JP2013220397A - Metal compound for photocatalyst, photocatalytic composition, photocatalytic coating film and photocatalytic coating product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalytic metal compound which exerts necessary photocatalytic activity without damaging a primer coating film.SOLUTION: A photocatalytic metal compound is used for a photocatalyst in which the value of [HO] generated when ultraviolet rays having a wavelength of 365 nm and a strength of 5 mW/cmare radiated to a predetermined suspension containing the metal compound for 60 seconds is not more than 80 μM, and the number of holes defined by low temperature ESR measurement is 1.5×10or more.

Description

  The present invention relates to a metal compound for photocatalyst, a photocatalyst composition, a photocatalyst coating film, and a photocatalyst coating product.

In recent years, in order to impart antifouling performance to architectural outer walls such as houses and buildings, a photocatalytic coating has been put into practical use, and the photocatalytic coating is applied to the architectural outer wall to form a photocatalytic coating film. This photocatalyst coating material is mixed with a metal compound material having photocatalytic activity so as to exhibit photocatalytic activity. The most commonly used of these compounds is titanium dioxide (TiO ₂ ). When light (UV) strikes the titanium dioxide to generate excited electrons and holes by the generated excited electrons and holes, in the presence of oxygen and water at the catalyst surface, · O ₂ ^- and · OH (“·” Indicates an unpaired electron, meaning that the chemical species to which it is attached is a radical species). Holes and generated active oxygen species exhibit important photocatalytic activities such as a soil decomposition function and a nitrogen oxide removal function. However, the active oxygen species also damages the coating film (hereinafter referred to as “undercoat film”) of the base material to which the photocatalytic coating is applied. Therefore, a two-layer coat type photocatalyst coating in which a protective layer typified by a silicone resin is provided between the base coating and the photocatalytic coating has been proposed (see Patent Document 1).

JP 2003-73610 A

  Since a film such as a silicone resin used as a protective layer of a two-layer coat type photocatalyst paint is hard and brittle, it is impossible to completely prevent the occurrence of minute through cracks in the film. As a result, it was not possible to prevent the aforementioned active oxygen species from damaging the base coating film through the through cracks. Also, the two-layer coat type photocatalyst paint has difficulty in on-site workability. In order to improve these problems, a one-layer coat type photocatalyst paint that can prevent damage to the base coating film and does not require a protective layer is desired.

The present invention realizes such a one-layer coat type photocatalyst coating material as described above, and does not damage the base coating film, and exhibits a necessary photocatalytic activity, and a photocatalyst composition containing the metal compound. An object is to provide a product, a photocatalyst coating film, and a photocatalyst coating product.

  As a result of intensive studies aimed at solving the above problems, the present inventors have reached the present invention.

That is, the present invention is as follows.
[1] A metal compound used as a photocatalyst, which is generated when a predetermined suspension containing the metal compound is irradiated with ultraviolet light having a wavelength of 365 nm and an intensity of 5 mW / cm ² for 60 seconds [H ₂ O ₂ ] A metal compound for photocatalyst having a value of 80 μM or less and a hole amount defined by low temperature ESR measurement of 1.5 × 10 ¹³ or more.
[2] A metal compound used as a photocatalyst, and a value of [.OH] generated when a predetermined suspension containing the metal compound is irradiated with ultraviolet light having a wavelength of 365 nm and an intensity of 5 mW / cm ² for 60 seconds. A metal compound for photocatalyst that is 0.2 μM or less and has an amount of holes defined by low-temperature ESR measurement of 1.5 × 10 ¹³ or more.
[3] The metal compound for photocatalysts according to [1] or [2], which is a metal oxide having a modified particle surface.
[4] The metal compound for photocatalysts according to [1] or [2], which is a metal oxide whose particle surface is modified with silica.
[5] A photocatalytic composition comprising the photocatalyst metal compound according to any one of [1] to [4] and a resin.
[6] The photocatalyst composition according to [5], wherein the resin includes polymer particles and particles of a metal oxide other than the metal compound for photocatalyst.
[7] A photocatalyst coating film formed from the photocatalyst composition of [5] or [6].
[8] A photocatalyst-coated product comprising the photocatalyst coating film of [7].

If the metal compound for photocatalysts of the present invention is used, a photocatalyst layer that exhibits the necessary photocatalytic activity can be provided on the base coating film without damaging the base coating film, and excellent on-site workability. A single-layer coating type photocatalytic coating can be provided.

Example of ESR spectrum of metal compound for photocatalyst (under dark and under UV irradiation) Weak pitch ESR spectrum (under UV irradiation)

Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail.

The metal compound for photocatalyst of this embodiment is a metal compound used as a photocatalyst, and ultraviolet light (hereinafter referred to as “specific ultraviolet light”) having a wavelength of 365 nm and an intensity of 5 mW / cm ² is applied to a predetermined suspension containing the metal compound. The value of [H ₂ O ₂ ] generated upon irradiation for 60 seconds is 80 μM or less.
In the present specification, the “predetermined suspension” means that 3.5 mL of 0.01 M NaOH aqueous solution is injected into a quartz cell (optical path (length) 1 cm × width 1 cm), and further 15 mg of a metal compound is added thereto. Is a suspension obtained by adding and stirring the powder.

Of the amount of active oxygen species generated when irradiated with specific ultraviolet light, the value of [H ₂ O ₂ ], that is, oxidol (hydrogen peroxide) must be 80 μM or less so as not to damage the underlying coating film. It is preferably 20 μM or less, and more preferably 10 μM or less. Here, the ultraviolet light means a wavelength region of 400 nm or less. Further, μM represents a micromolar, and 1 μM = 10 ⁻⁶ M = 10 ⁻⁶ mol / L.

Of the active oxygen species, H ₂ O ₂ is a stable substance compared to radical species such as .OH, and has a long life compared to the lifetime of radical species (less than 1 second), and moves to a long distance. This will damage the undercoat. Therefore, [H ₂ O ₂ ] is preferably small. That is, that the value of [H ₂ O ₂ ] is 80 μM or less means that the amount of H ₂ O ₂ generated is small and the metal compound for photocatalyst does not hurt the base coating film. On the other hand, a metal compound for photocatalyst having a value of [H ₂ O ₂ ] larger than 80 μM generates a large amount of H ₂ O _{2 and} damages the underlying coating film.

The metal compound for photocatalyst of this embodiment is a metal compound used as a photocatalyst, and the amount of holes defined by low temperature ESR (Electron spin resonance electron spin resonance) measurement is 1.5 × 10 ¹³ or more. When used as a photocatalytic coating, it is mainly direct oxidation by holes that exhibits the necessary decomposition activity. In order to express the necessary decomposition activity, the hole amount is 1.5 × 10 ¹³ or more, and more preferably 4.5 × 10 ¹³ or more.

The metal compound for photocatalyst of the present embodiment has [· OH], that is, the value of hydroxyl radical, among the above active oxygen species generated when irradiated with specific ultraviolet light for 60 seconds so as not to damage the underlying coating film. It is preferably less than 0.2 μM, more preferably less than 0.1 μM, and even more preferably less than 0.05 μM. Here, the ultraviolet light means a wavelength region of 400 nm or less. Further, μM represents a micromolar, and 1 μM = 10 ⁻⁶ M = 10 ⁻⁶ mol / L.

  Of the active oxygen species, .OH is a radical species that acts to damage the coating film. That is, a value of [.OH] of less than 0.2 μM means that the amount of .OH generated is small and the base coating film is a metal compound for photocatalysis that does not hurt. On the other hand, a metal compound for photocatalyst having a value of [.OH] of more than 0.2 μM generates a large amount of .OH and damages the undercoat.

  The metal compound for photocatalyst of the present embodiment may satisfy at least one of the above-mentioned two types of active oxygen species satisfies the above-mentioned condition of the amount of active oxygen species from the viewpoint of more effectively and surely achieving the effect of the present invention. Preferably, it is more preferable that all of the two types satisfy the above-mentioned conditions for the amount of active oxygen species.

  As a method of adjusting the amount of each active oxygen species within the above range, for example, a metal, metal complex or metal oxide, which will be described later, is modified on the particle surface to reduce the amount of active oxygen species. A method is mentioned. Although the mechanism is not completely elucidated, it is considered that the active species are inactivated or trapped by the surface-modified substance. However, the method for adjusting the amount of each active oxygen species is not limited to these.

H ₂ O ₂ can be quantified using the lucigenin chemiluminescence method. In a quartz cell (optical path (length) 1 cm x width 1 cm) placed on a magnetic stirrer in a dark box, 3.5 mL of 0.01 M NaOH aqueous solution is added to adjust pH 9 and further 15 mg of metal compound (photocatalyst) A powder (for example, obtained by drying a sol, the same applies hereinafter) is added and suspended to obtain a suspension. Next, using the LED (Hamamatsu Photonics), model number “LC-L2”, wavelength: 365 nm, intensity 5 mW / cm ² ) as a light source, the cell containing the suspension was irradiated with ultraviolet light for 60 seconds. Do. After irradiation, 50 μL of a 0.7 mM lucigenin solution is added, and chemiluminescence generated by H ₂ O ₂ is passed through a bandpass filter, and then detected with an electron-cooled photomultiplier tube.

-The quantitative method of OH can be performed using the coumarin fluorescent probe method. First, a 0.1 mM aqueous solution of coumarin is prepared, and a suspension is obtained by suspending 15 mg of a metal compound (photocatalyst) powder such as TiO ₂ and 35 mL of an aqueous solution of coumarin in a quartz cell having the same dimensions as described above. This suspension is irradiated with LED light having a wavelength of 365 nm and an intensity of 5 mW / cm ² for 60 seconds. Next, in order to separate a metal compound (photocatalyst) powder such as TiO ₂ from the suspension, 0.5 g of KCl is added to the suspension after the irradiation and left in a dark place for 24 hours. Thereafter, the supernatant is taken as a sample, and fluorescence is measured with a Fluorescence spectrophotometer (850 type, manufactured by HITACHI) (at this time, it has been confirmed that light scattering during the fluorescence measurement due to the addition of KCl has no effect). OH is quantified by comparing the fluorescence intensity of a known concentration of coumarin with the fluorescence intensity of the sample.

The low temperature ESR was measured using ESP-30E manufactured by BRUCKER in a vacuum (0.1 Torr), 77K, a sample amount of 20 mg, under darkness and under ultraviolet irradiation. The hole integral value was calculated from the difference spectrum by subtracting the dark ESR spectrum from the ESR spectrum under ultraviolet irradiation. The number of holes was calculated by comparing with the integrated value of Weak pitch (10 ¹³ pieces).

The metal compound for photocatalyst of this embodiment is a metal compound used as a photocatalyst, and is preferably a metal compound obtained by modifying the particle surface. If the modification treatment is not performed, the amount of active oxygen species such as H ₂ O ₂ and .OH increases, and the base coating film is damaged. Examples of the substance to be modified include silica, aluminum, copper oxide, and iron oxide. Among these, silica is particularly preferable. The same effect can be obtained by modification with a metal such as Fe, Cu, Al, Pt or a complex such as chloroplatinic acid.

  As a method for modifying silica, a silicon compound is added to a slurry of titanium oxide, and a hydrous oxide is precipitated by neutralization or the like. As the silicon compound, a water-soluble alkali metal silicate such as sodium silicate can be used. Among them, sodium silicate is preferable because it is colorless and the titanium oxide sol is not colored. The treatment amount of the hydrous oxide of silicon is preferably 3 to 25% by mass, more preferably 5 to 20% by mass based on the oxide based on titanium oxide. When the treatment amount is less than the above range, the amount of active oxygen species is increased, and the base coating film is damaged, which is not preferable. On the other hand, when the treatment amount is larger than the above range, titanium oxide is aggregated conversely, the viscosity of the sol tends to increase, the dispersibility is deteriorated, and it is difficult to obtain a product having excellent transparency, which is not preferable.

Examples of the photocatalytic metal compound include TiO ₂ , ZnO, SrTiO ₃ , CdS, GaP, InP, GaAs, BaTiO ₃ , BaTiO ₄ , BaTi ₄ O ₉ , K ₂ NbO ₃ , Nb ₂ O ₅ , Fe ₂ O _{3. , Ta 2 O 5, K 3} Ta 3 Si 2 O 3, WO 3, SnO 2, Bi 2 O 3, BiVO 4, NiO, Cu 2 O, SiC, MoS 2, InPb, RuO 2, and CeO ₂ can be mentioned It is done. Among these, metal oxides are preferable from the viewpoint of better photocatalytic activity.

  As a metal compound for photocatalysts of this embodiment, titanium oxide is preferable from the viewpoint of safety and cost. Titanium oxide has anatase, rutile and brookite crystal structures, any of which can be used.

  The metal compound for photocatalyst according to the present embodiment may have an average (arithmetic average) primary particle diameter in the range of 1 to 400 nm from the viewpoint of improving the performance as a photocatalyst and exhibiting good dispersibility. Preferably, it is in the range of 1 to 100 nm, more preferably in the range of 5 to 50 nm. In addition, when the particle shape of the metal compound for photocatalysts has a major axis and a minor axis such as a rod shape, the arithmetic average of the major axis and minor axis is preferably within the above range. The primary particle diameter of the metal compound for photocatalyst is derived as an arithmetic average of 50 arbitrarily selected particles measured by electron microscope observation.

 As the resin that can be used in the photocatalyst composition of the present invention, all synthetic resins and natural resins can be used. Further, the form may be a pellet or a form dissolved or dispersed in a solvent, and there is no particular limitation, but the form of a resin paint for coating is most preferable.

  The resin according to this embodiment is not particularly limited, and all synthetic resins and natural resins can be used. Further, the form may be a pellet or a form dissolved or dispersed in a solvent, and there is no particular limitation, but the form of a resin paint for coating is most preferable. Examples of resin paints include oil-based paints, lacquers, solvent-based synthetic resin paints (acrylic resins, epoxy resins, urethane resins, fluororesins, silicone-acrylic resins, alkyd resins, aminoalkyd resins, vinyl. Resin-based, unsaturated polyester resin-based, chlorinated rubber-based, etc.), water-based synthetic resin coatings (emulsion-based, water-based resin-based, etc.), solvent-free synthetic resin coatings (powder coatings, etc.), inorganic coatings, electrical insulation coatings, etc. be able to.

  Among these resin coatings, silicone resins and fluorine resins that are hardly decomposable with respect to the photocatalyst, and a combination resin coating of a silicone resin and a fluorine resin are preferably used.

  Examples of such silicone resins include alkoxysilanes and / or organoalkoxysilanes, their hydrolysis products (polysiloxanes) and / or colloidal silica, and acrylic-silicone resins having a silicone content of 1 to 80% by mass. , An epoxy-silicone resin, a urethane-silicone resin, an alkoxysilane and / or an organoalkoxysilane, a hydrolysis product thereof (polysiloxane) and / or a resin containing 1 to 80% by mass of colloidal silica. These silicone resins may be any of a solvent-soluble type, a dispersion type, and a powder type, and may contain additives such as a crosslinking agent and a catalyst.

  Examples of the metal oxide particles other than the metal compound for photocatalyst according to the present embodiment include silicon dioxide (silica) particles, aluminum oxide (alumina) particles, calcium silicate particles, magnesium oxide particles, antimony oxide particles, and zirconium oxide particles. And composite oxide particles thereof. These are used singly or in combination of two or more. Among them, from the viewpoint of increasing the surface hydroxyl groups, increasing the surface area of the metal oxide particles, and strengthening the bond between the metal oxide particles or the bond between the metal oxide and the polymer particles, the silicon dioxide particles, Aluminum oxide particles, antimony oxide particles and composite oxide particles thereof are preferable, and colloidal silica particles which are a dispersion in a solvent of silica having silicon dioxide as a basic unit are more preferable.

  Colloidal silica can be prepared and used by a sol-gel method, and a commercially available product can also be used. For preparation by the sol-gel method, Werner Stober et al; Colloid and Interface Sci. , 26, 62-69 (1968), Rickey D .; Badley et al; Lang muir 6, 792-801 (1990), Color Material Association Journal, 61 [9] 488-493 (1988), and the like. Examples of the acidic colloidal silica using water as a dispersion medium include, as commercial products, Snowtex (trademark) -O manufactured by Nissan Chemical Industries, Ltd., Snowtex-OS, Adelite (trademark) AT manufactured by Asahi Denka Kogyo Co., Ltd. -20Q, Clariant Japan Co., Ltd. clebosol (trademark) 20H12, clebosol 30CAL25, etc. can be used.

  Examples of basic colloidal silica include silica stabilized by addition of alkali metal ions, ammonium ions, and amines, such as SNOWTEX-20, SNOWTEX-30, SNOWTEX-C, manufactured by Nissan Chemical Industries, Ltd. SNOWTEX-C30, SNOWTEX-CM40, SNOWTEX-N, SNOWTEX-N30, SNOWTEX-K, SNOWTEX-XL, SNOWTEX-YL, SNOWTEX-ZL, SNOWTEX PS-M, SNOWTEX PS- L, etc .; Adelite AT-20, Adelite AT-30, Adelite AT-20N, Adelite AT-30N, Adelite AT-20A, Adelite AT-30A, Adelite AT-40, Adelite AT-50, etc. manufactured by Asahi Denka Kogyo Co., Ltd. ; Clariant Japan Co., Ltd. Ltd. Kurebozoru 30R9, Kurebozoru 30R50, such Kurebozoru 50R50, DuPont Ludox (TM) HS-40, Ludox HS-30, Ludox LS, mention may be made of Ludox SM-30.

  Further, as colloidal silica using a water-soluble solvent as a dispersion medium, for example, MA-ST-M (methanol dispersion type having a particle diameter of 20 to 25 nm), IPA-ST (particle diameter of 10) manufactured by Nissan Chemical Industries, Ltd. ˜15 nm isopropyl alcohol dispersion type), EG-ST (ethylene glycol dispersion type with particle diameter of 10 to 15 nm), EG-ST-ZL (ethylene glycol dispersion type with particle diameter of 70 to 100 nm), NPC-ST (particles) And ethylene glycol monopropyl ether dispersion type) having a diameter of 10 to 15 nm.

  These colloidal silicas may be used alone or in combination of two or more. Colloidal silica may contain alumina, sodium aluminate or the like as a minor component. Colloidal silica may contain an inorganic base (such as sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia) or an organic base (such as tetramethylammonium) as a stabilizer. The average particle diameter of the metal oxide particles is preferably 100 nm or less. More preferably, it is 50 nm or less, More preferably, it is 20 nm. When metal oxide particles having an average particle size of 10 nm or less are used, the resulting photocatalyst coating film has very high transparency and is most preferable. The particle diameter (number average particle diameter) of the metal oxide particles is measured according to the method described in the following examples.

  Although the film thickness of the photocatalyst coating film of this embodiment is not specifically limited, It is preferable that it is 0.05-100 micrometers, It is more preferable that it is 0.1-10 micrometers, It is 1.0-2.5 micrometers. Further preferred. When the thickness is 100 μm or less, good transparency can be secured, and when the thickness is 0.05 μm or more, functions such as antifouling properties and photocatalytic activity can be more effectively expressed.

  The photocatalyst coating film of the present embodiment may contain a dispersion stabilizer from the viewpoint of dispersion stability of each particle contained therein. Examples of the dispersion stabilizer include various water-soluble oligomers selected from the group consisting of polycarboxylic acids and sulfonates, polyvinyl alcohol, hydroxyethyl cellulose, starch, maleated polybutadiene, maleated alkyd resin, polyacrylic acid (salt ), Various synthetic or natural polymer materials represented by polyacrylamide and acrylic resins. A dispersion stabilizer is used individually by 1 type or in mixture of 2 or more types.

  In addition, the photocatalyst coating film of the present embodiment has components added to and blended with ordinary paints and molding resins, for example, a solvent, a thickener, a leveling agent, and a thixotropic agent, depending on the application and method of use. , Antifoaming agent, Freezing stabilizer, Matting agent, Crosslinking reaction catalyst, Pigment, Curing catalyst, Crosslinking agent, Filler, Anti-skinning agent, Dispersant, Wetting agent, Light stabilizer, Antioxidant, UV absorber , Rheology control agent, antifoaming agent, film forming aid, rust preventive agent, dye, plasticizer, lubricant, reducing agent, preservative, antifungal agent, deodorant, anti-yellowing agent, antistatic agent or A charge adjusting agent or the like may be contained.

  The photocatalyst coating film of this embodiment is obtained by applying the photocatalyst composition to the surface of a substrate or a coating covering the substrate and drying it. Examples of the base material on which the photocatalyst composition is applied include organic substrates represented by synthetic resins, natural resins, fibers, inorganic substrates represented by metals, ceramics, glass, stone, cement, concrete, and combinations thereof. Is mentioned.

Examples of the synthetic resin include thermoplastic resins and curable resins (thermosetting resins, photocurable resins, moisture curable resins, and the like). Specific examples include silicone resin, acrylic resin, methacrylic resin, fluorine resin, alkyd resin, aminoalkyd resin, vinyl resin, polyester resin, styrene-butadiene resin, polyolefin resin, polystyrene resin, polyketone resin, polyamide resin, polycarbonate. Resin, polyacetal resin, polyether ether ketone resin, polyphenylene oxide resin, polysulfone resin, polyphenylene sulfone resin polyether resin, polyvinyl chloride resin, polyvinylidene chloride resin, urea resin, phenol resin, melamine resin, epoxy resin, urethane resin, A silicone-acrylic resin is mentioned. Examples of the natural resin include cellulose resins, isoprene resins typified by natural rubber, and protein resins typified by casein.

  When the substrate is a resin plate or fiber, the surface thereof may be subjected to a surface treatment such as a corona discharge treatment, a flame treatment, or a plasma treatment, but these surface treatments are not essential.

  The photocatalyst coating film of the present embodiment can be applied by any method according to the use of the photocatalyst composition. Examples of the application method include spray spraying, flow coating, roll coating, brush coating, dip coating, spin coating, screen printing, casting, gravure printing, and flexographic printing.

  The photocatalyst coating film of this embodiment is obtained by applying a photocatalyst composition and then drying to remove volatile components. At this time, for example, after drying at a low temperature of 20 ° C. to 80 ° C., heat treatment at 20 ° C. to 500 ° C., more preferably 40 ° C. to 250 ° C. may be performed as desired, and ultraviolet irradiation or the like is performed. Also good.

  The photocatalyst product of the present embodiment includes a substrate and the photocatalyst coating film formed on the substrate. The photocatalyst-coated product may be the same as the known embodiment except that the photocatalyst coating film of the present embodiment is provided. Specific examples of the photocatalyst-coated product of the present embodiment include, for example, building materials, building exteriors, building interiors, window frames, window glass, structural members, building facilities such as houses, vehicle illumination lamp covers, window glass, mechanical devices, Exterior of goods, dustproof cover and painting, display equipment, its covers, traffic signs, various display devices, display objects such as advertising towers, sound insulation walls for roads and railways, bridges, exterior and painting of guardrails, tunnel interior and painting , Electronic parts used outside such as insulators, solar battery covers, solar water heater heat collection covers, etc., and exterior parts of electrical equipment, especially exteriors such as transparent members, greenhouses and greenhouses. This photocatalyst-coated product may be obtained by applying a photocatalyst composition on the surface of a substrate and drying it to form a photocatalyst coating film on the substrate, but the production method is not limited thereto. For example, the substrate and the photocatalyst coating film may be molded at the same time, and more specifically, may be integrally molded.

  In addition, after the photocatalyst coating film of the present embodiment is formed on a substrate, the photocatalyst coating film is adhered to another substrate by adhesion, fusion, or the like in a state where the photocatalyst coating film is peeled off or adhered to the substrate. You may let them.

  In the present embodiment, a chemiluminescence method and a low temperature ESR are combined as a method for selecting a metal compound for photocatalyst that exhibits the necessary photocatalytic activity without damaging the underlying coating film. The chemiluminescence method quantifies reactive oxygen species that move to a long distance and damage the underlying coating film by the generated chemiluminescence, such as the aforementioned lucigenin chemiluminescence method and coumarin fluorescent probe method. As described above, the low temperature ESR is a method capable of quantifying holes that exhibit a decomposition activity necessary as a photocatalytic coating. The damage to the undercoat and the activity as a photocatalyst coating required that the photocatalyst composition be applied to evaluate the coat. However, according to this method, which combines chemiluminescence method and low temperature ESR, there is no need for troublesome paint preparation, coating film preparation, and long-term weather resistance test. A metal compound for photocatalyst that exhibits photocatalytic activity can be easily selected.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to the said this embodiment. The present invention can be variously modified without departing from the gist thereof.

  The following examples, reference examples and comparative examples will specifically explain the present invention, but these do not limit the scope of the present invention. Various physical properties were measured by the following methods.

1. Quantitative determination of H ₂ O ₂ The suspension obtained in the same manner as in 1 above was irradiated with ultraviolet light in the same manner as above, and after waiting for disappearance of O ₂ ⁻ for 30 minutes, a 7 mM luminol solution was then added. Was added to the suspension. Ten minutes later, 50 μL of a 6.2 μM hemoglobin solution was added to the suspension, and the resulting chemiluminescence was detected to derive the value of [H ₂ O ₂ ].

2. -Determination of OH A 0.1 mM coumarin aqueous solution was prepared, and 15 mg of a metal compound (photocatalyst) powder and 35 mL of a coumarin aqueous solution were suspended in a quartz cell having the same dimensions as described above to obtain a suspension. This suspension was irradiated with LED light having a wavelength of 365 nm and an intensity of 32 mW / cm ² for 120 seconds. Next, in order to separate the metal compound (photocatalyst) powder from the suspension, 0.5 g of KCl was added to the suspension after the irradiation, and the mixture was allowed to stand in the dark for 24 hours. Thereafter, the supernatant was taken as a sample, and fluorescence was measured with a Fluorescence spectrophotometer (model number “RF-5300PC”, manufactured by SHIMADZU). At this time, light scattering at the time of fluorescence measurement by addition of KCl did not affect. By comparing the fluorescence intensity of a coumarin having a known concentration with the fluorescence intensity of the sample, .OH was quantified to derive a value of [.OH].

3. Hole quantification
Using ESP-30E manufactured by BRUCKER, vacuum (0.1 Torr), 77K, sample amount 20 mg, darkness and ultraviolet irradiation were performed. The hole integral value was calculated from the difference spectrum by subtracting the dark ESR spectrum from the ESR spectrum under ultraviolet irradiation. The number of holes was calculated by comparing with the integrated value of Weak pitch (10 ¹³ pieces).

4). Quantification of surface modification products Quantification was performed by the FP method, which uses a fluorescent X-ray analyzer to perform quantitative analysis using the theory and fundamental parameters (FP).

5. Number average particle diameter A sample was appropriately diluted by adding a solvent so that the solid content in the sample was 1 to 20% by mass, and measured using a wet particle size analyzer (Microtrac UPA-9230, manufactured by Nihon Koki Co., Ltd.).

6). Film thickness The film thickness was measured using a film thickness measuring device (SPECTRA COOP, trade name “HandyLambda II THICKNESS”) equipped with a halogen light source device (MORITEX, trade name “MHF-D100LR”). And measured.

7. Appearance (color difference)
The color difference from the standard plate was determined using a color guide (BYK Gardner).

8). Weather resistance (color difference after exposure to SWOM5000 hours)
Using the sunshine weather meter manufactured by Suga Test Instruments Co., Ltd., an exposure test (black panel temperature 63 ° C., rainfall 18 minutes / 2 hours) is performed, and the color difference between the exposure before and 5000 hours after the start of the exposure is calculated as described in 7 above. The color difference before exposure was used as a standard, and the state change before and after exposure was evaluated as ΔE.
○: ΔE * is less than 3 ×: ΔE * is 3 or more.

9. Observation of underlying coating film deterioration After embedding the sample in an epoxy resin (trade name, Quetol 812), an ultrathin section having a thickness of 50 to 60 nm was prepared and supported by a ULTRACUT-N microtome (trade name) manufactured by Reichert, Germany. After loading on a mesh with a film attached, carbon deposition is carried out to make a sample for microscopy, and the cross-section of the coating film is observed with a TEM (HITACHI HF2000 type, acceleration voltage: 125 kV) to evaluate the deterioration state of the underlying coating film. did.
○: Deterioration of the base coating film is not observed.
◯: Deterioration of the base coating film is observed slightly, but it is judged that there is no problem as a whole.
Δ: Some deterioration of the base coating film is observed.
X: Deterioration of the base coating film is observed as a whole.

10. Photocatalytic activity (pigment degradation activity)
Calculated according to JIS R1703-2. Specimen purification conditions were irradiation for 24 hours at an illuminance of 1 mW / cm2, methylene blue adsorption conditions were for an adsorption liquid concentration of 0.02 mM and an adsorption time of 24 hours. The absorption spectrum of the test solution collected after irradiation was measured with a spectrophotometer. The absorbance measurement wavelength is 664 nm.
A: Decomposition activity index is 10 nM / min or more.
○: Degradation activity index is 5 nM / min or more and less than 10 nM / min.
X: Degradation activity index is less than 5 nM / min.

[Reference Example 1] Silica-modified rutile-type titanium oxide 700 mL of a titanium tetrachloride aqueous solution having a concentration of 200 g / L as TiO ₂ and a sodium hydroxide aqueous solution having a concentration of 100 g / L as Na ₂ O, and the pH of the system being 5 to 5 9 was added in parallel to maintain water. Then, after adjusting the pH of the system to 7, it is filtered, washed until the conductivity of the filtrate becomes 100 μS / cm, and the solid content concentration is 28. 3% by mass of titanium oxide wet cake 1 was obtained. The titanium oxide fine particles had a rutile structure, and the average particle size was 8 nm.

  The obtained rutile-type titanium oxide wet cake 1 was diluted with pure water to prepare a 1 mol / L slurry. 1 L of this slurry is charged into a 3 L flask, and 1 L of 1N nitric acid is added so that the molar ratio of titanium oxide / nitric acid is 1 / L, heated to a temperature of 95 ° C., and maintained at this temperature for 2 hours. Then, acid heat treatment was performed. Next, the acid-heated slurry is cooled to room temperature, neutralized with 28% aqueous ammonia (pH = 6.7), filtered, and washed until the filtrate has a conductivity of 100 μS / cm. Thus, a titanium oxide wet cake 2 having a solid content concentration of 25% by mass was obtained.

A 10% strength aqueous sodium hydroxide solution was added to the obtained titanium oxide wet cake 2, repulped, and then dispersed for 3 hours with an ultrasonic cleaner, pH = 10.5, solid content concentration 10 mass. % Alkaline titanium oxide sol was obtained. This alkaline titanium oxide sol 2L was charged into a 3 L flask, heated to a temperature of 70 ° C., and an aqueous sodium silicate solution having a concentration of 432 g / L as SiO ₂ 6 9. After adding 4 ml and then raising the temperature to 90 ° C. and aging for 1 hour, 10% sulfuric acid was added to adjust the pH to 6, and the surface of titanium oxide was surface-treated with a hydrous oxide of silicon.

4. the obtained titanium oxide sol is cooled to room temperature; 4 L of pure water was added, impurities were removed and concentrated using a desalting and concentrating device, and pH = 7. 3, solid content concentration 29 mass%, conductivity 1. A neutral rutile-type titanium oxide sol of 18 mS / cm was obtained. It contained 15 wt% of silicon oxide hydroxide with SiO ₂ basis relative to TiO _2. The average particle diameter of titanium oxide in this sol was 9 nm.

[Reference Example 2] Platinum-modified titanium oxide Pure water 0. To 5 liters, hexachlorochloroplatinic acid hexahydrate 0. 6 75 g (corresponding to 0.5% by mass as Pt with respect to TiO 2) was added and stirred, the average major axis diameter 64 nm, the average minor axis diameter 13 nm (axial ratio 4.9), the specific surface area 160 m ² / After adding 50 g of spindle-shaped titanium oxide fine particles having an anisotropic shape of g, 1.44 ml of a hypophosphorous acid aqueous solution (50% aqueous solution) was added, and heat treatment was performed at 90 ° C. for 1 hour. It was. After the heat treatment, it was cooled, filtered, washed, dried at 110 ° C. for one day and night, and then pulverized with a Reika machine to obtain platinum-modified titanium oxide.

[Reference Example 3] Silica-modified anatase-type titanium oxide Titanium ore was reacted with sulfuric acid, and the resulting titanium sulfate solution was hydrolyzed with heating to form agglomerated metatitanic acid as an aqueous slurry of 30% by mass in terms of TiO _2. The slurry was neutralized with aqueous ammonia to pH 7 and then filtered and washed to remove sulfate radicals. Nitric acid was added to the obtained dehydrated cake and peptization treatment was carried out to adjust the pH of titanium oxide fine particles (primary particle diameter 7 nm) containing anatase type crystal structure. 5 acidic titanium oxide sol was obtained. The obtained acidic titanium oxide sol was diluted with pure water to make 600 g of titanium oxide sol 200 g / L in terms of TiO ₂ , then heated to 70 ° C., and then a sodium silicate aqueous solution having a SiO ₂ equivalent concentration of 432 g / L. 2 0. 8 ml was added simultaneously with 20% sulfuric acid and then aged for 30 minutes. Next, the pH was adjusted to 8 with a 10% aqueous sodium hydroxide solution, the pH was adjusted to 6 with a 2% aqueous sulfuric acid solution, filtered and washed to obtain a wet cake. This wet cake was repulped into pure water and then ultrasonically dispersed to obtain a titanium oxide sol (solid content concentration 20% by mass, pH = 7.5) stable in the neutral range. In this sample, the aggregated silica was deposited in a porous state on the surface of the titanium oxide fine particles, and the content thereof was 7 parts by mass in terms of SiO _{2 with} respect to 100 parts by mass of TiO ₂ .

Reference Example 4 Synthesis of Polymer Emulsion Particles (B1) Aqueous Dispersion A reactor having a reflux condenser, a dropping tank, a thermometer, and a stirrer was charged with 400 g of ion-exchanged water and a 10% by mass dodecylbenzenesulfonic acid aqueous solution 4 After charging 0.0 g, the temperature in the reactor was heated to 80 ° C. with stirring. In this reactor, 54.5 g of dimethyldimethoxysilane, 34.4 g of phenyltrimethoxysilane, and 1.0 g of methyltrimethoxysilane, and 15.0 g of a 2% by weight aqueous solution of ammonium persulfate were added to the reactor. It was dripped simultaneously over about 2 hours in the state which maintained the inside temperature at 80 degreeC. Thereafter, the temperature in the reactor was maintained at 80 ° C., and stirring was continued for about 1 hour. Next, a mixed liquid composed of 12.3 g of n-butyl acrylate, 13.5 g of phenyltrimethoxysilane, 31.4 g of tetraethoxysilane, and 1.2 g of 3-methacryloxypropyltrimethoxysilane, and methyl methacrylate 24. 6 g, acrylic acid 1 g, reactive emulsifier (trade name “Adekaria Soap SR-1025”, manufactured by Asahi Denka Co., Ltd., 25% solids aqueous solution), reactive emulsifier (trade name “AQUALON KH-1025”) , Daiichi Kogyo Seiyaku Co., Ltd., 25% solid content aqueous solution) 0.7 g, ammonium persulfate 2% by weight aqueous solution 8.5 g, and a mixture of ion-exchanged water 255 g. It was dripped simultaneously over about 2 hours in the state kept at ° C. Further, the temperature in the reactor was maintained at 80 ° C. and stirring was continued for about 2 hours, and then the mixture was cooled to room temperature and filtered through a 100-mesh wire mesh. The solid content was adjusted to 10.0% by mass with ion-exchanged water to obtain an aqueous dispersion of polymer emulsion particles (B1) having a number average particle size of 120 nm as polymer particles.

[Example 1]
Table 1 shows [H2O2], [.OH], and the amount of holes of the silica-modified titanium oxide prepared in Reference Example 1. 34.5 g of this titanium oxide as a metal oxide for photocatalyst (15% by mass with respect to TiO 2 based on SiO 2 and 29% by mass solid content) (A1), and polymer emulsion particles (B1) water shown in Reference Example 4 450 g of dispersion (solid content: 10.0% by mass) and water-dispersed colloidal silica having a number average particle size of 12 nm (trade name “Snowtex O”, manufactured by Nissan Chemical Industries, Ltd., solid content: 20% by mass) (B2) 225 g, ethanol 387.2 g, and water 903.3 g were mixed and stirred to prepare a photocatalyst composition (C-1). A glass plate having a size of 10 cm × 10 cm, in which an acrylic silicone resin was applied in advance to a thickness of 1 μm on another surface (front surface) of a glass plate on which one side (back surface) was black-printed, was prepared. The said photocatalyst composition (C-1) was apply | coated to the single side | surface (surface) of this glass plate by the bar-coat method. Then, the test plate (D-1) in which the photocatalyst coating film was formed was obtained by drying the apply | coated photocatalyst composition (C-1) for 10 minutes at 70 degreeC. Various evaluation results of this test plate (D-1) are shown in Table 1.

[Example 2]
Silica-modified titanium oxide was prepared under the same conditions as in Reference Example 1 except that the content was 5% by mass based on SiO2 with respect to TiO2. Table 1 shows [H ₂ O ₂ ], [• OH], and the amount of holes of the silica-modified titanium oxide prepared. 34.5 g of this titanium oxide as a metal oxide for photocatalyst (A2), 450 g of the polymer emulsion particle (B1) aqueous dispersion shown in Reference Example 4 (solid content 10.0% by mass), and a number average particle diameter of 12 nm 225 g of water-dispersed colloidal silica (trade name “Snowtex O”, manufactured by Nissan Chemical Industries, Ltd., solid content 20 mass%) (B2), 387.2 g of ethanol, and 903.3 g of water are mixed and stirred. Thus, a photocatalyst composition (C-2) was prepared. A glass plate having a size of 10 cm × 10 cm, in which an acrylic silicone resin was applied in advance to a thickness of 1 μm on another surface (front surface) of a glass plate on which one side (back surface) was black-printed, was prepared. The said photocatalyst composition (C-2) was apply | coated to the single side | surface (surface) of this glass plate by the bar-coat method. Then, the test plate (D-2) in which the photocatalyst coating film was formed was obtained by drying the apply | coated photocatalyst composition (C-2) at 70 degreeC for 10 minute (s). Various evaluation results of this test plate (D-2) are shown in Table 1.

[Example 3]
Table 1 shows the [H ₂ O ₂ ], [• OH], and hole amount of the platinum-modified titanium oxide prepared in Reference Example 2. 34.5 g of this titanium oxide as a metal oxide for photocatalyst (A3), 450 g of the polymer emulsion particle (B1) aqueous dispersion shown in Reference Example 4 (solid content 10.0% by mass), and a number average particle diameter of 12 nm 225 g of water-dispersed colloidal silica (trade name “Snowtex O”, manufactured by Nissan Chemical Industries, Ltd., solid content 20 mass%) (B2), 387.2 g of ethanol, and 903.3 g of water are mixed and stirred. Thus, a photocatalyst composition (C-3) was prepared. A glass plate having a size of 10 cm × 10 cm, in which an acrylic silicone resin was applied in advance to a thickness of 1 μm on another surface (front surface) of a glass plate on which one side (back surface) was black-printed, was prepared. The said photocatalyst composition (C-3) was apply | coated to the single side | surface (surface) of this glass plate by the bar-coat method. Then, the test plate (D-3) in which the photocatalyst coating film was formed was obtained by drying the apply | coated photocatalyst composition (C-3) for 10 minutes at 70 degreeC. Various evaluation results of this test plate (D-3) are shown in Table 1.

[Example 4]
Table 1 shows the [H ₂ O ₂ ], [• OH], and hole amount of the silica-modified titanium oxide prepared in Reference Example 3. 50 g of this titanium oxide as a metal oxide for photocatalyst (A4), 450 g of the polymer emulsion particle (B1) aqueous dispersion shown in Reference Example 4 (solid content 10.0% by mass), and water having a number average particle diameter of 12 nm Dispersed colloidal silica (trade name “Snowtex O”, manufactured by Nissan Chemical Industries, Ltd., solid content 20% by mass) (B2) 225 g, ethanol 383 g, and water 893 g were mixed and stirred to produce a photocatalytic composition ( C-4) was prepared. A glass plate having a size of 10 cm × 10 cm, in which an acrylic silicone resin was applied in advance to a thickness of 1 μm on another surface (front surface) of a glass plate on which one side (back surface) was black-printed, was prepared. The said photocatalyst composition (C-4) was apply | coated to the single side | surface (surface) of this glass plate by the bar-coat method. Then, the test plate (D-4) in which the photocatalyst coating film was formed was obtained by drying the apply | coated photocatalyst composition (C-4) at 70 degreeC for 10 minute (s). Various evaluation results of this test plate (D-4) are shown in Table 1.

[Comparative Example 1]
An unmodified Ishihara Sangyo Co., Ltd. anatase type titanium oxide ST-01 was used. Table 1 shows [H ₂ O ₂ ], [• OH], and the amount of holes. 10 g of this titanium oxide as a metal oxide for photocatalyst (A5), 450 g of the polymer emulsion particle (B1) aqueous dispersion shown in Reference Example 4 (solid content 10.0% by mass), and water having a number average particle diameter of 12 nm Dispersed colloidal silica (trade name “Snowtex O”, manufactured by Nissan Chemical Industries, Ltd., solid content 20% by mass) (B2) 225 g, ethanol 394 g, and water 920 g were mixed and stirred to produce a photocatalytic composition ( C-5) was prepared. A glass plate having a size of 10 cm × 10 cm, in which an acrylic silicone resin was applied in advance to a thickness of 1 μm on another surface (front surface) of a glass plate on which one side (back surface) was black-printed, was prepared. The photocatalyst composition (C-5) was applied to one side (surface) of this glass plate by a bar coating method. Then, the test plate (D-5) in which the photocatalyst coating film was formed was obtained by drying the apply | coated photocatalyst composition (C-5) for 10 minutes at 70 degreeC. Various evaluation results of this test plate (D-5) are shown in Table 1.

[Comparative Example 2]
Unmodified rutile titanium oxide MT150A manufactured by Teika Co., Ltd. was used. Table 1 shows [H ₂ O ₂ ], [• OH], and the amount of holes. 10 g of this titanium oxide as a metal oxide for photocatalyst (A6), 450 g of the polymer emulsion particle (B1) water dispersion shown in Reference Example 4 (solid content 10.0% by mass), and water having a number average particle diameter of 12 nm Dispersed colloidal silica (trade name “Snowtex O”, manufactured by Nissan Chemical Industries, Ltd., solid content 20% by mass) (B2) 225 g, ethanol 394 g, and water 920 g were mixed and stirred to produce a photocatalytic composition ( C-6) was prepared. A glass plate having a size of 10 cm × 10 cm, in which an acrylic silicone resin was applied in advance to a thickness of 1 μm on another surface (front surface) of a glass plate on which one side (back surface) was black-printed, was prepared. The said photocatalyst composition (C-6) was apply | coated to the single side | surface (surface) of this glass plate by the bar-coat method. Then, the test plate (D-6) in which the photocatalyst coating film was formed was obtained by drying the apply | coated photocatalyst composition (C-6) at 70 degreeC for 10 minute (s). Various evaluation results of this test plate (D-6) are shown in Table 1.

[Comparative Example 3]
Unmodified nitrogen-doped titanium oxide (manufactured by Ecodevice Co., Ltd.) was used. Table 1 shows [H ₂ O ₂ ], [• OH], and the amount of holes. 10 g of this titanium oxide as a metal oxide for photocatalyst (A7), 450 g of polymer emulsion particles (B1) aqueous dispersion shown in Reference Example 4 (solid content 10.0% by mass), and water having a number average particle diameter of 12 nm Dispersed colloidal silica (trade name “Snowtex O”, manufactured by Nissan Chemical Industries, Ltd., solid content 20% by mass) (B2) 225 g, ethanol 394 g, and water 920 g were mixed and stirred to produce a photocatalytic composition ( C-7) was prepared. A glass plate having a size of 10 cm × 10 cm, in which an acrylic silicone resin was applied in advance to a thickness of 1 μm on another surface (front surface) of a glass plate on which one side (back surface) was black-printed, was prepared. The photocatalyst composition (C-7) was applied to one side (surface) of this glass plate by a bar coating method. Then, the test plate (D-7) in which the photocatalyst coating film was formed was obtained by drying the apply | coated photocatalyst composition (C-7) for 10 minutes at 70 degreeC. Various evaluation results of this test plate (D-7) are shown in Table 1.

If the metal compound for photocatalysts of this invention is used, the photocatalyst layer which exhibits a required photocatalytic activity can be provided on a base coating film without the need for a protective layer. A photocatalytic coating can be provided. The photocatalyst coating film of the present invention has excellent self-cleaning properties and is useful for architectural exteriors, interior materials, exterior display applications, automobiles, displays and the like.

Claims (8)

A metal compound used as a photocatalyst, and a value of [H ₂ O ₂ ] generated when a predetermined suspension containing the metal compound is irradiated with ultraviolet light having a wavelength of 365 nm and an intensity of 5 mW / cm ² for 60 seconds has a value of 80 μM The metal compound for photocatalysts which is below and the amount of holes defined by low-temperature ESR measurement is 1.5 × 10 ¹³ or more. A metal compound used as a photocatalyst, and a value of [.OH] generated when a predetermined suspension containing the metal compound is irradiated with ultraviolet light having a wavelength of 365 nm and an intensity of 5 mW / cm ² for 60 seconds has a value of 0.2 μM The metal compound for photocatalysts which is below and the amount of holes defined by low-temperature ESR measurement is 1.5 × 10 ¹³ or more.   3. The metal compound for photocatalyst according to claim 1, wherein the metal compound is a metal oxide having a modified particle surface.   3. The metal compound for photocatalyst according to claim 1, which is a metal oxide whose particle surface is modified with silica.   The photocatalyst composition containing the metal compound for photocatalysts as described in any one of Claims 1-4, and resin.   The photocatalyst composition according to claim 5, wherein the resin includes polymer particles and particles of a metal oxide other than the metal compound for photocatalyst.   The photocatalyst coating film formed from the photocatalyst composition of Claim 5 or 6.   A photocatalyst-coated product comprising the photocatalyst coating film according to claim 7.