JP2024052337A - Wiring sheet and sheet heater - Google Patents

Abstract

[Problem] To provide a wiring sheet with a high degree of freedom in design. [Solution] A wiring sheet 100 comprising a pseudo sheet structure 2 in which a plurality of conductive linear bodies 21 are arranged at intervals, and a pair of electrodes 4, in which at least one of the conductive linear bodies 21 differs from the other one in at least one of the material, surface layer material, diameter, and wavy shape in plan view. [Selected Figure] Figure 1

Description

The present invention relates to a wiring sheet and a sheet-shaped heater.

As an example of a wiring sheet that can be used for a sheet heater, 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.
When commercializing such a sheet heater, it is necessary to match the specifications of the wiring sheet, such as the resistance value, the spacing between the linear members, etc. However, when designing a wiring sheet using a single type of linear member, there is a problem that the design is difficult because there is a limit to the types of linear members available on the market.

International Publication No. 2017/086395

The object of the present invention is to provide a wiring sheet and a sheet heater that offer high design freedom.

[1] A pseudo sheet structure having a plurality of conductive linear bodies arranged at intervals and a pair of electrodes,
At least one of the conductive linear bodies is different from the other one in at least one of a material, a surface layer material, a diameter, and a wavy shape in a plan view.
Wiring sheet.

[2] The wiring sheet according to [1],
the conductive linear body is of three or more types,
Three or more types of conductive linear bodies are periodically arranged.
Wiring sheet.

[3] The wiring sheet according to [2],
One of the three or more types of conductive linear bodies has a material or a surface layer material different from that of the other types,
The conductive linear bodies are spaced apart from each other by 1.5 mm or less.
Wiring sheet.

[4] A wiring sheet according to any one of [1] to [3],
Sheet heater.

According to one aspect of the present invention, it is possible to provide a wiring sheet and a sheet-shaped heater that have a high degree of design freedom.

1 is a schematic diagram showing a wiring sheet according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the II-II cross section of FIG.

[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)
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 members 21 arranged at intervals.
At least one of the conductive linear bodies 21 is different from the other one in at least one of the material, surface layer material, diameter, and wavy shape in plan view. Specifically, as shown in Figures 1 and 2, two types of conductive linear bodies 21 having different diameters are arranged alternately with a periodicity.

The inventors surmise that the reason why wiring sheet 100 according to the present embodiment increases the degree of freedom in design is as follows.
That is, in the case of using a single type of conductive linear body 21 as in the past, the resistance value of the pseudo sheet structure 2 was adjusted by changing the material, surface layer material, diameter, etc. of the conductive linear body 21 itself, or by changing the number of the conductive linear body 21. However, since the types of the conductive linear body 21 are limited, it was difficult to adjust the resistance value to a desired value. In contrast, in the present embodiment, the resistance value of the pseudo sheet structure 2 can be adjusted by using, for example, two types of conductive linear body 21 in half each. In addition, the resistance value of the pseudo sheet structure 2 can be adjusted by using, for example, two types of conductive linear body 21 in a ratio of 2:1. In this way, the resistance value of the pseudo sheet structure 2 can be adjusted more freely by simply using two types of conductive linear body 21. Note that if the two types of conductive linear body 21 are arranged with a periodicity, there is almost no problem with the appearance of the wiring sheet 100. In this way, the degree of freedom in design is increased.

In this embodiment, for example, the conductive linear objects 21 may be made of different materials.
The resistance value per unit length of the conductive linear body 21 can be changed depending on the material by changing the material. For example, the higher the volume resistivity of a material used, the higher the resistance value per unit length of the conductive linear body 21.

The surface layer materials of any of the conductive linear bodies 21 may be different from each other.
The resistance value per unit length of the conductive linear body 21 can be changed according to the type of surface layer material by changing the type of surface layer material. For example, the lower the volume resistivity of the surface layer material used, the lower the resistance value per unit length of the conductive linear body 21.

The diameters of any of the conductive linear objects 21 may be different.
Since changing the diameter changes the cross-sectional area, the resistance value per unit length of the conductive linear body 21 can be changed according to the diameter. For example, the larger the diameter of the conductive linear body 21, the lower the resistance value per unit length of the conductive linear body 21.

The wavy shape in a plan view may be different between any two adjacent conductive linear objects 21 .
The resistance value of the conductive linear body 21 between the electrodes 4 can be changed according to the waveform, wavelength, amplitude, etc., because changing the wave shape (waveform, wavelength, amplitude, etc.) in a plan view changes the length of the conductive linear body 21. For example, the shorter the wavelength and the larger the amplitude, the higher the resistance value of the conductive linear body 21 between the electrodes 4.

In this embodiment, at least one of the material, surface material, diameter, and wavy shape in plan view of the conductive linear body 21 may be adjusted as appropriate. Two or more of these may also be adjusted in combination.

In this embodiment, the conductive linear members 21 are of three or more types, and it is preferable that the three or more types of conductive linear members are arranged periodically.
In this way, the degree of freedom in design can be further increased by using three or more types of conductive linear bodies 21. Furthermore, by arranging conductive linear bodies 21 with a periodicity, there is almost no problem with the appearance of wiring sheet 100.

In addition, in this embodiment, it is preferable that one type of the three or more types of conductive linear bodies 21 has a material or surface layer material different from the other types, and that the spacing L between the conductive linear bodies 21 is 2.0 mm or less.
By changing the material or surface layer material, the resistance value of the conductive linear body 21 itself can be changed considerably. For example, if one type of material is carbon nanotubes and the other type of material is metal, the difference in resistance value between carbon nanotubes and metal is considerably large, so that the conductive linear body 21 made of carbon nanotubes generates almost no heat when a current is passed through the wiring sheet 100. In this way, a pseudo sheet structure 2 having dummy conductive linear bodies 21 that generate almost no heat can be obtained. The number of conductive linear bodies 21 can also be increased without changing the resistance value of the pseudo sheet structure 2 as a whole.
In addition, from the relationship between the visibility of the conductive linear body 21 and the spatial frequency characteristics of the human eye, it has been found that when the interval L of the conductive linear body 21 is 2.5 mm or more, the conductive linear body 21 becomes very easy to see. On the other hand, when the interval of the conductive linear body 21 is 2.0 mm or less, there is a phenomenon that the conductive linear body 21 becomes difficult to see. From the same viewpoint, the interval of the conductive linear body 21 is more preferably 1.5 mm or less, and particularly preferably 1.0 mm or less. It is usually preferable that the conductive linear body 21 is difficult to see, and in this case, it is also said that the visibility of the conductive linear body 21 is good. In this embodiment, the number of the conductive linear body 21 can be increased and the interval of the conductive linear body 21 can be adjusted without changing the resistance value of the pseudo sheet structure 2. Therefore, the conductive linear body 21 can be made difficult to see without changing the resistance value of the pseudo sheet structure 2.
Moreover, the interval L between the conductive linear members 21 is preferably 0.05 mm or more, more preferably 0.1 mm or more, and particularly preferably 0.3 mm or more. By setting the interval L between the conductive linear members 21 to the above value, it is possible to prevent adjacent conductive linear members 21 from contacting each other.

The distance L between the conductive linear members 21 is measured, for example, 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.

(Base material)
The base material 1 can directly or indirectly support the pseudo sheet structure 2. The base material 1 is not necessarily required. The base material 1 is a member that is provided as necessary.
Examples of the substrate 1 include a resin film, paper, a nonwoven fabric, a cloth, and a glass film. The substrate 1 may be transparent or may have visibility. In this way, the wiring sheet 100 can be made transparent or have visibility. The substrate 1 may also have elasticity. For example, if the substrate 1 has elasticity, the elasticity of the wiring sheet 100 can be ensured even when the pseudo sheet structure 2 is provided on the substrate 1.
The substrate 1 may be a resin film, a nonwoven fabric, a cloth, or the like.
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, polystyrene films, polycarbonate films, and polyimide films. Other 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.
There is no particular limitation on the thickness of the substrate 1. The thickness of the substrate 1 is preferably 10 μm or more and 10 mm or less, more preferably 15 μm or more and 5 mm or less, and even more preferably 50 μm or more and 3 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 each other. The pseudo sheet structure 2 also 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 bodies 21.

The conductive linear body 21 may be linear in a plan view of the wiring sheet 100, but may also be wavy. Examples of the wave shape include a sine wave, a rectangular wave, a triangular wave, and a sawtooth wave. For example, 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 was measured as follows: Silver paste was applied to the ends of the conductive linear body 21 and to a section 40 mm from the ends, and the resistance of the ends and the section 40 mm from the ends was measured. The volume resistivity of the conductive linear body 21 was 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 viewpoint of compatibility with the resin layer 3, etc., it is preferable that the cross-sectional shape of the conductive linear body 21 is elliptical or circular.

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 3 μm or more and 200 μm or less. From the viewpoints of suppressing an increase in sheet resistance and improving the heat generation efficiency and dielectric breakdown resistance characteristics of the wiring sheet 100, the diameter D of the conductive linear body 21 is more preferably 4 μm or more and 150 μm or less, and further preferably 5 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 diameter D described above.

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

The conductive linear body 21 may be any form, but may be a linear body including a metal wire (hereinafter also referred to as a "metal wire linear body"). Metal wire has high thermal conductivity, high electrical conductivity, and high handling properties. The metal wire linear body can greatly reduce resistance, and even if the diameter of the metal wire linear body is extremely small, it can pass a current required for heating the wiring sheet 100. This makes it possible to make the conductive linear body 21 less visible. That is, 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 the light transmittance is easily improved. In addition, the wiring sheet 100 is easily able to generate heat quickly. 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 metal wires 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, which will be described later. In particular, wires containing one or more metals selected from tungsten and molybdenum, and alloys containing these, are preferred from the viewpoint of 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 coats the metal wire include amorphous carbon (for example, 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, and alloys containing at least one of these metal elements (such as copper-nickel-phosphorus alloy and copper-iron-phosphorus-zinc alloy).

The conductive linear body 21 may be a linear body having a conductive coating applied to the thread. Examples of the thread include threads spun from resins such as nylon or polyester. Examples of the thread include threads such as metal fibers, carbon fibers, or ion-conductive polymer fibers. Examples of the conductive coating include coatings of metals, conductive polymers, or carbon materials. The conductive coating can be formed by plating, vapor deposition, or the like. A linear body having a conductive coating 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 supported directly or indirectly by this resin layer 3. The resin layer 3 is not necessarily provided. The resin layer 3 is a member that is provided as necessary. The resin layer 3 is preferably a layer containing an adhesive. For example, when forming the pseudo sheet structure 2 on the resin layer 3, the adhesive makes it easy to attach the conductive linear body 21 to the resin layer 3.

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 can suppress deformation of the wiring sheet 100 due to impact.

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 contained in the resin layer 3 may be a thermosetting adhesive that hardens when heated, a so-called heat seal type adhesive 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 or more and 30,000 or less, and more preferably 300 or more and 10,000 or less.

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 is 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.

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

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 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.

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 curable by energy ray irradiation. Even when the adhesive is other than an acrylic adhesive, a component whose side chain is polymerizable with energy rays 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, and acid anhydride-based compound. 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-curing resin used in the resin layer 3 is not particularly limited, and examples include moisture-curing urethane resin, which is a resin in which isocyanate groups are generated by moisture, and modified silicone resin.

When an energy ray curable resin is used as the resin used in the resin layer 3, it is preferable to use a photopolymerization initiator or the like. When a thermosetting resin is used as the resin used in the resin layer 3, it is preferable to use a thermal polymerization initiator or the like. By using a photopolymerization initiator, a thermal polymerization initiator, or the like in the resin layer 3, a crosslinked structure is formed in the resin layer 3, 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 forming a crosslinked structure using these polymerization initiators, 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 even more preferably 1 part by mass or more and 10 parts by mass or less, relative to 100 parts by mass of at least any one of the energy ray curable resin and 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, for example, 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.

Examples of inorganic fillers include inorganic powders (e.g., powders of silica, alumina, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, 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 determined according to 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 a pair. 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.
The electrode 4 can be formed using a known electrode material. Examples of the electrode material include a conductive paste (such as silver paste), a metal foil (such as copper foil), and a metal wire. When the electrode material is a metal wire, the number of metal wires may be one, but is preferably two or more.

When the electrode material is a metal foil or metal wire, examples of the metal of the metal foil or metal wire include 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 alloy, beryllium copper, iron nickel, nichrome, nickel titanium, Kanthal, Hastelloy, and rhenium tungsten, etc.). The metal foil or metal wire may be plated with gold, tin, zinc, silver, nickel, chromium, nickel chromium alloy, solder, etc.

The width of at least one of the electrodes 4 is preferably 10 mm or less, more preferably 3000 μm or less, and even more preferably 1500 μm or less, in a plan view of the wiring sheet 100. The width of this electrode is preferably 0.1 mm or more. Note that when at least one of the electrodes is a metal wire, the width of the electrode is the diameter of the metal wire, and when two or more metal wires are used, the width of one electrode refers to the sum of the diameters of the metal wires.

The thickness of the electrode 4 is preferably 2 μm or more and 200 μm or less, more preferably 2 μm or more and 170 μm or less, and even more preferably 10 μm or more and 150 μm or less. If the thickness of the electrode 4 is within the above range, the electrical conductivity is high and the resistance is low, and the resistance value with the pseudo sheet structure can be kept low. In addition, sufficient strength as an electrode is obtained. Note that, when the electrode is a metal wire, the thickness of the electrode is the diameter of the metal wire.

(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 wound around the resin layer 3 while rotating the drum member. Here, at least one of the conductive linear bodies 21 is different from the other one in at least one of the material, the surface layer material, the diameter, and the wavy shape in a plan view. Then, the bundle of the 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, it is easy to adjust the spacing L between adjacent conductive linear bodies 21 in the pseudo sheet structure 2 by rotating the drum member and moving the payout portion of the conductive linear body 21 along a direction parallel to the axis of the drum member.
Next, electrodes 4 are formed on both ends of the conductive linear members 21 in the pseudo sheet structure 2 of the sheet-like conductive member. In this manner, the wiring sheet 100 can be produced.

(Effects of the embodiment)
According to this embodiment, the following advantageous effects can be obtained.
(1) According to this embodiment, by using two or more types of conductive linear bodies 21 that differ in at least one of the material, surface material, diameter, and wavy shape in a planar view, the resistance value of the pseudo sheet structure 2 can be adjusted more freely.
(2) The wiring sheet 100 according to the present embodiment has a high degree of freedom in design and can therefore be suitably used as a sheet-type heater.

[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 adhesive sheet (140 mm x 100 mm) was wound around a rubber drum without wrinkles, with one adhesive side facing outward, and both ends in the circumferential direction were fixed with double-sided tape. Various conductive linear bodies wound around a bobbin were attached to the surface of the adhesive sheet located near the end of the rubber drum, and then wound around the rubber drum while unwinding the conductive linear bodies in the following arrangement at intervals of 2 mm, and the rubber drum was gradually moved in a direction parallel to the drum axis so that the conductive linear bodies were wound around the rubber drum while drawing a spiral at regular intervals. The adhesive sheet was cut along with the conductive linear bodies parallel to the drum axis to obtain a sheet in which a pseudo-sheet structure in which conductive linear bodies were arranged was laminated on the adhesive sheet. Thereafter, the conductive linear bodies were attached to an electrode sheet prepared in advance, which was made of a polycarbonate film printed with silver paste ("XA-3676" manufactured by Fujikura Kasei Co., Ltd.), so that the number of conductive linear bodies was 10, to obtain a sheet-like heater. The silver paste electrodes were fabricated to have a thickness of 18 μm, a width of 5 mm, and an inter-electrode distance of 120 mm.
(Arrangement of Conductive Linear Bodies)
Repeat of the first and second wires below: First wire: Tungsten wire, diameter 9 μm, resistance per unit length 10.5 Ω/cm
- Second wire: tungsten wire, diameter 11 μm, resistance per unit length 7.1 Ω/cm

[Example 2]
A sheet-type heater was produced in the same manner as in Example 1, except that the conductive linear bodies were arranged as follows:
(Arrangement of Conductive Linear Bodies)
Repeat from the first to fifth wires as follows: 1st wire: Tungsten wire, diameter 8 μm, resistance per unit length 13.3 Ω/cm
- Second wire: tungsten wire, diameter 8 μm, resistance per unit length 13.3 Ω/cm
・3rd wire: Silver-plated rhenium tungsten wire, diameter 14 μm,
Resistance per unit length: 5.2 Ω/cm
4th wire: tungsten wire, diameter 8 μm, resistance per unit length 13.3 Ω/cm
5th wire: Silver-plated rhenium tungsten wire, diameter 14 μm, resistance per unit length 5.2 Ω/cm

[Example 3]
A sheet-type heater was produced in the same manner as in Example 1, except that the conductive linear bodies were arranged as follows:
(Arrangement of Conductive Linear Bodies)
1st to 4th wires: gold-plated tungsten wire, diameter 10 μm, resistance per unit length 7.7 Ω/cm
・5th and 6th wires: gold-plated tungsten wire, diameter 8 μm, resistance per unit length 12.5 Ω/cm
7th to 10th wires: gold-plated tungsten wire, diameter 10 μm, resistance per unit length 7.7 Ω/cm
In addition, by arranging a conductive linear body with high resistivity in the center as in this sheet heater, it is possible to reduce uneven heating at high temperatures. In other words, if the temperature of the entire heater is relatively higher than the required temperature, the central part may be affected by the surrounding heated parts and may become overheated. In that case, it is preferable to arrange a conductive linear body with high resistance in the center as in this embodiment. By using a conductive linear body with high resistance and reducing the power in the center, it is possible to lower the temperature in the center and prevent overheating.

[Example 4]
A sheet-type heater was produced in the same manner as in Example 1, except that the conductive linear bodies were arranged as follows:
(Arrangement of Conductive Linear Bodies)
1st to 9th wires: gold-plated tungsten wire, diameter 10 μm, resistance per unit length 7.7 Ω/cm
10th wire: gold-plated tungsten wire, diameter 8 μm, resistance per unit length 12.5 Ω/cm
In addition, by arranging conductive linear bodies with high resistivity at the ends as in this sheet heater, uneven heating at low temperatures can be reduced. In other words, when the temperature of the entire heater is relatively lower than the required temperature, the approach as in Example 3 is not necessary, and it is preferable to arrange conductive linear bodies with high resistance at the ends. The center can be heated sufficiently, and by arranging conductive linear bodies for adjusting the resistance at the ends that are not required as heating areas, it is possible to control the total resistance of the entire heater and the temperature distribution of the heating areas.

[Example 5]
A sheet-type heater was produced in the same manner as in Example 1, except that the conductive linear bodies were arranged as follows:
(Arrangement of Conductive Linear Bodies)
Repeat of the first and second wires below: First wire: Tungsten wire, diameter 11 μm, resistance per unit length 7.1 Ω/cm
- Second wire: Tungsten wire, diameter 11 μm, resistance per unit length 7.1 Ω/cm, wavy shape in plan view (sine wave with wavelength 5 mm and total amplitude 2 mm)

[Example 6]
A sheet-type heater was produced in the same manner as in Example 1, except that the conductive linear bodies were arranged as shown below, the intervals between the conductive linear bodies were 1 mm, and the number of the conductive linear bodies was 20.
(Arrangement of Conductive Linear Bodies)
Repeat the following from the first to fourth wires: 1st wire: tungsten wire, diameter 9 μm, resistance per unit length 10.5 Ω/cm
- 2nd: CNT yarn, diameter 10 μm, resistance per unit length 450 Ω/cm
- Third wire: tungsten wire, diameter 11 μm, resistance per unit length 7.1 Ω/cm
4th: CNT yarn, diameter 10 μm, resistance per unit length 450 Ω/cm

[Comparative Example 1]
A sheet-shaped heater was produced in the same manner as in Example 1, except that only one type of conductive linear body (material: tungsten, diameter: 11 μm, resistance per unit length: 7.1 Ω/cm) was used.

[Comparative Example 2]
A sheet-shaped heater was produced in the same manner as in Example 1, except that only one type of conductive linear body (material: tungsten, diameter: 9 μm, resistance per unit length: 10.5 Ω/cm) was used.

[Resistance value of sheet heater]
The terminals of a resistance meter "RM3545" manufactured by Hioki E.E. Corporation were brought into contact with the electrodes made of silver paste to measure the resistance of the sheet heater. Then, the ratio [(measured value - 10)/10 x 100] (unit: %) to the target value of 10 Ω for each example was calculated. The results are shown in Table 1. The type of conductive linear body in each example is also shown in Table 1.

[Visibility of conductive linear object]
When the sheet heater is viewed from a distance of 100 cm, it is evaluated whether the conductive linear bodies can be recognized. The evaluation was carried out by five people, and visibility was evaluated according to the following criteria. The results are shown in Table 1. The spacing between the conductive linear bodies in each example is also shown in Table 1.
A: No one was able to recognize the conductive linear object.
B: One or two people were able to recognize the conductive linear object.
F: Three or more people were able to recognize the conductive linear object.

From the results shown in Table 1, when at least one of the conductive linear bodies was different from the other one in at least one of the following characteristics (material, surface material, diameter, and wavy shape in plan view) (Examples 1 to 3), the resistance value of the sheet-type heater could be made closer to the target value compared to when only the same conductive linear bodies were used (Comparative Examples 1 and 2). This confirmed that the sheet-type heaters obtained in Examples 1 to 3 have a high degree of freedom in design.

1...substrate, 2...pseudo sheet structure, 21...conductive linear body, 3...resin layer, 4...electrode, 100...wiring sheet.

Claims (4)

A pseudo sheet structure in which a plurality of conductive linear bodies are arranged at intervals, and a pair of electrodes are provided,
At least one of the conductive linear bodies is different from the other one in at least one of a material, a surface layer material, a diameter, and a wavy shape in a plan view.
Wiring sheet. The wiring sheet according to claim 1 ,
the conductive linear body is of three or more types,
Three or more types of conductive linear bodies are periodically arranged.
Wiring sheet. The wiring sheet according to claim 2,
One of the three or more types of conductive linear bodies has a material or a surface layer material different from that of the other types,
The conductive linear bodies are spaced apart from each other by 1.5 mm or less.
Wiring sheet. The wiring sheet according to any one of claims 1 to 3,
Sheet heater.

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