JPS6317788B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a calcium silicate molded body and a method for producing the same, and more particularly to a zonotrite-based calcium silicate molded body containing amorphous carbon and a method for manufacturing the same. As a carbon-containing calcium silicate molded body, Tokkosho
No. 51-6038 describes a method for producing an activated carbon-containing calcium silicate molded body. In this manufacturing method, activated carbon is added to a slurry prepared from silicic acid raw materials, lime raw materials, and water in a specific amount of 0.5 to 7% by weight based on the solid content of the raw materials, and a hydrothermal synthesis reaction is carried out under stirring to form zonotrite crystals and activated carbon. This is formed into an aqueous slurry containing the above, and this is formed and dried. By adding a specific amount of activated carbon, the reaction rate of the above synthesis reaction can be increased and the amount of water can be significantly reduced. . It is also described that it has almost the same physical properties as the obtained carbon-containing zonotrite-based calcium silicate molded body. That is, although conventional activated carbon-containing calcium silicate molded bodies have some effects in terms of their manufacturing process, it has been thought that the molded bodies themselves have almost no specific effects. The present inventors have been conducting research on calcium silicate molded bodies for many years, and have discovered the following in this research. That is, in the activated carbon-containing raw material slurry, the content of amorphous carbon (including activated carbon) in the raw material slurry is 15% by weight or more.
When the amount is less than % by weight, the resulting molded product has a significantly high moisture absorption capacity. In particular, this hygroscopic ability has a close relationship with the amount of amorphous carbon, and it critically improves when the amount of amorphous carbon reaches 7% by weight, and in particular, the hygroscopic ability improves markedly when the amount of amorphous carbon exceeds 15% by weight. I found it. In addition, even though the amorphous carbon content is 15% by weight or more and 50% by weight or less, it is possible to obtain a molded product that is extremely lightweight and has sufficient practical strength, and the heat insulation performance is significantly improved. I found it. The present invention has been completed based on such knowledge. Namely, the present invention provides a molded article containing secondary particles of zonotrite crystals and amorphous carbon as main components, The particles exist in a compressed and deformed state and are interconnected, and the amorphous carbon is contained in the molded body in an amount of 15% by weight or more and 50% by weight or less, and as determined by differential thermal analysis.
An amorphous carbon-containing zonotrite-based calcium silicate molded body characterized by having an exothermic peak between 480°C and 600°C, and a substance whose main components are a silicic acid raw material, a lime raw material, and an amorphous carbon; A raw material slurry prepared such that the amount of water is 5 times or more by weight relative to the solid content, and the solid content contains 15% by weight or more and 50% by weight or less of a substance whose main component is amorphous carbon. An amorphous carbon-containing zonotrite system characterized by carrying out a hydrothermal synthesis reaction under pressure with heating and stirring to form an aqueous slurry mainly composed of zonotrite crystals and amorphous carbon, which is then molded and dried. The present invention relates to a method for producing a calcium silicate molded body. The amorphous carbon-containing calcium silicate molded article of the present invention contains amorphous carbon in an amount of 15% by weight or more and 50% by weight or less, and it is particularly noteworthy that if the amorphous carbon content in the molded article exceeds 7% by weight, The hygroscopicity of the molded body itself increases rapidly, and by containing 15% by weight or more, the hygroscopicity of the molded body itself is significantly improved. The present invention will be explained below based on its manufacturing method. In principle, the molded article of the present invention is produced by subjecting a raw material slurry prepared from a silicic acid raw material, a lime raw material, a substance mainly composed of amorphous carbon, and water to a hydrothermal synthesis reaction under stirring to form zonotrite crystals and amorphous carbon. It is manufactured by obtaining an aqueous slurry as the main component, molding it, and drying it. Activated carbon is a typical example of the substance containing amorphous carbon as a main component used in the present invention, and particles with a particle size of 150 μm or less, preferably 100 μm or less are usually used, but coarse particles may be partially mixed in. In addition, as the silicic acid raw material, any of those conventionally used in this type of calcium silicate molded body manufacturing method can be effectively used, such as silica stone, silica sand, etc. as the crystalline silicic acid raw material, and silica gel, silica flour, etc. as the amorphous silicic acid raw material. , white carbon, diatomaceous earth, etc. As raw materials for lime, any of the conventionally used materials can be used, such as quicklime, slaked lime,
Carbide slag or the like can be used as a specific example, and especially when producing a lightweight molded product, for example, a molded product with a density of about 0.1 g/cm ³ , it is preferable to use milk of lime with a settling volume of 5 ml or more. The sedimentation volume of the milk of lime refers to the sedimentation volume of lime particles after 50 ml of milk of lime with a water to lime solids ratio of 120 times is left to stand for 20 minutes in a measuring cylinder with a diameter of 1.3 cm and a volume of 50 cm ^or more. The sedimented volume is shown in ml. The amount of water is at least 5 times (weight) the solid content of the raw material slurry, and when producing the above lightweight body,
It is preferable to make it 15 times or more. The CaO/SiO ₂ molar ratio of the silicic acid raw material and the lime raw material is about 0.90 to 1.15. Inactive additives may be added to this raw material slurry in the subsequent hydrothermal synthesis reaction, and inorganic fibers such as asbestos, rock wool, etc. can be exemplified as additives at this time. The raw material slurry thus prepared is then subjected to a hydrothermal synthesis reaction while being stirred. This reaction condition is usually carried out under a saturated steam pressure of 8 Kg/cm ² or more, preferably 10 Kg/cm ² or more. As a result of this reaction, silicic acid and lime react, and secondary particles of approximately 5 to 100 μm in size, which are mainly composed of zonotrite crystals, are produced, and at the same time, a substance mainly composed of amorphous carbon coexisting in the raw material slurry is produced. A slurry is obtained in which these substances are uniformly dispersed in water. When this aqueous slurry mainly composed of zonotrite crystals and amorphous carbon is passed through a cloth, the liquid becomes transparent. The liquid will then turn black. Based on this fact, in the present invention, the substance mainly composed of amorphous carbon is contained in the secondary particles of the zonotrite crystal, or is attached to the particles by some force. considered to be a thing. Various additives may be added to the aqueous slurry containing the zonotrite crystals and amorphous carbon as necessary. As additives in this case, a wide range of materials can be used that have been used in the production of this type of calcium silicate molded body, such as fibers, clays, cements, etc., and more specifically, asbestos, rock wool,
Specific examples include inorganic fibers such as glass fibers and carbon fibers, organic fibers such as pulp, cellulose, and various synthetic fibers, clays such as kaolin and bentonite, gypsum, Portland cement, alumina cement, and other various cements. In the present invention, an amorphous carbon-containing zonotrite crystal molded body can be obtained by molding and drying the aqueous slurry by a conventional method. The molded product of the present invention obtained in this manner is mainly composed of secondary particles of zonotrite crystals and amorphous carbon, and the content of amorphous carbon in the molded product is approximately 15.0% by weight or more and 50% by weight or less. be.
This molded article has sufficient practical bending strength even though it is lightweight. What is particularly noteworthy is that the molded article has an extremely excellent moisture absorption ability. Hygroscopic ability has a close relationship with the amount of amorphous carbon contained, and according to the research of the present inventors, as shown in Table 5 and Figure 3 below, the content of amorphous carbon but
If the amount does not reach 15.0% by weight, the hygroscopicity does not increase significantly, but if it exceeds 15.0% by weight, the hygroscopicity rapidly increases significantly. In addition, the molded product of the present invention has a specific surface area of powder obtained by crushing it from 90 to 400.
m ² /g (measured using the BET method) and 480°C in differential thermal analysis (heating rate 10°C/min).
An exothermic peak is seen between 600℃ and 600℃. The molded article of the present invention is composed of secondary particles of calcium silicate crystals mainly composed of zonotrite crystals, amorphous carbon, or these and other additives, and the secondary particles are mutually compressed and deformed. It is configured by connecting. Moreover, among the molded bodies, high-density products are preferentially oriented. The method of the present invention will be specifically explained below with reference to Examples. However, various physical properties in the following examples were measured by the following methods. (a) Bending strength According to the method of JIS A 9510. (b) Preferred orientation degree (P) P=I(320)・I′(001)/I(001)・I′(3
20) However, I(320) and I(001) are the diffraction intensities of the non-oriented powder sample, and I'(320) and I'(001) are the diffraction intensities of the sample whose preferential orientation degree is to be measured. (c) Carbon content According to the method of JIS R 6124. (d) Specific surface area The compact is crushed and measured using the BET method. (E) Differential thermal analysis and thermogravimetric analysis Using a sample of approximately 10 mg obtained by crushing the compact,
Measurement is performed at a heating rate of 10°C/min. (F) Moisture absorption amount (at relative humidity of 90%) Relative humidity 90 adjusted using the method of JIS Z 0701
% decicator, and find the equilibrium moisture absorption amount (%) in the same atmosphere using the following formula. Moisture absorption amount (%) = W ₁ -Wo/Wo x 100 Wo: Dry weight of sample (g) W ₁ : Weight of sample that absorbed moisture (g) However, in the examples below, parts or % are not particularly explained. Parts or percentages by weight are given. Example 1 32.9 parts of quicklime (CaO95.0%) was added to 80°C warm water 394
The sedimentation volume of the milk of lime obtained by slaking in the chamber was 4.8 ml. A slurry obtained by dispersing 37.2 parts of ferrosilicon dust (SiO ₂ 90.2%) with an average particle size of 0.24 μm in the above milk of lime with 10 parts by weight of water using a homomixer for 2 minutes and activated carbon (manufactured by Takeda Pharmaceutical Co., Ltd., trade name) Shirasagi A)
Add 17.5 parts and further add water so that the total amount of water becomes 24 times the weight of the solid content to obtain ^a raw material slurry.
A hydrothermal synthesis reaction was carried out for 5 hours by stirring in an autoclave at 102 rpm with a stirring blade rotating at a rotation speed of 102 rpm to obtain a slurry. The slurry obtained above was heated to 100℃.
After drying for 24 hours, X-ray diffraction analysis revealed a peak of zonotrite crystals. Also, when this slurry is dried on a slide glass and observed under an optical microscope, the outer diameter is 5 to 100 μm.
Spherical secondary particles and irregularly shaped particles were observed, and when the slurry was observed under an electron microscope, it was found that the secondary particles were integrated with the same irregularly shaped particles as above. This electron micrograph (7500x magnification)
is shown in Figure 1. Chemical analysis of the dried slurry revealed that it contained 18.7% carbon. From the above, it can be seen that the amorphous particles observed above are mainly composed of amorphous carbon. Next, 7 parts of glass fiber and 3 parts of Portland cement were added as additives to 90 parts (solid content) of the slurry obtained above, and the mixture was press-molded and dried at 100° C. for 24 hours to obtain a molded product. The properties of the obtained molded product were as shown in Table 1.

[Table] Furthermore, when the fracture surface of molded body sample No. 1 listed in Table 1 was observed with a scanning electron microscope, the outer diameter was 5 to 100 μm.
It was observed that a mixture mainly composed of spherical secondary particles and amorphous carbon having an irregular shape were interconnected to form a molded body. This scanning electron micrograph (600x magnification) is shown in Figure 2. Furthermore, the same material composition is molded into a cylindrical shape, and 100
The molded body obtained by drying at ℃ for 24 hours (density
As a result of measuring the thermal conductivity of 0.102g/cm ³ ) using the method according to JIS A 9510, the thermal conductivity was 0.0480Kcal/mh.
deg (average temperature 167°C). Example 2 Add 49.3 parts of quicklime (CaO95.0%) to 591 parts of warm water at 80°C.
The sedimentation volume of the milk of lime obtained by slaking in the chamber was 4.8 ml. Slurry obtained by dispersing 55.7 parts of ferrosilicon dust (SiO ₂ 90.2%) with an average particle size of 0.24 μm in the above milk of lime with 10 times the weight of water in a homomixer for 2 minutes and activated carbon (manufactured by Takeda Pharmaceutical Co., Ltd., trade name) Shirasagi C)
Add 70 parts and further add water so that the total amount of water becomes 12 times the weight of the solid content to obtain a raw material slurry, which is heated at a saturated steam pressure of 12 Kg/cm ² and a temperature of 191°C
The mixture was stirred in an autoclave with a stirring blade rotating at a rotational speed of 102 rpm, and a hydrothermal reaction was carried out for 5 hours to obtain a slurry. The slurry obtained above was dried at 100°C for 24 hours,
When analyzed by X-ray diffraction, a peak of zonotrite crystal was observed. Also, when this slurry is dried on a slide glass and observed under an optical microscope, the outer diameter is 5 to 100 μm.
Spherical secondary particles and irregularly shaped particles were observed, and when the slurry was observed under an electron microscope, it was found that the secondary particles were integrated with the same irregularly shaped particles as above. Chemical analysis of the dried slurry revealed that it contained 38.1% carbon. From the above, it can be seen that the amorphous particles observed above are mainly composed of amorphous carbon. Next, 7 parts of glass fiber and 3 parts of Portland cement were added as additives to 90 parts (solid content) of the slurry obtained above, which was then press-molded and dried at 100°C for 24 hours to obtain a molded body. The properties of the obtained molded body were as shown in Table 2.

【table】

[Table] Furthermore, when the fracture surface of molded body sample No. 1 listed in Table 2 was observed with a scanning electron microscope, the outer diameter was 5 to 100 μm.
It was observed that a mixture whose main components were spherical secondary particles of m and amorphous carbon exhibiting an irregular shape were interconnected to form a molded body. Example 3 35.8 parts of quicklime (CaO95.0%) was added to 430 ml of warm water at 80°C.
The sedimentation volume of the milk of lime obtained by slaked in a vacuum chamber and dispersed in water using a homomixer was 13.7 ml. Silica stone powder (SiO ₂ 97.7
%) and 17.5 parts of the same activated carbon as in Example 1 were added, and water was further added so that the total amount of water was 24 times the weight of the solid content to obtain a raw material slurry. A slurry was obtained by stirring in an autoclave at 12 Kg/cm ² and at a temperature of 191° C. with a stirring blade rotating at a rotational speed of 138 rpm for 5 hours. The slurry obtained above was dried at 100°C for 24 hours,
X-ray diffraction analysis revealed peaks of zonotrite crystals and a small amount of tobermolite crystals. Also, when this slurry was dried on a slide glass and observed under an optical microscope, the outer diameter was 5 to 80 μm.
Spherical secondary particles and irregularly shaped particles were observed, and when the slurry was observed under an electron microscope, it was found that the secondary particles were integrated with the same irregularly shaped particles as above. Chemical analysis of the dried slurry revealed that it contained 18.2% carbon. From the above, it can be seen that the amorphous particles observed above are mainly composed of amorphous carbon. Next, 7 parts of glass fiber and 3 parts of Portland cement were added as additives to 90 parts (solid content) of the slurry obtained above, which was then press-molded and dried at 100°C for 24 hours to obtain a molded body. The properties of the obtained molded body were as shown in Table 3.

[Table] Furthermore, when the fracture surfaces of molded body samples No. 1 and 2 listed in Table 3 were observed with a scanning electron microscope, the outer diameters were 5 to 5.
It was observed that a mixture consisting mainly of spherical secondary particles of 80 μm and amorphous carbon exhibiting an irregular shape was interconnected to form a molded body. Reference example 1 Add 29.7 parts of quicklime (CaO95.0%) to 357 parts of warm water at 80°C.
The sedimentation volume of the milk of lime, which was slaked in a vacuum chamber and dispersed in water using a homomixer, was 10.6 ml. Add ferrosilicon dust to the lime milk as in Example 1.
A slurry obtained by dispersing 33.3 parts with 10 times the weight of water in a homomixer for 2 minutes and 7.0 parts of the same activated carbon as in Example 1 were added, and further water was added to make the total water amount 30 times the weight of the solid content. Mix to obtain a raw material slurry, which is heated to a saturated water vapor pressure of 12 Kg/cm ² and a temperature of 191
A hydrothermal synthesis reaction was carried out for 5 hours by stirring in an autoclave at 102 rpm with a stirring blade rotating at a rotation speed of 102 rpm to obtain a slurry. The slurry obtained above was dried at 100°C for 24 hours,
When analyzed by X-ray diffraction, a peak of zonotrite crystal was observed. Also, when this slurry is dried on a slide glass and observed under an optical microscope, the outer diameter is 5 to 100 μm.
Spherical secondary particles and irregularly shaped particles were observed, and when the slurry was observed under an electron microscope, it was found that the secondary particles were integrated with the same irregularly shaped particles as above. Chemical analysis of the dried slurry revealed that it contained 9.1% carbon. From the above, it can be seen that the amorphous particles observed above are mainly composed of amorphous carbon. Next, 7 parts of glass fiber and 3 parts of Portland cement were added as additives to 90 parts (solid content) of the slurry obtained above, which was then press-molded and dried at 100°C for 24 hours to obtain a molded body. The properties of the obtained molded body were as shown in Table 4.

[Table] Furthermore, when the fracture surfaces of molded body samples No. 1 and 2 listed in Table 4 were observed with a scanning electron microscope, the outer diameters were 5 to 5.
It was observed that a mixture whose main components were spherical secondary particles of 100 μm and amorphous carbon exhibiting an irregular shape were interconnected to form a molded body. Example 4 Silica stone powder (SiO ₂ 98.2%, average particle diameter 4.8 μm) was added to lime milk obtained by slaked quicklime (CaO 95.0%) in 80°C hot water so that the CaO/SiO ₂ molar ratio was 1.00. The activated carbon used in Example 1 was added to the raw material slurry obtained by adding and blending the raw material so as to have a predetermined amount. Furthermore, water was added and mixed so that the total amount of water was 25 times the weight of the solid content, and these were mixed in an autoclave at a saturated steam pressure of 20 Kg/cm ² and a temperature of 214°C using a stirring blade at a rotation speed of 138 r.pm. The mixture was stirred while rotating and a hydrothermal synthesis reaction was carried out for 1 hour to obtain a slurry of calcium silicate crystals. When each of the crystal slurries obtained above was dried at 100° C. for 24 hours and subjected to X-ray diffraction analysis, a peak of zonotrite crystals was observed in all of them. Next, each slurry obtained above was press-molded and dried at 100°C for 24 hours to obtain molded bodies No. 1 to No. 9.
I got it. Note that No. 1 to No. 7 are shown for comparison. The properties of the obtained molded body were as shown in Table 5.

[Table] In addition, the results in Table 5 are shown in the graph of Figure 3. From Table 5 and Figure 3, it can be seen that the carbon content in the compact does not affect the moisture absorption capacity up to 7.0% by weight.
When it exceeds 7.0% by weight, there is a critical improvement, especially at 15.0%.
It is clear that the hygroscopicity is significantly improved when the amount is greater than % by weight.

[Brief explanation of the drawing]

FIG. 1 is a 7500x electron micrograph of the slurry obtained in Example 1, and FIG. 2 is a 600x scanning electron micrograph of compact sample No. 1 also obtained in Example 1. FIG. 3 is a graph showing the relationship between the carbon content and moisture absorption amount of each molded body obtained in Example 5.

Claims (1)

[Scope of Claims] 1. A molded article mainly composed of secondary particles of zonotrite crystals and amorphous carbon, wherein the secondary particles of zonotrite crystals exist in a compressed and deformed state and are interconnected. , and the amorphous carbon is contained in the molded article in an amount of 15% by weight or more and 50% by weight or less, and has an exothermic peak between 480°C and 600°C according to differential thermal analysis. Zonotrite calcium silicate molded body containing regular carbon. 2 From the silicic acid raw material, the lime raw material, the substance whose main component is amorphous carbon, and water, the amount of water relative to the solid content is 5.
The raw material slurry, which has been adjusted so that the weight is more than double and the solid content contains 15% by weight or more and 50% by weight or less, is hydrothermally heated under pressure with stirring. A method for producing an amorphous carbon-containing zonotrite-based calcium silicate molded body, which comprises performing a synthesis reaction to obtain an aqueous slurry containing zonotrite crystals and amorphous carbon as main components, and then molding and drying this slurry.