Method for producing conductive polymer solution

Abstract

To provide a production method for conductive polymer solution capable of obtaining the solution low in iron ion content without performing removal treatment by a cation exchange resin.SOLUTION: Disclosed is a production method for a conductive polymer solution including polythiophene which includes at least two repeating units selected from the group consisting of a repeating unit which has one alkyloxymethyl group in which a metal sulfonium or sulfonate group bonds onto a 1,4-dioxane ring and is derived from 3,4-ethylenedioxythiophene, and a repeating unit in which the main chain including the thiophene ring of the above repeating unit has a resonance structure. The method is characterized by including (i) a polymerization step of obtaining a polymer solid or polymer solution by polymerizing a monomer necessary for obtaining polythiophene, and (ii) a dissolution step of obtaining a polymer solution by mixing the polymer solid with a solvent when the polymer obtained in the polymerization step is the polymer solid.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a solution of a self-doping conductive polymer having a polythiophene skeleton. [Background technology]

[0002] In recent years, semiconductor technology has made rapid progress, leading to the creation of a huge electronics-related industry and an advanced information society. Among these, applications of conductive polymers to electronic products, such as liquid crystal displays (LCDs) and organic electroluminescence (OLEDs), have become widespread in various fields, including televisions, computers, and various mobile devices that have become popular in recent years, and have made remarkable progress.

[0003] As materials supporting the electronics industry, externally doped conductive polymers have been developed in which π-conjugated polymers, such as polyacetylene, polythiophene, polyaniline, and polypyrrole, are doped with electron-accepting compounds as dopants. However, these polymers have problems such as difficulty in purification due to their low solubility and difficulty in maintaining stable doping. To address this problem, so-called self-doped conductive polymers have been developed, which have substituents (sulfo groups, sulfonate groups, etc.) in the polymer backbone, either directly or via a spacer, that provide both water solubility and doping properties. Examples of such polymers include sulfonated polyaniline and sulfonated polythiophene (see, for example, Non-Patent Documents 1 and 2). Among these, poly(4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butanesulfonic acid) (PEDT-S), which is substituted with linear alkylenesulfonic acid groups, have been reported (see, for example, Patent Document 1 and Non-Patent Documents 3 and 4). The applicant of the present invention has also reported a self-doped conductive polymer that combines high conductivity with excellent water solubility (see, for example, Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4974095 [Patent Document 2] International Publication No. 2014 / 007299 [Patent Document 3] Patent Publication No. 2020-59837 [Non-patent literature]

[0005] [Non-Patent Document 1] Journal of the American Chemical Society, 117, 10055-10062(1995) [Non-patent document 2] Journal of the Chemical Society, Chemical Communications, 23, 1694-1695(1990) [Non-patent document 3] Chemistry of Materials, 21, 1815-1821(2009) [Non-patent document 4] Advanced Materials, 23, 4403-4408(2011) Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned prior art (Patent Document 3), self-doped conductive polymers are synthesized by oxidative polymerization, but this method tends to leave metal ions, especially iron ions, derived from the catalyst or oxidant as impurities in the polymerization product. Since these iron ion impurities cause degradation of device characteristics and durability in applications such as organic electroluminescence (EL) and LCDs, a treatment for removing iron ions from conductive polymers using a cation exchange resin has been proposed. However, removal using a cation exchange resin increases the number of manufacturing steps, increases variable costs, and increases environmental impact, making reductions desirable. [Means for solving the problem]

[0007] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by bringing at least one pair of electrodes into contact with a thiophene monomer solution containing an acid and applying a potential difference between the electrodes to cause an electrochemical oxidation polymerization reaction. In other words, it is possible to provide a conductive polymer having a low iron ion content without carrying out a removal treatment using a cation exchange resin, and have completed the present invention.

[0008] That is, the present invention relates to a self-doping conductive polymer solution having a polythiophene skeleton, as shown below, obtained by the above-mentioned means, and a method for producing the same.

[0009] [1] A repeating structure represented by the following general formula (2) and a repeating structure represented by the following general formula (3)

[0010] [ka]

[0011] [ka]

[0012] [In the above general formula (2), M + Each of R independently represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium cation. 2 represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a halogen atom. m represents an integer of 1 to 6, and n represents 0 or 1.] A method for producing a conductive polymer solution containing polythiophene containing at least two or more repeating structures selected from the group consisting of repeating structures represented by (i) a polymerization step of bringing at least one pair of electrodes into contact with a solution containing at least a thiophene monomer represented by the following general formula (1), a solvent, and an acid, and applying a potential difference between the electrodes to polymerize the monomer, thereby obtaining a polymer solid or a polymer solution; (ii) a dissolving step in which, when the polymer obtained in the polymerization step is a polymer solid, the polymer solid is mixed with a solvent to obtain a polymer solution; A method for producing a conductive polymer solution, comprising:

[0013] [ka]

[0014] [In the above general formula (1), M + represents a hydrogen ion, an alkali metal ion, an ammonium ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. 2 represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a halogen atom. m represents an integer of 1 to 6, and n represents 0 or 1.] [2] The aforementioned R 2 is a methyl group.

[0015] [3] The production method according to [1] or [2], wherein in the polymerization step, the concentration of the monomer is 0.1 to 30% by weight.

[0016] [4] The production method according to any one of [1] to [3], wherein in the polymerization step, when the charged solution is an aqueous solution, its pH is in the range of 0 to 6.5.

[0017] [5] The method according to any one of [1] to [4], wherein in the polymerization step, the potential applied to the anode is in the range of 0 to +5 V relative to a silver / silver chloride electrode.

[0018] [6] [1] to [5], the manufacturing method according to any one of [1] to [5], (iii) an anion exchange step of contacting the polymer solution obtained in the polymerization step or dissolution step with an anion exchange resin to exchange the anions in the polymer solution for hydroxide ions; The manufacturing method further comprises: [Effects of the Invention]

[0019] According to the present invention, it is possible to produce and provide a self-doped conductive polymer with a lower amount of residual metal ions than conventional polymers. The self-doped conductive polymer of the present invention is extremely useful industrially in that it can improve the performance of organic electroluminescence (EL) displays, LCDs, capacitors, etc. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in detail below.

[0021] The present invention relates to a method for producing a conductive polymer solution as described above.

[0022] In the above general formulas (1) and (2), M + are each independently hydrogen ions, alkali metal ions, ammonium ions (NH4 + ), the conjugate acid of an amine compound, or a quaternary ammonium cation.

[0023] The alkali metal ions are not particularly limited, but preferred examples include Li ions, Na ions, and K ions.

[0024] The conjugate acid of the amine compound is a hydrone (H + ) is added to form a cationic species, and any amine compound that reacts with a sulfonic acid group to form a conjugate acid is acceptable.

[0025] The amine compound in the conjugate acid of the amine compound is not particularly limited, but for example, a compound represented by the general formula N(R 1 ) 3, and amine compounds having sp2 hybrid orbitals such as pyridines and imidazoles.

[0026] The above-mentioned substituent R 1 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkyl group having 1 to 6 carbon atoms and having a substituent.

[0027] The alkyl group having 1 to 6 carbon atoms is not particularly limited, but examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a cyclopentyl group, an n-hexyl group, a 2-ethylbutyl group, and a cyclohexyl group.

[0028] The alkyl group having 1 to 6 carbon atoms and having a substituent is not particularly limited, but examples thereof include an alkyl group having 1 to 6 carbon atoms and having a group selected from the group consisting of a halogen atom, an alkyl group having 1 to 6 carbon atoms, an amino group, and a hydroxy group, and specific examples thereof include, but are not particularly limited to, a trifluoromethyl group, a 2-hydroxyethyl group, etc.

[0029] Among these, from the viewpoint of availability, the substituent R 1 are each independently preferably a hydrogen atom, a methyl group, an ethyl group, or a 2-hydroxyethyl group.

[0030] General formula N(R 1The amine compound represented by formula (3) is not particularly limited, but examples thereof include ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, isopropylamine, n-butylamine, tertiary butylamine, hexylamine, aminoethanol, dimethylaminoethanol, methylaminoethanol, diethanolamine, N-methyldiethanolamine, triethanolamine, 3-amino-1,2-propanediol, 3-methylamino-1,2-propanediol, 3-dimethylamino-1,2-propanediol, and 1,4-butanediamine.

[0031] The amine compound having an sp2 hybrid orbital that forms the conjugate acid of the amine compound is not particularly limited, but examples thereof include imidazole, N-methylimidazole, 1,2-dimethylimidazole, pyridine, picoline, and lutidine.

[0032] Among these amine compounds that form the conjugate acid of the amine compound, ammonia, ethanolamine compounds, and imidazole compounds are preferred from the viewpoint of availability.

[0033] The quaternary ammonium cation is not particularly limited, but examples thereof include tetramethylammonium cation, tetraethylammonium cation, tetra-n-propylammonium cation, tetra-n-butylammonium cation, tetra-n-hexylammonium cation, etc. Among these, from the viewpoint of availability, tetramethylammonium cation and tetraethylammonium cation are preferred.

[0034] As mentioned above, M +are preferably each independently a hydrogen ion, a Li ion, a Na ion, a K ion, an ammonium ion, a monoethanolammonium ion, a diethanolammonium ion, a triethanolammonium ion, an imidazolium ion, an N-methylimidazolium ion, or a 1,2-dimethylimidazolium ion.

[0035] In the above general formulas (1), (2), and (3), R 2 each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a halogen atom.

[0036] The linear or branched alkyl group having 1 to 6 carbon atoms is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a cyclopentyl group, an n-hexyl group, a 2-ethylbutyl group, a cyclohexyl group, and an n-octyl group.

[0037] The halogen atom is not particularly limited, but includes a fluorine atom, a chlorine atom, a bromine atom, and the like.

[0038] R 2 From the viewpoint of film-forming properties, each of the groups is preferably a hydrogen atom, a methyl group, an ethyl group, or a fluorine atom, more preferably a methyl group, an ethyl group, or a fluorine atom, and even more preferably a methyl group.

[0039] Each m independently represents an integer of 1 to 6, preferably each m independently represents an integer of 1 to 4, more preferably 2.

[0040] Each n is independently 0 or 1, preferably 1.

[0041] The structural unit represented by the general formula (3) represents the doped state of the structural unit represented by the general formula (2). In the conductive polymer of the present invention, during electrolytic oxidation polymerization, some of the structural units represented by the general formula (2) undergo a self-doping reaction and are converted into structural units represented by the general formula (3). This action causes the resulting polymer to exhibit conductivity.

[0042] Dopants that cause an insulator-metal transition through doping can be divided into acceptors and donors. The former enters the vicinity of the polymer chain of a conductive polymer through doping and removes π electrons from the conjugated system of the main chain. As a result, positive charges (holes) are injected into the main chain, and so they are also called p-type dopants. Conversely, the latter donates electrons to the conjugated system of the main chain, and these electrons move through the conjugated system of the main chain, so they are also called n-type dopants.

[0043] The dopant in the present invention is a sulfo group or sulfonate group covalently bonded within the polymer molecule, and is a p-type dopant. Polymers that exhibit conductivity without the addition of an external dopant are called self-doping polymers.

[0044] The thiophene monomer represented by the general formula (1) is not particularly limited, but examples thereof include sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-ethyl-1-propanesulfonate, and sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propyl-1-propanesulfonate. Sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonate, Sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-pentyl-1-propanesulfonate, Sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate, Sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate, 4]dioxin-2-yl)methoxy]-1-isopropyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isobutyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopentyl-1-propanesulfonate, sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-fluoro-1-propanesulfonate sodium propanesulfonate, potassium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid, ammonium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate, or 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate triethylammonium, etc.

[0045] The thiophene monomers exemplified above can be produced using thieno[3,4-b]-1,4-dioxin-2-methanol and a branched sultone compound, which can be synthesized based on a known method (e.g., Journal of Electroanalytical Chemistry, 443, 217-226 (1998)).

[0046] [ka]

[0047] [In the above general formula (4), R 2 is R represented by the above general formula (1) 2 is synonymous with M 2 represents an alkali metal ion (Li ion, K ion, Na ion, Cs ion, etc.). Furthermore, the thiophene monomer represented by the following general formula (4) thus produced can be treated with an acid (contact with an acid or a H ion type cation exchange resin, etc.) to give M 2 can be derived to sulfonic acid (thiophene monomer represented by the above general formula (1)) in which M is a hydrogen atom. 2 The thiophene monomer represented by the above general formula (1) can be obtained by contacting a sulfonic acid in which is a hydrogen atom with an alkali metal compound, ammonia, an amine compound, or a quaternary ammonium compound.

[0048] In the method for producing a conductive polymer solution containing polythiophene of the present invention, a monomer other than the thiophene monomer represented by the above general formula (1) can be used in combination. The monomer is not particularly limited, but examples thereof include thiophene, 3-hexylthiophene, 3,4-ethylenedioxythiophene, hydroxymethyl-3,4-ethylenedioxythiophene, hydroxy-3,4-propyleneoxythiophene, bromomethyl-3,4-ethylenedioxythiophene, N-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethyl)-2-aminoethanesulfonic acid, and N-methyl-N-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethyl)-2-aminoethanesulfonic acid. Examples of suitable thieno[3,4-b][1,4]dioxin-2-ylmethanesulfonic acid include 2,3-dihydrothieno[3,4-][1,4]dioxin-2-ylmethanesulfonic acid, 6-(2,3-dihydrothieno[3,4-][1,4]dioxin-2-yl)-1-hexene, 6-(2,3-dihydrothieno[3,4-][1,4]dioxin-2-yl)-1-hexanesulfonic acid, 6-(2,3-dihydrothieno[3,4-][1,4]dioxin-2-yl)-1-butanesulfonic acid, and O-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-ylmethyl)-4-phenolsulfonic acid.

[0049] The method for producing a conductive polymer solution of the present invention is characterized by including the above steps (i) and (ii), and preferably further includes step (iii).

[0050] Hereinafter, the polymerization step (i) of the present invention will be described, in which at least one pair of electrodes is brought into contact with a solution containing at least a thiophene monomer represented by the general formula (1), a solvent, and an acid, and a potential difference is applied between the electrodes to polymerize the monomer and obtain a polymer.

[0051] In the polymerization step, a monomer containing at least the thiophene monomer represented by the general formula (1) is polymerized. The concentration range of the monomer in the polymerization reaction is not particularly limited, but is preferably 0.1 to 30% by weight, more preferably 0.2 to 20% by weight, more preferably 0.3 to 10% by weight, and even more preferably 0.5 to 8% by weight.

[0052] The "monomer concentration" referred to here is a value expressed as weight of (monomers including thiophene monomers represented by the general formula (1) above) / weight of (monomers including thiophene monomers represented by the general formula (1) above + solvent + acid) × 100 (% by weight).

[0053] The solvent used in the polymerization step is not particularly limited, but is preferably water, a solvent containing water, or a water-soluble solvent, and more preferably water, a water-water-soluble alcohol mixed solvent, or a water-soluble alcohol.

[0054] The water may be, for example, pure water, distilled water, or ion-exchanged water.

[0055] The water-soluble alcohol is not particularly limited, but examples thereof include alcohols such as methanol, ethanol, propanol, and butanol.

[0056] Of these aqueous solvents, water or methanol is preferred, and water is more preferred. The aqueous solvent may be degassed or substituted with an inert gas such as nitrogen.

[0057] The acid used in the polymerization step is not particularly limited, and for example, an inorganic acid or an organic acid can be used. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and boric acid. Examples of organic acids include methanesulfonic acid, paratoluenesulfonic acid, formic acid, acetic acid, lactic acid, and benzoic acid. Among these, sulfuric acid, methanesulfonic acid, and paratoluenesulfonic acid are preferred, and sulfuric acid is more preferred, due to their excellent polymerization reaction rate.

[0058] The solution containing at least a monomer containing a thiophene monomer represented by the following general formula (1), a solvent, and an acid can be produced by mixing these components in any order.

[0059] The amount of acid added (content) is not particularly limited, but the normality of the acid in the starting solution (=molar concentration of acid × valence of the acid) is preferably 0.01 to 10 [N], more preferably 0.01 to 5 [N], and even more preferably 0.01 to 1 [N]. When the starting solution is an aqueous solution, the acid is preferably added (contained) so that the pH of the solution is in the range of 0 to 6.5, more preferably 0 to 5, and even more preferably 0 to 3.

[0060] The method for contacting at least one pair of electrodes with the solution is not particularly limited, but for example, the solution is placed in a container, and an anode and a cathode are immersed in the solution to apply a potential difference. This may be a three-electrode method using a standard electrode, or a two-electrode method. Alternatively, the container itself may be used as an electrode, and a counter electrode may be brought into contact with the solution.

[0061] The potential difference applied between the electrodes is a potential difference that can electrochemically oxidize and polymerize the thiophene monomer represented by the general formula (1) above, and is not particularly limited. However, the potential of the anode determined by the three-electrode method is preferably in the range of 0 to +5 V, more preferably +0.5 to +1.5 V, relative to a silver / silver chloride electrode.

[0062] The material of the container is not particularly limited as long as it is sufficiently durable against the solution, but examples of preferred materials include glass, glass-lined containers, Teflon (registered trademark), polyethylene, polypropylene, polyvinyl chloride, and stainless steel.

[0063] The container may have any shape as long as it can hold the solution inside, and may have a structure in which the anode and cathode can be separated by a porous partition or an ion bridge.

[0064] The electrodes used in the polymerization step can be those that allow an electrochemical oxidation reaction to proceed on their surfaces by applying a potential difference between the electrodes. Examples of the electrodes include, but are not limited to, gold, platinum, nickel, titanium, stainless steel, glassy carbon, and ITO, and these may be used alone or in combination of two or more.

[0065] The reaction pressure in the polymerization step may be any of atmospheric pressure, reduced pressure, and increased pressure.

[0066] The reaction atmosphere in the method for producing polythiophene of the present invention is not particularly limited, and may be an air atmosphere or an inert gas atmosphere such as nitrogen or argon, more preferably an inert gas atmosphere.

[0067] The reaction temperature in the polymerization step is, for example, a temperature at which the thiophene monomer represented by the general formula (1) can be electrochemically oxidatively polymerized, and is not particularly limited, but is preferably in the range of -10 to 150°C, more preferably in the range of 10 to 100°C.

[0068] The reaction time of the polymerization step is not particularly limited, but may be, for example, a time period during which the oxidative polymerization of the thiophene monomer represented by the general formula (1) proceeds sufficiently. Although not particularly limited, the reaction time is preferably in the range of 0.5 to 200 hours, and more preferably in the range of 0.5 to 80 hours.

[0069] The polymerization step can be carried out in a state containing a surfactant in addition to the thiophene monomer represented by the general formula (1) and an aqueous solvent. The addition of the surfactant is preferred in terms of improving the solubility and dispersibility in the aqueous solvent of the thiophene monomer used as a raw material and the thiophene polymer produced.

[0070] The surfactant is not particularly limited, but for example, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc. can be used, and more preferably at least one selected from the group consisting of anionic surfactants and nonionic surfactants.

[0071] The anionic surfactant is not particularly limited, but examples thereof include carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type.

[0072] The carboxylic acid type is not particularly limited, but examples thereof include sodium octanoate, sodium decanoate, sodium palmitate, and sodium stearate.

[0073] The sulfonic acid type is not particularly limited, but examples thereof include sodium hexanesulfonate, sodium decanesulfonate, sodium toluenesulfonate, sodium octylbenzenesulfonate, sodium dodecylbenzenesulfonate, and sodium naphthalenesulfonate.

[0074] The sulfate ester type is not particularly limited, but examples thereof include sodium lauryl sulfate, sodium laureth sulfate, and ammonium lauryl sulfate.

[0075] The phosphate ester type is not particularly limited, but examples thereof include sodium lauryl phosphate and potassium lauryl phosphate.

[0076] The nonionic surfactant is not particularly limited, but examples thereof include polyethylene glycol surfactants, acetylene glycol surfactants, polyhydric alcohol surfactants, and polymeric nonionic surfactants.

[0077] The polyethylene glycol surfactant is not particularly limited, but examples thereof include higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, higher alkylamine ethylene oxide adducts, ethylene oxide adducts of fats and oils, and polypropylene glycol ethylene oxide adducts.

[0078] The acetylene glycol surfactant is not particularly limited, but examples thereof include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, Surfynol (registered trademark, manufactured by Air Products Co., Ltd.), and Olfine (registered trademark, manufactured by Nissin Chemical Industry Co., Ltd.).

[0079] The polyhydric alcohol surfactant is not particularly limited, but examples thereof include fatty acid esters of glycerol, fatty acid esters of pentaerythritol, fatty acid esters of sorbitol and sorbitan, fatty acid esters of sucrose, alkyl ethers of higher alcohols, and fatty acid amides of alkanolamines.

[0080] The polymeric nonionic surfactant is not particularly limited, but examples thereof include polyvinylpyrrolidone and polyvinylpyrrolidone copolymers. The polyvinylpyrrolidone copolymer is not particularly limited, but is preferably one having both a hydrophilic portion and a hydrophobic portion in the polymer chain, such as a copolymer in which polyvinylpyrrolidone is grafted onto polyvinyl alcohol, a vinylpyrrolidone-vinyl acetate block copolymer, a vinylpyrrolidone-methyl methacrylate copolymer, a vinylpyrrolidone-normal butyl methacrylate copolymer, and a vinylpyrrolidone-acrylamide copolymer.

[0081] By carrying out the polymerization reaction as described above, a polymer can be produced, and the polymer is obtained as a polymer solution or a polymer solid. When the polymer is obtained as a polymer solid, all or part of the solid tends to be obtained as a deposit on the anode.

[0082] When the polymer is obtained as a polymer solid, a dissolution step represented by the following (ii) is carried out to obtain a polymer solution.

[0083] Next, (ii) the dissolving step of the present invention, which is carried out when the polymer obtained in the polymerization step is a solid polymer, in which the solid polymer is mixed with a solvent to obtain a polymer solution, will be described.

[0084] If the polymer solid obtained in the polymerization step is precipitated on an electrode, it is preferable that the polymer solid be separated from the electrode in advance. The separation method is not particularly limited, but examples thereof include impact peeling, ultrasonic peeling, peeling using a spatula, and dissolution peeling using a good solvent. Regardless of whether the polymer solid has precipitated on the electrode, it is preferable that the obtained polymer solid be filtered. The filtration method is not particularly limited, but examples include suction filtration, pressure filtration, and natural filtration.

[0085] The filter used to filter the polymer solid may be any filter that can obtain the polymer, and examples thereof include filter paper, membrane filters, and glass filters.

[0086] Next, the polymer solid separated above is mixed with a solvent to obtain a polymer solution.

[0087] The solvent is not particularly limited, but is preferably water, a solvent containing water, or a water-soluble solvent, and more preferably water, a water-water-soluble alcohol mixed solvent, or a water-soluble alcohol.

[0088] The water may be, for example, pure water, distilled water, or ion-exchanged water.

[0089] The water-soluble alcohol is not particularly limited, but examples thereof include alcohols such as methanol, ethanol, propanol, and butanol.

[0090] Of these aqueous solvents, water, a water-methanol mixed solvent, or methanol is preferred, and water is more preferred. The aqueous solvent may be degassed or purged with an inert gas such as nitrogen.

[0091] The polymer concentration in the polymer solution is not particularly limited, but is preferably in the range of 0.01 to 20% by weight. From the viewpoint of excellent processing efficiency in the next step (iii), the polymer concentration is preferably 0.1 to 10% by weight, and more preferably 0.2 to 5% by weight.

[0092] The viscosity of the polymer solution is preferably in the range of 0.1 to 1000 mPa·s.

[0093] The polymer solution thus produced in step (i) or step (ii) is a conductive polymer solution characterized by a low iron content, which is the objective of the present invention, and such steps make it possible to produce the conductive polymer solution that is the objective of the present invention.

[0094] Next, the anion exchange step (iii), in which the polymer solution obtained in the polymerization step or dissolution step is brought into contact with an anion exchange resin to exchange the anions in the polymer solution for hydroxide ions, will be described.

[0095] The anion exchange resin is not particularly limited, but examples thereof include weakly basic anion exchange resins and strongly basic anion exchange resins, and weakly basic anion exchange resins are preferred because they are excellent in efficiently increasing the purity of the polymer.Furthermore, the weakly basic anion exchange resin is not particularly limited, but an amine-type weakly basic anion exchange resin is preferred. As the amine-type weakly basic anion exchange resin, commercially available products can be used, and although not particularly limited, for example, DIAION (registered trademark) WA20, DIAION (registered trademark) WA21, DIAION (registered trademark) WA30 (manufactured by Mitsubishi Chemical Corporation), AMBERLITE (registered trademark) IRA67, AMBERLITE (registered trademark) IRA96SB, AMBERLITE (registered trademark) IRA98 (manufactured by Organo Corporation), DOWEX (registered trademark) 66 (manufactured by Dow), DUOLITE A368MS (manufactured by Rohm and Haas), LEWATIT (registered trademark) MP62WS, LEWATIT (registered trademark) Monoplus MP64, etc. can be suitably used.

[0096] The obtained conductive polymer solution can be further subjected to other operations such as purification, viscosity adjustment, or component adjustment to prepare a conductive polymer solution suitable for the intended use.

[0097] The other purification method is not particularly limited, but may include, for example, ultrafiltration.

[0098] The viscosity adjustment method is not particularly limited, but examples thereof include a method of removing the solvent by ultrafiltration or distillation, and a method of adding a solvent. When a solvent is added, the solvent is not particularly limited, but examples thereof include the same solvents as those used in the polymerization step, and water is more preferred.

[0099] The aforementioned component adjustment is not particularly limited, but may involve adding a conventionally known additive that is generally used in the field of conductive polymer compositions based on a conventionally known method.

[0100] The conductive polymer aqueous solution produced by the above-mentioned production method is characterized by containing a polythiophene containing at least two or more repeating structures selected from the group consisting of the repeating structure represented by the general formula (2) and the repeating structure represented by the general formula (3), and further characterized by a low iron ion content. Because the iron ion content is low, the production method of the present invention does not require the purification operation by a cation exchange step that was commonly performed in conventional techniques, thereby reducing the number of steps and achieving the effect of reducing the environmental burden.

[0101] It should be noted that the conductive polymer solution is desired to have a low iron ion content when applied to its intended use, and the iron content is preferably 10 ppm or less, more preferably 5 ppm or less, more preferably 2 ppm or less, even more preferably 0.5 ppm or less, and still more preferably 0.2 ppm or less. [Example]

[0102] The present invention will now be described in detail with reference to examples, but the present invention should not be construed as being limited to these examples.

[0103] (Iron ion content measurement method) The amount of iron ions in the conductive polymer solution was measured by the internal standard method using inductively coupled plasma atomic emission spectrometry (ICP-AES) on an Optima 8300 manufactured by PerkinElmer.

[0104] (Conductivity measurement method) The conductive polymer solution was cast onto a 5 cm square glass substrate that had been treated with UV / O3, and then dried at 120°C to form a film containing the conductive polymer. This was then heat-treated at 150°C for 1 hour. The thickness and surface electrical resistance of the resulting film were measured, and the conductivity was calculated using the following formula:

[0105] Conductivity [S / cm]=10 4 / (Surface resistivity [Ω / □]×film thickness [μm]) (Molecular weight measurement method) Apparatus: Tosoh GPC8020 Column: TSKGel α-M + guard column α Detector: UV-8020 (335 nm) Eluent: dimethyl sulfoxide / 10mM-LiBr Detection temperature: 50℃ Flow rate: 0.6mL / min Injection volume: 20μL (approx. 1000ppm) Standard sample: pullulan Sample preparation method: 1.2 g of a 50 wt % diisopropylamine / methanol solution was added to 2 g of a conductive polymer aqueous solution (solid content = 0.7 wt %) and stirred overnight at room temperature. The resulting solution was concentrated to dryness to obtain a deep purple solid. 25 mL of dimethyl sulfoxide, a polar organic solvent, was added to 25 mg of the solid and allowed to stand overnight. The solution was then filtered through a 0.45 μm syringe filter to prepare an analytical sample.

[0106] Example 1 (Polymerization Method) Polymerization was carried out at 25°C using a standard three-electrode cell. The working and counter electrodes were platinum plates (2.0 cm x 2.5 cm), and the standard electrode was a silver / silver chloride electrode. 0.50 g of sodium 3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-2-methyl-1-propanesulfonate (a thiophene monomer represented by the general formula (5) below) was placed in the cell, and 30 g of purified water and 8.7 g of 44% sulfuric acid were added. The solution was then stirred for 5 minutes to dissolve the monomer. The monomer concentration at this point was 1.3 wt%. The pH of the solution was 0.5. The electrodes were then attached to the cell, and a potential of +1.1 V relative to the standard electrode was applied to the working electrode for 2 hours, resulting in the deposition of a deep ultramarine solid on the working electrode. The precipitate was polythiophene (a polymer containing repeating units represented by the following general formula (6) and the following general formula (7)) formed by polymerization of the thiophene monomer.

[0107] [ka]

[0108] [ka]

[0109] [ka]

[0110] (Purification of polymer) A polymer containing polythiophene (a polymer containing repeating units represented by the general formulas (6) and (7)) deposited on the anode by electrochemical oxidative polymerization was separated from the anode and recovered by filtration. Next, 16 g of pure water was added to the resulting polymer, and the mixture was stirred and then homogenized for 15 minutes using an ultrasonic homogenizer to obtain a polymer solution. The polymer solution was passed through an anion exchange resin (LEWATIT (registered trademark) MP62WS) to obtain a deep ultramarine aqueous solution (conductive polymer solution) containing 1.3 wt% polythiophene (a polymer containing repeating units represented by the general formulas (6) and (7)).

[0111] (iron ion content) Using the above method, the amount of iron ions contained in an aqueous solution containing polythiophene (a polymer containing repeating units represented by the following general formula (6) and the following general formula (7)) at a concentration of 1.3 wt % was measured. As a result, the iron ion content was 0.19 ppm.

[0112] (conductivity) The conductivity of the resulting conductive polymer was measured by the above-mentioned conductivity measurement method and was found to be 150 S / cm.

[0113] (molecular weight) The molecular weight of the resulting conductive polymer was measured by the above-mentioned molecular weight measurement method, and the weight average molecular weight was found to be 4,755.

[0114] Example 2 The same polymerization procedure as in Example 1 was carried out, except that the voltage application time was changed from 2 hours to 1 hour, and then the same purification procedure of the polymer as in Example 1 was carried out to obtain a deep ultramarine aqueous solution (conductive polymer solution) containing a concentration of 1.0 wt% polythiophene (a conductive polymer, a polymer containing repeating units represented by the above general formula (6) and the above general formula (7)). The pH of the charged solution was 0.5.

[0115] (iron ion content) Using the above method, the amount of iron ions contained in an aqueous solution containing a 1.0 wt% concentration of polythiophene (a polymer containing repeating units represented by the following general formula (6) and the following general formula (7)) was measured. As a result, the iron ion content was 0.19 ppm.

[0116] (conductivity) The conductivity of the resulting conductive polymer was measured by the above-mentioned conductivity measurement method and was found to be 122 S / cm.

[0117] (molecular weight) The molecular weight of the resulting conductive polymer was measured by the above-mentioned molecular weight measurement method, and the weight average molecular weight was found to be 4,709.

[0118] Example 3 The same polymerization procedures as in Example 1 were carried out, except that in Example 1, the amount of sodium 3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-2-methyl-1-propanesulfonate (a thiophene monomer represented by the following general formula (5)) was changed from 0.50 g to 1.0 g, the amount of pure water was changed from 30 g to 63 g, and 8.7 g of 44% sulfuric acid was changed to 15 g of paratoluenesulfonic acid (the monomer concentration at this time was 1.3 wt %. The pH of the charged solution was 0.34), and the application of a potential of +1.1 V for 75 minutes was changed from 2 hours to 75 minutes, thereby obtaining a deep ultramarine aqueous solution (conductive polymer solution) containing polythiophene (a polymer comprising repeating units represented by the above general formulas (6) and (7) above, which is a conductive polymer).

[0119] Example 4 The same polymerization procedures as in Example 1 were carried out, except that the amount of pure water was changed from 30 g to 35 g, 8.7 g of 44% sulfuric acid was changed to 4.1 g of 35% hydrochloric acid (the monomer concentration at this time was 1.3 wt %. The pH of the charged solution was 0.47), and the application of a potential of +1.1 V for 10 minutes was changed from 2 hours, to obtain a deep ultramarine aqueous solution (conductive polymer solution) containing polythiophene (a polymer comprising repeating units represented by the above general formula (6) and the above general formula (7), which is a conductive polymer).

[0120] Example 5 The same polymerization procedures as in Example 1 were carried out, except that the amount of pure water was changed from 30 g to 36 g, and that 8.7 g of 44% sulfuric acid was changed to 2.6 g of phosphoric acid (the monomer concentration at this time was 1.3 wt %. The pH of the charged solution was 1.2). This resulted in a deep ultramarine aqueous solution (conductive polymer solution) containing polythiophene (a polymer comprising repeating units represented by the above general formula (6) and the above general formula (7), which is a conductive polymer).

[0121] Example 6 The same polymerization procedures as in Example 1 were carried out, except that the amount of pure water was changed from 30 g to 31 g, 8.7 g of 44% sulfuric acid was changed to 7.5 g of methanesulfonic acid (the monomer concentration at this time was 1.3 wt %. The pH of the charged solution was 0.25), and the application of a potential of +0.95 V for 10 minutes was changed from the application of a potential of +1.1 V for 2 hours, to obtain a deep ultramarine aqueous solution (conductive polymer solution) containing polythiophene (a conductive polymer, a polymer containing repeating units represented by the above general formula (6) and the above general formula (7)).

[0122] Example 7 The same polymerization procedures as in Example 1 were carried out, except that the amount of pure water was changed from 30 g to 31 g, 8.7 g of 44% sulfuric acid was changed to 8.2 g of 60% nitric acid (the monomer concentration at this time was 1.3 wt %. The pH of the charged solution was 0.13), and the application of a potential of +1.1 V for 2 hours was changed to the application of a potential of +0.95 V for 10 minutes, thereby obtaining a deep ultramarine aqueous solution (conductive polymer solution) containing polythiophene (a polymer comprising repeating units represented by the above general formula (6) and the above general formula (7), which is a conductive polymer).

[0123] Example 8 The same equipment as in Example 1 was used. 0.50 g of sodium 3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-2-methyl-1-propanesulfonate (a thiophene monomer represented by the following general formula (5)) was placed in a cell, and 34 g of pure water and 4.7 g of acetic acid were added. The mixture was then stirred for 5 minutes to dissolve the monomer (the monomer concentration at this stage was 1.3 wt %. The pH of the starting solution was 2.3). Next, an electrode was attached to the cell, and a potential of +1.4 V relative to the standard electrode was applied to the working electrode for 2 hours to obtain a deep ultramarine solid precipitated on the working electrode and a deep ultramarine solution. Both the deep ultramarine solid and the deep ultramarine solution contained polythiophene (a polymer containing repeating units represented by the above general formulas (6) and (7)) formed by polymerization of the thiophene monomer.

[0124] Example 9 A 50 mL beaker was charged with 0.50 g of sodium 3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-2-methyl-1-propanesulfonate (a thiophene monomer represented by the following general formula (5)). 36 g of methanol and 2.0 g of methanesulfonic acid were added, followed by stirring for 5 minutes to dissolve the solution. Next, a pair of platinum plates (2.0 cm x 2.5 cm) were attached to the beaker as electrodes. A DC power supply was connected to the electrodes, and a potential of +1.0 V was applied for 10 minutes to obtain a reddish-purple solution. This solution was stirred overnight in an air atmosphere to obtain a blue solution. The solution contained polythiophene (a polymer containing the repeating units represented by the above general formulas (6) and (7)) polymerized from the thiophene monomer.

[0125] [Table 1]

[0126] Reference example 1 A 500 mL separable flask was charged with 10 g (30 mmol) of sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate (a thiophene monomer represented by the general formula (5) above) and 150 g of water. After dissolution, 2.94 g (18.1 mmol) of anhydrous iron(III) chloride was added at room temperature and stirred for 20 minutes. A mixed solution consisting of 14.5 g (60.4 mmol) of sodium persulfate and 100 g of water was then added dropwise while maintaining the reaction solution temperature at 30°C or below. After stirring at room temperature for 3 hours, the reaction solution was added dropwise to 800 g of acetone to precipitate a black Na-type polymer. The polymer was filtered and dried under vacuum to obtain 18.0 g of crude polymer of sodium 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate.

[0127] Next, 14.5 g of this crude polymer was added to water to prepare a 725 g aqueous solution with a solids content of 2 wt%. 700 g of this solution was passed through a column packed with 200 mL of cation exchange resin Lewatit Mono Plus S100 (H-type) (space velocity = 1.1), yielding 738 g of an H-type aqueous polymer solution. This aqueous polymer solution was further purified by cross-flow ultrafiltration (filter = Vivaflow 200, molecular weight cutoff = 5,000, permeability = 5) to yield 698 g of a deep ultramarine aqueous solution containing polythiophene (a polymer containing repeating units represented by the above general formulas (6) and (7)). The polymer amount (solid content) in the polythiophene aqueous solution was 0.74 wt%. Furthermore, ICP-MS analysis revealed that the polythiophene aqueous solution contained 44 ppm of iron ions based on the solids content. That is, the polythiophene aqueous solution (conductive polymer aqueous solution) contained 0.32 ppm of iron ions. [Industrial Applicability]

[0128] The method for producing a conductive polymer solution of the present invention can produce a conductive polymer solution with a low iron ion content equivalent to that of conventional solutions, without performing a cation exchange operation. The conductive polymer solution obtained by the production method of the present invention is expected to be applicable to organic electroluminescence (EL) displays, LCDs, capacitors, antistatic agents, etc.

Claims

1. A repeating structure represented by the following general formula (2) and a repeating structure represented by the following general formula (3) 【Chemical 1】 【Chemistry 2】 [In the above general formula (2), M ＋ Each of R independently represents a hydrogen ion, an alkali metal ion, an ammonium ion, an organic ammonium ion, or a quaternary ammonium cation. ２ represents a linear or branched alkyl group having 1 to 6 carbon atoms, m represents an integer of 1 to 6, and n represents 0 or 1. A method for producing a conductive polymer solution containing polythiophene having at least two or more repeating structures selected from the group consisting of repeating structures represented by the following formula: (i) a polymerization step of bringing at least one pair of electrodes into contact with a solution containing at least a thiophene monomer represented by the following general formula (1), a solvent, and an acid, and applying a potential difference between the electrodes to polymerize the monomer, thereby obtaining a polymer solid or a polymer solution; (ii) a dissolving step in which, when the polymer obtained in the polymerization step is a polymer solid, the polymer solid is mixed with a solvent to obtain a polymer solution; A method for producing a conductive polymer solution, comprising: 【Chemistry 3】 [In the above general formula (1), M ＋ represents a hydrogen ion, an alkali metal ion, an ammonium ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. ２ represents a linear or branched alkyl group having 1 to 6 carbon atoms, m represents an integer of 1 to 6, and n represents 0 or 1.

2. The above R ２ The method according to claim 1 , wherein is a methyl group.

3. 3. The method according to claim 1, wherein the concentration of the monomer in the polymerization step is 0.1 to 30% by weight.

4. 4. The method according to claim 1, wherein in the polymerization step, when the charged solution is an aqueous solution, its pH is in the range of 0 to 6.

5.

5. 5. The method according to claim 1, wherein the potential applied to the anode in the polymerization step is in the range of 0 to +5 V relative to a silver / silver chloride electrode.

6. The manufacturing method according to any one of claims 1 to 5, (iii) an anion exchange step of contacting the polymer solution obtained in the polymerization step or dissolution step with an anion exchange resin to exchange the anions in the polymer solution with hydroxide ions; The manufacturing method further comprises:

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