JPH0468032A - Preparation of highly conductive organic polymer film - Google Patents

Abstract

PURPOSE:To easily prepare the title film useful for a battery, an electrode material, etc., by spreading the starting materials prepd. in a specified manner on a substrate and allowing the materials to undergo a chemically oxidative polymn. under specified conditions. CONSTITUTION:An oxidizing agent (e.g. FeCl3) and a binder polymer (e.g. PVAc) are dissolved in the same solvent (e.g. methanol) or indifferent solvents to give a solution (A). Separately, a monomer (e.g. pyrrole) or a soln. thereof in a solvent (e.g. methanol) are prepd. (B). A mixture obtd. by mixing components A and B is spread on a substrate and allowed to undergo a chemically oxidative polymn. under a controlled oxidation potential to give the title film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a highly conductive organic polymer film.

[Conventional technology and its issues]

Electrolytic oxidation polymerization methods and chemical oxidation polymerization methods are known as methods for producing highly conductive organic polymers.

In the electrolytic oxidation polymerization method, a supporting electrolyte and a polymer to be polymerized are dissolved in a suitable solvent, and a constant voltage is applied between inserted electrodes to form a conductive organic polymer on the anode plate. . Depending on the type of monomer used, the polymer obtained in this way can have a high conductivity of several tens to several thousand 3/cm by selecting optimal conditions such as solvent, electrolyte, applied voltage, and current value. Is possible. Moreover, since polymerization occurs on the electrode plate, it has the advantage that it can be obtained in the form of a polymer or film.

However, the electrolytic oxidation polymerization method has the drawbacks of high production costs, poor mass productivity, and distortions in the lines of electric force coming out of the electrodes, making it difficult to uniformly produce a large-area film. Furthermore, when considering forming a conductive thin film on a base material, the fact that the base material must already be a conductive material significantly limits the scope of use of this technique.

On the other hand, the chemical oxidative polymerization method uses an oxidizing agent to oxidize and polymerize the polymer, and its production method can be broadly divided into two types.

This is a method in which, for example, a monomer is dissolved in a suitable solvent and polymerized using a suitable oxidizing agent. Compared to the electrolytic oxidation polymerization method, this method yields polymers at a lower cost and is more suitable for mass production, but it generally has low conductivity, the polymer is obtained in powder form, and the polymer is generally insoluble and infusible. Therefore, it has the disadvantage of significantly inferior moldability.

Another method is to polymerize monomers deposited on a substrate with an oxidizing agent to form a conductive thin film. However, in this case as well, the conventional techniques had problems such as the electrical conductivity of the produced polymer was not high and the produced film was easily peeled off from the base material.

The present inventors have been conducting research to improve the chemical oxidation polymerization method in order to solve these problems, and have improved conductivity by selecting the solvent and oxidizing agent concentration in order to control the oxidation potential during the oxidation polymerization reaction. Possible improvement (Patent application 1986-5)
No. 5659), by incorporating a small amount of solvent during polymer molding, it is possible to obtain molded products with improved moldability and conductivity (Japanese Patent Application No. 85706/1983), and by CVD oxidative polymerization. It was discovered that a highly conductive film can be obtained by selecting an appropriate combination of solvent and oxidizing agent when producing a composite film (Japanese Patent Application No. 63-175).
No. 969).

However, when trying to form a conductive film on a substrate, even with the method of Japanese Patent Application No. 175969/1984, there is a limit to the thickness of the conductive polymer produced due to the 100% confectioning method, and it cannot be used as a film. There is also a limit to the conductivity, and furthermore, the solvent resistance of the formed thin film is not necessarily sufficient.

[Means to solve the problem]

The present inventors have made extensive efforts to obtain organic polymer films with high electrical conductivity by chemical oxidative polymerization using aromatic compounds and aromatic compounds containing heteroatoms such as nitrogen, oxygen, and sulfur. As a result of research, it was discovered that by adopting a special manufacturing method, an organic polymer film with high conductivity and improved adhesion to the substrate and solvent resistance could be obtained, and the present invention was developed. reached.

That is, in creating a highly conductive organic polymer film spread on a base material, the present invention prepares a solution (a) in which an oxidizing agent and a binder polymer are dissolved in the same solvent or in separate solvents. and separately prepare a solution (b) of monomer alone or a monomer dissolved in a solvent, and (a
) and (b) are mixed before being applied to the substrate, spread on the substrate, and then the conductive organic polymer is polymerized on the substrate by a chemical oxidation method while controlling the oxidation potential. The present invention provides a method for producing a highly conductive organic polymer film.

The present invention prepares a solution containing an oxidizing agent and a binder polymer, and simultaneously prepares a solution containing a conductive polymer monomer. 8 liquids are separately prepared, and after mixing both, they are spread on a substrate, and the oxidation potential is then increased to generate a conductive polymer and cause a crosslinking reaction of the binder polymer. It is. At this time, particularly excellent highly conductive organic polymers can be obtained by controlling the optimum oxidation potential by controlling the oxidizing agent concentration, the mixing ratio of the oxidizing agent and the reductant, the selection of the solvent, etc.

The compound used in the present invention is selected from those that undergo oxidative polymerization to produce a conjugated compound. Examples of such compounds include pyrrole derivatives, furan derivatives and thiophene derivatives among five-membered heterocyclic compounds. Compounds suitable as pyrrole derivatives include unsubstituted pyrrole, N-i substituted pyrrole, such as N-alkylpyrrole.

3-alkylpyrrole, 3,4-dialkylpyrrole, having an alkyl group, alkoxy group, or halogen atom of 01 to C6 at the 3-position or the 3- or 4-position;
3-alcoquinpyrrole, 3,4-dialkoxypyrrole, 3-chloropyrrole, 34-dichloropyrrole, etc. are available. Furan derivatives and thiophene derivatives include unsubstituted furan and unsubstituted thiophene and 3
3-alkylfuran, 3,4-dialkylfuran, 3-alcoquinfuran, 3,4-dialkoxyfuran, 3-chloro having a C1-C6 alkyl group, alkoxy group or halogen atom in the position or 3,4 position Fran, 3
．． 4-dichlorofuran, 3-alkylthiophene, 3.
Examples include 4-dialkylthiophene, 3-alkoxythiophene, 3,4-dialkoxythiophene, 3-chlorothiophene, and 3,4-dichlorothiophene. Examples of the 6-membered aromatic compound include aniline and hensosine.

In some cases, it may be difficult to find a soluble solvent for the above monomer that is compatible with the solvent of the oxidizing agent. In such a case, the monomer is converted into a soluble form in advance, or the solubility of the monomer can be changed by using an additive. For example, when water is used as a solvent, it is appropriate to add a Brønsted acid.

Suitable water-soluble salts include mineral acid salts such as hydrochloride, sulfate, and nitrate, but are not necessarily limited to these. Examples of the Bronsted acid include, but are not limited to, hydrochloric acid, sulfuric acid, nitric acid, hydrobromic acid, perchloric acid, and the like.

As the oxidizing agent used in the present invention, an oxidizing agent having an oxidation potential comparable to that of the electrolytic oxidative polymerization method for producing a highly conductive polymer in a reaction medium is suitable. For example, as an oxidizing agent for pyrrole, furan, and thiophene, iron (Jll
) salt, moly7den (V ) salt and ruthenium (III
) salt, etc. Examples of aniline oxidizing agents include chromic acid (■) salts, dichromic acid (ν1) salts, and permancanic acid (VII) salts.

The base material in the present invention is not particularly limited and may be any material that can be used as a support, including various inorganic and organic polymer materials.

Examples of inorganic materials include glass, quartz, and ceraminox.

On the other hand, the organic polymer material may be either thermosetting or thermoplastic, and is not particularly limited.

For example, nylon 6, nylon 66, nylon 12
polyamide, polyimide, polyethylene terephthalate (PET), polybutylene terephthalate (PET), etc.
BT), polyesters including polyesters exhibiting optical anisotropy, polyethers such as polycarbonate, polyether ether ketone, polyether ketone, polyoxymethylene, polyethylene oxide, polypropylene oxide, polyphenylene oxide, or polyphenylene sulfide. Contains 6p yellow po')? - Polyolefins such as polyethylene and polypropylene, polystyrene, rubber,
Polyvinyl chloride, ABS, fluororesin, phenolic resin,
Urea resin, melamine resin, etc. can be used. These polymers can be used in combination of two or more, or in the form of a copolymer.

Furthermore, various additives and reinforcing agents can be added to these polymers as necessary to improve mechanical, electrical, chemical properties, and flame retardant properties.

These substrates can be flexible or non-flexible thin plates (substrates) such as glass plates, PET films, non-plate-like moldings such as glass fibers, or granules,
The parable can be used as a glass piece.

As a specific example of the present invention, a case where a polypyrrole film is created on a glass plate will be described in detail.

Among the above oxidizing agents, FeC1, Fe(C10
4): Fe(III) salts such as +, RuCl3, RLI (
Ru(In) salts such as CIO, )3 or MoCl5
, MO(C104)S, etc.

(V) Salts and the like can be mentioned. Among these, from an economical point of view, it is preferable to use Fe(III) salts, particularly FeClx.

In the present invention, a solution in which the oxidizing agent and the binder polymer are dissolved in the same solvent or in separate solvents (
a) and separate monomers or monomers in each section? Two solutions are prepared: (b) and (b).

Here, as for each section, there are no particular limitations, unless either the oxidizing agent, binder polymer, or monomer is isolated and precipitated when the liquids (a) and (b) are mixed. The above solvents can also be used in combination. like this? Give examples for each section: water, methanol, ethanol, propatool, isopropanol, aliphatic alcohols such as butanol, pentanol, hexanol, octatool, halogenated alcohols such as hexafluoroisopropanol, phenol, chloro Examples include phenols such as phenol, Fresol, and fluorophenol, protic polar solvents, and aprotic polar solvents such as dimethylacetamide.

Further candidates include hydrocarbons such as henzene, toluene, xylene, hexane, and cyclohexane, halogenated compounds such as chloroform, and nonpolar solvents such as various ethers. Among these, methanol is particularly preferred for pyrrole because it is easy to set the optimum oxidation potential and because it is a common solvent with the binder polymer and the oxidizing agent.

As the binder polymer, it is possible to use a polymer that has affinity for both the monomer of the conductive polymer and the oxidizing agent, and has good wetting properties for the substrate. When FeC1+ is used as the oxidizing agent and a glass plate is used as the substrate, polyvinyl alcohol or polypropylene glycol can be used as the polyalcohol, polyvinyl acetate can be used as the polyester, and nylon 6, nylon 610, etc. can be used as the low molecular weight polyamide.

These binder polymers can be used alone or in combination. In the present invention, since these binder polymers ultimately become insoluble crosslinked products, low molecular weight ones such as oricomers, those soluble in solvents such as water, or hygroscopic ones can also be used. Among these, particularly good results are obtained when polyvinyl acetate and polyamide are used.

According to studies by the present inventors, the conductivity of the produced conductive polymer largely depends on the oxidation potential during oxidative polymerization. That is,
The oxidation potential during the polymerization reaction can be controlled by selecting the type of solvent, the oxidant/reduced form ratio of the oxidizing agent, and the temperature. When methanol is used as a solvent, the amount of the oxidizing agent, such as the reduced form of FeCl3, FeCl□, is 50 mo1% or less, preferably 0.01 to 10 mo1, based on the oxidant.
%, and the oxidation potential at which the conductivity of the resulting polymer is maximized is obtained.

Weight mixing ratio of FeC1 and polyvinyl acetate is 0.05
The amounts of both molds are adjusted to be 10:1, preferably 0.1 to 2:1, and dissolved in methanol. At this time, the amount dissolved in methanol does not have a significant effect on the subsequent properties.

Furthermore, in this solution, 50mo 1% of FeCl3 was added.
Hereinafter, the reduced FeCl2 is preferably added in an amount of 0.01 to 10 mo1%. Meanwhile, separately, pyrrole is dissolved in methanol. At this time, the molar concentration of pyrrole is adjusted so that when both solutions are mixed, it becomes 1,710 to 1 times, preferably 1/2 times, the concentration of the oxidizing agent. Here, the concentration of the oxidizing agent and the like in the solvent needs to be adjusted so as to obtain the optimum oxidation potential, which is a key point in obtaining a highly conductive film. The optimal oxidation potential here is 400 to 600 mV (VS 5CE) for pyrrole, preferably 450 to 550 n+V (VS 5CE) T
: Yes, the concentration of FeC13 which is an oxidant, and the oxidant /
It is good to adjust the reductant (FeC13/FeC1z) ratio. When the oxidant concentration is high, the polymerization reaction proceeds rapidly and rapidly in the solution before coating on the substrate, producing particulate matter, and the resulting film is non-uniform and has poor conductivity. extremely inferior.

Therefore, it is important to prepare a solution with a low concentration so that no polymer is formed in the solution. Further, when the oxidation potential is high, the same result occurs, which is not preferable, and it is possible to lower the oxidation potential by increasing the amount of FeC1□, which is a reductant, added. 2 above before applying the conductive polymer onto the substrate on which it is to be formed. Let's spend the night and stir well. Thereafter, the mixed solution is applied onto a substrate, for example, a glass plate.

The timing of coating is preferably a little longer than immediately after mixing, after the monomer polymerization has started to some extent; for example, higher conductivity can be obtained between 30 minutes and 5 hours. On the other hand, if more time passes, the reaction progresses too much and the conductivity decreases. As the application method, a brush, applicator, spin coating or spray method can be used. The solvent is removed by passing air or nitrogen through the substrate coated with the solution in a desiccator while maintaining the temperature at -10 to 40°C, preferably 0 to 40°C. As the solvent is removed and the oxidant concentration increases, the oxidation reaction becomes more active.

The oxidation reaction causes pyrrole to polymerize, while polyvinyl acetate undergoes a crosslinking reaction. As a result, a composite is formed in which a network of conductive polypyrrole is dispersed in crosslinked polyvinyl acetate that is insoluble in the solvent.

Furthermore, according to the present invention, the IW ratio of polypyrrole can be further increased by chemically or electrochemically reducing the polypyrrole, followed by oxidation by chemical oxidation or electrolytic oxidation and doping. Examples of the reducing agent used in the chemical reduction include hydranones such as hydrazine, hydrazine hydrate, and phenylhydrazine, and metal hydrides such as lithium aluminum hydride and sodium borohydride. The chemical reducing agent is usually used in an amount of 1 to 10 moles per nitrogen atom of the polymer, but is not necessarily limited thereto. In electrolytic reduction, ■ the produced polypyrrole is transferred onto a conductive substrate, ■ the polypyrrole film itself is used as an electrode,
Alternatively, (1) polypyrrole is generated on a conductive substrate, and the polypyrrole is detoped by electrolysis at an applied voltage of 0.01 to several tens of V, usually several (2), using the polypyrrole as a cathode.

After reduction, the neutral polypyrrole is again chemically reoxidized with an oxidizing agent and doped. As the dopant used for such redoping, any compound can be used as long as it has sufficient oxidizing power to reoxidize the reduced neutral polymer and has electron-accepting properties that are effective as a dopant. I can do it. Such oxidizing agents include iodine, bromine, halogens such as chlorine, arsenic pentafluoride,
Antimony pentafluoride, boron trifluoride, boron trichloride,
Ferric chloride, stannous chloride, titanium tetrachloride, zinc chloride,
Lewis acids such as cupric chloride, hydrochloric acid, sulfuric acid, and their salts (e.g., potassium hydrogen sulfate, sodium sulfate, sodium perchlorate, potassium perchlorate, iron perchlorate, etc.), or fluoroboric acid and its salts (for example), sodium boronate, potassium borofluoride, ammonium borofluoride, tetraalkylammonium borofluoride, etc.), but are not necessarily limited to these.

It is also possible to perform oxidation and doping electrochemically again. In this case, the above oxidizing agent may be used as a supporting electrolyte and polypyrrole may be used as an anode for electrolysis.

[Effects of the Invention] According to the present invention, a highly conductive organic polymer film can be easily produced by chemical oxidative polymerization, and the highly conductive organic polymer film thus produced can be used as a capacitor electrode. ,
It can be used for batteries, electrode materials, conductive films, conductive circuits for printed I-boards, lightweight electric wires, electromagnetic shielding materials, conductive fillers, antistatic materials, etc.

〔Example〕

The present invention will be described below with reference to Examples, but the present invention is in no way limited by these Examples.

Example 1 12 g of ferric chloride (Wako type), 12 g of ferric chloride (Wako type) and 1 l of polyvinyl acetate (Nippon Gosei type)
Four 100 g of methanol (Wako type) were dissolved.

When the oxidation potential of the solution was measured, it was found to be 500 mV (VS
5CE). On the other hand, pyrrole (Wako type) was purified by distillation under a nitrogen atmosphere, and 2 g thereof was dissolved in 10 g of methanol. Both were mixed and stirred, and after 2 hours, the mixed/8 liquid was applied onto a glass plate by a spin coach ink method.

The sample was placed in a desiccator as it was, and nitrogen gas was passed through it at room temperature to evaporate and remove methanol. As the solvent evaporated, the /8 liquid changed from yellow to dark green, indicating the formation of a film. After the solvent had been evaporated, the product was thoroughly dried, washed with methanol for 12 hours to remove soluble components, and further dried under vacuum at room temperature for 24 hours. The electrical conductivity of the produced polypyrrole film was measured by a four-terminal method. The test results are shown in Table I.

Example 2 Ferric chloride (Wako'I) 20 g, ferric chloride (Wako type) 5 ■ and polyvinyl acetate (Nippon Gosei Chemical type) 1
0g was dissolved in 100g of methanol (Wako type). When the oxidation potential of the solution was measured, it was 540 mV (VS 5
CE). On the other hand, pyrrole (Wako type) was purified by distillation under a nitrogen atmosphere, and 2 g thereof was dissolved in methanol Log. Both were mixed and stirred, and after 30 minutes, the mixed solution was applied onto a polyethylene terephthalate (PET) film using a spin coach ink method. The pond is Example 1
Two polypyrrole films were prepared and evaluated in the same manner as above. The test results are shown in Table 1.

Example 3 Ferric chloride (Wako type) 20g, ferric chloride (Wako type)
121TIgδ and polyvinyl alcohol (Nippon Gosei Chemical Co., Ltd.) ]Og- were dissolved in 100 g of a 3/1 mixed solution of methanol/distilled water. The oxidation potential was measured at night and found to be 520 mV (VS 5CE).

On the other hand, pyrrole (Wako type) was purified by distillation under a nitrogen atmosphere, and 2 g of it was added to a mixed solution of methanol/distilled water - 3/1.
Dissolved in 0g. Both were mixed and stirred, and after 30 minutes, the mixed solution was applied onto a glass plate by spin coating. Other procedures were the same as in Example 1 to prepare a polypyrrole film and evaluate it. The test results are shown in Table 1.

Comparative Example 1 Ferric chloride (Wako type) 20g, ferric chloride (Wamoto type) 20g and polyvinyl acetate (Nippon Gosei Kaji type) 10g
g was dissolved in 100 g of methanol (manufactured by Wako). When the oxidation potential of the solution was measured, it was found to be 380 mV (VS 5C
E). On the other hand, pyrrole (manufactured by Wako) was purified by distillation under a nitrogen atmosphere, and 2 g thereof was dissolved in methanol Log. Both were mixed and stirred, and after 30 minutes, the mixed solution was applied onto a glass plate by a spin coach ink method. The rest of the process was the same as in Example 1 to prepare a polypyrrole film and evaluate it. The test results are shown in Table 1.

Comparative Example 2 55 g of ferric chloride (manufactured by Wako) and 10 g of polyvinyl acetate (Nihon Gosei Kaji type) were mixed with methanol (manufactured by Wako) 100
Dissolved in g. When the oxidation potential of the solution was measured, it was 63
It was 0 mV (VS 5CE). On the other hand, pyrrole (
(manufactured by Wako) was purified by distillation under a nitrogen atmosphere, and 2 g of it was dissolved in 10 g of methanol. Both were mixed and stirred, and after 30 minutes, the mixed solution was applied onto a glass plate by spin coating.

The rest of the process was the same as in Example 1 to prepare a polypyrrole film and evaluate it. The test results are shown in Table 1.

Table 1 Example 4 The polypyrrole film with a conductivity of 10 S/cm prepared in Example 1 was immersed in an ether solution (10 ml) of phenylhydrazine (200 II + g), and 1 was added to the polypyrrole film with stirring at room temperature.
Allowed time to react. After the reaction, the film was thoroughly washed with ether and dried in vacuum. The film was oxidized by exposure to iodine vapor for 10 hours in a desiccator at room temperature. When the electrical conductivity of this redoped polypyrrole film was measured, it was found to be 20 S/cm, indicating an increase in electrical conductivity.

Claims (1)

[Claims] 1. In preparing a highly conductive organic polymer film spread on a substrate, a solution (a) in which an oxidizing agent and a binder polymer are dissolved in the same solvent or in different solvents is used. and separately prepare a monomer alone or a solution (b) of the monomer dissolved in a solvent, mix (a) and (b) before applying to the substrate, and then spread on the substrate, A method for producing a highly conductive organic polymer film, which comprises then polymerizing the conductive organic polymer on the substrate by a chemical oxidation method while controlling the oxidation potential. 2. The method for producing a highly conductive organic polymer film according to claim 1, wherein the chemical oxidation polymerization on the substrate is carried out while removing the solvent by evaporation. 3. The method for producing a highly conductive organic polymer film according to claim 1 or 2, wherein a solution in which the oxidizing agent and the binder polymer are dissolved in the same solvent is used as the solution (a). 4. The method for producing a highly conductive organic polymer film according to any one of claims 1 to 3, wherein the chemical oxidative polymerization is carried out by controlling the oxidation potential by adding a reduced form of the oxidizing agent to the oxidizing agent. 5. The method for producing a highly conductive organic polymer film according to any one of claims 1 to 4, wherein the monomer is a compound that becomes a molecule constituting a conjugated chain when oxidatively polymerized. 6. The method for producing a highly conductive organic polymer film according to any one of claims 1 to 5, wherein the monomer is selected from pyrrole-based, furan-based, and thiophene-based compounds. 7. The method for producing a highly conductive organic polymer film according to claim 6, wherein the oxidizing agent is an iron (III) salt, a molybdenum (V) salt, or a ruthenium (III) salt. 8. The method for producing a highly conductive organic polymer film according to any one of claims 1 to 5, wherein the monomer is selected from aniline-based and benzidine-based compounds. 9. The method for producing a highly conductive organic polymer film according to claim 8, wherein the oxidizing agent is a chromate (IV) salt, a dichromate (VI) salt, or a permanganate (VII) salt. 10 The solvent dissolves any one of the binder polymer, the oxidizing agent and the monomer, and the solution (a) according to claim 1 and the solution (
Claims 1 to 3, which are solvents that do not isolate and precipitate any of the binder polymer, oxidizing agent, and monomer when mixed with b).
9. The method for producing a highly conductive organic polymer film according to any one of 9. 11. The method for producing a highly conductive organic polymer membrane according to any one of claims 1 to 10, wherein the solvent is selected from water, alcohols, aromatic hydrocarbons, ethers, halogenated hydrocarbons, and ketones. 12. The highly conductive organic polymer according to any one of claims 1 to 11, wherein the highly conductive organic polymer film obtained by chemical oxidation polymerization is further reduced, and then oxidized with an oxidizing agent effective as an acceptor and doped. Method for manufacturing a coalescing membrane.