JPH0437005B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is directed to kirucoanite (9CaO.6SiO _2.0 ~ 1H ₂ O) or P
The present invention relates to a method for producing a highly heat-resistant calcium silicate composition containing Phase (8CaO.5SiO ₂ ) as a main component. Conventionally, industrially manufactured calcium silicate insulation materials or fireproof insulation materials are:
The main component is tobermorite (5CaO・6SiO ₂・5H ₂ O), and the other is xonotlite (6CaO・6SiO ₂・
It can be classified into two types: those whose main component is H ₂ O). When materials whose main component is tobermorite are heated above 700℃, they transform into wollastonite, causing a significant change in volume, causing cracks in the product, or
The temperature at which it can be used is limited to around 650°C, as this will cause it to collapse. On the other hand, those whose main component is xonotlite have higher heat resistance than those whose main component is tobermorite, and they also convert wollastonite (β-CaO SiO ₂ ), it has a low heating shrinkage rate and good heat resistance, so it can be used as a heat insulating material,
Widely used as a fireproof insulation material and fireproof building material. However, when used at high temperatures such as 1000℃ or higher, wollastonite crystals sinter and
This can lead to cracks and collapse, causing heat insulating materials, fireproof insulation materials,
It will no longer be able to maintain its function as a fireproof building material. Circoanite is conventionally known as a calcium silicate composition that can be used at temperatures of 1000°C or higher. This kirucoanite is transformed into rankinite (C ₃ S ₂ ) by topotactic at a temperature of 900-1000℃.
The change in volume at that time is also extremely small. Usually, kilcoaite is produced by forming xonotlite or phosciatite from silicate raw material and calcareous raw material, and by reacting this xonotlite or phosciatite at high pressure of about 1000 Kg/cm ² at 350°C or higher, or by reacting silicic raw material and calcareous raw material by high pressure reaction of about 1000 Kg/cm2. It is produced by firing at ~1500°C to form γ-C ₂ S and hydrothermally reacting this γ-C ₂ S with a silicate raw material. However, the former method requires a high-pressure reaction, and the latter method requires
The presence of impurities such as Cr ₂ O ₃ makes it difficult to form γ-C ₂ S, so it is still insufficient as an industrial production method, as it requires purification of raw materials and a firing process. be. The present inventors have made extensive studies to provide an industrially advantageous method for producing kirucoanite _or P-Phase _.
Circoanite or P-
We discovered that Phase can be manufactured,
The present invention has now been completed. That is, the gist of the present invention is that α-C ₂ S hydrate formed from a silicate raw material and a calcareous raw material,
The molar ratio of CaO component and SiO ₂ component (CaO/SiO ₂ ) is
A hydrothermal reaction is carried out under the conditions of 1.2 to 1.8 to produce chircoanite (9CaO 6SiO ₂ 0 to 1H ₂ O) or P-
The present invention relates to a method for producing a highly heat-resistant calcium silicate composition, which is characterized by obtaining a calcium silicate composition containing Phase (8CaO.5SiO ₂ ) as a main component. The present invention will be explained below. In the present invention, first, an α-C ₂ S hydrate is formed from a silicate raw material and a calcareous raw material. The α-C ₂ S hydrate referred to in the present invention refers to the α-C 2 S hydrate described by Udagawa et al.
The crystal structure of α-Ca ₂ (SiO ₃ OH) OH as explained in Proceedings of the Ceramics Association Annual Conference, 90, (1981) is shown. Examples of silicic raw materials include crystalline silicic raw materials such as silica stone and silica sand, naturally occurring silicic acid powders such as silica, white clay, and diatomaceous earth, and amorphous silicic raw materials such as white carbon and dust generated during the production of ferrosilicon. Can be used. In addition, as calcareous raw materials, quicklime, slaked lime,
Carbide slag and the like, particularly quicklime, can be suitably used. As a method for forming α-C ₂ S hydrate, for example,
The following methods may be mentioned. (1) A siliceous raw material and a calcareous raw material are dispersed in water so that the molar ratio of CaO/SiO ₂ is 1.2 to 2.3 to obtain a suspension. At that time, the total amount of water used is 5 to 40 times the solid content by weight. Next, this suspension was placed in an autoclave.
A method of forming an α-C ₂ S hydrate by reacting at a temperature of 150 to 230°C and a pressure of 5 to 30 Kg/cm ² G for about 1 to 20 hours. In this method, the siliceous raw material is
It is preferable to use one that is crystalline and has a Blaine value of 45500 cm ² /g or less, preferably 1000 to 4500 cm ² /g, particularly preferably 2000 to 4000 cm ² /g. Amorphous or Blaine value 5000cm ² /g
Larger crystalline siliceous raw materials have higher dissolution rates and C-C2S without forming α- _C2S hydrates.
Since S-H is generated, it is easy to transform into a stable hydrate such as xonotlite. Therefore, even if this is subjected to a hydrothermal reaction using the method described below, the desired kircoaite or P-Phase cannot be obtained. Note that the plane value is a value measured in accordance with JIS R5201 (blane air permeation device). (2) Add appropriate silicic raw materials to β-C ₂ S (β-2CaO・SiO ₂ ) so that the molar ratio of CaO/SiO ₂ is 1.2 to 2.0, and the total amount of water is 5 to 40% of the solid content. Add twice the weight of water to obtain a suspension. This suspension was heated in an autoclave for 150-230 min.
^α-
Method of forming _C2S hydrate. β-C ₂ S used as a raw material in this method is
For example, it can be easily obtained by the following method. Silicate raw material and calcareous raw material are combined into CaO/SiO ₂
This was dispersed in water with a total water content of 5 to 40 times the solid content, and heated in an autoclave at 200 to 300℃ for 15 minutes.
React at ~80Kg/cm ² G for 1 to 20 hours to form Hillebrandite (2CaO・SiO ₂・H ₂ O),
Next, this is dried and heated to 1000 ml in an electric furnace etc.
A method to obtain β-C ₂ S by quenching after firing at a temperature of ~1500°C. Powders of siliceous raw materials and calcareous raw materials are mixed with CaO/
A method of obtaining β-C ₂ S by mixing SiO ₂ at a molar ratio of 2.0, firing this mixture at a temperature of 1200 to 1500°C in an electric furnace, etc., and then rapidly cooling it. In this method, in order to stably obtain β-C ₂ S, a stabilizer such as chromic oxide is usually added to the mixture. Even if C ₂ S is subjected to a hydrothermal reaction using the method described below, it is difficult to obtain the desired kirucoanite or P-Phase, so in the present invention, it is preferable not to use the above-mentioned stabilizers. . The α-C ₂ S hydrate formed as described above has a CaO/SiO ₂ molar ratio of 1.2 to 1.8.
Preferably, by hydrothermal reaction under conditions of 1.4 to 1.7, it is possible to easily convert kirucoanite or P-
A calcium silicate composition containing Phase as a main component can be obtained. The conditions for the hydrothermal reaction vary depending on the method of forming the α-C ₂ S hydrate, but are usually 150 to 230°C, 5 to
1 to 20 hours at 30Kg/cm ² G, preferably 180 to
It may be carried out at 220° C. and 10 to 24 Kg/cm ² G for 2 to 10 hours. The molar ratio of CaO/SiO ₂ in α-C ₂ S hydrate is 1.7.
In this case, a silicate raw material is added to the α-C ₂ S hydrate at a molar ratio of CaO/SiO ₂ of 1.2 to 1.8, preferably 1.4 to 1.7, and the hydrothermal reaction is carried out within the above range. do it. At this time, the silicic acid raw material to be added may be either crystalline or amorphous. Further, there is no particular restriction on the Blaine value of crystalline materials. The calcium silicate composition containing kirkoanite or P-Phase as a main component obtained by the method described above exhibits excellent heat resistance with little weight loss even at a temperature of 1200°C. The calcium silicate composition containing Kilcoanite or P-Phase of the present invention as a main component is prepared by a known method,
For example, after dehydration molding with a filter press,
A molded article with excellent heat resistance can be obtained by drying or drying after steam curing. EXAMPLES The present invention will be further specifically explained with reference to Examples below. Example 1 100 parts of quicklime (96.2% CaO) was digested by adding warm water, and then silica stone (96.4% SiO ₂ ) with a Blaine value of 2960 cm ² /g was added so that the molar ratio of CaO / SiO ₂ was 1.5.
After adding 71 parts of water, water was added so that the total amount of water was 20 times the weight of the solid content to obtain a suspension. This suspension was placed in an autoclave at 200℃ for 15 minutes.
The reaction was stirred for 1 hour under the condition of Kg/cm ² G. Subsequently, the stirring reaction was continued for an additional 4.5 hours under the same conditions. After the reaction, the reaction products at 1 hour and 5.5 hours were dried at 150°C for 8 hours, and powdered.
Its components were identified by X-ray diffraction. In addition, the weight loss rate (TG) at 1200°C was measured by differential thermal analysis. The results are shown in Table 1. Comparative Example 1 A stirring reaction was carried out in the same manner as in Example 1 except that silica stone having a Blaine value of 4830 cm ² /g was used instead of silica stone having a Blaine value of 2960 cm ² /g. The components of the reaction product 1 hour and 5.5 hours after the reaction were as shown in Table 1. Comparative Example 2 A stirring reaction was carried out in the same manner as in Example 1 except that the molar ratio of CaO/SiO ₂ was changed to 2.0 instead of 1.5. The components of the reaction product 1 hour and 5.5 hours after the reaction were as shown in Table 1.

[Table] Example 2 100 parts of quicklime (96.2% CaO) was digested by adding hot water _, and silica stone ( ^96.4 % SiO ₂ )of
After adding 53 parts, water was added so that the total amount of water was 30 times the weight of the solid content to obtain a suspension. This suspension was heated to 40Kg/cm ² G in an autoclave.
The mixture was stirred and reacted for 5 hours under a water vapor pressure of 500 mL to obtain a calcium silicate hydrate consisting of hillebrandite. This hydrate was dried at 150°C for 8 hours and ground.
Next, this pulverized product was calcined in an electric furnace at 1000°C for 5 hours, and then rapidly cooled to obtain β-C ₂ S. Silica stone with a Blaine value of 4830 cm ₂ ^/ g ₍ 96.4%
18 parts of SiO ₂ ) was added, and the total amount of water was adjusted to the solid content.
Water was added to make the suspension 20 times the weight to obtain a suspension. This suspension was placed in an autoclave at 200℃ for 15 minutes.
The stirring reaction was carried out under the condition of Kg/cm ² G. The components of the reaction product at 1 hour and 5.5 hours after the reaction were identified in the same manner as in Example 1. The results are shown in Table 2. Comparative Example 3 In Example 2, the total water amount was 20% of the solid content without adding silica to the obtained β-C ₂ S.
A stirring reaction was carried out in the same manner as in Example 2, except that a suspension obtained by adding only water to double the weight was used. The components of the reaction product at 1 hour and 5.5 hours after the reaction were as shown in Table 2.

[Table] Example 3 To the reaction product obtained by reacting for 5.5 hours in the same manner as in Comparative Example 1 (solid content 153 parts, water 3060 parts),
After adding 18 parts of silica stone (96.4% SiO ₂ ) with a Blaine value of 4830 cm ² /g so that the molar ratio of CaO / SiO ₂ was 1.5, the mixture was heated in an autoclave at 225°C and 26 Kg/cm ² G. After standing and curing for 12 hours, a hardened calcium silicate body was obtained. This cured product was dried at 150° C. for 8 hours and then ground into powder, and the components were identified in the same manner as in Example 1. The results are shown in Table 3. Example 4 To the reaction product obtained by reacting for 5.5 hours in the same manner as in Comparative Example 3 (solid content 153 parts, water 3060 parts),
After adding 18 parts of silica stone (96.4% SiO ₂ ) with a Blaine value of 4830 cm ² /g so that the molar ratio of CaO / SiO ₂ was 1.5, a cured product was obtained in the same manner as in Example 3, and its components were identified. did. The results are shown in Table 3.

[Table] In Tables 1 to 3 above, α, γ, Xo,
Q, CH, Ki and P represent the following meanings. α: α- _C2S hydrate _{γ :} γ-C2S means that a trace level has been detected.

Claims (1)

[Claims] 1. α-C ₂ S hydrate formed from silicic raw materials and calcareous raw materials under conditions where the molar ratio of CaO component and SiO ₂ component (CaO/SiO ₂ ) is 1.2 to 1.8. By hydrothermal reaction, kirucoanite (9CaO・6SiO ₂・0～
1H ₂ O) or P-Phase (8CaO・
A method for producing a highly heat-resistant calcium silicate composition, the method comprising obtaining a calcium silicate composition containing 5SiO ₂ ) as a main component. 2. The manufacturing method according to claim 1, wherein the α-C ₂ S hydrate is obtained by hydrothermally reacting a crystalline silicate raw material and a calcareous raw material with a Blaine value of 4500 cm ² /g or less.