Conductive agent dispersion liquid

Abstract

In a conductive agent dispersion containing polymer (A), a carbon-based conductive agent (B), and a liquid medium (C), polymer (A) comprises repeating units (a1) from aromatic vinyl compounds and repeating units (a2) from unsaturated carboxylic acid ester compounds. The proportion of repeating units (a1) relative to the total number of repeating units contained in polymer (A) is 1–50% by mass, and the proportion of repeating units (a2) relative to the total number of repeating units contained in polymer (A) is 20–75% by mass. The viscosity of a polymer solution obtained by dissolving polymer (A) in N-methyl-2-pyrrolidone at a solid content concentration of 8% by mass is 300–5000 mPa·s as measured at 25°C.

Description

Technical Field

[0001] [Cross-references to related applications]

[0002] This application claims priority based on Japanese Patent Application No. 2023-203856, filed on December 1, 2023, the entire contents of which are incorporated herein by reference.

[0003] This disclosure relates to conductive agent dispersions, and more specifically, to conductive agent dispersions formed by dispersing carbon-based conductive agents in a liquid medium. Background Technology

[0004] Carbon nanotubes (hereinafter also known as "CNTs"), carbon nanofibers, furnace black, acetylene black, and other carbon-based conductive agents are materials with excellent electrical conductivity, thermal conductivity, and mechanical properties, and are also lightweight and tough. It is expected that these carbon-based conductive agents with such excellent properties will be used in a wide range of industrial applications.

[0005] Carbon-based conductive agents typically exhibit high cohesion but poor dispersibility. Furthermore, when applied to various applications, the excellent properties of carbon-based conductive agents cannot be fully utilized in their aggregated state. Therefore, conventional methods have involved preparing suspensions (slurries) by dispersing carbon-based conductive agents in a liquid medium, coating the suspension containing the carbon-based conductive agent onto a substrate, removing the liquid medium, or mixing the suspension with a matrix material (such as resin or rubber).

[0006] Various methods have been proposed for dispersing carbon-based conductive agents in a liquid medium, namely, adding a polymer as a dispersant together with the carbon-based conductive agent to the liquid medium, thereby improving the dispersibility of the carbon-based conductive agent in the liquid medium (see, for example, Patent Document 1). Patent Document 1 discloses improving the dispersibility of conductive additives by preparing a dispersion containing a conductive additive, a liquid medium, and polyimide having a steroidal or mesocrystalline structure.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2022-116646 Summary of the Invention

[0010] In developing products that utilize carbon-based conductive agents, it is considered important to improve the dispersibility of the carbon-based conductive agents and to maximize the extraction of the various properties of the carbon-based conductive agents in a variety of applications.

[0011] This disclosure was made to solve the above-mentioned problems, and its main objective is to provide a conductive agent dispersion with excellent dispersibility of carbon-based conductive agents.

[0012] According to this disclosure, in one aspect, a conductive agent dispersion is provided, comprising a polymer (A), a carbon-based conductive agent (B), and a liquid medium (C). The polymer (A) comprises repeating units (a1) from an aromatic vinyl compound and repeating units (a2) from an unsaturated carboxylic acid ester compound. The proportion of repeating units (a1) is 1 to 50% by mass relative to the total number of repeating units contained in the polymer (A), and the proportion of repeating units (a2) is 20 to 75% by mass relative to the total number of repeating units contained in the polymer (A). The polymer solution obtained by dissolving the polymer (A) in N-methyl-2-pyrrolidone at a solid content concentration of 8% by mass has a viscosity of 300 to 5000 mPa·s measured at 25°C.

[0013] According to this disclosure, a conductive agent dispersion with excellent dispersibility of carbon-based conductive agents can be obtained. Detailed Implementation

[0014] The embodiments of this disclosure will now be described in detail. It should be noted that the present invention is not limited to the embodiments described below, but should be understood to include various modifications implemented without changing the spirit of the invention.

[0015] It should be noted that in this specification, "(meth)acrylamide" is a term that includes both "acrylamide" and "methacrylamide," and "(meth)acrylic acid" is a term that includes both "acrylic acid" and "methacrylic acid." "(meth)acrylate" is a term that includes both "acrylate" and "methacrylate." Numerical ranges such as "X~Y" are interpreted as ranges that include the value X as the lower limit and the value Y as the upper limit.

[0016] The conductive agent dispersion disclosed herein is a dispersion formed by dispersing a carbon-based conductive agent in a liquid medium. The conductive agent dispersion of this disclosure comprises: a polymer (hereinafter also referred to as "polymer (A)") containing repeating units from aromatic vinyl compounds and repeating units from unsaturated carboxylic acid ester compounds, a carbon-based conductive agent, and a liquid medium. The components contained in the conductive agent dispersion of this disclosure will be described in detail below.

[0017] <Polymer (A)>

[0018] Polymer (A) is a component that improves the liquid dispersibility of carbon-based conductive agents in liquid media. Carbon-based conductive agents have high cohesive forces (van der Waals forces), making them difficult to disperse uniformly in liquid media. Furthermore, when the dispersion of the carbon-based conductive agent is poor, there are concerns that the various properties of the conductive agent may not be fully utilized in articles obtained using this conductive agent dispersion. From this perspective, the conductive agent dispersion of this disclosure, by containing polymer (A) along with the carbon-based conductive agent, achieves excellent dispersibility of the carbon-based conductive agent in liquid media.

[0019] Polymer (A) comprises repeating units derived from aromatic vinyl compounds (hereinafter also referred to as "repeating units (a1)") and repeating units derived from unsaturated carboxylic acid ester compounds (hereinafter also referred to as "repeating units (a2)"). In addition, polymer (A) may further comprise repeating units different from repeating units (a1) and repeating units (a2) (hereinafter also referred to as "other repeating units").

[0020] (Repeating unit (a1))

[0021] Examples of aromatic vinyl compounds providing the repeating unit (a1) include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 4-tert-butylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, vinyltoluene, 4-ethylstyrene, chlorostyrene, and divinylbenzene. Among these, styrene is particularly preferred as the aromatic vinyl compound providing the repeating unit (a1). It should be noted that the aromatic vinyl compound providing the repeating unit (a1) can be one or more.

[0022] The proportion of repeating units (a1) in polymer (A) relative to the total amount of repeating units (100% by mass) in polymer (A) is 1 to 50% by mass. If the proportion of repeating units (a1) in polymer (A) is less than 1% by mass or more than 50% by mass, the polymer (A) tends to aggregate in the dispersion containing the carbon-based conductive agent and polymer (A), resulting in a tendency for the dispersibility of the carbon-based conductive agent to deteriorate. From the viewpoint of improving the dispersibility of the carbon-based conductive agent by suppressing the fusion of polymers (A), the proportion of repeating units (a1) relative to the total amount of repeating units in polymer (A) is preferably 15% by mass or more, more preferably 20% by mass or more. In addition, the proportion of repeating units (a1) relative to the total amount of repeating units in polymer (A) is preferably 45% by mass or less, more preferably 40% by mass or less.

[0023] The preferred range of the proportion of repeating units (a1) in polymer (A) can be determined by appropriately combining the above-mentioned upper and lower limits. Specifically, the proportion of repeating units (a1) relative to the total amount of repeating units contained in polymer (A) is preferably 15 to 50% by mass, more preferably 15 to 45% by mass, and even more preferably 20 to 40% by mass.

[0024] (Repeated unit (a2))

[0025] Examples of unsaturated carboxylic acid ester compounds that provide the repeating unit (a2) include (meth)acrylate compounds, itaconic acid ester compounds, fumarate compounds, and maleate compounds. Among these, the unsaturated carboxylic acid ester compound may preferably be selected from one or more of (meth)acrylate compounds and itaconic acid ester compounds.

[0026] Examples of (meth)acrylate compounds include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, di(meth)acrylate, ethylene glycol di(meth)acrylate, etc. Propylene glycol acrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, allyl acrylate, hydroxymethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 5-hydroxypentyl acrylate, 6-hydroxyhexyl acrylate, glyceryl monomethacrylate, and glyceryl dimethacrylate, etc.

[0027] Specific examples of itaconic acid ester compounds include dimethyl itaconic acid, diethyl itaconic acid, dipropyl itaconic acid, and dibutyl itaconic acid. The unsaturated carboxylic acid ester compound providing the repeating unit (a2) can be one or more.

[0028] It should be noted that the unsaturated carboxylic acid ester compound providing the repeating unit (a2) does not have either a carboxyl group or a sulfonic acid group. In this specification, repeating units from unsaturated carboxylic acid ester compounds having a carboxyl group (e.g., unsaturated dicarboxylic acid monoesters, etc.) are classified as repeating units (a3). Additionally, repeating units from unsaturated carboxylic acid ester compounds having a sulfonic acid group (e.g., (meth)acrylate sulfonyl ethyl ester, etc.) are classified as repeating units (a5).

[0029] Among these, the unsaturated carboxylic acid ester compound providing the repeating unit (a2) is preferably selected from one or more of chain-like unsaturated carboxylic acid ester compounds and alicyclic unsaturated carboxylic acid ester compounds, more preferably selected from one or more of alkyl (meth)acrylate, alicyclic esters of (meth)acrylate, hydroxyalkyl (meth)acrylate, and dialkyl itaconic acid esters. Specifically, it is preferably selected from one or more of methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, ethylene glycol di(meth)acrylate, 2-hydroxyethyl (meth)acrylate, dimethyl itaconic acid, diethyl itaconic acid, and dibutyl itaconic acid.

[0030] The proportion of repeating units (a2) in polymer (A) is 20-75% by mass relative to the total number of repeating units in polymer (A). If the proportion of repeating units (a2) in polymer (A) is less than 20% by mass or more than 75% by mass, the affinity between polymer (A) and the liquid medium cannot be sufficiently ensured, resulting in poor dispersibility of the carbon-based conductive agent. From the viewpoint of improving the affinity between polymer (A) and the liquid medium and improving the dispersibility of the carbon-based conductive agent in the liquid medium, the proportion of repeating units (a2) relative to the total number of repeating units in polymer (A) is preferably 23% by mass or more, more preferably 25% by mass or more. Furthermore, the proportion of repeating units (a2) relative to the total number of repeating units in polymer (A) is preferably 70% by mass or less, more preferably 65% ​​by mass or less.

[0031] The preferred range of the proportion of repeating unit (a2) in polymer (A) can be determined by appropriately combining the above-mentioned upper and lower limits. Specifically, the proportion of repeating unit (a2) relative to the total amount of repeating units contained in polymer (A) is preferably 23 to 75% by mass, more preferably 23 to 70% by mass, and even more preferably 25 to 65% by mass.

[0032] (Other repeating units)

[0033] The polymer (A) may contain other repeating units, as long as they are derived from monomers capable of copolymerizing with the aromatic vinyl compound providing the repeating unit (a1) and the unsaturated carboxylic acid ester compound providing the repeating unit (a2), without particular limitation. Specific examples of other repeating units include repeating units derived from unsaturated carboxylic acids (hereinafter also referred to as "repeating unit (a3)"), repeating units derived from α,β-unsaturated nitrile compounds (hereinafter also referred to as "repeating unit (a4)"), repeating units derived from compounds having sulfonic acid groups (hereinafter also referred to as "repeating unit (a5)"), repeating units derived from (meth)acrylamide (hereinafter also referred to as "repeating unit (a6)"), repeating units derived from conjugated diene compounds (hereinafter also referred to as "repeating unit (a7)"), etc.

[0034] • Repeating unit (a3)

[0035] Examples of unsaturated carboxylic acids that provide the repeating unit (a3) ​​include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; and monoesters of dicarboxylic acids such as maleic acid monoester, fumaric acid monoester, and itaconic acid monoester. Examples of unsaturated carboxylic anhydrides that provide the repeating unit (a3) ​​include the anhydrides of the dicarboxylic acids exemplified above. There may be one or more unsaturated carboxylic acids and anhydrides that provide the repeating unit (a3).

[0036] Among these, the unsaturated carboxylic acid or unsaturated carboxylic anhydride that provides the repeating unit (a3) ​​is preferably selected from one or more of acrylic acid, methacrylic acid, itaconic acid, monomethyl itaconic acid, monoethyl itaconic acid, and monobutyl itaconic acid.

[0037] When a repeating unit (a3) ​​is introduced into polymer (A), the proportion of the repeating unit (a3) ​​in polymer (A) relative to the total amount of repeating units contained in polymer (A) is preferably 10% by mass or less. By setting the proportion of the repeating unit (a3) ​​in polymer (A) within the above range, there is a tendency to improve the dispersibility of the carbon-based conductive agent. From the viewpoint of improving the dispersibility of the carbon-based conductive agent, the proportion of the repeating unit (a3) ​​relative to the total amount of repeating units contained in polymer (A) is more preferably 0.5 to 10% by mass. Furthermore, the proportion of the repeating unit (a3) ​​relative to the total amount of repeating units contained in polymer (A) is more preferably 0.7% by mass or more, and even more preferably 1% by mass or more. Moreover, the proportion of the repeating unit (a3) ​​relative to the total amount of repeating units contained in polymer (A) is more preferably 8% by mass or less, and even more preferably 7% by mass or less.

[0038] • Repeating unit (a4)

[0039] Examples of α,β-unsaturated nitrile compounds providing the repeating unit (a4) include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile, isopropylene malononitrile (ethylene vinylidene), fumaric acid, and tetracyanoethylene. The α,β-unsaturated nitrile compound providing the repeating unit (a4) can be one or more. From the viewpoint of ease of acquisition, the α,β-unsaturated nitrile compound providing the repeating unit (a4) preferably includes one or both of acrylonitrile and methacrylonitrile, and more preferably includes acrylonitrile.

[0040] When a repeating unit (a4) is introduced into polymer (A), the proportion of the repeating unit (a4) in polymer (A) relative to the total amount of repeating units contained in polymer (A) is preferably 5 to 40% by mass. By setting the proportion of the repeating unit (a4) in polymer (A) within the above range, the polymer (A) exhibits good affinity with the liquid medium, resulting in a tendency to improve the dispersibility of the carbon-based conductive agent. From the viewpoint of improving the dispersibility of the carbon-based conductive agent, the proportion of the repeating unit (a4) relative to the total amount of repeating units contained in polymer (A) is more preferably 6% by mass or more, and even more preferably 7% by mass or more. Furthermore, the proportion of the repeating unit (a4) relative to the total amount of repeating units contained in polymer (A) is more preferably 37% by mass or less, and even more preferably 35% by mass or less.

[0041] • Repeating unit (a5)

[0042] Examples of compounds containing a sulfonic acid group that provide the repeating unit (a5) (hereinafter also referred to as "sulfonic acid-containing compounds") include, for example, vinylsulfonic acid, styrenesulfonic acid, allylsulfonic acid, sulfonyl ethyl (meth)acrylate, sulfonyl propyl (meth)acrylate, sulfonyl butyl (meth)acrylate, 2-acrylamido-2-methylpropanesulfonic acid, 2-hydroxy-3-acrylamidopropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, and their alkali metal salts. The sulfonic acid-containing compound providing the repeating unit (a5) may be one or more compounds.

[0043] Among these, the sulfonic acid-containing compound providing the repeating unit (a5) is preferably selected from at least one of vinyl monomers and styrene monomers. Specifically, it is preferably selected from at least one of vinyl sulfonic acid, styrene sulfonic acid, and allyl sulfonic acid.

[0044] When a repeating unit (a5) is introduced into polymer (A), the proportion of the repeating unit (a5) in polymer (A) relative to the total amount of repeating units contained in polymer (A) is preferably 0.1 to 10% by mass. By setting the proportion of the repeating unit (a5) in polymer (A) within the above range, there is a tendency to improve the dispersibility of the carbon-based conductive agent. From the viewpoint of improving the dispersibility of the carbon-based conductive agent, the proportion of the repeating unit (a5) relative to the total amount of repeating units contained in polymer (A) is more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, the proportion of the repeating unit (a5) relative to the total amount of repeating units contained in polymer (A) is more preferably 8% by mass or less, and even more preferably 7% by mass or less.

[0045] • Repeating unit (a6)

[0046] Examples of (meth)acrylamide compounds providing the repeating unit (a6) include acrylamide, methacrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethylmethacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, N-hydroxymethylacrylamide, N-hydroxymethylmethacrylamide, diacetoneacrylamide, maleic acid monoacrylamide, etc. The (meth)acrylamide compound providing the repeating unit (a6) can be one or more. Among these, the (meth)acrylamide compound is preferably one or both of acrylamide and methacrylamide.

[0047] When a repeating unit (a6) is introduced into polymer (A), the proportion of the repeating unit (a6) in polymer (A) relative to the total amount of repeating units contained in polymer (A) is preferably 10% by mass or less. By setting the proportion of the repeating unit (a6) in polymer (A) within the above range, there is a tendency to improve the dispersibility of the carbon-based conductive agent. From the viewpoint of improving the dispersibility of the carbon-based conductive agent, the proportion of the repeating unit (a6) relative to the total amount of repeating units contained in polymer (A) is more preferably 0.1 to 10% by mass. Furthermore, the proportion of the repeating unit (a6) relative to the total amount of repeating units contained in polymer (A) is more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more. Moreover, the proportion of the repeating unit (a6) relative to the total amount of repeating units contained in polymer (A) is more preferably 8% by mass or less, and even more preferably 7% by mass or less.

[0048] (Physical properties of polymer (A))

[0049] Viscosity

[0050] Polymer (A) is a polymer with a large molecular weight and high viscosity. Specifically, the viscosity of a polymer solution obtained by dissolving polymer (A) in N-methyl-2-pyrrolidone (NMP) at a solid content concentration of 8% by mass (hereinafter also referred to as "8% NMP viscosity") measured at 25°C is 300 to 5000 mPa·s. If the 8% NMP viscosity of the polymer is less than 300 mPa·s or greater than 5000 mPa·s, the dispersibility of the carbon-based conductive agent is poor, and the carbon-based conductive agent becomes an uneven slurry. From the viewpoint of sufficiently improving the dispersibility of the carbon-based conductive agent, the 8% NMP viscosity of polymer (A) is preferably 350 mPa·s or more, and more preferably 500 mPa·s or more. In addition, the 8% NMP viscosity of polymer (A) is preferably 4500 mPa·s or less, and more preferably 4000 mPa·s or less. It should be noted that the 8% NMP viscosity of polymer (A) is a value measured at 25°C using a type B viscometer in accordance with JIS Z 8803 2011.

[0051] The preferred range of the 8% NMP viscosity of polymer (A) can be determined by appropriately combining the above-mentioned upper and lower limits. Specifically, the 8% NMP viscosity of polymer (A) is preferably 350–5000 mPa·s, more preferably 350–4500 mPa·s, and even more preferably 500–4000 mPa·s.

[0052] • Weight-average molecular weight (Mw)

[0053] The Mw of polymer (A) is preferably between 2,000 and 10,000,000. If the Mw of polymer (A) is within this range, the adsorption stability of polymer (A) to the carbon-based conductive agent can be improved, and the dispersibility of the carbon-based conductive agent in the liquid medium can be ensured. Thus, the dispersibility of the carbon-based conductive agent in the liquid medium can be improved. From the viewpoint of achieving excellent dispersibility of the carbon-based conductive agent, the Mw of polymer (A) is more preferably 5,000 or more, and even more preferably 50,000 or more. Furthermore, the Mw of polymer (A) is more preferably 5,000,000 or less, and even more preferably 1,000,000 or less. It should be noted that the Mw of polymer (A) is a polystyrene conversion value determined by gel permeation chromatography (GPC).

[0054] The details of the method for determining the Mw of polymer (A) are as follows.

[0055] 10 mg of polymer (A) with a solid content of 20% by mass was mixed with 5 mL of THF and incubated at 25°C for 16 hours. The mixture containing polymer (A) was then passed through a 0.45 μm membrane filter as the assay sample. Using the assay sample, the weight-average molecular weight (Mw) of the dissolved THF component was determined according to the following assay conditions based on GPC-based polystyrene conversion (RI detection).

[0056] [Measurement Conditions]

[0057] Temperature: 35℃

[0058] Solvent: THF

[0059] Flow rate: 1.0 mL / min

[0060] Concentration: 0.2% by mass

[0061] Test sample injection volume: 100 μL

[0062] [column]

[0063] The test was performed using Tosoh GPC TSKgel α-2500 (30cm x 2 tubes). It should be noted that the determination was performed under conditions where the linear correlation between Log10(Mw) and elution time was 0.98 or higher, within the range of Mw 1000–20000000.

[0064] (Method for manufacturing polymer (A))

[0065] The method for manufacturing polymer (A) is not particularly limited. As a method for manufacturing polymer (A), emulsion polymerization using an aqueous medium as the polymerization medium is preferred. As emulsion polymerization, known methods can be applied. Specifically, for example, a method can be used whereby the monomer is dispersed in an aqueous medium (preferably water) in the presence of an emulsifier, polymerization is carried out in the presence of a polymerization initiator, and after reaching the desired polymerization conversion, a polymerization terminator is added to terminate the polymerization.

[0066] Examples of emulsifiers include anionic surfactants, nonionic surfactants, and amphoteric surfactants. Anionic surfactants are typically used to obtain stable emulsion dispersions. Examples of anionic surfactants include long-chain fatty acid salts with 10 or more carbon atoms, rosin salts, and benzene sulfonates containing straight-chain alkyl groups. Specifically, examples include potassium and sodium salts of decanoic acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, octylbenzenesulfonic acid, dodecylbenzenesulfonic acid, dodecyl diphenyl ether sulfonic acid, and dodecyl diphenyl ether disulfonic acid. Fluorinated surfactants can also be used. One type or two or more types can be used as emulsifiers.

[0067] As polymerization initiators, free radical polymerization initiators commonly used in emulsion polymerization can be used. Examples of polymerization initiators include organic peroxides such as benzoyl peroxide, lauroyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, pinane hydroperoxide, paramenthane hydroperoxide, trimethylbicycloheptyl hydroperoxide, di-tert-butyl peroxide, and dicumyl peroxide. Additionally, diazo compounds such as azobisisobutyronitrile, inorganic peroxides such as potassium persulfate, and redox catalysts such as combinations of these peroxides and ferrous sulfate can also be used. One type of polymerization initiator can be used alone, or two or more can be used in combination. The amount of polymerization initiator used is typically 0.01 parts by mass or more, preferably 0.05 to 1.0 parts by mass, relative to 100 parts by mass of the total monomers used in the polymerization.

[0068] During polymerization, chain transfer agents can be used to adjust the molecular weight of polymer (A). Examples of chain transfer agents include alkyl thiols (e.g., tert-dodecyl thiols, n-dodecyl thiols, etc.), carbon tetrachloride, thiodiglycol derivatives, diterpenes, terpinene derivatives, γ-terpinene derivatives, and α-methylstyrene dimers. One chain transfer agent can be used alone or in combination of two or more. The amount of chain transfer agent used is typically 0.05 parts by mass or more, preferably 0.1 to 15 parts by mass, relative to 100 parts by mass of the total monomers used in the polymerization.

[0069] It should be noted that during emulsion polymerization, chelating agents such as sodium ethylenediaminetetraacetate, glycine, and alanine; electrolytes such as potassium chloride, sodium phosphate, potassium phosphate, and potassium sulfate; activators such as sodium formaldehyde sulfoxylate and ferrous sulfate; pH adjusters such as ammonia, sodium hydroxide, and potassium hydroxide; and additives such as styrene-modified phenol, hindered phenol, imidazoles, p-phenylenediamine, and sodium dithionite, etc., can be added appropriately.

[0070] In the manufacture of polymer (A) based on emulsion polymerization, the polymerization can be continuous or batch. Furthermore, the emulsion polymerization used to obtain polymer (A) can be carried out through single-stage polymerization or multi-stage polymerization with two or more stages. The polymerization can be carried out in an oxygen-free reactor at a temperature typically 0–100°C, preferably 0–80°C. The polymerization time is preferably 1–36 hours, more preferably 4–24 hours. Additionally, operating conditions such as temperature or stirring can be appropriately changed during the reaction.

[0071] By keeping the total solids concentration in the emulsion polymerization at 50% by mass or less, the polymerization reaction can be carried out with good particle dispersion stability of the resulting polymer (A). The total solids concentration in the emulsion polymerization is preferably 48% by mass or less, more preferably 45% by mass or less.

[0072] Polymerization can be terminated by adding a polymerization terminator when the desired polymerization conversion is achieved. Examples of polymerization terminators include hydroxylamine compounds such as hydroxylamine and N,N-diethylhydroxylamine, and quinone compounds such as hydroquinone. After polymerization is terminated, unreacted monomers are removed from the reaction system by methods such as steam distillation, as needed, thereby obtaining a latex in which polymer (A) is dispersed in a dispersion medium.

[0073] After emulsion polymerization, the pH is preferably adjusted to approximately 4.5–10.5, more preferably 5–10, and even more preferably 5.5–9.5, by adding a neutralizing agent to the reaction product. Examples of neutralizing agents include metal hydroxides such as sodium hydroxide and potassium hydroxide, and ammonia. By setting the pH to the above range, the stability of polymer (A) becomes good. After neutralization, the reaction product is concentrated, thereby increasing the concentration of solid components while maintaining the good stability of polymer (A).

[0074] It should be noted that when recovering polymer (A) from an aqueous dispersion of polymer (A), it can be done, for example, by the following known method: precipitating the latex in warm water containing a coagulant and recovering the precipitate.

[0075] The content of polymer (A) in the conductive agent dispersion is preferably 50 to 800 parts by mass relative to 100 parts by mass of the total amount of carbon-based conductive agent contained in the conductive agent dispersion. By setting the content of polymer (A) relative to the carbon-based conductive agent within the above range, the dispersibility of the carbon-based conductive agent can be improved. From the viewpoint of improving the dispersibility of the carbon-based conductive agent, the content of polymer (A) relative to 100 parts by mass of the total amount of carbon-based conductive agent contained in the conductive agent dispersion is more preferably 80 parts by mass or more, and even more preferably 100 parts by mass or more. Furthermore, from the viewpoint of maintaining good dispersibility of the carbon-based conductive agent while maximizing the concentration of conductive agent in the conductive agent dispersion, the content of polymer (A) relative to 100 parts by mass of the total amount of carbon-based conductive agent contained in the conductive agent dispersion is more preferably 700 parts by mass or less, and even more preferably 650 parts by mass or less.

[0076] <Carbon-based conductive agents>

[0077] The carbon-based conductive agent (hereinafter referred to as "conductive agent (B)") contained in the conductive agent dispersion disclosed herein can be any material with carbon as the main component, and its type, shape, size, etc. are not particularly limited. Examples of conductive agents (B) include carbon nanotubes (CNT), carbon nanofibers (CNF), acetylene black, Ketjen black, furnace black, graphite (lead black), graphene, fullerene, carbon nanotubes, activated carbon, carbon fiber, etc.

[0078] Of these, the conductive agent (B) is preferably selected from at least one of carbon nanotubes, carbon nanofibers, furnace black, and acetylene black, more preferably from at least one of carbon nanotubes, carbon nanofibers, and acetylene black. Furthermore, from the viewpoint of achieving a greater improvement in the dispersibility of the polymer (A), it is further preferred to select one or both of carbon nanotubes and carbon nanofibers, particularly preferably carbon nanotubes. Since carbon nanotubes are elongated, they are prone to entanglement, and according to the polymer (A), even carbon-based conductive agents such as carbon nanotubes, which are prone to entanglement, can be dispersed at a uniform concentration in the liquid medium.

[0079] Examples of carbon nanotubes include single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multi-walled carbon nanotubes (MWCNTs). Furthermore, carbon nanotubes can be composed solely of carbon, or a portion of their structure can be replaced by other elements or chemically modified. Additionally, carbon nanotubes can be composites with metals (such as gold, silver, copper, aluminum, nickel, cobalt, titanium, platinum, etc.).

[0080] The size of the carbon nanotubes is not particularly limited. To ensure sufficient conductivity, the outer diameter of the carbon nanotubes is preferably 3–25 nm, more preferably 5–20 nm, and even more preferably 5–10 nm. In addition, the length of the carbon nanotubes is preferably 0.1–200 μm, more preferably 30–170 μm, and even more preferably 50–150 μm.

[0081] It should be noted that, in this specification, the outer diameter and length of carbon nanotubes can be calculated as follows: select any 300 carbon nanotubes from an image observed using a transmission electron microscope, measure the outer diameter of each carbon nanotube, and calculate its average value.

[0082] In the conductive agent dispersion, the content of conductive agent (B) relative to 100% by mass of the total solid content of the conductive agent dispersion is preferably 0.01 to 10% by mass, more preferably 0.02 to 7% by mass, and even more preferably 0.03 to 5% by mass. It should be noted that, in this specification, "total solid content" refers to the sum of the proportions of all components in the conductive agent dispersion, excluding the liquid medium.

[0083] <Liquid Medium>

[0084] The conductive agent dispersion disclosed herein contains a liquid medium. The liquid medium contained in the conductive agent dispersion of this disclosure (hereinafter also referred to as "liquid medium (C)") is preferably an organic solvent. Specifically, it is preferably at least one selected from aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ketones, esters, ethers, and lactams.

[0085] Specific examples include, as aliphatic hydrocarbons, hexane, heptane, octane, decane, and dodecane; as alicyclic hydrocarbons, cyclohexane, cycloheptane, cyclooctane, and cyclodecane; as aromatic hydrocarbons, toluene, xylene, mesitylene, naphthalene, and tetrahydronaphthalene; as ketones, methyl hexyl ketone and dipropyl ketone; as esters, butyl acetate, butyl butyrate, and methyl butyrate; as ethers, dibutyl ether, tetrahydrofuran, and anisole; and as lactams, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and 2-pyrrolidone. As a liquid medium (C), one type can be used alone, or two or more can be used in combination.

[0086] From the viewpoint of enabling better dispersibility of the conductive agent (B), the liquid medium (C) is preferably selected from one or more of ketones, esters, ethers and lactams, and more preferably from one or more of esters and lactams.

[0087] It should be noted that the conductive agent dispersion of this disclosure may contain water as a liquid medium (C). The proportion of water relative to the total amount of liquid medium (C) is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less.

[0088] The content of the liquid medium (C) is preferably such that the solid component concentration of the conductive agent dispersion is 0.1% to 20% by mass. By having the solid component concentration of the conductive agent dispersion within the above range, the concentration of the conductive agent (B) can be sufficiently increased while ensuring the dispersibility of the conductive agent (B). From the above viewpoint, the content of the liquid medium (C) is more preferably such that the solid component concentration of the conductive agent dispersion is 0.2% to 15% by mass, and even more preferably 0.5% to 10% by mass. It should be noted that, in this specification, the solid component concentration of the conductive agent dispersion refers to the percentage (by mass) of the total mass of the components included in the conductive agent dispersion, excluding the liquid medium (C), in the total mass of the conductive agent dispersion.

[0089] <Other Ingredients>

[0090] The conductive agent dispersion of this disclosure may contain components other than the polymer (A), carbon-based conductive agent, and liquid medium described above (hereinafter also referred to as "other components"). Examples of other components include polymers different from polymer (A) (e.g., methylcellulose, ethylcellulose, polyvinyl alcohol, polyvinyl butyral, etc.), preservatives, etc. The content of other components may be appropriately set without impairing the effects of this disclosure.

[0091] <Method for manufacturing conductive agent dispersion>

[0092] The conductive agent dispersion disclosed herein can be obtained by mixing the aforementioned polymer (A), a carbon-based conductive agent, a liquid medium, and any other components in combination. Specifically, the conductive agent dispersion can be prepared by mixing the solid polymer (A), the carbon-based conductive agent, and the liquid medium, or by mixing a polymer solution containing polymer (A) with the carbon-based conductive agent. It should be noted that when preparing the conductive agent dispersion, if a polymer solution containing polymer (A) is used, the conductive agent dispersion can be prepared by further adding a liquid medium to the polymer solution containing polymer (A).

[0093] There are no particular limitations on the method for obtaining the conductive agent dispersion. For example, the conductive agent dispersion can be obtained by mixing a mixture containing polymer (A), carbon-based conductive agent and liquid medium using a known dispersion apparatus.

[0094] Specific examples of dispersion devices include: dispersers, homogenizers, planetary mixers, and other mixers; homogenizers (e.g., Yoshida Machinery Kogyo Co., Ltd.'s "Nanovater", BRANSON Co., Ltd.'s Advanced Digital Sonifier (registered trademark) MODEL450DA, M-Technic Co., Ltd.'s "Clearmix", PRIMIX Co., Ltd.'s "Filmix", Silverson Co., Ltd.'s "Abramix", etc.); paint mixing machines (Red Devil Co., Ltd.); colloid mills (PUC Co., Ltd.'s "PUC Colloid Mill", IKA Co., Ltd.'s "Colloid Mill MK", etc.), conical mills (IKA Co., Ltd.'s "Conical Mill MKO", etc.); ball mills; sand mills (Shinmaru Enterprises Co., Ltd.'s "Dyno Mill", etc.); grinding mills; bead mills (Eirich Co., Ltd.'s "DCP Mill", etc.), co-ball mills, and other media dispersers; wet jet mills (Genus Co., Ltd.'s "Genus PY", Sugino Machine Co., Ltd.'s "Star"). Media-free dispersers such as "Burst", "Nanomizer" (manufactured by Nanozer Corporation), "Clear SS-5" (manufactured by M-Technic Corporation), and "MICROS" (manufactured by Nara Machinery Corporation); and other roller mills.

[0095] The conductive agent dispersion thus obtained can be applied to a variety of uses. Specifically, for example, the conductive agent dispersion of this disclosure can be used as a material for batteries, capacitors, wiring, wires, conductive films, semiconductor devices, various vehicles (automobiles, airplanes, trams, bicycles, etc.), building materials, sporting goods, medical equipment, audio equipment, optical equipment, antistatic materials, inks, coatings, etc. When using the conductive agent dispersion of this disclosure as a battery material, the type of battery is not particularly limited; examples include lithium-ion secondary batteries and fuel cells. Furthermore, when using the conductive agent dispersion of this disclosure as a capacitor material, examples include electric double-layer capacitors and lithium-ion capacitors. The conductive agent dispersion of this disclosure can be used as a conductive additive for these batteries or capacitors.

[0096] Based on the above description of this disclosure, the following solutions can be provided.

[0097] [Scheme 1] A conductive agent dispersion comprising a polymer (A), a carbon-based conductive agent (B), and a liquid medium (C), wherein the polymer (A) comprises repeating units (a1) from an aromatic vinyl compound and repeating units (a2) from an unsaturated carboxylic acid ester compound, wherein the proportion of repeating units (a1) is 1 to 50% by mass relative to the total number of repeating units contained in the polymer (A), and the proportion of repeating units (a2) is 20 to 75% by mass relative to the total number of repeating units contained in the polymer (A), wherein the polymer solution obtained by dissolving the polymer (A) in N-methyl-2-pyrrolidone at a solid component concentration of 8% by mass has a viscosity of 300 to 5000 mPa·s measured at 25°C.

[0098] [Scheme 2] According to the conductive agent dispersion of [Scheme 1], wherein the polymer (A) further comprises repeating units (a3) ​​from unsaturated carboxylic acids or unsaturated carboxylic anhydrides, and the proportion of the repeating units (a3) ​​is 0.5 to 10 by mass relative to the total amount of repeating units contained in the polymer (A).

[0099] [Scheme 3] According to the conductive agent dispersion of [Scheme 1] or [Scheme 2], wherein the polymer (A) further comprises repeating units (a4) from α,β-unsaturated nitrile compounds, and the proportion of the repeating units (a4) is 5 to 40 by mass relative to the total amount of repeating units contained in the polymer (A).

[0100] [Scheme 4] A conductive agent dispersion according to any one of [Scheme 1] to [Scheme 3], wherein the polymer (A) further comprises a repeating unit (a5) from a compound having a sulfonic acid group, and the proportion of the repeating unit (a5) is 0.1 to 10 by mass relative to the total amount of repeating units contained in the polymer (A).

[0101] [Scheme 5] A conductive agent dispersion according to any one of [Scheme 1] to [Scheme 4], wherein the polymer (A) further comprises a repeating unit (a6) from a (meth)acrylamide compound, and the proportion of the repeating unit (a6) is 0.1 to 10 by mass relative to the total amount of repeating units contained in the polymer (A).

[0102] [Scheme 6] A conductive agent dispersion according to any one of [Scheme 1] to [Scheme 5], wherein the carbon-based conductive agent (B) is selected from at least one of carbon nanotubes, carbon nanofibers, furnace black, acetylene black and graphene.

[0103] [Scheme 7] A conductive agent dispersion according to any one of [Scheme 1] to [Scheme 6], wherein the liquid medium (C) is selected from at least one of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ketones, esters, ethers and lactams.

[0104] Example

[0105] The present invention will now be specifically described based on embodiments, but the present invention is not limited to these embodiments. Unless otherwise specified, “parts” and “%” in the embodiments and comparative examples are based on mass.

[0106] [Example 1]

[0107] (1) Synthesis of polymer (A1)

[0108] Polymer (A1) was obtained through a single-stage polymerization process as shown below. In a 3L detachable flask, 500 parts by weight of water, 0.8 parts by weight of 4,4'-azobis(4-cyanopentanoic acid), 0.64 parts by weight of sodium bicarbonate, 1 part by weight of styrene, 67 parts by weight of 2-ethylhexyl acrylate, 1 part by weight of acrylic acid, 30 parts by weight of acrylonitrile, and 1 part by weight of sodium styrene sulfonate were added. After bubbling under nitrogen for 30 minutes, the reaction was carried out at 70°C for 5 hours. The mixture was then cooled to obtain an aqueous solution containing 15% polymer (A1) based on solids concentration. The conversion rate of polymer (A1) at this point was 99%.

[0109] Next, 1 part by weight of 2,6-di-tert-butyl-p-cresol was added as an anti-aging agent. The aqueous dispersion of the polymer (A1) with the added anti-aging agent was added dropwise to 3000 parts by weight of a 0.5% calcium chloride aqueous solution. The resulting coagulant was washed with water, and a portion of the coagulant was dried at 80°C and all of it was recovered.

[0110] The details of the method for determining polymerization conversion are as follows.

[0111] <Methods for Determining Polymerization Conversion Rate>

[0112] The polymerized reaction solution was extracted at a specified time and placed into an aluminum dish (X (g)) whose mass had been pre-measured. The mass of the reaction solution (Y (g)) was measured. The aluminum dish containing the reaction solution was dried at 155°C for 15 minutes using a hot air dryer. After removing the aluminum dish and allowing it to cool, the mass of the aluminum dish (Z (g)) was measured. Based on the measured values ​​of X, Y, and Z, the polymerization conversion rate (%) was calculated using the following mathematical formula (1).

[0113] Polymerization conversion rate (%) = ((Z-X) / Y) × 100 ……(1)

[0114] (2) Evaluation of polymers

[0115] The polymer (A1) obtained by synthesis example 1 was evaluated as follows.

[0116] (i) Evaluation of NMP solubility

[0117] The polymer (A1) was diluted with N-methyl-2-pyrrolidone (NMP) to a concentration of 1% by mass. The transparency of the polymer solution at 1 atmosphere and 23°C was visually assessed. A clear solution indicated that the polymer was dissolved in NMP, while a translucent or cloudy solution indicated that the polymer was insoluble in NMP. The results showed that polymer (A1) was dissolved in NMP. It should be noted that in Tables 1 and 2 described later, the case of polymer dissolution in NMP is denoted as "A", and the case of polymer insolubility in NMP is denoted as "B".

[0118] (ii) Determination of viscosity of 8% NMP

[0119] Polymer (A1) was added to N-methyl-2-pyrrolidone (NMP) and stirred overnight to dissolve polymer (A1) in NMP, resulting in a polymer solution with a polymer (A1) content of 8% by mass. The viscosity of this polymer solution (8% NMP viscosity) was measured at 25°C using a Type B viscometer (Toki Sangyo Co., Ltd., "TVB-10"), and the result was 820 mPa·s.

[0120] (3) Preparation and evaluation of conductive agent dispersion

[0121] (i) Preparation of conductive agent dispersion

[0122] 1000 parts by mass of NMP as a liquid medium were added to a container containing 4 parts by mass of single-walled carbon nanotubes (SWCNT, manufactured by OCSiAl, "TUBALL") and 20 parts by mass of polymer (Al). The resulting mixture was then ultrasonically dispersed for 10 minutes, and subsequently passed through a high-pressure homogenizer (manufactured by Yoshida Machinery Co., Ltd., product name "Nanovater") 5 times at 100 MPa to prepare a conductive agent dispersion.

[0123] (ii) Evaluation of CNT dispersion

[0124] The conductive agent dispersion obtained above was diluted with NMP to a viscosity of 1000–20000 mPa·s, measured using a Type B viscometer (Toki Sangyo Co., Ltd., “TVB-10”) at 25°C. The viscosity measured at this point was taken as the “initial slurry viscosity”.

[0125] Next, at 25°C, an Anton Paar rheometer (MCR-500 model) was used with a 25mm diameter, 2-degree angle cone plate as the measuring instrument to evaluate the shear rate-shear viscosity under reciprocating conditions of 1 (1 / s) to 1000 (1 / s). The shear viscosity at 5 (1 / s) for both the forward and return strokes was read, and the rate of change of shear viscosity (%) was calculated. The measurement results are shown in Table 1.

[0126] It should be noted that if the rate of change of shear viscosity is less than 50%, the tested sample can be judged as a conductive agent dispersion with low hysteresis, low structural viscosity, and good operability. On the other hand, if the rate of change of shear viscosity is greater than 50%, the tested sample can be judged as a conductive agent dispersion with high hysteresis, high structural viscosity, and therefore poor operability.

[0127] [Examples 2-16, Comparative Examples 1-6]

[0128] The types and amounts of monomers are shown in Tables 1 and 2, respectively. Except as in Example 1, each polymer (polymers (A2) to (A16), polymers (R1) to (R6)) was synthesized via single-stage polymerization and evaluated. Furthermore, conductive agent dispersions were prepared using each synthesized polymer in the same manner as in Example 1 and evaluated. The monomer composition, property test results, and evaluation results of the polymers synthesized and used in Examples 1-16 and Comparative Examples 1-6 are shown in Tables 1 and 2. It should be noted that the values ​​representing the monomer composition of the polymers shown in Tables 1 and 2 represent the amount of each monomer relative to 100 parts by mass of the total monomers used in the synthesis of each polymer (unit: parts by mass). The values ​​representing the amount of conductive agent dispersion represent the amount of each component relative to 100 parts by mass of the liquid medium used in the preparation of the conductive agent dispersion (unit: parts by mass) (the same applies to Table 3).

[0129] [Table 1]

[0130]

[0131] [Table 2]

[0132]

[0133] In Tables 1 and 2, the abbreviations of the monomers represent the following compounds.

[0134] <Single>

[0135] (Aromatic vinyl compounds)

[0136] ST: Styrene

[0137] VT: Vinyltoluene

[0138] ·4tBST: 4-tert-butylstyrene

[0139] (Unsaturated carboxylic acid ester compounds)

[0140] MMA: Methyl methacrylate

[0141] ·TADB: Dibutyl itaconic acid

[0142] ·TADM: Dimethyl itaconic acid

[0143] ·TADE: Diethyl itaconic acid

[0144] ·BA: Butyl acrylate

[0145] ·2EHA: 2-Ethylhexyl acrylate

[0146] HEMA: Hydroxyethyl methacrylate

[0147] CHMA: Cyclohexyl methacrylate

[0148] (Unsaturated carboxylic acids)

[0149] ·TA: Itaconic acid

[0150] ·TAMB: Monobutyl itaconic acid

[0151] ·TAMM: Monomethyl itaconic acid

[0152] • TAME: Monoethyl itaconic acid

[0153] AA: Acrylic acid

[0154] MAA: Methacrylic acid

[0155] (α,β-unsaturated nitrile compounds)

[0156] AN: Acrylonitrile

[0157] DMP: Isopropylidene malononitrile

[0158] FN: Fumarium

[0159] TCE: Tetracyanoethylene

[0160] (Sulfonic acid or its salt)

[0161] •NaSS: Sodium styrene sulfonate

[0162] ·VS: Vinylsulfonic acid

[0163] (Methacrylamide)

[0164] AAM: Acrylamide

[0165] MAM: Methacrylamide

[0166] [Examples 17-23, Comparative Examples 7 and 8]

[0167] The type and amount of carbon-based conductive agent were changed as described in Table 3. Otherwise, the conductive agent dispersion was prepared in the same manner as in Example 1 and evaluated. The evaluation results are shown in Table 3.

[0168] [Table 3]

[0169]

[0170] In Table 3, the abbreviations for carbon-based conductive agents represent the following compounds.

[0171] <Carbon-based conductive agents>

[0172] •B-1: "TUBALL" manufactured by OCSiAl.

[0173] •B-2: KUMHO PETROCHEMICAL "100T"

[0174] • B-3: "Flotube7010" manufactured by Cnano Corporation

[0175] • B-4: Resonac Corporation "VGCF-H"

[0176] • B-5: Electric Chemical Company's "HS-100"

[0177] • B-6: IMERYS "Super CT"

[0178] As shown in Tables 1 to 3, by including polymer (A) as a dispersant together with carbon-based conductive agents in a liquid medium, a conductive agent dispersion with excellent dispersibility of carbon-based conductive agents can be obtained.

Claims

1. A conductive agent dispersion comprising polymer A, carbon-based conductive agent B, and liquid medium C, The polymer A comprises repeating unit a1 from an aromatic vinyl compound and repeating unit a2 from an unsaturated carboxylic acid ester compound. The proportion of the repeating unit a1 relative to the total number of repeating units contained in the polymer A is 1-50% by mass. The proportion of repeating unit a2 relative to the total number of repeating units contained in polymer A is 20-75% by mass. The viscosity of a polymer solution prepared by dissolving polymer A in N-methyl-2-pyrrolidone at a solid content of 8% by mass was measured at 25°C to be 300–5000 mPa·s.

2. The conductive agent dispersion according to claim 1, wherein, The polymer A further comprises repeating unit a3 derived from unsaturated carboxylic acids or unsaturated carboxylic anhydrides. The proportion of the repeating unit a3 is 0.5 to 10 by mass relative to the total number of repeating units contained in the polymer A.

3. The conductive agent dispersion according to claim 1, wherein, The polymer A further comprises repeating unit a4 from an α,β-unsaturated nitrile compound. The proportion of the repeating unit a4 is 5 to 40 by mass relative to the total number of repeating units contained in the polymer A.

4. The conductive agent dispersion according to any one of claims 1 to 3, wherein, The polymer A further comprises repeating unit a5 from a compound having a sulfonic acid group. The proportion of the repeating unit a5 is 0.1 to 10 by mass relative to the total number of repeating units contained in the polymer A.

5. The conductive agent dispersion according to any one of claims 1 to 3, wherein, The polymer A further comprises a repeating unit a6 from a (meth)acrylamide compound. The proportion of the repeating unit a6 is 0.1 to 10 by mass relative to the total number of repeating units contained in the polymer A.

6. The conductive agent dispersion according to any one of claims 1 to 3, wherein, The carbon-based conductive agent B is selected from at least one of carbon nanotubes, carbon nanofibers, furnace black, acetylene black, and graphene.

7. The conductive agent dispersion according to any one of claims 1 to 3, wherein, The liquid medium C is selected from at least one of aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, ketones, esters, ethers, and lactams.

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