Photocatalyst composite and process for producing the same

The present invention relates to a photocatalyst body obtained by adhering photocatalyst particles on a substrate and a method for producing the same.

When the photocatalyst particles are irradiated with light having an energy equal to or higher than the band gap, electrons are generated in the conduction band and holes are generated in the valence band by photoexcitation. The strong reducing power of electrons and the strong oxidizing power of holes generated by this photoexcitation are used for decomposition / purification of organic substances, decomposition of water, and the like. The photocatalyst particles used in such treatment are usually adhered to a substrate larger than the photocatalyst particles in order to prevent scattering and outflow of the photocatalyst particles and facilitate separation from the treatment system. .. To bond the photocatalyst particles on the substrate, the photocatalyst particles are sintered and bonded at a temperature of 400 ° C or higher on the substrate, or the substance that is decomposed by heating to become photocatalyst particles is heated to a temperature of about 400 ° C. A method is adopted in which the particles are sprayed onto the ground particles and adhered to each other. In addition, a method of immobilizing photocatalytic particles using a certain fluorine-based polymer has been proposed. For example, Japanese Patent Application Laid-Open No. 4-284851 describes a method of laminating and pressure-bonding a mixture of photocatalytic particles and a fluorine-based polymer. Further, Japanese Patent Application Laid-Open No. 4-334552 describes a method for heat-sealing photocatalyst particles to a fluorine-based polymer.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 4-284851</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 4-334552</text></patcit></p>

<p> In recent years, there have been attempts to decompose, purify, and sterilize harmful substances, malodorous substances, oils, etc. generated in the daily living environment using photocatalytic particles, and the range of application of photocatalytic particles is expanding. Along with this, there is a demand for a method of adhering photocatalytic particles onto any substrate firmly and for a long period of time without impairing the photocatalytic function. However, the above-mentioned conventional method does not have sufficient adhesive strength such as being easily peeled off by external pressure, and needs to be heated at a high temperature. Therefore, a heat-sensitive substrate such as plastic, an office wall that is difficult to heat, etc. It is difficult to apply when the surface of a building material or various products is used as a substrate, and further, there is a problem that the specific surface area of the photocatalyst particles decreases due to the high temperature heat treatment, which causes a decrease in the photocatalytic function of the photocatalyst particles. .. In addition, special means such as crimping means and heat fusion means are required.</p>

<p> As a result of searching for a method for adhering photocatalytic particles onto any substrate firmly and for a long period of time without impairing the photocatalytic function, (1) the photocatalytic particles were formed using a binder. When adhered onto a substrate, the photocatalyst particles decompose and deteriorate due to the photocatalytic function of the photocatalyst particles, and the photocatalyst particles are detached from the substrate. It can be adhered without detaching onto the photocatalyst, and surprisingly, the photocatalyst of the present invention can obtain a sufficient photocatalytic function. By setting the volume to 5 to 98% of the total amount, it is possible to adhere without deteriorating the photocatalytic function of the obtained photocatalyst. (3) Organic-based fluoropolymers and silicon-based polymers as persistent binders When a binder or an inorganic binder is used, the decomposition / deterioration of the binder due to the photocatalytic function of the photocatalytic particles is extremely small, and the photocatalyst particles can be firmly adhered for a long period of time, particularly. A fluoropolymer containing a copolymer of vinyl ether and / or a vinyl ester and a fluoroolefin as a main component is preferable. (4) The photocatalytic particles have a high photocatalytic function, are chemically stable, and are harmless. A certain titanium oxide is preferable, and (5) as a method of adhering the photocatalyst particles, a method of arranging the photocatalyst particles and the persistent binder on the substrate and then solidifying the photocatalyst particles is convenient, easy and preferable. In particular, a coating composition containing photocatalytic particles, a persistent binder and a solvent is applied or sprayed onto the surface of a substrate of various products, and then solidified to form the surface of various products. The present invention has been completed by finding that the photocatalyst can be used relatively easily and that the photocatalytic function can be easily utilized in each household. That is, the present invention is to provide a photocatalyst body in which photocatalytic particles are adhered to any substrate firmly and for a long period of time without impairing the photocatalytic function.</p>

<figref num="1">It is a figure which showed the transition of the weight loss of the binder in the photocatalyst body by the black light irradiation of the sample A, C of the example and the sample E of a comparative example.</figref>

The present invention is a photocatalyst in which photocatalytic particles are adhered onto a substrate via a persistent binder. In the present invention, the persistently degradable binder is a binder having an extremely slow decomposition rate due to the photocatalytic function of the photocatalytic particles, and the weight reduction of the binder in the photocatalyst body measured by the method described in Examples. Is 10% or less, preferably 5% or less, particularly preferably 3% or less, and most preferably 1% or less. If the weight loss is greater than 10%, the binder is severely decomposed and deteriorated, and the photocatalyst particles are detached extremely frequently, which is not desirable. Examples of the persistent binder of the present invention include silicon compounds such as water glass, colloidal silica, and polyorganosiloxane, phosphates such as zinc phosphate and aluminum phosphate, heavy phosphate, cement, and lime. Examples include cement, frit for spinach, shavings for glass lining, inorganic binders such as plaster, and organic binders such as fluorine-based polymers and silicon-based polymers. Two or more types can be used in combination. In particular, an inorganic binder, a fluorine-based polymer, and a silicon-based polymer are preferable from the viewpoint of adhesive strength. Examples of cement include early-strength cement, ordinary cement, moderate heat cement, sulfate-resistant cement, white cement, oil well cement, geothermal well cement and other portland cement, fly ash cement, high sulfate cement, silica cement, etc. Mixed cement such as blast furnace cement, alumina cement and the like can be used. As the plaster, for example, gypsum plaster, lime plaster, dolomite plaster and the like can be used. Examples of fluoropolymers include polyvinyl fluoride, vinylidene polyfluoride, ethylene trifluoride, polytetrafluoride, ethylene polytetrafluoride-propylene hexafluoride copolymer, ethylene-polytetrafluoroethylene copolymer, and ethylene. -Crystalline fluororesins such as ethylene trifluoride copolymer, ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer, perfluorocyclopolymer, Amorphous fluororesins such as vinyl ether-fluoroolefin copolymers and vinyl ester-fluoroolefin copolymers, and various fluororubbers can be used. In particular, a fluorine-based polymer containing a vinyl ether-fluoroolefin copolymer or a vinyl ester-fluoroolefin copolymer as a main component is preferable because it is less likely to be decomposed and deteriorated and is easy to handle. As the silicone-based polymer, a linear silicone resin, an acrylic-modified silicone resin, various silicone-based rubbers, and the like can be used.

In the present invention, the photocatalytic particles are particles that exhibit a photocatalytic function when irradiated with light having a wavelength equal to or greater than the band gap, such as titanium oxide, zinc oxide, tungsten oxide, iron oxide, and strontium titanate. The known metal compound semiconductors of the above can be used alone or in combination of two or more. In particular, titanium oxide, which has a high photocatalytic function, is chemically stable, and is harmless, is preferable. Further, at least one selected from the group consisting of V, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Pt and Au as the second component inside and / or the surface thereof of the photocatalyst particles. It is preferable to contain a metal and / or a metal compound because it has a higher photocatalytic function. The metal compound includes, for example, metal oxides, hydroxides, oxyhydroxides, sulfates, halides, nitrates, and metal ions. The content of the second component can be appropriately set depending on the substance. Titanium oxide is preferable as the photocatalytic particles containing the metal and / or the metal compound. The content of the photocatalyst particles is preferably 5 to 98% based on the volume of the total amount of the photocatalyst particles and the persistent binder. If the amount of the photocatalyst particles is smaller than the above range, the photocatalyst function of the photocatalyst is likely to be deteriorated, which is not preferable. When cement or gypsum is used as the persistent binder, the content of the photocatalytic particles is preferably 5 to 40%, particularly preferably 5 to 25%. When an inorganic binder or an organic binder other than cement and sekko is used as the persistent binder, the content of the photocatalyst particles is preferably 20 to 98%, more preferably 50 to 98. %, Most preferably 70-98%.

In the present invention, the photocatalytic particles are obtained by a known method. For example, as a method for obtaining titanium oxide, (1) a method of heating and hydrolyzing a titanium compound such as titanyl sulfate, titanium chloride, or titanium alkoxide in the presence of seeds for nucleation, (2) necessary. Correspondingly, in the presence of seeds for nucleation, a method of adding an alkali to a titanium compound such as titanyl sulfate, titanium chloride, or titanium alkoxide to neutralize it, (3) a method of vapor phase oxidation of titanium chloride, titanium alkoxide, etc. (4) There are methods such as firing or hydrothermally treating the titanium oxide obtained by the methods (1) and (2) above, and in particular, titanium oxide obtained by the method (1) or 100 ° C or higher. Titanium oxide obtained by hydrothermal treatment at a temperature is preferable because it has a high photocatalytic function. In the present invention, the titanium oxide includes titanium oxide, titanium hydroxide, hydrated titanium oxide, metatitanic acid, orthotitanium acid, titanium hydroxide and the like, and the crystal type thereof does not matter. Inside and / or on the surface of the photocatalytic particles, at least one metal selected from the group consisting of V, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Pt and Au as a second component and To contain / or a metal compound, a method of adding and adsorbing the metal and / or the metal compound when producing the photocatalytic particles, adding the metal and / or the metal compound after producing the photocatalyst particles. , Adsorption and heating as needed, or reduction as needed can be used.

In the present invention, as the substrate, an article made of an inorganic material such as ceramics and glass, an article made of an organic material such as plastic, rubber, wood and paper, an article made of a metal such as aluminum, and an article made of a metal material such as an alloy such as steel are used. Can be done. The size and shape of the substrate are not particularly limited. It can also be used for painted articles.

In the present invention, it is preferable to bond the photocatalyst particles and the adsorbent onto the substrate via a persistent binder because it can also have an action of adsorbing the substance to be treated. As the adsorbent, a general adsorbent can be used, and for example, activated carbon, zeolite, silica gel, or the like can be used.

Further, in the present invention, a first layer made of a binder and containing no photocatalyst particles is provided on the substrate, and further, the persistent binder and photocatalyst particles are formed on the first layer. A second layer can be provided. By providing the first layer containing no photocatalyst particles, the bond between the substrate and the second layer containing the photocatalyst particles is strengthened, and the photocatalyst particles are placed on the substrate more firmly and for a longer period of time. Can be adhered over. As such a binder, an organic binder is preferable, and the persistent binder described above is more preferable. Further, it is preferable that the first layer contains inorganic particles having no photocatalytic function as a filler. As such inorganic particles, titanium oxide, silicon oxide, aluminum oxide, magnesium oxide, etc., which have been surface-treated with silicon oxide, aluminum oxide, zirconium oxide, or the like so as not to have a photocatalytic function can be used. ..

In order to produce the photocatalyst of the present invention, the photocatalytic particles and the persistent binder are placed on at least a part of the substrate, then solidified, and the photocatalyst particles are solidified on the substrate via the persistent binder. Adhere the photocatalytic particles. In the present invention, in particular, the photocatalyst particles and the persistently decomposable binder are dispersed in a solvent to obtain a coating composition, and then the coating composition is applied or sprayed onto a substrate to obtain the photocatalyst particles and the persistently decomposable. It is preferable to place the sex binder on at least a part of the substrate. As the solvent, an organic solvent such as water, toluene, or alcohol can be used. As the persistent binder to be contained in the coating composition, the above-mentioned ones can be used, but those which are soluble in the solvent contained are preferable. In the present invention, the above-mentioned fluorine-based polymer and / or silicon-based polymer is preferable as the persistently decomposable binder contained in the coating composition. The amount of photocatalytic particles in the coating composition is 5 to 98%, preferably 20 to 98%, more preferably 50 to 98%, most preferably 50 to 98% based on the volume of the total amount of the photocatalytic particles and the persistent binder. It is preferably 70 to 98%. A cross-linking agent, a dispersant, a filler and the like can be blended in the coating composition. As the cross-linking agent, an ordinary cross-linking agent such as isocyanate-based or melamine-based can be used, and as the dispersant, a coupling agent or the like can be used. In particular, when the content of the photocatalyst particles in the coating composition is 40 to 98% based on the volume of the total amount of the photocatalyst particles and the persistent binder, the coating composition is coupled. It is preferable to mix the agent. The amount of this coupling agent added is preferably 5 to 50%, more preferably 7 to 30%.

To apply or spray the coating composition on the substrate, for example, the usual impregnation method, dip coating method, spinner coating method, blade coating method, roller coating method, wire bar coating method, reverse roll coating method, etc. The photocatalytic particles and the persistent binder can be placed on at least a part of the substrate by coating by a method or by spraying by a usual method such as a spray coating method. Before applying or spraying the coating composition on the substrate, organic binders such as acrylic resin, epoxy resin, polyester resin, melamine resin, urethane resin, and alkyd resin may be used as necessary. A degradable binder is applied or sprayed on the substrate to form a first layer containing no photocatalyst particles, and further, the coating composition is applied or sprayed on the first layer to make the photocatalyst particles difficult. A second layer made of a degradable binder can be provided.

After coating or spraying as described above, it is solidified to obtain the photocatalyst of the present invention. The solidification can be carried out by drying, irradiating with ultraviolet rays, heating, cooling, or using a cross-linking agent, but the temperature of solidification is lower than 400 ° C., preferably. Perform at room temperature to 200 ° C. In this case, if the temperature is higher than 400 ° C, the binder is thermally deteriorated and the photocatalytic particles are easily detached, which is not preferable. In the present invention, a method of solidifying using a cross-linking agent such as isocyanate-based or melamine-based is preferable.

The photocatalyst of the present invention decomposes and purifies harmful substances, malodorous substances, oils, etc. existing around the photocatalyst body by irradiating the photocatalyst with light having a wavelength equal to or higher than the band gap of the photocatalyst particles. , Can be sterilized. Examples of the light to be irradiated include light containing ultraviolet rays, and for example, light such as sunlight, a fluorescent lamp, a black light, a halogen lamp, a xenon flash lamp, and a mercury lamp can be used. In particular, light containing near ultraviolet rays of 300 to 400 nm is preferable. The amount of light irradiation and the irradiation time can be appropriately set depending on the amount of the substance to be processed.

Example 1 Sodium hydroxide was added to acidic titania sol (manufactured by Ishihara Sangyo Co., Ltd., CS-N) obtained by heating and hydrolyzing titanyl sulfate to adjust the pH to 7, and then filtration and washing were performed. Then, water was added to the obtained titanium oxide wet cake, and TiO₂A slurry of 100 g / l was prepared in terms of. Sodium hydroxide was added to this slurry to adjust the pH to 10, and then hydrothermal treatment was performed in an autoclave at a temperature of 150 ° C. for 3 hours. Next, nitric acid was added to the slurry after hydrothermal treatment to neutralize it to pH 7, filtered and washed with water, and then dried at a temperature of 110 ° C. for 3 hours to obtain titanium oxide. Next, the mixture having the composition shown below was shaken with a paint shaker for 3 hours to sufficiently mix and disperse to obtain a paint composition. The following Lumiflon LF200C is a fluorine-based polymer containing a copolymer of vinyl ether and fluoroolefin as a main component. Titanium oxide 9.80g Fluorine-based polymer (Asahi Glass Co., Ltd., Lumiflon LF200C) 0.80g Isocyanate curing agent 0.16g Titanium coupling agent (Ajinomoto Co., Inc., Plain Act 338X) 1.00g toluene 23.60ml 20 cm of the paint composition of the above composition²After coating on the glass plate of the above, it was dried at a temperature of 120 ° C. for 20 minutes to obtain a photocatalyst (Sample A) of the present invention. The titanium oxide content of this sample A was 90% on a volume basis with respect to the total amount of the titanium oxide and the persistent binder.

Example 2 Titanium oxide having the same composition as that used in Example 1 was sufficiently mixed by shaking with a paint shaker for 3 hours as a mixture having the composition shown below, and dispersed to obtain a coating composition. Titanium oxide 7.64g Fluorine-based polymer (Asahi Glass Co., Ltd., Lumiflon LF200C) 2.36g Isocyanate-based curing agent 0.47g Titanium coupling agent (Ajinomoto Co., Inc., Plain Act 338X) 0.76g Toluene 22.50 ml 20 cm of the paint composition of the above composition²After coating on the glass plate of the above, it was dried at a temperature of 120 ° C. for 20 minutes to obtain a photocatalyst (Sample B) of the present invention. The titanium oxide content of this sample B was 70% on a volume basis with respect to the total amount of the titanium oxide and the persistent binder.

Example 3 Titanium oxide having the same composition as that used in Example 1 was sufficiently mixed by shaking with a paint shaker for 1 hour as a mixture having the composition shown below, and dispersed to obtain a coating composition. Titanium oxide 9.8g Polyorganosiloxane-based inorganic binder (Made by Nippon Synthetic Rubber Co., Ltd., 3: 1 mixture of T2202A and T2202B) 2.7g Isopropyl alcohol 21.5ml 20 cm of the paint composition of the above composition²After coating on the glass plate of the above, it was dried at 180 ° C for 10 minutes to obtain the photocatalyst (Sample C) of the present invention. The titanium oxide content of this sample C was 90% on a volume basis with respect to the total amount of the titanium oxide and the persistent binder.

Example 4 Sodium hydroxide was added to acidic titania sol (manufactured by Ishihara Sangyo Co., Ltd., CS-N) obtained by heating and hydrolyzing titanyl sulfate to adjust the pH to 7, and then filtration and washing were performed. Then, the obtained titanium oxide wet cake was dried at a temperature of 110 ° C. for 3 hours to obtain titanium oxide. Next, as a mixture having the composition shown below, the mixture was sufficiently mixed by shaking with a paint shaker for 3 hours and dispersed to obtain a paint composition. Titanium oxide 7.0g Polyorganosiloxane-based inorganic binder (Made by Nippon Synthetic Rubber Co., Ltd., 3: 1 mixture of T2202A and T2202B) 4.3g Isopropyl alcohol 22.5 ml 20 cm of the paint composition of the above composition²After coating on the glass plate of the above, it was dried at 180 ° C. for 10 minutes to obtain the photocatalyst (Sample D) of the present invention. The titanium oxide content of this sample D was 80% on a volume basis with respect to the total amount of the titanium oxide and the persistent binder.

Comparative example 1 Titanium oxide having the same composition as that used in Example 1 was sufficiently mixed by shaking with a paint shaker for 1 hour as a mixture having the composition shown below, and dispersed to obtain a coating composition. Titanium oxide 9.8g Vinyl Acetate-Acrylic Copolymer (Boncoat 6290, manufactured by Dainippon Ink and Chemicals Co., Ltd.) 0.7g Water 24.8ml 20 cm of the paint composition of the above composition²After coating on the glass plate of No. 1, it was dried at 120 ° C. for 10 minutes to obtain a photocatalyst (Sample E). The titanium oxide content of this sample E was 90% on a volume basis with respect to the total amount of the titanium oxide and the binder.

Using the photocatalysts (Samples A to E) obtained in the above Examples and Comparative Examples, the ultraviolet light intensity was 7 mW / cm on the surface of each sample.²It was irradiated with black light so that it would be, and continued for 5 hours. The weight loss of the binder in the photocatalyst before and after irradiation with black light was measured. As a result, no weight loss was observed in the samples A to D of the present invention, and the binder was not decomposed. However, Sample E of Comparative Example, which did not use a persistent binder, had a weight loss of 85%, and most of the binder was decomposed by the photocatalytic function of titanium oxide. Moreover, yellowing was observed in Sample E, and titanium oxide was partially exfoliated. FIG. 1 shows the transition of the weight loss of the binder in the photocatalyst due to the black light irradiation of Samples A and C of Example and Sample E of Comparative Example. In Samples A and B of Examples 1 and 2, a coupling agent is blended, and the coupling agent is adsorbed on the surface of the photocatalyst particles and is between the persistent binder and the photocatalyst particles. Since the photocatalytic particles do not come into direct contact with the binder, the binder is not easily decomposed.

Next, the samples A to D of the present invention were placed separately in a 3 liter glass container, and then acetaldehyde, which is a malodorous component, was added to a concentration of 90 ppm to seal the glass container. Next, the ultraviolet light intensity is 14 mW / cm on the surface of each sample.²The mercury lamp was irradiated so as to be, and it continued for 60 minutes. After irradiation, the concentration of acetaldehyde in the glass container was measured. The results are shown in Table 1. In samples A to D, acetaldehyde was efficiently decomposed by the photocatalytic function of titanium oxide.

<tables num="1"><img file="JP4695700B2_D0001.tif" /></tables>

Example 5 Sodium hydroxide is added to acidic titania sol (manufactured by Ishihara Sangyo Co., Ltd., CS-C) obtained by heating and hydrolyzing titanyl sulfate to adjust the pH to 7, and then filtered, washed, dried, and then pulverized to obtain titanium oxide. Obtained. This titanium oxide 0.2g, white cement (manufactured by Onoda Cement Co., Ltd.) 0.8g, and water 0.7g are mixed and the area is 50cm.²The whole amount was applied to the glass plate of No. 1 and dried at room temperature to obtain a photocatalyst (Sample F). The titanium oxide content of this sample F was 17% on a volume basis with respect to the total amount of the titanium oxide and the persistent binder.

Example 6 The photocatalyst (Sample G) of the present invention was obtained in the same manner as in Example 5 except that 0.8 g of Denka high alumina cement (manufactured by Denki Kagaku Kogyo Co., Ltd., Hi) was used instead of the white cement in Example 5. It was. The titanium oxide content of this sample G was 17% on a volume basis with respect to the total amount of the titanium oxide and the persistent binder.

Comparative example 2 1.0 g of white cement used in Example 5 and 0.7 g of water are mixed, and the area is 50 cm.²The whole amount was applied to the glass plate of No. 1 and dried at room temperature to obtain Sample H.

Comparative example 3 1.0 g of Denka high alumina cement (Hi) used in Example 6 and 0.7 g of water are mixed, and the area is 50 cm.²The whole amount was applied to the glass plate of No. 1 and dried at room temperature to obtain Sample I.

Samples F to I obtained in the above Examples and Comparative Examples were placed in containers having a capacity of 4 liters, respectively, and then nitric oxide standard gas was injected. Next, the ultraviolet light intensity is 1 mW / cm on the surface of each sample.²Irradiate the light of black light so that it becomes, and NO of each container_xNO concentration of gas_xIt was measured over time with a detector tube (11L manufactured by Gastec). The results are shown in Table 2. Samples F and G of Examples 5 and 6 are NO_xWhile the gas concentration is significantly reduced, NO in Samples H and I of Comparative Examples 2 and 3._xIt can be seen that the gas concentration has hardly changed. From this, it was clarified that the photocatalyst of the present invention is effective in oxidizing and removing nitrogen monoxide. When the weight loss of the cement in the samples F and G was measured by the above method, no weight loss was observed and the cement was not decomposed.

<tables num="2"><img file="JP4695700B2_D0002.tif" /></tables>

Example 7 The coating composition obtained according to the method of Example 1 has an area of 100 cm.²The entire amount was applied to the transparent acrylic plate of No. 1 and dried at a temperature of 120 ° C. for 20 minutes to obtain the photocatalyst (Sample J) of the present invention. The titanium oxide content of this sample J was 90% on a volume basis with respect to the total amount of the titanium oxide and the persistent binder.

Comparative example 4 The transparent acrylic plate used in Example 7 was used as sample K.

Samples J and K obtained in the above Example and Comparative Example were attached to the inner wall of a water tank having a capacity of 50 liters, respectively. 45 liters of water and 20 goldfish (goldfish) were placed in this aquarium, and the light of two 20 W fluorescent lamps was irradiated from the outside of the aquarium. At the time of breeding for 2 weeks, adhesion of algae was observed on the surface of sample K of Comparative Example 4, whereas no adhesion of algae was observed on the surface of sample J of Example 7. This is because even if algae adhere to the surface of Sample J of Example 7, the algae are immediately decomposed by the photocatalytic function. When the weight loss of the fluorine-based polymer in Sample J was measured by the above method, no weight loss was observed, and the fluorine-based polymer was not decomposed.

Example 8 In Example 7, the mixture having the composition shown below was shaken with a paint shaker for 1 hour to sufficiently mix, and the paint composition obtained by dispersing the mixture was put on a transparent acrylic plate with a spin coater (1000 r.pm × 10 seconds). It was treated in the same manner as in Example 7 except that a substrate having a first layer containing no photocatalyst particles, which was made of a persistent binder and was provided on the transparent acrylic plate, was used. The photocatalyst (Sample L) of the present invention was obtained. The content of titanium oxide, which is a photocatalytic particle in the second layer of this sample L, was 90% on a volume basis with respect to the total amount of the titanium oxide and the persistent binder. Titanium oxide without photocatalytic function (CR-90, manufactured by Ishihara Sangyo Co., Ltd.) 3.3g Fluorine-based polymer (Asahi Glass Co., Ltd., Lumiflon LF200C) 5.5g Isocyanate curing agent 1.1g Toluene 20.7ml

When the weight loss of the binder used for the sample L was measured by the above method, no weight change was observed in the sample L of the present invention, the binder was not decomposed, and the titanium oxide photocatalyst particles were not peeled off from the substrate. .. Moreover, as a result of examining the film strength of the sample L of Example 8 with the pencil hardness, it was 3H, and it was found that the photocatalytic particles of titanium oxide were firmly adhered. Furthermore, this sample L is placed in a water stream and the ultraviolet light intensity on the surface is 2 mW / cm.²When the particles were irradiated with black light so as to be, and continued for 3 weeks, the titanium oxide photocatalyst particles did not peel off from the substrate.

Example 9 A photocatalyst (Sample M) of the present invention was obtained in the same manner as in Example 1 except that titanium oxide carrying a zinc compound was used instead of titanium oxide in Example 1. The content of the titanium oxide photocatalyst particles carrying the zinc compound in the sample M was 90% based on the volume of the total amount of the photocatalyst particles and the persistent binder. Titanium oxide carrying a zinc compound was prepared as follows. Water and sodium hydroxide were added to a titanium oxide slurry obtained by heating and hydrolyzing titanyl sulfate to a pH of 10 and TiO.₂It was converted into a slurry of 100 g / l. This slurry was hydroheat-treated in an autoclave at a temperature of 150 ° C. for 5 hours, neutralized with nitric acid, filtered, and washed with water. Water was added to the obtained titanium oxide wet cake, and TiO₂After preparing a slurry of 100 g / l, hydrochloric acid was added to adjust the pH of the slurry to 4. To 1 liter of this slurry, 7.2 ml of a 1 mol / l zinc chloride aqueous solution was added dropwise with stirring, then neutralized with 2N sodium hydroxide, filtered and washed with water, and then at a temperature of 120 ° C. for 16 hours. It was dried and pulverized to obtain titanium oxide carrying a zinc compound. This titanium oxide contains ZnO: TiO₂A = 1: 99 amount of zinc compound was contained on the surface of the titanium oxide.

Example 10 A photocatalyst (Sample N) of the present invention was obtained in the same manner as in Example 1 except that titanium oxide carrying an iron compound was used instead of titanium oxide in Example 1. The content of the titanium oxide photocatalyst particles carrying the iron compound in this sample N was 90% on a volume basis with respect to the total amount of the photocatalyst particles and the persistent binder. Titanium oxide carrying an iron compound was prepared as follows. 10 g of titanium oxide obtained by heating and hydrolyzing titanyl sulfate is TiO₂A slurry of 100 g / l was prepared in terms of. Iron (FeCl) chloride in this slurry₃ 6H₂After adding 2.9 ml of a 5 g / l aqueous solution of O) and stirring for 1 hour, dilute ammonia water was added to adjust the pH to 7. Then, the slurry was stirred for 1 hour, filtered, washed with water, and dried at a temperature of 110 ° C. for 3 hours to obtain titanium oxide carrying an iron compound. Fe / TiO is used for this titanium oxide.₂= 300 ppm of iron compound was contained on the surface of the titanium oxide.

Example 11 The photocatalyst (Sample O) of the present invention was obtained in the same manner as in Example 10 except that the concentration of the iron chloride aqueous solution was set to 50 g / l in Example 10. The content of the titanium oxide photocatalyst particles carrying the iron compound in this sample O was 90% on a volume basis with respect to the total amount of the photocatalyst particles and the persistent binder. Fe / TiO is used for this titanium oxide.₂= 3000ppm of iron compound was contained on the surface of the titanium oxide.

Example 12 The photocatalyst (Sample P) of the present invention was obtained by treating in the same manner as in Example 1 except that the coating composition contained 8.9 g of titanium oxide and 0.5 g of activated charcoal as an adsorbent in Example 1. The total content of titanium oxide and activated carbon in this sample P was 90% on a volume basis with respect to the total amount of titanium oxide, activated carbon and the persistent binder.

Example 13 In Example 12, the photocatalyst (Sample Q) of the present invention was obtained by treating in the same manner as in Example 12 except that 0.8 g of zeolite was used instead of activated carbon. The total content of titanium oxide and zeolite in this sample Q was 90% on a volume basis with respect to the total amount of titanium oxide, zeolite and the persistent binder.

When the weight loss of the binder used for the samples L to Q was measured by the above method, no weight change was observed in the samples L to Q of the present invention, the binder was not decomposed, and the titanium oxide photocatalyst particles were the substrate. Did not come off from.

Next, the samples A, N, and O of the present invention were placed separately in a 0.8 liter glass container, and then acetaldehyde, which is a malodorous component, was added to a concentration of about 100 ppm to seal the glass container. Next, after leaving it for 30 minutes without irradiation, the ultraviolet light intensity is 1 mW / cm on the surface of each sample.²It was irradiated with black light so that it would be, and continued for 60 minutes. After irradiation, the concentration of acetaldehyde in the glass container was measured. The results are shown in Table 3. In samples A, N and O, acetaldehyde was efficiently decomposed by the photocatalytic function of titanium oxide.

<tables num="3"><img file="JP4695700B2_D0003.tif" /></tables>

Next, the samples M, P, and Q of the present invention were placed separately in a 0.8 liter glass container, and then methyl mercaptan, which is a malodorous component, was added to a concentration of about 500 ppm to seal the glass container. Next, after leaving it for 2 hours without irradiation, the ultraviolet light intensity is 1 mW / cm on the surface of each sample.²It was irradiated with black light so that it would be, and continued for 60 minutes. After irradiation, the concentration of methyl mercaptan in the glass container was measured. The results are shown in Table 4. Samples M, P and Q were able to efficiently remove methyl mercaptan due to the photocatalytic function of titanium oxide.

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In the above test, the concentration of methyl mercaptan after being left without irradiation with ultraviolet rays for 2 hours was 250 ppm, respectively, and the concentration of methyl mercaptan after being left without irradiation with ultraviolet rays for another 1 hour was determined. When the samples M and Q of Examples 9 and 13 were used, the concentration was 240 ppm, and when the samples P of Example 12 were used, the concentration was 220 ppm.

In the photocatalyst of the present invention, photocatalytic particles are adhered onto a substrate via a persistent binder, and the photocatalytic function of the photocatalyst particles causes extremely little decomposition and deterioration of the binder, and the photocatalyst particles can be used as any substrate. On top of that, it can be adhered firmly and for a long period of time without impairing its photocatalytic function. Since the photocatalytic function of the photocatalyst of the present invention can be used to quickly and efficiently remove harmful substances, malodorous substances, oils, bacteria, actinomycetes, fungi, algae, etc., it can be removed not only for industrial use but also for general households. It is extremely useful as a deodorizing body, a sterilizing body, etc. Further, the photocatalyst of the present invention is extremely useful industrially because it can be used for a long period of time, has high safety, has a wide range of applicable harmful substances, and does not pollute the environment even if it is discarded. .. When a fluoropolymer is used as a persistent binder in producing the photocatalyst of the present invention, dust and dirt are unlikely to adhere to the surface of the photocatalyst because the adhesive strength of the fluoropolymer itself is weak. That is, a preferable photocatalyst can be produced. Further, the method for producing a photocatalyst of the present invention is a useful method such that a photocatalyst of any material such as plastic can be used as a substrate, and a photocatalyst of stable quality can be easily and easily produced. Further, the coating composition of the present invention can be applied or sprayed on a substrate of any shape or a necessary part of the substrate, and its photocatalytic function can be easily utilized, which is particularly useful for general household use. Is.