Wiring sheet and sheet heater

Abstract

This wiring sheet is provided with a pseudo-sheet structure (2) in which a plurality of electrically conductive linear bodies (21) are arranged at intervals, a pair of electrodes (4), and a first power supply portion (51) and a second power supply portion (52) provided on each electrode (4), wherein, if N is the number of electrically conductive linear bodies (21), rn is the resistance value of the n-th electrically conductive linear body (21), counting from the first power supply portion (51) and second power supply portion (52) side, and R is the resistance value of the electrodes (4), all the conditions represented by formula (F1), formula (F2), and formula (F3) are satisfied. (F1): r1 / R≤300 (F2): rn+1≤rn (In formula (F2), n is an integer at least equal to 1.) (F3): 0<r1-rN

Description

Technical Field

[0001] The present invention relates to a wiring sheet and a sheet heater.

Background Art

[0002] A sheet-like conductive member having a pseudo-sheet structure in which a plurality of conductive linear bodies are arranged at intervals (hereinafter, also referred to as a "conductive sheet") may be used as a member of various articles such as a heating element of a heating device, a material of a heating textile, and a protection film for a display (antistatic film). As a sheet used for a heating element, for example, Patent Document 1 describes a conductive sheet having a pseudo-sheet structure in which a plurality of linear bodies extending in one direction are arranged at intervals. And, by providing a pair of electrodes at both ends of the plurality of linear bodies, a wiring sheet that can be used as a heating element can be obtained.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As an electrode used for a wiring sheet, usually, a metal foil or a silver paste is used. However, from the viewpoint of the flexibility of the electrode portion of the wiring sheet, it has been studied to use a metal wire or the like instead of the metal foil or the silver paste. On the other hand, when a thin electrode such as a metal wire is used as the electrode, the resistance value of the electrode becomes relatively large. Therefore, the resistance value of the electrode that should originally be negligible becomes non-negligible. As a result, it has been found that temperature unevenness may occur when current is passed through the wiring sheet to generate heat.

[0005] An object of the present invention is to provide a wiring sheet and a sheet heater capable of suppressing temperature unevenness.

Means for Solving the Problems

[0006] A wiring sheet according to an aspect of the present invention includes a pseudo-sheet structure in which a plurality of conductive linear bodies are arranged at intervals, a pair of electrodes, and a first power supply unit and a second power supply unit provided on the electrodes respectively. Let the number of the conductive linear bodies be N, and the resistance value of the n-th conductive linear body counted from the sides of the first power supply unit and the second power supply unit be r n When the resistance value of the electrode is R, it is characterized by satisfying all the conditions shown by the following mathematical formula (F1), the following mathematical formula (F2), and the following mathematical formula (F3). r1 / R ≤ 300 ···(F1) r n+1 ≤ r n ···(F2) (In the mathematical formula (F2), n is an integer of 1 or more.) 0 < r1 - r N ···(F3)

[0007] In a wiring sheet according to an aspect of the present invention, it is preferable to satisfy the condition shown by the following mathematical formula (F3-1). r1 - r N ≤ NR ···(F3-1)

[0008] In a wiring sheet according to an aspect of the present invention, the interval between the conductive linear bodies is preferably 20 mm or less.

[0009] In a wiring sheet according to an aspect of the present invention, in a plan view of the pseudo-sheet structure, the width of the electrode is preferably 100 mm or less.

[0010] In a wiring sheet according to an aspect of the present invention, it is preferable to further include a base material that supports the pseudo-sheet structure.

[0011] The sheet heater according to one aspect of the present invention is characterized by including the wiring sheet according to one aspect of the present invention described above.

[0012] According to the present invention, it is possible to provide a wiring sheet and a sheet heater capable of suppressing temperature unevenness.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0014] [First Embodiment] Hereinafter, the present invention will be described with reference to the drawings by taking embodiments as examples. The present invention is not limited to the contents of the embodiments. In the drawings, there are parts shown enlarged or reduced for ease of explanation.

[0015] (Wiring Sheet) As shown in FIGS. 1 and 2, the wiring sheet 100 according to this embodiment includes a base material 1, a pseudo-sheet structure 2, a resin layer 3, and a pair of electrodes 4. Specifically, in the wiring sheet 100, the resin layer 3 is laminated on the base material 1, and the pseudo-sheet structure 2 is laminated on the resin layer 3. The pseudo-sheet structure 2 has a plurality of conductive linear bodies 21 arranged at intervals. One electrode 4 is provided with a first power supply unit 51, and the other electrode 4 is provided with a second power supply unit 52.

[0016] In this embodiment, the number of the conductive linear bodies 21 is N, and the resistance value of the n-th conductive linear body 21 counted from the sides of the first power supply unit 51 and the second power supply unit 52 is r n [Ω], and when the resistance value of the electrode 4 is R [Ω], it is necessary to satisfy all the conditions shown by the following mathematical formulas (F1), (F2), and (F3). Here, the "n-th conductive linear body counted from the sides of the first power supply unit 51 and the second power supply unit 52" refers to the conductive linear body 21 electrically connected to the pair of electrodes 4, and when counting along the wiring of the wiring sheet 100 from the first power supply unit 51 and the second power supply unit 52, it refers to the n-th conductive linear body 21.

[0017] In this embodiment, it is necessary to satisfy the condition shown by the following mathematical formula (F1). r1 / R ≦ 300 ···(F1)

[0018] When the value of r1 / R exceeds 300, the resistance value of the conductive linear body 21, which is the heat generating part, is sufficiently larger than the resistance value of the electrode 4. Therefore, in the wiring sheet 100, the resistance value of the electrode 4 can be almost ignored, and basically, the problem of temperature unevenness is less likely to occur. On the contrary, as the value of r1 / R becomes smaller, the problem of temperature unevenness is more likely to occur. Therefore, the significance of using the wiring sheet 100 according to this embodiment increases. The value of r1 / R may be 200 or less, or may be 100 or less. However, if the value of r1 / R is too small, the electrode 4 will also generate heat. Therefore, the value of r1 / R is preferably 10 or more.

[0019] In this embodiment, it is necessary to satisfy the condition represented by the following mathematical formula (F2). r n+1 ≤ r n ···(F2)

[0020] When the condition represented by the mathematical formula (F2) is not satisfied, temperature unevenness cannot be suppressed. In the mathematical formula (F2), n is an integer of 1 or more. And the upper limit of n is the number N of the conductive linear bodies 21. The number N of the conductive linear bodies 21 is preferably 3 or more, more preferably 5 or more, and even more preferably 10 or more. Although temperature unevenness tends to occur more easily as the number of the conductive linear bodies 21 increases, even when the number of the conductive linear bodies 21 is large, according to the wiring sheet 100 according to this embodiment, temperature unevenness can be suppressed. Further, the upper limit of the number N of the conductive linear bodies 21 is not particularly limited, but is, for example, 150.

[0021] In this embodiment, it is necessary to satisfy the condition represented by the following mathematical formula (F3). 0 < r1 - r N ···(F3)

[0022] When the condition represented by the mathematical formula (F3) is not satisfied, temperature unevenness cannot be suppressed. Further, from the viewpoint of further suppressing temperature unevenness, it is preferable to satisfy the condition represented by the following mathematical formula (F3-1). r1 - r N ≤ NR ···(F3-1) That is, if the value of r1 - r N is equal to or less than the numerical value obtained by multiplying the number N of the conductive linear bodies 21 by the resistance value R of the electrode 4, temperature unevenness can be further suppressed. Further, from the same viewpoint, the value of r1 - r N is more preferably equal to or more than NR / 8 and equal to or less than NR, even more preferably equal to or more than NR / 4 and equal to or less than NR, and particularly preferably equal to or more than NR / 2 and equal to or less than NR.

[0023] When all the conditions shown in mathematical expressions (F1), (F2), and (F3) are satisfied, the inventors presume that the reason why temperature unevenness can be suppressed is as follows. That is, when the condition of the mathematical expression (F1) is satisfied, the ratio of the resistance value of the conductive linear body 21, which is the heat-generating part, to the resistance value of the electrode 4 becomes small, and the resistance value of the electrode 4, which should originally be negligible, cannot be ignored. 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 influence of the resistance of the electrode 4 up to the conductive linear body 21 becomes large in the conductive linear body 21 distal to the first power supply part 51 and the second power supply part 52. Therefore, when a current is passed through the wiring sheet 100 to generate heat, the inventors presume that the current flowing through this conductive linear body 21 becomes relatively small and the temperature becomes lower compared to other conductive linear bodies 21. On the other hand, when the conditions shown in the mathematical expressions (F2) and (F3) are satisfied, the resistance value r of the nth conductive linear body 21 decreases as it is farther from the first power supply part 51 and the second power supply part 52. n And although the influence of the resistance of the electrode 4 up to the conductive linear body 21 becomes large in the conductive linear body 21 distal to the first power supply part 51 and the second power supply part 52, it can be offset by the decrease in the resistance value r of the conductive linear body 21. In this way, the inventors presume that temperature unevenness can be suppressed. n

[0024] The resistance value of the conductive linear body 21 and the resistance value of the electrode 4 can be set by appropriately known methods. For example, they can be adjusted by changing the material, cross-sectional area, length, etc. For example, as shown in FIG. 1, if the length of the conductive linear body 21 is made shorter as it is farther from the first power supply part 51 and the second power supply part 52, the resistance value of the conductive linear body 21 can be made lower as it is farther from the first power supply part 51 and the second power supply part 52. Also, the resistance value can be made smaller by increasing the electrical conductivity or the cross-sectional area of the conductive linear body 21.

[0025] (Base material) Examples of the base material 1 include synthetic resin films, paper, metal foils, nonwoven fabrics, cloth, and glass films. The base material 1 can directly or indirectly support the pseudo-sheet structure 2. Further, the base material 1 is preferably a flexible base material. As the flexible base material, synthetic resin films, paper, nonwoven fabrics, cloth, etc. can be used. Among these flexible base materials, synthetic resin films, nonwoven fabrics, or cloth are preferable, and nonwoven fabrics or cloth are more preferable. Examples of the synthetic resin film include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate copolymer film, ionomer resin film, ethylene·(meth)acrylic acid copolymer film, ethylene·(meth)acrylate copolymer film, polystyrene film, polycarbonate film, and polyimide film, etc. In addition, examples of the flexible base material include these crosslinked films and laminated films, etc. Examples of the paper include high-quality paper, recycled paper, and kraft paper, etc. Examples of the nonwoven fabric include spunbond nonwoven fabric, needle-punched nonwoven fabric, meltblown nonwoven fabric, and spunlace nonwoven fabric, etc. Examples of the cloth include woven fabrics and knitted fabrics, etc. The paper, nonwoven fabric, and cloth as the flexible base material are not limited to these.

[0026] (Pseudo-sheet structure) The pseudo-sheet structure 2 has a structure in which a plurality of conductive linear bodies 21 are arranged at intervals from each other. That is, the pseudo-sheet structure 2 is a structure in which a plurality of conductive linear bodies 21 are arranged at intervals from each other so as to form a plane or a curved surface. The conductive linear body 21 is linear in a plan view of the wiring sheet 100. And the pseudo-sheet structure 2 has a structure in which a plurality of conductive linear bodies 21 are arranged in a direction intersecting the axial direction of the conductive linear body 21. Note that the conductive linear body 21 may have a wavy shape in a plan view of the wiring sheet 100. Specifically as the wavy shape, the conductive linear body 21 may have a wavy shape such as a sine wave, a circular wave, a rectangular wave, a triangular wave, and a sawtooth wave, for example. If the pseudo-sheet structure 2 has such a structure, disconnection 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.

[0027] The volume resistivity of the conductive linear body 21 is 1.0×10 -9 Ω·m or more and 1.0×10 -3 Ω·m or less, 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 within the above range, the surface resistance of the pseudo-sheet structure 2 is likely to decrease. The measurement of the volume resistivity of the conductive linear body 21 is as follows. Silver paste is applied to one end of the conductive linear body 21 and a portion 40 mm in length from the end, the resistance of the end and the portion 40 mm in length from the end is measured, and the resistance value of the conductive linear body 21 is obtained. Then, the cross-sectional area (unit: m 2 ) of the conductive linear body 21 is multiplied by the above resistance value, and the obtained value is divided by the above-measured length (0.04 m) to calculate the volume resistivity of the conductive linear body 21.

[0028] The shape of the cross-section of the conductive linear body 21 is not particularly limited, and can be a polygon, a flat shape, an elliptical shape, a circular shape, etc., but from the viewpoint of compatibility with the resin layer 3 and the like, an elliptical shape or a circular shape is preferable. When the cross-section of the conductive linear body 21 is circular, the thickness (diameter) D (see FIG. 2) of the conductive linear body 21 is preferably 5 μm or more and 3 mm 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 body 21 is more preferably 8 μm or more and 1 mm or less, and even more preferably 12 μm or more and 100 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 above diameter D.

[0029] The diameter D of the conductive linear body 21 is measured by observing the conductive linear body 21 of the pseudo-sheet structure 2 using a digital microscope, and measuring the diameter of the conductive linear body 21 at five randomly selected locations, and taking the average value thereof.

[0030] The interval L (see Fig. 2) between the conductive linear bodies 21 is preferably 20 mm or less, more preferably 0.5 mm or more and 15 mm or less, and even more preferably 1 mm or more and 10 mm or less. If the interval between the conductive linear bodies 21 is within the above range, since the conductive linear bodies are somewhat dense, the resistance of the pseudo-sheet structure can be kept low, and the distribution of the temperature rise when the wiring sheet 100 is used as a heating element can be made uniform, etc., and the function of the wiring sheet 100 can be improved.

[0031] The interval L between the conductive linear bodies 21 is measured by observing the conductive linear bodies 21 of the pseudo-sheet structure 2 using visual observation or a digital microscope, and measuring the interval between two adjacent conductive linear bodies 21. Note that 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 the opposing portions of the two conductive linear bodies 21 (see Fig. 2). When the arrangement of the conductive linear bodies 21 is uneven, the interval L is the average value of the intervals between all adjacent conductive linear bodies 21.

[0032] The conductive linear body 21 is not particularly limited, but is preferably a linear body containing a metal wire (hereinafter also referred to as a "metal wire linear body"). Since the metal wire has high thermal conductivity, high electrical conductivity, high handleability, and versatility, when a metal wire linear body is applied as the conductive linear body 21, the resistance value of the pseudo-sheet structure 2 can be reduced, and the light transmittance is likely to be improved. Further, when the wiring sheet 100 (pseudo-sheet structure 2) is applied as a heating element, rapid heat generation is likely to be realized. Furthermore, as described above, it is easy to obtain a linear body with a small diameter. In addition, examples of the conductive linear body 21 include a linear body containing carbon nanotubes and a linear body with a conductive coating applied to a thread, in addition to a metal wire linear body.

[0033] The metal wire linear body may be a linear body composed of a single metal wire or a linear body formed by twisting a plurality of metal wires. Examples of the metal wire include metals such as copper, aluminum, tungsten, iron, molybdenum, nickel, titanium, silver, and gold, or wires containing an alloy composed of two or more metals (for example, steels such as stainless steel and carbon steel, brass, phosphor bronze, zirconium copper alloy, beryllium copper, iron nickel, nichrome, nickel titanium, kanthal, hastelloy, and rhenium tungsten). Further, the metal wire may be plated with tin, zinc, silver, nickel, chromium, nickel chromium alloy, or solder, etc., or may be coated on the surface with a carbon material or a polymer described later. In particular, a wire containing at least one metal selected from tungsten, molybdenum, and alloys containing these is preferable from the viewpoint of obtaining the conductive linear body 21 with a low volume resistivity. Examples of the metal wire also include a metal wire coated with a carbon material. When the metal wire is coated with a carbon material, the metallic luster is reduced, and it becomes easy to make the presence of the metal wire inconspicuous. Further, when the metal wire is coated with a carbon material, metal corrosion is also suppressed. Examples of the carbon material for coating the metal wire include amorphous carbon (for example, carbon black, activated carbon, hard carbon, soft carbon, mesoporous carbon, and carbon fiber, etc.), graphite, fullerene, graphene, and carbon nanotubes.

[0034] The linear body containing carbon nanotubes can be obtained, for example, by pulling out carbon nanotubes in a sheet form from the end of a carbon nanotube forest (a grown body in which a plurality of carbon nanotubes are grown on a substrate so as to be oriented in a direction perpendicular to the substrate, and may be referred to as an "array"), bundling the pulled-out carbon nanotube sheet, and then 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 can be obtained, and if twist is applied, a thread-shaped linear body can be obtained. The ribbon-shaped carbon nanotube linear body is a linear body having no structure in which carbon nanotubes are twisted. In addition, carbon nanotube linear bodies can also be obtained by spinning from a dispersion of carbon nanotubes or the like. The production of carbon nanotube linear bodies by spinning can be carried out, for example, by the method disclosed in U.S. Patent Application Publication No. 2013 / 0251619 (Japanese Patent Laid-Open No. 2012-126635). From the viewpoint of obtaining uniformity in the diameter of the carbon nanotube linear body, it is desirable to use a thread-shaped carbon nanotube linear body, and from the viewpoint of obtaining a highly pure carbon nanotube linear body, it is preferable to obtain a thread-shaped 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 braided together. Further, the carbon nanotube linear body may be a linear body in which carbon nanotubes and other conductive materials are composite (hereinafter also referred to as a "composite linear body").

[0035] Examples of the composite linear body include: (1) in the process of obtaining a carbon nanotube linear body by pulling out carbon nanotubes in a sheet form from the end of a carbon nanotube forest, bundling the pulled-out carbon nanotube sheet, and then twisting the bundle of carbon nanotubes, a composite linear body in which a simple metal or metal alloy is supported on the surface of the carbon nanotube forest, sheet, bundle, or 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 simple metal linear body, a metal alloy linear body, or a composite linear body; (3) a composite linear body in which a simple metal linear body, a metal alloy linear body, or a composite linear body and a carbon nanotube linear body or a composite linear body are braided. In the composite linear body of (2), when twisting the bundle of carbon nanotubes, a metal may be supported on the carbon nanotubes in the same manner as in the composite linear body of (1). The composite linear body of (3) is a composite linear body formed by braiding two linear bodies, but if it contains at least one simple metal linear body, a metal alloy linear body, or a composite linear body, it may be formed by braiding three or more carbon nanotube linear bodies, simple metal linear bodies, metal alloy linear bodies, or composite linear bodies. Examples of the metal of the composite linear body include simple metals such as gold, silver, copper, iron, aluminum, nickel, chromium, tin, zinc, etc., and alloys containing at least one of these simple metals (such as copper-nickel-phosphorus alloy and copper-iron-phosphorus-zinc alloy).

[0036] The conductive linear body 21 may be a linear body in which a conductive coating is applied to a 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 method, or the like. The linear body with a conductive coating applied to the thread can improve the conductivity of the linear body while maintaining the flexibility of the thread. That is, it becomes easy to reduce the resistance of the pseudo-sheet structure 2. 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 method, or the like. The linear body with a conductive coating applied to the thread can improve the conductivity of the linear body while maintaining the flexibility of the thread. That is, it becomes easy to reduce the resistance of the pseudo-sheet structure 2.

[0037] (Resin layer) The resin layer 3 is a layer containing resin. By this resin layer 3, the pseudo-sheet structure 2 can be supported directly or indirectly. Also, the resin layer 3 is preferably a layer containing an adhesive. When forming the pseudo-sheet structure 2 on the resin layer 3, the adhesive facilitates the attachment of the conductive linear body 21 to the resin layer 3.

[0038] The resin layer 3 may be a layer made of a resin that can be dried or cured. Thereby, sufficient hardness for protecting the pseudo-sheet structure 2 is imparted to the resin layer 3, and the resin layer 3 also functions as a protective film. Further, the resin layer 3 after curing or drying has impact resistance and can suppress deformation of the wiring sheet due to impact.

[0039] The resin layer 3 is preferably energy-ray curable, such as ultraviolet rays, visible energy rays, infrared rays, electron beams, etc., in that it can be cured simply in a short time. Note that "energy-ray curing" includes heat curing by heating using energy rays.

[0040] Examples of the adhesive of the resin layer 3 include a thermosetting one that cures by heat, a so-called heat-seal type that adheres by heat, an adhesive that develops adhesiveness when moistened, etc. However, from the viewpoint of application simplicity, it is preferable that the resin layer 3 is energy-ray curable. Examples of the energy-ray curable resin include compounds having at least one polymerizable double bond in the molecule, and acrylate compounds having a (meth)acryloyl group are preferable.

[0041] Examples of the acrylate compound include chain aliphatic skeleton-containing (meth)acrylates (such as trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxy penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate), cyclic aliphatic skeleton-containing (meth)acrylates (such as dicyclopentanyl di(meth)acrylate and dicyclopentadiene di(meth)acrylate), polyalkylene glycol (meth)acrylates (such as polyethylene glycol di(meth)acrylate), oligoester (meth)acrylates, urethane (meth)acrylate oligomers, epoxy-modified (meth)acrylates, polyethers (meth)acrylates other than the above polyalkylene glycol (meth)acrylates, and itaconic acid oligomers).

[0042] The weight average molecular weight (Mw) of the energy ray-curable resin is preferably from 100 to 30000, more preferably from 300 to 10000.

[0043] The energy ray-curable resin contained in the adhesive composition may be only one kind or two or more kinds. When there are two or more kinds, their combinations and ratios can be arbitrarily selected. Further, it may be combined with the thermoplastic resin described later, and the combinations and ratios can be arbitrarily selected.

[0044] 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, examples of the adhesive include acrylic adhesives, urethane adhesives, rubber adhesives, polyester adhesives, silicone adhesives, and polyvinyl ether adhesives. Among these, it is preferable that the adhesive is at least any one selected from the group consisting of acrylic adhesives, urethane adhesives, and rubber adhesives, and more preferably an acrylic adhesive.

[0045] Examples of the acrylic adhesive include polymers containing structural units derived from alkyl (meth)acrylates having a linear alkyl group or a branched alkyl group (that is, polymers obtained by polymerizing at least alkyl (meth)acrylates), acrylic polymers containing structural units derived from (meth)acrylates having a cyclic structure (that is, polymers obtained by polymerizing at least (meth)acrylates having a cyclic structure), and the like. Here, “(meth)acrylate” is used as a term indicating both “acrylate” and “methacrylate”, and the same applies to other similar terms.

[0046] When the acrylic polymer is a copolymer, the form of copolymerization is not particularly limited. The acrylic copolymer may be any of a block copolymer, a random copolymer, or a graft copolymer.

[0047] When the acrylic polymer is a copolymer, the form of copolymerization is not particularly limited. The acrylic copolymer may be any of a block copolymer, a random copolymer, or a graft copolymer.

[0048] The acrylic copolymer may be crosslinked with a crosslinking agent. Examples of the crosslinking agent include known epoxy-based crosslinking agents, isocyanate-based crosslinking agents, aziridine-based crosslinking agents, metal chelate-based crosslinking agents, and the like. When crosslinking the acrylic copolymer, a hydroxyl group or a carboxyl group 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.

[0049] When the resin layer 3 is formed from an adhesive, the resin layer 3 may further contain the above-described energy ray curable resin in addition to the adhesive. When an acrylic adhesive is applied as the adhesive, a compound having both a functional group that reacts with a functional group derived from the monomer component in the acrylic copolymer and an energy ray polymerizable functional group in one molecule may be used as the energy ray curable component. By the reaction of the functional group of the compound with the functional group derived from the monomer component in the acrylic copolymer, the side chain of the acrylic copolymer becomes polymerizable by energy ray irradiation. Even when the adhesive is other than an acrylic adhesive, a component having a side chain that is similarly energy ray polymerizable may be used as a polymer component other than the acrylic polymer.

[0050] The thermosetting resin used for the resin layer 3 is not particularly limited, and specifically, epoxy resins, phenol resins, melamine resins, urea resins, polyester resins, urethane resins, acrylic resins, benzoxazine resins, phenoxy resins, amine-based compounds, and acid anhydride-based compounds, etc. can be mentioned. These can be used alone or in combination of two or more. Among these, from the viewpoint of being suitable for curing using an imidazole-based curing catalyst, it is preferable to use epoxy resins, phenol resins, melamine resins, urea resins, amine-based compounds, and acid anhydride-based compounds. In particular, from the viewpoint of exhibiting excellent curability, epoxy resins, phenol resins, mixtures thereof, or a mixture of an epoxy resin and at least one selected from the group consisting of phenol resins, melamine resins, urea resins, amine-based compounds, and acid anhydride-based compounds is preferably used.

[0051] The moisture-curable resin used for the resin layer 3 is not particularly limited, and examples thereof include urethane resins and modified silicone resins, which are resins that generate isocyanate groups upon exposure to moisture.

[0052] When using an energy ray-curable resin or a thermosetting resin, it is preferable to use a photoinitiator or a thermal polymerization initiator or the like. By using a photoinitiator or a thermal polymerization initiator or the like, a crosslinked structure can be formed, and it becomes possible to more strongly protect the pseudo-sheet structure 2.

[0053] Examples of the photoinitiator include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin benzoic acid methyl, 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.

[0054] Examples of the thermal polymerization initiator include hydrogen peroxide, peroxodisulfates (such as ammonium peroxodisulfate, sodium peroxodisulfate, and potassium peroxodisulfate), azo compounds (such as 2,2'-azobis(2-amidinopropane) dihydrochloride, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobisisobutyronitrile, and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile)), and organic peroxides (such as benzoyl peroxide, lauroyl peroxide, peracetic acid, succinic peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide).

[0055] These polymerization initiators can be used alone or in combination of two or more. When forming a crosslinked structure using these polymerization initiators, the amount used is preferably 0.1 part 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, based on 100 parts by mass of the energy ray curable resin or thermosetting resin.

[0056] The resin layer 3 may be a layer made of a thermoplastic resin composition, for example, which is not curable. And by containing a solvent in the thermoplastic resin composition, the thermoplastic resin layer can be softened. Thereby, when forming the pseudo-sheet structure 2 on the resin layer 3, it becomes easy to attach the conductive linear body 21 to the resin layer 3. On the other hand, by volatilizing the solvent in the thermoplastic resin composition, the thermoplastic resin layer can be dried and solidified.

[0057] 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 solvents, ketone solvents, ester solvents, ether solvents, hydrocarbon solvents, halogenated alkyl solvents, and water.

[0058] 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. Also, the thermal conductivity of the resin layer 3 is improved.

[0059] Examples of the inorganic filler include inorganic powders (for example, powders such as silica, alumina, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, and boron nitride), beads obtained by spheroidizing inorganic powders, single crystal fibers, and glass fibers. Among these, as the inorganic filler, silica filler and alumina filler are preferred. The inorganic filler may be used alone or in combination of two or more.

[0060] The resin layer 3 may contain other components. Examples of the other components include well-known additives such as organic solvents, flame retardants, tackifiers, ultraviolet absorbers, antioxidants, preservatives, fungicides, plasticizers, defoamers, and wettability modifiers.

[0061] The thickness of the resin layer 3 is appropriately determined according to the use of the wiring sheet 100. For example, from the viewpoint of adhesiveness, 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.

[0062] (Electrode) The electrode 4 is used to supply current to the conductive linear body 21. The electrode 4 can be formed using a known electrode material. Examples of the electrode material include conductive pastes (such as silver paste), metal foils (such as copper foil), and metal wires. The electrode 4 is disposed electrically connected to both ends of the conductive linear body 21. When the electrode material is a metal wire, the metal wire may be one, but preferably two or more. Examples of the metal of the metal foil or metal wire include metals such as copper, aluminum, tungsten, iron, molybdenum, nickel, titanium, silver, and gold, or alloys containing two or more metals (for example, steels such as stainless steel and carbon steel, brass, phosphor bronze, zirconium copper alloy, beryllium copper, iron nickel, nichrome, nickel titanium, kanthal, hastelloy, and rhenium tungsten). Also, the metal foil or metal wire may be plated with tin, zinc, silver, nickel, chromium, nickel chromium alloy, or solder. In particular, those containing one or more metals selected from copper and silver and alloys containing these are preferable from the viewpoint of metals with low volume resistivity.

[0063] The width of the electrode 4 is preferably 100 mm or less, more preferably 10 mm or less, and even more preferably 100 μm or less in a plan view of the pseudo-sheet structure 2. The narrower the width of the electrode 4, the more likely temperature unevenness is to occur. However, even when the width of the electrode 4 is narrow, according to the wiring sheet 100 according to the present embodiment, temperature unevenness can be suppressed. When the electrode 4 is a metal wire, the width of the electrode 4 is the diameter of the metal wire.

[0064] The ratio of the resistance value of the electrode 4 to the pseudo-sheet structure 2 (resistance value of the electrode 4 / resistance value of the pseudo-sheet structure 2) is preferably 0.0001 or more and 0.3 or less, and more preferably 0.0005 or more and 0.1 or less. The ratio of the resistance value of the electrode to the pseudo-sheet structure 2 can be obtained by "resistance value of the electrode 4 / resistance value of the pseudo-sheet structure 2". By being within this range, when the wiring sheet 100 is used as a heating element, abnormal heat generation at the electrode portion is suppressed. When the pseudo-sheet structure 2 is used as a sheet heater, only the pseudo-sheet structure 2 generates heat, and a sheet heater with good heat generation efficiency can be obtained. The resistance values of the electrode 4 and the pseudo-sheet structure 2 can be measured using a tester. First, measure the resistance value of the electrode 4, and then measure the resistance value of the pseudo-sheet structure 2 with the electrode 4 attached. Then, by subtracting the measured value of the electrode 4 from the resistance value of the pseudo-sheet structure 2 with the electrode attached, the resistance values of the electrode 4 and the pseudo-sheet structure 2 can be calculated respectively.

[0065] (Power supply section) The first power supply section 51 and the second power supply section 52 are portions for applying 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 first power supply section 51 or the second power supply section 52. In addition, in order to facilitate the connection of a power source (not shown) to the electrode 4, the first power supply portion 51 and the second power supply portion 52 may be separately provided. In this case, the same material as that of the electrode 4 can be used as the materials of the first power supply portion 51 and the second power supply portion 52. Further, when the electrode 4 is covered with an insulating material for preventing short circuit or the like, a portion where a part of the insulating material is removed may be used as the first power supply portion 51 and the second power supply portion 52.

[0066] (Manufacturing method of wiring sheet) The manufacturing method of the wiring sheet 100 according to the present embodiment is not particularly limited. The wiring sheet 100 can be manufactured, for example, by the following steps. First, a composition for forming the resin layer 3 is applied onto the base material 1 to form a coating film. Next, the coating film is dried to produce the resin layer 3. Next, while arranging the conductive linear bodies 21, they are disposed on the resin layer 3 to form the pseudo-sheet structure body 2. For example, while rotating the drum member with the resin layer 3 with the base material 1 disposed on the outer peripheral surface of the drum member, the conductive linear bodies 21 are spirally wound around the resin layer 3. Then, the bundle of the spirally wound conductive linear bodies 21 is cut along the axial direction of the drum member. Thereby, the pseudo-sheet structure body 2 is formed and disposed on the resin layer 3. Then, the resin layer 3 with the base material 1 on which the pseudo-sheet structure body 2 is formed is taken out from the drum member, and a sheet-like conductive member is obtained. According to this method, for example, by moving the feeding portion of the conductive linear bodies 21 along the direction parallel to the axis of the drum member while rotating the drum member, it is easy to adjust the interval L between the adjacent conductive linear bodies 21 in the pseudo-sheet structure body 2. Next, the electrode 4 is bonded to both ends of the conductive linear bodies 21 in the pseudo-sheet structure body 2 of the sheet-like conductive member, and then the first power supply portion 51 and the second power supply portion 52 are provided to produce the wiring sheet 100.

[0067] (Operation and effect of the first embodiment) According to the present embodiment, the following operation and effect can be achieved. (1) According to this embodiment, by satisfying the conditions shown in Formula (F2) and Formula (F3), the resistance value of the conductive linear body 21 decreases as it moves away from the first power supply unit 51 and the second power supply unit 52. Thereby, temperature unevenness in the wiring sheet 100 can be suppressed. (2) In this embodiment, since the length of the conductive linear body 21 becomes shorter as it moves away from the first power supply unit 51 and the second power supply unit 52, the resistance value of the conductive linear body 21 can be made lower as it moves away from the first power supply unit 51 and the second power supply unit 52. (3) Since the wiring sheet 100 according to this embodiment can suppress temperature unevenness, it can be suitably used as a sheet heater.

[0068] [Second Embodiment] Next, a second embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 3 and 4, the wiring sheet 100A according to this embodiment includes a base material 1, a pseudo-sheet structure body 2A, a resin layer 3, and a pair of electrodes 4. In the pseudo-sheet structure body 2A, a plurality of conductive linear bodies 21 are arranged at intervals. A first power supply unit 51 is provided on one electrode 4, and a second power supply unit 52 is provided on the other electrode 4. In this embodiment, since it is the same as the first embodiment except for the method of adjusting the resistance value of the conductive linear body 21, the method of adjusting the resistance value of the conductive linear body 21 will be described, and the parts common to the previous description other than that will be omitted.

[0069] In this embodiment, as shown in FIG. 4, the thicknesses of the conductive linear bodies 21 increase in the order of D1, D2, D3, and D4. That is, the thickness of the conductive linear body 21 becomes thicker as it moves away from the first power supply unit 51 and the second power supply unit 52, and the cross-sectional area of the conductive linear body 21 also becomes larger as it moves away from the first power supply unit 51 and the second power supply unit 52. In this way, the resistance value of the conductive linear body 21 can be made lower as it moves away from the first power supply unit 51 and the second power supply unit 52.

[0070] [Effects of the Second Embodiment] According to the present embodiment, in addition to the effects (1) and (3) in the first embodiment, the following effect (4) can be achieved. (4) In the present embodiment, since the thickness of the conductive linear body 21 is increased as it is farther from the first power supply portion 51 and the second power supply portion 52, the resistance value of the conductive linear body 21 can be lowered as it is farther from the first power supply portion 51 and the second power supply portion 52. And, as in the first embodiment, since it is not necessary to change the length of the conductive linear body 21, the planar shape of the wiring sheet 100A can be, for example, rectangular or square.

[0071] [Third Embodiment] Next, a third embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 5, the wiring sheet 100B according to the present embodiment includes a base material 1, two pseudo-sheet structures 2B, a resin layer 3, and two pairs of electrodes 4. In the pseudo-sheet structure 2B, a plurality of conductive linear bodies 21 are arranged at intervals. A first power supply portion 51 is provided on one of the electrodes 4, and a second power supply portion 52 is provided on the other electrode 4. Note that the wiring sheet 100B according to the present embodiment has a configuration in which two wiring sheets 100 according to the first embodiment are arranged side by side in a plan view of the wiring sheet 100. Since the base material 1, the pseudo-sheet structure 2B, the resin layer 3, and the electrode 4 are the same as those in the first embodiment, the arrangement of the two pseudo-sheet structures 2B will be described, and the portions common to the previous description other than that will be omitted.

[0072] In the present embodiment, as shown in FIG. 5, two wiring structures 10 including a pseudo-sheet structure 2B, a pair of electrodes 4, a first power supply portion 51, and a second power supply portion 52 are provided. The length of the conductive linear body 21 becomes shorter as it is farther from the first power supply portion 51 and the second power supply portion 52. Therefore, the planar shape of the wiring structure 10 is trapezoidal, and the side where the first power supply portion 51 and the second power supply portion 52 are located is long. And, in a plan view of the wiring sheet 100B, the two wiring structures 10 are arranged such that one wiring structure 10 and the other wiring structure 10 have opposite positions of the first power supply portion 51 and the second power supply portion 52.

[0073] (Effects of the Third Embodiment) According to the present embodiment, in addition to the effects (1) to (3) in the first embodiment, the following effect (5) can be achieved. (5) In the present embodiment, two wiring structures 10 having a trapezoidal planar shape are arranged in a plan view of the wiring sheet 100B such that the lower bases of the trapezoidal bases are on opposite sides of each other. In such a case, at both ends of the wiring sheet 100B, the lower base of one trapezoidal base and the upper base of the other trapezoidal base will exist. Therefore, the lengths of the wirings at both ends of the wiring sheet 100B can be made substantially equal, and the planar shape of the wiring sheet 100B can be made, for example, rectangular or square.

[0074] [Modifications of the Embodiment] The present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within the scope that can achieve the object of the present invention are included in 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 may not include the base material 1. In such a case, the resin layer 3 can be used to attach the wiring sheet 100 to an adherend for use. In the above-described embodiment, the wiring sheet 100 includes the resin layer 3, but is not limited thereto. For example, the wiring sheet 100 may not include the resin layer 3. In such a case, a knitted fabric may be used as the base material 1, and the conductive linear body 21 may be knitted into the base material 1 to form the pseudo-sheet structure 2.

Examples

[0075] Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples at all.

[0076] [Example 1] An acrylic adhesive was applied to a polyurethane film with a thickness of 100 μm as a base material to a thickness of 20 μm to provide a resin layer, and an adhesive sheet was produced. Using a wire injection device (manufactured by Rintec), a metal wire with a circular cross-section (material: tungsten, diameter: 80 μm) was injected onto this adhesive sheet while moving the nozzle, and the metal wires were arranged as conductive linear bodies. Subsequently, electrodes (width: 80 μm, material: copper) were provided at both ends of the metal wire, and then a first power supply part and a second power supply part (both made of copper) were provided on one end side of the electrode to obtain the wiring sheet shown in Fig. 1. The length of the first metal wire counted from the side of the first power supply part and the second power supply part was set to 200 mm, the length of the last metal wire was set to 120 mm, and the lengths of the metal wires were made to decrease sequentially from one side. In the obtained wiring sheet, the number N of metal wires was 30, the resistance value R of the electrode was 306 mΩ, the resistance value r1 of the metal wire was 25070 mΩ, and r2 to r 29 were successively lower by about 306 mΩ each, and r 30 was 16196 mΩ. Also, the interval between the metal wires was 10 mm.

[0077] [Comparative Example 1] A wiring sheet was produced in the same manner as in Example 1, except that the lengths of all the metal wires were set to 200 mm without changing the length of the metal wire. In the obtained wiring sheet, the number N of metal wires was 30, the resistance value R of the electrode was 306 mΩ, and the resistance values r1 to r 30 of the metal wires were all 25070 mΩ. Also, the interval between the metal wires was 10 mm.

[0078] [Temperature Difference Evaluation of Sheet Heater] After applying a voltage of 5.0 V to the sheet heater to cause it to generate heat, the temperature distribution was measured using a thermography camera ("FLIR C2" manufactured by FLIR) at a position 150 mm from the surface of the sheet heater. The emissivity at this time was set to 0.95 for measurement. The measurement results of the temperature distribution of the sheet heater obtained in Example 1 are shown in Fig. 6. Also, the measurement results of the temperature distribution of the sheet heater obtained in Comparative Example 1 are shown in Fig. 7. Then, the temperatures of the 30 wires were read from the obtained temperature distribution. The results are shown in FIG. 8. Further, the difference between the maximum temperature and the minimum temperature among the 28 wires excluding one wire at each end of the 30 wires was defined as the temperature difference (unit: °C). The smaller this temperature difference is, the more the temperature unevenness is suppressed. The temperature difference in Example 1 was 3.7 °C, and the temperature difference in Comparative Example 1 was 11.5 °C. From this result, it was found that according to the sheet heater obtained in Example 1, the temperature difference was smaller and the temperature unevenness could be suppressed as compared with the sheet heater obtained in Comparative Example 1.

[0079] [Confirmation of Operational Effects] According to the present embodiment, in order to confirm that a wiring sheet capable of suppressing temperature unevenness can be obtained, the analysis of the power consumption distribution described below was performed. In the analysis of the power consumption distribution, the wiring sheet according to the present embodiment was applied to a ladder-shaped circuit diagram, and the power consumption distribution in this circuit was analyzed. The number N of the conductive linear bodies 21, the resistance value r1 [mΩ] of the first conductive linear body 21 counted from the sides of the first power supply unit 51 and the second power supply unit 52, and the resistance value r of the Nth conductive linear body 21 counted from the sides of the first power supply unit 51 and the second power supply unit 52 N [mΩ], and the resistance value R [mΩ] of the electrode 4 were as shown in Tables 1 and 2. The values of r2 to r N-1 [mΩ] were gradually lowered at the same rate of change from the value of r1 to the value of r N . Also, the value [mΩ] of r1 - r N and the value [mΩ] of NR were also as shown in Tables 1 and 2. Then, when a current was passed through the above circuit, the power consumption of each conductive linear body from the first conductive linear body 21 to the Nth conductive linear body 21 was calculated, and the power consumption distribution was analyzed. From the obtained power consumption distribution, the maximum power consumption, the minimum power consumption, and the average power consumption were obtained, and the power unevenness (unit: ±%) was calculated based on the following calculation formula. For Examples 1 to 19, the obtained results are shown in Table 1. For Examples 20 to 37, the obtained results are shown in Table 2. (Power unevenness)=[{(Maximum power consumption)-(Minimum power consumption)} / (Average power consumption) / 2]×100 It is presumed that the smaller the power unevenness, the more the temperature unevenness is suppressed. Regarding the power unevenness, it was evaluated according to the following criteria. The results obtained for Examples 1 to 19 are shown in Table 1. The results obtained for Examples 20 to 37 are shown in Table 2. A: The numerical value of the power unevenness is 20 [±%] or less. B: The numerical value of the power unevenness exceeds 20 [±%] and is 30 [±%] or less. C: The numerical value of the power unevenness exceeds 30 [±%] and is 100 [±%] or less.

[0080]

Table 1

[0081]

Table 2

Explanation of symbols

[0082] 1…Base material, 2, 2A, 2B…Pseudo-sheet structure, 21…Conductive linear body, 3…Resin layer, 4…Electrode, 51…First power supply part, 52…Second power supply part, 100, 100A, 100B…Wiring sheet.

Claims

1. The device comprises a pseudo-sheet structure in which a plurality of conductive linear bodies are arranged at intervals, a pair of electrodes, and a first power supply portion and a second power supply portion provided on each of the electrodes, The number of the conductive linear bodies is N, and the resistance value of the n-th conductive linear body counted from the first power supply part and the second power supply part side is r ｎ and the resistance value of the electrode is R, all of the conditions shown in the following formula (F1), the following formula (F2), and the following formula (F3) are satisfied: Wiring sheet. r １ / R ≤ 300... (F1) r ｎ＋１ ≤ r ｎ ... (F2) (In the formula (F2), n is an integer of 1 or more.) NR / 8 ≤ r １ -r Ｎ ≤ NR... (F3)

2. The wiring sheet according to claim 1 , The intervals between the conductive linear bodies are 20 mm or less. Wiring sheet.

3. The wiring sheet according to claim 1 or 2, In a plan view of the pseudo sheet structure, the width of the electrode is 100 mm or less. Wiring sheet.

4. The wiring sheet according to any one of claims 1 to 3, Further, a substrate is provided to support the pseudo-sheet structure. Wiring sheet.

5. A wiring sheet comprising the wiring sheet according to any one of claims 1 to 4. Sheet heater.

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