JP2021057158A - Conductive film - Google Patents

Abstract

To provide a conductive film having a conductive thin wire excellent in the flexure property that does not generate disconnection even when bended, in addition to have small electric resistance.SOLUTION: A conductive film has a flexible substrate and a conductive thin line containing a plurality of metal particles dispersed in a polymeric disposed on a flexible substrate. In a vertical cross section of the conductive thin line in a direction orthogonal to a direction in which the conductive thin line extends, when a radius of a minimum inclusion circle containing all the plurality of metal particles is set to R, a region of distance 0.2R or smaller from a center of the minimum inclusion circle is to a first region, a region of a distance larger than 0.2R and R or smaller from the center of the minimum inclusion circle is set to a second region, an average diameter of the plurality of metal particles in the first region is set to Da, and an average particle size of the plurality of metal particles in the second region is set to Db, Db/Da>1.5 is satisfied.SELECTED DRAWING: Figure 2

Description

The present invention relates to a conductive film having a conductive thin wire containing a polymer and a plurality of metal particles, and more particularly to a conductive film having a conductive fine wire having an adjusted particle size distribution of the metal particles.

Conductive films having conductive thin wires (thin wire-like wiring showing conductivity) are widely used in various applications such as touch panels, solar cells, and EL (electroluminescence) elements. In particular, in recent years, the mounting rate of touch panels on mobile phones and mobile game devices has been increasing, and the demand for conductive films for capacitive touch panels capable of detecting multiple points is rapidly expanding.
As shown in Patent Document 1, for example, as shown in Patent Document 1, the conductive thin wire of the conductive film is subjected to an exposure treatment, a development treatment, and the like in sequence on a photosensitive layer containing silver halide to be conductive containing metallic silver. A thin line is formed.

JP-A-2007-129205

In recent years, conductive films may be used even in a bent state. For this reason, in the conductive film, in addition to having a small electric resistance, the conductive thin wire is required to have bendability so that the wire does not break even when bent.
However, in Patent Document 1, no consideration is given to the performance when the conductive thin wire is bent.
In view of the above circumstances, it is an object of the present invention to provide a conductive film having a conductive thin wire having excellent bendability, which does not cause disconnection even when bent, in addition to having a small electric resistance.

In order to solve the above-mentioned problems, the present invention comprises a flexible base material, a conductive thin wire arranged on the flexible base material and containing a plurality of metal particles dispersed in a polymer, and the like. In the vertical cross section of the conductive thin wire in the direction orthogonal to the direction in which the conductive thin wire extends, the radius of the minimum inclusion circle containing all the plurality of metal particles is R, and the distance from the center of the minimum inclusion circle. The region of 0.2R or less is defined as the first region, the region of more than 0.2R R or less from the center of the minimum inclusion circle is defined as the second region, and the average particle size of the plurality of metal particles in the first region is defined as the first region. It provides a conductive film in which Db / Da> 1.5, where Da is and the average particle size of the plurality of metal particles in the second region is Db.
The average particle size Da of the plurality of metal particles in the first region and the average particle size Db of the plurality of metal particles in the second region are preferably Db / Da> 3.

The ratio of the plurality of metal particles contained in the conductive thin wire is preferably 70% by volume to 90% by volume.
The average particle size Da of the plurality of metal particles in the first region is preferably 50 nm or more and 200 nm or less.
The flexible substrate is preferably composed of polyethylene terephthalate.
The plurality of metal particles preferably contain silver.
It is preferable that the plurality of metal particles are all composed of silver.
The line width of the conductive thin wire is preferably 1.0 μm or more and less than 5.0 μm.
The thickness of the conductive thin wire is preferably 0.5 μm or more and less than 3.0 μm.

According to the present invention, it is possible to provide a conductive film having a conductive thin wire having excellent bendability, which does not cause disconnection even when bent, in addition to having a small electric resistance.

It is a schematic perspective view which shows an example of the conductive film of embodiment of this invention. It is a schematic cross-sectional view which shows an example of the conductive film of embodiment of this invention. It is a top view which shows an example of the mesh pattern formed by the conductive thin line of the conductive film of embodiment of this invention.

Hereinafter, the conductive film of the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.
It should be noted that the figures described below are exemplary for explaining the present invention, and the present invention is not limited to the figures shown below.
In the following, "~" indicating the numerical range includes the numerical values described on both sides. For example, when ε is a numerical value α to a numerical value β, the range of ε is a range including the numerical value α and the numerical value β, and is α ≦ ε ≦ β in mathematical symbols.
Angles such as "specific numerical angles", "parallel", "vertical" and "orthogonal" include error ranges generally tolerated in the art, unless otherwise stated.

<Conductive film>
FIG. 1 is a schematic perspective view showing an example of a conductive film according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing an example of a conductive film according to an embodiment of the present invention.
The conductive film 10 has a flexible base material 12 and a conductive thin wire 14 arranged on the surface 12a of the flexible base material 12. Although two conductive thin wires 14 extending in one direction are shown in FIG. 1, the arrangement form of the conductive thin wires 14 and the number thereof are not particularly limited.
As shown in FIG. 2, the conductive thin wire 14 contains a polymer 16 and a plurality of metal particles 18. In the conductive thin wire 14, a plurality of metal particles 18 are dispersed in the polymer 16.
The shape of the metal particles 18 is not limited to the particle shape, and may be, for example, a form in which the metal particles 18 are fused and partially or wholly bonded.

1 and 2 show a vertical cross section Ac of the conductive thin wire 14 in the direction DW orthogonal to the direction DL in which the conductive thin wire 14 extends.
The vertical cross section Ac of the conductive thin wire 14 is a cross section when the conductive thin wire 14 is cut at a plane orthogonal to the extending direction DL. That is, the vertical cross section Ac of the conductive thin wire 14 is a cross section when the conductive thin wire 14 is cut in a plane perpendicular to the surface 14a of the conductive thin wire 14 along the direction DW orthogonal to the direction DL in which the conductive thin wire 14 extends. is there.
In the vertical cross section Ac, the radius of the minimum inclusion circle S containing all of the plurality of metal particles 18 is defined as R, and the region of 0.2 R or less from the center C of the minimum inclusion circle S is defined as the first region Qa. A region having a distance of more than 0.2R and R or less from the center C of S is defined as a second region Qb. The first region Qa is a region surrounded by a circle Sa having a radius of 0.2R at the center C. The second region Qb is a region between the circle Sa and the minimum inclusion circle S.
When the average particle size of the plurality of metal particles 18 in the first region Qa is Da and the average particle size of the plurality of metal particles 18 in the second region Qb is Db, Db / Da> 1.5. Yes, more preferably Db / Da> 3.
The upper limit of Db / Da is not particularly limited, but it is preferable that Db / Da ≦ 10 in consideration of the line width of the conductive thin wire 14.

When the conductive thin wire has Db / Da> 1.5, as shown in FIG. 2, the metal particles 18 have a small particle size in the vicinity of the center of the conductive thin wire 14 and in the first region corresponding to 0.2R. In the second region outside the metal particles 18, the particle size of the metal particles 18 is large.
Here, after patterning the conductive thin wire containing the polymer and the metal particles, the metal particles can be grown and the electric resistance can be lowered by performing a plating treatment. However, by increasing the amount of metal, the ratio of the polymer supporting the metal particles is relatively reduced. In this state, the stress applied when the conductive thin wire is bent is concentrated on the polymer. Therefore, if the amount of the polymer is small, the stress cannot be withstood and the conductive thin wire is broken, so that the bendability cannot be maintained. Increasing the amount of polymer in order to maintain bendability increases the electrical resistance accordingly. As described above, there is a trade-off relationship between conductivity and bendability.

However, by forming a layer containing metal particles having a small particle size and performing electroless plating in the post-treatment, the metal particles in the region close to the surface are preferentially grown, and the metal is formed on the surface side and inside of the conductive fine wire. It was found that the particle size of the particles can be different.
By forming a region in which the metal particles having a large particle size exist around the metal particles having a small particle size, the conductivity is enhanced in the region where the metal particles have a large particle size, and the metal particles inside are bent in the region where the metal particles are small. We have succeeded in dispersing the stress that is sometimes applied, and realized both low resistance and bendability, leading to the present invention.
By changing the particle size of the metal particles that ensure conductivity between the center and the outside of the conductive thin wire and setting Db / Da> 1.5, the metal particles with a large particle size in the second region Qb are electrically charged. It is responsible for reducing the resistance, and the metal particles in the first region Qa are responsible for dispersing the stress applied when bending. As a result, a conductive thin wire that achieves both conductivity and bendability can be obtained.
When the conductive thin wire is Db / Da ≦ 1.5, the particle size at the center of the conductive thin wire is relatively large, the resistance to stress applied when bending is small, and the bending property is poor. Further, when the particle size on the outside of the conductive thin wire is relatively small, the amount of the polymer is relatively large, the electric resistance is high, and the conductivity is deteriorated. As described above, it is not possible to achieve both conductivity and bendability.

The ratio of the plurality of metal particles contained in the conductive thin wire 14 is not particularly limited, and is often 55% by volume to 95% by volume, preferably 70% by volume to 90% by volume. When the ratio of the metal particles is within the above range, both conductivity and bendability can be achieved. The proportion of metal particles can be determined as described below.
The average particle size Da of the first region Qa is not particularly limited, and is often 10 nm or more and 200 nm or less, preferably 50 nm or more and 200 nm or less, more preferably 50 nm or more and 100 nm or less, and more preferably 50 nm or more. It is more preferably 70 nm or less. The average particle size Da is the particle size of the metal particles before the plating treatment, and if the average particle size Da of the first region Qa of the conductive thin wire is in the above range, the conductive thin wire can be thinned.
The average particle size Db of the second region Qb is not particularly limited, and is often 50 nm or more and 500 nm or less, preferably 100 nm or more and 300 nm or less, and more preferably 100 nm or more and 200 nm or less.

Next, the first region Qa and the second region Qb in the vertical cross section of the conductive thin line will be described with reference to FIG.
In the present invention, the surface of the conductive film is observed with a scanning electron microscope, one extending conductive thin wire is selected, an arbitrary part of the selected one conductive thin wire is selected, and a vertical cross section Ac. To get. The vertical cross section Ac is observed with a scanning electron microscope, and the minimum inclusion circle S, the first region Qa, the second region Qb, and the average particle size Da, the average particle size Db, and the average particle size Db of the metal particles 18 are observed as follows. Find the proportion of metal particles.

As shown in FIG. 2, a plurality of metal particles 18 are present in the vertical cross section Ac of the conductive thin wire 14.
The minimum inclusion circle S is a circle that includes all of the plurality of metal particles 18 existing in the vertical cross section Ac. By setting the minimum inclusion circle S, the center C of the minimum inclusion circle S and the radius R are specified. A first region Qa having a distance of 0.2 R or less from the center C is set. Then, a second region Qb is set in a region having a distance of more than 0.2R and R or less from the center C of the minimum inclusion circle S. The metal particles 18 in the first region Qa are identified. Among the identified metal particles 18, the sphere-equivalent diameters of 10 particles are calculated in order from the largest particle, and the arithmetic average value of the 10 sphere-equivalent diameters is defined as the average particle size Da.
Also in the second region Qb, the metal particles 18 are specified, the sphere equivalent diameters of 10 particles among the specified metal particles 18 are calculated in order from the largest particles, and the arithmetic average value of the 10 sphere equivalent diameters is calculated. Let the average particle size be Db.
The proportion (volume%) of the metal particles is determined by calculating the area of the metal particle portion and the area of the entire conductive thin line from the observation image of the vertical cross section Ac by the scanning electron microscope. ) Can be obtained.

As a measurement method using the scanning electron microscope described above, first, in order to impart conductivity to the surface of the conductive thin wire, carbon vapor deposition is performed on the surface of the conductive thin wire, and then a scanning electron microscope (Hitachi High Technologies Co., Ltd.) By observing the surface morphology with an S-5200 type SEM manufactured by SEM), the region where the metal exists inside the conductive thin wire can be observed. The observation conditions are the secondary electron mode and the acceleration voltage: 10 kV.
At this time, for observing the vertical cross section of the conductive thin wire, an acceleration voltage at which the contrast between the polymer and the metal particles is obtained is selected with a scanning electron microscope. More specifically, as a method of observing the vertical cross section of the conductive thin wire, after cutting the vertical cross section of the conductive thin wire with a microtome, carbon vapor deposition is performed on the exposed vertical cross section to impart conductivity, and a scanning type is used. Observe the vertical cross section with an electron microscope (S-5200 type SEM manufactured by Hitachi High Technologies Co., Ltd.). At this time, an observation image of the vertical cross section Ac is obtained. The observation conditions are the reflected electron mode and the acceleration voltage: 5 kV.

The conductive thin wire includes a polymer and a plurality of metal particles.
The type of polymer is not particularly limited, and known polymers can be used. Among them, the specific polymer described later is preferable.
The metal particles are a portion that guarantees the conductivity of the conductive thin wire. The metal particles may be discretely present in the polymer, or the metal particles may be aggregated and exist as an agglomerate in the polymer. As metal particles, silver (metal silver), copper (metal copper), gold (metal gold), nickel (metal nickel), palladium (metal palladium), or two of these, in that they have better conductivity. A mixture of seeds or more is preferred, silver, copper, or a mixture thereof is more preferred, and silver is even more preferred. It is preferable that the plurality of metal particles are all composed of silver. By making all the metal particles made of silver, the occurrence of disconnection failure of the conductive thin wire is reduced.
Note that FIG. 2 shows a form in which the metal particles are dispersed in the polymer, but the form is not limited to this form, and if Db / Da> 1.5 is satisfied, the metal becomes a layer and is conductive. It may be in a form dispersed in thin lines.

The line width Wa of the conductive thin wire is preferably 1.0 μm or more and less than 5.0 μm from the viewpoint of the balance between bendability and visibility. Among them, the line width Wa is preferably 2.5 μm or less, and more preferably 2.0 μm or less, from the viewpoint that the conductive thin wire is hard to be visually recognized. The lower limit is not particularly limited, but 0.5 μm or more is preferable, and 1.2 μm or more is more preferable, from the viewpoint of more excellent conductivity of the conductive thin wire.
The thickness T of the conductive thin wire is not particularly limited, but is preferably 0.5 μm or more and 3.0 μm or less, and the thickness T is 1.0 or more and 2.0 μm or less from the viewpoint of the balance between conductivity and bendability. Is more preferable.
For the line width Wa of the above-mentioned conductive thin wire 14, any five points corresponding to the line width of one conductive thin line are selected by using a scanning electron microscope, and an arithmetic average value corresponding to the line width of the five places is selected. Is the line width Wa.
Further, for the thickness T of the above-mentioned conductive thin wire 14, an arbitrary 5 points corresponding to the thickness of one conductive thin wire are selected by using a scanning electron microscope, and arithmetic of the portion corresponding to the thickness of the 5 points is performed. Let the average value be the thickness T.

The line resistance value of the conductive thin wire is preferably less than 200 Ω / mm. Among them, from the viewpoint of operability when used as a touch panel, it is more preferably less than 100 Ω / mm, and further preferably less than 60 Ω / mm.
The linear resistance value is the resistance value measured by the four-ended needle method divided by the distance between the measurement terminals. More specifically, after disconnecting both ends of any one conductive thin wire constituting the mesh pattern from the mesh pattern, four (A, B, C, D) microprobes (Micro Co., Ltd.) A support tungsten probe (0.5 μm in diameter) is brought into contact with the separated conductive thin wire, and an internal probe B is used for the outermost probes A and D using a source meter (KEITHLEY source meter 2400 type general-purpose source meter). A constant current I is applied so that the voltage V between C and C becomes 5 mV, the resistance value Ri = V / I is measured, and the obtained resistance value Ri is divided by the distance between B and C to obtain the linear resistance value. ..

The conductive thin wire may form a predetermined pattern, for example, the pattern is not particularly limited, and a triangle such as a regular triangle, an isosceles triangle, a right triangle, a square, a rectangle, a rhombus, a parallelogram, a trapezoid, etc. It is preferable that the geometrical figure is a combination of (regular) n-sided triangles such as (regular) hexagons, (regular) octagons, circles, ellipses, and stars, and is in the form of a mesh (mesh pattern). More preferably.
As shown in FIG. 3, the mesh shape is intended to be a shape including a plurality of openings (lattices) 20 composed of intersecting conductive thin wires 14B. In FIG. 3, the opening 20 has a rhombus (square) shape, but may have another shape. For example, it may be a polygon (for example, a triangle, a quadrangle, a hexagon, and a random polygon). Further, the shape of one side may be a curved shape or an arc shape in addition to a straight line shape. In the case of arcuate shape, for example, the two opposing sides may have an arcuate shape that is convex outward, and the other two opposite sides may have an arcuate shape that is convex inward. Further, the shape of each side may be a wavy line shape in which an arc convex outward and an arc convex inward are continuous. Of course, the shape of each side may be a sine curve.
Here, FIG. 3 is a plan view showing an example of a mesh pattern formed by conductive thin lines of the conductive film according to the embodiment of the present invention.

The length L of one side of the opening 20 is not particularly limited, but is preferably 1500 μm or less, more preferably 1300 μm or less, further preferably 1000 μm or less, preferably 5 μm or more, more preferably 30 μm or more, and further preferably 80 μm or more. preferable. When the length of the side of the opening is within the above range, it is possible to maintain good transparency, and when the conductive film is attached to the front surface of the display device, the display can be visually recognized without discomfort. be able to.
From the viewpoint of visible light transmittance, the aperture ratio of the mesh pattern is preferably 90.00% or more, more preferably 95.00% or more, still more preferably 99.50% or more. The upper limit is not particularly limited, but may be less than 100%.
The aperture ratio corresponds to the ratio of the region on the flexible base material excluding the region having the conductive fine wire in the mesh pattern region to the whole.

<Manufacturing method of conductive film>
Next, a method for producing the conductive film will be described.
The method for producing the conductive film is not particularly limited as long as the conductive film having the above-described configuration can be produced, but a method for producing a conductive substrate having steps A to E described later in this order is preferable in terms of excellent productivity. Hereinafter, each step will be described in detail.

<Step A>
In step A, a silver halide-containing photosensitive layer (hereinafter, “specific polymer”) containing silver halide, gelatin, and a polymer different from gelatin (hereinafter, also referred to as “specific polymer”) is contained on a flexible substrate. This is a step of forming a "photosensitive layer"). By this step, a flexible base material with a photosensitive layer to be subjected to an exposure treatment described later is produced.
First, the materials and members used in step A will be described in detail, and then the procedure of step A will be described in detail.

(Flexible base material)
The flexible base material means a base material that can be bent, and specifically, a base material that does not crack even when bent with a bending radius of curvature of 2 mm. The flexible substrate has workability capable of forming a three-dimensional shape.
The type of the flexible substrate is not particularly limited as long as it can support the photosensitive layer and the conductive thin wire, and examples thereof include a plastic substrate, a glass substrate, and a metal substrate, and a plastic substrate is preferable.
The thickness of the flexible base material is not particularly limited, and is often 25 to 500 μm. When the surface of the flexible base material is used as the touch surface when the conductive film is applied to the touch panel, the thickness of the flexible base material may exceed 500 μm.

Materials constituting the flexible substrate include polyethylene terephthalate (PET) (258 ° C.), polycycloolefin (134 ° C.), polycarbonate (250 ° C.), acrylic film (128 ° C.), and polyethylene naphthalate (269 ° C.). , Polyethylene (135 ° C), polypropylene (163 ° C), polystyrene (230 ° C), polyvinyl chloride (180 ° C), polyvinylidene chloride (212 ° C), and triacetyl cellulose (290 ° C) have a melting point of about 290. A resin having a temperature of ° C. or lower is preferable, and PET, polycycloolefin, and polycarbonate are more preferable. Among these, PET is most preferable because it has excellent adhesion to the conductive thin wire. The value in parentheses is the melting point or the glass transition temperature.
The total light transmittance of the flexible substrate is preferably 85 to 100%. The total light transmittance is measured using "Plastic-How to determine the total light transmittance and the total light reflectance" specified in JIS (Japanese Industrial Standards) K 7375: 2008.

An undercoat layer may be arranged on the surface of the flexible substrate.
The undercoat layer preferably contains a specific polymer described later. When this undercoat layer is used, the adhesion of the conductive thin wire described later to the flexible substrate is further improved.
The method for forming the undercoat layer is not particularly limited, and examples thereof include a method in which a composition for forming an undercoat layer containing a specific polymer is applied onto a flexible substrate and heat treatment is performed as necessary. The undercoat layer forming composition may contain a solvent, if necessary. The type of the solvent is not particularly limited, and examples thereof include the solvent used in the composition for forming a photosensitive layer described later. Further, as the composition for forming the undercoat layer containing the specific polymer, latex containing the particles of the specific polymer may be used.
The thickness of the undercoat layer is not particularly limited, and 0.02 to 0.3 μm is preferable, and 0.03 to 0.2 μm is more preferable, in that the adhesiveness of the conductive layer to the flexible substrate is more excellent.

(Silver halide)
The halogen atom contained in silver halide may be any of chlorine atom, bromine atom, iodine atom and fluorine atom, and these may be combined. For example, silver halide mainly composed of silver chloride, silver bromide, or silver iodide is preferable, and silver halide mainly composed of silver chloride or silver bromide is more preferable. In addition, silver salt bromide, silver iodide bromide, or silver iodide bromide is also preferably used.
Here, for example, "silver halide mainly composed of silver chloride" refers to silver halide in which the mole fraction of chloride ions in the total halide ions in the silver halide composition is 50% or more. The silver halide mainly composed of silver chloride may contain bromide ion and / or iodide ion in addition to chloride ion.

Silver halide is usually in the form of solid particles, and the average particle size of silver halide is preferably 10 to 1000 nm, more preferably 10 to 200 nm, which is equivalent to a sphere, and has a resistance value of a conductive thin wire in a moist heat environment. 50-150 nm is even more preferred in that the variation is smaller.
The spherical equivalent diameter is the diameter of spherical particles having the same volume.
The "sphere-equivalent diameter" used as the average particle size of the silver halide described above is an average value, and the sphere-equivalent diameters of 100 silver halides are measured and arithmetically averaged.

The shape of the silver halide particles is not particularly limited, and for example, spherical, cubic, flat plate (hexagonal flat plate, triangular flat plate, tetragonal flat plate, etc.), octahedron, tetradecahedron, etc. The shape can be mentioned.

(gelatin)
The type of gelatin is not particularly limited, and examples thereof include lime-treated gelatin and acid-treated gelatin. Further, a hydrolyzate of gelatin, an enzymatic decomposition product of gelatin, and gelatin modified with an amino group and / or a carboxyl group (phthalated gelatin and acetylated gelatin) may be used.

(Polymer different from gelatin)
The photosensitive layer contains a polymer different from gelatin. By including this specific polymer in the photosensitive layer, the strength of the conductive thin wire formed from the photosensitive layer is more excellent.
The type of the specific polymer is not particularly limited as long as it is different from gelatin, and a polymer that decomposes gelatin described later and is not decomposed by a proteolytic enzyme or an oxidizing agent is preferable.
Examples of the specific polymer include hydrophobic polymers (water-insoluble polymers), for example, (meth) acrylic resin, styrene resin, vinyl resin, polyolefin resin, polyester resin, polyurethane resin, etc. Consists of at least one resin selected from the group consisting of polyamide-based resins, polycarbonate-based resins, polydiene-based resins, epoxy-based resins, silicone-based resins, cellulose-based polymers, and chitosan-based polymers, or these resins. Examples thereof include a copolymer composed of a plastic resin.
Further, the specific polymer preferably has a reactive group that reacts with a cross-linking agent described later.
The specific polymer is preferably in the form of particles. That is, the photosensitive layer preferably contains particles of a specific polymer.

As the specific polymer, a polymer (copolymer) represented by the following general formula (1) is preferable.
General formula (1): − (A) _x − (B) _y − (C) _z − (D) _w −
In the general formula (1), A, B, C, and D each represent a repeating unit represented by the following general formulas (A) to (D).

R ¹ represents a methyl group or a halogen atom, and a methyl group, a chlorine atom, or a bromine atom is preferable. p represents an integer of 0 to 2, preferably 0 or 1, more preferably 0.
R ² represents a methyl group or an ethyl group, and a methyl group is preferable.
R ³ represents a hydrogen atom or a methyl group, and a hydrogen atom is preferable. L represents a divalent linking group, and a group represented by the following general formula (2) is preferable.
General formula (2):-(CO-X ¹ ) r-X ^2-
In the general formula (2), X ¹ represents an oxygen atom or −NR ³⁰⁻ . Here, R ³⁰ represents a hydrogen atom, an alkyl group, an aryl group, or an acyl group, and may have a substituent (for example, a halogen atom, a nitro group, and a hydroxyl group), respectively. R ³⁰ includes a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, an n-butyl group, and an n-octyl group), or an acyl group (for example, an acetyl group and an acyl group). Benzoyl group) is preferred. As X ¹ , oxygen atom or −NH− is preferable.
X ² represents an alkylene group, an arylene group, an alkylene arylene group, an arylene alkylene group, or an alkylene arylene alkylene group, and these groups include -O-, -S-, -CO-, -COO-, and -NH. _{-, - SO 2 -, -} N (R 31) -, _{^{or, -N (R 31) SO 2}} - and the like may be inserted in the middle. R ³¹ represents a linear or branched alkyl group having 1 to 6 carbon atoms. X ² includes a dimethylene group, a trimethylene group, a tetramethylene group, an o-phenylene group, an m-phenylene group, a p-phenylene group, -CH ₂ CH ₂ OCOCH ₂ CH _2- , or -CH ₂ CH ₂ OCO ( C ₆ H ₄ )-is preferable.
r represents 0 or 1.
q represents 0 or 1, preferably 0.

R ⁴ represents an alkyl group, an alkenyl group, or an alkynyl group, preferably an alkyl group having 5 to 50 carbon atoms, more preferably an alkyl group having 5 to 30 carbon atoms, and further an alkyl group having 5 to 20 carbon atoms. preferable.
R ⁵ is a hydrogen atom, a methyl group, an ethyl group, a halogen atom, or a -CH ₂ COOR ^6, a hydrogen atom, a methyl group, a halogen atom or a -CH ₂ COOR ⁶ is preferably a hydrogen atom, a methyl group , Or −CH ₂ COOR ⁶ is more preferred, and a hydrogen atom is even more preferred.
R ⁶ represents a hydrogen atom or an alkyl group having 1 to 80 carbon atoms, and may be the same as or different from ^{R 4, and R 6} preferably has 1 to 70 carbon atoms, more preferably 1 to 60 carbon atoms.

In the general formula (1), x, y, z, and w represent the molar ratio of each repeating unit.
x is 3 to 60 mol%, preferably 3 to 50 mol%, more preferably 3 to 40 mol%.
y is 30 to 96 mol%, preferably 35 to 95 mol%, more preferably 40 to 90 mol%.
z is 0.5 to 25 mol%, preferably 0.5 to 20 mol%, and more preferably 1 to 20 mol%.
w is 0.5 to 40 mol%, preferably 0.5 to 30 mol%.
In the general formula (1), x is preferably 3 to 40 mol%, y is 40 to 90 mol%, z is 0.5 to 20 mol%, and w is 0.5 to 10 mol%.

As the polymer represented by the general formula (1), the polymer represented by the following general formula (2) is preferable.

In the general formula (2), x, y, z and w are as defined above.

The polymer represented by the general formula (1) may contain a repeating unit other than the repeating units represented by the above general formulas (A) to (D).
Examples of the monomer for forming other repeating units include acrylic acid esters, methacrylic acid esters, vinyl esters, olefins, crotonic acid esters, itaconic acid diesters, maleic acid diesters, and fumaric acid diesters. Classes, acrylamides, unsaturated carboxylic acids, allyl compounds, vinyl ethers, vinyl ketones, vinyl heterocyclic compounds, glycidyl esters, and unsaturated nitriles. These monomers are also described in paragraphs 0010 to 0022 of Japanese Patent No. 3754745. From the viewpoint of hydrophobicity, acrylic acid esters or methacrylic acid esters are preferable, and hydroxyalkyl methacrylate or hydroxyalkyl acrylate is more preferable.
The polymer represented by the general formula (1) preferably contains a repeating unit represented by the general formula (E).

In the above formula, L _E represents an alkylene group, preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 2 to 6 carbon atoms, more preferably an alkylene group having 2 to 4 carbon atoms.

As the polymer represented by the general formula (1), the polymer represented by the following general formula (3) is particularly preferable.

In the above formula, a1, b1, c1, d1, and e1 represent the molar ratio of each repeating unit, a1 is 3 to 60 (mol%), b1 is 30 to 95 (mol%), and c1 is 0.5. ~ 25 (mol%), d1 represents 0.5-40 (mol%), and e1 represents 1-10 (mol%).
The preferred range of a1 is the same as the preferred range of x described above, the preferred range of b1 is the same as the preferred range of y described above, the preferred range of c1 is the same as the preferred range of z described above, and the preferred range of d1 The preferred range is the same as the preferred range of w described above.
e1 is 1 to 10 mol%, preferably 2 to 9 mol%, more preferably 2 to 8 mol%.

The specific polymer can be synthesized by referring to, for example, Japanese Patent No. 3305459 and Japanese Patent No. 3754745.
The weight average molecular weight of the specific polymer is not particularly limited, and is preferably 1000 to 1000000, more preferably 2000 to 750000, and even more preferably 3000 to 500000.

The photosensitive layer may contain a material other than the above-mentioned materials, if necessary.
Examples thereof include metal compounds belonging to Groups 8 and 9 such as rhodium compounds and iridium compounds used for stabilizing and increasing sensitivity of silver halide. Alternatively, as described in paragraphs 0220 to 0241 of JP-A-2009-004348, antistatic agent, nucleation accelerator, spectroscopic sensitizing dye, surfactant, antifog agent, dural agent, black spot prevention. Agents, redox compounds, monomethine compounds, and dihydroxybenzenes are also included. Furthermore, the photosensitive layer may contain a physical developing nucleus.

Further, the photosensitive layer may contain a cross-linking agent used for cross-linking the above-mentioned specific polymers. By containing the cross-linking agent, cross-linking between the specific polymers proceeds, and the connection between the metallic silver in the conductive layer is maintained even when gelatin is decomposed and removed.

(Procedure of step A)
The method for forming the photosensitive layer containing the above-mentioned components in the step A is not particularly limited, but from the viewpoint of productivity, the composition for forming the photosensitive layer containing silver halide, gelatin and a specific polymer is made flexible. A method of contacting the substrate to form a photosensitive layer on the flexible substrate is preferable.
Hereinafter, the form of the composition for forming a photosensitive layer used in this method will be described in detail, and then the procedure of the process will be described in detail.

(Material contained in the composition for forming a photosensitive layer)
The composition for forming a photosensitive layer contains the above-mentioned silver halide, gelatin, and a specific polymer. If necessary, the specific polymer may be contained in the composition for forming a photosensitive layer in the form of particles.
The composition for forming a photosensitive layer may contain a solvent, if necessary.
Examples of the solvent include water, organic solvents (for example, alcohols, ketones, amides, sulfoxides, esters, and ethers), ionic liquids, and mixed solvents thereof.

The method of contacting the photosensitive layer forming composition with the flexible substrate is not particularly limited, and for example, a method of applying the photosensitive layer forming composition on the flexible substrate and a photosensitive layer. Examples thereof include a method of immersing a flexible substrate in the forming composition.
After the above-mentioned treatment, a drying treatment may be carried out if necessary.

(Silver halide-containing photosensitive layer)
The photosensitive layer formed by the above procedure contains silver halide, gelatin, and a specific polymer.
The content of silver halide in the photosensitive layer is not particularly limited, and is preferably ^{3.0 to 20.0 g / m 2 in terms of silver, preferably 5.0 to 15 in terms of more excellent conductivity of the conductive film.} .0 g / m ² is more preferred.
The silver conversion means that all the silver halide is reduced and converted into the mass of silver produced.
The content of the specific polymer in the photosensitive layer is not particularly limited, and 0.04 to 2.0 g / m ² is preferable, and 0.08 to 0.40 g / m 2 is preferable in that the conductivity of the conductive film is more excellent. m ² is more preferable, and 0.10 to 0.40 g / m ² is even more preferable.

<Process B>
Step B is a step of exposing the photosensitive layer and then developing it to form a fine linear silver-containing layer containing metallic silver, gelatin, and a polymer.

By applying the exposure treatment to the photosensitive layer, a latent image is formed in the exposed region.
The exposure may be carried out in a pattern. For example, in order to obtain a mesh pattern composed of conductive thin lines, which will be described later, an exposure method and a laser beam are scanned through a mask having a mesh-like aperture pattern. Then, a method of exposing in a mesh shape can be mentioned.
The type of light used for exposure is not particularly limited as long as it can form a latent image on silver halide, and examples thereof include visible light, ultraviolet light, and X-ray.

By developing the exposed photosensitive layer, metallic silver is deposited in the exposed region (the region where the latent image is formed).
The method of development processing is not particularly limited, and examples thereof include known methods used for silver halide photographic films, photographic papers, printing plate making films, and emulsion masks for photomasks.
In the developing process, a developing solution is usually used. The type of developer is not particularly limited, and examples thereof include a PQ (phenidone hydroquinone) developer, an MQ (Metol hydroquinone) developer, and a MAA (methol ascorbic acid) developer.

This step may further include a fixing process performed for the purpose of removing and stabilizing the unexposed portion of silver halide.
The fixing process is carried out simultaneously with the development and / or after the development. The method of fixing treatment is not particularly limited, and examples thereof include methods used for silver halide photographic films, photographic papers, printing plate making films, and emulsion masks for photomasks.
In the fixing process, a fixing solution is usually used. The type of fixer is not particularly limited, and examples thereof include the fixer described in "Chemistry of Photographs" (written by Sasai, Photograph Industry Publishing Co., Ltd.) p321.

By carrying out the above-mentioned treatment, a fine linear silver-containing layer containing metallic silver, gelatin and a specific polymer is formed.
Examples of the method of adjusting the width of the silver-containing layer include a method of adjusting the opening width of the mask used at the time of exposure. For example, the exposure region can be adjusted by setting the opening width of the mask to 1.0 μm or more and less than 5.0 μm.
Further, when a mask is used at the time of exposure, the width of the formed silver-containing layer can be adjusted by adjusting the exposure amount. For example, when the opening width of the mask is narrower than the target width of the silver-containing layer, the width of the region where the latent image is formed can be adjusted by increasing the exposure amount more than usual. That is, the line width of the conductive thin line can be adjusted by the exposure amount.
Further, when laser light is used, the exposure region can be adjusted by adjusting the focusing range and / or scanning range of the laser light.

The width of the silver-containing layer is preferably 1.0 μm or more and less than 5.0 μm, and more preferably 1.4 μm or less from the viewpoint that the formed conductive thin wire is difficult to see.
The silver-containing layer obtained by the above procedure has a fine line shape, and the width of the silver-containing layer is the length (width) of the silver-containing layer in a direction orthogonal to the direction in which the fine line-shaped silver-containing layer extends. means.

<Process C>
Step C is a step of heat-treating the silver-containing layer obtained in Step B. By carrying out this step, fusion between specific polymers in the silver-containing layer proceeds, and the strength of the silver-containing layer is improved.

The method of heat treatment is not particularly limited, and examples thereof include a method of bringing the silver-containing layer into contact with superheated steam and a method of heating the silver-containing layer with a temperature control device (for example, a heater). The method of contacting with is preferable.

The superheated steam may be superheated steam or a mixture of superheated steam and another gas.
The contact time between the superheated steam and the silver-containing layer is not particularly limited, and is preferably 10 to 70 seconds.
The supply amount of superheated steam is preferably 500 to 600 g / m ³ , and the temperature of superheated steam is preferably 100 to 160 ° C. (preferably 100 to 120 ° C.) at 1 atm.

As the heating conditions in the method of heating the silver-containing layer with the temperature control device, the conditions of heating at 100 to 200 ° C. (preferably 100 to 150 ° C.) for 1 to 240 minutes (preferably 60 to 150 minutes) are preferable.

<Process D>
Step D is a step of removing gelatin in the silver-containing layer obtained in Step C. By carrying out this step, gelatin is removed from the silver-containing layer, and a space is formed in the silver-containing layer.

The method for removing gelatin is not particularly limited, and for example, a method using a proteolytic enzyme (hereinafter, also referred to as “method 1”) and a method for decomposing and removing gelatin using an oxidizing agent (hereinafter, “method 2”). It is also called.).

Examples of the proteolytic enzyme used in Method 1 include enzymes known as plant or animal enzymes capable of hydrolyzing proteins such as gelatin.
Examples of proteolytic enzymes include pepsin, rennin, trypsin, chimotripsin, catepsin, papain, ficin, thrombin, renin, collagenase, bromelain, and bacterial proteases, preferably trypsin, papain, ficin, or bacterial proteases. ..
The procedure in Method 1 may be a method in which the silver-containing layer and the above-mentioned proteolytic enzyme are brought into contact with each other. For example, a treatment solution containing the silver-containing layer and the proteolytic enzyme (hereinafter, also referred to as "enzyme solution"). There is a method of contacting with. Examples of the contact method include a method of immersing the silver-containing layer in the enzyme solution and a method of applying the enzyme solution on the silver-containing layer.
The content of the proteolytic enzyme in the enzyme solution is not particularly limited, and the degree of decomposition and removal of gelatin is easily controlled. 10% by mass is more preferable.
The enzyme solution usually contains water in addition to the above-mentioned proteolytic enzyme.
If necessary, the enzyme solution may contain other additives (for example, pH buffer, antibacterial compound, wetting agent, and retaining agent).
The pH of the enzyme solution is selected so as to maximize the action of the enzyme, but is generally preferably 5 to 9.
The temperature of the enzyme solution is preferably a temperature at which the action of the enzyme is enhanced, specifically 25 to 45 ° C.

If necessary, a washing treatment may be carried out in which the obtained silver-containing layer is washed with warm water after the treatment with the enzyme solution.
The cleaning method is not particularly limited, and a method of bringing the silver-containing layer into contact with hot water is preferable, and examples thereof include a method of immersing the silver-containing layer in warm water and a method of applying hot water on the silver-containing layer.
The temperature of the hot water is appropriately selected depending on the type of proteolytic enzyme used, and is preferably 20 to 80 ° C, more preferably 40 to 60 ° C from the viewpoint of productivity.
The contact time (washing time) between the hot water and the silver-containing layer is not particularly limited, and is preferably 1 to 600 seconds, more preferably 30 to 360 seconds from the viewpoint of productivity.

The oxidizing agent used in Method 2 may be any oxidizing agent capable of decomposing gelatin, and an oxidizing agent having a standard electrode potential of + 1.5 V or more is preferable. Here, the standard electrode potential is intended to be the standard electrode potential (25 ° C., E0) with respect to the standard hydrogen electrode in the aqueous solution of the oxidizing agent.
Examples of the above-mentioned oxidizing agent include persulfuric acid, percarbonic acid, perphosphoric acid, hypochloric acid, peracetic acid, metachloroperbenzoic acid, hydrogen peroxide solution, perchloric acid, periodic acid, potassium permanganate, and the like. Examples thereof include ammonium persulfate, ozone, hypochloric acid or a salt thereof, and hydrogen peroxide solution (standard electrode potential: 1.76 V), hypochloric acid or a salt thereof is preferable from the viewpoint of productivity and economy. , Sodium hypochlorite is more preferred.

The procedure in Method 2 may be a method in which the silver-containing layer is brought into contact with the above-mentioned oxidizing agent, and for example, a treatment liquid containing the silver-containing layer and the oxidizing agent (hereinafter, also referred to as “oxidizing agent liquid”). There is a method of contacting. Examples of the contact method include a method of immersing the silver-containing layer in the oxidizing agent solution and a method of applying the oxidizing agent solution on the silver-containing layer.
The type of solvent contained in the oxidizing agent solution is not particularly limited, and examples thereof include water and organic solvents.

<Step E>
The step E is a step of plating the silver-containing layer obtained in the step D to obtain a conductive thin wire. By carrying out this step, a conductive thin wire filled with a metal (plated metal) is formed in the space formed by removing gelatin.

The type of plating treatment is not particularly limited, and examples thereof include electroless plating (chemical reduction plating or replacement plating) and electrolytic plating, and electroless plating is preferable. As the electroless plating, a known electroless plating technique is used.
Examples of the plating treatment include silver plating treatment, copper plating treatment, nickel plating treatment, and cobalt plating treatment, and silver plating treatment or copper plating treatment is preferable in that the conductivity of the conductive thin wire is more excellent. Silver plating is more preferred.

The components contained in the plating solution used in the plating treatment are not particularly limited, but usually, in addition to the solvent (for example, water), 1. Metal ions for plating, 2. Reducing agent, 3. 4. Additives (stabilizers) that improve the stability of metal ions. It mainly contains a pH regulator. In addition to these, the plating bath may contain known additives such as stabilizers for the plating bath.
The type of metal ion for plating contained in the plating solution can be appropriately selected according to the type of metal to be precipitated, and examples thereof include silver ion, copper ion, nickel ion, and cobalt ion.

The procedure of the plating treatment described above is not particularly limited as long as it is a method of bringing the silver-containing layer into contact with the plating solution, and examples thereof include a method of immersing the silver-containing layer in the plating solution.
The contact time between the silver-containing layer and the plating solution is not particularly limited, and is preferably 1 to 30 minutes from the viewpoint of more excellent conductivity and productivity of the conductive thin wire.
By lengthening the plating treatment time, the outer metal particles grow, the average particle size of the metal particles in the second region can be increased, and the volume% of the metal particles can be increased. In the plating process, the metal particles in the first region do not grow, and the size of the metal particles remains the same as before plating. By adjusting the plating treatment time, the value of Qb / Qa, the average particle size of the metal particles in the second region, and the ratio of the metal particles can be controlled.

<Process F>
The method for producing a conductive film of the present invention may include a step F in which the conductive thin wire obtained in the step E is further smoothed after the step E.
By carrying out this step, a conductive thin wire having more excellent conductivity can be obtained.

The method of smoothing treatment is not particularly limited, and for example, a calendar treatment step in which a flexible base material having conductive thin wires is passed between at least a pair of rolls under pressure is preferable. Hereinafter, the smoothing process using the calendar roll will be referred to as a calendar process.
Examples of the roll used for the calendering process include a plastic roll and a metal roll, and the plastic roll is preferable from the viewpoint of preventing wrinkles.
The pressure between the rolls is not particularly limited, and is preferably 2 MPa or more, more preferably 4 MPa or more, and preferably 120 MPa or less. The pressure between the rolls can be measured using a prescale (for high pressure) manufactured by FUJIFILM Corporation.
The temperature of the smoothing treatment is not particularly limited, and is preferably 10 to 100 ° C, more preferably 10 to 50 ° C.

<Process G>
The method for producing a conductive film of the present invention may further include a step G of heat-treating the conductive thin wire obtained in the step F after the step F. By carrying out this step, a conductive thin wire having more excellent conductivity can be obtained.
The method of heat-treating the conductive thin wire is not particularly limited, and the method described in step C can be mentioned.

<Process H>
The method for producing a conductive film of the present invention may include a step H of forming a silver halide-free layer containing gelatin and a specific polymer on a flexible substrate before the step A. By carrying out this step, a silver halide-free layer is formed between the flexible base material and the silver halide-containing photosensitive layer. This silver halide-free layer serves as a so-called antihalation layer and contributes to improving the adhesion between the conductive layer and the flexible base material.
The silver halide-free layer contains the above-mentioned gelatin and a specific polymer. On the other hand, the silver halide-free layer does not contain silver halide.
The ratio of the mass of the specific polymer to the mass of the gelatin in the silver halide-free layer (mass of the specific polymer / mass of gelatin) is not particularly limited, and is preferably 0.1 to 5.0. 0 to 3.0 is more preferable.
The content of the specific polymer in the silver halide-free layer is not particularly limited, and ^{is often 0.03 g / m 2 or more, and 1.0 g / m 2} in that the adhesiveness of the conductive thin wire is more excellent. The above is preferable. The upper limit is not particularly limited, but it is often ^{1.63 g / m 2 or less.}

The method for forming the silver halide-free layer is not particularly limited. For example, a layer-forming composition containing gelatin and a specific polymer is applied onto a flexible base material, and heat treatment is performed as necessary. There is a method of applying.
The layer-forming composition may contain a solvent, if necessary. Examples of the type of solvent include the solvent used in the above-mentioned composition for forming a photosensitive layer.
The thickness of the silver halide-free layer is not particularly limited, and is often 0.05 μm or more, and is preferably more than 1.0 μm, more preferably 1.5 μm or more, in that the adhesiveness of the conductive thin wire is more excellent. The upper limit is not particularly limited, but is preferably less than 3.0 μm.

<Step I>
The method for producing a conductive film of the present invention includes a step I of forming a protective layer containing gelatin and a specific polymer on a silver halide-containing photosensitive layer after the step A and before the step B. You may. By providing the protective layer, it is possible to prevent scratches on the photosensitive layer and improve the mechanical properties.
The ratio of the mass of the specific polymer to the mass of the gelatin in the protective layer (mass of the specific polymer / mass of gelatin) is not particularly limited, and is preferably more than 0 and 2.0 or less, and more than 0 and 1.0 or less. More preferable.
The content of the specific polymer in the protective layer is not particularly limited but is preferably 0 g / m ² Ultra 0.3 g / m ² or less, and more preferably 0.005~0.1g / m ^2.

The method for forming the protective layer is not particularly limited. For example, a method in which a composition for forming a protective layer containing gelatin and a specific polymer is applied onto a silver halide-containing photosensitive layer and heat-treated as necessary. Can be mentioned.
The composition for forming a protective layer may contain a solvent, if necessary. Examples of the type of solvent include the solvent used in the above-mentioned composition for forming a photosensitive layer.
The thickness of the protective layer is not particularly limited, and is preferably 0.03 to 0.3 μm, more preferably 0.075 to 0.20 μm.

In addition, the above-mentioned step H, step A and step I may be carried out at the same time by simultaneous layer coating.

<Use>
The conductive film obtained as described above can be applied to various uses, such as a touch panel (or touch panel sensor), a semiconductor chip, various electric wiring boards, FPC (Flexible Printed Circuits), COF (Chip on Film), and the like. It can be applied to various applications such as TAB (Tape Automated Bonding), antennas, multilayer wiring boards, and motherboards. Among them, the conductive film of the present invention is preferably used for a touch panel (capacitive touch panel).
When the conductive film of the present invention is used for a touch panel, the above-mentioned conductive thin wire can effectively function as a detection electrode.
The conductive film may have a conductive portion having a structure different from that of the conductive thin wire, in addition to the conductive thin wire having the above-mentioned predetermined characteristics. This conductive portion may be electrically connected to the above-mentioned conductive thin wire to be conductive.

The present invention is basically configured as described above. Although the conductive film of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various improvements or changes may be made without departing from the gist of the present invention. Is.

The features of the present invention will be described in more detail with reference to Examples below. The materials, reagents, amounts of substances and their ratios, operations, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following examples.
In this example, conductivity, bendability, and visibility were evaluated as evaluation items for Examples 1 to 8 and Comparative Examples 1 to 3. Hereinafter, Examples 1 to 8 and Comparative Examples 1 to 3 will be described.

<Example 1>
(Preparation of silver halide emulsion)
To the following liquid 1 kept at 38 ° C. and pH 4.5, an amount corresponding to 90% of each of the following liquids 2 and 3 was added simultaneously for 20 minutes while stirring the 1 liquid, and 0.16 μm nuclei particles were added. Was formed. Subsequently, the following 4 and 5 solutions were added to the obtained solution over 8 minutes, and the remaining 10% of the following 2 and 3 solutions were added over 2 minutes to grow the nuclear particles to 0.21 μm. I let you. Further, 0.15 g of potassium iodide was added to the obtained solution, and the mixture was aged for 5 minutes to complete particle formation.

Liquid 1:
750 ml of water
Gelatin 8.6g
Sodium chloride 3g
1,3-Dimethylimidazolidine-2-thione 20 mg
Sodium benzenethiosulfonate 10 mg
Citric acid 0.7g
Liquid 2:
300 ml of water
Silver nitrate 150g
Liquid 3:
300 ml of water
Sodium chloride 38g
Potassium bromide 32g
Potassium hexachloroiridium (III) (0.005% KCl 20% aqueous solution) 5 ml
Ammonium hexachlororodium acid
(0.001% NaCl 20% aqueous solution) 7 ml
Liquid 4:
100 ml of water
Silver nitrate 50g
Liquid 5:
100 ml of water
Sodium chloride 13g
Potassium bromide 11g
Yellow blood salt 5 mg

Then, it was washed with water by the floculation method according to a conventional method. Specifically, the temperature of the above-mentioned obtained solution was lowered to 35 ° C., and the pH was lowered using sulfuric acid until the silver halide settled (pH was in the range of 3.6 ± 0.2). Next, about 3 liters of the supernatant was removed from the obtained solution (first washing with water). Next, 3 liters of distilled water was added to the solution from which the supernatant had been removed, and then sulfuric acid was added until the silver halide settled. Again, 3 liters of the supernatant was removed from the obtained solution (second wash). The same operation as the second water washing was repeated once more (third water washing), and the water washing and desalting steps were completed. After washing with water and desalting, the emulsion was adjusted to pH 6.4 and pAg 7.5, and gelatin 2.5 g, sodium benzenethiosulfonate 10 mg, sodium benzenethiosulfinate 3 mg, sodium thiosulfate 15 mg and gold chloride acid 10 mg were added. Chemical sensitization was performed at 55 ° C. to obtain optimum sensitivity. Then, 100 mg of 1,3,3a, 7-tetraazaindene as a stabilizer and 100 mg of Proxel (trade name, manufactured by ICI Co., Ltd.) as a preservative were further added to the obtained emulsion. The finally obtained emulsion contains 0.08 mol% of silver iodide, and the ratio of silver bromide is 70 mol% of silver chloride and 30 mol% of silver bromide, and the average particle size (sphere equivalent diameter). It was a silver chloride cubic particle emulsion having a variation coefficient of 9% at 200 nm.

(Preparation of composition for forming a photosensitive layer)
1,3,3a of the above emulsion, 7-tetraazaindene (1.2 × 10 ^-4 mol / mol Ag), hydroquinone (1.2 × 10 ^-2 mol / mol Ag), citric acid (3.0 × 10 ^-4 mol / mol Ag), 2,4-dichloro-6-hydroxy-1,3,5-triazine sodium salt (0.90 g / mol Ag), and a small amount of dural agent were added to compose the composition. I got something. The pH of the composition was then adjusted to 5.6 with citric acid.
In the above composition, a dispersion consisting of a polymer represented by the following (P-1) (hereinafter, also referred to as “polymer 1”) and a dialkylphenyl PEO (PEO is an abbreviation for polyethylene oxide) sulfate ester. The polymer latex containing the agent and water (the ratio of the mass of the dispersant to the mass of the polymer 1 (mass of the dispersant / mass of the polymer 1, the unit is g / g) is 0.02, and the solid content The content is 22% by mass.), The ratio of the mass of the polymer 1 to the total mass of the gelatin in the composition (mass of the polymer 1 / mass of the gelatin, unit g / g) is 0.25 /. The composition was added so as to be 1, and a polymer latex-containing composition was obtained. Here, in the polymer latex-containing composition, the ratio of the mass of gelatin to the mass of silver derived from silver halide (mass of gelatin / mass of silver derived from silver halide, the unit is g / g) is 0. It was 11.
Further, EPOXY RESIN DY 022 (trade name: manufactured by Nagase ChemteX Corporation) was added as a cross-linking agent. The amount of the cross-linking agent added was adjusted so that the amount of the cross-linking agent in the silver halide-containing photosensitive layer described later was 0.09 g / m ^2.
The composition for forming a photosensitive layer was prepared as described above.
The polymer 1 was synthesized with reference to Japanese Patent No. 3305459 and Japanese Patent No. 3754745.

The above-mentioned polymer latex was applied to a polyethylene terephthalate film having a thickness of 40 μm (“a long roll-shaped film manufactured by FUJIFILM Corporation”) to provide an undercoat layer having a thickness of 0.05 μm. This process was performed roll-to-roll, and each of the following processes (steps) was also performed roll-to-roll in the same manner. The roll width at this time was 1 m, and the length was 1000 m.

(Process H1, Process A1, Process I1)
Next, on the undercoat layer, the composition for forming a silver halide-free layer in which the above-mentioned polymer latex and gelatin are mixed, the above-mentioned composition for forming a photosensitive layer, and the protection in which the above-mentioned polymer latex and gelatin are mixed are mixed. The layer-forming composition was simultaneously applied in multiple layers to form a silver halide-free layer, a silver halide-containing photosensitive layer, and a protective layer on the undercoat layer.
The thickness of the silver halide-free layer is 2.0 μm, and the mixed mass ratio of polymer 1 and gelatin (polymer 1 / gelatin) in the silver halide-free layer is 2/1, which is high. The content of molecule 1 was 1.3 g / m ² .
The thickness of the silver halide-containing photosensitive layer is 2.5 μm, and the mixed mass ratio of polymer 1 and gelatin (polymer 1 / gelatin) in the silver halide-containing photosensitive layer is 0.25 / 1. The content of the polymer 1 was 0.19 g / m ² .
The thickness of the protective layer is 0.15 μm, the mixed mass ratio of polymer 1 and gelatin (polymer 1 / gelatin) in the protective layer is 0.1 / 1, and the content of polymer 1 is It was 0.015 g / m ^2.

(Step B1)
The prepared photosensitive layer was exposed to light through a grid-like photomask using parallel light using a high-pressure mercury lamp as a light source. A mask for pattern formation is used as the photomask, and the line width of the unit square grid forming the grid as shown in FIG. 3 is 1.2 μm, and the length L of one side of the grid (opening) is 600 μm. I did.
After exposure, the obtained sample is developed with a developing solution described later, further developed with a fixing solution (trade name: N3X-R for CN16X: manufactured by FUJIFILM Corporation), and then at 25 ° C. Was rinsed with pure water and then dried to obtain Sample A having a silver-containing layer containing metallic silver formed in a mesh pattern. In sample A, a conductive mesh pattern region having a size of 21.0 cm × 29.7 cm was formed.

(Composition of developer)
The following compounds are contained in 1 liter (L) of the developing solution.
Hydroquinone 0.037 mol / L
N-Methylaminophenol 0.016 mol / L
Sodium metaborate 0.140 mol / L
Sodium hydroxide 0.360 mol / L
Sodium bromide 0.031 mol / L
Potassium metabisulfate 0.187 mol / L

The obtained sample A was immersed in warm water at 50 ° C. for 180 seconds. After that, the water was drained with an air shower and allowed to air dry.
(Process C1)
The sample A obtained in step B1 was carried into a superheated steam treatment tank at 110 ° C. and allowed to stand for 30 seconds to perform superheated steam treatment. The steam flow rate at this time was 100 kg / h.
(Step D1)
The sample A obtained in step C1 was immersed in a hypochlorous acid-containing aqueous solution (25 ° C.) for 30 seconds. Sample A was taken out from the aqueous solution, and sample A was immersed in warm water (liquid temperature: 50 ° C.) for 120 seconds for washing. After that, the water was drained with an air shower and allowed to air dry.
The hypochlorous acid-containing aqueous solution used was prepared by diluting a highter manufactured by Kao Corporation twice and then using it.

(Step E1)
The sample A obtained in step D1 was immersed in a plating solution A (30 ° C.) having the following composition for 5 minutes. Sample A was taken out from the plating solution A, and the sample A was immersed in warm water (liquid temperature: 50 ° C.) for 120 seconds for washing.
The composition of the plating solution A (total volume 1200 ml) was as follows. The pH of the plating solution A was 9.5, and the pH was adjusted by adding a predetermined amount of potassium carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The following ingredients used were all manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. No change in line width was observed before and after the plating process.

(Composition of plating solution A)
・ AgNO ₃ 8.8g
・ Sodium sulfite 72g
・ Sodium thiosulfate pentahydrate 66g
・ Potassium iodide 0.004g
・ Citric acid 12g
・ Methyl hydroquinone 3.67g
・ Potassium carbonate Prescribed amount ・ Water balance

(Step F1)
The sample A obtained in step E1 was calendar-processed at a pressure of 30 kN using a calendar device using a combination of a metal roller and a resin roller. Calendering was performed at room temperature.
(Process G1)
The sample A obtained in step F1 was carried into a superheated steam treatment tank at 110 ° C. and allowed to stand for 30 seconds to perform superheated steam treatment. The steam flow rate at this time was 100 kg / h. The obtained conductive mesh pattern region was a mesh-like layer of a unit square lattice formed from conductive thin lines as shown in FIG. The line width of the conductive thin wire was 3.0 μm, and the thickness of the conductive thin wire was 1.3 μm.

The cross section of the obtained sample A was cut with a microtome, carbon vapor deposition was performed, and then observation was performed using an S-5200 type SEM manufactured by Hitachi High-Technologies Corporation. The observation mode was a reflected electron mode, and the acceleration voltage was 5 kV.
In each region of the obtained cross-sectional photograph, the sphere equivalent diameters of 10 particles are calculated in order from the largest particle, and the average particle diameter Da of the metal particles contained in the first region Qa and the second The average particle size Db of the metal particles contained in the region Qb was determined. When Db / Da was calculated, Db / Da = 2.0.

<Examples 2 to 8 and Comparative Examples 1 to 3>
In Examples 2 to 8 and Comparative Examples 1 to 3, the exposure amount was changed by adjusting the exposure time in step B1, and the line width was adjusted.
The "line width" shown in Table 1 was measured after the heated steam treatment in step G1, and a microscope VHX-5000 manufactured by KEYENCE CORPORATION was used for the measurement of the line width. In addition, the silver particle size after fusion by the heated steam treatment in step G1 was adjusted by adjusting the exposure amount.
By lengthening the plating treatment time in step E1, the outer particles grow and the volume% of the metal particles also increases. Therefore, the line width, Db / Da, and metal particles are adjusted by adjusting the exposure amount and plating treatment time in step B1. The body integration rate of was adjusted.

In Example 5, electroless copper plating was performed during the plating treatment in step E1. A commercially available electroless copper plating solution can be used as the electroless copper plating solution, and in the production of Example 5, "OIC Axela" and "OIC Copper" manufactured by Okuno Pharmaceutical Industry Co., Ltd. are used, and OIC Axela (OIC Axela) ( It was immersed in OIC copper (55 ° C.) for 3 minutes at 25 ° C.) and then rinsed with pure water at 25 ° C. The other steps were prepared in the same manner as in other examples.
In Comparative Example 1, the exposure amount was changed by adjusting the exposure time in step B1 so that Db / Da = 1.
In Comparative Example 2, a glass base material was used. In Comparative Example 3, the conductive thin wire did not contain a polymer.

<Evaluation>
Hereinafter, the evaluation items of conductivity, bendability, and visibility will be described.
(Conductivity)
The conductivity was evaluated by measuring the linear resistance value of the conductive mesh pattern region of the obtained conductive film. The linear resistance value is the resistance value measured by the four-ended needle method divided by the distance between the measurement terminals. More specifically, after disconnecting both ends of any one conductive thin wire constituting the mesh pattern from the mesh pattern, four (A, B, C, D) microprobes (Micro Co., Ltd.) The support tungsten probe (diameter 0.5 μm)) is brought into contact with the separated conductive thin wire, and the outermost probes A and D are separated by 250 μm using a source meter (KEITHLEY source meter, 2400 type general-purpose source meter). A constant current I is applied so that the voltage V between the internal probes B and C is 5 mV, the resistance value Ri = V / I is measured, and the obtained resistance value Ri is divided by the distance between B and C to form a line. The resistance value was calculated. The obtained resistance value Ri was divided by the distance between B and C to obtain a linear resistance value, and the average value of the measured values at any 10 points was evaluated as conductivity according to the following criteria. In the evaluation of conductivity, among the following 1 to 5, 3 or more is preferable, 4 or more is more preferable, and 5 is further preferable.
5: The line resistance value is less than 60 Ω / mm.
4: The line resistance value is 60 Ω / mm or more and less than 80 Ω / mm.
3: The line resistance value is 80 Ω / mm or more and less than 100 Ω / mm.
2: The line resistance value is 100 Ω / mm or more and less than 200 Ω / mm.
1: The line resistance value is 200Ω / mm or more.

(Bendability)
Regarding the bendability, the obtained conductive film was bent multiple times with a bending tester in a direction in which the angle between the direction DL (see FIG. 1) in which the conductive thin wire extends and the bending direction is 45 °. The change in conductivity was measured and evaluated. For the bending test, a small desktop tester TCDM111LH manufactured by Yuasa System Co., Ltd. was used. The bending radius was set to 2 mm, and the evaluation was made according to the following criteria based on the resistance change δ after bending 200,000 times. The resistance change δ is represented by resistance change δ = (resistance value after the bending test) / (resistance value before the bending test).
The "resistance value" here refers to the resistance value Ri obtained by the above-mentioned conductivity evaluation. In the evaluation of the bendability, 3 or more are preferable, 4 or more is more preferable, and 5 is further preferable among the following 1 to 5.
5: δ is less than 1.1.
4: δ is 1.1 or more and less than 1.15.
3: δ is 1.15 or more and less than 1.2.
2: δ is 1.2 or more and less than 1.5.
1: δ is 1.5 or more, or the conductive thin wire is broken.

(Visibility)
The obtained conductive films are laminated in the order of glass / conductive film / polarizing plate / polarizing plate (direction in which the polarizing surface is orthogonal) / black PET (manufactured by Panac Co., Ltd., industrial black PET (GPH100E82A04)). , A laminate was obtained. In the conductive film, the conductive film was arranged so that the conductive mesh pattern was located on the glass side.
Next, 10 observers visually observed the obtained laminate with 500 lux ambient light from the front surface on the glass surface side and an angle of 30 ° to 60 °, and according to the following criteria. , Visibility was evaluated. When the mesh pattern is difficult to see, the optical characteristics are excellent, and moire generated when the conductive film is laminated on the display is reduced. In the evaluation of visibility, among the following 1 to 5, 3 or more is preferable, 4 or more is more preferable, and 5 is further preferable.
When the conductive film was observed from a distance of 5:15 cm, the mesh pattern was not visually recognized.
When observing the conductive film from a position 4:30 cm away, there were 0 or 1 observers who visually recognized the mesh pattern.
When observing the conductive film from a position 3:30 cm away, there were 2 to 4 observers who visually recognized the mesh pattern.
When observing the conductive film from a position 2:30 cm away, there were five or more observers who visually recognized the mesh pattern.
When observing the conductive film from a position 1:50 cm away, there were five or more observers who visually recognized the mesh pattern.

As shown in Table 1, in Examples 1 to 8, better results can be obtained in terms of conductivity, bendability and visibility as compared with Comparative Examples 1 to 3, and both conductivity and bendability can be achieved at the same time. I was able to realize it.
In Comparative Example 1, Db / Da = 1, the conductivity was inferior, and both conductivity and bendability could not be realized.
Comparative Example 2 was a glass base material, which was inferior in bendability, and could not achieve both conductivity and bendability.
In Comparative Example 3, the conductive thin wire did not contain a polymer and was inferior in bendability, so that both conductivity and bendability could not be realized.
In Examples 1 to 8, the value of Db / Da is high (Db / Da> 3), the volume fraction is high (70% by volume to 90% by volume), and the average particle size Da is large (50 nm or more and 200 nm or less). , Example 8 gave the best results.
From Examples 1 to 8, when the line width of the conductive thin wire was 2.5 μm or less (preferably 2.0 μm or less), the visibility was more excellent.
In Example 1 and Example 5 in which the line width and thickness of the conductive thin wire are the same, the silver-plated Example 1 was superior in bendability.

10 Conductive film 12 Flexible base material 12a Surface 14, 14B Conductive wire 14a Surface 16 Polymer 18 Metal particles 20 Opening Ac Vertical cross section DL direction DW direction Qa First area Qb Second area R Radius S Minimum Inclusion Circle Sa Circle T Thickness Wa Line Width

Claims (9)

Flexible substrate and
It has a conductive thin wire containing a plurality of metal particles dispersed in a polymer, which is arranged on the flexible substrate.
In the vertical cross section of the conductive thin wire in a direction orthogonal to the extending direction of the conductive thin wire, the radius of the minimum inclusion circle containing all the plurality of metal particles is R, and the distance from the center of the minimum inclusion circle. A region of 0.2 R or less is defined as a first region, and a region having a distance of more than 0.2 R and R or less from the center of the minimum inclusion circle is defined as a second region.
When the average particle size of the plurality of metal particles in the first region is Da and the average particle size of the plurality of metal particles in the second region is Db, Db / Da> 1.5. Conductive film. The average particle size Da of the plurality of metal particles in the first region and the average particle size Db of the plurality of metal particles in the second region are Db / Da> 3, claim 1. The conductive film according to. The conductive film according to claim 1 or 2, wherein the proportion of the plurality of metal particles contained in the conductive thin wire is 70% by volume to 90% by volume. The conductive film according to any one of claims 1 to 3, wherein the average particle size Da of the plurality of metal particles in the first region is 50 nm or more and 200 nm or less. The conductive film according to any one of claims 1 to 4, wherein the flexible base material is made of polyethylene terephthalate. The conductive film according to any one of claims 1 to 5, wherein the plurality of metal particles contain silver. The conductive film according to any one of claims 1 to 6, wherein the plurality of metal particles are all made of silver. The conductive film according to any one of claims 1 to 7, wherein the line width of the conductive thin wire is 1.0 μm or more and less than 5.0 μm. The conductive film according to any one of claims 1 to 8, wherein the thickness of the conductive thin wire is 0.5 μm or more and less than 3.0 μm.

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