WO2024204434A1

WO2024204434A1 - Layered body

Info

Publication number: WO2024204434A1
Application number: PCT/JP2024/012440
Authority: WO
Inventors: 拓也大嶋; 雅春伊藤
Original assignee: リンテック株式会社
Priority date: 2023-03-29
Filing date: 2024-03-27
Publication date: 2024-10-03

Abstract

A layered body (100) comprising a first substrate (1), a second substrate (2) that has a higher coefficient of linear expansion than the first substrate (1), and a wiring sheet (10) that is sandwiched between the first substrate (1) and the second substrate (2), wherein the wiring sheet (10) comprises a wiring body (3) in which a plurality of conductive linear bodies (31) are arranged at intervals, a first resin layer (4) that directly or indirectly supports the wiring body (3), and a pair of electrodes (5) that are in direct contact with the conductive linear bodies (31), and the first substrate (1) or second substrate (2) and the wiring sheet (10) are layered with a second resin layer (6) that has a lower storage modulus than the first resin layer (4) interposed therebetween.

Description

Laminate

The present invention relates to a laminate.

For example, Patent Document 1 discloses a wiring sheet that can be used for a sheet heater, which includes a pseudo-sheet structure in which a plurality of conductive linear members are arranged at intervals, a cured material layer that supports the pseudo-sheet structure, and a pair of electrodes in direct contact with the conductive linear members. In this wiring sheet, the cured material layer is made of a cured product of a curable adhesive, and the storage modulus of the cured material layer at 23° C. is 5.0× ¹⁰ Pa or more and 1.0× ¹⁰ Pa or less.

International Publication No. 2021/225142

The wiring sheet described in Patent Document 1 can stabilize the resistance value of the wiring. However, it has been found that when the wiring sheet described in Patent Document 1 is used by placing it between two substrates with different linear expansion coefficients, cracks may occur in one of the substrates.

The object of the present invention is to provide a laminate that can prevent cracks from occurring in the substrate.

[1] A laminate including a first substrate, a second substrate having a linear expansion coefficient higher than that of the first substrate, and a wiring sheet sandwiched between the first substrate and the second substrate,
the wiring sheet includes a wiring body in which a plurality of conductive linear bodies are arranged at intervals, a first resin layer that directly or indirectly supports the wiring body, and a pair of electrodes that directly contact the conductive linear bodies,
The first substrate or the second substrate and the wiring sheet are laminated via a second resin layer having a storage modulus lower than that of the first resin layer.
Laminate.

[2] The laminate according to [1],
The second resin layer has a storage modulus at 23° C. of 1.0×10 ⁴ Pa or more and 3.0×10 ⁵ Pa or less.
Laminate.

[3] The laminate according to [1] or [2],
The storage modulus of the first resin layer at 23° C. is 5.0×10 ⁶ Pa or more and 1.0×10 ¹⁰ Pa or less.
Laminate.

[4] The laminate according to any one of [1] to [3],
The linear expansion coefficient of the first substrate is 0.01×10 ⁻⁶ /° C. or more and 10×10 ⁻⁶ /° C. or less.
Laminate.

[5] The laminate according to any one of [1] to [4],
The linear expansion coefficient of the second base material is 50×10 ⁻⁶ /° C. or more and 100×10 ⁻⁶ /° C. or less.
Laminate.

[6] The laminate according to any one of [1] to [5],
The second base material and the wiring sheet are laminated via the second resin layer.
Laminate.

According to one aspect of the present invention, a laminate can be provided that can prevent cracks from occurring in the substrate.

1 is a schematic diagram showing a laminate according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the II-II cross section of FIG. FIG. 4 is a cross-sectional view showing a cross section of a laminate according to a second embodiment of the present invention.

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

(Laminate)
As shown in Figures 1 and 2, the laminate 100 of this embodiment comprises a first substrate 1, a second substrate 2 having a higher linear expansion coefficient than the first substrate 1, and a wiring sheet 10 sandwiched between the first substrate 1 and the second substrate 2.
The wiring sheet 10 includes a wiring body 3 having a plurality of conductive linear bodies 31 arranged at intervals, a first resin layer 4 that directly or indirectly supports the wiring body 3, and a pair of electrodes 5 that are in direct contact with the conductive linear bodies 31.
Moreover, the first substrate 1 or the second substrate 2 and the wiring sheet 10 are laminated via a second resin layer 6 having a lower storage modulus than the first resin layer 4. In Fig. 2, the second substrate 2 and the wiring sheet 10 are laminated via the second resin layer 6.
The second substrate 2 has two holes formed therein, and these two holes can electrically connect the pair of electrodes 5 to a power source (not shown).

The inventors surmise that the reason why the laminate 100 according to this embodiment can prevent cracks from occurring in the substrate is as follows.
That is, the reason why cracks occur in the second substrate 2 is because the linear expansion coefficients are different between the first substrate 1 and the second substrate 2. For example, when the laminate 100 becomes hot, the second substrate 2 expands more than the first substrate 1. Since the first substrate 1 and the second substrate 2 are fixed by the wiring sheet 10 sandwiched between them, distortion occurs in the second substrate 2, and cracks occur. In contrast, in this embodiment, the first substrate 1 or the second substrate 2 and the wiring sheet 10 are laminated via the second resin layer 6, which has a lower storage modulus than the first resin layer 4. The second resin layer 6 is easily deformed because of its low storage modulus. Therefore, when the laminate 100 becomes hot, the second resin layer 6 deforms, and the distortion occurring in the second substrate 2 can be alleviated. In this way, it is possible to prevent cracks from occurring in the substrate.

(First substrate)
First substrate 1 can directly or indirectly support wiring body 3. In addition, first substrate 1 can protect one surface of wiring sheet 10.
The linear expansion coefficient of the first base material 1 is lower than the linear expansion coefficient of the second base material 2. Thus, even if there is a difference in the linear expansion coefficient, according to this embodiment, the occurrence of cracks in the second base material 2 can be prevented.
The linear expansion coefficient of the first substrate 1 may be 0.01×10 ⁻⁶ /° C. or more, 0.1×10 ⁻⁶ /° C. or more, or 0.5×10 ⁻⁶ /° C. or more. The linear expansion coefficient of the first substrate 1 is preferably 20×10 ⁻⁶ /° C. or less, more preferably 10×10 ⁻⁶ /° C. or less, and particularly preferably 5×10 ⁻⁶ /° C. or less. The linear expansion coefficient can be measured by the method described in the examples below. The conditions for measuring the linear expansion coefficient are as described below.

The material of the first substrate 1 is preferably resin, glass, or the like, from the viewpoints of strength and handling properties of the laminate.
When the first substrate 1 is in the form of a film, the thickness of the first substrate 1 is not particularly limited. The thickness of the first substrate 1 is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 50 μm or more. The thickness of the first substrate 1 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less.

(Second substrate)
Second substrate 2 can directly or indirectly support wiring body 3. In addition, second substrate 2 can protect one surface of wiring sheet 10.
The linear expansion coefficient of the second substrate 2 is higher than the linear expansion coefficient of the first substrate 1. Thus, even if there is a difference in the linear expansion coefficient, according to this embodiment, the occurrence of cracks in the second substrate 2 can be prevented.
The linear expansion coefficient of the second base material 2 is preferably 30×10 ^-6 /° C. or more, more preferably 45×10 ^-6 /° C. or more, and even more preferably 60×10 ^-6 /° C. or more. The linear expansion coefficient of the second base material 2 is preferably 200×10 ^-6 /° C. or less, more preferably 150×10 ^-6 /° C. or less, and even more preferably 100×10 ^-6 /° C. or less. The method for measuring the linear expansion coefficient is as described below.

The material of the second base material 2 is preferably a resin or the like from the viewpoints of the handleability of the laminate and suitability for production.
Examples of the resin include polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyurethane, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, polystyrene, polycarbonate, cycloolefin polymer, and polyimide.

When the second substrate 2 is in the form of a film, the thickness of the second substrate 2 is not particularly limited. The thickness of the second substrate 2 is preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more. The thickness of the second substrate 2 is preferably 10 mm or less, more preferably 5 mm or less, and even more preferably 3 mm or less.

(Wiring sheet)
The wiring sheet 10 includes a wiring body 3, a first resin layer 4, and a pair of electrodes 5. The wiring sheet 10 is sandwiched between a first substrate 1 and a second substrate 2, and both surfaces of the wiring sheet 10 are protected by the first substrate 1 and the second substrate 2.

(Wiring body)
The wiring body 3 has a structure in which a plurality of conductive linear bodies 31 are arranged at intervals from one another. The wiring body 3 also has a structure in which a plurality of conductive linear bodies 31 are arranged in parallel.

The conductive linear body 31 may be linear in a plan view of the laminate 100, but may also be wavy. Examples of wave shapes include a sine wave, a rectangular wave, a triangular wave, and a sawtooth wave. For example, if the wiring body 3 has such a structure, breakage of the conductive linear body 31 can be suppressed when the laminate 100 is stretched in the axial direction of the conductive linear body 31.

The volume resistivity of the conductive linear body 31 is preferably 1.0×10 ^-9 Ω·m or more, more preferably 3.0×10 ^-9 Ω·m or more, and even more preferably 1.0×10 ^-8 Ω·m or more. The volume resistivity of the conductive linear body 31 is preferably 1.0×10 ^-3 Ω·m or less, more preferably 1.0×10 ^-4 Ω·m or less, and even more preferably 1.0×10 ^-5 Ω·m or less. When the volume resistivity of the conductive linear body 31 is in the above range, the surface resistance of the wiring body 3 is likely to decrease.
The volume resistivity of the conductive linear body 31 was measured as follows: Silver paste was applied to the ends of the conductive linear body 31 and to a portion 40 mm from the ends, and the resistance of the ends and the portion 40 mm from the ends was measured. The volume resistivity of the conductive linear body 31 was then calculated by multiplying the resistance value by the cross-sectional area (unit: ^m2 ) of the conductive linear body 31 and dividing the obtained value by the measured length (0.04 m).

The cross-sectional shape of the conductive linear body 31 is not particularly limited, and may be polygonal, flat, elliptical, circular, or the like. From the standpoint of compatibility with the first resin layer 4, etc., it is preferable that the cross-sectional shape of the conductive linear body 31 is elliptical or circular.

When the cross section of the conductive linear body 31 is circular, the diameter D (see FIG. 2) of the conductive linear body 31 is preferably 3 μm or more and 200 μm or less. From the viewpoint of suppressing an increase in sheet resistance and improving the heat generation efficiency and dielectric breakdown resistance characteristics of the laminate 100, the diameter D of the conductive linear body 31 is more preferably 4 μm or more, and even more preferably 5 μm or more. The diameter D of the conductive linear body 31 is more preferably 150 μm or less, even more preferably 100 μm or less, particularly preferably 50 μm or less, and extremely preferably 20 μm or less.
When the cross section of the conductive linear body 31 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 31 is determined by observing the conductive linear body 31 using a digital microscope, measuring the diameter of the conductive linear body 31 at five randomly selected points, and averaging the measured values.

The interval L (see FIG. 2 ) between the conductive linear members 31 is preferably 0.3 mm or more, more preferably 0.5 mm or more, even more preferably 0.8 mm or more, and particularly preferably 1.5 mm or more. The interval L between the conductive linear members 31 is preferably 50 mm or less, more preferably 30 mm or less, even more preferably 20 mm or less, and particularly preferably 5 mm or less.
If the spacing between the conductive linear bodies 31 is within the above range, the conductive linear bodies are relatively densely packed, which improves the functionality of the laminate 100, such as maintaining the resistance of the wiring body 3 low.

The distance L between the conductive linear members 31 is measured by, for example, observing the conductive linear members 31 of the wiring body 3 using a digital microscope and measuring the distance between two adjacent conductive linear members 31 .
The interval between two adjacent conductive linear bodies 31 is the length along the direction in which the conductive linear bodies 31 are arranged, and is the length between opposing portions of the two conductive linear bodies 31 (see FIG. 2 ). When the conductive linear bodies 31 are arranged at uneven intervals, the interval L is the average value of the intervals between all adjacent conductive linear bodies 31.

The conductive linear body 31 may be produced by any method, such as etching, screen printing, or inkjet printing, but may be a linear body including a metal wire (hereinafter also referred to as a "metal wire linear body"). Metal wires have high thermal conductivity, high electrical conductivity, 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 heat generation of the laminate 100. This makes it possible to make the conductive linear body 31 less visible. That is, when a metal wire linear body is used as the conductive linear body 31, the resistance value of the wiring body 3 is reduced while the light transmittance is easily improved. In addition, the laminate 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 31 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 such as carbon black, activated carbon, hard carbon, soft carbon, mesoporous carbon, and carbon fiber; graphite, fullerene, graphene, and carbon nanotubes.

The conductive linear body 31 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. Other examples of the thread include threads made of metal fibers, carbon fibers, or ion-conductive polymer fibers. Examples of the conductive coating include coatings made 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 wiring body 3.

(First resin layer)
The first resin layer 4 directly or indirectly supports the wiring body 3. In addition, the first resin layer 4 can stabilize the resistance value of the wiring body 3. That is, the first resin layer 4 can fix the conductive linear body 31, stabilize the contact between the conductive linear body 31 and the electrode 5, and make it difficult for an increase in the resistance value to occur.
From the viewpoint of stabilizing the resistance value of the wiring body 3, the storage modulus of the first resin layer 4 at 23° C. is preferably 5.0×10 ⁶ Pa or more and 1.0×10 ¹⁰ Pa or less. From the same viewpoint, the storage modulus of the first resin layer 4 at 23° C. is more preferably 5.0×10 ⁷ Pa or more, and even more preferably 5.0×10 ⁸ Pa or more. The storage modulus of the first resin layer at 23° C. is more preferably 7.0×10 ⁹ Pa or less, and even more preferably 4.0×10 ⁹ Pa or less.
From the same viewpoint, the storage modulus of the first resin layer 4 at 105° C. is preferably 5.0×10 ⁷ Pa or more, and more preferably 5.0×10 ⁸ Pa or more. The storage modulus of the first resin layer 4 at 105° C. is preferably 7.0×10 ⁹ Pa or less, and more preferably 4.0×10 ⁹ Pa or less.
The storage modulus can be measured by the method described in the examples below.

The thickness of the first resin layer 4 is not particularly limited. The thickness of the first resin layer 4 may be equal to or greater than the diameter D of the conductive linear body 31, or may be less than the diameter D of the conductive linear body 31. If the thickness of the first resin layer 4 is equal to or greater than the diameter D of the conductive linear body 31, the wiring body 3 can be included in the first resin layer 4. If the thickness of the first resin layer 4 is less than the diameter D of the conductive linear body 31, the wiring body 3 is exposed from the first resin layer 4. In addition, when the wiring body 3 is exposed from the first resin layer 4, the wiring body 3 may be exposed on the side of the first substrate 1 or on the side of the second substrate 2. The thickness of the first resin layer 4 is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The thickness of the first resin layer 4 is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less.

From the viewpoint of setting the storage modulus within the above range, the first resin layer 4 is preferably a layer made of a cured product of a curable adhesive.
Examples of the curable adhesive include a thermosetting adhesive that is cured by heat, and an energy ray curable adhesive. Examples of the energy ray include ultraviolet rays, visible energy rays, infrared rays, and electron beams. Note that "energy ray curing" also includes heat curing by heating using energy rays.

The curable adhesive preferably contains a thermosetting resin. The thermosetting resin 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 compounds, and acid anhydride-based compounds. 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 compounds, and acid anhydride-based compounds, 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 compounds, and acid anhydride-based compounds, and it is preferable to use epoxy resin.

As epoxy resins, cyclic ones such as aromatic epoxy resins or alicyclic epoxy resins are preferred from the viewpoint of increasing the storage modulus of the first resin layer 4. Epoxy resins having flexible segments such as oxyalkylene chains tend to decrease the storage modulus of the first resin layer 4.

The energy ray curable adhesive preferably contains an energy ray curable resin. 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 preferred.

Examples of acrylate compounds include dicyclopentadiene diacrylate, 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. ) acrylate and other linear aliphatic skeleton-containing (meth)acrylates; cyclic aliphatic skeleton-containing (meth)acrylates such as dicyclopentanyl 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, polyether (meth)acrylates other than 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 more preferably 300 or more. The weight average molecular weight is preferably 30,000 or less, and more preferably 10,000 or less. The weight average molecular weight in this specification is a value calculated in terms of standard polystyrene measured by gel permeation chromatography (GPC).

The adhesive may contain one type of energy ray curable resin, or two or more types. When the adhesive contains two or more types of energy ray curable resin, the combination and ratio of the resins may be selected arbitrarily.

When using an energy ray curable resin or a thermosetting resin, it is preferable to use a photopolymerization initiator, a thermal polymerization initiator, or the like. By using a photopolymerization initiator, a thermal polymerization initiator, or the like, the polymerization reaction of the curable resin can be easily started, making it easier to control the curing reaction.

Photopolymerization initiators include photoradical polymerization initiators such as benzophenone, acetophenone, benzoin, benzoin methyl ether, 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.

In addition to photoradical polymerization initiators, photocationic polymerization initiators can also be used as photopolymerization initiators. Photocationic polymerization initiators are compounds that generate cationic species when irradiated with energy rays, initiating the curing reaction of cationic curable compounds, and consist of a cationic portion that absorbs energy rays and an anionic portion that serves as a source of acid generation.

Examples of photocationic polymerization initiators include sulfonium salt compounds, iodonium salt compounds, phosphonium salt compounds, ammonium salt compounds, antimony salt compounds, diazonium salt compounds, selenium salt compounds, oxonium salt compounds, and bromine salt compounds. Among these, sulfonium salt compounds are preferred from the viewpoints of excellent compatibility and excellent storage stability of the resulting adhesive, and aromatic sulfonium salt compounds having an aromatic group are more preferred.

Examples of sulfonium salt compounds include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, and triphenylsulfonium tetrakis(pentafluorophenyl)borate.

Iodonium salt compounds include diphenyliodonium tetrakis(pentafluorophenyl)borate, diphenyliodonium hexafluorophosphate, and (tricumyl)iodonium tetrakis(pentafluorophenyl)borate.

Phosphonium salt compounds include tri-n-butyl(2,5-dihydroxyphenyl)phosphonium bromide and hexadecyltributylphosphonium chloride.

Examples of ammonium salt compounds include benzyltrimethylammonium chloride, phenyltributylammonium chloride, and benzyltrimethylammonium bromide.

Examples of antimonate compounds include triphenylsulfonium hexafluoroantimonate, p-(phenylthio)phenyldiphenylsulfonium hexafluoroantimonate, and diaryliodonium hexafluoroantimonate.

Thermal polymerization initiators 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 thermal radical polymerization initiators such as benzoyl peroxide, lauroyl peroxide, peracetic acid, persuccinic acid, di-t-butyl peroxide, t-butyl hydroperoxide, and organic peroxides such as cumene hydroperoxide.

In addition to the above-mentioned thermal radical polymerization initiators, thermal cationic polymerization initiators can also be used as thermal polymerization initiators. Thermal cationic polymerization initiators are compounds that can generate cationic species that initiate polymerization when heated. Examples of thermal cationic polymerization initiators include sulfonium salts, quaternary ammonium salts, phosphonium salts, diazonium salts, and iodonium salts. Among these, sulfonium salts are preferred from the viewpoints of ease of availability and the ease with which products with superior adhesion and transparency can be obtained.

Sulfonium salts include triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, and triphenylsulfonium hexafluoroarsinate.

Examples of the quaternary ammonium salt include tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, and tetrabutylammonium hydrogen sulfate.
Examples of the phosphonium salt include ethyltriphenylphosphonium hexafluoroantimonate and tetrabutylphosphonium hexafluoroantimonate.

Diazonium salts include benzenediazonium chloride, etc. Iodonium salts include diphenyliodonium hexafluoroarsinate, bis(4-chlorophenyl)iodonium hexafluoroarsinate, and phenyl(4-methoxyphenyl)iodonium hexafluoroarsinate, etc.

These polymerization initiators may be used alone or in combination of two or more.
When these polymerization initiators are used to form a crosslinked structure, the amount used is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and particularly preferably 1 part by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the energy ray-curable resin or the thermosetting resin.

If a thermosetting resin is used, a curing catalyst such as an imidazole-based curing catalyst may be used.

In this embodiment, the curable adhesive may contain a flexibility adjusting component together with the energy ray curable resin or thermosetting resin to facilitate maintaining the sheet shape before curing. Examples of polymers used as flexibility adjusting components include phenoxy resin, polyolefin resin or modified products thereof, polyamideimide resin, polyimide resin, rubber resin, and acrylic resin.

These flexibility adjusting ingredients can be used alone or in combination of two or more.

When the curable adhesive used in this embodiment contains a flexibility adjusting component, the total amount of energy ray curable resin and thermosetting resin contained in the adhesive is, from the viewpoint of adjusting the storage modulus of the first resin layer 4 to the above-mentioned range, preferably 15 parts by mass or more and 300 parts by mass or less, more preferably 30 parts by mass or more and 250 parts by mass or less, and even more preferably 60 parts by mass or more and 200 parts by mass or less, per 100 parts by mass of the flexibility adjusting component. Furthermore, when the adhesive contains an energy ray curable resin or a thermosetting resin but does not contain a flexibility adjusting component, the storage modulus of the first resin layer 4 tends to be too high.

In the present embodiment, it is preferable that the curable adhesive does not contain a filler. When the adhesive does not contain a filler, it is possible to prevent the storage modulus at 23° C. of the first resin layer 4 from becoming too high.
However, the curable adhesive may contain a filler within a range in which the storage modulus at 23° C. of the first resin layer 4 can be adjusted to fall within the above range.

Fillers include, for example, inorganic powders such as silica, alumina, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, and boron nitride; beads made by shaping inorganic powders into spherical shapes, single crystal fibers, and glass fibers. Among these, silica filler and alumina filler are preferred. The fillers may be used alone or in combination of two or more types.

The curable adhesive may contain other components. Examples of other components include well-known additives such as organic solvents, coupling agents, flame retardants, tackifiers, UV absorbers, antioxidants, preservatives, fungicides, plasticizers, defoamers, and wettability adjusters.

(electrode)
The electrodes 5 are used to supply a current to the conductive linear body 31. The electrodes 5 are in a pair. The electrodes 5 are in direct contact with the conductive linear body 31. The electrodes 5 are disposed so as to be electrically connected to both ends of the conductive linear body 31.
The electrode 5 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 metals such as copper, aluminum, tungsten, iron, molybdenum, nickel, titanium, silver, and gold, or alloys containing two or more metals such as stainless steel, carbon steel, brass, phosphor bronze, zirconium copper alloy, beryllium copper, iron nickel, nichrome, nickel titanium, Kanthal, Hastelloy, and rhenium tungsten. The metal foil or metal wire may also be plated with gold, tin, zinc, silver, nickel, chromium, nickel chromium alloy, or solder.

The width of at least one of the electrodes 5 is preferably 10 mm or less, and more preferably 3 mm or less, in a plan view of the laminate 100. The width of this electrode is preferably 0.1 mm or more, and more preferably 0.5 mm or more. If at least one of the electrodes is a metal wire, the width of the electrode is the diameter of the metal wire, and if 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 5 is preferably 2 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The thickness of the electrode 5 is preferably 200 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and particularly preferably 25 μm or less. If the thickness of the electrode 5 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.

(Second Resin Layer)
The second resin layer 6 is provided between the first substrate 1 or the second substrate 2, and the wiring sheet 10. The second resin layer 6 has a lower storage modulus than the first resin layer 4. This second resin layer 6 can prevent cracks from occurring in the second substrate 2. In this embodiment, the second substrate 2 and the wiring sheet 10 are laminated with the second resin layer 6 interposed therebetween.
From the viewpoint of preventing cracks, the storage modulus of the second resin layer 6 at 23° C. is preferably 1.0×10 ⁴ Pa or more and 3.0×10 ⁵ Pa or less. From the same viewpoint, the storage modulus of the second resin layer 6 at 23° C. is more preferably 4.0×10 ⁴ Pa or more, and even more preferably 8.0×10 ⁴ Pa or more. The storage modulus of the second resin layer 6 at 23° C. is more preferably 2.5×10 ⁵ Pa or less, and even more preferably 2.0×10 ⁵ Pa or less.
From the same viewpoint, the storage modulus of the second resin layer 6 at 105° C. is preferably 5.0×10 ³ Pa or more, and more preferably 1.0×10 ⁴ Pa or more. The storage modulus of the second resin layer 6 at 105° C. is preferably 4.0×10 ⁴ Pa or less, and more preferably 3.0×10 ⁴ Pa or less.
The storage modulus can be measured by the method described in the examples below.

The thickness of the second resin layer 6 is not particularly limited. The thickness of the second resin layer 6 is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The thickness of the second resin layer 6 is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 300 μm or less.

The second resin layer 6 is preferably an adhesive layer as described below, from the viewpoint of excellent performance as an adhesive layer and of having a storage modulus within the above range.

The adhesive layer can be composed of an adhesive obtained by crosslinking (thermal crosslinking) an adhesive composition (hereinafter sometimes referred to as "adhesive composition P") containing, for example, a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B), or an energy ray curable component (C), or both. Note that, if desired, this adhesive composition P preferably further contains a photopolymerization initiator (D). In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the concept of "copolymer" is also included in "polymer."

When the adhesive composition P contains the energy ray curable component (C), the adhesive layer obtained by crosslinking the adhesive composition P has not yet been cured by energy rays at the stage of the adhesive sheet, i.e., before being attached to the adherend, and has a relatively low storage modulus. Therefore, it is possible to alleviate the stress that occurs when the adhesive layer is attached to the adherend. As a result, even when the adhesive layer is attached to the surface of the adherend that has irregularities, the adhesive layer easily follows the irregularities, and the occurrence of gaps, floating, etc. near the irregularities is suppressed, and excellent adhesion to the adherend is demonstrated.

The (meth)acrylic acid ester polymer (A) preferably contains, as monomer units constituting this polymer, an alkyl (meth)acrylic acid ester and a monomer having a reactive functional group in the molecule (a reactive functional group-containing monomer).

The (meth)acrylic acid ester polymer (A) can exhibit favorable adhesion by containing an alkyl (meth)acrylic acid ester as a monomer unit constituting this polymer. As the alkyl (meth)acrylic acid ester, an alkyl (meth)acrylic acid ester having 1 to 20 carbon atoms is preferable. The alkyl group may be linear or branched, or may have a cyclic structure.

Examples of (meth)acrylic acid alkyl esters having an alkyl group with 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate. These may be used alone or in combination of two or more.

Among these, the (meth)acrylic acid alkyl esters are preferably those having an alkyl group with 4 to 20 carbon atoms. As the (meth)acrylic acid alkyl esters having an alkyl group with 4 to 20 carbon atoms, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isobornyl (meth)acrylate, etc. are preferred, and from the viewpoint of obtaining excellent adhesion, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, etc. are more preferred, and n-butyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, etc. are particularly preferred.

The (meth)acrylic acid ester polymer (A) preferably contains 40% by mass or more of (meth)acrylic acid alkyl ester as a monomer unit constituting this polymer, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more. When the (meth)acrylic acid alkyl ester is contained at 40% by mass or more, the (meth)acrylic acid ester polymer (A) can exhibit suitable adhesion. In addition, the (meth)acrylic acid ester polymer (A) preferably contains 99% by mass or less of (meth)acrylic acid alkyl ester as a monomer unit constituting this polymer, particularly preferably 95% by mass or less, and even more preferably 90% by mass or less. By making the (meth)acrylic acid alkyl ester 99% by mass or less, other monomer components can be introduced into the (meth)acrylic acid ester polymer (A) in suitable amounts. In particular, when the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a monomer constituting this polymer, the (meth)acrylic acid ester polymer (A) preferably contains 87% by mass or less, and more preferably 83% by mass or less, of (meth)acrylic acid alkyl ester as a monomer unit constituting this polymer.

The (meth)acrylic acid ester polymer (A) contains a reactive functional group-containing monomer as a monomer unit constituting this polymer, and reacts with the crosslinking agent (B) described below via the reactive functional group derived from the reactive functional group-containing monomer, forming a crosslinked structure (three-dimensional network structure) and resulting in an adhesive with the desired cohesive strength.

Preferred examples of reactive functional group-containing monomers contained in the (meth)acrylic acid ester polymer (A) as monomer units constituting this polymer include monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomers), monomers having a carboxyl group in the molecule (carboxyl group-containing monomers), and monomers having an amino group in the molecule (amino group-containing monomers). These reactive functional group-containing monomers may be used alone or in combination of two or more.

Among the reactive functional group-containing monomers, hydroxyl group-containing monomers or carboxyl group-containing monomers are preferred from the viewpoint of ease of adjusting the crosslink density and of obtaining an adhesive with the desired cohesive strength, and hydroxyl group-containing monomers are preferred from the viewpoint of adhesive strength and resistance to wet heat whitening.

Hydroxyl group-containing monomers include, for example, hydroxyalkyl (meth)acrylate esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, hydroxyalkyl (meth)acrylate esters having a hydroxyalkyl group with 1 to 4 carbon atoms are preferred. Specifically, for example, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and in particular, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferred. These may be used alone or in combination of two or more.

Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferred from the viewpoint of the cohesive strength of the resulting (meth)acrylic acid ester polymer (A). These may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (A) preferably contains 1% by mass or more of reactive functional group-containing monomer as a monomer unit constituting this polymer, more preferably 3% by mass or more, and even more preferably 5% by mass or more. When the reactive functional group-containing monomer is a hydroxyl group-containing monomer, it is preferably contained 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. When the reactive functional group-containing monomer is a hydroxyl group-containing monomer, it is preferably contained less than 25% by mass, more preferably 20% by mass or less, and even more preferably 16% by mass or less. When the (meth)acrylic acid ester polymer (A) is a monomer unit constituting this polymer, it is preferably contained 50% by mass or less of reactive functional group-containing monomer as a monomer unit constituting this polymer, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

It is also preferable that the (meth)acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting this polymer. By having the nitrogen atom-containing monomer exist as a constituent unit in the polymer, a predetermined polarity is imparted to the adhesive, and it is possible to make it have excellent affinity even for adherends having a certain degree of polarity, such as glass. In addition to the amino group-containing monomers as the reactive functional group-containing monomers described above, examples of the nitrogen atom-containing monomer include monomers having amide groups and monomers having nitrogen-containing heterocycles. Among these, from the viewpoint of imparting appropriate rigidity to the (meth)acrylic acid ester polymer (A), monomers having nitrogen-containing heterocycles are preferred.

In addition, examples of the nitrogen atom-containing monomer that can be used include N-vinyl carboxylic acid amide, (meth)acrylamide, N-methyl(meth)acrylamide, N-methylol(meth)acrylamide, N-tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-ethyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-phenyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, and N-vinyl caprolactam.
These nitrogen atom-containing monomers may be used alone or in combination of two or more.

　Examples of monomers having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinylphthalimide. Among these, N-(meth)acryloylmorpholine is preferred because it exhibits superior adhesive strength, and N-acryloylmorpholine (4-acryloylmorpholine) is particularly preferred.

When the (meth)acrylic acid ester polymer (A) contains a monomer having a nitrogen-containing heterocycle as a monomer unit constituting this polymer, it preferably contains 0.5 mass% or more of the nitrogen atom-containing monomer, more preferably 1 mass% or more, and even more preferably 3 mass% or more. Furthermore, the (meth)acrylic acid ester polymer (A) preferably contains 20 mass% or less of the monomer having a nitrogen-containing heterocycle as a monomer unit constituting this polymer, more preferably 15 mass% or less, and even more preferably 8 mass% or less. When the content of the monomer having a nitrogen-containing heterocycle is within the above range, the resulting adhesive can effectively exhibit excellent adhesion to adherends such as glass.

The (meth)acrylic acid ester polymer (A) may contain other monomers as monomer units constituting this polymer, if desired. Examples of other monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (A) is preferably a linear polymer. By using a linear polymer, entanglement of molecular chains occurs more easily, and it is expected that the cohesive strength will be improved, resulting in a superior adhesive.

The polymerization form of the (meth)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 200,000 or more, more preferably 300,000 or more, and even more preferably 400,000 or more. If the lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is above the above limit, the second resin layer and the laminate will have excellent long-term durability.

The weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 2 million or less, more preferably 1.5 million or less, even more preferably 1 million or less, and particularly preferably 800,000 or less. When the upper limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is the above or less, the resulting pressure-sensitive adhesive has at least one of better adhesion and better sticking ability to the adherend.

In addition, in the adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more kinds.

The crosslinking agent (B) crosslinks the (meth)acrylic acid ester polymer (A) by heating the adhesive composition P, making it possible to form a good three-dimensional mesh structure. This results in an adhesive with improved cohesive strength.

The crosslinking agent (B) may be any that reacts with the reactive functional group of the (meth)acrylic acid ester polymer (A), and examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. Among these, when the reactive functional group of the (meth)acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent that has excellent reactivity with the hydroxyl group, and when the reactive functional group of the (meth)acrylic acid ester polymer (A) is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent that has excellent reactivity with the carboxyl group. The crosslinking agent (B) may be used alone or in combination of two or more types.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and biuret and isocyanurate forms thereof, as well as adducts which are reaction products with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates are preferred from the viewpoint of reactivity with hydroxyl groups, and it is particularly preferred to use at least one of trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate.

Epoxy crosslinking agents include 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, and diglycidylamine. Among these, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane is preferred from the viewpoint of reactivity with carboxy groups.

The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of the (meth)acrylic acid ester polymer (A). This content is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less. By having the content of the crosslinking agent (B) within the above range, the degree of crosslinking becomes appropriate, and the obtained adhesive becomes superior because it becomes easier to adjust the storage modulus described above to a suitable value.

Since the adhesive composition P contains the energy ray curable component (C), the adhesive obtained by crosslinking (thermal crosslinking) the adhesive composition P becomes an energy ray curable adhesive. It is presumed that this adhesive is cured by irradiation with energy rays after attachment to an adherend, whereby the energy ray curable components (C) polymerize with each other, and the polymerized energy ray curable components (C) become entangled in the crosslinked structure (three-dimensional network structure) of the (meth)acrylic acid ester polymer (A). An adhesive with such a high-order structure has high cohesive strength and exhibits high coating strength.

The energy ray-curable component (C) is not particularly limited as long as it is a component that cures when irradiated with energy rays and provides the above-mentioned effects, and may be any of a monomer, oligomer, or polymer, or a mixture thereof. Among these, preferred examples include polyfunctional acrylate monomers that have excellent compatibility with the (meth)acrylic acid ester polymer (A) and the like.

Multifunctional acrylate monomers include tricyclodecane dimethanol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethoxylated bisphenol A diacrylate, and 2-amino acids such as 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene. functional types; trifunctional types such as trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, and ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate; tetrafunctional types such as diglycerin tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate; pentafunctional types such as propionic acid-modified dipentaerythritol penta(meth)acrylate; and hexafunctional types such as dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate. Among the above, it is preferable to use at least one of ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate and tricyclodecane dimethanol di(meth)acrylate. These may be used alone or in combination of two or more. In addition, from the viewpoint of compatibility with the (meth)acrylic acid ester polymer (A), it is preferable that the polyfunctional acrylate monomer has a molecular weight of less than 1000.

The content of the energy ray curable component (C) in the adhesive composition P is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A), from the viewpoint of making it easier to adjust the storage modulus of the resulting adhesive to the desired value. On the other hand, this content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 7.5 parts by mass or less, from the viewpoint of preventing phase separation of the energy ray curable component (C) from the (meth)acrylic acid ester polymer (A) and from the viewpoint of making it easier to adjust the storage modulus to the desired value.

When ultraviolet light is used as the energy ray to cure the energy ray-curable adhesive, it is preferable that the adhesive composition P further contains a photopolymerization initiator (D). By containing the photopolymerization initiator (D) in this way, the energy ray-curable component (C) can be polymerized efficiently, and the polymerization curing time and the amount of energy ray irradiation can be reduced.

Examples of the photopolymerization initiator (D) 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, benzyl, dibenzyl, diacetyl, β-chloroanthraquinone, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone, 2-benzothiazole-N,N-diethyldithiocarbamate, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. These may be used alone or in combination of two or more.

The content of the photopolymerization initiator (D) in the adhesive composition P is preferably 0.1 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 5.0 parts by mass or more, relative to 100 parts by mass of the energy ray-curable component (C). This content is preferably 35 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 15 parts by mass or less. When the content of the photopolymerization initiator (D) is within this range, it is cleaved without problems upon irradiation with energy rays, and the curability of the energy ray-curable component (C) is further improved. In addition, the storage modulus described above is more likely to be satisfied.

If desired, various additives that are commonly used in acrylic adhesives can be used in the adhesive composition P. Examples of various additives include silane coupling agents, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, fillers, and refractive index adjusters.

(Method for manufacturing laminate)
There is no particular limitation on the method for producing the laminate 100 according to this embodiment. The laminate 100 can be produced, for example, by the following steps.
First, a process for producing a wiring film including the wiring body 3 is performed. In this process, a thermosetting adhesive for forming the first resin layer 4 is applied onto a release film to form a coating film. Next, the coating film is dried to produce an adhesive layer. Next, the conductive linear bodies 31 are arranged on the adhesive layer to form the wiring body 3. For example, in a state where an adhesive layer with a release film is arranged on the outer circumferential surface of a drum member, the conductive linear bodies 31 are wound spirally on the adhesive layer while rotating the drum member. Then, the bundle of conductive linear bodies 31 wound spirally is cut along the axial direction of the drum member. This forms the wiring body 3 and places it on the adhesive layer. In this way, a wiring film in which the wiring body 3 is formed on the adhesive layer with a release film is obtained. According to this method, for example, by moving the unwinding portion of the conductive linear bodies 31 along a direction parallel to the axis of the drum member while rotating the drum member, it is easy to adjust the interval L between adjacent conductive linear bodies 31 in the wiring body 3.
Next, a step of providing a pair of electrodes 5 on the first substrate 1 is performed. In this step, for example, a conductive paste or the like is printed in a predetermined arrangement on the first substrate 1, and then dried, so that the pair of electrodes 5 can be provided.
Next, a process is performed in which a wiring film is placed on the first substrate 1 provided with the pair of electrodes 5, and the thermosetting adhesive is cured. In this process, the wiring film is bonded onto the first substrate 1 provided with the pair of electrodes 5 so that the pair of electrodes 5 contact both ends of the conductive linear members 31 in the wiring 3 of the wiring film. Then, after removing the release film, a predetermined heat treatment is performed on the thermosetting adhesive to form a first resin layer 4, and a wiring sheet 10 is formed on the first substrate 1.

Meanwhile, a process is performed to prepare a protective film including a second substrate 2 and a second resin layer 6. In this process, a pressure-sensitive adhesive composition P for forming the second resin layer 6 is applied onto the second substrate 2 to form a coating film, thereby preparing the protective film. As shown in Figs. 1 and 2, it is preferable to provide two holes in the second substrate 2.
Next, a step is performed in which a protective film is placed on the first substrate 1 on which the wiring sheet 10 is provided, and the adhesive composition P is crosslinked. In this step, the protective film is attached to the first substrate 1 on which the wiring sheet 10 is provided, so that, in a plan view, two holes in the protective film overlap the pair of electrodes 5, and the coating of the adhesive composition P on the protective film contacts the wiring sheet 10. Then, a predetermined energy ray is irradiated to the coating of the adhesive composition P, thereby forming a second resin layer 6, and the laminate 100 is produced.

(Functions and Effects of the First Embodiment)
According to this embodiment, the following advantageous effects can be obtained.
(1) According to this embodiment, the second resin layer 6 is easily deformed due to its low storage modulus. Therefore, when the laminate 100 becomes hot, the second resin layer 6 deforms, thereby relaxing the distortion generated in the second base material 2. In this way, the generation of cracks in the second base material 2 can be prevented.
(2) According to the present embodiment, the storage modulus of the second resin layer 6 at 23° C. is set to 1.0×10 ⁴ Pa or more and 3.0×10 ⁵ Pa or less, so that the second resin layer 6 is easily deformed and distortion generated in the second base material 2 can be alleviated.
(3) According to this embodiment, the first resin layer 4 can fix the conductive linear body 31, suppress deformation in the thickness direction inside the laminate 100, stabilize the contact between the conductive linear body 31 and the electrode 5, and stabilize the resistance value of the wiring body 3.
(4) According to the present embodiment, the storage modulus of the first resin layer 4 at 23° C. is set to be 5.0×10 ⁶ Pa or more and 1.0×10 ¹⁰ Pa or less. As a result, when the laminate 100 is deformed, the conductive linear body 31 can be fixed while preventing the connection portion between the conductive linear body 31 and the electrode 5 from being destroyed.
(5) The laminate 100 according to this embodiment can be produced in a relatively simple manner using the above-described laminate production method.

[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the contents of this embodiment. In the drawings, some parts are illustrated enlarged or reduced in size for ease of explanation.
The second embodiment differs from the first embodiment in that, in a cross-sectional view of the laminate 100A, a first substrate 1 and a wiring sheet 10 are laminated via a second resin layer 6.
In the following description, differences from the first embodiment will be mainly described, and overlapping descriptions will be omitted or simplified. The same components as those in the first embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted or simplified.

As shown in FIG. 3, the laminate 100A according to this embodiment includes a first substrate 1, a second substrate 2 having a higher linear expansion coefficient than the first substrate 1, and a wiring sheet 10 sandwiched between the first substrate 1 and the second substrate 2. The wiring sheet 10 includes a wiring body 3 in which a plurality of conductive linear bodies 31 are arranged at intervals, a first resin layer 4 that directly or indirectly supports the wiring body 3, and a pair of electrodes 5 that directly contact the conductive linear bodies 31. The first substrate 1 and the wiring sheet 10 are laminated via a second resin layer 6 having a lower storage modulus than the first resin layer 4.

(Functions and Effects of the Second Embodiment)
According to this embodiment, it is possible to achieve the effects (1) to (4) of the first embodiment.

[Modifications of the embodiment]
The present invention is not limited to the above-described embodiment, and any modifications or improvements that can achieve the object of the present invention are included in the present invention.
For example, in the above embodiment, the laminate 100 includes the film-like first substrate 1, but is not limited thereto. For example, the first substrate 1 may be a substrate formed into a three-dimensional shape. In such a case, the wiring sheet 10 can be used by being attached to the first substrate 1, which is an adherend, by the first resin layer 4 or the second resin layer 6.
In the second embodiment described above, the first substrate 1 and the wiring sheet 10 are laminated via the second resin layer 6 in the cross-sectional view of the laminate 100A, but the modified examples are not limited thereto. For example, there are two other modified examples. One modified example is an example in which the wiring sheet 10 is turned upside down (the electrode 5 is provided on the second substrate 2 side) from the first embodiment. The other modified example is an example in which the wiring sheet 10 is turned upside down (the electrode 5 is provided on the second substrate 2) from the second embodiment.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.
The laminates obtained in the examples were evaluated as follows.

[Crack evaluation]
After the laminate was allowed to stand at 105° C. for 1000 hours, the presence or absence of cracks in the base layer of the laminate was confirmed using a digital microscope.

[Storage modulus measurement]
A cylindrical test sample with a diameter of 8 mm and a thickness of 1 mm was prepared from the same composition as the composition forming the layer to be measured. The storage modulus of the test sample was measured using a viscoelasticity measuring device (manufactured by Anton Paar, device name "MCR300") under the conditions of a test start temperature of -20°C, a test end temperature of 150°C, a heating rate of 3°C/min, a shear strain of 0.05%, and a frequency of 1 Hz, using a parallel plate with a diameter of 8 mm as a measuring jig.

[Measurement of linear expansion coefficient]
The substrate was cut into a rectangle of 4.5 mm x 20 mm to prepare a test sample. The linear expansion coefficient of the test sample was measured using a thermomechanical analyzer (manufactured by Netzsch Japan, product name "TMA4000SE") under the conditions of a tensile load of 2 g, a temperature range of 23 to 105°C, and a heating rate of 5°C/min.

[Preparation Example 1]
A curable adhesive was obtained by blending 100 parts by mass of a phenoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "YX7200B35") with 170 parts by mass of a polyfunctional hydrogenated bisphenol A diglycidyl ether epoxy compound (manufactured by Mitsubishi Chemical Corporation, product name "YX8000"), 0.2 parts by mass of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-4803"), 2 parts by mass of a thermal cationic polymerization initiator (manufactured by Sanshin Chemical Industry Co., Ltd., product name "SAN-AID SI-B3"), and 2 parts by mass of a thermal cationic polymerization initiator (manufactured by Sanshin Chemical Industry Co., Ltd., product name "SAN-AID SI-B7")

[Preparation Example 2]
(Preparation of (meth)acrylic acid ester polymer (A))
65 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of 4-acryloylmorpholine, 15 parts by mass of isobornyl acrylate, and 15 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth)acrylic acid ester polymer (A). The molecular weight of this (meth)acrylic acid ester polymer (A) was measured, and the weight average molecular weight (Mw) was 500,000. The glass transition temperature (Tg, unit: ° C.) of this (meth)acrylic acid ester polymer (A) was calculated by the FOX formula based on the glass transition temperatures (Tg) of the respective monomers constituting the (meth)acrylic acid ester polymer (A) as homopolymers, and was found to be −36.5° C.
(Preparation of adhesive composition)
100 parts by mass of the obtained (meth)acrylic acid ester polymer (A) (solid content equivalent, the same applies below), 0.18 parts by mass of trimethylolpropane-modified tolylene diisocyanate as a crosslinking agent (B), 7 parts by mass of ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate as an energy ray-curable component (C), 0.7 parts by mass of a mixture of benzophenone and 1-hydroxycyclohexyl phenyl ketone in a 1:1 mass ratio as a photopolymerization initiator (D), and 0.28 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of a pressure-sensitive adhesive composition.

[Preparation Example 3]
(Preparation of adhesive composition)
100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in Preparation Example 2, 0.15 parts by mass of trimethylolpropane-modified tolylene diisocyanate as the crosslinking agent (B), 5 parts by mass of ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate as the energy ray curable component (C), 0.5 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as the photopolymerization initiator (D), and 0.25 parts by mass of 3-glycidoxypropyltrimethoxysilane as the silane coupling agent were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of an adhesive composition.

[Preparation Example 4]
(Preparation of (meth)acrylic acid ester polymer (A))
A (meth)acrylic acid ester polymer (A) was prepared by copolymerizing 30 parts by mass of 2-ethylhexyl acrylate, 25 parts by mass of n-butyl acrylate, 5 parts by mass of 4-acryloylmorpholine, 15 parts by mass of isobornyl acrylate, and 25 parts by mass of 2-hydroxyethyl acrylate. The molecular weight of this (meth)acrylic acid ester polymer (A) was measured, and the weight average molecular weight (Mw) was 600,000.
(Preparation of adhesive composition)
100 parts by mass of the obtained (meth)acrylic acid ester polymer (A), 0.2 parts by mass of trimethylolpropane-modified tolylene diisocyanate as a crosslinking agent (B), 8.0 parts by mass of ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate as an energy ray curable component (C), 0.8 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as a photopolymerization initiator (D), and 0.2 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of a pressure-sensitive adhesive composition.

[Example 1]
(Preparation of Wiring Film)
The curable adhesive obtained in Preparation Example 1 was applied to a 38 μm-thick release film (manufactured by Lintec Corporation, product name "SP-382150") to a thickness of 15 μm, and cut into a rectangle of 250 mm x 320 mm to prepare an adhesive sheet. A gold-plated tungsten wire (diameter 10 μm, hereinafter also referred to as wire) was prepared as a conductive linear body. Next, the obtained adhesive sheet was wound around a drum member with a rubber outer circumferential surface, with the surface of the pressure-sensitive adhesive layer facing outward and without wrinkles, and both ends of the adhesive sheet in the circumferential direction were fixed with double-sided tape. The wire wound around the bobbin was attached to the surface of the pressure-sensitive adhesive layer of the adhesive sheet located near the end of the drum member, and the wire was wound around the drum member while being unwound, and the drum member was gradually moved in a direction parallel to the drum axis so that the wire was wound around the drum member while drawing a spiral at equal intervals of 3 mm. As a result, a wiring body was formed with 96 wires lined up on the surface of the adhesive. Thereafter, the wires were cut, and the wiring body was removed from the drum member. The wiring body was cut to a width of 40×82 mm so that 12 wires could be taken out, and a wiring body film was produced.

(Preparation of Substrate with Electrodes)
Silver paste was screen-printed onto a 2 mm-thick glass substrate (linear expansion coefficient 3.3×10 ^-6 /° C.) as a first substrate so that the width was 2 mm and the distance between the electrodes was 7.8 mm, and then dried at a temperature of 150° C. for 30 minutes to form strip electrodes having a thickness of 17 μm. The strip electrodes were then subjected to electroless plating to produce a substrate with electrodes.

(Formation of wiring sheet)
The obtained wiring film was attached to the obtained electrode-attached substrate so that the electrodes were located at both ends of the wires. Then, the substrate was heated at a temperature of 120° C. and a pressure of 0.5 MPa for 30 minutes to harden the adhesive and form a first resin layer, thereby forming a wiring sheet on the first base material.
The storage elastic modulus of the first resin layer at 23°C was 2.2×10 ⁹ Pa, and the storage elastic modulus of the first resin layer at 105°C was 1.6×10 ⁹ Pa.

(Preparation of protective sheet)
The adhesive composition coating solution obtained in Preparation Example 2 was coated to a thickness of 100 μm on a cycloolefin polymer film (manufactured by Zeon Corporation, product name "ZF16") as a second substrate, and cut into a rectangle of 50 mm × 120 mm. Then, a circle with a diameter of 5 mm was cut out so that the center-to-center distance between the two circles was 7.8 mm, forming two holes to prepare a protective sheet.
The linear expansion coefficient of the second substrate is shown in Table 1.

(Preparation of Laminate)
The protective sheet was attached to the first substrate provided with the wiring sheet so that the electrodes of the wiring sheet and the circles of the protective sheet were aligned. Thereafter, ultraviolet light having a wavelength of 365 nm was irradiated under conditions of an illuminance of 200 mW/cm ² and a light quantity of 1000 mJ/cm ² to form a second resin layer, thereby obtaining a laminate.
The laminate thus obtained was evaluated for cracks. Table 1 also shows the storage modulus of the second resin layer at 23° C. and 105° C.

[Example 2]
A laminate was produced in the same manner as in Example 1, except that the cycloolefin polymer film (manufactured by Nippon Zeon Co., Ltd., product name "ZF16") of the protective sheet was changed to a polycarbonate film (manufactured by Teijin Limited, product name "L-100").

[Example 3]
A laminate was prepared in the same manner as in Example 1, except that the coating solution of the adhesive composition obtained in Preparation Example 2 of the protective sheet was changed to the coating solution of the adhesive composition obtained in Preparation Example 3.

[Comparative Example 1]
A laminate was prepared in the same manner as in Example 1, except that the coating solution of the adhesive composition obtained in Preparation Example 2 of the protective sheet was changed to the coating solution of the adhesive composition obtained in Preparation Example 4.

[Comparative Example 2]
A laminate was produced in the same manner as in Example 1, except that the coating solution of the adhesive composition obtained in Preparation Example 2 of the protective sheet was changed to the coating solution of the adhesive composition obtained in Preparation Example 4, and the cycloolefin polymer film (manufactured by Zeon Corporation, product name "ZF16") was changed to a polycarbonate film (manufactured by Teijin Limited, product name "L-100").

As shown in Table 1, the laminates obtained in Examples 1 to 3 had good crack evaluation results. This confirmed that the present invention can provide a laminate that can prevent cracks from occurring in the substrate.

1...first substrate, 2...second substrate, 3...wiring body, 31...conductive linear body, 4...first resin layer, 5...electrode, 6...second resin layer, 10...wiring sheet, 100, 100A...laminate.

Claims

A laminate including a first substrate, a second substrate having a linear expansion coefficient higher than that of the first substrate, and a wiring sheet sandwiched between the first substrate and the second substrate,
the wiring sheet includes a wiring body in which a plurality of conductive linear bodies are arranged at intervals, a first resin layer that directly or indirectly supports the wiring body, and a pair of electrodes that directly contact the conductive linear bodies,
The first substrate or the second substrate and the wiring sheet are laminated via a second resin layer having a storage modulus lower than that of the first resin layer.
Laminate.
The laminate according to claim 1 ,
The second resin layer has a storage modulus at 23° C. of 1.0×10 4 Pa or more and 3.0×10 5 Pa or less.
Laminate.
The laminate according to claim 1 or 2,
The storage modulus of the first resin layer at 23° C. is 5.0×10 6 Pa or more and 1.0×10 10 Pa or less.
Laminate.
The laminate according to claim 1 or 2,
The linear expansion coefficient of the first substrate is 0.01×10 −6 /° C. or more and 10×10 −6 /° C. or less.
Laminate.
The laminate according to claim 1 or 2,
The linear expansion coefficient of the second base material is 50×10 −6 /° C. or more and 100×10 −6 /° C. or less.
Laminate.
The laminate according to claim 1 or 2,
The second base material and the wiring sheet are laminated via the second resin layer.
Laminate.