JPH08196902A - Inorganic cured material for air purification - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an inorganic cured body for air purification that can adsorb and decompose low-concentration NOx at low cost and can be used even in places where nonflammability is required. [Constitution] 8 fly ash powders with a particle size of 10 μm or less
Powder containing 0% by weight or more, powder containing 80% or more of fired fly ash powder having a particle size of 10 μm or less, powder obtained by melting fly ash and spraying it into gas, and melting clay into gas Powder obtained by spraying the powder, powder obtained by applying mechanical energy to clay, and metakaolin 0.1 to 3
100 parts by weight of at least one kind of reactive inorganic powder selected from the group consisting of powder obtained by applying mechanical energy of 0 kwh / kg, and titanium dioxide 5 to 50
A mixture containing 0 parts by weight, an alkali metal silicate, and water as a mixture was cured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cured inorganic material for air purification.

[0002]

2. Description of the Related Art Conventionally, zeolite supporting platinum, palladium, rhodium, vanadium, etc. has been used as a decomposition catalyst for nitrogen oxides, so-called NOx, contained in exhaust gas. Its purpose is to reduce the concentration of NOx, and it can exhibit its performance only at relatively high temperatures. Therefore, there is a problem that energy is required for heating and the use cost is high, and further, low concentration NOx is released into the atmosphere without being decomposed.

Therefore, titanium dioxide (TiO ₂ ) or a mixture of titanium dioxide and activated carbon (hereinafter referred to as “photocatalyst”) that exhibits catalytic activity by irradiating ultraviolet rays having a wavelength range of 300 to 400 nm is used in this low concentration. It is attracting attention as a new material that adsorbs and decomposes NOx concentration. And
For example, (1) heating and melting the photocatalyst powder together with the glaze on the tile to solidify and fix it to make a deodorant,
(2) It has already been proposed that a photocatalyst powder is mixed with a fluororesin as a binder, and the mixture is rolled into a sheet or panel to be used as an air purification material (see Japanese Patent Laid-Open No. 06-315614). There is.

[0004]

However, when the photocatalyst powder is heated and melted together with the glaze to be solidified and fixed as in the deodorant of the above (1), the photocatalyst powder is sintered in the heating and melting process. Therefore, there is a problem that the specific surface area of the photocatalyst itself is greatly reduced and the ability as a catalyst is reduced.

On the other hand, the air-purifying material (2) formed by mixing with a fluororesin cannot be used in a place where nonflammability is required, and its use is limited. There was a problem. In view of such a situation, the present invention aims to provide an inorganic cured body for air purification that can adsorb and decompose low-concentration NOx at low cost and can be used even in a place where nonflammability is required. I am trying.

[0006]

The cured inorganic substance for air purification according to the present invention has the following objects and advantages.
80% by weight of fly ash powder with a particle size of 10 μm or less
Powder containing the above, powder containing 80% or more of fired fly ash powder having a particle size of 10 μm or less, powder obtained by melting fly ash and spraying it into gas, and melting clay and spraying it into gas 0.1 to 30 kwh to powder obtained by the above, powder obtained by applying mechanical energy to clay, and metakaolin
100 parts by weight of at least one kind of reactive inorganic powder selected from the group consisting of powder obtained by applying mechanical energy of / kg, titanium dioxide 5 to 500 parts by weight, alkali metal silicate, A mixture containing water as a compound was cured.

In the above structure, fly ash is J
Fine ash particles collected by a dust collector from a pulverized coal combustion boiler specified by ISA 6201, containing 45% by weight or more of silica, moisture 1% or less, ignition loss 5% or less, specific gravity 1 It has a specific surface area of 0.95 or more and a specific surface area of 2700 cm ² / g or more and 75% or more passes through a 44 μm standard sieve.

Then, in the reactive inorganic powder, the powder is
It can be obtained by a conventionally known method in which the above fly ash is classified by a sieve, specific gravity, wind force, wet settling or the like, or pulverized by a jet mill, a roll mill, a ball mill or the like. Moreover, these methods may be used in combination. If the amount of fly ash powder having a particle size of 10 μm or less in the powder is less than 80% by weight, the reactivity with the alkali metal silicate is lowered.

The powder of the reactive inorganic powder can be obtained by further firing the above powder. The firing temperature is preferably 400 ° C to 1000 ° C.
That is, if the baking temperature is lower than 400 ° C, the black color of fly ash remains in the obtained powder, which becomes an obstacle when the cured body needs to be colored. If the baking temperature is higher than 1000 ° C, the reaction with the alkali metal silicate occurs. There is a risk that it will become less active.

In the production of the powder and the powder in the reactive inorganic powder, a method of melting the raw material powder such as fly ash or clay and spraying it into the gas is as follows: Melted at 30-8
A spraying method at a speed of 00 m / sec is preferable, and for example, a spraying technique applied to a ceramic coating such as a plasma spraying method, a high energy gas spraying method, an arc spraying method can be applied.

[0011] Powder and powder obtained in this way, the specific surface area thereof is preferably about 0.1 to 100 m ² / g, further preferably about 0.1~60m ² / g. Mechanical energy applied to clay and metakaolin as raw material powders for producing powders and powders in reactive inorganic powders refers to compression force, shearing force, impact force, etc. It may be allowed to act, or two or more kinds may be combined or allowed to act. Also,
The means for applying such mechanical energy is not particularly limited, and examples thereof include ball mill, vibration mill, planetary mill, medium agitation mill, roller mill, mortar, jet pulverizer, and the like.

When the amount of mechanical energy to be applied decreases, the reactivity with the alkali metal silicate decreases, and when it increases, the load on the crushing device and the like increases and the wear of the device increases, resulting in impurities in the inorganic powder. Therefore, the content is limited to 0.1 to 30 kwh / kg, preferably 1.0 to 26 kwh / kg. In addition, a grinding aid may be added, if necessary, when applying mechanical energy. The grinding aid is added in order to prevent the powder from adhering to the inside of the apparatus when it is subjected to mechanical energy, or to prevent remarkable aggregation. For example, alcohols such as methyl alcohol and ethyl alcohol, triethanolamine, etc. Examples thereof include alcohol amines, metal soaps such as sodium stearate and calcium stearate, and acetone vapor. These may be used alone or in combination of two or more.

Further, if the powder is further heated, the reactivity with the alkali metal silicate can be improved and the strength of the cured product can be improved. The method for further heating the powder is not particularly limited, and a conventionally known heating device such as a gear oven or a rotary kiln can be arbitrarily used. The heating temperature is preferably 100 to 750 ° C, and more preferably 200 to 600 ° C, because the effect of increasing the strength of the cured product is poor when the heating temperature is low, and the crystallization of the inorganic powder tends to be promoted when the heating temperature is high. If the heating time is short, the effect of increasing the strength of the cured product is poor, and if the heating time is long, the energy cost tends to increase.
5 hours is preferred.

As the powder and the clay used for producing the powder, SiO _{2 5 to} 85% by weight, Al ₂ O
Those containing ₃ 90-10% by weight as a chemical component. Examples of such clays include kaolin minerals (kaolinite, dickanite, nacrite, halloysite, etc.), mica clay minerals (muscovite, illite, phengite, seacoast, celadonite, paragonite, blancmalite, etc.), smectites (montmorillonite, By date, nontrolite, savonite, sauconite, etc.),
Chlorite, pyrophyllite, talc, vermiculite, wax, and shale shale are used, but not limited to these as long as the composition and particle size are appropriate.

The titanium dioxide used in the present invention is preferably anatase type because of its high activity,
It may be a rutile type or plate titanium stone. When the amount of titanium dioxide is small, the NOx decomposing ability cannot be sufficiently obtained, and when the amount is large, the strength of the obtained inorganic hardened product is lowered. Therefore, 5 to 500 parts by weight relative to 100 parts by weight of the above reactive inorganic powder. Limited to, preferably 10 to 30
The amount is 0 parts by weight, more preferably 25 to 200 parts by weight.

The alkali metal silicate used in the present invention is a salt represented by M ₂ O.nSiO ₂ (one or more kinds of metal selected from M = K, Na and Li), and the value of n. When it is smaller, a dense inorganic cured product cannot be obtained, and when it is larger, the viscosity of the aqueous solution tends to increase and mixing tends to be difficult, so 0.05 to 8 is preferable, and 0.5 is more preferable.
~ 2.5.

The alkali metal silicate is preferably added in the form of an aqueous solution, and the concentration of the aqueous solution is not particularly limited, but when it becomes thin, the reactivity with the above reactive inorganic powder decreases, and when it becomes thick, the solid content becomes large. 10-6 because it tends to occur
0% by weight is preferred. The above-mentioned alkali metal silicate aqueous solution may be prepared by dissolving the alkali metal silicate as it is in water under pressure and heating. However, in the alkali metal hydroxide aqueous solution, SiO ₂ components such as silica sand and silica stone powder are n-doped. May be produced by melting under pressure and heating so that the value becomes a predetermined value.

If the amount of the alkali metal silicate compounded is small, the curing will not be sufficient, and if it is too large, the water resistance of the resulting inorganic cured product will be reduced, so that it is 0 based on 100 parts by weight of the reactive inorganic powder. 2 to 450 parts by weight is preferable, 10 to 350 parts by weight is more preferable, 20 to 25 parts by weight.
0 parts by weight is especially preferred. The water blended in the mixture is
It may be added as an alkali metal silicate aqueous solution,
It may be added independently. If the amount of water added is small, it will not be sufficiently cured, and if it is large, the strength of the resulting inorganic cured product tends to decrease, so 35 to 1500 parts by weight is preferred relative to 100 parts by weight of the reactive inorganic powder, It is more preferably 45 to 1000 parts by weight, and particularly preferably 50 to 500 parts by weight.

In the present invention, when light is not irradiated,
Activated carbon may be added for the purpose of supplementing NOx decomposing ability at the time of outdoor use at night or in cloudy weather. The activated carbon has a large specific surface area because it has a large contact area with the atmosphere, but is not particularly limited. If the amount of activated carbon is small, NOx decomposition cannot be sufficiently compensated, and if the amount is large, the strength of the inorganic hardened product decreases, and incombustibility decreases, so 1 to 250 parts by weight is added to 100 parts by weight of the above reactive inorganic powder. preferable.

In the present invention, if necessary, an inorganic filler, a foaming agent, a foaming aid, a reinforcing fiber, a lightweight aggregate, etc. may be added to the curable inorganic composition. The inorganic filler can suppress shrinkage during curing and drying, but it is particularly preferable that the inorganic filler has low activity with respect to an alkali metal silicate aqueous solution. Examples of such inorganic fillers include silica sand, zircon sand, crystalline alumina, rock powder, volcanic ash (shirasu, anti-firestone, etc.), wollastonite, calcium carbonate, silica stone powder, diatomaceous earth, mica, talc, wax. Examples thereof include rustite and silica fume, but are not limited to these as long as the activity is low with respect to the alkali metal silicate aqueous solution. The reason why the inorganic filler is desired to have low activity with respect to the alkali metal silicate aqueous solution is that if the activity is high, gelation of the alkali aqueous solution and the alkali metal silicate aqueous solution proceeds rapidly, and mixing and molding become difficult. This is because there is a fear.

Further, the inorganic filler has a lower mechanical strength when the compounding amount thereof is increased, and the drying shrinkage is caused when the compounding amount thereof is decreased.
Since the heat shrinkage may not be improved, 20 to 800 parts by weight is preferable, and 30 to 600 parts by weight is more preferable, relative to 100 parts by weight of the reactive inorganic powder. The foaming agent is not particularly limited as long as it can react with the above aqueous solution of alkali metal silicate such as hydrogen peroxide solution or metal powder such as aluminum to generate gas.

The foaming aid is not particularly limited as long as it uniformly causes foaming by the foaming agent, and examples thereof include fatty acid metal salts such as zinc stearate, calcium stearate and zinc palmitate, silica gel, zeolite, activated carbon, alumina powder and the like. And the like. These may be used alone or in combination of two or more.

When the amount of the foaming aid added is increased, the viscosity of the curable inorganic composition increases, a stable foam cannot be obtained, and the foaming tends to occur. It is preferable to add 10 parts by weight or less to 100 parts by weight. The reinforcing fiber can be any one depending on the performance desired to be imparted to the cured body, for example, vinylon fiber, polyamide fiber, polyester fiber, polypropylene fiber, carbon fiber, aramid fiber, glass fiber,
Potassium titanate fiber, steel fiber, etc. can be used.

The fiber diameter and fiber length of the reinforcing fibers are preferably 1 to 500 μm and 1 to 15 mm.
That is, when the fiber diameter becomes too thin, it reaggregates during mixing, fiber balls are easily formed by entanglement, the strength of the finally obtained inorganic cured body is not further improved, and the fiber diameter becomes too thick or If the length is too short, the reinforcing effect such as improvement in tensile strength will be small, and if the fiber length is too long, the dispersibility and orientation of the fibers may be deteriorated.

The amount of the reinforcing fiber added is not particularly limited, but is 10 per 100 parts by weight of the reactive inorganic powder.
It is preferably less than or equal to parts by weight. Light weight aggregates are added for the purpose of reducing the weight of cured products, and include inorganic natural foams such as silica balloons, perlite, fly ash balloons, shirasu balloons, glass balloons, foamed and baked clay, phenolic resins, urethane resins, polyethylene. Examples thereof include synthetic resin foams and vinylidene chloride balloons. These may be added alone or in combination of two or more kinds.

The curable inorganic composition of the present invention is usually prepared by first dissolving the alkali metal silicate in water under pressure and heating to give an aqueous solution of alkali metal silicate, and then adding the reactive inorganic powder to the aqueous solution. It can be obtained by mixing the body and, if necessary, water, an inorganic filler, a foaming agent, a foaming aid, a reinforcing fiber, a lightweight aggregate, etc., and forming a paste. And the curable inorganic composition thus obtained is generally cast,
It can be molded into a desired shape and cured by a conventionally known method such as press molding or extrusion molding.

The curing temperature may be room temperature, but it is 50 to 110.
By curing at 30 ° C. for 8 minutes, the curing reaction can be promoted and the mechanical properties can be improved.

[0028]

According to the above structure, titanium dioxide as a photocatalyst can be manufactured without applying heat such as sintering. Further, since it does not contain a combustible component, it does not burn even if heat is applied.

[0029]

EXAMPLES The present invention will be described in detail below with reference to its examples. First, reactive inorganic powders-and reactive inorganic powders were produced as follows. [Reactive inorganic powder,] fly ash (manufactured by KANDENKA CORPORATION, average particle size 20 μm; conforms to JIS A 6201), classifier (manufactured by Nisshin Engineering, model; TC
-15) classify and powder 1 with a particle size of 10 μm or less
Reactive inorganic powder containing 100% by weight and having a particle size of 10
A reactive inorganic powder containing 100% by weight of powder exceeding μm was obtained.

The above particle size was measured by a laser diffraction type distribution meter (manufactured by Seishin Co., Ltd., model: PRO700S). [Reactive inorganic powder]
Powder 100 having a particle size of 10 μm or less, which is fired at a temperature of 0 ° C.
Calcined fly ash containing wt% was obtained as a reactive inorganic powder.

[Reactive Inorganic Powder] Fly ash as a raw material powder (manufactured by KANDENKA CORPORATION, average particle size 20 μm; JI
80 (after conforming to SA6201) at 3000 ° C.
It was sprayed into the atmosphere at a speed of m / s and collected as a reactive inorganic powder. The reactive inorganic powder obtained had an average particle size of 5 μm and a specific surface area of 9.5 m ² / g.

[Reactive Inorganic Powder] Kaolin (composition: SiO ₂ 45.7%, Al ₂ O ₃ 38.
3% average particle size: 8 μm BET specific surface area 5.8 m ² /
g) was melted at 2500 ° C., sprayed in the air at a speed of 50 m / s, and collected as a reactive inorganic powder. The composition of the obtained reactive inorganic powder is SiO ₂ 49.7%,
Al ₂ O ₃ 47.0%, average particle size 14.8 μm, BET
The specific surface area was 1.96 m ² / g.

[Reactive Inorganic Powder] Kaolin (Composition:
SiO ₂ 45.7%, Al ₂ O ₃ 38.3%, average particle size 8 μm, BET specific surface area 5.8 m ² / g) 95 parts by weight and quartz (Sumitomo Cement's trade name: soft silica) 5
To 0.5 parts by weight of a mixed solution of 25 parts by weight of triethanolamine and 75% by weight of ethanol into Ultra Fine Mill AT-20 (manufactured by Mitsubishi Heavy Industries, Ltd., zirconia ball 10 mmφ used, ball filling rate 85% by volume). Supply and apply 25 kwh / Kg of mechanical energy,
A reactive inorganic powder was obtained. The mechanical energy applied was expressed by the electric power supplied to the ball mill per unit weight of the treated powder.

[Reactive Inorganic Powder] Metakaolin (SATINTONE SP 33 manufactured by Engelhard Co.,
Average particle size 3.3 μm Specific surface area 13.9 m ² / g) 10
0 parts by weight and 0.5 parts by weight of a mixed solution of 25% by weight of triethanolamine and 75% by weight of ethanol are supplied to Ultra Fine Mill AT-20 (manufactured by Mitsubishi Heavy Industries, Ltd., zirconia ball 10 mmφ used, ball filling rate 85% by volume). Then, mechanical energy of 10 kwh / Kg was applied to obtain a reactive inorganic powder. The mechanical energy applied was expressed by the electric power supplied to the ball mill per unit weight of the treated powder.

(Examples 1 to 15 and Comparative Examples 1 to 10) Si
Alkali metal silicate having a molar ratio of O ₂ / M ₂ O of 1.8 (molar ratio of Na and K of 1: 1) was added in an autoclave at a predetermined amount at a temperature of 130 ° C. and a pressure of 7 kg / cm ² . To the alkali metal silicate aqueous solution obtained by dissolving in water,
The desired reactive inorganic powder, vinylon fiber (manufactured by Kuraray Co., product number; RM182 × 3), and zinc stearate were added at the mixing ratio shown in Table 1 or Table 2 and mixed by a hand mixer for 3 minutes. . Table 1 shows the resulting mixture.
Alternatively, titanium dioxide (manufactured by Ishihara Sangyo Co., Ltd., product number: C-2) having a mixing ratio shown in Table 2 was added and further mixed for 3 minutes to obtain a curable inorganic composition. The curable inorganic composition thus obtained was cast into a mold and heated together with the mold in an oven at 85 ° C. for 6 hours to obtain an inorganic cured product. The obtained inorganic cured product was demolded and dried at 85 ° C. for 4 hours. Bending strength, NOx decomposition efficiency, NOx decomposition efficiency after water resistance test, and noncombustibility of the inorganic cured products obtained in Examples 1 to 15 and Comparative Examples 1 to 10 were examined, and the results are shown in Table 1 or Table 2. It is also shown.

Comparative Example 11 100 parts by weight of polytetrafluoroethylene resin (fluorine resin) and 50 parts of titanium dioxide were added.
By weight, 20 parts by weight of activated carbon were mixed to form a plate. The bending strength, the NOx decomposition efficiency, the NOx decomposition efficiency after the water resistance test, and the nonflammability of the obtained molded body were examined, and the results are shown in Table 2. Bending strength, NOx decomposition efficiency, water resistance test
The NOx decomposition efficiency and nonflammability were examined as follows.

[Bending Strength] The obtained inorganic cured product was used as an evaluation sample for 20 days. And JISK 6
According to 911, from this evaluation sample, width 50 mm, length 200
mm, 10 mm thick strips were cut out and a 3-point bending test was performed with a span of 170 mm to measure the bending strength.

[NOx Decomposition Efficiency] In order to confirm the NOx decomposition efficiency, a NOx resolution measuring device shown in FIG. 1 was prepared, and the obtained inorganic cured body was cut into tiles of 50 mm × 50 mm × 10 mm to obtain an evaluation sample 7. This evaluation sample 7 was placed in each of two Petri dish reaction vessels 6 one by one. Then, the evaluation sample 7 is irradiated with ultraviolet rays having a wavelength of 365 nm from the fluorescent lamp 8 for photochemistry, and the high-pressure container 1 for pollutants is added to the air sent out from the high-purity high-pressure container 2 at a flow rate of 0.5 l / min. Was mixed in front of the reaction vessel 6 so that the initial concentration was 1.0 ppm, and then the mixture was fed into the reaction vessel 6 to adjust the concentration of nitric oxide in the air discharged from the reaction vessel 6. Chemiluminescence type nitrogen oxide meter 9
The decomposition efficiency was determined by measuring by. In addition, in FIG.
Is a pressure reducing valve, 4 is a precision flow rate controller, 5 is a 4-way switching valve,
Reference numeral 10 is an air pump, and 11 and 12 are exhaust ports.

[NOx Decomposition Efficiency After Water Resistance Test] The obtained inorganic cured product was immersed in water at 90 ° C. for 8 hours, and the NOx decomposition efficiency was measured in the same manner as above. [Non-flammability test] The non-flammability test was based on the Ministry of Construction Notification No. 1828, and the obtained cured product was cut into 40 × 40 × 50 mm and used as an evaluation sample.

The obtained evaluation sample was inserted into a furnace in which the temperature inside the furnace was stable at 750 ° C. for 25 minutes at each reading of the two thermocouples, and was subjected to the above-mentioned nonflammability test. (In the table, pass is indicated by ○, fail is indicated by X.)

[0041]

[Table 1]

[0042]

[Table 2] It can be seen from Tables 1 and 2 that the inorganic cured product according to the present invention can decompose low-concentration NOx by irradiation with ultraviolet rays. Moreover, since it is excellent in strength and has nonflammability, it can be used in a place where nonflammability is required, and it can be seen that it has a wide range of use.

[0043]

EFFECTS OF THE INVENTION Since the air-cured inorganic hardened material according to the present invention is configured as described above, it is possible to decompose low-concentration NOx by the irradiation of ultraviolet rays to purify the atmosphere, and It is also excellent in nonflammability and can be used in panels for building materials that require nonflammability.

That is, it can be used in various places.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a NOx resolution measuring device used for investigating the resolution of NOx.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location B01J 21/16 ZAB A C04B 12/04 14/30 28/24 (72) Inventor Yasuaki Hayamizu Shiga Prefecture 1971 Koshinohara, Yasu-cho, Yasu-gun

Claims (1)

[Claims] 1. A powder containing 80% by weight or more of fly ash powder having a particle size of 10 μm or less, a powder containing 80% or more of calcined fly ash powder having a particle size of 10 μm or less, and a fly ash melted in a gas. 0.1 to 30 kwh / kg of powder obtained by spraying, powder obtained by melting clay and spraying in a gas, powder obtained by applying mechanical energy to clay, and metakaolin 100 parts by weight of at least one kind of reactive inorganic powder selected from the group consisting of powders obtained by applying mechanical energy of, titanium dioxide 5 to 500 parts by weight, alkali metal silicate, and water. An air-purified inorganic cured product obtained by curing a curable inorganic composition containing a.