JP2001081948A - Building material for exterior wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a building material for an exterior wall having self- cleaning properties and easily cleanable properties. SOLUTION: The building material for the exterior wall has a surface layer containing photocatalytic oxide particles on the surface of a building-material base body for the exterior wall, the surface layer can be manufactured by forming an amorphous titanium oxide layer on the surface of the base body, baking the amorphous titanium oxide layer at a temperature higher than the crystallization of anatase and phase-changing amorphous titanium oxide into anatase type titanium oxide, the building material displays a hydrophilic nature of 10 deg. or less by conversion into a contact angle with water in response to the photo-excitation of the photocatalytic oxide particles, and an adhesive deposit or a contaminant is washed away by rain drops or washed easily with water when the surface of the building material for the exterior wall is exposed to a rainfall.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a building material for an outer wall which can be self-cleaned (self-cleaning) by rainfall and a building material for an outer wall which can be easily cleaned by water washing.

[0002]

2. Description of the Related Art The outer wall of a high-rise building or the like is exposed to combustion products such as dust and exhaust gas contained in the air, dirt eluted from a sealant located above, and pollutants discharged from an exhaust port of the building. Stained by hydrophobic stains. These hydrophobic stains are light black and significantly impair the aesthetics of the building. further,
Attempts to clean high-rise building outer walls are work at heights and are labor intensive as well as dangerous.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a building material for an outer wall which can be cleaned by rainfall or water washing.

[0004]

SUMMARY OF THE INVENTION The present invention is based on the discovery that, in a member having a surface layer containing a photocatalyst formed thereon, when the photocatalyst is photoexcited, the surface of the member is highly hydrophilized. This phenomenon is considered to proceed by the following mechanism. That is, when light having energy equal to or greater than the energy gap between the upper end of the valence band and the lower end of the conduction band of the photocatalyst is irradiated on the photocatalyst, the electrons in the valence band of the photocatalyst are excited to generate conduction electrons and holes. By either or both actions, polarities are probably imparted to the surface and polar components such as water and hydroxyl groups are collected. Then, one or both of conduction electrons and holes and the above-mentioned polar component cooperate with each other to cut off a chemical bond between the surface and the contaminant chemically adsorbed on the surface, and to cause a chemical adsorbed water on the surface. Is adsorbed, and a physically adsorbed water layer is formed thereon. Further, once the surface of the member is highly hydrophilized, the hydrophilicity of the surface is maintained for a certain period even if the member is kept in a dark place.

According to the present invention, there is provided a self-cleaning exterior wall building material having a surface layer containing substantially transparent photocatalytic oxide particles on the surface of the exterior wall building material substrate. By providing a surface layer containing photocatalytic oxide particles,
In response to the photoexcitation of the photocatalyst, the surface of the surface layer becomes hydrophilic, so that when the exterior wall surface is exposed to rain, attached deposits and / or contaminants are washed away by raindrops.

The present invention provides an easy-cleaning exterior wall building material having a surface layer containing substantially transparent photocatalytic oxide particles on the surface of the exterior wall building material substrate. By providing the surface layer containing the photocatalytic oxide particles, the surface of the surface layer exhibits hydrophilicity in response to the photoexcitation of the photocatalyst, and the surface of the building material for the outer wall is easily washed with water, and is rinsed with water. And it is cleaned with a simple water wipe.

[0007]

Next, a specific configuration of the present invention will be described. As shown in FIG. 1 or FIG. 2, a photocatalyst (crystal)
A layer containing a conductive oxide or the like is formed. With such a surface structure, the surface of the building material for the outer wall is highly hydrophilized in response to the photoexcitation of the photocatalyst. Thereby,
The rainfall causes sediment and / or contaminants adhering to the surface of the surface layer to be washed away by the raindrops. Furthermore, in the case where the above surface structure is provided on the surface of the building material for an outer wall, the deposits and / or contaminants adhering to the surface of the surface layer can be easily washed with water, and when sunny days continue. However, it can be cleaned by water rinsing or watering.

In FIG. 1, the surface layer comprises only photocatalytic oxide particles. In this case, since the photocatalyst is made of an oxide, the oxide shows hydrophilicity in a state where the pollutants in the environment are not adsorbed. Therefore, the contaminants are eliminated by the photoexcitation action to form an adsorbed water layer. Thus, it is easy to exhibit hydrophilicity and a uniform water film can be formed. In FIG. 2, M represents a metal element. Therefore, in the case of FIG. 2, the outermost surface is made of a general inorganic oxide. Also in this case, the oxide shows hydrophilicity in a state where the pollutant in the environment is not adsorbed, so that the pollutant is eliminated by the photoexciting action of the photocatalytic oxide mixed into the surface layer other than the inorganic oxide. By forming the adsorbed water layer, a uniform water film can be formed.

[0009] The building material base for an outer wall to which the present invention can be applied includes:
Glazed tile, unglazed tile, brick, crystallized glass, glass block, concrete, stone, wood; lightweight cellular concrete board, asbestos cement calcium silicate board, precast reinforced concrete board, asbestos slate board, pulp cement board, gypsum board board, etc. Acrylic resin, urethane resin, polyester, silicone,
Decorative inorganic building materials coated with resin paints such as fluororesin and acrylic silicone resin; acrylic resin, urethane resin, on the surface layer of metal base materials such as aluminum, stainless steel and steel
A coated steel plate coated with a resin paint such as polyester, silicone, fluororesin, or acrylic silicone resin; a plastic plate such as an acrylic plate or a polycarbonate plate, or a coated product thereof can be suitably used.

[0010] A photocatalyst emits light (excitation light) having an energy (ie, a shorter wavelength) larger than the energy gap between the conduction band and the valence band of the crystal, and emits electrons in the valence band. It refers to a substance that can generate conduction electrons and holes by excitation (photoexcitation), and the photocatalytic titanium oxide refers to, for example, crystalline titanium oxide such as anatase-type titanium oxide and rutile-type titanium oxide. Here, sunlight can be suitably used as a light source used for photoexcitation of the photocatalyst. In order for the substrate surface to be highly hydrophilized by photoexcitation of the photocatalyst, the illuminance of the excitation light is 0.001 mW / cm.
^The number is preferably ² or more, but is preferably 0.01 mW / cm ² or more, and more preferably 0.1 mW / cm ² or more.

The thickness of the surface layer containing the photocatalytic titanium oxide is preferably 0.4 μm or less. Then, cloudiness due to irregular reflection of light can be prevented, and the surface layer becomes substantially transparent. Further, it is more preferable that the thickness of the surface layer containing the photocatalytic titanium oxide be 0.2 μm or less. Then, it is possible to prevent the surface layer from being colored by light interference. Also, the thinner the surface layer, the better its transparency. Further, when the film thickness is reduced, the wear resistance of the surface layer is improved. The surface of the surface layer may be further provided with a wear-resistant or corrosion-resistant protective layer capable of being made hydrophilic and other functional films.

The surface layer preferably has a refractive index not so high as compared with the substrate. Preferably, the refractive index of the surface layer is 2 or less. Then, light reflection at the interface between the substrate and the surface layer and the interface between the surface layer and air can be suppressed. To reduce the refractive index of the surface layer to 2 or less, another substance having a refractive index of 2 or less is added to the photocatalytic titanium oxide. Here, as another substance having a refractive index of 2 or less,
For example, calcium carbonate (refractive index 1.6), calcium hydroxide (refractive index 1.6), magnesium carbonate (refractive index 1.5), strontium carbonate (refractive index 1.5), dolomite (refractive index 1.7) ), Calcium fluoride (refractive index 1.4), magnesium fluoride (refractive index 1.4), silica (refractive index 1.5), alumina (refractive index 1.6), silica sand (refractive index 1.6) ), Montmorillonite (refractive index 1.
5), kaolin (refractive index 1.6), sericite (refractive index 1.6), zeolite (refractive index 1.5), tin oxide (refractive index 1.9) and the like can be added to the surface layer.

A metal such as Ag, Cu and Zn can be added to the surface layer. The surface layer to which the metal is added can kill bacteria and fungi attached to the surface even in a dark place.

The surface layer includes Pt, Pd, Ru, R
A platinum group metal such as h, Ir, Os can be added. The surface layer to which the metal is added can enhance the oxidation-reduction activity of the photocatalyst and improve the deodorizing and purifying action and the like. In addition, when a solid acid is added in addition to the photocatalyst, the acidity of the solid acid is improved by the addition of a platinum group metal, so that the hydrophilicity is also improved, and the formation of a water film on the attached water is further promoted. Hydrophilicity retention when the photocatalyst is not irradiated with the excitation light for a long time is also improved. Mo may be added to the surface layer. Also in this case, since the acidity of the solid acid is improved by the addition, the hydrophilicity maintenance property is also improved, the formation of a water film of the attached water is further promoted, and the hydrophilicity maintenance property when the photocatalyst is not irradiated with the excitation light for a long period of time. Also improve.

When the base material is a glass containing an alkali network modifying ion such as sodium (soda lime glass, side-by-side glass, etc.), an intermediate layer such as silica may be formed between the base material and the surface layer. Good. Then, the diffusion of the alkali network modifying ions from the base material to the surface layer during the firing is prevented, and the photocatalytic function is more effectively exhibited.

The term "hydrophilic" refers to the property of being easily conformed when water is dropped on the surface, and generally refers to a state where the water wetting angle is less than 90 °. The term “high hydrophilicity” in the present invention refers to a property that is highly compatible when water is dropped on the surface, and more specifically, a state where the water wetting angle is about 10 ° or less. In particular, as disclosed in PCT / JP96 / 00734, the water wetting angle is preferably 10 ° or less, more preferably 5 ° or less, as disclosed in PCT / JP96 / 00734.

In the present invention, the solid acid includes sulfuric acid-supported Al.
₂ O ₃ , sulfuric acid supported TiO ₂ , sulfuric acid supported ZrO ₂ , sulfuric acid supported S
nO ₂ , sulfuric acid supported Fe ₂ O ₃ , sulfuric acid supported SiO ₂ , sulfuric acid supported HfO ₂ , TiO ₂ / WO ₃ , WO ₃ / SnO ₂ , WO ₃ / Z
_{rO 2, WO 3 / Fe 2} O 3, SiO 2 · Al 2 O 3, TiO 2
/ SiO ₂ , TiO ₂ / Al ₂ O ₃ , TiO ₂ / ZrO _{2 and the} like can be suitably used.

Next, a method for forming the surface layer will be described. First, a production method in the case where the surface layer is made of only a photocatalytic oxide will be described with reference to an example in which the photocatalyst is an anatase type titanium oxide. In this case, there are roughly three methods. One method is a sol coating and firing method, the other method is an organic titanate method, and the other method is an electron beam evaporation method. (1) Sol coating and firing method Anatase type titanium oxide sol is
The composition is applied to the surface of the base material by a method such as a spray coating method, a dip coating method, a flow coating method, a spin coating method, and a roll coating method, and is baked. (2) Organic titanate method A hydrolysis inhibitor (hydrochloric acid, ethylamine, etc.) is added to an organic titanate such as titanium alkoxide (tetraethoxytitanium, tetramethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, etc.), titanium acetate, titanium chelate, etc. , After diluting with a non-aqueous solvent such as alcohol (ethanol, propanol, butanol, etc.) and then partially or completely allowing hydrolysis to proceed, the mixture is spray-coated, dip-coated, It is applied by a flow coating method, a spin coating method, a roll coating method or the like, and dried. By drying, hydrolysis of the organic titanate is completed and titanium hydroxide is generated,
A layer of amorphous titanium oxide is formed on the surface of the substrate by dehydration-condensation polymerization of titanium hydroxide. Thereafter, the titanium oxide is calcined at a temperature equal to or higher than the crystallization temperature of anatase, so that the amorphous titanium oxide undergoes a phase transition to anatase-type titanium oxide. (3) Electron Beam Evaporation Method An amorphous titanium oxide layer is formed on the surface of a base material by irradiating a titanium oxide target with an electron beam. Thereafter, the titanium oxide is calcined at a temperature equal to or higher than the crystallization temperature of anatase, so that the amorphous titanium oxide undergoes a phase transition to anatase-type titanium oxide.

Next, the case where the surface layer is composed of a photocatalytic oxide and silica will be described with reference to the case where the photocatalyst is anatase type titanium oxide. In this case, for example, there are the following three methods. One method is a sol coating and firing method, the other is an organic titanate method, and the other is a tetrafunctional silane method. (1) Sol coating and baking method A mixture of anatase-type titanium oxide sol and silica sol is applied to the surface of a substrate by a method such as a spray coating method, a dip coating method, a flow coating method, a spin coating method, and a roll coating method, and then fired. I do. (2) Organic titanate method Titanium alkoxide (tetraethoxytitanium, tetramethoxytitanium, tetrapropoxytitanium, tetrabutoxytitanium, etc.), a titanium acetate such as titanium acetate, titanium chelate, etc. are combined with a hydrolysis inhibitor (hydrochloric acid, ethylamine, etc.) and silica sol. Add alcohol (ethanol, propanol, butanol, etc.)
After dilution with a non-aqueous solvent such as, after partially or completely proceeding hydrolysis, the mixture is spray-coated, dip-coated,
It is applied by a flow coating method, a spin coating method, a roll coating method or the like, and dried. By drying, hydrolysis of the organic titanate is completed to produce titanium hydroxide, and a layer of amorphous titanium oxide is formed on the surface of the base material by dehydration-condensation polymerization of titanium hydroxide. Thereafter, the titanium oxide is calcined at a temperature equal to or higher than the crystallization temperature of anatase, so that the amorphous titanium oxide undergoes a phase transition to anatase-type titanium oxide. (3) Tetrafunctional silane method A mixture of tetraalkoxysilane (tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetramethoxysilane, etc.) and anatase-type titanium oxide sol is spray-coated on the surface of the base material, and dip-coated. After applying by a method such as a flow coating method, a spin coating method, or a roll coating method, and hydrolyzing to form a silanol if necessary, the silanol is subjected to dehydration polycondensation by a method such as heating.

Next, the case where the surface layer is composed of a photocatalytic oxide and a solid acid will be described with reference to the case where the photocatalyst is anatase type titanium oxide and the solid acid is TiO2 / WO3. In this case, a method of mixing an ammonia solution of tungstic acid and an anatase-type titanium oxide sol and, if necessary, diluting the mixture with a diluting liquid (water, ethanol, etc.) on the surface of the base material by spray coating, dip coating, or the like. It is applied by a method such as a flow coating method, a spin coating method, and a roll coating method, and is baked. Another method is to form an amorphous titanium oxide film by electron beam evaporation, hydrolysis and dehydration condensation polymerization of an organic titanate such as titanium alkoxide, titanium acetate, and titanium chelate, then apply tungstic acid, and then apply the amorphous material. Heat treatment is performed at a temperature at which titanium oxide is crystallized and a TiO ₂ / WO ₃ composite oxide is formed.

Next, the case where the surface layer is made of a photocatalytic oxide and silicone will be described with reference to the case where the photocatalyst is anatase type titanium oxide. The method in this case is to mix a coating of uncured or partially cured silicone or a silicone precursor with an anatase-type titanium oxide sol, hydrolyze the silicone precursor if necessary, and then mix the mixture. Is applied to the surface of the substrate by spray coating, dip coating, flow coating, spin coating, roll coating, etc., and the hydrolyzate of the silicone precursor is subjected to dehydration condensation polymerization by heating, etc. Then, a surface layer composed of anatase type titanium oxide particles and silicone is formed. In the formed surface layer, at least a part of the organic group bonded to the silicon atom in the silicone molecule is replaced with a hydroxyl group by photoexcitation of the anatase type titanium oxide by irradiation with light including ultraviolet rays, and further thereon. A physisorbed water layer is formed and exhibits a high degree of hydrophilicity. Here, silicone precursors include methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltributoxysilane, ethyltripropoxysilane, phenyl Trimethoxysilane,
Phenyltriethoxysilane, phenyltributoxysilane, phenyltripropoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, dimethyldipropoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldibutoxysilane, diethyldiethyl Propoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylmethyldibutoxysilane, phenylmethyldipropoxysilane, γ-glycidoxypropyltrimethoxysilane, their hydrolysates, and mixtures thereof are preferably used. it can.

In addition, the film coated with the above coating may be adhered to the surface of the substrate with a transparent adhesive such as soap water. Here, a plastic film such as polyethylene terephthalate, polyester, or polyethylene can be suitably used as the film substrate.

[0023]

[Embodiment 1] Anatase type titanium oxide sol (Nissan Chemical, TA-15, solid content 15% by weight, nitric acid peptized type,
pH = 1) 16 parts by weight and silica sol (Nippon Synthetic Rubber,
After mixing 9 parts by weight of Glasca A liquid, solid content 13% by weight, pH = 4, methyltrimethoxysilane (Nippon Synthetic Rubber,
(Glaska B solution) 3 parts by weight and 452 parts by weight of ethanol were added, and the mixture was further stirred for 2 hours, and methyltrimethoxysilane was partially subjected to a hydrolysis reaction and a dehydration condensation polymerization reaction to prepare a coating liquid. This coating solution was subjected to a flow coating method to adjust the surface of a cosmetic inorganic building material (Daiken Kogyo Co., Ltd., Celaster, WK1002-113, ivory white, plate thickness: 4 mm; autoclaved cement calcium silicate plate). After being applied to the surface of the decorative inorganic building material to which the coloring paint was applied, the coating was heated at 150 ° C. for 30 minutes. Next, the surface coated with the coating liquid was irradiated with ultraviolet light for about 3 days at an ultraviolet illuminance of 0.5 mW / cm ² using an ultraviolet light source ((Sankyo Electric Co., Ltd., black light blue (BLB) fluorescent lamp)). For comparison, a # 2 sample of a decorative inorganic building material (Daiken Kogyo, Celaster, WK1002-113, ivory white, plate thickness 4 mm) was also prepared for comparison. The contact angle with water was measured using a contact angle measuring device (Kyowa Interface Science, CA-X150), and the contact angle with water was evaluated 30 seconds after dropping. As a result, the contact angle with water was 90 ° in the sample # 2, indicating a high degree of hydrophilicity, whereas the contact angle with water was 0 ° in the sample # 1.

Next, the # 1 sample and the # 2 sample were installed outdoors, and the self-cleaning property by rainfall was examined.
The self-cleaning property by rainfall was tested as follows. That is, the outdoor dirt acceleration test device shown in FIGS. 3 and 4 was installed on the roof of a building located in Chigasaki City. Referring to FIGS. 3 and 4, the apparatus includes an inclined sample support surface 22 supported on a frame 20 for mounting a sample 24 thereon. A roof 26 inclined forward is fixed to the top of the frame. This roof is made of a corrugated plastic plate, and the collected rain flows down with streaks on the surface of the sample 24 attached to the sample support surface 22. The # 1 sample and the # 2 sample are placed on the sample support surface 22 of this device.
Samples were mounted and exposed to weather conditions for one month from June 12, 1995. During the rainy season, it rained frequently. When observed one month later, there was no photocatalytic coating.
In two samples, vertical streak-like stains were remarkably observed on the sample surface. On the other hand, no stain was observed in the # 1 sample having the photocatalytic film. The state was examined by the color difference change of the most conspicuous part before and after the installation of the acceleration test apparatus. Here, the color difference was examined using a color difference meter (Tokyo Denshoku) according to the Japanese Industrial Standards (JIS) H0201 and using ΔE * display. As a result, in the # 2 sample without the photocatalytic film, the change in color difference was as large as 7.2, and the stain was remarkable.
In the # 1 sample having the photocatalytic coating, the change in color difference was as small as 0.8.

Embodiment 2 FIG. 0.69 g of tetraethoxysilane (Wako Pure Chemical), 1.07 g of anatase type titanium oxide sol (Nissan Chemical Co., TA-15, average particle diameter 10 nm), 29.88 g of ethanol, and 0.36 g of pure water were mixed, and a coating solution was prepared. Was prepared. This coating solution was applied onto a 5 × 10 cm square crystallized glass substrate by a flow coating method. This crystallized glass plate is left
By maintaining the temperature at 50 ° C., tetraethoxysilane was subjected to hydrolysis and dehydration polycondensation to form a coating on the surface of the crystallized glass plate in which anatase-type titanium oxide particles were bound with amorphous silica. The weight ratio of titanium oxide to silica in this coating was 1. After leaving the crystallized glass plate in a dark place for several days, an ultraviolet light source (Sankyo Electric, black light blue (BLB) fluorescent lamp)
The surface of the sample was irradiated with ultraviolet light at an ultraviolet illuminance of 0.5 mW / cm ² for about 1 hour by using, to obtain a # 3 sample. For comparison, a # 4 sample in which a 10 cm square crystallized glass plate was left in a dark place for several days was also prepared. First, water drops were dropped on the # 3 sample and the # 4 sample, the state after the drop was observed, and the contact angle with water was measured. Here, the contact angle with water was evaluated using a contact angle measuring device (Kyowa Interface Science, CA-X150) based on the contact angle with water 30 seconds after dropping. As a result, when a water drop was dropped on the sample surface from the microsyringe in the # 3 sample, it was observed that the water droplet spread uniformly on the sample surface in the form of a water film. Further, the contact angle with water after 30 seconds was highly hydrophilized to about 0 °. On the other hand, in the case of # 4 sample, when a water drop was dropped on the sample surface from the microsyringe, the water droplet adapted to the surface but did not reach a uniform water film state. The contact angle with water after 30 seconds was 30 °.

Next, 1 part by weight of hydrophobic carbon black,
A slurry was prepared by suspending a powder mixture consisting of 1 part by weight of hydrophilic carbon black in water at a concentration of 1.05 g / liter. 150 ml of the slurry was allowed to flow down to the # 1 sample inclined at 45 degrees and dried for 15 minutes, and then 150 ml of distilled water was allowed to flow down and dried for 15 minutes. This cycle was repeated 25 times. The change in color difference before and after the test was measured using a color difference meter (Tokyo Denshoku). The color difference was evaluated according to Japanese Industrial Standards (JIS) H0201 using ΔE * notation. As a result, the color difference change of the # 1 sample before and after the test was 0.
There was almost no change to 6.

Embodiment 3 FIG. Ammonia peptized anatase type titanium oxide sol (Ishihara Sangyo, STS-11) 1g and 2g
Was mixed with 25% aqueous ammonia, and 2 g of distilled water was further added so that the molar ratio of titanium oxide particles to tungstic acid in the coating solution was 10: 1. Next, the above coating solution was applied to a 5 × 10 cm square glazed tile plate (TOTO Koki, AB02E11) and baked at a temperature of 700 ° C. for 30 minutes to form an anatase-type titanium oxide and TiO ₂ / WO ₃ # Five samples were obtained. No color development by the surface layer was observed.
Next, after leaving this # 5 sample in a dark place for several days, BLB
Using a fluorescent lamp, the surface of the sample was irradiated with ultraviolet light at an ultraviolet illuminance of 0.5 mW / cm ² for about 1 hour to obtain a # 6 sample. For comparison, a 5 x 10 cm square glazed tile plate (Tohoku Kikai,
AB7E11) was also prepared in a dark place for several days. First, a water drop was dropped on the # 6 sample and the # 7 sample, and the state after the drop was observed and the contact angle with water was measured. As a result, when a water drop was dropped on the sample surface from the microsyringe of the # 6 sample, it was observed that the water droplet spread uniformly on the sample surface in the form of a water film. Further, the contact angle with water after 30 seconds was highly hydrophilized to about 0 °. On the other hand, in the case of the # 7 sample, when a water droplet was dropped on the sample surface from the micro syringe, the water droplet adapted to the surface, but did not reach a uniform water film state. The contact angle with water after 30 seconds was 30 °. Further, the # 6 sample was left in a dark place for two days thereafter to obtain a # 8 sample. Then, for the # 8 sample, the contact angle with water was similarly measured by a contact angle measuring device. As a result, when a water drop was dropped on the sample surface from the microsyringe on the # 8 sample, it was observed that the water droplet spread uniformly on the sample surface like a # 6 sample.
The contact angle with water was maintained at about 1 °.

Next, oleic acid was applied to the surface of the # 8 sample, and each sample was immersed in water filled in a water tank while keeping the sample surface in a horizontal posture. As a result, the oleic acid was rounded and detached from the surface when lightly rubbed.

Next, 1 part by weight of hydrophobic carbon black,
A slurry was prepared by suspending a powder mixture consisting of 1 part by weight of hydrophilic carbon black in water at a concentration of 1.05 g / liter. 150 ml of the above slurry was allowed to flow down to the # 8 sample inclined at 45 degrees and dried for 15 minutes, and then 150 ml of distilled water was allowed to flow down and dried for 15 minutes. This cycle was repeated 25 times. The change in color difference before and after the test was measured using a color difference meter (Tokyo Denshoku). The color difference was evaluated according to Japanese Industrial Standards (JIS) H0201 using ΔE * notation. As a result, the color difference change of the # 8 sample before and after the test was 0.1.
There was almost no change to 4.

[0030]

According to the present invention, a surface layer containing substantially transparent photocatalytic oxide particles is provided on the surface of a building material for an outer wall, so that the surface of the surface layer becomes hydrophilic in response to photoexcitation of the photocatalyst. Present. Thus, the surface of the surface layer is self-cleaned by rainfall. Furthermore, the surface of the surface layer can be cleaned only by rinsing with water or spraying water.

[Brief description of the drawings]

FIG. 1 is a diagram showing a surface structure of a building material for an outer wall according to the present invention.

FIG. 2 is a diagram showing another surface structure of a building material for an outer wall according to the present invention.

FIG. 3 is a front view of the outdoor dirt acceleration test apparatus according to the embodiment of the present invention.

FIG. 4 is a side view of the outdoor dirt acceleration test apparatus according to the embodiment of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 5/00 C09D 5/00 L

Claims (3)

[Claims] A surface layer containing photocatalytic oxide particles is provided on the surface of a building material substrate for an outer wall, wherein the surface layer forms an amorphous titanium oxide layer on the surface of the substrate, and then crystallizes anatase. It can be produced by baking at the above temperature and causing a phase transition of amorphous titanium oxide to anatase type titanium oxide, and converted to a contact angle with water in response to the photocatalytic oxide particles being photoexcited. And exhibit a hydrophilicity of 10 ° or less, and when the surface of the building material for outer walls is exposed to rainfall, attached sediment or contaminants are washed away by raindrops or easily washed with water. Building materials for exterior walls. 2. The exterior wall building material according to claim 1, wherein the amorphous titanium oxide layer can be formed by an organic titanate method or an electron beam evaporation method. 3. The layer of amorphous titanium oxide is obtained by adding a hydrolysis inhibitor to an organic titanate such as titanium alkoxide, titanium acetate or titanium chelate, diluting the same with a non-aqueous solvent such as alcohol, and then partially hydrolyzing. These are spray-coated, dip-coated,
The building material for an outer wall according to claim 1, wherein the building material can be prepared by applying the composition by a flow coating method, a spin coating method, a roll coating method, or the like, and drying the applied material.