JP7314573B2 - Method for manufacturing conductive film, conductive film, sensor, touch panel, and image display device - Google Patents

Description

The present invention relates to a method for producing a conductive film, a conductive film, a sensor, a touch panel, and an image display device.

2. Description of the Related Art In recent years, image display devices such as smartphones and tablet terminals are sometimes provided with a touch panel that enables direct input of information by touching the image display surface with a finger or the like.

A touch panel usually includes a conductive film having conductive portions on a light-transmitting substrate. Indium tin oxide (ITO) is mainly used as the conductive material of the conductive portion in the light-transmissive conductive film. However, since ITO does not have flexibility, when a flexible base material is used as the light-transmissive base material, cracks are likely to occur in the conductive portion.

For this reason, currently, instead of ITO, use of metal nanowires with a nano-sized fiber diameter as a conductive material forming the conductive portion is under study.

Usually, a die coating method or a bar coating method is used for applying a metal nanowire dispersion liquid in forming a conductive portion (see Patent Document 1). It is also known to use an inkjet method or screen printing to apply a metal nanowire dispersion (see Patent Documents 2 and 3).

JP 2018-169962 A JP 2015-45006 A JP 2016-121241 A

When forming a linear conductive portion such as wiring, a desired low line resistance value is required. Here, if the content of metal nanowires in the conductive part is increased, the wire resistance value tends to decrease, so it is conceivable to increase the content of metal nanowires in order to achieve the desired wire resistance value. However, increasing the content of metal nanowires increases the cost because metal nanowires are expensive. For this reason, the current situation is that a conductive film that achieves a desired line resistance value while achieving cost reduction has not yet been obtained.

The present invention has been made to solve the above problems. In other words, it is an object of the present invention to provide a method for manufacturing a conductive film that achieves a desired line resistance value while reducing costs. Another object of the present invention is to provide a conductive film capable of realizing a desired line resistance value while reducing costs, and a sensor, a touch panel, and an image display device having this conductive film.

The present invention includes the following inventions.
[1] A method for producing a conductive film comprising a light-transmitting substrate and a patterned conductive portion provided on the first surface side of the light-transmitting substrate, wherein the discharging portion of a contact dispenser is discharged from the discharging portion to the first surface side of the light-transmitting substrate while moving the discharging portion relative to the light-transmitting substrate to apply the conductive fiber dispersion linearly.

[2] The method for producing a conductive film according to [1] above, wherein the relative movement speed of the ejection part with respect to the light-transmitting substrate is 5 mm/sec or more and 500 mm/sec or less when the conductive fiber dispersion is discharged.

[3] A conductive film comprising a light-transmitting substrate and a patterned conductive portion provided on the first surface side of the light-transmitting substrate, wherein the conductive portion includes a plurality of conductive fibers and is linearly formed, and the conductive fibers in the conductive portion are arranged along the direction in which the conductive portion extends.

[4] The conductive film according to [5] above, wherein the conductive portion has a line width of 100 μm or more and 4000 μm or less.

[5] A sensor comprising the conductive film according to [3] or [4] above.

[6] A touch panel comprising the conductive film according to [3] or [4] above.

[7] An image display device comprising a display element, and the conductive film according to [3] or [4] or the touch panel according to [6], which is arranged closer to the viewer than the display element.

[8] The image display device according to [7] above, wherein the display element is an organic light-emitting diode element.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electroconductive film which can aim at reduction of cost can be provided, realizing a desired line resistance value. Further, according to the present invention, it is possible to provide a conductive film capable of realizing a desired line resistance value while reducing costs, and a sensor, a touch panel, and an image display device provided with this conductive film.

FIG. 1 is a schematic configuration diagram of a conductive film according to an embodiment. 2 is a plan view of a portion of the conductive film shown in FIG. 1; FIG. 3 is an enlarged plan view of a portion of the conductive film of FIG. 2. FIG. FIG. 4 is a schematic configuration diagram of another conductive film according to the embodiment. 5 is a plan view of a portion of the conductive film shown in FIG. 4; FIG. 6 is an enlarged plan view of a portion of the conductive film of FIG. 5. FIG. 7(A) and 7(B) are diagrams schematically showing the manufacturing process of the conductive film according to the embodiment. 8A and 8B are diagrams schematically showing the manufacturing process of the conductive film according to the embodiment. FIG. 9 is a schematic configuration diagram of an image display device according to the embodiment.

A conductive film, a sensor, a touch panel, and an image display device according to embodiments of the present invention will be described below with reference to the drawings. As used herein, "optical transparency" means the property of transmitting light. Also, the term “light transmissive” does not necessarily mean transparent, and may be translucent. FIG. 1 is a schematic configuration diagram of a conductive film according to the present embodiment, FIG. 2 is a plan view of a portion of the conductive film shown in FIG. 1, and FIG. 3 is an enlarged plan view of a portion of the conductive film of FIG. 4 is a schematic configuration diagram of another conductive film according to the embodiment, FIG. 5 is a plan view of part of the conductive film shown in FIG. 4, and FIG. 6 is an enlarged plan view of part of the conductive film of FIG. 7 and 8 are diagrams schematically showing the manufacturing process of the conductive film according to the embodiment.

<<<Conductive film>>>
The conductive film 10 shown in FIG. 1 includes a light-transmitting substrate 11, a conductive portion 12 provided on the first surface 11A side of the light-transmitting substrate 11, and a light-transmitting functional layer 13 provided on the second surface 11B side opposite to the first surface 11A of the light-transmitting substrate 11. However, the conductive film 10 only needs to include the light-transmitting substrate 11 and the conductive portion 12, and does not need to include the light-transmitting functional layer 13. The light-transmitting functional layer 13 is provided on the second surface 11B side of the light-transmitting substrate 11, but may be provided between the light-transmitting substrate 11 and the conductive portion 12, or may be provided on both the second surface 11B side and between the light-transmitting substrate 11 and the conductive portion 12. In the conductive film 10 shown in FIG. 1, the conductive portions 12 are provided only on one side, but the conductive portions may be provided on both sides of the conductive film.

The conductive portion 12 shown in FIG. 1 is in a linear state after patterning. A surface 10A of the conductive film 10 is composed of a surface 12A of the conductive portion 12 . In this specification, the surface of the conductive film is used to mean one surface of the conductive film, so the surface opposite to the surface of the conductive film is referred to as the back surface to distinguish it from the surface of the conductive film. A back surface 10B of the conductive film 10 serves as a front surface 13A of the light transmissive functional layer 13 .

The haze value (total haze value) of the conductive film 10 is preferably 5% or less. If the haze value of the conductive film 10 is 5% or less, sufficient optical performance can be obtained. The haze value can be measured using a haze meter (for example, product name "HM-150", manufactured by Murakami Color Research Laboratory) in accordance with JIS K7136:2000 under an environment of temperature 23±5° C. and relative humidity 30% to 70%. The haze value is a value when the entire conductive film is measured, and after cutting it into a size of 50 mm × 100 mm, the conductive part side is the non-light source side (not limited to the case where the conductive part is formed on both sides) and the conductive part extends horizontally. In this specification, "measure three times" means not measuring the same place three times or more, but measuring three or more different places. The conductive film 10 has a flat surface 10A when viewed visually, and the laminated layers such as the conductive part 12 are also flat, and the variation in film thickness is within ± 10% of the average value of the thickness. Therefore, it is considered that by measuring the haze value at three or more different points of the cut-out conductive film, an approximate average value of the haze values of the entire in-plane of the conductive film can be obtained. As for the number of measurements, it is preferable to measure five times, that is, to measure at five different points, and it is preferable to obtain an average value from the measured values at three points, excluding the maximum and minimum values. If the conductive film cannot be cut into the above size, for example, the HM-150 has an inlet opening of 20 mmφ for measurement, so a sample with a diameter of 21 mm or more is required. Therefore, the conductive film may be appropriately cut into a size of 22 mm×22 mm or more. When the size of the conductive film is small, the measurement points are set to three by gradually shifting or changing the angle within the range where the light source spot does not deviate. More preferably, the haze value of the conductive film 10 is 3% or less, 2% or less, 1.5% or less, 1.2% or less, or 1.1% or less. The variation in the obtained haze value is within ±10% even if the measurement object is as long as 1 m × 3000 m or as large as a 5-inch smartphone, and if it falls within the above preferable range, low haze and low resistance value are more likely to be obtained. In addition, it is preferable that the haze value is the same as the above even in the entire laminated body in which a plurality of layers are stacked, such as a touch panel sensor on which a conductive film is mounted.

The total light transmittance of the conductive film 10 is preferably 80% or more. If the total light transmittance of the conductive film 10 is 80% or more, sufficient optical performance can be obtained. The total light transmittance can be measured using a haze meter (for example, product name "HM-150", manufactured by Murakami Color Research Laboratory) in accordance with JIS K7361-1: 1997 under an environment of temperature 23 ± 5 ° C. and relative humidity 30% or more and 70% or less. More preferably, the total light transmittance of the conductive film 10 is 85% or higher, 88% or higher, or 89% or higher. The total light transmittance is measured at 5 points, and the average value of the measured values at 3 points excluding the maximum and minimum values.

When another film is provided on the conductive film via an adhesive layer or adhesive layer, the haze value and total light transmittance are measured after peeling off the other film along with the adhesive layer or adhesive layer, and a folding test shall be performed. Peeling of other films can be performed, for example, as follows. First, a laminate consisting of a conductive film and another film attached via an adhesive layer or adhesive layer is heated with a dryer, and then the edge of a cutter is inserted into the interface between the conductive film and the other film to slowly peel it off. By repeating such heating and peeling, the adhesive layer, adhesive layer, and other films can be peeled off. It should be noted that even if such a peeling step exists, it does not significantly affect the measurement of the haze value and the like and the folding test.

In addition, as described above, when measuring the haze value and total light transmittance of the conductive film 10, or when performing a folding test on the conductive film 10, it is necessary to cut the conductive film 10 into the above-mentioned sizes. shall be cut to the size of In addition, when the conductive film 10 is in a roll shape, a predetermined length is fed out from the roll of the conductive film 10, and the effective region near the center where the quality is stable is cut out instead of the non-effective region including both ends extending along the longitudinal direction of the roll. In addition, when measuring the haze value and total light transmittance of the conductive film 10 or when performing a folding test on the conductive film 10, the measurement is performed using the above device, but it may be measured by a similar device such as a successor model.

The thickness of the conductive film 10 is not particularly limited, but may be 500 μm or less. The lower limit of the thickness of the conductive film 10 is more preferably 5 μm or more, 10 μm or more, or 20 μm or more from the viewpoint of handleability. The upper limit of the thickness of the conductive film 10 is preferably 250 μm or less, 100 μm or less from the viewpoint of thinning, and more preferably 78 μm or less, particularly 45 μm or less when flexibility is emphasized. Therefore, when importance is placed on flexibility, the thickness of the conductive film 10 is preferably 5 μm or more and 78 μm or less, more preferably 28 μm or less and 20 μm or less. The thickness of the conductive film is obtained by randomly measuring ten thicknesses from a cross-sectional photograph of the conductive film taken using a transmission electron microscope (TEM), a scanning transmission electron microscope (STEM), or a scanning electron microscope (SEM). A conductive film generally has thickness unevenness. In the present invention, since the conductive film is used for optical purposes, the thickness unevenness is preferably ±2 μm or less, more preferably ±1 μm or less of the average thickness.

When the thickness of the conductive film is measured using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM), it can be measured by the same method as the method for measuring the film thickness of the conductive portion. However, the magnification when taking a cross-sectional photograph of the conductive film is 100 to 20,000 times. When measuring the thickness of the conductive film using a scanning electron microscope (SEM), the cross section of the conductive film may be obtained using an ultramicrotome (product name “Ultramicrotome EM UC7”, manufactured by Leica Microsystems) or the like. A sample to be measured with a TEM or STEM is prepared as an ultra-thin slice using the above-mentioned ultramicrotome, with a feed-out thickness of 100 nm. The produced ultra-thin section is collected with a mesh (150) with a collodion membrane, and used as a measurement sample. At the time of cutting with an ultramicrotome, pretreatment such as embedding a measurement sample in resin may be performed to facilitate cutting.

The use of the conductive film 10 is not particularly limited, and for example, it may be used in various uses (for example, sensor use) in which a transparent conductive film is used. In addition, the conductive film of the present invention is suitable for image display devices (including smartphones, tablet terminals, wearable terminals, personal computers, televisions, digital signage, public information displays (PID), in-vehicle displays, etc.) and in-vehicle (including all vehicles such as trains and vehicle construction machines). When the conductive film is used as a vehicle-mounted sensor, for example, it may be a sensor placed in a portion touched by a person, such as a steering wheel or a seat. In addition, the conductive film is also preferable for applications requiring flexibility such as foldability and rollability. It may also be used for electrical appliances and windows used in homes and vehicles (including all types of vehicles such as trains and vehicle construction machinery). In particular, the conductive film of the present invention can be suitably used in areas where transparency is emphasized. In addition, the conductive film of the present invention can be suitably used not only for technical aspects such as transparency, but also for electrical appliances that require good design. Specific applications of the conductive film other than image display devices include, for example, defrosters, antennas, solar cells, audio systems, speakers, fans, electronic blackboards, and carrier films for semiconductors. The shape of the conductive film in use is appropriately designed according to the application, and is not particularly limited, but may be curved, for example.

The conductive film 10 may be cut into a desired size, or may be in the form of a roll. When the conductive film is in roll form, it may be cut to a desired size at this stage, or may be cut to a desired size after, for example, post-processing. When the conductive film 10 is cut to a desired size, the size of the conductive film is not particularly limited and is appropriately determined according to the size of the display surface of the image display device. Specifically, the size of the conductive film may be, for example, 5 inches or more and 500 inches or less. As used herein, "inch" means the length of the diagonal when the conductive film is square, the diameter when it is circular, and the average value of the sum of the short diameter and long diameter when it is elliptical. Here, when the conductive film has a square shape, the aspect ratio of the conductive film when calculating the above inch is not particularly limited as long as there is no problem with the display screen of the image display device. For example, height:width=1:1, 4:3, 16:10, 16:9, 2:1, and the like. However, particularly in in-vehicle applications and digital signage, which are rich in design, the aspect ratio is not limited to such an aspect ratio. In addition, when the size of the conductive film 10 is large, it is cut out from an arbitrary position to an appropriately manageable size such as A4 size (210 mm × 297 mm) or A5 size (148 mm × 210 mm), and then cut out to the size of each measurement item. In addition, for example, when the conductive film 10 is in a roll shape, a predetermined length is fed out from the roll of the conductive film 10, and the desired size is cut out from the effective region near the center where the quality is stable, rather than the non-effective region including both ends extending along the longitudinal direction of the roll.

<<Light transmissive substrate>>
The light-transmitting base material 11 is not particularly limited as long as it has light-transmitting properties. For example, the constituent material of the light-transmitting base material 11 includes a base material containing a resin having light-transmitting properties. Such resins are not particularly limited as long as they have optical transparency. Examples thereof include polyolefin-based resins, polycarbonate-based resins, polyacrylate-based resins, polyester-based resins, aromatic polyetherketone-based resins, polyethersulfone-based resins, polyimide-based resins, polyamide-based resins, polyamideimide-based resins, or mixtures of two or more of these resins. Light-transmitting substrates are easily scratched because they come into contact with a coating device when coating a light-transmitting functional layer or the like, but a light-transmitting substrate made of a polyester-based resin is less likely to be scratched even when it comes into contact with a coating device.

When obtaining a foldable conductive film as the conductive film, it is preferable to use a polyimide resin, a polyamideimide resin, a polyamide resin, a polyester resin, or a mixture thereof, since the resin constituting the light-transmitting substrate has good flexibility. In addition, among these, not only has excellent flexibility, but also has excellent hardness and transparency, is also excellent in heat resistance, and can be baked to impart even more excellent hardness and transparency. From the viewpoint, polyimide resins, polyamide resins, or mixtures thereof are preferable.

Examples of polyolefin-based resins include resins containing at least one of polyethylene, polypropylene, cycloolefin polymer-based resins, and the like as a constituent. Examples of cycloolefin polymer resins include those having a norbornene skeleton.

Examples of polycarbonate-based resins include aromatic polycarbonate resins based on bisphenols (such as bisphenol A) and aliphatic polycarbonate resins such as diethylene glycol bisallyl carbonate.

Examples of polyacrylate-based resins include polymethyl (meth)acrylate base material, polyethyl (meth)acrylate base material, methyl (meth)acrylate-butyl (meth)acrylate copolymer, and the like.

Examples of polyester-based resins include resins containing at least one of polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN) as a constituent component.

Examples of aromatic polyetherketone-based resins include polyetheretherketone (PEEK).

The polyimide resin may partially contain a polyamide structure. Polyamide structures that may be included include, for example, polyamideimide structures containing tricarboxylic acid residues such as trimellitic anhydride, and polyamide structures containing dicarboxylic acid residues such as terephthalic acid. Polyamide-based resin is a concept that includes not only aliphatic polyamides but also aromatic polyamides (aramids). Specifically, examples of polyimide-based resins include compounds having structures represented by the following chemical formulas (1) and (2). In the following chemical formula, n is a repeating unit and represents an integer of 2 or more. Among the compounds represented by the following chemical formulas (1) and (2), the compound represented by the chemical formula (1) is preferable because of its low retardation and high transparency.

The thickness of the light-transmissive substrate 11 is not particularly limited, but it can be 500 μm or less, and the lower limit of the thickness of the light-transmissive substrate 11 is more preferably 3 μm or more, 5 μm or more, 10 μm or more, or 20 μm or more from the viewpoint of handling properties. The upper limit of the thickness of the light-transmitting substrate 11 is preferably 250 μm or less, 100 μm or less, 80 μm or less, or 50 μm or less from the viewpoint of thinning, and more preferably 35 μm or less, particularly 18 μm or less when flexibility is emphasized. The thickness of the light-transmitting substrate is obtained by randomly measuring ten thicknesses from a cross-sectional photograph of the light-transmitting substrate taken using a transmission electron microscope (TEM), a scanning transmission electron microscope (STEM), or a scanning electron microscope (SEM). A light-transmitting substrate generally has thickness unevenness. In the present invention, since the light-transmitting base material is used for optical purposes, the thickness unevenness is preferably ±2 μm or less, more preferably ±1 μm or less of the average thickness.

When measuring the thickness of the light-transmitting substrate using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM), it can be measured by the same method as the method for measuring the film thickness of the conductive portion. However, the magnification when taking a cross-sectional photograph of the light-transmitting substrate is 100 to 20,000 times. When measuring the thickness of the light-transmitting substrate using a scanning electron microscope (SEM), the cross-section of the light-transmitting substrate may be obtained using an ultramicrotome (product name "Ultramicrotome EM UC7", manufactured by Leica Microsystems) or the like. For TEM and STEM measurement samples, an ultra-thin section is prepared using the above-mentioned ultramicrotome, setting the feed-out thickness to 100 nm. The produced ultra-thin section is collected with a mesh (150) with a collodion membrane, and used as a measurement sample for TEM or STEM. When cutting with an ultramicrotome, the sample may be subjected to pretreatment such as embedding in resin to facilitate cutting.

Conductive fibers such as silver nanowires themselves are suitable for flexibility, for example, but if the thickness of the light-transmitting base material or functional layer (excluding the conductive part) for laminating the conductive part containing the conductive fiber is large, cracks may occur in the light-transmitting base material or the functional layer at the bent portion during folding, and the cracks may cause disconnection of the conductive fibers. In addition to the failure to obtain the desired resistance value due to the disconnection described above, there is a risk that poor appearance, specifically, white turbidity and poor adhesion due to cracks, may occur. Therefore, when a conductive film is used for flexible applications, it is important to control the thickness of the light-transmitting base material and functional layers and the adhesion between each layer (adhesion due to chemical bonding affected by materials and physical adhesion such that cracks do not occur). In particular, when the light-transmissive base material 11 contains a polyester-based resin or a polyimide-based resin, it is important to control the thickness of the light-transmissive base material because the resistance to cracking varies depending on the thickness.

For example, when the light-transmitting base material 11 contains a polyester-based resin, the thickness of the light-transmitting base material 11 is preferably 45 μm or less. If the thickness of the light-transmitting base material 11 is 45 μm or less, cracking of the light-transmitting base material 11 at the bent portion during folding can be suppressed, and cloudiness at the bent portion can be suppressed. In this case, the upper limit of the thickness of the light-transmitting substrate 11 is preferably 35 μm or less, 29 μm or less, and particularly 18 μm or less. In this case, the lower limit of the thickness of the light-transmitting base material 11 is preferably 5 μm or more from the viewpoint of handleability and the like.

When the light-transmitting substrate 11 contains, for example, a polyimide-based resin, a polyamide-based resin, a polyamide-imide-based resin, or a mixture thereof, the light-transmitting substrate 11 is preferably thin from the viewpoint of suppression of cracking of the light-transmitting substrate 11 when folded, optical properties, and mechanical properties, and specifically, is preferably 75 μm or less. In this case, the upper limit of the thickness of the light-transmitting substrate 11 is preferably 70 μm or less, 50 μm or less, 35 μm or less, 29 μm or less, and particularly preferably 20 μm or less and 18 μm or less. In this case, the lower limit of the thickness of the light-transmitting base material 11 is preferably 5 μm or more from the viewpoint of handleability and the like.

When the thickness of each light-transmitting base material is 35 μm or less, particularly when it is 5 μm or more and 20 μm or less or 18 μm or less, it is preferable to apply a protective film during production, because the workability is improved.

The light-transmitting base material 11 may be subjected to a physical treatment such as corona discharge treatment, oxidation treatment, etc. on the surface in order to improve adhesiveness. In addition, the light-transmitting substrate 11 may have, on at least one side thereof, a base layer for improving adhesion with other layers, preventing sticking during winding, and/or suppressing repelling of the coating liquid forming the other layers. However, if a conductive fiber-containing composition containing conductive fibers and a dispersion medium is used to form a conductive portion on the surface of the base layer, the dispersion medium permeates the base layer, and the conductive fibers may also enter the base layer, which may increase the electrical resistance value, although the degree varies depending on the type of dispersion system. In the present specification, the underlying layer present on at least one side of the light-transmitting substrate and in contact with the light-transmitting substrate constitutes part of the light-transmitting substrate and is not included in the light-transmitting functional layer.

The base layer is a layer having a function of improving adhesion with other layers, a function of preventing sticking during winding, and/or a function of suppressing repelling of the coating liquid forming other layers. Whether or not the light-transmitting substrate has an underlayer can be confirmed by observing the cross section around the interface between the light-transmitting substrate and the conductive part and between the light-transmitting substrate and the light-transmitting functional layer at a magnification of 1,000 to 500,000 (preferably 25,000 to 50,000) using a scanning electron microscope (SEM), scanning transmission electron microscope (STEM), or transmission electron microscope (TEM). In addition, since the base layer may contain particles such as a lubricant to prevent sticking during winding, it can be determined that this layer is the base layer by the presence of particles between the light-transmitting base material and the light-transmitting functional layer.

The film thickness of the underlayer is preferably 10 nm or more and 1 μm or less. If the film thickness of the underlayer is 10 nm or more, the function as the underlayer can be sufficiently exhibited, and if the film thickness of the underlayer is 1 μm or less, there is no fear of optically affecting it. The film thickness of the underlayer is taken at 1,000 to 500,000 times (preferably 25,000 to 50,000 times) using a scanning electron microscope (SEM), a scanning transmission electron microscope (STEM), or a transmission electron microscope (TEM). The thickness of the underlayer is measured at 10 locations randomly from a cross-sectional photograph taken, and the arithmetic mean value of the thicknesses at 10 locations is taken. The lower limit of the film thickness of the underlayer is more preferably 30 nm or more, and the upper limit is more preferably 150 nm or less. The film thickness of the underlying layer can also be measured by the same method as for the film thickness of the conductive portion 12 . When taking a cross-sectional photograph by SEM, TEM, or STEM, it is preferable to prepare a measurement sample using an ultramicrotome as described above.

The underlayer contains, for example, an anchor agent and a primer agent. Examples of anchor agents and primer agents include polyurethane resins, polyester resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate copolymers, acrylic resins, polyvinyl alcohol resins, polyvinyl acetal resins, copolymers of ethylene and vinyl acetate or acrylic acid, copolymers of ethylene and styrene and/or butadiene, thermoplastic resins such as olefin resins and/or modified resins thereof, polymers of ionizing radiation polymerizable compounds, and polymers of thermally polymerizable compounds. It is possible to use at least one of

The base layer may contain particles such as a lubricant to prevent sticking during winding as described above. Examples of the particles include silica particles.

<<Light transmissive functional layer>>
The light transmissive functional layer 13 is provided on the second surface 11B side of the light transmissive substrate 11 . The "light-transmitting functional layer" as used herein is a layer intended to have light-transmitting properties and to exhibit some function in the conductive film. Specifically, the light-transmitting functional layer includes, for example, a layer for exerting a hard coat function, a refractive index adjusting function, and/or a color adjusting function. The light-transmitting functional layer may be not only a single layer but also a laminate of two or more layers. When the light-transmitting functional layer is a laminate of two or more layers, each layer may have the same function or may have different functions. In the present embodiment, the case where the light-transmissive functional layer 13 is a layer exhibiting a hard coat function, that is, a hard coat layer will be described. In order to obtain flexibility, the light-transmissive functional layer may be a layer other than the hard coat layer. In that case, the light-transmitting functional layer may have a pencil hardness or cross-sectional hardness less than those shown below. Even in such a case, the mechanical orientation strength is higher than that of the light-transmitting substrate alone, so it functions as a hard coat layer.

The light-transmitting functional layer 13 is a layer having a hardness of "H" or higher in a pencil hardness test (4.9N load) defined by JIS K5600-5-4:1999. By setting the pencil hardness to "H" or more, the conductive film 10 becomes hard and durability can be improved. From the viewpoint of toughness of the light-transmissive functional layer and prevention of curling, the upper limit of the pencil hardness of the surface 10A of the conductive film 10 is preferably about 2H to 4H.

The indentation hardness (H _IT ) of the light transmissive functional layer 13 is preferably 100 MPa or more. If flexibility is of utmost importance, it is preferably between 20 and less than 100 MPa. The lower limit of the indentation hardness of the light transmissive functional layer 13 may be 200 MPa or higher or 300 MPa or higher, and the upper limit may be 800 MPa or lower from the viewpoint of preventing microcracks and maintaining the adhesion at the interface between the light transmissive functional layer, the light transmissive substrate, and the conductive portion. By setting such a lower limit and an upper limit, it is possible to maintain the flexibility of the conductive portion itself due to the conductive fiber or the like. In addition, in a structure having a conductive portion, it is required for practical use that the resistance value, physical properties, and optical properties after the folding test are substantially the same as before the test. In addition, the light-transmitting functional layer is effective as a layer that plays a role of preventing scratches during processing. For this reason, in order to obtain the physical properties for practical use as described above while taking advantage of the flexibility of the conductive fibers such as silver nanowires, it is preferable to be within the above numerical range. Although it depends on the application, a configuration in which the light-transmitting functional layer is provided on both sides of the light-transmitting substrate is preferable to the case where the light-transmitting functional layer is provided only on one side of the light-transmitting substrate.

The term "indentation hardness" used herein is a value obtained from a load-displacement curve from loading to unloading of the indenter. The above indentation hardness (H _IT ) is measured using a Bruker TI950 TriboIndenter for a measurement sample under an environment of temperature 23±5° C. and relative humidity 30% or more and 70% or less. A measurement sample may be produced by the same method as the sample produced when taking a cross-sectional photograph by the above-described SEM. When the film thickness of the light-transmitting functional layer 13 is thin, it is preferable to sufficiently increase the measurement area using an oblique cutting device such as a surface and interfacial cutting analysis system (SAICAS). Cross-sectional analysis is usually performed by cutting a sample perpendicular to the surface (perpendicular cross-section). However, when the layer thickness of each layer of a multi-layered sample is thin and a wide analysis area is required, it is difficult to selectively analyze a specific layer. However, when the cross section is prepared by oblique cutting, the sample surface can be exposed more widely than when the vertical cross section is used. For example, if a slope of 10° is made with respect to the horizontal plane, the sample surface becomes slightly wider than the vertical section by a little less than 6 times. For this reason, it is possible to analyze a sample that is difficult to analyze with a vertical section by preparing a section by oblique cutting with SAICAS. Next, in the cross section of the obtained measurement sample, a flat portion is searched, and in this flat portion, a Berkovich indenter (triangular pyramid, TI-0039 manufactured by Bruker) is pressed vertically into the light-transmitting functional layer 13 at a speed of 10 nm/sec so that the maximum indentation displacement is 100 nm in measurement based on displacement, while applying a load from a displacement of 0 nm to a displacement of 100 nm in 10 seconds. Here, in order to avoid the influence of the light-transmitting substrate and the side edges of the light-transmitting functional layer, the Berkovich indenter is pushed into a portion of the light-transmitting functional layer that is 500 nm away from the interface between the light-transmitting substrate and the light-transmitting functional layer toward the center of the light-transmitting functional layer and 500 nm or more away from both side ends of the light-transmitting functional layer toward the center of the light transmitting functional layer. After holding the displacement of 100 nm for 5 seconds, the load is removed from the displacement of 100 nm to 0 nm in 10 seconds. Then, the indentation depth h (nm) corresponding to the indentation load F (N) at this time is continuously measured to create a load-displacement curve. From the created load-displacement curve, the indentation hardness is obtained by dividing the maximum indentation load F _max (N) by the contact projected area A _p (mm ² ) where the indenter and the light-transmissive functional layer 13 are in contact, as in the following formula (1). The indentation hardness is the arithmetic mean value of eight measurement values obtained by subtracting the maximum value and minimum value from ten measurement values. A _p is the projected contact area corrected for the tip curvature of the indenter by the Oliver-Pharr method using fused quartz as a standard sample.
_HIT = _Fmax / _Ap (1)

In order to control the physical properties of a conductive film having a light-transmitting functional layer, it is conceivable to measure the elastic modulus of the light-transmitting functional layer itself, but the light-transmitting functional layer having a three-dimensional crosslinked structure is thin and fragile. For this reason, in the above, evaluation is performed by hardness measurement by the nanoindentation method. By this method, it is possible to measure the physical properties of the film itself, even if it is a thin polymer material, regardless of the influence of the light-transmitting substrate, and the hardness can be analyzed from the load-displacement curve of the elastic/plastically deformable material by Equation (1) as described above.

The film thickness of the light-transmitting functional layer 13 is preferably 0.2 μm or more and 15 μm or less. If the film thickness of the light-transmitting functional layer 13 is 0.2 μm or more, desired hardness can be obtained, and if the film thickness of the light-transmitting functional layer 13 is 15 μm or less, the thickness of the conductive film 10 can be reduced. From the viewpoint of hard coating properties, the lower limit of the film thickness of the light-transmitting functional layer 13 is more preferably 0.3 μm or more, 0.5 μm or more, or 0.7 μm or more. Further, the upper limit of the film thickness of the light transmissive functional layer 13 is more preferably 12 μm or less, 10 μm or less, 7 μm or less, 5 μm or less, or 2 μm or less from the viewpoint of thinning the light transmissive functional layer 13 . However, when the light-transmitting functional layers are laminated on both sides of the light-transmitting substrate, the film thickness is preferably thinner than that of the light-transmitting functional layer 13 described above. In this case, in order to reduce the thickness and obtain good flexibility, the film thickness of each light-transmitting functional layer is preferably 3 μm or less, 1.5 μm or less, or 1 μm or less. As will be described later, the line thickness of the conductive portion 12 is preferably less than 300 nm, but when the conductive portion is laminated on the light transmissive functional layer, the conductive portion may be mixed in the light transmissive functional layer. In such cases, the interface between the functional layer and the conductive portion may not be discernible. In this case, the preferred film thickness of the light transmissive functional layer may be the total thickness of the light transmissive functional layer and the conductive portion.

The thickness of the light-transmitting functional layer is obtained by randomly measuring the thickness at 10 points from a cross-sectional photograph of the light-transmitting functional layer taken with a transmission electron microscope (TEM), scanning transmission electron microscope (STEM), or scanning electron microscope (SEM), and excluding the maximum and minimum values from the 10 thicknesses measured, and averaging the thickness at 8 points. The light transmissive functional layer generally has thickness unevenness. In the present invention, since the light-transmitting functional layer is used for optical purposes, the thickness unevenness is preferably ±10% or less of the average thickness value, more preferably ±5% or less of the average thickness value.

When measuring the thickness of the light-transmitting substrate using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM), it can be measured by the same method as the method for measuring the film thickness of the conductive portion. However, the magnification when taking a cross-sectional photograph of the light-transmitting substrate is 100 to 20,000 times. When measuring the thickness of the light-transmitting substrate using a scanning electron microscope (SEM), the cross-section of the light-transmitting substrate may be obtained using an ultramicrotome (product name "Ultramicrotome EM UC7", manufactured by Leica Microsystems) or the like. For TEM and STEM measurement samples, an ultra-thin section is prepared using the above-mentioned ultramicrotome, setting the feed-out thickness to 100 nm. The produced ultra-thin section is collected with a mesh (150) with a collodion membrane, and used as a measurement sample for TEM or STEM. At the time of cutting with an ultramicrotome, pretreatment such as embedding a measurement sample in resin may be performed to facilitate cutting.

If the thickness of the light-transmitting substrate 11 is thin, it becomes difficult to pass through the line, it becomes easy to avoid, and it becomes difficult to handle in the process such as being easily damaged. When the conductive film 10 is used for flexible applications, it is important that the light-transmitting functional layer 13 adheres to the light-transmitting substrate 11 and follows the light-transmitting substrate 11 when folded. In order to form the light-transmitting functional layer 13 that adheres to the light-transmitting substrate 11 and can follow the light-transmitting substrate 11 when folded, the balance of the thickness of the light-transmitting functional layer 13 with respect to the thickness of the light-transmitting substrate 11 is also important.

The light transmissive functional layer 13 can be composed of at least a light transmissive resin. In addition to the light-transmitting resin, the light-transmitting functional layer 13 may contain inorganic particles, organic particles, and a leveling agent.

<Light transmissive resin>
Examples of the light-transmissive resin in the light-transmissive functional layer 13 include those containing a polymer (cured product, crosslinked product) of a polymerizable compound. The light-transmitting resin may contain a solvent-drying type resin in addition to the polymer of the polymerizable compound. Polymerizable compounds include ionizing radiation polymerizable compounds and/or thermally polymerizable compounds. Among these, the ionizing radiation-polymerizable compound is preferable as the polymerizable compound because it has a high curing speed and is easy to design.

The ionizing radiation polymerizable compound has at least one ionizing radiation polymerizable functional group in one molecule. The term "ionizing radiation-polymerizable functional group" as used herein is a functional group capable of undergoing a polymerization reaction upon exposure to ionizing radiation. Examples of ionizing radiation-polymerizable functional groups include ethylenically unsaturated groups such as (meth)acryloyl groups, vinyl groups, and allyl groups. In addition, "(meth)acryloyl group" is meant to include both "acryloyl group" and "methacryloyl group". Moreover, visible light, ultraviolet rays, X-rays, electron beams, α-rays, β-rays, and γ-rays are examples of the ionizing radiation irradiated when polymerizing the ionizing radiation-polymerizable compound.

Examples of the ionizing radiation-polymerizable compound include ionizing radiation-polymerizable monomers, ionizing radiation-polymerizable oligomers, and ionizing radiation-polymerizable prepolymers, and these can be appropriately adjusted and used. As the ionizing radiation-polymerizable compound, a combination of an ionizing radiation-polymerizable monomer and an ionizing radiation-polymerizable oligomer or ionizing radiation-polymerizable prepolymer is preferable.

Examples of the ionizing radiation-polymerizable monomer include monomers containing a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; (Meth)acrylic esters such as tall di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and glycerol (meth)acrylate.

As the ionizing radiation-polymerizable oligomer, a polyfunctional oligomer having two or more functional groups is preferable, and a polyfunctional oligomer having three (trifunctional) or more ionizing radiation-polymerizable functional groups is preferable. Examples of the polyfunctional oligomer include polyester (meth)acrylate, urethane (meth)acrylate, polyester-urethane (meth)acrylate, polyether (meth)acrylate, polyol (meth)acrylate, melamine (meth)acrylate, isocyanurate (meth)acrylate, epoxy (meth)acrylate, and the like.

The ionizing radiation polymerizable prepolymer has a weight average molecular weight of more than 10,000, preferably 10,000 or more and 80,000 or less, more preferably 10,000 or more and 40,000 or less. When the weight-average molecular weight exceeds 80,000, the viscosity is high, so that the coatability is lowered, and the appearance of the obtained light-transmitting resin may be deteriorated. Polyfunctional prepolymers include urethane (meth)acrylate, isocyanurate (meth)acrylate, polyester-urethane (meth)acrylate, epoxy (meth)acrylate and the like.

A thermally polymerizable compound has at least one thermally polymerizable functional group in one molecule. The term "thermally polymerizable functional group" as used herein refers to a functional group capable of undergoing a polymerization reaction between the same functional groups or another functional group by heating. Thermally polymerizable functional groups include hydroxyl groups, carboxyl groups, isocyanate groups, amino groups, cyclic ether groups, mercapto groups, and the like.

The thermally polymerizable compound is not particularly limited, and examples thereof include epoxy compounds, polyol compounds, isocyanate compounds, melamine compounds, urea compounds, phenol compounds and the like.

Solvent-drying type resins are resins such as thermoplastic resins that form a film only by drying the solvent added to adjust the solid content at the time of coating. When the solvent-drying type resin is added, it is possible to effectively prevent film defects on the surface coated with the coating liquid when forming the light-transmitting functional layer 13 . The solvent-drying type resin is not particularly limited, and generally thermoplastic resins can be used.

Examples of thermoplastic resins include styrene-based resins, (meth)acrylic-based resins, vinyl acetate-based resins, vinyl ether-based resins, halogen-containing resins, alicyclic olefin-based resins, polycarbonate-based resins, polyester-based resins, polyamide-based resins, cellulose derivatives, silicone-based resins, and rubbers or elastomers.

The thermoplastic resin is preferably amorphous and soluble in an organic solvent (especially a common solvent capable of dissolving a plurality of polymers and curable compounds). In particular, from the viewpoint of transparency and weather resistance, styrene-based resins, (meth)acrylic-based resins, alicyclic olefin-based resins, polyester-based resins, cellulose derivatives (cellulose esters, etc.), and the like are preferable.

<Inorganic particles>
Inorganic particles are components for improving the mechanical orientation strength and pencil orientation strength of the light-transmitting functional layer 13. Examples of inorganic particles include silica (SiO ₂ ) particles, alumina particles, titania particles, tin oxide particles, antimony-doped tin oxide (abbreviation: ATO) particles, and inorganic oxide particles such as zinc oxide particles. Among these, silica particles are preferable from the viewpoint of increasing hardness. Examples of silica particles include spherical silica particles and irregularly shaped silica particles, and among these, irregularly shaped silica particles are preferred. The term "spherical particles" as used herein means, for example, particles in the shape of a true sphere, an elliptical sphere, or the like, and the term "irregularly shaped particles" means particles having random unevenness on the surface, similar to the surface of potatoes. Since the irregular-shaped particles have a larger surface area than spherical particles, the inclusion of such irregular-shaped particles increases the contact area with the polymerizable compound and the like, and the pencil hardness of the light-transmitting functional layer 13 can be made more excellent. Whether or not the silica particles contained in the light-transmitting functional layer 13 are deformed silica particles can be confirmed by observing the cross section of the light-transmitting functional layer 13 with a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM). When spherical silica particles are used, the smaller the particle size of the spherical silica particles, the higher the hardness of the light-transmitting functional layer. In contrast, irregularly shaped silica particles are not as small as the smallest commercially available spherical silica particles, but can achieve hardness equivalent to this spherical silica.

The average particle size of the irregularly shaped silica particles is preferably 1 nm or more and 100 nm or less. Even if the average particle size of the irregularly shaped silica particles is within this range, hardness equivalent to that of spherical silica having an average particle size of 1 nm or more and 45 nm or less can be achieved. The average particle size of the irregularly shaped silica particles is obtained by measuring the maximum value (major axis) and the minimum value (minor axis) of the distance between two points on the outer periphery of the particle from an image of the cross section of the light-transmitting functional layer taken using a transmission electron microscope (TEM) or scanning transmission electron microscope (STEM), determining the particle size, excluding the maximum value and the minimum value among the particle sizes of 20 particles, and taking the remaining 18 particle sizes as the arithmetic mean value. In addition, the average particle size of the spherical silica particles is obtained by measuring the particle size of 20 particles from a cross-sectional image of the particles taken at a magnification of 10,000 to 100,000 times using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM), and taking the arithmetic mean value of the particle sizes of the 20 particles. When taking a cross-sectional photograph using a scanning transmission electron microscope (STEM) (for example, product name “S-4800 (TYPE2)”, manufactured by Hitachi High-Technologies Corporation), the detector (selection signal) is “TE”, the acceleration voltage is “30 kV”, and the emission is “10 μA”. For other conditions for photographing a cross-sectional photograph by STEM, the conditions described later can be referred to. Incidentally, the average particle size can be calculated by binarizing image data as described later.

The content of the inorganic particles in the light-transmitting functional layer 13 is preferably 20% by mass or more and 70% by mass or less. If the content of the inorganic particles is less than 20% by mass, sufficient hardness can be obtained, and if the content of the inorganic particles is 70% by mass or less, the filling rate does not increase too much and the adhesion between the inorganic particles and the resin component is good, so the hardness of the light-transmitting functional layer does not decrease.

As the inorganic particles, it is preferable to use inorganic particles (reactive inorganic particles) having photopolymerizable functional groups on their surfaces. Such inorganic particles having photopolymerizable functional groups on their surfaces can be prepared by surface-treating inorganic particles with a silane coupling agent or the like. Examples of the method for treating the surface of the inorganic particles with a silane coupling agent include a dry method in which the silane coupling agent is sprayed on the inorganic particles, and a wet method in which the inorganic particles are dispersed in a solvent and then the silane coupling agent is added to react.

<Organic particles>
Organic particles are also a component for improving the mechanical orientation strength and pencil orientation strength of the light transmissive functional layer 13, and examples of organic particles include plastic beads. Specific examples of plastic beads include polystyrene beads, melamine resin beads, acrylic beads, acrylic-styrene beads, silicone beads, benzoguanamine beads, benzoguanamine/formaldehyde condensed beads, polycarbonate beads, and polyethylene beads.

The light-transmitting functional layer 13 can be formed by using a light-transmitting functional layer composition containing a polymerizable compound and the like. The composition for the light-transmitting functional layer contains the above-described polymerizable compound and the like, and may optionally contain a solvent and a polymerization initiator. Further, conventionally known dispersants, surfactants, silane coupling agents, thickeners, anti-coloring agents, coloring agents (pigments, dyes), antifoaming agents, flame retardants, UV absorbers, adhesion promoters, polymerization inhibitors, antioxidants, surface modifiers, lubricants, etc. may be added to the composition for the light-transmitting functional layer for the purpose of increasing the hardness of the resin layer, suppressing curing shrinkage, or controlling the refractive index.

<Solvent>
Examples of solvents include alcohols (methanol, ethanol, propanol, isopropanol, n-butanol, s-butanol, t-butanol, benzyl alcohol, PGME, ethylene glycol, etc.), ketones (acetone, methyl ethyl ketone (MEK), cyclohexanone, methyl isobutyl ketone, diacetone alcohol, cycloheptanone, diethyl ketone, etc.), ethers (1,4-dioxane, dioxolane, diisopropyl ether dioxane, tetrahydrofuran, etc.), aliphatic Hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl lactate, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, butyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), amides (dimethyl) formamide, dimethylacetamide, etc.), or mixtures thereof.

<Polymerization initiator>
A polymerization initiator is a component that is decomposed by light or heat to generate radicals or ionic species to initiate or advance polymerization (crosslinking) of a polymerizable compound. Polymerization initiators used in the resin layer composition include photopolymerization initiators (e.g., photoradical polymerization initiators, photocationic polymerization initiators, photoanion polymerization initiators) and thermal polymerization initiators (e.g., thermal radical polymerization initiators, thermal cationic polymerization initiators, thermal anionic polymerization initiators), or mixtures thereof.

As described above, when the conductive film 10 is used for flexible applications, it is important to adhere the light-transmitting functional layer 13 to the light-transmitting substrate 11 and follow the light-transmitting substrate 11 during folding. In order to form the light-transmitting functional layer 13 that adheres to the light-transmitting substrate 11 and can follow the light-transmitting substrate 11 when folded, it is preferable to use an oxime ester compound as a polymerization initiator. Examples of commercially available oxime ester compounds include IRGACURE (registered trademark) OXE01, IRGACURE (registered trademark) OXE02, and IRGACURE (registered trademark) OXE03 (all manufactured by BASF Japan).

The content of the polymerization initiator in the composition for the light-transmitting functional layer is preferably 0.5 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the polymerizable compound. By setting the content of the polymerization initiator within this range, the hard coat performance can be sufficiently maintained, and curing inhibition can be suppressed.

<<Conductive Part>>
The conductive portion 12 extends linearly as shown in FIG. As used herein, the term “conductive portion” means a linear portion in which conductive fibers are confirmed and conductive from the surface when a cross section is observed using a scanning transmission electron microscope (STEM) or a transmission electron microscope (TEM). If it is difficult to confirm the interface of the conductive portion, it is preferable to perform a pretreatment generally used for electron microscope observation, such as forming a metal layer of Pt—Pd, Au, or the like on the surface of the conductive portion by sputtering. In addition, when the conductive film is dyed with osmium tetroxide, ruthenium tetroxide, or phosphotungstic acid, the interface between the organic layers becomes easier to see.

The conductive portion 12 includes a plurality of conductive fibers 14, as shown in FIG. The term “conductive fiber” as used herein means a fiber having conductivity and having a shape whose length is sufficiently longer than its thickness (e.g., diameter).

Whether or not the conductive fibers 14 are aligned along the direction D in which the conductive portion 12 extends can be confirmed using, for example, a surface fiber orientation analysis program (V.8.03) (http://www.enomae.com/FiberOri/index.htm). This program is based on Enomae, T., Han, Y.-H. and Isogai, A., "Nondestructive determination of fiber orientation distribution of fiber surface by image analysis", Nordic Pulp and Paper Research Journal 21(2): 253-259(2006) and Enomae, T., Han, Y.-H. and Isogai, A., "Fiber orientation distribution of paper surface calculated by image analysis", Proceedings of International Papermaking and Environment Conference, T ianjin, P. R. China (May 12-14), Book2, 355-368 (2004) (see http://www.enomae.com/publish.htm). In this program, a plane photograph of a conductive fiber taken by a scanning electron microscope (SEM) is binarized, then Fourier-transformed, and the Fourier-transformed image is converted to polar coordinates to calculate the average amplitude with respect to the angle, thereby creating a fiber orientation distribution. Then, this fiber orientation distribution is approximated to an ellipse, the angle formed by the major axis of the approximated ellipse and the direction D is taken as the orientation angle, and the ratio of the major axis length to the minor axis length of the approximated ellipse (major axis length/minor axis length) is calculated as the orientation strength. Specifically, 10 plane photographs of the conductive fibers of the conductive portion by SEM are taken at a magnification of 1000 to 6000 times, the fiber orientation distribution is calculated for each of the 10 photographs, and the average fiber orientation distribution is calculated by averaging the fiber orientation distributions. The orientation angle and the orientation strength are calculated from the average fiber orientation distribution according to the above. In the conductive fibers in the conductive portion, if the orientation angle is within 0° ± 10° (although the calculated orientation angle is a numerical value of 0° to 180°, 180° to 90° is read as -0° to -90°) and the orientation strength is 1.2 or more, it can be determined that the conductive fibers are aligned in the direction in which the conductive portion extends. More preferably, the orientation angle is within 0°±5°, and the orientation strength is more preferably 1.3 or more, 1.5 or more, or 1.7 or more.

The conductive portion 12 is electrically conductive from the surface of the conductive portion 12 . Whether or not the conductive portion 12 is electrically conductive from the surface of the conductive portion can be determined by obtaining the surface resistance value of the conductive portion 12 or by measuring the line resistance value.

When judging conduction from the surface resistance value of the conductive portion 12, it can be judged that the electrical conduction is obtained from the surface of the conductive portion 12 if the surface resistance value of the conductive portion 12 is less than 2000Ω/□. The surface resistance value of the conductive portion 12 is obtained as follows. A linear silver paste extending in the width direction of the conductive part 12 is applied to both ends of the conductive part 12 of the sample cut into a size of 5 mm × 100 mm so that the direction D in which the conductive part 12 extends from the conductive film 10 is the longitudinal direction. These silver pastes are then cured by heating at 130° C. for 30 minutes. In this state, a probe terminal of a tester (product name “Digital MΩ Hitester 3454-11” manufactured by Hioki Denki Co., Ltd.) is brought into contact under an environment of a temperature of 23±5° C. and a relative humidity of 30% to 70% to measure the resistance value. Specifically, the Digital MΩ Hitester 3454-11 has two probe terminals (a red probe terminal and a black probe terminal, both pin-shaped), so the red probe terminal is brought into contact with one hardened silver paste, and the black probe terminal is brought into contact with the other hardened silver paste to measure the resistance value. Then, the surface resistance value of the conductive portion is obtained from the following formula (2).
Rs=R×( _CW × _CN / _CL ) (2)
In the above formula (2), Rs is the surface resistance value (Ω/□), R is the measured resistance value (Ω), _CW is the line width (μm) of one conductive portion, _CN is the number of conductive portions, and _CL is the line length (μm) of the conductive portion.

The surface resistance value of the conductive portion 12 is preferably 3Ω/□ or more and 1000Ω/□ or less. If the surface resistance value of the conductive portion 12 is 3 Ω/□ or more, the optical performance is sufficient, and if the surface resistance value of the conductive portion 12 is 1000 Ω/□ or less, problems such as a slow response speed can be suppressed, especially in touch panel applications. More preferably, the lower limit of the surface resistance value of the conductive portion 12 is 5Ω/□ or more, or 10Ω/□ or more, and the upper limit of the surface resistance value of the conductive portion 12 is 100Ω/□ or less, 70Ω/□ or less, 60Ω/□ or less, or 50Ω/□ or less.

When determining continuity from the line resistance value of the conductive portion 12, it can be determined that electrical continuity is obtained from the surface of the conductive portion 12 if the line resistance value of the conductive portion 12 is less than 20000Ω. The line resistance value of the conductive portion 12 is obtained as follows. First, the resistance value of the sample is measured in the same manner as the surface resistance value of the conductive portion 12 . Then, the line resistance value of the conductive portion 12 is obtained from the following formula (3).
R _L =R×C _N (3)
In equation (3) above, _RL is the line resistance (Ω), R is the measured resistance (Ω), and _CN is the number of conductive portions.

It is preferable that the line resistance value of the conductive portion 12 is 15000Ω or less. If the line resistance value of the conductive portion 12 is 15000Ω or less, problems such as slow response speed can be suppressed particularly in touch panel applications. The lower limit of the line resistance value of the conductive portion 12 is more preferably 20Ω or more, 100Ω or more, or 200Ω or more, and the upper limit of the line resistance value of the conductive portion 12 is preferably 12000Ω or less, 10000Ω or less, or 8000Ω or less.

The line width W (see FIG. 3) of the conductive portion 12 is preferably 200 μm or more and 4000 μm or less. If the line width W of the conductive portion 12 is 200 μm or more, a resistance wire resistance value necessary for a sensor can be expressed, and if the line width W of the conductive portion 12 is 4000 μm or less, the conductive portion 12 is thin. The lower limit of the line width W of the conductive portion 12 is preferably 250 μm or more, 300 μm or more, or 350 μm or more, and the upper limit of the line width W1 of the conductive portion 12 is preferably 3800 μm or less, 3600 μm or less, or 3400 μm or less. The line width of the conductive portion is determined by randomly measuring the line width at 10 locations from a plan view of the conductive portion taken using a scanning electron microscope (SEM), and among the measured 10 line widths, the maximum value and the minimum value.

As the thickness of the conductive portion increases, the overlapping portion of the conductive fibers increases, so it is possible to achieve a low line resistance value, but if the conductive fibers overlap too much, the cost increases and it may become difficult to maintain a low haze value. Therefore, the line thickness of the conductive portion 12 is preferably 300 nm or less. From the viewpoint of optical properties and thinning, the conductive portion preferably has a thin line thickness as long as a low line resistance value can be maintained. The upper limit of the line thickness of the conductive portion 12 is more preferably 200 nm or less, 145 nm or less, 140 nm or less, 120 nm or less, 110 nm or less, 80 nm or less, or 50 nm or less from the viewpoint of thinning and obtaining good optical properties such as a low haze value. Also, the lower limit of the line thickness of the conductive portion 12 is preferably 10 nm or more. If the wire thickness of the conductive portion 12 is 10 nm or more, stable electrical conduction can be obtained. In order to obtain more stable electrical conduction, it is preferable that two or more conductive fibers are in contact with each other. Therefore, the lower limit of the film thickness of the conductive portion 12 is more preferably 20 nm or more or 30 nm or more.

The line thickness of the conductive part 12 is obtained by randomly measuring the thickness of 10 points from a cross-sectional photograph of the conductive part 12 taken using a scanning transmission electron microscope (STEM) or a transmission electron microscope (TEM), and taking the thickness of the measured 10 points as the arithmetic average value of the thickness at 8 points excluding the maximum value and the minimum value.

A specific method for taking cross-sectional photographs will be described below. First, a sample for cross-sectional observation is produced from the conductive film in the same manner as described above. It is preferable to sputter Pt--Pd for about 20 seconds because an STEM observation image may be difficult to see if conduction is not obtained in this sample. The sputtering time can be adjusted as appropriate, but 10 seconds is too short, and 100 seconds is too long, so that the sputtered metal forms a particle-like foreign matter image, so care must be taken. After that, using a scanning transmission electron microscope (STEM) (for example, product name “S-4800 (TYPE2)” manufactured by Hitachi High-Technologies Corporation), a cross-sectional photograph of the STEM sample is taken. When taking this cross-sectional photograph, STEM observation is performed with the detector (selection signal) set to "TE", the acceleration voltage set to "30 kV", and the emission set to "10 μA". Magnification is appropriately adjusted between 5,000 and 200,000 times while adjusting the focus and observing whether each layer can be distinguished in terms of contrast and brightness. A preferable magnification is 10,000 to 100,000 times, more preferable magnification is 10,000 to 50,000 times, and the most preferable magnification is 25,000 to 50,000 times. When taking a cross-sectional photograph, the beam monitor aperture is set to 3, the objective lens aperture is set to 3, and the W.F. D. may be 8 mm. When measuring the film thickness of the conductive portion, it is important that the interface contrast between the conductive portion and other layers (light-transmitting base material, embedding resin, etc.) can be observed as clearly as possible when observing the cross section. If this interface is difficult to see due to insufficient contrast, pretreatment generally used in electron microscope observation, such as forming a metal layer of Pt—Pd, Pt, Au, or the like on the surface of the conductive portion by sputtering, may be performed. In addition, dyeing treatment such as osmium tetroxide, ruthenium tetroxide, phosphotungstic acid or the like makes it easier to see the interface between the organic layers. Further, the interface contrast may be difficult to understand at high magnification. In that case, the low magnification is also observed at the same time. For example, observe at two high and low magnifications, such as 25,000 times and 50,000 times, or 50,000 times and 100,000 times, obtain the arithmetic average value described above at both magnifications, and further use the average value as the value of the line thickness of the conductive portion.

<Conductive fiber>
A plurality of conductive fibers 14 are present in each conductive portion 12 . Since the surfaces of the conductive portions 12 are electrically conductive, the conductive fibers 14 are in contact with each other in the thickness direction of the conductive portions 12 .

In the conductive portion 12 , it is preferable that the conductive fibers 14 contact each other to form a network structure (mesh structure) in the planar direction (two-dimensional direction) of the conductive portion 12 . A conductive path can be formed by the conductive fibers 14 forming a network structure.

The average fiber diameter of the conductive fibers 14 is preferably 30 nm or less. If the average fiber diameter of the conductive fibers 14 is 30 nm or less, the increase in the haze value of the conductive film 10 can be suppressed, and the light transmission performance is sufficient. From the viewpoint of the conductivity of the conductive portion 12, the lower limit of the average fiber diameter of the conductive fibers 14 is more preferably 5 nm or more, 7 nm or more, or 10 nm or more. Further, the upper limit of the average fiber diameter of the conductive fibers 14 is more preferably 28 nm or less, 25 nm or less, or 20 nm or less. In order to control the haze value of the conductive film 10 within a preferable range, the fiber diameter of the conductive fibers 14 is more preferably 7 nm or more and 25 nm or less.

The average fiber diameter of the conductive fibers 14 is, for example, using a transmission electron microscope (TEM) (for example, product name “H-7650”, manufactured by Hitachi High-Technologies Corporation), 50 images are taken at 100,000 to 200,000 times, the fiber diameters of 100 conductive fibers are actually measured on the imaging screen by the software attached to the TEM, and the arithmetic mean value is obtained. When measuring the fiber diameter using the above H-7650, the acceleration voltage is "100 kV", the emission current is "10 μA", the focusing lens aperture is "1", the objective lens aperture is "0", the observation mode is "HC", and the spot is "2". The fiber diameter of the conductive fiber can also be measured with a scanning transmission electron microscope (STEM) (for example, product name "S-4800 (TYPE2)", manufactured by Hitachi High-Technologies Corporation). When using STEM, 50 images are taken at 100,000 to 200,000 times, the fiber diameter of 100 conductive fibers is actually measured on the imaging screen by the software attached to STEM, and the average fiber diameter of the conductive fibers is obtained as the arithmetic mean value. When measuring the fiber diameter using the above S-4800 (TYPE2), the signal selection is "TE", the acceleration voltage is "30 kV", the emission current is "10 μA", the probe current is "Norm", the focus mode is "UHR", the condenser lens 1 is "5.0", and the W. D. to “8 mm” and Tilt to “0°”.

When measuring the fiber diameter of the conductive fibers 14, a measurement sample prepared by the following method is used. Here, since the TEM measurement requires a high magnification, it is important to reduce the concentration of the conductive fiber dispersion as much as possible so that the conductive fibers do not overlap as much as possible. Specifically, it is preferable to dilute the conductive fiber dispersion with water or alcohol in accordance with the dispersion medium so that the conductive fiber concentration is 0.05% by mass or less, or the solid content is 0.2% by mass or less. Furthermore, one drop of this diluted conductive fiber dispersion is dropped on a grid mesh with a carbon support film for TEM or STEM observation, dried at room temperature, and observed under the above conditions to obtain observation image data. Calculate the arithmetic mean value based on this. As the grid mesh with a carbon support film, a Cu grid model number "#10-1012 elastic carbon ELS-C10 STEM Cu100P grid specification" is preferable, and it is resistant to electron beam irradiation and has better electron beam transmittance than plastic support films, so it is suitable for high magnification and resistant to organic solvents. In addition, when dripping, it is preferable to place the grid mesh on a slide glass and drip it, because the grid mesh alone is too small to drip.

The fiber diameter can be obtained by actual measurement based on a photograph, or may be calculated by binarization processing based on image data. When actually measuring, you may print a photograph and enlarge it suitably. At that time, the conductive fibers are reflected with a higher density of blackness than the other components. Measurement points are measured with the outside of the contour as the starting point and the ending point. The concentration of the conductive fibers is determined by the ratio of the mass of the conductive fibers to the total mass of the conductive fiber dispersion, and the solid content is determined by the ratio of the mass of components other than the dispersion medium (conductive fibers, resin components, and other additives) to the total mass of the conductive fiber dispersion. The fiber diameter obtained using the conductive fiber-containing composition and the fiber diameter obtained by actual measurement based on the photograph are almost the same value.

The average fiber length of the conductive fibers 14 is preferably 15 μm or more and 20 μm or less in order to suppress the feeling of white turbidity. If the average fiber length of the conductive fibers 14 is 15 μm or more, a conductive portion having sufficient conductive performance can be formed, and there is no risk of cloudiness due to aggregation, an increase in haze value, or a decrease in light transmission performance. Also, if the average fiber length of the conductive fibers 14 is 20 μm or less, the filter can be coated without clogging. The lower limit of the average fiber length of the conductive fibers 14 may be 5 μm or more, 7 μm or more, or 10 μm or more, and the upper limit of the average fiber length of the conductive fibers 14 may be 40 μm or less, 35 μm or less, or 30 μm or less.

The average fiber length of the conductive fibers 14 is obtained by, for example, using the SEM function of a scanning electron microscope (SEM) (for example, product name “S-4800 (TYPE 2)”, manufactured by Hitachi High-Technologies Corporation), 10 images are taken at a magnification of 5 million to 20 million, and the fiber length of 100 conductive fibers is measured on the imaging screen using the attached software. It shall be obtained as an arithmetic mean value. When measuring the fiber length using the above S-4800 (TYPE 2), a 45° inclined sample stage was used, signal selection was set to "SE", acceleration voltage to "3 kV", emission current to "10 μA to 20 μA", SE detector to "Mix", probe current to "Norm", focus mode to "UHR", condenser lens 1 to "5.0", W.E. D. to “8 mm” and Tilt to “30°”. Since the TE detector is not used during SEM observation, the TE detector must be removed before SEM observation. The S-4800 can select between the STEM function and the SEM function, but the SEM function is used when measuring the fiber length.

When measuring the fiber length of the conductive fibers 14, a measurement sample prepared by the following method is used. First, the conductive fiber dispersion is applied to the untreated surface of a B5 size polyethylene terephthalate (PET) film having a thickness of 50 μm so that the coating amount of the conductive fiber is 10 mg / m ² , the dispersion medium is dried, and the conductive fiber is arranged on the surface of the PET film to produce a conductive film. A size of 10 mm×10 mm is cut out from the central portion of this conductive film. Then, this cut out conductive film is applied to an SEM sample stand (model number “728-45”, manufactured by Nissin EM Co., Ltd., inclined sample stand 45°, φ15 mm × 10 mm, made of M4 aluminum) having a 45° inclination. Further, Pt--Pd is sputtered for 20 to 30 seconds to obtain conduction. If there is no suitable sputtered film, the image may be difficult to see, so in that case, adjust accordingly.

The fiber length can be obtained by actual measurement based on a photograph, or may be calculated by binarization processing based on image data. When measuring based on photographs, the same method as above shall be used. The fiber length obtained using the conductive fiber-containing composition and the fiber length obtained by actual measurement based on the photograph are almost the same value.

The conductive fibers 14 are preferably at least one type of fiber selected from the group consisting of conductive carbon fibers, metal fibers such as metal nanowires, metal-coated organic fibers, metal-coated inorganic fibers, and carbon nanotubes.

Examples of the conductive carbon fibers include vapor grown carbon fibers (VGCF), carbon nanotubes, wire cups, wire walls, and the like. One or more of these conductive carbon fibers can be used.

As the metal fibers, for example, stainless steel, Ag, Cu, Au, Al, Rh, Ir, Co, Zn, Ni, In, Fe, Pd, Pt, Sn, Ti, or metal nanowires composed of alloys thereof are preferable. Among metal nanowires, silver nanowires are preferable from the viewpoint of realizing a low resistance value, being difficult to oxidize, and being suitable for wet coating. As the metal fiber, for example, a fiber produced by a wire drawing method or a cutting method in which the metal is thinly and elongated can be used. One or more of these metal fibers can be used.

When silver nanowires are used as metal fibers, silver nanowires can be synthesized by liquid phase reduction of silver salts (eg, silver nitrate) in the presence of polyols (eg, ethylene glycol) and poly(vinylpyrrolidone). Mass production of uniformly sized silver nanowires is described, for example, in Xia, Y.; et al. , Chem. Mater. (2002), 14, 4736-4745 and Xia, Y.; et al. , Nanoletters (2003) 3(7), 955-960.

There are no particular restrictions on the means for producing metal nanowires, and for example, known means such as liquid phase methods and vapor phase methods can be used. Moreover, there is no particular limitation on the specific manufacturing method, and a known manufacturing method can be used. For example, as a method for producing silver nanowires, Adv. Mater. , 2002, 14, 833-837; Chem. Mater. , 2002, 14, 4736 to 4745, etc., Japanese Patent Laid-Open No. 2006-233252 for a method for producing gold nanowires, Japanese Patent Laid-Open No. 2002-266007 for a method for producing Cu nanowires, and Japanese Patent Laid-Open No. 2004-149871 for a method for producing cobalt nanowires.

Examples of the metal-coated synthetic fibers include acrylic fibers coated with gold, silver, aluminum, nickel, titanium, or the like. One or more of these metal-coated synthetic fibers can be used.

<<<other conductive films>>>
In the conductive film 10, the conductive portion extends in one direction (direction D), but the conductive portion may extend in at least two directions. Specifically, as shown in FIG. 4, in the conductive film 20, the first conductive portion 21 linearly extends in the first direction D1, and the second conductive portion 22 linearly extends in a second direction D2 different from the first direction.

<<first conductive portion and second conductive portion>>
The first conductive portion 21 and the second conductive portion 22 may be connected as shown in FIG. 5, or may be separated. The second direction D2 may be different from the first direction D1. For example, the angle α between the first direction D1 and the second direction D2 may be 10° or more and 90° or less. The angle α (see FIG. 5) means the narrower angle between the first direction D1 and the second direction D2. The lower limit of the angle α may be 15° or more, 30° or more, or 45° or more.

The first conductive portion 21 and the second conductive portion 22 each contain a plurality of conductive fibers 14 . As shown in FIG. 6, the conductive fibers 14 in the first conductive portion 21 are aligned along the first direction D1, and the conductive fibers 14 in the second conductive portion 22 are aligned along the second direction D2.

The first conductive portion 21 and the second conductive portion 22 are the same as the conductive portion 12 except for the above, so description thereof will be omitted here.

<<Method for producing conductive film>>
The conductive film 10 can be produced, for example, as follows. First, as shown in FIG. 7A, the composition for the light-transmitting functional layer is applied to the second surface 11B of the light-transmitting substrate 11 and dried to form a coating film 31 of the composition for the light-transmitting functional layer.

Examples of the method for applying the composition for the light-transmitting functional layer include known coating methods such as spin coating, dipping, spraying, slide coating, bar coating, roll coating, gravure coating, and die coating.

Next, as shown in FIG. 7B, the coating film 31 is irradiated with ionizing radiation such as ultraviolet rays or heated to polymerize (crosslink) the polymerizable compound, thereby curing the coating film 31 to form the light-transmitting functional layer 13.

When ultraviolet rays are used as the light for curing the composition for the light-transmitting functional layer, ultraviolet rays emitted from ultrahigh-pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, carbon arcs, xenon arcs, metal halide lamps, etc. can be used. As the wavelength of ultraviolet rays, a wavelength range of 190 to 380 nm can be used. Specific examples of the electron beam source include various electron beam accelerators such as Cockcroftwald type, Vandegraft type, resonance transformer type, insulating core transformer type, linear type, dynamitron type, and high frequency type.

After forming the light-transmitting functional layer 13 on the light-transmitting substrate 11, the first surface 11A of the light-transmitting substrate 11 is coated with a conductive fiber dispersion containing the conductive fibers 14 and a dispersion medium. A contact dispenser is used to apply the conductive fiber dispersion. Specifically, as shown in FIG. 8A, while moving the discharge part 32 of the contact dispenser in the direction D relative to the light-transmitting substrate 11, the conductive fiber dispersion is discharged from the discharge part 32 along the direction D to apply the conductive fiber dispersion in a line. As a result, a linear coating portion 33 is formed. The term "contact dispenser" as used herein refers to a dispenser of a type in which a discharge part is in direct contact with a liquid pool of a conductive fiber dispersion liquid formed on a surface to be coated. In addition, "moving the ejection part of the dispenser relative to the light-transmitting substrate" means moving the ejection part of the dispenser with respect to the light-transmitting substrate, and moving the light-transmitting substrate relative to the ejection part of the dispenser. The ejection part 32 is configured to eject the conductive fiber dispersion by, for example, pressing a plunger with air pressure. Examples of the ejection part 32 include a syringe, a nozzle, and the like.

During ejection of the conductive fiber dispersion, the relative movement speed of the ejector 32 with respect to the light-transmitting substrate 11 is preferably 5 mm/second or more and 500 mm/second or less. When the relative movement speed is 5 mm/sec or more, it is possible to suppress wetting and spreading of the coated portion, and when it is 500 mm/sec or less, the conductive fiber dispersion liquid can be linearly discharged without running out. More preferably, the lower limit of the relative movement speed is 10 mm/sec or more, 15 mm/sec or more, or 20 mm/sec or more, and the upper limit is 450 mm/sec or less, 420 mm/sec or less, or 400 mm/sec or less. The term "relative movement speed of the ejection section with respect to the light-transmissive base material" used herein refers to the relative movement speed in the direction of forming the linear coating section.

The distance (coating gap) between the ejection part 32 and the light transmissive substrate 11 during ejection of the conductive fiber dispersion is preferably 5 μm or more and 80 μm or less. If the coating gap is 5 μm or more, contact between the ejection part 32 and the light-transmitting substrate 11 can be suppressed, and if it is 80 μm or less, the conductive fiber dispersion can be ejected linearly without liquid breakage. More preferably, the lower limit of the coating gap is 10 μm or more, 15 μm or more, or 20 μm or more, and the upper limit is 70 μm or less, 60 μm or less, or 50 μm or less.

The diameter of the ejection port of the ejection part 32 is preferably 20 μm or more and 200 μm or less. If the diameter of the ejection port is 20 μm or more, clogging of the ejection port with the conductive fiber dispersion can be suppressed, and if it is 200 μm or less, the conductive fiber dispersion can be suppressed from flowing out. More preferably, the lower limit of the diameter of the ejection port is 22 μm or more, 24 μm or more, or 25 μm or more, and the upper limit is 160 μm or less, 120 μm or less, or 100 μm or less.

The discharge pressure of the conductive fiber dispersion liquid when discharging the conductive fiber dispersion liquid is preferably 1 kPa or more and 50 kPa or less. When the discharge pressure is 1 kPa or more, the conductive fiber dispersion can be discharged without clogging, and when it is 50 kPa or less, excessive pressure applied to the conductive fiber dispersion can be suppressed. More preferably, the lower limit of the discharge pressure is 2 kPa or more, 4 kPa or more, or 5 kPa or more, and the upper limit is 40 kPa or less, 30 kPa or less, or 20 kPa or less.

In addition to the conductive fibers 14 and the dispersion medium, the conductive fiber dispersion liquid may contain a resin component made of a thermoplastic resin or a polymerizable compound. The term “resin component” used herein refers to a resin (however, it does not include a resin (e.g., polyvinylpyrrolidone, etc.) that constitutes an organic protective layer formed around the conductive fiber during synthesis of the conductive fiber, such as for preventing self-welding of the conductive fibers covering the conductive fiber or reaction with substances in the atmosphere), as well as a component that can be polymerized into a resin like a polymerizable compound.

The dispersion medium may be either an aqueous dispersion medium or an organic dispersion medium. However, if the content of the resin in the conductive fiber dispersion is too high, the resin may enter between the conductive fibers, degrading the conduction of the conductive portion. In particular, when the film thickness of the conductive portion is thin, the conduction of the conductive portion tends to deteriorate. On the other hand, the use of an organic dispersion medium reduces the resin content in the conductive fiber dispersion as compared with the case of using an aqueous dispersion medium. Therefore, when forming the conductive portion 12 having a thin film thickness of, for example, 300 nm, it is preferable to use an organic dispersion medium. The organic dispersion medium may contain less than 10% by mass of water.

Although the organic dispersion medium is not particularly limited, it is preferably a hydrophilic organic dispersion medium. Examples of organic dispersion media include saturated hydrocarbons such as hexane; aromatic hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone and diisobutyl ketone; esters such as ethyl acetate and butyl acetate; amides such as acetamide; and halogenated hydrocarbons such as ethylene chloride and chlorobenzene. Among these, alcohols are preferable from the viewpoint of the stability of the conductive fiber dispersion.

Thermoplastic resins that may be contained in the conductive fiber dispersion include acrylic resins; polyester resins such as polyethylene terephthalate; aromatic resins such as polystyrene, polyvinyl toluene, polyvinylxylene, polyimide, polyamide, and polyamideimide; polyurethane resins; epoxy resins; system resin and the like.

The polymerizable compound that may be contained in the conductive fiber dispersion includes the same polymerizable compounds as those described in the section of the light-transmitting functional layer 13, so description thereof will be omitted here.

After that, as shown in FIG. 8B, the coated portion 33 is dried to obtain the linear conductive portion 12 . Thereby, the conductive film 10 is obtained.

In the case of obtaining a conductive film, first, while moving the discharge part 32 of the contact dispenser in the first direction D1 relative to the light-transmitting substrate 11, the conductive fiber dispersion is applied from the discharge part 32 along the first direction D1 to form a linear first coating part. Similarly, while moving the ejection part 32 in the second direction D2 relative to the light-transmitting substrate 11, the conductive fiber dispersion is applied from the ejection part 32 along the second direction D2 to form a linear second coating part. After that, the first coated portion and the second coated portion are dried to obtain the linear first conductive portion 21 and the linear second conductive portion 22 . Thereby, the conductive film 20 is obtained.

Normally, when applying a conductive fiber dispersion, a die coating method or a bar coating method is used, but when a conductive layer is formed using a die coating method or a bar coating method, the conductive fibers are arranged randomly. Therefore, even if the conductive layer is etched to form a patterned linear conductive portion, the conductive fibers are randomly arranged. In addition, when the conductive fiber dispersion is applied by a non-contact dispenser or an inkjet method to form a linear conductive portion, the conductive fibers have directionality for each droplet, but the applied conductive fibers as a whole have no directionality, so the conductive fibers in the conductive portion are randomly arranged. Furthermore, even when the conductive fiber dispersion is applied by screen printing to form a linear conductive portion, the conductive fibers in the conductive portion are randomly arranged. On the other hand, when the conductive fibers are arranged along a certain direction, the wire resistance value is lower than when the conductive fibers are randomly arranged. According to this embodiment, the conductive fiber dispersion liquid containing the conductive fibers 14 is applied from the discharge part 32 to the first surface 11A side of the light-transmissive substrate 11 while the discharge part 32 of the contact-type dispenser is moved relative to the light-transmissive base material 11. Therefore, the conductive fibers 14 can be arranged along the movement direction of the discharge part 32 or the light-transmissive base material 11. This is probably because the discharge part 32 of the dispenser has a narrow opening, so that when the conductive fiber dispersion liquid is applied, the conductive fibers do not lie down, and the longitudinal direction of the conductive fibers 14 is oriented in the normal direction of the light-transmitting substrate 11. It is considered that the conductive fibers are applied. Therefore, since the line resistance value of the conductive portion 12 can be reduced, the content of conductive fibers in the conductive portion 12 can be reduced. As a result, it is possible to realize a desired line resistance value while reducing costs.

As described above, when a conductive dispersion is applied by a die coating method or a bar coating method, a layered conductive portion is formed. Therefore, patterning by etching is required to form a linear conductive portion. Since patterning by etching removes unnecessary portions of the conductive portion, the conductive fibers contained in the portions removed by etching are wasted. On the other hand, according to the present embodiment, since the conductive fiber dispersion liquid is directly applied linearly, patterning by etching is not necessary. As a result, waste of the conductive fibers 14 can be reduced, and cost reduction can be achieved. Moreover, since etching is not required, the number of steps is reduced, and the manufacturing time can be shortened.

According to the present embodiment, the conductive fibers 14 in the conductive portion 12 are arranged along the direction D in which the conductive portion 12 extends, so the line resistance value of the conductive portion 12 can be reduced, and as a result, the content of the conductive fibers 14 in the conductive portion 12 can be reduced. As a result, it is possible to realize a desired line resistance value while reducing costs.

According to this embodiment, since the conductive fibers 14 are used, unlike ITO, it is possible to provide the conductive film 10 that is hard to crack even when bent.

Although the use of the conductive film according to the present embodiment is not particularly limited, it can be used by incorporating it into an image display device having a touch panel. FIG. 10 is a schematic configuration diagram of an image display device according to this embodiment.

<<<Image display device>>>
The conductive film 10 and the conductive film 20 can be incorporated into an image display device for use. FIG. 9 is a schematic configuration diagram of an image display device according to this embodiment. The image display device 40 shown in FIG. 9 includes a display element 50, a circularly polarizing plate 60, a touch sensor 70, and a cover member 80 in this order facing the observer. The display element 50 and the circularly polarizing plate 60, the circularly polarizing plate 60 and the touch panel 70, and the touch panel 70 and the cover member 80 are adhered via adhesive layers 91-93. "Adhesion" as used herein is a concept including adhesion.

<<Display element>>
Examples of the display element 50 include liquid crystal elements, organic light emitting diode elements (hereinafter also referred to as "OLED elements"), inorganic light emitting diode elements, micro LEDs, plasma elements, and the like. A known organic light emitting diode element can be used as the organic light emitting diode element. Further, the liquid crystal display element may be an in-cell touch panel liquid crystal display element having a touch panel function inside the element.

<< Circularly polarizing plate >>
Since the circularly polarizing plate 60 has a function of suppressing reflection of external light, the circularly polarizing plate 60 is particularly effective when an OLED element is used as the display element. The circularly polarizing plate 60 includes, for example, a first retardation film, an adhesive layer, a second retardation film, an adhesive layer, and a polarizing plate in this order facing the observer.

The thickness of the circularly polarizing plate 60 is preferably 100 μm or less from the viewpoint of thinning. The lower limit of the thickness of the circularly polarizing plate 60 is preferably 20 μm or more, 30 μm or more, or 50 μm or more from the viewpoint of workability due to strength reduction. Moreover, the upper limit of the thickness of the circularly polarizing plate 60 is more preferably 95 μm or less, 90 μm or less, or 80 μm or less. The thickness of the circularly polarizing plate 60 is obtained by photographing the cross section of the circularly polarizing plate 60 using a scanning electron microscope (SEM), measuring the thickness of the circularly polarizing plate 60 at 10 locations in the image of the cross section, and calculating the arithmetic average value of only the 10 locations.

The circularly polarizing plate 60 may be incorporated into the image display device by either chip-cut method or roll-to-panel method. The chip-cut method is a method in which a circularly polarizing plate of a predetermined size is cut out from a roll-shaped circularly polarizing plate according to the size of the image display device, and is attached to a cover member such as glass via an adhesive layer. Further, the roll-to-panel method is a method in which a roll-shaped circularly polarizing plate is cut while being sent out in a production line of an image display device, and adhered to a cover member such as glass via an adhesive layer.

<<Touch Panel>>
The touch panel 70 includes a conductive film 71 and the conductive film 10 arranged closer to the viewer than the conductive film 71 . The conductive film 71 has substantially the same structure as the conductive film 10 and includes a light transmissive base material 72 , a conductive portion 73 and a light transmissive functional layer 74 . The light-transmitting base material 72 is the same as the light-transmitting base material 11, the conductive portion 73 is the same as the conductive portion 12, and the light-transmitting functional layer 74 is the same as the light-transmitting functional layer 13, so the description thereof will be omitted here.

<<Cover member>>
A surface 80A of the cover member 80 serves as a surface 40A of the image display device 40 . The cover member 80 may be a cover glass or a cover film made of resin. When the image display device 40 has flexibility, the cover member 80 is preferably made of flexible glass or flexible resin. Examples of flexible resins include polyimide-based resins, polyamide-imide-based resins, polyamide-based resins, polyester-based resins (e.g., polyethylene terephthalate resins and polyethylene naphthalate resins), and mixtures of two or more of these resins.

<<adhesion layer>>
The adhesive layers 91 to 93 can be composed of a cured product of a liquid ionizing radiation curable adhesive (eg, OCR: Optical Clear Resin) containing a polymerizable compound or an adhesive (eg, OCA: Optical Clear Adhesive).

EXAMPLES In order to describe the present invention in detail, examples are given below, but the present invention is not limited to these descriptions.

<Preparation of composition for hard coat layer>
First, a hard coat layer composition 1 was obtained by blending each component so as to obtain the composition shown below.
(Composition 1 for hard coat layer)
・A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (trade name “KAYARAD PET-30”, manufactured by Nippon Kayaku Co., Ltd.): 30 parts by mass ・Polymerization initiator (trade name “Irgacure 184”, manufactured by BASF Japan): 1.5 parts by mass ・Methyl ethyl ketone (MEK): 50 parts by mass ・Cyclohexanone: 18.5 parts by mass

<Preparation of silver nanowire dispersion>
(Silver nanowire dispersion liquid 1)
Ethylene glycol as an alcohol solvent, silver nitrate as a silver compound, sodium chloride as a chloride, sodium bromide as a bromide, sodium hydroxide as an alkali metal hydroxide, aluminum nitrate nonahydrate as an aluminum salt, and a copolymer of vinylpyrrolidone and diallyldimethylammonium nitrate as an organic protective agent (a copolymer of 99% by weight vinylpyrrolidone and 1% by weight diallyldimethylammonium nitrate, weight average molecular weight 130,000). prepared.

Solution A was prepared by adding and dissolving 0.041 g of sodium chloride, 0.0072 g of sodium bromide, 0.0506 g of sodium hydroxide, 0.0416 g of aluminum nitrate nonahydrate, and 5.24 g of a copolymer of vinylpyrrolidone and diallyldimethylammonium nitrate in 540 g of ethylene glycol at room temperature. In a separate vessel, 4.25 g of silver nitrate was added and dissolved in 20 g of ethylene glycol to obtain solution B. In this example, the Al/OH molar ratio was 0.0876 and the OH/Ag molar ratio was 0.0506.

After the temperature of the total amount of the solution A was raised from room temperature to 115° C. with stirring, the total amount of the solution B was added to the solution A over 1 minute. After the addition of solution B was completed, the mixture was maintained at 115° C. for 24 hours while stirring. The reaction was then cooled to room temperature. After cooling, 10 times the amount of acetone was added to the reaction liquid, and the mixture was stirred for 10 minutes and allowed to stand for 24 hours. After standing, a concentrate and a supernatant were observed, so the supernatant was carefully removed with a pipette to obtain a concentrate.

500 g of pure water was added to the resulting concentrate and stirred for 10 minutes to disperse the concentrate, then 10 times the amount of acetone was added, and after stirring, the mixture was allowed to stand for 24 hours. After standing, the concentrate and the supernatant were newly observed, so the supernatant was carefully removed with a pipette. Since an excessive amount of the organic protective agent is unnecessary for obtaining good electrical conductivity, this washing operation was repeated 1 to 20 times as necessary to thoroughly wash the solid content.

Pure water was added to the washed solid to obtain a dispersion of the solid. This dispersion liquid was fractionated, the solvent pure water was volatilized on an observation table, and then observed with a high-resolution FE-SEM (high-resolution field emission scanning electron microscope). As a result, it was confirmed that the solid content was silver nanowires.

Isopropyl alcohol was added to the washed silver nanowires to obtain a silver nanowire dispersion liquid 1 . When the average fiber diameter and the average fiber length of the silver nanowires in the silver nanowire dispersion 1 were measured, the average fiber diameter of the silver nanowires was 45 nm and the average fiber length was 15 μm. Also, the concentration of silver nanowires in the silver nanowire dispersion liquid 1 was 1.5 mg/ml.

The average fiber diameter of the silver nanowires was obtained by taking 50 images at 100,000 to 200,000 times using a transmission electron microscope (TEM) (product name “H-7650”, manufactured by Hitachi High-Technologies Co., Ltd.), measuring the fiber diameters of 100 conductive fibers on the imaging screen using software attached to the TEM, and obtaining the arithmetic mean value. When measuring the fiber diameter, the acceleration voltage was "100 kV", the emission current was "10 μA", the focusing lens aperture was "1", the objective lens aperture was "0", the observation mode was "HC", and the spot was "2". In addition, the average fiber length of the silver nanowires was obtained by using a scanning electron microscope (SEM) (product name “S-4800 (TYPE2)”, manufactured by Hitachi High-Technologies Corporation) at a magnification of 5 million to 20 million times. When measuring the fiber length, the signal selection was set to "SE", the acceleration voltage was set to "3 kV", the emission current was set to "10 μA", and the SE detector was set to "mixed". Silver Nano Wire's fiber -length fibers use the SEM function of a scanning electron microscope (SEM) (product name "S -4800 (TYPE2)", manufactured by Hitachi High Technologies), 10 to 20 million times, and 100 pieces on the attached software on the imaging screen. The silver nano wire fiber length was measured, and among the 100 silver nano wire fibers, the average value of 98 arithmetic excluding the maximum and minimum values. When measuring the fiber length, a 45° inclined sample table was used, signal selection was set to "SE", acceleration voltage was set to "3 kV", emission current was set to "10 μA to 20 μA", SE detector was set to "Mix", probe current was set to "Norm", focus mode was set to "UHR", condenser lens 1 was set to "5.0", W.E. D. was set to "8 mm" and Tilt was set to "30°". Note that the TE detector was removed in advance. When measuring the fiber diameter of silver nanowires, a measurement sample prepared by the following method was used. First, silver nanowire dispersion liquid 1 was diluted with ethanol to a concentration of silver nanowires of 0.05% by mass or less in accordance with the dispersion medium. Furthermore, one drop of this diluted silver nanowire dispersion 1 was dropped on a grid mesh with a carbon support film for TEM or STEM observation (Cu grid model number “#10-1012 elastic carbon ELS-C10 STEM Cu100P grid specification”), dried at room temperature, and observed under the above conditions to obtain observation image data. Based on this, an arithmetic mean value was obtained. When measuring the fiber length of silver nanowires, a measurement sample prepared by the following method was used. First, the silver nanowire dispersion liquid 1 was applied to the untreated surface of a B5 size polyethylene terephthalate (PET) film having a thickness of 50 μm so that the coating amount of the silver nanowires was 10 mg/m ² , the dispersion medium was dried, and the conductive fibers were arranged on the PET film surface to prepare a conductive film. A size of 10 mm×10 mm was cut from the central portion of this conductive film. Then, this cut-out conductive film was applied to a SEM sample stage (model number “728-45”, manufactured by Nissin EM Co., Ltd., inclined sample stage 45°, φ15 mm × 10 mm, made of M4 aluminum) having a 45° inclination, and was attached flat to the surface of the stage using silver paste. Further, Pt--Pd was sputtered for 20 to 30 seconds to obtain conduction. The fiber diameter and fiber length of silver nanowires described below were also obtained in the same manner.

(Silver nanowire dispersion liquid 2)
A silver nanowire dispersion 2 was obtained in the same manner as the silver nanowire dispersion 1, except that the synthesis conditions and additives were adjusted to obtain silver nanowires having an average fiber diameter of 35 nm and an average fiber length of 15 μm.

(Silver nanowire dispersion 3)
A silver nanowire dispersion 3 was obtained in the same manner as the silver nanowire dispersion 1 except that the synthesis conditions and additives were adjusted to obtain silver nanowires having an average fiber diameter of 30 nm and an average fiber length of 15 μm.

<Example 1>
First, a 48 μm-thick polyethylene terephthalate film (trade name “Cosmoshine (registered trademark) A4100”, manufactured by Toyobo Co., Ltd.) having an underlayer on one side as a light-transmitting substrate was prepared, and the hard coat layer composition 1 was applied to the underlayer side of the polyethylene terephthalate film to form a coating film. Next, dry air at 50°C was passed through the formed coating film at a flow rate of 0.5 m/s for 15 seconds, and then dry air at 70°C was passed through at a flow rate of 10 m/s for 30 ^seconds to dry the coating film.

After forming the hard coat layer, on the unprocessed surface on the opposite side of the formation of the hard court layer in the polyethylene televible film, using the contact -type dispenser (product name "SUPERς (registered trademark) CMIII", manufactured by Musashi Engineering Co., Ltd.), under the following conditions. The silver nano wire dispersion 1 was discharged so that the line thickness at the time of applying was 182 μm, applied to a linear, and 90 linear coating portions parallel to each other were formed.
(Discharge condition)
・Discharge pressure: 5kPa
・Discharge port diameter: 100 μm
・Coating gap: 50 μm
・PET film moving speed: 20 mm/sec

After that, dry air at 40°C was passed through the formed coated portion at a flow rate of 0.5 m/s for 15 seconds, and then dry air at 70°C was passed through at a flow rate of 15 m/s for 30 seconds to dry the coated portion, thereby evaporating the solvent in the coated portion. As a result, 90 parallel conductive portions composed of the dried coated portions were formed on the surface of the polyethylene terephthalate film to obtain a conductive film. Each conductive portion had a line length of 100 mm and a line width of 280 μm. The interval between the conductive portions (the width of the portion where no conductive portion is formed) was 280 μm.

The line width of the conductive portion according to Example 1 was obtained by randomly measuring the line width at 10 points from a plan view of the conductive portion taken using a scanning electron microscope (SEM), and among the measured 10 line widths, the arithmetic average value of the line widths at 8 points excluding the maximum and minimum values. A concrete plane photograph was taken by the following method. First, a sample for planar observation was produced from the conductive film. Specifically, a conductive film cut into a size of 10 mm×10 mm was placed on an aluminum sample stage via a conductive tape (product name “carbon double-sided tape for SEM” manufactured by Nissin EM Co., Ltd.). Conductive colloidal graphite (product number “16053”, Pella Inc., Redding CA, USA) was applied to areas other than the observation site, and an ion sputtering apparatus (product name “E-1030”, manufactured by Hitachi High-Technologies Corporation) was used to form a platinum vapor deposition layer to obtain a sample for SEM. After that, using the SEM function of a scanning transmission electron microscope (STEM) (product name “S-4800 (TYPE2)”, manufactured by Hitachi High-Technologies Corporation), a planar photograph of the SEM sample was taken. When measuring this plane photograph, a 45° inclined sample table was used, signal selection was set to "SE", acceleration voltage was set to "3 kV", emission current was set to "10 μA to 20 μA", SE detector was set to "Mix", probe current was set to "Norm", focus mode was set to "UHR", condenser lens 1 was set to "5.0", W.E. D. was set to "8 mm" and Tilt was set to "30°". Since the TE detector was not used during SEM observation, the TE detector was removed before SEM observation. Although the S-4800 can select the STEM function or the SEM function, the SEM function was used when measuring the line width. The line length of the conductive portion according to Example 1 was also measured in the same manner as the line width. Further, the line width and line length of the conductive portion were measured by this method not only in Example 1 but also in all of the subsequent Examples and Comparative Examples.

<Example 2>
In Example 2, a conductive film was obtained in the same manner as in Example 1, except that silver nanowire dispersion 2 was used instead of silver nanowire dispersion 1.

<Example 3>
In Example 3, a conductive film was obtained in the same manner as in Example 1, except that silver nanowire dispersion 3 was used instead of silver nanowire dispersion 1.

<Example 4>
In Example 4, a conductive film was obtained in the same manner as in Example 1, except that the PET film moving speed was 5 mm/sec and the line width of the conductive portions and the interval between the conductive portions were 620 μm.

<Comparative Example 1>
In Comparative Example 1, a conductive film was obtained in the same manner as in Example 1, except that the silver nanowire dispersion liquid 1 was applied using a bar coater instead of the dispenser, and then laser-etched. Specifically, first, using a bar coater, silver nanowire dispersion 1 was applied to the untreated surface of the polyethylene terephthalate film opposite to the surface on which the hard coat layer was formed, to form a coating film on the entire surface of the polyethylene terephthalate film.

Next, dry air at 40°C was passed through the formed coating film at a flow rate of 0.5 m/s for 15 seconds, and then dry air at 70°C was passed at a flow rate of 15 m/s for 30 seconds to dry the film, thereby evaporating the solvent in the coating film. Thus, a dried conductive portion was formed on the surface of the polyethylene terephthalate film.

After forming the conductive layer, the conductive layer was patterned by irradiating laser light under the following conditions to sublimate and remove the silver nanowires present in the conductive layer so that a linear conductive portion extending along the flow direction of the polyethylene terephthalate film was formed. As a result, a conductive film having a patterned conductive portion was obtained. The dimensions of the conductive portion of the conductive film according to Comparative Example 1 were the same as those of the conductive portion of the conductive film according to Example 1.
(Laser light irradiation conditions)
・Type: _YVO4
・Wavelength: 1064 nm
・Pulse width: 8 to 10 ns
・Frequency: 100kHz
・Spot diameter: 30 μm
・Pulse energy: 16 μJ
・Processing speed: 1200mm/sec

<Silver nanowire alignment evaluation>
It was evaluated whether the silver nanowires in the conductive portions of the conductive films according to Examples 1 to 4 and Comparative Example 1 were aligned along the direction in which the conductive portions extend. Specifically, first, using the SEM function of a scanning transmission electron microscope (product name “S-4800 (TYPE2)”, manufactured by Hitachi High-Technologies Corporation), 10 photographs of the conductive portion were taken at a magnification of 1000 to 6000. Then, in each photograph of the conductive portion, the orientation angle and orientation strength were calculated using the surface fiber orientation analysis program (V.8.03). In the conductive portion, when the orientation angle of the silver nanowires is within 0° ± 10° and the orientation strength is 1.2 or more, the silver nanowires are arranged in the direction in which the conductive portion extends. It is assumed that the silver nanowires are not arranged in the direction in which the The evaluation criteria were as follows.
○: The silver nanowires in the conductive portion were arranged along the direction in which the conductive portion extends.
x: The silver nanowires in the conductive portion were not aligned along the direction in which the conductive portion extends.

<Surface resistance/line resistance measurement>
In the conductive films according to Examples 1 to 4 and Comparative Example 1, the surface resistance value and line resistance value of the conductive portion were measured. Specifically, first, a linear silver paste extending in the width direction of the conductive portion so as to straddle all the conductive portions was applied to both ends of the sample cut into a rectangular shape having a length of 100 mm in the direction in which the conductive portion extends and a width including 10 conductive portions (4 in Example 4). These silver pastes were then cured by heating at 130° C. for 30 minutes. In this state, measurement can be performed by contacting a probe terminal of a tester (product name: “Digital MΩ Hitester 3454-11” manufactured by Hioki Electric Co., Ltd.) under an environment of 23° C. temperature and 50% relative humidity. Specifically, since the Digital MΩ Hitester 3454-11 has two probe terminals (a red probe terminal and a black probe terminal, both of which are pin-shaped), the resistance value R of the conductive part was measured by bringing the red probe terminal into contact with the hardened silver paste of one of the conductive parts, and bringing the black probe terminal into contact with the hardened silver paste of the other conductive part. In Examples 1 to 3 and Comparative Example 1, the line width _CW of one conductive portion was 280 μm, the number of conductive portions _CN was 10, and the line length _CL of the conductive portion was 100000 μm (100 mm). As _m (100 mm) _, the surface resistance value was obtained based on the _above formula (2). Further, in Examples 1 to 3 and Comparative Example 1, the number of conductive portions C _N was set to 10, and in Example 4, the number of conductive portions C _N was set to four, and the line resistance value was obtained based on the above formula (3). The surface resistance value was the arithmetic mean of the surface resistance values of 3 times out of 5 times excluding the maximum and minimum values, and the line resistance value was the arithmetic mean value of the line resistance values of 3 times out of 5 times excluding the maximum and minimum values.

<Haze value measurement>
In the conductive films according to Examples 1 to 4 and Comparative Example 1, a haze meter (product name "HM-150", manufactured by Murakami Color Research Laboratory Co., Ltd.) was used to measure the haze value (total haze value) of the conductive film in accordance with JIS K7136: 2000 in an environment at a temperature of 23 ° C. and a relative humidity of 50%. The haze value is a value when the entire conductive film is measured, and after cutting into a size of 50 mm × 100 mm so that the entire conductive part is included, in a state where there are no curls or wrinkles, fingerprints, dust, etc., in the conductive films according to Examples 1 to 4 and Comparative Example 1, the conductive part side is the non-light source side, and the longitudinal direction of the conductive part is horizontal. The haze value was measured five times for one sheet of the conductive film, and was taken as the arithmetic mean value of the values obtained by measuring three times excluding the maximum and minimum values.

The results are shown in Table 1 below.

As shown in Table 1, in the conductive films of Examples 1 to 4, the silver nanowires in the conductive portion were aligned along the direction in which the conductive portion extends, so the line resistance value in the conductive portion was lower than in Comparative Example 1. As a result, the silver nanowires can be reduced from the conductive portion in the conductive films according to Examples 1 to 4, so that the desired line resistance value and surface resistance value can be achieved, and the cost can be reduced.

Regarding the fiber diameter of the silver nanowires of the conductive films according to Examples 1 to 4, each conductive film was observed with a scanning electron microscope (SEM) as follows, and the results obtained from the above composition were compared.

Using the SEM function of a scanning electron microscope (SEM) (product name “S-4800 (TYPE2)”, manufactured by Hitachi High-Technologies Co., Ltd.), 50 images were taken at 10,000 to 200,000 times, and the fiber diameter of 100 conductive fibers was measured on the imaging screen using the attached software. When measuring the fiber diameter, a sample stage inclined at 45° was used, signal selection was set to "SE", acceleration voltage was set to "3 kV", emission current was set to "10 μA to 20 μA", SE detector was set to "mix", probe current was set to "Norm", focus mode was set to "UHR", condenser lens 1 was set to "5.0", W.E. D. was set to "8 mm" and Tilt was set to "30°". Since the TE detector is not used during SEM observation, the TE detector must be removed before SEM observation. Although the S-4800 can select the STEM function or the SEM function, the SEM function was used when measuring the fiber diameter.

DESCRIPTION OF SYMBOLS 10... Conductive film 10A... Front surface 10B... Back surface 11... Light-transmitting base material 12... Conductive part 13... Light-transmitting functional layer 14... Conductive fiber 32... Discharging part 40... Image display device 50... Display element 70... Touch panel

Claims (8)

A method for producing a conductive film comprising a light-transmitting substrate and a patterned conductive portion provided on the first surface side of the light-transmitting substrate,
A conductive fiber dispersion containing conductive fibers is discharged from the discharge unit to the first surface side of the light-transmissive substrate while moving the discharge unit of the contact-type dispenser relatively to the light-transmissive substrate, and applying the conductive fiber dispersion linearly .
A method for producing a conductive film , wherein the ejection port of the ejection part has a diameter of 20 μm or more and 200 μm or less . 2. The method for producing a conductive film according to claim 1, wherein a relative movement speed of said discharging part with respect to said light-transmitting substrate is 5 mm/sec or more and 500 mm/sec or less when said conductive fiber dispersion is discharged. A conductive film comprising a light-transmitting substrate and a patterned conductive portion provided on the first surface side of the light-transmitting substrate,
The conductive portion includes a plurality of conductive fibers and is formed in a linear shape,
The conductive fibers in the conductive portion are arranged along the direction in which the conductive portion extends,
The orientation angle of the conductive fibers is within 0° ± 10°,
A conductive film, wherein the orientation strength of the conductive fibers is 1.2 or more . The conductive film according to claim 3, wherein the conductive portion has a line width of 100 µm or more and 4000 µm or less. A sensor comprising the conductive film according to claim 3 or 4. A touch panel comprising the conductive film according to claim 3 or 4. a display element;
The conductive film according to claim 3 or 4 or the touch panel according to claim 6, which is arranged closer to the viewer than the display element;
An image display device. 8. The image display device according to claim 7, wherein said display element is an organic light emitting diode element.

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