JPH0258226B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a calcium silicate molded article and a method for producing the same, and more particularly to a water-repellent calcium silicate molded article and a method for producing the same. Calcium silicate molded bodies are inorganic, heat resistant, and porous, so they are used in many applications including fireproofing and heat insulation. 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. Various countermeasures have been considered in the past to solve this problem, such as applying or adsorbing a water repellent to the surface of the calcium silicate molded body, and impregnating it with metal soap or paraffin-based substances. However, the former is only for the surface, and if the molded body is cut or drilled at the site of use, it is no longer possible to prevent water absorption unless the machined surface is retreated, and the latter is not sufficient. It is difficult to impart water repellency, and when the amount of impregnation is increased, the inherent heat insulating properties of the calcium silicate molded article are reduced, and in particular, the heat resistance is extremely impaired. In addition, conventional ALC (lightweight cellular concrete) has been made using silicone oil to make the molded body water repellent, but ALC has low heat resistance and has closed cells.
Water-repellent molded heat insulating materials are also made by molding expanded particles such as perlite with adhesive, but these also have voids made of closed cells. On the other hand, for materials with high porosity and continuous voids, such as lightweight calcium silicate moldings used in general heat insulating materials, it is extremely difficult to apply water repellent treatment to the inside of the molded material. It was difficult. The inventors of the present invention have focused on the above-mentioned difficulties and have been conducting intensive research in order to resolve them. It was discovered that a water-repellent calcium silicate molded body could be produced by molding and drying this, and an invention based on this knowledge was already filed (Japanese Patent Application No. 56-99133, JP-A No. 58-2252). . Although this method can produce calcium silicate molded bodies with excellent water repellency, there are restrictions on the manufacturing conditions, and it is necessary to select appropriate manufacturing conditions. There was another problem in industrial implementation as equipment, etc. was required. As a result of further research into the above invention, the present inventor found that when aluminum sulfate is further contained in a slurry containing secondary particles of calcium silicate crystals, a fibrous substance, and silicone oil, and the slurry is molded and dried, The conditions are not particularly limited and can be carried out over a wide range of conditions, and the desired molded product can be manufactured with extremely industrial advantage, and the molded product thus obtained can be easily obtained by simply adding silicone oil. In comparison, we discovered a new fact that the water repellency is further improved, and finally completed the present invention. That is, the present invention provides a molded article containing calcium silicate crystals, a substance produced by the reaction of the crystals with aluminum sulfate, a fibrous substance, and silicone oil, wherein the calcium silicate crystals form secondary particles. Silicone is added to an aqueous slurry containing a calcium silicate molded body in which the secondary particles are interconnected and the silicone oil is partially combined with calcium silicate crystals, and the secondary particles of the calcium silicate crystals and a fibrous material. The present invention relates to a method for producing a calcium silicate molded body, which is characterized in that oil and aluminum sulfate are added and mixed, then molded and dried. The molded article of the present invention is substantially composed of interconnected secondary particles of calcium silicate crystals,
This contains a substance produced by the reaction between calcium silicate crystals and aluminum sulfate (hereinafter simply referred to as aluminum sulfate reactant) and silicone oil partially bound to the crystals. In this way, since the aluminum sulfate reactant is further contained, the water repellency is further improved compared to a molded article containing only silicone oil in the above state.
Water repellency is exhibited by the silicone oil bonding with calcium silicate crystals, and this water repellency is further improved by the coexistence of the aluminum sulfate reactant. The fact that silicone oil is bound to calcium silicate crystals can be easily confirmed by the fact that silicone oil is not extracted when extracted with n-hexane. Silicone oil exhibits water repellency if it is contained in the molded article in an amount of at least 0.5% by weight, and it does not necessarily have to be contained uniformly throughout the molded article. For example, the content of silicone oil in the outer periphery of the molded body may be greater than that in the center (as long as the content is 0.5% by weight in the center). The silicone oil content of the entire molded product is the total amount of calcium silicate crystals and fibrous material.
Preferably about 0.5 to 7 parts by weight per 100 parts by weight
The amount is about 1.5 to 5 parts by weight, most preferably about 2 to 4 parts by weight. In this case, if the amount is extremely less than 0.5 parts by weight, it is difficult to expect sufficient water repellency, and conversely, if the amount is extremely less than 7 parts by weight, it is not only uneconomical but also tends to lower heat resistance and strength. There is. The products produced by the reaction between aluminum sulfate and aluminum silicate crystals refer to various substances produced as a result of adding and mixing aluminum sulfate to an aqueous slurry consisting of secondary particles of calcium silicate crystals, shaping and drying this. . Therefore, the types of substances produced differ slightly depending on the drying conditions, such as dihydrate gypsum and hemihydrate gypsum, but this point is secondary to the present invention, and the important point is that calcium silicate and calcium sulfate are produced. It suffices if it contains those produced as a result of the drying of the crystals. The amount of the substance produced in the reaction mainly depends on the amount of aluminum sulfate used, and it is sufficient that the amount produced substantially corresponds to 0.5 to 10 parts by weight of the aluminum sulfate added. When producing the molded article of the present invention, silicone oil and aluminum sulfate are added to an aqueous slurry in which secondary particles of calcium silicate crystals are dispersed in water with or without a fibrous material, along with a fibrous material as necessary. Obtained by mixing, shaping and drying. The aqueous slurry itself consisting of secondary particles of calcium silicate crystals, which may or may not contain fibrous substances, used in this case has been known for a long time, and in the present invention, any of the various known aqueous slurries may be used. Can be used, for example, Special Publication No. 45-25771, Special Publication No. 43494, Special Publication No. 52-43494, Special Publication No. 55-
Examples include those described in Publication No. 29952 and the like. Calcium silicate crystals include various crystals belonging to the tobermolite group and the wollastonite group. As the fibrous material, one or more types of organic fibers and inorganic fibers are used, and the former includes pulp, cotton, linen, wool, wood fiber, rayon, polypropylene, polyacrylonitrile, polyamide, polyester, etc. are asbestos, rock wool, glass fiber, ceramic fiber,
Examples include carbon fiber and metal fiber. The amount of the fibrous material added can be changed depending on the purpose of use of the molded article of the present invention, but it is usually added in an amount of 1 to 30 parts by weight per 100 parts by weight of the solid content in the crystal slurry. As the silicone oil used, dimethylpolysiloxane and its methyl groups are partially substituted with hydrogen atoms, lower alkyl groups, phenyl groups, amino groups, hydroxyl groups, etc. are used. The amount added is the total amount of calcium silicate crystals and fibrous substances.
1.5 to 7 parts by weight, preferably 2 to 5 parts by weight per 100 parts by weight
Parts by weight. In the present invention, aluminum sulfate is used in an amount of 0.5 to 10 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the total amount of calcium silicate crystals and fibrous material.
It is 5 parts by weight. 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, but prior to molding, various additives used in the production of this type of calcium silicate molded body are added as necessary. 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, and the drying means can be any conventional means, such as heating, leaving to stand, etc. Ru. In the present invention, by adopting a method of adding aluminum sulfate to a slurry of secondary particles of calcium silicate crystals, a molded article having stable water repellency under a wide range of conditions without being restricted by any manufacturing conditions can be obtained. It has the advantage that it can be produced constantly, which is very industrially advantageous, and the obtained molded object has extremely excellent water repellency, without using a particularly large amount of silicone oil. For example, even if the amount of silicone oil used is 4% by weight or less, it is possible to obtain a molded article having extremely excellent water repellency. It also has the effect of forming a molded product with uniform water repellency. In addition, the various excellent physical properties inherent to the calcium silicate molded body, such as heat resistance and heat insulation properties, hardly deteriorate. EXAMPLES The present invention will be specifically described below with reference to Examples. However, the physical properties in the following examples were measured by the following methods. In addition, parts indicate parts by weight. Density (g/cm ³ ): JIS-A-9510 Bending strength (Kg//cm ³ ): Same as above Water absorption: The obtained molded body was cut in a cross section including the center of the thickness, and the water head was 40mm below. The water absorption rate was calculated by measuring the amount of water absorbed after soaking in water for 24 hours. 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) The amount of silicone in the molded product was determined by crushing the molded product, thermally decomposing it with ethyl silicate [Si(OC ₂ H ₅ ) ₄ ] and KOH, and analyzing it by gas chromatography using ethyl alcohol as a solvent. Example 1 A raw material slurry was prepared by suspending 26.9 parts of ferrosilicon dust, 26.9 parts of silica powder, and 46.2 parts of quicklime (CaO/SiO ₂ molar ratio = 1) in water such that the water-to-solids ratio was 24. This was subjected to a hydrothermal reaction for 8 hours while stirring in an autoclave at a pressure of 12 kg/cm ² and a temperature of 191°, resulting in crystals of zonotrite crystals with diameters of 5 to 50 mm.
A crystalline aqueous slurry of approximately spherical secondary particles of 50 μm was obtained. To 100 parts (solid content) of the crystal slurry obtained above, 7 parts of glass fiber and 2 parts of pulp were added and mixed as an aqueous suspension, and then dimethylpolysiloxane (manufactured by Toray Silicone Co., Ltd.) was added to 100 parts of the solid content. ,
"SH200 oil" 500 cs), 3 parts, and aluminum sulfate [Al(SO ₄ ) _{3.18H 2} O] (Sumitomo Aluminum Works, iron-free sulfate band, solid special issue) are shown in Table 1 on an anhydride basis. A predetermined amount was added and mixed well. Next, it was subjected to pressure dehydration molding and dried at 130°C for 13 hours to obtain a molded product. The physical properties of these molded bodies are shown in Table 1 below. Further, the obtained molded body was crushed and immersed in n-hexane, but no silicone oil was extracted.

[Table] Also, take 2g of powder obtained by crushing the molded body obtained above, mix it with 20ml of ethanol, hydrochloric acid (1+
1) Add 20ml and 60ml of distilled water and elute in a water bath at 70-80℃ for 30 minutes.
Table 2 shows the results of quantification of sulfate ions using the gravimetric method of JIS-K-0101 42.3.

[Table] Example 2 Aqueous slurry obtained by adding and mixing 7 parts of glass fiber and 2 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, 1.5 parts of the same aluminum sulfate as in Example 1 on an anhydride basis and the same amount of silicone oil as in Example 1 as shown in Table 3 were added and mixed, followed by pressure dehydration molding at 130°C. A molded article was obtained by drying for 13 hours. The results of measuring the physical properties of these molded bodies are also shown in Table 3.

[Table] Furthermore, although the molded product of the above example was crushed and n-hexane was added, silicone was not extracted. Furthermore, molded bodies No. 4 to 9 were prepared at room temperature (25 to 30℃).
The results of measuring the water absorption rate after leaving it for 13 days are shown in the fourth column.
Shown in the table.

[Table] Example 3 Aqueous slurry obtained by adding and mixing 7 parts of glass fiber and 2 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, 1.5 parts of the same aluminum sulfate as in Example 1 on an anhydride basis and dimethylpolysiloxane (manufactured by Toray Silicone Co., Ltd., SH200 oil) with various viscosities (at 25°C) shown in Table 5 were added. 3 things
After addition and mixing, pressurized and dehydrated molding was carried out at 130℃ for 13 minutes.
A molded article was obtained by drying for a period of time. Also, instead of the silicone oil mentioned above, 2 methyl groups of dimethylpolysiloxane 630cs are added in one molecule.
A molded article was obtained in the same manner as above except that a silicone oil substituted with ~3 H groups and a silicone oil in which a trace amount of the methyl group of dimethylpolysiloxane 380cs was substituted with an amino group were used. The results of measuring the physical properties of these molded bodies are also shown in Table 5.

[Table] Furthermore, although the above molded body was crushed and n-hexane was added, silicone was not extracted. Example 4 52 parts of silica powder and milk of lime with a settling volume of 46 ml were mixed with CaO
45.6 parts (CaO/SuO ₂ molar ratio = 1) were mixed so that the water to solid content ratio was 24 times, and the mixture was heated under pressure.
The reaction was carried out at 12 kg/cm ² and a temperature of 191° C. for 8 hours with stirring in an autoclave to obtain an aqueous slurry of approximately spherical secondary particles of zonotrite crystals with a diameter of 10 to 80 μm. 100 parts of the crystal slurry obtained above (solid content)
To the aqueous slurry obtained by adding and mixing 7 parts of glass fiber and 2 parts of pulp, the same aluminum sulfate as in Example 1 was added to the solid content of the aqueous slurry (100 parts) as shown in Table 6 on an anhydride basis. Two parts of silicone oil in the same amount as in Example 1 were added and mixed, followed by pressure dehydration molding and drying at 130° C. for 13 hours to obtain a molded product. Table 6 also shows the results of measuring the physical properties of the obtained molded product. Although the molded body was crushed and immersed in n-hexane, no silicone oil was extracted.

[Table] No. 1 shows a comparative example.
Example 5 A raw material slurry was prepared by mixing 52.6 parts of silica powder and 47.4 parts of quicklime (CaO/SiO ₂ molar ratio = 0.975) with water such that the water to solid content ratio was 12 times. The slurry was reacted for 8 hours with stirring in an autoclave at a pressure of 12 Kg/cm ² and a temperature of 191° C. to obtain an aqueous slurry consisting of approximately spherical secondary particles with a diameter of 10 to 150 μm and mainly composed of zonotrite crystals. 5 parts of glass fiber and 3 parts of pulp are added and mixed as an aqueous suspension to the crystal slurry obtained by the above method (solid content 100 parts), and the solid content of the aqueous slurry is mixed. For every 100 parts, 5 parts of Portland cement, bentonite
10 parts of aluminum sulfate as in Example 1 were added as an aqueous suspension in the amounts shown in Table 7 on an anhydrous basis;
Then, 45 parts of the same silicone oil as in Example 1 was added and mixed, followed by pressure dehydration molding and drying at 130° C. for 13 hours to obtain a molded product. The results of measuring the physical properties of these molded bodies are also shown in Table 7.

[Table] Furthermore, although the molded bodies of Examples were crushed and n-hexane was added, silicone was not extracted. Furthermore, the results of quantitative analysis of aluminum and sulfate ions in the same manner as in Example 1 are presented in the eighth example.
Shown in the table.

[Table] Note that Comparative Examples indicate the analysis results of molded bodies to which no aluminum sulfate was added. Example 6 56.6 parts of silica powder and 43.4 parts of lime-free (CaO/CiO ₂
A raw material slurry was prepared by mixing the raw material slurry (mole ratio = 6.83) with water such that the water to solid content ratio was 12 times. This was reacted in an autoclave at a pressure of 8 kg/cm ² and a temperature of 175° C. for 5 hours to obtain a crystal slurry of approximately spherical secondary particles consisting of tobermolite crystals and having a diameter of 10 to 150 μm. Crystal slurry obtained above (solid content 100 parts)
To the aqueous slurry obtained by adding and mixing 5 parts of glass fiber and 3 parts of pulp as an aqueous suspension, 5 parts of Portland cement and 10 parts of bentonite were added in water per 100 parts of the solid content of the aqueous slurry. After adding as a suspension, 1.5 parts of aluminum sulfate similar to Example 1 on an anhydride basis and 4.5 parts of silicone oil similar to Example 1 were added and mixed, followed by pressure dehydration molding and drying at 130°C for 13 hours. A molded body was obtained. Table 9 shows the results of measuring the physical properties of the obtained molded product.

[Table] Furthermore, although the molded body was crushed and n-hexane was added, silicone was not extracted.

Claims (1)

[Scope of Claims] 1. A molded article containing calcium silicate crystals, a substance produced by the reaction of the crystals with aluminum sulfate, a fibrous substance, and silicone oil, wherein the calcium silicate crystals form secondary particles. A calcium silicate molded article, wherein the secondary particles are interconnected, and the silicone oil is partially contained in a state bonded to calcium silicate crystals. 2. Calcium silicate according to claim 1, which is obtained by molding and drying an aqueous slurry containing secondary particles of calcium silicate crystals, a fibrous substance, silicone oil, and a substance produced by the reaction of aluminum sulfate with the crystals. Molded object. 3. A method for producing a calcium silicate molded article, which comprises adding and mixing silicone oil and aluminum sulfate to an aqueous slurry containing secondary particles of calcium silicate crystals and a fibrous substance, followed by molding and drying. 4 The amount of the silicone oil and aluminum sulfate (anhydrous basis) added is 1.5 to 7 parts by weight and 0.5 to 7 parts by weight, respectively, based on 100 parts by weight of the total amount of calcium silicate crystals and fibrous material in the aqueous slurry.
10 parts by weight of the method according to claim 3.