Photocatalyst-coated object and photocatalytic coating fluid therefor

(54) Title: BODY COATED FROM (57) Summary:

PHOTOCATALYZER, E, PHOTOCATALYTIC COATING NET (30) Unionist Priority: 26/03/2007 jp 2007-079469,

05/11/2007 JP 2007-127296, 05/11/2007 JP 2007-127296, 03/26/2007

JP 2007-079469 (73) Holder (s): Toto ltd.

(72) Inventor (s): Hironaga Iwata, Junji Kameshima, Koji Omoshiki, MAKOTO HAYAKAWA, Milsuyoshi Kanno, Saloru Kilazaki, Yoji Takaki, Yuki Tanaka (74) Attorney (s): Momsen, Leonardos & Cia.

(86) International Order: pct JP2008055648 of 26/03/2008 (87) International Publication: wo 2oos / i23278de 16/10/2008 < ⁰-1

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TiO2 CONTENT (parts by weight) “PHOTOCATALYTIC COATED BODY, AND PHOTOCATALYTIC COATING LIQUID”

TECHNICAL FIELD

The present invention relates to a photocatalyst-coated body that is superior in climatic resistance, harmful gas decomposition capacity, and various coating properties, particularly suitable for use in exterior building materials and the like. The present invention also relates to a photocatalytic coating liquid for the photocatalyst-coated body.

PREVIOUS ART

Photocatalysts such as titanium oxide have recently been used in various applications such as building exterior materials. The use of the photocatalyst makes it possible to control the light energy to decompose various types of harmful substances and make the surface of a substrate coated with the photocatalyst hydrophilic to allow a stain deposited on the surface to be easily removed with water. The following techniques have been known to produce photocatalyst coated bodies coated with such a photocatalyst.

It is known to use an aqueous dispersion comprising photocatalytic metal oxide particles, a colloidal silica, and a surfactant to impart hydrophilic properties to the surface of a synthetic resin or the like (see, for example, Japanese Patent Publication Published Number 1999-140432 ). In this technique, the hydrophilic properties are enhanced by the addition of a large amount of a surfactant ranging from 10% by weight to 25% by weight. The film thickness is also adjusted to 0.4 pm or less in order to prevent white turbidity that is caused by diffuse reflection of light.

Also known is the formation on the substrate of a coating film comprising a photocatalytic titanium dioxide and a binder silica sol to obtain a photocatalytic body (see, for example, Japanese Patent Published Number 1999-169727). In this technique, the additive amount of the silica sol due to S1O2 is 20 parts to 200 parts by weight of titanium dioxide, and the T1O2 content is high. The particle diameter of the silica sol is as small as 0.1 nm to 10 nm.

It is also known that a photocatalytic coating material is used to form a photocatalytic coating film that transmits 50% or more of light having a wavelength of 500 nm and blocks 80% or more of light having a wavelength of 320 nm (see, for example, in Japanese Published Patent Number 2004-359902). In this technique, a partial organosiloxane hydrolyzate is used as a binder for the photocatalytic coating material, in which the partial organosiloxane hydrolyzate is preferably present in an amount of 5 wt% to 40 wt% of the entire coating composition.

In the meantime, a problem has been conventionally known that when a substrate for a photocatalyst layer is composed of an organic material, the organic material is decomposed or deteriorated due to the photocatalytic activity of the photocatalyst. In order to solve this problem, it is known that an adhesive layer made of a resin modified by silicone or the like is positioned between a layer of photocatalyst and a substrate to protect the substrate against deterioration by the photocatalyst (see, for example, W097 / 00134 ).

SUMMARY OF THE INVENTION

The inventors have currently found that a photocatalyst-coated body that is superior in climatic resistance, in the ability to decompose harmful gas and in several other properties (such as ultraviolet absorptivity, transparency and film resistance) can be obtained while preventing corrosion of a substrate (in particular an organic substrate), by constituting a photocatalyst layer with a specific composition comprising photocatalyst particles and inorganic oxide particles in a specified mass ratio and minimizing a hydrolyzable silicone and a surfactant for zero or small quantities.

Accordingly, an objective of the present invention is to provide a photocatalyst-coated body that is superior in climatic resistance, in the ability to decompose harmful gas, and in several other properties (such as ultraviolet absorptivity, transparency and film resistance) while preventing corrosion of a substrate (in particular an organic substrate). Also an objective of the present invention is to provide a photocatalytic coating liquid to the photocatalyst-coated body.

According to one aspect of the present invention, a photocatalyst-coated body comprising a substrate and a photocatalyst layer positioned on the substrate, the photocatalyst layer comprising:

part or more by mass to less than 20 parts by mass of photocatalyst particles;

parts or more by weight and less than 99 parts by weight of inorganic oxide particles; and zero parts or more by weight and less than 10 parts by weight of a hydrolyzable silicone, provided that a total amount of the photocatalyst particles, the inorganic oxide particles and the hydrolyzable silicone is 100 parts by mass.

According to another aspect of the present invention, a photocatalytic coating liquid used to manufacture the photocatalyst-coated body according to any one of claims 1 to 11 is provided, comprising, in a solvent, part or more by mass less than 20 mass parts of photocatalyst particles;

parts or more by weight and less than 99 parts by weight of inorganic oxide particles; and zero parts or more by weight and less than 10 parts by weight of a hydrolyzable silicone, provided that the total amount of the photocatalyst particles, the inorganic oxide particles and the hydrolyzable silicone is 100 parts by mass.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a graph showing the relationship between the Ab values ​​being a change in color difference between before and after the accelerated test and TiO content ratios₂, measured in Examples 1 to 7, in which the values ​​of the TiO content ratios₂ (parts by mass) represent the ratio of the mass of the titanium dioxide particles to the total amount of the titanium oxide particles and the silica particles.

Fig. 2 is a graph showing the relationship between linear transmittance at 550 nm (%) and film thickness (pm), measured in Examples 12 to 19, in which the 1/99, 5/95, 10 / 90 represent the mass ratio of titanium particle / silica particle.

Fig. 3 is a graph showing the relationship between the shielding rate (%) against ultraviolet (300nm) and the film thickness (pm), measured in Examples 12 to 19, in which the 1/99, 5/95 ratios , 10/90 represent the mass ratio of titanium particle / silica particle.

DETAILED DESCRIPTION OF THE INVENTION Photocatalyst coated body

The photocatalyst-coated body according to the present invention comprises a substrate and a photocatalyst layer positioned on the substrate. The photocatalyst layer includes 1 part or more and less than 20 parts by mass of photocatalyst particles, 70 parts or more and less than 99 parts by mass of inorganic oxide particles, zero parts or more and less than 10 parts by mass of a hydrolyzable silicone as an optional component, and zero part or more and less than 10 parts by mass of a surfactant as an optional component. The total amount of the photocatalyst particles, the particles of inorganic oxide, and the hydrolyzable silicone is 100 parts by mass, and the parts by mass of the surfactant are determined with respect to the 100 parts by mass.

The photocatalyst layer according to the present invention basically comprises 1 part or more and less than 20 parts by mass of photocatalyst particles and 70 parts or more and less than 99 parts by mass of inorganic oxide particles. This constitution makes it possible to obtain a photocatalyst-coated body that is superior in climatic resistance, in the ability to decompose harmful gas, and in several other properties such as ultraviolet absorptivity, transparency and film resistance) while preventing corrosion of a substrate ( in particular an organic substrate). The reason why these effects are performed all together is not clear, but it can be assumed as follows. The following explanation is only a hypothesis, and the present invention is not limited by the following hypothesis. First, since the photocatalyst layer basically comprises two types of particles, ie, the photocatalyst particles and the inorganic oxide particles, there is a lot of space between the particles. In the case of using a large amount of a hydrolyzable silicone widely usable as a binder for a photocatalyst layer, it is considered that the hydrolyzable silicone would block the diffusion of the gas because the space between the particles is narrowly filled. However, the photocatalyst layer of the present invention is free of a hydrolyzable silicone or, alternatively, comprises less than 10 parts by mass of hydrolyzable silicone with respect to the total 100 parts by mass of the photocatalyst particles, inorganic oxide particles and hydrolyzable silicone. For this reason, it is assumed that the space between the particles can be sufficiently ensured. The space thus secured leads to the creation of a structure in which harmful gases such as NO_X and SO_X are readily diffused into the photocatalyst layer. As a result, the harmful gases are supposed to come into effective contact with the photocatalyst particles to be decomposed by the activity of the photocatalyst.

At the same time, it is considered that, since the proportion of photocatalyst particles is considerably less than that of inorganic oxide particles, direct contact of the photocatalyst particles with the substrate can be minimized to suppress corrosion of the substrate (in particular the organic substrate). It is also assumed that the substrate can be damaged by ultraviolet light because the photocatalyst itself absorbs ultraviolet light to reduce the amount of ultraviolet light reaching the substrate. As a result, the photocatalyst layer of the present invention is capable of being formed on a substrate of which at least the surface is composed of an organic material, by direct application without interposition of an intermediate layer to protect the substrate. Thus, since there is no need to form the intermediate layer, it is possible to save the time and cost required to manufacture the catalyst coated bodies. In addition, the photocatalyst layer of the present invention may not comprise a surfactant, but even if the photocatalyst layer comprises the surfactant, the amount of surfactant is adjusted to less than 10 parts by mass with respect to the total 100 parts by mass photocatalyst particles, inorganic oxide particles and hydrolyzable silicone. Through this adjustment, it is assumed that the deterioration in film resistance and the ability to decompose harmful gas is prevented, which is largely caused by the surfactant present. With the various phenomena above occurring all together, it is considered that a photocatalyst-coated body is obtained that is superior in climatic resistance, in noxious gas decomposition capacity, and in several other properties such as ultraviolet absorptivity, transparency and film resistance ) while preventing corrosion of a substrate (in particular an organic substrate).

Substrate

The suitable substrate in the present invention can be various materials on which the photocatalyst layer can be formed, regardless of an organic material or an inorganic material, and the shape of the substrate is not limited. Preferable examples of substrates in view of the material include metals, ceramics, glass, plastics, rubbers, stones, cements, concretes, fibers, fabrics, wood, paper, combinations of these, laminations of these, and those having at least one coated layer on the surface of these. Preferable examples of substrates for application include building materials, building exterior materials; window frames; window glass; structural members; vehicle exterior and coating components; outdoor machine components; apparatus and articles; dustproof coating and masks; traffic signs; various types of dials; advertising pillars; road noise barriers; railroad sound barriers; bridges; exterior components and barrier coating to prevent accidents; internal walls and tunnel lining; insulators; solar cell covers; heat collector covers for solar water heaters; plastic greenhouses, vehicle lamp covers; external lighting apparatus; pedestals; and various outdoor materials such as films, sheets and seals to be fixed in the articles above.

According to a preferred aspect of the present invention, the substrate can have at least the surface composed of an organic material, and include a substrate entirely made of an organic material and a substrate made of an inorganic material whose surface is covered with an organic material (eg, decorative plate). According to the photocatalyst layer of the present invention, corrosion does not easily occur in an organic material, which is sensitive to the activity of the photocatalyst, a photocatalyst-coated body having superior functions can be produced by using the photocatalyst layer alone without an intermediate layer . As a result, since it is not necessary to form the intermediate layer, it is possible to save the time and cost required to manufacture the photocatalyst coated bodies.

Photo-crystal layer and photo-crystal coating liquid to form it

The photocatalyst layer according to the present invention comprises 1 part or more and less than 20 parts by mass of photocatalyst particles, 70 parts or more and less than 99 parts by mass of inorganic oxide particles, zero part or more and less than 10 parts by weight of a hydrolyzable silicone, and zero parts or more and less than 10 parts by weight of a surfactant. The total amount of photocatalyst particles, inorganic oxide particles and hydrolyzable silicone is 100 parts by mass. The photocatalyst layer can be formed by coating the substrate with a photocatalytic coating liquid comprising a solvent and a solute comprising the constituents described above in the mass ratio described above dispersed in the solvent.

According to a preferred aspect of the present invention, the film thickness of the photocatalyst layer is preferably 0.5 pm to 3.0 pm, more preferably 1.0 pm to 2.0 pm. Within this film thickness range, ultraviolet light reaching the interface between the photocatalyst layer and the substrate is sufficiently attenuated, leading to an improvement in climate resistance. In addition, it is possible to increase the amount of photocatalyst particles positioned in the thickness direction of the film although the photocatalyst particle content ratio is less than that of inorganic oxide particles, resulting in an improvement in the ability to decompose harmful gas . In addition, superior properties in ultraviolet absorptivity, transparency and film resistance are provided.

The photocatalyst particles usable in the present invention are not particularly limited as long as they have photocatalyst activity, and particles of various types of photocatalysts can be used. Examples of the photocatalyst particles include metal oxide particles such as titanium oxide particles (T1O2), ZnO, SnC&gt; 2, SrTICh, WO3, Bi₂O₃, and Fe₂C&gt; 3, preferably titanium oxide particles, more preferably anatase titanium oxide particles. Titanium oxide is harmless, chemically stable and available at low cost. Because of its high band gap energy, titanium oxide requires ultraviolet light for photoexcitation and does not absorb visible light in the photoexcitation process. As a result, coloring by complementary color components does not occur. Titanium oxide is available in various forms such as powder, sun, and solution. Any form of titanium oxide can be used as long as it exhibits photocatalyst activity. According to a preferred aspect of the present invention, the photocatalyst particles preferably have an average particle size of 10 nm to 100 nm, more preferably 10 nm to 60 nm. The average particle size is calculated as a numerical mean value obtained by measuring the lengths of 100 randomly selected particles from the particles located within a visible field magnified 200,000 times by a scanning electron microscope. The most suitable particle shape is a perfect sphere, but an elliptical or approximately rounded particle can be used, in which case the particle length is approximately calculated as ((long diameter + short diameter) / 2). Within this range, climate resistance, the ability to decompose harmful gas, and the desired coating properties (such as ultraviolet absorptivity, transparency and film resistance) are effectively exhibited. When a commercially available sun-shaped photocatalyst is used and processed so that the particle diameter becomes 30 nm or smaller, preferably 20 nm or smaller, it is also possible to produce a photocatalyst layer with especially high transparency.

The content of the photocatalyst particles in the photocatalyst layer or in the coating liquid of the present invention is 1 part or more and less than 20 parts by weight, preferably 5 parts to 15 parts by weight, more preferably 5 parts to 10 parts by weight with respect to the total 100 parts by mass of the photocatalyst particles, the inorganic oxide particles and the hydrolyzable silicone. Since the proportion of the photocatalyst particles is adjusted to be low as described above, direct contact of the photocatalyst particles with the substrate is reduced as much as possible, thereby suppressing corrosion of the substrate (in particular the organic material). As a result, climate resistance is supposed to be improved as well. However, the functions of the harmful gas decomposition capacity and the ultraviolet absorptivity to be caused by the photocatalyst activity can also be effectively exhibited.

According to a preferred aspect of the present invention, titania can be added in the photocatalyst layer or in the photocatalytic coating liquid, along with at least one metal selected from the group consisting of vanadium, iron, cobalt, nickel, palladium, zinc, ruthenium, rhodium, lead, copper, silver, platinum and gold and / or a metallic compound of these metals. For the purpose of improving the photocatalytic capacity, this addition can be conducted according to either a method of adding a solution containing a photocatalyst and the metal or metallic compound described above or a method of using a photocatalysis redox reaction to allow the metal or metallic compound is supported on the photocatalyst.

The inorganic oxide particles used in the present invention are not particularly limited as long as they are capable of being combined with the photocatalyst particles to form a layer, and any type of inorganic oxide particles can be used. Examples of such inorganic oxide particles include particles of a simple oxide such as silica, alumina, zirconia, ceria, yttria, boronia, magnesia, calcium, ferrite, amorphous titania and hafnia; and particles of a composite oxide such as barium titanate and calcium silicate, preferably silica particles. These inorganic oxide particles are preferably in an aqueous colloidal form with water as a dispersion medium or in an organosol form of a colloidal dispersion in a hydrophilic solvent such as ethyl alcohol, isopropyl alcohol or ethylene glycol, and colloidal silica it is particularly preferable. According to a preferred aspect of the present invention, the average particle size of the inorganic oxide particles is preferably 10 nm or greater and less than 40 nm, more preferably 10 nm at 30 nm. The average particle size is calculated as a numerical mean value obtained by measuring the lengths of 100 randomly selected particles from the particles located within a visible field magnified 200,000 times by a scanning electron microscope. The most suitable particle shape is a perfect sphere, but an elliptical or approximately rounded particle can be used, in which case the particle length is approximately calculated as ((long diameter + short diameter) / 2). Within this range, climate resistance, the ability to decompose harmful gas, and the desired coating properties (such as ultraviolet absorptivity, transparency and film resistance) are effectively exhibited. In particular, it is also possible to produce a layer of transparent photocatalyst with particularly high adhesion.

The content of the inorganic oxide particles in the photocatalyst layer or in the coating liquid of the present invention is 70 parts or more and less than 99 parts by weight, preferably 80 parts to 95 parts by mass, more preferably 85 parts to 95 parts by mass, in addition preferably 90 parts to 95 parts by mass, with respect to the total 100 parts by mass of the photocatalyst particles, inorganic oxide particles and hydrolyzable silicone.

The photocatalyst layer of the present invention is preferably substantially free of hydrolyzable silicone, more preferably completely free of hydrolyzable silicone. Hydrolyzable silicone is a generic name for organosiloxane having an alkoxide group and / or a partial hydrolysis condensate of the organosiloxane. However, hydrolyzable silicone can be added as an optional component at such a level that the noxious gas decomposition capability of the present invention can be guaranteed. Accordingly, the content of hydrolyzable silicone, on a silica base is zero parts or more and less than 10 parts by weight, preferably 5 parts or less by weight, more preferably zero parts by weight, with respect to the total 100 parts by mass photocatalyst particles, inorganic oxide particles and hydrolyzable silicone. A tetrafunctional silicone compound is often used as a hydrolyzable silicone, and is commercially available, for example, as ethyl silicate 40 (oligomer, R is an ethyl group), ethyl silicate 48 (oligomer, R is an ethyl group), methyl silicate 51 (oligomer , R is a methyl group), all of which are produced by Colcoat Co. Ltd.

The surfactant usable in the present invention can be added to the photocatalyst layer in an amount of zero parts or more by weight and less than 10 parts by weight as an optional component, preferably zero parts to 8 parts by mass, more preferably zero parts to 6 parts by mass. One of the effects of the surfactant is the leveling properties on the substrate. Therefore, the amount of surfactant can be appropriately determined within the aforementioned range, depending on a combination of the coating liquid and the substrate. In this case, the lower limit of the surfactant content can be 0.1 part by mass. The surfactant is an effective component to improve the coating properties of the photocatalytic coating liquid. In the photocatalyst layer formed after being coated, however, the surfactant corresponds to the inevitable impurities that do not contribute to the benefits provided by the photocatalyst coated body of the present invention. Accordingly, the surfactant can be used within the above content range depending on the coating properties required for the photocatalytic coating liquid. If the coating properties are not considered, substantially none or completely no surfactants may be present. A surfactant to be used can be appropriately chosen due to the dispersion stability of the photocatalyst or inorganic oxide particles or the coating properties when the coating is applied to an intermediate layer. Preferred examples of surfactant include nonionic surfactants, more preferably ether type nonionic surfactants, ester type nonionic surfactants, poly (alkylene glycol) nonionic surfactants, fluorinated nonionic surfactants, and non-ionic surfactants -ions based on silicon.

The photocatalytic coating liquid of the present invention can be obtained by dispersing the photocatalyst particles, inorganic oxide particles, and optionally the hydrolyzable silicone and the surfactant in a solvent in the specific proportion mentioned above. Any type of solvent can be used in which the constituents described above can be appropriately dispersed, and can be water or an organic solvent. The solid concentration of the photocatalytic coating liquid of the present invention is not particularly limited, but is preferably 1 wt% to 10 wt% to facilitate coating. Analysis of the constituents in the photocatalyst composition can be conducted by using ultrafiltration to separate the coating liquid into particle components and a filtrate to be analyzed by infrared spectroscopic analysis, gel permeation chromatography, spectrochemical analysis by fluorescence-ray-ray respectively. X or similar for spectral analysis.

Manufacturing process

The photocatalyst-coated body of the present invention can be readily manufactured by applying the photocatalytic coating liquid of the present invention to the substrate. Application of the photocatalyst layer can be conducted according to conventional methods, which include application by brush, roller, spray, roller coat, dip coating, screen printing, electrolytic deposition, vapor deposition, and the like. The coating liquid after being applied to the substrate can be dried at room temperature or, if necessary, can be dried by heating. Since the photocatalyst layer of the photocatalyst-coated body of the present invention is less likely to corrode organic materials, which are vulnerable to photocatalyst activity, it is possible to use a photocatalyst layer alone without an intermediate layer to produce a photocatalyst coated body having superior functions. So it is possible to save time and cost required to manufacture the photocatalyst coated bodies due to the non-need to form the intermediate layer.

EXAMPLES

The present invention will be described in detail with reference to the following Examples, but the present invention is not limited to these Examples.

The raw materials used to produce a photocatalytic coating liquid in the following Examples will be described below. Photocatalyst particles

- Aqueous dispersion of titania (average particle diameter: 30 nm to 60 nm, basic).

Inorganic oxide particles

- Aqueous dispersion type colloidal silica (produced by Nissan Chemical Industriais Ltd., trade name; SNOWTEX 50, particle diameter: 20 nm to 30 nm, solids content: 48%) (used in Examples 1 to 19 and Examples 24 to 27).

- Colloidal silica of the aqueous dispersion type (produced by Nissan Chemical Industriais Ltd., trade name: SNOWTEX 40, particle diameter: 10 mm at 20 nm, solids content: 40%) (used in Example 20).

- Colloidal silica of the aqueous dispersion type (produced by Nissan Chemical Industriais Ltd., commercial name: SNOWTEX 50, particle diameter: 20 nm to 30 nm, solids content: 48%) (used in Example 21).

- Colloidal silica of the aqueous dispersion type (produced by Nissan Chemical Industriais Ltd., commercial name: SNOWTEX S, particle diameter: 8 nm to 11 nm, solids content: 30%) (used in Example 22).

- Colloidal silica of the aqueous dispersion type (produced by Nissan Chemical Industriais Ltd., trade name: SNOWTEX XS, particle diameter: 4 nm to 6 nm, solids content: 20%) (used in Example 23). Hydrolyzable silicone

- Tetramethoxy silane polycondensate (produced by Tama Chemicals Co .; Ltd., trade name: M silicate 51).

Surfactant

- Polyether modified silicone surfactant (produced by Shin-Etsu Chemical Co., Ltd., trade name: silicone-modified polyether (KF-643)).

Examples 1-7: Assessment of climate resistance

A photocatalyst-coated body having a photocatalyst layer was produced as follows. A body coated with colored organic material was prepared as a substrate. The body coated with colored organic material was obtained by coating a flat glass plate with a general purpose acrylic silicone with an added carbon black powder, and then it was sufficiently dry and cured. On the other hand, a photocatalytic coating liquid was prepared by mixing an aqueous dispersion of titania as a photocatalyst, a colloidal silica of the aqueous dispersion as an inorganic oxide, water as a solvent, and a silicone surfactant modified with polyether all added. in the proportions shown in Table 1. It should be noted that the photocatalytic coating liquid does not include hydrolyzable silicone. The total solid concentration of the photocatalyst and inorganic oxide in the photocatalytic coating liquid was 5.5% by weight.

The photocatalytic coating liquid thus obtained was applied, by spray coating, to the body coated with colored organic material that had previously been heated to 50 ° C. The photocatalytic coating liquid was then dried for 5 minutes at 120 ° C. In this mode, a photocatalyst layer was formed to obtain a photocatalyst coated body. When the film thickness of the photocatalyst layer was measured with a scanning electron microscope, the film thickness was about 0.5 nm in each of Examples 1 to 7.

A climatic test was conducted on the photocatalyst coated body thus obtained with the size of 50 mm X 100 mm as described below. The photocatalyst-coated body was positioned inside a climate meter in sunlight (produced by SUGA TEST

INSTRUMENTS CO., LTD., S-300C) according to JIS B7753. After a lapse of 300 hours, a test piece was removed to measure a color difference before and after the accelerated test with Color Meter ZE2000 produced by Nippon Denshoku Instruments Co., Ltd. The Ab values ​​of the measurements were compared to assess the degree of color change.

The results are shown in Table 1 and Fig. 1, in which

G means that the color showed little change and NG means that the Ab values ​​became positive (yellow discoloration). As shown in Table 1 and Fig. 1, the photocatalyst-coated body has been found to have sufficient weather resistance by adjusting the photocatalyst content in the photocatalyst layer to less than 20 parts by mass, preferably 15 parts or less by mass , even when the photocatalyst layer is formed on the organic substrate.

Table 1

<td>Example At the.</td><td>Titanium oxide particles (part by mass)</td><td>Silica particles (part by mass)</td><td>Surfactant (part by mass)</td><td>Ab</td>

<td> 1</td><td> 1</td><td> 99</td><td> 6</td><td>G</td>

<td> 2</td><td> 5</td><td> 95</td><td> 6</td><td>G</td>

<td> 3</td><td> 10</td><td> 90</td><td> 6</td><td>G</td>

<td> 4</td><td> 15</td><td> 85</td><td> 6</td><td>G</td>

<td> 5</td><td> 18</td><td> 82</td><td> 6</td><td>G</td>

<td> 6*</td><td> 20</td><td> 80</td><td> 6</td><td>NG</td>

<td>γ *</td><td> 30</td><td> 70</td><td> 6</td><td>NG</td>

*: Comparative Examples

Examples 8-11: Assessment of harmful gas decomposition capacity

A photocatalyst-coated body having a photocatalyst layer was produced as follows. A body coated with colored organic material was prepared as a substrate, the body coated with colored organic material was obtained by coating a flat glass plate with a general purpose acrylic silicone with added carbon black powder, and then sufficiently dry and healed. On the other hand, a photocatalytic coating liquid was prepared by mixing an aqueous dispersion of titania as a photocatalyst, a colloidal silica of the aqueous dispersion as an inorganic oxide, water as a solvent, a polyether modified silicone surfactant, and a polycondensate of tetramethoxy silane as a hydrolyzable silicone all added in the proportions shown in Table 2. It should be noted that the photocatalytic coating liquid in Examples 8 and 10 does not include hydrolyzable silicone. The total solid concentration of the photocatalyst and inorganic oxide in the photocatalytic coating liquid was 5.5% by weight.

The photocatalytic coating liquid thus obtained was applied, by spray coating, to the body coated with colored organic material which had been heated to 50 ° C. The photocatalytic coating liquid was then dried for 5 minutes at 120 ° C. In this way, a photocatalyst layer was formed to obtain a photocatalyst coated body. When the film thickness (pm) of the photocatalyst layer was measured with a scanning electron microscope, the film thickness was about 1 pm in each of Examples 8 to 11.

A gas decomposition test was conducted on the photocatalyst coated body thus obtained with the size of 50 mm X 100 mm as described below. As a pretreatment, the photocatalyst-coated body was irradiated with 1 mW / cm BLB light for 12 hours or more. The coated body sample was placed inside a reactor according to JIS RI701. Air adjusted to 50% relative humidity at 25 ° C was mixed with NO gas to a level of about 1,000 ppb, and was introduced into the reactor shielded against light for 20 minutes. With the gas being introduced, the BLB light was applied at 3 mW / cm² for 20 minutes. The reactor was then again shielded against light in a condition in which the gas is introduced. The amount of NO_X removed was calculated from NO concentrations and NO2 concentrations before and after irradiation with BLB light, according to the following equation:

The amount of NO_X removed = [NO (after BLB irradiation) NO (in BLB irradiation)] - [NO₂ (in BLB irradiation) - NO₂ (after BLB irradiation)]

The results are shown in Table 2, in which G means that the amount of NO_X removed is 400 ppb or more and NG means that the amount of NO_X removed is 10 ppb or less. As shown in Table 2, it has been verified that satisfactory NO decomposition_X was demonstrated by the photocatalyst layer comprising the photocatalyst particles and inorganic oxide and being substantially free of hydrolyzable silicone. On the other hand, it has been found that the photocatalyst layer comprising 10 parts by mass of hydrolyzable silicone has lost its ability to decompose NO_X.

Table 2

<td>Ex.</td><td>Titanium oxide particles (PEM)</td><td>Silica particles (PEM)</td><td>Silicone hydrolyzable (PEM)</td><td>Surfactant (PEM)</td><td>NO amount_X removed</td>

<td> 8</td><td> 10</td><td> 90</td><td> 0</td><td> 6</td><td>G (461 ppb)</td>

<td> 9*</td><td> 10</td><td> 80</td><td> 10</td><td> 6</td><td>NG (2 ppb)</td>

<td> 10</td><td> 15</td><td> 85</td><td> 0</td><td> 6</td><td>G (532 ppb)</td>

<td> 11</td><td>IS</td><td> 80</td><td> 5</td><td> 6</td><td>G (441 ppb)</td>

PEM: Bulk part *: Comparative example.

Examples 12-19: Measurement of linear transmittance and UV shielding rate A photocatalyst coated body having a photocatalyst layer was produced as follows. A flat glass plate with 94% transmittance at 550 nm wavelength was prepared as a substrate. On the other hand, a photocatalytic-coated liquid was prepared by mixing an aqueous dispersion of titania as a photocatalyst, a colloidal silica of the aqueous dispersion type as an inorganic oxide having an average particle diameter ranging from 20 nm to 30 nm, water as a solvent, and a polyether modified silicone surfactant all added in the proportions shown in Table 3. It should be noted that the photocatalytic coating liquid does not include hydrolyzable silicone. The total solid concentration of the photocatalyst and inorganic oxide in the photocatalytic coating liquid was 5.5% by weight.

The photocatalytic coating liquid thus obtained was applied, by spray coating, to the body coated with colored organic material which had been heated to 50 ° C. The photocatalytic coating liquid was then dried for 5 minutes at 120 ° C. In this way, a photocatalyst layer was formed to obtain a photocatalyst coated body. When the film thickness (pm) of the photocatalyst layer was measured with a scanning electron microscope, values ​​were obtained as shown in Table 3.

Measurements of linear transmittance at 550 nm and shielding rate against ultraviolet (300 nm) were conducted in a 50 mm X 100 mm photocatalyst-coated body as described below using a UV / VIS / NIR spectrophotometer (produced by Shimadzu Corporation, UV-3150).

The results are shown in Table 3 and Figs. 2 and 3. Evaluation of linear transmittance and ultraviolet shielding rate was conducted according to the following criteria.

&lt;Linear transmittance&gt;

A: linear transmittance at 550 nm is 97% or more.

B: linear transmittance at 550 nm is 95% or more and less than 97%.

C: linear transmittance at 550 nm is less than 95% &lt;UV shielding rate&gt;

A: UV shielding rate (300 nm) 80% or more.

B: UV shielding rate (300 nm) 30% or more and less than 80%.

C: UV shielding rate (300 nm) less than 30%

As shown in Table 3, Fig. 2 and Fig. 3, it has been verified that it is possible to sufficiently shield against ultraviolet, which causes degradation of the organic substance, and to guarantee transparency, by adjusting the film thickness to 3 pm or less when the content of photocatalyst in the photocatalyst layer varies from 5 parts to 15 parts by mass.

Table 3

<td>Ex.</td><td>Titanium oxide particles (PEM)</td><td>Silica particles (PEM)</td><td>Surfactant (PEM)</td><td>Thickness of film</td><td>Linear r e r tance (550 nm)</td><td>UV shielding rate (300 nm)</td>

<td> 12</td><td> 5</td><td> 95:</td><td> 6</td><td> 0,5</td><td>THE</td><td>B</td>

<td> 13</td><td> 5</td><td> 95</td><td> 6</td><td> 1,5</td><td>THE</td><td>B</td>

<td> 14</td><td> 10</td><td> 90</td><td> 6</td><td> 0,5</td><td>THE</td><td>B</td>

<td> 15</td><td> 10</td><td> 90</td><td> 6</td><td> 1,5</td><td>THE</td><td>THE</td>

<td> 16</td><td> 5</td><td> 95</td><td> 6</td><td> 3</td><td>B</td><td>THE</td>

<td> 17</td><td> 10</td><td> 90</td><td> 6</td><td> 3</td><td>B</td><td>THE</td>

<td> 18</td><td> 1</td><td> 99</td><td> 6</td><td> 0,5</td><td>THE</td><td>ç</td>

<td> 19</td><td> 1</td><td> 99</td><td> 6</td><td> 1,5</td><td>THE</td><td>Ç</td>

PEM: Bulk part

Examples 20-23: Turbidity measurement

A photocatalyst-coated body having a photocatalyst layer was produced as follows. A flat glass plate with 94% transmittance at 550 nm wavelength was prepared as a substrate. On the other hand, a photocatalytic coating liquid was prepared by mixing an aqueous dispersion of titania as a photocatalyst, a colloidal silica of the aqueous dispersion type as an inorganic oxide having various average particle diameters as shown in Table 4, water as a solvent , and a polyether modified silicone surfactant all added in the proportions shown in Table 4. It should be noted that the photocatalytic coating liquid does not comprise hydrolyzable silicone. The total solid concentration of the photocatalyst and inorganic oxide in the photocatalytic coating liquid was 5.5% by weight.

The photocatalytic coating liquid thus obtained was applied to the substrate described above by coating by rotation at 1000 rpm for 10 seconds, and then dried for 5 minutes at 120 ° C to form a photocatalyst layer. Turbidity was measured in a 50 mm X 100 mm photocatalyst-coated body thus obtained by using a turbidity meter (produced by Gardner Corporation, haze-gard plus).

The results are shown in Table 4. As shown in Table 4, it has been found that the turbidity value can be reduced to less than 1% as long as transparency is guaranteed by adjusting the particle diameter of the metal oxide particles in the photocatalyst layer to 10 nm to 30 nm.

Table 4

<td>Ex.</td><td>Titanium oxide particles (PEM)</td><td>Silica particles (PEM)</td><td>Silica particle diameter (nm)</td><td>Surfactant (PEM)</td><td>Turbidity (%)</td>

<td> 20</td><td> 10</td><td> 90</td><td> 10-20</td><td> 6</td><td> 0,68</td>

<td> 21</td><td> 10</td><td> 90</td><td> 20-30</td><td> 6</td><td> 0,48</td>

<td> 22</td><td> 10</td><td> 90</td><td> 8-11</td><td> 6</td><td> 1,11</td>

<td> 23</td><td> 10</td><td> 90</td><td> 4-6</td><td> 6</td><td> 1,22</td>

PEM: Bulk part

Examples 24-27: Assessment of influence by adding surfactant

A photocatalyst-coated body having a photocatalyst layer was produced as follows. A body coated with colored organic material was prepared as a substrate. The body coated with colored organic material was obtained by coating a flat glass plate with a general purpose acrylic silicone with an added carbon black powder, and then sufficiently dry and cured. On the other hand, a photocatalytic coating liquid was prepared by mixing an aqueous dispersion of titaniums as a photocatalyst, a colloidal silica of the aqueous dispersion type as an inorganic oxide, water as a solvent, and a polyether modified silicone surfactant all added in the proportions shown in Table 5. It should be noted that the photocatalytic coating liquid does not comprise hydrolyzable silicone. The total solid concentration of the photocatalyst and inorganic oxide in the photocatalytic coating liquid was 5.5% by weight.

The photocatalytic coating liquid thus obtained was applied, by spray coating, to the body coated with colored organic material that had been heated to 50 ° C to 60 ° C. The photocatalytic coating liquid was dried for 5 minutes at 120 ° C. In this way, a photocatalyst layer was formed to obtain a photocatalyst coated body. When the film thickness (pm) of the photocatalyst layer was measured with a scanning electron microscope, the film thickness was about 1 pm in each of Examples 24 to 27.

A gas decomposition test was conducted on the photocatalyst coated body thus obtained with the size of 50 mm X 100 mm as described below. As a pre-treatment, the photocatalyst-coated body was irradiated with BLB light at 1 mW / cm² for 12 hours or more. The coated body sample was placed inside a reactor according to JIS RI701. Air adjusted to 50% relative humidity at 25 ° C was mixed with NO gas to a level of about 1,000 ppb, and was introduced into the reactor shielded against light for 20 minutes. With the gas being introduced, the BLB light was applied at 3 mW / cm for 20 minutes. The reactor was then again shielded against light in a condition in which the gas is introduced. The amount of NO_X removed was calculated from NO concentrations and NO concentrations₂ before and after irradiation with BLB light, according to the following equation:

The amount of NO_X removed = [NO (after BLB irradiation) NO (in BLB irradiation)] - [NO₂ (in BLB irradiation) - NO₂ (after BLB irradiation)]

The results are shown in Table 5, in which the NO removal efficiencies_X are shown with respect to removal efficiency of 100 in Example 25. As shown in Table 5, increasing the amount of surfactant has been found to cause reduction in removal efficiency.

Table 5

<td>Ex.</td><td>Titanium oxide particles (PEM)</td><td>Silica particles (PEM)</td><td>Surfactant (PEM)</td><td>NO removal efficiencies_X(Ex. 25 is 100)</td>

<td> 24</td><td> 10</td><td> 90</td><td> 0</td><td> 98</td>

<td> 25</td><td> 10</td><td> 90</td><td> 6</td><td> 100</td>

<td> 26*</td><td> 10</td><td> 90</td><td> 10</td><td> 85</td>

<td> 27*</td><td> 10</td><td> 90</td><td> 33.3</td><td> 79</td>

PEM: Bulk part.