JPH0781996A - Curable inorganic composition - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a curable inorganic composition which can be suitably used as a raw material for producing an inorganic cured product having excellent nonflammability, strength, durability and appearance with high productivity. [Structure] Fly ash containing 80% by weight or more of powder having a particle size of 10 μm or less, which is fired at 400 to 1000 ° C.,
It consists of an alkali metal hydroxide solution or an alkali metal silicate aqueous solution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic cured material which is useful as an interior / exterior wall of a house or building, a flooring material, a building material such as a roof tile, and has excellent nonflammability, strength and durability and an excellent appearance. The present invention relates to a curable inorganic composition that is preferably used as a raw material for forming a body.

[0002]

2. Description of the Related Art Fly ash discharged from thermal power plants has been attempted to be used as a filler for cement. However, due to the recent strengthening of pollution regulations aimed at preventing the generation of nitrogen and sulfur oxides, the fly ash is fired at a low temperature, so that a considerable amount of unburned carbon remains, which causes the characteristics of the fly ash to deteriorate. It was That is, the fly ash cement using such fly ash has a problem that it cannot be used as it is because the cement is blackened and the strength of the concrete is lowered.

As other methods of utilizing fly ash, some proposals have been made for a curable inorganic composition which is cured by heat in the presence of an alkali. For example,
As described in JP-A-4-59648, ash of a dust collector generated during the production of an alkali metal silicate aqueous solution and metakaolin, corundum or mullite, inorganic solid components such as fly ash, and fillers and organic bentonites. It has been proposed to produce an inorganic hardened material useful for building materials by mixing the admixture described in JP-A-4-6.
As described in Japanese Patent No. 138, it has been proposed that an inorganic hardened body is obtained by mixing fly ash with an alkali metal silicate aqueous solution and heating and hardening.

[0004]

However, when a curable inorganic composition of this kind is cured to form an inorganic cured product, the reaction in the molding process is a dehydration mainly involving fly ash and an aqueous metal silicate solution. Volume contraction occurs due to the condensation reaction. Therefore, the strength of the resulting inorganic cured body is apt to crack, and the strength is low, and even if the crack does not occur, there is residual stress in the inorganic cured body, so that the hot water resistance is low and the durability is poor. There is.

The present invention provides a curable inorganic composition capable of solving the above-mentioned conventional problems and obtaining an inorganic cured product having excellent nonflammability, strength and durability and an excellent appearance. It was made for the purpose.

[0006]

The calcined fly ash used in the present invention is a calcined fly ash containing 80% by weight or more of a powder calcined at 400 to 1000 ° C. and having a particle size of 10 μm or less.

The fly ash is a coal-fired power plant.
Of the coal ash discharged from the boilers of
Made of fine ash that passes JIS A 6201
SiO refers to the chemical composition.₂And Al₂O₃
Containing as a main component, Fe ₂O₃, MgO, CaO, etc.
Mixing of crystalline and amorphous materials containing as an accessory ingredient
It has a wide particle size distribution of several to several hundred μm.
Have a cloth.

In the present invention, it is necessary to use a calcined fly ash containing 80% by weight or more of a powder calcined at 400 to 1000 ° C. and having a particle size of 10 μm or less. If the firing temperature is less than 400 ° C, the unburned carbon in the fly ash cannot be removed, and the resulting inorganic cured product has a black color and has a poor appearance. Conversely, if it exceeds 1000 ° C, Since the crystallization of fly ash progresses and the reactivity with the alkali metal hydroxide solution or the alkali metal silicate aqueous solution decreases, the mechanical strength of the obtained inorganic cured body decreases. In addition, when the fly ash containing 80% by weight or more of the powder having a particle size of 10 μm or less is used, the reactivity with the alkali metal hydroxide solution or the alkali metal silicate aqueous solution decreases, so that the obtained inorganic cured The mechanical strength of the body is reduced.

Further, the chemical composition of the calcined fly ash used in the present invention is 40 to 80% by weight of SiO ₂ ,
Al ₂ O _{3 of} 10 to 40% by weight is preferable.

In the present invention, a method for obtaining a calcined fly ash containing 80% by weight or more of powder having a particle size of 10 μm or less, which is calcined at 400 to 1000 ° C., has a particle size of 1
A method of using fly ash containing 80% by weight or more of powder of 0 μm or less and firing it at 400 to 1000 ° C. is adopted.

As a method for producing fly ash having a particle size of 10 μm or less, for example, wet sedimentation classification, wind classification,
It is possible to use a commonly used classification technique such as separation by specific gravity or a pulverization technique with a fine pulverizer such as a jet pulverizer, a ball medium mill, or a roll rolling type pulverizer.

Further, there is provided an internal partial classification type crushing classification system in which a dry type crusher utilizing wind power, a sieve, power, etc. is provided in the crusher, or a closed circuit crushing type crushing classification system in which the above crusher and classifier are continuous. It is effective because the use improves the efficiency of the pulverization process. Above all, a pulverizing / classifying system in which a jet pulverizer and a wind pulverizer are combined is preferable in terms of treatment efficiency and treatment amount.

In the present invention, as the alkali metal hydroxide aqueous solution, one represented by the general formula MOH (M represents Li, K, Na or a mixture thereof) can be used, and the concentration thereof is 1% or more. It is preferably present, and more preferably in the range of 10 to 50%.

In the present invention, the aqueous alkali metal silicate solution has a general formula M ₂ O.nSiO ₂ (M is Li,
K, Na or a mixture thereof and n is 8 or less) can be used. The concentration of the aqueous solution is 1
The range of ˜70% is preferable. When n exceeds 8, the alkali metal silicate aqueous solution is apt to gel and the viscosity rapidly increases, so that it becomes difficult to mix it with the powder.

In the present invention, the amount of the alkali metal hydroxide aqueous solution or the alkali metal silicate aqueous solution added is 10 to 300 with respect to 100 parts by weight of the calcined fly ash.
It is preferably part by weight, more preferably 40 to 250 parts by weight. If the addition amount is less than 10 parts by weight, it will be difficult to knead with the powder, and conversely, if it exceeds 300 parts by weight, the mechanical strength of the obtained inorganic cured product tends to decrease.

In the present invention, an inorganic filler may be added if necessary. Examples of the inorganic filler include silica sand, fly ash, alumina, talc, mica, rock powder, basalt, feldspar, clay, bauxite, fiber materials, various minerals, and the like. These inorganic fillers may be used alone or in combination. The amount of the filler to be added is 10
It is preferably 700 parts by weight or less with respect to 0 parts by weight.
More preferably 0 to 500 parts by weight. If the amount added exceeds 700 parts by weight, the mechanical strength of the resulting inorganic cured product tends to decrease.

In the present invention, a foam such as an organic foam or an inorganic foam may be added if necessary for the purpose of reducing the weight of the material. Examples of the organic foam include granular foam of synthetic resin such as polyvinyl chloride, phenol resin, urea resin, polystyrene, polyurethane and polyethylene.

Examples of the inorganic foam include granular foams such as glass balloons, shirasu balloons, fly ash balloons, silica balloons, perlite, leucite, and granular expanded silica. These foams may be used alone or in combination.

The specific gravity of these foams is preferably 0.01 to 1, and more preferably 0.03 to 0.7. If the specific gravity is less than 0.01, the mechanical strength of the obtained inorganic cured product tends to decrease, and conversely, if it exceeds 1, an effect of reducing the weight of the obtained inorganic cured product is obtained. Tend not to.

The amount of these foams added is preferably 10 to 100 parts by weight, more preferably 30 to 80 parts by weight, based on 100 parts by weight of fired fly ash. Addition amount is 1
If the amount is less than 0 parts by weight, the effect of reducing the weight of the obtained inorganic cured product cannot be obtained, and conversely, if it exceeds 100 parts by weight, the mechanical strength of the obtained inorganic cured product tends to decrease.

Examples of the foaming agent include Mg, Ca, C
r, Mn, Fe, Co, Ni, Cu, Zn, Al, G
Examples include metal powders such as a, Sn, Si, and ferrosilicon, and peroxides such as hydrogen peroxide, sodium peroxide, potassium peroxide, and sodium perborate. Of these, Al metal powder and hydrogen peroxide are preferably used because of their cost, safety, availability, and ease of mixing.

As the foaming agent made of metal powder, those having an average particle size of 1 to 200 μm are preferably used. If the average particle size is less than 1 μm, the dispersibility in the curable inorganic composition decreases, the reactivity becomes high, and foaming becomes too fast. Conversely, if it exceeds 200 μm, the reactivity tends to decrease.

The amount of the foaming agent made of metal powder added is preferably 5 parts by weight or less with respect to 100 parts by weight of calcined fly ash. If the addition amount is more than 5 parts by weight, the foaming gas becomes excessive and the bubbles tend to be broken.

As the foaming agent composed of a peroxide, one having an aqueous solution concentration of 0.1 to 35% is preferably used. When the concentration of the aqueous solution is less than 0.1%, the viscosity is lowered and the foaming is not stable. On the other hand, when it is more than 35%, the foaming tends to be too fast and stable foaming tends to be impossible.
The addition amount of the foaming agent made of peroxide is preferably 4 parts by weight or less with respect to 100 parts by weight of calcined fly ash. If the addition amount is more than 4 parts by weight, the foaming gas becomes excessive and the bubbles tend to be broken.

The foaming aid is added to stabilize foaming. For example, silica gel, zeolite, activated carbon, porous powder such as alumina gel, metal stearate, metal salt such as palmitate, and the like. Is mentioned. The addition amount of the foaming aid is preferably 5 parts by weight or less based on 100 parts by weight of the fly ash. If the addition amount is more than 5 parts by weight, there is a tendency that foaming such as foam breaking is adversely affected.

If desired, reinforcing fibers may be added to the present invention. As the reinforcing fiber, any one can be used depending on the performance to be imparted to the obtained inorganic cured body, for example,
Synthetic fibers made of materials such as vinylon, polyamide, polyester, polypropylene, carbon, aramid, acrylic and rayon, glass fibers, inorganic fibers made of materials such as potassium titanate and steel can be used.

The reinforcing fiber preferably has a fiber diameter of 1 to 500 μm and a fiber length of 1 to 15 mm. The thickness of the reinforcing fiber is
If it is too thin, it reaggregates during mixing, fiber balls are likely to be formed by entanglement, and the strength of the obtained inorganic cured product tends not to be improved anymore.If it is too thick or too short, the reinforcing effect such as tensile strength improvement is small. If the length is too long, the dispersibility and orientation of the reinforcing fibers tend to deteriorate.

The amount of reinforcing fibers added is preferably 10 parts by weight or less with respect to 100 parts by weight of calcined fly ash. If the amount added exceeds 10 parts by weight, the dispersibility of the reinforcing fibers tends to decrease.

As a method of molding an inorganic molded article from the curable inorganic composition of the present invention, the curable inorganic composition of the present invention and, if necessary, an inorganic filler, an organic foam or an inorganic foam, foaming The mixture obtained by kneading the agent, the foaming aid and the reinforcing fiber as a raw material can be molded by a conventionally known method such as a casting method, a pressing method or an extrusion molding method. The inorganic molded body may be cured at room temperature, but is preferably cured by heating at a temperature of 50 to 200 ° C.

[0030]

The inorganic composition of the present invention has a temperature of 400 to 1000 ° C.
Since the burned fly ash containing 80% by weight or more of the powder having a particle size of 10 μm or less, which has been burned in Step 1, and an alkali metal hydroxide solution or an alkali metal silicate aqueous solution, unburned carbon is contained in the burned fly ash. It does not remain, the resulting inorganic cured product does not blacken and has an excellent appearance, and the calcined fly ash has a large specific surface area and high reactivity with an alkali metal hydroxide solution or an alkali metal silicate aqueous solution. The time can be shortened, and it has excellent durability such as nonflammability, strength, and hot water resistance.
In addition, it can be suitably used as a raw material for producing an inorganic cured product having an excellent appearance with high productivity.

[0031]

EXAMPLES Example 1 Fly ash (manufactured by KANDENKA CORPORATION, average particle size 20 μm, specific gravity area 1.8 m ² / g, JIS A 6201 phase equivalent product)
Classifier (manufactured by Nisshin Engineering Co., Ltd., trade name "TC-
15 ") was used to prepare fly ash having a particle size of 10 μm or less. Particle size distribution measuring device (laser diffraction type particle size distribution meter, manufactured by Seishin Enterprise Co., Ltd., trade name "PRO-
7000S ") was used to measure the particle size distribution. As a result, all the particle sizes were 10 μm or less.

100% by weight of powder having a particle size of 10 μm or less
The fly ash containing was baked at a temperature of 600 ° C. to obtain a baked fly ash containing 100% by weight of powder having a particle diameter of 10 μm or less. This baked fly ash 1
00 parts by weight, silica sand (Sumitomo Cement Co., Ltd., Blaine value 50
00 cm ² / g), 350 parts by weight, and 130 parts by weight of a 35% aqueous solution of sodium silicate solution containing 1.5 mol of SiO ₂ per 1 mol of Na ₂ O were supplied to an omni mixer and mixed for 5 minutes.

The mixture obtained is sized 150 × 50 m.
m into a mold with a height of 10 mm and 85 in an oven
It was cured at a temperature of ℃ for 0.5 hours, 1 hour and 5 hours, respectively, to obtain an inorganic cured product. The cured state of the inorganic molded body was judged by observing the demolding state.
The results are shown in Table 1. In Table 1, the mark ◯ indicates that the inorganic molded body was cured to such an extent that it could be released from the mold without breaking, and the mark x indicates that it was broken during the mold releasing.

With respect to the inorganic cured product obtained by curing for 5 hours, bending strength, hot water test and color were measured by the following test methods. The results are also shown in Table 1.

Bending Strength The bending strength of the cured inorganic material was measured according to JIS A 1408. Hot water test The cured inorganic material was left in hot water at 98 ° C or higher for 8 hours,
Cracks and cracks were confirmed. Color The color of the inorganic cured product is based on JIS Z 8729,
The L value was measured.

Example 2 Fly ash containing 100% by weight of powder having a particle size of 10 μm or less and adjusted by classification obtained in Example 1, and a particle size of 1
Fly ash containing 90% by weight of powder having a particle size of 10 μm or less, which was obtained by mixing 9% by weight with fly ash having a particle size of more than 0 μm, was baked at a baking temperature of 600 ° C. A fired fly ash containing 90% by weight of the following powder was obtained. An inorganic cured product was obtained in the same manner as in Example 1 except that this baked fly ash was used. In the same manner as in Example 1, the cured state of the inorganic molded body was determined, and the bending strength, hot water test and color of the inorganic cured body were measured. The results are also shown in Table 1.

Example 3 Fly ash containing 100% by weight of powder having a particle size of 10 μm or less, which was adjusted by classification and obtained in Example 1, and a particle size of 1
Fly ash containing 80% by weight of powder having a particle size of 10 μm or less, which was obtained by mixing fly ash having a particle size of more than 0 μm in a weight ratio of 8: 2, was baked at a baking temperature of 600 ° C. A fired fly ash containing 80% by weight of the following powder was obtained. An inorganic cured product was obtained in the same manner as in Example 1 except that this baked fly ash was used. In the same manner as in Example 1, the cured state of the inorganic molded body was determined, and the bending strength, hot water test and color of the inorganic cured body were measured. The results are also shown in Table 1.

Examples 4 and 5 Based on Example 1, firing fly ash containing 100% by weight of a powder having a particle size of 10 μm or less and the same sand as in Example 1 were fired at the firing temperature shown in Table 1. and predetermined amounts shown in Table 1, except that K ₂ O1 moles of an aqueous solution concentration of 45% potassium silicate solution containing SiO ₂ 1.4 moles using each solution amount shown in Table 1, example 1 An inorganic cured product was obtained in the same manner as in. In the same manner as in Example 1, the cured state of the inorganic molded body was determined, and the bending strength, hot water test and color of the inorganic cured body were measured. The results are also shown in Table 1.

Examples 6 and 7 Particle size 10 μm obtained by firing at a temperature of 600 ° C. obtained in Example 1
A calcined fly ash containing 100% by weight of the following powder, silica sand and vinylon fibers (thickness 1.
8 denier, 6 mm in length) and the respective predetermined amounts shown in Table 1,
The respective predetermined amounts shown in Table 1 of the aqueous alkali silicate solution having the molar ratios and the solution concentrations shown in Table 1 were supplied to an omni mixer and mixed for 5 minutes.

The obtained mixture was heated to 110 ° C., a vibration press molding machine having a size of 150 × 150 mm and a height of 10 mm (manufactured by Asahi Engineering Co., Ltd., trade name “SA-5”).
0 "), molding pressure 69 kg / cm ² , frequency 1
Since vibration was not applied at 000 Hz and an amplitude of 10 μm, press molding and simultaneous curing were performed to obtain an inorganic cured body. Example 1
Similarly to the above, the cured state of the inorganic molded body was determined, and the bending strength, hot water test and color of the inorganic cured body were measured. The results are also shown in Table 1.

COMPARATIVE EXAMPLE 1 Fly ash containing 100% by weight of powder having a particle size of 10 μm or less prepared by classification and having a particle size of 1
Fly ash containing 40% by weight of powder of 10 μm or less obtained by mixing with fly ash exceeding 0 μm in a weight ratio of 4: 6 was fired at a firing temperature of 600 ° C. to obtain 10 μm. A fired fly ash containing 40% by weight of the following powder was obtained.

100 parts by weight of the calcined fly ash, 300 parts by weight of the same silica sand as in Example 1, and 150 parts by weight of potassium silicate having an aqueous solution concentration of 45% containing 1.4 mol of SiO ₂ per 1 mol of K ₂ O were used. An attempt was made to mold an inorganic cured body in the same manner as in Example 1 except for the above. However, the curing time of 1 hour did not cure, and the inorganic cured product obtained by curing for 5 hours was also easily cracked. The results are shown in Table 2.

Comparative Example 2 Fly ash containing 100% by weight of powder having a particle size of 10 μm or less, which was adjusted by classification and obtained in Example 1, and a particle size of 1
Fly ash containing 70% by weight of powder having a particle size of 10 μm or less, obtained by mixing with fly ash exceeding 0 μm in a weight ratio of 7: 3, was baked at a baking temperature of 600 ° C. A fired fly ash containing 70% by weight of the following powder was obtained.

100 parts by weight of this calcined fly ash, 350 parts by weight of silica sand similar to that used in Example 1, and 150 parts by weight of sodium silicate having an aqueous solution concentration of 35% containing 1.5 mol of SiO ₂ per 1 mol of Na ₂ O were used. An attempt was made to mold an inorganic cured body in the same manner as in Example 1 except for the above. However, the curing time of 1 hour did not cure, and the inorganic cured product obtained by curing for 5 hours was also easily cracked. The results are shown in Table 2.

Comparative Examples 3 and 4 According to Example 1, calcined fly ash containing 100% by weight of powder having a particle size of 10 μm or less, calcined at the calcining temperature shown in Table 2, was obtained. Example except that 100 parts by weight of this calcined fly ash, 300 parts by weight of silica sand similar to Example 1 and the amount of each solution shown in Table 2 of the potassium silicate aqueous solution having the molar ratio and the aqueous solution concentration shown in Table 2 were used. An attempt was made to mold an inorganic cured product in the same manner as in 1, but it was impossible to mold. The results are shown in Table 2.

Comparative Example 5 100 parts by weight of fly ash of 100% by weight of powder having an unfired particle size of 10 μm or less, 300 parts by weight of silica sand similar to that of Example 1, 1.4 mol of SiO ₂ to 1 mol of K ₂ O. An inorganic cured product was obtained in the same manner as in Example 1 except that 140 parts by weight of an aqueous potassium silicate solution having an aqueous solution concentration of 45% was used. In the same manner as in Example 1, the cured state of the inorganic molded body was determined, and the bending strength, hot water test and color of the inorganic cured body were measured. The results are also shown in Table 2.

[0047]

[Table 1]

[0048]

[Table 2]

As is clear from Tables 1 and 2, in all of Examples 1 to 7 of the present invention, the curing time was 0.
The inorganic cured product that has been cured for 5 hours or more has good demolding properties, is completely cured, has high bending strength, has no abnormalities in the results of the hot water test, and has excellent durability, and its color. Is L
The value was large (coloring was easy). On the contrary,
In each of Comparative Examples 1 to 4, the curing was poor or the molding was defective, and the inorganic cured body obtained by curing for a long time was also cracked. In the case of Comparative Example 5, , It was possible to obtain only an inorganic cured product having a small L value (difficult to color).

Since the curable inorganic composition of the present invention has the above-mentioned constitution, it is excellent in nonflammability, strength and durability.
In addition, it is possible to obtain an inorganic cured product having an excellent appearance.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area C04B 14:06 Z 16:06) B

Claims (1)

[Claims] 1. A particle size 1 calcined at 400 to 1000 ° C.
A curable inorganic composition comprising a calcined fly ash containing 80% by weight or more of powder of 0 μm or less and an alkali metal hydroxide solution or an alkali metal silicate aqueous solution.