JPH0258227B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a water-repellent calcium silicate molded body, and an object thereof is to provide a calcium silicate molded body that has excellent water repellency even against hot water and steam, even inside the body. Calcium silicate molded bodies are inorganic, heat resistant, and porous, so they are used in many applications including fireproofing and heat insulating materials. However, since the molded body is porous, it has the disadvantage that it easily absorbs water, and when it absorbs water, its heat insulating properties decrease and its original purpose of use is lost. The inventors of the present invention have focused on the above-mentioned difficulties and have been conducting intensive research to solve them. It was discovered that a calcium silicate molded body having water repellency even inside the molded body could be produced by using the method, and an invention based on this knowledge was already filed (Japanese Patent Application No. 1983-
No. 99133 (Japanese Patent Application Laid-open No. 58-2252). As a result of further research, we found that molding and drying a slurry containing calcium silicate, fibrous substances, and silicone oil in the presence of aluminum sulfate can be carried out over a wide range of conditions without any particular limitations on manufacturing conditions. Therefore, it is possible to produce the desired molded product with an extremely industrial advantage, and the molded product thus obtained has a much improved water repellency compared to a molded product obtained by immediately adding silicone oil. He subsequently filed an application for an invention based on this knowledge (Japanese Patent Application No. 57-202361 and Japanese Patent Application Laid-Open No. 59-92963). Although the molded product obtained by the above production method has excellent water repellency, it still has the disadvantage that the water repellency against hot water of 60° C. or higher and water vapor is still insufficient. The inventor of the present invention focused on the above-mentioned difficulties and conducted further research. As a result, the inventors added aluminum sulfate and a mixture of methylhydrodiene polysiloxane and other silicone oil to an aqueous slurry consisting of calcium silicate and fibrous material. When drying with or without steam curing after forming,
It was discovered that a molded article with excellent water repellency against hot water and water vapor of 60° C. or higher can be obtained, and the present invention was finally completed. That is, the present invention involves adding methylhydrodiene polysiloxane and other silicone oil to an aqueous slurry of calcium silicate containing a fibrous material and aluminum sulfate, and drying the slurry with or without steam curing after molding. The present invention relates to a method for producing a calcium silicate molded body having water repellency. The aqueous slurry of calcium silicate used in the present invention includes a slurry of calcium silicate gel or quasi-crystals and a slurry of calcium silicate crystals. In order to produce the former calcium silicate gel or quasicrystal, a raw material slurry prepared from a silicate raw material, a lime raw material, and water may be heated and reacted. In preparing the latter calcium silicate crystal slurry, the above raw material slurry is heated under pressure while stirring to obtain a slurry of calcium silicate crystals all at once. All of these calcium silicate slurries are known, and include those produced by various manufacturing methods. These slurries contain fibrous substances.
As the aqueous slurry made of secondary particles of calcium silicate crystals containing or not containing fibrous substances, any of various known aqueous slurries can be used. Examples include those described in Japanese Patent Publication No. 55-29952. Calcium silicate crystals include various crystals belonging to the tobermolite group and the wollastonite group. In addition, any conventionally known aqueous slurry of calcium silicate gel or quasi-crystals containing or not containing fibrous substances can be used. You can. As the fibrous material, one or more types of organic fibers and inorganic fibers are used, and the former includes pulp, cotton, hemp, wool, wood fiber, rayon, polypropylene, polyacrylonitrile, polyamide, polyester, etc. Examples include asbestos, rock wool, glass fiber, ceramic fiber, carbon fiber, and metal fiber. The amount of the fibrous material added can be changed as appropriate depending on the intended use of the molded article, but it is usually about 1 to 30 parts by weight based on 100 parts by weight of the solid content in the crystal slurry. Methylhydrodiene polysiloxane has the general formula (However, n is 20 to 40.) It is a silicone oil represented by: Other silicone oils include dimethylpolysiloxane and some of its methyl groups as lower alkyl groups,
Those substituted with phenyl groups, amino groups, hydroxyl groups, etc. are used, and dimethylpolysiloxane having OH groups at both ends is preferably used. Methyl hydrodiene polysiloxane and other silicone oils are typically used in a mixed ratio of 8:2 to 2:8 by weight. By mixing and using silicone oil as described above, a molded article with excellent water repellency against hot water of 60° C. or higher and water vapor can be obtained. If the above ratio is exceeded, there is a tendency that the intended purpose will not be achieved. The total amount of both silicone oils added is 100% of the total amount of calcium silicate and fibrous material.
The amount is 1.5 to 7 parts by weight, preferably 2 to 5 parts by weight. If the amount added is extremely lower than 1.5 parts by weight, it is difficult to expect sufficient water repellency, and conversely, if the amount added is extremely lower than 7 parts by weight, the water repellent effect will hardly improve any further, and it will be uneconomical. Otherwise, the heat resistance tends to decrease. By adding aluminum sulfate, the production conditions are not particularly limited and can be carried out over a wide range of conditions, making it possible to produce the desired molded product with great industrial advantage, and also improving the water repellency of the resulting molded product. It is something. The amount of aluminum sulfate added is 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, on an anhydride basis, per 100 parts by weight of the total amount of calcium silicate and fibrous material. In this case, if the amount added is less than 0.5 parts by weight, a sufficient effect will not be obtained, and if it is added in excess of 10 parts by weight, no improvement in the effect can be expected, and the bending strength of the molded product will decrease. This is not desirable because it shows a tendency. In the present invention, the aqueous slurry thus prepared is molded and dried with or without steam curing, but prior to molding, various additives used in the production of this type of calcium silicate molded body are required. Added accordingly. Examples of additives in this case include cements, clays, water glass, and mica. Any of various conventional means can be used as the molding means, such as pressure dehydration molding, etc., and the drying means may be any conventional means, such as heating, natural drying, etc. . If the aqueous slurry of calcium silicate is a calcium silicate gel or quasi-crystal, it is steam-cured after molding. Steam curing may be carried out by a conventionally known method, and usually the calcium silicate gel or quasicrystal is crystallized and hardened under saturated steam pressure. Examples of calcium silicate quasicrystals include CSH and CSH. In the present invention, secondary particles of calcium silicate,
By adding a mixture of methylhydrodiene polysiloxane and other silicone oil and aluminum sulfate to an aqueous slurry containing a fibrous material, the slurry is stable under a wide range of conditions without being restricted by any manufacturing conditions. It has the advantage that a water-repellent molded body can be constantly produced, which is extremely advantageous industrially, and the obtained target molded body has excellent water repellency to the inside of the molded body. It has excellent water repellency without using a large amount of silicone oil, especially
This exhibits an extremely large effect in that a molded article having excellent water repellency against 60°C hot water and water vapor can be obtained. In addition, various excellent physical properties inherent to the calcium silicate molded body, such as bending strength, heat resistance, and heat insulation properties, hardly deteriorate. Examples of the present invention will be shown below. However, the method for measuring each physical property is as follows. Density (g/cm ³ ): JIS-A-9510 Bending strength (Kg/cm ² ): Same as above Water absorption rate (%): The molded product immediately after drying was cut in a cross section including the center part in the thickness direction. The sample was immersed 40 mm below the water surface, and the amount of water absorbed after 24 hours was measured to calculate the water absorption rate. However, the water absorption rate was determined by the following formula. Water absorption rate (%) = W - W ₀ / W ₀ × 100 where W is the weight of the molded product after 24-hour immersion, and
W ₀ indicates the weight of the molded body before immersion. (Unit: g) In the examples, parts and % indicate parts by weight and % by weight, respectively. Example 1 Silica stone powder was added to lime milk obtained by slaked quicklime in hot water and stirred at high speed, and then water was added to give a molar ratio (CaO/SiO ₂ )=1 and a water to solid content ratio (W /
S) = 24 to obtain a raw material slurry,
This was subjected to a hydrothermal synthesis reaction for 8 hours with stirring in an autoclave under saturated steam pressure at a pressure of 12 Kg/cm ² and a temperature of 191°C.
A crystal slurry in which approximately spherical secondary particles of 10 to 80 μm were dispersed in water was obtained. Crystal slurry obtained by the above method (solid content
100 parts of aluminum sulfate [Al ₂ (SO ₄ ) ₃・18H ₂ O〕
(Sumitomo Aluminum Smelting and Refining iron-free sulfate band, type: solid special number) on an anhydride basis, and methylhydrodiene polysiloxane (viscosity 30cp) as silicone oil and dimethylpolysiloxane with OT groups at both ends (viscosity 90cp). ) 1:1 (weight ratio)
Mixture [manufactured by Toray Silicone Co., Ltd., BY-16-805]
After adding and mixing 2.5 parts of the mixture shown in Table 1, the mixture was dehydrated under pressure and dried at 130°C to obtain a molded body. These molded bodies were immersed in hot water at the temperatures shown in Table 1, and their water absorption rates were measured. The obtained results are the first
Shown in the table.

[Table] Comparative Example 1 Aqueous slurry obtained by adding and mixing 7 parts of glass fiber and 5 parts of pulp as an aqueous suspension to the crystal slurry (solid content: 100 parts) obtained in the same manner as in Example 1. , the solids content of the aqueous slurry
To 100 parts, add 1.5 parts of the same aluminum sulfate as in Example 1 on an anhydride basis, and dimethylpolysiloxane [Toray Silicone Co., Ltd., SH200 oil].
500cs) was added and mixed in the amount shown in Table 2, followed by dehydration molding under pressure and drying at 130°C to obtain a molded product. These molded bodies were immersed in 70°C warm water, and their water absorption rates were measured. The results obtained are shown in Table 2.

[Table] Comparative Example 2 Methylhydrodiene polysiloxane (Toray Silicone Co., Ltd., SH1107) as silicone oil
A molded article was obtained in the same manner as in Comparative Example 1 except that . The obtained molded body was immersed in hot water at 70°C, and the water absorption rate was measured. The results obtained are shown in Table 3.

[Table] Example 2 Among the molded bodies obtained in the same manner as in Example 1, a molded body containing 2.5% silicone oil was heated to 75×
Cut to 200 x 200 mm, use this as a test specimen, and heat at 80℃.
A 200 mm portion of one side of the compact was brought into contact with saturated steam for 24 hours, and the water content was measured using the following formula, with the increase in weight of the compact as the amount of water absorbed. Moisture content (%) = Water absorption (g) / Test weight before contact with water vapor (g) x
100 The results obtained are shown in Table 4. The state of the water repellent layer refers to the condition of the water repellent layer, which means that after the test, room temperature water (20
~25℃), and if water is absorbed, the water repellent layer disappears.
If no water was absorbed, no change was considered.

[Table] Comparative Example 3 Among the molded bodies obtained in the same manner as in Comparative Example 1, the water content was measured in the same manner as in Example 2 using a molded body to which 2.5% silicone oil was added, and the state of the water-repellent layer was determined. Examined. The results obtained are shown in Table 5.

[Table] Example 3 Silica stone powder was added to lime milk obtained by slaking quicklime in hot water, and water was further added to give a molar ratio (CaO/SiO ₂ )=1 and a water to solid content ratio (W /S)=30
A raw material slurry was obtained by mixing to obtain a raw material slurry, which was subjected to a hydrothermal synthesis reaction for 2.5 hours with stirring in an autoclave under saturated steam pressure at a pressure of 14 Kg/cm ² and a temperature of 197°C to obtain quasi-crystalline CSH(I). A quasicrystalline slurry consisting of Example 1 After adding and mixing 1.5 parts of aluminum sulfate similar to that on an anhydride basis and 2.5 parts of silicone oil similar to Example 1,
Pressure dehydration molding. Next, this was reacted for 7 hours in an autoclave at a pressure of 15 kg/cm ² and a temperature of 200°C, and then dried at 130°C to obtain a molded product. These molded bodies were immersed in hot water at the temperatures shown in Table 6, and their water absorption rates were measured. The obtained results are shown in the sixth
Shown in the table.

【table】

Claims (1)

[Claims] 1. An aqueous slurry of calcium silicate containing a fibrous material and aluminum sulfate contains methylhydrodiene polysiloxane and other silicone oils, and after molding, the slurry is formed with or without steam curing. A method for producing a water-repellent calcium silicate molded product characterized by drying. 2. The manufacturing method according to claim 1, wherein the calcium silicate is a calcium silicate crystal.