JPH08268774A - Production of inorganic expanded body - Google Patents

Abstract

PURPOSE: To easily produce an inorg. expanded body almost free from broken foam on the surface and excellent in appearance without reducing productivity or requiring further equipment investment. CONSTITUTION: When a compsn. prepd. by mixing reactive inorg. powder such as fly ash with an alkali metallic silicate, water and a blowing agent made of metal powder or hydrogen peroxide is filled into a molding tool and hardened by heating to produce an inorg. expanded body, the compsn. is filled into the molding tool immediately after preparation and the molding tool is put in a heater previously set at a prescribed hardening temp. before the beginning of expansion or before expansion proceeds.

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 foam used for building materials and the like, which has almost no broken cells on the surface and has an excellent appearance.

[0002]

[Prior art]

(A) Reactive inorganic powder, (B) Alkali metal silicate,
Bubbles are generated on the surface of the inorganic foam obtained by filling a composition obtained by mixing a foaming agent composed of (C) water and (D) metal powder or hydrogen peroxide into a molding die and curing it by heating. However, there are problems such as foam breakage and poor appearance, and difficult painting. As a related technique for improving this, Japanese Patent Laid-Open No. 5-131416 discloses that a slurry is cast in a molding mold coated with a release agent, and then the molded building material is subjected to autoclave curing. In the method for manufacturing an ALC building material, a surface active agent (surfactant) is added to the release agent.
A method of manufacturing building materials has been proposed. However, this method requires a step of applying a release agent into the molding frame, and thus has a problem that the step is complicated and the productivity is reduced.

In Japanese Patent Laid-Open No. 3-219913, a water-permeable sheet is laid on the surface of the molding die and the inner surface of the mold, and a cement powder and water are sprinkled on the sheet to form a high specific gravity slurry layer, which is then lightweight. There has been proposed a method for producing a lightweight cellular concrete plate having a densified smooth surface skin layer, which is characterized by casting an aerated cement slurry and curing it. However, this method reduces the productivity due to the complicated process, and requires an apparatus for forming a high specific gravity slurry layer and an apparatus for forming a lightweight aerated cement slurry layer. There is a problem that equipment such as a mixer and a mixer is required twice as much as usual, resulting in a large capital investment.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems and to reduce the productivity of an inorganic foam which has almost no bubble breakage on the surface and an excellent appearance, and a new facility. The object is to provide a method that can be easily manufactured without requiring investment.

[0005]

Means for Solving the Problems As the reactive inorganic powder (A) used in the present invention, SiO ₂ , Al ₂ O ₃ ,
Metal oxides such as ZnO, MgO, CaO, SrO; Ca
(OH) ₂ , Al (OH) ₃ , Mg (OH) ₂ , Zn
Metal hydroxide such as (OH) ₂ ; Na ₂ SiF ₆ , K ₂ S
SiFs such as iF ₆ ; Al (PO ₃ ) ₃ , AlPO ₄ ,
Al (H ₂ PO ₄ ) ₃ , Mg (H ₂ PO ₄ ) ₂ , ZnO
Metal phosphates such as P ₂ O ₅ ; metal borates such as KBO ₂ and CaB ₄ O ₇ ; metal powders such as Mg and Zn; gypsum; cement; slag and the like can be used alone or in combination of two or more.

As the above reactive inorganic powder (A), S
An iO ₂ —Al ₂ O ₃ based powder is particularly preferable. SiO ₂ −
The composition of the Al ₂ O ₃ based powder is SiO ₂ / Al ₂ O
₃ = 1/9 to 9/1 (weight ratio) is preferable, and when the ratio of the total amount of SiO ₂ and Al ₂ O _{3 to} the entire powder particles becomes small, the amount of the alkali metal silicate (B) becomes The reactivity is low and the water resistance of the inorganic foam may be low, so 50% by weight or more is preferable. Such SiO ₂ —Al ₂ O ₃ -based powder is used, for example, in the production of fly ash; corundum or mullite as described in JP-B-3-9060 and JP-B-4-45471. Electric dust collector ash generated;
Examples include metakaolin; pulverized and calcined bauxite, but not limited to these as long as the composition is appropriate.

The alkali metal silicate (B) used in the present invention acts as a curing agent for the reactive inorganic powder (A), and nSiO ₂ / M ₂ O (M is K, Na
And one or more metals selected from Li). If the value of n is small, a dense foam cannot be obtained, and if it is large, the viscosity of the aqueous solution increases and mixing becomes difficult, so 0.05 to 8 is preferable, and 0.5 to 2.5 is more preferable.

The alkali metal silicate (B) is preferably added in the form of an aqueous solution when the composition is prepared, and the concentration of the aqueous solution is not particularly limited, but if it becomes low, the reaction with the reactive inorganic powder (A) occurs. Since the solidity tends to be generated when the property becomes low and the property becomes high, the content is preferably 10 to 60% by weight.

In the preparation of the above-mentioned alkali metal silicate aqueous solution, the alkali metal silicate (B) may be dissolved in water as it is under pressure and heating, but silica sand, silica stone powder, etc. may be added to the alkali metal hydroxide aqueous solution. The SiO ₂ component may be dissolved under pressure and heating so that n becomes a predetermined amount.

When the amount of the alkali metal silicate (B) is small, the composition is not sufficiently cured, and when the amount is large, the water resistance of the inorganic foam is lowered, so that the reactive inorganic powder (A) 100 is used. 0.2 to 450 parts by weight is preferable, 10 to 350 parts by weight is more preferable, and 2
Particularly preferred is 0 to 250 parts by weight.

The water (C) used in the present invention may be added as the above-mentioned alkali metal silicate aqueous solution or may be added independently. When the amount of water (C) decreases,
The composition does not cure sufficiently, mixing becomes difficult, and the strength of the inorganic foam tends to decrease if the amount increases, so that the content of the reactive inorganic powder (A) is from 35 to 35 parts by weight.
1500 parts by weight is preferable, 45 to 1000 parts by weight is more preferable, and 50 to 500 parts by weight is particularly preferable.

The foaming agent (D) used in the present invention comprises metal powder or hydrogen peroxide. These foaming agents are those in which foaming is not completed immediately after mixing the foaming agents in the preparation of the composition. In the present invention, the composition is filled into the mold immediately after preparation, and before or almost the start of foaming. Before the heating, the foaming is substantially started by putting it in a heating device set to a predetermined curing temperature in advance, and the foaming is gradually performed during the heating and curing, so that it is used in the present invention.

Examples of the above metal powder include Al and M
g, Ca, Cr, Mn, Fe, Co, Ni, Cu, G
Examples thereof include a, Sn, Si, and ferrosilicon, but Al is preferable in consideration of cost, safety, availability, mixing, and the like. Further, as the average particle diameter of the metal powder, when the average particle diameter is small, the dispersibility in the composition is lowered, and the foaming is apt to occur rapidly, and when the average particle diameter is large, the reactivity is apt to be lowered. Is preferred.

When using the above hydrogen peroxide, safety,
Considering stable foaming, it is preferably used as an aqueous solution.

When the amount of the foaming agent (D) added is small, the expansion ratio of the obtained inorganic foam is small, and when it is large, the foaming gas is excessive and the foam is broken, or the strength of the inorganic foam is significantly reduced. The reactive inorganic powder (A) 100 may be used because handling may not be possible.
0.01 to 10 parts by weight is preferable with respect to parts by weight.

If necessary, the composition used in the present invention contains a foaming aid, an inorganic filler, a reinforcing fiber, a lightweight aggregate,
A pigment or the like may be added.

The foaming aid is not particularly limited as long as it uniformly causes foaming, 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 foaming aid increases, the viscosity of the composition increases,
Since foam breakage is likely to occur, it is preferably 10 parts by weight or less with respect to 100 parts by weight of the reactive inorganic powder (A).

The above-mentioned inorganic filler is not particularly limited as long as it does not dissolve in water, does not hinder the curing reaction of the composition, and does not react with the alkali metal silicate (B). Quartz sand; River sand; Zircon sand; Crystalline alumina; Rock powder; Volcanic ash; Silica flour; Silica fume; Silica fume; Bentonite; Blast furnace slag and other mixed cement admixtures; Is mentioned. These may be added alone or in combination of two or more.

When the average particle size of the above-mentioned inorganic filler is small, the viscosity of the composition increases, and a high-magnification foam cannot be obtained. When it becomes large, the foaming becomes unstable.
01 to 1000 μm is preferable. When the amount of the inorganic filler increases, the strength of the obtained inorganic foam decreases, so that the amount is 700 with respect to 100 parts by weight of the reactive inorganic powder (A).
It is preferably less than or equal to parts by weight.

As the reinforcing fiber, any fiber can be used according to the performance desired to be imparted to the obtained inorganic foam, 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.

If the fiber diameter of the above-mentioned reinforcing fiber becomes thin, it will be re-aggregated during mixing and fiber balls will be easily formed by entanglement, and the contribution to the strength improvement of the resulting inorganic foam will be reduced, and if it becomes thick, the tensile strength will be improved. The fiber diameter is preferably from 1 to 500 μm, because the reinforcing effect of is reduced.
When the fiber length of the reinforcing fiber is short, the reinforcing effect such as improvement in tensile strength is small, and when the fiber length is long, the dispersibility and orientation of the fiber are deteriorated. Therefore, the fiber length is preferably 1 to 15 mm. Since the dispersibility of the fibers decreases as the amount of the reinforcing fibers increases, it is preferably 10 parts by weight or less with respect to 100 parts by weight of the reactive inorganic powder (A).

The above-mentioned lightweight aggregate is used for the purpose of reducing the weight of the obtained inorganic foam. For example, silica balloons, perlite, fly ash balloons, shirasu balloons, glass balloons, foamed clay and other inorganic materials are used. Foams; foams of synthetic resins such as phenol resins, urethane resins, polyethylene; polyvinylidene chloride balloons and the like. These may be used alone or in combination of two or more.

The above-mentioned pigment is preferably a pigment composed of a metal oxide. As the amount of the pigment increases, the viscosity of the composition increases, which causes foaming failure and lowers workability. Therefore, 50 parts by weight or less relative to 100 parts by weight of the reactive inorganic powder (A) is used. preferable.

Further, if necessary, for the purpose of preventing the shrinkage of the inorganic foam or increasing the reaction rate of the composition, alumina cement, γ-alumina, sprayed alumina,
You may add an alkali metal aluminate, aluminum hydroxide, etc.

In the method for producing an inorganic foam of the present invention, first, a reactive inorganic powder (A), an alkali metal silicate (B), water (C) and a foaming agent (D) composed of a metal powder or a peroxide. ) Are mixed to prepare a composition. The above-mentioned mixing can be performed by using an ordinary machine for mixing cement mortar or concrete or a high-speed stirring type mixer. The order of mixing varies depending on the combination of substances constituting the composition, but the following method is preferable.
First, the alkali metal silicate (B) and water (C) are mixed, and a foaming aid, an inorganic filler, a reinforcing fiber, a lightweight aggregate, a pigment, etc., which are added as necessary, are mixed therein. Next, after the reactive inorganic powder (A) is added and mixed, the foaming agent (D) is finally added and mixed. When mixing the water (C) with the alkali metal silicate (B), a part of the water used in the final composition is used, and the remaining water is the reactive inorganic powder. When (A) or the foaming agent (D) is mixed, it may be mixed and added thereto.

Next, the slurry-like composition obtained as described above is filled into a molding die immediately after preparation. After filling, the mold may be vibrated for defoaming if necessary. Next, the mold filled with the composition is put in a state in which a rapid evaporation of water is not caused before the foaming is started or before the foaming is almost started, for example, by covering the mold with a lid so that the water is not rapidly evaporated. Put in a heating device set to the curing temperature. The heating device is not particularly limited, for example,
There is an oven. The curing temperature is 50 to 110 ° C.
Is preferred. Next, it is foamed and cured while being placed in the heating device. The curing time is preferably 30 minutes to 8 hours.
After the curing is completed, the obtained inorganic foam is removed from the mold. After demolding, it may be dried at 40 to 80 ° C. for 30 minutes to 5 hours in order to evaporate excess water, if necessary.

[0027]

The composition used in the present invention is a thermosetting material, but the reaction gradually progresses and the viscosity gradually rises even when left at room temperature. In addition, foaming starts 1 to 5 minutes after mixing the foaming agent. It is generally known that uniform bubbles can be obtained within a proper viscosity range at a certain foaming pressure.
Therefore, conventionally, the viscosity of the material is adjusted so that the viscosity is appropriate during foaming. Conventionally, heating is usually started after the end of foaming, at which time the gas inside the bubbles expands due to heating. Further, since the viscosity of the alkali metal silicate aqueous solution has temperature dependence, the viscosity of the material is lowered by heating. Therefore, the pressure rise inside the bubbles due to heating and the decrease in the viscosity of the material itself cause bubble breakage, resulting in a poor appearance of the resulting inorganic foam.

However, in the production method of the present invention, the composition is filled into the mold immediately after preparation, and immediately after that, before the foaming is started or before the foaming is almost started, the heating device is set to the curing temperature in advance. Put in. According to the method of the present invention, since it is put into the heating device substantially before the start of foaming, when the viscosity at the start of heating is low, almost no bubbles are generated or the bubbles are small. It does not break. After that, when the bubbles grow sufficiently, the curing of the material progresses by heating and the viscosity increases, so that the bubbles do not break even when the bubbles expand, so that an inorganic foam having an excellent appearance can be obtained.

[0029]

EXAMPLES The present invention will be described in more detail by way of examples. First, the materials and molds used are as follows.

Material Reactive inorganic powder (A): Fly ash (JIS A
According to 6201, manufactured by KANDENKA CORPORATION, average particle size 20
μm) classifier (manufactured by Nisshin Engineering, model: T
C-15), containing 100% by weight of powder having a particle size of 10 μm or less. Alkali metal silicate (B): nSiO ₂ / M ₂ O (n =
1.8, M is a mixture of Na and K in a molar ratio of 1: 1). Foaming agent (D): Aluminum powder (manufactured by Minarco, trade name: 350F, average particle size 13 μm). Foaming aid: zinc stearate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: SZ-2000). Inorganic filler: Silica powder (Sumitomo Cement Co., Ltd., trade name: Soft Silica) and Wollastonite (Tsuchiya Kaolin Co., Ltd., trade name: Chemolit A-60). Reinforcing fiber: Vinylon fiber (Kuraray, trade name: RM1
82 × 3). Others: Alumina cement (Asahi Glass Co., Ltd., trade name: Asahi Alumina Cement No. 1). This was used to prevent shrinkage of the inorganic foam.

Inner dimension of 300 × 300 m with bottom of mold and openable lid
m, height 75 mm, in iron box-shaped mold, outside dimension 298
× 298 mm, height 10 mm, and the upper surface is decorated with a split stone pattern. A urethane rubber decorative mold is pushed in until it reaches the bottom of the iron mold with the decorative surface facing upward. I made a mold. Therefore, when the mold is filled with the composition, the composition is brought into contact with the decorative surface.

(Example 1) 130 parts by weight of an alkali metal silicate aqueous solution consisting of 63 parts by weight of alkali metal silicate and 67 parts by weight of water, 2.5 parts by weight of zinc stearate, 100 parts by weight of silica stone powder, wollastonite 50 parts by weight and 2.5 parts by weight of vinylon fiber were put into an omni mixer (manufactured by Chiyoda Giken Co., Ltd.) and mixed for 3 minutes. Fly ash 1
00 parts by weight and 25 parts by weight of alumina cement were added and mixed for another 3 minutes. Aluminum powder 0.17
After adding 5 parts by weight and mixing for 30 seconds, the obtained composition was charged into a molding die and then vibrated. The vibration was performed from 1 minute after the start of charging. After covering the mold after vibration,
It was placed in an oven which had been set to a curing temperature of 85 ° C. in advance. After 6 hours, remove the mold from the oven,
Remove the resulting inorganic foam from the mold and remove it at 50 ° C for 2
After drying for an hour, an inorganic foam was obtained.

Example 2 An inorganic foam was obtained in the same manner as in Example 1 except that the amount of aluminum powder used in Example 1 was changed from 0.175 parts by weight to 0.35 parts by weight. It was

Comparative Example 1 A composition was prepared in the same manner as in Example 1. The composition obtained was placed in a mold and then vibrated. The vibration was performed from 1 minute after the start of charging. The vibrating mold was left at room temperature. After 30 minutes of standing at room temperature, foaming was completed. Next, the mold was covered with a lid, and then the mold was placed in an oven whose curing temperature was set to 85 ° C. in advance. After 6 hours, the mold was taken out of the oven, the obtained inorganic foam was removed from the mold, and dried at 50 ° C. for 2 hours to obtain an inorganic foam.

Comparative Example 2 A composition was prepared in the same manner as in Example 2. The composition obtained was placed in a mold and then vibrated. The vibration was performed from 1 minute after the start of charging. The vibrating mold was left at room temperature. After 30 minutes of standing at room temperature, foaming was completed. Next, the mold was covered with a lid, and then the mold was placed in an oven whose curing temperature was set to 85 ° C. in advance. After 6 hours, the mold was taken out of the oven, the obtained inorganic foam was removed from the mold, and dried at 50 ° C. for 2 hours to obtain an inorganic foam.

Evaluation The appearance of broken cells on the decorative surface of the inorganic foams obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was visually evaluated. Further, the inorganic foam was cut into 3 cm square pieces, the weight thereof was measured, and the result was divided by the volume to obtain the density. The results of these evaluations are shown in Table 1.

[0037]

[Table 1]

[0038]

The structure of the method for producing an inorganic foam of the present invention is as described above, and it is possible to reduce the productivity of the inorganic foam having almost no bubble breakage on the surface and an excellent appearance and to make a new capital investment. It is possible to provide a method that can be easily manufactured without the need for The obtained inorganic foam is useful as a building material and the like.

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Claims (1)

[Claims] 1. A composition prepared by mixing a foaming agent consisting of (A) reactive inorganic powder, (B) alkali metal silicate, (C) water and (D) metal powder or hydrogen peroxide in a molding die. In the method for producing an inorganic foam which is filled with, and cured by heating, the composition is filled into a molding die immediately after preparation, and is set to a predetermined curing temperature before or before the foaming is started. A method for producing an inorganic foam, which is characterized in that it is placed in a heating device.