Carbon nanotube dispersion liquid

Abstract

This invention provides a carbon nanotube dispersion that contains carbon nanotubes, a dispersant, a solvent, and a polymer which has a partial structure represented by formula (P1) on a side chain. (In the formula, L represents -O- or -NH-, R represents an alkylene group having 1-20 carbon atoms, T represents a substituted or unsubstituted amino group, a nitrogen-containing heteroaryl group having 2-20 carbon atoms, or a nitrogen-containing aliphatic heterocyclic group having 2-20 carbon atoms, and * represents a bond.)

Description

Technical Field

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

Background Art

[0002] Carbon nanotubes (hereinafter also abbreviated as CNTs) are being studied for potential applications in a wide range of fields as a promising material for nanotechnology. Their applications are roughly classified into two methods: one is to use a single CNT itself, such as in a transistor or a microscope probe; the other is to use a large number of CNTs together as a bulk, such as in an electron-emitting electrode, a fuel cell electrode, or a conductive composite in which CNTs are dispersed.

[0003] When using a single CNT, a method is used in which the CNT is added to a solvent and irradiated with ultrasonic waves, and then only the CNTs that are singly dispersed by electrophoresis or the like are taken out. On the other hand, in a conductive composite used in bulk, it is necessary to disperse it well in a polymer serving as a matrix material. However, generally, CNTs have a problem of being difficult to disperse, and in a normal composite, the CNTs are used with incomplete dispersion, so it is hard to say that the performance of CNTs is fully exhibited. Furthermore, this problem also makes various applications of CNTs difficult. For this reason, various methods for improving the dispersibility by surface modification, surface chemical modification, etc. of CNTs have been studied.

[0004] As a method for dispersing such CNTs, a method of attaching poly((m-phenylene vinylene)-co-(dioctoxy-p-phenylene vinylene)) having a coiled structure to the CNT surface (see, for example, Patent Document 1) has been proposed. Here, it is possible to disperse CNTs in isolation in an organic solvent, and it shows a state where a polymer is attached to one CNT, but aggregation occurs after being dispersed to a certain extent, and the CNTs are collected as a precipitate, and it was not possible to store the CNTs in a dispersed state for a long time.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a carbon nanotube dispersion liquid in which a good dispersion state of CNTs in a medium such as water and a hydrophilic solvent is maintained and the CNTs can be stably dispersed.

Means for Solving the Problems

[0007] As a result of intensive studies to achieve the above object, the present inventors have found that a polymer having a specific partial structure in the side chain improves the dispersibility of CNTs in a dispersion liquid containing CNTs, a dispersant, and a solvent, and effectively suppresses the aggregation of the CNTs, and thus completed the present invention.

[0008] That is, the present invention provides the following carbon nanotube dispersion liquid. 1. A carbon nanotube dispersion liquid containing a carbon nanotube, a dispersant, a solvent, and a polymer having a partial structure represented by the following formula (P1) in the side chain.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a carbon nanotube dispersion in which a good dispersion state of CNTs in a medium such as water and hydrophilic solvents is maintained, and the CNTs can be stably dispersed. Moreover, in a dispersion containing CNTs, a dispersant, and a solvent, aggregation of CNTs is suppressed by a simple means of adding a polymer having a specific partial structure in the side chain, and a good dispersion state can be maintained, thus contributing to an improvement in production efficiency.

Embodiments for Carrying Out the Invention

[0010] The carbon nanotube dispersion according to the present invention (hereinafter simply referred to as the dispersion) is characterized by containing CNT, a dispersant, a solvent, and a polymer having a partial structure represented by the following formula (P1) in the side chain (hereinafter sometimes referred to as the P1 polymer).

[0011]

Chemical formula

[0012] In the formula, L represents -O- or -NH-, R represents an alkylene group having 1 to 20 carbon atoms, and T represents a substituted or unsubstituted amino group, a nitrogen-containing heteroaryl group having 2 to 20 carbon atoms, or a nitrogen-containing aliphatic heterocyclic group having 2 to 20 carbon atoms. * represents a bond.

[0013] The alkylene group having 1 to 20 carbon atoms may be linear, branched, or cyclic. For example, it includes a methylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, an octadecylene group, a nonadecylene group, an eicosanylene group, and the like. In the present invention, an alkylene group having 1 to 10 carbon atoms is preferred, an alkylene group having 1 to 8 carbon atoms is more preferred, and an alkylene group having 1 to 3 carbon atoms is even more preferred.

[0014] As the substituted or unsubstituted amino group, a group represented by the following (A1) is preferred.

[0015]

Chemical formula

[0016] As the alkyl group having 1 to 20 carbon atoms, any of linear, branched, and cyclic forms may be used. For example, linear or branched alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group; cyclic alkyl groups having 3 to 20 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, bicyclobutyl group, bicyclopentyl group, bicyclohexyl group, bicycloheptyl group, bicyclooctyl group, bicyclononyl group, bicyclodecyl group can be mentioned.

[0017] Said R a1 and R a2 are preferably a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a phenyl group, more preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a phenyl group, and even more preferably a methyl group. Also, said R a1 and R a2 may be the same as or different from each other, but it is more preferably the same group.

[0018] Examples of the nitrogen-containing heteroaryl group having 2 to 20 carbon atoms include 1-imidazolyl group, 2-imidazolyl group, 4-imidazolyl group, 1-pyridyl group, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, pyrazin-1-yl group, pyrazin-2-yl group, pyrimidin-1-yl group, pyrimidin-2-yl group, pyrimidin-4-yl group, pyrimidin-5-yl group, pyridazin-1-yl group, pyridazin-3-yl group, pyridazin-4-yl group, pyridazin-5-yl group, 1,2,3-triazin-4-yl group, 1,2,3-triazin-5-yl group, 1,2,4-triazin-3-yl group, 1,2,4-triazin-5-yl group, 1,2,4-triazin-6-yl group, 1,3,5-triazin-2-yl group, 1,2,4,5-tetrazin-3-yl group, 1,2,3,4-tetrazin-5-yl group, quinolin-1-yl group, quinolin-2-yl group, quinolin-3-yl group, quinolin-4-yl group, quinolin-5-yl group, quinolin-6-yl group, quinolin-7-yl group, quinolin-8-yl group, isoquinolin-1-yl group, isoquinolin-2-yl group, isoquinolin-3-yl group, isoquinolin-4-yl group, isoquinolin-5-yl group, isoquinolin-6-yl group, isoquinolin-7-yl group, isoquinolin-8-yl group, quinoxalin-1-yl group, quinoxalin-2-yl group, quinoxalin-5-yl group, quinoxalin-6-yl group, quinazolin-1-yl group, quinazolin-2-yl group, quinazolin-3-yl group, quinazolin-4-yl group, quinazolin-5-yl group, quinazolin-6-yl group, quinazolin-7-yl group, quinazolin-8-yl group, cinnolin-1-yl group, cinnolin-2-yl group, cinnolin-3-yl group, cinnolin-4-yl group, cinnolin-5-yl group, cinnolin-6-yl group, cinnolin-7-yl group, cinnolin-8-yl group.

[0019] Examples of the nitrogen-containing aliphatic heterocyclic group having 2 to 20 carbon atoms include a group having an aziridine ring, a group having an azetidine ring, a group having a pyrrolidine ring, a group having a piperidine ring, a group having a hexamethyleneimine ring, a group having an imidazolidine ring, a group having a piperazine ring, and a group having a pyrazolidine ring. Specific examples of the nitrogen-containing aliphatic heterocyclic group include an aziridin-1-yl group, an aziridin-2-yl group, an azetidin-1-yl group, an azetidin-2-yl group, an azetidin-3-yl group, a pyrrolidin-1-yl group, a pyrrolidin-2-yl group, a pyrrolidin-3-yl group, a piperidin-1-yl group, a piperidin-2-yl group, a piperidin-3-yl group, a piperidin-4-yl group, an azepan-1-yl group, an azepan-2-yl group, an azepan-3-yl group, an azepan-4-yl group, an imidazolidin-1-yl group, an imidazolidin-2-yl group, an imidazolidin-4-yl group, a piperazin-1-yl group, a piperazin-2-yl group, a pyrazolidin-1-yl group, a pyrazolidin-3-yl group, a pyrazolidin-4-yl group, and a pyrazolidin-5-yl group.

[0020] Preferable embodiments of the partial structure represented by formula (P1) include, but are not limited to, those represented by the following formulas (P1-1) to (P1-3).

[0021]

Chemical formula

[0022] Specific examples of the partial structure represented by formula (P1) include, but are not limited to, those represented by the following formulas (P2-1) to (P2-3).

[0023]

Chemical formula

[0024] The partial structure represented by the above (P1) may be directly bonded to the main chain of the polymer or may be bonded via a spacer group such as an alkylene group, but it is preferably directly bonded to the main chain of the polymer.

[0025] Examples of the form of the above P1 polymer include, but are not limited to, polymers containing repeating units represented by the following formula (C1-1) or (C1-2).

[0026] [Chemical formula] (In the formula, R c1 and R c2 each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, R m represents a hydrogen atom or a methyl group, and n represents a natural number. L, R, T, and * are the same as above.)

[0027] Examples of the alkyl group having 1 to 20 carbon atoms are the same as those exemplified in the description of the above R c1 and R c2 . Among these, as the above R c1 and R c2 , a hydrogen atom and an alkyl group having 1 to 10 carbon atoms are preferable, a hydrogen atom and an alkyl group having 1 to 5 carbon atoms are more preferable, and a methyl group is even more preferable. Also, the above R c1 and R c2 may be the same or different from each other, but it is more preferable that they are the same group.

[0028] Preferable forms of the above P1 polymer include, but are not limited to, those containing repeating units represented by the following formulas (C2-1) to (C2-6).

[0029] [Chemical formula] (In the formula, L, T, R m , n, and * are the same as above.)

[0030] Specific examples of the above P1 polymer include, but are not limited to, those containing repeating units represented by the following formulas (C3-1) to (C3-3).

[0031]

Chemical formula

[0032] The average molecular weight of the above P1 polymer is not particularly limited, but the weight average molecular weight (Mw) is preferably 1,000 to 2,000,000, more preferably 2,000 to 1,000,000. The weight average molecular weight is the value in terms of sodium polystyrene sulfonate by gel permeation chromatography.

[0033] In the present invention, from the viewpoint of improving the dispersibility and aggregation suppression effect of CNT, the side chain represented by the formula (P1) is preferably contained in 10 to 100 mol% of all the repeating units of the P1 polymer, more preferably 30 to 100 mol%, and even more preferably 50 to 100 mol%.

[0034] In the present invention, the P1 polymer may contain, as repeating units other than the repeating unit represented by the formula (P1), repeating units for imparting other functions, as long as the effects of the present invention are not impaired. Examples of such repeating units include repeating units having a crosslinking reactive group that causes a crosslinking reaction with a dispersant, and preferably repeating units represented by the following formula (P3).

[0035]

Chemical formula

[0036] R dExamples include a carboxy group, an aromatic thiol group, a phenol group, etc., with a carboxy group being preferred.

[0037] When the P1 polymer contains a repeating unit represented by the formula (P3), its content is preferably 10 to 70 mol%, more preferably 20 to 70 mol%, and even more preferably 30 to 70 mol% in all the repeating units.

[0038] As repeating units other than the repeating unit represented by another formula (P1), in the polymer containing the repeating unit represented by the formula (C1-1), for example, a repeating unit represented by the following formula (D1) can be mentioned. Also, in the said polymer, as an unreacted site of the copolymer of isobutylene and maleic anhydride as its raw material, it may partly contain a repeating unit represented by the formula (C1-1’) described later. In the polymer containing the repeating unit represented by the formula (C1-2), for example, a repeating unit represented by the following formula (D2) can be mentioned.

[0039]

Chemical formula

[0040] The addition amount of the above P1 polymer varies depending on the solvent used, the substrate used, the required viscosity, the required film shape, etc., but is preferably 10 to 1,000 parts by mass, more preferably 30 to 800 parts by mass, and even more preferably 40 to 500 parts by mass with respect to 100 parts by mass of CNT100 described later. By setting the addition amount of the P1 polymer within the above range, the dispersibility of CNT and the effect of suppressing aggregation can be improved.

[0041] The above P1 polymer can be obtained by polymerizing a monomer obtained by reacting a compound (monomer raw material) having a carboxy group or an acid anhydride group with a compound represented by the following formula (Q1), or by reacting a polymer having a carboxy group or an acid anhydride group in the side chain with a compound represented by the following formula (Q1).

[0042] [Chemical formula] (In the formula, L' represents an amino group or a hydroxy group. R and T are the same as defined above.)

[0043] Preferable embodiments of the compound represented by formula (Q1) include, but are not limited to, those represented by the following formulas (Q1-1) to (Q1-3).

[0044] [Chemical formula] (In the formula, L' and T are the same as defined above.)

[0045] Specific examples of the compound represented by formula (Q1) include, for example, 1-(3-aminopropyl)imidazole, 1-(3-hydroxypropyl)imidazole, N,N-dimethyl-1,3-propanediamine, and N,N-dimethylethanolamine.

[0046] Examples of the above monomer raw materials include maleic anhydride and (meth)acrylic acid.

[0047] Examples of the polymer having a carboxy group or acid anhydride group in the side chain include polymers of maleic anhydride, copolymers of alkenes having 2 to 10 carbon atoms such as isobutylene and maleic anhydride, and polymers of (meth)acrylic acid. In the present invention, a copolymer of isobutylene and maleic anhydride represented by the following formula (C1-1') and a polymer of (meth)acrylic acid represented by the following formula (C1-2') are preferable.

[0048] [Chemical formula] (In the formula, R c1 , R c2 , R m , n and * are the same as defined above.)

[0049] When synthesizing a polymer containing a repeating unit represented by the formula (C3-1) as the above-mentioned P1 polymer, for example, the method shown in the following Scheme 1 can be mentioned.

[0050]

Chemical formula

[0051] In Scheme 1, after reacting a copolymer (C1-1’) of isobutylene and maleic anhydride with N,N-dimethyl-1,3-propanediamine, the obtained reaction solution is stirred for a predetermined time in the presence of ammonia, whereby a polymer containing a repeating unit represented by the formula (C3-1) can be synthesized. Note that as the copolymer (C1-1’) of isobutylene and maleic anhydride, commercially available products can be used, for example, Isoban series (manufactured by Kuraray Co., Ltd.: trade name).

[0052] The solvent used in the above reaction is not particularly limited as long as it can disperse or dissolve the raw materials to be used. Examples of such solvents include dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone (NMP), hexamethylphosphoric triamide, acetonitrile, acetone, alcohols (such as methanol, ethanol, 1-propanol, 2-propanol, etc.), glycols (such as ethylene glycol, triethylene glycol, etc.), cellosolves (such as ethyl cellosolve, methyl cellosolve, etc.), polyhydric alcohols (such as glycerin, pentaerythritol, etc.), tetrahydrofuran, toluene, ethyl acetate, butyl acetate, benzene, toluene, xylene, pentane, hexane, heptane, chlorobenzene, dichlorobenzene, trichlorobenzene, hexadecane, benzyl alcohol, and oleylamine, etc. Among these, from the viewpoints of reaction temperature and reaction concentration, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone are preferred. These solvents may be appropriately selected according to the raw materials to be used. The above solvents may be used alone or in combination of two or more.

[0053] In the above reaction, the mixing ratio of the polymer (C1-1’) and N,N-dimethyl-1,3-propanediamine is preferably such that all of the acid anhydride groups in the polymer (C1-1’) can react with N,N-dimethyl-1,3-propanediamine. Preferably, 1 to 3 moles of N,N-dimethyl-1,3-propanediamine are used per mole of the repeating unit of the polymer (C1-1’), and more preferably 1 to 2 moles.

[0054] The reaction temperature of the above reaction is usually 40 to 200 °C. The reaction time is variously selected depending on the reaction temperature, but is usually about 30 minutes to 50 hours.

[0055] The obtained polymer may be used as the reaction solution as it is, or after dilution or concentration, or after the polymer is isolated by appropriate means and then dissolved in an appropriate solvent. Examples of the above solvent include the solvents described above.

[0056] When synthesizing a polymer containing a repeating unit represented by the formula (C3-3) as the above polymer, for example, the method shown in the following Scheme 2 can be mentioned.

[0057]

Chemical formula

[0058] In Scheme 2, first, monomer (C3-3’) is synthesized by esterifying (meth)acrylic acid and N,N-dimethylethanolamine (the first step). Then, the obtained monomer (C3-3’) is polymerized in a solution (the second step), whereby a polymer containing a repeating unit represented by the formula (C3-3) can be synthesized. When a commercially available product can be obtained as the monomer (C3-3’), the commercially available product may be used as it is and the process may be carried out from the second step.

[0059] The solvent used in the reaction of the above first step is not particularly limited as long as it can disperse or dissolve the raw materials used. Examples of such solvents include the same ones as those mentioned in Scheme 1 above, and they may be appropriately selected according to the raw materials used. The above solvent may be used alone or in a mixture of two or more.

[0060] In the above reaction, an acid or a base can be used as a catalyst. Specific examples include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; organic carboxylic acids such as acetic acid, propionic acid, phthalic acid, and benzoic acid; organic sulfonic acids such as methylsulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid; hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide, and magnesium hydroxide; carbonates and hydrogen carbonates of alkali metals or alkaline earth metals such as sodium hydrogen carbonate, potassium carbonate, and calcium hydrogen carbonate, etc.

[0061] In the second step, the monomer (C3-3’) obtained in the first step is polymerized in a solvent. The polymerization method is not particularly limited and can be appropriately selected from the polymerization methods commonly used in the polymerization of acrylic polymers. Examples of the polymerization method include solution polymerization method, emulsion polymerization method, suspension polymerization method, etc. Further, an initiator may be used during the polymerization. As the initiator, commercially available products can be used. For example, AIBN, VE-073, V-70, V-65, V-601, V-59, V-40, Vm-110, VA-044, V-046B, V-50, VA-057, VA-061, VA-086, V-501 (all manufactured by Fujifilm Wako Pure Chemical Corporation) can be mentioned.

[0062] The obtained polymer may be used as the reaction solution as it is, or after dilution or concentration, or after the polymer is isolated by appropriate means and then dissolved in an appropriate solvent. Examples of the above solvent include the solvents described above.

[0063] CNT is generally produced by an arc discharge method, a chemical vapor deposition method (CVD method), a laser ablation method, etc. However, the CNT used in the present invention may be obtained by any method. Further, CNT includes single-walled CNT (hereinafter also abbreviated as SWCNT) in which a single carbon film (graphene sheet) is wound cylindrically, double-walled CNT (hereinafter also abbreviated as DWCNT) in which two graphene sheets are wound concentrically, and multi-walled CNT (MWCNT) in which a plurality of graphene sheets are wound concentrically. In the present invention, SWCNT, DWCNT, and MWCNT can be used alone or in combination of a plurality thereof.

[0064] In addition, when producing SWCNT, DWCNT, or MWCNT by the above method, catalyst metals such as nickel, iron, cobalt, and yttrium may remain, so purification may be required to remove these impurities. For impurity removal, acid treatment with nitric acid, sulfuric acid, etc. along with ultrasonic treatment is effective. However, in acid treatment with nitric acid, sulfuric acid, etc., the π-conjugated system constituting the CNT may be destroyed, and the original properties of the CNT may be impaired. Therefore, it is desirable to purify and use under appropriate conditions.

[0065] Specific examples of CNTs that can be used in the present invention include Sparkloas CNT [manufactured by the National Institute of Advanced Industrial Science and Technology], eDIPS-CNT [manufactured by the National Institute of Advanced Industrial Science and Technology], SWNT series [manufactured by Meisho Nanocarbon Co., Ltd.: trade name], VGCF series [manufactured by Showa Denko K.K.: trade name], FloTube series [manufactured by CNano Technology: trade name], AMC [manufactured by Ube Industries, Ltd.: trade name], NANOCYL NC7000 series [manufactured by Nanocyl S.A.: trade name], Baytubes [manufactured by Bayer: trade name], GRAPHISTRENGTH [manufactured by Arkema: trade name], MWNT7 [manufactured by Hodogaya Chemical Co., Ltd.: trade name], Hyperion CNT [manufactured by Hypeprion Catalysis International: trade name], TC series [manufactured by Toda Kogyo Corporation: trade name], Flo Tube series [manufactured by Jiangsu Cnano Technology: trade name], and the like.

[0066] As the dispersant, it can be appropriately selected from those conventionally used as dispersants for conductive carbon materials such as CNTs. For example, carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), acrylic resin emulsion, water-soluble acrylic polymer, styrene emulsion, silicone emulsion, acrylic silicone emulsion, fluororesin emulsion, EVA emulsion, vinyl acetate emulsion, vinyl chloride emulsion, urethane resin emulsion, the triarylamine-based highly branched polymer described in International Publication No. 2014 / 042080, the polymer having an oxazoline group in the side chain described in International Publication No. 2015 / 029949, etc. can be mentioned. In the present invention, it is preferable to use a dispersant containing the polymer having an oxazoline group in the side chain described in International Publication No. 2015 / 029949 or a dispersant containing the triarylamine-based highly branched polymer described in International Publication No. 2014 / 042080.

[0067] As the polymer having an oxazoline group in the side chain (hereinafter referred to as oxazoline polymer), a vinyl-based polymer having a repeating unit bonded to the polymer main chain or a spacer group at the 2-position of the oxazoline ring, which is obtained by radical polymerization of an oxazoline monomer having a polymerizable carbon-carbon double bond-containing group at the 2-position as shown in the formula (1), is preferable.

[0068]

Chemical formula

[0069] In the above, X represents a polymerizable carbon-carbon double bond-containing group, and R 1 ~R 4 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms.

[0070] As the polymerizable carbon-carbon double bond-containing group of the oxazoline monomer, there is no particular limitation as long as it contains a polymerizable carbon-carbon double bond, but a chain hydrocarbon group containing a polymerizable carbon-carbon double bond is preferred. For example, alkenyl groups having 2 to 8 carbon atoms such as vinyl group, allyl group, and isopropenyl group are preferred. Examples of the halogen atom include fluorine atom, chlorine atom, bromine atom, and iodine atom. The alkyl group having 1 to 5 carbon atoms may be linear, branched, or cyclic. For example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, cyclohexyl group, etc. may be mentioned. Examples of the aryl group having 6 to 20 carbon atoms include phenyl group, xylyl group, tolyl group, biphenyl group, naphthyl group, etc. Examples of the aralkyl group having 7 to 20 carbon atoms include benzyl group, phenylethyl group, phenylcyclohexyl group, etc.

[0071] Examples of the oxazoline monomer having a polymerizable carbon-carbon double bond-containing group at the 2-position represented by the formula (1) include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-4-ethyl-2-oxazoline, 2-vinyl-4-propyl-2-oxazoline, 2-vinyl-4-butyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-vinyl-5-ethyl-2-oxazoline, 2-vinyl-5-propyl-2-oxazoline, 2-vinyl-5-butyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-4-ethyl-2-oxazoline, 2-isopropenyl-4-propyl-2-oxazoline, 2-isopropenyl-4-butyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2-isopropenyl-5-propyl-2-oxazoline, 2-isopropenyl-5-butyl-2-oxazoline, etc. From the viewpoint of easy availability, etc., 2-isopropenyl-2-oxazoline is preferred.

[0072] Also, considering the preparation of the dispersion using an aqueous solvent, the oxazoline polymer is preferably also water-soluble. Such a water-soluble oxazoline polymer may be a homopolymer of the oxazoline monomer represented by the above formula (1), but in order to further enhance the solubility in water, it is preferably obtained by radical polymerization of at least two monomers, namely the above oxazoline monomer and a (meth)acrylic acid ester monomer having a hydrophilic functional group.

[0073] Examples of the (meth)acrylic monomer having a hydrophilic functional group include (meth)acrylic acid, 2-hydroxyethyl acrylate, methoxypolyethylene glycol acrylate, monoesterified product of acrylic acid and polyethylene glycol, 2-aminoethyl acrylate and its salts, 2-hydroxyethyl methacrylate, methoxypolyethylene glycol methacrylate, monoesterified product of methacrylic acid and polyethylene glycol, 2-aminoethyl methacrylate and its salts, sodium (meth)acrylate, ammonium (meth)acrylate, (meth)acrylonitrile, (meth)acrylamide, N-methylol(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, sodium styrenesulfonate, etc. These may be used alone or in combination of two or more. Among these, methoxypolyethylene glycol (meth)acrylate and monoesterified product of (meth)acrylic acid and polyethylene glycol are preferred.

[0074] Also, other monomers other than the above oxazoline monomer and the (meth)acrylic monomer having a hydrophilic functional group can be used in combination as long as they do not adversely affect the CNT dispersibility of the oxazoline polymer. Examples of other monomers include (meth)acrylic acid ester monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, perfluoroethyl (meth)acrylate, and phenyl (meth)acrylate; olefin monomers such as ethylene, propylene, butene, and pentene; haloolefin monomers such as vinyl chloride, vinylidene chloride, and vinyl fluoride; styrene monomers such as styrene and α-methylstyrene; carboxylic acid vinyl ester monomers such as vinyl acetate and vinyl propionate; vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether. These can be used alone or in combination of two or more.

[0075] In the monomer component used for the production of the oxazoline polymer used in the present invention, the content of the oxazoline monomer is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more from the viewpoint of further enhancing the CNT dispersibility of the obtained oxazoline polymer. The upper limit of the content of the oxazoline monomer in the monomer component is 100% by mass. In this case, a homopolymer of the oxazoline monomer is obtained. On the other hand, from the viewpoint of further enhancing the water solubility of the obtained oxazoline polymer, the content of the (meth)acrylic monomer having a hydrophilic functional group in the monomer component is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. Also, the content of other monomers in the monomer component is within a range that does not affect the CNT dispersibility of the obtained oxazoline polymer as described above, and since it varies depending on the type, it cannot be determined unconditionally. However, it may be appropriately set preferably in the range of 5 to 95% by mass, more preferably 10 to 90% by mass.

[0076] The average molecular weight of the oxazoline polymer is not particularly limited, but the weight average molecular weight is preferably from 1,000 to 2,000,000, more preferably from 2,000 to 1,000,000. The weight average molecular weight is a polystyrene equivalent value determined by gel permeation chromatography.

[0077] The oxazoline polymer that can be used in the present invention can be synthesized from the above monomers by a conventionally known radical polymerization, but can also be obtained as a commercially available product. Examples of such commercially available products include Epocros WS-300 (manufactured by Nippon Shokubai Co., Ltd., solid content concentration 10% by mass, aqueous solution), Epocros WS-700 (manufactured by Nippon Shokubai Co., Ltd., solid content concentration 25% by mass, aqueous solution), Epocros WS-500 (manufactured by Nippon Shokubai Co., Ltd., solid content concentration 39% by mass, water / 1-methoxy-2-propanol solution), Poly(2-ethyl-2-oxazoline) (Aldrich), Poly(2-ethyl-2-oxazoline) (Alfa Aesar), Poly(2-ethyl-2-oxazoline) (VWR International, LLC), and the like. When commercially available as a solution, it may be used as it is or after substitution with the target solvent.

[0078] Also, triarylamine-based highly branched polymers obtained by condensation polymerization of triarylamines and aldehydes and / or ketones represented by the following formulas (2) and (3) under acidic conditions are also preferably used.

[0079] [Chemical formula]

[0080] In the above formulas (2) and (3), Ar 1 ~Ar 3 each independently represents any divalent organic group represented by formulas (4) to (8), and in particular, a substituted or unsubstituted phenylene group represented by formula (4) is preferred.

[0081] [Chemical formula]

[0082] Also, in formulas (2) and (3), Z 1 and Z 2 each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms, or any monovalent organic group represented by formulas (9) to (12) (however, Z 1 and Z 2 will not simultaneously be the above alkyl group.).

[0083] [Chemical formula]

[0084] In the above formulas (3) to (8), R 101 ~R 138 each independently represents a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched alkoxy group having 1 to 5 carbon atoms, or a carboxyl group, a sulfo group, a phosphoric acid group, a phosphonic acid group, or a salt thereof.

[0085] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0086] Examples of the linear or branched alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, and the like.

[0087] Examples of the linear or branched alkoxy group having 1 to 5 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, and the like.

[0088] Examples of salts of carboxyl group, sulfo group, phosphoric acid group and phosphonic acid group include alkali metal salts such as sodium and potassium; alkaline earth metal salts such as magnesium and calcium; ammonium salts; aliphatic amine salts such as propylamine, dimethylamine, triethylamine and ethylenediamine; alicyclic amine salts such as imidazoline, piperazine and morpholine; aromatic amine salts such as aniline and diphenylamine; pyridinium salts and the like.

[0089] In the above formulas (9) to (12), R 139 ~R 162 are each independently a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched haloalkyl group having 1 to 5 carbon atoms, a phenyl group, OR 163 、COR 163 、NR 163 R 164 、COOR 165 (In these formulas, R 163 and R 164 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched haloalkyl group having 1 to 5 carbon atoms, or a phenyl group, and R 165 represents a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched haloalkyl group having 1 to 5 carbon atoms, or a phenyl group.), or represents a carboxyl group, a sulfo group, a phosphoric acid group, a phosphonic acid group or a salt thereof.

[0090] Here, examples of the linear or branched haloalkyl group having 1 to 5 carbon atoms include difluoromethyl group, trifluoromethyl group, bromodifluoromethyl group, 2-chloroethyl group, 2-bromoethyl group, 1,1-difluoroethyl group, 2,2,2-trifluoroethyl group, 1,1,2,2-tetrafluoroethyl group, 2-chloro-1,1,2-trifluoroethyl group, pentafluoroethyl group, 3-bromopropyl group, 2,2,3,3-tetrafluoropropyl group, 1,1,2,3,3,3-hexafluoropropyl group, 1,1,1,3,3,3-hexafluoropropan-2-yl group, 3-bromo-2-methylpropyl group, 4-bromobutyl group, perfluoropentyl group, and the like. In addition, examples of the halogen atom and the linear or branched alkyl group having 1 to 5 carbon atoms include the same groups as those exemplified in the above formulas (3) to (8).

[0091] Z 1 and Z 2 are each independently preferably a hydrogen atom, 2- or 3-thienyl group, or a group represented by formula (9). In particular, when 1 either one of Z 2 and Z 141 is a hydrogen atom and the other is a hydrogen atom, 2- or 3-thienyl group, or a group represented by formula (9), especially when R 141 is a phenyl group or R is a methoxy group, it is more preferable. 141 When R is a phenyl group, in the method for introducing an acidic group described later, when a method for introducing an acidic group after polymer production is used, an acidic group may be introduced onto this phenyl group.

[0092]

[0093] Examples of the aldehyde compound used in the production of the above highly branched polymer include saturated aliphatic aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde, propyl aldehyde, butyl aldehyde, isobutyl aldehyde, valeraldehyde, caproaldehyde, 2-methylbutyl aldehyde, hexyl aldehyde, undecyl aldehyde, 7-methoxy-3,7-dimethyloctyl aldehyde, cyclohexanecarboxyaldehyde, 3-methyl-2-butyl aldehyde, glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, adipinaldehyde; unsaturated aliphatic aldehydes such as acrolein, methacrolein; heterocyclic aldehydes such as furfural, pyridine aldehyde, thiophene aldehyde; aromatic aldehydes such as benzaldehyde, tolyl aldehyde, trifluoromethylbenzaldehyde, phenylbenzaldehyde, salicylaldehyde, anisaldehyde, acetoxybenzaldehyde, terephthalaldehyde, acetylbenzaldehyde, formylbenzoic acid, methyl formylbenzoate, aminobenzaldehyde, N,N-dimethylaminobenzaldehyde, N,N-diphenylaminobenzaldehyde, naphthyl aldehyde, anthryl aldehyde, phenanthryl aldehyde; aralkyl aldehydes such as phenylacetaldehyde, 3-phenylpropionaldehyde, etc. Among them, it is preferable to use aromatic aldehydes.

[0094] In addition, examples of the ketone compound used in the production of the above highly branched polymer include alkyl aryl ketones and diaryl ketones, such as acetophenone, propiophenone, diphenyl ketone, phenyl naphthyl ketone, dinaphthyl ketone, phenyl tolyl ketone, ditolyl ketone, etc.

[0095] The highly branched polymer used in the present invention can be produced, for example, according to the method described in International Publication No. 2014 / 042080.

[0096] The average molecular weight of the above-mentioned highly branched polymer is not particularly limited, but the weight average molecular weight is preferably from 1,000 to 2,000,000, more preferably from 2,000 to 1,000,000.

[0097] Specific examples of the highly branched polymer include, but are not limited to, those represented by the following formula.

Chemical formula

[0098] In the present invention, the mixing ratio of CNT and the dispersant can be about 1,000:1 to 1:100 by mass ratio. In addition, the addition amount of the above-mentioned dispersant is not particularly limited as long as it can disperse CNT in the solvent, but it is preferably 5 to 700 parts by mass, more preferably 10 to 500 parts by mass, and even more preferably 20 to 300 parts by mass with respect to 100 parts by mass of CNT.

[0099] The dispersion liquid of the present invention may contain a cross-linking agent that causes a cross-linking reaction with the dispersant used or a cross-linking agent that self-cross-links, as long as the effects of the present invention are not impaired. These cross-linking agents are preferably soluble in the solvent used.

[0100] Examples of the cross-linking agent for the triarylamine-based highly branched polymer include melamine-based, substituted urea-based, or their polymer-based cross-linking agents, etc. These cross-linking agents can be used alone or in combination of two or more. Preferably, it is a cross-linking agent having at least two cross-linking-forming substituents, and examples include compounds such as CYMEL (registered trademark), methoxymethylated glycoluril, butoxymethylated glycoluril, methylolated glycoluril, methoxymethylated melamine, butoxymethylated melamine, methylolated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methylolated benzoguanamine, methoxymethylated urea, butoxymethylated urea, methylolated urea, methoxymethylated thiourea, methoxymethylated thiourea, methylolated thiourea, etc., and condensates of these compounds.

[0101] As a crosslinking agent for the oxazoline polymer, for example, any compound having two or more functional groups reactive with an oxazoline group such as a carboxyl group, a hydroxyl group, a thiol group, an amino group, a sulfinic acid group, and an epoxy group is not particularly limited, but a compound having two or more carboxyl groups is preferable. In addition, a compound having a functional group that generates the above functional group during heating during film formation or in the presence of an acid catalyst and causes a crosslinking reaction, for example, a sodium salt, potassium salt, lithium salt, ammonium salt, etc. of carboxylic acid can also be used as a crosslinking agent.

[0102] Specific examples of the compound that undergoes a crosslinking reaction with an oxazoline group include synthetic polymers such as polyacrylic acid and its copolymers, and metal salts of natural polymers such as carboxymethyl cellulose and alginic acid, which exhibit crosslinking reactivity in the presence of an acid catalyst, and ammonium salts of the above synthetic polymers and natural polymers, which exhibit crosslinking reactivity by heating. In particular, sodium polyacrylate, lithium polyacrylate, ammonium polyacrylate, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, ammonium carboxymethyl cellulose, etc., which exhibit crosslinking reactivity in the presence of an acid catalyst or under heating conditions, are preferable.

[0103] Such a compound that undergoes a crosslinking reaction with an oxazoline group can also be obtained as a commercial product. Examples of such commercial products include sodium polyacrylate (manufactured by Fujifilm Wako Pure Chemical Corporation, degree of polymerization 2,700 to 7,500), sodium carboxymethyl cellulose (manufactured by Fujifilm Wako Pure Chemical Corporation), sodium alginate (manufactured by Kanto Chemical Co., Inc., deer grade 1), Aron A-30 (ammonium polyacrylate, manufactured by Toagosei Co., Ltd., solid content concentration 32% by mass, aqueous solution), DN-800H (ammonium carboxymethyl cellulose, manufactured by Daicel Finechem Ltd.), ammonium alginate (manufactured by Kimica Corporation), etc.

[0104] Examples of self-crosslinking crosslinking agents include compounds having crosslinkable functional groups that react with each other, such as aldehyde groups, epoxy groups, vinyl groups, isocyanate groups, alkoxy groups, and carboxyl groups with respect to hydroxyl groups, aldehyde groups, amino groups, isocyanate groups, epoxy groups, and aldehyde groups with respect to amino groups, within the same molecule, and compounds having hydroxyl groups (dehydration condensation), mercapto groups (disulfide bonds), ester groups (Claisen condensation), silanol groups (dehydration condensation), vinyl groups, acrylic groups, etc. that react with the same crosslinkable functional groups.

[0105] Specific examples of self-crosslinking crosslinking agents include polyfunctional acrylates that exhibit crosslinking reactivity in the presence of an acid catalyst, tetraalkoxysilanes, monomers having blocked isocyanate groups, and block copolymers of monomers having at least one of hydroxyl groups, carboxylic acids, and amino groups.

[0106] Such self-crosslinking crosslinking agents can also be obtained as commercial products. Examples of such commercial products include, for polyfunctional acrylates, A-9300 (triacrylate of ethoxylated isocyanuric acid, manufactured by Shin-Nakamura Chemical Co., Ltd.), A-GLY-9E (Ethoxylated glycerine triacrylate (EO9mol), manufactured by Shin-Nakamura Chemical Co., Ltd.), A-TMMT (pentaerythritol tetraacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.); for tetraalkoxysilanes, tetramethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), tetraethoxysilane (manufactured by Toei Chemical Industry Co., Ltd.); and for polymers having blocked isocyanate groups, Elastron series E-37, H-3, H38, BAP, NEW BAP-15, C-52, F-29, W-11P, MF-9, MF-25K (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), etc.

[0107] When adding a crosslinking agent, the amount added varies depending on the solvent used, the substrate used, the required viscosity, the required film shape, etc., but is preferably 5 to 1,000 parts by mass, more preferably 10 to 800 parts by mass, and even more preferably 20 to 500 parts by mass with respect to 100 parts by mass of CNT. These crosslinking agents may cause a crosslinking reaction by self-condensation, but they cause a crosslinking reaction with the dispersant. When crosslinkable substituents are present in the dispersant, the crosslinking reaction is promoted by these crosslinkable substituents.

[0108] The solvent used for preparing the dispersion of the present invention is not particularly limited, and examples include water or a hydrophilic solvent. A hydrophilic solvent is an organic solvent that is arbitrarily mixed with water. For example, ethers such as tetrahydrofuran (THF); amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP); ketones such as acetone; alcohols such as methanol, ethanol, n-propanol, and isopropanol; glycol ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether; and organic solvents such as glycols such as ethylene glycol and propylene glycol. These solvents can be used alone or in combination of two or more. In particular, from the viewpoint of improving the proportion of isolated dispersion of CNT, water, NMP, DMF, THF, methanol, ethanol, n-propanol, isopropanol, n-butanol, and t-butanol are preferable. Also, from the viewpoint of improving coatability, it is preferable to contain methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butanol, and ethylene glycol monobutyl ether. Also, from the viewpoint of reducing costs, it is preferable to contain water. These solvents can be used alone or in combination of two or more for the purpose of increasing the proportion of isolated dispersion, improving coatability, and reducing costs.

[0109] A polymer serving as a matrix may be added to the dispersion of the present invention. Examples of the matrix polymer include fluororesins such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer [P(VDF-HFP)], vinylidene fluoride-chloro trifluoroethylene copolymer [P(VDF-CTFE)]; polyolefin resins such as polyvinylpyrrolidone, ethylene-propylene-diene terpolymer, PE (polyethylene), PP (polypropylene), EVA (ethylene-vinyl acetate copolymer), EEA (ethylene-ethyl acrylate copolymer); polystyrene resins such as PS (polystyrene), HIPS (high impact polystyrene), AS (acrylonitrile-styrene copolymer), ABS (acrylonitrile-butadiene-styrene copolymer), MS (methyl methacrylate-styrene copolymer), styrene-butadiene rubber; polycarbonate resin; vinyl chloride resin; polyamide resin; polyimide resin; (meth)acrylic resins such as sodium polyacrylate, PMMA (polymethyl methacrylate); polyester resins such as PET (polyethylene terephthalate), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, PLA (polylactic acid), poly-3-hydroxybutyric acid, polycaprolactone, polybutylene succinate, polyethylene succinate / adipate; polyphenylene ether resin; modified polyphenylene ether resin; polyacetal resin; polysulfone resin; polyphenylene sulfide resin; polyvinyl alcohol resin; polyglycolic acid; modified starch; cellulose acetate, carboxymethyl cellulose, cellulose triacetate; chitin, chitosan; lignin and other thermoplastic resins, as well as conductive polymers such as polyaniline and its semi-oxidized form, emeraldine base; polythiophene; polypyrrole; polyphenylene vinylene; polyphenylene; polyacetylene, and furthermore, thermosetting resins and photocurable resins such as epoxy resin; urethane acrylate; phenol resin; melamine resin; urea resin; alkyd resin, etc.Among these, in the dispersion of the present invention, since it is preferable to use water as the solvent, water-soluble polymers can be used as the matrix polymer. For example, sodium polyacrylate, sodium carboxymethyl cellulose, water-soluble cellulose ether, sodium alginate, polyvinyl alcohol, polystyrene sulfonic acid, polyethylene glycol, etc. can be mentioned. In particular, sodium polyacrylate, sodium carboxymethyl cellulose, etc. are preferable.

[0110] The matrix polymer can also be obtained as a commercial product. Such commercial products include, for example, sodium polyacrylate (manufactured by Fujifilm Wako Pure Chemical Corporation, degree of polymerization 2,700 - 7,500), sodium carboxymethyl cellulose (manufactured by Fujifilm Wako Pure Chemical Corporation), sodium alginate (manufactured by Kanto Chemical Co., Inc., deer grade 1), Methocel SH series (hydroxypropyl methyl cellulose, manufactured by Shin-Etsu Chemical Co., Ltd.), Methocel SE series (hydroxyethyl methyl cellulose, manufactured by Shin-Etsu Chemical Co., Ltd.), JC-25 (fully saponified polyvinyl alcohol, manufactured by Nippon Vinylon K.K.), JM-17 (intermediate saponified polyvinyl alcohol, manufactured by Nippon Vinylon K.K.), JP-03 (partially saponified polyvinyl alcohol, manufactured by Nippon Vinylon K.K.), polystyrene sulfonic acid (manufactured by Aldrich, solid content concentration 18% by mass, aqueous solution), etc.

[0111] When adding the matrix polymer, the addition amount is not particularly limited, but it is preferably about 0.0001 - 99% by mass, and more preferably about 0.001 - 90% by mass in the dispersion.

[0112] The method for preparing the dispersion of the present invention is not particularly limited. However, the CNT, dispersant, solvent, P1 polymer, and optionally used matrix polymer, etc. may be mixed in any order to prepare the dispersion. At this time, if there is a concern that the P1 polymer has a crosslinking reactive group such as a carboxy group and an unintended crosslinking reaction may occur between this crosslinking reactive group and the dispersant, a part or all of the above crosslinking reactive groups may be neutralized with a base such as ammonia. Further, it is preferable to perform a dispersion treatment on the mixture, and by this treatment, the dispersion ratio of the CNT can be further improved. Examples of the dispersion treatment include wet treatments using mechanical treatments such as ball mills, bead mills, and jet mills, and ultrasonic treatments using bath-type or probe-type sonicator. In particular, wet treatments using jet mills and ultrasonic treatments are preferable.

[0113] The time for the dispersion treatment is arbitrary, but it is preferably about 1 minute to 10 hours, and more preferably about 5 minutes to 5 hours. At this time, a heat treatment may be performed as necessary.

[0114] In addition, when using optional components such as matrix polymers, etc., these may be added after preparing a mixture composed of CNT, dispersant, and solvent.

[0115] In the present invention, the solid content concentration of the dispersion is not particularly limited. However, considering forming an undercoat layer with a desired basis weight and film thickness, it is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and still more preferably 5% by mass or less. Further, the lower limit is arbitrary, but from a practical point of view, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. Note that the solid content is the total amount of components other than the solvent constituting the dispersion.

[0116] The dispersion of the present invention can be applied and formed into a film on a suitable substrate such as PET, glass, ITO, etc. by an appropriate method such as spin coating method, dip coating method, flow coating method, inkjet method, spray method, bar coating method, gravure coating method, slit coating method, roll coating method, transfer printing method, brush coating, blade coating method, air knife coating method, etc. The obtained thin film can be suitably used for an antistatic film utilizing the metallic properties of CNTs, a conductive material such as a transparent electrode, or a photoelectric conversion element, a thermoelectric conversion element, an electroluminescent element, etc. that utilize the semiconductor properties.

Examples

[0117] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples. The apparatuses used are as follows. (1) Probe-type ultrasonic irradiation apparatus Manufactured by Hielscher Ultrasonics, UIP1000 (2) Particle size distribution analyzer Manufactured by Horiba, Ltd., Laser diffraction / scattering type particle size distribution measuring apparatus LA-960 〈Measurement conditions〉 Measurement cell: Flow cell Refractive index of measurement solvent: 1.333 - 0.000i (ion-exchanged water) Refractive index of solute: 1.920 - 0.522i (carbon) Ultrasonic wave: Non-irradiated (3) Constant temperature bath DDRV422C VACUUM DRYING OVEN manufactured by ADVANTEC (4) Size exclusion chromatography (SEC) (estimation of weight average molecular weight) High performance liquid chromatograph Prominence manufactured by Shimadzu Corporation Eluent: 5 mM sodium tetraborate decahydrate (pH 9.3) Column: TSK gel α6000 manufactured by Tosoh Corporation + TSK gel α4000 manufactured by Tosoh Corporation Column temperature: 40 °C Detector: UV (210 nm) Flow rate: 0.5 mL / min Sample concentration: 0.1% (10 μL injection)

[0118] [1] Synthesis of P1 polymer [Synthesis Example 1] Synthesis of Compound A 4.48 g (52.0 mmol) of methacrylic acid (manufactured by Junsei Chemical Co., Ltd.), 10.0 g (63.6 mmol) of dimethylaminoethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.012 g (0.038 mmol) of VE-073 (manufactured by Fujifilm Wako Pure Chemical Corporation) as an initiator were dissolved in 82.12 g of ethanol (manufactured by Junsei Chemical Co., Ltd.). After replacing the inside of the system with nitrogen gas, the internal temperature was raised to 80 °C and heated with stirring for 5 hours. The reaction solution was cooled and dropped into 500 g of hexane, and the formed precipitate was filtered off. The obtained filtrate was dispersed again in 100 g of ethanol and dropped into 500 g of hexane (manufactured by Junsei Chemical Co., Ltd.). The formed precipitate was filtered off, and then the obtained filtrate was dried under reduced pressure at 60 °C for 6 hours to obtain white Compound A (yield: 6.53 g, yield: 45.0%). The Mw of the obtained P1 polymer was 1.45×10 5 (in terms of sodium polystyrene sulfonate).

[0119] [2] Preparation of carbon nanotube dispersion [Production Example 1] Preparation of Dispersion A 0.5 g (100 parts by mass) of FloTube 6121 (manufactured by Jiangsu Cnano Technology Co., Ltd., multi-walled CNT) as CNT, 5.0 g (100 parts by mass) of WS-300 (manufactured by Nippon Shokubai Co., Ltd., an aqueous solution containing oxazoline polymer, solid content concentration: 10.0% by mass), 37.15 g of pure water, and 7.35 g of 2-propanol (manufactured by Junsei Chemical Co., Ltd., reagent grade) were mixed. The obtained mixture was subjected to ultrasonic treatment for 30 minutes using a probe-type ultrasonic irradiation device to prepare Dispersion A in which CNT was uniformly dispersed.

[0120] [Example 1] 200 parts by mass of Compound A, pure water, 2-propanol (reagent grade, manufactured by Junsei Chemical Co., Ltd.), and 200 parts by mass of ammonia (666.67 parts by mass as 30% aqueous ammonia) were mixed. The mixed solution was added to Dispersion A to prepare Dispersion 1 with a solid content concentration of 1% by mass. At this time, the final mixing ratio of the solvents was pure water:2-propanol = 92:8 (mass ratio). Dispersion 1 was a black ink in which CNTs were uniformly dispersed.

[0121] [Example 2] 200 parts by mass of Compound A, pure water, 2-propanol (reagent grade, manufactured by Junsei Chemical Co., Ltd.), and 10 parts by mass of ammonia (33.33 parts by mass as 30% aqueous ammonia) were mixed. The mixed solution was added to Dispersion A to prepare Dispersion Composition B with a solid content concentration of 1% by mass. At this time, the final mixing ratio of the solvents was pure water:2-propanol = 92:8 (mass ratio). Dispersion 2 was a black ink in which CNTs were uniformly dispersed.

[0122] [Comparative Example 1] The Dispersion A prepared in Production Example 1 was used as Dispersion C1 as it was.

[0123] [Comparative Example 2] 76 parts by mass of Aron A-30, pure water, and 2-propanol (reagent grade, manufactured by Junsei Chemical Co., Ltd.) were mixed with Dispersion A to prepare Dispersion C2 with a solid content concentration of 1.38% by mass. At this time, the final mixing ratio of the solvents was pure water:2-propanol = 85:15 (mass ratio). Dispersion C2 was a black ink in which CNTs were uniformly dispersed.

[0124] [Comparative Example 3] 76 parts by mass of Aron A-30, pure water, and 2-propanol (reagent grade, manufactured by Junsei Chemical Co., Ltd.) were mixed with Dispersion A to prepare Dispersion C3 with a solid content concentration of 1.00% by mass. At this time, the final mixing ratio of the solvents was pure water:2-propanol = 85:15 (mass ratio). Dispersion C3 was a black ink in which CNTs were uniformly dispersed.

[0125] The compositions of Dispersions 1, 2 and C1 - C3 were summarized in Table 1.

[0126] Regarding the obtained dispersions, the particle size distributions (median diameters d 50 and d 90 ) were measured using a particle size distribution analyzer immediately after preparation (before storage) and after storage under heating conditions for 1 day. The results are shown in Table 1. The heating of the dispersion was carried out by putting the dispersion into a 50 - ml poly bottle, placing it in a constant - temperature bath heated to 50°C and leaving it standing for 1 day. Then, the dispersion was taken out of the constant - temperature bath, cooled to room temperature, and then used for the measurement of the particle size distribution. In the present invention, room temperature means 23°C ± 5°C, preferably 23°C.

[0127]

Table 1

[0128] From the results shown in Table 1, the following were confirmed. In the dispersions of Examples 1 and 2, it was confirmed that immediately after preparation, the particle size of CNTs was small and good dispersibility was ensured. And after storage, since the particle size of CNTs hardly changed compared with that before storage, it was confirmed that the dispersion state of CNTs did not change and a good dispersion state was maintained. In the dispersion of Comparative Example 1, it was confirmed that immediately after preparation, the particle size of CNTs was larger than that in the examples and the dispersibility of CNTs was inferior. Furthermore, after storage, CNTs aggregated and lost fluidity, and the state where the particle size distribution could not be measured was reached. From these results, it was confirmed that the dispersion of Comparative Example 1 was more likely to change the dispersion state of CNTs compared with the dispersions of the examples and was inferior in the aggregation - suppression effect. In the dispersions of Comparative Examples 2 and 3, it was confirmed that immediately after preparation, the particle size of CNTs was small and good dispersibility was obtained, but after storage, the particle size of CNTs increased and aggregation was confirmed. From these results, it was confirmed that the dispersions of Comparative Examples 2 and 3 were more likely to change the dispersion state of CNTs compared with the dispersions of the examples and were inferior in the aggregation - suppression effect.

Claims

1. A carbon nanotube dispersion liquid containing a carbon nanotube, a dispersant, a solvent, and a polymer having a partial structure represented by the following formula (P1) in a side chain, wherein the dispersant contains a polymer having an oxazoline group in a side chain. 【Chemical Formula 1】 (In the formula, L represents -O- or -NH-, R represents an alkylene group having 1 to 20 carbon atoms, T represents a substituted or unsubstituted amino group, a nitrogen-containing heteroaryl group having 2 to 20 carbon atoms, or a nitrogen-containing aliphatic heterocyclic group having 2 to 20 carbon atoms, and * represents a bond.)

2. The carbon nanotube dispersion liquid according to Claim 1, wherein the partial structure represented by the formula (P1) is represented by any one of the following formulas (P1-1) to (P1-3). [Chemical Formula 2] (In the formula, L, T, and * are the same as above.)

3. The carbon nanotube dispersion liquid according to Claim 2, wherein the partial structure represented by the formula (P1) is represented by any one of the following formulas (P2-1) to (P2-3). [Chemical Formula 3] (In the formula, * is the same as above.)

4. The carbon nanotube dispersion liquid according to Claim 1, wherein the polymer contains a repeating unit represented by the following formula (C1-1) or (C1-2). [Chemical Formula 4] (In the formula, R c1 and R c2 each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, R m represents a hydrogen atom or a methyl group, and n represents a natural number. L, R, T, and * are the same as described above.)

5. The carbon nanotube dispersion liquid according to any one of Claims 1 to 4, wherein the solvent contains one or more selected from the group consisting of water and a hydrophilic solvent.

6. The carbon nanotube dispersion liquid according to any one of Claims 1 to 5, wherein the polymer having an oxazoline group in a side chain is a polymer obtained by radical polymerization of an oxazoline monomer represented by the following formula (1). 【Chemical Formula 5】 (In the formula, X represents a polymerizable carbon-carbon double bond-containing group, and R 1 to R 4 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms.)

7. The carbon nanotube dispersion liquid according to any one of Claims 1 to 6, wherein the addition amount of the polymer having a partial structure represented by the formula (P1) in a side chain is 10 to 1,000 parts by mass with respect to 100 parts by mass of the carbon nanotube.

8. The carbon nanotube dispersion liquid according to any one of Claims 1 to 7, wherein the addition amount of the dispersant is 5 to 700 parts by mass with respect to 100 parts by mass of the carbon nanotube.

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