JP3334767B2 - Building materials with moisture absorption and release functions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a building material having a moisture absorbing / releasing function suitable for maintaining an atmosphere at a comfortable humidity.

[0002]

2. Description of the Related Art An environment where a person feels comfortable is at a temperature of 20 to 2 degrees.
It is an atmosphere at 6 ° C. and a relative humidity of 50 to 70%. In order to obtain a comfortable temperature, various heaters, coolers, cooling / heating devices and the like are used. Comfortable humidity is obtained with air conditioners such as dehumidifiers and humidifiers. All devices consume a large amount of energy represented by electricity and fossil fuels. Recently, building structures aiming at energy saving have been adopted. For example, there is a structure in which openings such as windows and doorways are reduced to enhance the heat insulation of a building. In addition, sunlight may be directly or indirectly taken in to heat or cool the room. With respect to temperature regulation, these methods can achieve comfortable environmental conditions. However, for the humidity control, laying a hygroscopic agent, a hygroscopic sheet, etc. under the floor or the ceiling is adopted, but no effective means has been put into practical use in place of the energy consuming device.

[0003]

By simply arranging a hygroscopic agent such as silica gel, when the amount of adsorbed water reaches a saturated amount, no hygroscopic property is exhibited. Therefore, in a rainy season or the like in which a high humidity atmosphere continues for a long time, the moisture absorbing function cannot be maintained. Further, in an environment where moisture is constantly high, such as a bathroom or a kitchen, the properties of the moisture absorbent are lost in a short period of time. As a result, such an environment is an environment where mold generation is severe, despite being a living space that is strongly required to be kept clean. Further, in industrialized houses such as a two-by-fore construction method and a prefabricated house, the opening areas of windows, doorways, etc. are designed to be small in order to improve heat insulation, sound insulation, airtightness and the like. For this reason, industrialized houses have poor ventilation compared to ordinary houses, and dew condensation easily occurs on floors, walls, ceilings, and the like. Condensation water remains in the form of patterns on the surface of building materials and significantly deteriorates the impression of the living environment. The present invention has been devised in order to solve such a problem, and provides a building material capable of maintaining an optimum humidity condition for a long period of time by providing a function of repeatedly increasing a moisture absorbing ability. Aim.

[0004]

According to the construction material of the present invention, in order to achieve the object, a film in which a moisture absorbent and a photocatalyst are blended is formed on the surface of the base material, and the moisture absorbent is activated by the photocatalyst. . As the hygroscopic agent, γ-Al ₂ O ₃ , zeolite, silica gel, water-absorbing polymer and the like are used. Examples of the water-absorbing polymer include starch, acrylate kraft polymer, and cross-linked carboxymethyl cellulose. As the photocatalyst, TiO ₂ , WO ₃ , ZnO, SrTiO ₃ ,
BaTi ₄ O ₉ , RbPb ₂ Nb ₃ O ₁₀ , ZrO ₂ , metal sulfide and the like are used. From the viewpoint of effectively adsorbing moisture, the hygroscopic agent is preferably as large as the specific surface area. Specifically, if the specific surface area is 10 m ² / g or more, it is used as the moisture absorbent of the present invention. The photocatalyst also preferably has a specific surface area of 10 m ² / g or more in consideration of the activating action on the moisture absorbent. Alternatively, a photocatalyst having a small diameter can be used, and the photocatalyst can be attached to the surface of the moisture absorbent.

[0005] A blend of a moisture absorbent and a photocatalyst is applied to the surface of a substrate in an appropriate form such as spraying, painting, and electrodeposition.
It becomes a film with a moisture release function. As the base material, a metal plate, paper, a synthetic resin plate, a particle board, a gypsum plate, a woven fabric, a nonwoven fabric, a concrete plate, or the like, which is conventionally known as a building material, is used. Depending on the type of moisture absorbent and photocatalyst,
Usually, 0.3 to 3 parts by weight of a photocatalyst is blended with 1 part by weight of a moisture absorbent and applied to the surface of a substrate. When the mixing ratio of the photocatalyst is less than 0.3 parts by weight, the effect of activating the hygroscopic agent is reduced. On the other hand, when the compounding ratio of the photocatalyst exceeds 3 parts by weight, the activation effect is large, but the ratio of the hygroscopic agent is relatively small, and the required hygroscopic property cannot be obtained. The coating may further comprise a conventional coating former.

[0006]

When the TiO ₂ powder is irradiated with light having a wavelength of about 400 nm or less, electrons and holes are generated in the TiO ₂ powder. The electrons are consumed in the reduction reaction of atmospheric oxygen. The holes have the function of decomposing water on the surface into oxygen and hydrogen. Such an effect can be similarly obtained in a photocatalyst other than the TiO ₂ powder. The present invention uses the action exhibited by the photocatalyst to activate the moisture absorbent. That is, the moisture adhering to the moisture absorbent mixed with the photocatalyst is
It undergoes a photocatalytic decomposition reaction and is released from the moisture absorbent.
The decomposition reaction by the photocatalyst is started by irradiating light having a wavelength corresponding to the photocatalyst, that is, light having a wavelength corresponding to energy equal to or larger than the band gap of the photocatalyst which is a semiconductor. Therefore, when a certain amount of water is adsorbed, the adsorbed water is released by irradiating the surface of the building material with light emitted from, for example, a high-pressure mercury lamp. As a result, the water content of the hygroscopic agent is reduced, and the hygroscopic ability is restored. As a result, the desired properties of the hygroscopic agent are maintained for a long period of time, and the building material has good hygroscopicity. The light used for moisture release is
For example, when the photocatalyst is TiO ₂ , the wavelength is shorter than 413 nm, and in WO ₃ , the wavelength is shorter than 459 nm. As such a light source, a high-pressure mercury lamp, a xenon lamp, a halogen lamp, or the like is used.

[0007]

【Example】

Example 1: γ-Al ₂ O ₃ powder having an average particle size of 0.02 μm and a specific surface area of 86.4 m ² / g as a hygroscopic agent, and an average particle size of 0.04 μm and a specific surface area of 44.2 m ² as a photocatalyst
/ G TiO ₂ powder was used. A γ-Al ₂ O ₃ powder and a TiO ₂ powder were mixed at a weight ratio of 1: 1, glass frit and water glass were added as binders, and water was added to prepare a slurry. The slurry is applied to the surface of a steel sheet having a thickness of 0.5 mm so that the dry film thickness becomes 0.7 mm, and
It was baked by heating to 50 ° C. for 10 minutes. A test piece of 10 cm × 10 cm was cut out from the steel sheet on which the film was formed. After heating and drying the test piece at 150 ° C., it was kept in a dry atmosphere at a temperature of 20 ° C. and a relative humidity of 30% for 2 hours. Assuming that the test piece after the holding was in a stable and dry state, the film weight was measured to be 3.2 g. A test piece subjected to moisture adsorption and drying treatment is subjected to a temperature of 30 ° C. and a relative humidity of 80%.
And the weight of the test piece was measured periodically. As a result, as the standing time elapses, the weight of the test piece increased as shown in Table 1. This weight increase is due to the fact that the moisture in the humid atmosphere was adsorbed on the surface film of the test piece.

[0008]

[Table 1]

The test piece on which the released moisture was adsorbed was taken out of the thermo-hygrostat into the atmosphere at a temperature of 20 ° C. A 400 KW high-pressure mercury lamp was installed at a position 1 m away from the surface of the test piece. Light having a wavelength of 400 nm was emitted from a high-pressure mercury lamp to irradiate the surface of the test piece.
When the weight of the test piece after irradiation was measured, the weight was reduced as shown in Table 2. Considering that the amount of heat given to the test piece from the high-pressure mercury lamp is small, it is assumed that most of the weight loss is caused by the oxidation reaction of the adsorbed moisture promoted by the photocatalyst.

[0010]

[Table 2]

As is clear from Table 2, it can be seen that, depending on the amount of water adsorbed, most of the adsorbed water is released by irradiation for 30 minutes or more. After the release of water, the film of the test piece had a weight of 3.2 g, which was substantially the same as the initial weight, and the adsorption ability was recovered. Therefore, the same characteristics were exhibited even when the water adsorption and the release of the adsorbed water were repeatedly performed. From the above, γ-Al ₂ O ₃ and Ti
It was confirmed that the steel sheet on which the O ₂ film was formed can be used as a building material having a function of absorbing and releasing moisture.

Therefore, a cubic building having an inner space of 5 m × 5 m × 5 m was constructed from the steel sheet on which the film was formed, and a light source for emitting light having a wavelength of 400 nm was arranged inside the building. In addition, 1m ×
A 1 m open / close window was provided. The window was opened for 10 minutes every 3 hours to replace the air, and the light source was turned on for only 20 minutes every 8 hours. Under these conditions, the relative humidity in the building was measured continuously for 10 days. The weather condition during the measurement was cloudy with a relative humidity of 80% or more for the first three days from the start of the measurement.
The fourth day was sunny with a relative humidity of 60% or less, the fifth day was sometimes cloudy with a relative humidity of 70% or more, and the sixth to the end of the measurement was continuous rain. In particular, on the 7th and 8th days from the start of the measurement, the atmosphere was extremely humid with heavy rainfall and a relative humidity of 95% or more in most cases. Even under such adverse conditions, the relative humidity in the building was maintained at an average of 60%, and was only 65-70% at the highest time.

Example 2 A compound for electrodeposition coating was prepared by changing the combination of a moisture absorbent and a photocatalyst as shown in Table 3. The compound was applied to a stainless steel plate having a thickness of 0.5 mm and dried at 150 ° C. to form a film having a dry film thickness of 200 μm. A test piece of 10 cm × 10 cm was cut out from this stainless steel plate, and after drying, the film weight W ₀ was measured. The wet process for 8 hours under the same conditions as in Example 1 subjected to the test piece was determined a coating weight W ₁ after wet treatment. Further, the test piece subjected to the wet treatment was irradiated with light for 10 minutes under the same conditions as in Example 1 to release water, and then the film weight W ₂ was obtained. Table 3 also shows the change in weight due to moisture adsorption and moisture release.

[0014]

[Table 3]

In the above example, a moisture absorbing / releasing film was formed on a metal plate such as a steel plate or a stainless steel plate.
However, the present invention is not limited to this,
Even when a film was formed on another substrate such as a synthetic resin plate, a particle board, a gypsum plate, a woven fabric, a nonwoven fabric, and a concrete plate, a film whose moisture absorption ability was similarly recovered by light irradiation was formed. Further, the film composed of the moisture absorbent and the photocatalyst is effective not only for absorbing and releasing moisture, but also for adsorbing offensive odor components in the atmosphere. In particular, when γ-Al ₂ O ₃ is used as a moisture absorbent component, organic substances causing a bad smell are also effectively adsorbed and removed. Organic substances adsorbed from the atmosphere are released by similar light irradiation, and the desired properties of the film are restored.

[0016]

As described above, in the present invention, a film containing a moisture absorbent and a photocatalyst is formed on the surface of a substrate. The photocatalyst activates a reaction for releasing adsorbed moisture from the desiccant at the time of light irradiation, and recovers the hygroscopic ability of the desiccant. Therefore, after the film is exposed to a humid atmosphere, the moisture is released by periodically irradiating light, and the moisture absorbing ability of the film is restored. Therefore, the building material of the present invention is useful as a building material that maintains a favorable living environment for a long period of time by repeating light irradiation.

 ──────────────────────────────────────────────────続 き Continuing on the front page Judge Hiroshi Kihara Judge Makoto Nakata Judge Judge Yuki Yamaguchi (56) References JP-A-3-81150 (JP, A) JP-A-3-73304 (JP, A) Kaikai 61-146345 (JP, A)

Claims (4)

(57) [Claims] 1. A photocatalyst of 0.3 to 1 part by weight of a hygroscopic agent.
A building material in which a film containing a moisture absorbent and a photocatalyst in a proportion of 3 parts by weight is formed on the surface of a substrate. 2. The building material according to claim 1, wherein the hygroscopic agent is one or more selected from γ-Al ₂ O ₃ , zeolite, silica gel, and a water-absorbing polymer. 3. A photocatalyst comprising TiO ₂ , WO ₃ , ZnO, Sr
_{TiO 3, BaTi 4 O 9,} RbPb 2 Nb 3 O 10, Zr
The building material according to claim 1, wherein the building material is at least one selected from O ₂ and metal sulfide. 4. The building material according to claim 1, wherein the base material is a metal plate, paper, synthetic resin plate, particle board, gypsum plate, woven fabric, non-woven fabric or concrete plate.