JPH09224490A - Vinyl house ceiling and dew condensation prevention method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vinyl house provided with a ceiling whose inner surface is covered with a transparent layer containing a semiconductor photocatalyst, for which hydrophilicity is imparted to a surface by optical excitation to form a uniform water film even when dew condensation occurs, preventing it from dropping from the regular parts of the ceiling and preventing root rot. SOLUTION: This vinyl house is provided with the ceiling whose inner surface is covered with the transparent layer formed by binding the particles of the semiconductor photocatalyst such as anatase-type titania or the like by amorphous silica and the hydrophilicity is imparted to the surface of the transparent layer accompanying the optical excitation of the photocatalyst. Also, it is preferable to install the vinyl house outdoor, expose it to the irradiation or the sun, impart the hydrophilicity to the surface of the transparent layer and thus, spread condensed water to the uniform water film when the condensed water is condensed to dew on the inner surface of the ceiling and prevent the dew condensation of the vinyl house ceiling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condensation concentration preventing structure and method for a ceiling of a vinyl greenhouse.

[0002]

2. Description of the Related Art In the field of agriculture, a vinyl house formed of vinyl sheets is used as a simple greenhouse.

[0003]

When the inner surface of the vinyl house reaches a temperature below the dew point, moisture in the air inside the vinyl house is condensed, and dew condensation occurs on the inner surface of the vinyl house.
Condensed water that has condensed on the ceiling of the vinyl house is fused with each other to gradually grow into large water droplets, and when it becomes sufficiently large, it separates from the ceiling and falls by its own weight. The drop points of the condensed water droplets tend to be concentrated on a specific fixed part of the ceiling. Therefore, it has been pointed out that there is a problem that root crops occur in the agricultural products directly below the point of fall.

An object of the present invention is to provide a vinyl house ceiling structure in which the dropping points of condensed water droplets are not concentrated at a specific position on the ceiling. Another object of the present invention is to provide a method for preventing the falling points of condensed water drops from concentrating on a specific position on the ceiling.

[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, and according to the present invention, the inner surface of the ceiling of the vinyl house is coated with a transparent layer containing a semiconductor photocatalyst. When a vinyl house is installed in a field, the vinyl house is exposed to the sun during the day, and the sunlight penetrates the vinyl sheet to photoexcite the photocatalyst in the photocatalyst-containing layer on the inner surface of the ceiling. Upon photoexcitation, the surface of the photocatalyst-containing layer is made hydrophilic so that the contact angle with water is 10 ° or less, preferably 5 ° or less, and more preferably about 0 °. Once hydrophilized, the hydrophilicity of the surface of the photocatalyst-containing layer is maintained even at night. When a greenhouse is provided with an artificial light source such as a fluorescent lamp to illuminate crops at night, the photocatalyst is also photoexcited at night.

Since the surface of the photocatalyst-containing layer on the inner surface of the ceiling is highly hydrophilic as described above, when dew condensation occurs in cold weather or at night, the condensed water spreads evenly on the surface of the photocatalyst-containing layer. Such a water film is formed. When the thickness of the water film increases with the progress of dew condensation, the condensed water flows down along the side wall of the vinyl house with the water film formed, without forming water droplets hanging from the ceiling. Therefore, condensed water droplets do not drop from a specific position on the ceiling of the greenhouse.

The photocatalyst is most preferably anatase type titania (TiO ₂ ). Titania is harmless, chemically stable, and available at low cost. Rutile titania can also be used. When photocatalytic titania is photoexcited by ultraviolet light, it is believed that water is chemically adsorbed on the surface in the form of hydroxyl groups (OH ⁻ ) by photocatalysis, and as a result, the surface becomes superhydrophilic. Other photocatalysts which can be used include metal oxides such as _{ZnO, SnO 2, SrTiO 3,} WO 3, Bi 2 O 3, Fe 2 O 3. Similar to titania, these metal oxides have metal elements and oxygen on the surface,
Surface hydroxyl (OH ^-) is considered combed adsorb. The thickness of the photocatalyst containing layer is preferably 0.2 μm or less. By doing so, sufficient transparency can be secured.

The photocatalyst-containing layer can be formed by binding photocatalyst particles to a vinyl sheet with amorphous silica. Therefore, a precursor of crystalline titania sol and amorphous silica (for example, tetraalkoxysilane such as tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetramethoxysilane, etc .; their hydrolyzates; A silanol; or a polysiloxane having an average molecular weight of 3000 or less) is applied to the surface of the vinyl sheet and hydrolyzed as necessary to form silanol.
The photocatalyst-containing layer in which titania is bound with amorphous silica is formed by subjecting silanol to dehydration polycondensation by heating at a temperature of 0 ° C. or higher.

Another preferred method of forming a photocatalytic layer exhibiting superhydrophilicity such that the contact angle with water is 0 ° is uncured or partially cured silicone (silicon resin) or a precursor of silicone. A coating composition comprising photocatalyst particles dispersed in a coating film-forming element comprising This coating composition is applied to the surface of a vinyl sheet, after curing the coating film-forming element, 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 is made superhydrophilic.

There are several advantages to this approach. Since the silicone paint can be cured at room temperature or a relatively low temperature, it can be applied to a base material formed of a non-heat resistant material such as a vinyl sheet. This coating composition containing a photocatalyst can be applied by brush coating, spray coating, roll coating or the like. Since the silicone paint has a siloxane bond, it has sufficient resistance to the photooxidation action of the photocatalyst. Still another advantage of the photocatalytic coating composed of the photocatalyst-containing silicone paint is that once the surface is superhydrophilized, it maintains the superhydrophilic property for a long time even if it is kept in a dark place, and can be used as a fluorescent lamp. It is to restore the super hydrophilicity even with the light of the interior lighting.

The 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.

In order to prevent the vinyl sheet from being deteriorated by the photooxidation action of the photocatalyst, it is preferable to dispose a photooxidation-resistant intermediate layer between the vinyl sheet and the photocatalyst layer. This intermediate layer can be formed of silicone (silicon resin), fluororesin, or silica.

The superhydrophilization phenomenon by the photocatalyst can be realized by a photocatalytic action weaker than the photooxidation action by the photocatalyst. Therefore, another way to prevent the deterioration of the vinyl sheet is to suppress the photooxidation action of the photocatalyst. For this purpose, the thickness of the photocatalyst containing layer is set to 0.1.
μm or less, or one or two of alkali metal, alkaline earth metal, alumina, silica, zirconia, antimony oxide, amorphous titania, and hydrous titania in the photocatalyst containing layer.
More than one species can be added.

[0015]

Example 1 A 10 cm square vinyl sheet 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 "Glaska" are mixed so that the weight ratio of liquid A and liquid B is 3: 1. This mixed solution was applied to a vinyl sheet and cured at a temperature of 60 ° C. to obtain a sample coated with a silicone base coat having a film thickness of 3 μm. Next, anatase-type titania sol (Nissan Chemical Co., Ltd., TA-15) and the above-mentioned "grasca" solution A are mixed and diluted with ethanol, and then "grasca" solution B is added to obtain a titania-containing coating composition. It was adjusted. The composition of the coating composition was 3 parts by weight of silica, 1 part by weight of trimethoxymethylsilane, and 4 parts by weight of titania. Apply this coating composition to the surface of the sample and
To form a topcoat in which the anatase titania particles were dispersed in the silicone coating.

A 20 W black light blue fluorescent lamp (Sankyo Denki, FL20BLB) was used on the surface of this sample to give 0.5 mW / cm.
After irradiating ultraviolet rays for 1 week with ultraviolet illuminance of ² (ultraviolet illuminance of energy higher than the band gap energy of anatase-type titania), the contact angle with the water on the surface is measured by a contact angle measuring instrument (Kyowa Interface Science Co., Ltd. type 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 measuring instrument read 0 °, indicating superhydrophilicity. Next, both ends of this sample were fixed with tape in a closed container, a beaker containing hot water was placed below the sample, and the state of condensed water was observed. The condensed water became a uniform water film, and no growth of water drops was observed.

Example 2 A 10 cm square vinyl sheet was previously coated with an amorphous silica layer. Therefore, 86 parts by weight of ethanol solvent, 6 parts by weight of tetraethoxysilane Si (OC ₂ H ₅ ) ₄ (Wako Pure Chemical Industries, Ltd.), 6 parts by weight of pure water, and 36% hydrochloric acid as a hydrolysis inhibitor of tetraethoxysilane 2 A silica coating solution was prepared by adding and mixing parts by weight. Since the solution heats up when mixed,
The mixture was left to cool for about 1 hour. Apply this solution to the surface of vinyl sheet by flow coating method, and
Dried at a temperature of. As it was dried, tetraethoxysilane was first hydrolyzed to silanol Si (OH) ₄ ,
Subsequently, a thin film of amorphous silica was formed on the surface of the vinyl sheet by dehydration condensation polymerization of silanol. Next, tetraethoxysilane (Wako Pure Chemical Industries, Ltd.) 0.69 g and anatase type titania sol (Nissan Kagaku, TA-15, average particle size 0.01 μm) 1.07
g, 29.88 g of ethanol and 0.36 g of pure water were mixed to prepare a coating solution. This coating solution was applied to the surface of the vinyl sheet by the spray coating method. By holding this vinyl sheet at a temperature of about 150 ° C for about 20 minutes, tetraethoxysilane is hydrolyzed and dehydrated by polycondensation, and a coating of anatase-type titania particles bound with an amorphous silica binder is used. Formed on the surface of the sheet. The weight ratio of titania and silica was 1.

After irradiating this sample with ultraviolet rays under the same conditions as in Example 1, the contact angle with water on the surface was measured and the contact angle was 0 °. Furthermore, when the sample was placed above the beaker containing hot water as in Example 1, no growth of water droplets was observed.

Comparative Example For comparison, the same vinyl sheet used in Example was irradiated with ultraviolet rays under the same conditions as in Example 1, and then the contact angle with water on the surface was measured with a contact angle measuring instrument. However, the contact angle with water was 70 °. When the sample was placed above the beaker containing hot water, growth of water droplets was confirmed.

[0020]

As can be seen from the above test, according to the present invention, even if dew condensation occurs on the ceiling of the greenhouse, the condensed water spreads evenly on the surface of the photocatalyst layer to form a uniform water film. Therefore, condensed water drops will not fall from a fixed place on the ceiling. Therefore, root rot of the crop can be prevented. In addition, since root rot does not occur in the field immediately below the fixed part of the ceiling, it is possible to secure the planting area and improve the yield.

Front page continued (72) Inventor Atsushi Kitamura 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka Totoki Equipment Co., Ltd. (72) Inventor Makoto Senkoku 2-chome, Nakajima-Kogaku-ku, Kitakyushu, Fukuoka No. 1 Totoki Equipment Co., Ltd.

Claims (6)

[Claims] 1. A vinyl greenhouse, comprising a ceiling having an inner surface covered with a transparent layer containing a semiconductor photocatalyst, and the surface of the layer is hydrophilized by photoexcitation of the photocatalyst. 2. The greenhouse according to claim 1, wherein the layer comprises photocatalyst particles bound by amorphous silica. 3. The layer is formed of silicone in which photocatalyst particles are dispersed, and the surface of the layer has an organic group bonded to a silicon atom of a silicone molecule at least partially substituted with a hydroxyl group by the action of the photocatalyst. The greenhouse according to claim 1, wherein the greenhouse is made of a silicone derivative. 4. A photooxidation-resistant intermediate layer is arranged between the layer and the ceiling material in order to prevent the ceiling material from being deteriorated by the action of the photocatalyst. A vinyl house based on either of these. 5. A vinyl house having a ceiling inner surface coated with a transparent layer containing a semiconductor photocatalyst is placed outdoors and exposed to the sun, and the photocatalyst is photoexcited by sunlight to hydrophilize the surface of the layer. Therefore, when condensed water condenses on the inner surface of the ceiling, the condensed water is spread over a uniform water film, which is a method for preventing condensation of dew condensation on a vinyl house ceiling. 6. The layer is made of silicone having photocatalyst particles dispersed therein, and the organic group bonded to a silicon atom of a silicone molecule on the surface of the layer is at least partially a hydroxyl group as the photocatalyst is photoexcited by sunlight. The method according to claim 5, characterized in that