Film-shaped heater

Abstract

The present invention provides a film-shaped heater having a substantially uniform temperature therein. This film-shaped heater includes a heat-generating layer. When viewing a main surface of said heater from a direction perpendicular thereto, the heat-generating layer forms a band-like electrical flow path. A low-resistance portion having lower resistance than the heat-generating layer is provided to a joint end portion, which is an end portion of the heat-generating layer constituting an inlet side or an outlet side of the electrical flow path.

Description

Film-type heater

[0001] This disclosure relates to a film-type heater.

[0002] Several film-type heaters have been proposed conventionally.

[0003] Patent Document 1 describes a tape heater characterized in that a heating element is supported on a heat-resistant and flexible strip-shaped substrate with a defined heating surface, and the entire structure is encased in a heat-resistant resin sheet. It is stated that such a tape heater can be used for heat retention or heating of any type of piping, such as straight or curved pipes, of precision instruments and devices, and can be suitably used in clean rooms and the like where extremely low dust generation is required.

[0004] Japanese Patent Publication No. 2004-303580

[0005] A film-type heater is preferably characterized by minimal temperature distribution bias within its main surface. This disclosure provides a film-type heater characterized by minimal temperature distribution bias within its main surface.

[0006] This disclosure relates to a film-type heater including a heating layer, wherein when the main surface thereof is viewed from a perpendicular direction, the heating layer forms a strip-shaped electrical channel, and a low-resistance portion with lower resistance than the heating layer is attached to the junction end, which is the end of the heating layer that constitutes the inlet or outlet of the electrical channel.

[0007] Such a film-like heater will also be referred to as the "heater of this disclosure" below.

[0008] According to this disclosure, it is possible to provide a film-type heater in which the temperature distribution within its main surface is less uneven.

[0009] Figure 1(a) is a schematic diagram of the main surface of the heater of the present disclosure as viewed from the direction perpendicular to it, and Figure 1(b) is a cross-sectional view taken along line A-A in Figure 1(a). Figure 2(a) is a schematic diagram of the main surface of another heater of the present disclosure as viewed from the direction perpendicular to it, and Figure 2(b) is a cross-sectional view taken along line B-B in Figure 2(a). Figure 3 shows the state before the two heaters 1c and 1d of the present disclosure are connected, and is a schematic diagram of the main surface of each as viewed from the direction perpendicular to it. Figure 4 shows the state in which parts of the heaters 1c and 1d of the present disclosure shown in Figure 3 are superimposed and their low-resistance sections are connected by wiring, and is a schematic diagram of the main surface as viewed from the direction perpendicular to it.

[0010] The heater of this disclosure will be described with reference to the figures. The heater of this disclosure is not limited to the embodiments shown in the figures. All figures are schematic diagrams, and the dimensions and size of the heater of this disclosure may differ from those shown in the figures.

[0011] Figure 1(a) is a schematic view of the main surface of the heater of this disclosure as seen from the direction perpendicular thereto, and Figure 1(b) is a cross-sectional view taken along line A-A in Figure 1(a).

[0012] In Figure 1, the heater 1a of this disclosure has a heating layer 3, and insulating layers 5 and 7 are provided on both main surfaces of the heating layer 3. That is, the heating layer 3 is sandwiched between the two insulating layers 5 and 7. Preferably, at least one main surface of the heating layer 3 is covered by an insulating layer, and more preferably, both main surfaces of the heating layer 3 are covered by the two insulating layers 5 and 7, as shown in Figure 1. In Figure 1(a), the location of the heating layer 3 is indicated by a dotted line.

[0013] Furthermore, the heater in this disclosure does not necessarily have an insulating layer.

[0014] When the main surface of the heater 1a of this disclosure is viewed from a perpendicular direction, the heating layer 3 forms a strip-shaped electrical channel, as shown in Figure 1(a). Such a strip-shaped electrical channel can be formed by patterning, for example, metal foil, metal mesh, or metal fiber sheet. The shape of the electrical channel in the heating layer is not limited.

[0015] Here, the ends of the heating layer 3 that constitute the inlet side (electrical inlet side) or outlet side (electrical outlet side) of the electrical flow path are defined as the joint ends 31 and 33. Figure 1(a) shows the inlet joint end 31 and the outlet joint end 33.

[0016] In the embodiment shown in Figure 1, the inlet joint end 31 and the outlet joint end 33 are located adjacent to each other. However, the position of the joint ends is not particularly limited in the heater of this disclosure. Furthermore, the number of joint ends in the heater of this disclosure is not particularly limited. The number of inlet joint ends and the number of outlet joint ends may be different. In this case, the electrical flow path will branch off midway.

[0017] The heater 1a of this disclosure has a low-resistance portion 41a at the joint end 31 that has a lower resistance than the heating layer 3. Similarly, the joint end 33 has a low-resistance portion 43a that has a lower resistance than the heating layer 3. The method of attaching the joint end and the low-resistance portion is not particularly limited. For example, as shown in Figure 1(b), these ends can be joined by overlapping them and welding them together. Alternatively, as long as the joint end and the low-resistance portion are electrically connected, it may suffice to simply bring at least a portion of the joint end and the low-resistance portion into close contact. For example, by bringing at least a portion of the joint end and the low-resistance portion into close contact, covering both surfaces with an insulating layer, and bonding the two insulating layers, it is usually possible to maintain the state in which the joint end is attached to the low-resistance portion.

[0018] The shape of the low-resistance sections 41 and 43 is not limited. As shown in Figure 1, when the main surface of the heater 1a of this disclosure is viewed from the perpendicular direction, the low-resistance sections 41a and 43a are preferably strip-shaped. When the low-resistance sections 41a and 43a are strip-shaped, as shown in Figure 1, their longitudinal direction is preferably parallel to the longitudinal direction of the joint ends 31 and 33 to which they are connected. Here, parallel does not have to be perfectly parallel. For example, the angle between the line that bisects the width direction of the joint end and the line that bisects the width direction of the strip-shaped low-resistance section is preferably 5 degrees or less, and more preferably 3 degrees or less.

[0019] Furthermore, if the low-resistance sections 41a and 43a are in the shape of strips, the width of the strips of the low-resistance sections 41a and 43a (the length indicated by L in Figure 1(a)) is preferably 1 to 10 mm, more preferably 2 to 6 mm, and even more preferably 3 to 5 mm.

[0020] As described above, in Figure 1, the heater 1a of the present disclosure has insulating layers 5 and 7 on both main surfaces of the heating layer 3. However, as shown in Figure 1(a), it is preferable that at least a portion of the low-resistance portions 41a and 43a are covered by the two insulating layers 5 and 7. In such a case, the low-resistance portions are insulated, and in addition, the low-resistance portions covered by the insulating layers have high strength.

[0021] In the embodiment shown in Figure 1(a), two insulating layers 5 and 7 cover the heating layer 3 (including the joint ends 31 and 33), and also cover the low-resistance portions 41a and 43a. In other words, the insulating layer covering the heating layer 3 and the insulating layer covering the low-resistance portions 41 and 43 are continuous and integral. Here, "integral" means that they are not separated and can be recognized as one object. For example, when the heating layer 3 (including the joint ends 31 and 33) and the low-resistance portions 41a and 43a are sandwiched and covered by two insulating sheets, the insulating layers 5 and 7 are each integral. When the insulating layers are integral, the heater of this disclosure not only eliminates the need for insulating treatment of the joint area, but also suppresses the occurrence of rupture of the insulating layer, and can maintain more stable insulation.

[0022] In the heater 1a of this disclosure, terminals are connected to the low-resistance sections 41a and 43a, wiring extends from the terminals, the wiring is connected to a power supply, and electricity is supplied from the power supply to energize the heating layer 3, causing the heating layer 3 to generate heat. Although the terminals, wiring, and power supply mentioned herein are not shown in Figure 1, they may be conventionally known.

[0023] The method of connecting the low-resistance section and the terminal is not limited and may be a conventionally known method, for example. Specifically, the low-resistance section and the terminal can be connected by welding.

[0024] After connecting the low-resistance section to the terminal, the area around the connection point between the low-resistance section and the terminal may be covered with a fluorine-based heat-shrinkable tube.

[0025] As described above, Figure 1 shows an embodiment in which, when the main surface of the heater 1a of the present disclosure is viewed from a perpendicular direction, the low-resistance portions 41a and 43a are strip-shaped, and their longitudinal direction is parallel to the longitudinal direction of the joint ends 31 and 33. On the other hand, when the main surface of the heater of the present disclosure is viewed from a perpendicular direction, the low-resistance portions may extend in a direction parallel to the longitudinal direction of the joint ends, as shown in Figure 1, and then bend in a direction different from that direction.

[0026] This embodiment will be explained using Figure 2. Figure 2(a) is a schematic diagram of the main surface of the heater 1b of the present disclosure as viewed from the direction perpendicular to it, and Figure 2(b) is a cross-sectional view taken along line B-B in Figure 2(a). In the embodiment shown in Figure 2, when the main surface of the heater 1b of the present disclosure is viewed from the direction perpendicular to it, the low-resistance portions 41b and 43b extend in a direction parallel to the longitudinal direction of the joint ends 31 and 33, as in the embodiment shown in Figure 1, and then bend and extend in a direction perpendicular to that direction. In the embodiment shown in Figure 2, the low-resistance portions 41b and 43b are all covered with insulating layers 5 and 7. In this embodiment, as shown in Figure 2(b), the ends of the insulating layers 5 and 7 are peeled off from the low-resistance portions 41b and 43b, and terminals are connected thereto. Wiring extends from the terminals, the wiring is connected to a power supply, and it is preferable that electricity is supplied from the power supply to energize the heating layer 3, causing the heating layer 3 to generate heat.

[0027] Conventionally, in film heaters containing a heating layer forming a strip-shaped electrical channel, terminals were directly connected to the junction ends, which are the ends of the heating layer. Wiring was extended from the terminals and connected to a power supply to provide electricity to the heating layer. In this case, the temperature at the connection point between the heating layer and the terminals could be higher or lower than other parts. For example, if the film heater is placed on the surface of an object to be heated, and the connection point is located within the area where the film heater and the object to be heated are in contact, the temperature at that connection point tends to decrease. Conversely, if the connection point is located outside the area where the film heater and the object to be heated are in contact, the temperature at that connection point tends to increase. Furthermore, to counteract the increased temperature in certain areas, it was necessary to use an insulating layer (such as an insulating sheet) that could withstand high temperatures, which was disadvantageous in terms of cost. In contrast, the heater of this disclosure is less prone to temperature drops or increases at the connection point. This is thought to be because the junction end has a low-resistance section with lower resistance than the heating layer.

[0028] Next, an embodiment in which the two heaters 1c and 1d of this disclosure are connected will be described using Figures 3 and 4. In Figures 3 and 4, the heating layers 3c and 3d are shown by dotted lines. Figure 3 is a schematic diagram showing the state before the two heaters 1c and 1d of this disclosure are connected, and is a schematic diagram when the main surface is viewed from the perpendicular direction.

[0029] The heaters 1c and 1d of the present disclosure shown in Figures 3(a) and 3(b) have heating layers 3c and 3d, respectively, with insulating layers 9c and 9d on one main surface and insulating layers 9e and 9f on the other main surface.

[0030] As shown in Figures 3(a) and 3(b), the heaters 1c and 1d of this disclosure have heating layers 3c and 3d that form a strip-shaped electrical channel when their main surface is viewed from a perpendicular direction.

[0031] In the heater 1c of this disclosure shown in Figure 3(a), there are two ends of the heating layer 3c that constitute the inlet side of the electrical flow path, which are designated as joint ends 31c and 31d. There are also two ends of the heating layer 3c that constitute the outlet side of the electrical flow path, which are designated as joint ends 33c and 33d.

[0032] In the heater 1d of this disclosure shown in Figure 3(b), the end of the heating layer 3d that constitutes the inlet side of the electrical flow path is designated as a joint end 31e, and the end of the heating layer 3d that constitutes the outlet side of the electrical flow path is designated as a joint end 33e.

[0033] Furthermore, the joint ends 31c, 31d, 33c, 33d, 31e, and 33e are each fitted with low-resistance sections 41c, 41d, 43c, 43d, 41e, and 43e, respectively, which have lower resistance than these sections.

[0034] Figure 4 is a schematic diagram showing a view from the direction perpendicular to the main surface of the heaters 1c and 1d of this disclosure, with parts of each superimposed and their low-resistance sections connected by wiring.

[0035] Terminals (not shown) are connected to the low-resistance portion 43d of the heater 1c and the low-resistance portion 41e of the heater 1d of the disclosed invention, and wiring 51a connects these terminals. Furthermore, terminals (not shown) are connected to the low-resistance portion 41d of the heater 1c and the low-resistance portion 43e of the heater 1d of the disclosed invention, and wiring 53a connects these terminals. In addition, terminals (not shown) are connected to each of the low-resistance portions 41c and 43c of the heater 1c of the disclosed invention, and wiring 51b and 53b extend from these terminals, and each wiring is connected to a power supply. When electricity is supplied from the power source, the electricity supplied from the wiring 51b passes from the low-resistance section 41c through the joint end 31c, through the heating layer 3c, through the joint end 33d, through the low-resistance section 43d through the wiring 51a to reach the low-resistance section 41e, then through the joint end 31e to pass through the heating layer 3d, through the joint end 33e, through the low-resistance section 43e through the wiring 53a to reach the low-resistance section 41d, then through the joint end 31d to pass through the heating layer 3c, through the joint end 33c, and returns to the power source via the low-resistance section 43c through the wiring 53b. During this process, the heating layers 3c and 3d generate heat.

[0036] In the embodiment shown in Fig. 4, the bonding end 33d of the heater 1c of the present disclosure and the bonding end 31e of the heater 1d of the present disclosure are indirectly connected via the low-resistance portion and the wiring. In addition, the bonding end 31d of the heater 1c of the present disclosure and the bonding end 33e of the heater 1d of the present disclosure are indirectly connected via the low-resistance portion and the wiring. Here, each of the bonding ends may be directly connected to each other.

[0037] In the embodiment shown in Fig. 4, a part of each of the heater 1c of the present disclosure and the heater 1d of the present disclosure overlaps in the thickness direction. And one of the overlapping portions is a low-resistance portion. That is, the low-resistance portions 41d and 43d in the heater 1c of the present disclosure overlap with a part of the heat-generating layer 3d in the heater 1d of the present disclosure, and the low-resistance portions 41e and 43e in the heater 1d of the present disclosure overlap with a part of the heat-generating layer 3c in the heater 1c of the present disclosure. By adopting this configuration, the wirings 51a and 53a can be shortened, the gap between the heater 1c of the present disclosure and the heater 1d of the present disclosure can be reduced, and heat generation loss can be reduced. In addition, in this case, since the overlapping portion is a low-resistance portion, it is less likely to generate heat, and the temperature is less likely to rise. As a result, the temperature tends to be uniform within the heater of the present disclosure.

[0038] On the contrary, if the heater 1c of the present disclosure and the heater 1d of the present disclosure do not have a low-resistance portion, the amount of heat generated at the overlapping portion is higher than that at other portions, so the temperature also becomes higher. That is, it is difficult for the temperature to be uniform within the film heater.

[0039] <Heat-generating layer> The heat-generating layer included in the heater of the present disclosure will be described. The heat-generating layer is a sheet-shaped member that generates heat when energized. Also, as described above, it is preferably formed by patterning so as to serve as a band-shaped electrical flow path. Further, the heat-generating layer may be one in which wires made of heat-generating metal such as nichrome wire are arranged so as to form a layer as a whole.

[0040] The heat-generating layer may be, for example, a metal foil, a sheet-shaped metal mesh, a sheet-shaped metal fiber, or a carbon sheet.

[0041] The material of the heating layer is not particularly limited as long as it generates heat when electricity is passed through it. Stainless steel is preferred due to its high heat resistance and chemical resistance, but Cu (copper), Al (aluminum), Ni (nickel), nichrome, or carbon may also be used.

[0042] The thickness of the heating layer is preferably 20 to 250 μm, and more preferably 30 to 150 μm.

[0043] The thickness of the heating layer is determined as follows: First, a cross-section of the heater of this disclosure is obtained in a direction parallel to the perpendicular to the main surface. Next, a magnified photograph (200x) of the cross-section is obtained using an optical microscope, and the thickness of the heating layer is measured at 30 randomly selected locations in the magnified photograph, and the simple average value of these measurements is calculated. The obtained simple average value is then taken as the thickness of the heating layer. In this disclosure, the thickness of elements other than the heating layer is determined by the same method.

[0044] The shape and size of the main surface of the heating layer can be appropriately adjusted to match the shape and size of the object to be heated on which the heater of this disclosure is installed.

[0045] The resistance of the heating layer is preferably between 5 and 800 Ω, and more preferably between 10 and 300 Ω. If this resistance is too low, there is a possibility of excessive power output leading to excessive temperature, and conversely, if the resistance is too high, there is a possibility of insufficient power output leading to a long time for the temperature to rise. Here, the resistance of the heating layer shall be the value determined in accordance with JIS C 2525.

[0046] The sheet resistance of the heating layer is preferably 0.01 to 0.3 Ω / □, more preferably 0.05 to 0.25 Ω / □, and even more preferably around 0.065 Ω / □. The sheet resistance of the heating layer shall be the value obtained by measurement in accordance with JIS K 7194.

[0047] The heating layer is preferably composed mainly of sheet-like metal fibers or sheet-like metal mesh using metal fibers, and more preferably composed solely of sheet-like metal mesh. Here, "mainly" means 70% by mass or more. That is, it is preferable that 70% by mass or more of the heating layer is metal fibers. It is more preferable that the proportion of metal fibers in the heating layer be 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0048] The proportion of metal fibers contained in the heating layer shall be determined by the following method: The surface of the heating layer is magnified 1,000 times using a scanning electron microscope (SEM) to obtain an SEM image. The area occupied by metal fibers (excluding voids) within the field of view is determined using an image processing device, converted to a volume ratio by raising it to the power of 3 / 2, and then multiplied by the specific gravity to obtain a mass ratio, thereby calculating the metal fiber content.

[0049] The metal mesh is preferably made of stainless steel due to its high heat resistance and chemical resistance. The weaving method of the metal mesh is not particularly limited and may be plain weave, twill weave, plain tatami weave, or twill tatami weave, but plain weave is more preferable.

[0050] The mesh size of the metal mesh is preferably 16 to 800 mesh, more preferably 150 to 280 mesh, and preferably around 200 mesh.

[0051] The metal fibers used in the sheet-like metal mesh preferably have a fiber diameter of 0.01 to 0.1 mm, and more preferably 0.03 mm to 0.06 mm. Furthermore, the metal mesh is preferably constructed as a sheet (metal mesh sheet) by weaving such metallic fibers. Here, the metal mesh sheet may consist only of metal fibers, but it may also include non-metallic fibers (for example, resin fibers that function as a binder) in addition to metal fibers, to the extent that it does not hinder heat generation.

[0052] Metal mesh sheets have a basis weight of 150 to 1300 g / m². 2preferably 150 to 300 g / m 2 and more preferably . The basis weight shall be a value determined in accordance with JIS P 8124.

[0053] The density of the metal mesh sheet is 1 to 6 g / cm 3 preferably 2 to 5 g / cm 3 and more preferably . The density of the metal mesh sheet is determined in accordance with JIS P 8118, and the density (g / cm 3 ) = basis weight (g / m 2 ) / (thickness (mm) × 1000).

[0054] The metal fibers used as the sheet-shaped metal fibers are preferably metal fibers having an equal-area circle equivalent diameter of a cross section of 2 to 100 µm (preferably 5 to 20 µm) and a length of 2 to 20 mm. The equal-area circle equivalent diameter means the diameter of a circle having the same area as the area of the cross section. Further, the heat generating layer is preferably configured in a sheet shape by countless such metallic fibers intricately entangled with each other (metal fiber sheet). Here, the metal fiber sheet may consist only of metal fibers, but in addition to metal fibers, it may also contain components other than metal fibers (for example, resin fibers having a function as a binder) within a range that does not impair heat generation properties. Here, the metal fibers constituting the metal fiber sheet are in contact with each other to an extent that allows current conduction. It is preferable that the metal fibers are connected to each other at the contact points. For example, it is preferable that the metal fibers are fused to each other at the contact points by having a history of solidification after a part of the metal fibers is melted by sintering at a high temperature.

[0055] The metal fiber sheet is preferably a SUS fiber sheet because of its high heat resistance and chemical resistance. Examples of the SUS fiber sheet include stainless steel fiber sheets (e.g., Tommy Fyrecc SS, manufactured by Tomoegawa Paper Co., Ltd.).

[0056] The basis weight of the metal fiber sheet is 25 g / m 2 or more, preferably 50 g / m 2 or more. Further, it is preferably 1000 g / m 2 or less, more preferably 200 g / m 2The following is more preferable. The basis weight shall be the value obtained in accordance with JIS P 8124.

[0057] The density of the metal fiber sheet is 1.0 to 10.0 g / cm³. 3 Preferably, it is 1.4 to 2.0 g / cm³. 3 It is more preferable that the concentration be 1.7 g / cm³. 3 It is preferable that the density is within a certain range. The density of the metal fiber sheet shall be in accordance with JIS P 8118, with a density of (g / cm³). 3 )=Basic weight (g / m 2 The value obtained by ) / (thickness (mm) × 1000) shall be used.

[0058] Metal fiber sheets can be manufactured by either a dry-laid nonwoven fabric manufacturing method or a wet-laid papermaking method. When manufactured by the wet-laid papermaking method, countless metallic fibers with an equivalent diameter of 2 to 100 μm and a length of 2 to 20 mm are stirred in a dispersion medium (water, organic solvent, etc.), then an organic flocculant is added, and the sheet is formed using a rectangular papermaking machine (such as those manufactured by Toyo Seiki Co., Ltd.), and then dried using a ferrotype drying device until the basis weight is 50 to 1100 g / m². 2 A dried sheet is obtained. Then, by firing at 400 to 1300°C, a metal fiber sheet is obtained. In principle, it is preferable that no organic flocculant remains in the metal fiber sheet.

[0059] <Low-resistance section> The low-resistance section in this disclosure will now be described. The low-resistance section only needs to have a lower resistance than the heating layer, and its material, shape, size, etc., are not limited and may be the same as those of the heating layer. The ratio of the sheet resistance values ​​(low-resistance section / heating layer) is preferably 0.01 to 0.1, and more preferably 0.01 to 0.05. The resistance referred to here means the sheet resistance value measured according to JIS K 7194.

[0060] The material of the low-resistance section may be the same as the material of the heating layer. Preferably, the material of the low-resistance section is stainless steel foil.

[0061] The thickness of the low-resistance section is preferably 50 to 200 μm, and more preferably 80 to 120 μm.

[0062] Preferably, the thickness of the aforementioned heating layer is 20 to 250 μm, and the thickness of the low-resistance portion is 50 to 200 μm.

[0063] <Wiring> The wiring in the heater of this disclosure will now be described. When connecting the low-resistance section of the heater of this disclosure to a power supply by wiring, terminals located at the ends of the wiring are usually connected to the low-resistance section. However, terminals are not mandatory, and the ends of the wiring may be connected directly to the low-resistance section.

[0064] The wiring can be made of any conductive material, such as Cu (copper), Al (aluminum), Ni (nickel), nichrome, or carbon.

[0065] The length and thickness of the wiring are not particularly limited. The thickness (cross-sectional diameter) may be, for example, 0.5 to 2.0 mm.

[0066] Wiring can be made of solid wire or processed wire (spiral processing, rolling processing, stranding processing). Bare wire or insulated wire can be used as wiring. Stranded wire is preferable for wiring. Wiring is preferably highly flexible. Stranded wire as wiring has excellent flexibility.

[0067] <Insulating Layer> The heater of the present disclosure may have an insulating layer. If the heater of the present disclosure has multiple insulating layers, these may be identical in form or different in form.

[0068] The insulating layer serves to electrically insulate the heating layer from the surrounding components. Preferably, the insulating layer possesses both insulating and thermal conductivity.

[0069] The insulating layer is preferably made of materials such as PET (polyethylene terephthalate), PI (polyimide), PP (polypropylene), PE (polyethylene), PEN (polyethylene naphthalate), TAC (triacetylcellulose), or ceramic. This is because these materials have high insulating properties. Among these, an insulating layer made of PI (polyimide) is preferred because it has excellent heat resistance and insulating properties.

[0070] The thickness of the insulating layer is not limited, but is preferably 25 to 500 μm, and more preferably 50 to 200 μm.

[0071] The shape and size of the main surface of the insulating layer are not particularly limited. However, since the insulating layer serves to electrically insulate the heating layer from other layers, the size of the main surface of the insulating layer is usually the same as or larger than the main surface of the heating layer.

[0072] <Sheet-like Substrate> The heater of this disclosure may include a sheet-like substrate. The sheet-like substrate is preferably made of a material that has insulating properties and flexibility, such as PET (polyethylene terephthalate), PI (polyimide), PP (polypropylene), PE (polyethylene), PEN (polyethylene naphthalate), or TAC (triacetylcellulose). The sheet-like substrate may also be made of a fluororesin. Examples of fluororesins include polytetrafluoroethylene (PTFE), vinylidene fluoride-hexafluoropropylene copolymer, and vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer. Furthermore, the sheet-like substrate may be a high-strength, high-insulating sheet made by impregnating glass, aramid (aromatic polyamide resin), carbon fiber, or other reinforcing fibers with a fluororesin. The sheet-like substrate is installed on a surface outside the insulating layer. Furthermore, the sheet-like substrate may be installed on a surface that is outside the insulating layer on one side of the heater's two main surfaces, or on a surface that is outside the insulating layer on both sides.

[0073] The thickness of the sheet-like substrate is not particularly limited, but is preferably 25 to 500 μm, and more preferably 50 to 200 μm.

[0074] <Adhesives> The insulating layer and the heating layer may be bonded together using an adhesive. Furthermore, a sheet-like substrate may be attached to the main surface of the insulating layer that is not in contact with the heating layer using an adhesive. Examples of adhesives that can be used in the heater of this disclosure include acrylic adhesives, silicone adhesives, rubber elastomers, thermosetting adhesives, thermoplastic adhesives, and fluorine-based adhesives. Alternatively, an adhesive sheet made of the same material can be used instead of an adhesive.

[0075] <Thermal insulation layer> When the heater of this disclosure is installed on the surface of an object to be heated (e.g., a pipe), it is preferable that the outer circumference of the heater of this disclosure is covered with a thermal insulation layer.

[0076] Examples of insulating materials that make up the insulation layer include fibrous insulating materials (such as glass wool, rock wool, cellulose fiber, and wool breath) and foamed insulating materials (such as urethane foam, phenolic foam, melamine foam, Teflon foam, and polyimide foam).

[0077] The thickness of the thermal insulation layer is not particularly limited, but is preferably 15 to 100,000 μm, more preferably 30 to 50,000 μm, and even more preferably 6,000 to 25,000 μm.

[0078] The present disclosure includes the following embodiments (1) to (6): (1) A film-like heater including a heating layer, wherein when its main surface is viewed from a perpendicular direction, the heating layer forms a strip-shaped electrical channel, and a low-resistance portion with lower resistance than the heating layer is attached to the junction end, which is the end of the heating layer that constitutes the inlet or outlet of the electrical channel. (2) The film-like heater according to (1), wherein the junction end and the low-resistance portion connected thereto are covered with an insulating layer. (3) The film-like heater according to (2), wherein the heating layer is further covered with the insulating layer, and the insulating layer is integral with the heating layer. (4) The film-like heater according to any one of (1) to (3), wherein a terminal is connected to the low-resistance portion, wiring extends from the terminal, the wiring is connected to a power source, and the heating layer is energized and generates heat when electricity is supplied from the power source. (5) A film heater according to any one of (1) to (4) above, wherein the low-resistance portion is directly or indirectly connected to the joint end of another film heater. (6) A film heater according to any one of (1) to (5) above, wherein the thickness of the heating layer is 20 to 250 μm and the thickness of the low-resistance portion is 50 to 200 μm. (7) A film heater according to any one of (1) to (6) above, wherein the low-resistance portion is in the shape of a strip, its longitudinal direction is parallel to the longitudinal direction of the joint end to which it is connected, and the width of the strip of the low-resistance portion is 1 to 10 mm.

[0079] This application claims priority based on Japanese Patent Application No. 2025-53630, filed on 27 March 2025, and incorporates all of its disclosures herein.

[0080] 1a, 1b, 1c, 1d Heater of the present disclosure 3, 3c, 3d Heating layer 31, 33, 31c, 33c, 31e, 33e Joint end 5, 7, 9c, 9d Insulating layer 41a, 41b, 41c, 41d, 41e Low resistance section 43a, 43b, 43c, 43d, 43e Low resistance section 51a, 53a, 51b, 53b Wiring

Claims

1. A film-type heater including a heating layer, wherein when its main surface is viewed from a perpendicular direction, the heating layer forms a strip-shaped electrical channel, and a low-resistance portion with lower resistance than the heating layer is attached to the junction end, which is the end of the heating layer that constitutes the inlet or outlet of the electrical channel.

2. The film heater according to claim 1, wherein the joint end and the low-resistance portion connected thereto are covered with an insulating layer.

3. The film-type heater according to claim 2, wherein the heating layer is further covered by the insulating layer, and the insulating layer is integral with the heating layer.

4. The film-type heater according to claim 1 or 2, wherein a terminal is connected to the low-resistance portion, a wire extends from the terminal, the wire is connected to a power supply, and the heating layer is energized and generates heat when electricity is supplied from the power supply.

5. The film heater according to claim 1 or 2, wherein the low-resistance portion is directly or indirectly connected to the joint end of another film heater.

6. The film-type heater according to claim 1 or 2, wherein the thickness of the heating layer is 20 to 250 μm and the thickness of the low-resistance portion is 50 to 200 μm.

7. The film-type heater according to claim 1 or 2, wherein the low-resistance portion is in the shape of a strip, its longitudinal direction is parallel to the longitudinal direction of the joint end to which it is connected, and the width of the strip of the low-resistance portion is 1 to 10 mm.

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