JP3882625B2 - Sound insulation wall and cleaning method for sound insulation wall - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sound insulation wall of a road or a railway having a coating film whose surface can be cleaned with water.
[0002]
[Prior art]
In the field of construction and paint, contamination of building exterior materials, outdoor buildings and coating films has become a problem with environmental pollution. Dust and particles floating in the atmosphere accumulate on the roof and outer walls of buildings in fine weather. Sediment is washed away by rainwater along with the rain and flows down the outer wall of the building. Furthermore, in the rainy weather, suspended dust is carried by the rain and flows down the outer wall of the building and the surface of the outdoor building. As a result, contaminants adhere to the surface along the rainwater path. As the surface dries, striped stains appear on the surface. The dirt of building exterior materials and coating films consists of combustion products such as carbon black, and inorganic contaminants such as urban dust and clay particles. It is thought that such a variety of pollutants complicates antifouling measures (Yoshinori Tachibana, “Promoting test for contamination of exterior wall finishing materials”, Architectural Institute of Japan, Structured Papers No. 404, October 1989, p. 15-24). Conventional wisdom has been that water-repellent paints such as polytetrafluoroethylene (PTFE) have been considered preferable to prevent dirt on the exterior of the building, but recently, cities that contain a large amount of hydrophobic components. It is considered that the surface of the coating film should be made as hydrophilic as possible against soot and dust (Polymer, Vol. 44, May 1995, p. 307). Therefore, it has been proposed to paint a building with a hydrophilic graft polymer (newspaper "Chemical Industry Daily", January 30, 1995). According to reports, this coating film exhibits a hydrophilicity of 30 to 40 ° in terms of a contact angle with water. However, the contact angle with water of inorganic dust typified by clay minerals is 20 ° to 50 °, and has an affinity for graft polymers with a contact angle with water of 30 to 40 °. It is thought that this graft polymer coating cannot prevent contamination by inorganic dust.
[0003]
[Problems to be solved by the invention]
The object of the present invention is to improve the storage stability to prevent the surface from becoming dirty or to form a coating film that can be cleaned with water by making the surface highly hydrophilic. It is to provide an excellent road or railway sound insulation wall.
[0004]
[Means for Solving the Problems]
The present invention is based on the discovery that in a member in which a surface layer containing a photocatalyst is formed, when the photocatalyst is photoexcited, the surface of the member is highly hydrophilized. This phenomenon is considered to proceed by the mechanism shown below. That is, when the photocatalyst is irradiated with light having energy greater than the energy gap between the upper end of the valence band of the photocatalyst and the lower end of the conduction band, the electrons in the valence band of the photocatalyst are excited to cause conduction electrons and holes to be generated. The polarity is imparted to the surface by the action of either or both of the generated and generated. Thereby, water is chemically adsorbed on the surface, and further, a physical adsorption water layer is formed thereon and increases. Thereby, the surface becomes highly hydrophilic with a water wetting angle of 10 ° or less.
[0005]
The sound insulation wall of the road or railway according to the present invention has a surface covered with a semiconductor photocatalyst-containing layer, and the photocatalyst-containing layer is formed of silicone in which particles of the photocatalyst are dispersed. An organic group bonded to a silicon atom is formed of a silicone derivative that is at least partially substituted with a hydroxyl group by the action of a photocatalyst, and the surface of the layer is made of water as the photocatalyst is photoexcited by sunlight. The contact angle is reduced to 10 ° or less, so that hydrophobic contaminants are prevented from adhering to the surface of the sound insulation wall, or when the sound insulation wall is exposed to rain, dirt adhered to the surface of the sound insulation wall is caused by rainwater. The structure was washed away.
[0006]
The road or railway sound insulation wall according to the present invention is made by coating the surface with a semiconductor photocatalyst-containing layer, the photocatalyst-containing layer is _{TiO 2, ZnO, SnO 2,} SrTiO 3, WO 3, Bi 2 O 3, Fe Including one photocatalyst selected from the group consisting of ₂ O ₃ , the photocatalyst-containing layer further including one metal selected from the group consisting of Pt, Pd, Rh, Ru, Os, Ir, When the photocatalyst is photoexcited by sunlight, the surface of the layer is made hydrophilic, thereby preventing hydrophobic contaminants from adhering to the surface of the sound insulation wall, or when the sound insulation wall is exposed to rain. The dirt attached to the surface of the sound insulation wall is washed away by rainwater.
[0007]
A configuration in which at least a part of the sound insulation wall is made of a transparent material and the photocatalyst containing layer is transparent is conceivable. The photocatalyst containing layer is composed of TiO ₂ , ZnO, SnO ₂ , SrTiO ₃ , WO ₃ , Bi ₂ O ₃ , Fe _2. One type of photocatalyst selected from the group consisting of O ₃ is included, and more specifically, anatase titania can be used.
The photocatalyst-containing layer may further contain one kind of metal selected from the group consisting of Pt, Pd, Rh, Ru, Os, and Ir.
[0008]
Further, the method for cleaning a sound insulation wall of a road or a railway according to the present invention is such that a sound insulation wall covered with a semiconductor photocatalyst containing layer is installed on a side of a road or a railway, and the sound insulation wall is exposed to the sun to expose the sound insulation wall to sunlight. The surface of the layer is hydrophilized by exposing the sound insulation wall to rain, and the dirt adhering to the surface of the layer is washed away with rain water.
[0009]
Another method for cleaning a road or railway sound insulation wall according to the present invention is to install a sound insulation wall covered with a semiconductor photocatalyst containing layer on the side of a road or railway, and to expose the sound insulation wall to solar radiation, thereby photocatalyzing with sunlight. The surface of the layer is hydrophilized by supplying water, and water is supplied to the surface of the layer to wash away contaminants adhering to the surface of the layer.
[0010]
The water is supplied by, for example, injecting water onto a sound insulation wall, and the water is injected from, for example, a traveling work vehicle.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
As a base material applicable as a sound insulation wall for roads or railways according to the present invention, it is a transparent member when antifogging effect is expected, and its material can be suitably used glass, plastic, etc. When the effect is expected, for example, metal, ceramic, glass, plastic, wood, stone, cement, concrete, fiber, fabric, a combination thereof, or a laminate thereof can be suitably used.
[0012]
The surface of the sound insulation wall for road or railway is covered with a semiconductor photocatalyst containing layer, the photocatalyst containing layer is formed of silicone in which particles of photocatalyst are dispersed, and an organic group bonded to silicon atoms of silicone molecules of the photocatalyst containing layer is formed. It is formed of a silicone derivative that is at least partially substituted with a hydroxyl group by the action of a photocatalyst.
[0013]
In the present invention, photocatalytic titanium oxide is valence when irradiated with light (excitation light) having energy (ie, short wavelength) larger than the energy gap between the conduction band and valence band of the crystal. This refers to titanium oxide that can generate conduction electrons and holes due to excitation (photoexcitation) of electrons in the electron band. For example, crystalline titanium oxide such as anatase type titanium oxide and rutile type titanium oxide is preferred. Available. High hydrophilicity in the present invention refers to a state exhibiting water wettability of 10 ° or less, preferably 5 ° or less in terms of contact angle with water.
[0014]
Silicon has an average composition formula RpSiO (4-p) / 2 (wherein R is a functional group composed of one or more monovalent organic groups, or a monovalent organic group and a hydrogen group). A functional group consisting of two or more selected from: X is an alkoxy group or a halogen atom, and p is a number satisfying 0 <p <2. This resin can be obtained by partially hydrolyzing and dehydrating polycondensation of a silicon precursor described later.
[0015]
Here, as a precursor of silicon, an average composition formula RpSiXqO (4-pq) / 2 (wherein R is a functional group composed of one or more monovalent organic groups, or a monovalent It is a functional group composed of two or more selected from an organic group and a hydrogen group, X is an alkoxy group or a halogen atom, and p and q are numbers satisfying 0 <p <2, 0 <q <4 Or a general formula RpSiX4-p (wherein R is a functional group consisting of one or more monovalent organic groups, or a monovalent organic group). A functional group consisting of two or more selected from a group and a hydrogen group, X is an alkoxy group or a halogen atom, and p is 1 or 2. A film forming element can be suitably used.
[0016]
Here, as the coating film forming element comprising the hydrolyzable silane derivative, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxy Silane, ethyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, phenyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, Diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, Nylmethyldipropoxysilane, phenylmethyldibutoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, γ-glycoxydoxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane or the like can be suitably used.
[0017]
In addition, as the film-forming element comprising the siloxane, partial hydrolysis and dehydration condensation polymerization of the hydrolyzable silane derivative, or partial hydrolyzate of the hydrolyzable silane derivative, tetramethoxysilane, tetraethoxysilane, It can be produced by dehydration condensation polymerization with a partial hydrolyzate such as tetrapropoxysilane, tetrabutoxysilane, diethoxydimethoxysilane or the like.
[0018]
The hydrolyzable silane derivative has a general formula RpSiX4-p (wherein R is a functional group composed of one or more monovalent organic groups or a monovalent organic group and a hydrogen group selected from 2). A hydrolyzable silane derivative represented by a functional group comprising at least a species, X is an alkoxy group or a halogen atom, and p is 1 or 2.
[0019]
Here, as the hydrolyzable silane derivative, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane , Phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, phenyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyl Dipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenylmethyldipropoxy Sisilane, phenylmethyldibutoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, γ-glycoxideoxypropyltrimethoxysilane, γ-acryloxy Propyltrimethoxysilane or the like can be suitably used.
[0020]
The siloxane oligomer that coats titanium oxide has an average composition formula RpSiXqO (4-pq) / 2 (wherein R is a functional group composed of one or more monovalent organic groups or a monovalent organic group). A functional group comprising two or more selected from a group and a hydrogen group, X is an alkoxy group or a halogen atom, and p and q are numbers satisfying 0 <p <2, 0 <q <4 A partial hydrolysis and dehydration condensation polymerization of the hydrolyzable silane derivative, or a partial hydrolyzate of the hydrolyzable silane derivative, tetramethoxysilane, tetraethoxysilane, tetra It refers to a dimer to 10-mer of a hydrolyzable silane derivative that can be prepared by dehydration condensation polymerization with a partial hydrolyzate such as propoxysilane, tetrabutoxysilane, diethoxydimethoxysilane and the like.
[0021]
The tetrafunctional hydrolyzable silane derivative covering titanium oxide has a general formula SiX4 (wherein R is a functional group composed of one or more monovalent organic groups, or a monovalent organic group and a hydrogen group). And a functional group consisting of two or more selected from the group consisting of an alkoxy group and a halogen atom.
[0022]
Here, as the tetrafunctional hydrolyzable silane derivative, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, diethoxydimethoxysilane and the like can be suitably used.
[0023]
The silicate oligomer covering titanium oxide has an average composition formula of SiXqO (4-q) / 2 (wherein X is an alkoxy group or a halogen atom, and q is a number satisfying 0 <q <4. And a di- to 10-mer of tetrafunctional hydrolyzable silane that can be prepared by partial hydrolysis and dehydration condensation polymerization of the above tetrafunctional hydrolyzable silane derivative. .
[0024]
Examples of the method for fixing the coating to the titanium oxide particles include spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, and sponge. After coating by a method such as coating, the plate is fixed by a method such as heat treatment.
[0025]
Metals such as Ag, Cu, and Zn can be added to the coating composition. When the metal is added, the surface layer formed by the coating film can kill bacteria and wrinkles attached to the surface even in the dark.
[0026]
A platinum group metal such as Pt, Pd, Ru, Rh, Ir, and Os can be added to the coating composition. When the metal is added, the surface layer formed by the coating film can enhance the redox activity of the photocatalyst, and can improve the degradability of organic contaminants and the decomposability of harmful gases and odors.
[0027]
In addition, the coating composition includes a catalyst that promotes hydrolysis of a solvent such as water, ethanol, and / or a precursor of silicone such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid, and maleic acid, Catalysts for curing the precursors of silicon such as basic compounds such as tributylamine and hexylamine, acidic compounds such as aluminum triisopropoxide and tetraisopropyl titanate, and copolymers such as silane coupling agents. -You may add surfactant etc. which improve the dispersibility of a ting liquid.
[0028]
Basically, the coating composition is applied by coating the coating composition on the wall surface of a sound insulation wall of a road or railway and curing it to form a coating film.
[0029]
Examples of the coating composition coating method include spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, and sponge coating. The method can be suitably used. As the curing method, polymerization can be performed by heat treatment, standing at room temperature, irradiation with ultraviolet rays, or the like.
[0030]
When a coating film is formed on the sound insulation wall surface by the above method, the wall surface becomes hydrophilic in response to photoexcitation of the photocatalyst. Here, in order for the substrate surface to be highly hydrophilic by photoexcitation of the photocatalyst, the illuminance of the excitation light may be 0.001 mW / cm 2 or more, preferably 0.01 mW / cm 2 or more. More preferably, it is 1 mW / cm 2 or more. As the light source used for photoexcitation of the photocatalyst, sunlight, indoor lighting, fluorescent lamp, mercury lamp, incandescent lamp, xenon lamp, high-pressure sodium lamp, metal halide lamp, BLB lamp and the like can be suitably used.
[0031]
The film thickness of the surface layer formed by the coating on the sound insulating wall surface is preferably 0.4 μm or less. By doing so, white turbidity due to irregular reflection of light can be prevented, and the surface layer becomes substantially transparent. Furthermore, it is more preferable that the film thickness of the surface layer is 0.2 μm or less. By doing so, coloration of the surface layer due to light interference can be prevented. Further, the thinner the surface layer, the higher the transparency. Furthermore, if the film thickness is reduced, the wear resistance of the surface layer is improved.
[0032]
【The invention's effect】
According to the sound insulation wall of the road or railway according to the present invention, the surface of the sound insulation wall is converted to a contact angle with water of 10 ° or less, so that condensed water can be used even if moisture or steam in the air is condensed. However, the tendency of forming a uniform water film without forming individual water droplets becomes remarkable. Therefore, the tendency not to cause light scattering haze on the surface becomes remarkable.
Similarly, if the sound insulation wall surface is in a state of 10 ° or less, preferably 5 ° or less in terms of contact angle with water, carbon black contained in exhaust gas from urban dust, automobiles, etc. Hydrophobic pollutants such as combustion products, fats and oils, sealant elution components, and inorganic clay pollutants are difficult to adhere, and even if they adhere, they can be easily removed by rainfall or water washing.
[0027]
Furthermore, the surface of the wall surface exhibits the above-mentioned high degree of hydrophilicity and maintains this state, so that in addition to the antifogging effect and the surface cleaning effect, the antistatic effect (dust adhesion preventing effect), the heat insulating effect, and the bubbles in water Adhesion prevention effect, efficiency improvement effect in heat exchanger, biocompatibility improvement effect, etc. come to be exhibited.

Claims (6)

The surface of the sound insulation wall of a road or railway is covered with a semiconductor photocatalyst containing layer,
The photocatalyst-containing layer is formed of silicone in which photocatalyst particles are dispersed,
The organic group bonded to the silicon atom of the silicone molecule of the photocatalyst containing layer is formed of a silicone derivative that is at least partially substituted with a hydroxyl group by the action of the photocatalyst,
As the photocatalyst is photoexcited by sunlight, the surface of the layer is hydrophilized so that the contact angle with water is 10 ° or less ,
This prevents hydrophobic contaminants from adhering to the surface of the sound insulation wall,
Alternatively, the sound insulation wall of a road or railway, wherein dirt attached to the surface of the sound insulation wall is washed away by rain water when the sound insulation wall is exposed to rain. The sound insulating wall according to claim 1 , wherein the photocatalyst-containing layer contains titanium oxide . The sound insulation wall according to claim 2 , wherein the photocatalyst is anatase type titania. The sound insulation wall according to claim 2 or 3 , wherein the photocatalyst-containing layer further contains one kind of metal selected from the group consisting of Pt, Pd, Rh, Ru, Os, and Ir. Install a sound insulation wall covered with a semiconductor photocatalyst containing layer on the side of a road or railway,
Exposing a photocatalyst by sunlight by exposing the sound insulation wall to solar radiation to make the surface of the layer hydrophilic with a water contact angle of 10 ° or less ,
A method of cleaning a sound insulation wall of a road or a railway, wherein the sound insulation wall is exposed to rain to wash away dirt adhering to the surface of the layer with rain water. A sound insulation wall covered with a semiconductor photocatalyst-containing layer is installed on the side of a road or railway, and the sound insulation wall is exposed to the sun to excite the photocatalyst by sunlight so that the surface of the layer has a contact angle with water of 10 Hydrophilize below ° ,
A method for cleaning a sound insulation wall of a road or a railway, comprising washing away contaminants adhering to the surface of the layer by supplying water to the surface of the layer.