Electric wire, electric wire manufacturing method, heater, and heater for car seat

Abstract

An electric wire (10) is characterized by having a conductive wire (20), an insulating layer (30) that covers the conductive wire (20), and a heat-fusible yarn (40) that is wound on the insulating layer (30).

Description

Electric wire, method for manufacturing an electric wire, heater, and heater for car seat

[0007]

[0001] The present invention relates to an electric wire, a method for manufacturing an electric wire, a heater, and a heater for a car seat.

[0002] For seat heaters installed in automobiles, etc., an electric wire (cord-shaped heater) is used as a heat source. The electric wire is adhered and fixed to a base material such as a non-woven fabric, a resin sheet, or a foamed resin sheet by heating and pressing. The electric wire is a single wire (stranded wire) having an insulating layer (film) formed on the surface of a conductor such as a copper wire, a copper alloy wire, or a nickel alloy wire, or a stranded wire formed by twisting a plurality of single wires. When the electric wire is fused to the base material by heating and pressing in this way, it is necessary to form a heat-fused layer on the outside of the conductor (see, for example, Patent Document 1).

[0003] Patent Document 1 describes a cord-shaped heater having a conductor single wire, an insulating film covering the conductor single wire, an inner layer coating made of resin formed on the insulating film, and an outer layer coating made of resin covering the inner layer coating. Both the inner layer coating and the outer layer coating (heat-fused layer) are extrusion-molded, and the formed inner layer coating and outer layer coating are fused. The cord-shaped heater is fixed to the base material by heat fusion.

[0004] International Publication No. 2019 / 021970

[0005] In the cord-shaped heater described in Patent Document 1, since both the inner layer coating and the outer layer coating are formed by extrusion molding, the heat capacity is large and there is a concern that the insulating layer of the conductor single wire may be thermally deteriorated. Further, the cord-shaped heater described in Patent Document 1 has a problem that the manufacturing cost is high because it is necessary to use two extrusion machines to extrude both the inner layer coating and the outer layer coating.

[0006] The main object of the present invention is to provide an electric wire that can be heat-fused, suppresses thermal deterioration of the film during manufacturing, and can be manufactured at a low cost. Another object of the present invention is to provide a method for manufacturing the electric wire, a heater having the electric wire, and a heater for a car seat having the heater.

[0007] To solve the above problems, according to one aspect of the present invention, there is an electric wire characterized by comprising: a conductor; an insulating layer covering the conductor; and a heat-sealable yarn wound on the insulating layer.

[0008] To solve the above problems, according to one aspect of the present invention, a method for manufacturing an electric wire is provided, characterized by comprising the steps of: preparing a conductor; covering the conductor with an insulating layer; and winding a heat-fusible thread on the insulating layer.

[0009] To solve the above problems, according to one aspect of the present invention, a heater is provided that includes the electric wire of the present invention as a heating element.

[0010] To solve the above problems, according to one aspect of the present invention, a car seat heater is provided, characterized by having the heater of the present invention.

[0011] According to the present invention, it is possible to provide an electric wire that can be heat-sealed, suppresses thermal degradation of the coating during manufacturing, and can be manufactured at low cost.

[0012] Figures 1A and 1B show the configuration of an electric wire according to an embodiment of the present invention. Figure 2 is a schematic side view of a stranded wire. Figure 3 is a flowchart of the method for manufacturing an electric wire according to an embodiment of the present invention.

[0013] The following describes an electric wire, heater, and car seat heater according to one embodiment of the present invention. However, the electric wire, heater, and car seat heater of the present invention are not limited to the embodiments shown below. In this specification, the "~" indicating a numerical range includes both an upper and lower limit.

[0014] [Wire Structure] Figure 1A is a schematic cross-sectional view of a wire 10 according to one embodiment of the present invention, with a portion of the heat-fusible yarn removed, and Figure 1B is a schematic cross-sectional view of the wire 10 of line A-A shown in Figure 1A. Figure 2 is a schematic side view of the stranded wire 22.

[0015] As shown in Figures 1A and 1B, the electric wire 10 has a conductor 20, an insulating layer 30, and a heat-sealed thread 40. Here, the outer diameter R of the electric wire 10 refers to the maximum length of the portion where the heat-sealed thread 40 is located in a cross section perpendicular to the longitudinal direction of the electric wire 10 shown in Figure 1B.

[0016] The conductor 20 may be a stranded wire 22 made by twisting together multiple strands 21, or it may be a single strand 21.

[0017] Here, we will explain in detail the case where the conductor 20 is a stranded wire 22. When the outer diameter of the stranded wire 22 is X mm and the twist pitch of the stranded wire 22 is Y mm, it is preferable that Y / X is in the range of 10 to 100. When Y / X is 10 or less, the direction of extension of the strands 21 (direction of the spiral) is greatly inclined with respect to the longitudinal direction of the electric wire 10, resulting in a high degree of contact. On the other hand, when Y / X is 100 or more, the inclination of the direction of extension of the strands 21 becomes smaller, resulting in a low degree of contact.

[0018] Specifically, a Y / X ratio of 10 or more prevents the degree of adhesion between the stranded wire 22 and the insulating layer 30 in the electric wire 10 from becoming too large, thereby suppressing damage to the stranded wire 22 during terminal processing. In other words, a Y / X ratio of 10 or more prevents the contact area between the stranded wire 22 and the insulating layer 30 per unit length of the electric wire 10 from becoming too large, thereby suppressing the degree of adhesion. From this viewpoint, a Y / X ratio of 15 or more is preferable.

[0019] On the other hand, if Y / X is 100 or less, the contact load between the strands 21 in the stranded wire 22 does not become too small, which prevents the stranded wire 22 from coming off the insulating layer 30 during terminal processing. In other words, if Y / X is 100 or less, the contact area between the stranded wire 22 and the insulating layer 30 per unit length of the electric wire 10 does not become too small, and the degree of adhesion can be maintained. From this viewpoint, Y / X is preferably 80 or less, and more preferably 50 or less. The contact load between the stranded wire 22 and the insulating layer 30 is preferably in the range of 0.5 to 20.0 N. If the contact load is 0.5 N or less, the stranded wire 22 will come off the insulating layer 30 during terminal processing. Also, if the contact load is 20 N or more, when peeling off the insulating layer 30, a strong force is required due to the high adhesion, and there is a risk that the wire stripper will come into contact with the stranded wire 22 and damage it.

[0020] The twist pitch Y is the axial length of the stranded wire 22 when one of the multiple strands 21 that are twisted into a spiral shape (the strand 21 with a diagonal line in Figure 2) is traced along this strand 21 and the strand 21 completes one revolution (360° rotation) around the central axis (spiral axis) of the stranded wire 22.

[0021] The number of strands 21 in the stranded wire 22 is not particularly limited. The number of strands 21 in the stranded wire 22 is, for example, about 5 to 40. The twist pitch Y and outer diameter X of the stranded wire 22 preferably satisfy the above Y / X. The twist pitch Y of the stranded wire 22 is, for example, about 2 to 60 mm. On the other hand, the outer diameter X of the stranded wire 22 is, for example, about 0.1 to 0.6 mm.

[0022] As shown in Figure 1B, the strand 21 has a conductor 25 and a coating 26 covering the conductor 25. In this embodiment, the strand 21 is an enameled wire, the conductor 25 is the conductor of the enameled wire, and the coating 26 is an enameled coating. The outer diameter of the strand 21 in the stranded wire 22 is, for example, about 0.03 to 0.08 mm. The outer diameter of the strand 21 in the single wire is, for example, about 0.03 to 0.60 mm.

[0023] The conductor 25 is not particularly limited as long as it is electrically conductive. Examples of materials for the conductor 25 include metals and metal alloys. Examples of metals and metal alloys include Cu, Ag, and Cu alloys such as Cu-Ag alloys. In this embodiment, the material of the conductor 25 is a Cu-Ag alloy, and the wire 21 is a Cu-Ag alloy wire with a coating 26 formed on the surface of the Cu-Ag alloy wire. The Cu and Ag content of the Cu-Ag alloy is not particularly limited. In this embodiment, the Cu-Ag alloy contains, for example, 1 to 15% by mass of Ag, with the remainder being Cu and unavoidable impurities.

[0024] If the wire strand 21 is an enameled wire, the enameled coating may be an insulating coating formed by applying and baking a known varnish onto the conductor 25. Examples of varnishes that constitute the insulating coating include polyvinyl acetal (e.g., polyvinyl formal or polyvinyl butyral), polyurethane, nylon, polyester, epoxy resin, polyesterimide, polyamide, polyimide, and polyamideimide. From the viewpoint of facilitating soldering, polyurethane is preferred as the varnish that constitutes the insulating coating.

[0025] (Insulating layer) The insulating layer 30 is made of resin and is not particularly limited as long as it can insulate the conductor 20. Preferably, the insulating layer 30 is made of only the first resin or a first resin composition containing the first resin. Examples of the first resin include fluororesins such as ethylene tetrafluoroethylene (ETFE), perfluoroethylene-propylene copolymer (FEP), and perfluoroalkoxyalkane (PFA), olefin resins such as polypropylene and polyethylene, and vinyl resins such as nylon and polyvinyl chloride.

[0026] The first resin composition may contain additives as long as they do not impair the above-mentioned functions. Examples of additives include flame retardants. 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.

[0027] The thickness of the insulating layer 30 is not particularly limited as long as it can perform the desired insulating function. When the electric wire 10 is used as a heating wire, the thickness of the insulating layer 30 is preferably such that it can easily conduct heat. The thickness of the insulating layer 30 may be, for example, about 0.05 to 1.00 mm. The insulating layer 30 can be formed by extruding a material that forms the insulating layer 30 around the conductor 20.

[0028] (Heat-fusible yarn) The heat-fusible yarn 40 is made of resin and is wound around the insulating layer 30 and heat-fused to the base material. That is, the heat-fusible yarn 40 is arranged in the outermost layer of the electric wire 10. The heat-fusible yarn 40 is composed of only the second resin or a second resin composition containing the second resin. Examples of the second resin include nylon resin such as fusible nylon, urethane resin such as fusible urethane, olefin resin such as polypropylene and polyethylene, and polyester resin.

[0029] The second resin composition may contain additives as long as they do not impair the above-mentioned functions. Examples of additives include flame retardants. 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 surface-treated as appropriate by known methods. The first resin and the second resin may be the same resin or different resins.

[0030] The outer diameter of the heat-fusible yarn 40 is not particularly limited. Also, if the cross-section of the heat-fusible yarn 40 is not circular, the outer diameter is the area equivalent diameter. The heat-fusible yarn 40 may be used as a single strand, or a twisted yarn made by twisting multiple strands together may be used. Also, the heat-fusible yarn 40 may be wound so as not to overlap, or it may be wound in overlapping directions. In this embodiment, a twisted yarn made by twisting multiple strands together is wound around the insulating layer 30 so as not to overlap. The heat-fusible yarn 40 may be wound on the insulating layer 30 without any gaps, or with gaps between it and the other strands. In this embodiment, the heat-fusible yarn 40 is wound around the entire insulating layer 30 with gaps between it and the other strands. The heat-fusible yarn 40 is wound around the insulating layer 30 at room temperature after it has been extruded. As a result, the heat capacity of the electric wire 10 does not increase, and therefore the coating 26 does not deteriorate due to heat.

[0031] The thickness of the heat-fusible yarn 40 when it is wrapped around the base material is not particularly limited, as long as the electric wire 10 can be heat-fused to the base material when the heat-fusible yarn 40 melts due to heating. The thickness of the heat-fusible yarn 40 when it is wrapped around the base material is, for example, in the range of 0.05 to 0.50 mm.

[0032] Such a wire 10 can be used as a heating element. When the wire 10 is used as a heating element, it can be used as a heat source for a heater. A wire 10 that can be used as a heat source can be used in a car seat heater. When the wire 10 is used in a car seat heater, the wire 10 is heat-fused to a base material. Examples of base materials include polymer foams such as foamed resin sheets and foamed rubber sheets, and fabrics such as nonwoven fabrics and woven fabrics. Examples of base material materials include resin materials and rubber materials such as polyurethane resin, chloroprene rubber, silicone resin, silicone rubber, nitrile rubber, diene rubber, natural rubber, polyethylene resin, and polypropylene resin, as well as thermoplastic elastomers. When the wire 10 is used in a car seat heater, the heat-fused yarn 40 does not have adhesive properties until heated, resulting in excellent handling. In addition, in car seat heaters, it is necessary to reduce discomfort when sitting in the seat by reducing the diameter of the heater wire. As in this embodiment, by using the heat-sealable yarn 40, it is possible to suppress the increase in the outer diameter of the electric wire 10, thereby reducing discomfort when sitting in the seat.

[0033] (Method of manufacturing electric wires) Next, the method of manufacturing electric wires will be described. Figure 3 is a flowchart of the method of manufacturing electric wires according to an embodiment of the present invention.

[0034] As shown in Figure 3, the method for manufacturing the electric wire 10 includes the steps of preparing the conductor 20 (S110), covering the conductor 20 with an insulating layer 30 (S120), and winding the heat-sealable yarn 40 around the insulating layer 30 (S130).

[0035] In the step of preparing the conductor 20 (S110), the conductor 20 may be prepared by twisting together multiple strands 21, each having a conductor 25 covered with a film 26, using a stranding machine, or a single strand 21 may be prepared as the conductor 20.

[0036] In the step of covering with an insulating layer 30 (S120), the surface of the conductor 20 is covered with an insulating layer 30. Specifically, the insulating layer 30 is formed by extruding the first resin or first resin composition onto the conductor 20.

[0037] In the process of winding the heat-fusible yarn 40 (S130), the heat-fusible yarn 40, made of the second resin or second resin composition, is wound around the conductor 20 on which the insulating layer 30 has been formed. For example, at room temperature, the conductor 20 with the insulating layer formed and the heat-fusible yarn 40 can be set in a stranding machine and twisted together in the same way as when manufacturing a normal stranded wire. The stranding machine can be the same one used to manufacture the stranded wire 22. The heat-fusible yarn 40 may be wound around the insulating layer 30 without any gaps, or it may be wound with gaps. The heat-fusible yarn 40 is wound so that the thickness of the heat-fusible yarn 40 after winding is in the range of 0.05 to 0.50 mm. At this time, since the heat-fusible yarn 40 is wound at room temperature, the coating 26 is not damaged. In this way, when winding the heat-fusible yarn 40, the stranding machine can be reused, and there is no need to prepare two extruders as in the conventional method, so manufacturing costs can be reduced.

[0038] (Effects) As described above, in the electric wire of this embodiment, since a heat-sealed layer is not formed by extrusion molding, thermal degradation of the coating can be suppressed. In addition, the thickness of the heat-sealed yarn 40 can be adjusted by varying the number of heat-sealed yarns.

[0039] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited in any way by these examples, and the embodiments can be modified without departing from the spirit of the invention.

[0040] 1. Manufacture of Electric Wire A cast rod of a Cu-based alloy containing 3% by mass of Ag and the balance being Cu and inevitable impurities was prepared. Then, the cast rod was cold-worked into a wire. After heat-treating the wire, a Cu-Ag alloy wire was manufactured by cold-working it to 0.05 mm. A polyurethane was applied and baked onto the obtained Cu-Ag alloy wire to enamel-coat the Cu-Ag alloy wire, and a Cu-Ag alloy bare wire with a diameter of 0.06 mm was prepared. Eleven prepared bare wires were twisted together so that the twist pitch was 5.0 mm to obtain a stranded wire (conductive wire). An ETFE (first resin) was extrusion-molded around the obtained stranded wire to form an insulating layer so that the outer diameter became 0.7 mm. Next, a nylon thread (second resin) was wound around the entire insulating layer so that the thickness became 0.2 mm (outer diameter became 1.1 mm) to obtain Electric Wire 1. Electric Wires 2 to 18 were obtained in the same manner as Electric Wire 1, except that the resin types were changed to the resins shown in the table.

[0041] After obtaining a stranded wire (conductive wire) in the same manner as Electric Wire 1, nylon (the first resin) was extrusion-molded to form an insulating layer so that the outer diameter became 0.7 mm. Next, nylon was extrusion-molded to cover the entire insulating layer so that the thickness became 0.2 mm (outer diameter became 1.1 mm) to obtain Electric Wire 19. Electric Wires 20 to 60 were obtained in the same manner as Electric Wire 19, except that the first resin and the second resin were changed to the resins shown in the table.

[0042] The configurations of the insulating layer and the heat fusion layer are shown in Tables 1 and 2.

[0043]

[0044]

[0045] 2. Evaluation (Evaluation of Thermal Degradation of Bare Wire) The evaluation of the thermal degradation of the bare wire was carried out by measuring the softening temperature of the film by thermomechanical analysis (TMA). The measurement conditions were as follows. Sample shape: One bare wire Temperature rising rate: 10 °C / min Temperature range: Room temperature to 210 °C Atmosphere: Air Detection method: Penetration method Load: 1 g (constant) Number of measurements: Only the first measurement for each bare wire Also, the thermal degradation of the bare wire was evaluated according to the following criteria. 〇: The softening temperature was within the range of 120 to 130 °C. ×: The softening temperature was less than 120 °C or more than 130 °C.

[0046] (Evaluation of Adhesion between Base Material and Heat-Fusion Layer) For a polyester non-woven fabric as the base material, each electric wire was adhered by pressing at a temperature of the melting point of the second resin + 20°C so that the adhesion length was 25 cm. The adhesion strength (N) between the base material and the heat-fusion layer was evaluated by a 180° peel test in which the peeling direction was 180° with respect to the adhesion surface. The base material and each electric wire were grasped with jigs respectively, and the strength when peeling at a constant speed (25 mm / min) was measured. The adhesion was evaluated according to the following criteria. Evaluation Criteria 〇: The adhesion strength between the base material and the electric wire was 1.5 N or more. ×: The adhesion strength between the base material and the electric wire was less than 1.5 N.

[0047] (Evaluation of Flexibility) The flexibility was evaluated according to the following criteria. 〇: It could be bent flexibly and had excellent wiring property. ×: It was difficult to bend the electric wire and had poor workability during wiring.

[0048] (Overall Evaluation) The overall evaluation was made according to the following criteria. ○: All evaluation results were "〇". ×: Any one of the evaluation results was "×".

[0049] Each evaluation result is shown in Tables 3 and 4.

[0050]

[0051]

[0052] As shown in Tables 3 and 4, for the electric wires 1 to 18 with the heat-fusion yarn wound around the insulating layer, the thermal degradation of the strand wires, the adhesion between the base material and the heat-fusion layer, and the flexibility were all good.

[0053] On the other hand, for the electric wires 19 to 60 with the heat-fusion layer formed by extrusion molding, the thermal degradation of the strand wires and the flexibility were poor. This is considered to be because the heat capacity of the electric wire increased due to the formation of the heat-fusion layer by extrusion molding, resulting in thermal degradation of the film.

[0054] The electric wire of the present invention can be used, for example, in a heater or a heater for a car seat.

[0055] 10 Electric wire 20 Conductor wire 21 Strand wire 22 Twisted wire 25 Conductor 26 Film 30 Insulating layer 40 Heat-fusion yarn

Claims

1. An electric wire characterized by comprising: a conductor; an insulating layer covering the conductor; and a heat-sealable yarn wound on the insulating layer.

2. An electric wire according to claim 1, characterized in that the conductor is a Cu-Ag alloy wire.

3. An electric wire according to claim 1, characterized in that the conductor is a stranded wire formed by twisting together a plurality of Cu-Ag alloy wires.

4. An electric wire according to claim 1, characterized in that it is used as an electric heating wire.

5. A method for manufacturing an electric wire, comprising the steps of: preparing a conductor; covering the conductor with an insulating layer; and winding a heat-sealable thread onto the insulating layer.

6. A heater characterized by including the electric wire described in claim 1 as a heating element.

7. A car seat heater characterized by having the heater described in claim 6.

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