Carbon dispersion

Abstract

The present invention provides a carbon dispersion liquid that is useful as a material for forming conductive coating films, which has low viscosity even when containing high concentrations of conductive carbon black, in which the conductive carbon black is finely dispersed in an organic solvent in a good state, and in which the good dispersion state can be maintained over a long period of time. [Solution] This is a carbon dispersion liquid used to form a conductive coating film. It contains conductive carbon black, an organic solvent, a polymeric dispersant, and a phthalocyanine compound, wherein the polymeric dispersant is a polymer having a constituent unit (A) derived from a macromonomer (A) in which a (meth)acryloyloxy group is bonded to one end of a polyalkylene glycol monomethyl ether chain via a urea bond, a constituent unit (B) derived from an aromatic vinyl monomer (B), and a constituent unit (C) derived from a nitrogen-containing monomer (C), and the phthalocyanine compound is sulfonated copper phthalocyanine.

Description

Technical Field

[0001] The present invention relates to a carbon dispersion.

Background Art

[0002] Carbon black is a black pigment composed almost entirely of carbon and is used in various applications such as black coloring. There is also carbon black with conductivity and thermal conductivity imparted by a chain-like particle connection structure and a graphite structure. By blending conductive carbon black (electrically conductive carbon black), conductivity can be imparted to an article. Therefore, electrically conductive carbon black is utilized as a material for manufacturing antistatic trays, conductive paints, conductive adhesives, battery materials, display materials, and the like.

[0003] However, since electrically conductive carbon black such as acetylene black is a nano-sized substance, it has a high surface energy and has a developed chain-like particle connection structure and a complex structure highly graphitized. In addition, since there are few functional groups present on the particle surface of carbon black, it is difficult to finely disperse it into nano-size. Furthermore, it is also difficult to maintain a finely dispersed state in nano-size, and there is a tendency for the viscosity to increase. To solve such problems, various dispersions in which carbon materials such as carbon black are dispersed in a liquid medium have been proposed (Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The dispersions proposed in Patent Documents 1-3 contained conductive carbon black dispersed in an organic solvent in a reasonably good state. However, when conductive carbon black was contained and dispersed at high concentrations, the dispersibility tended to be insufficient, and the dispersed conductive carbon black tended to re-aggregate over time, presenting a challenge that allowed for further improvement.

[0006] This invention has been made in view of the problems of the prior art, and its objective is to provide a carbon dispersion liquid that is useful as a material for forming a conductive coating film, which has low viscosity even when it contains a high concentration of conductive carbon black, in which the conductive carbon black is finely dispersed in an organic solvent in a good state, and in which the good dispersion state can be maintained for a long period of time. [Means for solving the problem]

[0007] In other words, the present invention provides the following carbon dispersion. [1] A carbon dispersion used to form a conductive coating film, comprising conductive carbon black, an organic solvent, a polymeric dispersant for dispersing the conductive carbon black in the organic solvent, and a phthalocyanine compound, wherein the polymeric dispersant comprises a structural unit (A) derived from a macromonomer (A) having a polyalkylene glycol monomethyl ether chain with 2-3 C1 alkylene groups, to which a (meth)acryloyloxy group is bonded via a urea bond to one end; a structural unit (B) derived from at least one aromatic vinyl monomer (B) selected from the group consisting of styrene, α-methylstyrene, vinylnaphthalene, vinyltoluene, and acenaphthylene; and at least one nitrogen-containing monomer selected from the group consisting of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, vinylpyridine, and quaternary ammonium salts thereof. A polymer having a constituent unit (C) derived from (C), wherein the number average molecular weight (Mn1) of the macromonomer (A) in polystyrene terms, as measured by gel permeation chromatography, is 500 to 5,000, the molecular weight distribution (weight average molecular weight / number average molecular weight) is 1.5 or less, the total content of the constituent unit (A), the constituent unit (B), and the constituent unit (C) in the polymer is 90% by mass or more, the content of the constituent unit (A) in the polymer is 50 to 90% by mass, the amine value of the polymer is 0 to 100 mg KOH / g, the number average molecular weight (Mn2) of the polymer in polystyrene terms, as measured by gel permeation chromatography, is 8,000 to 35,000, and the phthalocyanine compound is a sulfonated copper phthalocyanine in which one or more sulfonic acid groups are bonded to a phthalocyanine skeleton. [2] The carbon dispersion according to [1], wherein the nitrogen-containing monomer (C) is a quaternary ammonium salt of dimethylaminoethyl (meth)acrylate, and the content of the constituent unit (C) in the polymer is 3 to 25% by mass. [3] The carbon dispersion according to [1], wherein the nitrogen-containing monomer (C) is a quaternary ammonium salt of dimethylaminoethyl (meth)acrylate having a halogen-free anion as a counterion. [4] The carbon dispersion according to any one of [1] to [3], wherein the conductive carbon black is acetylene black. [5] A carbon dispersion according to any one of [1] to [4], wherein the conductive carbon black content is 5 to 20% by mass, the polymer dispersant content is 10 to 150 parts by mass per 100 parts by mass of conductive carbon black, the phthalocyanine compound content is 3 to 20 parts by mass per 100 parts by mass of conductive carbon black, the number average particle diameter of the conductive carbon black measured by dynamic light scattering is 50 to 200 nm, and the viscosity at 25°C is 10.0 to 100.0 mPa·s. [Effects of the Invention]

[0008] According to the present invention, even when conductive carbon black is contained at a high concentration, it is possible to provide a carbon dispersion liquid that is low viscosity, in which the conductive carbon black is finely dispersed in an organic solvent in a good state, and in which the good dispersion state can be maintained for a long period of time, making it useful as a material for forming a conductive coating film. [Modes for carrying out the invention]

[0009] <Carbon dispersion> The embodiments of the present invention will be described below, but the present invention is not limited to the embodiments described below. One embodiment of the carbon dispersion of the present invention is a so-called organic solvent-based dispersion used to form a conductive coating film, comprising conductive carbon black, an organic solvent, a polymeric dispersant for dispersing conductive carbon black in the organic solvent, and a phthalocyanine compound. The polymeric dispersant is a polymer having a constituent unit (A) derived from a macromonomer (A), a constituent unit (B) derived from an aromatic vinyl monomer (B), and a constituent unit (C) derived from a nitrogen-containing monomer (C). The macromonomer (A) is a monomer in which a (meth)acryloyloxy group is bonded via a urea bond to one end of a polyalkylene glycol monomethyl ether chain having an alkylene group with 2 to 3 carbon atoms. The aromatic vinyl monomer (B) is at least one selected from the group consisting of styrene, α-methylstyrene, vinylnaphthalene, vinyltoluene, and acenaphthylene. The nitrogen-containing monomer (C) is at least one selected from the group consisting of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, vinylpyridine, and quaternary ammonium salts thereof. The phthalocyanine compound is a sulfonated copper phthalocyanine in which one or more sulfonic acid groups are bonded to a phthalocyanine skeleton. The details of the carbon dispersion of this embodiment will be described below.

[0010] (Conductive carbon black) Conductive carbon black (hereinafter also simply referred to as "carbon black") is an aggregate of fine particles obtained by the incomplete combustion of various hydrocarbons and carbon-containing compounds, which exhibits conductivity. Examples of carbon black include Ketjenblack and acetylene black. Among these, acetylene black, obtained from acetylene, is preferred due to its high purity, high crystallinity, and excellent conductivity.

[0011] The primary particle size of carbon black is preferably 20 to 50 nm. A carbon book having a continuous structure in which particles of such primary particle size are aggregated can be used. The primary particle size of carbon black can be observed and measured, for example, using a transmission electron microscope. The specific surface area of ​​carbon black is 30 to 150 m². 2 It is preferable that the amount is / g. Examples of commercially available acetylene black include Denka Black and Denka Black Li (both manufactured by Denka Co., Ltd.), which are listed below as product names. Examples of Ketjen Black include Ketjen Black EC300J and Ketjen Black EC600JD (both manufactured by Lion Specialty Chemicals), which are listed below as product names.

[0012] (Organic solvents) The organic solvent is a component that acts as a dispersion medium for dispersing the conductive carbon black, and conventionally known organic solvents can be used. As the organic solvent, in addition to non-aqueous organic solvents that substantially do not contain water, aqueous organic solvents that contain a small amount of water can be used.

[0013] Organic solvents 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; ethylene glycol, propylene Examples of glycol monoether solvents include glycol monoethers such as ethylene glycol, diethylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, diethylene glycol methyl 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; and the like.

[0014] Furthermore, reactive monomers can be used as organic solvents. By using reactive monomers as organic solvents, carbon dispersions useful as UV or electron beam curable inks, coatings, etc., can be obtained. Examples of reactive monomers include vinyl monomers such as (meth)acrylic monomers, as well as vinyl ether compounds, epoxy compounds, and oxetane compounds. In addition, reactive monomers may be used in combination with the aforementioned organic solvents (organic solvents other than reactive monomers).

[0015] (Polymer dispersant) The polymeric dispersant is a polymer (graft polymer) having a graft structure in which polyalkylene glycol monomethyl ether chains derived from macromonomer (A) are grafted onto a main chain containing aromatic rings and ionic amino groups. The main chain is adsorbed onto carbon black, and the grafted polyalkylene glycol monomethyl ether chains stably disperse the carbon black due to their solvent affinity and steric repulsion. Furthermore, due to the solubility of the polyalkylene glycol monomethyl ether chains, a carbon dispersion with low viscosity and excellent dispersibility can be obtained.

[0016] The polymer dispersant is a polymer having a structural unit (A) derived from a macromonomer (A) in which a (meth)acryloyloxy group is bonded via a urea bond to one end of a polyalkylene glycol monomethyl ether chain having an alkylene group with 2 to 3 carbon atoms. This macromonomer (A) can be obtained by reacting a polyalkylene glycol monomethyl ether monoamine having an alkylene group with 2 to 3 carbon atoms with a compound having a (meth)acryloyloxy group and an isocyanate group. The amino group of the polyalkylene glycol monomethyl ether monoamine reacts with the isocyanate group to form a urea bond. Thereby, a macromonomer (A) in which a (meth)acryloyloxy group is bonded via a urea bond to one end of a polyalkylene glycol monomethyl ether chain can be obtained. Since the urea group formed at this time has hydrogen bonding properties, by using a polymer having a structural unit (A) derived from the macromonomer (A) as a polymer dispersant, an effect of improving the adsorption property to carbon black is expected.

[0017] Examples of the polyalkylene glycol monomethyl ether monoamine include polyethylene glycol monomethyl ether monoamine, polypropylene glycol monomethyl ether monoamine, and polyethylene glycol polypropylene glycol monomethyl ether monoamine. Among them, polyethylene glycol polypropylene glycol monomethyl ether monoamine is preferable because the degree of hydrophilicity can be set by changing the composition ratio of polyethylene glycol (PEG) and polypropylene glycol (PPG).

[0018] Examples of the compound having a (meth)acryloyloxy group and an isocyanate group include (meth)acryloyloxyethyl isocyanate and (meth)acryloyloxyethoxyethyl isocyanate. Further, (meth)acrylates in which the isocyanate of these compounds is blocked can also be used.

[0019] The number average molecular weight (Mn1) of the macromonomer (A) in terms of polystyrene measured by gel permeation chromatography (GPC) is 500 to 5,000, preferably 1,000 to 4,500. When the number average molecular weight of the macromonomer (A) is less than 500, steric repulsion becomes insufficient, making it difficult to improve dispersion stability. On the other hand, when the number average molecular weight of the macromonomer (A) exceeds 5,000, the molecular weight of the polymer dispersant (polymer) becomes too large. Therefore, it is necessary to increase the amount of the polymer dispersant with respect to carbon black, and the viscosity of the carbon dispersion may increase excessively.

[0020] The macromonomer (A) is a high molecular weight monomer with a narrow molecular weight distribution and relatively uniform molecular weights. The molecular weight distribution (PDI = weight average molecular weight (Mw) / number average molecular weight (Mn1)) of the macromonomer (A) is 1.5 or less, preferably less than 1.3, more preferably less than 1.2, and particularly preferably less than 1.1. The weight average molecular weight (Mw) used for calculating the molecular weight distribution (PDI) is a value in terms of polystyrene measured by GPC, similar to the number average molecular weight (Mn1). When the molecular weight distribution (PDI) of the macromonomer (A) exceeds 1.5, it is likely to contain many components outside the range of the aforementioned number average molecular weight (Mn1), and the effect of improving dispersibility becomes insufficient. Also, if the molecular weight distribution is too wide, many branched chains with small molecular weights or large molecular weights will branch off from the main chain, making it difficult to set the molecular weight of the polymer dispersant within a predetermined range.

[0021] The polymer dispersant is a polymer having a structural unit (B) derived from an aromatic vinyl monomer (B). Carbon black has a six-membered ring graphite structure formed by covalent bonds of carbon atoms. Therefore, by using a polymer having a main chain into which an aromatic ring is introduced as the polymer dispersant, it is considered that the polymer is likely to adsorb to carbon black by π-π stacking.

[0022] The aromatic vinyl monomer (B) is at least one selected from the group consisting of styrene, α-methylstyrene, vinylnaphthalene, vinyltoluene, and acenaphthylene. Among these, styrene and α-methylstyrene are preferred due to their readily available and versatile properties, and α-methylstyrene is even more preferred. The radical generated when the polymer radical end is added to α-methylstyrene is a stable tertiary radical in which an aromatic ring and a methyl group are bonded. This tertiary radical has difficulty attacking the next monomer due to steric hindrance and has the function of terminating polymerization. Therefore, by using α-methylstyrene as the aromatic vinyl monomer (B), the molecular weight of the resulting polymer (main chain) can be easily controlled.

[0023] The polymer dispersant is a polymer having a constituent unit (C) derived from a nitrogen-containing monomer (C). Since there are virtually no active groups on the particle surface of carbon black such as acetylene black, the adsorption capacity of the polymer is often insufficient if only the aromatic ring in the constituent unit (B) is used, and the polymer tends to detach from the carbon black during dispersion, resulting in insufficient dispersion stability. The carbon dispersion of this embodiment contains sulfonated copper phthalocyanine (phthalocyanine compound), in which one or more sulfonic acid groups are bonded to a phthalocyanine skeleton. Because phthalocyanine compounds are polyaromatic and solvent-insoluble, they readily adsorb to carbon black, and sulfonic acid groups can be imparted to the particle surface of carbon black. It is thought that the ionic bonding between the sulfonic acid groups imparted to the particle surface of carbon black and the nitrogen atom in the constituent unit (C) makes it difficult for the polymer used as a polymer dispersant to detach from the carbon black. In addition, quaternary ammonium bases are solvent-insoluble groups. Therefore, when a quaternary ammonium base is introduced into the main chain of a polymer used as a polymer dispersant, the highly polar quaternary ammonium salt is likely to electrically interact with carbon black, making the polymer more susceptible to adsorption by the carbon black.

[0024] The nitrogen-containing monomer (C) is at least one selected from the group consisting of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, vinylpyridine, and quaternary ammonium salts thereof. Quaternary ammonium salts include (meth)acryloyloxyethyl trimethyl chloride, (meth)acryloyloxyethyl trimethyl bromide, (meth)acryloyloxyethyl benzyldimethyl chloride, (meth)acryloyloxyethyl naphthylmethyldimethyl chloride, (meth)acryloyloxyethyl benzyldimethyl bromide, (meth)acryloyloxyethyl benzyldiethyl chloride, (meth)acryloyloxyethyl benzyldiethyl bromide, and quaternary ammonium salts having halogen anions such as vinylpyridinium methyl iodide; quaternary ammonium salts having hydroxide ions such as (meth)acryloyloxyethyl trimethyl hydroxide and (meth)acryloyloxyethyl benzyldimethyl hydroxide; (meth)acryloyloxyethyl benzyldimethylbis(trifluoromethanesulfonyl)imide, (meth)acryloyloxyethyl Examples include quaternary ammonium salts having a fluorine-containing anion such as rubenzyldimethyl triflate, (meth)acryloyloxyethyl benzyldimethyltetrafluoroborate, and (meth)acryloyloxyethyl benzyldimethylhexafluorophosphate; quaternary ammonium salts with anions substantially free of halogen atoms as counterions such as dimethylaminoethyl (meth)acrylate dimethyl sulfate, dimethylaminoethyl (meth)acrylate diethyl sulfate, diethylaminoethyl (meth)acrylate dimethyl sulfate, diethylaminoethyl (meth)acrylate diethyl sulfate, (meth)acryloyloxyethyl benzyldimethyltoluenesulfonate, (meth)acryloyloxyethyl benzyldimethyltetraphenylborate, and (meth)acryloylethyl trimethylacetate; and anion-cation type quaternary ammonium salts such as betaine and sulfobetaine. Among these, quaternary ammonium salts of dimethylaminoethyl (meth)acrylate are preferred because they are readily available and there is a wide variety of quaternary ammonium salts available.Furthermore, when the nitrogen-containing monomer (C) is a quaternary ammonium salt of dimethylaminoethyl (meth)acrylate, the content of the constituent unit (C) in the polymer is preferably 3 to 25% by mass.

[0025] When using a carbon dispersion as a component of electronic materials, the presence of halogen elements as impurities may degrade the performance of the electronic materials. Therefore, from the viewpoint of effectively avoiding a degradation in the performance of electronic materials, the nitrogen-containing monomer (C) is preferably a quaternary ammonium salt of dimethylaminoethyl (meth)acrylate, which has a halogen-free anion as a counterion.

[0026] By using a nitrogen-containing monomer (C), a polymer having a main chain into which amino groups have been introduced (graft polymer) can be obtained. The content of amino groups in the polymer can be defined by the amine value of the polymer. The amine value of the polymer used as a polymeric dispersant is 0 to 100 mg KOH / g, preferably 0.1 to 95 mg KOH / g. As described above, the polymeric dispersant ionically bonds with a phthalocyanine compound having a sulfonic acid group (sulfonated copper phthalocyanine) and adsorbs onto carbon black via the phthalocyanine compound. If the amine value of the polymer (polymeric dispersant) exceeds 100 mg KOH / g, the dispersibility of carbon black decreases.

[0027] The amine value of a polymer is defined as the number of moles of hydrochloric acid (HCl) and the equivalent amount of potassium hydroxide (mg) required to neutralize the amino groups in 1 g of polymer. The amine value of polymer dispersants can be measured by conventionally known methods. Specifically, these include titrating with a 0.1 mol / L hydrochloric acid / isopropanol solution as the titrant and bromophenol blue as the indicator; or measuring the potential difference using a similar titrant. Furthermore, it can also be calculated from the compound composition and polymerization rate.

[0028] The total content of constituent units (A), (B), and (C) in the polymer is 90% by mass or more, preferably 100% by mass. In other words, it is preferable that the polymer dispersant is a polymer substantially composed only of constituent units (A), (B), and (C).

[0029] The polymer may further have other constituent units besides constituent unit (A), constituent unit (B), and constituent unit (C). Preferably, the content of other constituent units in the polymer is less than 10% by mass. Examples of monomers constituting the other constituent units (other monomers) include (meth)acrylate monomers such as (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate; (meth)acrylamide monomers such as (meth)acrylamide and dimethyl (meth)acrylamide; (meth)acrylonitrile; vinyl alkanoate monomers such as vinyl acetate and vinyl butyrate; amide vinyl monomers such as N-vinylpyrrolidone and N-vinylcarbazole; and the like.

[0030] The content of constituent unit (A) in the polymer is 50 to 90% by mass, preferably 55 to 85% by mass. In other words, polymer dispersants have a relatively high proportion of constituent unit (A) derived from macromonomers (A). A high proportion of constituent unit (A) derived from macromonomers (A) means that the proportion of the main chain adsorbed to carbon black is relatively low. In polymers with such a structure, the parts that adsorb to carbon black (main chain) and the parts that dissolve in organic solvents (graft chains (branched chains)) have clearly defined roles, and it is thought that steric repulsion further improves the dispersion stability of carbon black. If the proportion of constituent unit (A) in the polymer is less than 50% by mass, the proportion of the main chain increases relatively, which may result in a structure and molecular weight that is not the desired one. On the other hand, if the proportion of constituent unit (A) in the polymer exceeds 90% by mass, there are too few parts that adsorb to carbon black (aromatic rings, amino groups, quaternary ammonium bases), which reduces the dispersibility of carbon black.

[0031] The number-average molecular weight (Mn2) of the polymer dispersant (polymer) in polystyrene equivalent, as measured by GPC, is 8,000 to 35,000, preferably 9,000 to 33,000. If the number-average molecular weight of the polymer is less than 8,000, the molecular weight is too small, and it tends to desorb quickly even after adsorption to carbon black. On the other hand, if the number-average molecular weight of the polymer is greater than 35,000, the amount (number of moles) of the polymer dispersant is insufficient, and the amount of polymer dispersant relative to the carbon black tends to be excessive, which can cause the viscosity of the carbon dispersion to increase excessively.

[0032] Polymers used as polymer dispersants can be synthesized according to conventionally known methods. For example, they can be synthesized by radical polymerization using peroxide or azo-based radical polymerization initiators and, if necessary, chain transfer agents such as thiols. They can also be synthesized by conventionally known living radical polymerization methods. Specifically, examples include the NMP method using nitrooxide as a stabilized radical; atom transfer radical polymerization utilizing the redox reaction of metal complexes; reversible chain transfer polymerization using dithioesters or dithiocarbamates; organotellurium-controlled living radical polymerization using organotellurium; and reversible transfer catalytic polymerization using halides as initiators and an organic catalyst. These polymerization methods may be bulk polymerization or solution polymerization using solvents. In the case of solution polymerization, the obtained polymer solution can be used as is. Alternatively, the polymer can be isolated by volatilizing the solvent from the polymer solution or by mixing the polymer solution with a poor solvent.

[0033] (Phthalocyanine compounds) Phthalocyanine compounds are sulfonated copper phthalocyanines, in which one or more sulfonic acid groups are bonded to a phthalocyanine skeleton, and function as so-called synergists. As mentioned above, since phthalocyanine compounds are polyaromatic and solvent-insoluble, they can be adsorbed onto carbon black, introducing sulfonic acid groups to the surface of carbon black particles. Then, the sulfonic acid groups attached to the surface of the carbon black particles form ionic bonds with nitrogen atoms such as amino groups in the constituent unit (C), making it difficult for the polymer to detach from the carbon black, and a low-viscosity carbon dispersion can be obtained in which carbon black is stably dispersed in an organic solvent for a long period of time. In addition, the phthalocyanine skeleton of sulfonated copper phthalocyanine may also have groups other than sulfonic acid groups bonded to it, such as halogen atoms, hydroxyl groups, and carboxyl groups.

[0034] (Other ingredients) The carbon dispersion may further contain components other than those described above (other components). Examples of other components include various additives and resins. Examples of additives include oil-soluble dyes, pigments, ultraviolet absorbers, light stabilizers, antioxidants, leveling agents, defoamers, preservatives, fungicides, photopolymerization initiators, and pigment dispersants other than the polymer dispersants mentioned above. Examples of 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, polyphenol resins, polyurea resins, and polyethersulfone resins.

[0035] (Carbon dispersion) The content of conductive carbon black in the carbon dispersion is preferably 5 to 20% by mass, and more preferably 8 to 16% by mass. If the content of conductive carbon black is less than 5% by mass, the amount of conductive carbon black will be too small, which may make it unsuitable for practical use. On the other hand, if the content of conductive carbon black exceeds 20% by mass, the viscosity of the dispersion may increase excessively due to the nano-size of the conductive carbon black particles, making it difficult to use.

[0036] In the carbon dispersion, the content of the polymer dispersant is preferably 10 to 150 parts by mass, and more preferably 20 to 120 parts by mass, per 100 parts by mass of conductive carbon black. Furthermore, the content of the phthalocyanine compound in the carbon dispersion is preferably 3 to 20 parts by mass, per 100 parts by mass of conductive carbon black. By using conductive carbon black, polymer dispersant, and phthalocyanine compound in the above-mentioned ratios, a carbon dispersion in which the conductive carbon black is dispersed more stably can be obtained. If the amount of polymer dispersant or phthalocyanine compound is too small relative to the conductive carbon black, the dispersion stability may be somewhat insufficient. On the other hand, if the amount of polymer dispersant or phthalocyanine compound is too large relative to the conductive carbon black, the dispersion tends to thicken, and the proportion of conductive carbon black tends to be relatively low.

[0037] A key feature of the carbon dispersion of this embodiment is its low viscosity. Due to its low viscosity, it is easy to blend with various components and is suitable as a material for manufacturing various products, including paints and inks. Specifically, the viscosity of the carbon dispersion of this embodiment at 25°C is preferably 10.0 to 100.0 mPa·s.

[0038] Carbon dispersions can be easily prepared by mixing conductive carbon black, an organic solvent, a polymeric dispersant, and a phthalocyanine compound, and then dispersing them. The dispersion method is not particularly limited, and conventionally known methods can be employed. For example, dispersion methods such as disperser stirring, kneading using a three-roll mixer, ultrasonic dispersion, bead mill dispersion, emulsifiers, and high-pressure homogenizers can be used. Among these, bead mill dispersion, ultrasonic dispersion, and high-pressure homogenizers are preferred because they have a high dispersion effect.

[0039] The dispersibility of conductive carbon black in a carbon dispersion can be evaluated, for example, by measuring the absorbance of the dispersion using a spectrophotometer, or by measuring the average particle size of the carbon black in the dispersion using a dynamic light scattering particle size distribution analyzer. Furthermore, the dispersibility of carbon black in a carbon dispersion can also be evaluated by checking for the presence or absence of aggregates after prolonged standing. Additionally, the dispersibility of carbon black in a carbon dispersion can be evaluated by observing the state of the carbon dispersion dropped onto a glass plate using an electron microscope, or by measuring the electrical conductivity of a coating film formed using the carbon dispersion. In this embodiment, the number-average particle size of conductive carbon black measured by the dynamic light scattering method is preferably 50 to 200 nm. That is, one of the important features of this embodiment is that so-called nano-sized carbon black is dispersed in a good state. By dispersing carbon black at the nano-size, a carbon dispersion can be made capable of producing articles and other items that exhibit high conductivity.

[0040] The carbon dispersion of this embodiment contains conductive carbon black, preferably nano-sized conductive carbon black, in a well-dispersed state. Therefore, by using the carbon dispersion of this embodiment, conductivity can be imparted to, for example, paints, inks, and resin molded products. Furthermore, the carbon dispersion of this embodiment is expected to be used as a conductive material and a thermal conductive agent, as well as an antistatic material. [Examples]

[0041] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0042] <Synthesis of polymer dispersants (polymers)> (Synthesis Example 1) (a) Synthesis of macromonomer (A) 100.0 parts (0.045 mol) of one-terminated amination polypropylene glycol polyethylene glycol monomethyl ether copolymer (trade name "Jeffermin M2005", manufactured by Huntsman, measured amine value 25.25 mg KOH / g) (M2005) and 100.0 parts of propylene glycol monomethyl ether acetate (PGMAc) were placed in a reaction vessel and stirred at room temperature for 10 minutes to homogenize. 7.0 parts (0.045 mol) of 2-isocyanatoethyl methacrylate (trade name "Karenz MOI", manufactured by Resonaq) (MOI) and 7.0 parts of PGMAc were placed in a separate container to prepare a mixture. The prepared mixture was added dropwise to the reaction vessel over 30 minutes using a dropping funnel. A gradual exothermic reaction was observed immediately after the start of the dropwise addition. The IR absorption of the sampled contents was measured using an infrared spectrophotometer, confirming that the absorption of the isocyanate group derived from MOI had almost completely disappeared and that urea bonds had been formed. Furthermore, the amine value measured by a potentiometric automatic titrator using a 0.1 mol / L 2-propanolic hydrochloric acid solution was 0.1 mg KOH / g, confirming that the reaction between the amino group and the isocyanate group was almost complete. From the above, it was confirmed that MC-1, a macromonomer (A) in which a methacryloyloxy group was bonded to one end of a polypropylene glycol polyethylene glycol (PPG / PEG) monomethyl ether chain via a urea bond, was produced. The solid content of MC-1, measured using a moisture meter, was 50.0%. The number-average molecular weight (Mn) in polystyrene terms, measured by GPC with tetrahydrofuran (THF) as the developing solvent, was 3,500, and the degree of dispersion (PDI = weight-average molecular weight (Mw) / number-average molecular weight (Mn)) was 1.08.

[0043] (b) Synthesis of graft polymers 214.0 parts of MC-1, 29.1 parts of PGMAc, 1.8 parts of α-methylstyrene (αMS), 20.2 parts of styrene (St), and 3.6 parts of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) were placed in a reaction vessel and heated to 75°C while bubbling with nitrogen. When the temperature reached 70°C, 3.0 parts of 2,2'-Azobis(isobutyrate)dimethyl (trade name "V-601", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (V601) were added and polymerization was carried out at 75°C for 4 hours. Furthermore, 0.5 parts of V601 were added and polymerization was carried out at 75°C for 4 hours to form a polymer. The polymer had a manganese content of 15,600, a PDI of 2.28, and a peak-top molecular weight (PT) of 27,200, with almost no peaks derived from MC-1 used as a raw material. The solid content, measured using a moisture meter, was 49.8%, and the amine value, calculated based on resin purity, was 9.3 mgKOH / g.

[0044] Next, a mixed solution of 2.9 parts propylene glycol monomethyl ether (PGM) and 2.9 parts benzyl chloride (BzCl) was added dropwise to the reaction apparatus at room temperature over 10 minutes. After addition, the mixture was heated to 80°C and held for 5 hours to obtain the graft polymer, polymer dispersant G-1. The obtained graft polymer (polymer dispersant G-1) had a manganese content of 15,700, a PDI of 2.18, and a PT of 26,900. The solid content was 50.0%, and the amine value, calculated on a resin purity basis, was 0.1 mg KOH / g.

[0045] (Synthesis Examples 2-5) Polymer dispersants G-2 to G-5 were obtained in the same manner as in Synthesis Example 1 described above, except that the formulations (in parts) were as shown in Table 1. The meaning of the abbreviations in Table 1 is shown below. • M1000: End-terminated amination polypropylene glycol polyethylene glycol monomethyl ether, trade name "Jeffermin M1000", manufactured by Huntsman. • M41: End-terminated amination polypropylene glycol polyethylene glycol monomethyl ether, trade name "Genamine M41 / 2000", manufactured by Clariant. • M3085: End-terminated amination polypropylene glycol polyethylene glycol monomethyl ether, trade name "Jeffermin M3085", manufactured by Huntsman. VN: Vinyl naphthalene • ACEN: Acenaphthylene VT: Vinyltoluene • DEAEMA: 2-(N,N-diethylamino)ethyl methacrylate • VP: Vinylpyridine • DMQ: Benzyl chloride salt of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) • DEQ: Benzyl chloride salt of 2-(N,N-diethylamino)ethyl methacrylate (DEAEMA)

[0046] TIFF2026072162000001.tif232170

[0047] (Synthesis Example 6) (a) Synthesis of macromonomer (A) MC-1, a macromonomer (A), was obtained in the same manner as in Synthesis Example 1 described above. The obtained MC-1 had a Mn of 3,400 and a PDI of 1.09.

[0048] (b) Synthesis of graft polymers The obtained MC-1 (214.0 parts), PGMAc (29.1 parts), αMS (1.8 parts), St (20.2 parts), and DMAEMA (3.6 parts) were placed in a reaction vessel and heated to 75°C while bubbling with nitrogen. At 70°C, 3.0 parts of V601 were added, and polymerization was carried out at 75°C for 4 hours. After adding another 0.5 parts of V601, polymerization was carried out at 75°C for 4 hours to form a polymer. The polymer had a Mn of 15,400, a PDI of 2.24, and a PT of 26,800, with almost no peaks derived from the MC-1 used as a raw material. The solid content, measured using a moisture meter, was 49.9%, and the amine value, calculated on a resin purity basis, was 9.4 mgKOH / g.

[0049] Next, a mixed solution of 3.5 parts PGM and 3.5 parts diethyl sulfate (DES) was added dropwise to the reaction apparatus at room temperature over 10 minutes. After addition, the mixture was heated to 80°C and held for 5 hours to obtain the graft polymer, polymer dispersant G-6. The obtained graft polymer (polymer dispersant G-6) had a manganese content of 14,700, a PDI of 2.21, and a PT of 26,900. The solid content was 49.9%, and the amine value, calculated on a resin purity basis, was 0.1 mg KOH / g. The obtained polymer dispersant G-6 is a graft polymer that uses an anion without halogen atoms as a counterion.

[0050] (Synthesis examples 7, 8) Polymer dispersants G-7 and G-8 were obtained in the same manner as in Synthesis Example 6 described above, except for the formulation shown in Table 2 (unit: parts). The meaning of the abbreviations in Table 2 is as follows. • DMDES: Diethyl sulfate of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) • DEDES: Diethyl sulfate of 2-(N,N-diethylamino)ethyl methacrylate (DEAEMA)

[0051] TIFF2026072162000002.tif240170

[0052] (Comparative Synthesis Example 1) (a) Synthesis of macromonomer (A) MC-1, a macromonomer (A), was obtained in the same manner as in Synthesis Example 1 described above. The obtained MC-1 had a Mn of 3,500 and a PDI of 1.10.

[0053] (b) Synthesis of graft polymers 214.0 parts of MC-1, 28.3 parts of PGMAc, 1.0 part of the chain transfer agent laurylthiol (LSH), 20.2 parts of methyl methacrylate (MMA), and 3.6 parts of DMAEMA were placed in a reaction vessel and heated to 75°C while bubbling with nitrogen. At 70°C, 3.0 parts of V601 were added, and polymerization was carried out at 75°C for 4 hours. After adding another 0.5 parts of V601, polymerization was carried out at 75°C for 4 hours to form a polymer. The polymer had a Mn of 17,300, a PDI of 2.05, and a PT of 34,900, with almost no peaks derived from the MC-1 used as a raw material. The solid content, measured using a moisture meter, was 49.9%, and the amine value, calculated on a resin purity basis, was 9.8 mgKOH / g.

[0054] Next, a mixed solution of 2.9 parts PGM and 2.9 parts BzCl was added dropwise to the reaction apparatus at room temperature over 10 minutes. After addition, the mixture was heated to 80°C and held for 5 hours to obtain the graft polymer, polymer dispersant R-1. The obtained graft polymer (polymer dispersant R-1) had a manganese content of 16,800, a PDI of 2.21, and a PT of 31,700. The solid content was 49.8%, and the amine value, calculated on a resin purity basis, was 0.1 mg KOH / g.

[0055] (Comparative synthesis examples 2-4) Polymer dispersants R-2 to R-4 were obtained in the same manner as in Comparative Synthesis Example 1 described above, except that the formulations (units: parts) were as shown in Table 3.

[0056] TIFF2026072162000003.tif247170

[0057] <Preparation of carbon dispersion> (Example 1) A carbon black dispersion was prepared as follows, using carbon black (acetylene black, trade name "Denka Black Li-100", manufactured by Denka Co., Ltd.) (Li-100) as the dispersion medium, PGMAc as the dispersion medium, and the previously prepared polymer dispersant G-1 as the dispersant. 8.0 parts of carbon black (acetylene black, trade name "Denka Black Li-100", manufactured by Denka Co., Ltd.) (Li-100), 75.2 parts of PGMAc, 16.0 parts of polymer dispersant G-1 (resin solids content: 50.0%), and 0.8 parts of Synagist (sulfonated copper phthalocyanine, trade name "Solspers 12000", manufactured by Lubrizol) (12000) were placed in a poly bottle. 200 parts of zirconia beads with a diameter of 0.5 mmφ were then added, and the mixture was dispersed using ScanDex for 30 minutes to obtain a carbon dispersion (CB dispersion-1).

[0058] (Examples 2-14, Comparative Examples 1-7) Carbon dispersions (CB dispersions-2 to 21) were prepared in the same manner as in Example 1 described above, except for the formulation shown in Table 4. The meaning of the abbreviations in Table 4 is shown below. • 3030B: Product name "#3030B", manufactured by Mitsubishi Chemical Corporation. • 4500: Product name "Toka Black #4500", manufactured by Tokai Carbon Co., Ltd. • EC300J: Product name "Ketjenblack EC300J", manufactured by Lion Specialty Chemicals.

[0059] TIFF2026072162000004.tif160170

[0060] <Rating> (Measurement of number-average particle size) The number-average particle size of carbon black in a CB dispersion was measured using a dynamic light scattering particle size distribution analyzer. The results are shown in Table 5.

[0061] (Measurement of viscosity, evaluation of viscosity stability) The viscosity of the CB dispersion was measured immediately after dispersion (initial) and after standing for 10 days using an E-type viscometer (measurement conditions: 25°C, rotor speed 100 rpm). The results are shown in Table 5. Furthermore, the percentage change in viscosity after standing for 10 days (viscosity change rate (%)) was calculated relative to the initial viscosity, and the viscosity stability of the CB dispersion was evaluated according to the evaluation criteria shown below. The results are shown in Table 5. ◎: The viscosity change rate was less than 5%. ○: The viscosity change rate was between 5% and less than 10%. ×: The viscosity change rate was 10% or more.

[0062] (Checking for the presence or absence of aggregates) The state of the CB dispersion after standing for 10 days was observed under an optical microscope (200x magnification) to check for the presence or absence of aggregates. The results are shown in Table 5.

[0063] TIFF2026072162000005.tif166170 [Industrial applicability]

[0064] The carbon dispersion of the present invention is useful as a material for forming conductive coating films, and is expected to be used in conductive and antistatic applications. Furthermore, the carbon dispersion of the present invention is also useful as a material for manufacturing paints, inks, stationery, resin molded products, battery coatings, and display partition materials, for example.

Claims

1. A carbon dispersion used to form a conductive coating film, It contains conductive carbon black, an organic solvent, a polymeric dispersant for dispersing the conductive carbon black in the organic solvent, and a phthalocyanine compound. The polymer dispersant comprises a constituent unit (A) derived from a macromonomer (A) in which a (meth)acryloyloxy group is bonded via a urea bond to one end of a polyalkylene glycol monomethyl ether chain having an alkylene group having 2 to 3 carbon atoms, A constituent unit (B) derived from at least one aromatic vinyl monomer (B) selected from the group consisting of styrene, α-methylstyrene, vinylnaphthalene, vinyltoluene, and acenaphthalene, A polymer having a constituent unit (C) derived from at least one nitrogen-containing monomer (C) selected from the group consisting of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, vinylpyridine, and quaternary ammonium salts thereof, The number-average molecular weight (Mn1) of the macromonomer (A) in polystyrene equivalent, as measured by gel permeation chromatography, is 500 to 5,000, and the molecular weight distribution (weight-average molecular weight / number-average molecular weight) is 1.5 or less. The total content of the constituent unit (A), the constituent unit (B), and the constituent unit (C) in the polymer is 90% by mass or more. The polymer contains 50 to 90% by mass of the constituent unit (A). The amine value of the polymer is 0 to 100 mg KOH / g. The number-average molecular weight (Mn²) of the polymer, measured by gel permeation chromatography in terms of polystyrene, is 8,000 to 35,000. A carbon dispersion in which the phthalocyanine compound is a sulfonated copper phthalocyanine in which one or more sulfonic acid groups are bonded to a phthalocyanine skeleton.

2. The nitrogen-containing monomer (C) is a quaternary ammonium salt of dimethylaminoethyl (meth)acrylate. The carbon dispersion according to claim 1, wherein the content of the constituent unit (C) in the polymer is 3 to 25% by mass.

3. The carbon dispersion according to claim 1, wherein the nitrogen-containing monomer (C) is a quaternary ammonium salt of dimethylaminoethyl (meth)acrylate having a halogen-free anion as a counterion.

4. The carbon dispersion according to claim 1, wherein the conductive carbon black is acetylene black.

5. The content of the conductive carbon black is 5 to 20% by mass. The amount of the polymer dispersant relative to 100 parts by mass of the conductive carbon black is 10 to 150 parts by mass. The content of the phthalocyanine compound per 100 parts by mass of the conductive carbon black is 3 to 20 parts by mass. The number-average particle size of the conductive carbon black, as measured by the dynamic light scattering method, is 50 to 200 nm. A carbon dispersion according to any one of claims 1 to 4, wherein the viscosity at 25°C is 10.0 to 100.0 mPa·s.

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