JP2008276944A - Transparent conductive material, transparent conductive film, and formation method of transparent conductive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive transparent conductive material excelling in conductivity, and capable of stably forming a high-hardness transparent conductive film; a transparent conductive film; and a formation method of a transparent conductive film. <P>SOLUTION: This transparent conductive material has electric conductivity, and is characterized by containing, as constituents, an inorganic oxide (constituent A) having transparency in a visible range, and a film formation (constituent B) having a glass transition temperature Tg below 600°C, and having transparency in a visible range. The transparent conductive material is also characterized in that the inorganic oxide is an oxide forming a tolyltyl type crystalline structure, particularly a composite oxide forming a tolyltyl type crystalline structure containing antimony; and the film formation is glass powder having a refractive index (nd) above 1.55, and coming into a viscous state wetting the surface of the inorganic oxide below 600°C, or a resin cured by light irradiation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transparent conductive material that is highly useful as a material for a transparent conductive film that generates heat when energized or a transparent conductive film for a display device, a transparent conductive film, and a method for forming the transparent conductive film.

  In recent years, in heating films for anti-fogging or anti-icing of window glass of automobiles, aircraft, buildings, etc., and in conductive films of display elements such as liquid crystal display elements and electroluminescence (EL) display elements, it has become visible light. In contrast, an electrode material having high permeability is used.

  Conventionally, indium tin oxide (ITO) has been dominant as such a transparent conductive material. This is because indium tin oxide is excellent in transparency and conductivity, and the indium tin oxide film can be etched with a strong acid, and further has excellent adhesion to the substrate. As described above, indium tin oxide has excellent performance as a transparent conductive material, but has a drawback that it is expensive because the main raw material is indium and that the supply is not stable.

  Thus, for example, Patent Document 1 and Patent Document 2 propose a transparent conductive film using zinc oxide or tin oxide as a main material. However, the transparent conductive film containing zinc oxide as a main raw material has problems that the conductivity is not sufficient and sufficient performance cannot be obtained with respect to moisture and heat resistance. In addition, the transparent conductive film mainly composed of tin oxide has good heat resistance but is not suitable as a transparent electrode for high-definition displays because sufficient performance in etching processability cannot be obtained. There is a difficulty.

  These metal oxides can easily form a film on a substrate such as glass or ceramics to form a transparent conductive film. As a method for forming this transparent conductive film, the following method is known. That is, (1) vacuum deposition method, (2) sputtering method, (3) CVD method, and (4) coating method.

  However, the above methods (1), (2), and (3) are complicated and expensive, and have problems in cost and mass productivity. Further, although the method (4) has a possibility of solving the problems of the methods (1), (2), and (3), it is difficult to form a film that can withstand practical use. Met.

For example, a film obtained from an indium tin oxide sol composition produced by bringing an inorganic indium salt solution containing an inorganic tin salt into contact with an ion exchange resin has a large sheet resistance and is prone to pinholes. There is. In addition, when an organic solution of an inorganic compound such as indium nitrate, indium chloride, or stannic chloride is used, the formed film becomes cloudy or is easily scratched due to insufficient mechanical strength. There are disadvantages such as sticking.
Japanese Patent Laid-Open No. 3-50148 JP-A-8-171824

  SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and is inexpensive, excellent in conductivity, and capable of stably forming a transparent conductive film having high hardness, formation of a transparent conductive material, a transparent conductive film, and a transparent conductive film It is intended to provide a method.

  As a result of diligent research to solve the above-described problems, the present inventor has an electrical conductivity and transparency in the visible region, and a glass transition temperature Tg that softens at a relatively low temperature. A transparent conductive material composed of a low film-forming material is used as a paste dispersed using a dispersant, and this is applied to a substrate and baked to provide excellent conductivity and thermoelectric properties, and a highly conductive transparent conductive film. Inorganic oxides having a trityl-type crystal structure that can be formed at low cost and can be stably supplied as an inorganic oxide having electrical conductivity and transparency in the visible region can be formed. The inventors have found that the thermoelectric properties and transparency are excellent, and have completed the present invention.

  More specifically, the present invention provides the following.

  (1) An inorganic oxide (component A) having electrical conductivity and transparency in the visible region, and a film-formation product having a glass transition temperature Tg of 600 ° C. or lower and transparency in the visible region ( B component), a transparent conductive material.

  According to the aspect of (1), the transparent conductive film which consists of an inorganic oxide which has electroconductivity and has transparency in a visible region can be formed by baking or hardening of a comparatively low temperature. That is, the transparent conductive material has electrical conductivity and transparency in the visible range, and has a glass transition temperature Tg of 600 ° C. or less and transparency in the visible range. Is formed as a paste by dispersing with a dispersant (referred to as component C) and applied to a substrate such as glass or ceramics. By baking or curing, the inorganic oxide (A component) is bonded to each other by the film formed product (B component) to form a film. Further, since the film-formed product (component B) has a glass transition temperature Tg of 600 ° C. or lower, baking or curing can be performed at a low temperature of 600 ° C. or lower, decomposition of inorganic oxides due to high temperature, and deterioration of the substrate. There is no risk of strength reduction.

  Here, the film-formed product (component B) is a material for filling the gaps between the inorganic oxide fine particles and bonding the fine particles to form a film, for example, at a low temperature of 600 ° C. or lower. Glass powder that softens and wets the surface of the inorganic oxide to form a film by bonding the inorganic oxides together, a resin such as an organic binder that is cured by irradiation with light such as ultraviolet rays, etc. Mainly refers to a material having transparency and excellent surface hardness.

  (2) The transparent conductive material according to (1), wherein the inorganic oxide is an oxide having a trirutile crystal structure.

  (3) The transparent conductive material according to (2), wherein the inorganic oxide is a double oxide having a trityl-type crystal structure containing antimony.

According to aspects (2) and (3), since the inorganic oxide is an oxide having a trirutile crystal structure, the conductive film made of this inorganic oxide is excellent in electrical conductivity because it is excellent in electrical conductivity. In addition, exothermicity (hereinafter referred to as thermoelectric characteristics) is also excellent by energization. For this reason, it can be preferably used as a conductive film for display elements such as a heating resistor, a liquid crystal display element, and an electroluminescence (EL) display element for preventing fogging or anti-icing of window glass of automobiles and buildings. This is because trirutile crystals are connected by rutile chains (octahedral ridge-sharing straight chain) arranged in the [001] direction sharing adjacent straight-chain oxygen, and the S orbitals of the central ions of the oxygen octahedron. It is thought that this is because free electrons and holes propagate through the conduction band formed by. Examples of the trityl type crystal structure include a double oxide having a composition represented by MSb ₂ O ₆ (M is an element that becomes a divalent ion) containing an element that becomes a divalent ion and antimony, A double oxide having a composition represented by MIn ₂ O ₄ (M is an element that becomes a divalent ion) containing indium and an element that becomes an ion can be given. Examples of the element that becomes a divalent ion include Zn, Cd, Mg , Sb, Fe and the like. A trirutile crystal structure containing antimony is preferred from the viewpoints of electrical conductivity, thermoelectric properties, cost, and supply stability. In addition, as an element to be a divalent ion, Zn that can easily synthesize a trityl type crystal structure is preferable.

  (4) The transparent conductive material according to any one of (1) to (3), wherein the inorganic oxide is fine particles having an average particle diameter of 1 μm or less.

  According to the aspect of (4), since the inorganic oxide is fine particles having an average particle diameter of 1 μm or less, it is difficult to cause light scattering and a transparent conductive film can be obtained.

  (5) The film-formed product is a glass powder having a refractive index nd of 1.55 or more and a viscosity that wets the surface of the inorganic oxide at 600 ° C. or less. A transparent conductive material according to any one of the above.

  According to the aspect of (5), since the refractive index of the inorganic oxide can be made equal to that of the inorganic oxide, the interface reflection between the inorganic oxide and the film-formed product is reduced, and the transparency is excellent without reducing the transmittance. An electrically conductive film can be formed. In addition, since the conductive film can be formed by baking at a temperature of 600 ° C. or lower, there is no possibility of decomposing the inorganic oxide having electrical conductivity, so that the electrical conductivity is excellent. Further, there is no possibility of causing deterioration or strength reduction due to baking or the like on a substrate such as glass. The obtained conductive film has a high surface hardness.

  (6) The transparent conductive material according to any one of (1) to (4), wherein the film-formed product is a resin that is cured by light irradiation.

  According to the aspect of (6), since the film-formed product is a resin that is cured by light irradiation, it can be formed on the substrate by light irradiation such as ultraviolet rays without heating. For this reason, it is excellent in workability | operativity for film-forming. Moreover, there is no possibility that the inorganic oxide having electrical conductivity is decomposed, the base material is deteriorated or the strength is reduced. The obtained conductive film has a high surface hardness.

  (7) The transparent ratio according to any one of (1) to (6), wherein the ratio of the film formation to the inorganic oxide is 5 to 50% by weight of the film formation / the inorganic oxide × 100. Conductive material.

  According to the aspect of (7), since the electroconductivity of an inorganic oxide is not reduced with a film formation thing, the transparent conductive film excellent in electroconductivity and a thermoelectric characteristic is obtained. If the ratio is lower than the range, the bonding strength between the inorganic oxides is weakened, so that the mechanical strength tends to be lowered. If the ratio is higher, the contact between the inorganic oxides becomes insufficient, and the electrical conductivity tends to be lowered.

  (8) A transparent conductive paste comprising the transparent conductive material according to any one of (1) to (7) and a dispersant (component C).

  (9) The transparent conductive paste according to (8), wherein the dispersant is 5 to 50% by weight with respect to the total amount of the inorganic oxide and the film-formed product.

  According to aspects (8) and (9), a transparent conductive paste in which a transparent conductive material composed of an inorganic oxide and a film-formed product is uniformly dispersed by a dispersant is obtained.

  (10) A transparent conductive film obtained by applying the transparent conductive paste according to (8) or (9).

  According to the aspect of (10), the transparent conductive paste according to (8) or (9) has the transparency described in any of (1) to (7) and is excellent in conductivity. It consists of a transparent conductive material. For this reason, the conductive film formed by applying the transparent conductive paste has excellent conductivity and transparency.

  (11) The transparent conductive film according to (10), which has a surface resistivity of 200Ω or less.

  According to the aspect of (11), since surface resistivity is 200 ohms or less, it is excellent in electroconductivity.

  (12) Antifogging glass provided with the transparent conductive film as described in (10) or (11).

  According to the aspect of (12), since the transparent conductive film as described in (10) or (11) is excellent in electroconductivity and a thermoelectric characteristic, it is suitable as anti-fog glass of window glass, such as a motor vehicle and a building.

  (13) An inorganic oxide (component A) having electrical conductivity and transparency in the visible range, and a film-formation product having a glass transition temperature Tg of 600 ° C. or lower and transparency in the visible range ( B component) is added to a transparent conductive material comprising a dispersant (C component) to form a transparent conductive paste in which the inorganic oxide and the film-formed product are dispersed, and the obtained transparent conductive paste is used as a substrate. A method for forming a transparent conductive film, which comprises firing or curing after coating and drying.

  According to the aspect (13), it is possible to form a transparent conductive film that is inexpensive, excellent in conductivity, and has high hardness.

  The transparent conductive material of the present invention has transparency and is excellent in conductivity. The inorganic oxide constituting the transparent conductive material is preferably a double oxide having an antimony-containing trityl-type crystal structure, which can be supplied stably at low cost, and is particularly excellent in conductivity.

  A transparent conductive film formed by dispersing the transparent conductive material with a dispersant (component C) to form a paste, and applying and baking or curing the transparent conductive material on a substrate such as glass or ceramics is inexpensive. In addition to being excellent in conductivity and thermoelectric properties, it has high hardness and transparency.

  Further, since the film-formed product (component B) has a glass transition temperature Tg of 600 ° C. or lower, the transparent conductive material of the present invention can be fixed to the substrate at a low temperature of 600 ° C. or lower. For this reason, there is no possibility of causing decomposition of the inorganic oxide at a high temperature, deterioration of the substrate, reduction in strength, or the like.

  Hereinafter, the present invention will be specifically described.

  The transparent conductive material of the present invention has an electrical conductivity and transparency in the visible range, and has a glass transition temperature Tg of 600 ° C. or lower and transparency in the visible range. And a film-formed product (component B) containing

  The inorganic oxide is preferably an oxide having a trirutile crystal structure, more preferably a double oxide having a trirutile crystal structure containing antimony.

Further, film formation is preferably having a refractive index n _d of 1.55 or more, the glass powder as a viscous state to wet the surface of the inorganic oxide at 600 ° C. or less, or a resin which is cured by light irradiation It is characterized by being. The reason for limiting the refractive index to 1.55 in this case, since the refractive index n _d of the inorganic oxide to be created in this application is 1.55 or higher, by matching the refractive index of the film forming material and an inorganic oxide This is because it is easy to obtain a transparent material by suppressing interface scattering.

  In the present invention, high conductivity can be imparted to a material after baking or curing by an inorganic oxide having electrical conductivity and transparency in the visible region. In addition, the inorganic oxide is formed into a film shape by the inorganic oxides being bonded to each other by the film formation.

(Inorganic oxide (component A))
The inorganic oxide used in the present invention is not particularly limited as long as it has transparency, is electrically conductive, and has thermoelectric properties that generate heat when a voltage is applied. Examples include metal oxides such as antimony zinc oxide, antimony tin oxide, tin oxide, phosphorus-doped tin oxide, indium tin oxide, zinc aluminum oxide, and antimony pentoxide-zinc oxide, and in particular, excellent electrical conductivity. A double oxide having a trirutile crystal structure that is excellent in thermal electromotive rate and can be stably supplied at low cost, particularly a trirutile crystal structure containing antimony is more preferable. Furthermore, the one doped with Zn, which can easily synthesize one having a trirutile crystal structure, is most preferable. This trirutile-type crystal structure oxide is excellent in electrical conductivity and can be suitably used as a transparent conductive film that generates heat upon energization.

  This is because the inorganic oxide having a trirutile crystal structure is crystallized in such a way that rutile chains (octahedral ridge-sharing straight chain) arranged in the [001] direction are connected by sharing adjacent straight-chain oxygen. Turn into. It is considered that free electrons and holes propagate through the conduction band formed by the s orbital of the central ion of the oxygen octahedron.

  The average particle diameter of the inorganic oxide is preferably not more than the visible light wavelength. Exceeding the visible light wavelength is not preferable because the transparency of the transparent conductive film made of a transparent conductive material is significantly reduced. For this reason, the upper limit of the average particle size is preferably 1 μm or less, more preferably 0.4 μm or less, and most preferably 0.1 μm or less. On the other hand, when the crystal grains become small, they are affected by the crystal surface, and the alignment of the S orbitals in the crystal lattice tends to be incomplete. As a result, the electrical conductivity tends to decrease. For this reason, the lower limit of the average particle diameter is preferably 0.005 μm or more, more preferably 0.01 μm or more, and most preferably 0.05 μm or more.

(Film formation product (component B))
The film-formed product used in the present invention is not particularly limited as long as it is softened by heat treatment at a temperature of 600 ° C. or less, fills the gaps between the aggregated inorganic oxide fine particles, and forms a film by bonding with the fine particles. However, for example, glass powder having a glass transition temperature Tg of 600 ° C. or lower, a resin that is cured by light irradiation, and the like can be given.

The glass powder is not particularly limited as long as the glass transition temperature Tg is 600 ° C. or lower. For example, SiO ₂ —B ₂ O having a glass transition temperature Tg of 520 ° C. or lower and a refractive index nd of 1.55 or higher. _3- RO—Li ₂ O-based glass composition, SiO ₂ —B ₂ O ₃ —Bi ₂ O—RO ₃ —Rn ₂ O-based glass having a glass transition temperature Tg of 480 ° C. or less and a refractive index nd of 1.85 or more. Examples thereof include glass powders such as SiO ₂ —B ₂ O ₃ —TlO ₂ -based glass compositions having a composition, a glass transition temperature Tg of 400 ° C. or less, and a refractive index nd of 1.89 or more. Since these glass powders have a refractive index nd of 1.5 or more and can be approximately the same as the refractive index of the inorganic oxide, the refractive index between the inorganic oxide and the glass that is the film molding is low. Interfacial reflection due to the difference is suppressed and transparency is excellent. The refractive index n _d of the inorganic oxide is usually around 2.0.

  The upper limit of the average particle diameter of the glass powder is preferably 1 μm or less, more preferably 0.4 μm or less. If it exceeds 1 μm, the mixed state with the inorganic oxide is deteriorated, which is not preferable.

  The upper limit of the glass powder is preferably 50% by weight, more preferably 45% by weight, and most preferably 40% by weight, and the lower limit is preferably 40% by weight, based on the inorganic oxide. Is 5% by weight, more preferably 15% by weight, and most preferably 20% by weight. If it is less than 5% by weight, the strength of the conductive film after film formation is insufficient, and if it exceeds 50% by weight, it is conductive. Is not preferable because of drastically lowering.

  The resin that is cured by light irradiation includes at least a photoreactive compound such as a photoreactive monomer, a photoreactive oligomer, and a photoreactive polymer. Here, the term “reactive” means that when a photosensitive paste is irradiated with actinic rays, the reactive monomer, reactive oligomer, and reactive polymer are photocrosslinked, photopolymerized, photodepolymerized, photomodified, etc. It means that the chemical structure changes through the reaction of

  The photoreactive compound preferably contains a copolymer having a carboxyl group. Examples of the copolymer having a carboxyl group include, for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetic acid or a carboxylic acid-containing monomer such as these acid anhydrides and methacrylic acid ester, acrylic acid. Examples thereof include those obtained by selecting monomers such as acid ester, styrene, acrylonitrile, vinyl acetate, 2-hydroxyacrylate, and copolymerizing using an initiator such as azobisisobutyronitrile.

  Moreover, as a copolymer which has a carboxyl group, the copolymer which uses (meth) acrylic acid ester and (meth) acrylic acid as a copolymerization component is used preferably. In particular, a styrene / methyl methacrylate / methacrylic acid copolymer is preferably used.

  Furthermore, it is also preferable that the copolymer having a carboxyl group has an ethylenically unsaturated group in the side chain. Examples of the ethylenically unsaturated group include an acryl group, a methacryl group, a vinyl group, and an allyl group. The method for adding such a side chain to the copolymer is to use an ethylenically unsaturated compound or acrylic acid chloride having a glycidyl group or an isocyanate group with respect to the mercapto group, amino group, hydroxyl group or carboxyl group in the copolymer. There is a method in which methacrylic acid chloride or allyl chloride is subjected to an addition reaction.

  Here, as the ethylenically unsaturated compound having a glycidyl group, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, glycidyl ethyl acrylate, crotonyl glycidyl ether, glycidyl crotonic acid, glycidyl ether of isocrotonic acid and the like can be mentioned. . Examples of the ethylenically unsaturated compound having an isocyanate group include (meth) acryloyl isocyanate and (meth) acryloylethyl isocyanate. In addition, ethylenically unsaturated compounds having a glycidyl group or an isocyanate group, acrylic acid chloride, methacrylic acid chloride or allyl chloride are added in an amount of 0.05 to 1 mol with respect to a mercapto group, amino group, hydroxyl group or carboxyl group in the polymer. It is preferable to add an equal amount. Moreover, it is preferable that the addition amount of the copolymer which has a carboxyl group is 10 to 90 weight% in the organic component except a solvent at the point that an appropriate exposure amount can be obtained.

  The refractive index of the photoreactive compound is not particularly limited, but the refractive index of the cured material is too low, and the refractive index of the resin after curing is preferably 1.48 or more, 1.55 or more, and 1. More preferably, it is in the range of 80 or less. As a result, the refractive index is substantially the same as the refractive index of the inorganic oxide, so that the transparency is further improved.

  The photoreactive compound can further contain a photopolymerization initiator. Any photopolymerization initiator may be used as long as it has a polymerization initiating ability upon ultraviolet irradiation. Used from those that generate radical species. Specifically, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane- Acetophenone-based initiators such as 1-one and 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one; benzoin, 2,2-dimethoxy-1, Benzoin initiators such as 2-diphenylethane-1-one; benzophenone, [4- (methylphenylthio) phenyl] phenylmethanone, 4-hydroxybenzophenone, 4-phenylbenzophenone, 3,3 ′, 4,4 ′ -Benzophenone-based initiators such as tetra (t-butylperoxycarbonyl) benzophenone; 2-chlorothioxa Tons, can be mentioned thioxanthone initiators such as 2,4-diethyl thioxanthone. In particular, it is preferable to use an initiator having absorption at a relatively long wavelength. These can be used alone or as a mixture. Depending on the type of polymerization initiator, a method may be used in which a reaction accelerator such as a tertiary amine such as p-dimethylaminobenzoic acid ethyl ester or p-dimethylaminobenzoic acid isoamyl ester is added. The blending ratio of the polymerization initiator is preferably 0.05 to 20 parts by weight, more preferably 0.1 to 20% by weight with respect to 100 parts by weight of the curable component in the resin. By setting the addition amount of the photopolymerization initiator within this range, good photosensitivity can be obtained.

  Moreover, a sensitizer can be used together with a photopolymerization initiator to improve sensitivity and to expand the effective wavelength range for the reaction. Specific examples of the sensitizer include benzophenone, methyldicyanobenzene, benzal and the like. Some sensitizers can also be used as photopolymerization initiators. The addition amount of the sensitizer is preferably 0.05 to 20% by weight, more preferably 0.1 to 20% by weight, based on the total amount of the organic components excluding the solvent. By setting the addition amount of the sensitizer within this range, good photosensitivity can be obtained.

  In the present invention, it is more preferable to add an ultraviolet absorber. By adding an ultraviolet absorber, scattered light inside the paste due to exposure light can be absorbed and scattered light can be weakened. Thereby, a finer pattern can be formed sharply. As the ultraviolet absorber, those composed of organic dyes are preferably used. The addition amount of the ultraviolet absorber is preferably 0.001 to 2% by weight, more preferably 0.01 to 1% by weight, based on the total amount of the organic components excluding the solvent. This is because, within this range, the transmission limit wavelength and the wavelength inclination width are kept within the desired ranges, and the effect of absorbing scattered light can be obtained while maintaining the transmittance of exposure light and the sensitivity of photosensitivity.

  In addition, due to the difference in refractive index between the dispersed inorganic oxide fine particles and the resin, it is difficult to avoid light scattering inside the paste due to exposure light. ) Are likely to occur, and influence is more likely to occur in a finer and finer pattern. Therefore, you may add the polymerization inhibitor which can suppress the photoreaction with respect to weak light like scattered light.

(Dispersant (component C))
The transparent conductive material of the present invention is applied to the substrate by dispersing the transparent conductive material with a dispersant (component C) and preparing it in a paste form. Examples of the dispersant used in the present invention include methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone, dioxane, acetone, cyclohexanone, cyclopentanone, isobutyl alcohol, isopropyl alcohol, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, bromobenzene, An organic solvent mixture containing one or more of chlorobenzene, dibromobenzene, dichlorobenzene, bromobenzoic acid, chlorobenzoic acid and the like can be mentioned.

  Additive components such as photoacid generators, photobase generators, sensitization aids, plasticizers, thickeners, organic solvents, acids, bases, antisettling agents, and antioxidants can be added as necessary. it can.

  For example, when a binder component is required, as a polymer, for example, polyvinyl alcohol, polyvinyl butyral, methacrylic acid ester polymer, acrylic acid ester polymer, acrylic acid ester-methacrylic acid ester copolymer, butyl methacrylate resin, etc. Can be used.

(Preparation of transparent conductive paste)
The transparent conductive material comprising the inorganic oxide (A component) and the film molded product (B component) of the present invention is blended with the dispersant (C component) and homogeneously mixed and dispersed into a transparent conductive paste. Prepared.

The transparent conductive paste is preferably 5 to 50% by weight, more preferably 10 to 10%, based on the total amount of the inorganic oxide (component A) and the film-formed product (component B) which are the transparent conductive material of the present invention. 45% by weight of the dispersant (component C) is added, and the mixture is uniformly mixed and dispersed with a three-roller or a kneader.
When an inorganic oxide having a trityl type crystal structure is made into a paste using a dispersant or the like, rutile chains arranged in the [001] direction (octahedral ridge-sharing straight chain) must share adjacent straight-chain oxygen. Agglomerate as linked by

  The viscosity of the transparent conductive paste is appropriately adjusted depending on the addition ratio of the inorganic oxide (component A), film-forming product (component B), dispersant (component C), other additives, etc., but the range is usually Is 100,000 to 200,000 cps (centipoise). For example, when the application to the substrate is performed by a spin coating method, a dip coating method, or a spray method, 10 to 5000 cps is preferable. When the screen printing method is used, 5000 to 200,000 cps is preferable. When using a blade coater method, a die coater method, etc., 5000-50,000 cps is preferable.

(Formation of transparent conductive film)
A transparent conductive film can be obtained by applying the transparent conductive paste thus obtained to a transparent substrate such as glass and further curing or heat-treating it. The obtained transparent conductive film is a heating resistor for preventing fogging or anti-icing of window glass of automobiles, aircrafts, buildings, etc., display elements such as liquid crystal display elements, electroluminescence (EL) display elements, etc. It can be preferably used to form an electrode.

  Here, the thickness of the transparent conductive layer formed by applying the transparent conductive paste to the substrate is preferably 0.05 to 20 μm. If the thickness is less than 0.05 μm, it is difficult to obtain sufficient conductivity, and if it exceeds 20 μm, problems such as a decrease in transparency occur, which is not preferable.

  And in order to form this transparent conductive layer, in the case where the transparent conductive layer is a transparent conductive paste prepared using glass powder as a film molded product (component B), the transparent conductive paste applied to the substrate The layer is dried to volatilize the dispersant (component C), and then fired in a firing furnace. The glass powder softens, wets the surface of the inorganic oxide, fills the gaps between the aggregated inorganic oxide fine particles, and bonds with the fine particles to form an inorganic oxide conductive film. The firing atmosphere and temperature vary depending on the type of paste and substrate, but firing is performed in an atmosphere of air, nitrogen, hydrogen, or the like. As the firing furnace, a batch-type firing furnace or a belt-type continuous firing furnace can be used.

  The firing temperature is preferably 600 ° C. or lower, more preferably 550 ° C. or lower, and it is usually preferable to perform firing while maintaining for 30 to 120 minutes. Thus, a transparent conductive film is produced on the surface of the substrate.

  On the other hand, in the case of a transparent conductive paste prepared using a resin that is cured by light irradiation as a film molded product (component B), light is irradiated to the layer of the transparent conductive paste applied to the substrate using an exposure device. To cure the resin. A proximity exposure machine or the like can be used as the exposure apparatus. Moreover, when performing exposure of a large area, a large area can be exposed with an exposure machine having a small exposure area by applying the transparent conductive paste of the present invention on a substrate and then performing exposure while transporting. . In this way, the photoreactive compound filling the gaps between the aggregated inorganic oxide fine particles is photocured and bonded to the inorganic oxide fine particles to form an inorganic oxide conductive film.

The transparent conductive film made of the transparent conductive material of the present invention can have a surface resistance value of 200Ω or less, more preferably 100Ω or less. If it exceeds 200Ω, the conductivity and thermoelectric properties are not sufficient, and the antistatic effect is also deteriorated, which is not preferable. The surface resistance value is determined in advance by measuring a surface resistance measurement point of the transparent conductive film, and a constant current is passed to the measurement point by a four-probe type surface resistance measuring instrument. Is measured and calculated.
The transparent conductive film may be formed on the entire surface of the substrate or may be partially formed with a certain pattern. Furthermore, the transparent conductive film preferably has a pair of electrode members formed on at least a part of the transparent conductive film. The electrode member is preferably a metal or alloy such as Au, Ag, or Cu, which has a sufficiently lower resistance than the transparent conductive film.

  Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited to these examples.

[Example 1]
Zinc oxide (ZnO) and antimony oxide (Sb ₂ O ₃ ) were weighed in an equimolar amount and mixed well in a mortar to obtain a mixed powder.

The obtained mixed powder was calcined by holding at 820 ° C. for 20 hours under atmospheric pressure, and then allowed to cool and preliminarily calcined. Then, the pre-fired fired body is pulverized, and the powder obtained by pulverization is held at 1040 ° C. for 40 hours under atmospheric pressure and fired, and then allowed to cool to obtain a temporary fired body. The calcined body was further pulverized and again fired by holding at 1040 ° C. for 40 hours, and then allowed to cool and calcined. The fired body was further pulverized into inorganic oxide (ZnSb ₂ O ₆ ) fine particles having an average particle diameter of 0.1 μm or less.

The obtained inorganic oxide (ZnSb ₂ O ₆ ) fine particles were subjected to X-ray diffraction (XRD), and structural analysis was performed from the obtained diffraction patterns. As a result, the crystal lattice constant was a = 4.666 angstroms and c = 9.265 angstroms with a tetragonal trirutile crystal structure.

Next, an inorganic oxide (ZnSb ₂ O ₆₎ fine particles obtained, the glass powder (refractive index _{n d} 1.895, a glass transition temperature Tg of _{400 ℃, SiO 2 -B 2 O} 3 -Tl 2 O Glass powder having an average particle size of 0.4 μm, the composition ratio of which is mass% based on oxide, SiO ₂ is 52%, B ₂ O ₃ is 14%, Tl ₂ O is 33%, Glass Phys -Chem.-USSR Vol.012 (1986) P.0334) and methyl ethyl ketone mixed so that the transparent conductive material after volatilization of methyl ethyl ketone is 40 vol% A transparent conductive paste was prepared.

  The obtained transparent conductive paste was applied to a 5 cm square glass substrate by spin coating, and after volatilizing methyl ethyl ketone, the rotation speed was adjusted so that the film thickness became 5 μm. A transparent conductive film was obtained by baking at 30 ° C. for 30 minutes.

  The electrical conductivity σ of the obtained transparent conductive film was measured at room temperature. That is, the surface resistance measurement point of the transparent conductive film was determined in advance, and this measurement point was measured by a four-probe method using a digital multimeter (Caseley's 2001 type multimeter). As a result, it was confirmed that the surface resistivity was 100Ω and the conductivity was excellent.

[Example 2]
Volatilization of methyl ethyl ketone with inorganic oxide (ZnSb ₂ O ₆ ) fine particles prepared in Example 1, acrylic monomer (1 wt% of UV curing agent added to an equal mixture of methyl methacrylate and polyethylene glycol dimethacrylate) and methyl ethyl ketone What was prepared so that the latter transparent conductive material might become 20 vol% was mixed, and the transparent conductive paste was produced.

  The obtained transparent conductive paste was applied to a 5 cm square glass substrate by spin coating, and after volatilizing methyl ethyl ketone, the rotation speed was adjusted so that the film thickness became 5 μm, and this was irradiated with UV to irradiate the transparent conductive film Got.

  The electrical conductivity σ of the obtained transparent conductive film was measured by the same method as in the examples. As a result, it was confirmed that the surface resistivity was 120Ω and the conductivity was excellent.

Claims (13)

  An inorganic oxide (A component) having electrical conductivity and transparency in the visible range, and a film-formation product (B component) having a glass transition temperature Tg of 600 ° C. or lower and transparency in the visible range And a transparent conductive material.   The transparent conductive material according to claim 1, wherein the inorganic oxide is an oxide having a trirutile crystal structure.   The transparent conductive material according to claim 2, wherein the inorganic oxide is a double oxide having a trirutile crystal structure containing antimony.   The transparent conductive material according to claim 1, wherein the inorganic oxide is fine particles having an average particle diameter of 1 μm or less.   The transparent film according to any one of claims 1 to 4, wherein the film-formed product is a glass powder having a refractive index nd of 1.55 or more and a viscosity that wets the surface of the inorganic oxide at 600 ° C or less. Conductive material.   The transparent conductive material according to claim 1, wherein the film-formed product is a resin that is cured by light irradiation.   The transparent conductive material according to any one of claims 1 to 6, wherein a ratio of the film formation to the inorganic oxide is 5 to 50% by weight of the film formation / the inorganic oxide × 100.   A transparent conductive paste comprising the transparent conductive material according to claim 1 and a dispersant (component C).   The transparent conductive paste according to claim 8, wherein the dispersant is 5 to 50 wt% with respect to the total amount of the inorganic oxide and the film-forming product.   The transparent conductive film formed by apply | coating the transparent conductive paste of Claim 8 or 9.   The transparent conductive film according to claim 10, wherein the surface resistivity is 200Ω or less.   The anti-fog glass provided with the transparent conductive film of Claim 10 or 11.   An inorganic oxide (A component) having electrical conductivity and transparency in the visible region, and a film-formation product (B component) having a glass point transfer Tg of 600 ° C. or less and having transparency in the visible region. And adding a dispersant (component C) to the transparent conductive material comprising a transparent conductive paste in which the inorganic oxide and the film forming material are dispersed, and applying the obtained transparent conductive paste to a substrate. A method of forming a transparent conductive film, characterized by baking or curing after drying.