JP4793537B2 - Visible light transmission type particle-dispersed conductor, conductive particles, visible light transmission type conductive article, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a visible light transmissive particle-dispersed conductor using conductive particles containing tungsten oxide and / or composite tungsten oxide, and a visible light transmissive type formed from the visible light transmissive particle-dispersed conductor. The present invention relates to a conductive article, conductive particles used in the visible light transmissive particle-dispersed conductor and the visible light transmissive conductive article, and a manufacturing method thereof.

At present, transparent conductive films are used for various display elements, plasma light emitting display elements, transparent electrodes such as solar cells, infrared absorbing reflection films, antifogging films, electromagnetic shielding films, and the like.
In recent years, the demand for transparent electrodes has increased due to the development of various display elements. As the transparent electrode, ITO (Indium-Tin-Oxide) in which indium oxide is doped with several mol% of tin is mainly used because it has many free electrons in the material and high conductivity (Patent Literature). 1, 2). In ₂ O _3, which is the base material of ITO, is an oxide semiconductor, and is a transparent conductive material that exhibits conductivity when carrier electrons are supplied from oxygen defects contained in the crystal. It is believed that when Sn is added to this In ₂ O ₃ , carrier electrons are greatly increased and high conductivity is exhibited.

  By the way, recent various display devices tend to reduce the cost, and in order to obtain a high-quality display element free from display defects, it is hoped that the performance of the transparent electrode, in particular, the reduction of the sheet resistance value and the improvement of the visible light transmittance will be expected. In addition, cost reduction of the transparent electrode itself is a very important issue. Improvements in physical properties and cost reduction of transparent conductive films have been promoted by improving ITO film formation technology and sputtering targets, but there is a limit to reducing the cost of ITO and responding to a wider range of recent needs. Has become difficult.

  Moreover, as a particle-dispersed transparent conductive film, an aqueous solution (A) containing silver salt and palladium salt and an aqueous solution (B) containing citrate ion and ferrous ion are substantially free of oxygen. A fine particle film formed by precipitating Ag-Pd fine particles by mixing in an atmosphere and applying a coating solution containing the Ag-Pd fine particles in water and / or an organic solvent on a substrate (Patent Document 3) In addition, ITO fine particles having an average primary particle diameter of 10 to 60 nm form secondary particles having an average secondary particle diameter of 120 to 200 nm, and the transparent is formed using an ink composition in which the secondary particles are dispersed. A conductive film (Patent Document 4) is known.

In Patent Document 5, a meta-type ammonium tungstate and various water-soluble metal salts are used as raw materials, and the dried product of the mixed aqueous solution is treated with an inert gas (addition amount: about 50 vol.) At a heating temperature of about 300 to 700 ° C. % or more) or steam (amount; _M X _WO 3 (M element by supplying about 15 vol% or less) of hydrogen gas was added; alkali, alkaline earth, metal elements such as rare earth, 0 <x <1) And a method for producing various tungsten bronze-coated composites by carrying out similar operations on a support. However, the tungsten bronze is considered as a solid material used for an electrode catalyst such as a fuel cell or an electrochromic material, and no consideration is given to transparent conductivity.

JP 2003-249125 A JP 2004026655 A JP 2000-90737 A JP 2001-279137 A JP-A-8-73223

The ITO conductive films described in Patent Documents 1 and 2 are expensive because indium is used, and an inexpensive transparent conductive thin film is industrially desired.
Further, the noble metal particles described in Patent Document 3 and the ITO particles described in Patent Document 4 can be formed by a coating method, so that a large-scale apparatus is not required and the film formation cost can be reduced. Is expensive and lacks versatility.

An object of the present invention is to provide a visible light transmissive particle-dispersed conductor that is excellent in visible light transmittance and conductivity and inexpensive.
Another object of the present invention is to provide conductive particles used in the above-described visible light transmission type particle-dispersed conductor.
Still another object of the present invention is to provide a visible light transmissive conductive article using a visible light transmissive particle dispersed conductor which is excellent in visible light transmittance and conductivity and is inexpensive.
Still another object of the present invention is to provide a method for producing conductive particles that can produce conductive particles for obtaining a visible light transmissive particle-dispersed conductor that is excellent in visible light transmittance and conductivity and that is inexpensive, by a simple method. There is to do.

  Tungsten trioxide is a wide bandgap oxide, hardly absorbs light in the visible light region, and has no free electrons (conduction electrons) in its structure. However, it is known that a small amount of oxygen is reduced from tungsten trioxide or a so-called tungsten bronze in which a positive element such as Na is added to tungsten trioxide, free electrons are generated and conductivity is exhibited. A small amount of oxygen is reduced from tungsten trioxide, and tungsten bronze with a positive element added to tungsten trioxide is recognized to absorb light in the visible light region. It is not applied as a material.

  The inventors of the present invention have a small amount of oxygen reduced from the above-mentioned tungsten trioxide and tungsten bronzes obtained by adding a positive element to tungsten trioxide strongly absorb light having a wavelength of about 800 nm or more, but have a wavelength of 380 nm to 780 nm. Light absorption in the wavelength region (visible light region) perceived by people is weak compared to the former (light with a wavelength of about 800 nm or more), so a visible light transmission type transparent conductor film can be formed It was noted that.

  And since the tungsten trioxide has a wide band gap, the present inventors utilize the skeletal structure of tungsten trioxide, reduce the oxygen content of this tungsten trioxide, or add cations to conduct Electrons (free electrons) are generated, and the particle diameter and shape of the tungsten oxide particles and composite tungsten oxide particles are controlled to produce particles having conductivity while transmitting light in the visible light region. As a result, a visible light transmission type particle dispersed conductor was obtained.

That is, the first invention of the present invention is
Tungsten oxide magnetic phase represented by the general formula WyOz (W is tungsten, O is oxygen, z / y = 2.72 ), or / and the general formula MxWyOz (where the M element is Cs, Rb, One or more elements selected from K, Na, Ba, In, and Tl, W is tungsten, O is oxygen, 0.33 ≦ x / y ≦ 0.55, z / y = 3 ) A composite tungsten oxide having a hexagonal tungsten bronze structure, a particle diameter of 1 nm or more, visible light permeability, and the particles were measured under a pressure of 9.8 MPa. A visible light transmissive particle-dispersed conductor characterized by being a plurality of aggregates of conductive particles having a dust resistance value of 1.0 Ω · cm or less.

The second invention of the present invention is:
2. The visible light transmissive particle-dispersed conductor according to the first invention, wherein the conductive particles have one or more of a granular shape, a needle shape, or a plate shape.

The third invention of the present invention is:
The conductive particles include needle-like crystals or are all needle-like crystals, and the ratio of the major axis to the minor axis (major axis / minor axis) in the acicular crystal is 5 or more, and The visible light transmitting particle-dispersed conductor according to the first or second invention, wherein the length of the major axis is 5 nm or more and 10,000 μm or less.

The fourth invention of the present invention is:
The conductive particles include a plate-like crystal or are all plate-like crystals, the plate-like crystal has a thickness of 1 nm or more and 100 μm or less, and a pair of plate-like surfaces in the plate-like crystal. The maximum value of the angular length is 5 nm or more and 500 μm or less, and the ratio of the maximum value of the diagonal length and the thickness of the plate crystal (maximum value of the diagonal length / thickness) is 5 or more. A visible light transmissive particle-dispersed conductor according to the first or second invention, characterized in that

The fifth invention of the present invention is:
The visible light transmitting particle-dispersed conductor according to any one of the first to fourth inventions, wherein the visible light transmitting particle-dispersed conductor is a film.

The sixth invention of the present invention is:
The visible light transmissive particle-dispersed conductor contains a binder .
The visible light transmissive particle-dispersed conductor according to any one of the inventions .

The seventh invention of the present invention is
The visible light transmission type particle-dispersed conductor according to the sixth aspect, wherein the binder is a transparent resin or a transparent dielectric.

The eighth invention of the present invention is:
The tungsten oxide magnetic phase represented by the general formula WyOz (W is tungsten, O is oxygen, z / y = 2.72 ), or / and the general formula MxWyOz (where the M element is Cs, Rb, One or more elements selected from K, Na, Ba, In, and Tl, W is tungsten, O is oxygen, 0.33 ≦ x / y ≦ 0.55, z / y = 3 ) A composite tungsten oxide having a hexagonal tungsten bronze structure, a particle diameter of 1 nm or more, visible light permeability, and the particles were measured under a pressure of 9.8 MPa. The conductive particles are characterized by having a dust resistance value of 1.0 Ω · cm or less.

The ninth invention of the present invention is:
A visible light transmission type conductive article, wherein the visible light transmission type particle dispersed conductor according to any one of the first to seventh inventions is formed on a substrate.

The tenth aspect of the present invention is:
The tungsten oxide magnetic phase represented by the general formula WyOz (W is tungsten, O is oxygen, z / y = 2.72 ), or / and the general formula MxWyOz (where the M element is Cs, Rb, One or more elements selected from K, Na, Ba, In, and Tl, W is tungsten, O is oxygen, 0.33 ≦ x / y ≦ 0.55, z / y = 3 ) A method for producing conductive particles comprising a composite tungsten oxide having a hexagonal tungsten bronze structure as a crystal structure,
A method for producing conductive particles, wherein the conductive particles are produced by heat-treating a tungsten compound as a raw material of the conductive particles in a reducing gas and / or inert gas atmosphere.

The eleventh aspect of the present invention is
In the method for producing conductive particles according to the tenth invention, the heat treatment is performed by heat-treating a tungsten compound as a raw material of the conductive particles at 100 ° C. or higher and 850 ° C. or lower in a reducing gas atmosphere. is there.

The twelfth aspect of the present invention is
In the heat treatment, a tungsten compound as a raw material of the conductive particles is heat-treated at 100 ° C. or higher and 850 ° C. or lower in a reducing gas atmosphere , and then at a temperature of 550 ° C. or higher and 1200 ° C. or lower in an inert gas atmosphere. It is a manufacturing method of the electroconductive particle as described in 10th invention characterized by heat-processing.

The thirteenth aspect of the present invention is
After the tungsten compound as the raw material for the conductive particles dissolves tungsten trioxide, tungsten oxide, tungsten oxide hydrate, tungsten hexachloride, ammonium tungstate, tungstic acid, and tungsten hexachloride in alcohol. Tungsten oxide hydrate obtained by drying, tungsten oxide hydrate obtained by dissolving tungsten hexachloride in alcohol and then adding water to form a precipitate and drying the precipitate The method for producing conductive particles according to the tenth or twelfth invention, wherein the method is one or more selected from a tungsten compound obtained by drying an ammonium acid aqueous solution and metallic tungsten.

The fourteenth invention of the present invention is
A tungsten compound as a raw material for the conductive particles according to the thirteenth invention, and an M element (provided that the M element is one or more selected from Cs, Rb, K, Na, Ba, In, and Tl) A powder obtained by mixing a solution or dispersion of the tungsten compound and a solution or dispersion of the compound containing the element M and then drying the mixture. The method for producing conductive particles according to any one of the tenth to thirteenth inventions, wherein one or more selected from the above are used as a tungsten compound as a raw material for the conductive particles.

The visible light transmission type particle-dispersed conductor according to the first to seventh aspects of the present invention is a conductive particle in which the amount of oxygen in tungsten trioxide is reduced to generate conduction electrons, and / or a cation to tungsten trioxide. Since the conductive particles containing the composite tungsten oxide that has generated conduction electrons by adding the conductive particles are included, the light transmission in the visible light region is excellent and the conductivity is excellent.
Since the conductive fine particles according to the eighth invention are excellent in light transmission in the visible light region and excellent in conductivity, they are suitable for the visible light transmission type particle dispersed conductors according to the first to tenth inventions. Can be used.
The visible light transmissive particle-dispersed conductive article according to the ninth aspect of the invention is excellent in light transmittance in the visible light region and excellent in conductivity.
According to the method for producing conductive fine particles according to the tenth to fourteenth inventions, conductive particles are obtained by heat-treating a tungsten compound as a raw material of the conductive particles in a reducing gas and / or inert gas atmosphere. Therefore, the conductive particles can be manufactured at a low cost by a simple method.

The best mode for carrying out the present invention will be described below with reference to the drawings.
The visible light transmissive particle-dispersed conductor according to the present invention is a tungsten oxide represented by the general formula W _y O _z (W is tungsten, O is oxygen, 2.2 ≦ z / y ≦ 2.999). Or / and general formula M _x W _y O _z (where M element is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh) Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te , Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, one or more elements, W is tungsten, O is oxygen, 0.001 ≦ x / y ≦ 1.1, 2.2 ≦ z / y ≦ 3.0) A plurality of conductive particles having a particle diameter of 1 nm or more, visible light permeability, and a dust resistance value of 1.0 Ω · cm or less when the particles are measured under a pressure of 9.8 MPa are gathered. Thus, they are in contact with each other to form a conductor.
Further, when the conductive particles include needle-like crystals or all are needle-like crystals, the ratio of the major axis to the minor axis (major axis / minor axis) in the acicular crystal is 5 or more. The length of the major axis is 5 nm or more and 10,000 μm. In addition, when the conductive particles include plate crystals or all are plate crystals, the thickness of the plate crystals is 1 nm or more and 100 μm or less, and the plate-like surfaces of the plate crystals are The maximum value of the diagonal length is 5 nm or more and 500 μm or less, and the ratio (maximum value of the diagonal length / thickness) between the maximum value of the diagonal length and the thickness of the plate crystal is 5 or more. Is.
Hereinafter, the visible light transmissive particle-dispersed conductor and the conductive particles used therein will be described in detail.

1. Conductive Particles Generally, tungsten trioxide (WO ₃ ) is excellent in visible light transmission, but is not effective as a conductive material because there are no effective conduction electrons (free electrons). Here, it is known that free electrons are generated in WO ₃ by reducing the ratio of oxygen to tungsten in WO ₃ from ₃ , but the present inventor has proposed that the composition range of tungsten and oxygen is as follows. It was found that there is a specific effective range as a conductive material in a specific part.

In the tungsten oxide, the composition range of the tungsten and oxygen is such that the composition ratio of oxygen to tungsten is less than 3, and further, when the conductive particles are described as W _y O _z , 2.2 ≦ z It is preferable that /y≦2.999. If this z / y value is 2.2 or more, it is possible to avoid the appearance of a crystal phase of WO ₂ that is not intended in the conductive material, and to improve the chemical stability as a material. Therefore, it can be applied as an effective conductive material. On the other hand, if the value of z / y is 2.999 or less, a required amount of free electrons is generated and a conductive material is obtained.

In the composite tungsten oxide, the to the three-tungsten oxide (WO _3), the element M (where, M element, H, the He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, Adding one or more elements selected from S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I) Conducted electrons (free electrons) are generated in WO ₃ and become effective as a conductive material.

That is, this conductive material has the general formula M _x W _y O _z (where M element is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co , Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br , Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, one or more elements, W is tungsten, O is oxygen, 0.001 ≦ x / It is necessary to be a composite tungsten oxide represented by y ≦ 1.1, 2.2 ≦ z / y ≦ 3.0). Further, from the viewpoint of stability, the M element is an alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, More preferably, the element is one or more elements selected from Re, Be, Hf, Os, Bi, and I.

  Further, from the viewpoint of improving optical properties and weather resistance, it is more preferable that the M element belongs to an alkaline earth metal element, a transition metal element, a group 4B element, and a group 5B element.

As for the amount of oxygen and the amount of M element added, when M _x W _y O _z (where M element is M element, W is tungsten, and O is oxygen), 0.001 ≦ x / y ≦ A material satisfying the relationship of 1.1, 2.2 ≦ z / y ≦ 3.0 is desirable. As the amount of M element added increases, the amount of conduction electrons supplied tends to increase. When z / y = 3, the optimum addition amount of the additive element M is obtained. This is because M _x W _y O _z has a so-called tungsten bronze crystal structure as described above. For example, the amount of M element added to 1 mol of tungsten is preferably up to about 0.33 mol in the case of a hexagonal tungsten bronze crystal structure, and in the case of a tetragonal tungsten bronze crystal structure. In the case of the crystal structure of the cubic tungsten bronze, it is preferably up to about 1 mol. However, since the above crystal structure can take various forms, the amount of additive element M added is not necessarily limited to the above-described additive amount.

Next, in the composite tungsten oxide represented by M _x W _y O _z , the value of z / y indicating the control of the oxygen amount will be described. The z / y value, in addition to conduction electrons in the same range as tungsten oxide W _y O _z of the above (2.2 ≦ z / y ≦ 2.999 ) ( free electrons) are expressed, z Even when /y=3.0, since conduction electrons are supplied by the amount of addition of the M element described above, 2.2 ≦ z / y ≦ 3.0 is preferable, and 2.72 ≦ z / y ≦ is more preferable. 3.0.

  Moreover, it is preferable that the electroconductive particle of this embodiment is a particle | grain size of 1 nm or more. Since these conductive particles absorb a large amount of light in the vicinity of a wavelength of 1000 nm, the transmission color tone often changes from blue to green. Further, the size of the particles can be selected according to the purpose of use. First, when used for an application that maintains transparency, it preferably has a particle size of 800 nm or less. This is because particles having a particle diameter smaller than 800 nm do not completely block light due to scattering, and can maintain visibility in the visible light region and at the same time efficiently maintain transparency. In particular, when importance is attached to transparency in the visible light region, it is preferable to further consider scattering by particles.

  When importance is attached to the reduction of scattering by the particles, the particle diameter is 200 nm or less, preferably 100 nm or less. The reason for this is that if the particle size of the particles is small, the scattering of light in the visible light region having a wavelength of 380 nm to 780 nm due to geometric scattering or Mie scattering is reduced, so that the film becomes transparent like a frosted glass. This is because it is possible to avoid the loss of sex. That is, when the particle diameter is 200 nm or less, the geometric scattering or Mie scattering is reduced and a Rayleigh scattering region is obtained. This is because in this Rayleigh scattering region, the scattered light decreases in inverse proportion to the sixth power of the particle diameter, so that the scattering is reduced and the transparency is improved as the particle diameter decreases. Further, when the particle diameter is 100 nm or less, the scattered light is preferably extremely small. From the viewpoint of avoiding light scattering, a smaller particle diameter is preferable. Moreover, if the particle diameter is 1 nm or more, industrial production and handling are easy.

In addition, from the viewpoint of improving the conductivity of the conductive particles, the shape of the conductive particles used in the present invention is preferably a needle shape or a plate shape. This is because the reason why the conductivity of the conductor is lowered is the contact resistance value between the particles, so that the number of contact points between the particles is reduced if the shape of the conductive particles is a needle-like or plate-like particle dispersion. This is because it becomes easier to obtain a conductor having higher conductivity.
Therefore, when the conductive particles used in the present invention include needle-like crystals or all are plate-like crystals, the thickness of the plate-like crystal particles is 1 nm or more and 100 μm or less, and a diagonal line on the plate-like surface. The maximum value of the length is 5 nm or more and 500 μm or less, and the ratio between the maximum value of the diagonal line on the plate-like surface and the thickness of the plate-like crystal is 5 or more.

  The dust resistance value of the conductive particles used in the present invention obtained as described above measured under a pressure of 9.8 MPa was 1.0 Ω · cm or less. If the said dust resistance value is 1.0 ohm * cm or less, since an effective conductor film is obtained and an application range is expanded, it is preferable.

The tungsten oxide particles constituting the conductive particles of the present embodiment are represented by the general formula W _y O _Z (W is tungsten, O is oxygen, 2.45 ≦ z / y ≦ 2.999). It is preferable to include a Magneli phase having a composition ratio. This is because the “magnet phase” is chemically stable and preferable as a conductive material.

Here, the conductive mechanism of the transparent conductive film according to the present invention will be briefly described with reference to the drawings. Here, FIGS. 1A to 1D are schematic views showing the crystal structures of tungsten oxide and composite tungsten oxide, and FIG. 1A shows the crystal structure of W ₁₈ O ₄₉ ((010) projection), (B) is the crystal structure of cubic tungsten bronze ((010) projection), (C) is the crystal structure of tetragonal tungsten bronze ((001) projection), and (D) is the crystal structure of hexagonal tungsten bronze. ((001) projection).
Regarding the structure of tungsten trioxide, an octahedral structure formed of WO ₆ can be considered as one unit. In this octahedral structure, W atoms are located, oxygen is located at each vertex of the octahedral structure, and all the octahedral structures share each vertex with the adjacent octahedral structure. At this time, no conduction electrons exist in this structure. On the other hand, the magnetic phase represented by a composition ratio such as WO _2.9 has a structure in which the octahedral structure of WO ₆ is regularly shared by ridge sharing and vertex sharing. In addition, W ₁₈ O ₄₉ (WO _2.72 ) having a structure as shown in FIG. 1A is composed of a decagonal structure with WO ₁₀ as one unit and an octahedral structure of WO ₆ in which a ridge is shared. A shared regular structure. In the tungsten oxide having such a structure, it is considered that electrons emitted from oxygen contribute as conduction electrons and develop conductivity.
Even if the above structure of tungsten trioxide is uniform, non-uniform, or amorphous, conduction electrons are generated, and conductive characteristics can be obtained.

Further, the composite tungsten oxide represented by M _x W _y O _z preferably includes an amorphous structure or a cubic, tetragonal, or hexagonal tungsten bronze structure.

  In this composite tungsten oxide, as shown in FIGS. 1 (B) to (D), the M element is located in a void formed by sharing the apex of the octahedral structure. It is considered that conduction electrons are generated by the addition of these M elements. The structure of the composite tungsten oxide is typically cubic, tetragonal, or hexagonal, and examples of each structure are shown in FIGS. 1B, 1C, and 1D. These composite tungsten oxides have an upper limit of the amount of additive element derived from the structure, and the maximum amount of additive M element added to 1 mol of W is 1 mol in the case of cubic crystal and in the case of tetragonal crystal. About 0.5 mol (although it varies depending on the additive element, it is about 0.5 mol that is easy to produce industrially), and in the case of hexagonal crystal, it is 0.33 mol. However, it is difficult to simply define these structures, and the range of the maximum addition amount of the additive element M is an example showing a particularly preferable range, and the present invention is not limited to this. is not. In addition, a variety of structures can be adopted by combining materials in the crystal structure, and the above-described structure is also a representative example and is not limited thereto.

  In the composite tungsten oxide, the optical characteristics change depending on the structure. In particular, in the near-infrared light absorption region derived from conduction electrons, hexagonal crystals tend to be the longest wavelength side, and there is little absorption in the visible light region. Next is a tetragonal crystal, and cubic crystals tend to absorb light from conduction electrons on the shorter wavelength side, and also increase the absorption in the visible light region. Therefore, a composite tungsten oxide having a hexagonal crystal structure is preferable for the transparent conductive film that transmits more visible light for the reasons described above.

In general, it is known that a hexagonal crystal is formed when an element M having a large ionic radius is added to a composite tungsten oxide. Specifically, Cs, K, Rb, Tl, Ba, In, Li, When each element of Ca, Sr, Fe, and Sn is added, it is preferable because a hexagonal crystal is easily formed. However, other than these elements, the additive element M only needs to be present in the hexagonal voids as shown in FIG. 1D, which are formed by WO ₆ units, and are not limited to the above elements. Further, the composite tungsten oxide having a hexagonal crystal structure may have a uniform crystal structure or an irregular structure.
Here, for the tungsten trioxide (WO ₃ ), the above-described control of the amount of oxygen and the addition of the M element that generates conduction electrons may be used in combination. Moreover, when using the said transparent conductive film as a near-infrared shielding film, what is necessary is just to select the material which suited the objective timely, for example, M element.

When the conductive particles of the composite tungsten oxide having a hexagonal crystal structure form a uniform crystal structure, the additive element M is preferably added in an amount of 0.1 to 0.4, more preferably 0.33. . This is because a value theoretically calculated from the crystal structure is 0.33, and preferable conductive characteristics can be obtained with the addition amount before and after this value.
Cubic crystals and tetragonal crystals are known as the conductive particles of composite tungsten oxide (so-called tungsten bronze) (FIGS. 1B and 1C). These particles also have a wider transmission region in the visible light region than the tungsten oxide to which the additive element M is not added, and are useful for the purpose of transmitting the visible light region more. For example, when Na or the like is added, a cubic crystal structure is formed, and when Ba or K is added, a tetragonal crystal structure is easily obtained.

The shape of the conductive particles of this embodiment is one or more of granular, needle-like, or plate-like. The tungsten oxide particles and the composite tungsten oxide particles constituting the conductive particles are easily generated in a needle shape (for example, a W ₁₈ O ₄₉ (WO _2.72 ) needle crystal according to Example 1 described later). (See FIGS. 4A and 4B showing SEM observation images.) When the dispersion is used, it is easier to obtain better conductive characteristics. The hexagonal tungsten bronze can be formed into a plate shape (for example, an SEM observation image of a plate crystal of hexagonal tungsten bronze Cs _0.35 WO _{3 according} to Example 4 described later). 6 (A) and 6 (B) shown in FIG. 6), it is effective to obtain good conductivity when a conductor is used.

  Furthermore, since the conductive particles according to the present invention do not use high-cost raw materials such as In and noble metals as compared with the case where ITO particles or noble metal particles are used, the visible light transmissive particle-dispersed conductor described below is inexpensive. Obtainable.

2. Method for Producing Conductive Particles Conductive particles comprising a tungsten oxide represented by the above general formula WyOz (W is tungsten, O is oxygen, 2.2 ≦ z / y ≦ 2.999), and / or Or M _x W _y O _z (where M element is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, One or more elements selected from V, Mo, Ta, Re, Be, Hf, Os, Bi, I, W is tungsten, O is oxygen, 0.001 ≦ x / y ≦ 1.1, 2 .2 ≦ z / y ≦ 3.0). Sex particles, tungsten compound as a raw material of the conductive particles (hereinafter, referred to as the tungsten compound starting raw material) was obtained by heat treatment in an inert gas and / or reducing gas atmosphere. Thereby, the said electroconductive particle can be obtained cheaply by a simple method.

  The tungsten compound starting material for the conductive particles is tungsten trioxide, tungsten dioxide, hydrated tungsten oxide, tungsten hexachloride, ammonium tungstate, tungstic acid, or tungsten hexachloride as an alcohol. Tungsten oxide hydrate obtained by dissolving in water and drying, or tungsten oxide water obtained by dissolving and adding tungsten hexachloride dissolved in alcohol and then precipitating it It is preferable that it is at least one selected from a hydrate, a tungsten compound obtained by drying an ammonium tungstate aqueous solution, or metallic tungsten.

  When manufacturing conductive particles of tungsten oxide, it is more preferable to use tungsten trioxide, tungsten oxide hydrate powder, tungstic acid, or an aqueous solution of ammonium tungstate from the viewpoint of easy manufacturing process. . When producing conductive particles of composite tungsten oxide, if the tungsten compound starting material is a solution, each element can be easily mixed uniformly. From the standpoint of an aqueous solution of ammonium tungstate, a tungsten hexachloride solution, or a liquid. It is preferable to use tungstic acid or the like.

  Using these tungsten compound starting materials, heat treatment is performed at 100 ° C. to 850 ° C. in a reducing gas atmosphere, and then heat treatment is performed at a temperature of 550 ° C. to 1200 ° C. in an inert gas atmosphere as necessary. Thus, tungsten oxide particles and composite tungsten oxide particles having the above-described particle diameter (particle diameter of 1 nm to 10,000 μm) can be obtained.

The heat treatment conditions for producing the tungsten oxide particles are as follows.
As heat treatment conditions in a reducing atmosphere, first, it is preferable to heat-treat the tungsten compound starting material in a reducing gas atmosphere at 100 ° C. or higher and 850 ° C. or lower. If it is 100 degreeC or more, a reductive reaction will fully advance and it is preferable. Moreover, if it is 850 degrees C or less, reduction | restoration does not advance too much and it is preferable. The reducing gas is not particularly limited, but H ₂ is preferable. In the case H ₂ is used as the reducing gas, H ₂ of the composition of the reducing atmosphere is preferably in 0.1% or more by volume, more preferably 2% or more is good by volume. If H ₂ is 0.1% or more by volume, the reduction can proceed efficiently.

Next, if necessary, the particles obtained here are further heat-treated at a temperature of 550 ° C. or higher and 1200 ° C. or lower in an inert gas atmosphere in order to improve crystallinity or remove the adsorbed reducing gas. Is good. The heat treatment conditions in the inert gas atmosphere are preferably 550 ° C. or higher. The tungsten compound starting material heat-treated at 550 ° C. or higher shows sufficient conductivity. Also, it is better to use an inert gas, such as Ar, N ₂ is as the inert gas.
Through the above treatment, a tungsten oxide that is expressed by the general formula W _y O _z and _satisfies 2.45 ≦ z / y ≦ 2.999 and includes a magnetic phase can be obtained.

The heat treatment conditions for producing composite tungsten oxide particles are as follows.
The above tungsten compound starting material and M element (where M element is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni) , Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb , V, Mo, Ta, Re, Be, Hf, Os, Bi, I) or a powder mixed with a simple substance or a compound containing the compound, or the above tungsten compound starting material A powder obtained by mixing a solution or dispersion and a solution or dispersion of a compound containing the above M element and then drying is produced. At this time, the mixing ratio of the tungsten compound starting material and the M element is such that when the composite tungsten oxide is expressed as M _x W _y O _z , the composition ratio of the M element and tungsten in the composite tungsten oxide is 0. A predetermined value satisfying .001 ≦ x / y ≦ 1.

  Here, in order to produce a tungsten compound starting material in which each component is uniformly mixed at the molecular level, it is preferable to mix the materials in a solution, and the tungsten compound starting material containing M element is a solvent such as water or an organic solvent. It is preferable that it can be dissolved in. Examples thereof include tungstate, chloride, nitrate, sulfate, oxalate, oxide, carbonate, hydroxide, etc. containing M element, but are not limited to these and are in the form of a solution. If there is, it is preferable. From an industrial point of view, since the process of evaporating the solvent from the solution state is complicated, it is possible to mix and react with the solid. At this time, since it is industrially not preferable that toxic gas is generated from the raw material compound, the raw material used is preferably a tungstic acid and M element carbonate or hydroxide.

The heat treatment conditions are the same as the heat treatment conditions for producing the tungsten oxide particles described above. The following heat treatment conditions can be proposed for producing a composite tungsten oxide with good crystallinity. However, the heat treatment conditions differ depending on the starting material and the type of the target compound, and thus are not limited to the following methods.
When producing a composite tungsten oxide with good crystallinity, higher heat treatment conditions are preferred, and the reduction temperature is preferably 600 ° C. to 850 ° C., although it varies depending on the starting material and the H ₂ temperature during reduction. Furthermore, the heat treatment temperature in the subsequent inert atmosphere is preferably 700 ° C to 1200 ° C.

3. Visible Light Transmission Type Particle-Dispersed Conductor The conductive particles of the present embodiment can obtain visible light transparency by controlling the composition, particle size, and shape of the conductive particles as described above. As a result, a visible light transmitting particle-dispersed conductor can be formed at a lower cost than when ITO particles or noble metal particles are used.
As a method for applying the conductive particles, there is a method in which the conductive particles are dispersed in an appropriate medium by a dispersion method as described below to form a conductor on a desired substrate. This method can be applied to low heat-resistant base materials such as resin materials by dispersing conductive particles fired at high temperature in the base material or binding them to the base material surface with a binder. Therefore, it does not require a large-scale apparatus such as a vacuum film forming method when forming the conductor, and is inexpensive.

  The visible light transmissive particle-dispersed conductor of the present embodiment can be formed in a film shape, and can be formed by binding conductive particles fired at a high temperature in advance to the substrate surface with a binder. The binder is not particularly limited, but is preferably a transparent resin or a transparent dielectric.

(A) Method of Dispersing Conductive Particles in Medium and Forming on Substrate Surface For example, conductive particles according to this embodiment are dispersed in an appropriate solvent, and a medium resin is added thereto as necessary. If the resin is then cured by a predetermined method by coating the surface of the substrate and evaporating the solvent, a visible light transmissive particle-dispersed conductor film in which the conductive particles are dispersed in the medium can be formed. The coating method is not particularly limited as long as the resin containing conductive particles can be uniformly coated on the surface of the substrate, and examples thereof include a bar coating method, a gravure coating method, a spray coating method, and a dip coating method.

  For example, a UV curable resin, a thermosetting resin, an electron beam curable resin, a room temperature curable resin, a thermoplastic resin, or the like can be selected as the medium. Specifically, polyethylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, polystyrene resin, polypropylene resin, ethylene vinyl acetate copolymer, polyester resin, polyethylene terephthalate resin, fluorine resin, polycarbonate resin, acrylic resin And polyvinyl butyral resin. In addition, a binder using a metal alkoxide can be used as the medium. Representative examples of the metal alkoxide include alkoxides such as Si, Ti, Al, and Zr. Binders using these metal alkoxides can form oxide films by heating after hydrolysis.

  In addition, the conductive particles according to the present embodiment are dispersed in an appropriate solvent, coated on the surface of the base material, and the solvent is evaporated, so that the conductive particles are dispersed on the surface of the base material. A body membrane can be formed. However, since the strength of the conductive film alone is weak, it is preferable to apply a solution containing a resin or the like on the conductive film to evaporate the solvent and form a protective film. The coating method is not particularly limited as long as the resin containing conductive particles can be uniformly coated on the surface of the substrate, and examples thereof include a bar coating method, a gravure coating method, a spray coating method, and a dip coating method.

  The method for dispersing the conductive particles is not particularly limited, and for example, ultrasonic irradiation, bead mill, sand mill or the like can be used. Moreover, in order to obtain a uniform dispersion, various additives may be added or the pH may be adjusted.

  The base material may be a film shape or a board shape as desired, and the shape is not limited. As the transparent substrate, PET, acrylic, urethane, polycarbonate, polyethylene, ethylene vinyl acetate copolymer, vinyl chloride, fluorine resin, and the like can be used for various purposes. Moreover, glass other than resin can be used.

(B) Method of Dispersing as Particles in Base Material As another method for applying the conductive particles according to the present embodiment, the conductive particles may be dispersed in the base material. In order to disperse the conductive particles in the base material, the conductive particles may be permeated from the surface of the base material, and the conductive particles are melted at a temperature higher than the melting temperature of the base material. Then, it may be mixed with a resin. The resin containing the conductive particles thus obtained can be formed into a film shape or a board shape by a predetermined method and applied as a conductive material.

  For example, as a method of dispersing conductive particles in PET resin, first, a dispersion of PET resin and conductive particles is mixed, the dispersion solvent is evaporated, and then heated to about 300 ° C. which is the melting temperature of PET resin, By melting, mixing, and cooling the PET resin, it is possible to produce a PET resin in which conductive particles are dispersed.

4). Shape of Particles The conductive particles of tungsten oxide and the conductive particles of composite tungsten oxide can form needle-like crystals as shown in FIG. 4 by an appropriate heat treatment. Compared with fine granular particles, acicular crystals have the effect of improving the conductivity of the visible light transmissive particle-dispersed conductor film. The reason for this is that the visible light transmission type particle-dispersed conductor film is deteriorated in the resistance value of the film as compared with the bulk due to the contact resistance value between the particles. This is because each one becomes a conductive path, so that the contact resistance value is small compared to the connection of fine granular particles, and electrons are efficiently transported, so that the conductivity is improved.

  The conductive particles of hexagonal tungsten bronze, which are conductive particles of composite tungsten oxide, can form a plate-like crystal shown in FIG. In particular, when the additive element M is added in an amount greater than 0.33, a plate-like crystal is easily formed. Since the obtained plate-like crystal can reduce the contact resistance value per unit area as compared with fine particles when dispersed, it is easy to improve conductivity.

  However, since the acicular crystals 5 and the plate crystals have a certain size, they are likely to scatter light and may reduce transparency. In order to improve the transparency, it is necessary to pulverize the acicular crystals and plate crystals into a fine shape, and it is preferable to change the particle shape according to the purpose. The pulverization method may be a normal pulverization method.

5. Optical Properties of Visible Light Transmitting Particle-Dispersed Conductor Optical properties of the visible light transmitting particle-dispersed conductor according to the present embodiment are measured using a spectrophotometer (U-4000 manufactured by Hitachi, Ltd.), and visible light transmittance is measured. (Based on JIS R3106) was calculated.

As an example of the measurement result of transmittance, FIG. 2 shows a transmission profile of a visible light transmissive particle-dispersed conductor formed from W ₁₈ O ₄₉ conductive particles. FIG. 2 is a graph in which the horizontal axis represents the wavelength of transmitted light and the vertical axis represents the light transmittance (%). As is apparent from FIG. 2, the visible light transmissive particle-dispersed conductor film formed from the W ₁₈ O ₄₉ conductive particles transmits visible light having a wavelength of 380 nm to 780 nm. It has been found (for example, the transmittance of visible light having a wavelength of 500 nm is 60%).

FIG. 3 shows a transmission profile of Cs _0.33 WO ₃ as an example of a transmission profile of a visible light transmissive particle-dispersed conductor formed from conductive particles of hexagonal composite tungsten oxide. FIG. 3 is a graph in which the wavelength of light transmitted on the horizontal axis is taken and the light transmittance (%) is taken on the vertical axis. As is apparent from FIG. 3, the visible light transmissive particle-dispersed conductive film having Cs _0.33 WO ₃ transmits visible light having a wavelength of 380 nm to 780 nm, and has a visible light region transmittance. Turned out to be excellent.

  Furthermore, the visible light transmission type particle-dispersed conductor does not require a large-scale film forming apparatus such as a vacuum film forming method such as a sputtering method, a vapor deposition method, an ion plating method, and a chemical vapor deposition method (CVD method). Since the visible light transmission type particle dispersed conductor can be formed by a coating method or the like, it is inexpensive and industrially useful.

The present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.
In this example, the optical characteristics of the visible light transmissive particle-dispersed conductor were measured using a spectrophotometer (U-4000 manufactured by Hitachi, Ltd.), and the visible light transmittance (based on JIS R3106) was calculated. . The haze value was measured using a measuring device HR-200 manufactured by Murakami Color Research Laboratory based on JIS K 7105. Furthermore, the average dispersed particle size was measured with a measuring device (ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)) using a dynamic light scattering method, and the average value of three measurements was taken as the average dispersed particle size. In addition, the evaluation of the conductive property was performed by measuring the surface resistance value of the produced film. The surface resistance value of this film was measured using Hiresta IP MCP-HT260 manufactured by Mitsubishi Yuka.
Furthermore, the measurement of dust resistance is performed by the van der Pauw method (4th edition, Experimental Chemistry Lecture 9 Electricity / Magnetic June 5, 1991, Editor: The Chemical Society of Japan, Publisher: Maruzen Co., Ltd.) See). The sample is a pressed pellet pressed into a disk shape of 10 mmφ, and four terminal electrodes are installed at 90 ° intervals on the disk surface, and a current is passed between two adjacent terminals while applying a pressure of 9.8 MPa. Then, the voltage between the remaining two terminals is measured and the resistance value is calculated.

Example 1
Tungsten hexachloride was dissolved in ethanol and dried at 130 ° C. to prepare a tungsten oxide hydrate. This was heated in a reducing atmosphere (argon / hydrogen = 95/5 volume ratio) at 550 ° C. for 1 hour, once returned to room temperature, and then heated in an argon atmosphere at 800 ° C. for 1 hour to obtain the target tungsten oxide powder. Produced.
As a result of identification of the crystal phase by X-ray diffraction, the obtained powder was a so-called magnetic phase of W ₁₈ O ₄₉ (WO _2.72 ). The result of observing the shape of this powder by SEM is shown in FIGS. Here, (A) is a 10,000 times SEM image of W ₁₈ O ₄₉ , and (B) is a 3000 times SEM image.
Then, needle-like crystals were observed as shown in FIGS. 4 (A) and 4 (B). Moreover, the dust resistance value which measured this powder under the pressure of 9.8 MPa was 0.085 ohm * cm, and favorable electroconductivity was confirmed.

This WO _2.72 conductive particle powder was mixed with 20 parts by weight, 79 parts by weight of toluene, and 1 part by weight of a dispersant, and dispersed by irradiating with ultrasonic waves in order to disperse while maintaining the shape of needle crystals. Treatment was performed to prepare a dispersion. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a visible light transmissive particle-dispersed conductor film (hereinafter simply referred to as a conductor film).

The optical properties of this conductor film were measured and found to be as follows. It was found that the visible light transmittance was 63% and the light in the visible light region was sufficiently transmitted. Further, the haze value was 3.5%, the transparency was high, the transmitted color tone was a beautiful blue color, and the surface resistance value was 7.6 × 10 ⁸ Ω / □.

(Example 2)
The aqueous ammonium metatungstate solution was dried at 130 ° C. to obtain a powdered tungsten oxide compound. This was heated at 550 ° C. for 1 hour in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). And after returning to room temperature once, the tungsten oxide powder was produced by heating in 800 degreeC argon atmosphere for 1 hour. As a result of identification of the crystal phase by X-ray diffraction, a crystal phase of W ₁₈ O ₄₉ (WO _2.72 ) was observed. Thus, even when the metatungstic acid aqueous solution was used as the tungsten compound starting material, conductive particles equivalent to those in Example 1 could be produced. The powder resistance value obtained by measuring the powder of the conductive particles under a pressure of 9.8 MPa was 0.089 Ω · cm, and good conductivity was confirmed.

(Example 3)
Carbonic acid Cs and tungstic acid were mixed in a mortar so that the molar ratio of Cs / W was 0.33. This was heated at 600 ° C. for 2 hours in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating 1 hour at 800 ° C. in an argon atmosphere was returned to room temperature _to prepare a powder of conductive particles _{Cs 0.33} WO _3. This Cs _0.33 WO ₃ was hexagonal tungsten bronze as a result of identification of the crystal phase by X-ray diffraction. The result of having observed the shape of the obtained electroconductive particle powder by SEM is shown in FIG. Here, FIG. 5 is a 10,000 times SEM image of Cs _0.33 WO ₃ .
Then, as shown in FIG. 5, hexagonal column crystals were observed. The dust resistance value of this conductive particle powder measured under a pressure of 9.8 MPa was 0.013 Ω · cm, and good conductivity was confirmed.

20 parts by weight of the conductive particle powder of Cs _0.33 WO ₃ , 79 parts by weight of toluene and 1 part by weight of a dispersant were mixed, and dispersion treatment was performed using a medium stirring mill to obtain a dispersion liquid having an average dispersed particle of 100 nm. Was made. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductor film.

The optical properties of this conductor film were measured and found to be as follows. It was found that the visible light transmittance was 77% and the light in the visible light region was sufficiently transmitted. Further, the haze value was 0.2%, and the transparency was high and the internal situation could be clearly confirmed from the outside. The transmitted color tone was beautiful blue, and the surface resistance value was 2.8 × 10 ⁹ Ω / □.

Example 4
Carbonic acid Cs and tungstic acid were mixed in a mortar so that the Cs / W ratio was 0.35. This was heated at 600 ° C. for 2 hours in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating 1 hour at 800 ° C. in an argon atmosphere was returned to room temperature _to prepare a powder of conductive particles _{Cs 0.35} WO _3. As for this Cs _0.35 WO ₃ , as a result of identification of the crystal phase by X-ray diffraction, a hexagonal crystal phase was observed. The result of SEM observation of the obtained powder is shown in FIGS. Here, (A) is a SEM image of Cs _0.35 WO ₃ 5,000 times, and (B) is a SEM image of 10,000 times.
Then, plate-like crystals were observed as shown in FIG. Thus, it was found that a plate-like crystal was formed by increasing the amount of Cs added from 0.33. The powder resistance value of this powder measured under a pressure of 9.8 MPa was 0.0096 Ω · cm, and good conductivity was confirmed.

(Example 5)
Carbonic acid Cs and tungstic acid were mixed in a mortar so that the Cs / W ratio was 0.33. This was heated in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio) at 600 ° C. for 2 hours to produce a conductive particle powder of Cs _0.33 WO ₃ . As for this Cs _0.33 WO ₃ , as a result of identification of the crystal phase by X-ray diffraction, a hexagonal crystal phase was observed. In SEM observation of the obtained powder, fine crystals of hexagonal columns were observed. The powder resistance value of this powder measured under a pressure of 9.8 MPa was 0.013 Ω · cm, and good conductivity was confirmed.

20 parts by weight of the conductive particle powder of Cs _0.33 WO ₃ , 79 parts by weight of toluene and 1 part by weight of a dispersing agent are mixed, and dispersion treatment is performed using a medium stirring mill to obtain a dispersion liquid having average dispersed particles of 120 nm. Was made. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductor film.

The optical properties of this conductor film were measured and found to be as follows. The visible light transmittance was 63%, and it was found that the light in the visible light region was sufficiently transmitted. Further, the haze value was 0.8%, and the transparency was high and the internal situation could be clearly confirmed from the outside. . The transmitted color tone was a beautiful blue color, and the surface resistance value was 3.6 × 10 ⁸ Ω / □.

(Example 6)
Carbonic acid Rb and tungstic acid were mixed in a mortar so that the ratio of Rb / W was 0.33. This was heated at 600 ° C. for 2 hours in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating 1 hour at 800 ° C. in an argon atmosphere was returned to room temperature _to prepare a powder of conductive particles _{Rb 0.33} WO _3. As for this Rb _0.33 WO ₃ , as a result of identification of the crystal phase by X-ray diffraction, a hexagonal crystal phase was observed. In SEM observation of the obtained conductive particle powder, hexagonal columnar fine crystals were observed. The dust resistance value obtained by measuring the powder of the conductive particles under a pressure of 9.8 MPa was 0.0086 Ω · cm, and good conductivity was confirmed.

20 parts by weight of the conductive particle powder of Rb _0.33 WO ₃ , 79 parts by weight of toluene and 1 part by weight of a dispersing agent are mixed, and dispersion treatment is performed using a medium stirring mill to obtain a dispersion liquid having an average dispersed particle of 80 nm. Was made. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductor film.

The optical properties of this conductor film were measured and found to be as follows. It was found that the visible light transmittance was 76% and the light in the visible light region was sufficiently transmitted. Further, the haze value was 0.2%, and the transparency was high and the internal situation could be clearly confirmed from the outside. The transmitted color tone was beautiful blue, and the surface resistance value was 4.2 × 10 ⁸ Ω / □.

(Example 7)
Carbonic acid Rb and tungstic acid were mixed in a mortar so that the ratio of Rb / W was 0.33. This was heated at 600 ° C. for 2 hours in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating for 100 hours at 800 ° C. in an argon atmosphere was returned to room temperature _to prepare a powder of _{Rb 0.33} WO _3. As for this Rb _0.33 WO ₃ , as a result of identification of the crystal phase by X-ray diffraction, a hexagonal crystal phase was observed. The result of SEM observation of the obtained powder is shown in FIGS. Here, (A) is a 200 times SEM image of Rb _0.33 WO ₃ , and (B) is a 1000 times SEM image.
Then, as shown in FIGS. 7A and 7B, hexagonal columnar fibrous crystals were observed.
The powder resistance value of this powder was measured and found to be 0.0046 Ω · cm. Good conductivity was confirmed.

20 parts by weight of this Rb _0.33 WO ₃ powder, 79 parts by weight of toluene, and 1 part by weight of a dispersant were mixed and subjected to dispersion treatment by ultrasonic irradiation to prepare a dispersion of fibrous particles. 10 parts by weight of this liquid and 0.1 part by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied and formed on a glass using a bar coater. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductive film.
When the optical properties of this conductive film were measured, it was found that the visible light transmittance was 56% and that the light in the visible light region was sufficiently transmitted. Further, the haze was 8.2%, and the transparency was high and the internal The situation was clearly confirmed from the outside. The transmission color tone was beautiful blue. The surface resistance value was 3.1 × 10 ⁶ Ω / □.

(Example 8)
Carbonic acid K and tungstic acid were mixed in a mortar so that the K / W ratio was 0.33. This was heated at 600 ° C. for 2 hours in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating 1 hour at 800 ° C. in an argon atmosphere was returned to room temperature to prepare a powder of conductive particles K _0.33 WO _3. As for this K _0.33 WO ₃ , as a result of identification of the crystal phase by X-ray diffraction, a hexagonal crystal phase was observed. In SEM observation of the obtained conductive particle powder, hexagonal columnar fine crystals were observed. Moreover, the dust resistance value which measured the powder of this electroconductive particle under the pressure of 9.8 MPa was 0.049 ohm * cm, and favorable electroconductivity was confirmed.

20 parts by weight of the conductive particle powder of K _0.33 WO ₃ , 79 parts by weight of toluene, and 1 part by weight of a dispersant are mixed and dispersed using a medium stirring mill to obtain a dispersion liquid having an average dispersed particle of 80 nm. Was made. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductor film.

The optical properties of this conductor film were measured and found to be as follows. It was found that the visible light transmittance was 62% and the light in the visible light region was sufficiently transmitted. Furthermore, the haze value was 0.9%, and the transparency was high and the internal situation could be clearly confirmed from the outside. The transmitted color tone was beautiful blue, and the surface resistance value was 7.3 × 10 ⁹ Ω / □.

Example 9
Carbonic acid Ba and tungstic acid were mixed in a mortar so that the Ba / W ratio was 0.33. This was heated at 550 ° C. for 2 hours in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating 1 hour at 700 ° C. in an argon atmosphere was returned to room temperature _to prepare a powder of conductive particles _{Ba 0.33} WO _3. As for Ba _0.33 WO ₃ , a hexagonal crystal phase was observed as a result of identification of the crystal phase by X-ray diffraction. In SEM observation of the obtained conductive particle powder, hexagonal columnar fine crystals were observed. The powder resistance value obtained by measuring the powder of the conductive particles under a pressure of 9.8 MPa was 0.068 Ω · cm, and good conductivity was confirmed.

20 parts by weight of the conductive particle powder of Ba _0.33 WO ₃ , 79 parts by weight of toluene, and 1 part by weight of a dispersant are mixed and subjected to a dispersion treatment using a medium stirring mill to obtain a dispersion having an average dispersed particle of 95 nm. Was made. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductor film.

The optical properties of this conductor film were measured and found to be as follows. It was found that the visible light transmittance was 55% and the light in the visible light region was sufficiently transmitted. Furthermore, the haze value was 1.3%, and the transparency was high and the internal situation could be clearly confirmed from the outside. The transmitted color tone was a beautiful blue color, and the surface resistance value was 3.6 × 10 ¹⁰ Ω / □.

(Example 10)
Tl chloride was dissolved in an aqueous ammonium metatungstate solution. At this time, the mixture was mixed so that the ratio of Tl / W was 0.33. This was heated at 600 ° C. for 2 hours in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating 1 hour at 800 ° C. in an argon atmosphere was returned to room temperature _to prepare a powder of conductive particles _{Tl 0.33} WO _3. As for this Tl _0.33 WO ₃ , as a result of identification of the crystal phase by X-ray diffraction, a hexagonal crystal phase was observed. In SEM observation of the obtained conductive particle powder, hexagonal columnar fine crystals were observed. The powder resistance value obtained by measuring the powder of the conductive particles under a pressure of 9.8 MPa was 0.096 Ω · cm, and good conductivity was confirmed.

20 parts by weight of this Tl _0.33 WO ₃ conductive particle powder, 79 parts by weight of toluene and 1 part by weight of a dispersant were mixed, and dispersion treatment was carried out using a medium stirring mill to obtain a dispersion liquid having an average dispersed particle of 85 nm. Was made. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductor film.

The optical properties of this conductor film were measured and found to be as follows. It was found that the visible light transmittance was 72% and the light in the visible light region was sufficiently transmitted. Further, the haze value was 1.1%, and the transparency was high and the internal situation could be clearly confirmed from the outside. The transmitted color tone was beautiful blue, and the surface resistance value was 6.2 × 10 ¹¹ Ω / □.

(Example 11)
In chloride was dissolved in an aqueous solution of ammonium metatungstate. At this time, the mixture was mixed so that the In / W ratio was 0.33. This was heated at 500 ° C. for 1 hour in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating 1 hour at 700 ° C. in an argon atmosphere was returned to room temperature _to prepare a powder of conductive particles _{In 0.33} WO _3. As a result of identification of the crystal phase by X-ray diffraction, a hexagonal crystal phase was observed in this In _0.33 WO ₃ . In SEM observation of the obtained conductive particle powder, hexagonal columnar fine crystals were observed. The powder resistance value obtained by measuring the powder of the conductive particles under a pressure of 9.8 MPa was 0.032 Ω · cm, and good conductivity was confirmed.

20 parts by weight of this In _0.33 WO ₃ conductive particle powder, 79 parts by weight of toluene, and 1 part by weight of a dispersant were mixed, and dispersion treatment was performed using a medium stirring mill to obtain a dispersion liquid having average dispersed particles of 110 nm. Was made. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductor film.

The optical properties of this conductor film were measured and found to be as follows. It was found that the visible light transmittance was 75% and the light in the visible light region was sufficiently transmitted. Furthermore, the haze value was 1.3%, and the transparency was high and the internal situation could be clearly confirmed from the outside. The transmitted color tone was beautiful blue, and the surface resistance value was 3.5 × 10 ⁹ Ω / □.

(Example 12)
Carbonic acid K and tungstic acid were mixed in a mortar so that the K / W ratio was 0.55. This was heated at 600 ° C. for 2 hours in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating 1 hour at 800 ° C. in an argon atmosphere was returned to room temperature to prepare a powder of conductive particles K _0.55 WO _3. As for this K _0.55 WO ₃ , as a result of identification of the crystal phase by X-ray diffraction, a tetragonal crystal phase was observed. In SEM observation of the obtained conductive particle powder, rectangular parallelepiped fine crystals were observed. The powder resistance value obtained by measuring the powder of the conductive particles under a pressure of 9.8 MPa was 0.12 Ω · cm, and good conductivity was confirmed.

20 parts by weight of the conductive particle powder of K _0.55 WO ₃ , 79 parts by weight of toluene, and 1 part by weight of a dispersant are mixed and dispersed using a medium stirring mill to obtain a dispersion liquid having an average dispersed particle of 95 nm. Was made. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductor film.

The optical properties of this conductor film were measured and found to be as follows. It was found that the visible light transmittance was 62% and the light in the visible light region was sufficiently transmitted. Furthermore, the haze value was 1.2%, and the transparency was high and the internal situation could be clearly confirmed from the outside. The transmitted color tone was beautiful blue, and the surface resistance value was 5.7 × 10 ¹¹ Ω / □.

(Example 13)
Na carbonate and tungstic acid were mixed in a mortar so that the ratio of Na / W was 0.50. This was heated at 600 ° C. for 2 hours in a reducing atmosphere (argon / hydrogen = 97/3 volume ratio). Then, once by heating 1 hour at 800 ° C. in an argon atmosphere was returned to room temperature _to prepare a powder of conductive particles _{Na 0.50} WO _3. As for this Na _0.50 WO ₃ , a tetragonal crystal phase was observed as a result of identification of the crystal phase by X-ray diffraction. The dust resistance value obtained by measuring the powder of the conductive particles under a pressure of 9.8 MPa was 0.18 Ω · cm, and good conductivity was confirmed.

The conductive particles of Na _0.50 WO ₃ were mixed with 20 parts by weight of powder, 79 parts by weight of toluene and 1 part by weight of a dispersant, and subjected to dispersion treatment using a medium stirring mill. Was made. 10 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a conductor film.

The optical properties of this conductor film were measured and found to be as follows. It was found that the visible light transmittance was 52% and the light in the visible light region was sufficiently transmitted. Furthermore, the haze value was 0.6%, and the transparency was high and the internal situation could be clearly confirmed from the outside. The transmitted color tone was beautiful blue, and the surface resistance value was 4.8 × 10 ¹¹ Ω / □.

(Comparative Example 1)
20 parts by weight of commercially available tungsten trioxide powder, 79.5 parts by weight of toluene, and 1.0 part by weight of a dispersant were mixed and subjected to dispersion treatment using a medium stirring mill to prepare a dispersion liquid having an average dispersed particle of 80 nm. . 20 parts by weight of this dispersion and 0.1 parts by weight of an ultraviolet curable resin for hard coat (solid content: 100%) were mixed. This solution was applied on a glass using a bar coater to form a film. This film was dried at 60 ° C. for 30 seconds to evaporate the solvent, and then cured with a high-pressure mercury lamp to obtain a thin film.

When the optical characteristics of this thin film were measured, the visible light transmittance was 89%, and most of the light in the visible light region was transmitted, but the surface resistance value was not measurable, and application as a conductor film was difficult. It was.
As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this.
Table 1 shows a list of measurement results of Examples 1 to 13 and Comparative Example 1.

It is a schematic diagram showing a crystal structure of tungsten _oxide, a crystalline structure of _W 18 _{O 49} ((010) projection). It is the schematic which shows the crystal structure of tungsten oxide, and is a crystal structure ((010) projection) of cubic tungsten bronze. It is the schematic which shows the crystal structure of a tungsten oxide, and is a crystal structure ((001) projection) of a tetragonal tungsten bronze. It is the schematic which shows the crystal structure of a tungsten oxide, and is the crystal structure ((001) projection) of a hexagonal tungsten bronze. W ₁₈ is a graph showing transmission Ploy file of visible light is formed from conductive particles O ₄₉ transmissive particles dispersed conductors. It is a graph showing the transmission profile of the formed conductive particles of the hexagonal composite tungsten oxide Cs _0.33 WO ₃ visible light transmissive particles dispersed conductors. 2 is an enlarged view showing an SEM observation image of a needle-like crystal of a magnetic phase W ₁₈ O ₄₉ (WO _2.72 ) which is a conductive particle obtained in Example 1. FIG. FIG. 5 is an overall view of FIG. 4 is an SEM observation image of hexagonal tungsten bronze Cs _0.33 WO ₃ hexagonal columnar crystals that are conductive particles obtained in Example 3. 6 is an enlarged view showing an SEM observation image of a plate-like crystal of hexagonal tungsten bronze Cs _0.35 WO ₃ which is a conductive particle obtained in Example 4. FIG. 6 is an enlarged view showing an SEM observation image of a plate-like crystal of hexagonal tungsten bronze Cs _0.35 WO ₃ which is a conductive particle obtained in Example 4. FIG. 6 is an enlarged view showing an SEM observation image of a fibrous crystal of hexagonal tungsten bronze Rb _0.35 WO ₃ which is conductive particles obtained in Example 7. FIG. FIG. 8 is an overall view of FIG.

Claims (14)

The tungsten oxide magnetic phase represented by the general formula WyOz (W is tungsten, O is oxygen, z / y = 2.72 ), or / and the general formula MxWyOz (where the M element is Cs, Rb, One or more elements selected from K, Na, Ba, In, and Tl, W is tungsten, O is oxygen, 0.33 ≦ x / y ≦ 0.55, z / y = 3 ) A composite tungsten oxide having a hexagonal tungsten bronze structure, a particle diameter of 1 nm or more, visible light permeability, and the particles were measured under a pressure of 9.8 MPa. A visible light transmission type particle-dispersed conductor comprising a plurality of conductive particles having a dust resistance of 1.0 Ω · cm or less.   2. The visible light transmissive particle-dispersed conductor according to claim 1, wherein the shape of the conductive particles is at least one of a granular shape, a needle shape, and a plate shape.   The conductive particles include needle-like crystals or are all needle-like crystals, and the ratio of the major axis to the minor axis (major axis / minor axis) in the acicular crystal is 5 or more, and The visible light transmission type particle-dispersed conductor according to claim 1 or 2, wherein the length of the major axis is 5 nm or more and 10,000 µm or less.   The conductive particles include a plate-like crystal or are all plate-like crystals, the plate-like crystal has a thickness of 1 nm or more and 100 μm or less, and a pair of plate-like surfaces in the plate-like crystal. The maximum value of the angular length is 5 nm or more and 500 μm or less, and the ratio of the maximum value of the diagonal length and the thickness of the plate crystal (maximum value of the diagonal length / thickness) is 5 or more. The visible light transmissive particle-dispersed conductor according to claim 1 or 2.   The visible light transmissive particle-dispersed conductor according to claim 1, wherein the visible light transmissive particle-dispersed conductor is a film.   6. The visible light transmitting particle dispersed conductor according to claim 1, wherein the visible light transmitting particle dispersed conductor contains a binder.   The visible light transmissive particle-dispersed conductor according to claim 6, wherein the binder is a transparent resin or a transparent dielectric. The tungsten oxide magnetic phase represented by the general formula WyOz (W is tungsten, O is oxygen, z / y = 2.72 ), or / and the general formula MxWyOz (where the M element is Cs, Rb, One or more elements selected from K, Na, Ba, In, and Tl, W is tungsten, O is oxygen, 0.33 ≦ x / y ≦ 0.55, z / y = 3 ) A composite tungsten oxide having a hexagonal tungsten bronze structure, a particle diameter of 1 nm or more, visible light permeability, and the particles were measured under a pressure of 9.8 MPa. Conductive particles having a dust resistance value of 1.0 Ω · cm or less.   A visible light transmission type conductive article, wherein the visible light transmission type particle dispersed conductor according to claim 1 is formed on a substrate. The tungsten oxide magnetic phase represented by the general formula WyOz (W is tungsten, O is oxygen, z / y = 2.72 ), or / and the general formula MxWyOz (where the M element is Cs, Rb, One or more elements selected from K, Na, Ba, In, and Tl, W is tungsten, O is oxygen, 0.33 ≦ x / y ≦ 0.55, z / y = 3 ) A method for producing conductive particles comprising a composite tungsten oxide having a hexagonal tungsten bronze structure as a crystal structure,
A method for producing conductive particles, wherein the conductive particles are produced by heat-treating a tungsten compound as a raw material of the conductive particles in a reducing gas and / or inert gas atmosphere.   The method for producing conductive particles according to claim 10, wherein the heat treatment is performed by heat-treating a tungsten compound as a raw material of the conductive particles in a reducing gas atmosphere at 100 ° C or higher and 850 ° C or lower.   In the heat treatment, a tungsten compound as a raw material of the conductive particles is heat-treated at 100 ° C. or higher and 850 ° C. or lower in a reducing gas atmosphere, and then at a temperature of 550 ° C. or higher and 1200 ° C. or lower in an inert gas atmosphere. The method for producing conductive particles according to claim 10, wherein heat treatment is performed.   After the tungsten compound used as the raw material for the conductive particles dissolves tungsten trioxide, tungsten oxide, tungsten oxide hydrate, tungsten hexachloride, ammonium tungstate, tungstic acid and tungsten hexachloride in alcohol. Tungsten oxide hydrate obtained by drying, tungsten oxide hydrate obtained by dissolving tungsten hexachloride in alcohol and then adding water to form a precipitate and drying the precipitate The method for producing conductive particles according to claim 10 or 12, wherein the method is one or more selected from a tungsten compound obtained by drying an aqueous ammonium acid solution and metallic tungsten. A tungsten compound as a raw material for the conductive particles according to claim 13 and an M element (provided that the M element is one or more elements selected from Cs, Rb, K, Na, Ba, In, and Tl). Or a powder obtained by mixing a solution or dispersion of the tungsten compound with a solution or dispersion of the compound containing the M element and drying the mixture. 14. The method for producing conductive particles according to claim 10, wherein at least one selected from the above is used as a tungsten compound as a raw material of the conductive particles.