JP7660413B2 - Wiring sheet - Google Patents

Description

The present invention relates to a wiring sheet.

A sheet-like conductive member (hereinafter also referred to as a "conductive sheet") having a pseudo-sheet structure in which a plurality of conductive linear elements are arranged at intervals may be useful as a component for a variety of articles, such as a heating element for a heating device, a heat-generating textile material, or a protective film for a display (shatter-resistant film).
As an example of a sheet used as a heating element, Patent Document 1 describes a conductive sheet having a pseudo-sheet structure in which a plurality of linear elements extending in one direction are arranged at intervals. A pair of electrodes is provided on both ends of the linear elements, thereby obtaining a wiring sheet that can be used as a heating element.

International Publication No. 2017/086395

Metal foil or silver paste is usually used as the electrodes in wiring sheets. However, from the viewpoint of flexibility of the electrode part of the wiring sheet, the use of metal wire instead of metal foil or silver paste is being considered. On the other hand, when metal wire is used as the electrode, the resistance value of the electrode becomes relatively large. As a result, the difference with the resistance value of the linear body, which is the heat generating part, becomes small, and the resistance value of the electrode, which should be negligible, becomes not negligible. As a result, it has been found that when a current is passed through the wiring sheet to generate heat, temperature unevenness may occur.

The object of the present invention is to provide a wiring sheet that can suppress temperature unevenness.

According to one aspect of the present invention, there is provided a wiring sheet comprising a pseudo sheet structure in which a plurality of conductive linear bodies are arranged at intervals, and a pair of electrodes in direct contact with the conductive linear bodies, the electrodes each comprising a metal wire provided with a power supply portion, and the electrodes each comprising a metal wire located inward of the metal wire provided with the power supply portion when viewed from above the wiring sheet.

In the wiring sheet according to one aspect of the present invention, the metal wire is preferably gold plated.

In the wiring sheet according to one embodiment of the present invention, it is preferable that the distance between adjacent metal wires constituting the electrode is 0.5 mm or more and 15 mm or less.

In the wiring sheet according to one embodiment of the present invention, it is preferable that the distance between the outermost metal wire and the innermost metal wire constituting the electrode is 3 mm or more and 30 mm or less.

In the wiring sheet according to one aspect of the present invention, it is preferable that the metal wires constituting the pair of electrodes are line-symmetrical when viewed from above the wiring sheet.

In a wiring sheet according to one embodiment of the present invention, it is preferable that the metal wire constituting the electrode has a structure in which, in a plan view of the wiring sheet, it starts from one end of the pseudo sheet structure and folds back when it reaches the opposite end of the pseudo sheet structure.

According to one aspect of the present invention, a wiring sheet that can suppress temperature unevenness can be provided.

1 is a schematic diagram showing a wiring sheet according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the II-II section of FIG. FIG. 4 is a schematic diagram showing a wiring sheet according to a second embodiment of the present invention. FIG. 4 is a schematic diagram showing a wiring sheet according to a third embodiment of the present invention. FIG. 2 is a schematic diagram showing a sheet heater obtained in Comparative Example 1.

[First embodiment]
Hereinafter, the present invention will be described with reference to the drawings, taking an embodiment as an example. The present invention is not limited to the contents of the embodiment. In the drawings, some parts are illustrated enlarged or reduced in size for ease of explanation.

(Wiring sheet)
As shown in Figures 1 and 2, the wiring sheet 100 according to this embodiment includes a substrate 1, a pseudo sheet structure 2, a resin layer 3, and a pair of electrodes 4. Specifically, the wiring sheet 100 includes the resin layer 3 laminated on the substrate 1, and the pseudo sheet structure 2 laminated on the resin layer 3. The pseudo sheet structure 2 includes a plurality of conductive linear bodies 21 arranged at intervals. Each of the pair of electrodes 4 includes a metal wire 41 provided with a power supply portion 5.

In this embodiment, it is necessary that electrode 4 includes metal wire 41 on the inside of metal wire 41 on which power supply portion 5 is provided, when wiring sheet 100 is viewed in plan.
Here, "inside metal wire 41 on which power supply portion 5 is provided" refers to the opposite side of end portion of conductive linear object 21, which is regarded as the outside.

The present inventors surmise that the reason that temperature unevenness can be suppressed by providing metal wire 41 on the inner side of metal wire 41 on which power supply portion 5 is provided is as follows.
That is, if the electrode 4 is only one metal wire 41, the difference between the resistance value of the conductive linear body 21, which is the heat generating portion, and the resistance value of the electrode 4 becomes small, and the resistance value of the electrode 4, which should be negligible under normal circumstances, becomes non-negligible. As a result, when a current is passed through the wiring sheet 100 to generate heat, temperature unevenness may occur. The reason for this is that the conductive linear body 21 located far from the power supply unit 5 is greatly influenced by the resistance of the electrode 4 up to this conductive linear body 21. The inventors infer that, therefore, when a current is passed through the wiring sheet 100 to generate heat, the current flowing through this conductive linear body 21 becomes relatively small, and the temperature becomes lower than that of the other conductive linear bodies 21.
In contrast, if another metal wire 41 is provided inside the metal wire 41 on which the power supply unit 5 is provided, a current also flows through this other metal wire 41, which results in a lower resistance value of the electrode 4. The inventors speculate that in this way, temperature unevenness can be suppressed.

(Substrate)
The substrate 1 can directly or indirectly support the pseudo sheet structure 2. Examples of the substrate 1 include a synthetic resin film, paper, metal foil, nonwoven fabric, cloth, and glass film. The substrate 1 is preferably an elastic substrate. If the substrate 1 is an elastic substrate, the elasticity of the wiring sheet 100 can be ensured even when the pseudo sheet structure 2 is provided on the substrate 1.
As the stretchable substrate, a synthetic resin film, a nonwoven fabric, a cloth, or the like can be used.
Examples of synthetic resin films include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polyethylene naphthalate films, polybutylene terephthalate films, polyurethane films, ethylene vinyl acetate copolymer films, ionomer resin films, ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)acrylic acid ester copolymer films, polystyrene films, polycarbonate films, and polyimide films. Other examples of stretchable substrates include crosslinked films and laminated films of these.
Examples of nonwoven fabrics include spunbond nonwoven fabrics, needle punch nonwoven fabrics, melt blown nonwoven fabrics, and spunlace nonwoven fabrics. Examples of cloth include woven fabrics and knitted fabrics. The paper, nonwoven fabric, and cloth as the stretchable substrate are not limited to these.
The thickness of the elastic substrate is not particularly limited. The thickness of the elastic substrate is preferably 10 μm or more and 10 mm or less, more preferably 15 μm or more and 3 mm or less, and even more preferably 50 μm or more and 1.5 mm or less.

(Pseudo seat structure)
The pseudo sheet structure 2 has a structure in which a plurality of conductive linear bodies 21 are arranged at intervals from one another. That is, the pseudo sheet structure 2 is a structure in which a plurality of conductive linear bodies 21 are arranged at intervals from one another to form a flat or curved surface. The conductive linear bodies 21 extend in one direction and have a straight or wavy shape in a planar view of the wiring sheet 100. The pseudo sheet structure 2 has a structure in which a plurality of conductive linear bodies 21 are arranged in a direction perpendicular to the axial direction of the conductive linear bodies 21.
The conductive linear body 21 preferably has a wave shape in a plan view of the wiring sheet 100. Examples of the wave shape include a sine wave, a rectangular wave, a triangular wave, and a sawtooth wave. If the pseudo sheet structure 2 has such a structure, breakage of the conductive linear body 21 can be suppressed when the wiring sheet 100 is stretched in the axial direction of the conductive linear body 21.

The volume resistivity of the conductive linear body 21 is preferably 1.0×10 ⁻⁹ Ω·m or more and 1.0×10 ⁻³ Ω·m or less, and more preferably 1.0×10 ⁻⁸ Ω·m or more and 1.0×10 ⁻⁴ Ω·m or less. When the volume resistivity of the conductive linear body 21 is in the above range, the surface resistance of the pseudo sheet structure 2 is likely to be reduced.
The volume resistivity of the conductive linear body 21 is measured as follows: Silver paste is applied to both ends of the conductive linear body 21, and the resistance is measured at a portion 40 mm from each end to determine the resistance value of the conductive linear body 21. The volume resistivity of the conductive linear body 21 is then calculated by multiplying the resistance value by the cross-sectional area (unit: ^m2 ) of the conductive linear body 21 and dividing the obtained value by the measured length (0.04 m).

The cross-sectional shape of the conductive linear body 21 is not particularly limited and may be polygonal, flat, elliptical, circular, or the like. From the standpoint of compatibility with the resin layer 3, an elliptical or circular shape is preferable.
When the cross section of the conductive linear member 21 is circular, the thickness (diameter) D (see FIG. 2 ) of the conductive linear member 21 is preferably 5 μm or more and 75 μm or less. From the viewpoints of suppressing an increase in sheet resistance and improving heat generation efficiency and dielectric breakdown resistance characteristics when the wiring sheet 100 is used as a heating element, the diameter D of the conductive linear member 21 is more preferably 8 μm or more and 60 μm or less, and further preferably 12 μm or more and 40 μm or less.
When the cross section of the conductive linear body 21 is elliptical, it is preferable that the major axis is in the same range as the diameter D described above.

The diameter D of the conductive linear body 21 is determined by observing the conductive linear body 21 of the pseudo sheet structure 2 using a digital microscope, measuring the diameter of the conductive linear body 21 at five randomly selected points, and averaging the measured values.

The distance L between the conductive linear members 21 (see FIG. 2) is preferably 0.3 mm or more and 50 mm or less, more preferably 0.5 mm or more and 30 mm or less, and even more preferably 0.8 mm or more and 20 mm or less.
If the spacing between the conductive linear bodies 21 is within the above range, the conductive linear bodies are relatively densely packed, thereby improving the functionality of the wiring sheet 100, such as maintaining a low resistance of the pseudo sheet structure and making the distribution of temperature rise uniform when the wiring sheet 100 is used as a heating element.

The distance L between the conductive linear members 21 is measured by observing the conductive linear members 21 of the pseudo sheet structure 2 using a digital microscope and measuring the distance between two adjacent conductive linear members 21.
The interval between two adjacent conductive linear bodies 21 is the length along the direction in which the conductive linear bodies 21 are arranged, and is the length between opposing portions of the two conductive linear bodies 21 (see FIG. 2). When the conductive linear bodies 21 are arranged at uneven intervals, the interval L is the average value of the intervals between all adjacent conductive linear bodies 21.

The conductive linear body 21 is not particularly limited, but may be a linear body including a metal wire (hereinafter also referred to as a "metal wire linear body"). Metal wires have high thermal conductivity, high electrical conductivity, high handling properties, and versatility, so when a metal wire linear body is used as the conductive linear body 21, the resistance value of the pseudo sheet structure 2 is reduced while light transmittance is easily improved. Furthermore, when the wiring sheet 100 (pseudo sheet structure 2) is used as a heating body, rapid heat generation is easily achieved. Furthermore, as described above, a linear body having a small diameter is easily obtained.
In addition, examples of the conductive linear body 21 include a linear body containing a carbon nanotube and a linear body in which a conductive coating is applied to a thread, in addition to a metal wire linear body.

The metal wire linear body may be a linear body made of a single metal wire, or may be a linear body made of a plurality of twisted metal wires.
Examples of the metal wire include wires containing metals such as copper, aluminum, tungsten, iron, molybdenum, nickel, titanium, silver, and gold, or alloys containing two or more metals (e.g., steels such as stainless steel and carbon steel, brass, phosphor bronze, zirconium-copper alloys, beryllium copper, iron-nickel, nichrome, nickel-titanium, Kanthal, Hastelloy, and rhenium-tungsten). The metal wire may be plated with gold, tin, zinc, silver, nickel, chromium, nickel-chromium alloys, or solder, or may be coated with a carbon material or polymer described below. In particular, wires containing one or more metals selected from tungsten and molybdenum and alloys containing them are preferable from the viewpoint of forming a conductive linear body 21 that is thin, has high strength, and has a low volume resistivity.
The metal wire may be a metal wire coated with a carbon material. When the metal wire is coated with a carbon material, the metallic luster is reduced, and the presence of the metal wire can be easily made less noticeable. In addition, when the metal wire is coated with a carbon material, metal corrosion is also suppressed.
Examples of the carbon material that may be used to coat the metal wire include amorphous carbon (e.g., carbon black, activated carbon, hard carbon, soft carbon, mesoporous carbon, and carbon fiber), graphite, fullerene, graphene, and carbon nanotubes.

A linear body containing carbon nanotubes can be obtained, for example, by drawing carbon nanotubes into a sheet shape from the end of a carbon nanotube forest (a growth body in which multiple carbon nanotubes are grown on a substrate so as to be oriented perpendicular to the substrate, and sometimes referred to as an "array"), bundling the drawn carbon nanotube sheets, and twisting the bundle of carbon nanotubes. In such a manufacturing method, if no twist is applied during twisting, a ribbon-shaped carbon nanotube linear body is obtained, and if twist is applied, a thread-shaped linear body is obtained. A ribbon-shaped carbon nanotube linear body is a linear body in which the carbon nanotubes do not have a twisted structure. In addition, a carbon nanotube linear body can be obtained by spinning a dispersion of carbon nanotubes. The manufacture of a carbon nanotube linear body by spinning can be performed, for example, by the method disclosed in U.S. Patent Application Publication No. 2013/0251619 (JP Patent Publication No. 2012-126635). From the viewpoint of obtaining uniformity in the diameter of the carbon nanotube linear body, it is preferable to use a thread-like carbon nanotube linear body, and from the viewpoint of obtaining a carbon nanotube linear body with high purity, it is preferable to obtain a thread-like carbon nanotube linear body by twisting a carbon nanotube sheet. The carbon nanotube linear body may be a linear body in which two or more carbon nanotube linear bodies are woven together. In addition, the carbon nanotube linear body may be a linear body in which carbon nanotubes are composited with other conductive materials (hereinafter also referred to as a "composite linear body").

Examples of the composite linear body include (1) a composite linear body in which, in a process of obtaining a carbon nanotube linear body by drawing carbon nanotubes into a sheet shape from an end of a carbon nanotube forest, bundling the drawn carbon nanotube sheet, and then twisting the bundles of carbon nanotubes, a metal element or a metal alloy is supported on the surface of the forest, sheet, or bundle of carbon nanotubes, or the twisted linear body, by vapor deposition, ion plating, sputtering, wet plating, or the like, (2) a composite linear body in which a bundle of carbon nanotubes is twisted together with a linear body of a metal element or a linear body of a metal alloy, or a composite linear body, (3) a composite linear body in which a linear body of a metal element or a linear body of a metal alloy, or a composite linear body, is braided with a carbon nanotube linear body or a composite linear body, etc. In the composite linear body of (2), when twisting the bundles of carbon nanotubes, a metal may be supported on the carbon nanotubes as in the composite linear body of (1). In addition, the composite linear body of (3) is a composite linear body in which two linear bodies are woven together, but as long as it contains at least one linear body of a simple metal or a linear body of a metal alloy, or a composite linear body, it may be a composite linear body in which three or more carbon nanotube linear bodies, or linear bodies of a simple metal or a linear body of a metal alloy, or a composite linear body are woven together.
Examples of the metal for the composite linear body include metal elements such as gold, silver, copper, iron, aluminum, nickel, chromium, tin, and zinc, as well as alloys containing at least one of these metal elements (such as copper-nickel-phosphorus alloys and copper-iron-phosphorus-zinc alloys).

The conductive linear body 21 may be a linear body in which a conductive coating is applied to the thread. Examples of the thread include threads spun from resins such as nylon and polyester. Examples of the conductive coating include coatings of metals, conductive polymers, carbon materials, etc. The conductive coating can be formed by plating, vapor deposition, etc. A linear body in which a conductive coating is applied to the thread can improve the conductivity of the linear body while maintaining the flexibility of the thread. In other words, it becomes easier to reduce the resistance of the pseudo sheet structure 2.

(Resin Layer)
The resin layer 3 is a layer containing resin. The pseudo sheet structure 2 can be directly or indirectly supported by this resin layer 3. In addition, it is preferable that the resin layer 3 is a layer containing an adhesive. When the pseudo sheet structure 2 is formed on the resin layer 3, the adhesive makes it easy to attach the conductive linear body 21 to the resin layer 3. In addition, it is preferable that the resin layer 3 has elasticity. In such a case, the elasticity of the wiring sheet 100 can be ensured.

The resin layer 3 may be a layer made of a resin that can be dried or cured. This provides the resin layer 3 with sufficient hardness to protect the pseudo sheet structure 2, and the resin layer 3 also functions as a protective film. In addition, the resin layer 3 after curing or drying has impact resistance, and deformation of the resin layer 3 due to impact can also be suppressed.

The resin layer 3 is preferably energy ray curable, such as ultraviolet light, visible energy rays, infrared rays, or electron beams, since it can be easily cured in a short time. Note that "energy ray curing" also includes heat curing by heating using energy rays.

The adhesive of the resin layer 3 may be a thermosetting type that hardens when heated, a so-called heat seal type that bonds when heated, or an adhesive that becomes sticky when moistened. However, for ease of application, it is preferable that the resin layer 3 is energy ray curable. Examples of energy ray curable resins include compounds that have at least one polymerizable double bond in the molecule, and acrylate compounds having a (meth)acryloyl group are preferred.

Examples of the acrylate-based compounds include (meth)acrylates containing a chain aliphatic skeleton (trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. acrylates, etc.), alicyclic skeleton-containing (meth)acrylates (dicyclopentanyl di(meth)acrylate, dicyclopentadiene di(meth)acrylate, etc.), polyalkylene glycol (meth)acrylates (polyethylene glycol di(meth)acrylate, etc.), oligoester (meth)acrylates, urethane (meth)acrylate oligomers, epoxy-modified (meth)acrylates, polyether (meth)acrylates other than the above-mentioned polyalkylene glycol (meth)acrylates, and itaconic acid oligomers.

The weight average molecular weight (Mw) of the energy ray curable resin is preferably 100 to 30,000, and more preferably 300 to 10,000.

The adhesive composition may contain one type of energy ray curable resin, or two or more types. When two or more types are contained, the combination and ratio of the resins may be selected as desired. Furthermore, the adhesive composition may be combined with a thermoplastic resin, which will be described later, and the combination and ratio of the resins may be selected as desired.

The resin layer 3 may be an adhesive layer formed from an adhesive (pressure-sensitive adhesive). The adhesive of the adhesive layer is not particularly limited. For example, adhesives include acrylic adhesives, urethane adhesives, rubber adhesives, polyester adhesives, silicone adhesives, and polyvinyl ether adhesives. Among these, the adhesive is preferably at least one selected from the group consisting of acrylic adhesives, urethane adhesives, and rubber adhesives, and more preferably an acrylic adhesive.

Examples of acrylic adhesives include polymers containing structural units derived from alkyl (meth)acrylates having a straight-chain alkyl group or a branched-chain alkyl group (i.e., polymers obtained by polymerizing at least alkyl (meth)acrylates), and acrylic polymers containing structural units derived from (meth)acrylates having a cyclic structure (i.e., polymers obtained by polymerizing at least (meth)acrylates having a cyclic structure). Here, "(meth)acrylate" is used as a term that refers to both "acrylate" and "methacrylate," and the same applies to other similar terms.

The acrylic copolymer may be crosslinked with a crosslinking agent. Examples of crosslinking agents include known epoxy crosslinking agents, isocyanate crosslinking agents, aziridine crosslinking agents, and metal chelate crosslinking agents. When crosslinking the acrylic copolymer, a hydroxyl group, a carboxyl group, or the like that reacts with these crosslinking agents can be introduced into the acrylic copolymer as a functional group derived from the monomer component of the acrylic polymer.

When the resin layer 3 is formed from an adhesive, the resin layer 3 may further contain the above-mentioned energy ray curable resin in addition to the adhesive. When an acrylic adhesive is used as the adhesive, a compound having both a functional group that reacts with a functional group derived from a monomer component in an acrylic copolymer and a functional group that is polymerizable with energy rays in one molecule may be used as the energy ray curable component. The reaction between the functional group of the compound and the functional group derived from a monomer component in an acrylic copolymer makes the side chain of the acrylic copolymer polymerizable by energy ray irradiation. Even when the adhesive is other than an acrylic adhesive, a component whose side chain is similarly energy ray polymerizable may be used as a polymer component other than an acrylic polymer.

The thermosetting resin used in the resin layer 3 is not particularly limited, and specific examples include epoxy resin, phenol resin, melamine resin, urea resin, polyester resin, urethane resin, acrylic resin, benzoxazine resin, phenoxy resin, amine-based compound, acid anhydride-based compound, etc. These can be used alone or in combination of two or more. Among these, from the viewpoint of suitability for curing using an imidazole-based curing catalyst, it is preferable to use epoxy resin, phenol resin, melamine resin, urea resin, amine-based compound, and acid anhydride-based compound, and in particular, from the viewpoint of showing excellent curing properties, it is preferable to use epoxy resin, phenol resin, a mixture thereof, or a mixture of epoxy resin and at least one selected from the group consisting of phenol resin, melamine resin, urea resin, amine-based compound, and acid anhydride-based compound.

The moisture-curable resin used in the resin layer 3 is not particularly limited, but examples include urethane resin, which is a resin that generates isocyanate groups when exposed to moisture, and modified silicone resin.

When using an energy ray curable resin or a thermosetting resin, it is preferable to use a photopolymerization initiator or a thermal polymerization initiator. By using a photopolymerization initiator or a thermal polymerization initiator, a crosslinked structure is formed, making it possible to more firmly protect the pseudo sheet structure 2.

Photopolymerization initiators include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, 2-chloroanthraquinone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenyl-phosphine oxide.

Thermal polymerization initiators include hydrogen peroxide, peroxodisulfates (ammonium peroxodisulfate, sodium peroxodisulfate, potassium peroxodisulfate, etc.), azo compounds (2,2'-azobis(2-amidinopropane) dihydrochloride, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), etc.), and organic peroxides (benzoyl peroxide, lauroyl peroxide, peracetic acid, persuccinic acid, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, etc.).

These polymerization initiators may be used alone or in combination of two or more.
When these polymerization initiators are used to form a crosslinked structure, the amount used is preferably 0.1 parts by mass or more and 100 parts by mass or less, more preferably 1 part by mass or more and 100 parts by mass or less, and particularly preferably 1 part by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the energy ray-curable resin or the thermosetting resin.

The resin layer 3 may not be curable, and may be, for example, a layer made of a thermoplastic resin composition. The thermoplastic resin layer can be softened by including a solvent in the thermoplastic resin composition. This makes it easier to attach the conductive linear body 21 to the resin layer 3 when forming the pseudo sheet structure 2 on the resin layer 3. On the other hand, the thermoplastic resin layer can be dried and solidified by volatilizing the solvent in the thermoplastic resin composition.

Examples of the thermoplastic resin include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polyether, polyethersulfone, polyimide, and acrylic resin.
Examples of the solvent include alcohol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, hydrocarbon-based solvents, alkyl halide solvents, and water.

The resin layer 3 may contain an inorganic filler. By containing an inorganic filler, the hardness of the resin layer 3 after curing can be further improved. In addition, the thermal conductivity of the resin layer 3 is improved.

Examples of inorganic fillers include inorganic powders (e.g., powders of silica, alumina, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, metals, and boron nitride), beads made by spheroidizing inorganic powders, single crystal fibers, and glass fibers. Among these, silica filler and alumina filler are preferred as inorganic fillers. One type of inorganic filler may be used alone, or two or more types may be used in combination.

The resin layer 3 may contain other components. Examples of other components include well-known additives such as organic solvents, flame retardants, tackifiers, UV absorbers, antioxidants, preservatives, antifungal agents, plasticizers, defoamers, and wettability adjusters.

The thickness of the resin layer 3 is appropriately determined depending on the application of the wiring sheet 100. For example, from the viewpoint of adhesion, the thickness of the resin layer 3 is preferably 3 μm or more and 150 μm or less, and more preferably 5 μm or more and 100 μm or less.

(electrode)
The electrodes 4 are used to supply a current to the conductive linear body 21. The electrodes 4 are in direct contact with the conductive linear body 21. The electrodes 4 are disposed so as to be electrically connected to both ends of the conductive linear body 21.
Each electrode 4 includes a metal wire 41 provided with a power supply unit 5. In a plan view of the wiring sheet, each electrode 4 includes another metal wire 41 located inside the metal wire 41 provided with the power supply unit 5. The number of the another metal wires 41 may be one or more, is preferably two or more, and is more preferably three or more.
Furthermore, the number of metal wires 41 used in one electrode 4 of the pair of electrodes 4 may be different from the number of metal wires 41 used in the other electrode 4. However, from the viewpoint of suppressing temperature unevenness, it is preferable that the number of metal wires 41 used in one electrode 4 is the same as the number of metal wires 41 used in the other electrode 4. From the same viewpoint, it is preferable that the metal wires 41 constituting the pair of electrodes 4 are line-symmetrical when viewed in a plan view of the wiring sheet 100.
Moreover, it is preferable that the metal wires 41 have a wave shape in a plan view of the wiring sheet 100. Examples of the wave shape include a sine wave, a rectangular wave, a triangular wave, a sawtooth wave, etc. If the electrode 4 has such a structure, breakage of the electrode 4 can be suppressed when the wiring sheet 100 is stretched in the axial direction of the electrode 4.

Metals for the metal wire 41 include copper, aluminum, tungsten, iron, molybdenum, nickel, titanium, silver, gold, and other metals, or alloys containing two or more metals (e.g., stainless steel, carbon steel, and other steels, brass, phosphor bronze, zirconium-copper alloys, beryllium copper, iron-nickel, nichrome, nickel-titanium, Kanthal, Hastelloy, and rhenium-tungsten, and other metals). The metal wire 41 may also be plated with gold, tin, zinc, silver, nickel, chromium, nickel-chromium alloys, solder, and the like. However, it is preferable that the metal wire 41 is gold plated. In such a case, the contact resistance between the metal wire 41 and the conductive linear body 21 is reduced, so that heat generation in the electrode 4 can be suppressed.

The cross-sectional shape of the metal wire 41 is not particularly limited and may be polygonal, flat, elliptical, circular, or the like, but is preferably elliptical or circular.
When the cross section of the metal wire 41 is circular, the thickness (diameter) of the metal wire 41 is preferably 5 μm or more and 1000 μm or less, more preferably 20 μm or more and 500 μm or less, and even more preferably 50 μm or more and 300 μm or less.
When the cross section of the metal wire 41 is elliptical, it is preferable that the major axis is in the same range as the diameter described above.

Adjacent metal wires 41 may be in contact with each other, but it is preferable that they are not in contact with each other.
The interval between adjacent metal wires 41 is preferably 0.5 mm to 15 mm, more preferably 1 mm to 10 mm, and even more preferably 1 mm to 5 mm. If the interval between adjacent metal wires 41 is equal to or greater than the lower limit, electrical conduction between adjacent metal wires 41 can be reliably prevented. If the interval between adjacent metal wires 41 is equal to or less than the upper limit, temperature unevenness can be more effectively suppressed.

Of the metal wires 41 that make up the electrode 4, the distance between the outermost metal wire 41 and the innermost metal wire 41 is preferably 3 mm or more and 30 mm or less, and more preferably 5 mm or more and 20 mm or less. If this distance is within the above range, it is easy to adjust the number of metal wires 41, etc.

(Power supply section)
The power supply portion 5 is a portion that applies a voltage to the wiring sheet 100. When the electrode 4 is exposed and can be electrically connected, any portion of the electrode 4 can be used as the power supply portion 5.
A power supply unit 5 may be provided separately to facilitate connection of a power source (not shown) to the electrode 4. In this case, the material of the power supply unit 5 may be the same as that of the electrode 4. In addition, in the case where the electrode 4 is covered with an insulating material to prevent short circuits, etc., a portion of the insulating material that has been partially removed may serve as the power supply unit 5.

(Method of manufacturing wiring sheet)
There are no particular limitations on the method for producing the wiring sheet 100 according to the present embodiment. The wiring sheet 100 can be produced, for example, by the following steps.
First, a composition for forming the resin layer 3 is applied onto the substrate 1 to form a coating film. Next, the coating film is dried to prepare the resin layer 3. Next, the conductive linear bodies 21 are arranged on the resin layer 3 to form the pseudo sheet structure 2. For example, in a state where the resin layer 3 with the substrate 1 is arranged on the outer circumferential surface of the drum member, the conductive linear bodies 21 are spirally wound around the resin layer 3 while rotating the drum member. Then, the bundle of the spirally wound conductive linear bodies 21 is cut along the axial direction of the drum member. This forms the pseudo sheet structure 2 and places it on the resin layer 3. Then, the resin layer 3 with the substrate 1 on which the pseudo sheet structure 2 is formed is taken out from the drum member to obtain a sheet-like conductive member. According to this method, for example, by moving the unwinding portion of the conductive linear bodies 21 along a direction parallel to the axis of the drum member while rotating the drum member, it is easy to adjust the interval L between adjacent conductive linear bodies 21 in the pseudo sheet structure 2.
Next, a pair of electrodes 4 (two metal wires 41) are attached to both ends of the conductive linear body 21 in the pseudo sheet structure 2 of the sheet-like conductive member. Subsequently, of the metal wires 41 constituting the pair of electrodes 4, the metal wires 41 that are outermost in a plan view of the wiring sheet 100 are each provided with a power supply portion 5, thereby producing the wiring sheet 100.

(Functions and Effects of the First Embodiment)
According to this embodiment, the following advantageous effects can be obtained.
(1) In this embodiment, another metal wire 41 is provided inside the metal wire 41 on which the power supply unit 5 is provided. Therefore, when a current is passed through the wiring sheet 100 to generate heat, a current also flows through this other metal wire 41. As a result, the resistance value of the electrode 4 can be reduced, and temperature unevenness in the wiring sheet 100 can be suppressed.

[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the contents of this embodiment. In the drawings, some parts are illustrated enlarged or reduced in size for ease of explanation.
In the second embodiment, the method of providing the metal wire 41 on the inner side of the metal wire 41 on which the power supply unit 5 is provided is different from that in the first embodiment.
In the following description, differences from the first embodiment will be mainly described, and overlapping descriptions will be omitted or simplified. The same reference numerals will be used to designate the same components as those in the first embodiment, and descriptions thereof will be omitted or simplified.

3, the wiring sheet 100A according to the present embodiment includes a substrate 1, a pseudo sheet structure 2, a resin layer 3, and a pair of electrodes 4. Each of the pair of electrodes 4 includes a metal wire 41 provided with a power supply portion 5.
In a plan view of wiring sheet 100A, metal wire 41 starts from power supply portion 5 at one end of pseudo sheet structure 2 and is folded back when it reaches the opposite end of pseudo sheet structure 2. After being folded back, metal wire 41 starts from the opposite end of pseudo sheet structure 2 and reaches one end of pseudo sheet structure 2.
In this embodiment, the electrode 4 consists of a single metal wire 41, but as described above, when viewed in a plan view of the wiring sheet 100A, the metal wire 41 is located inside the metal wire 41 on which the power supply portion 5 is provided.

(Functions and Effects of the Second Embodiment)
According to this embodiment, in addition to the effect (1) in the first embodiment, the following effect (2) can be achieved.
(2) According to this embodiment, even though the electrode 4 is composed of a single metal wire 41, when viewed in a plan view of the wiring sheet 100A, the metal wire 41 can be provided inside the metal wire 41 on which the power supply portion 5 is provided.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the contents of this embodiment. In the drawings, some parts are illustrated enlarged or reduced in size for ease of explanation.
In the third embodiment, the method of providing the metal wire 41 on the inner side of the metal wire 41 on which the power supply unit 5 is provided is different from that in the first embodiment.
In the following description, differences from the first embodiment will be mainly described, and overlapping descriptions will be omitted or simplified. The same reference numerals will be used to designate the same components as those in the first embodiment, and descriptions thereof will be omitted or simplified.

4, the wiring sheet 100B according to the present embodiment includes a substrate 1, a pseudo sheet structure 2, a resin layer 3, and a pair of electrodes 4. Each of the pair of electrodes 4 includes a metal wire 41 provided with a power supply portion 5.
In a plan view of wiring sheet 100B, metal wire 41 starts from power supply portion 5 at one end of pseudo sheet structure 2 and is folded back when it reaches the opposite end of pseudo sheet structure 2. After being folded back, metal wire 41 starts from the opposite end of pseudo sheet structure 2 and is folded back when it reaches one end of pseudo sheet structure 2, and thereafter is folded back at the end in the same manner.
In this embodiment, the number of times of folding is three, but is not limited thereto. The number of times of folding is not particularly limited to an upper limit, but is usually 10 or less, preferably 3 to 7, and more preferably 3 to 5. The more the number of times of folding, the more metal wires 41 can be provided inside the metal wire 41 provided with the power supply unit 5.
In this embodiment, the electrode 4 consists of a single metal wire 41, but as described above, when viewed in a plan view of the wiring sheet 100B, the electrode 4 is configured to have multiple metal wires 41 located inside the metal wire 41 on which the power supply portion 5 is provided.

(Effects of the Third Embodiment)
According to this embodiment, it is possible to achieve the effect (1) of the first embodiment and the effect (2) of the second embodiment.

[Modifications of the embodiment]
The present invention is not limited to the above-described embodiment, and includes modifications and improvements within the scope of the present invention that can achieve the object of the present invention.
For example, in the above-described embodiment, the wiring sheet 100 includes the base material 1, but is not limited thereto. For example, the wiring sheet 100 does not need to include the base material 1. In such a case, the wiring sheet 100 can be used by being attached to an adherend by the resin layer 3.
In the above-described embodiment, wiring sheet 100 includes resin layer 3, but is not limited to this. For example, wiring sheet 100 does not need to include resin layer 3. In such a case, a knitted fabric may be used as substrate 1, and conductive linear members 21 may be woven into substrate 1 to form pseudo sheet structure 2.

The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples.

[Example 1]
An acrylic adhesive ("PK" manufactured by Lintec Corporation) was applied to a thickness of 20 μm on a PET film having a thickness of 50 μm to prepare an adhesive sheet. A gold-plated tungsten wire (diameter 25 μm, "Au(0.1)-TWG" manufactured by Tokusai Corporation) was prepared as the conductive linear body. Next, the above-mentioned adhesive sheet was wound around a drum member having an outer circumferential surface made of rubber, with the surface of the pressure-sensitive adhesive layer facing outward so as not to wrinkle, and both ends of the above-mentioned adhesive sheet in the circumferential direction were fixed with double-sided tape. The conductive linear body wound around the bobbin was attached to the surface of the pressure-sensitive adhesive layer of the adhesive sheet located near the end of the drum member, and the wire was wound around the drum member while being unwound, and the drum member was gradually moved in a direction parallel to the drum axis so that the conductive linear body was wound around the drum member while drawing a spiral at equal intervals. Thirty conductive linear bodies were provided at equal intervals, with an interval of 10 mm.
Next, two metal wires (gold-plated copper wire, diameter 150 μm, "C1100-H AuP" manufactured by Tokusai Corporation) were prepared as electrodes. Next, the two metal wires were placed on both ends of the conductive linear body with a gap of 10 mm in a direction perpendicular to the direction in which the conductive linear body extends, so that the distance between the electrodes was 200 mm, and electrodes were attached. Then, a PET film with a thickness of 50 μm was attached to the adhesive surface on which the conductive linear body of the electrode-attached film was placed, to prepare a sheet heater. Note that the two power supply parts for energization were provided on the metal wires located on the outermost side in a plan view of the sheet heater.

[Example 2]
A sheet-shaped heater was produced in the same manner as in Example 1, except that four metal wires were prepared as electrodes and attached with an interval of 2.5 mm between each wire.

[Example 3]
A sheet-type heater was produced in the same manner as in Example 1, except that the electrodes were configured as shown in FIG.
That is, in Example 3, the electrodes were provided as follows. In a plan view of the sheet-like heater, the metal wire started from one end of the pseudo sheet structure and was folded back when it reached the opposite end of the pseudo sheet structure. Furthermore, after being folded back, the metal wire started from the opposite end of the pseudo sheet structure and reached one end of the pseudo sheet structure. Here, the spacing between the metal wires was 10 mm. Furthermore, the two power supply points for current flow were provided at the starting points of the metal wires.

[Example 4]
A sheet-type heater was produced in the same manner as in Example 1, except that the electrodes were configured as shown in FIG.
That is, in Example 4, the electrodes were provided as follows. In a plan view of the sheet-like heater, the metal wire started from one end of the pseudo sheet structure and was folded back when it reached the opposite end of the pseudo sheet structure. Furthermore, after being folded back, the metal wire started from the opposite end of the pseudo sheet structure and was folded back when it reached one end of the pseudo sheet structure, and thereafter was folded back in the same manner at the ends. Here, the number of folds was three, and the spacing between the metal wires was 2.5 mm. Furthermore, the two power supply parts for applying electricity were provided at the starting points of the metal wire, respectively.

[Comparative Example 1]
A sheet-type heater was produced in the same manner as in Example 1, except that the two power supply parts for energizing were provided on the metal wires located on the innermost side in a plan view of the sheet-type heater.
FIG. 5 is a schematic diagram showing the sheet heater obtained in Comparative Example 1.

[Comparative Example 2]
A sheet-type heater was produced in the same manner as in Example 2, except that the two power supply parts for energizing were provided on the metal wires located on the innermost side in a plan view of the sheet-type heater.

[Temperature difference evaluation]
A current of 3.5 A was passed through the sheet heater to generate heat, and the temperature distribution of the sheet heater was then measured using a thermographic camera (FLIR C2 manufactured by FLIR) from a position 150 mm from the surface of the sheet heater. The emissivity was set to 0.95. The difference in temperature between the conductive linear body located at the end of the power supply side of the sheet heater and the conductive linear body located at the end opposite the power supply side was taken as the temperature difference (unit: °C). The smaller this temperature difference, the more the temperature unevenness is suppressed. The results are shown in Table 1.

From the results shown in Table 1, it was confirmed that when the metal wire is provided inside the metal wire on which the power supply portion is provided (Examples 1 to 4) when viewed in plan of the sheet-type heater, temperature unevenness can be suppressed.
In contrast, it was found that when the metal wire was provided outside the metal wire provided with the power supply portion in a plan view of the sheet-type heater (Comparative Examples 1 and 2), temperature unevenness could not be suppressed.

1...substrate, 2...pseudo sheet structure, 21...conductive linear body, 3...resin layer, 4...electrode, 41...metal wire, 5...power supply part, 100, 100A, 100B...wiring sheet.

Claims (5)

A wiring sheet comprising a pseudo sheet structure in which a plurality of conductive linear bodies are arranged at intervals, and a pair of electrodes in direct contact with the conductive linear bodies,
The electrodes each include a metal wire having a power supply portion;
the electrode includes a metal wire having no power supply portion, the metal wire being located on the inner side of the metal wire having the power supply portion in a plan view of the wiring sheet ;
the electrodes are disposed so as to be electrically connected to both ends of the conductive linear body,
Among the metal wires constituting the electrode, the distance between the outermost metal wire and the innermost metal wire is 3 mm or more and 30 mm or less.
Wiring sheet. A wiring sheet comprising a pseudo sheet structure in which a plurality of conductive linear bodies are arranged at intervals, and a pair of electrodes in direct contact with the conductive linear bodies,
The electrodes each include a metal wire having a power supply portion;
the metal wire constituting the electrode has a structure in which, in a plan view of the wiring sheet, it starts from one end of the pseudo sheet structure and folds back when it reaches the opposite end of the pseudo sheet structure;
the electrode includes a metal wire that is folded back at the end portion on the inner side of the metal wire on which the power supply portion is provided in a plan view of the wiring sheet ,
the electrodes are disposed so as to be electrically connected to both ends of the conductive linear body,
Among the metal wires constituting the electrode, the distance between the outermost metal wire and the innermost metal wire is 3 mm or more and 30 mm or less.
Wiring sheet. The wiring sheet according to claim 1 or 2 ,
The metal wire is gold plated.
Wiring sheet. The wiring sheet according to claim 1 ,
Among the metal wires constituting the electrode, the distance between adjacent metal wires is 0.5 mm or more and 15 mm or less.
Wiring sheet. The wiring sheet according to claim 1 ,
The metal wires constituting the pair of electrodes are line-symmetrical in a plan view of the wiring sheet.
Wiring sheet.

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