JP3863620B2 - Photocatalyst and method for producing the same - Google Patents

Description

【００３０】
表１中、明度の差（ΔＬ）はその値が小さいほど照射前後における壁装用ビニールシートの明度の変化が少ないことを示し、赤色−緑色系の色調の差（Δａ）は正の値が大きければ赤色の、負の値が大きければ緑色の、照射前後における壁装用ビニールシートの変色が進んだことを示し、茶色−青色系の色調の差（Δｂ）は正の値が大きければ茶色の、負の値が大きければ青色の、照射前後における壁装用ビニールシートの変色が進んだことを示している。また、色差（ΔＥ）はこれらΔＬ、Δａ、Δｂのそれぞれの平方の和の平方根として求められ、その値が小さいほど照射前後における壁装用ビニールシートの変色度合いが小さいことを示している。表１からすると、アモルファス型過酸化チタンゾル２倍希釈液とそれに対するＳｉＯ₂ の重量比が１％のコロイダルシリカとの混液（０．８５重量％のＴｉＯ₃ と３．３重量％のＳｉＯ₂ を含有）からなるブロック層を用いた場合に、照射前後における壁装用ビニールシートの変色度合いが少なく、もっとも優れたブロック効果が達成しうることがわかった。
【００３１】
【発明の効果】
本発明によると、アモルファス型チタン酸化物とケイ素酸化物とを含むブロック層を介して基体に光触媒を担持させているので、有機高分子樹脂基板や有機高分子樹脂繊維を基体として用いた場合における光触媒による変色や異臭の発生等の悪影響や、無機材を基体として用いた場合における光触媒への悪影響を完全にブロックし得る。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photocatalyst having a substrate carrying a photocatalyst, in particular, a substrate made of an organic polymer material such as an organic polymer resin substrate, an organic polymer resin fiber / nonwoven fabric, or an organic polymer coating film, and the substrate is blocked from the photocatalyst. The present invention relates to a technique for (shielding) and preventing the generation of a strange odor from the substrate due to photocatalytic action and the discoloration of the substrate itself.
[0002]
[Prior art]
The photocatalyst body has a wide range of applications such as environmental protection products such as building base materials and medical devices and instruments utilizing its sterilizing function because it decomposes and detoxifies harmful substances and the like by its photocatalytic function. However, in a photocatalyst body in which a photocatalyst is supported on the surface of an organic polymer material such as an organic polymer resin substrate (plastic plate), the organic polymer material is deteriorated by a photocatalytic action such as an oxidation-reduction reaction. It is known that a polymer material needs to be protected. For example, it is known that a corrosion-resistant metal and a metal oxide are deposited on the surface of an organic polymer resin substrate by sputtering and blocked from a redox reaction (Japanese Patent Laid-Open No. 8-215295). Issue gazette).
[0003]
In addition, a substrate made of an inorganic compound such as a tile or glass having a photocatalyst supported on its surface does not itself deteriorate due to photocatalysis as in the case of an organic polymer resin substrate. The reaction of Na ions, K ions, etc. derived from selenium and photocatalysts such as anatase-type titanium oxide TiO ₂ prevents the photocatalytic function from fully functioning, and the problem is how to block these ions from the inorganic substrate. there were. The inventors previously provided a layer made of amorphous titanium peroxide TiO ₃ or amorphous titanium oxide TiO ₂ having no photocatalytic action as an inactive film by spraying, dipping or the like between the photocatalyst and the substrate. (Japanese Patent Application No. 8-75543).
[0004]
[Problems to be solved by the invention]
As described above, when a photocatalytic function is imparted to an organic polymer material such as an organic polymer resin substrate that is expected and used frequently as a substrate for supporting a photocatalyst, it is between the organic polymer material and the photocatalyst. It is necessary to provide a protective layer. Although the method described in the above-mentioned JP-A-8-215295 can be applied to an organic polymer resin substrate that does not contain a specific additive, generally an organic polymer such as an organic polymer resin substrate or an organic polymer resin fiber is used. In addition to various additives, for example, organic solvents, organic pigments and dyes for coloring are used on the inside and outside of the substrate and the resin. For this reason, gasified organic solvents and pigments and dyes that are vulnerable to oxidation are not used. However, it has been a problem in concretely commercializing a photocatalyst having a substrate made of these organic polymer materials by releasing a strange odor or changing color due to photocatalytic action.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present inventors have conducted intensive research. When the mixture of amorphous titanium oxide and silicon oxide uses the above organic polymer resin substrate or organic polymer resin fiber as a substrate, The present inventors have found that the adverse effects due to the photocatalyst and the negative effects on the photocatalyst when an inorganic material such as tile or glass is used as the substrate can be completely blocked.
[0006]
That is, the present invention provides a substrate comprising a photocatalyst made of an organic polymer material or the like via a block layer containing amorphous titanium oxide such as amorphous titanium peroxide or amorphous titanium oxide and silicon oxide such as colloidal silica. An organic polymer resin sheet containing no additive is further interposed between the block layer and the substrate made of an organic polymer material. The present invention relates to a characteristic photocatalyst.
[0007]
In addition, the organic polymer resin containing no additive is mixed with amorphous titanium oxide such as amorphous titanium peroxide (sol) or amorphous titanium oxide (powder) and silicon oxide such as colloidal silica. The present invention relates to a photocatalyst having a photocatalyst supported on a substrate made of an organic polymer material or the like through a block layer.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, examples of the amorphous titanium oxide include amorphous titanium peroxide TiO ₃ and amorphous titanium oxide TiO ₂ . The titanium peroxide and amorphous type titanium oxide in an amorphous form, unlike the anatase type titanium oxide TiO ₂ and rutile-type titanium oxide TiO _2, the photocatalytic function is substantially little.
[0009]
As the amorphous titanium peroxide used in the present invention, a particularly preferable amorphous titanium peroxide sol can be produced, for example, as follows. Aqueous hydroxide or alkali hydroxide such as sodium hydroxide is added to a titanium salt aqueous solution such as titanium tetrachloride TiCl ₄ . The resulting pale bluish white, amorphous titanium hydroxide Ti (OH) ₄ is also called orthotitanate H ₄ TiO _{4. When} this titanium hydroxide is washed and separated and then treated with hydrogen peroxide, the amorphous of the present invention A titanium peroxide solution in the form is obtained. This amorphous titanium peroxide sol has a pH of 6.0 to 7.0 and a particle diameter of 8 to 20 nm, and its appearance is a yellow transparent liquid and is stable even when stored at room temperature for a long period of time. The sol concentration is usually adjusted to 1.40 to 1.60%, but the concentration can be adjusted as necessary. When using at a low concentration, dilute with distilled water or the like. To do.
[0010]
In addition, this amorphous type titanium peroxide sol is amorphous at room temperature and has not yet been crystallized in anatase type titanium oxide. And a uniform and flat thin film can be formed on a substrate, and the dry film has a property that it does not dissolve in water.
In addition, when the amorphous titanium peroxide sol is heated at 100 ° C. or higher, it begins to change to an anatase type titanium oxide sol having a photocatalytic function. It becomes anatase type titanium oxide by heating.
[0011]
As the amorphous titanium oxide used in the present invention, a fine powder form or a sol form in which this fine powder form is dispersed and suspended in a solvent such as nitric acid is known. Unlike the amorphous titanium peroxide sol, the amorphous titanium oxide having no photocatalytic function has no adhesion itself. Therefore, when it is used for the block layer, It is used by mixing with a binder such as a cured water-soluble resin.
[0012]
Examples of the silicon oxide used in the present invention include silicon dioxide such as colloidal silica, siloxane compounds such as organopolysiloxane, silicone, and water glass. Colloidal silica is preferable.
[0013]
As the block layer in the present invention, a mixture of the above amorphous titanium oxide and silicon oxide, for example, a mixture of amorphous titanium peroxide sol and colloidal silica can be used. This mixture of amorphous titanium peroxide sol and colloidal silica has a feature that it can be fixed and adhered to a substrate from room temperature. The mixing ratio of amorphous titanium oxide and silicon oxide is usually in the range of 1: 0.5 to 1:10 by weight. The layer (coating) made of a mixture of amorphous titanium oxide and silicon oxide has hydrophilicity, antistatic action, and ultraviolet / harmful electromagnetic wave blocking function.
[0014]
The photocatalyst usable in the present _{invention, Ti0 2, ZnO, SrTiO 3} , CdS, Cd0, CaP, InP, In 2 O 3, CaAs, BaTiO 3, K 2 NbO 3, Fe 2 O 3, Ta 2 O 5 , WO ₃ , SaO ₂ , Bi ₂ O ₃ , NiO, Cu ₂ O, SiC, SiO ₂ , MoS ₂ , MoS ₃ , InPb, RuO ₂ , CeO _2, etc. sol anatase titanium oxide Ti0 ₂ is preferred.
[0015]
As described above, a sol-like anatase-type titanium oxide sol, that is, an anatase-type titanium oxide sol, can be produced by heating an amorphous-type titanium peroxide sol at a temperature of 100 ° C. or higher. The anatase-type titanium oxide sol, which varies slightly depending on the heating time, for example, is produced by treatment at 100 ° C. for 6 hours, has a pH of 7.5 to 9.5 and a particle size of 8 to 20 nm, and its appearance is a yellow suspension liquid. is there.
This anatase-type titanium oxide sol is stable even when stored at room temperature for a long time, but may precipitate when mixed with an acid or an aqueous metal solution, and the presence of Na ions impairs photocatalytic activity and acid resistance. There is a case. The sol concentration is usually adjusted to 2.70 to 2.90% by weight, but the concentration can be adjusted as necessary.
[0016]
As the photocatalyst, in addition to the above anatase-type titanium oxide sol, as powdered titanium dioxide, for example, commercially available “ST-01” (made by Ishihara Sangyo Co., Ltd.) and “ST-31” (made by Ishihara Sangyo Co., Ltd.) Can be used. In this case, any binder can be used as long as it does not deteriorate due to the photocatalytic action and does not lower the photocatalytic function. It is desirable to use a titanium oxide sol.
[0017]
A photocatalyst function auxiliary additive metal (Pt, Ag, Rh, RuO, Nb, Cu, Sn, NiO, etc.) can be added to the photocatalyst body in order to promote and supplement the photocatalytic reaction. . Further, before molding, together with the photocatalyst, particles of spontaneous ultraviolet radiation agent or phosphorescent ultraviolet radiation agent or particles mixed with these radiation agents may be mixed.
[0018]
Examples of the substrate on which the photocatalyst is supported include organic polymer materials such as substrates made of organic polymer resins, nonwoven fabrics / fibers, and coating films.
Examples of organic polymer resin substrates used in photocatalytic functional products include sheet materials and molded products of thermosetting resins such as phenol, urea, and polyester, and thermoplastic resins such as polystyrene, ABS, methacryl, polyacid, and polycarbonate. Examples of the raw material resin such as nonwoven fabric and fiber include polyethylene, polypropylene, polyethylene terephthalate, and vinylidene chloride. Also, examples of the coating film include unsaturated polyester, thermosetting epoxy urethane resin, and other weather resistance. Examples thereof include a fluororesin and a silicone resin excellent in properties.
[0019]
Various additives are usually added to the resin material of the organic polymer material used as the base of the photocatalyst body according to the respective use. For example, wall coverings made of polyvinyl chloride include plasticizers that give flexibility, such as ester ester phthalate, dioctyl phthalate, and butanol diesters, and phosphorus, heavy metals such as tin, zinc, and barium. It is known to add higher fatty acid salts such as acid salts and stearates. In addition, in general, red colorants are made by reacting sparingly soluble azo dyes with calcium or magnesium, and as foaming agents, benzenesulfhydrazines and azonidols that generate nitrogen gas by decomposition and cause foaming Compounds are used, and tricresyl phosphate (TCP), halogen-containing monomers or polymers are used as flame retardants for building materials and electrical products. In addition, compounds such as triazoles and acrylonitrile derivatives are added as UV inhibitors.
[0020]
These various additives are combined with those combined, gasified, or ionized by a photocatalytic reaction, and change color or give off a strange odor, thereby hindering commercialization. Moreover, in the wall covering, a base paper is used for the bonding surface, and the above-mentioned disaster prevention agent is immersed, applied, and mixed. Examples of the base material include paper, cloth, aluminum hydroxide paper and the like, and gasified gas from this may cause discoloration and off-flavor due to the photocatalytic function.
[0021]
In addition to the above organic polymer materials, organic materials such as rubber, wood and paper, inorganic materials such as ceramics and glass, and metal materials such as aluminum and steel can be used as the substrate in the present invention.
Further, the size and shape are not limited, and a plate shape, a honeycomb shape, a fiber shape, a filter sheet shape, a bead shape, a foam shape, or a stack of them may be used. In addition, a photocatalyst layer can be provided on the inner surface of the substrate that passes ultraviolet rays through the block layer, and can also be applied to coated articles.
[0022]
Examples of the photocatalyst formed by supporting a photocatalyst on a substrate such as an organic polymer material through a block layer in the present invention include the following forms and structures.
(1) A photocatalyst having a block layer (second layer) provided on a substrate (first layer) such as an organic polymer material, and further provided with a photocatalyst layer (third layer).
(2) A photocatalyst comprising a sheet having a thickness of 10 μm or more made of polypropylene, polyethylene terephthalate, fluororesin or the like not containing an additive between the first layer and the second layer. In this case, the blocking effect is more reliable than that of the photocatalyst of the above (1).
(3) Other examples of the block layer include those in which a thermosetting unsaturated polyester resin, epoxy resin, alkyd resin, silicon resin, etc. are dissolved in a solvent or water and the viscosity is adjusted. The thing which consists of a mixture with an oxide can be illustrated, The photocatalyst body which apply | coated this to the thickness of about 1 micrometer-50 micrometers on the base | substrate, and was used as the 2nd layer. In the process of laminating and fixing this block layer to the substrate, amorphous titanium oxide particles are exposed on the surface, and as a result, the same blocking effect as in the photocatalyst of (2) above in which the sheet layer and the block layer are provided. Thus, a photocatalyst body having the following is formed.
[0023]
Examples of the method for laminating and fixing the block layer of the present invention include a method of forming a thin film by a method such as a sol-gel method, sputtering, thermal spraying, spray coating, dipping, spin coating, etc. Can be achieved, and the film-forming performance of a mixture of amorphous titanium oxide and silicon oxide constituting the block layer. For example, in the case of a block layer made of amorphous titanium peroxide sol and colloidal silica, 0 The blocking effect can be exhibited at a thickness of 0.05 to 5 μm. Moreover, conventionally known methods and thicknesses are appropriately used for the method of laminating and fixing the photocatalyst layer and the thickness of the photocatalyst layer.
[0024]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, the technical scope of the present invention is not limited to these examples.
Reference Example 1 (Production of amorphous type titanium peroxide sol)
Titanium tetrachloride TiCl ₄ 50% solution (Sumitomo Citizens Co., Ltd.) diluted 70 times with distilled water and ammonium hydroxide NH ₄ OH 25% solution (Takasugi Pharmaceutical Co., Ltd.) 10 times with distilled water The diluted product is mixed at a volume ratio of 7: 1 to carry out a neutralization reaction. After the neutralization reaction, the pH is adjusted to 6.5 to 6.8, and after standing for a while, the supernatant is discarded. Add distilled water about 4 times the gel amount of the remaining Ti (OH) ₄ and stir well. Check with silver chloride and repeat washing with water until chlorine ions in the supernatant are no longer detected. Finally, discard the supernatant and leave only the gel. In some cases, dehydration can be performed by centrifugation. When 210 ml of 35% hydrogen peroxide solution was added to 3600 ml of pale blue white Ti (OH) ₄ in 30 minute portions and stirred at about 5 ° C. overnight, about 2500 ml of yellow transparent amorphous titanium peroxide sol Is obtained.
In addition, in the above steps, if heat generation is not suppressed, a substance insoluble in water such as metatitanic acid may be deposited. Therefore, it is desirable to perform all steps while suppressing heat generation.
[0025]
Reference Example 2 (Production of titanium oxide sol from amorphous titanium peroxide sol)
When the amorphous titanium peroxide sol is heated at 100 ° C., anatase type titanium oxide is produced after about 3 hours, and when heated for about 6 hours, an anatase type titanium oxide sol is obtained. Moreover, when heated at 100 ° C. for 8 hours, it is slightly yellowish and has a yellow fluorescence, and when concentrated, a yellow opaque product is obtained, and when heated at 100 ° C. for 16 hours, an extremely light yellow product is obtained. The dry adhesion is somewhat lower than that heated at 100 ° C. for 6 hours.
Since this titanium oxide sol has a lower viscosity than amorphous titanium peroxide, it is concentrated to 2.5% by weight so that it can be easily dipped.
[0026]
Example 1 (block effect)
As the substrate, a vinyl sheet for wall covering containing an organic solvent (Achilles, 100 × 100 mm, thin ivory color) was used. As the block layer, an amorphous titanium peroxide sol (containing 1.7% as TiO ₃ ) was diluted with deionized water 2 times, 6 times, 10 times and 14 times, and colloidal silica. The weight ratio of SiO ₂ to TiO ₃ (Nissan Chemical Co., Ltd., trade name Snowtex, containing 20.7% as SiO ₂ ) is 0%, 0.5%, 1%, 2%, and 8%, respectively. The substrate was coated using 20 kinds of mixing ratios mixed as described above. For the coating, a spray gun FS-G05-1 having a round blow nozzle with a diameter of 0.5 mm manufactured by Meiji Kikai Co., Ltd. was used, the spraying amount was 0.2 g / sheet, and after spraying, it was dried at 80 ° C.
[0027]
As the photocatalyst, 1.7 g of anatase type titanium oxide “ST-01” manufactured by Ishihara Sangyo Co., Ltd. and 200 g of the above-mentioned amorphous type titanium peroxide sol (containing 1.7% as TiO ₃ ) diluted twice are mixed. Using a spray gun FS-G05-1 having a round blow nozzle with a diameter of 0.5 mm manufactured by Meiji Kikai Co., Ltd., the spray amount is 0.2 g / sheet on the one where the block layer is laminated, After spraying, it was dried at 80 ° C.
[0028]
In the block test, a black light emitting a single wavelength of 380 nm was irradiated for 39 hours from a distance of 10 mm, and using a color difference meter manufactured by Minolta Camera Co., Ltd., the difference in lightness (ΔL) before and after irradiation and the red-green color tone Color difference (Δa), brown-blue color tone difference (Δb), and color difference (ΔE) obtained by combining them were examined for the degree of discoloration. The results are shown in Table 1.
[0029]
[Table 1]

[0030]
In Table 1, the lightness difference (ΔL) indicates that the smaller the value, the smaller the change in lightness of the wall-mounted vinyl sheet before and after the irradiation, and the red-green color tone difference (Δa) has a larger positive value. If the negative value is large, it indicates that the color change of the wall-mounted vinyl sheet before and after irradiation has progressed, and the brown-blue color tone difference (Δb) is brown if the positive value is large. If the negative value is large, it indicates that the discoloration of the wall-mounted vinyl sheet before and after irradiation has progressed in blue. The color difference (ΔE) is obtained as the square root of the sum of the squares of ΔL, Δa, and Δb, and the smaller the value, the smaller the color change degree of the wall mounted vinyl sheet before and after irradiation. According to Table 1, a mixture of an amorphous titanium peroxide sol two-fold diluted solution and colloidal silica having a SiO ₂ weight ratio of 1% (0.85 wt% TiO ₃ and 3.3 wt% SiO ₂ is mixed). It was found that when the block layer made of (containing) was used, the degree of discoloration of the wall-mounted vinyl sheet before and after irradiation was small, and the most excellent blocking effect could be achieved.
[0031]
【The invention's effect】
According to the present invention, since the photocatalyst is supported on the substrate through the block layer containing amorphous titanium oxide and silicon oxide, the organic polymer resin substrate or the organic polymer resin fiber is used as the substrate. It is possible to completely block adverse effects such as discoloration and off-flavor generation caused by the photocatalyst, and adverse effects on the photocatalyst when an inorganic material is used as the substrate.

Claims (7)

A photocatalyst comprising a photocatalyst supported on a substrate through a block layer containing amorphous titanium oxide and silicon oxide. The photocatalyst body according to claim 1, wherein an organic polymer resin sheet containing no additive is further interposed between the block layer and the substrate. A photocatalyst comprising a photocatalyst supported on a substrate through a block layer formed by mixing an amorphous titanium oxide and a silicon oxide with an organic polymer resin containing no additive. The photocatalyst according to any one of claims 1 to 3, wherein the substrate is made of an organic polymer material. The photocatalyst body according to any one of claims 1 to 4, wherein the amorphous titanium oxide is an amorphous titanium peroxide sol. The photocatalyst according to any one of claims 1 to 5, wherein the silicon oxide is colloidal silica. The photocatalyst according to any one of claims 1 to 6, wherein a mixture of anatase type titanium oxide particles or titanium oxide powder and an amorphous type titanium peroxide sol is used as the photocatalyst.