JPS6319713A - Paste-like composition for formation of transparent conductive film and formation method of transparent conductive film - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a composition for forming a transparent conductive film, and more specifically to an indium oxide-tin oxide composite film (rlTOI).
The present invention relates to a paste composition suitable for forming a patterned transparent conductive film (denoted as llJ) on a heat-resistant substrate, and a method for forming the patterned transparent conductive film.

The present invention can be suitably used for manufacturing transparent electrodes for various displays, solar cells, and the like.

[Conventional technology]

Traditionally, as a manufacturing method for transparent electrodes for various displays, solar cells, etc., a transparent conductive film is formed on a transparent substrate such as glass by a vacuum evaporation method, a sputtering method, a chemical vapor deposition method, a coating and baking method, etc., and then etched. Patterning methods are known, and methods of etching a transparent conductive film formed by vacuum evaporation or sputtering are generally put into practical use.

In recent years, with the aim of omitting the etching process for transparent illumination films, various methods have been investigated in which a paste-like composition for forming a transparent conductive film is patterned and applied to a glass substrate, etc. using a screen printing method, etc., and then baked. ing. For example, a paste composition for forming an ITO film consisting of an organic indium complex, an organic tin complex, nitrocellulose as a binder, and a solvent (Japanese Patent Laid-Open No. 57-27505)
, an indium nitrate derivative, a tin alkyl nitrate derivative, a cellulose derivative, and an organic) pasty composition for forming an ITO film, and after screen printing this composition, irradiation with ultraviolet rays while heating, followed by firing and annealing. Method for forming a patterned transparent conductive film
No. 212268) and the like are disclosed.

[Problem that the invention seeks to solve]

As a manufacturing method for transparent electrodes, the above-mentioned methods that are generally put into practical use have low productivity because they use high-vacuum equipment to form a transparent conductive film, and they also require an etching process to pattern the transparent conductive film. Requires. The resulting products are therefore extremely expensive.

On the other hand, in the method of forming a transparent conductive film patterned by screen printing or the like using the paste composition to form a transparent electrode, the sheet resistance value is 1 to 2 and the patterning is about Ω/sq. However, these ITO films have insufficient adhesion to the substrate and have a high sheet resistance value for use in transparent electrodes of LCDs.

The present invention provides a stable transparent conductive film-forming paste composition suitable for forming a patterned ITO film with a low sheet resistance value and excellent adhesion to a substrate, and a patterned ITO film. The purpose is to provide a method for forming.

Means for Solving Problem C] As a result of intensive research to achieve the above object, the present inventors have developed a paste composition that uses an indium compound and a tin compound as main ingredients for forming an ITO film, and an aromatic nitro compound and an aromatic nitro compound. lTa1l, which is formed by applying a composition containing a cellulose derivative to a heat-resistant substrate by screen printing and then performing preheating treatment and main firing, has excellent adhesion to the substrate and a low sheet resistance value. They discovered this and completed the present invention.

The present invention is characterized by containing an organic indium compound, a tin compound, a cellulose derivative, and an aromatic nitro compound. The pasty composition for film formation and a heat-resistant substrate are screen-printed, preheated at a temperature of 150 to 350°C, and then fired at a temperature of 450°C or higher in an oxidizing atmosphere. This is a method for forming a transparent conductive film (CITO film) characterized by the following.

In the present invention, the organic indium compound and the tin compound are used to form a transparent indium oxide-tin oxide composite film C by baking.
It is the main ingredient for forming an ITO film.

As the organic indium compound, an organic solvent-soluble compound that generates indium oxide by thermal decomposition can be used.

In particular, it is represented by the following general formula (1)% formula% (1), where X in the formula is a β-diketone such as acetylacetone, benzoylacetone, benzoyltrifluoroacetone, dibenzoylmethane, furoylacetone, trifluoroacetone, etc. and/or β- such as methyl acetoacetate, ethyl acetoacetate, malonic acid diester, etc.
Ketoester residue, Y is a halogen atom, a hydroxyl group,
Alkoxy groups having 1 to 18 carbon atoms such as methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, t-butoxy group, formyl group, acetyl group, propionyl group, butyryl group, valyl group At least one selected from the group consisting of acyl groups having 1 to 18 carbon atoms such as , stearoyl group, benzoyl group, and nitrate ester residues.
An organic indium compound which is a substituent of the species and is a#O is preferably used because it has excellent thermal decomposition properties and solubility in organic solvents. More preferably, 1 mol of an organic indium compound of the general formula (11, in which Y is a water a group, an alkoxy group, and/or an acyl group) and 0.3 to 0.3 to nitric acid have excellent thermal decomposition properties and coating film forming properties. 3.0
Using the reaction product with mol.

On the other hand, the tin compound is a component for doping tin oxide to impart conductivity to the indium oxide thin film. As the tin compound, an organic solvent-soluble divalent or tetravalent tin compound that produces tin oxide by thermal decomposition is used. for example,
Tin halides such as stannous chloride, stannous chloride, stannous bromide, stannous bromide, stannous iodide, stannic iodide, etc., inorganic tin salts such as tin nitrate, dipropyltin, Alkyltins such as tetrapropyltin, tin organic acid salts such as tin acetate, tin benzoate, dibutyltin laurate, tin octenoate, di- or tetra-ethoxytin 1 di- or tetra-propoxytin,
tin alkoxides such as di- or tetra-butoxytin;
Chelate complexes or partial chelate complexes of tin alkoxides and β-diketones or β-ketoesters can be used. Preference is given to using inorganic tin salts, tin organic acid salts and (partial) chelate complexes.

The composition ratio (weight basis) of the indium compound and the tin compound is 0.01≦5nO1/
(SnOz+IntO1)≦0.5, preferably 0.
The range is 02≦Snow/(SnOz+InJx)≦0.3.

The cellulose derivative is used as a thickener to impart thixotropy to a composition containing the indium compound and tin compound as main ingredients for forming an ITO film and to form a paste. Examples of cellulose derivatives used include methylcellulose, ethylcellulose, acetylcellulose, acetylbutylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, benzylcellulose, and nitrocellulose. In particular, a mixture of hydroxypropylcellulose, ethylcellulose, acetylbutylcellulose, nitrocellulose and Sorella is preferably used because it has a large effect of imparting thixotropy to make the composition into a paste even when used in a small amount.

The aromatic nitro compound is a component that assists and accelerates the combustion and thermal decomposition of each of the above components. As an aromatic nitro compound,
Nitrobenzene, dinitrobenzene, trinitrobenzene, nitrotoluene, dinitrotoluene, trinitrotoluene, nitro-1-'7talene, picric acid, nitroanisole, ethyl picrate, trinitrodiphenyl ether, benzyl picrate, picric acid derivatives such as picryl acetate, etc. Picric acid, which is relatively stable and easy to handle, is preferably used.

The composition of the present invention contains a total of 0.5 to 15 parts by weight of an indium compound and a tin compound calculated as metal oxide, 5 to 50 parts by weight of a cellulose derivative, and 1 part by weight of a cellulose derivative, per 100 parts by weight of an organic 1-volume preparation. It is a paste-like composition having thixotropic properties, in which 5 to 100 parts by weight of an aromatic nitro compound is blended to 0 parts by weight.

as a solvent with a boiling point of 100°C or higher, preferably 15°C.
An organic solvent having a temperature of 0° C. or higher is used. For example, alcohols such as butanol, octatool, lauryl alcohol, 2-ethylhexyl alcohol, benzyl alcohol, cyclohexanol, α-terpineol, and ethyl cellosolve.

Cellosolves such as butyl cellosolve, ethylcal,
Carpitols such as bitol, methylcarpitol, butylcarpitol, and ethylene glycol.

A single solvent or a mixture of two or more solvents, such as glycols such as propylene glycol and diethylene glycol, and esters such as ethyl acetoacetate, benzyl acetate, methyl benzoate, dimethyl phthalate, dibutyl phthalate, and ethyl cellosolve acetate. used.

If the total amount of the indium compound and the tin compound is too small, the thickness of the ITO film formed will become thinner, and
If the amount is too large, thin film defects such as cloudiness and cracks are likely to occur in the formed ITOIIQ.

If the amount of the cellulose derivative blended is too small, the effect of imparting thixotropy will not be sufficient, the printing resolution of the composition will decrease, and the formed ITO film will be more likely to cause bleeding or disconnection. Also,
If the amount is too large, the viscosity of the composition increases and the workability of screen printing decreases.

The type of blending of aromatic nitro compounds with cellulose derivatives is influenced by the type of other components used, the type of blending, etc., but if the amount is too low, the effect of promoting combustion and decomposition of the composition will be insufficient. , the adhesion of the formed ITO film to the substrate decreases, and the sheet resistance of the ITO film increases. Moreover, even if it is added in excess, it cannot be expected to increase the effect of promoting combustion and decomposition of the composition. The preferred blending amount of the aromatic nitro compound is based on 100 parts by weight of the cellulose derivative.
It is 10 to 30 parts by weight.

In the present invention, the composition is screen printed,
Patterned and printed on a heat-resistant substrate, 150 to 350
After preheating by holding at a temperature of 5 to 30 minutes at a temperature of
10 at a temperature of 50°C or higher, preferably 500-600°C.
By holding the film for 60 minutes and performing main firing, a patterned transparent conductive film (ITO film) can be formed on the heat-resistant substrate.

Following the main firing, the temperature is 300 to 600°C for 10 minutes in an inert gas and/or reducing gas atmosphere.
By performing a heat treatment after holding for ~60 minutes, the sheet resistance of the formed ITO film can be further reduced.

As the heat-resistant substrate, it is possible to use various types of glass, mica, ceramics, etc. that do not cause cracking or deformation at the main firing temperature. In particular, various types of glass are used for transparent conductive covers, as transparency of the substrate is also required, and more preferably 5i(h, Ti0z,
A soda lime glass substrate precoated with ZrOz, Al2O3, etc. and a composite film thereof is used.

[Function] As described above, the present invention provides a patterned ITO characterized in that a cellulose derivative for making the composition into a paste and an aromatic nitro compound as a combustion and decomposition accelerator are used together. A paste composition suitable for forming a film by a printing method and a method for forming a patterned ITO film using this composition.

The cellulose derivative can provide the thixotropy required for the printability of a pasty composition for screen printing by using a small amount, and can provide a composition with excellent printing resolution. Further, the aromatic nitro compound used in combination promotes and accelerates the thermal decomposition property of the composition.

In addition, in the method of forming an ITO film by two-stage thermal decomposition of pre-heating treatment and main calcination of the present invention, and three-stage thermal decomposition including additional post-heating treatment if desired, the solvent is not evaporated in the pre-heating treatment. In addition, gills with fewer thin film defects such as pinholes caused by thermal decomposition of low molecular weight components are formed,
By the main firing, the remaining components are thermally decomposed to form a composite film of indium oxide and tin oxide, which is further crystallized. Further, since the post-heat treatment is performed in an inert gas and/or reducing gas atmosphere, the number of oxygen vacancies in the formed IT◯ film increases, and the sheet resistance value of the ITO film decreases.

In the present invention, the effect of the composition and the effect of the ITO film forming method act synergistically, and a patterned ITO film with low sheet resistance and excellent adhesion to the substrate has heat resistance. formed on a substrate.

〔Example〕

The present invention will be explained in more detail with reference to Examples and Comparative Examples.

However, the scope of the present invention is not limited in any way by the following examples.

In addition, in the following Examples and Comparative Examples, "parts" and "%" are based on weight unless otherwise specified.

fll Preparation of paste composition for forming transparent conductive film fa
+ Samples (A-1) to (A-4) and comparative sample (C
A-1) The weight ratio of butylcarpitol/benzyl alcohol is 1
Pour 30 parts of a /1 mixed solvent into a flask, add 5.0 parts of indium tris (acetylacetonate), and make 100~
The mixture was heated to 120° C. and dissolved with stirring to obtain a homogeneous solution.

Hydroxypropyl cellulose (trade name: HP C-) 1, manufactured by Nippon Soda) is added to 52 parts of a mixed solvent having the same composition as above.
Gradually add 8.4 parts of hydroxypropyl cellulose at room temperature and keep stirring for about 6 hours to dissolve uniformly.
3.8 parts of picric acid, which is equivalent to 45.2 parts based on 0 parts, was added and dissolved.

9g of the resulting mixture of hydroxypropylcellulose and picric acid? &, the previously prepared indium tris (
A paste composition sample (A-1) was prepared by adding 1.0 parts of dibutyltin dilaurate after 7 parts of acetylacetonate were mixed uniformly by gradually straining.

Also, hydroxypropyl cellulose 10 of picric acid
Paste compositions/samples (A-1) to (A-4) were prepared in which the amount added was changed to 5 parts, 20 parts, and 100 parts relative to 0 part.

Furthermore, for comparison, a paste-like composition/comparative sample (CA-1) in which the addition of picric acid was omitted was prepared.

(bl Samples (A-5) to (A-7) Samples (A-1)
In the preparation of 1.68 parts of p-dinitrobenzene, 1 part of 1,3.5-trinitrobenzene in place of picric acid.
．． 68 parts and 1.68 parts of ethyl picrate were added to prepare paste compositions/samples (A-5) to (A-
7) was prepared.

fcl sample (A-8) and comparative sample (CA-1)
7.44 parts of indium tris (7 cetyl acetonate) and 2.40 parts of concentrated nitric acid were added to 122 parts of a mixed solvent of butyl cellosolve/butyl carpitol/benzyl acetate in a weight ratio of 2/1/1, and the mixture was heated to 60°C for 30 minutes. After stirring and maintaining for a minute, the mixture was cooled and 0.51 part of tinbismethyl acetate was added and uniformly dissolved.

Next, hydroxypropylcellulose (product name/HP
12.0 parts of C-M Nippon Soda M) and 9.3 parts of acetyl butylcellulose were gradually added to the solution prepared above and dissolved uniformly, and then 3.3 parts of acetic acid and krylic were added and mixed. A paste-like composition/sample (A-8) was prepared.

In addition, as a comparative sample, (CA-1) was prepared in which the addition of picryl acetate was omitted.

+d+ Sample (A-9) Butyl calpitol/butyl cellosolve/acetic acid 100 parts of a mixed solvent with a weight ratio of benzyl of 2/1/1,
3.3 parts of indium nitrile lactate synthesized by reacting 1 mole of indium nitrate with 1 mole of lactic acid and 1.8 parts of tinbutoxylactate synthesized by reacting 1 mole of tin tetrabutoxy with 2 moles of lactic acid were added. and dissolved uniformly. Next, hydroxypropyl cellulose
A mixture of 6 parts of RPC-H (mentioned above) and 14 parts of HPC-M (mentioned above) was added to the steel solution, stirred and mixed thoroughly to dissolve uniformly, and then 5 parts of picric acid was added. were added and mixed to prepare a paste composition/sample (A-9).

Table 1 shows the compositions of the samples (A-1) to (A-9) and comparative samples (CA-1) and (CA-1) prepared above.

(1) Formation of transparent conductive film (ITO film) On a soda lime glass substrate, paste composition sample for forming transparent conductive film (ITO film) prepared in the above section f11 (
A-1) pattern with a line width of 25 Qum and a diameter of ¥20 μm was printed using a 300 mesh stainless steel screen, preheated at 150°C for 15 minutes, and then printed using a Matsufuru furnace. , 550 in air atmosphere
After the main firing was carried out under the conditions of 30 minutes at °C, the substrate was naturally cooled to room temperature to obtain a patterned transparent conductive film (CITO film) on the substrate.

The obtained rTo film had a film thickness of 1200 mm and a sheet resistance value of R and Q1 after being left at room temperature for one day. The film was OK Ω/sq without disconnection or bleeding, and the cellophane tape peel test results showed good adhesion.

Further, as a result of post-heating the substrate on which the obtained ITO film was formed under conditions of 350° C. for 30 minutes in a nitrogen gas atmosphere, the sheet resistance value R□ decreased to 0.5 Ω/sq.

Below, soda lime glass substrate, 5iOz coated soda lime glass substrate and 5i (h/ZrO richness=60/40
(weight ratio) of paste composition samples (A-1) to (A-9>) for forming a transparent conductive film (ITO film) and a comparative sample (CA-
1) and (CA-1), 3
Print using a 00 mesh stainless steel screen, perform preheating, main firing, postheating, and cooling using a Matsufuru furnace or an image furnace with an adjustable heating and cooling pattern, and then apply it to the substrate. A patterned transparent conductive IQCITO film was formed.

Table 2 shows the pre-heat treatment conditions, main firing treatment conditions, post-heat treatment conditions, and the characteristics of the formed ITO film.

In Table 2, adhesion, surface hardness and alkali resistance were expressed according to the following criteria.

Adhesion: Those that did not peel off in the cellophane tape peeling test were rated as good.

Surface Hardness 2 The surface was rubbed 20 times with an eraser, and those with no change were marked as △, those with a partial change in Ol, and those with a thin film disappeared as ×.

Alkali resistance: The film was immersed in a 5% aqueous sodium hydroxide solution at 60°C, and the time (minutes) required for the thin film to dissolve was measured and displayed.

〔Effect of the invention〕

In the present invention (as shown in the above examples, the sheet resistance is Patterned transparent conductive film (ITO) with low value
membrane) is obtained. In particular, in the system subjected to backward u'Q treatment, the sheet resistance value R0 is 0.38 KΩ/sq, 0
．． IT0119 with a low See Hff resistance of up to 10Ω/sq, i.e. with high conductivity, is obtained. Moreover, all of these have excellent adhesion to the substrate.

The present invention relates to a paste-like composition for forming a transparent conductive film that provides a patterned transparent conductive film (ITO film) with excellent adhesion to a substrate and a low sheet resistance value, and a transparent conductive film using this composition. It provides a method for forming a film,
Its industrial significance is extremely large.

Claims (1)

[Claims] (1) A paste-like composition for forming a transparent conductive film characterized by containing an organic indium compound, a tin compound, a cellulose derivative, and an aromatic nitro compound. A pasty composition containing a cellulose derivative and an aromatic nitro compound was screen printed, preheated at a temperature of 150 to 350°C, and then heated to 450°C in an oxidizing atmosphere.
A method for forming a patterned transparent conductive film characterized by firing at a temperature higher than or equal to