JP2021093377A - Method for producing conductive particle - Google Patents

Abstract

To provide composite particles which can sufficiently exhibit a function as a filler and function as a conductivity imparting agent, and a conductive resin composition in which conductive particles sufficiently exhibit a function as a filler.SOLUTION: Conductive particles contain a conductive composite body containing a π-conjugated-based conductive polymer and polyanion, and base material particles. The conductive particles preferably contain coated particles in which at least a surface of the base material particles is coated with the conductive composite body. A conductive resin composition contains the conductive particles and a binder resin.SELECTED DRAWING: None

Description

The present invention relates to conductive particles containing a π-conjugated conductive polymer, a method for producing the same, and a conductive resin composition.

Resin molded products are widely used in various fields. In the resin used for the molded product, a particulate filler may be blended. The purpose of blending the filler in the resin is to adjust mechanical properties, improve heat resistance, improve durability, improve wear resistance, reduce costs, and the like.
Further, the resin may contain metal particles or carbon particles to impart conductivity (Patent Documents 1 and 2). The conductive resin is used, for example, as a material for producing an antistatic molded product, an electromagnetic wave absorbing molded product, or the like.

JP-A-2010-189565 Japanese Unexamined Patent Publication No. 2011-184618

However, it is difficult for the metal particles or carbon particles blended in the resin to exhibit the same function as the filler, and rather, the mechanical properties tend to be deteriorated.
An object of the present invention is to provide conductive particles that can sufficiently exert a function as a filler and also function as a conductivity-imparting agent, and a method for producing the same. An object of the present invention is to provide a conductive resin composition in which conductive particles sufficiently exert a function as a filler.

The present invention includes the following aspects.
[1] A conductive particle containing a conductive composite containing a π-conjugated conductive polymer and a polyanion, and substrate particles.
[2] The conductive particle according to [1], which contains coated particles in which at least a part of the surface of the base particle is coated with the conductive composite.
[3] The conductive particle according to [1] or [2], wherein the median diameter is 0.01 μm or more and 100 μm or less.
[4] The base particles are particles containing one or more selected from the group consisting of calcium carbonate, glass, silica, calcium hydroxide, acrylic resin, and polyamide, [1] to [3]. ] The conductive particle according to any one of.
[5] The conductive particle according to any one of [1] to [4], wherein the π-conjugated conductive polymer is poly (3,4-ethylenedioxythiophene).
[6] The conductive particle according to any one of [1] to [5], wherein the polyanion is polystyrene sulfonic acid.
[7] The conductive particle according to any one of [1] to [6], further containing an antioxidant.
[8] A conductive resin composition containing the conductive particles according to any one of [1] to [7] and a binder resin.
[9] The binder resin contains at least one selected from the group consisting of silicone resin, epoxy resin, acrylic resin, polyester resin, polyurethane resin, polyolefin resin, urea resin, polyamide resin, and polystyrene resin [8]. ] The conductive resin composition according to.
[10] The conductive resin composition according to [8] or [9], which further contains an antioxidant.

[11] A mixed solution is prepared by mixing an aqueous dispersion of a conductive complex containing a π-conjugated conductive polymer and a polyanion with raw material particles, and then water is removed to prepare the conductive complex. A method for producing conductive particles, which forms a solid substance containing the raw material particles and pulverizes the solid substance.
[12] The method for producing conductive particles according to [11], wherein the method for removing water is heat drying.
[13] When preparing the mixed solution, an organic solvent having a boiling point of 100 ° C. or higher at standard atmosphere is further mixed with the aqueous dispersion of the conductive composite and the raw material particles, [11] or [ 12] The method for producing conductive particles according to the above method.
[14] The method for producing conductive particles according to [13], wherein the organic solvent is propylene glycol.
[15] π-conjugated conductive polymer and polyanion-containing conductive composite aqueous dispersion and raw material particles are mixed to prepare a mixed liquid, and then an organic solvent is added to prepare the conductive composite. A method for producing conductive particles, wherein a solid material containing the conductive composite and the raw material particles is formed by precipitating the solid material, and the solid material is recovered.
[16] The method for producing conductive particles according to [15], wherein the solid substance is pulverized.
[17] The method for producing conductive particles according to [15] or [16], wherein the organic solvent is an alcohol solvent.
[18] The method for producing conductive particles according to [17], wherein the alcohol solvent is isopropanol.

The conductive particles of the present invention can sufficiently exert a function as a filler and also function as a conductivity-imparting agent.
According to the method for producing conductive particles of the present invention, the conductive particles can be easily produced.
In the conductive resin composition of the present invention, the conductive particles fully exhibit the function as a filler.

<Conductive particles>
One aspect of the conductive particles of the present invention will be described.
The conductive particles of this embodiment are particles containing a conductive composite and base particles. The conductive complex contains a π-conjugated conductive polymer and a polyanion. The π-conjugated conductive polymer and polyanion will be described later.
The conductive particles of this embodiment are aggregates (powder) of a plurality of particles. The conductive particles of this embodiment preferably contain coated particles in which at least a part of the surface of the base particles is coated with the conductive composite. The coated particles can more exert both a function as a filler and a function as a conductivity-imparting agent.
For the above reason, it is preferable that the content of the coated particles in the conductive particles is large. For example, in an image (TEM image) obtained by photographing conductive particles using a transmission electron microscope (TEM), when the area of all particles having a particle size of 1 nm or more contained in the conductive particles is set to 100 area%, the coated particles. The area ratio of the particles is preferably 50% or more. When the area ratio of the coated particles in the TEM image is equal to or greater than the lower limit value, the conductive particles can more effectively exhibit both the function as a filler and the function as a conductivity-imparting agent.

In the conductive particles of this embodiment, when at least a part of the surface of the base particles is coated with the conductive composite, the coverage of the conductive composite on the surface of the base particles is 50% or more and 100% or less. It is preferably 80% or more and 100% or less, and more preferably 90% or more and 100% or less. When the coverage is at least the lower limit value, it becomes easier to impart conductivity when the conductive particles are blended with the resin.
The coverage is the ratio of the area of the base particles covered with the conductive complex when the total area of the surface of the base particles is 100%. This coverage is an average value obtained by determining the coverage of 10 or more conductive particles and averaging the coverage.
The coverage can be measured by the following method.
Images of conductive particles are obtained using a transmission electron microscope (TEM). Area than the image, the area S ₀ of the surface of the substrate particles, the substrate particles, the area S ₁ is covered by a conductive _composite, or, where the base particles, not covered by the conductive composite Measure S _2. The coverage can be obtained from the formula (area S ₁ / area S _{0) × 100.} Alternatively, the coverage can be obtained from the formula of 100- {the area S ₂ / the area S _{0) × 100}.}
In this method, the coverage is obtained from a two-dimensional image, and the coverage is not a direct measurement of the coverage of three-dimensional particles, but correlates with the coverage of three-dimensional particles.

When the surface of the base particle is not coated with the conductive composite, the conductive particle includes a powder in which the base particle and the conductive composite are independently present and are mixed thereto. Examples of the conductive particles in which the surface of the base material particles is not coated with the conductive composite are, for example, particles in which the base material particles and the conductive composite particles are integrated, and the base material particles of the conductive composite. Examples thereof include particles in which lumps are attached and integrated.

Conductive particles preferably has a median diameter of 50% particle size _{D 50} is 0.01μm or 100μm or less, more preferably 0.1μm or 50μm or less, it is 0.1μm or more 30μm or less Is even more preferable. When the median diameter of the conductive particles is at least the lower limit value, the function as a filler can be more exerted, and when it is at least the upper limit value, it becomes easy to mix with the resin.
The median diameter of the conductive particles is 50% particle diameter D ₅₀ was determined by particle size measurement by dynamic light scattering method.
The conductive particles have a 10% particle diameter D ₁₀ of preferably 0.01 μm or more and 10 μm or less, more preferably 0.01 μm or more and 5 μm or less, and further preferably 0.01 μm or more and 1 μm or less.
The conductive particles have a 90% particle diameter D ₉₀ of preferably 1 μm or more and 100 μm or less, more preferably 1 μm or more and 70 μm or less, and further preferably 1 μm or more and 40 μm or less.
The smaller the median diameter of the conductive particles, the larger the specific surface area of the conductive particles, so that it becomes easier to impart conductivity.
Both the 10% particle size and the 90% particle size of the conductive particles are determined by measuring the particle size by the dynamic light scattering method. D ₅₀ is greater than _{D 10 and} less than _{D 90.}

(Conductive complex)
The conductive complex constituting the conductive particles of this embodiment contains a π-conjugated conductive polymer and a polyanion having an anion group. The polyanion coordinates with the π-conjugated conductive polymer, and the anion group of the polyanion is doped with the π-conjugated conductive polymer to form a conductive composite having conductivity.
In the poly anion, all the anion groups are not doped in the π-conjugated conductive polymer and have an extra anion group. Since the excess anion group is a hydrophilic group, the conductive complex has water dispersibility.

[Π-conjugated conductive polymer]
The π-conjugated conductive polymer is not particularly limited as long as it has the effect of the present invention as long as it is an organic polymer whose main chain is composed of a π-conjugated system. Conductive polymer, polyacetylene-based conductive polymer, polyphenylene-based conductive polymer, polyphenylene vinylene-based conductive polymer, polyaniline-based conductive polymer, polyacene-based conductive polymer, polythiophene vinylene-based conductive polymer, and Examples thereof include these copolymers. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophenes and polyaniline-based conductive polymers are preferable, and from the viewpoint of conductivity, polythiophene-based conductive polymers are more preferable.

Examples of the polythiophene-based conductive polymer include polythiophene, poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), poly (3-butylthiophene), and poly (3-hexylthiophene). , Poly (3-heptylthiophene), Poly (3-octylthiophene), Poly (3-decylthiophene), Poly (3-dodecylthiophene), Poly (3-octadecylthiophene), Poly (3-bromothiophene), Poly (3-Chlorothiophene), poly (3-iodothiophene), poly (3-cyanothiophene), poly (3-phenylthiophene), poly (3,4-dimethylthiophene), poly (3,4-dibutylthiophene) , Poly (3-hydroxythiophene), Poly (3-methoxythiophene), Poly (3-ethoxythiophene), Poly (3-butoxythiophene), Poly (3-hexyloxythiophene), Poly (3-Heptyloxythiophene) , Poly (3-octyloxythiophene), Poly (3-decyloxythiophene), Poly (3-dodecyloxythiophene), Poly (3-octadecyloxythiophene), Poly (3,4-dihydroxythiophene), Poly (3) , 4-dimethoxythiophene), poly (3,4-diethoxythiophene), poly (3,4-dipropoxythiophene), poly (3,4-dibutoxythiophene), poly (3,4-dihexyloxythiophene) , Poly (3,4-diheptyloxythiophene), Poly (3,4-dioctyloxythiophene), Poly (3,4-didecyloxythiophene), Poly (3,4-didodecyloxythiophene), Poly (3,4-didodecyloxythiophene) 3,4-ethylenedioxythiophene), poly (3,4-propylenedioxythiophene), poly (3,4-butylenedioxythiophene), poly (3-methyl-4-methoxythiophene), poly (3- Methyl-4-ethoxythiophene), poly (3-carboxythiophene), poly (3-methyl-4-carboxythiophene), poly (3-methyl-4-carboxyethylthiophene), poly (3-methyl-4-carboxyphene) Butylthiophene).
Polypyrrole-based conductive polymers include polypyrrole, poly (N-methylpyrrole), poly (3-methylpyrrole), poly (3-ethylpyrrole), poly (3-n-propylpyrrole), and poly (3-butyl). Pyrrole), poly (3-octylpyrrole), poly (3-decylpyrrole), poly (3-dodecylpyrrole), poly (3,4-dimethylpyrrole), poly (3,4-dibutylpyrrole), poly (3) -Carboxypyrrole), poly (3-methyl-4-carboxypyrrole), poly (3-methyl-4-carboxyethylpyrrole), poly (3-methyl-4-carboxybutylpyrrole), poly (3-hydroxypyrrole) , Poly (3-methoxypyrrole), poly (3-ethoxypyrrole), poly (3-butoxypyrrole), poly (3-hexyloxypyrrole), poly (3-methyl-4-hexyloxypyrrole).
Examples of the polyaniline-based conductive polymer include polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), poly (2-aniline sulfonic acid), and poly (3-aniline sulfonic acid).
Among the π-conjugated conductive polymers, poly (3,4-ethylenedioxythiophene) is particularly preferable from the viewpoint of conductivity, transparency and heat resistance.
The π-conjugated conductive polymer contained in the conductive complex may be of one type or two or more types.

[Polyanion]
The polyanion is a polymer having two or more monomer units having an anion group in the molecule. The anionic group of this polyanion functions as a dopant for the π-conjugated conductive polymer and improves the conductivity of the π-conjugated conductive polymer.
The anion group of the polyanion is preferably a sulfo group or a carboxy group.
Specific examples of such polyanions include polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylsulfonic acid, poly (2-acrylamide-2-methylpropanesulfonic acid), and polyisoprene sulfonic acid. Polymers having a sulfonic acid group such as acid, polysulfoethyl methacrylate, poly (4-sulfobutyl methacrylate), polymethacryloxybenzene sulfonic acid, polyvinylcarboxylic acid, polystyrene carboxylic acid, polyallylcarboxylic acid, polyacrylic carboxylic acid. , Polymethacrylcarboxylic acid, poly (2-acrylamide-2-methylpropanecarboxylic acid), polyisoprenecarboxylic acid, polyacrylic acid and other polymers with carboxylic acid groups. These homopolymers may be used, or two or more kinds of copolymers may be used.
Among these polyanions, a polymer having a sulfonic acid group is preferable, and polystyrene sulfonic acid is more preferable, because the conductivity can be made higher.
The polyanion may be used alone or in combination of two or more.
The mass average molecular weight of the polyanion is preferably 20,000 or more and 1 million or less, and more preferably 100,000 or more and 500,000 or less. The mass average molecular weight of the polyanion is a mass-based molecular weight obtained by measuring the elution time using gel permeation chromatography (GPC) and obtaining it based on a calibration curve of elution time vs. molecular weight obtained in advance from a polystyrene standard substance having a known molecular weight. That is.

The content ratio of the polyanion in the conductive composite is preferably in the range of 1 part by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the π-conjugated conductive polymer, and is 10 parts by mass or more and 700 parts by mass or less. It is more preferable that the amount is 100 parts by mass or more and 500 parts by mass or less. When the content ratio of the polyanion is at least the above lower limit value, the doping effect on the π-conjugated conductive polymer tends to be strong, and the conductivity becomes higher. On the other hand, when the content of the polyanion is not more than the upper limit value, the π-conjugated conductive polymer can be sufficiently contained, so that sufficient conductivity can be ensured.

The content of the conductive composite in the conductive particles is preferably 0.1 part by mass or more and 100 parts by mass or less, and preferably 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the base particles. More preferably, it is 3 parts by mass or more and 10 parts by mass or less. When the content of the conductive complex in the conductive particles is not less than the lower limit value, the conductive particles can exhibit sufficient conductivity, and when the content is not more than the upper limit value, the conductive particles can be easily produced.

(Base particle)
The base particles constituting the conductive particles of this embodiment are not particularly limited, and are, for example, at least one of inorganic compound particles and polymer particles.
Examples of the inorganic compound particles include calcium carbonate, glass, silica, calcium hydroxide, talc, alumina, silica-alumina, titania, zirconia, magnesium hydroxide, aluminum hydroxide, hydrotalcite, mica and the like.
Examples of the polymer particles include acrylic resin particles, polyamide resin particles, polyurethane particles, polystyrene particles, polyester particles and the like.
The base particles may be used alone or in combination of two or more.
The base material particles are preferably particles containing one or more selected from the group consisting of calcium carbonate, glass, silica, calcium hydroxide, acrylic resin, and polyamide. When the base particle contains one or more selected from the group consisting of calcium carbonate, glass, silica, calcium hydroxide, acrylic resin, and polyamide, the mechanical properties of the resin containing the conductive particles are facilitated. Can be improved.

The median diameter of the base particles is preferably 0.01 μm or more and 100 μm or less, more preferably 0.1 μm or more and 50 μm or less, and further preferably 0.1 μm or more and 30 μm or less. When the median diameter of the base particles is not less than the lower limit value, the conductive particles can more effectively function as a filler, and when it is not more than the upper limit value, the conductive particles can be easily mixed with the resin.
The median diameter of the base particle is determined by using dynamic light scattering. The median diameter of the base particles is smaller than the median diameter of the conductive particles.

(Antioxidant)
The conductive particles of this embodiment may contain an antioxidant in order to prevent oxidative deterioration of the conductive particles.
Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, saccharides and the like. One type of antioxidant may be used alone, or two or more types may be used in combination.
Among the antioxidants, gallic acid (gallic acid) or gallic acid ester, which is a phenolic antioxidant, is preferable. Examples of the gallic acid ester include methyl gallicate, ethyl gallicate and the like. Galic acid and gallic acid ester have the effect of exhibiting high antioxidant performance and improving conductivity.

The content of the antioxidant in the conductive particles is preferably 0.1 part by mass or more and 1000 parts by mass or less, and more preferably 1 part by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the base particles. It is preferably 5 parts by mass or more and 100 parts by mass or less. If the content of the antioxidant in the conductive particles is at least the lower limit value, the antioxidant property and conductivity can be further enhanced, and if it is at least the upper limit value, the amount of the conductive complex is relatively high. It is possible to suppress a decrease in conductivity due to the decrease.

(High conductivity agent)
The conductive particles of this embodiment may contain a highly conductive agent that improves the conductivity of the conductive complex. Here, the above-mentioned π-conjugated conductive polymer, polyanion, and base particle are not classified as high conductivity agents.
Highly conductive agents include saccharides, nitrogen-containing aromatic cyclic compounds, compounds having two or more hydroxy groups, compounds having one or more hydroxy groups and one or more carboxy groups, and compounds having amide groups. It is preferably at least one compound selected from the group consisting of a compound having an imide group, a lactam compound, and a compound having a glycidyl group.
Among the highly conductive agents, an organic solvent having a boiling point of 100 ° C. or higher at standard atmospheric pressure is more preferable because it is easy to produce conductive particles containing the highly conductive agent. Among organic solvents having a boiling point of 100 ° C. or higher at standard atmospheric pressure, propylene glycol is preferable because it has an excellent effect of improving conductivity and is easy to handle.
One type of high conductivity agent may be used alone, or two or more types may be used in combination.

The content of the highly conductive agent is preferably 1 part by mass or more and 10000 parts by mass or less, more preferably 10 parts by mass or more and 5000 parts by mass or less, and 100 parts by mass with respect to 100 parts by mass of the conductive composite. It is more preferable that the amount is 2,500 parts by mass or less. When the content of the high conductive agent is at least the above lower limit value, the effect of improving the conductivity by adding the high conductivity agent is sufficiently exhibited, and when it is at least the above upper limit value, the concentration of the π-conjugated conductive polymer is lowered. It is possible to prevent a decrease in conductivity due to the above.

(Action effect)
Since the conductive particles of the present embodiment described above contain a conductive composite in addition to the base particles, they can sufficiently serve as a filler and also function as a conductivity-imparting agent.
In particular, the coated particles in which at least a part of the surface of the base particles is coated with the conductive composite has a high degree of exposure of the conductive composite, and has both a function as a filler and a function as a conductivity-imparting agent. Can be demonstrated more. Further, since the coated particles have a large amount of resin components on the surface and have high dispersibility in the resin when mixed with the resin, there is a tendency that the mechanical properties can be further improved while exhibiting conductivity. Therefore, the conductive particles containing the coated particles can more exert the effect of this embodiment.

<Manufacturing method of conductive particles>
The conductive particles of this embodiment can be produced, for example, by the following method for producing conductive particles according to the first embodiment or the method for producing conductive particles according to the second embodiment. According to the method for producing conductive particles of the first embodiment and the method for producing conductive particles of the second embodiment, the conductive particles of this embodiment can be easily produced. The conductive particles produced by the method for producing conductive particles of the second embodiment can impart higher conductivity when blended with a resin.

(First Embodiment)
In the method for producing conductive particles of the first embodiment, an aqueous dispersion of a conductive composite and raw material particles are mixed to prepare a mixed solution, and then water is removed to form a solid substance, and the solid substance is formed. Is a method for producing conductive particles.

The aqueous dispersion of the conductive composite is obtained by chemically oxidatively polymerizing a monomer forming a π-conjugated conductive polymer in an aqueous solution of a polyanion. Further, a commercially available aqueous dispersion of the conductive complex may be used.
A known catalyst may be applied to the chemical oxidative polymerization. For example, catalysts and oxidizing agents can be used. Examples of the catalyst include transition metal compounds such as ferric chloride, ferric sulfate, ferric nitrate and cupric chloride. Examples of the oxidizing agent include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. The oxidant can restore the reduced catalyst to its original oxidized state.
The content of the conductive composite contained in the aqueous dispersion of the conductive composite is preferably 0.1% by mass or more and 10% by mass or less with respect to the total mass of the water dispersion of the conductive composite, and is 0. .3% by mass or more and 5% by mass or less is more preferable, and 0.5% by mass or more and 4% by mass or less is further preferable.

The raw material particles are particles that become base particles after being pulverized. Therefore, the material of the raw material particles is the same as that of the base material particles, and is at least one of the inorganic compound particles and the polymer particles. Further, the raw material particles are preferably particles containing one or more selected from the group consisting of calcium carbonate, glass, silica, calcium hydroxide, acrylic resin, and polyamide.
The median diameter of the raw material particles is preferably 0.01 μm or more and 50 μm or less, more preferably 0.01 μm or more and 20 μm or less, and further preferably 0.01 μm or more and 10 μm or less. When the median diameter of the raw material particles is at least the above lower limit value, conductive particles having a size capable of sufficiently exerting the function as a filler can be easily produced. When the median diameter of the raw material particles is not more than the upper limit value, the crushing time at the time of crushing the solid matter described later can be shortened.
The median diameter of the raw material particles is 50% particle diameter D ₅₀ was determined by particle size measurement by dynamic light scattering method.

Examples of a method for preparing a mixed solution by mixing the aqueous dispersion of the conductive composite and the raw material particles include a method of adding the raw material particles to the aqueous dispersion of the conductive composite and an aqueous dispersion containing the raw material particles. Is mentioned, and the aqueous dispersion of the conductive complex is added to the aqueous dispersion. Water for diluting the mixed solution may be added to the aqueous dispersion of the conductive complex. When water is added and diluted, the conductive complex is easily attached to the surface of the raw material particles.
The mixture obtained by mixing the aqueous dispersion of the conductive composite and the raw material particles is a suspension containing the conductive composite, the raw material particles, and water.

When preparing the mixed solution, it is preferable to further mix the aqueous dispersion of the conductive composite and the raw material particles with an organic solvent having a boiling point of 100 ° C. or higher at standard atmospheric pressure (1013 hPa). When the mixed liquid is prepared, if an organic solvent having a boiling point of 100 ° C. or higher is further mixed, the effect of imparting conductivity to the conductive particles can be enhanced. An organic solvent having a boiling point of 100 ° C. or higher is less likely to volatilize during heat drying and tends to remain in the conductive particles.
The amount of the aqueous dispersion of the conductive complex and the organic solvent mixed with the raw material particles may be one type or two or more types.
Examples of organic solvents having a standard atmospheric pressure of 100 ° C. or higher include alcohol solvents, ether solvents, ketone solvents, ester solvents, aromatic hydrocarbon solvents, and the like, which have a standard atmospheric pressure boiling point of 100 ° C. or higher. Solvents can be mentioned. Among these organic solvents, an alcohol solvent having a boiling point of 100 ° C. or higher at standard atmospheric pressure is preferable because the effect of imparting conductivity to the conductive particles can be further improved.
Examples of alcohol-based solvents having a boiling point of 100 ° C. or higher include 1-butanol (boiling point 117 ° C.), 2-methyl-1-propanol (boiling point 108 ° C.), propylene glycol (boiling point 188 ° C.), and propylene glycol monomethyl ether. (Boiling point 120 ° C.), ethylene glycol monomethyl ether (boiling point 124 ° C.) and the like can be mentioned. The amount of the aqueous dispersion of the conductive complex and the alcohol-based solvent mixed with the raw material particles may be one type or two or more types.
Among the alcohol solvents, propylene glycol is more preferable because it has a particularly excellent effect of improving conductivity.

The amount of the organic solvent having a boiling point of 100 ° C. or higher is preferably 1 part by mass or more and 10000 parts by mass or less, and 10 parts by mass or more and 5000 parts by mass or less with respect to 100 parts by mass of the conductive composite. More preferably, it is 100 parts by mass or more and 2500 parts by mass or less. When the addition amount of the organic solvent having a boiling point of 100 ° C. or higher is not less than the lower limit value, the effect of improving the conductivity by adding the organic solvent is sufficiently exhibited, and when it is not more than the upper limit value, the concentration of the π-conjugated conductive polymer It is possible to prevent a decrease in conductivity due to a decrease in the conductivity.

In the method for producing conductive particles of this embodiment, the method for removing water from the mixed solution is not particularly limited, and examples thereof include heat drying, vacuum drying, and freeze drying. Of these dryings, it is preferable to remove the water by heat drying because the water can be quickly evaporated and removed.
When water is removed by heat drying, the heating temperature is preferably 50 ° C. or higher and 150 ° C. or lower, more preferably 70 ° C. or higher and 120 ° C. or lower, and further preferably 80 ° C. or higher and 110 ° C. or lower. If the heating temperature at the time of removing water is set to the lower limit value or more, water can be evaporated and removed more quickly, and if it is set to the upper limit value or less, thermal deterioration of the conductive complex can be suppressed.
The obtained solid matter contains raw material particles and a solid conductive composite. The shape of the solid conductive composite is not particularly fixed, and is, for example, a film-like shape, a lump-like shape, or the like. A part of the solid conductive composite is coated with raw material particles. There are also solid conductive complexes that are not coated with raw material particles.

By crushing the solid material, the raw material particles contained in the solid material and the solid conductive composite are made into fine particles. At that time, the raw material particles whose surface is coated with the conductive composite become the coated particles. Further, in addition to the coating particles, the crushed product obtained by crushing the solid material, that is, the conductive particles, includes, for example, conductive composite particles, base particles obtained by crushing raw material particles, and base particles and the conductive composite. Includes agglomerates or particles in which particles are integrated.
Examples of the method for crushing the solid matter obtained by removing water include a crushing method using a mortar and a crushing method using a mortar, and a crushing method using a crusher. As the crusher, for example, a ball mill, a roller mill, a jet mill, a hammer mill or the like can be used.
It is preferable to pulverize the solid material to produce conductive particles having a median diameter within the above-mentioned preferable range.

(Second Embodiment)
In the method for producing conductive particles of the second embodiment, an aqueous dispersion of a conductive composite containing a π-conjugated conductive polymer and a polyanion and raw material particles are mixed to prepare a mixed solution, and then organic. This is a method for producing conductive particles, in which a conductive composite is precipitated by adding a solvent to form a solid substance, and the solid substance is recovered.
The method for preparing the aqueous dispersion of the conductive complex and the method for preparing the mixed solution of the conductive complex and the raw material particles are the same as those in the first embodiment.

In a mixed solution containing the conductive complex and raw material particles, an organic solvent is added when the conductive complex is precipitated. Since the conductive composite is hydrated by the anion group of the polyanion, it is stably dispersed in water. However, when an organic solvent is added to the aqueous dispersion of the conductive composite, the hydration of the anion group of the polyanion decreases. To do. Therefore, the conductive complex cannot be stably dispersed in water and aggregates and precipitates. At that time, at least a part of the conductive composite adheres to the surface of the raw material particles and precipitates. Therefore, particles coated with the conductive composite are formed on the surface of the raw material particles.
As the organic solvent added to precipitate the conductive complex, a water-soluble organic solvent having a hydrophilic group is preferable because the conductive complex is more easily precipitated. Examples of the hydrophilic group include a hydroxy group, an amino group, a carbonyl group, a carboxy group and the like.
Among the water-soluble organic solvents having a hydrophilic group, a water-soluble organic solvent having a hydroxy group, that is, a water-soluble alcohol-based solvent is preferable, and isopropanol is more preferable, because it is easy to handle.

The amount of the organic solvent added to the mixed solution containing the conductive composite and the raw material particles is preferably 50 parts by mass or more and 1000 parts by mass or less, preferably 50 parts by mass or more, with respect to 100 parts by mass of the conductive composite mixed solution. It is more preferably 500 parts by mass or less, and further preferably 100 parts by mass or more and 200 parts by mass or less. When the amount of the organic solvent added is not less than the lower limit value, the conductive complex can be easily precipitated, and when the amount is not more than the upper limit value, the amount of the organic solvent remaining after the solid matter is recovered can be reduced.

Examples of the method for recovering a solid substance from water and an organic solvent include filtration, decantation, and centrifugation. For simplicity, it is preferable to recover the solid matter by filtration.
When the recovered solid matter is in the form of particles, it may be used as it is as conductive particles.
When the solid matter is not in the form of particles or has a large particle size, it is preferable to pulverize the obtained solid matter. By pulverizing the solid material, conductive particles having a median diameter within the above-mentioned preferable range can be easily produced. The method for crushing the solid matter is the same as the method for crushing the solid matter in the first embodiment.
When the solid material is crushed, in addition to the coating particles, the obtained crushed material includes, for example, conductive composite particles, base particles obtained by crushing raw material particles, and agglomerates of base particles and conductive composite particles. Includes particles in which an object or particles are integrated.
When the solid material is not pulverized, the solid material includes, for example, conductive composite particles, raw material particles, particles in which the conductive composite particles and the raw material particles are integrated, and the like, in addition to the coated particles. When the solid material is not crushed, the raw material particles become the base particles as they are. The preferred median diameter of the raw material particles when the solid material is not pulverized is the same as the preferred median diameter of the base particles.

<Conductive resin composition>
One aspect of the conductive resin composition of the present invention contains the conductive particles and a binder resin.
Examples of the binder resin include silicone resin, epoxy resin, acrylic resin, polyester resin, polyurethane resin, polyolefin resin, urea resin, polyamide resin, polystyrene resin, ABS resin, polyvinyl chloride resin, polycarbonate resin, polyacetal resin, and polyphenylene oxide. Examples thereof include resins, oxetane resins, polyimide resins, melamine resins, phenol resins, vinyl acetate resins and the like.
Further, the binder resin may be rubber. Examples of the rubber include natural rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, ethylene-propylene rubber and the like.
One type of the binder resin may be used alone, or two or more types may be used in combination.
The binder resin preferably contains at least one selected from the group consisting of silicone resin, epoxy resin, acrylic resin, polyester resin, polyurethane resin, polyolefin resin, urea resin, polyamide resin, and polystyrene resin. The conductive resin composition containing the above-mentioned preferable binder resin and conductive particles is industrially useful.

The content of the conductive particles in the conductive resin composition is preferably 1 part by mass or more and 1000 parts by mass or less, and more preferably 2 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder resin. It is more preferable that the amount is 3 parts by mass or more and 100 parts by mass or less. When the content of the conductive particles in the conductive resin composition is at least the above lower limit value, the conductivity of the conductive resin composition becomes higher, and the conductive resin composition depends on the type of the substrate particles. Performance can be improved. When the content of the conductive particles in the conductive resin composition is not more than the above upper limit value, deterioration of the mechanical properties of the conductive resin composition can be prevented.

The conductive resin composition of this embodiment may contain an antioxidant in order to prevent oxidative deterioration of the conductive resin composition. When the conductive resin composition of this embodiment contains an antioxidant, the conductivity can be enhanced.
The antioxidant is the same as the antioxidant that may be contained in the conductive particles. Similar to the conductive particles, the antioxidant that may be contained in the conductive resin composition of this embodiment is preferably gallic acid (gallic acid) or gallic acid ester.

The content of the antioxidant in the conductive resin composition is preferably 0.1 part by mass or more and 100 parts by mass or less, and 0.1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferably, it is more preferably 0.1 part by mass or more and 25 parts by mass or less. When the content of the antioxidant in the conductive resin composition is at least the above lower limit value, the antioxidant property and conductivity can be further enhanced, and when it is at least the above upper limit value, the mechanical resin composition is mechanical. It is possible to prevent deterioration of physical properties.

The conductive resin composition may contain other known additives.
The additive is not particularly limited as long as the effect of the present invention can be obtained, and for example, a surfactant, an inorganic conductive agent, a defoaming agent, a coupling agent, an ultraviolet absorber and the like can be used. However, the additive is a compound other than the above-mentioned conductive particles, binder resin and antioxidant.
Examples of the surfactant include nonionic, anionic and cationic surfactants, and nonionic surfactants are preferable from the viewpoint of storage stability. Further, a polymer-based surfactant such as polyvinylpyrrolidone may be added.
Examples of the defoaming agent include silicone resin, polydimethylsiloxane, silicone oil and the like.
Examples of the coupling agent include a silane coupling agent having an epoxy group, a vinyl group or an amino group.
Examples of UV absorbers include benzotriazole-based UV absorbers, benzophenone-based UV absorbers, salicylate-based UV absorbers, cyanoacrylate-based UV absorbers, oxanilide-based UV absorbers, hindered amine-based UV absorbers, benzoate-based UV absorbers, etc. Can be mentioned.
When the conductive resin composition contains the above additive, the content ratio thereof is appropriately determined according to the type of the additive. For example, 0.001 part by mass or more and 5 mass by mass with respect to 100 parts by mass of the binder resin. It can be in the range of less than a part.

As an example of the method for producing the conductive resin composition of this embodiment, there is a method of mixing conductive particles with the binder resin. The binder resin and the conductive particles may be mixed by simple stirring, or the binder resin and the conductive particles may be melt-kneaded by using a melt-kneader. Examples of the melt kneader include a single-screw extruder, a twin-screw extruder, a kneader, and a Banbury mixer. The heating temperature for melt-kneading may be appropriately determined according to the glass transition point or melting point of the binder resin to be used.
As another example of the method for producing the conductive resin composition of this embodiment, there is a method of mixing conductive particles with a monomer or oligomer forming a binder resin and polymerizing the monomer or the oligomer. For example, a conductive resin composition can be obtained by mixing conductive particles with curable silicone and polymerizing the curable silicone. Since the monomer or oligomer has a low viscosity, the conductive particles can be dispersed with high dispersibility without applying a high shearing force at the time of mixing.

By molding the conductive resin composition of this embodiment, a molded product can be manufactured. The molding method at the time of molding is not particularly limited. The conductive resin composition of this embodiment can be made into a molded product having an arbitrary shape by a known molding method such as an injection molding method, an extrusion molding method, a press molding method, a vacuum forming method, or a casting molding method.
The molded product of the conductive resin composition of this embodiment is used for a part that requires conductivity.

Conventionally, metal particles or carbon have been used as a conductivity-imparting agent for imparting conductivity to a resin, but a conductive resin composition containing metal particles or carbon may have reduced mechanical properties. Further, since the conductive resin composition containing carbon becomes black, there is a limitation in coloring and the design property is low.
On the other hand, in the conductive resin composition of this embodiment, the conductive particles sufficiently exert a function as a filler. Therefore, the performance of the conductive resin composition can be improved depending on the type of filler. For example, the mechanical properties, heat resistance, durability, abrasion resistance, etc. of the conductive resin composition can be improved.
In addition, the conductive resin composition of this embodiment can sufficiently exhibit conductivity due to the conductive particles.
Therefore, according to the conductive resin composition of this embodiment, it is possible to improve the performance of parts that require conductivity.
Further, since the conductive composite is a material having a slightly gray color, the conductive particles of this embodiment do not become black particles such as carbon. Therefore, the conductive resin composition of this embodiment can be colored in any color, and the design of the molded product obtained by molding the conductive resin composition can be enhanced.

Further, in the conductive resin composition of the present embodiment, when the conductive particles contain the coating particles, the effect of the present embodiment can be more exerted for the following reasons.
The coated particles tend to have high dispersibility in the binder resin. If the dispersibility of the conductive particles contained in the binder resin is high, the mechanical properties of the conductive resin composition can be further improved. Also, from the viewpoint of conductivity, if the dispersibility of the conductive particles is high, the conductivity can be further improved. Therefore, when the conductive particles contained in the conductive resin composition of this embodiment contain coated particles, the effect of this embodiment can be more exerted.

Since the π-conjugated conductive polymer is obtained as a conductive polymer dispersion, conventionally, a paint, for example, a paint for forming a conductive layer constituting a conductive film, and a solid electrolyte constituting a solid electrolytic capacitor are formed. It was used as a paint, etc.
In this embodiment, the π-conjugated conductive polymer is made into particles and contained in a resin composition for producing a molded product. Therefore, according to this aspect, the use of the π-conjugated conductive polymer can be expanded.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following Examples.

(Production Example 1) Production of polystyrene sulfonic acid 1.14 g of ammonium persulfate oxidant solution dissolved in 10 ml of water in advance by dissolving 206 g of sodium styrene sulfonate in 1000 ml of ion-exchanged water and stirring at 80 ° C. Was added dropwise for 20 minutes, and the solution was stirred for 12 hours. To the obtained sodium styrene sulfonate-containing solution, 1000 ml of sulfuric acid diluted to 10% by mass was added, 1000 ml of the polystyrene sulfonate-containing solution was removed using an ultrafiltration method, and 2000 ml of ion-exchanged water was added to the residual liquid. Was added, and about 2000 ml of the solution was removed using an ultrafiltration method. The above ultrafiltration operation was repeated 3 times. Further, about 2000 ml of ion-exchanged water was added to the obtained polystyrene sulfonic acid solution, and about 2000 ml of the solution was removed by using an ultrafiltration method. This ultrafiltration operation was repeated 3 times. Water in the obtained solution was removed under reduced pressure to obtain a colorless solid. The mass average molecular weight of the obtained polystyrene sulfonic acid was measured using an HPLC (High Performance Liquid Chromatography) system using a GPC (Gel Permeation Chromatography) column using Plulan manufactured by Showa Denko Co., Ltd. as a standard substance. It was 300,000.

(Production Example 2) Production of PEDOT-PSS aqueous dispersion A solution of 14.2 g of 3,4-ethylenedioxythiophene and 36.7 g of polystyrene sulfonic acid obtained in Production Example 1 in 2000 ml of ion-exchanged water. And were mixed at 20 ° C. While keeping the mixed solution thus obtained at 20 ° C. and stirring, 29.64 g of ammonium persulfate dissolved in 200 ml of ion-exchanged water and 8.0 g of a ferric sulfate oxidation catalyst solution were slowly added. The reaction was carried out with stirring for 3 hours. 2000 ml of ion-exchanged water was added to the obtained reaction solution, and about 2000 ml of the solution was removed using an ultrafiltration method. This operation was repeated 3 times. Next, 200 ml of sulfuric acid diluted to 10% by mass and 2000 ml of ion-exchanged water were added to the obtained solution, and about 2000 ml of the solution was removed using an ultrafiltration method, to which 2000 ml of ion-exchanged water was removed. Was added, and about 2000 ml of the solution was removed using an ultrafiltration method. This operation was repeated 3 times. Further, 2000 ml of ion-exchanged water was added to the obtained solution, and about 2000 ml of the solution was removed by using an ultrafiltration method. This operation was repeated 5 times to obtain a blue PEDOT-PSS aqueous dispersion having a solid content concentration of 1.2% by mass and PEDOT: PSS = 1: 2.5 (mass ratio).

(Example 1)
100 g of water was added to 30 g of the PEDOT-PSS aqueous dispersion obtained in Production Example 2 (3.6 parts by mass of PEDOT-PSS solid content with respect to 100 parts by mass of calcium carbonate described later), and calcium carbonate (D ₁₀ : 0) was added. .04 μm, D ₅₀ : 7.73 μm, D ₉₀ : 12.01 μm) 10 g was added. The resulting mixture was heated to 100 ° C. and dried until all the liquid had evaporated to give a solid. The obtained solid matter was ground using a mortar and pestle and pulverized to obtain conductive particles.

(Example 2)
Conductive particles were obtained in the same manner as in Example 1 except that the amount of the PEDOT-PSS aqueous dispersion was changed to 50 g.

(Example 3)
Conductive particles were obtained in the same manner as in Example 1 except that the amount of the PEDOT-PSS aqueous dispersion was changed to 70 g.

(Example 4)
Conductive particles were obtained in the same manner as in Example 1 except that 5 g of propylene glycol was added to 30 g of the PEDOT-PSS aqueous dispersion in addition to 100 g of water and 10 g of calcium carbonate.

(Example 5)
Conductive particles were obtained in the same manner as in Example 2 except that 5 g of propylene glycol was added to 50 g of the PEDOT-PSS aqueous dispersion in addition to 100 g of water and 10 g of calcium carbonate.

(Example 6)
Conductive particles were obtained in the same manner as in Example 3 except that 5 g of propylene glycol was added to 70 g of the PEDOT-PSS aqueous dispersion in addition to 100 g of water and 10 g of calcium carbonate.

(Example 7)
To 30 g of the PEDOT-PSS aqueous dispersion obtained in Production Example 2, 100 g of water was added, and 10 g of calcium carbonate and 100 g of isopropanol were added. With the addition of isopropanol, PEDOT-PSS was precipitated on the surface of calcium carbonate. The resulting mixture was filtered to give a powder. The powder was suction dried at room temperature for 24 hours. The solid material obtained by drying was ground using a mortar and pestle and pulverized to obtain conductive particles.

<Evaluation>
10 g of conductive particles of each example and 10 g of additive-curable silicone (KNS-320A, manufactured by Shin-Etsu Chemical Co., Ltd., 100% by mass of non-volatile content) are mixed, and a platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., CAT-PL) is further mixed. -50T) 0.2g was added. The obtained mixture was cured by heating at 150 ° C. for 5 minutes to obtain a conductive resin composition.
A dispersion liquid in which 1 g of the conductive resin composition was dispersed in 100 g of water was prepared, and the particle size distribution of the particles contained in the dispersion liquid was measured using a dynamic light scattering particle size distribution measuring device (FPAR1000, manufactured by Otsuka Electronics Co., Ltd.). Was measured. _{The results of D 10} , D ₅₀ and D ₉₀ obtained by the measurement are shown in Table 1.
Further, the surface resistance value of the obtained conductive resin composition was measured using a resistivity meter (High Resta manufactured by Mitsubishi Chemical Analytical Co., Ltd.) under the condition of an applied voltage of 10 V. The measurement results are shown in Table 1.

The conductive resin composition containing the conductive particles of each example had high conductivity. Among the examples, the conductive resin composition containing the conductive particles of Examples 4 to 6 to which propylene glycol was added had higher conductivity.
The conductive particles of Example 7 obtained by precipitating PEDOT-PSS by adding isopropanol have a more conductive resin composition than the conductive particles of Example 1 obtained by solidifying PEDOT-PSS by heating and drying. The effect of improving the conductivity of the object was high.

Claims (4)

A mixed solution is prepared by mixing an aqueous dispersion of a conductive complex containing a π-conjugated conductive polymer and a polyanion with raw material particles, and then an organic solvent is added to precipitate the conductive complex. A method for producing conductive particles, wherein a solid material containing the conductive composite and the raw material particles is formed, and the solid material is recovered. The method for producing conductive particles according to claim 1, wherein the solid matter is pulverized. The method for producing conductive particles according to claim 1 or 2, wherein the organic solvent is an alcohol solvent. The method for producing conductive particles according to claim 3, wherein the alcohol solvent is isopropanol.