Calcium-based carbonate compound for inorganic molded body

Abstract

Provided is a calcium-based carbonate compound for an inorganic molded body, said compound being capable of sufficiently reducing cracking and warping during heating when used in an inorganic molded body that serves as a construction material. The calcium-based carbonate compound for an inorganic molded body has a calcite-type crystal structure, an aragonite-type crystal structure, or a combination thereof with an aspect ratio of the average major axis to the average minor axis of 2-19, an oil absorption amount of 40 mL / 100 g to 90 mL / 100 g, and a mesopore volume of 0.018 cm3 / g to 0.045 cm3 / g.

Description

Calcium-based carbonate compounds for inorganic molded products

[0001] This invention relates to calcium-based carbonate compounds for inorganic molded articles.

[0002] Inorganic molded products are molded products that are mostly composed of inorganic substances such as hydraulic materials and silicate materials. Because they possess properties such as fire resistance, light weight, high strength, and workability, they are widely used as exterior wall materials, roof underlayment materials, and soffit materials for houses and other buildings.

[0003] On the other hand, with the growing environmental awareness in recent years, attempts are being made to reuse by-products and by-generated energy such as waste, exhaust gas, and waste heat that are secondarily generated in industrial processes.

[0004] As a technology to improve fire resistance, one of the important safety properties required for inorganic molded bodies, while also promoting the reuse of waste, a technology has been proposed that applies seawater residue mainly composed of calcium carbonate and magnesium hydroxide, which are by-products in the process of removing carbonates from seawater during the process of producing magnesium hydroxide from seawater, to a calcareous material (Japanese Patent Publication No. 2012-116685).

[0005] Japanese Patent Publication No. 2012-116685

[0006] However, even with the aforementioned technology, undesirable heating behaviors such as warping and cracking may occur during heating, and it is necessary to sufficiently suppress the heating behavior of inorganic molded bodies as building materials.

[0007] Furthermore, carbon dioxide is increasingly recognized as a greenhouse gas, making the reuse and reduction of carbon dioxide emissions from industrial processes an urgent issue.

[0008] The present invention aims to provide a calcium-based carbonate compound for inorganic molded bodies that can sufficiently reduce warping and cracking during heating when used in inorganic molded bodies as building materials.

[0009] As a result of diligent research, the inventors of the present invention have found that the above-mentioned problems can be solved by the following configuration, and have completed the present invention.

[0010] In one embodiment, the present invention provides a crystal having a calcite-type crystal structure, an aragonite-type crystal structure, or a combination thereof, with an aspect ratio of 2 to 19 between the average major axis and the average minor axis, an oil absorption capacity of 40 mL / 100 g to 90 mL / 100 g, and a mesopore volume of 0.018 cm³. ３ / g or more 0.045cm ３ This relates to a calcium-based carbonate compound for inorganic molded products, with a concentration of / g.

[0011] The calcium carbonate compound for inorganic molded articles (hereinafter also referred to as "calcium carbonate compound") has a specific crystal structure, aspect ratio, oil absorption capacity, and mesopore volume, and therefore can sufficiently reduce warping and cracking during heating when used in inorganic molded articles. Although the reason for this is not clear, it is presumed to be as follows. The inventors investigated the cause of the aforementioned heating behavior and considered that the degree of shrinkage of the heated surface was large, which may be causing cracks on the heated surface. It was also suspected that the cracks on the heated surface were inducing cracks and warping throughout the inorganic molded article. Furthermore, the inventors found that the large temperature rise on the back surface (the surface opposite to the heated surface) during heating meant that heat was rapidly transferred from the heated surface to the back surface, causing thermal shock in the thickness direction, which may be leading to the occurrence of warping and cracking throughout the inorganic molded article. As a result of further investigation, the inventors found that by incorporating a calcium carbonate compound with a high aspect ratio into the inorganic molded article, the shrinkage of the heated surface and the rise in the back surface temperature during heating can be suppressed, respectively. High aspect ratio calcium carbonate compounds function as reinforcing materials, suppressing shrinkage of the heated surface and preventing crack formation. They also reduce warping during thermal shock. Furthermore, incorporating low thermal conductivity calcium carbonate compounds enhances the heat insulation properties in the thickness direction of the inorganic molded body, suppressing the rise in back surface temperature and thus inhibiting thermal shock. Additionally, using high oil absorption calcium carbonate compounds improves dispersibility and filling properties within the inorganic molded body, resulting in a higher level of suppression of both heated surface shrinkage and back surface temperature rise during heating. Moreover, by limiting the mesopore volume of the calcium carbonate compound to a specific range, the particle-level strength of the calcium carbonate compound can be maintained regardless of its shape, efficiently suppressing heated surface shrinkage during heating when incorporated into the inorganic molded body. These combined effects are presumed to prevent warping and cracking of the entire inorganic molded body.

[0012] In this specification, "calcium-based carbonate compound" refers to a compound whose main component is calcium carbonate, and is a concept that allows for the inclusion or coexistence of other minor components that may be incorporated during the manufacturing process. Preferably, the calcium carbonate content in the calcium-based carbonate compound is 90% by mass or more. XRF (X-ray fluorescence analysis) can be suitably used as a method for measuring the calcium carbonate content in the calcium-based carbonate compound.

[0013] In one embodiment, the apparent specific gravity of the calcium carbonate compound is preferably 0.1 g / mL or more and 1.0 g / mL or less. This improves the dispersibility of the calcium carbonate compound in the inorganic molded body, and allows for a higher level of suppression of shrinkage of the heated surface and rise in the back surface temperature during heating.

[0014] In one embodiment, the average particle size of the calcium carbonate compound obtained by laser diffraction is preferably 1.1 μm or more and 12.5 μm or less, in terms of suppressing shrinkage of the heated surface.

[0015] In one embodiment, it is preferable that the average major axis of the calcium carbonate compound, as observed by scanning electron microscopy, is 0.5 μm or more and 25 μm or less. Also, in one embodiment, the BET specific surface area of ​​the calcium carbonate compound is 1 m². ２ / g or more 10m ２ It is preferable that the values ​​be less than or equal to / g. By satisfying these conditions individually or in combination, the shrinkage of the heating surface and the rise in the back surface temperature during heating can be suppressed to a higher level.

[0016] In one embodiment, the calcium carbonate compound is preferably a synthetic calcium carbonate compound. By using a synthetic calcium carbonate compound, which is a reaction product of calcium hydroxide and carbon dioxide, as the calcium carbonate compound, carbon dioxide generated secondarily in industrial processes can be reused, contributing to a reduction in carbon dioxide emissions throughout the industrial process.

[0017] This is an SEM image of the calcium carbonate compound of Example 1-1 of the present invention. This is an SEM image of the calcium carbonate compound of Example 1-2 of the present invention. This is an SEM image of the calcium carbonate compound of Example 1-3 of the present invention. This is an SEM image of the calcium carbonate compound of Comparative Example 1-1 of the present invention. This is a schematic partial perspective view of the heating tester.

[0018] A calcium-based carbonate compound for inorganic molded articles according to one embodiment of the present invention is described below. The present invention is not limited to these embodiments.

[0019] <Calcium-based carbonate compounds for inorganic molded articles> Suitable crystal structures for calcium-based carbonate compounds include calcite type, aragonite type, or combinations thereof. It is preferable that the calcium-based carbonate compound contains at least an aragonite type crystal structure, as this provides the aforementioned aspect ratio.

[0020] The aspect ratio of the average major diameter to the average minor diameter of the calcium carbonate compound is 2 to 19, preferably 2.5 to 17, and more preferably 3 to 15. Such calcium carbonate compounds are preferably spindle-shaped or needle-shaped. By keeping the aspect ratio of the calcium carbonate compound within the above range, the calcium carbonate compound with a high aspect ratio functions effectively as a reinforcing material, thereby suppressing shrinkage of the heated surface and rise in the back surface temperature, and preventing warping and cracking of the entire inorganic molded body.

[0021] When an inorganic molded body is produced by papermaking, the aspect ratio of the calcium carbonate compound is preferably 4 to 19, more preferably 6 to 18, and even more preferably 8 to 17.

[0022] When an inorganic molded body is produced by extrusion molding, the aspect ratio of the calcium carbonate compound is preferably 2 to 12, more preferably 2.5 to 10, and even more preferably 3 to 8.

[0023] The oil absorption amount of the calcium-based carbonate compound is preferably 40 mL / 100 g or more and 90 mL / 100 g or less, more preferably 45 mL / 100 g or more and 80 mL / 100 g or less, and even more preferably 50 mL / 100 g or more and 70 mL / 100 g or less. When the oil absorption amount of the calcium-based carbonate compound is within the above range, the dispersibility and filling property of the calcium-based carbonate compound can be improved. As a result, the shrinkage of the heating surface and the rise of the back surface temperature during heating can be suppressed at a higher level respectively.

[0024] The mesopore volume of the calcium-based carbonate compound is preferably 0.018 cm ３ / g or more and 0.045 cm ３ / g, more preferably 0.019 cm ３ / g or more and 0.042 cm ３ / g, and even more preferably 0.020 cm ３ / g or more and 0.038 cm ３ / g. Thereby, the strength at the particle level of the calcium-based carbonate compound can be maintained regardless of its shape, and the shrinkage of the heating surface during heating during blending into the inorganic molded body can be efficiently suppressed.

[0025] The apparent specific gravity of the calcium-based carbonate compound is preferably 0.1 g / mL or more and 1.0 g / mL or less, more preferably 0.2 g / mL or more and 0.9 g / mL or less, and even more preferably 0.3 g / mL or more and 0.8 g / mL or less. By setting the apparent specific gravity of the calcium-based carbonate compound within the above range, the dispersibility of the calcium-based carbonate compound in the inorganic molded body becomes good, and the shrinkage of the heating surface and the rise of the back surface temperature during heating can be suppressed at a higher level respectively.

[0026] The average particle diameter of the calcium-based carbonate compound by the laser diffraction method is preferably 1.1 μm or more and 12.5 μm or less, more preferably 1.5 μm or more and 12 μm or less, and even more preferably 2 μm or more and 10 μm or less. Thereby, the dispersibility of the calcium-based carbonate compound can be improved, and the shrinkage of the heating surface can be efficiently suppressed.

[0027] The average major axis of the calcium-based carbonate compound observed by scanning electron microscope is preferably 0.5 μm or more and 25 μm or less, more preferably 1 μm or more and 22 μm or less, and still more preferably 2 μm or more and 18 μm or less. Thereby, aggregation of the calcium-based carbonate compounds with each other or between the calcium-based carbonate compound and other components can be suppressed, and as a result, shrinkage of the heating surface and rise of the back surface temperature during heating can be suppressed at higher levels respectively.

[0028] The BET specific surface area of the calcium-based carbonate compound is preferably 1 m ２ / g or more and 10 m ２ / g or less, more preferably 2 m ２ / g or more and 9 m ２ / g or less, and still more preferably 3 m ２ / g or more and 8 m ２ / g or less. Thereby, the dispersibility of the calcium-based carbonate compound can be improved, and as a result, shrinkage of the heating surface and rise of the back surface temperature during heating can be suppressed at higher levels respectively.

[0029] In the X-ray diffraction measurement of the calcium-based carbonate compound, the ratio I ａ of the peak intensity I ｃ of aragonite to the peak intensity I ａ / I ｃ of calcite is preferably 0.02 or more, more preferably 0.20 or more, and still more preferably 1.00 or more. Thereby, a high aspect ratio can be efficiently imparted to the calcium-based carbonate compound, and warping and crack generation of the inorganic molded body can be reduced at a higher level.

[0030] The calcium carbonate compound is preferably a synthetic calcium carbonate compound. By using a synthetic calcium carbonate compound, which is a reaction product of calcium hydroxide and carbon dioxide, as the calcium carbonate compound, carbon dioxide secondarily generated in industrial processes can be reused, contributing to a reduction in carbon dioxide emissions throughout the industrial process. In addition, in the process of producing magnesium hydroxide from seawater, the calcium carbonate compound produced as a by-product in the process of removing carbonates from seawater and the seawater residue mainly composed of magnesium hydroxide can also be used as a source of calcium carbonate compounds.

[0031] (Method for producing calcium-based carbonate compounds) The method for synthesizing calcium-based carbonate compounds is not particularly limited, and known production methods can be used. Typically, the carbon dioxide method, in which carbon dioxide is blown into lime milk (a slurry obtained by adding an excess of slaked lime to a saturated aqueous solution of slaked lime) to carbonize it, is preferred. As the carbon dioxide used in the carbon dioxide method, exhaust gas from the flue of a lime calcination furnace, a boiler, a waste incinerator, etc., located in close proximity to the calcium-based carbonate compound production plant can be used.

[0032] Known methods can also be used to impart a predetermined aspect ratio to calcium carbonate compounds based on the carbon dioxide method. Specific examples of such methods include, for example, a method for producing calcium carbonate compounds in which the amount of carbon dioxide is adjusted at each stage of the carbonation process; a method for producing calcium carbonate compounds in which heating is performed at the carbonation stage; a method for producing calcium carbonate compounds in which needle-shaped light calcium carbonate compounds are used as seed crystals in a slaked lime slurry, carbon dioxide is introduced into the slurry, and the seed crystals are grown to a desired particle size by a carbonation reaction; a method for producing calcium carbonate compounds in which aragonite-type needle-shaped calcium carbonate compounds are added to a slaked lime slurry and a carbonation reaction is carried out while stirring with high stirring power; a method for producing aragonite crystalline calcium carbonate compounds by adding a phosphate compound; a method for producing calcium carbonate compounds in which a spindle-shaped calcium carbonate compound is obtained by adding a sulfate compound; a method for producing aragonite crystalline calcium carbonate compounds using a slaked lime slurry prepared with an alkaline aqueous solution; and a method for producing aragonite-type calcium carbonate compounds using a slaked lime slurry prepared with water containing magnesium ions. By using one or more of these methods in combination, calcium-based carbonate compounds containing an aragonite-type crystal structure can be efficiently produced.

[0033] In particular, as a method for producing calcium-based carbonate compounds having a high aspect ratio, oil absorption capacity, and a specific range of mesopore volume, a method is preferred in which a needle-shaped synthetic calcium-based carbonate compound with an aragonite-type crystalline structure is used as a seed crystal in a slaked lime slurry, and carbon dioxide is introduced into the slurry to grow the seed crystal to a desired particle size through a carbonation reaction (hereinafter also referred to as the "seed crystal method").

[0034] In the seed crystal method, the amount of seed crystal to be added is preferably 1 to 30 parts by mass, more preferably 5 to 20 parts by mass, and even more preferably 8 to 15 parts by mass, per 100 parts by mass of slaked lime (in terms of CaO).

[0035] In the seed crystallization method, the concentration of carbon dioxide varies depending on the type of exhaust gas generated from each combustion engine, but considering the carbonation efficiency, it is preferably 1 volume% or more, more preferably 5 volume% or more, and even more preferably 10 volume% or more. Regarding the flow rate of carbon dioxide, considering the carbonation efficiency and production capacity, it is preferably 10 L / min to 200 L / min per 10 kg of raw material CaO, more preferably 30 L / min to 150 L / min, and even more preferably 60 L / min to 120 L / min.

[0036] In the seed crystal method, the carbonation temperature (slurry temperature) is preferably 40°C to 100°C, more preferably 50°C to 90°C, and even more preferably 60°C to 80°C.

[0037] In the seed crystal method, it is preferable to allow carbonation to proceed in the presence of phosphates. The phosphates are not particularly limited, but examples include phosphoric acid, sodium dihydrogen phosphate anhydrous, sodium dihydrogen phosphate monohydrate, sodium dihydrogen phosphate dihydrate, disodium hydrogen phosphate dodecahydrate, potassium dihydrogen phosphate anhydrous, and ammonium dihydrogen phosphate anhydrous.

[0038] In the seed crystal method, the amount of phosphate added is preferably 1 to 25 parts by mass, more preferably 4 to 18 parts by mass, and even more preferably 6 to 12 parts by mass, per 100 parts by mass of slaked lime (in terms of CaO).

[0039] Furthermore, if a high aspect ratio is not required, calcium-based carbonate compounds can be manufactured without incorporating seed crystals or phosphates.

[0040] The generated calcium carbonate compound may be filtered and dried to obtain a powder, or it may be used as a source of calcium carbonate compound in slurry or cake form without filtering and drying.

[0041] In addition to the carbon dioxide method described above, the used water method, in which an alkaline agent such as magnesium hydroxide is added to the residue (hereinafter referred to as "used water") remaining after removing magnesium when producing magnesium hydroxide by adding slaked lime or the like to seawater, and then carbon dioxide is blown into it, is also preferable from the standpoint of waste utilization and reduction of carbon dioxide emissions. Furthermore, as mentioned above, in the process of producing magnesium hydroxide from seawater, the calcium carbonate compound produced as a by-product in the process of removing carbonates from seawater and the seawater residue mainly composed of magnesium hydroxide can also be used as a source of calcium carbonate compounds.

[0042] <Inorganic molded body> The inorganic molded body preferably contains a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium-based carbonate compound having a predetermined aspect ratio and oil absorption capacity.

[0043] (Hydraulic Materials) Examples of hydraulic materials include cementitious materials, gypsum, lime, and slag. Examples of cementitious materials include commonly used cements such as ordinary Portland cement, high-early-strength cement, moderate-heat cement, fly ash cement, blast furnace slag cement, and alumina cement. Examples of gypsum include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. Examples of slag include blast furnace slag and converter slag. These hydraulic materials can be used individually or in combination of two or more types.

[0044] The hydraulic material content is preferably 5% to 45% by mass, more preferably 8% to 42% by mass, and even more preferably 10% to 40% by mass, based on the total amount of materials constituting the inorganic molded body. By keeping the hydraulic material content within the above range, the physical properties of the inorganic molded body, such as bending strength and peel strength, can be improved, and the bulk density of the inorganic molded body can be suppressed, thereby improving workability during construction.

[0045] (Silicate materials) Examples of siliceous materials include silica sand, silica powder, silica fume, fly ash, diatomaceous earth, layered silicates (e.g., mica, talc, kaolin, bentonite), wollastonite, lightweight aggregates (e.g., fly ash balloons, perlite, shirasu balloons, glass foam, etc.), etc.２ Examples of materials containing a large amount of these materials include siliceous materials. These siliceous materials can be used individually or in combination of two or more. Talc, mica, and wollastonite can also be used as reinforcing fiber materials, as described later.

[0046] The silicate material content is preferably 10% to 55% by mass, more preferably 12% to 50% by mass, and even more preferably 15% to 45% by mass, based on the total amount of materials constituting the inorganic molded body. If the silicate material content is within the above range, it is possible to set the bending strength, bulk density, water absorption rate, dimensional stability, etc., of the inorganic molded body within the desired range. As the silicate material, perlite, fly ash balloons, shirasu balloons, etc., with a unit volume mass of 0.5 g / cm³ are preferred. ３ When incorporating the following lightweight aggregates, it is preferable to use other silicate materials in combination to prevent the bulk density from becoming too low and the strength, such as bending strength and peel strength, from weakening. The amount of lightweight aggregates should be 20% by mass or less, based on the total amount of materials constituting the inorganic molded body.

[0047] (Reinforcement Fiber Materials) As reinforcement fiber materials, for example, pulps such as softwood pulp, hardwood pulp, fibrillated pulp, and pulp obtained by defibrating recycled paper, organic reinforcement fiber materials such as vinylon fibers, acrylonitrile fibers, and polypropylene fibers, and inorganic reinforcement fiber materials such as rock wool and glass fibers can be used. These reinforcement fiber materials can be used individually or in combination of two or more types.

[0048] To improve the strength and toughness of the inorganic molded article, the content of reinforcing fiber material is preferably 2% to 30% by mass, more preferably 3% to 26% by mass, and even more preferably 4% to 22% by mass, based on the total amount of material constituting the inorganic molded article. By keeping the content of reinforcing fiber material within the above range, it is possible to improve the smoothness by suppressing the protrusion of fibers on the surface of the inorganic molded article while exhibiting a sufficient reinforcing effect. When incorporating inorganic reinforcing fiber material with an average length of 1 mm to 50 mm as the reinforcing fiber material, it is preferable to use other reinforcing fiber materials in combination so that the content of the reinforcing fiber material is 10% by mass or less, based on the total amount of material constituting the inorganic molded article, in order to improve the smoothness of the inorganic molded article.

[0049] (Calcium-based carbonate compounds) As the calcium-based carbonate compound, the above-mentioned calcium-based carbonate compounds for inorganic molded articles can be suitably used.

[0050] The content of the calcium carbonate compound is preferably 5% to 60% by mass, more preferably 8% to 55% by mass, and even more preferably 12% to 50% by mass, based on the total amount of material constituting the inorganic molded body. By incorporating a low thermal conductivity calcium carbonate compound in the above-mentioned range, the heat insulation in the thickness direction of the inorganic molded body is increased, and the rise in the temperature of the back surface is suppressed, thereby suppressing the occurrence of thermal shock. As a result, warping and cracking of the entire inorganic molded body can be prevented.

[0051] (Optional Components) In addition to the materials mentioned above, various materials such as hollow resin bodies, wood chips, wood powder, resin powder, defoamers, flocculants, water repellents, thickeners (methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, etc.), and dispersants can be added to the inorganic molded body according to the purpose in order to impart various functions. It is also possible to add recycled materials, such as crushed scraps generated during the processing of the inorganic molded body, as appropriate.

[0052] (Method for manufacturing inorganic molded articles) The method for manufacturing inorganic molded articles according to this embodiment is not particularly limited, and commonly used methods such as papermaking, extrusion molding, flow-on molding, pour molding, and press (compression) molding can be used. Inorganic molded articles can be obtained by molding green sheets using these methods, then dewatering them by press or embossing to create a pattern, and finally curing them at room temperature, with steam, or in an autoclave. Furthermore, drying may be performed, and shaping or painting may be carried out as needed.

[0053] (Uses of Inorganic Molded Articles) The uses of inorganic molded articles are not particularly limited and they can be suitably used as interior and exterior finishing materials such as wall materials, floor materials, roofing materials, various boards, exterior decorative members, and joinery, as well as as performance maintenance materials for sealing materials, heat insulating materials, sound absorbing materials, and waterproofing materials. The inorganic molded article is preferably a cement-based molded article containing cementitious material, and more preferably a calcium silicate molded article. Among these, the molded article is more preferably a molded board.

[0054] The inorganic molded body may be a concrete structure. The concrete structure is composed of a hardened body of a hydraulic composition. The hydraulic composition consists of a powder containing calcium carbonate, plus at least one of blast furnace slag, an expansive agent, slaked lime, quicklime, fly ash, and cementitious material. As the calcium carbonate, the aforementioned calcium-based carbonate compounds can be suitably used. As the cementitious material, the cementitious materials shown in the hydraulic material section can be suitably used.

[0055] In addition to the above-mentioned hydraulic composition, aggregates such as sand and gravel, chemical admixtures for concrete, and fibrous materials made of metals or polymers may be added to form a hydraulic composition mixture.

[0056] The hardened body of the hydraulic composition is obtained by hardening a paste made by mixing the hydraulic composition with water. Furthermore, the hardened body of the hydraulic composition mixture is obtained by hardening a mixture (equivalent to fresh mortar or fresh concrete) made by mixing the hydraulic composition mixture with water, and is equivalent to mortar or concrete.

[0057] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. The physical properties and other measurements and evaluations were performed as follows.

[0058] <Evaluation of Calcium-Based Carbonate Compounds> The calcium-based carbonate compounds obtained in each production example were analyzed as follows. The results of each analysis are shown in Table 1 and Figures 1-4.

[0059] (1) BET specific surface area The sample powder, pre-treated in a nitrogen gas atmosphere at approximately 130°C for approximately 30 minutes using an 8-unit preheating unit (manufactured by MOUNTECH), was measured using the nitrogen gas adsorption method with a Macsorb HM Model-1208 (manufactured by MOUNTECH) as the BET specific surface area measuring device, and the BET specific surface area (m²) was measured. ２ The amount (per g) was measured.

[0060] (2) Average particle size by laser diffraction method A dispersion was prepared by taking 50 mL of ethanol into a 100 mL beaker, adding approximately 0.2 g of sample powder to the aforementioned 100 mL beaker, and subjecting it to ultrasonic treatment for 3 minutes (Tommy Seiko UD-201). This dispersion was measured using a laser diffraction-particle size analyzer (Nikkiso Co., Ltd. Microtrac HRA Model 9320-X100) to determine the volume-based D ５０ The value was measured as the average particle diameter (μm).

[0061] (3) 46° (aragonite) peak intensity I measured by XRD ａ Peak intensity I of 29° (calcite) ｃ Calculation of the ratio to After compacting and fixing the sample powder onto a predetermined sample stage with a spatula, measurements were performed using an XRD device (MiniFlex 600-C manufactured by Rigaku Corporation) to identify and analyze the crystalline material. At a measurement angle 2θ, the peak appearing at approximately 29° is the main peak of calcite, and the peak appearing at approximately 46° is the main peak of aragonite. From this, the 46° (aragonite) peak intensity I ａ Peak intensity I of 29° (calcite) ｃ Ratio to (I ａ / I ｃ ) was sought.

[0062] (4) Calculation of average major axis, average minor axis and aspect ratio by scanning electron microscope observation Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied on top of it by tracing with a spatula. After platinum deposition, a 2000x magnification image of the sample powder particles was taken using a scanning electron microscope (FE-SEM: Hitachi, Ltd. S-4700). Figures 1 to 4 show the SEM images. Using image analysis software (Image J), ​​20 particles were randomly selected from the obtained SEM images, and the average values ​​of the major axis (μm), minor axis (μm), and aspect ratio (ratio of major axis to minor axis) of the primary particles were determined. Specifically, the measurement of the major axis and minor axis was performed using the following procedure. For one randomly selected particle image, the length of the line with the maximum span was defined as the "major axis," and the span of the line perpendicular to the major axis at the center of the line giving the major axis (major axis) on the particle image was defined as the "minor axis."

[0063] (5) Apparent specific gravity The apparent specific gravity of the sample powder was measured in accordance with JIS K6220.

[0064] (6) Oil absorption amount Take 2.00 g of sample powder and place it on a watch glass. Add dioctyl phthalate (DOP) from a burette drop by drop while kneading with a spatula. Add one drop to the agglomerated and solidified sample and stop when a sudden softening phenomenon occurs. Determine the amount of oil used until final solidification (mL), and calculate the amount of oil absorbed per 100 g of sample using the following formula: A = V ÷ S × 100 Here, A is the amount of oil absorbed (mL / 100 g), V is the amount of oil used until solidification (mL), and S is the amount of sample (g).

[0065] (7) Mesopore volume The mesopore volume was measured by the nitrogen adsorption method. First, as a pretreatment, vacuum degassing was performed at 120°C for 8 hours using BELPREP-vacII (Microtrac-Bell). Next, the nitrogen adsorption / desorption isotherm was measured using BELPREP-miniII (Microtrac-Bell) according to the constant volume method. The measurement conditions were as follows. Finally, the mesopore volume (cm) was measured by the BJH method. ３The amount (per g) was calculated. The BJH method was used to analyze pore diameters from approximately 3.4 nm to approximately 200 nm. [Measurement conditions] Adsorption temperature: 77 K Saturated vapor pressure: Measured Adsorbate cross-sectional area: 0.162 nm ２ Adsorbate: Nitrogen Equilibrium Waiting Time: 500 sec *1 *1: Waiting time after reaching the adsorption equilibrium state (the state in which the pressure change during adsorption and desorption falls below a predetermined value)

[0066] <Production of Calcium-Based Carbonate Compounds> [Example 1-1] Calcium-Based Carbonate Compound (Aspect Ratio 10.4) 6980 g of slaked lime powder (in terms of CaO), 630 g of aragonite seed crystal powder, and 500 g of disodium hydrogen phosphate dodecahydrate were prepared. Each of these was added under stirring to a 220 L capacity SUS container with baffles pre-filled with 180 L of water to prepare a raw material mixture slurry. The mixture was then heated to 70°C and stirred at a rotation speed of 150 rpm using a stirrer equipped with a single stage turbine blade. Exhaust gas extraction piping was connected to the exhaust outlet of a steam production boiler fueled by LNG, and while drawing in exhaust gas using a test blower, CO ２ When measured with a concentration meter (XP-3140 manufactured by Shin-Cosmos Electric Co., Ltd.), CO ２ The concentration was 10% by volume. Exhaust gas was introduced into the aforementioned 220 L capacity SUS container at a speed of 100 L / min using a test blower and the mixture was reacted for 7 hours. After that, it was filtered, washed with approximately five times the amount of water relative to the solid content, dried at 110°C for 24 hours, and pulverized to obtain a sample powder of a calcium-based carbonate compound.

[0067] [Example 1-2] Calcium-based carbonate compound (aspect ratio 18.2) A sample powder of a calcium-based carbonate compound was obtained by the same procedure as in Example 1-1, except that 3400 g of lime milk (calculated in terms of CaO), 310 g of the product obtained in Example 1-1 as a seed crystal of aragonite, and 240 g of disodium hydrogen phosphate dodecahydrate were used.

[0068] [Example 1-3] Calcium-based carbonate compound (aspect ratio 2.7) 7170 g of lime milk (calculated in terms of CaO) was prepared, while aragonite seed crystals and disodium hydrogen phosphate dodecahydrate were not added. The same procedure as in Example 1-1 was performed to obtain a sample powder of a calcium-based carbonate compound, except that the reaction temperature was set to 40°C.

[0069] [Comparative Example 1-1] Calcium-based carbonate compound (aspect ratio 1.2) 5940 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries: purity 99.8%) was added under stirring to a 220 L capacity SUS container with baffles pre-filled with 100 L of water to prepare an aqueous sodium carbonate solution. On the other hand, 1000 L of water was placed in a 2000 L capacity polyethylene container, and 6940 g of calcium chloride reagent (manufactured by Wako Pure Chemical Industries: purity 95%) was added under stirring to prepare an aqueous calcium chloride solution (Ca ２＋ A solution containing 0.25 g / dL was prepared. Then, a sample powder of the calcium carbonate compound was obtained by performing the same procedure as in Example 1-1, except that 100 L of the aforementioned sodium carbonate aqueous solution was added all at once while the calcium chloride aqueous solution was being stirred, and the reaction was carried out by continuing to stir for about 30 minutes.

[0070]

[0071] <Manufacturing of Inorganic Molded Articles> Inorganic molded articles were manufactured by papermaking and extrusion molding according to the following procedure. Unless otherwise specified, the amounts of the components used are all expressed in "parts by mass". In the table below, "-" indicates that the corresponding component was not used.

[0072] [Manufacturing Example 1-1] Manufacturing of an inorganic molded body by papermaking The materials shown in Table 2 below were placed in a poly container and stirred to obtain a raw material slurry. The calcium carbonate compound from Example 1-1 was used as the calcium carbonate compound. The raw material slurry was divided and placed into a filter lined with felt, and a laminate (28 mm long side x 24 mm short side x 14 mm thick) was produced by suction filtration using a vacuum pump. The laminate was removed from the filter and dewatered by pressing. The thickness after pressing was 13 mm. After autoclave curing (curing pressure (gauge pressure) 9 kgf; curing time 12 hr), the pressed body was dried in a dryer (105°C) for 24 hr. Both sides were polished with a sander to adjust the thickness to 12 mm to obtain an inorganic molded body.

[0073] [Production Example 1-2] Production of an inorganic molded article by papermaking method An inorganic molded article was obtained in the same manner as in Production Example 1-1, except that the calcium carbonate compound of Example 1-2 was used as the calcium carbonate compound.

[0074] [Production Example 1-3] Production of an inorganic molded article by papermaking method An inorganic molded article was obtained in the same manner as in Production Example 1-1, except that the calcium carbonate compound of Example 1-3 was used as the calcium carbonate compound.

[0075] [Comparative Production Example 1-1] Production of an inorganic molded article by papermaking method An inorganic molded article was obtained in the same manner as in Production Example 1-1, except that the calcium carbonate compound of Comparative Example 1-1 was used as the calcium carbonate compound.

[0076] [Comparative Manufacturing Example 1-2] Manufacturing of an inorganic molded article by papermaking method An inorganic molded article was obtained in the same manner as in Manufacturing Example 1-1, except that the materials shown in Table 2 below were used and calcium carbonate compounds were not added.

[0077] [Comparative Manufacturing Example 1-3] Manufacturing of an inorganic molded body by papermaking method. An inorganic molded body was obtained in the same manner as in Manufacturing Example 1-1, except that a calcium carbonate compound with an aspect ratio of 25 was used as the calcium carbonate compound. However, the calcium carbonate compound broke during molding and could not maintain its original shape, so no evaluation was performed.

[0078] [Manufacturing Examples 1-4 to 1-10] Manufacturing of inorganic molded articles by papermaking method. Inorganic molded articles were obtained in the same manner as in Manufacturing Example 1-1, except that the materials shown in Table 3 below were used. For reference, Table 3 also includes the materials and evaluations for Manufacturing Examples 1-1 to 1-3 and Comparative Manufacturing Example 1-2.

[0079] <Evaluation of Inorganic Molded Articles> The inorganic molded articles produced by the papermaking method in the production example and comparative production example were evaluated as follows. The results are shown in Tables 2 and 3.

[0080] (Bulk density) Bulk density was measured in accordance with JIS A 5430.

[0081] (Heating Test) The heating test was conducted using the following apparatus and procedure. Figure 5 is a schematic partial perspective view of the heating test apparatus. As shown in Figure 5, a refractory material was assembled between the test specimen and the heat source so that the temperature could be stabilized at around 900°C using an electric heater as the heat source, and the temperature on the back surface of the test specimen could be measured with a thermocouple. Specifically, an electric heater (1.2 kW heater) was used as the heat source equipment, and a K-type thermocouple and a temperature controller were connected to it. Each thermocouple was also connected to a data logger. The distance between the heated surface side of the test specimen and the heat source was fixed at approximately 70 mm.

[0082] The test procedure was as follows: (1) A sacrificial plate was placed and preheated to 902°C, after which heating was performed. (2) The test specimen was inserted after the heating surface had fallen below 200°C. (3) A thermocouple was placed in the center of the back surface (top surface in the diagram) of the test specimen, and a calcium silicate plate (approximately 30 mm x 70 mm) and a weight were placed on top and fixed in place. (4) Heating was started and left for a predetermined time (45 minutes), and the temperatures of the front and back surfaces were recorded with a data logger. During this time, the temperature setting of the electric heater was 902°C on the heating surface side, and controlled by a temperature controller with a lower limit of 900°C. The temperature measurement interval of the data logger was set to every 10 seconds, and data was recorded at this interval. (5) After the test was completed, the test specimen was removed and the following items were measured (each item had also been measured before the test): Dimensions: The length and width of the back surface and heating surface were measured with calipers. Area of ​​the heating surface (mm²) before and after the test. ２ The following formula was used to calculate the heat shrinkage (%): Heat shrinkage (%) = {|S１ -S ０ | / S ０}×100 (in the formula, S ０ This is the area of ​​the heated surface before the test, S １ ) This is the area of ​​the heated surface after the test. ・Warping: The test specimen was placed on an iron surface plate, and the height from the iron surface plate at the center of each side of the test specimen was measured with a thickness gauge, and the average value (mm) was taken. This average value was taken as the warping after heating (mm).

[0083]

[0084]

[0085] The inorganic molded article in the manufacturing example showed superior performance compared to the comparative manufacturing example in terms of heating surface shrinkage, back surface temperature rise, and post-heating warping. Furthermore, no cracks occurred in the inorganic molded article in the manufacturing example after heating (not shown).

[0086] [Manufacturing Example 2-1] Manufacturing of an inorganic molded body by extrusion molding The materials shown in Table 4 below were placed in an omnimixer and the raw materials were dry-mixed for 3 minutes. The calcium carbonate compound from Example 1-1 was used as the calcium carbonate compound. Next, water was added and wet-mixed for 2 minutes. The raw materials after wet mixing were kneaded in an Ishikawa extruder and then extruded in the Ishikawa extruder. This produced a molded body with dimensions of 600 mm (long side) x 190 mm (short side) x 13 mm (thickness). After obtaining the molded body, it was placed in a constant temperature and humidity chamber set to 60°C / 98% for primary curing, and then the pressure was increased to 9 kgf for 12 hours of autoclave curing. Both sides of the molded body were polished with a sander to a thickness of 12 mm to produce an inorganic molded body.

[0087] [Production Example 2-2] Production of an inorganic molded article by extrusion molding An inorganic molded article was obtained in the same manner as in Production Example 2-1, except that the calcium carbonate compound of Example 1-2 was used as the calcium carbonate compound.

[0088] [Production Example 2-3] Production of an inorganic molded article by extrusion molding An inorganic molded article was obtained in the same manner as in Production Example 2-1, except that the calcium carbonate compound of Example 1-3 was used as the calcium carbonate compound.

[0089] [Comparative Manufacturing Example 2-1] Production of an inorganic molded article by extrusion molding An inorganic molded article was obtained in the same manner as in Manufacturing Example 2-1, except that the calcium carbonate compound of Comparative Example 1-1 was used as the calcium carbonate compound.

[0090] [Comparative Manufacturing Example 2-2] Manufacturing of an inorganic molded article by extrusion molding. An inorganic molded article was obtained in the same manner as in Manufacturing Example 2-1, except that the materials shown in Table 4 below were used and calcium carbonate compounds were not added.

[0091] [Comparative Manufacturing Example 2-3] Manufacturing of an inorganic molded body by extrusion molding. An inorganic molded body was obtained in the same manner as in Manufacturing Example 2-1, except that a calcium carbonate compound with an aspect ratio of 25 was used as the calcium carbonate compound. However, the calcium carbonate compound broke during molding and could not maintain its original shape, so no evaluation was performed.

[0092] <Evaluation of Inorganic Molded Articles> The inorganic molded articles produced by the extrusion molding method in the production example and comparative production example were evaluated as follows. The results are shown in Table 4.

[0093] (Bulk density) Bulk density was measured in accordance with JIS A 5430.

[0094] (Three-point bending test) The three-point bending test was performed in accordance with JIS A 5430. The results were used to determine the strength (N / mm²) of the inorganic cement-based molded board. ２ )

[0095] (Heating test) Measurements were taken in the same manner as in the papermaking process.

[0096]

[0097] In the example inorganic molded article, both heating surface shrinkage and post-heating warping were superior to those in the comparative manufacturing example. Furthermore, no cracks were observed in the example inorganic molded article after heating (not shown).

Claims

1. It has a calcite-type crystal structure, an aragonite-type crystal structure, or a combination thereof, with an aspect ratio of 2 to 19 between the average major axis and the average minor axis, an oil absorption capacity of 40 mL / 100 g to 90 mL / 100 g, and a mesopore volume of 0.018 cm³. ３ / g or more 0.045cm ３ A calcium-based carbonate compound for inorganic molded products, with a concentration of / g.

2. The calcium-based carbonate compound for inorganic molded articles according to claim 1, wherein the apparent specific gravity is 0.1 g / mL or more and 1.0 g / mL or less.

3. The calcium-based carbonate compound for inorganic molded articles according to claim 1, wherein the average particle size determined by laser diffraction is 1.1 μm or more and 12.5 μm or less.

4. The calcium carbonate compound for inorganic molded articles according to claim 1, wherein the average major axis observed by scanning electron microscopy is 0.5 μm or more and 25 μm or less.

5. The BET specific surface area is 1 m² ２ / g or more 10m ２ A calcium-based carbonate compound for inorganic molded articles according to claim 1, wherein the amount is less than or equal to / g.

6. The calcium-based carbonate compound for inorganic molded articles according to claim 1, wherein the calcium-based carbonate compound for inorganic molded articles is a synthetic calcium-based carbonate compound.

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