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. Specifically provided is a calcium-based carbonate compound for an inorganic molded body, said calcium-based carbonate compound having a calcite crystal structure, an aragonite crystal structure, or a combination thereof, wherein aspect ratio of the average major diameter to the average minor diameter is 2-19, and the oil absorption capacity is 40-90 mL / 100 g.

Description

Calcium carbonate compounds for inorganic moldings

[0001] The present invention relates to a calcium carbonate compound for use in an inorganic molded body.

[0002] Inorganic molded bodies are molded bodies that are mostly composed of inorganic substances such as hydraulic materials and siliceous materials, and because they have properties such as fire resistance, light weight, high strength, and ease of work, they are widely used as exterior wall materials for houses, roof underlayment materials, eaves ceiling materials, etc.

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

[0004] As a technology for promoting the reuse of waste materials while improving fire resistance, which is one of the important safety features required for inorganic molded bodies, a technology has been proposed in which seawater residue, which is mainly composed of calcium carbonate and magnesium hydroxide and is by-produced in the process of removing carbonates from seawater during the process of producing magnesium hydroxide from seawater, is applied to a calcareous material (Japanese Patent Laid-Open Publication No. 2012-116685).

[0005] JP 2012-116685 A

[0006] However, even with the above techniques, undesirable thermal behavior such as warping and cracking may occur during heating, and it is therefore necessary to sufficiently suppress the thermal behavior of inorganic molded bodies when used as building materials.

[0007] Furthermore, carbon dioxide is becoming widely recognized as a greenhouse gas, and the reuse and reduction of carbon dioxide emissions as a secondary product from industrial processes has become an urgent issue.

[0008] An object of the present invention is to provide a calcium carbonate compound for inorganic moldings that can sufficiently reduce warping and cracking during heating when used in inorganic moldings as building materials.

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

[0010] In one embodiment, the present invention relates to a calcium carbonate compound for use in an inorganic formed body, which has a calcite-type crystal structure, an aragonite-type crystal structure, or a combination thereof, has an aspect ratio of an average major axis to an average minor axis of 2 or more and 19 or less, and has an oil absorption of 40 mL / 100 g or more and 90 mL / 100 g or less.

[0011] This calcium carbonate compound for inorganic molded bodies (hereinafter also referred to as "calcium carbonate compound") has a specific crystal structure, aspect ratio, and oil absorption capacity, and therefore can sufficiently reduce warping and cracking during heating when used in inorganic molded bodies. While the reason for this is unclear, it is speculated as follows. The inventors investigated the cause of the heating behavior and hypothesized that the degree of shrinkage of the heated surface was large, which caused cracks on the heated surface. They also hypothesized that the cracks on the heated surface were the cause of cracking and warping throughout the inorganic molded body. Furthermore, they found that the large temperature rise on the back surface (the surface opposite the heated surface) during heating may result in rapid temperature transfer from the heated surface to the back surface, causing thermal shock in the thickness direction, leading to warping and cracking throughout the inorganic molded body. After further investigation, the inventors discovered that blending a calcium carbonate compound with a high aspect ratio into an inorganic molded body can suppress both the shrinkage of the heated surface and the increase in back surface temperature during heating. The high aspect ratio calcium carbonate compound functions as a so-called reinforcing material, thereby suppressing shrinkage of the heated surface and preventing cracks. It also reduces warping during thermal shock. Furthermore, by incorporating a low thermal conductivity calcium carbonate compound, the insulating properties of the inorganic molded body in the thickness direction are improved, suppressing the rise in the backside temperature and thereby suppressing the occurrence of thermal shock. Additionally, the use of a calcium carbonate compound with high oil absorption improves the dispersibility and filling ability within the inorganic molded body, thereby suppressing the shrinkage of the heated surface and the rise in the backside temperature during heating to a higher degree. It is presumed that these combined effects prevent warping and cracking throughout the inorganic molded body.

[0012] In this specification, the term "calcium-based carbonate compound" refers to a compound containing calcium carbonate as a main component, which is a concept that allows the inclusion or coexistence of other subcomponents that may be incorporated during the manufacturing process, etc. The calcium carbonate content in the calcium-based carbonate compound is preferably 90 mass% or more. XRF (X-ray fluorescence analysis) can be suitably employed 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, which improves the dispersibility of the calcium carbonate compound in the inorganic molded body and enables the shrinkage of the heating surface and the increase in the back surface temperature during heating to be suppressed to a higher level.

[0014] In one embodiment, the mesopore volume of the calcium carbonate compound is 0.018 mm ３ / g or more 0.045mm ３ This allows the strength of the calcium carbonate compound at the particle level to be maintained regardless of its shape, and allows efficient suppression of shrinkage of the heating surface during heating when blended into the inorganic molded body.

[0015] In one embodiment, the average particle size of the calcium carbonate compound as measured by a laser diffraction method is preferably 1.1 μm or more and 12.5 μm or less in terms of suppressing shrinkage of the heating surface.

[0016] In one embodiment, the calcium carbonate compound preferably has an average major axis of 0.5 μm or more and 25 μm or less as determined by scanning electron microscopy. In another embodiment, the calcium carbonate compound preferably has a BET specific surface area of ​​1 m or less. ２ / g or more 10m ２ By satisfying these conditions alone or in combination, it is possible to suppress the shrinkage of the heated surface and the rise in temperature of the back surface during heating to a higher level.

[0017] In one embodiment, the calcium carbonate compound is preferably a synthetic calcium carbonate compound, which is a reaction product of calcium hydroxide and carbon dioxide. By using the synthetic calcium carbonate compound as the calcium carbonate compound, carbon dioxide generated secondarily in industrial processes can be reused, which can contribute to reducing carbon dioxide emissions throughout the entire industrial process.

[0018] 1 is a SEM photograph of a calcium carbonate compound of Example 1-1 of the present invention. 2 is a SEM photograph of a calcium carbonate compound of Example 1-2 of the present invention. 3 is a SEM photograph of a calcium carbonate compound of Example 1-3 of the present invention. 4 is a SEM photograph of a calcium carbonate compound of Comparative Example 1-1 of the present invention. 5 is a partial perspective view schematically showing a heating tester.

[0019] A calcium carbonate compound for an inorganic formed body according to one embodiment of the present invention will be described below, but the present invention is not limited to these embodiments.

[0020] <Calcium-based carbonate compound for inorganic formed body> As the crystal structure of the calcium-based carbonate compound, a calcite type, an aragonite type, or a combination thereof can be suitably adopted. In order to give the calcium-based carbonate compound the above aspect ratio, it is preferable that it contains at least an aragonite type crystal structure.

[0021] The aspect ratio of the average major axis to the average minor axis of the calcium carbonate compound is from 2 to 19, preferably from 2.5 to 17, and more preferably from 3 to 15. It has been found that shrinkage of the heated surface and an increase in the back surface temperature during heating can be suppressed. By setting the aspect ratio of the calcium carbonate compound within the above range, the calcium carbonate compound with a high aspect ratio effectively functions as a reinforcing material, suppressing shrinkage of the heated surface and an increase in the back surface temperature, thereby preventing warping and cracking throughout the inorganic molded body.

[0022] When the inorganic molded body is produced by a papermaking method, the aspect ratio of the calcium carbonate compound is preferably 4 or more and 19 or less, more preferably 6 or more and 18 or less, and even more preferably 8 or more and 17 or less.

[0023] When the inorganic molded body is produced by extrusion molding, the aspect ratio of the calcium carbonate compound is preferably 2 or more and 12 or less, more preferably 2.5 or more and 10 or less, and even more preferably 3 or more and 8 or less.

[0024] The calcium carbonate compound has an oil absorption of 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 of the calcium carbonate compound is within the above range, the dispersibility and fillability of the calcium carbonate compound can be improved, and as a result, shrinkage of the heating surface and an increase in the back surface temperature during heating can be suppressed to higher levels.

[0025] The apparent specific gravity of the calcium 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 carbonate compound within the above range, the dispersibility of the calcium carbonate compound in the inorganic molded body is improved, and shrinkage of the heating surface and rise in the back surface temperature during heating can be suppressed to higher levels.

[0026] In one embodiment, the mesopore volume of the calcium carbonate compound is 0.018 mm ３ / g or more 0.045mm ３ / g, and 0.019 mm ３ / g or more 0.042mm ３ / g, and more preferably 0.020 mm ３ / g or more 0.038mm ３ This makes it possible to maintain the strength of the calcium carbonate compound at the particle level regardless of its shape, and to efficiently suppress shrinkage of the heating surface during heating when blended into the inorganic molded body.

[0027] The average particle size of the calcium carbonate compound measured by a 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 improving the dispersibility of the calcium carbonate compound and efficiently suppressing shrinkage of the heating surface.

[0028] The average major axis of the calcium carbonate compound as observed with a 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 even more preferably 2 μm or more and 18 μm or less, which suppresses aggregation of the calcium carbonate compounds themselves or of the calcium carbonate compounds with other components, thereby enabling shrinkage of the heating surface and an increase in the back surface temperature during heating to be suppressed to higher levels.

[0029] The BET specific surface area of ​​the calcium carbonate compound is 1 m ２ / g or more 10m ２ / g or less, and ２ / g or more 9m ２ / g or less is more preferable, and ２ / g or more 8m ２ This makes it possible to improve the dispersibility of the calcium carbonate compound, and as a result, it is possible to suppress to a higher level the shrinkage of the heating surface and the rise in the temperature of the back surface during heating.

[0030] In the X-ray diffraction measurement of the calcium carbonate compound, the peak intensity I of aragonite ａ Calcite peak intensity I ｃ Ratio to I ａ / I ｃ is preferably 0.02 or more, more preferably 0.20 or more, and even more preferably 1.00 or more, whereby a high aspect ratio can be efficiently imparted to the calcium carbonate compound, and the occurrence of warping and cracking of the inorganic molded body can be reduced to a higher level.

[0031] The calcium-based carbonate compound is preferably a synthetic calcium-based carbonate compound. By using a synthetic calcium-based carbonate compound that is a reaction product of calcium hydroxide and carbon dioxide as the calcium-based carbonate compound, carbon dioxide that is secondarily generated in the industrial process 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-based carbonate compound that is by-produced in the process of removing carbonates from seawater and seawater residue containing magnesium hydroxide as its main components can also be used as a calcium-based carbonate compound source.

[0032] (Method for producing calcium carbonate compound) The method for synthesizing a calcium carbonate compound is not particularly limited, and known production methods can be used. Typically, a carbon dioxide gas method is preferred in which carbon dioxide gas is blown into milk of lime (a slurry in which excess slaked lime is added to a saturated aqueous solution of slaked lime) to carbonate it. The carbon dioxide gas used in the carbon dioxide gas method can be the flue gas from a lime calciner, a boiler, a waste incinerator, or the like installed near a calcium carbonate compound production plant.

[0033] Known methods can also be used to impart a predetermined aspect ratio to a calcium carbonate compound based on the carbon dioxide gas method. Specific examples of such methods include a method for producing a calcium carbonate compound by adjusting the amount of carbon dioxide gas at each stage of the carbonation process, a method for producing a calcium carbonate compound by heating during the carbonation process, a method for producing a calcium carbonate compound by using needle-shaped light calcium carbonate compound as seed crystals in a slaked lime slurry and introducing carbon dioxide gas into the slurry to grow the seed crystals to a desired particle size through a carbonation reaction, a method for producing a calcium carbonate compound by adding an aragonite-type needle-shaped calcium carbonate compound to a slaked lime slurry and carrying out a carbonation reaction while stirring at a high stirring power, a method for producing an aragonite-type calcium carbonate compound by adding a phosphate compound, a method for producing a calcium carbonate compound by adding a sulfate compound to obtain a spindle-shaped calcium carbonate compound, a method for producing an aragonite-type calcium carbonate compound by using a slaked lime slurry prepared with an alkaline aqueous solution, and a method for producing an aragonite-type calcium carbonate compound by using a slaked lime slurry prepared with water containing magnesium ions. By using one or a combination of two or more of these methods, a calcium carbonate compound having an aragonite-type crystal structure can be efficiently produced.

[0034] Among these, a preferred method for producing a calcium carbonate compound having a high aspect ratio and oil absorption is a method for producing a calcium carbonate compound (hereinafter also referred to as a "seed crystal method") in which needle-shaped synthetic calcium carbonate compound having an aragonite-type crystal structure is used as seed crystals in a slaked lime slurry, carbon dioxide gas is introduced into the slurry, and the seed crystals are grown to a desired particle size by a carbonation reaction.

[0035] In the seed crystal method, the amount of the seed crystals to be added is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 5 parts by mass or more and 20 parts by mass or less, and even more preferably 8 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of slaked lime (calculated as CaO).

[0036] In the seed crystallization method, the concentration of carbon dioxide gas varies depending on the type of exhaust gas generated from each combustion engine, but is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 10% by volume or more, when carbonation efficiency is taken into consideration. The flow rate of carbon dioxide gas is preferably 10 L / min to 200 L / min, more preferably 30 L / min to 150 L / min, and even more preferably 60 L / min to 120 L / min, per 10 kg of the charged raw material CaO, when carbonation efficiency and production capacity are taken into consideration.

[0037] In the seed crystallization method, the carbonation temperature (the slurry temperature) is preferably 40°C or higher and 100°C or lower, more preferably 50°C or higher and 90°C or lower, and even more preferably 60°C or higher and 80°C or lower.

[0038] In the seed crystal method, it is preferable to allow carbonation to proceed in the presence of a phosphate. The phosphate is not particularly limited, but examples thereof 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.

[0039] In the seed crystal method, the amount of phosphate to be added is preferably 1 part by mass or more and 25 parts by mass or less, more preferably 4 parts by mass or more and 18 parts by mass or less, and even more preferably 6 parts by mass or more and 12 parts by mass or less, relative to 100 parts by mass of slaked lime (calculated as CaO).

[0040] If a high aspect ratio is not required, a calcium carbonate compound can also be produced without adding seed crystals or phosphate.

[0041] The produced calcium carbonate compound may be filtered and dried to obtain a powder, or may be used as a calcium carbonate compound source in the form of a slurry or cake without being filtered and dried.

[0042] In addition to the carbon dioxide gas method, a water utilization method is also preferred from the viewpoints of waste utilization and carbon dioxide reduction, in which magnesium hydroxide is removed from the residue (hereinafter referred to as "utilized water") by adding slaked lime or the like to seawater to produce magnesium hydroxide, and then an alkaline agent such as magnesium hydroxide is added to the residue (hereinafter referred to as "utilized water") and carbon dioxide gas is blown into the residue. Furthermore, as described above, in the process of producing magnesium hydroxide from seawater, calcium-based carbonate compounds by-produced in the process of removing carbonates from seawater and seawater residue mainly composed of magnesium hydroxide can also be used as the calcium-based carbonate compound source.

[0043] <Inorganic Molded Body> The inorganic molded body preferably contains a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium carbonate compound having a predetermined aspect ratio and oil absorption.

[0044] (Hydraulic Materials) Examples of hydraulic materials include cementitious materials, gypsum, lime, slag, etc. 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 alone or in combination of two or more.

[0045] The content of the hydraulic material is preferably 5% by mass or more and 45% by mass or less, more preferably 8% by mass or more and 42% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total amount of materials constituting the inorganic molded body. By setting the content of the hydraulic material within the above range, it is possible to improve the physical properties of the inorganic molded body, such as bending strength and peel strength, and to suppress an increase in the bulk specific gravity of the inorganic molded body, thereby improving workability during construction.

[0046] (Silicate Material) Examples of siliceous materials include silica sand, silica powder, silica fume, fly ash, diatomaceous earth, layered silicates (e.g., mica, talc, kaolin, bentonite), perlite, wollastonite, lightweight aggregates (e.g., fly ash balloons, perlite, shirasu balloons, glass foams, etc.), and other SiO２ These siliceous materials can be used alone or in combination of two or more. Talc, mica, and wollastonite can also be used as reinforcing fiber materials, which will be described later.

[0047] The content of the siliceous material is preferably 10% by mass or more and 55% by mass or less, more preferably 12% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less, based on the total amount of materials constituting the inorganic molded body. If the content of the siliceous material is within the above range, it becomes possible to set the bending strength, bulk specific gravity, water absorption rate, dimensional stability, etc. of the inorganic molded body within the desired range. In addition, as the siliceous material, perlite, fly ash balloons, shirasu balloons, etc., having a unit volume mass of 0.5 g / cm ３ When blending the following lightweight aggregates, in order to prevent the bulk density from becoming too light and weakening strength such as bending strength and peel strength, it is preferable to use other siliceous materials in combination so that the content of lightweight aggregate is 20 mass% or less, based on the total amount of materials constituting the inorganic molded body.

[0048] (Reinforcing Fiber Material) Examples of reinforcing fiber materials that can be used include pulps such as softwood pulp, hardwood pulp, fibrillated pulp thereof, and pulp obtained by defibrating waste paper, organic reinforcing fiber materials such as vinylon fiber, acrylonitrile fiber, and polypropylene fiber, and inorganic reinforcing fiber materials such as rock wool and glass fiber. These reinforcing fiber materials can be used alone or in combination of two or more.

[0049] In order to improve the strength and toughness of the inorganic molded body, the content of the reinforcing fiber material is preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 26% by mass or less, and even more preferably 4% by mass or more and 22% by mass or less, based on the total amount of materials constituting the inorganic molded body. By setting the content of the reinforcing fiber material within the above range, it is possible to exhibit a sufficient reinforcing effect while suppressing the protrusion of fibers on the surface of the inorganic molded body, thereby improving smoothness. When an inorganic reinforcing fiber material having an average length of 1 mm to 50 mm is blended as a reinforcing fiber material, in order to improve the smoothness of the inorganic molded body, it is preferable to use other reinforcing fiber materials in combination so that the content is 10% by mass or less, based on the total amount of materials constituting the inorganic molded body.

[0050] (Calcium-Based Carbonate Compound) As the calcium-based carbonate compound, the above-mentioned calcium-based carbonate compounds for inorganic formed bodies can be suitably used.

[0051] The content of the calcium carbonate compound is preferably 5% by mass or more and 60% by mass or less, more preferably 8% by mass or more and 55% by mass or less, and even more preferably 12% by mass or more and 50% by mass or less, based on the total amount of materials constituting the inorganic molded body. By blending a low-thermal-conductivity calcium carbonate compound in a content within the above range, the insulating properties in the thickness direction of the inorganic molded body are improved, and the rise in the back surface temperature is suppressed, thereby suppressing the occurrence of thermal shock. As a result, warping and cracking can be prevented throughout the inorganic molded body.

[0052] (Optional Components) In addition to the above-mentioned materials, various materials such as hollow resin bodies, wood chips, wood flour, resin powder, antifoaming agents, flocculants, water repellents, thickeners (methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.), dispersants, etc. can be blended into the inorganic molded body depending on the purpose in order to impart various functions. It is also possible to appropriately add recycled materials obtained by crushing scraps generated during processing of the inorganic molded body.

[0053] (Method for manufacturing inorganic molded body) The method for manufacturing the inorganic molded body according to this embodiment is not particularly limited, and commonly used methods such as papermaking, extrusion molding, flow-on molding, casting molding, and press (compression) molding can be used. The inorganic molded body can be obtained by subjecting a green sheet molded by these methods to a patterning process such as press dehydration or embossing, followed by curing at room temperature, steam curing, autoclave curing, or the like. The product may then be dried and, if necessary, shaped or painted.

[0054] (Uses of inorganic molded body) The uses of the inorganic molded body are not particularly limited, and it can be suitably used as a performance maintaining material such as a wall material, a floor material, a roofing material, various boards, external decorative members, interior and exterior finishing materials such as building materials, sealing materials, heat insulating materials, sound absorbing materials, waterproofing materials, etc. The inorganic molded body is preferably a cement-based molded body containing a cementitious material, and more preferably a calcium silicate molded body. Among them, the molded body is more preferably a molded board.

[0055] 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 is composed of a powder containing, in addition to calcium carbonate, at least one of blast furnace slag, an expansive agent, slaked lime, quicklime, fly ash, and a cementitious material. The calcium carbonate may be the calcium carbonate compound described above. The cementitious material may be the cementitious material described above for the hydraulic material.

[0056] In addition to the hydraulic composition, aggregates such as sand and gravel, chemicals such as chemical admixtures for concrete, and fiber materials made of metals or polymeric materials may be blended to form a hydraulic composition mixture.

[0057] The hardened hydraulic composition is obtained by hardening a paste obtained by kneading the hydraulic composition with water, and the hardened hydraulic composition mixture is obtained by hardening a mixture (equivalent to fresh mortar or fresh concrete) obtained by kneading the hydraulic composition mixture with water, and corresponds to mortar or concrete.

[0058] The present invention will be described in detail below using examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. Measurements and evaluations of physical properties, etc. were carried out as follows.

[0059] <Evaluation of calcium carbonate compounds> The calcium carbonate compounds obtained in each production example were analyzed as follows. The results of each analysis are shown in Table 1 and Figures 1 to 4.

[0060] (1) BET Specific Surface Area A sample powder was pretreated in a nitrogen gas atmosphere at about 130°C for about 30 minutes using an 8-tube preheat unit (manufactured by MOUNTECH Co., Ltd.), and the BET specific surface area (m ２ / g) was measured.

[0061] (2) Average particle size by laser diffraction method 50 mL of ethanol was placed in a 100 mL beaker, and about 0.2 g of the sample powder was placed in the 100 mL beaker. The mixture was subjected to ultrasonic treatment (UD-201, manufactured by Tomy Seiko Co., Ltd.) for 3 minutes to prepare a dispersion. This dispersion was measured using a laser diffraction particle size distribution analyzer (Microtrac HRA Model 9320-X100, manufactured by Nikkiso Co., Ltd.) to determine the volumetric D ５０ The value was measured as the average particle diameter (μm).

[0062] (3) 46° (aragonite) peak intensity I by XRD measurement ａ 29° (calcite) peak intensity I ｃ The sample powder was pressed and fixed onto a predetermined sample stage with a spatula, and then measured using an XRD device (MiniFlex600-C manufactured by Rigaku Corporation) to perform an identification analysis as a crystalline substance. Note that, 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 29° (calcite) peak intensity I ｃ Ratio to (I ａ / I ｃ ) was sought.

[0063] (4) Calculation of Average Long Diameter, Average Short Diameter, and Aspect Ratio by Scanning Electron Microscopy. Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied by tracing it with a spatula. After platinum deposition, particle images of the sample powder were photographed at 2,000 magnifications using a scanning electron microscope (FE-SEM: S-4700, manufactured by Hitachi, Ltd.). Figures 1 to 4 show SEM images. Using image analysis software (Image J), ​​20 particles were randomly selected from the SEM images, and the average long diameter, short diameter, and aspect ratio (ratio of long diameter to short diameter) of the primary particles were calculated. Specifically, the long diameter and short diameter were measured using the following procedure. For a randomly selected particle image, the length of the line with the greatest span was defined as the "long diameter," and the span on the particle image of a line perpendicular to the long diameter axis at the center of the line giving the long diameter (long diameter axis) was defined as the "short diameter."

[0064] (5) Apparent Specific Gravity The apparent specific gravity of the sample powder was measured in accordance with JIS K6220.

[0065] (6) Oil Absorption: 2.00 g of sample powder was placed on a watch glass, and dioctyl phthalate (DOP) in a burette was added drop by drop while the mixture was kneaded with a spatula. Adding a single drop to the solidified, coagulated sample caused the sample to suddenly soften, at which point the process was stopped. The amount of oil (mL) used until final solidification was determined, and the oil absorption per 100 g of sample was calculated using the following formula: A = V ÷ S × 100, where A is the oil absorption (mL / 100 g), V is the amount of oil (mL) used until solidification, and S is the sample weight (g).

[0066] (7) Mesopore volume The mesopore volume was measured by the nitrogen adsorption method. First, as a pretreatment, a BELPREP-vac II (manufactured by Microtrac-Bell) was used to perform vacuum degassing at 120°C for 8 hours. Next, a BELSORP-mini II (manufactured by Microtrac-Bell) was used to measure the adsorption / desorption isotherm with nitrogen according to the constant volume method. The measurement conditions were as follows. Finally, the mesopore volume was calculated by the BJH method. The BJH method analyzed pore diameters of approximately 3.4 nm to approximately 200 nm. [Measurement conditions] Adsorption temperature: 77 K Saturated vapor pressure: measured Adsorbate cross-sectional area: 0.162 nm２ Adsorbate: Nitrogen Equilibrium waiting time: 500 seconds *1 *1: Waiting time after reaching adsorption equilibrium (state where pressure change during adsorption / desorption is below a specified value)

[0067] <Production of calcium-based carbonate compound> [Example 1-1] Calcium-based carbonate compound (aspect ratio 10.4) 6,980 g of slaked lime powder (calculated as CaO), 630 g of aragonite seed crystal powder, and 500 g of disodium hydrogen phosphate dodecahydrate were prepared and each was charged with stirring into a 220 L SUS vessel equipped with a baffle and previously filled with 180 L of water to prepare a mixed slurry of the raw materials. The mixture was then heated to 70°C and stirred at that temperature using a stirrer equipped with one turbine blade at a rotation speed of 150 rpm. A flue gas extraction pipe was connected to the exhaust outlet of a steam production boiler fueled by LNG, and a test blower was used to draw in the exhaust gas. ２ When measured using a concentration meter (XP-3140 manufactured by New Cosmos Electric Co., Ltd.), CO ２ The concentration was 10% by volume. The exhaust gas was introduced into the aforementioned 220-liter SUS vessel using a test blower at a rate of 100 L / min, and the reaction was carried out for 7 hours. The mixture was then 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 carbonate compound.

[0068] Example 1-2 Calcium-Based Carbonate Compound (Aspect Ratio 18.2) A sample powder of calcium-based carbonate compound was obtained by the same procedure as in Example 1-1, except that the amount of milk of lime was 3,400 g in terms of CaO, the amount of aragonite seed crystals obtained in Example 1-1 was 310 g, and the amount of disodium hydrogen phosphate dodecahydrate was 240 g.

[0069] Example 1-3 Calcium-Based Carbonate Compound (Aspect Ratio 2.7) A sample powder of calcium-based carbonate compound was obtained by the same procedure as in Example 1-1, except that 7,170 g of milk of lime (calculated as CaO) was prepared, aragonite seed crystals and disodium hydrogen phosphate dodecahydrate were not added, and the reaction temperature was set to 40°C.

[0070] Comparative Example 1-1 Calcium-Based Carbonate Compound (Aspect Ratio 1.2) 5940 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries, Ltd.: purity 99.8%) was poured into a 220 L SUS container with a baffle, which had been previously filled with 100 L of water, while stirring, to prepare a sodium carbonate aqueous solution. Meanwhile, 1000 L of water was placed in a 2000 L polyethylene container, and 6940 g of calcium chloride reagent (manufactured by Wako Pure Chemical Industries, Ltd.: purity 95%) was poured into the container while stirring to prepare a calcium chloride aqueous solution (Ca ２＋ A sample powder of a calcium carbonate compound was prepared by the same procedure as in Example 1-1, except that 100 L of the sodium carbonate aqueous solution was added all at once to the stirred calcium chloride aqueous solution, and the reaction was continued for about 30 minutes.

[0071]

[0072] <Production of inorganic molded body> Inorganic molded bodies were produced by papermaking and extrusion molding according to the following procedures. The amounts of the components used are all expressed in "parts by mass" unless otherwise specified. In the table below, "-" indicates that the corresponding component was not used.

[0073] [Production Example 1-1] Production of an inorganic molded body by papermaking The materials shown in Table 2 below were placed in a plastic container and stirred and mixed to obtain a raw material slurry. The calcium carbonate compound of Example 1-1 was used as the calcium carbonate compound. The raw material slurry was divided and placed in a filter lined with felt, and a laminate (long side 28 mm x short side 24 mm x thickness 14 mm) was produced while performing suction filtration using a vacuum pump. The laminate was removed from the filter and subjected to dehydration pressing. The thickness after pressing was 13 mm. After autoclave curing (curing pressure (gauge pressure) 9 kgf; curing time 12 hours), the pressed body was dried in a dryer (105°C) for 24 hours. Both sides were sanded with a sander to adjust the thickness to 12 mm, and an inorganic molded body was obtained.

[0074] [Production Example 1-2] Production of inorganic molded body by papermaking method An inorganic molded body 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.

[0075] [Production Example 1-3] Production of inorganic molded body by papermaking method An inorganic molded body 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.

[0076] Comparative Production Example 1-1 Production of Inorganic Molded Body by Papermaking Method An inorganic molded body 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.

[0077] Comparative Production Example 1-2: Production of inorganic molded body by papermaking method An inorganic molded body was obtained in the same manner as in Production Example 1-1, except that the materials shown in Table 2 below were used and no calcium carbonate compound was added.

[0078] Comparative Production Example 1-3: Production of inorganic molded body by papermaking method An inorganic molded body was obtained in the same manner as in Production Example 1-1, except that a calcium carbonate compound having 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.

[0079] [Production Examples 1-4 to 1-10] Production of inorganic molded bodies by papermaking method Inorganic molded bodies were obtained in the same manner as in Production Example 1-1, except that the materials shown in Table 3 below were used. For reference, Table 3 also lists the materials and evaluations of Production Examples 1-1 to 1-3 and Comparative Production Example 1-2.

[0080] <Evaluation of Inorganic Molded Articles> The inorganic molded articles produced by the papermaking method in the Production Examples and Comparative Production Examples were evaluated as follows. The results are shown in Tables 2 and 3.

[0081] (Bulk Density) The bulk density was measured in accordance with JIS A 5430.

[0082] (Heating Test) The heating test was performed using the following equipment and procedure. Figure 5 is a partial perspective view showing a schematic diagram of the heating tester. As shown in Figure 5, an electric heater was used as the heat source, and a refractory material was installed between the test specimen and the heat source to stabilize the temperature at around 900 °C, and the temperature of the backside of the test specimen was 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. Each thermocouple was also connected to a data logger. The distance between the heating surface of the test specimen and the heat source was fixed at approximately 70 mm.

[0083] The test procedure was as follows: (1) A scrap board was placed, and preheating was performed up to 902°C, followed by heating once. (2) After the temperature of the heated surface had dropped below 200°C, the test specimen was inserted. (3) A thermocouple was placed in the center of the back surface (top surface in the figure) of the test specimen, and a calcium silicate board (approximately 30 mm x 70 mm) and a weight were placed on top to secure it in place. (4) Heating was initiated, and the specimen was 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 of the electric heater was set to 902°C on the heated surface side, and was controlled by a temperature controller with a lower limit of 900°C. The data logger also measured the temperature 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 was also measured before the test). - Dimensions: The length and width of the back surface and heated surface were measured with vernier calipers. The area of ​​the heated surface (mm ２ ) was calculated, and the heated surface shrinkage (%) was calculated based on the following formula: Heating surface shrinkage (%) = {|S １ -S ０ | / S ０}×100 (in the formula, S ０ is the area of ​​the heating surface before the test, and S １ is the area of ​​the heated surface after the test.) Warpage: The test specimen was placed on an iron surface plate, and the height of the center of each side of the test specimen from the iron surface plate was measured with a thickness gauge, and the average value (mm) was calculated. This average value was taken as the warpage (mm) after heating.

[0084]

[0085]

[0086] The inorganic molded body of the manufacturing example was superior to the comparative manufacturing example in terms of heated surface shrinkage, back surface temperature rise, and post-heating warpage. Furthermore, the inorganic molded body of the manufacturing example did not develop cracks after heating (not shown).

[0087] [Production Example 2-1] Production of inorganic molded body by extrusion molding The materials shown in Table 4 below were charged into an omnimixer, and the raw materials were dry-mixed for 3 minutes. The calcium carbonate compound of 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 extrusion-molded using the Ishikawa extruder. This produced a molded body (long side 600 mm x short side 190 mm x thickness 13 mm). After obtaining the molded body, it was placed in a thermo-hygrostat set at 60°C / 98% and subjected to primary curing, and then the pressure was increased to 9 kgf and autoclave curing was performed for 12 hours. Both sides of the molded body were sanded with a sander to reduce the thickness to 12 mm, producing an inorganic molded body.

[0088] [Production Example 2-2] Production of inorganic molded body by extrusion molding method An inorganic molded body 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.

[0089] [Production Example 2-3] Production of inorganic molded body by extrusion molding method An inorganic molded body 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.

[0090] Comparative Production Example 2-1 Production of Inorganic Molded Body by Extrusion Molding Method An inorganic molded body was obtained in the same manner as in Production Example 2-1, except that the calcium carbonate compound of Comparative Example 1-1 was used as the calcium carbonate compound.

[0091] Comparative Production Example 2-2: Production of inorganic molded body by extrusion molding Using the materials shown in Table 4 below, an inorganic molded body was obtained in the same manner as in Production Example 2-1, except that no calcium carbonate compound was added.

[0092] Comparative Production Example 2-3: Production of inorganic molded body by extrusion molding An inorganic molded body was obtained in the same manner as in Production Example 2-1, except that a calcium carbonate compound having 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.

[0093] <Evaluation of Inorganic Molded Articles> The inorganic molded articles produced by extrusion molding in the Production Examples and Comparative Production Examples were evaluated as follows. The results are shown in Table 4.

[0094] (Bulk Density) The bulk density was measured in accordance with JIS A 5430.

[0095] (Three-point bending test) The three-point bending test was carried out in accordance with JIS A 5430. The results were used to calculate the strength (N / mm ２ )

[0096] (Heating test) Measurement was carried out in the same manner as in the papermaking method.

[0097]

[0098] The inorganic molded body of the Example was superior to the Comparative Example in both the heating surface shrinkage and the warpage after heating. Furthermore, the inorganic molded body of the Example did not develop cracks after heating (not shown).

Claims

1. having 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 being 2 or more and 19 or less, and an oil absorption amount of 40 mL / 100 g or more and 90 mL / 100 g or less calcium-based carbonate compound for an inorganic molded body.

2. The calcium-based carbonate compound for an inorganic molded body according to Claim 1, having an apparent specific gravity of 0.1 g / mL or more and 1.0 g / mL or less.

3. The mesopore volume is 0.018 cm ３ / g or more and 0.045 cm ３ / g, and the calcium-based carbonate compound for the inorganic molded body according to claim 1.

4. The calcium-based carbonate compound for an inorganic molded body according to Claim 1, having an average particle diameter by a laser diffraction method of 1.1 μm or more and 12.5 μm or less.

5. The calcium-based carbonate compound for an inorganic molded body according to Claim 1, having an average major axis by observation with a scanning electron microscope of 0.5 μm or more and 25 μm or less.

6. The BET specific surface area is 1 m ２ / g or more and 10 m ２ / g or less, the calcium-based carbonate compound for the inorganic molded body according to claim 1.

7. The calcium-based carbonate compound for an inorganic molded body according to Claim 1, wherein the calcium-based carbonate compound for an inorganic molded body is a synthetic calcium-based carbonate compound.

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