JPH08243402A - Photocatalst material and its manufacture - Google Patents

Abstract

PURPOSE: To cause a deodorizing material to demonstracte its deodorizing effect for a long time by providing a part or the whole of titanium oxide and an oxidization accelerator on the surface layer of an inorganic cured body. CONSTITUTION: An inorganic cured body is composed of an inorganic curing composition composed of at least one kind of cement, Synthetic calcium silicate, synthetic magnesium silicate and magnesium carbonate. A part or the whole of titanium oxide and an oxidiation accelerator is provided on the surface layer of the inorganic cured body. The kind of titanium oxide is not restricted, and titanium oxide for decomposing a malodorous substance as a catalyst in the existence of light can be used, and anatase type TiO2 fine powder is applicable. As for the oxidization accelerator, a substance to accelerate the catalyst action of titanium oxide can be used, and for example, transition metal, precious metal or the like can be used. Also a surface protection layer can be formed on the surface of the photocatalyst material.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Various odorous substances that cause bad odors, unpleasant odors, etc. are present in living spaces of houses, offices, factories and the like. Therefore, various fragrances,
Although deodorization and deodorization are carried out with activated carbon or the like, it is necessary to frequently replace the fragrance with a new one because a chemical solution needs to be replenished and the activated carbon has a relatively short life and is difficult to regenerate.

As a method of 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 photocatalytic reaction is utilized to decompose the malodorous substances. The method using an inorganic cured body as
It doesn't exist yet. Therefore, the present inventor has attempted to develop a photocatalyst material in which a photocatalyst substance is supported on an inorganic cured body.
However, when a photocatalyst material is produced by incorporating titanium oxide, which is a typical substance as a photocatalyst, into an inorganic hardened material, it has been found that the deodorizing effect thereof deteriorates over time.

[0004]

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

[0005]

Means for Solving the Problems As a result of intensive studies in view of the above-mentioned problems of the prior art, the present inventor has found that in the case where titanium oxide and a specific oxidation promoter coexist in an inorganic cured product,
Unexpectedly, they have found that a material exhibiting a decomposing action of a malodorous substance over a long period of time can be obtained, and completed the present invention.

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

The present invention will be described in detail below.

The inorganic cured product used in the photocatalyst material of the present invention means an inorganic curable composition having a property of being hardened by hydration bond, precipitation of crystals or carbonation after kneading with water, by heating at the time of wet molding. It means a cured product obtained from an inorganic curable composition having a property of curing, or an inorganic curable composition having a property of curing by drying or steam curing after wet molding.

Specifically, it is obtained from an inorganic curable composition containing cement, synthetic calcium silicate, synthetic magnesium silicate, and magnesium carbonate as a main component, such as a pneumatic cement, a hydraulic cement or Examples thereof include an inorganic hardened body which is hardened by hydration bond, crystal precipitation or carbonation after kneading a special cement with water, an inorganic hardened body obtained from magnesium carbonate, synthetic calcium silicate or synthetic magnesium silicate.

As the air-hardening cement, for example, gypsum,
Examples include magnesia cement and lime. The lime includes quick lime, slaked lime, lime plaster, lime mortar, dolomite plaster and the like, and the gypsum includes hemihydrate gypsum, gypsum plaster and the like. The air-hardening cement can be used as a hardened product obtained by, for example, kneading it with water or the like and then drying it to cure it by hydration bonding, precipitation of crystals or carbonation. When using a cured product of gypsum, after kneading hemihydrate gypsum with water, etc., a cured product of dihydrate gypsum obtained by drying, or hemihydrate gypsum or anhydrous gypsum obtained by further heating this cured product A cured product can also be used.

Examples of hydraulic cements include Portland cement, alumina cement, and mixed cement. Hydraulic cement is, for example, a hardened product obtained by kneading this with water and solidifying it by hydration bonding, or concrete products such as concrete, slate, and mortar obtained by kneading hydraulic cement with water, sand, etc. Included in the hardened body of hydraulic cement.

As a special cement, one of refractory cement
Examples include seeds such as hydraulic refractory mortar.

It is particularly preferable to use basic magnesium carbonate as the magnesium carbonate. The hardened body containing basic magnesium carbonate as a main component is obtained by adding water to basic magnesium carbonate powder, and further adding and mixing auxiliary raw materials such as fibrous substances, if necessary, after dehydration molding and drying. The molded product obtained in this way, or the basic magnesium carbonate molded product obtained by subjecting the raw material slurry containing normal magnesium carbonate to heat treatment during dehydration molding can be used as the inorganic cured product. In addition, basic magnesium carbonate, normal magnesium carbonate, etc. may be mixed in these molded articles.

The synthetic calcium silicate is obtained by a hydrothermal reaction from a lime raw material and a silicic acid raw material, for example, zonotolite, tobermorite, fosjagit, gyrolite, α-dicalcium silicate, tricalcium silicate, hirebrandite. , Rosenhanite, Truscotite, Lrierite, Calcio chondrodite, Kircoinite, Affilite, Synthetic calcium silicate hydrate (CSHn), etc.,
Examples thereof include synthetic calcium silicates such as wollastonite obtained by heating synthetic calcium silicate hydrates such as xonotlite and tobermorite.

The inorganic hardened material containing calcium silicate as a main component may be prepared by any known method. For example, by synthesizing an aqueous slurry containing the above calcium silicate and dehydrating and drying it, or by adding a fibrous auxiliary material to a raw material slurry consisting of a lime raw material and a silicic acid raw material, steam-curing it after papermaking A molded product obtained by the above can be used.

As the inorganic hardened body containing synthetic magnesium silicate as a main component, known ones can be used. For example, JP-A-58-9812 and JP-B-61-489.
Examples include molded bodies disclosed in Japanese Patent Publication No. 76, etc.

Of the above-mentioned inorganic curable compositions, those which are hardened by dry molding, such as powders of synthetic calcium silicate, basic magnesium carbonate, etc., can be used as the above-mentioned inorganic hardened bodies. it can.

Among these inorganic hardened materials, those obtained from an inorganic hardened composition containing at least one of synthetic calcium silicate, hydraulic cement, gypsum and basic magnesium carbonate as a main component are preferable. Further, among these inorganic hardened materials, if one having a property of itself adsorbing a malodorous substance such as synthetic calcium silicate is used, the malodorous substance can be effectively decomposed and removed, which is particularly excellent. A deodorizing effect and the like can be obtained.

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

The type of the oxidation accelerator is not particularly limited as long as it has a function of promoting the catalytic action of titanium oxide, but transition metals, noble metals and rare earth elements, oxides, hydroxides and halogens are included. It is preferable to use at least one of a compound and a salt. As salts,
Inorganic acid salts such as sulfates, nitrates, phosphates and carbonates, and organic acid salts such as acetates can be used. Among these oxidation promoters, Ni, Cr, Fe, Zn, Ti, Mn, Co,
Mo, V, Sr, W, Pd, Au, Ag, Pt, La,
Ce, Pr, Nd, Dy, Ho, Er and Lu simple substance,
It is more preferable to use at least one of oxides, hydroxides, halides and salts. More specific examples include iron sulfate Fe ₂ (SO ₄ ) ₃ and silver nitrate AgNO ₃ .

Part or all of the titanium oxide and the oxidation accelerator are present in the surface layer of the inorganic cured product. This includes not only the case where the titanium oxide and the oxidation accelerator are present inside the surface of the cured product, but also the case where they are present on the surface of the cured product. However, if titanium oxide and an oxidation promoter are present on the surface of the cured product, a large amount of titanium oxide and the oxidation promoter will cause them to fall off and peel off easily. It is better to be doing.

Here, the surface layer of the cured product means a range in which titanium oxide and an oxidation accelerator capable of exerting a deodorizing effect 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 the inside of about m.

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

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

As described above, in the present invention, as long as a predetermined amount of titanium oxide and an oxidation accelerator are contained in the surface layer of the cured body, it may be contained in the cured body or may not be contained at all. But 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 existing in the vicinity of the surface from falling off or peeling 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 due to titanium oxide and the oxidation promoter, but among them, inorganic oxides, resins and the like are preferable, and particularly inorganic oxides are used. SiO ₂ , Al ₂ O ₃ , Sb ₂ O ₃ , ZrO ₂ ,
It is desirable to use a resin containing 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 fluororesin 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 may contain calcium carbonate or 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 added as needed within the range where the deodorizing effect of the present invention is not reduced. It is also possible to add an infrared shielding material such as, or the like, or to add aluminum hydroxide, clays, or the like for the purpose of improving heat resistance, or to add various additives such as a coloring agent and a coagulant.

The method for producing the photocatalytic material of the present invention includes:
Generally, synthetic calcium silicate, hydraulic cement, gypsum, and other inorganic curable compositions may be appropriately added and mixed with titanium oxide and an oxidation accelerator 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 known molding method such as a press molding method, an extrusion molding method, or a mold molding method is used in which a predetermined amount of titanium oxide and an oxidation accelerator are mixed in an aqueous slurry of the synthetic calcium silicate. It is obtained by drying after forming into a desired shape with. 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 application, and it may be formed into a rod shape, a plate shape or the like, or may be granulated by granulation.
Further, it is also possible to make paper or sheet by paper making, or to make a laminate of these.

The surface protective layer can be formed by coating the surface of the sol such as SiO ₂ or the liquid fluororesin or silicone resin. The thickness of the surface protective layer is not particularly limited as long as 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 body, a mixture (dispersion, solution, powder, etc.) of titanium oxide and an oxidation accelerator is applied to the surface of the inorganic cured body or the green body before curing. It is also possible to manufacture by applying or spraying, or separately preparing a raw sheet containing the above mixture, laminating it on the surface of the green body before curing, and then pressing it by pressure molding or the like.

For example, in the case where a molded plate having a synthetic calcium silicate hydrate as a base material is manufactured by a paper-making method, a green sheet which is a surface layer portion of a green body formed by laminating a plurality of green sheets is used for paper-making. A predetermined amount of the 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 mixture is applied or sprinkled on the surface of a normal molded body and then pressed, most of titanium oxide and most of the oxidation promoter can be embedded in the surface layer of the molded body. It is possible to avoid falling and peeling. When a water-soluble salt is used as the oxidation accelerator, these are used as an aqueous solution and applied to the surface of the molded body, so that the oxidation accelerator is supported in the surface layer of the inorganic cured body without pressing. It is possible. When hydraulic cement is used, it can be produced by coating the concrete surface with cement mortar in which the above mixture is mixed with hydraulic cement or the like.

[0035]

When a malodorous substance comes into contact with the photocatalyst material of the present invention under the irradiation of light, the action of titanium oxide and the oxidation promoter causes
As a result of the malodorous substance being oxidized and decomposed, it is deodorized.
This effect is long-lasting and does not deteriorate over time.

[0036]

EFFECTS OF THE INVENTION According to the photocatalyst material of the present invention, titanium oxide and the oxidation accelerator are partially or wholly present in the surface layer portion of the inorganic cured body, so that the deterioration of the catalytic action with time is suppressed or prevented. As a result, an excellent deodorizing effect can be exhibited over a long period of time.

The materials of the present invention include, for example, nitrogen compounds such as ammonia, amines, indole and skatole, hydrogen sulfide, sulfur compounds such as methyl mercaptan, ethyl mercaptan, methyl sulfide, methyl disulfide and dimethyl disulfide,
Deodorization of odors and unpleasant odors caused by 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. Is effective for.

Further, the material of the present invention exerts an antibacterial action at the same time as the deodorizing action, and its function is maintained for a long period of time like the deodorizing action.

As described above, the photocatalyst material of the present invention can exhibit an excellent deodorizing effect and the like while making the best use of the characteristics of the inorganic cured body. For example, when synthetic calcium silicate is used as the inorganic curable composition, it is possible to obtain a building material having these characteristics and the fire resistance, heat insulating property, adsorptive property, and humidity control property of the synthetic calcium silicate.

[0040]

EXAMPLES Hereinafter, examples and comparative examples will be shown to clarify the features of the present invention.

Example 1 Photocatalyst materials (Samples A to D) were prepared by using synthetic calcium silicate hydrate, gypsum and Portland cement, respectively, as an inorganic curable composition.

[Sample A] Papermaking was carried out using an aqueous slurry of a synthetic calcium silicate hydrate obtained by hydrothermally reacting silica stone and lime with stirring in a large amount of water, and a raw material having a thickness of about 1.2 mm was prepared. A sheet was prepared. Then, 17 of these green sheets were laminated to form a laminate.

On the other hand, synthetic calcium silicate hydrate 75.5
Parts by weight, fine particle TiO ₂ powder (manufactured by Ishihara Sangyo Co., Ltd.) 9.
A raw sheet having a mixing ratio of 1 part by weight and 15.4 parts by weight of AgNO ₃ powder (special reagent grade manufactured by Kanto Kagaku Co., Ltd.) was prepared in the same manner as the above-mentioned sheet, and this was laminated on the above-mentioned laminate and added. It was pressed and dried to obtain a molded product having a density of 0.5 g / cm ³ and a thickness of 12 mm.

[Sample B] As a green sheet to be laminated on the laminate, 62.5 parts by weight of synthetic calcium silicate hydrate, 7.5 parts by weight of fine particle TiO ₂ powder (manufactured by Ishihara Sangyo Co., Ltd.) and Fe ₂ ( SO ₄ ) ₃ powder (special grade Kanto Chemical Co., Ltd.)
(Manufactured) except that a green sheet having a mixing ratio of 30 parts by weight was used, and the density was 0.5 g / cm ³ , in the same manner as in the case of the sample A.
A molded body having a thickness of 12 mm was produced.

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

[Sample D] 22.2 parts by weight of hemihydrate gypsum (first-grade reagent, manufactured by Kanto Chemical Co., Inc.) was added to the same fine particle TiO as described above.
₂ powder 22.2 parts by weight, AgNO ₃ powder 55.6 parts by weight and an appropriate amount of water were added and mixed the slurry poured into a mold frame, to obtain a plate-like material and thereafter curing.

The obtained samples A to D were processed so that the surface containing titanium oxide and the oxidation promoters (AgNO ₃ , Fe ₂ (SO ₄ ) ₃ ) each had a size of 25 cm ² . It was dried at 105 ° C. After that, it was taken out from the dryer, and after 5 minutes, it was placed in a glass closed container having a capacity of 1.6 liters, and about 150 ppm of ethyl mercaptan was injected while the light was blocked. After standing for about 1 hour while measuring the concentration of ethyl mercaptan for each predetermined time, 4W
The UV lamp of No. 2 was turned on at a distance of 2 cm from the container, and then the concentration of ethyl mercaptan 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 rays and the natural logarithm of the concentration. Effect).

Comparative Example 1 In the sample A of Example 1 above, the blending ratio of the green sheet to be overlaid on the laminate was the 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 body having a g / cm ³ and a thickness of 12 mm was obtained. The decomposition rate constant of ethyl mercaptan of this molded product was examined in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 In the sample A of the above Example 1, 0.1% of TiO ₂ fine powder was used.
25 cm ^{2 of} g dispersed in ethanol on a glass plate
Applied. Using this sample, the decomposition rate constant for 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 is
It can be seen that the excellent deodorizing effect can be sustained. Further, the sample of Example 1 was allowed to stand still and the deodorizing effect (decomposition rate constant) was examined again, but the same effect was maintained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshikatsu Takano 4064-1, Kitanuma, Noda Nitta, Hozumi-cho, Motosu-gun, Gifu Japan Insulation Co., Ltd.

Claims (9)

[Claims] 1. A photocatalyst material, characterized in that titanium oxide and a part or all of an oxidation promoter are present in the surface layer portion of an inorganic cured body. 2. The photocatalytic material according to claim 1, further comprising a surface protective layer 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. The inorganic oxide is SiO ₂ , Al ₂ O ₃ or S.
b ₂ O ₃ , ZrO ₂ , TiO ₂ , SnO ₂ , Fe
_At least 1 of ₂ O ₃ , CeO ₂ , WO ₃ and MoO ₃
The photocatalytic material according to claim 3, which contains a seed. 5. The photocatalyst material according to claim 1, wherein the material forming the surface protective layer contains at least one of a fluororesin and a silicone resin. 6. The photocatalyst material according to claim 1, wherein the oxidation accelerator is at least one selected from the group consisting of transition metals, noble metals and rare earth elements, oxides, hydroxides, halides and salts. . 7. 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 6, which is at least one of simple substance of r and Lu, oxide, hydroxide, halide and salt. 8. The inorganic curable body is obtained from an inorganic curable composition containing as a main component at least one of cement, synthetic calcium silicate, synthetic magnesium silicate and magnesium carbonate. The photocatalytic material described in 1. 9. A method for spraying titanium oxide and an oxidation promoter onto the surface of a green molded body before curing of an inorganic cured body, and then pressing the green molded body to embed the powder in a surface layer of the green molded body. A method for producing a photocatalytic material.