JP2023147928A - Coating liquid for forming conductive film and method for producing the same, and method for producing substrate with conductive film - Google Patents

Abstract

To provide a coating liquid including particles, enabling the formation of a film with increased conductivity.SOLUTION: A coating liquid contains tin oxide particles, a dispersant, a binder, and an organic solvent, with the coating liquid having an average particle size of 150-400 nm. The dispersant used here is a titanate coupling agent or an anionic surfactant. A film formed using such a coating liquid has a low haze. The film also has high conductivity.SELECTED DRAWING: None

Description

The present invention relates to a coating liquid for forming a conductive film, a method for manufacturing the same, and a method for manufacturing a substrate with a conductive film.

A conductive film can be formed on a substrate using a coating liquid containing particles containing tin oxide. Since the conductive film prevents charging, it is difficult for dirt such as dust to adhere to the surface. Such antistatic conductive films are used in smart phones, car navigation touch panels, and the like. In these applications, the screen and parts need to be easily visible. Therefore, a conductive film with low haze is required. If tin oxide-containing particles with a small average particle diameter (about 100 nm) are easily dispersed in a solvent or binder, the haze of the film will be low. Examples of coating liquids capable of forming such a film include coating liquids containing tin oxide-containing particles whose surface has been treated with an organic coupling agent and a surfactant (see, for example, Patent Document 1).

Furthermore, particles in which the surface of a core material such as an inorganic oxide is coated with tin oxide are known (for example, Patent Document 2). The particle size of these particles can be adjusted according to the particle size of the core material. When the particle surface is treated with a silane coupling agent, the particle can be dispersed in an organic solvent.

International Publication No. 2001-018137 JP2018-085231A

In Patent Document 1, a conductive film is formed using a coating liquid containing a surfactant and tin oxide-containing particles whose surface is treated with an organic coupling agent. Therefore, the conductive film has high transparency. However, before adding the binder, the average particle size of the tin oxide-containing particles in the dispersion is small. Therefore, the particles in the coating liquid and film are also small. As a result, the conductivity of the membrane is low.

The particles coated with tin oxide of Patent Document 2 have a large average particle diameter. However, the conductivity of the particles is low because the tin oxide layer coated on the particle surface is thin. Further, when the silane coupling agent used as a dispersant in Patent Document 2 is applied to particles containing tin oxide, the conductivity of a film containing the particles becomes low.

Therefore, an object of the present invention is to provide a coating liquid containing particles that can increase the conductivity of a film.

Therefore, the present invention includes tin oxide-containing particles, a dispersant, a binder, and an organic solvent, and the average particle diameter of the coating liquid is 150 to 400 nm. Here, a titanate coupling agent or an anionic surfactant was used as a dispersant. A film formed using such a coating liquid has a low haze. Furthermore, the film has high conductivity.

Furthermore, it is preferable that the coating liquid contains silica particles.

Further, it is preferable to use a titanate coupling agent and an anionic or cationic surfactant as a dispersant.

In addition, the manufacturing method of the coating liquid includes a step (mixing step) of mixing tin oxide-containing particles, a dispersant, and an organic solvent to prepare a suspension (mixing step), and a step of disintegrating the mixed liquid to produce a tin oxide-containing particle. The method includes a step of preparing a dispersion (disintegration step) and a step of adding a binder to the dispersion (addition step). In the crushing step, the average particle diameter of the tin oxide-containing particles is adjusted to 200 to 500 nm.

The present invention is a coating liquid containing tin oxide-containing particles (hereinafter referred to as tin oxide particles), a dispersant, a binder, and an organic solvent. Here, the average particle size of the coating liquid measured by a dynamic light scattering method (hereinafter referred to as the average particle size of the coating liquid) is 150 to 400 nm. If this average particle diameter is less than 150 nm, the grain boundary resistance becomes high, so that the conductivity of the conductive film (hereinafter simply referred to as film) tends to decrease. On the other hand, if the average particle diameter is larger than 400 nm, the area in which the particles come into contact with each other in the film is small, which may make it difficult to form a conductive path. Moreover, when the average particle diameter is larger than 400 nm, the particles in the film tend to scatter light. A film containing such particles will have a high haze. When this average particle diameter is smaller than 350 nm, the haze of the film becomes even lower.

When the dispersant is a titanate coupling agent or an anionic surfactant, the conductivity of the film is increased. Therefore, it is easy to apply the coating liquid. In particular, even if a binder is added to a dispersion containing a titanate coupling agent, the viscosity of the coating liquid is unlikely to increase. If only an organometallic coupling agent such as silicon (Si), zirconium (Zr), aluminum (Al), etc. other than the titanate coupling agent is used as a dispersant, the conductivity of the film will decrease. The decrease in conductivity is thought to be affected by differences in metal elements and differences in hydrolysis rate.

Anionic surfactants have a hydrophilic group that ionizes and becomes an anion, and a hydrophobic group. This hydrophilic group is easily adsorbed on the surface of tin oxide particles (hereinafter referred to as particle surface). The hydrophobic groups of the surfactant adsorbed on the particle surface tend to be unevenly distributed on the solvent side. Therefore, the tin oxide particles to which the surfactant has been adsorbed are easily dispersed in an organic solvent or binder. When an anionic surfactant is used as a dispersant, the viscosity of the coating liquid becomes higher than when a titanate coupling agent is used. However, anionic surfactants are generally less expensive than titanate coupling agents. Therefore, when using an anionic surfactant, costs can be reduced. Further, in this case, the haze and conductivity of the film are equivalent to those when using a titanate coupling agent. Examples of anionic surfactants include phosphoric acid ester type, fatty acid type, sulfuric acid ester type, sulfonic acid type, and carboxylic acid type. Among these, when a phosphate ester type surfactant is used, tin oxide particles are easily dispersed in an organic solvent or a binder. When only a cationic or nonionic surfactant is used, tin oxide particles cannot be dispersed in an organic solvent.

When the content of the dispersant is 1.3 parts by mass or more with respect to 100 parts by mass of tin oxide particles, the tin oxide particles are easily dispersed in the organic solvent or binder. Therefore, the haze of the film becomes low. On the other hand, if this content is 2 parts by mass or less, the amount of dispersant coated on the particles decreases. Therefore, the conductivity of the film becomes high.

When the content of the dispersant is 0.5 mg or more per 1 m ² of surface area of the tin oxide particles, the tin oxide particles are easily dispersed in the organic solvent or binder. Therefore, the haze of the film becomes low. On the other hand, if this content is 5 mg or less, the amount of dispersant coated on the particles will be reduced. Therefore, the conductivity of the film becomes high.

When using a titanate coupling agent, costs can be reduced by substituting a part of the titanate coupling agent with an anionic or cationic surfactant. Even if the content of the titanate coupling agent in the coating liquid is reduced in this way, the performance of the titanate coupling agent (particularly the effect of preventing the viscosity of the coating liquid from becoming high) can be exhibited. When the amount of dispersant in the coating solution is 1.3 parts by mass or more based on 100 parts by mass of particles, the ratio of the titanate coupling agent to these surfactants (amount of titanate coupling agent/surfactant) When the amount) is 0.4 or more, the performance of the titanate coupling agent is likely to be exhibited. Note that the cationic surfactant has a hydrophobic group and a hydrophilic group that ionizes to become a cation. Examples of cationic surfactants include quaternary ammonium salts and amine salts.

The binder may be any binder as long as it can be dissolved in an organic solvent and form a conductive film. Examples include thermoplastic resins, thermosetting resins, and ultraviolet curable resins. A mixture of multiple types of binders may be used.

When a film is formed using a coating liquid containing silica particles, the film has high conductivity and low haze. This is presumed to be due to two reasons. The first reason is that the film is formed with the components of the coating solution homogeneously mixed. Such a film is homogeneous in structure (density and surface roughness) and composition. As a result, it is presumed that the conductivity of the film is high and the haze of the film is low. Another reason is that the silica particles push out the tin oxide particles in the film. When the tin oxide particles exist along the periphery of the silica particles, a conductive path is easily formed. Furthermore, when the coating liquid contains silica particles, the film surface becomes slippery, making it easier to prevent the films from sticking to each other. Therefore, handling of the membrane becomes easier. When the average particle diameter of the silica particles is 70 nm or more, it is easy to push out the tin oxide particles in the film. On the other hand, when the average particle diameter of the silica particles is 400 nm or less, the haze of the film becomes low. The average particle diameter of the silica particles is preferably 150 nm or less. The average particle diameter of silica particles can be measured using a transmission electron microscope (TEM).

Any organic solvent may be used as long as it can dissolve the dispersant and binder. Components other than the solvent are treated as solids.

The lower the solid content concentration of the coating liquid, the lower the viscosity of the coating liquid. Therefore, this concentration is preferably 40% by weight or less. On the other hand, if this concentration is 20% by weight or more, it is easy to form a thick film. Thick films have high hardness and conductivity.

When the concentration of tin oxide particles in the solid content of the coating liquid is 40% by weight or more, conductive paths are likely to be formed.

When the solid binder concentration in the coating liquid is 10% by weight or more, tin oxide particles are easily dispersed in the coating liquid and the binder. This concentration is preferably 20% by weight or more. On the other hand, if this concentration is 45% by weight or less, the conductivity of the film will be high. This concentration is more preferably 35% by weight or less.

When the solid silica particle concentration in the coating liquid is 5% by weight or more, conductive paths are likely to be formed. On the other hand, if this concentration is 50% by weight or less, the haze of the film will be low. Furthermore, the conductivity of the film is increased. When this concentration is 20% by weight or less, the film tends to adhere to the base material.

The tin oxide particles will be explained below. When tin oxide particles formed by combining a plurality of primary particles are used, the haze is reduced. When the tin oxide content of the particles is 90% by weight or more in terms of SnO ₂ , grain boundary resistance is low. Therefore, the conductivity of the film becomes high.

The smaller the primary particle diameter of the tin oxide particles, the lower the haze of the film. For the purpose of reducing the haze of the film, the primary particle diameter of the tin oxide particles is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. On the other hand, when the primary particle size is large, the grain boundary resistance of the tin oxide particles becomes low. Therefore, the resistance of the film is also lowered. For the purpose of lowering the resistance of the film, the primary particle diameter is preferably 20 nm or more.

The lower the specific surface area of the tin oxide particles, the lower the grain boundary resistance of the tin oxide particles. Therefore, this specific surface area is preferably 100 m ² /g or less, more preferably 50 m ² /g or less. On the other hand, when the specific surface area is 30 m ² /g or more, the haze of the film becomes low. This specific surface area is more preferably 35 m ² /g or more.

Tin oxide particles doped with antimony or phosphorus have high conductivity. In particular, antimony-doped tin oxide particles have high electrical conductivity. When the amount of antimony (Sb) doped is 2 to 6% by weight in terms of Sb ₂ O ₃ , the conductivity of the tin oxide particles becomes high. On the other hand, phosphorus-doped tin oxide particles do not have as high conductivity as antimony-doped tin oxide particles. However, phosphorus has less of a burden on the environment than antimony. When the doping amount of phosphorus (P) is 4 to 6% by weight in terms of P ₂ O ₅ , the conductivity of the tin oxide particles becomes high.

The method for manufacturing the coating liquid will be described below. First, a tin oxide-containing powder (hereinafter referred to as tin oxide powder), a dispersant, and an organic solvent are mixed to prepare a suspension of tin oxide powder [mixing step]. A dispersion of tin oxide particles is prepared by crushing the tin oxide powder in the suspension [crushing step]. During crushing, the average particle size of the dispersion (ie, the average particle size of the tin oxide particles) is adjusted to 200 nm to 500 nm. A coating liquid is prepared by adding a binder to this dispersion liquid (addition step).

When the primary particle size of the tin oxide powder is 500 nm or less, the tin oxide powder can be easily crushed into an average particle size of 500 nm or less in the crushing step.

The lower the specific surface area of the tin oxide powder, the lower the grain boundary resistance of the tin oxide particles. Therefore, this specific surface area is preferably 100 m ² /g or less, more preferably 50 m ² /g or less. On the other hand, when this specific surface area is 2 m ² /g or more, it is easy to crush the tin oxide powder so that the average particle size becomes 500 nm or less in the crushing step. When this specific surface area is 30 m ² /g or more, the haze of the film becomes low. This specific surface area is more preferably 35 m ² /g or more.

As the tin oxide powder, for example, tin oxide powder produced by the method described in Japanese Patent Application Laid-Open No. 6-76636 and Japanese Patent Application No. 62-51008 can be used. Furthermore, methods for preparing tin oxide powder include a method in which a tin ion solution is neutralized, and a method in which a solution of tin chloride dissolved in heated water is added and hydrolyzed. The method of neutralization will be explained below. After ionizing tin oxide by adding acid, the ions are neutralized using a base. This yields a tin oxide precipitate. By drying and firing this, tin oxide powder is obtained. When neutralizing, antimony trioxide also ionizes and can be neutralized (co-precipitated) together with tin ions. Co-precipitation allows antimony to be doped into the tin oxide powder. Doping 2 to 6% by weight of antimony with respect to the total amount of tin oxide particles to be prepared increases the conductivity of the tin oxide particles.

In the mixing step, tin oxide powder, a dispersant, and an organic solvent are mixed to prepare a suspension of tin oxide powder. Here, a titanate coupling agent or an anionic surfactant is mixed as a dispersant (referred to as dispersant A). With such a dispersant, the tin oxide particles can be easily dispersed in the organic solvent after the crushing step. It is preferable to mix and dissolve the dispersant in an organic solvent to prepare a dispersant solution, and then mix the tin oxide powder and the dispersant solution. With this method, the surface of the tin oxide particles is uniformly treated with the dispersant in the crushing step.

A dispersion of tin oxide-containing particles is prepared by crushing the tin oxide powder in the suspension. When tin oxide powder is crushed, it becomes tin oxide particles. At this time, the average particle diameter of the tin oxide particles is adjusted to 200 to 500 nm. The average particle diameter of tin oxide particles can be measured by a centrifugal sedimentation method (the measurement method is different from that of the coating liquid). When the average particle diameter of tin oxide is 200 nm or more, anionic surfactants and titanate coupling agents are easily adsorbed on the surface of tin oxide particles. Therefore, tin oxide particles can be dispersed in an organic solvent. When only a cationic or nonionic surfactant is used, tin oxide particles having an average particle diameter of 200 nm or more cannot be dispersed in an organic solvent. When the average particle size of the tin oxide particles is 200 nm or more, the average particle size of the coating liquid becomes 150 nm or more. If the average particle size of the tin oxide particles is less than 200 nm, the average particle size of the coating liquid will be less than 150 nm. Therefore, it becomes difficult for tin oxide particles to form conductive paths in the film. On the other hand, when the average particle size of the tin oxide particles is 500 nm or less, the average particle size of the coating liquid becomes 400 nm or less. With this average particle diameter, the haze of the film will be low.

The tin oxide powder can be pulverized using a medium mill such as a bead mill, a high-speed stirrer, a high-pressure homogenizer, an ultrasonic homogenizer, a wet pulverizer such as a jet mill, and the like. In particular, when a bead mill is used, it is easy to crush the tin oxide powder in the suspension. When using a bead mill, the crushing time, circumferential speed, and bead filling rate need to be appropriately adjusted depending on the scale and shape of the bead mill used. The bead diameter is adjusted appropriately according to the circumferential speed. Glass or zirconia beads are easily available. If the beads used are inorganic oxides such as zirconia or alumina, the energy imparted to the tin oxide powder is high, making it easier to crush the tin oxide powder. After crushing, coarse particles can be removed by filtering the dispersion using a stainless wire mesh or the like.

A coating liquid is prepared by adding a binder to the above-mentioned dispersion of tin oxide particles. Even if a binder is added to this dispersion, the tin oxide particles are difficult to aggregate. Even if they aggregate, the aggregated tin oxide particles are redispersed by irradiating the coating liquid with ultrasonic waves.

By additionally adding the above-mentioned dispersant before irradiating the ultrasonic wave, redispersion of the tin oxide particles is promoted (the dispersant added here is referred to as dispersant B). The type of dispersant may be the same as or different from the dispersant already contained in the dispersion. At this time, when the total amount of the dispersant contained in the coating liquid is 1.3 parts by mass or more based on 100 parts by mass of tin oxide particles, the tin oxide particles can be easily dispersed in the organic solvent. On the other hand, when this total amount is 2 parts by mass or less based on 100 parts by mass of particles, the amount of dispersant coated on the particles decreases, so that the conductivity of the film increases.

A film-coated base material can be manufactured by applying the above-mentioned coating liquid onto a base material and drying it. The substrate may be any material as long as it can form a uniform liquid film and can withstand the drying temperature. Examples of the coating method include a bar coater method, a dip method, a spray method, a spinner method, a roll coating method, a gravure coating method, a slit coating method, a pressure coating method, and the like. The average film thickness can be selected as appropriate depending on the application. When the average film thickness is 50 nm or more, rapid voltage changes due to static electricity can be easily suppressed. The average film thickness is preferably 80 nm or more. When the average film thickness is 1000 nm or less, transparency becomes high. The average film thickness is preferably 300 nm or less.

[Example 1]
The method for preparing the coating liquid will be specifically described below. Table 1 also shows the preparation conditions for the coating liquids of other Examples and Comparative Examples.

First, tin oxide powder was prepared as follows. 153 g of potassium stannate was dissolved in 343 g of water. 9.3 g of tartarite was added to this and dissolved. This was added together with nitric acid to 50° C. hot water over 12 hours so as to maintain the pH at 8.5. This gave a sol. The particles were filtered from this sol and washed. Tin oxide powder was obtained by drying the particles at 100°C for 5 hours and then calcining them at 550°C for 3 hours.

[Mixing process]
Next, tin oxide powder, dispersant A, and an organic solvent were mixed to prepare a suspension. 84 g of 2-butanone (manufactured by Hayashi Pure Chemical Industries, Ltd., organic solvent) as an organic solvent and 1.5 g of PreneAct (registered trademark) 9SA (manufactured by Ajinomoto Fine Techno Co., Ltd.) as a dispersant (titanate coupling agent) were mixed. A dispersant solution was prepared by stirring this for 10 minutes. A suspension was prepared by mixing 85.5 g of this dispersant solution and 43 g of tin oxide powder in a 2 L glass beaker.

[Crushing process]
In this step, the tin oxide powder in the suspension is crushed. First, 255 g of glass beads BZ-06 (manufactured by As One, beads diameter: 0.5 mm) was added to 128.5 g of the suspension. Tin oxide particles were prepared by crushing tin oxide powder in a suspension (tin oxide powder) using a batch type bead mill Easy Nano RMBII type. Crushing was continued until the average particle size of the tin oxide particles became 340 nm (the average particle size of the tin oxide particles listed in Table 1) (also in other Examples and Comparative Examples, the average particle size of the tin oxide particles was 340 nm). Crushing was continued until the average particle diameter of the tin oxide particles was reached as shown in Table 1.) The peripheral speed of the bead mill was 12 m/s. Glass beads were separated from the suspension using a stainless wire mesh with a mesh size of 44 μm. A dispersion liquid (solid content concentration: 35.0% by weight) was prepared by adding 2-butanone to this.

[Addition process]
In this step, a binder is added to the dispersion. 7.62 g of acrylic resin (Clarity (registered trademark) LA2270 manufactured by Kuraray Co., Ltd.) as a binder was dissolved in 17.77 g of 2-butanone. This was added to 56.70 g of the dispersion being stirred. This dispersion was stirred for 5 minutes. Dispersion of 6.86 g of silica sol surface-treated with 3-methacryloxypropyltrimethoxysilane (solvent: 4-methyl-2-pentanone, SiO ₂ concentration: 37%, average particle diameter measured by SEM: 140 nm) as silica particles added to. After stirring this dispersion for 5 minutes, 0.3 g of Prysurf (registered trademark) A212C (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added as dispersant B (phosphate ester type anionic surfactant in Example 1) to the dispersion. Added. After stirring the dispersion for 5 minutes, 10.75 g of 2-butanone was added to the dispersion. After stirring this dispersion for 60 minutes, the dispersion was irradiated with ultrasonic waves for 60 seconds using an ultrasonic dispersion machine (Horn type 5281 manufactured by Kaijo). A coating solution was prepared by filtering this dispersion using a stainless wire mesh.

After the coating liquid was heated to 25° C., the viscosity of the coating liquid was measured using a viscometer model TVB-10 (manufactured by Toki Sangyo Co., Ltd.). Measurement results of other Examples and Comparative Examples are also shown in Table 1.

The average particle diameter of the coating liquid was measured as follows. 9 g of 2-butanone was added to 1 g of the coating solution. A measurement sample was prepared by irradiating this coating liquid with ultrasonic waves for 60 seconds using a bath-type ultrasonic cleaner. A glass cell was filled with the measurement sample, and the volume average particle diameter of the coating liquid was measured using a dynamic light scattering type particle diameter measuring device (Zetasizer Nano ZS manufactured by Malvern). Measurement results of other Examples and Comparative Examples are also shown in Table 1.

This coating liquid was applied onto a polyester film (Cosmoshine (registered trademark) A4360 manufactured by Toyobo Co., Ltd.) by a bar coater method. The coating solution was dried for 20 minutes at 25°C and 50RH% to obtain a film-coated base material. The surface resistance and optical properties of this film-coated base material were measured as follows. The measurement results of other Examples and Comparative Examples are also shown in Table 2.

(Surface resistance)
The surface resistance of the film was measured using a surface resistance measuring device (Hirester UX MCP-HT800 manufactured by Nitto Seiko Analytech).

(optical properties)
The haze of the film-coated substrate was measured using a haze meter (HZ-V3 manufactured by Suga Test Instruments Co., Ltd.).

[Example 2]
A suspension and a dispersion were prepared in the same manner as in Example 1, except that 1.3 g of Plysurf (registered trademark) A212C was added as dispersant A in the mixing step.
In the addition step, the same as Example 1 was used, except that this dispersion was used and 0.3 g of Prenact (registered trademark) 9SA (manufactured by Ajinomoto Fine Techno, Inc., titanate coupling agent) was added as dispersant B. A coating solution and a substrate with a film were obtained.

[Example 3]
A coating liquid and a film-coated substrate were obtained in the same manner as in Example 1, except that in the addition step, silica sol with an average particle diameter of 160 nm was used as the silica particles.

[Example 4]
A coating liquid and a film-coated substrate were obtained in the same manner as in Example 1, except that in the addition step, silica sol with an average particle diameter of 300 nm was used as the silica particles.

[Example 5]
In the mixing step, a suspension and a dispersion were prepared in the same manner as in Example 1, except that the amount of Prenact 9SA added was 1.4 g. In the addition step, a coating solution and a film-coated substrate were obtained in the same manner as in Example 1, except that this dispersion was used and 0.3 g of PrenAct 9SA was added as dispersant B.

[Example 6]
In the mixing step, a suspension and a dispersion were prepared in the same manner as in Example 1, except that the amount of Prenact 9SA mixed was 2.3 g. A coating solution and a film-coated substrate were obtained in the same manner as in Example 1, except that this dispersion was used in the addition step and dispersant B was not added.

[Example 7]
A coating liquid and a film-coated substrate were obtained in the same manner as in Example 2, except that 0.3 g of Plysurf A212C was added as dispersant B in the addition step.

[Example 8]
A coating solution and a film-coated substrate were obtained in the same manner as in Example 1, except that 0.3 g of Filanol PA-075F (manufactured by NOF Corporation) was mixed as dispersant B in the addition step.

[Example 9]
In the addition step, 10.15 g of Clarity LA2270 as a binder was dissolved in 23.70 g of 2-butanone. This was added to 56.70 g of the dispersion being stirred. No silica particles were added to this dispersion. After stirring this dispersion for 5 minutes, 0.3 g of Plysurf A212C as dispersant B was added to the dispersion. After stirring this dispersion for 5 minutes, 9.15 g of 2-butanone was added to the dispersion. A coating liquid and a film-coated base material were obtained in the same manner as in Example 1 except for the above.

[Example 10]
In the addition step, 5.08 g of Clarity LA2270 as a binder was dissolved in 11.85 g of 2-butanone. This was added to 56.70 g of the dispersion being stirred. To this dispersion, 13.72 g of silica sol surface-treated with 3-methacryloxypropyltrimethoxysilane (solvent: 4-methyl-2-pentanone, SiO ₂ concentration 37%, 140 nm [measured by SEM]) was added as silica particles. Added. After stirring this dispersion for 5 minutes, 0.3 g of Plysurf A212C as dispersant B was added to the dispersion. After stirring this dispersion for 5 minutes, 12.35 g of 2-butanone was added to the dispersion. A coating liquid and a film-coated base material were obtained in the same manner as in Example 1 except for the above.

[Example 11]
A suspension and a dispersion were prepared in the same manner as in Example 1, except that 2.6 g of Plysurf A212C was added as dispersant A in the mixing step. A coating solution and a film-coated substrate were obtained in the same manner as in Example 1, except that this dispersion was used in the addition step and dispersant B was not added.

[Example 12]
A coating solution and a film-coated substrate were obtained in the same manner as in Example 1, except that an acrylic resin (ACRYDIC A-166 manufactured by DIC Corporation) was used as the binder resin in the addition step.

[Comparative example 1]
In the crushing step, crushing was continued until the average particle diameter of the tin oxide particles became 190 nm. Other than that, a coating liquid and a film-coated substrate were obtained in the same manner as in Example 1.

[Comparative example 2]
In the crushing step, crushing was continued until the average particle size of the tin oxide powder reached 550 nm. Other than that, a coating liquid and a film-coated substrate were obtained in the same manner as in Example 1.

[Comparative example 3]
In the mixing step, the suspension was prepared in the same manner as in Example 1, except that 1.3 g of a silane coupling agent (3-methacryloxypropyltrimethoxysilane, KBM-503, manufactured by Shin-Etsu Silicone Co., Ltd.) was added as dispersant A. Obtained. In the crushing step, the tin oxide powder in the suspension was crushed under the same conditions as in Example 1 except that this suspension was used. Even if the crushing was continued, the average particle size of the tin oxide powder decreased only to 570 nm. Glass beads were separated from the suspension using a stainless wire mesh with a mesh size of 44 μm. A dispersion liquid (solid content concentration: 35.0% by weight) was prepared by adding 2-butanone to this. A coating solution and a film-coated substrate were obtained in the same manner as in Example 1 except that this dispersion was used.

[Comparative example 4]
A suspension was prepared in the same manner as in Example 1, except that 1.3 g of a cationic surfactant (Filanol PA-075F) was added as dispersant A in the mixing step. In the crushing step, the tin oxide powder in the suspension was crushed under the same conditions as in Example 1 except that this suspension was used. However, even if the crushing was continued, the tin oxide powder could not be dispersed in the organic solvent.

[Comparative example 5]
A suspension was prepared in the same manner as in Example 1, except that 1.3 g of Megafac (registered trademark) F-553 manufactured by DIC Corporation was added as dispersant A in the mixing step. In the crushing step, the tin oxide powder in the suspension was crushed under the same conditions as in Example 1 except that this suspension was used. However, even if the crushing was continued, the tin oxide powder could not be dispersed in the organic solvent.

Claims (7)

tin oxide-containing particles;
anionic surfactant,
binder and
A coating liquid comprising an organic solvent,
A coating liquid for forming a conductive film, characterized in that the coating liquid has an average particle diameter of 150 to 400 nm when measured by a dynamic light scattering method. The coating liquid according to claim 1, further comprising silica particles. tin oxide-containing particles;
a titanate coupling agent,
silica particles,
binder and
A coating liquid comprising an organic solvent,
A coating liquid for forming a conductive film, characterized in that the coating liquid has an average particle diameter of 150 to 400 nm when measured by a dynamic light scattering method. The coating liquid according to claim 2 or 3, wherein the silica particles have an average particle diameter of 70 to 400 nm. 4. The coating liquid according to claim 3, further comprising an anionic or cationic surfactant. a mixing step of mixing a tin oxide-containing powder, an anionic surfactant or a titanate coupling agent, and an organic solvent to prepare a suspension;
A crushing step of preparing a dispersion of tin oxide-containing particles by crushing the tin oxide-containing powder in the suspension;
Equipped with an addition step of adding a binder to the dispersion liquid after the crushing step,
A method for producing a coating liquid for forming a conductive film, characterized in that the average particle diameter of the tin oxide particles is adjusted to 200 to 500 nm in the crushing step. A method for manufacturing a substrate with a conductive film, comprising forming a film using the coating liquid according to claim 1 or 3, or the coating liquid obtained by the manufacturing method according to claim 6.