JPH10105887A - Soil-proofing light source cover for traffic signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a difficult-to-soil light source cover for traffic signal by forming a surface layer including photocatalyst grains, silicone and a water- repellent fluororesin on the surface of a base material. SOLUTION: The surface layer including photocatalyst grains, silicone and a water repellent fluororesin is formed on the surface of a base material of the light source cover for traffic light. When light capable of light-exciting photocatalyst is radiated, both of a part in which a hydroxyl group is partially substituted for organic radical obtained by combining a part of silicone exposed to the external air with silicon atoms in a silicone molecule by photocatalyst operation to become hydrophilic, and both of a part where silicone exposed to the external air presents hydrophilicily and a part in which water-repellent fluororesin exposed to the external air presents water repellency are microscopically dispersed on a surface. Because of the structure like this, the hydrophilic stuck material and hydrophobic struck material are not stuck to the surface of the member to keep the surface normal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source cover for an antifouling signal which is hardly contaminated with dust and the like.

[0002]

2. Description of the Related Art A light source cover for a traffic light is contaminated by combustion products in exhaust gas of automobiles, abrasion powder of tires, dust floating in the atmosphere, and the like.

[0003]

If the dark dirt adheres to the light source cover for a traffic light, it becomes difficult to see the red, yellow and blue crossing signals, which impairs traffic safety. Further, since the light source cover for a traffic light is at a high place, the cleaning operation is dangerous and takes time. In view of the above, an object of the present invention is to provide a light source cover for a traffic signal which is hardly stained.

[0004]

According to the present invention, in order to solve the above problems, a surface layer containing photocatalyst particles, silicone and a water-repellent fluororesin is formed on the surface of a light source cover substrate for a traffic light. The present invention provides a light source cover for an antifouling traffic signal characterized by the following. 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 photocatalysis, so that the photocatalyst becomes hydrophilic,
Both the hydrophilic part exposed to the outside air and the water-repellent fluororesin exposed to the outside have a microscopically dispersed structure on the surface. further,
Due to the presence of the photocatalyst, 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 permanently maintains hydrophilicity. The structure in which both the presenting portion and the water-repellent portion 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.

Further, in the present invention, a surface layer containing photocatalyst particles, amorphous silica, and a water-repellent fluororesin is formed on the surface of a light source cover substrate for a traffic light, and the light-repellent cover for a traffic light is characterized in that Provide a light source cover. 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, hydrophilic deposits also
Hydrophobic deposits are not fixed to the member surface, and the surface is maintained in a clean state.

[0006]

Next, a specific surface structure 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 a light source cover for a traffic light. 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 a light source cover substrate for a traffic light. . 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. 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.

The light source cover for a traffic light in the present invention can be used for a light source cover for a road traffic light, a light source cover for a railway traffic light, and the like. Transparent cover plate can be suitably used.

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. The light source used for photoexcitation of the photocatalyst is exposed to sunlight during the day, so that sunlight can be used. Also, at night, road lighting or running vehicle lighting can be used as a light source. In order for the substrate surface to be highly hydrophilic by photoexcitation of the photocatalyst, the illuminance of the excitation light is 0.00
1 mW / cm ² or more is sufficient, but 0.01 mW / cm ^2
It is preferably at least ² and 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 m or less. Then, cloudiness due to irregular reflection of light can be prevented, and the surface layer becomes substantially transparent. further,
More preferably, the thickness of the surface layer is 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.

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 a substrate surface 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 includes a silicone precursor as an essential component 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, and the like. 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. .

[0017] 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 and tetramethoxysilane. It can be produced by dehydration polycondensation with a partial hydrolyzate such as ethoxysilane, tetrapropoxysilane, tetrabutoxysilane, diethoxydimethoxysilane and the like.

As the method for 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.

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 photocatalyst particles and a water-repellent fluororesin as essential components. In addition, a solvent such as water, ethanol, 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.

The silicone precursor used herein has an average composition formula of SiX _q O _{(4-q) / 2} (where X is an alkoxy group or a halogen atom, and q satisfies 0 <q <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, as the coating film forming element comprising the above-mentioned tetrafunctional hydrolyzable silane derivative, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane,
Tetrabutoxysilane, diethoxydimethoxysilane and the like can be suitably used.

Further, the coating film-forming element comprising the above silicate can be produced by partial hydrolysis, dehydration condensation polymerization or the like of the above-mentioned tetrafunctional hydrolyzable silane derivative.

As a method for 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.

[0027]

【Example】

Reference example. Anatase type titanium oxide sol (Nissan Chemical, TA
-15, nitric acid peptizer, pH = 1), silica sol (Nippon Synthetic Rubber, Glasca A solution, pH = 4), methyltrimethoxysilane (Nippon Synthetic Rubber, Glasca B solution) and ethanol, The coating liquid obtained by stirring for about 3 minutes is applied to a 10 cm square soda lime glass substrate by a spray coating method, and heat-treated at 200 ° C. for 15 minutes to obtain 11 parts by weight of anatase type titanium oxide particles and silica 6 A # 1 sample having a surface layer composed of 5 parts by weight of silicone and 5 parts by weight of silicone was obtained. 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, 0.3 mW was applied to the surface of the # 1 sample using an ultraviolet light source (Sankyo Electric, black light blue (BLB) fluorescent lamp).
The sample was irradiated for 1 day with an ultraviolet illuminance of / cm ² to obtain a # 2 sample.
As a result, the contact angle with water of the # 2 sample was hydrophilized to 0 °. Next, a mercury lamp was used for the sample # 1 and the sample # 2 for 22.8.
The sample surface of each of the # 3 samples obtained by irradiating with an ultraviolet illuminance of mW / cm ² for 2 hours was subjected to Raman spectroscopic analysis. as a result,#
The peak of the methyl group observed on the surface of one sample was not observed in 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 photocatalytic anatase-type titanium oxide is replaced with a hydroxyl group by photocatalysis, and is hydrophilized. I understand.

Embodiment. A primer paint (Shin-Etsu Silicone, PC-7A) was applied on a 10 cm square polycarbonate plate by a flow coating method, and then heat-treated at 120 ° C. for 20 minutes to cover the substrate with a primer resin layer. next,
Silicone hard coating agent (Shin-Etsu Silicone,
After applying KP-85) by the flow coating method, 12
Heat treatment was performed at 0 ° C. for 60 minutes to form a hard coat layer.
In addition, the surface is treated with a corona discharge treatment device (Kasuga Electric)
Using a wire electrode as the electrode, a gap of 2 mm between the electrode tip and the sample surface, a voltage of 26 kV, and a frequency of 39 kHz
z, high-frequency corona discharge treatment was performed under the conditions of a sample feeding speed of 4.2 m / min. Next, anatase-type titanium oxide sol (Nissan Chemical Co., TA-15), silica sol (Nippon Synthetic Rubber, Glasca A solution), methyltrimethoxysilane (Nippon Synthetic Rubber, Glasca B solution) and polytetrafluoroethylene (PTFE) particles (Daikin Industries, Lubron L
-5) and ethanol, and a coating solution obtained by stirring for 2 to 3 hours is applied by a spray coating method, and heat-treated at 120 ° C. for 3 hours to obtain 33 parts by weight of anatase type titanium oxide particles, A # 1 sample having a surface layer formed of 66 parts by weight of fluoroethylene particles, 6 parts by weight of silica, and 5 parts by weight of silicone was obtained. The contact angle of the # 1 sample with water was 114 °. Then on the # 1 sample surface
UV light source (Sankyo Electric, Black Light Blue (BL
B) A fluorescent lamp) was used to irradiate with an ultraviolet illuminance of 0.3 mW / cm ² for 1 day to obtain a # 2 sample. As a result, the contact angle of the # 2 sample with water was 99.1 °, 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 # 2 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 # 2 sample and a polycarbonate 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 is shown below the rooftop of the building under the roof.
The sample was set as described above and exposed for 4 months. As a result, stains were observed on the polycarbonate plate, whereas no stains were observed on the # 2 sample.

[0030]

According to the present invention, in a light source cover for a traffic light, a surface layer containing photocatalyst particles, silicone and a water-repellent fluororesin is formed on the surface of the light source cover for a traffic light, or By forming a surface layer containing photocatalyst particles, amorphous silica, and a water-repellent fluororesin on the surface of the light source cover base material for use, hydrophilic attachments and hydrophobic attachments are also applied to the member surface. It will not stick and the surface will be kept clean.

[Brief description of the drawings]

FIG. 1 is a diagram showing a surface structure of a light source cover for a traffic light according to the present invention.

FIG. 2 is a diagram showing another surface structure of the light source cover for a traffic light 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 property, wherein a surface layer containing substantially transparent photocatalytic oxide particles, silicone and a water-repellent fluororesin is formed on the surface of a light source cover substrate for a traffic light. Light source cover for traffic light. 2. A prevention method characterized in that a surface layer containing substantially transparent photocatalytic oxide particles, amorphous silica, and a water-repellent fluororesin is formed on the surface of a light source cover substrate for a traffic light. Light source cover for dirty traffic light.