JPH059390B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a calcium silicate molded article, and more particularly to a calcium silicate molded article having excellent water repellency. A calcium silicate molded body substantially composed of interconnected secondary particles of calcium silicate crystals is
Because it is inorganic, heat-resistant, and porous, it is used for many purposes, including fireproofing and 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 performance 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, or impregnating it with metal soap or paraffin-based substances. A method is known, but in the former method, only the surface is water repellent, and if the molded body is cut or drilled at the site of use, water absorption will be prevented unless the machined surface is treated again. In the latter case, it is difficult to impart sufficient water repellency, and when the content of the water repellent agent is increased, the original heat insulation properties of the calcium silicate molded product decrease, and furthermore, its heat resistance becomes extremely low. It has the disadvantage of being damaged. On the other hand, JP-A-57-123851 discloses a method of imparting water repellency to calcium silicate molded bodies by adding and mixing an emulsion obtained by emulsifying dimethylpolysiloxane and/or its derivatives with an anionic surfactant. The method of dehydration molding is described. However, in this method, dimethylpolysiloxane and/or its derivatives that exhibit water repellency flow out with water during the dehydration molding process during molded product production, or migrate to the surface of the molded product together with moisture.
There is a problem in that it is difficult to impart sufficient water repellency to the inside of the molded body, and the molded body as a whole cannot exhibit satisfactory water repellency. In order to solve this problem, if a large amount of silicone oil emulsion is blended to contain a sufficient amount of water repellency, the water repellent content on the outer periphery of the molded product will inevitably increase proportionately. However, the bending strength of the molded product is extremely reduced, and its practical value as a calcium silicate molded product is lost. In this way, for a calcium silicate molded body that is substantially composed of interconnected secondary particles of calcium silicate crystals and has a high porosity and the vacancies are continuous, the inside of the molded body is It was simply impossible to perform a water-repellent treatment to such an extent that even today, this type of calcium silicate molding maintains the necessary strength as a molded product and has excellent water repellency not only on the surface but also on the inside. The body has not yet been reported. The present invention solves the above-mentioned conventional problems, and provides a calcium silicate molded body that has excellent water repellency, has sufficient water repellency not only on the surface but also on the inside, and has strength as a molded body. It was done for the purpose of That is, the present invention provides a calcium silicate molded article substantially composed of interconnected secondary particles of calcium silicate crystals and containing a fibrous material and silicone oil, wherein the silicone oil - exists bonded to calcium silicate crystals from the outer periphery to the center of the molded product in a state that is not substantially extracted even when immersed in hexane, and the silicone oil content in the center of the molded product is at least 0.5% by weight %, and the ratio (weight) of the silicone oil content at the outer periphery of the molded body to the silicone oil content at the center of the molded body is 4 times or less. . The molded product of the present invention is made up of secondary particles of calcium silicate crystals that are compressed and deformed and connected to each other, and in addition to the conventional molded product that uniformly contains a fibrous material, silicone It is characterized in that oil is further contained in the formed body from the outer periphery to the center in a state of bonding with calcium silicate crystals. The bond between the silicone oil and the calcium silicate crystals is so strong that the silicone oil is not substantially extracted even if the molded article is immersed in n-hexane. According to the results of quantitative analysis of silicone in the molded body of the present invention, the content of silicone in the center of the molded body reaches at least 0.5% by weight. In addition, the ratio (weight) of the silicone oil content in the outer periphery of the molded body to the silicone oil content in the center of the molded body is usually 4 times or less,
In some cases, it is less than double. As described above, the molded article of the present invention exhibits excellent water repellency because the silicone oil combined with calcium silicate crystals is present from the outer periphery to the center of the molded article. In this case, the silicone oil concentration in the center of the molded body is 0.5% by weight or more, so
The center of the molded body also has excellent water repellency. Although the bond between silicone oil and calcium silicate crystals is not clear, it is due to the hydrogen bond (-OH ⁺ ...O ^- -) between the oxygen atom (O) of the silicone oil and the hydroxyl group (-OH) on the surface of the calcium silicate crystal. It is estimated that Furthermore, the reason why the entire molded product exhibits excellent water repellency due to the combination of silicone oil with calcium silicate crystals is still unclear despite the inventor's research, but it is probably due to the above-mentioned combination. This is because some change occurs in the coiled molecular structure of the silicone oil, and this change causes the hydrophobic groups of the coiled molecule to align to the outer surface of the calcium silicate crystal and become in a state where it covers the calcium silicate crystal. Guessed. In other words, the silicone oil easily adsorbed and retained by the secondary particles composed of fine crystals of calcium silicate does not flow out during pressurized dehydration molding due to such adsorption, and is substantially retained as is. Then, during drying, the retained silicone oil combines with the calcium silicate crystals, so that the calcium silicate crystals are covered with the hydrophobic groups of the silicone oil. In this way,
It is thought that since the individual calcium silicate crystals in the molded article are covered with the hydrophobic groups of the silicone oil, the entire molded article exhibits water repellency as a result. The feature of the molded product of the present invention is that a sufficient amount of silicone oil is present not only on the surface of the molded product but also in the center.
It exists in combination with calcium silicate crystals. As is clear from the examples below, the silicone oil content in the center of the molded product of the present invention is at least
The content is 0.5% by weight, preferably 1% by weight or more, more preferably 1.5% by weight or more, which imparts water repellency not only to the surface but also to the inside, and exhibits excellent water repellency as a whole. The ratio (weight) of the silicone oil content at the outer periphery of the molded body to the silicone oil content at the center of the molded body is:
As is clear from the examples below, even the largest
0.8/2.9 (Table 2 No. 1), usually less than 4 times,
In some cases, it is less than double. The silicone oil content with respect to the entire molded body is about 1 to 7% by weight, preferably about 2 to 4% by weight. At this time, if the silicone oil content becomes extremely high,
For example, if it reaches 10% by weight or more, it is not only disadvantageous in terms of cost, but also reduces heat resistance or strength. Furthermore, if the amount becomes extremely low, sufficient water repellency cannot be exhibited. Incidentally, the content of silicone oil can be easily determined, for example, by the following method. That is, a sample is obtained by crushing a compact,
In the presence of KOH, ethyl silicate [Si
(OC ₂ H ₅ ) ₄ ] to decompose it into silicone monomers, which can then be quantified by gas chromatography. In producing the molded article of the present invention, an aqueous slurry containing calcium silicate secondary particles, a fibrous substance, and silicone oil is molded and dried. When preparing an aqueous slurry containing the above three materials, silicone oil and, if necessary, a fibrous material are usually added and mixed to an aqueous slurry of secondary particles of calcium silicate crystals that may or may not contain a fibrous material. At this time, the aqueous slurry of secondary particles of calcium silicate crystals that may or may not contain a fibrous substance is well known, and in the present invention, a wide range of previously known slurries can be used. , for example, Special Publication No. 45-25771,
Examples include those described in Japanese Patent Publication No. 52-43494 and Japanese Patent Publication No. 55-29952. Further, calcium silicate crystals include tobermolite group crystals and wollastonite group crystals. As the fibrous material, one or more selected from organic fibers and inorganic fibers are used, and the former includes pulp, cotton, linen, wool, wood fiber, rayon, polypropylene, polyacrylonitrile, polyamide, and polyester. etc.,
Examples of the latter include asbestos, rock wool, glass fiber, ceramic fiber, carbon fiber, and metal fiber. The content of the fibrous substance is about 1 to 30% by weight based on 100% by weight of the solid content of the aqueous slurry of calcium silicate crystals. Examples of the silicone oil used in the present invention include dimethylpolysiloxane and those in which a portion of the methyl groups are substituted with hydrogen atoms, lower alkyl groups, phenyl groups, amino groups, hydroxyl groups, etc. In the present invention, a slurry containing these three components is molded and dried to obtain a desired molded product, but various additives may be added to the aqueous slurry prior to molding. As the above-mentioned additives, those used in the production of this type of calcium silicate molded body can be effectively used, and typical examples include cements, clay, and water glass. As the molding means, any of the various means used in this field can be used, such as a pressure dehydration molding method. Then, the obtained molded body is dried. Drying at this time is usually carried out by heating, but it may also be allowed to cool naturally. The molded product of the present invention varies depending on the density of the secondary particles of calcium silicate crystals used, the types and amounts of the fibrous substances and various additives added, but generally the pressure during molding is As the size of the secondary particles increases, in other words, as the density of the compact increases, the shape of the secondary particles becomes flattened in the compression direction. In the case of a compact having a small density, when the fractured surface of the compact of the present invention is observed under a scanning electron microscope, it is found that the secondary particles are interconnected to form the compact. As the density of the compact increases, the secondary particles become more flattened and it becomes difficult to directly and clearly detect the presence of the secondary particles using a scanning electron microscope. This fact indicates that calcium silicate crystals are preferentially oriented, and is confirmed by the fact that the diffraction intensity of the (00l) plane becomes abnormally high when X-rays are irradiated in a direction perpendicular to the pressing direction of the compact. be able to. The molded article of the present invention has excellent water repellency even within the body, and even if it is cut or drilled during use, it still exhibits excellent water repellency. Furthermore, despite the silicone oil content, the characteristics of calcium silicate molded bodies such as heat resistance and heat insulation are not impaired, and the mechanical strength is also excellent. EXAMPLES The present invention will be specifically explained below with reference to Examples. In addition, each physical property in the following example was measured by the following method, and parts indicate parts by weight. Density (g/cm ³ ); JIS-A-9510 Bending strength (Kgf/cm ² ); Same as above Water absorption rate (%); The obtained molded body was cut in a cross section including the center of the thickness, and the height was 40 mm below the water head. The water absorption rate was calculated by measuring the amount of water absorbed after 24 hours. still,
The water absorption rate was determined by the following formula. Water absorption rate (%) = (W-W ₀ )/W ₀ However, W is the weight of the molded body after 24-hour immersion,
W ₀ indicates the weight of the molded body before immersion. In addition, the amount of silicone in the molded product can be determined by crushing the molded product and converting it into ethyl silicate [Si(OC ₂ H ₅ ) ₄ ],
It was thermally decomposed with KOH and analyzed by gas chromatography using ethyl alcohol as a solvent. Note that the thickness of the molded bodies created in the present Examples and Comparative Examples was all 40 mm. 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 so that the water-to-solids ratio was 24. The pressure is 12Kg/cm ² and the temperature is
A hydrothermal reaction was carried out at 191° C. for 8 hours with stirring in an autoclave to obtain a crystalline aqueous slurry of approximately spherical secondary particles of zonotrite crystals with a diameter of 5 to 50 μm. To 100 parts (solid content) of the crystal slurry obtained above,
Add and mix 7 parts of glass fiber and 2 parts of pulp as an aqueous suspension, and then add dimethylpolysiloxane ("SH200 Oil" 500cs, manufactured by Toray Silicone Co., Ltd.) in the specified amount shown in Table 1 to 100 parts of the solid content. The mixture was carried out in the following manner. That is, at a temperature of 70° C., the mixture was stirred and mixed for 20 minutes at a rotation speed of 391 rpm using an inclined paddle blade having a shaft diameter of 95 mm and a blade width of 20 mm in a stainless steel container having a diameter of 140 mm and a depth of 200 mm. Then, it was dehydrated under pressure and molded at 130℃ for 13 hours.
A molded article was obtained by drying for a period of time. Table 1 shows the physical properties of these molded bodies. Further, the obtained molded body was crushed and immersed in n-hexane, but no silicone oil was extracted at all. Comparative Example 1 A 35% aqueous emulsion ("SM8706" manufactured by Toray Silicone Co., Ltd.) made by emulsifying dimethylpolysiloxane with an anionic surfactant was added to a slurry containing the same zonotrite crystals, glass fibers, and pulp as in Example 1. Dimethylpolysiloxane was added and mixed in a ratio of 4 parts to 100 parts of solid content. This was dehydrated and molded, and then dried at 130°C to obtain a molded body. The physical properties of the obtained molded product are shown in Table 1 (No. 6). Comparative Example 2 The same procedure as Comparative Example 1 was conducted except that the amount of dimethylpolysiloxane added was 10 parts. The physical properties of the obtained molded product are shown in Table 1 (No. 7).

[Table] Shows the results of 1 and 2.

Example 2 100 parts of crystal slurry obtained in Example 1 (solid content)
7 parts of glass fiber and 2 parts of pulp were added and mixed, and then 4 parts of dimethylpolysiloxane ("SH200 oil" manufactured by Toray Silicone Co., Ltd.) of each viscosity shown in Table 2 was added to 100 parts of the solid content. Mixed thoroughly. This was dehydrated and molded, and then dried at 130°C for 13 hours to obtain a molded body. In addition, the above dimethylpolysiloxane (viscosity
1 methyl group of 630cs dimethylpolysiloxane
(substituted with 2 to 3 hydrogen atoms in the molecule), and amino group-substituted dimethylpolysiloxane (with viscosity
A molded article was obtained using 380cs dimethylpolysiloxane (in which a very small amount of methyl group was replaced with an amino group), and the other treatments were carried out in the same manner. The physical properties of these molded bodies are shown in Table 2. Furthermore, although these molded bodies were crushed and immersed in n-hexane, no silicone oil was extracted. Furthermore, when the fractured surfaces of these molded bodies were observed with a scanning electron microscope, it was found that they were composed of approximately spherical secondary particles interconnected with each other.

[Table] Example 3 52.6 parts of silica powder and 47.4 parts of quicklime (CaO/
SiO ₂ molar ratio = 0.975) was suspended in water so that the water to solid content ratio was 12 to prepare a raw material slurry, and this was stirred in an autoclave at a pressure of 12 Kg/cm ² and a temperature of 191°C. A hydrothermal reaction was carried out for a period of time to obtain a crystalline aqueous slurry of approximately spherical secondary particles having a diameter of 10 to 150 μm and consisting of zonotrite crystals. To 100 parts (solid content) of the crystal slurry obtained above,
Add and mix 6 parts of glass fiber, and then add the solid content.
4 parts of the same dimethylpolysiloxane as in Example 1 was added and mixed to 100 parts, followed by pressure dehydration molding and drying at 130° C. for 13 hours to obtain a molded product. Table 3 shows the physical properties of the molded product obtained. Further, the obtained molded body was crushed and immersed in n-hexane, but no silicone oil was extracted at all.

[Table] Example 4 56.9 parts of silica powder and 43.4 parts of quicklime (CaO/
SiO ₂ molar ratio = 0.83) was suspended in water so that the water to solid content ratio was 12 to prepare a raw material slurry, and this was stirred in an autoclave at a pressure of 8 Kg/cm ² and a temperature of 175°C. A hydrothermal reaction was carried out for a period of time to obtain a crystalline aqueous slurry of approximately spherical secondary particles of zonolite crystals with a diameter of 10 to 150 μm. To 100 parts (solid content) of the crystal slurry obtained above,
5 parts of glass fiber and 3 parts of pulp were added and mixed as an aqueous suspension, and then 4.5 parts of dimethylpolysiloxane ("SH200 Oil" 500cs manufactured by Toray Silicone Co., Ltd.) was added to 100 parts of the solid content and mixed thoroughly. . Then, it was subjected to pressure dehydration molding and dried at 130° C. for 13 hours to obtain a molded product. Table 4 shows the physical properties of these molded bodies. Further, the obtained molded body was crushed and immersed in n-hexane, but no silicone oil was extracted at all.

[Table] Example 5 52 parts of silica powder, 45.5 parts of milk of lime with a sedimentation volume of 46 ml as CaO (CaO/SiO ₂ molar ratio = 1) was mixed with an amount of water such that the water-to-solids ratio was 24. The raw material slurry was adjusted to a pressure of 12Kg/cm ² and a temperature of 191
A hydrothermal reaction was carried out for 8 hours with stirring in an autoclave at
A crystal slurry in which approximately spherical secondary particles of ~80 μm were dispersed in water 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 3 parts of dimethylpolysiloxane ("SH200 Oil" 500cs, manufactured by Toray Silicone Co., Ltd.) was added to 100 parts of the solid content and mixed thoroughly. . Then, it was subjected to pressure dehydration molding and dried at 130° C. for 13 hours to obtain a molded product. Table 5 shows the physical properties of the molded product obtained. Further, the obtained molded body was crushed and immersed in n-hexane, but no silicone oil was extracted at all.

[Table] Test Example 1 In Example 1 and Comparative Example 1, the characteristics of the molded bodies were investigated when the thickness of the molded bodies was 10 mm. The results are shown in the table below. In addition, in Example 1 (No. 1), the amount of "SH200 oil" added was 4 parts, and in Comparative Example 1 (No. 2 and No. 3), the amount of "SM8706" emulsion added was 4 parts. and 10 parts.

[Table] As a result, in No. 2 in which silicone oil was used as an emulsion, the content in the center was significantly lower, and the content ratio was also much more than 4 times. In addition, in No. 3 in which silicone oil was added as an emulsion and the content in the center was 0.5% by weight, the content in the outer periphery was extremely large, and the content ratio was 4% as in No. 2. It was much more than double that. On the other hand, it can be seen that in No. 1, which is the molded article of the present invention, the content in the center and the content ratio can be maintained at constant values, and exhibits excellent water repellency and strength. Therefore, it can be seen that the molded article of the present invention can exhibit excellent water repellency and strength regardless of its thickness.

Claims (1)

[Scope of Claims] 1. A calcium silicate molded body substantially composed of interconnected secondary particles of calcium silicate crystals and containing a fibrous material and silicone oil, wherein the silicone oil is a core molded body. Even if the silicone oil is immersed in n-hexane, it exists bound to calcium silicate crystals from the outer periphery to the center of the molded product in a state that is not substantially extracted, and the silicone oil content in the center of the molded product is at least 0.5% by weight
A calcium silicate molded body having water repellency, characterized in that the ratio (weight) of the silicone oil content in the outer periphery of the molded body to the silicone oil content in the center of the molded body is 4 times or less. 2. The water-repellent calcium silicate molded body according to claim 1, wherein the silicone oil content in the center of the molded body is at least 1% by weight. 3. The water-repellent calcium silicate molded article according to claim 1, wherein the silicone oil content in the center of the molded article is at least about 1.5% by weight. 4. Calcium silicate having water repellency as set forth in claim 1, wherein the ratio (weight) of the silicone oil content in the outer circumference of the molded body to the silicone oil content in the center of the molded body is 2 times or less. Molded object.