Calcium-based carbonic acid compound and inorganic molded body

Abstract

Provided are: a calcium-based carbonic acid compound, the shape of which is controlled so as to have a high aspect ratio; and an inorganic molded body. The present invention provides a calcium-based carbonic acid compound wherein: the content of phosphorus atoms is 1,000-15,000 ppm; the content of sulfur atoms is 2,000 ppm or less; and the aspect ratio of the average major axis to the average minor axis is 6-19.

Description

Calcium carbonate compounds and inorganic moldings

[0001] The present invention relates to a calcium carbonate compound and 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 workability, they are widely used for exterior wall materials, roof underlayment materials, eaves ceiling materials, etc. of houses, etc. Calcium carbonate is sometimes blended into inorganic molded bodies with the aim of reducing carbon dioxide emissions and improving fire resistance.

[0003] On the other hand, due to 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 generated secondarily in industrial processes. A technology has been proposed in which carbon dioxide in exhaust gas is used to fix carbon dioxide during the production of calcium carbonate, and this calcium carbonate is incorporated into building materials (WO 2021 / 256484).

[0004] International Publication No. 2021 / 256484

[0005] In order to improve the functionality of inorganic molded bodies and other objects to which calcium carbonate is added, it is necessary to control the shape of calcium carbonate, particularly to increase its aspect ratio.

[0006] An object of the present invention is to provide a calcium carbonate compound and an inorganic molded body whose shape is controlled so as to have a high aspect ratio.

[0007] 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.

[0008] In one embodiment, the present invention relates to a calcium carbonate compound having a phosphorus atom content of 1,000 ppm or more and 15,000 ppm or less, a sulfur atom content of 2,000 ppm or less, and an aspect ratio of an average major axis to an average minor axis of 6 or more and 19 or less.

[0009] As a result of investigations, the present inventors have newly discovered that phosphorus atoms act as promoters of needle-like or rod-like shapes (hereinafter collectively referred to as "needle-like shapes, etc.") that result in high aspect ratios during crystal growth of calcium carbonate compounds, while sulfur atoms act as inhibitors of needle-like shapes, etc. The present inventors have developed this novel finding to complete the present invention. The calcium carbonate compounds have phosphorus and sulfur atom contents within specific ranges, allowing for highly controllable shape and a high aspect ratio.

[0010] 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% by mass or more. The calcium carbonate content in the calcium-based carbonate compound can be suitably measured by the ethylenediaminetetraacetic acid disodium titration method.

[0011] <Ethylenediaminetetraacetic acid disodium titration method> 1 g of calcium carbonate compound (dried for 2 hours at 105°C) was weighed as a sample and suspended in 50 mL of water. 10 mL of hydrochloric acid (a 1:1 mixture of concentrated hydrochloric acid and water by volume) was added and heated to dissolve. After cooling, the suspension was transferred to a 250 mL volumetric flask and made up to the same volume with water. A 5.00 mL aliquot was taken from this and water was added to bring the total volume to approximately 50 mL. 5 mL of buffer solution (a 1,000 mL solution prepared by dissolving 500 g of potassium hydroxide in water) was added, followed by commercially available Dotite NN diluted powder. The titration was terminated when the solution changed color from red to blue. The calcium carbonate content (%) was calculated using the following formula:

[0012] (In the formula, f is the factor of the titration reagent. The factor is determined by standardization with the titration reagent using a BT indicator. V is the amount of titration reagent consumed (mL). W is the amount of sample taken (0.02 g of calcium carbonate compound).)

[0013] In one embodiment, the silicon atom content is preferably 5000 ppm or less. The inventors have found that silicon atoms are an inhibitor of acicular formation, etc. By setting the silicon atom content within a specific range, the shape controllability of the calcium carbonate compound is improved, and a high aspect ratio can be efficiently achieved.

[0014] In one embodiment, the total content of phosphorus atoms, silicon atoms, and sulfur atoms is preferably 1,000 ppm to 18,000 ppm. By setting the total content of the three atoms involved in shape control of the calcium carbonate compound within this range, further improvement in shape controllability can be achieved.

[0015] In one embodiment, the calcium carbonate compound has an average particle size of 1.1 μm or more and 12.5 μm or less as measured by a laser diffraction method, from the viewpoint of suppressing shrinkage of the heating surface. In one embodiment, the calcium carbonate compound has an average major axis of 0.5 μm or more and 25 μm or less as measured by a scanning electron microscope. In another embodiment, the calcium carbonate compound has a BET specific surface area of ​​1 m or more. ２ / g or more 10m ２ By adjusting the shape control factors in the calcium carbonate compound, these properties can be satisfied alone or in combination.

[0016] 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.

[0017] In one embodiment, the calcium carbonate compound has a high aspect ratio and is therefore suitable as a high-performance additive for inorganic molded bodies.

[0018] In another embodiment, the present invention relates to an inorganic molded body containing the calcium carbonate compound.

[0019] By applying a calcium carbonate compound with a high aspect ratio to an inorganic molded body, it is possible to improve the strength and fire resistance, thereby achieving high functionality of the inorganic molded body.

[0020] FIG. 1 is a SEM photograph of a calcium carbonate compound of Example 1-1 of the present invention. FIG. 2 is a SEM photograph of a calcium carbonate compound of Example 1-2 of the present invention. FIG. 3 is a SEM photograph of a calcium carbonate compound of Example 1-3 of the present invention. FIG. 4 is a SEM photograph of a calcium carbonate compound of Example 1-4 of the present invention. FIG. 5 is a SEM photograph of a calcium carbonate compound of Comparative Example 1-1 of the present invention. FIG. 6 is a partial perspective view schematically showing a heating tester.

[0021] The calcium carbonate compound and inorganic molded body according to one embodiment of the present invention will be described below, but the present invention is not limited to these embodiments.

[0022] <Calcium-Based Carbonate Compound> In the calcium-based carbonate compound, the phosphorus atom content is 1,000 ppm or more and 15,000 ppm or less. The phosphorus atom content is preferably 1,200 ppm or more and 12,000 ppm or less, more preferably 1,500 ppm or more and 10,000 ppm or less, even more preferably 2,000 ppm or more and 8,000 ppm or less, and particularly preferably 2,500 ppm or more and 6,000 ppm or less. By setting the phosphorus atom content to the predetermined amount, it is possible to promote the formation of needle-like shapes in the calcium-based carbonate compound and to suppress rapid crystal growth, thereby reducing surface irregularities and porosity in the calcium-based carbonate compound.

[0023] In the calcium carbonate compound, the sulfur atom content is 2000 ppm or less. The sulfur atom content is preferably 1500 ppm or less, more preferably 1000 ppm or less, even more preferably 800 ppm or less, and particularly preferably 500 ppm or less. Note that, although the lower the sulfur atom content, the more preferable it is, the more preferable it may be contained at about 10 ppm. By setting the sulfur atom content to the predetermined amount, it is possible to suppress the inhibitory effect of acicular formation and the like, and it is possible to obtain a calcium carbonate compound having the desired high aspect ratio.

[0024] Sulfur atom content C Ｓ Phosphorus atom content C (ppm) Ｐ (ppm) to Ｓ / C Ｐ ) is preferably 0.30 or less, more preferably 0.25 or less, even more preferably 0.20 or less, and particularly preferably 0.18 or less. Ｓ / C Ｐ Although the smaller the aspect ratio, the more preferable, it may be 0.01 or more. By reducing the amount of sulfur atoms present, which act as an inhibitor of needle-like formation, etc., a calcium carbonate compound having a desired high aspect ratio can be efficiently obtained.

[0025] In calcium carbonate compounds, the content of silicon atoms is preferably 5000 ppm or less, more preferably 4000 ppm or less, even more preferably 3000 ppm or less, and particularly preferably 2000 ppm or less. Although the lower the content of silicon atoms, the more preferable it is, the more preferable it may be contained at about 5 ppm. By reducing the amount of silicon atoms present, which are an inhibitor of acicular formation, etc., calcium carbonate compounds having the desired high aspect ratio can be efficiently obtained.

[0026] In the calcium carbonate compound, the total content of phosphorus atoms, silicon atoms, and sulfur atoms is preferably 1,000 ppm or more and 18,000 ppm or less, more preferably 1,500 ppm or more and 16,000 ppm or less, even more preferably 2,000 ppm or more and 14,000 ppm or less, and particularly preferably 2,500 ppm or more and 12,000 ppm or less. By setting the total content of the three atoms involved in shape control of the calcium carbonate compound within the above range, further improvement in shape controllability can be achieved.

[0027] The aspect ratio of the average major axis to the average minor axis of the calcium carbonate compound is 6 to 19, preferably 6.5 to 17, and more preferably 7 to 15. Since the contents of phosphorus atoms and sulfur atoms in the calcium carbonate compound are within specific ranges, the shape can be highly controlled and the calcium carbonate compound can have a high aspect ratio within the range. Furthermore, when the calcium carbonate compound is used in an inorganic molded body, the calcium carbonate compound with a high aspect ratio effectively functions as a reinforcing material, thereby improving the strength and fire resistance of the inorganic molded body.

[0028] The crystal structure of the calcium carbonate compound may be a calcite type, an aragonite type, or a combination thereof. In order to provide the calcium carbonate compound with the above aspect ratio, it is preferable that the calcium carbonate compound contains at least an aragonite type crystal structure.

[0029] 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, which can suitably impart a high aspect ratio to the calcium carbonate compound and also improve the dispersibility of the calcium carbonate compound.

[0030] 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 makes it possible to suitably impart a high aspect ratio to the calcium carbonate compound and to suppress aggregation of the calcium carbonate compound with other components or aggregation of the calcium carbonate compound with other components.

[0031] 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 suitably impart a high aspect ratio to the calcium carbonate compound and improve the dispersibility of the calcium carbonate compound.

[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 based on the carbon dioxide gas method can also be used to impart a predetermined aspect ratio to a calcium carbonate compound. 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 acicular 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 acicular aragonite-type calcium carbonate compound to a slaked lime slurry and carrying out a carbonation reaction while stirring at high stirring power, a method for producing an aragonite-type calcium carbonate compound by adding a phosphate compound, a method for producing an aragonite-type calcium carbonate compound using a slaked lime slurry prepared with an alkaline aqueous solution, and a method for producing an aragonite-type calcium carbonate compound using a slaked lime slurry prepared with water containing magnesium ions. By using one or a combination of two or more of these methods, calcium carbonate compounds 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 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 crystallization method, the amount of phosphate to be added is preferably 1 part by mass to 25 parts by mass, more preferably 4 parts by mass to 18 parts by mass, and even more preferably 6 parts by mass to 12 parts by mass, per 100 parts by mass of slaked lime (calculated as CaO). By adjusting the amount to such a range, the content of phosphorus atoms in the resulting calcium carbonate compound can be within a predetermined range.

[0040] The method for adjusting the content of sulfur atoms in the calcium carbonate compound to fall within the above range is not particularly limited. For example, a sulfate compound is sometimes added to control the aspect ratio so that it does not become too large (for example, so that it does not exceed 20). However, examples of the method include a method in which the amount of sulfate compound added is reduced or no sulfate compound is added in order to control the aspect ratio to a predetermined value, and a method in which sulfate compounds in the raw material for slaked lime are dissolved and removed with a strong alkali.

[0041] The method for adjusting the silicon atom content in a calcium carbonate compound to fall within the above range is not particularly limited. For example, silica compounds are sometimes added to prevent the aspect ratio from becoming too large (e.g., not exceeding 20). Examples of suitable methods include reducing the amount of silica compound added or not adding any silica compound at all to control the aspect ratio to a predetermined value, and appropriately selecting the type of fuel used to calcinate limestone to adjust the amount of fuel-derived impurities that may be contained in the slaked lime. For example, using heavy oil as the calcination fuel increases the amount of sulfuric acid-derived impurities (sulfur atoms), while using coal as the fuel increases the amount of coal ash-derived impurities (silicon atoms). Methods for reducing the content of sulfur and silicon atoms derived from impurities include burning liquefied natural gas (LNG) or hydrogen, and using an electric furnace.

[0042] 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.

[0043] In addition to the carbon dioxide gas method, a waste seawater utilization method in which an alkaline agent such as magnesium hydroxide is added to waste seawater (the residue after removing magnesium) generated when magnesium hydroxide is produced by adding slaked lime or the like to seawater is also preferred from the viewpoint of waste utilization and carbon dioxide reduction, and carbon dioxide gas is then blown into the waste seawater. Furthermore, as described above, in the process of producing magnesium hydroxide from seawater, calcium-based carbonate compounds by-produced in the step of removing carbonates from seawater and seawater residue mainly composed of magnesium hydroxide can also be used as the calcium-based carbonate compound source.

[0044] <Uses of calcium-based carbonate compounds> The uses of calcium-based carbonate compounds are not particularly limited. For example, they are suitable as high-performance additives for inorganic molded bodies, such as building materials, and fillers for resins. Hereinafter, embodiments in which calcium-based carbonate compounds are used in inorganic molded bodies will be described.

[0045] <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.

[0046] (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.

[0047] 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.

[0048] (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), wollastonite, lightweight aggregates (e.g., fly ash balloons, perlite, shirasu balloons, glass foams, etc.), and other SiO ２ 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.

[0049] 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 / cm３ 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.

[0050] (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.

[0051] 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.

[0052] (Calcium-Based Carbonate Compound) As the calcium-based carbonate compound, the calcium-based carbonate compounds described above can be suitably used.

[0053] 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 the low thermal conductive calcium carbonate compound in a content within the above range, the strength and fire resistance of the inorganic molded body can be improved.

[0054] (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.

[0055] The bulk density of the inorganic molded body is 0.7 g / mL or more and 1.4 g / cm ３ Preferably, the concentration is 0.8 g / mL or more and 1.2 g / cm ３ More preferably, it is 0.9 g / mL or more and 1.1 g / cm ３ It is even more preferable that:

[0056] (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.

[0057] (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.

[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 5.

[0060] (1) Phosphorus, Sulfur, and Silicon Atom Contents <ICP-AES Method> 0.2 g of calcium carbonate compound was weighed as a sample, moistened with water, and 10 mL of hydrochloric acid (a 1:1 volumetric mixture of concentrated hydrochloric acid and water) was added using a dispenser. The mixture was then heated and dissolved. After cooling, the mixture was transferred to a 250 mL volumetric flask and diluted to 250 mL with water. 20 mL of this solution was then transferred to a 50 mL volumetric flask, and water was added to 50 mL to prepare the sample solution for measurement. Separately, 20 mL of the aqueous solution diluted to 250 mL was transferred to a 50 mL volumetric flask, and standard solutions of each element (phosphorus, sulfur, and silicon) were added as desired to prepare standard solutions for calibration curves with different concentrations. 1000 ppm atomic absorption standard solutions (commercially available) were used as the standard solutions for each element.

[0061] The calibration standard solutions containing different concentrations of each element added and the sample solution for measurement were placed in the autosampler of an inductively coupled plasma atomic emission spectrometry (ICP-AES) instrument (Hitachi High-Tech Science Corporation, "SPECTROBLUE FMS36 Model"), and the amounts (ppm) of phosphorus atoms, sulfur atoms, and silicon atoms were measured under the following conditions. <Measurement conditions> High-frequency output: 1.4 kW Carrier gas (humidified) flow rate: 0.9 L / min Plasma gas flow rate: 13.0 L / min Auxiliary gas flow rate: 1.0 L / min Liquid type: Aqueous solution Number of integrations: 3 Sample order: For each sample Measurement method: Standard addition method Calibration curve weighting: None Measurement wavelengths: Phosphorus atom 177.495 nm, sulfur atom 182.034 nm, silicon atom 251.612 nm

[0062] (2) Sulfur atom content C Ｓ Phosphorus atom content C (ppm) Ｐ (ppm) to Ｓ / C Ｐ The content C of sulfur atoms obtained in (1) above Ｓ (ppm) and phosphorus atom content C Ｐ (ppm) to ratio (C Ｓ / C Ｐ ) was calculated.

[0063] (3) 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.

[0064] (4) 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).

[0065] (5) 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 5 show SEM images of the examples and comparative examples. Using image analysis software (Image J), ​​20 particles were randomly selected from the obtained SEM images, and the average values ​​of the long diameter, short diameter (the diameter across an axis perpendicular to the long diameter axis at the center of the long diameter axis), and aspect ratio (the ratio of the long diameter to the short diameter) of the primary particles were calculated.

[0066] <Production of Calcium-Based Carbonate Compound> [Example 1-1] Calcium-Based Carbonate Compound (Aspect Ratio 6.6) 7,000 g of quicklime powder produced by the co-firing of limestone and coal was added to 50 L of water at 70°C with stirring and slaked for 1 hour to prepare milk of lime. This milk of lime (6,980 g in terms of CaO), 630 g of aragonite seed crystal powder, and 500 g of disodium hydrogen phosphate dodecahydrate were prepared and each was added to a 220 L SUS vessel with a baffle and pre-filled with 180 L of water with stirring to prepare a mixed slurry of 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 an LNG-fueled steam production boiler, and a test blower was used to draw in the exhaust gas. CO 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.

[0067] Example 1-2 Calcium-Based Carbonate Compound (Aspect Ratio 8.6) A sample powder of a calcium-based carbonate compound was obtained by the same procedure as in Example 1-1, except that 6,980 g (calculated as CaO) of commercially available slaked lime powder (Yoshimi Lime Industry Co., Ltd., Best Industrial Slaked Lime), 630 g of aragonite seed crystal powder, and 1,500 g of disodium hydrogen phosphate dodecahydrate were added.

[0068] Example 1-3 Calcium-Based Carbonate Compound (Aspect Ratio 10.4) A sample powder of a calcium-based carbonate compound was obtained by the same procedure as in Example 1-1, except that 6,980 g (calculated as CaO) of commercially available slaked lime powder (Yoshimi Lime Industry Co., Ltd., Best Industrial Slaked Lime), 630 g of aragonite seed crystal powder, and 500 g of disodium hydrogen phosphate dodecahydrate were added.

[0069] Example 1-4 Calcium-Based Carbonate Compound (Aspect Ratio 18.2) 7,000 g of commercially available quicklime (granular best quality quicklime, manufactured by Yoshimi Lime Industry Co., Ltd.) was added to 50 L of 70°C water with stirring and slaked for 1 hour to prepare milk of lime. A sample powder of calcium-based carbonate compound was obtained in the same manner as in Example 1-1, except that the milk of lime was 3,400 g in terms of CaO, 310 g of the sample powder of calcium-based carbonate compound obtained in Example 1-3 was used as aragonite seed crystals, and 240 g of disodium hydrogen phosphate dodecahydrate was used.

[0070] Comparative Example 1-1 Calcium-Based Carbonate Compound (Aspect Ratio 5.2) A sample powder of a calcium-based carbonate compound was obtained by the same procedure as in Example 1-1, except that 6,980 g (calculated as CaO) of commercially available slaked lime powder (Yoshimi Lime Industry Co., Ltd., Best Industrial Slaked Lime), 630 g of aragonite seed crystal powder, and 500 g of disodium hydrogen phosphate dodecahydrate were added, and then 125 g of sodium sulfate was further added.

[0071] Comparative Example 1-2 Calcium-Based Carbonate Compound (Aspect Ratio 5.3) A sample powder of a calcium-based carbonate compound was obtained by the same procedure as in Example 1-1, except that 6,980 g, in terms of CaO, of commercially available slaked lime powder (Yoshimi Lime Industry Co., Ltd., Best Industrial Slaked Lime), 630 g of aragonite seed crystal powder, and 3,000 g of disodium hydrogen phosphate dodecahydrate were added.

[0072]

[0073] <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.

[0074] [Example 2-1] 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.

[0075] Example 2-2 Production of inorganic molded body by papermaking method An inorganic molded body was obtained in the same manner as in Example 2-1, except that the calcium carbonate compound of Example 1-2 was used as the calcium carbonate compound.

[0076] Example 2-3 Production of Inorganic Molded Body by Papermaking Method An inorganic molded body was obtained in the same manner as in Example 2-1, except that the calcium carbonate compound of Example 1-3 was used as the calcium carbonate compound.

[0077] Example 2-4 Production of Inorganic Molded Body by Papermaking Method An inorganic molded body was obtained in the same manner as in Example 2-1, except that the calcium carbonate compound of Example 1-4 was used as the calcium carbonate compound.

[0078] Comparative Example 2-1 Production of Inorganic Molded Body by Papermaking Method An inorganic molded body was obtained in the same manner as in Example 2-1, except that the calcium carbonate compound of Comparative Example 1-1 was used as the calcium carbonate compound.

[0079] Comparative Example 2-2 Production of Inorganic Molded Body by Papermaking Method An inorganic molded body was obtained in the same manner as in Example 2-1, except that the calcium carbonate compound of Comparative Example 1-2 was used as the calcium carbonate compound.

[0080] [Comparative Example 2-3] Production of inorganic molded body by papermaking method An inorganic molded body was obtained in the same manner as in 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.

[0081] <Evaluation of Inorganic Molded Articles> The inorganic molded articles produced by papermaking in the Examples and Comparative Examples were evaluated as follows. The results are shown in Table 2.

[0082] (Bulk Density) The bulk density was measured in accordance with JIS A 5430.

[0083] (Heating Test) The heating test was performed using the following equipment and procedure. FIG. 6 is a partial perspective view showing a schematic diagram of a heating tester. As shown in FIG. 6, an electric heater was used as a heat source, and a fireproof material was installed between the test specimen and the heat source so that the temperature could be stabilized at around 900°C, and the temperature of the back surface of the test specimen could be measured with a thermocouple. Specifically, an electric heater (1.2 kW heater) was fixed as the heat source equipment so that the distance between the heating surface of the test specimen and the heat source was approximately 70 mm.

[0084] 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 -S０ | / 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.)

[0085]

[0086] The inorganic molded bodies of the Examples were superior to the Comparative Examples in both shrinkage on the heated surface and temperature rise on the reverse surface, demonstrating good fire resistance. Furthermore, the inorganic molded bodies of the Examples did not develop cracks after heating (not shown).

[0087] [Example 3-1] Production of inorganic molded body by extrusion molding method The materials shown in Table 3 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] Example 3-2 Production of Inorganic Molded Body by Extrusion Molding Method An inorganic molded body was obtained in the same manner as in Example 3-1, except that the calcium carbonate compound of Example 1-2 was used as the calcium carbonate compound.

[0089] Example 3-3 Production of inorganic molded body by extrusion molding method An inorganic molded body was obtained in the same manner as in Example 3-1, except that the calcium carbonate compound of Example 1-3 was used as the calcium carbonate compound.

[0090] Example 3-4 Production of Inorganic Molded Body by Extrusion Molding Method An inorganic molded body was obtained in the same manner as in Example 3-1, except that the calcium carbonate compound of Example 1-4 was used as the calcium carbonate compound.

[0091] Comparative Example 3-1 Production of Inorganic Molded Body by Extrusion Molding Method An inorganic molded body was obtained in the same manner as in Example 3-1, except that the calcium carbonate compound of Comparative Example 1-1 was used as the calcium carbonate compound.

[0092] Comparative Example 3-2 Production of Inorganic Molded Body by Extrusion Molding Method An inorganic molded body was obtained in the same manner as in Example 3-1, except that the calcium carbonate compound of Comparative Example 1-2 was used as the calcium carbonate compound.

[0093] [Comparative Example 3-3] Production of inorganic molded body by extrusion molding method An inorganic molded body was obtained in the same manner as in Example 3-1, 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.

[0094] <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 3.

[0095] (Bulk Density) The bulk density was measured in accordance with JIS A 5430.

[0096] (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 )

[0097] (Heating test) Measurements were made in the same manner as in the papermaking method. In addition, after the completion of the test (5) above, the test specimen was removed and the following items were measured (each item was also measured before 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.

[0098]

[0099] The inorganic molded bodies of the Examples exhibited good strength and fire resistance, with strength, heated surface shrinkage, back surface temperature rise, and post-heat warpage all being equal to or greater than those of the Comparative Examples. Furthermore, the inorganic molded bodies of the Examples did not develop cracks after heating (not shown).

Claims

1. A calcium carbonate compound having a phosphorus atom content of 1,000 ppm or more and 15,000 ppm or less, a sulfur atom content of 2,000 ppm or less, and an aspect ratio of the average major axis to the average minor axis of 6 or more and 19 or less.

2. A calcium carbonate compound according to claim 1, having a silicon atom content of 5,000 ppm or less.

3. A calcium carbonate compound according to claim 2, having a total content of phosphorus atoms, silicon atoms and sulfur atoms of 1,000 ppm or more and 18,000 ppm or less.

4. The content C of the sulfur atoms Ｓ The content C of the phosphorus atoms (ppm) Ｐ (ppm) (C Ｓ / C Ｐ 2. The calcium carbonate compound according to claim 1, wherein the calcium carbonate content is 0.30 or less.

5. The calcium carbonate compound according to claim 1, having an average particle size measured by laser diffraction method of 1.1 μm or more and 12.5 μm or less.

6. A calcium carbonate compound according to claim 1, having an average long diameter of 0.5 μm or more and 25 μm or less as measured by scanning electron microscope observation.

7. BET specific surface area is 1 m ２ / g or more 10m ２ The calcium carbonate compound according to claim 1, wherein the calcium carbonate content is 1 / g or less.

8. The calcium carbonate compound according to claim 1, wherein the calcium carbonate compound is a synthetic calcium carbonate compound.

9. A calcium carbonate compound according to any one of claims 1 to 8, which is for use in an inorganic molded body.

10. An inorganic molding comprising the calcium carbonate compound according to any one of claims 1 to 8.

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