Dispersion containing conductive particles, and coating liquid for formation of conductive film

Abstract

To provide conductive particles enabling reduction in resistance of a transparent conductive film.SOLUTION: In a dispersion containing conductive particles, fibrous conductors, and a hydrophilic organic solvent, the weight ratio of the conductive particles to the fibrous conductors (conductive particles / fibrous conductors) is 100 to 1000, the content of the conductive particles is less than 15 wt.%, and the water content is less than 9.5 wt.%. The conductive particles include first conductive particles bound to the fibrous conductors and second conductive particles not bound to the fibrous conductors, and the weight ratio of the second conductive particles to the first conductive particles (second conductive particles / first conductive particles) is 0.5 to 20.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dispersion containing conductive particles and fibrous conductors. [Background technology]

[0002] Conventionally, conductive films are formed on substrates using coating solutions containing conductive particles. Transparent conductive films are used in display devices, touch panels, solar cells, etc. The higher the content of conductive particles, the better the conductivity, but the lower the transparency tends to be. In order to achieve both transparency and low resistance, various improvements have been made to coating solutions containing conductive particles.

[0003] It is known that chain-like conductive particles are used to reduce resistance in order to obtain a film with excellent antistatic and electromagnetic wave shielding properties (see, for example, Patent Document 1). It is also known that carbon nanotubes (CNTs) are added to a coating composition to impart conductivity to an abrasion-resistant coating (film) (see, for example, Patent Document 2). Furthermore, Patent Document 2 adds a filler (metal oxide particles, etc.) to the coating composition to improve the hardness and refractive index of the film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-339113 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-508039 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a strong demand for lower resistance in transparent conductive films, but the chain-like conductive particles disclosed in Patent Document 1 were unable to achieve both low resistance and good transparency. In addition, although the composition of Patent Document 2 contains a mixture of CNTs and metal oxide particles, the metal oxide particles do not contribute much to improving conductivity, and the transparent conductive film was unable to achieve both conductivity and transparency.

[0006] Therefore, an object of the present invention is to provide conductive particles that enable a transparent conductive film to have both low resistance and transparency (low haze). [Means for solving the problem]

[0007] The present inventors have discovered that the conductivity of a coating film can be improved by using a dispersion containing fibrous conductors to which conductive particles are bonded. The dispersion of the present invention contains conductive particles, fibrous conductors, and a hydrophilic organic solvent. The conductive particles include first conductive particles bonded to the fibrous conductors and second conductive particles not bonded to the fibrous conductors. That is, the fibrous conductors to which the first conductive particles are bonded and the second conductive particles are dispersed in the organic solvent. Here, the conductive particle concentration in the dispersion is less than 15% by weight, the weight ratio of the conductive particles (first conductive particles + second conductive particles) to the fibrous conductor [conductive particles / fibrous conductor] is in the range of 100 to 1000, and the weight ratio of the second conductive particles to the first conductive particles (second conductive particles / first conductive particles) is in the range of 0.5 to 20. Furthermore, the water content of the dispersion is less than 9.5% by weight.

[0008] Furthermore, the conductive particle dispersion according to the present invention can be obtained by mixing a dispersion in which conductive particles are dispersed in a hydrophilic organic solvent with a dispersion of fibrous conductors, and then dispersing the mixed solution by applying ultrasonic waves while keeping the liquid temperature below 40° C. In this case, the weight ratio of the conductive particles to the fibrous conductors in the mixed dispersion (conductive particles / fibrous conductors) is set to a range of 100 to 1000. DETAILED DESCRIPTION OF THE INVENTION

[0009] The dispersion of the present invention contains dispersed fibrous conductors having conductive particles bonded thereto and conductive particles not bonded to the fibrous conductors. The weight ratio of the conductive particles to the fibrous conductors (conductive particles / fibrous conductors) is 100 or more and 1000 or less, and the conductive particles contained in the dispersion are less than 15% by weight. If the conductive particles bonded to the fibrous conductors are referred to as first conductive particles and the conductive particles not bonded to the fibrous conductors are referred to as second conductive particles, the weight ratio of the second conductive particles to the first conductive particles (second conductive particles / first conductive particles) is in the range of 0.5 to 20. The water content in the dispersion is less than 9.5% by weight. In such a dispersion, the fibrous conductors having first conductive particles bonded thereto and the second conductive particles are dispersed. Even if the fibrous conductors cannot be dispersed in the solvent (first solvent) in which the conductive particles are dispersed, the fibrous conductors having conductive particles bonded to their surfaces can be dispersed in the first solvent. The upper limit of the weight ratio of the conductive particles to the fibrous conductors is preferably 700 or less. The upper limit of the weight ratio of the second conductive particles to the first conductive particles is preferably 15 or less. Furthermore, the weight ratio of the first conductive particles to the fibrous conductor (weight of first conductive particles / weight of fibrous conductor) is preferably in the range of 15-500, and more preferably in the range of 15-300.

[0010] The concentration of the conductive components (conductive particles + fibrous conductor) in the mixed dispersion is preferably 0.5% by weight or more and less than 14% by weight. The concentration of the fibrous conductor in the mixed dispersion is preferably in the range of 0.001 to 0.1% by weight. If the concentration exceeds 0.1% by weight, the viscosity of the dispersion increases. Also, the transparency of the film may decrease. If the concentration is less than 0.001% by weight, good conductivity may not be obtained.

[0011] The fibrous conductor preferably has a high aspect ratio (length / width). Since the conductive paths formed in the film are longer and more easily connected, good conductivity can be obtained without increasing the amounts of fibrous conductor and conductive particles. Furthermore, nano-sized fibrous conductors are preferred to obtain high transparency. The length of the fibrous conductor is preferably 100 nm to 5000 nm, and the length-to-width (or diameter) ratio (length / width) is preferably 50 to 5000. It is more preferable that the width (or diameter) of the fibrous conductor is in the range of 1.1 nm to 2.0 nm.

[0012] An example of the conductive particles is conductive oxide particles. The average particle diameter of monodispersed conductive particles is preferably 1 to 50 nm. Chain particles may also be used as the conductive particles. Chain particles are particles in which three or more conductive primary particles are connected in a chain shape. Branched and connected portions of the particles may exist. That is, the structure is such that three or more primary particles are connected at the main chain portion, and branched portions may exist. The primary particles are inorganic particles in a monodispersed state. The average particle diameter of the primary particles is preferably 1 to 30 nm. The particle diameters of 100 random primary particles are measured from an image taken with a transmission electron microscope (TEM), and the average value is used as the average particle diameter of the primary particles. Furthermore, 50 random particles are selected from this image, and the number of connections of each particle is measured. The average number of connections of the 50 particles is used as the average number of connections. The average number of connections is preferably 3 or more, and particularly preferably 5 or more. If the average number of connections of the primary particles is low, the effect of improving conductivity may not be sufficiently obtained. If the average particle size is too small, the crystallinity will be low and the primary particles themselves may not have sufficient conductivity. Conversely, if the average particle size is too large, it will be difficult to develop a chain structure, and even if a chain structure is formed, it will be difficult to effectively form a conductive path, and the film may not have sufficient conductivity. When the primary particles are ATO particles, elements other than antimony and tin oxide may be contained to the extent that they do not significantly impair conductivity.

[0013] Next, a method for producing the dispersion of the present invention will be described. A dispersion of conductive particles and a dispersion of fibrous conductor are mixed. At this time, the weight ratio of the conductive particles to the fibrous conductor (conductive particles / fibrous conductor) is in the range of 100 to 1000. Ultrasonic waves are applied to the resulting mixture while the liquid temperature does not exceed 40°C. This results in a dispersion in which the fibrous conductor to which the first conductive particles are bonded and the second conductive particles are dispersed. Here, it is preferable to select a solvent in which fibrous conductors cannot be dispersed as the solvent for the dispersion of the present invention. In such a solvent, the fibrous conductors are in an unstable state, and it is expected that a force will act to stabilize them by bonding with the conductive particles. In other words, an effective conductive path is likely to be formed by bonding between the fibrous conductors and the conductive particles. Furthermore, it is preferable that the solvent for the dispersion of the present invention or the solvent for the dispersion of conductive particles is miscible with the solvent for the dispersion of the fibrous conductor. If they are not mixed, i.e., if a layer is formed without intermixing, there is a risk that a sufficient amount of conductive particles will not be bonded to the fibrous conductor. Furthermore, it is not preferable to add a dispersant so that the fibrous conductors are well dispersed in the dispersion liquid (dispersion medium) of the present invention. When the dispersant adheres to the surface of the fibrous conductors, not only does the surface resistance increase, but the dispersant may peel off from the fibrous conductors during the ultrasonic dispersion process during mixing, causing the fibrous conductors to rapidly aggregate. Once aggregates form, it is difficult to redisperse them into a stable state.

[0014] <Coating liquid> A coating solution is prepared by adding a binder component and a solvent to the dispersion containing the conductive particles. The solvent used here should be removable by a drying process or the like after coating. Hydrophilic organic solvents such as alcohol, glycol, glycol ethers, and ketones are suitable. Specific examples include 1-methoxy-2-bindernol, diacetone alcohol, ethylene glycol, diethylene glycol, methanol, ethanol, isopropyl alcohol, and acetone.

[0015] An example in which single-walled carbon nanotubes (CNTs) are used as fibrous conductors will be described in detail below.

[0016] [Example 1] First, an aqueous dispersion of CNTs and a dispersion of conductive particles were prepared. 0.10 g of a surfactant (polyacrylic acid, molecular weight 25,000, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to 9.86 g of water and stirred for 10 minutes. 0.04 g of CNTs (TUBALL 01RW03, manufactured by OCSiAl Corporation) was added to 9.96 g of this aqueous solution, and the CNTs were dispersed using an ultrasonic disperser (Horne type 5281, manufactured by Kaijo Corporation) to obtain an aqueous dispersion of CNTs. Aqueous dispersions of CNTs can be prepared using known methods (see, for example, JP 2023-004883 A). 10.00 g of this aqueous dispersion of CNTs was mixed with 150.00 g of a dispersion of antimony-doped tin oxide particles (ATO) (particle solids concentration 5.33 wt %, dispersion medium "ethanol", primary particle diameter 20 nm, volume average particle diameter 32 nm).

[0017] This mixed solution was subjected to ultrasonic waves for 30 minutes using the ultrasonic disperser described above. During this time, ultrasonic waves were applied while cooling in a water bath so that the liquid temperature did not exceed 40°C. This resulted in a dispersion (mixed dispersion) in which fibrous conductors bound to ATO particles and ATO particles not bound to the fibrous conductors were dispersed.

[0018] <Preparation of film-coated substrate> The mixed dispersion liquid was applied to a glass substrate using a bar coater so that the wet film thickness was 10 to 50 μm, and dried at 130° C. for 30 minutes to obtain a substrate with a film having a film thickness of about 100 to 200 nm.

[0019] The physical properties of the mixed dispersion and film-coated substrate obtained as described above were measured and evaluated as follows. The preparation conditions of the mixed dispersion are shown in Table 1, and the physical properties of the film-coated substrate (coating film) are shown in Table 2. The same procedures were basically carried out in other examples and comparative examples.

[0020] (1) Content of conductive particles and fibrous conductors The mixed dispersion was heated at 200°C for 3 hours to remove the solvent from the dispersion, yielding a mixture of fibrous conductors and conductive particles. The weight of this mixture was measured. The mixture was then added to a 2% aqueous solution of sodium hypochlorite, which decomposes the fibrous conductors (single-walled CNTs), while adjusting the pH so that the conductive particles would not dissolve. The mixture was then stirred for 100 hours to decompose the fibrous conductors. The liquid was filtered, and the residue on the filter was air-dried and weighed to obtain the weight of the conductive particles. The weight of the fibrous conductors was then calculated from the weight of the mixture and the weight of the conductive particles.

[0021] (2) Weight concentration of the first conductive particles and the second conductive particles 5.0 g of the mixed dispersion was filtered using a PTFE Millex-LS 5.0 μm filter (manufactured by Merck). This resulted in a filtrate from which the fibrous conductors had been removed. In other words, no first conductive particles were present, and only second conductive particles were present. 3.0 g of this filtrate was used as a sample and heated at 200°C for 30 minutes using a heat-drying moisture meter (ML-50 manufactured by A&D Co., Ltd.) to remove the solvent. The solids weight concentration of the second conductive particles was determined from the residue. The solids weight concentration of the first conductive particles was calculated from the obtained solids weight concentration of the second conductive particles.

[0022] (3) Volume average particle size 9.0 g of the conductive particle dispersion medium (ethanol) was added to 1.0 g of the mixed dispersion, and ultrasonic waves were applied for 1 minute using an ultrasonic disperser. The volume average particle diameter of the obtained dispersion was measured using a dynamic light scattering particle size distribution analyzer (MALVERN Zetasizer (registered trademark)).

[0023] (4) Size of the fibrous conductor The minor axis of the single-walled CNT is the diameter of the cylindrical single-walled CNT, and was determined by the following method. Using LabRAM ARAMIS (manufactured by Horiba, Ltd.) and a laser light source of 633 nm, the Raman spectrum of the CNT dispersion was measured. The 100-300 cm range of the obtained Raman spectrum, which is characteristic of single-walled CNT, -1 Maximum peak shift of radial breathing (RBM) mode in the region ω(RBM)(cm -1) the diameter of the CNT was calculated using the formula "diameter (nm) = 248 / ω(RBM)".

[0024] The major axis, i.e., the length, of the single-walled CNTs was determined by the following method: Using a scanning electron microscope (JEOL JSM-7600F) set at a magnification of 100,000 times, the CNTs were observed, and 50 length measurement points were selected at random and measured, and the arithmetic average was taken as the major axis of the CNTs.

[0025] (5) Average particle size of conductive particles The mixed dispersion was photographed using a transmission electron microscope (JEM-2100 manufactured by JEOL Ltd.), and the average particle size was calculated from the arithmetic mean of the diameters of 100 conductive particles.

[0026] (6) Measuring method for surface resistance of film The surface resistance of the film-coated substrate was measured using a surface resistance measuring device (Hirester UX MCP-HT800 manufactured by Nitto Seiko Analytech Co., Ltd.).

[0027] (7) Optical properties of film-coated substrate The total light transmittance and haze were measured using a haze meter (HZ-V3 manufactured by Suga Test Instruments Co., Ltd.).

[0028] (8) Film thickness measurement method A portion of the film surface was peeled off with a cutter, and the film thickness was measured from the step when the boundary between the film and the glass substrate was scanned using a surface roughness measuring device (SURFCOM NEX001-SD012 manufactured by Tokyo Seimitsu Co., Ltd.).

[0029] [Example 2] To 158.00 g of a dispersion of antimony-doped tin oxide particles (particle solid content concentration 2.53 wt %, dispersion medium "ethanol", primary particle diameter 20 nm, volume average particle diameter 32 nm), 2.00 g of the same aqueous dispersion of CNT as in Example 1 was added. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0030] [Example 3] To 158.00 g of a dispersion of antimony-doped tin oxide particles (particle solids concentration 2.53 wt %, dispersion medium "ethanol and water mixture, water content 6.84 wt %, primary particle diameter 20 nm, volume average particle diameter 32 nm) was added 2.00 g of the same aqueous dispersion of CNTs as in Example 1. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0031] [Example 4] To 190.00 g of a dispersion of antimony-doped tin oxide particles (particle solid content concentration 10.53 wt %, dispersion medium "ethanol", primary particle diameter 20 nm, volume average particle diameter 32 nm), 10.00 g of the same aqueous dispersion of CNT as in Example 1 was added. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0032] [Example 5] An aqueous dispersion of CNT was prepared in the same manner as in Example 1, except that polyvinylpyrrolidone K90 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the surfactant.

[0033] 10.00 g of this CNT aqueous dispersion was added to 150.00 g of the same ATO dispersion as in Example 1. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0034] [Example 6] A dispersion of chain particles formed by linking antimony-doped tin oxide particles (primary particles) (particle solids concentration 5.33 wt %, dispersion medium "ethanol", primary particle diameter 8 nm, volume average particle diameter 60 nm) was prepared. The chain particle dispersion can be prepared using a known method such as the method disclosed in JP 2006-339113 A. 10.00 g of the same aqueous dispersion of CNTs as in Example 1 was added to 150.00 g of this chain particle dispersion. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. This produced a mixed dispersion.

[0035] [Example 7] To 158.00 g of a dispersion of chain-like particles formed by linking antimony-doped tin oxide particles (primary particles) (particle solids concentration 2.53 wt %, dispersion medium "ethanol", primary particle diameter 8 nm, volume average particle diameter 60 nm), 2.00 g of the same aqueous dispersion of CNT as in Example 1 was added. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0036] [Example 8] 2.00 g of the same aqueous dispersion of CNT as in Example 1 was added to 158.00 g of a dispersion of chain-like particles formed by linking antimony-doped tin oxide particles (primary particles) (particle solids concentration 2.53 wt %, dispersion medium "ethanol and water mixture, water content 6.84 wt %", primary particle diameter 8 nm, volume average particle diameter 60 nm). Ultrasonic waves were applied to this mixed solution in the same way as in Example 1. As a result, a mixed dispersion was obtained.

[0037] [Example 9] 10.00 g of the same aqueous dispersion of CNT as in Example 1 was added to 190.00 g of a dispersion of chain-like particles formed by linking antimony-doped tin oxide particles (primary particles) (particle solids concentration 10.53 wt %, dispersion medium "ethanol", primary particle diameter 8 nm, volume average particle diameter 60 nm). Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0038] [Example 10] To 150.00 g of a dispersion of chain-like particles formed by linking antimony-doped tin oxide particles (primary particles) (particle solid content concentration 5.33 wt %, dispersion medium "ethanol", primary particle diameter 8 nm, volume average particle diameter 60 nm), 10.00 g of the same aqueous dispersion of CNT as in Example 5 was added. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0039] [Example 11] To 150.00 g of a dispersion of antimony particles (particle solid content concentration 5.33 wt %, dispersion medium "methanol", primary particle diameter 20 nm, volume average particle diameter 30 nm), 10.00 g of the same aqueous dispersion of CNT as in Example 1 was added. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0040] [Example 12] To 156.00 g of a dispersion of antimony particles (particle solid content concentration 1.03 wt %, dispersion medium "1-methoxy-2-propanol", primary particle diameter 20 nm, volume average particle diameter 30 nm), 4.00 g of the same aqueous dispersion of CNT as in Example 1 was added. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0041] [Example 13] To 150.00 g of a dispersion of antimony particles (particle solid content concentration 5.33 wt %, dispersion medium "2-propanol", primary particle diameter 20 nm, volume average particle diameter 30 nm), 10.00 g of the same aqueous dispersion of CNT as in Example 1 was added. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0042] [Example 14] To 150.00 g of a dispersion of phosphorus-doped tin oxide particles (PTO particles) (particle solid content concentration 5.33 wt %, dispersion medium "ethanol", primary particle diameter 20 nm, volume average particle diameter 68 nm), 10.00 g of the same aqueous dispersion of CNT as in Example 1 was added. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0043] [Comparative Example 1] 0.10 g of a surfactant (Fujifilm Wako Pure Chemical Industries, Ltd., polyacrylic acid molecular weight 25,000) was added to 9.90 g of water and stirred for 10 minutes to prepare an aqueous dispersion. 10.00 g of the aforementioned aqueous dispersion was added to 150.00 g of a dispersion of antimony-doped tin oxide particles (ATO particles) (particle solids concentration 5.33 wt %, dispersion medium "ethanol", primary particle diameter 20 nm, volume average particle diameter 32 nm). Ultrasonic waves were applied to this mixed solution as in Example 1. This produced a dispersion of ATO particles (particle dispersion).

[0044] Comparative Example 2 To 150.00 g of a dispersion of antimony particles (particle solid content concentration 5.33 wt %, dispersion medium "methanol", primary particle diameter 20 nm, volume average particle diameter 30 nm), 10.00 g of the same aqueous dispersion as in Comparative Example 1 was added. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a dispersion of antimony particles (particle dispersion) was obtained.

[0045] Comparative Example 3 To 150.00 g of a dispersion of antimony-doped tin oxide particles (particle solid content concentration 16.00 wt %, dispersion medium "ethanol", primary particle diameter 20 nm, volume average particle diameter 32 nm) was added 10.00 g of the same aqueous dispersion of CNTs as in Example 1. When ultrasonic waves were applied to this mixed solution in the same manner as in Example 1, the dispersion thickened and a uniform solution could not be obtained.

[0046] Comparative Example 4 First, a dispersion of chain particles in which primary particles of antimony-doped tin oxide particles are linked in a chain shape (particle solids concentration 5.33 wt %, dispersion medium "ethanol and water mixture, water content 4.07 wt %", primary particle diameter 8 nm, volume average particle diameter 60 nm) is prepared. 10.00 g of the same aqueous dispersion of CNTs as in Example 1 is added to 150.00 g of this particle dispersion. When ultrasound is applied to this mixed solution as in Example 1, the dispersion thickens and aggregates are generated.

[0047] Comparative Example 5 A dispersion of antimony-doped tin oxide particles (particle solid concentration 5.05 wt %, dispersion medium "ethanol", primary particle diameter 20 nm, volume average particle diameter 32 nm) was prepared. 1.00 g of the same aqueous dispersion of CNT as in Example 1 was added to 95.00 g of this particle dispersion. Ultrasonic waves were applied to this mixed solution in the same manner as in Example 1. As a result, a mixed dispersion was obtained.

[0048] Comparative Example 6 To 150.00 g of a dispersion of antimony-doped tin oxide particles (particle solid content concentration 5.33 wt %, dispersion medium "4-methyl-2-pentanone", primary particle diameter 20 nm, volume average particle diameter 25 nm) was added 10.00 g of the same aqueous dispersion of CNT as in Example 1. When ultrasound was applied to this mixed solution in the same manner as in Example 1, black aggregates were generated.

[0049] [Table 1]

[0050] [Table 2]

Claims

1. A dispersion liquid containing conductive particles, a fibrous conductor, and a hydrophilic organic solvent, the weight ratio of the conductive particles to the fibrous conductor (conductive particles / fibrous conductor) is in the range of 100 to 1000; the conductive particles contained in the dispersion liquid are less than 15% by weight, the conductive particles include first conductive particles bonded to the fibrous conductor and second conductive particles not bonded to the fibrous conductor, and the weight ratio of the second conductive particles to the first conductive particles (second conductive particles / first conductive particles) is in the range of 0.5 to 20; A dispersion characterized in that the water content of the dispersion is less than 9.5% by weight.

2. The dispersion according to claim 1, wherein the weight ratio of the first conductive particles to the fibrous conductor (first conductive particles / fibrous conductor) is in the range of 15 to 500.

3. 2. The dispersion according to claim 1, wherein the concentration of the fibrous conductor is 0.001 to 0.1% by weight.

4. 2. The dispersion according to claim 1, wherein the length of the fibrous conductor is 100 to 5,000 nm and the ratio of length to width (length / width) is in the range of 50 to 5,000.

5. 2. The dispersion according to claim 1, wherein the conductive particles have an average particle size of 1 to 50 nm.

6. A coating liquid for forming a conductive film, comprising the dispersion liquid according to claim 1 and a binder component.

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