Electric wire, heater, and heater for car seat

Abstract

An electric wire (10) has: a conducting wire (20); an insulating layer (30) that is composed of solely first resin or of a first resin composition containing the first resin and covers the conducting wire (20); and a heat fusion layer (40) that is composed of solely second resin different from the first resin or a second resin composition containing the second resin and covers the insulating layer (30). The melting point of the second resin or the second resin composition is lower than the melting point of the first resin or the first resin composition by 20°C or more.

Description

Electric wire, heater, and heater for car seat

[0001] The present invention relates to 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) in which an insulating film is 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 in which a plurality of single wires are twisted together. 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 outside 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 molded 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] When fixing the cord-shaped heater described in Patent Document 1 to a base material, it is necessary to heat and press in a state where the cord-shaped heater is disposed on the base material. At this time, since the inner layer coating and the outer layer coating of the cord-shaped heater described in Patent Document 1 are fused and have low flexibility, it cannot be strongly bent. Thus, the cord-shaped heater described in Patent Document 1 has a problem of low flexibility.

[0006] The main object of the present invention is to provide an electric wire that can maintain flexibility even if it has a heat-fused layer. Another object of the present invention is to provide 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 comprising: a conductor; an insulating layer covering the conductor, which is composed of only a first resin or a first resin composition containing the first resin; and a heat-sealable layer covering the insulating layer, which is composed of only a second resin of a different type from the first resin or a second resin composition containing the second resin, wherein the melting point of the second resin or the second resin composition is 20°C or more lower than the melting point of the first resin or the first resin composition.

[0008] 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.

[0009] 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.

[0010] According to the present invention, it is possible to provide an electric wire that can maintain its flexibility even when it has a heat-sealed layer.

[0011] Figures 1A and 1B show the configuration of the electric wire. Figures 2A and 2B are diagrams illustrating the heat-sealed layer.

[0012] 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.

[0013] [Wire Structure] Figure 1A is a schematic cross-sectional view of a wire 10 according to one embodiment of the present invention, and Figure 1B is a schematic side view of the stranded wire 22 in the wire 10. Figure 2A is a diagram illustrating a heat-sealed layer composed of filamentous material, and Figure 2B is a diagram illustrating a tubular heat-sealed layer.

[0014] As shown in Figures 1A and 1B, the electric wire 10 has a conductor 20, an insulating layer 30, and a heat-sealing layer 40.

[0015] The conductor 20 may be a stranded wire 22 made by twisting together multiple strands 21, or it may be a single strand 21.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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 1B) 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.

[0020] 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.

[0021] As shown in Figure 1A, 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.

[0022] 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.

[0023] 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.

[0024] (Insulating layer) The insulating layer 30 is made of resin and is not particularly limited as long as it can insulate the conductor 20. 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.

[0025] 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.

[0026] 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.

[0027] (Heat-Sealing Layer) The heat-sealing layer 40 is made of resin and covers the insulating layer 30, and is heat-sealed to the substrate. That is, the heat-sealing layer 40 is located on the outermost layer of the electric wire 10. The heat-sealing layer 40 is composed of only the second resin, or a second resin composition containing the second resin. Examples of the second resin include nylon resins such as fusion-bondable nylon, urethane resins such as fusion-bondable urethane, olefin resins such as polypropylene and polyethylene, and polyester resins.

[0028] 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 appropriately surface-treated by known methods.

[0029] The first resin used in the insulating layer 30 and the second resin used in the heat-sealable layer 40 are different types of resins. Here, different types of resins include resins with different main chain structures, resins with different functional groups, and copolymers with different monomer units. In the example of the first resin described above, fluororesin, olefin resin, nylon resin, and vinyl resin are different types of resins, while ETFE, FEP, and PFA contained in fluororesin are similar resins. Similarly, in the example of the second resin described above, nylon resin, urethane resin, olefin resin, and polyester resin are different types of resins, while polypropylene and polyethylene contained in olefin resin are similar resins. In other words, a second resin of the same type as the resin used as the first resin is not used. Because the first resin and the second resin are different types of resins, even if the heat-sealable layer 40 is formed on the insulating layer 30, the insulating layer 30 and the heat-sealable layer 40 will not adhere to each other. Therefore, when the electric wire 10 is bent, the insulating layer 30 and the heat-sealed layer 40 can move relative to each other in the longitudinal direction of the electric wire 10, allowing the electric wire 10 to be bent appropriately.

[0030] Furthermore, the melting point of the second resin (second resin composition) used in the heat-sealable layer 40 is at least 20°C lower than the melting point of the first resin (first resin composition) used in the insulating layer 30. The melting point of the first resin (first resin composition) is in the range of 120 to 320°C, and the melting point of the second resin (second resin composition) is preferably in the range of 100 to 170°C. If the melting point of the first resin (first resin composition) is lower than the above range, it may deform when heat-sealed to the substrate. If the melting point of the first resin (first resin composition) is higher than the above range, it may deteriorate when the heat-sealable layer 40 is extruded. If the melting point of the second resin (second resin composition) is lower than the above range, it may melt at the temperature when using a heater, causing displacement. If the melting point of the second resin (second resin composition) is higher than the above range, the substrate may deteriorate when heat-sealed to the substrate. Therefore, it is preferable that the melting point of the second resin (second resin composition) used in the heat-sealable layer 40 is lower than the melting point of the first resin (first resin composition) used in the insulating layer 30, within a range of 220°C or less. By satisfying the above requirements, the insulating layer 30 will not melt when fixed to the substrate by heat fusion, and the insulating layer 30 and the heat-sealable layer 40 will not mix together.

[0031] The shape of the heat-sealable layer 40 may be made up of filamentous material (Figure 2B) or tubular material (Figure 2A). Here, the heat-sealable layer 40 is formed by winding a filamentous material around the surface of the insulating layer 30. Examples of filamentous material include fusible nylon yarn, fusible urethane yarn, and polyester yarn. The outer diameter of the filamentous material is not particularly limited. A single filamentous material may be used, or a twisted yarn made by twisting multiple filaments together may be used. The heat-sealable layer 40 may be a single layer or multiple layers. In this embodiment, a twisted yarn made by twisting multiple filaments together is wound around the insulating layer 30 to form a single layer. The filamentous material may cover the entire insulating layer 30 or only a part of it. Covering only a part means that there are gaps between the threads. In this embodiment, the filamentous material is wound so as to cover the entire insulating layer 30.

[0032] The heat-sealable layer 40 is arranged in a cylindrical shape so as to surround the insulating layer 30. In this embodiment, the cylindrical heat-sealable layer 40 is formed by extrusion molding.

[0033] The thickness of the heat-sealable layer 40, whether composed of filamentous material or tubular material, is not particularly limited as long as it can heat-seal the electric wire 10 to the base material when melted by heating. The thickness of the heat-sealable layer 40 is in the range of 0.05 to 0.50 mm in both cases.

[0034] 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.

[0035] (Effects) As described above, in the electric wire of this embodiment, the first resin and the second resin are different types of resins, and the melting point of the second resin is 20°C or more lower than the melting point of the first resin, resulting in good flexibility.

[0036] 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.

[0037] Example 1 1. Manufacturing of electric wire A cast rod of a Cu-based alloy containing 3% by mass of Ag and the remainder being Cu and unavoidable impurities was prepared. Next, the cast rod was cold-worked to make a wire. After heat-treating the wire, Cu-Ag alloy wire was manufactured by cold-working it to a thickness of 0.05 mm. The obtained Cu-Ag alloy wire was coated with varnish and baked to enamel-coate the Cu-Ag alloy wire, and 11 Cu-Ag alloy strands with a diameter of 0.06 mm were prepared. The 11 prepared strands were twisted together to obtain a stranded wire with a twist pitch of 5.0 mm. An insulating layer with a thickness of 0.1 mm was formed by extruding ETFE (first resin) around the obtained stranded wire, and a heat-sealed layer with a thickness of 0.2 mm was formed by extruding fusion nylon (second resin) to obtain electric wire 1. The outer diameter of electric wire 1 was 1.0 mm. Except for changing the first and second resins to the resins shown in the table, wires 2 to 30 were obtained in the same manner as wire 1.

[0038] Table 1 shows the first resin and its melting point, the second resin and its melting point, and the temperature difference between the melting points of the first and second resins.

[0039]

[0040] 2. Evaluation (Evaluation of Adhesion between Substrate and Heat-Fused Layer) Each wire was bonded to a polyester nonwoven fabric substrate with a bonding length of 25 cm, using a second resin at a melting point of +20 to 30°C and under pressure. The adhesive strength (N) of the substrate and heat-fused layer was evaluated using a 180-degree peel test, where the peeling direction was 180 degrees relative to the bonding surface. The substrate and each wire were held in a jig, and the strength was measured when peeled off at a constant speed (25 mm / min). Adhesion was evaluated according to the following criteria: Evaluation Criteria ○: The adhesive strength between the substrate and the wire was 1.5 N or higher. ×: The adhesive strength between the substrate and the wire was less than 1.5 N.

[0041] (Evaluation of Peelability of Insulation Layer and Heat Fusing Layer) Samples were prepared by cutting each wire adhered to the non-woven fabric to a length of 75 mm. A jig with a hole larger than the outer diameter of the insulation layer and smaller than the outer diameter of the heat fusing layer was prepared for the tensile testing machine. The non-woven fabric and the fusing layer on one side of 25 mm of each wire were peeled off. A wire with a part of the heat fusing layer peeled off was inserted into the hole of the jig and installed on the tensile testing machine. By pulling the jig side at a speed of 10 mm / sec, the adhesion strength between the insulation layer and the heat fusing layer was measured and used as an index for peelability. The peelability was evaluated according to the following criteria. Evaluation Criteria 〇: The adhesion strength between the insulation layer and the heat fusing layer was 30 N or less. ×: The adhesion strength between the insulation layer and the heat fusing layer exceeded 30 N.

[0042] (Evaluation of Flexibility) The flexibility of the wire was evaluated using a jig in which two plates were configured to be rotatable via a hinge. First, the angle between the two plates was opened to 180°, and the wire was fixed to the surface where the hinge was fixed. Next, the distance between the two plates was reduced until it became twice the outer diameter of the wire, and the wire was bent. Finally, the angle between the two plates was opened to 180° to return the bent wire to its original state. This series of operations was regarded as one time, and it was repeated until one or more of the strands of the wire broke, and the number of times when it broke was measured. The flexibility was evaluated according to the following criteria. Evaluation Criteria 〇: The number of bending times was 1000 or more. ×: The number of bending times was less than 1000.

[0043] (Comprehensive Evaluation) The comprehensive evaluation was evaluated according to the following criteria. ○: All evaluation results were "〇". ×: Any one of the evaluation results was "×".

[0044] Each evaluation result is shown in Table 2.

[0045]

[0046] As shown in Tables 1 and 2, for Wires 1-3, 5, 7-9, 12-15, 18, 19, 24, 25, 30, in which the first resin and the second resin are different resins and the melting point of the second resin is 20°C or more lower than the melting point of the first resin, all of the adhesiveness between the base material and the heat fusing layer, the peelability between the insulation layer and the heat fusing layer, and the flexibility were good.

[0047] On the other hand, for the electric wires 6, 20 - 22, 26 - 28 where the first resin and the second resin are of the same resin type, the peelability between the insulating layer and the heat - fusion layer and the flexibility were poor. This is presumably because the first resin and the second resin are of the same resin type, causing the insulating layer and the heat - fusion layer to adhere to each other. For the electric wires 4, 10, 11, 16, 17, 23, 29 where the first resin and the second resin are of different resin types, but the melting point of the second resin is not 20°C or more lower than the melting point of the first resin, the peelability between the insulating layer and the heat - fusion layer and the flexibility were poor. This is presumably because the melting point of the second resin is not 20°C or more lower than the melting point of the first resin, causing the insulating layer to melt.

[0048] Example 2 1. Manufacture of electric wire A heat - fusion layer was formed by winding a filament made of the second resin around the insulating layer. In this example, the entire insulating layer was wound so as to be covered with the filament, and the film thickness of the heat - fusion layer was set to 0.2 mm. Electric wires 31 - 60 were obtained in the same manner as electric wires 1 - 30, except for the configuration of the heat - fusion layer.

[0049] Table 3 shows the first resin and its melting point, the second resin and its melting point, and the temperature difference between the melting points of the first resin and the second resin.

[0050]

[0051] 2. Evaluation The evaluation of the adhesiveness between the base material and the heat - fusion layer, the evaluation of the peelability between the insulating layer and the heat - fusion layer, the evaluation of the flexibility, and the comprehensive evaluation were carried out in the same manner as in Example 1.

[0052] The results of each evaluation are shown in Table 4.

[0053]

[0054] As shown in Tables 3 and 4, for the electric wires 31 - 33, 35, 37 - 39, 42 - 45, 48, 49, 54, 55, 60 where the first resin and the second resin are of different resin types and the melting point of the second resin is 20°C or more lower than the melting point of the first resin, the adhesiveness between the base material and the heat - fusion layer, the peelability between the insulating layer and the heat - fusion layer, and the flexibility were all good.

[0055] On the other hand, in wires 36, 50-52, and 56-58, where the first and second resins were of the same type, the peelability of the insulating layer and heat-sealed layer, as well as the flexibility, were poor. This is thought to be because the insulating layer and heat-sealed layer adhered together due to the first and second resins being of the same type. In wires 34, 40, 41, 46, 47, 53, and 59, where the first and second resins were of different types, but the melting point of the second resin was not more than 20°C lower than the melting point of the first resin, the peelability of the insulating layer and heat-sealed layer, as well as the flexibility, were poor. This is thought to be because the insulating layer melted because the melting point of the second resin was not more than 20°C lower than the melting point of the first resin.

[0056] The electric wire of the present invention can be used, for example, in heaters or car seat heaters.

[0057] 10 Electric wire 20 Conductor 21 Stranded wire 22 Stranded wire 25 Conductor 26 Coating 30 Insulating layer 40 Heat-sealed layer

Claims

1. An electric wire comprising: a conductor; an insulating layer covering the conductor, composed solely of a first resin or a first resin composition containing the first resin; and a heat-sealable layer covering the insulating layer, composed solely of a second resin of a different type from the first resin or a second resin composition containing the second resin, wherein the melting point of the second resin or the second resin composition is 20°C or more lower than the melting point of the first resin or the first resin composition.

2. An electric wire according to claim 1, characterized in that the insulating layer and the heat-sealed layer are not bonded together.

3. An electric wire according to claim 1, characterized in that the heat-sealed layer is composed of filamentous material.

4. An electric wire according to claim 1, wherein the heat-sealed layer is a cylindrical body.

5. 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.

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

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

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

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