JPH09328336A - Coating film having photocatalyst activity and composition forming the same coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition capable of forming a coating film excellent in photocatalyst activity, mechanical strength and chemical resistance only by directly applying to a substrate without requiring specific pretreatment by using a specific composition. SOLUTION: This composition contains (A) TiO2 fine particles having <100nm average particle diameter, (B) a Zr element-containing compound and (C) a Si element-containing compound, and a weight ratio of the components B and C to the component A expressed in terms of a weight ratio of the component A: (the component B expressed in terms of ZrO2 ):(the component C expressed in terms of SiO2 is 1:(0.02 to 0.5):(0.2-2.5). A tetraalkoxide, an acetylacetoxylate compound, an alkoxyacetylacetone chelate compound or an acetate compound of Zr is exemplified as the component B. An alkoxysilane compound, chlorosilane compound, an isocyanato silane compound or these hydrolyzate is exemplified as the component C. This coating film is obtained by directly applying the composition to a substrate and heat-treating the composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention imparts stain decomposability, antifogging property, deodorizing property, mold resistance and antibacterial property to various substrates such as glass, plastic, metal, ceramics, etc. The present invention relates to a photocatalytically active coating capable of effectively utilizing energy of a lamp or the like, and a composition for forming the coating.

[0002]

2. Description of the Related Art With the emergence of environmental problems and the like, deodorizing properties in the indoor space and indoor and outdoor glass, outer wall materials,
Building materials such as tiles are required to have antifouling properties, antifungal properties, antibacterial properties, antifog properties, and the like. Moreover, similar characteristics are required not only for building materials but also for constituent materials such as home electric appliances, office supplies and various vehicles.

As a conventional technique for such a requirement, T is
The semiconductor photocatalyst substance represented by iO _2, spraying,
It has been proposed to form it on the surface of the substrate by a conventionally known method such as a spin method, a dip method, a sputtering method, etc.
-278241).

However, since the coating formed by the conventional technique has insufficient catalytic activity, mechanical strength and chemical resistance, the catalytic activity is lowered or scratched during use, and from a practical point of view. I wasn't satisfied.

Further, the conventionally proposed coating has a large refractive index, so that when the coating is formed on a transparent material such as glass, strong interference fringes are generated, leaving a problem in design. Furthermore, conventional proposals have been made to enhance photocatalytic activity.
An intermediate layer such as a SiO ₂ film is provided between the base material and the photocatalyst layer, which is disadvantageous from the viewpoint of cost and the like.

[0006]

The present invention does not require a special pretreatment such as providing an intermediate layer, and a film having excellent photocatalytic activity, mechanical strength and chemical resistance can be obtained by directly applying it to a substrate. A film-forming composition having photocatalytic activity that can be formed;
An object of the present invention is to provide a film having photocatalytic activity formed by using the composition, a method for producing the film, and a substrate having the film.

[0007]

The present invention provides (1) TiO ₂ fine particles having an average particle size of less than 100 nm (hereinafter, also referred to as compound (1)) and (2) a Zr element-containing compound (hereinafter, compound ( (2)) and (3) Si element-containing compound (hereinafter, also referred to as compound (3)), and (1)
The weight ratio of (2) and (3) to (1) :( ZrO
₂ conversion (2)): (SiO ₂ conversion (3)) = 1:
A composition is provided that is 0.02-0.5: 0.2-2.5.

The compound (1) used in the present invention is an essential component for expressing the catalytic activity, and has an average particle diameter of 100 nm.
Is less than fine particles. The shape of the TiO ₂ fine particles is not particularly limited, but spherical and acicular shapes are preferable because they can improve the denseness of the film and increase the mechanical strength.

Further, if the average particle size of the fine particles is 100 nm or more, good physical properties cannot be obtained in terms of film appearance (particularly transparency) and mechanical strength. Further, from the viewpoint of catalytic activity, TiO 2
The crystal form of ₂ is preferably anatase type.

One of the characteristics of the present invention is that a material which has been made into fine particles is used as a TiO ₂ source. This product has a catalytic activity and mechanical strength higher than that of a TiO ₂ film obtained by thermally decomposing various titanium compounds (for example, various titanium chelate compounds such as titanium alkoxide, titanium acetylacetone compound and titanium octylene glycol compound). Good balance. The reason is presumed as follows.

The membrane using TiO ₂ fine particles has a mechanical structure secured by the chain structure of the fine particles, and the gaps between the fine particles contribute to the formation of pores. As a result, the surface area of the membrane is increased and the catalytic activity is high. It is considered to be. On the other hand, a film obtained by thermally decomposing various titanium compounds has many volatilized parts by being thermally decomposed, so that the chain structure of the titanium compound is difficult to be taken, and the denseness of the film is exerted. It is considered to be difficult to develop.

The compounds (2) and (3) used in the present invention are essential components for dramatically improving the durability of the film, that is, the mechanical strength and chemical resistance. Compound (2), (3)
Are compounds containing Zr element and Si element, respectively, which can be ZrO ₂ and SiO ₂ components in the heat treatment step.

Examples of the compound (2) include zirconium tetraalkoxide, zirconium acetylacetone chelate compound, zirconium alkoxyacetylacetone chelate compound and zirconium acetate compound.

Specifically, Zr (acac) ₄ , Zr
(OR) ₄ , Zr (acac) (OR) ₃ , Zr (ac
ac) ₂ (OR) ₂ , Zr (acac) ₃ (OR), Z
Examples thereof include rO (OC ₂ H ₃ O ₂ ) ₂ . Where ac
ac is C ₅ H ₇ O ₂ acetylacetone, OR is OC
_It means an alkoxy group such as ₃ H ₇ or OC ₄ H ₉ .

Examples of the compound (3) include alkoxysilane compounds, chlorosilane compounds, isocyanate silane compounds, and partial hydrolysis products thereof.

Specifically, Si (OR) ₄ , R ¹ Si
(OR) ₃ , R ¹ R ² Si (OR) ₂ , Si (NCO) ₄
, R ¹ Si (NCO) ₃ , R ¹ R ² Si (NCO)
₂ , ethyl silicate 40 (a partial hydrolysis product of tetraethoxysilane and having an average degree of polymerization of 5)
Etc., and their partial hydrolysis products and the like.
Here, R ¹ and R ² mean an alkyl group.

The compounds (2) and (3) are not limited to one kind of material, and may be a mixture of two or more kinds of compounds or a cohydrolysis product.

The weight ratio of compound (2) to compound (1) [(weight of compound (2) in terms of ZrO ₂ ) / (1)] is 0.02 to 0.5. This is because if it is less than 0.02, the effect of addition, mechanical strength and chemical resistance are not expressed, and if it is more than 0.5, the photocatalytic activity and the adhesion of the coating to the substrate are deteriorated.

A weight ratio of the compound (3) to the compound (1) [(weight of the compound (3) in terms of SiO ₂ ) / (1)] is 0.2 to 2.5. This is because if it is less than 0.2, the effect of addition is not exhibited, the mechanical strength and chemical resistance are not improved, and if it is more than 2.5, the photocatalytic activity is lowered.

Further, if the compounds (2) and (3) are used alone, their mechanical strength and chemical resistance are improved to some extent.
The effects as seen when the compounds (2) and (3) coexist as in the present invention cannot be expected.

The weight ratio of the compound (2) to the compound (3) is not particularly limited, but (the ZrO ₂ equivalent weight of the compound (2)) / (the SiO ₂ equivalent weight of the compound (3)) is 0.
It is desirable that it is 05 to 0.7. If it is less than 0.05, the synergistic effect of the compound (2) and the compound (3) is difficult to obtain, and if it exceeds 0.7, the adverse effect of the compound (2) begins to appear, that is, the adhesion of the film to the substrate is This is because it will decrease.

As the method for applying the composition of the present invention, spray coating, spin coating, flexographic printing, screen printing, dip coating, brush coating, flow coating and the like can be used.

By using the composition of the present invention, it is not necessary to provide an intermediate layer such as a SiO ₂ film between the coating film and the substrate as in the prior art, and the composition can be directly applied to the substrate and heat treated. A film having excellent photocatalytic activity, mechanical strength and chemical resistance is obtained. That is, it is considered that the method is advantageous in terms of cost without requiring special pretreatment. However, there is no problem in performing pretreatment for any purpose.

The heat treatment condition in the present invention is that the temperature is 80.
The temperature profile can be set appropriately depending on the purpose. The present invention is characterized in that the characteristics can be exhibited even at low temperature treatment as described above.

The thickness of the coating is preferably set to 30 to 300 nm. This is because if it is less than 30 nm, it is difficult to obtain sufficient photocatalytic activity, and if it exceeds 300 nm, mechanical strength is lowered, so that scratches and the like become conspicuous and practical characteristics are lowered.

The substrate in the present invention is not particularly limited, and glass, ceramics, plastics, metals and their composites and laminates can be used. The surface of the substrate is made of a material different from that of the substrate itself such as a surface of the substrate itself or a surface-treated surface (for example, a glass surface provided with a sol-gel film, a sputter film, a CVD film, a vapor deposition film, etc.). It may be the surface. The shape of the base material is not particularly limited, and may be a planar shape, or an arbitrary shape depending on the purpose, such as a shape having a curvature on the whole surface or a part thereof.

[0027]

EXAMPLES The evaluation methods used in Examples and Comparative Examples are as follows.

Photocatalytic activity: The rate of photodecomposition of acetaldehyde, which is a malodorous component of tobacco, was evaluated. 50 experiments
Put the mm square sample in a 3 liter quartz square reaction tube,
Introduce acetaldehyde vapor into the reaction tube, irradiate the sample with black light from the outside of the quartz reaction tube so that the UV intensity on the surface of the sample becomes 1.5 mW / cm ^2, and measure the decrease in acetaldehyde with a gas chromatograph. The rate of acetaldehyde decomposition was determined. The decomposition rate was expressed by the amount of weight loss per unit time and unit area [μg / (h · cm ² )].

Abrasion resistance: load of 500 on Taber tester
g, abrasion 1000 times, and the amount of change in haze before and after the test was determined.

Appearance quality: The appearance of the obtained test piece was visually checked for the presence of interference fringes.

Anti-fogging property: Initial anti-fog property and durable anti-fog property were classified and evaluated by the following methods. The initial anti-fog property was visually observed by blowing a breath on the sample to see if fogging occurred. The durable anti-fog property is
The obtained test piece was immersed in warm water at 60 ° C. for 3 days and then evaluated in the same manner as the initial antifogging property. In the evaluation of the antifogging property, ∘ indicates that no fogging occurred, and x indicates that fogging occurred.

Chemical resistance: 2 in 0.1N NaOH aqueous solution
After soaking for 4 hours, changes in the appearance of the film were visually observed.

Example 1 In 56 g of an ethanol dispersion solution of titanium oxide fine particles (10% by weight of anatase TiO ₂ fine particles, average particle diameter 60 nm), 478 g of ethanol, 12.5 g of tetramethoxysilane and zirconium tributoxyacetylacetonate Zr ( C ₅ H ₇ O ₃ ) (O
2.3 g of Bu) ₃ were added. The above solution was stirred at 25 ° C. for 1 hour to obtain treating agent 1. In this case, the SiO ₂ equivalent weight / TiO ₂ equivalent weight = 0.87, and the ZrO ₂ equivalent weight / TiO ₂ equivalent weight = 0.09.

1 cc of the treating agent 1 was dropped on a glass substrate which had been washed in advance, spin coating was performed, and then 650
A heat treatment was performed at 5 ° C for 5 minutes to obtain a test piece. The film thickness of the coating provided on this test piece was 86 nm. The evaluation results of this test piece are shown in Table 1 (hereinafter the same).

[Example 2] 12.5 g in Example 1
A test piece was prepared and evaluated in the same manner as in Example 1 except that 12.0 g of ethyl silicate 40 was used in place of tetramethoxysilane in Example 1.

Example 3 Average particle size of Example 1 60 n
A test piece was prepared and evaluated in the same manner as in Example 1 except that the titanium oxide fine particles of m had an average particle diameter of 33 nm.

Example 4 In 56 g of an ethanol dispersion solution of titanium oxide fine particles (10% by weight of anatase TiO ₂ fine particles, average particle diameter 60 nm) was added 330 g of ethanol, 4.3 g of tetramethoxysilane and Zr (C ₅ H ₇ O _3). )
2.5 g of (OBu) ₃ was added. The above solution was stirred at 25 ° C. for 1 hour to obtain treating agent 4. In this case, the weight calculated as SiO ₂ / the weight calculated as TiO ₂ = 0.29, and the weight calculated as ZrO ₂ / the weight calculated as TiO ₂ = 0.10.

1 cc of the treating agent 4 was dropped on a glass substrate which had been washed in advance, spin coating was performed, and then 650
A heat treatment was performed at 5 ° C for 5 minutes to obtain a test piece. The film thickness of the coating provided on this test piece was 86 nm.

Example 5 In 56 g of an ethanol dispersion solution of titanium oxide fine particles (10% by weight of anatase TiO ₂ fine particles, average particle diameter 60 nm), 395 g of ethanol, 6.5 g of tetramethoxysilane and Zr (C ₅ H ₇ O ₃ )
5.0 g of (OBu) ₃ was added. The above solution was stirred at 25 ° C. for 1 hour to obtain treating agent 5. In this case, the weight calculated as SiO ₂ / the weight calculated as TiO ₂ = 0.45, and the weight calculated as ZrO ₂ / the weight calculated as TiO ₂ = 0.20.

1 cc of the treating agent 5 was dropped on a glass substrate which had been washed in advance, spin coating was performed, and then 650
A heat treatment was performed at 5 ° C for 5 minutes to obtain a test piece. The film thickness of the coating provided on this test piece was 86 nm.

Example 6 Instead of 5.0 g of Zr (C ₅ H ₇ O ₃ ) (OBu) ₃ in Example 5, 5.96 was used.
Test pieces were prepared and evaluated in the same manner as in Example 5 except that g of zirconium tetraacetylacetonate was used.

[Comparative Example 1] To 56 g of an ethanol dispersion solution of titanium oxide fine particles (10% by weight of anatase TiO ₂ fine particles, average particle diameter 60 nm), 455 g of ethanol and 12.5 g of tetramethoxysilane were added. The above solution was stirred at 25 ° C. for 1 hour to obtain a treating agent R1.

1 cc of the treating agent R1 was dropped on a glass substrate which had been washed in advance, spin coating was performed, and then 65
A heat treatment was performed at 0 ° C. for 5 minutes to obtain a test piece. The film thickness of the coating provided on this test piece was 83 nm.

[Comparative Example 2] 56 g of an ethanol dispersion solution of titanium oxide fine particles (10% by weight of anatase TiO ₂ fine particles having an average particle diameter of 60 nm) was mixed with 446 g of ethanol and Z.
22.0 g of r (C ₅ H ₇ O ₃ ) (OBu) ₃ was added. The above solution was stirred at 25 ° C. for 1 hour to obtain a treating agent R2.

1 cc of the treating agent R2 was dropped on a glass substrate which had been washed in advance, spin coating was performed, and then 65
A heat treatment was performed at 0 ° C. for 5 minutes to obtain a test piece. The film thickness of the coating provided on this test piece was 86 nm.

[Comparative Example 3] 224 g of ethanol was added to 56 g of an ethanol dispersion solution of titanium oxide fine particles (10% by weight of anatase TiO ₂ fine particles, average particle diameter 60 nm). The above solution was stirred at 25 ° C. for 1 hour to obtain a treating agent R3.

1 cc of the treating agent R3 was dropped on a glass substrate which had been washed in advance, spin coating was performed, and then 65
A heat treatment was performed at 0 ° C. for 5 minutes to obtain a test piece. The film thickness of the coating provided on this test piece was 92 nm.

Comparative Example 4 56 g of an ethanol dispersion solution of titanium oxide fine particles (10% by weight of anatase TiO ₂ fine particles having an average particle diameter of 60 nm) was added to 478 g of ethanol, 1.43 g of tetramethoxysilane and Zr (C ₅ H ₇ O).
₃ ) 0.3 g of (OBu) ₃ was added. 25 above solution
It stirred at 1 degreeC for 1 hour, and obtained the processing agent R4. In this case, SiO
₂ converted weight / TiO ₂ converted weight = 0.10, and Zr
O ₂ equivalent weight / TiO ₂ equivalent weight = 0.01.

1 cc of the treating agent R4 was dropped onto a glass substrate which had been washed in advance, spin coating was performed, and then 65
A heat treatment was performed at 0 ° C. for 5 minutes to obtain a test piece. The film thickness of the coating provided on this test piece was 85 nm.

[Comparative Example 5] Ethanol 638 g, tetramethoxysilane 21.6 g and Zr (C ₅ H ₇ O) were added to 28 g of an ethanol dispersion solution of titanium oxide fine particles (10% by weight of anatase TiO ₂ fine particles having an average particle diameter of 60 nm).
₃ ) 12.6 g of (OBu) ₃ was added. 2 above solution
It stirred at 5 degreeC for 1 hour, and obtained the processing agent R5. In this case Si
O ₂ equivalent weight / TiO ₂ equivalent weight = 3.01 and Z
rO ₂ converted weight / TiO ₂ converted weight = 1.00.

1 cc of the treating agent R5 was dropped on a glass substrate which had been washed in advance, and spin coating was performed.
A heat treatment was performed at 0 ° C. for 5 minutes to obtain a test piece. The film thickness of the coating provided on this test piece was 78 nm.

Comparative Example 6 Tetrabutoxytitanium 23.
8g, ethanol 478g, tetramethoxysilane 1
2.5 g and Zr (C ₅ H ₇ O ₃ ) (OBu) ₃ 2.3
g was added. The above solution was stirred at 25 ° C. for 1 hour to obtain a treating agent R6. In this case, the weight calculated as SiO ₂ / the weight calculated as TiO ₂ = 0.87, and the weight calculated as ZrO ₂ / TiO ₂
The converted weight is 0.09.

1 cc of the treating agent R6 was dropped on a glass substrate which had been washed in advance, spin coating was performed, and then 65
A heat treatment was performed at 0 ° C. for 5 minutes to obtain a test piece. The film thickness of the coating provided on this test piece was 77 nm.

[0054]

[Table 1]

[0055]

EFFECTS OF THE INVENTION By using the composition of the present invention, photocatalytic activity, mechanical strength and chemical resistance are excellent by simply applying it directly to a substrate without requiring a special pretreatment such as providing an intermediate layer. Can form a coated film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiji Edo 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture Asahi Glass Co., Ltd. Central Research Laboratory

Claims (4)

[Claims] 1. Ti having an average particle size of less than 100 nm.
O ₂ fine particles, (2) Zr element-containing compound, (3) S
and a compound containing an i element, (2) with respect to (1),
The weight ratio of (3) is (1): ((2) in terms of ZrO ₂ ): ((3) in terms of SiO ₂ ) = 1: 0.02
A composition that is 0.5: 0.2 to 2.5. 2. A method for producing a photocatalytically active coating formed on a substrate, which comprises directly applying the composition of claim 1 and then subjecting the composition to heat treatment. . 3. A substrate having a coating formed using the composition of claim 1. 4. The substrate according to claim 3, wherein the film thickness of the coating is 30 to 300 nm.