JPH10102994A - Stain preventive tunnel inner wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a tunnel inner wall hard to be stained without adhering a sticking material by forming a surface layer containing photocatalyst particles, slicone and a water repellent fluroresin on a base material surface of a tunnel inner wall. SOLUTION: A surface layer containing photocatalyst particles such as a titanium oxide and a zinc oxide, silicone and a water repellent fluororesin, is formed on a surface of a tunnel wall base material. When the exciting light is irradiated to the surface layer, an organic group bonded to a silicon atom of a part of slicone exposed to outside air, is partially substituted with a hydoxyl group, and a hydrophilic property is presented. Both of this hydrophilic part and an exposed part of the water repellent fluororesin are formed as a structure microscopically dispersed on a surface. When the surface is formed in such a structure, both a hydrophilic sticking material and a hydrophobic sticking material do not adhere to a surface, and it can be maintained in a clean condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antifouling tunnel inner wall which is hardly contaminated with smoke or the like.

[0002]

2. Description of the Related Art The inner wall of a road tunnel is sometimes formed only by cast-in-place concrete. In recent years, however, in order to improve the environment in the tunnel, especially the scenery, and prevent traffic accidents in the tunnel, They are often painted or lined with interior boards (lining). As interior panels, asbestos panels, tiles, enameled iron plates, plated iron plates, stainless steel plates, aluminum panels, plastic panels, and the like are used.

[0003]

The inner wall of the tunnel is contaminated with soot in the exhaust gas of automobiles, abrasion powder of tires, and dust soaring from the road surface. In particular, highway tunnels with heavy traffic are heavily soiled. On a highway, the length of a tunnel tends to be long, and if ventilation is insufficient, the tunnel is apt to become dirty. If the inner wall of the tunnel becomes dirty with smoke, etc., the landscape of the tunnel will be damaged,
The dark impression can make driving in the tunnel painful or adversely affect the driver's attention. Therefore, it is desirable to clean the inner wall of the tunnel as needed.

Conventionally, the inner wall of a tunnel has been cleaned by brush cleaning. Cleaning the inner wall requires traffic regulation (such as lane restriction), which impedes smooth traffic and involves considerable danger. Therefore, it is difficult to wash it with sufficient frequency. In addition, washing the inner wall of the tunnel requires a long-term traffic regulation, which is dangerous. Further, since an interior plate such as an asbestos panel has irregularities on its surface, it is not only easy to stain, but it is impossible to completely remove the stain by brush cleaning. Some of the adhered dirt remains even after brush cleaning, so that the dirt accumulates as the number of times of cleaning increases.
In view of the above circumstances, an object of the present invention is to provide an inner wall of a tunnel that is not easily stained.

[0005]

In order to solve the above-mentioned problems, the present invention is characterized in that a surface layer containing photocatalyst particles, silicone and a water-repellent fluororesin is formed on a substrate surface. Provide an antifouling tunnel inner wall. With such a configuration, when the photocatalyst is photoexcited, the organic group bonded to the silicon atom in the silicone molecule is at least partially replaced by a hydroxyl group by the photocatalytic action, so that the silicone becomes hydrophilic. Both the hydrophilic part exposed to the outside air and the water-repellent part exposed to the outside air are microscopically dispersed on the surface. Furthermore, the presence of the photocatalyst allows the silicone in which the organic group bonded to the silicon atom in the silicone molecule is at least partially substituted with a hydroxyl group in response to the photoexcitation of the photocatalyst to remain permanently hydrophilic. The structure in which both the portion exhibiting the property and the portion exhibiting the water repellency are microscopically dispersed on the surface is maintained. In such a structure, since the hydrophilic surface and the water-repellent surface are adjacent to each other, the hydrophilic adherent that easily adapts to the hydrophilic surface does not adapt to the adjacent water-repellent portion. Conversely, hydrophobic deposits that are easily adapted to the water-repellent surface do not adapt to adjacent hydrophilic portions. Therefore, neither the hydrophilic deposit nor the hydrophobic deposit is fixed to the member surface, and the surface is maintained in a clean state.

The present invention also provides an antifouling tunnel inner wall, characterized in that a surface layer containing photocatalyst particles, amorphous silica and a water-repellent fluororesin is formed on the surface of a substrate. With this configuration, both the amorphous silica in the surface layer and the water-repellent portion where the water-repellent fluororesin is exposed to the outside are exposed on the surface. It becomes the structure distributed in.
Further, the presence of the photocatalyst allows the amorphous silica to maintain its hydrophilicity permanently in response to the photoexcitation of the photocatalyst, so that both the hydrophilic portion and the water-repellent portion are microscopically visible on the surface. The distributed structure is maintained. In such a structure, since the hydrophilic surface and the water-repellent surface are adjacent to each other, the hydrophilic adherent that easily adapts to the hydrophilic surface does not adapt to the adjacent water-repellent portion. Conversely, hydrophobic deposits that are easily adapted to the water-repellent surface do not adapt to adjacent hydrophilic portions. Therefore, neither the hydrophilic deposit nor the hydrophobic deposit is fixed to the member surface, and the surface is maintained in a clean state.

[0007]

Next, a specific configuration of the present invention will be described. In one embodiment of the present invention, as shown in FIG. 1, a surface layer containing photocatalyst particles, silicone, and a water-repellent fluororesin is formed on the surface of the tunnel inner wall substrate. When light capable of photo-exciting the photocatalyst is irradiated to FIG. 1, at least a part of the silicone exposed to the outside air becomes at least partially converted into a hydroxyl group by an organic group bonded to a silicon atom in the silicone molecule by a photocatalytic action. As a result of the substitution, it became hydrophilic, and both the silicone-exposed hydrophilic part exposed to the outside air and the water-repellent fluororesin exposed to the air and the water-repellent part were microscopically dispersed on the surface. Structure. Further, the presence of the photocatalyst allows the amorphous silica to maintain its hydrophilicity permanently in response to the photoexcitation of the photocatalyst, so that both the hydrophilic portion and the water-repellent portion are microscopically visible on the surface. The distributed structure is maintained. With such a structure, neither the hydrophilic deposit nor the hydrophobic deposit is fixed to the member surface, and the surface is maintained in a clean state.

In another embodiment of the present invention, as shown in FIG. 2, a surface layer containing photocatalyst particles, amorphous silica, and a water-repellent fluororesin is formed on the surface of the tunnel inner wall substrate. With such a configuration, the amorphous silica in the surface layer is exposed to the outside air and exhibits a hydrophilic portion,
Both of the water-repellent portions of the water-repellent fluororesin exposed to the outside air are microscopically dispersed on the surface. Further, the presence of the photocatalyst allows the amorphous silica to maintain its hydrophilicity permanently in response to the photoexcitation of the photocatalyst, so that both the hydrophilic portion and the water-repellent portion are microscopically visible on the surface. The distributed structure is maintained. With such a structure, neither the hydrophilic deposit nor the hydrophobic deposit is fixed to the member surface, and the surface is maintained in a clean state.

A photocatalyst is a device that emits light (excitation light) having an energy (ie, shorter wavelength) larger than the energy gap between the conduction band and the valence band of a crystal when the electrons in the valence band are irradiated. A substance capable of generating conduction electrons and holes by excitation (photoexcitation). Photocatalytic oxides include, for example, anatase-type titanium oxide, rutile-type titanium oxide, zinc oxide, tin oxide, and ferric oxide. And oxides such as bismuth trioxide, tungsten trioxide and strontium titanate. As a light source used for photoexcitation of the photocatalyst, illumination in a tunnel such as a high-pressure sodium lamp, a low-pressure sodium lamp, a metal halide lamp, a fluorescent lamp, a mercury lamp, a fluorescent mercury lamp, and a vehicle light passing through a headlamp can be used. In order for the surface of the base material to be highly hydrophilized by photoexcitation of the photocatalyst, the illuminance of the excitation light may be 0.001 mW / cm ² or more.
It is preferably at least W / cm ^2, more preferably at least 0.1 mW / cm ² .

The silicone has an average composition formula R _p SiO _{(4-p) / 2} (where R is a functional group comprising one or more monovalent organic groups, or a monovalent organic group) Wherein X is an alkoxy group or a halogen atom, and p is a number satisfying 0 <p <2). it can.

As the water-repellent fluororesin, polytetrafluoroethylene, polychlorotrifluoroethylene, polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer and the like can be suitably used.

The thickness of the surface layer is preferably set to 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 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.

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.

Pt, Pd, Ru, Rh, I
A platinum group metal such as r or Os can be added.
The surface layer to which the metal is added can enhance the redox activity of the photocatalyst, and can improve the decomposability of organic contaminants and the decomposability of harmful gases and odors.

The present invention can be applied to both a cast-in-place concrete substrate, an asbestos panel, a tile, an enameled iron plate, a plated iron plate, a stainless steel plate, an aluminum panel, a plastic panel and other interior plate substrates as a tunnel inner wall substrate. is there.

Next, a method for producing an antifouling member in which a surface layer containing photocatalytic oxide particles, silicone and a water-repellent fluororesin is formed on the surface of a substrate will be described. The production method in this case is basically based on applying a coating composition to the surface of a substrate and curing the composition.

Here, the coating composition contains, as essential components, a silicone precursor in addition to the photocatalyst particles and the water-repellent fluororesin, and a solvent such as water, ethanol, propanol, hydrochloric acid, nitric acid, sulfuric acid, acetic acid, Catalysts that promote the hydrolysis of silicone precursors such as maleic acid, and basic compounds such as tributylamine and hexylamine,
A catalyst for curing a silicone precursor such as acidic compounds such as aluminum triisopropoxide and tetraisopropyl titanate, and a surfactant for improving dispersibility of a coating solution such as a silane coupling agent may be added. .

[0018] Here, as the precursor of a silicone, in the average composition formula _{R p SiX q O (4-} p-q) / 2 ( wherein, R consists of one or more organic groups monovalent functional X or a functional group comprising two or more selected from a monovalent organic group and a hydrogen group, X is an alkoxy group or a halogen atom, and p and q are 0 <p <2, 0 <
q <film forming element comprising a siloxane represented by 4 is a number satisfying), or the general formula R p _SiX 4-p _(wherein, R is from one or more of the monovalent organic group Or a functional group consisting of two or more selected from a monovalent organic group and a hydrogen group, wherein X is an alkoxy group,
Alternatively, a film-forming element composed of a hydrolyzable silane derivative represented by a halogen atom and p is 1 or 2) can be suitably used.

Here, as the coating film forming element comprising the hydrolyzable silane derivative, methyltrimethoxysilane,
Methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, Phenyltributoxysilane,
Dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, phenyl Methyldipropoxysilane, phenylmethyldibutoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, γ-glycoxydoxypropyltrimethoxysilane, γ -Acryloxypropyltrimethoxysilane and the like can be suitably used.

The film-forming element composed of the above-mentioned siloxane includes partial hydrolysis and dehydration-condensation polymerization of the above-mentioned hydrolyzable silane derivative, or partially hydrolyzate of the above-mentioned hydrolyzable silane derivative, tetramethoxysilane, tetramethoxysilane and tetramethoxysilane. It can be produced by dehydration polycondensation with a partial hydrolyzate such as ethoxysilane, tetrapropoxysilane, tetrabutoxysilane, diethoxydimethoxysilane and the like.

As a method of applying the above coating composition, methods such as spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, and sponge coating can be suitably used. As a curing method, it can be carried out by polymerizing by heat treatment, standing at room temperature, ultraviolet irradiation, or the like.

Next, a method for producing an antifouling member in which a surface layer containing photocatalyst particles, amorphous silica and a water-repellent fluororesin is formed on the surface of a substrate will be described. The production method in this case is basically based on applying a coating composition to the surface of a substrate and curing the composition.

The coating composition contains silica particles or a silica precursor in addition to the photocatalyst particles and the water-repellent fluororesin as essential components. In addition, solvents such as water, ethanol and propanol, hydrochloric acid, nitric acid and sulfuric acid are used. , Acetic acid, catalysts that promote the hydrolysis of silica precursors such as maleic acid, and silica such as basic compounds such as tributylamine and hexylamine, and acidic compounds such as aluminum triisopropoxide and tetraisopropyl titanate. A catalyst for curing the precursor or a surfactant for improving the dispersibility of the coating liquid such as a silane coupling agent may be added.

[0024] As the precursor wherein the silicone in the average composition formula _{SiX q O (4-q)} / 2 ( wherein, X is an alkoxy group or a halogen atom, q is 0 <q <satisfies 4 A film-forming element composed of a silicate represented by the following formula: or a general formula SiX ₄ (wherein R is a functional group composed of one or more monovalent organic groups, or a monovalent organic group) Is a functional group consisting of two or more selected from an organic group and a hydrogen group, wherein X is an alkoxy group,
Alternatively, a film-forming element made of a tetrafunctional hydrolyzable silane derivative represented by a halogen atom) can be suitably used.

Here, the coating film forming element comprising the above-mentioned tetrafunctional hydrolyzable silane derivative includes tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane,
Tetrabutoxysilane, diethoxydimethoxysilane and the like can be suitably used.

The coating film-forming element comprising the above silicate can be prepared by partial hydrolysis, dehydration condensation polymerization, etc. of the above-mentioned tetrafunctional hydrolyzable silane derivative.

As the method of applying the coating composition, methods such as spray coating, dip coating, flow coating, spin coating, roll coating, brush coating, and sponge coating can be suitably used. As a curing method, it can be carried out by polymerizing by heat treatment, standing at room temperature, ultraviolet irradiation, or the like.

[0028]

【Example】

Reference example. Anatase type titanium oxide sol (Nissan Chemical, TA
-15, nitric acid peptizing type, pH = 1), silica sol (Nippon Synthetic Rubber, Glasca A solution, pH = 4), methyltrimethoxysilane (Nippon Synthetic Rubber, Glasca B solution) and ethanol, and The coating liquid obtained by stirring for about 3 minutes is applied onto a 5 × 10 cm square glazed tile base material (TOTO Koki, AB02E11) by a spray coating method,
Heat treatment was performed at 200 ° C. for 15 minutes to obtain a # 1 sample having a surface layer formed of 11 parts by weight of anatase type titanium oxide particles, 6 parts by weight of silica, and 5 parts by weight of silicone. The contact angle of the # 1 sample with water was 85 °. Here, the contact angle with water was evaluated using a contact angle measuring device (Kyowa Interface Science, CA-X150) by the contact angle with water 30 seconds after a water droplet was dropped from the micro syringe. Next, the surface of the # 1 sample was irradiated with ultraviolet light of 0.3 mW / cm ² for one day using an ultraviolet light source (Sankyo Electric, black light blue (BLB) fluorescent lamp) to obtain a # 2 sample. As a result, the contact angle with water of the # 2 sample was hydrophilized to 0 °. Next, # 1 sample and #
A sample surface of each of # 3 samples obtained by irradiating one sample with a mercury lamp at 22.8 mW / cm ² of ultraviolet illuminance for 2 hours was subjected to Raman spectroscopic analysis. As a result, the methyl group peak observed on the # 1 sample surface was not observed on the # 3 sample, but a broad peak of the hydroxyl group was observed instead. From the above,
The organic group bonded to the silicon atom in the silicone molecule on the surface of the coating in response to the photoexcitation of the anatase-type titanium oxide as a photocatalyst is replaced with a hydroxyl group by photocatalysis,
It can be seen that the surface is made hydrophilic.

Embodiment 1 Anatase type titanium oxide sol (Nissan Chemical, TA-15) and silica sol (Nippon Synthetic Rubber,
(Glaska A solution), methyltrimethoxysilane (Nippon Synthetic Rubber, Glaska B solution), polytetrafluoroethylene (PTFE) particles (Daikin Industries, Lubron L-5) and ethanol are mixed and stirred for 2-3 minutes. The obtained coating solution is applied onto a 5 × 10 cm square glazed tile base material (TOTO Koki, AB02E11) by a spray coating method, and heat-treated at 200 ° C. for 15 minutes to obtain 33 parts by weight of anatase type titanium oxide particles. A # 4 sample having a surface layer composed of 66 parts by weight of polytetrafluoroethylene particles, 6 parts by weight of silica, and 5 parts by weight of silicone was obtained. The contact angle of the # 4 sample with water was 110 °. Then, on the surface of # 4 sample,
UV light source (Sankyo Electric, Black Light Blue (BL
B) Using a fluorescent lamp), the sample was irradiated with ultraviolet light of 0.3 mW / cm ² for 1 day to obtain a # 5 sample. As a result, the contact angle of the # 5 sample with water was 97.4 °, and did not change much. According to the above reference example, the portion where the silicone is exposed to the outside air is supposed to be replaced by a hydroxyl group by a photocatalytic action and the organic group bonded to the silicon atom in the silicone molecule to be hydrophilized. It is considered that the contact angle with the film slightly decreased. In other words, the surface of the # 5 sample has both a hydrophilic portion where the hydroxyl group is substituted by the photocatalytic action and the hydrophilicized silicone is exposed to the outside air and a water-repellent portion where the water-repellent fluororesin is exposed to the outside air. It is assumed that the structure is microscopically dispersed on the surface.

Next, the # 5 sample and a glazed tile plate were placed outdoors for comparison, and the cleanliness of the surface against deposits and contaminants was examined. The cleanliness of the surface against sediments and contaminants was determined by placing a sample as shown in FIG. 3 under a covered part on the roof of a building and exposing it for four months. As a result, some stains were observed on the glazed tile plate, whereas no stain was observed on the # 5 sample. The state was examined by the change in color difference before and after exposure for 4 months. Here, the color difference is measured using a color difference meter (Tokyo Denshoku) and measured according to Japanese Industrial Standards (JIS) H
In accordance with No. 0201, a check was made using the ΔE * designation. As a result, the change in color difference before and after exposure was 2 in the glazed tile plate, whereas it was as small as 0.5 in the # 5 sample.

[0031]

According to the present invention, on the inner wall of the tunnel, a surface layer containing photocatalyst particles, silicone and a water-repellent fluororesin is formed on the substrate surface, or the photocatalyst particles are formed on the substrate surface. By forming a surface layer containing silica and amorphous silica and a water-repellent fluororesin, neither hydrophilic deposits nor hydrophobic deposits are fixed to the member surface, and the surface is cleaned. State is maintained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a surface structure of an inner wall of a tunnel according to the present invention.

FIG. 2 is a diagram showing another surface structure of the inner wall of the tunnel according to the present invention.

FIG. 3 is a diagram showing a method of setting a test sample according to the embodiment of the present invention.

Claims (2)

[Claims] 1. An antifouling tunnel inner wall, wherein a surface layer containing photocatalytic oxide particles, silicone and a water-repellent fluororesin is formed on the surface of a substrate. 2. An antifouling tunnel inner wall, wherein a surface layer containing photocatalytic oxide particles, amorphous silica, and a water-repellent fluororesin is formed on a surface of a base material.