JP2002161262A - Surface-treating agent, method for producing thin film, substrate having thin film and solar battery panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-treating agent which does not need a thermal baking process at a high temperature when formed into a thin film for modifying the surface of a substrate, to provide a substrate having a thin coating film comprising the surface-treating agent, and to provide a solar battery panel in which a substrate using the thin film as an anti-reflective film is a glass plate. SOLUTION: This surface-treating agent comprises (A) 0.01 to 3 wt.% (converted into silica) of a silicon alkoxide, (B) 0.02 to 1N of an acid, and (C) 0 to 8 wt.% of water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treating agent for modifying the surface of a substrate such as glass, ceramics, plastics or metal. Furthermore, the present invention relates to a substrate and a solar cell panel using the thin film as an antireflection film or a protective film.

[0002]

2. Description of the Related Art Various surface treatment techniques have been developed to form a thin film on the surface of a substrate such as glass or plastic to increase the durability of the substrate or to provide new functions. For example, an anti-reflection film is formed on the surface of a window glass for vehicles or buildings, or on the surface of lenses of glasses or cameras in order to increase light transmittance and prevent glare due to reflection.
In addition, when soda lime glass comes into contact with moisture, an alkaline component precipitates on the surface, causing burn (discoloration) and warpage. Therefore, a dense and strong silica thin film is applied to the surface as necessary.

[0003] By the way, a technique of laminating two or more thin films as an antireflection film and reducing the reflectance by utilizing the interference effect of light is known. For example, Japanese Patent Application Laid-Open Nos. 4-357134 and 4-357134. JP-A-4-357135 discloses an antireflection film having such a configuration. In addition, a technique of scattering light by providing irregularities on the surface of an antireflection film to reduce the reflectance is also known.
No. 193101 and Japanese Patent Application No. 11-352970.

[0004]

However, when laminating two or more thin films, the film thickness must be strictly controlled so as to satisfy the interference condition, and a plurality of steps are required for forming the thin film. Therefore, the manufacturing cost increases. Also, in the technology of forming the surface of the thin film itself into irregularities,
When forming a thin film, it is necessary to bake it at about 500 to 600 ° C., which similarly increases the manufacturing cost. Further, this technique cannot be used for a substrate having low heat resistance, for example, a resin substrate such as plastic.

The present invention has been made in view of such a problem. It is an object of the present invention to provide a surface treatment agent that does not require high-temperature heating and sintering when forming a thin film for modifying the surface of a substrate, and a substrate provided with a thin film made of the treatment agent. It is in. Another object of the present invention is to provide a solar cell panel using the thin film formed on a glass plate as an antireflection film.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the surface treating agent according to claim 1 comprises (A) a silicon alkoxide (in terms of silica): 0.01 to 3% by weight;
(B) acid: 0.02 to 1N and (C) water: 0 to 8% by weight.

A second aspect of the present invention is the surface treating agent according to the first aspect, wherein (A) the silicon alkoxide is tetramethoxysilane or tetraethoxysilane, and (B) the acid is hydrochloric acid. is there.

The surface treating agent according to the third aspect of the present invention is the surface treating agent according to the first or second aspect of the present invention, wherein the normality of the acid (B) is N / N.
(A) The ratio by weight of silicon alkoxide (in terms of silica) is 0.03 or more.

The surface treatment agent of the invention according to claim 4 is the one according to any one of claims 1 to 3, which contains silica fine particles.

[0010] According to a fifth aspect of the present invention, there is provided a thin film manufacturing method comprising:
The surface treatment agent according to any one of claims 1 to 4 is applied to a surface of a substrate, and dried at 150 ° C or less.

[0011] The base material of the invention according to claim 6 is the base material according to claim 1.
5. A thin film comprising the surface treatment agent according to any one of the above items 4 to 4.

In the solar cell panel according to the present invention, the base material of the present invention is a glass plate, and utilizes the glass plate.

[0013]

Embodiments of the present invention will be described below in detail. In addition, it is not limited to the following embodiment.

The surface treating agent comprises (A) silicon alkoxide: 0.01 to 3% by weight (in terms of silica), (B)
Acid: 0.02 to 1N and (C) water: 0 to 8% by weight. This (A) silicon alkoxide includes a part or all of which is hydrolyzed. Similarly, (C) water is mixed with (B) an impurity in an acid solvent, an alcohol solvent, and moisture of an atmosphere. Including things. The content of the silicon alkoxide (A) is calculated in terms of silica, ie, silicon dioxide (SiO ₂ ).

The surface treating agent causes a hydrolysis reaction represented by the following chemical formula 1 between silicon alkoxide and water using an acid as a catalyst. “R” in the formula represents an alkyl group.

Embedded image (-Si-OR) + (H ₂ O) → (-Si-OH) + (ROH)

Furthermore, the silanol group formed by this reaction
(-Si-OH) cause a dehydration condensation reaction represented by the following "chemical formula 2", and as a result, a siloxane bond (-Si-O-Si-) is formed.

Embedded image (-Si-OH) + (-Si-OH) → (-Si-O-Si-) + (H ₂ O)

The hydrolysis reaction of the above formula 1 and the dehydration condensation reaction of the above formula 2 are greatly affected by the concentrations of silicon alkoxide, acid and water in the surface treating agent. As the concentration of silicon alkoxide and water is lower, the hydrolysis reaction of Formula 1 is less likely to occur, and the dehydration condensation reaction of Formula 2 is less likely to occur in a chain. On the other hand, when the concentrations of silicon alkoxide and water are too high, chemical formulas 1 and 2
Reaction proceeds during preparation or storage of the surface treatment agent,
Many polymers of silanol groups are formed. As a result, the thin film made of this surface treatment agent has a non-uniform thickness and unevenness, and has a weak adhesive force to the substrate.
In order to give the thin film the same strength as before, it is necessary to perform high-temperature heating when forming the thin film.

(B) The acid functions as a catalyst in both the hydrolysis reaction of the chemical formula 1 and the dehydration condensation reaction of the chemical formula 2. By keeping the concentration of the acid at 0.01 to 1N, the catalytic activity can be controlled sufficiently and sufficiently.
When the concentration of the acid is less than 0.01 N, the catalytic action does not reach a practical level, so that high-temperature heating is required when forming the thin film. On the other hand, if it exceeds 1N, the reaction proceeds during the preparation or storage of the surface treatment agent, and most of the components constituting the thin film are present as a polymer of silanol groups, which causes the same problem as described above.

When the concentration of (A) silicon alkoxide is relatively high, it is preferable to keep the concentration of (B) acid high. Specifically, it is preferable to set the weight percent of the normality N / (A) of (B) to 0.03 or more.

(C) When water is present in excess of 8% by weight, the hydrolysis reaction of the chemical formula 1 tends to occur during the preparation and storage of the surface treating agent, and the silanol group polymer grows greatly. . Therefore, the problem of the thickness unevenness of the thin film is likely to occur similarly to the above. In the surface treating agent, water is an essential component involved in the chemical formula 1, but it is not necessary to intentionally add the water when preparing the surface treating agent. This is because even if water is not intentionally added, it is contained in the solvent or taken in from the atmosphere. In addition, since water is a reaction product of Chemical Formula 2, it is sufficient that water is present as needed to initiate the hydrolysis reaction of Chemical Formula 1. Therefore, the water content may be 0% by weight, meaning that it is not necessary to add intentionally in the preparation of the surface treatment agent.

(A) The type of silicon alkoxide is not particularly limited, and examples thereof include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane and tetrabutoxysilane.
Since those having a relatively small molecular weight can easily form a dense thin film, for example, tetraalkoxysilane having an alkoxyl group having 3 or less carbon atoms is preferable.

(B) The type of the acid is preferably one which volatilizes at room temperature and does not remain in the thin film when the thin film is formed on the substrate.
For example, hydrochloric acid, hydrofluoric acid, nitric acid, acetic acid, formic acid or trifluoroacetic acid can be mentioned. Among them, hydrochloric acid, which has high volatility and is relatively easy to handle, is preferred.

The solvent of the surface treatment agent is not particularly limited, but an alcohol solvent which does not require heating in forming a thin film is preferable. Examples include methanol, ethanol, 1-propanol, 2-propanol, butyl alcohol or amyl alcohol. Among them, chain-type saturated monohydric alcohols having 3 or less carbon atoms, such as methanol, ethanol, 1-propanol and 2-propanol, are suitable in terms of the evaporation rate at room temperature.

In the preparation of the surface treating agent, (A) silicon alkoxide, (B) acid and alcohol are mixed and stirred to hydrolyze the silicon alkoxide. Next, a method of preparing a solution by further adding a silicon alkoxide, an acid and an alcohol to the solution is preferable.

The method for applying the surface treating agent to the substrate is not particularly limited, and examples thereof include dip coating,
Known methods such as flow coating, spin coating, bar coating, roll coating, spray coating, hand coating and brush coating are used.

In the surface treatment agent applied to the substrate, the alcohol component evaporates rapidly due to the increase in the specific surface area, and (A)
The concentration of silicon alkoxide and its hydrolyzate increases. Therefore, the suppressed hydrolysis reaction of the chemical formula 1 and the dehydration condensation reaction of the chemical formula 2 suddenly progress through the weir, and the siloxane bond (—Si—O—Si—) is uniformly formed without bias. As a result, the surface of the substrate is covered with a uniform, dense, high-physical-chemical strength silica thin film. And since this siloxane bond is completed with the evaporation of the solvent, the subsequent baking is essentially unnecessary. However,
(C) When the content of water is high or the thickness of the thin film is relatively thick, a non-volatile solvent or an organic impurity is contained in the surface treatment agent in order to increase the forming speed of the thin film. In such a case, in order to remove these, heating and firing may be performed within a range that does not affect the physical properties of the base material. For example, 15
By heating to about 0 ° C., most organic impurities can be vaporized. Further, when the temperature is about 150 ° C., it is only necessary to heat the surface to which the surface treating agent is applied with a dryer, so that the present invention can be applied to a substrate having low heat resistance.

The thin film formed using this surface treating agent (hereinafter, simply referred to as “silica thin film”) contains silica as a main component and is used as a surface protective film or a modified film of various base materials. It is possible. For example, this silica thin film has a refractive index of 1.4 to 1.5, and can function as an antireflection film if a substrate is appropriately selected.

When this silica thin film is used as an antireflection film, it is preferable to provide unevenness on its surface to reduce the reflectance due to light scattering. The method for forming the surface irregularities is not particularly limited, but it is preferable that the method does not decrease the strength of the silica thin film and further reduces the refractive index thereof. Specifically, in the preparation of the surface treatment agent, a method in which silica fine particles are mixed in advance is exemplified. That is, in the preparation of the surface treatment agent, (A)
When silicon alkoxide, (B) acid and alcohol are mixed and stirred to hydrolyze silicon alkoxide, silica microparticles are added to produce a co-hydrolysis solution. Then, a silicon alkoxide,
A method prepared by adding an acid and an alcohol is preferred.
It has been confirmed by the experiments of the present inventors that the physical strength of the thin film is significantly improved by adjusting the surface treatment agent in two stages as described above. The “co-hydrolysis solution” refers to a solution in which both silica fine particles and silicon alkoxide are hydrolyzed in the presence of both.
According to this method, irregularities can be formed on the surface of the silica thin film in the same manner as in the formation of the silica thin film.

When the silica fine particles are incorporated into the silica thin film by the above method, since the silica fine particles have a silanol group, a siloxane bond is formed with the silicon alkoxide (A) in the surface treating agent. Therefore, the silica fine particles are firmly fixed in the silica thin film.

As the silica fine particles, for example, silica fine particles synthesized by reacting silicon alkoxide in the presence of a basic catalyst such as ammonia by a sol-gel method, colloidal silica using sodium silicate or the like, or synthesized in the gas phase. Fumed silica. However, the silica fine particles may contain a trace component other than silica.

The silica fine particles may be completely buried in the silica thin film, or may be in a state in which a part thereof is protruded from the thin film. However, in order to reduce the refractive index of the silica thin film, it is preferable that a part of the silica fine particles protrude from the silica thin film. In this state, gaps are formed between the silica fine particles, and the gaps reduce the apparent refractive index of the silica thin film, and the antireflection effect is further enhanced. In addition, if at least 1/4 of the particle diameter of the silica fine particles is buried in the silica thin film, the silica fine particles will not fall off carelessly. In this state, the abrasion resistance of the silica thin film is improved. This is because the friction body first comes into contact with the protruding silica fine particles, so that even when a large frictional force is applied, only the silica fine particles are peeled off, and the silica thin film can still remain. For example, we have:
A silica thin film in which the silica fine particles protruded by half of the particle size was formed on a glass plate, and a wear resistance test was performed in which the silica thin film was rubbed with a wiper blade for 10 days. It almost remained. It should be noted that a similar function is exhibited even when magnesium fluoride is used instead of the silica fine particles.

Further, by forming pores inside the silica thin film, the apparent refractive index can be reduced. However, if the porosity is too high, the physical and chemical strength of the silica thin film is reduced. Therefore, the porosity is preferably 20% by volume or less, more preferably 10% by volume or less. The method for forming the internal pores is not particularly limited, and the following methods can be exemplified. That is, fine particles having physical or chemical properties different from those of the silica thin film are previously blended in the surface treatment agent, and the silica thin film is formed by the above-described method of forming a silica thin film. Then, fine particles having different properties existing in the silica thin film are eluted by heating or vaporizing or using a chemical.

When pores are formed inside the silica thin film, fine silica particles may be used as described above.
In this case, the reflectance of the silica thin film may change significantly with time depending on the particle size of the silica fine particles. For example,
When the particle size of the silica fine particles is small, the gap between the particles becomes small, so that the capillary force increases and it becomes difficult to remove dirt. Also,
Moisture and organic matter in the air gradually accumulate in these small gaps, and the refractive index of the silica thin film gradually increases. Such a performance deterioration phenomenon with time is more likely to occur as the particle size of the silica fine particles is smaller. According to the knowledge obtained from many experiments of the present inventors, in order to prevent the performance degradation over time,
The average particle size of the silica fine particles is 10 nm or more,
nm or more is preferred. On the other hand, if the particle size of the silica fine particles is too large, the adhesion between the substrate and the silica thin film decreases.
Therefore, the average particle size of the silica fine particles is preferably 1,000 nm or less.

When pores are provided inside the silica thin film and silica fine particles are blended, the content of the silica fine particles in the silica thin film (including the silica fine particles) is preferably 50 to 85% by weight. If the amount of the silica fine particles is too small, the silica fine particles are completely buried and covered, making it difficult to form irregularities on the surface of the silica thin film. In addition, there is no gap between the silica fine particles, and the apparent decrease in the refractive index based on this gap does not occur. On the other hand, if the amount of the silica fine particles is too large, the integrity of the silica thin film is impaired.

Incidentally, a coating made of an organosilane having a hydrolyzable group or a functional functional group or a hydrolyzate thereof (including a partial hydrolyzate) may be formed on the silica thin film. By forming the overcoat film, functions such as water repellency, oil repellency, antifogging, antifouling, low friction resistance, and antireflection can be imparted to the silica thin film.

The type of the substrate is not particularly limited, and any substrate requiring an antireflection film or a surface protective film can be used. For example, glass, ceramics, metal or plastics.

When this surface treatment agent is used, high-temperature heating is not required for forming the silica thin film, and therefore, it can also be used for plastics having low heat resistance, in which the silica thin film could not be easily formed conventionally. Further, if this silica thin film is formed on a glass plate, the glass plate and the silica thin film are siloxane-bonded, so that the adhesion strength of the silica thin film becomes extremely high.

Since the substrate provided with the silica thin film is provided with an antireflection film or a surface protection film, it can be effectively used in various applications requiring its function. In recent years, solar cells have been actively manufactured due to the emergence of energy problems, and a glass plate having this silica thin film can be used for a solar cell panel. When used for a solar cell panel, the silica thin film functions as an anti-reflection film, and can guide more sunlight to the photoelectric conversion layer. In addition, when the silica thin film has irregularities, a so-called light confinement effect by light scattering can be obtained.

[0039]

The present invention will be described more specifically with reference to the following examples. (Example 1) Ethanol (manufactured by Nakarai Test) 37.1
5.2 g of tetraethoxysilane (manufactured by Kanto Chemical) to 3 g,
1 g of concentrated hydrochloric acid (35% by weight, manufactured by Kanto Chemical) and an aqueous dispersion containing silica fine particles (fine particles 15% by weight, fine particle diameter 110
nm spherical particles Nippon Shokubai's Sea Hostar KE-W10)
56.67 g were mixed and stirred at room temperature for 24 hours to prepare a co-hydrolyzed solution. Then, 3 g of this co-hydrolyzed solution, 94 g of ethanol (manufactured by Nakarai Test) and concentrated hydrochloric acid (3
3% by weight (7% by weight, manufactured by Kanto Chemical Co., Ltd.) to prepare a surface treating agent. For this surface treatment agent, the concentration of tetraethoxysilane (in terms of silica), the concentration of hydrochloric acid and water, the normality N of hydrochloric acid divided by the weight% of tetraethoxysilane (in terms of silica), and the content of fine silica particles in the silica thin film (Weight ratio of silica fine particles / tetraethoxysilane (in terms of silica)) is shown in Table 1 below. On a washed soda-lime silicate glass plate (150 × 150 mm), the above surface treatment agent is applied by flow coating at room temperature and humidity of 30% at room temperature, and dried at room temperature to form a silica thin film containing silica fine particles. Molded. Regarding this silica thin film, first, the reflectance (average value of the light wavelength of 400 to 800 nm) is determined according to JIS R3.
The measurement was performed by the method of No. 106, and the film strength was evaluated by a Taber abrasion test. The results are shown in Table 1 below. The Taber abrasion test was performed according to JIS-
According to R3221, a CS-10F rotating wheel was used to evaluate the presence or absence of a silica thin film after 50 rotations at 2.5 N.場合 indicates that the silica thin film remained, and X indicates that the remaining silica thin film could not be confirmed.

Example 2 In Example 1, a surface treating agent was prepared by mixing 5 g of the co-hydrolyzed solution, 94.4 g of ethanol, 0.1 g of tetraethoxysilane and 0.5 g of concentrated hydrochloric acid. In the same manner as in Example 1, a silica thin film containing silica fine particles was formed and evaluated. The results are shown in Table 1 below.

Example 3 The same procedure as in Example 1 was carried out, except that Snowtech OUP (chain particles having a particle size of 15% by weight and an average particle size of 30 nm) manufactured by Nissan Chemical Co., Ltd. was used in the aqueous dispersion containing silica fine particles. A co-hydrolysis solution was prepared. And
5 g of this co-hydrolysis solution, 93.5 g of ethanol, 0.5 g of tetraethoxysilane and 1 g of concentrated hydrochloric acid were mixed to produce a surface treating agent, and otherwise the same as in Example 1,
A silica thin film containing silica fine particles was formed and evaluated. The results are shown in Table 1 below.

(Comparative Example 1) Co-hydrolysis solution 10 of Example 3
g, ethanol 84.8 g, tetraethoxysilane 0.
2 g and 10 g of concentrated hydrochloric acid were mixed to produce a surface treating agent, and otherwise the procedure of Example 1 was followed to form and evaluate a silica thin film containing fine silica particles. The result is
It is also described in “Table 1” below.

Comparative Example 2 Co-Hydrolyzed Solution 5 of Example 1
g, ethanol 94.4 g, tetraethoxysilane 0.
5 g and 0.05 g of concentrated hydrochloric acid were mixed to produce a surface treatment agent, and the other conditions were the same as in Example 1 to form and evaluate a silica thin film containing silica fine particles. The results are shown in Table 1 below.

(Comparative Example 3) Co-hydrolysis liquid 5 of Example 3
g, 94.9 g of ethanol and 0.2 g of tetraethoxysilane were mixed to produce a surface treating agent. Except for the above, a silica thin film containing fine silica particles was formed and evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

Comparative Example 4 3 g of the co-hydrolyzed solution of Example 1
Then, 97 g of ethanol was mixed to produce a surface treating agent, and otherwise the procedure of Example 1 was followed to mold and evaluate a silica thin film containing fine silica particles. The result is
It is also described in “Table 1” below.

Comparative Example 5 The glass plate provided with the silica thin film manufactured in Comparative Example 4 was placed in an electric furnace at a set temperature of 500 ° C. for 1 hour.
Bake for 5 minutes. This glass plate was subjected to measurement of refractive index and Taber abrasion test. The results are shown in Table 1 below.

Comparative Example 6 A co-hydrolyzed solution was prepared in the same manner as in Example 1 except that ethyl cellosolve (manufactured by Nakarai Test) was used instead of ethanol. 30 g of this co-hydrolysis solution, 40 g of hexylene glycol (manufactured by Nakarai Test) and 30 g of ethyl cellosolve were mixed to produce a surface treating agent. 1,200 r.
The coating was applied on the glass plate of Example 1 by a spin coater at pm and baked for 15 minutes in an electric furnace at a set temperature of 500 ° C. to form a silica thin film containing silica fine particles. The refractive index of this silica thin film was measured in the same manner as in Example 1, and a Taber abrasion test was performed. The results are shown in Table 1 below.

(Comparative Example 7) A surface treating agent was prepared by mixing 1 g of the co-hydrolysis solution, 87.5 g of ethanol, 0.5 g of tetraethoxysilane and 11 g of concentrated hydrochloric acid in Example 1. In the same manner as in Example 1, a silica thin film containing silica fine particles was formed and evaluated. The results are shown in Table 1 below.

[0049]

[Table 1] ==================================== (A) (B) (C) Tetra Ethoxy silane Hydrochloric acid aqueous solution (B) / (A) Fine particles after coating Film strength Reflection (in terms of silica) Treatment rate (wt%) (N) (wt%) (%) (%) −−−−−−−−−− −−−−−−−−−−−−−−−−−−−−−−−−−−−− Example 1 0.30 0.307 3.4 1.024 85 Air drying at room temperature ○ 5.2 Example 2 0.53 0.056 2.8 0.105 80 Air drying at room temperature ○ 5.4 Example 3 0.76 0.106 3.1 0.165 66 Air-dry at room temperature ○ 5.0 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Comparison Example 1 1.06 0.975 11.2 0.922 80 Room temperature air drying × 5.3 Comparative example 2 0.64 0.010 2.5 0.016 66 Room temperature air drying × 5.9 Comparative example 3 0.53 0.005 2.4 0.010 80 Room temperature air drying × 4.9 Comparative example 4 0.30 0.003 1.5 0.010 85 Room temperature air drying × 5.2 Comparative example 5 0.30 0.003 1.5 0.010 85 500 ° C baking ○ 5.2 Comparative Example 6 3.00 0.030 14.6 0.010 85 500 ° C baking ○ 5.3 Comparative example 7 0.24 1.116 7.4 4.570 35 Room temperature air drying × 6.8 ===================================== ===

The following can be understood from the comparison between the above-described example and the comparative example. By comparing Examples 1 to 3 with Comparative Examples 1 and 6, when the concentration of water (C) as the surface treatment agent is high, the hydrolysis reaction of the above chemical formula 1 proceeds during its preparation and storage, and room temperature It turns out that the strength of the silica thin film is insufficient in the molding.

By comparing Examples 1 to 3 with Comparative Examples 2 to 4, it can be seen that when the concentration of the acid (B) in the surface treating agent is low, the strength of the silica thin film is insufficient. Comparative Example 5
In consideration of the fact that the silica thin film heated and baked at a high temperature has sufficient strength, when the concentration of (B) the acid is low, the hydrolysis reaction of the above chemical formula 1 and the dehydration condensation reaction of the above chemical formula 2 are sufficient. It turns out that it does not progress.

On the other hand, by comparing Examples 1 to 3 with Comparative Example 7, it can be seen that the strength of the silica thin film is insufficient even when the concentration of the acid (B) in the surface treating agent is high.

[0053]

According to the present invention having the above configuration, the following effects are obtained. According to the first aspect of the present invention, since the content of the component of the surface treating agent is appropriate, it is possible to obtain a silica thin film having extremely high adhesive force to a substrate without requiring high-temperature heating.

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention described above, a silica thin film in which no impurities remain even without heating at a high temperature can be obtained.

According to the third aspect of the present invention, the first aspect is provided.
In addition to the effects of the second aspect of the invention, in the surface treatment agent, a sufficient amount of the catalyst for the reaction raw material is present, so that a silica thin film is quickly formed.

According to the fourth aspect of the present invention, the first aspect is provided.
(3) In addition to the effects of the invention of any one of (1) to (3), surface irregularities are formed by the silica fine particles, so that a silica thin film having a lower refractive index can be obtained.

According to the fifth aspect of the present invention, the first aspect is provided.
Since the surface treatment agent according to any one of the above items 1 to 4, the silica thin film can be formed without performing high-temperature heating.

According to the invention of claim 6, according to claim 1,
Since the surface treatment agent according to any one of the above items 1 to 4, is used, a silica thin film can be formed even on a substrate having low heat resistance.

According to the seventh aspect of the present invention, since the solar cell panel has a silica thin film formed on a glass plate, a reduction in reflectance due to light scattering and an effect of confining light are exhibited, and the photoelectric conversion layer is used. Can guide a lot of sunlight.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 183/04 C09D 183/04 G02B 1/11 G02B 1/10 A H01L 31/04 H01L 31/04 F ( 72) Inventor Toshifumi Tsujino 3-5-11, Doshu-cho, Chuo-ku, Osaka-shi, Japan Inside Nippon Sheet Glass Co., Ltd. F term (reference) 2K009 AA02 AA12 CC09 CC42 DD02 4F100 AA01A AA40A AB11A AG00B AH06A AT00B BA02 CA30A DE01A EJ64A GB90 JM02A JN06 4G059 AA01 AC04 AC16 EA05 EB07 4J038 DL021 HA031

Claims (7)

[Claims] 1. A surface treating agent containing (A) silicon alkoxide (calculated as silica): 0.01 to 3% by weight, (B) acid: 0.02 to 1N, and (C) water: 0 to 8% by weight. . 2. The surface treating agent according to claim 1, wherein (A) the silicon alkoxide is tetramethoxysilane or tetraethoxysilane, and (B) the acid is hydrochloric acid. 3. The ratio of (B) the normality of acid (N) / (A) wt% of silicon alkoxide (in terms of silica) is 0.
The surface treating agent according to claim 1, wherein the surface treating agent is 03 or more. 4. The surface treating agent according to claim 1, which contains silica fine particles. 5. A method for producing a thin film, comprising applying the surface treating agent according to any one of claims 1 to 4 to a surface of a substrate, and drying the applied surface treatment agent at 150 ° C. or lower. 6. A substrate provided with a thin film comprising the surface treatment agent according to claim 1. Description: 7. A solar cell panel using the base material according to claim 6, wherein the base material is a glass plate.