JP5087184B2 - One-pack type coating composition, photocatalyst used therefor, coating film thereof, and production method thereof - Google Patents

Abstract

The present invention provides a powder having sufficient photocatalytic function even under visible light, and a one-pack coating composition containing the same, the composition being adapted for direct coating onto a substrate. The powder comprises a composite wherein titanium oxide/tungsten oxide particles having nanometer-order particle diameters are fixed by being baked to a nanometer-order structure having silica as the principal component. The powder has a photocatalytic function superior to that obtained when the titanium oxide/tungsten oxide particles alone are employed as a starting material. A one-pack coating composition is obtained by blending these powders with a resin having a polysiloxane skeleton. Applying the coating composition to a variety of substrates, drying the composition, and irradiating the composition with specific light enable the titanium oxide and tungsten oxide particles to be exposed on the coating film surface. A coating film thus obtained exhibits a photocatalytic function under visible light and has an ultra-hydrophilic surface.

Description

  The present invention relates to a one-component coating composition containing a powder in which titanium oxide and tungsten oxide are fixed to a silica nanostructure and a resin having a polysiloxane skeleton, a photocatalyst powder used therefor, and a photocatalyst coating obtained therefrom. The present invention relates to a film, a superhydrophilic coating film, and a production method thereof.

  In recent years, photocatalysts such as titanium oxide have received much attention industrially because they can spontaneously decompose and detoxify dirt and harmful substances. Its application fields spread to houses, cars, medical care, land processing, etc., and are positioned as essential technologies for building a recycling-oriented society. Usually, the photocatalyst itself is a powder, and in order to use it in an actual space, it is indispensable to form a paint by mixing with a binder resin, and further to form a coating film. In order to express the catalytic activity of the coating film after it has been formed, the photocatalytic activity points (for example, titanium oxide particles) must be distributed and fixed on the coating surface, and The photocatalyst must protect the coating layer (binder) and the coated substrate. This problem is unavoidable especially when the purpose is a photocatalytic coating film mainly composed of an organic binder. That is, unless the photocatalyst coating film protects the base material as well as prevents the surface of the base material from being stained, its application is hardly expected. Therefore, various devices have been studied for the photocatalytic coating film.

  For example, it has been devised to form an undercoat film on the surface of a substrate and then form a photocatalyst-containing overcoat film thereon (see, for example, Patent Documents 1 to 4). In Patent Document 1, as an undercoat coating liquid, an alkoxysilane and an ultraviolet absorber are used, and this is applied to a substrate and then dried, and a coating liquid composed of a photocatalyst powder such as titanium oxide and a silica sol liquid is applied thereon. Thus, a method for forming a photocatalytic coating film is provided. According to this technique, weather resistance can be imparted to the base material, and the photocatalyst can be fixed to the overcoat layer, thereby providing antifouling, imparting super hydrophilicity, and the like. In Patent Document 2, a composition containing an alkoxysilane, a fluorine-based resin having a hydroxyl group in a side chain, and, if necessary, a polyfunctional isocyanate resin component as an undercoat coating solution for a transparent plastic substrate is applied to the substrate surface. There is provided a method of applying a photocatalyst composition containing titanium oxide powder thereon after coating and drying. Also, in Patent Document 3, after extending and drying a fluororesin-containing polysiloxane sol solution having strong weather resistance that does not deteriorate even with ultraviolet rays as an undercoat composition, a photocatalyst composition is applied thereon to extend the life. Photocatalytic coatings have been proposed. Furthermore, in Patent Document 4, an undercoating method for a substrate that may cause substrate surface deterioration due to the photocatalyst coating agent is also studied. Specifically, a method of applying a mist using a peroxotitanic acid aqueous solution or the like as an undercoat composition and applying a titanium oxide photocatalyst thereon has been proposed.

  It has also been devised to directly coat the photocatalytic composition on the surface of the substrate without using an undercoat film. For example, rutile type titanium oxide having low photocatalytic activity and high UV absorption ability and anatase type titanium oxide having high photocatalytic activity are mixed with an aqueous binder containing polyacrylate, polysiloxane, colloidal silica, etc., and the composition is mixed. A photocatalyst coating film is produced by directly coating the surface of the substrate (for example, see Patent Document 5). The aim of this method is to enhance the ultraviolet absorption of rutile titanium oxide and to give the function of a conventional undercoat layer.

  In fact, in the case of a photocatalyst paint, the function of titanium oxide or the like that functions as a photocatalyst deteriorates unless it is exposed on the surface. Therefore, a method for producing a photocatalyst coating that devise the cueing of titanium oxide has also been studied (see, for example, Patent Document 6). In Patent Document 6, a silicone resin paint containing a filler is applied to a substrate surface and dried to make the surface of the coating film porous. Next, a photocatalyst powder and a polymer binder are formed on the porous film. When the composition containing is applied, since the polymer binder is in a solution state, it penetrates into the porous pores, and the photocatalyst solid tends to remain on the surface, so that as much photocatalyst as possible can be picked up from the coating surface. There is a description.

  In addition, LED lighting, which has a longer life and less power consumption than fluorescent lamps, is rapidly spreading, and it is estimated that LED lighting will occupy most of indoor lighting in the near future. For this reason, in order to effectively use the photocatalyst in an indoor environment, it is essential to develop a photocatalyst of a completely visible light response type corresponding to the emission wavelength of the LED lamp.

  This LED illumination does not contain any ultraviolet rays, all emission wavelengths are visible light, and ordinary titanium oxide does not exhibit a photocatalytic function. Also, the current visible light responsive titanium oxide photocatalyst only shows weak photocatalytic activity under an LED light source.

  In recent years, attention has been focused on a tungsten oxide photocatalyst that originally has a visible light absorption ability and a photocatalytic function, instead of titanium oxide that does not have a visible light response ability. However, when the band gap is low, such as tungsten oxide, the electrons excited from the valence band to the conduction band are likely to reverse, and the structure is designed so that the electrons can be “pooled or trapped” in order to develop a catalytic function. For example, a method of supporting a transition metal on tungsten oxide has been studied (for example, see Patent Document 7). However, this transition metal-supported tungsten oxide photocatalyst has a photocatalytic activity that is about three times that of the current visible light responsive titanium oxide, and cannot be said to be satisfactory in LED lighting applications in indoor spaces. The manufacturing process of the above-mentioned tungsten oxide photocatalyst is such that tungsten oxide particles obtained in high-temperature firing are pulverized and passed through a filter to obtain tungsten oxide particles, and then a transition metal is supported on the particles. There is no structural design, and the manufacturing process is inefficient.

  As described above, various studies have been made on the visible light responsive photocatalyst, the photocatalyst coating film using the visible light photocatalyst, and the production thereof. However, each method is often cumbersome and is very complicated. As it is, even if the photocatalytic function of these coating films is sufficient, it is not suitable for practical use. In fact, the photocatalyst coating film used under room lighting is only expected to be effective, but no photocatalyst coating effective in practical use has been found yet. The only way to create a photocatalytic coating without undercoating twice is to review the design philosophy. To do so, it is essential to consider both binder design and photocatalyst design at the same time.

JP 2004-315722 A JP 2008-045052 A JP 2008-212821 A JP 2008-073588 A JP 2009-221362 A JP 2004-148143 A JP 2009-226299 A

  When considering a practical photocatalytic coating, a one-component direct coating is always required. For that purpose, it is necessary to design the photocatalyst coating film structure separately from the conventional system. The precondition here is that the photocatalyst coating itself should not deteriorate the substrate in any system, and the active site of the photocatalyst in the photocatalyst coating is the binder resin itself. It should not be hurt.

  When the above is considered comprehensively, the surface structure of the photocatalyst coating film must have an uneven structure on the nano to micron scale, and active sites that function as a photocatalyst are fixed to the convex portions. Most preferred. However, the convex part to which the photocatalytic site is fixed must not be formed of a binder resin. Furthermore, the binder resin itself must have sufficient weather resistance, and it is also necessary to firmly fix the photocatalyst.

  Therefore, the problem to be solved by the present invention is to provide a powder having a sufficient photocatalytic function even under visible light and a coating composition containing the powder and capable of being directly applied to a substrate in a one-component type. The coating film surface obtained by applying and drying the composition has a concavo-convex structure spontaneously formed, the active site of the photocatalyst is fixed on the outermost surface of the convex part, and the active site and the coating composition It is an object of the present invention to provide a simple production method capable of forming a coating film having a photocatalytic function that is not directly bonded to a binder resin in a product.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has obtained silica having titanium oxide and tungsten oxide nanoparticles baked on a high specific surface area silica nanostructure having a complex shape based on nanofibers. A paint comprising a titanium oxide composite powder photocatalyst or a silica / tungsten oxide composite powder photocatalyst mixed with a (meth) acrylate polymer resin to which a polymer chain having a polysiloxane skeleton is bonded. A coating film formed by applying a composition on a base material of any material and drying / curing has an extremely high photocatalytic function under the irradiation of sunlight and a fluorescent lamp, and a superhydrophilic function based on the structure. As a result, the present invention has been completed.

  That is, the present invention provides a powder (A1) in which titanium oxide (a1) is fixed to the silica nanostructure (a2) and / or a powder in which tungsten oxide (a3) is fixed to the silica nanostructure (a2). (A2) and a resin (B) having a polysiloxane skeleton, a one-component coating composition characterized by comprising, a photocatalytic coating film, a superhydrophilic coating film obtained by using the coating composition, and their A manufacturing method is provided.

  Furthermore, the present invention is a powdery photocatalyst comprising a composite in which titanium oxide (a1) or tungsten oxide (a3) is fixed to a silica nanostructure (a2), wherein the silica nanostructure (a2) is , Which are formed by collecting silica nanofibers or silica nanoribbons having a thickness or thickness of 10 to 100 nm and an aspect ratio of 2 or more in the range of 1 μm to 20 μm as a basic unit, and titanium oxide (a1 ) Or tungsten oxide (a3) content of 10 to 80% by mass, and a simple production method thereof.

  Usually, the titanium oxide crystal powder used as a photocatalyst has a high refractive index, reflects most of the light necessary for the photocatalytic reaction, and cannot effectively utilize the light from the light source. The photocatalyst, which is a composite of titanium oxide / silica nanostructure according to the present invention, is completely different from the conventional one, and is composed of a composite of titanium oxide nanoparticles and a silica nanostructure having a complicated shape. In this titanium oxide / silica composite photocatalyst, light is not only directly absorbed by titanium oxide but also easily scattered by the silica nanostructure, and the scattered light hits the titanium oxide fixed to the silica nanostructure. . As a result, the light absorption probability of titanium oxide at the photocatalytic activity site is increased, and as a result, the photocatalytic activity is improved. In addition, an interface at the nano level is formed between the baked titanium oxide nanoparticles and the silica nanostructure, and the nano interface also increases the function of the photocatalytic active site of titanium oxide.

  Similarly, tungsten oxide particles that have the possibility of exhibiting a photocatalytic function as a visible light responsive type are baked and fixed on the surface of the silica nanostructure, so that amorphous silica and crystalline tungsten oxide are fixed. , An interface at the nano level can be formed. This nano interface has a kind of electron pool effect, and exhibits a high quantum yield by trapping excited electrons generated by light irradiation. In the tungsten oxide / silica composite photocatalyst configured as described above, the silica nanostructure having a complicated shape causes light scattering and functions to confine photons around the catalytically active site.

  Silica nanostructures have many cavities and gaps, which effectively trap air. Silica's amorphous structure has many silanol groups, which always adsorb water molecules efficiently. Further, the surface of the silica nanostructure can effectively diffuse, adsorb and transmit the organic substance of the substrate around the catalytically active site. Therefore, the silica / tungsten oxide composite photocatalyst can function as a catalyst that efficiently decomposes an organic compound even under LED illumination light that does not contain ultraviolet rays.

  When a powder having a specific structure having such a photocatalytic function is used for coating film production, an uneven surface reflecting the structure of a complex-shaped silica nanostructure is formed, and the silica nanostructure implanted in a binder resin The body part and the silica nanostructure part protruding as the convex part integrally form a film. Therefore, light scattering is likely to occur even in the state of the coating film, and the photocatalytic active site fixed to the head of the nanostructure can function in the same state as the solid powder of the photocatalyst. This is fundamentally different from a conventional photocatalyst coating film in which a photocatalyst powder such as titanium oxide is directly bonded to a binder.

  Furthermore, since the photocatalyst coating film of this invention has the unevenness | corrugation property by a silica nanostructure in the whole film | membrane, when a photocatalyst functions, the whole film | membrane tends to become super hydrophilicity. Moreover, the photocatalyst coating film of this invention can be obtained by the simple process of apply | coating a coating composition as 1 liquid type, and drying. Therefore, the photocatalyst coating film of the present invention can be used as a highly efficient photocatalyst coating film that can be used indoors and outdoors. Further, the one-component coating composition of the present invention can be applied to glass, plastic, metal, ceramics, wood, paper, and cloth regardless of the material or shape of the substrate. Furthermore, the one-component coating composition of the present invention can be applied to necessary places in ordinary homes as well as specialists because of the ease of workability and the like, and a photocatalytic coating film can be produced. That is, the present invention provides a photocatalytic coating film that functions for preventing dirt, self-cleaning, air purification, sterilization, anti-virus, etc. even under illumination light that does not contain ultraviolet rays. It can be used comfortably in large building facilities such as homes.

4 is a SEM photograph of the silica nanostructure (a2-1) obtained in Synthesis Example 1. 3 is a SEM photograph of the silica nanostructure (a2-2) obtained in Synthesis Example 1. 4 is a SEM photograph of the silica nanostructure (a2-3) obtained in Synthesis Example 2. 4 is a SEM photograph of silica nanostructure (a2-4) obtained in Synthesis Example 2. It is a SEM photograph of the silica nanostructure (a2-5) obtained in Synthesis Example 3. It is an isotherm of nitrogen gas adsorption (lower) -desorption (upper) of the silica nanostructure (a2-6) obtained in Synthesis Example 3. It is a pore volume distribution curve of the silica nanostructure (a2-6) obtained in Synthesis Example 3. 4 is a TEM photograph of silica nanostructure (a2-6) obtained in Synthesis Example 3. It is an isotherm of nitrogen gas adsorption (lower) -desorption (upper) of the silica nanostructure (a2-7) obtained in Synthesis Example 3. It is a pore volume distribution curve of the silica nanostructure (a2-7) obtained in Synthesis Example 3. 6 is a TEM photograph of silica nanostructure (a2-7) obtained in Synthesis Example 3. 6 is a SEM photograph of tungsten oxide (a3-1) obtained in Synthesis Example 4. 7 is an X-ray diffraction pattern of tungsten oxide (a3-1) obtained in Synthesis Example 4. It is a UV-vis diffuse reflection spectrum of tungsten oxide (a3-1) obtained in Synthesis Example 4. 6 is a SEM photograph of tungsten oxide (α-1) obtained in Synthesis Example 5. 2 is a TEM photograph of powder (A1-1) obtained in Example 1. 4 is a SEM photograph of a coating film obtained in Example 4. 4 is a SEM photograph of a coating film obtained in Comparative Example 2. It is the photograph before and behind grinding | polishing (10 times) of the coating film (CA1) obtained in Example 4, and the coating film (CB1) obtained in the comparative example 2 (The photograph after grinding | polishing is CA2 and CB2, respectively). When the coating film obtained in Example 4 was polished 5,000 times with a sponge, the increase in carbon dioxide concentration due to the decomposition of acetaldehyde in the coating film before polishing (□) and the coating film after polishing (Δ) versus light irradiation It is a plot of time (irradiation conditions: black light, light quantity 1,000 lx). Dioxide by decomposition of acetaldehyde in coating film (□) obtained in Example 4, coating film (Δ) obtained in Comparative Example 2, and coating film (◯) obtained using only resin (B-1) It is a plot of the amount of increase in carbon concentration versus light irradiation time (irradiation conditions: black light, light intensity 1,000 lx). Dioxide by decomposition of acetaldehyde in coating film (□) obtained in Example 4, coating film (Δ) obtained in Comparative Example 2, and coating film (◯) obtained using only resin (B-1) It is a plot of the increase in carbon concentration versus light irradiation time (irradiation conditions: simulated sunlight, light intensity 10,000 lx). Dioxide by decomposition of acetaldehyde in coating film (□) obtained in Example 4, coating film (Δ) obtained in Comparative Example 2, and coating film (◯) obtained using only resin (B-1) It is a plot of the increase in carbon concentration versus light irradiation time (irradiation conditions: fluorescent lamp, light intensity 6,000 lx). It is a graph which shows the change of the contact angle with the time passage of the fluorescent lamp irradiation of the coating film obtained in Example 4. FIG. It is a photograph of the photobleaching reaction of the methylene blue dye when using the coating film obtained in Example 4 (irradiation conditions: fluorescent lamp, light amount 6,000 lx). 6 is a SEM photograph of the coating film obtained in Example 5. 4 is a SEM photograph of a coating film obtained in Comparative Example 3. Dioxide by decomposition of acetaldehyde in coating film (□) obtained in Example 5, coating film (Δ) obtained in Comparative Example 3, and coating film (◯) obtained using only resin (B-1) It is a plot of the increase in carbon concentration versus light irradiation time (irradiation conditions: simulated sunlight, light intensity 10,000 lx). 6 is a SEM photograph of the coating film obtained in Example 6. Dioxide due to decomposition of acetaldehyde in coating film (□) obtained in Example 6, coating film (Δ) obtained in Comparative Example 2, and coating film (◯) obtained using only resin (B-1) It is a plot of the increase in carbon concentration versus light irradiation time (irradiation conditions: simulated sunlight, light intensity 10,000 lx). It is a contact angle after three months of outdoor exposure of the coating film obtained in Example 7. (C1: before exposure after application, c2: after 1 hour after exposure, c3: after 3 months after application, d1: before exposure without application, d2: after 3 months without application) It is a plot of the increase amount of a carbon dioxide concentration by decomposition | disassembly of the acetaldehyde of the coating film produced on the various board | substrate produced in Example 8 versus light irradiation time (irradiation conditions: black light, light quantity 1,000lx). Glass (... ○ ...), wood (□), vinyl chloride plate (△), polyethylene terephthalate film (○), acrylic plate (◇), polycarbonate plate (x), polystyrene plate (+), stainless steel plate (*), Aluminum plate (■), interior wall tile (▲), outdoor tile (●), bath tile (◆), natural stone (… □…), cloth (-). It is a plot of the increase amount of carbon dioxide concentration by the acetaldehyde decomposition | disassembly of the coating film obtained in Example 4 ((square)) and Example 9 ((triangle | delta)) versus light irradiation time (irradiation conditions: artificial sunlight, light quantity 10,000lx ). Sample No. obtained in Example 10 It is a TEM photograph of T43. Sample No. obtained in Example 11 It is a TEM photograph of T53. Sample No. obtained in Example 12 It is a TEM photograph of T63. Sample No. obtained in Example 13 It is a TEM photograph of T73. Sample No. obtained in Example 14 It is a TEM photograph of T83. Sample No. obtained in Example 14 It is an X-ray diffraction pattern of T83. Sample No. obtained in Example 14 It is a UV-vis diffuse reflection spectrum of T83. Sample No. obtained in Example 15 It is a TEM photograph of T93. Sample No. obtained in Example 15 It is an X-ray diffraction pattern of T93. Sample No. obtained in Example 15 It is a UV-vis diffuse reflection spectrum of T93. Sample No. obtained in Example 16 It is a TEM photograph of T103. Sample No. obtained in Example 16 It is an X-ray diffraction pattern of T103. Sample No. obtained in Example 16 It is a UV-vis diffuse reflection spectrum of T103. It is a graph which shows the result of evaluation 1. (A3-1): □, (α-1): Δ It is a graph which shows the result of evaluation 2. Example 10: □, Example 11: Δ, Example 12: ◯, Comparative Example 3: ◇, Comparative Example 4: × It is a graph which shows the result of evaluation 3. Example 13 After firing: □, Example 13 Mixture before firing: Δ, Comparative Example 4: ○ It is a graph which shows the result of evaluation 4. Example 13: □, Comparative Example 4: Δ It is a graph which shows the result of evaluation 5. Example 14: □, Comparative Example 4: Δ It is a graph which shows the result of evaluation 6. Example 15: □, Comparative Example 4: Δ It is a graph which shows the result of evaluation 7. Example 16: □, Comparative Example 4: Δ It is a graph which shows the result of evaluation 8. Example 10: □, Comparative Example 4: Δ It is a graph which shows the result of evaluation 9. Example 10: □, Comparative Example 4: Δ 2 is a SEM photograph of the coating film obtained in Example 18. 2 is a SEM photograph of the coating film obtained in Example 20. 2 is a SEM photograph of the coating film obtained in Example 22. It is a graph which shows the result of the coating-film evaluation 11. Example 18: □, Example 20: Δ, Example 22: × It is a graph which shows the result of the coating-film evaluation 12. Example 18: □, Example 20: Δ, Example 22: ×

  Photocatalytic coatings have a history of nearly 20 years. In particular, photocatalytic coatings for outdoor (ultraviolet) applications have a self-cleaning effect due to dirt prevention and super hydrophilicity, and photocatalytic coatings using titanium oxide powder are rarely applied to high-rise buildings and large buildings. Yes. However, when considering indoor use or a detached house, the photocatalyst's active path cannot be expanded simply by incorporating a photocatalyst in the form of crystal powder of titanium oxide into the coating film structure. Tungsten oxide, which is known to absorb visible light and decompose organic substances, separates charges into electrons and holes when irradiated with visible light energy, but because of its low energy gap, Since recombination is likely to occur, it is difficult to say that it has a stable photocatalytic function. Even if it is formed into a coating film, it does not become a photocatalytic coating film that is effective in the long term.

  To develop a photocatalyst coating film, first, there must be a photocatalyst designed for the construction of the coating film. Therefore, the present invention has devised a structural design for expressing the function as a photocatalyst several times higher than that of ordinary titanium oxide crystal powder itself. It is a composite photocatalyst obtained by baking titanium oxide or tungsten oxide nanoparticles on a silica nanostructure. Such a composite type photocatalyst tends to cause a light confinement effect, improves the light utilization efficiency of the photocatalytically active site, and at the same time forms a nanointerface between titanium oxide or tungsten oxide nanoparticles and silica nanostructures. , Improve the photocatalytic function.

  Usually, a catalyst is not only a simple active site, but can function as a catalyst by designing the structure around the active site and by cooperating the whole. Even in photocatalysts containing titanium oxide or tungsten oxide as an active ingredient, the precise structure design allows the charge separation state to be maintained for a long time, the generation of active oxygen from the reduction of oxygen by the separated electrons, and the C—H by holes. Generation of radical hydroxyl groups by direct oxidation of bonds and oxidation of water can be expected. In other words, the photocatalyst is not composed only of the active sites of titanium oxide or tungsten oxide, but rather functions to “diffuse and confine light” around it, that is, the function of “photon concentration”, oxygen and moisture in the air. “Oxygen and water concentration” function that traps around the catalytic activity site, “scaffolding” function that efficiently diffuses and accumulates substrate organic substances around the catalytic activity site, nano-interface structure that promotes activation of the catalytic activity site, etc. A structure that satisfies the various elements must be constructed.

  When the composite photocatalyst of the present invention is used for coating film formation, the photocatalyst itself is not embedded in the binder resin, and the surface of the photocatalytically active site can be easily recognized by forming irregularities due to the silica nanostructure on the surface. You can make it out. This is equivalent to making the photocatalyst float in the air from the binder, and maximizes the photocatalytic function on the surface of the coating film. To develop a photocatalytic coating film, a chemical structural element integrated with the photocatalyst in the binder resin and strong weather resistance are required. For this purpose, a hybrid resin in which an inorganic component is contained in a normal organic polymer is required. In the present invention, a new concept of a photocatalyst coating film is proposed based on a photocatalyst design and a binder resin design that satisfy the above requirements. The present invention will be described in detail below.

[Titanium oxide (a1)]
The titanium oxide (a1) used in the present invention is not particularly limited, and may be any crystal phase of anatase, rutile, or anatase / rutile mixed crystal, and a metal is contained in the titanium oxide crystal. Titanium oxide doped with ions, nitrogen atoms or the like may be used.

  Moreover, in order to fix titanium oxide (a1) on the silica nanostructure (a2) described later efficiently, it is preferable to use fine titanium oxide powder of 10 to 100 nm.

[Silica nanostructure (a2)]
The silica nanostructure (a2) used in the present invention is produced by using a sol-gel reaction of an alkoxysilane, which is a silica precursor, using a crystalline association formed by a polymer having a linear polyethyleneimine skeleton in an aqueous medium as a template. To do. Specifically, the present inventors have already made JP 2005-264421, JP 2005-336440, JP 2006-63097, JP 2006-306711, JP 2007-51056, JP 2009- Any silica nanostructure provided in No. 24124 can be used as the silica nanostructure (a2) of the present invention. These silica nanostructures (a2) are different from general macro-size silica such as silica gel, and are characterized by having basic units of the order of nanometers as structural units, which are assembled in a three-dimensional space. . The silica nanostructures provided in these patent documents may contain metal ions or metal nanoparticles, but these do not inhibit the photocatalytic function (depending on the metal species). It also has an effect of enhancing the photocatalytic function) and can be suitably used as the silica nanostructure (a2) used in the present invention as it is.

  As a production method, for example, a polymer having a linear polyethyleneimine skeleton is suspended in water and dissolved at a temperature around 80 ° C. After confirming the dissolution of the polymer, it is allowed to cool to room temperature (25-30 ° C.). The basic unit of nanofibers, nanoribbons, nanonanofibers, etc., depending on the overall structure of the polymer having a linear polyethyleneimine skeleton and other coexisting substances (metal ions, acidic compounds, etc.) A precipitate which is an aggregate is obtained. By mixing an ethanol solution containing about 20 wt% of a silica source such as tetraalkoxysilane (including condensate), silica is uniformly deposited on the basic unit having various structures of a polymer having a polyethyleneimine skeleton. In addition, the silica nanostructure having the polymer unit inside can be obtained by forming an association between the basic units.

  In addition, when the above polymer having a linear polyethyleneimine skeleton is dissolved by heating at 80 ° C., other polymers such as polyethylene glycol are mixed to obtain precipitates having different shapes as basic units. It is also possible to use a silica nanostructure having a complicated shape obtained by depositing silica in the same manner on polyethyleneimine in the precipitate.

  Moreover, as a method for dissolving the polymer having the above-mentioned linear polyethyleneimine skeleton in water, not only dissolution by heating but also dissolution by acid addition is possible. In this method, by adding a basic compound after dissolution and adjusting the pH to about 8, a nanocrystal of a polymer having a linear polyethyleneimine skeleton can be precipitated. When mixed, a silica nanostructure having a complicated shape can be obtained.

  Silica nanostructures obtained by these methods are characterized by having nanometer-order structures as basic units, which are aggregated into a micro size.

  Specifically, the silica nanostructure (a2) is a fiber-like structure (hereinafter referred to as nanofiber) having a thickness of 10 to 100 nm, preferably 20 to 80 nm, and an aspect ratio of 2 or more, preferably 5 or more. Or a ribbon-like structure having a thickness of 10 to 100 nm, preferably 15 to 50 nm, and a value of 2 or more, preferably 5 or more when the length with respect to the thickness is an aspect ratio. The body (hereinafter referred to as nanoribbon) is the basic unit. And the magnitude | size (longest part when observed with a TEM image) of the aggregate | assembly which aggregates this basic unit as a structural unit is 1 micrometer-20 micrometers normally, Preferably it is 3-15 micrometers.

  In addition, the polymer having a linear polyethyleneimine skeleton used as a template and present in the silica nanostructure prepared by the above method can be removed by baking the structure at 400 to 900 ° C. It is. At this time, since the overall shape does not change before and after firing, a silica nanostructure having silica as a main constituent can be obtained. In addition, the fact that silica is the main constituent means that a component obtained by carbonization of the polymer may remain depending on the firing temperature, atmosphere, etc., but in the case where the third component is not intentionally used, it does not contain components other than silica. It shows that. In the present invention, the above-described silica nanostructure (composite) containing a polymer chain or the silica nanostructure from which the polymer chain has been removed by firing can be suitably used.

[Powder (A1) composed of a composite in which titanium oxide (a1) is fixed to silica nanostructure (a2)]
Fixation of titanium oxide (a1) to the silica nanostructure (a2) can be easily and reproducibly performed by “adsorption” and subsequent “calcination”. Specifically, first, dispersion / mixing and physical adsorption are performed by suspending the powder of silica nanostructure (a2) and the powder of titanium oxide (a1) in an aqueous medium. At this time, it is preferable to perform stirring and dispersion by ultrasonic treatment, a stirrer, or the like.

  Usually, the surface of silica is strongly polar due to the presence of many OH groups, and the surface of titanium oxide is also highly polar for the same reason. Therefore, the titanium oxide (a1) powder can be physically adsorbed on the surface of the silica nanostructure (a2) by removing the supernatant aqueous solution by centrifugation or the like after stirring and dispersing treatment and performing a drying treatment. it can.

  The use ratio of the titanium oxide (a1) powder and the silica nanostructure (a2) is preferably 10/95 to 80/20 as the mass ratio represented by (a1) / (a2), more preferably. Is in the range of 30/60 to 50/50.

  The amount of the aqueous medium used when mixing titanium oxide (a1) and silica nanostructure (a2) is not particularly limited, but is the total mass of titanium oxide (a1) and silica nanostructure (a2). On the other hand, a mass ratio of 10 to 30 times is preferable.

  The aqueous medium may be water alone or a mixed solvent with various hydrophilic organic solvents, and examples thereof include ethanol, 2-propanol, and acetone.

  When mixing the titanium oxide (a1) and the silica nanostructure (a2) in an aqueous medium, a basic polymer may be used in combination in order to further ensure adsorption. Examples of the basic polymer that can be used at this time include polyamines such as polyethyleneimine, polyallylamine, polyvinylamine, and polylysine.

  The detailed method of the adsorption step by mixing the titanium oxide (a1) and the silica nanostructure (a2) is not particularly limited. For example, after mixing at a constant ratio, the room temperature (20-30 ° C.) Can be sufficiently adsorbed by stirring for 1 to 24 hours.

  A composite in which titanium oxide (a1) is fixed to silica nanostructure (a2) by heating and firing the structure obtained above by adsorbing titanium oxide (a1) powder to silica nanostructure (a2) The powder (A1) which consists of is obtained.

  When the used silica nanostructure (a2) has already been removed from the inner polymer chain, the heating and firing temperature may be in the temperature range of 350 to 900 ° C., and the silica nanostructure in which the polymer chain exists is present. When the structure (a2) is used, it is fired at a temperature of 400 ° C. or higher for the purpose of simultaneously removing the polymer chain.

  The firing time is usually 2 to 8 hours, and it is preferable to control the temperature rise programmatically. For example, stepwise firing is preferable, for example, raising from room temperature to 300 ° C. over 1 hour, then raising to 500 ° C. over 30 minutes, and holding at that temperature for 3 hours.

  The temperature increase program affects the photocatalytic activity of the powder (A1) composed of the silica nanostructure after the titanium oxide sintered and fixed, and the program is adjusted each time depending on the type of titanium oxide (a1) to be fixed. It is preferable to do. For example, when sintering and fixing titanium oxide doped with carbon or nitrogen, in order to maintain the doped structure, it is desirable to set the maximum temperature at the temperature rise to 500 ° C. or less, and 450 ° C. or less is more preferable. desirable. Moreover, when the titanium oxide crystal to be fixed is already a mixed crystal state of two crystals of anatase and rutile, it is preferable to set the maximum temperature in firing to 600 ° C. or lower.

  Moreover, although it is preferable to perform a heat-firing process in an air atmosphere, it can also be performed in inert gas, for example, nitrogen atmosphere.

  The content of titanium oxide (a1) after firing is basically determined by the amount of adsorbed titanium oxide (a1), and can be adjusted in the range of 10 to 80% by mass.

  In the powder (A1) composed of the silica nanostructure to which the titanium oxide (a2) obtained by the above production method is fixed, what kind of bonding interface is formed between the crystal of the titanium oxide (a1) and the silica nanostructure (a2)? It is unclear, but since the catalytic activity cannot be improved without performing the calcination treatment, a certain degree of improvement in the photocatalytic activity can be seen even in a silica system having no complicated shape such as silica gel. ) And silica nanostructure (a2) at the junction interface, it is presumed that a high light confinement effect and an organic substance concentration effect (concentration of the photodegradable organic substance in the vicinity of the photocatalytic active site) at the nanointerface are manifested. .

  The powder (A1) composed of a composite obtained by fixing the titanium oxide (a1) obtained by the above-described method to the silica nanostructure (a2) exhibits its function as a photocatalyst as it is. The activity of the powder (A1) in a composite state of titanium oxide (a1) and silica nanostructure (a2) is several times higher than that of a catalyst containing titanium oxide alone. For example, in the decomposition reaction of acetaldehyde, when compared with a unit weight catalyst amount, a system using titanium oxide of the same weight even though much less titanium oxide was contained in a certain amount of composite photocatalyst. This doubles the photocatalytic activity.

  The powder (A1) thus obtained exhibits high catalytic activity with various light sources such as sunlight, xenon lamp, mercury lamp, halogen lamp, black light, fluorescent lamp and the like.

[Powder (A2) composed of a composite in which tungsten oxide (a3) is fixed to silica nanostructure (a2)]
Conventionally, the production of tungsten oxide powder uses a tungstate, and specifically, a method of firing a precursor obtained by using various tungstates as solutions and drying them. Since this precursor does not have a specific periodic structure, particle growth is caused by firing to form a large bulk body. It is difficult to fix the bulk tungsten oxide powder to the surface of the silica nanostructure (a2).

  In the present invention, a method for controlling the growth to such a bulk body was examined, and the following steps were found as a method for fixing the particles of tungsten oxide (a3) to the silica nanostructure (a2).

  The first method is to prepare a dispersion of the aforementioned silica nanostructure (a2) (the polymer may be present inside or removed by calcination and silica may be the main constituent). , Tungstate (a3 ′) is mixed, and tungstate (a3 ′) is adsorbed in silica nanostructure (a2), and then baked at 900 ° C. or lower to form silica nanostructure (a2). Tungsten oxide (a3) particles are fixed.

  When the dispersion liquid in which the silica nanostructure (a2) is dispersed in the medium and the tungstate (a3 ′) which is the source of the tungsten oxide (a3) are mixed in the medium, the titanium oxide (a1) is mixed. Similarly, the tungstate (a3 ′) is adsorbed and concentrated on the surface of the silica nanostructure (a2). When firing in this state, the tungstate (a3 ′) adsorbed on the surface becomes tungsten oxide (a3). However, since the location is fixed, the growth of particles is controlled, and nano-sized oxidation is performed. Tungsten (a3).

  The tungstate (a3 ′) that can be used here is not particularly limited as long as it becomes tungsten oxide by firing, and examples thereof include ammonium tungstate, sodium tungstate, and calcium tungstate. It is preferable to use ammonium metatungstate from the viewpoint of easy availability of industrial raw materials and the viewpoint that counter ions can be removed by firing.

  Usually, the surface of silica is strongly polar due to the presence of many OH groups. Therefore, the dispersion obtained by dispersing the silica nanostructure (a2) in the medium and the tungstate (a3 ′) which is the source of the tungsten oxide (a3) are stirred and dispersed in the medium, and then centrifuged. Thus, when the supernatant aqueous solution is removed and drying treatment is performed, a powder in which the tungstate (a3 ′) is adsorbed on the surface of the silica nanostructure (a2) is obtained.

  The use ratio of tungstate (a3 ′) to silica nanostructure (a2) is the ratio of tungsten oxide (a3) after firing to silica nanostructure (a2) after firing, that is, (a3) / ( It is preferable to use it so that it may become 10 / 95-80 / 20 as mass ratio represented by a2), More preferably, it is the range of 30 / 60-50 / 50.

  The amount of the medium used when mixing the tungstate (a3 ′) and the silica nanostructure (a2) is not particularly limited, but the tungstate (a3 ′) and the silica nanostructure (a2) It is suitable if it is in the range of 10 to 30 times by mass ratio with respect to the total mass.

  The medium may be water alone or a mixed solvent with various hydrophilic organic solvents, and examples thereof include ethanol, 2-propanol, and acetone.

  When the tungstate (a3 ') and the silica nanostructure (a2) are mixed in a medium, a polyamine may be used in combination in order to ensure more adsorption. That is, a method may be used in which polyamine is mixed in a dispersion of silica nanostructure (a2) and adsorbed thereon, and then tungstate (a3 ′) is mixed.

  Examples of the polyamine include polyethyleneimine, polyallylamine, polyvinylamine, and polylysine, and these may be used alone or in combination of two or more.

  The detailed method of the adsorption step by mixing the tungstate (a3 ′) and the silica nanostructure (a2) is not particularly limited, and for example, after mixing at a constant ratio, it is allowed to move to room temperature (20-30). The mixture can be sufficiently adsorbed by stirring at 1 ° C. for 1 to 24 hours.

[Baking process]
The powder of tungsten oxide (a3 ') adsorbed to the silica nanostructure (a2) obtained above is fired and fired to fix the tungsten oxide (a3) particles to the silica nanostructure (a2). Is done.

  When the silica nanostructure (a2) from which the internal polymer chain has already been removed is used, the heating and baking temperature may be in the temperature range of 350 to 900 ° C., and the silica nanostructure (a2 in which the polymer chain exists) ) Or when polyamine is used in combination, it is preferable to perform firing at a temperature of 600 ° C. or higher for the purpose of simultaneously removing these organic substances. Note that, at a temperature exceeding 900 ° C., the silica starts to melt, the structure of the silica nanostructure (a2) may be destroyed, and particle growth of tungsten oxide (a3) may occur. The upper limit is 900 ° C.

  The firing time is usually 2 to 8 hours, and it is preferable to control the temperature rise programmatically. For example, stepwise firing is preferable, for example, raising from room temperature to 300 ° C. over 1 hour, then raising to 500 ° C. over 30 minutes, and holding at that temperature for 3 hours.

  Moreover, although it is preferable to perform a heat-firing process in an air atmosphere, it can also be performed in inert gas, for example, nitrogen atmosphere.

  The content of tungsten oxide (a3) after firing is basically determined by the amount of adsorbed tungstate (a3 ') and can be adjusted in the range of 10 to 80% by mass.

[Method for Producing Tungsten Oxide (a3) Particles and Method for Producing Powder (A2) Using the Same]
Moreover, by preparing particles of tungsten oxide (a3) in advance and physically adsorbing the particles to silica nanostructure (a2) and then firing, the particles of tungsten oxide (a3) are applied to silica nanostructure (a2). Fixing can also be performed. That is, a polymer having a linear polyethyleneimine skeleton is associated in an aqueous medium, and an aqueous solution of tungstate (a3 ′) is further mixed to associate the polymer with tungstic acid or tungstate (a3 ′). When this is heated and fired, particles of tungsten oxide (a3) can be obtained. When this is adsorbed to the silica nanostructure (a2) by the same method as described above, The powder (A2) of the invention can be obtained.

  The method for obtaining the polymer aggregate having a linear polyethyleneimine skeleton is the same as the method for obtaining the silica nanostructure (a2). After obtaining a polymer aggregate, instead of silica source, tungstate (a3 ′), which is a source of tungsten oxide, is mixed in an aqueous medium, and the polymer and tungstate (a3 ′) or tungstic acid are mixed. Can be obtained.

  At this time, as a use ratio of the polymer and the tungstate (a3 ′), the molar ratio of the ethyleneimine unit and the tungstate (a3 ′) in the polymer is within a range of 95/5 to 20/80. It is preferable from the viewpoint that the combination of the two is surely performed.

  The mixing of the polymer and the tungstate (a3 ') is carried out in an aqueous medium. The concentration at this time is preferably in the range of 0.01 to 10.0% by mass as the concentration of the polymer. The aqueous medium may be water alone or a mixed solvent of a hydrophilic solvent such as alcohols and water, but it is necessary that the aggregate of the polymer does not dissolve or is difficult to dissolve. .

  In addition, when obtaining an aggregate of a polymer having a linear polyethyleneimine skeleton, the form of the aggregate can be controlled by adding a metal ion or an organic acid.

  Compounding of a polymer having a linear polyethyleneimine skeleton and tungstate (a3 ′) or tungstic acid proceeds rapidly, but stirring is performed at room temperature (20 to 30 ° C.) for about 1 to 24 hours. Is preferred.

  The complex thus obtained becomes a precipitate. This is isolated and then heated and fired to obtain tungsten oxide (a3) nanoparticles (particles having an average particle size on the order of nanometers). The baking temperature is preferably 500 to 800 ° C. The firing time is usually 2 to 8 hours, and it is preferable to control the temperature rise programmatically. For example, stepwise firing is preferable, for example, raising from room temperature to 300 ° C. over 1 hour, then raising to 500 ° C. over 30 minutes, and holding at that temperature for 3 hours. The heating and baking process is preferably performed in an air atmosphere, but the process may be performed in an inert gas, for example, a nitrogen atmosphere to leave the polymer.

  The nanoparticles of tungsten oxide (a3) obtained by the above method have a larger specific surface area than that prepared by precipitating tungstate (a3 ′) by simple drying and firing, and, for example, ultraviolet rays Even if it does not contain LED illumination light, it exhibits photocatalytic activity. This is presumably because the growth of tungsten oxide is controlled by the self-organizing effect of the polymer. By fixing the tungsten oxide (a3) nanoparticles thus obtained to the silica nanostructure (a2) in the same manner as described above, the photocatalytic action is further activated.

  The method for producing the powder (A2) by fixing the tungsten oxide (a3) nanoparticles obtained above to the silica nanostructure (a2) is basically the same as described above. That is, the tungsten oxide (a3) nanoparticles obtained by the above-described method and the silica nanostructure (a2) are mixed in an aqueous medium, and the tungsten oxide (a3) nanoparticles are mixed with the silica nanostructure (a2). After adsorbing to the surface, removing the supernatant by centrifugation or the like and performing a drying treatment, the resultant is baked.

  The use ratio of the silica nanostructure (a2) and the tungsten oxide (a3) nanoparticles is not particularly limited, but the mass ratio represented by the former / the latter is 95/10 to 20/80. If it is within the range, it is preferable because adsorption proceeds rapidly.

  The amount of the aqueous medium used when mixing the silica nanostructure (a2) and the tungsten oxide (a3) nanoparticles is not particularly limited, but is 10 to 30 times the total mass of the solid content. An amount is preferred.

  The aqueous medium may be water alone or a mixed solvent of a hydrophilic medium and water such as alcohols. At this time, it is also possible to promote adsorption by using a polyamine together as described above.

  The method for mixing the silica nanostructure (a2) and the tungsten oxide (a3) particles is not particularly limited, and after mixing them at a constant ratio, the mixture is made at room temperature (20 to 30 ° C.) for 1 It is sufficient to stir for ~ 24 hours.

[Baking process]
By heating and firing the powder obtained above, in which the tungsten oxide (a3) nanoparticles are adsorbed on the silica nanostructure (a2), the tungsten oxide (a3) particles are formed on the silica nanostructure (a2). Fixed.

  The heating and baking temperature may be in the temperature range of 350 to 900 ° C. when the silica nanostructure (a2) from which the inner polymer chain is already removed is used, and the structure (a2) in which the polymer chain exists inside When is used, firing is preferably performed at a temperature of 600 ° C. or higher for the purpose of simultaneously removing the polymer chain. Note that, at a temperature exceeding 900 ° C., the silica starts to melt, the structure of the silica nanostructure (a2) may be destroyed, and particle growth of tungsten oxide (a3) may occur. The upper limit is 900 ° C.

  The firing time is usually 2 to 8 hours, and it is preferable to control the temperature rise programmatically. For example, stepwise firing is preferable, for example, raising from room temperature to 300 ° C. over 1 hour, then raising to 500 ° C. over 30 minutes, and holding at that temperature for 3 hours.

  Moreover, although it is preferable to perform a heat-firing process in an air atmosphere, it can also be performed in inert gas, for example, nitrogen atmosphere.

  The content of tungsten oxide (a3) after firing is basically determined by the amount of adsorbed tungsten oxide (a3) particles, and can be adjusted in the range of 10 to 80% by mass.

  In the powder (A2) comprising the silica nanostructure (a2) to which the tungsten oxide (a3) is fixed in the present invention, what kind of bonding interface is formed between the tungsten oxide (a3) particles and the silica nanostructure (a2). Although it is unclear whether the catalytic activity is improved without performing the calcination treatment, a high pool effect of excited electrons, light at the junction interface between tungsten oxide (a3) and silica nanostructure (a2). It is presumed that a confinement effect and an organic substance concentration effect are manifested.

[Photocatalytic function]
The powder (A1) or powder (A2) obtained by the above-mentioned method is effective alone in the decomposition reaction of the organic substance, and the light source used is any one of sunlight and fluorescent lamps. Also good. In particular, the powder (A2) formed by compounding tungsten oxide has responsiveness and activity even under the LED illumination light that does not include near-ultraviolet light (including only visible light). In a high point, the application range is wider than the conventional photocatalyst.

  In the present invention, as a method for measuring the activity of the powder (A1) or the powder (A2), the powder is allowed to stand in a glass reaction vessel in which a volatile organic compound (VOC) gas having a constant concentration is sealed. By irradiating the reactor with visible light / LED light, it can be estimated from the change with the light irradiation time of the carbon dioxide concentration generated by the oxidative decomposition of the volatile organic compound gas.

  When the activity of the photocatalyst is measured by the above-described method, the concentration of the volatile organic compound to be used may be 50 to 500 ppm, and the amount of the powder having a catalytic action is 5 to 100 mg / kg based on the reactor volume. A 500 mL range is preferable.

  The volatile organic compound is not particularly limited, and low molecular organic substances in general can be used. Furthermore, if it can adhere to the surface of a photocatalyst such as an organic compound other than a low-molecular compound, such as an organic dye or a polymer, it can be decomposed by light irradiation. For example, the photocatalyst can be measured by measuring the degree of coloration of the organic dye. The activity of can be measured.

  The light irradiation time varies depending on the concentration of the organic substance used or the structure thereof, but is preferably in the range of 1 hour to 1 day.

  In particular, the powder (A2) formed by combining tungsten oxide functions sufficiently as a photocatalyst even when the light amount of the LED light source alone is very low (for example, the amount of indoor illumination is around 500 lx). Can do. The powders (A1) and (A2) of the present invention can function as a photocatalyst even under various light sources such as a single light source containing ultraviolet rays, such as a xenon lamp, a mercury lamp, a halogen lamp, and a fluorescent lamp. . As a matter of course, the photocatalyst of the present invention functions as a photocatalyst, even if it is not direct light, but also sunlight or room light reflected or scattered by various light source illuminations.

[Resin having polysiloxane skeleton (B)]
In the coating composition in the present invention, the resin used as the binder may be a resin (B) having a polysiloxane skeleton, and the side chain of a part of the monomer residue of the polymer composed of the (meth) acrylate monomer. A resin obtained by bonding a polymer having a polysiloxane skeleton is preferable. Examples of the resin (B) having such a structure include a SERATE series product manufactured by DIC Corporation. Or it can also synthesize | combine according to the method disclosed by Unexamined-Japanese-Patent No. 10-36514, Unexamined-Japanese-Patent No. 2006-328354, and international publication WO2010 / 067742.

  For example, hydrolyzable silicon compound of trialkoxyalkyl (phenyl) silane, or hydrolyzable silicon compound of trialkoxyalkyl (phenyl) silane, dialkoxydialkyl silanes, tetraalkoxy silanes A polysiloxane having a hydroxyl group and / or hydrolyzable group bonded to a silicon atom, and a (meth) acrylate copolymer having both a hydrolyzable silyl group and an acid group. A dispersion or solution of an aqueous resin obtained by dispersing or dissolving a resin obtained by subjecting a polymer to a partial neutralization or complete neutralization with a basic compound and then dispersing or dissolving in water can be used. .

  Alternatively, the polysiloxane, a hydrolyzable silyl group and acid group, and a (meth) acrylate copolymer having both other functional groups are subjected to a condensation reaction, and then partially neutralized with a basic compound. Alternatively, a dispersion or solution of an aqueous resin obtained by dispersing or dissolving a resin obtained by complete neutralization in water can be used.

  More simply, in the method for synthesizing the aqueous resin (B), a functional group of trialkoxysilane is included in the side chain of some monomer residues in the (meth) acrylate copolymer, among others. And the side chain of the copolymer is mixed with a trialkoxysilane functional group and alkoxysilanes and subjected to a hydrolytic condensation reaction, whereby a polysiloxane is added to the side chain of the (meth) acrylate copolymer. Are combined.

As specific examples, the following reactions can be taken up.
The reaction vessel was charged with 470 g of isopropanol and heated to 80 ° C. under nitrogen gas. Next, at the same temperature, 100 g of styrene, 300 g of methyl methacrylate, 334 g of n-butyl methacrylate, 186 g of n-butyl acrylate, 30 g of 3-methacryloyloxypropyltrimethoxysilane, 50 g of acrylic acid and tert-butylperoxy-2-ethylhexano 50 g of ate is mixed with 450 g of isopropanol and added dropwise to 470 g of isopropanol prepared in the reaction vessel over 4 hours. After completion of the dropwise addition, the mixture is stirred at the same temperature for 16 hours to obtain a copolymer having both a carboxyl group and a trimethoxysilyl group having a nonvolatile content of 53.5% and a number average molecular weight of 10,000 or more.

  A mixture of 1480 g of the copolymer, 354 g of phenyltrimethoxysilane and 365 g of isopropanol is heated to 80 ° C. Next, a mixture of 2.9 g of isopropyl acid phosphate and 96 g of ion-exchanged water is added dropwise at the same temperature over 5 minutes, and the mixture is stirred at the same temperature for 4 hours to produce a resin having a polysiloxane structure. Next, 54 g of triethylamine and 1,050 g of ion-exchanged water are added dropwise at the same temperature over 30 minutes. Thereafter, isopropanol as a solvent is removed by distillation under reduced pressure to obtain an aqueous resin (B) having a nonvolatile content of 42.3%. The aqueous resin (B) obtained in this way can be cured only by drying at room temperature after coating. Moreover, after mixing with the alkoxysilane silane compound, it can be cured by coating and drying.

  Thus, the coating film obtained by room temperature dry-curing shows strong weather resistance. For example, even after exposure for 2,000 hours with a sunshine weatherometer, the coating film does not deteriorate, cracks do not occur, and surface glossiness of 90% or more can be maintained. From this, the said water-based resin (B) can be used suitably as a binder resin of a photocatalyst.

  The resin (B) having a polysiloxane skeleton used in the present invention may be an active energy ray-curable resin. The content of the polysiloxane skeleton at this time is an ultraviolet curable resin capable of forming a cured coating film having excellent durability in a range of 10 to 95% by mass based on the mass of the resin (B). It is preferable because it can be obtained, more preferably 30 to 95% by mass, and still more preferably 30 to 75% by mass.

  Such a resin (B) can be produced by various methods, and among them, it is preferably produced by the methods shown in the following (1) to (3).

  (1) A polymer segment containing a silanol group and / or a hydrolyzable silyl group is prepared in advance, and this polymer segment is combined with a silanol group and / or a hydrolyzable silyl group and a polymerizable double bond. A method in which a hydrolytic condensation reaction is performed by mixing the silane compound.

  (2) A polymer segment containing a silanol group and / or a hydrolyzable silyl group is prepared in advance. In addition, polysiloxane is prepared in advance by hydrolytic condensation reaction of a silane compound having both a silanol group and / or a hydrolyzable silyl group and a polymerizable double bond. And the method of mixing a polymer segment and polysiloxane and performing a hydrolytic condensation reaction.

  (3) A method in which the polymer segment, a silane compound having both a silanol group and / or a hydrolyzable silyl group and a polymerizable double bond, and polysiloxane are mixed and subjected to a hydrolytic condensation reaction.

  The hydrolysis-condensation reaction in the production process of the resin (B) shown in the above (1) to (3) can proceed by various methods, but by supplying water and a catalyst in the production process. A method for allowing the reaction to proceed is simple and preferred.

  The hydrolysis condensation reaction means that a part of the hydrolyzable group is hydrolyzed under the influence of water or the like to form a hydroxyl group, and then proceeds between the hydroxyl groups or between the hydroxyl group and the hydrolyzable group. Refers to a proceeding condensation reaction.

  Examples of the polymer segment containing a silanol group and / or a hydrolyzable silyl group include, for example, an acrylic polymer containing a silanol group and / or a hydrolyzable silyl group, a silanol group and / or a hydrolyzable silyl group. Fluoroolefin polymer containing, vinyl ester polymer containing silanol group and / or hydrolyzable silyl group, aromatic vinyl polymer containing silanol group and / or hydrolyzable silyl group, silanol group and / or Silanol groups such as polyolefin polymers containing hydrolyzable silyl groups and / or vinyl polymers containing hydrolyzable silyl groups, polyurethane polymers containing silanol groups and / or hydrolyzable silyl groups, silanol groups And / or contains hydrolyzable silyl groups Polyester polymer that can be used polyether polymer such as a silanol group and / or a hydrolyzable silyl group. In particular, it is preferable to use a vinyl polymer containing a silanol group and / or a hydrolyzable silyl group or a polyurethane polymer containing a silanol group and / or a hydrolyzable silyl group, and the silanol group and / or hydrolyzable. It is more preferable to use an acrylic polymer containing a silyl group.

  When an acrylic polymer is used as the polymer segment containing the silanol group and / or hydrolyzable silyl group, the acrylic resin is, for example, a vinyl monomer containing a silanol group and / or a hydrolyzable silyl group. And, if necessary, can be obtained by polymerizing with other vinyl monomers.

  Examples of the vinyl monomer containing a silanol group and / or a hydrolyzable silyl group include vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinyltri (2-methoxyethoxy) silane, and vinyltrimethyl. Acetoxysilane, vinyltrichlorosilane, 2-trimethoxysilylethyl vinyl ether, 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropyltriethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane , 3- (meth) acryloyloxypropyltrichlorosilane and the like. Among these, vinyltrimethoxysilane and 3- (meth) acryloyloxypropyltrimethoxysilane are preferable because the hydrolysis reaction can easily proceed and by-products after the reaction can be easily removed.

  Examples of other vinyl monomers used as necessary include acrylic monomers. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2 -Alkyl (meth) acrylates having an alkyl group having 1 to 22 carbon atoms such as ethylhexyl (meth) acrylate and lauryl (meth) acrylate; aralkyl such as benzyl (meth) acrylate and 2-phenylethyl (meth) acrylate (Meth) acrylates; cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; ω-alkoxy such as 2-methoxyethyl (meth) acrylate and 4-methoxybutyl (meth) acrylate Alkyl (meth) acrylates; aromatic vinyl monomers such as styrene, p-tert-butylstyrene, α-methylstyrene, vinyltoluene; vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, etc. Carboxylic acid vinyl esters; alkyl esters of crotonic acid such as methyl crotonic acid and ethyl crotonic acid; dialkyl esters of unsaturated dibasic acids such as dimethyl malate, di-n-butyl malate, dimethyl fumarate, dimethyl itaconate Α-olefins such as ethylene and propylene; fluoroolefins such as vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene and chlorotrifluoroethylene; alkyl vinyl ethers such as ethyl vinyl ether and n-butyl vinyl ether; Cycloalkyl vinyl ethers such as pentyl vinyl ether and cyclohexyl vinyl ether; tertiary amide group-containing singles such as N, N-dimethyl (meth) acrylamide, N- (meth) acryloylmorpholine, N- (meth) acryloylpyrrolidine and N-vinylpyrrolidone Examples of the polymers.

  When a vinyl polymer is used as the polymer segment, the vinyl polymer is produced by polymerizing by various polymerization methods such as a bulk radical polymerization method, a solution radical polymerization method, and a non-aqueous dispersion radical polymerization method. be able to. When the resin (B) is dissolved in an organic solvent to obtain an ultraviolet curable resin composition, it is preferable to radically polymerize the vinyl monomer in an organic solvent to obtain a vinyl polymer.

  Examples of the organic solvent include aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, n-octane, cyclohexane, and cyclopentane; aromatic hydrocarbons such as toluene, xylene, and ethylbenzene. Alcohols such as methanol, ethanol, n-butanol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether; ethyl acetate, n-butyl acetate, n-amyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, etc. Esters of; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, cyclohexanone; diethylene glycol dimethyl ether, diethylene glycol dibutyl ether Polyalkylene glycol dialkyl ethers; ethers such as 1,2-dimethoxyethane, tetrahydrofuran, dioxane, etc .; N-methylpyrrolidone, dimethylformamide, dimethylacetamide or ethylene carbonate are used alone or in combination of two or more. be able to.

  In addition, when the vinyl monomer is polymerized by radical polymerization, a polymerization initiator can be used as necessary. Examples of such polymerization initiators include 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), and 2,2′-azobis (2-methylbutyronitrile). ) And the like; tert-butyl peroxypivalate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide, diisopropyl peroxide Peroxides such as oxycarbonate can be used.

  The polymer segment is preferably a polymer segment having a number average molecular weight of 500 to 200,000, more preferably a polymer segment having a number average molecular weight of 700 to 100,000, and a number average molecular weight of 1,000 to 50,000. 000 polymer segments are particularly preferred. By using a polymer segment having a number average molecular weight within such a range, it is possible to prevent thickening and gelation during production of the resin (B), and to obtain a coating film having excellent durability. A resin composition can be obtained.

  By using a polymer segment having a polymerizable double bond group as the polymer segment constituting the resin (B) used in the present invention, a more durable cured coating film can be formed. For example, a polymer segment having a carboxyl group is used as the polymer segment having a polymerizable double bond, and a compound having both a polymerizable double bond and an epoxy group, such as glycidyl methacrylate, is added and reacted therewith. Can be obtained.

  Examples of the silane compound containing a silanol group and / or hydrolyzable silyl group and a silane compound having a polymerizable double bond used in the method (1) include vinyltrimethoxysilane, vinyltriethoxysilane, and vinyl. Methyldimethoxysilane, vinyltri (2-methoxyethoxy) silane, vinyltriacetoxysilane, vinyltrichlorosilane, 2-trimethoxysilylethyl vinyl ether, 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropyl Examples include triethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane, and 3- (meth) acryloyloxypropyltrichlorosilane.

  As the silane compound having both a silanol group and / or a hydrolyzable silyl group and a polymerizable double bond, a hydrolysis condensation reaction can easily proceed, and a by-product after the reaction can be easily removed. Since it is possible, it is preferable to use vinyltrimethoxysilane and 3- (meth) acryloyloxypropyltrimethoxysilane.

  If necessary, the silane compound used in the method (1) may be used in combination with another silane compound other than the silane compound having both the silanol group and / or hydrolyzable silyl group and the polymerizable double bond. good.

  Examples of the other silane compounds include methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-butoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, iso-butyltrimethoxysilane, and cyclohexyltrimethoxysilane. , Various organotrialkoxysilanes such as phenyltrimethoxysilane and phenyltriethoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi-n-butoxysilane, diethyldimethoxysilane, diphenyldimethoxysilane, methylcyclohexyldimethoxysilane or methyl Various diorganodialkoxysilanes such as phenyldimethoxysilane; methyltrichlorosilane, ethyltrichlorosilane, phenyltrichloro Orchids, vinyl trichlorosilane, dimethyl dichlorosilane, chlorosilane such as diethyl dichlorosilane or diphenyl dichlorosilane and the like.

  As the other silane compounds, organotrialkoxysilanes and diorganodialkoxysilanes that can easily undergo hydrolysis reaction and easily remove by-products after the reaction are preferable.

  Moreover, as said other silane compound, tetrafunctional alkoxysilane compounds, such as tetramethoxysilane, tetraethoxysilane, or tetra n-propoxysilane, and the partial hydrolysis-condensation product of this tetrafunctional alkoxysilane compound can also be used together. When the tetrafunctional alkoxysilane compound or a partially hydrolyzed condensate thereof is used in combination, the silicon atom of the tetrafunctional alkoxysilane compound is 20 mol% with respect to all silicon atoms constituting the polysiloxane segment. It is preferable to use together so that it may become the range which does not exceed.

  Such a resin (B) has many silanol (Si—OH) groups derived from the polysiloxane skeleton. This functional group can be dehydrated and condensed with silanol groups on the silica surface when mixed with the silica powder. This property is an important structural element in the photocatalytic coating design in the present invention.

[One-pack type coating composition containing powder (A1) and / or powder (A2) and resin (B)]
The one-component coating composition of the present invention includes a powder (A1) comprising a composite in which nanoparticles of titanium oxide (a1) are fixed to the silica nanostructure (a2), and / or the silica nanostructure. Powder (A2) composed of a composite in which nanoparticles of tungsten oxide (a3) are fixed to (a2) and resin (B) having a polysiloxane skeleton can be easily prepared in a medium. .

  When preparing the coating composition, first, the powder (A1) and / or (A2) is mixed in the medium, and the mixture is stirred by a high shearing dispersion device such as a homomixer to obtain a dispersion of the photocatalyst powder. Is preferably prepared. Next, the dispersion obtained in this way and the dispersion or solution of the resin (B) are mixed and stirred at room temperature (20 to 30 ° C.) for 1 to 3 hours to obtain a uniformly dispersed coating composition.

  During the preparation of the coating composition, a solvent or the like used for synthesizing the resin (B) or adjusting the dispersion or solution thereof can be mixed.

  The solid content (nonvolatile content) that is the sum of the powder (A1) and / or the powder (A2) in the coating composition and the resin (B) is preferably in the range of 10 to 80 wt%. However, it is desirable to prepare appropriately according to the use conditions and purpose.

  The composition ratio of the powder (A1) and / or the powder (A2) and the resin (B) in the nonvolatile content of the coating composition is the sum of the powder (A1) and the powder (A2). The ratio of use with the resin (B) is preferably in the range of 10/90 to 80/20 by mass ratio represented by [(A1) + (A2)] / (B). In order to improve the density of the coating film surface of the site, it is more preferable to adjust the mass ratio in the range of 35/65 to 65/35.

  In the coating composition of the present invention, pigments, dyes and the like can be mixed to form a colored coating. The amount of the pigment or dye used can be adjusted according to the color shade, but is preferably 50% by mass or less of the resin (B).

  When the one-component coating composition obtained above is allowed to stand for more than a day, the photocatalyst powder in the composition tends to sink, but it is stable again for several hours by gently stirring or shaking the liquid. A dispersed state can be maintained. In addition, when the composition is stored at room temperature for half a year or more, the photocatalyst powder may sink, or the entire composition does not gel at all, and can be suitably used even after long-term storage. .

[Production of photocatalytic coating film]
The photocatalyst having extremely high photocatalytic ability and weather resistance can be obtained by applying the one-component coating composition obtained above to an arbitrary substrate of arbitrary shape, drying it under a seasonal environmental temperature, and irradiating with light. A coating film can be obtained.

  The method for applying the coating composition to the substrate is not particularly limited and can be appropriately applied according to the intended use. As an application method, methods such as bar coating, spin coating, brushing, spraying, screen printing, and gravure printing can be taken up.

  The film thickness of the photocatalyst coating film formed by coating using the coating composition is preferably in the range of 1 μm to 30 μm.

  Coating film curing by coating using the above-described coating composition can be cured in the range of seasonal environmental temperature (5-35 ° C.) to 200 ° C. The curing at the seasonal environmental temperature here is actually only drying, and the drying time is preferably 5 to 24 hours. In the case of heat curing, the higher the temperature, the shorter the curing time, and it is preferably in the range of several minutes to several hours.

  Various silane compounds can be mixed and used in the coating composition of the present invention. Examples of the silane compound include methyltrimethoxylane, methyltriethoxylane, ethyltrimethoxylane, ethyltriethoxysilane, n-propyltrimethoxylane, n-propyltriethoxysilane, iso-propyltrimethoxysilane, iso- Propyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycitoxypropyltrimethoxysilane, 3-glycitoxypropyltriethoxysilane, 3 -Aminopropyltrimethoxysilane, 3-aminopropyltriethoxylane, 3-mercaptopropyltomethoxysilane, 3-mercaptotriethoxysilane, 3,3,3-trifluoropropyltrimethoxy 3,3,3-trifluoropropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxylane, p-chloromethylphenyltrimethoxy Orchid, p-chloromethylphenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxycyan and the like.

  It is also possible to add a photopolymerization initiator to the coating composition and cure it by UV irradiation. When using what has a polymerizable double bond in resin (B) especially, it is preferable to perform active energy ray hardening. In that case, the hardening process of a coating film can also be performed in an air atmosphere or inert gas, for example, nitrogen atmosphere.

  The surface of the coating film immediately after the composition is applied to the substrate and cured has a concavo-convex structure, but the cueing photocatalytic activity site (site where titanium oxide or tungsten oxide nanoparticles are present) is also present. Since the resin (B) which is a binder resin is adhered, it does not function as a photocatalyst coating film as it is. In order to function as a photocatalyst coating film, it is necessary to irradiate the cured coating film with light and decompose the resin adhering to the photocatalytic activity site by light irradiation. The light irradiation method is not limited to a special light source, and it is sufficient to leave the coated film in an outdoor or indoor natural light environment. In particular, when exposed to sunlight in the outdoors, the photocatalytic function of the coating film can be effectively exhibited by irradiation for 1 hour or longer. In the case of indoor natural light, the photocatalytic function of the coating film is effectively expressed after several hours or after one day.

  When developing a photocatalyst for the coating film, a black light, a fluorescent lamp, a high-pressure mercury lamp, a xenon lamp, or the like can be suitably used if a specific light source is necessary for the work. The light irradiation time by these light sources depends on the intensity of the light source lamp, but in the case of high-intensity, high-pressure mercury lamps, xenon lamps, etc., irradiation for 1 hour or more is sufficient, and in the case of black lights and fluorescent lamps with low intensity Irradiation in the 5-24 hour range is preferred.

[Photocatalytic coating]
The photocatalytic coating film obtained through each of the above steps has a basic structure in which a photocatalytic active site is found on the surface, and a silica nanostructure that supports the heading is implanted in a continuous layer of the coating. This is like a structure in which only the head of the octopus (photocatalytically active site) is exposed on the outer surface and the foot extends and spreads over a continuous layer of the coating. Since the Si—OH functional group of the silica nanostructure (a2) equal to the octopus foot is dehydrated and condensed with the Si—OH functional group in the resin (B) which is the binder resin, a Si—O—Si bond is formed. The silica nanostructure (a2) corresponding to the octopus foot is integrated with the binder layer to form a coating film. Therefore, the photocatalyst coating film according to the present invention is characterized in that all the constituent components (photocatalyst and resin) are chemically bonded.

  The thickness of the photocatalyst coating film of the present invention can be prepared in the range of 2 to 50 μm. In order to improve the catalytic activity, substrate adhesion, weather resistance, etc. of the photocatalytic coating film, it is desirable to adjust the thickness of the coating film to 5 to 20 μm.

  Moreover, the photocatalyst coating film of this invention can also be made into a colored state. As for coloring, it is desirable that the pigment or dye is embedded in the binder resin layer of the coating film. In this state, since the pigment component is in a state where it is separated from the cueing photocatalytic active site without contact, it is not decomposed by the photocatalyst (titanium oxide or tungsten oxide).

The surface of the photocatalyst coating film of the present invention is composed of a concavo-convex structure, but the convex portion of the head is a hydrophilic inorganic component TiO ₂ / SiO ₂ , WO ₃ / SiO ₂ , which is on the entire film surface. It has spread. Therefore, the surface is easy to get wet with water, and even if a water drop is dropped, it spreads on the surface of the film, and the water contact angle is kept at 5 ° or less. That is, it exhibits super hydrophilicity.

  The photocatalytic coating film showing super hydrophilicity of the present invention can effectively decompose volatile organic compounds (VOC) into carbon dioxide. Volatile organic compounds are decomposed under outdoor or indoor natural light, and are also decomposed under fluorescent lamps and LED lighting lamps. When a specific light source is used, volatile organic compounds (toxic gases) can be effectively decomposed under irradiation of a high-pressure mercury lamp, a xenon lamp, a halogen lamp, or a black light.

  EXAMPLES Hereinafter, although an Example and a reference example demonstrate this invention further more concretely, this invention is not limited to these. Unless otherwise specified, “%” represents “mass%”.

[Titanium oxide and aqueous resin]
In this example, P25 manufactured by Nippon Aerosil Co., Ltd. was used as titanium oxide (a1) [hereinafter referred to as titanium oxide (a1-1)]. As resin (B) having an aqueous polysiloxane skeleton, DIC Corporation Ceranate WSA-1070 [hereinafter referred to as resin (B-1)] was used.

〔Scanning electron microscope〕
The scanning electron microscope used was VE-9800 manufactured by KEYENCE.

[UV-vis reflection spectrum]
For the UV-vis reflection spectrum, a USB-4000 spectroscope and DH-2000 lamp manufactured by Ocean Optics were used.

[X-ray diffraction method (XRD)]
Place the sample on the holder for the measurement sample, set it on the Rigaku wide-angle X-ray diffractometer “Rint-ultma”, Cu / Kα ray, 40 kV / 30 mA, scan speed 1.0 ° / min, scan range 20 It was performed under the condition of ˜40 °.

[Structural observation by transmission electron microscope]
The transmission electron microscope was a TEM2200FS manufactured by JEOL, and the measurement was performed under the condition of a voltage of 200 keV.

[Specific surface area measurement by BET method]
The specific surface area was measured by using a TriStar made by SHIMADZU and using the BET method. The pore size distribution was estimated from a plot of pore volume fraction versus pore size.

[Titanium oxide / tungsten oxide content measurement by fluorescent X-ray spectrum]
X-ray fluorescence measurement was performed under vacuum conditions using ZSX manufactured by Rigaku Corporation.

[Photocatalytic activity evaluation]
The photocatalytic activity was evaluated from the change over time in the amount of carbon dioxide generated in the oxidative decomposition reaction of acetaldehyde in a gas phase reaction. The acetaldehyde gas was used at simulated sunlight, 500 ppm under black light irradiation, and 200 ppm under fluorescent lamp irradiation. The powdered photocatalyst was used in an amount of 0.2 g, the photocatalyst coating having a size of 10 cm ² was used, and light irradiation was performed in a state of being enclosed in a 500 mL glass reactor. The amount of light was about 10,000 lx for simulated sunlight (SOLAX SET-140F), about 1,000 lx for black light (FL10BL-B made by Panasonic), and about 6000 lx for fluorescent light (FL-10D made by Panasonic). LED lighting was performed under irradiation of about 20,000 lx using an E-CORE LEL-BR9N-F type manufactured by Toshiba Corporation. The amount of carbon dioxide generated was investigated by connecting a photoacoustic multi-gas monitor type 1312 manufactured by INNOVA to a photoreactor with a tetrahydrofuran tube.

  The photocatalyst antifouling functionality on the surface of the coating film was evaluated by a decolorization reaction rate test of a methylene blue dye (manufactured by Tokyo Kasei Co., Ltd.) that is commonly used for photocatalytic film antifouling evaluation. The concentration of the methylene blue test solution used was 30 ppm. One drop was dropped on the photocatalyst coating, and after natural drying, evaluation was performed under irradiation with a fluorescent lamp. The light quantity of the fluorescent lamp was about 6,000 lx.

  For the evaluation of the superhydrophilic function of the photocatalyst coating film, irradiation with black light was performed for 12 hours after the coating film was formed. This was done by observing a decrease in the water contact angle with the lamp (light quantity of about 6,000 lx) irradiation time.

Synthesis Example 1 [Production of Silica Nanostructures (a2-1) and (a2-2)]
Silica nanostructures were produced by the methods disclosed in patent documents (Japanese Patent Laid-Open Nos. 2005-264421, 2005-336440, 2006-063097, and 2007-051056).

<Synthesis of linear polyethyleneimine (P5K)>
5 g of commercially available polyethyloxazoline (number average molecular weight 500,000, average polymerization degree 5,000, manufactured by Aldrich) was dissolved in 20 mL of 5 M aqueous hydrochloric acid solution. The solution was heated to 90 ° C. in an oil bath and stirred at that temperature for 10 hours. Acetone 50 mL was added to the reaction solution to completely precipitate the polymer, which was filtered and washed three times with methanol to obtain a white polyethyleneimine powder. When the obtained powder was identified by ¹ H-NMR (heavy water), peaks 1.2 ppm (CH ₃ ) and 2.3 ppm (CH ₂ ) derived from the side chain ethyl group of polyethyloxazoline completely disappeared. It was confirmed that That is, it was shown that polyethyloxazoline was completely hydrolyzed and converted to polyethyleneimine.

  The powder was dissolved in 5 mL of distilled water, and 50 mL of 15% aqueous ammonia was added dropwise to the solution while stirring. The mixture was allowed to stand overnight, the precipitated powder was filtered, and the powder was washed 3 times with cold water. The washed powder was dried in a desiccator at room temperature (25 ° C.) to obtain linear polyethyleneimine (P5K). The yield was 4.5 g (containing crystallization water). In polyethyleneimine obtained by hydrolysis of polyoxazoline, only the side chain reacts and the main chain does not change. Therefore, the polymerization degree of P5K is the same as 5,000 before hydrolysis.

<Synthesis of silica nanostructure>
A certain amount of P5K was mixed in distilled water, heated to 90 ° C. to obtain a transparent solution, and then prepared as a 3% aqueous solution as a whole. The aqueous solution was naturally cooled to room temperature (25 ° C.) to obtain a pure white P5K aggregate dispersion. While stirring, 70 mL of an ethanol solution (volume concentration 50%) of TMOS (tetramethoxysilane) was added to 100 mL of the aggregate dispersion, and stirring was continued at room temperature for 1 hour. The deposited precipitate was filtered, washed with ethanol three times, and dried under heating at 40 ° C. to obtain 15 g of powder. FIG. 1 shows an SEM photograph of the obtained powder. The powder was confirmed to have a bundle structure with nanofibers as the basic unit. This is designated as silica nanostructure (a2-1).

From the thermogravimetric loss analysis (TG / DTA6300 made by SII Nano Technology Inc) of the silica nanostructure (a2-1) obtained in this way, it was confirmed that the polymer content was 7 wt%. In addition, the specific surface area was measured (Flow Sorb II 2300 manufactured by Micrometrics), and as a result, it was 112 m ² / g.

<Manufacture of silica nanostructure (a2-2) by heating and firing>
The silica nanostructure (a2-1), which is a composite of the polymer and silica obtained above, was fired at 600 ° C. for 1 hour to obtain a silica nanostructure from which the polymer component had been removed. FIG. 2 shows an SEM photograph of the silica nanostructure after firing. The obtained silica nanostructure was found to be an aggregate of nanofibers composed of silica without any change in shape or the like even during the firing treatment. Moreover, it was 315 m < ² > / g as a result of measuring a specific surface area. Let the powder obtained above be a silica nanostructure (a2-2).

Synthesis Example 2 [Production of Silica Nanostructures (a2-3) and (a2-4)]
Polyethyloxazoline was hydrolyzed in the same manner as in the first stage of <Synthesis of linear polyethyleneimine> in Synthesis Example 1 to obtain a hydrochloride of linear polyethyleneimine. 5 g of this hydrochloride was dissolved in 90 mL of distilled water, and 29.5 mL of a 1.4 mol / L aqueous ammonia solution was mixed with the solution while stirring. The mixture was stirred for 12 hours, and then 12.5 mL of a 1.4 mol / L aqueous ammonia solution was added dropwise in 5 portions every 10 hours, followed by stirring for 1 hour to obtain a white precipitate. The deposited precipitate was washed three times by centrifugation. After washing, the obtained powder was dispersed in 120 mL of distilled water. 15 mL of methyl silicate (MS51) was added to the dispersion and stirred at room temperature (20-25 ° C.) for 4 hours. The reaction solution was treated by centrifugation, and the precipitated solid was washed with ethanol and dried at room temperature to obtain a composite composed of polyethyleneimine and silica. Yield: 9.7g. In FIG. 3, the SEM photograph of the obtained composite_body | complex was shown. It can be confirmed that the aggregate has a nanosheet structure. From XRD, a peak derived from a crystal of linear polyethyleneimine was observed. This is designated as silica nanostructure (a2-3).

<Manufacture of silica nanostructure (a2-4) by heating and firing>
0.5 g of the nanosheet-like silica nanostructure (a2-3) obtained in the above step was added to an alumina crucible and fired in an electric furnace. The furnace temperature was raised to 800 ° C. over 1 hour and held at that temperature for 2 hours. This was naturally cooled to remove the polymer component to obtain a powder. The specific surface area of the powder thus obtained was 319.0 m ² / g. FIG. 4 shows an image photograph of SEM observation. The nanosheets overlapped and the structure did not change after baking at 800 ° C. Let the powder which is an aggregate | assembly of this nanosheet be a silica nanostructure (a2-4).

Synthesis Example 3 [Production of Silica Nanostructures (a2-5) and (a2-6)]
<Preparation of polyethylenimine hydrochloride aqueous solution, crystallization, synthesis of composite nanofiber>
Polyethyloxazoline was hydrolyzed in the same manner as in the first stage of <Synthesis of linear polyethyleneimine> in Synthesis Example 1 to obtain a hydrochloride of linear polyethyleneimine. 5 g of this hydrochloride was dissolved in 60 mL of distilled water, and 10 mL of a 5 mol / L sodium hydroxide solution was added dropwise to the solution while stirring. The pH of this mixed solution was 9.0. After stirring the mixed solution for 4 hours, the precipitated aggregate was washed three times by centrifugation. The washed powder was dispersed in 500 mL of distilled water. At this time, the pH value of the dispersion was 6.5. 5.5 mL of methyl silicate (MS51) was added to the dispersion and stirred at room temperature (20-25 ° C.) for 1 hour. The reaction solution was treated by centrifugation, and the precipitated solid was washed with water and then dried at room temperature to obtain a composite consisting of polyethyleneimine and silica. Yield: 10.8g. In FIG. 5, the SEM photograph of the obtained composite_body | complex was shown. It can be confirmed that the structure is a collection of fibers. From XRD, a peak derived from a crystal of linear polyethyleneimine was observed. This is designated as silica nanostructure (a2-5).

<Production of nanotube-like silica nanostructure (a2-6)>
The silica nanostructure (a2-5) obtained above (0.5 g) was immersed in 10 mL of methanol for 1 hour, filtered, and the solid content was dried at room temperature. As a result, the silica nanostructure (a2-6), which is a nanotube-like composite in which the linear polyethyleneimine inside is dissolved and adsorbed on the inner surface of the silica surrounding it, and the fiber core disappears, is obtained. It was. The obtained silica nanostructure (a2-6) was used for surface analysis measurement. The BET surface area was 286 m ² / g. Its isotherm and pore distribution are shown in FIGS. 6 and 7, respectively. As a result of the pore size distribution, a sharp peak appeared at a pore size of 3.5 nm. This peak value just reflects the tube inner size. The pore size increases from 2 nm, decreases after a peak value at 4 nm or less. This strongly suggests that a regular hollow structure, that is, a tube is formed in the fibrous silica. Further, from TEM observation, it was confirmed that straightly stretched fibers having a thickness of 12 nm or less overlap closely to form a sheet and that the center portion of the fiber appears transparent (FIG. 8). That is, the central part is a cavity and the inner diameter is 3 to 4 nm. From the thermal analysis, the weight loss was 25.3 wt%.

<Production of silica nanostructure (a2-7) by firing silica nanostructure (a2-6)>
0.5 g of the silica nanostructure (a2-6), which is a nanotube-like composite obtained in the above step, was added to an alumina crucible and fired in an electric furnace. The furnace temperature was raised to 800 ° C. over 1 hour and held at that temperature for 2 hours. This was naturally cooled to remove the polymer component to obtain a powder.

The specific surface area of the powder thus obtained was 418.5 m ² / g. The isotherm and pore size distribution of this powder are shown in FIGS. 9 and 10, respectively. The pore size decreases from 2 nm, increases from around 3 nm, and decreases again after the peak value. This just reflects the tube bore size. FIG. 11 shows an image photograph of TEM observation. The nanofiber overlap structure did not change even after baking at 800 ° C. The hollow size (4.2 nm) in the pore size distribution almost coincided with the inner diameter (4 nm) in the TEM observation. This nanotube-shaped powder is referred to as silica nanostructure (a2-7).

[Production of tungsten oxide particles]
Synthesis Example 4 <Production of Tungsten Oxide (a3-1) Particles Using Linear Polyethyleneimine>
0.43 g of the linear polyethyleneimine powder obtained in Synthesis Example 1 was suspended in 100 ml of distilled water and dissolved by stirring at 80 ° C. for 1 hour. After confirming the dissolution of the polymer, the mixture was allowed to cool at room temperature (20 to 25 ° C.) for 30 minutes to obtain a polyethyleneimine precipitate having nanofibers as a basic structure. 6.0 ml of ammonium metatungstate aqueous solution (NV.50% aqueous solution manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) was added to the aqueous dispersion of the obtained precipitate, and the mixture was stirred for 1 hour. Distilled water was removed using a centrifuge and further dried at 120 ° C. for 12 hours using a vacuum dryer. The dried powder was heated in an air atmosphere from room temperature to 300 ° C. using an electric furnace for 30 minutes, held at 300 ° C./1 hour, then raised to 600 ° C. over 30 minutes, and held at that temperature for 30 minutes. After that, it was naturally cooled. The surface of the powder thus obtained was examined using an SEM and confirmed to be tungsten oxide particles of 100 nm or less (FIG. 12). When the crystal structure was examined by XRD, it was confirmed to be tungsten oxide having a high crystallinity (FIG. 13). Furthermore, the absorbance spectrum was measured using the UV-vis reflection spectrum, and it was confirmed that the absorption spectrum had a large absorption in the visible light region up to about 520 nm (FIG. 14). Moreover, it was 9.0 m ^<-2 > / g in the specific surface area measurement by BET method. The tungsten oxide particles thus obtained are designated as (a3-1).

Synthesis Example 5 <Production of tungsten oxide particles by a drying method>
Distilled water was removed from a 10 ml ammonium metatungstate aqueous solution in a 50 ml eggplant flask using a rotary evaporator, and the resulting precipitate was dried at 120 ° C. for 12 hours using a vacuum dryer. The dried powder was heated in an air atmosphere from room temperature to 300 ° C. using an electric furnace for 30 minutes, held at 300 ° C./1 hour, then raised to 600 ° C. over 30 minutes, and held at that temperature for 30 minutes. After that, it was naturally cooled. By this firing program, tungsten oxide powder was obtained. When the surface of the obtained powder was observed by SEM, it was confirmed that it was a bulk body on the order of micrometers (FIG. 15). Moreover, it was 3.2 m ^<-2 > / g in the specific surface area measurement by BET method. The tungsten oxide particles thus obtained are defined as (α-1).

Synthesis Example 6 <Synthesis of Resin (B-2) Having Polysiloxane Skeleton>
A resin having a polysiloxane skeleton was synthesized by a method disclosed in a patent document (International Publication WO2010 / 067672).

  Into a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, a condenser tube and a nitrogen gas inlet, 191 g of phenyltrimethoxysilane (PTMS) was charged and heated to 120 ° C. Subsequently, a mixture consisting of 169 g of methyl methacrylate (MMA), 11 g of 3-methacryloyloxypropyltrimethoxysilane (MPTS), and 18 g of tert-butylperoxy-2-ethylhexanoate (TBPEH) was added into the reaction vessel for 4 hours. It was dripped over. Thereafter, the mixture was stirred at the same temperature for 16 hours to prepare a vinyl polymer having a trimethoxysilyl group.

Next, the temperature of the reaction vessel is adjusted to 80 ° C., and 131 g of methyltrimethoxysilane (MTMS), 226 g of 3-acryloyloxypropyltrimethoxysilane (APTS), and 116 g of dimethyldimethoxysilane (DMDMS) are introduced into the reaction vessel. Added. Thereafter, a mixture of 6.3 g of iso-propyl acid phosphate and 97 g of deionized water made by Sakai Chemical Co., Ltd. was dropped in 5 minutes and stirred at the same temperature for 2 hours to cause a hydrolytic condensation reaction. The product was obtained. When the reaction product was analyzed by ¹ H-NMR, almost 100% of the trimethoxysilyl group of the vinyl polymer was hydrolyzed. Thereafter, the reaction product is distilled under a reduced pressure of 10 to 300 mmHg for 2 hours under the condition of 40 to 60 ° C. to remove the generated methanol and water, so that the nonvolatile content is 99.4%. 600 g of a resin (B-2) composed of a polysiloxane segment and a vinyl polymer segment was obtained.

Example 1 <Synthesis of Powder (A1-1) as Composite Photocatalyst of Silica Nanostructure and Titanium Oxide>
10.5 g of the silica nanostructure (a2-1) containing the linear polyethyleneimine obtained above and 0.45 g of titanium oxide (a1-1) powder are suspended in 30 ml of distilled water and subjected to ultrasonic irradiation. After performing for 1 hour, the supernatant distilled water was removed with a centrifugal separator, and the solid content was dried with a vacuum dryer at 120 ° C. for 2 hours. The dried powder was heated from room temperature to 300 ° C. over 30 minutes in an air atmosphere using an electric furnace, held at 300 ° C. for 1 hour, and then heated to 600 ° C. over 30 minutes. After holding for 30 minutes, it was naturally cooled. By this firing program, powder (A1-1) in which titanium oxide (a1-1) and silica nanostructure (a2-1) were combined was obtained. FIG. 16 shows a TEM photograph of the obtained powder (A-1). It was confirmed that the titanium oxide (a1-1) nanoparticles were bonded and bonded on the silica nanofibers to form a protruding portion.

Example 2 <Preparation of one-component coating composition: medium water>
1.5 g of the powder (A1-1) obtained in Example 1 was suspended in 30 mL of distilled water, and a rotational speed of 40 m / s was obtained using a mixer-type disperser film mix (PRIMIX model 40-40). For 30 seconds. The powder (A1-1) and the resin (B-1) having an aqueous polysiloxane skeleton are mixed so that the solid content mass ratio (A1-1) / (B-1) is a ratio shown in Table 1. Ultrasonic irradiation was performed for 1 hour to obtain a one-component coating composition.

Example 3 <Preparation of one-component coating composition: medium isopropanol>
In Example 2, a one-component coating composition shown in Table 2 was prepared in the same manner as in Example 2 except that the medium was isopropanol.

Comparative Example 1 <Preparation of Mixture of Titanium Oxide and Aqueous Resin: Medium Water>
Except for using titanium oxide (a1-1) as it is, after being dispersed in distilled water in the same manner as in Example 2, the solid content mass ratio (a1) of titanium oxide (a1-1) and resin (B-1) -1) / (B-1) was mixed so as to have the ratio shown in Table 3, and ultrasonic irradiation was performed for 1 hour to obtain a comparative aqueous coating composition.

Example 4 <Formation of a photocatalytic coating film by application of a one-component coating composition on a glass substrate>
No. 2 obtained in Example 2. A one-component coating composition of T14 was applied on a glass substrate using an applicator (manufactured by YOSHIMITU) at a speed of 10 and an RDS16 bar coater. The prepared coating film was left to stand overnight at room temperature (25 ° C.) and then irradiated with black light for 5 hours to obtain a photocatalyst coating film. The SEM observation image of this photocatalyst coating film was shown in FIG. The image that the surface uneven structure derived from the shape of the silica nanostructure spreads over the entire film can be confirmed. On the surface of the silica nanofiber appearing on the surface layer, particles appearing white are visible. These grains are nanoparticles of titanium oxide (a1-1) in a cueing state.

Comparative Example 2
For comparison, the coating composition No. obtained in Comparative Example 1 was used. A coating film was prepared with a bar coater in the same manner using T34, and allowed to stand and dry overnight at room temperature. As a result of observing the coating film using the titanium oxide particles as they were with an SEM, unlike Example 4, it was not possible to confirm any complex shape, and a smooth coating film was formed (Fig. 18). It can be confirmed that the titanium oxide particles are embedded in the binder layer. Further, no cracks were observed in the coating film obtained in Example 4, but clear cracks were observed in the coating film of Comparative Example 2. Because of these differences, in the coating film of Example 4, the silica nanostructure in the powder (A1-1) is strongly bonded to the polysiloxane in the resin (B) to form a network structure, and the coating film strength. It is suggested to improve.

<Evaluation of coating film 1: Abrasion resistance test 1>
The coating film obtained in Example 4 and Comparative Example 2 was tested for wear resistance. FIG. 19 shows the result of manual polishing using a paper waste (Kimwipe) manufactured by Nippon Paper Crecia Co., Ltd. 10 times. Even if the coating film of Example 4 was polished, no phenomenon such as peeling was observed, but in the coating film of Comparative Example 2, a clear peeling phenomenon was confirmed. This strongly suggests that the silica nanostructure is strongly bonded to the binder resin and improves the physical strength of the coating film.

<Coating evaluation 2: abrasion resistance test 2>
The coating film obtained in Example 4 and Comparative Example 2 was tested for wear resistance. Assuming applications that are generally used at home as a wear material, performance was evaluated in repeated rubbing tests of sponges (Duskin's kitchen sponge antibacterial type N, material: ester-based urethane foam / polyester nonwoven fabric). . The tester used HEIDON reciprocating wear tester TYPE30S, and applied 5,000 times with a load of 10 g, and the change in photocatalytic activity before and after polishing was evaluated. In the coating film obtained in Example 4, it was confirmed from the photocatalytic activity before and after the polishing that no deterioration was observed on the surface of the coating film even after polishing 5,000 times (FIG. 20). On the other hand, the coating film obtained in Comparative Example 2 was peeled off by 10 Kimwipe polishing. This strongly suggests that the coating film in the present application is extremely robust and practical compared with the conventional photocatalyst coating film.

<Evaluation of coating film 3: Photocatalytic activity under black light irradiation>
The photocatalytic activity of the coating film obtained by applying the coating film obtained in Example 4 and Comparative Example 2 and the resin (B-1) to a glass substrate as it was in Example 4 and drying it was determined to be black light. Evaluation was performed under irradiation (FIG. 21). Although the content rate of titanium oxide in the coating film of Example 4 is a small amount of titanium oxide as compared with the coating film of Comparative Example 2, the decomposition rate of acetaldehyde is extremely high. When converted from the fact that the actual amount of titanium oxide in the coating film of Example 4 is 35 wt% of the titanium oxide contained in the coating film of Comparative Example 2, the catalytic activity of titanium oxide was improved by about 6 times. .

<Coating evaluation 4: Photocatalytic activity under simulated sunlight irradiation>
The coating film obtained in Example 4 and Comparative Example 2 and the aqueous resin (B-1) were applied to a glass substrate as it was in Example 4 and dried to simulate the photocatalytic activity of the coating film obtained. Evaluation was performed under sunlight irradiation (FIG. 22). The coating film of Example 4 showed high catalytic activity under simulated sunlight irradiation as well as under black light irradiation. This suggests that the coating film of the present invention can be applied to outer wall coating in real space.

<Evaluation of coating film 5: Photocatalytic activity under fluorescent lamp irradiation>
The photocatalytic activity of the coating film obtained in Example 4 and Comparative Example 2 and the coating film obtained by applying the aqueous resin (B-1) to a glass substrate as it was in Example 4 and drying it was generally Evaluation was performed under white fluorescent irradiation widely used in the home (FIG. 23). Similar to the above evaluation results, the coating film of Example 4 exhibited extremely high photocatalytic activity even under fluorescent lamp irradiation. This strongly suggests that the coating film of the present invention has high utility not only in the coating for the outer wall but also in the indoor space.

<Coating film evaluation 6: Super hydrophilic performance under fluorescent lamp irradiation>
The superhydrophilic ability of the coating film obtained in Example 4 was evaluated under fluorescent lamp irradiation. The coating film after drying at room temperature was irradiated with black light for 12 hours to expose the titanium oxide surface. At this point, the contact angle is a superhydrophilic surface of 5 ° or less. After leaving this coating film in a dark place for 2 weeks, the contact angle was measured again and found to be about 28 °. The coating film with a contact angle of 28 ° was irradiated with a fluorescent lamp. It was confirmed that the contact angle decreased with the lapse of the irradiation time (FIG. 24). It returned to a complete superhydrophilic coating film again after 9 hours of irradiation with a fluorescent lamp. When this coating film was allowed to stand again in the dark for 8 hours and the contact angle was measured, it was confirmed that the superhydrophilic state was maintained. The above results show that the coating film of Example 4 exhibits a very high superhydrophilic function in the indoor space, which has extremely high practical performance (for example, for bathroom walls, toilets, etc.). I strongly suggest that

<Evaluation of antifouling function using methylene blue dye under fluorescent lamp irradiation>
The antifouling function of the coating film obtained in Example 4 was evaluated from the decolorization rate of a methylene blue dye generally used as a reagent for evaluating the photocatalytic antifouling function. First, the coating after drying at room temperature was irradiated with black light for 12 hours to expose the titanium oxide surface. Next, a drop of methylene blue aqueous solution was dropped, dried at room temperature, and evaluated for decolorization rate under fluorescent lamp irradiation. It can be confirmed that the decolorization of the methylene blue dye progresses as the fluorescent lamp irradiation time elapses (FIG. 25). Complete decolorization of the methylene blue dye was confirmed after 5 hours of irradiation. This indicates that the coating film of the present invention has not only a harmful gas decomposition performance under irradiation of a fluorescent lamp but also an extremely high anti-fouling function, and this has a high practical performance in an indoor space. I strongly suggest that

Example 5 and Comparative Example 3
Composition No. having a high resin solid content ratio in the composition. A coating film was produced on a glass substrate in the same manner as in Example 4 except that T12 was used (FIG. 26). FIG. 17 shows that the resin fills the space created by the powder (A1-1) in which the titanium oxide (a1-1) and the silica nanostructure (a2-1) are composited due to the high ratio of the resin. It can be confirmed by comparison with. However, the surface of the coating film has irregularities, and the presence of the powder (A1-1) can be confirmed on the outermost surface. For comparison, the composition No. obtained in Comparative Example 1 was used. A coating film was similarly produced using T32 (FIG. 27). Although the occurrence of cracks was suppressed due to the high presence ratio of the resin, it was confirmed that titanium oxide (a1-1) was buried in the resin and the catalyst could not be present on the coating film surface. .

<Coating evaluation 8: Photocatalytic activity under simulated sunlight irradiation>
The coating film obtained in Example 5 and Comparative Example 3 and the aqueous resin (B-1) were applied to a glass substrate in the same manner as in Example 3 and dried to simulate the photocatalytic activity of the coating film obtained. Evaluation was performed under sunlight irradiation (FIG. 28). Even when the resin solid content ratio is increased, it can be confirmed that the photocatalytic activity is 6 times or more when converted to the actual unit amount of titanium oxide. This is because titanium oxide (a1-1) can be exposed on the coating film surface by complexing titanium oxide (a1-1) with silica nanofibers in silica nanostructure (a2-1). It shows that.

Example 6 <Formation of a photocatalytic coating film by application of a one-component coating composition on a glass substrate: medium isopropanol>
Composition No. obtained in Example 3 A coating film was produced on a glass substrate in the same manner as in Example 4 except that T24 was used. The produced coating film was allowed to stand at room temperature for about one night and dried, and then irradiated with black light for 5 hours to obtain a photocatalytic coating film. The SEM observation image of this photocatalyst coating film was shown in FIG. Similar to the coating film obtained in Example 4, the surface is uneven, and it is possible to confirm the cranulated titanium oxide (a1-1) nanoparticles on the silica nanofiber surface observed on the outermost surface. it can.

<Coating evaluation 9: Photocatalytic activity under simulated sunlight irradiation>
The coating film obtained in Example 6 and Comparative Example 2 and the aqueous resin (B-1) were applied to a glass substrate as it was in Example 4 and dried to simulate the photocatalytic activity of the coating film obtained. Evaluation was performed under sunlight irradiation (FIG. 30). Even when the dispersion solvent was changed from distilled water to isopropanol, it was confirmed that the catalytic activity per unit amount of titanium oxide was 6 times or more. This suggests that the coating composition of the present invention can produce a good photocatalytic coating film even when alcohols are used as a medium.

Example 7 <Photocatalytic coating film having super hydrophilicity produced on a tile plate>
No. 2 obtained in Example 2. The coating composition of T14 was applied onto a commonly used ceramic tile using a commercially available brush and dried and cured overnight at room temperature. Before applying light to the cured coating film, the water contact angle was measured and found to be 108.3 ° (FIG. 31: c1). It was 5 degrees or less when the water contact angle was measured again after exposing it under sunlight for 1 hour outdoors (FIG. 31: c2). Before exposure, the surface of the photocatalytically active site was covered with resin, and the surface was formed by a hydrophobic component, so the water contact angle is considered to be high. Exposure to sunlight breaks down the resin component that covered the photocatalytically active site, its surface layer changes to the cueing state of the photocatalytically active site, and the uneven coating surface becomes a completely superhydrophilic film. It was. When the coating film was exposed outdoors for three months, there was no damage or damage to the coating film surface, and the superhydrophilicity with a water contact angle of 5 ° or less remained (FIG. 31: c3).

Example 8 <Photocatalytic coating film and photocatalytic activity formed on various substrates>
No. 2 obtained in Example 2. A coating film was prepared on various substrates other than the glass substrate using the coating composition of T14, and the photocatalytic activity was evaluated. The base materials used are wood (cypress), vinyl chloride plate, polyethylene terephthalate film (PET), acrylic plate, polycarbonate plate (PC), polystyrene plate (PS), stainless steel plate, aluminum plate, inner wall tile, outdoor tile, It is a tile for bath, natural stone, and cloth (cotton). In addition, about a vinyl chloride board, a polyethylene terephthalate film, an acrylic board, a polycarbonate board, a polystyrene board, a stainless steel board, and an aluminum board, plasma processing (Kasuga Denki Co., Ltd. plasma shower PS-601S) is performed for several seconds before application | coating, and the surface Was processed to a hydrophilic state. No. on each substrate. After the coating composition of T14 was applied, black light irradiation was performed for 12 hours to expose the titanium oxide surface. Each photocatalytic coating film after irradiation with black light exhibited a superhydrophilic function of 5 ° or less on all the substrates (see Tables 4 to 5). Also in the photodecomposition reaction of acetaldehyde gas under simulated sunlight irradiation, the photocatalytic activity was extremely high as in the coating film on the glass substrate (FIG. 32). This indicates that by using the one-component coating composition of the present invention, it is possible to easily form a photocatalytic coating on various substrates, and has extremely high practical performance in real space. I strongly suggest that

Example 9 <Production of coating film using composition after standing at room temperature for 3 months>
Composition No. obtained in Example 2 T14 was allowed to stand at room temperature of 25 ° C to 30 ° C for 3 months. The composition after standing for 3 months had a solid content, but could be redispersed by manual stirring. Using the composition after redispersion, a coating film was produced on a glass substrate in the same manner as in Example 4. After drying at room temperature for 1 day, it is possible to expose the nanoparticles of titanium oxide (a1-1) by irradiating with black light for 12 hours and confirming that the contact angle is 0.0. It was confirmed.

<Coating evaluation 10: Photocatalytic activity under simulated sunlight irradiation>
The photocatalytic activity of the coating films obtained in Example 4 and Example 9 was evaluated under simulated sunlight irradiation (FIG. 33). Even after the adjusted one-component coating composition is allowed to stand at room temperature for 3 months, the photocatalytic activity of the resulting coating film is good, and it is a photocatalytic coating film that is comparable to that applied immediately after adjustment. I confirmed that there was.

Example 10 <Immobilization of Tungsten Oxide (a3-1) to Silica Nanostructure (a2-2)>
The silica nanostructure (a2-2) obtained in Synthesis Example 1 and the tungsten oxide (a3-1) obtained in Synthesis Example 4 were used so that their use ratios were values shown in Table 6. A total of 1.5 g of the mixture was suspended in 30 ml of distilled water, subjected to ultrasonic irradiation for 1 hour, and then allowed to stand overnight. Distilled water was removed using a centrifuge and further dried using a vacuum dryer. The obtained powder was heated from room temperature to 300 ° C. for 30 minutes in an air atmosphere using an electric furnace, held at 300 ° C./1 hour, then raised to 400 ° C. over 30 minutes, and held at that temperature for 30 minutes. And then cooled naturally. With this firing program, the particles of tungsten oxide (a3-1) were baked and fixed on the silica nanostructure (a2-2). Table 6 shows the content of tungsten oxide in the obtained powder.

  Using TEM, sample no. As a result of T43 surface observation, it was confirmed that the tungsten oxide particles were fixed on the silica nanofibers (FIG. 34).

Example 11 <Immobilization of Tungsten Oxide (a3-1) to Silica Nanostructure (a2-4)>
As the silica nanostructure to be used, the silica nanostructure (a2-4) obtained in Synthesis Example 2 was used instead of the structure (a2-2) obtained in Synthesis Example 1 in the same manner as in Example 10. The tungsten oxide (a3-1) was fixed to the silica nanostructure by baking. Table 7 shows the proportions of tungsten oxide (a3-1) and silica nanostructure (a2-4) used, and the tungsten oxide content in the obtained solid.

  Using TEM, sample no. As a result of surface observation of T53, it was confirmed that the tungsten oxide particles were fixed on the silica nanosheet (FIG. 35).

Example 12 <Immobilization of Tungsten Oxide (a3-1) to Silica Nanostructure (a2-7)>
The silica nanostructure used is the same as in Example 10 except that the silica nanostructure (a2-7) obtained in Synthesis Example 3 is used instead of the structure (a2-2) obtained in Synthesis Example 1. The tungsten oxide (a3-1) was fixed to the silica nanostructure by baking. Table 8 shows the use ratio of tungsten oxide (a3-1) and silica nanostructure (a2-7), and the tungsten oxide content in the obtained solid.

  Using TEM, sample no. As a result of the surface observation of T63, it was confirmed that the tungsten oxide particles were fixed on the silica nanotubes (FIG. 36).

Example 13 <Adsorption of Tungsten Oxide (a3-1) to Silica Nanostructure (a2-1) and Immobilization by Firing>
Instead of the structure (a2-2) obtained in Synthesis Example 1, Example 10 is used except that the silica nanostructure (a2-1), which is a composite of the polymer obtained in Synthesis Example 1 and silica, is used. Similarly, tungsten oxide (a3-1) was adsorbed onto the silica nanostructure and fixed by baking (simultaneous removal of the polymer). Table 9 shows the proportion of tungsten oxide (a3-1), silica nanostructure (a2-1), which is a composite of polymer and silica, and the content of tungsten oxide in the obtained solid.

  Using TEM, sample no. As a result of surface observation of T73, it was confirmed that the tungsten oxide particles were fixed on the silica nanofibers (FIG. 37).

Example 14 <Immobilization to Silica Nanostructure (a2-7) Using Tungstate>
0.2 g of the silica nanostructure (a2-7) obtained in Synthesis Example 3 was weighed. Moreover, the ammonium metatungstate aqueous solution was adjusted to 5% using distilled water. The adjusted 5% aqueous solution is referred to as (a3′-1). These were mixed so as to have a mass ratio described in Table 10, and distilled water was further added to adjust the total volume to 10 ml. This was stirred for 1 hour, distilled water was removed from the resulting suspension, and further dried at 120 ° C. for 12 hours using a vacuum dryer. The dried powder was heated in an air atmosphere from room temperature to 300 ° C. using an electric furnace for 30 minutes, held at 300 ° C./1 hour, then raised to 600 ° C. over 30 minutes, and held at that temperature for 30 minutes. After that, it was naturally cooled. By this firing program, the tungsten oxide particles were baked and fixed on the silica nanostructure (a2-7). Table 10 shows the content of tungsten oxide in the obtained solid.

  Using TEM, sample no. Surface observation of T83 was performed, and it was confirmed that the tungsten oxide particles were fixed in the silica nanotubes in nano size (FIG. 38). In addition, the sample No. was measured using X-ray diffraction measurement. The crystal structure of T83 was examined and confirmed to be a tungsten oxide crystal structure (FIG. 39). In addition, the sample no. The absorbance spectrum of T83 was measured and confirmed to have an absorption region derived from tungsten oxide in the visible light region up to about 520 nm (FIG. 40).

Example 15 <Immobilization of Tungsten Oxide Nanoparticles to Silica Nanostructure (a2-7) Using Linear Polyethyleneimine>
After 0.7 g of the silica nanostructure (a2-7) obtained in Synthesis Example 3 was dispersed in 10 mL of distilled water, linear polyethyleneimine (PEI) powder obtained in Synthesis Example 1 was added, and 80 The polymer was dissolved by stirring at 0 ° C. for 1 hour. Then, standing cooling was performed for 30 minutes at room temperature. To this, 0.6 mL of an aqueous ammonium metatungstate solution was added so that the mass ratio of the silica nanostructure (a2-7) to the baked tungsten oxide was 70/30, and the mixture was stirred at room temperature for 1 hour. The supernatant distilled water was removed with a centrifuge, and then dried at 120 ° C. for 12 hours using a vacuum dryer to obtain a powder. In addition, the usage-amount of PEI measured and used so that it might become the ratio of Table 11 by molar ratio with an ethyleneimine unit with respect to ammonium metatungstate.

  The obtained powder was heated from room temperature to 300 ° C. in an air atmosphere for 30 minutes using an electric furnace, held at 300 ° C./1 hour, then raised to 600 ° C. over 30 minutes, and held at that temperature for 30 minutes. And then cooled naturally. With this firing program, the linear polyethyleneimine is removed, and the tungsten oxide particles are baked and fixed on the silica nanostructure (a2-7). The results are shown in Table 11.

  Using TEM, sample no. Surface observation of T93 was performed, and it was confirmed that the tungsten oxide particles were fixed on the silica nanotube in a nano size (FIG. 41). In addition, the sample No. The crystal structure of T93 was investigated and confirmed to be a tungsten oxide crystal structure (FIG. 42). In addition, the sample no. The absorbance spectrum of T93 was measured and confirmed to have an absorption region derived from tungsten oxide in the visible light region up to about 520 nm (FIG. 43).

Example 16 <Immobilization of Tungsten Oxide Nanoparticles Using Silica Nanostructure (a2-6) which is a Composite of Polymer and Silica>
An aqueous solution of ammonium metatungstate adjusted to 5% after 0.2 g of nanotube-like silica nanostructure (a2-6), which is a composite of the polymer and silica obtained in Synthesis Example 3, was dispersed in 10 mL of distilled water. (A3′-1) was weighed so as to have the mass ratio shown in Table 12, and after mixing, stirred at room temperature for 1 hour. The supernatant of the obtained suspension was removed using a centrifuge and the operation of washing with distilled water was repeated three times. The obtained precipitate was dried at 120 ° C. for 12 hours using a vacuum dryer to obtain a powder. The obtained powder was heated from room temperature to 300 ° C. in an air atmosphere for 30 minutes using an electric furnace, held at 300 ° C./1 hour, then raised to 600 ° C. over 30 minutes, and held at that temperature for 30 minutes. And then cooled naturally. By this firing program, the polymer component in the silica nanostructure (a2-6) disappears, and the tungsten oxide nanoparticles are baked and fixed on the silica nanostructure (a2-7). The results are shown in Table 12.

  Using TEM, sample no. The surface of T103 was observed, and it was confirmed that the tungsten oxide particles were fixed on the silica nanotubes in nano size (FIG. 44). In addition, the sample No. The crystal structure of T103 was investigated and confirmed to be a tungsten oxide crystal structure (FIG. 45). In addition, the sample no. The absorbance spectrum of T73 was measured and confirmed to have an absorption region derived from tungsten oxide in the visible light region up to about 520 nm (FIG. 46).

Comparative Example 3 <Fixation of tungsten oxide (a3-1) to silica gel>
Tungsten oxide (a3-1) was baked in the same manner as in Example 10 except that commercially available silica gel (Merck: silica gel 60, hereinafter referred to as B ′) was used as the silica material. The results are shown in Table 13.

Comparative Example 4 <Copper Divalent Salt Supported Tungsten Trioxide Visible Light Responsive Photocatalyst>
In order to evaluate the photocatalytic activity under LED irradiation, a copper divalent salt-supported tungsten trioxide visible light responsive photocatalyst was prepared as a comparative example (Trace experiment of JP 2009-226299 A).

Tungsten oxide powder (average particle size 250 nm, high purity chemical research inc.) Is passed through a filter to remove particles having a particle size of 1 μm or more, and pretreatment is performed by baking at 650 ° C. for 3 hours. Obtained. Then, the tungsten trioxide fine particles are suspended in distilled water so as to be 10% by mass, and then CuCl ₂ .2H ₂ O is added in an amount of 0.1% by mass (Cu (II) vs. WO ₃ ). (Wako Pure Chemical Industries, Ltd.) was added and heated to 90 ° C. with stirring for 1 hour. Next, after the obtained suspension is filtered by suction filtration, the residue is washed with distilled water, and further dried by heating at 110 ° C., so that tungsten trioxide fine particles supporting a copper divalent salt are used for comparison. Obtained as a sample.

Evaluation 1
<Evaluation of photocatalytic activity of tungsten oxide (a3-1)>
Using the tungsten oxide nanoparticles (a3-1) prepared using the linear polyethyleneimine obtained in Synthesis Example 4 and the tungsten oxide particles (α-1) obtained in Synthesis Example 5, An oxidative decomposition experiment was conducted to evaluate the catalytic activity as a photocatalyst. The results are shown in FIG. The tungsten oxide particles (α-1) show only about one third of the catalytic activity as compared with the tungsten oxide nanoparticles (a3-1). This is presumably because nanosized particles having a high specific surface area are formed by producing tungsten oxide particles using linear polyethyleneimine.

Evaluation 2
<Photocatalytic activity evaluation 1 of silica nanostructures with tungsten oxide particles fixed>
Sample No. of Example 10 T43, sample No. T53, sample no. The photocatalytic activity was evaluated using T63. As a comparison, sample No. The copper divalent salt-supported tungsten trioxide obtained in T113 and Comparative Example 4 was used. The results are shown in FIG. The light quantity of the LED lamp here was set to 20000 lx. In all samples of the present invention, extremely high acetaldehyde photolytic activity was confirmed. In particular, Sample No. No. 5 was baked and fixed on silica nanotubes. The catalytic activity of T63 was high, and the decomposition reaction of acetaldehyde tended to be almost completed after 20 minutes of light irradiation. Sample No. T63 was particularly excellent in initial activity, and the amount of carbon dioxide gas generated per unit time of light irradiation for 10 minutes was about 40 times that of the catalyst of Comparative Example 4. No. T63 is composed of about 35% tungsten oxide, and it can be confirmed that the catalyst functions efficiently. Sample No. obtained in Comparative Example 3 Even at T113, although the catalyst activity slightly exceeded that of the catalyst of Comparative Example 4, the activity was lower than that of the photocatalyst of the present invention.

Evaluation 3
<Comparison of photocatalytic activity before and after firing>
In Example 12, sample no. The photocatalytic activity before and after the firing of T63 was compared. The results are shown in FIG. It was confirmed that the catalytic activity was improved by baking and fixing tungsten oxide by the baking treatment. From this, it can be estimated that the interface between the tungsten oxide nanoparticles and the silica nanostructure is involved in the photocatalytic function.

Evaluation 4
<Photocatalytic activity evaluation 2 of silica nanostructures with fixed tungsten oxide particles>
Sample No. obtained in Example 13 The photocatalytic activity of T71 was evaluated. For comparison, the photocatalyst of Comparative Example 4 was used. The results are shown in FIG. Sample No. The amount of carbon dioxide gas generated per unit time of light irradiation by T71 was 28 times that of the comparative catalyst.

Evaluation 5
<Photocatalytic activity evaluation 3 of silica nanostructures with fixed tungsten oxide particles>
Sample No. obtained in Example 14 The photocatalytic activity of T83 was evaluated. For comparison, the photocatalyst of Comparative Example 4 was used. The results are shown in FIG. Sample No. The amount of carbon dioxide gas generated per unit time of light irradiation by T83 was 30 times that of the comparative catalyst.

Evaluation 6
<Evaluation of photocatalytic activity of silica nanostructures with fixed tungsten oxide particles 4>
Sample No. obtained in Example 15 The photocatalytic activity of T93 was evaluated. For comparison, the photocatalyst of Comparative Example 4 was used. The results are shown in FIG. Sample No. The amount of carbon dioxide gas generated per unit time of light irradiation by T93 was 28 times that of the comparative catalyst.

Evaluation 7
<Photocatalytic activity evaluation of silica nanostructures with fixed tungsten oxide particles 5>
Sample No. obtained in Example 16 The photocatalytic activity of T103 was evaluated. For comparison, the photocatalyst of Comparative Example 4 was used. The results are shown in FIG. Sample No. The amount of carbon dioxide gas generated per unit time of light irradiation by T103 was 29 times that of the comparative catalyst.

Evaluation 8
<Photocatalytic activity evaluation of silica nanostructures with fixed tungsten oxide particles under 5000 lx irradiation>
Sample No. obtained in Example 10 Using T43, the amount of LED irradiation was weakened to 5000 lx, and photolysis of acetaldehyde was performed under the conditions. For comparison, the photocatalyst of Comparative Example 4 was used. The results are shown in FIG. No. in the present invention. T43 showed remarkable catalytic activity from the beginning of irradiation, and the amount of carbon dioxide gas generated at 60 minutes after irradiation was 12 times that of the comparative catalyst.

Evaluation 9
<Evaluation of catalytic activity of silica nanostructures with fixed tungsten oxide particles under 550 lx irradiation>
In Evaluation 8, evaluation was performed in the same manner as in Evaluation 8 except that the amount of light to be irradiated was changed to 550 lx. The results are shown in FIG. In spite of such a weak amount of irradiation, the sample No. In T43, the amount of carbon dioxide generated significantly increased with the irradiation time, and the amount of carbon dioxide generated by irradiation after 60 minutes increased to 165 ppm. In the case of the catalyst used for comparison, the generation of clear carbon dioxide could not be confirmed even after 180 minutes of irradiation under irradiation with low light.

Example 17 <Preparation of one-component coating composition: medium 2-propanol>
0.375 g of the powder (A1-1) obtained in Example 1 and the sample No. obtained in Example 12 were used. 1.125 g [25/75 (mass ratio)] of T63 was suspended in 30 mL of 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd., for organic synthesis), and a mixer-type disperser film mix (PRIMIX 40-40 type) For 30 seconds at a rotational speed of 40 m / s. By carrying out dispersion treatment using this high-speed mixer, powder (A1-1) and No. T63 can be uniformly dispersed at the nano level. The resin (B-2) obtained in Synthesis Example 6 was diluted with 2-propanol so that the resin solid content was 55%. Powder (A1-1) and Sample No. The total mass (A) of T63 and the solid content mass ratio [(A1) + (A2)] / (B) of the binder resin (B) are mixed at the ratio shown in Table 1, and ultrasonic irradiation is performed for 1 hour. And a one-component coating composition was obtained.

Example 18 <Formation of a photocatalytic coating film by application of a one-component coating composition on a glass substrate>
Composition No. obtained in Example 17 A one-component coating composition of T124 was applied onto a glass substrate using an applicator (manufactured by YOSHIMITU) at a speed of 10 and an RDS16 bar coater. The produced coating film was allowed to stand and dry overnight at room temperature (25 ° C.) to obtain a photocatalyst coating film. The SEM observation image of this coating film was shown in FIG. The image that the surface uneven structure derived from the shape of the silica nanostructure spreads over the entire film can be confirmed.

Example 19 <Preparation of mixture of powder (A1-1) and resin (B-2) which is a composite photocatalyst of silica nanostructure and titanium oxide: medium 2-propanol>
Except using only powder (A1-1), it was made to disperse | distribute to 2-propanol like Example 17, Then, resin solid content was 55% using powder (A1-1) and 2-propanol. So that the solid mass ratio (A1) / (B) with the resin (B-2) diluted so as to become the ratio shown in Table 15 was subjected to ultrasonic irradiation for 1 hour, and the coating composition was Obtained.

Example 20 <Formation of Photocatalyst Coating Film by Application of Coating Composition Containing Only Powder (A1-1) on Glass Substrate>
No. obtained in Example 19 Except using the coating composition of T134, it apply | coated on the glass base material using the bar-coater like Example 18. FIG. The SEM observation image of this photocatalyst coating film was shown in FIG.

Example 21 <Preparation of mixture of powder (A2) and resin (B-2), which is a composite photocatalyst of silica nanostructure and tungsten oxide: medium 2-propanol>
Sample No. obtained in Example 12 Sample No. 1 was dispersed in 2-propanol in the same manner as in Example 17 except that only T63 was used. Mixing was performed so that the solid mass ratio (A2) / (B) of T63 and the resin (B-2) was the ratio shown in Table 3, and ultrasonic irradiation was performed for 1 hour to obtain a coating composition.

Example 22 <Formation of Photocatalyst Coating Film by Application of Coating Composition Containing Only Powder (A2) on Glass Substrate>
No. obtained in Example 21. Except using the coating composition of T144, it apply | coated on the glass base material using the bar coater like Example 18. FIG. The SEM observation image of this photocatalyst coating film was shown in FIG.

<Coating evaluation 11: Photocatalytic coating film No. under exposure to sunlight T14 Superhydrophilic Performance Evaluation>
The coating film obtained in Example 18, the coating film obtained in Example 20, and the coating film obtained in Example 22 were exposed to sunlight, and changes in the water contact angle with the passage of exposure days were evaluated ( FIG. 59). A clear decrease in water contact angle can be confirmed with the passage of exposure days, and all coating films become superhydrophilic coatings with a contact angle of 5 ° or less after 30 days of sunlight exposure. I confirmed. Although the coating film containing only the powder (A2) in which the silica nanostructure and the tungsten oxide are combined is superhydrophilic, it is superhydrophilic as compared with the powder (A1). Long-term exposure to sunlight is required. When only the composite type powder (A1) containing titanium oxide is used, the film is superhydrophilic in the shortest sunlight exposure time. This is because the powder (A1) in which the titanium oxide particles and the silica nanostructure are combined exhibits high photocatalytic activity in the coating film when exposed to sunlight, and the silica nanostructure forming the surface uneven structure is coated. It can be inferred that the titanium oxide nanoparticles came out in a short day of sunlight exposure by decomposing the binder resin component. In addition, the coating film in which both the powder (A1) and the powder (A2) are mixed is inferior to the coating film using only the powder (A1), but the coating film using only the powder (A2). Compared with, superhydrophilicity can be confirmed in a short exposure period. This is because the powder (A1) uniformly dispersed at the nano level exhibits extremely high photocatalytic activity under sunlight irradiation, so that not only the resin component present around the powder (A1) but also the powder (A2) It can be inferred that this is because the resin component present in the periphery of the resin was also decomposed to expose the tungsten oxide particle surface, which is a catalytically active site in the powder (A2), on the coating film surface. This is because the powder (A1) which is a composite of silica nanostructure and titanium oxide and the powder (A2) which is a composite of silica nanostructure and tungsten oxide are mixed to produce a coating film, which is highly visible. It suggests that the photocatalytic tungsten oxide photocatalytic active surface can be efficiently exposed under short-time light irradiation.

<Coating evaluation 12: Photocatalytic activity under LED illumination>
After exposure to sunlight until superhydrophilicity could be confirmed in coating film evaluation 11, photocatalytic activity evaluation was performed under LED illumination (coating film obtained in Example 18: 22 days, obtained in Example 20) Coating film: 10 days, coating film obtained in Example 22: Evaluation was performed after exposure to sunlight for 30 days). By LED illumination irradiation, clear decomposition of acetaldehyde can be confirmed from the coating film obtained in Example 18 and the coating film obtained in Example 22 (FIG. 60). On the other hand, the coating film using the powder (A1) containing only titanium oxide as an active site (the coating film obtained in Example 20) does not exhibit photocatalytic activity under LED illumination. The coating film obtained in Example 18 and the coating film obtained in Example 22 exhibit the same high LED response capability as the powder (A2) containing tungsten oxide as an active site works efficiently. ing. This means that by mixing the powder (A1) and the powder (A2) to produce a coating film, the tungsten oxide surface, which is a catalytically active site in the powder (A2), is clearly on the coating film surface. It suggests that it is exposed and functions as a photocatalytic coating film having high activity under the illumination of LED light, and mixing of the powder (A1) causes the exposure of the tungsten oxide active surface of the powder (A2) for a short period of time. It means that it is possible by light irradiation. From the above results, it is strongly suggested that the photocatalyst coating film of the present invention, particularly using tungsten oxide, has high practicality even under indoor LED illumination irradiation in real space.

Claims (11)

(1-1) a step of associating a polymer having a linear polyethyleneimine skeleton in an aqueous medium;
(1-2) A step of obtaining a composite of the polymer aggregate and silica by adding an alkoxysilane to the polymer aggregate obtained in the step (1-1) in the presence of an aqueous medium;
(1-3) The composite obtained in step (1-2), or a dispersion of silica nanostructure (a2) obtained by firing the composite and removing the polymer in the composite, and titanium oxide (a1) Are mixed in an aqueous medium to adsorb the titanium oxide (a1) powder,
(1-4) The composite or silica nanostructure (a2) adsorbing the titanium oxide (a1) powder obtained in the step (1-3) is baked at 600 to 900 ° C. to obtain the silica nanostructure (a2). Fixing titanium oxide (a1) of
In a water-based medium, a powder (A1) produced by passing titanium oxide (a1) and / or (2-1) a polymer having a linear polyethyleneimine skeleton, prepared by passing through a silica nanostructure (a2) The process of meeting at
(2-2) A step of obtaining a composite of the polymer and silica by adding an alkoxysilane to the polymer aggregate obtained in the step (2-1) in the presence of an aqueous medium;
(2-3) Tungstic acid in the dispersion of the composite obtained in step (2-2) or the dispersion of silica nanostructure (a2) from which the composite was baked to remove the polymer in the composite Mixing the salt (a3 ′) and adsorbing the tungstate (a3 ′) in the composite or silica nanostructure (a2);
(2-4) The composite or silica nanostructure (a2) having the tungstate (a3 ′) obtained in the step (2-3) is baked at 900 ° C. or less, and the silica nanostructure (a2) is obtained. Fixing tungsten oxide (a3) particles;
The powder (A2-1) produced by fixing tungsten oxide (a3) to the silica nanostructure (a2),
(3-1) A step of associating a polymer having a linear polyethyleneimine skeleton in an aqueous medium,
(3-2) a step of obtaining a composite of the polymer and silica by adding an alkoxysilane to the polymer aggregate obtained in the step (3-1) in the presence of an aqueous medium;
(3-3) A dispersion of the composite obtained in step (3-2), or a dispersion of the silica nanostructure (a2) obtained by firing the composite and removing the polymer in the composite ,
Mix polyamines,
A step of adsorbing a polyamine on the surface layer of the composite obtained in the step (3-2) or the silica nanostructure (a2);
(3-4) The tungstate (a3 ′) is mixed with the dispersion of the composite or silica nanostructure (a2) on which the polyamine obtained in the step (3-3) is adsorbed, and the composite or Adsorbing tungstate (a3 ′) in silica nanostructure (a2),
(3-5) The composite or silica nanostructure (a2) having the tungstate (a3 ′) obtained in the step (3-4) is baked at 900 ° C. or less, and the silica nanostructure (a2) is obtained. Fixing tungsten oxide (a3) particles;
Or (4-1) a polymer having a linear polyethyleneimine skeleton in which the tungsten oxide (a3) is fixed to the silica nanostructure (a2), or (4-1) a polymer having a linear polyethyleneimine skeleton. The process of meeting at
(4-2) A step of obtaining a composite of the polymer and silica by adding an alkoxysilane to the polymer aggregate obtained in the step (4-1) in the presence of an aqueous medium.
(4-3) A polymer having a linear polyethyleneimine skeleton is associated in an aqueous medium, and an aqueous solution of tungstate (a3 ′) is further mixed to form a polymer and tungstic acid or tungstate (a3 ′). A step of obtaining a precipitate formed by associating, and heating and firing this to obtain particles of tungsten oxide (a3);
(4-4) The tungsten oxide (a3) powder obtained in the step (4-3) and the polymer / silica composite obtained in the step (4-2), or the composite is fired, Silica nanostructure (a2) from which the polymer in the body has been removed is mixed in an aqueous medium, and particles of tungsten oxide (a3) are mixed.
A step of adsorbing to the composite of the polymer obtained in step (4-2) and silica, or silica nanostructure (a2);
(4-5) The composite or silica nanostructure (a2) adsorbed with the particles of tungsten oxide (a3) obtained in the step (4-4) is baked at 900 ° C. or lower to obtain the silica nanostructure (a2). Fixing tungsten oxide (a3) particles;
The tungsten oxide (a3), which is a powder (A2-3) produced through the process of fixing tungsten oxide (a3) to the silica nanostructure (a2), is fixed to the silica nanostructure (a2). A one-component coating composition comprising powder (A2) and a resin (B) having a polysiloxane skeleton. The one-component coating composition according to claim 1, wherein the titanium oxide (a1) or the tungsten oxide (a3) has a particle diameter in the range of 10 to 100 nm. The one-component type according to claim 1 or 2, wherein the silica nanostructure (a2) is a structure mainly composed of fiber-like or ribbon-like silica having a thickness or thickness of 10 to 100 nm and an aspect ratio of 2 or more. Paint composition. 2. The powder (A1) or (A2) is an aggregate of the silica nanostructures (a2), and the particle diameter of the powder (A1) or (A2) is in the range of 1 μm to 20 μm. The one-component coating composition according to any one of -3. 5. The one-component coating composition according to claim 1, wherein the content of titanium oxide (a1) in the powder (A1) is 10 to 80% by mass on a mass basis. 5. The one-component coating composition according to claim 1, wherein the content of tungsten oxide (a2) in the powder (A2) is 10 to 80% by mass on a mass basis. The resin (B) having a polysiloxane skeleton is formed by bonding a polymer having a polysiloxane skeleton to a side chain of a polymer of (meth) acrylate monomers. The one-component coating composition according to item 1. The use ratio of the total of the powder (A1) and the powder (A2) and the resin (B) is 10 in a mass ratio represented by [(A1) + (A2)] / (B). The one-component coating composition according to any one of claims 1 to 7, which is in the range of / 90 to 80/20. Applying and curing the one-component coating composition according to any one of claims 1 to 8 on a substrate;
A step of photodegrading the organic component of the coating layer by irradiating the coating obtained in the above step with light,
The manufacturing method of the coating film characterized by having. A photocatalytic coating film obtained by the production method according to claim 9. A superhydrophilic coating film obtained by the production method according to claim 9 .

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