JP804H - Method of forming conductive coating - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a conductive film of fluorine-doped tin oxide (SnO ₂ (F)) having no haze, low resistance, and high infrared reflectance. . That is, the coating film according to the present invention has almost no coloring, is excellent in transparency and appearance, has a high reflectance in the infrared region, and has good conductivity, and has excellent hardness and chemical mechanical durability. Therefore, it can be widely adopted in various fields by utilizing its characteristics. That is, by coating on the surface of a normal plate glass substrate, for example, anti-fog window glass of construction, automobiles, aircraft and ships or refrigeration canisters, or heat-reflecting transparent window glass, and cover glass of a solar heat collector or oven. It can be put to practical use in various fields such as door glass and parts for electric and electronic devices such as liquid crystal electro-optical displays. [Prior Art] Conventionally, when forming a tin oxide film, it is believed that the cause of haze in the film is that the chlorine glass in the tin compound reacts with the alkali in the glass to form NaCl. As a method for forming a tin oxide coating film free from haze, for example, (C ₄ H ₉ ) ₂ Sn (CH ₃ CO
O) _{2 and} other chlorine-free tin compounds and CF ₃ COOH or the like as a doping agent (Japanese Patent Publication No. 53-25).
No. 331) is known. Further, as a method for obtaining a coating having a low resistance at a relatively low glass substrate temperature, a method using SnCl ₄ as a tin compound (A. BHARD
WAJ et al. “FLUORINE-DOPED SnO ₂
FILEMS FOR SOLAR CELL APPL
ICATION "Solar Cells. 5 (198
1-182) P. 39-49) are known. [Problems to be Solved by the Invention] In the method described in Japanese Patent Publication No. 53-25331, a tin oxide coating film free from haze can be obtained, but the coating film is formed at a glass substrate temperature of 600 ° C. or lower. When formed, it is difficult to obtain a coating having low resistance and high infrared reflectance, and when a coating is formed on a glass substrate having a high temperature of 600 ° C or higher, characteristics such as resistance value and infrared reflectance are improved. However, it is difficult to obtain a good product due to distortion, warpage, etc. of the glass, and in the method described in the above-mentioned known publication, the mixed solution to be sprayed is unstable and tin deposition etc. also likely to occur, ambient equipment due to corrosion and decomposition gas of the device itself during spraying also cause severe corrosion, f is when using conventional soda-lime glass as the substrate without undercoat such as SiO ₂ Be one's hardly becomes tightly occur products are those when the conventional flat glass substrate under Cote queuing such as SiO ₂ is an essential condition from the perspective of and appearance, to obtain a value lower for more resistance However, there is a demand for a coating having a lower resistance value, which is not satisfactory. [Means for Solving Problems] The present invention has been made by paying attention to the above problems, and is 500 to 60 without an undercoat such as SiO _2.
[(C ₄ H ₉ ) Sn is formed on the surface of the glass substrate at a high temperature of 0 ° C.
_{Cl, / (C 4 H 9} ) SnCl 3 + ( alcohol +
Water)] = 20 to 50% 3 [NH ₄ F / (C ₄ H ₉ ) Sn
Cl ₃ + (alcohol + water)] = 0.01 to 0.05,
And [H ₂ O / alcohol + H ₂ O] = 10 to 90
% Of (C ₄ H ₉ ) SnCl ₃ , water, alcohol and NH ₄ F are sprayed to form a conductive film of fluorine-doped tin oxide. Provided is a method for forming a tin oxide coating film having resistance and high infrared reflectance. In the present invention, (C ₄ H ₉ ) SnCl ₃ is SnCl ₄
Corrosion to equipment and the like during spraying is less than that, is stable even in the above mixed solution, and does not cause haze of the coating film.
Further, the resistance value of the film is lower than that of other organic tin compounds. NH ₄ F may be ammonium acid fluoride. Also, it is possible to add a small amount as compared with other fluorine compounds,
With the combination of (C ₄ H ₉ ) SnCl ₃ and NH ₄ F,
(C ₄ H ₉ ) SnCl ₃ can prevent the generation of haze in the coating film by the action of the fluorine of NH ₄ F, despite the compound having chlorine. Water and alcohol are used as solvents,
Water is added to dissolve NH ₄ F. CH ₃ OH, C ₂ H ₅ OH or the like is used as the alcohol. The mixing ratio of water and alcohol can be appropriately adjusted and used, and in the case of only water, the glass substrate is rapidly cooled at the time of spraying, glass breakage or the like is generated, and appearance is not preferable such as generation of haze. . Further, in the case of only alcohol, the solubility of NH ₄ F, the growth rate of the film, the combustion of spray vapor, etc. are not preferable. In the present invention, the temperature of the glass substrate is 500 to 6
If the temperature is 00 ° C. and is lower than 500 ° C., it is difficult to obtain a coating having low resistance and high infrared reflectance, and if it is higher than 600 ° C., the glass substrate is distorted or warped. The quantitative range of the mixed solution is as follows. 1) [(C ₄ H ₉ ) SnCl ₃ / (C ₄ H ₉ ) SnCl
₃ + (alcohol + water)] = 20-50% At below 20%, the higher the proportion of the solvent (alcohol + water), to efficient film formation is difficult in such as reduction of the temperature of the substrate, 50% Beyond (C ₄ H ₉ ) SnCl ₃
Is increased, and unevenness of the coating occurs, resulting in an inhomogeneous film. 2) [NH ₄ F / (C ₄ H ₉ ) SnCl ₃ + (alcohol + water)] = 0.01 to 0.05 That is, if less than 0.01 or more than 0.05, the low resistance gradually increases. , It becomes extremely high as the number of deviations outside the range increases. 3) [H ₂ O / alcohol + H ₂ O] = 10 to 90%, that is, if it is less than 10%, the solubility of NH ₄ F decreases,
The rate of film formation slows down, and if it exceeds 90%, the temperature of the glass substrate during spraying will suddenly drop, which may cause cracking of the glass substrate. Further, the film thickness is preferably 4000 to 10000Å. If it is less than 4000 Å, a glaring interference color is liable to occur, and if it exceeds 10,000 Å, the film thickness effect is small in terms of performance, leading to cost increase. From the viewpoint of infrared reflectance, about 5000 Å is more preferable. [Operation] By using the specified amount of (C ₄ H ₉ ) SnCl ₃ or the like by the method for forming a film of the present invention as described above, a stable solution without problems such as precipitation in the mixed solution of the present invention can be obtained. As a result, a uniform film can be formed without any trouble in spraying, corrosion of the spray device and surrounding equipment can be reduced, and a low resistance film lower than other organic tin compounds can be obtained. Is what you get. Furthermore, although it is a tin compound containing chlorine, it does not cause haze, is almost colorless, has excellent transparency, and can almost maintain an appropriate gloss and smoothness in terms of appearance. It has characteristics that it has a high reflectance and a transmittance in the visible range that is almost applicable to automobile window glass. In addition to the above, since the glass substrate is not rapidly cooled during spraying, glass breakage, etc. do not occur, the growth rate of the coating is fast, the addition amount of the fluorine compound is small, and it works effectively, and the adhesive strength is sufficient. In addition, the yield and quality are good. [Examples] Examples of the present invention will be described below. Example 1 Soda lime glass having a size of 300 mm × 300 mm and a thickness of 3 mm, which had been sufficiently degreased and washed, was used as a glass substrate, and the plate temperature was raised to 540 ° C., 560 ° C. and 590 ° C. in a heating furnace, and then 30 mm. On the surface of the glass substrate, which is transferred at a speed of 1 / sec, a solution of the following tin compound solution and fluorine compound is mixed using an automatic spray gun that atomizes and sprays a spray solution of about 3 kg / cm ² of air. 3cc /
A SnO ₂ (F) film was formed by spraying at a distance of about 30 cm between the spray gun and the plate glass in an amount of sec. The film thickness is about 600
I got 0Å. Tin compound solution (C ₄ H ₉ ) SnCl ₃ 35 wt%, C ₂ H ₅ OH35
wt%, H ₂ O 30 wt% Fluorine compound NH ₄ F / tin compound solution = 0.01, 0.02, 0.0
3, 0.04 The specific resistance of the SnO ₂ (F) film obtained by the above method was measured, and the measurement result is shown in FIG. (Example 2) The glass substrate and the spraying conditions were the same as in Example 1, and the temperature of the glass substrate was 540 ° C, 560 ° C, and 590 ° C, and the tin compound solution was unchanged (C ₄ H ₉ ) SnCl ₃ 35 wt.
%, C ₂ H ₅ OH 35 wt%, H ₂ O 30 wt%,
Only the fluorine compound was kept constant at NH ₄ F / tin compound solution = 0.03, and a film was formed at each set temperature. SnO ₂ (F)
A glass substrate having a film was manufactured. Using this as a sample, the optical characteristics were measured and shown as a spectral curve in FIG. (Comparative Example) The glass substrate and the spraying conditions were the same as in Example 1, and the temperature of the glass substrate was 540 ° C, 560 ° C, 590 ° C and 6 ° C.
About 10 ° C., it was sprayed using the following as a mixed solution. 1) (CH ₃ ) ₂ SnCl ₂ 35 wt%, C ₂ H ₅ OH
25 wt%, H ₂ O 40 wt% NH ₄ F / ((CH ₃ ) ₂ SnCl ₂ + C ₂ H ₅ OH +
_{H 2 O) = 2/100} 2) (C 4 H 9) 2 Sn (CH 3 COO) 2 35wt
%, CCl ₃ CH ₃ 35 wt%, CF ₃ COOH 30w
The specific resistance of the SnO ₂ (F) film obtained on the surface of the t% glass substrate was measured, and it is shown in FIG. [Effects of the Invention] As is clear from FIG. 1, (NH ₄ F / tin compound solution) × 100 is 1 to 4%, and the temperature of the glass substrate is higher between 540 and 590 ° C. It was found that the resistance was further lowered, and that each had a minimum value between them. Moreover, in FIG. 2, even if the same mixed solution of the present invention was sprayed to form a coating film depending on the temperature of the glass substrate, an infrared characteristic was found. It affects the reflectance in the region, and the transmittance in the visible region is about the same, but about 70% was obtained, and it could be confirmed that it can be used for window glass of automobiles. In addition,
Numerically, the specific resistance is ⁴ to 7 × 10 ⁻⁴ Ωcm, and the infrared reflectance is about 80 to 87% (at 10 μm). Further, in FIG. 3, (C ₄ in the mixed solution in the present invention is shown.
H ₉ ) SnCl ₃ and another organotin compound are shown as an example by comparison, and in Example 1 is 7 to ⁴ × 10 ⁻⁴ Ω · cm, in Comparative Examples 1 and 2, 18 to 9 × 10
^{It is -4} Ωcm, and it is clear that there is a large difference in the effect on the specific resistance. As described above, according to the present invention, a haze-free low resistance film having high infrared reflectance can be obtained without precoating of SiO ₂ or the like, and can be used as a conductive material or an infrared reflecting material, Further, it has a remarkable effect that a coating can be easily formed on a glass substrate at a relatively low temperature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of the present invention, showing the effect of (NH ₄ F / tin compound solution) × 100 and the temperature of the glass substrate on the specific resistance, and FIG. The influence of the temperature of the glass substrate on the transmittance and the reflectance in one embodiment of the invention is shown.
The figure shows the effect of using (C ₄ H ₉ ) SnCl ₃ in the present invention.

Claims (1)

1. A method for forming a fluorine-doped tin oxide film by spraying a solution containing a tin compound and a fluorine compound on a glass surface at high temperature. At a temperature of 500 to 600 ° C., and as the solution, (C ₄ H ₉ ) SnCl ₃ , water, alcohol and NH ₄
A mixture of F is used, and its quantitative range is [(C
_{4 H 9) SnCl 3 / (} C 4 H 9) SnCl 3 + ( alcohol + water)] = 20-50%, _[NH 4 F / _(C 4 H
₉ ) SnCl ₃ + (alcohol + water)] = 0.01-
0.05, and [H ₂ O / alcohol + H ₂ O] =
The method for forming a conductive coating is characterized by 10 to 90%.