JP2005125305A - Treating agent and method for forming transparent electrically-conductive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a treating agent for forming a transparent electrically-conductive film, the compounding agents of which are satisfactorily dissolved, and which has high transmissivity and a low resistance value, and to provide a method for forming the transparent electrically-conductive film. <P>SOLUTION: The objective treating agent for forming the transparent electrically-conductive film is obtained by: adding an indium compound (1) and a tin compound (2) to a mixed solvent in which phenols and a dibasic acid ester are dissolved by agitating them; dissolving the indium compound (1) and the tin compound (2) into the mixed solvent by keeping the mixed solvent at 80-180°C; cooling/keeping the indium compound (1)/tin compound (2)-dissolved mixed solvent at about 50-80°C; and dissolving nitrocellulose (3) being a thickener in the indium compound (1)/tin compound (2)-dissolved cooled mixed solvent. It is desirable to add an olefin-based solvent to the nitrocellulose-added mixed solvent, if necessary. It is preferable that at least one selected from the group consisting of cresol, xylenol and ethylphenol is used as the phenols and diethyl malonate is used as the dibasic acid 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 phenols and dibasic acid esters. The present invention also provides the transparent conductive film forming treatment agent, wherein the phenol is selected from the group consisting of cresol, xylenol, and ethylphenol; the dibasic acid ester is diethyl malonate; 4) The organic solvent is a mixture obtained by further mixing an olefin solvent; (4) The organic solvent is a treatment agent for forming a transparent conductive film, which is a mixture obtained by further mixing a lower alkyl ester of a lower fatty acid. 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. Furthermore, when an olefin solvent is used in combination, workability such as printability is improved, and a transparent conductive film having a lower resistance value is obtained. Further, when a lower alkyl ester of a lower fatty acid is used in combination, the solubility of nitrocellulose increases, and a high-viscosity treatment agent can be obtained.

  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 a phenol and a dibasic acid ester.

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

  (2) The tin compound is preferably an organic tin compound, and includes alkoxides such as tin ethoxide, propoxide and butoxide, chelates such as acetylacetonate, and organic acid salts such as stearate, octylate and naphthenate. It is done.

  The contents of (1) indium compound and (2) tin compound are 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 weight ratio, and in order to obtain a lower resistance film, the weight ratio is desirably 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 content varies depending on the molecular weight of the nitrocellulose used and (4) the type of organic solvent described later, but is preferably contained in the treatment 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. When it exceeds 10% by weight, the thermal decomposability of the resin is deteriorated during firing, and the physical properties of the transparent conductive film after firing are deteriorated. Moreover, although molecular weight is not specifically limited, The thing of 10,500-126,000 is used preferably. Nitrocellulose acts not only as a thickener but also as a binder.

  (4) The organic solvent used in the present invention is a mixed solvent of phenols and dibasic acid esters. Examples of the phenols include cresol, xylenol, ethylphenol, chlorophenol, pt-butylphenol, octylphenol, and the like. Among them, cresol, xylenol, and ethylphenol are preferable in view of thermal decomposability. Phenols can dissolve indium compounds when used in combination with dibasic acid esters.

  Examples of the dibasic acid ester include diethyl malonate, dimethyl phthalate, dimethyl glutarate, dimethyl 3-oxoglutarate, and the like. However, diethyl malonate having excellent solubility in terms of structure is preferable. A dibasic acid ester can dissolve an indium compound by using it together with phenols, and can dissolve nitrocellulose.

  The mixing ratio of the mixed solvent of phenols and dibasic acid ester is preferably 18 to 1: 1 to 18 in terms of mass ratio of the former: the latter, and the contents of both in the treating agent are indium compound, nitro Although it is determined by the type and content of cellulose, the content of phenols is preferably 50-1500 parts by weight with respect to 100 parts by weight of the indium compound. The dibasic acid ester is desirably contained in an amount of 100 to 9500 parts by weight based on 100 parts by weight of nitrocellulose.

  In addition to the solvent, an olefin solvent can be added. The olefin solvent is an organic solvent that does not dissolve nitrocellulose, but by adding to the treatment agent, it is possible to improve the printability of the treatment agent and further reduce the resistance value of the resulting film. The content is determined by phenols, dibasic acid esters, lower alkyl esters of lower fatty acids described below, and (3) the type and content of nitrocellulose. The remarkable effect is acquired by containing -20weight%. Examples of the olefin solvent include pentene, hexene, heptene octene, decene, and dodecene. Among these, dodecene is preferably used.

  Moreover, in addition to the said solvent, the lower alkyl ester of a lower fatty acid can be added. Since lower alkyl esters of lower fatty acids are good solvents for nitrocellulose, the solubility of nitrocellulose is increased, the viscosity of the treatment agent can be increased, and the composition is suitable for screen printing. Examples of the lower alkyl ester of the lower fatty acid include acetic acid ester and lactic acid ester. Among them, lactic acid ester is preferably used since it has a high boiling point. Examples of the lactic acid ester include methyl lactate, ethyl lactate, and butyl lactate, among which butyl lactate having a high boiling point is preferably used. Its content is determined by the indium compound, tin compound, phenols, dibasic acid ester, olefinic solvent, and (3) the type and content of nitrocellulose. The remarkable effect is acquired by making it contain 0 to 50 weight% in.

  Although the adjustment method of the processing agent for transparent conductive film formation is not limited, Specifically, the following two types of adjustment methods can be illustrated.

  As a first preparation method, an indium compound and a tin compound are added to a mixed solvent obtained by stirring and dissolving a desired organic solvent, and kept at 80 to 180 ° C., and then the indium compound and the tin compound are dissolved and then cooled. To do. 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. In addition, when adding an olefin solvent, it is desirable to mix | blend after adding nitrocellulose. According to this adjustment method, there is an advantage that ink can be produced by a simple process.

  As a second adjustment method, an indium compound and a tin compound in a mixed solvent obtained by stirring and dissolving a desired organic solvent are added, and kept at 80 to 180 ° C., and then the indium compound and the tin compound are dissolved and then cooled. This is the premixture. At this time, as the mixed solvent, the ester solvent does not mix the total amount to be added to the treating agent. The remaining ester-based solution is maintained at about 50 to 80 ° C., and after dissolving nitrocellulose as a thickener, the premixture is added and stirred to obtain a target treatment agent for forming a transparent conductive film. In addition, when adding an olefin solvent, it is desirable to mix | blend after adding nitrocellulose. According to this preparation method, there is an advantage that nitrocellulose can be dissolved in a short time.

  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 1-5, Comparative Examples 1-4
According to the composition of Table 1 and Table 2, an indium compound and a tin compound were added to each organic solvent, and the solution in which nitrocellulose was dissolved after stirring at 170 ° C. for 1.5 hours was visually inspected for the presence or absence of the indium compound. And the solubility was evaluated. In addition, the mixing | blending% of Table 1 and Table 2 is weight%.

  From Examples 1 to 5 in Table 1, it can be seen that when a mixed solvent of a dibasic acid ester and a phenol is used, an organic indium compound, an organic tin compound, and nitrocellulose are well dissolved. From Examples 1 to 4, it was found that each organic solvent alone showed undissolved undissolved indium compound and poor solubility. In Comparative Example 3, salicylaldehyde was used in place of phenols, and in Comparative Example 4, benzyl alcohol was used in place of dibasic acid ester, but both had problems with solubility.

Examples 6 and 7
A flask and a reflux tube were installed on a hot stage whose temperature was adjusted to 180 ° C., and after mixing a dibasic acid ester and a phenol according to the blending amounts shown in Table 3, an indium compound and a tin compound were mixed in this mixed solvent. Was added and stirred for about 1 hour to dissolve. After this solution was naturally cooled, it was kept at about 80 ° C., and high molecular weight nitrocellulose (RS-120 Daicel Chemical Industries, Ltd .: Mw 10,500 to 126,500) was dissolved as a thickener. Then, each treatment agent was produced by naturally cooling to room temperature. In Table 3, the blending percentage is weight percent.

  Using these treatment agents, a soda lime glass plate having a thickness of 3.0 mm was applied by screen printing, and the coated glass plate was dried at 100 ° C. for 10 minutes, and then in a belt furnace at 600 ° C. for about 10 minutes. Baking was performed to produce a glass with a transparent conductive film. 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 3, it was found that the obtained transparent conductive film had a haze ratio of less than 0.5% and exhibited high transmittance. It was also found that the volume resistivity was as low as 10 ⁻³ Ωcm.

Examples 8-11
A flask and a reflux tube were placed on a hot stage whose temperature was adjusted to 180 ° C., and an organic solvent was mixed in accordance with the recipe shown in Table 4, and then an indium compound and a tin compound were added and dissolved. After naturally cooling this solution, it is kept at 80 ° C., and a high molecular weight nitrocellulose (RS-120 Daicel Chemical Industries, Ltd .: Mw 10,500 to 126,500) is dissolved as a thickener. Dodecene was added as a solvent. Then, each treatment agent was produced by naturally cooling to room temperature. In Table 4, the blending percentage is% by weight.

  Using these treatment agents, a soda lime glass plate having a thickness of 3.0 mm was applied by screen printing, and the coated glass plate was dried at 150 ° C. for 10 minutes and then baked in a belt furnace at 520 ° C. for about 20 minutes. Thus, a glass with a transparent conductive film was produced. 1-3 evaluation was implemented about the obtained glass with a transparent conductive film.

From Table 4, the obtained transparent conductive film had a haze ratio of less than 0.5% and a high transmittance. Further, it was found that the resistance value can be lowered by adding dodecene, and a low volume resistivity on the order of 10 ⁻³ Ωcm is exhibited.

Examples 12-15
According to the composition of Table 5, a transparent conductive film-forming treatment agent was prepared, and the solubility of nitrocellulose was visually evaluated.
As a method for producing the transparent conductive film forming treatment agent, a flask, a reflux tube, and a thermometer were installed in an oil bath whose temperature was adjusted to 120 ° C., and according to the recipe shown in Table 5, an organic solvent, an indium compound, The tin compound was weighed and stirred. When the liquid temperature reached 120 ° C., it was held for 1 hour, dissolved, and then naturally cooled to prepare a premixture. On the other hand, high molecular weight nitrocellulose (RS-120, manufactured by Daicel Chemical Industries, Ltd .: Mw 10,500 to 126,500) is added to an ester solvent maintained at 80 ° C. and dissolved, and then a premixture is added and stirred. did. Then, each processing liquid was produced by naturally cooling to room temperature. In addition, the compounding% of Table 5 is weight%.

  As a result, it was found that a larger amount of nitrocellulose can be dissolved in the examples in which butyl lactate was blended.

Examples 16-21
A flask, a reflux tube, and a thermometer were installed in an oil bath whose temperature was adjusted to 150 ° C., and an organic solvent, an indium compound, and a tin compound were weighed and stirred according to a recipe shown in Table 5. When the liquid temperature reached 150 ° C., it was held for 1 hour, dissolved, and then naturally cooled to prepare a premixture. On the other hand, nitrocellulose was added to butyl lactate maintained at 80 ° C. and dissolved, and then a premixture was added and stirred. Thereafter, each treatment liquid was produced by naturally cooling to room temperature. In Table 6, the blending percentage is weight percent.

  Using these treatment agents, a soda lime glass plate having a thickness of 3.0 mm was applied by screen printing, and the coated glass plate was dried at 100 ° C. for 10 minutes and then baked in a belt furnace at 520 ° C. for about 20 minutes. Thus, a glass with a transparent conductive film was produced. About the obtained glass with a transparent conductive film, the above-described evaluations 1 to 3 were performed.

From Table 6, it was found that the obtained transparent conductive film had a haze ratio of less than 0.5% and a high transmittance. It was also found that a low volume resistivity of the first half of 10 ⁻² Ωcm was exhibited.

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 (6)

  (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 phenols and dibasic acid esters.   The processing agent for forming a transparent conductive film according to claim 1, wherein the phenol is selected from at least one selected from the group consisting of cresol, xylenol, and ethylphenol.   The processing agent for forming a transparent conductive film according to claim 1 or 2, wherein the dibasic acid ester is diethyl malonate.   (4) The processing agent for forming a transparent conductive film according to any one of claims 1 to 3, wherein the organic solvent is a mixture of an olefin solvent.   (4) The processing agent for forming a transparent conductive film according to any one of claims 1 to 4, wherein the organic solvent is further mixed with a lower alkyl ester of a lower fatty acid. A method for forming a transparent conductive film, comprising applying the treatment agent for forming a transparent conductive film according to any one of claims 1 to 5 to a substrate, drying, and baking.