Carbon material dispersion liquid and application thereof

Abstract

The invention relates to a carbon material dispersion liquid and an application thereof. A carbon material dispersion containing a carbon material containing carbon nanotubes, a liquid medium, and a dispersant, the carbon material dispersion being characterized in that the carbon material dispersion does not contain a volatile salt, the content of the dispersant in terms of solid content is 204 parts by mass or less per 100 parts by mass of the carbon material, and when the liquid medium is an organic solvent, the content of the dispersant in terms of solid content is 2,000 parts by mass or less. The dispersing agent is a dispersing agent c or a dispersing agent f, the trade name of the dispersing agent c is' DYSPERBYK-9077 ', and the trade name of the dispersing agent f is' TEGO Dispers 670 '; and when the liquid medium is an aqueous medium, the carbon material dispersion liquid also contains a defoaming agent.

Description

[0001] This application is a divisional application of the application with the filing date of August 4, 2022, application number 202280066879.2, and invention title "Carbon material dispersion liquid and its applications". Technical Field

[0002] The present invention relates to a carbon material dispersion liquid and an article using the same. Background Art

[0003] Carbon materials (nanocarbon materials) such as carbon black, carbon fiber, carbon nanotube, graphite, and graphene have a six-membered ring graphite structure formed by covalent bonds of carbon atoms, and are materials that exhibit various properties such as electrical conductivity and heat conductivity. Methods for making their properties play a role in various fields are being studied. For example, paying attention to the electrical properties, thermal properties, and properties as fillers of carbon materials, applications to antistatic agents, conductive materials, plastic reinforcing materials, semiconductors, fuel cell electrodes, and cathode wires of transducers are being studied.

[0004] In these applications, a carbon material dispersion liquid in which the carbon material has good dispersibility and maintains the dispersibility for a long time is necessary. However, the surface energy of nanosized carbon materials is high, and they exhibit strong van der Waals forces, so they tend to aggregate. Therefore, even when dispersed in a liquid medium, they often aggregate directly. Therefore, various studies have been conducted to stably disperse carbon nanotubes in a liquid medium.

[0005] To stably disperse carbon materials in a liquid medium, general dispersants are used. For example, in Patent Documents 1 and 2, a solvent-based dispersion liquid of carbon nanotubes using a cationic surfactant such as an alkanolamine salt or a polymer dispersant such as a styrene-acrylic resin is proposed. It should be noted that in Patent Documents 3 and 4, a dispersion liquid for judging the dispersion state by measuring the average particle size distribution is proposed. In addition, in Patent Documents 5 and 6, a dispersion liquid for judging the dispersion state by measuring viscosity is proposed. Furthermore, in Patent Document 7, the dispersibility of carbon nanotubes is evaluated based on the product of dynamic viscoelasticity and phase angle. In Patent Documents 8 and 9, the dispersion state of a graphene dispersion liquid is determined based on the absorbance ratio. In Patent Documents 10 and 11, carbon nanotubes are dispersed using carboxymethyl cellulose or its salt.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-174084

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-537570

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2007-076998

[0011] Patent Document 4: Japanese Patent Application Laid-Open No. 2020-019924

[0012] Patent Document 5: Japanese Patent Application Laid-Open No. 2010-254546

[0013] Patent Document 6: Japanese Patent Application Laid-Open No. 2015-003859

[0014] Patent Document 7: Japanese Patent No. 6860740

[0015] Patent Document 8: Japanese Patent No. 6152924

[0016] Patent Document 9: Japanese Patent No. 6696632

[0017] Patent Document 10: Japanese Patent Application Laid-Open No. 2016-028109

[0018] Patent Document 11: Japanese Patent Application Laid-Open No. 2016-204203 Summary of the Invention

[0019] Problems to be Solved by the Invention

[0020] In order to grasp the dispersion state of a carbon material containing carbon nanotubes in a liquid medium and judge the quality of characteristics such as the viscosity stability of a carbon material dispersion liquid, for example, there are methods such as measuring the dispersion particle diameter and particle size distribution of the carbon material in the carbon material dispersion liquid. However, it is originally difficult to grasp the dispersion state of the carbon material only by the median particle diameter of the particle size distribution. Furthermore, carbon nanotubes are fibrous substances with a very large aspect ratio, so it is difficult to distinguish between the fiber diameter and the fiber length for measurement, and it is even more difficult to accurately grasp the dispersion state. It should be noted that when carbon nanotubes are dispersed in a liquid medium by a general dispersion treatment method, it is difficult to determine from the median particle diameter of the particle size distribution whether the aggregates of carbon nanotubes are loosened and the dispersion particle diameter becomes smaller, or whether the carbon nanotubes themselves are cut and the dispersion particle diameter becomes smaller.

[0021] In addition, as a method for determining the quality of properties such as the viscosity stability of a carbon material dispersion, there is also a method of measuring the viscosity of the carbon material dispersion to make a judgment. However, depending on the type and concentration of the carbon material represented by carbon nanotubes, the viscosity of the obtained dispersion is likely to vary. Furthermore, in the case of carbon nanotubes, if the aggregation is loosened, the viscosity of the dispersion increases, and as the dispersion progresses, the viscosity of the dispersion decreases. If the dispersion progresses further, the broken carbon nanotubes aggregate again, and thus, the viscosity of the dispersion increases. Therefore, it is difficult to judge the quality of the dispersion state of the carbon material only by measuring the viscosity of the dispersion. Furthermore, it is impossible to immediately judge the viscosity stability of the prepared dispersion, and tests need to be carried out after long-term storage.

[0022] For example, Patent Document 7 proposes to evaluate the dispersibility of carbon nanotubes based on the product of dynamic viscoelasticity and phase angle. However, for either dynamic viscoelasticity or phase angle, depending on the type of carbon nanotubes to be used, there is a possibility of obtaining a value different from the expected value. Therefore, it is substantially difficult to evaluate the dispersibility of carbon nanotubes.

[0023] In addition, Patent Documents 8 and 9 propose to determine the dispersion state of a graphene dispersion based on the absorbance ratio. However, for carbon materials other than graphene (such as carbon nanotubes), the wavelengths used to calculate the absorbance ratio are different, and the appropriate concentrations and absorbance ratios are also different. Therefore, it is difficult to accurately evaluate the dispersion state of carbon materials other than graphene.

[0024] The present invention has been made in view of the problems of such prior art, and its object is to provide a carbon material dispersion having excellent viscosity stability, which is well dispersed without substantially generating coarse aggregates regardless of the liquid composition and dispersion method and including carbon nanotubes. Another object of the present invention is to provide various products obtained using the carbon material dispersion.

[0025] Means for Solving the Problems

[0026] That is, according to the present invention, there is provided a carbon material dispersion as shown below.

[0027] [1] A carbon material dispersion containing: a carbon material including carbon nanotubes, a liquid medium, and a dispersant, with the absorbance of a diluted dispersion obtained by diluting with a dilution liquid containing the liquid medium being 1.2 to 2.2 in such a manner that the absorbance at any wavelength W within the range of 350 to 550 nm L and any wavelength W within the range of 650 to 850 nm H at the central value wavelength W M of the absorbance at the wavelength W of the diluted dispersion L at the wavelength W L with respect to the wavelength W HAbsorbance A H The ratio (A L / A H ) is 1.40 or more.

[0028] [2] The carbon material dispersion according to [1] above, wherein the diluent is a blank liquid having the same composition as the carbon material dispersion except that it does not contain the carbon material.

[0029] [3] The carbon material dispersion according to [1] or [2] above, wherein the wavelength W L is 380 nm, the wavelength W H is 780 nm, and the wavelength W M is 580 nm, the absorbance at the wavelength W M is 1.5 to 2.0, and the ratio of the absorbance A L to the absorbance A H (A 380 / A 780 ) is 1.60 or more.

[0030] [4] The carbon material dispersion according to any one of [1] to [3] above, wherein the liquid medium is an aqueous medium, the dispersant is a cellulose derivative or a polymer dispersant, the viscosity of a 1 mass% aqueous solution of the cellulose derivative is 20 to 500 mPa·s, and the degree of etherification is 0.5 to 0.9. The polymer dispersant is a polymer comprising: structural unit (1) of at least one monomer 1 selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, and their quaternary ammonium salts in an amount of 5 to 40 mass%; structural unit (2) of monomer 2 represented by the following general formula (1) in an amount of 50 to 80 mass%; and structural unit (3) of monomer 3 copolymerizable with the monomer 1 and the monomer 2 in an amount of 0.5 to 40 mass%. The monomer 3 includes α-methylstyrene and (meth)acrylic acid. The content of the structural unit derived from the α-methylstyrene is 0.5 to 5 mass%, and the content of the structural unit derived from the (meth)acrylic acid is 0.5 to 30 mass%. And the number average molecular weight of the polymer is 5000 to 20000.

[0031]

[0032] (In the general formula (1), R 1 represents a hydrogen atom or a methyl group, A represents O or NH, X represents an ethylene group or a propylene group, Y represents O, NHCOO, or NHCONH, R 2 independently represent a hydrogen atom or a methyl group, n represents an average number of repeating units of 20 to 100, and R 3 represents a hydrogen atom or a methyl group. Among them, R2 The number of repeating units n of hydrogen atoms H The total number of repeating units n T more than 1 / 2 of)

[0033] [5] The carbon material dispersion according to [4] above, wherein the cellulose derivative is carboxymethyl cellulose or sodium carboxymethyl cellulose.

[0034] [6] The carbon material dispersion according to any one of [1] to [3] above, wherein the liquid medium is an organic solvent, and the dispersant is a polymer comprising: structural units (A) derived from monomer A represented by the following general formula (A) in an amount of 3 to 55% by mass; structural units (B) derived from monomer B represented by the following general formula (B) in an amount of 30% by mass or less; structural units (C) derived from monomer C represented by the following general formula (C) in an amount of 45 to 90% by mass; and structural units (D) derived from monomer D copolymerizable with these monomers in an amount of 0.5 to 20% by mass, and the amine value of the polymer is 100 mgKOH / g or less and the number average molecular weight is 5000 to 20000.

[0035]

[0036] (In the above general formula (A), R represents a hydrogen atom or a methyl group, A represents O or NH, B represents an ethylene group or a propylene group, R 1 and R 2 independently represent a methyl group or an ethyl group, Ar represents a phenyl group, a naphthyl group, an anthracenyl group, or a pyrenyl group, and X represents a chlorine atom, a bromine atom, bis(trifluoromethyl)sulfonimide, or bis(nonafluorobutanesulfonyl)imide)

[0037]

[0038] (In the above general formula (B), R represents a hydrogen atom or a methyl group, A represents O or NH, B represents an ethylene group or a propylene group, R 1 and R 2 independently represent a methyl group or an ethyl group)

[0039]

[0040] (In the above general formula (C), R represents a hydrogen atom or a methyl group, A represents O or NH, Q represents an ethylene group or a methylethylene group, Y represents O, NHCOO, or NHCONH, m and n independently represent the average number of repeating units of 0 or more and m + n = 20 to 100, and R 3 represents an alkyl group, an aryl group, or an alkylaryl group having 1 to 18 carbon atoms)

[0041] [7] The carbon material dispersion according to any one of the foregoing [1] to [6], wherein, relative to 100 parts by mass of the foregoing carbon material, the content of the foregoing dispersant is 10 to 500 parts by mass, the content of the foregoing carbon material is 10% by mass or less, and the content of the foregoing dispersant is 30% by mass or less.

[0042] In addition, according to the present invention, the following products are provided.

[0043] [8] Any product of a coating, ink, coating agent, resin molding material, conductive material, heat conductive material, and antistatic material, which contains the carbon material dispersion according to any one of the foregoing [1] to [7].

[0044] [9] Any product of a battery material and a mechanical component, which has a coating film formed from the carbon material dispersion according to any one of the foregoing [1] to [7].

[0045] Effects of the Invention

[0046] According to the present invention, it is possible to provide a carbon material dispersion having excellent viscosity stability in which carbon materials including carbon nanotubes are well dispersed without substantially generating coarse aggregates regardless of the liquid composition and dispersion method. In addition, according to the present invention, various products obtained using this carbon material dispersion can be provided.

[0047] By selecting the type of carbon nanotubes used in the carbon material dispersion, etc., it is expected to form a coating film with high transparency, for example. In addition, since the carbon material containing carbon nanotubes in a sufficiently loosened state is dispersed, it is expected to greatly exhibit the characteristics of carbon nanotubes themselves such as conductivity, heat conductivity, and antistatic properties. Detailed Embodiments

[0048] <Carbon Material Dispersion>

[0049] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. The carbon material dispersion of the present invention contains: a carbon material containing carbon nanotubes, a liquid medium, and a dispersant. Moreover, in a dilute dispersion obtained by diluting with a diluent containing a liquid medium so that the absorbance at a wavelength W belonging to any wavelength range of 350 to 550 nm L and any wavelength W belonging to the range of 650 to 850 nm H at the median value ((W L +W H ) / 2) of the wavelength W M becomes 1.2 to 2.2, the absorbance A L at the wavelength W L of the dilute dispersion H relative to the absorbance A H at the wavelength WL / A H ) is 1.40 or more. Hereinafter, the carbon material dispersion liquid will also be simply referred to as "dispersion liquid".

[0050] (Carbon material)

[0051] The carbon material includes carbon nanotubes. As the carbon nanotubes, multi-walled carbon nanotubes with multiple layers and single-walled carbon nanotubes with a single layer can be used. There are no particular limitations on the diameter, length, shape, manufacturing method, etc., and any carbon nanotubes can be used. The carbon nanotubes may be doped with metals such as platinum and palladium, and metal salts. In addition, the carbon nanotubes can be surface-modified by oxidation treatment, plasma treatment, radiation treatment, corona treatment, and coupling treatment, etc.

[0052] As carbon materials other than carbon nanotubes, carbon black, carbon fiber, graphite, and graphene, etc. can be used. As the carbon black, acetylene black, furnace black, thermal cracking carbon black, Ketjen black, etc. can be cited. There are no particular limitations on physical property values such as the structure, oil absorption amount, and specific surface area of the carbon black, and the presence or absence of surface modification such as oxidation, and conventionally known carbon black can be used.

[0053] As the carbon fiber, PAN-based carbon fiber using polyacrylonitrile as a raw material, pitch-based carbon fiber using pitch-based materials as a raw material, and their recycled products, etc. can be cited. Among them, carbon nanofibers with a fiber diameter in the nanometer size and a shape in which a six-membered ring graphite structure is rolled into a tube shape are preferred. There are no particular limitations on the particle size, fiber diameter, fiber length, shape, and manufacturing method, etc. of the carbon materials other than carbon nanotubes. The carbon materials may be doped with metals such as platinum and palladium, and metal salts. The carbon materials can be surface-modified by performing oxidation treatment, plasma treatment, radiation treatment, corona treatment, and coupling treatment, etc.

[0054] (Liquid medium)

[0055] As the liquid medium, an aqueous medium and an organic solvent can be used. When the liquid medium is an aqueous medium, the carbon material dispersion liquid is an aqueous dispersion liquid. In addition, when the liquid medium is an organic solvent, the carbon material dispersion liquid is a solvent-based (oil-based) dispersion liquid.

[0056] As the aqueous medium, water or a mixed solvent of water and a water-soluble organic solvent can be used. An aqueous dispersion using an aqueous medium as the liquid medium is a more environmentally friendly dispersion. Examples of the water-soluble organic solvent include alcohols such as methanol, ethanol, and isopropyl alcohol; polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and glycerol; ethers such as tetrahydrofuran; glycol ethers such as diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether; glycol ether esters such as diethylene glycol monomethyl ether acetate; amides such as pyrrolidone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; urea-based solvents such as tetramethylurea and dimethyl-1,3-imidazolidinone; sulfur-containing solvents such as dimethyl sulfoxide and sulfolane; ionic liquids such as 1-ethyl-3-methylimidazolium chloride; and the like. The content of the water-soluble organic solvent in the dispersion is preferably set to 20% by mass or less, and more preferably 10% by mass or less. If the content of the water-soluble organic solvent in the dispersion exceeds 20% by mass, the function of the dispersant may sometimes be easily reduced.

[0057] As the water-soluble organic solvent, isopropyl alcohol (IPA) and ethanol are preferably used. When these water-soluble organic solvents are used and the dispersion is used as ink or a coating material, the wettability to the substrate and the drying property of the coating film can be improved.

[0058] When the carbon material dispersion is a solvent-based (oil-based) dispersion, as the organic solvent, conventionally known organic solvents can be used. It should be noted that water can be used together with the organic solvent. Examples of the organic solvent include: hydrocarbon solvents such as hexane, toluene, and xylene; alcohol solvents such as methanol, ethanol, isopropanol, butanol, and dodecanol; ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, and isobutyl methyl ketone; ester solvents such as ethyl acetate, butyl acetate, amyl acetate, dimethyl succinate, dimethyl adipate, methyl lactate, and dimethyl lactate; ether solvents such as dipropyl ether, tetrahydrofuran, and dioxane; carbonate solvents such as dimethyl carbonate, ethylene carbonate, and propylene carbonate; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, pyrrolidone, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; urea solvents such as tetramethylurea and dimethylimidazolidinone; sulfoxide solvents such as dimethyl sulfoxide; glycol monoether solvents such as ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether; glycol diether solvents such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and dipropylene glycol dimethyl ether; glycol ether monoether ester solvents such as ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monobutyl ether acetate; etc.

[0059] In addition, reactive monomers such as (meth)acrylic monomers, vinyl ether monomers, epoxy compounds, and oxetane compounds can be used as the organic solvent. By using such reactive monomers as the organic solvent, a carbon material dispersion capable of preparing an ultraviolet ray / electron beam curable ink, an ultraviolet ray / electron beam curable coating agent, etc. can be formed.

[0060] (Dispersant)

[0061] The dispersant is a component for dispersing the carbon material in the liquid medium. As the dispersant, anionic, cationic, nonionic, and amphoteric surfactants; polymer dispersants can be used. Among them, it is preferable to use a polymer (resin) as the dispersant. When the liquid medium is an aqueous medium containing water, the dispersant is preferably a cellulose derivative or a polymer dispersant.

[0062] When the liquid medium is an aqueous medium containing water and the cellulose derivative is used as a dispersant, examples thereof include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and metal salts thereof. Among them, carboxymethyl cellulose and sodium carboxymethyl cellulose are preferred. Further, the cellulose derivative preferably has a viscosity of 20 to 500 mPa·s in a 1% by mass aqueous solution and an etherification degree of 0.5 to 0.9. By using such a cellulose derivative, the carbon nanotubes can be more favorably dispersed and the storage stability can be improved.

[0063] When the liquid medium is an aqueous medium containing water, the polymer dispersant used as a dispersant is preferably a polymer comprising 5 to 40% by mass of a structural unit (1) derived from at least one monomer 1 selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, and quaternary ammonium salts thereof; 50 to 80% by mass of a structural unit (2) derived from monomer 2 represented by the following general formula (1); and 0.5 to 40% by mass of a structural unit (3) derived from monomer 3 copolymerizable with monomer 1 and monomer 2, and the number average molecular weight of the polymer is 5000 to 20000.

[0064]

[0065] (In the above general formula (1), R 1 represents a hydrogen atom or a methyl group, A represents O or NH, X represents an ethylene group or a propylene group, Y represents O, NHCOO, or NHCONH, R 2 independently of each other represents a hydrogen atom or a methyl group, n represents an average repeating unit number of 20 to 100, R 3 represents a hydrogen atom or a methyl group. Among them, the repeating unit number n 2 wherein R H is a hydrogen atom is 1 / 2 or more of the total repeating unit number n T )

[0066] As typical basic monomers, there are also dimethylaminoethyl (meth)acrylate and the like. However, by using any one of 2-vinylpyridine, 4-vinylpyridine, and 1-vinylimidazole, the dispersion stability of the carbon material dispersion can be further improved, and the viscosity of the carbon material dispersion can be reduced. 2-Vinylpyridine, 4-vinylpyridine, and 1-vinylimidazole are all monomers having an aromatic ring, and this aromatic ring has a structure similar to the 6-membered ring structure of the carbon material. Therefore, it is considered that by adopting the structural unit (1) derived from these monomers, the adsorption force to the carbon material based on van der Waals force and π-π stacking can be increased. Furthermore, there is a case where the surface of the carbon material is oxidized and carboxyl groups and phenolic hydroxyl groups are present. It is considered that by ionically bonding the carboxyl groups and phenolic hydroxyl groups to the basic groups in the structural unit (1), the polymer dispersant becomes more easily adsorbed to the carbon material, and the dispersibility is further improved. It should be noted that monomer 1 is particularly preferably 4-vinylpyridine.

[0067] As monomer 1, by using the quaternary ammonium salts of 2-vinylpyridine, 4-vinylpyridine, and 1-vinylimidazole, the dispersibility can be further improved. By quaternizing the structural units derived from 2-vinylpyridine, 4-vinylpyridine, and 1-vinylimidazole, the structural unit (1) derived from the quaternary ammonium salt can be prepared. As the material for quaternization (quaternizing agent), for example, halides and sulfates can be used. As the halides, chloromethane, benzyl chloride, etc. can be cited. As the sulfates, dimethyl sulfate, diethyl sulfate, etc. can be cited. As the quaternary ammonium salt, arylmethyl halide is preferred. As the arylmethyl, benzyl, naphthylmethyl, anthracenylmethyl, pyrenylmethyl, etc. can be cited. Among them, naphthylmethyl is preferred.

[0068] Monomer 2 is a macromonomer having a polyalkylene glycol chain represented by the following general formula (1). By introducing the structural unit (2) derived from monomer 2, a polymer having a structure in which a polyalkylene glycol chain is grafted can be prepared. The polyalkylene glycol chain is soluble in water as a liquid dispersion medium. Then, the structural unit (1) adsorbed on the carbon material is repelled due to the steric hindrance between particles caused by the dissolution of the polyalkylene glycol chain, so that the carbon material can be stably dispersed in the liquid dispersion medium in a good state for a long time.

[0069]

[0070] (In the foregoing general formula (1), R 1 represents a hydrogen atom or a methyl group, A represents O or NH, X represents an ethylene group or a propylene group, Y represents O, NHCOO, or NHCONH, R 2 independently represent a hydrogen atom or a methyl group, n represents an average repeating unit number of 20 to 100, and R 3 represents a hydrogen atom or a methyl group. Among them, R2 The number of repeating units n of hydrogen atoms H is the total number of repeating units n T more than 1 / 2 of)

[0071] The molecular weight of monomer 2 represented by the general formula (1) is about 880 to 5800. In the general formula (1), R 2 is the number of repeating units n of hydrogen atoms H is the total number of repeating units n T is more than 1 / 2 of this, whereby the polyalkylene glycol chain can be made water-soluble. Among them, R 2 is the number of repeating units n of hydrogen atoms H is preferably more than 3 / 5 of the total number of repeating units n T of.

[0072] Monomer 3 is a monomer that can copolymerize with monomer 1 and monomer 2. As monomer 3, a (meth)acrylic acid-based monomer is preferably used. Specific examples of monomer 3 include (meth)acrylic acid; monofunctional (meth)acrylates having substituents such as methyl, ethyl, propyl, butyl, pentyl, 2-ethylhexyl, isooctyl, nonyl, dodecyl, hexadecyl, octadecyl, isostearyl, behenyl, cyclohexyl, trimethylcyclohexyl, tert-butylcyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, nonylphenoxyethyl, glycidyl, isobornyl, dicyclopentyl, dicyclopentenyl, dicyclopentyloxyethyl, 2-hydroxyethyl, 2-hydroxypropyl, 4-hydroxybutyl, etc.; poly(n = 2 or more) alkylene (carbon number 2 to 4) glycol mono(meth)acrylates, poly(n = 2 or more) alkylene (carbon number 2 to 4) glycol monoalkyl (carbon number 1 to 22) mono(meth)acrylates, poly(n = 2 or more) hydroxyalkanoic acid (carbon number 5 to 18) mono(meth)acrylates, etc. as polymer-type (meth)acrylates of macromonomers. In addition, vinyl monomers such as styrene, vinyltoluene, vinylnaphthalene, vinylcaprolactone, α-methylstyrene, and vinyl acetate can also be used as monomer 3.

[0073] By using α-methylstyrene as monomer 3, the molecular weight can be easily controlled, so it is preferred. Specifically, monomer 3 contains α-methylstyrene, and in the polymer, the content of the structural unit derived from α-methylstyrene is preferably 0.5 to 5% by mass, more preferably 1 to 3% by mass. When the content of the structural unit derived from α-methylstyrene is less than 0.5% by mass, polymerization may sometimes proceed slightly unevenly, and there may be a case where monomer 2 remains or gelation occurs. On the other hand, when the content of the structural unit derived from α-methylstyrene is greater than 5% by mass, there may be a case where α-methylstyrene with slightly poor polymerizability remains, or the molecular weight is overly controlled and the polymerization rate is slightly reduced.

[0074] In addition, as the monomer 3, (meth)acrylic acid is preferably used. By including a structural unit derived from (meth)acrylic acid as an acid component, the water solubility of the polymer is improved. When a quaternary ammonium group is also present in the polymer, the polymer exhibits amphoteric ionicity, so it can be easily adsorbed ionically on the carbon material and the dispersibility can be further improved. In addition, by exhibiting amphoteric ionicity, the polymer forms ionic bonds intramolecularly / intermolecularly and easily forms a crosslinked structure, which can further suppress detachment from the carbon material.

[0075] In the polymer, the content of the structural unit derived from (meth)acrylic acid is preferably 0.5 to 30% by mass, more preferably 1 to 10% by mass. When the content of the structural unit derived from (meth)acrylic acid is less than 0.5% by mass, there is a tendency that the effect as an acid component is insufficient. On the other hand, when the content of the structural unit derived from (meth)acrylic acid is greater than 30% by mass, the water solubility becomes too high and the water resistance of the formed coating film etc. is slightly reduced.

[0076] In the polymer dispersant (polymer), the content of the structural unit (1) is 5 to 40% by mass, preferably 10 to 20% by mass, the content of the structural unit (2) is 50 to 80% by mass, preferably 55 to 75% by mass, and the content of the structural unit (3) is 0.5 to 40% by mass, preferably 1 to 31% by mass. It should be noted that the total of the structural unit (1), the structural unit (2), and the structural unit (3) is set to 100% by mass.

[0077] When the content of the structural unit (1) is less than 5% by mass, it cannot be sufficiently adsorbed on the carbon material. On the other hand, when the content of the structural unit (1) is greater than 40% by mass, there is a case of coloring or generating an odor, and there is a case of being easily adsorbed together on the carbon material or acting as an aggregating agent.

[0078] Among the structural units contained in the polymer, the proportion of the structural unit (2) is the largest. Therefore, the polyalkylene glycol chains densely present in the polymer become steric hindrances, which can inhibit the approach between the dispersed carbon materials and make them stably dispersed. When the content of the structural unit (2) is less than 50% by mass, there is a case where the steric hindrance is insufficient and it is difficult to dissolve in water. On the other hand, when the content of the structural unit (2) is greater than 80% by mass, the monomer 2 with slightly lower reactivity does not polymerize and is likely to remain. It should be noted that when the content of the structural unit (3) is greater than 40% by mass, the proportion of other structural units will relatively decrease, so the function as a dispersant will be reduced.

[0079] The number-average molecular weight of the polymer used as a polymer dispersant is 5,000 to 20,000, preferably 10,000 to 15,000. When the number-average molecular weight of the polymer is less than 5,000, the amount of the structural unit (2) derived from monomer 2 as a macromonomer decreases, so the dispersion stability becomes insufficient. On the other hand, when the number-average molecular weight of the polymer is greater than 20,000, the viscosity of the obtained carbon material dispersion may become too high, and the amount of the necessary polymer dispersant may become too large. In this specification, the number-average molecular weight is a value in terms of polystyrene measured by gel permeation chromatography.

[0080] The above polymer that can be used as a polymer dispersant can be produced by a conventionally well-known radical polymerization method or a living radical polymerization method. Among them, production by a living radical polymerization method is preferred because it can control the molecular weight of the main chain and can form an AB block copolymer according to the monomer addition method.

[0081] As the living radical polymerization method, there are a polymerization method using a chain transfer agent such as mercaptan to adjust the molecular weight, an atom transfer radical polymerization method (ATRP method), a reversible addition-fragmentation chain transfer polymerization method (RAFT method), a nitroxide method (NMP method), an organotellurium method (TERP method), an iodine transfer polymerization method (ITP method), a reversible transfer catalyst polymerization method (RTCP method), a reversible catalyst medium polymerization method (RCMP method), etc.

[0082] There are no particular limitations on the polymerization conditions and the like. An azo-based radical generator, a peroxide-based radical generator, a photosensitizer, etc. can be added to the reaction system. The polymerization form can be solvent-free, solution polymerization, emulsion polymerization, etc. Among them, solution polymerization is preferred, and further preferably solution polymerization is carried out in the above-mentioned water-soluble organic solvent that can be miscible with the carbon material dispersion. By carrying out solution polymerization in a water-soluble organic solvent, the obtained polymer solution can be directly mixed with the carbon material dispersion.

[0083] By polymerizing monomer 1, monomer 2, and monomer 3 by solution polymerization or the like, a desired polymer can be obtained. In addition, after polymerizing monomer 1, monomer 2, and monomer 3, a halogenated alkyl such as chlorobenzyl methane, chloromethyl naphthalene, chloromethyl anthracene, chloromethyl pyrene, chloromethyl naphthalene, etc. can be added to the reaction system to quaternize the amino group derived from monomer 1. Furthermore, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(heptafluorobutanesulfonyl)imide, etc. can be added to carry out ion exchange on the quaternary ammonium salt to form a sulfonylimide salt. The dispersant used in the present invention can be used without particular limitation within the range that can stably disperse carbon nanotubes. As the dispersant, surfactants and polymer-type dispersants mainly classified into anionic, cationic, nonionic, and amphoteric can be used.

[0084] On the other hand, when the liquid medium is an organic solvent, the dispersant is preferably a polymer dispersant. Moreover, the dispersant is preferably a polymer comprising 3 to 55% by mass of a structural unit (A) derived from a monomer A represented by the following general formula (A), 45 to 90% by mass of a structural unit (C) derived from a monomer C represented by the following general formula (C), and 0.5 to 20% by mass of a structural unit (D) derived from a monomer D copolymerizable with these monomers.

[0085]

[0086] (In the foregoing general formula (A), R represents a hydrogen atom or a methyl group, A represents O or NH, B represents an ethylene group or a propylene group, R 1 and R 2 each independently represent a methyl group or an ethyl group, Ar represents a phenyl group, a naphthyl group, an anthracenyl group, or a pyrenyl group, and X represents a chlorine atom, a bromine atom, bis(trifluoromethyl)sulfonylimide, or bis(nonafluorobutanesulfonyl)imide)

[0087]

[0088] (In the foregoing general formula (C), R represents a hydrogen atom or a methyl group, A represents O or NH, Q represents an ethylene group or a methylethylene group, Y represents O, NHCOO, or NHCONH, m and n each independently represent an average repeating unit number of 0 or more and m + n = 20 to 100, and R 3 represents an alkyl group, an aryl group, or an alkylaryl group having 1 to 18 carbon atoms)

[0089] The structural unit (A) is a structural unit having a quaternary ammonium salt group derived from the monomer A. It is considered that the quaternary ammonium salt group in the structural unit (A) adsorbs to the carbon material, thereby contributing to the improvement of the dispersibility of the carbon material in a liquid medium containing an organic solvent. It is also considered that one of the substituents bonded to the nitrogen atom of the quaternary ammonium salt group is an arylmethyl group (-CH 2 -Ar). The aromatic ring of this arylmethyl group is affinity with the carbon material, improving the dispersibility of the carbon material. If the carbon numbers of R 1 and R 2 in the general formula (A) are too large, the arylmethyl group will be destabilized due to steric hindrance and it will be difficult to form a quaternary ammonium salt group. Therefore, R 1 and R 2 in the general formula (A) must each independently be a methyl group or an ethyl group.

[0090] The quaternary ammonium group is an ionic functional group. Therefore, it is expected that a polymer (polymeric dispersant) having a structural unit (A) with this quaternary ammonium group will exhibit conductivity through water adsorption and ionic conduction. That is, by using a polymer having a structural unit (A) as a polymeric dispersant, it is expected to prepare a carbon material dispersion capable of forming a coating film with suppressed reduction in conductivity.

[0091] Monomer A is preferably a monomer represented by the following general formula (A-1).

[0092]

[0093] (In the aforementioned general formula (A-1), R 1 and R 2 each independently represent a methyl group or an ethyl group, Ar represents a phenyl group, a naphthyl group, an anthracenyl group, or a pyrenyl group, and X represents a chlorine atom, a bromine atom, bis(trifluoromethyl)sulfonimide, bis(nonafluorobutanesulfonyl)imide)

[0094] Examples of the monomer represented by the general formula (A-1) include dimethylnaphthylmethyl ethylammonium chloride methacrylate, dimethylnaphthylmethyl ethylammonium bromide methacrylate, dimethylnaphthylmethyl ethylammonium bis(trifluoromethyl)sulfonimide methacrylate, dimethylnaphthylmethyl ethylammonium bis(nonafluorobutanesulfonyl)imide methacrylate, diethylnaphthylmethyl ethylammonium chloride methacrylate, diethylnaphthylmethyl ethylammonium bromide methacrylate, diethylnaphthylmethyl ethylammonium bis(trifluoromethyl)sulfonimide methacrylate, diethylnaphthylmethyl ethylammonium bis(nonafluorobutanesulfonyl)imide methacrylate, anthrylmethyldimethylmethyl ethylammonium chloride methacrylate, anthrylmethyldimethylmethyl ethylammonium bromide methacrylate, anthryldimethylmethyl ethylammonium bis(trifluoromethyl)sulfonimide methacrylate, anthryldimethylnaphthyl ethylammonium bis(nonafluorobutanesulfonyl)imide methacrylate, diethylpyrenylmethyl ethylammonium chloride methacrylate, diethylpyrenylmethyl ethylammonium bromide methacrylate, diethylpyrenylmethyl ethylammonium bis(trifluoromethyl)sulfonimide methacrylate, diethylpyrenylmethyl ethylammonium bis(nonafluorobutanesulfonyl)imide methacrylate, etc.

[0095] The polymeric dispersant is preferably a polymer further having a structural unit (B) derived from a monomer B represented by the following general formula (B). By using a polymer further having a structural unit (B) as a polymeric dispersant, the dispersibility of the carbon material can be further improved. It should be noted that by quaternizing the amino group in the structural unit (B), the quaternary ammonium group in the structural unit (A) can be formed.

[0096]

[0097] (In the aforementioned general formula (B), R represents a hydrogen atom or a methyl group, A represents O or NH, B represents an ethylene group or a propylene group, R 1 and R 2 each independently represents a methyl group or an ethyl group)

[0098] The structural unit (B) has an amino group belonging to a basic group. Therefore, it is considered that carboxyl groups and phenolic hydroxyl groups formed on the surface of the carbon material by oxidation or the like are ionically bonded to the amino group in the structural unit (B), so that the polymer dispersant is easily adsorbed on the carbon material, and the dispersibility of the carbon material is further improved. Furthermore, it is considered that the dispersibility of the carbon material is further improved according to the synergistic effect of the quaternary ammonium salt group in the structural unit (A) and the polycyclic aromatic group constituting the quaternary ammonium salt group on the adsorption of the carbon material.

[0099] Monomer B is preferably a monomer represented by the following general formula (B-1).

[0100]

[0101] (In the aforementioned general formula (B-1), R 1 and R 2 each independently represents a methyl group or an ethyl group)

[0102] Examples of the monomer represented by the general formula (B-1) include dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.

[0103] The structural unit (C) is a structural unit having a polyalkylene glycol chain derived from a monomer C belonging to a so-called macromonomer. The polymer dispersant having this structural unit (C) is a polymer having a structure in which a polyalkylene glycol chain is grafted. Moreover, the polyalkylene glycol chain is a molecular chain that can be dissolved in an organic solvent as a dispersion medium. In the general formula (C), the urethane bond (NHCOO) and urea bond (NHCONH) represented by Y are hydrogen-bonded to the hydrogen atoms constituting hydroxyl groups and the like generated on the surface of the carbon material by modification. Therefore, the polymer dispersant is as follows: the polyalkylene glycol chain belonging to the graft chain is dissolved in the organic solvent as the dispersion medium, and the urethane bond (NHCOO) and urea bond (NHCONH) in the structural unit (C) and the main chain containing the structural unit (A) are adsorbed on the carbon material. Moreover, the dissolved polyalkylene glycol chain becomes a steric hindrance between the particulate carbon materials and repels them, so that the carbon material can be stably dispersed in the liquid medium well for a long time.

[0104] In the general formula (C), m is the average number of repeating units of propyleneoxy (-CH(CH 3 )CH 2 O-), and n is the average number of repeating units of ethyleneoxy (-CH 2 CH 2The average number of repeating units of O-). Moreover, m and n are independently values of 0 or more, and m + n = 20 to 100, preferably m + n = 35 to 100. That is, the molecular weight of the polyalkylene glycol chain is preferably 880 to 5800, more preferably 1540 to 5800. It should be noted that in the general formula (C), R 3 The alkyl group having 1 to 18 carbon atoms represented is preferably methyl, ethyl, propyl, butyl, dodecyl, stearyl, phenyl, naphthyl, or nonylphenyl.

[0105] Monomer C is preferably represented by the following general formula (C-1).

[0106]

[0107] (In the above general formula (C-1), Y represents NHCOO or NHCONH, m and n independently represent the average number of repeating units of 0 or more, and m + n = 20 to 100, R 3 represents an alkyl group, aryl group, or alkylaryl group having 1 to 18 carbon atoms)

[0108] As the monomer represented by the general formula (C-1), examples include: a macromonomer in which isocyanatomethacryloyloxyethyl ester is reacted with a glycol monoalkyl ether such as polyethylene glycol monomethyl ether, polyethylene glycol polypropylene glycol monobutyl ether, polypropylene glycol monomethyl ether, or polyethylene glycol monolauryl ether, and Y is a urethane bond (NHCOO); a macromonomer in which isocyanatomethacryloyloxyethyl ester is reacted with a monoether monoamine such as polyethylene glycol polypropylene glycol monoamine, and Y is a urea bond (NHCONH); etc.

[0109] In the general formulas (C) and (C-1), Y is preferably a urea bond (NHCONH) that does not require a catalyst when an isocyanate reacts with an amine. In addition, the polyalkylene glycol chain in the general formulas (C) and (C-1) is preferably a random copolymer of propylene oxide and ethylene oxide. Furthermore, in the general formulas (C) and (C-1), R 3 is preferably methyl. It should be noted that the molecular weight of the polyalkylene glycol chain is preferably 2000 to 4000, and preferably m + n = 36 to 90.

[0110] The structural unit (D) is a structural unit derived from monomer D capable of reacting with the above monomer. As monomer D, examples include (meth)acrylic acid-based monomers such as (meth)acrylic acid and (meth)acrylate; vinyl monomers such as styrene, vinyltoluene, vinylpyridine, vinylcaprolactone, vinylimidazole, α-methylstyrene, and vinyl acetate; etc. Among them, from the viewpoint of facilitating the control of the molecular weight, it is preferable to use α-methylstyrene as monomer D.

[0111] In the polymer dispersant (polymer), the content of structural unit (A) is 3 to 55% by mass, preferably 5 to 50% by mass. If the content of structural unit (A) is less than 3% by mass, the adsorption to the carbon material becomes insufficient. On the other hand, if the content of structural unit (A) exceeds 55% by mass, the solubility in the organic solvent becomes insufficient.

[0112] In the polymer, the content of structural unit (B) is preferably 30% by mass or less, more preferably 2 to 25% by mass. It should be noted that the amine value of the polymer is 100 mgKOH / g or less, preferably 3 to 90 mgKOH / g. If the content of structural unit (B) exceeds 30% by mass, the polymer may be colored.

[0113] In the polymer, the content of structural unit (C) is 45 to 90% by mass, preferably 50 to 85% by mass. That is, structural unit (C) is the structural unit that is contained in the polymer in a relatively large amount. By containing a relatively large amount of structural unit (C), the polyalkylene glycol chains are arranged densely. Therefore, when the polymer as the polymer dispersant adsorbs to the carbon material, the densely arranged polyalkylene glycol chains become steric hindrance, preventing the carbon materials from approaching each other, and the carbon materials can be stably dispersed.

[0114] If the content of structural unit (C) in the polymer is less than 45% by mass, sufficient steric hindrance cannot be formed, and it becomes difficult to improve the dispersibility. On the other hand, if the content of structural unit (C) exceeds 90% by mass, the reactivity of monomer C belonging to the macromonomer is slightly lacking, and therefore, it may remain unreacted and not polymerize.

[0115] In the polymer, the content of structural unit (D) is 0.5 to 20% by mass, preferably 0.6 to 16% by mass. If the content of structural unit (D) exceeds 0.5% by mass, the content of the other structural units relatively decreases, and thus the function as a dispersant is reduced.

[0116] Monomer A, monomer B, and monomer C are represented by general formula (A-1), general formula (B-1), and general formula (C-1) respectively. When monomer D contains α-methylstyrene, even when the carbon material is at a high concentration, it is less likely to aggregate again, and a more stably dispersed carbon material dispersion can be formed, so it is preferred.

[0117] The polystyrene-reduced number average molecular weight (Mw) of the polymer used as the polymer dispersant, measured by gel permeation chromatography (GPC), is 5,000 to 20,000, preferably 10,000 to 15,000. If the number average molecular weight of the polymer is less than 5,000, the amount of the structural unit (C) derived from the monomer C belonging to the macromonomer is small, and sufficient dispersion stability cannot be obtained. On the other hand, if the number average molecular weight of the polymer exceeds 20,000, the amount of the polymer dispersant required to disperse the carbon material becomes excessively large, and the viscosity of the obtained carbon material dispersion becomes excessively high.

[0118] The polymer belonging to the polymer dispersant can be synthesized by a conventionally known method. For example, it can be synthesized by a conventionally known radical polymerization method; a polymerization method using a chain transfer agent such as mercaptan to adjust the molecular weight, an atom transfer radical polymerization method (ATRP method), a reversible addition-fragmentation chain transfer polymerization method (RAFT method), a nitroxide method (NMP method), an organotellurium method (TERP method), an iodine transfer polymerization method (ITP method), a reversible transfer catalyst polymerization method (RTCP method), a reversible catalyst medium polymerization method (RCMP method), or other living radical polymerization methods. Among them, the living radical polymerization method is preferred in terms of making the molecular weight of the main chain more uniformly arranged and forming an A-B block copolymer according to the addition method.

[0119] The polymerization can be either thermal polymerization or photopolymerization, and an azo-based radical initiator, a peroxide-based radical initiator, a photosensitizer, etc. can be added to the polymerization reaction system. The polymerization form can be solvent-free, solution polymerization, or emulsion polymerization, and solution polymerization is preferred. By using the same organic solvent as that used in the carbon material dispersion for solution polymerization, the polymer after the polymerization reaction can be directly used for the carbon material dispersion, so it is preferred.

[0120] For example, by subjecting the above-mentioned respective monomers to solution polymerization, the target polymer (polymer dispersant) can be obtained. It should be noted that by adding an alkyl halide such as benzyl chloride, naphthylmethyl chloride, ethynylmethyl chloride, pyrenylmethyl chloride, or naphthylmethyl bromide to the reaction solution obtained by polymerizing monomers B to D, the amino group in the structural unit (B) can be quaternized, and the structural unit (B) can be converted into the structural unit (A). Furthermore, by adding lithium bis(trifluoromethylsulfonyl)imide, lithium bis(heptafluorobutanesulfonyl)imide, etc., the anion (Cl - 、Br - ) constituting the quaternary ammonium salt can be ion-exchanged.

[0121] The content of the dispersant in terms of solid content is preferably in the range of 10 to 500 parts by mass, more preferably 30 to 500 parts by mass, relative to 100 parts by mass of the carbon material. In addition, the content of the carbon material in the carbon material dispersion is preferably 10% by mass or less, more preferably 5% by mass or less. The content of the dispersant in the carbon material dispersion is preferably 30% by mass or less, more preferably 15% by mass or less. By making the content of the dispersant relative to the carbon material within the above range, a carbon material dispersion in which the carbon material is more stably dispersed can be formed. When the amount of the dispersant relative to the carbon material is too small, the dispersant cannot sufficiently cover the surface of the carbon material, and the dispersibility may sometimes become insufficient. On the other hand, when the amount of the dispersant relative to the carbon material becomes too large, the carbon material dispersion tends to thicken, and the ratio of the carbon material in the solid content may sometimes become relatively low. In addition, when the dispersion is used as ink or a coating material, the physical properties such as the strength and conductivity of the formed coating film may sometimes be slightly reduced.

[0122] (Additives, etc.)

[0123] The carbon material dispersion can further contain additives, resins, etc. Examples of the additives include water-soluble dyes, pigments, ultraviolet absorbers, light stabilizers, antioxidants, leveling agents, defoamers, preservatives, fungicides, photoinitiators, and other pigment dispersants. Examples of the resins include polyolefin resins, polyhalogenated olefin resins, polyester resins, polyamide resins, polyimide resins, polyether resins, polyvinyl resins, polystyrene resins, polyvinyl alcohol resins, polymethacrylate resins, polyurethane resins, polyepoxy resins, polyphenolic resins, polyureas, polyethersulfone resins, etc.

[0124] The carbon material dispersion preferably contains a defoamer as an additive according to the apparatus used in the wetting and dispersion process. If a defoamer is contained, foaming during the dispersion treatment can be suppressed. Therefore, the shear force, collision force, etc. imparted during the dispersion treatment can effectively act, and a dispersion with more excellent dispersibility can be formed.

[0125] (Carbon material dispersion)

[0126] The absorbance of the dispersion of the carbon material containing carbon nanotubes depicts a gentle curve at wavelengths from 300 nm to 1000 nm. Among them, this curve (absorbance curve) varies greatly depending on the dispersion state of the carbon nanotubes. For example, when the amount of finely dispersed carbon nanotubes is large, the absorbance on the short wavelength side shows a large value. On the other hand, when the amount of aggregates of carbon nanotubes is large, the absorbance on the long wavelength side shows a large value. Therefore, the absorbance ratio (A L ) obtained by dividing the absorbance on the short wavelength side (A H ) by the absorbance on the long wavelength side (A L / A H)It can well reflect the dispersion state of carbon materials in a liquid medium. That is, the thinner and more uniformly the carbon nanotubes are dispersed, the larger the absorbance ratio; when the carbon nanotubes aggregate, the absorbance ratio is small.

[0127] Wavelength W as a reference M Set as the wavelength W on the short-wavelength side L And the wavelength W on the long-wavelength side H The median value of (W M =(W L +W H ) / 2). In the wavelength region near the median value, it is basically not affected by the dispersion state of carbon materials. Therefore, it is suitable as a reference for evaluating the dispersibility of carbon materials.

[0128] The wavelength W on the short-wavelength side L Is arbitrarily selected from the range of 350 - 550 nm, preferably from the range of 350 - 450 nm, and more preferably from the range of 350 - 400 nm. The change in absorbance at wavelengths within the above range is clear, and there is little noise and specific peak change, so the measurement can be carried out stably. If it is less than 350 nm, the absorption and scattering of light by fine particles irregularly have an impact, and as the dispersion progresses, the peak will change significantly, making it difficult to form an accurate index. On the other hand, if it exceeds 550 nm, the change in absorbance becomes unclear.

[0129] The wavelength W on the long-wavelength side H Is arbitrarily selected from the range of 650 - 850 nm, preferably from the range of 700 - 850 nm, and more preferably from the range of 700 - 800 nm. If it is a wavelength within the above range, the absorbance of particles with a small proportion of absorption components and a large proportion of scattering components can be confirmed. In addition, there is little noise and specific peak change, so the measurement can be carried out stably. If it exceeds 850 nm, noise will be mixed in the peak, making it difficult to measure an accurate value. On the other hand, less than 650 nm is an unsuitable range as an index.

[0130] Wavelength W L And the wavelength W H The difference is preferably 100 nm or more, and more preferably 200 nm or more. By making the difference between wavelength W L And wavelength W H Be 100 nm or more, the dispersibility of carbon materials can be read more accurately. If the difference between wavelength W L And wavelength W H Is too small, it may be difficult to evaluate the dispersion state of carbon materials with good precision.

[0131] The absorbance of the dispersion varies according to the content (concentration) of the carbon material. Therefore, the absorbance of the diluted dispersion prepared by diluting the dispersion is measured. As the diluent for diluting the dispersion, a blank solution having the same composition as the carbon material dispersion to be measured except that it does not contain a carbon material is preferably used. By using such a blank solution, the influence of diffusion, re-aggregation of fine particles, and the environment on the absorbance is suppressed, and it is not easily affected by the polymer dispersant sometimes used as a dispersant, and the absorbance can be measured more accurately.

[0132] In order to accurately measure the absorbance, it is generally preferable that the content of the carbon material in the sample solution (diluted dispersion) is in the range of 0.001 to 0.01% by mass. If it exceeds 0.01% by mass, the amount of laser scattered light transmitted during measurement is small, and it may be difficult to accurately perform the measurement. On the other hand, if it is less than 0.001% by mass, the value of the absorbance becomes excessively small, and accurate evaluation and comparison may sometimes become difficult.

[0133] The absorbance of the diluted dispersion obtained by diluting with a diluent containing a liquid medium at wavelength W M is 1.2 to 2.2, preferably 1.5 to 2.0. If the absorbance of the diluted dispersion at wavelength W M is less than 1.2, it becomes difficult to judge the dispersion state. On the other hand, it is difficult to accurately measure the absorbance exceeding 2.2.

[0134] The absorbance A of the diluted dispersion at wavelength W L with respect to wavelength W L and the absorbance A H at wavelength W H The ratio (A L / A H ) value varies according to wavelength W H and W L . For example, when the value of “A L / A H ” at wavelength W L = 380 nm and wavelength W H = 780 nm is “1.60”, the value of “A L / A H ” at wavelength W L = 400 nm and wavelength W H = 700 nm is “1.44”, and the value of “A L / A H ” at wavelength W L = 350 nm and wavelength W H = 800 nm is “1.78”. In addition, when wavelength W L = 380 nm and wavelength W H = 780 nm, the value of “A L / AH When the value of "" is "1.65", the wavelength W L = 400 nm and the wavelength W H = 700 nm, the value of "A L / A H " is "1.48", and when the wavelength W L = 350 nm and the wavelength W H = 800 nm, the value of "A L / A H " is "1.85".

[0135] The absorbance of the dispersion liquid at the wavelength W L is a physical property value that is an index of the dispersion state of the carbon material. On the other hand, the absorbance of the dispersion liquid at the wavelength W H is a physical property value that is an index of the aggregation state of the carbon material. Taking the wavelength W L belonging to the median value of W H as a reference, so that the absorbance at this wavelength W M becomes 1.2 to 2.2, the absorbance A M of the diluted dispersion liquid obtained by diluting with a diluent containing a liquid medium at the wavelength W L is obtained. The ratio (A L relative to the absorbance A H at the wavelength W H / A L / A H ) value can accurately evaluate the dispersion state of the carbon material in the dispersion liquid.

[0136] For the dispersion liquid, when the wavelength W L is 380 nm, the wavelength W H is 780 nm, and the wavelength W M is 580 nm, and the absorbance at the wavelength W M is 1.5 to 2.0 (preferably 1.8 ± 0.02), the absorbance A L relative to the absorbance A H ratio (A 380 / A 780 ) is preferably 1.60 or more, more preferably 1.65 or more. By making the value of the absorbance ratio (A 380 / A 780 ) within the above range, even if the types and addition amounts of the carbon material and the dispersant change, a dispersion liquid with more excellent viscosity stability can be formed and substantially no coarse aggregates are contained.

[0137] The absorbance ratio (A 380 / A 780) If the value is excessively small, the carbon nanotubes are not in a state of being thin and uniformly dispersed. Therefore, the viscosity stability of the dispersion liquid is low, and there are many large aggregates. The absorbance ratio (A 380 / A 780 ) of the dispersion liquid of the present invention that is 1.40 or more contains a carbon material including carbon nanotubes in a state of being thin and uniformly dispersed, has good viscosity stability, and substantially does not contain large aggregates. Even when it contains fine aggregates, the amount is extremely small.

[0138] When the carbon material is dispersed in the liquid medium by dispersion treatment, at the initial stage of the dispersion treatment, there are many aggregates of the carbon material in the liquid medium, so the absorbance ratio is small. Then, as the dispersion treatment progresses, the dispersant adsorbs to the carbon nanotubes, and the aggregates are slowly loosened, and the absorbance ratio increases. If the size of the short side of the aggregate becomes less than 100 μm, the absorbance ratio (A 380 / A 780 ) becomes 1.60 or more. When the dispersion treatment is further carried out, the carbon nanotubes are in a state of being more uniformly dispersed in the liquid medium, and the absorbance ratio (A 380 / A 780 ) becomes 1.65 or more. However, when the dispersion treatment is carried out excessively, the carbon nanotubes with damaged structures will aggregate again, and the absorbance ratio (A 380 / A 780 ) decreases to less than 1.40.

[0139] The viscosity of the dispersion liquid of the present invention is not likely to change even after a long time, and the viscosity stability (storage stability) is excellent. Specifically, taking the viscosity (mPa·s) at 25°C of the dispersion liquid just prepared (dispersed) as a reference, the change rate of the viscosity (mPa·s) at 25°C of the dispersion liquid after 10 days under room temperature (25°C) conditions is generally 15% or less, preferably 10% or less, and more preferably 5% or less.

[0140] When aggregates with a short side of 100 μm or more are present in the dispersion, when the dispersion is used for various purposes, it becomes difficult to exhibit the original properties of the carbon nanotubes, such as electrical conductivity and thermal conductivity, and the growth and sedimentation of aggregates occur, and the viscosity stability and storage stability tend to be easily reduced. For example, when a dispersion containing aggregates with a short side of 100 μm or more is used as a coating material, uniform coating tends to be difficult. In contrast, the dispersion of the present invention substantially does not contain large aggregates formed from a carbon material containing carbon nanotubes. Specifically, when observing the freshly prepared (dispersed) dispersion and the dispersion after 10 days at room temperature (25 °C) 5 times at a magnification of 200 times using an optical microscope, usually no aggregates with a short side of 100 μm or more can be confirmed. Preferably, the number (average value) of aggregates with a short side of 20 μm or more is 10 or more in each observation. More preferably, the number (average value) of aggregates with a short side of 20 μm or more is 1 or more and less than 10 in each observation, and particularly preferably, no aggregates with a short side of 20 μm or more can be confirmed even after observing 5 times.

[0141] (Method for manufacturing a carbon material dispersion)

[0142] The carbon material dispersion can be manufactured as follows: Using a dispersant, according to a conventionally well-known method, after pre-wetting a carbon material containing carbon nanotubes in a liquid medium, dispersion is carried out, thereby it can be manufactured. For example, the following can be used: stirring with a magnetic stirrer, stirring with a dissolver, kneading in a three-roll mill, ultrasonic dispersion, bead mill dispersion, wetting methods and dispersion methods using an emulsifying device, a homogenizer, etc. For the simplicity of the process, it is preferable to stir and wet it with a magnetic stirrer, a dissolver, and a homogenizer, and it is preferable to carry out dispersion in combination with a high-pressure homogenizer. For example, it is preferable to carry out dispersion using a bead mill using beads with a small particle size. In addition, considering the damage to carbon materials such as carbon nanotubes, a method combining wetting and stirring with high dispersion can be combined.

[0143] <Products>

[0144] In the above carbon material dispersion of the present invention, the carbon material containing carbon nanotubes is well dispersed without substantially generating large aggregates, and the viscosity stability is excellent. Therefore, by exhibiting this characteristic, the following products can be provided. That is, any product (first product) containing the aforementioned carbon material dispersion, such as a coating, ink, coating agent, resin molding material, conductive material, heat conductive material, and antistatic material can be provided. In addition, any product (second product) of a battery material and a mechanical component having a coating film formed from the aforementioned carbon material dispersion can be provided.

[0145] As methods for preparing coatings and inks, for example, there are the following methods: a method of adding a solvent, a resin, various additives, etc. to a dispersion so as to form a coating composition or an ink composition; a method of adding a dispersion to a commercially available coating or ink; etc. As a method for manufacturing a resin molded article in which a carbon material containing carbon nanotubes is dispersed, for example, there are the following methods: a method of mixing a molten resin material with a dispersion and then removing the liquid medium; a method of adding a dispersion to a resin material in a fine powder state and then removing the liquid medium or precipitating the carbon material; etc.

[0146] Examples

[0147] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. It should be noted that "parts" and "%" in the examples and comparative examples are based on mass unless otherwise specified.

[0148] <Preparation of materials>

[0149] Prepare the following carbon materials, dispersants, and defoamers.

[0150] (Carbon material)

[0151] [Carbon nanotubes (CNT)]

[0152] · CNT-A: Multi-walled CNT, average diameter 30 - 50 nm, average length 5 - 12 μm, trade name "s40", manufactured by SUSN Co., Ltd.

[0153] · CNT-B: Multi-walled CNT, average diameter 15 nm, average length 3 μm, trade name "VGCF-X", manufactured by Showa Denko K.K.

[0154] · CNT-C: Multi-walled CNT, average diameter 9.5 nm, average length 1.5 μm, trade name "NC7000", manufactured by nanocyl

[0155] · CNT-D: Multi-walled CNT, average diameter 14 - 16 nm, average length 90 - 100 μm, trade name "K-nanos400T", manufactured by KUMHO

[0156] · CNT-E: Multi-walled CNT, average diameter 6 - 9 nm, average length 100 - 200 μm, trade name "JENOTUBE8c", manufactured by JEIO

[0157] · CNT-F: Multi-walled CNT, average diameter 5 - 7 nm, average length 50 - 150 μm, trade name "JENOTUBE 6A", manufactured by JEIO

[0158] · CNT-G: Single-walled CNT, average diameter 3 - 5 nm, average length 100 - 600 μm, trade name "SG-101", manufactured by ZEON CORPORATION

[0159] [Carbon black (CB)]

[0160] · Average particle size 23 nm

[0161] (Dispersant)

[0162] · Dispersant a: Trade name "DYSPERBYK-2012", manufactured by BYK-Chemie, solid content 40%

[0163] · Dispersant b: Trade name "DYSPERBYK-102", manufactured by BYK-Chemie, solid content 99%

[0164] · Dispersant c: Trade name "DYSPERBYK-9077", manufactured by BYK-Chemie, solid content 100%

[0165] · Dispersant d: Trade name "Flowlen GW-1500", manufactured by Kyoeisha Chemical Co., Ltd., solid content 100%

[0166] · Dispersant e: Trade name "Dispex Ultra PA4550", manufactured by BASF SE, solid content 50%

[0167] · Dispersant f: Trade name "TEGODispers 670", manufactured by Evonik, solid content 40%

[0168] · Dispersant g: Sodium dodecyl sulfate (surfactant), FUJIFILM Wako Chemicals Corporation

[0169] · Dispersant h: Trade name "Sunrose F01MC", manufactured by Nippon Paper Industries Co., Ltd., sodium carboxymethyl cellulose, viscosity of 1 mass% aqueous solution 7 - 13 mPa·s, degree of etherification 0.65 - 0.75

[0170] (Defoamer)

[0171] · Trade name "BYK-028", manufactured by BYK-Chemie

[0172] <Manufacture of dispersant>

[0173] Manufacture dispersants A1 - A3, dispersants B1 - B3 and dispersants C1 - C3 according to the steps shown below.

[0174] (Dispersant A1)

[0175] (a) Synthesis of macromonomer

[0176] In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, 142.5 parts (0.067 mol) of a mono-terminal amino group-terminated polypropylene glycol polyethylene glycol monomethyl ether copolymer (M41) (trade name “Genami M41 / 2000”, manufactured by Clariant, measured amine value 26.4 mgKOH / g) was added and stirred. 10.4 parts (0.067 mol) of 2-isocyanatoethyl methacrylate (MOI) (trade name “Karenz MOI”, manufactured by Showa Denko K.K.) was added to the dropping funnel and added dropwise to the reaction apparatus cooled with a water bath over 30 minutes. A part of the reaction solution was sampled and subjected to IR measurement, and disappearance of the absorption of the isocyanate group derived from MOI and formation of a urea bond were confirmed. In addition, the amine value of the product was 0.2 mgKOH / g, and it was confirmed that the reaction between the amino group and the isocyanate group had basically ended. It should be noted that the amine value was measured using an automatic potentiometric titrator with a 0.1 mol / L 2-propanolic hydrochloric acid solution. From the above, it was confirmed that a polypropylene glycol polyethylene glycol copolymer (MC-1) having a methacryloyl group bonded to its mono-terminal was formed. The number-average molecular weight (Mn) of MC-1 in terms of polystyrene measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the eluent was 2,800, and the molecular weight distribution (PDI = weight-average molecular weight (Mw) / number-average molecular weight (Mn)) was 1.09. MC-1 is a macromonomer corresponding to monomer 2 represented by the general formula (1), and the number of repeating units n H is more than 1 / 2 of the total number of repeating units n T above.

[0177] (b) Synthesis of dispersant

[0178] In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 95 parts of diethylene glycol monobutyl ether (BDG), 70 parts of MC-1, 2.5 parts of α-methylstyrene (αMS), 10.5 parts of styrene (St), and 17 parts of 4-vinylpyridine (4VP) were added, and the mixture was heated to 75 °C while bubbling nitrogen. At the moment when the temperature reached 70 °C, 5 parts of 2,2'-azobis(isobutyric acid) dimethyl ester (V-601) (trade name "V-601", FUJIFILM Wako Chemicals Corporation) was added, and polymerization was carried out at 75 °C for 4 hours. Further, 2.5 parts of V-601 was added, and polymerization was carried out at 75 °C for 4 hours to obtain a liquid containing a polymer (dispersant A1). The Mn of the dispersant A1 (polymer) was 9600, the PDI was 1.83, the peak top molecular weight (PT) was 22700, and substantially no peak derived from MC-1 used as a raw material was confirmed. In addition, the amine value (in terms of pure resin component) of the dispersant A1 was 86.2 mgKOH / g. The solid content of the liquid containing the dispersant A1 measured using a moisture meter was 50.4%.

[0179] (Dispersant A2)

[0180] In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, 100 parts of the dispersant A1 was added. After adding 30 parts of BDG and diluting, the mixture was stirred at room temperature for 10 minutes for homogenization to obtain a solution. In the obtained solution, 0.081 mol of amino group derived from 4VP was present. At room temperature, a solution containing 10.25 g of BDG and 10.25 g (0.081 mol) of benzyl chloride (BzCl) was added dropwise from the dropping funnel over 30 minutes. After the dropwise addition, the mixture was heated to 80 °C and maintained for 5 hours to obtain a liquid containing a polymer (dispersant A2). The solid content of the liquid containing the obtained dispersant A2 was 40.2%. In addition, it was found that the amine value of the dispersant A2 was substantially 0 mgKOH / g, the reaction proceeded quantitatively, and all the amino groups derived from 4VP were quaternized.

[0181] (Dispersant A3)

[0182] In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 95.0 parts of BDG, 70 parts of MC-1, 2.5 parts of αMS, 10.4 parts of St, 7.7 parts of methacrylic acid (MAA), and 9.4 parts of 4VP were added, and the mixture was heated to 75 °C while bubbling nitrogen. At the moment when the temperature reached 70 °C, 5 parts of V-601 were added, and polymerization was carried out at 75 °C for 4 hours. Further, 2.5 parts of V-601 were added, and polymerization was carried out at 75 °C for 4 hours to obtain a liquid containing a polymer (dispersant A3). The Mn of dispersant A3 (polymer) was 11,900, the PDI was 1.88, the PT was 25,900, and substantially no peak derived from MC-1 used as a raw material was confirmed. In addition, the amine value (in terms of pure resin component) of dispersant A3 was 50.0 mgKOH / g, and the acid value (in terms of pure resin component) was 50.0 mgKOH / g. This polymer is an amphoteric polymer dispersant having amino and carboxyl groups in its structure. The solid content of the liquid containing dispersant A3 was 50.9%.

[0183] (Synthesis of polymer dispersant B1)

[0184] (a) Synthesis of macromonomer

[0185] In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, 400 parts (0.2 mol) of a mono-terminal amino-polypropylene glycol polyethylene glycol monomethyl ether copolymer (trade name “JEFFAMINE M2005”, manufactured by Huntsuman Corporation, amine value (measured): 28.05 mgKOH / g) (M2005) and 256.32 parts of propylene glycol monomethyl ether acetate (PGMAc) were added, and the mixture was stirred at room temperature for 10 minutes for homogenization. In another container, 31.04 parts (0.2 mol) of 2-isocyanatoethyl methacrylate (trade name “Karenz MOI”, manufactured by Showa Denko K.K.) (MOI) and 31.04 parts of PGMAc were added to prepare a mixed solution. The prepared mixed solution was added dropwise to the reaction apparatus through the dropping funnel over 30 minutes. Gentle exotherm was observed just after the start of the dropwise addition. Samples were taken and IR measurement was carried out to confirm the disappearance of the absorption of the isocyanate group derived from MOI and the formation of a urea bond, and the formation of a macromonomer (A) having an α,β-unsaturated bond was confirmed. Heating was carried out at 140 °C with a dryer until a constant weight was reached, and the solid content measured and calculated was 60.0%. Hereinafter, the solid content was measured and calculated by this method. The obtained macromonomer (A) was designated as “MAC-1”. The number average molecular weight (Mn 1 ) of MAC-1 in terms of polystyrene measured by GPC (eluent: tetrahydrofuran) was 3,500. Hereinafter, the molecular weights of various polymers were measured under this condition.

[0186] (b) Synthesis of polymer dispersant

[0187] In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 30.8 parts of PGMAc, 179.6 parts of MAC-1, 3.0 parts of α-methylstyrene (αMS), 25.2 parts of styrene (St), and 18.0 parts of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) were added, and nitrogen was bubbled while heating to 70 °C. 3.0 parts of 2,2'-azobis(2-methylpropionitrile) dimethyl ester (trade name "V-601", FUJIFILM Wako Chemicals Corporation) (V-601) was added, and polymerization was carried out at 70 °C for 4 hours. Further, 0.5 part of V-601 was added, and polymerization was carried out at 70 °C for 4 hours to obtain a polymer (dispersant B1) solution. The number average molecular weight (Mn) of dispersant B1 (polymer) was 6400, the molecular weight distribution (dispersion degree (PDI)) was 2.2, and substantially no peak derived from MAC-1 used as a raw material was observed. In addition, the solid content of the solution containing dispersant B1 was 60.8%. Furthermore, using a potentiometric automatic titrator, the amine value of the polymer measured with a 0.1N hydrochloric acid / isopropanol solution as the titrant was 41.9 mgKOH / g. Hereinafter, the amine values of various polymers were measured under this condition.

[0188] (Synthesis of polymer dispersant B2)

[0189] (a) Synthesis of macromonomer

[0190] In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, 100 parts (0.05 mol) of mono-terminal amino polypropylene glycol polyethylene glycol monomethyl ether (trade name "JEFFAMINE M2005", manufactured by Huntsuman Corporation, m + n = 35 (m = 29, n = 6), measured amine value 28.05 mgKOH / g) (M2005) and 100 parts of propylene glycol monomethyl ether acetate (PGMAc) were added, and stirred at room temperature for 10 minutes for homogenization. In another container, 7.75 parts (0.05 mol) of 2-isocyanatoethyl methacrylate (trade name "Karenz MOI", manufactured by Showa Denko K.K.) (MOI) and 7.75 parts of PGMAc were added and mixed to prepare a mixed solution. The prepared mixed solution was added dropwise to the reaction apparatus over 30 minutes to cause reaction. A part of the reaction solution was sampled and subjected to IR measurement, and disappearance of the isocyanate group derived from MOI and formation of a urethane bond were confirmed. In addition, using an automatic potentiometric titrator, the amine value of the product measured with a 0.1 mol / L 2-propanolic hydrochloric acid solution was 0.1 mgKOH / g. Thus, it was confirmed that the reaction between the amino group and the isocyanate group had basically ended. The obtained product was a macromonomer (MCR-1) having a methacryloyl group bonded to a mono-terminal of polypropylene glycol polyethylene glycol monomethyl ether (PPG / PEG). The solid content of the MCR-1 solution measured with a moisture meter was 50.0%. In addition, the number average molecular weight (Mn) of MCR-1 in terms of polystyrene measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as an eluent was 3400.

[0191] (b) Synthesis of polymer dispersant

[0192] In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 77.5 parts of PGMAc, 215.5 parts of the MCR-1 solution, 1.8 parts of α-methylstyrene (αMS), and 44.3 parts (0.281 mol) of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) were added, and heated while bubbling nitrogen. When the internal temperature reached 70 °C, 3.0 parts of 2,2'-azobis(isobutyric acid) dimethyl ester (trade name "V-601", FUJIFILM Wako Chemicals Corporation) (V-601) were added, heated to 75 °C, and polymerized for 4 hours. 0.5 part of V-601 was added, and polymerization was further carried out at 75 °C for 4 hours. The Mn of the product measured by sampling a part of the reaction solution was 7900, the dispersity (PDI) was 1.65, the peak top molecular weight (PT) was 13500, and basically no peak derived from MCR-1 was observed. The solid content of the reaction solution was 50.2%. In addition, the amine value (in terms of pure resin component) of the product was 102.9 mgKOH / g.

[0193] At room temperature, a solution of 7.8 parts of PGMAc and 35.7 parts (0.2819 mol) of benzyl chloride (BzCl) was added dropwise over 30 minutes. After the addition, the mixture was heated to 80 °C and maintained for 5 hours to obtain a liquid containing the polymer dispersant B2. The Mn of the polymer dispersant B2 was 8000, the PDI was 1.53, and the PT was 13700. The solid content of the liquid containing the polymer dispersant B2 was 50.2%. The amine value (in terms of pure resin component) of the polymer dispersant B2 was basically 0 mgKOH / g, confirming that the reaction proceeded almost quantitatively. The obtained polymer dispersant B2 was a resin in which the amino group derived from DMAEMA was almost 100% quaternized with BzCl.

[0194] (Synthesis of polymer dispersant B3)

[0195] In a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 44.3 parts of PGMAc, 216 parts of MCR-1 solution, 1.8 parts of αMS, 12.5 parts of styrene (St), and 31.7 parts (0.202 mol) of DMAEMA were added, and the mixture was heated while bubbling nitrogen. When the internal temperature reached 70 °C, 3.0 parts of V-601 were added, and the mixture was heated to 75 °C and polymerized for 4 hours. Then 0.5 parts of V-601 were added, and polymerization was further carried out at 75 °C for 4 hours. The Mn of the product measured by sampling a part of the reaction solution was 11200, the PDI was 1.86, the PT was 20700, and basically no peak derived from MCR-1 was detected. The solid content of the reaction solution was 50.1%. In addition, the amine value (in terms of pure resin component) of the product was 104.5 mgKOH / g.

[0196] Using 12.6 parts (0.050 mol) of 1-chloromethylpyrene (CMP) instead of BzCl, the quaternization reaction was carried out in the same manner as in the above B2 synthesis example to obtain a liquid containing the polymer dispersant B3. The Mn of the polymer dispersant B3 was 11500, the PDI was 1.85, and the PT was 20800. The solid content of the liquid containing the polymer dispersant B3 was 50.2%. The amine value (in terms of pure resin component) of the polymer dispersant B3 was 53.5 mgKOH / g. The obtained polymer dispersant B3 was a resin in which 25% of the amino group derived from DMAEMA was quaternized with CMP.

[0197] (Dispersant C1)

[0198] In a 1 L stainless steel container equipped with a stirrer, add 400 g of isopropyl alcohol (IPA) and 60 g of water. While cooling the stainless steel container, add 10 g of sodium hydroxide (purity 98%). After cooling the solution to below 25 °C, add 20 g of shredded pulp while stirring. Then, stir and mix for 60 minutes (mercerization) at 15 - 25 °C to prepare alkaline cellulose. Next, cool the stainless steel container and add 30 g of a mixed solution of monochloroacetic acid / isopropyl alcohol = 1:2 while maintaining the temperature at 15 - 25 °C, and stir and mix for 15 minutes. Then, while heating the stainless steel container, raise the temperature of the solution to 70 °C over about 30 minutes. Stir at 65 - 75 °C for 45 minutes to carry out the etherification reaction. After the reaction is completed, neutralize the unreacted sodium hydroxide with acetic acid and separate the product. Wash with a 70% methanol aqueous solution to remove by-products. Dry and pulverize the product to obtain sodium carboxymethyl cellulose (C1). The viscosity of a 1 mass% aqueous solution and the degree of etherification of the obtained sodium carboxymethyl cellulose are shown in Table 1.

[0199] (Dispersants C2, C3)

[0200] As shown in Table 1, change the reaction time of etherification. Except for this, sodium carboxymethyl cellulose (C2, C3) is manufactured according to the same method as dispersant C1. The viscosity of a 1 mass% aqueous solution and the degree of etherification of each are shown in Table 1.

[0201] The degree of etherification is measured with reference to the test method for synthetic detergent JIS-related substances described in Oil Chemistry 38(11), 962 - 967, 1989. Specifically, accurately weigh about 1 g of sodium carboxymethyl cellulose, put it into a porcelain crucible, and heat and ash it at a temperature not exceeding 600 °C (about 550 - 590 °C) for 1 hour. After cooling to room temperature, transfer it to a 500 mL beaker together with the crucible, and add 250 mL of water. Add 50 mL of 0.05 mol / L sulfuric acid aqueous solution and boil for 30 minutes. After cooling to room temperature, titrate the unreacted acid with 0.1 mol / L sodium hydroxide. Use phenolphthalein as the indicator. Record the amount of 0.1 mol / L sodium hydroxide used in the titration as "X" mL, and calculate the degree of etherification (DS) according to the following formula.

[0202] Degree of etherification (DS) = 162X / (10000 - 80X)

[0203] Table 1

[0204]

[0205] <Measurement and evaluation methods>

[0206] (Measurement of absorbance and calculation of absorbance ratio)

[0207] Prepare a blank solution having the same composition as the dispersion except for the absence of carbon materials. Measure the baseline using the prepared blank solution, and on this basis, measure the absorbance of the sample solution. The absorbance of the sample solution is measured using a spectrophotometer (trade name "Hitachi Spectrophotometer U-3310 type", manufactured by Hitachi High-Tech Corporation) equipped with a quartz cuvette with an optical path length of 10 mm. For dilution based on the blank solution, prepare a standard curve plotting the absorbance at a wavelength of 580 nm against the dilution ratio, calculate the dilution ratio at which the aforementioned absorbance becomes 1.8 ± 0.02, and thus prepare a dispersion diluted to the target concentration. Alternatively, it is also possible to adjust to the target carbon component concentration at the stage before dispersion and adjust to the carbon component concentration satisfying the aforementioned absorbance at the initial compounding stage and then perform dispersion. The specific method for preparing the sample solution is as follows: First, collect the dispersion in a plastic bottle (a polyethylene bottle), and based on the dilution ratio obtained from the standard curve, add an appropriate amount of the blank solution. Stir for 30 seconds using a vortex mixer (manufactured by Scientific Industries, Inc.) to obtain a sample solution with an absorbance A at a wavelength of 580 nm 580 of 1.8 ± 0.02. Measure the absorbance A at a wavelength of 380 nm of the obtained sample solution 380 and the absorbance A at a wavelength of 780 nm 780 , and calculate the absorbance ratio (A 380 / A 780 ). It should be noted that for a dispersion prepared with a highly volatile organic solvent, cover the quartz cuvette with a lid and measure the absorbance

[0208] (Evaluation of the dispersion)

[0209] [Measurement of viscosity and evaluation of viscosity stability]

[0210] Using an E-type viscometer equipped with a rotor of 1°34’×R24, measure the viscosity of the dispersion just after dispersion and the dispersion after 10 days (after standing at room temperature for 10 days) under the conditions of a temperature of 25°C and a rotor speed of 100 rpm. It should be noted that for a dispersion with a viscosity less than 25 mPa·s, measure the viscosity using the product named "VISCOMETERTVE-25L" (manufactured by Toki Sangyo Co., Ltd.). In addition, for a dispersion with a viscosity of 25 mPa·s or more, measure the viscosity using the product named "VISCOMETERTVE-25H" (manufactured by Toki Sangyo Co., Ltd.). Then, evaluate the viscosity stability of the dispersion according to the evaluation criteria shown below

[0211] ◎: The change rate of the viscosity after 10 days based on the viscosity just after dispersion is less than 5%

[0212] ○: The change rate of the viscosity 10 days after, based on the viscosity just after dispersion, is 5% or more and less than 10%.

[0213] △: The change rate of the viscosity 10 days after, based on the viscosity just after dispersion, is 10% or more and less than 15%.

[0214] ×: The change rate of the viscosity 10 days after, based on the viscosity just after dispersion, is 15% or more

[0215] [Observation of aggregates]

[0216] Collect the dispersion liquid in a plastic bottle (made of polyethylene), and add a blank liquid and dilute it so that the concentration of the carbon material becomes 0.1 mass%. Stir for 30 seconds using a vortex mixer (manufactured by Scientific Industries, Inc.) to obtain a diluted liquid. Drop 30 μL of the obtained diluted liquid on a glass slide, place a glass cover slip, and then use an optical microscope to observe the presence or absence of aggregates (200 times magnification). For the dispersion liquid just after dispersion and the dispersion liquid 10 days later (left standing at room temperature for 10 days), prepare samples by dropping on the glass slide 5 times each and observe. Evaluate the presence or absence of aggregates according to the following evaluation criteria.

[0217] ◎: In 5 observations, no aggregate with a short side of 20 μm or more is confirmed.

[0218] ○: The number (average value) of aggregates with a short side of 20 μm or more is 1 or more and less than 10 in each observation, and in 5 observations, no aggregate with a short side of 100 μm or more is confirmed.

[0219] △: The number (average value) of aggregates with a short side of 20 μm or more is 10 or more in each observation, and in 5 observations, no aggregate with a short side of 100 μm or more is confirmed.

[0220] ×: In 5 observations, 1 or more aggregates with a short side of 100 μm or more are confirmed.

[0221] <Preparation and evaluation of dispersion liquid (aqueous) (1)>

[0222] (Examples 1 - 17, Comparative Examples 1 - 9)

[0223] In a plastic bottle (made of polyethylene) with a capacity of 100 mL, add each component (other than CNT) shown in Table 2 in the types and amounts indicated. Stir with a magnetic stirrer until it becomes uniform, and then add the CNT shown in Table 2 in the types and amounts indicated and stir further. Add 200 parts of zirconia beads with an average diameter of 0.8 mm, and using SCANDEX (manufactured by SCANDEX LIMITED), perform dispersion treatment for the treatment time shown in Table 2. After that, separate and remove the zirconia beads to obtain a dispersion. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion is shown in Table 2. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of viscosity stability, and the results of aggregate observation are shown in Table 3.

[0224] Table 2

[0225]

[0226] Table 3

[0227]

[0228] <Preparation and Evaluation of Dispersion (Aqueous) (2)>

[0229] (Examples 18 - 24, Comparative Examples 10 - 12)

[0230] In the container of a 1 / 4G sand mill (manufactured by Aimex Co., Ltd.), add each component (other than CNT) shown in Table 4 in the types and amounts indicated. Stir with a dissolver until it becomes uniform, and then add the CNT shown in Table 4 in the types and amounts indicated and stir further. Add 1000 parts of zirconia beads with an average diameter of 0.5 mm, and while stirring at a speed of 900 rpm, use the sand mill to perform dispersion treatment for the treatment time shown in Table 4. After that, separate and remove the zirconia beads to obtain a dispersion. The absorbance ratio (A380 / A780) of the obtained dispersion is shown in Table 4. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of viscosity stability, and the results of aggregate observation are shown in Table 5.

[0231] Table 4

[0232]

[0233] Table 5

[0234]

[0235] <Preparation and Evaluation of Dispersion (Aqueous) (3)>

[0236] (Examples 25 and 26, Comparative Example 13)

[0237] In a plastic bottle (made of polyethylene) with a capacity of 200 mL, add each component (except CNT) of the types and amounts shown in Table 6. Stir with a magnetic stirrer until it becomes uniform, and then add CNT of the types and amounts shown in Table 6 and stir further. Next, use an ultrasonic homogenizer (manufactured by GINSEN CO., LTD) with a power of 300 W to perform a dispersion treatment for the treatment time shown in Table 6 to obtain a dispersion. During the dispersion treatment, stir with a magnetic stirrer while cooling with ice. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion is shown in Table 6. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of the viscosity stability, and the results of the aggregate observation are shown in Table 7.

[0238] Table 6

[0239]

[0240] Table 7

[0241]

[0242] <Preparation and Evaluation of Aqueous Dispersion (4)>

[0243] (Examples 27 - 29, 32 - 41, Reference Examples 30, 31, Comparative Examples 14 - 22)

[0244] In a plastic bottle (made of polyethylene) with a capacity of 200 mL, add each component (except CNT) of the types and amounts shown in Table 8. Stir with a magnetic stirrer until it becomes uniform, and then add CNT of the types and amounts shown in Table 8 and stir further. Next, use a high-pressure homogenizer (manufactured by Tsunehikari Co., Ltd.) equipped with a nozzle with an inner diameter of 0.3 mm to perform high-pressure treatment twice under the condition of a treatment pressure of 2 - 50 MPa. After that, use a high-pressure homogenizer (manufactured by SUGINO MACHINE LIMITED) equipped with a nozzle with an inner diameter of 0.1 mm to perform high-pressure dispersion treatment for the number of treatment times shown in Table 8 under the condition of a treatment pressure of 150 MPa to obtain a dispersion. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion is shown in Table 8. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of the viscosity stability, and the results of the aggregate observation are shown in Table 9. It should be noted that in Comparative Example 17, the amount of the dispersant relative to CNT was excessively small, or the CNT was not loosened, resulting in blockage in the chamber, so the treatment was abandoned halfway.

[0245] <Preparation and Evaluation of Aqueous Dispersion (5)>

[0246] (Example 42)

[0247] In a 200 mL plastic bottle (made of polyethylene), add the respective components (excluding CNT) of the types and amounts shown in Table 8. Stir with a magnetic stirrer until homogeneous, then add the CNT of the types and amounts shown in Table 8 and stir further. Then, process twice with a homogenizer (manufactured by SMT Co., Ltd.). Next, use a high-pressure homogenizer (manufactured by Tokuyama Co., Ltd.) equipped with a nozzle having an inner diameter of 0.3 mm and perform high-pressure treatment twice under the condition of a treatment pressure of 2 to 50 MPa. After that, use a high-pressure homogenizer (manufactured by SUGINO MACHINE LIMITED) equipped with a nozzle having an inner diameter of 0.1 mm and perform high-pressure dispersion treatment the number of treatment times shown in Table 8 under the condition of a treatment pressure of 150 MPa to obtain a dispersion. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion is shown in Table 8. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of viscosity stability, and the results of aggregate observation are shown in Table 9.

[0248] <Preparation and evaluation of aqueous dispersion (6)>

[0249] (Comparative Examples 23 and 24)

[0250] In a 200 mL plastic bottle (made of polyethylene), add the respective components (excluding CNT) of the types and amounts shown in Table 8. Stir with a magnetic stirrer until homogeneous, then add the CNT of the types and amounts shown in Table 8 and stir further. Then, use a high-shear mixer (manufactured by Silverson) and perform stirring treatment for 10 minutes at a circumferential speed of 8000 rpm. Use a high-pressure homogenizer (manufactured by SUGINO MACHINE LIMITED) equipped with a nozzle having an inner diameter of 0.1 mm and perform high-pressure dispersion treatment the number of treatment times shown in Table 8 under the condition of a treatment pressure of 150 MPa to obtain a dispersion. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion is shown in Table 8. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of viscosity stability, and the results of aggregate observation are shown in Table 9.

[0251] Table 8

[0252]

[0253] *: Number of treatment times of dispersion treatment

[0254] Table 9

[0255]

[0256] <Preparation and evaluation of aqueous dispersion (7)>

[0257] (Examples 43 to 47, Comparative Examples 25 to 29, and 32)

[0258] Set the conditions shown in Table 10. Except for this, a dispersion was obtained in the same manner as in the aforementioned Examples 27 to 41 and Comparative Examples 14 to 22. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion is shown in Table 10. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of viscosity stability, and the results of aggregate observation are shown in Table 11.

[0259] <Preparation and Evaluation of Dispersion (Aqueous) (8)>

[0260] (Comparative Examples 30 and 31)

[0261] In a 200 mL plastic bottle (made of polyethylene), the components (excluding CNT) of the types and amounts shown in Table 10 were added. After stirring until uniform, CNT of the types and amounts shown in Table 10 was added and further stirred. Then, using a high-pressure homogenizer (manufactured by Tsunehikari Co., Ltd.) equipped with a nozzle having an inner diameter of 0.3 mm, high-pressure treatment was performed twice under the condition of a treatment pressure of 2 to 50 MPa to obtain the dispersion of Comparative Example 30. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion is shown in Table 10. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of viscosity stability, and the results of aggregate observation are shown in Table 11. Furthermore, using a high-pressure homogenizer (manufactured by SUGINO MACHINE LIMITED) equipped with a nozzle having an inner diameter of 0.1 mm, high-pressure dispersion treatment was attempted for the dispersion of Comparative Example 31 under the condition of a treatment pressure of 150 MPa. However, the viscosity of the dispersion was excessively high or blockage occurred in the chamber, and the treatment was abandoned halfway.

[0262] Table 10

[0263]

[0264] *: Number of treatment times of dispersion treatment

[0265] Table 11

[0266]

[0267] <Preparation and Evaluation of Dispersion (Solvent-based) (1)>

[0268] (Examples 48 to 56, 59, 60, Reference Examples 57, 58, Comparative Examples 33 to 45)

[0269] In a plastic bottle (made of polyethylene) with a capacity of 100 mL, add the components (excluding CNT) of the types and amounts shown in Table 12. Stir with a magnetic stirrer until it becomes uniform, then add the CNT of the types and amounts shown in Table 12 and stir further. Add 200 parts of zirconia beads with an average diameter of 0.5 mm, and use SCANDEX (manufactured by SCANDEX LIMITED) to perform dispersion treatment for the treatment time shown in Table 12. After that, separate and remove the zirconia beads to obtain a dispersion. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion is shown in Table 12. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of viscosity stability, and the results of aggregate observation are shown in Table 13. The meanings of the abbreviations of the liquid media used are shown below.

[0270] ·IPA: Isopropyl alcohol

[0271] ·MEK: Methyl ethyl ketone

[0272] ·BuOAc: Butyl acetate

[0273] ·PGMAc: Propylene glycol monomethyl ether acetate

[0274] ·PGME: Propylene glycol monomethyl ether

[0275] ·NMP: N-Methyl-2-pyrrolidone

[0276] Table 12

[0277]

[0278] Table 13

[0279]

[0280] <Preparation and evaluation of dispersion (solvent system) (2)>

[0281] (Examples 61 to 69, Comparative Examples 46 to 52)

[0282] In the container of a 1 / 4G sand mill (manufactured by Aimex Co., Ltd.), add the components (excluding CNT) of the types and amounts shown in Table 14. Stir with a dissolver until it becomes uniform, then add the CNT of the types and amounts shown in Table 14 and stir further. Add 1000 parts of zirconia beads with an average diameter of 0.5 mm, and while stirring at a speed of 900 rpm, use the sand mill to perform dispersion treatment for the treatment time shown in Table 14. After that, separate and remove the zirconia beads to obtain a dispersion. The absorbance ratio (A 380 / A 780)Shown in Table 14. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of the viscosity stability, and the results of the aggregate observation are shown in Table 15.

[0283] Table 14

[0284]

[0285] Table 15

[0286]

[0287] <Preparation and Evaluation of Dispersion (Solvent System) (3)>

[0288] (Examples 70 - 75, Comparative Examples 53 - 57)

[0289] Add each component (except CNT) of the type and amount shown in Table 16 to a plastic bottle (made of polyethylene) with a capacity of 200 mL. Stir with a magnetic stirrer until it becomes uniform, then add the CNT of the type and amount shown in Table 16 and stir further. Next, use an ultrasonic homogenizer (manufactured by GINSEN CO., LTD) with a power of 300 W to perform dispersion treatment for the treatment time shown in Table 16 to obtain a dispersion. During the dispersion treatment, stir with a magnetic stirrer while cooling with ice. The absorbance ratio (A 380 / A 780 ) is shown in Table 16. In addition, the measurement results of the viscosity of the obtained dispersion, the evaluation results of the viscosity stability, and the results of the aggregate observation are shown in Table 17.

[0290] Table 16

[0291]

[0292] Table 17

[0293]

[0294] <Preparation and Evaluation of Dispersion (Solvent System) (4)>

[0295] (Examples 76 - 81, Reference Examples 82 - 85, Comparative Examples 58 - 64)

[0296] Add each component (excluding CNT) of the type and amount shown in Table 18 to a plastic bottle (made of polyethylene) with a capacity of 200 mL. Stir with a magnetic stirrer until it becomes uniform, then add CNT of the type and amount shown in Table 18 and stir further. Next, use a high-pressure homogenizer (manufactured by Tokiwa Shoten) equipped with a nozzle having an inner diameter of 0.3 mm and perform high-pressure treatment twice under the condition of a treatment pressure of 2 to 50 MPa. After that, use a high-pressure homogenizer (manufactured by SUGINO MACHINE LIMITED) equipped with a nozzle having an inner diameter of 0.1 mm and perform high-pressure dispersion treatment for the number of treatment times shown in Table 18 under the condition of a treatment pressure of 150 MPa to obtain a dispersion liquid. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion liquid is shown in Table 18. In addition, the measurement results of the viscosity of the obtained dispersion liquid, the evaluation results of viscosity stability, and the results of aggregate observation are shown in Table 19. It should be noted that in Comparative Example 64, the dispersant was not suitable for CNT, or CNT was not loosened, resulting in blockage in the chamber, so the treatment was abandoned halfway.

[0297] (Reference Example 86)

[0298] Add each component (excluding CNT) of the type and amount shown in Table 18 to a plastic bottle (made of polyethylene) with a capacity of 200 mL. Stir with a magnetic stirrer until it becomes uniform, then add CNT of the type and amount shown in Table 18, stir further, and then perform treatment twice with a homogenizer (manufactured by SMT Co., Ltd.). Next, use a high-pressure homogenizer (manufactured by Tokiwa Shoten) equipped with a nozzle having an inner diameter of 0.3 mm and perform high-pressure treatment twice under the condition of a treatment pressure of 2 to 50 MPa. After that, use a high-pressure homogenizer (manufactured by SUGINO MACHINE LIMITED) equipped with a nozzle having an inner diameter of 0.1 mm and perform high-pressure dispersion treatment for the number of treatment times shown in Table 18 under the condition of a treatment pressure of 150 MPa to obtain a dispersion liquid. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion liquid is shown in Table 18. In addition, the measurement results of the viscosity of the obtained dispersion liquid, the evaluation results of viscosity stability, and the results of aggregate observation are shown in Table 19.

[0299] Table 18

[0300]

[0301] *: Number of treatment times of dispersion treatment

[0302] Table 19

[0303]

[0304] As described above, the dispersion treatment is carried out in such a way that the absorbance ratio (A 380 / A 780 ) becomes 1.60 or more. Thus, even if the composition and the dispersion process are different, the original performance of the carbon material containing carbon nanotubes can be fully exerted, and a dispersion liquid with excellent viscosity stability and substantially no observable aggregates can be obtained.

[0305] (Application Example 1-1: Manufacturing Method at the Time of Enlargement)

[0306] Add 1000 parts of dispersant a and 8800 parts of water to a 20 L stainless steel container. Stir with a dissolver until it becomes uniform. While keeping the stirring unchanged, add 200 parts of CNT-E little by little, and then stir for 1 hour. Use a homogenizer (manufactured by SMTCo., Ltd.) to perform 4 passes of treatment in a circulation form and mix well. Then, use a high-pressure homogenizer (manufactured by Tokuyama Co., Ltd.) equipped with a nozzle having an inner diameter of 0.44 mm, and perform a time treatment equivalent to 10 passes under the condition of a treatment pressure of 2 to 50 MPa in a circulation form. After that, use a high-pressure homogenizer (manufactured by SUGINOMACHINE LIMITED) equipped with a nozzle having an inner diameter of 0.1 mm, and perform a time treatment equivalent to 5 passes in a circulation form for the high-pressure treatment under the condition of a treatment pressure of 150 MPa. The absorbance ratio (A 380 / A 780 ) of the obtained dispersion liquid becomes 1.811. In addition, the viscosity of the obtained dispersion liquid is 9.1 mPa·s, and the viscosity after 10 days is 8.8 mPa·s. The evaluation results of viscosity stability and the results of observing aggregates are both "◎".

[0307] (Application Example 2-1: Battery Material (Negative Electrode))

[0308] When manufacturing the negative electrode of a lithium ion battery, the following materials are used.

[0309] [Negative Electrode Activator]

[0310] · Graphene (FUJIFILM Wako Chemicals Corporation)

[0311] · Silicon Monoxide (FUJIFILM Wako Chemicals Corporation)

[0312] [Binder]

[0313] · 10% Aqueous Polyacrylic Acid Solution (Trade Name "CLPA-C07", FUJIFILM Wako ChemicalsCorporation)

[0314] · Carboxymethyl cellulose (trade name “CMC DAICEL 2200”, manufactured by DAICEL MIRAIZU LTD.)

[0315] Using a planetary mixer, 15 parts of silicon monoxide, 85 parts of graphene, 3 parts of the dispersion liquid manufactured in Example 37, 30 parts of a 10% aqueous solution of polyacrylic acid, and 2 parts of carboxymethyl cellulose were mixed to obtain a negative electrode material. In such a manner that the unit area weight after drying becomes 15 mg / cm 2 , using an applicator, the negative electrode material was coated on a copper foil with a thickness of 20 μm. After being placed in an oven set at 120 °C for 30 minutes to be dried, it was rolled with a roll press to obtain a negative electrode. The volume resistivity of the obtained negative electrode was 0.2 Ω·cm.

[0316] (Application Example 2-2: Battery Material (Negative Electrode))

[0317] Using the dispersion liquid manufactured in Comparative Example 21, except for this, a negative electrode was manufactured in the same manner as in the aforementioned Application Example 2-1. The volume resistivity of the manufactured negative electrode was 0.6 Ω·cm. From the above, it can be seen that by using a dispersion liquid with good dispersion evaluation, a negative electrode with a smaller volume resistivity value can be manufactured.

[0318] (Application Example 3-1: Antistatic Coating Agent)

[0319] 100 g of the dispersion liquid manufactured in Example 37, 100 g of a polymer binder (trade name “NeoPacR-9699”, manufactured by Kusumoto Chemical Co., Ltd., acrylic urethane resin), and 800 g of pure water were added to a plastic cup and stirred with a dissolver to obtain an antistatic coating agent. Using a bar coater, in such a manner that the dried coating film becomes 0.5 μm, the obtained antistatic coating agent was coated on the surface of a polyethylene terephthalate film (manufactured by Toray) with a thickness of 38 μm. After being placed in an oven set at 80 °C for 10 minutes to be dried, an antistatic coating film was obtained. The surface resistivity of the obtained film was 7×10 7 Ω / cm 2 .

[0320] (Application Example 3-2: Antistatic Coating Agent)

[0321] Using the dispersion liquid manufactured in Comparative Example 21, except for this, an antistatic coating film was manufactured in the same manner as in the aforementioned Application Example 3-1. The surface resistivity of the manufactured film was 9×10 8 Ω / cm 2 . From the above, it can be seen that by using a dispersion liquid with good dispersion evaluation, an antistatic coating film with a smaller surface resistivity value can be manufactured.

[0322] Industrial Applicability

[0323] The carbon material dispersion of the present invention is useful as a constituent material for coatings, inks, resin molded products, etc. that exhibit characteristics such as high electrical conductivity and high thermal conductivity, and is suitable for various applications such as battery materials, trays for electronic components, covers for IC chips, electromagnetic wave shields, components for automobiles, and components for robots.

Claims

1. A carbon material dispersion liquid, which contains: a carbon material including carbon nanotubes, a liquid medium, and a dispersant, wherein, the carbon material dispersion liquid does not contain volatile salts, relative to 100 parts by mass of the carbon material, the content of the dispersant in terms of solid content is 204 parts by mass or less, at any wavelength W belonging to the range of 350 to 550 nm L and any wavelength W belonging to the range of 650 to 850 nm H at the central value wavelength W M such that the absorbance is 1.8 ± 0.02, the absorbance A of the dilute dispersion obtained by diluting with a diluent containing the liquid medium at the wavelength W L is L relative to the wavelength W H the absorbance A H the ratio (A L / A H ) is 1.60 or more the dilution liquid is a blank liquid having the same composition as the carbon material dispersion liquid except that it does not contain the carbon material, The wavelength W L is 380 nm, the wavelength W H is 780 nm, and the wavelength W M is 580 nm, the liquid medium is an organic solvent, the dispersant is dispersant c or dispersant f, the trade name of dispersant c is "DYSPERBYK-9077", the trade name of dispersant f is "TEGODispers 670".

2. A carbon material dispersion liquid, which contains: a carbon material including carbon nanotubes, a liquid medium, a dispersant, and an antifoaming agent, wherein, the carbon material dispersion liquid does not contain volatile salts, relative to 100 parts by mass of the carbon material, the content of the dispersant in terms of solid content is 204 parts by mass or less, at any wavelength W belonging to the range of 350 to 550 nm L and any wavelength W belonging to the range of 650 to 850 nm H at the central value of the wavelength W M the absorbance at the wavelength W of the dilute dispersion obtained by diluting with a diluent containing the liquid medium such that the absorbance becomes 1.8 ± 0.02 L the absorbance A L with respect to the wavelength W H the absorbance A H the ratio (A L / A H ) is greater than 1.640 the dilution liquid is a blank liquid having the same composition as the carbon material dispersion liquid except that it does not contain the carbon material, The wavelength W L is 380 nm, the wavelength W H is 780 nm, and the wavelength W M is 580 nm, the liquid medium is an aqueous medium.

3. The carbon material dispersion liquid according to claim 2, wherein, the dispersant is a cellulose derivative or a polymer dispersant, the viscosity of a 1 mass% aqueous solution of the cellulose derivative is 20 to 500 mPa·s and the degree of etherification is 0.5 to 0.9, the polymer dispersant is the following polymer, the polymer contains: structural unit (1) 5 to 40 mass% derived from at least one monomer 1 selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, and their quaternary ammonium salts; structural unit (2) 50 to 80 mass% derived from monomer 2 represented by the following general formula (1); and structural unit (3) 0.5 to 40 mass% derived from monomer 3 capable of copolymerizing with monomer 1 and monomer 2, monomer 3 contains α-methylstyrene and (meth)acrylic acid, the content of the structural unit derived from α-methylstyrene is 0.5 to 5 mass%, and the content of the structural unit derived from (meth)acrylic acid is 0.5 to 30 mass%, and the number average molecular weight of the polymer is 5000 to 20000, In the general formula (1), R 1 represents a hydrogen atom or a methyl group, A represents O or NH, X represents an ethylene group or a propylene group, Y represents O, NHCOO, or NHCONH, and R 2 each independently represents a hydrogen atom or a methyl group, n represents the average number of repeating units of 20 to 100, and R 3 represents a hydrogen atom or a methyl group, wherein the number of repeating units n 2 where R is a hydrogen atom H is more than 1 / 2 of the total number of repeating units n T of the whole.

4. The carbon material dispersion liquid according to claim 3, wherein, the cellulose derivative is carboxymethyl cellulose or sodium carboxymethyl cellulose.

5. The carbon material dispersion liquid according to any one of claims 1 to 4, wherein, relative to 100 parts by mass of the carbon material, the content of the dispersant is 10 parts by mass or more, the content of the carbon material is 10 mass% or less, the content of the dispersant is 30 mass% or less.

6. Use of the carbon material dispersion liquid according to any one of claims 1 to 5 in the manufacture of any article of coating, ink, coating agent, resin molding material, conductive material, heat conductive material, and antistatic material.

7. Use of the carbon material dispersion liquid according to any one of claims 1 to 5 in the manufacture of any article of battery material and mechanical component having a coating film formed from the carbon material dispersion liquid.

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