Xonotlite-based calcium silicate molded body

Abstract

To provide a calcium silicate molded body in which heating shrinkage is hardly caused even in a high temperature range.SOLUTION: A xonotlite-based calcium silicate molded body of the present invention is a calcium silicate molded body that contains xonotlite, wherein the crystallite size of the (400) plane measured by powder X-ray diffraction is 40 nm or more. It is preferable that the xonotlite is derived from a siliceous component and a calcareous component, and the siliceous component is at least one selected from the group consisting of quartz and rice husk ash. In the xonotlite-based calcium silicate molded body of this invention, heating shrinkage is hardly caused even in a high-temperature range.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a xonotlite-based calcium silicate shaped body. [Background technology]

[0002] Since xonotlite-based calcium silicate molded bodies have excellent properties such as mechanical strength, fire resistance, non-combustibility, and heat resistance, and can be easily used industrially, they are used in a variety of applications and are highly valuable, for example, in various building materials such as roofing materials, ceiling materials, wall materials, and floor materials.

[0003] For example, Patent Document 1 discloses a technique for producing a calcium silicate-based molded body using a raw material containing calcium silicate hydrate mainly composed of xonotlite, etc. Such a calcium silicate-based molded body can have both heat resistance and acid resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-213581 A Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in recent years, there are many demands for further improvement in the functions of calcium silicate molded bodies, for example, further reduction in the heat shrinkage rate in high temperature ranges (e.g., 1100° C.) In particular, since conventional calcium silicate molded bodies tend to shrink easily above 1000° C., it is expected that improving the heat resistance of calcium silicate molded bodies will lead to development into new applications.

[0006] The present invention has been made in view of the above, and has an object to provide a calcium silicate molded body which is less susceptible to thermal shrinkage even in high temperature regions. [Means for solving the problem]

[0007] As a result of extensive research into achieving the above-mentioned objective, the inventors discovered that the above-mentioned objective can be achieved by using xonotlite, in which the crystallite size of the (400) plane is controlled to a specific size, as the main component, and thus completed the present invention.

[0008] That is, the present invention includes, for example, the subject matter described in the following sections. Item 1 A calcium silicate shaped body containing xonotlite, The xonotlite is a xonotlite-based calcium silicate molding having a crystallite size of 40 nm or more in the (400) plane as measured by powder X-ray diffraction method. Section 2 The xonotlite is derived from a siliceous component and a calcareous component, Item 2. The xonotlite-based calcium silicate shaped body according to Item 1, wherein the siliceous component is at least one selected from the group consisting of silica stone and rice husk ash. Section 3 Item 3. The xonotlite-based calcium silicate shaped body according to item 1 or 2, wherein the crystallite size of the (400) plane is 60 nm or less. Section 4 Item 1 or 2, a method for producing a xonotlite-based calcium silicate molded body, A manufacturing method comprising a step of obtaining xonotlite-based calcium silicate using raw materials containing a siliceous component, a calcareous component and water. Effect of the Invention

[0009] The xonotlite-based calcium silicate molded body of the present invention is unlikely to undergo heat shrinkage even in a high temperature range. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expressions "containing" and "comprise" include the concepts of "containing", "comprises", "consists essentially of" and "consists only of".

[0011] The xonotlite-based calcium silicate molded body of the present invention contains calcium silicate, and the xonotlite has a crystallite size of 40 nm or more in the (400) plane as measured by powder X-ray diffraction. This makes the xonotlite-based calcium silicate molded body of the present invention less susceptible to thermal shrinkage even in high temperature regions, and for example, even when heated in a 1100°C atmosphere for 24 hours, the molded body is less susceptible to shrinkage.

[0012] The crystallite size of the (400) plane of the xonotlite can be measured by powder X-ray diffraction. Specifically, the crystallite size of the (400) plane of the xonotlite can be derived based on the peak intensity (peak intensity observed at 2θ=20.9°±0.5) derived from the (400) crystal in the X-ray diffraction spectrum obtained by powder X-ray diffraction of the xonotlite-based calcium silicate. In this specification, the crystallite size refers to the one calculated by Scherrer's formula (the following formula (1)). D = Kλ / (βcosθ) (1) In formula (1), “D” represents the crystallite size. "K" indicates the Scherrer constant. In this embodiment, "K=1.05" is used. "λ" indicates the wavelength of X-rays. In this embodiment, "λ=0.154" is used. "β" indicates the half-width of the diffraction line. "θ" is the Bragg angle. In addition, "β" and "θ" are obtained from an X-ray diffraction (XRD) profile. For example, the XRD measurement may be performed using an XRD device "XRD-6100" manufactured by Shimadzu Corporation or an equivalent product. The conditions for the XRD measurement are, for example, as follows. X-ray source: Cu-Kα radiation (wavelength λ=0.154 nm) (monochromator) Tube voltage: 40kV Tube current: 30mA Measurement range: 2θ=20°~50° Scan speed: 0.25° / min Step width: 0.02° From the XRD profile, the half-width (β) of the 001,040,400 diffraction line and the Bragg angle (θ) of the 001,040,400 diffraction line are obtained. The values ​​of “λ”, “β” and “θ” are substituted into the above formula (1) to obtain the crystallite size.

[0013] If the crystallite size of the (400) plane is less than 40 nm, the shrinkage rate of the xonotlite-based calcium silicate molded body when heated in an atmosphere at 1100°C is large, and the heat resistance is poor. The crystallite size of the (400) plane is preferably 45 nm or more, more preferably 47 nm or more, even more preferably 49 nm or more, even more preferably 50 nm or more, and particularly preferably 51 nm or more. The crystallite size of the (400) plane is preferably 60 nm or less.

[0014] In the xonotlite-based calcium silicate molded body of the present invention, the crystallite size of the (400) plane of the xonotlite can be adjusted by various methods, and the methods are not particularly limited. For example, the crystallite size of the (400) plane can be adjusted by changing the production conditions of the xonotlite contained in the xonotlite-based calcium silicate molded body. One example of the adjustment method is a method of changing the conditions of the hydrothermal synthesis reaction described below that is carried out to produce the xonotlite-based calcium silicate.

[0015] In addition to the (400) plane, xonotlite may also have a (040) plane and a (001) plane. The crystallite size of the (040) plane is not particularly limited, and is, for example, 15 to 50 nm, and preferably 20 to 40 nm. The crystallite size of the (001) plane is not particularly limited, and is, for example, 10 to 40 nm, and preferably 15 to 35 nm. The (040) plane and the (001) plane are also measured by a powder X-ray diffraction method under the same conditions as described above.

[0016] The type of xonotlite contained in the xonotlite-based calcium silicate shaped body of the present invention is not particularly limited as long as it has the above-mentioned crystallite size. For example, the xonotlite is preferably derived from a siliceous component and a calcareous component. In other words, the calcium silicate preferably includes a product obtained by reacting a raw material containing a siliceous component with a raw material containing a calcareous component. Therefore, the xonotlite contained in the xonotlite-based calcium silicate shaped body is preferably produced using a raw material containing a siliceous component, a calcareous component, and water (hereinafter, the raw material is referred to as "raw material A").

[0017] Examples of the siliceous component include silica stone, silica sand, silica gel, white carbon, diatomaceous earth, ferrosilicon dust, shirasu, rice husk ash, etc. Silica stone is a mineral resource, and rice husk ash is a biomass resource.

[0018] Examples of the calcareous component include quicklime (calcium oxide), slaked lime (calcium hydroxide), carbide slag, calcium chloride, and the like.

[0019] In the raw material A, the content ratio of the siliceous component and the calcareous component is not particularly limited. For example, the content ratio of the siliceous component is preferably 40 to 60 mass%, more preferably 45 to 55 mass%, and further preferably 48 to 52 mass%, based on the total mass of the siliceous component and the calcareous component.

[0020] The water content in the raw material A is not particularly limited. The water content in the raw material A is 0.5 times or more, preferably 5 times or more, more preferably 10 times or more, and preferably 50 times or less, more preferably 30 times or less, and more preferably 25 times or less, based on the total mass of the siliceous component and the calcareous component.

[0021] It is also preferable that raw material A further contains an organic acid. By using raw material A containing an organic acid, the crystallite size of the (400) plane of the resulting xonotlite tends to be 40 nm or more.

[0022] The type of organic acid is not particularly limited, and may be a wide variety of known organic acids. The organic acid is preferably water-soluble, and may be acetic acid, lactic acid, citric acid, succinic acid, malic acid, diacetyltartaric acid, glycolic acid, glutaric acid, or the like. Among them, the organic acid is preferably citric acid. In this case, it is easier to control the crystallite size of the (400) plane to 40 nm or more. The organic acid contained in the raw material A may be one type alone or two or more types.

[0023] When raw material A contains an organic acid, its content is not particularly limited. In terms of ease of controlling the crystallite size of the (400) plane to 40 nm or more, the content ratio of the organic acid to the total mass of the siliceous component and the calcareous component contained in raw material A is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, even more preferably 0.5 mass% or more, and particularly preferably 0.8 mass% or more. In terms of ease of controlling the crystallite size of the (400) plane to 40 nm or more, the content ratio of the organic acid to the total mass of the siliceous component and the calcareous component contained in raw material A is preferably 10 mass% or less, more preferably 5 mass% or less, even more preferably 3 mass% or less, and particularly preferably 2 mass% or less.

[0024] Raw material A may further contain other components to the extent that the effects of the present invention are not impaired. Examples of other components include gypsum. When raw material A contains gypsum, the content of gypsum is 0.1 to 5 mass %, preferably 0.3 to 3 mass %, based on the total mass of the siliceous component and the calcareous component.

[0025] The method for obtaining xonotlite-based calcium silicate using raw material A is not particularly limited, and for example, a method similar to a known method for obtaining calcium silicate can be adopted. For example, xonotlite can be produced by a hydrothermal synthesis reaction of raw material A, and thus xonotlite-based calcium silicate can be obtained. The temperature of the hydrothermal synthesis reaction can be, for example, 175 to 260°C, and the pressure of the hydrothermal synthesis reaction can be, for example, 8 to 50 kgf / cm. 2 The hydrothermal synthesis reaction can be carried out, for example, in a known pressure-resistant vessel.

[0026] The time for the hydrothermal synthesis reaction is not particularly limited, and can be appropriately set depending on the temperature, etc. For example, the time for the hydrothermal synthesis reaction can be 1 to 20 hours, and is preferably 2 to 10 hours, and more preferably 3 to 7 hours, in that the crystallite size of the (400) plane can be easily controlled to 40 nm or more.

[0027] For example, an aqueous slurry containing xonotlite-based calcium silicate can be obtained by using the raw material A. Such xonotlite-based calcium silicate can be in the form of, for example, a hydrate.

[0028] Xonotlite is preferably derived from a siliceous component and a calcareous component, and the siliceous component is preferably at least one selected from the group consisting of silica stone and rice husk ash. In this case, xonotlite-based calcium silicate is easily produced, and calcium silicate having a crystallite size of 40 nm or more on the (400) plane is easily obtained.

[0029] The xonotlite (xonotlite-based calcium silicate) in the aqueous slurry obtained by using the raw material A may be in a state in which secondary particles are formed. The particle size of the secondary particles is not limited, and is, for example, about 5 to 150 μm.

[0030] The xonotlite-based calcium silicate shaped body of the present invention can be obtained by molding the xonotlite-based calcium silicate obtained using the raw material A. For example, the xonotlite-based calcium silicate shaped body can be obtained by dehydrating and molding the aqueous slurry containing the xonotlite. In other words, the xonotlite-based calcium silicate shaped body of the present invention can be obtained by a manufacturing method including a step of obtaining the xonotlite using raw materials containing a siliceous component, a calcareous component, and water.

[0031] The method for dehydrating and molding the aqueous slurry is not particularly limited, and for example, a wide variety of known dehydration and molding methods can be used.

[0032] When the aqueous slurry is dehydrated and molded, various additives can be added to the aqueous slurry as necessary, such as fibrous materials, cement, fillers, pigments, dyes, polymers (resins), flocculants, water repellents, etc.

[0033] Examples of the fibrous materials include known organic and inorganic fibers such as pulp, glass fiber, cotton, ceramic fiber, vinylon fiber, aramid fiber, nylon fiber, polyester fiber, polyethylene fiber, polypropylene fiber, steel fiber, and carbon fiber. Examples of cement include portland cement, white cement, alumina cement, blast furnace cement, fly ash cement, and mixed cement. Examples of fillers include clay, bentonite, talc, and calcium carbonate.

[0034] The content of the fibrous material can be, for example, 20 mass % or less, preferably 15 mass % or less, and more preferably 10 mass % or less, based on the total mass of solids in the aqueous slurry.

[0035] Examples of the method for dehydrating and molding the aqueous slurry include press dehydration molding, papermaking, roll dehydration molding, centrifugal molding, etc. The conditions for dehydration molding are not particularly limited, and known conditions can be widely adopted in the present invention.

[0036] After the dehydration molding, a drying treatment can be performed as necessary. A known method can be used for the drying treatment, and examples of the drying method include air drying, heat drying, hot air drying, vacuum drying, freeze drying, vacuum freeze drying, humidity-controlled drying, atmospheric control replacement drying, and supercritical drying. The drying temperature and degree of drying (moisture content) may be appropriately set depending on the composition, purpose, and use of the molded body.

[0037] The xonotlite-based calcium silicate shaped body of the present invention is obtained by dehydrating and molding the aqueous slurry. The xonotlite-based calcium silicate shaped body thus formed contains, for example, the above-mentioned calcium silicate secondary particles and / or compressed and deformed products of these secondary particles.

[0038] The content of xonotlite-based calcium silicate in the xonotlite-based calcium silicate shaped article of the present invention is, for example, 50 mass % or more, preferably 80 mass % or more, and more preferably 90 mass % or more.

[0039] The density of the xonotlite-based calcium silicate molded body of the present invention is not particularly limited. For example, the density of the xonotlite-based calcium silicate molded body of the present invention is 120 to 900 kg / m 3 The shape and size of the molded product are not particularly limited, and can be appropriately designed depending on the application.

[0040] The xonotlite-based calcium silicate molded body of the present invention contains calcium silicate having a (400) crystallite size of 40 nm or more as measured by powder X-ray diffraction. As a result, the xonotlite-based calcium silicate molded body of the present invention is unlikely to shrink even in high temperature regions, for example, even when heated in a 1100°C atmosphere for 24 hours.

[0041] However, naturally, the susceptibility of xonotlite-based calcium silicate molded bodies to heat shrinkage varies depending on the components other than xonotlite (for example, the type and presence or absence of additives). In this regard, in the present invention, when comparing xonotlite-based calcium silicate molded bodies of the same composition, a molded body containing calcium silicate with a crystallite size of 40 nm or more in the (400) plane is significantly more suppressed in heat shrinkage than a molded body containing a calcium silicate with a crystallite size of 40 nm or more in the (400) plane of xonotlite. In other words, when comparing xonotlite-based calcium silicate molded bodies of the same composition except for the different crystallite sizes in the (400) plane of xonotlite, the occurrence of heat shrinkage is significantly more suppressed in a molded body containing calcium silicate with a crystallite size of 40 nm or more in the (400) plane of xonotlite. EXAMPLES

[0042] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the embodiments of these examples.

[0043] Example 1 Raw material A was prepared by mixing 49 parts by mass of quicklime, 49.4 parts by mass of silica stone, 0.6 parts by mass of gypsum, and 1600 parts by mass of water, and further adding citric acid as an organic acid in an amount of 1% by mass based on the total mass of the quicklime and silica stone. This raw material A was mixed in an autoclave at a pressure of 14 kgf / cm 2 The mixture was stirred at 200°C for 5 hours to carry out a hydrothermal synthesis reaction. As a result, an aqueous slurry containing xonotlite-based calcium silicate was obtained. Next, 95 parts by mass of the aqueous slurry was prepared in terms of solid content, and 5 parts by mass of pulp was added to the aqueous slurry. The mixture was poured into a formwork and subjected to a pressure of 150 kgf / cm. 2 The resulting molded body was dried to obtain a xonotlite-based calcium silicate molded body.

[0044] Comparative Example 1 A xonotlite-based calcium silicate molded body was obtained in the same manner as in Example 1, except that raw material A was prepared without using citric acid.

[0045] Example 2 Raw material A was prepared by adding and mixing 47.2 parts by mass of quicklime, 51.2 parts by mass of rice husk ash, 0.6 parts by mass of gypsum, and 1600 parts by mass of water with citric acid as an organic acid at 1% by mass relative to the total mass of the quicklime and rice husk ash. This raw material A was heated in an autoclave at a pressure of 14 kgf / cm 2 The mixture was stirred at 200°C for 5 hours to carry out a hydrothermal synthesis reaction. As a result, an aqueous slurry containing xonotlite-based calcium silicate was obtained. Next, 95 parts by mass of the aqueous slurry was prepared in terms of solid content, and 5 parts by mass of pulp was added to the aqueous slurry. The mixture was poured into a formwork and subjected to a pressure of 150 kgf / cm. 2 The resulting molded body was dried to obtain a xonotlite-based calcium silicate molded body.

[0046] Comparative Example 2 A xonotlite-based calcium silicate molded body was obtained in the same manner as in Example 2, except that raw material A was prepared without using citric acid.

[0047] Example 3 A xonotlite-based calcium silicate molded body was obtained in the same manner as in Example 2, except that the hydrothermal synthesis reaction was carried out for 10 hours.

[0048] Comparative Example 3 A xonotlite-based calcium silicate molded body was obtained in the same manner as in Example 3, except that raw material A was prepared without using citric acid.

[0049] Example 4 Raw material A was prepared by adding and mixing 47.2 parts by mass of quicklime, 51.2 parts by mass of rice husk ash, 0.6 parts by mass of gypsum, and 1600 parts by mass of water with citric acid as an organic acid at 1% by mass relative to the total mass of the quicklime and rice husk ash. This raw material A was heated in an autoclave at a pressure of 14 kgf / cm 2The mixture was stirred at 200°C for 5 hours to carry out a hydrothermal synthesis reaction. As a result, an aqueous slurry containing xonotlite-based calcium silicate was obtained. Next, 95 parts by mass of the aqueous slurry was prepared in terms of solid content, and 2.6 parts by mass of pulp, 18.5 parts by mass of cement, and 4.4 parts by mass of glass fiber were added to the aqueous slurry. The mixture was poured into a formwork and subjected to a pressure of 150 kgf / cm. 2 The resulting molded body was dried to obtain a xonotlite-based calcium silicate molded body.

[0050] (Evaluation method) The powder X-ray diffraction method, the density of the molded body, the bending strength of the molded body, and the heat shrinkage rate were evaluated by the following methods.

[0051] <Powder X-ray diffraction method> In the powder X-ray diffraction method, an XRD device "XRD-6100" manufactured by Shimadzu Corporation was used. The conditions for the XRD measurement were as follows: X-ray source: Cu-Kα radiation (wavelength λ=0.154 nm) (monochromator) Tube voltage: 40kV Tube current: 30mA Measurement range: 2θ=20°~50° Scan speed: 0.25° / min Step width: 0.02°

[0052] <Molded object density> The molded bodies obtained in each of the Examples and Comparative Examples were dried at 105° C. until a constant weight was reached, and then the bone dry weight was measured. In addition, the dimensions of the length, width, and thickness were measured, and the following formula (2) was used. Molded body density (kg / m 3 ) = Bone dry weight / (length x width x thickness) (2) The density of the green body was determined from the above.

[0053] <Flexural strength of molded product> A test piece of 150 mm x 37 mm x 20 mm was cut out from the molded body obtained in each Example and Comparative Example to prepare a test specimen. This test specimen was placed on a support stand, and the pressure band in the center of the support distance (12 cm) was moved at a load speed of 10 to 30 mm / min to measure the force (maximum load) at which the test specimen broke. The force at which the specimen broke was defined as bending strength (N / cm 2 The bending strength was calculated using the following formula (3): Bending strength (N / cm 2 )=3·F·L / (2·b·t 2 ) (3) (F: Maximum load (N), L: Distance between supports (cm), b: Width of specimen (cm), t: Thickness of specimen (cm)) I asked for more.

[0054] <Heat shrinkage rate> Test pieces measuring 150 mm × 37 mm × 20 mm were cut out from the molded bodies obtained in each of the Examples and Comparative Examples, and these were placed in an electric furnace and heated to 1100° C. over 150 minutes, and then held at 1100° C. for 12 hours. Thereafter, the molded bodies were removed from the electric furnace, and the dimensions in the longitudinal direction were measured, and the heat shrinkage rates of the molded bodies were calculated using the following formula (4). Heat shrinkage rate (%) = {(dimension before heating - dimension after heating) / dimension before heating} x 100 (4)

[0055] Table 1 shows the evaluation results of the crystallite size of the (400) plane, the crystallite size of the (040) plane, the crystallite size of the (001) plane, the heat shrinkage rate (%), the density, and the bending strength of the xonotlite-based calcium silicate obtained in Example 1 and Comparative Example 1.

[0056] Except for the difference in the crystallite size of the (400) plane of xonotlite, Example 1 and Comparative Example 1 are xonotlite-based calcium silicate molded bodies having the same composition. Nevertheless, it can be seen from Table 1 that Example 1 is less susceptible to heat shrinkage than Comparative Example 1, even in the high temperature range.

[0057] [Table 1]

[0058] Table 2 shows the evaluation results of the (400) crystallite size, (040) crystallite size, (001) crystallite size, heat shrinkage rate (%), density, and bending strength of the xonotlite-based calcium silicate molded bodies obtained in Example 2 and Comparative Example 2.

[0059] Except for the difference in the crystallite size of the (400) plane of xonotlite, Example 2 and Comparative Example 2 are xonotlite-based calcium silicate molded bodies having the same composition. Nevertheless, it can be seen from Table 2 that Example 2 is less susceptible to heat shrinkage than Comparative Example 2, even in the high temperature range.

[0060] [Table 2]

[0061] Table 3 shows the evaluation results of the (400) crystallite size, (040) crystallite size, (001) crystallite size, heat shrinkage rate (%), density, and bending strength of the xonotlite-based calcium silicate molded bodies obtained in Example 3 and Comparative Example 3.

[0062] Except for the difference in the crystallite size of the (400) plane of xonotlite, Example 3 and Comparative Example 3 are xonotlite-based calcium silicate molded bodies having the same composition. Nevertheless, it can be seen from Table 3 that Example 3 is less susceptible to heat shrinkage than Comparative Example 3, even in the high temperature range.

[0063] [Table 3]

[0064] Table 4 shows the evaluation results of the (400) crystallite size, (040) crystallite size, (001) crystallite size, heat shrinkage rate (%), density, and bending strength of the xonotlite-based calcium silicate molded body obtained in Example 4.

[0065] [Table 4]

[0066] From the results of the above examples and comparative examples, it was found that xonotlite-based calcium silicate molded bodies containing xonotlite with a crystallite size of 40 nm or more on the (400) plane are less likely to undergo heat shrinkage even in high temperature regions.

Claims

1. A calcium silicate shaped body containing xonotlite, The xonotlite is a xonotlite-based calcium silicate shaped body having a crystallite size of the (400) plane of 40 nm or more as measured by powder X-ray diffraction method.

2. The xonotlite is derived from a siliceous component and a calcareous component, 2. The xonotlite-based calcium silicate shaped body according to claim 1, wherein the siliceous component is at least one selected from the group consisting of silica stone and rice husk ash.

3. 3. The xonotlite-based calcium silicate shaped body according to claim 1, wherein the crystallite size of the (400) plane is 60 nm or less.

4. A method for producing the xonotlite-based calcium silicate molded body according to claim 1 or 2, comprising the steps of: A manufacturing method comprising a step of obtaining xonotlite-based calcium silicate using raw materials containing a siliceous component, a calcareous component and water.