JPH0130779B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing an ultra-light calcium silicate molded body, which is particularly lightweight, has excellent strength, heat resistance, and toughness, and has no dust on the surface of the molded body, and is suitable for use as heat insulators and heat insulators. , relates to a method for producing an ultra-lightweight calcium silicate molded body suitable as a fireproof coating material, etc. [Conventional technology] Heat insulating materials with a bulk specific gravity of 0.2 or more,
There is a lightweight calcium silicate molded body used as a fireproof coating material, and its manufacturing method involves hydrothermally synthesizing calcium silicate hydrate crystals under high temperature and high pressure while stirring a slurry mainly made of CaO and SiO ₂ . A method of molding is known. That is, since the synthetic crystal hydrate becomes a bulky hollow spherical aggregate due to stirring during hydrothermal synthesis, a lightweight molded product can be obtained by molding this aggregate. By the way, if a molded body is obtained from such an aggregate alone, the strength of the molded body will be insufficient in terms of shape retention, so it is generally manufactured by adding and mixing reinforcing fibers such as asbestos. However, in recent years, asbestos is said to be a harmful substance to the human body and regulations on its use have been tightened, so various materials have been proposed as reinforcing materials in place of asbestos, and among these, mica is said to be effective. There is. [Problems to be Solved by the Invention] However, molded bodies obtained by conventional manufacturing methods cannot be said to have sufficiently high strength even when mica is used, and have the disadvantage that the surface has a lot of dust. Ta. In particular, if you attempt to obtain an ultra-light molded product with a bulk specific gravity smaller than conventionally available products, the strength will further decrease and surface dusting will be promoted, making it impossible to obtain a molded product with commercial value. Nakatsuta. [Means for Solving the Problems] The present inventors have conducted intensive research on a method for producing a calcium silicate molded body that is ultra-lightweight, has high strength, and has no dust and high surface hardness, and as a result, has developed a synthetic calcium silicate slurry. An ultra-lightweight calcium silicate molded body is produced by adding and mixing swellable mica made of a specific fluorine mica, molding and drying, and then firing or immersing and drying in a salt solution containing ions that inhibit the swelling properties of mica. We established a completely new manufacturing method and completed the present invention. In the present invention, a slurry of hydrothermally synthesized calcium silicate hydrate has the general formula W _a [A, B] _b [(C, D) ₄ O ₁₀ ] F ₂ (wherein, W has a coordination number of 12 A and B are each cations with a coordination number of 6, C and D are each cations with a coordination number of 4, a is a positive number of 1 to 1/3, and b is a positive number of 2.5 to 3.
indicates a positive number. ) Swellable mica made of fluorine mica,
0.1 to 100 per 100 parts by weight of calcium silicate hydrate
A method for producing an ultra-lightweight calcium silicate molded body with a bulk specific gravity of 0.1 or less (hereinafter referred to as "No. 1), and a slurry of hydrothermally synthesized calcium silicate hydrate having the general formula W _a [A, B] _b [(C, D) ₄ O ₁₀ ] F ₂ (wherein, W is a cation with a coordination number of 12, A and B are each a cation with a coordination number of 6, C and D are each a cation with a coordination number of 4, a is a positive number from 1 to 1/3, and b is a positive number. 2.5～3
indicates a positive number. ) Swellable mica made of fluorine mica,
0.1 to 100 per 100 parts by weight of calcium silicate hydrate
After adding and mixing in parts by weight, molding and drying,
A method for producing an ultra-light calcium silicate molded body with a bulk specific gravity of 0.1 or less (hereinafter referred to as "second manufacturing method"), which comprises soaking the molded body in a salt solution containing ions that inhibit the swelling properties of mica and then drying it. ”). The present invention will be explained in detail below. In the ultra-lightweight calcium silicate molded article produced by the present invention, the mica having the specific composition serves to bind together the spherical aggregates of calcium silicate hydrate. For this reason, the calcium silicate hydrate becomes difficult to separate from the molded body, resulting in less dusting and increased strength. In addition, conventionally, when producing calcium silicate molded bodies, press molding is usually performed in order to increase the strength by bonding particles together, but in the present invention, as described above, calcium silicate water Pressing is not necessarily necessary since the compound particles are strongly bonded to each other via mica. If it is not pressed, it will not be compressed that much, resulting in an even lighter molded product. In the method of the present invention, first, a slurry of calcium silicate hydrate is prepared by hydrothermal synthesis, and swellable mica having the above-mentioned specific composition is added to this slurry. Calcium silicate hydrate produced by hydrothermal synthesis is extremely advantageous for the present invention because it becomes bulky and lightweight when molded and dried. Hydrothermally synthesized calcium silicate hydrate can be easily obtained by hydrothermally reacting silicic acid and calcareous raw materials using an autoclave equipped with a stirrer. As for the type of calcium silicate hydrate, xonotrite type or tobermorite type ones are preferable because they have good heat resistance and are easy to manufacture. The swellable mica added to the slurry of calcium silicate hydrate has the general formula W _a [A, B] _b [(C, D) ₄ O ₁₀ ] F ₂ (where W is an cation with a coordination number of 12). ions, A and B are each cations with a coordination number of 6, C and D are each cations with a coordination number of 4, a is a positive number of 1 to 1/3, and b is a positive number of 2.5 to 3.
indicates a positive number. ) A material made of fluorine mica is used. In the above general formula, W is Na ⁺ , Li ⁺ , A is Mg ²⁺ , Fe ²⁺ , Ni ²⁺ , Mn ²⁺ ,
Al ³⁺ , Fe ³⁺ , Li ⁺ , and as C and D, Si ⁴⁺ , Ge ⁴⁺ , Al ³⁺ , Fe ³⁺ ,
B ³⁺ compounds are preferable, and fluorine tetrasilicon mica compounds in which C and D are Si are particularly preferable. Specific examples of these include those listed in Table 1 below. Such mica adsorbs water between its layers, exfoliates and swells, forming extremely fine thin layers. Note that W (in Table 1, Li and W, which are interlayer ions)
Na) can be exchanged with other ions.

[Table] When adding mica to the slurry of calcium silicate hydrate, mixing is facilitated by swelling the mica in water in advance and adding it to the slurry. The amount of mica added is 100% calcium silicate hydrate.
The amount is 0.1 to 100 parts by weight. If the amount of mica exceeds 100 parts by weight, shrinkage will be large and cracks will occur in the molded product. In addition, the amount of mica added
If the amount is less than 0.1 part by weight, the effect is low. It is preferable to add mica in an amount of at least 1 part by weight. The mixed slurry thus prepared is then molded and dried by a known method to obtain a dry molded product. In the present invention, the swellable mica added to the slurry is exfoliated between its layers to become extremely fine particles, which enter between the calcium silicate hydrate particles. Then, in the drying process, the mica fine particles strongly bond with each other, and at this time, they also become strongly bonded with the calcium silicate hydrate particles.
It is presumed that excellent strength, toughness, etc. will be developed. In the first manufacturing method of the present invention, this dry molded body is then fired at 300 to 500°C. By this firing, water molecules between the layers of mica are separated, and even if the molded body is placed in water again, the mica will not swell. If the firing temperature is too high, dehydration of calcium silicate hydrate and/or collapse of the crystal structure of mica, etc.
If it is too low, it will cause undesirable phenomena.
Moisture between the layers cannot be separated, and the mica may swell again in water. Moreover, long-term heating is required, which is not efficient. In the present invention, the firing temperature is set at 300 to 500°C in consideration of energy consumption, operation management, etc. In the second manufacturing method of the present invention, the dried molded body is immersed in an aqueous solution of water-soluble salts containing ions that inhibit the swelling properties of mica, and after ion exchange, is dried again. This second manufacturing method does not employ a firing process, does not require firing equipment, and does not require firing energy, and has high industrial value. Ions that inhibit the swelling properties of mica are ions that replace ions between the mica layers and prevent water molecules from being taken between the layers again. For example, when the mica is the swellable fluorine tetrasilicon mica listed in Table 1 above, the ions that inhibit this swelling property include:
Examples include potassium ion, ammonium ion, strontium ion, barium ion, iron ion, aluminum ion, and the like. Further, as water-soluble salts containing these ions, water-soluble salts among chlorides, sulfates, nitrates, carbonates, etc. can be used. Among these salts, potassium chloride, potassium nitrate, ammonium chloride, ammonium nitrate, potassium nitrate, and ammonium nitrate are particularly preferred because they are easily water-soluble and easily available. In addition, in the method of the present invention, reinforcing fibers may be included in the mixed slurry used for molding, if necessary. By containing reinforcing fibers, properties such as bending strength and toughness can be improved. Various known reinforcing fibers can be used as this reinforcing fiber, but in cases where heat resistance is particularly required, such as when the manufactured body is intended to be used as a heat-resistant insulation material or a fire-resistant coating material. When doing so, it is desirable to use heat-resistant fibers. Specific examples of the heat-resistant fiber include fibers such as asbestos, glass fiber, SiC fiber, potassium titanate fiber, and alumina fiber. If heat resistance is not required, pulp, various synthetic fibers, etc. can also be used, but the molded product according to the present invention is often used for applications that effectively utilize the heat resistance of calcium silicate hydrate. , it is advantageous to use heat-resistant fibers. In particular, in the first manufacturing method of the present invention, it is desirable to use heat-resistant fibers as the reinforcing fibers, since the molded body undergoes a step of heating and firing after drying. The amount of reinforcing fibers is not particularly limited, and may be selected appropriately taking into consideration the strength properties required of the resulting calcium silicate molded product.
Naturally, if the molded article does not require particular strength, reinforcing fibers may not be added. In addition, in order to produce a calcium silicate hydrate-based molded article containing reinforcing fibers, the reinforcing fibers are mixed into the calcium silicate hydrate slurry as described above, but the order in which the fibers are added to the slurry is such that mica is added. It doesn't matter if it's before or after. [Examples of the Invention] The present invention will be explained in more detail below using Examples and Comparative Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Example 1 Slaked lime and powdered silica sand were mixed at a CaO/SiO ₂ molar ratio of 1.0, water was added, and the mixture was reacted in a stirring autoclave under saturated steam pressure at 200°C to obtain a calcium silicate hydrate slurry. Swellable mica (NA-TS (HG) manufactured by Topy Industries, Ltd.) and reinforcing fiber (glass fiber in this example) were mixed into this slurry in the proportions shown in Table 2. This was poured into a mold, dried, and fired at 500°C for 3 minutes to produce a calcium silicate hydrate molded body. Various physical properties of the obtained molded body were measured. The results are shown in Table 2.

[Table] Example 2 A molded body was produced in the same manner as in Example 1 except that the dry molded body obtained with the formulation No. 4 of Example 1 was subjected to firing treatment under the treatment conditions shown in Table 3. Various physical properties of this molded body were measured. The results are shown in Table 3. Further, the molded body after the firing treatment was immersed in water for 24 hours and the state of swelling was observed. The results are also shown in Table 3.

[Table] ●: No abnormality.
Example 3 A calcium silicate hydrate slurry was prepared in the same manner as in Example 1, and the same mica and glass fibers used in Example 1 were mixed in the formulation shown in Table 4. After pouring this into a mold and drying it, add 5% potassium chloride.
A molded article was produced by immersing it in an aqueous solution for 5 minutes, ion-exchanging it, and then drying it again. Table 4 shows the various physical properties of the obtained molded product and the observation results of its properties after being immersed in water for 24 hours.

[Table] Example 4 After drying the molded product obtained with the formulation No. 11 of Example 3, it was immersed for 5 minutes in a 5% aqueous solution of various salts listed in Table 5, and after ion exchange, it was re-dried and molded. manufactured a body. Table 5 shows the observation results of the dusting of the obtained molded product and its properties after being immersed in water for 24 hours.

[Table] From Tables 2 to 5, it is clear that according to the method of the present invention, ultra-lightweight molded bodies with excellent properties are produced. Comparative Example 1 Slaked lime and powdered silica sand were mixed at a CaO/SiO ₂ molar ratio of 1.0, water was added, and the mixture was reacted in a stirring autoclave under saturated steam pressure at 200°C. 3% glass fiber was added to this, mixed, molded, and dried to produce a molded product. The obtained compact has a bulk specific gravity
It had a bending strength of 0.080 (-), a bending strength of 0.22 Kgf/cm ² and a lot of dust. [Effects of the Invention] As detailed above, according to the method for producing an ultra-lightweight calcium silicate molded body having a bulk specific gravity of 0.1 or less of the present invention, calcium silicate hydrate particles are bonded via mica particles having a specific composition. Therefore, it is possible to easily produce a molded article with high properties, which is extremely lightweight, has high strength, has excellent heat resistance and toughness, and has little dusting, and is extremely useful industrially as various constituent materials.

Claims (1)

[Claims] 1. A slurry of hydrothermally synthesized calcium silicate hydrate has the general formula W _a [A, B] _b [(C, D) ₄ O ₁₀ ] F ₂ (where W is a A and B are each cations with a coordination number of 6, C and D are each cations with a coordination number of 4, a is a positive number of 1 to 1/3, and b is a positive number of 2.5 to 1/3. 3
indicates a positive number. ) Swellable mica made of fluorine mica,
0.1 to 100 per 100 parts by weight of calcium silicate hydrate
A method for producing an ultra-lightweight calcium silicate molded body having a bulk specific gravity of 0.1 or less, which comprises adding and mixing parts by weight, then molding, drying the molded body, and then firing at 300 to 500°C. 2 A slurry of hydrothermally synthesized calcium silicate hydrate is added with the general formula W _a [A, B] _b [(C, D) ₄ O ₁₀ ] F ₂ (where W is a cation with a coordination number of 12). , A and B are each a cation with a coordination number of 6, C and D are each a cation with a coordination number of 4, a is a positive number of 1 to 1/3, and b is a positive number of 2.5 to 3.
indicates a positive number. ) Swellable mica made of fluorine mica,
0.1 to 100 per 100 parts by weight of calcium silicate hydrate
After adding and mixing in parts by weight, molding and drying,
1. A method for producing an ultra-lightweight calcium silicate molded body having a bulk specific gravity of 0.1 or less, which comprises immersing the molded body in a salt solution containing ions that inhibit the swelling properties of mica, and then drying the molded body.