JP4470175B2 - Conductive fine particle aqueous dispersion and process for producing the same - Google Patents

Description

  The present invention relates to a conductive fine particle aqueous dispersion which can be used as a raw material for conductive paints. Specifically, it exhibits excellent dispersion stability without causing sedimentation over a long period of time, and when used as a conductive paint, it has low resistance and high transparency, and has good adhesion to the substrate. Further, the present invention relates to a conductive fine particle aqueous dispersion capable of forming a conductive thin film that maintains a low resistance value without depending on humidity.

  Polypyrrole, which is a kind of conductive polymer, has high conductive performance and is stable in the air, so conductive paint, rust preventive paint, semiconductor material, electrolyte for capacitors, hole transport material for organic EL elements, two It is expected to be used for electrode materials for secondary batteries. For example, it is known that polypyrrole incorporating chloride ions as a dopant can be easily obtained by dispersing pyrrole monomer in water and polymerizing with ferric chloride as a catalyst. However, the polypyrrole thus obtained is a black powdery agglomerate, not only insoluble in any solvent, but also impossible to melt by heating, handling is extremely difficult, and its field of use has been limited. .

  For the purpose of improving the molding processability of polypyrrole, a method is known in which polypyrrole is finely dispersed in an aqueous solvent using polyvinyl alcohol (PVA), a surfactant or the like to produce an apparently uniform aqueous dispersion. (For example, refer to Patent Document 1). This method consists of polymerizing pyrrole monomers in the presence of PVA and optionally nonionic surfactants and / or anionic surfactants, dispersing action of PVA which is a water-soluble polymer, and interfacial tension by surfactants. The polypyrrole obtained by polymerization is finely dispersed by the lowering action. The amount of PVA used here is 2 to 500% by weight, preferably 10 to 200% by weight, based on the pyrrole monomer, and the addition of 50 to 200% by weight of PVA is exemplified.

Further, a conductive thin film is obtained by adding a hydrophilic binder resin to polypyrrole fine particles dispersed in a hydrophilic solvent using a polymer dispersant and / or a dopant, and coating the obtained resin composition on a substrate. It is also known to form (see, for example, Patent Document 2).
Japanese Patent Publication No. 7-78116 JP 2001-334598 A

  However, in the conductive fine particle aqueous dispersion using a dispersant / surfactant such as polyvinyl alcohol as in Patent Document 1, the amount of the dispersant / surfactant used is large with respect to the pyrrole monomer. Since it is a component that hinders electrical conduction, it is difficult to reduce the resistance value of the obtained aqueous dispersion. Therefore, the conductive paint manufactured from the water-based dispersion of the prior art cannot obtain a desired resistance value with a thin film thickness when a conductive thin film is formed, and several tens of μm to achieve a sufficient resistance value. The above film thickness was necessary. However, such a thin film having a large thickness is a black one having no transparency, and the appearance is remarkably impaired. Furthermore, since the dispersant / surfactant is contained in a large amount, there is a problem that the ionic conductivity is expressed by the influence of moisture in the air, and the resistance value of the conductive thin film changes depending on the humidity. .

Further, in the method disclosed in Patent Document 2, there are many steps required for coating, such as a step of dispersing polypyrrole fine particles with a polymer dispersant and / or a dopant, a step of mixing a hydrophilic binder resin, etc., and the productivity is low. Met.

  Accordingly, an object of the present invention is to provide a conductive fine particle aqueous dispersion which can be stably dispersed over a long period of time, achieves a low resistance value and high transparency when a conductive thin film is formed, and has excellent adhesion to a substrate. It is to provide.

  As a result of intensive studies, the present inventor conducted a conductive oxidative polymerization of a monomer that forms a conductive polymer in an aqueous solvent in the presence of an amphiphilic comb-shaped polyurethane compound. It has been found that an aqueous fine particle dispersion can be obtained. This is because when the polyurethane compound is allowed to coexist during chemical oxidative polymerization of a monomer, the resulting conductive polymer and the polyurethane compound form a complex, and the complex is at least part of the surface of the conductive polymer. Is expected to be a structure covered with the polyurethane compound.

Therefore, the present invention
Conductive fine particles, which are a composite of a conductive polymer and an amphiphilic comb-shaped polyurethane compound, are dispersed in an aqueous solvent. In the conductive fine particles, at least a part of the surface of the conductive polymer is made of the polyurethane. The present invention relates to an aqueous conductive fine particle dispersion characterized by being coated with a compound.

［式中、
Ｒ₁は、炭素原子数１ないし２０のアルキル基を表し、
Ｒ₂は、−（ＣＨ₂ＣＨ₂Ｏ）_p−Ｃ_nＨ_2n+1、−（ＣＨ₂ＣＨ₂Ｏ）_p−フェニル基、または−（ＣＨ₂ＣＨ₂Ｏ）_p−ＣＯＣＨ₃を表し、
ｎは、１ないし１８の数を表し、
ｐは、１ないし１００の数を表し、
Ｘは、

を表し、そして
Ｙは、０．４ないし１．０の数を表す。］で表される構造単位を含んでなることを特徴とする前記導電性微粒子水系分散体
に関する。 A preferred embodiment of the conductive fine particle aqueous dispersion according to the present invention is:
The conductive fine particle aqueous dispersion, wherein the conductive polymer is a polymer of at least one monomer selected from the group consisting of pyrrole, aniline, thiophene and derivatives thereof, and the polyurethane compound Is the following formula I

[Where:
R ₁ represents an alkyl group having 1 to 20 carbon atoms,
R ₂ represents — (CH ₂ CH ₂ O) _p —C _n H _{2n + 1} , — (CH ₂ CH ₂ O) _p -phenyl group, or — (CH ₂ CH ₂ O) _p —COCH ₃ ,
n represents a number from 1 to 18,
p represents a number from 1 to 100;
X is

And Y represents a number from 0.4 to 1.0. ] It is related with the said electroconductive fine particle aqueous dispersion characterized by including the structural unit represented by these.

The present invention also provides
The present invention relates to a method for producing a conductive fine particle aqueous dispersion, wherein a monomer that forms a conductive polymer is chemically oxidatively polymerized in an aqueous solvent in the presence of an amphiphilic comb-shaped polyurethane compound.

［式中、
Ｒ₁は、炭素原子数１ないし２０のアルキル基を表し、
Ｒ₂は、−（ＣＨ₂ＣＨ₂Ｏ）_p−Ｃ_nＨ_2n+1、−（ＣＨ₂ＣＨ₂Ｏ）_p−フェニル基、または−（ＣＨ₂ＣＨ₂Ｏ）_p−ＣＯＣＨ₃を表し、
ｎは、１ないし１８の数を表し、
ｐは、１ないし１００の数を表し、
Ｘは、

を表し、そして
Ｙは、０．４ないし１．０の数を表す。］で表される構造単位を含んでなることを特徴とする前記導電性微粒子水系分散体の製造方法
に関する。 A preferred embodiment of the method for producing a conductive fine particle aqueous dispersion according to the present invention is:
The monomer is at least one selected from the group consisting of pyrrole, aniline, thiophene and derivatives thereof, and the polyurethane compound has the following formula I:

[Where:
R ₁ represents an alkyl group having 1 to 20 carbon atoms,
R ₂ represents — (CH ₂ CH ₂ O) _p —C _n H _{2n + 1} , — (CH ₂ CH ₂ O) _p -phenyl group, or — (CH ₂ CH ₂ O) _p —COCH ₃ ,
n represents a number from 1 to 18,
p represents a number from 1 to 100;
X is

And Y represents a number from 0.4 to 1.0. ] It is related with the manufacturing method of the said electroconductive fine particle aqueous dispersion characterized by including the structural unit represented by these.

  In the conductive fine particle aqueous dispersion of the present invention, the conductive fine particle is a composite of a conductive polymer and an amphiphilic comb-shaped polyurethane compound, and at least a part of the surface of the conductive polymer is covered with the polyurethane compound. Since it is covered, the conductive fine particles can be stably dispersed in the aqueous solvent. Therefore, even when stored for a long period of time, the conductive fine particles do not settle, and since they are comb-shaped, they have excellent dispersion stability over a long period.

  In addition, since the conductive paint using the conductive fine particle aqueous dispersion of the present invention as a raw material does not contain a large amount of a dispersant / surfactant component that hinders electrical conduction such as polyvinyl alcohol, it is low when a conductive thin film is formed. Since the resistance value can be achieved and the necessary resistance value can be obtained with a thin film thickness, the transparency of the conductive thin film is also increased. In addition, since it does not contain components such as surfactants that are affected by moisture in the air, the formed conductive thin film does not exhibit humidity dependency. Furthermore, the adhesion between the conductive thin film to be formed and the substrate is improved when applied to the substrate due to the structure of the conductive fine particles described above.

The monomer that forms the conductive polymer used in the present invention may be at least one selected from the group consisting of pyrrole, aniline, thiophene, and derivatives thereof. For example, as pyrrole derivatives, 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-diphenylamino Pyrrole, 3-methylphenylamino pillow , 3-phenyl naphthyl amino pyrrole, and the like. Examples of aniline derivatives include o-methylaniline, m-methylaniline, o-ethylaniline, m-ethylaniline, o-ethoxyaniline, m-butylaniline, m-hexylaniline, m-octylaniline, 2, 3-dimethylaniline, 2,5-dimethylaniline, 2,5-dimethoxyaniline, o-cyanoaniline, 2,5-dichloroaniline, 2-bromoaniline, 5-chloro-2-methoxyaniline, 3-phenoxyaniline, etc. Is mentioned. Furthermore, as thiophene derivatives, 3-methylthiophene, 3,4-dimethylthiophene, 3-hexylthiophene, 3-stearylthiophene, 3-bromothiophene, 3-methoxydiethoxymethylthiophene, 3-phenylthiophene, 3-benzyl Examples include thiophene and 3-methyl-4-phenylthiophene. Particularly preferred is pyrrole.

  The conductive fine particle of the present invention is a composite of a conductive polymer obtained by chemical oxidative polymerization of the monomer and an amphiphilic comb-shaped polyurethane compound, and at least one surface of the conductive polymer such as polypyrrole. Part is coated with the polyurethane compound. This is expected due to the hydrophobic interaction between the main chain of the polyurethane compound and the polypyrrole particles. Since the polyurethane compound contains a large number of adsorption points, the bond between them is relatively strong and the complex does not easily desorb. The extent to which the surface of the conductive polymer is covered with the polyurethane compound can vary depending on the amount of the polyurethane compound to be present and the molecular weight of the polyurethane compound.

［式中、
Ｒ₁は、炭素原子数１ないし２０のアルキル基を表し、
Ｒ₂は、−（ＣＨ₂ＣＨ₂Ｏ）_p−Ｃ_nＨ_2n+1、−（ＣＨ₂ＣＨ₂Ｏ）_p−フェニル基、または−（ＣＨ₂ＣＨ₂Ｏ）_p−ＣＯＣＨ₃を表し、
ｎは、１ないし１８の数を表し、
ｐは、１ないし１００の数を表し、
Ｘは、

を表し、そして
Ｙは、０．４ないし１．０の数を表す。］で表される構造単位を含むポリウレタン化合物が好ましい。 A variety of polyurethane compounds can be used as the polyurethane compound, but a preferred polyurethane compound is a comb-shaped polyurethane compound.

[Where:
R ₁ represents an alkyl group having 1 to 20 carbon atoms,
R ₂ represents — (CH ₂ CH ₂ O) _p —C _n H _{2n + 1} , — (CH ₂ CH ₂ O) _p -phenyl group, or — (CH ₂ CH ₂ O) _p —COCH ₃ ,
n represents a number from 1 to 18,
p represents a number from 1 to 100;
X is

And Y represents a number from 0.4 to 1.0. The polyurethane compound containing the structural unit represented by this is preferable.

For example, the comb-shaped polyurethane compound represented by the formula I generates a diol from a corresponding acrylate derivative and diethanolamine by Michael Addition, and uses the diol and, for example, isophorone diisocyanate using a catalyst such as dibutyltin dilaurate. It can be produced by refluxing natto and the like.

  The conductive fine particles of the present invention can be produced by chemical oxidative polymerization of a monomer that forms a conductive polymer in an aqueous solvent in the presence of an amphiphilic comb-shaped polyurethane compound. In the chemical oxidative polymerization, the concentration of the monomer that forms the conductive polymer present in the aqueous solvent is preferably 0.01 to 10% by weight, more preferably 0.1 to 2% by weight. The amount of the polyurethane compound to be coexisted during the chemical oxidative polymerization is, for example, 1 to 500 parts by weight, preferably 5 to 200 parts by weight, with respect to 100 parts by weight of the monomer. When the polyurethane compound is increased beyond this range, the resistance value in the case of a conductive thin film is increased. On the other hand, when the polyurethane compound is less than this range, desired effects cannot be obtained in terms of dispersion stability, bonding properties, and the like. .

  The oxidizing agent used in the chemical oxidative polymerization is not particularly limited as long as it can chemically oxidize pyrrole, aniline, thiophene and their derivatives. For example, inorganic acids such as sulfuric acid, nitric acid and chlorosulfonic acid, organic acids such as alkylbenzenesulfonic acid and alkylnaphthalenesulfonic acid, peroxides such as potassium persulfate, ammonium persulfate and hydrogen peroxide, ferric chloride Metal halides such as aluminum chloride, halogen acids such as iodic acid and potassium perchlorate and salts thereof, transition metal compounds such as potassium permanganate, and the like can be used. These may be used alone or in combination. Particularly preferred is ammonium persulfate. Moreover, the addition amount of this oxidizing agent is 0.01-7 mol with respect to 1 mol of monomers to superpose | polymerize, Preferably it is 0.1-4 mol.

  The aqueous solvent is not particularly limited as long as it is an inert solvent for the polymerization reaction. Particularly preferred is water. Moreover, as long as this dispersion stability is not impaired, alcohols such as methyl alcohol and isopropyl alcohol and other organic solvents can be mixed and used.

  Moreover, a dopant can also be introduce | transduced in a polymer by making a doping agent (dopant) coexist in a reaction system in the case of superposition | polymerization. The dopant to be used is not particularly limited as long as it is a commonly used acceptor-type dopant, for example, halogen such as chlorine, bromine and iodine, Lewis acid such as phosphorus pentafluoride, proton acid such as hydrogen chloride and sulfuric acid. Transition metal chlorides such as ferric chloride, and transition metal compounds such as silver perchlorate and silver fluoborate. In addition, a part of the oxidizing agent used for the polymerization may be taken into the polymer and serve as a dopant. The introduction of such a dopant is not essential in the present invention, but the introduction of a dopant can further improve the conductive performance.

  In the conductive fine particle aqueous dispersion of the present invention, since the surface of the conductive polymer is covered with the amphiphilic comb polyurethane compound, the conductive fine particles can stably maintain a dispersed state for a long period of time. The particle size does not change with time. In addition, since the polyurethane compound is compounded with the conductive polymer, sufficient dispersion stability can be achieved with a small amount of the polyurethane compound. Furthermore, when the conductive fine particle aqueous dispersion is applied on the base material, the polyurethane compound acts as a binder to improve the adhesion.

［式中、Ｒ₁は−Ｃ₁₈Ｈ₃₇を表し、Ｒ₂は−（ＣＨ₂ＣＨ₂Ｏ）₂₃ＣＨ₃を表し、Ｘは

を表し、そしてＹは０．４９の数を表す。］で表される化合物であり、またポリウレタン化合物Ｂは、上記式中、Ｒ₁は−Ｃ₄Ｈ₉を表し、Ｒ₂は−（ＣＨ₂ＣＨ₂Ｏ）₉ＣＨ₃を表し、Ｘは−（ＣＨ₂）₆−を表し、そしてＹは０．５０の数を表す化合物である。 Hereinafter, the present invention will be described in more detail with reference to examples. In the following examples, polyurethane compound A has the following formula:

[Wherein R ₁ represents —C ₁₈ H ₃₇ , R ₂ represents — (CH ₂ CH ₂ O) ₂₃ CH ₃ , and X represents

And Y represents a number of 0.49. In addition, in the above formula, R ₁ represents —C ₄ H ₉ , R ₂ represents — (CH ₂ CH ₂ O) ₉ CH ₃ , and X represents — (CH ₂ ) ₆ — represents a compound in which Y represents a number of 0.50.

  65 mg of pyrrole and 32.5 mg of polyurethane compound A represented by the formula I were added to 40 g of ion-exchanged water and stirred for 15 minutes, and 10 mL of an aqueous ammonium persulfate solution (0.12M) was added to perform chemical oxidative polymerization. A black conductive fine particle aqueous dispersion was obtained.

  A conductive fine particle aqueous dispersion was obtained in the same manner as in Example 1 except that the amount of polyurethane compound A added was 6.5 mg.

  A conductive fine particle aqueous dispersion was obtained in the same manner as in Example 1 except that the amount of polyurethane compound A added was 0.13 mg.

  A conductive fine particle aqueous dispersion was obtained in the same manner as in Example 1 except that the polyurethane compound B was added instead of the polyurethane compound A.

  A conductive fine particle aqueous dispersion was obtained in the same manner as in Example 1 except that aniline was added instead of pyrrole as a material for forming the conductive polymer.

Comparative Example 1
Chemical oxidative polymerization was carried out in the same manner as in Example 1 except that the polyurethane compound A was not added. The conductive polymer produced by polymerization became an aggregate and could not be dispersed in water, and an aqueous dispersion could not be obtained.

Comparative Example 2
A conductive fine particle aqueous dispersion was obtained in the same manner as in Example 1 except that 65 mg of sodium dodecylbenzenesulfonate was added in place of the polyurethane compound A.

Comparative Example 3
Chemical oxidative polymerization was carried out in the same manner as in Example 1 except that 0.65 g (solid content 32.5 mg) of an aqueous polyvinyl alcohol solution (completely saponified type, polymerization degree 1700, concentration 5%) was added instead of the polyurethane compound A. went. The conductive polymer produced by polymerization became an aggregate and could not be dispersed in water, and an aqueous dispersion could not be obtained.

The conductive fine particle aqueous dispersions obtained in Examples 1 to 5 and Comparative Example 2 and the conductive thin films formed therefrom were evaluated according to the following tests 1 to 6.
<Test 1: Average particle size>
An average particle size (nm) was measured in a monodisperse mode using a nanotrack particle size distribution measuring device UPA-EX150 (manufactured by Nikkiso Co., Ltd.).
<Test 2: Dispersion stability>
The sample whose absorbance was measured in advance was centrifuged at 5000 rpm for 10 minutes using a centrifugal automatic particle size distribution analyzer CAPA-500 (manufactured by Horiba, Ltd.). The absorbance of the sample was measured again after centrifugation, and the dispersion stability of the sample was determined from the relative absorbance. It is considered that the higher the dispersion stability of the sample, the smaller the amount of conductive fine particles that settle by centrifugation. Therefore, the smaller the relative absorbance value is, that is, the smaller the absorbance change before and after centrifugation, the higher the dispersion stability of the sample.
<Test 3: Surface resistance value>
The sample was uniformly applied onto the substrate using a bar coater # 8 and dried to form a conductive thin film. About this electroconductive thin film, the surface resistance value ((omega | ohm)) was measured using the Hiresta resistance meter and the Loresta resistance meter (each made by Mitsubishi Chemical Corporation) in the atmosphere adjusted to 50% of humidity.
<Test 4: Transparency>
For the conductive thin film formed in the same manner as in Test 3, the light transmittance at 550 nm (%) using a spectrophotometer (manufactured by JASCO Corporation) with a base material on which the conductive thin film is not formed as a reference. Was measured. The higher the light transmittance, the higher the transparency of the conductive thin film.
<Test 5: Adhesion>
The adhesiveness of the conductive thin film formed in the same manner as in Test 3 was measured according to JIS K5600-5-6. The obtained measurement results were classified into 0-5 grades. Grade 0 indicates the best adhesion and Grade 5 indicates the poorest adhesion.
<Test 6: Humidity dependency>
Whether the surface resistance of the conductive thin film formed in the same manner as in test 3 is measured in the same manner as in test 3 in an atmosphere adjusted to a humidity of 10%, 50%, and 100%. Decided whether or not.

The results of Tests 1-6 are shown in Table 1 below.

As is clear from the above results, the conductive fine particle aqueous dispersion of the present invention has a smaller average particle size and higher dispersion stability than the conventional one. When a conductive thin film is formed, the surface resistance value is low with a thin film thickness, the transparency is high, the adhesiveness with the base material is excellent, and the temperature dependency of the surface resistance value is not recognized.
On the other hand, in the prior art, it is difficult to obtain an aqueous dispersion by dispersing conductive fine particles in the first place, and even if an aqueous dispersion is obtained, the dispersion stability and the conductive thin film are formed. The surface resistance value, transparency and adhesion are not sufficient, and the surface resistance value shows humidity dependency.

Claims (6)

Conductive fine particles, which are a composite of a conductive polymer and an amphiphilic comb-shaped polyurethane compound, are dispersed in an aqueous solvent. In the conductive fine particles, at least a part of the surface of the conductive polymer is made of the polyurethane. A conductive fine particle aqueous dispersion, wherein the compound is coated. The conductive fine particle aqueous dispersion according to claim 1, wherein the conductive polymer is a polymer of at least one monomer selected from the group consisting of pyrrole, aniline, thiophene and derivatives thereof. . The polyurethane compound has the formula I

[Where:
R ₁ represents an alkyl group having 1 to 20 carbon atoms,
R ₂ represents — (CH ₂ CH ₂ O) _p —C _n H _{2n + 1} , — (CH ₂ CH ₂ O) _p -phenyl group, or — (CH ₂ CH ₂ O) _p —COCH ₃ ,
n represents a number from 1 to 18,
p represents a number from 1 to 100;
X is

And Y represents a number from 0.4 to 1.0. The conductive fine particle aqueous dispersion according to claim 1, comprising a structural unit represented by the formula: A method for producing a conductive fine particle aqueous dispersion, wherein a monomer that forms a conductive polymer is chemically oxidatively polymerized in an aqueous solvent in the presence of an amphiphilic comb-shaped polyurethane compound. The method for producing a conductive fine particle aqueous dispersion according to claim 4, wherein the monomer is at least one selected from the group consisting of pyrrole, aniline, thiophene, and derivatives thereof. The polyurethane compound has the formula I

[Where:
R ₁ represents an alkyl group having 1 to 20 carbon atoms,
R ₂ represents — (CH ₂ CH ₂ O) _p —C _n H _{2n + 1} , — (CH ₂ CH ₂ O) _p -phenyl group, or — (CH ₂ CH ₂ O) _p —COCH ₃ ,
n represents a number from 1 to 18,
p represents a number from 1 to 100;
X is

And Y represents a number from 0.4 to 1.0. The manufacturing method of the electroconductive fine particle aqueous dispersion of Claim 4 characterized by including the structural unit represented by these.