows for a shape that is easy to install in an air conditioning system while ensuring electrical insulation from surrounding parts.

[0101] There are no particular restrictions on the frame that holds the heater element, but in one embodiment, the frame can be configured to hold the heater element from the first end face side and the second end face side. In another embodiment, the frame can be configured to hold the heater element from the outer circumferential surface side of the outer circumferential wall.

[0102] (2-1. Heater element assembly with end-face clamping frame) Figures 2A and 2B show an example of a heater element assembly comprising a frame 120 that clamps the heater element 100 from the first end face 101a side and the second end face 101b side. The frame 120 has a first frame portion 121 and a second frame portion 122 for clamping the heater element from the first end face 101a side and the second end face 101b side. The first frame portion 121 is a resin first frame portion 121 positioned on the first end face 101a side, and has a flange portion 121b positioned on the outer circumference side of the outer circumference contour C of the first end face 101a, and a holding portion 121a positioned on the inner circumference side of the outer circumference contour C of the first end face 101a, which applies pressure to at least a part of the outer circumference of the first end face 101a. The second frame portion 122 is a resin second frame portion 122 positioned on the second end face 101b side, and has a flange portion 122b positioned on the outer circumference side of the outer circumference contour C of the second end face 101b, and a holding portion 122a positioned on the inner circumference side of the outer circumference contour C of the second end face 101b, which applies pressure to at least a part of the outer circumference of the second end face 101b.

[0103] In this specification, the coordinate value of the centroid O of the first end face 101a (second end face 101b) is set to 0, and the coordinate axes are taken in the direction from the centroid O toward the outer contour C of the first end face 101a (second end face 101b). If the coordinate value at the outer contour C is set to 1.00R, then the set of points located between 0.90R and 1.00R is defined as the outer periphery of the first end face 101a (second end face 101b).

[0104] In one embodiment, the outer shape of the first frame portion 121 (second frame portion 122) is an annular shape. The specific shape and dimensions of the first frame portion 121 (second frame portion 122) should be designed to match the shape and dimensions of the first end face 101a (second end face 101b) of the heater element 100.

[0105] The retaining portion 121a (122a) may apply pressure to the first end face 101a (second end face 101b) on the inner side of the outer circumference, but if the retaining portion 121a (122a) expands, it becomes easier to obstruct the airflow entering and exiting the heater element 100. Therefore, it is preferable that the retaining portion 121a (122a) applies pressure only to the outer circumference of the first end face 101a (second end face 101b).

[0106] Furthermore, from the viewpoint of not obstructing the airflow into and out of the heater element 100, the area of ​​the portion of the first end face 101a (second end face 101b) that is pressurized by the holding portion 121a (122a) is preferably 10% or less, more preferably 8% or less, even more preferably 5% or less, even more preferably 2% or less, even more preferably 1.8% or less, and even more preferably 1.6% or less. Also, from the viewpoint of improving the holding performance with respect to the heater element 100, the area of ​​the portion of the first end face 101a (second end face 101b) that is pressurized by the holding portion 121a (122a) is preferably 1% or more, more preferably 1.2% or more, and even more preferably 1.4% or more. Therefore, the ratio of the area of ​​the first end face 101a (second end face 101b) that is subjected to pressure by the holding portion 121a (122a) to the total area of ​​the first end face 101a (second end face 101b) can be, for example, 1% or more and 10% or less.

[0107] The upper limit of the width W of the holding portion 121a (122a) is preferably 7 mm or less, more preferably 5 mm or less, and even more preferably 4 mm or less, from the viewpoint of not obstructing the flow of gas entering and leaving the heater element 100. The lower limit of the width W of the holding portion 121a (122a) is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more, from the viewpoint of improving the holding performance with respect to the heater element 100. Therefore, the range of the width W of the holding portion 121a (122a) can be, for example, 1 mm or more and 7 mm or less. Here, the width W of the holding portion 121a (122a) refers to the length of the holding portion 121a (122a) in the direction from the outer peripheral contour C of the first end face 101a (second end face 101b) toward the centroid O of the first end face 101a (second end face 101b).

[0108] The resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 is preferably soft to a certain extent so that the heater element 100 is not easily damaged. Accordingly, in one embodiment, the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 preferably has an upper limit of Rockwell hardness of 150 HRR or less, more preferably 130 HRR or less, and even more preferably 120 HRR or less, as measured in accordance with ASTM D785-2008 R15. In another embodiment, the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 preferably has an upper limit of Rockwell hardness of 120 HRM or less, more preferably 100 HRM or less, and even more preferably 90 HRM or less, as measured in accordance with ASTM D785-2008 R15. The resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 can satisfy the conditions relating to the upper limit of either the Rockwell hardness HRR or HRM described above, and it is desirable that both conditions be satisfied.

[0109] On the other hand, from the viewpoint of improving the holding performance for the heater element 100, it is desirable that the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 has a certain degree of hardness. Therefore, in one embodiment, the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 preferably has a Rockwell hardness lower limit of 70 HRR or higher, more preferably 80 HRR or higher, and even more preferably 90 HRR or higher, as measured in accordance with ASTM D785-2008 R15. In another embodiment, the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 preferably has a Rockwell hardness lower limit of 40 HRR or higher, as measured in accordance with ASTM D785-2008 R15. HIt is preferable that the hardness is RM or higher, more preferably 50 HRM or higher, and even more preferably 70 HRM or higher. The resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 can satisfy the conditions relating to the lower limit of either one of the Rockwell hardness HRR and HRM described above, and it is desirable that it satisfies both conditions.

[0110] Accordingly, in one embodiment, the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 has a Rockwell hardness range measured in accordance with ASTM D785-2008 R15, for example, between 70 HRR and 150 HRR. In another embodiment, the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 has a Rockwell hardness range of, for example, between 40 HRM and 120 HRM.

[0111] There are no particular restrictions on the type of resin that constitutes the first frame portion 121 and the second frame portion 122. However, from the viewpoint of heat resistance and corrosion resistance, it is preferable that the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 contains either or both of polyetheretherketone (PEEK) and polybutylene terephthalate (PBT). It is more preferable that the total content of polyetheretherketone (PEEK) and polybutylene terephthalate (PBT) be 80% by mass or more, even more preferable that it be 90% by mass or more, and it may even be 100% by mass.

[0112] The resins constituting the first frame portion 121 and the second frame portion 122 are preferably heat-resistant. Therefore, the resins constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 are preferably such that the lower limit of the load deflection temperature measured in accordance with JIS K7191-1:2015 is 145°C or higher, more preferably 160°C or higher, and even more preferably 180°C or higher. There is no particular upper limit set for the load deflection temperature, but from the viewpoint of availability, it is usually 300°C or lower, and typically 250°C or lower. Therefore, the resins constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 have a load deflection temperature range of, for example, 145°C to 300°C.

[0113] The resins constituting the first frame portion 121 and the second frame portion 122 are preferably made up of resins with high melting points so as not to melt when heated. Therefore, the resins constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 preferably have a lower limit of melting point of 250°C or higher, more preferably 280°C or higher, and even more preferably 300°C or higher. There is no particular upper limit set for the melting point, but from the viewpoint of availability, it is usually 400°C or lower, and typically 350°C or lower. Therefore, the resins constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 have a melting point range of, for example, 250°C or more and 400°C or less.

[0114] In this specification, the melting point of a resin refers to the lowest temperature at which an endothermic peak due to melting is observed when measured using TG-DTA (thermogravimetry - differential thermal analysis).

[0115] The resins constituting the first frame portion 121 and the second frame portion 122 are preferably low in thermal conductivity to reduce heat loss. Therefore, the resins constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 are preferably such that the upper limit of their thermal conductivity at 25°C, measured in accordance with JIS R1611:2010, is 0.5 W / m / K or less, more preferably 0.3 W / m / K or less, and even more preferably 0.2 W / m / K or less. There is no particular lower limit set for this thermal conductivity, but from the viewpoint of availability, it is usually 0.1 W / m / K or more, and typically 0.15 W The thermal conductivity is 0.1 W / m / K or higher. Therefore, the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 has a thermal conductivity in the range of, for example, 0.1 W / m / K or more and 0.5 W / m / K or less.

[0116] The resins constituting the first frame portion 121 and the second frame portion 122 are preferably insulating in order to suppress short circuits. Therefore, the resins constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 have a lower limit of volume resistivity at 25°C measured in accordance with the bridge method of JIS C 2139:2008 of 1.0 × 10⁻⁶. 16 It is preferable that the value be Ω·cm or greater, and 2.0 × 10 16 Ω·cm Preferably, it is 5.0 × 10 16 Ω·cm The above is more preferable. There is no specific upper limit set for volume resistivity, but from the standpoint of availability, it is usually 1.0 × 10⁻⁶. 18 Ω·cm The following is typical, typically 1.0 × 10⁻⁶ 17 Ω·cm The following applies. Therefore, the resin constituting at least one, preferably both, of the first frame portion 121 and the second frame portion 122 has a volume resistivity in the range of, for example, 1.0 × 10⁻⁶. 16 Ω cm or more 1.0×10 18 Ω·cm The following applies:

[0117] The retaining portion 121a (122a) may apply pressure directly to the first end face 101a (second end face 101b), but it is preferable to apply pressure indirectly via the cushioning material 127. By applying pressure indirectly to the first end face 101a (second end face 101b) via the cushioning material 127, the first end face 101a (second end face 101b) becomes less susceptible to damage. Furthermore, the cushioning material 127 can deform in accordance with the thermal deformation of the heater element 100, thereby easing thermal stress. This makes it possible to suppress the occurrence of cracks in the heater element 100.

[0118] The thickness of the cushioning material 127 in the compression direction, when compressed by the pressure applied by the holding portion 121a (122a), is preferably 0.5 mm or more at the lower limit, more preferably 1.0 mm or more, and even more preferably 2.0 mm or more, from the viewpoint of ensuring sufficient deformation allowance to obtain a sufficient cushioning effect. The thickness of the cushioning material 127 in the compression direction, when compressed by the pressure applied by the holding portion 121a (122a), is preferably 7.0 mm or less at the upper limit, more preferably 5.0 mm or less, and even more preferably 4.0 mm or less, from the viewpoint of ensuring sufficient holding surface pressure for the heater element and holding the heater element without damaging it. Therefore, the range of the thickness of the cushioning material 127 in the compression direction, when compressed by the pressure applied by the holding portion 121a (122a), can be, for example, 0.5 mm or more and 7.0 mm or less.

[0119] The lower limit of the pressure that the cushioning material 127 receives from the holding portion 121a (122a) is preferably 0.002 MPa or higher, and more preferably 0.005 MPa or higher. The upper limit of the pressure that the cushioning material 127 receives from the holding portion 121a (122a) is preferably 0.2 MPa or lower, and more preferably 0.1 MPa or lower. Therefore, the pressure that the cushioning material 127 receives from the holding portion 121a (122a) is preferably, for example, 0.002 MPa to 0.2 MPa, and more preferably 0.005 MPa to 0.1 MPa. The pressure that the cushioning material 127 receives from the holding portion 121a (122a) can be determined from the Young's modulus and displacement of the cushioning material 127.

[0120] From the viewpoint of ensuring sufficient holding surface pressure against the honeycomb heater element, the Young's modulus of the cushioning material 127 is preferably 0.05 MPa or higher at the lower limit, more preferably 0.06 MPa or higher, and even more preferably 0.1 MPa or higher. From the viewpoint of ensuring sufficient deformation allowance to obtain a sufficient cushioning effect, the Young's modulus of the cushioning material 127 is preferably 0.3 MPa or lower at the upper limit, more preferably 0.25 MPa or lower, and even more preferably 0.2 MPa or lower. Therefore, the range of the Young's modulus of the cushioning material 127 can be, for example, 0.05 MPa or higher and 0.3 MPa or lower.

[0121] The Young's modulus of the cushioning material 127 is determined from the relationship between surface pressure and thickness change when a sheet-like cushioning material is compressed by gradually applying surface pressure.

[0122] There are no particular restrictions on the type of material that constitutes the cushioning material 127, but from the viewpoint of ensuring sufficient deformation allowance, it is preferable that it be made of rubber, and more preferably of rubber sponge. Sponge means a porous material. The rubber and rubber sponge can contain various types of rubber such as natural rubber, styrene-butadiene rubber, butadiene rubber, chloroprene rubber, ethylene-propylene rubber, butyl rubber, fluororubber, acrylonitrile-butadiene rubber, silicone rubber, isoprene rubber, urethane rubber, chlorosulfonated polyethylene, hydrogenated nitrile rubber, epichlorohydrin rubber, acrylic rubber, ethylene acrylic rubber, norbornene rubber, and these may be contained individually or in a mixture of two or more types. Among these, it is more preferable that the cushioning material 127 be made of silicone rubber sponge with silicone rubber as the main component (preferably 60% by mass or more, more preferably 80% by mass or more).

[0123] In one embodiment, the first frame portion 121 and the second frame portion 122 can be provided separately from each other. In this case, the first frame portion 121 and the second frame portion 122 can be connected by a fastener 124. Connecting them with a fastener 124 has the advantage of making it easier to adjust the pressure that the holding portion 121a (122a) applies to the first end face 101a (second end face 101b). The fastener 124 can be fixed to the flange portion 121b (flange portion 122b). The fastener 124 is not limited to a combination of bolts and nuts. The first frame portion 121 and the second frame portion 122 may be provided with a recess 125 for accommodating the fastener 124. Providing a recess 125 makes it less likely for the fastener 124 to come off unintentionally. The number and position of the fasteners 124 connecting the first frame portion 121 and the second frame portion 122 can be set appropriately to stably hold the heater element 100, but as an example, it is preferable to install 4 to 8 fasteners at equal intervals in the circumferential direction of the flange portion 121b (flange portion 122b) when viewing the heater element assembly from the first end face 101a (second end face 101b) side (see Figure 2A).

[0124] When the first frame portion 121 and the second frame portion 122 are separated from each other, other methods for joining them include, but are not limited to, a method of joining them by a fitting structure and a method of joining them by adhesive.

[0125] Figures 3A and 3B show another example of a heater element assembly comprising a frame 120 that clamps the heater element 100 from the first end face 101a side and the second end face 101b side. The holding portion 121a of the first frame portion 121 of the frame 120 shown in Figures 3A and 3B has a portion that presses the first terminal 109a toward the first end face 101a. Similarly, the holding portion 122a of the second frame portion 122 of the frame 120 shown in Figures 3A and 3B has a portion that presses the second terminal 109b toward the second end face 101b.

[0126] The holding portion 121a (holding portion 122a) has a part that presses the first terminal 109a (second terminal 109b) toward the first end face 101a (second end face 101b), thereby preventing the first terminal 109a (second terminal 109b) from falling off. In addition, there is the advantage of improved conductivity between the first terminal 109a (second terminal 109b) and the first electrode layer 102a (second electrode layer 102b).

[0127] To enhance the effect of preventing the first terminal 109a from falling off, it is preferable that the holding portion 121a of the first frame portion 121 has a portion 126a that protrudes locally toward the inner circumference, and that this protruding portion 126a constitutes at least a part of the portion that presses the first terminal 109a toward the first end face 101a. Similarly, to enhance the effect of preventing the second terminal 109b from falling off, it is preferable that the holding portion 122a of the second frame portion 122 has a portion 126b that protrudes locally toward the inner circumference, and that this protruding portion 126b constitutes at least a part of the portion that presses the second terminal 109b toward the second end face 101b.

[0128] Since the holding portion 121a (holding portion 122a) only protrudes locally toward the inner circumference, it is possible to reduce the area that covers the opening of the cell 104. When the portion 126a (126b) that protrudes locally toward the inner circumference in order to press the first terminal 109a (second terminal 109b) toward the first end face 101a (second end face 101b) is observed from the first end face 101a (second end face 101b) side (see Figure 3A), the upper limit of the ratio that the area of ​​the locally protruding portion 126a (126b) (if there are multiple locally protruding portions 126a (126b), this refers to the total area of ​​those portions) occupies relative to the area of ​​the first end face 101a (second end face 101b) is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. On the other hand, from the viewpoint of enhancing the effect of preventing the first terminal 109a (second terminal 109b) from falling off, the lower limit of the ratio of the area of ​​the locally protruding portion 126a (126b) to the area of ​​the first end face 101a (second end face 101b) is preferably 0.5% or more, more preferably 1% or more, and even more preferably 2% or more. Therefore, the range of the ratio of the area of ​​the locally protruding portion 126a (126b) to the area of ​​the first end face 101a (second end face 101b) can be, for example, 0.5% or more and 10% or less.

[0129] In addition, the components in the heater element assemblies shown in Figures 3A and 3B that are represented by the same reference numerals as those in Figures 2A and 2B are the same as those described for the heater element assemblies in Figures 2A and 2B, so their explanation will be omitted.

[0130] (2-2. Heater element assembly with outer surface-holding frame) Figures 4A and 4B show an example of a heater element assembly comprising a frame 140 that holds the heater element 100 from the outer surface side of the outer wall 103. The frame 140 has a resin first frame portion 141 with an inner surface 141i that fits onto the outer surface 103e of the outer wall 103 of the honeycomb structure via a cushioning material 150. With this configuration, the frame 140 can hold the heater element 100 while suppressing damage to the honeycomb structure. Furthermore, the cushioning material 150 can deform in accordance with the thermal deformation of the heater element 100, thereby relieving thermal stress. This makes it possible to suppress the occurrence of cracks in the heater element 100.

[0131] From the viewpoint of stably holding the heater element 100 and enhancing the protective performance for the heater element 100, it is preferable that the frame 140 has a resin first frame portion 141 having an inner circumferential surface 141i that fits onto the entire outer circumferential surface 103e of the outer circumferential wall 103 of the honeycomb structure portion via a cushioning material 150.

[0132] In one embodiment, the frame 140 shown in Figures 4A and 4B can be provided as a single cylindrical piece. Alternatively, the frame 140 may be formed by connecting two separate parts. When the frame 140 is divided into parts, methods for joining the two parts are not limited to, but include, for example, joining them with fasteners, joining them with a fitting structure, and joining them with an adhesive.

[0133] The frame 140 shown in Figures 4A and 4B may be formed by connecting a pair of split members 140a and 140b from a direction perpendicular to the direction in which the flow channels of the honeycomb structure extend. Figure 4C shows the pair of split members 140a and 140b approaching each other from a direction perpendicular to the direction in which the flow channels of the honeycomb structure extend, with the heater element 100 in between.

[0134] Figure 4A, a schematic partially enlarged cross-sectional view, shows how a pair of split members 140a and 140b are connected by a connecting part 144 having a fitting structure. The illustrated connecting part 144 has a press-fit type convex part 144a and a concave part 144b. When the convex part 144a is pressed into the concave part 144b while elastically deforming it, the connected state is maintained by the restoring force of the convex part 144a and the concave part 144b. The connecting part 144 can have a snap-fit ​​type or other fitting structure in addition to the press-fit type. It is preferable to sandwich a cushioning material 145 between the pair of split members 140a and 140b. The cushioning material 145, compressed by being sandwiched between the two, acts as a spring through elastic deformation, preventing the connection between the pair of split members 140a and 140b from loosening.

[0135] Figures 5A and 5B show another example of a heater element assembly comprising a frame 140 that holds the heater element 100 from the outer circumferential surface side of the outer circumferential wall 103. The frame 140 shown in Figures 5A and 5B differs from the frame 140 shown in Figures 4A and 4B in that, in addition to the first frame portion 141, it further comprises a second frame portion 142 that extends inward from the outer circumferential contour C of the first end face 101a and surrounds at least a portion of the outer circumferential part of the first end face 101a, and a third frame portion 143 that is disposed inward from the outer circumferential contour C of the second end face 101b and surrounds at least a portion of the outer circumferential part of the second end face 101b. The second frame portion 142 and the third frame portion 143 can be extended from the first frame portion 141. The second frame section 142 and the third frame section 143 can also function as baffles to prevent gas bypass flow from occurring in areas where the buffer material 150 is omitted, such as when the heater element 100 has corners.

[0136] The frame 140 having a second frame portion 142 and a third frame portion 143 provides the effect of preventing the heater element 100 from moving away from the frame 140 in the direction extending the flow path. The second frame portion 142 (third frame portion 143) does not have to contact the surface of the heater element 100 on the first end face 101a (second end face 101b) side, but it is preferable to have a portion that presses the first terminal 109a (second terminal 109b) toward the first end face 101a (second end face 101b). In that case, the second frame portion 142 (third frame portion 143) may be configured to press the first terminal 109a (second terminal 109b) toward the first end face 101a (second end face 101b) via a cushioning material 129.

[0137] The second frame portion 142 (third frame portion 143) may partially surround the outer periphery of the first end face 101a (second end face 101b) by having one or more locations protrude locally inward, as shown in Figure 5A. When the second frame portion 142 (third frame portion 143) is installed in multiple locations by having localized protrusions inward, it is preferable to install 4 to 8 locations at equal intervals in the circumferential direction of the first end face 101a (second end face 101b) when viewing the heater element assembly from the first end face 101a (second end face 101b) side, and / or symmetrically with respect to the centroid O as the center of symmetry (see Figure 5A). Alternatively, the second frame portion 142 (third frame portion 143) may surround the entire outer periphery of the first end face 101a (second end face 101b), as shown in Figure 5C.

[0138] The larger the proportion of the outer surface area of ​​the first terminal 109a (second terminal 109b) that is pressed toward the first end face 101a (second end face 101b) by the second frame portion 142 (third frame portion 143), the greater the effect of preventing the first end face 101a (second end face 101b) from falling off. For this reason, the lower limit of this proportion of area is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more. On the other hand, the smaller the proportion of this area, the easier it is to secure space for the conductive components and to join the conductive components 105a (105b). For this reason, the upper limit of this proportion of area is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less. Therefore, the range of this proportion of area can be, for example, 10 to 80%.

[0139] The upper limit of the width Y of the region where the second frame portion 142 (third frame portion 143) surrounds the first end face 101a (second end face 101b) is preferably 10 mm or less, more preferably 7 mm or less, and even more preferably 5 mm or less, from the viewpoint of not obstructing the flow of gas entering and leaving the heater element 100. The lower limit of the width Y of the region where the second frame portion 142 (third frame portion 143) surrounds the first end face 101a (second end face 101b) is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more, from the viewpoint of improving the holding performance with respect to the heater element 100. Therefore, the range of the width Y of the region where the second frame portion 142 (third frame portion 143) surrounds the first end face 101a (second end face 101b) can be, for example, 1 mm or more and 10 mm or less. Here, the width Y of the region enclosed by the second frame portion 142 (third frame portion 143) to the first end face 101a (second end face 101b) represents the length of the second frame portion 142 (third frame portion 143) in the direction from the outer circumferential contour C of the first end face 101a (second end face 101b) toward the centroid O of the first end face 101a (second end face 101b).

[0140] When the second frame portion 142 (third frame portion 143) is observed from the first end face 101a (second end face 101b) side (see Figure 5A), the upper limit of the ratio of the area of ​​the second frame portion 142 (third frame portion 143) (if there are multiple second frame portions 142 (third frame portion 143), this refers to the total area of ​​those portions) to the area of ​​the first end face 101a (second end face 101b) is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less, from the viewpoint of not obstructing the flow of gas entering and leaving the heater element 100. On the other hand, from the viewpoint of improving the holding performance of the heater element 100, the lower limit of the ratio of the area of ​​the second frame portion 142 (third frame portion 143) to the area of ​​the first end face 101a (second end face 101b) is preferably 0.5% or more, more preferably 1% or more, and even more preferably 2% or more. Therefore, the range of the ratio in which the area of ​​the second frame portion 142 (third frame portion 143) occupies the area of ​​the first end face 101a (second end face 101b) can be, for example, 0.5% or more and 10% or less.

[0141] The frame 140 shown in Figures 5A and 5B is preferably formed by connecting two parts that are divided from each other. This is to facilitate the work of housing the heater element 100 in the frame 140, given that the frame 140 has a second frame portion 142 and a third frame portion 143. When the frame 140 is divided from each other, methods for joining the two parts are not limited to, but include, for example, joining by fasteners, joining by a fitting structure, and joining by adhesive. The frame 140 shown in Figures 5A and 5B is formed by connecting a pair of split members 140a and 140b from a direction perpendicular to the direction in which the flow path of the honeycomb structure extends. A specific example of the fitting structure is shown in Figure 4A.

[0142] The resin constituting the first frame portion 141, preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is preferably soft to a certain extent so that the heater element 100 is not easily damaged. Accordingly, in one embodiment, the resin constituting the first frame portion 141, preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is preferably 150 HRR or less, more preferably 140 HRR or less, and even more preferably 130 HRR or less, as measured in accordance with ASTM D785-2008 R15. In another embodiment, the resin constituting the first frame portion 141, preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is preferably 120 HRM or less, more preferably 110 HRM or less, and even more preferably 100 HRM or less, as measured in accordance with ASTM D785-2008 R15. The resin constituting the first frame portion 141, and preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, can satisfy the conditions regarding the upper limit of either one of the Rockwell hardness HRR and HRM described above, and it is desirable that both conditions be satisfied.

[0143] On the other hand, from the viewpoint of improving the holding performance for the heater element 100, it is desirable that the resin constituting the first frame portion 141, preferably the first frame portion 141 plus the second frame portion 142 and the third frame portion 143, has a certain degree of hardness. Therefore, in one embodiment, the resin constituting the first frame portion 141, preferably the first frame portion 141 plus the second frame portion 142 and the third frame portion 143, preferably has a Rockwell hardness lower limit of 70 HRR or higher, more preferably 80 HRR or higher, and even more preferably 85 HRR or higher, as measured in accordance with ASTM D785-2008 R15. In another embodiment, the resin constituting the first frame portion 141, preferably the first frame portion 141 plus the second frame portion 142 and the third frame portion 143, preferably has a Rockwell hardness lower limit of 70 HRM or higher, more preferably 80 HRM or higher, and even more preferably 85 HRM or higher, as measured in accordance with ASTM D785-2008 R15. The resin constituting the first frame portion 141, and preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, can satisfy the conditions for the lower limit of either one of the Rockwell hardness HRR and HRM described above, and it is desirable that both conditions be satisfied.

[0144] Accordingly, in one embodiment, the resin constituting the first frame portion 141, preferably the first frame portion 141 in addition to the second frame portion 142 and the third frame portion 143, has a Rockwell hardness range measured in accordance with ASTM D785-2008 R15, for example, 70 HRR to 150 HRR. In another embodiment, the resin constituting the first frame portion 141, preferably the first frame portion 141 in addition to the second frame portion 142 and the third frame portion 143, has a Rockwell hardness range measured in accordance with ASTM D785-2008 R15, for example, 70 HRM to 120 HRM.

[0145] There are no particular restrictions on the type of resin that constitutes the first frame portion 141, the second frame portion 142, and the third frame portion 143. However, from the viewpoint of heat resistance and corrosion resistance, it is preferable that the first frame portion 141, and preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, contain one or both of polyetheretherketone (PEEK) and polybutylene terephthalate (PBT). It is more preferable that the total content of polyetheretherketone (PEEK) and polybutylene terephthalate (PBT) be 80% by mass or more, even more preferable that it be 90% by mass or more, and it may even be 100% by mass.

[0146] The resin constituting the first frame portion 141, and preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is preferably heat-resistant. Therefore, the first frame portion 141, and preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is preferably 145°C or higher, more preferably 160°C or higher, and even more preferably 180°C or higher, as measured in accordance with JIS K7191-1:2015. There is no particular upper limit set for the load deflection temperature, but from the viewpoint of availability, it is usually 300°C or lower, and typically 250°C or lower. Therefore, the resin constituting the first frame portion 141, and preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, has a load deflection temperature range of, for example, 145°C or more and 300°C or less.

[0147] The resin constituting the first frame portion 141, preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is desirable to have a high melting point so as not to melt when heated. Therefore, the first frame portion 141, preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is preferably at a lower limit of 250°C or higher, more preferably at 280°C or higher, and even more preferably at 300°C or higher. There is no particular upper limit set for the melting point, but from the viewpoint of availability, it is usually 400°C or lower, and typically 350°C or lower. Therefore, the resin constituting the first frame portion 141, preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, has a melting point range of, for example, 250°C or more and 400°C or less.

[0148] In this specification, the melting point of a resin refers to the lowest temperature at which an endothermic peak due to melting is observed when measured using TG-DTA (thermogravimetry - differential thermal analysis).

[0149] The resin constituting the first frame portion 141, preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is desirable to have a low thermal conductivity in order to reduce heat loss. Therefore, the first frame portion 141, preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is preferably 0.5 W / m / K or less, more preferably 0.3 W / m / K or less, and even more preferably 0.2 W / m / K or less, as measured at 25°C in accordance with JIS R1611:2010. There is no particular lower limit set for the thermal conductivity, but from the viewpoint of availability, it is usually 0.1 W / m / K or more, and typically 0.15 W / m / K or more. Therefore, the resin constituting the first frame portion 141, preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, has a thermal conductivity in the range of, for example, 0.1 W / m / K or more and 0.5 W / m / K or less.

[0150] The resin constituting the first frame portion 141, and preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, is preferably insulating in order to suppress short circuits. Therefore, the first frame portion 141, and preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, should have a lower limit of volume resistivity at 25°C measured in accordance with the bridge method of JIS C2139:2008 of 1.0 × 10⁻⁶. 16 It is preferable that the value be Ω·cm or greater, and 2.0 × 10 16 It is preferable that it be Ω·cm or more, and 2.5 × 10 16 A value of Ω·cm or greater is more preferable. While there is no specific upper limit set for volume resistivity, from the standpoint of availability, it is usually 1.0 × 10⁻⁶. 17 It is less than Ω·cm, and is typically 0.5 × 10⁻⁶. 17 It is Ω·cm or less. Therefore, the resin constituting the first frame portion 141, and preferably the second frame portion 142 and the third frame portion 143 in addition to the first frame portion 141, has a volume resistivity in the range of, for example, 1.0 × 10⁻⁶. 16 Ω cm or more 1.0×10 17 It is less than or equal to Ω·cm.

[0151] From the viewpoint of ensuring deformation allowance to exert a cushioning effect, the thickness of the cushioning material 150 in the compression direction, which is compressed by being sandwiched between the inner circumferential surface 141i of the first frame portion 141 and the outer circumferential surface 103e of the outer circumferential wall 103 of the honeycomb structure portion, is preferably at a lower limit of 0.5 mm or more, more preferably at a lower limit of 1.0 mm or more, and even more preferably at a lower limit of 2.0 mm or more. From the viewpoint of making it compact and reducing the space required for mounting, the thickness of the cushioning material 150 in the compression direction, which is compressed by being sandwiched between the inner circumferential surface 141i of the first frame portion 141 and the outer circumferential surface 103e of the outer circumferential wall 103 of the honeycomb structure portion, is preferably at an upper limit of 7.0 mm or less, more preferably at a lower limit of 5.0 mm or less, and even more preferably at a lower limit of 4.0 mm or more. Therefore, the thickness range in the compression direction of the cushioning material 150, which is compressed by being sandwiched between the inner circumferential surface 141i of the first frame portion 141 and the outer circumferential surface 103e of the outer circumferential wall 103 of the honeycomb structure portion and subjected to pressure, can be, for example, 0.5 mm or more and 7.0 mm or less.

[0152] From the viewpoint of ensuring deformation allowance to exert a cushioning effect, the thickness of the cushioning material 129 in the compression direction, when compressed by the pressure of the second frame portion 142 (third frame portion 143), is preferably 0.5 mm or more at the lower limit, more preferably 1.0 mm or more, and even more preferably 2.0 mm or more. From the viewpoint of making it compact and reducing the space required for installation, the thickness of the cushioning material 129 in the compression direction, when compressed by the pressure of the second frame portion 142 (third frame portion 143), is preferably 7.0 mm or less at the upper limit, more preferably 5.0 mm or less, and even more preferably 4.0 mm or less. Therefore, the range of the thickness of the cushioning material 129 in the compression direction, when compressed by the pressure of the second frame portion 142 (third frame portion 143), can be, for example, 0.5 mm or more and 7.0 mm or less.

[0153] From the viewpoint of ensuring holding force against the honeycomb heater element, the Young's modulus of the cushioning material 150 and cushioning material 129 is preferably 0.05 MPa or higher at the lower limit, more preferably 0.06 MPa or higher, and even more preferably 0.07 MPa or higher. From the viewpoint of ensuring deformation allowance to exert a cushioning effect, the Young's modulus of the cushioning material 150 and cushioning material 129 is preferably 0.3 MPa or lower at the upper limit, more preferably 0.25 MPa or lower, and even more preferably 0.2 MPa or lower. Therefore, the range of the Young's modulus of the cushioning material 150 and cushioning material 129 can be, for example, 0.05 MPa or higher and 0.3 MPa or lower.

[0154] The Young's modulus of cushioning material 150 and cushioning material 129 is determined from the relationship between surface pressure and thickness change when a sheet-shaped cushioning material is compressed by gradually applying surface pressure.

[0155] There are no particular restrictions on the type of material that constitutes the cushioning material 150 and cushioning material 129, but from the viewpoint of ensuring sufficient deformation allowance, it is preferable that it be made of rubber, and more preferably of rubber sponge. The rubber and rubber sponge can contain various types of rubber such as natural rubber, styrene-butadiene rubber, butadiene rubber, chloroprene rubber, ethylene-propylene rubber, butyl rubber, fluororubber, acrylonitrile-butadiene rubber, silicone rubber, isoprene rubber, urethane rubber, chlorosulfonated polyethylene, hydrogenated nitrile rubber, epichlorohydrin rubber, acrylic rubber, ethylene acrylic rubber, norbornene rubber, and these may be contained individually or in a mixture of two or more types. Among these, it is more preferable that the cushioning material 150 be made of silicone rubber sponge with silicone rubber as the main component (preferably 60% by mass or more, more preferably 80% by mass or more).

[0156] From the viewpoint of ensuring cushioning performance, the thickness of the cushioning material 145 compressed by being sandwiched between a pair of split members 140a and 140b is preferably 0.1 mm or more in the compression direction, more preferably 0.2 mm or more, and even more preferably 0.5 mm or more. From the viewpoint of ensuring rigidity, the upper limit of the thickness of the compressed cushioning material 145 in the compression direction is preferably 3 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less. Therefore, the range of the thickness of the compressed cushioning material 145 in the compression direction can be, for example, 0.1 mm or more and 3 mm or less.

[0157] From the viewpoint of ensuring structural rigidity, the Young's modulus of the cushioning material 145 is preferably 0.05 MPa or higher at the lower limit, more preferably 0.08 MPa or higher, and even more preferably 0.1 MPa or higher. From the viewpoint of ensuring cushioning function, the Young's modulus of the cushioning material 145 is preferably 0.3 MPa or lower at the upper limit, more preferably 0.2 MPa or lower, and even more preferably 0.15 MPa or lower. Therefore, the range of the Young's modulus of the cushioning material 145 can be, for example, 0.05 MPa or higher and 0.3 MPa or lower.

[0158] The method for measuring the Young's modulus of cushioning material 145 is as described in the explanation of cushioning material 150.

[0159] The materials constituting the cushioning material 145 are as described in the description of the cushioning material 150, including preferred embodiments.

[0160] (3. Method for manufacturing a heater element) Next, a method for manufacturing a heater element according to the present invention will be described exemplified. The manufacturing method for the honeycomb structure that constitutes the heater element includes a molding step and a firing step. In the molding process, a clay mold containing ceramic raw materials including BaCO3 powder, TiO2 powder, and rare earth nitrate or hydroxide powder is molded to produce a honeycomb molded body with a relative density of 60% or more. Ceramic raw materials can be obtained by dry-mixing each powder to achieve the desired composition. The clay can be obtained by adding a dispersion medium, binder, plasticizer, and dispersant to ceramic raw materials and kneading them together. The clay may also contain additives such as sifters, metal oxides, property improvers, and conductive powders as needed. The amount of components other than ceramic raw materials is not particularly limited, as long as it is such that the relative density of the honeycomb molded body is 60% or more.

[0161] Here, in this specification, "relative density of the honeycomb molded body" means the ratio of the density of the honeycomb molded body to the true density of the entire ceramic raw material. Specifically, it can be calculated by the following formula. Relative density (%) of honeycomb molded material = Density (g / cm³) of honeycomb molded material 3 ) / True density of the entire ceramic raw material (g / cm³) 3 ) × 100 The density of a honeycomb molded body can be measured by the Archimedes method using pure water as the medium. The true density of the entire ceramic material is calculated by adding the mass of each material (g) and then adding the actual volume of each material (cm³). 3It can be found by dividing by ).

[0162] Examples of dispersion media include water, or a mixed solvent of water and an organic solvent such as alcohol, but water is particularly suitable.

[0163] Examples of binders include organic binders such as methylcellulose, hydroxypropoxylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. In particular, the combined use of methylcellulose and hydroxypropoxylcellulose is preferred. A single binder may be used, or two or more may be used in combination, but it is preferable that the binder does not contain alkali metal elements.

[0164] Examples of plasticizers include polyoxyalkylene alkyl ethers, polycarboxylic acid polymers, and alkyl phosphate esters.

[0165] Dispersants that can be used include surfactants such as polyoxyalkylene alkyl ethers, ethylene glycol, dextrin, fatty acid soaps, and polyalcohols. Dispersants may be used individually or in combination of two or more types.

[0166] Honeycomb molded bodies can be manufactured by extruding clay. During extrusion molding, a die with the desired overall shape, cell shape, partition wall thickness, cell density, etc., can be used.

[0167] The lower limit of the relative density of the honeycomb molded body obtained by extrusion molding is preferably 60% or more, and more preferably 65% ​​or more. By controlling the relative density of the honeycomb molded body within this range, it is possible to densify the honeycomb molded body and reduce its electrical resistance at room temperature. The upper limit of the relative density of the honeycomb molded body is not particularly limited, but is generally 80% or less, and preferably 75% or less.

[0168] The honeycomb molded body can be dried before the firing process. The drying method is not particularly limited, but conventional known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying can be used. Among these, a drying method combining hot air drying with microwave drying or dielectric drying is preferred because it can dry the entire molded body quickly and uniformly.

[0169] The firing process includes maintaining the temperature at 1150-1250°C, then increasing the temperature to a maximum of 1360-1430°C at a heating rate of 20-600°C / hour, and maintaining the temperature for 0.5-10 hours. By holding the honeycomb molded body at a maximum temperature of 1360-1430°C for 0.5-10 hours, a honeycomb structure mainly composed of BaTiO3-based crystalline grains in which some of the Ba is replaced by rare earth elements can be obtained. Furthermore, by maintaining the temperature at 1150-1250°C, the Ba2TiO4 crystal particles generated during the firing process are more easily removed, thereby densifying the honeycomb structure. Furthermore, by setting the heating rate from 1150-1250°C to the maximum temperature of 1360-1430°C to 20-600°C / hour, 1.0-10.0 mass% of Ba6Ti 17 O 40 Crystal grains can be generated in the honeycomb structure.

[0170] The holding time at 1150-1250°C is not particularly limited, but is preferably 0.5-10 hours. This holding time makes it easier to stably remove the Ba2TiO4 crystal grains generated during the firing process.

[0171] The firing process preferably includes holding the temperature at 900-950°C for 0.5-5 hours during the heating phase. Holding the temperature at 900-950°C for 0.5-5 hours allows BaCO3 to decompose efficiently, making it easier to obtain a honeycomb structure with a predetermined composition.

[0172] Furthermore, a degreasing process may be performed before the firing process to remove the binder. The atmosphere during the degreasing process is preferably atmospheric air to completely decompose the organic components. Furthermore, the atmosphere during the firing process is preferably an atmospheric environment, from the viewpoint of controlling electrical properties and reducing manufacturing costs. The furnace used in the firing and degreasing processes is not particularly limited, but electric furnaces, gas furnaces, etc., can be used.

[0173] A heater element can be manufactured by joining a pair of electrode layers (first electrode layer 102a and second electrode layer 102b) to the honeycomb structure obtained in this way. The first electrode layer 102a and the second electrode layer 102b can be formed on the first end face 101a and the second end face 101b of the honeycomb structure by metal deposition methods such as sputtering, vapor deposition, electrolytic deposition, and chemical deposition. Alternatively, the first electrode layer 102a and the second electrode layer 102b can be formed by applying electrode paste to the first end face 101a and the second end face 101b of the honeycomb structure and then baking it. Furthermore, they can also be formed by thermal spraying. The first electrode layer 102a and the second electrode layer 102b may be composed of a single layer, but they can also be composed of multiple electrode layers with different compositions. When forming the first electrode layer 102a and the second electrode layer 102b on the end face using the above method, the cells can be prevented from being blocked by setting the thickness of the electrode layer so as not to be excessively large.

[0174] The methods for forming the first electrode layer 102a and the second electrode layer 102b are not limited to those mentioned above, but include baking an electrode paste, dry plating such as sputtering and vapor deposition, wet plating such as electrolysis and chemical deposition, and joining of metal or alloy plates. Each method has a suitable thickness range. For baking an electrode paste, it can be about 5 to 30 μm; for dry plating such as sputtering and vapor deposition, it can be about 100 to 1000 nm; for thermal spraying, it can be about 10 to 100 μm; and for wet plating such as electrolysis and chemical deposition, it can be about 5 to 30 μm. In addition, when joining metal or alloy plates, the thickness of the electrode layer can be about 5 to 100 μm.

[0175] Next, the first terminal 109a is connected to the outer surface of the first electrode layer 102a, and the second terminal 109b is connected to the outer surface of the second electrode layer 102b. As mentioned above, methods for connecting the two include welding, brazing, or mechanical contact. Alternatively, the first terminal 109a (second terminal 109b) may be connected by baking it at the same time as baking the electrode paste for forming the first electrode layer 102a (second electrode layer 102b).

[0176] Next, the energizing components 105a and 105b are connected to the first terminal 109a and the second terminal 109b, respectively, as needed. As mentioned above, methods for connecting the two include welding, brazing, or mechanical contact.

[0177] Next, a first moisture-absorbing material-containing layer 107a is formed to cover a portion of the outer surface of the first electrode layer 102a, and a second moisture-absorbing material-containing layer 107b is formed to cover a portion of the outer surface of the second electrode layer 102b. In a preferred embodiment, a third moisture-absorbing material-containing layer 111a is formed to cover a portion of the outer surface of the first terminal 109a, and a fourth moisture-absorbing material-containing layer 111b is formed to cover a portion of the outer surface of the second terminal 109b. In a more preferred embodiment, a fifth moisture-absorbing material-containing layer 113 is formed to cover a portion or all of the surface of the partition wall 106 that forms the flow path inside the cell 104.

[0178] The first moisture-absorbing layer 107a, the second moisture-absorbing layer 107b, the third moisture-absorbing layer 111a, the fourth moisture-absorbing layer 111b, and the fifth moisture-absorbing layer 113 may be formed individually or simultaneously. These moisture-absorbing layers can be formed simultaneously, for example, by the following process: The heater element before the moisture-absorbing layers are formed is immersed for a predetermined time in a slurry containing a moisture-absorbing material, functional materials other than the moisture-absorbing material as needed, a binder, and a dispersion medium, and excess slurry from the outer surface of the honeycomb structure is removed by blowing and wiping. After that, these moisture-absorbing layers can be formed by drying the slurry. Drying can be carried out, for example, while heating the heater element to a temperature of about 120 to 600°C. The series of steps of immersion, slurry removal, and drying may be performed only once, but by repeating them multiple times, a moisture-absorbing layer of the desired thickness can be provided on the surface of an electrode layer or the like.

[0179] While organic binders may be used, it is preferable to use inorganic binders because they may emit smoke due to heat, and there is a concern that the components in the smoke may flow into the vehicle's interior, worsening the interior environment. The preferred types of inorganic binders are as described above.

[0180] The dispersion medium may be water, an organic solvent (e.g., toluene, xylene, ethanol, n-butanol, ethyl acetate, butyl acetate, terpineol, dihydroterpineol, texanol, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether), or a mixture thereof.

[0181] (4. Air conditioning system) According to one embodiment of the present invention, an air conditioning system is provided that includes the heater element described above. This air conditioning system can be used to improve the indoor space of various vehicles such as automobiles, as well as buildings such as houses, offices, factories, store warehouses, and freezers, and vehicles such as ships and airplanes.

[0182] (4-1. First Air Conditioning System 1000) Figure 6 is a schematic diagram showing the configuration of the first air conditioning system 1000 according to one embodiment of the present invention. The First Air Conditioning System 1000 is, At least one heater element 100, A power source 200 such as a battery for applying voltage to the heater element 100, An inlet pipe 400 connects the interior of the vehicle, such as the passenger compartment, to the inlet end face of the heater element 100, An outflow pipe 500 having a first path 500a that connects the outlet end face of the heater element 100 to the interior, A ventilator 600 for drawing air from inside the room into the inlet end face of the heater element 100 via an inlet pipe 400, It is equipped with.

[0183] In the air conditioning system shown in Figure 6, the heater element 100 is arranged such that its inlet end face is the first end face 101a and its outlet end face is the second end face 101b. However, it is also possible to arrange the heater element 100 so that its inlet end face is the second end face 101b and its outlet end face is the first end face 101a. There may be only one heater element 100, or multiple heater elements may be arranged in series or parallel.

[0184] The outlet pipe 500 may have a second route 500b in addition to the first route 500a, which connects the outlet end face of the heater element 100 to the outside of the vehicle or other outdoor area. The outlet pipe 500 may also have a switching valve 300 that can switch the airflow through the outlet pipe 500 between the first route 500a and the second route 500b.

[0185] The First Air Conditioning System 1000 is, In the first mode, the applied voltage from the power supply 200 is turned off, the switching valve 300 is switched so that the air flowing through the outflow pipe 500 passes through the first path 500a, and the ventilator 600 is turned on. In the second mode, the voltage applied from the power supply 200 is turned on, the switching valve 300 is switched so that the air flowing through the outflow pipe 500 passes through the second path 500b, and the ventilator 600 is turned on. It can have the following operating modes.

[0186] The first air conditioning system 1000 may include a control unit 900 capable of switching between a first mode and a second mode. The control unit 900 may be configured, for example, to alternate between the first mode and the second mode. By repeating the switching between the first mode and the second mode in a fixed cycle, it becomes possible to stably discharge components to be removed, such as water vapor from the interior, to the outside of the vehicle.

[0187] In the first mode, the components to be removed from the air are removed. Specifically, air from the room flows in through the inlet pipe 400 and into the heater element 100 from the inlet end face, passes through the heater element 100, and then flows out from the outlet end face of the heater element 100. The components to be removed from the air from the room are removed by being captured by a functional material such as a desiccant while passing through the heater element 100. The air from which the components to be removed have been removed, which flows out from the outlet end face of the heater element 100, is returned to the room through the first path 500a of the outlet pipe 500. This air may be supplied to other air conditioning systems (e.g., vehicle HVAC).

[0188] In the second mode, functional materials such as moisture absorbers are regenerated. Specifically, air from the room flows in through the inlet pipe 400 and into the inlet end face of the heater element 100, passes through the heater element 100, and then flows out from the outlet end face of the heater element 100. The heater element 100 generates heat when electricity is applied, which heats the functional material supported on the heater element 100, causing the components to be removed, such as those captured by the functional material, to detach from the functional material or react with it.

[0189] To promote the release of components to be removed that have been captured by the functional material, it is preferable to heat the functional material to a temperature above the release temperature, depending on the type of functional material. When a hygroscopic material is used as the functional material, it is preferable to heat at least a part of the hygroscopic material, preferably all of it, to 70-150°C, more preferably to 80-140°C, and even more preferably to 90-130°C. Furthermore, it is desirable to perform the second mode for a period of time until the functional material has been sufficiently regenerated. Depending on the type of functional material, for example, when a hygroscopic material is used as the functional material, in the second mode, it is preferable to heat the functional material in the above temperature range for 1-10 minutes, more preferably to 2-8 minutes, and even more preferably to 3-6 minutes.

[0190] In the second mode, indoor air flows out from the outlet end face of the heater element 100, carrying with it the components to be removed that have detached from the functional material while passing through the heater element 100. The air containing the components to be removed that flows out from the outlet end face of the heater element 100 is discharged to the outside through the second path 500b of the outlet pipe 500.

[0191] Switching the applied voltage to the heater element 100 on and off can be done, for example, by electrically connecting the power supply 200 and a pair of terminals 109a and 109b of the heater element 100 with a wire 810 and operating a power switch 910 located along the wire. The operation of the power switch 910 can be performed by the control unit 900.

[0192] The ventilation fan 600 can be switched on and off, for example, by electrically connecting the control unit 900 and the ventilation fan 600 with an electric wire 820 or wirelessly, and by operating a switch (not shown) on the ventilation fan 600 using the control unit 900. The ventilation fan 600 can also be configured so that the amount of airflow can be changed by the control unit 900.

[0193] Switching of the switching valve 300 can be done, for example, by electrically connecting the control unit 900 and the switching valve 300 with an electric wire 830 or wirelessly, and by operating the switch (not shown) of the switching valve 300 with the control unit 900.

[0194] The switching valve 300 is not particularly limited as long as it is electrically driven and has the function of switching the flow path, but examples include solenoid valves and motorized valves. In one embodiment, the switching valve 300 includes an opening / closing door 312 supported on a rotating shaft 310 and an actuator 314 such as a motor that rotates the rotating shaft 310. The actuator 314 is configured to be controllable by a control unit 900.

[0195] From the viewpoint of ensuring the above functions stably, it is desirable that the heater element 100 of the first air conditioning system 1000 be positioned close to the room. Therefore, from the viewpoint of preventing electric shock, it is preferable that the drive voltage be 60V or less. The honeycomb structure used in the heater element 100 has low electrical resistance at room temperature, so it is possible to heat the honeycomb structure with this low drive voltage. The lower limit of the drive voltage is not particularly limited, but it is preferable that it be 10V or more. If the drive voltage is less than 10V, the current when heating the honeycomb structure will be large, so it will be necessary to make the electric wire 810 thicker. Therefore, the drive voltage of the first air conditioning system 1000 can be, for example, 10V or more and 60V or less.

[0196] In the embodiment shown in Figure 6, the ventilator 600 is installed upstream of the heater element 100. More specifically, the ventilator 600 is installed in the middle of the inlet pipe 400 that connects the heater element 100 to the room, and the air that passes through the ventilator 600 flows into the heater element 100 in a way that it is pushed in. Alternatively, the ventilator 600 may be installed downstream of the heater element 100. In this case, the ventilator 600 can be installed, for example, in the middle of the outlet pipe 500, and the air that passes through the inlet pipe 400 flows into the heater element 100 in a way that it is drawn in. [Examples]

[0197] [1. Specifications of the honeycomb structure] We prepared a honeycomb structure with the following specifications. • Cross-sectional and end face shapes of the honeycomb structure perpendicular to the direction of the flow path: square (radius of curvature 6 mm or more) • Cell opening shape perpendicular to the direction of the flow path: Square with rounded corners • Partition thickness: 0.100 mm • Thickness of the outer wall: 0.3 mm • Cell density: 80 cells / cm² 2 Cell pitch: 1.11mm • Cell aperture ratio: 0.797 • Size of the cross-section perpendicular to the direction in which the flow channels of the honeycomb structure extend: 90mm x 90mm • Length of the flow channel in the honeycomb structure in the direction of extension: 12 mm • Volume resistivity of the materials constituting the outer walls and partitions at 25°C: 15 Ω·cm • Curie point of materials constituting the outer walls and partitions: 120°C • Materials constituting the outer walls and partitions: Barium titanate • Density of the materials constituting the outer walls and partitions: 5750 kg / m³ 3 • Specific heat of the materials constituting the outer walls and partitions: 550 J / kg / K

[0198] [2. Characteristics of the moisture absorbent material used] Commercially available amorphous aluminum silicate was prepared as a desiccant. 5 g of amorphous aluminum silicate, dried at 180°C for more than 2 hours, was placed in a constant temperature and humidity chamber at room temperature (25°C) and relative humidity of 50% for 1 hour. The amount of water that could be adsorbed per gram of dry weight was determined from the increase in mass of the amorphous aluminum silicate removed from the constant temperature and humidity chamber. The results are shown in Table 1.

[0199] The mass change of 5 g of amorphous aluminum silicate, dried at 180°C for more than 2 hours, was investigated when placed in a constant temperature and humidity chamber at 50% relative humidity and left for 1 hour at various temperatures. This allowed us to determine the temperature range in which the amount of water adsorbed per 1 g of dry mass was 5 g / g or more, and the upper limit of this range was defined as the water adsorption temperature. The results are shown in Table 1. Note that the amount of water adsorbed increases as the temperature decreases.

[0200] Five g of amorphous aluminum silicate, dried at 180°C for more than two hours, was left in a constant temperature and humidity chamber at room temperature (25°C) and 50% relative humidity for one hour to allow moisture to adsorb. The change in mass of the amorphous aluminum silicate after moisture adsorption was investigated when it was placed in a constant temperature and humidity chamber at 50% relative humidity and left at various temperatures for 0.1 hours. The lowest temperature at which the mass reduction rate relative to the amorphous aluminum silicate after moisture adsorption was 30% was defined as the moisture release temperature. The results are shown in Table 1.

[0201] [3. Manufacturing of Heater Elements] The heater elements according to the following examples and comparative examples were manufactured in quantities necessary for various analyses and tests. <Example 1> A paste made by mixing aluminum powder with a binder resin was applied to both end faces (first end face 101a and second end face 101b) of the above-mentioned honeycomb structure and baked to form a pair of electrode layers (first electrode layer 102a and second electrode layer 102b) (see Table 1 for volume resistivity at 25°C).

[0202] Table 1 shows the results of calculating the percentage (coverage rate) of the area of ​​the first end face 101a (second end face 101b) covered by the first electrode layer 102a (second electrode layer 102b) out of the area of ​​the cell 104 excluding the opening (partition wall portion and outer peripheral wall portion) on the first end face 101a (second end face 101b), based on the areas of both. In addition, the average thickness of the first electrode layer 102a (second electrode layer 102b) was measured using the measurement method described above. The results are shown in Table 1.

[0203] Next, the first terminal 109a and the second terminal 109b, which are rectangular plate-shaped pieces made of pure aluminum (A1050) (see Table 1 for volume resistivity at 25°C) and have the planar dimensions and thickness shown in Table 1, were soldered to the outer surfaces of the first electrode layer 102a and the second electrode layer 102b, specifically to the outer periphery of the first end face 101a and the second end face 101b, respectively. Then, the wires, which are the conductive components 105a and 105b, were soldered to the outer surfaces of the first terminal 109a and the second terminal 109b, respectively.

[0204] The ratio (coverage rate) of the area of ​​the first terminal 109a (second terminal 109b) covering the first end face 101a (second end face 101b) to the area of ​​the first end face 101a (second end face 101b) was calculated based on the areas of both. The results are shown in Table 1.

[0205] Next, amorphous aluminum silicate powder, silica powder, and solvent (water) were mixed in a mass ratio of amorphous aluminum silicate:silica:solvent = 95:5:100 and stirred to prepare a hygroscopic slurry. The obtained hygroscopic slurry was applied to the outer surfaces of the first electrode layer 102a and the second electrode layer 102b by brush application, and then dried in a dryer at 190°C for 2 hours to form the first hygroscopic layer 107a and the second hygroscopic layer 107b, thereby preparing a heater element.

[0206] The ratio (coverage rate) of the area covered by the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b) to the area of ​​the outer surface of the first electrode layer 102a (second electrode layer 102b) where the first terminal 109a (second terminal 109b) is not connected was calculated based on the areas of both layers. The results are shown in Table 1. In addition, the average thickness of the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b) was measured using the measurement method described above. The results are shown in Table 1.

[0207] Following the procedure described above, electrical resistance measurements were performed at 12 locations each in the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b. The range of electrical resistance (minimum to maximum value) at this time is shown in Table 1.

[0208] <Example 2> In the same manner as in Example 1, a pair of electrode layers (first electrode layer 102a and second electrode layer 102b) were joined to both end faces of the honeycomb structure portion.

[0209] Next, in the same manner as in Example 1, the first terminal 109a and the second terminal 109b were respectively connected to the outer surfaces of the first electrode layer 102a and the second electrode layer 102b. Next, in the same manner as in Example 1, electric wires which are the energizing components 105a and 105b were respectively connected to the outer surfaces of the first terminal 109a and the second terminal 109b.

[0210] Next, the same moisture absorbent slurry as in Example 1 was applied to the outer surfaces of the first electrode layer 102a and the second electrode layer 102b, and the outer surfaces of the first terminal 109a and the second terminal 109b by a brush coating method, and then dried at 190 ° C for 2 hours in a dryer, thereby forming the first moisture absorbent containing layer 107a and the second moisture absorbent containing layer 107b, and the third moisture absorbent containing layer 111a and the fourth moisture absorbent containing layer 111b, and a heater element was manufactured.

[0211] Based on the areas of both, the ratio (coverage rate) of the area of the first moisture absorbent containing layer 107a (second moisture absorbent containing layer 107b) covering the outer surface of the first electrode layer 102a (second electrode layer 102b) to the area of the portion of the outer surface of the first electrode layer 102a (second electrode layer 102b) where the first terminal 109a (second terminal 109b) is not connected was calculated. Based on the areas of both, the ratio (coverage rate) of the area of the third moisture absorbent containing layer 111a (fourth moisture absorbent containing layer 111b) covering the outer surface of the first terminal 109a (second terminal 109b) to the area of the portion of the outer surface of the first terminal 109a (second terminal 109b) where the energizing component 105a is not connected was calculated. Also, the average thickness of the first moisture absorbent containing layer 107a (second moisture absorbent containing layer 107b) and the average thickness of the third moisture absorbent containing layer 111a (fourth moisture absorbent containing layer 111b) were measured by the above-described measurement procedure. The results are shown in Table 1.

[0212] In accordance with the above-described procedure, electrical resistance measurements were performed at 12 locations each on the first moisture absorbent-containing layer 107a and the second moisture absorbent-containing layer 107b. The range of electrical resistance (minimum value to maximum value) at this time is shown in Table 1. In accordance with the above-described procedure, the electrical resistance at 25°C between any two points separated by a distance of 3 mm on the outer surfaces of the third moisture absorbent-containing layer 111a and the fourth moisture absorbent-containing layer 111b was measured at 5 locations each. The range of electrical resistance (minimum value to maximum value) at this time is shown in Table 1.

[0213] <Example 3> In the same manner as in Example 1, a pair of electrode layers (first electrode layer 102a and second electrode layer 102b) were joined to both end faces of the honeycomb structure portion.

[0214] Next, in the same manner as in Example 1, the first terminal 109a and the second terminal 109b were connected to the outer surfaces of the first electrode layer 102a and the second electrode layer 102b, respectively. Next, in the same manner as in Example 1, electric wires, which are the energizing components 105a and 105b, were connected to the outer surfaces of the first terminal 109a and the second terminal 109b, respectively.

[0215] Next, the honeycomb structure portion with the electrode layer, terminals, and energizing components was immersed in the same bath of the moisture absorbent slurry as in Example 1 for 3 minutes. Thereafter, the honeycomb structure portion with the electrode layer, terminals, and energizing components was taken out of the bath, and the slurry on the outer peripheral surface of the honeycomb structure portion was removed by blowing and wiping. Next, by drying at 190°C for 2 hours in a dryer, the first moisture absorbent-containing layer 107a, the second moisture absorbent-containing layer 107b, the third moisture absorbent-containing layer 111a, the fourth moisture absorbent-containing layer 111b, and the fifth moisture absorbent-containing layer were formed, and a heater element was produced.

[0216] Based on the areas of both, the ratio (coverage rate) of the area of the first moisture absorbent-containing layer 107a (second moisture absorbent-containing layer 107b) covering the outer surface of the first electrode layer 102a (second electrode layer 102b) to the area of the portion of the outer surface of the first electrode layer 102a (second electrode layer 102b) where the first terminal 109a (second terminal 109b) is not connected was calculated. The ratio (coverage rate) of the area covered by the third moisture-absorbing material-containing layer 111a (fourth moisture-absorbing material-containing layer 111b) to the area of ​​the outer surface of the first terminal 109a (second terminal 109b) where the conductive component 105a is not connected was calculated based on the areas of both layers. The percentage of the surface area of ​​the partition wall 106 forming the flow path inside cell 104 that is covered by the fifth moisture-absorbing material-containing layer 113 (coverage rate) was calculated using the measurement procedure described above. In addition, the average thickness of the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b), the average thickness of the third moisture-absorbing material-containing layer 111a (fourth moisture-absorbing material-containing layer 111b), and the average thickness of the fifth moisture-absorbing material-containing layer 113 were measured using the measurement procedure described above. The results are shown in Table 1.

[0217] Following the procedure described above, electrical resistance measurements were performed at 12 locations each in the first moisture-absorbing layer 107a and the second moisture-absorbing layer 107b. The range of electrical resistance (minimum to maximum value) at this time is shown in Table 1. Following the procedure described above, the electrical resistance at 25°C was measured at five locations on the outer surfaces of the third moisture-absorbing layer 111a and the fourth moisture-absorbing layer 111b, at a distance of 3 mm between any two points. The range of electrical resistance (minimum to maximum value) at this time is shown in Table 1. Following the procedure described above, the electrical resistance of the fifth moisture-absorbing layer 113 was measured at five locations at 3 mm intervals. The range of electrical resistance (minimum to maximum value) at this time is shown in Table 1.

[0218] <Example 4> The heater element was manufactured in the same manner as in Example 1, except that the manufacturing conditions were changed as follows. The ratio of the area covered by the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b) to the area of ​​the outer surface of the first electrode layer 102a (second electrode layer 102b) where the first terminal 109a (second terminal 109b) is not connected (coverage rate) was changed to the values ​​shown in Table 1 by changing the application area of ​​the moisture-absorbing material slurry.

[0219] <Example 5> The heater element was manufactured in the same manner as in Example 2, except that the manufacturing conditions were changed as follows. The ratio of the area covered by the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b) to the area of ​​the outer surface of the first electrode layer 102a (second electrode layer 102b) where the first terminal 109a (second terminal 109b) is not connected (coverage rate) was changed to the values ​​shown in Table 1 by changing the application area of ​​the moisture-absorbing material slurry. The ratio of the area covered by the third moisture-absorbing material-containing layer 111a (fourth moisture-absorbing material-containing layer 111b) to the area of ​​the outer surface of the first terminal 109a (second terminal 109b) where the conductive component 105a is not connected (coverage rate) was changed to the values ​​shown in Table 1 by changing the application area of ​​the moisture-absorbing material slurry.

[0220] <Example 6> The heater element was manufactured in the same manner as in Example 3, except that the manufacturing conditions were changed as follows. The ratio of the area covered by the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b) to the area of ​​the outer surface of the first electrode layer 102a (second electrode layer 102b) where the first terminal 109a (second terminal 109b) is not connected (coverage rate) was changed to the values ​​shown in Table 1 by changing the application area of ​​the moisture-absorbing material slurry. The ratio of the area covered by the third moisture-absorbing material-containing layer 111a (fourth moisture-absorbing material-containing layer 111b) to the area of ​​the outer surface of the first terminal 109a (second terminal 109b) where the conductive component 105a is not connected (coverage rate) was changed to the values ​​shown in Table 1 by changing the application area of ​​the moisture-absorbing material slurry. The ratio of the surface area of ​​the partition wall 106 forming the flow path inside cell 104 that is covered by the fifth moisture-absorbing material-containing layer 113 (coverage rate) was changed to the values ​​shown in Table 1 by changing the method of immersing the honeycomb structure with the electrode layer, terminals, and conductive components in the bath of moisture-absorbing material slurry. Specifically, by performing the steps of immersing the honeycomb structure with the electrode layer, terminals, and conductive components in the bath of moisture-absorbing material slurry to a predetermined depth from the first end face 101a in the direction in which the cell extends, and immersing the honeycomb structure with the electrode layer, terminals, and conductive components in the bath of moisture-absorbing material slurry to a predetermined depth from the second end face 101b in the direction in which the cell extends, a region was created on the surface of the partition wall 106 forming the flow path inside cell 104 in which the moisture-absorbing material-containing layer is not formed. Furthermore, when immersing the honeycomb structure in the bath of moisture-absorbing slurry, the first end face 101a and the second end face 101b were masked to prevent the moisture-absorbing slurry from adhering to the first end face 101a and the second end face 101b.

[0221] <Example 7> The heater element was manufactured in the same manner as in Example 4, except that the manufacturing conditions were changed as follows. By adjusting the viscosity of the moisture-absorbing slurry, the average thickness of the first moisture-absorbing layer and the second moisture-absorbing layer was changed to the values ​​shown in Table 1.

[0222] <Example 8> The heater element was manufactured in the same manner as in Example 5, except that the manufacturing conditions were changed as follows. By changing the viscosity of the moisture-absorbing slurry, the average thickness of the first moisture-absorbing layer and the second moisture-absorbing layer was changed to the values ​​shown in Table 1. By changing the viscosity of the moisture-absorbing slurry, the average thickness of the third moisture-absorbing layer and the fourth moisture-absorbing layer was changed to the values ​​shown in Table 1.

[0223] <Example 9> The heater element was manufactured in the same manner as in Example 6, except that the manufacturing conditions were changed as follows. · By changing the viscosity of the moisture-absorbing material slurry, the average thicknesses of the first moisture-absorbing material-containing layer and the second moisture-absorbing material-containing layer were changed to the values described in Table 1. · By changing the viscosity of the moisture-absorbing material slurry, the average thicknesses of the third moisture-absorbing material-containing layer and the fourth moisture-absorbing material-containing layer were changed to the values described in Table 1. · By changing the viscosity of the moisture-absorbing material slurry, the average thickness of the fifth moisture-absorbing material-containing layer was changed to the value described in Table 1.

[0224] <Comparative Example 1> A heater element was produced in the same manner as in Example 1, except that the manufacturing conditions were changed as follows. · The first moisture-absorbing material-containing layer and the second moisture-absorbing material-containing layer were not formed.

[0225] <Comparative Example 2> A heater element was produced in the same manner as in Example 6, except that the manufacturing conditions were changed as follows. · After removing the slurry on both end faces and the outer peripheral surface of the honeycomb structure part taken out from the bath of the moisture-absorbing material slurry by blowing and wiping, the slurry was dried.

[0226] <Comparative Example 3> A pair of electrode layers (first electrode layer 102a and second electrode layer 102b) were joined to both end faces of the honeycomb structure part in the same manner as in Example 1.

[0227] Next, in the same manner as in Example 1, the first terminal 109a and the second terminal 109b were respectively connected to the outer surfaces of the first electrode layer 102a and the second electrode layer 102b. Next, in the same manner as in Example 1, the electric wires which are the energizing components 105a, 105b were respectively connected to the outer surfaces of the first terminal 109a and the second terminal 109b.

[0228] Next, a heater element was fabricated by introducing a polyamide powder resin with a particle size of approximately 100 μm into a thermal spray gun and coating the outer surface of the first electrode layer 102a and the outer surface of the second electrode layer 102b by thermal spraying using the heat of propane-oxygen combustion. In this heater element, the outer surface of the first electrode layer 102a is covered with a first resin-containing layer, and the outer surface of the second electrode layer 102b is covered with a second resin-containing layer.

[0229] The ratio of the area covered by the first resin-containing layer (second resin-containing layer) to the area of ​​the outer surface of the first electrode layer 102a (second electrode layer 102b) where the first terminal 109a (second terminal 109b) is not connected (coverage rate) was calculated based on the areas of both layers. This is shown in Table 1. In addition, the average thickness of the first resin-containing layer (second resin-containing layer) was measured using the same measurement method as the first moisture-absorbing material-containing layer 107a (second moisture-absorbing material-containing layer 107b). The results are shown in Table 1.

[0230] Electrical resistance measurements were performed at 12 locations on the first resin-containing layer and the second resin-containing layer, using the same method as for the first moisture-absorbing material-containing layer 107a and the second moisture-absorbing material-containing layer 107b. The range of electrical resistance (minimum to maximum value) is shown in Table 1.

[0231] <Comparative Example 4> A pair of electrode layers (first electrode layer 102a and second electrode layer 102b) were bonded to both end faces of the honeycomb structure using the same method as in Example 1.

[0232] Next, the first terminal 109a and the second terminal 109b were connected to the outer surfaces of the first electrode layer 102a and the second electrode layer 102b, respectively, using the same method as in Example 1. Then, the wires, which are the conductive components 105a and 105b, were connected to the outer surfaces of the first terminal 109a and the second terminal 109b, respectively, using the same method as in Example 1.

[0233] Next, a resin slurry was prepared by mixing polyamide powder resin with a particle size of approximately 100 μm and a solvent (ethyl alcohol) in a mass ratio of polyamide powder resin:solvent = 1:1 and stirring. The honeycomb structure with the electrode layer, terminals, and conductive components was immersed in this resin slurry bath for 10 seconds. After that, the honeycomb structure with the electrode layer, terminals, and conductive components was removed from the bath, and the slurry on the outer surface of the honeycomb structure was removed by blowing and wiping. Next, a heater element was prepared by drying in a dryer at 80°C for 0.5 hours and then heat-treating at 250°C. In this heater element, the outer surface of the first electrode layer 102a is covered with a first resin-containing layer, and the outer surface of the second electrode layer 102b is covered with a second resin-containing layer. In addition, the outer surface of the first terminal 109a is covered with a third resin-containing layer, and the outer surface of the second terminal 109b is covered with a fourth resin-containing layer. Furthermore, the fifth resin-containing layer covers the surface of the partition wall 106 that forms the flow path inside the cell 104.

[0234] The ratio (coverage rate) of the area covered by the first resin-containing layer (second resin-containing layer) to the area of ​​the outer surface of the first electrode layer 102a (second electrode layer 102b) where the first terminal 109a (second terminal 109b) is not connected was calculated based on the areas of both layers. The ratio of the area covered by the third resin-containing layer (fourth resin-containing layer) to the area of ​​the outer surface of the first terminal 109a (second terminal 109b) where the conductive component 105a is not connected (coverage rate) was calculated based on the areas of both. The percentage of the surface area of ​​the partition wall 106 forming the flow path inside cell 104 that is covered by the fifth resin-containing layer (coverage rate) was calculated using the same measurement procedure as for the fifth moisture-absorbing material-containing layer. Furthermore, the average thickness of the first resin-containing layer (second resin-containing layer), the average thickness of the third resin-containing layer (fourth resin-containing layer), and the average thickness of the fifth resin-containing layer were measured using the measurement procedure described above. The results are shown in Table 1.

[0235] Electrical resistance measurements were performed at 12 locations on the first resin-containing layer and the second resin-containing layer, using the same method as for the first moisture-absorbing material-containing layer 107a and the second moisture-absorbing material-containing layer 107b. The range of electrical resistance (minimum to maximum value) is shown in Table 1. The electrical resistance of the third resin-containing layer and the fourth resin-containing layer was measured at 12 locations, using the same method as for the third moisture-absorbing material-containing layer 111a and the fourth moisture-absorbing material-containing layer 111b. The range of electrical resistance (minimum to maximum value) is shown in Table 1. The electrical resistance of the fifth resin-containing layer was measured at 12 locations using the same method as that used for the fifth moisture-absorbing material-containing layer 113. The range of electrical resistance (minimum to maximum value) at this time is shown in Table 1.

[0236] Note that the polymer used in Comparative Example 3 and Comparative Example 4 a The moisture absorption properties of the mido resin were investigated. a 5g of imide resin was left in a constant temperature and humidity chamber at room temperature (25°C) and relative humidity of 50% for one hour. a When the amount of water that could be adsorbed per gram of dry mass was determined from the increased mass of the mido resin, the amount of water absorbed was not sufficient to meet the definition of a desiccant. The results are shown in Table 1.

[0237] [4. Evaluation of the heater element] The heater elements obtained by the above manufacturing method in the examples and comparative examples were evaluated for their moisture absorption characteristics, condensation generation, and short-circuit prevention effect. Only the necessary number of heater elements for the examples and comparative examples were prepared for evaluation.

[0238] <Moisture absorption properties> Using the measurement procedure described above, the total maximum water absorption capacity of the heater element, as well as the maximum water absorption capacity of the first and second regions of the heater element, were measured. The results are shown in Table 1.

[0239] <Condensation occurrence status> The heater element was cooled to -10°C. Then, air at 80°C and 90% relative humidity was flowed through each cell of the heater element at a flow rate of 2 m / sec for 5 minutes. During this process, the amount of droplets detected downstream of the heater element was measured using a droplet detection sheet from Nippon Paper Industries Co., Ltd., employing a method based on the coefficient of the color change point. Evaluation was performed according to the following criteria. The results are shown in Table 1. Not detected: Less than 3 discoloration points Trace amounts: 3 or more discoloration points and less than 10 Large quantity: 10 or more discoloration points

[0240] <Short-circuit prevention effect> The heater element was placed in an environment of 90°C and 90% relative humidity. The electrical resistance of the heater element was measured every 100 hours by applying a 12V voltage to a pair of electrode layers via a wire. The time elapsed until the electrical resistance increased by more than 10% from the initial value was investigated. Evaluation was performed according to the following criteria. The results are shown in Table 1. 〇: 800 hours or more △: 500hr~800hr ×: Less than 500 hours

[0241] [Table 1-1]

[0242] [Table 1-2]

[0243] [Table 1-3] [Explanation of Symbols]

[0244] 100: Heater element 101a: First end surface 101b: Second end surface 102a: First electrode layer 102b: Second electrode layer 103:Outer wall 103e: Outer surface 104: Cell 105a: Conductive components 105b: Conductive components 106: Bulkhead 107a: First moisture absorbing material containing layer 107b: Second moisture-absorbing material-containing layer 109a: First terminal 109b: Second terminal 111a: Third moisture absorbing material containing layer 111b: Fourth moisture absorbent containing layer 113:Fifth moisture absorbent layer 120: Frame 121: First Frame Section 121a: Holding part 121b: Flange section 122: Second Slot Section 122a: Holding part 122b: Flange section 124: Fasteners 125: Recess 126a: A portion that protrudes locally towards the inner circumference. 126b: A portion that protrudes locally towards the inner circumference. 127: Cushioning material 129: Cushioning material 140: Frame 140a: Components 140b: Components 141: First Frame Section 141i: Inner surface 142: Second Frame Section 143: Third Frame Section 144:Connection part 144a: Convex part 144b: recess 145: Cushioning material 150: Cushioning material 200: Power supply 300: Switching valve 310: Rotation axis 312: Opening / closing door 314: Actuator 400: Inflow piping 500: Outlet piping 500a: First route 500b: Second route 600: Ventilator 810:Electric wire 820:Electric wire 830:Electric wire 900: Control Unit 910: Power switch 1000: First Air Conditioning System

Claims

1. A honeycomb structure comprising an outer periphery wall and a partition wall disposed on the inner periphery side of the outer periphery wall, which divides and forms a plurality of cells that form a flow channel extending from a first end face to a second end face, and which contains a material having PTC properties, and which is capable of generating heat by electricity; A first electrode layer covering part or all of the surface of the partition wall forming the first end face; A second electrode layer covering part or all of the surface of the partition wall forming the second end face; A first moisture-absorbing material-containing layer covering a portion of the outer surface of the first electrode layer; and A second moisture-absorbing material-containing layer covering a portion of the outer surface of the second electrode layer; A heater element equipped with the following features.

2. The heater element according to claim 1, wherein the average thickness of at least one of the first moisture-absorbing material-containing layer and the second moisture-absorbing material-containing layer is 10 μm or more and 500 μm or less.

3. The heater element according to claim 1 or 2, wherein the maximum water absorption capacity (g) of the heater element per unit volume (1 liter) of the honeycomb structure is 20 to 400 g / liter.

4. The heater element according to claim 1 or 2, wherein the first moisture-absorbing material-containing layer and the second moisture-absorbing material-containing layer are insulating.

5. The heater element according to claim 1 or 2, wherein the first moisture-absorbing material-containing layer and the second moisture-absorbing material-containing layer contain an inorganic binder.

6. The heater element according to claim 1 or 2, wherein the first moisture-absorbing material-containing layer and the second moisture-absorbing material-containing layer contain, in addition to the moisture-absorbing material, a functional material having the function of adsorbing carbon dioxide and / or organic gas components.

7. If the first region is defined as the portion of the cell extending 0.5 cm from the outer surface to the second end face of the first moisture-absorbing material-containing layer, then the maximum water absorption per unit volume (1 liter) of the first region is 90 to 200 g / liter. If the second region is defined as the portion of the cell extending 0.5 cm from the outer surface of the second moisture-absorbing material-containing layer toward the first end face in the direction of cell extension, then the maximum water absorption per unit volume (1 liter) of the second region is 90 to 200 g / liter. The heater element according to claim 1 or 2.

8. The heater element according to claim 1 or 2, wherein the average thickness of the first electrode layer and the second electrode layer is 5 μm or more and 100 μm or less, respectively.

9. The first moisture-absorbing material-containing layer covers 80% or more of the area of ​​the outer surface of the first electrode layer where the first terminal is not connected. The second moisture-absorbing layer covers 80% or more of the area of ​​the outer surface of the second electrode layer where the second terminal is not connected. The heater element according to claim 1 or 2.

10. A first terminal connected to the portion of the outer surface of the first electrode layer that is not covered by the first moisture-absorbing material-containing layer; A second terminal connected to the portion of the outer surface of the second electrode layer that is not covered by the second moisture-absorbing material-containing layer; A third moisture-absorbing material-containing layer covering a portion of the outer surface of the first terminal; and A fourth moisture-absorbing material-containing layer covering a portion of the outer surface of the second terminal; A heater element according to claim 1 or 2, comprising:

11. The heater element according to claim 10, wherein the third moisture-absorbing layer and the fourth moisture-absorbing layer are insulating.

12. The heater element according to claim 10, wherein the third moisture-absorbing material-containing layer and the fourth moisture-absorbing material-containing layer contain an inorganic binder.

13. The heater element according to claim 10, wherein the third moisture-absorbing material-containing layer and the fourth moisture-absorbing material-containing layer contain, in addition to the moisture-absorbing material, a functional material having the function of adsorbing carbon dioxide and / or organic gas components.

14. The heater element according to claim 1 or 2, wherein the first electrode layer and the second electrode layer contain one or more selected from pure aluminum, aluminum alloy, and stainless steel.

15. The heater element according to claim 14, wherein the first electrode layer and the second electrode layer have a single layer of pure aluminum, a two-layer structure of an Al-Ni alloy layer and a pure silver layer, or a two-layer structure of an Al-Ni alloy layer and a pure aluminum layer.

16. The first terminal and the second terminal contain one or more selected from pure aluminum, aluminum alloy, and stainless steel. The first terminal is connected to the portion of the outer surface of the first electrode layer that is not covered by the first moisture-absorbing material-containing layer by welding, brazing, or mechanical contact. The second terminal is connected by welding, brazing, or mechanical contact to the portion of the outer surface of the second electrode layer that is not covered by the second moisture-absorbing material-containing layer. The heater element according to claim 10.

17. The heater element according to claim 1 or 2, further comprising a fifth moisture-absorbing material-containing layer that covers part or all of the surface of the partition wall forming the flow path inside the cell.

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