Polymeric dispersant, polymeric dispersant composition, and carbon material dispersion

Abstract

To provide a polymeric dispersant capable of dispersing carbon material stably in a liquid medium at high concentration.SOLUTION: A polymeric dispersant for dispersing a carbon material such as carbon black in a liquid medium comprises: a structural unit (i) represented by the following general formula (1) in an amount of 45 mass% or more and 95 mass% or less (where, in the general formula (1), R1 and R3 represent a hydrogen atom or the like, R2 represents -CH2CH2- or the like, m represents any repeating number, and n represents a number from 10 to 100); a structural unit (ii) derived from a monomer that is a quaternary ammonium salt of a basic monomer such as 2-vinylpyridine in an amount of 3 mass% or more and 45 mass% or less; and a structural unit (iii) derived from a vinyl monomer copolymerizable with the structural units (i) and (ii) in an amount of 2 mass% or more and 10 mass% or less. The polymeric dispersant is a polymer having a number-average molecular weight of 10,000 or more and 30,000 or less and has UV curability.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polymer dispersant for stably dispersing a carbon material, and a carbon material dispersion obtained by using the polymer dispersant. [Background technology]

[0002] Carbon materials such as carbon black, carbon fiber, carbon nanotubes, graphite, and graphene (hereinafter simply referred to as carbon materials) have a six-membered ring graphite structure formed by covalent bonds between carbon atoms, and exhibit various properties such as electrical conductivity and thermal conductivity. Methods for utilizing these properties in a wide range of fields are being investigated. For example, focusing on the electrical properties, thermal properties, and properties as a filler of carbon materials, their use as antistatic agents, conductive materials, plastic reinforcing materials, semiconductors, fuel cell electrodes, display cathode rays, etc. is being investigated.

[0003] These applications require carbon material dispersions that have good dispersibility and maintain that dispersibility for a long period of time. However, nano-sized carbon materials have high surface energy and are prone to aggregation due to the strong van der Waals forces acting on them. Therefore, even when dispersed in a liquid medium, they often aggregate immediately.

[0004] Dispersants are generally used to stably disperse carbon materials in liquid media. For example, solvent-based dispersions of carbon nanotubes using cationic surfactants such as alkanolamine salts or polymer dispersants such as styrene-acrylic resins have been proposed (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-174084 [Patent Document 2] Special Publication No. 2013-537570 Summary of the Invention [Problem to be solved by the invention]

[0006] However, while using low-molecular-weight surfactants as dispersants makes it possible to disperse carbon materials in liquid media, the dispersibility is not always sufficient, and there are also issues such as a tendency for the carbon material to re-aggregate. Furthermore, when using general polymer dispersants, the resulting dispersion tends to exhibit thixotropic properties, which can lead to the carbon material settling or gelling over time. Furthermore, when used in UV-curable coating agents, the polymer dispersant dispersing the carbon material may not cure under UV light, resulting in a deterioration in the strength and adhesion of the coating film.

[0007] The present invention has been made in consideration of the problems of the prior art, and its object is to provide a polymeric dispersant for carbon materials that has excellent dispersibility even when the carbon material is contained at a high concentration and that stably maintains dispersibility over a long period of time. Furthermore, the present invention provides a polymeric dispersant that, when used in UV-curable coating agents or inks, has UV-curable groups in the polymeric dispersant, thereby eliminating components that are not incorporated into the coating film, and the UV-curable groups allow the polymeric dispersant to function as a crosslinker, thereby improving the durability and adhesion of the coating film obtained from the coating agent or ink. A further object is to provide a carbon material dispersion with good dispersibility obtained by using the above-mentioned polymeric dispersant. [Means for solving the problem]

[0008] That is, according to the present invention, the following polymer dispersant is provided. [1] A polymer dispersant for dispersing at least one carbon material selected from the group consisting of carbon black, carbon fiber, carbon nanotube, graphite, and graphene in a liquid medium, comprising: The polymer dispersant contains 45% by mass or more and 95% by mass or less of a structural unit (i) having a (meth)acryloyloxy group bonded to an end thereof, which is represented by the following general formula (1):

[0009] [ka]

[0010] (In the general formula (1), R 1 and R 3 represents a hydrogen atom or a methyl group, and R 2 represents -CH2CH2- or -CH2CH2OCH2CH2-, m represents an arbitrary number of repetitions, and n represents 10 to 100. A polymer dispersant having UV-curable properties, the polymer comprising: 3% by mass or more and 45% by mass or less of structural units (ii) derived from a monomer that is a quaternary ammonium salt of at least one basic monomer selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate; and 2% by mass or more and 10% by mass or less of structural units (iii) derived from a vinyl monomer copolymerizable with the structural units (i) and the structural units (ii). The polymer dispersant has a number average molecular weight of 10,000 or more and 30,000 or less.

[0011] [2] The polymer dispersant according to [1], wherein the quaternary ammonium salt of the basic monomer is a benzyl chloride salt, a naphthyl methyl chloride salt, or an anthracenyl methyl chloride salt of the basic monomer. [3] The polymer dispersant according to [1] or [2], wherein the vinyl monomer that constitutes the structural unit (iii) contains α-methylstyrene, and the content of the structural unit derived from α-methylstyrene in the polymer is 0.5% by mass or more and 5% by mass or less. [4] A polymer dispersant composition comprising the polymer dispersant according to any one of [1] to [3] and a monomer represented by the following general formula (2):

[0012] [ka]

[0013] (In the general formula (2), R 4 represents an alkyl group having 1 to 18 carbon atoms, and R 5 represents an alkylene group or branched alkylene group having 2 to 4 carbon atoms, and R 6 represents -CH2CH2- or -CH2CH2OCH2CH2-, and R 7 represents hydrogen or a methyl group, and p represents 10 to 100. [5] A carbon material dispersion comprising the polymer dispersant according to any one of [1] to [3], the carbon material, and the liquid medium. [6] The carbon material dispersion liquid according to [5], wherein the liquid medium contains at least one of an ultraviolet-curable monomer and an oligomer having one or more (meth)acryloyloxy groups. [7] The carbon material dispersion liquid according to [5] or [6], wherein the content of the polymer dispersant relative to 100 parts by mass of the carbon material is 10 parts by mass or more and 200 parts by mass or less, and the content of the carbon material relative to 100% by mass of the carbon material dispersion liquid is 15% by mass or less. [Effects of the Invention]

[0014] According to the present invention, a carbon material dispersion can be provided that exhibits excellent dispersibility even when containing a high concentration of carbon material, and that maintains stable dispersibility over a long period of time. The carbon material dispersion of the present invention exhibits excellent dispersibility, storage stability, viscosity characteristics, and processability, and can be used to form a carbon coating film by coating or the like. Furthermore, by appropriately selecting the carbon material, a highly transparent film can be formed. Furthermore, even with a low content of polymer dispersant, the carbon material is well dispersed, making it possible to form a coating film with a high carbon material content, thereby utilizing the properties of the carbon material itself, such as electrical conductivity and thermal conductivity. Furthermore, the polymer dispersant that disperses the carbon material contains ultraviolet-curable groups. When used in ultraviolet-curable coating agents, the polymer dispersant can also be cured by ultraviolet light to enhance the durability of the coating film. Additionally, since the polymer dispersant contains numerous ultraviolet-curable groups, it acts as a crosslinking agent, contributing to the durability of the coating film and adhesion to the substrate, as described above. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. <Polymer dispersant> The polymer dispersant according to this embodiment is a polymer dispersant that disperses at least one carbon material selected from the group consisting of carbon black, carbon fiber, carbon nanotubes, graphite, and graphene in a liquid medium, and the polymer dispersant has 45% by mass or more and 95% by mass or less of structural units (i) having (meth)acryloyloxy groups bonded to their terminals, which are represented by the following general formula (1):

[0016] [ka]

[0017] In the general formula (1), R 1 and R 3 represents a hydrogen atom or a methyl group, and R2 represents -CH2CH2- or -CH2CH2OCH2CH2-, m represents an arbitrary number of repetitions, and n represents 10 to 100. Furthermore, the polymer dispersant is a polymer having a number average molecular weight of 10,000 or more and 30,000 or less, and is UV-curable, and has 3% by mass or more and 45% by mass or less of structural units (ii) derived from a monomer that is a quaternary ammonium salt of at least one basic monomer selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate, and 2% by mass or more and 10% by mass or less of structural units (iii) derived from a vinyl monomer copolymerizable with the structural units (i) and the structural units (ii).

[0018] This embodiment is characterized by the above-described configuration, in which the polymer dispersant contains the structural unit (i) of general formula (1), thereby forming a graft-type polymer in which the polyalkylene glycol chain of general formula (1) is grafted to the main chain. The grafted polyalkylene glycol chain is present in a high content of 45% by mass or more and 95% by mass or less of the polymer dispersant. Furthermore, the main chain contains a vinyl-based monomer having an amino group, whose amino group has a quaternary ammonium salt in the form of an organic halide. In other words, the main chain contains a cationic group. By using the polymer dispersant according to this embodiment, carbon materials can be dispersed in a liquid medium with low viscosity and without aggregation during storage. The cationic groups of the main chain adsorb to the carbon material, and the grafted polyalkylene glycol chains cause steric repulsion between particles, allowing the carbon material to be well dispersed in the liquid medium.

[0019] Furthermore, the polymer dispersant is characterized in that the end of the grafted polyalkylene glycol chain in the polymer structure is bonded to a radically polymerizable (meth)acryloxy group. When a UV-curable monomer or oligomer is used as the liquid medium for an active energy-curable coating that can be cured with active energy such as UV or electron beams, particularly preferably a UV-curable coating, the polymer dispersant according to this embodiment reacts with the monomer or the like of the liquid medium, and the polymer dispersant itself becomes a film-forming component. Furthermore, since the polymer dispersant contains multiple (meth)acryloyloxy groups, it acts as a crosslinking agent and improves the durability or physical properties of the film.

[0020] The polymer dispersant according to this embodiment contains 45% by mass or more and 95% by mass or less of structural units (i) having (meth)acryloyloxy groups bonded to the terminals, as represented by the following general formula (1).

[0021] [ka]

[0022] In the general formula (1), R 1 and R 3 represents a hydrogen atom or a methyl group, and R 2 represents -CH2CH2- or -CH2CH2OCH2CH2-, m represents an arbitrary number of repetitions, and n represents 10 to 100. This structural unit is a structural unit that becomes a branched graft chain of the polymer that is the polymer dispersant according to this embodiment. The structure is a polypropylene glycol chain, with the repeating unit n being 10 to 100, and the molecular weight of the graft chain being in the range of 580 to 5800. If the repeating unit n is less than 10, the grafted molecular weight is small, so sufficient steric repulsion cannot be exerted, and dispersion stability of the carbon material may not be achieved. On the other hand, if the repeating unit n is greater than 100, the constituent monomer has a large molecular weight, so it may remain unpolymerized during the production of the polymer dispersant or the viscosity of the dispersion may increase. It is particularly preferable that the repeating unit n is 17 to 51, and the molecular weight of the graft chain is 1000 to 3000.

[0023] The polypropylene glycol chain has the above-mentioned structure, and its end is linked to a (meth)acryloyl group via a urethane bond, with -CH2CH2- or -CH2CHOCH2CH2- as the linking group. Because this end is a (meth)acryloyloxy group, when the polymer dispersant according to this embodiment is used in an ultraviolet-curable coating agent, the (meth)acryloyloxy group polymerizes, causing the polymer dispersant to react with the ultraviolet-curable monomer or oligomer contained in the coating agent via radical polymerization. This allows the polymer dispersant to undergo a crosslinking reaction and become a coating film component. Furthermore, the polymer dispersant contains a large number of (meth)acryloyloxy groups, which act as a crosslinking agent and contribute to the adhesion of the coating film components or durability such as abrasion resistance.

[0024] One end is bonded to the main chain as an ester group, forming a graft structure. This structural unit (i) is introduced into the polymer dispersant by the following method. That is, first, poly(n=10 to 100)propylene glycol mono(meth)acrylate is used as a monomer unit and polymerized with other monomers to form a structural component. Then, one hydroxyl group of the polypropylene glycol mono(meth)acrylate is reacted with (meth)acryloyloxyethyl isocyanate or (meth)acryloyloxyethoxyethyl isocyanate, thereby introducing this structural unit (i) into the polymer dispersant as a graft chain.

[0025] A key feature of this polymer dispersant is that the amount of raw material that constitutes this structural unit (i) is 45% by mass or more and 95% by mass or less of all raw materials. By incorporating a large amount of this structural unit, the dispersion stability of the carbon material can be improved due to steric hindrance. If this amount is less than 45% by mass, sufficient dispersion stability cannot be achieved. On the other hand, if this amount is more than 95% by mass, when an attempt is made to introduce an amount that constitutes this structural unit, the molecular weight of polypropylene glycol mono(meth)acrylate is large, resulting in poor polymerization during the production of the polymer dispersant, and the unit may remain unpolymerized. This amount is preferably 50% by mass or more and 90% by mass or less, and more preferably 51% by mass or more and 85% by mass or less. In addition, some of the structural units (i) may contain polypropylene glycol mono(meth)acrylate in which one of the hydroxyl groups has not been reacted with isocyanate. In this specification, such structural units are also included in the above amount.

[0026] Next, examples of units constituting the polymer dispersant according to this embodiment include structural unit (ii) derived from a monomer that is a quaternary ammonium salt of at least one basic monomer selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate. This structural component is a quaternary ammonium salt, and is a group that adsorbs to a carbon material composed of a six-membered aromatic carbon ring through ionic interaction with the carbon material, and further, when the counter ion is an aromatic ring, through ππ stacking.

[0027] The monomer is a quaternary ammonium salt of at least one basic monomer selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate. The counterion is a counterion of a quaternary ammonium salt in which an alkyl halide such as chlorine, bromine, or iodine, or an arylmethyl halide, forms a salt with a tertiary amino group. Specific examples include alkyl halides such as methyl chloride, methyl bromide, methyl iodide, and lauryl chloride; benzyl chloride, benzyl bromide, benzyl iodide, naphthyl methyl chloride, and anthracenyl methyl chloride. In particular, in this embodiment, a counterion having an aromatic ring is preferred to enhance the adsorption of the 6-membered aromatic ring to the carbon material. Furthermore, considering colorability and other factors, it is preferable to use at least one counterion selected from the group consisting of benzyl chloride, naphthyl methyl chloride, and anthracenyl methyl chloride.

[0028] The amount of raw material that constitutes this structural unit (ii) must be 3% by mass or more and 45% by mass or less of the total raw materials of the polymer dispersant. If this amount is less than 10% by mass, the number of adsorption groups will be small, and sufficient adsorption will not be achieved, which may result in a lack of dispersion stability. On the other hand, if this amount is more than 45% by mass, the ionic character will be too high, and when incorporated into a coating agent, it may not be soluble in the liquid medium and may not be able to be mixed with the coating agent. This amount is preferably 10% by mass or more and 42% by mass or less, and more preferably 11.5% by mass or more and 40.5% by mass or less.

[0029] The polymer dispersant according to this embodiment contains a structural unit (iii) derived from a vinyl monomer copolymerizable with the structural unit (i) and the structural unit (ii). This vinyl monomer is a monomer component used to improve the polymerizability of the structural unit (i) and the structural unit (ii) with the raw material components, to polymerize without leaving any of the structural components, or to adjust molecular weight or improve adsorption. The vinyl monomer may be a conventionally known radically polymerizable vinyl monomer, such as a styrene monomer, (meth)acrylic acid, (meth)acrylate, (meth)acrylamide monomer, or (meth)acrylonitrile. The polymer dispersant may also contain 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, or the like, which are not in the form of a quaternary ammonium salt. The presence of an amino group allows carboxyl groups on the surface of a carbon material to be adsorbed by ionic bonding.

[0030] The amount of raw material for this structural unit (iii) is the remaining amount of raw materials for structural unit (i) and structural unit (ii). In this embodiment, it must be 2% by mass or more and 10% by mass or less of all raw materials for the polymer dispersant. In particular, in this embodiment, the vinyl monomer for structural unit (iii) preferably contains α-methylstyrene from the viewpoints of molecular weight adjustment and introduction of an aromatic ring into the main chain. Furthermore, the content of structural units derived from α-methylstyrene in the polymer is preferably 0.5% by mass or more and 5% by mass or less. During polymerization, α-methylstyrene generates tertiary carbon radicals to which an aromatic group is bonded, thereby reducing polymerizability and adjusting the molecular weight to a predetermined value. Furthermore, the introduction of an aromatic ring into the main chain contributes to adsorption to carbon materials. Furthermore, if this content is less than 0.5% by mass, molecular weight adjustment is not possible. If this content is more than 5% by mass, the polymerizability may be excessively reduced, resulting in a poor polymerization yield. This content is more preferably 0.8% by mass or more and 3% by mass or less.

[0031] The polymer dispersant according to this embodiment is a polymer having a number-average molecular weight of 10,000 or more and 30,000 or less. If the number-average molecular weight is less than 10,000, the main chain of the graft structure has a small molecular weight, so even if the dispersant is adsorbed, it may be detached, resulting in poor dispersion stability. On the other hand, if the number-average molecular weight exceeds 30,000, the molecular weight may be too large, increasing the viscosity of the dispersion. The number-average molecular weight is preferably 12,000 or more and 25,000 or less. This number-average molecular weight is the number-average molecular weight in terms of polystyrene using gel perchromatography.

[0032] The polymer dispersant according to this embodiment has been described above, and its manufacturing method is not particularly limited. Preferred examples are described below, but the present invention is not limited thereto. The polymer dispersant according to this embodiment is preferably manufactured by solution polymerization. Using a polymerization solvent, the above-described polypropylene glycol mono(meth)acrylate and the monomers serving as raw materials for the structural units (ii) and (iii) are thermally polymerized using a conventionally known azo-based or peroxide-based radical polymerization initiator such as azobisisobutyronitrile or benzoyl peroxide to form a polymer. After polymerization is complete, as described above, (meth)acryloyloxyethyl isocyanate or the like is added to introduce radically polymerizable (meth)acryloyloxy groups to the ends of the polypropylene glycol chains, thereby obtaining the polymerizable polymer. Alternatively, polypropylene glycol mono(meth)acrylate, at least one basic monomer selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, dimethylaminoethyl(meth)acrylate, and diethylaminoethyl(meth)acrylate, and a monomer that serves as a raw material for structural unit (iii) may be polymerized, and then a quaternizing agent such as an alkyl halide may be added to convert the amino group of the basic monomer into a quaternary ammonium salt, followed by introducing a radically polymerizable group into the terminal.

[0033] The solvent used in this solution polymerization is a conventionally known organic solvent and is not particularly limited. Specifically, one or more solvents such as hydrocarbons, ketones, esters, glycols, glycol esters, amides, sulfoxides, carbonates, and ionic liquids can be used. While these organic solvents may be used, they are not environmentally friendly as volatile organic solvents (VOCs). Furthermore, when used in UV-curable coatings, the coatings are environmentally friendly because all of their constituent components become film components. Therefore, it is not preferable to include an organic solvent in the polymer dispersant of this embodiment. Therefore, it is preferable to use a polyglycol-based solvent, which is a nonvolatile solvent with a relatively large molecular weight and can dissolve the polymer dispersant of this embodiment (n = 4 or more), as the solvent used in the polymerization. Specific examples include polyethylene glycol monoalkyl ethers, polypropylene glycol monoalkyl ethers, polyethylene propylene glycol monoalkyl ethers, and polyethylene glycol dialkyl ethers. The use of this polyglycol-based solvent can make the coating nonvolatile.

[0034] However, although the polyglycol-based solvent is non-volatile, it cannot be incorporated into the coating film and acts plastically, which may deteriorate the physical properties of the coating film. Therefore, the polymer dispersant composition according to this embodiment is preferably a composition of the polymer dispersant according to this embodiment described above and a monomer represented by the following general formula (2):

[0035] [ka]

[0036] In the general formula (2), R 4 represents an alkyl group having 1 to 18 carbon atoms, and R 5 represents an alkylene group or branched alkylene group having 2 to 4 carbon atoms, and R 6 represents -CH2CH2- or -CH2CH2OCH2CH2-, and R 7represents hydrogen or a methyl group, and p represents 10 to 100.

[0037] The monomer represented by general formula (2) is R 5 It is a monomer having a structure in which one end of a poly(p=10-100) alkylene glycol having an ethylene, propylene, methylethylene, or tetramethylene group is an alkyl ether having a carbon number ranging from a methyl group to an octadecyl group, and the other end has a (meth)acryloyloxy group bonded via a urethane bond with -CH2CH2- or -CH2CHOCH2CH2-. This monomer has a relatively large molecular weight, is nonvolatile, and has the radically polymerizable (meth)acryloyloxy group at the end, which allows it to become a component of a coating film.

[0038] This monomer component can be obtained by using a polyalkylene glycol monoalkyl ether having 10 to 100 repeating units as a solvent when polymerizing the polymer dispersant of this embodiment, polymerizing the polymer dispersant of this embodiment, and then reacting it with (meth)acryloyloxyethyl isocyanate or the like when adding a radically polymerizable group to the end of the polymer dispersant of this embodiment. At the same time, the (meth)acryloyloxyethyl isocyanate or the like is reacted with the hydroxyl group at one end of the polyalkylene glycol monoalkyl ether used as the solvent, thereby converting the polyalkylene glycol monoalkyl ether solvent into a radically polymerizable monomer of general formula (2).

[0039] The polyalkylene glycol monoalkyl ether used has a repeating unit p of 10 to 100. If the repeating unit p is less than 10, there is a possibility that an oligomeric molecular weight that generates a flash point will be contained, while if the repeating unit p is greater than 100, the viscosity will be high and polymerization may be incomplete. The repeating unit p is preferably 15 to 50. Specific examples of this polyalkylene glycol monoalkyl ether include polyethylene glycol monomethyl ether, polypropylene glycol monomethyl ether, and polyethylene glycol polypropylene glycol monobutyl ether. Polyethylene glycol polypropylene glycol monobutyl ether is preferred, as it is liquid at room temperature and is commercially available in a wide variety of molecular weight ranges.

[0040] In the composition of the polymer dispersant and the monomer represented by general formula (2) according to this embodiment, the content of the polymer dispersant is optional and is not particularly limited, but the content of the polymer dispersant is preferably 30% by mass or more and 70% by mass or less. The reaction of the isocyanate and hydroxyl group of the polymer dispersant, polyalkylene glycol monoalkyl ether, and (meth)acryloyloxyethyl isocyanate or the like can be achieved by a conventionally known method and is not particularly limited. The reaction can be achieved by thermal reaction or by reaction using tin laurate, amine, or the like as a catalyst.

[0041] <Carbon materials> The polymeric dispersant according to this embodiment disperses at least one carbon material selected from the group consisting of carbon black, carbon fiber, carbon nanotubes, graphite, and graphene in a liquid medium. Examples of carbon materials used in this embodiment include carbon black, carbon fiber, carbon nanotubes, graphite, and graphene. The details of these materials are not particularly limited. For example, acetylene black, furnace black, thermal black, and ketjen black can be used as the carbon black. There are no particular limitations on the structure, oil absorption, specific surface area, or surface modification such as oxidation, and various conventionally known carbon blacks can be used.

[0042] Examples of carbon fibers include PAN-based carbon fibers made from polyacrylonitrile, pitch-based carbon fibers made from pitches, and recycled products thereof. In particular, so-called carbon nanofibers, which have nanometer-sized fiber diameters and are formed by rolling up a six-membered ring graphite structure into a cylindrical shape, and carbon nanotubes, which have a single-nanometer diameter, can be used. Regarding carbon nanofibers or carbon nanotubes, multi-wall or single-wall carbon nanofibers can be used.

[0043] Graphite and graphene, which are nanosheets consisting of one to several carbon layers, can be used. The above carbon materials are not limited in particle size, fiber diameter, fiber length, shape, or manufacturing method. Mixtures of these materials can also be used. The carbon materials may be doped with other metals such as platinum and palladium, or metal salts.

[0044] Furthermore, the surface of these carbon materials may be modified by oxidation, plasma treatment, radiation treatment, corona treatment, coupling treatment, or the like.

[0045] <Carbon material dispersion> This embodiment is characterized by a carbon material dispersion (hereinafter also referred to simply as dispersion) containing the above-described carbon material, liquid medium, and polymer dispersant, wherein the polymer dispersant is the polymer dispersant according to this embodiment. As the liquid medium, a conventionally known organic solvent as described above can be used. Particularly preferably, the liquid medium used in this embodiment is one that can be used to form an ultraviolet-curable coating agent using the carbon material dispersion according to this embodiment, and the liquid medium is preferably a mixed liquid containing at least one of ultraviolet-curable monomers and oligomers having one or more (meth)acryloyloxy groups.

[0046] The mixed liquid containing at least one of the ultraviolet curable monomer and oligomer may be any conventionally known material, and is not particularly limited. Specific examples include curable components such as monofunctional monomers, polyfunctional monomers, photocurable oligomers, and photocurable polymers. More specifically, examples of the monofunctional monomer include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, adamantyl (meth)acrylate, adamantylmethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, ) acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polyethylene glycol monomethyl ether (meth)acrylate, 2-ethoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, allyl (meth)acrylate, vinyloxyethoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, an adduct of phthalic anhydride and 2-hydroxyethyl (meth)acrylate, and acryloylmorpholine, and other radical polymerizable monomers are also included.

[0047] Examples of polyfunctional monomers or photocurable oligomers include neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, poly(n=2 or more) ethylene glycol di(meth)acrylate, polypropylene glycol (n=2 or more) di(meth)acrylate, polybutylene glycol (n=2 or more) di(meth)acrylate, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, trimethylolpropane diacrylate, bis(2-(meth)acryloxyethy (meth)-hydroxyethyl-isocyanurate, trimethylolpropane tri(meth)acrylate, tris(2-(meth)acryloxyethyl)isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy poly(meth)acrylates such as epoxy di(meth)acrylates obtained by reacting bisphenol A diepoxy with (meth)acrylic acid, 1,Urethane tri(meth)acrylate obtained by reacting 2-hydroxyethyl (meth)acrylate with a trimer of 6-hexamethylene diisocyanate, urethane di(meth)acrylate obtained by reacting isophorone diisocyanate with 2-hydroxypropyl (meth)acrylate, urethane hexa(meth)acrylate obtained by reacting isophorone diisocyanate with pentaerythritol tri(meth)acrylate, urethane di(meth)acrylate obtained by reacting dicyclohexyl diisocyanate with 2-hydroxyethyl (meth)acrylate, dicyclo Examples of such poly(meth)acrylates include urethane poly(meth)acrylates such as urethane di(meth)acrylates obtained by reacting a urethane reaction product of hexyl diisocyanate and poly(n=6-15)tetramethylene glycol with 2-hydroxyethyl (meth)acrylate, polyester (meth)acrylates obtained by reacting trimethylolethane with succinic acid and (meth)acrylic acid, and polyester poly(meth)acrylates such as polyester (meth)acrylates obtained by reacting trimethylolpropane with succinic acid, ethylene glycol, and (meth)acrylic acid.

[0048] The photocurable polymer is a polymer such as poly(meth)acrylate, polyurethane, polyester, polyamide, polyimide, or polyepoxy resin, which has a plurality of radically polymerizable (meth)acryloyloxy groups at its terminals or side chains, and the monomer species of the polymer, the resulting polymer, and the photocurable polymer obtained by imparting photopolymerizability to the polymer are not particularly limited. Furthermore, photocurable polymers that have alkali developability due to the presence of a carboxyl group or the like can also be used.

[0049] The above is the configuration of the carbon material dispersion liquid according to this embodiment. Preferably, the mass ratio of the carbon material to the polymer dispersant according to this embodiment is 10 to 200 parts by mass per 100 parts by mass of the carbon material, and the carbon material content in the carbon material dispersion liquid is 15% by mass or less. If the amount of polymer dispersant is too small relative to the carbon material, sufficient dispersion performance tends to be difficult to achieve. On the other hand, if the amount of polymer dispersant is too large relative to the carbon material, the dispersion may become thicker, and the proportion of carbon material in the solid content tends to be relatively low. Therefore, the mass ratio of the polymer dispersant relative to 100 parts by mass of the carbon material in the carbon material dispersion liquid according to this embodiment is preferably 10 to 200 parts by mass, more preferably 20 to 150 parts by mass, and particularly preferably 30 to 100 parts by mass. The carbon material content in the carbon material dispersion liquid is preferably 15% by mass or less, more preferably 0.01 to 10% by mass. By using the polymer dispersant according to this embodiment, and more preferably by blending the carbon material and the polymer dispersant in the above-mentioned mass ratio, a more stably dispersed carbon material dispersion can be obtained.

[0050] The carbon material dispersion liquid according to this embodiment may contain other components in addition to the carbon material, polymer dispersant, and liquid medium described above. Specifically, the carbon material dispersion liquid may contain a photopolymerization initiator, a light stabilizer, an antioxidant, a dye, a pigment, a fluorescent brightening agent, a leveling agent, an antifoaming agent, a lubricant, a thickener, an antistatic agent, a surfactant, a silane coupling agent, an anti-yellowing agent, a bluing agent, an infrared absorber, an adhesion promoter, an antifouling agent, a water repellent agent, a curing catalyst, an inorganic filler such as silica, and metal fine particles.

[0051] Among them, photopolymerization initiators include carbonyl compounds such as benzoin, benzoin monomethyl ether, benzoin isopropyl ether, acetoin, benzil, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, benzil dimethyl ketal, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, methylphenyl glyoxylate, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; Examples include phosphate compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; as well as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1 and camphorquinone, and the selected compound is selected depending on the wavelength of the curing light, and in some cases, multiple compounds may be used.

[0052] The above are the main components of the carbon material dispersion liquid according to this embodiment, and the composition of each component is determined depending on the intended use, so the other components are not limited in the present invention. Conventionally known compositions and materials can be used. As other additives, conventionally known ones can be used and are not particularly limited. Specifically, photopolymerization initiators for photocuring, organic solvents for adjusting the viscosity and applicability of the coating material, etc. are used and are not limited thereto.

[0053] The physical properties of the carbon material dispersion according to this embodiment are conventionally known and are not particularly limited. From a practical standpoint, the viscosity of the carbon material dispersion is preferably 3 mPa·s or more and 100 mPa·s or less.

[0054] The method for dispersing the carbon material using the polymer dispersant described above when preparing the carbon material dispersion liquid according to this embodiment is not limited, and can be carried out by any conventionally known method. For example, dispersion methods such as dispersion using a disperser, kneading with a three-roll mill, ultrasonic dispersion, bead mill dispersion, an emulsifier, or a high-pressure homogenizer can be used. Among these, bead mill dispersion, ultrasonic dispersion, or a high-pressure homogenizer are preferred because of their high dispersion effect. The carbon material dispersion liquid according to this embodiment can be easily prepared by mixing at least the carbon material, the liquid medium, and the polymer dispersant, and then performing a dispersion treatment.

[0055] The dispersibility of the carbon material in the carbon material dispersion according to this embodiment can be confirmed by measuring the absorbance of the dispersion using a spectrophotometer, as described below. First, several samples of dispersions containing a known, extremely low concentration of carbon material are prepared, and the absorbance at a specific wavelength is measured to create a calibration curve of absorbance versus concentration. Next, the carbon material, liquid medium, and polymer dispersant are mixed and dispersed using a predetermined dispersion method. After centrifugation, the remaining carbon material is allowed to settle and separate. The supernatant is diluted to a concentration at which absorbance can be measured, and the absorbance is measured. The concentration is calculated from the calibration curve. Dispersibility can be evaluated by comparing the concentration of the resulting dispersion with the amount of the dispersion. Alternatively, the carbon material dispersion after centrifugation can be left standing for an extended period of time to check for the presence or absence of aggregates. Alternatively, the dispersion can be dropped onto a glass plate or the like and its condition can be confirmed using an electron microscope or the like. Alternatively, the dispersion can be coated to form a film and its electrical conductivity measured. A satisfactory dispersion can be determined when a predetermined conductivity is reached.

[0056] The carbon material dispersion according to this embodiment can be used in applications such as paints, inks, or plastics in which a carbon material is dispersed, and is expected to be used as an electrically conductive material or a thermally conductive agent, as well as an antistatic material. A paint or ink in which a carbon material is dispersed can be produced by adding a solvent, a resin, an additive, or the like to the carbon material dispersion according to this embodiment to form a paint or ink composition, or by adding the carbon material dispersion to a commercially available paint or ink. [Example]

[0057] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified. <Synthesis of polymer dispersant (polymer)>

[0058] (Synthesis Example 1) a) Polymerization A reactor equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube was charged with 71.0 parts (0.0400 mol) of polypropylene glycol polyethylene glycol monobutyl ether (trade name "Unilube 50MB-26", manufactured by NOF Corporation, molecular weight: 1776, repeating units: propylene glycol 17, ethylene glycol 17; hereinafter abbreviated as 50MB-26), 70 parts (0.0342 mol) of one-terminated methacryloyloxy polypropylene glycol (trade name "Blemmer PP-2000D", manufactured by NOF Corporation, molecular weight: 2048, repeating units: approximately 33.8; hereinafter abbreviated as PP2000D), 1.2 parts of α-methylstyrene (hereinafter abbreviated as αMS), 9.4 parts of styrene (hereinafter abbreviated as St), and 19.4 parts of 4-vinylpyridine (hereinafter abbreviated as 4VP), and the mixture was heated to 75°C while bubbling nitrogen gas. When the temperature reached 70°C, 4.5 parts of 2,2'-azobis(isobutyrate)dimethyl ester (trade name "V-601", manufactured by Wako Pure Chemical Industries, Ltd., hereinafter abbreviated as V601) was added as a polymerization initiator, and polymerization was continued at 75°C for 4 hours. An additional 2.0 parts of V601 was added, and polymerization was continued at 75°C for 4 hours to obtain a polymer solution. A sample was taken, and the molecular weight of the resulting polymer was measured by gel permeation chromatography using polystyrene standards and tetrahydrofuran as the eluent. The number average molecular weight (hereinafter abbreviated as Mn) was 22,100, the molecular weight distribution (weight average molecular weight / number average molecular weight, hereinafter abbreviated as PDI) was 1.85, and the peak top molecular weight (hereinafter abbreviated as PT) was 38,400, with almost no peaks attributable to the raw material PP2000D. The molecular weight was measured in the same manner.

[0059] b) Introduction of unsaturated groups Next, 11.5 parts (0.0742 mol, total moles of 50MB-26 and PP2000D) of 2-isocyanatoethyl methacrylate (trade name "Karends MOI", manufactured by Showa Denko K.K., molecular weight: 155.15, hereinafter abbreviated as MOI) and 0.3 parts of tin dioctanoate (hereinafter abbreviated as DOS) as a catalyst were added to the polymer solution obtained above, and the reaction was carried out at 80°C for 5 hours. When a sample was taken and measured using an infrared spectrophotometer, the peak derived from the isocyanate group disappeared, confirming the completion of the reaction. Thus, a polymer solution was obtained in which unsaturated groups were introduced into the polymer terminals and the terminals of 50MB-26.

[0060] c) Quaternary chloride Furthermore, 31.0 parts of 1-chloromethylnaphthalene (hereinafter abbreviated as CMN) and 137.5 parts of 50MB-26 were added to the unsaturated group-introduced polymer solution obtained above, and the reaction was carried out at 90°C for 5 hours. The amine value of the sample was measured and found to be 0.5 mg KOH / g (value as polymer solution), confirming that the quaternary salt formation had proceeded almost exactly as expected. The amine value was measured and calculated using a 0.1 N 2-propanol hydrochloric acid solution with an automatic potentiometric titrator. The amine value was calculated in the same manner below. The molecular weight of the obtained polymer was measured and found to be Mn 23,500, PDI 1.92, and PT 39,400. The obtained polymer solution containing the polymeric dispersant of the present invention is referred to as VG-1. The theoretical solids content of the polymeric dispersant, calculated from its blend ratio in the polymer, is 40.0%. The theoretical solid content was calculated by dividing the solid content of the components excluding the solvent 50MB-26 and the reaction product of 50MB-26 and MOI by the total amount.

[0061] (Synthesis Examples 2 to 5) Polymer solutions containing the polymer dispersant of the present invention were obtained in the same manner as in the above-mentioned Synthesis Example 1, except that the compositions were as shown in Table 1. The physical properties of the obtained polymer solutions VG-2 to VG-5 are shown in Table 1.

[0062] The meanings of the abbreviations in Table 1 are as follows: AP1000D: One-terminated methacryloyloxy polypropylene glycol (product name "Blenmar AP-1000D", NOF Corporation, molecular weight: 1060, repeating units: approximately 17) 2VP: 2-vinylpyridine VI: 1-vinylimidazole DMAEMA: 2-N,N-dimethylaminoethyl methacrylate MMA: Methyl methacrylate AOI: 2-isocyanatoethyl acrylate (trade name "Karends AOI", manufactured by Showa Denko K.K., molecular weight: 155.15 BzCl: Benzyl chloride CMA: 9-chloromethylanthracene

[0063] [Table 1]

[0064] (Comparative Synthesis Example 1) Polymer dispersant containing no unsaturated groups A reactor similar to that used in Synthesis Example 1, equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube, was charged with 71.0 parts (0.0400 mol) of 50MB-26, 70 parts (0.0342 mol) of PP-2000D, 1.2 parts of αMS, 9.4 parts of St, and 19.4 parts of 4VP. The mixture was heated to 75°C while bubbling nitrogen gas. Upon reaching 70°C, 4.5 parts of V601 were added as a polymerization initiator, and polymerization was continued at 75°C for 4 hours. An additional 2.0 parts of V601 was added, and polymerization was continued at 75°C for 4 hours to obtain a polymer solution. A sample was taken and the molecular weight of the resulting polymer was measured. The number average molecular weight (Mn) was 21,600, the PDI was 1.84, and the PT was 37,200. Almost no peaks attributable to the PP2000D used as the raw material were observed.

[0065] c) Quaternary ammonium chloride Next, 31.0 parts of CMN and 135.3 parts of 50MB-26 were added to the polymer solution obtained above, and the reaction was carried out at 90°C for 5 hours. The amine value of the sample was measured and found to be 0.6 mg KOH / g (value as polymer solution), confirming that the quaternary ammonium salt conversion had progressed almost exactly as expected. The resulting polymer solution containing the polymer dispersant is designated HVG-1. The theoretical solids content of the polymer dispersant, calculated from its blend ratio in the polymer, is 40.0%.

[0066] (Comparative Synthesis Example 2) · Polymer dispersant that does not contain quaternary ammonium salts A reactor similar to that used in Synthesis Example 1, equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube, was charged with 71.0 parts (0.0400 mol) of 50MB-26, 70 parts (0.0342 mol) of PP2000D, 1.2 parts of αMS, 9.4 parts of St, and 19.4 parts of 4VP. The mixture was heated to 75°C while bubbling with nitrogen gas. Upon reaching 70°C, 4.5 parts of V601 were added as a polymerization initiator, and polymerization was continued for 4 hours at 75°C. An additional 2.0 parts of V601 was added, and polymerization continued for 4 hours at 75°C to obtain a polymer solution. A sample was taken and the molecular weight of the resulting polymer was measured. The number average molecular weight (Mn) was 23,400, the PDI was 1.92, and the PT was 36,800. Almost no peaks attributable to the PP2000D used as the raw material were observed.

[0067] b) Introduction of unsaturated groups Next, 11.5 parts of MOI (0.0742 mol, the total number of moles of 50MB-26 and PP2000D) and 0.3 parts of DOS as a catalyst were added to the polymer solution obtained above, and the reaction was carried out at 80°C for 5 hours. A sample was taken and measured using an infrared spectrophotometer, confirming that the peaks derived from isocyanate groups had disappeared. Thus, a polymer solution was obtained in which unsaturated groups had been introduced into the polymer terminals and the terminals of 50MB-26. The resulting polymer solution containing the polymer dispersant is designated HVG-2. The theoretical solids content of the polymer dispersant, calculated from the blend ratio in this polymer, is 62.5%.

[0068] (Comparative Synthesis Example 3) A polymer dispersant containing less than 45 parts of the general formula (1) and more than 45 parts of a quaternary ammonium salt. A reactor similar to that used in Synthesis Example 1, equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube, was charged with 71.0 parts (0.0400 mol) of 50MB-26, 50 parts (0.0472 mol) of AP1000D, 1.2 parts of αMS, 15.9 parts of St, and 32.9 parts of 4VP. The mixture was heated to 75°C while bubbling with nitrogen gas. Upon reaching 70°C, 4.5 parts of V601 were added as a polymerization initiator, and polymerization was continued for 4 hours at 75°C. An additional 2.0 parts of V601 was added, and polymerization was continued for 4 hours at 75°C to obtain a polymer solution. A sample was taken and the molecular weight of the resulting polymer was measured. The number average molecular weight (Mn) was 12,600, the PDI was 1.83, and the PT was 25,100. Almost no peaks attributable to AP1000D, the starting material, were observed. The molecular weight was measured in the same manner as described below.

[0069] b) Introduction of unsaturated groups Next, 16.5 parts of MOI (0.1063 mol, the total number of moles of 50MB-26 and PP2000D) and 0.3 parts of DOS as a catalyst were added to the polymer solution obtained above, and the reaction was carried out at 80°C for 5 hours. When a sample was taken and measured using an infrared spectrophotometer, it was confirmed that the peak derived from the isocyanate group had disappeared. Therefore, a polymer solution in which unsaturated groups had been introduced into the polymer terminals and the terminals of 50MB-26 was obtained.

[0070] c) Quaternary ammonium chloride Next, 31.0 parts of CMN and 150.4 parts of 50MB-26 were added to the polymer solution obtained above, and the reaction was carried out at 90°C for 5 hours. The amine value of the sample was measured and found to be 0.5 mg KOH / g (value as polymer solution), confirming that the quaternary salt conversion had proceeded almost exactly as expected. The resulting polymer solution containing the polymer dispersant is designated HVG-3. The theoretical solids content of the polymer dispersant, calculated from its blend ratio in the polymer, is 40.0%.

[0071] Table 2 shows the compositions and physical properties of polymer solutions HVG-1 to HVG-3 containing the polymer dispersants obtained in Comparative Synthesis Examples 1 to 3.

[0072] [Table 2]

[0073] <Preparation of carbon nanotube (CNT) dispersion> Example 1 A resin container was charged with 0.2 parts of single-walled carbon nanotubes (Tuball; manufactured by OCSiAl; average diameter: 1.2-2.0 nm, average length: 2-20 μm), 99.3 parts of methyl ethyl ketone (hereinafter abbreviated as MEK), 0.50 parts of polymer solution VG-1 (theoretical solids content: 40.0%) containing a polymer dispersant, and 180 parts of zirconia beads (diameter: 0.8 mm). The CNTs were wetted but sunk to the bottom of the container, with a transparent layer on top. After 60 minutes of dispersion using a Scandex, the liquid turned uniformly black, indicating that the CNTs had disaggregated. The mixture was then centrifuged to separate any insufficiently dispersed CNTs, and the supernatant was collected as CNT dispersion liquid-1.

[0074] (Examples 2 to 12 and Comparative Examples 1 to 6) CNT dispersions-2 to-22 were prepared in the same manner as in Example 1, except for using the formulations shown in Table 3. The meanings of the abbreviations in Table 3 are as follows. MWCNT: (Hamamatsu Carbonix, multi-walled carbon nanotubes, average diameter: 10-40 nm, average length: 500 μm-1,500 μm) SG101: (Product name "SG-101", manufactured by Zeon Corporation, single-walled carbon nanotubes, average diameter: 3-5 nm, average length: 100-600 μm) 100T: (Product name "K-nanos100T", manufactured by Kumho Co., Ltd., average diameter: 11-13 nm, average length: 40-50 μm)

[0075] [Table 3]

[0076] <Calculation of Average Diameter and Average Length of CNTs> The powder of CNTs was observed with an electron microscope, and the average diameter and average length were calculated for 10 randomly selected ones. This operation was carried out in 5 batches, and the numerical ranges for the average diameter and average length were determined.

[0077] <Evaluation of CNT Dispersion Liquid> An E-type viscometer (measurement conditions: 25°C, rotor rotation speed 100 rpm) was used to measure the viscosity at 25°C of the CNT dispersion liquid immediately after dispersion (initial) and after standing for 10 days. Then, the change rate of viscosity after standing for 10 days (viscosity change rate (%)) based on the initial viscosity was calculated, and the viscosity stability of the CNT dispersion liquid was evaluated according to the following evaluation criteria. Furthermore, the state of the CNT dispersion liquid after standing for 10 days was observed by optical microscope observation (200 times), and the presence or absence of aggregates was confirmed. ◎: The viscosity change rate was less than 5%. 〇: The viscosity change rate was 5% or more and less than 10%. ×: The viscosity change rate was 10% or more.

[0078] Also, the CNT concentration of the CNT dispersion liquid after centrifugation was measured. A spectrophotometer was used for the measurement of CNT concentration. Specifically, the absorbance of a sample with a known CNT concentration was measured to create a calibration curve. Then, the absorbance of the sample diluted to a measurable concentration was measured, and the CNT concentration of the sample was calculated from the calibration curve. The ratio (%) of the CNT concentration after centrifugation to the designed CNT concentration was calculated as "dispersion stability (%)". The closer the dispersion stability is to 100%, the better the dispersion of CNTs. The evaluation results of the CNT dispersion liquid are shown in Table 4.

[0079]

Table 4

[0080] The CNT dispersion liquids dispersed using the polymer solution containing the polymer dispersant of the present invention all had excellent viscosity stability and dispersion stability, and no aggregates were observed after standing for 10 days. On the other hand, the CNT dispersion liquids of Comparative Examples 2, 3, 5, and 6 used a polymer dispersant that does not contain a quaternary ammonium salt, or the ratio of the macromonomer deviated from the present invention, so the viscosity stability and dispersion stability were poor, and aggregates were also confirmed. However, in Comparative Examples 1 and 4, a polymer dispersant having no unsaturated group was used in the polymer. Perhaps because the presence or absence of the unsaturated group did not adversely affect the dispersibility, both had good viscosity stability and dispersion stability, and no aggregates were confirmed.

[0081] <Preparation of Carbon Black (CB) Dispersion Liquid> (Example 13) Carbon black (trade name "Li-435", manufactured by Denka Co., Ltd., acetylene black) (CB) 3.0 parts, MEK 89.5 parts, VG-1 (theoretical solid content 40.0%) 7.50 parts, and zirconia beads (diameter 0.8 mmφ) 180 parts were placed in a resin container. The CB was wet but sank to the bottom of the container, and there was a transparent layer on the top. When dispersion treatment was performed for 60 minutes using a scandex, the liquid became uniformly black, and the aggregated state of the CB was resolved. Next, centrifugation was performed to sediment and separate the CB that was not sufficiently dispersed, and the supernatant was taken out as CB dispersion liquid -1.

[0082] (Examples 14 to 17, and Comparative Examples 7 and 8) CB dispersion liquids -2 to CB dispersion liquids -7 were prepared in the same manner as in Example 13 described above, except that the formulations shown in Table 5 were used.

[0083]

Table 5

[0084] <Evaluation of CB Dispersion Liquid> <00003Using an E-type viscometer (measurement conditions: 25°C, rotor rotation speed 100 rpm), the viscosity of the CB dispersion was measured at 25°C immediately after dispersion (initial) and after standing for 10 days. The rate of change in viscosity after standing for 10 days (viscosity change rate (%)) based on the initial viscosity was calculated, and the viscosity stability of the CB dispersion was evaluated according to the following evaluation criteria. ⊚: The viscosity change rate was less than 5%. Good: The viscosity change rate was 5% or more and less than 10%. ×: The viscosity change rate was 10% or more.

[0085] Furthermore, the state of the CB dispersion after standing for 10 days was observed under an optical microscope (200x magnification) to confirm the presence or absence of aggregates. The evaluation results of the CB dispersion are shown in Table 6.

[0086] [Table 6]

[0087] All of the CB dispersions dispersed using the polymer solution containing the polymer dispersant of the present invention had excellent viscosity stability, and no aggregates were observed after being left standing for 10 days. On the other hand, the CB dispersion of Comparative Example 8 had poor viscosity stability and aggregates were also observed because the macromonomer ratio was outside the scope of the present invention. However, in Comparative Example 7, a polymer dispersant that does not have unsaturated groups in the polymer was used, and in this case, the viscosity stability was good and no agglomerates were observed, probably because the presence or absence of unsaturated groups does not adversely affect dispersibility.

[0088] <Production of Coating Composition> (Production Example 1) 50 parts of the CNT dispersion liquid-1 obtained in Example 1 was diluted with 100 parts of tripropylene glycol diacrylate (hereinafter abbreviated as TPGDA), and 4 parts of a photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, trade name "Omnirad 184", manufactured by IGM Resins) was added and mixed until homogeneous, to obtain coating composition-1.

[0089] (Production Examples 2 to 17 and Comparative Production Examples 1 to 3) Coating composition-2 to coating composition-20 were obtained in the same manner as in Production Example 1 above, except that the compositions shown in Table 7 were used.

[0090] [Table 7]

[0091] <Production of cured film> (Application example 1) Coating composition 1 was applied to the treated surface of an easily adhesive PET film (Toyobo: A4160) at a dry film thickness of 14 g / m 2 The coating was applied with a D bar #14 so that the coating thickness was 100°C and dried for 40 seconds using a dryer. Next, a cured film was obtained by irradiating UV light using an 80W / cm high-pressure mercury lamp at 5m / min and one pass.

[0092] (Application Examples 2 to 17, and Comparative Application Examples 1 to 3) Cured films were obtained in the same manner as in Application Example 1, except that Coating Compositions 2 to 20 were used instead of Coating Composition 1 in Application Example 1.

[0093] <Evaluation> (Sliding property test) Using a Gakushin-type fastness tester (manufactured by Yasuda Seiki Co., Ltd.), a 1cm x 1cm flat friction plate with a No. 3 gold foil attached was used to conduct a sliding test under the conditions of a 500g load and 60 strokes per minute. After rubbing, the film surface was visually observed and rated on a 5-point scale (1 poor to 5 excellent).

[0094] (Anti-blocking test) The resulting cured film was cut into a piece measuring 4 cm x 4 cm, and placed on the untreated side of a piece of PET film cut to the same size. The piece was then subjected to a blocking test with a pressure of 4 kg / cm 2 The test was carried out for 24 hours in an atmosphere of 40°C under a load of 1000 kJ / s. After the test, the performance was evaluated according to the following evaluation criteria. The results of the sliding property test and anti-blocking property test are shown in Table 8. ◯: The cured film was easily peeled off without applying any force. △: There was a slight delay before the cured film peeled off, but the interface was not wetted. ×: The cured film did not peel off, and the interface was wet.

[0095] [Table 8]

[0096] It was found that Application Examples 1 to 17, which were prepared using a polymer solution containing the pigment dispersant of the present invention, had excellent curability, a sliding property test score of 4 or more, and good anti-blocking property test scores. On the other hand, in Comparative Application Examples 1 to 3, since the pigment dispersant does not contain an unsaturated group, the curability is poor, the sliding property test score is 2 or less, and the anti-blocking property test score is also poor. [Industrial Applicability]

[0097] The carbon material dispersion of the present invention exhibits high stability and high dispersibility, and aqueous paints, inks, plastic moldings, and the like obtained from the carbon dispersion can fully exhibit the properties of the carbon material, such as high electrical conductivity or high heat conductivity, and are suitable for various uses of the carbon material, such as battery materials, electronic component trays, IC chip covers, electromagnetic wave shields, automotive parts, and robot parts.

Claims

1. A polymer dispersant for dispersing at least one carbon material selected from the group consisting of carbon black, carbon fiber, carbon nanotube, graphite, and graphene in a liquid medium, comprising: The polymer dispersant contains 45% by mass or more and 95% by mass or less of a structural unit (i) having a (meth)acryloyloxy group bonded to an end thereof, which is represented by the following general formula (1): 【Chemical 1】 (In the general formula (1), R １ and R ３ represents a hydrogen atom or a methyl group, and R ２ Ha-CH ２ CH ２ - or -CH ２ CH ２ OCH ２ CH ２ -, m represents an arbitrary number of repetitions, and n represents 10 to 100. A polymer dispersant having ultraviolet curing properties, the polymer comprising: 3% by mass or more and 45% by mass or less of structural units (ii) derived from a monomer that is a quaternary ammonium salt of at least one basic monomer selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate; and 2% by mass or more and 10% by mass or less of structural units (iii) derived from a vinyl monomer copolymerizable with the structural units (i) and the structural units (ii). The polymer dispersant is a polymer having a number average molecular weight of 10,000 or more and 30,000 or less.

2. 2. The polymeric dispersant according to claim 1, wherein the quaternary ammonium salt of the basic monomer is a benzyl chloride salt, a naphthyl methyl chloride salt, or an anthracenyl methyl chloride salt of the basic monomer.

3. 2. The polymer dispersant according to claim 1, wherein the vinyl monomer that constitutes the structural unit (iii) contains α-methylstyrene, and the content of the structural unit derived from α-methylstyrene in the polymer is 0.5% by mass or more and 5% by mass or less.

4. A polymer dispersant composition comprising the polymer dispersant according to any one of claims 1 to 3 and a monomer represented by the following general formula (2): 【Chemistry 2】 (In the general formula (2), R ４ represents an alkyl group having 1 to 18 carbon atoms, and R ５ represents an alkylene group or branched alkylene group having 2 to 4 carbon atoms, and R ６ Ha-CH ２ CH ２ - or -CH ２ CH ２ OCH ２ CH ２ - indicates R ７ represents hydrogen or a methyl group, and p represents 10 to 100.

5. A carbon material dispersion comprising the polymer dispersant according to any one of claims 1 to 3, the carbon material, and the liquid medium.

6. The carbon material dispersion liquid according to claim 5 , wherein the liquid medium contains at least one of an ultraviolet-curable monomer and an oligomer having one or more (meth)acryloyloxy groups.

7. 6. The carbon material dispersion according to claim 5, wherein a content of the polymer dispersant relative to 100 parts by mass of the carbon material is 10 parts by mass or more and 200 parts by mass or less, and a content of the carbon material relative to 100% by mass of the carbon material dispersion is 15% by mass or less.

Images