Photocatalyst material, polyfunctional material using the same and its production

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a photocatalyst material used for a malodor decomposition apparatus, a water purification system in a circulating water channel, and a multifunctional material using the photocatalyst material, and a method for producing the same.

【0002】

[Conventional technology]

The photocatalytic material conventionally used for purifying water is usually plate-shaped or spherical. When the irradiation direction of the light source is fixed in a certain direction, the plate-shaped one is preferably spherical in order to enlarge the contact surface as the base material because the reaction with toxic gas and organic substances is limited to one side of the base material. ..

【0003】

A spherical base material is disclosed in Japanese Patent Application Laid-Open No. 7-24451. A photocatalytic material is attached to the surface of a stone or glass ball as a base material, and this is spread in a water tank to purify water in the water tank. , I try to sterilize.

【0004】

[Problems to be Solved by the Invention]

However, when a material that does not transmit ultraviolet rays such as stone is used as the base material, a portion that is not irradiated with light is generated, and the purification and bactericidal action by the photocatalyst is not exhibited in this portion.

【0005】

Even in the case of a light-transmitting base material such as glass, if the film thickness of the photocatalyst is increased, the ultraviolet transmittance becomes extremely small (close to 0), and the part other than the part that directly receives light is purified by the photocatalyst material. , The bactericidal action is not exhibited.

【0006】

[Means for solving problems]

In order to solve the above problems, the photocatalyst material according to the present invention is a photocatalyst material in which a photocatalyst film is formed on a base material, and the ultraviolet transmittance of the photocatalyst material as a whole is 0.1% or more, preferably 1 to 50. %. Here, the ultraviolet transmittance of the photocatalyst material means the ratio (I / I0) of the amount of light (I) transmitted through the base material and the photocatalyst film to the amount of incident light (I0).

【0007】

The base material preferably has a spherical shape, is made of glass or the like, and has an ultraviolet transmittance of 50% or more, and the photocatalyst film is, for example, TiO.₂Or TiO₂It is composed of a layer of a metal salt and a layer of a metal salt, and the ultraviolet transmittance thereof is preferably 3% or more, preferably 3% or more and 70% or less. In addition to the above, materials such as resins and ceramics that can transmit ultraviolet rays can be used as the base material, and TiSrO, which has high activity, can be used as the photocatalyst material.₃ , SnO₂, ZnO, WO₃ Etc. can be used.

【0008】

The reason why the ultraviolet transmittance of the base material is set to 50% or more is that if it is less than this, the amount of ultraviolet rays after the base material is transmitted becomes small, and the purification and bactericidal action of the photocatalyst cannot be sufficiently exerted. Was set to 3% or more because the amount of ultraviolet rays absorbed by the photocatalyst film becomes large below this, and the amount of ultraviolet rays after transmission is not sufficient to activate the photocatalyst. In addition, the larger the ultraviolet transmittance, the better, but if the thickness of the photocatalyst film is 0.1 μm or less, film formation becomes difficult and there is a problem in activity, so the thickness of the photocatalyst film should be 0.1 μm or more. Since the ultraviolet transmittance is 70% when the thickness is 0.1 μm, the ultraviolet transmittance is preferably 70% or less.

【0009】

Further, in the multifunctional material according to the present invention, the above photocatalytic material is directly held on the surface of a substrate such as tile, enamel or earthenware, or is held via a binder layer such as a glaze layer or a printing layer. By holding the photocatalytic material on the surface of the substrate in this way, hemispherical irregularities are formed on the surface of the tile or the like, and the substrate itself can have a photocatalytic function.

【0010】

Further, in the method for producing a photocatalyst material according to the present invention, a substrate having a predetermined ultraviolet transmittance, that is, an ultraviolet transmittance of 0.1% or more when the photocatalyst material is used, and a photocatalyst dispersion are agitated, and the surface of the substrate is stirred. After forming a photocatalyst film on the surface, it was fired at 300 ° C or higher and 900 ° C or lower.

【0011】

In addition, when dipping the base material in a liquid sol in which photocatalytic fine particles are dispersed or spray coating, the mixing ratio of the added sol to the base material is in the range of 1.0 / 100 to 3.6 / 100, and the uniformity of the film. It is preferable from the viewpoint of strength. Further, the uniformity and strength of the film can be improved by heating the base material to 80 to 110 ° C in advance.

【0012】

In order to increase the activity of the spherical photocatalyst obtained as described above, it is also possible to coat with a metal such as Ag, Cu, Pt. In this case, the following method is used. That is, after immersing the photocatalyst material in the metal salt aqueous solution, the photocatalyst surface is coated with metal by irradiation with an ultraviolet lamp and photoreduction plating. At this time, the excess metal salt remaining on the surface is washed. Cleaning methods include long-term immersion in water and cleaning with a dilute acid solution. By cleaning the excess metal salt, it is possible to prevent the elution of metal ions that adversely affect the ecosystem, and to maintain the antibacterial, filth decomposition, and algae-proofing effects of the metal and photocatalyst for a long period of time. Can be done.

【0013】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to Examples 1 to 6. (Example 1) Decomposition of ammonia is shown as an example of the effects of the substrate, photocatalyst film, and translucency on the activity of the spherical photocatalyst material. In the examples, evaluation samples of the photocatalytic material were prepared by changing the TiO2 coating amount on various spherical substrates shown in (Table 1) below.

【0014】

[table 1]

<img file="JPH09248468A_D0001.tif" />【0015】

Figure 1 shows the deodorant function evaluation device (NH)₃Block block diagram of gas decomposition rate measuring device), Fig. 2 is TiO₂The figure showing the ammonia gas decomposition rate (%) with respect to the film thickness (μm), Fig. 3 shows the ultraviolet transmittance and NH of the photocatalyst material in which a photocatalyst film is formed on the base material.₃The graph showing the relationship with the gas decomposition rate, and (Table 2) show the ultraviolet transmittance and gas decomposition rate of each evaluation sample.

【0016】

[Table 2]

<img file="JPH09248468A_D0002.tif" />【0017】

The deodorant function evaluation device 10 includes a suction pump 11 that sucks air, activated carbon 12 that purifies the sucked air, and NH.₃Gas source 13, reaction vessel 15 containing evaluation sample 14, NH₃Cocks 16a and 16b that control the gas flow, gas sensor 17 that detects when the gas concentration is saturated, NH₃It is equipped with a gas detector tube 18 for detecting the gas concentration and a light source (BLB lamp) 19 for irradiating the evaluation sample 14.

【0018】

From Fig. 2, when a ceramic ball with almost 0 ultraviolet transmittance is used as the base material, the ammonia gas decomposition rate increases slightly with the increase in film thickness, and the increase reaches a plateau (saturation) at 2 μm or more. On the other hand, when translucent glass beads and resins are used, the ammonia gas decomposition rate has a maximum value when the ultraviolet transmittance of the base material is between 0.2 and 1.2 μm. It can be seen that up to a film thickness of 2 μm, the saturation value observed when ceramics are used as the base material is exceeded.

【0019】

Further, in order to improve the gas decomposition rate from FIG. 3 and (Table 2), it is necessary that the ultraviolet transmittance of the entire photocatalyst material having the photocatalyst film formed on the substrate is at least 0.1% or more, which is 1%. It can be said that 50% or more is preferable. From the same viewpoint, the ultraviolet transmittance of the photocatalyst film is preferably 3% or more and 70% or less.

【0020】

Here, an evaluation method using the deodorant function evaluation device will be described. Fill the reaction vessel (internal volume: 460 ml) 15 with 100 g of beads (evaluation sample 14), open the cock 16a, and allow ammonia gas (20 to 30 ppm) to flow. At this time, the cock 16b is open in the exhaust direction. After sufficient circulation of ammonia gas and confirmation by the gas sensor 17 that the gas concentration has reached saturation, the cock 16b is closed and the flow of ammonia gas is used as a circulatory system. The gas concentration at this time is examined by the detector tube 18, and the initial value C0 is obtained. Irradiate the beads (evaluation sample 14) with BLB light from the light source (BLB lamp) 19. After 1 hour, the gas concentration C in the reaction vessel 15 is examined by the detector tube 18. Obtain the decomposition rate from the value detected by. (Decomposition rate = C / C0) [0021] [0021]

(Example 2) Regarding the influence of the translucency of the base material on the activity of the spherical photocatalyst material, the case of water treatment in a circulating water tank is shown. FIG. 4 is an explanatory diagram of the circulating water tank. The circulating water tank 20 includes a water tank (internal volume 60 liters, circulating water volume 40 liters) 21, a pump 22 for circulating water W, a flow path 23, and beads (spherical photocatalyst material). It has 24 and circulates as shown by the arrow.

【0022】

TiO on a spherical substrate with various translucency₂(See Table 3) was coated, and in order to investigate the photocatalytic activity of each photocatalyst, a spherical photocatalyst material 24 was installed in the circulating water tank 20, and the COD value, the number of Escherichia coli, and the amount of algae generated were periodically examined. TiO₂-When using a Cu-based photocatalyst, the concentration of Cu ions was also examined.

【0023】

[Table 3]

<img file="JPH09248468A_D0003.tif" />【0024】

As a manufacturing method of each catalyst material, 7.5% of TiO per 100 g of the base material₂1.2 g of sol was applied, kneaded, and then calcined at 800 ° C. Membrane TiO₂-When using Cu, use 3% Cu (CH) for the photocatalyst prepared in the same way.₃COO₎₂Was immersed in and irradiated with a BLB lamp for 5 minutes. After that, it was immersed in a 1% HCl solution for 10 to 30 seconds to wash the excess metal. The results regarding the water quality, the number of E. coli, and the amount of algae generated for each substrate are shown in (Table 4) below.

【0025】

[Table 4]

<img file="JPH09248468A_D0004.tif" />【0026】

From Table 4, it can be seen from the comparison of No. 1 and No. 3 that the translucency of the base material affects the photocatalytic effect (water quality, number of E. coli, amount of algae generated). Further, in the water tank of the system (No. 2) coated with Cu, the amount of Cu elution after 180 days of circulation was substantially unchanged from that at the start of circulation. Therefore, TiO₂-The reduction of water pollution rate, reduction of E. coli, and anti-algae effect seen in Cu-based water tanks are not just for elution of Cu ions, but for Cu and TiO adsorbed by photoreduction.₂It can be seen that the photocatalytic effect of is stable and maintained for a long period of time.

【0027】

(Example 3) About the influence of the translucency of the base material and the translucency of the photocatalyst film on the activity of the spherical catalyst AgNO₃The case of using (silver nitrate) coloration will be described. Translucency of substrate, TiO₂Photocatalytic beads were prepared by changing the translucency of the membrane. The types of base materials are shown in (Table 5) below.

【0028】

[Table 5]

<img file="JPH09248468A_D0005.tif" />【0029】

Here, the method for measuring the spherical photocatalytic material by silver nitrate coloring is to fill a 50 ml beaker with a 50 g sample and add AgNO.₃Add 1% solution of the above, soak the sample (glass beads), and then irradiate the BLB lamp. At this time, the sample should not be agitated.

【0030】

The color values before and after Ag coloration are measured (at this time, in the color value measurement, the sample is agitated each time the measurement is performed to reduce the variation in data). The color value is calculated, and this value is taken as the silver nitrate color value (ΔE). The silver nitrate coloration values (ΔE) of Samples 1 to 4 measured by the above method are shown in (Table 6) below.

【0031】

[Table 6]

<img file="JPH09248468A_D0006.tif" />【0032】

From (Table 6), the magnitude of the silver nitrate color value (ΔE) is the base material TiO.₂It can be seen that it reflects the translucency of.

【0033】

(Example 4) TiO which is a photocatalyst₂TiO on film strength₂The effect of the mixing ratio of the sol and the base material is shown below. First, for 100 g of glass beads with a particle size of 1 mm, TiO₂Only 0.45g, 0.6g, 0.9g, 1.2g, 1.5g, 1.8g, 3.6g and 12g of sol were mixed (however, TiO).₂Since the film thickness is constant, TiO₂The concentration of the sol was changed) (see Table 7). Then, after stirring and drying, firing was performed at 800 ° C. for 40 minutes. The strength of the film of each bead was evaluated by the following method using a stirrer in water.

【0034】

[Table 7]

<img file="JPH09248468A_D0007.tif" />【0035】

The method for evaluating the film strength will be described. Take 5 g of fired photocatalytic glass beads into a beaker containing 50 ml of water. Add a magnetic stirrer and stir for 90 seconds. Replace the water and stir for 60 seconds. Collect the water used in and measure the turbidity with a turbidity meter. When the turbidity value is 0 to 9, it is evaluated as , when it is 10 to 15, it is evaluated as Δ, and when it is 16 or more, it is evaluated as ×, and the strength of the film is judged from the turbidity of water.

【0036】

From (Table 7), in the production of spherical photocatalyst, TiO₂The mixing ratio of the sol and the base material is TiO with respect to the base material beads (100).₂It can be seen that high strength is obtained when the mixing ratio of the sol is (1.0 / 100) to (3.6 / 100).

【0037】

However, for the base beads (100), TiO₂TiO formed with a large mixing ratio of sol (3.6 / 100 or more) or a small mixing ratio (less than 1.2 / 100)₂Since the film becomes uneven and an extremely thick portion is generated, the strength of the film decreases.

【0038】

(Example 5) In producing photocatalytic glass, TiO₂The effect of heating the substrate to be coated on the film strength is shown below. First, glass beads having a particle size of 0.5 mm were prepared and heated at 20, 80, 110 and 140 ° C, respectively. After that, TiO so that the film thickness of one bead is 0.4 μm with respect to the amount of the base material.₂Was coated, stirred and dried, and then calcined at 800 ° C. for 40 minutes. The results of examining the film strength of the fired photocatalytic glass beads by the same method as in Example 4 are shown in (Table 8) below.

【0039】

[Table 8]

<img file="JPH09248468A_D0008.tif" />【0040】

From (Table 8), it can be seen that the film strength was improved by heating the substrate. It is considered that this is because the film was made uniform by heating the base material. However, there is an appropriate temperature range for the heating temperature. That is, if the heating temperature of the film is too high, the film dries quickly, the thickness becomes non-uniform, and the strength decreases. The temperature range is considered to be 80 to 110 ° C from Table 8. From this result, it was found that heating the base material is effective for improving the film strength.

【0041】

(Example 6) As shown in FIG. 5, a ceramic tile 30 is used as a substrate, and SiO is used on the surface thereof.₂-Al₂O₃-Na / KO₂A binder layer 31 made of frit adjusted to a softening temperature of 480 ° C was formed, and a photocatalyst material 32 having a photocatalyst film 32b formed on the surface of the translucent base material 32a was placed on the binder layer 31. Bake at 700 ° C. The photocatalyst material 32 may be placed directly on the surface of the tile base and then fired at 700 ° C. Not limited to the ceramic tile base material, it is also possible to use a material having a fire resistance higher than the melting temperature of the photocatalyst material such as metal as the substrate, and heat and melt a part of the photocatalyst material to hold it on the surface of the substrate. Further, in Example 6, the substrate is made of ceramic tile, but the present invention is not limited to this, and a substrate of metal, resin, or the like may be used and held by an adhesive or the like.

【0042】

In this way, by using tiles whose substrate surface is coated with a photocatalyst for walls and ceilings, in addition to antibacterial properties, the hemispherical surface exerts a unique design, and the indoor illuminance with tiles is increased. It can be used as a multifunctional material that can be enhanced.

【0043】

[Effect of the invention]

As described above, according to the photocatalyst material according to the present invention, it is possible to obtain a spherical photocatalyst material in which the photocatalyst is uniformly and firmly coated. Further, the light irradiated to the spherical photocatalyst material passes through the medium in an amount sufficient to cause the photocatalyst laminated on the back surface or under the photocatalyst to act on the light source. Therefore, the photocatalyst on the back surface or the lower layer of the photocatalyst body acts effectively, and the function as a photocatalyst is improved.

【0044】

Further, according to the method for producing a photocatalyst material according to the present invention, a uniform and high-strength photocatalyst film can be fused to the surface of a base material. At the same time, it is possible to prevent the elution of metal ions that adversely affect the ecosystem, and it is possible to stably maintain the antibacterial, filth decomposition, and algae-proofing effects of the metal and photocatalyst for a long period of time.

【0045】

Further, according to the multifunctional material using the photocatalyst material according to the present invention, hemispherical irregularities are formed on the surface of the tile or the like by using the tile or the like holding the photocatalyst material on the substrate surface for the wall or ceiling. In addition to exhibiting a unique design, it is possible to increase the illuminance indoors with tiles and the like.

[Simple explanation of drawings]

[Figure 1]

Deodorant function evaluation device (NH₃Block block diagram of gas decomposition rate measuring device) [Figure 2]

TiO₂The figure which showed the ammonia gas decomposition rate (%) with respect to the film thickness (μm) [Fig. 3]

Graph showing the relationship between the ultraviolet transmittance of the photocatalyst material and the gas decomposition rate [Fig. 4]

Explanatory drawing of the circulating water tank [Fig. 5]

Enlarged sectional view of a multifunctional material using a photocatalytic material [Explanation of symbols]

10 ... Deodorant function evaluation device, 11 ... Suction pump, 12 ... Activated carbon, 13 ... NH3 source, 14 ... Evaluation sample, 15 ... Reaction vessel, 16a, 16b ... Cock , 17 ... gas sensor, 18 ... gas detector tube, 19 ... light source, 20 ... circulating water tank, 21 ... water tank, 22 ... pump, 23 ... flow path, 24 .. Beads (spherical photocatalyst material), 30 ... tile as substrate, 31 ... binder layer, 32 ... photocatalyst material, 32a ... translucent substrate, 32b ... photocatalyst film.