JP2782329B2 - Photocatalyst material and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photocatalyst material and a method for producing the same.

[0002]

2. Description of the Related Art Various types of odorous substances causing odor, unpleasant odor, and the like exist in a living space of a house, an office, a factory, and the like. For this reason, various fragrances,
Deodorization and deodorization are performed by activated carbon or the like. However, a fragrance requires replenishment of a chemical solution, and activated carbon has a relatively short life and is difficult to regenerate.

As a method for solving these problems, various methods have been proposed in which a photocatalytic substance such as titanium oxide is supported on various base materials and the malodorous substance is decomposed by utilizing the photocatalytic reaction. The method using an inorganic cured body as
Does not yet exist. Therefore, the present inventors have attempted to develop a photocatalyst material in which a photocatalyst substance is supported on an inorganic cured body.
However, when a photocatalytic material was produced by adding titanium oxide, which is a typical substance as a photocatalyst, to an inorganic cured product, it was found that there was a problem that the deodorizing effect was reduced with time.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a photocatalyst material which exhibits a good deodorizing effect over a long period of time.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems of the prior art, and as a result, when titanium oxide and a specific oxidation promoter are allowed to coexist in the inorganic cured product,
It was unexpectedly found that a material exhibiting an action of decomposing malodorous substances over a long period of time was obtained, and the present invention was completed.

That is, the present invention relates to a photocatalyst material characterized in that part or all of titanium oxide and an oxidation accelerator are present in the surface layer of an inorganic cured product.

Hereinafter, the present invention will be described in detail.

The inorganic cured material used for the photocatalyst material of the present invention is an inorganic curable composition having the property of being cured by hydration bonding, precipitation of crystals or carbonation after kneading with water, and by heating during wet molding. It refers to an inorganic curable composition having a curing property, or a cured product obtained from an inorganic curable composition having a property of being cured by drying or steam curing after wet molding.

[0009] Specifically, it is obtained from an inorganic curable composition containing at least one of cement, synthetic calcium silicate, synthetic magnesium silicate and magnesium carbonate, and is, for example, air-hardened cement, hydraulic cement or Inorganic hardened products which are hardened by hydration bonding, precipitation of crystals or carbonation after kneading the special cement with water, and inorganic hardened products obtained from magnesium carbonate, synthetic calcium silicate or synthetic magnesium silicate, and the like.

As the air-hardening cement, for example, gypsum,
Magnesia cement, lime and the like. The lime includes quick lime, slaked lime, lime plaster, lime mortar, dolomite plaster and the like, and the gypsum includes hemihydrate gypsum and gypsum plaster. The air-hardened cement can be used as a hardened material, for example, by kneading it with water or the like, followed by drying or the like, and hardening by hydration bonding, precipitation of crystals or carbonation. When a hardened gypsum is used, a hemihydrate gypsum is kneaded with water or the like, and then a hardened gypsum obtained by drying, or a hemihydrate gypsum or anhydrous gypsum obtained by further heating the hardened gypsum Cured bodies can also be used.

The hydraulic cement includes, for example, Portland cement, alumina cement, mixed cement and the like. Hydraulic cement is, for example, kneaded together with water and hardened body hardened by hydration bonding, concrete, slate, mortar and other cement products obtained by adding water, sand, etc. to hydraulic cement and kneading. It is included in the cured product of hydraulic cement.

[0012] As special cement, one of refractory cement
Hydraulic refractory mortar, which is a seed, is exemplified.

As magnesium carbonate, it is particularly preferable to use basic magnesium carbonate. The cured product mainly composed of basic magnesium carbonate is obtained by adding water to basic magnesium carbonate powder and, if necessary, adding and mixing auxiliary materials such as fibrous substances. A molded product obtained by heat treatment or a basic magnesium carbonate molded product obtained by heat treatment at the time of dehydration molding using a raw material slurry containing magnesium orthocarbonate can be used as an inorganic cured product. In these compacts, basic magnesium carbonate, normal magnesium carbonate and the like may be mixed.

Examples of the synthetic calcium silicate include those obtained by a hydrothermal reaction from a lime raw material and a silicic acid raw material, such as zonotolite, tobermorite, fosharite, gyrolite, α-dicalcium silicate, tricalcium silicate, and fillebrandite. Synthetic calcium silicate hydrates such as, rosenhanite, truscotite, lierite, calciochondrodite, kilcoanite, aphilite, quasicrystalline calcium silicate (CSHn),
Synthetic calcium silicates such as wollastonite obtained by heating synthetic calcium silicate hydrates such as the above-mentioned zonotlite and tobermorite are exemplified.

The inorganic cured product containing calcium silicate as a main component may be any one produced by any known method. For example, an aqueous slurry containing the above-mentioned calcium silicate is synthesized and obtained by drying after dehydration molding, or a raw material slurry composed of a lime raw material and a silicate raw material is added with a fibrous auxiliary raw material, which is formed into a paper and then steam cured. A molded article obtained by the above method can be used.

As the inorganic cured product mainly composed of synthetic magnesium silicate, known materials can be used. For example, JP-A-58-9812, JP-B-61-489 can be used.
No. 76 and the like are disclosed.

Among the above-mentioned inorganic curable compositions, those cured by dry molding, such as powders of synthetic calcium silicate, basic magnesium carbonate, etc., may be used as the above-mentioned inorganic cured material. it can.

Among these inorganic cured products, those obtained from an inorganic curable composition mainly containing at least one of synthetic calcium silicate, hydraulic cement, gypsum and basic magnesium carbonate are preferred. In addition, among these inorganic cured products, if a material having the property of adsorbing malodorous substances such as synthetic calcium silicate is used, malodorous substances can be effectively decomposed and removed, and particularly excellent. A deodorizing effect or the like can be obtained.

The type of titanium oxide is not particularly limited, and any known commercially available titanium oxide can be used as long as it acts as a catalyst in the presence of light to decompose malodorous substances. Examples of such titanium oxide include anatase-type TiO ₂ fine powder and rutile-type TiO ₂ fine powder. When titanium oxide is directly supported as a powder, the finer particles generally have a better deodorizing effect, but usually have a particle size of about 5 to 250 nm, preferably about 10 to 100 nm. Just use it.

The type of the oxidation promoter is not particularly limited as long as it has a function of promoting the catalytic action of titanium oxide, but at least one of a transition metal, a noble metal, a hydroxide of a rare earth element, a halide and a salt. It is preferable to use one kind. As the salts, inorganic salts such as sulfates, nitrates, phosphates and carbonates, and organic acid salts such as acetates can be used. Among these oxidation promoters, N
i, Cr, Fe, Zn, Ti, Mn, Co, Mo, V,
Sr, W, Pd, Au, Ag, Pt, La, Ce, P
It is more preferable to use at least one of hydroxides, halides and salts of r, Nd, Dy, Ho, Er and Lu. More specifically, iron sulfate Fe ₂ (SO ₄ ) ₃ ,
Silver nitrate AgNO _{3 and the} like.

Part or all of the titanium oxide and the oxidation accelerator are present in the surface layer of the cured inorganic material. This includes the case where the titanium oxide and the oxidation accelerator are present inside the surface layer of the cured product, as well as the case where they are present on the surface of the cured product. However, when the titanium oxide and the oxidation accelerator are present on the surface of the cured product, if the titanium oxide and the oxidation promoter are contained in a large amount, the titanium oxide and the oxidation promoter are likely to fall off and peel off. It is better to do.

Here, the surface layer of the cured product refers to a range in which titanium oxide and an oxidation accelerator capable of deodorizing are present, and the surface layer of the cured product is usually several meters from the surface of the cured product.
It refers to the part up to about m inside.

The contents of the titanium oxide and the oxidation promoter are as follows. That is, when the titanium oxide and the oxidation accelerator are present in the cured body surface layer, the titanium oxide and the oxidation accelerator are added to the total amount of the inorganic curable composition and the titanium oxide and the oxidation accelerator as described above. As long as the total amount does not exceed 95% by weight, titanium oxide is contained in an amount of 5% by weight or more, and an oxidation promoter is contained in an amount of 1% by weight or more (may be more than 100% by weight) with respect to the titanium oxide. Good.

When the titanium oxide and the oxidation accelerator are present on the surface of the molded product, the total amount of the titanium oxide and the oxidation accelerator is generally about 2 to 100 g / m ² , preferably 40 to 100 g / m ^2.
The amount may be 80 g / m ^2, and the amount of the oxidation promoter may be generally 1% by weight or more based on titanium oxide. The above content is 10
If it exceeds 0 g / m ² , desorption / peeling tends to occur.

As described above, according to the present invention, as long as the titanium oxide and the oxidation accelerator are contained in the cured body surface layer in a predetermined amount, either the titanium oxide and the oxidation accelerator may be contained in the cured body or not at all. But it is good.

In the photocatalyst material of the present invention, if necessary,
By further forming a surface protective layer on the surface of the material, it is possible to prevent the titanium oxide and the oxidation promoter present near the surface from falling off or peeling off while substantially maintaining the deodorizing effect. The material used for the surface protective layer is not particularly limited as long as it does not extremely reduce the deodorizing function of titanium oxide and the oxidation accelerator, but among them, inorganic oxides, resins and the like are preferable. SiO ₂ , Al ₂ O ₃ , Sb ₂ O ₃ , ZrO ₂ ,
It is desirable to use at least one of TiO ₂ , SnO ₂ , Fe ₂ O ₃ , CeO ₂ , WO ₃ and MoO ₃ , and a resin containing at least one of a fluorine resin and a silicone resin. When an inorganic oxide such as SiO ₂ is used, it is preferably used as a sol. In addition,
If necessary, these substances can contain calcium carbonate and the like.

In the photocatalyst material of the present invention, a reinforcing material such as an inorganic fiber or an organic fiber, a carbon material, a carbide, a nitride, or a metal oxide may be used, as long as the deodorizing effect of the present invention is not reduced. And other additives such as a coloring agent and a coagulant.

The method for producing the photocatalyst material of the present invention includes:
Normally, titanium oxide and an oxidation accelerator may be appropriately added to and mixed with an inorganic curable composition such as synthetic calcium silicate, hydraulic cement, gypsum, etc. in the presence of water, and molded, and if necessary, heated during molding. Alternatively, drying or steam curing may be performed after molding.

For example, when synthetic calcium silicate is used, a predetermined amount of titanium oxide and an oxidation accelerator are mixed with an aqueous slurry of synthetic calcium silicate, and a known molding method such as a press molding method, an extrusion molding method, or a mold molding method is used. And then dried. In this case, the titanium oxide and the oxidation accelerator may be added in advance during the synthesis of calcium silicate.

The shape of the above-mentioned material is not particularly limited and may be appropriately determined according to the use. For example, the material may be formed into a rod shape, a plate shape or the like, or may be formed into a granular shape by granulation.
Moreover, it is also possible to make it into a paper or sheet shape by papermaking, or to make a laminate of these.

The surface protective layer can be formed by applying a sol such as the above-mentioned SiO ₂ or a liquid fluororesin or silicone resin to the surface. The thickness of the surface protective layer is not particularly limited as long as it is within a range where the action of the photocatalyst can substantially function, but is usually about 10 to 100 μm.

In the case of producing the material of the present invention having a surface layer portion of an inorganic cured product, a mixture (dispersion, solution, powder, etc.) of titanium oxide and an oxidation accelerator is applied to the surface of the inorganic cured product or the formed product before curing. It can also be manufactured by applying and spraying, or separately preparing a raw sheet containing the above mixture, laminating this on the surface of the formed body before curing, and pressing by pressure molding or the like.

For example, in the case of manufacturing a molded plate using synthetic calcium silicate hydrate as a base material by a papermaking method, a green sheet serving as a surface layer portion is formed on a green sheet which is formed by laminating a plurality of green sheets. A predetermined amount of the above mixture may be added in advance from the slurry stage, and then the green sheet may be laminated on the green compact and pressed.

In particular, if the above mixture is applied or sprayed on the surface of a normal formed body and then pressed, titanium oxide and most of the oxidation accelerator can be relatively easily embedded in the surface layer of the formed body. Dropping and peeling can be avoided. When water-soluble salts are used as the oxidation promoter, these are used as an aqueous solution, and if these are applied to the surface of the molded body, the oxidation promoter is supported in the inorganic cured body surface layer without pressing. It is possible. When hydraulic cement is used, it can be manufactured by applying a cement mortar obtained by mixing the above mixture with hydraulic cement or the like on the concrete surface.

[0035]

When a malodorous substance comes into contact with the photocatalyst material of the present invention under light irradiation, the action of titanium oxide and an oxidation promoter causes
The malodorous substance is oxidized and decomposed, resulting in deodorization.
This effect lasts for a long time and does not degrade over time.

[0036]

According to the photocatalyst material of the present invention, part or all of the titanium oxide and the oxidation promoter are present in the surface layer of the inorganic cured product, so that the deterioration with time of the catalytic action is suppressed or prevented. As a result, an excellent deodorizing effect can be exhibited over a long period of time.

The material of the present invention includes, for example, nitrogen compounds such as ammonia, amines, indole and skatole; sulfur compounds such as hydrogen sulfide, methyl mercaptan, ethyl mercaptan, methyl sulfide, methyl disulfide and dimethyl disulfide;
Deodorization of malodors and unpleasant odors due to aldehydes such as formaldehyde and acetaldehyde, ketones such as acetone, alcohols such as methanol and ethanol, fatty acids such as acetic acid, aromatic compounds such as benzene and styrene, and alkaloids such as nicotine. It is effective for

Further, the material of the present invention exhibits an antibacterial effect simultaneously with the deodorizing effect, and its function is maintained for a long period of time similarly to the deodorizing effect.

As described above, the photocatalyst material of the present invention can exhibit an excellent deodorizing effect and the like while utilizing the properties of the inorganic cured product. For example, when synthetic calcium silicate is used as the inorganic curable composition, it is possible to obtain a building material or the like having these properties and the fire resistance, heat insulation, adsorption, humidity control and the like of the synthetic calcium silicate.

[0040]

EXAMPLES Examples and comparative examples are shown below to clarify the features of the present invention.

Example 1 Photocatalytic materials (samples A to D) were prepared using synthetic calcium silicate hydrate, gypsum and Portland cement as the inorganic curable composition.

[Sample A] Papermaking was carried out using an aqueous slurry of hydrated synthetic calcium silicate obtained by hydrothermally reacting silica and lime with a large amount of water while stirring with a large amount of water. A sheet was prepared. Next, 17 green sheets were laminated to form a laminate.

On the other hand, synthetic calcium silicate hydrate 75.5
8. Parts by weight, fine particle TiO ₂ powder (manufactured by Ishihara Sangyo Co., Ltd.)
A raw sheet having a mixing ratio of 1 part by weight and 15.4 parts by weight of AgNO ₃ powder (special grade reagent, manufactured by Kanto Chemical Co., Ltd.) was prepared in the same manner as the above-mentioned sheet, and this was stacked on the above-mentioned laminate, and added. It was pressed and dried to obtain a molded body having a density of 0.5 g / cm ³ and a thickness of 12 mm.

[Sample B] As a raw sheet to be stacked on the laminate, 62.5 parts by weight of synthetic calcium silicate hydrate, 7.5 parts by weight of fine TiO ₂ powder (manufactured by Ishihara Sangyo Co., Ltd.) and Fe ₂ ( SO ₄ ) ₃ powder (Kanto Chemical Co., Ltd.)
Except that a raw sheet having a mixing ratio of 30 parts by weight was used, and the density was 0.5 g / cm ³ ,
A molded body having a thickness of 12 mm was produced.

[Sample C] The same fine particles Ti as described above were added to 22.2 parts by weight of Portland cement (manufactured by Ube Industries, Ltd.).
A slurry obtained by adding 22.2 parts by weight of O ₂ powder, 55.6 parts by weight of AgNO ₃ powder and an appropriate amount of water was poured into a mold, and then cured to obtain a plate-like material.

[Sample D] Gaseous hemihydrate gypsum (Reagent 1st grade, manufactured by Kanto Chemical Co., Ltd.) was added to 22.2 parts by weight of fine particles of TiO as described above.
A slurry obtained by adding 22.2 parts by weight of ₂ powder, 55.6 parts by weight of AgNO ₃ powder and an appropriate amount of water was poured into a mold, and then cured to obtain a plate-like material.

The obtained samples A to D were processed so that the surfaces containing titanium oxide and the oxidation accelerator (AgNO ₃ , Fe ₂ (SO ₄ ) ₃ ) each had a size of 25 cm ² , This was dried at 105 ° C. Thereafter, the product was taken out of the dryer, and after 5 minutes, placed in a glass closed container having a capacity of 1.6 liters, and about 150 ppm of ethyl mercaptan was injected in a state where light was blocked. After allowing to stand for about 1 hour while measuring the ethyl mercaptan concentration every predetermined time, 4W
Was turned on at a distance of 2 cm from the container, and the ethyl mercaptan concentration was measured.

The decomposition rate constant of ethyl mercaptan (deodorization due to decomposition) was corrected by correcting the deodorizing effect due to adsorption obtained in a state where light was blocked, from the slope obtained from the graph of the relationship between the irradiation time of ultraviolet light and the natural logarithm of the concentration. Effect).

Comparative Example 1 In sample A of Example 1 described above, the blending ratio of the raw sheet to be superimposed on the laminate was changed to that of synthetic calcium silicate hydrate 89.
A density of 0.5 was obtained in the same manner as in the preparation of Sample A, except that 3 parts by weight and 10.7 parts by weight of the TiO ₂ fine powder of Example 2 were used.
A molded product having a g / cm ³ and a thickness of 12 mm was obtained. The decomposition rate constant of ethyl mercaptan was examined for this molded article in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 In the sample A of Example 1 described above, the TiO ₂ fine powder 0.1
g in ethanol was placed on a glass plate at 25 cm ²
Applied. Using this sample, the decomposition rate constant of ethyl mercaptan was examined in the same manner as in Example 1. Table 1 shows the results.

[0051]

[Table 1]

From the results shown in Table 1, the photocatalyst material of the present invention was
It can be seen that an excellent deodorizing effect can be maintained. In addition, the sample of Example 1 was left to stand, and the deodorizing effect (decomposition rate constant) was examined again. The same effect was maintained.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01J 27/18 B01J 27/232 M 27/232 27/25 M 27/25 31/04 M 31/04 33/00 G 33 / 00 B01D 53/36 H (72) Inventor Toshikatsu Takano Gifu Prefecture, Motosu-gun Hozumi-cho Oda Noda Nitta character Kitanonuma 4064-1 Central Research Institute of Nippon Insulation Co., Ltd. (56) References JP-A-7-462 ( JP, A) JP-A-6-327965 (JP, A) JP-A-6-278241 (JP, A) JP-A-57-144403 (JP, A) JP-A-4-334552 (JP, A) Hei 8-164334 (JP, A) JP 4-17098 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B01J 21/00-38/00 A61L 9/01 B01D 53 / 86

Claims (8)

(57) [Claims] 1. A part or all of at least one kind of an oxidation accelerator comprising a hydroxide, a halide and a salt of a titanium oxide and a transition metal, a noble metal and a rare earth element is present in a surface layer portion of an inorganic cured product. A photocatalyst material, characterized in that: 2. The photocatalytic material according to claim 1, wherein a surface protective layer is further formed on the surface of the material. 3. The photocatalyst material according to claim 1, wherein the material forming the surface protective layer contains an inorganic oxide. 4. An inorganic oxide comprising SiO ₂ , Al ₂ O ₃ , Sb ₂
O ₃ , ZrO ₂ , TiO ₂ , SnO ₂ , Fe ₂ O ₃ , Ce
O _2, WO ₃ and photocatalytic material according to claim 3 wherein at least one of MoO _3. 5. The photocatalyst material according to claim 1, wherein the material forming the surface protective layer contains at least one of a fluorine resin and a silicone resin. 6. The method according to claim 1, wherein the oxidation promoter is Ni, Cr, Fe, Zn,
Ti, Mn, Co, Mo, V, Sr, W, Pd, Au,
Ag, Pt, La, Ce, Pr, Nd, Dy, Ho, E
The photocatalyst material according to claim 1, which is at least one of hydroxides, halides and salts of r and Lu. 7. The inorganic hardened product obtained from an inorganic hardenable composition containing at least one of cement, synthetic calcium silicate, synthetic magnesium silicate and magnesium carbonate as a main component. 2. The photocatalyst material according to 1. 8. After spraying at least one of an oxidation accelerator comprising titanium oxide and a transition metal, a hydroxide of a noble metal and a rare earth element, a halide and a salt on the surface of the formed body before curing of the inorganic cured body, A method for producing a photocatalyst material, wherein the powder is embedded in a surface layer of a formed body by pressing the formed body.