JPH067444B2 - Composition for forming transparent conductive film containing organoindium sol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition for forming a transparent conductive film containing a stable organoindium sol.

The transparent conductive film is used as a transparent electrode such as an electrode of a liquid crystal display element, an electroluminescence display element, a photocell, a photosensitive element such as an image pickup tube, or a surface heating element electrode.

As such a transparent electrode material, many materials such as indium oxide-tin oxide or tin oxide-antimony oxide are generally known, and a transparent conductive film is obtained by coating and baking on a glass or ceramic substrate, It is used industrially. Among them, an indium oxide-tin oxide based oxide film is particularly widely used as an ITO (Indium Tin Oxide) film.

The ITO film is formed by vacuum deposition, sputtering, CVD, etc., but the processing technology is difficult, the processing area is limited, and the physical properties such as the hardness of the film are not satisfactory. IT that can be applied by the coating method, which is advantageous as
A composition for O film has been desired.

InCl ₃ , In (NO ₃ ) ₃ as ITO film composition that can be applied
Inorganic salt such as indium soap, indium chelate,
Although a composition using an organic compound such as indium alkoxide has been proposed, it has a problem in film-forming properties, and it is difficult to form a uniform film, or the formed film lacks transparency and becomes cloudy. However, the film strength and adhesiveness are not sufficient.
Furthermore, there was a problem of evaporation of the ITO film material during firing, which was not satisfactory. A method has been proposed in which an inorganic indium sol is used as a composition for forming an ITO film, which has film-forming properties and does not evaporate during firing (JP-A-59-219810).

The sol composition containing indium oxide sol as the main component lacks stability, as is clear from the behavior of the isomorphic sol composition of aluminum of the periodic table, and easily separates due to aggregation and separation, resulting in nonuniform coating and storage stability. However, it was not satisfactory because there was a defect that it was difficult to apply it to continuous work.

However, it is expected that a practically preferable ITO film-forming composition can be obtained when an indium sol having stable dispersibility can be obtained while maintaining the film forming property. Therefore, a sol composition having such characteristics is required. As a result of intensive investigations, they found that the chelated indium hydroxide sol had preferable physical properties, and developed an ITO film composition containing the sol to arrive at the present invention.

Thus, according to the present invention, a chelating agent selected from β-diketone and β-ketoester is added to a water-soluble lower alcohol solution of an indium compound represented by the general formula InX ₃ (X represents a halogen or a nitric acid group). A transparent conductive film-forming composition obtained by adding a tin compound at a Sn / In ratio of 0.5 to 30% by weight to a chelate indium hydroxide type organoindium sol obtained by treating Is provided.

The present invention further provides a transparent conductive film obtained by coating a substrate with a composition for forming a transparent conductive film obtained by adding a divalent tin chelate compound to a chelated indium hydroxide type organoindium sol and baking the composition. Is.

More specifically, when the coating film formed by the coating method is heated and dried at room temperature or at a low temperature that does not reach firing, a film substantially made of indium oxide containing tin in a predetermined ratio is formed. The indium sol used is preferably an indium sol having 2 or 3 hydroxyl groups. However, In (O
H) ₃ or its condensate, the indium sol represented by ₃ or its condensate, has poor storage stability even when a stabilizer such as an organic acid is used, and the indium sol yield is poor due to insolubilization during the sol production process. It was difficult to apply to.

When an indium sol is synthesized from an inorganic indium salt, it is treated with an anion exchange resin in the coexistence of a chelating agent, and an organosol containing monochelate indium dihydroxide as a main component is obtained. The primary film-forming property at the time of low temperature heating and drying was good, and it was excellent as a composition material for forming an ITO film.

In producing this organoindium sol, an inorganic indium compound represented by the general formula InX ₃ is used. Here, X is a halogen such as chlorine or bromine or a nitric acid group, and indium chloride and indium nitrate are preferably used. This compound is dissolved in a water-soluble lower alcohol to form a solution. Such alcohol is methanol,
Ethanol, propanol, isopropanol, butanol, secondary butanol, tertiary butanol, etc. alone or 2
A mixture of two or more species is used.

The water-soluble lower alcohol solution of the inorganic indium compound represented by the above general formula InX ₃ thus obtained was β-
A chelating agent selected from diketone, β-ketoester is added. Examples of β-diketone chelating agents include acetylacetone, acetylmethylethylketone, trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone, dibenzoylmethane, benzoylfluoroacetone, and the like, and examples of β-ketoester chelating agents include acetoacetate. Examples thereof include methyl acetate, ethyl acetoacetate, isopropyl acetoacetate and butyl acetoacetate. This chelating agent is added in the same molar amount or more with respect to the above-mentioned inorganic indium compound.

As described above, the chelating agent is added to the alcohol solution of the indium compound and then treated with the basic ion exchange resin. A moderately basic or weakly basic ion exchange resin having either a tertiary amine or a quaternary amine as an exchange group is preferably used.

When a chelating agent is added and treated with an ion exchange resin in this way, a chelation reaction and a hydroxide reaction occur to obtain an organoindium sol containing chelated indium hydroxide as a main component.

The obtained chelated indium hydroxide can be used by itself as a material for forming indium oxide for modifying surface properties.

However, as a composition for forming an ITO film, it is necessary to use a tin compound that can stably coexist with the above-mentioned organosol and forms a complex oxide with indium hydroxide during coating and drying. As tin compounds, metallic soap and general formula SnX ₄ · nH ₂
If an inorganic tin compound represented by O (X: halogen) is used, a good ITO film intended by the present invention cannot be formed.

Therefore, in the present invention, it is necessary to use the hydrolyzable divalent tin chelate compound which the present inventor previously researched and developed and applied for a patent. This tin chelate compound is a compound represented by the general formula SnY ₂ . Here, Y represents β-diketone, β-ketoester or N-alkyl group-substituted amino alcohol.

Therefore, in the present invention, the chelate indium hydroxide type organoindium sol is added to β-diketone, methyl acetoacetate, ethyl acetoacetate, acetoacetic acid represented by acetylacetone, hexafluoroacetylacetone, trifluoroacetylacetone, pentafluorobenzoylacetone, etc. Β-ketoesters represented by isopropyl and butyl acetoacetate, N, N-dimethylaminoalcohol, N-methylN-ethylaminoethanol,
When a divalent tin chelate compound having an N-alkyl group-substituted aminoalcohol typified by N, N-di (trifluoromethyl) aminoethanol as a chelate is used as a tin component, the film forming property is excellent and the transparency is excellent. A conductive film forming composition can be obtained.

Although the ratio of In-Sn can be determined by physical properties, the Sn / In ratio is preferably 0.5 to 30% by weight for forming a transparent conductive film, and formic acid, acetic acid, propionic acid, butyric acid as a stabilizer is optionally used when preparing a composition. , Isobutyric acid, glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, succinic acid, maleic acid, acetylacetone, benzoylacetone, benzoylmethane, methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, butyl acetoacetate, methyl lactate, It is also possible to use ethyl lactate, butyl lactate and the like. In addition, methyl cellulose, ethyl cellulose or the like can be added as a viscosity modifier depending on the case.

The ITO film can be formed on the substrate by a general method such as a spray method, a dipping method, a bar coating method, a roll coating method, a casting method and a spinner method. The substrate formed by coating is heated and dried at room temperature or a low temperature equal to or lower than the firing temperature to form an indium oxide-tin oxide primary coating. A transparent conductive ITO film can be obtained by firing this in air or in an inert gas atmosphere at 400 to 500 ° C. for 30 minutes to 1 hour.

The physical properties of the formed transparent conductive ITO film are as follows: the film hardness is 4H to 9H, the visible part transmittance is 90% or more, and the sheet resistance is 2K.
Ω / □, which is industrially useful.

[Reference Example-1] 100 parts by weight of indium chloride is dissolved in 820 parts by weight of 10% water-containing ethanol, and 50 parts by weight of acetylacetone and 30 parts by weight of lactic acid are added and uniformly dissolved. A column filled with 1800 parts by volume of a medium basic ion exchange resin (trade name: Amberlite IRA-68) was treated with a flow rate SV20H ^-1 to obtain a pale yellow transparent effluent. Residual chlorine in the effluent was not found by the silver nitrate method. A part of the effluent was collected and vacuum dried to obtain a white amorphous solid. In ₂ O ₃ analysis value of this solid is 55.7%.
Which is consistent with In (AA) (OH) ₂ (In ₂ O ₃ : 55.8%),
In addition, infrared analysis revealed that it was In (AA) (OH) ₂ .
This infrared spectrum is shown in the drawing. In the above formula, AA represents acetylacetone. The obtained alcohol solution was applied onto a glass plate by a roll coating method and dried at room temperature to form a uniform transparent primary oxide film.

[Reference Example-2] 100 parts by weight of indium sulfate was dissolved in a mixed solvent of 100 parts by weight of ion-exchanged water, 400 parts by weight of methanol and 400 parts by weight of isopropyl alcohol, and 50 parts by weight of ethyl acetoacetate and acetic acid were added.
Add 30 parts by weight and dissolve uniformly. Weakly basic ion exchange resin (trade name: Amberlite IRA-45) 1800
A column filled with a volume part was treated with a flow rate SV20 ^-1 to obtain a pale yellow transparent effluent. Remaining in the effluent ▲ NO ^- ₃ ▼ was observed was analyzed by an ion meter.

It was 49.8% when vacuum-dried and analyzed for In ₂ O ₃ % in the same manner as in Reference Example-1, and In (EA) (OH) ₂ (EA: ethyl acetoacetate
In ₂ O ₃ : 49.9%), and the In (E
It turned out to be A) (OH) ₂ .

This organosol solution formed a transparent indium oxide film when applied to a glass plate and dried.

[Example-1] 20 parts by weight of a tin acetylacetone chelate compound (Sn (AA) ₂ ), 10 parts by weight of maleic acid, and 20 parts by weight of methyl acetoacetate were added to 100 parts by weight of the chelate indium hydroxide sol solution synthesized in Reference Example-1. The composition which was added and dissolved uniformly was light yellow and transparent, and the coating film applied to the soda glass by the roll coating method was easily dried at room temperature to obtain a uniform oxide film. When this was baked at 450 ° C. for 40 minutes, an ITO film having no iris, a sheet resistance of 2 KΩ / □, a visible portion transmittance of 90% or more, and a film hardness and pencil hardness of 9H was obtained.

EXAMPLE -2] Example -2 chelate indium hydroxide sol solution 100 parts by weight of tin methyl acetoacetate chelate compound synthesized in _{(Sn (C 5 H 7 O} 3) 2) 25 parts by weight 10 parts by weight of propionic acid A composition in which 20 parts by weight of acetylacetone was added and uniformly dissolved was transparent in a light yellow color, and was soaked in soda glass by a dipping method.
The coating film applied at a pulling rate of cm / min was easily dried at room temperature to obtain a uniform oxide film. When this was baked at 450 ° C. for 30 minutes, a good ITO film having no iris, a sheet resistance of 3 KΩ / □, a visible part transmittance of 90% or more, and a film hardness of 8H was obtained.

[Brief description of drawings]

The drawing is the infrared spectrum of the organoindium sol obtained in Reference Example 1.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01B 13/00 503 C 7244-5G

Claims (2)

[Claims] 1. A chelating agent selected from β-diketone and β-ketoester is added to a water-soluble lower alcohol solution of an indium compound represented by the general formula InX ₃ (X represents a halogen or a nitrate group), The chelate indium hydroxide type organoindium sol obtained by treating this with a basic ion exchange resin has a Sn / In ratio of 0.5 to 3
A composition for forming a transparent conductive film, which is obtained by adding a divalent tin chelate compound represented by the general formula SnY ₂ (Y represents β-diketone, β-ketoester or N-alkyl group-substituted aminoalcohol) at 0% by weight. 2. A chelating agent selected from β-diketone and β-ketoester is added to a water-soluble lower alcohol solution of an indium compound represented by the general formula InX ₃ (X represents a halogen or a nitric acid group), The chelate indium hydroxide type organoindium sol obtained by treating this with a basic ion exchange resin has a Sn / In ratio of 0.5 to 3
A composition for forming a transparent conductive film obtained by adding a divalent tin chelate compound represented by the general formula SnY ₂ (Y represents β-diketone, β-ketoester or N-alkyl group-substituted aminoalcohol) at 0% by weight. A transparent conductive film obtained by coating on a substrate and baking.