JP2005108728A - Treating agent for forming transparent conductive film and method for forming transparent conductive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating agent for a transparent conductive film, dissolving each compounding agent, and having high permeability and a low resistance value, and a method for forming the transparent conductive film. <P>SOLUTION: (1) An indium compound and (2) a tin compound are added to a mixed solvent obtained by dissolving acetylacetone, carbitol, and/or ester by stirring them. and the mixed solvent is kept at 80-180°C, and it is cooled after dissolving the indium compound and the tin compound. This solution is kept at about 50-80°C, and nitrocellulose forming a thickener is dissolved in it to make this treating agent for the transparent conductive film. In addition, preferably, ethyl carbitol is used as carbitol and butyl lactate is used as ester. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a transparent conductive film forming treatment agent and a transparent conductive film forming method used for liquid crystal displays, touch panels, solar cells and the like.

  As a method for producing a transparent conductive film, 1) a vapor deposition method such as a method of directly depositing tin oxide or the like on a substrate, a method of forming a film by sputtering using ITO or the like, a CVD method using a metal alkoxide, 2) Coating methods such as a method in which an organic salt of tin or indium is applied to a substrate and thermally decomposed, and a method in which an ink containing conductive fine particles is printed or applied are known. However, 1) gas phase methods such as sputtering and CVD require a large apparatus and have poor productivity, and in recent years, 2) coating methods have attracted attention.

As a treatment agent used in such a coating method, a tin compound for adjusting resistance and a nitrocellulose as a viscosity agent are added to an indium compound, and a mixed solvent of butyl cellosolve, butyl carbitol, benzyl acetate and dimethyl phthalate is added and mixed as a solvent. A transparent conductive film-forming paste obtained in this manner is disclosed. (For example, see Patent Document 1)
Japanese Examined Patent Publication No. 63-25448

  In the above invention, cellsolve or carbitols that dissolve nitrocellulose well are used in order to improve the poor screen printability and short life caused by nitrocellulose. There was a problem that the solubility of the compound was poor and it was difficult to increase the metal concentration in the treatment agent.

  As a result of intensive studies in view of the above problems, a transparent conductive film forming treatment agent and a transparent conductive film forming method that dissolve each compounding agent well, have high transmittance, and have a low resistance value are provided.

  That is, the present invention relates to (1) an indium compound, (2) a tin compound, (3) a thickener, and (4) a treatment agent for forming a transparent conductive film containing an organic solvent. A processing agent for forming a transparent conductive film, characterized in that it is nitrocellulose and (4) the organic solvent is a mixed solvent of acetylacetone and carbitol and / or ester. The present invention is also the transparent conductive film forming treatment agent, wherein carbitol is ethyl carbitol; the ester is acetate ester and / or lactic acid ester; the treatment agent for transparent conductive film formation, wherein the ester is butyl lactate. It is. Furthermore, the present invention is a method for forming a transparent conductive film, wherein the transparent conductive film forming treatment agent is applied to a substrate, dried and then fired.

  According to the present invention, by using a specific organic solvent in combination, there is an effect that each compounding agent is well dissolved and the stability of the treatment agent is excellent. Moreover, the transparent conductive film produced with this processing agent has characteristics such as high transmittance and low resistance.

  The processing agent for forming a transparent conductive film according to the present invention contains (1) an indium compound, (2) a tin compound, (3) a thickener, and (4) an organic solvent, and (3) the thickener is nitro. Cellulose, wherein (4) the organic solvent is acetylacetone and carbitol and / or ester.

  (1) The indium compound is an organic indium compound, and examples thereof include alkoxides such as ethoxide of indium, propoxide and butoxide, chelates such as acetylacetonate, and organic acid esters such as stearate, octylate and naphthenate.

  (2) The tin compound is an organic tin compound, and examples thereof include alkoxides such as tin ethoxide, propoxide and butoxide, chelates such as acetylacetonate, and organic acid esters such as stearate, octylate and naphthenate.

  The amount of addition of (1) indium compound and (2) tin compound is not limited, but considering the film thickness, each of the treatment agents contains 1 to 10% by weight of the total metal content of indium and tin. It is preferable to add a compound. Further, it is desirable that tin / (indium + tin) = 5-50 in terms of atomic weight ratio, and in order to obtain a lower resistance film, it is desirable to set the numerical value to 8-10. The resistance value of the film can be controlled by changing the amount of tin.

  The (3) thickener used in the present invention is nitrocellulose, which has an effect of obtaining a transparent conductive film having high transparency and a low resistance value. The amount added varies depending on the molecular weight of the nitrocellulose used and (4) organic solvent species described later, but it is preferably contained in the treating agent in an amount of 1 to 10% by weight. If it is less than 1% by weight, it is difficult to increase the thickness, and the resistance value of the transparent conductive film after firing is not satisfactory. If it exceeds 10% by weight, the thermal decomposability will deteriorate during firing, and the physical properties of the transparent conductive film after firing will deteriorate. Moreover, although molecular weight is not specifically limited, The thing of 10,500-126,000 is used preferably.

  The organic solvent (4) used in the present invention is a mixed solvent of acetylacetone and carbitol and / or ester. Acetylacetone dissolves the indium compound and carbitol and / or ester dissolves nitrocellulose, which is a thickener. Examples of the carbitols include ethyl carbitol, butyl carbitol, and the like. Among them, ethyl carbitol having a higher boiling point is preferably used.

  Esters are preferably acetates and lactates, and more specifically include ethyl acetate, butyl lactate, and ethyl lactate. Of these, butyl lactate having a higher boiling point is preferred.

  The amount of the mixed solvent of acetylacetone and carbitol and / or ester is determined depending on the type and amount of the indium compound and nitrocellulose, but 500 to 3000 parts by weight of acetylacetone is added to 100 parts by weight of the indium compound. The amount of carbitol or ester added is preferably 200 to 8000 parts by weight with respect to 100 parts by weight of nitrocellulose.

  Although the preparation method of the processing agent for transparent conductive film formation is not limited, an indium compound and a tin compound are added to a mixed solvent obtained by stirring and dissolving a desired organic solvent, and maintained at 80 to 180 ° C., The indium compound and the tin compound are dissolved and then cooled. This solution is kept at about 50 to 80 ° C., and nitrocellulose as a thickener is dissolved to obtain a target treatment agent for forming a transparent conductive film.

  The transparent conductive film is produced by, for example, applying the transparent conductive film forming treatment agent on a glass substrate made of soda lime glass, quartz glass, or non-alkali glass by a method such as spraying, dipping, roll coating, or spin coating. Then, after drying the organic solvent in an oven at 50 to 150 ° C., it is baked for 10 to 50 minutes in an oxygen-existing environment, for example, in a furnace at 500 to 800 ° C. in air, and after cooling, the transparent conductive film Can be obtained.

Examples 1-7
Install a propeller stirrer and a stirring vessel in a water bath whose temperature is adjusted to 80 ° C., mix acetylacetone with carbitol or ester according to the blending amount shown in Table 1, and then add indium compound and tin compound to this mixed solvent. Added and dissolved. In this solution, Examples 1 to 3 and 7 were used as thickeners, high molecular weight nitrocellulose (RS-120 manufactured by Daicel Chemical Industries, Ltd .: Mw 10,500 to 126,500), and Examples 4 to 6 were used as thickeners. , Low molecular weight nitrocellulose (SS-20 manufactured by Daicel Chemical Industries, Ltd .: Mw 66,000-76,000) was dissolved. Then, each treatment agent was produced by naturally cooling to room temperature.

  Using these treatment agents, a soda lime glass plate having a thickness of 3.0 mm was applied by spin coating (1000 rpm × 10 s + 2000 rpm × 20 s), and the coated glass plate was dried at 100 ° C. for 10 minutes, and then 600 ° C. The glass with a transparent conductive film was produced by baking for about 10 minutes in a belt furnace. 1-3 evaluation was implemented about the obtained glass with a transparent conductive film.

1. Electrical characteristics Using Loresta FP (manufactured by Mitsubishi Chemical Corporation), electrical characteristics of the glass with a transparent conductive film were measured by a four-point probe method.

2. Film thickness The film thickness of the transparent conductive film was measured using a stylus-type film thickness meter.

3. Optical characteristics To determine the transparency of the glass with a transparent conductive film, the Hz rate and transmittance were measured using a turbidimeter (manufactured by Nippon Denshoku) and a spectrophotometer (manufactured by Shimadzu UV3100).

From Table 1, the obtained transparent conductive film had a haze ratio of less than 0.5% regardless of the molecular weight of nitrocellulose, and exhibited a high transmittance. It was also found that the volume resistivity was as low as 10 ⁻³ Ωcm.

Comparative Examples 1 and 2
A propeller stirrer and a stirring vessel were installed in a water bath whose temperature was adjusted to 80 ° C., an organic solvent was prepared according to the blending amount shown in Table 2, and an indium compound and a tin compound were added to the organic solvent and dissolved. . In this solution, as a thickener, Comparative Example 1 was dissolved using ethyl cellulose, and Comparative Example 2 was an acrylic resin. Then, each treatment agent was produced by naturally cooling to room temperature.

  Using these treatment agents, a soda lime glass plate having a thickness of 3.0 mm was applied by spin coating (1000 rpm × 10 s + 2000 rpm × 20 s), and the coated glass plate was dried at 100 ° C. for 10 minutes, and then at 600 ° C. The glass with a transparent conductive film was produced by baking for about 10 minutes in a belt furnace. 1-3 evaluation was implemented about the obtained glass with a transparent conductive film.

  From Comparative Example 1, when ethyl cellulose is used, the haze ratio is low and the transmittance is high, but the volume resistivity is inferior to the ink using nitrocellulose. Further, it can be seen from Comparative Example 2 that when an acrylic resin is used, the volume resistivity is worse and the haze ratio is higher than that of the ink using nitrocellulose.

The treatment agent for forming a transparent conductive film and the method for forming a transparent conductive film according to the present invention are applied to a liquid crystal display, a touch panel, a solar battery, a heating element for preventing defogging of glass such as buildings and vehicles, and the like.

Claims (5)

  (1) Indium compound, (2) Tin compound, (3) Thickener, and (4) Transparent conductive film forming treatment agent containing organic solvent, (3) Thickener is nitrocellulose, (4) The processing agent for forming a transparent conductive film, wherein the organic solvent is a mixed solvent of acetylacetone and carbitol and / or ester.   The treatment agent for forming a transparent conductive film according to claim 1, wherein the carbitol is ethyl carbitol.   The treatment agent for forming a transparent conductive film according to claim 1 or 2, wherein the ester is an acetate ester and / or a lactic acid ester.   The treatment agent for forming a transparent conductive film according to claim 1, wherein the ester is butyl lactate. The transparent conductive film formation method characterized by apply | coating the processing agent for transparent conductive film formation in any one of Claims 1-4 to a board | substrate, baking after drying.