Linear body and planar unit

Abstract

To provide a linear body having excellent productivity and a planar unit using the same.SOLUTION: A linear body 11 includes a conductor wire 15a and an insulating coating 19 formed around the conductor wire 15a, at least the outermost layer of the insulating coating 19 is made of polybutylene terephthalate resin. The linear body 11 functions as a heater wire. The linear body 11 functions as a sensor wire. In a planar unit, the linear body is disposed on a substrate, and the substrate and the linear body are connected by a sewing thread.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a linear body that can be used as a heater wire that can be suitably used in electric blankets, electric carpets, car seat heaters, steering heaters, etc., and as a sensor wire that can be suitably used for temperature detection and contact detection of car seats and steering wheels, and to a planar unit in which the linear body is disposed on a substrate and can be used as a heater unit or sensor unit, and particularly to one with excellent productivity. [Background technology]

[0002] It has been proposed to mount a heater unit on the wheel of a steering wheel in order to warm the driver's hands in cold weather. A steering wheel is made up of a wheel, a spoke, and a boss. The wheel is made up of a wheel core material in which a metal core is covered with urethane resin or the like, and a covering material made of synthetic resin, textile products, leather, or the like. The heater unit is installed between the wheel core material and the covering material, and is connected to a lead wire passing through the spoke and boss to receive power. It has also been proposed to place a seat heater between the seat cover and the seat pad in a vehicle seat in order to warm the driver in cold weather.

[0003] Known heater units installed in steering wheels include those in which a heater wire is arranged in a predetermined pattern on a substrate, as shown in Patent Documents 1 to 4. Here, various types of foamed resin sheets, foamed rubber sheets, rubber sheets, nonwoven fabrics, woven fabrics, etc. are disclosed as substrates. In addition, Patent Documents 5 to 8, etc. are cited as related techniques.

[0004] Examples of the sensor unit include those that function as a capacitance sensor or a temperature sensor. Capacitive sensors are used in touch panels and seating detectors, and in particular, so-called two-electrode capacitance sensors are widely used in various applications due to their excellent detection sensitivity. This is because the capacitance value between two electrodes that are insulated in a close proximity changes when a human body approaches the two electrodes, and this change in capacitance is detected. Such a technology is being considered, for example, as a steering wheel grip detection. Examples of sensor units using linear capacitance sensors include Patent Document 9. Temperature sensors are known that are used as temperature detection means for heating appliances such as electric carpets and electric blankets. This has a structure in which a sensor wire is wound around a central core wire and the outer periphery is covered with a sheath, and temperature detection is performed by detecting the change in resistance value of the sensor wire due to the temperature. This sensor wire is used, for example, in the vicinity of a heat source such as a heater wire to detect the temperature of the heater wire, or in a meandering shape to detect the temperature as a surface. An example of a sensor unit using a linear temperature sensor is disclosed in Patent Document 10. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4202071: Kurabe [Patent Document 2] International Publication WO2014 / 104000: Toyoda Gosei, Kurabe [Patent Document 3] Patent No. 6468701: Kurabe [Patent Document 4] Patent No. 6760941: Kurabe [Patent Document 5] Patent No. 3991750: Matsushita Electric Industrial Co., Ltd. [Patent Document 6] Patent No. 671727: Kurabe [Patent Document 7] Patent No. 671728: Kurabe [Patent Document 8] Patent No. 6829577: Kurabe [Patent Document 9] Patent No. 6851730: Kurabe [Patent Document 10] Patent No. 5562678: Kurabe DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0006] An insulating coating is formed on the outer periphery of the linear body to reliably insulate the inner conductor from the outside. This insulating coating is required to have not only high insulation properties, but also heat resistance sufficient to withstand heat when used as a heater wire, flexibility to be arranged in a meandering shape or the like on a substrate, mechanical strength to withstand friction and bending, and flame retardancy to prevent the spread of fire in the event of a fire.

[0007] Here, as a method for disposing a linear body such as a heater wire or a sensor wire on a substrate, there are known a method for forming a heat-sealing layer on the outer periphery of the linear body, and then heating and pressurizing the linear body and the substrate to fuse the linear body to the substrate, and a method for sewing the linear body to the substrate with a sewing thread. In particular, when using a method for sewing the linear body to the substrate with a sewing thread, the insulating coating is required to have a slipperiness on the surface in addition to the above characteristics. If the insulating coating surface has low slipperiness, the sewing thread may get caught on the insulating coating surface, causing problems such as thread breakage and abnormal sewing position. The occurrence of such problems will significantly reduce the productivity of planar units (heater units and sensor units).

[0008] The present invention has been made to solve such problems in the prior art, and its object is to provide a linear body that has excellent productivity when manufacturing a planar unit, and a planar unit using the same. [Means for solving the problem]

[0009] In order to achieve the above object, a linear body according to the present invention has a conductor wire and an insulating coating formed on the outer periphery of the conductor wire, and at least the outermost layer of the insulating coating is made of polybutylene terephthalate resin. The linear body according to the present invention may also function as a heater wire. The linear body according to the present invention may also function as a sensor line. Furthermore, the planar unit according to the present invention has the linear body described above disposed on a base material, and the base material and the linear body are connected by a sewing thread. Effect of the Invention

[0010] According to the linear body of the present invention, the surface of the insulating coating is made of polybutylene terephthalate resin, which has good slipperiness, so that the sewing thread does not get caught on the insulating coating when sewing, preventing thread breakage and abnormal sewing position, resulting in excellent productivity when manufacturing the surface unit. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a plan view showing the configuration of one surface of a planar unit according to the present invention. [Diagram 2] 3A to 3C are enlarged cross-sectional views each showing a schematic diagram of a main portion of a planar unit according to an embodiment of the present invention during manufacturing. [Diagram 3] FIG. 2 is a partially cutaway side view showing an example of a linear body used in the present invention. [Figure 4] FIG. 2 is a partially cutaway side view showing an example of a linear body used in the present invention. [Diagram 5] FIG. 2 is a partially cutaway side view showing an example of a linear body used in the present invention. [Figure 6] FIG. 2 is a partially cutaway side view showing an example of a linear body used in the present invention. [Figure 7] FIG. 2 is a partially cutaway side view showing an example of a linear body used in the present invention. [Figure 8] FIG. 2 is a partially cutaway side view showing an example of a linear body used in the present invention. [Figure 9] FIG. 2 is a partially cutaway side view showing an example of a linear body used in the present invention. [Figure 10] 1 is a partially cutaway perspective view showing a state in which a planar unit according to the present invention is embedded in a steering wheel. [Figure 11] 1 is a partially cutaway perspective view showing a state in which a planar unit according to the present invention is embedded in a vehicle seat. BEST MODE FOR CARRYING OUT THEINVENTION

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

[0013] First, an embodiment will be described with reference to FIG. 1. The configuration of the linear body, i.e., the heater wire 11 in this embodiment will be described. The heater wire 11 in this embodiment has a configuration as shown in FIG. 3 and FIG. 4. First, the core wire 13 is formed of an aromatic polyamide fiber bundle having an outer diameter of about 0.1 mm. Five conductor wires 15a, which are hard tin-containing copper alloy wires having an element diameter of 0.05 mm, are wound in a spiral shape at a pitch of about 0.5 mm around the outer periphery of the core wire 13. As shown in FIG. 3 and FIG. 4, an insulating coating 15b is formed around the conductor wires 15a. The insulating coating 15b is formed of an inner layer 15c made of polyurethane resin and an outer layer 15d made of polyamideimide resin. The inner layer 15c of the insulating coating 15b is formed to a thickness of 3.5 μm by applying polyurethane varnish around the conductor wires 15a and drying it. Next, the outer layer 15d is formed by applying polyamideimide varnish to the outer periphery of the inner layer 15c and drying it to form a layer with a thickness of 3 μm. An insulating coating 19 is formed on the outer periphery of the core wire 13 around which the conductor wire 15a is wound. The insulating coating 19 is formed by extrusion coating polybutylene terephthalate resin to a thickness of 0.04 mm. The finished outer diameter of the heater wire 11 described above is 0.3 mm. The core wire 13 is effective in terms of increasing flexibility and tensile strength. It is also possible to align or twist a plurality of conductor wires together without using the core wire 13.

[0014] Next, the structure of the substrate 31 on which the heater wire 11 having the above-mentioned structure is disposed will be described. The substrate 31 in the embodiment 1 has an apparent density of 40 kg / m 3 The base material 31 is made of a polyurethane foam having a hardness of 220N (based on JIS K7222) and a thickness of 8 mm. Such a base material 31 is cut into a desired shape by a known method such as die cutting.

[0015] Next, a configuration for disposing the heater wire 11 in a predetermined pattern on one surface of the base material 31 will be described. The base material 31 is placed on a movable table, and the heater wire 11 is placed on a heater wire supplying machine installed in association with a sewing machine. The heater wire 11 is supplied immediately in front of a needle bar unit of the sewing machine, and in synchronization with this, the movable table moves in a predetermined pattern, and at the same time, the heater wire 11 is sewn to the base material 31 by the sewing machine. In this way, the heater wire 11 is disposed in a meandering shape on the base material 31. FIG. 2 is an enlarged cross-sectional view showing a main part of the planar unit 1 in a state in which the heater wire 11 is sewn to the surface of the base material 31. The sewing thread is composed of an upper thread 33 and a lower thread 35, and the upper thread 33 wraps around the heater wire 11 almost entirely and is entangled with the lower thread 35 on the back side to be sewn to the base material 31. The upper thread 33 is a 120 denier polyester filament thread, and the lower thread 35 is a 120 denier polyester filament thread. The stitching pitch is 2 mm in the straight portion of the meandering shape and 1 mm in the curved portion of the meandering shape.

[0016] By carrying out the above operations, a planar unit 1 as shown in Fig. 1 can be obtained. The heater wire 11 is fastened and fixed to the base material 31 by the sewing threads (upper thread 33 and lower thread 35), so the planar unit 1 is generally flat. In addition, since the polybutylene terephthalate resin used as the insulating coating 19 has good slipperiness, the upper thread 33 does not get caught on the insulating coating 19, and no thread breakage or abnormal sewing position occurred.

[0017] In the planar unit 1 obtained as described above, both ends of the heater wire 11 are pulled out and connected to lead wires 37, and the heater wire 11, a temperature control device 39, and a connector (not shown) are connected by the lead wires 37. The temperature control device 39 is disposed on the heater wire 11, and controls the temperature of the planar unit by the heat generated by the heater wire 11. The temperature control device 39 is then connected to the vehicle's electrical system (not shown) via the connector described above.

[0018] The planar unit 1 having the above configuration is installed on a steering wheel 71 in the state shown in Fig. 10. This steering wheel 71 is made up of a wheel portion 72, spoke portions 73, and a boss portion 74, and the planar unit 1 is installed between a wheel core material 77 and a covering material 78 of the wheel portion 72.

[0019] An adhesive layer (not shown) is formed on the substrate 31 for bonding the planar unit 1 to the covering material 78 of the steering wheel, or the planar unit 1 to the wheel core material 77 of the steering wheel. The adhesive layer is preferably formed by forming an adhesive layer consisting of only an adhesive on a release sheet in advance, and transferring the adhesive layer from the release sheet to the surface of the substrate 31. This prevents the adhesive from penetrating into the substrate 31, and results in an adhesive layer being formed only on the surface of the substrate 31.

[0020] When installing the planar unit 1 on the steering wheel, any one of the following manufacturing methods 1 to 4 was used. (Method 1) In manufacturing method 1, the planar unit 1 and the covering material 78 are bonded together, and at that time, the surface side on which the heater wire 11 is disposed is bonded to the covering material 78. Thereafter, the covering material 78 to which the planar unit 1 is bonded is used to cover the wheel core material 77. (Method 2) In manufacturing method 2, the planar unit 1 and the covering material 78 are bonded together, and at that time, the surface side on which the heater wire 11 is not disposed is bonded to the covering material 78. Thereafter, the covering material 78 to which the planar unit 1 is bonded is used to cover the wheel core material 77. (Method 3) In manufacturing method 3, the planar unit 1 and the wheel core material 77 are bonded together, with the surface side on which the heater wire 11 is disposed being bonded to the wheel core material 77. Thereafter, the wheel core material 77 to which the planar unit 1 is bonded is covered with a covering material 78. (Method 4) In manufacturing method 4, the planar unit 1 and the wheel core material 77 are bonded together, and at that time, the surface side on which the heater wire 11 is not disposed is bonded to the wheel core material 77. Thereafter, the wheel core material 77 to which the planar unit 1 is bonded is covered with a covering material 78.

[0021] The present invention is not limited to the above embodiment. The linear body may be a sensor wire, or a plurality of linear bodies may be used, one of which is a heater wire and the other is a sensor wire. If a heater wire is used, the planar unit 31 becomes a heater unit, and if a sensor wire is used, the planar unit 31 becomes a sensor unit. The sensor wire can be used as a capacitance sensor or other sensors such as a temperature sensor. As a type of temperature sensor, the conductor wire can be soldered to form an abnormal temperature detection unit. In terms of detecting radio waves, the linear body can be used as an antenna wire to form an antenna unit. Also, a single linear body can be used that includes both a conductor wire that performs a heater function and a conductor wire that performs a sensor function.

[0022] It is also possible to use the linear body as a shield wire. When using a shield wire together with a heater wire or a sensor wire, the shield wire is used to prevent the influence of electromagnetic waves from the heater wire on the outside, or to prevent the influence of electromagnetic waves from the outside on the sensor wire. Generally, one or both ends of the shield wire are connected to ground.

[0023] As the heater wire 11, various cord-shaped heaters known in the art can be used, and for example, the following configuration can be used. 1. As in the above embodiment shown in FIG. 3, first, a plurality of conductor wires 15a covered with insulating coating 15b are twisted or pulled together and wound around core wire 13, and then an insulating coating 19 is applied to the outer periphery of the conductor wire 15a to form heater wire 11. 2. As shown in FIG. 5, the heater wire 11 is formed by twisting together a plurality of conductor wires 15a covered with an insulating coating 15b, and further covering the outer periphery of the stranded conductor wires with an insulating coating 19. 3. As shown in FIG. 6, the heater wire 11 is formed by arranging a plurality of conductor wires 15a covered with an insulating coating 15b, and further covering the outer periphery of the conductor wires with an insulating coating 19. 4. As shown in FIG. 7, the heater wire 11 is formed by alternately arranging conductor wires 15a covered with an insulating coating 15b and conductor wires 15a not covered with an insulating coating 15b. 5. As shown in FIG. 8, a heater wire 11 is formed by arranging the conductor wires 15a covered with the insulating coating 15b in a parallel manner with the number of the conductor wires 15a covered with the insulating coating 15b being increased from that shown in FIG. 6. As shown in FIG. 9, a heater wire 11 having an insulating layer 17 formed thereon in addition to an insulating coating 19. Various other configurations are possible for the heater wire 11. The heater wire 11 can also be formed by twisting together the core wire 13 and the conductor wires 15a. Unless otherwise noted, anything that can be applied to the heater wire 11 can also be applied to a sensor wire or a shielded wire.

[0024] Examples of the core wire 13 include inorganic fibers such as glass fibers, polyester fibers such as polyethylene terephthalate, aliphatic polyamide fibers, aromatic polyamide fibers, fully aromatic polyester fibers, and other organic fibers, such as monofilaments, multifilaments, spans, or fiber materials thereof, or fibers having a configuration in which the organic polymer material constituting the fiber material is used as a core material and is covered with a thermoplastic organic polymer material. In addition, when a core wire 13 having heat shrinkability and heat meltability is used, if the conductor wire 15a is broken and abnormally heated, the core wire 13 melts and is cut and shrinks. When the core wire 13 shrinks, the conductor wire 15a wound around the core wire 13 follows the movement of the core wire 13, so that the ends of the broken conductor wire 15a are separated from each other. Therefore, the ends of the broken conductor wire 15a do not repeatedly come into contact and separate from each other. In addition, the ends of the broken conductor wire 15a do not come into contact with each other with a small contact area such as a point contact. This prevents abnormal heat generation. Furthermore, when the conductor wires 15a are insulated by the insulating coating 15b, the core wire 13 does not need to be made of an insulating material. For example, a stainless steel wire or a titanium alloy wire can be used as the core wire 13. However, since there is a possibility that the conductor wires 15a may break, it is better that the core wire 13 is made of an insulating material.

[0025] As the conductor wire 15a, a conventionally known wire can be used, for example, a copper wire, a copper alloy wire, a nickel wire, an iron wire, an aluminum wire, a nickel-chromium alloy wire, an iron-chromium alloy wire, etc., and examples of the copper alloy wire include a tin-copper alloy wire, a copper-nickel alloy wire, and a silver-containing copper alloy wire in which a copper solid solution and a copper-silver eutectic are in the form of a fiber. Among these, it is preferable to use a copper wire or a copper alloy wire from the viewpoint of the balance between cost and characteristics. These copper wires or copper alloy wires are soft and hard, and from the viewpoint of bending resistance, hard wires are particularly preferable over soft wires. In addition, hard copper wires and hard copper alloy wires are wires in which individual metal crystal grains are elongated in the processing direction by cold processing such as wire drawing, resulting in a fibrous structure. When such hard copper wires or hard copper alloy wires are heated at a temperature higher than the recrystallization temperature, the processing strain generated in the metal crystals is eliminated, and crystal nuclei that become the base points of new metal crystals begin to appear. These crystal nuclei develop, and recrystallization occurs, which replaces the old crystal grains, and the crystal grains grow. A soft copper wire or soft copper alloy wire is a wire in which the crystal grains grow. This soft copper wire or soft copper alloy wire has a higher elongation and electrical resistance than a hard copper wire or hard copper alloy wire, but has a lower tensile strength, so that the bending resistance is lower than that of a hard copper wire or hard copper alloy wire. In this way, since a hard copper wire or hard copper alloy wire becomes a soft copper wire or soft copper alloy wire with low bending resistance by heat treatment, it is preferable to perform processing with as little heat history as possible. In addition, the hard copper wire is defined in JIS-C3101 (1994), and the soft copper wire is defined in JIS-C3102 (1984). The soft copper wire is defined as one with an elongation of 15% or more when the outer diameter is 0.10 to 0.26 mm, 20% or more when the outer diameter is 0.29 to 0.70 mm, 25% or more when the outer diameter is 0.80 to 1.8 mm, and 30% or more when the outer diameter is 2.0 to 7.0 mm. The copper wire also includes one that is tin-plated. The tin-plated hard copper wire is defined in JIS-C3151 (1994), and the tin-plated soft copper wire is defined in JIS-C3152 (1984). Various cross-sectional shapes of the conductor wire 15a can be used, and are not limited to the commonly used circular cross-sectional shape, and a so-called rectangular wire may be used.

[0026] When the linear body is a temperature sensor wire, the conductor wire 15a is preferably made of a material whose resistance value changes greatly with temperature. Examples include various metal wires such as copper wire, copper alloy wire, nickel wire, iron wire, aluminum wire, nickel-chromium alloy wire, copper-nickel alloy, and iron-chromium alloy, carbon fiber wire, and conductive resin wire. Among these, those having a positive characteristic temperature coefficient are preferable. Nickel wire and platinum wire, which have a particularly large coefficient, can be preferably used. If the conductor wire has a positive characteristic temperature coefficient, the resistance value increases as the temperature rises, so that if the resistance value increases, it is determined that the temperature is abnormal, and the control method is to stop the flow of electricity. Therefore, in the unlikely event that the conductor wire 15a breaks, the resistance value becomes ∞, and the flow of electricity is stopped in the same way as when an abnormal temperature occurs. This is a very reliable method when viewed as a safety device.

[0027] When winding the conductor wire 15a around the core wire 13, among the above-mentioned materials for the conductor wire 15a, those that have a small amount of spring back when wound are preferred. For example, a silver-containing copper alloy wire in which copper solid solution and copper-silver eutectic are fibrous has excellent tensile strength and excellent tensile strength and bending strength, but is prone to spring back when wound. Therefore, when winding the conductor wire 15a around the core wire 13, the conductor wire 15a is likely to float or break due to excessive winding tension, and it is also likely to develop a twist tendency after processing, which is not preferred. In particular, when the conductor wire 15a is covered with an insulating coating 15b, the restoring force of the insulating coating 15b is also added. Therefore, it is important to select a conductor wire 15a with a small restoring rate to cover the restoring force of the insulating coating 15b.

[0028] The insulating coating 15b covering the conductor wire 15a may be formed of two layers, an inner layer 15c and an outer layer 15d, as in the above embodiment, or may be formed of three or more layers, or may be a single layer. In the case of a multiple layer structure, it is preferable that the thermal decomposition temperature of the material constituting the inner layer is lower than the lower of the melting point and the thermal decomposition temperature of the material constituting the outer layer. Here, the inner layer is a layer formed on the conductor wire 15a. The outer layer may be any layer that is located outside the inner layer, and therefore it is possible to form another outer layer outside the outer layer, or to form another intermediate layer between the inner layer and the outer layer.

[0029] Examples of the material of the insulating coating 15b include various materials such as polyurethane resin, polyamide resin, polyimide resin, polyamideimide resin, polyesterimide resin, nylon resin, polyesternylon resin, polyethylene resin, polystyrene resin, polypropylene resin, polyester resin, polybenzimidazole resin, vinyl chloride resin, fluororesin, and silicone resin. These materials may be used in combination of a plurality of types, or may be mixed with various known additives such as flame retardants and antiaging agents. Materials are combined from among these resins to make a material whose thermal decomposition temperature of the material constituting the inner layer is lower than the lower of the melting point or thermal decomposition temperature of the material constituting the outer layer. The material of the inner layer may be selected from polyurethane resin, vinyl chloride resin, polyacetal resin, polystyrene resin, polypropylene resin, polyester resin such as polymethyl methacrylate and polyethylene terephthalate, polyvinyl alcohol, and the like. In particular, it is preferable that the material of the inner layer is a thermosetting resin, and the material of the outer layer is a thermosetting resin. Here, the thermosetting resin also includes a crosslinkable material. From the viewpoint of heat generation characteristics as a heater wire and ease of terminal processing such as soldering, it is preferable that the material of the inner layer is polyurethane resin or polyester resin, and the material of the outer layer is any one of polyimide resin, polyamide-imide resin, and silicone resin. It is particularly preferable that the material of the inner layer is polyurethane resin, and the material of the outer layer is polyamide-imide resin. This polyurethane resin may be one that has been modified or blended in various ways, such as imide-containing polyurethane.

[0030] The thickness of the insulating coating 15b is preferably 3 to 30% of the diameter of the conductor wires 15a. If the thickness is less than 3%, sufficient voltage resistance characteristics cannot be obtained, and there is a possibility that there is no point in individually coating the conductor wires 15a. If the thickness is more than 30%, it becomes difficult to remove the insulating coating 15b when crimping the connection terminal, and the heater wire becomes unnecessarily thick.

[0031] When the conductor wires 15a are wound around the core wire 13 by drawing or twisting them together, it is preferable to draw them together rather than twisting them together. This is because the heater wire has a smaller diameter and a smoother surface. In addition to drawing or twisting them together, it is also possible to braid the conductor wires 15a around the core wire 13.

[0032] The linear body 11 according to the present invention may have an insulating coating 19 formed around the conductor wire 15a (see FIG. 9, for example). This insulating coating 19 insulates other components from electricity even if the conductor wire 15a is broken, and also insulates against high-temperature heat generation if a spark occurs. The insulating coating 19 may be formed by extrusion molding or the like, or may be covered with an insulating coating 19 previously formed into a tube shape, and there is no particular limitation on the method of formation. Forming the insulating coating 19 by extrusion molding is preferable because it fixes the position of the conductor wire 15a, preventing friction and bending of the conductor wire 15a due to positional deviation, thereby improving bending resistance. The material constituting the insulating coating 19 may be appropriately designed depending on the use form and environment of the heater wire, and may be, for example, polyolefin resin, polyester resin, polyurethane resin, aromatic polyamide resin, aliphatic polyamide resin, vinyl chloride resin, modified noryl resin (polyphenylene oxide resin), nylon resin, polystyrene resin, fluororesin, synthetic rubber, fluororubber, ethylene-based thermoplastic elastomer, urethane-based thermoplastic elastomer, styrene-based thermoplastic elastomer, polyester-based thermoplastic elastomer, and the like. In particular, a polymer composition having flame retardancy is preferably used. The polymer composition having flame retardancy here refers to a polymer composition having an oxygen index of 21 or more in the flammability test according to JIS-K7201 (1999). A polymer composition having an oxygen index of 26 or more is particularly preferred. In order to obtain such flame retardancy, a flame retardant or the like may be appropriately mixed into the material constituting the insulating coating 19 described above.

[0033] However, in the linear body 11 of the present invention, at least the outermost layer of the insulating coating 19 is made of polybutylene terephthalate resin. Polybutylene terephthalate resin is a polyester resin obtained by polycondensation of terephthalic acid (TPA) and 1,4-butanediol (1,4-BG). This improves the slipperiness of the surface of the insulating coating 19 in the linear body 11, prevents thread breakage and abnormal sewing positions, and increases productivity in the production of planar units. Of course, only the outermost layer may be made of polybutylene terephthalate resin, and there may be a layer made of another material as described above on the inside. For example, it is possible to use an insulating coating 19 made of an inner layer made of a polyester thermoplastic elastomer and an outer layer made of polybutylene terephthalate resin. The insulating coating 19 may also contain various additives, such as metal hydrates such as magnesium hydroxide and aluminum hydroxide, antimony oxide, melamine compounds, polyphosphorus compounds, phosphinate-based flame retardants, chlorine-based flame retardants, bromine-based flame retardants, and other flame retardants, antioxidants, antioxidants, fillers, lubricants, pigments, etc. These additives may be appropriately surface-treated by known methods.

[0034] Furthermore, it is preferable that the linear body 11 obtained as described above can be bent 20,000 times or more before at least one of the conductor wires breaks in a bending test in which the linear body 11 is bent at 90 degrees each time with a curvature radius six times its own diameter.

[0035] The substrate 31 is not limited to foamed polyurethane resin, and may be various polymer foams such as foamed resin sheets and foamed rubber sheets made of other materials. In particular, those having voids and excellent elasticity are preferable, and those with adjusted hardness so that the unevenness of the heater wire does not appear on the surface are preferable. In addition, methods for adjusting the hardness include adjusting the foaming rate, making the state of the bubbles closed or open, and using a material with a hardness according to the purpose. Materials may be selected from various resins, rubbers, thermoplastic elastomers, such as polyurethane resin, chloroprene rubber, silicone resin, silicone rubber, neoprene rubber, diene rubber, nitrile rubber, natural rubber, polyethylene resin, polypropylene resin, vinyl chloride resin, and ethylene-vinyl acetate copolymer. Other materials that can be used as the substrate 31 include, for example, nonwoven fabric, woven fabric, paper, aluminum foil, mica plate, resin sheet, and stretched porous body. As the substrate 31, a flame-retardant one is preferable, and a mixture of flame-retardant fibers and flame retardants is preferably used. Furthermore, a plurality of base materials 31 may be laminated, and in this case, the respective base materials 31 may be made of different materials or have different porosities.

[0036] As for the sewing thread, various known thread materials can be used. For example, inorganic fibers such as glass fibers, polyester fibers such as polyethylene terephthalate, aliphatic polyamide fibers, aromatic polyamide fibers, fully aromatic polyester fibers, polyethylene fibers, polypropylene fibers, polyvinyl chloride fibers, polylactic acid fibers, fluororesin fibers, and other organic fibers, such as monofilaments, multifilaments, and spun fibers, or fiber materials thereof, or fibers having a structure in which an organic polymer material constituting the fiber materials is used as a core material and a thermoplastic organic polymer material is coated on the circumference, can be mentioned. There is also no particular restriction on the sewing method. When sewing with a sewing machine, the upper thread 33 and the lower thread 35 may be made of different materials or the same material. As for the sewing pitch of the sewing thread, the smaller the sewing pitch, the higher the fixing strength, but on the other hand, the production speed decreases, so sewing may be performed with the minimum sewing pitch that can maintain the pattern shape of the linear body. The sewing pitch may also be changed depending on the location. When linear bodies are arranged in a pattern such as a meandering shape, it is possible to make the stitching pitch small only in the meandering curved portions so as to prevent the meandering shape from becoming distorted.

[0037] Furthermore, when arranging the linear body 11 on the base material 31, it is possible to combine other modes of fixing the heater wire 11 to the base material 31 instead of sewing with sewing thread. For example, it is possible to combine a mode in which the heater wire 11 is heated by passing electricity through it to a temperature higher than that in normal use, and the insulating coating 19 is melted by the heat to be bonded and fixed to the base material 31, a mode in which the conductor wire 15a is heated by induction heating, and the insulating coating 19 is melted by the heat to be bonded and fixed to the base material 31, a mode in which the insulating coating 19 is melted by hot air to be bonded and fixed, a mode in which the insulating coating 19 is sandwiched and fixed between a pair of base materials 31 while being heated, a mode in which the insulating coating 19 is fused to the base material 11 by heating and pressurizing, and the like. For example, it is possible that after a linear body 11 is arranged and fixed to the base material 31, another linear body 11 is further arranged and fixed to the base material 31, the arrangement in the front process may be sewn with sewing thread and the arrangement in the back process may be in another manner, or the arrangement in the front process may be in another manner and the arrangement in the back process may be sewn with sewing thread.

[0038] In addition, when multiple linear bodies are arranged, the positional relationship between them can be selected in various ways depending on the purpose. When multiple linear bodies are all heater wires, for example, one heater wire may be arranged in a pattern that provides excellent quick heating at start-up, and the other heater wire may be arranged in a pattern that provides excellent uniform heating at temperature equilibrium. In this case, it is preferable to reduce the overlapping portion of the multiple heater wires as much as possible. This is because the portion becomes thicker due to the diameter of the two linear bodies, and the two heater wires are located in close proximity to each other, which may result in overheating. On the other hand, when one linear body is a heater wire and the other linear body is a sensor wire for detecting temperature, it is preferable to arrange the heater wire and the sensor wire so that they overlap in the same pattern. This is because the detection wire for detecting temperature is located closest to the heating wire, allowing for more direct temperature detection. However, if there is a portion where the heater wire and the sensor wire overlap, there is a risk that the heater wire and the sensor wire will be short-circuited at that portion due to an external force. Therefore, it is preferable to configure the heater wire pattern and the sensor wire pattern not to overlap.

[0039] The adhesive layer may be, for example, an adhesive layer made of a polymeric acrylic adhesive and not using a tape substrate, an adhesive layer formed on both sides of a polypropylene film, or an adhesive layer formed on both sides of a nonwoven or woven fabric. If the adhesive layer alone has flame retardancy that passes the combustion test for automobile interior materials FMVSS No. 302, it is preferable because it improves the flame retardancy of the sheet unit. In addition, it is preferable that the adhesive layer is made of only an adhesive so as not to impair the stretchability of the sheet unit.

[0040] The planar unit according to the present invention can be arranged so that other planar units are overlapped. For example, it is conceivable to create a planar unit in which a heater wire and a shield wire are used as the multiple linear bodies, and then arrange a planar unit in which only a sensor wire is disposed on the shield wire side of this planar unit. In this way, the shield wire is present between the heater wire and the sensor wire, so that the electromagnetic waves from the heater wire are blocked by the shield wire and can be prevented from affecting the sensor wire.

[0041] The planar unit 1 according to the present invention can be used for various purposes other than the steering wheel shown in FIG. 10. For example, the planar unit 1 having the above configuration can be embedded and disposed in a vehicle seat 81 in the state shown in FIG. 11. The planar unit 1 in FIG. 11 is attached to an upholstery cover 83 or a seat pad 85, and disposed between the upholstery cover 83 and the seat pad 85. Here, the planar unit 1 is a heater unit using a heater wire as a linear body, and is used as a seat heating device. It is also conceivable that the linear body is used as a sensor unit using a capacitance sensor wire to detect the seating state. [Industrial Applicability]

[0042] The planar unit according to the present invention can be used in steering wheels and seats for automobiles, ships, various transport vehicles, various agricultural vehicles, various heavy machinery for civil engineering and construction, and can be suitably used as a heater unit for warming the steering wheel and the seat, as a temperature sensor unit for detecting the temperature of the steering wheel and the seat, or as a capacitance sensor unit for detecting the temperature of the steering wheel and the seat. The planar unit according to the present invention can be used for other purposes in addition to steering wheels and seats. For example, it can be applied to electric blankets, electric carpets, heated toilet seats, heaters for anti-fog mirrors, heating cookware, heaters for floor heating, heaters for clothing, various planar temperature detectors, capacitance detectors, etc. Also, as a linear body, it can be applied as a heater wire to various heating appliances and heating devices, and can be used as a sensor wire to various detection devices, etc. [Explanation of symbols]

[0043] 1 Planar unit 11 Linear body (heater wire) 13 Core Wire 15a Conductor wire 15b Insulation coating 19 Insulation coating 31 Base material 33 Upper thread (sewing thread) 35 Lower thread (sewing thread) 71 Steering Wheel 77 Wheel core material 78 Covering material 81 Vehicle seats 83 Skin cover 85 Seat Pad

Claims

1. The wire has a conductor wire and an insulating coating formed on the outer periphery of the conductor wire, The linear member, at least the outermost layer of the insulating coating is made of polybutylene terephthalate resin.

2. 2. The linear body according to claim 1, which functions as a heater wire.

3. The linear body according to claim 1 , which functions as a sensor line.

4. 4. A planar unit comprising the linear member according to claim 1, disposed on a base material, said base material and said linear member being connected by a sewing thread.

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