JPH09248468A - Photocatalyst material, polyfunctional material using the same and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photocatalyst material capable of efficiently developing purifying/sterilizing, action by a photocatalyst by specifying the ultraviolet transmisslvity of the photocatalyst material wherein a photocatalyst film is formed on a base material. SOLUTION: As a base material, a material such as glass having a spherical shape is used. A photocatalyst film is constituted of a TiO2 layer or a layer of TiO2 and a metal salt and the ultraviolet transmissivity thereof is set to 3% or more, pref., 3-70%. A photocatalyst is obtained by forming the photocatalyst film on the base material and the ultraviolet transmissivity of the photocatalyst material is set to 0.1% or more, pref., 1-50% as a whole. This photocatalyst material is produced by dipping the base material in a liquid sol having photocatalyst fine particles dispersed therein or applying the liquid sol to the base material by spray coating. By this method, the photocatalyst material capable of sufficiently developing purifying and sterilizing action is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst material used in a foul odor decomposition apparatus, a water purification system in a circulating water channel and the like, a multifunctional material using the photocatalyst material and a method for producing the same.

[0002]

2. Description of the Related Art Photocatalytic materials conventionally used for purifying water are usually plate-shaped or spherical. If the plate-shaped one is fixed in a fixed direction of the light source, the reaction with toxic gas or organic matter is limited to one side of the base material, so a spherical shape is preferable for increasing the contact surface as the base material. .

The spherical base material is disclosed in JP-A-7-24.
Japanese Patent Publication No. 451 discloses a photocatalyst material adhered to the surface of stone or glass beads as a base material, which is spread in a water tank to purify and sterilize water in the water tank.

[0004]

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

Further, even in the case of a transparent substrate such as glass, the ultraviolet transmittance becomes extremely small (close to 0) when the film thickness of the photocatalyst is increased, and the photocatalyst except for the portion directly receiving light. Purification and sterilization by the material is not exhibited.

[0006]

In order to solve the above problems, a photocatalyst material according to the present invention is a photocatalyst material in which a photocatalyst film is formed on a substrate, 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 substrate and the photocatalyst film to the amount of incident light (I0).

The substrate is preferably spherical and made of glass or the like and has a UV transmittance of 50% or more. The photocatalyst film is composed of, for example, TiO ₂ or a layer of TiO ₂ and a metal salt. The ultraviolet transmittance thereof is preferably 3% or more, more preferably 3% or more and 70% or less. In addition to the above, materials such as resins and ceramics capable of transmitting ultraviolet rays can be used as the base material, and as the photocatalytic material, highly active TiSrO ₃ , SnO ₂ , ZnO, WO _{3 can be used.}
Etc. can be used.

The ultraviolet transmittance of the base material is set to 50% or more because the amount of ultraviolet light after passing through the base material becomes small below this value.
This is because the photocatalyst cannot sufficiently exhibit the purifying and sterilizing effects. The reason why the ultraviolet ray transmittance of the photocatalyst is set to 3% or more is that below this, the ultraviolet absorption by the photocatalyst film becomes large, and the amount of ultraviolet rays after transmission becomes less than the photocatalyst. This is because it is not enough to activate. Further, the higher the ultraviolet transmittance, the better, but if the thickness of the photocatalyst film is 0.1 μm or less, the film formation becomes difficult and there is a problem in activity. Therefore, the thickness of the photocatalyst film is 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.

The multi-functional material according to the present invention is a tile,
The above-mentioned photocatalytic material was held directly on the surface of a substrate such as an enamel or ceramics, or it was held via a binder layer such as a glaze layer or a printing layer. Thus, by holding the photocatalytic material on the surface of the substrate, the tile or the like has hemispherical irregularities formed on the surface, and the substrate itself can have the photocatalytic function.

Further, in the method for producing a photocatalyst material according to the present invention, a substrate and a photocatalyst dispersion liquid having a predetermined ultraviolet transmittance, that is, an ultraviolet transmittance of 0.1% or more when the photocatalytic material is used, are stirred. Then, after forming the photocatalytic film on the surface of the substrate,
The firing was performed at 0 ° C or higher and 900 ° C or lower.

When the base material is dipped in a liquid sol in which photocatalyst fine particles are dispersed or spray coating is performed, the mixing ratio of the added sol to the base material is 1.0 / 10.
The range of 0 to 3.6 / 100 is preferable in terms of film uniformity and strength. Further, by heating the base material to 80 to 110 ° C. in advance, the uniformity and strength of the film are improved.

In order to enhance the activity of the spherical photocatalyst body obtained as described above, it is possible to coat it with a metal such as Ag, Cu or Pt. In this case, the following method is used. That is, after immersing the photocatalyst material in the metal salt aqueous solution, an ultraviolet lamp is irradiated to coat the metal on the photocatalyst surface by photoreduction plating. At this time, the excess metal salt remaining on the surface is washed. Examples of the cleaning method include immersion in water for a long time and cleaning with a dilute acid solution. By washing away excess metal salts, it is possible to prevent the elution of metal ions that adversely affect the ecosystem, and to sustain the antibacterial, dirt decomposition, and algae-proofing effects of the metal and photocatalyst for a long period of time. You can

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to Examples 1 to 6. (Example 1) The effects of the base material, the photocatalyst film, and the translucency on the activity of the spherical photocatalyst material will be described by taking the decomposition of ammonia as an example. In the examples, various spherical base materials shown in the following (Table 1) were used, and the coating amount of TiO2 was changed to prepare photocatalyst material evaluation samples.

[0014]

[Table 1]

FIG. 1 is a block diagram of the deodorizing function evaluation device (NH ₃ gas decomposition rate measuring device), and FIG. 2 is the TiO ₂ film thickness (μ
m) showing the ammonia gas decomposition rate (%),
FIG. 3 is a graph showing the relationship between the UV transmittance and the NH ₃ gas decomposition rate of the photocatalyst material having a photocatalyst film formed on the substrate, and (Table 2) shows the UV transmittance and gas decomposition rate of each evaluation sample. It is a thing.

[0016]

[Table 2]

The deodorizing function evaluation apparatus 10 comprises a suction pump 11 for sucking air, and an activated carbon 1 for cleaning the sucked air.
2, a NH ₃ gas source 13, a reaction container 15 containing the evaluation sample 14, and a cock 16 for controlling the flow of NH ₃ gas
a, 16b, a gas sensor 17 for detecting that the gas concentration is saturated, a gas detection pipe 18 for detecting the NH ₃ gas concentration,
Light source (BLB lamp) 19 for irradiating the evaluation sample 14
Is provided.

From FIG. 2, when a ceramic ball having an ultraviolet ray transmittance of almost 0 is used as a base material, the decomposition rate of ammonia gas slightly increases with an increase in the film thickness and becomes 2 μm.
When the glass beads and the resin having translucency are used, the ammonia gas decomposition rate is as follows.
It can be seen that the maximum value is reached in the range of 1.2 μm, and that the film thickness up to 2 μm exceeds the saturation value found when the ceramic is used as the base material.

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

Here, an evaluation method by the above deodorizing function evaluation device will be described. A reaction container (internal volume: 460 ml) 15 is filled with 100 g of beads (evaluation sample 14), the cock 16a is opened, and ammonia gas (20 to 30 ppm) is passed.
At this time, the cock 16b is open in the exhaust direction. After the gas sensor 17 confirms that the gas concentration has reached saturation by sufficiently circulating the ammonia gas, the cock 16b is closed and the flow of the ammonia gas is used as the circulation system. The gas concentration at this time is examined by the detector tube 18 to obtain an initial value C0. Light source (BLB lamp) for beads (evaluation sample 14)
BLB light is emitted from 19. After 1 hour, the gas concentration C in the reaction vessel 15 is detected by the detection tube 18
Investigate by Calculate the decomposition rate from the values detected at and. (Decomposition rate =
C / C0)

(Embodiment 2) Regarding the effect 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 view of the circulating water tank, and the circulating water tank 2
0 is a water tank (internal volume 60 liters, circulating water volume 40 liters) 21, pump 22 for circulating water W, flow path 2
3, beads (spherical photocatalyst material) 24 are provided and circulate as shown by an arrow.

TiO 2 on a spherical substrate having various translucency
₂ (see Table 3) was coated and a spherical photocatalyst material 24 was installed in the circulating water tank 20 in order to investigate the photocatalytic activity of each photocatalyst, and the COD value, the number of E. coli, and the amount of algae produced were periodically examined. When the TiO ₂ —Cu based photocatalyst was used, the Cu ion concentration was also examined.

[0023]

[Table 3]

As a method for producing each catalyst material, 1.2 g of 7.5% TiO ₂ sol was applied to 100 g of the base material, kneaded, and then baked at 800 ° C. When the film is made of TiO ₂ —Cu system, the photocatalyst prepared in the same manner is used as 3% Cu (C
Was irradiated with BLB lamp for 5 minutes and immersed in H _{3 COO) 2.} After this, the excess metal was washed by immersing it in a 1% HCl solution for 10 to 30 seconds. The results regarding the water quality, the number of E. coli, and the amount of algae produced for each substrate are shown in (Table 4) below.

[0025]

[Table 4]

From Table 4, a comparison between No1 and No3 shows 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 (No2) that is coated with Cu, the Cu elution amount after 180 days of circulation is substantially unchanged from that at the start of circulation. Therefore, the mitigation of the water pollution rate, the reduction of Escherichia coli, and the algae-preventing effect seen in the TiO ₂ —Cu system water tank are not merely due to elution of Cu ions, but the photocatalytic effect of Cu and TiO ₂ adsorbed by photoreduction is stabilized It can be seen that it will be maintained for a long time.

(Example 3) Effect of translucency of base material and translucency of photocatalyst film on activity of spherical catalyst AgNO
_An explanation will be given using the case of using ₃ (silver nitrate) coloring. Photocatalyst beads were prepared by changing the translucency of the substrate and the translucency of the TiO ₂ film. The types of substrates and the like are shown below (Table 5).

[0028]

[Table 5]

Here, the method for measuring the spherical photocatalytic material by silver nitrate coloration is as follows: A 50 ml beaker is filled with 50 g of a sample, a 1% solution of AgNO ₃ is put therein, and the sample (glass beads) is dipped, and then BLB is added. Illuminate the lamp. At this time, do not stir the sample.

The color value before and after the Ag coloration is measured (at this time,
In color value measurement, the sample is agitated after each measurement to reduce the dispersion of data). A color value is calculated, and this value is defined as a silver nitrate coloration 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]

From Table 6, it can be seen that the magnitude of the silver nitrate coloration value (ΔE) reflects the translucency of the substrate TiO ₂ .

Example 4 The influence of the mixing ratio of the TiO ₂ sol and the base material on the strength of the TiO ₂ film which is the photocatalyst is shown below. First, 100 g of glass beads with a particle size of 1 mm
In contrast, 0.45 g, 0.6 g, 0.9 of TiO ₂ sol
g, 1.2g, 1.5g, 1.8g, 3.6g, 12g
(However, the concentration of TiO ₂ sol was changed in order to keep the TiO ₂ film thickness constant) (see Table 7).
Then, after stirring and drying, baking was performed at 800 ° C. for 40 minutes. The film strength of each bead was evaluated by the following method using a stirrer in water.

[0034]

[Table 7]

A method for evaluating the film strength will be described. 5 g of the baked photocatalyst glass beads is placed in a beaker containing 50 ml of water. Insert a magnetic stirrer stirrer and stir for 90 seconds to wash. Replace water and stir for 60 seconds. Collect the water used in step 1 and measure the turbidity with a turbidimeter. When the turbidity value is 0-9, it is ○, when it is 10-15, it is △,
The strength of the film is judged from the degree of turbidity of water by setting 16 or more to x.

From Table 7, in the production of the spherical photocatalyst, the mixing ratio of the TiO ₂ sol and the base material was 10%.
0), the mixing ratio of TiO ₂ sol is (1.0 / 100)
It can be seen that a high strength can be obtained in the range of (3.6 / 100).

However, with respect to the base material beads (100), T
When the mixing ratio of iO ₂ sol is high (3.6 / 100 or more),
Alternatively, since the TiO ₂ film formed with a small amount of mixture (less than 1.2 / 100) has unevenness and an extremely thick portion is generated, the strength of the film decreases.

Example 5 In producing a photocatalytic glass, the effect of heating a substrate coated with TiO ₂ on the film strength is shown below. First, glass beads having a particle diameter of 0.5 mm are prepared, and the beads are 20, 80, 110 and 140, respectively.
Heated at ° C. After that, with respect to the amount of the base material, TiO ₂ is coated so that the thickness of one bead becomes 0.4 μm, and the mixture is stirred.
After drying, it was baked at 800 ° C. for 40 minutes. The results of examining the film strength of the calcined photocatalyst glass beads in the same manner as in Example 4 are shown in (Table 8) below.

[0039]

[Table 8]

By heating the substrate from (Table 8),
It can be seen that the film strength is improved. It is considered that this is because the film was made uniform by heating the base material. However, the heating temperature has an appropriate temperature range. That is,
If the heating temperature of the film is too high, the film will dry quickly and the thickness will become uneven, resulting in a decrease in strength. The temperature range is shown in Tables 8 to 8
It is considered to be 0 to 110 ° C. From these results, it was found that heating the base material is effective for improving the film strength.

(Embodiment 6) As shown in FIG. 5, a ceramic tile 30 was used as a substrate, and the surface thereof was SiO ₂ --Al ₂ O _3-.
A binder layer 31 made of frit having a softening temperature of Na / KO ₂ adjusted to 480 ° C. is formed, and a photocatalyst material 32 having a photocatalyst film 32b formed on the surface of a transparent substrate 32a is placed on the binder layer 31. After that, it is fired at 700 ° C. The photocatalyst material 32 may be directly placed on the surface of the tile base material and then baked at 700 ° C. Not limited to the ceramic tile base, it is also possible to use a substrate having a refractory degree higher than the solution temperature of the photocatalyst material, such as a metal, to heat and melt a part of the photocatalyst material and hold it on the substrate surface. Although the substrate is made of ceramic tile in the sixth embodiment, the present invention is not limited to this, and a substrate made of metal, resin or the like may be used and held by an adhesive or the like.

As described above, by using tiles whose surface is coated with a photocatalyst for walls and ceilings, in addition to antibacterial properties, the hemispherical surface exerts a peculiar design property, and indoors where tiles are provided. It can be used as a multifunctional material capable of increasing the illuminance.

[0043]

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

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 on the surface of the base material. At the same time, it is possible to prevent the elution of metal ions that have an adverse effect on the ecosystem, and it is possible to stably maintain the antibacterial, filth-decomposing, and algae-proofing effects of the metal and the photocatalyst over a long period of time.

Further, according to the multifunctional material using the photocatalyst material according to the present invention, by using a tile or the like having the photocatalyst material held on the substrate surface for a wall or a ceiling, hemispherical irregularities are formed on the surface of the tile or the like. While exhibiting the unique design formed,
It is possible to increase the indoor illuminance provided with tiles and the like.

[Brief description of drawings]

FIG. 1 Block diagram of deodorant function evaluation device (NH ₃ gas decomposition rate measurement device)

FIG. 2 is a diagram showing the ammonia gas decomposition rate (%) with respect to the TiO ₂ film thickness (μm).

FIG. 3 is a graph showing the relationship between the ultraviolet transmittance of the photocatalyst material and the gas decomposition rate.

[Fig. 4] Illustration of circulating water tank

FIG. 5 is an enlarged cross-sectional view of a multifunctional material using a photocatalytic material.

[Explanation of symbols]

10 ... Deodorizing function evaluation device, 11 ... Suction pump, 12 ... Activated carbon, 13 ... NH3 source, 14 ... Evaluation sample, 15 ... Reaction container, 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 base material, 32b
… Photocatalytic film.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C02F 1/32 C02F 1/32

Claims (14)

[Claims] 1. A photocatalyst material formed by forming a photocatalyst film on a substrate, wherein the photocatalyst material has an ultraviolet transmittance of 0.1% or more. 2. A photocatalyst material formed by forming a photocatalyst film on a substrate, wherein the photocatalyst material has an ultraviolet transmittance of 1% or more and 50% or less. 3. The photocatalyst material according to claim 1, wherein the base material has a substantially spherical shape. 4. The photocatalytic material according to claim 1, wherein the base material has an ultraviolet transmittance of 50%.
The photocatalyst material is characterized by the above. 5. The photocatalyst material according to claim 1, wherein the photocatalyst film has an ultraviolet transmittance of 3 or less.
% Or more, the photocatalyst material. 6. The photocatalyst material according to claim 1, wherein the photocatalyst film has an ultraviolet transmittance of 3 or less.
% Or more and less than 70%, a photocatalyst material. 7. The photocatalyst material according to claim 1, wherein the photocatalyst film is TiO ₂ or TiO _2.
And a metal salt layer. 8. The photocatalyst material according to claim 1, wherein the base material is glass. 9. A multi-functional material, wherein the photocatalytic material according to claim 1 is held on the surface of a substrate directly or via a binder layer. 10. The multifunctional material according to claim 9, wherein:
The multifunctional material, wherein the substrate is tile, enamel or porcelain, and the binder layer is a glaze layer or a printing layer. 11. A method for producing the photocatalyst material according to claim 1, wherein the method comprises stirring a base material and a photocatalyst dispersion liquid to form a photocatalyst film on the surface of the base material. ,
A method for producing a photocatalyst material, which comprises firing at 300 ° C. or higher and 900 ° C. or lower. 12. The method for producing a photocatalyst material according to claim 11, wherein the base material is immersed in a photocatalyst aqueous solution of a metal salt of the photocatalyst, followed by photoreduction plating and further washing of excess metal salt. Method for producing photocatalytic material. 13. The method for producing a photocatalyst material according to claim 11 or 12, wherein the mixing ratio of the base material and the photocatalyst dispersion liquid is 1.0 part by weight of the photocatalyst dispersion liquid with respect to 100 parts by weight of the base material. Part or more and 3.6 parts by weight or less, and a method for producing a photocatalyst material. 14. The method for producing a photocatalyst material according to claim 11, wherein the base material is heated in advance to 80 ° C. or higher and 110 ° C. or lower.