Planar heater

Abstract

A planar heater (10) includes: a heat-insulating base material (1); a metal-coated base material (3) provided on the heat-insulating base material; a string-shaped heat generator (5) provided closer to the metal-coated base material than the heat-insulating base material; and a black heat-fusion layer (4) provided adjacent to the string-shaped heat generator.

Description

Technical Field

[0001] This invention relates to planar heaters. Background Technology

[0002] Generally, surface heaters that fix rope-like heating elements to various substrates are known. These surface heaters can also be used, for example, in automotive seat heaters. One type of such surface heater has a structure in which the rope-like heating element is coiled and arranged on an insulating substrate such as non-woven fabric or polyurethane foam and sewn to the substrate. Another type of surface heater has a structure in which the rope-like heating element with a heat-fusion layer on its surface is coiled and arranged on a substrate with a heat-fusion layer on its surface, and then fused and fixed to the substrate by heat pressing. An example of this type of surface heater is disclosed, for example, in Japanese Patent Application Publication No. 2014-127230. When these surface heaters are used as seat heaters, they are positioned, for example, between an insulating seat cushion and a cover. Depending on their application, these surface heaters require various properties such as bending durability, instant heating, heating uniformity, energy efficiency, and tactile comfort. Summary of the Invention

[0003] The purpose of this invention is to provide an excellent planar heater.

[0004] According to one embodiment of the present invention, the planar heater comprises: an insulating substrate, a metal coating substrate disposed on the insulating substrate, a rope-shaped heating element disposed closer to the metal coating substrate than the insulating substrate, and a black heat-fusion layer disposed adjacent to the rope-shaped heating element.

[0005] According to the present invention, an excellent planar heater can be provided. Attached Figure Description

[0006] Figure 1A This is a schematic top view showing an overview of the structure of the stitched planar heater of the first embodiment.

[0007] Figure 1B To illustrate along Figure 1A A schematic diagram of the cross-section of the stitched planar heater along the IB-IB line.

[0008] Figure 1C The diagram, which schematically illustrates the structure of an example of a rope-shaped heating element according to a certain embodiment, shows a state in which part of the insulating coating layer has been removed and part of the bare stranded wire has been untied.

[0009] Figure 1D This is a schematic diagram showing a cross-section of an example of a bare stranded wire according to one embodiment.

[0010] Figure 2AThis is a schematic top view showing an overview of the structure of the joint-type planar heater of the second embodiment.

[0011] Figure 2B To illustrate along Figure 2A A schematic diagram of the cross-section of the junction type planar heater shown in the IIB-IIB line.

[0012] Figure 3A This is a schematic top view showing an overview of the structure of the covered planar heater of the third embodiment.

[0013] Figure 3B To illustrate along Figure 3A A schematic diagram of the cross-section of the encapsulated planar heater of line IIIB-IIIB. Detailed Implementation

[0014] The embodiments will be described with reference to the accompanying drawings. This embodiment relates to a surface heater, for example, that can be used as a seat heater. The surface heater of this embodiment not only employs a rope-shaped heating element, which provides reliability and cost-effectiveness as a seat heater for long-term use, but also possesses the advantages of various surface heaters. The surface heater of this embodiment exhibits excellent energy-saving performance.

[0015] [Stitched surface heater]

[0016] [Structure Overview]

[0017] The first embodiment relates to a stitched surface heater. Figure 1A This is a schematic top view showing an overview of the structure of the planar heater 10 in this embodiment. Figure 1B To indicate along Figure 1A A schematic cross-sectional view of the cross-section of the planar heater 10 along the IB-IB line shown.

[0018] The planar heater 10 has a structure in which a rope-shaped heating element 5 is fixed on a heating wire holding substrate 11. The heating wire holding substrate 11 has a structure in which an insulating substrate 1, an adhesive layer 2, an aluminum coating substrate 3, and a black heat-fusion layer 4 are stacked in sequence. The heating wire holding substrate 11 is formed by integrating the insulating substrate 1 and the aluminum coating substrate 3 with an adhesive, then depositing the black heat-fusion layer 4 on the surface of the aluminum coating substrate 3, and heat-fusion bonding the black heat-fusion layer 4 on the surface of the aluminum coating substrate 3 by hot pressing or the like. Alternatively, the insulating substrate 1, adhesive, aluminum coating substrate 3, and black heat-fusion layer 4 can be deposited together and then heat-fused. In either case, the aluminum coating substrate 3 is disposed on the insulating substrate 1. The black heat-fusion layer 4 is a carbon-containing black heat-fusion layer.

[0019] The rope-shaped heating element 5 is fixed to the black heat-fused layer 4 of the heating wire holding substrate 11. The rope-shaped heating element 5 is fixed to the heating wire holding substrate 11 by stitching together the upper thread 6a and the lower thread 6b. For example, the rope-shaped heating element 5 is laid out on the surface of the black heat-fused layer 4 of the heating wire holding substrate 11 according to the pattern and / or program of an automatic sewing machine, and then stitched together with the upper thread 6a and the lower thread 6b using a houndstooth stitch, thereby fixing the rope-shaped heating element 5 to the heating wire holding substrate 11. In this way, the black heat-fused layer 4 is placed adjacent to the rope-shaped heating element 5. By appropriately adjusting the sewing speed, seam width, and seam tension, the strength and slack of fixing the rope-shaped heating element 5 can be adjusted. When the surface heater 10 is used as a seat heater, the downward deformation stress caused by the user sitting down can be alleviated by the slippage and misalignment of the rope-shaped heating element 5. With this structure, higher durability can be obtained.

[0020] [Details of each part]

[0021] The details of each part of the surface heater 10 will now be explained.

[0022] <Insulation Substrate and Adhesive>

[0023] Various materials such as polyurethane foam, non-woven fabric, and felt can be used as the material for the insulation substrate 1. Since the flatness of the bonding between the insulation substrate 1 and the aluminum-coated substrate 3 is high, the formation of wrinkles after bonding is suppressed. Therefore, it is preferable to use materials that emphasize surface smoothness as the material for the insulation substrate 1.

[0024] The adhesive used to bond the heat-insulating substrate 1 to the aluminum-coated substrate 3 requires heat resistance and flame retardancy. Furthermore, when the surface heater 10 is used as a seat heater, a soft adhesive is preferred. Using an adhesive that hardens after curing results in a stiff feeling upon sitting, which can cause discomfort for the user.

[0025] <Aluminum Coated Substrate>

[0026] The aluminum-coated substrate 3 is an article on which an aluminum film is applied to a flexible and durable material. As the material, woven fabrics, non-woven fabrics, polymer films, etc., can be used. The aluminum film is applied by, for example, vacuum evaporation, sputtering, plasma spraying, etc. In the case of vacuum evaporation, aluminum is deposited at the atomic level, thus the formed aluminum film becomes dense, which is preferable from a thermal conductivity perspective. Sputtering and plasma spraying have high layering speeds, so although the formed aluminum film is fine, it is deposited in a granular manner. Therefore, from a thermal conductivity perspective, vacuum evaporation is preferred.

[0027] The thickness of the aluminum film is 5μm to 50μm, preferably 10μm to 15μm. Below 5μm, the thermal conductivity decreases. Above 50μm, the aluminum film is easily peeled off, and the production output per unit time is relatively low, increasing costs.

[0028] In the case of vacuum evaporation of aluminum, a textile with excellent flatness is preferred as the material. Among textile materials, plant fibers are preferred over petrochemical fibers. Commonly used and inexpensive cotton fabrics are particularly preferred. Among cotton fabrics, a soft and lustrous material, similar to a plain-weave shirt, is preferred for obtaining a thin aluminum vapor-deposited film. Petrochemical fibers, due to the strong tensile force applied during spinning, tend to shrink along their length when heated during heater operation, easily causing material deformation.

[0029] Aluminum-coated cotton fabric is sold as a quick-heating / heat-spreading cover, for example, for ironing tables. Such aluminum-coated cotton fabric does not shrink at high temperatures and has good thermal conductivity.

[0030] In the case of vacuum evaporation of aluminum, if the material is ordinary nonwoven fabric, the shadowed areas from the evaporation source increase, making it difficult to form a uniform evaporation film. However, in recent years, with the popularization of nonwoven masks, a technology has been developed that, although relatively expensive, can achieve a smooth surface on nonwoven fabric through special processes. Such smoothed nonwoven fabrics can achieve sufficiently uniform aluminum evaporation. Smoothed nonwoven fabrics are also a preferred material. Although nonwoven fabric is a petrochemical fiber, because it is a short fiber with a random arrangement of short fibers, the shrinkage of individual short fibers has little impact on the overall structure, making it less prone to material deformation.

[0031] Furthermore, as described above, the insulating substrate 1 can also be a nonwoven fabric. Therefore, a typically thicker and inexpensive nonwoven insulating substrate 1 can be bonded to an aluminum-coated substrate 3, which has aluminum oxide deposited on a nonwoven material that, although more expensive, has a smooth surface. Furthermore, as long as thick nonwoven fabric with a smooth surface is readily available at low cost, an article obtained by vacuum vapor deposition of aluminum on a thick nonwoven fabric with a smooth surface can be used instead of the insulating substrate 1, the bonding layer 2, and the aluminum-coated substrate 3. That is, the insulating substrate and the aluminum-coated substrate disposed on the insulating substrate can also be integrally formed as a nonwoven fabric with an aluminum coating formed on its surface.

[0032] In addition, when vacuum evaporation is performed on aluminum, problems with the bonding strength or thermal shrinkage relative to deformation stress can easily occur when the material is a polymer film.

[0033] Furthermore, the aluminum-coated substrate 3 is not limited to articles on which an aluminum film has been applied to the material. The aluminum-coated substrate 3 can also be, for example, a textile fabric formed from aluminum-coated long fibers.

[0034] In addition, the aluminum-coated substrate 3 can also be a metal-coated substrate containing other suitable metals to replace aluminum. For example, silver or copper can be used instead of aluminum.

[0035] <Black hot-melt layer>

[0036] The black heat-welding layer 4 of this embodiment is obtained by mixing polyolefin resin, carbon particles, and several additives, and then molding it into a thin film using a biaxial stretching device. Ceramic powder can be used instead of carbon particles, or ceramic powder can be used in addition to carbon particles. The black heat-welding layer 4 has a heat-welding function. The black heat-welding layer 4 prevents the aluminum film of the aluminum-coated substrate 3 from peeling off and provides safety to the surface heater 10. Furthermore, the black heat-welding layer 4 imparts far-infrared radiation to the surface heater 10. Utilizing this far-infrared radiation function, the surface heater 10 can heat the object not only through heat conduction but also through thermal radiation such as far-infrared rays. As a result, the thermal efficiency of the surface heater 10 can be improved, achieving energy-saving effects.

[0037] As polyolefin resins, two or more polyolefin resins or olefin copolymers can be used alone or in combination. Examples of polyolefin resins that can be used include polyethylene, polypropylene, and polybutene. Polyethylene includes high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. As olefin copolymers, copolymers of ethylene with propylene, vinyl acetate, acrylic acid, ethyl acrylate, vinyl chloride, etc., copolymers of propylene with vinyl chloride, or modified forms of these copolymers can be used.

[0038] As for the polyolefin resin used in this embodiment, considering factors such as melting point, heat-welding properties, and price, low-density polyethylene and linear low-density polyethylene are particularly preferred.

[0039] As carbon particles, various products can be used. For example, carbon black particles (oil furnace black, thermal black, acetylene black), graphite particles, etc., can be used alone, or they can be combined as a mixture.

[0040] The average particle size of the carbon particles is preferably 10 nm to 100 nm. Generally, a stable resistivity value can be obtained when the average particle size is 10 nm to 100 nm. The average particle size is more preferably 20 nm to 50 nm. When the average particle size is less than 10 nm, the dispersibility in the resin is poor, easily leading to impedance and color inhomogeneity. On the other hand, when the average particle size exceeds 100 nm, it tends to result in higher surface resistivity and increased surface resistivity deviation, easily causing unevenness in surface gloss. The carbon particles can also be a mixture obtained by mixing two or more carbon particles with different average particle sizes.

[0041] The mixing ratio of polyolefin resin and carbon particles is preferably adjusted to achieve a surface resistivity of 10. 5 Ω / cm 2 ~10 10 Ω / cm 2 To obtain such a surface resistivity, the proportion relative to the total weight of the black heat-fused layer 4 is set, for example, 60-95% by weight of polyethylene resin and 40-5% by weight of carbon particles. Preferably, the proportion of polyethylene resin is 80-90% by weight and the proportion of carbon particles is 20-10% by weight. A resin composition with this mixing ratio can be easily obtained by appropriately mixing polyethylene resin with a commercially available carbon-color compound. When the proportion of carbon particles is high, the total amount of far-infrared radiation increases. On the other hand, when the proportion of carbon particles is high, the heat-fused strength with the aluminum-coated substrate 3 weakens, and the insulation deteriorates. Furthermore, when the proportion of carbon particles is low, not only is the amount of far-infrared radiation less, but the antistatic function described later is also weakened, which is therefore undesirable.

[0042] To achieve both the objectives of preventing the micro-aluminum flakes from peeling off the aluminum-coated substrate 3 and far-infrared emission, the thickness of the black heat-fused layer 4 is preferably 0.05 mm to 0.35 mm, more preferably 0.08 mm to 0.15 mm. When the thickness of the black heat-fused layer 4 is less than 0.05 mm, the surface is rough after heat-fused to the aluminum-coated substrate 3, which is not preferable in preventing the micro-aluminum flakes from peeling off. When the thickness of the black heat-fused layer 4 is greater than 0.35 mm, the rise time during heating becomes longer, overshoot increases, and power consumption also increases, which is also undesirable.

[0043] The black hot-melt layer 4 is formed, for example, by mixing a commercially available carbon-pigment composite with polyethylene resin as described above, and then molding it into a thin film using a biaxial stretching device. The black hot-melt layer 4 is disposed on the aluminum-coated substrate 3 and is hot-melt bonded to the surface of the aluminum-coated substrate 3 using a hot-pressing device or the like. The hot-melt bonding can be performed using a continuous heating roller device or the like.

[0044] In addition, for example, when the surface heater 10 is used as a seat heater and the pressure generated by sitting down is large, a carbon-free homogeneous polyolefin resin film can be superimposed on the black heat-fusion layer 4 for heat fusion, thereby enhancing the mechanical stress.

[0045] Rope-shaped heating element

[0046] Figure 1C The diagram schematically illustrates the structure of one example of the rope-shaped heating element 5, showing the state after removing part of the insulating coating layer 53 and untying part of the bare stranded wire 52. For example... Figure 1CAs shown, the rope-shaped heating element 5 has 3 to 6 bare strands 52 aligned and spirally wound around the core 51 at appropriate intervals, and an electrically insulating covering layer 53 is formed around it.

[0047] The core 51 can be made of polyester fiber, aromatic polyamide fiber, or fully aromatic polyester fiber. For example, as an aromatic polyamide fiber, fiber with the trade name "Kevlar" can be used, and as a fully aromatic polyester fiber, fiber with the trade name "Vectran" can be used. For example, the core of a general-purpose surface heater uses a bundle of polyester fibers that are cost-effective. Furthermore, for example, the core for a seat heater uses a bundle of fully aromatic polyester fibers with a fineness of around 560 dtex and an outer diameter of 0.2 mm to 0.3 mm. Although fine, fully aromatic polyester fibers have strength and excellent heat resistance.

[0048] Figure 1D This is a schematic diagram showing a cross-section of an example of a bare stranded wire 52. The bare stranded wire 52 has a structure in which 2 to 3 bare resistance wires 521 containing 0.3% copper and tin and having an outer diameter of 0.05 mm to 0.08 mm are twisted together, and a polyurethane resin coating layer 522 is provided on its surface.

[0049] The thickness of the insulating coating layer 53 is, for example, 0.1 mm to 0.2 mm. The insulating coating layer 53 is formed of resins such as tetrafluoroethylene / ethylene copolymer (ETFE) and tetrafluoroethylene / hexafluoropropylene copolymer (FEP).

[0050] In the cord-shaped heating element 5 with the above-described structure, for example, by using fully aromatic polyester fiber in the core 51, the core 51 is thin yet heat-resistant; for example, by using fluororesin in the insulating coating layer 53, the insulating coating layer 53 is thin yet possesses excellent heat resistance and strength. Therefore, the cord-shaped heating element 5 can be designed to be sufficiently thin. Even if the cord-shaped heating element 5 is very thin, it is possible to prevent the bare resistance wire 521 from breaking due to mechanical stress when seated. Furthermore, since the cord-shaped heating element 5 is sufficiently thin, it is possible to sufficiently suppress user discomfort caused by the unevenness of the cord-shaped heating element 5.

[0051] Another example of the rope-shaped heating element 5 in this embodiment is described below. The rope-shaped heating element 5 can also be, for example, a single bare resistance wire, obtained by coating the surface of a 3% silver-copper alloy wire with an outer diameter of approximately 0.06 mm with an electrically insulating material such as polyurethane resin with a thickness of several μm, and then twisting approximately 20 of them together to form a product with an outer diameter of approximately 0.4 mm. The 3% silver-copper alloy wire has high strength and can sufficiently withstand the mechanical stress when seated, even without an intermediate element such as a core, ensuring safety with only a very thin single insulation layer. Rope-shaped heating elements with such a structure are generally referred to as single-insulation type rope-shaped heating elements. With this structure, the outer diameter of the rope-shaped heating element 5 can be reduced, and discomfort when seated can be suppressed. On the other hand, 3% silver-copper alloy wire is expensive.

[0052] [About planar heaters]

[0053] The planar heater 10 of this embodiment has excellent safety, instantaneous heating, uniform heating and energy saving.

[0054] It is known that surface heaters are previously developed by directly sewing and fixing rope-shaped heating elements to insulating substrates such as non-woven fabric or polyurethane foam. In these surface heaters, although the temperature of the rope-shaped heating element itself rises rapidly, the surface heater as a whole is difficult to heat up or cool down due to the high porosity and low thermal conductivity of the insulating substrate. In temperature control of these surface heaters, even when powered at maximum output power, the initial temperature rise after power-on is slow, requiring a considerable amount of time to reach the set temperature. Furthermore, due to the high overall insulation performance of the heater, even after the set temperature is reached and the input power is cut off using a temperature controller after power-on, the temperature may continue to rise, resulting in a temperature rise exceeding the set temperature, known as overshoot. Therefore, power consumption increases. Additionally, while more complex temperature control devices have been considered to suppress overshoot, this would lead to increased costs, reduced robustness, and a longer time required to reach the set temperature.

[0055] In contrast, the planar heater 10 of this embodiment has an aluminum-coated substrate 3 on the heating wire holding substrate 11. Because the aluminum-coated substrate 3 has a high thermal conductivity, the temperature rise of the planar heater 10 is faster, and power consumption is reduced. Furthermore, the improved temperature responsiveness of the planar heater 10 makes temperature control easier and suppresses overshoot. For these reasons, the planar heater 10 with the aluminum-coated substrate 3 can achieve energy savings.

[0056] The planar heater 10 of this embodiment has a black heat-fusion layer 4 on the heating wire holding substrate 11. The black heat-fusion layer 4 has the following four advantages.

[0057] (1) The black heat-fusion layer 4 contained in the heating wire holding substrate 11 does not cause any obstruction when sewing the rope-shaped heating element 5, and can function as a heat-fusion material when joining the rope-shaped heating element 5 to the heating wire holding substrate 11. Therefore, the black heat-fusion layer 4 can improve the design freedom of the planar heater 10.

[0058] (2) The black heat-welded layer 4 prevents tearing and / or peeling of the aluminum film on the aluminum-coated substrate 3 relative to repeated applied loads. For example, in the case where the surface heater 10 is used as a seat heater, the black heat-welded layer 4 prevents tearing and / or peeling of the aluminum film on the aluminum-coated substrate 3 relative to repeated sitting pressure. Therefore, the black heat-welded layer 4 helps to prevent, for example, hazards to human health, electrical interference, etc.

[0059] (3) The far-infrared radiation of the black heat-fused layer 4 is utilized to effectively utilize the released heat energy and achieve energy-saving effects. For example, when the surface heater 10 is used as a seat heater, the operating temperature range is usually set to 40-50°C. When carbon is heated within this temperature range, it will efficiently emit far-infrared radiation. As a result, the radiation in the wavelength range that is almost imperceptible to the human body is reduced, while the radiation in the wavelength range that is effective for heating the human body is increased.

[0060] (4) The black heat-fusion layer 4 can be used with rope-shaped heating elements that have been used for many years and whose reliability has been established. As a result, a high cost-performance ratio can be achieved.

[0061] It is known that aluminum foil heaters are obtained by fixing a rope-shaped heating element to an aluminum foil substrate. Aluminum foil heaters are known to have good instantaneous and uniform heating properties, and can be used as heaters for applications such as defrosting refrigerators, snow melting, cooking rice in rice cookers, or keeping rice warm.

[0062] However, if the aluminum foil heater is repeatedly subjected to impact loads, the aluminum foil may crack, resulting in the loss of its function as a heat spreader. Furthermore, if the aluminum foil cracks, fine aluminum fragments may scatter from the cracks. Additionally, applying a load to the aluminum foil heater can cause the foil to deform and produce a metallic noise. This noise can cause problems depending on the application. For example, in the case of an aluminum foil heater used in a seat heater, the aluminum foil may break or scatter as described above due to the load from repeated sitting, or passengers may experience unpleasant noise when sitting down.

[0063] In contrast, since a black heat-bonded layer 4 is fused onto the aluminum-coated substrate 3 in the planar heater 10 of this embodiment, tearing and peeling of the aluminum film on the aluminum-coated substrate 3 are prevented. Furthermore, noise can be suppressed.

[0064] The leakage current during a malfunction when the surface heater 10 is used in a seat heater was investigated. When the surface heater 10 is used in a seat heater, repeated sitting pressure may cause the bare resistive wire 521 of the rope-shaped heating element 5 to break. Once the bare resistive wire 521 breaks, the resistance value of the broken portion increases, resulting in localized heating. This heat softens the polyurethane resin coating layer 522 and the insulating coating layer 53. Furthermore, once a break occurs, the bare resistive wire 521, constrained by twisting and / or winding stress, will break free from this stress and unravel. As a result, it is foreseeable that the broken end of the bare resistive wire 521 will protrude from the softened portion.

[0065] To address this issue, previous seat heaters using rope-shaped heating elements employed thicker insulation materials for the base and thicker leather or synthetic resin insulation for the outer layer to prevent contact between the rope-shaped heating element and the human body. Furthermore, the power supply voltage was a low 12V DC.

[0066] On the other hand, in the planar heater 10 of this embodiment, the rope-shaped heating element 5 is disposed on the aluminum-coated substrate 3 and the black heat-fusion layer 4. If the bare resistor wire 521 breaks, and the wire end directly contacts the aluminum-coated substrate 3, leakage will occur in the aluminum-coated substrate 3. To prevent this, a carbon-free insulating heat-fusion film, such as a polyolefin, instead of the black heat-fusion layer 4, can be fused to the surface of the aluminum-coated substrate 3. Furthermore, the carbon-free polyolefin insulating heat-fusion film can ensure insulation when the bare resistor wire 521 breaks and prevent the aluminum film of the aluminum-coated substrate 3 from tearing and peeling. However, the carbon-free polyolefin insulating heat-fusion film cannot achieve the energy-saving effect of far-infrared radiation.

[0067] In this embodiment, instead of the aforementioned insulating heat-fused film used to prevent leakage, a black heat-fused layer 4 containing carbon and having high impedance but not being an insulator is heat-fused to the surface of the aluminum-coated substrate 3. This embodiment emphasizes the energy-saving effect achieved by the far-infrared radiation function of the black heat-fused layer 4.

[0068] The leakage current flowing through the black thermally bonded layer 4 was investigated. Due to the high longitudinal resistance of the black thermally bonded layer 4, the leakage current is expected to be less than 1 μA, depending on the location, when in contact with DC12V. An example of a malfunction involving leakage current was investigated. It was assumed that a break occurred near the positive terminal of the rope-shaped heating element 5 connected to the DC12V power supply, and one end of the broken bare resistor wire 521 was perpendicularly in contact with the black thermally bonded layer 4, while the aluminum-coated substrate 3 was in contact with the negative terminal of the power supply. In this case, the diameter of the bare resistor wire 521 was set to 0.075 mm, the thickness of the black thermally bonded layer 4 was set to 0.15 mm, and the surface resistivity was set to 3 × 10⁻⁶. 8 Ω / cm 2 Due to the high surface resistivity, the leakage current does not diffuse laterally but flows almost entirely vertically. The resistance of the black thermally bonded layer 4, which is contacted by one of the thin bare resistive wires 521, is approximately 750 MΩ or higher, and the leakage current is expected to be below 0.02 μA. Even if all three bare resistive wires 521 break, the leakage current will be less than 1 μA. This value is considered negligible compared to the overall leakage current of the vehicle.

[0069] The commercially available carbon-pigment composite used as the raw material for the black hot-melt layer 4 is used as a material for antistatic and electromagnetic interference protection. Even when diluted with polyethylene resin, EVA resin, etc., this composite maintains its antistatic function, and the black hot-melt layer 4 containing this composite can act as an antistatic agent. Therefore, unlike carbon-free insulating hot-melt films, the carbon-containing black hot-melt layer 4, in addition to the aforementioned far-infrared radiation function, also possesses antistatic properties.

[0070] The surface heater of this embodiment can be used, for example, in automotive seat heaters. The aforementioned energy-saving function is also important in electric vehicle seat heaters, which have become increasingly popular in recent years. By suppressing power consumption, it is possible to reduce battery consumption in electric vehicles and extend the driving range per charge.

[0071] Furthermore, especially for autonomous driving using artificial intelligence, electric vehicles are equipped with a greater number of various low-voltage power supply electronic devices than ever before. In the car seats, synthetic resins such as polyurethane or polyester are used in the seat base, seat cover, and seat heaters disposed between them, making them prone to generating static electricity through friction. The high-voltage charged state associated with static electricity, or the noise caused by its high-voltage discharge, can affect electronic devices. In contrast, the antistatic function of the black heat-fused layer 4 included in the planar heater 10 of this embodiment effectively reduces noise that could affect electronic components.

[0072] Furthermore, the seat heater described above is not limited to automobile seats, but can also be used for seats in other vehicles, various facilities, and the like. Additionally, the aforementioned surface heater can also be used in various surface heating devices such as electric blankets and medical blankets.

[0073] [Joint-type surface heater]

[0074] The second embodiment relates to a joint-type planar heater. The differences between the second embodiment and the first embodiment are described, and identical parts are given the same reference numerals and their descriptions are omitted. Figure 2A This is a schematic top view showing an overview of the structure of the planar heater 20 in this embodiment. Figure 2B For along Figure 2A A schematic cross-sectional view of the planar heater 20 along the IIB-IIB line.

[0075] like Figure 2B As shown, the planar heater 20 of the second embodiment includes a heating wire holding substrate 21 having the same composition as the heating wire holding substrate 11 of the planar heater 10 of the first embodiment. A rope-shaped heating element 5 is fixed on the heating wire holding substrate 21 by bonding.

[0076] In the second embodiment, a heat-fusion layer 54 is provided on the rope-shaped heating element 5, which is the same as in the first embodiment, by means of extrusion molding or the like, to cover its outer periphery. The material of the heat-fusion layer 54 is preferably a polyolefin resin used in the black heat-fusion layer 4, and is carbon-free. The heat-fusion layer 54 can be, for example, polyethylene, polypropylene, polybutene, etc. Among them, low-density polyethylene, linear low-density polyethylene, etc. are particularly preferred from the perspectives of melting point, heat-fusion properties, and price. Since the heat-fusion layer 54 needs to ensure both the bonding strength between the black heat-fusion layer 4 and the rope-shaped heating element 5 and the gap, its thickness is relatively thick, and is usually preferably, for example, about 0.15 mm to 0.25 mm.

[0077] Furthermore, on the surface portion of the black heat-fusion layer 4 that is configured to cover the rope-shaped heating element 5 by the heat-fusion layer 54, a heat-fusion layer 8 identical to the heat-fusion layer 54 covering the rope-shaped heating element 5 can be provided. Alternatively, this heat-fusion layer 8 can also be formed by using the heat-fusion layer 54 covering the rope-shaped heating element 5 during heat fusion.

[0078] The rope-shaped heating element 5, covered by the black heat-fusion layer 4 and the heat-fusion layer 54, is fixed by heat fusion through methods such as hot pressing. At this time, the temperature, pressure, and time of the hot pressing are controlled to ensure a small gap between the rope-shaped heating element 5 and the heat-fusion layer 54. Through this gap, the slippage of the rope-shaped heating element 5 within the heat-fusion layer 54 absorbs the deformation of the planar heater 20 and the rope-shaped heating element 5 caused by external loads, achieving high durability.

[0079] Furthermore, as with the single insulated rope-shaped heating element 5 described above, the unevenness exposed on the surface due to twisting makes it difficult to uniformly ensure the minute gap between it and the heat-welded layer 54 as described above. Therefore, in this embodiment, it is preferable to use... Figure 1C The rope-shaped heating element 5 is covered by the insulating coating layer 53 shown.

[0080] The joint-type surface heater 20 of the second embodiment is also excellent in terms of safety, instantaneous heating, uniform heating and energy saving, just like the stitched surface heater 10 of the first embodiment, and can achieve the same effect.

[0081] [Covered surface heater]

[0082] The third embodiment relates to a covered planar heater. The differences between the third embodiment and the second embodiment are explained, and the same parts are given the same symbols and their descriptions are omitted. Figure 3A This is a schematic top view showing the general structure of the planar heater 30 in this embodiment. Figure 3B To indicate along Figure 3A A schematic cross-sectional view of the planar heater 30 along line IIIB-IIIB.

[0083] like Figure 3B As shown, similar to the heating wire holding substrate 21 of the bonding type surface heater 20 in the second embodiment, the surface heater 30 of the third embodiment includes a heating wire holding substrate 31 having an insulating substrate 1, an adhesive layer 2, and an aluminum-coated substrate 3. In the heating wire holding substrate 31 of this embodiment, a heat-fusion layer 7 is provided on the surface of the aluminum-coated substrate 3. The thickness of the heat-fusion layer 7 is the same as that of the black heat-fusion layer 4 of the heating wire holding substrate 21 of the bonding type surface heater 20 in the second embodiment. On the other hand, the material of the heat-fusion layer 7 is different from that of the black heat-fusion layer 4. The material of the heat-fusion layer 7 is the same as that of the heat-fusion layer 54 covering the rope-shaped heating element 5 in the second embodiment. The heat-fusion layer 7 can prevent the aluminum film of the aluminum-coated substrate 3 from peeling off and has the function of heat-fusion bonding the rope-shaped heating element 5 covered by the heat-fusion layer 54 to the aluminum-coated substrate 3.

[0084] In addition, similar to the case of the bonding type surface heater 20 in the second embodiment, a heat-fusion layer 8, the same as the heat-fusion layer 54, may be provided on the surface portion of the heat-fusion layer 7 on which the rope-shaped heating element 5 covered by the heat-fusion layer 54 is disposed.

[0085] The rope-shaped heating element 5, which is covered by an aluminum-coated substrate 3, a heat-fusion layer 7, and a heat-fusion layer 54, is fixed by heat fusion through methods such as hot pressing. During heat fusion fixing, the temperature, pressure, and time of the hot pressing are controlled to ensure a small gap between the rope-shaped heating element 5 and the heat-fusion layer 54. Utilizing this gap, the slippage of the rope-shaped heating element 5 within the heat-fusion layer 54 absorbs the deformation of the planar heater 30 and the rope-shaped heating element 5 caused by external loads, achieving high durability.

[0086] In the planar heater 30 of this embodiment, not only is the heating wire holding substrate 31 and the rope-shaped heating element 5 thermally fused together, but also a black thermally fused layer 4, the same as in the first and second embodiments, is provided to cover the entire surface of the planar heater 30. The black thermally fused layer 4 is thermally fused together and fixed by hot pressing or the like to form a covered planar heater 30.

[0087] The covering surface heater 30 of the third embodiment is similar to the stitching surface heater 10 of the first embodiment and the joining surface heater 20 of the second embodiment, and has excellent safety, instant heating, uniform heating and energy saving, and can achieve the same effect.

[0088] Example

[0089] Examples of the planar heaters described in the three embodiments above will be explained.

[0090] [sample]

[0091] <General Section>

[0092] In any embodiment, the insulating substrate 1 uses a material with a density of approximately 40 kg / m³ that meets the MVSS302 flame retardant standard. 2 The insulation substrate 1 is a semi-rigid polyurethane foam with a hardness of 98N or higher. The thickness of the insulation substrate 1 is 3.5mm. The aluminum-coated substrate 3 uses a commercially available plain-woven cotton fabric with a single-sided aluminum vapor-deposited coating, typically used as an ironing cover. The adhesive used to bond the insulation substrate 1 and the aluminum-coated substrate 3 to form the adhesive layer 2 is a neoprene solvent-based adhesive GS1Z (manufactured by Konishi Corporation). This adhesive is sprayed onto the insulation substrate 1 and air-dried, then the aluminum-coated substrate 3 is placed on top, and the adhesive is cured by hot pressing at 60°C for 5 minutes.

[0093] The black hot-melt layer 4 was prepared as described below. The main material used for the black hot-melt layer 4 was a commercially available pigment compound (manufactured by Tokyo Ink Co., Ltd.) under the trade name "Papiostat PST5011". This pigment compound is a substance obtained by dispersing carbon black in low-density polyethylene. In addition to this pigment compound, low-density polyethylene resin (LDPE) L1640 (manufactured by Asahi Kasei Corporation), ethylene-vinyl acetate copolymer (EVA) NUC3830 (manufactured by ENEOS NUC Co., Ltd.), and general antioxidants and flame retardants were added to form the formulation shown in Table 1. These mixtures were thoroughly stirred in a mixer, and then a black hot-melt layer 4 with a thickness of 0.15 mm was produced using a biaxial stretching film manufacturing apparatus consisting of a short-shaft extruder. Here, the average surface resistivity of formulation 1 is approximately 10 Ω·cm. 8 Ω / cm 2 The average surface resistance of formulation 2 is approximately 10. 6 Ω / cm 2 .

[0094] [Table 1]

[0095] Table 1. Formula Table (Unit: servings)

[0096]

[0097] The rope-shaped heating element 5 is described below. The core 51 is made of a fully aromatic polyester fiber (manufactured by Kuraray Corporation) of trade name "Vectran HT" 560dtex / 100f bundled into a product with an outer diameter of 0.25mm. The bare resistance wire 521 uses a copper-tin alloy wire with a diameter of φ0.075mm. Three bare resistance wires 521 are twisted together, and polyurethane is coated on their surface to form a coating layer 522, thus forming a stranded wire 52. Six stranded wires 52 are aligned and wound horizontally around the core 51 at a spacing of 1.815mm. On top of this, ETFE resin is extruded and coated with an insulating coating layer 53 with a thickness of 0.2mm, thus forming a rope-shaped heating element 5 with an outer diameter of 0.9mm. In all examples 1 to 5 and Comparative Examples 1 and 2 described later, the wiring length of this rope-shaped heating element 5 is 5.75±0.06m, and the resistance value is 1.9±0.02Ω.

[0098] <Example 1>

[0099] As Example 1, a mixture was prepared. Figure 1B The stitch-type surface heater 10 of the first embodiment shown was tested. The stitch-type surface heater 10 was prepared as described below.

[0100] The black heat-fused layer 4, based on formulation 1 in Table 1, was disposed on the pre-bonded insulating substrate 1 and aluminum-coated substrate 3. These integral parts were extruded and heated using a hot press to heat-fuse the aluminum-coated substrate 3 and the black heat-fused layer 4. The heating temperature was set to 180°C, and the heating time was set to 20 seconds. The resulting planar body was used as the heating wire holding substrate 11. On the surface of the heating wire holding substrate 11, an automatic thread sewing machine controlled by a program was used to thread the rope-shaped heating element 5 according to a predetermined pattern, while simultaneously sewing it into a zigzag shape using upper thread 6a and lower thread 6b. As described above, the planar heater 10 of Example 1 was manufactured.

[0101] <Example 2>

[0102] As Example 2, a mixture was prepared. Figure 1B The stitched surface heater 10 of the first embodiment shown was tested. The only difference between Example 2 and Example 1 is that the formula of the black heat-fusion layer 4 is replaced by formula 2 of Table 1 instead of formula 1 of Table 1.

[0103] <Example 3>

[0104] As an example 3, a mixture was prepared. Figure 2B The second embodiment of the bonding-type planar heater 20 was shown and tested. The bonding-type planar heater 20 was prepared as described below.

[0105] A heat-welded layer 54 was formed on the surface of the rope-shaped heating element 5 using a general-purpose extruder. Low-density polyethylene resin (LDPE) L1640 (manufactured by Asahi Kasei Corporation) was used in the heat-welded layer 54. The thickness of the heat-welded layer 54 was set to 0.2 mm. The heat-welded layer 54 was extruded into a tubular shape, creating only a tiny gap between it and the rope-shaped heating element 5.

[0106] The wiring utilizes a wiring platform with spring pins embedded along the wiring pattern. The rope-shaped heating element 5, covered by the heat-fusion layer 54, is hooked onto the spring pin of the wiring platform for wiring. Above this, a heating wire holding substrate 21, identical to the heating wire holding substrate 11 of Example 1, is arranged with the black heat-fusion layer 4 as the lower side. The entire assembly is pressed and heated using a hot press, heat-fusion bonding the heat-fusion layer 54 of the rope-shaped heating element 5 to the black heat-fusion layer 4 of the heating wire holding substrate 21. The heating temperature is set to 180°C, and the heating time is set to 10 seconds. This produces the planar heater 20 of Example 3.

[0107] <Example 4>

[0108] As an example 4, a mixture was prepared. Figure 2BThe second embodiment of the bonding-type planar heater 20 was shown and tested. The only difference between Example 4 and Example 3 is that the thickness of the black heat-fusion layer 4 is set to 0.35 mm.

[0109] <Example 5>

[0110] As Example 5, a mixture was prepared. Figure 3B The covered surface heater 30 of the third embodiment shown was tested. The covered surface heater 30 was manufactured as follows.

[0111] A heat-fusion layer 7, composed of a 0.15 mm thick transparent low-density polyethylene film, is disposed on top of the pre-bonded insulating substrate 1 and aluminum-coated substrate 3. These components are pressed and heated using a hot press to heat-fuse the aluminum-coated substrate 3 and the heat-fusion layer 7. The heating temperature is set to 180°C, and the heating time is set to 20 seconds. This integrated planar body is used as the heating wire holding substrate 31.

[0112] Similar to Example 3, a rope-shaped heating element 5 covered by a heat-fusion layer 54 was fabricated. Also similar to Example 3, the rope-shaped heating element 5 covered by the heat-fusion layer 54 was hooked onto a spring pin on a wiring table for wiring. A heating wire holding substrate 31 was then positioned with the heat-fusion layer 7 as the underside. The entire assembly was pressed and heated using a hot press, heat-fusion bonding the heat-fusion layer 54 of the rope-shaped heating element 5 to the heat-fusion layer 7 of the heating wire holding substrate 31, thus creating an intermediate product. The heating temperature was set to 180°C, and the heating time was set to 10 seconds.

[0113] Next, a black heat-fusion layer 4 is applied to the entire surface of the intermediate product. The entire product is then pressed and heated using a hot press, thereby heat-fusion bonding the heat-fusion layer 7, the rope-shaped heating element 5, and the black heat-fusion layer 4. The heating temperature is set to 180°C, and the heating time is set to 20 seconds. This produces the planar heater 30 of Example 5.

[0114] <Comparative Example 1>

[0115] As Comparative Example 1, a surface heater was prepared in which a rope-like heating element 5 was wired on an insulating substrate 1 and stitched together with an upper wire 6a and a lower wire 6b. This surface heater is equivalent to the product of the stitched surface heater 10 of the first embodiment, which lacks the adhesive layer 2, the aluminum coated substrate 3, and the black heat-fusion layer 4. Comparative Example 1 is a product whose structure is conventionally known as a surface heater for use in seat heaters.

[0116] <Comparative Example 2>

[0117] As Comparative Example 2, a planar heater was prepared by wiring a rope-like heater 5 on a heating wire holding substrate having an insulating substrate 1, an adhesive layer 2, and an aluminum-coated substrate 3, and simultaneously stitching it together with an upper wire 6a and a lower wire 6b. This planar heater is equivalent to the product without the black heat-fusion layer 4 in the stitched planar heater 10 of the first embodiment. Comparative Example 2 is a product having a structure obtained by adding an aluminum-coated substrate 3 to a conventionally known planar heater.

[0118] <Comparison of Contents of Examples and Comparative Examples>

[0119] The combinations of elements and conditions constituting Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 2.

[0120] [Table 2]

[0121] Table 2: Combinations of individual elements in each embodiment and comparative example

[0122]

[0123] [Methods for measuring the performance of planar heaters]

[0124] Samples of the planar heaters from Examples 1-5 and Comparative Examples 1 and 2 were placed on insulated / elastic seats of automobiles, and the temperature performance of the planar heater surface was measured directly without covering the seat cover. Measurements were conducted in a windless environment at room temperature (25°C). A 50×50mm, 1mm thick copper heat collector plate with a thermocouple attached was used in the center of the measurement. This heat collector plate was placed in the center of the planar heater and sealed to the planar heater with a weight of 1 kg, separated by an insulating material larger than the copper heat collector plate. The thermocouple was connected to a general-purpose temperature recorder, recording temperature changes every second.

[0125] Furthermore, a temperature control thermocouple is attached to the surface of a planar heater, which is positioned corresponding to the measuring thermocouple at the center of the aforementioned copper heat collector plate. The temperature control thermocouple is configured to not contact the rope-shaped heating element 5. The temperature control thermocouple is connected to a temperature controller. Additionally, since the impedance of the rope-shaped heating element 5 is temperature-dependent, for each sample, the applied voltage (approximately 12.5V) is fine-tuned beforehand while observing the power meter to ensure a power consumption of 82.1W at 40°C.

[0126] <Rise Time>

[0127] The surface heater was directly connected to a DC power supply without a temperature regulator. The power switch was turned on, and the temperature rise was recorded using a temperature recorder. Based on the records, the time it took for the surface temperature of the surface heater to reach 40°C and 50°C, respectively, was measured.

[0128] <Overshoot Temperature>

[0129] The surface heater is connected to a DC power supply via a temperature controller. The temperature controller is set to cut off the power supply when the temperature measured by the temperature control thermocouple reaches 40°C. When the power switch is turned on, the temperature rise is recorded using a temperature recorder. Based on the record, the highest temperature of the earliest overshoot exceeding 40°C is measured, and the difference between this and 40°C is determined as the overshoot temperature.

[0130] <Power Consumption>

[0131] The surface heater was connected to a DC power supply via an ON-OFF type temperature controller. With the switch turned ON, the automatic temperature control mode was activated, and power consumption was measured. The OFF setting temperature of the temperature controller was set to 40°C, the ON setting temperature to 39.5°C, and the hysteresis width to 0.5°C. Power consumption was measured using a cumulative energy meter. The measurement period was set to 30 minutes from the moment the power switch was turned ON. The average cumulative energy consumption was determined as the average power consumption.

[0132] Far-infrared heating

[0133] A single planar heater was suspended in the air at 25°C in a windless environment and connected to a DC power supply via a temperature controller. The temperature controller was set to 40°C and configured for automatic temperature control. A large black cloth, large enough to conceal the heater, was spread out 15 cm above the heater's surface. The temperature of the cloth surface corresponding to the center of the heater was measured using a far-infrared thermal imager. Measurements were taken at 1-minute intervals for 10 minutes, and the average temperature was determined as the far-infrared heating temperature.

[0134] <Seating Pressure>

[0135] A surface heater was configured to be sandwiched between the insulated / elastic seat and the cover of a car, and a test subject was prepared by applying DC 13.5V to the surface heater. Using a humanoid robot, rotation / sliding of the seat for boarding and sitting was performed, followed by a 40 kg load and 20 up-and-down vibrations, and then the reverse motion for getting out of the seat was performed, which constituted one cycle. A life test was conducted by repeating this cycle 10,000 times. After this test, a visual inspection was performed to check for any tiny aluminum flakes that might have been generated due to damage to the aluminum coating substrate 3 and flew out from the black heat-welded layer 4 or the polyethylene heat-welded layer 7. In addition, a visual inspection was performed to check for any carbon-containing tiny flakes that might have been generated due to damage to the black heat-welded layer 4.

[0136] Antistatic

[0137] The surface heater is sandwiched between the car's insulated / elastic seat and the cover. A DC power supply is connected to the surface heater, but it is set to an OFF state. After rubbing the surface of the cover with a piece of polyester cloth approximately 30cm square 10 times, the voltage at a distance of 25mm is immediately measured using an electrostatic tester.

[0138] [Measurement Results of the Performance of the Planar Heater]

[0139] The results of the above measurements are shown in Table 3.

[0140] [Table 3]

[0141] Table 3: Experimental Results

[0142] project unit Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 40℃ rise time (Second) 120 117 116 138 125 280 112 50℃ rise time (Second) 315 318 311 377 322 569 303 Overshoot temperature (℃) 1.7 1.6 1.3 2.4 1.9 5.7 1.1 Average power consumption (W) 36.8 37.1 36.2 39.9 38.2 43.5 35.6 Far-infrared heating (℃) 28.4 28.9 29.1 30.6 29.8 26.1 26.9 Seating test No abnormalities No abnormalities No abnormalities No abnormalities No abnormalities ** crack With voltage (KV) 2.8 1.7 2.5 2.5 2.0 5.8 3.4

[0143] <Evaluation of the time of ascent>

[0144] Examples 1-5 have thermodynamically similar structures with an aluminum-coated substrate 3, and the difference in rise time between them is very small. Compared with the 40°C rise time of Comparative Example 1, which has no aluminum-coated substrate 3 and only an insulating substrate 1 for holding the heating wire, Examples 1-5 have more than twice the instantaneous heating performance. Furthermore, Comparative Example 2, which has an insulating substrate 1, an adhesive layer 2, and an aluminum-coated substrate 3 for holding the heating wire, also exhibits the same significant instantaneous heating performance as Examples 1-5. This confirms that the aluminum-coated substrate 3 has a greater effect on instantaneous heating performance.

[0145] It was found that even when comparing the 50°C rise time of Examples 1-5 with Comparative Example 1, Examples 1-5 exhibited nearly twice the instantaneous heating performance. However, when comparing Comparative Example 2 (without the black heat-fusion layer 4), Examples 3 and 4 (with different thicknesses of the black heat-fusion layer 4), it was found that Example 4, with a thicker black heat-fusion layer 4, had slightly worse instantaneous heating performance. It is understood that the black heat-fusion layer 4 should not be too thick; for example, the black heat-fusion layer 4 is preferably less than 0.35 mm.

[0146] Therefore, by setting an aluminum-coated substrate 3 on the heating wire holding substrate, the rise time can be advanced, thus achieving energy saving for the surface heater.

[0147] <Evaluation of overshoot>

[0148] In Examples 1-5, which have thermodynamically similar structures, the overshoot temperatures did not differ significantly. However, comparing the overshoot temperatures of Examples 1-5 with Comparative Example 1 reveals that the overshoot temperatures of Examples 1-5 are as small as 1 / 2 to 1 / 4 of the overshoot temperature of Comparative Example 1. Comparing the overshoot temperatures of Comparative Example 2, which has an aluminum-coated substrate 3 for holding the heating wire, with Comparative Example 1 shows that the overshoot temperature of Comparative Example 2 is extremely small, only 1 / 5 of the overshoot temperature of Comparative Example 1. These results clearly indicate that the reduction in overshoot is due to the rapid thermal response of the aluminum-coated substrate 3.

[0149] Comparing Comparative Example 2 (without the black heat-fusion layer 4) with Examples 3 and 4 (with different thicknesses of the black heat-fusion layer 4), it can be seen that in Example 4, where the black heat-fusion layer 4 is thicker, the overshoot temperature is slightly higher. This indicates that the black heat-fusion layer 4 should not be too thick; for example, the black heat-fusion layer 4 is preferably less than 0.35 mm.

[0150] This confirms that by providing an aluminum-coated substrate 3 on the heating wire holding substrate, a rapid thermal response can be obtained, resulting in energy savings for the planar heater.

[0151] <Evaluation of Average Power Consumption>

[0152] In Examples 1-5, the average power consumption was controlled at a lower value compared to Comparative Example 1. In particular, in Examples 1-3, power savings of more than 15% were achieved compared to Comparative Example 1. The inventors believe that the average power consumption of Example 5 is slightly higher than that of Examples 1-3 because the outermost layer of the planar heater is covered by the black heat-fusion layer 4, resulting in good heat preservation and a slightly slower thermal response. This can be understood as the relatively low average power consumption of Comparative Example 2, where the aluminum-coated substrate 3 is exposed, indicating good heat dissipation and a fast thermal response. By comparing Examples 3 and 4 with different thicknesses of the black heat-fusion layer 4, it can be seen that the average power consumption is slightly higher in Example 4, where the black heat-fusion layer 4 is relatively thicker. This indicates that the black heat-fusion layer 4 should not be too thick; for example, the black heat-fusion layer 4 is preferably less than 0.35 mm. It can be seen that the planar heater of the present invention can achieve power savings.

[0153] <Evaluation of Far-Infrared Radiation>

[0154] In Examples 1-5, which relate to the planar heater with the black heat-fusion layer 4, a temperature rise of approximately 3.5°C to 5°C was observed on the surface of the measuring black cloth. This temperature rise includes the temperature rise caused by far-infrared radiation. In contrast, in Comparative Examples 1 and 2, which relate to the planar heater without the black heat-fusion layer 4, the temperature rise on the surface of the measuring black cloth was very small. In Example 4, where the black heat-fusion layer 4 is thicker, and in Example 5, where the black heat-fusion layer 4 is the outermost layer, the surface temperature of the measuring black cloth was slightly higher compared to Examples 1-3.

[0155] Furthermore, in this embodiment, the temperature was measured at a distance of 15 cm from the surface heater. In contrast, when the surface heater is used as a seat heater, it is in close contact with the human body. In this case, the far-infrared radiation provides a greater feeling of warmth than in the embodiment of this invention.

[0156] The black heat-fusion layer 4 exhibits a low component of thermal radiation unsuitable for human heating and a high component of far-infrared radiation effective for human heating in its heat generation energy. Therefore, the planar heater of this embodiment can achieve energy-saving effects through far-infrared radiation.

[0157] <Evaluation of Seating Pressure>

[0158] In Comparative Example 2, where the surface of the aluminum-coated substrate 3 was not protected by the black heat-fusion layer 4 and / or heat-fusion layer 7, multiple instances of aluminum film peeling, scattering of tiny aluminum flakes, and exposure of cotton fabric were observed. In contrast, in Examples 1-5, since the aluminum-coated substrate 3 was covered by the black heat-fusion layer 4 or heat-fusion layer 7, tiny aluminum flakes did not appear due to damage to the covering layer.

[0159] In addition, in Examples 1 to 5, although wrinkles were generated in the black heat-fused layer 4 and heat-fused layer 7 after testing, the black heat-fused layer 4 and heat-fused layer 7 were not damaged, and no tiny carbon flakes were found to scatter.

[0160] Thus, it can be seen that the article obtained by thermally fusing the aluminum-coated substrate 3 with the black hot-melt layer 4 or the hot-melt layer 7 is sufficient to protect the aluminum coating film. That is, it can be confirmed that the planar heater of the embodiment of the present invention can provide high safety.

[0161] <Related evaluation of antistatic properties>

[0162] The surface heater of Comparative Example 1, which lacks the aluminum-coated substrate 3 and the black heat-fused layer 4, exhibited a higher measured voltage. In contrast, the surface heaters of Examples 1-5 had measured voltages controlled to be less than half that of Comparative Example 1. That is, it was determined that the black heat-fused layer 4 is an antistatic material.

[0163] Furthermore, in Examples 1-5, the voltage was lower in Example 2, where the carbon concentration was relatively high. This is believed to be because the static electricity carried in the planar heater of Example 2 was rapidly consumed by the black heat-fused layer 4, which has an appropriate resistance value.

[0164] Compared to the surface heater of Comparative Example 2, which lacks the black heat-fusion layer 4, the surface heaters of Examples 1-5 exhibit lower resistance values ​​and superior circuit performance due to the lower resistance of the aluminum-coated substrate 3. However, since the surface heater of Comparative Example 2 lacks the black heat-fusion layer 4, it is significantly inferior to the surface heaters of Examples 1-5, which have the black heat-fusion layer 4, in terms of energy consumption due to electrostatic resistance.

[0165] Therefore, it can be seen that the high impedance of the black heat-fusion layer 4 serves as an anti-static agent. This indicates that the planar heater with the black heat-fusion layer 4 can reduce various noises caused by static electricity compared to the case without the black heat-fusion layer 4.

[0166] As described above, in the planar heater of the present invention, the combined structure of the aluminum-coated substrate 3 and the black heat-fusion layer 4 achieves the following effects. Structurally, the planar heater of this embodiment can utilize the rope-shaped heating element 5, which has historically ensured reliability. Furthermore, in terms of performance, the planar heater of this embodiment exhibits rapid heating, minimal overshoot, suitability for human body heating using far-infrared radiation, low power consumption, strong resistance to sitting pressure, anti-static properties, high design flexibility, excellent cost-effectiveness, and energy efficiency.

[0167] The present invention has been described above with reference to preferred embodiments. It is self-evident that the present invention is not limited to the above embodiments, and various modifications and implementations can be made within the scope of the present invention.

Claims

1. A surface heater, comprising: a heat-insulating base material; a bonding agent layer provided on the heat-insulating base material; a metal-coated base material provided on the bonding agent layer; a first heat-fusion layer provided on a surface of the metal-coated base material; a string-shaped heat generator; and a black heat-fusion layer provided so as to cover the metal-coated base material and the string-shaped heat generator, the first heat-fusion layer being provided between the metal-coated base material and the string-shaped heat generator, the string-shaped heat generator being covered with a second heat-fusion layer, the first heat-fusion layer heat-fusing the string-shaped heat generator covered with the second heat-fusion layer to the metal-coated base material.

2. The surface heater according to claim 1, wherein the metal-coated base material, the first heat-fusion layer, the string-shaped heat generator covered with the second heat-fusion layer, and the black heat-fusion layer are fixed by heat fusion.

3. A surface heater, comprising: a heat-insulating base material; a bonding agent layer provided on the heat-insulating base material; a metal-coated base material provided on the bonding agent layer; a black heat-fusion layer provided on the metal-coated base material; and a string-shaped heat generator provided on the black heat-fusion layer, the heat-insulating base material, the bonding agent layer, the metal-coated base material, and the black heat-fusion layer being arranged in the order of the heat-insulating base material, the bonding agent layer, the metal-coated base material, and the black heat-fusion layer in a portion where the string-shaped heat generator is not arranged, the black heat-fusion layer containing carbon particles, a polyolefin resin, and a polyolefin-based copolymer.

4. The surface heater according to claim 3, wherein the polyolefin resin is polyethylene, and the polyolefin-based copolymer is an ethylene-vinyl acetate copolymer.

5. The surface heater according to claim 3, wherein the black heat-fusion layer is provided between the metal-coated base material and the string-shaped heat generator.

6. The surface heater according to claim 5, wherein the black heat-fusion layer is heat-fused to the metal-coated base material, and the string-shaped heat generator arranged on the black heat-fusion layer is stitched to a heating wire holding base material containing the heat-insulating base material, the metal-coated base material, and the black heat-fusion layer.

7. The surface heater according to claim 5, further comprising a heat-fusion layer provided on an outer periphery of the string-shaped heat generator, the metal-coated base material, the black heat-fusion layer, and the string-shaped heat generator provided with the heat-fusion layer being fixed by heat fusion.

8. The surface heater according to any one of claims 1 to 7, wherein the black heat-fusion layer is provided on the metal-coated base material.

9. The surface heater according to any one of claims 1 to 7, wherein the black heat-fusion layer is an antistatic body.

10. The surface heater according to any one of claims 1 to 7, wherein the metal-coated base material is a woven fabric or a nonwoven fabric in which a surface is coated with aluminum, or a woven fabric formed of long fibers coated with aluminum.

11. The surface heater according to claim 10, wherein the aluminum coated on the surface has a thickness of 5 μm to 50 μm. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The thickness of the black heat fusion layer is 0.05mm~0.35mm, and the surface resistance is 10 5 Ω / cm 2 ~10 10 Ω / cm 2 . ​ ​ ​ ​ ​ ​ 12. The planar heater according to any one of claims 1 to 7, wherein The thermal insulation base material and the metal-coated base material are integrally formed by a nonwoven fabric coated with a metal on a surface.

13. A seat heater, wherein The planar heater according to any one of claims 1 to 7 is provided.

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