Calcium-based carbonate compound and inorganic molded body

Abstract

To provide a calcium-based carbonate compound which, when used for an inorganic molded body that serves as a building material, enables the fluidity of a mixture thereof to be maintained during the production process, while improving the strength of the inorganic molded body; and also to provide an inorganic molded body.SOLUTION: Provided is a cubic calcium-based carbonate compound for an inorganic molded body. The average particle diameter of the calcium-based carbonate compound is preferably 2 μm to 25 μm inclusive as measured by a laser diffraction method. The BET specific surface area of the calcium-based carbonate compound is preferably 0.3 m2 / g to 3 m2 / g inclusive.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to calcium-based carbonate compounds and inorganic molded bodies.

Background Art

[0002] An inorganic molded body is a molded body mainly composed of inorganic substances such as hydraulic materials and siliceous materials, and has characteristics such as fire resistance, light weight, high strength, and workability. Therefore, it is widely used as an exterior wall material, a roof base material, an eaves ceiling material, etc. for houses. It is also widely used for the foundation parts, walls, columns, floors, etc. of buildings where strength and fire resistance are required.

[0003] As a technique for increasing the strength, which is one of the important performances required for an inorganic molded body, a technique of blending acicular calcium carbonate has been proposed (Japanese Patent No. 6898926).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the strength of the inorganic molded body obtained by the above technique may decrease, and the fluidity of the raw material mixture in the manufacturing process may decrease, and as a result, the working efficiency of the entire manufacturing process may decrease.

[0006] An object of the present invention is to provide a calcium-based carbonate compound and an inorganic molded body that can improve the strength of the inorganic molded body while maintaining the fluidity of the mixture in the manufacturing process when used for an inorganic molded body as a building material.

Means for Solving the Problems

[0007] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by the following configuration, and have completed the present invention.

[0008] In one embodiment, the present invention comprises: The present invention relates to a cubic calcium carbonate compound for use in inorganic moldings.

[0009] In the field of inorganic moldings, it is widely known that needle-shaped or fibrous reinforcing materials such as needle-shaped calcium carbonate are used to increase the strength of inorganic moldings. However, if the amount of needle-shaped reinforcing material is increased to further improve the strength, the fluidity of the mixture decreases as described above, so that there is a trade-off between improving the strength and maintaining the fluidity. After repeated studies, the present inventors unexpectedly found that a cubic calcium carbonate compound can improve the strength of the resulting inorganic molding while maintaining the fluidity of the mixture during the manufacturing process. The present invention was completed by developing such novel findings. From the above, the calcium carbonate compound is suitable for use in inorganic moldings.

[0010] Although the reason why the calcium carbonate compound can achieve both fluidity and strength is unclear, it is presumed as follows. Since the calcium carbonate compound is cubic, the shear stress in the mixture is reduced, and the viscosity-increasing effect is smaller than that of needle-shaped objects. As a result, the fluidity of the mixture can be maintained. In addition, the strength and density of the calcium carbonate compound itself are improved due to its cubic shape, and the strength of the inorganic molded body can be improved by homogeneous dispersion or homogeneous filling due to isotropy (non-orientation) in the mixture. Furthermore, the viscosity of the mixture containing the needle-shaped objects is high, making it difficult for bubbles in the mixture to escape. If the final product is obtained with bubbles remaining, the strength of the final product may decrease. With a cubic calcium carbonate compound, the air bubbles in the mixture are easily released due to the above-mentioned fluidity and isotropy, so it is presumed that this point also makes it possible to prevent or improve the decrease in strength.

[0011] In this specification, the term "cubic shape" does not refer only to a regular cubic shape, but refers to a shape that can be regarded as approximately cubic. For example, even if one or more of the vertices of the cube are rounded or chipped, if the cube can be restored by complementing that part, it is in a cubic shape. Also, if the length of one side of the target shape is within the range of 50% or more and 150% or less of the length of the other side, the target shape is in a cubic shape. Furthermore, the shape of one surface of the target shape is not limited to a square, and as long as the ratio of the lengths of the two sides is satisfied, it may be any shape such as a trapezoid, a rhombus, or a quadrilateral with four different side lengths. In addition, it is not necessary for all the particles constituting the calcium-based carbonate compound to be in a cubic shape. When the ratio of the particles in a cubic shape among all the particles is the largest, the calcium-based carbonate compound is in a cubic shape.

[0012] In this specification, the term "calcium-based carbonate compound" is a compound mainly composed of calcium carbonate, and is a concept that allows the inclusion or coexistence of other sub-components that can be incorporated in the manufacturing process or the like. The content of calcium carbonate in the calcium-based carbonate compound is preferably 80% by mass or more. As a method for measuring the content ratio of calcium carbonate in the calcium-based carbonate compound, the disodium ethylenediaminetetraacetate titration method can be preferably employed.

[0013] <Disodium Ethylenediaminetetraacetate Titration Method> Weigh 1 g of the calcium-based carbonate compound (dried at 105 °C for 2 hours) as a sample, suspend it in 50 mL of water, add 10 mL of hydrochloric acid (a solution prepared by mixing concentrated hydrochloric acid and water at a volume ratio of 1:1), and heat and dissolve it. After cooling, transfer it to a 250 mL volumetric flask, add water up to the same volume to make it up to the mark. From this, 5.00 mL is taken, and water is added so that the total volume of the solution is about 50 mL. Add 5 mL of a buffer solution (a solution prepared by dissolving 500 g of potassium hydroxide in water to make 1,000 mL), and further add a commercially available dithizone NN dilution powder, and titrate with a titration reagent (a solution prepared by dissolving about 3.8 g of disodium ethylenediaminetetraacetate in water to make 1,000 mL). The titration is terminated when the color of the solution changes from red to blue. The content (%) of calcium carbonate is calculated by the following formula.

[0014] [Number] (In the formula, f is the factor of the titrant. The factor is determined by standardizing with the BT indicator using the titrant. V is the consumption volume (mL) of the titrant. W is the sampling amount of the sample (0.02 g of calcium-based carbonate compound).)

[0015] In one embodiment, it is preferable that the average particle diameter of the calcium-based carbonate compound by the laser diffraction method is 2 μm or more and 25 μm or less. In one embodiment, the BET specific surface area of the calcium-based carbonate compound is 0.3 m 2 / g or more and 3 m 2 / g or less. Further, in one embodiment, it is preferable that the apparent specific gravity of the calcium-based carbonate compound is 1 g / mL or more and 2 g / mL or less. By satisfying these characteristics alone or in combination, it is possible to achieve a higher level of both fluidity and strength.

[0016] In one embodiment, according to the calcium-based carbonate compound, the P funnel flow-down time can be 7 seconds or more and 10 seconds or less. Thereby, the calcium-based carbonate compound can exhibit good fluidity.

[0017] In one embodiment, the magnesium content in the calcium-based carbonate compound may be 1000 ppm or more. The magnesium content in the calcium-based carbonate compound varies depending on raw materials, manufacturing methods, etc. For example, when using raw materials relatively rich in magnesium (such as seawater), the magnesium content in the calcium-based carbonate compound will be 1000 ppm or more. When using raw materials relatively low in magnesium (such as the supernatant of concrete sludge), the magnesium content in the calcium-based carbonate compound will be less than 1000 ppm.

[0018] In one embodiment, the calcium-based carbonate compound is preferably a synthetic calcium-based carbonate compound in terms of production efficiency and shape controllability.

[0019] In other embodiments of the present invention, The present invention relates to an inorganic molded body containing the calcium-based carbonate compound.

[0020] By applying the cubic calcium-based carbonate compound to the inorganic molded body, it is possible to efficiently obtain an inorganic molded body with high strength while maintaining fluidity during the manufacturing process and ensuring good workability.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0022] The calcium-based carbonate compound and the inorganic molded body according to one embodiment of the present invention will be described below. The present invention is not limited to these embodiments.

[0023] <Calcium-based carbonate compound> The calcium-based carbonate compound according to the present embodiment is cubic and is suitable for use in an inorganic molded body.

[0024] The average particle diameter of the calcium-based carbonate compound by the laser diffraction method is preferably 2 μm or more and 25 μm or less, more preferably 4 μm or more and 22 μm or less, and even more preferably 6 μm or more and 18 μm or less. Thereby, the fluidity of the mixture containing the calcium-based carbonate compound can be suitably maintained. In addition, the strength of the obtained inorganic molded body can be further improved.

[0025] The BET specific surface area of the calcium carbonate compound is preferably 0.3 m 2 / g or more and 3 m 2 / g or less, more preferably 0.4 m 2 / g or more and 2.6 m 2 / g or less, still more preferably 0.5 m 2 / g or more and 2.4 m 2 / g or less. Thereby, the fluidity of the mixture containing the calcium carbonate compound can be suitably maintained, and the dispersibility of the calcium carbonate compound can also be improved. In addition, the strength of the obtained inorganic molded body can be further improved.

[0026] The apparent specific gravity of the calcium carbonate compound is preferably 1.00 g / mL or more and 2.00 g / mL or less, more preferably 1.05 g / mL or more and 1.80 g / mL or less, still more preferably 1.10 g / mL or more and 1.60 g / mL or less. Thereby, the fluidity of the mixture containing the calcium carbonate compound can be suitably maintained. In addition, the density and strength of the calcium carbonate compound are increased, and the strength of the obtained inorganic molded body can be further improved.

[0027] The P-funnel flow-down time of the calcium carbonate compound is preferably 7 seconds or more and 10 seconds or less, more preferably 7.5 seconds or more and 9.8 seconds or less, still more preferably 8 seconds or more and 9.5 seconds or less. Since the calcium carbonate compound is cubic, excellent fluidity can be exhibited.

[0028] The content of magnesium in the calcium carbonate compound may be 1000 ppm or more, may be 5000 ppm or more, or may be 10000 ppm or more. The upper limit of the magnesium content is about 50000 ppm depending on the raw materials, manufacturing method, etc.

[0029] As the crystal structure of the calcium carbonate compound, a calcite type, an aragonite type, or a combination thereof can be preferably adopted. From the viewpoint of obtaining a cubic calcium carbonate compound, it is preferable that the calcite type crystal structure is relatively abundant and the aragonite type crystal structure is relatively scarce.

[0030] In the X-ray diffraction measurement of the calcium carbonate compound, the peak intensity I a of calcite to the peak intensity I c of aragonite, the ratio I a / I c is preferably 0.1 or less, more preferably 0.08 or less, and even more preferably 0.06 or less. Thereby, a cubic calcium carbonate compound can be efficiently obtained.

[0031] The calcium carbonate compound is preferably a synthetic calcium carbonate compound in terms of production efficiency and shape controllability.

[0032] (Method for producing calcium carbonate compound) The method for producing a calcium carbonate compound is not particularly limited, and a known production method can be adopted. Typically, a solution method for producing a calcium carbonate compound by performing salt exchange by bringing a carbonate (carbonate ion) into contact with calcium (calcium ion) such as seawater can be preferably adopted. Ca 2+ + CO3 2- → CaCO3(A)

[0033] As the salt of the carbonate ion used in the reaction formula (A), alkali metal salts (Li, Na, K), alkaline earth metal salts (Mg, Sr, excluding Ca) are used, and among them, alkali metal salts are preferably used. Among them, the Na salt (sodium carbonate) is preferable in terms of versatility and cost.

[0034] The contact between the carbonate and seawater or the like may be carried out by introducing an aqueous solution or slurry of the carbonate into the seawater or the like, or by introducing the seawater or the like into the aqueous solution or slurry. From the viewpoint of efficiently obtaining the target cubic calcium-based carbonate compound, it is preferable to introduce it all at once.

[0035] Seawater may be used as it is directly pumped from the nearby sea, or may be used after undergoing treatment such as filtration. The pumping is not limited to the offshore area, and can be carried out at any location as long as seawater can be obtained. Calcium-rich seawater generated when removing magnesium hydroxide from seawater may also be used.

[0036] The amount of carbonate added is not particularly limited as long as it is set so that the amount of carbonate ions required for the reaction with the amount of calcium ions in seawater or the like can be obtained according to the above reaction formula (A). Although an equimolar amount of calcium ions and carbonate ions is preferable, the amount of carbonate ions may be within the range of ±50 to 200% in molar ratio with respect to the amount of calcium ions.

[0037] The salt exchange reaction due to the contact between the carbonate and seawater or the like proceeds relatively rapidly. The reaction time may be set to such an extent that the salt exchange reaction proceeds sufficiently, and can be set to 1 second or more, preferably 1 minute or more and 60 minutes or less, and more preferably 5 minutes or more and 50 minutes or less.

[0038] The generated calcium-based carbonate compound may be filtered and dried to form a powder, or may be used as a calcium-based carbonate compound source in the form of a slurry or cake without undergoing filtration and drying.

[0039] <Inorganic molded body> The inorganic molded body is not particularly limited, and typically includes molded plates for building materials and concrete structures (concrete molded bodies), etc. Hereinafter, the applicable compositions and the like will be described in detail according to the use.

[0040] (Molded plate for building materials) The molded plate preferably contains a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium-based carbonate compound.

[0041] (Hydraulic material) Examples of the hydraulic material include cementitious materials, gypsum, lime, slag, etc. Examples of the cementitious materials include commonly used cements such as ordinary Portland cement, early strength cement, medium heat cement, fly ash cement, blast furnace slag cement, and alumina cement. Examples of the gypsum include anhydrite, hemihydrate gypsum, dihydrate gypsum, etc. Examples of the slag include blast furnace slag, converter slag, etc. These hydraulic materials can be used alone or in combination of two or more kinds.

[0042] 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 still more preferably 10% by mass or more and 40% by mass or less based on the total amount of the materials constituting the formed plate. By setting the content of the hydraulic material within the above range, physical properties such as the bending strength and peel strength of the formed plate can be improved, and the increase in the bulk specific gravity of the formed plate can be suppressed, thereby enhancing the workability during construction and the like.

[0043] (Siliceous material) Examples of the siliceous material include materials rich in SiO2 such as 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. These siliceous materials can be used alone or in combination of two or more kinds. Talc, mica, and wollastonite can also be used as the reinforcing fiber materials described later.

[0044] 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 still more preferably 15% by mass or more and 45% by mass or less, based on the total amount of the materials constituting the molded plate. If the content of the siliceous material is within the above range, it becomes possible to set the flexural strength, bulk density, water absorption rate, dimensional stability, etc. of the molded plate within the target range. Note that as the siliceous material, lightweight aggregates such as perlite, fly ash balloons, and shirasu balloons with a unit volume mass of 0.5 g / cm 3 When blending lightweight aggregates below, in order to prevent the bulk density from becoming too light and the strength such as flexural strength and peel strength from becoming weak, it is preferable to use other siliceous materials in combination so that the content of the lightweight aggregate is 20% by mass or less based on the total amount of the materials constituting the molded plate.

[0045] (Reinforcing fiber material) As the reinforcing fiber material, for example, pulp such as softwood pulp, hardwood pulp, fibrillated pulp of these, 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 can be used. These reinforcing fiber materials can be used alone or in combination of two or more.

[0046] For improving the strength and imparting toughness of the molded plate, 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 still more preferably 4% by mass or more and 22% by mass or less, based on the total amount of the materials constituting the molded plate. By setting the content of the reinforcing fiber material within the above range, it is possible to suppress the fibers from protruding on the surface of the molded plate and improve the smoothness while exerting a sufficient reinforcing effect. When an inorganic reinforcing fiber material with an average length of 1 mm to 50 mm is blended as the reinforcing fiber material, in order to improve the smoothness of the molded plate, it is preferable to use other reinforcing fiber materials in combination so that the content thereof is 10% by mass or less based on the total amount of the materials constituting the molded plate.

[0047] (Calcium-based carbonate compound) As the calcium-based carbonate compound, the above-mentioned calcium-based carbonate compound can be preferably adopted.

[0048] The content of the calcium-based 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 still more preferably 12% by mass or more and 50% by mass or less, based on the total amount of the materials constituting the formed plate. By blending the calcium-based carbonate compound with low thermal conductivity in the content within the above range, the strength and fire resistance of the formed plate can be improved.

[0049] (Optional component) In addition to the above materials, in order to impart various functions to the formed plate, materials such as resin hollow bodies, wood chips, wood powder, resin powder, defoaming agents, flocculants, water repellents, thickeners (such as methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.), and dispersants can be variously blended according to the purpose. It is also possible to appropriately add and use recycled materials obtained by pulverizing end materials generated during the processing of the formed plate.

[0050] The bulk density of the formed plate is preferably 0.7 g / cm 3 or more and 2.0 g / cm 3 or less, more preferably 0.8 g / cm 3 or more and 1.8 g / cm 3 or less, and still more preferably 0.9 g / cm 3 or more and 1.6 g / cm 3 or less.

[0051] (Manufacturing method of the formed plate) The manufacturing method of the formed plate according to this embodiment is not particularly limited, and generally used papermaking methods, extrusion molding methods, flow-on molding methods, casting molding methods, press (compression) molding, etc. can be used. The formed plate can be obtained by subjecting the green sheet formed by these methods to press dewatering or pattern processing such as embossing, and then curing at normal temperature, steam curing, autoclave curing, etc. Further, drying may be performed, and shape processing or painting may be performed as necessary.

[0052] (Use of the formed plate) The use of the formed plate is not particularly limited, and it can be suitably used as interior and exterior finishing materials such as wall building materials, floor materials, roof materials, various boards, exterior decoration members, and fixtures, and as performance maintenance materials such as sealing materials, heat insulation materials, sound absorption materials, and waterproof building materials. The formed plate is preferably a cement-based formed plate containing a cementitious material, and more preferably a calcium silicate formed body.

[0053] (Concrete building) The concrete building is composed of a hardened body of a hydraulic composition. The hydraulic composition is composed of a powder containing at least one of blast furnace slag, an expansive material, slaked lime, quicklime, fly ash, and Portland cement in addition to a calcium-based carbonate compound. As the calcium-based carbonate compound, the above-mentioned calcium-based carbonate compound can be preferably adopted.

[0054] In addition to the above-mentioned hydraulic composition, aggregates such as sand and gravel, chemicals such as chemical admixtures for concrete, and fiber materials made of metals and polymer materials may be blended to form a hydraulic composition mixture material.

[0055] The hardened body of the hydraulic composition is obtained by hardening a paste obtained by kneading water into the above-mentioned hydraulic composition. Also, the hardened body of the hydraulic composition mixture material is obtained by hardening a kneaded product (corresponding to fresh mortar or fresh concrete) obtained by kneading water into the above-mentioned hydraulic composition mixture material, and corresponds to mortar or concrete.

[0056] The ratio of the calcium-based carbonate compound in the powder (the ratio of the calcium-based carbonate compound to cement) is in the range of 1% to 60% by mass, preferably 3% to 50% by mass, and more preferably 5% to 40% by mass.

[0057] For blast furnace slag, it is desirable to use blast furnace slag fine powder used in JIS (Japanese Industrial Standards) R5211 "Blast Furnace Cement" or blast furnace slag fine powder conforming to JIS A6206 "Blast Furnace Slag for Concrete". Also, the blast furnace slag preferably has a specific surface area of 2000 - 10000 cm 2 / g, more preferably 3500 - 7000 cm 2 / g.

[0058] For the expansive agent, for example, an expansive agent defined in JIS A6202 "Expansive Agent for Concrete" may be used. It is desirable to add the expansive agent at a ratio of 2 - 9 mass% based on the entire hydraulic composition.

[0059] For slaked lime, for example, those defined in JIS R9001 "Industrial Lime" may be used. Also, since quicklime turns into slaked lime when it comes into contact with water, for example, quicklime defined in JIS R9001 "Industrial Lime" can be used instead of slaked lime. In this case, it is advisable to correct the amount of water required when quicklime changes to slaked lime. For fly ash, for example, those conforming to JIS A6201 "Fly Ash for Concrete" may be used.

[0060] For Portland cement, ordinary Portland cement is used, but in addition to this, other Portland cements such as early - strength Portland cement, super - early - strength Portland cement, medium - heat Portland cement, low - heat Portland cement, sulfate - resistant Portland cement, etc., defined in JIS R5210 "Portland Cement", and JIS R5214 "Eco - Cement" can also be used.

[0061] When the hydraulic composition contains Portland cement, the proportion of Portland cement in the powder other than calcium - based carbonate compounds is 70 mass% or less, preferably 30 mass% or less.

[0062] In addition, when using Portland cement and blast furnace slag or fly ash, for example, JIS R5211 "blast furnace cement" in which the components are pre-mixed, or, for example, JIS R5213 "fly ash cement" may be used alone or in combination.

[0063] Since the calcium carbonate compound having the above characteristics is used, the hydraulic composition and the hydraulic composition admixture exhibit good fluidity, and the concrete hardened body can exhibit excellent compressive strength.

[0064] The density of the concrete structure is preferably 0.7 g / cm 3 or more and 2.0 g / cm 3 or less, more preferably 0.8 g / cm 3 or more and 1.8 g / cm 3 or less, and even more preferably 0.9 g / cm 3 or more and 1.6 g / cm 3 or less.

Examples

[0065] Hereinafter, the present invention will be described in detail using examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The measurement and evaluation of physical properties and the like were performed as follows.

[0066] <Evaluation of Calcium Carbonate Compound> For the calcium carbonate compounds and the like obtained in each production example, the following analysis was performed. The analysis results are shown in Table 1 and FIGS. 1 and 2.

[0067] (1) BET specific surface area The sample powder pretreated at about 130 ° C. for about 30 minutes in a nitrogen gas atmosphere using an 8-tube preheating unit (manufactured by MOUNTECH) was measured for BET specific surface area (m 2 / g) by the nitrogen gas adsorption method using a Macsorb HM Model-1208 (manufactured by MOUNTECH) as a BET specific surface area measuring device.

[0068] (2) Average particle size by laser diffraction method 50 mL of ethanol was placed in a 100 mL beaker, and approximately 0.2 g of the sample powder was added to the 100 mL beaker described above. Ultrasonic treatment (UD-201 manufactured by Tomy Seiko Co., Ltd.) was performed for 3 minutes to prepare a dispersion. This dispersion was measured using a laser diffraction method - particle size distribution analyzer (Microtrac HRA Model 9320-X100 manufactured by Nikkiso Co., Ltd.) to obtain the D 50 value as the average particle size (μm).

[0069] (3) Apparent specific gravity The apparent specific gravity of the sample powder was measured in accordance with JIS K6220.

[0070] (4) Content of magnesium atoms (ICP-AES method) 0.2 g of the calcium-based carbonate compound as the sample was weighed, moistened with water, and 10 mL of hydrochloric acid (a solution prepared by mixing concentrated hydrochloric acid and water in a volume ratio of 1:1) was added using a pipette, followed by heating and dissolution. After cooling, it was transferred to a 250 mL volumetric flask, and water was added to make up to 250 mL. From this, 20 mL was aliquoted into a 50 mL volumetric flask, and water was added to make up to 50 mL to obtain the test solution for measurement. On the other hand, 20 mL was aliquoted from the 250 mL made-up aqueous solution described above into a 50 mL volumetric flask, and standard solutions of each element (magnesium atoms) were arbitrarily added to prepare calibration standard solutions with different concentrations. The standard solutions of each element used were 1000 ppm standard solutions for atomic absorption (commercially available).

[0071] The calibration standard solutions with different concentrations obtained by adding each element and the test solution for measurement were set in the autosampler of an inductively coupled plasma atomic emission spectrometry (ICP-AES) apparatus (manufactured by Hitachi High-Technologies Corporation, "SPECTROBLUE FMS36 type"), and the amount of magnesium atoms (ppm) was 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 property: Aqueous solution Number of integrations: 3 times Sample order: For each sample Measurement method: Standard addition method Calibration curve weighting: None Measurement wavelength: Magnesium atom 279.553 nm

[0072] (5) Calculation of the ratio of the peak intensity I of 46° (aragonite) to the peak intensity I of 29° (calcite) by XRD measurement a of the peak intensity I of 29° (calcite) c Calculation of the ratio After the sample powder was pressed and fixed with a spatula blade on a predetermined sample stage, measurement was performed using an XRD apparatus (MiniFlex600-C manufactured by Rigaku Corporation), and identification analysis as a crystalline substance was performed. At the 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 ratio of the peak intensity I of 46° (aragonite) to the peak intensity I of 29° (calcite) (I a of the peak intensity I of 29° (calcite) c to (I a / I c ) was determined.

[0073] (6) Scanning electron microscope observation Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied onto it by tracing with a spatula blade. After platinum evaporation, a photograph of the particle image of the sample powder was taken at 2000 times magnification using a scanning electron microscope (FE-SEM: S-4700 manufactured by Hitachi, Ltd.). SEM photographs of the examples and comparative examples are shown in FIGS. 1 to 2.

[0074] [Production of calcium-based carbonate compound [Example 1-1] Calcium-based carbonate compound (cubic shape) 8510 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.8%) was charged into a 220 L capacity SUS container with a baffle plate filled with 100 L of water under stirring to prepare a sodium carbonate aqueous solution. On the other hand, 1000 L of seawater (Ca2+ The content (0.25 g / dL) was placed in a polyethylene container with a capacity of 2000 L. While stirring, 100 L of the aforementioned aqueous sodium carbonate solution was added all at once, and then stirring was continued for about 30 minutes to cause a reaction. After that, it was filtered, washed with about 5 times the amount of water relative to the solid content, dried at 110 °C for 24 hours, pulverized, and a sample powder of the calcium-based carbonate compound was obtained.

[0075] [Example 1-2] Calcium-based carbonate compound (cubic shape) To 1000 L of seawater from which magnesium hydroxide had been removed, 12.7 kg of magnesium chloride hexahydrate was added while stirring, and then 100 L of the aforementioned aqueous sodium carbonate solution was added all at once. Except for this, the same operations as in Example 1-1 were performed to obtain a sample powder of the calcium-based carbonate compound.

[0076] [Example 1-3] Calcium-based carbonate compound (cubic shape) To 100 L of seawater from which magnesium hydroxide had been removed, 10 L of the aforementioned aqueous sodium carbonate solution was added all at once while stirring, and then stirring was continued for about 30 minutes. After this reaction solution was used as a seed, another 100 L of seawater from which magnesium hydroxide had been removed was added, 10 L of the aforementioned aqueous sodium carbonate solution was added all at once while stirring, and then stirring was continued for about 30 minutes. This series of operations was continued a total of 10 times. Except for these operations, the same operations as in Example 1-1 were performed to obtain a sample powder of the calcium-based carbonate compound.

[0077] [Comparative Example 1-1] Calcium-based carbonate compound (acicular shape) Commercially available slaked lime powder (manufactured by Yoshimi Lime Industry Co., Ltd., industrial grade best slaked lime), 69 in terms of CaO conversion 80 g of aragonite seed crystal powder, 630 g, and 3000 g of disodium hydrogen phosphate dodecahydrate were prepared, and each was put into a 220 L capacity SUS container with a baffle plate filled with 180 L of water in advance under stirring to prepare a mixed slurry of raw materials. Then, the temperature was raised to 70 °C, and at this temperature, it was stirred at a rotational speed of 150 rpm using a stirrer equipped with a single-stage turbine blade. An exhaust gas extraction pipe was connected to the exhaust outlet of a boiler for producing steam using LNG as fuel, and while drawing in the exhaust gas using a test blower, when measured with a CO2 concentration measuring instrument (XP-3140 manufactured by Shin Cosmos Electric Co., Ltd.), the CO2 concentration showed 10% by volume. The exhaust gas was introduced into the above-mentioned 220 L capacity SUS container at a speed of 100 L / min using a test blower and reacted for 7 hours. Then, it was filtered, washed with about 5 times the amount of water relative to the solid content, dried at 110 °C for 24 hours, pulverized, and a sample powder of a calcium-based carbonate compound was obtained.

[0078]

Table 1

[0079] <Evaluation> Using the obtained calcium-based carbonate compound, the measurement of the P funnel flow-down time, as well as the production and compressive strength test of a cement compact were carried out. The results are shown in Table 3.

[0080] (Preparation of cement milk 1) 2 kg of cement (manufactured by Tokuyama Corporation, "Ordinary Portland Cement (N)") was put into 1600 mL of water in about 20 seconds, and it was mixed with a stirrer (manufactured by Yamato Scientific Co., Ltd., "Lab Stirrer (LR500B)") for 3 minutes from the start of input. After stopping the stirring and allowing it to stand for 3 minutes, it was manually stirred 10 times with a stirring rod (manufactured by AS ONE Corporation, "Stirring rod (POM made) φ10 × 300 mm") to prepare cement milk 1.

[0081] (Preparation of cement milk 2 - 7) The calcium carbonate compounds of Example 1-1 and Comparative Example 1-1 in the types and amounts shown in Table 2-1 below were added to 1600 mL of water, and after manually stirring with the stirring rod for about 30 seconds, the mixture was stirred at 400 rpm using the stirrer to obtain a mixture. 2 kg of cement (manufactured by Tokuyama Corporation, "Ordinary Portland Cement (N)") was added to this mixture in about 20 seconds, and the mixture was mixed with the stirrer for 3 minutes from the start of addition. After stopping the stirring and allowing it to stand for 3 minutes, it was manually stirred 10 times with the stirring rod to prepare Cement Milks 2 to 7.

[0082]

Table 2-1

[0083] (Preparation of Cement Milks 8 to 10) Except for using the calcium carbonate compounds of Example 1-2 in the types and amounts shown in Table 2-2 below, the same operations as those for preparing Cement Milks 2 to 7 were performed to prepare Cement Milks 8 to 10.

[0084]

Table 2-2

[0085] (Preparation of Cement Milks 11 to 13) Except for using the calcium carbonate compounds of Example 1-3 in the types and amounts shown in Table 2-3 below, the same operations as those for preparing Cement Milks 2 to 7 were performed to prepare Cement Milks 11 to 13.

[0086]

Table 2-3

[0087] (P Funnel Flow Time Test Method) In accordance with the "Test Method for Fluidity of Injected Mortar for Prepacked Concrete (Method Using P-Funnel)" (JSCE-F521-1999), the P-funnel flow-down time was measured. With the outlet of the P-funnel held down with a finger, each of the prepared cement milks was poured up to the marked line of the P-funnel (1750 ml), and measurement was started simultaneously with releasing the finger using a stopwatch. The time until the cement milk was discharged from the P-funnel was measured.

[0088] <Manufacture of Cement Moldings> [Example 2-1] 400 mL of the prepared cement milk 1 was poured into a cylindrical polyethylene bag (diameter: approximately 50 mm × length: approximately 550 mm × thickness: approximately 0.05 mm) up to the marked line. After injecting air as much as possible and sealing it, it was suspended in a thermostat set at 22°C. It was left for 28 days while suspended in the thermostat to cure the contents, and a total of 3 cement moldings were manufactured. The obtained cement moldings were cylindrical, with a diameter of approximately 5 cm and a length of approximately 20 cm.

[0089] [Examples 2-2 to 2-9 and Comparative Examples 2-1 to 2-4] Cement moldings were manufactured in the same manner as in Example 2-1, except that the cement milks shown in Tables 3-1 to 3-3 below were used.

[0090] (Density) The density was measured in accordance with JIS A 5430:2008 (Apparent Density Test).

[0091] (Compressive Strength Test) The compressive strength of the obtained cement moldings was measured in accordance with JIS A 1108:2018 (Test Method for Compression of Concrete).

[0092]

Table 3-1

[0093]

Table 3-2

[0094]

Table 3-3

[0095] In the cement milk using the calcium-based carbonate compound of the example, even if the content of the calcium-based carbonate compound was increased, there was no significant increase in the P funnel flow time compared to Comparative Example 2-1 without the calcium-based carbonate compound, and it had good fluidity. On the other hand, in Comparative Examples 2-2 to 2-4, as the content of the calcium-based carbonate compound was increased, the fluidity decreased significantly.

[0096] Furthermore, in the cement molded body of the example, by blending the calcium-based carbonate compound, the compressive strength was improved compared to Comparative Example 2-1. On the other hand, in Comparative Examples 2-2 to 2-4, even when the calcium-based carbonate compound was blended, the compressive strength decreased compared to the blank Comparative Example 2-1. Although the reason for the decrease in the compressive strength in Comparative Examples 2-2 to 2-4 in terms of the blank ratio is not clear, it is presumed that the calcium-based carbonate compound is needle-shaped and the surface energy has increased, resulting in aggregation and a decrease in the reinforcing effect, or that the needle shape has increased the viscosity of the cement milk, making it difficult for air bubbles to escape, and the cement molded body was obtained with air bubbles remaining.

[0097] From the above, it was found that in the cement milk using the calcium-based carbonate compound of the example, even if the content of the calcium-based carbonate compound was increased, it showed fluidity comparable to that of the blank product and exhibited excellent compressive strength when made into a cement molded body.

Claims

1. A cubic calcium carbonate compound for use in an inorganic molded article.

2. The calcium carbonate compound according to claim 1, having an average particle diameter of 2 μm or more and 25 μm or less as measured by the laser diffraction method.

3. The BET specific surface area is 0.3 m ２ / g or more and 3 m ２ / g or less, the calcium carbonate compound according to claim 1.

4. The calcium carbonate compound according to claim 1, having an apparent specific gravity of 1 g / mL or more and 2 g / mL or less.

5. The calcium carbonate compound according to claim 1, having a P funnel flow-down time of 7 seconds or more and 10 seconds or less.

6. The calcium carbonate compound according to claim 1, having a magnesium content of 1000 ppm or more.

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

8. An inorganic molded article containing the calcium carbonate compound according to any one of claims 1 to 7.

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