JP2012251129A - Conductive ink and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide conductive ink that is easily mixed with an organic solvent, is stably dissolved or dispersed, and has high processability, high conductivity and high transparency.SOLUTION: In the conductive ink, a polymer represented by chemical formula (I) and a dopant are dispersed or dissolved in the solvent at a particle size of 25 μm or less. In the formula, Ris a hydrogen atom, or a linear, branched or cyclic 1-20C alkyl group that may have a substituent; Rand Rare mutually independent and each of them is a hydrogen atom, or a linear, branched or cyclic 1-20C alkyl group or alkoxy group that may have a substituent; and m is 0 or 1.

Description

  The present invention relates to a conductive ink capable of forming a conductive film having good solubility or dispersibility of the polymer component contained therein and excellent in transparency and conductivity when the conductive film is formed, and a method for producing the same About.

  A polymer obtained by polymerizing a compound having a 5-membered ring structure or a 6-membered ring structure in which a hetero atom exists inside or outside of the ring, such as pyrrole, thiophene, aniline, or the like, or a compound having a hydrocarbon aromatic ring structure, It has conductivity. Use of these polymers as semiconductor materials (semiconductors) for various organic electronic members such as solid electrolytic transistors, organic thin film transistors, and individual identification (RFID) devices using radio waves has been studied. In addition, these doped polymers have electrical conductivity, and the conductive composition includes transparent electrodes such as liquid crystal displays, plasma displays, organic EL displays, electrochromic displays, solar cells, and touch panels. It has been studied for use in polymer solid electrolytic capacitors, secondary battery electrodes, thermoelectric conversion materials, electromagnetic shielding materials, and the like. Also, by processing into conductive ink, a fine conductive pattern can be formed on an insulating substrate, so that electrical and electronic fields such as formation of conductive circuits on printed boards, formation of display electrodes, electromagnetic field shielding of PDPs, etc. Available in

  The most widely applied transparent conductive film is a vapor-deposited film of indium-tin composite oxide (ITO), but there is a problem that it is necessary to form a film at a high temperature and the film formation cost is high. The ITO film formed by the coating film formation method also needs to be formed at a high temperature, and its conductivity depends on the degree of dispersion of ITO and has a high haze value. In addition, an inorganic oxide film such as ITO is likely to crack due to the bending of the base material, and therefore the conductivity tends to decrease.

  As a transparent conductive film using an organic material, one using a conductive polymer that can be formed at low temperature and low cost has been proposed. For example, as an example of polythiophene, a composite (PEDOT / PSS) of poly (3,4-ethylenedioxythiophene) and polystyrene can be given. It is one of conductive polymers with high conductivity, and is partly put into practical use as a transparent electrode for touch panel applications, and is also being studied as a transparent electrode for organic thin film solar cells and organic EL. (Non-Patent Document 1). However, PEDOT / PSS is mainly water-dispersed, and there has been a concern in the electronics field that it may cause device performance degradation due to water contamination. Further, it is known that the dispersed particles aggregate, and improvement has been desired.

In recent years, development of conductive polymers that exhibit solubility or dispersibility in organic solvents has been actively conducted. Patent Document 1 and Non-Patent Document 2 report that a copolymer containing dithienopyrrole having a long-chain alkyl group as a structural unit has good conductivity. However, the dithienopyrrole copolymer shows good solubility in an organic solvent in a dedoping state, but does not show solubility / dispersibility in an organic solvent in a state doped with a dopant such as iodine, and has good processability. The above-mentioned application development could not be expected.
Under such circumstances, it has been desired to develop a conductive ink that exhibits solubility or dispersibility in an organic solvent.

US2008-0262183

Solar Energy Materials & Solar Cells, 2006, 90, 3520-3530 Journal of American Chemical Society, 2008, 130, 13167-13176.

  The present invention has been made to solve the above-mentioned problems, and can be easily mixed with an organic solvent, stably dissolved and dispersed, has excellent workability, and has high conductivity and transparency. An object of the present invention is to provide a conductive ink that is useful as a transparent electrode material and the like that can be used in ink jet printing or the like.

（式（Ｉ）中、Ｒ^１は、水素原子、又は置換基を有していてもよい炭素数１から２０の直鎖状、分岐状、若しくは環状のアルキル基であり、Ｒ^２およびＲ^３はそれぞれ独立して、水素原子、又は置換基を有していてもよい炭素数１から２０の直鎖状、分岐状、若しくは環状のアルキル基又はアルコキシ基であり、ｍは０又は１である。） The conductive ink according to claim 1, which has been made to achieve the above object, has a polymer composed of a unit represented by the following chemical formula (I) and a dopant in a solvent. Dispersed or dissolved with a particle size of 25 μm or less.

(In formula (I), R ¹ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms which may have a substituent, and R ² and R ^3. Each independently represents a hydrogen atom, or a linear, branched, or cyclic alkyl group or alkoxy group having 1 to 20 carbon atoms that may have a substituent, and m is 0 or 1. .)

（式中、Ｒ^１からＲ^３は前記定義の通りである。） The method for producing a conductive ink according to claim 5 is a method in which a compound represented by the following chemical formula (II) is polymerized in a solvent.

(Wherein R ¹ to R ³ are as defined above.)

  According to a seventh aspect of the present invention, there is provided a method for producing a conductive ink, which comprises doping a polymer represented by the chemical formula (I) in a solvent.

［式（III）中、Ｒ^１は、水素原子、又は置換基を有していてもよい炭素数１から２０の直鎖状、分岐状、若しくは環状のアルキル基であり、Ｒ⁴およびＲ⁵はそれぞれ独立して、水素原子、又は下記化学式（IV）、若しくは下記化学式（Ｖ）であり、
−Ｗ−〔（ＣＨ_２）_ａ−Ｘ〕_ｂ−Ｒ^６ ・・・ （IV）
−Ｍ−Ｙ−〔（ＣＨ_２）_ｃ−Ｚ〕_ｄ−Ｒ^７ ・・・（Ｖ）
式（IV）中、Ｒ⁶は水素原子、置換基を有していてもよい炭素数１から２０の直鎖状、若しくは分岐状のアルキル基であり、ＷおよびＸはそれぞれ独立して酸素原子、又は硫黄原子であり、ａは１〜５、ｂは１〜３０であり、
式（Ｖ）中、Ｒ^７は水素原子、置換基を有していてもよい炭素数１から２０の直鎖状、若しくは分岐状のアルキル基であり、Ｍは炭素数１から１０のアルキレン基であり、ＹおよびＺはそれぞれ独立して酸素原子、又は硫黄原子であり、ｃは１〜５、ｄは１〜３０である。］ The dithienopyrrole compound according to claim 9 is represented by chemical formula (III).

[In Formula (III), R ¹ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms which may have a substituent, and R ⁴ and R ⁵ Are each independently a hydrogen atom, the following chemical formula (IV), or the following chemical formula (V),
-W - _{[(CH 2)} a -X] _b -R ⁶ ··· (IV)
-M-Y - _{[(CH 2)} c -Z] _d -R ⁷ ··· (V)
In the formula (IV), R ⁶ is a hydrogen atom, an optionally substituted linear or branched alkyl group having 1 to 20 carbon atoms, and W and X are each independently an oxygen atom. Or a sulfur atom, a is 1 to 5, b is 1 to 30,
In the formula (V), R ⁷ is a hydrogen atom, an optionally substituted linear or branched alkyl group having 1 to 20 carbon atoms, and M is an alkylene group having 1 to 10 carbon atoms. Y and Z are each independently an oxygen atom or a sulfur atom, c is 1 to 5, and d is 1 to 30. ]

  Since the conductive ink of the present invention is stably dissolved and / or dispersed in an organic solvent, it is excellent in processability and film formability. Furthermore, this conductive ink is excellent in transparency and conductivity, and can be used for organic electronic materials such as a transparent conductive film. In addition, the conductive ink of the present invention can be manufactured in large quantities in a general organic solvent at a reduced manufacturing cost.

  Hereinafter, although the form for implementing this invention is demonstrated in detail, the scope of the present invention is not limited to these forms.

  The conductive ink of the present invention is composed of a polymer having a repeating unit represented by the chemical formula (I), that is, an alternating copolymer of dithienopyrrole and thiophene or bithiophene, a dopant, and a solvent.

In the chemical formulas (I) to (III), the linear, branched or cyclic alkyl group having 1 to 20 carbon atoms which may have a substituent represented by R ¹ , R ² and R ³ For example, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-decyl group, n-dodecyl group, n-hexadecyl group, isopropyl Group, isobutyl group, sec-butyl group, 2-methylhexyl group, 2-ethylhexyl group, cyclohexyl group, cyclopropyl group and the like.

In the chemical formulas (I) and (II), examples of the linear, branched, or cyclic alkoxy group having 1 to 20 carbon atoms that may have a substituent represented by R ² and R ³ include, for example, Methoxy group, ethoxy group, propoxy group, n-hexyloxy group, n-octyloxy group, n-decyloxy group, n-dodecyloxy group, n-hexadecyloxy group, 2-methylhexyloxy group, 2-ethylhexyloxy Group and the like.

In the chemical formula (III), R ⁴ and R ⁵ are each independently a hydrogen atom, the following chemical formula (IV), or the following chemical formula (V).
-W - _{[(CH 2)} a -X] _b -R ⁶ ··· (IV)
-M-Y - _{[(CH 2)} c -Z] _d -R ⁷ ··· (V)

In the formula (IV), R ⁶ is a hydrogen atom or a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, and W and X are each independently oxygen It is an atom or a sulfur atom, a is 1-5, b is 1-30. In the formula (V), R ⁷ is a hydrogen atom or an optionally substituted linear or branched alkyl group having 1 to 20 carbon atoms, and M is an alkylene having 1 to 10 carbon atoms. And Y and Z are each independently an oxygen atom or a sulfur atom, c is 1 to 5, and d is 1 to 30.

Examples of the substituent that R ^{1 to} R ³ may have in the chemical formulas (I) to (III) include an alkoxy group, a halogen atom, a hydroxyl group, and an alkylthio group. Alkoxy or alkylthio group is preferred as the substituent R ² and R ³ have. The alkoxy group is further substituted with an alkoxy group, and as represented by the following chemical formula (IV ′) or (V ′), at least one of R ² and R ³ is a polyalkylene glycol chain such as a polyethylene glycol chain. It may be formed.
—O — [(CH ₂ ) _a —O] _b —R ⁶ (IV ′)
-M-O - _{[(CH 2)} c -O] _d -R ⁷ ··· (V ')

In formula (IV ′) and formula (V ′), R ⁶ , R ⁷ , M, a, b, c and d are as defined above, and O is an oxygen atom.

Examples of the alkyl group which may have a substituent represented by R ⁶ and R ⁷ include the same as those described for R ¹ , and the substituent which R ¹ may also have as the substituent. Examples thereof are the same as those exemplified as the group.

Examples of R ⁴ and R ⁵ represented by the formula (IV) or (V) include 2-methoxyethoxy group, 2- (2-methoxyethoxy) ethoxy group, and 2- (2-ethoxy (2-methoxy). Ethoxy)) ethoxy group, 3-methoxypropoxy group, 3- (3-methoxypropoxy) propoxy group, 3- (3-propoxy (3-methoxypropoxy)) propoxy group, (2- (2-methoxyethoxy) ethoxy) Methyl group, (3- (3-methoxypropoxy) propoxy) methyl group, 2-methylthioethylthio group, 2- (2-methylthioethylthio) ethylthio group, 2- (2-ethylthio (2-methylthioethylthio)) Ethylthio group, 3-methylthiopropylthio group, 3- (3-methylthiopropylthio) propylthio group, 3- (3-propylthio (3-me Tilthiopropylthio)) propylthio group, (2- (2-methylthioethylthio) ethylthio) methyl group, (3- (3-methylthiopropylthio) propylthio) methyl group, and the like.

Examples of R ² and R ³ represented by the formula (IV ′) or (V ′) include 2-methoxyethoxy group, 2- (2-methoxyethoxy) ethoxy group, and 2- (2-ethoxy (2). -Methoxyethoxy)) ethoxy group, 3-methoxypropoxy group, 3- (3-methoxypropoxy) propoxy group, 3- (3-propoxy (3-methoxypropoxy)) propoxy group, (2- (2-methoxyethoxy) Ethoxy) methyl group, (3- (3-methoxypropoxy) propoxy) methyl group, and the like.

  The polymer represented by the chemical formula (I) is preferably a repeating polymer of a single structural unit. The bonding arrangement in the structure may be a head-tail repeating structure arranged in a positional manner, or a head-head repeating structure and / or a tail-tail repeating structure. The number average molecular weight of these polymers is preferably in the range of 1000 to 2,000,000, and more preferably in the range of 2000 to 500,000. The monomer unit in the present invention has a structure in which dithienopyrrole and thiophene are linked, or a structure in which thiophene-dithienopyrrole-thiophene is linked (that is, Is a unit).

  The conductive ink of the present invention is preferably obtained by dissolving or dispersing, in a solvent containing at least an organic solvent, a polymer obtained by imparting conductivity (doping) to the polymer represented by the chemical formula (I). Can do. The median particle size of the polymer dispersed or dissolved in the conductive ink measured by a scattering type particle size distribution measuring device is required to be 25 μm or less in order to apply the ink uniformly to the substrate. It is preferably from 01 to 25 μm, and more preferably from 0.01 to 2 μm.

  The dopant is not particularly limited as long as the conductivity can be improved by oxidizing the polymer represented by the chemical formula (I), and various known anions can be used. A dopant that is an anion functions as a counter anion for a polymer that is oxidized and has a positive charge.

Examples of the dopant include an anion of a group 5B element such as PF ₆ ⁻ , SbF ₆ ⁻ , AsF ₆ ^— ; an anion of a group 3B element such as BF ₄ ^— ; a halogenate anion such as ClO ₄ ^— ; AlCl ₄ ⁻ , FeCl ₄ ^-, SnCl ₅ ^- metallic anion, such as, nitric acid anion (NO ₃ ^-); sulfate anions ^_(SO 4 2-); p- toluenesulfonate anion, a naphthalenesulfonic acid ^{_{anion, CH 3 SO 3 -, CF}} 3 SO ₃ ^- organic sulfonic acid anion such _as, and the like; modified polymers with and above anionic species in the main chain or side ^{_{chain; CF 3 COO - -, C}} 6 H 5 COO and the like carboxylic acid anions. However, when a halogen anion such as I ⁻ or Br ⁻ is used as a dopant, the dispersibility of the resulting conductive ink tends to decrease.

  The dopant contained in this invention may be used individually by 1 type, and may be used in combination of 2 or more type. The method for adding the dopant is not particularly limited. For example, after polymerizing the monomer, a desired dopant may be appropriately added to the obtained polymer. When the monomer is chemically oxidatively polymerized or when the polymer is subjected to chemical oxidative doping, an anion derived from an oxidant used for polymerization or doping can be used as a dopant. Moreover, when carrying out the electrolytic polymerization of a monomer, or when performing electrolytic doping to a polymer, the anion derived from the electrolyte used for superposition | polymerization or doping can be used as a dopant.

  There is no restriction | limiting in particular in the content rate of the dopant in the electroconductive ink of this invention, Although it can select arbitrarily, It is the range of 1-50 mass parts with respect to 100 mass parts of polymers shown by Chemical formula (I). And preferred. The content can be appropriately adjusted in the production process.

  In the present invention, water, an organic solvent, and a mixed solvent of water and an organic solvent having an arbitrary ratio can be selected as a solvent as a polymer dispersion medium. Among these, an organic solvent is preferable. The amount of the solvent is preferably 0.05 to 50 w / v%, more preferably 0.1 to 20 w / v%, still more preferably 0.5 to 10 w / v% in terms of the mass of the polymer with respect to the conductive ink. .

  The organic solvent that can be used in the present invention is specifically dichloromethane, 1,2-dichloroethane, chloroform, carbon tetrachloride, chlorobenzene, and dichlorobenzene as halogenated hydrocarbons; triethylamine and pyridine as amines; alcohol As methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, amyl alcohol, ethylene glycol, triethylene glycol, 1,4-butanediol, and glycerol, as ketones, acetone, And methyl ethyl ketone; carbonyl group-containing solvents such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, isophorone, cyclohexanone, and γ-butyl Lactones; as ethers, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, methyl phenyl ether, tetrahydrofuran, cyclopentyl methyl ether, diglyme, and triglyme, and 1,4-dioxane; as aromatic hydrocarbons, Benzene, toluene, xylene, mesitylene, ethylbenzene, and anisole; pentane, hexane, cyclohexane, heptane, octane, and isooctane as aliphatic hydrocarbons; acetonitrile, propiononitrile, and benzonitrile as nitriles; nitromethane as nitro compounds , Nitroethane, nitrobenzene; as amides, N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone; dimethyl sulfoxide as a sulfur-containing solvent; N-methyl-N-butylimidazolinium tetrafluoroborate as an ionic liquid, among others, chloroform, toluene, chlorobenzene, methyl ethyl ketone, isopropanol Is preferred. These may be used alone or in combination of two or more. The organic solvent is not limited to these.

  The surfactant that can be used in the present invention may be any of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant. An agent or a nonionic surfactant is preferred. These may be used alone or in combination of two or more.

  The surfactant used in the present invention improves the dispersibility of the conductive composition in an organic solvent, and the timing of addition can be arbitrarily selected as necessary.

  Next, specific examples of these surfactants are shown, but the present invention is not limited thereto.

  Examples of the anionic surfactant include alkyl sulfonic acid, alkyl benzene sulfonic acid, alkyl carboxylic acid, alkyl naphthalene sulfonic acid, α-olefin sulfonic acid, dialkyl sulfosuccinic acid, α-sulfonated fatty acid, N-methyl-N-oleyl taurine, Petroleum sulfonic acid, alkyl sulfuric acid, sulfated oil and fat, polyoxyethylene alkyl ether sulfuric acid, polyoxyethylene styrenated phenyl ether sulfuric acid, alkyl phosphoric acid, polyoxyethylene alkyl ether phosphoric acid, polyoxyethylene alkyl phenyl ether phosphoric acid, naphthalene sulfone Acid formalin condensate, methyl naphthalene sulfonic acid formalin condensate, butyl naphthalene / naphthalene sulfonic acid formalin condensate, naphthol methylene sulfonic acid formalin condensate, Creo Over preparative oil sulfonic acid formalin condensate, naphthalene sulfonate formaldehyde condensates, polystyrenesulfonic acid, and the like can be mentioned salts thereof.

  Examples of the cationic surfactant include primary to tertiary fatty amines, quaternary ammonium, tetraalkylammonium, trialkylbenzylammoniumalkylpyridinium, 2-alkyl-1-alkyl-1-hydroxyethylimidazolinium, N, Examples include N-alkylmorpholinium, polyethylene polyamine fatty acid amide, urea condensate of polyethylene polyamine fatty acid amide, quaternary ammonium of urea condensate of polyethylene polyamine fatty acid amide, and salts thereof.

  Examples of amphoteric surfactants include N, N-dimethyl-N-alkyl-N-carboxymethyl ammonium betaine, N, N, N-trialkyl-N-sulfoalkylene ammonium betaine, N, N-dialkyl-N, N-bispolyoxyethylene ammonium sulfate betaine, betaines such as 2-alkyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine, aminocarboxylic acids such as N, N-dialkylaminoalkylenecarboxylate, etc. Can be mentioned.

  Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polystyryl phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene alkyl ether, many Polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, polyoxyethylenated castor oil, fatty acid diethanolamide, polyoxyethylene alkylamine, triethanolamine fatty acid partial ester And trialkylamine oxide.

  Further, a fluorosurfactant such as fluoroalkyl carboxylic acid, perfluoroalkyl carboxylic acid, perfluoroalkyl benzene sulfonic acid, perfluoroalkyl polyoxyethylene ethanol may be used.

Here, the alkyl group of the surfactant preferably has 1 to 24 carbon atoms, and more preferably 3 to 18 carbon atoms. The counter cation of the anionic surfactant may be any alkali metal, alkaline earth metal, amine, etc., but Na ⁺ is preferable from the viewpoint of availability. As the counter anion of the cationic surfactant, any halogen is preferable, and Cl ⁻ is more preferable.

  The content of the surfactant is not uniform because it depends on the molecular weight and ability of the surfactant used, but is generally preferably 0.1 to 500% by mass relative to the polymer. -100 mass% is more preferable, and 1-50 mass% is still more preferable.

  The conductive ink of the present invention may contain optional additives as necessary in addition to the constituents of the polymer represented by the chemical formula (I), the dopant, and the solvent including the organic solvent. Well, the order of addition can be arbitrarily selected. The additive can be appropriately selected from known additives, for example, ultraviolet absorbers, antioxidants, deterioration inhibitors, dispersants, surfactants, polymerization inhibitors, surface modifiers, Examples include defoaming agents, plasticizers, and antibacterial agents. These may be used alone or in combination of two or more.

  Subsequently, the compound represented by the chemical formula (VI) is polymerized to form a conductive ink comprising the polymer represented by the chemical formula (I) and the dopant by chemical oxidative polymerization or electrolytic polymerization in a solvent, preferably in an organic solvent. The manufacturing method of the process 1 shown by the following chemical reaction formula (A) to manufacture is demonstrated.

（化学反応式（Ａ）中、Ｒ¹、Ｒ^２、Ｒ^３、ｍは前記定義の通りである。）

(In the chemical reaction formula (A), R ¹ , R ² , R ³ and m are as defined above.)

  Step 1 is a step of producing a conductive ink containing a polymer represented by the chemical formula (I) and a dopant from the monomer compound represented by the chemical formula (VI) by a polymerization reaction. The polymer represented by the chemical formula (I) in the reaction formula (A) represents a doped state, and thus has conductivity. In the production method according to Step 1, in order to improve the regularity of the obtained polymer, when a compound represented by the following chemical formula (II) in which m is 1 is used as the monomer compound, that is, m is 1 in the chemical formula (I). It is preferably used in the case of producing a polymer consisting of the unit.

（式中、Ｒ¹、Ｒ^２、Ｒ^３は前記定義の通りである。）

(Wherein R ¹ , R ² and R ³ are as defined above.)

  In the step 1, it is preferable to add at least one surfactant. The surfactant may be any of anionic, cationic, amphoteric and nonionic, and an anionic surfactant is preferred.

  The polymerization reaction in Step 1 may be either chemical oxidation polymerization or electrolytic polymerization, and is preferably chemical oxidation polymerization. In the case of chemical oxidative polymerization, a polymer represented by chemical formula (I) can be obtained by polymerizing a compound represented by chemical formula (VI) using an oxidizing agent.

  The oxidizing agent used in step 1 may be either an organic or inorganic oxidizing agent, such as ferric chloride, ferric sulfate, ferric perchlorate, ferric nitrate, iron alum, sulfone. Ferric salts such as ferric salts of acids and carboxylic acids are preferred.

  As the sulfonic acid in the ferric salt of sulfonic acid, benzenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, p-toluenesulfonic acid, o-ethylbenzenesulfonic acid, m-ethylbenzenesulfonic acid, p-ethylbenzene Examples include sulfonic acid, p-dodecylbenzenesulfonic acid, dodecylsulfonic acid, naphthalenesulfonic acid, and the like. The carboxylic acid in the ferric salt of carboxylic acid may be any of saturated carboxylic acid and unsaturated carboxylic acid, and may be any of aliphatic carboxylic acid, aromatic carboxylic acid, alicyclic carboxylic acid and the like. .

  The oxidizing agent may be used alone or in combination of two or more. When mixed and used, the oxidant having a dopant action and the oxidant having no dopant action are mixed and used to have one or more ferric salts having a dopant action and a dopant action. One or more ferric salts may be mixed and used.

  The amount of the oxidizing agent used can be about 0.5 to 10 moles per mole of the monomer compound. In the present invention, the preferred amount of ferric salt used per mole of the monomer compound is 2 to 5 moles. Degree.

  In Step 1, the order of addition of the surfactant and the oxidizing agent is not particularly limited and may be any order. After dissolving the compound represented by the chemical formula (II) in the solvent, A method of adding a surfactant and an oxidizing agent in this order is preferable.

  As another production method, as a step 2a represented by the following chemical reaction formula (B), a compound represented by the chemical formula (VII) and a compound represented by the chemical formula (VIII) are subjected to a cross-coupling reaction, whereby the chemical formula (I Step 2b is a step of producing a conductive ink by chemical oxidation doping or electrolytic doping in a solvent, preferably in the presence of an organic solvent and a surfactant. 2 production methods.

（化学反応式（Ｂ）中、Ｒ^１、Ｒ^２、Ｒ^３は前述定義の通りである。ａ及びａ'は、−Ｌi、−Ｎａ、−ＭｇＣｌ、−ＭｇＢｒ、−ＭｇＩ、−ＺｎＣｌ、−ＺｎＢｒ、−ＺｎＩ、−Ｓｎ（Ａｋｙ）_３、−Ｓｉ（ＯＨ）_３、−Ａｌ（Ａｋｙ）_３、−Ｉｎ（Ａｋｙ）_３、−Ｂ（Ａｋｙ）_２、Ｂ（ＯＨ）_２、Ｂ（ＯＡｋｙ）_２などの金属を含む置換基から選ばれる。なお、ここでＡｋｙとは、アルキル基を表す。ｂ及びｂ'はハロゲン原子又はＯＳＯ_２ＣＦ_３基から選ばれる。ｍ’は１又は２である。）

(In the chemical reaction formula (B), R ¹ , R ² and R ³ are as defined above. A and a ′ are -Li, -Na, -MgCl, -MgBr, -MgI, -ZnCl,- ZnBr, —ZnI, —Sn (Aky) ₃ , —Si (OH) _3, —Al (Aky) ₃ , —In (Aky) ₃ , —B (Aky) ₂ , B (OH) ₂ , B (OAky) _{It is} selected from a substituent containing a metal such as _2. Here, Aky represents an alkyl group, b and b ′ are selected from a halogen atom or an OSO ₂ CF ₃ group, and m ′ is 1 or 2. .)

  As a preferred embodiment of the step 2a, for example, a compound represented by the chemical formula (VII) and a compound represented by the chemical formula (VIII) in the presence of a solvent and a transition metal complex in an inert gas atmosphere such as nitrogen and argon. And a cross-coupling reaction. Examples of the metal complex used include metal complexes such as nickel and palladium, and in particular, metal complexes coordinated with phosphines such as tetrakistriphenylphosphine palladium and diphenylphosphinopropane nickel chloride should be used. Is preferred.

  Since step 2a is a cross-coupling reaction, a and a ′ can be combined with b and b ′. That is, when a and a ′ are halogen atoms, b and b ′ are substituents containing a metal. When m ′ is 1, it indicates that compound (VIII) is a thiophene compound, and when m ′ is 2, it indicates that compound (VIII) is a bithiophene compound.

Examples of the cross coupling reaction in step 2a include Stille coupling reaction, Kumada coupling reaction, Hiyama coupling reaction, Negishi coupling reaction, Suzuki coupling reaction and the like. Among these, from the viewpoint of reaction efficiency, a Stille coupling reaction, a Suzuki coupling reaction, or a Kumada coupling reaction is preferably employed, and a Stille coupling reaction and a Suzuki coupling reaction are more suitably employed. In these coupling reactions, b and b ′ in the compound represented by the chemical formula (VIII) represent I or Br. The Stille coupling reaction is a reaction using an organotin compound in which a and a ′ in the compound represented by the chemical formula (VII) are represented by —SnR ₃ or the like. In the Suzuki coupling reaction, B (OH) ₂ , This is a reaction using an organoboron compound represented by B (OAky) ₂ or the like, and the Kumada coupling reaction is a reaction using an organomagnesium compound represented by -MgBr or the like. In addition, a well-known method (For example, Experimental Chemistry Course Vol.18 3.2.2 carbon-carbon coupling p333-352) can be applied to said cross coupling reaction.

As R ¹ in the compound represented by the above chemical formula (VII), the same compounds as those exemplified for the compound represented by the above chemical formula (I) can be used. In addition, the compound described in Chemical Formula (VII) can be synthesized, for example, by the method described in Non-Patent Document 2.

As the thiophene compound (VIII) substituted at the 3-position or 4-position with a substituent, a commercially available product may be used as a starting compound, such as a thiophene compound substituted at the 3-position and 4-position with a substituent. You may use what synthesize | combined by brominating 2-position and 5-position of a raw material with a bromine or N-bromosuccinimide. As R ² and R ³ in the compound represented by the chemical formula (VIII), the same compounds as those exemplified for the compound represented by the above chemical formula (I) can be used.

  The doping in this step 2b may be either chemical oxidation doping or electrolytic doping, and is preferably chemical oxidation doping. In the case of chemical oxidation doping, the polymer represented by the chemical formula (I) can be doped using an oxidizing agent.

  In the step 2b, it is preferable to add at least one surfactant. The surfactant may be any of anionic, cationic, amphoteric and nonionic, and an anionic surfactant is preferred.

  As the oxidizing agent and surfactant used in step 2b, the same ones exemplified in step 1 can be used.

  In step 2b, the order of addition of the surfactant and the oxidizing agent is not particularly limited, and any order may be used. After dissolving the polymer in the solvent, the surfactant and the oxidizing agent are added. The method of adding in the order is preferable.

  In step 2, bithiophene compounds in which bimolecular thiophene compounds having the same or different substituents are bonded can be sequentially introduced. From the viewpoint of simplicity of synthesis, it is preferable to introduce a bithiophene compound having the same substituent.

  The polymer comprising the unit represented by the chemical formula (I) obtained by the production method of Step 1 or Step 2 may have a hydrogen atom, a halogen atom, a coupling residue, etc. as a terminal group. Further, a terminal structure in which these terminal groups are substituted with an end capping agent made of an aromatic halide such as benzene bromide or an aromatic boronic acid compound may be used. Moreover, as long as it is a small quantity which does not impair the effect of the polymer of this invention, you may copolymerize units other than shown by the said Chemical formula (I).

  According to the present invention, a conductive ink having high solubility or dispersibility in an organic solvent can be provided. The conductive ink thus obtained is suitable as a conductive material because it has excellent processability and extremely good conductivity.

  Hereinafter, the present invention will be described more specifically with reference to examples.

温度計、還流冷却器及びマグネチックスターラを備えた内容積２００ｍｌの３口フラスコに窒素雰囲気下、２，６−ビス（トリメチルスタニル）−Ｎ−ドデシル−ジチエノ[３，２−ｂ：２’，３’−ｄ]ピロール（３．０３ｇ、４．５０ｍｍｏｌ）、２−ブロモ−３−ドデシルチオフェン（３．０２ｇ、９．１４ｍｍｏｌ）、トリスジベンジリデンアセトンジパラジウム（１２３ｍｇ、０．１３５ｍｍｏｌ）、トリ（ｏ−トルイル）ホスフィン（１６４ｍｇ、０．５４ｍｍoｌ）およびクロロベンゼン６０ｍｌを加え、系内をアルゴン置換した後、１５０℃にて１時間加熱攪拌した。反応終了後、１００ｍｌの水に反応液を加え、分液漏斗を用いて有機相を分離した。水相を酢酸エチルにより抽出し、先の有機相と混合したものを水により洗浄した後、有機相を無水硫酸マグネシウムにより乾燥した。有機相を減圧下濃縮して得られた残渣をシリカゲルカラムクロマトグラフィー（展開溶媒：ヘキサン／酢酸エチル＝９８／２）を用いて精製し、２，６−ビス（３−ドデシルチオフェン−２−イル）−Ｎ−ドデシル−ジチエノ[３，２−ｂ：２’，３’−ｄ]ピロール（１）を橙色固体として得た（３．１４ｇ、３．７０ｍｍｏｌ、収率８２％）。 Synthesis Example 1 [Synthesis of 2,6-bis (3-dodecylthiophen-2-yl) -N-dodecyl-dithieno [3,2-b: 2 ′, 3′-d] pyrrole (1)]

2,6-bis (trimethylstannyl) -N-dodecyl-dithieno [3,2-b: 2 ′ in a 200 ml internal volume three-necked flask equipped with a thermometer, a reflux condenser and a magnetic stirrer under a nitrogen atmosphere , 3′-d] pyrrole (3.03 g, 4.50 mmol), 2-bromo-3-dodecylthiophene (3.02 g, 9.14 mmol), trisdibenzylideneacetone dipalladium (123 mg, 0.135 mmol), tri (O-Toluyl) phosphine (164 mg, 0.54 mmol) and 60 ml of chlorobenzene were added, the inside of the system was purged with argon, and then heated and stirred at 150 ° C. for 1 hour. After completion of the reaction, the reaction solution was added to 100 ml of water, and the organic phase was separated using a separatory funnel. The aqueous phase was extracted with ethyl acetate, and the mixture with the previous organic phase was washed with water, and then the organic phase was dried over anhydrous magnesium sulfate. The residue obtained by concentrating the organic phase under reduced pressure was purified using silica gel column chromatography (developing solvent: hexane / ethyl acetate = 98/2) to give 2,6-bis (3-dodecylthiophen-2-yl). ) -N-dodecyl-dithieno [3,2-b: 2 ′, 3′-d] pyrrole (1) was obtained as an orange solid (3.14 g, 3.70 mmol, 82% yield).

Its ¹ H-NMR spectral data are as follows and support the structure represented by the chemical formula (1).
¹ H-NMR (270 MHz, CDCl ₃ , TMS) σ: 7.17 (d, 2H, J = 5.4 Hz), 7.00 (s, 2H), 6.94 (d, 2H, J = 5. 4 Hz), 4.19 (t, 2H, J = 6.8 Hz), 2.82 (t, 4H, J = 8.1 Hz), 1.89 (m, 2H), 1.67 (m, 4H) 1.2 (bm, 54H), 0.87 (m, 9H)

合成例１において、２−ブロモ−３−ドデシルチオフェンを、２−ブロモ−３−ドデシルオキシメチルチオフェン（３．１７ｇ、９．１４ｍｍｏｌ）に変更した以外は同様に反応および精製を行い、２，６−ビス（３−ドデシルオキシメチルチオフェン−２−イル）−Ｎ−ドデシル−ジチエノ[３，２−ｂ：２’，３’−ｄ]ピロール（２）を橙色固体として得た（３．２７ｇ、３．６０ｍｍｏｌ、収率８０％）。 Synthesis Example 2 Synthesis of [2,6-bis (3-dodecyloxymethylthiophen-2-yl) -N-dodecyl-dithieno [3,2-b: 2 ′, 3′-d] pyrrole (2) ]

Reaction and purification were performed in the same manner as in Synthesis Example 1 except that 2-bromo-3-dodecylthiophene was changed to 2-bromo-3-dodecyloxymethylthiophene (3.17 g, 9.14 mmol). -Bis (3-dodecyloxymethylthiophen-2-yl) -N-dodecyl-dithieno [3,2-b: 2 ′, 3′-d] pyrrole (2) was obtained as an orange solid (3.27 g, 3.60 mmol, yield 80%).

Its ¹ H-NMR spectrum data is as follows and supports the structure represented by the chemical formula (2).
¹ H-NMR (270 MHz, CDCl ₃ , TMS) σ: 7.20 (d, 2H, J = 5.5 Hz), 7.16 (s, 2H), 7.12 (d, 2H, J = 5. 5 Hz), 4.58 (s, 2H), 4.19 (t, 2H, J = 6.9 Hz), 3.52 (t, 4H, J = 6.7 Hz), 1.88 (m, 2H) 1.66 (m, 4H), 1.2 (bm, 54H), 0.87 (m, 9H)

Synthesis Example 3 [2,6-bis (3- (2- (2-methoxyethoxy) ethoxy) methylthiophen-2-yl) -N-dodecyl-dithieno [3,2-b: 2 ′, 3 ′ -D] Synthesis of pyrrole (3)]

  In the same manner as in Synthesis Example 1, except that 2-bromo-3-dodecylthiophene was changed to 2-bromo-3- (2- (2-methoxyethoxy) ethoxy) methylthiophene (2.69 g, 9.14 mmol). Reaction and purification were carried out to give 2,6-bis (3- (2- (2-methoxyethoxy) ethoxy) methylthiophen-2-yl) -N-dodecyl-dithieno [3,2-b: 2 ′, 3 ′ -D] Pyrrole (3) was obtained as an orange solid (3.27 g, 3.83 mmol, 85% yield).

Its ¹ H-NMR spectrum data is as follows and supports the structure represented by the chemical formula (3).
¹ H-NMR (270 MHz, CDCl ₃ , TMS) σ: 7.19 (d, 2H, J = 4.9 Hz), 7.14 (s, 2H), 7.13 (d, 2H, J = 4. 9 Hz), 4.66 (s, 4H), 4.20 (t, 2H, J = 7.0 Hz), 3.70 (s, 8H), 3.66 (m, 4H), 3.54 (m , 4H), 1.88 (m, 2H), 1.2 (bm, 20H), 0.86 (m, 3H)

Synthesis Example 4 [2,6-bis (3- (2- (2-methoxyethoxy) ethoxy) thiophen-2-yl) -N-dodecyl-dithieno [3,2-b: 2 ′, 3′- d] Synthesis of pyrrole (4)]

  The same reaction as in Synthesis Example 1 except that 2-bromo-3-dodecylthiophene was changed to 2-bromo-3- (2- (2-methoxyethoxy) ethoxy) thiophene (2.57 g, 9.14 mmol). And purification, 2,6-bis (3- (2- (2-methoxyethoxy) ethoxy) thiophen-2-yl) -N-dodecyl-dithieno [3,2-b: 2 ′, 3′-d ] Pyrrole (4) was obtained as an orange solid (1.11 g, 1.49 mmol, 2,6-bis (trimethylstannyl) -N-dodecyl-dithieno [3,2-b: 2 ′, 3′-d ] Yield 33% based on pyrrole).

Its ¹ H-NMR spectrum data is as follows and supports the structure represented by the chemical formula (4).
¹ H-NMR (270 MHz, acetone-D ₆ , TMS) σ: 7.41 (s, 2H), 7.26 (d, 2H, J = 5.7 Hz), 7.07 (d, 2H, J = 5.7 Hz), 4.32 (m, 6H), 3.91 (m, 4H), 3.72 (m, 4H), 3.55 (m, 4H), 3.32 (s, 6H), 1.92 (m, 2H), 1.4-1.2 (bm, 18H), 0.86 (t, 3H, J = 5.4 Hz)

温度計、還流冷却器及びマグネチックスターラを備えた内容積５０ｍｌの三口フラスコに窒素雰囲気下、２，６−ビス（トリメチルスタニル）−Ｎ−ドデシル−ジチエノ[３，２−ｂ：２’，３’−ｄ]ピロール（３１６ｍｇ、０．４７ｍｍｏｌ）、５，５’−ジブロモ−４，４’−ジドデシル−２，２’−ビチオフェン（３１１ｍｇ、０．４７ｍｍｏｌ）、トリスジベンジリデンアセトンジパラジウム（１２．６ｍｇ、１３.８ｕｍｏｌ）、トリ（ｏ−トルイル）ホスフィン（１７．２ｍｇ、５６．５ｕｍｏｌ）およびクロロベンゼン１５ｍｌを加え、系内を窒素置換した後、１４０℃にて４８時間加熱攪拌した。反応終了後、５％塩酸−メタノール溶液に滴下し、再沈殿した。沈殿物をろ別し、メタノール、ヘキサンでソックスレー精製を行った後に、クロロホルムで抽出した。クロロホルムを減圧留去して、Ｎ−ドデシル−ジチエノ[３，２−ｂ：２’，３’−ｄ]ピロールと４，４’−ジドデシル−２,２’−ビチオフェンの共重合体（５）を得た。 Synthesis Example 4 Synthesis of Copolymer (5) of [N-dodecyl-dithieno [3,2-b: 2 ′, 3′-d] pyrrole and 4,4′-didodecyl-2,2′-bithiophene ]

2,6-bis (trimethylstannyl) -N-dodecyl-dithieno [3,2-b: 2 ′, under a nitrogen atmosphere in a three-necked flask with an internal volume of 50 ml equipped with a thermometer, a reflux condenser and a magnetic stirrer 3′-d] pyrrole (316 mg, 0.47 mmol), 5,5′-dibromo-4,4′-didodecyl-2,2′-bithiophene (311 mg, 0.47 mmol), trisdibenzylideneacetone dipalladium (12 1.6 mg, 13.8 umol), tri (o-toluyl) phosphine (17.2 mg, 56.5 umol) and 15 ml of chlorobenzene were added, the inside of the system was purged with nitrogen, and the mixture was heated and stirred at 140 ° C. for 48 hours. After completion of the reaction, the mixture was added dropwise to a 5% hydrochloric acid-methanol solution and reprecipitated. The precipitate was collected by filtration, subjected to Soxhlet purification with methanol and hexane, and then extracted with chloroform. Chloroform was distilled off under reduced pressure to give a copolymer of N-dodecyl-dithieno [3,2-b: 2 ′, 3′-d] pyrrole and 4,4′-didodecyl-2,2′-bithiophene (5) Got.

<Example 1>
Compound (1) (85 mg) and chloroform (5 ml) were added and dissolved in a 50 ml three-necked flask equipped with a thermometer and a condenser. A suspension composed of ferric sulfate n-hydrate (199 mg), aerosol OT (100 mg; anionic surfactant), chloroform (1 ml) and distilled water (0.25 ml) was added dropwise thereto. Then, it stirred at 60 degreeC for 24 hours. The obtained dispersion was transferred to a separatory funnel, washed three times with distilled water (10 ml), dried over sodium sulfate, and a conductive material containing a polymer composed of units represented by the chemical formula (I) and a dopant. An ink was obtained as a dispersion (1.0 wt%). As a result of measuring the molecular weight of the polymer using GPC using standard polystyrene as a calibration curve, the number average molecular weight (Mn) was 5400, the weight average molecular weight (Mw) was 7600, and Mw / Mn was 1.41.

<Example 2>
The same operation was performed except that ferric perchlorate n hydrate (177 mg) was used instead of the iron sulfate n hydrate of Example 1.

<Example 3>
The same operation was performed except that anhydrous ferric chloride (81 mg) was used in place of the iron sulfate n-hydrate of Example 1.

<Example 4>
The same operation was performed except that chlorobenzene was used instead of chloroform in Example 1.

<Example 5>
The same operation was performed except that methyl ethyl ketone was used instead of chloroform in Example 1.

<Example 6>
The same operation was performed except that 2-propanol was used instead of chloroform in Example 1.

<Example 7>
The same operation was performed except that the compound (2) was used instead of the compound (1) of Example 1.

<Example 8>
The same operation was performed except that the compound (3) was used instead of the compound (1) of Example 1.

<Example 9>
The same operation was performed except that the compound (4) was used instead of the compound (1) of Example 1.

<Example 10>
Copolymer (5) (10 mg) was dissolved in chloroform (1 ml), aerosol OT (100 mg; anionic surfactant) and ferric perchlorate (21 mg) were added, and reacted at 60 ° C. for 1 hour. A conductive ink containing a polymer consisting of the unit represented by (I) and a dopant was obtained as a dispersion (1.0 w / v%).

<Comparative Example 1>
Copolymer (5) (14.2 mg) was dissolved in toluene (1 ml), iodine (6.2 mg) was added, and the mixture was reacted at room temperature for 10 minutes to obtain a dispersion.

<Comparative example 2>
The same operation was performed except that chloroform was used instead of toluene in Comparative Example 1.

(Measurement of median particle size)
The median particle size of the dispersions prepared in Examples 1 to 10 and Comparative Examples 1 and 2 was measured using a scattering type particle size distribution measuring apparatus (LA-950V2 manufactured by Horiba). The results are shown in Table 1.

(Measurement of total light transmittance)
The dispersions prepared in Examples 1 to 10 and Comparative Examples 1 and 2 were dropped onto a white glass substrate (2.5 cm × 2.5 cm × 0.1 cm) and about 50 nm using a spin coater (1000 rpm, 30 seconds). A thin film was prepared. All of the thin films obtained in Examples 1 to 10 had a total light transmittance of 80% or more.

(Measurement of surface resistance)
The thin films of Examples 1 to 10 and Comparative Examples 1 and 2 were prepared in the same manner as the measurement of the total light transmittance, and the surface resistance value was measured with a 4-probe type measuring instrument (MCP-T610 manufactured by Mitsubishi Chemical Corporation). It was measured. The results are shown in Table 1.

  As is clear from Table 1, the conductive inks obtained in Examples 1 to 10 produce a uniform thin film because the polymer and the dopant are dispersed or dissolved in a solvent with a particle size of 25 μm or less. The obtained thin film had electrical conductivity. Among them, the inks made of the dispersions prepared in Examples 1, 2, 7, 8 and 9 have a median particle size of 1 μm or less, can produce a more uniform thin film, and have excellent surface resistance values. . On the other hand, in Comparative Examples 1 and 2, the median particle diameter exceeded 25 μm, the dispersibility was poor, a uniform thin film could not be produced, and the surface resistance value could not be measured.

  From the above result, it has confirmed that the conductive ink containing a conductive composition can be manufactured simply by this invention.

  The conductive ink of the present invention is highly transparent and can be used as a material for a transparent conductive film exhibiting excellent conductivity. Moreover, the transparent conductive film formed with this conductive ink is used for transparent electrodes such as liquid crystal displays, plasma displays, electroluminescent displays, electrochromic displays, solar cells, touch panels; electrolytes for electrolytic capacitors, electrodes for secondary batteries, connections Materials, polymer semiconductor elements, sensors, UV absorbers, heat ray absorbers; antistatic agents such as antistatic coatings and antistatic packaging materials; electromagnetic wave shielding agents; and transfer belts, developing rolls, charging rolls, transfer rolls, etc. It can be used for electrophotographic equipment parts.

Claims (10)

A conductive ink in which a polymer composed of units represented by the following chemical formula (I) and a dopant are dispersed or dissolved in a solvent with a particle size of 25 μm or less.

(In formula (I), R ¹ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms which may have a substituent, and R ² and R ^3. Each independently represents a hydrogen atom, or a linear, branched, or cyclic alkyl group or alkoxy group having 1 to 20 carbon atoms that may have a substituent, and m is 0 or 1. .)   The conductive ink according to claim 1, wherein m in chemical formula (I) is 1.   The conductive ink according to claim 1, wherein the solvent contains an organic solvent.   The conductive ink according to claim 1, further comprising at least one surfactant. The method for producing a conductive ink according to claim 1, wherein a compound represented by the following chemical formula (II) is polymerized in a solvent.

(Wherein R ¹ to R ³ are as defined above.)   The method for producing a conductive ink according to claim 4, wherein the compound represented by the chemical formula (II) is polymerized in the presence of an organic solvent and a surfactant.   The method for producing a conductive ink according to claim 1, wherein the polymer represented by the chemical formula (I) is doped in a solvent.   The method for producing a conductive ink according to claim 4, wherein the polymer represented by the chemical formula (I) is doped in the presence of an organic solvent and a surfactant. A dithienopyrrole compound represented by the chemical formula (III).

(In the formula, R ¹ is a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms which may have a substituent, and R ⁴ and R ⁵ are each independently selected. A hydrogen atom or the following chemical formula (IV) or the following chemical formula (V):
-W - _{[(CH 2)} a -X] _b -R ⁶ ··· (IV)
-M-Y - _{[(CH 2)} c -Z] _d -R ⁷ ··· (V)
In the formula (IV), R ⁶ is a hydrogen atom or a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, and W and X are each independently oxygen An atom or a sulfur atom, a is 1 to 5, b is 1 to 30,
In the formula (V), R ⁷ is a hydrogen atom, an optionally substituted linear or branched alkyl group having 1 to 20 carbon atoms, and M is an alkylene group having 1 to 10 carbon atoms. Y and Z are each independently an oxygen atom or a sulfur atom, c is 1 to 5, and d is 1 to 30. ) In the chemical formula (I), at least one of R ² and R ³ is the following chemical formula (IV ′) or the following chemical formula (V ′):
—O — [(CH ₂ ) _a —O] _b —R ⁶ (IV ′)
-M-O - _{[(CH 2)} c -O] _d -R ⁷ ··· (V ')
(In the formula (IV ′), R ⁶ is a hydrogen atom, or a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, O is an oxygen atom, a is 1-5, b is 1-30,
In the formula (V ′), R ⁷ is a hydrogen atom, an optionally substituted linear or branched alkyl group having 1 to 20 carbon atoms, and M is an alkylene having 1 to 10 carbon atoms. And O is an oxygen atom, c is 1 to 5, and d is 1 to 30. )
The conductive ink according to claim 1, which is represented by: