JP3129140B2 - Composition and method for forming conductive film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for forming a conductive film which can be used in fields such as electrophotographic recording, transparent electrodes, antistatic, heat ray reflection, and surface heating elements. The composition of the present invention can easily form a transparent electrode circuit by coating or printing on an insulator.

[0002]

2. Description of the Related Art A transparent film of an oxide semiconductor generally shows a high transmittance to visible light, and has a low resistance and a high film strength. It is widely used as a reflection film, an antistatic film in electrophotographic recording, and as a surface heating element. A typical example of such an oxide semiconductor is indium oxide containing tin (hereinafter, referred to as ITO).

[0003] For convenience, the following description will focus mainly on the field of transparent electrodes, which have the strictest required performance. As a conventional method for forming a transparent conductive film, a metal or an inorganic substance (particularly, ITO) is vacuum-deposited, sputtered,
A method of applying by a dry process such as ion plating, a method of applying an organometallic compound solution on a substrate, baking after drying (sol-gel method), dispersing ITO powder treated with a dispersant in a resin liquid, There is a method (powder method) of forming a coating by coating or printing into a coating or ink and forming the coating.

[0004] Dry processes such as evaporation and sputtering are the most widely used film forming methods in the past. However, there is a limit to the enlargement of the electrode area. Due to low efficiency, IT
The effective utilization efficiency of O is very low at 40 to 50%. When a circuit is drawn by the etching method, the I
There are also disadvantages that most of the TO is removed and that the equipment cost is high.

On the other hand, in the sol-gel method in which an organometallic compound solution is applied onto a substrate, dried and then fired, the firing temperature is high, so that the material of the substrate is limited and the sol-gel method is formed by one application. Since the film thickness is very thin, it is difficult to obtain appropriate film characteristics by one coat and one bake, and the application and baking are repeated many times, so that the operation becomes complicated.

After the ITO powder is surface-treated with a wetting agent or a pigment dispersant, it is dispersed in a resin solution, or the ITO powder is dispersed in a solvent containing a dispersant and a resin. Alternatively, in the case of the powder method in which a transparent conductive film is formed using ink, a circuit can be directly drawn by a method such as screen printing, so that there is no waste of material. In addition, since drying can be performed at a relatively low temperature required for removing the solvent or thermally curing the resin, the present invention can be applied to a substrate having low heat resistance such as a resin.

[0007]

However, in the powder method, a dispersing agent and a resin for binding (eg, a thermoplastic, thermosetting, or ultraviolet curable resin) for dispersing and binding the ITO powder are used. High molecular substances are required. However, since such a polymer material generally acts as an insulator, if the polymer material is densely adsorbed on the surface of the ITO powder, contact between the ITO powders in the formed coating film becomes poor, and the An insulating layer is formed on the surface, and the conductivity is reduced.

[0008] In this regard, after coating and drying (removal of the solvent), rolling treatment with a steel roll is performed to suppress the generation of voids and smooth the surface, thereby improving the electrical and optical characteristics of the ITO transparent conductive film. (Japanese Unexamined Patent Publication Nos. 4-237908 and 4-237909).
However, even if such a rolling treatment is performed, sufficient electric characteristics and optical characteristics have not yet been obtained.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, apply to a resin substrate having low heat resistance, and form a conductive film forming composition and a conductive film capable of forming a conductive film having low resistance and high light transmittance. It is an object of the present invention to provide a forming method.

[0010]

According to the present invention, the above object is achieved by preliminarily treating a surface of an ITO powder with a fluorine-containing inert organic liquid and impregnating the surface of the powder with the liquid.

Here, the present invention relates to a composition for forming a conductive film in which ITO powder is dispersed in a resin solution,
A composition for forming a conductive film, wherein the O powder has been surface-treated in advance with a fluorine-containing inert organic liquid in an amount of 0.1 to 5% by weight based on the powder.

From another aspect, the present invention provides a method for printing or coating the above-mentioned composition for forming a conductive film on a substrate, and then forming the conductive film on the substrate by drying, thermosetting, and / or ultraviolet irradiation. And a conductive film forming method. In this method, the film on the substrate may be subjected to heat and pressure treatment after drying and before heat curing or irradiation with ultraviolet light, during heat curing or irradiation with ultraviolet light, or after forming a conductive film on the substrate.

Hereinafter, the present invention will be described in detail. The composition for forming a conductive film according to the present invention is a paint or ink-like composition in which ITO powder (tin-containing indium oxide powder) is dispersed in a resin solution, and which can be applied or printed.

The ITO powder is based on the total amount of (In + Sn).
Sn content is 1 to 15 mol%, average primary particle size is 0.2 μm
Hereinafter, particularly, ultrafine powder having a particle size of 0.1 μm or less is preferable. If the Sn content is outside the above range, the conductivity will be reduced, and if the average primary particle diameter exceeds 0.2 μm, the transparency of the conductive film will be reduced.

The proportion of the ITO powder in the composition of the present invention is as follows:
It is preferably in the range of 15 to 80% by weight based on the nonvolatile content (total weight of the composition excluding the solvent in the resin solution). A more preferable ratio of the ITO powder is 20 to
It is 80% by weight, particularly preferably 40-75% by weight. If the amount is less than 15% by weight, the conductivity of the obtained film is low, and if it exceeds 80% by weight, the strength of the film tends to decrease.

According to the present invention, the surface of the ITO powder is preliminarily treated with a fluorine-containing inert organic liquid before being dispersed in the resin liquid, and the surface is impregnated with the fluorine-containing inert organic liquid. As a result, the ITO powder is densely filled in the conductive film, and not only the electrical characteristics but also the optical characteristics (transparency) are improved. The fluorine-containing inert organic liquid is removed by evaporation during drying or curing after applying or printing the composition of the present invention.

As the fluorine-containing inert organic liquid, one or two kinds selected from the group consisting of chlorofluorocarbons, aromatic fluorides, ether compounds having a perfluoroalkyl group, amine compounds, and alcohol compounds The above compounds can be used. Such a fluorine-containing organic liquid can be produced by a conventional method such as a reaction between chlorocarbon and hydrofluoric acid, telomerization of ethylene and chlorofluorocarbon, and an electrolytic fluorination method.

"Inert" means that the fluorine-containing organic liquid contains the resin liquid (ie, resin component and solvent) and I
It means that it has no substantial reactivity with any of the TO powders. For example, an organic fluorine compound containing an acid group such as a carboxylic acid group or a sulfonic acid group generally acts as a strong acid and exhibits high reactivity, and thus cannot be said to be inert.
Such an active fluorine-containing organic liquid may react with the resin component, the solvent, or the ITO powder, and may reduce the optical and / or electrical properties of the conductive film formed thereby. In some cases, it is toxic.

It is preferable to use a fluorine-containing inert organic liquid having a boiling point (boiling point at 1 atm) of 250 ° C. or less, that is, in the range of room temperature to 250 ° C. If the boiling point is lower than room temperature, it will volatilize at room temperature, making it difficult to sufficiently impregnate the ITO powder. On the other hand, a high-boiling fluorine-containing inert organic liquid having a boiling point higher than 250 ° C. has too low volatility and remains in the coating film even after the coating film is dried, and the electrical and / or optical properties of the formed conductive film are high. Lower. This boiling point is more preferably at most 200 ° C.

As the fluorine-containing inert organic liquid to be used, it is advantageous to select one having an appropriate boiling point depending on the properties of the resin liquid for forming the coating film. For example, when the resin liquid is cured without requiring heating such as drying at room temperature or ultraviolet curing, it is preferable to use a fluorine-containing inert organic liquid having a relatively low boiling point and high volatility. On the other hand, when the resin liquid is cured by heating such as heat curing or heat drying, a fluorine-containing inert organic liquid having a relatively high boiling point is used so that the fluorine-containing inert organic liquid also evaporates during this heating. Is preferred.

When a high boiling point fluorine-containing inert organic liquid is used in a curing method that does not require heating, the evaporation of this liquid is slow, the surface of the ITO particles is covered with an insulating layer, and the electrical characteristics are reduced. Becomes On the other hand, in the case of curing by heating, if the fluorine-containing inert organic liquid impregnated in the ITO powder has a low boiling point, the evaporation of this liquid occurs rapidly, and fine pores are generated on the coating film surface, and the optical characteristics are reduced. Leads to a decline.

Specific examples of the fluorine-containing inert organic liquid that can be used in the present invention include Freon 113, hexafluorobenzene, trifluoroethanol, perfluorotributylamine, perfluorotetrahydrofuran, etc., but these are only representative examples. However, other fluorine-containing organic liquids can also be used if they are inert.

The surface treatment of the ITO powder is carried out using a fluorine-containing inert organic liquid in an amount of 0.1 to 5% by weight based on the ITO powder. The surface treatment can be performed by any method capable of uniformly contacting the ITO powder so that the ITO powder is sufficiently impregnated with the fluorine-containing inert organic liquid. For example, the ITO powder is stirred and held in a fluidized state in a closed container, a predetermined amount of a fluorine-containing inert organic liquid is dropped or sprayed into the container, and the stirring is continued to further impregnate the ITO powder with the liquid. Can be done. Although the treatment temperature is not particularly limited, room temperature is usually sufficient. The treatment (contact) time is generally preferably in the range of 15 seconds to 30 minutes, particularly preferably in the range of 30 seconds to 10 minutes.

When the amount of the fluorine-containing inert organic liquid used for the surface treatment exceeds 5% by weight of the ITO powder, the ITO powder impregnated with the liquid no longer exists as a solid, or the ITO powder is dispersed in the resin liquid. Aggregation occurs when this is performed, resulting in non-uniformity of the conductive film, which causes a decrease in light transmittance. On the other hand, if this amount is less than 0.1% by weight, remarkable superiority in the properties of the conductive film cannot be obtained as compared with the case where no surface treatment is performed.

The composition for forming a transparent conductive film of the present invention is obtained by coating the ITO powder surface-treated as described above with a resin solution (a solution obtained by dissolving the resin in a solvent, or, in some cases, when the resin itself is liquid). (Resin itself). The resin to be present in the resin liquid may be any of a thermoplastic resin, a thermosetting resin, and an ultraviolet-curable resin, and one or more of them may be used. The resin used has only to have solubility in an appropriate solvent and have sufficient transparency, and the type, molecular weight, acid value and the like are not particularly limited. In the case of a heat or ultraviolet curable resin, any of monomers, oligomers and polymers can be used. Illustrative examples of resins suitable for use in the present invention include thermoplastic resins such as polyvinyl chloride, polyvinyl acetate, polyester, and thermoplastic acrylic resins, and thermosetting resins such as epoxy resins and thermosetting resins. Acrylic resins and the like, and ultraviolet curable resins include epoxy acrylate and urethane acrylate.

The solvent for dissolving the resin is not particularly limited as long as it dissolves the resin to be used and substantially completely evaporates after drying or heating and does not hinder the transparency of the coating film. Both a polar solvent and a non-polar solvent can be used, and a mixed solvent obtained by mixing two or more solvents can also be used. The amount of the solvent used is not particularly limited as long as a composition having a viscosity suitable for the coating or printing method to be used is obtained.

In the present invention, it is preferable to use a mixed solvent of at least one polar solvent and at least one non-polar solvent. Polar solvents have a strong affinity for ITO powder, and the polymer material (resin) that forms the insulating layer is ITO.
It has a strong effect of preventing it from being adsorbed on the surface of the powder. On the other hand, the non-polar solvent has a weak affinity for the ITO powder, so that this effect is weak. By coexisting the two, the amount of the polymer substance adsorbed on the surface of the ITO powder is controlled, and an appropriate amount of the polymer substance required for bonding is adsorbed. Is improved.

Examples of the polar solvent include solvents having a hydroxyl group or a ketone group such as methanol, ethanol, butanol, diacetone alcohol, diethylene glycol, butyl carbitol, isophorone and cyclohexanone. Examples of the non-polar solvent include hydrocarbons such as aromatic hydrocarbons such as xylene and toluene, alicyclic hydrocarbons such as cyclohexane, and aliphatic hydrocarbons such as hexane and octane. The ratio between the polar solvent and the non-polar solvent in the mixed solvent is not particularly limited, but the weight ratio of the polar / non-polar solvent is 5/95 to 95/5, particularly 30/50 to 50/30.
Is preferably within the range. The polar solvent and the non-polar solvent to be used need to be a combination having good compatibility between the solvents and being homogeneously mixed.

The dispersion of the ITO powder in the resin solution can be performed by a conventional method using a paint shaker, ball mill, sentry mill,
It can be performed using a powerful mixing device such as a sand grind mill, whereby the composition for forming a conductive film of the present invention can be obtained. The amount of the ITO powder in the obtained composition is preferably in the range of 15 to 80% by weight based on the nonvolatile content as described above.

The composition for forming a conductive film of the present invention comprises a resin, I
In addition to TO powder, organic solvent, and fluorine-containing inert organic liquid, if necessary, a crosslinking agent, a curing catalyst, a photopolymerization initiator,
Additives such as wetting agents, dispersants, antioxidants, and leveling agents can be further included.

This composition is applied or screen-printed on a suitable substrate as a paint or ink, and if necessary, the film is cured by heating, irradiating with ultraviolet light, or both, to form a transparent conductive film. . The curing of the film
Occurs by drying (natural or thermal drying), heat curing, or UV curing depending on the resin type. The substrate material is not particularly limited, and a transparent insulating material such as glass and plastic is preferable, but an opaque insulating material such as ceramic or a conductive material such as metal may be used depending on the application.

The coating method is not particularly limited.
Examples include a dipping method, a spin coating method, a spray method, a bar coating method, and a roll coating method. By printing on an insulating substrate, the conductive film circuit can be drawn directly on the substrate, and the circuit formation using a photoresist is not required. Therefore, the operation is greatly simplified, and waste of material can be avoided. Curing conditions vary depending on the resin and solvent used, but those skilled in the art can easily set the curing conditions.

In the present invention, the fluorine-containing inert organic liquid exerts many effects. First, since the fluorine-containing inert organic liquid has a low surface tension, it easily penetrates into the gaps between the ITO powders and uniformly covers the surface. In addition, since the fluorine-containing inert organic liquid has a very small interaction force between molecules, the impregnated ITO powder can suppress the repulsion between the powders after being applied, and can be densely filled in the coating film.

Further, since a fluorine-containing inert organic liquid is hardly dissolved in a general organic solvent, even if the impregnated ITO powder is dispersed in a resin solution, it is difficult to dissolve in a resin or an organic solvent. , And is held in a state of being adsorbed on the surface of the ITO powder, and continues to exert the above-described repulsion suppressing action.

Further, since the fluorine-containing inert organic liquid has extremely low reactivity, it is difficult to use a resin, a solvent,
It does not react with the TO powder itself and does not adversely affect the electrical and optical properties of the coating. Moreover, the fluorine-containing inert organic liquid suppresses repulsion between ITO powders,
It does not affect the dispersibility of the ITO powder.

On the other hand, by selecting a fluorine-containing inert organic liquid having an appropriate boiling point, the fluorine-containing inert organic liquid can be substantially completely evaporated during drying or heating after coating to be removed from the coating film. If the fluorine-containing inert organic liquid remains in the coating after application, the electrical and optical properties of the coating deteriorate.

As described above, while the fluorine-containing inert organic liquid is in a solution state in which the repulsion of the ITO powders is desired to be suppressed, the fluorine-containing inert organic liquid does not adversely affect the coating film and continues to exert the repulsion suppressing effect effectively. Since it is removed in the process, the characteristics of the finally formed conductive film are well maintained. As a result, a conductive film that is densely filled with the ITO powder and has improved electrical characteristics (particularly, conductivity) and optical characteristics (particularly, transparency) is formed. This effect is peculiar to the fluorine-containing inert organic liquid, and a hydrocarbon-based liquid cannot provide all of this low surface tension, low reactivity, and high volatility.

When it is desired to obtain a conductive film having a lower resistance and a higher light transmittance, the conductive film on the substrate can be heated and pressed.
This heat-pressing process is performed for the entire substrate while the film has deformability. Therefore, although it depends on the type of resin, after drying and before thermosetting or ultraviolet irradiation, during thermosetting or ultraviolet irradiation, or after forming a conductive film on a substrate
(That is, after heat curing or irradiation with ultraviolet rays). For example, in the case of a thermosetting resin, hot pressing and thermosetting can be achieved simultaneously by hot pressing after drying.

The method of hot pressing is not particularly limited, and examples thereof include rolling with a hot steel roll and press forming with a hot press. The conditions of the heat and pressure are not particularly limited because they vary depending on the heat resistance and pressure resistance of the substrate material, required coating film characteristics, and the like. For example, in the case of rolling by a hot roll,
Temperature 80 to 150 ° C., linear pressure 300 to 600 kg / cm ² about roles, temperature 100 to 180 ° C. in the case of hot pressing, the pressure
About 20-50 kg / cm ² is desirable.

Due to the heat and pressure, the ITO particles in the film are mechanically and more densely packed, and the ITO particles approach each other. As a result, the electrical characteristics are improved, and the optical characteristics are also increased due to the smoothing of the coating film surface. Thus, in general, the higher the pressure, the better the film properties.

Since the composition for forming a conductive film according to the present invention can form a transparent conductive film on a substrate by coating, screen printing or the like, the composition can be applied to a resin substrate having relatively low heat resistance, and the area of the conductive film can be increased. And continuous mass production can be easily realized. The transparent conductive film formed by using the composition of the present invention has a surface resistance on the order of 10 ² to 10 ³ Ω / □ and a light transmittance by adjusting the film thickness and the ITO content in the composition. In the range of 80 to 90%, it can be adjusted according to the application.

[0042]

The present invention will be specifically described below with reference to examples. The ITO powders used in the examples were all (In + Sn)
5 mol% of Sn to the average primary particle diameter is 0.05μ
m.

[0043]

Example 1 95.0 g of ITO powder was put into a juicer mixer, and while maintaining a fluid state with vigorous stirring, an amine type compound having a perfluoroalkyl group was used.
5.0 g of EF-L174 (perfluorotributylamine) manufactured by Tochem Products was added dropwise. After dropping, 3 more
By continuing stirring for minutes, an ITO powder impregnated with a fluorine-containing inert organic liquid was obtained.

On the other hand, a flask equipped with a reflux tube, a thermometer, a dropping funnel and a stirrer was charged with 60 g of xylene,
After the temperature was raised to 85 ° C, 20 g of styrene and methyl acrylate 2
A mixture consisting of 0.0 g, 1.2 g of mono (2-methacryloyloxyethylene) acid phosphate and 1.0 g of azobisisobutyronitrile was added over 5 hours, and the mixture was reacted for 12 hours. A resin solution having a weight average molecular weight of the resin of 220,000 and an acid value of 5.5 was obtained.

50.0 g of this resin liquid, ITO powder impregnated with the amine compound having a perfluoroalkyl group
80.0 g, 120.0 g of a mixed solvent having a butanol / xylene weight ratio of 5: 5, and 250 g of glass beads were placed in a 500 cc container, and kneaded for 5 hours while checking the dispersion state with a particle shaker using a paint shaker.

After kneading, the glass beads were removed, and ITO was removed.
A viscous liquid conductive film forming composition in which particles were uniformly dispersed in a resin liquid was obtained. Thereafter, the liquid composition was applied on a PET film using an applicator, and dried at 100 ° C. for 1 hour to form a transparent conductive film having a thickness of 3 μm on the PET film.

[0047]

Example 2 As a fluorine-containing inert organic liquid for surface treatment, an ether type compound having a perfluoroalkyl group, EF-L1023.0 manufactured by Tochem Products Co., Ltd.
g, and the amount of ITO powder was changed to 97.0 g, and the same operation as in Example 1 was performed to obtain an ITO powder impregnated with a fluorine-containing inert organic liquid.

Next, 124 ml of xylene was added to Daiichi Mining
1.2 g of a surfactant SAS-13 manufactured by Co., Ltd. was added and dissolved, and 60 g of the ITO powder impregnated with the above-mentioned fluorine-containing inert organic liquid was added thereto.
The mixture was mixed and stirred at 0 rpm for about 30 minutes to prepare a dispersion in which the ITO powder was dispersed.

Separately from this, Mitsubishi Kasei was replaced with 120 cc of hexane.
0.3 g of Stabilizer 2000E manufactured by Kaneka Corporation was dissolved, and 21.8 g of Kaneka M1008 (vinyl chloride-5 wt% vinyl acetate copolymer having an average molecular weight of 800) was dissolved therein to prepare a resin solution.

The ITO powder dispersion and the resin solution are kneaded with a homogenizer at 5000 rpm for about 4 hours to obtain a viscous liquid conductive film forming composition in which ITO particles are uniformly dispersed in the resin solution. Was. This liquid composition was applied on a PET film using an applicator and dried at 80 ° C. for 3 hours.
A transparent conductive film having a thickness of 3 μm was formed on the PET film.

[0051]

Example 3 As a fluorine-containing inert organic liquid for surface treatment, 0.9 g of trifluoroethanol manufactured by Tochem Products Co., Ltd., which is an alcohol compound having a perfluoroalkyl group, was used, and the amount of ITO powder was 99.1 g. The procedure was the same as that of Example 1 except that the ITO powder was impregnated with a fluorine-containing inert organic liquid.

On the other hand, as a thermosetting resin, Tokyo Paint
A resin solution was prepared by dissolving 30.0 g of Epoxy Resin Co., Ltd. in 80.0 g of methanol, and 70 g of the surface-treated ITO powder was added to the resin solution. A viscous liquid conductive film forming composition in which the powder was uniformly dispersed in the resin liquid was obtained. The liquid composition was applied on a glass plate using an applicator, and dried at 100 ° C. for 2 hours to form a 3 μm-thick transparent conductive film on the glass plate.

[0053]

Example 4 As a fluorine-containing inert organic liquid for surface treatment, a chlorofluorocarbon-based 1,1,2-trichloro-2,2,2
Using 2.0 g of 1-trifluoroethane (Freon 113),
An ITO powder impregnated with a fluorine-containing inert organic liquid was obtained in the same manner as in Example 1 except that the amount of the TO powder was changed to 98.0 g.

On the other hand, an epoxy acrylate UV curable resin [Unidick V-5500 manufactured by Dainippon Ink and Chemicals, Inc.] 3
0.0 g, the above-mentioned surface-treated ITO powder 70.0 g, and acetone 100 g were kneaded in the same manner as in Example 1, and the ITO powder was uniformly dispersed in a resin solution to form a viscous liquid conductive film forming composition. I got The liquid composition is applied on a PET film using an applicator, and irradiated with ultraviolet rays for 30 seconds using a 300 W high-pressure mercury lamp [UMA-3012-N4 type manufactured by Ushio Inc.] to apply the liquid composition on the PET film. A transparent conductive film having a thickness of 2 μm was formed.

[0055]

Example 5 As a fluorine-containing inert organic liquid for surface treatment, an aromatic fluorinated substance, hexafluorobenzene 5.0
g and the amount of ITO powder was changed to 95.0 g, and the same operation as in Example 4 was performed to form a viscous liquid conductive film in which the ITO powder was uniformly dispersed in the ultraviolet curable resin liquid. A composition for use was obtained. Thereafter, a transparent conductive film having a thickness of 2 μm was formed on the PET film by the same operation as in Example 4.

[0056]

Comparative Example 1 The same operation as in Example 1 was performed except that the ITO powder was used as it was.

[0057]

Comparative Example 2 The same operation as in Example 2 was performed except that the ITO powder was used as it was.

[0058]

Example 6 Two 50 mm diameter steel rolls having hard chrome plating on the roll surface were processed at a processing speed of 10 cm /
The rotation speed was set so as to be seconds, and the PET film having the transparent conductive film obtained in Example 1 was set between the steel rolls. This PET film was roll-rolled with a sintered body under the conditions of a steel roll temperature of 60 ° C. and a linear pressure of 400 kgf / cm, and was subjected to hot pressing.

[0059]

Embodiment 7 PET having the transparent conductive film obtained in Embodiment 2
The film, after placing the polyvinyl chloride resin plate having a thickness of 3 mm, sandwiched surface two mirror plates polished buffed, temperature 0.99 ° C., thermal pressure treatment by hot pressing at a pressure 40 kgf / cm ² did.

[0060]

Comparative Example 3 PET having the transparent conductive film obtained in Comparative Example 1
The film was hot-pressed by rolling in the same manner as in Example 6.

With respect to the transparent conductive films obtained in the above Examples and Comparative Examples, the total light transmittance was measured by U
Haze is measured by Suga Test Machine Co., Ltd. with a BEST55 spectrophotometer.
The surface resistance was measured with an SM color computer, and the surface resistance was measured with a Loresta APMCP-T400 surface resistance meter manufactured by Mitsubishi Yuka Corporation. Table 1 shows the test results.

[0062]

[Table 1]

[0063]

The composition for forming a transparent conductive film of the present invention used in the examples had been surface-treated with a fluorine-containing inert organic liquid before dispersing the ITO powder in the resin solution. As a result, a transparent conductive film having extremely low resistance and excellent conductivity can be formed as compared with the comparative example using untreated ITO powder. In addition, the transparent conductive film has a greatly reduced haze value, a high total light transmittance, and improved optical characteristics as well as electrical characteristics.

In addition, I by a fluorine-containing inert organic liquid
Since the dispersibility of the ITO powder is improved by the surface treatment of the TO powder, it is possible to disperse the ITO powder in the resin liquid without using a dispersant as shown in Examples 1, 3 to 5. Becomes Further, when the formed transparent conductive film is subjected to a heat and pressure treatment, the electric characteristics and the optical characteristics can be further improved.

Continued on the front page (72) Inventor Masahiro Hagiwara 1-297 Kitabukuro-cho, Omiya-shi, Saitama Prefecture Mitsui Materials Co., Ltd. Central Research Laboratory (72) Inventor Masahiro Sekiguchi 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsui Materials Co., Ltd. (56) References JP-A-63-211514 (JP, A) JP-A-6-340829 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 13 / 00 H01B 1/22 H01B 5/14

Claims (5)

(57) [Claims] 1. A composition for forming a conductive film, comprising a tin-containing indium oxide powder dispersed in a resin liquid, wherein the indium oxide powder has a fluorine content of 0.1 to 5% by weight based on the powder. A composition for forming a conductive film, which has been surface-treated in advance with an inert organic liquid. 2. The composition according to claim 1, wherein the surface-treated indium oxide powder is contained in an amount of 15 to 80% by weight of a nonvolatile content of the composition.
The composition for forming a conductive film according to claim 1. 3. The conductive film forming composition according to claim 1, wherein the resin solution is a solution obtained by dissolving a resin in a mixed solvent of a polar solvent and a non-polar solvent. 4. The conductive film-forming composition according to claim 1, which is printed or coated on a substrate, and then dried, thermally cured, and / or irradiated with ultraviolet light to form a conductive film on the substrate. Forming a conductive film. 5. The method according to claim 4, wherein after drying and before heat curing or UV irradiation, during heat curing or UV irradiation, or after forming a conductive film on the substrate,
A method for forming a conductive film, wherein a film on a substrate is subjected to a thermal pressure treatment.