JPH01246122A - Spherical particle of xonotlite for molding material and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject material having small apparent specific gravity and improved strength and formability by the hydrothermal synthetic reaction of a specific slaked lime and silica powder in the presence of water. CONSTITUTION:Slaked lime having an Al2O3 content of <=0.1wt.% is mixed with silica powder having an Al2O3 content of 0.5-3wt.% at an SiO2/CaO molar ratio of 1.00. The obtained raw material is added with 5-15 times weight of water and subjected to hydrothermal synthetic reaction in an autoclave under stirring to obtain spherical particle of xonotlite having an apparent specific gravity of 0.15-0.17 and a double-layer structure composed of an inner core and an outer shell connected with each other in the form of a network through acicular xonotlite crystals. 100pts.wt. of a slurry containing said particle is mixed with 1-20pts.wt. of an emulsion of a polymer such as styrene-butadiene copolymer, 1-10pts.wt. of a reinforcing fiber and, as necessary, dispersing agent, expansion material, etc., the mixture is filled in a mold and compression molded and the product is dried at 100-180 deg.C to obtain a xonotlite molded article having a bulk specific gravity of 0.3-0.7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to zonotrite spherical particles having a bulk specific gravity of 0.3 to 0.8 and suitable as a molding material for building materials, and a method for producing the same.

[Prior art] Calcium silicate (usually tobermorite or xonotlite) produced by hydrothermal synthesis reaction while stirring in the presence of water is a lightweight and thermally stable substance, and this property can be used to produce high specific gravity. Caldium silicate molded bodies with a density of 0.3 or less are widely used as heat insulating materials and heat retaining materials.

In addition, an attempt to manufacture artificial wood by adding reinforcing fibers, latex, etc. to calcium silicate and molding it to a bulk specific gravity of 0.3 to 0.7 was proposed in (1) JP-A No. 60-24625, etc. has been done.

[Problems to be Solved by the Invention] Calcium silicate (usually xonotrite or tobermorite) is produced by a hydrothermal synthesis reaction, and a molded article is produced by molding this calcium silicate and then drying it. The previously proposed calcium silicate spherical particles have thin shells, and when used to produce molded products with a bulk specific gravity of 0.3 to 0.7, the shells may deform or break, causing the properties of the spherical particles to deteriorate. It will be damaged. Moreover, molding performance tends to deteriorate due to deformation and destruction, that is, water retention during molding tends to deteriorate.

[Means for Solving the Problems] The present invention relates to spherical zonotolite particles having a double shell structure, the inner shell and the outer shell of which are connected in a network shape by needle-like xonotrite crystals, and a method for producing the same. is.

The zonotolite spherical particles of the present invention are made by mixing slaked lime with an aluminum oxide content (hereinafter simply referred to as aluminum content) of 0.1% by weight or less and silica powder with an alumina content of 0.5% by weight or more and 3% by weight or less. It is obtained by carrying out a hydrothermal synthesis reaction in an autoclave while stirring in the presence of.

The zonotolite spherical particles obtained in this way are hard to deform or break when molded even though their apparent specific gravity is as light as 0.15 to 0.17, and the calcium silicate molded product has good moldability and high strength. can be manufactured.

It is not clear why xonotrite with a double shell is produced when the above raw materials are used, but when quicklime is used or silica stone containing 0.5% by weight or less of alumina is used, Only thin-shelled xonotlites are produced instead of double structures. Furthermore, if silica powder containing 3% by weight or more of alumina or an alumina component is separately added, the reaction time will only be delayed and the above-mentioned xonotrite will not be produced.

The slaked lime used in the present invention is commercially available with low alumina content, and the silica powder contains 0.5% by weight or more and 3% by weight or less of alumina and is ground to a Blaine specific surface area of 5000 to 10000 cn/9. is used.

Moreover, the mixing ratio of water and these raw materials is 5 to 15 in weight ratio of water/(slaked lime + silica powder).

Next, an example of a preferred method for producing the xonotlite molded article of the present invention will be described.

Alumina! so that S i 02 /CaO (molar ratio) is 1.00! U), 1 weight percent or less of slaked lime and alumina 10.5 weight percent or more of triple weight
Contains silica powder of less than cents, and adds 5 to 50% water to the raw materials.
Add 15 times the amount by weight and carry out a hydrothermal synthesis reaction to obtain a xonotrite slurry. Hydrothermal synthesis reactions are generally carried out using autoclaves. Based on 100 parts by weight of the solid content of the synthesized xonotrite slurry, 1 to 20 parts by weight of a polymer emulsion such as a styrene-butadiene copolymer or an acrylic ester polymer, and 1 to 10 parts by weight of reinforcement such as glass fiber, etc. After adding and mixing fibers, a dispersant, and an expansion material as necessary, this slurry is molded to have a bulk specific gravity of 0.3 to 0.7. As a molding method, for example, a method of filling a mold and dehydrating under pressure may be mentioned, but a conventionally known molding method may be appropriately adopted depending on the purpose and use. When this molded product is dried, the desired xonotlite-based molded product, so-called artificial wood, is obtained. The temperature for drying is not particularly limited, but a temperature of 100 to 180°C, usually 110 to 160'C is employed.

Examples of the present invention are shown below, but the present invention is not limited to the examples. In addition, in both cases, the pressure during pressure molding was set to 2 to 5.
Instead of different stages, molded bodies with different high specific gravity levels from 2 to 5 stages were prepared and their physical properties were tested.

[Example] The physical properties of the molded body were tested as follows.

(1) Bending strength: According to JIS A1408.

(2) Specific strength: (bending strength) / (bulk specific gravity -) (3)
Molding speed: Maximum molding speed at which slurry does not blow out of the mold during pressure molding.

(4) Drying shrinkage rate The thickness of the molded product after nibless molding and drying was measured to determine the shrinkage rate during drying.

Example 1 Silica stone powder 1 shown in Table 1 and slaked lime were mixed in 5 in2 :Ca
Blend so that the molar ratio of O is 1:1, add 12 times the amount of water to the raw material phase 1, and hydrothermally heat in an autoclave at a temperature of 210°C and a pressure of 19f (y/cri) for 3 hours with stirring. A synthetic reaction was carried out. Electron micrographs of the obtained xonotlite are shown in Figures 1 and 2. Table 2 shows the physical properties of the obtained xonotlite.

To the obtained xonotrite slurry, acrylic acid ester emulsion (manufactured by Showa Kobunshi ■, trade name AT-20) solid weight 5 was added to 100 parts by weight of xonotrite crystals.
Parts by weight, dispersant (manufactured by Fujisawa Yakuhin ■, trade name Balik #1)
0.5 parts by weight and expansion material (N gas chemical ■, trade name C3A
After adding and mixing 5 parts by weight of #20), 7 parts by weight of glass fiber (Nitto Boseki ■, trade name C812GYD) was added and mixed.

The obtained highly dispersed xonotrite slurry was press-molded and dried at 140°C for 16 hours to obtain a xonotrite-based molded body. The test results of the molded bodies are shown in Table 3.

Table 3 Single item Book L: kgf/cn+” Book 2:
kgf/cm” Book 3: kgf/cm2-min
*4:% Example 2 Figure 3 shows an electron micrograph of xonotlite obtained in the same manner as in Example 1, except that silica powder 2 shown in Table 1 was used as the silica raw material. Further, the physical properties of the obtained xonotlite are shown in Table 2.

The test results of the molded body obtained in the same manner as in Example 1 were
Shown in the table.

Example 3 FIG. 4 shows an electron micrograph of xonotlite obtained in the same manner as in Example 1, except that silica powder 3 shown in Table 1 was used as the silica raw material. Further, the physical properties of the obtained xonotlite are shown in Table 2.

Table 3 shows the test results of the molded bodies obtained in the same manner as in Example 1.

2 Comparative Example 1 FIG. 5 shows an electron micrograph of xonotlite obtained in the same manner as in Example 1, except that silica powder 4 shown in Table 1 was used as the silica raw material. Further, the physical properties of the obtained xonotlite are shown in Table 2.

The test results of the molded body obtained in the same manner as in Example 1 were
Shown in the table.

Table 4 (1) Unit d: kgf/cm” Book 2: kgf
/cm” book 3: kgf/cm”, min book 4
: % Table 4 (2) Single unit Book 1: kgf/cm2 Book 2: kgf
/cm2 Book 3: kgfz'c+y+'', min Book 4: % Comparative Example 2 Electrons of xonotlite obtained in the same manner as in Example 1, except that silica powder 5 shown in Table 1 was used as the silica raw material. A micrograph is shown in Fig. 6. The physical properties of the obtained xonotlite are shown in Table 2.

The test results of the molded body obtained in the same manner as in Example 1 were
Shown in the table.

Comparative Example 3 FIG. 7 shows an electron micrograph of xonotlite obtained in the same manner as in Example 1, except that silica powder 6 shown in Table 1 was used as the silica raw material. Further, the physical properties of the obtained xonotlite are shown in Table 2.

The test results of the molded body obtained in the same manner as in Example 1 were
Shown in the table.

Comparative Example 4 FIG. 8 shows an electron micrograph of xonotlite obtained in the same manner as in Example 1, except that quicklime shown in Table 1 was used instead of slaked lime. Further, the physical properties of the obtained xonotlite are shown in Table 2. Table 4 shows the test results of the molded bodies obtained in the same manner as in Example 1.

[Effects of the Invention] The present invention provides zonotrite spherical particles having a bulk specific gravity of 0.3 to 0.8 and suitably used as a molding material for building materials or artificial wood, and a method for producing the same.

[Brief explanation of the drawing]

Figures 1 and 2 are electron micrographs (magnification: 1
000x and 5000x). FIG. 3 is an electron micrograph (1000x magnification) showing the crystal structure of the zonotrite spherical particles obtained in Example 2. FIG. 4 is an electron micrograph (1000x magnification) showing the crystal structure of the zonotrite spherical particles obtained in Example 3. FIG. 5 is an electron micrograph (1000x magnification) showing the crystal structure of the zonotrite spherical particles obtained in Comparative Example 1. FIG. 6 is an electron micrograph (1000x magnification) showing the crystal structure of the zonotrite spherical particles obtained in Comparative Example 2. FIG. 7 is an electron micrograph (100x magnification) showing the crystal structure of the zonotrite spherical particles obtained in Comparative Example 3. FIG. 8 is an electron micrograph (1000x magnification) showing the crystal structure of the zonotrite spherical particles obtained in Comparative Example 4. Patent Applicant: Ube Industries, Ltd. Figure 1, Figure 2z @ Figure 3, ``l-Figure (Figure 7, Figure 8)

Claims (2)

[Claims] (1) Zonotlite spherical particles having a double shell structure, the inner and outer shells of which are connected in a network shape by needle-shaped xonotrite crystals. (2) Slaked lime with an aluminum oxide content of 0.1% by weight or less and silica powder with an aluminum oxide content of 0.5% by weight or more and 3% by weight or less are subjected to a hydrothermal synthesis reaction while stirring in the presence of water. A method for producing zonotolite spherical particles having a double shell structure, the inner shell and the outer shell of which are connected in a network shape by needle-like xonotrite crystals.