JPH09231819A - Cleaning methods and antifouling methods for tunnel and road lighting devices - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a method for cleaning a cover glass of a lighting device for a tunnel or a road, which can be carried out without traffic regulation or with minimal traffic regulation. [Structure] The surface of a cover glass (18) of a tunnel or road lighting device (10) is covered with a photocatalyst layer (20), and the photocatalyst is photoexcited by light from a light source (16) or sunlight. The surface of the photocatalyst layer (20) is made superhydrophilic by photoexcitation, and the adhesion of combustion products is prevented. If necessary, water can be sprayed from the work vehicle onto the cover glass (18) to easily wash away the attached contaminants.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a cover glass of a lighting device for a tunnel or a road and a method for preventing soiling.

[0002]

2. Description of the Related Art The cover glass of a lighting device for tunnels and roads is contaminated by combustion products in the exhaust gas and dust soared from the road surface. The light output of the lighting device decreases with the contamination. Therefore, the cover glass must be cleaned regularly or as needed.

[0003]

The cleaning of tunnels and road lighting devices often requires traffic regulation, which hinders smooth road traffic. In particular, in a tunnel, it is not only difficult to regulate traffic for cleaning the lighting device, but it is also very dangerous, and therefore cleaning cannot be performed with sufficient frequency. Also, cleaning is a high place work,
Since it takes time to work, the time for traffic regulation tends to be long.

It is an object of the present invention to provide a method for cleaning cover glass of a tunnel or a road lighting device which can be carried out without substantially restricting traffic or with minimum traffic restriction. is there. Another object of the present invention is to
It is an object of the present invention to provide a method capable of preventing the cover glass of a tunnel or road lighting device from being soiled.

[0005]

The present inventors have discovered that photoexcitation of a photocatalyst makes the surface of the photocatalyst highly hydrophilic. Surprisingly, when photocatalytic titania was photoexcited with ultraviolet light, the surface was highly hydrophilicized so that the contact angle with water was 10 ° or less, more specifically 5 ° or less, and especially about 0 °. Was discovered.

The present invention is based on such a discovery. According to the present invention, the surface of the cover glass of a lighting device for a tunnel or a road is coated with a transparent layer containing a semiconductor photocatalyst, and the photocatalyst layer is photoexcited by photoexciting the photocatalyst. The surface of is made hydrophilic. It is difficult for hydrophobic substances such as combustion products in exhaust gas to adhere to the surface thus hydrophilized. Also,
When water is supplied to the surface of the photocatalyst layer as needed, the contaminants attached to the surface are easily washed away by the water.

[0007] Preferably, the photoexcitation of the photocatalyst is performed by the light emitted from the illuminating device itself. In a preferred embodiment, the cleaning is done by spraying water onto the cover glass, preferably from a moving work vehicle. The above features and effects of the present invention, as well as other features and advantages, will be apparent from the description of the following embodiments.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the case of a tunnel lighting device, the lighting device can be an embedded type or a direct mounting type depending on the tunnel structure. In the example shown in FIG. 1, the lighting device 10 is of a recessed type and has a housing 14 buried in a concrete wall 12 of the tunnel. The light source 16 is covered by a cover glass 18. As the light source 16, a low-pressure sodium lamp, a high-pressure sodium lamp, a fluorescent lamp, a mercury lamp, a fluorescent mercury lamp, and other electric lamps can be used.

According to the invention, the surface of the cover glass 18 is coated with a transparent layer 20 containing a photocatalyst, which is photoexcited by the light emitted by the light source 16. Upon photoexcitation, the surface of the photocatalyst layer 20 is made hydrophilic so that the contact angle with water is 10 ° or less, particularly about 0 °.

Photocatalysts include TiO ₂ , ZnO, SnO ₂ and SrTiO ₂ .
₃ , WO ₃ , Bi ₂ O ₃ , Fe ₂ O ₃ , CdTe, MoS ₂ , CdS, or a mixture thereof can be used, and depending on the kind of the light source 16, it is photoexcited by the light from the light source. One with bandgap energy can be selected. For example, when the light source 16 is a low pressure sodium lamp with a wavelength of 589 nm, CdTe or MoS ₂ can be used. Light source 1
When 6 contains ultraviolet rays with a wavelength of 413 nm or less, rutile type TiO
₂ , anatase type when it contains ultraviolet rays with a wavelength of 387 nm or less
TiO ₂ or ZnO, Sn if it contains UV light with a wavelength of 344 nm or less
Preference is given to using O ₂ .

The thickness of the photocatalyst layer 20 is preferably 0.2 μm or less. In this case, sufficient transparency can be ensured, and coloring due to light interference can be prevented.

The photocatalyst layer 20 can be formed by applying a sol containing photocatalyst particles to the cover glass 18 and sintering it at a temperature below the softening point of the glass. In this case, in order to prevent alkaline network modifying ions such as sodium in the glass from diffusing from the glass into the photocatalyst layer, the surface of the cover glass 18 should be previously coated with an intermediate layer such as silica. preferable. In addition, the photocatalyst is Ti
In the case of O ₂ , it is preferable that the photocatalyst layer 20 contains SiO ₂ or SnO ₂ . By doing so, the surface of the photocatalyst layer 20 can be made superhydrophilic so that the contact angle with water upon photoexcitation becomes 0 °.

Alternatively, the photocatalyst layer 20 is formed by forming a thin film of an amorphous photocatalyst precursor on the surface of the cover glass 18 and heating the amorphous thin film to crystallize it to convert it into a photoactive photocatalyst. You may. For example, the photocatalyst is Ti
In the case of O ₂ , a thin film of amorphous titania is formed on the surface of the cover glass 18, and then the amorphous titania is crystallized (anatase or rutile by firing at a temperature of 400 ° C. or higher and the softening point of the glass or lower). ) Can be phase-changed. The photocatalyst layer 20 formed in this way is
When photoexcited, it becomes superhydrophilic to the extent that the contact angle with water becomes 0 °.

Amorphous titania is obtained by adding a hydrolysis inhibitor such as hydrochloric acid or ethylamine to a titanium alkoxide (eg, tetraethoxy titanium, tetraisopropoxy titanium, tetra n-propoxy titanium, tetrabutoxy titanium, tetramethoxy titanium). Then, after diluting with an alcohol such as ethanol or propanol, the mixture is spray-coated, flow-coated, spin-coated, dip-coated, with partial or complete hydrolysis.
It can be formed by applying it to the surface of the cover glass 18 by roll coating or another coating method and drying at a temperature of normal temperature to 200 ° C. By drying, hydrolysis of the alkoxide of titanium is completed to produce titanium hydroxide, and a layer of amorphous titania is formed on the surface of the substrate by dehydration-condensation polymerization of titanium hydroxide. Instead of titanium alkoxides, other organic titanium compounds such as titanium chelates or titanium acetate may be used.

Alternatively, the amorphous titania may be obtained by spray coating, flow coating, spin coating, dip coating or roll coating an acidic aqueous solution of an inorganic titanium compound such as TiCl ₄ or Ti (SO ₄ ) _{2 on} the surface of the cover glass 18. Can be formed by subjecting the inorganic titanium compound to hydrolysis and dehydration polycondensation by drying the inorganic titanium compound at a temperature of about 100 to 200 ° C.

Another preferred method of forming the photocatalyst layer 20 that exhibits superhydrophilicity such that the contact angle with water upon photoexcitation is 0 ° is uncured or partially cured silicone (organopolysiloxane) or A coating composition comprising photocatalyst particles dispersed in a coating film forming element composed of a silicone precursor. When this coating composition is applied to the surface of the cover glass 18 and the coating film-forming element is cured and then the photocatalyst is photoexcited, the organic group bonded to the silicon atom of the silicone molecule is replaced with the hydroxyl group by the photocatalytic action of the photocatalyst. The surface of the photocatalyst layer 20 is made superhydrophilic.

The coating film-forming element of this coating composition includes methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, and methyltri-t-silane.
-Butoxysilane; ethyltrichlorosilane, ethyltribromosilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane,
Ethyltri-t-butoxysilane; n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltriisopropoxysilane, n-propyltrit-butoxysilane; n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-hexyltriisopropoxysilane, n-hexyltrit-butoxysilane; n-decyltrichlorosilane, n -Decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyltriisopropoxysilane, n-decyltrit-butoxysilane; n-octadecyltrichlorosilane, n
-Octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n-
Octadecyltri-t-butoxysilane; phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltri-t-butoxysilane; tetrachlorosilane, tetrabromosilane,
Tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane; dimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane, dimethyldiethoxysilane; diphenyldichlorosilane, diphenyldibromosilane, diphenyldimethoxysilane, Diphenyldiethoxysilane; phenylmethyldichlorosilane, phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane; trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, triisopropoxyhydrosilane, tri-t -Butoxyhydrosilane; vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyl Triethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane; trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane. , Trifluoropropyltri-t-butoxysilane;
γ-glycidoxypropylmethyldimethoxysilane, γ
-Glycidoxypropylmethyldiethoxysilane, γ-
Glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri-t-butoxysilane; γ-methacryloxypropylmethyldimethoxysilane Γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxypropyltri t-butoxysilane; γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ
-Aminopropyltriisopropoxysilane, γ-aminopropyltri-t-butoxysilane; γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane Γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-butoxysilane; β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane; And their partial hydrolysates; and mixtures thereof.

The photocatalyst layer 20 thus formed on the surface of the cover glass 18 is photoexcited by the light emitted from the light source itself when the light source 16 is turned on. Alternatively, the photocatalyst layer 20 is photoexcited by sunlight during the day under the condition of being exposed to sunlight like a road lighting device. Upon photoexcitation, the surface of the photocatalyst layer 20 is made hydrophilic so that the contact angle with water is 10 ° or less, particularly about 0 °. Combustion products, such as carbon black and diesel particulates, are basically hydrophobic and therefore are unlikely to adhere to the surface of the superhydrophilized cover glass 18. Similarly, since the contact angle of inorganic substances such as mud and soil with water is 20 ° to 50 °, the surface of the cover glass 18 superhydrophilized so that the contact angle with water becomes about 0 °. It is hard to adhere to. Therefore, the surface of the cover glass 18 is kept clean for a long period of time, and the frequency of cleaning can be greatly reduced.

When the surface of the cover glass 18 is contaminated with contaminants, water is supplied to the surface of the cover glass 18 as needed, and the contaminants attached to the surface are easily washed away with water. The affinity of the superhydrophilized surface for water is greater than the affinity for hydrophobic substances such as combustion products. Therefore, if water is supplied to the surface of the cover glass 18, the hydrophobic substances such as combustion products will not be generated. It is released from the surface and easily rinsed with water. Cover glass 18
The cleaning is preferably performed by spraying water from a work vehicle running at low speed or high speed. In this way, traffic restrictions can be minimized. Alternatively, a sprinkler may be installed near the wall of the tunnel or the lighting device, and the cover glass 18 may be sprinkled with water as needed.

Example 1 Tetraethoxysilane Si was added to 86 parts by weight of an ethanol solvent.
6 parts by weight of (OC ₂ H ₅ ) ₄ (Wako Pure Chemical Industries), 6 parts by weight of pure water, and 2 parts by weight of 36% hydrochloric acid as a hydrolysis inhibitor of tetraethoxysilane were added and mixed to prepare a silica coating solution. Since the solution generated heat by mixing, the mixed solution was left to cool for about 1 hour. This solution was applied to the surface of a 10 cm square soda lime glass plate by the flow coating method,
Dried at a temperature of ° C. With drying, tetraethoxysilane was hydrolyzed to silanol Si (OH) _{4 first} , and then a thin film of amorphous silica was formed on the surface of the glass plate by dehydration condensation polymerization of silanol.

Next, tetraethoxy titanium Ti (OC ₂ H ₅ )
₄ (Merck) 0.1 part by weight of 36% hydrochloric acid as a hydrolysis inhibitor was added to a mixture of 1 part by weight of ethanol and 9 parts by weight of ethanol to prepare a titania coating solution, and this solution was dried on the surface of the glass plate. It was applied by a flow coating method in air. The coating amount was 45 μg / cm ² in terms of titania. Since the rate of hydrolysis of tetraethoxytitanium was extremely fast, part of the tetraethoxytitanium was hydrolyzed at the coating stage, and titanium hydroxide Ti (OH) ₄ began to form.

Next, the glass plate is heated to about 150 minutes for 1 to 10 minutes.
By maintaining the temperature at ℃, the hydrolysis of tetraethoxytitanium was completed, and the produced titanium hydroxide was subjected to dehydration polycondensation to produce amorphous titania. Thus, a glass plate in which amorphous titania was coated on amorphous silica was obtained. The glass plate was fired at a temperature of 500 ° C. to convert amorphous titania to anatase titania.

After leaving this sample in the dark for several days, 20 W
Black light blue (BLB) fluorescent light (Sankyo Electric, FL2
OBLB) was applied to the surface of the sample at an ultraviolet intensity of 0.5 mW / cm ² (ultraviolet intensity of energy higher than the band gap energy of anatase titania) for about 1 hour to obtain a # 1 sample. For comparison, a glass plate not coated with titania was prepared and used as a # 2 sample.

The contact angle between the # 1 sample and the # 2 sample with water was measured by a contact angle measuring instrument (Kyowa Interface Science Co., Ltd., Model CA-X150). The detection limit on the low angle side of this contact angle measuring instrument was 1 °. The contact angle was measured 30 seconds after a water droplet was dropped from the microsyringe on the sample surface. The reading of the measuring instrument with respect to water on the surface of the # 1 sample was 0 °, indicating superhydrophilicity. On the other hand, the contact angle of the # 2 sample with water was 30 to 40 °.

Oleic acid was applied to the surface of the glass plate, and the glass plate was immersed in water filled in a water tank while keeping the glass plate surface in a horizontal position. It was released from the surface of the board and surfaced.

Example 2 An amorphous titania was formed on the surface of a glass plate by applying a titanium chelate-containing liquid to the surface of a 10 cm square soda lime glass plate and subjecting the titanium chelate to hydrolysis and dehydration polycondensation. This glass plate was fired at a temperature of 500 ° C. to form a surface layer made of anatase type titania crystal. The film thickness of the surface layer was 7 nm. The surface of the obtained sample was irradiated with ultraviolet light for about 1 hour at an illuminance of 0.5 mW / cm ² using a BLB fluorescent lamp. The contact angle of the surface of the sample with water was measured with a contact angle measuring device (ERMA, model GI-1000, low angle side detection limit 3 °), and the contact angle reading was less than 3 °.

Example 3 In this example, a 10 cm square aluminum substrate was used as a base material. In order to smooth the surface of the substrate, it was previously coated with a silicone layer. For this reason, liquid A (silica sol) and liquid B (trimethoxymethylsilane) of the Japanese synthetic rubber coating composition "GLASCA" are mixed so that the weight ratio of liquid A and liquid B is 3: 1. This mixed solution was applied to an aluminum substrate and cured at a temperature of 150 ° C. to obtain a plurality of aluminum substrates (# 1 sample) coated with a base coat of silicone having a thickness of 3 μm.

The # 1 sample was then coated with the titania-containing paint. More specifically, anatase-type titania sol (NISSAN CHEMICAL, TA-15) is mixed with the above-mentioned "grasca" solution A (silica sol), diluted with ethanol, and then the above-mentioned "grasca" solution B is added to the titania-containing paint. A composition for use was prepared. The composition of this coating composition was 39 parts by weight of silica, 97 parts by weight of trimethoxymethylsilane, and 8 parts of titania.
It was 7 parts by weight. This coating composition was applied to the surface of a # 1 sample and cured at a temperature of 150 ° C. to form a top coat in which anatase-type titania particles were dispersed in a silicone coating, to obtain a # 2 sample.

Next, using a BLB fluorescent lamp for the # 2 sample, 0.5
Ultraviolet rays were irradiated for 5 days at an illuminance of mW / cm ² to obtain a # 3 sample. The contact angle of the surface of this sample with water is measured by a contact angle measuring device (ER
The contact angle reading was less than 3 ° when measured by MA). The contact angle of the # 2 sample before ultraviolet irradiation was measured and was found to be 70 °. When the contact angle of the # 1 sample was measured, it was 90 °. Further, the # 1 sample was irradiated with ultraviolet rays for 5 days under the same conditions as the # 2 sample, and the contact angle was measured. As a result, the contact angle was 85 °.

From this, it is understood that the silicone coating film is highly hydrophilized when the photocatalyst is contained in the silicone and the photocatalyst is photoexcited. It is considered that the organic group bonded to the silicon atom of the silicone molecule is substituted with the hydroxyl group by the photocatalytic action, and the hydrophilic silicone derivative is formed on the surface.

[0031]

According to the method of the present invention, the frequency of cleaning the cover glass of the tunnel / road lighting device can be greatly reduced, and the maintenance of the tunnel / road lighting device can be minimized. . Further, since the tunnel / road lighting device can be cleaned only by injecting water from the working vehicle that is running, traffic regulation can be minimized.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a lighting device to which the method of the present invention is applied.

[Explanation of symbols]

 10: Lighting device for tunnel 18: Cover glass 20: Photocatalyst containing layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Makoto Senkuni, 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture Totoki Equipment Co., Ltd. (72) Atsushi Kitamura Nakajima, Kokurakita-ku, Kitakyushu, Fukuoka 2-1, 1-1 Totoki Equipment Co., Ltd.

Claims (5)

[Claims] 1. A surface of a cover glass of a tunnel or road lighting device is covered with a transparent layer containing a semiconductor photocatalyst, and the photocatalyst is photoexcited to make the surface of the layer hydrophilic, and water is supplied to the surface of the layer. A method for cleaning a cover glass of a tunnel or road lighting device, which comprises washing away contaminants adhering to the surface of the layer. 2. The cleaning method according to claim 1, wherein the photocatalyst is optically excited by light emitted from the lighting device itself. 3. The cleaning method according to claim 1, wherein the water is supplied by spraying water on a cover glass. 4. The cleaning method according to claim 3, wherein the water is injected from a working vehicle. 5. The surface of a cover glass of a tunnel or road lighting device is coated with a transparent layer containing a semiconductor photocatalyst, and the photocatalyst is photoexcited to hydrophilize the surface of the layer, whereby hydrophobic contaminants are eliminated. A method for antifouling a cover glass of a tunnel or road lighting device, which comprises preventing adhesion to a surface.