WO2007148747A1

WO2007148747A1 - Conductive particle, conductive powder consisting thereof, process for producing the same, and conductive ink obtained using the conductive powder

Info

Publication number: WO2007148747A1
Application number: PCT/JP2007/062480
Authority: WO
Inventors: Takahiko Sakaue; Koichi Kawaratani
Original assignee: Mitsui Mining & Smelting Co., Ltd.
Priority date: 2006-06-21
Filing date: 2007-06-21
Publication date: 2007-12-27
Also published as: JP5054330B2; TW200809876A; JP2008004332A

Abstract

A conductive powder that has hiding capability while being of bright color and is a filler which in the use as conductive ink or conductive paint, even when the dispersion time is prolonged or when the dispersion operation is repeated, ensures a low deterioration in the surface resistance of coating film obtained. Accordingly, the core material and the conductive layer consist of the common material of TiO2. The TiO2 layer constructing the conductive layer is doped with Nb to thereby not only impart conductivity but also form a Nb diffusion layer, so that there is produced a conductive particle wherein the phenomenon of peel between the core material and the conductive layer is suppressed. From the conductive particle, there is produced a conductive powder.

Description

Specification

Conductive particles, conductive powder composed of the conductive particles, method for producing the same, and conductive ink obtained using the conductive powder

Technical field

The present invention relates to conductive particles, conductive powder composed of the conductive particles, a manufacturing method thereof, and a conductive ink obtained using the conductive powder. In particular, the present invention relates to conductive particles that can reduce the variation in resistance of the obtained conductive film even when the dispersion time when manufacturing conductive ink or the like is increased by using titanium oxide as the core material of the conductive particles.

Background

[0002] In applications that require concealability in the field of plastic film and coating, titanium oxide or the like is used as a filler material when dealing with light colors, and carbon is used when providing conductivity. Black or the like is used as a filler material and is widely used. In particular, conductive inks and conductive paints are expected to expand in the future because they are easy to use because they can form a conductive film only where needed.

[0003] However, when carbon black is used for the purpose of imparting force conductivity, the coating film becomes black, and its use range is limited. However, if titanium oxide, which is a typical concealment material that can provide a bright color, is used as a filler, it will be unsatisfactory in terms of conductivity. Therefore, as a technique for improving the above-mentioned problem, Patent Document 1 discloses an oxide doped with niobium and / or tantalum on a platelet-like or needle-like substrate made of mica, silica, titanium oxide, alumina or the like. A conductive pigment having tin or titanium dioxide as a conductive layer is disclosed. On the other hand, the present inventors have already applied for conductive particles coated with tin oxide using titanium dioxide as a core material.

[0004] Patent Document 1: Japanese Patent Laid-Open No. 10-147729

Disclosure of the invention

Problems to be solved by the invention

[0005] As described above, the conductive particles having concealability and conductivity while maintaining a bright color by providing a conductive layer using tin oxide on the surface of the core material, which is an already filed invention. The coating film obtained by using this film exhibits a surface resistance of 1.0 to 10 ⁶ Ω / muzzle. However, when the conductive particles are used in paints or the like, if they are vigorously stirred in order to obtain a uniform mixed state, or if they are stirred for a long time including repeated stirring, then the conductive film obtained thereafter has a resistance that should be originally obtained. There was a problem that the value increased and the desired effect could not be obtained. Therefore, there has been a demand for conductive powder that can be used in conductive paints and conductive inks that suppress fluctuations in resistance.

Means for solving the problem

[0006] Therefore, the present applicants once again conducted intensive research on conductive particles, and found that the increase in the resistance value was caused by a peeling phenomenon between the core material and the conductive layer. In other words, it is difficult for the conductive layer to be peeled off from the core material, and the conductive layer is formed with a uniform thickness, so that the conductive film obtained from the conductive paint can ensure stable conductivity. Was completed.

[0007] Furthermore, the conductive particles according to the present invention can adjust the resistance value of the conductive film obtained by adjusting the composition of the conductive layer, and is excellent in dispersibility due to the granular shape. It has both a little aggregation! /, Easy to obtain a smooth conductive film, and! /, Characteristics.

[0008] Hereinafter, the conductive particles according to the present invention, the conductive powder composed of the conductive particles, the manufacturing method thereof, and the conductive ink obtained using the conductive powder will be described.

Yes

[0009] Conductive particle according to the present invention: The conductive particle according to the present invention is a granular conductive particle having a conductive layer on the surface of the core material particle, the core material particle is TiO, the particle

2

It features a TiO conductive layer doped with Nb on the surface.

2

[0010] In the conductive particles according to the present invention, the conductive layer preferably has a thickness of 2 nm to 15 nm.

[0011] And, if the Nb content of the conductive layer is 100 wt% of the total TiO content of the conductive particles,

2

And 0 · 05 wt% to 5 wt%.

Conductive powder according to the present invention: The conductive powder according to the present invention is a conductive powder composed of the conductive particles, and the primary particle diameter of the conductive particles is 0.05. It is characterized by being 111 to 1.0 m! [0013] Preferably, the conductive powder has a median diameter D of 3 am or less on a volume basis.

50

Yes

[0014] The electrically conductive powder is also preferably a specific surface area of force Slm ^² / g~22m ² / g.

[0015] The conductive powder has a ratio [(specific surface area of conductive particles) / (specific surface area of core material particles)] of the specific surface area of the core material particles to the specific surface area of the obtained conductive particles. More preferably, it is 0 to 2.0.

[0016] A method for producing a conductive powder according to the present invention: A method for producing a conductive powder according to the present invention includes the following steps A to E.

A: Dispersing TiO powder in water to obtain a TiO suspension.

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B: Titanium salt and niobium salt are added to the TiO suspension and dissolved to prepare a reaction solution.

2

Obtaining step.

C: The reaction solution is prepared in a neutral to alkaline region and coated with an Nb-doped TiO precursor.

2

Obtaining a suspension containing TiO particles.

2

D: Solid suspension is separated from the suspension, and the separated Nb-doped TiO precursor-coated TiO powder is dried.

2 2 and obtaining Nb-doped TiO precursor-coated TiO powder.

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E: Nb-doped TiO precursor-coated TiO powder quasi-solidified by drying

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The process which obtains conductive powder.

[0017] The particle diameter of the TiO powder used in the step A is 0.05 m to 1.0 m;

2

It is also preferable that the TiO concentration in the slag is 20g / L to 500g / L! /.

2

[0018] The titanium salt in the step B is one or more selected from the water-soluble Ti salt titanyl sulfate, titanium chloride, titanium sulfate, and titanium fluoride, and the Ti concentration power wt% to 30wt% It is also preferable.

[0019] The niobium salt in the step B is one or more selected from niobium chloride, niobium fluoride and niobium iodide, and the Nb concentration is 0.02 mol / L to 0.5 mol / L. Is also preferred.

[0020] The pH after adjustment in Step C is 7 to 11; one or two or more selected from Na OH, KOH, Na 2 CO 3 and ammonia are used for pH adjustment.

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It is also preferable. [0021] The firing atmosphere in the step E is also preferably an air atmosphere.

[0022] Conductive ink according to the present invention: The conductive ink according to the present invention uses the conductive powder as a pigment.

Conductive film according to the present invention: The conductive film according to the present invention is obtained using the conductive ink.

The invention's effect

[0024] The conductive particles according to the present invention use TiO as a material common to the core material and the conductive layer.

As a result, the boundary between the core material and the conductive layer becomes unclear, so that the core material and the conductive layer can be prevented from peeling off. Furthermore, since the conductive layer is formed with a uniform thickness, the conductive film obtained from the conductive paint using the conductive particles exhibits stable conductivity. In addition, the surface resistance can be set within the target range by adjusting the Nb doping amount. Further, since the conductive particles are granular, the conductive particles are excellent in dispersibility in the paint, and since there is little aggregation, a smooth conductive film can be obtained. Films and plastics using the conductive powder thus obtained as a filler have a light appearance and are conductive, and the conductivity is set to the optimum range according to the application. It becomes.

BEST MODE FOR CARRYING OUT THE INVENTION

[0025] Form of conductive particles according to the present invention: The conductive particles according to the present invention are granular conductive particles having a conductive layer on a core material particle surface, wherein the core material particles are TiO. So

2 has a TiO conductive layer doped with Nb on the particle surface.

2

[0026] In the present patent application, Nb is used as a doping material for TiO to obtain good conductivity.

2

However, the form of Nb present in the conductive layer is not clear. It is known that Ta oxide, which is an element close to Nb in the periodic table, also exhibits good conductivity in the same way as Nb oxide. Therefore, it is considered that the same effect can be obtained even if Ta is used as a substitute for Nb.

[0027] In the present invention, conductive particles obtained because granular TiO is used as the core material are also provided.

2

Because it is granular and the conductive layer is composed of Nb-doped TiO, the conductive layer and core material

2

One of the features is that the interface with the particles is unclear. The interface between the conductive layer and the core material is unclear because TiO, which is the common material for the core material and the conductive layer, is used. As mentioned above, Nb-doped TiO precursor coated TiO particles are baked in the atmosphere to form conductive particles.

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The TiO precursor is changed to TiO by firing and becomes a sintered state.

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The adhesion between the filler material and the conductive layer becomes strong, and the interface becomes unclear. Then, Nb doping into TiO that forms the conductive layer during this firing proceeds, and this Nb is the core material Ti

2

By diffusing to the O side, a Nb concentration gradient can be created from the conductive layer to the core material layer.

2

Conceivable.

[0028] In the conductive particles according to the present invention, the thickness of the conductive layer is preferably 2 nm to 15 nm. The Nb content of the conductive layer is preferably 100 wt% of the TiO content in the conductive particles.

2

Is preferably 0.05 wt% to 5 wt%. The force that is the thickness of the conductive layer referred to here Since the conductive particles according to the present invention have an unclear interface between the core material and the conductive layer, the mass of the conductive particles and the core material used for the formation thereof TiO mass and doped Nb content

2

Is calculated using the specific surface area.

[0029] The thickness and composition of the conductive layer need only be adjusted according to the electrical characteristics required for the finally formed conductive film. The general required range is the surface resistance value of 1.0 to 10 ^The above range is preferred because it is ⁶ Ω / pocket to 3.0 Χ 10 "^ / pocket, and a more preferable thickness of the conductive layer taking into account manufacturing shading and the like. Is 3 nm ~;! Onm, and the more preferable Nb content is the TiO content of the entire conductive particles.

When 2 is 100 wt%, it is 0.1 wt% to 3. Owt%.

Form of conductive powder according to the present invention: The conductive powder according to the present invention is a conductive powder composed of the conductive particles, and the primary particle diameter of the conductive particles is 0. Ο δ μm ~; 1. O ^ m. If the intended use of the conductive powder according to the present invention is to impart conductivity to organic insulators such as conductive ink, such as paints and plastic films, uniform dispersibility and conductivity It is required to be in a form that can achieve both. Then, considering the required shape of the powder from this required characteristic, it is disclosed in Patent Document 1 for conductivity! /, And such flaky flakes are preferred! / . However, flakes lack uniform dispersibility, and applying strong dispersion treatment with strong stirring or long-time stirring causes peeling of the conductive layer or destruction of the flakes themselves, resulting in difficulty in process design to obtain the desired characteristics. It will become. [0031] In order to improve dispersibility, the shape of the particles is granular, and specifically, those having an isotropic shape such as a spherical shape or a pseudo-spherical shape are preferred. On the other hand, if the content is the same for inks or paints in which scale-like or needle-like particles having a non-particulate shape are dispersed, the viscosity will increase, and the uniformity of the coating will not be obtained. It will end up. From this point of view, it is preferable that the conductive particles have a granular shape and the primary particle diameter is larger than 0.05 m. When the primary particle diameter of the conductive particles exceeds 1.0 m, the surface smoothness of the conductive film is inferior regardless of the shape of the particles, and at the same time, the gaps between the particles become large and good concealment is achieved. In order to obtain the properties, even if the filling rate is increased, the coating thickness must be taken into consideration. Further, the primary particle diameter of the conductive particles is more preferably 0.1 111 to 0.5 μm.

[0032] The conductive powder has a median diameter D of 3 m or less on a volume basis.

50

preferable. As mentioned above, the effect of particle size on the viscosity of inks and paints cannot be ignored. In other words, it is necessary to consider the distribution of particle diameters not only in the particle diameter range. According to this point of view, the median diameter D is more preferably 0 · 2 ^ 111-1.5 111 on a volume basis, particularly for conductive ink applications that require strong control of coating thickness.

50

[0033] The electrically conductive powder is preferably a specific surface area force ^{^{S lm 2 / g~22m 2 / g}} . TiO used as the core material is originally a material with a large specific surface area.

2

In forming a conductive layer by the manufacturing method in this case, a liquid phase reaction is employed. That is, the characteristics of the conductive particles obtained are influenced by the particle size and surface condition of the TiO particles used as the core material.

2

The sound is greatly affected. Thus, since the conductive particles and conductive powder according to the present invention exhibit stable characteristics is the fact preferably has a specific surface area of lm ^² / g~22m ² / g. The more preferable range of the specific surface area of 5 m ² / g to;! A 17m ² / g, further preferably /, range is ^{^{7m 2 / g~ 15m 2 / g}} .

[0034] The conductive powder has a ratio [(specific surface area of conductive particles) / (specific surface area of core material particles)] of the specific surface area of the core material particles to the specific surface area of the obtained conductive particles. More preferably, it is 0 to 2.0. As described above, the liquid phase reaction is employed in forming the conductive layer by the manufacturing method of the present invention. Therefore, it is necessary to keep the surface as smooth as possible in order to exhibit the force conductivity that has an uneven shape when the surface is observed microscopically. There is a point. Therefore, if the ratio of the specific surface area of the core material particles to the specific surface area of the obtained conductive particles [(specific surface area of conductive particles) / (specific surface area of core material particles)] is 1.0 to 2.0 Stable conductivity can be ensured.

[0035] Manufacturing method of conductive powder according to the present invention: The method for manufacturing a conductive powder according to the present invention includes the following steps A to E.

[0036] Step A is a step in which TiO powder is dispersed in water to obtain a TiO suspension.

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The purpose is to release and uniformly disperse. And the TiO powder used here

2 Particle size is 0 · 05 μ ΐη to 1. Ο μ ΐη, and TiO concentration in suspension is 20 g / L to 500 g / L

2

It is preferable that The mass of the conductive layer to be formed is not small compared to the mass of the core material, but considering that the conductive layer is formed on the outer layer of the core material having a large specific surface area, it is necessary to strictly consider it as an increase in particle size It can be considered that the particle size of the core material prepared here is almost the same as the particle size of the conductive particles. Therefore, the particle diameter of the core material can be made to substantially match the particle diameter of the target conductive particles. The range of the particle diameter is determined in consideration of the viscosity of the ink obtained by using the above-described conductive powder and the concealability of the coating film. In addition, the TiO concentration (slurry concentration) in the suspension mainly depends on the productivity and conductive particles.

2

It is determined in consideration of the characteristics. For example, if the slurry concentration is too high, the particles tend to aggregate and the dispersibility deteriorates. If the slurry concentration is too low, the adhesion between the core material and the conductive layer tends to decrease. From this viewpoint, the upper limit of the slurry concentration is preferably 500 g / L, and the more preferable upper limit concentration is 300 g / L. The lower limit of 20 g / L is also the slurry concentration that can maintain industrial productivity.

[0037] In step B, the titanium salt and niobium salt are added to the TiO suspension obtained in step A and dissolved.

2

This is a step of preparing a reaction solution, and is a step of setting the film thickness and Nb doping amount of the conductive film formed on the surface of the core material. Specifically, the titanium salt used is a water-soluble Ti salt. One or more selected from titanyl sulfate, titanium chloride, titanium sulfate, titanium fluoride, etc. If the Ti concentration is 1 wt% to 30 wt% good. Since the addition amount of the titanium salt is set with respect to the slurry concentration, it is preferable to control it with wt%. Any titanium salt may be used as long as it is water-soluble, and titanyl sulfate, titanium chloride, titanium sulfate, titanium fluoride, etc. can be used. And Ti concentration is the core material The concentration is set so that the thickness of the conductive layer formed on the surface is optimal. That is, a high concentration may be used when forming a thick conductive layer, and a low concentration may be used when forming a thin conductive layer.

[0038] The niobium salt is one or more selected from niobium chloride, niobium fluoride, niobium iodide and the like, and the Nb concentration may be 0.02 mol / L to 0.5 mol / L. The niobium salt used here may be any niobium salt as long as it is water-soluble, as can titanium salts, such as niobium chloride, niobium fluoride, and niobium iodide. The Nb concentration is set to a concentration that optimizes the amount of doping to the conductive layer formed on the surface of the core material. That is, when the amount of doping is increased, the concentration is high, and when the amount of doping is decreased, the concentration is low.

[0039] In step C, the reaction liquid prepared in step B is adjusted to a neutral to alkaline region to precipitate Nb-doped TiO precursor (mainly hydroxide), and Nb-doped TiO precursor coating TiO

This is a process to obtain a suspension containing 2 2 2 particles, and the uniform Nb-doped TiO

2 2 This is the process of forming the precursor film. Specifically, in order to make the pH after preparation 7 to; 11 neutral to alkaline region, strong alcohol such as NaOH, KOH, Na 2 CO or ammonia

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One or more selected from the above may be used for pH adjustment. Since this step is a reaction in the form of a suspension, it is better to add a stirring operation.

[0040] In this step C, attention is paid to the time required to complete the addition of the alkali. Specifically, it is preferably 10 minutes to 90 minutes. In the example described later, it takes 70 minutes. For example, as a simple example, the situation in which Step B and Step C are simultaneously progressed, that is, if titanium salt, niobium salt and alkali are simultaneously added to the suspension in which the core material is dispersed, it will be in the reaction solution. Unevenness in the contact state between titanium salt and niobium salt and alkali, resulting in a uniform TiO precursor shape

2

It becomes difficult to complete.

[0041] Then, after adding an alkali to the suspension in which the core material is dispersed, and adding a titanium salt or niobium salt, the TiO precursor, which is a conductive layer formed on the core material surface, is in a porous state.

2

When the conductive powder is used for the conductive paint, it becomes inferior in conductivity.

[0042] In Step D, the suspension obtained in Step C is subjected to solid-liquid separation, and the separated Nb-doped TiO precursor core is separated. The TiO powder is dried to obtain Nb-doped TiO precursor-coated TiO powder.

2 2 2

Purification, filtration and drying may be performed.

[0043] In step E, the Nb-doped TiO precursor-coated TiO powder cake obtained in step D was crushed.

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This is a step of later firing in an air atmosphere to obtain conductive powder, and a step of using the Nb doped TiO precursor layer formed in Step B as an oxide. In this process, Nb is added to TiO

2 2 and will exhibit the desired characteristics. Conventional crushing equipment such as a force mill can be used to crush the powder. And the force which is the atmosphere at the time of baking In this invention, it is set as air atmosphere. This is because the main component of the TiO precursor layer is titanium hydroxide.

2

This is because if the dehydration reaction proceeds, it is considered that a sufficient effect is exhibited.

[0044] Form of the conductive ink according to the present invention: The conductive ink according to the present invention uses the conductive powder as a pigment, and the viscosity is optimally prepared according to the application. . Since the conductive ink obtained here uses a granular conductive powder, the solid content of the conductive particles as the ink is higher than when a scaly or acicular conductive powder is used. . Therefore, even if the conductive film thickness to be formed is the same, the amount of ink to be used is reduced, and the influence on the environment due to a small amount of organic solvent is reduced. The use of the conductive powder according to the present invention is not limited to the conductive ink, but can also be used for the purpose of imparting conductivity to the above-described conductive paint and plastic.

[0045] Examples and comparative examples are shown below, but the present invention should not be construed as being limited to these! /. Regarding the methods for preparing the conductive powders and conductive inks prepared in the examples and comparative examples, the forces described individually in the examples and comparative examples described below are shown in Table 1. The result of surface resistance data is shown. Figure 1 is a graph of this. In Table 1, a conductive film formed using the conductive powder formed according to the present invention is listed as Example 1, and for comparison, a conductive powder having a conductive layer formed using tin oxide is shown. The conductive film formed using this was listed as Comparative Example 1.

[0046] [Table 1] Surface resistance (Ω / port)

Dispersion time (Hr)

Example

Comparative example Example

[0048] [Preparation of conductive powder]

1. Adjustment of chemicals used

Titanium salt solution: Use titanyl sulfate to adjust the Ti content to 5 wt%

Niobium salt solution: Prepare by dissolving 3 g of niobium pentachloride in 100 ml of concentrated hydrochloric acid.

pH adjustment solution: Sodium hydroxide 25wt% aqueous solution

[0049] 2. Formation of conductive layer

Pure water 1. Add 100 g of TiO powder with a primary particle size of 0.115 111 to 5 L and suspend the TiO powder dispersed.

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A turbid liquid was obtained. To this suspension, 400 g of a titanium salt solution and 20 ml of a niobium salt solution were added to obtain a reaction solution. The reaction solution thus obtained was heated to 60 ° C., and 350 mL of pH adjusting solution was added over 70 minutes. The suspension obtained here is further stirred for 30 minutes and then washed by the repulping method. Finally, the solid is separated by suction filtration using a Nutsche, dried, and quasi-solidified powder. Got.

[0050] 3. Formation of conductive powder

Next, the dried and quasi-solidified powder was pulverized using a force mill and fired in an air atmosphere at 700 ° C for 1 hour to form a TiO conductive layer in which TiO powder was doped with TiO powder.

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Powder was obtained.

[0051] 4. Evaluation of conductive powder

Particle size: 0.15 111 (SEM observation image power at a magnification of 60,000 times, average of 50 arbitrarily selected particle sizes)

D: 0.6〃111 (200111 Sampnore container)

50

After mixing 10 mL of sodium oxametaphosphate, 90 mL of pure water was added and dispersed for 10 minutes using an ultrasonic dispersing machine (US-300T manufactured by Nippon Seiki Co., Ltd.) to prepare a sample suspension. Using the sample suspension LA-920 manufactured by Horiba, Ltd., the particle size when the cumulative volume determined by the laser diffraction scattering method reached 50%)

Specific surface area: Core material: 10.0 m ² / g, conductive powder: 11.6 m ² / g (measured by BET method) L value: 96.9 (color difference measuring device (CM- 3500d, manufactured by Koni Minolta Co., Ltd.) ) To measure color tone) [0052] Next, the thickness of the conductive layer was calculated by the following procedure.

a) Obtain the mass of the coating part from the mass of the obtained conductive powder and the mass of the core material used.b) Divide the coating mass by the density of titanium oxide, and then harm the surface area of the core material obtained above. Thus, the coat thickness (conductive layer thickness: nm) is obtained.

c) Obtain the Nb doping amount (%) from the analytical value of Nb contained in the conductive powder.

As a result, the conductive layer thickness is about 8 nm, and the TiO content of the entire conductive particles is 100 wt%.

2

On the other hand, the mass thickness of the conductor layer is 25 wt%, and the Nb doping amount is 0.2 wt% when the total TiO content of the conductive particles is 100 wt%, and when the TiO content of the conductive layer is 100 wt%. 0. 8

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Wt%.

[Preparation of conductive ink]

1. Conductive powder 7.41g and acrylic resin (Dianar LR-167, manufactured by Mitsubishi Rayon Co., Ltd.) 6.41g and toluene-butanol mixture as solvent to form conductive film in a 50cc container The mixture was mixed so that the content of the conductive particles later became 70%.

[0054] 2. Next, glass beads are added to the mixture, and dispersion treatment is performed for 1 hour, 2 hours, 3 hours, 4 hours, and 5 hours using a paint shaker. Ink 5 was obtained.

[0055] [Formation of coating film]

Using the conductive inks 1 to 5, the coating film was formed on a PET film using a bar coater (# 10).

[0056] [Evaluation results]

The coating film was dried in a hot air circulation oven set at 80 ° C. for 30 minutes, and then surface resistance was evaluated using Hiresta IP manufactured by Mitsubishi Chemical Corporation. The results are shown in Table 1. The surface resistance value of the conductive film formed using conductive ink 5 with a dispersion time of 5 hours is only 33 times the surface resistance value of the conductive film formed using conductive ink 1 with a dispersion time of 1 hour. The effect of increasing the dispersion time was small and good.

[0057] [Preparation of conductive powder] 1. Formation of conductive layer

Suspension in which 900 g of TiO powder similar to that used in Example 1 was added to 5 L of pure water and TiO powder was dispersed

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A liquid was obtained. To this suspension, 930 g of sodium stannate trihydrate was added, and pure water was added so that the total liquid volume became 8 L. The reaction solution thus obtained was heated to 70 ° C. and maintained for 60 minutes, and 1.6 L of 20% sulfuric acid was added over 90 minutes. The suspension obtained here is stirred for another 30 minutes and then maintained and washed by the repulp method. Finally, it is filtered by suction using a Nutsche to separate and dry the solid, and SnO is added to TiO. A coated powder was obtained.

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[0058] 2. Formation of conductive powder

Next, the dried and pseudo-solidified powder was pulverized using a force mill, and baked for 1 hour in a reducing atmosphere (2% H — N) at 700 ° C.

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[0059] 3. Evaluation of conductive powder

For the following items, the same evaluation method as in Example 1 was used.

Particle size: 0 · Ι δ β ϊη

D: 0. δ ^ ιη

50

Specific surface area: Core material is 10.0 m ² / g, conductive powder is 25. lmVg

L value: 85.3

[0060] Next, the thickness of the conductive layer was determined by the following calculation.

a) Determine the mass thickness of the conductive layer from the mass of the obtained conductive powder and the amount of TiO used for the core material.

2

Ask.

b) Divide the coat mass by the density of tin oxide, and further determine the coat thickness (conductive layer thickness: nm) by damaging the surface area of the core material obtained above.

c) Convert the Sn quality in the conductive powder into SnO mass, and the SnO coat mass thickness (%

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)

As a result, the conductive layer thickness is about 8 nm, and the mass thickness of the conductor layer is derived in terms of SnO.

2 The total amount of Ti was 35wt% with respect to 100wt% of Ti particles.

2

[0061] [Preparation of conductive ink]

Dispersion treatment was performed in the same manner as in Example 1 to obtain conductive ink 1 ′ to conductive ink 5 ′. [0062] [Formation of coating film]

The same operation as in Example 1 was performed.

[0063] [Evaluation results]

The surface resistance was evaluated in the same manner as in Example 1. The results are shown in Fig. 1 and Table 1. The surface resistance of the conductive film formed using Ink 5 'with a dispersion time of 5 hours increased to 120, 000 times the surface resistance of the conductive film formed using Ink 1' with a dispersion time of 1 hour. And about 5 times that of the conductive film formed using the ink 5 obtained in the example.

Yes

[0064] [Contrast between Example and Comparative Example]

With reference to Table 1, the data obtained in the examples and comparative examples are referred to, and the examples and comparative examples are compared.

[0065] As can be seen from Table 1, the conductive ink obtained using the conductive powder composed of the conductive particles of Example 1 according to the present invention has a dispersion time as compared with Comparative Example 1. As a result, the conductivity was stable!

Industrial applicability

[0066] Conductive ink, conductive paint or conductive plastic using conductive powder, which is an aggregate of conductive particles according to the present invention, as a filler is light-colored and has concealing properties. , Having stable conductivity.

Brief Description of Drawings

FIG. 1 is a diagram showing the surface resistance of a conductive film obtained by changing the dispersion time of conductive ink.

Claims

The scope of the claims

[1] Granular conductive particles having a conductive layer on the surface of the core material particles,

The core material particle is TiO, and a TiO conductive layer doped with Nb is provided on the particle surface.

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A granular conductive particle characterized by the above.

[2] The conductive particle according to [1], wherein the thickness of the conductive layer is 2 nm to 15 nm.

[3] The Nb content of the conductive layer is 0.0 when the TiO content of the entire conductive particles is 100 wt%.

2

The conductive particles according to claim 1 or 2, wherein the conductive particles are 5 wt% to 5 wt%.

[4] A conductive powder composed of the conductive particles according to any one of claims 1 to 3 of claim 1;

Conductive powder characterized in that the primary particle size of the conductive particles is 0 · Οδ, ΐη-Ι.0 m.

5. The conductive powder according to claim 4, wherein the median diameter D is 3 in or less on a volume basis.

50

[6] The specific surface area force Slm ^² / g~22m ² / g and electrically conductive powder according to claim 4 or claim 5.

[7] The ratio of the specific surface area of the core material particles to the specific surface area of the obtained conductive particles [(specific surface area of the conductive particles) / (specific surface area of the core material particles)] is 1.0 to 2.0 7. The conductive powder according to any one of claims 4 to 6.

[8] A method for producing conductive powder, comprising:

The method for producing a conductive powder according to any one of claims 4 to 7, further comprising the following steps A to E.

A: Dispersing TiO powder in water to obtain a TiO suspension.

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2

Obtaining step.

C: The reaction solution is prepared in a neutral to alkaline region to prepare an Nb-doped TiO precursor coating.

2 G A step of obtaining a suspension containing TiO particles.

2

2 2 and obtaining Nb-doped TiO precursor-coated TiO powder.

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E: Nb-doped TiO precursor-coated TiO powder quasi-solidified by drying

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The process which obtains conductive powder.

[9] The particle diameter of the TiO powder used in the step A is 0.05 m to 1.0 m,

2

9. The method for producing a conductive powder according to claim 8, wherein the TiO concentration power is ¾0 g / L to 500 g / L.

2

[10] The titanium salt in step B is one or more selected from the water-soluble Ti salt titanyl sulfate, titanium chloride, titanium sulfate, and titanium fluoride, and the Ti concentration is 1 wt% to 30 wt%. The method for producing a conductive powder according to claim 8 or 9.

[11] The niobium salt in step B is one or more selected from niobium chloride, niobium fluoride and niobium iodide, and the Nb concentration is from 0.02 mol / L to 0.5 mol / L. Item 11. A method for producing a conductive powder according to any one of Items 8 to 10.

[12] The pH after preparation in Step C is 7 to 11; the neutral to alkaline region of 11; one or more selected from NaOH, KOH, Na 2 CO 3 and ammonia are used for pH adjustment.

twenty three

A method for producing a conductive powder according to any one of claims 8 to 11.

[13] The process for producing conductive powder according to any one of claims 8 to 12, wherein the firing atmosphere in the step E is an air atmosphere.

[14] A conductive lifetime ink obtained by using the conductive powder according to any one of claims 4 to 7 as a pigment.

[15] A conductive film obtained using the conductive ink according to claim 14.