Linear bodies and planar units

Abstract

To provide a linear body capable of increasing heat generation, and a planar unit using the linear body. [Solution] A linear body 10 having a plurality of conductor strands 5a, 6a and a core wire 3, wherein the plurality of conductor strands 5a, 6a are aligned and wound on the core wire 3, the winding is laminated and has an inner layer and an outer layer, the gap between the conductor strands 5a of the inner layer is greater than 0.009 mm, the gap between the conductor strands 5a of the inner layer is less than or equal to the diameter of the conductor strands 5a of the inner layer, and the gap between the conductor strands of the inner layer 5a is less than or equal to the diameter of the conductor strands 6a of the outer layer,

Description

Technical Field

[0001] The present invention relates to a linear body that can be suitably used as a heater wire for an electric blanket, an electric carpet, a car seat heater, a steering heater, etc., and a sensor wire that can be suitably used for contact detection and temperature detection of a car seat and a steering wheel. In particular, the present invention relates to a linear body capable of improving the calorific value and a planar unit using the linear body.

Background Art

[0002] The linear body is used as a heater wire for an electric blanket, an electric carpet, a car seat heater, a steering heater, etc. Generally known heater wires are formed by first spirally winding a plurality of conductor strands around a core wire and then covering it with an outer coating made of an insulator layer. The heater wire is formed by aligning a plurality of conductor strands such as copper wires or nickel-chromium alloy wires, or by twisting a plurality of these conductor strands together. A heat-sealing member is formed on the outer periphery of the heater wire, and by this heat-sealing member, the heater wire is adhered to a base material made of, for example, a non-woven fabric or an aluminum foil (see, for example, Patent Document 1).

[0003] When the conductor strand is pulled or bent, a part of the conductor strand may break. Conventionally, since each conductor strand of the heater wire is in contact with each other, when a part of the conductor strand breaks, the diameter of the heater wire becomes thinner at the broken part. Since the current amount per unit cross-sectional area increases at the part where the diameter of the heater wire becomes thinner, this part may generate more heat than usual. In another example, when the heater wire is formed by individually forming an insulating film on each conductor strand, each conductor strand forms a parallel circuit. In the case of this heater wire, when a disconnection occurs in a part of the conductor strand, a part of the parallel circuit is disconnected. In the case of this heater wire, excessive heat generation can be prevented (see, for example, Patent Document 2, Patent Document 3, etc.).

[0004] In recent years, in order to improve the rapid heating of heater wires, there has been a demand for aligning the conductor strands with a narrower winding pitch, and in such cases, designs have been devised in which the conductor strands are wound horizontally in a spiral at a high density (see, for example, Patent Document 4).

[0005] Furthermore, patent documents 5 to 7 have been filed by the applicant as technologies related to the present invention. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2003-174952: Kurabe [Patent Document 2] Japanese Patent Publication No. 61-47087: Matsushita Electric Industrial Co., Ltd. [Patent Document 3] Japanese Patent Publication No. 2008-311111: Kurabe [Patent Document 4] Japanese Patent Publication No. 2021-190171: TOTOKU [Patent Document 5] Japanese Patent Publication No. 2010-15691: Kurabe [Patent Document 6] International Publication WO2011 / 001953: Krabe [Patent Document 7] International Publication WO2022 / 054701: Krabe [Disclosure of the Invention] [Problems that the invention aims to solve]

[0007] In conventional linear materials and heater wires, multiple conductor strands are all in a single-winding structure. In the case of heater wires for automotive applications, the voltage is applied at a constant level, so the amount of heat generated depends on the resistance of the conductor strands. The resistance of the conductor strands depends on the diameter and length of the conductor strands, and the length of the conductor strands depends on the pattern shape in which the heater wires are arranged and the winding pitch of the conductor strands. The pattern shape in which the heater wires are arranged is subject to significant design constraints as it depends on the shape and size of the heated area. Furthermore, while it is conceivable to design the resistance of the conductor strands, and thus the amount of heat generated by the heater wire, based on the diameter of the conductor strands, there are standards for the diameter of conductor strands, and it is difficult to manufacture a wide variety of conductor strands with finely divided diameters during the manufacturing process. In addition, if thicker conductor strands are used to obtain high heat generation with low resistance, the flexibility of the heater wire deteriorates. For these reasons, it has been difficult to manufacture heater wires with low resistance, i.e., high heat generation.

[0008] This invention was made to solve the problems of the prior art, and its objective is to provide a linear body and a planar unit using the same, which can be easily designed to have low resistance values ​​by using a multi-layer winding structure for the conductor strands. [Means for solving the problem]

[0009] To achieve the above objective, the linear body according to the present invention is a linear body having a plurality of conductor strands and a core wire, wherein the plurality of conductor strands are aligned and wound on the core wire, the winding is laminated and has an inner layer and an outer layer, the gap between the conductor strands of the inner layer is greater than 0.009 mm, the gap between the conductor strands of the inner layer is less than or equal to the wire diameter of the conductor strands of the inner layer, and the gap between the conductor strands of the inner layer is less than or equal to the wire diameter of the conductor strands of the outer layer. Furthermore, it is possible that the gaps between the conductor strands in the outer layer are greater than 0.031 mm. Furthermore, it is possible that the conductor strands of the inner layer have a diameter 0.6 to 1.4 times that of the conductor strands of the outer layer. Also, it is conceivable that a plurality of conductor strands are insulated. Also, it is conceivable that the inner peripheral layer and the outer peripheral layer are adjacent to each other.

Advantages of the Invention

[0010] Since the winding of the conductor strands of the linear body of the present invention has a plurality of layers, it is possible to achieve a lower resistance value of the target conductor strands, that is, to manufacture a heater wire with a high calorific value.

Brief Description of the Drawings

[0011] [Figure 1] It is a figure showing an embodiment according to the present invention, and is a partially cut-away side view showing the configuration of the linear body. [Figure 2] It is a figure showing an embodiment according to the present invention, and is a partially cut-away side view showing the configuration of a conductor strand with an insulating film formed thereon. [Figure 3] It is a figure showing the configuration of a hot press type planar unit manufacturing apparatus used in the present invention. [Figure 4] In the planar unit of the present invention, it is a partially perspective view showing a state in which a linear body is arranged in a predetermined pattern shape. [Figure 5] It is a plan view showing the configuration of the planar unit according to the present invention. [Figure 6] It is a plan view showing the configuration of the planar unit according to the present invention. [Figure 7] It is a perspective view showing a state in which the planar unit according to the present invention is partially cut away and embedded in a vehicle seat. [Figure 8] It is a perspective view showing a state in which the planar unit according to the present invention is partially cut away and embedded in a steering wheel.

Best Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. These embodiments show examples assuming that the linear body of the present invention, that is, the heater wire, is used as a planar unit and applied to a vehicle seat heater.

[0013] First, this embodiment will be described with reference to Figure 1. The configuration of the linear body 10 in this embodiment will be described first. The linear body 10 in this embodiment has the configuration shown in Figures 1 and 2. First, the core wire 3 is formed of an aromatic polyamide fiber bundle with an outer diameter of 0.21 mm. Eight conductor strands 5a, which are hard tin-filled copper alloy wires with a strand diameter of 0.08 mm, are arranged and wound spirally around the outer circumference of the core wire 3 with a winding pitch of 1.2 mm. As shown in Figure 2, an insulating coating 5b is formed around the conductor strands 5a. The insulating coating 5b is formed of an inner layer 5c made of polyurethane resin and an outer layer 5d made of polyamide-imide resin. The inner layer 5c of the insulating coating 5b is formed to be a layer with a thickness of approximately 3 μm by applying polyurethane varnish around the conductor strands 5a and drying it. Next, the outer coating layer 5d was formed by applying polyamide-imide varnish to the outer circumference of the inner coating layer 5c and drying it to form a layer approximately 2.5 μm thick. Nine conductor strands 6a, which are hard tin-filled copper alloy wires with a wire diameter of 0.08 mm, are arranged and wound spirally around the outer circumference of the wound conductor strand 5a with a winding pitch of 1.2 mm. As shown in Figure 2, an insulating coating 6b is formed around the conductor strand 6a. The insulating coating 6b is formed from an inner coating layer 6c made of polyurethane resin and an outer coating layer 6d made of polyamide-imide resin. The inner coating layer 6c of the insulating coating 6b was formed by applying polyurethane varnish to the outer circumference of the conductor strand 6a and drying it to form a layer approximately 3 μm thick. Next, the outer coating layer 6d was formed by applying polyamide-imide varnish to the outer circumference of the inner coating layer 5c and drying it to form a layer approximately 2.5 μm thick. The outer circumference of the core wire 3, which is wound with conductor strands 5a and 6a, is covered with an insulating layer 7. The insulating layer 7 is formed by extruding a polyester thermoplastic elastomer containing a flame retardant to a thickness of approximately 0.3 mm. In this embodiment, the polyester thermoplastic elastomer of the insulating layer 7 also functions as a heat-sealable layer. The finished outer diameter of the above-described linear body 10 is approximately 1.2 mm. The core wire 3 is effective in that it increases flexibility and tensile strength. It is also possible to use multiple conductor strands aligned or twisted together without using the core wire 3.

[0014] Next, the structure of the base material 11 for adhering and fixing the linear body 10 having the above structure will be described. The base material 11 in this embodiment is a non-woven fabric (basis weight: 100 g / m 2 , thickness: 0.6 mm) formed by mixing 10% of heat-fusible fibers having a core-sheath structure with a low-melting-point polyester as a sheath component and 90% of flame-retardant fibers made of flame-retardant polyester fibers. This base material 11 is formed into a desired shape by a known method such as die-cutting.

[0015] Next, the structure in which the linear body 10 is arranged on the base material 11 in a predetermined pattern shape and adhered and fixed will be described. FIG. 3 is a diagram showing the structure of a hot press type heater manufacturing apparatus 13 for adhering and fixing the linear body 10 on the base material 11. First, the hot press jig 15 will be described. A plurality of locking mechanisms 17 are arranged on the upper surface of this hot press jig 15. As shown in FIG. 4, the locking mechanism 17 includes a pin 19, and this pin 19 is inserted into a hole 21 drilled in the hot press jig 15 from below upward. A locking member 23 is attached to the upper surface of this pin 19 so as to be movable in the axial direction of the pin 19, and the locking member 23 is constantly urged upward by a coil spring 25. Then, as shown by the phantom line in FIG. 4, the linear body 10 is arranged in a predetermined pattern shape corresponding to the position of the locking member 23 while being locked to the locking members 23 on the upper surfaces of the plurality of locking mechanisms 17.

[0016] Returning to Figure 3, a press heating plate 27 is positioned above the multiple locking mechanisms 17 so as to be able to move up and down. First, the linear body 10 is arranged to draw a predetermined pattern shape while being hooked onto the locking members 23 of the multiple locking mechanisms 17, and then the base material 11 is placed on top of the linear body. In this state, the press heating plate 27 descends and presses the base material 11 against the linear body 10. At this time, for example, the press heating plate 27 applies heating and pressure to the base material 11 and the linear body 10 at 230°C for 5 seconds. As a result, the heat-fusible layer of the linear body 10 and the heat-fusible fibers of the base material 11 are both heated and pressurized and fuse together. As a result, the linear body 10 and the base material 11 are bonded and fixed. During the heating and pressurizing process, the press heating plate 27 moves downward against the biasing force of the coil springs 25 of the locking members 23 of the multiple locking mechanisms 17.

[0017] On the surfaces of the base material 11 where the linear body 10 is not placed, an adhesive layer may be formed, or double-sided tape may be applied. These adhesive layers or double-sided tapes are used when fixing the base material 11 to the seat.

[0018] By performing the above work, a planar unit 31 for a vehicle seat heater, as shown in Figure 5, can be obtained. The lead wires 40 are connected to both ends of the linear body 10 in the planar unit 31 and to the temperature control device 39 via connection terminals (not shown). The linear body 10, the temperature control device 39, and the connector 35 are connected to each other by the lead wires 40. The connection of the linear body 10 and the lead wires 40 by these connection terminals will be described in detail below. At the ends of the linear body 10, the insulating layer 7 of the linear body 10 is removed by a stripping machine to expose the heating wire 1. Similarly, at the ends of the lead wires 40, the insulation of the lead wires 40 is removed by a stripping machine to expose the conductor. The ends of the linear body 10 with the heating wire 1 exposed and the ends of the lead wires 40 with the conductor exposed are soldered to the connection terminals. In this way, the linear body 10, the lead wires 40, and the connection terminals are connected to each other. The insulating coatings 5b and 6b formed on the conductor strands 5a and 6a of the linear body 10 are removed by the heat of soldering, and the conductor strands 5a and 6a are electrically connected to the conductor of the lead wire 40. The mechanism of this operation will be explained in detail below. The soldering temperature is approximately 360°C. This temperature is higher than the thermal decomposition of the polyurethane resin that constitutes the inner layers 5c and 6c of the coating, so the inner layers 5c and 6c undergo thermal decomposition. On the other hand, this temperature of 360°C is below the melting point and thermal decomposition temperature of the polyamide-imide resin that constitutes the outer layers 5d and 6d of the coating. That is, when the conductor strands 5a and 6a are heated at the soldering temperature, the inner layer 5c of the insulating coating 5b and the inner layer 6c of the insulating coating 6b undergo thermal decomposition, and spaces are formed between the outer layer 5d of the insulating coating 5b and the conductor strand 5a, and between the outer layer 6d of the insulating coating 6b and the conductor strand 6a. Furthermore, the outer coating layers 5d and 6d are applied around the inner coating layers 5c and 6c and then undergo a drying process. As a result, the outer coating layers 5d and 6d are in a stretched state, and therefore residual stress in the compressive direction is generated in the outer coating layers 5d and 6d. At the ends of the linear body 10, if the outer coating layer 5d of the insulating coating 5b and the conductor wire 5a, and the outer coating layer 6d of the insulating coating 6b and the conductor wire 6a are not in close contact, the insulating coatings 5b and 6d are heated and shrink. Consequently, the ends of the conductor wires 5a and 6a are naturally exposed.As described above, the ends of the conductor strands 5a and 6a are naturally exposed, eliminating the need to polish the ends of the conductor strands 5a and 6a to remove the insulating coatings 5b and 6b. This greatly improves the workability of the ends of the conductor strands 5a and 6a. The wire body 10 is connected to the electrical system of a vehicle (not shown) via the connector 35.

[0019] In this embodiment, due to the specifications of the heat generation characteristics of the planar unit 31, the resistance value of the linear body 10 is required to be 0.3 to 0.55 Ω / m. Since the resistivity of the materials of the conductor strands 5a and 6a is 2.30 μΩ·m, as described above, the resistance value of the linear body 10 can be designed to be 0.3 Ω / m by combining eight conductor strands 5a with a wire diameter of 0.08 mm and nine conductor strands 6a with a wire diameter of 0.08 mm and winding them spirally on a core wire 3 with an outer diameter of approximately 0.21 mm at a winding pitch of 1.2 mm, or by combining eight conductor strands 5a with a wire diameter of 0.08 mm and eight conductor strands 6a with a wire diameter of 0.1 mm. By combining a and winding it spirally on a core wire 3 with an outer diameter of approximately 0.21 mm at a winding pitch of 1.2 mm, the resistance of the linear body 10 can be designed to be 0.3 Ω / m. Alternatively, by combining seven conductor strands 5a with a wire diameter of 0.08 mm and five conductor strands 6a with a wire diameter of 0.08 mm and winding them spirally on a core wire 3 with an outer diameter of approximately 0.21 mm at a winding pitch of 0.9 mm, the resistance of the linear body 10 can be designed to be 0.55 Ω / m.

[0020] The planar unit 31 is then positioned embedded within the vehicle seat 41, as shown in Figure 7. That is, as described above, the planar unit 31 is attached to the surface cover 43 or seat pad 45 of the vehicle seat 41.

[0021] The linear body 10 arranged on the planar unit 31 obtained in this manner was used as a sample and evaluated using an evaluation method based on its appearance. The results are shown in Table 1.

[0022] [Table 1]

[0023] The visual inspection method involves visually checking whether there are any overlaps or saggings in the wound conductor strands. If there are no overlaps or saggings, it is evaluated as ○; if there are overlaps or saggings, it is evaluated as ×.

[0024] As shown in Table 1, the linear body 10 according to the above-described embodiment has a predetermined resistance value and passes the visual inspection. In contrast, comparative examples 1 and 2, in which the gaps between the conductor strands of the inner layer were approximately the same as the wire diameter of the conductor strands of the inner and outer layers, failed the visual inspection because overlapping and sagging occurred in the wound conductor strands.

[0025] Examples of the core wire 3 include monofilaments, multifilaments, spuns, or other fiber materials of inorganic fibers such as glass fibers, or organic fibers such as polyethylene terephthalate, aliphatic polyamide fibers, aromatic polyamide fibers, and fully aromatic polyester fibers, or fibers having a core material made of such organic polymer materials, with a thermoplastic organic polymer material covering its circumference. Furthermore, when a core wire 3 with heat shrinkability and heat meltability is used, if the conductor strands 5a and 6a break and overheat abnormally, the core wire 3 melts, breaks, and shrinks. When the core wire 3 shrinks, the conductor strands 5a and 6a wound around the core wire 3 follow the movement of the core wire 3, causing the ends of the broken conductor strands 5a and 6a to separate. As a result, the ends of the broken conductor strands 5a and 6a no longer repeatedly touch and separate. In addition, the ends of the broken conductor strands 5a and 6a no longer make contact with each other with only a small contact area, such as a point contact. This prevents abnormal heat generation. Furthermore, if the conductor strands 5a and 6a are insulated by the insulating coatings 5b and 6b, the core wire 3 does not need to be made of insulating material. For example, stainless steel wire or titanium alloy wire can be used as the core wire 3. However, since there is a possibility of the conductor strands 5a and 6a breaking, it is better for the core wire 3 to be made of insulating material.

[0026] Conventional known materials can be used as the conductor strands 5a and 6a, such as copper wire, copper alloy wire, nickel wire, iron wire, aluminum wire, nickel-chromium alloy wire, and iron-chromium alloy wire. Examples of copper alloy wires include tin-copper alloy wire, copper-nickel alloy wire, and silver-containing copper alloy wire in which copper solid solution and copper-silver eutectic are formed into fibers. Of these, copper wire or copper alloy wire is preferred from the viewpoint of balancing cost and properties. These copper wires or copper alloy wires come in soft and hard types, but from the viewpoint of bending resistance, the hard type is particularly preferred over the soft type. Hard copper wire and hard copper alloy wire are those in which individual metal crystal grains are stretched long in the processing direction by cold working such as wire drawing, resulting in a fibrous structure. When such hard copper wire or hard copper alloy wire is heated above the recrystallization temperature, the processing strain generated in the metal crystal is eliminated, and crystal nuclei that will serve as the starting points for new metal crystals begin to appear. These crystal nuclei develop and undergo recrystallization, sequentially replacing old crystal grains, resulting in further grain growth. Soft copper wire and soft copper alloy wire are in this state of crystal grain growth. Compared to hard copper wire and hard copper alloy wire, soft copper wire and soft copper alloy wire have higher elongation and electrical resistance, but lower tensile strength, resulting in lower bending resistance. Thus, since hard copper wire and hard copper alloy wire become soft copper wire or soft copper alloy wire with low bending resistance through heat treatment, it is preferable to perform processing with as little thermal history as possible. Furthermore, hard copper wire is defined in JIS-C3101 (1994) and soft copper wire in JIS-C3102 (1984). Soft copper wire is defined as having an elongation of 15% or more for outer diameters of 0.10 to 0.26 mm, 20% or more for outer diameters of 0.29 to 0.70 mm, 25% or more for outer diameters of 0.80 to 1.8 mm, and 30% or more for outer diameters of 2.0 to 7.0 mm. Copper wire also includes wires that have been tin-plated. Tin-plated hard copper wire is defined in JIS-C3151 (1994), and tin-plated soft copper wire is defined in JIS-C3152 (1984). In addition, various cross-sectional shapes can be used for conductor strands 5a and 6a, and are not limited to the commonly used circular cross-section; so-called flat rectangular wires may also be used.

[0027] There is no limit to the number of conductor strands 5a and 6a; for example, there may be only one conductor strand 5a with a large diameter, or only one conductor strand 5b with a small diameter. Furthermore, conductor strands 5a and 6a may be made of different materials. Also, conductor strands 5a and 6a may have insulating coatings 5b and 6b made of different materials. In addition, conductor strands 5a and 6a may be made of a combination of hard and soft materials.

[0028] Preferably, the gaps between each conductor strand 5a located in the inner circumferential layer are 0.009 mm or more, the gaps between each conductor strand are less than or equal to the wire diameter of the conductor strand 5a located in the inner circumferential layer, and the gaps between each conductor strand are less than or equal to the wire diameter of the conductor strand 6a located in the outer circumferential layer. This structure prevents overlapping of the conductor strands 5a located in the inner circumferential layer and prevents the conductor strand 6a located in the outer circumferential layer from falling into the gaps between the conductor strands 5a located in the inner circumferential layer, thereby enabling the manufacture of a low-resistance heater wire with a desirable appearance. If the gaps between each conductor strand in the inner circumferential layer are smaller than 0.009 mm, it will cause overlapping of the conductor strands 5a in the inner circumferential layer. If the gaps between each conductor strand in the inner circumferential layer are larger than the wire diameter of the conductor strand 5a, and if the gaps between each conductor strand in the inner circumferential layer are larger than the wire diameter of the conductor strand 6a, the conductor strand 6a in the outer circumferential layer may fall into the gaps between the conductor strands 5a located in the inner circumferential layer, which is undesirable in terms of appearance.

[0029] The average wire diameter of the conductor strands 5a located in the inner layer is preferably 0.6 to 1.4 times the average wire diameter of the conductor strands 6a located in the outer layer. If the average wire diameter of the conductor strands 5a is less than 0.6 times or greater than 1.4 times, the amount of springback of the conductor strands during lateral winding will differ between the inner and outer layers, disrupting the lateral winding structure. Furthermore, if the conductor strands are outside the wire diameter specifications, it is undesirable from a manufacturing process perspective.

[0030] The gap between each conductor strand 6a located in the outer layer is preferably 0.031 mm or more. This structure prevents overlapping of the conductor strands 6a located in the outer layer, making it possible to manufacture a low-resistance heater wire with a desirable appearance. If the gap between each conductor strand in the outer layer is smaller than 0.031 mm, overlapping of the conductor strands 6a in the outer layer occurs, which is undesirable in terms of appearance. It is also preferable that the gap between each conductor strand 6a located in the outer layer is less than or equal to the wire diameter of the conductor strands 6a located in the outer layer. If the gap between the conductor strands 6a in the outer layer is less than or equal to the wire diameter of the conductor strands 6a, no irregularities will occur in the heat-sealed portion that is extruded onto the outer periphery of the outer layer, and the fusion performance of the heat-sealed portion will be improved.

[0031] When winding conductor strands 5a and 6a onto the core wire 3, among the materials of the conductor strands 5a and 6a mentioned above, those with a small amount of springback when wound are preferable, and those with a recovery rate of 200% or less are desirable. For example, silver-containing copper alloy wire, in which copper solid solution and copper-silver eutectic form fibers, has excellent tensile strength and flexibility, but it is prone to springback when wound. Therefore, when winding onto the core wire 3, the conductor strands 5a and 6a are prone to lifting or breaking due to excessive winding tension, and are also prone to twisting after processing, which is undesirable. In particular, when the conductor strands 5a and 6a are covered with insulating coatings 5b and 6b, the restoring force of these insulating coatings 5b and 6b is also added. Therefore, it is important to select conductor strands 5a and 6a with a small recovery rate to compensate for the restoring force of the insulating coatings 5b and 6b.

[0032] Here, the measurement of the recovery rate as defined in this invention will be described in detail. First, while applying a constant load to the conductor wire, it is wrapped around a cylindrical mandrel with a diameter 60 times the diameter of the conductor wire three or more times so that the conductor wires do not overlap. After 10 minutes, the load is removed, the conductor wire is removed from the mandrel, and the inner diameter of the shape restored by elasticity is measured. The springback rate of the conductor wire is calculated using the following formula (I) and evaluated as the recovery rate. R = (d2 / d1) × 100 --- (I) Explanation of symbols: R: Recovery rate (%) d1: Mandrel diameter (mm) used in the winding test d2: Inner diameter (mm) of the shape after the conductor wires have been wound around the mandrel and the load has been released to restore it to its original state.

[0033] The insulating coatings 5b, 6b covering the conductor wires 5a, 6a may be formed by two layers, an inner coating layer 5c, 6c and an outer coating layer 5d, 6d, as in the above embodiment, or by three or more layers. However, the thermal decomposition temperature of the material constituting the inner coating layer must be lower than the lower of the melting point or thermal decomposition temperature of the material constituting the outer coating layer. Here, the inner coating layer is the layer formed on the conductor wires 5a, 6a. The outer coating layer only needs to be outside of this inner coating layer, so it is also possible to form other intermediate layers between the inner coating layer and the outer coating layer.

[0034] In the linear body 10, it is preferable that the insulating coating 5b covering the conductor strands 5a of the inner layer and the insulating coating 6b covering the conductor strands 6a of the outer layer are directly adjacent to each other. Direct adjacency allows for batch processing during soldering and suppresses the generation of foreign matter such as burnt residue. In addition, when the insulating coatings 5b and 6b are joined to each other when placed on the base material 11, interlayer displacement is suppressed, maintaining aesthetics and preventing deterioration of tactile feel. Furthermore, it is possible to reduce the diameter.

[0035] The materials for the insulating coatings 5b and 6b include a variety of materials such as polyurethane resin, polyamide resin, polyimide resin, polyamide-imide resin, polyester-imide resin, nylon resin, polyester-nylon resin, polyethylene resin, polystyrene resin, polypropylene resin, polyester resin, polybenzimidazole resin, vinyl chloride resin, fluororesin, and silicone resin. Multiple types of these materials may be used in combination, and various known additives such as flame retardants and anti-aging agents may be added. By combining these resins, the thermal decomposition temperature of the material constituting the inner layer of the coating is set to be lower than the lower of the melting point or thermal decomposition temperature of the material constituting the outer layer of the coating. The material for the inner layer of the coating can be selected from polyurethane resin, vinyl chloride resin, polyacetal resin, polystyrene resin, polypropylene resin, polymethyl methacrylate, polyester resins such as polyethylene terephthalate, polyvinyl alcohol, etc. In particular, it is preferable that the material for the inner layer of the coating is a thermosetting resin, and the material constituting the outer layer of the coating is a thermosetting resin. Here, the thermosetting resin also includes crosslinkable materials. From the viewpoint of heating characteristics as a cord-type heater and ease of terminal processing such as soldering, it is preferable that the material of the inner layer of the coating is polyurethane resin or polyester resin, and the material of the outer layer of the coating is any of polyimide resin, polyamide-imide resin, or silicone resin. In particular, it is preferable that the material of the inner layer of the coating is polyurethane resin and the material of the outer layer of the coating is polyamide-imide resin. This polyurethane resin may be, for example, an imide-containing polyurethane, or any other type that has undergone various modifications or formulations.

[0036] In the above structure, the inner layer of the coating decomposes at a temperature below the melting or decomposition temperature of the outer layer. Therefore, if the end of a conductor wire covered with an insulating coating is at a temperature above the decomposition temperature of the inner layer but below the lower of the melting point or decomposition temperature of the outer layer, only the inner layer will decompose, creating a space between the conductor wire and the insulating coating. On the other hand, when the outer layer of the coating is formed by extrusion or tape winding, it is formed by stretching in the longitudinal direction. Furthermore, when the outer layer of the coating is formed by coating and curing, a shrinkage force is generated during curing. That is, there is residual stress in the outer layer of the coating that compresses in the longitudinal direction. When the inner layer of the insulating coating of a conductor wire decomposes, a space is created between the insulating coating and the conductor wire. Furthermore, when heat is applied, the outer layer of the insulating coating shrinks. Through this process, for example, when the end of a conductor wire covered with an insulating coating is heated to a predetermined temperature, such as the melting point of solder, the insulating coating can be removed and the conductor wire exposed. This improves the processability of the terminals.

[0037] Furthermore, the factors that improve terminal processability can be explained as follows. Conductor wires expand when heated by contact with solder or the like. Insulating coatings, which are mainly made of resin or rubber materials, have a larger coefficient of thermal expansion than conductor wires, which are often mainly made of metal materials such as copper wire, copper alloy wire, or nickel wire. Therefore, the insulating coating expands more than the conductor wire, and a force is applied that tries to peel the insulating coating away from the conductor wire, causing cracks in the insulating coating. Solder or the like penetrates these cracks in the insulating coating, accelerating the thermal decomposition of the inner layer of the insulating coating. At the same time, when the inner layer of the coating decomposes, decomposing gases are generated, and these decomposing gases push the outer layer of the coating away from the conductor wire. Based on the above considerations, it is preferable that the insulating coating material has a large coefficient of thermal expansion. Also, if the temperature at which the material of the inner layer of the coating decomposes is below the glass transition temperature of the material constituting the outer layer of the coating, the outer layer of the coating will not become rubbery, and cracks will easily form in the outer layer of the coating.

[0038] Furthermore, other factors that improve terminal processability can be explained as follows: When solder or the like comes into contact and is heated, the inner layer of the insulating coating undergoes thermal decomposition. If the decomposing gas produced by thermal decomposition is a reducing gas such as hydrogen, carbon monoxide, aldehyde, or low molecular weight alkane, this reducing gas reduces the oxide film on the surface of the conductor wire. When the oxide film on the surface of the conductor wire is reduced, its wettability with solder or the like increases. When the wettability of the surface of the conductor wire is increased, solder or the like penetrates more easily between the conductor wire and the insulating coating, promoting thermal decomposition of the inner layer of the coating and peeling of the insulating coating, while also ensuring a secure bond between the solder or the like and the conductor wire. The urethane resin used as the material for the inner layers 5c and 6c of the coating in the above embodiment generates reducing gases when thermally decomposed. Alternatively, a material that generates reducing gases when thermally decomposed can be blended with various resins or rubbers, and the materials constituting the inner layers 5c and 6c of the coating can be these blended materials. These factors are speculations by the inventor and do not affect or limit the scope of the invention or patent rights.

[0039] The thickness of the inner layers 5c and 6c of the coating is preferably 4.0 μm or more. If it is less than 4.0 μm, the conductor wires 5a and 6a may corrode when used in an environment where corrosive liquids or gases are present, so it is necessary to form an additional insulating coating on the outer circumference of the insulating coatings 5b and 6b. It is also preferable that it be 5.0 μm or more. Furthermore, if the thickness of the inner layers 5c and 6c is too thin, even if the inner layers 5c and 6c are thermally decomposed, sufficient space may not be obtained between the conductor wires 5a and 6a and the outer layers 5d and 6d, and it may become impossible to remove the outer layers 5d and 6d. Furthermore, it is preferable that the thickness of the inner layers 5c and 6c is 7.0 μm or less. If the thickness of the inner layers 5c and 6c exceeds 7.0 μm, the amount of gas generated during the thermal decomposition of the inner layers 5c and 6c increases. For example, if the generated gas is combustible, it may adversely affect the flame retardancy, making it impossible to ignore the effects of the generated gas. The thickness of the outer coating layers 5d and 6d is preferably 4.0 μm or more. If it is less than 4.0 μm, the conductor wires 5a and 6a may corrode when used in an environment where corrosive liquids or gases are present, so it is necessary to form an additional insulating coating on the outer periphery of the insulating coatings 5b and 6b. It is also preferable that it be 5.0 μm or more. Furthermore, as mentioned above, the inner coating layers 5c and 6c decompose at relatively low temperatures, so if the thickness of the outer coating layers 5d and 6d is insufficient, it may not be possible to maintain insulating performance, especially at high temperatures. The thickness of the outer coating layers 5d and 6d is preferably 7.0 μm or less. If the thickness of the outer coating layers 5d and 6d exceeds 7.0 μm, the rigidity of the outer coating layers 5d and 6d becomes too strong, and even if the inner coating layers 5c and 6c undergo thermal decomposition, it may become difficult to remove the outer coating layers 5d and 6d. Furthermore, it is preferable that the thickness of the insulating coatings 5b and 6b, which is the sum of the thickness of the inner coating layers 5c and 6c and the outer coating layers 5d and 6d, exceeds 8.0 μm. For example, if the insulating coatings 5b and 6b are thin, pinholes may form in the insulating coatings 5b and 6b depending on the manufacturing conditions. Also, the insulating coatings 5b and 6b may wear down due to friction during use. In this case, the internal conductor wires 5a and 6a will be exposed, and the conductor wires 5a and 6a may corrode from that point.To prevent such corrosion, if the insulating coatings 5b and 6b are thin, it is necessary to form an additional insulating coating or the like on the outer periphery of the insulating coatings 5b and 6b.

[0040] When winding the above-mentioned conductor strands 5a and 6a around the core material 3, it is preferable to align them rather than twist them together. This is because aligning them results in a thinner diameter for the wire body 10 and a smoother surface. In addition to aligning and twisting, the conductor strands 5a and 6a can also be braided around the core material 3.

[0041] The insulating layer 7 may be formed by extrusion molding or the like, or an insulating layer 7 that has been pre-formed into a tube shape may be used. The method of forming the insulating layer 7 is not particularly limited. When the insulating layer 7 is formed by extrusion molding, the positions of the conductor wires 5a and 6a are fixed, so misalignment between the insulating layer 7 and the conductor wires 5a and 6a is unlikely to occur. As a result, friction and bending of the conductor wires 5a and 6a are prevented, and the bending resistance is improved, which is preferable. The material of the insulating layer 7 can be appropriately designed depending on the form of use and environment of the linear body, and various materials can be used, such as polyolefin resins, polyester resins, polyurethane resins, aromatic polyamide resins, aliphatic polyamide resins, vinyl chloride resins, modified noryl resins (polyphenylene oxide resins), nylon resins, polystyrene resins, fluororesins, synthetic rubbers, fluororubber, ethylene-based thermoplastic elastomers, urethane-based thermoplastic elastomers, styrene-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, etc. In particular, a polymer composition having flame retardancy is preferably used. A polymer composition having flame retardancy here refers to one with an oxygen index of 21 or higher in the flammability test according to JIS-K7201 (1999). Those with an oxygen index of 26 or higher are particularly preferred. To obtain such flame retardancy, flame retardants may be appropriately blended into the material constituting the insulating layer 7 described above. Examples of flame retardants include metal hydrates such as magnesium hydroxide and aluminum hydroxide, antimony oxide, melamine compounds, phosphorus compounds, chlorine-based flame retardants, and bromine-based flame retardants. These flame retardants may be appropriately surface-treated by known methods.

[0042] Furthermore, by forming this insulating layer 7 with a heat-sealing material, the linear body 10 can be heat-sealed to the substrate 11 by heating and pressurizing. In such cases, among the materials constituting the insulating layer 7 described above, an olefin resin with excellent adhesion to the substrate 11 is preferred. Examples of olefin resins include high-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, linear low-density polyethylene, polypropylene, polybutene, ethylene-α-olefin copolymer, and ethylene-unsaturated ester copolymer. Examples of ethylene-unsaturated ester copolymers include ethylene-vinyl acetate copolymer, ethylene-(meth)acrylate methyl copolymer, ethylene-(meth)acrylate ethyl copolymer, and ethylene-(meth)acrylate butyl copolymer, and these may be used individually or as a mixture of two or more. Here, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid. Any of these can be selected, but it is preferable that the material melts at a temperature below the decomposition start temperature or below the melting point of the material constituting the insulating coatings 5b and 6b described above. Furthermore, polyester thermoplastic elastomers are used as materials that exhibit excellent adhesion to the base material 11. Polyester thermoplastic elastomers include polyester-polyester type and polyester-polyether type, but the polyester-polyether type is preferred due to its superior adhesion. When heat-sealing the linear body 10 and the base material 11, the adhesive strength between the linear body 10 and the base material 11 is extremely important. If this adhesive strength is insufficient, the base material 11 and the linear body 10 may separate during use, resulting in unexpected bending of the linear body 10, increasing the likelihood of the conductor wires 5a and 6a breaking. If the conductor wires 5a and 6a break, the linear body, i.e., the heater wire, will no longer function, and there is a risk of sparking due to chattering. Additionally, if the operating temperature of the linear body 10 is high, it is preferable to use a polyamide thermoplastic elastomer. Of course, the insulating layer 7 materials described above may be a combination of multiple types, and various known additives such as flame retardants and anti-aging agents may be added.

[0043] The insulating layer 7 may be formed in multiple layers, not just one. For example, a layer of fluororesin may be formed on the outer circumference of the conductor wires 5a and 6a, and a layer of polyester thermoplastic elastomer may be formed on the outer circumference of the fluororesin as a heat-sealing material, with these two layers constituting the insulating layer 7. Of course, it may also consist of three or more layers. Furthermore, the insulating layer 7 is not limited to being formed continuously in the longitudinal direction. For example, it may be formed in a straight line or spiral line along the longitudinal direction of the linear body 10, in a dot pattern, or intermittently. In this case, it is preferable that the heat-sealing material is not continuous in the longitudinal direction of the linear body, because even if a part of the heat-sealing material ignites, the burning area will not spread. Also, if the volume of the heat-sealing material is sufficiently small, even if the heat-sealing material is a flammable material, the burning material will quickly disappear and the fire will be extinguished, and no drip (combustion droplets) will be generated. Therefore, it is preferable that the volume of the heat-sealing material be the minimum necessary to maintain adhesion with the base material 11.

[0044] Furthermore, in a flexibility test in which the linear body 10 obtained as described above is bent at 90-degree intervals with a radius of curvature six times its own diameter, it is preferable that the number of bends until at least one conductor strand breaks is 20,000 or more.

[0045] Furthermore, when processing the ends of the linear body 10, soldering may be performed as in the above embodiment, or other methods may be used. For example, by bringing a heat source at a predetermined temperature close to the exposed end of the heating wire 1, or by blowing hot air at a predetermined temperature, the inner layers 5c and 6c of the coating will decompose thermally, and the insulating coatings 5b and 6b (outer layers 5d and 6d) will shrink, exposing the ends of the conductor wires 5a and 6a. The predetermined temperature here refers to a temperature above the thermal decomposition temperature of the inner layers 5c and 6c of the coating.

[0046] As the base material 11, in addition to the nonwoven fabric shown in the above embodiment, various materials can be used, such as woven fabric, paper, aluminum foil, mica sheet, resin sheet, foamed resin sheet, rubber sheet, foamed rubber sheet, stretched porous body, etc. However, it is preferable to use a material that has flame retardancy that passes the combustion test for automotive interior layer materials, FMVSS-No.302. Here, FMVSS stands for Federal Motor Vehicle Safety Standard, which is the U.S. Federal Motor Vehicle Safety Standard, and No. 302 specifies the combustion test for automotive interior materials. Among these, nonwoven fabric is preferred in particular for car seat heater applications because it has a good texture and flexibility. Furthermore, even when using nonwoven fabric, in the above embodiment, a fiber having a core-sheath structure with low-melting-point polyester as the sheath component is used as the heat-fusible fiber constituting the nonwoven fabric, but other materials such as a fiber having a core-sheath structure with low-melting-point polypropylene as the sheath component, or a fiber having a core-sheath structure with polyethylene as the sheath component can also be considered. By using such heat-fusible fibers, the sheath portion of the heat-fusible fiber and the insulating layer 7 (heat-fusible layer) fuse together and become one, surrounding the core portion of the heat-fusible fiber. As a result, the adhesion between the linear body 10 and the nonwoven fabric becomes very strong. In addition, as for flame-retardant fibers, various flame-retardant fibers can be used in addition to the flame-retardant polyester mentioned above. Here, flame-retardant fibers refer to fibers that meet JIS-L1091 (1999). By using such flame-retardant fibers, the base material is given excellent flame retardancy.

[0047] The mixing ratio of heat-fusible fibers is preferably 5% or more, and preferably 20% or less. If the mixing ratio of heat-fusible fibers is less than 5%, sufficient adhesion cannot be obtained. Furthermore, if the mixing ratio of heat-fusible fibers exceeds 20%, the nonwoven fabric becomes stiff, which may cause discomfort to the person sitting on it, and conversely, the adhesion to the cord-type heater will decrease. In addition, the heat generated during heat fusion may cause the base material to shrink, making it impossible to obtain the dimensions intended in the design. The mixing ratio of flame-retardant fibers is 70% or more, and preferably 70% to 95%. If the mixing ratio of flame-retardant fibers is less than 70%, sufficient flame retardancy cannot be obtained. Furthermore, if the mixing ratio of flame-retardant fibers exceeds 95%, the mixing ratio of heat-fusible fibers will be relatively insufficient, and sufficient adhesion cannot be obtained. Furthermore, the combined percentage of heat-fusible fibers and flame-retardant fibers does not need to equal 100%, and other fibers may be mixed in as appropriate. Also, even if heat-fusible fibers are not mixed in, sufficient adhesion can be obtained by, for example, using materials of the same type for the heat-fusible portion and the fibers constituting the base material, so it is entirely possible that heat-fusible fibers may not be mixed in.

[0048] Furthermore, the size and thickness of the nonwoven fabric should be appropriately changed depending on the intended use, but its thickness (measured when dry) should preferably be around 0.6 mm to 1.4 mm. This is because using a nonwoven fabric of this thickness ensures that when the linear body and the nonwoven fabric are bonded and fixed by heating and pressurizing, the nonwoven fabric adheres well to 30% or more, preferably 50% or more, of the outer circumference of the linear body, thereby achieving a strong bond.

[0049] Among the above-mentioned base materials, those having voids are preferred, and in particular, it is preferable that the surface on which the linear body is arranged (hereinafter referred to as the "arrangement surface") has more voids than the surface on which the linear body is not arranged (hereinafter referred to as the "non-arrangement surface"). A state with many voids refers to, for example, in the case of fabrics such as woven fabrics and nonwoven fabrics, a state in which the basis weight, i.e., the fiber weight per unit volume, is small, and in the case of porous materials such as foamed resin sheets and foamed rubber sheets, a state in which the porosity is large. Specific embodiments of the base material according to the present invention include, for example, woven or nonwoven fabrics that have undergone calendering with varying degrees of strength on one side or both sides by adjusting the temperature and pressure, nonwoven fabrics that have been needle-punched from only one side, fabrics with pile formation or napping on one side, foamed resin sheets or foamed rubber sheets whose foaming is controlled so that the porosity slopes in the thickness direction, and materials with different amounts of voids bonded together. Furthermore, it is particularly preferable that the voids in the base material are continuous. This is because the molten heat-sealed layer penetrates into continuous voids, increasing the anchoring effect and improving adhesive strength. Examples of materials with continuous voids include fabrics such as woven or nonwoven fabrics, which are aggregates of fibers, and foamed resin sheets or foamed rubber sheets with continuous pores. It should be noted that non-adhered surfaces may not have voids.

[0050] Furthermore, when arranging the linear body 10 on the base material 11, the linear body 10 may be fixed to the base material 11 by means other than bonding and fixing by heat and pressure. For example, various methods are possible, such as a method in which the insulating layer 7 made of a heat-fusible material is melted and bonded by hot air, a method in which current is passed through the conductor strands 5a and 6a and the heat generated melts and bonds and fixes the insulating layer 7 made of a heat-fusible material, or a method in which the linear body 10 is sandwiched and fixed by a pair of base materials 11 while heating.

[0051] Furthermore, configurations that do not use heat-sealing materials are also conceivable. For example, the linear body 10 could be placed on the base material 11 by sewing, or the linear body 10 could be sandwiched and fixed between a pair of base materials 11. In such cases, it is conceivable that the insulating layer 7 would not be formed.

[0052] Furthermore, regarding the adhesive layer for fixing the planar unit 31 to the seat, it is preferable to form an adhesive layer consisting only of adhesive on a release sheet or the like, and then transfer the adhesive layer from the release sheet to the surface of the base material 11, considering the elasticity of the base material 11 and the maintenance of a good texture. In addition, it is preferable that this adhesive layer is flame-retardant, and preferably one that has flame retardancy such that it can pass the FMVSS-No.302 combustion test for automotive interior materials on its own. Examples include polymer acrylic adhesives. The adhesive layer may be formed on the surface of the base material to be installed or on the non-installation surface.

[0053] Furthermore, the planar unit 31 having the above configuration may be installed on the steering wheel 71 in the state shown in Figure 8. This steering wheel 71 consists of a wheel portion 72, a spoke portion 73, and a boss portion 74, and the planar unit 31 will be installed between the wheel core material 77 and the covering material 78 of the wheel portion 72.

[0054] Furthermore, the linear body 10 according to the present invention can have a capacitance detection function by using any arbitrary conductor strand as an electrode wire. By configuring at least two of the wound conductor strands as electrode wires capable of measuring the capacitance value between strands, it can be used as a two-electrode type capacitance sensor. For specific structures, refer to Patent No. 6851730 (Patent Document 8) by the said patent applicant, and other known capacitance detection mechanisms can also be used. With this configuration, the distance between strands between the two electrodes can be fixed to a constant value, making it possible to provide stable detection accuracy, and in addition, it has the effect of achieving both high heat generation due to the low resistance value design and contact determination by capacitance detection. In addition, it is also possible to use any arbitrary conductor strand as a temperature detection wire, and by using the structure of Patent No. 6771975 (Patent Document 9) by the said patent applicant in the present invention, a single linear body can combine a heating wire, a capacitance detection wire, and a temperature detection wire.

[0055] [Patent Document 8] Patent No. 6851730: Kurabe [Patent Document 9] Patent No. 6771975: Kurabe

[0056] As described above, the linear body 10 according to the present invention has conductive strands 5a and 6a wound in a multi-layered manner. By having an appropriate multi-layer structure, it is possible to reduce the resistance value of the conductive strands while maintaining an aesthetic appearance, that is, to improve the heat output of the heater wire. [Industrial applicability]

[0057] As detailed above, the present invention provides a linear body capable of increasing heat output. This linear body can be arranged in a predetermined shape, such as a meandering shape, on a base material such as aluminum foil, foamed resin, or nonwoven fabric to form a planar unit, which can be suitably used in electric blankets, electric carpets, car seat heaters, steering wheel heaters, heated toilet seats, heaters for anti-fog mirrors, anti-freeze heaters for cameras, heating and cooking appliances, etc. Furthermore, the linear body can also be used as a standalone unit, for example, by wrapping it around and adhering it to pipes or tanks, or by placing it inside pipes. Specific applications include, for example, anti-freeze heaters for piping and pipe drains in freezers, heat-retaining heaters for air conditioners and dehumidifiers, defrosting heaters for refrigerators and freezers, drying heaters, and floor heating heaters. Furthermore, for applications of the planar unit as exemplified above, such as electric blankets, electric carpets, car seat heaters, steering wheel heaters, heated toilet seats, anti-fog mirror heaters, heating appliances, and floor heating, the linear body of the present invention can also be directly attached to or wrapped around the object to be heated. [Explanation of Symbols]

[0058] 1. Heating wire 3 Core material 5a, 6a Conductor strands 5b, 6b insulating coating 5c, 6c Inner layer of coating 5d,6d Outer coating layer 7. Insulating layer (thermal fusion layer) 10 linear body 11 Base material 31 Planar Units 41 Vehicle seats 71 Steering Wheel

Claims

1. A linear body having multiple conductor strands and a core wire, The above multiple conductor strands are aligned and wound around the above core wire. The above winding is laminated and has an inner layer and an outer layer. The gap between the conductor strands in the inner layer is greater than 0.009 mm. The gap between the conductor strands of the inner layer is less than or equal to the wire diameter of the conductor strands of the inner layer. The gap between the conductor strands of the inner layer is less than or equal to the wire diameter of the conductor strands of the outer layer. linear body

2. The linear body according to claim 1, wherein the gap between the conductive strands of the outer layer is greater than 0.031 mm.

3. The linear body according to claim 1, wherein the conductor strands of the inner layer have a diameter 0.6 to 1.4 times that of the conductor strands of the outer layer.

4. A linear body according to any one of claims 1 to 3, wherein multiple conductive strands are insulated.

5. A linear body according to any one of claims 1 to 3, wherein the above inner layer and the above outer layer are adjacent to each other.

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