Conductive film, and touch panel

Abstract

To provide a conductive film which is excellent in sulfurization resistance of a sensor electrode, and is excellent in conductivity after thermally compression bonding to a flexible printed wiring board in an external connection terminal, and a touch panel having the conductive film.SOLUTION: A conductive film has a base material, a sensor electrode which is disposed on at least one surface side of the base material, and is composed of a thin metal wire, a lead-out wiring which is electrically connected to the sensor electrode, a conductive pattern including an external connection terminal electrically connected to the lead-out wiring, and a protective layer covering the whole surface of the conductive pattern, wherein the protective layer contains a resin having a repeating unit A derived from monofunctional (meth) acrylate having a cyclic structure, and a repeating unit B derived from polyfunctional (meth) acrylate, a glass transition temperature of the protective layer is 50 to 130°C, thickness of the protective layer from the protective layer surface to the sensor electrode surface is 0.5 μm or more, and thickness of the protective layer from the protective layer surface to the external connection terminal surface is 3.0 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a conductive film and a touch panel. [Background technology]

[0002] Conductive films with conductive thin wires (thin wire-like wiring that exhibits conductivity) are widely used in a variety of applications, such as touch panels, solar cells, and EL (electroluminescence) elements. In particular, in recent years, the rate at which touch panels are installed in mobile phones and portable game devices has increased, and the demand for conductive films for capacitive touch panels that are capable of multi-point detection has rapidly expanded.

[0003] For example, Patent Document 1 discloses a technology relating to a display member having a photocurable resin composition containing a polymer (A), a radically polymerizable monomer (B), and a cationically polymerizable monomer (C) in predetermined amounts, and a functional layer formed by curing the photocurable resin composition, with the functional layer being located on one side of a resin film, and it is also described that the display member can be used as a touch panel member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-119086 Summary of the Invention [Problem to be solved by the invention]

[0005] Such touch panels are equipped with various peripheral components in addition to the conductive film. The cushioning materials and adhesives used in these peripheral components may contain sulfur-containing compounds. Furthermore, sulfur components such as H2S and SO2 are present in the environment in which the touch panel is used. Therefore, for conductive films with sensor electrodes made of thin metal wires, further improvement in the sulfuration resistance of the sensor electrodes is required. Furthermore, there is a demand for conductive films that provide improved electrical conductivity between external connection terminals and flexible printed circuit boards (FPCs) when thermocompression bonded to the FPCs.

[0006] The inventors have studied the performance of conductive films with reference to the technology disclosed in Patent Document 1, and have found that a conductive film having a protective layer formed using a polyfunctional monomer having a cyclic structure as described in Patent Document 1 may not be able to achieve both the two goals of improving the sulfurization resistance of the sensor electrode and ensuring conductivity after thermocompression bonding to an FPC at the external connection terminal, and that there is room for improvement.

[0007] In view of the above circumstances, an object of the present invention is to provide a conductive film that has excellent sulfur resistance for a sensor electrode and excellent conductivity after thermocompression bonding to a flexible printed wiring board at an external connection terminal, and to provide a touch panel having the conductive film. [Means for solving the problem]

[0008] As a result of extensive research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by the following configuration.

[0009] [1] A conductive film having a substrate, a conductive pattern including a sensor electrode composed of thin metal wires arranged on at least one surface side of the substrate, a lead wiring electrically connected to the sensor electrode, and an external connection terminal electrically connected to the lead wiring, and a protective layer covering the entire surface of the conductive pattern, wherein the protective layer contains a resin having a repeating unit A derived from a monofunctional (meth)acrylate having a cyclic structure and a repeating unit B derived from a polyfunctional (meth)acrylate, the glass transition temperature of the protective layer is 50 to 130°C, the thickness of the protective layer from the surface of the protective layer to the surface of the sensor electrode is 0.5 μm or more, and the thickness of the protective layer from the surface of the protective layer to the surface of the external connection terminal is 3.0 μm or less. [2] The conductive film according to [1], wherein the polyfunctional (meth)acrylate is a bifunctional (meth)acrylate. [3] The conductive film according to [2], wherein, in a linking structure linking two (meth)acryloyl groups possessed by the bifunctional (meth)acrylate, when a path is imagined that starts from an oxygen atom linked to one of the two (meth)acryloyl groups and ends at an oxygen atom linked to the other of the two (meth)acryloyl groups, and traces the atoms and interatomic bonds contained in the linking structure so as to minimize the number of atoms, the number Nb of atoms contained in the path including the oxygen atom at the starting point and the oxygen atom at the end point is 5 to 11. [4] The conductive film according to any one of [1] to [3], wherein the monofunctional (meth)acrylate has 9 to 17 carbon atoms. [5] The conductive film according to any one of [1] to [4], wherein the cyclic structure is a monocyclic structure or a structure in which monocyclic structures are linked by a single bond. [6] The conductive film according to any one of [1] to [5], wherein the monofunctional (meth)acrylate includes at least one selected from the group consisting of cyclohexyl acrylate and 2-(2-biphenylyloxy)ethyl acrylate. [7] A touch panel having the conductive film according to any one of [1] to [6]. [Effects of the Invention]

[0010] According to the present invention, a conductive film can be provided that has excellent sulfur resistance for a sensor electrode and excellent conductivity after thermocompression bonding to a flexible printed wiring board at an external connection terminal, and a touch panel having the conductive film can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing an example of the configuration of a conductive film of the present invention. [Figure 2] 1 is a plan view showing an example of the configuration of a conductive pattern included in a conductive film of the present invention. [Figure 3] FIG. 2 is a plan view showing an example of a mesh pattern of a sensor electrode of the conductive film of the present invention. [Figure 4] 10 is a plan view showing an example of the configuration of a sensor electrode and lead wiring included in a conductive pattern. FIG. [Figure 5] 10 is a plan view showing an example of the configuration of an external connection terminal of a conductive pattern. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the conductive film and touch panel of the present invention will be described in detail with reference to the drawings. The following description of the components is based on a representative embodiment of the present invention, and the present invention is not limited to such an embodiment. The drawings shown below are examples for explaining the present invention, and are not intended to limit the present invention. In the drawings shown below, the scale of each component may be changed from the actual scale for ease of visualization or explanation.

[0013] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, when two or more types of a component are present, the "content" of that component means the total content of those two or more components. In this specification, "g" and "mg" represent "g mass" and "mg mass", respectively.

[0014] As used herein, the term "resin" or "polymer" refers to a compound having a weight-average molecular weight of 2000 or more. Here, the weight-average molecular weight is defined as a polystyrene-equivalent value measured using gel permeation chromatography (GPC) under the following conditions: Equipment: Tosoh Corporation HLC-8320GPC Column: Tosoh TSK-GEL G3000PWXL Column temperature: 35℃ ·Flow rate: 0.5mL / min Calibration curve: Poly sodium acrylate standard manufactured by Sowa Scientific Co., Ltd. Eluent: A mixture of sodium dihydrogen phosphate dodecahydrate / disodium hydrogen phosphate dihydrate (34.5g / 46.2g) diluted to 5000g with purified water. In this specification, "(meth)acrylate" is used to mean either or both of acrylate and methacrylate. "(meth)acryloyl group" is used to mean either or both of acryloyl group and methacryloyl group. "(meth)acrylic" is used to mean either or both of acrylic and methacrylic. As used herein, the term "organic group" means a group containing at least one carbon atom.

[0015] In this specification, "identical" includes a margin of error generally accepted in the technical field. Furthermore, in this specification, terms such as "all," "any," and "entirely" include a margin of error generally accepted in the technical field, such as 99% or more, 95% or more, or 90% or more of the target, in addition to 100% of the target, unless otherwise specified. Furthermore, with regard to angles, "orthogonal" or "perpendicular" means a range of 90°±5°, and "parallel" means a range of 0°±5°. Similarly, unless otherwise specified, angles mean that the difference from the exact angle is within a range of 5 degrees. The difference in the above angles is preferably within 4 degrees, and more preferably within 3 degrees.

[0016] [Conductive film] The conductive film of the present invention has a substrate, a conductive pattern arranged on at least one surface side of the substrate, and a protective layer covering the entire surface of the conductive pattern, and the conductive pattern includes a sensor electrode composed of a thin metal wire, a lead-out wiring electrically connected to the sensor electrode, and a connection terminal electrically connected to the lead-out wiring.

[0017] FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a conductive film according to the present invention. The conductive film 100 shown in Figure 1 has a substrate 1, a conductive pattern 10 arranged on one surface 1a of the substrate 1, a protective layer 30 covering the entire surface of the conductive pattern 10, a conductive pattern 20 arranged on the other surface 2b of the substrate 1, and a protective layer 40 covering the entire surface of the conductive pattern 20. The conductive pattern 10 includes a sensor electrode 11 made of a thin metal wire, a lead-out wiring 13, and an external connection terminal 14. The conductive pattern 20 also includes a sensor electrode 21 made of a thin metal wire, a lead-out wiring (not shown), and a connection terminal (not shown). 1, Ta represents the thickness of the protective layer 30 from the surface of the protective layer 30 to the surface of the sensor electrode 11, Tb represents the thickness of the protective layer 30 from the surface of the protective layer 30 to the surface of the lead-out wiring 13, and Tc represents the thickness of the protective layer 30 from the surface of the protective layer 30 to the surface of the external connection terminal 14 (hereinafter, these are also referred to as "thickness Ta," "thickness Tb," and "thickness Tc," respectively). In the conductive film 100 according to the present invention, the thickness Ta is 0.5 μm or more, and the thickness Tc is 3.0 μm or less. 1 shows three thin metal wires constituting sensor electrode 11 and two thin metal wires constituting sensor electrode 21, the arrangement and number of thin metal wires in the sensor electrodes are not limited to the illustrated form. Similarly, the arrangement and number of wires in lead-out wiring 13 and external connection terminal 14 are not limited to the illustrated form.

[0018] In the conductive film according to the present invention, the protective layer contains a resin (hereinafter also referred to as "specific resin") having a repeating unit A derived from a monofunctional (meth)acrylate having a cyclic structure and a repeating unit B derived from a polyfunctional (meth)acrylate, and the protective layer has a glass transition temperature Tg of 50 to 130°C, a thickness Ta of 0.5 μm or more, and a thickness Tc of 3.0 μm or less, thereby improving the sulfurization resistance of the sensor electrode and improving the conductivity of the connection terminal after thermocompression bonding with a flexible printed wiring board.

[0019] Although the details of why the protective layer exhibits the above-mentioned effects are not entirely clear, the inventors speculate as follows. Note that the following speculation does not limit the mechanism by which the effects are obtained. In other words, even if the effects are obtained by a mechanism other than the one described below, a conductive film having the above configuration is included in the scope of the present invention. Conventionally, a technique for providing sulfuration resistance to sensor electrodes in conductive films used in electronic devices such as touch panels by disposing a protective layer on the surface of the conductive pattern has been known. The protective layer prevents sulfur compounds from penetrating into the sensor electrode from surrounding materials or the environment, reacting with the thin metal wires that make up the sensor electrode to form sulfides, which would reduce the sensor electrode's conductivity. Covering the entire surface of the conductive pattern, including not only the sensor electrode but also the lead-out wiring and external connection terminals, with the protective layer can further improve the sensor electrode's sulfuration resistance. However, covering the entire surface of the conductive pattern with a protective layer to improve sulfuration resistance can sometimes reduce the conductivity between the external connection terminals and flexible printed circuits (FPCs). This is thought to be due to the fact that the protective layer, which contains components that inhibit the penetration of sulfur compounds, is difficult to soften during thermocompression bonding of the conductive film and the FPC. This results in a large amount of the protective layer remaining on the surface of the external connection terminals after thermocompression bonding, resulting in reduced conductivity. In response to this, the inventors speculate that by setting the Tg of the protective layer below a predetermined temperature and the thickness of the protective layer below a predetermined value, a sufficient amount of the protective layer to ensure conductivity is removed from the surface of the external connection terminal during thermocompression bonding with the FPC, thereby improving the conductivity between the conductive film and the FPC. Furthermore, by setting the Tg of the protective layer above a predetermined temperature and the thickness of the protective layer above a predetermined value, the sulfurization resistance of the sensor electrode is improved. Furthermore, by using a copolymer of a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate having a cyclic structure in the molecular skeleton as the resin contained in the protective layer, the glass transition temperature Tg of the protective layer can be lowered while suppressing the penetration of sulfur compounds, thereby improving the conductivity.

[0020] Each component of the conductive film of the present invention will be described in detail below. In this specification, the expression "the effect of the present invention is excellent" means that the sensor electrode is excellent in either or both of the sulfuration resistance and FPC connectivity.

[0021] [Base material] The substrate is a member that has the function of supporting the sensor electrodes. The type of substrate is not particularly limited, and examples thereof include resin substrates, glass substrates, and metal substrates, with resin substrates being preferred. As the substrate, a flexible substrate is preferred in terms of providing excellent bending properties for the conductive film. Examples of flexible substrates include the above-mentioned resin substrates. The thickness of the substrate is not particularly limited and is often 10 to 500 μm. When the conductive film is applied to a touch panel and the substrate surface is used as the touch surface, the thickness of the substrate may exceed 500 μm.

[0022] Examples of materials constituting the substrate include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), diacetate resins, triacetate resins, acrylic resins, polycarbonate resins, triacetyl cellulose, polystyrene, polyolefins, polyurethane resins, polyvinyl chloride, polyimide resins, and polyamide resins. Among these, PET, polycycloolefin, and polycarbonate resins are preferred, and PET is more preferred in terms of excellent adhesion to the conductive pattern and ease of production.

[0023] The total light transmittance of the substrate is preferably 85 to 100%. The total light transmittance is measured according to "Plastics - Determination of total light transmittance and total light reflectance" specified in JIS (Japanese Industrial Standards) K 7375:2008.

[0024] The substrate may have an undercoat layer. The undercoat layer is disposed on at least one surface of the substrate. In terms of further improving the adhesion between the substrate and the conductive pattern, it is preferable that the undercoat layer be disposed between the substrate and the conductive pattern. The undercoat layer may contain a resin (binder resin). The resin functions as a binder for the undercoat layer. The resin contained in the undercoat layer may be used alone or in combination of two or more. The type of resin is not particularly limited, and known resins can be used. Examples of resins include polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, and polythiolpolyene resins, with acrylic resins being preferred. The weight average molecular weight of the resin is, for example, 2,000 to 500,000, and preferably 3,000 to 100,000.

[0025] The method for forming the undercoat layer is not particularly limited, and examples thereof include a method in which a composition for forming an undercoat layer containing a resin binder is applied to a substrate, and if necessary, a heat treatment is performed. The composition for forming an undercoat layer may contain a solvent if necessary. Examples of the solvent include water and organic solvents. Examples of the organic solvent include known organic solvents such as alcohol-based solvents, ether-based solvents, ester-based solvents, ketone-based solvents, halogen-based solvents, and hydrocarbon-based solvents. The thickness of the undercoat layer is not particularly limited, but is preferably 0.02 to 0.3 μm, more preferably 0.03 to 0.2 μm, in order to provide better adhesion of the conductive pattern to the substrate.

[0026] [Conductive pattern] The conductive pattern is arranged on at least one surface side of the substrate and includes a sensor electrode made of thin metal wire, a lead-out wiring electrically connected to the sensor electrode, and an external connection terminal electrically connected to the lead-out wiring.

[0027] FIG. 2 is a plan view schematically showing an example of the configuration of the conductive pattern of the conductive film of the present invention. In the illustrated conductive film 100, a conductive pattern 10 including a plurality of sensor electrodes 11, a plurality of electrode connection terminals 12, a plurality of lead-out wirings 13, and a plurality of external connection terminals 14 is formed on one surface 1a of the substrate 1. In addition, a conductive pattern 20 including a plurality of sensor electrodes 21, a plurality of electrode connection terminals 22, a plurality of lead-out wirings 23, and a plurality of external connection terminals 24 is formed on the other surface 1b of the substrate 1.

[0028] In the figure, the multiple sensor electrodes 11 all extend along the Y direction on the surface 1a of the substrate 1. The multiple sensor electrodes 11 are also arranged at intervals from one another in the X direction, which is perpendicular to the Y direction. The multiple electrode connection terminals 12 are each connected to one end of the multiple sensor electrodes 11 in the Y direction. One end of each of the multiple lead-out wirings 13 is connected to a corresponding electrode connection terminal 12, and the other end is connected to an external connection terminal 14. The multiple external connection terminals 14 are each connected to the multiple lead-out wirings 13. Each of the plurality of sensor electrodes 21 extends along the X direction on the surface 1b of the substrate 1. The plurality of sensor electrodes 21 are also arranged at intervals in the Y direction. The plurality of electrode connection terminals 22 are connected to one end of the plurality of sensor electrodes 21 in the X direction. Each of the plurality of lead-out wirings 23 has one end connected to a corresponding electrode connection terminal 22 and the other end connected to an external connection terminal 24. The plurality of external connection terminals 24 are connected to the plurality of lead-out wirings 23, respectively.

[0029] In the illustrated conductive film 100, the sensor region R1 is a region surrounding the sensor electrodes 11 and 21 arranged on the surface of the substrate 1. The peripheral region R2 is a region outside (on the periphery of) the sensor region R1, and the lead-out wirings 13 and 23 and the external connection terminals 14 and 24 are arranged in the peripheral region R2. 1 and 2, the conductive patterns 10 and 20 are arranged on the surfaces 1a and 1b of the substrate 1, respectively, but the conductive patterns may be arranged on only one surface of the substrate. Also, the conductive patterns may include only one sensor electrode, one lead-out wiring, and one external connection terminal.

[0030] <Sensor electrode> The sensor electrodes will now be described in more detail. The sensor electrode is made of thin metal wire and functions as a detection electrode that detects touch operations. The sensor electrode may have a predetermined pattern formed by thin metal wires. The pattern to be formed is not particularly limited, and is preferably a shape selected from the group consisting of triangles such as equilateral triangles, isosceles triangles, and right-angled triangles, quadrilaterals such as squares, rectangles, rhombus, parallelograms, and trapezoids, (regular) n-gons such as (regular) hexagons and (regular) octagons, circles, ellipses, stars, and geometric shapes combining these shapes, and more preferably a mesh shape (mesh pattern). The mesh shape means a shape including a plurality of openings (lattice) formed by intersecting thin metal wires, as shown in FIG. FIG. 3 is a plan view showing an example of the configuration of a sensor electrode included in the conductive film of the present invention. In the sensor electrode 11 shown in FIG. 3, the openings 16 are formed in a mesh pattern that is a square with a side length of L, using thin metal wires 15.

[0031] The shape of the mesh pattern of the sensor electrode is not limited to a square and may be other shapes. Examples of the shape of the mesh pattern of the sensor electrode include the above-mentioned figures. Furthermore, the shape of one side of the opening may be straight, curved, or arc-shaped. When the shape is arc-shaped, for example, two opposing sides may be arc-shaped convex outward, and the other two opposing sides may be arc-shaped convex inward. Furthermore, the shape of each side may be a wavy line consisting of a continuous arc convex outward and an arc convex inward. Of course, the shape of each side may be a sine curve. The mesh pattern is not particularly limited, and may be a random pattern or a regular pattern, or may be a regular mesh pattern in which multiple congruent shapes are repeatedly arranged.

[0032] The mesh pattern of the sensor electrode is preferably a regular mesh pattern with diamond-shaped or square-shaped openings of the same shape. From the viewpoint of visibility, the length L of one side of the opening is preferably 5 to 1500 μm, more preferably 10 to 1000 μm. When the length L of one side of the opening is within the above range, it is possible to maintain good transparency, and when a touch panel having a conductive film is attached to the display surface of an image display device, the displayed image can be viewed without any sense of incongruity. The aperture ratio of the mesh pattern of the sensor electrode is preferably 90% or more, more preferably 95% or more, in terms of visible light transmittance. There is no particular upper limit, but it can be less than 100%. The aperture ratio corresponds to the area ratio of the openings, excluding the thin metal wires, in the region where the sensor electrode is provided to the entire region where the sensor electrode is provided. The shape of the mesh pattern of the sensor electrode can be observed and measured using an optical microscope.

[0033] The width of the thin metal wires constituting the sensor electrode is preferably 10 μm or less, more preferably 5 μm or less, from the viewpoint of superior visibility. There is no particular lower limit, but the width is preferably 0.1 μm or more, more preferably 0.5 μm or more, from the viewpoint of superior conductivity. The thickness of the thin metal wire, ie, the thickness of the sensor electrode, is not particularly limited, but is preferably 0.1 to 10 μm, more preferably 0.3 to 5 μm, from the viewpoint of the balance between conductivity and prevention of breakdowns such as wire breakage. The width and thickness of the above-mentioned thin metal wires are measured by the following method. The conductive film is cut along a plane perpendicular to the direction in which the target thin metal wires extend, and the resulting cut surface is observed using a scanning electron microscope (SEM). The measured values ​​of the thin metal wires are obtained from the obtained observation image. Five arbitrary locations on the thin metal wire are selected, and the measured values ​​are measured by the above-mentioned method. The average values ​​obtained by arithmetically averaging the measured values ​​are used as the width and thickness of the thin metal wires.

[0034] The thin metal wires contain a metal. The metal contained in the thin metal wire is preferably silver (metallic silver), copper (metallic copper), gold (metallic gold), nickel (metallic nickel), palladium (metallic palladium), or a mixture of two or more of these, as they have better conductivity. Silver, copper, or a mixture thereof is more preferred, and silver is even more preferred. It is particularly preferred that all the metals contained in the thin metal wire are silver. When all the metals are silver, the occurrence of wire breakage failures in the thin metal wire is reduced. The form of the metal in the thin metal wire is not limited, and examples include a particulate form and a form in which the metal is dispersed in layers in the thin metal wire.

[0035] The thin metal wires may contain components other than metal. The thin metal wires may be metallic silver wires suitable for forming a mesh pattern and contain a polymer binder such as gelatin and acrylic-styrene latex. When the thin metal wires contain a polymer binder, the metal particles may be present in a dispersed state in the polymer, or the metal particles may be aggregated in the polymer to form aggregates. The type of polymer is not particularly limited, and known polymers can be used. The thin metal wires may be thin metal wires made of aluminum, copper, silver, molybdenum, titanium, or alloys thereof, or may have a laminated structure of these metals, such as a laminated structure in which a molybdenum layer, a copper layer, and a molybdenum layer are arranged in this order, or a laminated structure in which a molybdenum layer, an aluminum layer, and a molybdenum layer are arranged in this order. The thin metal wires may include metal oxide particles, metal pastes such as silver paste and copper paste, and metal nanowire particles such as silver nanowires and copper nanowires.

[0036] <Exit wiring> The lead wires are members that are electrically connected to the sensor electrodes and the external connection terminals, respectively. Figure 4 shows an example of the configuration of the sensor electrodes and lead wires that the conductive pattern has. The conductive pattern 10 shown in Fig. 4 includes a sensor electrode 11, an electrode connection terminal 12, and a lead-out wiring 13. The sensor electrode 11 is composed of a plurality of thin metal wires MW formed in the sensor region, and the thin metal wires MW form a diamond-shaped mesh pattern MP. In addition, an electrode connection terminal 12 is formed at one end of the sensor electrode 11. One end of the lead-out wiring 13 is disposed near one end of the sensor electrode 11 and connected to the electrode connection terminal 12. This electrically connects the lead-out wiring 13 to the sensor electrode 11. The other end of the lead-out wiring 13 is connected to an external connection terminal (not shown).

[0037] The material constituting the lead wires, including preferred embodiments, may be the same as the material constituting the above-mentioned thin metal wires. Furthermore, the material constituting the lead wires is preferably the same as the material constituting the thin metal wires of the sensor electrodes. It is more preferable that the sensor electrodes, the lead wires, and the conductive pattern including the external connection terminals arranged on one surface of the substrate are simultaneously formed using the same material.

[0038] The line width of the lead wiring is not particularly limited, but is preferably 2 to 100 μm, more preferably 3 to 20 μm, from the viewpoint of the balance between conductivity and narrowing of the peripheral region. The thickness of the lead wiring is not particularly limited, but from the viewpoint of the balance between conductivity and prevention of breakdowns such as wire breakage, it is preferably 0.1 to 10 μm, more preferably 0.3 to 5 μm.

[0039] <External connection terminal> The external connection terminals are electrically connected to the lead wiring and are used for electrically connecting to an external device (such as an FPC.) The external connection terminals are connected to the FPC via, for example, an anisotropic conductive film (ACF). In the conductive film of the present invention, the protective layer contains a resin having repeating units A and B, the glass transition temperature of the protective layer is 50 to 130°C, and the thickness Tc of the protective layer is 3.0 μm or less, thereby improving the conductivity between the external connection terminal and the FPC and providing a superior function of transmitting the electrical signal detected by the sensor electrode to an external device.

[0040] FIG. 5 shows an example of the configuration of the external connection terminals of the conductive pattern. 5 has a rectangular outer shape with a length L along its extension direction and a width W along a direction perpendicular to the extension direction. Inside the outer shape of the external connection terminal 14, the external connection terminal 14 includes thin metal wires 17 that are thinner than the lead-out wiring 13 and form a mesh pattern.

[0041] The material constituting the external connection terminals, including preferred embodiments, may be the same as the material constituting the above-mentioned thin metal wires. Furthermore, the material constituting the external connection terminals is preferably the same as the material constituting the thin metal wires of the sensor electrodes, and more preferably the same as the material constituting the thin metal wires of the sensor electrodes and the material constituting the lead-out wiring.

[0042] When the external connection terminals are formed in a mesh pattern, the line width of the thin metal wires that make up the mesh pattern is not particularly limited, but is preferably 0.5 to 20 μm, more preferably 1 to 10 μm. The thickness of the external connection terminal is not particularly limited, but from the viewpoint of the balance between conductivity and prevention of failures such as disconnection, it is preferably 0.1 to 10 μm, more preferably 0.3 to 5 μm.

[0043] The conductive pattern may include other conductive members in addition to the sensor electrodes, lead wiring, and external connection terminals, such as dummy electrodes and alignment marks for adjusting the positions of members laminated on the conductive film.

[0044] [Protective layer] The conductive film according to the present invention has a protective layer that covers the entire surface of the conductive pattern. Here, "covering the entire surface of the conductive pattern" means that, when the conductive film is observed from a direction perpendicular to the main surface of the conductive film, components included in the conductive pattern, such as sensor electrodes, lead wires, and external connection terminals, are arranged within the region where the protective layer is formed. The protective layer may or may not be in direct contact with the conductive pattern.

[0045] The protective layer contains a resin (hereinafter also referred to as "specific resin") having a repeating unit A derived from a monofunctional (meth)acrylate having a cyclic structure and a repeating unit B derived from a polyfunctional (meth)acrylate. The specific resin is a copolymer obtained by copolymerizing a plurality of monomers including at least a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate having a cyclic structure. The specific resin may be any of a random copolymer, a block copolymer, and a graft copolymer.

[0046] <Repeating unit A> The repeating unit A is a repeating unit derived from a monofunctional (meth)acrylate having a cyclic structure. The monofunctional (meth)acrylate means a compound having only one (meth)acryloyloxy group.

[0047] The cyclic structure in the monofunctional (meth)acrylate having a cyclic structure is not particularly limited, and examples thereof include an aliphatic ring and an aromatic ring. The ring of the cyclic structure may be a monocyclic ring or a fused ring, but is preferably a monocyclic ring. In terms of the effects of the present invention being more excellent, the cyclic structure is preferably a monocyclic structure consisting of only a single ring, or a structure in which multiple monocyclic structures are linked via a single bond or a linking group, and more preferably a monocyclic structure or a structure in which multiple monocyclic structures (more preferably two monocyclic structures) are linked via a single bond. The ring in the cyclic structure may be either a hydrocarbon ring whose ring member atoms are carbon atoms only, or a heterocyclic ring containing a heteroatom as a ring member atom, with a hydrocarbon ring being preferred. As the cyclic structure, a monocyclic structure consisting of an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring, or a structure in which a plurality of (more preferably two) monocyclic structures consisting of an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring are linked via a single bond is particularly preferred.

[0048] Examples of the aliphatic ring include a cyclohexane ring, a bicyclo[2.2.1]heptane ring, a dicyclopentane ring, and a dicyclopentene ring. Examples of the aromatic ring include a benzene ring and a naphthalene ring.

[0049] In the monofunctional (meth)acrylate having a cyclic structure, the cyclic structure may have a substituent. Examples of the substituent include an alkyl group (e.g., an alkyl group having 1 to 6 carbon atoms), a hydroxy group, an alkoxyl group (e.g., an alkoxyl group having 1 to 6 carbon atoms), and a halogen atom (e.g., a fluorine atom, a chlorine atom, and a bromine atom). It is preferable that the cyclic structure has no substituent or has an alkyl group having 1 to 6 carbon atoms as a substituent. The monofunctional (meth)acrylate having a cyclic structure may have, in the molecule, a bond selected from an ester bond different from the ester bond of the (meth)acryloyloxy group, a urethane bond, and an ether bond. It is preferable that the monofunctional (meth)acrylate having a cyclic structure does not have any ester bond different from the ester bond of the (meth)acryloyloxy group or any urethane bond.

[0050] The number of carbon atoms in the monofunctional (meth)acrylate having a cyclic structure is preferably 9 to 17, more preferably 9 to 16, and even more preferably 9 to 15. The number of carbon atoms includes the number of carbon atoms contained in the (meth)acryloyl group. Furthermore, the monofunctional (meth)acrylate having a cyclic structure is preferably a monofunctional acrylate having a cyclic structure and one acryloyloxy group.

[0051] Specific examples of (meth)acrylates having a cyclic structure include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, nonylphenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, nonylphenoxyethyl tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrafurfuryl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, propylene oxide-modified nonylphenol (meth)acrylate, and 2-(2-biphenylyloxy)ethyl (meth)acrylate. Among these, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and 2-(2-biphenylyloxy)ethyl (meth)acrylate are preferred, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and 2-(2-biphenylyloxy)ethyl (meth)acrylate are more preferred, and cyclohexyl acrylate and 2-(2-biphenylyloxy)ethyl acrylate are even more preferred.

[0052] The specific resin may have only one type or two or more types of repeating unit A. The content of repeating unit A is, for example, 1 to 99 mol % relative to all repeating units of the specific resin, and is preferably 10 to 90 mol %, more preferably 20 to 80 mol %, from the viewpoint of achieving a more excellent effect of inhibiting the penetration of sulfur compounds.

[0053] The structure and content of the repeating unit of the specific resin contained in the protective layer can be determined by nuclear magnetic resonance spectroscopy ( 1 The thickness can be determined by measuring a sample of the protective layer by 1 H-NMR.

[0054] <Repeating unit B> The repeating unit B is a repeating unit derived from a polyfunctional (meth)acrylate. The polyfunctional (meth)acrylate means a compound having two or more (meth)acryloyloxy groups.

[0055] The number of (meth)acryloyloxy groups that the polyfunctional (meth)acrylate has is not particularly limited as long as it is two or more, and may be, for example, two to six.

[0056] Examples of bifunctional (meth)acrylates having two (meth)acryloyl groups include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5 pentanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3 propane di(meth)acrylate, dimethylol tricyclodecane di(meth)acrylate, and propylene glycol di(meth)acrylate. acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, 1,3 butanediol di(meth)acrylate, dimethylol dicyclopentane di(meth)acrylate, hexaethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2'-bis(4-acryloxydiethoxyphenyl)propane, bisphenol A tetraethylene glycol diacrylate, and bisphenoxyethanol fluorene diacrylate.

[0057] Examples of trifunctional (meth)acrylates having three (meth)acryloyl groups include trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, caprolactone-modified tris(acryloxyethyl)isocyanurate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, alkyl-modified dipentaerythritol tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, ethylene oxide-modified glycerol triacrylate, propylene oxide-modified glycerol triacrylate, ε-caprolactone-modified trimethylolpropane triacrylate, and pentaerythritol triacrylate.

[0058] Examples of tetrafunctional or higher (meth)acrylates having four or more (meth)acryloyl groups include ditrimethylolpropane tetra(meth)acrylate, pentaerythritol ethoxy tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, alkyl-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and polypentaerythritol polyacrylate.

[0059] The polyfunctional (meth)acrylate is preferably a di- to tetrafunctional (meth)acrylate, more preferably a di- or trifunctional (meth)acrylate, and even more preferably a difunctional (meth)acrylate, in that the effects of the present invention are more excellent. When the specific resin has a repeating unit derived from a bifunctional (meth)acrylate as the repeating unit B, the specific resin may have a repeating unit derived from a trifunctional or higher functional (meth)acrylate, but preferably does not substantially contain a repeating unit derived from a trifunctional or higher functional (meth)acrylate. "Substantially does not contain a repeating unit derived from a trifunctional or higher functional (meth)acrylate" means that the content of repeating units derived from a trifunctional or higher functional (meth)acrylate is 1 mol% or less, more preferably 0.5 mol% or less, and even more preferably 0 mol%, based on the total repeating units of the specific resin.

[0060] Furthermore, the two or more (meth)acryloyl groups possessed by the polyfunctional (meth)acrylate may each independently be either an acryloyl group or a methacryloyl group, and it is preferable that all of them are acryloyl groups.

[0061] In the case of a bifunctional (meth)acrylate, the number of atoms Nb connecting the two (meth)acryloyl groups is preferably 5 to 11, more preferably 5 to 10, and even more preferably 5 to 9, in that the effect of inhibiting the penetration of sulfur compounds is more excellent. The number of atoms, Nb, is defined as follows: First, the structure of the bifunctional (meth)acrylate is divided into two (meth)acryloyl groups and a linking structure connecting the two (meth)acryloyl groups. In this linking structure, the oxygen atom connecting one of the two (meth)acryloyl groups is the starting point, and the oxygen atom connecting the other of the two (meth)acryloyl groups is the end point. Next, a path is hypothesized that follows the atoms and interatomic bonds contained in the linking structure from the starting point to the end point within the linking structure. Here, if multiple paths can be hypothesized from the same linking structure, the path with the smallest number of atoms included in the path is selected. The number of atoms, Nb, is the number of atoms included in the path hypothesized in this way, and refers to the number of atoms including the oxygen atom at the starting point and the oxygen atom at the end point.

[0062] The number of atoms, Nb, can be easily determined from the structural formula representing the bifunctional (meth)acrylate. For example, the number of atoms Nb in neopentyl glycol diacrylate (NPDA) represented by the following structural formula is 5. Also, the number of atoms Nb in dimethylol tricyclodecane diacrylate (A-DCP) represented by the following structural formula is 9.

[0063] [ka]

[0064] Among the polyfunctional (meth)acrylates, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5 pentanediol di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, and dimethyloldicyclopentane diacrylate are preferred, and 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and dimethyloltricyclodecane di(meth)acrylate are more preferred.

[0065] The specific resin may have only one type or two or more types of repeating unit B. The content of repeating unit B is, for example, 1 to 99 mol % relative to all repeating units of the specific resin, and is preferably 10 to 90 mol %, more preferably 20 to 80 mol %, from the viewpoint of being more effective in inhibiting the penetration of sulfur compounds.

[0066] The specific resin may have a repeating unit other than the repeating units A and B. Examples of the other repeating unit include a repeating unit derived from a monofunctional (meth)acrylate that does not have a cyclic structure, and a repeating unit derived from a monomer other than (meth)acrylate that is copolymerizable with (meth)acrylate.

[0067] Monofunctional (meth)acrylates that do not have a cyclic structure are compounds that do not have a cyclic structure and have only one (meth)acryloyloxy group. Examples of monofunctional (meth)acrylates that do not have a cyclic structure include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, and lauryl (meth)acrylate; and hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of monomers copolymerizable with (meth)acrylates other than (meth)acrylates include compounds having a carbon-carbon double bond, such as ethylene, propylene, butadiene, and styrene.

[0068] The total content of repeating units A and B is preferably 50 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, based on the total amount of repeating units contained in the specific resin. The total content of repeating units A and B may be 100 mol% based on the total amount of repeating units contained in the specific resin. The specific resin preferably has only the repeating unit A and the repeating unit B.

[0069] The content of the specific resin in the protective layer is preferably 10% by mass or more, more preferably 20% by mass or more, based on the total amount of the protective layer. There is no particular upper limit, and the content of the specific resin may be 100% by mass based on the total amount of the protective layer.

[0070] The protective layer may contain components other than the specific resin, such as other resins such as polyester resins and urethane resins, and additives. Examples of the additives include leveling agents, surface lubricants, antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, and fillers.

[0071] <Properties of the protective layer> In the conductive film of the present invention, the protective layer has a glass transition temperature Tg of 50 to 130°C. The glass transition temperature Tg of the protective layer is preferably from 60 to 120°C, more preferably from 70 to 80°C, in terms of better effects of the present invention. The glass transition temperature Tg of the protective layer is measured using a differential scanning calorimeter (DSC) (for example, the X-DSC7000 manufactured by Hitachi High-Tech Science Corporation) by a method conforming to JIS K-7121-1987. More specifically, the protective layer of the conductive film is subjected to the following temperature programs 1 to 4, and the midpoint glass transition temperature measured in temperature program 3 is adopted as the glass transition temperature Tg of the protective layer. Temperature program 1: Start temperature 30°C, end temperature 250°C, heating rate 10°C / min. ·Temperature program 2: Start temperature 250℃, end temperature -20℃, cooling rate 10℃ / min. Temperature program 3: Start temperature -20℃, end temperature 250℃, heating rate 10℃ / min. ·Temperature program 4: Start temperature 250℃, end temperature 30℃, cooling rate 20℃ / min.

[0072] In the conductive film of the present invention, the protective layer has a thickness Ta of 0.5 μm or more from the surface of the protective layer to the surface of the sensor electrode, and a thickness Tc of 3.0 μm or less from the surface of the protective layer to the surface of the external connection terminal. The thickness Ta is not particularly limited as long as it is 0.5 μm or more, but is preferably 0.5 to 3.0 μm, and more preferably 0.5 to 1.5 μm in terms of better effects of the present invention. The thickness Tc is not particularly limited as long as it is 3.0 μm or less, but is preferably 0.5 to 3.0 μm, and more preferably 0.5 to 1.5 μm in terms of better effects of the present invention. The thickness Tb of the protective layer from the surface of the protective layer to the surface of the lead wire is preferably 0.5 to 3.0 μm, more preferably 0.5 to 1.5 μm. The thicknesses Ta, Tb, and Tc at each position may be the same or different, but are preferably the same.

[0073] The thickness Ta of the protective layer is measured in accordance with the method for measuring the thickness of the thin metal wires that make up the sensor electrode. That is, the conductive film is cut in the thickness direction in the region where the sensor electrode is located, and the resulting cut surface is observed using a scanning electron microscope (SEM), thereby determining the thickness Ta of the protective layer. The thicknesses Tb and Tc of the protective layer are measured in the same manner as the thickness Ta.

[0074] The conductive film may have other members in addition to the substrate, the conductive pattern, and the protective layer.

[0075] [Method for producing conductive film] The method for producing the conductive film is not particularly limited as long as it can produce a conductive film having the above-mentioned configuration, and any known method can be used. For example, the method for producing the conductive film includes a conductive pattern forming step of forming the above-mentioned conductive pattern on the surface of the substrate, and a protective layer forming step of forming the above-mentioned protective layer on the surface on which the conductive pattern is arranged. Hereinafter, a method for producing a conductive film including a conductive pattern forming step and a protective layer forming step will be described.

[0076] <Conductive pattern formation process> The conductive pattern forming step is a step of forming a conductive pattern including the sensor electrodes, lead wires, and external connection terminals on at least one surface side of the substrate. As a method for forming a conductive pattern on the surface of a substrate, for example, a sputtering method, a plating method, a silver halide method, a printing method, or the like can be appropriately used.

[0077] A method for forming a conductive pattern using a sputtering method will be described. First, a copper foil layer is formed by sputtering, and then copper wiring is formed from the copper foil layer by photolithography, thereby forming a conductive pattern. Instead of sputtering, the copper foil layer can also be formed by so-called vapor deposition. As the copper foil layer, in addition to sputtered copper foil or vapor-deposited copper foil, electrolytic copper foil can also be used. More specifically, the process for forming copper wiring described in JP 2014-029614 A can be used.

[0078] A method for forming a conductive pattern using a plating method will be described. For example, a metal plating film is formed on an electroless plating base layer by electroless plating. This metal plating film can be used as the conductive pattern. In this case, the conductive pattern is formed by forming a pattern of a catalyst ink containing at least metal fine particles on a substrate, and then immersing the substrate in an electroless plating bath to form a metal plating film. More specifically, the method for producing a metal-coated substrate described in JP 2014-159620 A can be used.

[0079] The conductive pattern can be formed by forming a pattern of a resin composition having functional groups capable of interacting with at least a metal catalyst precursor on a substrate, applying a catalyst or catalyst precursor, and immersing the substrate in an electroless plating bath to form a metal plating film. More specifically, the method for producing a metal-coated substrate described in JP 2012-144761 A can be applied.

[0080] A method for forming a conductive pattern using a silver salt method will be described. First, a silver salt emulsion layer containing silver halide is exposed to light using an exposure pattern corresponding to the conductive pattern, and then a development process is performed to form the conductive pattern. More specifically, the methods for producing thin metal wires described in JP 2012-006377 A, JP 2014-112512 A, JP 2014-209332 A, JP 2015-022397 A, JP 2016-192200 A, and WO 2016 / 157585 A can be used.

[0081] A method for forming a conductive pattern by a printing method will be described. First, a conductive paste containing conductive powder is applied to a substrate in the same pattern as the conductive pattern, and then a heat treatment is performed to form the conductive pattern. Pattern formation using the conductive paste is performed by, for example, an inkjet method or a screen printing method. More specifically, the conductive paste described in JP 2011-028985 A can be used as the conductive paste.

[0082] <Protective layer formation process> The protective layer forming step is a step of forming a protective layer on the surface of the base material on which the conductive pattern has been formed in the conductive pattern forming step, so as to cover the entire surface of the conductive pattern. The method for forming the protective layer is not particularly limited, and examples thereof include a method (coating method) in which a protective layer-forming composition containing a specific resin or a precursor of a specific resin is applied to the surface of a substrate on which a conductive pattern has been formed, and the coating film is subjected to treatments such as curing treatment, heating treatment, and drying treatment as necessary to form a protective layer, and a method (transfer method) in which a protective layer is formed on a temporary substrate and then transferred to the surface of the substrate on which a conductive pattern has been formed. The coating method is preferred because it is easy to control the thickness of the protective layer. The process of forming a protective layer by a coating method will be described below.

[0083] The protective layer-forming composition used to form the protective layer may be, for example, a composition containing a specific resin or a precursor of the specific resin. Examples of the precursor of the specific resin include a monofunctional (meth)acrylate having a cyclic structure from which the repeating unit B is derived and a polyfunctional (meth)acrylate from which the repeating unit A is derived.

[0084] The protective layer-forming composition may further contain a polymerization initiator. When the protective layer-forming composition contains a precursor of the specific resin, it preferably contains a polymerization initiator. The polymerization initiator may be either a photopolymerization initiator or a thermal polymerization initiator, and is selected according to the method of curing treatment. Among them, a photopolymerization initiator is preferred. The type of photopolymerization initiator is not particularly limited, and known photopolymerization initiators (radical photopolymerization initiators and cationic photopolymerization initiators) can be used. The polymerization initiators may be used alone or in combination of two or more. When the composition for forming a protective layer contains a polymerization initiator, the content of the polymerization initiator is preferably 0.1 to 10 mass %, more preferably 2 to 5 mass %, based on the total solid content in the composition for forming a protective layer.

[0085] The protective layer-forming composition may contain a solvent from the viewpoint of ease of handling, but preferably does not contain a solvent from the viewpoint of suppressing VOCs (volatile organic compounds) and shortening takt time. Examples of the solvent contained in the protective layer-forming composition include water and organic solvents.

[0086] Examples of methods for applying the protective layer-forming composition include coating methods using a gravure coater, comma coater, bar coater, knife coater, die coater, and roll coater, inkjet methods, and screen printing methods.

[0087] The protective layer is formed by curing the coating film of the protective layer-forming composition. The curing treatment may be either a photocuring treatment or a thermal curing treatment. Among these, a photocuring treatment is preferred because it reduces damage to the substrate and shortens the takt time. Examples of photocuring methods include irradiation with actinic rays or radiation. Irradiation with actinic rays includes irradiation with UV (ultraviolet) lamps and visible light. Examples of light sources include mercury lamps, metal halide lamps, xenon lamps, chemical lamps, and carbon arc lamps. Examples of radiation include electron beams, X-rays, and ion beams. By exposing the coating film to light, the polymerizable groups contained in the acrylate compound in the coating film are activated, crosslinking occurs between the compounds, and the coating film hardens. The exposure energy is 10 to 8000 mJ / cm. 2 It is sufficient if the intensity is around 50 to 3000 mJ / cm2 is preferred.

[0088] A drying step may be carried out to dry the coating film of the protective layer-forming composition, which can remove the solvent and unreacted acrylate compound contained in the coating film. An example of the drying treatment is a treatment in which dry air is supplied to the coating film. The average wind speed of the drying air is preferably 5 to 30 m / sec, more preferably 7 to 25 m / sec, and even more preferably 9 to 20 m / sec. The temperature of the drying air is preferably from 50 to 200°C, more preferably from 70 to 150°C, and even more preferably from 90 to 120°C. The drying time is preferably from 30 to 300 seconds, more preferably from 60 to 180 seconds. From the viewpoint of productivity, it is preferable that the composition for forming a protective layer does not contain a solvent and that a drying step is not performed.

[0089] [Uses of conductive film] The conductive film obtained as described above can be used in a variety of applications, including touch panels (or touch panel sensors), semiconductor chips, various electric wiring boards, FPCs (Flexible Printed Circuits), COFs (Chip on Film), TABs (Tape Automated Bonding), antennas, multilayer wiring boards, and motherboards. Among these, touch panels (capacitive touch panels) having a conductive film are preferred applications of the conductive film of the present invention. In a touch panel having a conductive film, the sensor electrode described above can effectively function as a detection electrode. When the conductive film is used in a touch panel, examples of the display panel that can be used in combination with the conductive film include a liquid crystal panel and an OLED (organic light emitting diode) panel, and a combination with an OLED panel is preferred.

[0090] The conductive film may have a conductive portion having a different configuration from the conductive pattern disposed on the surface of the substrate. This conductive portion may be electrically connected to the sensor electrode and be conductive. Examples of the conductive portion include peripheral wiring that applies a voltage to the sensor electrode and alignment marks that adjust the position of the conductive film and the member to be laminated.

[0091] Other uses of the conductive film include, for example, electromagnetic wave shielding that blocks electromagnetic waves such as radio waves and microwaves (ultra-high frequency waves) generated by electronic devices such as personal computers and workstations, and prevents static electricity. Such electromagnetic wave shielding can be used not only in personal computers, but also in electronic devices such as video recording equipment and electronic medical devices. The conductive film can also be used for transparent heating elements.

[0092] The conductive film may be used in the form of a laminate including the conductive film and other members such as an adhesive sheet and a release sheet during handling and transportation. The release sheet functions as a protective sheet to prevent scratches on the conductive film during transportation of the laminate. The conductive film may also be handled in the form of a composite having, for example, a conductive film, an adhesive sheet, and a protective sheet in this order.

[0093] The present invention is basically configured as described above. Although the conductive film of the present invention has been described in detail, the present invention is not limited to the above-described embodiment, and various improvements or modifications may be made without departing from the spirit and scope of the present invention. [Example]

[0094] The present invention will be explained in more detail below with reference to examples. Note that the materials, amounts used, ratios, treatment details, and treatment procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[0095] [(Meth)acrylate] The following compounds were used as the monofunctional (meth)acrylate and polyfunctional (meth)acrylate used to form the protective layer.

[0096] <Monofunctional (meth)acrylate> CHA: Cyclohexyl acrylate OPPEA: 2-(2-biphenylyloxy)ethyl acrylate IBXA: Isobornyl acrylate OA: Octyl acrylate (monofunctional (meth)acrylate without a cyclic structure)

[0097] <Polyfunctional (meth)acrylate> NPDA: Neopentyl glycol diacrylate (bifunctional, Nb=5) A-DCP: Dimethyloltricyclodecane diacrylate (bifunctional, Nb=9) A-TMPT: Trimethylolpropane triacrylate (trifunctional) NOD-N: 1,9-nonanediol diacrylate (bifunctional, Nb=9) The specific resin contained in the protective layer formed using the A-DCP has a repeating unit derived from A-DCP in which the number of atoms, Nb, is 9, as follows: 1 This was confirmed by H-NMR measurement.

[0098] [ka] [ka]

[0099] [Example 1] [Preparation of Silver Halide Emulsion] To Solution 1 below, maintained at 38°C and pH 4.5, 90% of each of Solutions 2 and 3 below was added simultaneously over 20 minutes while stirring Solution 1, forming 0.16 μm core particles. Solutions 4 and 5 below were then added to the resulting solution over 8 minutes, and the remaining 10% of Solutions 2 and 3 below was added over 2 minutes, growing the core particles to 0.21 μm. 0.15 g of potassium iodide was then added to the resulting solution, which was then aged for 5 minutes to complete particle formation.

[0100] 1 liquid: 750mL water 8.6g gelatin Sodium chloride 3g 1,3-dimethylimidazolidine-2-thione 20mg Sodium benzenethiosulfonate 10mg Citric acid 0.7g 2 liquid: 300mL water Silver nitrate 150g 3 liquid: 300mL water 38g sodium chloride 32g potassium bromide Potassium hexachloroiridate(III) (0.005%KCl 20% aqueous solution) 5mL Ammonium hexachlororhodate (0.001%NaCl 20% aqueous solution) 7mL 4 liquid: 100mL water Silver nitrate 50g 5 liquid: 100mL water Sodium chloride 13g Potassium bromide 11g Yellow prussic acid 5mg

[0101] The emulsion was then washed using the conventional flocculation method. Specifically, the temperature of the resulting solution was lowered to 35°C, and the pH was lowered using sulfuric acid until the silver halide precipitated (pH 3.6 ± 0.2). Approximately 3 L of the supernatant was removed from the resulting solution (first wash). 3 L of distilled water was then added to the resulting solution, and sulfuric acid was added until the silver halide precipitated. Another 3 L of the supernatant was removed from the resulting solution (second wash). The same procedure as the second wash was repeated once more (third wash), completing the washing and desalting steps. The washed and desalted emulsion was adjusted to pH 6.4 and pAg 7.5, and chemically sensitized to the optimum sensitivity by adding 2.5 g of gelatin, 10 mg of sodium benzenethiosulfonate, 3 mg of sodium benzenethiosulfinate, 15 mg of sodium thiosulfate, and 10 mg of chloroauric acid at 55°C. Then, 100 mg of 1,3,3a,7-tetraazaindene as a stabilizer and 100 mg of Proxel (trade name, manufactured by ICI Co., Ltd.) as a preservative were added to the resulting emulsion. The finally obtained emulsion was a silver chlorobromide cubic grain emulsion containing 0.08 mol % of silver iodide and a silver chlorobromide ratio of 70 mol % of silver chloride and 30 mol % of silver bromide, with an average grain size (equivalent to a sphere) of 200 nm and a coefficient of variation of 9%.

[0102] [Preparation of Photosensitive Layer Forming Composition] The above emulsion was treated with 1,3,3a,7-tetraazaindene (1.2 × 10 -4 mol / mol Ag), hydroquinone (1.2 × 10 -2 mol / mol Ag), citric acid (3.0 × 10 -4 The composition was then adjusted to a pH of 5.6 with citric acid. To the above composition, a polymer latex containing a polymer represented by the following formula (P-1) (hereinafter also referred to as "Polymer 1"), a dispersant consisting of dialkylphenyl PEO (PEO is an abbreviation for polyethylene oxide) sulfate ester, and water (the ratio of the mass of dispersant to the mass of Polymer 1 (mass of dispersant / mass of Polymer 1, unit: g / g) was 0.02, and the solid content was 22% by mass) was added so that the ratio of the mass of Polymer 1 to the total mass of gelatin in the composition (mass of Polymer 1 / mass of gelatin, unit: g / g) was 0.25 / 1, thereby obtaining a polymer latex-containing composition. Here, in the polymer latex-containing composition, the ratio of the mass of gelatin to the mass of silver derived from silver halide (mass of gelatin / mass of silver derived from silver halide, unit: g / g) was 0.11. Furthermore, EPOXY RESIN DY 022 (trade name: manufactured by Nagase ChemteX Corporation) was added as a crosslinking agent. The amount of the crosslinking agent added was determined so that the amount of the crosslinking agent in the silver halide-containing photosensitive layer described below was 0.09 g / m 2 It was adjusted so that In this manner, a composition for forming a photosensitive layer was prepared. Polymer 1 was synthesized with reference to Japanese Patent Nos. 3305459 and 3754745.

[0103] [ka]

[0104] [Formation of Undercoat Layer] The above-mentioned polymer latex was applied to the surface of a 40 μm thick polyethylene terephthalate film (a roll of long film manufactured by Fujifilm Corporation) to form a 0.05 μm thick primer layer. This process was carried out by roll-to-roll, and the following processes (steps) were also carried out by the same roll-to-roll method. The roll width was 1 m and the length was 1000 m.

[0105] [Process H1, Process A1, Process I1] Next, a first silver halide-free layer-forming composition comprising a mixture of the above-mentioned polymer latex and gelatin, the above-mentioned photosensitive layer-forming composition, and a second silver halide-free layer-forming composition comprising a mixture of the above-mentioned polymer latex and gelatin were simultaneously coated in multiple layers on the undercoat layer to form a first silver halide-free layer, a silver halide-containing photosensitive layer, and a second silver halide-free layer on the undercoat layer. The thickness of the first silver halide-free layer was 2.0 μm, the mixture mass ratio of polymer 1 to gelatin in the first silver halide-free layer (polymer 1 / gelatin) was 2 / 1, and the content of polymer 1 was 1.3 g / m 2 It was. The thickness of the silver halide-containing photosensitive layer was 2.5 μm, the mixture mass ratio of polymer 1 to gelatin in the silver halide-containing photosensitive layer (polymer 1 / gelatin) was 0.25 / 1, and the content of polymer 1 was 0.19 g / m 2 It was. The thickness of the second silver halide-free layer was 0.15 μm, the mixture mass ratio of polymer 1 to gelatin in the second silver halide-free layer (polymer 1 / gelatin) was 0.1 / 1, and the content of polymer 1 was 0.015 g / m 2 It was.

[0106] [Process B1] The photosensitive layer thus prepared was exposed to parallel light emitted from a high-pressure mercury lamp through a photomask, which corresponded to a pattern (hereinafter also referred to as the "FPC connection pattern") having a plurality of sensor electrodes 11, a plurality of lead wires 13, and a plurality of external connection terminals 14 shown in Figures 2, 4, and 5. After exposure, the obtained sample was developed with a developer described below, and further developed with a fixer (product name: N3X-R for CN16X: manufactured by Fujifilm Corporation), and then rinsed with pure water at 25°C to obtain a sample having an FPC connection pattern made of thin metal wires containing metallic silver. As shown in FIG. 2, each sample had a substrate 1 on one surface of which a plurality of sensor electrodes 11, a plurality of lead wires 13, and a plurality of external connection terminals 14 were formed. The sensor electrode 11 had a mesh pattern formed of thin metal wires as shown in Fig. 4, with the thin metal wires having a line width of 1.2 µm and each side of a rhombic unit cell (opening) constituting the mesh pattern being 600 µm long. The lead wiring 13 had a line width of 5 µm, the thin wire portions (thin metal wires 17 in Fig. 5) in the external connection terminal 14 had a line width of 2 µm, and the spacing between the thin wire portions of the thin metal wires 17 was a 20 µm square. The external connection terminal 14 had an outer shape with a width W of 150 µm and a length L of 1500 µm.

[0107] (Developer composition) The following compounds are contained in 1 liter (L) of developer: Hydroquinone 0.037 mol / L N-methylaminophenol 0.016 mol / L Sodium metaborate 0.140 mol / L Sodium hydroxide 0.360 mol / L Sodium bromide 0.031 mol / L Potassium metabisulfite 0.187 mol / L

[0108] The obtained sample was immersed in warm water at 50° C. for 180 seconds, then the water was removed with an air shower and the sample was allowed to dry naturally.

[0109] [Process C1] The sample obtained in step B1 was placed in a superheated steam treatment tank at 110°C and left to stand for 30 seconds to undergo superheated steam treatment. The steam flow rate at this time was 100 kg / h.

[0110] [Process D1] The sample obtained in step C1 was immersed in an aqueous protease solution (40°C) for 30 seconds. The sample was removed from the aqueous protease solution and washed by immersing it in warm water (liquid temperature: 50°C) for 120 seconds. The water was then removed with an air shower and the sample was allowed to air dry. The aqueous protease solution used was prepared according to the following procedure. Triethanolamine and sulfuric acid were added to an aqueous solution of a protease (Biophrase 30L, manufactured by Nagase ChemteX Corporation) (protease concentration: 0.5% by mass) to adjust the pH to 8.5.

[0111] [Process G1] The sample obtained in step D1 was placed in a superheated steam treatment tank at 110°C and left to stand for 30 seconds to undergo superheated steam treatment. The steam flow rate at this time was 100 kg / h.

[0112] [Process Q1] A protective layer-forming coating solution 1 was prepared by mixing the raw materials in the following compounding ratio. (Composition of Coating Solution 1 for Forming Protective Layer) ·CHA 40.91 parts by mass ·NPDA 56.32 parts by mass Omnirad TPO H (photopolymerization initiator) 2.77 parts by mass The surface of the sample obtained in step G1 was coated with the protective layer-forming coating solution 1 using a wire bar to form a coating film. The amount of the protective layer-forming coating solution 1 to be applied was adjusted so that the average thickness of the coating film (protective layer) after drying would be 1.5 μm. Using an ultraviolet exposure device, the coating film was irradiated with g-line rays having a wavelength of 436 nm to form a protective layer. Through the above steps, a sample of a conductive film was produced, which had a substrate, a sensor electrode having a mesh pattern, a conductive pattern including lead wires and external connection terminals, and a protective layer.

[0113] [Examples 2 and 5 to 9, Comparative Examples 1 to 3] Conductive film samples of Examples 2 and 5 to 9 and Comparative Examples 1 to 3 were each prepared according to the procedure described in Example 1, except that the type and amount of raw material monomer contained in the protective layer-forming coating liquid was changed so that the resin contained in the protective layer would be the resin listed in Table 1 below.

[0114] [Examples 3 and 4, Comparative Examples 4 and 5] Conductive film samples of Examples 3 and 4 and Comparative Examples 4 and 5 were prepared according to the procedure described in Example 2, except that the amount of the protective layer-forming coating liquid applied was changed so that the thicknesses Ta, Tb, and Tc of the protective layer were the thicknesses shown in Table 1 below.

[0115] [evaluation] [Sulfidation resistance] The sulfuration resistance of each of the conductive films produced in the examples and comparative examples was evaluated by the following method. The resistance value (R0) of the samples with the fabricated FPC connection patterns was measured. For the mesh pattern of the sensor electrode of each sample, the electrical resistance (unit: kΩ) between terminals at a distance of 4 cm was measured using an Agilent 34405A multimeter. Next, the petri dishes containing each conductive film and sulfur powder (500 g) were placed in a desiccator (internal dimensions: 310 mm × 330 mm × 420 mm), and the desiccator was then placed in a thermostatic chamber. After heating the thermostatic chamber at 70 °C for 72 hours, the resistance values ​​(R1) of the samples were measured using the method described above. The resistance change rate was calculated from the measured resistance value using the formula: Resistance change rate = (R1 / R0-1) x 100 [%]. The sulfuration resistance of each sample was evaluated from the calculated resistance change rate according to the following criteria. If the sulfuration resistance rating was A or B, it was considered to be satisfactory for practical use.

[0116] (Sulfuration resistance evaluation criteria) "A": Resistance change rate is 30% or less. "B": Resistance change rate is more than 30% and less than 50%. "C": Resistance change rate is over 50%.

[0117] [FPC connectivity] An anisotropic conductive film (ACF) CP920CM-25AC (Dexerials) and FPC were placed on the external connection terminals of the prepared samples, and the external connection terminals and FPC were bonded together via the anisotropic conductive film by performing temporary pressure bonding at 100°C for 3 seconds, followed by final pressure bonding at 130°C and 2.5 MPa for 10 seconds. After bonding, the resistance between the external output terminal on the FPC and the connection between the external connection terminal and the lead-out wiring was measured. Locations where the resistance could not be measured (overload) were determined to be connections with poor conductivity. This test was performed on 1,000 external connection terminals, and the percentage of conduction failures relative to all connections on the 1,000 sheets was calculated as the conduction failure rate. The calculated conduction failure rate was used to evaluate the FPC connectivity of each sample according to the following criteria. If the FPC connectivity rating was A or B, it was determined that the external connection terminals had excellent conductivity after thermocompression bonding with the FPC.

[0118] (FPC connectivity evaluation criteria) "A": Conduction NG rate is less than 0.1%. "B": Conduction NG rate is 0.5% or less. "C": Conduction NG rate is over 0.5%.

[0119] [result] The following table shows the composition and physical properties of the protective layer, as well as the evaluation results. In the table, the "Monomer A" column under "Resin" indicates the type of monofunctional (meth)acrylate contained in the protective layer-forming coating liquid, and the "Monomer B" column indicates the type of polyfunctional (meth)acrylate contained in the protective layer-forming coating liquid. The "Nb" column indicates the number of atoms Nb counted from the structural formula of Monomer B. The "A / B (mol %)" column indicates the ratio (mol %) of the content of monofunctional (meth)acrylate and the content (mol %) of polyfunctional (meth)acrylate relative to the total content of (meth)acrylate in the protective layer-forming coating liquid. The resin contained in the protective layer of each example was a resin having repeating units derived from monofunctional monomers and repeating units derived from polyfunctional monomers in the molar ratios shown in the "A / B" column in the table. In the table, the "Tg" column for "Protective Layer" shows the glass transition temperature Tg (°C) of the protective layer of each sample. The glass transition temperature Tg of the protective layer was determined by peeling the protective layer from each sample and measuring the peeled protective layer according to the measurement method described above. In the table, the "Ta" column under "Thickness (μm)" indicates the thickness Ta (μm) of the protective layer from the surface of the sensor electrode to the surface of the protective layer, the "Tb" column indicates the thickness Tb (μm) of the protective layer from the surface of the lead-out wiring to the surface of the protective layer, and the "Tc" column indicates the thickness Tc (μm) of the protective layer from the surface of the external connection terminal to the surface of the protective layer.

[0120] [Table 1]

[0121] As shown in Table 1, it was confirmed that the conductive film of the present invention can provide the desired effects. In contrast, the conductive film of Comparative Example 1, in which the resin contained in the protective layer did not have the repeating unit A derived from the monofunctional (meth)acrylate having a cyclic structure, had insufficient sulfurization resistance of the sensor electrode. Furthermore, the conductive film of Comparative Example 2, in which the glass transition temperature Tg of the protective layer exceeded 130°C, had insufficient FPC connectivity at the external connection terminals, and the conductive film of Comparative Example 3, in which the glass transition temperature Tg of the protective layer was less than 50°C, had insufficient sulfuration resistance of the sensor electrode. Furthermore, the conductive film of Comparative Example 4, in which the thickness Tc of the protective layer from the surface of the protective layer to the surface of the external connection terminal exceeded 3.0 μm, had insufficient FPC connectivity at the external connection terminal, and the conductive film of Comparative Example 5, in which the thickness Ta of the protective layer from the surface of the protective layer to the surface of the sensor electrode was less than 0.5 μm, had insufficient sulfuration resistance of the sensor electrode.

[0122] Comparison of Examples 1, 2 and 8 confirmed that when the repeating unit B was a repeating unit derived from a bifunctional (meth)acrylate, the sulfurization resistance was superior.

[0123] Comparison of Examples 1, 5, and 8 confirmed that the FPC connectivity was better when the repeating unit A was a repeating unit derived from a monofunctional (meth)acrylate having a monocyclic structure or a cyclic structure in which monocyclic structures are linked by a single bond. [Explanation of symbols]

[0124] 1 Base material 1a,1b surface 10,20 Conductive pattern 11,21 Sensor electrodes 12,22 Electrode connection terminal 13,23 Lead wiring 14,24 External connection terminal 15,17,MW thin metal wire 16 Opening 10 Conductive pattern 30,40 protective layer 100 Conductive Film MP Mesh Pattern R1 sensor area R2 surrounding area Ta, Tb, Tc thickness

Claims

1. A substrate; a conductive pattern including a sensor electrode made of a thin metal wire, a lead wire electrically connected to the sensor electrode, and an external connection terminal electrically connected to the lead wire, the conductive pattern being disposed on at least one surface side of the base material; a protective layer covering the entire surface of the conductive pattern, the protective layer contains a resin having a repeating unit A derived from a monofunctional (meth)acrylate having a cyclic structure and a repeating unit B derived from a polyfunctional (meth)acrylate, the protective layer has a glass transition temperature of 50 to 130°C; the thickness of the protective layer from the surface of the protective layer to the surface of the sensor electrode is 0.5 μm or more; A conductive film, wherein the thickness of the protective layer from the surface of the protective layer to the surface of the external connection terminal is 3.0 μm or less.

2. The conductive film according to claim 1 , wherein the polyfunctional (meth)acrylate is a difunctional (meth)acrylate.

3. 3. The conductive film according to claim 2, wherein, in a linking structure linking two (meth)acryloyl groups possessed by the bifunctional (meth)acrylate, when a path is imagined that starts from an oxygen atom linked to one of the two (meth)acryloyl groups and ends at an oxygen atom linked to the other of the two (meth)acryloyl groups, and traces the atoms and interatomic bonds included in the linking structure so as to minimize the number of atoms, the number Nb of atoms included in the path including the oxygen atom at the starting point and the oxygen atom at the ending point is 5 to 11.

4. The conductive film according to any one of claims 1 to 3, wherein the monofunctional (meth)acrylate has 9 to 17 carbon atoms.

5. 4. The conductive film according to claim 1, wherein the cyclic structure is a monocyclic structure or a structure in which monocyclic structures are linked by a single bond.

6. The conductive film according to any one of claims 1 to 3, wherein the monofunctional (meth)acrylate comprises at least one selected from the group consisting of cyclohexyl acrylate and 2-(2-biphenylyloxy)ethyl acrylate.

7. A touch panel comprising the conductive film according to any one of claims 1 to 3.

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