JP7353090B2 - Heat generating sheet for decorative parts and manufacturing method thereof - Google Patents

Description

The present invention relates to a heat-generating sheet for decorative parts, and more particularly to a heat-generating sheet with a snow-melting function that is provided on the surface of a decorative part of a vehicle.

Millimeter wave radar devices are installed in many vehicles in recent years because they can measure distances between vehicles and obstacles using millimeter waves. In order to detect a preceding vehicle, this millimeter wave radar device is usually mounted on the front of the vehicle, for example, in the center, avoiding the headlights and bumper. In many cases, a vehicle decorative part such as a front grill or an emblem is installed in the center, so millimeter wave radar devices are often installed inside or on the back side of the vehicle decorative part.

Vehicles equipped with millimeter-wave radar devices, especially in snowy regions, are controlled to temporarily stop measurement when snow accumulates in order to prevent snow from accumulating on vehicle decorative parts and causing malfunctions. However, the measurement temporary stop control makes it impossible to measure during snowfall. Therefore, there was a need to be able to perform measurements even during snowfall.

Patent Document 1 discloses a structural form in which nichrome wires as an example of a heating means are embedded in both sides of each water flow groove provided in a vehicle decorative part, and the nichrome wires melt adhering snow and drain it efficiently. is proposed. Additionally, Patent Document 2 proposes a technique for avoiding the formation of snow and ice layers by electrically heating a radar dome. Specifically, the heating of the radar dome is carried out through a deposited and decorated metal layer, which has an ohmic resistance and generates heat when a current is conducted in the lateral direction, thus reducing the electrical It acts as a heater.

Patent Document 3 proposes a vehicle decorative component that can melt snow attached to the vehicle decorative component by generating heat in a heater section, and prevents attenuation of millimeter waves when transmitted through the heater section. . This vehicle decorative part (emblem) includes a decoration main body and a heater part. The decoration main body is attached to the front in the direction of transmission of millimeter waves from the millimeter wave radar device, decorates the vehicle, and has millimeter wave transparency. The heater section includes a heating element that generates heat when energized. At least a portion of the heating element is disposed within the millimeter wave irradiation area in the heater section. As a millimeter-wave attenuation suppression mode that suppresses attenuation when millimeter waves pass through the heater part, the heating element is configured so that the attenuation amount of millimeter waves is an allowable value, which is the area ratio of the heating element to the same irradiation area within the irradiation area. It is installed in the heater section with the following settings.

JP2004-138572A (Paragraph 0020,0021) Japanese Patent Application Publication No. 2002-22821 Japanese Patent Application Publication No. 2018-66705

In Patent Document 3, the heater section is provided on the rear surface of the decorative main body so as not to interfere with the decorative form of the vehicle decorative part (emblem). However, this has the disadvantage that when transmitting heat to the surface of the decorative parts to melt snow, the heat must pass through the main body of the decoration, which reduces heat conduction efficiency and makes it impossible to melt snow quickly. .

The present invention has been made to solve the above-mentioned problems, and the object is to generate a heat generating device for decorative parts that can easily melt snow, etc. attached to the decorative parts without damaging the appearance of the decorative parts. The purpose is to provide seats.

The heat-generating sheet for decorative parts according to the present invention is a heat-generating sheet that is attached to the front surface of a decorative part for a vehicle in the transmission direction of millimeter waves transmitted from a millimeter-wave radar device, and is wire-drawn and has a diameter of 0. 0.015 to 0.15 mm, and at least two resin sheets sandwiching the heating wire, and the distance from the surface of the heating wire to the surface of the heating sheet is 0.025 to 0.02 mm. The diameter of the heating wire is within a range of 1/20 or more and 1/2 or less of the thickness of the heating sheet.

According to this invention, (a) since it is provided on the surface of the decorative component, the heat generated from the heat generating sheet does not need to pass through the decorative component, the heat conduction efficiency is good, and snow etc. adhering to the decorative component can be easily removed. It can be melted. As a result, snow melting can be carried out quickly while saving energy. (b) Also, since the heating wire is within the diameter range mentioned above, even if it is provided on the surface of a decorative part, it is not as easily visible compared to the case of a rectangular wire, and the appearance as a decorative part is without damaging it. (C) Furthermore, since the distance from the surface of the heating wire to the surface of the heating sheet is within the above range, insulation can be ensured and heat can be efficiently transmitted to the surface of the decorative component. (d) Since the diameter of the heating wire is defined in relation to the thickness of the heating sheet, it is preferable if the diameter of the heating wire is as small as about 1/20 of the thickness of the heating sheet because it can improve insulation. It is preferable that the diameter of the heating wire is as large as about 1/2 of the thickness of the heating sheet, since heat can be easily transferred to the surface of the heating sheet.

In the heat generating sheet for decorative parts according to the present invention, the two resin sheets sandwiching the heat generating line have the same or substantially the same thickness. According to this invention, since the heating wire is provided at the center or substantially the center of the heating sheet, the insulation on the front and back sides of the heating sheet can be made to be the same level, and stable insulation can be ensured.

In the heating sheet for decorative parts according to the present invention, the heating wire is a copper wire, a copper alloy wire, a plated copper wire, or a plated copper alloy wire with an electrical conductivity within the range of 3.5 to 100% IACS. According to this invention, it is possible to generate heat with less electric power, so that the heat generating sheet can be heated while saving energy.

In the heating sheet for decorative parts according to the present invention, it is preferable that the projected area ratio of the heating line in the portion through which the millimeter wave passes is within the range of 0.2 to 5.0%. According to this invention, in the heat generating sheet, the projected area ratio of the heat generating lines in the portion through which millimeter waves pass is within the above range, so that the appearance of the decorative component is not impaired as long as measurements are not affected.

According to the present invention, it is possible to provide a heat generating sheet for decorative parts that can easily melt snow and the like adhering to decorative parts without damaging the appearance of the decorative parts.

FIG. 1 is a cross-sectional view showing an example of a heat generating sheet for decorative parts according to the present invention. FIG. 2 is an explanatory diagram of the dimensional structure of the heat generating sheet for decorative parts according to the present invention. FIG. 2 is a plan view showing an example of the wiring pattern of the heat generating sheet for decorative parts according to the present invention. FIG. 7 is a plan view showing another example of the wiring pattern of the heat generating sheet for decorative parts according to the present invention. It is an explanatory view showing an example of use of the heat generating sheet for decorative parts according to the present invention.

A heat generating sheet for decorative parts according to the present invention will be explained with reference to the drawings. The present invention is not limited to the embodiments described below.

[Heating sheet for decorative parts]
As shown in FIGS. 1 to 5, the heat generating sheet 10 for decorative parts according to the present invention is attached to the front surface F of the decorative part 20 for a vehicle in the transmission direction of the millimeter waves 22 transmitted from the millimeter wave radar device 21. This is a heat generating sheet 10. The heat generating sheet 10 includes a drawn heat generating wire 1 having a diameter d within the range of 0.015 to 0.15 mm, and at least two resin sheets 2 sandwiching the heat generating wire 1. The distance D from the surface of the wire 1 to the surface of the heat generating sheet 10 is within the range of 0.025 to 0.4925 mm, and the diameter d of the heat generating wire 1 is 1/20 or more and 1/2 or less of the thickness of the heat generating sheet 10. It is characteristic that it is within the range of .

Since the heat generating sheet 10 is (a) provided on the surface F of the decorative component 20, the heat emitted from the heat generating sheet 10 does not need to pass through the decorative component 20, has good heat conduction efficiency, and does not adhere to the decorative component 20. Can easily melt snow, etc. As a result, snow melting can be carried out quickly while saving energy. (a) Also, since the exothermic wire 1 is within the range of the wire-drawn diameter d, even if it is provided on the surface of the decorative component 20, it cannot be easily recognized compared to the case of a rectangular wire, and the decorative component The appearance as 20 is not impaired. (c) Also, since the distance D from the surface of the heating wire 1 to the surface of the heating sheet 10 is within the above range, insulation can be ensured and heat can be efficiently transmitted to the surface of the decorative component 20. I can do it. (D) Since the diameter d of the heating wire 1 is within the range of 1/20 or more and 1/2 or less of the thickness of the heating sheet 10, it is possible to improve insulation and facilitate heat transfer. . (e) It is preferable that the projected area ratio of the heat generating line 1 in the portion through which the millimeter waves 22 pass is within the range of 0.2 to 5.0%, and the portion in the heat generating sheet 10 through which the millimeter waves 22 pass. Since the projected area ratio of the heating wire 1 is within the above range, the appearance of the decorative component 20 is not impaired as long as measurement is not affected.

The constituent elements will be explained in detail below. FIG. 2 is an explanatory diagram of the dimensions of each component, and the dimension codes shown in FIG. 2 will be used in the following description.

(heating wire)
The heating wire 1 is a heating element that generates heat when energized, and as the heating wire 1 for a heating sheet for decorative parts, the wire drawing diameter d is preferably within the range of 0.015 to 0.15 mm. . Since the heating wire 1 is within the above-mentioned wire-drawn diameter range, even if it is provided on the surface of the decorative component 20, it cannot be easily recognized compared to the case of a rectangular wire, which impairs the appearance of the decorative component 20. Never. If the diameter d of the heating wire 1 is less than 0.015 mm, it may be too thin and the strength may be poor, although it depends on the material of the heating wire 1. If the wire diameter of the heating wire 1 exceeds 0.15 mm, the wire may be too thick and stand out, degrading the appearance of the decorative component 20. In this application, the diameter d of the heating wire 1 refers to the diameter of the metal wire, not the diameter after the insulation coating or the fusion coating is provided.

Examples of the material of the heating wire 1 include copper wire, copper alloy wire, plated copper wire, and plated copper alloy wire. Since the heating wire 1 made of these materials has an electrical conductivity within the range of 3.5 to 100% IACS, it can generate heat with a small amount of electric power, and the heating sheet can be heated while saving energy. Examples of the copper alloy wire include copper wire, silver-containing copper alloy wire, tin-containing copper alloy wire, and nickel-containing copper alloy wire. Among them, silver-containing copper alloy wire containing 4 to 10% by mass of silver, tin-containing copper alloy wire containing 0.1 to 1.5% by mass of tin, and nickel-containing copper containing 0.5 to 50% by mass of nickel. Preferably, alloy wires are used.

Preferred types of plating in the case of plating include silver plating, tin plating, and nickel plating. It is preferable that whether or not to provide plating is arbitrarily selected depending on the end treatment means of the heating wire 1. For example, when connecting the heating wire 1 to an electrode, a terminal, etc. using an ultrasonic welder, it is preferable that no plating be provided. When connecting by soldering, it is preferable to apply plating with nickel, solder, tin, silver, etc. to prevent copper from oxidizing during soldering.

The heating wire 1 has different volume resistivity, tensile strength, etc. depending on its material. Therefore, it can be selected according to the characteristics of the heating wire 1. Among the heating wires 1 described above, the copper alloy wire containing 10% by mass of silver used in the examples described later has a volume resistivity of 0.023 μΩcm and a tensile strength (Young's modulus) of 11000 N/mm ² . A copper alloy wire such as a copper alloy wire has a good balance between volume resistivity and tensile strength, and can be said to be preferable as a constituent material of the heat generating sheet 10 provided on the surface of a decorative part for a vehicle.

The heating wire 1 may be composed of a bare wire itself after wire drawing, or may have a single-layer or multi-layer insulating coating provided on the outer periphery, or may have another layer on the insulating coating. It may be provided with a resin film (such as a fusion film). Examples of the insulating film include polyurethane resin, polyester resin, polyesterimide resin, etc., and examples of the fusion film include nylon resin, epoxy resin, etc. When providing an insulating film, the thickness of the insulating film is not particularly limited, but it may be thicker as the wire diameter is larger and thinner as the wire diameter is smaller, as long as it is within the range of 1 to 10 μm depending on the wire diameter. When a fusion coating is provided on an insulation coating, the thickness of the fusion coating is not particularly limited, but as with the insulation coating, the larger the wire diameter, the thicker the smaller the wire diameter. It is sufficient that the thickness is appropriate. By providing an insulating film, the insulation, oxidation resistance, and weather resistance of each single wire can be improved. Further, by providing the fusion film, the fusion to the resin sheet 2 can be more easily performed, and the exothermic wire 1 can be easily joined to the resin sheet 2. Note that when the heating wire 1 is embedded between the two resin sheets 2a and 2b, it may be heated to about 150 to 200°C, so the insulating film should be made of a material that does not deteriorate at such temperatures. Preferably, the fusion coating is made of a material that exhibits fusion performance at such temperatures.

The diameter d of the heating wire 1 is preferably within the range of 1/20 (=0.05) or more and 1/2 (=0.5) or less of the thickness of the heating sheet 10. Since the diameter d of the heating wire 1 was defined in relation to the thickness of the heating sheet 10, if the diameter d of the heating wire 1 is small, about 1/20 of the thickness of the heating sheet 10, heat will be generated from the surface of the heating wire 1. Since the distance D to the surface of the sheet 10 becomes longer, it is preferable from the point of view that the insulation property can be improved. The distance D from the surface of the heat generating sheet 10 to the surface of the heat generating sheet 10 is shortened, which is preferable in that heat can be easily transferred to the surface of the heat generating sheet 10. As a result, there is a special effect in that snow and the like adhering to the decorative component 20 can be melted quickly and with energy savings. When the diameter d of the heating wire 1 becomes thicker than 1/2 of the thickness of the heating sheet 10, the distance D to the surface of the heating sheet 10 becomes short and heat is quickly conducted. If this is too high, the insulation properties and the strength of the heat generating sheet 10 may deteriorate, making it unsatisfactory in terms of practical use. On the other hand, if the diameter d of the heating wire 1 becomes thinner than 1/20 of the thickness of the heating sheet 10, the distance D to the surface of the heating sheet 10 becomes long, making it difficult for heat to be quickly conducted to the surface. There are cases.

It is preferable that the projected area ratio of the portion of the heat generating sheet 10 through which the millimeter waves 22 pass through the heat generating line 1 is within the range of 0.2 to 5.0%. By setting the projected area ratio within the above range, the projected area shielded by the heat generating line 1 becomes small, suppressing a decrease in attenuation when the millimeter wave 22 is transmitted, and improving the appearance of the decorative component 20. It has the advantage of not damaging the In particular, the heating wire 1 made of a round wire has the advantage that the heating wire 1 is less noticeable when viewed from above compared to a rectangular wire having the same cross-sectional area, and does not spoil the appearance of the decorative component 20. If the projected area ratio is less than 0.2%, the ratio of the wiring pattern of the heat generating lines 1 in the heat generating sheet 10 is too small, and snow melting etc. may not be performed effectively. On the other hand, if the projected area exceeds 5.0%, there is a risk that attenuation when the millimeter waves 22 are transmitted becomes large, and the appearance of the decorative component 20 may be impaired.

3 and 4 are examples of wiring patterns of the heat generating sheet 10. The heating sheet 10 has a wiring pattern formed by wiring the heating wires 1, but the wiring pattern is not particularly limited and must be a pattern that can effectively melt snow on the surface of the decorative component 20. is desirable. For example, the wiring patterns illustrated in FIGS. 3 and 4 can be used. Preferably, as shown in FIG. 5, the heat generating sheet 10 is wired with a projected area in the range of 0.2 to 5.0%, which does not suppress the transmission of the millimeter waves 22 emitted from the millimeter wave radar device 21. Preferably.

(resin sheet)
The resin sheet 2 is composed of at least two sheets, and forms the heat generating sheet 10 with the heat generating wire 1 sandwiched therebetween. At least two resin sheets 2 sandwich the heating wire 1 between them, and are configured such that the distance D from the surface of the heating wire 1 to the surface of the heating sheet 10 is within the range of 0.025 to 0.4925 mm. . By setting this distance range, the thickness of the heating sheet 10 for decorative parts can be controlled even when any of the heating wires 1 in the above diameter range (including those provided with an insulating film or a fusion film) is adopted. It can be within a range of about 0.2 to 1.0 mm.

The resin sheet 2 is a sheet-like material made of resin in which the heating wire 1 is arranged at the center or approximately at the center in the thickness direction Y. In order to arrange the heating wire 1 at the center or approximately the center in the thickness direction Y, the heating wire 1 is sandwiched between two resin sheets 2 (2a, 2b) having the same thickness Ta and Tb from above and below. An example of such a method is to heat the surface of the first resin sheet 2a to soften it, embed the heating wire 1 heated to about 150° C. to 200° C. to about half the extent, and then heat the surface. The heat generating sheet 10 having the cross-sectional form shown in FIG. 1 can be produced by bonding the second resin sheet 2b softened by the heating process onto the first resin sheet 2a in which the heat generating wire 1 is half embedded. can. Note that the production of the heat generating sheet 10 is not limited to this example, and may be produced by arbitrarily selecting other means.

The type of resin sheet 2 is not particularly limited, and may be either a thermoplastic resin or a thermosetting resin, but a thermoplastic resin that can soften the surface of each resin sheet 2a, 2b by heating as described above is preferable. As the thermoplastic resin, since the heat generating sheet 10 is bonded to the surface F of the vehicle decorative part, a resin material with good weather resistance is preferable, and examples thereof include polyester resins such as polyethylene terephthalate, polycarbonate resins, vinyl chloride resins, etc. be able to.

The thicknesses Ta and Tb of each resin sheet 2a and 2b are designed so that the diameter d of the heating wire 1 is 1/20 or more and 1/2 or less of the total thickness T of the resin sheet 2, as described above. It is preferable. That is, in the heat generating sheet 10 according to the present invention, it is desirable that the total thickness T of the resin sheet 2 is designed in relation to the diameter d of the heat generating wire 1. As a result, the heat generated by the heat generating wire 1 is Heat can be quickly conducted to the surface of each resin sheet 2a, 2b, and snow and the like adhering to the decorative component 20 can be quickly melted with energy saving, which is a special effect. Note that since the resin sheet 2 is constructed by pasting together two resin sheets 2a and 2b with the same thickness Ta and Tb, the thicknesses Ta and Tb of each resin sheet 2a and 2b are determined by the heating wire. This is 1/2 of the total thickness T of the resin sheet 2 designed in relation to the diameter d of 1.

By making the thicknesses Ta and Tb of the two resin sheets 2a and 2b the same, the heating wire 1 is arranged at the center of the resin sheet 2 in the thickness direction Y. Therefore, the heating wire 1 can be stably held in the middle part of the resin sheet 2 in the thickness direction Y, and stress is not applied to the heating wire 1 during manufacturing or when attaching it to the surface F of a vehicle decorative part. Even if the heating wire 1 is damaged or disconnected, it is possible to prevent the heating wire 1 from being damaged or disconnected. Furthermore, when the heat generating sheet 10 is attached to the surface F of a vehicle decorative part, the surface of the heat generating sheet 10 will be exposed to the outermost part, and there is a risk that sand etc. will collide with it or that UV deterioration will occur. Because of this, it is not possible to make it too thin. Furthermore, if the resin sheet on the back side is made thinner, there is a possibility that the resin sheet on the back side will come into contact with decorative parts made of metal with good thermal conductivity, and in that case, heat will be generated from the side of the thin resin sheet. It is also possible that snow and the like attached to the surface that is not in contact with the metal will be difficult to melt. For these reasons, it is preferable that the two resin sheets 2a and 2b have the same thickness Ta and Tb.

As a specific example, the thicknesses Ta and Tb of each resin sheet 2a and 2b are preferably within a range of about 0.1 to 0.5 mm. If the thickness Ta, Tb of each resin sheet 2a, 2b is less than 0.1 mm, it is too thin and there is a risk that the above-mentioned problems caused by thinning may occur. On the other hand, if the thicknesses Ta and Tb of each resin sheet 2a and 2b exceed 0.5 mm, heat conduction to the surface of the heat generating sheet 10 will decrease, making it difficult to quickly melt snow, and also being undesirable from the viewpoint of energy saving. Sometimes enough is enough. Moreover, since the heating wire 1 is arranged at the center of the resin sheet 2 in the thickness direction Y, stable insulation can also be ensured.

Note that a transparent film heater is known as a prior art similar to the present invention, and this transparent film heater uses a conductive material such as ITO (indium tin oxide) or tin oxide on a transparent film substrate such as PET. A transparent heat generating layer made of a metal oxide is provided by a film forming method such as a sputtering method. However, transparent film heaters have the disadvantage that the transparent heat generating layer has a large resistance, and as the size increases, the total resistance value increases, and a high voltage power source is required. On the other hand, the heating sheet for decorative parts according to the present invention can be manufactured by an easy manufacturing method of providing the heating wire 1 between two resin sheets 2a and 2b, and the heating wire 1 with good conductivity can The advantage is that the total resistance value is unlikely to increase even if the size is increased.

It does not matter whether the resin sheet 2 is transparent or not. When it is transparent, it is more preferable because it does not easily spoil the appearance of the decorative component 20. The transparency may be colorless or colored, and can be selected depending on the vehicle decorative part to which the heat generating sheet 10 is attached. Further, depending on the vehicle decorative part to which the heat generating sheet 10 is attached, it may not be transparent, and may be translucent or opaque.

(heat generating sheet)
As shown in FIG. 5, the heat generating sheet 10 is attached to the front surface F of the vehicle decorative component 20 in the transmission direction of the millimeter wave 22 transmitted from the millimeter wave radar device 21. By providing this heat generating sheet 10 on the surface F of the decorative component 20, there is no need for heat to pass through the decorative component 20, the heat conduction efficiency is good, and snow etc. attached to the decorative component 20 can be easily melted. can. As a result, snow can be melted quickly and with less energy.

In the heat generating sheet 10, an arbitrary functional layer (including a functional film; the same applies hereinafter) can be provided on one or both sides of the resin sheet 2 with the heat generating wire 1 sandwiched therebetween. For example, an adhesive layer or an adhesive layer for fixing to the vehicle decorative component is preferably provided on the surface of the vehicle decorative component. The surface opposite to the vehicle decorative parts side is coated with a weather-resistant UV protection layer, a hard coat layer to provide scratch resistance and scratch resistance, and a hard coat layer to improve the adhesion between these functional layers and the resin sheet. A primer layer etc. can be provided as desired. The thickness of these functional layers is not particularly limited and can be provided by arbitrarily selecting a conventionally known thickness, but if it is too thick, the heat generating line 1 will be placed at the center or approximately the center of the heat generating sheet 10 in the thickness direction Y. Therefore, it is desirable to design the thickness to a level that does not affect heat transfer.

The thickness of the heat generating sheet 10 is preferably within the range of 0.2 to 1.0 mm after the above-mentioned optional functional layer is provided. By setting the thickness within this range, heat can be efficiently transmitted to the surface of the decorative component.

(Vehicle decorative parts)
The decorative component 20 according to the present invention is a vehicle decorative component 20 provided with a millimeter wave radar device 21, as shown in FIG. The heating sheet 10 for decorative parts according to the present invention is attached to the front in the transmission direction of the millimeter waves 22 transmitted from. Since the decorative component 20 has the heat-generating sheet 10 provided as a cover member on the surface F, the heat from the heat-generating sheet 10 can easily melt adhering snow and the like.

The present invention will be explained in more detail below using experimental examples.

[Experiment 1]
The heating wire 1 includes a copper wire with a diameter d of 0.05 mm, an insulating film made of polyurethane resin with a thickness of 4 μm provided on the copper wire, and a nylon film with a thickness of 4.5 μm provided on the insulating film. A fusion film made of resin was used. For the resin sheet 2, polycarbonate films having thicknesses Ta and Tb of 0.15 mm were used as the resin sheets 2a and 2b. When wiring the heating wire 1 on the surface of one resin sheet 2a in the wiring pattern shown in FIG. 3, the heating wire 1 is heated by ultrasonic waves while the surface of the resin sheet 2a is heated and softened, The heating wire 1 was embedded into the surface to about half the diameter. Thereafter, while the surface of another resin sheet 2b was heated, it was pasted onto the resin sheet 2a in which the heating wire 1 was half embedded, to produce the heating sheet 10.

Regarding the produced heat generating sheet 10, the resistance value was measured, and the current, electric power, and surface temperature when a predetermined applied voltage was applied were measured. Note that the surface temperature was measured on the surface of the resin sheet 2b, which is the surface opposite to the decorative component side. The results are shown in Table 1.

[Experiment 2]
The heating wire 1 includes a copper wire with a diameter d of 0.14 mm, an insulating film made of polyurethane resin with a thickness of 6 μm provided on the copper wire, and a nylon film with a thickness of 4.5 μm provided on the insulating film. A fusion film made of resin was used. For the resin sheet 2, polycarbonate films having thicknesses Ta and Tb of 0.15 mm were used as the resin sheets 2a and 2b. The heat generating sheet 10 was produced in the same manner as in Experiment 1 except for the above. Table 1 also shows the results of the properties of the produced heat generating sheet 10.

[Experiment 3]
As the heating wire 1, a 10 mass % silver-containing copper wire with a diameter d of 0.016 mm, an insulating film made of a polyurethane resin with a thickness of 1.5 μm provided on the copper wire, and an insulating film provided on the insulating film. A fusion film made of nylon resin with a thickness of 1 μm was used. For the resin sheet 2, polycarbonate films having thicknesses Ta and Tb of 0.15 mm were used as the resin sheets 2a and 2b. The wiring pattern was as shown in FIG. 4. The heat generating sheet 10 was produced in the same manner as in Experiment 1 except for the above. Table 1 also shows the results of the properties of the produced heat generating sheet 10. In this experiment 3, the results were shown using two types of applied voltages: 36.4V and 45.1V.

[Experiment 4]
The heating wire 1 is made of a copper wire with a diameter d of 0.11 mm, an insulating film made of polyurethane resin with a thickness of 5 μm provided on the copper wire, and a nylon resin with a thickness of 5 μm provided on the insulating film. A fusion film composed of the following was used. For the resin sheet 2, PVC films having thicknesses Ta and Tb of 0.4 mm were used as the resin sheets 2a and 2b. The heat generating sheet 10 was produced in the same manner as in Experiment 1 except for the above. Table 2 shows the results of the properties of the produced heat generating sheet 10. In this experiment 4, the results were shown using two types of applied voltages: 1.5V and 1.7V.

[Experiments 5-12]
Experiments 5 to 12 are the results when the wire diameter of the heating wire 1, the thicknesses Ta and Tb of each resin sheet 2a and 2b, and the projected area ratio were variously changed. The results are shown in Table 3 together with the results of Experiments 1 to 4 above. Furthermore, in Experiments 5 to 13, copper wires of each diameter d were used as the heating wires 1, and on the copper wires, an insulating film made of polyurethane resin and a fusion film made of nylon resin were coated with a thickness corresponding to the diameter. The one with a film was used. As the resin sheets 2a and 2b, polycarbonate films having respective thicknesses Ta and Tb were used. The projected area ratio was set to the values shown in Table 3 by changing the wiring pattern of the heating wire 1.

Table 4 shows the characteristic results in Experiments 1 to 13. In Table 4, the appearance was evaluated by visual inspection and was evaluated as "○" if it was not noticeable, and "△" if it was slightly noticeable. Heating was carried out by changing the appropriate applied voltage depending on the wire diameter, and the quality of heat transfer to the surface at that time was evaluated by sensory evaluation, and a good case was given a "○", and a slightly insufficient case was given a "○". △" Although insulation properties were not evaluated based on withstand voltage, cases in which the distance D was sufficient and there was no concern about insulation properties were marked as "○", and cases in which there was some concern were marked as "△".

1 Heat generating wires 2, 2a, 2b Resin sheet 10 Heat generating sheet 20 Vehicle decorative parts 21 Millimeter wave radar device 22 Millimeter waves F Surface of vehicle decorative parts T Total thickness of resin sheet Ta, Tb Thickness of resin sheet Y Heat generation Thickness direction of the sheet D Distance from the surface of the heating wire to the surface of the heating sheet d Diameter of the heating wire

Claims (5)

A heat-generating sheet attached to the front of a vehicle decorative part in the direction of transmission of millimeter waves transmitted from a millimeter-wave radar device, the heat-generating wire having a wire-drawn diameter within the range of 0.015 to 0.15 mm. and at least two resin sheets sandwiching the heating wire, wherein the two resin sheets sandwiching the heating wire have the same or substantially the same thickness, and the two resin sheets have the same thickness. Half of the heating wire is embedded in each of the heating sheets, the heating wire is arranged at the center of the heating sheet in the thickness direction, and the distance from the surface of the heating wire to the surface of the heating sheet is 0. 0.025 to 0.4925 mm, and the diameter of the heating wire is within the range of 1/20 or more and 1/2 or less of the thickness of the heating sheet. . The heat-generating wire is formed by heating and softening one of the two resin sheets and embedding it halfway, and heating and softening the other resin sheet and bonding it over it. Heat generating sheet for decorative parts. The heat generating sheet for decorative parts according to claim 1 or 2, wherein the heat generating wire is a copper wire, a copper alloy wire, a plated copper wire, or a plated copper alloy wire. The heating sheet for decorative parts according to any one of claims 1 to 3, wherein a projected area ratio of the heating line in the portion through which the millimeter wave passes is within a range of 0.2 to 5.0%. 2. The method for manufacturing a heat generating sheet according to claim 1, wherein the surface of the first resin sheet of the two resin sheets is heated and softened, and the heat generating wire is embedded halfway, and then, Production of a heat-generating sheet for decorative parts, characterized in that a second resin sheet whose surface has been softened by heating is pasted onto the first resin sheet in which the heat-generating wires are half-embedded. Method.

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