JPH05234432A - Forming method for patterned transparent conductive film - Google Patents

Abstract

PURPOSE:To obtain a transparent conductive film without any pin hole which is uniform in thickness and hard to be deteriorated and excels in transparency. CONSTITUTION:UV hardening masking ink is applied to a substrate and the solvent resistance is increased by UV hardening. An oil film made on a part of the substrate where the masking ink is not applied can be decomposed with oxidation and cleaned for removal due to ozone produced by UV simultaneously with the UV hardening. The application property of a transparent conductive film forming composition is improved by removing the oil film with ozone to extremely reduce a pin hole. The transparent conductive film forming composition including at least an indium compound, tin compound and solvent is applied and heat-treated so that the formation of a transparent conductive film and the removal by thermal decomposition of resin can be simultaneously performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a patterned transparent conductive film on a substrate such as glass or ceramics.

[0002]

2. Description of the Related Art Conventionally, electrodes of display elements such as liquid crystal display elements and electroluminescence (EL) display elements,
BACKGROUND ART Electrode materials having high transparency to visible light are used as members such as heating resistors for preventing fogging or freezing of window glass of automobiles, aircraft, buildings and the like.

As such transparent conductive material, tin oxide / antimony oxide (ATO) and indium oxide / tin oxide (ITO) are known, and these metal oxides are deposited on a glass or ceramic substrate. A film can be easily formed to form a transparent conductive film.

The following methods are known as methods for forming a transparent conductive film. (1) Vacuum evaporation method (2) Sputtering method (3) CVD method (4) Coating method

[0005]

However, the above-mentioned methods (1) vacuum deposition method, (2) sputtering method, (3) CVD method have problems in cost and mass productivity because the apparatus is complicated and expensive. It is difficult to form a complicated pattern in the formation process. Therefore, usually, photolithography or resist printing is performed and a pattern is formed by etching.
Further, although the coating method of (4) has a possibility of solving the problems of the above methods (1), (2), and (3), it is difficult to form a film that can be practically used. Met.

For example, a paste-like composition containing a tin salt and an indium salt of an organic acid containing a photocurable functional group, a composition comprising an inorganic indium salt, an inorganic tin salt, a non-aqueous silica sol and an organic solution of a cellulose compound. The method of screen-printing the above and the method of offset-printing a composition composed of an indium compound, a tin compound, a gum-based natural resin rosin, and a terpene-based high-boiling solvent have the following two problems.

First, there are problems of the screen printing method and the offset printing method, that is, there is a large variation in the film thickness in the solid portion and the thin film thickness in the end portion of the pattern. Secondly, these compositions contain a resin such as a cellulose compound or a gum-based natural resin rosin in order to improve printability, and these are generally likely to remain as free carbon in the film during thermal decomposition, Deterioration of the film properties is unavoidable.

Further, in the method of spin-coating or dip-coating a composition composed of a low-viscosity organic solution containing an organic indium salt and an organic tin salt, it is difficult to form a pattern during the formation process, and insufficient cleaning or oil film However, there is a problem that pinholes are likely to occur due to such reasons.

In consideration of the above problems of the conventional method for forming a transparent conductive film, the present invention provides a high-quality patterned transparent conductive film having no pinhole, no variation in film thickness, and no deterioration in characteristics. An object is to provide a forming method.

[0010]

According to the present invention, a UV curable masking ink is applied onto a substrate, UV curing and ozone cleaning are simultaneously performed, and then a transparent conductive film forming composition is applied and heat treated. It is a method of forming a patterned transparent conductive film including steps.

[0011]

In the present invention, a UV curable masking ink is applied onto a substrate and UV cured to improve solvent resistance.
At the same time as UV curing, ozone generated by UV can oxidatively decompose the oil film formed on the substrate in the portion where the masking ink is not applied, and can be removed and washed. By removing the oil film by this ozone cleaning, the wettability of the composition for forming a transparent conductive film is remarkably improved, and pinholes are extremely reduced.

[0012]

EXAMPLES Examples of the present invention will be described below.

(Example 1) A UV-curable masking ink comprising urethane acrylate, an organic vehicle and an organic solvent was screen-printed on a silica-coated glass substrate to form a pattern having a line width of 2 mm and an interval of 0.5 mm.
After drying at 0 ° C. for 10 minutes, it was cured simultaneously with ozone cleaning using an ozone type high pressure mercury lamp.

Next, a composition for forming a transparent conductive film was synthesized as follows.

In a 1-liter Erlenmeyer flask, 45 g of indium nitrate (Chemical Formula 1) was weighed, 50 g of acetylacetone was added, and they were mixed and dissolved at room temperature.

[0016]

[Chemical 1]

In the solution, 2.7 g [10 wt% in (Equation 1)]
Stannous oxalate (Chemical Formula 2) and acetone were added and refluxed.

[0018]

[Equation 1]

[0019]

[Chemical 2]

The solution after the reflux was cooled to around room temperature, 10 g of glycerin was added, and the mixture was stirred and mixed to obtain a desired composition for forming a transparent conductive film.

The transparent conductive film-forming composition was spin-coated on a masked silica-coated glass substrate. The substrate was left at room temperature for 5 minutes, dried at 100 ° C. for 5 minutes, and then baked at 500 ° C. for 1 hour.

Example 2 A UV curable masking ink comprising an epoxy acrylate, an organic vehicle and an organic solvent was used. Others are the same as in the first embodiment.

Example 3 A composition for forming a transparent conductive film was prepared by
Dip coating was performed on a masked silica-coated glass substrate. Others are the same as in the first embodiment.

(Comparative Example 1) In a 1 l Erlenmeyer flask, 45 g
10 wt% of indium nitrate (Chemical formula 1) and 5.4 g [(Equation 1)]
%] Of stannous chloride (Chemical Formula 3), α-terpineol and nitrocellulose were added, and the mixture was stirred and mixed to synthesize a transparent conductive film-forming composition.

[0025]

[Chemical 3]

The transparent conductive film-forming composition was screen-printed on a silica-coated glass substrate to give a line width of 2 mm.
A pattern with 0.5 mm intervals was formed. The substrate was left at room temperature for 5 minutes, dried at 100 ° C. for 10 minutes, and then baked at 500 ° C. for 1 hour.

Comparative Example 2 A UV-curable masking ink was screen-printed to form a pattern on a glass substrate, dried at 60 ° C. for 10 minutes, and then only cured using an ozoneless type high-pressure mercury lamp. .. Others are the same as in the second embodiment.

Table 1 shows the results of Examples 1 to 3 and Comparative Examples 1 and 2.

[0029]

[Table 1]

As is apparent from this table, the examples of the present invention are far superior to the comparative examples.

As described above, the UV-curable masking ink need only contain a compound having a functional group that is cured by UV, and epoxy (meth) acrylate or urethane (meth) acrylate is preferable. Further, as a method for forming a negative pattern resin film for a desired pattern, a method for directly forming a pattern by screen printing or an offset printing method, or a roll coating, a spin coating or a dip for a photocurable resin is used. A method of forming a pattern by photolithography after coating is mentioned, but a method using screen printing or offset printing is preferable in terms of productivity and cost.

Then, a transparent conductive film forming composition comprising at least an indium compound, a tin compound and a solvent is applied and heat-treated to simultaneously form the transparent conductive film and remove the resin by thermal decomposition. Here, for the coating of the composition for forming a transparent conductive film, a screen printing method, a roll coating method, a dip coating method, a spin coating method or the like can be used, but a dip coating method or a spin coating method is preferable. The firing temperature may be higher than or equal to the temperature at which the composition for forming a transparent conductive film and the resin are decomposed, and lower than or equal to the deformation temperature of the substrate, preferably 400 to 700 ° C.

In the present invention, screen printing, offset printing or the like is used when forming a negative pattern resin film, and a dip coating method, a spin coating method or the like is used to apply the composition for forming a transparent conductive film. Therefore, the variation in the film thickness of the solid portion of the transparent conductive film is small, and the film thickness of the end portion of the pattern is almost the same as the film thickness of the solid portion. Also,
Since the composition for forming a transparent conductive film does not contain any resin that tends to remain as free carbon during thermal decomposition, the properties of the obtained transparent conductive film are good.

[0034]

As is clear from the above description,
The present invention comprises a step of applying a UV-curable masking ink on a substrate, a step of simultaneously performing UV curing and ozone cleaning, and a step of subsequently applying a composition for forming a transparent conductive film,
Since it has a step of heat treatment, it is possible to easily obtain a patterned transparent conductive film without pinholes,
Suitable for transparent electrodes such as display elements and heating resistors.

Further, according to the present invention, it is possible to obtain a transparent conductive film having excellent conductivity and transparency in the visible region.

Further, the present invention has the characteristic of being less likely to deteriorate.

Further, according to the present invention, it is possible to obtain a transparent conductive film having no variation in film thickness.

Claims (3)

[Claims] 1. A step of applying a UV curable masking ink on a substrate, a step of simultaneously performing UV curing and ozone cleaning, and a step of subsequently applying a transparent conductive film forming composition.
A method of forming a patterned transparent conductive film, which comprises a step of heat treatment. 2. A UV curable masking ink comprising at least epoxy acrylate, epoxy methacrylate,
The method for forming a patterned transparent conductive film according to claim 1, comprising either urethane acrylate or urethane methacrylate. 3. The method for forming a patterned transparent conductive film according to claim 1, wherein the composition for forming a transparent conductive film contains at least an indium compound, a tin compound and a solvent.