Calcium carbonate compounds and inorganic moldings

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 a calcium carbonate compound and an inorganic molded body. [Background technology]

[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. They are also widely used for foundations, walls, pillars, floors, etc. of buildings that require strength and fire resistance.

[0003] As a technique for increasing strength, which is one of the important properties required for inorganic molded bodies, a technique for compounding needle-shaped calcium carbonate has been proposed (Japanese Patent No. 6898926). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6898926 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even with the above techniques, the strength of the inorganic molded body obtained may decrease, and the fluidity of the mixture of raw materials during the manufacturing process may decrease, which may ultimately reduce the working efficiency of the entire manufacturing process.

[0006] The present invention aims to provide a calcium carbonate compound and an inorganic molded body that, when used in an inorganic molded body as a building material, can improve the strength of the inorganic molded body while maintaining the fluidity of the mixture during the manufacturing process. [Means for solving the problem]

[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 provides This invention relates to a cubic calcium carbonate compound for use in inorganic moldings.

[0009] In the field of inorganic moldings, it is widely known to use needle-shaped or fibrous reinforcing materials such as needle-shaped calcium carbonate to increase the strength of inorganic moldings. However, increasing the amount of needle-shaped reinforcing material to further improve strength results in a decrease in the fluidity of the mixture, as mentioned above, so there is a trade-off between improving strength and maintaining fluidity. After extensive research, the inventors unexpectedly discovered 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 expanding on this novel finding. For these reasons, 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 speculated as follows. Because 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 particles. As a result, the fluidity of the mixture can be maintained. Furthermore, the cubic shape improves the strength and density of the calcium carbonate compound itself, and its isotropy (non-orientation) in the mixture allows for homogeneous dispersion or homogeneous packing, thereby improving the strength of the inorganic molded product. Furthermore, the viscosity of a mixture containing needle-shaped particles is high, making it difficult for air bubbles to escape. If the final product is obtained with air bubbles remaining, the strength of the final product may be reduced. The cubic calcium carbonate compound facilitates the escape of air bubbles in the mixture due to its fluidity and isotropy, as described above, and this is also speculated to prevent or improve strength reduction.

[0011] As used herein, the term "cubic" does not refer to a regular cubic shape, but rather refers to a shape that can be roughly considered a cube. For example, even if one or more vertices of a cube are rounded or missing, the cube is still cubic if the cube can be restored by filling in the missing vertices. Furthermore, the target shape is cubic if the length of one side of the target shape is between 50% and 150% of the length of the other side. Furthermore, the shape of one side of the target shape is not limited to a square, and may be any shape, such as a trapezoid, rhombus, or rectangle with four sides of different lengths, as long as the ratio of the lengths of the two sides is satisfied. In addition, not all particles constituting the calcium carbonate compound need be cubic; the calcium carbonate compound is cubic if the proportion of cubic particles among all particles is the largest.

[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 80% 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.

[0013] <Disodium ethylenediaminetetraacetic acid titration method> Weigh out 1 g of calcium carbonate sample (dried at 105°C for 2 hours) and suspend it in 50 mL of water. Add 10 mL of hydrochloric acid (a 1:1 mixture of concentrated hydrochloric acid and water by volume) and heat to dissolve. After cooling, transfer to a 250 mL volumetric flask and add water to the same volume. Take 5.00 mL of this and add water to bring the total volume to approximately 50 mL. Add 5 mL of buffer solution (a 1,000 mL solution of 500 g of potassium hydroxide dissolved in water), then add commercially available Dotite NN diluted powder. Titrate with titration reagent (a 1,000 mL solution of approximately 3.8 g of disodium ethylenediaminetetraacetate dissolved in water). The titration is completed when the color of the solution changes from red to blue. Calculate the calcium carbonate content (%) using the following formula:

[0014]

number

[0015] In one embodiment, the calcium carbonate compound has an average particle size of 2 μm or more and 25 μm or less, as measured by a laser diffraction method. In one embodiment, the calcium carbonate compound has a BET specific surface area of ​​0.3 m 2 / g or more 3m 2 / g or less. In one embodiment, the apparent specific gravity of the calcium carbonate compound is preferably 1 g / mL or more and 2 g / mL or less. By satisfying these properties alone or in combination, it is possible to achieve a higher level of both fluidity and strength.

[0016] In one embodiment, the calcium carbonate compound can have a flow time through a P funnel of 7 seconds or more and 10 seconds or less, thereby enabling the calcium carbonate compound to exhibit good fluidity.

[0017] In one embodiment, the magnesium content of the calcium carbonate compound may be 1000 ppm or more. The magnesium content of the calcium carbonate compound varies depending on the raw material, manufacturing method, etc. For example, if a raw material relatively rich in magnesium (such as seawater) is used, the magnesium content of the calcium carbonate compound will be 1000 ppm or more. If a raw material relatively low in magnesium (such as the supernatant liquid of concrete sludge) is used, the magnesium content of the calcium carbonate compound will be less than 1000 ppm.

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

[0019] In another embodiment, the present invention provides The present invention relates to an inorganic formed body containing the calcium carbonate compound.

[0020] By applying a cubic calcium carbonate compound to an inorganic molded body, it is possible to efficiently obtain a strong inorganic molded body while maintaining fluidity and good workability during the manufacturing process. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is an SEM photograph of the calcium carbonate compound of Example 1-1 of the present invention. [Figure 2] 1 is an SEM photograph of the calcium carbonate compound of Comparative Example 1-1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] 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.

[0023] <Calcium carbonate compounds> The calcium carbonate compound according to this embodiment is cubic and suitable for use in inorganic molded bodies.

[0024] The calcium carbonate compound has an average particle size of preferably 2 μm to 25 μm, more preferably 4 μm to 22 μm, and even more preferably 6 μm to 18 μm, as measured by a laser diffraction method. This allows the fluidity of the mixture containing the calcium carbonate compound to be favorably maintained. In addition, the strength of the resulting inorganic molded body can be further improved.

[0025] The BET specific surface area of ​​the calcium carbonate compound is 0.3 m 2 / g or more 3m 2 / g or less, and 2 / g or more 2.6m 2 / g or less is more preferable, and 0.5m 2 / g or more 2.4m 2 / g or less. This makes it possible to maintain the fluidity of the mixture containing the calcium carbonate compound in a suitable manner, and also improve the dispersibility of the calcium carbonate compound. In addition, the strength of the resulting 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, and even more preferably 1.10 g / mL or more and 1.60 g / mL or less. This allows the fluidity of the mixture containing the calcium carbonate compound to be favorably maintained. In addition, the density and strength of the calcium carbonate compound are increased, further improving the strength of the resulting inorganic molded body.

[0027] The flow time of the calcium carbonate compound through a P funnel is preferably 7 to 10 seconds, more preferably 7.5 to 9.8 seconds, and even more preferably 8 to 9.5 seconds. The calcium carbonate compound is cubic, so it can exhibit excellent fluidity.

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

[0029] The crystal structure of the calcium carbonate compound may be a calcite type, an aragonite type, or a combination thereof. In order to obtain 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 rare.

[0030] In the X-ray diffraction measurement of the calcium carbonate compound, the peak intensity of aragonite I a Calcite peak intensity I c Ratio to I a / I c is preferably 0.1 or less, more preferably 0.08 or less, and even more preferably 0.06 or less, whereby 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 of producing calcium carbonate compounds) The method for producing a calcium carbonate compound is not particularly limited, and any known production method can be used. Typically, a solution method can be suitably used in which a calcium carbonate compound is produced by contacting a carbonate (carbonate ion) with calcium (calcium ion) from seawater or the like to carry out salt exchange. Ca 2+ +CO3 2- →CaCO3(A)

[0033] The carbonate ion salt used in reaction formula (A) may be an alkali metal salt (Li, Na, K) or an alkaline earth metal salt (Mg, Sr, but excluding Ca), with the alkali metal salt being preferred. Of these, sodium carbonate (sodium carbonate) is preferred in terms of versatility and cost.

[0034] The carbonate may be brought into contact with seawater or the like by adding an aqueous solution or slurry of the carbonate to seawater or the like, or by adding seawater or the like to the aqueous solution or slurry. The addition is preferably carried out all at once, since the desired cubic calcium carbonate compound can be efficiently obtained.

[0035] Seawater may be directly drawn from a nearby ocean, or may be filtered before use. Drawing seawater is not limited to nearby waters, and it may be taken from any location where seawater is available. Calcium-rich seawater, which is produced when magnesium hydroxide is removed from seawater, may also be used.

[0036] The amount of carbonate salt to be added is not particularly limited as long as it is set so as to obtain the amount of carbonate ions necessary for the reaction with the amount of calcium ions in seawater, etc., according to the above reaction formula (A). Although the amount of calcium ions and the amount of carbonate ions are preferably equimolar, the molar ratio of the amount of carbonate ions to the amount of calcium ions may be within a range of ±50 to 200%.

[0037] The salt exchange reaction caused by contact of carbonate with seawater or the like proceeds relatively quickly. The reaction time may be set to a time sufficient for the salt exchange reaction to proceed sufficiently, and can be set to 1 second or more, preferably 1 minute to 60 minutes, and more preferably 5 minutes to 50 minutes.

[0038] 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.

[0039] <Inorganic molded body> The inorganic molded body is not particularly limited, and typical examples include molded boards for building materials, concrete structures (concrete molded bodies), etc. Applicable compositions and the like will be described in detail below according to the application.

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

[0041] (hydraulic material) 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.

[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 even more preferably 10% by mass or more and 40% by mass or less, based on the total amount of materials constituting the molded board. By setting the content of the hydraulic material within the above range, it is possible to improve the physical properties of the molded board, such as bending strength and peel strength, and to prevent the molded board from becoming too high in bulk density, thereby improving workability during construction.

[0043] (siliceous material) Examples of siliceous materials include materials containing a large amount of SiO, such as silica sand, silica powder, silica fume, fly ash, diatomaceous earth, layered silicates (e.g., mica, talc, kaolin, bentonite), wollastonite, and lightweight aggregates (e.g., fly ash balloons, perlite, shirasu balloons, glass foam, etc.). 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, as described below.

[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 even more preferably 15% by mass or more and 45% by mass or less, based on the total amount of materials constituting the molded board. 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 molded board within the desired range. Incidentally, as the siliceous material, perlite, fly ash balloons, shirasu balloons, etc., having a unit volume mass of 0.5 g / cm are preferred. 3 When mixing the following lightweight aggregates, 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 molded board, in order to prevent the bulk density from becoming too light and weakening strength such as bending strength and peel strength.

[0045] (reinforcing fiber material) Examples of reinforcing fiber materials that can be used include pulps such as softwood pulp, hardwood pulp, fibrillated pulps 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.

[0046] To improve the strength and toughness of the molded board, the content of the reinforcing fiber material is preferably 2% by mass to 30% by mass, more preferably 3% by mass to 26% by mass, and even more preferably 4% by mass to 22% by mass, based on the total amount of materials constituting the molded board. By setting the content of the reinforcing fiber material within this range, it is possible to achieve a sufficient reinforcing effect while suppressing the protrusion of fibers from the surface of the molded board, thereby improving smoothness. When an inorganic reinforcing fiber material with an average length of 1 mm to 50 mm is blended as the reinforcing fiber material, it is preferable to use another reinforcing fiber material in combination so that the content is 10% by mass or less, based on the total amount of materials constituting the molded board, in order to improve the smoothness of the molded board.

[0047] (Calcium carbonate compounds) As the calcium carbonate compound, the calcium carbonate compounds described above can be suitably used.

[0048] 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 molded board. By blending a calcium carbonate compound with low thermal conductivity in the above content range, the strength and fire resistance of the molded board can be improved.

[0049] (optional ingredient) In addition to the above materials, various materials can be blended into the molded board depending on the purpose to impart various functions, 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. It is also possible to add recycled materials made by crushing scraps generated during the processing of the molded board as appropriate.

[0050] The bulk density of the molded plate is 0.7 g / cm 3 More than 2.0g / cm 3 Preferably, it is 0.8 g / cm or less. 3 More than 1.8g / cm 3 More preferably, it is 0.9 g / cm or less. 3 More than 1.6g / cm 3 It is even more preferable that:

[0051] (Method of manufacturing molded plate) The method for producing the molded plate according to this embodiment is not particularly limited, and commonly used methods such as papermaking, extrusion, flow-on molding, casting, and press (compression) molding can be used. The molded plate can be obtained by subjecting a green sheet molded by these methods to press dehydration or patterning by embossing, etc., followed by curing at room temperature, steam curing, autoclave curing, etc. The molded plate can then be dried and, if necessary, shaped or painted.

[0052] (Uses of molded boards) The uses of the molded board are not particularly limited, and it can be suitably used as a performance maintaining material for wall construction, flooring, roofing, various boards, exterior decorative members, interior and exterior finishing materials such as fittings, sealing materials, heat insulating materials, sound absorbing materials, waterproofing materials, etc. The molded board is preferably a cementitious molded board containing a cementitious material, and more preferably a calcium silicate molded body.

[0053] (concrete structures) The concrete structure is composed of a hardened hydraulic composition. The hydraulic composition is made of a powder containing a calcium carbonate compound and at least one of blast furnace slag, expansive agent, slaked lime, quicklime, fly ash, and Portland cement. The calcium carbonate compound may be any of the calcium carbonate compounds described above.

[0054] 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.

[0055] The hardened hydraulic composition is obtained by hardening a paste obtained by kneading the hydraulic composition with water. 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.

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

[0057] It is desirable to use ground granulated blast furnace slag used in JIS (Japanese Industrial Standards) R5211 "Blast furnace cement" or ground granulated blast furnace slag conforming to JIS A6206 "Blast furnace slag for concrete." In addition, blast furnace slag should have a specific surface area of ​​2000 to 10000 cm. 2 / g, preferably 3500 to 7000 cm 2 It is desirable to use one with a saturation of 0.15 to 0.25 g.

[0058] The expansive material may be, for example, one specified in JIS A6202 “Expansive materials for concrete.” The expansive material is preferably added in an amount of 2 to 9 mass % based on the total amount of the hydraulic composition.

[0059] For example, slaked lime specified in JIS R9001 "Industrial Lime" can be used. Furthermore, because quicklime becomes slaked lime when it comes into contact with water, quicklime specified in JIS R9001 "Industrial Lime" can be used instead of slaked lime. In this case, it is advisable to adjust the amount of water required to convert quicklime into slaked lime. The fly ash used may be one that conforms to JIS A6201 "Fly ash for concrete," for example.

[0060] Ordinary Portland cement is used as Portland cement, but other types of Portland cement such as high-early-strength Portland cement, ultra-high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement, as specified in JIS R5210 "Portland cement," and JIS R5214 "Ecocement" can also be used.

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

[0062] Furthermore, when Portland cement and blast furnace slag or fly ash are used, the components may be pre-mixed, for example, JIS R5211 "blast furnace cement" or, for example, JIS R5213 "fly ash cement," and the pre-mixed components 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 mixture exhibit good fluidity, and the hardened concrete produced from the composition can exhibit excellent compressive strength.

[0064] The density of the concrete structure is 0.7 g / cm 3 More than 2.0g / cm 3 Preferably, it is 0.8 g / cm or less. 3 More than 1.8g / cm 3 More preferably, it is 0.9 g / cm or less. 3 More than 1.6g / cm 3 It is even more preferable that: [Example]

[0065] 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.

[0066] <Evaluation of calcium carbonate compounds> The calcium carbonate compounds obtained in each production example were analyzed as follows. The analytical results are shown in Table 1 and Figures 1 and 2.

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

[0068] (2) Average particle size by laser diffraction method 50 mL of ethanol was taken in a 100 mL beaker, and about 0.2 g of the sample powder was put into the 100 mL beaker described above, and ultrasonic treatment (UD-201 manufactured by Tomy Seiko Co., Ltd.) was performed for 3 minutes to prepare a dispersion liquid. This dispersion liquid was measured using a laser diffraction method - particle size distribution meter (Microtrac HRA Model 9320-X100 manufactured by Nikkiso Co., Ltd.) with 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> Weighed 0.2 g of calcium-based carbonate compound as a sample, moistened it with water, added 10 mL of hydrochloric acid (a liquid obtained by mixing concentrated hydrochloric acid and water in a volume ratio of 1:1) with a pipette, and heated and dissolved it. After cooling, it was transferred to a 250 mL volumetric flask, and water was added to make up to 250 mL. 20 mL was taken from this and transferred to a 50 mL volumetric flask, and water was added to make up to 50 mL to obtain a test liquid for measurement. On the other hand, 20 mL was taken from the 250 mL made-up aqueous solution described above and transferred to 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 atomic absorption standard solutions (commercially available).

[0071] The calibration standard solutions with different concentrations to which each element was added and the test liquid for measurement were set in the autosampler of an inductively coupled plasma optical 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: Aqueous Number of integrations: 3 Sample order: each sample Measurement method: Standard addition method Calibration curve weighting: None Measurement wavelength: magnesium atom 279.553 nm

[0072] (5) 46° (aragonite) peak intensity I by XRD measurement a 29° (calcite) peak intensity I c Calculating the ratio to The sample powder was pressed and fixed onto a designated sample stage with a spatula, and then measured using an XRD device (MiniFlex600-C manufactured by Rigaku Corporation) to identify the material as a crystalline substance. 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 46° (aragonite) peak intensity I a 29° (calcite) peak intensity I c Ratio to (I a / I c ) was sought.

[0073] (6) Scanning electron microscope observation Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied to the tape by tracing it with a spatula. After platinum deposition, particle images of the sample powder were taken at 2,000 magnifications using a scanning electron microscope (FE-SEM: S-4700, manufactured by Hitachi, Ltd.). Figures 1 and 2 show SEM images of the example and comparative example.

[0074] <Production of calcium carbonate compounds> [Example 1-1] Calcium carbonate compound (cubic) A sodium carbonate solution was prepared by adding 8510 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries, purity 99.8%) to a 220 L stainless steel vessel with a baffle and containing 100 L of water under stirring.2+ The calcium carbonate solution (content: 0.25 g / dL) was placed in a 2000 L polyethylene container, and 100 L of the sodium carbonate solution mentioned above was added all at once while stirring. The reaction was allowed to proceed by continuing to stir for about 30 minutes. The solid was then filtered, washed with about five times the amount of water as the solid content, dried at 110°C for 24 hours, and pulverized to obtain a sample powder of a calcium carbonate compound.

[0075] [Example 1-2] Calcium carbonate compound (cubic) A sample powder of calcium carbonate compound was obtained by the same procedure as in Example 1-1, except that 12.7 kg of magnesium chloride hexahydrate was added to 1,000 L of seawater after removing magnesium hydroxide from the seawater under stirring, and then 100 L of the above-mentioned sodium carbonate aqueous solution was added all at once.

[0076] [Examples 1-3] Calcium carbonate compound (cubic) To 100 L of seawater from which magnesium hydroxide had been removed, 10 L of the aforementioned sodium carbonate aqueous solution was added all at once under stirring, and stirring was continued for approximately 30 minutes. Using this post-reaction liquid as a seed, 100 L of seawater from which magnesium hydroxide had been removed was added, and 10 L of the aforementioned sodium carbonate aqueous solution was added all at once under stirring, and stirring was continued for approximately 30 minutes. This series of operations was repeated a total of 10 times. Apart from these operations, the same operations as in Example 1-1 were carried out to obtain a sample powder of a calcium carbonate compound.

[0077] [Comparative Example 1-1] Calcium carbonate compound (needle-shaped) Commercially available slaked lime powder (Yoshimi Sekki Kogyo Co., Ltd., industrial best quality slaked lime) is converted to CaO at 69 80 g of seed crystal powder of aragonite, 630 g, and 3000 g of disodium hydrogen phosphate dodecahydrate were prepared, and each was charged 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, a stirrer equipped with a single-stage turbine blade was used to stir at a rotation speed of 150 rpm. 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 of a cement molded body and a compressive strength test 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 mixed with a stirrer (Lab Stirrer (LR500B) manufactured by Yamato Scientific Co., Ltd.) 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 (POM-made stirring rod φ10×300 mm manufactured by AS ONE Corporation) to prepare cement milk 1.

[0081] (Preparation of cement milk 2 to 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 the mixture was stirred manually with the stirring rod for about 30 seconds, and then stirred at 400 rpm using the stirrer to obtain a mixture. 2 kg of cement (Tokuyama Corporation, "Normal Portland Cement (N)") was added to this mixture over about 20 seconds, and the mixture was mixed with the stirrer for 3 minutes from the start of addition. The stirring was stopped, the mixture was left to stand for 3 minutes, and then the mixture was manually stirred 10 times with the stirring rod to prepare cement milks 2 to 7.

[0082] [Table 2-1]

[0083] (Preparation of cement milk 8-10) Cement milks 8 to 10 were prepared in the same manner as in the preparation of cement milks 2 to 7, except that the calcium carbonate compound of Example 1-2 was used in the type and amount shown in Table 2-2 below.

[0084] [Table 2-2]

[0085] (Preparation of cement milk 11 to 13) Cement milks 11 to 13 were prepared in the same manner as in the preparation of cement milks 2 to 7, except that the calcium carbonate compounds of Examples 1 to 3 were used in the types and amounts shown in Table 2-3 below.

[0086] [Table 2-3]

[0087] (P funnel flow time test method) The P funnel flow time was measured in accordance with the "Test method for fluidity of injection mortar for prepacked concrete (method using P funnel)" (JSCE-F521-1999). The outlet of the P funnel was held with a finger, and each of the prepared cement milks was poured up to the mark on the P funnel (1750 ml). Measurement was started as soon as the finger was released using a time watch, and the time until the cement milk was discharged from the P funnel was measured.

[0088] <Production of cement molded body> [Example 2-1] 400 mL of the prepared cement milk 1 was poured into a cylindrical polyethylene bag (approximately 50 mm in diameter x approximately 550 mm in length x approximately 0.05 mm in thickness) up to the marked line. After injecting as much air as possible and sealing the bag, the bag was hung in an incubator set at 22°C. The bag was left hanging in the incubator for 28 days to harden the contents, producing a total of three cement molded bodies. The resulting cement molded bodies were cylindrical, approximately 5 cm in diameter and 20 cm in length.

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

[0090] (density) The density was measured in accordance with JIS A 5430:2008 (apparent density test).

[0091] (Compression strength test) The compressive strength of the resulting cement compact was measured in accordance with JIS A 1108:2018 (Method for compressive testing of concrete).

[0092] [Table 3-1]

[0093] [Table 3-2]

[0094] [Table 3-3]

[0095] In the cement milk using the calcium carbonate compound of the example, even if the content of the calcium carbonate compound was increased, there was no significant increase in the P funnel flow time compared to Comparative Example 2-1, which did not contain a calcium carbonate compound, and the cement milk had good fluidity. On the other hand, in Comparative Examples 2-2 to 2-4, the fluidity decreased significantly as the content of the calcium carbonate compound was increased.

[0096] Furthermore, the cement moldings of the Examples had improved compressive strength compared to Comparative Example 2-1 by blending a calcium carbonate compound. Meanwhile, in Comparative Examples 2-2 to 2-4, even though a calcium carbonate compound was blended, the compressive strength decreased compared to the blank Comparative Example 2-1. While the reason for the decrease in compressive strength relative to the blank in Comparative Examples 2-2 to 2-4 is unclear, it is presumed that this is due to the fact that the calcium carbonate compounds are needle-shaped, which increases their surface energy, causing aggregation and reducing the reinforcing effect, and that the needle-shaped structure increases the viscosity of the cement milk, making it difficult for air bubbles to escape, resulting in the cement moldings with air bubbles remaining.

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

Claims

1. A BET specific surface area of ​​0.3 m 2 / g or more and 3 m 2 / g or less, A cubic calcium carbonate compound powder for use in inorganic moldings.

2. 2. The calcium carbonate compound powder according to claim 1, wherein the average particle size measured by a laser diffraction method is 2 μm or more and 25 μm or less.

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

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

5. 2. The calcium carbonate compound powder according to claim 1, wherein the magnesium content is 1000 ppm or more.

6. The calcium-based carbonate compound powder according to claim 1 , wherein the calcium-based carbonate compound powder is a synthetic calcium-based carbonate compound powder.

7. An inorganic molded body comprising the calcium carbonate compound powder according to any one of claims 1 to 6.

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