JP3643290B2 - Sound insulation wall - Google Patents

Description

【００３９】
この表から分かるように、チタニア含有シリコーン塗膜の表面は光励起により高度に親水化された。また、放電処理によりチタニア含有シリコーン塗膜の耐摩耗性を向上させることができる。＃１３を３週間暗所に放置したが、表面の水との接触角は４゜に止まった。
【００４０】
【発明の効果】
本発明によれば、遮音壁の表面は汚れにくく、しかも降雨の都度雨水の作用によりセルフクリーニングされるので、特に清掃をしなくても遮音壁は充分清浄に維持される。従って、道路や鉄道の景観が良好に維持され、快適な環境が実現される。特に、従来放置されていた遮音壁の外側面は効果的にセルフクリーニングされる。遮音壁の一部又は全部に透明パネルが使用してある場合には、透明パネルの透光性が維持されるので、日照権問題を回避することができる。超親水化された表面の汚れは水で容易に洗い流されるので、遮音壁の内側面などを洗浄したい場合には、水を供給するだけで必要に応じ極めて簡単に洗浄することができる。走行中の作業車から水を噴射することにより洗浄する場合には、交通規制を廃止し又は最小限にすることができ、作業の安全を確保することができる。
【図面の簡単な説明】
【図１】本発明の遮音壁の斜視図である。
【図２】図１に示した遮音壁の一部の拡大断面図である。
【図３】光触媒含有シリコーン層の表面のラマン分光スペクトルを示す。
【符号の説明】
１０： 遮音壁 １６： 遮音壁の構成パネル １８： 光触媒含有層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sound insulation wall of a road or a railway, and more particularly, a sound insulation having antifouling property and self-cleaning property. On the wall Related.
[0002]
[Prior art]
Sound insulation walls are used to prevent noise on roads and railways. In the early days, the installation of sound insulation walls was limited to the vicinity of schools and hospitals, but today they tend to be installed in residential and commercial areas. For the sound insulation wall, a metal panel having a glass wool sound absorbing material sandwiched between an aluminum plate or a steel plate, or a precast concrete panel is used. In addition, on elevated roads in urban areas, transparent panels made of plastic or glass such as polycarbonate are also used to guarantee the right of sunshine for residents along the line and solve the problem of sunshine. Transparent panels also have the advantage of improving the landscape of roads and railways and are particularly suitable for areas with good views.
[0003]
[Problems to be solved by the invention]
The sound insulation walls of roads are contaminated by soot in the exhaust gas, tire dust, and dust that soars from the road surface and ground. In particular, the dirt on the sound insulation wall is conspicuous on the inner surface. The sound insulation wall of the railway is also polluted by the falling dust. If the sound insulation wall is dark and dirty, it gives an unpleasant impression and damages the road and railway landscape. In the case of a transparent panel, the translucency is reduced due to dirt, so that the guarantee of the right of sunshine is insufficient. Therefore, it is desirable to clean the sound insulation wall as necessary.
[0004]
Conventionally, the inner surface of the sound insulation wall is cleaned by brush cleaning. This requires greater or lesser traffic restrictions (lane restrictions, etc.), which hinders smooth road traffic and is dangerous. Moreover, since the cleaning of the sound insulation wall involves work at a high place, it is expensive and dangerous. There is currently no countermeasure for dirt on the outer surface of the sound insulation wall. In the case of transparent panels, the advantages are diminished, so countermeasures are desired from the viewpoint of landscape issues and the right to sunshine.
[0005]
An object of the present invention is to provide a sound insulation wall that is not easily contaminated and is self-cleaning (self-cleaning).
[0006]
[Means for Solving the Problems]
The inventor has discovered that photoexcitation of a semiconductor photocatalyst results in a highly hydrophilic surface of the photocatalyst. The present invention is based on such discovery. According to the present invention, the surface of the sound insulation wall is coated with a layer containing a semiconductor photocatalyst. The sound insulation wall is irradiated with the sun during the day, and the photocatalyst of the surface photocatalyst containing layer is photoexcited by sunlight. With photoexcitation, the surface of the photocatalyst-containing layer is highly hydrophilized so that the contact angle with water is 10 ° or less, more specifically 5 ° or less, and particularly about 0 °. Once highly hydrophilized, the surface hydrophilicity persists even at night. In a region where light such as road illumination is irradiated with sufficient illuminance, the photocatalyst is photoexcited even at night.
[0007]
Hydrophobic substances such as smoke in exhaust gas, tire wear powder, and urban dust are difficult to adhere to the highly hydrophilic surface. In addition, the superhydrophilic surface adsorbs moisture in the atmosphere, so it is difficult to be electrostatically charged. Therefore, it is difficult to adsorb floating dust electrostatically.
[0008]
In addition, sound insulation walls are sometimes exposed to rainfall. Since the affinity of the superhydrophilic surface for water is greater than the affinity for hydrophobic substances such as combustion products and tire wear powder, dirt attached to the surface of the sound insulation wall is affected by rainwater in areas that have been subjected to rain. Easily released from the surface and washed away by rainwater. Thus, the surface of the sound insulation wall is self-cleaned (self-cleaned) every time it rains.
[0009]
The sound insulation wall may be actively cleaned by supplying water to the surface of the sound insulation wall. Water can be supplied by a sprinkler installed on the sound insulation wall. Alternatively, water may be jetted from a work vehicle traveling on a roadside belt or the like. In this case, traffic regulation is not required or can be minimized. By spraying water, contaminants adhering to the surface of the sound insulation wall are washed away with water, and the surface is cleaned. The above features and advantages of the present invention, as well as other features and advantages, will be apparent from the description of the following examples.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, the sound insulation wall 10 includes, for example, a vertical wall 12 and a curved wall 14 that is curved upward on the road. It can be constructed of a metal panel having a glass wool sound absorbing material sandwiched between steel plates, a precast concrete panel, a transparent panel such as glass or polycarbonate, or a combination thereof.
[0011]
As shown in FIG. 2, the surface of the sound insulation wall component panel 16 is covered with a transparent layer 18 containing a semiconductor photocatalyst. The photocatalyst containing layer 18 is provided on at least the inner surface (surface facing the road), preferably both the front and back surfaces of the sound insulation wall. Of course, it may be provided only in a heavily contaminated area. The film thickness of the photocatalyst containing layer 18 is preferably 0.2 μm or less. In this way, sufficient transparency can be ensured and color development due to light interference can be prevented. Furthermore, the thinner the film thickness, the better the abrasion resistance (peeling resistance) of the photocatalyst containing layer 18.
[0012]
As a semiconductor photocatalyst, titania (TiO ₂ ) Is most preferred. Titania is harmless, chemically stable, and available at low cost. Either anatase-type titania or rutile-type titania can be used. When photocatalytic titania is photoexcited by ultraviolet light, water is converted to hydroxyl (OH) by photocatalysis. ^- ) In the form of), and as a result, the surface is considered to be superhydrophilic. Other photocatalysts that can be used include ZnO and SnO ₂ , SrTiO _Three , WO _Three , Bi ₂ O _Three , Fe ₂ O _Three There are metal oxides such as Since these metal oxides, like titania, contain metal elements and oxygen on the surface, it is considered that they adsorb surface hydroxyl groups (OH-).
[0013]
It is preferable to add a platinum group metal such as Pt, Pd, Rh, Ru, Os, and Ir to the photocatalyst containing layer 18. When a platinum group metal is added, the photooxidation activity of the photocatalyst can be enhanced, and the decomposition of air pollutants such as NOx, SOx, and CO in the exhaust gas can be promoted.
[0014]
When the sound insulation wall constituting panel 16 is made of glass, the photocatalyst-containing layer 18 is applied to the panel 16 with a sol containing particles of photocatalyst (for example, anatase titania), and the temperature is equal to or lower than the softening point of the glass. It can be formed by sintering. In this case, in order to prevent alkali network modification ions such as sodium in the glass from diffusing from the glass layer into the photocatalytic layer 18, the surface of the panel 16 is previously coated with an intermediate layer 20 such as silica. Is preferred. When the photocatalyst is titania, the photocatalyst containing layer 18 is preferably blended with about 10 to 50% by weight of silica or tin oxide. In this way, the surface of the photocatalyst layer 18 can be made superhydrophilic to such an extent that the contact angle with water becomes 0 ° during photoexcitation. In particular, when the photocatalyst layer 18 is formed of a material having a high refractive index such as titania, it is preferable to mix silica with titania. If it does so, the refractive index of the photocatalyst layer 18 can be suppressed and reflection of light can be prevented.
[0015]
Alternatively, the photocatalyst-containing layer 18 may be formed by forming a thin film of an amorphous photocatalyst precursor on the surface of the panel 16 and heating the amorphous thin film to crystallize it to convert it into a photoactive photocatalyst. Good. For example, when the photocatalyst is titania, an amorphous titania thin film is formed on the surface of the panel 16 and then fired at a temperature not lower than 400 ° C. and not higher than the softening point of the glass, thereby converting the amorphous titania into crystalline titania (anatase). Or rutile). The photocatalyst layer 18 thus formed is superhydrophilic to such an extent that the contact angle with water becomes 0 ° during photoexcitation.
[0016]
Amorphous titania is obtained by adding a hydrolysis inhibitor such as hydrochloric acid or ethylamine to titanium alkoxide (for example, tetraethoxy titanium, tetraisopropoxy titanium, tetra n-propoxy titanium, tetrabutoxy titanium, tetramethoxy titanium), and ethanol. After dilution with alcohol such as propanol or propanol, with partial or full hydrolysis, the mixture is spray coated, flow coated, spin coated, dip coated, roll coated and other coatings It can be formed by applying to the surface of the panel 16 by the method and drying at a temperature from room temperature to 200 ° C. By drying, the hydrolysis of titanium alkoxide is completed to produce titanium hydroxide, and an amorphous titania layer is formed on the surface of the substrate by dehydration condensation polymerization of titanium hydroxide. Instead of the titanium alkoxide, other organic titanium compounds such as titanium chelate or titanium acetate may be used.
[0017]
Alternatively, amorphous titania is an inorganic titanium compound, such as TiCl. _Four Or Ti (SO _Four ) ₂ Is applied to the surface of the panel 16 by spray coating, flow coating, spin coating, dip coating or roll coating, and then the inorganic titanium compound is dried at a temperature of about 100 to 200 ° C. for hydrolysis and dehydration condensation polymerization. It can form by attaching | subjecting.
[0018]
When the sound insulation wall component panel 16 is formed of plastic such as polycarbonate, precast concrete, or aluminum, the panel 16 cannot be heated at a high temperature. Therefore, in this case, a preferable method for forming the photocatalyst-containing layer 18 exhibiting superhydrophilicity such that the contact angle with water is 0 ° is an uncured or partially cured silicone (organopolysiloxane) or It is to use a coating composition in which photocatalyst particles are dispersed in a coating film forming element made of a silicone precursor. After this coating composition is applied to the surface of the panel 16 and the coating film forming element is cured, when the photocatalyst is photoexcited, the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by the photocatalytic action of the photocatalyst. The surface of the photocatalyst layer 18 is superhydrophilic.
[0019]
The coating film forming element of this coating composition includes methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltri-t-butoxysilane; ethyltrichlorosilane, ethyltrichlorosilane. Bromosilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltri-t-butoxysilane; n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxy Silane, n-propyltriisopropoxysilane, n-propyltri-t-butoxysilane; n-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyl Riethoxysilane, n-hexyltriisopropoxysilane, n-hexyltri-t-butoxysilane; n-decyltrichlorosilane, n-decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyl Triisopropoxysilane, n-decyltri-t-butoxysilane; n-octadecyltrichlorosilane, n-octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n- Octadecyltri-t-butoxysilane; phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltri-t-butoxy Silane: Tetrachlorosilane, Tetrabromosilane, Tetramethoxysilane, Tetraethoxysilane, Tetrabutoxysilane, Dimethoxydiethoxysilane; Dimethyldichlorosilane, Dimethyldibromosilane, Dimethyldimethoxysilane, Dimethyldiethoxysilane; Diphenyldichlorosilane , Diphenyldibromosilane, diphenyldimethoxysilane, diphenyldiethoxysilane; phenylmethyldichlorosilane, phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane; trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, trimethyl Ethoxyhydrosilane, triisopropoxyhydrosilane, tri-t-butoxyhydrosilane; vinyltrichlorosilane, vinyl Tribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane; trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysilane, trifluoropropyltri Ethoxysilane, trifluoropropyltriisopropoxysilane, trifluoropropyltri-t-butoxysilane; γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane , Γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri-t-butoxysilane; Liloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ -Methacryloxypropyltri-t-butoxysilane; gamma-aminopropylmethyldimethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltriisosilane Propoxysilane, 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 partial hydrolysates thereof; and mixtures thereof.
[0020]
When the sound insulation wall component panel 16 is made of plastic, an intermediate layer 20 is disposed between the panel 16 and the photocatalyst layer 18 in order to prevent the plastic from being deteriorated by the photooxidation action of the photocatalyst. Is preferred. This intermediate layer can be formed of silicone, fluororesin, or silica. In the case where the component panel 16 is made of precast concrete or metal, it is preferable to coat silicone or the like in advance in order to smooth the surface of the substrate.
[0021]
Thus, the photocatalyst containing layer 18 formed on the surface of the sound insulating wall 10 is exposed to the sun during the day, and the photocatalyst is photoexcited by sunlight (including not only direct sunlight but also scattered light). When the sound insulation wall constituting panel 16 is formed of a transparent panel, light passes through the panel, so that the photocatalyst layers on both the front and back surfaces are excited. In addition, when road lighting is installed, the photocatalyst is photoexcited at night.
[0022]
Along with photoexcitation, the surface of the photocatalyst-containing layer 18 is hydrophilized so that the contact angle with water is 10 ° or less, particularly about 0 °. Since combustion products such as carbon black and diesel particulates are basically hydrophobic, they are difficult to adhere to the surface of the sound insulation wall that has been made superhydrophilic. In addition, the superhydrophilic surface adsorbs moisture in the atmosphere, so it is difficult to be electrostatically charged. Therefore, it is difficult to adsorb floating dust electrostatically. Furthermore, since the contact angle of inorganic substances such as mud and soil with water is 20 ° to 50 °, it adheres to the surface of the sound insulation wall that has been made superhydrophilic so that the contact angle with water becomes about 0 °. Hard to do.
[0023]
The sound insulation wall 10 is occasionally exposed to rain. Since the affinity of the ultra-hydrophilic sound insulation wall surface for water is greater than the affinity for hydrophobic substances such as combustion products, hydrophobic substances such as combustion products are easily released from the sound insulation wall surface and washed away by rainwater. It is. In this way, the sound insulation wall is self-cleaned each time the superhydrophilic surface receives rainfall. In particular, since rain is often applied to the outer surface of the curved portion 14 of the sound insulation wall, this portion is susceptible to self-cleaning.
[0024]
Rain is accompanied by dust that floats in the atmosphere, but the surface of the sound insulation wall is highly hydrophilic, so when rain flows down the surface of the sound insulation wall, the dust that accompanies the rain adheres to the surface of the sound insulation wall. There is nothing to do.
[0025]
An area of the sound insulation wall that is not self-cleaned due to rain (for example, the inner surface of the curved wall 14) can be positively cleaned by supplying water with a sprinkler (not shown) or the like installed at an appropriate location of the sound insulation wall. it can. Alternatively, as shown in FIG. 1, the dirt can be easily removed simply by injecting water from the work vehicle 22 running on the roadside belt or the like.
[0026]
【Example】
Example 1
A 10 cm square soda lime glass plate was used as a substrate, and this glass plate was coated with an amorphous silica layer in advance. For this reason, tetraethoxysilane Si (OC ₂ H _Five ) _Four (Wako Pure Chemical Industries) 6 parts by weight, 6 parts by weight of pure water and 2 parts by weight of 36% hydrochloric acid as a hydrolysis inhibitor for tetraethoxysilane were added and mixed to prepare a silica coating solution. Since the solution generated heat by mixing, the mixture was allowed to cool for about 1 hour. This solution was applied to the surface of a soda lime glass plate by a flow coating method and dried at a temperature of 80 ° C. As it dries, tetraethoxysilane undergoes hydrolysis, first silanol Si (OH) _Four Subsequently, an amorphous silica thin film was formed on the surface of the glass plate by dehydration condensation polymerization of silanol.
[0027]
Next, tetraethoxy titanium Ti (OC ₂ H _Five ) _Four (Merck) A titania coating solution was prepared by adding 0.1 part by weight of 36% hydrochloric acid as a hydrolysis inhibitor to a mixture of 1 part by weight of ethanol and 9 parts by weight of ethanol, and this solution was added to the surface of the glass plate with dry air. It was applied by the flow coating method. The coating amount is 45μg / cm in terms of titania ² It was. Since the hydrolysis rate of tetraethoxytitanium is extremely fast, a part of tetraethoxytitanium is hydrolyzed at the application stage, and titanium hydroxide Ti (OH) _Four Began to generate.
[0028]
Next, the glass plate is kept at a temperature of about 150 ° C. for 1 to 10 minutes to complete the hydrolysis of tetraethoxytitanium, and the produced titanium hydroxide is subjected to dehydration condensation polymerization to form amorphous titania. Generated. Thus, a glass plate in which amorphous titania was coated on the amorphous silica layer was obtained. This glass plate was baked at a temperature of 500 ° C. to convert amorphous titania into anatase titania.
[0029]
After leaving this sample in the dark for several days, a 20 W black light blue (BLB) fluorescent lamp (Sankyo Electric, FL20BLB) was used to apply 0.5 mW / cm on the surface of the sample. ² No. 1 sample was obtained by irradiating ultraviolet rays for about 1 hour at an ultraviolet illuminance of 1 (UV illuminance with energy higher than the band gap energy of anatase titania). For comparison, a glass plate without a titania coating was prepared and used as a sample # 2.
[0030]
The contact angle between the # 1 sample and the water of the # 2 sample was measured with a contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., model CA-X150). The detection limit of the low angle side of this contact angle measuring device was 1 °. The contact angle was measured 30 seconds after a water droplet was dropped from the microsyringe onto the sample surface. The reading of the measuring instrument with respect to water on the surface of # 1 sample was 0 °, indicating super hydrophilicity. In contrast, the contact angle of the # 2 sample with water was 30 to 40 °.
[0031]
Example 2
An amorphous titania was formed on the surface of the 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 condensation polymerization. This glass plate was baked at a temperature of 500 ° C. to form a surface layer made of anatase-type titania crystals. The film thickness of the surface layer was 7 nm. The surface of the obtained sample is 0.5 mW / cm using a BLB fluorescent lamp. ² Was irradiated with ultraviolet rays for about 1 hour. When the contact angle between the surface of the sample and water was measured with a contact angle measuring device (ERMA, model GI-1000, low angle detection limit 3 °), the contact angle reading was less than 3 °.
[0032]
Example 3
In this example, a 10 cm square aluminum substrate was used as the base material. In order to smooth the surface of the substrate, it was previously coated with a silicone layer. For this purpose, the liquid A (silica sol) and the liquid B (trimethoxymethylsilane) of the composition composition “Glaska” for Japanese synthetic rubber were mixed at a weight ratio of 3: 1, and this mixed liquid was mixed with an aluminum substrate. And cured at a temperature of 150 ° C. to obtain a plurality of aluminum substrates (# 1 sample) coated with a 3 μm-thick silicone base coat. Next, anatase-type titania sol (Nissan Chemical, TA-15, average crystallite size 12 nm) and the above-mentioned “Glaska” solution A were mixed, diluted with ethanol, and further added with “Glaska” solution B above. A containing coating composition was prepared. The composition of the coating composition was 33 parts by weight of silica sol, 11 parts by weight of trimethoxymethylsilane, and 56 parts by weight of titania sol. This coating composition was applied to the surface of sample # 1 and cured at a temperature of 150 ° C. to form a topcoat in which anatase-type titania particles were dispersed in a silicone coating film, thereby obtaining sample # 2. Next, using a 20W BLB fluorescent lamp for sample # 2, 0.5mW / cm ² The sample was irradiated with ultraviolet rays at an illuminance of 5 days for # 3 sample. When the contact angle between the surface of this sample and water was measured with a contact angle measuring device (manufactured by ERMA, model GI-1000), the contact angle reading was less than 3 °. The contact angle of sample # 2 before UV irradiation was measured and found to be 70 °. The contact angle of # 1 sample was measured and found to be 90 °. Furthermore, 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. The contact angle was 85 °. From the above, it has been found that silicone is highly hydrophilic when it contains a photocatalyst and is excited by ultraviolet irradiation even though it is inherently hydrophobic.
[0033]
# 2 Using a mercury lamp on the sample, 22.8 mW / cm ² The sample was irradiated with ultraviolet rays at an ultraviolet illuminance of 2 hours to obtain a # 4 sample. Raman spectroscopic analysis of the # 2 sample before irradiation and the # 4 sample after irradiation was performed. For comparison, the sample # 1 was also irradiated with ultraviolet light under the same conditions, and the Raman spectroscopic analysis of the sample before and after irradiation was performed. The Raman spectrum is shown in the graph of FIG. Since the Raman spectra before and after the irradiation of the sample # 1 were the same, the graph of FIG. Referring to the graph of FIG. 3, in the Raman spectrum of sample # 2, the wave number is 2910 cm. ^-1 A large peak of C-H bond symmetry expansion and contraction of sp3 hybrid orbital is observed at the position of 2970 cm. ^-1 A large peak of C—H bond antisymmetric stretching of the sp3 hybrid orbital is observed at the position of. Therefore, the C—H bond is present in the # 2 sample. In the spectrum of # 4 sample, wave number 2910cm ^-1 Position and 2970cm ^-1 There is no peak at any of the positions. Instead, wave number 3200cm ^-1 A wide-width OH bond symmetrical stretch with a peak at the position is recognized. Thus, the # 4 sample does not have C—H bonds, but instead has O—H bonds. On the other hand, in the Raman spectrum of sample # 1, the wave number is 2910 cm before and after irradiation. ^-1 A large peak of C-H bond symmetry stretching of sp3 hybrid orbital is observed at ^-1 A large peak of C—H bond antisymmetric stretching of the sp3 hybrid orbital is observed at the position of. Therefore, it is confirmed that C—H bond exists in the # 1 sample. From the above, it is considered that when a silicone containing a photocatalyst is irradiated with ultraviolet rays, a silicone derivative in which the organic group bonded to the silicon atom of the silicone molecule is replaced with a hydroxyl group by photocatalysis is formed on the surface. .
[0034]
Example 4
A 10 cm square polycarbonate plate (# 1 sample) was used as the substrate. In order to improve the bondability of the silicone hard coat, first, a primer primer for silicone (made by Shin-Etsu Silicone, PC-7A) is applied to the polycarbonate plate by spray coating, and then dried at 120 ° C for 20 minutes to primer the polycarbonate plate. Covered with a resin layer to obtain a # 2 sample. Next, a silicone-based hard coating agent (manufactured by Shin-Etsu Silicone, KP-85) was applied to the # 2 sample by a spray coating method and then dried at 120 ° C. for 60 minutes to obtain a # 3 sample. In addition, a primer coating (made by Toshiba Silicone Co., Ltd., PH-91) is applied to the same polycarbonate plate by a spray coating method and dried at 120 ° C for 20 minutes. A coating agent (manufactured by Toshiba Silicone, “Tosgard”) was applied by spray coating and dried at 120 ° C. for 60 minutes to obtain a # 4 sample.
[0035]
Next, in order to improve the bondability of the titania-containing silicone topcoat, using a corona surface treatment device (manufactured by Kasuga Denki), using a wire electrode, the gap between the electrode tip and the sample surface 2 mm, voltage 26 kV, frequency 39 kHz, By subjecting the surfaces of # 1 to # 4 samples to hydrophilization by performing high frequency corona discharge treatment at a sample feed rate of 4.2 m / min, # 5 to # 8 samples were obtained.
[0036]
Next, the same titania-containing coating composition as used in Example 3 was applied to samples # 1, # 5 to # 8 by the flow coating method, and then cured by heat treatment at 120 ° C. for 30 minutes. As a result, samples # 9 to # 13 coated with a titania-containing silicone topcoat were obtained.
[0037]
For the # 9 to # 13 samples, the abrasion resistance (peeling resistance) of the titania-containing silicone topcoat and the degree of hydrophilization by titania photoexcitation were measured. Abrasion resistance was evaluated by whether or not the top coat peeled off at the same time when the cellophane tape was applied from one end to the other end of each sample surface and then peeled off quickly. The degree of hydrophilization is 0.6 mW / cm using a BLB fluorescent lamp on the surface of each sample. ² The change in the contact angle with water before and after being irradiated with ultraviolet rays at an illuminance of about 48 hours was measured by measuring with a contact angle measuring device (model CA-X150, manufactured by Kyowa Interface Science). The results obtained are shown in the following table.
[0038]
[Table 1]

[0039]
As can be seen from this table, the surface of the titania-containing silicone coating film was highly hydrophilized by photoexcitation. Moreover, the abrasion resistance of the titania-containing silicone coating film can be improved by the discharge treatment. # 13 was left in the dark for 3 weeks, but the contact angle with water on the surface remained at 4 °.
[0040]
【The invention's effect】
According to the present invention, since the surface of the sound insulation wall is not easily soiled and is self-cleaned by the action of rain water every time it rains, the sound insulation wall can be maintained sufficiently clean even without any particular cleaning. Therefore, the landscape of roads and railways is well maintained and a comfortable environment is realized. In particular, the outer surface of the sound insulation wall that has been left alone is effectively self-cleaned. When a transparent panel is used for part or all of the sound insulation wall, the translucency of the transparent panel is maintained, so that the right to sunshine can be avoided. Since the dirt on the superhydrophilic surface is easily washed away with water, if it is desired to wash the inner surface of the sound insulation wall, etc., it can be washed very simply as needed by simply supplying water. When washing is performed by jetting water from a traveling work vehicle, traffic regulations can be abolished or minimized, and work safety can be ensured.
[Brief description of the drawings]
FIG. 1 is a perspective view of a sound insulation wall of the present invention.
FIG. 2 is an enlarged cross-sectional view of a part of the sound insulation wall shown in FIG.
FIG. 3 shows a Raman spectrum of the surface of the photocatalyst-containing silicone layer.
[Explanation of symbols]
10: Sound insulation wall 16: Sound insulation wall component panel 18: Photocatalyst containing layer

Claims (4)

A sound insulation wall of a road or a railway, wherein at least a part of the sound insulation wall is made of a transparent material, the surface of the sound insulation wall is covered with a transparent semiconductor photocatalyst containing layer, and the sound insulation wall is made of plastic, the sound insulation wall and the photocatalyst An intermediate layer for preventing the plastic from being deteriorated by the photooxidation action of the photocatalyst is disposed between the photocatalyst and the surface of the semiconductor photocatalyst containing layer is water as the photocatalyst is photoexcited by sunlight. Converted to a contact angle of 10 degrees or less, so that hydrophobic contaminants are prevented from adhering to the surface of the sound insulation wall, or are attached to the surface of the sound insulation wall when the sound insulation wall is exposed to rain. A sound insulation wall characterized in that it is used in sunlight, where the soil is washed away by rainwater. 2. The sound insulating wall according to claim 1, wherein the photocatalyst-containing layer includes one photocatalyst selected from the group consisting of TiO ₂ , ZnO, SnO ₂ , SrTiO ₃ , WO ₃ , Bi ₂ O ₃ , and Fe ₂ O ₃ . The sound insulation wall according to claim 1 , wherein the photocatalyst is anatase type titania. The sound insulation wall according to claim 1 , wherein the intermediate layer is one selected from the group consisting of silicone, fluororesin, and silica.

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