JPH0528450B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a composition used for forming a transparent conductive film on a substrate, and a method for forming a transparent conductive film, and more specifically relates to a composition for forming a transparent conductive film on a substrate, and more specifically to a composition for forming a transparent conductive film on a substrate. The present invention relates to a solution composition for a transparent conductive film useful for various purposes, and a method for forming the film. [Prior Art] In recent years, attempts have been made to coat the surfaces of various substrates with thin films to impart desired conductive properties to the substrates. Among them, a film made by doping tin oxide with Sb and F is called a NESA film (hereinafter referred to as a NESA film), and refers to a film that is strong, has good transparency, and is electrically conductive, and is usually deposited by PVD or vacuum evaporation. , sputter,
Films are formed by CVD (plasma CVD, thermal CVD), etc. In particular, Nesa membrane, unlike ITO, is better than PVD.
CVD is the mainstream. As a method, Sn(Me) ₂ Cl ₂ ,
There is a method of vaporizing organic tin compounds such as SnCl ₄ and Sn(Me) ₃ Cl and spraying them onto heated glass.
There were problems such as the film formation speed was slow, the film formation equipment was large and expensive, and it was difficult to increase the area and mass production. Therefore, considering the elimination of such drawbacks such as production quality, homogeneity, workability, economic efficiency, etc., we decided to use an organic solvent containing a tin compound as a method to obtain a Nesa film through decomposition heat treatment and provide excellent electrification characteristics. Methods for forming a NESA film using a spray method, a roll coating method, a spin coating method, and a dipping method have been proposed. For example, JP-A-59-198608 discloses a composition consisting of a chlorine-containing tin alkoxide, an antimony compound, a suitable organic solvent, and water, and a film forming method using this composition is as follows. The immersion method is used. [Problems to be solved by the invention] However, in the above invention, substantially completely substituted triethoxyantimony or the like is used as the antimony compound, and water is added to the alkoxide system. It is very difficult to produce compositions with a long pot life, and it is very difficult to obtain reproducible data. It was also found that when a film is formed, the film thickness becomes non-uniform and cloudiness often occurs. Therefore, it is an object of the present invention to provide a composition and a method for forming a conductive film, which can provide a thin film with good conductivity over a wide composition range and a long pot life with good reproducibility. [Means for Solving the Problem] In order to achieve the above object, the present inventors have conducted intensive studies and found that by combining chlorine-containing alkoxides of a specific composition, the pot life is extremely long and reproducible. The present invention was achieved by discovering that a transparent conductive film with excellent conductive properties can be formed. That is, the present invention is based on the general formula Sn(OR ₁ ) _x Cl _ox (wherein R ₁ has a carbon number of 1 to 10
represents an alkyl group or an alkoxyalkyl group, n is 2 or 4, and when n=2, 1.0≦
x≦1.8, 2.5≦x≦3.5 when n=4) and a chlorine-containing tin alkoxide with the general formula Sb(OR ₂ ) _y
Cl _ny (However, R ₂ represents an alkyl group or an alkoxyalkyl group having 1 to 10 carbon atoms, m is 3 or 5, and when m=3, 1.5≦y≦2.8, m=5
In the case of 2.0≦y≦4.8), a chlorine-containing antimony alkoxide with a Sb/Sn molar ratio of 20/80
Using a composition for a transparent conductive film characterized by mixing at a ratio of ≧Sb/Sn≧1/99 and the above composition, it was applied to a substrate, dried at room temperature to 300°C,
This is a method for forming a transparent conductive film, which is characterized by firing at a temperature of ~650°C. The alkyl group used in the present invention has 1 to 10 carbon atoms.
However, it is particularly preferable to have 2 to 5 carbon atoms, and more preferably an alkoxylakyl group. Further, in Sn, n may be 2 or 4, and in Sb, m may be 3 or 5, resulting in four possible combinations, but any of these may be used. The concentration of the composition of the present invention is such that the sum of chlorine-containing tin alkoxide and chlorine-containing antimony alkoxide is 0.05.
~1.5 mol/ is preferred. If the total concentration of both is less than 0.05mol/1
Because the thickness of the film that is applied once is too thin, the number of times of overcoating is too large, and the transparency and conductive properties of the film itself are poor. On the other hand, if the concentration exceeds 1.5 mol/l, the thickness of the coating film formed at one time is too thick, the coating film is likely to crack, and it is difficult to obtain a film with excellent conductive properties. The diluting solvent for adjusting the above concentration may be hydrocarbons such as hexane, heptane, aromatic hydrocarbons such as benzene, toluene, xylene, etc.
- Alcohols such as propanol, i-propanol, n-butanol, i-butanol, acetate esters such as ethyl acetate and butyl acetate, ketones such as diethyl ketone and acetone, THF, chloroform, etc., and dilution with these solvents. After that, the film can be formed under various conditions. As a coating method, a spray method, a roll coating method, a spin coating method, and a dipping method can be used to form a film, and the dipping method is preferable. When applying by dipping method, the pulling speed is 0.1~
0.8cm/sec, the temperature at that time is 15-25℃, the humidity is 60
% or less, especially 40 to 50%. If the pulling speed is lower than 0.1 cm/sec, it is difficult to form a uniform film, and the film formed at one time is too thin, so the number of coatings must be increased, which causes deterioration of the conductive properties. On the other hand, the pulling speed
If it is larger than 0.8 cm/sec, the film formed at one time becomes too thick, which causes cracks in the film, which is not preferable. In addition, conditions such as loss level and humidity during lifting must be strictly controlled because they are greatly affected by the rate of hydrolysis. After forming a film by the above method, it is left at room temperature for about 5 to 10 minutes, and the alkoxide is sufficiently gelled by moisture in the air. Thereafter, drying is performed at 50°C for 10 to 20 minutes to quickly diffuse the solvent. Heat this further to 200-300℃
Free organic matter, remaining solvent, and moisture are scattered by drying for 10 minutes to 1 hour.
At that time, if it is suddenly dried at a temperature of 200℃ or higher,
The film tends to become cloudy and shrink due to the difference in drying speed between the surface and the inside. Finally, by firing at a temperature of 500 to 650°C, organic substances are scattered by oxidative decomposition, and metals also become oxides. Further, a more preferable temperature is 550 to 600°C, and the electrical conductivity is highest within this range, and both lower and higher temperatures than this range are undesirable because the electrical conductivity decreases. Normally, by drying at 200°C and then firing at 500 to 650°C, the film thickness will shrink by 20 to 40%, so it is necessary to form a film that is 30 to 40% thicker before drying. The film thickness can be adjusted by the number of repetitions of coating and drying and the concentration of the coating liquid. In addition to various types of glass, the substrate used in the present invention may be made of ceramic such as alumina. Note that when soda lime glass is used, a silica undercoat is required before forming the NESA film in order to prevent sodium and potassium ions from diffusing into the film. [Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. Example 1 Sn(0-i-Pr) ₃ Cl was added to the 2-necked flask.
0.392 mol of was taken, and a mixed solution of isopropyl alcohol and ethyl cellosolve (1+1) was added thereto to make 1. Furthermore, pre-synthesized Sb(0-i
-Am) ₄ Cl was added dropwise in an amount of 0.008 mol to prepare a homogeneous solution. This solution remained stable for more than 6 months without causing any gelation, even when the container was left in contact with the atmosphere without a lid. Furthermore, using this solution, using soda lime glass (100 x 100) as a substrate, after thoroughly cleaning the surface and pre-coating with silica (approximately 1000 Å), it was applied by dipping at a pulling speed of 0.4 cm/sec. . After that, leave it indoors for 10 minutes, then heat it at 50℃ for 10 minutes.
It was dried at 200° for 10 minutes and finally fired for 10 minutes. Table 1 shows the liquid composition of the solution used and the physical properties of the obtained membrane. Regarding the properties of the film, tests were conducted on translucency, strength, and adhesion, and those with good properties were marked as ○, and those with cracks, cloudiness, peeling, etc. were described in detail. This also applies to the comparative example (Table 2). Examples 2 to 8 The composition of tin alkoxide and antimony alkoxide, the molar ratio (Sb/Sn), the type and concentration of the diluting solvent were changed, and the other conditions were kept the same, and the film composition was adjusted and the film formation was performed. I went. When two types of diluent solvents were used, it was a 1:1 mixed solution, and the same was true for the comparative example. The conditions and results of this experiment are shown in Table-1.
The solution used in this example also had a pot life of 6 months or more. Comparative Examples 1 to 5 The changed conditions and the way the tables are presented are exactly the same as in the examples. The conditions and results are shown in Table 2. The pot life of the solutions in Comparative Examples 1, 2, and 5 was very short, and the solutions became cloudy or formed a precipitate within one month. On the other hand, in Comparative Examples 3 and 4, the pot life of the solution was sufficient at 6 months or more, but the properties of the membrane were poor.

【table】

[Table] [Effects of the Invention] The composition of the present invention has a very long pot life compared to conventional chemical solutions, and when used as a coating solution to form a film, it has excellent conductivity, translucency, film strength, etc. with good reproducibility. An excellent transparent conductive film can be obtained. Further, by combining it with an alkoxide containing another metal, properties such as film strength can be further improved.

Claims (1)

[Claims] 1 General formula Sn(OR ₁ ) _x Cl _ox (wherein R ₁ represents an alkyl group or an alkoxyalkyl group having 1 to 10 carbon atoms, n is 2 or 4, and n=2 case
1.0≦x≦1.8, 2.5≦x≦3.5 when n=4) and a chlorine-containing tin alkoxide with the general formula Sb
(OR ₂ ) _y Cl _ny (However, R ₂ represents an alkyl group or an alkoxyalkyl group having 1 to 10 carbon atoms, m is 3 or 5, and when m = 3, 1.5≦y≦2.8,
When m = 5, the chlorine-containing antimony alkoxide shown by 2.0≦y≦4.8) is
A composition for a transparent conductive film, characterized in that it is mixed at a ratio of 20/80≧Sb/Sn≧1/99. 2 General formula Sn(OR ₁ ) _x Cl _ox (However, R ₁ represents an alkyl group or alkoxyalkyl group having 1 to 10 carbon atoms, n is 2 or 4, and when n = 2
1.0≦x≦1.8, 2.5≦x≦3.5 when n=4) and a chlorine-containing tin alkoxide with the general formula Sb
(OR ₂ ) _y Cl _ny (However, R ₂ represents an alkyl group or an alkoxyalkyl group having 1 to 10 carbon atoms, m is 3 or 5, and when m = 3, 1.5≦y≦2.8,
When m = 5, the chlorine-containing antimony alkoxide shown by 2.0≦y≦4.8) is
A composition for a transparent conductive film mixed at a ratio of 20/80≧Sb/Sn≧1/99 is applied to a substrate and heated at room temperature to 300℃.
A method for forming a transparent conductive film, which comprises drying at 500 to 650°C.