Conductive material dispersion liquid, conductive film, and method for producing conductive material dispersion liquid

Abstract

An object of the present invention is to provide a conductive material dispersion capable of forming a conductive film having both transparency and conductivity. 【Solution means】A conductive material dispersion containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C), wherein the carbon-based conductive material (A) includes a multi-walled carbon nanotube (A-1), and a conductive material dispersion in which the iron content in the multi-walled carbon nanotube (A-1) exceeds 0% by mass and is 5% by mass or less, and the total content of cobalt and molybdenum is 0% by mass or more and 0.1% by mass or less.

Description

Technical Field

[0001] The present invention relates to a conductive material dispersion liquid.

Background Art

[0002] The transparent conductive films used in displays, electrodes of solar cells, electromagnetic wave shielding materials, etc. need to have both transparency and conductivity, and ITO films have been used. However, a conductive material dispersion liquid in which a conductive material is dispersed in a liquid has been developed for cost reduction.

[0003] For example, Patent Document 1 discloses a carbon material dispersion liquid containing at least two carbon materials selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon black, an aqueous medium, a dispersant, and a binder resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, single-walled carbon nanotubes have higher conductivity than multi-walled carbon nanotubes, but their high price has made it difficult to reduce the cost of conductive films. In addition, single-walled carbon nanotubes are as thin as 1 to 2 nm in diameter and very likely to aggregate. Therefore, there has been a problem that aggregated foreign matters and coating unevenness remain in the conductive film coated with the dispersion liquid, resulting in a decrease in transparency. On the other hand, multi-walled carbon nanotubes have a problem that the transparency of the conductive film decreases because a large amount of them needs to be used to obtain the desired conductivity. In addition, although carbon black has high dispersibility and stability, it has a problem of insufficient conductivity. Therefore, the conventional dispersion liquids have not been able to achieve both conductivity and transparency.

[0006] An object of the present invention is to provide a conductive material dispersion capable of forming a conductive film having both transparency and conductivity.

Means for Solving the Problems

[0007] <1>A conductive material dispersion containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C), wherein the carbon-based conductive material (A) includes multi-walled carbon nanotubes (A-1), and the content of iron in the multi-walled carbon nanotubes (A-1) is more than 0% by mass and 5% by mass or less, and the total content of cobalt and molybdenum is 0% by mass or more and 0.1% by mass or less, a conductive material dispersion. <2>The specific surface area of the multi-walled carbon nanotubes (A-1) is 400 m 2 / g or less, the conductive material dispersion of <1>. <3>The average aspect ratio of the multi-walled carbon nanotubes (A-1) is 300 or more and 2000 or less, the conductive material dispersion of <1> or <2>. <4>The average outer diameter of the multi-walled carbon nanotubes (A-1) is 5 nm or more and 30 nm or less, the conductive material dispersion of any one of <1> to <3>. <5>In 100% by mass of the non-volatile content of the conductive material dispersion, it is 0.01% by mass or more and 5% by mass or less, the conductive material dispersion of any one of <1> to <4>. <6>The dispersant (B) includes at least one dispersant selected from the group consisting of a nonionic dispersant, an anionic dispersant, a cationic dispersant, and an amphoteric dispersant, the conductive material dispersion of any one of <1> to <5>. <7>The thixotropic index of the conductive dispersion is 2 or more and 10 or less, the conductive material dispersion of any one of <1> to <6>. <8>The D50 particle size of the conductive dispersion is 10 μm or more and 150 μm or less, the conductive material dispersion of any one of <1> to <7>. <9>Further containing a resin (E), the conductive material dispersion of any one of <1> to <8>. <10>Further containing non-conductive particles (F), the conductive material dispersion of any one of <1> to <9>. Among the non-volatile components of the conductive material dispersion liquid, the content of the carbon-based conductive material (A) is 0.01% by mass or more and 3% by mass or less, and the conductive material dispersion liquid is any one of <1> to <10>. <12>A conductive film containing a carbon-based conductive material (A), a dispersant (B), and a resin (E), The carbon-based conductive material (A) includes multi-walled carbon nanotubes (A-1), A conductive film in which the iron content in the multi-walled carbon nanotubes (A-1) exceeds 0% by mass and is 5% by mass or less, and the total content of cobalt and molybdenum is 0% by mass or more and 0.1% by mass or less. <13>The conductive film of <12>, wherein the resin (E) is a binder resin. <14>A method for producing a conductive material dispersion liquid obtained by subjecting a mixture containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C) to dispersion treatment using a media-less disperser selected from the group consisting of a rotor-stator type disperser, an ultrasonic disperser, and a high-pressure homogenizer, The carbon-based conductive material (A) includes multi-walled carbon nanotubes (A-1), A method for producing a conductive material dispersion liquid, wherein the iron content in the multi-walled carbon nanotubes (A-1) exceeds 0% by mass and is 5% by mass or less, and the total content of cobalt and molybdenum is 0% by mass or more and 0.1% by mass or less. <15>A method for producing a conductive material dispersion liquid containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C), wherein the carbon-based conductive material (A) includes multi-walled carbon nanotubes (A-1), The iron content in the multi-walled carbon nanotubes (A-1) exceeds 0% by mass and is 5% by mass or less, and the total content of cobalt and molybdenum is 0% by mass or more and 0.1% by mass or less, A method for producing a conductive material dispersion liquid having the following step (a). Step (a): A step of mixing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C) to prepare a mixed liquid, and then performing dispersion treatment at pH 7 or higher

Advantages of the Invention

[0008] According to the present invention, a conductive material dispersion capable of forming a conductive film having both transparency and conductivity can be provided. Further, according to the present invention, a method for manufacturing a conductive film and a conductive material dispersion can be provided.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described in detail. In the present specification, "other carbon-based conductive materials (A') other than the multi-walled carbon nanotubes (A-1)" may be referred to as "carbon-based conductive materials (A')". Further, in the present specification, when expressed as "(meth)acryl", "(meth)acryloyl", "(meth)acrylic acid", "(meth)acrylate", "(meth)acryloyloxy", unless otherwise specified, they respectively represent "acryl or methacryl", "acryloyl or methacryloyl", "acrylic acid or methacrylic acid", "acrylate or methacrylate", "acryloyloxy or methacryloyloxy". The particles include not only spherical particles but also particles having an aspect ratio. In addition, various components appearing in the present specification may be used independently alone or in combination of two or more, unless otherwise noted. The TI value indicates the thixotropy index. CNT is an abbreviation for carbon nanotube. The numerical values specified in the present specification are values obtained by the methods disclosed in the embodiments or examples.

[0010] <Carbon-based conductive material (A)> The carbon-based conductive material (A) is particles mainly composed of carbon having conductivity. The carbon-based conductive material (A) includes multi-walled carbon nanotubes (A-1) and can further contain other carbon-based conductive materials (A') other than the multi-walled carbon nanotubes (A-1).

[0011] <Carbon nanotube> Carbon nanotubes are particles having a shape in which a planar graphene sheet is wound into a cylindrical shape and a fibrous structure. Carbon nanotubes include single-walled carbon nanotubes having a structure in which a single layer of graphene sheet is wound and multi-walled carbon nanotubes having a structure in which two or more layers of graphene sheets are wound. Further, the carbon nanotubes may partially have an amorphous structure. Note that the carbon nanotubes in the present invention are classified into multi-walled carbon nanotubes (A-1), multi-walled carbon nanotubes (A-2) other than multi-walled carbon nanotubes (A-1), and single-walled carbon nanotubes (A-3), which will be described later.

[0012] The shape of the carbon nanotubes is not particularly limited, and examples thereof include needle-like, cylindrical, fishbone-like (fishbone or cup stacking type), platelet-like (platelet), and coil-like. Among these, needle-like or cylindrical is preferable.

[0013] [Multi-walled carbon nanotubes (A-1)] Multi-walled carbon nanotubes (A-1) have an iron content exceeding 0% by mass and not exceeding 5% by mass, and a total content of cobalt and molybdenum of 0% by mass or more and 0.1% by mass or less. Iron is a component derived from the catalyst used in the synthesis of multi-walled carbon nanotubes (A-1). Since carbon nanotubes containing iron contain a branched structure that contributes to conductivity, high conductivity, transparency, and dispersibility can be achieved simultaneously. The iron content contained in multi-walled carbon nanotubes (A-1) is 5% by mass or less, preferably 4% by mass or less, more preferably 3% by mass or less, and even more preferably 1.5% by mass or less. The lower limit is not particularly limited, but is, for example, 0.1% by mass or more, and more preferably 0.5% by mass or more. The total content of cobalt and molybdenum in the multi-walled carbon nanotube (A-1) is 0 mass% or more and 0.1 mass% or less, preferably 0.05 mass% or less, more preferably 0.01 mass% or less, and even more preferably substantially not contained. Note that "substantially" means not intentionally contained.

[0014] In 100 mass% of the total content of the metal components contained in the multi-walled carbon nanotube (A-1), the total content of cobalt and molybdenum is preferably 10 mass% or less, more preferably 5 mass% or less, and even more preferably 2 mass% or less.

[0015] The multi-walled carbon nanotube (A-1) can be synthesized by chemical vapor deposition, arc discharge method or laser sublimation method. Among these, chemical vapor deposition is preferred.

[0016] The metal components other than cobalt and molybdenum contained in the multi-walled carbon nanotube (A-1) are preferably in particle form, and the average primary particle size thereof is more preferably 1 nm or more and 50 nm or less, even more preferably 3 nm or more and 40 nm or less, and even more preferably 5 nm or more and 30 nm or less. Note that the average primary particle size of the metal components contained in the multi-walled carbon nanotube (A-1) can be obtained by observing with a transmission electron microscope, selecting any about 20 particles and measuring the particle size, and calculating the number average value thereof.

[0017] The powder resistivity of the multi-walled carbon nanotube (A-1) is preferably 0.02 Ω·cm or less, more preferably 0.015 Ω·cm or less, and even more preferably 0.01 Ω·cm or less. Also, the lower limit of the powder resistivity is preferably as low as possible, and is 0.001 Ω·cm or more when strongly stated. Note that the powder resistivity of the multi-walled carbon nanotube (A-1) is a value obtained by measuring after compressing 1.0 g of the powder under a load of 25 Mpa using a resistivity meter (Loresta-GX MCP-T700 manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and a powder resistivity system (MCP-PD51 manufactured by Mitsubishi Chemical Analytech Co., Ltd.: four-probe ring electrode, electrode interval 5.0 mm, electrode radius 1.0 mm, sample radius 12.5 mm).

[0018] The average outer diameter of the multi-walled carbon nanotubes (A-1) is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more. Also, the average outer diameter is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 20 nm or less. Although the multi-walled carbon nanotubes (A-1) can form a bundle structure by aggregation of a plurality of particles, the average outer diameter is a value for individual primary particles. Incidentally, the average outer diameter of the multi-walled carbon nanotubes (A-1) can be obtained by observing the morphology of the carbon nanotubes at a magnification of 50,000 times with a transmission electron microscope, selecting any about 20 carbon nanotubes and measuring the length of the minor axis, and calculating the number average value thereof.

[0019] When a plurality of multi-walled carbon nanotubes (A-1) form a bundle-like structure (bundle structure), the average bundle diameter is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 15 nm or more. Also, it is preferably 70 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. Incidentally, the average bundle diameter of the multi-walled carbon nanotubes (A-1) can be obtained by observing the morphology of the carbon nanotubes at a magnification of 50,000 times with a transmission electron microscope, selecting any about 20 carbon nanotubes and measuring the length of the minor axis, and calculating the number average value thereof.

[0020] The average fiber length of the multi-walled carbon nanotubes (A-1) is preferably 0.1 μm or more and 50 μm or less, more preferably 0.5 μm or more and 40 μm or less, and even more preferably 1 μm or more and 20 μm or less. Incidentally, the average fiber length of the multi-walled carbon nanotubes (A-1) can be obtained by measuring the fiber length of any about 20 carbon nanotubes selected at a magnification of 10,000 times with a scanning electron microscope and calculating the number average value thereof.

[0021] The average aspect ratio of the multi-walled carbon nanotubes (A-1) is preferably 100 or more and 2000 or less, more preferably 150 or more and 1500 or less, and even more preferably 200 or more and 1000 or less. When the aspect ratio is 100 or more, the contact resistance between CNTs becomes small, and conductivity is likely to be exhibited. Further, when it is 2000 or less, a dispersion liquid with good fluidity can be obtained. The average aspect ratio of the multi-walled carbon nanotubes (A-1) can be calculated by dividing the average fiber length by the average outer diameter.

[0022] The specific surface area of the multi-walled carbon nanotubes (A-1) is preferably 100 m 2 / g or more, more preferably 150 m 2 / g or more, and even more preferably 200 m 2 / g or more. Further, it is preferably 800 m 2 / g or less, more preferably 400 m 2 / g or less, and even more preferably 300 m 2 / g or less. The specific surface area in the present invention is the BET specific surface area, and can be calculated by the BET multi-point method by the nitrogen adsorption method. After weighing 0.03 g of the multi-walled carbon nanotubes (A-1) using an electronic balance (manufactured by Sartorius, MSA225S100DI), drying is performed while degassing at 110°C for 15 minutes. Then, using a fully automatic specific surface area measuring device (manufactured by MOUNTECH, HM-model1208), the adsorption amount of nitrogen is measured using a helium-nitrogen mixed gas (helium:nitrogen = 7:3), whereby the specific surface area (m 2 / g) of the multi-walled carbon nanotubes (A-1) can be obtained.

[0023] By setting the average outer diameter, average fiber length, specific surface area, and average aspect ratio of the multi-walled carbon nanotubes (A-1) within the above ranges, dispersibility and conductivity can be achieved more highly in both respects.

[0024] The G / D ratio of the multi-walled carbon nanotubes (A-1) is preferably 0.1 or more and 3.0 or less, more preferably 0.3 or more and 2.0 or less, and even more preferably 0.5 or more and 1.0 or less. The G / D ratio is an indicator representing the crystallinity of carbon nanotubes and can be obtained by Raman spectroscopy. In the Raman spectrum of carbon nanotubes, the maximum peak intensity of the G band derived from graphite measured in the range of 1560 cm -1 or higher and 1600 cm -1 or lower is divided by the maximum peak intensity of the D band derived from amorphous carbon measured in the range of 1310 cm -1 or higher and 1350 cm -1 or lower to calculate it. The higher the G / D ratio, the higher the crystallinity, indicating excellent conductivity. The wavelength of the laser used in Raman spectroscopy is 532 nm.

[0025] From the perspective of conductivity, the purity of multi-walled carbon nanotubes (A-1) is preferably 95% by mass or more, more preferably 96% by mass or more, and even more preferably 97% by mass or more based on the mass of the carbon nanotubes. Also, the ash content contained in the carbon nanotubes is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less. The purity of the carbon nanotubes is represented by the value (% by mass) obtained by subtracting the ash content (% by mass) from the mass of the carbon nanotubes. The ash content (% by mass) of the carbon nanotubes can be measured, for example, in accordance with JIS K 6218-2.

[0026] The pH of multi-walled carbon nanotubes (A-1) is preferably pH 7.5 or higher, more preferably pH 8.0 or higher. The pH of the carbon nanotubes is the value measured with a pH meter after adding 1 g of carbon nanotubes to 50 g of ion-exchanged water at 25°C, treating it with an ultrasonic cleaner for 10 minutes to prepare a suspension.

[0027] Commercially available products of multi-walled carbon nanotubes (A-1) include, for example, ATHLOS manufactured by Cabot Corporation.

[0028] The content ratio of the multi-walled carbon nanotubes (A-1) in the carbon-based conductive material (A) is preferably 10 to 100% by mass, more preferably 20 to 100% by mass, still more preferably 50 to 100% by mass, and particularly preferably 80 to 100% by mass.

[0029] [Multi-walled carbon nanotubes (A-2)] The multi-walled carbon nanotubes (A-2) are multi-walled carbon nanotubes other than the multi-walled carbon nanotubes (A-1), and the total content ratio of cobalt and molybdenum is preferably more than 0.1% by mass and 5% by mass or less, more preferably 0.5% by mass or more and 4% by mass or less, and still more preferably 1% by mass or more and 3% by mass or less. As one embodiment, the conductive material dispersion of the present invention may further contain multi-walled carbon nanotubes (A-2).

[0030] The average outer diameter of the multi-walled carbon nanotubes (A-2) is preferably 3 nm or more, more preferably 5 nm or more. Also, it is preferably 30 nm or less, more preferably 20 nm or less. Although the multi-walled carbon nanotubes (A-2) can form a bundle structure by aggregation of a plurality of particles, the average outer diameter is the value in individual primary particles. Note that the average outer diameter of the multi-walled carbon nanotubes (A-2) can be obtained in the same manner as the multi-walled carbon nanotubes (A-1).

[0031] The average fiber length of the multi-walled carbon nanotubes (A-2) is preferably 0.1 μm or more and 200 μm or less, more preferably 1 μm or more and 100 μm or less, and still more preferably 3 μm or more and 50 μm or less. Note that the average fiber length of the multi-walled carbon nanotubes (A-2) can be obtained in the same manner as the multi-walled carbon nanotubes (A-1).

[0032] The average aspect ratio of the multi-walled carbon nanotubes (A-2) is preferably 100 or more and 10,000 or less, more preferably 250 or more and 5,000 or less, and still more preferably 500 or more and 2,000 or less. Note that the average aspect ratio of the multi-walled carbon nanotubes (A-2) can be obtained in the same manner as that of the multi-walled carbon nanotubes (A-1).

[0033] It is preferable that the average outer diameter, average fiber length, and average aspect ratio of the multi-walled carbon nanotubes (A-2) are within the above ranges because high dispersibility and conductivity can be achieved simultaneously.

[0034] Commercially available products of the multi-walled carbon nanotubes (A-2) include, for example, JENOTUBE10B (average outer diameter: 7 to 10 nm), JENOTUBE6A (average outer diameter: 5 to 7 nm) manufactured by JEIO Co., Ltd., FT7320 (average outer diameter: 7 to 11 nm) manufactured by Cnano Co., Ltd., K-Nanos100P (average outer diameter: 10 to 15 nm), K-Nanos100T (average outer diameter: 10 to 15 nm) manufactured by Kumho Petrochemical Co., Ltd., BT1001M (average outer diameter: 10 to 15 nm) manufactured by LG chem Ltd., and the like.

[0035] The content of the multi-walled carbon nanotubes (A-2) is preferably 0.1 to 100 parts by mass, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less with respect to 100 parts by mass of the multi-walled carbon nanotubes (A-1). By blending at this ratio, the dispersibility is improved while maintaining the conductivity.

[0036] [Single-walled carbon nanotubes (A-3)] As one embodiment, the conductive material dispersion of the present invention may further contain single-walled carbon nanotubes (A-3).

[0037] The powder resistivity of the single-walled carbon nanotubes (A-3) is preferably 0.02 Ω·cm or less, more preferably 0.01 Ω·cm or less, and even more preferably 0.005 Ω·cm or less. Also, since the lower the resistivity, the better, there is no particular lower limit, but for example, it is 0.0001 Ω·cm or more. Note that the powder resistivity of the single-walled carbon nanotubes (A-3) can be obtained in the same manner as that of the multi-walled carbon nanotubes (A-1).

[0038] The average outer diameter of the single-walled carbon nanotube (A-3) is preferably 1 nm or more, more preferably 1.5 nm or more, and even more preferably 2 nm or more. Also, it is preferably 10 nm or less, more preferably 5 nm or less, and even more preferably 3 nm or less. The single-walled carbon nanotube (A-3) may have a bundle structure formed by aggregation of a plurality of particles, but the average outer diameter is the value for individual primary particles. The average outer diameter of the single-walled carbon nanotube (A-3) can be obtained by observing the morphology of the carbon nanotube at a magnification of 100,000 times with a transmission electron microscope, selecting any about 20 carbon nanotubes, measuring the length of the short axis, and calculating the number average value thereof.

[0039] The average fiber length of the single-walled carbon nanotube (A-3) is preferably 0.1 μm or more and 200 μm or less, more preferably 1 μm or more and 100 μm or less, and even more preferably 3 μm or more and 50 μm or less. Note that the average fiber length of the single-walled carbon nanotube (A-3) can be obtained in the same manner as the multi-walled carbon nanotube (A-1).

[0040] The average aspect ratio of the single-walled carbon nanotube (A-3) is preferably 100 or more and 30,000 or less, more preferably 500 or more and 20,000 or less, and even more preferably 1,000 or more and 10,000 or less. When the aspect ratio is 100 or more, the contact resistance between CNTs becomes small, and conductivity is easily exhibited. Also, when it is 30,000 or less, a dispersion liquid with good fluidity can be obtained. Note that the average aspect ratio of the single-walled carbon nanotube (A-3) can be obtained in the same manner as the multi-walled carbon nanotube (A-1).

[0041] The specific surface area of the single-walled carbon nanotube (A-3) is preferably 100 m 2 / g or more, more preferably 300 m 2 / g or more, and even more preferably 400 m 2 / g or more. Also, it is preferably 1200 m 2 / g or less, more preferably 1000 m 2 / g or less, and even more preferably 800 m2 More preferably, it is below / g. The specific surface area of the single-walled carbon nanotube (A-3) can be obtained in the same manner as that of the multi-walled carbon nanotube (A-1).

[0042] It is preferable that the average outer diameter, average fiber length, specific surface area, and average aspect ratio of the single-walled carbon nanotube (A-3) are within the above ranges because high dispersibility and conductivity can be achieved simultaneously.

[0043] The G / D ratio of the single-walled carbon nanotube (A-3) is preferably 1 or more, more preferably 10 or more, and even more preferably 20 or more. Although there is no particular limitation on the upper limit value, it is preferably 1000 or less. The G / D ratio of the single-walled carbon nanotube (A-3) can be obtained in the same manner as that of the multi-walled carbon nanotube (A-1).

[0044] Commercially available products of the single-walled carbon nanotube (A-3) include, but are not limited to, ZEONANO SG101 (average outer diameter: 3 to 5 nm) manufactured by Nippon Zeon Co., Ltd., TUBALL 01RW02 (average outer diameter: about 2 nm) manufactured by OCSiAl, etc.

[0045] The content of the single-walled carbon nanotube (A-3) is preferably 1 to 100 parts by mass, more preferably 5 to 50 parts by mass, and even more preferably 7 to 40 parts by mass with respect to 100 parts by mass of the multi-walled carbon nanotube (A-1). By blending at this ratio, aggregation of the single-walled carbon nanotube (A-3) can be suppressed, and both conductivity and transparency can be achieved.

[0046] [Other carbon-based conductive material (A') other than carbon nanotubes] The carbon-based conductive material (A') is other carbon-based conductive materials other than carbon nanotubes. Examples of the carbon-based conductive material (A') include carbon materials such as carbon black, fullerene, graphene, multi-layer graphene, and graphite. Note that graphene and multi-layer graphene are flaky, plate-like, or scaly particles and do not include cylindrical particles. When using the carbon-based conductive material (A'), it is easily available from the market, and from the viewpoints of conductivity and transparency, it is preferable to use carbon black.

[0047] Examples of carbon black include carbon blacks such as acetylene black, thermal black, furnace black, channel black, lamp black, and hollow carbon black. Further, carbon blacks subjected to oxidation treatment, graphitization treatment, or the like can also be used.

[0048] The powder resistivity of the carbon-based conductive material (A') is preferably 10 Ω·cm or less. There is no particular lower limit, but for example, it is 0.001 Ω·cm or more. The powder resistivity of the carbon-based conductive material (A') can be obtained in the same manner as that of the multi-layer carbon nanotube (A-1).

[0049] <Dispersant (B)> The dispersant (B) is a compound capable of dispersing the carbon-based conductive material (A).

[0050] The dispersant is preferably at least one dispersant selected from the group consisting of nonionic dispersants, anionic dispersants, cationic dispersants, and amphoteric dispersants. Further, at least one dispersant selected from the group consisting of anionic dispersants, cationic dispersants, and amphoteric dispersants is more preferable, and an anionic dispersant is even more preferable.

[0051] The dispersant (B) preferably has an acid value and / or an amine value. It is more preferable that the total of the acid value and the amine value of the non-volatile content of the dispersant (B) is 10 mgKOH / g or more and 500 mgKOH / g or less, and even more preferable that it is 70 mgKOH / g or more and 200 mgKOH / g or less. The total of the acid value and the amine value being within the above range is preferable because a dispersion effect, an anti-aggregation effect, and further an adsorption stability effect with the carbon-based conductive material can be obtained.

[0052] The non-volatile acid value of the dispersant (B) is determined by obtaining the acid value (mgKOH / g) from the titration amount at the isoelectric point using a potentiometric automatic titrator, and can be measured by the method described in the section of [Examples].

[0053] The non-volatile amine value of the dispersant (B) is a value obtained by converting the measured total amine value (mgKOH / g) to non-volatile content in accordance with the method of ASTM D 2074.

[0054] The dispersant (B) preferably has an acidic group. Examples of the acidic group include a carboxyl group, a sulfo group, a phosphoric acid group, etc. Among these, a carboxyl group and a phosphoric acid group are preferable, and a carboxyl group is more preferable. In addition, examples of the basic group possessed by the dispersant (B) include a primary amino group, a secondary amino group, a tertiary amino group, a quaternary ammonium base, etc.

[0055] When the dispersant (B) has an acidic group or a basic group, it can be further neutralized with a pH adjuster (D) described later and used. The neutralization of the dispersant (B) may be carried out after dissolving the dispersant (B) in the dispersion medium (C), or may be carried out by adding the pH adjuster (D) while suspending or dispersing the dispersant (B) in the dispersion medium (C).

[0056] Examples of the dispersant (B) include a low molecular weight dispersant, a high molecular weight dispersant, etc. Among these, a high molecular weight dispersant is preferable, and a resin type dispersant is more preferable. Here, the low molecular weight dispersant is a dispersant having a weight average molecular weight of less than 1000, and the high molecular weight dispersant is a dispersant having a weight average molecular weight of 1000 or more.

[0057] Among the resin type dispersants, synthetic resins include, for example, (meth)acrylic dispersants, polyurethane dispersants, urethane acrylate dispersants, polyether dispersants, polyester dispersants, polyvinyl alcohol, polyvinyl acetal, polyvinyl pyrrolidone, etc. Among these, (meth)acrylic dispersants, urethane acrylate dispersants, and polyether dispersants are preferable, and (meth)acrylic dispersants are more preferable.

[0058] Among resin-type dispersants, natural resins include, for example, natural polymer compounds such as gum arabic and natural rosin, modified rosin compounds such as hydrogenated rosin and polymerized rosin, and cellulose-based compounds such as hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose. Among these, cellulose-based compounds are preferred. In the present invention, resins obtained by modifying natural resins are regarded as natural resins.

[0059] The resin-type dispersant preferably has, as a functional group, at least one functional group selected from the group consisting of an aromatic group, a heterocyclic group, and a nitrile group. Examples of the aromatic group include a phenyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group. Examples of the heterocyclic group include a pyridyl group, a pyrazinyl group, a pyrimidinyl group, and a pyridazinyl group. Among these, a phenyl group, a naphthyl group, a pyridyl group, or a nitrile group is more preferred, and a nitrile group is even more preferred. By having these groups, the adsorption to the carbon-based conductive material becomes stronger, and the dispersion stability can be further improved.

[0060] Commercially available polymer dispersants include Disperbyk-180, 183, 184, 187, 190, 191, 192, 193, 194, 2010, 2013, 2015, 2090, 2091, 2095, 2096, etc. manufactured by BYK Chemie; SOLSPERSE-20000, 27000, 41000, 41090, 43000, 44000, 46000, 47000, 53095, 54000, etc. manufactured by Lubrizol Japan; Dispex AA4030, AA4040, AA4140, CX4230, CX4231, CX4234, CX4240, CX4320, Dispex Ultra FA4404, FA4416, FA4425, FA4431, FA4437, FA4480, FA4480, FA4483, PA4550, PA4560, PA4575, PA4585, etc. manufactured by BASF Japan; Joncryl HPD-196, HPD-96J, PDX-6137A, 63J, 60J, 70J, JDX-6639, JDX-6500, PDX-6102B, etc.; and Ajisper PA111, PB711, PB821, PB822, PB824, etc. manufactured by Ajinomoto Fine-Techno Co., Inc.

[0061] As the low molecular weight dispersant, a nonionic dispersant, an anionic dispersant, a cationic dispersant, or an amphoteric dispersant can be used.

[0062] Commercially available low molecular weight anionic dispersants include, for example, fatty acid salts, alkyl sulfate esters, alkyl aryl sulfonates, alkyl naphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, alkyl phosphates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl aryl ether sulfates, naphthalene sulfonic acid formalin condensates, and polyoxyethylene alkyl phosphate esters, etc.

[0063] Commercially available low-molecular-weight nonionic dispersants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, glycerol borate fatty acid ester, and polyoxyethylene glycerol fatty acid ester, etc.

[0064] Commercially available low-molecular-weight cationic dispersants include alkylammonium salts, alkylamine salts, alkylpyridinium salts, etc.

[0065] Commercially available low-molecular-weight amphoteric dispersants include alkyl betaine, alkyl imidazolinium betaine, alkyl carboxy betaine, alkyl hydroxy sulfobetaine, etc.

[0066] The weight average molecular weight of the dispersant (B) is preferably less than 100,000, more preferably 1,000 to 50,000, even more preferably 2,000 to 30,000, and even more preferably 5,000 to 20,000. By having an appropriate weight average molecular weight, the adsorptivity to the carbon-based conductive material is improved, and the dispersion stability of the conductive material dispersion liquid is further improved. The weight average molecular weight is the weight average molecular weight in terms of standard polystyrene determined by gel permeation chromatography (GPC) measurement, and can be measured by the method described in the section of [Examples].

[0067] The compounding amount of the dispersant (B) with respect to 100 parts by mass of the carbon-based conductive material (A) is preferably 1 to 1500 parts by mass, more preferably 100 to 1000 parts by mass, even more preferably 100 to 500 parts by mass, and even more preferably 100 to 300 parts by mass.

[0068] [(Meth)acrylic dispersant] The dispersant (B) can contain a (meth)acrylic dispersant (resin-type anionic dispersant) containing a structural unit derived from a carboxyl group-containing monomer. The carboxyl group is more preferably neutralized with a pH adjuster (D) before use. Furthermore, the dispersant (B) particularly preferably further contains a structural unit derived from a nitrile group-containing monomer.

[0069] Examples of the carboxyl group-containing monomer include carboxyl group-containing (meth)acrylates such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxypropyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxypropyl hexahydrophthalate, ethylene oxide-modified succinic acid (meth)acrylate, and β-carboxyethyl (meth)acrylate. Among these, it is preferable to use (meth)acrylic acid.

[0070] Examples of the nitrile group-containing monomer include (meth)acrylonitrile, and it is preferable to use acrylonitrile.

[0071] In 100% by mass of the (meth)acrylic dispersant, the content of the structural unit derived from the carboxyl group-containing monomer is preferably 1 to 50% by mass, more preferably 5% by mass or more, still more preferably 10% by mass or more, and particularly preferably 20% by mass or more. Also, the content is more preferably 40% by mass or less, and still more preferably 30% by mass or less. By setting the amount of the structural unit derived from the carboxyl group-containing monomer in this way, the affinity for the solvent can be improved while maintaining the dispersibility of the carbon-based conductive material (A).

[0072] In 100% by mass of the (meth)acrylic dispersant, the content of the structural unit derived from the nitrile group-containing monomer is preferably 10 to 99% by mass, more preferably 30% by mass or more, still more preferably 60% by mass or more, and particularly preferably 70% by mass or more. Also, the content is more preferably 95% by mass or less, still more preferably 90% by mass or less, and particularly preferably 80% by mass or less. When an appropriate amount of the structural unit derived from the nitrile group-containing monomer is contained, the dispersibility of the carbon-based conductive material (A) can be further improved while maintaining the affinity for the solvent.

[0073] In addition, the (meth)acrylic dispersant can be used by partially modifying carboxyl groups or nitrile groups. In addition, the (meth)acrylic dispersant can contain structural units derived from other monomers having a (meth)acryloyl group and structural units derived from monomers having a polymerizable unsaturated group other than the (meth)acryloyl group. Examples of the polymerizable unsaturated group other than the (meth)acryloyl group include a vinyl group and a (meth)allyl group.

[0074] Examples of other monomers having a (meth)acryloyl group include (meth)acrylic acid esters. Examples of the (meth)acrylic acid esters include chain aliphatic alkyl group-containing (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate; branched aliphatic alkyl group-containing (meth)acrylic acid esters such as 2-ethylhexyl (meth)acrylate and isostearyl (meth)acrylate; cyclic aliphatic alkyl group-containing (meth)acrylic acid esters such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; alicyclic epoxy group-substituted alkyl (meth)acrylic acid esters such as glycidyl (meth)acrylate and (3-ethyloxetan-3-yl)methyl (meth)acrylate; alkylene glycol monoalkyl ether group-substituted alkyl (meth)acrylic acid esters such as 2-methoxyethyl (meth)acrylate and polyethylene glycol monomethyl ether (meth)acrylate; and the like.

[0075] Examples of monomers having an aromatic group include styrenes such as styrene and α-methylstyrene; alkyl (meth)acrylic acid esters substituted with an aromatic group such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; monomers having an anthracenyl group such as vinyl anthracene and 9-anthryl (meth)acrylate; monomers having a naphthyl group such as vinyl naphthalene and 1-naphthyl (meth)acrylate; Monomers having a phenanthrenyl group such as vinylphenanthrene, (meth)acrylic acid (9-phenanthryl)methyl; and the like.

[0076] Examples of the monomers having a heterocyclic group include monomers having a pyridyl group such as vinylpyridine, pyridine (meth)acrylate; monomers having a pyridazinyl group such as vinylpyridazine, pyridazine (meth)acrylate; monomers having a pyrimidinyl group such as vinylpyrimidine, pyrimidine (meth)acrylate; monomers having a pyrazinyl group such as vinylpyrazine, pyrazine (meth)acrylate, and the like.

[0077] Examples of the method for synthesizing a (meth)acrylic dispersant include solution polymerization method, suspension polymerization method, bulk polymerization method, emulsion polymerization method, precipitation polymerization, etc. Among them, the solution polymerization method or precipitation polymerization method is preferred. The polymerization reaction system includes, for example, addition polymerization such as ionic polymerization, free radical polymerization, living radical polymerization, etc. Among them, free radical polymerization is preferred. Examples of the radical polymerization initiator include peroxides, azo initiators, etc. In addition, when polymerizing the dispersant, a molecular weight regulator such as a chain transfer agent can be used.

[0078] Examples of the chain transfer agent include alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, dodecyl mercaptan, 3-mercapto-1,2-propanediol; thioacetic acid esters such as octyl thioglycolate, nonyl thioglycolate, 2-ethylhexyl thioglycolate; 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, α-pinene, β-pinene, etc. In particular, 3-mercapto-1,2-propanediol, thioacetic acid esters, 2,4-diphenyl-4-methyl-1-pentene, 1-methyl-4-isopropylidene-1-cyclohexene, α-pinene, β-pinene, etc. are preferred in terms of the resulting polymer having a low odor.

[0079] The amount of the chain transfer agent used is preferably 0.01 to 4 parts by mass, more preferably 0.1 to 2 parts by mass, based on 100 parts by mass of the total monomers. By setting the chain transfer agent within the above range, the weight average molecular weight of the (meth)acrylic dispersant can be adjusted to a suitable range.

[0080] <Dispersion medium (C)> Examples of the dispersion medium (C) include water and organic solvents. In 100% by mass of the dispersion medium (C), the water content is preferably 20% by mass or more, more preferably 50% by mass or more, further preferably 80% by mass or more, and particularly preferably 100% by mass.

[0081] The organic solvent is preferably a water-soluble solvent.

[0082] Water-soluble solvents include alcohol-based ones (such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, benzyl alcohol, etc.), polyhydric alcohol-based ones (such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ether-based ones (such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.), amine-based ones (such as ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amide-based ones (such as N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methylcaprolactam, etc.), heterocyclic-based ones (such as cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, etc.), sulfoxide-based (dimethyl sulfoxide, etc.), sulfone-based (hexamethylphosphoramide, sulfolane, etc.), lower ketone-based (acetone, methyl ethyl ketone, etc.), and others, such as tetrahydrofuran, acetonitrile, etc.

[0083] <pH adjuster (D)> The pH adjuster (D) is a compound that neutralizes the functional groups of the dispersant (B). Depending on the functional groups of the dispersant (B), a basic compound or an acidic compound is used as the pH adjuster (D).

[0084] The basic compound is preferably an inorganic base, more preferably a hydroxide of an alkali metal, and even more preferably sodium hydroxide or potassium hydroxide. By using these basic compounds, the acidic groups of the dispersant (B) can be effectively neutralized, and a good dispersant function can be exhibited.

[0085] Note that the calculation of the blending amount of the dispersant (B) is calculated by regarding the total amount of the mass of the dispersant (B) before neutralization and the mass of the pH adjuster (D) as the mass of the dispersant (B).

[0086] The amount of the basic compound used is preferably 1 equivalent or more, more preferably 1.5 equivalents or more, and even more preferably 2 equivalents or more with respect to the acidic groups of the dispersant (B). Also, it is preferably 10 equivalents or less, more preferably 7 equivalents or less, and even more preferably 5 equivalents or less.

[0087] The acidic compound is preferably acetic acid or an inorganic acid. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid, etc.

[0088] The amount of the acidic compound used is preferably 1 equivalent or more, more preferably 1.5 equivalents or more, and even more preferably 2 equivalents or more with respect to the acidic groups of the dispersant (B). Also, it is preferably 8 equivalents or less, more preferably 6 equivalents or less, and even more preferably 4 equivalents or less.

[0089] <Resin (E)> Resin (E) is a binder resin, and examples thereof include natural resins and synthetic resins. The weight average molecular weight of resin (E) is preferably 100,000 or more, more preferably 200,000 or more, and particularly preferably 300,000 or more. Also, it is preferably 10,000,000 or less, more preferably 5,000,000 or less, and particularly preferably 1,000,000 or less.

[0090] Resin (E) includes, for example, acrylic resins, polyester resins, polyurethane resins, epoxy resins, phenoxy resins, polyamide resins, polyether resins, silicone resins, polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl ester resins, polyvinyl pyrrolidone resins, vinyl chloride resins, carbonate resins, unsaturated carboxylic acid resins, fluorine resins, celluloses, rosins, and natural rubbers, etc., as well as copolymers thereof. Among these, acrylic resins, polyester resins, polyurethane resins, or polyolefin resins are preferred, and acrylic resins are more preferred.

[0091] An emulsion of resin (E) can be used. The average primary particle diameter of the emulsion is preferably 10 nm or more, more preferably 50 nm or more, and even more preferably 100 nm or more. Also, it is preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 500 nm or less. Note that the average primary particle diameter of resin (E) is the number average value of the primary particle diameters measured by selecting any about 20 resin (E) in an enlarged image by a scanning electron microscope.

[0092] When resin (E) has reactive functional groups such as polymerizable unsaturated groups or epoxy groups, curability can be obtained. When resin (E) is a curable resin, a thermosetting resin or a photocurable resin is preferred, and a thermosetting resin is more preferred.

[0093] <Non-conductive particles (F)> Non-conductive particles (F) are insulating particles.

[0094] The non-conductive particles (F) include, for example, pigments, aluminum oxide, silica, amorphous silica, crystalline silica, magnesium hydroxide, calcium oxide, magnesium oxide, barium titanate, and the like.

[0095] Examples of the pigments include extender pigments, white pigments, black pigments, colored pigments, rust preventive pigments, etc., and they can be arbitrarily selected as necessary.

[0096] Examples of the extender pigments include calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, barium sulfate, aluminum hydroxide, talc, mica, kaolin, and the like.

[0097] Examples of the white pigments include titanium oxide, zinc oxide, and the like.

[0098] Examples of the black pigments include black iron oxide, and the like.

[0099] Examples of the colored pigments include diketopyrrolopyrrole-based pigments, anthraquinone-based pigments, quinacridone-based pigments, dioxazine-based pigments, perinone-based pigments, perylene-based pigments, thiazine indigo-based pigments, triazine-based pigments, benzimidazolone-based pigments, indole-based pigments such as benzisoindole, isoindoline-based pigments, isoindolinone-based pigments, quinophthalone-based pigments, naphthol-based pigments, phthalocyanine-based pigments, fluorene-based pigments, metal complex-based pigments, azo-based pigments such as azo, disazo, polyazo, and the like.

[0100] The non-conductive particles (F) preferably have a powder resistivity of 100 Ω·cm or more. The powder resistivity of the non-conductive particles (F) can be obtained by the same method as that of the multi-walled carbon nanotubes (A-1).

[0101] The non-conductive particles (F) preferably have a primary particle diameter of 10 nm to 100 μm, more preferably 50 nm to 10 μm, still more preferably 100 nm to 5 μm, and particularly preferably 200 nm to 2 μm.

[0102] The shape of the non-conductive particles (F) is not particularly limited, and examples thereof include spherical, plate-like, needle-like, fibrous, circular, cubic, scaly, flaky, and the like. Among these, spherical is preferred from the viewpoints of being easily and uniformly mixed with the dispersion liquid and the resin and being less likely to cause aggregation.

[0103] <Neutralizing agent (G)> The conductive material dispersion of the present invention can optionally adjust the pH with a neutralizing agent (G) as necessary. Examples of the neutralizing agent (G) include basic compounds or acidic compounds, and they can be used alone or in combination of two or more. Note that the neutralizing agent (G) is a different compound having a polarity opposite to that of the pH adjuster (D). That is, when an acidic compound is used as the pH adjuster (D), the neutralizing agent (D) is a basic compound, and when a basic compound is used as the pH adjuster (D), the neutralizing agent (D) is an acidic compound.

[0104] The acidic compound is not particularly limited, and an inorganic acid or an organic acid can be used. From the viewpoints of industrial handleability such as corrosiveness and safety, it is preferable to use an organic acid.

[0105] Examples of the organic acid include organic compounds having a carboxyl group, organic compounds having a phosphate group, organic compounds having a sulfo group, and the like. Among these, it is preferable to use a compound having a carboxyl group.

[0106] Examples of the organic compound having a carboxyl group include acetic acid, formic acid, propionic acid, butyric acid, valeric acid, oxalic acid, etc., and it is preferable to use acetic acid.

[0107] Examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.

[0108] The basic compound is not particularly limited, and an inorganic base or an organic base can be used, and it is preferable to use an inorganic base.

[0109] Inorganic bases include ammonia, and chlorides, hydroxides, carbonates, nitrates, sulfates, phosphates, tungstates, vanadates, molybdates, niobates, and borates of alkali metals or alkaline earth metals, etc. Among these, from the viewpoints of ease of availability from the market and ease of handling, it is preferable to use chlorides, hydroxides, or carbonates of alkali metals or alkaline earth metals, and it is more preferable to use hydroxides of alkali metals.

[0110] Examples of hydroxides of alkali metals include lithium hydroxide, sodium hydroxide, potassium hydroxide, etc., and it is even more preferable to use sodium hydroxide or potassium hydroxide. Examples of carbonates of alkali metals include lithium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, etc.

[0111] Organic bases include, for example, primary, secondary, tertiary, or quaternary alkylamines having an optionally substituted alkyl group with 1 to 40 carbon atoms, and other organic bases, etc. The number of carbon atoms of the optionally substituted alkyl group is preferably 1 to 10, and more preferably 1 to 5. Note that the optionally substituted alkyl group means that the hydrogen atom of the alkyl group may be substituted, and examples of the substituent include a hydroxy group, etc.

[0112] Examples of primary alkylamines having an optionally substituted alkyl group with 1 to 40 carbon atoms include methylamine, ethylamine, propylamine, butylamine, isobutylamine, 2-ethylhexylamine, laurylamine, stearylamine, oleylamine, 2-aminoethanol, 3-aminopropanol, 3-ethoxypropylamine, monoethanolamine, etc. Examples of secondary alkylamines having an optionally substituted alkyl group with 1 to 40 carbon atoms include dimethylamine, diethylamine, dipropylamine, 2-methylaminoethanol, etc. In addition, tertiary alkylamines having an optionally substituted alkyl group with 1 to 40 carbon atoms include trimethylamine, triethylamine, tri-n-butylamine, dimethylbenzylamine, 2-(dimethylamino)ethanol, and the like. In addition, quaternary alkylamines having an optionally substituted alkyl group with 1 to 40 carbon atoms include tetramethylammonium hydroxide, tetraethylammonium hydroxide, trimethyl(2-hydroxyethyl)ammonium hydroxide, and the like.

[0113] In addition, as other organic bases, compounds containing basic nitrogen atoms such as 1,8-diazabicyclo[5.4.0]undecene-7 (DBU), 1,5-diazabicyclo[4.3.0]nonene-5 (DBN), 1,4-diazabicyclo[2.2.2]octane (DABCO), imidazole, and 1-methylimidazole may be used.

[0114] The neutralizing agent (G) consumed by neutralization may form a neutral salt and remain contained in the conductive material dispersion or the conductive film.

[0115] <Other Additives> The conductive material dispersion may contain, as other additives, for example, dye derivatives, defoamers, leveling agents, rheology control agents, anti-settling agents, curing catalysts, antioxidants, ultraviolet absorbers, surface modifiers, and the like. Other additives can be added at any timing and by any method.

[0116] [Dye Derivative] A dye derivative is a compound having an acidic group, a basic group, a neutral group, etc. in an organic dye residue. Dye derivatives include, for example, compounds having acidic substituents such as a sulfo group, a carboxyl group, a phosphate group, and amine salts thereof, compounds having basic substituents such as a sulfonamide group and a tertiary amino group at the terminal, and compounds having neutral substituents such as a phenyl group and a phthalimidoalkyl group. Organic pigments include, for example, diketopyrrolopyrrole-based pigments, anthraquinone-based pigments, quinacridone-based pigments, dioxazine-based pigments, perinone-based pigments, perylene-based pigments, thiazine indigo-based pigments, triazine-based pigments, benzimidazolone-based pigments, indole-based pigments such as benzisoindole, isoindoline-based pigments, isoindolinone-based pigments, quinophthalone-based pigments, naphthol-based pigments, phthalocyanine-based pigments, fluorene-based pigments, metal complex-based pigments, azo-based pigments such as azo, disazo, polyazo, etc.

[0117] [Antifoaming agent] As the antifoaming agent, any conventionally known antifoaming agent can be used. Not limited to commercially available antifoaming agents, any substance having an antifoaming effect such as wetting agents, hydrophilic organic solvents, water-soluble organic solvents, etc. can be arbitrarily used. The antifoaming agent can be used alone or in combination of two or more.

[0118] Examples of the antifoaming agent include alcohol-based; ethanol, propanol, isopropanol, butanol, octyl alcohol, hexadecyl alcohol, acetylene alcohol, ethylene glycol monobutyl ether, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, acetylene glycol, polyoxyalkylene glycol, propylene glycol, and other glycols, etc. Fatty acid ester-based; diethylene glycol laurate, glycerin monolinoleate, alkenyl succinic acid derivatives, sorbitol monolaurate, sorbitol trioleate, polyoxyethylene monolaurate, polyoxyethylene sorbitol monolaurate, natural wax, etc. Amide-based; polyoxyalkylene amide, acrylate polyamine, etc. Phosphate ester-based; tributyl phosphate, sodium octyl phosphate, etc. Metal soap-based; aluminum stearate, calcium oleate, etc. Oil and fat-based; animal and vegetable oils, sesame oil, castor oil, etc. Mineral oil-based: kerosene, paraffin, etc. Silicone-based; examples include dimethyl silicone oil, silicone paste, silicone emulsion, organically modified polysiloxane, fluorosilicone oil, etc.

[0119] <Conductive material dispersion> The conductive material dispersion of the present invention contains a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C). The carbon-based conductive material (A) includes multi-walled carbon nanotubes (A-1), and the iron content in the multi-walled carbon nanotubes (A-1) is more than 0% by mass and 5% by mass or less, and the total content of cobalt and molybdenum is 0% by mass or more and 0.1% by mass or less.

[0120] The conductive material dispersion of the present invention can form a conductive film that combines transparency and conductivity by including multi-walled carbon nanotubes (A-1) (hereinafter referred to as multi-walled CNT (A-1)). Since multi-walled CNT (A-1) has a branched structure, CNTs contact each other during the formation of the conductive film to form a three-dimensional conductive network. As a result, a desired conductivity can be obtained with a smaller amount than before, so a conductive film that combines transparency and conductivity can be formed. Multi-walled CNT (A-1) can be produced by using iron as a catalyst without substantially using cobalt and molybdenum during production. Since multi-walled CNT (A-1) has a very branched structure, a three-dimensional conductive network can be realized even when the branched chains break during the dispersion process when producing the conductive material dispersion. However, since there is no parameter indicating the degree of branching of multi-walled CNT (A-1), in this specification, the multi-branched structure is indicated by the content of the production catalyst of multi-walled CNT (A-1).

[0121] In 100% by mass of the non-volatile content in this dispersion, the content of the carbon-based conductive material (A) is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, and even more preferably 2% by mass or less. Also, it is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more.

[0122] The content of the multi-walled carbon nanotubes (A-1) is preferably 0.01 to 15% by mass, more preferably 0.1 to 5% by mass, and even more preferably 0.2 to 1% by mass in the conductive material dispersion liquid. By setting the content rate of the multi-walled carbon nanotubes (A-1) within this range, the generation of sediment and aggregates can be suppressed, and the dispersion state becomes uniform and good, which is preferable.

[0123] When using the multi-walled carbon nanotubes (A-2), the content of the multi-walled carbon nanotubes (A-2) is preferably 0.01 to 7.5% by mass, more preferably 2.5% by mass or less, and even more preferably 0.5% by mass or less in the conductive material dispersion liquid. By setting the content rate as above, it is preferable because the dispersion stability and conductivity can be achieved simultaneously without inhibiting the conductive network of the multi-walled carbon nanotubes (A-1).

[0124] When using the single-walled carbon nanotubes (A-3), the content rate of the single-walled carbon nanotubes (A-3) is preferably 0.01 to 7.5% by mass, more preferably 2.5% by mass or less, and even more preferably 0.5% by mass or less in the conductive material dispersion liquid. By setting the content rate as above, the dispersion stability and conductivity can be achieved at a high level without inhibiting the conductive network of the multi-walled carbon nanotubes (A-1).

[0125] In the conductive material dispersion liquid, when using the resin (E), the content of the dispersant (B) with respect to 100 parts by mass of the resin (E) is preferably 0.001 part by mass or more and 4 parts by mass or less, and more preferably 0.01 part by mass or more and 2 parts by mass or less.

[0126] The content of the non-conductive particles (F) is preferably 1% by mass or more and 70% by mass or less, more preferably 1% by mass or more and 65% by mass or less, and even more preferably 1% by mass or more and 60% by mass or less in 100% by mass of the conductive material dispersion liquid.

[0127] As one embodiment, in the conductive dispersion liquid containing resin (E) and non-conductive particles (F), in 100% by mass of the non-volatile content of the conductive dispersion liquid, the content of resin (E) is preferably 1% by mass or more and 99.9% by mass or less, more preferably 5% by mass or more and 90% by mass or less, and even more preferably 10% by mass or more and 80% by mass or less.

[0128] The content of the defoaming agent is preferably 0.01 to 1% by mass, more preferably 0.01 to 0.5% by mass, and even more preferably 0.05 to 0.2% by mass in the conductive material dispersion liquid. By setting the content rate of the defoaming agent within this range, good defoaming properties can be obtained.

[0129] The viscosity of the conductive material dispersion liquid preferably has a TI value obtained by the following formula (1) of 2 or more, more preferably 2.5 or more, and even more preferably 3 or more. Also, the TI value is preferably 10 or less, more preferably 7 or less, and even more preferably 5 or less. Formula (1) TI value = (viscosity measured at 6 rpm / viscosity measured at 60 rpm) Note that the viscosity of the conductive material dispersion liquid can be obtained by the method described in the examples. By setting the TI value within this range, a dispersion liquid in which the dispersion liquid is less likely to separate and settle and has good storage stability can be obtained.

[0130] The 50% particle diameter (D50) of the conductive material dispersion liquid is preferably 10 μm or more and 150 μm or less, more preferably 20 μm or more and 140 μm or less, and even more preferably 30 μm or more and 130 μm or less. By setting it within this range, it is possible to highly balance the viscosity and TI value of the dispersion liquid and the conductivity when forming the conductive film. Incidentally, the 50% particle size (D50) of the conductive material dispersion can be measured by the following method using a laser diffraction particle size distribution analyzer (manufactured by Microtrac Bell, Microtrac MT3000II). First, 0.5 g of the conductive material dispersion is diluted with 30 g of water, and then the measurement sample is prepared by treating it with an ultrasonic homogenizer (output 100 W) for 5 minutes. Next, 1 to 10 drops of the measurement sample are injected into the measurement cell, diluted with a sufficient amount of water, the particle size distribution is measured at 25°C, and the analysis is performed with a particle refractive index of 1.746 and a solvent refractive index of 1.33. Then, the particle size corresponding to the integrated value of 50% (volume basis) in the obtained particle size distribution was defined as the 50% particle size (D50).

[0131] The surface resistivity (R1) of the coating film of the conductive material dispersion is preferably 1.0×10 5 Ω / sq or less, more preferably 1.0×10 4 Ω / sq or less, and even more preferably 1.0×10 3 Ω / sq or less. Since the lower the surface resistivity (R1) of the coating film, the more preferable, there is no particular lower limit. For example, it is 1.0×10 -2 Ω / sq or more. Incidentally, the surface resistivity (R1) of the coating film was measured using Loresta-GX MCP-T700 (manufactured by Mitsubishi Chemical Analytech Co., Ltd., four-terminal method) for a coating film prepared by coating the conductive material dispersion on a polyethylene terephthalate (PET) film with a 7-mil applicator, leveling at 20°C for 10 minutes, and then drying at 100°C for 20 minutes.

[0132] The lightness (L1) of the coating film of the conductive material dispersion is preferably 25 or less, more preferably 23 or less, and even more preferably 20 or less. Also, the lightness is preferably 0 or more, more preferably 3 or more, and even more preferably 5 or more. Also, the chromaticity b value (b1) of the coating film of the conductive material dispersion is preferably 3 or less, more preferably 2 or less, and even more preferably 1 or less. Also, the chromaticity b value is preferably -10 or more, more preferably -5 or more, and even more preferably -3 or more. Although the reason is not clear, it has been found that when the lightness and b value of the coating film satisfy the above numerical ranges, the carbon-based conductive material (A) can be dispersed in a state where conductivity and transparency can be particularly highly compatible. Note that the lightness (L1) and b value (b1) of the coating film can be obtained by the method described in the examples.

[0133] In addition, this dispersion can further contain resin (E) and non-conductive particles (F). Moreover, it can be suitably used for applications where conductivity is required, and more preferably used as a conductive paint. Examples of the conductive paint include antistatic paint, transparent conductive paint, electrode paint, etc. Among these, the applications of antistatic paint or transparent conductive paint are preferred because of their excellent transparency.

[0134] <Manufacture of Conductive Material Dispersion> The conductive material dispersion of the present invention disperses a carbon-based conductive material (A) containing multi-walled carbon nanotubes (A-1) in a dispersion medium (C) using a dispersant (B). In this case, the dispersant (B) and the carbon-based conductive material (A) are added simultaneously or sequentially and mixed, so that the dispersant (B) acts (adsorbs) on the carbon-based conductive material (A) while dispersing. From the viewpoint of workability, it is preferable to dissolve, swell, or disperse the dispersant (B) in water, and then add and mix the carbon-based conductive material (A) to cause the dispersant (B) to act (adsorb) on the carbon-based conductive material (A).

[0135] The dispersion device is not particularly limited, and any conventionally known disperser can be used. For example, rotor-stator type dispersers such as colloid mills ("PUC colloid mill" manufactured by PUC Co., "Colloid mill MK" manufactured by IKA Co.), homogenizers ("Creamix" manufactured by M Technique Co., "Filmix" manufactured by PRIMIX Co., etc., "Abramix" manufactured by Silver Sonics Co., etc.), cone mills ("Cone mill MKO" manufactured by IKA Co., etc.), ultrasonic dispersers such as UP200St manufactured by Hielscher Co., etc., high-pressure homogenizers such as wet jet mills ("Genus PY" manufactured by Genus Co., "Starburst" manufactured by Sugino Machine Co., "Nanomizer" manufactured by Nanomizer Co., etc.), mixers such as disper, homomixer, planetary mixer, etc. Paint conditioner (manufactured by Red Building Co., Ltd.), ball mill, sand mill (such as "Dynomill" manufactured by Simar Enterprises Co., Ltd.), attritor, pearl mill (such as "DCP mill" manufactured by Erie Co., Ltd.), and media type dispersers such as coball mill. Among these, at least one media-less disperser selected from the group consisting of a rotor-stator type disperser, an ultrasonic disperser, and a high-pressure homogenizer is preferable, a rotor-stator type disperser or a high-pressure homogenizer is more preferable, and a high-pressure homogenizer is even more preferable. Furthermore, among high-pressure homogenizers, it is even more preferable to use a disperser equipped with a mechanism for performing dispersion treatment by the impact force of cavitation. Examples of such a disperser include the "Single Nozzle Chamber" model of "Starburst" manufactured by Sugino Machine Co., Ltd.

[0136] As one embodiment using a high-pressure homogenizer that performs dispersion treatment by the impact force of cavitation, it is preferable to perform dispersion treatment by passing the mixed liquid to be dispersed through at an injection pressure of 50 Mpa or more and 150 Mpa or less. By setting the dispersion treatment conditions in this way, it is possible to uniformly disperse the multi-walled carbon nanotube (A-1) structure without excessively damaging it, and particularly good conductivity can be obtained. Note that the pass dispersion of the present invention refers to a method of sequentially supplying the entire amount of the sample liquid to the dispersion site of the disperser for dispersion treatment, and one pass dispersion is called when the entire amount of the sample liquid has passed through the dispersion site of the disperser once. By taking this step, since the entire sample liquid surely passes through the dispersion site of the disperser, a homogeneous treatment can be performed.

[0137] As one embodiment for manufacturing a conductive material dispersion liquid, it is preferable to include the following steps. First, a mixed liquid containing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C) is prepared, and the pH is adjusted to 7.0 or more to make it basic. When a polymer dispersant containing a carboxyl group-containing monomer unit is used as the dispersant (B), the pH can also be adjusted to 7.5 or more by sufficiently neutralizing the carboxyl group with a pH adjuster (D). Next, the mixture is subjected to a dispersion treatment using a rotor-stator type disperser. For example, using magic LAB (manufactured by IKA), the clearance value between the rotor and the stator is set to 318 μm, and the entire amount of the mixture is passed once between the rotor (IKA IdentNo.U080674) and the stator (IKA IdentNo.U083555) for dispersion treatment (1-pass dispersion). Then, the dispersion treatment time per 1 kg of the mixture is set to 15 minutes for circulation dispersion to obtain a preliminary dispersion liquid. Thereafter, further dispersion treatment is performed using a high-pressure homogenizer. For example, using Starburst Rabor (manufactured by Sugino Machine) equipped with a single nozzle chamber, by performing 10 passes of path dispersion on the entire amount of the preliminary dispersion liquid at a nozzle diameter of 0.2 mm, an injection pressure of 100 Mpa, and a discharge rate of 700 g / min, a conductive material dispersion liquid can be obtained.

[0138] Also, for the production of the conductive material dispersion liquid, it is preferable to perform the following steps (a) and (b). [Step (a)] A step of mixing a carbon-based conductive material (A), a dispersant (B), and a dispersion medium (C) to prepare a mixture, and then performing a dispersion treatment at pH 7 or higher.

[0139] [Step (b)] A step of adjusting the pH to be 6 or higher and 13 or lower after step (a).

[0140] First, step (a) will be described in detail. The carbon-based conductive material (A) and the dispersant (B) may each have acidic or basic functional groups. In step (a), after mixing the carbon-based conductive material (A), the dispersant (B), and the dispersion medium (C), by adjusting the pH to 7 or higher and performing a dispersion treatment, good dispersibility can be obtained. The pH of this step is preferably 7.5 to 14, more preferably 8 to 14, and even more preferably 9 to 13.5. Although the mechanism of action is not clear, it is presumed that good dispersibility is exhibited by pre-adjusting the pH in the dispersion process to eliminate the influence on the pH derived from, for example, the carbon-based conductive material (A) and the dispersant (B), and further stably controlling the solubility and adsorptivity of the dispersant (B).

[0141] In step (a), as the dispersant (B), it is preferable to use an anionic or amphoteric polymer dispersant containing a carboxyl group-containing monomer unit. When using these polymer dispersants, the pH can also be adjusted to 7 or higher using a pH adjuster (D).

[0142] Next, step (b) will be described in detail. In step (a), the dispersion treatment is carried out in a neutral to basic environment. However, when the pH is high, problems such as corrosivity when storing the dispersion liquid in a container, safety during handling, and precipitation of the resin (E) when the resin (E) is added may occur. Therefore, in step (b), a neutralizing agent (G) is further added to adjust the pH so that the pH becomes 6 to 13. The adjusted pH is preferably 6 to 12, more preferably 7 to 12, and even more preferably 8 to 11. Also, the pH in step (b) is preferably 1 or more lower than the pH in step (a). In the present invention, after adjusting the pH within the above range, a conductive material dispersion liquid with good handleability can be obtained without impairing the dispersibility and storage stability of the dispersion liquid.

[0143] The pH in steps (a) and (b) is a value measured using a pH meter at a liquid temperature of 25°C. The pH meter can be measured using, for example, "pH Detector PH4C for Chemical Process" manufactured by Yokogawa Electric Corporation.

[0144] <Conductive film> The conductive film of the present invention contains a carbon-based conductive material (A), a dispersant (B), and a resin (E). The carbon-based conductive material (A) includes multi-walled carbon nanotubes (A-1). Further, non-conductive particles (F) can be blended as necessary. The conductive film of the present invention can be obtained, for example, by coating the conductive dispersion of the present invention on a substrate and drying and / or curing it.

[0145] In 100% by mass of the conductive film, the content of the carbon-based conductive material (A) is preferably 0.002% by mass or more and 4% by mass or less, more preferably 0.01% by mass or more and 2% by mass or less.

[0146] In 100% by mass of the conductive film, the content of the multi-walled carbon nanotube (A-1) is preferably 0.001% by mass or more and 2% by mass or less, more preferably 0.005% by mass or more and 1% by mass or less.

[0147] In the conductive film, the content of the dispersant (B) with respect to 100 parts by mass of the resin (E) is preferably 0.001 part by mass or more and 4 parts by mass or less, more preferably 0.01 part by mass or more and 2 parts by mass or less.

[0148] In 100% by mass of the conductive film, the total content of the dispersant (B) and the resin (E) is preferably 1% by mass or more, more preferably 5% by mass or more, further preferably 10% by mass or more, and further preferably 50% by mass or more. Also, the total content is preferably 99.9% by mass or less, more preferably 90% by mass or less.

[0149] The film thickness of the conductive film is preferably 0.01 μm or more and 100 μm or less, more preferably 0.1 μm or more and 50 μm or less.

[0150] The conductivity of the conductive film is preferably 1.0×10 -4 mS / cm or more, more preferably 1.0×10 -2 mS / cm or more, and further preferably 1 mS / cm or more.

[0151] When forming a conductive film by coating a conductive dispersion, for example, various known methods such as die coating method, dip coating method, roll coating method, doctor coating method, gravure coating method, screen printing method, brush painting, roller painting, spray painting, etc. can be used for coating. Also, after coating, it can be dried by a dryer. Examples of the dryer include normal temperature drying, air blower dryer, warm air dryer, infrared heater, far infrared heater, etc.

[0152] When using a curable resin as the resin (E), the curing method is not particularly limited, but examples include aging at normal temperature or under heating. The aging period for the curing reaction is, for example, about 1 to 5 days at 40 °C and about 2 to 10 hours at 180 °C. Also, if necessary, it is possible to proceed with the curing reaction in multiple temperature steps.

[0153] <Substrate> The conductive material dispersion of the present invention can be coated on various conventionally known substrates. Examples of the substrate include metal substrates such as iron, stainless steel, and aluminum; cement-based substrates such as cement and gypsum; plastic-based substrates such as polyvinyl chlorides, polyesters, polycarbonates, and acrylates, etc. Note that these substrates may be surface-treated.

[0154] Also, as the substrate, substrates of various shapes such as sheet-like, film-like, and plate-like can be used. These substrates may be used in a flat state or in a state having a curved surface. Also, if necessary, a roughening treatment or a smoothing treatment can be performed, and those with the roughness of the coating surface adjusted can be used.

Examples

[0155] Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the examples. In these examples, "parts" represents parts by mass. "%" represents mass %. Also, carbon nanotubes may be referred to as "CNT".

[0156] In this Example and Comparative Example, the following materials were used in the production of the conductive material dispersion. The carbon nanotubes used in the Example and Comparative Example contain those shown in Table 1 as metal components.

[0157] <Carbon-based conductive material> [Multi-walled carbon nanotube (A-1)] ·ATHLOS: ATHLOS SR1200 (multi-walled carbon nanotubes manufactured by Cabot Corporation, average outer diameter: 13 nm, specific surface area 210 m 2 / g, average aspect ratio 500) ·CNT-2: Prepared by the following method. 15 parts of ATHLOS SR1200 was weighed into a glass container, 800 parts of 15% hydrochloric acid was added, and then stirred well using a stirrer. Then, it was sufficiently diluted with purified water and filtered using a membrane filter. And after thoroughly washing away the hydrochloric acid with purified water, it was dried at 60 °C for 12 hours to obtain CNT-2. Average outer diameter: 13 nm, specific surface area 210 m 2 / g, average aspect ratio 500. ·CNT-3: Multi-walled carbon nanotubes, average outer diameter: 12 nm, specific surface area 250 m 2 / g, average aspect ratio 700.

[0158] [Multi-walled carbon nanotube (A-2)] ·6A: JENOTUBE6A (manufactured by JEIO, multi-walled carbon nanotubes, average outer diameter: 6 nm, specific surface area 700 m 2 / g, average aspect ratio 9700) ·100T: K-Nanos 100T (manufactured by Kumho Petrochemical, multi-walled carbon nanotubes, average outer diameter: 13 nm, specific surface area 240 m 2 / g, average aspect ratio 2600)

[0159] [Single-walled carbon nanotube (A-3)] ·TUBALL 01RW02: manufactured by OCSIAL, single-walled carbon nanotubes, average outer diameter: 1.5 nm, specific surface area 490 m 2 / g, average aspect ratio 3000.

[0160] [Carbon-based conductive material (A')] ·Li-400: DENKA BLACK Li-400 (manufactured by DENKA, primary particle diameter 48 nm, specific surface area 39 m 2 / g).

[0161] [Dispersant (B)] ·Copolymer B-1: (Meth)acrylic dispersant with nitrile group, resin-type dispersant. Weight average molecular weight 25000, acid value 175 mgKOH / g, non-volatile content 100%. ·Copolymer B-2: (Meth)acrylic dispersant with nitrile group, resin-type dispersant. Weight average molecular weight 45000, acid value 265 mgKOH / g, non-volatile content 100%. ·Copolymer B-3: (Meth)acrylic dispersant with nitrile group, resin-type dispersant. Weight average molecular weight 52000, acid value 125 mgKOH / g, non-volatile content 100%. ·Copolymer B-4: (Meth)acrylic dispersant with nitrile group, resin-type dispersant. Weight average molecular weight 52000, acid value 78 mgKOH / g, non-volatile content 100%. ·BYK-111: DISPERBYK-111 (manufactured by BYK-Chemie, copolymer with phosphate group). (Meth)acrylic dispersant with phosphate group, resin-type dispersant. Weight average molecular weight 2000, non-volatile acid value 129 mgKOH / g, non-volatile content 95% ·BYK-190: DISPERBYK-190 (manufactured by BYK-Chemie, styrene block copolymer). (Meth)acrylic dispersant with carboxyl group, resin-type dispersant. Weight average molecular weight 2400, non-volatile acid value 10 mgKOH / g, non-volatile content 40%. ·Joncryl 63J: Manufactured by BASF Japan, styrene-acrylic acid copolymer. (Meth)acrylic dispersant with neutralized carboxyl group, resin-type dispersant. Weight average molecular weight 12500, non-volatile acid value 213 mgKOH / g, non-volatile content 30% · D331: Spredox D-331 (manufactured by DOXA, a polyether compound having an acidic group and an amine-based functional group). Amphoteric resin-type dispersant. Weight-average molecular weight 23,000, acid value 12 mg KOH / g, amine value 28 mg KOH / g, active ingredient 100%. · EFKA4701: EFKA PX4701 (manufactured by BASF Japan, an acrylic block copolymer). (Meth)acrylic dispersant having a basic group, resin-type dispersant. Weight-average molecular weight 23,000, amine value 40 mg KOH / g, non-volatile content 100%. · CMC: Sunrose APP-84 (manufactured by Nippon Paper Industries Co., Ltd., sodium carboxymethyl cellulose). Anionic resin-type dispersant. Weight-average molecular weight 18,000, non-volatile content 100%. · K30: Polyvinylpyrrolidone K30 (manufactured by Nippon Shokubai Co., Ltd., polyvinylpyrrolidone, weight-average molecular weight 40,000). Nonionic resin-type dispersant.

[0162] <Dispersion medium (C)> · Water: Ion-exchanged water · IPA: Isopropyl alcohol · n-Butanol·PG: Propylene glycol · Butyl cellosolve: Ethylene glycol mononormal butyl ether

[0163] <pH adjuster (D)> · Sodium hydroxide · Potassium hydroxide

[0164] <Resin (E)> · NANOCRYL-S KPX-02-014: Acrylic resin emulsion, manufactured by Toyochem Co., Ltd. Non-volatile content 40% by mass. · Pes resin A-124GP: Polyester resin emulsion, manufactured by Takamatsu Oil & Fat Co., Ltd. Non-volatile content 30% by mass. · Takelac W-6110: Polyurethane resin emulsion, manufactured by Mitsui Chemicals, Inc. Non-volatile content 32% by mass. · Arrowbase SB-1230N: Polyolefin resin emulsion, manufactured by Unitika Ltd. Non-volatile content 25%. · Water-based Nigori Clear: Neo Water Base Nigori Clear, manufactured by Rock Paint Co., Ltd. Non-volatile content: 20%. · Cymel 325: Melamine resin, manufactured by Mitsui Cytec Co., Ltd. Non-volatile content: 100%.

[0165] <Non-conductive particles (F)> · NK-8G: Synthetic mica (synthetic fluorophlogopite), manufactured by Nippon Koken Kogyo Co., Ltd. Average primary particle size: 8 μm. · F-1: Ultra-fine zinc oxide, manufactured by Hakusui Tech Co., Ltd. Average primary particle size: 0.1 μm, specific gravity: 5.6 g / cm 3 , specific surface area: 10 m 2 / g. · TTO-51(A): Fine titanium oxide, manufactured by Ishihara Sangyo Co., Ltd. Average primary particle size: 0.02 μm, rutile type crystal, titanium purity: 80%, specific surface area: 80 m 2 / g. · ABL-412HP: High coloring power black iron oxide, manufactured by Titanium Industry Co., Ltd. Average primary particle size: 0.1 μm. · Lionol Blue FG-7351: Copper phthalocyanine pigment (C.I. Pigment Blue 15:3), manufactured by Toyo Color Co., Ltd. Specific surface area: 68 m 2 / g.

[0166] <Neutralizing agent (G)> · Acetic acid

[0167] <Other additives> · Defoaming agent: BYK-024 (manufactured by BYK-Chemie GmbH, silicone-based defoaming agent for water-based systems).

[0168] (Measurement of the amount of metal components contained in the carbon-based conductive material (A)) Using the measurement sample prepared by the microwave pressurized decomposition method as follows, it was measured by inductively coupled plasma optical emission spectrometry (ICP-OES). 50 mg of carbon-based conductive material (A) was precisely weighed into a pressure decomposition vessel made of Teflon (registered trademark), and 5 mL of nitric acid (concentration: 65% by mass) and 10 mL of perchloric acid (concentration: 70% by mass) were added. Subsequently, after heating at 120 °C for 15 minutes using a microwave pressure decomposition apparatus, and then further heating at 170 °C for 30 minutes, a decomposition solution (measurement sample) in which the carbon-based conductive material (A) was completely dissolved was obtained. In the case where a very small amount of insoluble residue remains during dissolution, it can be filtered using a membrane filter to remove the insoluble residue and used as the measurement sample. Next, the decomposition solution was analyzed using an ICP emission spectroscopic analyzer (manufactured by Agilent, Agilent 5800 ICP-OES, multi-type. Argon plasma light source), and the concentration of each metal contained in the decomposition solution was calculated by the absolute calibration curve method. For the analytical values of each metal element, emission lines without the influence of coexisting elements were used. For example, for iron, emission lines with wavelengths of 239 nm or 259 nm, for chromium, emission lines with wavelengths of 206 nm or 267 nm, and for molybdenum, emission lines with wavelengths of 203 nm or 281 nm can be used. In Table 1, the average values of the analytical values obtained at these wavelengths were used. Then, from the concentration of each metal contained in this decomposition solution, the amount of each metal contained in the carbon-based conductive material (A) was calculated and taken as the amount of metal components contained in the carbon-based conductive material (A). The amount of metal components contained in the carbon-based conductive material (A) obtained in this way is shown in Table 1. The metal content rates in Table 1 are in mass%, and "-" indicates that the content rate is 0.001 mass% or less.

[0169]

Table 1

[0170] The values in the table are in %. Note that copolymers B-1 to B-4 were synthesized according to the following production examples.

[0171] (Production Example 1: Synthesis of Copolymer B-1) A reaction vessel equipped with a gas inlet tube, a thermometer, a condenser, and a stirrer was charged with 100 parts of methyl ethyl ketone, 78.0 parts of acrylonitrile, 22.0 parts of acrylic acid, and 0.5 part of 3-mercapto-1,2-propanediol, and purged with nitrogen gas. The inside of the reaction vessel was heated to 70 °C, and a mixture consisting of 10 parts of methyl ethyl ketone and 0.4 part of 2,2'-azobis(2,4-dimethylvaleronitrile) (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.: V-65) was added dropwise into the reaction vessel over 6 hours to conduct a polymerization reaction. After completion of the dropwise addition, the reaction was carried out at 70 °C for 1 hour, then 0.1 part of V-65 was added, and the reaction was continued at 70 °C for 1 hour to obtain the product as a precipitate. Thereafter, it was confirmed by non-volatile content measurement that the conversion rate exceeded 98%. The product was separated by filtration under reduced pressure, washed with 100 parts of ethyl acetate, and the solvent was completely removed by drying under reduced pressure to obtain copolymer B-1. The weight average molecular weight of copolymer B-1 was 25,000. Also, the acid value was 175 mgKOH / g. Next, 2 parts of copolymer B-1, 0.5 part of sodium hydroxide as pH adjuster (D), and 96.9 parts of purified water were charged into a beaker, and a neutralization reaction was carried out by stirring at 25 °C and a disperser rotation speed of 500 rpm for 15 minutes to obtain a 10 mass% aqueous solution of copolymer B-1.

[0172] (Production Examples 2 to 4: Synthesis of Copolymers B-2 to B-4) Copolymers were synthesized in the same manner as in Production Example 1 except that the amounts of acrylonitrile and acrylic acid used were changed according to Table 2, and neutralized with pH adjuster (D) to prepare 10 mass% aqueous solutions. The weight average molecular weights and acid values (mg / KOH) of the respective copolymers were as shown in Table 2. The units of the blending amounts of acrylonitrile and acrylic acid shown in Table 2 are mass%. The blending amount of neutralizer (D) indicates the blending amount of neutralizer (D) per 1 part of the copolymer.

[0173]

Table 2

[0174] (Method for Measuring Acid Value of Dispersant (B)) The acid value of the dispersant (B) was calculated from the titration of the N-methyl-2-pyrrolidone solution of the dispersant (B). 1 g of the dispersant (B) was taken in a beaker (100 ml), 30 ml of N-methyl-2-pyrrolidone was added, and the mixture was stirred with a stirrer until dissolved. Then, it was further diluted with 20 ml of ion-exchanged water to obtain a solution to be titrated. This solution to be titrated was titrated with a 0.1 mol / L KOH / ethanol solution using an automatic potentiometric titrator (AT-710S, manufactured by Kyoto Electronics Industry Co., Ltd.), and the acid value (mgKOH / g) of the dispersant (B) was calculated from the titration amount at the isoelectric point.

[0175] (Method for measuring weight-average molecular weight) The weight-average molecular weight of the dispersant (B) was measured by gel permeation chromatography (GPC) equipped with a differential refractive index (RI) detector. The apparatus used was HLC-8320GPC (manufactured by Tosoh Corporation). Three separation columns were connected in series, and the packing materials used were "TSK-GEL SUPER AW-4000", "AW-300 0", and "AW-2500" manufactured by Tosoh Corporation in order. The oven temperature was 40 °C, and a solution of 30 mM triethylamine and 10 mM LiBr in N,N-dimethylformamide was used as the eluent. The measurement was carried out at a flow rate of 0.6 ml / min. A solution of the dispersant (B) was prepared to a concentration of 1 mass% in the above eluent, and 20 microliters was injected. The molecular weight is the converted value of standard polystyrene.

[0176] (Production of conductive material dispersion (1)) [Example 1-1] 0.5 part of ATHLOS as the multi-walled carbon nanotube (A-1), 25 parts of a 10 mass% neutralized aqueous solution of copolymer B-1 as the dispersant (B), 0.1 part of BYK-024 as the antifoaming agent, and 74.4 parts of water as the dispersion medium (C) were mixed to prepare a mixed solution. At this time, the pH of the mixed solution was 12.1. This mixed solution was dispersed with a colloid mill (magic LAB manufactured by IKA) for 30 minutes, and then subjected to 10 passes of dispersion at an injection pressure of 100 Mpa using a high-pressure homogenizer (Starburst Labo, single nozzle chamber manufactured by Sugino Machine Limited) to obtain a dispersion. Furthermore, 7 parts of 0.1 M acetic acid and 23 parts of water were added to this dispersion as a neutralizing agent (G) and mixed with a disper to obtain 130 parts of a conductive material dispersion (Fa-1). At this time, the pH of the conductive material dispersion (Fa-1) was 9.1.

[0177] [Examples 1-2 to 1-14, Comparative Examples 1-1 to 1-4] Conductive material dispersions Fa-2 to Fa-18 were obtained in the same manner as in Example 1-1, except that the types and amounts of the carbon-based conductive material (A) and the dispersant (B) were changed as shown in Table 3-1. The blending amount of the dispersant in Table 3-1 is the value in terms of non-volatile content, and the balance of the total amount is water as the dispersion medium (C). Also, acetic acid was used as the neutralizing agent (G) to adjust so that the pH before the dispersion treatment (corresponding to the timing of step (a)) and the pH after the dispersion treatment (corresponding to the timing of step (b)) would be the pH values in Table 3-2, respectively. In Table 3-2, those with "-" for the pH in step (b) indicate that the pH adjustment after the dispersion treatment was not carried out.

[0178] (Evaluation of Conductive Material Dispersion (1)) The evaluation of the conductive material dispersion produced in the production of the conductive material dispersion (1) was carried out by the following method.

[0179] (Viscosity) The viscosity was measured immediately after stirring the conductive material dispersion with a disper at a rotational speed of 1000 rpm for 5 minutes. The viscosity is the value obtained using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., "BL") for 1 minute for the conductive material dispersion at a liquid temperature of 25°C. After measuring at a rotor rotational speed of 6 rpm, the measurement was subsequently carried out at 60 rpm. In the measurement at a rotor rotational speed of 6 rpm, as the rotor, No. 1 was used when the viscosity was less than 1.0 Pa·s, No. 2 when it was 1.0 Pa·s or more and less than 5.0 Pa·s, No. 3 when it was 5.0 Pa·s or more and less than 20 Pa·s, and No. 4 when it was 20 Pa·s or more and less than 100 Pa·s, respectively. In the measurement of the rotor rotation speed of 60 rpm, as the rotor, No. 1 was used when the viscosity was less than 0.1 Pa·s, No. 2 was used when the viscosity was 0.1 Pa·s or more and less than 0.5 Pa·s, No. 3 was used when the viscosity was 0.5 Pa·s or more and less than 2.0 Pa·s, and No. 4 was used when the viscosity was 2.0 Pa·s or more and less than 10 Pa·s, respectively. The viscosity was measured within 5 hours after the completion of the dispersion treatment (hereinafter, this viscosity is referred to as "initial viscosity").

[0180] (TI value) The TI value was calculated from the following formula (1) using the measured viscosity value. Formula (1) TI value = (viscosity measured at 6 rpm / viscosity measured at 60 rpm) [Evaluation criteria] ◎: TI value is 3 or more and 10 or less (best) ○: TI value is 2 or more and less than 3 (good) ×: TI value is less than 2 (bad)

[0181] (Storage stability (S1)) The evaluation of storage stability was carried out by observing the change in viscosity (viscosity change rate) when measured at a rotor rotation speed of 60 rpm after the conductive material dispersion liquid was allowed to stand and stored at 60°C for 10 days. The viscosity change rate was calculated by the following formula (2). Change rate (%) = (viscosity after 10 days at 60°C) / (initial viscosity) × 100 ······ Formula (2) [Evaluation criteria] ◎: Change rate is 85% or more and less than 115% (best) ○: Change rate is 75% or more and less than 85% or 115% or more and less than 125% (good) △: Change rate is 50% or more and less than 75% or 125% or more and less than 150% (acceptable) ×: Change rate is less than 50% or 150% or more (bad)

[0182] (Dispersibility) The evaluation of dispersibility was carried out in accordance with JIS-K5600-2-5 using a grind gauge with a maximum groove depth of 300 μm. The evaluation criteria are as follows. [Evaluation criteria] ○: No coarse particles (best) △: Coarse particles less than 100 μm are present (acceptable) ×: Coarse particles 100 μm or more are present (defective)

[0183] (Conductive R1) The evaluation of conductive R1 was carried out by measuring the conductivity of the coating film applied to a polyethylene terephthalate (PET) film. The conductive material dispersion was applied onto the PET film with a 7-mil applicator, leveled for 10 minutes at 20 °C, and then dried at 100 °C for 20 minutes to obtain a coating film. This coating film was evaluated by measuring the surface resistivity (Ω / □) using a resistivity meter Loresta-GX MCP-T700 (manufactured by Mitsubishi Chemical Analytech Co., Ltd., four-probe method). The evaluation was carried out according to the following criteria. [Evaluation Criteria] ◎: 1.0×10 3 or less (best) 〇: 1.0×10 3 exceeding 1.0×10 4 or less (good) △: 1.0×10 4 exceeding 1.0×10 5 or less (acceptable) ×: 1.0×10 5 exceeding (defective)

[0184] (Brightness L1) The evaluation of brightness L1 was carried out by measuring the brightness L* in the L*a*b* color system of the coating film applied to the PET film using a spectro2guide (spectrophotometer / color difference meter) manufactured by BYK-Gardner, and taking it as brightness L1. The coating film used was the one prepared for the evaluation of conductivity. The evaluation was carried out according to the following criteria [Evaluation Criteria] ◎: 5 or more and 20 or less (best) 〇: 3 or more and less than 5, or exceeding 20 and less than 23 (good) △: 0 or more and less than 3, or 23 or more and less than 25 (acceptable) ×: Less than 0, or 25 or more (defective)

[0185] (Chromaticity b1) For the evaluation of chromaticity b1, for the coating film applied to the PET film, the chromaticity b* in the L*a*b* color system was measured using a spectro2guide (spectrophotometer / color difference meter) manufactured by BYK-Gardner, and defined as chromaticity b1. Note that the same coating film as that prepared for the evaluation of conductivity was used. The evaluation was carried out according to the following criteria. [Evaluation Criteria] ◎: 1 or less (best) 〇: More than 1 and 2 or less (good) △: More than 2 and 3 or less (fair) ×: More than 3 (poor)

[0186] (50% Particle Size (D50)) For the evaluation of the 50% particle size (D50), for the conductive material dispersion, it was measured by the following method using a laser diffraction particle size distribution analyzer (Microtrac MT3000II manufactured by Microtrac Bell), and the evaluation was carried out according to the following evaluation criteria. First, 0.5 g of the conductive material dispersion was diluted with 30 g of water, and then processed with an ultrasonic homogenizer (output 100 W) for 5 minutes to prepare a measurement sample. Next, 1 to 10 drops of the measurement sample were injected into the measurement cell, diluted with a sufficient amount of water, and the particle size distribution was measured at 25°C, and analyzed with a particle refractive index of 1.746 and a solvent refractive index of 1.33. Then, the particle size corresponding to the integrated value of 50% (volume basis) in the obtained particle size distribution was defined as the 50% particle size (D50). [Evaluation Criteria] ◎: 30 μm or more and 130 μm or less (best) 〇: 20 μm or more and less than 30 μm, or more than 130 μm and 140 μm or less (good) △: 10 μm or more and less than 20 μm, or more than 140 μm and 150 μm or less (fair) ×: Less than 10 μm, or more than 150 μm (poor)

[0187] In Examples 1-1 to 1-14, all of the obtained conductive dispersions had good dispersibility, TI values, and storage stability, and also had good conductivity when coated. On the other hand, all of the dispersions obtained in Comparative Examples 1-1 to 1-4 were poor, and it was found that particularly good dispersions could be obtained when using multi-walled carbon nanotubes (A-1) as the carbon-based conductive material (A). In Table 3-2, the places indicated by "-" mean that the dispersions were poor and could not be evaluated. In addition, in Examples 1-1 to 1-14, it was shown that various dispersants can be used as the dispersant (B), and particularly good results were obtained when using a polymer dispersant having an acidic group.

[0188] [Table 3-1]

[0189] [Table 3-2]

[0190] <Production of Conductive Material Dispersion (2)> [Example 2-1] 0.5 part of ATHLOS as multi-walled carbon nanotubes (A-1), 12.5 parts of a 10% by mass neutralized aqueous solution of copolymer B-1, 0.1 part of BYK-024 as an antifoaming agent, and 86.9 parts of purified water were mixed to prepare a mixed solution. At this time, the pH of the mixed solution was 11.7. This mixed solution was dispersed with a colloid mill (magic LAB manufactured by IKA) for 30 minutes, and then subjected to 10 passes of dispersion at an injection pressure of 100 Mpa using a high-pressure homogenizer (Starburst Labo, single nozzle chamber manufactured by Sugino Machine) to obtain a dispersion. Furthermore, 7 parts of 0.1 M acetic acid and 23 parts of purified water were added to this dispersion and mixed with a disperser to obtain 130 parts of a conductive material dispersion (Fb-1). At this time, the pH of the conductive material dispersion (Fb-1) was 9.6.

[0191] [Examples 2-2 to 2-9] The conductive material dispersion liquids Fb-2 to Fb-9 were obtained in the same manner as in Example 2-1, except that the types and amounts of the carbon-based conductive material (A), the dispersant (B), and the dispersion medium (C) were changed to the blending amounts shown in Table 4-1. The blending amount of the dispersant in Table 4-1 is a value in terms of non-volatile content, and the balance of the total amount is water. Also, acetic acid was used as the neutralizing agent (G) to adjust so that the pH before the dispersion treatment (corresponding to the timing of step (a)) and the pH after the dispersion treatment (corresponding to the timing of step (b)) would be the pH values shown in Table 4-2, respectively.

[0192] <Evaluation of Conductive Material Dispersion Liquid (2)> The evaluation of the conductive material dispersion liquid produced in the production of the conductive material dispersion liquid (2) was carried out in the same manner as the evaluation of the conductive material dispersion liquid (1).

[0193] All of the conductive dispersion liquids obtained in Examples 2-1 to 2-9 had good dispersibility, TI values, and storage stability, and also had good conductivity when coated.

[0194]

Table 4-1

[0195]

Table 4-2

[0196] <Production of Conductive Material Dispersion Liquid (3)> [Example 3-1] 0.5 part of ATHLOS as the multi-walled carbon nanotube (A-1), 25 parts of a 10 mass% neutralized aqueous solution of the copolymer B-1, 0.1 part of BYK-024 as an antifoaming agent, and 74.4 parts of purified water were mixed to prepare a mixed liquid. At this time, the pH of the mixed liquid was 12.1. This mixed solution was subjected to dispersion treatment with a colloid mill (IKA magic LAB) for 30 minutes to obtain a dispersion. To 100 parts of this dispersion, 15 parts of 0.1 M acetic acid and 15 parts of purified water were further added and mixed with a disperser to obtain a conductive material dispersion (Fc-1). At this time, the pH of the conductive material dispersion (Fc-1) was 9.1.

[0197] [Example 3-2] 0.5 part of ATHLOS as the multi-walled carbon nanotube (A-1), 25 parts of a 10% by mass neutralized aqueous solution of the copolymer B-1, 0.1 part of BYK-024 as an antifoaming agent, and 74.4 parts of purified water were mixed to prepare a mixed solution. At this time, the pH of the mixed solution was 12.1. This mixed solution was subjected to ultrasonic dispersion treatment with an ultrasonic disperser (hielscher UP400S) for 30 minutes to obtain a dispersion. To 100 parts of this dispersion, 15 parts of 0.1 M acetic acid and 15 parts of purified water were further added and mixed with a disperser to obtain a conductive material dispersion (Fc-2). At this time, the pH of the conductive material dispersion (Fc-2) was 9.0.

[0198] [Example 3-3] 0.5 part of ATHLOS as the multi-walled carbon nanotube (A-1), 25 parts of a 10% by mass neutralized aqueous solution of the copolymer B-1, 0.1 part of BYK-024 as an antifoaming agent, and 74.4 parts of purified water were mixed to prepare a mixed solution. At this time, the pH of the mixed solution was 12.1. 200 g of zirconia beads with a diameter of 0.5 mm were charged as a dispersion medium into this mixed solution, and dispersion treatment was carried out with a paint shaker for 8 hours to obtain a dispersion. To 100 parts of this dispersion, 15 parts of 0.1 M acetic acid and 15 parts of purified water were further added and mixed with a disperser to obtain a conductive material dispersion (Fc-3). At this time, the pH of the conductive material dispersion (Fc-3) was 8.9.

[0199] [Example 3-4] As the multi-walled carbon nanotube (A-1), 0.5 part of ATHLOS was used, 25 parts of a 10% by mass neutralized aqueous solution of copolymer B-1, 0.1 part of BYK-024 as an antifoaming agent, and 74.4 parts of purified water were mixed to prepare a mixed solution. At this time, the pH of the mixed solution was 12.1. This mixed solution was subjected to dispersion treatment with a colloid mill (magic LAB manufactured by IKA) for 30 minutes to obtain a dispersion. To 100 parts of this dispersion, 28 parts of purified water was further added and mixed with a disper to obtain 130 parts of a conductive material dispersion (Fc-4). At this time, the pH of the conductive material dispersion (Fc-4) was 11.7.

[0200] [Example 3-5] As the dispersant (B), 2 parts of copolymer B-1, as the neutralizing agent (G), 10 parts of acetic acid, and 97.3 parts of purified water were stirred at 25 °C and a disper rotation speed of 500 rpm for 15 minutes. To this neutralized solution, 0.5 part of ATHLOS as the multi-walled carbon nanotube (A-1) and 0.1 part of BYK-024 as an antifoaming agent were mixed to prepare a mixed solution. At this time, the pH of the mixed solution was 6.8. This mixed solution was subjected to dispersion treatment with a colloid mill (magic LAB manufactured by IKA) for 30 minutes to obtain a dispersion. To 100 parts of this dispersion, 3 parts of 0.1 M acetic acid and 27 parts of purified water were further added and mixed with a disper to obtain 130 parts of a conductive material dispersion (Fc-5). At this time, the pH of the conductive material dispersion (Fc-5) was 5.8.

[0201] Note that the blending amount of the dispersant in Table 5-1 is the value in terms of non-volatile content, and the balance of the total amount is water.

[0202] <Evaluation of Conductive Material Dispersion (3)> The evaluation of the conductive material dispersion liquid produced in the production of the conductive material dispersion liquid (3) was carried out in the same manner as the evaluation of the conductive material dispersion liquid (1), except for the following points. That is, the test method of the storage stability test was changed to a method of visually evaluating the separation state of the dispersion liquid when the prepared conductive material dispersion liquid was placed in a vial and left standing at 40 °C for 10 days. Hereinafter, the storage stability test carried out by this method is referred to as the storage stability test (S2). The storage stability test (S2) was evaluated according to the following criteria. [Evaluation Criteria] 〇: No change (good) △: The supernatant is transparent. (Acceptable) ×: Sedimentation or separation (unacceptable)

[0203] All of the conductive dispersions obtained in Examples 3-1 to 3-5 had good dispersibility, TI value, and storage stability, and also had good conductivity when coated. From Examples 3-1 to 3-4, it can be seen that particularly good dispersions can be obtained when a rotor-stator type disperser, an ultrasonic disperser, and a high-pressure homogenizer are used as the disperser. Also, from Examples 3-1 and 3-4 to 3-5, it was found that a particularly good dispersion state can be obtained by having step (a).

[0204]

Table 5-1

[0205]

Table 5-2

[0206] Manufacture of a conductive material dispersion liquid and a conductive film containing resin (E) (1) [Example 4-1] The conductive material dispersion liquid Fa-1, clear paint A, and purified water obtained in Example 1-1 were blended as follows to obtain a conductive material dispersion liquid containing resin (E). Conductive material dispersion liquid Fa-1: 3.64 parts Clear paint A = (aqueous cloudy clear / simel 325 = 75% by mass / 25% by mass): 10 parts Purified water: 1.08 parts Subsequently, the obtained conductive material dispersion liquid containing resin (E) was applied to a corona-discharged PET film with an applicator so that the film thickness became 20 ± 2 μm, leveled for 30 minutes, dried at 60°C for 30 minutes, and then baked at 140°C for 20 minutes to obtain a conductive film Pa-1.

[0207] [Examples 4-2 to 4-11, Comparative Examples 4-1 to 4-3] Conductive films Pa-2 to Pa-11 and Pb-1 to Pb-3 were obtained in the same manner as in Example 4-1, except that the types and amounts of the conductive material dispersion, clear paint A, and purified water were changed as shown in Table 6.

[0208] (Evaluation of Conductive Film (1)) The evaluation of the conductive film prepared in the production of the conductive material dispersion containing resin (E) and the conductive film (1) was carried out by the following method.

[0209] (Compatibility) Compatibility was evaluated by measuring the haze value (Hz) of the prepared conductive film using NDH8000 (manufactured by Nippon Denshoku Industries Co., Ltd.). The evaluation was carried out according to the following criteria. [Evaluation Criteria] 〇: Less than 5 △: 5 or more and less than 10 ×: 10 or more

[0210] (Transparency) Transparency was evaluated by measuring the total light transmittance (TT) of the prepared conductive film using a haze meter NDH8000 (manufactured by Nippon Denshoku Industries Co., Ltd.). The evaluation was carried out according to the following criteria. [Evaluation Criteria] ◎: 40 or more (best) 〇: 35 or more and less than 40 (good) △: 30 or more and less than 35 (fair) ×: Less than 30 (poor)

[0211] (Conductivity R2) Conductivity R2 was evaluated by measuring the surface resistivity (Ω / □) of the prepared conductive film using a resistivity meter Hi-Rester UX MCP-HT800 (manufactured by Mitsubishi Chemical Corporation). The evaluation was carried out according to the following criteria. [Evaluation Criteria] ◎: 1.0×10 6 Less than (best) 〇: 1.0×10 6 or more and 1.0×10 8 Less than (good) △: 1.0×108 Less than 1.0×10 10 (acceptable) ×: 1.0×10 10 or more (defective)

[0212] All of the conductive films obtained in Examples 4-1 to 4-11 had good compatibility, transparency, and conductivity. On the other hand, all of the conductive films obtained in Comparative Examples 4-1 to 4-3 were defective, and it was found that a particularly good conductive film could be obtained when using the multi-walled carbon nanotube (A-1) as the carbon-based conductive material (A).

[0213]

Table 6

[0214] (2) Production of Conductive Material Dispersion Liquid and Conductive Film Containing Resin (E) [Example 5-1] The conductive material dispersion liquid Fa-7, dispersion medium (C), and resin (E) obtained in Example 1-7 were blended as follows to obtain a conductive material dispersion liquid containing resin (E). Conductive material dispersion liquid Fa-7: 8.2 parts Dispersion medium (C): Water 9.1 parts Resin (E): NANOCRYL-S KPX-02-014 10 parts Subsequently, the obtained conductive material dispersion liquid containing resin (E) was applied to a corona-discharge-treated PET film with an applicator so that the film thickness became 20 ± 2 μm, leveled for 30 minutes, dried at 60°C for 30 minutes, and then baked at 140°C for 20 minutes to obtain a conductive film Pc-1.

[0215] [Examples 5-2 to 5-8] Conductive films Pc-2 to Pc-8 were obtained in the same manner as in Example 5-1, except that the types and amounts of the conductive material dispersion liquid, dispersion medium (C), and resin (E) were changed as shown in Table 7. In Table 7, the places indicated by "-" mean that the non-conductive particles (F) were not added.

[0216] [Example 5-9] The conductive material dispersion liquid Fa-7, dispersion medium (C), resin (E), and non-conductive particles (F) obtained in Examples 1-7 were blended as follows to obtain a conductive material dispersion liquid containing resin (E) and non-conductive particles (F). Conductive material dispersion liquid Fa-7: 7.6 parts Dispersion medium (C): Water 7.7 parts Resin (E): Takelac W-6110 10 parts Non-conductive particles (F): NK-8G 0.5 parts Subsequently, the obtained conductive material dispersion liquid containing resin (E) and non-conductive particles (F) was applied to a corona-discharged PET film with an applicator so that the film thickness became 20 ± 2 μm, leveled for 30 minutes, dried at 60°C for 30 minutes, and then baked at 140°C for 20 minutes to obtain a conductive film Pc-9.

[0217] [Examples 5-10 to 5-13] Conductive films Pc-10 to Pc-13 were obtained in the same manner as in Example 5-9, except that the types and amounts of the conductive material dispersion liquid, dispersion medium (C), resin (E), and non-conductive particles (F) were changed as shown in Table 7.

[0218] All of the conductive material dispersion liquids obtained in Examples 5-1 to 5-13 were easy to mix, and their viscosity and storage stability were not impaired after mixing, and they were in good condition. Also, all of the conductive films obtained in Examples 5-1 to 5-13 had good appearance. From these results, it can be seen that various resins and non-conductive particles can be blended and used for the conductive material dispersion liquid.

[0219]

Table 7

Claims

1. A conductive material dispersion liquid containing a carbon-based conductive material (A), a dispersant (B) and a dispersion medium (C), The carbon-based conductive material (A) contains a multi-walled carbon nanotube (A-1) having a branched structure, The iron content in the branched multi-walled carbon nanotube (A-1) is more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum is 0 mass% or more and 0.1 mass% or less, The conductive material dispersion contains a dispersant (B) selected from the group consisting of (meth)acrylic dispersants, polyurethane dispersants, urethane acrylate dispersants, polyether dispersants, polyester dispersants, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, modified rosin compounds, cellulose compounds, styrene block copolymers, and styrene-acrylic acid copolymers (excluding fluoropolymers having a hydroxyl group- or carbonyl group-containing group that contains a unit based on fluoroolefin).

2. The specific surface area of ​​the branched multi-walled carbon nanotube (A-1) is 400 m ２ The conductive material dispersion according to claim 1 , wherein the average molecular weight of the conductive material dispersion is 1 / g or less.

3. 2. The conductive material dispersion according to claim 1, wherein the average aspect ratio of the branched multi-walled carbon nanotubes (A-1) is 300 or more and 2000 or less.

4. 2. The conductive material dispersion according to claim 1, wherein the average outer diameter of the branched multi-walled carbon nanotubes (A-1) is 5 nm or more and 30 nm or less.

5. The conductive material dispersion according to claim 1, wherein the content of the multi-walled carbon nanotubes (A-1) having a branched structure is 0.01% by mass or more and 5% by mass or less based on 100% by mass of the non-volatile matter of the conductive material dispersion.

6. The conductive material dispersion according to any one of claims 1 to 5, wherein the conductive material dispersion has a thixotropic index of 2 or more and 10 or less.

7. The conductive material dispersion according to any one of claims 1 to 5, wherein the conductive material dispersion has a D50 particle size of 10 µm or more and 150 µm or less.

8. The conductive material dispersion according to any one of claims 1 to 5, further comprising a resin (E).

9. The conductive material dispersion according to any one of claims 1 to 5, further comprising non-conductive particles (F).

10. The conductive material dispersion according to claim 8, wherein the content of the carbon-based conductive material (A) is 0.01% by mass or more and 3% by mass or less in 100% by mass of the nonvolatile content of the conductive material dispersion.

11. A conductive film containing a carbon-based conductive material (A), a dispersant (B) and a resin (E), The carbon-based conductive material (A) contains a multi-walled carbon nanotube (A-1) having a branched structure, The iron content in the branched multi-walled carbon nanotube (A-1) is more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum is 0 mass% or more and 0.1 mass% or less, The conductive film contains the dispersant (B) selected from the group consisting of (meth)acrylic dispersants, polyurethane dispersants, urethane acrylate dispersants, polyether dispersants, polyester dispersants, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, modified rosin compounds, cellulose compounds, styrene block copolymers, and styrene-acrylic acid copolymers (excluding fluoropolymers having a hydroxyl group- or carbonyl group-containing group that contains a unit based on fluoroolefin).

12. The conductive film according to claim 11 , wherein the resin (E) is a binder resin.

13. A method for producing a conductive material dispersion liquid obtained by dispersing a mixture containing a carbon-based conductive material (A), a dispersant (B) and a dispersion medium (C) with a media-less disperser selected from the group consisting of a rotor-stator type disperser, an ultrasonic disperser and a high-pressure homogenizer, comprising: The carbon-based conductive material (A) contains a multi-walled carbon nanotube (A-1) having a branched structure, The iron content in the branched multi-walled carbon nanotube (A-1) is more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum is 0 mass% or more and 0.1 mass% or less, The method for producing a conductive material dispersion liquid includes the dispersant (B) selected from the group consisting of (meth)acrylic dispersants, polyurethane dispersants, urethane acrylate dispersants, polyether dispersants, polyester dispersants, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, modified rosin compounds, cellulose compounds, styrene block copolymers, and styrene-acrylic acid copolymers (excluding fluoropolymers that contain units based on fluoroolefin and have a hydroxyl group- or carbonyl group-containing group).

14. A method for producing a conductive material dispersion liquid containing a carbon-based conductive material (A), a dispersant (B) and a dispersion medium (C), comprising the steps of: The carbon-based conductive material (A) contains a multi-walled carbon nanotube (A-1) having a branched structure, The iron content in the branched multi-walled carbon nanotube (A-1) is more than 0 mass% and 5 mass% or less, and the total content of cobalt and molybdenum is 0 mass% or more and 0.1 mass% or less, The method for producing a conductive material dispersion liquid includes the following step (a), in which the dispersant (B) is a dispersant selected from the group consisting of a (meth)acrylic dispersant, a polyurethane dispersant, a urethane acrylate dispersant, a polyether dispersant, a polyester dispersant, polyvinyl alcohol, polyvinyl acetal, polyvinylpyrrolidone, a modified rosin compound, a cellulose compound, a styrene block copolymer, and a styrene-acrylic acid copolymer (excluding fluoropolymers having a hydroxyl group- or carbonyl group-containing group that contains a unit based on fluoroolefin): Step (a): A step of mixing a carbon-based conductive material (A), a dispersant (B) and a dispersion medium (C) to prepare a mixed liquid, and then dispersing the mixed liquid at a pH of 7 or more.

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