JPH10102437A - Antifouling traffic sign reflecting board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sign reflecting board from dirt by forming a surface layer containing photocatalystic oxide particles, silicon and water repellent fluororesin on the surface of a road sign reflection board basic material. SOLUTION: Returning reflection glass beads 16 are fixed to a bearing layer 18 through a reflecting film 20 and, at the same time, the beads 16 are covered with a colored clear reflecting board 22 to form a traffic sign reflecting board. Coating composition constituted of photocatalystic oxide such as anatase-type titanium dioxide, etc., precursor of silicon and water repellent fluororesin such as polytetrafluoroethylene, etc., is compounded. Composition constituted of oxide, amorphous silica and fluororesin is compounded. One of two kinds of compositions is applied on the surface of the reflection board, and if desirable, the thickness of a film is less than 0.4μm, and if more desirable, a surface layer 30 less than 0.2μm thick is formed. By the constitution, since hydrophilic adherend and hydrophobic adherend are not made to adhere to the surface of the reflecting board, dirt can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road sign reflector such as a line of sight guide (deliner). More specifically, the present invention relates to a road sign reflecting plate which is hardly adhered to dirt and has excellent night visibility.

[0002]

2. Description of the Related Art A reflector for retroreflecting the light of a vehicle headlight is provided on the shoulder of a road or a guardrail so as to make it easy to recognize the road at night or to guide the driver's line of sight. Has become.

[0003]

According to the report, the most frequently reported opinion in the sign box provided at the prefectural police headquarters is that the visibility of the reflector is not good. . This is considered to be due to the fact that dirt such as combustion products in the exhaust gas, urban dust, and tire abrasion powder adhere to the surface of the reflector and reduce the reflectance of the reflector. In view of the above circumstances, it is an object of the present invention to provide a reflector for a road sign that is not easily 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 road sign reflecting plate base material. An antifouling road sign reflector is provided. 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. Therefore, the light of the headlight is reflected well, and excellent visibility is exhibited.

[0005] In the present invention, a surface layer containing photocatalyst particles, amorphous silica, and a water-repellent fluororesin is formed on the surface of the antifouling road sign reflector base material. Provide a reflector for a dirty road sign. 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.
The surface is kept clean. Therefore, the light of the headlight is reflected well, and excellent visibility is exhibited.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a gaze guide 12 provided with a reflector 10 for a road sign according to the present invention. The reflector 10 is supported by a support 14 fixed to a road or a guardrail.

Referring to FIG. 2, the reflecting plate 10 has a support layer 18 on which retroreflective glass beads 16 having a particle size of, for example, about 50 μm are fixed, and the entire surface of the support layer 18 is a reflection layer formed by aluminum evaporation. Covered by membrane 20. The glass beads 16 are covered with a colored transparent plate 22 made of polycarbonate or the like. In the embodiment shown, the reflector 10 is of the so-called “capsule lens” type, with an air layer 24 between the glass beads 16 and the transparent plate 22. The support layer 18 is fixed to the frame 28 of the visual guide 12 by an adhesive 26.

Next, a specific surface structure of the present invention will be described. In one embodiment of the present invention, as shown in FIG. 3, a photocatalyst particle, silicone,
A surface layer 30 containing a water-repellent fluororesin is formed.
In FIG. 3, when light capable of photoexciting the photocatalyst is irradiated, 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 outside air were both microscopically dispersed on the surface. Structure. Furthermore, the presence of a photocatalyst
Since the amorphous silica permanently maintains hydrophilicity in response to the photoexcitation of the photocatalyst, a structure in which both the hydrophilic portion and the water-repellent portion are microscopically dispersed on the surface 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. Therefore, the light of the headlight is reflected well, and excellent visibility is exhibited.

In another embodiment of the present invention, a surface layer 30 containing photocatalyst particles, amorphous silica, and a water-repellent fluororesin is formed on the surface of a transparent plate 22, as shown in FIG. 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,
Due to the presence of the photocatalyst, the amorphous silica permanently maintains hydrophilicity in response to photoexcitation of the photocatalyst, so that both the hydrophilic portion and the water-repellent portion are microscopically dispersed on the surface. 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. Therefore, the light of the headlight is reflected well, and excellent visibility is exhibited.

[0010] Between the transparent plate 22 and the surface layer 30,
A corrosion-resistant intermediate layer may be provided. As the material of the corrosion-resistant intermediate layer, a silicone resin or the like can be suitably used.

[0011] A photocatalyst is formed by irradiating light (excitation light) having an energy (ie, shorter wavelength) larger than the energy gap between the conduction band and the valence band of the 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 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.

Metals 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 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, or 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. .

[0019] 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 siloxane includes partial hydrolysis and dehydration-condensation polymerization of the hydrolyzable silane derivative, or partial hydrolyzate of the 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 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.

Here, the coating composition contains silica particles or a silica precursor in addition to photocatalyst particles and water-repellent fluororesin as essential components, and in addition, a solvent such as water, ethanol, propanol, hydrochloric acid, nitric acid, and sulfuric acid. , 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, 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 film-forming element composed of the silicate can be prepared by partial hydrolysis, dehydration-condensation polymerization or the like of the tetrafunctional hydrolyzable silane derivative.

As the 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.

[0029]

【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 were mixed. 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.

Example 1. Primer paint (Shin-Etsu Silicone, PC-7A) on a 10 cm square polycarbonate plate
Was applied 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, after applying a silicone hard coating agent (Shin-Etsu Silicone, KP-85) by the flow coating method,
Heat treatment was performed at 120 ° C. for 60 minutes to form a hard coat layer. Further, the surface of the sample was 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.
A high-frequency corona discharge treatment was performed under the conditions of kHz and 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 are mixed, and a coating solution obtained by stirring for 2 to 3 hours is applied by a spray coating method, and is heat-treated at 120 ° C. for 3 hours to give anatase. A # 4 sample having a surface layer composed of 33 parts by weight of titanium oxide particles, 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 114 °. Next, an ultraviolet light source (Sankyo Denki, Black Light Blue (B
(LB) using a fluorescent lamp) and irradiating with an ultraviolet illuminance 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 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 # 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 polycarbonate plate for comparison were placed outdoors, 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 the sample as shown in FIG. 5 under the rooftop of the building and exposing it for 4 months. As a result, some stains were observed on the polycarbonate plate, whereas no stain was observed on the # 5 sample.

[0032]

According to the present invention, in a road sign reflector, a surface layer containing photocatalyst particles, silicone and a water-repellent fluororesin is formed on the surface of the road sign reflector base. Alternatively, by forming a surface layer containing photocatalyst particles, amorphous silica, and a water-repellent fluororesin on the surface of a road sign reflector base material, neither hydrophilic deposits nor hydrophobic deposits are formed. It is not fixed to the member surface, the surface is maintained in a clean state, and excellent visibility is maintained for a long period.

[Brief description of the drawings]

FIG. 1 is a front view of a gaze guidepost provided with a road sign reflector of the present invention.

FIG. 2 is a schematic enlarged sectional view of the reflector shown in FIG.

FIG. 3 is a diagram showing a surface structure of a road sign reflecting plate according to the present invention.

FIG. 4 is a diagram showing another surface structure of the road sign reflecting plate according to the present invention.

FIG. 5 is a view showing a method of setting a test sample according to the embodiment of the present invention.

[Explanation of symbols]

 10: Reflector for road sign 30: Photocatalyst containing layer

Claims (2)

[Claims] 1. An antifouling road sign reflection, characterized in that a surface layer containing photocatalytic oxide particles, silicone and a water-repellent fluororesin is formed on the surface of the road sign reflection plate base material. Board. 2. An antifouling road sign, characterized in that a surface layer containing photocatalytic oxide particles, amorphous silica and a water-repellent fluororesin is formed on the surface of a road sign reflecting plate base material. Reflector.