JP2005261997A - Method for producing photocatalytic body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a photocatalytic body in which photocatalytic particles are firmly bonded onto a resin substrate without damaging the photocatalytic function of the particles and the particles are hardly separated from the substrate and the resin substrate is hardly deteriorated even when used for a long term. <P>SOLUTION: This method is provided for producing a fine particle-fixed body by bonding the photocatalytic fine particles onto the substrate according to chemical bonding of a silane coupling agent to the surface of the substrate, wherein a thin film of the silane coupling agent having unsaturated bonds is formed on the surface of the photocatalytic fine particle, the thin film formed on the surface of the photocatalytic fine particle is brought into contact with a resin surface of the resin substrate and the resin surface is chemically bonded to unsaturated bonds existing in the thin film. Here, it is preferable that graft polymerization is used for the chemical bonding and that radiation graft polymerization is used for the graft polymerization. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a photocatalyst by chemically bonding photocatalyst particles that induce various reactions such as deodorization, sterilization of microorganisms, and removal of low-concentration nitrogen oxides in the air.

  Photocatalyst particles exhibit various performances such as antifouling, antifogging, sterilization, deodorization, and air purification by the strong reducing power of electrons generated by photoexcitation and the strong oxidizing power of holes. Application development is progressing in various fields such as building materials and civil engineering. Recently, visible light responsive photocatalyst particles that respond to visible light have also been developed, and can be applied to indoor applications where the amount of ultraviolet rays is small. Therefore, in order to apply various effective functions of photocatalyst particles in various fields such as daily necessities, building materials, and civil engineering, photocatalyst particles can be firmly and without impairing the photocatalytic function on any substrate. Therefore, there is a demand for a method of bonding and bonding so that the photocatalytic function does not exert on the substrate to be bonded. In particular, when the substrate to which the photocatalyst particles are bonded is a resin, the photocatalyst function is deteriorated due to desorption of the bonded photocatalyst particles due to the strong oxidizing power of the photocatalyst particles, and the original function of the resin substrate is impaired. There was a problem. Therefore, when the photocatalyst particles are used by being bonded to the surface of a fiber, a film, or a molded body made of a resin, the photocatalyst particle bonding method in which the resin hardly deteriorates is an extremely important technique from the viewpoint of practicality. .

Conventionally, as a method for bonding photocatalyst particles to a resin substrate, a method using an organic binder such as a fluororesin, which is hardly deteriorated even by a strong oxidizing power of photocatalyst particles (see, for example, Patent Document 1), silicone. A method using an organic binder such as a resin (see, for example, Patent Document 2) has been proposed. In addition, a method for preventing contact between the base resin and the photocatalyst fine particles has also been proposed. For example, a method in which the surface of the photocatalyst fine particles is coated with an inorganic substance such as water glass or methyl silicate and fixed to the fiber surface with a binder resin (for example, Patent Documents). 3), and a method of forming an inorganic film such as silicon oxide or aluminum oxide on the resin surface by a sputtering method (see, for example, Patent Documents 4 and 5).
JP-A-10-216210 JP-A-10-001879 JP-A-11-269760 Japanese Patent Laid-Open No. 10-017614 JP 2002-248355 A

  When using the above-mentioned fluororesin as a binder, it is difficult to adhere to the resin substrate surface with tetrafluoroethylene having the most excellent oxidation resistance. Therefore, in order to improve the adhesion, a thermosetting resin is mixed and used. It has been. However, since a resin made of hydrocarbon is mixed in addition to the fluororesin, the resin made of hydrocarbon is decomposed by the strong oxidizing power of the photocatalyst particles, so that there is a problem that coloring, malodor, etc. occur. Further, in the case of a silicone resin, there are problems such that it is difficult to form a fixed layer of uniform photocatalyst particles and adhesion to a resin substrate depending on the type of silicone resin used.

  On the other hand, in order to prevent the contact between the photocatalyst particles and the resin substrate, a method of coating the surface of the photocatalyst fine particles with other inorganic substances has also been proposed, but there are problems such as a decrease in photocatalytic activity. A method of forming an inorganic coating such as dense silicon oxide or aluminum oxide with excellent barrier properties on the substrate surface has also been proposed, but depending on the difference in thermal expansion coefficient between the resin substrate and the inorganic coating and the type of resin It is difficult to form an inorganic film having excellent properties, and there are still various problems that need to be solved, such as deformation of the resin substrate due to heat generated by sputtering and low productivity.

  The present invention solves the above-mentioned problems of the prior art, is difficult to cause degradation by a photocatalyst of a substrate having at least a surface made of resin, such as fibers, films, cloths, etc., and deodorizing, sterilizing microorganisms, in the air An object is to provide a method for producing a photocatalyst suitable for various purposes such as removal of low-concentration nitrogen oxides.

  As a result of intensive studies, the present inventors have used a silane coupling agent having an unsaturated bond with excellent reactivity, and thus the photocatalyst fine particles are firmly adhered to the surface of the substrate without losing the photocatalytic activity as much as possible. In addition, the inventors have found a method for bonding the base resin so that the deterioration due to the photocatalyst fine particles hardly occurs, thereby obtaining knowledge that the activity of the combined photocatalyst fine particles can be maximized. Created a manufacturing method.

  That is, the first invention is a method for producing a photocatalyst having at least a substrate surface made of a resin, wherein a thin film of a silane coupling agent having an unsaturated bond is formed on the photocatalyst fine particles, and the resin on the substrate surface and the photocatalyst are formed. The present invention provides a method for producing a photocatalyst by contacting a thin film formed on the surface of fine particles and chemically bonding the resin surface and an unsaturated bond present on the thin film.

  The second invention is a method for producing a photocatalyst having at least a substrate surface made of a resin, wherein a thin film of a silane coupling agent having an unsaturated bond is formed on the inorganic fine particles, and the inorganic fine particles formed with the thin film Forming a coating thin film on the substrate surface, forming a thin film of a silane coupling agent having an unsaturated bond on the photocatalyst fine particles, contacting the coating thin film with the photocatalyst fine particles forming the thin film, The present invention provides a method for producing a photocatalyst by chemically bonding an unsaturated bond present in a coating thin film of inorganic fine particles and an unsaturated bond present in a thin film of photocatalytic fine particles.

  Furthermore, the present invention provides the photocatalyst according to the second invention method, wherein the coating thin film comprising the inorganic fine particles contains a silane coupling agent and / or a silane compound having an unsaturated bond. A method is provided.

  Furthermore, the third invention is a method for forming a coating thin film comprising a silane coupling agent having at least an unsaturated bond on a substrate surface (resin surface) by graft polymerization, and for producing a silane coupling agent having an unsaturated bond on a photocatalyst fine particle. A thin film is formed, and the surface of the coating thin film and the photocatalyst fine particles formed with the thin film are brought into contact with each other, and the coating thin film surface formed with the silane coupling agent and the unsaturated bond existing in the thin film of the photocatalytic fine particles are chemically The present invention provides a method for producing a photocatalyst that is bonded.

  Furthermore, the present invention provides the method for producing a photocatalyst according to the third invention method, wherein the coating thin film comprising the silane coupling agent having an unsaturated bond contains inorganic fine particles. Is.

  Furthermore, in the fourth invention, a coating thin film made of a silane coupling agent having at least an unsaturated bond is formed on the substrate surface (resin surface) by graft polymerization, and photocatalyst fine particles are brought into contact with the coating thin film to form a coating thin film. The present invention provides a method for producing a photocatalyst by combining an existing silanol group and a functional group present on the surface of a photocatalyst fine particle by a dehydration condensation reaction.

  Furthermore, the present invention provides a method for producing a photocatalyst according to any one of the first to third inventions, wherein the chemical bond is graft polymerization.

  Furthermore, the present invention provides a method for producing a photocatalyst, wherein radiation graft polymerization is used as graft polymerization in the third or fourth invention method.

  According to the present invention, there is provided a method for producing a photocatalyst body having at least a substrate surface made of a resin, wherein photocatalyst fine particles are immobilized on the surface of the substrate by chemical bonding via a silane coupling agent, A dense thin film of silicon oxide formed by condensation of silanol groups formed by hydrolysis of alkoxy groups or a dense thin film of inorganic fine particles is formed between the surface and the photocatalyst fine particles. Since the thin film of silicon oxide or inorganic fine particles prevents direct contact between the photocatalyst particles and the resin substrate, the resin substrate surface does not receive the strong oxidation and reduction action of the photocatalyst particles. It can be manufactured and provided.

  Therefore, according to the production method of the present invention, it is possible to provide a photocatalyst body excellent in durability in which the photocatalyst fine particles are firmly bonded to the surfaces of various resin substrates. In addition, since the photocatalyst fine particles are arranged on the surface of the base material without being covered with the binder, the activity of the photocatalyst fine particles is hardly impaired, and the photocatalyst fine particles are in an island shape, a single particle film shape or a multilayer particle film shape. Since it can be immobilized on a substrate made of fiber, film, cloth, etc., the texture of these substrates is not impaired, and therefore it is possible to provide a photocatalyst that can be applied in various fields.

  In the method of the present invention, the substrate can have various forms (shape, size, etc.) suitable for the purpose of use, such as film, fiber, cloth, mesh, and honeycomb. . Therefore, according to the production method of the present invention, it is possible to add the function of the photocatalyst fine particles to various bases of these various forms, building materials such as outer wall materials, sashes, doors, blinds, wallpaper, carpets, Interior materials such as resin tiles, clothing, innerwear, socks, gloves, shoes and other footwear, insoles for the footwear, pajamas, mats, sheets, pillows, pillowcases, blankets, towels, quilts and quilts It can be applied to products such as filters, insect nets, etc., such as accessories, hats, handkerchiefs, towels, carpets, curtains, air purifiers, air conditioners, ventilation fans, electric vacuum cleaners, and electric fans.

  The present invention is described in further detail below.

  The photocatalyst fine particles used in the present invention are particles that exhibit a photocatalytic function by irradiating light with a wavelength having energy equal to or greater than the band gap. Titanium oxide, zinc oxide, tungsten oxide, iron oxide, Known metal compound semiconductors such as strontium titanate, cadmium sulfide, and cadmium selenide can be used singly or in combination of two or more. Of these photocatalyst fine particles, titanium oxide that is excellent in transparency, durability, and harmless is preferably used.

The crystal structure of titanium oxide is not limited in the present invention even if it is a rutile type, an anadase type, a brookite type, or an amorphous type. Further, TiO _{2-x (X} which part of oxygen atoms deviates significantly from the TiO _2-x N _x or oxygen atom substituted with a nitrogen atom is missing stoichiometric ratio is the anion of titanium oxide 1.0 ) Etc. are also used.

  A metal or a metal compound such as vanadium, copper, nickel, cobalt, chromium, palladium, silver, platinum, or gold may be contained in the photocatalyst fine particles or the surface thereof for the purpose of increasing the photocatalytic function.

  Further, an adsorbent may be used together with the photocatalyst fine particles, and the deodorizing performance and the pollutant removal performance in the ambient air can be improved by using the photocatalyst fine particles and the adsorbent in combination. Suitable adsorbents include carbon-based adsorbents such as activated carbon, zeolite-based adsorbents, molecular sieves, apatite, alumina, silicon oxide and other metal oxide-based adsorbents, and chelate resins.

In addition to fine particles of photocatalyst, fine particles composed of one or more kinds of antibacterial materials selected from metals such as silver, copper, and zinc, and compounds thereof, dabitite, senurite, blannelite, nymphite, lincaite, Radioactive rare, such as carnotite, thamumite, metachamunite, francesville stone, toll stone, coffin stone, samarsky stone, thorium stone, tro rubber stone, samarsky stone, thorium stone, tro rubber stone, monazite, tantalum stone, badelite, ilmenite Natural radioactive rare element minerals containing trace amounts of elements, fine particles made of materials that generate negative ions such as fused zirconia obtained by refining some of these minerals, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Metal oxides such as SiO ₂ , Fe ₂ O ₃ , CoO, CuO, MgO and mixtures thereof For example, fine particles of materials emitting far infrared rays such as cordierite, β-spodumene, aluminum titanate, near infrared rays such as LaB ₆ , CeB ₆ , NdB ₆ , SnO ₂ , In ₂ O ₃ , ruthenium oxide, rhenium oxide A plurality of fine particles made of materials having various functions, such as fine particles made of a material that absorbs water, may be used.

  The diameter of the photocatalyst fine particles and the fine particle sizes of the other various materials are not particularly limited, but in order to suitably perform graft polymerization described later, the average particle size is preferably 500 nm or less. Furthermore, if the average particle size is 300 nm or less, a stronger bond to the substrate is achieved, which is more preferable from the viewpoint of durability.

  In the present invention, the photocatalyst fine particles are chemically bonded to the surface of the resin substrate, the surface of the coating thin film made of inorganic fine particles, or the surface of the coating thin film made of the silane coupling agent with a silane coupling agent having an unsaturated bond. It is to be fixed. Specific examples of the unsaturated bond of the silane coupling agent include a vinyl group, an epoxy group, a styryl group, a methacrylo group, an acryloxy group, and an isocyanate group. In the present invention, by using a silane coupling agent having excellent reactivity, the photocatalyst fine particles are converted into a chemical bond of the photocatalyst fine particles by a dehydration condensation reaction of silanol groups of the silane coupling agent and the functional group to the substrate resin surface. This is a method for producing a fine particle immobilization body bonded to the surface of a substrate through chemical bonding by graft polymerization or unsaturated bond present in a coating thin film formed of inorganic fine particles.

  Examples of the silane coupling agent used in the present invention include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, N- (Vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycyl Sidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldie G Shishiran, 3-methacryloxypropyl triethoxysilane, 3-acryloxy propyl trimethoxy silane, 3-isocyanate propyl triethoxysilane and the like.

  These silane coupling agents are used alone or in combination. As a form of use, a necessary amount of a silane coupling agent is dissolved in an organic solvent such as methanol, ethanol, acetone, toluene, xylene, and water necessary for hydrolysis is added as necessary. In addition, mineral acids such as hydrochloric acid and nitric acid are added to improve dispersibility. Solvents used include ethanol, methanol, lower alcohols such as propanol and butanol, lower alkyl carboxylic acids such as formic acid and propionic acid, aromatic compounds such as toluene and xylene, esters such as ethyl acetate and butyl acetate, methyl Cellosolves such as cellosolve and ethylcellosolve may be used alone or in combination. Furthermore, the silane coupling agent may be used in the state of an aqueous solution, and in the case where the solubility in water is poor, acetic acid is added to adjust the pH to weak acidity to promote the hydrolyzability of alkoxysilane, Used with increased water solubility.

  The photocatalyst fine particles used in the present invention are used for production in a state of being dispersed in the above-mentioned solution of the silane coupling agent. Dispersion of fine particles having various functions is performed by stirring and dispersing using a homomixer or a magnetic stirrer, pulverizing / dispersing using a ball mill, sand mill, high-speed rotating mill, jet mill, etc., or using ultrasonic waves. Is called.

  The photocatalyst fine particles are used in the production of a fine particle fixed body in the form of a dispersed colloidal dispersion or a dispersion obtained by pulverization. The photocatalyst fine particle dispersion is prepared by adding a silane coupling agent to a colloidal dispersion or a dispersion obtained by pulverization, and then bonding the silane coupling agent to the surface of the photocatalyst fine particles by a dehydration condensation reaction while heating under reflux. A thin film made of a silane coupling agent is formed. The amount of the silane coupling agent that is reactively bonded to the photocatalyst fine particles under reflux depends on the average particle diameter of the fine particles, but is 0.01% to 5.0% by weight with respect to the weight of the fine particles to be reactively bonded. There is no practical problem with the bonding strength of the fine particles. Moreover, there may be an excess silane coupling agent that is not deposited in the bond.

In particular, when the thin film made of photocatalyst fine particles becomes thick, the photocatalytic thin film may be deteriorated due to cohesive failure depending on the stress and use environment of the thin film. An alkoxysilane compound represented by Si (OR ₁ ) ₄ (wherein R ₁ represents an alkyl group having 1 to 4 carbon atoms), for example, tetramethoxysilane, tetraethoxysilane, etc., R _2n Si (OR ₃ ) _4-n (wherein R ₂ is a hydrocarbon group having 1 to 6 carbon atoms, R ₃ is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 3), Examples include methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexamethyldisilazane, hexyltrimethoxysilane, etc. Such as carboxymethyl oligomer used is added.

  Next, a detailed coating thin film made of inorganic fine particles and a dense coating thin film made of a silane coupling agent for inhibiting the influence of photocatalyst fine particles on the surface of the base resin by oxidation or reduction will be described in detail.

  The inorganic fine particles used in the present invention may be made of a material that is not affected by active species such as hydroxy radicals generated when light is irradiated to the photocatalyst fine particles. Specifically used materials include metal oxides such as silicon oxide, alumina oxide, zirconia oxide, indium oxide and tin oxide, nitrides such as titanium nitride, chromium nitride and tantalum nitride, silicon carbide, chromium carbide, tungsten carbide, etc. Inorganic compounds such as carbides of

  Further, materials having adsorptivity, carbon compounds such as activated carbon, fullerene and carbon nanotubes, activated alumina such as apatite and γ-alumina, silicon oxide, zeolite adsorbent, molecular sieve and the like are also used. Furthermore, the above-described materials that generate negative ions, materials that emit far-infrared rays, and materials that absorb near-infrared rays are also used in the form of fine particles. The fine particles made of these materials may be formed by a dehydration condensation reaction with the above-described thin film of a silane coupling agent having an unsaturated bond. Furthermore, when forming the coating thin film which consists of the said inorganic fine particle, the silane coupling agent which has an excess unsaturated bond may be contained.

  Furthermore, when forming the coating thin film which consists of the said inorganic fine particle, the silane coupling agent which has an excess unsaturated bond may be contained, and the silane compound may be contained in addition. Examples of the silane compound used include silane coupling agents having no unsaturated bond, such as vinyltrichlorosilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-amino. Examples include aminosilanes such as methylpropyldimethoxysilane, 3-chloropropyltrimethoxysilane, mercaptopropyldimethoxysilane, and bis (triethoxysilylpropyl) tetrasulfide.

Further, as other silane compounds, alkoxysilane compounds represented by Si (OR ₁ ) ₄ (wherein R ₁ represents an alkyl group having 1 to 4 carbon atoms), for example, tetramethoxysilane, tetraethoxysilane R _2n Si (OR ₃ ) _4-n (wherein R ₂ is a hydrocarbon group having 1 to 6 carbon atoms, R ₃ is an alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 3) As an example, methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexamethyldisilazane, hexyltrimethoxysilane, and further, an alkoxy oligomer, etc. Can be mentioned.

  Furthermore, the coating thin film made of a silane coupling agent is mainly composed of a silane coupling agent having an unsaturated bond, in addition to the above-mentioned fine particles made of an inorganic compound, a silane coupling agent not having an unsaturated bond, and the aforementioned An alkoxysilane compound and an alkoxy oligomer are included as necessary.

  A coating thin film made of a silane coupling agent is formed by hydrolyzing an alkoxy group contained in the silane coupling agent, and forming a dense silicon oxide thin film by combining silanol groups generated by hydrolysis through a dehydration condensation reaction. The formed dense silicon oxide thin film inhibits the contact of the active species such as hydroxy radicals generated by the photocatalyst with the base resin, so that the base resin is hardly deteriorated. Can be manufactured.

  The material constituting the substrate used in the production of the photocatalyst of the present invention may be any material that can be chemically bonded by a silane coupling agent having an unsaturated bond. Examples of such a material include various resins. And synthetic fibers and natural fibers. Moreover, the base | substrate used for manufacture of the photocatalyst body of this invention should just be that the surface consists of resin at least.

  Here, synthetic resin or natural resin is used as the resin constituting the surface or the whole of the substrate, and examples thereof include polyethylene resin, polypropylene resin, polystyrene resin, ABS resin, AS resin, EVA resin, and polymethylpentene. Resin, polyvinyl chloride resin, polyvinylidene chloride resin, polymethyl acrylate resin, polyvinyl acetate resin, polyamide resin, polyimide resin, polycarbonate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyacetal resin, polyarylate resin, polysulfone resin , Thermoplastic resins such as polyvinylidene fluoride resin and PTFE, polylactic acid resin, polyhydroxybutyrate resin, modified starch resin, polycaprolacto resin, polybutylene succinate resin, polybutylene adip Biodegradable resins such as terephthalate resin, polybutylene succinate terephthalate resin, polyethylene succinate resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, epoxy resin, epoxy acrylate resin, silicon resin, Thermosetting resins such as acrylic urethane resins and urethane resins, elastomers such as silicone resins, polystyrene elastomers, polyethylene elastomers, polypropylene elastomers and polyurethane elastomers, natural resins such as lacquer, and the like can be mentioned.

  In the method of the present invention, these resins can be applied in various shapes and sizes suitable for the purpose of use, such as plate, film, fiber, cloth, mesh, and honeycomb. Is not to be done. In addition, these resins are laminated in the form of a film on the surface of each material when the main part of the base is a metal material such as aluminum, magnesium, iron, or an inorganic material such as glass or ceramics. It may be formed as a thin film by a coating method such as spray coating, immersion coating or electrostatic coating, or a printing method such as screen printing or offset printing. Furthermore, these resins may be colored with pigments or dyes, or may be filled with inorganic materials such as silica, alumina, diatomaceous earth, mica and the like.

  The substrate may be a fiber made of synthetic resin (synthetic fiber, chemical fiber). Examples of the synthetic fiber constituting the substrate include polyester fiber, polyamide fiber, polyvinyl alcohol fiber, acrylic fiber, and vinyl chloride fiber. , Vinylidene chloride fiber, polyolefin fiber, polycarbonate fiber, fluorine fiber, polyurea fiber, elastomer fiber, and composite fiber of the material constituting these fibers and the resin material. In the method of the present invention, since the substrate surface may be a resin as described above, when a fiber other than a synthetic resin is used as the substrate material, the resin is applied to the fiber surface by the various coating methods described above. Thus, the resin may be formed as a thin film. Therefore, as examples of natural fibers, cotton, hemp, silk, Japanese paper obtained from natural fibers, and the like can be used as the base material.

  Furthermore, examples of the graft polymerization in the method of the present invention include graft polymerization using a peroxide catalyst, graft polymerization using heat and light energy, and graft polymerization by radiation. Among these, the simplicity of the polymerization process, production speed, etc. From the above viewpoint, radiation graft polymerization is particularly suitable. Here, examples of the radiation used in the graft polymerization include α rays, β rays, γ rays, electron rays, ultraviolet rays, and the like. In the present invention, γ rays, electron rays, and ultraviolet rays are particularly used. Are suitable.

  The method for producing a photocatalyst using graft polymerization in the present invention is preferably produced by the method described below. In a first preferred method of the first invention, a solution in which photocatalyst fine particles in which a thin film of an unsaturated bond-containing silane coupling agent is formed is applied to the surface of the substrate to be bonded, and if necessary After removing the solvent by a method such as heat drying, the substrate surface coated with the mixture of photocatalyst fine particles on which a thin film of the silane coupling agent is formed is irradiated with radiation such as γ rays, electron beams, or ultraviolet rays. Thus, the silane coupling agent is produced by so-called simultaneous irradiation graft polymerization, which is carried out by graft polymerization of the silane coupling agent onto the substrate surface and at the same time bonding the photocatalyst fine particles.

  In addition, as a second preferred method in the first invention, a silane coupling agent having an unsaturated bond after irradiating the surface of the substrate to which the photocatalyst fine particles are bound with a radiation such as γ-ray, electron beam or ultraviolet ray. It is produced by so-called pre-irradiation graft polymerization in which a solution in which the photocatalyst fine particles in which the thin film is formed is applied is applied, the silane coupling agent and the substrate are reacted and the photocatalyst fine particles are bonded at the same time.

  As a preferred method in the second invention, after forming a coating thin film composed of inorganic fine particles in which a thin film of a silane coupling agent having an unsaturated bond is formed on the substrate surface in advance, the solvent is removed by drying as necessary. Or by irradiating with radiation and bonding to the surface of the substrate through graft polymerization via a silane coupling agent, and then dispersing the solution in which the photocatalyst fine particles in which a thin film of a silane coupling agent having an unsaturated bond is formed are dispersed By forming the coating thin film surface made of inorganic fine particles and irradiating with radiation, the coating thin film formed on the inorganic fine particles reacts with the substrate and the silane coupling agent formed on the substrate and the photocatalyst fine particles. It is produced by a method of combining photocatalyst particles.

  As a preferred method in the third invention, a silane coupling agent is previously formed by graft polymerization of a silane coupling agent on the surface of a substrate in advance by a simultaneous irradiation method or pre-irradiation method of radiation such as γ rays, electron beams, and ultraviolet rays. After forming the coating film, a solution in which fine particles to which the silane coupling agent is bonded is dispersed is applied onto the coating film on the surface of the substrate, and then irradiated with radiation, whereby the fine particles are applied to the surface of the substrate by graft polymerization. Manufactured by a method of bonding. Even in this case, the silane coupling agent is applied to the surface of the substrate, and if necessary, a solution in which the fine particles with the silane coupling agent are dispersed is applied onto the coating film from which the solvent has been removed by a method such as heat drying. It is also possible to manufacture by a method in which fine particles are bonded to the substrate surface by graft polymerization by irradiating with radiation.

  As a preferred method in the fourth invention, a silane coupling agent having an unsaturated bond on the substrate surface (resin surface) in advance is grafted by a simultaneous irradiation method or a pre-irradiation method of radiation such as γ rays, electron beams or ultraviolet rays. After the polymerization, a solution in which the photocatalyst fine particles are dispersed is applied to the surface of the substrate on which the silane coupling agent is graft-polymerized, and then energy such as heating is applied to introduce the silanol groups and photocatalyst introduced onto the surface of the substrate by graft polymerization. It is produced by a method in which the photocatalyst fine particles are bonded to the substrate surface by a dehydration condensation reaction with hydroxyl groups present on the fine particle surfaces.

  In the present embodiment, as described above, the solution in which the photocatalyst fine particles to be immobilized are dispersed is applied to the surface of the substrate to be immobilized to produce a photocatalyst immobilized body. As a commonly performed spin coating method, dip coating method, spray coating method, cast coating method, bar coating method, micro gravure coating method, gravure coating method, or a method of partially coating, screen printing method, Various methods such as a pad printing method, an offset printing method, a dry offset printing method, a flexographic printing method, and an ink jet printing method are used, and there is no particular limitation as long as a coating suitable for the purpose can be performed.

  In addition, in order to carry out graft polymerization of the silane coupling agent efficiently and uniformly, the surface of the resin substrate is previously subjected to corona discharge treatment, plasma discharge treatment, flame treatment, oxidizing properties such as chromic acid and perchloric acid. Hydrophilic treatment may be performed by chemical treatment with an alkaline aqueous solution containing an acid aqueous solution or sodium hydroxide.

  According to the present invention, as described above, the photocatalyst fine particles can be fixed in various forms (shape, size, etc.) suitable for the purpose of use, such as film, fiber, cloth, mesh, and honeycomb. , Exterior wall materials, sashes, doors, blinds and other building materials, wallpaper, carpets, interior materials such as resin tiles, clothing, innerwear, socks, gloves, shoes and other footwear, insoles for such footwear, pajamas, mats Bedding, sheets, pillows, pillowcases, blankets, towels, quilts and quilt covers, hats, handkerchiefs, towels, carpets, curtains, air purifiers and air conditioners, ventilation fans, vacuum cleaners, fan filters or insect repellents Various functions can be added to the network. Therefore, the present invention is a useful method capable of providing various products excellent in various fields.

  In addition, according to the present invention, since the photocatalyst fine particles can be firmly fixed on the substrate by chemical bonding, the photocatalyst fine particles can be formed after being spun into a product shape or in the process of commercialization. There is an advantage that the presence of fine particles does not affect the spinnability.

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.

<Production of photocatalyst>
In the production of the photocatalysts of the following Examples 1 to 15 according to the method of the present invention, an electrocurtain type electron beam irradiation device, CB250 / 15 / 180L, manufactured by Iwasaki Electric Co., Ltd. was used, and the photocatalyst body was subjected to electron beam graft polymerization. . On the other hand, in the production of the photocatalyst of each comparative example, an electron beam was not used, and a post-application heating and drying method was used.

Example 1:
Commercially available photocatalyst fine particles (BA-PW25, manufactured by Eco Device Co., Ltd.) were dispersed in methanol by 5.0% by weight and adjusted to pH 1.5 with hydrochloric acid, and then pulverized and dispersed with a bead mill to an average particle size of 18 nm. After adding 1.0% by weight of 3-methacryloxypropyltrimethoxysilane having an unsaturated bond to the photocatalyst fine particle pulverized dispersion solution to the photocatalyst fine particles, the pulverized dispersion solution is added to a flask equipped with a cooling tube. Then, the flask was heated in an oil bath and treated under reflux for 4 hours to bond the silane coupling agent to the surface of the photocatalyst fine particles by a dehydration condensation reaction to form a thin film. The average particle diameter of the photocatalyst fine particles in the obtained photocatalyst fine particle dispersion was 14 nm.

  Further, the photocatalyst fine particle dispersion was applied to the surface of a 125 μm polyester film (Plumac Corp., Lumirror) with a bar coater and dried at 120 ° C. for 3 minutes. Next, the polyester film coated with the photocatalyst fine particle dispersion was irradiated with an electron beam at an acceleration voltage of 200 kV for 5 Mrad to obtain a photocatalyst in which the photocatalyst fine particles were bonded to the surface of the polyester film by graft polymerization of a silane coupling agent. .

Example 2:
The polyester film used for the substrate in Example 1 was irradiated with an electron beam at an acceleration voltage of 200 kV for 10 Mrad, and then the polyester film irradiated with the electron beam was immersed in the photocatalyst fine particle dispersion prepared in Example 1 to irradiate the electron beam. The photocatalyst particles were bonded by graft polymerization of the silane coupling agent to the polyester film surface by radicals generated on the surface and inside of the film, and then the excess dispersion was removed by washing to obtain a photocatalyst.

Example 3:
A 5.0 wt% isopropyl alcohol solution of 3-glycidoxypropyltriethoxysilane having an unsaturated bond was applied to the surface of the polyester film used in Example 1 by a bar coater. After drying at 120 ° C. for 5 minutes, an electron beam was irradiated at an acceleration voltage of 200 kV for 3 Mrad to form a coating thin film in which the silane coupling agent was bonded to the polyester film surface by graft polymerization. Next, the photocatalyst fine particle dispersion solution used in Example 1 was applied to the coating thin film surface with a bar coater, dried at 120 ° C. for 3 minutes, and then irradiated with an electron beam at an acceleration voltage of 200 kV for 5 Mrad, whereby the photocatalyst fine particles were obtained. A photocatalyst bonded to the surface of the coating thin film was obtained by graft polymerization of a silane coupling agent.

Example 4:
The polyester film used for the substrate in Example 1 was irradiated with an electron beam at an acceleration voltage of 200 kV for 10 Mrad, and then an isopropyl alcohol solution containing 1.0% by weight of 3-acryloxypropyltrimethoxysilane having an unsaturated bond. A coating thin film was formed by immersing and graft-polymerizing a silane coupling agent onto the polyester film surface by radicals generated on the film surface and inside by electron beam irradiation. Next, an aqueous solution (NTB-200 manufactured by Showa Denko KK) in which commercially available photocatalyst fine particles are dispersed is applied to the surface of the coating thin film with a bar coater, and then dried at 120 ° C. for 20 minutes, whereby silanol present in the coating thin film is present. A photocatalyst was obtained in which a group and a hydroxyl group present on the surface of the photocatalyst fine particles were bonded by a dehydration condensation reaction.

Example 5:
2-methacryloxypropyltriethoxysilane having an unsaturated bond in a colloidal silica solution (IPA-SZ-S manufactured by Nissan Chemical Industries, Ltd.) in which silica fine particles having an average particle diameter of 10 nm are dispersed in isopropyl alcohol is added to the silica fine particles. After adding 0.0% by weight, it is transferred to a flask equipped with a cooling tube, and then the flask is heated in an oil bath and treated under reflux for 4 hours to form a thin film by dehydration condensation reaction of the silane coupling agent on the surface of the silica fine particles. Formed.

  Moreover, after hydrophilizing the polyester film surface used in Example 1 by corona treatment, the solid content of the silica fine particle dispersion in which the thin film of the silane coupling agent is formed is adjusted to 5.0% by weight, The prepared dispersion was coated on the surface of the polyester film with a bar coater, and dried at 120 ° C. for 5 minutes to form a coating thin film composed of inorganic fine particles. Thereafter, the photocatalyst fine particle dispersion solution used in Example 1 was applied to the coating thin film surface with a bar coater, dried at 120 ° C. for 3 minutes, and then irradiated with an electron beam at an acceleration voltage of 200 kV for 5 Mrad, whereby the photocatalyst fine particles were converted to silane. A photocatalyst bonded to the surface of the coating thin film was obtained by graft polymerization of a coupling agent.

Example 6:
The polyester film used in Example 1 was irradiated with an electron beam at an acceleration voltage of 200 kV for 10 Mrad, and then the polyester film was dispersed in an isopropyl alcohol solution in which silica fine particles on which a thin film of the silane coupling agent used in Example 5 was dispersed. Was coated on the surface of the polyester film by graft polymerization. The coating film was made of silica fine particles on which the thin film was formed by radicals generated on the film surface and inside by electron beam irradiation. After removing the excess inorganic fine particle dispersion by washing, the photocatalyst fine particle dispersion used in Example 1 was applied to the surface of the coating thin film composed of the inorganic fine particles with a bar coater, dried at 120 ° C. for 3 minutes, and then electron beam Was irradiated with 5 Mrad at an acceleration voltage of 200 kV to obtain a photocatalyst in which the photocatalyst fine particles were bonded to the coating thin film surface made of inorganic fine particles by graft polymerization.

Example 7:
The concentration of 3-glycidoxypropyltriethoxysilane having an unsaturated bond used in Example 3 was 10.0% by weight, and alumina having an average particle diameter of 100 nm was dispersed by 30% by weight with respect to the silane coupling agent. A photocatalyst was obtained under the same conditions as in Example 3 except that.

Example 8:
30 wt% of tetraethoxysilane as a silane compound was dispersed in a 5.0 wt% isopropyl alcohol solution of 3-glycidoxypropyltriethoxysilane having an unsaturated bond used in Example 3 with respect to the silane coupling agent. Except for this, a photocatalyst was obtained under the same conditions as in Example 3.

Example 9:
Except that 20% by weight of 3-methacryloxypropyltriethoxysilane was added to the solid content in a solution in which 5% by weight of silica fine particles on which a thin film of the silane coupling agent used in Example 5 was formed was dispersed. A photocatalyst was obtained under the same conditions as in No. 5.

Example 10:
Except for adding 10% by weight of each of 3-methacryloxypropyltriethoxysilane and tetraethoxysilane to the 5% by weight dispersion of silica fine particles on which the thin film of the silane coupling agent used in Example 5 was formed. Obtained a photocatalyst under the same conditions as in Example 5.

Example 11:
10% by weight of 3-methacryloxypropyltrimethoxysilane is added to the photocatalyst fine particle dispersion used in Example 1 based on the solid content of the dispersion, and the photocatalyst fine particle thin film is about 5 times thicker than the bar coater used in Example 1. A photocatalyst was obtained under the same conditions as in Example 1 except that a bar coater capable of forming was used.

Example 12:
A bar coater capable of forming a photocatalyst fine particle thin film about 5 times thicker than the bar coater used in Example 1 by adding 10% by weight of tetraethoxysilane to the solid content of the dispersion solution in the photocatalyst fine particle dispersion used in Example 1. A photocatalyst was obtained under the same conditions as in Example 1 except that was used.

Example 13:
The isopropyl alcohol solution in which the silica particles in which the silane coupling agent thin film used in Example 5 was dispersed in the photocatalyst fine particle dispersion used in Example 1 was dispersed in a weight ratio of photocatalyst fine particles and silica fine particles of 8: 2. Mixed to a ratio. The obtained mixed solution was applied to the polyester film used in Example 1 with a bar coater and dried at 120 ° C. for 3 minutes. Next, the polyester film coated with the mixed solution is irradiated with an electron beam at an acceleration voltage of 200 kV for 10 Mrad, so that the photocatalyst fine particles are mixed with silica fine particles and bonded to the polyester film surface by graft polymerization of a silane coupling agent. A photocatalyst was obtained.

Example 14:
A visible light responsive photocatalyst (MTP621 manufactured by Ishihara Sangyo Co., Ltd.) and hydroxyapatite powder (manufactured by Tomita Pharmaceutical Co., Ltd.) were mixed at a weight ratio of 7: 3, and 5% by weight was added to methanol. Hydrochloric acid was added to adjust the pH to 3.0, and the mixture was pulverized and dispersed to an average particle size of 30 nm by a bead mill. N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride having an unsaturated bond was added to the obtained pulverized dispersed methanol solution at 2.0% relative to the solid content of the pulverized dispersed methanol solution. After adding wt%, transfer to a flask equipped with a cooling tube, heat the flask in an oil bath, and treat it under reflux for 4 hours, thereby dehydrating and condensing the silane coupling agent on the surface of the photocatalyst fine particles and hydroxyapatite fine particles. A thin film was formed by bonding. The average particle size of the fine particles in the obtained pulverized dispersed methanol solution was 25 nm. Next, the polyester film used in Example 1 was coated with a methanol solution in which photocatalyst fine particles on which a silane coupling agent thin film was formed and hydroxyapatite fine particles were dispersed by a bar coater, and then dried under the same conditions as in Example 13. The photocatalyst was obtained by irradiating the photocatalyst fine particles with hydroxyapatite fine particles by being irradiated with an electron beam and bonded to the surface of the polyester film with a silane coupling agent.

Example 15:
Silane coupling by mixing γ-alumina fine particles with photocatalyst fine particles under the same conditions as in Example 14 except that the hydroxyapatite used in Example 14 was replaced with aluminum oxide fine particles (UFA-150 manufactured by Showa Titanium Co., Ltd.). A photocatalyst bonded to the surface of the polyester film with an agent was obtained.

Comparative Example 1:
A bar coater was used on the surface of the polyester film used in Example 1 with a solution obtained by adding 10% by weight of 3-aminopropyltriethoxysilane having no unsaturated bond to the photocatalyst fine particle pulverized dispersion solution obtained in Example 1 to the solid content. And photocatalyst was obtained by drying at 120 ° C. for 60 minutes.

Comparative Example 2:
The photocatalyst fine particles used in Example 1 were added to a fluororesin solution (CTX-102A manufactured by Asahi Glass Co., Ltd.) at 50% by weight based on the solid content of the fluororesin solution, and pulverized and dispersed with a bead mill. The average particle size of the photocatalyst fine particles in the obtained photocatalyst-dispersed fluororesin solution was 580 nm, and the average particle size of the photocatalyst fine particles hardly changed even when the pulverization dispersion time was doubled or more. Next, the photocatalyst-dispersed fluororesin solution was applied to the surface of the polyester film used in Example 1 with a bar coater and dried at 120 ° C. for 30 minutes to obtain a photocatalyst.

<Evaluation of photocatalyst>
The appearance of the obtained photocatalyst was visually observed. Moreover, the catalytic activity of the photocatalyst was evaluated by the decomposability of acetaldehyde gas by the photocatalyst. First, after putting the prepared photocatalyst into a Tedlar pack, 3 L of acetaldehyde having a concentration of about 100 ppm was injected into the Tedlar pack. Next, after standing for about 30 minutes so that the concentration of acetaldehyde in the Tedlar pack becomes constant, a 20 W black light (manufactured by Toshiba Lighting & Technology Corporation, manufactured by Toshiba Lighting & Technology Corporation, so that the ultraviolet light intensity on the sample surface is 1.0 mW / cm ²⁾ . FL20SBLB) was used to irradiate the photocatalyst with ultraviolet rays for 120 minutes. The concentration of acetaldehyde in the Tedlar pack was measured using an acetaldehyde gas detector tube (manufactured by Gastec Co., Ltd.). The catalytic activity was shown as a gas decomposition rate as a relative value when the concentration of acetaldehyde before ultraviolet irradiation was 100.

Further, the durability was evaluated by a weather resistance test. Specifically, using a weather resistance tester (Iwasaki Electric Co., Ltd., iSuper UV Tester), after continuously irradiating ultraviolet rays while spraying ion exchange water every 2 hours for 2 minutes, the appearance is visually observed. The catalytic activity after the test was evaluated by decomposition of acetaldehyde gas. The results are shown in Table 1.

  As the results of Examples 1 to 15 show, the photocatalyst obtained in the present invention is extremely excellent in transparency, confirmed to be a photocatalyst excellent in uniformity, and has a gas decomposition rate. Was very high, indicating that the catalyst activity was excellent. Thereby, it was confirmed that the manufacturing method of this invention can provide the photocatalyst body which was excellent in the uniformity and excellent in the catalyst activity. Further, in the weather resistance test, no change in appearance was observed in the photocatalyst of this example in which a thin film composed of a silane coupling agent or a thin film composed of inorganic fine particles was formed on the surface of the substrate. From the above, it was demonstrated that a photocatalyst having excellent durability can be produced. In contrast to these results, in the comparative example not according to the method of the present invention, the durability is low due to low adhesion strength to the substrate. Furthermore, when a fluororesin is used as the binder, the uniformity, adhesion, It was confirmed that the catalytic activity was low, and it was confirmed that the practicality was poor.

  As described above, the production method of the present invention is a method of immobilizing photocatalyst fine particles on the resin surface by chemical bonding such as graft polymerization of a silane coupling agent, and is produced by hydrolysis of the alkoxy group of the silane coupling agent. The silanol group is firmly chemically bonded to the surface of the photocatalyst fine particles by a dehydration condensation reaction, and further, the vinyl group, epoxy group, styryl group, methacrylo group, acryloxy group, isocyanate group, etc. of the silane coupling agent are unsaturated. The functional group having a double bond is formed by chemically bonding to the surface of the resin substrate by a chemical bond such as graft polymerization by a radical generated by irradiation of radiation. Therefore, since the produced photocatalyst fine particles are firmly bonded to the resin substrate surface by a chemical bond with a silane coupling agent, the fine particles having various functions even when used in a harsh environment according to the method of the present invention. It is possible to supply a fine particle immobilization body excellent in durability, in which detachment or the like hardly occurs. Furthermore, between the photocatalyst particles and the resin substrate, silanol groups formed by hydrolysis of alkoxy groups present in the silane coupling agent are condensed to form a dense silicon oxide thin film. This thin film inhibits the direct contact of the hydroxyl radicals generated on the surface of the photocatalyst particles with the resin substrate, so that the resin substrate surface does not receive the strong oxidation and reduction action of the photocatalyst particles. Further, in the present invention, since a photocatalyst body excellent in transparency can be produced, even if applied to various fields, the appearance design properties thereof are not impaired, and the fibers and the like are selected by selecting treatment conditions. It is possible to provide a method for producing a useful photocatalyst body excellent in practicality that can be applied to various fields, for example, without damaging the texture of the structure.

Claims (8)

  A method for producing a photocatalyst having at least a substrate surface made of a resin, wherein a thin film of a silane coupling agent having an unsaturated bond is formed on the photocatalyst fine particles, and the resin on the substrate surface and the thin film formed on the surface of the photocatalyst fine particles A method for producing a photocatalyst, wherein the photocatalyst is produced by bringing the resin surface into contact with an unsaturated bond present in the thin film.   A method for producing a photocatalyst comprising at least a substrate surface comprising a resin, wherein a thin film of a silane coupling agent having an unsaturated bond is formed on the inorganic fine particles, and a coating thin film comprising the inorganic fine particles formed with the thin film is formed on the substrate surface. Forming a thin film of a silane coupling agent having an unsaturated bond on the photocatalyst fine particles, contacting the coating thin film with the photocatalyst fine particles on which the thin film is formed, and existing on the substrate resin surface and the coating thin film of the inorganic fine particles A method for producing a photocatalyst by chemically bonding an unsaturated bond and an unsaturated bond present in a thin film of photocatalyst fine particles.   The method for producing a photocatalyst according to claim 2, wherein the coating thin film comprising the inorganic fine particles contains a silane coupling agent and / or a silane compound having an unsaturated bond.   A method for producing a photocatalyst comprising at least a substrate surface comprising a resin, wherein a coating thin film comprising a silane coupling agent having at least an unsaturated bond is formed on the substrate surface by graft polymerization, and a silane having an unsaturated bond on a photocatalyst fine particle A thin film of a coupling agent is formed, and the surface of the coating thin film and the photocatalyst fine particles that form the thin film are brought into contact with each other. The coating thin film surface formed of the silane coupling agent and the unsaturated bond existing in the thin film of the photocatalytic fine particles And a method for producing a photocatalyst body obtained by chemical bonding.   The method for producing a photocatalyst according to claim 4, wherein the coating thin film made of the silane coupling agent having an unsaturated bond contains inorganic fine particles.   A method for producing a photocatalyst comprising at least a substrate surface made of a resin, wherein a coating thin film made of a silane coupling agent having an unsaturated bond is formed on the substrate surface by graft polymerization, and photocatalyst fine particles are brought into contact with the coating thin film. A method for producing a photocatalyst, wherein a silanol group present in a coating thin film and a functional group present on the surface of a photocatalyst fine particle are bonded by a dehydration condensation reaction.   The method for producing a photocatalyst according to any one of claims 1 to 5, wherein the chemical bond is graft polymerization.   The method for producing a photocatalyst according to any one of claims 4 to 7, wherein the graft polymerization is radiation graft polymerization.