JPH07309617A - Inorganic powder and hardenable inorganic composition - Google Patents

Abstract

PURPOSE:To obtain inorg. metakaolin powder excellent in reactivity with alkali and a hardenable inorg. compsn. excellent in hardening reactivity, having satisfactory moldability and suitable for use as starting material forming an inorg. molded body such as a building material excellent in appearance and strength. CONSTITUTION:Mechanical energy of 0.1-30kw/kg is applied to metakaolin obtd. by dehydrating a kaolin mineral by heating at 500-900 deg.C to obtain the objective inorg. powder and a hardened body excellent in strength and appearance is produced using a hardenable inorg. compsn. contg. 100 pts.wt. of the inorg. powder, 1-300 pts.wt. alkali metallic silicate and 10-1,000 pts.wt. water.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an alkali-reactive inorganic powder and a curable inorganic composition using the inorganic powder.

[0002]

2. Description of the Related Art In Japanese Patent Laid-Open No. 4-59648,
Aqueous alkali metal silicate solution and metakaolin, ash of dust collector generated during the production of corundum or mullite, alkali-reactive inorganic powder such as fly ash, and water, and admixtures such as filler and organic bentonite are mixed if necessary. It has been proposed to produce an inorganic molded body useful for a building material from the curable inorganic composition obtained as described above.

[0003]

However, as a result of examining metakaolin among the alkali-reactive inorganic powders, metakaolin has a poor reactivity with alkali, and thus it is difficult to mix it with an alkali metal silicate aqueous solution. However, there is a problem that the moldability is poor and the strength of the obtained molded product is low.

The present invention solves the above-mentioned problems of the prior art, is a metakaolin-based alkali-reactive inorganic powder having excellent reactivity with alkali, and has excellent curing reactivity, good moldability, appearance and strength. It is an object of the present invention to provide a curable inorganic composition that can be suitably used as a raw material for forming an inorganic molded article such as an excellent building material.

[0005]

In order to achieve such an object, the inorganic powder according to the present invention is metakaolin obtained by heating and dehydrating kaolin mineral at 500 to 900 ° C. for 0.1 to 30 kw. It was obtained by applying mechanical energy of / kg. In the above configuration,
Kaolin mineral is a 1: 1 layered silicate, Al ₂ SiO ₅
It is represented by the chemical formula of (OH) ₄ , and specific examples thereof include kaolinite, dickanite, nacrite and halloysite.

Metakaolin contains 50 of the above kaolin minerals.
It is necessary to perform heat treatment within a temperature range of 0 to 900 ° C. This is because when the heat treatment temperature is less than 500 ° C, hydroxyl groups of kaolin minerals are not eliminated and metakaolin is not transformed, and conversely 900 This is because if the temperature exceeds ℃, crystallization will occur and alkali reactivity will be significantly reduced. A more preferable range is 600 to 800 ° C.

When the heat treatment time is short, metakaolin is not converted, and even when it is long, no further effect can be obtained, so that it is preferably 5 minutes to 10 hours. Further, the higher the heat treatment temperature, the shorter the treatment time may be. The particle size of metakaolin is not particularly limited, but an average particle size of 0.1 to 500 μm is preferable from the viewpoint of effective use of mechanical energy.
More preferably, it is 0.1 to 100 μm.

Applying mechanical energy to the above metakaolin means applying compressive force, shearing force, impact force and the like. Specifically, a crusher generally used for crushing, for example, a ball medium mill (ball mill, vibration mill, planetary mill, etc.) that combines impact, friction, compression, shear, etc. in the crushing mechanism, medium stirring type It is possible to use a mill, a roller mill, a mortar or the like, or a jet crusher whose mainstream is impact and grinding.

The mechanical energy may be added by a dry method or a wet method. In addition, liquid systems centered on alcohols such as methyl alcohol or ethanol / amines such as triethanolamine used for crushing cement clinker, silica sand, limestone, etc., solid systems such as sodium / calcium stearate, and acetone vapor. You may use gas-type grinding aids, such as.

The mechanical energy applied to the powder is
It is limited to 0.1 kwh / kg or more and 30 kwh / kg or less. If it is less than 0.1 kwh / kg, the activity of metakaolin does not increase and the reactivity with alkali is low. On the other hand, 3
When it is more than 0 kwh / kg, the load on the crushing device is large, and the balls as the medium and the container are greatly worn. In addition, problems arise in terms of productivity such as contamination (contamination) in the treated clay and cost. The mechanical energy shown above is the electric power supplied to the pulverizing device when the inorganic powder is put into operation and expressed per unit weight of the treated powder.

The mechanical energy applied to the powder per unit time needs to be in the range of 0.01 to 40 kw / kgh. If it is less than 0.01 kw / kgh, the activity of metakaolin does not increase, and if it exceeds 40 kw / kgh, the load on the crushing device is large, and the balls and the container as the medium are severely worn. Also, contamination of treated clay,
Problems arise in terms of productivity such as cost.

The curable inorganic composition according to the present invention comprises 100 parts by weight of the inorganic powder of the present invention, 1 to 300 parts by weight of an alkali metal silicate, and 10 to 100 parts by weight of water. In the above structure, the alkali metal silicate is represented by M ₂ O · nSiO ₂ (M = Li, K, Na or a mixture thereof), preferably n = 0.05 to 8, and n = 0. 1-3 are more preferable, and 0.5-
2.5 is particularly preferred.

That is, when n exceeds 8, the aqueous solution of the alkali metal silicate is apt to gel, and the viscosity rapidly increases, which may make it difficult to mix with the powder.
The alkali metal silicate is preferably added in an aqueous solution, and the concentration of the aqueous solution is not particularly limited, but if the concentration is too low, the reactivity with the inorganic powder decreases, and conversely, if the concentration is too high, fixed components occur. Since it becomes easy, it is necessary to be 1% or more, preferably 1 to 70%.

Although the alkali silicate aqueous solution may be prepared by dissolving the alkali metal silicate in water as it is, the SiO ₂ component such as silica sand and silica stone powder is added to the alkali metal hydroxide aqueous solution.
May be dissolved in a predetermined amount. The amount of the alkali metal silicate added should be 1 to 300 parts by weight with respect to 100 parts by weight of the inorganic powder.
The amount is preferably set to 10 parts by weight, more preferably 10 to 150 parts by weight.

That is, when the amount of the alkali metal silicate added is less than 1 part by weight, the reactivity with the inorganic powder is low, and conversely, when it exceeds 300 parts by weight, the mechanical strength of the obtained inorganic compact is low. descend. The amount of water added is 10
It is necessary to be 10 to 1000 parts by weight, preferably 10 to 750 parts by weight, based on 0 parts by weight.
It is more preferable that the amount is 400 parts by weight. That is,
When the amount of water added is less than 10 parts by weight, it becomes impossible to mix with the inorganic powder, and conversely, when it exceeds 1000 parts by weight, the mechanical strength of the obtained inorganic molded body decreases.

In the inorganic composition according to the present invention, an inorganic filler may be added if necessary. Examples of the inorganic filler include silica sand, silica stone powder, crystalline alumina,
Fly ash, alumina, talc, mica, diatomaceous earth,
Mica, rock powder (shirasu, firestone, etc.), basalt, feldspar,
Various minerals such as wollastonite, clay, bauxite, sepiolite and fiber materials can be used. These fillers are
The inorganic molded body is appropriately selected according to the intended use and is used alone or in a mixture.

The amount of the inorganic filler added is the amount of the inorganic powder 10
When the amount exceeds 700 parts by weight with respect to 0 parts by weight, the mechanical strength decreases, so the amount is preferably 700 parts by weight or less, and more preferably 50 to 500 parts by weight. In the inorganic composition according to the present invention, if necessary, an organic or inorganic foam may be used for the purpose of reducing the weight of the material.

Examples of the organic foam include granular foams of synthetic resins such as vinyl chloride, phenol, urea, styrene, urethane and ethylene, and examples of the inorganic foam include glass balloons, shirasu balloons and fly ash balloons. , Silica balloons, perlite, hirucite, granular expanded silica and the like. These organic and inorganic foams may be used alone or in combination.

If the specific gravity of the above-mentioned foam is less than 0.01, the mechanical strength of the molded product may be deteriorated, and
If it exceeds 1, the effect of weight reduction cannot be obtained, so 0.01-
1 is preferable, and 0.03 to 0.7 is more preferable. If the addition amount of the foam is less than 10 parts by weight with respect to 100 parts by weight of the inorganic powder, the effect of weight reduction cannot be obtained. On the other hand, if it exceeds 100 parts by weight, the mechanical strength may decrease. The amount is preferably 100 parts by weight, more preferably 30 to 80 parts by weight.

In the inorganic composition according to the present invention, reinforcing fibers may be further added, if necessary. As the reinforcing fiber, any one can be used according to the performance desired to be imparted to the molded product, and examples thereof include synthetic fibers such as vinylon, polyamide, polyester, polypropylene, aramid, acrylic, rayon, carbon, glass fiber, potassium titanate, steel and the like. Inorganic fibers can be used.

If the thickness of the above-mentioned reinforcing fiber is too small, it will be re-aggregated during mixing and fiber balls will be easily formed by entanglement, and the strength of the obtained molded article will not be improved any more, and it will be too thick or short. If it is too long, the reinforcing effect such as improvement in tensile strength is small, and if it is too long, the dispersibility and orientation of the fiber may be deteriorated.
00 μm and a fiber length of 1 to 15 mm are preferable.

Since the dispersibility of the fibers decreases as the amount of the reinforcing fibers added increases, it is preferably 10 parts by weight or less relative to 100 parts by weight of the inorganic powder. As a method for obtaining a molded article from the inorganic composition according to the present invention, the inorganic powder of the present invention, an alkali metal hydroxide aqueous solution or an alkali metal silicate aqueous solution, and if necessary, an inorganic filler, an organic material Conventionally known methods such as casting, pressing and extrusion of a mixture obtained by kneading a foam or an inorganic foam and a reinforcing fiber can be used. The obtained molded product may be cured at room temperature, but it is preferably cured by heating at a temperature of 40 to 200 ° C.

[0023]

According to the above inorganic powder according to the present invention, first, kaolin mineral is heated and dehydrated at 500 to 900 ° C. to obtain metakaolin. When mechanical energy of 0.1 to 30 kwh / kg is applied to the obtained metakaolin, metakaolin is crushed and the specific surface area is increased, so that the reactivity with alkali is improved.

Further, according to the constitution of the curable inorganic composition of the present invention, the inorganic powder of the present invention having improved alkali reactivity, the alkali metal silicate and water are blended. By molding and curing the product, it is possible to obtain a cured product with good moldability, excellent appearance, and strength.

[0025]

EXAMPLES The present invention will be described in detail below with reference to its examples. First, metakaolin (SATINONE SP 33 manufactured by Engelhard Co., average particle size 3.
Using 3 micron and a specific surface area of 13.9 m ² / g), alkali-reactive inorganic powders according to the present invention (hereinafter, referred to as “inorganic powder”) to were obtained by the following method. The mechanical energy applied, the mechanical energy per unit time, and the specific surface area of the obtained inorganic powders are as shown in Table 1. Also, the mechanical energy is
The electric power supplied to the crushing device when operating with the metakaolin was expressed per unit weight of the treated powder. Furthermore, the powder physical property evaluation was performed using the following apparatus.・ Fineness distribution Laser diffraction type particle size distribution analyzer (manufactured by Seishin Enterprise Co., Ltd .: PRO-7000S) ・ Specific surface area automatic specific surface area / pore distribution measurement device (manufactured by Shimadzu Corporation: ASAP2000) (inorganic powder, ) The above metakaolin (average particle size 3.
3 micron) made by Mitsubishi Heavy Industries, Ltd. Ultra Fine Mill AT-20 (using zirconia balls 10 mmφ, ball filling rate 85%, metakaolin mixed amount 1.7 kg, triethanolamine 25% ethanol 75% as grinding aid)
The mixture was added with 10 g of the mixture) and the predetermined mechanical energy shown in Table 1 was applied to obtain an inorganic powder.

(Inorganic powder) The above metakaolin (average particle size: 3.3 microns) was used as a product of Kurimoto Iron Works Co., Ltd. Heidi Mill BX254 (using zirconia balls 10 mmφ,
Table 1 with a ball filling rate of 60% and a metakaolin content of 40 g)
The inorganic powder was obtained by applying the predetermined mechanical energy shown in.

(Inorganic powder) The above-mentioned metakaolin (average particle size: 3.3 microns) is shown in Table 1 by Makino Co., Ltd. ball mill BM150 (using alumina balls 10 mmφ, ball filling rate 60%, metakaolin content 30 kg). A predetermined mechanical energy was applied to obtain an inorganic powder.

[0028]

[Table 1]

As shown in Table 1, each of the inorganic powders according to the present invention has a larger specific surface area than metakaolin as the raw material powder. (Examples 1 to 7 and Comparative Examples 1 to 3) Obtained inorganic powders ~, and inorganic powder selected from the group consisting of the above-mentioned metakaolin as raw material powder and Sumitomo Cement as a filler, Brane Value 5000 cm ² / g), vinylon fiber (Kuraray Co., Ltd., RM182, length 6 mm, diameter 1)
4 μm), K ₂ O: SiO ₂ was supplied to an omnimixer at a ratio shown in Table 2 as an alkaline solution having a molar ratio of 1: 1.4 and a concentration of 45%, and mixed for 5 minutes. The mixture obtained by mixing was poured into a mold of 150 × 50 × 10 mm and cured by curing in an oven at 85 ° C. for 10 hours to obtain a mold-shaped cured body.

The cured product thus obtained was dried at 50 ° C. for 5 hours, and then the flexural strength and gloss of the test piece which had been left in the air-dried state for 24 hours were examined, and the result was used as an index of moldability. It is shown in Table 2 together with the viscosity of the mixture (paste). In addition, in Table 2, the inorganic powder represents metakaolin as a raw material powder. Also, the viscosity of the mixture,
The bending strength and glossiness were examined by the following methods. Viscosity of Mixture The viscosity of the paste obtained by mixing with the above formulation was measured with a B-type viscometer. Bending Strength The bending strength of the obtained test piece was measured according to the method of JIS A 1408. Glossiness The glossiness of the surface of the obtained test piece was measured according to JIS Z 874.
It measured according to the method of 1.

[0031]

[Table 2]

From Table 2, it can be seen that the cured products obtained in Examples 1 to 7 are superior in bending strength and gloss to the cured products obtained in Comparative Examples 1 to 3. Further, it can be seen that the viscosity of the mixture used is low and the moldability is excellent.

[0033]

Since the inorganic powder according to the present invention is constituted as described above, it has a large specific surface area and excellent reactivity with an alkaline liquid. And, the curable inorganic composition according to the present invention, as the alkali-reactive inorganic powder, since the inorganic powder according to the present invention excellent in reactivity to an alkaline liquid is used, excellent moldability, and dense. It is possible to obtain a cured product having excellent appearance and strength.

Claims (2)

[Claims] 1. Metakaolin obtained by heating and dehydrating a kaolin mineral at 500 to 900 ° C. is 0.1 to 3 parts.
An inorganic powder obtained by applying mechanical energy of 0 kwh / kg. 2. 100 parts by weight of the inorganic powder according to claim 1, 1 to 300 parts by weight of an alkali metal silicate, and 10 parts of water.
~ 1000 parts by weight of a curable inorganic composition.