JP2008140559A - Translucent conductive paint and translucent conductive membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a translucent conductive paint capable of forming a translucent conductive membrane superior in translucency and conductivity, and the translucent conductive membrane superior in translucency and conductivity formed by using this translucent conductive paint. <P>SOLUTION: The translucent conductive paint contains two kinds of conductive oxide needle-like powders A and B composed of indium oxide doped by metal oxide. As for the powder A, the specific surface area is 4 to 20 m<SP>2</SP>/g, and powder colors in an L<SP>*</SP>a<SP>*</SP>b<SP>*</SP>color system L<SP>*</SP>=82 to 91, a<SP>*</SP>=-8 to 2, and b<SP>*</SP>=0 to 10. As for the powder B, the specific surface area is less than 4 m<SP>2</SP>/g, and the powder colors are L<SP>*</SP>=82 to 91, a<SP>*</SP>=-8 to 2, b<SP>*</SP>=15 to 20. Moreover, the weight ratio of the powder A and the powder B is A:B=35:65 to 20:80. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a translucent conductive coating applied to, for example, the formation of a transparent electrode of a dispersive electroluminescent element (dispersed EL element), and in particular, has excellent translucency and conductivity, and the film is colored. The present invention relates to a translucent conductive paint to be prevented and a translucent conductive film.

  A translucent conductive film applied to a transparent electrode or the like of an EL element is formed by applying a translucent conductive paint in which a conductive filler is dispersed in a solvent containing a binder. Conventionally, as the conductive filler of the translucent conductive paint, oxidation of indium-tin oxide (hereinafter sometimes referred to as ITO), tin-antimony oxide (hereinafter sometimes referred to as ATO), etc. Physical fillers are used, and ITO is the most excellent because of its lower resistance than ATO.

  In the translucent conductive paint, the smaller the content of the conductive filler, the better. The reason is that the light absorption of the oxide as the conductive filler is far greater than that of the transparent resin (binder) which is one of the paint components. Therefore, as long as a conductive film having a low resistance value is obtained, the light transmittance of the conductive film can be improved by using as little oxide filler as possible with respect to the transparent resin. For these reasons, compared to spherical or granular conductive fillers, needle-shaped or flake-shaped conductive fillers can provide a low-resistance film with a small amount of addition, so that cost, film strength, and weather resistance are improved. Excellent in terms of properties.

  As a method for obtaining the above oxide powder in the form of flakes, a colloidal solution such as an inorganic oxide or a hydrous inorganic oxide is frozen, and an inorganic oxide particle or a hydrous hydroxide is placed between the crystal planes of the solvent of the colloidal solution. A method is known in which product particles are precipitated, dried to remove the solvent, and in the case of a hydrated oxide, it is further roasted and manufactured (Patent Document 1: Japanese Patent Application Laid-Open No. Sho 62-3003).

  The acicular oxide powder can be obtained by thermally decomposing acicular tin oxalate to obtain acicular tin oxide (Patent Document 2: Japanese Patent Laid-Open No. 56-120519), indium nitrate. Proposed is a method of thermally decomposing white acicular indium compound powder recovered from a high-temperature heat-concentrated slurry of the present invention to obtain acicular indium-tin oxide powder (Patent Document 3: JP-A-6-293515). Yes.

  In particular, the indium-tin oxide (ITO) needle-like powder obtained by the method of Patent Document 3 is considered to be most preferable because it can realize excellent conductivity and transparency as a translucent conductive film. As for the indium-tin oxide (ITO) needle-like powder obtained by the method described in Patent Document 3, a translucent conductive paint (conductive paste) and a translucent conductive film in which this is applied as a conductive filler are also available. It has already been proposed (Patent Document 4: JP-A-6-309922).

  However, in the method for obtaining the ITO needle-shaped powder described in Patent Document 3, a tin compound is added to a high-temperature concentrated slurry of indium nitrate to obtain a tin-containing white needle-shaped indium compound powder. Since the ITO needle powder is formed by baking, it is difficult to control the amount of tin oxide dope and is not suitable for mass production.

  For this reason, most of the ITO needle powders that are actually used are obtained by collecting white needle-like indium compound powder from a high-temperature heat-concentrated slurry of indium nitrate and calcining it in the atmosphere to produce needle-like indium oxide powder. Obtained (Patent Document 5: JP-A-6-293516), then, a method of doping the indium oxide needle-like powder with tin oxide (Patent Document 6: JP-A-6-293517, Patent Document 7: (Japanese Patent Laid-Open No. 10-17326).

  By the way, in the method described in the said patent document 6 or the patent document 7, in order to make the doped tin oxide component dissolve in indium oxide later, it is necessary to perform a baking process. As for the temperature condition of this baking treatment, it is said that an arbitrary temperature of 700 ° C. or higher can be selected. However, in actuality, it is necessary to completely dissolve the tin oxide component in indium oxide to make it highly conductive. The firing process is performed at an extremely high temperature of 1300 ° C.

Although the conductivity of the ITO needle-like powder can be sufficiently increased by such a high-temperature baking treatment, the primary particles in the ITO needle-like powder are about 0.25 to 1.0 μm (specific surface area conversion). The grain size grows to about 3 to 0.8 m ² / g), and there is a problem that the ITO needle-like powder is colored yellow-green.

  Moreover, when the translucent conductive paint to which this ITO needle-like powder is applied is used, the formed translucent conductive film is colored yellow-green. When the translucent conductive film is colored yellow-green, for example, when this translucent conductive film is applied to a transparent electrode of a dispersion type EL element, the emission color of the EL element is the light emission of the original phosphor. There was a problem that the phenomenon of being different from the color occurred.

  As a means for solving this problem, in the production process of ITO needle-shaped powder, the firing temperature is lowered than before, for example, firing at about 500 to 900 ° C., and controlling the reducing conditions, the color of the ITO needle-shaped powder is changed. A method of making the color close to white (neutral) (Patent Document 8: Japanese Patent Application Laid-Open No. 2005-322626) has been proposed, whereby the coloring problem of the ITO needle-shaped powder is improved.

JP-A-62-23003 JP-A-56-120519 JP-A-6-293515 JP-A-6-309922 JP-A-6-293516 JP-A-6-293517 Japanese Patent Laid-Open No. 10-17326 JP 2005-322626 A

  In the translucent conductive paint using the above-mentioned low-temperature fired ITO needle-shaped powder, when the thickness of the obtained translucent conductive film is increased, it is obtained by the translucent conductive paint of the high-temperature fired ITO needle-shaped powder. There was a problem that the surface resistance value was higher than that of the translucent conductive film. On the other hand, in the case of a light-transmitting conductive paint using an ITO needle-shaped powder subjected to high-temperature baking treatment, the surface resistance value rapidly increases as the film thickness of the light-transmitting conductive film obtained becomes thin along with the above-described coloring problem. There was a problem.

  The present invention has been made paying attention to such problems of the prior art, and a translucent conductive paint that enables the formation of a translucent conductive film that is more excellent in translucency and conductivity than the prior art. It is another object of the present invention to provide a translucent conductive film excellent in translucency and conductivity by using this translucent conductive paint.

  In order to achieve the above object, the present inventor has examined the manufacturing conditions of the conductive oxide needle-shaped powder in detail, and as a result, when firing the indium oxide needle-shaped powder doped with tin oxide, It has been found that by combining the fired powder, it is possible to form a light-transmitting conductive film excellent in light-transmitting property and conductivity, and the present invention has been completed.

That is, the translucent conductive paint provided by the present invention is the translucent conductive paint in which a conductive oxide needle-like powder made of indium oxide doped with a metal oxide is dispersed in a solvent containing a binder. Conductive oxide needle-shaped powder has a specific surface area of 4 to ²⁰ m ² / g and a powder color (light source: D65, viewing angle: 10 °) in the L ^* a ^* b ^* color system L ^* = 82 to 91 , A ^* = − 8 to 2 and b ^* = 0 to 10, conductive oxide needle-shaped powder A, powder surface color in L ^* a ^* b ^* color system with a specific surface area of less than 4 m ² / g Conductive oxide needle-like powder B with (light source: D65, viewing angle: 10 °) L ^* = 82 to 91, a ^* = − 8 to 2, b ^* = 15 to 20, and conductive oxidation The weight ratio between the needle-like powder A and the conductive oxide needle-like powder B is A: B = 35: 65 to 20:80. And features.

  In the translucent conductive paint according to the present invention, the conductive oxide needle-shaped powder A has a lattice constant of 1.0118 to 1.0120 nm, and the conductive oxide needle-shaped powder B has a lattice constant. Is 1.021 to 1.0123 nm. Further, the aspect ratio of the conductive oxide needle-shaped powder A and the conductive oxide needle-shaped powder B is preferably 5 or more.

  In the translucent conductive paint of the present invention, the metal oxide doped into indium oxide can be at least one selected from tin oxide, zirconium oxide, zinc oxide, tungsten oxide, and titanium oxide. In the translucent conductive paint of the present invention, the weight ratio of the conductive oxide needle-shaped powder and the binder is preferably in the range of conductive oxide needle-shaped powder: binder = 40: 60 to 90:10.

  The present invention also provides a translucent conductive film formed using the above-described translucent conductive paint of the present invention. The surface resistance of the translucent conductive film is such that the transmittance is 72%. It is 1000Ω / □ (ohms per square) or less and 10000Ω / □ (ohms per square) or less at a transmittance of 81%.

  According to the present invention, a translucent conductive film excellent in both translucency and conductivity regardless of the film thickness can be obtained, and a translucent conductive paint used for forming this excellent translucent conductive film is obtained. Can be provided. Therefore, by applying the translucent conductive film according to the present invention to the transparent electrode of the dispersion type EL element, a high-performance EL element having excellent transparency and conductivity can be obtained.

  About two types of conductive oxide needle-like powder applied to the translucent conductive paint according to the present invention, a conductive oxide needle-like powder composed of indium oxide doped with tin oxide (ITO needle-like powder) Will be described in detail in comparison with the prior art.

First, the manufacturing method of electroconductive oxide needle-shaped powder is demonstrated. After indium metal is dissolved in nitric acid, it is heated and concentrated at a liquid temperature of 130 to 150 ° C. to evaporate water and nitric acid from the system to form a thick white slurry. The white slurry is filtered at a high temperature and then washed with a large amount of pure water to obtain a white acicular indium compound powder. This white acicular indium compound powder is considered to be a basic nitrate of indium, and usually contains about 55 to 68% by weight of In and about 5 to 23% by weight of NO ₃ ⁻ .

  The white acicular compound powder is calcined at 300 ° C. or higher in the air to obtain indium oxide acicular powder. The obtained indium oxide needle-like powder consists of needle-like secondary particles composed of primary particles having an average particle diameter of about 0.01 to 0.07 μm, and pores are formed between the primary particles. ing.

  Next, after condensing tin tetrachloride into capillaries in the pores of the indium oxide needle powder, it is hydrolyzed at atmospheric humidity and baked, thereby conducting a conductive material composed of indium oxide doped with tin oxide. Oxide needle-like powder (hereinafter also referred to as ITO needle-like powder) is obtained. The tin content in the ITO needle-like powder is preferably 1 to 12% by weight, and more preferably 2 to 10% by weight, from the viewpoint of conductivity.

In the firing step, after firing at 1000 to 1300 ° C. according to the method described in Patent Document 7, the specific surface area is less than 4 m ² / g by performing reduction treatment in a reducing gas atmosphere, and L ^{* A *} b ^* Conductive oxidation in which the powder color (light source: D65, viewing angle: 10 °) in the color system is L ^* = 82 to 91, a ^* = − 8 to 2, and b ^* = 15 to 20 A needle-like powder (ITO needle-like powder) B is obtained. The lattice constant of the conductive oxide needle-like powder B obtained by this method is in the range of 1.021 to 1.0123 nm.

Further, in the firing step, according to the method described in Patent Document 8, the firing temperature is set to about 500 to 900 ° C., and the reducing gas conditions (hydrogen, alcohol, etc.) under the reduction conditions of the ITO needle-like powder obtained. By adjusting the gas flow rate, processing temperature, processing time, etc., the specific surface area is 4-20 m ² / g and the powder color in the L ^* a ^* b ^* color system (light source: D65, viewing angle: 10 °) is a conductive oxide needle-like powder (ITO needle-like powder) A in which L ^* = 82 to 91, a ^* = − 8 to 2, and b ^* = 0 to 10. The lattice constant of the conductive oxide needle-shaped powder A is in the range of 1.0118 to 1.0120 nm.

The conductive oxide needle powders A and B have a specific resistance (hereinafter referred to as dust resistance) when a pressure of 980 Pa (100 kgf / cm ² ) is applied to form a pellet. In A, about 0.02 to 0.2 Ω · cm is obtained, and it is preferably controlled within the range of 0.02 to 0.12 Ω · cm. In addition, the ITO needle-like powder B has a compacting resistance of about 0.01 to 0.1 Ω · cm, and is preferably controlled within the range of 0.01 to 0.05 Ω · cm.

  In general, it is preferable that the conductive oxide needle-shaped powder composed of indium oxide doped with a metal oxide has an aspect ratio of 5 or more because sufficient conductivity can be obtained with a small amount of powder with respect to the binder. . If the aspect ratio is less than 5, it is difficult to reduce the specific resistance of the translucent conductive film to 5.0 Ω · cm or less if the addition of powder is small. The aspect ratio is preferably high and more preferably 10 or more. The above-mentioned conductive oxide needle-shaped powders A and B can both have a major axis (length) of about 5 to 300 μm, an aspect ratio of 5 or more, and an aspect ratio of about 30 depending on the concentration conditions. .

  Although there is no restriction | limiting in particular regarding the major axis (length) of electroconductive oxide needle-shaped powder, 1-300 micrometers is preferable and 5-100 micrometers is still more preferable. This is because the larger the major axis, the smaller the number of contacts between the particles and the lower the resistance. For example, when used in a dispersion-type EL element, the phosphor layer on the coated surface uses zinc sulfide particles having a diameter of 5 to 30 μm, and thus there are irregularities of about several μm on the surface. Therefore, when the major axis is 1 μm or more, the contact between the acicular particles is maintained even when such irregularities exist, and the necessary conductivity is obtained.

  On the other hand, if the major axis exceeds 300 μm, it may be difficult to pass through the screen mesh during screen printing, which may hinder printing. Generally, a long diameter of 100 μm or less is preferable. However, this is not the case when printing is performed using a coarse screen of 100 mesh or less. Although the translucent conductive paint according to the present invention has a relatively large major axis (length), it is possible to screen-print lines having a width of about 200 μm.

  In addition, in the manufacturing method of the above-described conductive oxide needle-shaped powder, examples of the metal oxide doped into indium oxide include zirconium oxide, zinc oxide, tungsten oxide, titanium oxide and the like in addition to the tin oxide. These can be used alone or in combination. In addition, the conductive oxide needle-shaped powder in the present invention forms a needle-shaped hydroxide by a production method other than the above-described method, for example, a uniform precipitation method using urea from a solution of indium nitrate and tin nitrate. It is possible to obtain a powder having a major axis (length) of about 1 to 5 μm by a method of calcining hydroxide.

  Next, the manufacturing method of the translucent conductive paint which concerns on this invention is demonstrated. First, the conductive oxide needle-shaped powders A and B are mixed with a binder and a solvent, and after adding a dispersant or the like as necessary, a dispersion treatment is performed. At that time, the ratio (weight ratio) between the conductive oxide needle-shaped powder A and the conductive oxide needle-shaped powder B is set to a range of A: B = 35: 65 to 20:80. Outside this range, good conductive properties cannot be obtained, and particularly when the ratio of the conductive oxide needle-like powder B is high, the translucent conductive film is colored, which is not preferable.

  The weight ratio of the conductive oxide needle-shaped powder to the binder in the translucent conductive paint is preferably in the range of conductive oxide needle-shaped powder: binder = 40: 60 to 90:10, 60:40 to 80 : 20 is more preferable. When there is more binder than 40:60 with the said conductive oxide needle-shaped powder: binder, the resistance of the translucent conductive film obtained may become too high, and conductive oxide needle-shaped powder: 90% with a binder. When the binder is less than 10, not only the strength of the light-transmitting conductive film is lowered, but also the contact between the acicular particles is insufficient and the conductivity is lowered.

  As a binder used for a translucent conductive paint, it is possible to use an inorganic binder and an organic binder conventionally used for a translucent conductive film. For example, thermoplastic resins such as acrylic and polyester, thermosetting resins such as epoxy and urethane, acrylic, urethane, and epoxy ultraviolet curable resins can be used.

  In addition, the solvent used for the light-transmitting conductive paint can be appropriately selected in consideration of solubility in the plastic substrate to be used and film formation conditions. For example, alcohol solvents such as methanol (MA), ethanol (EA), 1-propanol (NPA), isopropanol (IPA), butanol, pentanol, benzyl alcohol, diacetone alcohol (DAA), acetone, methyl ethyl ketone (MEK) , Ketone solvents such as methyl propyl ketone, methyl isobutyl ketone (MIBK), cyclohexanone and isophorone, ester solvents such as ethyl acetate, butyl acetate and methyl lactate, ethylene glycol monomethyl ether (MCS), ethylene glycol monoethyl ether (ECS) ), Ethylene glycol isopropyl ether (IPC), propylene glycol methyl ether (PGM), propylene glycol ethyl ether (PE), propylene glycol methyl ether Diacetate (PGM-AC), propylene glycol ethyl ether acetate (PE-AC), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether , Glycol derivatives such as diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, formamide (FA), N-methylformamide Dimethylformamide (DMF), dimethylacetamide, dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, ethylene glycol, diethylene glycol, toluene, xylene, tetrahydrofuran (THF), chloroform, mesitylene, Examples thereof include, but are not limited to, benzene derivatives such as dodecylbenzene.

  Examples of the dispersant include various coupling agents such as a silicon coupling agent, various polymer dispersants, anionic, nonionic, and cationic surfactants. These dispersants are appropriately selected according to the type of conductive oxide needle powder used and the dispersion treatment method. For the dispersion treatment, general-purpose methods such as ultrasonic treatment, homogenizer, paint shaker, bead mill, and three roll mill can be applied.

  The translucent conductive paint of the present invention can form a translucent conductive film by applying the translucent conductive paint on a substrate by an ordinary method. As a method for applying the light-transmitting conductive paint, a screen printing method, a gravure printing method, a wire bar coating method, a doctor blade coating method, a roll coating method, or the like can be used.

  The translucent conductive film of the present invention thus obtained is composed of the above-mentioned two kinds of conductive oxide needle-like powders, so that it is possible to suppress the coloring of the film and at the same time, regardless of the film thickness. It has translucency and conductivity. Specifically, the surface resistance value of the translucent conductive film of the present invention is 1000Ω / □ (ohms per square) or less at a transmittance of 72%, and 10000Ω / □ (ohms) at a transmittance of 81%.・ Per-square) or less, and has both high translucency and conductivity.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the following description, “%” indicates “% by weight” excluding% of transmittance and haze value.

The particle size of the powder was measured with a scanning electron microscope manufactured by JEOL Co., Ltd. The average pore diameter, pore volume, and specific surface area between primary particles were measured using a Quantasorb QS-10 manufactured by Quantachrome. For the lattice constant of the powder, wide angle X-ray diffraction measurement (Si standard powder: ITO needle powder [weight ratio] = mixed at a blending ratio of 30:70 to 40:60) was performed using NIST Si standard powder as an internal standard. Then, it was determined by Rietveld analysis. Powder resistance, after insertion the powder to a dedicated holder electrode cross-sectional area 2 cm ^2, by applying a predetermined pressure (100kgf / cm ^2), was determined by measuring the inter-electrode resistance.

The powder color of the conductive oxide needle-like powder and the film color of the translucent conductive film in the L ^* a ^* b ^* color system were measured using a simple spectral color difference meter NF333 manufactured by Nippon Denshoku Industries Co., Ltd. It was measured. The viscosity of the paint was measured using a B-type viscometer at a paint temperature of 25 ° C. Moreover, the surface resistance of the translucent conductive film was measured using a surface resistance meter Loresta AP (MCP-T400) manufactured by Mitsubishi Chemical Corporation. Furthermore, the transmittance (visible light) and haze value of the translucent conductive film were measured using a haze meter HR-200 manufactured by Murakami Color Research Laboratory. The film color of the light-transmitting conductive film is measured by first placing only the substrate on which the light-transmitting conductive film is not formed on a calibration white plate (L * = 95.5). Then, a substrate having a light-transmitting conductive film formed thereon was placed on the calibration white plate.

[Example 1]
As the ITO needle-shaped powder A, SCP-X700B manufactured by Sumitomo Metal Mining Co., Ltd. was used. This ITO needle-like powder A has an average major axis of about 50 μm, a ratio of major axis to minor axis (aspect ratio) of about 14, a tin content of 2.5% by weight, a specific surface area of 9.0 m ² / g, and a lattice constant. Is 1.0191 nm, powder color (light source: D65, viewing angle: 10 °) in the L ^* a ^* b ^* color system is L ^* = 83.4, a ^* = − 4.2, b ^* = 6. 1. Further, the dust resistance value measured in a pellet form at a pressure of 980 Pa (100 kgf / cm ² ) is 0.06 Ω · cm.

Moreover, as ITO needle-like powder B, Sumitomo Metal Mining Co., Ltd. SCP-X1200 was used. The ITO needle-like powder B has an average major axis of about 50 μm, a ratio of major axis to minor axis (aspect ratio) of about 14, a tin content of 2.5% by weight, a specific surface area of 1.0 m ² / g, and a lattice constant. Is 1.0221 nm, the powder color (light source: D65, viewing angle: 10 °) in the L ^* a ^* b ^* color system is L ^* = 85.8, a ^* = − 5.9, b ^* = 17. 7. Further, the dust resistance value measured in a pellet form at a pressure of 980 Pa (100 kgf / cm ² ) is 0.02 Ω · cm.

  Next, the ITO needle-shaped powders A and B are mixed at a ratio of A: B = 50: 50 (weight ratio), a solvent (ethylene glycol monobutyl ether acetate) in which a binder (urethane-modified polyester resin) is dissolved, and curing A light-transmitting conductive paint according to Example 1 (ITO needle powder A: 14%, ITO needle powder B: 14%, urethane-modified polyester resin: 15.1%, dispersed in an agent (isocyanate) and a dispersant. Ethylene glycol monobutyl ether acetate: 55.6%, curing agent: 1.0%, dispersant: 0.3%). The viscosity of this paint was 5000 mPa · s.

  The translucent conductive paint according to Example 1 was screen-printed on a PET film (trade name: Lumirror, thickness: 100 μm) manufactured by Toray Industries, Inc. as a substrate while changing the mesh size and the sweep speed of the squeegee. Then, by heating at 120 ° C. for 20 minutes, a plurality of translucent conductive films having different film thicknesses were obtained.

FIG. 1 shows the relationship between the transmittance and the surface resistance value of the plurality of translucent conductive films according to Example 1. The haze value of these translucent conductive films was in the range of 60 to 95%. Further, the film color (light source: D65, viewing angle: 10 °) in the L ^* a ^* b ^* color system of these light-transmitting conductive films is L ^* = 92 in the range of 60 to 85% transmittance. -97, a ^* =-5 to -2.5, and b ^* = 8.5 to 15.

In addition, the transmittance | permeability (visible light) and haze value of a translucent conductive film are values only of a translucent conductive film, and are calculated | required by the following formula, respectively:
Transmissivity of translucent conductive film (%) = [(transmittance measured for each substrate with translucent conductive film) / (transmittance of substrate)] × 100
Haze value of translucent conductive film (%) = (Haze value measured for each substrate with translucent conductive film) − (Haze value of substrate)

[Example 2]
A plurality of translucent conductive films having different film thicknesses were obtained in the same manner as in Example 1 except that the weight ratio of the ITO needle-like powders A and B was A: B = 30: 70. FIG. 2 shows the relationship between the transmittance and the surface resistance value of the plurality of translucent conductive films according to Example 2. The haze value of these translucent conductive films was in the range of 60 to 95%. Further, the film color (light source: D65, viewing angle: 10 °) in the L ^* a ^* b ^* color system of these light-transmitting conductive films is L ^* = 92 in the range of 60 to 85% transmittance. ˜97, a ^* = − 6 to −2.7, b ^* = 9 to 18.

[Comparative Example 1]
A plurality of translucent conductive films having different film thicknesses were obtained in the same manner as in Example 1 except that only the ITO needle powder A was used. About the some translucent conductive film by these comparative examples 1, the relationship of the transmittance | permeability and a surface resistance value is shown to FIGS. The haze value of these translucent conductive films was in the range of 60 to 95%. Further, the film color (light source: D65, viewing angle: 10 °) in the L ^* a ^* b ^* color system of these light-transmitting conductive films is L ^* = 92 in the range of 60 to 85% transmittance. -97, a ^* =-4.5 to -2, b ^* = 8-13.

[Comparative Example 2]
Except having used only the said ITO needle-like powder B, it carried out similarly to Example 1, and obtained the some translucent electrically conductive film from which film thickness differs. About the some translucent conductive film by these comparative examples 2, the relationship between the transmittance | permeability and a surface resistance value is shown to FIGS. The haze value of these translucent conductive films was in the range of 60 to 95%. Further, the film color (light source: D65, viewing angle: 10 °) in the L ^* a ^* b ^* color system of these light-transmitting conductive films is L ^* = 92 in the range of 60 to 85% transmittance. -97, a ^* =-7 to -3, b ^* = 9.5 to 22.

[Comparative Example 3]
A plurality of translucent conductive films having different film thicknesses were obtained in the same manner as in Example 1 except that the weight ratio of the ITO needle-like powders A and B was A: B = 70: 30. FIG. 3 shows the relationship between the transmittance and the surface resistance value of the plurality of translucent conductive films according to Comparative Example 3. The haze value of these translucent conductive films was in the range of 60 to 95%. Further, the film color (light source: D65, viewing angle: 10 °) in the L ^* a ^* b ^* color system of the plurality of light-transmitting conductive films is L ^* = 92 in the transmittance range of 60 to 85%. -97, a ^* =-4.5 to -2, b ^* = 8-14.

  When the above-described Examples 1 and 2 and Comparative Examples 1 and 2 are compared, by mixing the ITO needle-shaped powders A and B, coloring of the translucent conductive film can be suppressed, and from FIG. 1 and FIG. Thus, a low-resistance translucent conductive film can be obtained in the range of low transmittance to high transmittance.

  Further, as can be seen from FIG. 3, the conductive property of the light-transmitting conductive film of Comparative Example 3 is the same as that of Comparative Example 1, so that the weight ratio of the conductive oxide needle-shaped powders A and B is A: B. It can be seen that outside the range of 35:65 to 20:80, the conductive properties are not improved.

It is a graph which shows the relationship between the transmittance | permeability in the some translucent conductive film obtained in Example 1, and Comparative Examples 1 and 2, and a surface resistance value. It is a graph which shows the relationship between the transmittance | permeability in the some translucent conductive film obtained in Example 2, and Comparative Examples 1 and 2, and a surface resistance value. It is a graph which shows the relationship between the transmittance | permeability in the some translucent electrically conductive film obtained by the comparative examples 1 and 3, and a surface resistance value.

Claims (7)

In the translucent conductive paint in which conductive oxide needle-shaped powder made of indium oxide doped with metal oxide is dispersed in a solvent containing a binder, the conductive oxide needle-shaped powder has a specific surface area of 4 to 20 m. ² / g and the powder color in the L ^* a ^* b ^* color system (light source: D65, viewing angle: 10 °) is L ^* = 82 to 91, a ^* = − 8 to 2, b ^* = 0 to The conductive oxide needle-like powder A is 10 and the specific surface area is less than 4 m ² / g and the powder color (light source: D65, viewing angle: 10 °) in the L ^* a ^* b ^* color system is L ^*. Conductive oxide needle-like powder A and conductive oxide needle-like powder B, which are = 82 to 91, a ^* = − 8 to 2, and b ^* = 15 to 20. The weight ratio of A: B is 35:65 to 20:80.   The translucent conductive paint according to claim 1, wherein the conductive oxide needle-like powder A has a lattice constant of 1.0118 to 1.0120 nm.   The translucent conductive paint according to claim 1 or 2, wherein the conductive oxide needle-like powder B has a lattice constant of 1.021 to 1.0123 nm.   The translucent conductive paint according to any one of claims 1 to 3, wherein both the aspect ratios of the conductive oxide needle-shaped powder A and the conductive oxide needle-shaped powder B are 5 or more.   The translucent conductive paint according to claim 1, wherein the metal oxide is at least one selected from tin oxide, zirconium oxide, zinc oxide, tungsten oxide, and titanium oxide.   The weight ratio of the conductive oxide needle-shaped powder and the binder is conductive oxide needle-shaped powder: binder = 40: 60 to 90:10, according to any one of claims 1 to 5. Translucent conductive paint.   A translucent conductive film formed using the translucent conductive paint according to claim 1, wherein the translucent conductive film has a surface resistance of 1000Ω / □ or less at a transmittance of 72%. And a translucent conductive film characterized by having a transmittance of 81% and 10000 Ω / □ or less.

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