JP2024029650A - Conductive particle dispersion method and electrostatic adsorption device - Google Patents

Abstract

An object of the present invention is to provide a method for dispersing conductive particles, which can two-dimensionally arrange conductive particles at a distance on a base material, and can improve the efficiency of dispersing the conductive particles. [Solution] A method for dispersing conductive particles includes: a first electrode 4 having a placement part 2 having electrostatic dissipative or conductive properties in which particles are placed; and a second electrode having an adsorption part 5 facing the placement part 2. By forming an electric field between the arrangement part 2 and the adsorption part 5, the blended particles P, in which conductive particles having a particle size smaller than that of the intermediary particles are attached to the intermediary particles arranged in the arrangement part 2, are transferred between the arrangement part 2 and the adsorption part 5. The arrangement part 2 has a recess 30 that opens toward the adsorption part 5, and the recess 30 has a recess 30 that opens toward the adsorption part 5. It has an inner wall surface S1 that is tapered so that the opening width increases, and the blended particles P are arranged in the recess 30. [Selection diagram] Figure 1

Description

The present invention relates to a method for dispersing conductive particles and an electrostatic adsorption device.

Methods for arranging particles two-dimensionally on a substrate include the dip coating method, in which the substrate is immersed in a dispersion liquid containing spherical particles, the substrate is pulled up, and the dispersion medium is dried and removed, and the advection accumulation method. methods are known (for example, see Patent Document 1 below). These methods utilize the self-assembly phenomenon of particles, and are techniques suitable for arranging particles in a close-packed arrangement or forming a particle film.

On the other hand, the present inventors have been developing a technology for two-dimensionally arranging conductive particles at a distance on a base material. A technique has been proposed in which conductive particles are dispersed and arranged in an adsorption part using blended particles to which conductive particles are attached (see, for example, Patent Document 2 below).

Japanese Patent Application Publication No. 2009-223154 Japanese Patent Application Publication No. 2021-074707

The method for dispersing conductive particles described in Patent Document 2 above uses electrostatic repulsion between conductive particles and disperses the conductive particles in a dry process, which causes little damage to the conductive particles and does not require a dispersion solvent. It has the following advantages. This method could become a more useful technique if the efficiency of dispersion of conductive particles is improved.

Therefore, the present invention provides a method for dispersing conductive particles that can two-dimensionally arrange conductive particles at a distance on a base material, and that can improve the efficiency of dispersion of conductive particles, and a method for use in the method. The purpose of the present invention is to provide an electrostatic adsorption device that can.

One aspect of the present invention is to form an electric field between a first electrode having a dissipating portion having static electricity dissipation or conductivity, and a second electrode having an adsorption portion facing the dispersing portion. A process of adsorbing the conductive particles to the adsorption part by reciprocating the blended particles arranged in the part, in which conductive particles having a particle size smaller than that of the intermediary particles are attached, between the arrangement part and the adsorption part. , the placement part has a recess that opens toward the suction part, the recess has an inner wall surface that is tapered such that the opening width increases toward the suction part, and the blended particles are placed in the recess. A method for dispersing conductive particles is provided.

According to the above method, the conductive particles can be arranged two-dimensionally on the base material at a distance, and the efficiency of dispersion of the conductive particles can be improved.

The particle size of the mediating particles may be 10 to 100 times the particle size of the conductive particles. In this case, it becomes easier to move the blended particles while suppressing aggregation of the blended particles.

The particle size of the conductive particles may be 2 to 50 μm.

The adsorption section may have an opening pattern that opens toward the arrangement section.

Another aspect of the present invention includes a first electrode having an arrangement section having static electricity dissipation property or conductivity, and a second electrode having an adsorption section, the arrangement section and the adsorption section facing each other. An electrostatic adsorption device is provided, in which the arrangement part has a recess opening toward the adsorption part, and the recess has an inner wall surface tapered such that the opening width increases toward the adsorption part. provide.

Such an electrostatic adsorption device can be used as a dispersion device for conductive particles by using blended particles in which conductive particles smaller in particle size than the mediator particles are attached to the mediator particles.

According to the present invention, a method for dispersing conductive particles that can two-dimensionally arrange conductive particles at a distance on a base material, and that can improve the efficiency of dispersion of conductive particles, and a method for use in the method. It is possible to provide an electrostatic adsorption device that can.

1 is a diagram showing a schematic configuration of an electrostatic adsorption device used in a method for dispersing conductive particles according to an embodiment of the present invention. (a-1) to (d-1) in FIG. 2 are plan views schematically showing examples of arrangement parts, and (a-2) to (d-2) in FIG. -1) to (d-1) are cross-sectional views along line II to IV-IV, and (a-3) to (d-3) in FIG. 2 are cross-sectional views showing other cross-sectional shapes of the arrangement part. It is a diagram. (e-1) to (f-1) in FIG. 3 are plan views schematically showing examples of arrangement parts, and (e-2) to (f-2) in FIG. -1) to (f-1) are cross-sectional views along the VV line to VI-VI line, and (e-3) to (f-3) in FIG. 3 are cross-sectional views showing other cross-sectional shapes of the arrangement part. It is a diagram. (g-1) to (j-1) in FIG. 4 are plan views schematically showing examples of arrangement parts, and (g-2) to (j-2) in FIG. -1) to (j-1) along VII-VII line to XX line, and (g-3) to (j-3) in FIG. 4 are cross-sectional views showing other cross-sectional shapes of the arrangement part. It is a diagram. FIG. 2 is a schematic diagram showing blended particles used in a method for dispersing conductive particles according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining a method for dispersing conductive particles according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining an example of an electrostatic adsorption device. FIG. 2 is a schematic diagram for explaining a method of dispersing conductive particles in Examples and Reference Examples.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail, with reference to the drawings as the case may be. However, the present invention is not limited to the following embodiments.

Note that in the numerical ranges described in stages in this specification, the upper limit or lower limit of the numerical range of one stage may be replaced with the upper limit or lower limit of the numerical range of another stage. Furthermore, in the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with the values shown in the examples. Furthermore, in this specification, for convenience, a collection of a plurality of conductive particles is also referred to as a "conductive particle." The same applies to mediating particles and compounding particles.

[Dispersion method of conductive particles]
The method for dispersing conductive particles according to the present embodiment includes forming an electric field between a first electrode having an arrangement part having static dissipative properties or conductivity, and a second electrode having an adsorption part facing the arrangement part. By doing this, the blended particles arranged in the arrangement section, in which conductive particles smaller in particle size than the intermediary particles are attached, are reciprocated between the arrangement section and the adsorption section, and the conductive particles are transferred to the adsorption section. and a step of adsorbing it to. In this step, the placement part has a recess that opens toward the suction part, and the recess has an inner wall surface that is tapered so that the opening width increases toward the suction part. Particles are placed.

According to the above method, when the adsorption part has electrostatic dissipation property or conductivity, the second electrode is generated by the reciprocating movement of the compounded particles, that is, the electrostatic attraction generated when the compounded particles are charged with the opposite polarity to the second electrode. By repeating the movement to the electrode and the movement to the first electrode due to the electrostatic repulsion generated when the blended particles in contact with the adsorption part are charged to the same polarity as the second electrode, the medium particles with a large particle size are Conductive particles with a small particle size adhering to the surface can be adsorbed to the adsorption part. Further, according to the above method, since the arrangement section has the above-mentioned recess, the adhesion density of the conductive particles adsorbed to the adsorption section can be increased, and the efficiency of dispersion and arrangement of the conductive particles can be increased. . In addition, the present inventors speculate as follows about the reason why the adhesion density of conductive particles becomes high. It is thought that because the arrangement part of the first electrode has a recess with the above-mentioned inner wall surface, the equipotential surface becomes a concavely curved equipotential distribution near the recess, making it easier for electrostatic force to gather at the center of the recess. It will be done. This is thought to have resulted in the above effect being achieved by suppressing the scattering of the blended particles outside the recess during vertical movement and increasing the number of blended particles that can be reciprocated per unit time and unit area. It will be done.

In addition, when the adsorption part has insulating properties, the adsorption part is placed above the arrangement part in the direction of gravity, which causes the reciprocating movement of the compounded particles, that is, the compounded particles are charged with a polarity opposite to that of the second electrode. The particle size decreases by repeating the process of movement to the second electrode due to the electrostatic attraction generated by the electrostatic attraction, and then the compound particles that have contacted the adsorption part release the conductive particles, which removes the charge, and then move to the first electrode due to their own weight. The conductive particles with a small particle size attached to the surface of the large medium particle can be adsorbed to the adsorption part.

The above method includes a first electrode having an arrangement part having static dissipative properties or conductivity, and a second electrode having an adsorption part, in which the arrangement part and the adsorption part can face each other, and the arrangement part A step of preparing an electrostatic adsorption device having the above-mentioned concave portion that opens toward the adsorption portion, and arranging blended particles in which conductive particles having a particle size smaller than that of the intermediary particles are attached to the intermediary particles in the recess of the arrangement portion ( (hereinafter also referred to as the first step), an electric field is formed between the first electrode and the second electrode, and the blended particles are reciprocated between the placement section and the adsorption section to transfer the conductive particles to the adsorption section. (hereinafter also referred to as the second step).

The electrostatic dissipative arrangement portion and the electrostatic dissipative adsorption portion may each have a surface resistivity of 1×10 ¹³ Ω or less, or 1×10 ⁶ Ω or more. The conductive arrangement portion and the conductive suction portion may each have a surface resistivity of 1×10 ⁶ Ω or less, or 1×10 ⁻³ Ω or more.

FIG. 1 is a diagram showing a schematic configuration of an electrostatic adsorption device used in the method for dispersing conductive particles according to the present embodiment. The electrostatic adsorption device 1 includes a lower electrode (first electrode) 4 having an arrangement section 2 for disposing particles, and an adsorption section 5 that is disposed above the arrangement section 2 in the direction of gravity and faces the arrangement section 2. A power supply 8 is connected to the lower electrode 4 and the upper electrode 7, and a control unit 9 is connected to the power supply 8.

In the electrostatic adsorption device 1, the lower electrode 4 is composed of an electrode main body 3 and a placement section 2, and the upper electrode 7 is composed of an electrode main body 6 and an adsorption section 5. In the lower electrode, the electrode main body and the placement part may be integrated, and in the case where the adsorption part has static dissipation properties or conductivity, the upper electrode may have the electrode main body and the adsorption part integrated. In these cases, the surface of the lower electrode facing the upper electrode can be used as the arrangement part, and the surface of the upper electrode facing the lower electrode can be used as the adsorption part.

As the material of the electrode body 3 constituting the lower electrode 4, a material having static dissipation properties or conductivity can be used. For example, a material having a surface resistivity of 1×10 ¹³ Ω or less can be used, and specific examples thereof include metal, glass, and the like. The shape of the electrode main body 3 is not particularly limited, but may be, for example, flat or rolled.

As the material for the arrangement portion 2, a material having static electricity dissipation properties or conductivity can be used. For example, a material having a surface resistivity of 1×10 ¹³ Ω or less can be used, and specific examples thereof include metal, glass, and conductive resin such as conductive polytetrafluoroethylene (PTFE). The shape of the arrangement section 2 is not particularly limited as long as particles can be arranged therein, and it may be a membrane or a film formed on the surface of the electrode body 3.

The arrangement section 2 is provided with a recess 30 that opens toward the suction section 5 side. The recess 30 has an inner wall surface S ₁ that is tapered such that the opening width increases toward the suction portion 5 . The placement portion shown in FIG. 1 has a flat portion _S0 and a hemispherical recess 30, and the blended particles P can be placed in the recess 30. The recesses may have other shapes, may be provided in plurality, or may be provided in a predetermined pattern.

The shape of the recess may be, for example, a hemispherical shape, an inverted conical shape, an inverted truncated conical shape, an inverted polygonal shape such as an inverted triangular pyramid shape or a reversed square shape, an inverted polygonal truncated shape such as an inverted square truncated shape, or a transverse shape. The surface may be V-shaped, U-shaped, or valley-shaped such as an inverted trapezoid. In addition, when a recessed part is valley-shaped, the opening width of a recessed part means the width of a valley.

The inner wall surface of the recess may be tapered such that the opening area increases from the bottom of the recess toward the suction portion.

The tapered inner wall surface may be part or all of the inner wall of the recess. The recess may have a wall surface in which the opening width does not increase.

The tapered inner wall surface may have a stepped shape or may have roughness.

2 to 4 are diagrams showing examples of arrangement portions provided with recesses. The arrangement portion 2a shown in (a-1) to (a-3) of FIG. 2 is provided with a hemispherical recess 30a. As shown in FIG. 2(a-3), the side surface of the arrangement portion 2a opposite to the side on which the recess is provided may be flat. The arrangement portion 2b shown in (b-1) to (b-3) of FIG. 2 is provided with a concave portion 30b in the shape of an inverted truncated cone having a flat bottom surface _S2 . As shown in FIG. 2B-3, the side surface of the arrangement portion 2b opposite to the side on which the recess is provided may be flat. The arrangement portion 2c shown in (c-1) to (c-3) of FIG. 2 is provided with an inverted quadrangular pyramid-shaped recess 30c. As shown in (c-3) of FIG. 2, the side surface of the arrangement portion 2c opposite to the side on which the recess is provided may be flat. The arrangement portion 2d shown in (d-1) to (d-3) of FIG. 2 is provided with a concave portion 30d in the shape of an inverted quadrangular truncated pyramid having a flat bottom surface _S2 . As shown in (d-3) of FIG. 2, the side surface of the placement portion 2d opposite to the side where the recess is provided may be flat.

The arrangement portion 2e shown in (e-1) to (e-3) of FIG. 3 is provided with a U-shaped valley-shaped recess 30e extending in one direction. As shown in FIG. 3(e-3), the side surface of the arrangement portion 2e opposite to the side on which the recess is provided may be flat. The arrangement portion 2f shown in (f-1) to (f-3) in FIG. 3 is provided with a V-shaped valley-shaped recess 30f extending in one direction. As shown in (f-3) of FIG. 3, the side surface of the placement portion 2f opposite to the side on which the recess is provided may be flat.

In the arrangement portion 2g shown in (g-1) to (g-2) of FIG. 4, a plurality of inverted rectangular concave portions 30g are provided in a lattice pattern. The arrangement portion 2g has a flat portion between the recesses 30g. In the arrangement portion 2h shown in (h-1) to (h-2) in FIG. 4, a plurality of U-shaped valley-shaped recesses 30h are arranged side by side. The arrangement portion 2h has a flat portion between the recesses 30h. In the arrangement portion 2i shown in (i-1) to (i-2) of FIG. 4, a plurality of inverted rectangular concave portions 30i are provided in a predetermined pattern. In the arrangement portion 2j shown in (j-1) to (j-2) in FIG. 4, a plurality of U-shaped valley-shaped recesses 30j are arranged side by side.

The size of the recess (width, opening area, volume, taper angle and depth of the inner wall surface, etc.) may be appropriately set depending on the amount of blended particles to be placed. For example, when the recess has a hemispherical shape, an inverted conical shape, or an inverted truncated conical shape, the maximum diameter of the opening may be 2 to 200 mm, and the maximum depth may be 0.1 to 100 mm, The maximum diameter/maximum depth may be 0.02 to 2000. When the recess has an inverted polygonal thrust shape or an inverted polygonal trapezoid shape, the maximum width of the opening may be 2 to 200 mm, the maximum depth may be 0.1 to 100 mm, and the maximum width/maximum depth The length may be 0.02 to 2000. When the recess is valley-shaped, the maximum width of the valley may be 2 to 200 mm, the maximum depth may be 0.1 to 100 mm, and the maximum width/maximum depth may be 0.02 to 2000. There may be.

As the lower electrode in which the electrode body and the arrangement portion are integrated, for example, one made of a material such as metal or glass having a surface resistivity of 1×10 ¹³ Ω or less can be used.

As the electrode body 6 constituting the upper electrode 7, one having static electricity dissipation properties or conductivity can be used. For example, a material having a surface resistivity of 1×10 ¹³ Ω or less can be used, and specific examples thereof include metal, glass, and the like. The shape of the electrode body 6 is not particularly limited, but may be, for example, flat, rolled, or the like. Note that when one of the electrode bodies 3 and 6 is in the form of a roll and the other is in the form of a flat plate, the rotation axis of the roll and the main surface of the flat plate are in a parallel relationship, and the rotation axis and the main surface are connected at the shortest possible distance. The electrodes 4 and 7 may be configured so that the suction part and the arrangement part face each other with a predetermined distance apart on the connecting line. In addition, when both the electrode body 3 and the electrode body 6 are roll-shaped, the rotation axes of both rolls are parallel to each other, and the adsorption part and the arrangement part are separated by a predetermined distance on the line connecting the rotation axes at the shortest distance. The electrodes 4 and 7 may be configured to face each other with a distance between them.

As the material of the adsorption part 5, a material having static electricity dissipation properties or conductivity can be used. For example, a material having a surface resistivity of 1×10 ¹³ Ω or less can be used, and specific examples thereof include metal, glass, and conductive resin such as conductive PTFE. The shape of the suction portion 5 is not particularly limited, and may be a membrane or a film formed on the surface of the electrode body 6.

As the upper electrode in which the electrode body and the suction part are integrated, for example, one made of a material such as metal or glass having a surface resistivity of 1×10 ¹³ Ω or less can be used.

As the material of the suction part 5, a material having insulating properties can also be used. For example, a material with a surface resistivity of more than 1×10 ¹³ Ω can be used. Examples include resins such as polytetrafluoroethylene. The shape of the adsorption portion 5 is not particularly limited, and may be a membrane or film formed on the surface of the electrode body 6, or may be a film that is separable from the electrode body.

The adsorption section 5 may be provided with an opening pattern (a plurality of openings (for example, recesses)) that opens toward the arrangement section. The shape of the suction portion 5 may be a membrane or film formed on the surface of the electrode body 6, or may be a film that is separable from the electrode body 6.

The opening is preferably formed in a tapered shape such that the opening area increases from the bottom side of the opening toward the arrangement section. The size of the opening (width, volume, taper angle, depth, etc.) may be set depending on the size of the conductive particles to be accommodated.

For example, the width of the opening can be 1.0 to 1.5 times, or 1.05 to 1.45 times, the particle size of the conductive particles. Further, the particle size of the mediating particles can be 2.0 to 110 times, or 2.5 to 100 times, the width of the opening.

The shape of the opening may be circular, oval, triangular, quadrilateral, polygonal, or the like. The bottom portion may have a shape other than a flat surface, for example, a mountain shape, a valley shape, an aggregate of fine protrusions, or the like.

As the material constituting the adsorption part 5 having static dissipative properties or conductivity, for example, inorganic materials such as silicon, various ceramics, glass, metals such as stainless steel, and organic materials such as various resins can be used. can. The opening of the suction part can be formed by a known method such as photolithography or nanoimprint. Further, the suction portion 5 may be a single layer, or may be composed of a plurality of layers such as a laminate of a base layer and an opening layer provided with openings. When the adsorption part 5 is a laminate, for example, it is a film comprising an opening layer formed on a base layer such as PET using a photocurable resin composition by a method such as photolithography or nanoimprinting. Good too. The static electricity dissipation property or conductivity of the adsorption part can be adjusted by the type of constituent material, surface treatment, etc.

As the material constituting the insulating suction part 5, for example, inorganic materials such as silicon and various ceramics, and organic materials such as various resins can be used. In addition, as the material constituting the insulating suction part 5, for example, a static dissipative or conductive material is laminated or coated with inorganic materials such as silicon, various ceramics, and organic materials such as various resins. It is also possible to use other materials. The opening of the suction part can be formed by a known method such as photolithography or nanoimprint. Further, the suction portion 5 may be a single layer, or may be composed of a plurality of layers such as a laminate of a base layer and an opening layer provided with openings. When the adsorption part 5 is a laminate, for example, it is a film comprising an opening layer formed on a base layer such as PET using a photocurable resin composition by a method such as photolithography or nanoimprinting. Good too.

The opening pattern can be appropriately set so that the conductive particles can be dispersed in a desired arrangement. For example, the openings of the round holes may be arranged in series in a grid pattern, or may be arranged in a 60° staggered pattern. Further, the opening pattern may be such that the openings are arranged in a row or randomly.

In the electrostatic adsorption device 1, the lower electrode 4 and the upper electrode 7 are arranged with a predetermined interval, and the distance between the electrodes can be 0.5 to 100 mm, or even 1 to 20 mm. It may be between 2 and 15 mm.

In the electrostatic adsorption device 1, the lower electrode 4 may be movable, and in this case, it becomes easy to continuously supply the blended particles. For example, a lower electrode can be provided on the surface of a belt or a cylindrical roller.

In the electrostatic adsorption device 1, the upper electrode 7 may be movable, and in this case, it becomes easy to continuously supply an adsorption part that adsorbs conductive particles. For example, an upper electrode can be provided on the surface of a belt or a cylindrical roller.

The power source 8 may be any power source that can form an electric field between the lower electrode and the upper electrode, and for example, a known high voltage power source can be used. The high voltage power supply may be a DC power supply or an AC power supply.

The control unit 9 can have functions such as adjusting the applied voltage and applying the voltage, for example.

<First step>
In the first step, blended particles in which conductive particles having a particle size smaller than the mediating particles are attached to the mediating particles are placed (accommodated) in the recess 30 of the placement section 2 of the electrostatic adsorption device 1 described above. FIG. 5 is a schematic diagram showing blended particles. As shown in FIG. 5, the blended particles P are composed of a mediating particle 10 and conductive particles 12 attached to the surface of the mediating particle.

The mediating particles 10 may be particles having electrostatic dissipative properties or conductivity, and particles containing a material having a surface resistivity of 1×10 ¹³ Ω or less can be used. For example, carbon particles, metal particles such as solder, glass particles, and inorganic particles having static dissipative properties can be used. These can be used alone or in combination of two or more.

The mediating particle 10 may be spherical or approximately spherical, and may have a concave portion, a convex portion, or a concave portion and a convex portion on the surface.

The particle size of the mediating particles 10 may be 30 to 500 μm, 40 to 400 μm, or 50 to 300 μm, from the viewpoint of suppressing agglomeration of the compound particles and making it easier to move the compound particles. Good too.

In this embodiment, mediating particles having an average particle size within the above range may be used. In this specification, the average particle diameter of particles is obtained by measuring the particle diameters of 100 particles by observation using a scanning electron microscope (SEM) and taking the average value. In addition, when a particle is not spherical, such as having a protrusion, the particle size of the particle is the diameter of a circle circumscribing the particle in an SEM image.

Further, when the mediating particles 10 are placed in the arrangement part of the electrostatic adsorption device where the second step is performed and an electric field is applied under predetermined conditions described below, the lower electrode (first electrode) and the upper electrode ( The selection may be made by a method of confirming reciprocating movement between the electrodes (second electrode).

The conductive particles 12 may be any material as long as it contains a conductive material and functions as a conductive material, such as metal particles such as gold, silver, nickel, copper, and solder, carbon particles, glass, ceramic, plastic, etc. Examples include conductive coated particles in which non-conductive particles are coated with a conductive substance such as metal. Examples of the metal that covers the non-conductive particles include gold, silver, nickel, copper, and solder, and may have a multilayer structure. Further, the conductive particles may have an insulating coating (for example, insulating fine particles) on at least a portion of the outer surface of the conductive particles.

The conductive particles can be used alone or in combination of two or more.

The conductive particles 12 may be spherical or approximately spherical, or may be composite particles including a conductive particle and a plurality of insulating fine particles provided on at least a portion of the outer surface of the conductive particle.

The particle size of the conductive particles 12 may be 1 to 50 μm, 2 to 50 μm, 1 to 40 μm, 1.5 to 30 μm, or 2 to 20 μm. There may be.

In this embodiment, conductive particles having an average particle size within the above range may be used.

The particle size of the mediating particles constituting the blended particles P may be 5 to 200 times the particle size of the conductive particles, or even 10 to 150 times, from the viewpoint of efficiently adsorbing the conductive particles to the adsorption part. It may be 10 to 100 times more.

Compounded particles P can be prepared by mixing mediating particles and conductive particles. The mixing method is not particularly limited, but for example, a known mixing means such as a stirrer may be used, or a container containing the mediator particles and conductive particles may be shaken. Mixing is preferably carried out within a range that does not damage the particles.

The mixing ratio of the mediating particles and the conductive particles can be appropriately set so that the conductive particles are sufficiently attached to the surfaces of the mediating particles. Note that if the blending amount of the conductive particles is too large, agglomeration of the conductive particles tends to occur, so it is preferable to set the blending ratio within a range that can suppress aggregation of the conductive particles.

<Second process>
In the second step, an electric field is formed between the first electrode and the second electrode to cause the blended particles to reciprocate between the placement section and the adsorption section, thereby adsorbing the conductive particles to the adsorption section.

FIG. 6 is a diagram for explaining the second step, and (a) in FIG. 6 shows the state when an electric field is applied between the lower electrode (first electrode) and the upper electrode (second electrode). It shows the reciprocating motion (up and down motion) of the blended particles. The blended particles, which are charged to the opposite polarity to the upper electrode at the placement part, rise due to electrostatic attraction. The blended particles that have risen come into contact with the adsorption section. At this time, the small-sized conductive particles adhering to the surface of the large-sized medium particles are attracted to the adsorption part. When the adsorption part has electrostatic dissipation properties or conductivity, the blended particles that come into contact with the adsorption part are charged to the same polarity as the upper electrode, and descend due to electrostatic repulsion and, in this embodiment, gravity. Further, when the adsorption part has insulating properties, the blended particles that have come into contact with the adsorption part are no longer charged as the conductive particles move to the adsorption part, and in this embodiment, they descend due to gravity. The blended particles that have descended are charged with the opposite polarity to that of the upper electrode at the placement part, and are lifted up by electrostatic attraction. By repeating these operations, the conductive particles are attracted to the adsorption part. Furthermore, by attaching the conductive particles to the surface of the mediating particles, it is possible to suppress the conductive particles from aggregating with each other, and the conductive particles adsorbed to the adsorption part are arranged at a distance from each other. Furthermore, in this embodiment, since the arrangement section has the above-mentioned recess, the adhesion density of the conductive particles adsorbed to the adsorption section can be increased, and the efficiency of dispersion and arrangement of the conductive particles can be increased. In this way, as shown in FIG. 6(b), the upper electrode 7 in which the conductive particles 12 are adsorbed to the adsorption portion 5, that is, the conductive particle-attached electrode 20 is obtained.

The applied electric field strength can be 0.1 to 30 kV/cm, may be 0.5 to 30 kV/cm, or may be 1 to 20 kV/cm.

Application of the electric field may be continuous or intermittent.

The application time of the electric field can be appropriately set depending on the amount of conductive particles to be attracted to the attraction part.

The electrode 20 with conductive particles obtained through the second step may be used as it is as a base material on which the conductive particles are spaced apart and arranged two-dimensionally, or it may be used to transfer the conductive particles onto a predetermined base material. Good too.

Further, when the suction part 5 has an opening pattern, the upper electrode 7 in which the conductive particles 12 are accommodated in the openings of the suction part 5, that is, the electrode 20 with conductive particles, can be obtained by performing the second step in the same manner as described above. It will be done.

The dispersion method according to the present embodiment when the adsorption section 5 has an opening pattern includes a step ( The method may further include a step (hereinafter also referred to as an excess particle removal step). The excess particle removal step can be performed before the conductive particles accommodated in the openings are transferred onto a predetermined adhesive base material. In this case, the particles removed from the adsorption part may be collected and recycled, and it is preferable to collect and recycle at least the conductive particles among the surplus particles.

Examples of methods for removing excess particles include physical removal means such as air blow, brush, and squeegee, and electrostatic removal means such as ionizer.

In the method for dispersing conductive particles of the present embodiment, the conductive particles adsorbed on the adsorption part are electrostatically adsorbed to a second adsorption part having an insulating property disposed to face the adsorption part (hereinafter referred to as a step). (also referred to as 3 steps).

<3rd process>
The electrostatic adsorption device used in the third step uses an electrode 20 with conductive particles obtained through the second step in place of the lower electrode 4 in the electrostatic adsorption device 1 described above, and uses conductive particles in place of the upper electrode 7. The electrostatic adsorption device 1 may have the same configuration as the electrostatic adsorption device 1 except for using a third electrode having an insulating second adsorption portion disposed to face the adsorption portion 5 of the attached electrode 20.

The third electrode can be composed of an electrode body and a second suction part.

As the electrode body constituting the third electrode, one having static electricity dissipation properties or conductivity can be used. For example, a material having a surface resistivity of 1×10 ¹³ Ω or less can be used, and specific examples include metal, glass, and the like. The shape of the electrode body is not particularly limited, but may be, for example, flat, rolled, or the like.

An insulating material can be used as the material of the second suction part. For example, a material having a surface resistivity of more than 1×10 ¹³ Ω can be used, and specific examples thereof include resins such as polytetrafluoroethylene. The shape of the second suction part is not particularly limited, and may be a membrane or film formed on the surface of the electrode body, or may be a film that is separable from the electrode body.

In the electrostatic adsorption device described above, by forming an electric field between the electrode with conductive particles and the third electrode, the conductive particles of the electrode with conductive particles are charged to a polarity opposite to that of the third electrode. state, rises due to electrostatic attraction, and is attracted to the second attraction part. As a result, an adsorption portion to which the conductive particles are adsorbed is obtained.

By providing the third step, it becomes easier to adjust the particle density and to make the intervals between the conductive particles more uniform.

Furthermore, due to the reduction in the electric field caused by the adsorption of conductive particles to the insulating second adsorption part, the electrostatic adsorption of the conductive particles can be stopped when a predetermined amount of conductive particles are adsorbed to the second adsorption part. This makes it easier to achieve the above effects. In other words, the strength of the electric field between the electrode with conductive particles and the third electrode becomes smaller as more conductive particles adhere to the second adsorption part, so that there are no conductive particles on the surface of the electrode with conductive particles. In addition, the flight of conductive particles can be stopped by sufficiently reducing the electric field between the electrodes. By utilizing this phenomenon, for example, if we can supply a sufficient amount of conductive particles by making the electrode with conductive particles movable, we can move the conductive particles to the adsorption part of the third electrode until the electric field becomes sufficiently weak. It can be adsorbed. At this time, all conductive particles are considered to be charged with the same polarity, and even if a conductive particle flies to the same place as a conductive particle that has already been adsorbed, the conductive particle will avoid collision due to electrostatic repulsion. It can be moved and adsorbed to areas where conductive particles are not adsorbed. Therefore, by providing the third step, in particular, it is possible to attach a sufficient number of conductive particles to the adsorption part and to make the intervals between the particles approximately equal, that is, to achieve the conductive particle density and uniform dispersion. It is expected that both can be achieved at a high level.

The second adsorption section may be provided with an opening pattern (a plurality of openings) that opens toward the arrangement section. The shape of such an adsorption portion may be a membrane or film formed on the surface of the electrode body, or may be a film that is separable from the electrode body.

The second adsorption section having an opening pattern can be designed similarly to the above-mentioned adsorption section 5 having an opening pattern, except that it is insulative.

Further, the above-mentioned surplus particle removal step can be performed.

In the electrostatic adsorption device used in the third step, the third electrode may be movable, and in this case, it becomes easy to continuously supply the adsorption portion that adsorbs the conductive particles. For example, a third electrode can be provided on the surface of a belt or a cylindrical roller. Alternatively, the second suction section may be a film that is continuously supplied.

In the electrostatic adsorption device described above, the first electrode, the second electrode, the electrode with conductive particles, and the third electrode are arranged on the lower side and the upper side with respect to the direction of gravity, respectively. In the method for dispersing conductive particles, the moving direction of the blended particles or conductive particles may be horizontal or may be inclined with respect to the direction of gravity. Even in these cases, the first electrode, second electrode, and third electrode can have the same configuration as above. Furthermore, the first step, the second step, and the third step may be performed continuously.

According to the method for dispersing conductive particles of the present embodiment, since the conductive particles can be spaced apart and arranged two-dimensionally, the method can be applied to various electronic materials such as conductive materials.

[Electrostatic adsorption device]
The electrostatic adsorption device of the present embodiment includes a first electrode having an arrangement section having static dissipative properties or conductivity, and a second electrode having an adsorption section, and the arrangement section and the adsorption section are opposed to each other. The arrangement part has a recess opening toward the suction part, and the recess has an inner wall surface that is tapered such that the opening width increases toward the suction part. The adsorption part may have static electricity dissipation properties or conductivity, or may have insulation properties.

The electrostatic adsorption device of this embodiment can have the same configuration as the electrostatic adsorption device used in the above-described method for dispersing conductive particles, and can function as a dispersion device for conductive particles.

FIG. 7 is a diagram showing an example of an electrostatic adsorption device. This electrostatic adsorption device has an arrangement part in which a plurality of inverted rectangular thrust-shaped recesses 30g are provided in a grid pattern as shown in (g-1) and (g-2) of FIG. 4 as a first electrode. 2g, and has an adsorption part 5a provided on the side surface of the cylindrical roller 40 as a second electrode, and the arrangement part 2g can be horizontally moved in the direction of arrow B (or other directions). , the suction portion 5a can rotate in the direction of arrow A (or in the opposite direction). Further, the arrangement portion 2g may be fixed, and the suction portion 5a may rotate and move horizontally.

The present disclosure can also provide the following inventions [1] to [6].
[1] By forming an electric field between a first electrode having an arrangement part having static electricity dissipative property or conductivity and a second electrode having an adsorption part facing the arrangement part, The method further comprises a step of reciprocating blended particles, in which conductive particles having a particle size smaller than the mediator particles are attached to the mediator particles, between the arrangement part and the adsorption part to adsorb the conductive particles to the adsorption part, The placement part has a recess that opens toward the suction part, the recess has an inner wall surface that is tapered such that the opening width increases toward the suction part, and the blended particles are arranged in the recess. , a method for dispersing conductive particles.
[2] The method for dispersing conductive particles according to [1] above, wherein the particle size of the mediating particles is 10 to 100 times the particle size of the conductive particles.
[3] The method for dispersing conductive particles according to [1] or [2] above, wherein the conductive particles have a particle size of 2 to 50 μm.
[4] The method for dispersing conductive particles according to any one of [1] to [3] above, wherein the adsorption section has an opening pattern that opens toward the arrangement section.
[5] A first electrode having an arrangement part having static electricity dissipative property or conductivity, and a second electrode having an adsorption part, the arrangement part and the adsorption part can face each other, and the arrangement part An electrostatic adsorption device, wherein the recess has a recess that opens toward the suction part, and the recess has an inner wall surface that is tapered such that the opening width increases toward the suction part.
[6] The electrostatic adsorption device according to [5] above, wherein the adsorption section has an opening pattern that opens toward the arrangement section.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Preparation of blended particles]
(Preparation example 1)
In a glass container, 1200 parts by mass of carbon particles with a diameter of 120 to 150 μm (manufactured by Nippon Carbon Co., Ltd., product name "NICA beads ICB-15020") as mediating particles, and plastic with a diameter of 2.5 μm as conductive particles. Compounded particles P were obtained by adding 1 part by mass of conductive coated particles having an average particle size of 3 μm and having been subjected to Ni plating on the surface of the core particles, and shaking the container to mix. The obtained blended particles P were observed using a scanning electron microscope, and it was confirmed that the conductive particles were attached to the surface of the mediator particles.

[Dispersion arrangement of conductive particles]
(Example 1)
A device having the same configuration as the electrostatic adsorption device 1 according to the embodiment described above was prepared. In this device, as shown in FIG. 8(a), the lower electrode ₄ is a copper plate (depth: A stainless steel flat plate (10 cm deep x 15 cm wide x 1 mm thick) was used as the upper electrode 7, and the distance _d1 between the electrodes was set to 3 mm.

10 to 11 mg of the blended particles P obtained in Preparation Example 1 were placed in the recessed part of the copper plate (lower electrode), and a voltage of 0.7 kV was applied between the electrodes to move the blended particles up and down. Thereby, a stainless steel plate with conductive particles was obtained, in which the conductive particles were adsorbed at intervals on the surface of the stainless steel plate.

(Reference example 1)
A device having the same configuration as the electrostatic adsorption device 1 according to the embodiment described above was prepared, except that the arrangement portion was not provided with a recess. In this device, as shown in FIG. 8(b), a copper plate (depth 10 cm x width 10 cm x thickness 0.5 mm) is used as the lower electrode 4, and a stainless steel plate (depth 10 cm x width 15 cm x thickness 0.5 mm) is used as the upper electrode 7. 1 mm), and the inter-electrode distance _d2 was set to 3 mm.

10 to 11 mg of the blended particles P obtained in Preparation Example 1 were placed in a 6 mm square area of the copper plate (lower electrode), and a voltage of 0.8 kV was applied between the electrodes to move the blended particles up and down. Thereby, a stainless steel plate with conductive particles was obtained, in which the conductive particles were adsorbed at intervals on the surface of the stainless steel plate.

[Evaluation of adhesion density of conductive particles]
Regarding the stainless steel flat plate with conductive particles, the center point is the part directly above the center of the area where the blended particles are arranged, and the range of 3 mm to the left and right from the center point (S 11 in Fig. 8 (a), S ₁₁ in Fig. 8 (b) The adhesion density of conductive particles in S ₁₂ ) was measured using the following procedure. First, a cellophane tape was attached to an area including the above range of a stainless steel flat plate with conductive particles, and the conductive particles were transferred to the cellophane tape. Next, this cellophane tape was observed at 400 times magnification using a microscope, and the number of conductive particles was counted to calculate the number of conductive particles per 1 mm ² as particle density.

It was confirmed that the stainless steel plate with conductive particles obtained in Example 1 had a particle density of 2200 particles/mm ² to 3050 particles/mm ² in a range of 3 mm left and right from the center point. On the other hand, the stainless steel plate with conductive particles obtained in Reference Example 1 had a particle density of 1100 particles/mm ² to 1250 particles/mm ² in a range of 3 mm left and right from the center point.

DESCRIPTION OF SYMBOLS 1... Electrostatic adsorption device, 2... Placement part, 3... Electrode main body, 4... Lower electrode (first electrode), 5... Adsorption part, 6... Electrode main body, 7... Upper electrode (second electrode), 8 ... Power source, 9... Control unit, 10... Mediator particle, 12... Conductive particle, 20... Electrode with conductive particle, 30... Concave portion, P... Mixed particle.

Claims (6)

By forming an electric field between a first electrode having an arrangement part having static dissipative or conductive properties and a second electrode having an adsorption part facing the arrangement part, , a step of causing mixed particles, in which conductive particles having a smaller particle size than the mediating particles are attached to the mediating particles, to be reciprocated between the arrangement portion and the adsorption portion to adsorb the conductive particles to the adsorption portion; Equipped with
The placement part has a recess that opens toward the suction part,
The recess has an inner wall surface that is tapered such that the opening width increases toward the suction part,
A method for dispersing conductive particles, wherein the blended particles are placed in the recesses. The method for dispersing conductive particles according to claim 1, wherein the particle size of the mediating particles is 10 to 100 times the particle size of the conductive particles. The method for dispersing conductive particles according to claim 1 or 2, wherein the conductive particles have a particle size of 2 to 50 μm. The method for dispersing conductive particles according to claim 1 or 2, wherein the adsorption section has an opening pattern that opens toward the arrangement section. a first electrode having an arrangement part having static dissipative properties or conductivity;
a second electrode having an adsorption part;
The arrangement part and the suction part can face each other,
The placement part has a recess that opens toward the suction part,
In the electrostatic adsorption device, the recess has an inner wall surface that is tapered such that the opening width increases toward the adsorption part side. The electrostatic adsorption device according to claim 5, wherein the adsorption section has an opening pattern that opens toward the arrangement section.

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