JPH0761876A - Production of inorganic hardened material - Google Patents

Abstract

PURPOSE:To obtain a material having high strength in a size of ordinary building material of general purpose, excellent acid resistance and water resistance, consisting essentially of a water glass-based solid material having excellent acid resistance. CONSTITUTION:Silica-containing inorganic powder comprising 30-50wt.% coarse size particles having 0.1-2mm average particle diameter is blended with one or more of aluminum hydroxide, sodium aluminate, magnesium hydroxide and glass powder and an aqueous solution of a sodium alkali to give a slurry, which is put in a mold, dehydrated, molded and then dried to give a hardened material. The hardened material is further impregnated with an aqueous solution of water glass, dried, impregnated with an aqueous solution of boric acid and dried.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an inorganic cured body, and more particularly to a method for producing an inorganic cured body suitable for a general-purpose building material having high strength, water resistance and acid resistance.

[0002]

2. Description of the Related Art Currently, general-purpose building materials include various concrete secondary products made from cement, gypsum, and lime, gypsum board, lightweight foam concrete and others. These building materials are excellent in that they can be supplied in large quantities and at low cost, but they have poor acid resistance, and the bending strength cannot exceed 100 kg / cm ² unless a reinforcing material such as fiber is used. is there. In particular, recently, there is an increasing demand for general-purpose building materials having acid resistance due to environmental changes such as acid rain.

As a solidifying material excellent in acid resistance, various studies have been made on a material obtained by drying, dehydrating and solidifying a slurry of water glass solution and water glass powder. However, since the dried and solidified product of water glass has no water resistance, various methods have been proposed to improve it.

For example, Japanese Patent Application Laid-Open No. 61-66771 discloses a technique in which aluminum hydroxide is added to water glass and silica to obtain an adhesive which is cured at room temperature and has water resistance. No. 204679, a kaolin group hydrous aluminum silicate material was added to water glass to give 150
A technique for a water-resistant adhesive that heats and solidifies at ~ 500 ° C is disclosed in JP-A-49-87929, in which boric acid, metal oxide or hydroxide is added to water glass powder, and calcium carbonate or the like is mixed as a filler. After making it into a paste form, this is 2
A technique of heating at 00 ° C. and solidifying to obtain a water-resistant coating agent or adhesive is disclosed.

Further, JP-A-52-42045 discloses that water glass, boric acid, oxides, hydroxides and carbonates of metals having a valence of 3 or more and, if necessary, oxides of divalent metals. ,
Use a combination of hydroxide and carbonate to make a paste.
It has been reported that a heat-resistant foam excellent in water resistance is obtained by heating and foaming at 00 to 900 ° C.

[0006] These techniques show aluminum hydroxide, aluminum-containing substances, boron compounds, etc. as additives for the water-glass dried and solidified product to exhibit water resistance, but the water-glass mixture is dehydrated and dried. Nothing has been reported to solve the problem of foaming in forming a cured body.

That is, when a slurry or paste of water glass is dehydrated and dried to obtain a hardened body having a predetermined thickness, the water glass causes foaming due to the diffusion of water in the process, and the bending strength is increased. An excellent cured product cannot be obtained, and no prior art that solves this problem has been known yet. Therefore, a technique for producing a cured product having high water resistance and bending strength by using water glass having excellent acid resistance has not yet been established.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to obtain a material having high strength, acid resistance, and water resistance in a size of an ordinary general-purpose building material, mainly for a solidified product of water glass having excellent acid resistance. It is something to try.

[0009]

According to the present invention, a siliceous inorganic powder containing 20 to 97% by weight of coarse particles having an average particle diameter of 0.1 to 2 mm is added to aluminum hydroxide, sodium aluminate, and hydroxide. At least one of magnesium and glass powder and an aqueous sodium alkali solution are added and kneaded to form a slurry, which is placed in a mold, dehydrated and molded, and then dried to obtain a hardened body. Aluminum impregnated and dried, and then impregnated with an aqueous boric acid solution and dried (claim 1). At least one of sodium, magnesium hydroxide, and glass powder is added to 0.
7. The method for producing an inorganic cured body according to claim 1, wherein 7% by weight or more is added. Hereinafter, these inventions will be further described.

The main raw material of the inorganic cured product of the present invention is one or more of an inorganic powder containing siliceous material, aluminum hydroxide, sodium aluminate, magnesium hydroxide and glass powder. A sodium-alkali aqueous solution is added to this to make a slurry.

The silica-containing inorganic powder used here is, for example, a mixture of sand for cement mortar and silica powder in a weight ratio of 1: 1 to 1: 2.
When a silica-containing inorganic powder is added to a water glass aqueous solution which is a sodium alkali aqueous solution to form a slurry, which is poured into a mold to be pressurized and dehydrated to obtain a cured product,
It is extremely important to control the surface hardening of the cured product and the evaporation of water in the cured product. It is also important to pay attention to the reactivity between the water glass aqueous solution and the siliceous fine powder.

That is, it is necessary to control the curing of the surface of the cured product so that the moisture inside the cured product is sufficiently evaporated. This is because if the surface is cured while the moisture remains inside the cured body, the moisture will evaporate due to the heating during drying, causing delamination and the like inside the cured body.

Therefore, the silica-containing inorganic powder as the raw material of the present invention contains coarse particles having an average particle diameter of 0.1 to 2 mm in an amount of 20 to 20 mm.
When the molded body is dehydrated and dried to form a cured body containing 97% by weight, moisture is efficiently diffused from the coarse grain gaps of the cured body, which causes the cured body to foam and expand during curing. The purpose is to avoid the possibility of delamination.

In addition, as an inorganic powder containing silica,
For example, if a large amount of fine powder of 50 μm or less is used, the water glass powder mixed with this becomes an alkaline sodium aqueous solution to dissolve the siliceous powder, and a high molar ratio (SiO 2
₍₂ / Na ₂ O molar ratio) It becomes a water glass composition and is rapidly cured, which causes peeling of the surface layer of the molded body, delamination of the molded body, and explosion. From this point of view, it is necessary that the siliceous inorganic powder used in the present invention contains coarse particles in the above range.

The silica-containing inorganic powder used in the present invention is not limited to the above-mentioned sand for cement mortar and silica powder mixed in a weight ratio of 1: 1 to 1: 2, and instead of silica powder. In addition to fly ash, EP ash which is an incineration ash of municipal waste, and bug ash, shirasu as a low-grade mineral resource can be used. Even in this case, it is necessary to include coarse particles within the above range, and it is not preferable that these fly ash and the like contain organic substances and clay substances.

A sodium alkali aqueous solution is added to the above raw materials and mixed to form a slurry. The slurry concentration should be such that the raw material can be poured into the mold, and if possible, it is better to use less water. As the sodium alkali aqueous solution, a caustic soda aqueous solution can be used in addition to water glass.

When water glass powder is used, the raw material slurry
It is necessary to add a small amount of caustic soda to the water glass in order to prevent the water glass from being eluted when the water glass is poured into the mold and dehydrated and cured.

A caustic soda is added in place of water glass to prepare a kneaded slurry, which is poured into a mold, dehydrated and cured to obtain a good cured product. In this case, water glass is used. As in the case of using it, there is little risk of expansion, delamination, etc. during curing of the molded body, and therefore it is not necessary to set the above-mentioned limitation on the particle size of the silica-containing inorganic powder, but some coarse particles It is necessary to be included. When using caustic soda, if the concentration of caustic soda solution is 1% or less, the drying and curing are not sufficient, and 15%.
Even if it exceeds, the strength of the cured product will not be further improved. Considering economical efficiency and safety of handling of the molded body, the concentration of the caustic soda solution is preferably in the range of 3 to 10%.

An inorganic powder containing silica is added to an aqueous solution of sodium and alkali to form a slurry, which is poured into a mold and dehydrated and molded, so that the cured product has no water resistance. Therefore, in the present invention, one or more of aluminum hydroxide, sodium aluminate, magnesium hydroxide and glass powder are added to the inorganic powder containing silica. The blending ratio of these additives varies depending on the blending ratio of the fine silica powder in the inorganic powder, the type of the additive, etc., but is 0.7 parts by weight or more, preferably 100 parts by weight or more, with respect to 100 parts by weight of the silica-containing inorganic powder. Is added in the range of 2 parts by weight or more. By using these, the water resistance and water resistance of the cured product obtained by molding the slurry can be remarkably improved.

For example, a mixture of sand and silica powder in a ratio of 1: 1 is mixed with aluminum hydroxide (first-grade reagent) of 1.
3 wt% was added, and this was added to a caustic soda aqueous solution having a concentration of 10% and kneaded to form a slurry, which was then poured into a mold and pressurized at about 10 kg / cm ² and dehydrated to obtain a cured product, 200
It was dried at a temperature of ° C. This was kept in boiling water at 98 ° C for 1 week, but no shape change due to elution was observed (hereinafter referred to as "water resistance").

The cured product was added to boiling water of industrial No. 3 water glass aqueous solution (ratio of undiluted solution: water of 1: 1) to 30.
No change in shape was observed even after immersion for a minute (water resistant glass). Experiments were conducted using sodium aluminate, magnesium hydroxide and glass powder in place of aluminum hydroxide, and it was confirmed that the water resistance and water glass resistance were almost the same.

If the amount of one or more of aluminum hydroxide, sodium aluminate, magnesium hydroxide and glass powder used here deviates from the above lower limits, the water resistance and alkali resistance will decrease, but the upper limits are particularly limited. There is no.

To mold a cured product from this slurry,
The slurry is poured into a mold for dehydration, which can be performed by pressure dehydration, reduced pressure dehydration, or any other known method. After that, it is demolded and dried. Drying is performed at 120 to 350 ° C.
As a result, a water-resistant and water-resistant glass cured product can be obtained.

Next, this molded body is impregnated with water glass. By impregnating this molded body with water glass, the strength of the molded body can be greatly improved. The water glass used here is preferably industrial No. 1, No. 2, No. 3 water glass diluted 1: 1. If the concentration of the aqueous solution of water glass is high, the strength of the cured product cannot be expected to be improved even if the temperature of the impregnating solution is raised to perform the impregnation treatment, and even if the concentration of the water glass is low, sufficient strength cannot be expected. The temperature of the impregnating liquid is preferably in the range of 95 to 100 ° C. Incidentally, in order to dry the cured product after demolding, if the high-temperature cured product just taken out from the dryer is immediately added to the water glass solution, it is possible to expect almost the same impregnation effect as in the case of adding it to the heated water glass solution. I confirmed the result of the experiment.

When the temperature of the water glass impregnating liquid is low, the impregnation treatment time must be significantly lengthened, which is not preferable in terms of productivity. After impregnating the water glass solution with the cured product, it is taken out and dried at 120 to 350 ° C. to obtain a water glass-containing cured product. By such a treatment, the strength can be improved to 2 to 5 times the bending strength of the cured product before impregnation with water glass.

The cured product obtained by the above water glass impregnation treatment is not sufficient in terms of water resistance because water glass adheres to the surface. Therefore, in the present invention, the cured product is impregnated with warm water of a boric acid-impregnated aqueous solution. The boric acid solution used here is preferably a supersaturated solution. Treatment liquid temperature is 70-9
The temperature is preferably 8 ° C., and the treatment time depends on the shape of the cured product such as the plate thickness, and the treatment is performed until boric acid is sufficiently impregnated into the cured product. After impregnating with a boric acid aqueous solution, this is thoroughly dried at 120 to 350 ° C. to obtain a product. The treatment with boric acid is preferably performed at a temperature as high as possible for a short time. For a normal cured product, about 30 minutes is a standard.

A cured product is obtained by the impregnation treatment with this aqueous solution of boric acid, and the strength and water resistance of the cured product can be greatly improved. In addition to boric acid, boron oxide (B
It is also possible to use a solution of ₂ O ₃ ). The present invention will be further described below with reference to examples of the present invention.

[0028]

【Example】

(Examples 1 and 2) As the silica-containing inorganic powder, Toyoura standard sand for cement mortar and Yamagata silica stone No. 8 (silica fine powder) were used in the ratios shown in Table 1. Concentrate this 10%
The mixture shown in Table 1 was prepared by using an aqueous solution of caustic soda and sodium aluminate (reagent). This was stirred and mixed with a mortar mixer for 3 minutes to form a fluid slurry.
This slurry is poured into a mold of size 25 × 25 × 3 (cm), pulp paper is laid on the top and bottom as filter paper, and 10 kg /
It was pressurized, dewatered and molded at cm ² . This is demolded, size 2
It was placed on a stainless steel mesh plate having a size of 5 × 25 (cm) and a thickness of 1.5 mm and dried for 60 minutes by a drier kept at 250 ° C. Then, the molded body was taken out from the dryer and cooled. This cured product substantially maintained the dimensions of the slurry molded product, and did not cause explosion or delamination during drying.

Next, the dried and cured product was immersed in an industrial water glass No. 1 and an aqueous solution diluted with water at a ratio of 1: 1 for 10 minutes for impregnation, and then the surface of the cured product was washed with water and dried at 250 ° C. And dried for 30 minutes. Subsequently, this was impregnated with a boric acid aqueous solution having a concentration of 20% and a temperature of 95 ° C. for 30 minutes, and then 2
The final cured product was obtained by drying for 30 minutes with a dryer maintained at 50 ° C. (Examples 3 to 4) As main materials, Toyoura standard sand for cement mortar and Yamagata silica stone No. 8 (silica fine powder) were used in the ratios shown in Table 1. Also, as a sodium-alkaline aqueous solution,
Commercially available industrial No. 3 water glass powder was used, and caustic soda was used as shown in Table 1. Others were the same as in Examples 1-2. The caustic soda aqueous solution was used in order to prevent the elution of the water glass powder during the slurry kneading. (Example 5) As an aqueous solution of sodium alkali, caustic solution
And aluminum hydroxide (first-grade reagent) as an additive Table 1
In the same manner as in Example 1 except that the amount of water was slightly increased and the amount of water was increased, a cured product was obtained. (Example 6) Example 5 except that boric acid was used in the amounts shown in Table 1.
Same as. It was investigated whether or not the bending strength was affected by using boric acid as an additive. (Example 7) Glass powder was used as an additive in an amount shown in Table 1,
Same as Example 1 except that the amount of water was slightly increased. (Example 8) In the same manner as in Example 7, aluminum hydroxide was used in place of soda aluminate, and the amount of water was slightly increased. (Example 9) In the same manner as in Example 8, a cured product was obtained without using aluminum hydroxide. (Examples 10 to 12) As a siliceous fine powder, Example 10 was used.
Fly ash, Example 11 bug ash, Example 1
In Example 2, EP ash was used, aluminum hydroxide was used in place of soda aluminate as an additive, and the amount of water was slightly changed to obtain a cured product in Example 1. (Examples 13 to 17) As shown in Table 1, standard sand, fine silica powder, water glass, caustic soda, soda aluminate, boric acid, slaked lime, and water were used as raw materials. Molded in the same manner as 1 to obtain a cured product.

In these treatments, the dimensional change of the cured product was hardly observed in the water glass impregnation treatment and the boric acid impregnation treatment, and cracks and other defects were not observed at all. Specimen for testing is a hardened body and a diamond cutter with a size of 1.5 cm x
A piece cut into a size of 1.5 cm × 1.2 cm was used, and the water resistance test was carried out in a water bath heated at 98 ° C. 1
It was put in for a week and then taken out and used in a wet state. In addition,
The bending strength test is performed on a cured product obtained by molding a slurry (dry cured product), a cured product subjected to water glass impregnation treatment (water glass impregnated cured product), and a cured product subjected to boric acid treatment (boric acid treated cured product). went. The results are shown in Tables 1 and 2.

[0031]

[Table 1]

[0032]

[Table 2]

The cured product of Example 1 finally had a bending strength of 1
The water resistance is 17 kg / mm ² and the water resistance is 50.0 kg / mm ² . Further, it is recognized that when the ratio of the fine silica powder is increased as in Example 2, both the bending strength and the water resistance strength are significantly improved. Although Examples 3 and 4 use water glass powder, it can be seen that also in this case, a cured product having high strength can be obtained with the same tendency.

In Examples 5 and 6, caustic soda was used as the sodium-alkaline aqueous solution, and aluminum hydroxide was used as the additive, but good products were obtained. In Example 6, boric acid was added at the slurry stage, but it can be seen that this does not affect the results.

In Examples 7 to 9, the glass powder was used, and in this case, the result similar to the above was obtained. Examples 10 to 12 use fly ash, bag ash, and EP ash as the silica fine powder. In this case, the strength of the product is slightly lower than that of the above, but it has sufficient strength depending on the use such as interior and partition materials. Examples 13 to 17 all have excellent strength. Example 18 A cured product was obtained in the same manner as in Example 1 except that silica powder was used as the siliceous inorganic powder, magnesium hydroxide was used as the additive, and the amount of water was slightly increased. (Example 19) The same as Example 18 except that fly ash was used as the silica-containing inorganic powder and the amount of water was slightly reduced. (Example 20) In the same manner as in Example 19, glass powder was further added to obtain a cured product. The results of Examples 18 to 20 are shown in Table 3.

[0036]

[Table 3]

As shown in Examples 19 and 20, good products can be obtained by using fly ash in the fine siliceous powder. Although the drying temperature for obtaining the cured product was slightly changed, the strength of the product was almost the same. (Example 21) Shirasu (produced in Kagoshima Prefecture) as a low-grade mineral resource was dried and sieved, and a particle size of 0.5 mm or less was used, and a hardened product was obtained in the same manner as in Example 1 with the raw material composition shown in Table 4. It was (Example 22) A cured product was obtained in the same manner as in Example 21, except that magnesium hydroxide was used as an additive in the same manner as in Example 21. The results of Examples 21 to 22 are shown in Table 4.

[0038]

[Table 4] As shown in this table, good products can be obtained by using Shirasu.

[0039]

EFFECTS OF THE INVENTION According to the present invention, it is possible to produce a large-sized cured body which has not been solved mainly by a water glass type solidified material excellent in acid resistance, and thereby excellent in acid resistance, water resistance and heat resistance. Moreover, high strength materials can be obtained at low cost.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C04B 22:06 Z 22:08) A

Claims (2)

[Claims] 1. Coarse particles having an average particle diameter of 0.1 to 2 mm are 20 to
One or more of aluminum hydroxide, sodium aluminate, magnesium hydroxide and glass powder, and 97% by weight of siliceous inorganic powder are mixed with a sodium-alkaline aqueous solution and kneaded to form a slurry. In water, molded, and then dried to obtain a cured product, which is further impregnated with an aqueous solution of water glass, dried, and then impregnated with an aqueous solution of boric acid and dried to produce an inorganic cured product. Method. 2. 0.7% by weight of one or more of aluminum hydroxide, sodium aluminate, magnesium hydroxide and glass powder based on the silica-containing inorganic powder.
The method for producing an inorganic cured body according to claim 1, wherein the above-mentioned addition is performed.