JP2008214401A - Method for producing nano-dispersed polypyrrole fine particle in organic solvent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing nano-dispersed polypyrrole fine particles in an organic solvent. <P>SOLUTION: This method for producing nano-dispersed polypyrrole fine particles in the organic solvent is provided by starting polymerization in an aqueous medium containing the pyrrole and/or a pyrrole derivative of an amount capable of being dissolved in the aqueous medium, an anionic surfactant and/or a nonionic surfactant and an oxidizing agent, further progressing the polymerization by adding the solvent at a time point that the polymerization rate of the polypyrrole becomes 10 to 60% and then recovering the organic solvent layer from the layer-separated two layers. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing polypyrrole fine particles nano-dispersed in an organic solvent layer through a polymerization reaction in an aqueous medium. Specifically, polymerization is initiated in an aqueous medium containing an amount of pyrrole and / or pyrrole derivative, anionic surfactant and / or nonionic surfactant, and an oxidizing agent that can be solubilized in the aqueous medium, and the polymerization rate of polypyrrole The present invention relates to a method in which an organic solvent is added to the polymerization system at a point of 10 to 60% and the polymerization is further advanced, and then the organic solvent layer of the two separated layers is recovered.

Several methods for producing conductive polymer fine particles nano-dispersed in an organic solvent have been reported.
Japanese Patent Application Laid-Open No. 2005-314538 discloses a method for producing conductive polymer fine particles comprising pyrrole and / or a pyrrole derivative nano-dispersed in an organic solvent. Here, the organic solvent, water, and anionic surface activity are disclosed. Of pyrrole and / or a pyrrole derivative monomer in an O / W emulsion obtained by mixing and stirring an agent, and a method of producing polypyrrole fine particles nano-dispersed in an organic solvent by oxidative polymerization of the monomer It is shown.

  Japanese Patent Application Laid-Open No. 2005-60671 describes a method for producing a polyaniline conductive ink. Here, there is a step of polymerizing aniline in an aqueous medium in the presence of an anionic surfactant to obtain a polyaniline colloid. Shows a method for producing polyaniline fine particles nano-dispersed in an organic solvent comprising the step of adding one or more organic solvents to the reaction solution after completion of the polymerization reaction and separating the two layers to transfer the polyaniline colloid to the organic layer. ing.

For the purpose of producing polypyrrole fine particles nano-dispersed in an organic solvent through a polymerization reaction in an aqueous medium, the production method described in JP-A-2005-60671 was carried out using pyrrole monomer instead of aniline. When polymerization of pyrrole in an aqueous medium is completed, it is already in the form of several hundred μm particles or several millimeters or more, and even if an organic solvent is added in this state, No dispersed polypyrrole fine particles were obtained.
Accordingly, it has been clarified that the polypyrrole fine particles nano-dispersed in an organic solvent through a polymerization reaction in an aqueous medium cannot be produced simply by using the production method described in JP-A-2005-60671.
JP 2005-314538 A JP 2005-60671 A

  An object of the present invention is to provide a method for producing polypyrrole fine particles nano-dispersed in an organic solvent layer through a polymerization reaction in an aqueous medium.

As a result of intensive studies to solve the above problems, the present inventors include an amount of pyrrole and / or a pyrrole derivative, an anionic surfactant and / or a nonionic surfactant, and an oxidizing agent that can be solubilized in an aqueous medium. When polymerization is started in an aqueous medium, and when the polymerization rate of polypyrrole reaches 10 to 60%, an organic solvent is added to the polymerization system and the polymerization proceeds further. As a result, the resulting polypyrrole fine particles have a large particle size. It was found that polypyrrole fine particles stably dispersed in the organic solvent layer can be obtained when the stirring is stopped and the two layers are separated, and further, the method includes only an anionic surfactant. Rather than
Even if a nonionic surfactant is used, polypyrrole fine particles nano-dispersed in an organic solvent layer can be obtained, and by adding a dopant in an aqueous medium in advance, it has excellent conductivity that could not be obtained by a conventional method and The inventors have also found that polypyrrole nano-dispersed fine particles with very little change in electrical conductivity (resistance value) over time can be obtained, thereby completing the present invention.

That is, the present invention
1. A method for producing polypyrrole fine particles nano-dispersed in an organic solvent layer,
Polymerization is initiated in an aqueous medium containing an amount of pyrrole and / or pyrrole derivative, anionic surfactant and / or nonionic surfactant, and an oxidizing agent that can be solubilized in the aqueous medium, and the polymerization rate of the polypyrrole is 10 to 10%. A method by adding an organic solvent to the polymerization system at the time when it reaches 60% and further proceeding the polymerization, and then recovering the organic solvent layer of the two separated layers,
2. The organic solvent is added when the particle size of the polypyrrole is 100 nm or less. A method for producing the polypyrrole fine particles described above,
3. The above-mentioned 1., wherein a dopant is present in the aqueous medium. A method for producing the polypyrrole fine particles described above,
It is about.

  The method for producing polypyrrole fine particles nano-dispersed in an organic solvent layer according to the present invention is obtained by adding an organic solvent at a time when the polymerization rate is 10 to 60% in polypyrrole polymerization in an aqueous medium. The problem when adopting the manufacturing method of No. 1, that is, the particle size of the produced polypyrrole becomes too large to disperse in the organic solvent layer, thereby stably nano-dispersing in the organic solvent layer. It is possible to provide a production method capable of easily obtaining polypyrrole fine particles.

Furthermore, the present invention not only enables a method for producing nano-dispersed polypyrrole fine particles using a nonionic surfactant, but also by adding a dopant in advance, it has excellent conductivity and conductivity that could not be obtained by conventional methods. It is also possible to obtain polypyrrole nano-dispersed fine particles with very little change over time in the rate (resistance value).
In particular, since the nonionic surfactant does not act as a dopant, the conductivity can be easily controlled by using the surfactant.
It is also possible to control the particle size of the resulting polypyrrole by controlling the polymerization rate in the aqueous medium at the time of adding the organic solvent.
In the oxidative polymerization of polypyrrole in an aqueous medium, why the addition of an organic solvent during the polymerization reaction does not increase the particle size of the polypyrrole and does not cause aggregation of the polypyrrole particles. Whether nanodispersed polypyrrole fine particles can be easily obtained is not necessarily clear.
However, it is observed that the presence of a certain amount of residual monomer (unreacted monomer) in the reaction system is important in order to prevent the polypyrrole particle size from becoming too large and to cause aggregation of the polypyrrole particles. Therefore, it is considered that when the polymerization rate is improved and the amount of the residual monomer is decreased, the particle size of the polypyrrole is suddenly increased and the polypyrrole particles are aggregated.

The method for producing the polypyrrole fine particles of the present invention is considered to be completely different from the method for producing the polypyrrole fine particles described in JP-A-2005-314538 in the production process and operation of the polypyrrole fine particles.
For example, FIG. 1 shows a schematic comparison of the operation according to the method for producing polypyrrole fine particles of the present invention and the operation according to the method for producing polypyrrole fine particles described in JP-A-2005-314538. Is different.
Moreover, the schematic diagram of the production | generation process of the polypyrrole particle assumed in the manufacturing method of the polypyrrole microparticles | fine-particles described in Unexamined-Japanese-Patent No. 2005-314538 was shown in FIG.
Here, it is considered that most of the pyrrole monomer 1 is taken into the fine oil droplets in the emulsion, and the surfactant 2 (anion) is present on the surface of the oil droplets. When the oxidizing agent 4 is added here, it is considered that polymerization of the pyrrole monomer occurs in the oil droplets and the polypyrrole fine particles 3 are generated. As a result, when stirring is stopped, it is considered that the polypyrrole fine particles 3 are separated into an organic phase and an aqueous phase in which the polypyrrole fine particles 3 are dispersed.
On the other hand, the schematic diagram of the production process of the polypyrrole fine particles assumed in the method for producing the polypyrrole fine particles of the present invention is considered to be completely different from the above as shown in FIG.
It is considered that pyrrole monomer 1 dissolved in water is present so as to be surrounded by hydrophobic sites of a plurality of surfactants 2 (anions and / or nonions), and when oxidant 4 is added thereto, It is considered that polymerization of the pyrrole monomer occurs in the region surrounded by the hydrophobic site. When an organic solvent is added, the polypyrrole fine particles 3 are dispersed in large oil droplets, and the polymerization reaction is considered to proceed. When the stirring is stopped, the polypyrrole fine particles 3 are separated into a dispersed organic phase and an aqueous phase. It is considered a thing.

The present invention will be described in more detail.
The method for producing polypyrrole fine particles nano-dispersed in an organic solvent layer of the present invention includes an amount of pyrrole and / or a pyrrole derivative, an anionic surfactant and / or a nonionic surfactant, and an oxidizing agent that can be solubilized in an aqueous medium. Polymerization is started in an aqueous medium, and when the polymerization rate of polypyrrole reaches 10 to 60%, an organic solvent is added to the polymerization system to further proceed the polymerization, and then the organic layer of the two layers separated is separated. This is achieved by collecting the solvent layer.

  Examples of pyrrole and / or pyrrole derivatives that can be used in the present invention include pyrrole, N-methylpyrrole, N-ethylpyrrole, N-phenylpyrrole, N-naphthylpyrrole, N-methyl-3-methylpyrrole, N-methyl- 3-ethylpyrrole, N-phenyl-3-methylpyrrole, N-phenyl-3-ethylpyrrole, 3-methylpyrrole, 3-ethylpyrrole, 3-n-butylpyrrole, 3-methoxypyrrole, 3-ethoxypyrrole, 3-n-propoxypyrrole, 3-n-butoxypyrrole, 3-phenylpyrrole, 3-toluylpyrrole, 3-naphthylpyrrole, 3-phenoxypyrrole, 3-methylphenoxypyrrole, 3-aminopyrrole, 3-dimethylaminopyrrole , 3-diethylaminopyrrole, 3-diphenylami Pyrrole, 3-methylphenylamino pyrrole, 3-phenyl naphthyl amino pyrrole, and the like. Particularly preferred is pyrrole.

The amount of pyrrole and / or pyrrole derivative that can be solubilized in an aqueous medium is 80 g / L or less, particularly preferably 20 g / L to 1 g / L, relative to water.
When an amount of pyrrole and / or a pyrrole derivative that cannot be solubilized in an aqueous medium is added (a pyrrole and / or pyrrole derivative having a saturation concentration or more), a massive polypyrrole is generated immediately after the start of polymerization, and the desired fine particles are obtained. I can't. On the other hand, when the monomer of pyrrole and / or pyrrole derivative is 1 g / L or less, the polymerization reaction is extremely slow, and it takes a long time to obtain desired fine particles.

As the anionic surfactant that can be used in the present invention, a commonly used anionic surfactant can be used, and is not particularly limited, but has a plurality of hydrophobic ends (for example, branched into hydrophobic groups). Those having a structure and those having a plurality of hydrophobic groups are preferred. By using such an anionic surfactant having a plurality of hydrophobic ends, stable micelles can be formed, and separation of the aqueous phase and the organic solvent phase after polymerization is easy.
Conductive fine particles dispersed in an organic solvent phase are easily available. Among anionic surfactants having multiple hydrophobic ends, di-2-ethylhexyl sulfosuccinate (4 hydrophobic ends), di-2-octyl sodium sulfosuccinate (4 hydrophobic ends) and branched alkylbenzene sulfone Acid salts (two hydrophobic ends) can be preferably used.
Moreover, said anionic surfactant can be used individually or in mixture of 2 or more types.

Nonionic surfactants that can be used in the present invention include, for example, polyoxyethylene alkyl ethers, alkyl glucosides, fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene fatty acid esters , Fatty acid alkanolamides, and polyoxyethylene alkylphenyl ethers.
Said nonionic surfactant can be used individually or in mixture of 2 or more types.

  The amount of the anionic surfactant and / or nonionic surfactant used is preferably less than 0.2 mol, more preferably 0.05 mol to 0.15 mol, relative to 1 mol of the monomer of pyrrole and / or a pyrrole derivative. If the amount is less than 0.05 mol, the yield and the dispersion stability are lowered. On the other hand, if the amount is 0.2 mol or more, the resulting conductive fine particles may have a conductivity humidity dependency.

  Examples of the oxidizing agent used in the present invention include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid and chlorosulfonic acid, organic acids such as alkylbenzenesulfonic acid and alkylnaphthalenesulfonic acid, potassium persulfate, ammonium persulfate and peroxidation. Peroxides such as hydrogen can be used. These may be used alone or in combination of two or more. Polypyrrole can be polymerized even with a Lewis acid such as ferric chloride, but the produced particles may aggregate and the polypyrrole may not be finely dispersed. Particularly preferred oxidizing agents are persulfates such as ammonium persulfate.

  The amount of the oxidizing agent to be used is preferably 0.1 mol or more and 0.8 mol or less, more preferably 0.2 to 0.6 mol, with respect to 1 mol of pyrrole and / or pyrrole derivative monomer. If the amount is less than 0.1 mol, the degree of polymerization of the monomer decreases, making it difficult to separate and collect the conductive fine particles. On the other hand, if the amount is 0.8 mol or more, the polypyrrole aggregates to increase the particle size of the conductive fine particles. Stability deteriorates.

The aqueous medium used in the present invention is basically water, and if desired, a dopant or the like can be added for the purpose of improving the conductivity of the polypyrrole fine particles to be formed and reducing the temporal change of the conductivity.
The amount of the aqueous medium to be used is an amount capable of solubilizing the pyrrole and / or pyrrole derivative to be used, that is, an amount such that the concentration of pyrrole and / or pyrrole derivative is 80 g / L or less as defined above. Particularly preferred is an amount of 20 g / L to 1 g / L.

As described above, a dopant can be added in the present invention.
In the polymerization in the O / W type emulsion described in JP-A-2005-60671, a dopant is not used. Therefore, the conductivity of the obtained polypyrrole is not necessarily high, and changes with time are not observed. It was easy to receive.
In the present invention, by adding a predetermined dopant to the aqueous medium, it may be possible to improve the conductivity and reduce the change with time.
The dopant used in the present invention is not particularly limited as long as it is soluble in the monomer of pyrrole and / or pyrrole derivative, and generally comprises a polymer of pyrrole and / or pyrrole derivative. An acceptor dopant suitably used for the conductive fine particles can be used as appropriate. Typical examples thereof include polystyrene sulfonic acid, paratoluene sulfonic acid, methane sulfonic acid, trifluoromethane sulfonic acid, anthraquinone sulfonic acid, and benzene sulfone. Examples thereof include sulfonic acids such as acid, naphthalenesulfonic acid, sulfosalicylic acid, dodecylbenzenesulfonic acid, and allylsulfonic acid, halogens such as perchloric acid, chlorine, and bromine, Lewis acid, and protonic acid. These may be in the acid form or in the salt form. Preferred from the viewpoint of solubility in monomers, tetrabutylammonium perchlorate, tetraethylammonium perchlorate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium trifluoromethanesulfonate, tetrabutylammonium trifluorosulfonimide, dodecylbenzene Examples thereof include sulfonic acid and p-toluenesulfonic acid.

  When the dopant is used, the dopant is preferably used in an amount of 0.01 to 0.3 molecule of dopant per pyrrole polymer unit unit to be generated. When the amount is 0.01 molecule or less, the amount of dopant necessary to form a sufficient conductive path is insufficient, and it is difficult to obtain high conductivity. On the other hand, addition of 0.3 molecule or more does not improve the doping rate, so the addition of 0.3 molecule or more dopant is not economically preferable. Here, the pyrrole polymer unit unit refers to a repeating portion corresponding to one molecule of a pyrrole polymer monomer obtained by polymerizing a pyrrole monomer.

In the production method of the present invention, after polymerization is initiated in an aqueous medium containing an amount of pyrrole and / or a pyrrole derivative, an anionic surfactant and / or a nonionic surfactant, and an oxidizing agent that can be solubilized in the aqueous medium, An organic solvent is added when the polymerization rate of polypyrrole reaches 10 to 60%. More preferably, the organic solvent is added when the polymerization rate of the polypyrrole reaches 20 to 50%. When the organic solvent is added when the polymerization rate is less than 10%, the conjugated double bond of polypyrrole is not sufficiently grown, so that predetermined conductivity cannot be obtained. Further, the subsequent polymerization becomes extremely slow, and the separation of water and the organic solvent becomes extremely poor. On the contrary, when the organic solvent is added when the polymerization rate exceeds 60%, the size of the polypyrrole particles transferred to the organic solvent becomes large particles of several hundred nm or more, and the dispersion stability is also poor.
The polymerization rate can be easily calculated from the ratio of the initially added monomer amount and the residual monomer amount by measuring the residual monomer using gas chromatography.

The presence of a certain amount of residual monomer (unreacted monomer) in the reaction system is considered important in order not to make the particle size of the polypyrrole too large and to cause aggregation of the polypyrrole particles. Therefore, it is considered that when the polymerization rate is improved and the amount of the residual monomer is decreased, the particle size of the polypyrrole is suddenly increased and the polypyrrole particles are aggregated.
That is, in order not to make the particle size of polypyrrole too large and to cause aggregation of polypyrrole particles, the amount of residual monomer (unreacted monomer) in the reaction system is 40 to 90 of the amount of monomer initially added. It can be said that it is important to add an organic solvent at the time when% remains.
Similarly, the size of the fine particles dispersed in the aqueous medium at the time of adding the organic solvent is also extremely important. FIG. 4 shows a graph showing the relationship between the polymerization rate (%) of polypyrrole in an aqueous medium and the average particle diameter (nm) of polypyrrole obtained at that time. From this graph, the polymerization rate of polypyrrole exceeds a certain value. It can be seen that the average particle size of polypyrrole increases rapidly. Therefore, for example, even when an organic solvent is added when the average particle size of polypyrrole exceeds 100 nm, the size of the polypyrrole particles transferred to the organic solvent tends to be large particles of several hundred nm or more as a result. Dispersion stability tends to be poor.
Therefore, it is preferable to add the organic solvent when the particle size of the polypyrrole is 100 nm or less.
In addition, the average particle diameter of polypyrrole can be easily measured by a laser Doppler method.

The organic solvent to be added is not particularly limited as long as it is an organic solvent having a solubility in water of 1% or less. For example, aliphatic esters such as butyl acetate, aromatic solvents such as toluene, ketones such as methyl ethyl ketone, Cyclic saturated hydrocarbons such as cyclohexane, chain saturated hydrocarbons such as n-octane, chain saturated alcohols such as n-octanol, aromatic esters such as methyl benzoate, and aliphatic ethers such as diethyl ether Is mentioned.
The amount of the organic solvent to be used is preferably 5 to 40% (v / v), particularly preferably 10 to 25% (v / v) by volume with respect to the amount of water used in the polymerization reaction.
If it is less than 5% (v / v), the particle density becomes high and the dispersibility becomes poor, resulting in aggregation. When it exceeds 40% (v / v), the particle density becomes relatively low, so the repulsive force between the particles becomes small and dispersion cannot be maintained.

The method for producing the polypyrrole fine particles is performed, for example, in the following steps:
(A) a step of adding an anionic surfactant and / or a nonionic surfactant, a monomer of pyrrole and / or a pyrrole derivative and optionally a dopant to water and mixing and stirring;
(B) adding an oxidizing agent to start oxidative polymerization;
(C) adding an organic solvent when the polymerization rate becomes 10 to 60%,
(D) a step of mixing and stirring to further advance the polymerization reaction;
(E) A step of separating the organic phase and collecting polypyrrole fine particles nano-dispersed in the organic solvent layer.

  Each of the above steps can be performed using means known to those skilled in the art. For example, the mixing and stirring is not particularly limited. For example, a magnetic stirrer, a stirrer, a homogenizer, and the like can be selected as appropriate. The polymerization temperature is 0 to 25 ° C, preferably 20 ° C or less. If the polymerization temperature exceeds 25 ° C., side reactions occur, which is not preferable.

Thus, the polypyrrole fine particles nano-dispersed in the organic solvent layer obtained by the production method of the present invention can be preferably used as the conductive component of the conductive paint. The conductive paint comprises polypyrrole fine particles dispersed in an organic solvent, and a resin such as a dispersion stabilizer, a thickener, and an ink binder can be added as required for the purpose of use and application.
These polypyrrole fine particles can be dried to form powdery polypyrrole fine particles, and the powdered polypyrrole fine particles can also be used as a conductive filler or the like in a synthetic resin molded product or the like.

  Moreover, a conductive thin film can also be obtained by applying the above-mentioned conductive paint to a substrate and drying it. The object to be applied is not particularly limited, but it is necessary to select it so as not to be damaged by the organic solvent contained in the conductive paint. Also, the coating method is not particularly limited, and printing or coating can be performed using, for example, a gravure printing machine, an inkjet printing machine, dipping, a spin coater, a roll coater, or the like.

  Further, the polypyrrole fine particles of the present invention are preferably applied to various applications such as rust preventive paints, semiconductor materials, electrolytes for capacitors, hole transport materials for organic EL elements, and electrode materials for secondary batteries, in addition to conductive paints. be able to.

  The following examples illustrate the invention in more detail. However, the examples are for illustrating the present invention and are not intended to limit the present invention in any way.

Example 1
Dissolve 1.5 mmol of sodium di-2-ethylhexyl sulfosuccinate (anionic surfactant: Perex OT-P) in 100 mL of ion-exchanged water, then add 21.2 mmol of pyrrole monomer and stir for 30 minutes, then 0.12M ammonium persulfate 50 mL of aqueous solution (corresponding to 6 mmol) was added and the reaction was carried out for 1 hour (polymerization rate 50%, average particle diameter 78 nm). Then 25 mL of butyl acetate was added and stirred for 4 hours. After completion of the stirring, the organic phase was recovered, washed several times with ion-exchanged water, and black conductive fine particles (average particle size 85 nm) were obtained in a state dispersed in butyl acetate.

Examples 2 to 8
Conductive fine particles were obtained in the same manner as in Example 1 except that butyl acetate (organic solvent) was changed to the organic solvent shown in the following table (Table 1).

Example 9
After adding the pyrrole monomer, the same operation as in Example 1 was performed except that 2 mmol of sodium dodecylbenzenesulfonate was newly added to obtain conductive fine particles.

Example 10
The same operation as in Example 9 was conducted except that di-2-ethylhexyl sulfosuccinate sodium (anionic surfactant: Perex OT-P) was changed to polyoxyethylene alkyl ether nonionic surfactant Emulgen 409P (Kao Corporation). Conductive fine particles were obtained.

Example 11
The same operation as in Example 1 except that 1.5 mmol of di-2-ethylhexyl sodium sulfosuccinate (anionic surfactant: Perex OT-P) was changed to 0.42 mmol and nonionic surfactant Emulgen 409P2.1 mmol was added. The conductive fine particles were obtained.

Example 12
After adding the pyrrole monomer, the same operation as in Example 11 was performed except that 2 mmol of sodium dodecylbenzenesulfonate was newly added to obtain conductive fine particles.

Example 13
Conductive fine particles were obtained in the same manner as in Example 1 except that the reaction time of 1 hour after adding the ammonium persulfate aqueous solution was changed to 15 minutes (polymerization rate 10%, average particle diameter 15 nm).

Example 14
Conductive fine particles were obtained in the same manner as in Example 1 except that the reaction time for 1 hour after adding the aqueous ammonium persulfate solution was changed to 75 minutes (polymerization rate 60%, average particle size 100 nm).

Comparative Example 1
Conductive particles were obtained in the same manner as in Example 1 except that the reaction time for 1 hour after adding the ammonium persulfate aqueous solution was changed to 90 minutes (polymerization rate 70%, average particle diameter 300 nm).

Comparative Example 2
Conductive fine particles were obtained in the same manner as in Example 1 except that the reaction time for 1 hour after adding the aqueous ammonium persulfate solution was changed to 5 minutes (polymerization rate 5%, average particle diameter 2 nm).

Comparative Example 3 (Production method according to polymerization method in O / W type emulsion described in JP-A-2005-314538)
1.5 mmol of di-2-ethylhexyl sodium sulfosuccinate was dissolved in 50 mL of butyl acetate, and 100 mL of ion-exchanged water was further added, followed by stirring until emulsification was maintained at 20 ° C. To the obtained emulsion, 21.2 mmol of pyrrole monomer was added and stirred for 30 minutes, and then 50 mL (corresponding to 6 mmol) of a 0.12M ammonium persulfate aqueous solution was added dropwise little by little and reacted for 4 hours. The reaction was allowed to stand after completion of the reaction, but separation of the organic phase and the aqueous phase was not clear, and the organic phase could not be recovered.

Comparative Example 4 (Production method according to polymerization method in O / W type emulsion described in JP-A-2005-314538)
1.5 mmol of polyoxyethylene alkyl ether nonionic surfactant Emulgen 409P (Kao Corporation) was dissolved in 50 mL of toluene, and further 100 mL of ion-exchanged water was added and stirred until emulsification was maintained at 20 ° C. To the obtained emulsion, 21.2 mmol of pyrrole monomer was added and stirred for 30 minutes, and then 50 mL (corresponding to 6 mmol) of a 0.12M ammonium persulfate aqueous solution was added dropwise little by little and reacted for 4 hours. The reaction was allowed to stand after completion of the reaction, but separation of the organic phase and the aqueous phase was not clear, and the organic phase could not be recovered.

Comparative Example 5 (Production method according to polymerization method in O / W type emulsion described in JP-A-2005-314538)
1.5 mmol of di-2-ethylhexyl sodium sulfosuccinate was dissolved in 50 mL of toluene, and further 100 mL of ion-exchanged water was added and stirred until emulsification was maintained at 20 ° C. To the obtained emulsion, 21.2 mmol of pyrrole monomer was added and stirred for 30 minutes, and then 50 mL (corresponding to 6 mmol) of a 0.12M ammonium persulfate aqueous solution was added dropwise little by little and reacted for 4 hours. After completion of the reaction, the organic phase was recovered, washed several times with ion-exchanged water, and black conductive fine particles (average particle size 60 nm) were obtained in a state dispersed in toluene.

Test example 1
The conductive fine particles obtained in Examples 1 to 14 and Comparative Examples 1, 2, and 5 were made into a conductive paint using the same method, and the characteristics of the conductive thin film obtained by applying the conductive paint to a glass plate Was evaluated. The evaluation was performed according to the following criteria for the resistance value (Ω) of the conductive coating film, the resistance value change with time of the conductive coating film, and the dispersion stability of the conductive paint.
Resistance value change over time The time it took for the resistance value to increase by one digit ◎: 3 months or more ○: 2 months or more △: 1 month or more and 2 months or less ×: 1 month or less dispersion stability ◎: 2 months or more stable dispersion ○: Stable dispersion within 1 month to 2 months Δ: Aggregation occurs and precipitates in 1 week x: Aggregates immediately after dispersion Table 2 shows the evaluation results.
In the table, A and B described in "Polymerization method", C and D described in "Anion" of "Surfactant", E described in "Nonion" and F described in "Dopant" are respectively Means the following:
A: Polymerization method in which a polymerization reaction is started in an aqueous medium, and an organic solvent is added and a polymerization reaction is further performed at a specific polymerization rate B: O / W type described in JP-A-2005-314538 Polymerization method C in accordance with the polymerization method in an emulsion of di-2-ethylhexyl sulfosuccinate (anionic surfactant: Perex OT-P)
D: Nonionic surfactant Emulgen 409P
E: Sodium dodecylbenzenesulfonate In Tables 1 to 14 and Comparative Examples 1 and 2, “polymerization rate” indicates the polymerization rate (%) of polypyrrole before the addition of the organic solvent.
In addition, “average particle size before addition” in the table means the average particle size of polypyrrole before adding the organic solvent, and “average particle size after reaction” is the average of polypyrrole after recovery of the organic phase. Means particle size.
The average particle diameter of polypyrrole was measured by a laser Doppler method using Nanotrac UPA150 manufactured by Microtrac, and the polymerization rate of polypyrrole was determined by measuring residual monomers using gas chromatography. Calculated from the ratio.

As shown in Examples 1 to 8, the type of organic solvent used (aliphatic ester, aromatic solvent, ketone, cyclic saturated hydrocarbon, chain saturated hydrocarbon, chain saturated alcohol, aromatic The resistance value change with time and the dispersion stability were equally excellent regardless of the group of aliphatic esters and aliphatic ethers).
As shown in Examples 9, 10 and 12, when a dopant (sodium dodecylbenzenesulfonate) was added in an aqueous medium, the surfactant used was an anionic surfactant (Example 9), a nonionic surfactant. Regardless of the agent (Example 10), anionic surfactant + nonionic surfactant (Example 12), particularly excellent resistance value aging and dispersion stability were exhibited.
As shown in Examples 10 and 11, the same applies even when a nonionic surfactant (Example 10), an anionic surfactant + nonionic surfactant (Example 11) is used instead of the anionic surfactant. In addition, excellent resistance value change with time and dispersion stability were exhibited.
As shown in Example 13, when the polymerization rate at the time of adding the organic solvent was 10%, excellent resistance value aging and dispersion stability were shown, whereas, as shown in Comparative Example 2, When the polymerization rate when the organic solvent was added was 5%, both the resistance value change with time and the dispersion stability deteriorated.
As shown in Example 14, when the polymerization rate at the time of adding the organic solvent was 60%, excellent resistance value aging and dispersion stability were shown, whereas, as shown in Comparative Example 1, When the polymerization rate at the time of adding the organic solvent was 70%, both the resistance value change with time and the dispersion stability deteriorated.
As shown in Comparative Example 5, when the polymerization method in the O / W type emulsion described in JP-A-2005-314538 was used, the dispersion stability was good, but the resistance value changed with time. Was inferior.
As shown in Comparative Example 3, when the toluene of Comparative Example 5 was changed to butyl acetate, the polymerization reaction itself did not proceed.
As shown in Comparative Example 4, when the anionic surfactant in Comparative Example 5 was changed to a nonionic surfactant, the polymerization reaction itself did not proceed.

It is the figure which modeled and compared operation by the manufacturing method of the polypyrrole microparticles | fine-particles of this invention, and operation by the manufacturing method of the polypyrrole microparticles described in Unexamined-Japanese-Patent No. 2005-314538. It is a schematic diagram of the production | generation process of the polypyrrole particle | grains assumed in the manufacturing method of the polypyrrole fine particle of Unexamined-Japanese-Patent No. 2005-314538. It is a schematic diagram of the production | generation process of the polypyrrole fine particle assumed in the manufacturing method of the polypyrrole fine particle of this invention. It is a graph which shows the relationship between the polymerization rate (%) of the polypyrrole in an aqueous medium, and the average particle diameter (nm) of the polypyrrole obtained at that time.

Explanation of symbols

1: pyrrole monomer 2: surfactant 3: polypyrrole fine particle 4: oxidizing agent

Claims (3)

A method for producing polypyrrole fine particles nano-dispersed in an organic solvent layer,
Polymerization is initiated in an aqueous medium containing an amount of pyrrole and / or pyrrole derivative, anionic surfactant and / or nonionic surfactant, and an oxidizing agent that can be solubilized in the aqueous medium, and the polymerization rate of the polypyrrole is 10 to 10%. A method in which an organic solvent is added to the polymerization system at a point of 60%, polymerization is further advanced, and then the organic solvent layer of the two separated layers is recovered. 2. The method of producing polypyrrole fine particles according to claim 1, wherein the addition of the organic solvent is performed when the particle size of the polypyrrole is 100 nm or less. The method for producing fine polypyrrole particles according to claim 1, wherein a dopant is present in the aqueous medium.

Images