JPH02279549A - Production of calcium silicate-based molded body - Google Patents

Abstract

PURPOSE:To improve strength, heat resistance, heat insulating and retaining property and shock resistance by adding gamma-dicalcium silicate to powdery starting material contg. a siliceous substance and a calcareous substance and by hardening them by a reaction under steam at high temp. and pressure. CONSTITUTION:CaCO3 is blended with SiO2 so that the blend has a compsn. giving 2CaO.SiO2 and the blend is calcined at >=1,400 deg.C and repidly cooled to obtain gamma-dicalcium silicate (gamma-C2S). From 5 to 82 wt.% (gamma-C2S) and 1 to 5wt.% resin powder as required are added to powdery starting material contg. a siliceous substance such as silica powder and a calcareous substance such as quick lime They are uniformly mixed without adding water and the mixture is filled into a mold for molding and hardened by a reaction under steam at high temp. and pressure, e.g., at 180 to 200 deg.C for 8 to 15hr. A flat or cubic meshy reinforcing member is previously fixed in the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a calcium silicate molded body used as, for example, a building material, a heat-retaining material, or a fire-resistant heat-insulating material.

<Prior Art> Conventionally, calcium silicate molded bodies used as, for example, building materials, heat-insulating materials, or fire-resistant and heat-insulating materials have been obtained by the following method.

■ Siliceous raw materials and calcareous raw materials are kneaded with water to form a slurry, which is then made into a sheet using a paper-making machine, which is then hardened by producing calcium silicate hydrate under high temperature and high pressure steam pressure. Method. (This method is used to manufacture thin materials with a thickness of about 15 cm or less.
The bulk specific gravity of the obtained molded product is about 0.8 to about 1.5, and the bending strength is 80 kg/d to 150 kg/d.
There is cj te. ) ■ A method in which siliceous raw materials and calcareous raw materials are kneaded with water to form a slurry, which is press dehydrated and molded, and then cured under high-pressure steam as in (■) after demolding. In this case, a part of the silicic acid raw material is replaced with N13 to an amorphous silicic acid raw material such as diatomaceous earth or silica hume, and the mixed slurry is heated at 90 to 100°C under atmospheric pressure to form a bulky swollen gel. After that, by press water molding, a product with a lower bulk specific gravity than in the case of (2) above can be obtained. (The molded product obtained by this method has a bulk specific gravity of 0.1 to 1.0 and a bending strength of 1.0 to 100 kg/cli, and can be obtained in a wide range of qualities. .1~0
．． Type 5 has excellent heat insulation properties and is used as a heat insulating material, fireproofing material, and coating material.
．． 0 is used as a building material and as a large-sized fireproof insulation material. ) ■ Mix silicic acid raw materials and calcareous raw materials with water, react in a slurry state under high temperature and high pressure steam to generate calcium silicate hydrate, and then add reinforcing fibers or heat-resistant materials as necessary. A method in which the inorganic filler is kneaded, press-molded, and dried. (The molded product obtained by this method has a bulk specific gravity of 0.1 to 0.5 and a bending strength of 2 to 20 kg.
/csl and is used as a heat insulating material and fireproof coating material. ) However, in the conventional methods (so-called wet methods) mentioned above, it is necessary to mix the raw materials with water to form a slurry or gel, and then cure it under high-temperature, high-pressure steam.

In addition, the conventional method not only complicates the production process by performing press dehydration, but also causes problems such as shrinkage of the product during the process.

For this reason, various methods have been developed for molding the powder in a dry powder state.

For example, Japanese Patent Publication No. 42-658 and Japanese Patent Publication No. 42-65
No. 9 discloses a technique in which waste carbide lime is used in a dry state together with silicic acid powder, press-molded, and then treated with frA steam in an autoclave.

In addition, Japanese Patent Publication No. 61-25672 discloses that after mixing a silicic acid raw material and a calcareous raw material without adding water, the mixture is filled into a mold as it is and reacted under high temperature and high pressure steam. A technique (so-called dry method) for obtaining a molded article containing calcium silicate hydrate by curing is disclosed.

<Problems to be Solved by the Invention> However, in the conventional so-called dry method, there is a problem that the strength of the obtained molded product is significantly lower than that in the wet synthesis method.

(For example, it is possible to obtain a product with a bulk specific gravity of 0.3 to 1.0, which is comparable to the wet method, but if the bulk specific gravity is 1.0, the bending strength is only about 20 to 30 kgIcd. Furthermore, when using a product obtained by dry synthesis as a building material, there is a problem that the product is easily damaged during handling.

In view of the above-mentioned circumstances, the present invention provides a method for producing a calcium silicate molded body that does not lack strength, is easy to produce, and is suitable for use in, for example, building materials, various heat-retaining materials, and fire-resistant and heat-insulating materials. The purpose is to

<Means for solving am> In order to achieve the above object, the method for producing a calcium silicate molded body of the present invention has a structure in which a powder raw material containing silicic acid and calcareous material is mixed with water in a powder state. A method for producing a calcium silicate molded body, in which the calcium silicate molded body is uniformly mixed without addition of powder, and then cured by reaction under high temperature and high pressure steam, characterized by adding γ-type dicalcium silicate to a part of the powder raw material. .

Below, the configuration of the present invention will be explained in detail.

Here, as the powder raw material containing silicic acid and calcareous material in the present invention, a powdered material obtained by adding and mixing a known silicic acid raw material and calcareous raw material can be used as in the past. For example, as the silicic acid raw material, silica powder can be mainly used, and depending on the desired specific gravity, pearlite with a low bulk specific gravity, diatomite which is an amorphous silicic acid raw material, silica hume, white carbon, etc. etc.,
It is also possible to replace part or all of the silica powder with W.

Also, for example, as a calcareous raw material, quicklime is used.

Examples include slaked lime and cement.

It is more suitable for these raw material powders to have a uniform particle size for uniform mixing.

In the present invention, by adding γ-type dicalcium silicate to a part of the powder raw material containing the silicic acid and calcareous substances, the strength of the obtained molded body can be improved.

Here, γ-type dicalcium silicate is a mixture of calcium carbonate and silicon dioxide powder with a composition of 20aO3iO2, and 140
It is a powder having an orthorhombic olivine-type crystal form, which is obtained by firing to 0° C. or higher and then slowly cooling it.

This γ-type dicalcium silicate (72CaO・SiO□; hereinafter referred to as “γ
-C2S'', ) is shown in Table 1.

Table 1 As shown in Table 1, γ-C2S is generally Cab.

The main component is Si, and further AN, 03. Fθ, O,,
MgO.

Contains trace components such as Naρ, 20, etc. This ff
Of the 1ffi components, when obtaining a xonotrite calcium silicate molded body, the AN20° component accounts for 3 of the total.
1! It is desirable that the amount is less than i%. This is Al2O
This is because if 3 is 3% by weight or more, a tobermorite-based molded body will be formed. In addition, # of the obtained molded body
4. In order to prevent a decrease in thermal properties, it is desirable that Na2O and K2O be each at 2.0% by weight or less of the total weight.

In addition, the amount of γ-C2S added to the powder raw material mainly composed of silicic acid and calcareous material is 5 to 82% by weight of the total.
It is appropriate to

This is because if it is less than 5% by weight, the effect of improving the strength of the obtained molded product is weak, and if it is more than 80% by weight,
This is because the Cab/Sin molar ratio is not appropriate. For example, when obtaining a xonotrite-based molded body, C
The ab/5in2 molar ratio is preferably 0.8 to 1.2, but when the CaO/S i O molar ratio is 1.2,
γ-C and S can be added in an amount of about 81.5%.

Further, by uniformly adding and mixing reinforcing materials such as fibrous raw materials or inorganic fillers to the powder raw material containing silicic acid and calcareous materials, the heat resistance of the obtained molded product is improved and , to prevent the occurrence of microcracks that occur during manufacturing.

Here, as the above-mentioned wA fibrous raw material, for example, organic TA fibers such as pulp and rayon, or inorganic fibers such as alkali-resistant glass fibers and carbon fibers can be used. It is preferable to use one that can be mixed and dispersed uniformly, and it is preferable to use one that can be mixed and dispersed uniformly. Further, the amount of the fibrous raw material added is preferably 1 to 5% by weight based on the mixed dispersion of the powdered raw material containing silicic acid and calcareous material.

Further, as the inorganic filler, conventionally used materials such as fibrous wollastonite or mica powder can be used.

These fibrous raw materials or inorganic fillers can be added to Keil! l
In order to add and mix it to the powder raw material containing limestone and limestone, a known mixing method that achieves a uniformly mixed and dispersed state may be used.

Further, a powder raw material containing the above-mentioned silicic acid and calcareous material,
When filling the mixture with γ-C2S, a reinforcing member may be included as necessary. This reinforcing member is either placed in advance in the molding frame, or is placed sequentially when filling the dry waste compound, and is made of, for example, cotton-like metal such as iron or stainless steel IK. Continuous long fibers having a length of about 20 to 30 M or more may be mentioned, such as fibers, alkali-resistant glass LA fibers, and carbon fibers. In addition, when providing this reinforcing member, it may be formed in a planar mesh shape and provided in a single layer or in multiple layers depending on the thickness of the board to be manufactured, or it may be formed in a three-dimensional mesh shape depending on the board thickness. A molded product may be placed as appropriate.

There are two main methods for arranging this reinforcing member within the formwork.

(1) The first method is to fix the above-mentioned planar or three-dimensional mesh reinforcing member to a molding mold, and charge it with uniformly mixed powder raw materials.

■ As a second method, first, a predetermined amount of a uniformly mixed powder raw material is charged into a forming mold, and on top of this charged powder raw material, a linear body is assembled in a lattice shape, for example. A method of placing a reinforcing member such as, and then charging and filling the remaining powder raw material on top of the reinforcing member.

Furthermore, as a reinforcing member, in addition to those formed from linear bodies9, for example, an expanded metal lath formed from a metal plate used as a mortar base etc. into a mesh shape, or a metal plate with a large number of holes provided therein can be used. be able to.

This M-strength member preferably has a mesh opening of about 5 m or more so that filling with the powder mixture is not difficult or, in the case of a sheet, so that delamination does not occur.

The powder raw material can be charged uniformly into the mold by applying vibration using a known method such as a vibrator.

As the above-mentioned molding mold, any known mold that can be used repeatedly in 14-fuchi high-pressure steam may be used, and for example, a mold made of stainless steel is preferable from the viewpoint of corrosion resistance. It is also possible to apply polytetrafluoroethylene (trade name: Teflon) to the inner surface of the molding frame (B) to make demolding easier.

Furthermore, by forming an uneven pattern on the inner surface of the molding frame in advance, it becomes possible to provide the molded article with a desired uneven pattern.

As mentioned above, a dry powder mixture of silicic acid and calcareous powder materials to which γ-C2S has been added is placed in a mold for molding and heated in a well-known predetermined autoclave with high-temperature, high-pressure steam. The desired calcium silicate hydrate can be produced under the following predetermined reaction conditions.

The above reaction conditions can be broadly classified into two types.

■ As the first reaction condition, when producing tobermorite-based calcium silicate hydrate (5Ca0.6SiO2-5H,0) (mainly for building materials, heat-resistant concentration 650°C), the CaO/SiO molar ratio is approximately 0.8 and 180℃
It is preferable to react for 8 to 12 hours under a vapor pressure of (about 10 kg/cd).

■ As the second reaction condition, when producing xonotrite calcium silicate hydrate (6CaO-6SiO2.H,O) (mainly for high temperature refractory insulation materials; W4 thermal temperature 1
000℃), the Cab/5in2 molar ratio is approximately 1,
10~ under steam pressure of 200℃ (approximately 15kg/c+/)
It is preferable to react for 15 hours.

The calcium silicate molded product containing γ-C8 obtained in this way has sufficient heat resistance, heat insulation and impact resistance, and is suitable for use as, for example, fireproof insulation materials, various building materials, etc. It is.

Example of implementation Examples of the present invention will be described in detail below.

Example White carbon, silica sand, γ-C, S, slaked lime ff!
The mixture was blended as shown in Table 2, and 10% by weight of wollastonite as a #4 thermal filler and 1.51% by weight of alkali-resistant glass fiber as a wA fibrous material were mixed without adding water. This mixture was filled into a 30 x 100 x 30 (1 m) mold, and the mold was cured in an autoclave at 200°C for 15 hours to obtain a xonotlite calcium silicate molded body. , bending strength, compressive strength, and heat shrinkage rate at 1000°C were measured.

Comparative Example Comparison 6i11 without adding γ-C2S, Examples 1-
In order to adjust the specific gravity in the same manner as in Example 4, the amount of white carbon added was varied and the same procedure as in Example was carried out.

These results are shown in Table 2.

// /'/'' / // / From the results in Table 2, the molded product according to this example was superior in both bending strength and compressive strength compared to the comparative example.

<Effects of the Invention> As described above in detail with Examples, according to the present invention, a high-strength calcium silicate molded body can be obtained by a dry synthesis method due to the addition of γ-type dicalcium silicate. be effective.

Claims (1)

[Claims] 1) A calcium silicate molded body in which powder raw materials containing silicic acid and calcareous materials are uniformly mixed in a powder state without adding water, and then reacted and hardened under high temperature and high pressure steam. A method for producing a calcium silicate molded body, characterized in that γ-type dicalcium silicate is added to a part of the powder raw material. 2) The method for producing a calcium silicate molded body according to claim 1, wherein a resin powder is added to a part of the powder raw material to which the γ-type dicalcium silicate is added. manufacturing method.