WO2008018178A1

WO2008018178A1 - Photocatalyst, method for producing the same, photocatalyst dispersion containing photocatalyst, and photocatalyst coating composition

Info

Publication number: WO2008018178A1
Application number: PCT/JP2007/000855
Authority: WO
Inventors: Takashi Nabeta; Satoru Miyazoe; Nobuhiko Horiuchi; Hiroshi Suizu; Toru Nonami
Original assignee: Mitsui Chemicals, Inc.
Priority date: 2006-08-10
Filing date: 2007-08-08
Publication date: 2008-02-14
Also published as: JP2009268943A; TW200831186A

Abstract

Disclosed is a photocatalyst comprising a base having a photocatalytic activity and a silicon oxide film covering the base. The photocatalyst further comprises a compound containing phosphorus and calcium, while satisfying the following conditions (a) and (b): (a) the phosphorus content is not less than 0.1% by weight but not more than 10% by weight; and (b) the calcium content is not less than 0.2% by weight but not more than 20% by weight.

Description

Specification

Photocatalyst, process for producing the same, photocatalyst dispersion containing photocatalyst, and photocatalyst coating composition

Technical field

[0001] The present invention relates to a photocatalyst, and in its use, a photocatalyst characterized by protecting an organic polymer as a substrate from the photocatalytic function, a method for producing the photocatalyst, a photocatalyst dispersion containing the photocatalyst, and a photocatalyst Concerning photocatalyst coating composition

CO

Background art

[0002] When crystalline titanium oxide is irradiated with light having a wavelength greater than the band gap, it is photoexcited to generate electrons and holes. These electrons and holes generate active oxygen species such as superoxide ions and hydroxyl radicals on the surface of titanium oxide, and develop strong oxidizing power. Using this photocatalytic reaction, the so-called antifouling effect and sterilization of contaminating components and malodorous components adsorbed on titanium oxide by oxidizing and detoxifying them, or by decomposing organic substances such as oil into carbon dioxide and water It is known to impart an effect to a substrate.

Here, the pollutants and odor components include nitrogen oxides, inorganic compounds such as ammonia, organic compounds such as organic halogens, aldehydes, and lower fatty acids.

[0004] As described above, crystalline titanium oxide, particularly anatase-type titanium oxide, exhibits various excellent actions based on the photocatalytic reaction. These functions are applied to exterior materials such as building materials, tiles, and bricks, wallpaper materials, interior materials such as ceiling materials, ceiling materials, or base materials represented by textiles such as clothes and strength materials, binders, etc. In general, the photocatalyst is expressed in a state in which the photocatalyst is fixed. For this reason, a technique for immobilizing a photocatalyst on a base material has been developed that maintains antifouling, deodorization, and antibacterial action, and does not peel or lose for a long period of time.

[0005] However, when the base material is an organic polymer such as a resin plate, a film, or a fiber, In some cases, the base material itself is oxidatively decomposed by the photocatalytic action. If these base materials are decomposed and deteriorated, cracks and cracks may occur, and the photocatalyst may be peeled off from the base material. As a result, adverse effects such as the loss of photocatalysis, the physical properties of the substrate itself being reduced, and the appearance of the surface being damaged due to the creation of holes that are chewy or worm-like are generated.

[0006] Therefore, in applications that do not require photocatalytic action, such as white pigments for paints, rutile titanium oxide with a low photocatalytic activity is used, or the surface is made of silica or alumina for rutile titanium oxide. The device has been devised to prevent the development of photocatalytic action by coating with.

[0007] On the other hand, when antifouling, deodorizing, and antibacterial purposes are required, that is, when the development of a photocatalytic action is required, various measures have been taken when using the photocatalyst. For example, a method has been reported in which a porous inorganic substance or a crystalline inorganic substance is coated on the surface of a photocatalyst to prevent direct contact between the organic base material and the photocatalyst and to suppress decomposition of the organic base material (patent) References 1, 2, and 3). In these reported examples, although the decomposition of the organic substrate is suppressed, the amount of ultraviolet rays absorbed by the titanium oxide is reduced by the porous inorganic material or the crystalline inorganic material, and the active points on the titanium oxide are also reduced. Will be reduced. As a result, the photocatalytic action decreases.

[0008] In addition, an active blocking layer made of a silicone resin, a fluororesin, or other inorganic compound is installed between the organic base material and the photocatalyst layer to prevent direct contact between the organic base material and the photocatalyst. A method for suppressing the deterioration of the organic base material has also been studied (Patent Documents 4 and 5). According to this method, it is possible to suppress deterioration of the organic base material. However, due to the multi-layer structure, there is a concern that the processing cost will be expensive. In addition, problems remain in the adhesion stability of the organic substrate and the active blocking layer, and the active blocking layer and the photocatalytic layer.

[0009] Also, when applying a photocatalyst layer containing a binder onto an organic base material, a method of suppressing decomposition / deterioration of the base material by tilting the photocatalyst contained in the photocatalyst layer containing the binder. Have also been reported (Patent Documents 6 and 7). That is, as it approaches the outer surface from the adhesion surface with the base material, the photocatalyst concentration is increased, and the base material is reduced. This is a method for improving qualitative properties. Even in this method, the contact between the substrate and the photocatalyst is not completely prevented, and therefore, it cannot be said that the deterioration of the organic substrate can be completely suppressed.

Patent Document 1: Japanese Patent Application Laid-Open No. 09-27 6 7 06

Patent Document 2: Japanese Laid-Open Patent Publication No. 10-2-4 4 1 6 6

Patent Document 3: Japanese Patent Laid-Open No. 2 0 0 3 _ 2 4 7 9 7

Patent Document 4: Japanese Patent Laid-Open No. 08-8-14 1 500 3

Patent Document 5: Japanese Patent Laid-Open No. 09-9-2 2 9 4 9 3

Patent Document 6: Japanese Patent Application Laid-Open No. 11-0 1 0 8 0 3

Patent Document 7: Japanese Patent Laid-Open No. 2 00 0 _ 0 7 1 3 60

Disclosure of the invention

[0010] The present invention has been made in view of the situation as described above, and while maintaining sufficiently photocatalytic functions such as antifouling, deodorizing, and antibacterial, an organic polymerization serving as a base material in use thereof The present invention relates to a photocatalyst capable of suppressing deterioration of a product, a production method thereof, a photocatalyst dispersion containing a photocatalyst, and a photocatalyst coating composition containing a photocatalyst.

[001 1] As a result of diligent studies to solve the above-mentioned problems, the present inventors have coated a substrate having photocatalytic activity with a silicon oxide film, and further, from phosphorus and calcium in a simulated body fluid in which a calcium phosphate cluster exists. The photocatalyst which precipitated the compound which becomes was discovered. That is, when this photocatalyst is used for exterior materials, interior materials, textile products, etc., it has been found that it can maintain the sufficient photocatalytic function and can suppress deterioration of the organic polymer as the base material. The invention has been completed.

[0012] That is, the present invention provides [1] to [20].

[1] a substrate having photocatalytic activity;

A silicon oxide film covering the substrate;

Further including compounds containing phosphorus and calcium,

A photocatalyst satisfying the following conditions (a) and (b): (a) The phosphorus content is 0.1 wt% or more and 10 wt% or less. (b) The calcium content is 0.2 wt% or more and 20 wt ⁰ / o or less.

[0013] Here, the contents of phosphorus and calcium described above are expressed in wt% based on the weight of the entire photocatalyst.

[2] The compound containing phosphorus and calcium is formed on the surface of the silicon oxide film and / or on the surface of the substrate not covered with the silicon oxide film as an immobilized product containing the compound. The photocatalyst according to [1], which is located.

[3] The photocatalyst according to [2], wherein the silicon oxide film is a fired film.

[4] The photocatalyst according to [3], wherein the fired film is a fired film fired at 400 ° C or higher.

[5] The photocatalyst according to [4], wherein the silicon oxide film has no pores in a pore diameter distribution measurement in a region of 20 to 500 angstroms by a nitrogen adsorption method.

[6] The photocatalyst according to [5], wherein the amount of silicon supported per 1 m ² of the surface area of the substrate having the silicon oxide film is 0.1 mg or more and 2. Omg or less.

[7] The photocatalyst according to [6], wherein the substrate is an anatase type, a rutile type, or a titanium oxide containing a mixture thereof.

[8] The photocatalyst according to [7], wherein the substrate is a particle.

[9] A method for producing a photocatalyst according to [1], comprising the following steps:

(A) an aqueous medium containing the substrate and a silicate, an aqueous medium containing a silicate, the substrate, and

Mixing at least one set selected from the group consisting of an aqueous medium containing the substrate and an aqueous medium containing silicate, and obtaining a photocatalyst having a silicon oxide film on the substrate

(B) a step of separating the photocatalyst obtained in the step (A) from the aqueous medium,

(C) a step of firing the photocatalyst obtained in the step (B) at 400 ° C or higher,

(D) forming an immobilized product containing a compound containing phosphorus and calcium on the surface of the photocatalyst obtained in the step (C) using an aqueous solution of a compound containing phosphorus and a compound containing calcium; (E) separating the photocatalyst obtained in the step (D) from the aqueous solution,

(F) a step of heat-treating the photocatalyst obtained in the step (E) at 50 ° C to 700 ° C;

And a pH of the mixed solution containing both the substrate and the silicate in the step (A) is maintained at 5 or less.

[10] The method for producing a photocatalyst according to [9], wherein, in the step (C), the photocatalyst obtained in the step (B) is dried and then calcined.

[1 1] The method for producing a photocatalyst according to [1 0], wherein in the step (C), the photocatalyst obtained in the step (B) is calcined at 1 200 ° C. or less.

[1 2] and with the aqueous solution of the compound and compounds containing calcium containing phosphorus, N a CI, N a HC0 3, N a 2 H P0 4, N a H 2 P0 4, KC I, KHC 0 3, K ₂ H P0 ₄ , KH ₂ P0 ₄ , Mg CI ₂ , Ca CI ₂ , Na ₂ S 0 ₄ , Na F, HC I, and (CH ₂ OH) ₃ CNH ₂ [1 1] The method for producing a photocatalyst according to [1 1], wherein a simulated body fluid obtained by dissolving the compound in water is used.

[1 3] The simulated body fluid is Na +: 1 20 to 1 60 mM, K +: 1 to 20 mM, Ca ²⁺ : 0.5 to 50 mM, Mg ²⁺ : 0.5 to 50 mM, CI _: 80 to 2 _{O OmM, H C0 3 -:} 0. 5~30mM, HP 0 4 2 _: "! ~ 20mM, S 0 4 2 -: 0."! The method for producing a photocatalyst according to [1 2], which is an aqueous solution containing ˜2 OmM and F−: 0 to 5 mM.

[1 4] A photocatalyst dispersion comprising the photocatalyst according to [1], a liquid medium, and a dispersion stabilizer.

[1 5] The photocatalyst dispersion liquid according to [1 4], wherein the liquid medium is water.

[16] The photocatalyst dispersion liquid according to [14], wherein the dispersion stabilizer is an ionic surfactant.

[1 7] A photocatalyst coating composition comprising the photocatalyst according to [1], a liquid medium, and a binder.

[1 8] Including a compound containing titanium or silicon as the binder, [1 [7] The photocatalytic coating composition according to [7].

[19] The photocatalyst coating composition according to [18], wherein the titanium-containing compound is a compound containing titanium peroxide.

[20] The photocatalyst coating composition according to [17], which contains water and / or alcohol as the liquid medium.

[0015] According to the present invention, it is possible to reduce the degradation and deterioration of an organic polymer that comes into contact with the photocatalyst while maintaining the photocatalytic function, which is difficult when using a commercially available photocatalyst made of titanium oxide or the previously reported technology. It is possible to provide a photocatalyst capable of being suppressed, a production method thereof, a photocatalyst dispersion containing the photocatalyst, and a photocatalyst coating composition containing the photocatalyst.

Brief Description of Drawings

[0016] The above-described object and other objects, features, and advantages will be further clarified by the preferred embodiments described below and the following screens that accompany it.

[Figure 1] Iog differential pore volume distribution curve (solid line) of photocatalyst 1 and Iog differential pore volume distribution curve (dotted line) of photocatalyst (photocatalyst 4) that does not have a silicon oxide film corresponding to the base of this photocatalyst FIG.

FIG. 2-A is a diagram showing the photodegradation activity of photoaldehyde 1 to photoacetaldehyde.

FIG. 2-B is a diagram showing the photodegradation activity of photoaldehyde 1 to 5 with acetaldehyde.

FIG. 3 is a graph showing the weight residual ratio of a film made of photocatalysts 1 to 5 and polyacrylic acid.

BEST MODE FOR CARRYING OUT THE INVENTION

[0017] The photocatalyst according to the present invention includes a substrate having photocatalytic activity, a silicon oxide film covering the substrate, and a compound containing phosphorus and calcium, and the following conditions (a) and (b) (A) Phosphorus content is 0.1 wt% or more and 10 wt% or less, (b) Calcium content is 0.2 wt% or more and 20 wt% or less.

In the present specification, “photocatalyst coated with a silicon oxide film” has a photocatalytic function. This means that the surface of the substrate is coated with a film made of silicon oxide. Therefore, the photocatalyst is formed later in the presence of silicon oxide, which includes the photocatalyst immobilized on silicon oxide, and the complex in which silicon oxide and photocatalyst are formed in parallel in the same container are included. I can't.

[0019] The aspect in which the silicon oxide film covers the substrate is not particularly limited, and includes both an aspect in which a part of the substrate is covered and an aspect in which the whole is covered. From the viewpoint of obtaining higher photolytic activity, it is preferable that the surface of the substrate is uniformly coated with a film made of silicon oxide.

Here, the silicon oxide film may be in the form of an unfired film or a fired film. In the present invention, a fired film of silicon oxide after firing is preferred.

As the substrate having photocatalytic activity (hereinafter abbreviated as “substrate” as appropriate), a metal compound photo-semiconductor can be used. Examples of the metal compound optical semiconductor include titanium oxide, zinc oxide, tungsten oxide, and titanium titanate. Of these, titanium oxide is preferable because of its excellent photocatalytic activity, harmlessness and excellent stability. Examples of titanium oxide include amorphous, anatase type, rutile type, and brookite type. Of these, the anatase type or rutile type, which are excellent in photocatalytic activity, or a mixture thereof is more preferred, and these may contain a small amount of amorphous material.

[0022] As a substrate, one or more transition metals added to a metal compound optical semiconductor, one or more typical elements of group 14, 15 and / or 16 added to a metal compound semiconductor An optical semiconductor composed of two or more metal compounds and a mixture of two or more metal compound semiconductors may be used.

[0023] Furthermore, it is preferable to use particles of a metal compound optical semiconductor as the substrate. In addition, for example, a molded body, a fiber, a coating film, or the like in which a part of the surface of the metal compound optical semiconductor is exposed can be used. The substrate preferably contains a metal compound optical semiconductor having a specific surface area of 30 m ² / g or more.

[0024] Unless the substrate can be clearly recognized as particles, the specific surface area of the substrate fixed on a molded body, fiber, coating film, etc. Cannot be used for the T method. In such a case, the primary particle diameter obtained from X-ray diffraction analysis and Sierra set calculation or primary particle observation using an electron microscope is used as the basis. Then, the “surface area” is calculated in spherical form. In addition, the crystal phase is grasped from diffraction analysis of X-rays and electron beams, and the “weight” is calculated from the true density of the crystal phase and the volume obtained from the above spherical conversion. This makes it possible to determine the specific surface area.

[0025] In the measurement of the pore size distribution in the region of 20 to 500 angstroms by the nitrogen adsorption method, the silicon oxide film has no pores is used as a raw material when producing a photocatalyst coated with a silicon oxide film. When comparing the pore size distribution in the region of 20 to 500 angstroms, the substrate having photocatalytic activity and the photocatalyst coated with a silicon oxide film prepared using the substrate having photocatalytic activity are oxidized. It means that there are substantially no pores in the silicon film. Specifically, the pore size distribution of a photocatalyst including a substrate having photocatalytic activity and a substrate provided with a silicon oxide film is grasped by pore distribution measurement such as a nitrogen adsorption method. Then, by comparing these, it can be determined whether or not there are substantially no pores in the silicon oxide film.

More specifically, the grasping method in the nitrogen adsorption method can determine the presence or absence of pores in the silicon oxide film by the following methods (1) to (4). Here, an example using photocatalyst particles as a substrate will be described.

(1) After drying the photocatalyst particles at 200 ° C, measure the N ₂ adsorption isotherm during the desorption process.

(2) Measure the N ₂ adsorption isotherm during the desorption process of the photocatalyst coated with a silicon oxide film

(3) Analyzing the two N ₂ adsorption isotherms by the BJH (Barrett-Joyner-H alenda) method, the region of 20 to 500 angstroms is analyzed.

Obtain an I o g differential pore volume distribution curve.

(4) Comparing the two I og differential pore volume distribution curves, the I og differential pore volume of the photocatalyst coated with the silicon oxide film is less than the I og differential pore volume of the photocatalyst particle. If there is no area larger than 1 ml / g, it is determined that the silicon oxide film has no substantial pores. If there is an area larger than 0.1 mI / g, silicon oxide It is determined that the membrane has pores. It should be noted that 0.1 ml / g or more is because, in the pore distribution measurement by the nitrogen adsorption method, an Iog differential pore volume value often causes a measurement error of about 0.1 m I / g width. It is.

[0027] By comparing two I og differential pore volume distribution curves in the range of 20 to 500 angstroms, the presence or absence of pores in the silicon oxide film can be substantially determined.

[0028] It should be noted that the two I og differential pore volume distribution curves were compared, and the I og differential pore volume of the photocatalyst coated with the silicon oxide film in the region of 10 to 1 000 angstroms More preferably, there is no region larger than the differential pore volume by 0.1 mI / g or more.

[0029] Here, when the silicon oxide film has pores, it is difficult to improve the photolytic activity. The reason for this is not necessarily clear, but the presence of pores facilitates light scattering and reflection at the silicon oxide film, reducing the amount of ultraviolet light reaching the substrate having photocatalytic activity, and increasing the positive polarity due to photocatalytic excitation. This is presumably due to a decrease in the generation of holes and electrons. In addition, when coated with the same amount of silicon oxide, the thickness of the silicon oxide film increases by the volume of the pores for those with pores compared to those without pores. It is assumed that sufficient photolytic activity cannot be obtained because the physical distance from the organic substance that is the target of decomposition increases.

[0030] Silicon supported amount per surface area of 1 m ² of the photocatalyst and the silicon oxide film coated according to the present invention, a silicon content containing photocatalyst coated silicon oxide film, the surface area of the photocatalyst coated with a silicon oxide film Is a calculated value calculated from The amount of silicon supported per 1 m ² of the surface area of the photocatalyst coated with the silicon oxide film is 0.1 mg or more and 2. Omg or less, preferably 0.1 mg per 1 m ^{2 of the} surface area. 2 mg or more and 1.5 mg or less, more preferably 0.16 _§ or more and 1.25 mg or less, and further preferably 0.18 mg or more and 1.25 mg or less. If it is less than 0.1 mg, the photocatalytic activity improvement effect by the silicon oxide film is small. Meanwhile, 2. Om If it exceeds g, the ratio of the substrate to the photocatalyst coated with the silicon oxide film is too low, so that the photocatalytic function is hardly improved. By making the silicon loading in the above range, the effect of improving the photocatalytic activity by the silicon oxide film becomes remarkable.

[0031] The surface area of the photocatalyst was measured using a BET specific surface area measuring device using nitrogen adsorption / desorption after heat treatment at 15 ° C for 15 minutes in a dry gas stream with a dew point of -195.8 ° C or less. Can be measured.

[0032] In the method for coating a silicon oxide film according to the present invention, when a silicon oxide film is coated on a substrate existing in an aqueous medium using a silicate, the pH of the mixed solution containing both the substrate and the silicate is 5 The following is maintained.

[0033] The conventional method for producing a photocatalyst having a structure covered with a silicon oxide film has the following problems.

(A) The raw material for the silicon oxide film is expensive.

(B) Explosion-proof expensive dedicated equipment is required because alcohol is produced as a by-product during production and / or because organic media are used.

(C) Since the treatment is performed in the gas phase, it is difficult to arbitrarily control the amount of silicon supported, and it is difficult to manufacture by stably controlling the amount of silicon supported.

(D) Since waste liquid containing dangerous substances such as alcohol is generated, the treatment becomes complicated.

(E) A silicon oxide film having pores is formed to cover the pH region where the silicate compound gels quickly.

On the other hand, in the manufacturing method according to the present invention, since silicate is used as a raw material, the raw material for the silicon oxide film can be made inexpensive. In addition, no alcohol is produced as a by-product during manufacturing. Also, when only water is used as the aqueous medium, no organic medium or alcohol is used. As a result, expensive explosion-proof specialized equipment is not required, and waste liquid treatment is not complicated.

[0035] Furthermore, since the treatment can be performed in the liquid phase, it is relatively easy to arbitrarily control the amount of silicon supported. In addition, when the silicon oxide film is coated on the substrate, the PH of the mixed solution containing both the substrate and silicate is set to 5 or less. Therefore, silicidation A solution containing the compound can be stably present, and silicon oxide having substantially no pores can be formed on the surface of the substrate.

[0036] In the above production method, examples of the aqueous medium include water or a mixed liquid containing water as a main component and containing an organic solvent that is soluble in water among aliphatic alcohols, aliphatic ethers, and the like. . Specific examples of the aqueous medium include water and a mixed liquid of water and methyl alcohol, water and ethyl alcohol, water and isopropanol, and the like. Of these, water is preferred. In addition, these water and mixed liquids can be used alone or in combination of two or more. Further, in order to improve the dispersibility or solubility of the substrate, the aqueous medium includes an organic solvent that can be dissolved in water among aliphatic alcohols, aliphatic ethers, etc., and aliphatic amines, Surfactants such as aromatic polyethers and gelatins can also be mixed.

[0037] As the silicate, silicic acid and / or an oligomer thereof may be used, and two or more kinds may be mixed and used. Sodium salt and potassium salt are preferable from the viewpoint of easy industrial availability, and a sodium silicate aqueous solution (JISK 140 8 "water glass") is more preferable because the dissolution step can be omitted.

[0038] When a silicon oxide film is coated with a silicate on a substrate existing in an aqueous medium, the aqueous medium, the substrate, and the silicate are mixed, and then this mixed solution is aged.

[0039] Specifically,

(i) an aqueous medium containing a substrate and a silicate,

(i i) an aqueous medium and substrate containing silicate, and

(ii) an aqueous medium containing a substrate and an aqueous medium containing a silicate,

A coating method comprising a step of mixing at least one of the above and a step of aging the mixed solution. In the aging process, the coating of the silicon oxide film on the substrate gradually proceeds.

[0040] At this time, it is necessary to maintain the pH of the mixed solution containing both the substrate and the silicate at 5 or less, and it is more preferable to set the acidic region to pH 0 or more and pH 4 or less. Good. When the pH is maintained at 5 or less in the absence of the substrate, the condensate of silicic acid compounds hardly precipitates alone from silicic acid, silicic acid ions and / or oligomers thereof. On the other hand, when the pH is maintained below 5 in the presence of the substrate, the surface of the substrate acts as a condensation catalyst for the silicate compound, and a silicon oxide film is rapidly formed only on the surface of the substrate. That is, the acidic region having a pH of 5 or less is a region in which a solution containing a silicic acid compound can be stably present and silicon oxide can be formed into a film on the surface of the substrate.

[0041] Also in the basic region of pH 11 or higher, when a solution containing silicic acid, silicate ions and / or oligomers thereof is ripened as in the acidic region of pH 5 or lower, the condensate of the silicic acid compound Is difficult to precipitate. However, since only a part of the used silicate forms a silicon oxide film, it is not preferable. Further, since the pH range of 6 to 11 is likely to produce a condensate of a silicate compound, that is, silicon oxide fine particles and / or gel, the silicon oxide film becomes porous or locally on the surface of the substrate. In particular, silicon oxide may be formed.

[0042] When an organic medium such as alcohol is present in an aqueous medium, the pH cannot be accurately measured with a pH electrode for water. Therefore, measurement is performed using a pH electrode for an aqueous solution containing an organic medium. To do. Separately, it is possible to measure the pH by replacing the organic medium with the same volume of water.

[0043] As a method of maintaining the mixed solution containing both the substrate and the silicate at a pH of 5 or less, the pH of the aqueous medium is always measured when the substrate, the silicate, and the aqueous solvent are mixed and aged. In addition, a method of adjusting by adding an acid and a base may be used as appropriate. However, it is easy to neutralize the total amount of the base components contained in the silicate used in the production and to have an amount of acid sufficient to be lower than pH 5 in the aqueous medium in advance.

[0044] Although any acid can be used as the acid, mineral acids such as hydrochloric acid, nitric acid, and sulfuric acid are preferably used. Only one kind of acid may be used, or two or more kinds of acids may be mixed and used. Of these, hydrochloric acid and nitric acid are preferred. When sulfuric acid is used, if a large amount of sulfur remains in the photocatalyst, the adsorption efficiency may deteriorate over time. photocatalyst The sulfur content therein is preferably 0.5% by weight or less, more preferably 0.4% by weight or less, based on the total weight of the photocatalyst.

[0045] For the base, the total amount of the base components contained in the silicate is neutralized, and a sufficient amount of acid is previously present in the aqueous medium so that the pH is 5 or less. There is no need to use it separately. However, when using a base, any base can be used. Of these, alkali metal hydroxides such as potassium hydroxide and sodium hydroxide are preferably used.

[0046] The reaction conditions such as reaction temperature and reaction time when the mixed solution is aged and the silicon oxide film is coated on the substrate are conditions that do not adversely affect the formation of the target silicon oxide film. If there is no particular limitation. The reaction temperature is preferably 10 ° C. or higher and 20 ° C. or lower, more preferably 20 ° C. or higher and 80 ° C. or lower. When the reaction temperature is too low, the condensation of the silicate compound is difficult to proceed, so that the formation of the silicon oxide film is remarkably delayed and the productivity may be deteriorated. If the reaction temperature is too high, a condensate of a silicate compound, that is, silicon oxide fine particles and / or gel, etc. is likely to be generated, so that the silicon oxide film becomes porous or silicon oxide is locally formed on the substrate surface. It may be done.

[0047] The aging time is preferably 10 minutes or more and 500 hours or less, and more preferably 1 hour or more and 100 hours or less. If the aging time is too short, the coating with the silicon oxide film does not proceed sufficiently, and the effect of improving the photolytic activity by the coating may not be sufficiently obtained. When the aging time is too long, the substrate having photocatalytic activity is sufficiently covered with the silicon oxide film and the photodegradation activity is improved, but the productivity may be deteriorated.

[0048] The concentration of the substrate having photocatalytic activity contained in the mixed solution is preferably 1% by weight or more and 50% by weight or less, and more preferably 5% by weight or more and 30% by weight or less. If the substrate concentration is too low, productivity may deteriorate. On the other hand, if the substrate concentration is too high, the coating of the silicon oxide film on the substrate may not proceed uniformly, and the effect of improving the photolytic activity may not be sufficiently obtained.

The concentration of silicon contained in the mixture is 0.05 to 5% by weight It is preferably 0.1% by weight or more and 3% by weight or less. If the silicon concentration is too low, the condensation of the silicate compound is delayed and the substrate may not be sufficiently covered with the silicon oxide film. If the silicon concentration is too high, the coating of the silicon oxide film on the substrate may not proceed uniformly.

[0049] In the production method of the present invention, the ratio of the amount of substrate and silicates having a photocatalytic activity, as the surface area 1 m ² per silicon atom of the substrate, 0. 0 1 mg / m ² or more, 0. It is preferably 5 mg / m ² or less. If the ratio is within this range, in the step of forming a silicon oxide film on the surface of the substrate, that is, an aqueous medium containing the substrate and a silicate, an aqueous medium containing a silicate, the substrate, and the substrate. A desired silicon oxide film can be formed on the surface of the substrate in the step of mixing and aging at least one of an aqueous medium containing silicate and an aqueous medium containing silicate. At the same time, since the amount of silicic acid, silicate ions, and / or oligomers thereof remaining unreacted without condensing on the surface of the substrate can be suppressed, a silicon oxide film having pores can be formed. Few. In the range of 0.5 mg / m ² or more and 5. Omg / m ² or less, as the ratio increases, the amount of unreacted substances increases and a silicon oxide film having pores may be formed. However, it is possible to avoid the formation of pores due to the progress of condensation of unreacted substances by shortening the treatment time.

[0050] If the silicon oxide film coating method of the present invention is shown more specifically, for example,

(Step a) Mixing at least one set selected from the group consisting of an aqueous medium containing a substrate and a silicate, an aqueous medium containing a silicate and a substrate, and an aqueous medium containing a substrate and an aqueous medium containing a silicate. The process of

(Step b) The step of aging this mixed solution and coating the substrate with a silicon oxide film,

(Step c) A step of separating and washing the photocatalyst coated with the silicon oxide film from the aqueous medium without neutralizing the mixed solution,

(Step d) comprising a step of drying and / or firing the photocatalyst coated with the silicon oxide film, and in steps a and b, both the substrate and the silicate The manufacturing method of maintaining the aqueous medium containing the pH at PH 5 or lower is mentioned.

[0051] When the photocatalyst coated with the silicon oxide film is separated from the aqueous medium, neutralization causes the following problems. That is, there are problems in that the efficiency of reducing the alkali metal content in the washing step is deteriorated, and that the silicon compound remaining dissolved in the aqueous medium is condensed and gelled to form a porous silica film. The problems described above are that the silicate solution should be dealt with in advance, and the dealued solution should be prepared and used for production, and the ratio of the substrate having photocatalytic activity and the amount of silicate used should be reduced. It is possible to avoid or minimize it. However, it is preferable to separate the photocatalyst coated with the silicon oxide film without neutralization from the aqueous medium because the above problems can be avoided and the production method is simple.

[0052] The method for separating the photocatalyst coated with the silicon oxide film from the mixed solution is not particularly limited. For example, known methods such as natural filtration, vacuum filtration, pressure filtration, and centrifugal separation can be suitably used. .

The method for cleaning the photocatalyst coated with the silicon oxide film is not particularly limited. For example, redispersion in pure water and repeated filtration, desalting and washing by ion exchange treatment, and repeated decantation can be suitably used. Also, depending on the use of the photocatalyst coated with a silicon oxide film, the cleaning step can be omitted.

[0053] The drying method of the photocatalyst coated with the silicon oxide film is not particularly limited, and for example, air drying, reduced pressure drying, heat drying, spray drying, and the like can be suitably used. Also, depending on the use of the photocatalyst coated with a silicon oxide film, the drying step can be omitted.

[0054] The method for firing the photocatalyst coated with the silicon oxide film is not particularly limited, and, for example, reduced-pressure firing, air firing, nitrogen firing and the like can be suitably used. Usually, firing can be carried out at a temperature of 200 ° C. or more and 120 ° C. or less, but preferably 400 ° C. or more and 100 ° C. or less, preferably 400 ° C. or more and 80 ° C. or more. C or less is more preferable. If the firing temperature is too low, a desired fired silicon oxide film may not be formed on the substrate surface, and sufficient photolytic activity may not be obtained. If the firing temperature is too high, sintering of the photocatalyst coated with the silicon oxide film may proceed too much, and sufficient photolysis activity may not be obtained. The

[0055] The water content contained in the photocatalyst coated with the silicon oxide film is preferably 7% by weight or less. 5% by weight or less is more preferable, and 4% by weight or less is most preferable. If the water content is too high, there is a possibility that a large amount of water is present around the silicon oxide, so that the gas adsorption performance is not sufficiently exhibited, and at the same time, sufficient photolytic activity cannot be obtained.

[0056] The photocatalyst coated with the silicon oxide film thus obtained can adsorb both acidic gas such as acetic acid, basic gas such as ammonia, and nonpolar gas such as toluene, and has excellent photocatalytic performance. Yes.

[0057] As described above, in the method for producing a photocatalyst coated with a silicon oxide film of the present invention, in order to obtain a silicon oxide film having no pores, the pH is lowered, the concentration of silicate, It is important to appropriately select the conditions such as the concentration of the substrate, the acidic solution to be used, the firing temperature after film formation, and the firing time.

In the present invention, the “compound containing phosphorus and calcium” is a compound containing phosphorus and calcium as its constituent substances. The shape, structure, composition, production method, etc. are not limited, but as an example of a compound containing phosphorus and calcium, apatite can be mentioned. Apatite is known as a general term for a group of minerals with a composition of M _{1 0} (Z 0 ₄ ) ₆ X ₂ , and the main components of M and Z are generally calcium and phosphorus, respectively. Known to. X is selected from the group consisting of F, C l, OH, and C 0 ₃ —or more. Here, it is known that the aperture usually has a hexagonal columnar shape, a plate shape, or the like.

[0059] The "compound containing phosphorus and calcium" indicates that the photocatalyst contains phosphorus and calcium, and the containing form, the content, and the preparation method are not particularly limited.

[0060] The phosphorus content and calcium content contained in the photocatalyst of the present invention are as follows. The phosphorus content is preferably 0.1% by weight or more and 10% by weight or less, more preferably 1% by weight or more and 10% by weight or ⁰ / o based on the total weight of the photocatalyst. It is as follows. The calcium content is preferably 0.2% by weight or more and 20% by weight or less, more preferably 2% by weight or more and 20% by weight or less, based on the total weight of the photocatalyst. If the phosphorus content or calcium content is too small, the coating amount of the compound containing phosphorus and calcium on the substrate having photocatalytic activity is not sufficient, and the protective effect of the organic substrate is not sufficiently exhibited. On the other hand, if the phosphorus content or the strength lucum content is too high, the coating amount of the compound containing phosphorus and the strength lucum on the substrate having photocatalytic activity is too large, and the ultraviolet light reaches the substrate having sufficient photocatalytic activity. Disappear. As a result, the photocatalytic activity is significantly reduced.

In the present invention, the step of producing a compound containing phosphorus and calcium is not particularly limited, but a compound containing phosphorus and calcium is produced and immobilized on a photocatalyst coated with a silicon oxide film produced in advance. The method is the simplest and most effective method.

[0062] The method for producing a compound containing phosphorus and calcium and immobilizing the compound as a fixed product on the photocatalyst coated with a silicon oxide film is not particularly limited, but a method for producing a protein can be applied. It is. In the production of the powder candy, there are a precipitation method, a wet method, a hydrothermal method, a mechanochemical method, etc., but a precipitation method characterized by precipitation in a simulated body fluid is most desirable.

[0063] The simulated body fluid used in the present invention includes N a CI, N a H C0 ₃ , N a ₂ H P0 ₄ , N a H ₂ P0 ₄ , KC I, KH C0 ₃ , K ₂ H P0 ₄ , KH the _{_{_{2 P0 4, Mg CI 2,}}} C a CI 2, N a 2 S0 4, and N a F any compound selected from like by dissolving in water, can be prepared. However, it is essential to add a compound containing calcium and a compound containing phosphorus. If necessary, HCI, (CH ₂ OH) ₃ CN H ₂ or the like can be added.

[0064] In the preparation of the simulated body fluid, the compound may be prepared in a single simulated body fluid, or a solution containing each compound is prepared separately and added as appropriate, and finally, You may prepare so that it may become a simulated body fluid. For example, prepare a solution containing calcium and a solution containing phosphorus separately, and then mix the two solutions A method of finally preparing a simulated body fluid can be performed.

[0065] The order in which the photocatalyst coated with a silicon oxide film is added to the simulated body fluid is not particularly limited. After preparing the simulated body fluid, a photocatalyst coated with a silicon oxide film may be added, or after adding a photocatalyst coated with a silicon oxide film to a solution containing calcium, a solution containing phosphorus may be added. Alternatively, a solution containing calcium may be added after adding a photocatalyst coated with a silicon oxide film to a solution containing phosphorus. Any order can produce the desired photocatalyst

[0066] The composition of the simulated body fluid used in the present invention, N a +: 1 20~1 60mM , K +: 1~20mM, C a 2+: 0. 5~50mM, M g 2+: 0. 5~ 50mM, CI _: 80~200mM, H CO 3 _: 0. 5~30mM, H P0 4 2 _: "! ~ 20mM, S0 4 2 -: 0."! ˜20 mM, F—: 0 to 5 mM, are preferable. If these concentrations are too low, the formation of calcium phosphate can take a long time. Also, if these concentrations are too high, calcium phosphate formation may occur rapidly, making it difficult to control the porosity and film thickness.

[0067] There is no particular limitation on the immersion time for mixing and holding the simulated body fluid and the photocatalyst coated with the silicon oxide film, but it is preferably 1 second to 10 days, more preferably 1 minute to 5 days.

[0068] The immersion temperature when mixing and holding the simulated body fluid and the photocatalyst coated with the silicon oxide film is not particularly limited, but is preferably 0 ° C or higher and 100 ° C or lower, and 30 ° C or higher and 80 ° C or higher. The following is more preferable. If the temperature is too low, it may take a long time to produce a compound composed of phosphorus and calcium. If the temperature is too high, it may be difficult to control the production of a compound composed of phosphorus and calcium due to evaporation of the simulated body fluid. is there.

[0069] The above-described production method can produce a photocatalyst containing a compound containing phosphorus and calcium as an immobilized product. This photocatalyst can be subjected to desired post-treatments such as a heat treatment step and a surface treatment step depending on the application. In the heat treatment, the compound containing phosphorus and calcium is immobilized, and from the viewpoint of crystallization, 50 It is desirable to carry out at a temperature of 750C to 700 ° C.

[0070] In the photocatalyst of the present invention, the immobilized product containing the compound containing phosphorus and calcium exhibits an effect as an adsorbent or a spacer. Such a photocatalyst is excellent in adsorption performance and hardly deteriorates an organic base material (a base material made of an organic substance such as a resin). Here, “deterioration of the organic base material” means that when the photocatalyst is added to the organic base material, the organic base material is decomposed and deteriorated by the decomposing power of the photocatalyst. The spacer effect of the immobilized substance in the photocatalyst is due to the structure in which the titanium oxide particles do not directly contact the organic base material. Therefore, it is difficult for the organic base material to be decomposed while maintaining the decomposing power of the photocatalyst.

[0071] The immobilization product containing the phosphorus- and calcium-containing compound of the present invention is not particularly limited as long as it has an effect as a spacer. <The titanium oxide particles are organic. Any structure that can prevent direct contact with the substrate is acceptable. For example, the photocatalyst of the present invention includes the above-described immobilized product that is immobilized on the surface thereof by a method such as the above-described precipitation. The immobilized product contains a compound containing phosphorus and calcium and is located on the surface of the silicon oxide film and / or on the surface of the substrate not covered with the silicon oxide film, and is immobilized on the surface. It shall mean. Examples of the shape of the immobilization material include protrusions such as rods, needles, and cones, membranes, and surface layers. The immobilization product has a smaller shape than the substrate. Further preferably, the immobilization product of the compound containing phosphorus and calcium is thicker than the thickness of the silicon oxide film formed on the substrate or has a shape protruding from the surface of the photocatalyst.

[0072] The photocatalyst according to the present invention can be used for the following applications, for example. However, the described use is an applicable example, and does not limit the present invention.

Antibacterial purposes include: car seats, seat covers, force—pets, handles, handle covers, shift knobs, dash pods, room lamps, train straps, net racks, linings, instrument panels, Door knob, inner wall, floor, ceiling, flooring such as indoor flooring, tatami mats, blinds, mouth scrub Furniture, decorative panels, blinds, bathroom components, handrails, tablecloths, wallpaper, wall materials, rock wool and other ceiling materials, bran, shoji, refrigerators, cookers, hand dryers, personal computers, mice, keyboards, etc. Electric appliances, glasses members, artificial foliage plants, medical equipment, fluorescent lamp covers for lighting equipment, sealing materials, plastering materials such as building rubber, curtains, cloth, clothing, bedding, rugs, upholstery, goodwill, yarn, Textile products such as cloth, ropes, nets, non-woven fabrics, outerwear, pants, shirts, socks and other clothing, sheets, futons, blankets and other beddings, tenacity, sheet covers, handkerchiefs, towels, calligraphy paper, shoji paper Newspaper paper, non-coated printing paper (advanced printing paper, intermediate printing paper, lower printing paper, thin leaf printing paper), coated printing paper (art paper, coated paper, lightweight coat) ), Special printing paper (color fine paper, other special printing paper), information paper (copy paper, carbonless paper, etc.), packaging paper (unbleached wrapping paper, bleached wrapping paper), sanitary paper (tissue paper, dust paper) Etc.), hybrid paper (industrial hybrid paper, household hybrid paper), etc.

For anti-fouling purposes, it can be applied as a lamp cover for automobiles, trains, motorcycle meters, helmet shields, and exterior sizing materials.

[0073] For the above applications, the organic material may contain a photocatalyst directly. At that time, a masterbatch containing a photocatalyst with a high concentration may be produced and then applied to a desired resin. Or after mixing photocatalyst with paint such as phenol resin, vinyl resin, epoxy resin, paint, ink, coating agent, wallpaper surface finishing agent, ceiling building material finishing agent, etc. A layer may be coated.

[0074] Further, the photocatalyst according to the present invention can be used in the form of a dispersion or a coating composition, if necessary. Furthermore, high activation, imparting visible light response, compounding with antibacterial metal compounds, imparting dispersibility by surface modification, or suppressing degradation of photocatalyst-containing materials by compounding with compounds that are inactive as photocatalysts, etc. It can also be used as a raw material for photocatalyst improvement methods.

[0075] The photocatalyst dispersion liquid containing the photocatalyst according to the present invention includes the photocatalyst and the liquid medium according to the present invention. Body, and a dispersion stabilizer. The method of using this dispersion liquid is not particularly limited, but it may be used after being mixed with a base material to which a photocatalytic function is to be imparted, or may be applied to the surface of the base material and optionally dried. And / or after firing. Alternatively, it can be used after spraying on the substrate in a spray form. The target base materials can be used for ceramics, glass, film, wallpaper, building materials, timber, clothing, ceiling materials, tableware, etc. Since the photocatalyst according to the present invention can protect the organic base material, the wallpaper, curtain, clothing, nonwoven fabric, cloth, film, organic paint, organic interior material, organic building material mainly composed of an organic polymer In addition, it is desirable to use it for textile products, etc. in that the effect of the present invention is exhibited. It can also be used as a raw material for photocatalyst-containing materials and photocatalyst coating compositions.

[0076] Examples of the liquid medium include water, alcohols such as methyl alcohol and ethyl alcohol, aromatics such as benzene, toluene and xylene, esters such as ethyl acetate, and ketones such as acetone. These can be suitably used alone or in combination of two or more according to the application. However, it is more desirable to use water from the viewpoint of environmental harmony.

[0077] As the dispersion stabilizer, ionic surfactants, wetting agents, thickeners, acids, bases and the like can be suitably used. Among these dispersion stabilizers, one kind may be contained, or two or more kinds may be contained. From the viewpoint of dispersibility, the surfactant is preferably an ionic surfactant such as a carbonate, a sulfonate, a sulfate ester salt, a phosphate ester salt, an alkylamine salt, or a quaternary ammonium salt. .

[0078] The concentration of the photocatalyst contained in the photocatalyst dispersion liquid is not particularly limited, but it is preferably 2% by weight or more and 50% by weight or less with respect to the entire photocatalyst dispersion liquid. More preferably, it is 30% by weight or less. If the concentration of the photocatalyst is too low, the concentration of the photocatalyst contained in the dispersion may decrease and the economic efficiency may deteriorate. If the concentration of the photocatalyst is too high, the dispersibility of the photocatalyst contained in the dispersion may deteriorate. [0079] The concentration of the dispersion stabilizer contained in the photocatalyst dispersion liquid is not particularly limited, but the total amount of the dispersion stabilizer is desirably 1% by weight or more and 100% by weight or less based on the photocatalyst. It is more desirable that it be 2 wt% or more and 200 wt% or less. If the concentration of the dispersion stabilizer is too low, the dispersion of the photocatalyst by the dispersion stabilizer may not proceed sufficiently. If the concentration of the dispersion stabilizer is too high, the active ingredient exhibiting a photocatalytic action may be reduced when the dispersion is actually used.

[0080] When dispersing the photocatalyst according to the present invention, the equipment to be used is not particularly limited. Force Wet dispersion equipment such as a pole mill pulverizer, a bead mill pulverizer, an ultrasonic pulverizer, and a high-pressure wet atomizer can be suitably used. It is. When dispersing, these wet dispersion devices may be used alone or a plurality of devices may be used in succession. In addition, before the dispersion by the wet pulverizer, coarse pulverization may be performed by a pulverizer such as a dry pulverizer.

[0081] The photocatalyst coating composition containing the photocatalyst according to the present invention includes the photocatalyst according to the present invention, a liquid medium, and a binder. The method of using this photocatalyst coating composition is not particularly limited, but it may be used after being applied to the surface of a base material to which a photocatalytic function is to be imparted and subjected to any drying and / or baking treatment. At this time, it may be applied directly to the target substrate, or it may be applied after coating one or more intermediate layers to improve adhesion or protect the substrate. I do not care. Alternatively, it can be used after spraying on the substrate. As the target substrate, the same ones as described above can be used. However, since the photocatalyst according to the present invention can protect the organic base material, the effect of the present invention can be exerted mainly by using it for a product made of an organic polymer as exemplified above. This is desirable.

[0082] As the liquid medium, for example, the same ones as those used in the photocatalyst dispersion liquid exemplified above can be used. These can be suitably used singly or in combination of two or more according to the application. However, from the viewpoint of environmental harmony, it is preferable to use water as the liquid medium.

[0083] Examples of the binder include colloidal silica, silicone resin, and alkoxy. Silane, and its partial hydrolysates, organoalkoxysilanes, which are alkoxysilanes partially substituted with hydrocarbon groups, silicon compounds such as orthotitanic acid, titanium peroxide, titanium alkoxide, titanium acetylylacetonate, titanium oxide Titanium compounds such as sol, organic polymers such as acrylic, urethane, and fluororesin may be used singly or in combination of two or more. In addition, a block polymer body or a gradient polymer having two or more types of partial structures in one molecule can be used. Of these, titanium compounds, silicon compounds, and fluororesins are preferred because they are hardly decomposable. In particular, a titanium compound and a silicon compound are preferable because restrictions on heat treatment after coating are not severe. Particularly, from the viewpoint of environmental harmony, colloidal silica, orthotitanic acid, titanium peroxide, and titanium oxide sol, which are completely composed of inorganic substances, are more preferable.

[0084] The photocatalyst coating composition according to the present invention is not particularly limited in the production method, and any method may be used as long as it is a wet treatment method having a dispersion or grinding effect. In addition, the constituent components may be mixed and then subjected to dispersion, pulverization treatment, or stepwise treatment. Further, a method of mixing a binder with the photocatalyst dispersion can also be used.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the following, an uncoated photocatalyst, a photocatalyst coated with a silicon oxide film, and a photocatalyst containing a compound composed of phosphorus and calcium are all referred to as “photocatalyst”.

[0086] First, the evaluation method used in the examples will be described. Here, unless otherwise indicated, the phosphorus content and calcium content are expressed in weight% based on the whole photocatalyst.

(i) Calcium content

The calcium content was quantified using a fluorescent X-ray analysis method (LAB CENTR XR E-1700, Shimadzu Corporation).

(ii) Phosphorus content The phosphorus content was quantified using a fluorescent X-ray analysis method (LAB CENTER XRE— 1700, Shimadzu Corporation).

(i i i) Silicon content

The silicon content was quantified using X-ray fluorescence analysis (LAB CENTER XRE— 1700, Shimadzu Corporation).

(iv) Specific surface area

The specific surface area was measured by a BET method specific surface area measuring device.

(Example 1)

Water 200 g and 1 N aqueous hydrochloric acid 66. 9 g was added to a glass flask, titanium dioxide (S T_01, Ishihara Sangyo Co., adsorbed water content 9 wt%, specific surface area by BET method specific surface area measuring apparatus 300m ² / g) 24.5 g was dispersed to prepare Liquid A. Beaker one in water 1 00 g of water glass No. 1 (S i O ₂ content of 35 to 3 8 wt ^{_{0/0, JIS- K 1 408}} ) 1 0. 7 g was added and the stirred solution B. Liquid A was maintained at 35 ° C and stirred while liquid B was added dropwise at 2 ml / min to obtain liquid mixture C. The pH of mixture C at this time was 2.3. Stirring was continued for 3 days while maintaining the mixture C at 35 ° C. Thereafter, the mixture C was subjected to pressure reduction filtration, and the obtained residue was washed by repeating redispersion in 50 mL of water and filtration under reduced pressure four times, and then allowed to stand at room temperature for 2 days. The obtained solid was pulverized in a mortar and then subjected to a baking treatment at 600 ° C. for 3 hours to obtain photocatalyst 1. The photocatalyst 1 had a phosphorus content of 0.05% by weight or less, a calcium content of 0.05% by weight or less, and a silicon content of 6.9% by weight. The specific surface area of this photocatalyst 1 was 212.8 m ² / g. Therefore, the amount of silicon supported per 1 m ² of the surface area of the photocatalyst 1 was 0.32 mg.

The results of measuring the pore distribution of this photocatalyst 1 are shown in FIG.

Then, as a pseudo body fluid, N a CI, N a HC0 3, KC I, K 2 HP 0 4 ■ 3 H 2 0, and _{_{M g CI 2 ■ 6 H 2}} O Ca CI 2, N a 2 S0 4, HC I, and _{_{(CH 2 OH) 3 CN H}} 2, using distilled water, N a +: 1 47mM, K +: 5mM, C a 2+: 2. 5mM, M g 2 +: 1. 5mM, C l _: 1 47mM, HC0 ₃ _ : 4.2 mM, HP 0 ₄ ² _: 1. OmM, S 0 ₄ ² _: 0.5 mM Prepare an aqueous solution, add Photocatalyst 1 to it, and leave it at 50 ° C for 14 days did. After standing, it was filtered and heat-treated at 100 ° C for 3 hours to obtain photocatalyst 2. Phosphorus content of this photocatalyst 2 was 0.8% by weight, calcium content was 1.8% by weight The silicon content was 6.5% by weight. Further, the specific surface area of the photocatalyst 2 was measured by a BET specific surface area measuring apparatus, and found to be 199.1 m ² / g. Therefore, silicon supported amount per surface area of 1 m ² of photocatalytic 2 0. 33 mg der ivy.

(Example 2)

[0088] As the simulated body fluid, N a CI, N a H C0 3, KC I, and _{_{K 2 H P0 4 ■ 3 H}} 2 0, M g CI 2 ■ 6 H 2 OC a CI 2, N a 2 S0 4 , HCI, (CH ₂ 0 H) 3 CNH ₂ and distilled water, N a +: 1 47 mM, K +: 5 mM, C a ^{2 +} : 7.5 mM, Mg ²⁺ : 1.5 mM, CI " : 1 47 mM, H C0 ₃ _: 4.2 mM, HP 0 ₄ ² _: 1 5. OmM, SO ₄ ² _: 0.5 mM of aqueous solution was prepared, and Photocatalyst 1 was added to it. It was left for 14 days at 50 ° C. After standing, it was filtered and subjected to heat treatment at 100 ° C. for 3 hours to obtain photocatalyst 3.

The photocatalyst 3 had a phosphorus content of 1.7% by weight, a calcium content of 3.9% by weight, and a silicon content of 6.1% by weight. Further, the specific surface area of the photocatalyst 3 was measured by a BET specific surface area measuring apparatus, and found to be 207.0 m ² / g. Therefore, the amount of silicon supported per 1 m ² of the surface area of the photocatalyst 3 was 0.29 mg.

[0089] [Comparative Example 1]

Titanium dioxide (S T_0 1, Ishihara Sangyo Co., adsorbed water content 9 wt%, a specific surface area of 300 m ² / g) and, in the air, and the photocatalyst 4 was dried at 200 ° C. The photocatalyst 4 had a phosphorus content of 0.05% by weight or less, a calcium content of 0.05% by weight or less, and a silicon content of 0.0% by weight. Further, when the specific surface area of this photocatalyst 4 was measured with a BET specific surface area measuring device, 2 1 4. 3 m ² / g. Therefore, the amount of silicon supported per 1 m ² of the surface area of the photocatalyst 4 was 0. Omg.

[0090] [Comparative Example 2]

As simulated body fluids, N a CI, N a H C0 ₃ , KC I, K ₂ H P0 ₄ ■ 3 H ₂ 0, Mg CI ₂ ■ 6 H ₂ OC a CI ₂ and N a ₂ S0 ₄ , HCI, and _{(CH 2 0 H) 3 CNH} 2, using distilled water, N a +: 1 47mM, K +: 5mM, C a 2 +: 2. 5mM, M g 2 +: 1. 5mM, C l _: 1 47 mM, H C0 ₃ _: 4.2 mM, HP 0 ₄ ² _: 1. OmM, S 0 ₄ ² _: 0.5 mM Prepare an aqueous solution, and add photocatalyst 4 to it. And left at 50 ° C for 14 days. After standing, it was filtered and heat-treated at 100 ° C for 3 hours to obtain photocatalyst 5.

The photocatalyst 5 had a phosphorus content of 1.9% by weight, a calcium content of 4.3% by weight, and a silicon content of 0.0% by weight. In addition, as a result of the specific surface area of the photocatalyst 5 was measured by a BET method specific surface area measuring apparatus, 1 88. 2m ² / g der ivy. Therefore, the amount of silicon supported per 1 m ² of the surface area of the photocatalyst 5 was 0.0 mg.

[0091] (Preparation of photocatalyst sample plate for photolysis activity evaluation)

In a 10 Om L polyethylene jar, 5.0 g of photocatalyst 2 and glass beads with a diameter of 1 mm 50. O g, ethanol 44. O g, 1 N hydrochloric acid 0.5 g, and a surfactant ( Triton X_1 00, Union ■ Rikiichi Baid Co., Ltd.) 0.5 g was added and sealed. This was put into a stainless steel pole mill pot with an internal volume of 300 mL, and cloth was packed in the gap so that the wide-mouthed bottle was in the center of the pole mill pot. After sealing the pole mill pot, it was placed on a pole mill turntable and dispersed for 18 hours at a speed of 60 revolutions per minute. After the treatment, the wide-mouth bottle was taken out, and the glass beads were filtered with a nylon mesh sheet to obtain an ethanol dispersion A of photocatalyst 2. Next, the slide glass (2.6 cm X 7.6 cm, thickness 1 mm) whose weight was measured in advance was immersed in the ethanol dispersion A of the photocatalyst 2 and pulled up. Every 90 seconds, two-thirds of the slide glass was submerged 12 times at a speed of 0.4 cm per second. Thereafter, the slide glass was dried at room temperature. Next, the photocatalyst 2 adhering to the other surface was removed by rubbing with a glass plate except for one side of the slide glass of 2.6 cm × 7.6 cm (one surface of the slide glass).

Furthermore, a photocatalyst sample plate A was produced by subjecting the slide glass to firing at 400 ° C for 3 hours in an air atmosphere in an electric furnace.

When weighed before and after immobilization of photocatalyst, and measured the length and dimension of the part where photocatalyst 2 was immobilized, photocatalyst 2 applied weight was 6. Omg, coated area was 11.8 cm ² , per area The coating weight was 5.1 g / m ² .

[0092] Photocatalyst sample plate B was prepared in the same manner as described above except that photocatalyst 3 was used instead of photocatalyst 2 and dipping and pulling were performed once. When weighed before and after immobilization of photocatalyst, and measured the length of the part where photocatalyst 3 was immobilized, photocatalyst 3 applied weight was 5.9 mg, coated area was 11.7 cm ² , per area The coating weight was 5. O g / m ² .

[0093] Photocatalyst sample plate C was produced in the same manner as described above except that photocatalyst 4 was used instead of photocatalyst 2 and dipping and lifting were performed only once. When weighed before and after photocatalyst immobilization, and measured the length of the part where photocatalyst 4 was immobilized, photocatalyst 4 applied weight was 5.9 mg, application area was 11.8 cm ² , per area coating weight was 5. O g / m ^2.

[0094] Photocatalyst sample plate D was prepared in the same manner as described above except that photocatalyst 5 was used instead of photocatalyst 2 and dipping and lifting were performed only once. When weighed before and after photocatalyst immobilization, and measured the length of the photocatalyst 5 immobilization part, the photocatalyst 5 applied weight was 5.8 mg, the application area was 11.8 cm ² , per area The coating weight was 4.9 g / m ² .

[0095] Photocatalyst sample plate E was produced in the same manner as described above except that photocatalyst 1 was used instead of photocatalyst 2 and dipping and lifting were performed only once. When weighed before and after immobilization of photocatalyst, and measured the length of the part where photocatalyst 1 was immobilized, photocatalyst 1 applied weight was 5.9 mg, coated area was 11.7 cm ² , per area The coating weight was 5. O g / m ² . [0096] (Acetaldehyde photolysis test)

Photocatalyst sample plates A, B, C, D, and 作製 prepared in the above (Preparation of photocatalyst sample plate) were irradiated with ultraviolet rays of 5.4 mW / cm ² for 3 hours in an air atmosphere. A 27W black light bull light (Sankyo Electric, FPL 27 BLB) was used as the light source, and UVA-365 (manufactured by Custom Corp.) was used for the UV intensity measurement. Then, prepare three 1-liter Tedlar (DuPont registered trademark) bags with one silicone packing connector and one minicock, cut one side of the Tedlar (DuPont registered trademark) bag, Each of the photocatalyst sample plates A to C which had been previously irradiated with ultraviolet rays was placed and attached to the center of the bag with a 5 mm square double-sided tape. And it was sealed with a hitler. Subsequently, the internal air was extracted from the mini-cock using a vacuum pump, the cock was closed, and left in the dark overnight.

[0097] Next, a wet mixed gas in which a mixed gas of 20% oxygen and 80% nitrogen was immersed in 15 ° C ion-exchange water and a mixed gas of 1% acetoaldehyde / nitrogen were mixed. A gas with a cetaldehyde concentration of 101 ppm was prepared. 600 mL of this gas was sampled and injected into a bag containing a photocatalyst sample plate, and then the bag was left in the dark for 20 hours. After that, the cetaldehyde concentration and carbon dioxide concentration of the gas inside the bag were measured. A gas chromatograph with a methanizer (Shimadzu Corporation, GC—14) was used for concentration measurement. After the analysis, the photocatalyst sample plate stored in the bag was irradiated with light using a full-white fluorescent lamp (Matsushita Electric Works, 1 OW, FL 1 ON), and the gas inside the bag was irradiated every 2 hours. Analysis was carried out. At this time, the surface of the photocatalyst sample plate on which the photocatalyst was immobilized was placed at a distance of 4 cm from the fluorescent lamp. The UV intensity measured at the same place with the same film as the bag as the filter was 1 1 W / cm ² .

[0098] Figure 2-A shows the change over time in the concentration of acetonitrile in the gas inside the bag. Figure 2_B shows the change over time in the carbon dioxide concentration in the gas inside the bag.

[0099] (Preparation of sample plate for organic substrate deterioration evaluation) In a 10 Om I polyethylene jar, 5 g of photocatalyst 2, 50 g of glass pole with a diameter of 1 mm, and 45 g of ethanol were added in this order and sealed. This was put into a stainless steel pole mill pot with an internal volume of 30 Om L, and cloth was packed in the gap so that the wide-mouthed bottle was in the center of the pole mill pot. After sealing the pole mill pot, it was placed on a pole mill turntable and dispersed for 18 hours at a speed of 60 revolutions per minute. After the treatment, the wide-mouth bottle was taken out, and the glass beads were filtered off with a nylon mesh sheet to obtain a photocatalyst 2 ethanol dispersion. In a 10 Om I glass beaker, 5 g of polyacrylic acid 25000 (average molecular weight: 25000) and 45 g of ethanol were added, followed by stirring with a stirrer for 30 minutes to obtain a polyacrylic acid solution.

The ethanol dispersion of photocatalyst 2 and the polyacrylic acid solution were mixed in equal amounts, and stirred for 30 minutes to obtain a photocatalyst-polyacrylic acid coating solution. Next, a slide glass (2. 6 cm x 7.6 cm, 1 mm thick) photocatalyst-polyacrylic acid coating solution was immersed and pulled up. Every 90 seconds, two-thirds of the slide glass was submerged 12 times at a speed of 0.4 cm per second.

The slide glass is then air-dried at room temperature, and then the photocatalyst and polyacrylic adhering to the other side of the slide glass is removed except for one side of the slide glass (2.6 cm x 7.6 cm). The acid was removed by rubbing with a glass plate to obtain a photocatalyst sample plate F. When the weight was measured before and after the photocatalyst immobilization, the total coating weight of the photocatalyst 2 and polyacrylic acid was 0.8 1 mg.

[0100] Photocatalyst sample plate G was prepared in the same manner as described above except that photocatalyst 3 was used instead of photocatalyst 2, and dipping and lifting were performed only once. When the weight was measured before and after immobilization of photocatalyst, the total coating weight of photocatalyst 3 and polyacrylic acid was 0.79 mg.

[0101] Photocatalyst sample plate H was prepared in the same manner as described above except that photocatalyst 4 was used instead of photocatalyst 2 and dipping and lifting were performed only once. Before and after photocatalyst immobilization When the weight was measured, the total coating weight of the photocatalyst 4 and polyacrylic acid was 0.84 mg.

[0102] Photocatalyst sample plate I was prepared in the same manner as described above except that photocatalyst 5 was used instead of photocatalyst 2 and dipping and lifting were performed only once. When the weight was measured before and after immobilization of the photocatalyst, the total coating weight of photocatalyst 5 and polyacrylic acid was 0.78 mg.

[0103] Photocatalyst sample plate J was prepared in the same manner as described above, except that photocatalyst 1 was used instead of photocatalyst 2, and dipping and lifting were performed only once. When the weight was measured before and after immobilization of the photocatalyst, the total coating weight of photocatalyst 1 and polyacrylic acid was 0.83 mg.

[0104] (Organic substrate degradation inhibitory evaluation test)

The photocatalyst sample plates F, G, H, I, and J prepared in the above (preparation of organic substrate deterioration evaluation sample plate) were irradiated with ultraviolet rays of 4. OmW / cm ² for a predetermined time in an air atmosphere. A 27 W black light bull light (Sankyo Electric, FP L 27 B LB) was used as the light source, and UVA-365 (manufactured by Custom Corp.) was used for the ultraviolet intensity measurement.

For each photocatalyst sample plate, the change in coating weight before and after UV irradiation was weighed.

Figure 3 shows the change in coating weight over time.

From FIG. 2 _A and FIG. 2 _B, the photocatalysts 2 and 3 which are the photocatalysts of the present invention showed excellent photocatalytic activity. Here, the photocatalyst 5 having no silicon oxide film showed no significant change in the acetonitrile concentration and the co ₂ production concentration even after 8 hours. Therefore, photocatalyst 5 was inferior in photocatalytic activity. In addition, as a result of evaluating the ability to suppress deterioration of the organic base material, as shown in FIG. 3, the photocatalysts 2 and 3 have a weight residual ratio of 60% or more even after 12 hours of ultraviolet irradiation, that is, 20% of polyacrylic acid. % Or more remained, and was found to have excellent ability to suppress deterioration of the organic base material. Here, the mixing ratio of the photocatalyst and polyacrylic acid was 1: 1, and the weight residual ratio of 50% indicates that the entire amount of polyacrylic acid was photolyzed. On the other hand, when photocatalyst 1 or 4 is used, weight remaining after 12 hours The rate was 50% or less, that is, polyacrylic acid was completely decomposed and was inferior in suppressing deterioration of the organic base material.

From the above results, the photocatalyst of the present invention was excellent in the balance of both the photocatalytic activity and the organic substrate suppressing effect.

Claims

The scope of the claims

[1] a substrate having photocatalytic activity;

A silicon oxide film covering the substrate;

Further including compounds containing phosphorus and calcium,

A photocatalyst characterized by satisfying the following conditions (a) and (b):

(a) The phosphorus content is 0.1 wt% or more and 10 wt% or less.

(b) calcium content of 0.2 wt% or more, 20 weight ^_0/0 or less.

[2] The compound containing phosphorus and calcium is located on the surface of the silicon oxide film and / or on the surface of the substrate not covered with the silicon oxide film as an immobilization product containing the compound. The photocatalyst according to claim 1.

[3] The photocatalyst according to claim 2, wherein the silicon oxide film is a fired film.

[4] The photocatalyst according to claim 3, wherein the fired film is a fired film fired at 400 ° C or higher.

[5] The photocatalyst according to claim 4, wherein the silicon oxide film has no pores in a pore size distribution measurement in a 20 to 500 angstrom region by a nitrogen adsorption method.

[6] The amount of silicon supported per 1 m ² of the surface area of the substrate having the silicon oxide film is 0.

The photocatalyst according to claim 5, which is 10 mg or more and 2. Omg or less.

7. The photocatalyst according to claim 6, wherein the substrate is an anatase type, a rutile type, or titanium oxide containing a mixture thereof.

8. The photocatalyst according to claim 7, wherein the substrate is a particle.

[9] The method for producing a photocatalyst according to claim 1, comprising the following steps:

(C) Firing the photocatalyst obtained in step (B) above 400 ° C Process,

(D) forming an immobilized product containing a compound containing phosphorus and calcium on the surface of the photocatalyst obtained in the step (C) using an aqueous solution of a compound containing phosphorus and a compound containing calcium;

(E) separating the photocatalyst obtained in the step (D) from the aqueous solution,

10. The method for producing a photocatalyst according to claim 9, wherein in the step (C), the photocatalyst obtained in the step (B) is dried and then calcined.

11. The method for producing a photocatalyst according to claim 10, wherein in the step (C), the photocatalyst obtained in the step (B) is calcined at 1 200 ° C. or lower.

As the aqueous solution of the compound compounds and containing calcium containing [12] phosphorus, N a CI, N a HC0 3, N a 2 H P0 4, N a H 2 P0 4, KC I, KHC0 3, K 2 H P0 ₄ , at least one compound selected from the group consisting of KH ₂ P0 ₄ , Mg CI ₂ , Ca CI ₂ , Na ₂ S 0 ₄ , NaF, HC 1, and (CH ₂ OH) ₃ CN H ₂ The method for producing a photocatalyst according to claim 11, wherein a simulated body fluid dissolved in is used.

[13] The simulated body fluid is, N a +: 1 20~1 60mM , K +: 1~20mM, C a 2 +: 0. 5~50mM, Mg 2+: 0. 5~50mM, CI _: 80~200m _{M, H C0 3 -:!} . 0. 5~30mM, HP 0 4 2 _: "~ 20mM, S 0 4 2 _: 0 1~20mM, and F_: an aqueous solution containing 0-5 mM, claim 1. A method for producing a photocatalyst according to 2.

[14] A photocatalyst dispersion liquid comprising the photocatalyst according to claim 1, a liquid medium, and a dispersion stabilizer.

15. The photocatalyst dispersion liquid according to claim 14, wherein the liquid medium is water.

16. The photocatalyst according to claim 14, wherein the dispersion stabilizer is an ionic surfactant. Dispersion.

[1 7] A photocatalyst coating composition comprising the photocatalyst according to claim 1, a liquid medium, and a binder.

18. The photocatalytic coating composition according to claim 17, comprising a compound containing titanium or silicon as the binder.

[20] The photocatalyst coating composition according to claim 17, comprising water and / or alcohol as the liquid medium.