JPH11124546A - Paint composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a photocatalytic particle to adhere strongly to any substrate over a long period of time without losing its photocatalytic ability and with extremely little degradation and deterioration of the binder caused by the photocatalytic particle. SOLUTION: A photocatalytic body is prepared by attaching a photocatalytic particle onto a substrate through a difficulty-degraded binder such as an inorganic binder such as a silicon compound such as a water glass, a colloidal silica or a polyorganosiloxane, a phosphate such as zinc phosphate or aluminum phosphate, a biphosphate or cement or an organic binder such as a fluorine polymer or a silicone polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst formed by adhering photocatalyst particles on a substrate and a method for producing the same.

[0002]

2. Description of the Related Art When photocatalytic particles are irradiated with light having a wavelength having energy equal to or greater than the band gap, photoexcitation generates electrons in a conduction band and holes in a valence band. The strong reducing power of the electrons and the strong oxidizing power of the holes generated by the photoexcitation are used for decomposing and purifying organic substances, decomposing water, and the like. The photocatalyst particles used for such treatment usually have the photocatalyst particles adhered to a substrate larger than the photocatalyst particles to prevent scattering and outflow of the photocatalyst particles and to facilitate separation from the processing system. . In order to adhere the photocatalyst particles to the substrate, the substrate is formed by sintering the photocatalyst particles on the substrate at a temperature of 400 ° C. or higher and bonding the material, or by heating and decomposing the photocatalytic particles to a temperature of about 400 ° C. A method of spraying on and bonding them is adopted. Also,
There has been proposed a method of immobilizing photocatalyst particles using a certain kind of fluorine-based polymer. For example, Japanese Patent Laid-Open No. 4-284
No. 851 describes a method of laminating and pressing a mixture of photocatalyst particles and a fluoropolymer. Also,
Japanese Patent Application Laid-Open No. 4-334552 discloses a method of heat-fusing photocatalyst particles to a fluoropolymer.

[0003]

In recent years, there have been attempts to use photocatalytic particles to decompose, purify, or sterilize harmful substances, odorous substances, oils, and the like generated in daily living environments.
The application range of photocatalyst particles is expanding. Accordingly, there is a demand for a method for bonding photocatalyst particles to any substrate firmly and for a long period of time without impairing its photocatalytic function. However, in the method of the prior art described above, the adhesive strength is not sufficient, such as easy peeling due to external pressure, and since it is necessary to heat at a high temperature, heat-sensitive substrates such as plastics, hard-to-heat office walls, etc. It is difficult to apply when the surface of a building material or various products is used as a base, and furthermore, there is a problem that the specific surface area of the photocatalyst particles is reduced due to the high-temperature heat treatment, so that the photocatalytic function of the photocatalyst particles is reduced. . In addition, special means such as pressure bonding means and heat fusion means may be required.

[0004]

Means for Solving the Problems The present inventors have searched for a method for bonding photocatalyst particles firmly over a long period of time without impairing the photocatalytic function on any substrate, and as a result, (1) When the photocatalyst particles are adhered to the substrate using the binder, the binder is decomposed and degraded by the photocatalytic function of the photocatalyst particles, and the photocatalyst particles are detached from the substrate. By using, the photocatalyst particles can be adhered to any substrate without being detached.
Surprisingly, the photocatalyst of the present invention provides a sufficient photocatalytic function. (2) The photocatalyst particles are 5 to 98% by volume based on the total amount of the photocatalyst particles and the hardly decomposable binder. By this, it is possible to adhere without deteriorating the photocatalytic function of the obtained photocatalyst. (3) When an organic binder or an inorganic binder such as a fluorine-based polymer or a silicon-based polymer is used as the hardly decomposable binder. The decomposition and degradation of the binder due to the photocatalytic function of the photocatalyst particles is extremely small.
That the photocatalyst particles can be adhered firmly and over a long period of time, in particular that a fluorine-based polymer containing a copolymer of vinyl ether and / or vinyl ester and fluoroolefin as a main component is preferable;
(4) As the photocatalyst particles, titanium oxide which has high photocatalytic function, is chemically stable and is harmless is preferable. (5) As a method of bonding the photocatalyst particles, the photocatalyst particles are hardly decomposed. Disposing a conductive binder on a substrate,
Then, the method of solidifying is simple, easy, and preferable. In particular, a coating composition containing photocatalyst particles, a hardly decomposable binder, and a solvent is applied or sprayed on the surface of a substrate such as various products. By arranging and solidifying, the surface of various products can be relatively easily made into a photocatalyst, and the photocatalytic function can be easily utilized in each household, and the present invention has been found. completed.

[0005] That is, the present invention provides a method in which photocatalyst particles are firmly formed on any substrate without impairing the photocatalytic function.
Another object of the present invention is to provide a photocatalyst that is adhered over a long period of time.

The present invention is a photocatalyst in which photocatalyst particles are adhered to a substrate via a hardly decomposable binder. In the present invention, the hard-to-decompose binder is a binder having a very low rate of decomposition due to the photocatalytic function of the photocatalyst particles, and the weight loss of the binder in the photocatalyst measured by the method described in Examples. Is 10% or less, preferably 5% or less, particularly preferably 3%
Or less, most preferably 1% or less. If the weight loss is more than 10%, the binder is undesirably decomposed and deteriorated severely, and the photocatalyst particles are extremely detached. Examples of the hardly decomposable binder of the present invention include water glass, colloidal silica, silicon compounds such as polyorganosiloxane, zinc phosphate, phosphates such as aluminum phosphate, heavy phosphates, cement, lime, Gypsum, enamel frit, glaze for glass lining, inorganic binders such as plaster, fluorine-based polymers, organic binders such as silicon-based polymers, and the like, these binders may be used alone or Two or more 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 portland cement such as early-strength cement, ordinary cement, moderate heat cement, sulfate resistant cement, white (white) cement, oil well cement, geothermal well cement, fly ash cement, high sulfate cement, silica cement, Blended 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 the fluorine-based polymer include polyvinyl fluoride, polyvinylidene fluoride, polychlorinated ethylene trifluoride, polytetrafluoroethylene, polytetrafluoroethylene-hexafluoropropylene copolymer, ethylene-polytetrafluoroethylene copolymer, ethylene -Crystalline fluororesin such as ethylene chloride trifluoride copolymer, ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer, amorphous fluororesin such as perfluorocyclopolymer, vinyl ether-fluoroolefin copolymer, vinyl ester-fluoroolefin copolymer,
Various fluorine rubbers and the like can be used. Especially,
Fluoropolymers containing a vinyl ether-fluoroolefin copolymer or a vinyl ester-fluoroolefin copolymer as a main component are preferred because they are less likely to decompose and deteriorate and are easy to handle. Silicone polymers include straight-chain silicone resin, acrylic-modified silicone resin,
Various silicone rubbers and the like can be used.

In the present invention, the photocatalyst particles are particles that exhibit a photocatalytic function when irradiated with light having a wavelength having energy equal to or greater than the band gap, and include titanium oxide, zinc oxide, tungsten oxide, iron oxide, and titanium oxide. Known metal compound semiconductors such as strontium acid 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, as a second component, V, Fe, Co, Ni, Cu, Zn, Ru, Rh,
It is preferable to contain at least one kind of metal and / or metal compound selected from the group consisting of Pd, Ag, Pt, and Au, because they have a higher photocatalytic function. Examples of the metal compound include metal oxides, hydroxides, oxyhydroxides, sulfates, halides, nitrates, and metal ions. The content of the second component can be appropriately set depending on the substance. Said metal and / or
Alternatively, titanium oxide is preferable as the photocatalyst particles containing a metal compound. The content of the photocatalyst particles is 5 to 5 based on the volume based on the total amount of the photocatalyst particles and the hardly decomposable binder.
98% is preferred. If the amount of the photocatalyst particles is smaller than the above range, the photocatalytic function of the photocatalyst body is likely to decrease, which is not preferable. When cement or gypsum is used as the hardly decomposable binder, the content of the photocatalyst particles is preferably 5 to 40%, particularly preferably 5 to 25%. When an inorganic binder or an organic binder other than cement and gypsum is used as the hardly decomposable 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 photocatalyst particles are obtained by a known method. For example, as a method for obtaining titanium oxide,
A method in which a titanium compound such as titanyl sulfate, titanium chloride, or titanium alkoxide is heated and hydrolyzed in the presence of seeds for nucleation, if necessary. Titanium, titanium alkoxide and other titanium compounds are neutralized by adding an alkali, titanium chloride and titanium alkoxide are vapor-phase oxidized, and the titanium oxide obtained by the above method is calcined or hydrothermally treated. There are, in particular,
Titanium oxide obtained by the above method or titanium oxide obtained by hydrothermal treatment at a temperature of 100 ° C. or higher is preferable because of its high photocatalytic function. In the present invention, the titanium oxide includes, in addition to titanium oxide, those commonly referred to as titanium oxide hydrous, hydrated titanium oxide, metatitanic acid, orthotitanic acid, titanium hydroxide and the like, and the crystal type is not limited. V, Fe, Co, Ni, Cu, Zn, R, as a second component, inside and / or on the surface of the photocatalyst particles.
In order to contain at least one metal and / or metal compound selected from the group consisting of u, Rh, Pd, Ag, Pt and Au, the metal and / or the metal compound is added when producing the photocatalyst particles. And a method of adding the metal and / or the metal compound after producing the photocatalyst particles, adsorbing the resultant, and heating or reducing as necessary.

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

In the present invention, it is preferable that the photocatalyst particles and the adsorbent are adhered to the substrate via the hardly decomposable binder because they can also have the function of adsorbing the substance to be treated. As the adsorbent, a general adsorbent can be used, and for example, activated carbon, zeolite, silica gel, and the like can be used.

Furthermore, in the present invention, a first layer comprising a binder and not containing photocatalyst particles is provided on a substrate,
Further, a second layer comprising a hardly decomposable binder and photocatalyst particles can be provided on the first layer. By providing the first layer containing no photocatalyst particles, the connection between the substrate and the second layer containing the photocatalyst particles becomes stronger,
The photocatalyst particles can be more firmly adhered to the substrate over a longer period of time. As such a binder, an organic binder is preferable, and the above-mentioned hardly decomposable binder 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 subjected to surface treatment with silicon oxide, aluminum oxide, zirconium oxide, or the like so as not to have a photocatalytic function, can be used. .

To produce the photocatalyst of the present invention, the photocatalyst particles and the hard-to-decompose binder are arranged on at least a part of the substrate, and then solidified to form a hard-to-decompose binder on the base. To adhere the photocatalyst particles. In the present invention, in particular, the photocatalyst particles and the hardly decomposable binder are dispersed in a solvent to form a coating composition, and then the coating composition is applied or sprayed on a substrate to form the photocatalytic particles and the hardly decomposable binder. It is preferable to dispose the conductive binder on at least a part of the substrate. As the solvent, water, an organic solvent such as toluene or alcohol can be used. As the hardly decomposable binder to be contained in the coating composition, those described above can be used, but those which are soluble in the contained solvent are preferable. In the present invention, the above-mentioned fluorine-based polymer and / or silicon-based polymer are preferable as the hardly decomposable binder contained in the coating composition. The amount of photocatalyst particles in the coating composition is
It is 5 to 98%, preferably 20 to 98%, more preferably 50 to 98%, and most preferably 70 to 98% by volume based on the total amount of the photocatalyst particles and the hardly decomposable binder. The coating composition may contain a crosslinking agent, a dispersant, a filler and the like. As a cross-linking agent, a normal cross-linking agent such as an isocyanate-based or melamine-based one can be used, and as a dispersant, a coupling agent or the like can be used. In particular, when the content of the photocatalyst particles in the coating composition is set to 40 to 98% by volume based on the total amount of the photocatalyst particles and the hard-to-decompose binder, the coupling in the coating composition is made. It is preferable to add an agent. The amount of the coupling agent is preferably 5 to 50%, more preferably 7 to 50%.
３０30%.

For applying or spraying a coating composition on a substrate, for example, impregnation, dip coating, spinner coating, blade coating, roller coating, wire bar coating, reverse roll coating, etc. The photocatalyst particles and the hard-to-decompose binder can be arranged on at least a part of the substrate by applying by a usual method of the above or spraying by a usual method such as a spray coating method. Before applying or spraying the coating composition on the substrate, if necessary, acrylic resin,
Epoxy resin, polyester resin, melamine resin, urethane resin, organic binder such as alkyd resin or hardly decomposable binder is applied or sprayed on the substrate to form a first layer containing no photocatalyst particles, On the first layer, a second layer composed of photocatalyst particles and a hardly decomposable binder can be provided by applying or spraying the coating composition.

After being applied or sprayed as described above, it is solidified to obtain the photocatalyst of the present invention. The solidification can be performed by a method of drying, irradiating ultraviolet rays, heating, cooling, or using a crosslinking agent, and the solidification temperature is lower than 400 ° C., preferably room temperature. Performed at a temperature of ℃ 200 ° C. In this case, if the temperature is higher than 400 ° C., the binder is thermally degraded, and the photocatalyst particles are easily desorbed. In the present invention, a method of using an isocyanate-based or melamine-based cross-linking agent for solidification is preferable.

The photocatalyst of the present invention is irradiated with light having a wavelength having energy equal to or larger than the band gap of the photocatalyst particles to decompose harmful substances, malodorous substances, oils and the like existing therearound. Can be purified and sterilized. Examples of the light to be irradiated include light containing ultraviolet light, for example, sunlight, a fluorescent light,
Light from a black light, a halogen lamp, a xenon flash lamp, a mercury lamp, or the like can be used. Especially,
Light containing near-ultraviolet light of 300 to 400 nm is preferred. The light irradiation amount, irradiation time, and the like can be set as appropriate depending on the amount of the substance to be treated.

[0016]

Example 1 An acidic titania sol (CS-N, manufactured by Ishihara Sangyo Co., Ltd.) obtained by heating and hydrolyzing titanyl sulfate was adjusted to pH 7 by adding sodium hydroxide, followed by filtration and washing. Next, water was added to the obtained titanium oxide wet cake, and TiO ₂
A slurry of 100 g / l was prepared. The slurry was adjusted to pH 10 by adding sodium hydroxide, and then subjected to hydrothermal treatment at 150 ° C. for 3 hours in an autoclave. Next, nitric acid was added to the slurry after the hydrothermal treatment to neutralize the pH to 7, filtration, and washing with water were performed.
At a temperature of 3 hours to obtain titanium oxide. Next, a mixture having the following composition was shaken with a paint shaker for 3 hours to be sufficiently mixed and dispersed to obtain a coating composition. The following Lumiflon LF200C is a fluorine-based polymer containing a copolymer of vinyl ether and fluoroolefin as a main component. Titanium oxide 9.80 g Fluoropolymer (Lumiflon LF200C, manufactured by Asahi Glass Co.) 0.80 g Isocyanate-based curing agent 0.16 g Titanium coupling agent (Plainact 338X, manufactured by Ajinomoto Co.) 1.00 g Toluene 23.60 ml The coating composition was applied to a glass plate of 20 cm ² and dried at a temperature of 120 ° C. for 20 minutes to obtain a photocatalyst of the present invention (Sample A). The titanium oxide content of Sample A was 90% by volume based on the total amount of the titanium oxide and the hardly decomposable binder.

Example 2 The same titanium oxide as that used in Example 1 was mixed as a mixture having the following composition by shaking with a paint shaker for 3 hours to obtain a coating composition. Titanium oxide 7.64 g Fluoropolymer (Lumiflon LF200C, manufactured by Asahi Glass Co.) 2.36 g Isocyanate-based curing agent 0.47 g Titanium coupling agent (Plainact 338X, manufactured by Ajinomoto Co.) 0.76 g Toluene 22.50 ml The coating composition was applied to a glass plate of 20 cm ² and dried at a temperature of 120 ° C. for 20 minutes to obtain a photocatalyst of the present invention (Sample B). The titanium oxide content of this sample B was 70% by volume based on the total amount of the titanium oxide and the hardly decomposable binder.

Example 3 The same titanium oxide as used in Example 1 was mixed as a mixture having the following composition by shaking with a paint shaker for 1 hour and dispersed sufficiently to obtain a coating composition. Titanium oxide 9.8 g Polyorganosiloxane-based inorganic binder (3: 1 mixture of T2202A and T2202B, manufactured by Nippon Synthetic Rubber Co., Ltd.) 2.7 g Isopropyl alcohol 21.5 ml A glass plate of 20 cm ² with the coating composition having the above composition , And dried at 180 ° C. for 10 minutes to obtain a photocatalyst of the present invention (sample C). The titanium oxide content of this sample C was 90% by volume based on the total amount of the titanium oxide and the hardly decomposable binder.

Example 4 An acidic titania sol (CS-N, manufactured by Ishihara Sangyo Co., Ltd.) obtained by heating and hydrolyzing titanyl sulfate was adjusted to pH 7 by adding sodium hydroxide, followed by filtration and washing. Next, the obtained titanium oxide wet cake was heated at 110 ° C. for 3 hours.
After drying for an hour, titanium oxide was obtained. Next, the mixture was shaken with a paint shaker for 3 hours as a mixture having the following composition, mixed well, and dispersed to obtain a coating composition. Titanium oxide 7.0 g Polyorganosiloxane-based inorganic binder (3: 1 mixture of T2202A and T2202B manufactured by Nippon Synthetic Rubber Co., Ltd.) 4.3 g Isopropyl alcohol 22.5 ml A glass plate of 20 cm ² with the coating composition having the above composition , And dried at 180 ° C. for 10 minutes to obtain a photocatalyst of the present invention (Sample D). The titanium oxide content of this sample D was 80% by volume based on the total amount of the titanium oxide and the hardly decomposable binder.

Comparative Example 1 The same titanium oxide as that used in Example 1 was sufficiently mixed by shaking with a paint shaker for 1 hour as a mixture having the following composition and dispersed to obtain a coating composition. Titanium oxide 9.8 g Vinyl acetate-acryl copolymer (manufactured by Dainippon Ink and Chemicals, Inc., Boncoat 6290) 0.7 g water 24.8 ml After applying the coating composition of the above composition to a 20 cm ² glass plate, 10 After drying for a minute, a photocatalyst (sample E) was obtained. The titanium oxide content of this sample E was 90% by volume based on 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 surface of each sample was irradiated with black light so that the ultraviolet light intensity was 7 mW / cm ^2. Continued for hours. The weight loss of the binder in the photocatalyst before and after the irradiation of the black light was measured. As a result, in Samples A to D of the present invention, no weight loss was observed, and the binder was not decomposed. However, Comparative Example Sample E, which did not use the hardly decomposable binder, had a weight loss of 85%, and most of the binder was decomposed by the photocatalytic function of titanium oxide. Moreover, in Sample E, yellowing was observed, and the titanium oxide was partially peeled. FIG. 1 shows the transition of the weight loss of the binder in the photocatalyst of the samples A and C of the example and the sample E of the comparative example due to irradiation with black light. In Samples A and B of Examples 1 and 2, a coupling agent was blended. However, this coupling agent was adsorbed on the surface of the photocatalyst particles, and the coupling between the hardly decomposable binder and the photocatalyst particles was suppressed. Since the photocatalyst particles do not come into direct contact with the binder, the binder is not easily decomposed.

Next, each of the samples A to D of the present invention was separately placed in a 3 liter glass container, and acetaldehyde as a malodorous component was added to a concentration of 90 ppm to seal the glass container. Next, the surface of each sample was irradiated with a mercury lamp so that the ultraviolet light intensity became 14 mW / cm ^2, and the irradiation was continued for 60 minutes. After the irradiation, the concentration of acetaldehyde in the glass container was measured. Table 1 shows the results. In Samples A to D, acetaldehyde was efficiently decomposed by the photocatalytic function of titanium oxide.

[0023]

[Table 1]

Example 5 Acidic titania sol (CS-C, manufactured by Ishihara Sangyo Co., Ltd.) obtained by heating and hydrolyzing titanyl sulfate was adjusted to pH 7 by adding sodium hydroxide, followed by filtration, washing and drying, followed by drying. This was crushed to obtain titanium oxide. This titanium oxide 0.2
g, white cement (manufactured by Onoda Cement Co., Ltd.) 0.8
g of water and 0.7 g of water, and the whole was coated on a glass plate having an area of 50 cm ² and dried at room temperature to obtain a photocatalyst (sample F). The titanium oxide content of this sample F was 17% by volume based on the total amount of the titanium oxide and the hardly decomposable binder.

Example 6 A photocatalyst of the present invention was prepared in the same manner as in Example 5 except that 0.8 g of Denka Hi-Alumina Cement (manufactured by Denki Kagaku Kogyo Co., Ltd.) was used instead of white cement. A body (sample G) was obtained. The titanium oxide content of this sample G was 17% by volume based on the total amount of the titanium oxide and the hardly decomposable binder.

Comparative Example 2 1.0 g of the white cement used in Example 5 and 0.7 g of water
And apply the whole amount to a glass plate having an area of 50 cm ² ,
Sample H was obtained by drying at room temperature.

Comparative Example 3 Denka high alumina cement (H
i) 1.0 g and 0.7 g of water were mixed, and the area was 50 cm ^2.
The sample was obtained by applying the whole amount to the glass plate of Example 1 and drying at room temperature.

Samples F to I obtained in the above Examples and Comparative Examples
Were placed in containers each having a capacity of 4 liters, and then a standard gas of nitric oxide was injected. Next, the surface of each sample was irradiated with black light so that the ultraviolet light intensity became 1 mW / cm ^2, and the concentration of NO _x gas in each container was measured with a NO _x detector tube (11 L, manufactured by Gastec) over time. Was measured. Table 2 shows the results. Samples F and G of Examples 5 and 6 were NO
_It can be seen that, while the concentration of the _x gas is greatly reduced, the concentrations of the NO _x gas are hardly changed in the samples H and I of Comparative Examples 2 and 3. From this, it became clear that the photocatalyst of the present invention was effective for oxidizing and removing nitric oxide. When the weight loss of the cement in the samples F and G was measured by the method described above, no weight loss was recognized, and the cement was not decomposed.

[0029]

[Table 2]

Example 7 A coating composition obtained according to the method of Example 1 was applied with an area of 100 c.
The entire amount was applied to a transparent acrylic plate of m ² and dried at a temperature of 120 ° C. for 20 minutes to obtain a photocatalyst of the present invention (sample J).
The titanium oxide content of this sample J was 90% by volume based on the total amount of the titanium oxide and the hardly decomposable 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 Examples and Comparative Examples
Was attached to the inner wall of a 50-liter water tank. 45 liters of water and 20 goldfish (Japanese gold) were placed in this water tank, and two 20 W fluorescent lamps were irradiated from the outside of the water tank. At the time of breeding for 2 weeks, the attachment of algae was observed on the surface of Sample K of Comparative Example 4, whereas the attachment of algae was not observed on the surface of Sample J of Example 7. This is because even if algae adhere to the surface of the sample J of Example 7, the algae are immediately decomposed by the photocatalytic function. When the weight loss of the fluoropolymer in Sample J was measured by the above method, no weight reduction was observed, and the fluoropolymer was not decomposed.

Example 8 In Example 7, a mixture having the following composition was shaken for 1 hour with a paint shaker, mixed well, and dispersed. A coating composition obtained by spin coating (1000 rpm) was obtained.
m. × 10 seconds), except that a substrate having a first layer not containing photocatalyst particles, made of a hardly decomposable binder, was used on the transparent acrylic plate. The same treatment as in Example 7 was carried out to obtain a photocatalyst of the present invention (sample L). The content of titanium oxide as photocatalyst particles in the second layer of Sample L was 90% by volume based on the total amount of the titanium oxide and the hardly decomposable binder. Titanium oxide having no photocatalytic function (CR-90, manufactured by Ishihara Sangyo) 3.3 g Fluoropolymer (Lumiflon LF200C, manufactured by Asahi Glass Co.) 5.5 g Isocyanate-based curing agent 1.1 g Toluene 20.7 ml

When the weight loss of the binder used for the sample L was measured by the above method, no change was observed in the weight of the sample L of the present invention, the binder was not decomposed, and the titanium oxide photocatalyst particles were removed from the substrate. Did not come off. The film strength of Sample L of Example 8 was determined by pencil hardness and found to be 3H. This indicates that the titanium oxide photocatalyst particles are firmly adhered. Further, the sample L was placed in a water stream, and the ultraviolet light intensity on the surface was 2 m.
Irradiate black light so as to be W / cm ² ,
After three weeks, the titanium oxide photocatalyst particles did not peel off from the substrate.

Example 9 A photocatalyst of the present invention (sample M) was treated in the same manner as in Example 1 except that titanium oxide supporting a zinc compound was used instead of titanium oxide. I got The content of the titanium oxide photocatalyst particles supporting the zinc compound in this sample M was 90% by volume based on the total amount of the photocatalyst particles and the hardly decomposable binder. The titanium oxide supporting the 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 obtain a slurry having a pH of 10 and a conversion of TiO ₂ of 100 g / l. The slurry was subjected to a hydrothermal treatment at a temperature of 150 ° C. for 5 hours in an autoclave, then neutralized with nitric acid, filtered and washed with water. Water is added to the obtained wet cake of titanium oxide,
After preparing a slurry of 100 g / l in terms of iO ₂ , 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 aqueous solution of zinc chloride was added dropwise with stirring, followed by neutralization with 2N sodium hydroxide, followed by filtration and washing with water.
After drying at a temperature of 20 ° C. for 16 hours and pulverization, titanium oxide supporting a zinc compound was obtained. This titanium oxide has Z
The zinc compound contained an amount of nO: TiO ₂ = 1: 99 on the surface of the titanium oxide.

Example 10 A photocatalyst of the present invention (Sample N) was treated in the same manner as in Example 1 except that titanium oxide supporting an iron compound was used instead of titanium oxide. I got The content of the titanium oxide photocatalyst particles supporting the iron compound in this sample N was 90% by volume based on the total amount of the photocatalyst particles and the hardly decomposable binder. The titanium oxide supporting the iron compound was prepared as follows. 10 g of titanium oxide obtained by heating and hydrolyzing titanyl sulfate is added to TiO ₂
The slurry was adjusted to 100 g / l. 2.9 ml of a 5 g / l aqueous solution of iron chloride (FeCl ₃ .6H ₂ O) was added to the slurry, and the mixture was stirred for 1 hour. Next, the slurry was stirred for 1 hour, filtered, washed with water, and dried at 110 ° C. for 3 hours to obtain a titanium oxide supporting an iron compound. This titanium oxide has Fe / TiO ₂ = 300 pp
An amount of m of iron compound was contained on the surface of the titanium oxide.

Example 11 In Example 10, the concentration of the aqueous solution of iron chloride was changed to 50 g / l.
A photocatalyst according to the present invention (sample O) was obtained in the same manner as in Example 10, except that the above procedure was repeated. The content of the titanium oxide photocatalyst particles supporting the iron compound in the sample O was 9 parts by volume based on the total amount of the photocatalyst particles and the hardly decomposable binder.
It was 0%. This titanium oxide has Fe / TiO ₂ =
An amount of 3000 ppm of iron compound was contained on the surface of the titanium oxide.

Example 12 A photocatalyst of the present invention was treated 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 carbon as an adsorbent. (Sample P) was obtained. The total content of titanium oxide and activated carbon in Sample P was 90% by volume based on the total amount of titanium oxide, activated carbon, and the hardly decomposable binder.

Example 13 In Example 12, zeolite 0.8 was used instead of activated carbon.
Except for using g, the same treatment as in Example 12 was carried out to obtain a photocatalyst of the present invention (sample Q). The total content of titanium oxide and zeolite in Sample Q was 90% by volume based on the total amount of titanium oxide, zeolite and the hardly decomposable binder.

When the weight loss of the binder used in Samples L to Q was measured by the above method, no change in weight was observed in Samples L to Q of the present invention, the binder was not decomposed, and the titanium oxide photocatalyst was not decomposed. The particles did not peel from the substrate.

Next, Samples A, N and O of the present invention were used in 0.1%.
After each of them was separately placed in an 8-liter glass container, acetaldehyde, which is a malodorous component, was added to a concentration of about 100 ppm, and the glass container was sealed. Next, 3
After standing for 0 minutes without irradiation with ultraviolet light, each sample was irradiated with black light so that the surface of each sample had an ultraviolet light intensity of 1 mW / cm ² and continued for 60 minutes. After the irradiation, the concentration of acetaldehyde in the glass container was measured. Table 3 shows the results. In samples A, N and O, acetaldehyde was decomposed efficiently by the photocatalytic function of titanium oxide.

[0042]

[Table 3]

Next, the samples M, P, and Q of the present invention were placed in 0.
After each of them was separately placed in an 8-liter glass container, methyl mercaptan, which is a malodorous component, was added to a concentration of about 500 ppm, and the glass container was sealed. next,
After leaving for 2 hours without irradiation with ultraviolet light, the surface of each sample was irradiated with black light so that the ultraviolet light intensity was 1 mW / cm ^2, and the sample was continued for 60 minutes. After the irradiation, the concentration of methyl mercaptan in the glass container was measured. Table 4 shows the results. In Samples M, P and Q, methyl mercaptan could be efficiently removed by the photocatalytic function of titanium oxide.

[0044]

[Table 4]

In the above test, the concentration of methyl mercaptan after standing for 2 hours without irradiation with ultraviolet rays was 250 ppm, and then the concentration of methyl mercaptan after standing for 1 hour without irradiation with ultraviolet rays. Is 240 when the samples M and Q of Examples 9 and 13 are used.
ppm, which is 22 when the sample P of Example 12 is used.
It was 0 ppm.

[0046]

The photocatalyst of the present invention is obtained by adhering photocatalyst particles to a substrate via a hardly decomposable binder,
Decomposition and deterioration of the binder due to the photocatalytic function are extremely small, and the photocatalytic particles can be firmly adhered to any substrate for a long period of time without impairing the photocatalytic function. 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. Deodorant,
It is extremely useful as a sterile body. Further, the photocatalyst of the present invention can be used for a long period of time, is highly safe, has a wide range of applicable harmful substances, and furthermore, does not pollute the environment even when disposed, and is therefore extremely useful industrially. . In producing the photocatalyst of the present invention, when a fluorine-based polymer is used as the hardly decomposable binder, the adhesion of the fluorine-based polymer itself is weak, so that dirt and dirt hardly adhere to the surface of the photocatalyst. Thus, a preferable photocatalyst can be produced. In addition, the method for producing a photocatalyst of the present invention is a useful method such that any material such as plastic can be used as a base, and a photocatalyst of stable quality can be easily and easily produced. Furthermore, the coating composition of the present invention can be applied or sprayed on a substrate of any shape or a required portion of the substrate, and its photocatalytic function can be easily used. It is.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in weight of a binder in a photocatalyst due to black light irradiation of samples A and C of an example and sample E of a comparative example.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C09D 127/12 C09D 183/04 183/04 B01J 23/74 301A (72) Inventor Hajime Murakami 2-chome Nishi-Shibukawa, Kusatsu-shi, Shiga Prefecture No. 1 Ishihara Sangyo Co., Ltd. Central Research Laboratory (72) Inventor Yasuo Fukui 2-3-1 Nishi-Shibukawa, Kusatsu-shi, Shiga Prefecture Ishihara Sangyo Co., Ltd. Central Research Laboratory (72) Inventor Mitsuru Watanabe Nishi-Shibukawa, Kusatsu-shi, Shiga Prefecture Chome 3-1, Ishihara Sangyo Co., Ltd. (72) Inventor Akira Fujishima 710-5 Nakamaruko, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Building No. 506

Claims (8)

[Claims] 1. A coating composition for producing a photocatalytic function by dispersing photocatalyst particles and a hardly decomposable binder in a solvent, wherein the hardly decomposable binder is a fluorine-based polymer or a silicon-based polymer. And a coating composition, which is at least one selected from silicon compounds. 2. The coating composition according to claim 1, further comprising a coupling agent. 3. The coating composition according to claim 1, further comprising a crosslinking agent. 4. The coating composition according to claim 1, wherein the amount of the photocatalyst particles is 5 to 98% by volume based on the total amount of the photocatalyst particles and the hardly decomposable binder. 5. The coating composition according to claim 1, wherein the hardly decomposable binder is a silicon compound. 6. The coating composition according to claim 5, wherein the silicon compound is at least one silicon compound selected from water glass, colloidal silica, and polyorganosiloxane. 7. The coating composition according to claim 1, wherein the hardly decomposable binder is a fluoropolymer. 8. The coating composition according to claim 7, wherein the fluoropolymer is a fluoropolymer having a copolymer of vinyl ether and / or vinyl ester and fluoroolefin as a main component.