JP2007051247A - Method for preparing electroconductive polymer solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing an electroconductive solution which can obtain an electroconductive polymer soluble in general-purpose organic solvents, excellent in electroconductivity, and excellent in dissolution stability as well. <P>SOLUTION: The method for preparing an electroconductive polymer solution comprises dissolving component (A) of a compound in which at least one sulfonic acid functional group of a sulfonic acid group and a sulfonic acid salt group is bound with a benzene ring or a naphthalene ring and is soluble in a solvent containing a solvent having a solubility parameter of 8.0-10.0 as the major component in the above solvent, thereafter adding component (B) of a monomer composed of at least one of aniline and an aniline derivative having an alkyl group or an oxyalkyl group and component (C) of a 0.3-3.0 N acid, emulsifying them to introduce a sulfonic acid structure derived from the monomer of the above component (A) into the monomer of the above component (B), and then polymerizing the monomer of the above component (B) into which this sulfonic acid structure has been introduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a conductive polymer solution. Specifically, in various fields such as electricity, electronics, and materials, the surface of a polymer material is made conductive, various types of insulating materials are made conductive, or metal materials are made. The present invention relates to a method for producing a conductive polymer solution useful for surface coating and the like.

  In general, aromatic conductive polymers such as polyaniline, polyphenylene, polythiophene, and polypyrrole are attracting attention because of their excellent stability in the air and easy synthesis. For example, among these conductive polymers, polyaniline is practically used as a positive electrode material for secondary batteries because it is particularly excellent in stability in air and is an inexpensive material.

  However, conventionally, an aromatic conductive polymer such as polyaniline is insoluble and infusible in a solvent, and therefore has poor moldability, and its application field has been limited. For this reason, realization of a conductive polymer having good solubility has been demanded.

  Therefore, the present inventor has found that polyaniline obtained by polymerizing aniline having a surfactant structure is soluble in water or an organic solvent, and has already filed a patent application for this polyaniline (Patent Document 1). reference).

  However, as a result of further studies by the present inventors, the polyaniline is sufficient for the demand for dispersibility (solubility) in a ketone solvent such as methyl ethyl ketone (MEK) and an aromatic solvent such as toluene. It was found that it was difficult to achieve a uniform solution as required without being able to respond.

Accordingly, the present inventor has conducted intensive research to solve these problems, and as a result, the present inventors have obtained a solution of a conductive polyaniline having a surfactant structure, and the interface used to form the surfactant structure. It has been found that the activator can solve the above problem by a solution of conductive polyaniline having a repeating structure of alkylene ether in the molecular structure, and such a conductive polyaniline solution has been filed for a patent earlier (see Patent Document 2). ).
Japanese Patent Laid-Open No. Hei 6-279594 JP 2003-277500 A

  However, as a result of further research on the conductive polyaniline solution described in Patent Document 2, it is found that if the conductive polyaniline solution is left for a predetermined time, for example, about one week, a precipitate of polyaniline tends to be generated. I found it. The polyaniline that causes this precipitation is somewhat difficult to re-dissolve, and therefore, conductive polyaniline tends to be slightly inferior in its dissolution stability.

  The present invention has been made in view of such circumstances, and is a conductive polymer solution that is soluble in a general-purpose organic solvent and that can provide a conductive polymer that is excellent in conductivity and also in dissolution stability. The purpose is to provide a manufacturing method.

In order to achieve the above object, the method for producing a conductive polymer solution of the present invention includes the following component (A) in a solvent mainly composed of a solvent having a solubility parameter of 8.0 to 10.0. After dissolution, the component (B) and the component (C) are added and emulsified to introduce the sulfonic acid structure derived from the component (A) into the monomer of the component (B). The monomer (B) having an acid structure introduced therein is polymerized.
(A) A compound soluble in the above-mentioned solvent, wherein at least one sulfonic acid functional group of a sulfonic acid group and a sulfonic acid group is bonded to a benzene ring or a naphthalene ring.
(B) A monomer comprising aniline and at least one of an aniline derivative having an alkyl group or an oxyalkyl group.
(C) 0.3-3.0N acid.

That is, the present inventors have conducted extensive research in order to obtain a conductive polymer that is soluble in a general-purpose organic solvent, excellent in conductivity, and excellent in dissolution stability. And after dissolving a specific compound beforehand in the specific solvent which has a solvent whose solubility parameter is 8.0-10.0 as a main component, at least one monomer of aniline and a specific aniline derivative is specified. It was recalled that a concentration of acid was added and these were stirred and emulsified. In this way, the sulfonic acid structure of the specific compound is introduced (doping) into the specific monomer, and then the monomer having the sulfonic acid structure introduced (doping) is polymerized to obtain the specific compound. It is thought that the part derived from the above (part composed of the above compound) is strongly bonded (ionic bond) to the ionic part of the polymer (conductive polymer) of the monomer via the sulfonate ion. It is done. That is, an ionic moiety such as “—NH ⁺ ” of a polymer of a monomer such as aniline (polyaniline or the like) and the “SO ₃ ⁻ ” ion of the sulfonic acid functional group of the above compound are ionically bonded to form polyaniline or the like. It is considered that the above compound is firmly bonded. As a result, the obtained conductive polymer is excellent in dissolution stability, soluble in an organic solvent, and excellent in conductivity. Moreover, even when it is left in a humid heat (high humidity and high temperature) environment, there is almost no aggregation phenomenon of the conductive polymer due to the strong bond (ionic bond), and there is little change in electrical resistance in the humid heat environment, It also has excellent stability in a humid heat environment.

  As described above, according to the method for producing a conductive polymer solution of the present invention, a portion derived from the specific compound is strongly bonded to an ionic portion of the polymer (conductive polymer) of the monomer via a sulfonate ion. It is thought that it becomes bound (ion bond). As a result, the obtained conductive polymer is excellent in dissolution stability, soluble in an organic solvent, and excellent in conductivity. Moreover, even when it is left in a moist heat environment, the above-mentioned strong bond (ionic bond) hardly causes a cohesive phenomenon of the conductive polymer, and there is little change in electrical resistance in the moist heat environment, and the stability in the moist heat environment. It will also be excellent in performance. In addition, since the conductive polymer solution obtained by the manufacturing method of the present invention can dissolve the conductive polymer with a small amount of organic solvent, for example, when a conductive thin film is produced using this conductive polymer solution, the organic solvent There are advantages such as shortening the drying time, enabling thick coating, and blending with other polymers.

  The specific compound (component A) has at least one sulfonic acid functional group of a sulfonic acid group and a sulfonic acid group and a lipophilic component, and has a number average molecular weight in the range of 368 to 30,000. When it is a compound (surfactant, compatibilizer, etc.), it becomes easy to maintain solubility in a solvent, and it is easy to form a strong bond (ionic bond) with the above monomer (component B). Environmental stability is further improved.

  And when the mixing ratio of said acid (C component) is the range of 1.0-30.0 mol with respect to 1 mol of said monomers (B component), said specific compound (A component) and The ionic bond with the polymer of the above monomer (component B) becomes strong, and the stability in a humid heat environment becomes excellent.

  Further, when the solubility of the specific compound (component A) in the solvent is 15% or more, the solubility of the conductive polymer obtained by the production method of the present invention is increased, thick coating is possible, and the drying time is reduced. Shortening is also possible.

  Further, when the solvent having the solubility parameter of 8.0 to 10.0 is at least one of an aromatic solvent and a ketone solvent, the solubility in the specific compound (component A) is high. The emulsification at the time of mixing and stirring the above acid (C component) becomes fine, so that uniform and strong sulfonic acid groups can be introduced and a uniform polymerization reaction can be achieved.

  Next, an embodiment of the present invention will be described.

The method for producing a conductive polymer solution of the present invention is obtained by dissolving the following component (A) in a solvent whose main component is a solvent having a solubility parameter of 8.0 to 10.0, (C) component is added, these are emulsified and the sulfonic acid structure derived from the said (A) component is introduce | transduced in the monomer of the said (B) component, Then, this (B ) Component monomer is polymerized.
(A) A compound soluble in the above-mentioned solvent, wherein at least one sulfonic acid functional group of a sulfonic acid group and a sulfonic acid group is bonded to a benzene ring or a naphthalene ring.
(B) A monomer comprising aniline and at least one of an aniline derivative having an alkyl group or an oxyalkyl group.
(C) 0.3-3.0N acid.

  In the present invention, a solvent whose main component is a solvent having a solubility parameter of 8.0 to 10.0 is used, and a specific compound (component A) is used as a dopant and dissolved in advance, and a specific acid (C Component A) is used in combination, and the A component is efficiently doped mainly at the time of polymerization of the monomer (B component), and these are the greatest features.

  Here, the main component means that the solvent having the above solubility parameter occupies at least 60% by weight of the entire solvent excluding the C component, and the entire solvent is occupied by the solvent having the above parameter. Also good.

  In the present invention, the sulfonic acid functional group is selected from the group consisting of a sulfonic acid group and a sulfonic acid base (a sulfonic acid metal base such as sodium sulfonate and potassium sulfonate, and an ammonium sulfonate base). And at least one functional group. The sulfonic acid functional group forms a sulfonic acid structure (sulfonic acid metal salt structure, ammonium sulfonate structure, etc.) in the introduced monomer.

  The specific compound (component A) preferably has a sulfonic acid functional group amount in the range of 0.3 to 2.3 mmol / g, particularly preferably in the range of 0.5 to 2.0 mmol / g. That is, when the amount of the sulfonic acid functional group of the compound (component A) is less than 0.3 mmol / g, it becomes difficult to introduce the sulfonic acid structure into the monomer (component B). This is because the stability effect tends to deteriorate, and only the monomer (component B) tends to polymerize and precipitate. Conversely, if the amount of the sulfonic acid functional group of the above compound (component A) exceeds 2.3 mmol / g, the solubility in the solvent tends to decrease.

  The amount of the sulfonic acid functional group is measured by, for example, burning the above compound (component A) in a flask, obtaining the amount of sulfur element by ion chromatography, and converting this as the amount of sulfonic acid functional group. Can be sought.

  In the present invention, the above compound (component A) is soluble in a solvent. The above compound (component A) with respect to a solvent whose main component is a solvent having a solubility parameter of 8.0 to 10.0. The solubility is 10% or more, preferably 15% or more, and particularly preferably 30% or more. That is, when the solubility is less than 10%, the emulsified state at the time of polymerization becomes non-uniform or the solubility of the conductive polymer obtained by polymerization in the solution deteriorates.

  As the compound (component A), a compound soluble in the above solvent in which at least one sulfonic acid functional group of a sulfonic acid group and a sulfonic acid group is bonded to a benzene ring or a naphthalene ring is used. Often used as an activator or compatibilizer.

  Examples of the surfactant include polyoxyalkylene alkyls containing at least one benzenesulfonic acid (salt), naphthalenesulfonic acid (salt), ether group, etc. containing at least one long-chain alkyl group having 4 to 18 carbon atoms. And phenyl ether sulfonic acid (salt).

  Moreover, as said surfactant, specifically, the alkylbenzenesulfonic acid sodium salt represented by following formula (1) is preferable.

  In addition, the compound (component A) preferably has at least one alkyl substituent, and the total number of carbon atoms of the alkyl substituent is 15 to 25.

  The number average molecular weight (Mn) of the above compound (component A) is preferably in the range of 368 to 30,000, particularly preferably in the range of 400 to 3,000. That is, when the number average molecular weight (Mn) of the above compound (component A) is less than 368, the solubility in a solvent tends to be reduced, and conversely when it exceeds 30,000, the monomer (component B) This is because it tends to be difficult to introduce a sulfonic acid structure into the polymer, or to make uniform polymerization difficult due to thickening during synthesis.

  Next, in the present invention, a monomer (component B) comprising at least one of aniline and an aniline derivative having an alkyl group or an oxyalkyl group is used together with the above compound (component A).

  The aniline derivative is not particularly limited as long as it has an alkyl group or an oxyalkyl group as a substituent on the benzene ring of aniline, preferably an alkyl group having 1 to 2 carbon atoms or an oxyalkyl group, particularly preferably. It is a C1-C1 alkyl group or oxyalkyl group. Examples of the specific aniline derivative include o-anisidine, o-toluidine, 2-ethylaniline, methoxyaniline, m-anisidine, m-toluidine and the like. These may be used alone or in combination of two or more.

  The mixing ratio (molar ratio) between the compound (component A) and the monomer (component B) is preferably in the range of component A / component B = 1 / 0.5 to 1 / 20.0. Preferably, A component / B component = 1 / 5.0 to 1 / 15.0. In addition, A component calculates the molecular weight (molar equivalent) with respect to one sulfonic acid group as 1 mol.

  The acid (component C) used together with the compound (component A) and the monomer (component B) is not limited as long as it is used according to the definition of Arrhenius, Bronsted Raleigh, Lewis. , Hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, boron compounds, compounds having a p-benzoquinone structure such as chloranil (tetrachloro-p-benzoquinone), and the like. These may be used alone or in combination of two or more.

  The concentration of the acid (component C) is not particularly limited as long as it is in the range of 0.3 to 3.0N, but is preferably in the range of 0.5 to 2.0N. That is, if the concentration of the acid (C component) is less than 0.3 N, it is difficult to introduce a sulfonic acid structure into the specific monomer (B component). This is because decomposition of the compound (component A) occurs or it is difficult to increase the molecular weight as a conductive polymer.

The mixing ratio of the acid (C component) is preferably in the range of 1.0 to 30.0 mol, particularly preferably 12.0 to 25. mol, per 1 mol of the specific monomer (component B). Within the range of 0 mole. As a mixing method, the whole amount of the acid may be mixed with the monomer before the polymerization, or the acid may be divided and mixed according to the progress of the polymerization.

  The specific solvent used in the process for producing the conductive polymer solution of the present invention is mainly composed of a solvent having a solubility parameter (SP value) of 8.0 to 10.0.

Here, the solubility parameter (SP value) is synonymous with a solubility parameter (solubility parameter), and is a characteristic value of a liquid that is a measure of the mixing property between liquids. When the SP value is δ, the molecular cohesive energy of the liquid is E, and the molecular volume is V, δ = (E / V) ^1/2 .

  The specific solvent is not particularly limited as long as it is mainly composed of a solvent having an SP value of 8.0 to 10.0 as described above, and the SP value is 8.0 to 10.0. One solvent or a mixture of two or more may be used. The specific solvent is preferably composed of only the solvent (x) having an SP value of 8.0 to 10.0, but the solvent (x) having an SP value of 8.0 to 10.0 It is also possible to mix with a solvent (y) having an SP value of less than 8.0 or an SP value of more than 10. In this case, the ratio of the solvent (y) is preferably less than 30% by weight of the entire specific solvent (mixed solvent). That is, when the proportion of the solvent (x) having an SP value of 8.0 to 10.0 is too small, the solubility of the specific compound (component A) is poor, and the specific monomer (component B) is not doped. This is because it does not happen efficiently. Examples of the solvent (y) include n-hexane (SP value: 7.3), n-butanol (SP value: 11.4), N-methyl-2-pyrrolidone (NMP) (SP value: 11.2), dimethyl sulfoxide (SP value: 12.8), N, N-dimethylformamide (SP value: 11.5) and the like.

  The solvent having the SP value of 8.0 to 10.0 is not particularly limited, and examples thereof include aromatic solvents, ketone solvents, ester solvents, ether solvents, and the like. Two or more types are used in combination. As the solvent having an SP value of 8.0 to 10.0, at least one of an aromatic solvent and a ketone solvent is preferably used, and the mixing ratio when both are mixed is particularly limited. is not.

  Examples of the aromatic solvent include toluene (SP value: 8.9), xylene (SP value: 8.8), and the like. Examples of the ketone solvent include MEK (SP value: 9.3), acetone (SP value: 10), methyl isobutyl ketone (SP value: 8.4), cyclohexanone (SP value: 9.9), and the like. can give. Examples of the ester solvent include ethyl acetate (SP value: 9.1) and butyl acetate (SP value: 8.5). Examples of the ether solvent include tetrahydrofuran (THF) (SP value: 9.5), ethyl cellosolve (SP value: 9.9), butyl cellosolve (SP value: 8.9), and the like.

  Here, the production method of the conductive polymer solution of the present invention will be specifically described. That is, a specific solvent mainly comprising a solvent having a solubility parameter (SP value) of 8.0 to 10.0, preferably at least one solution of an aromatic solvent such as toluene and a ketone solvent such as MEK. Prepare. Next, the above compound (component A) is dissolved in the specific solvent, and a predetermined amount of each of the monomer (component B) and the acid (component C) is added, and a predetermined temperature (preferably Is adjusted to −10 to 30 ° C.). Next, this solution is stirred and emulsified while maintaining a predetermined temperature (preferably 2 to 10 ° C.), and a sulfonic acid structure derived from the compound (A component) is introduced into the monomer (B component). To do. Next, a predetermined amount of a chemical oxidizing agent such as ammonium persulfate is added, and a polymerization reaction is performed for a predetermined time (preferably, 10 to 25 hours), whereby a target conductive polymer solution can be obtained.

  In addition, after adding a poor solvent such as water or methanol to the conductive polymer solution to remove unreacted substances, chemical oxidants, decomposition products thereof, etc. (washing), a high-purity conductive polymer is obtained. When this is dissolved in a solvent such as an aromatic solvent, ketone solvent, ether solvent, etc., it is left standing or centrifuged, and purified by suction filtration to remove the insoluble matter. A polymer solution can be obtained.

  In the production method of the present invention, ammonium persulfate was used as the chemical oxidant. However, the present invention is not limited to this. A peroxide such as hydrogen peroxide or benzoyl peroxide, a benzoquinone such as chloranil, a second chloride. It is also possible to use a known oxidizing agent such as iron.

  The conductive polymer solution obtained by the production method of the present invention is excellent in solution stability because it is kept in a uniform solution without aggregation even after being left for about one week. Further, as described above, the conductive film (coating film) produced from the conductive polymer solution obtained by the production method of the present invention is allowed to stand for about 10 days in a moist heat environment, for example, by strong bonding (ionic bonding). However, almost no aggregation phenomenon of the conductive polymer is observed in the coating film, the change in electric resistance in the wet heat environment is small, and the stability in the wet heat environment is excellent.

  The number average molecular weight (Mn) of the conductive polymer (main chain portion) obtained by the production method of the present invention is preferably in the range of 500 to 100,000, particularly preferably in the range of 1,000 to 20,000. .

  The conductive polymer solution obtained by the production method of the present invention can be produced by, for example, a Langmuir Blodget (LB) film formation method, a spin coating method, a spray coating method, an ink jet method, a dip method, a centrifugal molding method, or the like. Is possible. It is also possible to form micelles and co-vesicles together with amphiphiles (surfactants) that form micelles and vesicle structures to form polymer composites.

In addition, a conductive polymer solution obtained by the production method of the present invention was applied on a SUS plate and dried to prepare a coating film having a thickness of 20 μm, and then a voltage of 10 V was applied in an environment of 25 ° C. × 50% RH. When the electrical resistance of the coating film when applied is measured according to JIS K 7194, the electrical resistance is preferably within the range of 1 × 10 ⁻² to 1 × 10 ¹⁰ Ω · cm, particularly preferably 1 ×. It is in the range of 10 ⁰ to 1 × 10 ⁶ Ω · cm.

  In addition, the conductive polymer solution obtained by the production method of the present invention may be used alone or as a composite mixed with other resins, rubbers, paints, and inorganic materials, and its processability and electrical property stability It is particularly useful in various fields such as electricity, electronics, and materials, which are fields that make the best use of. Specifically, antistatic coating agents, rollers, belts, blade members, fiber treatment agents, antistatic materials for automobile fuel hoses, secondary batteries used in printers and copiers for electrophotographic equipment, etc. Cathode materials, organic thin-film solar cells and dye-sensitized solar cell electrodes and active layer materials, anti-corrosion paints, electromagnetic shielding materials, ID tag antenna materials, polymer actuators, supercapacitor electrode materials, organic EL materials, It can be used for a semiconductor of an organic transistor.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples.

[Example 1]
(Preparation of conductive polymer)
In 4500 ml of methyl ethyl ketone (SP value: 9.3), dinonylnaphthalenesulfonic acid represented by the following formula (2) (Mn: 460.7, sulfonic acid group amount: 2.2 mmol / g, solubility in methyl ethyl ketone 15 1 mol (in terms of sulfonic acid functional group) is dissolved in advance, 1 mol of aniline is added, 15 liters of 1N hydrochloric acid (corresponding to 15 mol) is added, and this solution is stirred while maintaining at -5 to 0 ° C. The emulsion was emulsified and a sulfonic acid structure derived from dinonylnaphthalenesulfonic acid was introduced into the aniline. Here, the mixing ratio of the acid (hydrochloric acid) is 15.0 mol with respect to 1 mol of the aniline. Next, 1.2 mol of an oxidizing agent (ammonium persulfate) was added, and a polymerization reaction was performed for 20 hours. As the polymerization reaction proceeded, a green solution peculiar to polyaniline was obtained. Then, methanol was added to this solution, and the resulting precipitate was dried to obtain a conductive polymer.

Next, when 95 g of toluene was added to 5 g of the conductive polymer and stirred, a conductive polymer solution completely dissolved in toluene was obtained. When this conductive polymer solution was allowed to stand for 7 days, the state of the solution did not change while still being uniformly compatible. This solution was applied on a SUS plate and dried to prepare a coating film having a thickness of 20 μm, and then the electrical resistance of the coating film when a voltage of 10 V was applied in an environment of 25 ° C. × 50% RH, As a result of measurement according to JIS K 7194, the electric resistance was 8 × 10 ¹ Ω · cm. In addition, the conductive polymer coating film was allowed to stand for 10 days in a humid heat environment (80 ° C. × 95%), and the electrical resistance in an environment of 25 ° C. × 50% RH was measured in the same manner as described above. The resistance was 9.0 × 10 ¹ Ω · cm.

[Example 2]
(Preparation of conductive polymer)
In 4500 ml of ethyl acetate (SP value: 9.1), alkylbenzenesulfonic acid sodium salt represented by the formula (1) (having three alkyl substituents, the total number of carbon atoms of the alkyl substituents being 20) (Mn : 460, sulfonic acid group amount: 2.2 mmol / g, solubility in ethyl acetate of 15% or more) 1 mol (in terms of sulfonic acid functional group) was dissolved, 1 mol of o-anisidine was added, and then 15 liters of 1N hydrochloric acid (Equivalent to 15 mol) was added, and this solution was stirred and emulsified while maintaining at 2 to 8 ° C., and a sulfonic acid structure derived from the sodium alkylbenzene sulfonate was introduced into the o-anisidine. Here, the mixing ratio of the acid (hydrochloric acid) is 15.0 mol with respect to 1 mol of the o-anisidine. Next, 1.2 mol of an oxidizing agent (ammonium persulfate) was added, and a polymerization reaction was performed for 20 hours. As the polymerization reaction proceeded, a green solution specific to poly-o-anisidine was obtained. Then, methanol was added to this solution, and the resulting precipitate was dried to obtain a conductive polymer.

Next, when 95 g of MEK was added to 5 g of the conductive polymer and stirred, a conductive polymer solution completely dissolved in MEK was obtained. When this conductive polymer solution was allowed to stand for 7 days, the state of the solution did not change while still being uniformly compatible. This solution was applied on a SUS plate and dried to prepare a coating film having a thickness of 20 μm, and then the electrical resistance of the coating film when a voltage of 10 V was applied in an environment of 25 ° C. × 50% RH, As a result of measurement according to JIS K 7194, the electric resistance was 3 × 10 ² Ω · cm. In addition, the conductive polymer coating film was allowed to stand for 10 days in a humid heat environment (80 ° C. × 95%), and the electrical resistance in an environment of 25 ° C. × 50% RH was measured in the same manner as described above. The resistance was 2.2 × 10 ² Ω · cm.

Example 3
(Preparation of conductive polymer)
MIBK (SP value: 8.4) in 4500 ml, pentadecylbenzenesulfonic acid sodium salt (having one alkyl substituent, the total number of carbons of the alkyl substituent is 15) (Mn: 368, amount of sulfonic acid group: 2.7 mmol / g, 12% solubility in MIBK) 1 mol (converted to sulfonic acid functional group) was dissolved in advance, 1 mol of m-toluidine was added, and then 15 liters of 1N hydrochloric acid (equivalent to 15 mol) was added. The solution was stirred and emulsified while maintaining at 2 to 8 ° C., and the sulfonic acid structure derived from the sodium alkylbenzene sulfonate was introduced into the m-toluidine. Here, the mixing ratio of the acid (hydrochloric acid) is 15.0 mol with respect to 1 mol of the m-toluidine. Next, 1.2 mol of an oxidizing agent (ammonium persulfate) was added, and a polymerization reaction was performed for 20 hours. As the polymerization reaction proceeded, a green solution specific to poly m-toluidine was obtained. Then, methanol was added to this solution, and the resulting precipitate was dried to obtain a conductive polymer.

Next, 97 g of toluene was added to 3 g of the above conductive polymer and stirred to obtain a conductive polymer solution dissolved in toluene with a solubility of 25%. When this dissolved conductive polymer solution was allowed to stand for 7 days, the solution state remained unchanged and remained unchanged. This solution was applied on a SUS plate and dried to prepare a coating film having a thickness of 20 μm, and then the electrical resistance of the coating film when a voltage of 10 V was applied in an environment of 25 ° C. × 50% RH, As a result of measurement according to JIS K 7194, the electric resistance was 3 × 10 ² Ω · cm. In addition, the conductive polymer coating film was allowed to stand for 10 days in a humid heat environment (80 ° C. × 95%), and the electrical resistance in an environment of 25 ° C. × 50% RH was measured in the same manner as described above. The resistance was 2.2 × 10 ² Ω · cm.

Example 4
The amount of 1N hydrochloric acid in Example 2 was changed from 15.0 liters to 1.5 liters, and 2-ethylaniline was used instead of o-anisidine, and the electrical resistance was 3 × 10 ⁴ Ω · cm, which was left in a wet and heat environment. Thus, it was 3.5 × 10 ⁴ Ω · cm.

[Comparative Example 1]
After adding 0.2 mol of surfactant sodium dodecyl sulfate (SDS) to a mixed solution of 0.2 mol of aniline hydrochloride and 100 ml of water, the temperature was adjusted to 0 ° C. Next, 0.25 mol of ammonium persulfate was added while stirring the solution while maintaining the solution at 0 ° C. or lower, and a polymerization reaction was performed for 4 hours. Although the solution was initially heterogeneous, it became homogeneous as the polymerization reaction proceeded, and a green solution peculiar to polyaniline was obtained. Next, methanol was added to this solution to obtain a polyaniline precipitate, and then the electrical resistance was measured according to JIS K 7194. As a result, the electrical resistance was 115 Ω · cm.

  Next, MEK was added to the polyaniline precipitate and stirred, and the supernatant was separated. As a result, the compatibility between polyaniline and MEK was poor and a uniform solution was not obtained. The supernatant is applied on a glass plate and dried to produce a 1 μm thick coating, and then the electrical resistance of the coating when a voltage of 10 V is applied in an environment of 25 ° C. × 50% RH. As a result of measurement according to JIS K 7194, the electric resistance was 7800 Ω · cm.

  In addition, when toluene was added to the polyaniline precipitate and stirred, and the supernatant was separated, the compatibility between polyaniline and toluene was poor and a uniform solution was not obtained. The supernatant liquid was applied on a glass plate and dried to prepare a coating film having a thickness of 20 μm, and then the electrical resistance of the coating film when a voltage of 10 V was applied in an environment of 25 ° C. × 50% RH. As a result of measurement according to JIS K 7194, the electric resistance was 10500 Ω · cm.

[Comparative Example 2]
A polyaniline solution was prepared according to Example 1 of JP-A-2003-277500. That is, in a mixed solution of 0.2 mol of aniline hydrochloride and 100 ml of water, a surfactant polyoxyalkylene alkylphenyl ether sulfonate ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd., Hightenol No. 8). After adding 2 mol, it was adjusted to 5 ° C. Next, 0.2 mol of ammonium persulfate was added while stirring the solution while keeping the solution at 2 to 8 ° C., and a polymerization reaction was performed for 8 hours. Although the solution was initially heterogeneous, it became homogeneous as the polymerization reaction proceeded, and a green solution peculiar to polyaniline was obtained. Next, methanol was added to the solution to obtain a polyaniline precipitate, and then the electrical resistance was measured according to JIS K 7194. As a result, the electrical resistance was 35 Ω · cm.

  Next, MEK was added to the polyaniline precipitate and stirred to separate the supernatant. As a result, polyaniline and MEK were compatible with each other in the supernatant to form a uniform solution. The supernatant liquid was applied on a glass plate and dried to prepare a coating film having a thickness of 20 μm, and then the electrical resistance of the coating film when a voltage of 10 V was applied in an environment of 25 ° C. × 50% RH. As a result of measurement according to JIS K 7194, the electric resistance was 49 Ω · cm. In addition, the state of the supernatant after 7 days was that polyaniline aggregates (precipitates) were generated, and a coating film was again prepared in the same manner as described above, and the electrical resistance was measured to be 2880 Ω · cm. .

  In addition, toluene was added to the polyaniline precipitate and stirred, and the supernatant was separated. As a result, polyaniline and toluene were compatible with each other in the supernatant to form a uniform solution. The supernatant liquid was applied on a glass plate and dried to prepare a coating film having a thickness of 20 μm, and then the electrical resistance of the coating film when a voltage of 10 V was applied in an environment of 25 ° C. × 50% RH. As a result of measurement according to JIS K 7194, the electric resistance was 120 Ω · cm. In addition, the state of the supernatant after 7 days was an aggregate (precipitate) of polyaniline, and a coating film was again prepared in the same manner as described above, and the electrical resistance was measured to be 4380 Ω · cm. .

  From the above results, the products of all the examples were excellent in compatibility with MEK and toluene, and were excellent in stability over time (dissolution stability) and conductivity. Moreover, it was excellent in stability in a humid heat environment.

  On the other hand, the product of Comparative Example 1 was slightly inferior in compatibility with MEK and toluene. The product of Comparative Example 2 was initially good in solubility in MEK and toluene, but was slightly inferior in storage stability.

  The method for producing a conductive polymer solution of the present invention is useful for making the surface of a polymer material conductive or making various insulating materials conductive in various fields such as electricity, electronics, and materials.

Claims (5)

The following (A) component is dissolved in a solvent whose main component is a solvent having a solubility parameter of 8.0 to 10.0, and then the (B) component and the (C) component are added. After emulsifying and introducing the sulfonic acid structure derived from the component (A) into the monomer of the component (B), the monomer of the component (B) introduced with the sulfonic acid structure is polymerized. A process for producing a conductive polymer solution.
(A) A compound soluble in the above-mentioned solvent, in which at least one sulfonic acid functional group of a sulfonic acid group and a sulfonic acid group is bonded to a benzene ring or a naphthalene ring.
(B) A monomer comprising aniline and at least one of an aniline derivative having an alkyl group or an oxyalkyl group.
(C) 0.3-3.0N acid.   The method for producing a conductive polymer solution according to claim 1, wherein the component (A) has at least one alkyl substituent, and the total number of carbon atoms thereof is 15 to 25.   The mixing ratio of the acid of the component (C) is in the range of 1.0 to 30.0 mol with respect to 1 mol of the monomer of the component (B). The conductive polymer solution according to claim 1 or 2, Manufacturing method.   The method for producing a conductive polymer solution according to any one of claims 1 to 3, wherein the solubility of the component (A) in the solvent is 15% or more.   The solvent having a solubility parameter of 8.0 to 10.0 is at least one of an aromatic solvent and a ketone solvent, and the conductive polymer solution according to any one of claims 1 to 4. Manufacturing method.