JP7710084B2 - Calcium carbonate compounds and inorganic moldings - Google Patents

Description

The present invention relates to calcium carbonate compounds and inorganic molded bodies.

Inorganic molded bodies are molded bodies that are mostly composed of inorganic substances such as hydraulic materials and siliceous materials, and because they have properties such as fire resistance, light weight, high strength, and ease of work, they are widely used for exterior wall materials for houses, roof underlayment materials, eaves ceiling materials, etc. They are also widely used in the foundations, walls, pillars, floors, etc. of buildings where strength and fire resistance are required.

A technique for incorporating needle-shaped calcium carbonate has been proposed as a way to increase strength, one of the important properties required of inorganic molded bodies (Patent Publication No. 6898926).

Patent No. 6898926

However, even with this technology, the strength of the inorganic molded body obtained may be reduced, and the fluidity of the mixture of raw materials during the manufacturing process may decrease, which may result in a decrease in the work efficiency of the entire manufacturing process.

The present invention aims to provide a calcium carbonate compound and an inorganic molded body that can improve the strength of the molded body while maintaining the fluidity of the mixture during the manufacturing process.

As a result of extensive research, the inventors discovered that the above problems could be solved by the following configuration, and thus completed the present invention.

In one embodiment, the present invention comprises:
The content of phosphorus atoms is 1000 ppm or less,
The present invention relates to a cubic calcium carbonate compound having a sulfur atom content of 100 ppm or more.

As a result of the inventors' investigations, they have newly discovered that phosphorus atoms act as a factor promoting needle-like or rod-like formation (hereinafter collectively referred to as "needle-like formation, etc.") that results in a high aspect ratio during crystal growth of calcium carbonate compounds, while sulfur atoms act as a factor inhibiting needle-like formation, etc. The calcium carbonate compounds have phosphorus and sulfur atom contents within a specific range, so that the shape can be efficiently controlled to a cube.

On the other hand, in the field of inorganic molded bodies, 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 molded bodies. 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 there is a trade-off between improving strength and maintaining fluidity. After extensive research, the inventors unexpectedly found that a cubic calcium carbonate compound can improve the strength of the resulting inorganic molded body while maintaining the fluidity of the mixture during the manufacturing process.

The present invention was completed by developing these new findings.

Although the reason why the calcium carbonate compound can achieve both fluidity and strength is unclear, it is speculated 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 isotropy (non-orientation) in the mixture allows for homogeneous dispersion or homogeneous filling, etc., which can improve the strength of the inorganic molded body. 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 fluidity and isotropy described above, so it is speculated that this also makes it possible to prevent or improve the decrease in strength.

In this specification, "cubic" refers to a shape that can be considered as a cube, not limited to a regular cube shape. For example, if one or more of the vertices of a cube are rounded or missing, but the cube can be restored by complementing the missing parts, the cube is cubic. In addition, if the length of one side of the target shape is within a range of 50% to 150% of the length of the other side, the target shape is cubic. Furthermore, the shape of one side of the target shape is not limited to a square, and may be any of a trapezoid, a rhombus, a rectangle with four sides of different lengths, etc., as long as the length ratio of the two sides is satisfied. In addition, it is not necessary for all particles constituting the calcium carbonate compound to be cubic, and the calcium carbonate compound is cubic when the proportion of cubic particles among all particles is the largest.

In this specification, the term "calcium carbonate compound" refers to a compound that contains calcium carbonate as a main component, and 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 carbonate compound is preferably 90% by mass or more. The disodium ethylenediaminetetraacetate titration method can be suitably used as a method for measuring the calcium carbonate content in the calcium carbonate compound.

<Disodium ethylenediaminetetraacetate titration method>
1 g of calcium carbonate compound (dried at 105°C for 2 hours) is weighed out as a sample, suspended in 50 mL of water, and 10 mL of hydrochloric acid (a mixture of concentrated hydrochloric acid and water in a 1:1 volume ratio) is added, and the mixture is heated and dissolved. After cooling, the mixture is transferred to a 250 mL measuring flask, and water is added to the same amount. 5.00 mL is taken from this, and water is added so that the total amount of the liquid is about 50 mL. 5 mL of buffer solution (a solution of 1,000 mL of 500 g of potassium hydroxide dissolved in water) is added to this, and further, commercially available Dotite NN diluted powder is added, and the mixture is titrated with a titration reagent (a solution of 1,000 mL of 3.8 g of disodium ethylenediaminetetraacetate dissolved in water). The titration is terminated when the color of the liquid changes from red to blue. The calcium carbonate content (%) is calculated using the following formula.

(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).)

In one embodiment, the calcium carbonate compound preferably 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 preferably has a BET specific surface area of 0.3 m ² /g or more and 3 m ² /g or less. In one embodiment, the calcium carbonate compound preferably has an apparent specific gravity of 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 compatibility between fluidity and strength.

In one embodiment, the calcium carbonate compound can achieve a P funnel flow time of 7 seconds or more and 10 seconds or less. This allows the calcium carbonate compound to exhibit good fluidity.

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

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

In another embodiment, the present invention provides a method for producing a pharmaceutical composition comprising the steps of:
The present invention relates to an inorganic formed body containing the calcium carbonate compound.

By applying a cubic calcium carbonate compound to an inorganic molding, it is possible to efficiently obtain a strong inorganic molding while maintaining the fluidity and good workability during the manufacturing process.

1 is a SEM photograph of the calcium carbonate compound of Example 1-1 of the present invention. 1 is a SEM photograph of a calcium carbonate compound of Comparative Example 1-1 of the present invention.

The calcium carbonate compound and inorganic molded body according to one embodiment of the present invention are described below. The present invention is not limited to these embodiments.

<Calcium carbonate compounds>
The calcium carbonate compound according to the present embodiment has a cubic shape, and the calcium carbonate compound has a phosphorus atom content of 1000 ppm or less and a sulfur atom content of 100 ppm or more.

In calcium carbonate compounds, the phosphorus atom content is not particularly limited as long as it is 1000 ppm or less. The phosphorus atom content is preferably 500 ppm or less, and more preferably 100 ppm or less. On the other hand, the lower the phosphorus atom content, the better, but it may be present in an amount of about 1 ppm. By setting the phosphorus atom content, which is one factor in the needle-like formation of calcium carbonate compounds, to the above-mentioned specified amount, cubic calcium carbonate compounds can be efficiently formed.

In the calcium carbonate compound, the content of sulfur atoms is not particularly limited as long as it is 100 ppm or more. It is preferably 500 ppm or more, and more preferably 1000 ppm or more. The content of sulfur atoms is preferably 10000 ppm or less, and more preferably 5000 ppm or less. By setting the content of sulfur atoms to the above-mentioned predetermined amount, it is possible to inhibit needle formation, etc., and a cubic calcium carbonate compound can be efficiently obtained.

The average particle size of the calcium carbonate compound measured by laser diffraction 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. This makes it possible to favorably maintain the fluidity of the mixture containing the calcium carbonate compound. In addition, the strength of the resulting inorganic molded body can be further improved.

The BET specific surface area of the calcium carbonate compound is preferably 0.3 ^m2 /g or more and 3 ^m2 /g or less, more preferably 0.4 ^m2 /g or more and 2.6 ^m2 /g or less, and even more preferably 0.5 ^m2 /g or more and 2.4 ^m2 /g or less. This makes it possible to favorably maintain the fluidity of the mixture containing the calcium carbonate compound, and also to improve the dispersibility of the calcium carbonate compound. In addition, the strength of the resulting inorganic molded body can be further improved.

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 makes it possible to favorably maintain the fluidity of the mixture containing the calcium carbonate compound. In addition, the density and strength of the calcium carbonate compound are increased, and the strength of the resulting inorganic molded body can be further improved.

The P funnel flow time of the calcium carbonate compound 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, and therefore exhibits excellent fluidity.

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, depending on the raw materials and manufacturing method.

As the crystal structure of the calcium carbonate compound, a calcite type, an aragonite type, or a combination of these can be suitably 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 infrequent.

In the X-ray diffraction measurement of the calcium carbonate compound, the ratio _Ia / _Ic of the peak intensity _Ia of aragonite to the peak intensity _Ic of calcite is preferably 0.1 or less, more preferably 0.08 or less, and even more preferably 0.06 or less, so that a cubic calcium carbonate compound can be efficiently obtained.

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

(Method for producing calcium carbonate compound)
The method for producing the calcium carbonate compound is not particularly limited, and a known production method can be adopted. Typically, a solution method can be preferably adopted in which a carbonate (carbonate ion) is brought into contact with calcium (calcium ion) from seawater or the like to carry out salt exchange to produce the calcium carbonate compound.
Ca ²⁺ +CO ₃ ^2- →CaCO ₃ (A)

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

The carbonate may be brought into contact with seawater or the like by pouring an aqueous solution or slurry of the carbonate into seawater or the like, or by pouring seawater or the like into the aqueous solution or slurry. It is preferable to pour all at once, since this allows the desired cubic calcium carbonate compound to be obtained efficiently.

Seawater may be directly drawn from a nearby ocean, or may be filtered or otherwise processed before use. Drawing seawater is not limited to nearby oceans, and may be done anywhere seawater is available. Calcium-rich seawater that is produced when magnesium hydroxide is removed from seawater may also be used.

The amount of carbonate added is not particularly limited as long as it is set so as to obtain the amount of carbonate ions required for the reaction with the amount of calcium ions in seawater or the like 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%.

The salt exchange reaction caused by contact between carbonates and seawater etc. 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 or more and 60 minutes or less, and more preferably 5 minutes or more and 50 minutes or less.

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

<Applications of calcium carbonate compounds>
The use of the calcium carbonate compound is not particularly limited. For example, it is suitable as a high-performance material for inorganic molded bodies, such as building materials and buildings, a filler for resins, etc. Hereinafter, an embodiment in which the calcium carbonate compound is used for an inorganic molded body will be described.

<Inorganic Molded Body>
The inorganic molded body is not particularly limited, and representative examples include molded boards for building materials, concrete buildings (concrete molded bodies), etc. Applicable compositions and the like will be described in detail below according to the applications.

(Formed boards for building materials)
The molded plate preferably contains a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium carbonate compound.

(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, dihydrate gypsum, etc. Examples of slag include blast furnace slag, converter slag, etc. These hydraulic materials can be used alone or in combination of two or more.

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 keeping 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 suppress the molded board from becoming too high in bulk density, thereby improving workability during construction, etc.

(siliceous material)
Examples of siliceous materials include materials containing a large amount of SiO 2, 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 foams, 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 described below.

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 the materials constituting the molded board. If the content of the siliceous material is within the above range, it is possible to set the bending strength, bulk density, water absorption rate, dimensional stability, etc. of the molded board to the desired range. In addition, when a lightweight aggregate having a unit volume mass of 0.5 g/ ^cm3 or less such as perlite, fly ash balloon, and shirasu balloon is mixed as the siliceous material, 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 board, in order to prevent the bulk density from becoming too light and the strength such as bending strength and peel strength from being weakened.

(Reinforcing fiber material)
Examples of reinforcing fiber materials that can be used include pulps such as softwood pulp, hardwood pulp, pulps fibrillated with these pulps, and pulps 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.

In order to improve the strength and toughness of the molded board, 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 molded board. By setting the content of the reinforcing fiber material within the above range, it is possible to suppress the protrusion of fibers on the surface of the molded board while exerting a sufficient reinforcing effect, 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 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 molded board, in order to improve the smoothness of the molded board.

(Calcium carbonate compounds)
As the calcium carbonate compound, the above-mentioned calcium carbonate compounds can be suitably used.

The content of 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 calcium carbonate compound with low thermal conductivity in the above content range, the strength and fire resistance of the molded board can be improved.

(optional ingredient)
In addition to the above materials, various materials such as hollow resin bodies, wood chips, wood powder, resin powder, defoamers, flocculants, water repellents, thickeners (methylcellulose, hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, etc.), dispersants, etc. can be mixed into the molded board depending on the purpose in order to impart various functions. It is also possible to appropriately add recycled materials made by crushing scraps generated during processing of the molded board.

The bulk density of the molded 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 even more preferably 0.9 g/cm ³ or more and 1.6 g/cm ³ or less.

(Method of manufacturing molded plate)
The method for producing the molded plate according to the present embodiment is not particularly limited, and generally 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 a patterning process such as press dehydration or embossing, and then curing the green sheet at room temperature, steam, or autoclave. The molded plate may be further dried and, if necessary, shaped or painted.

(Uses of molded plates)
The uses of the molded board are not particularly limited, and the molded board can be suitably used as a wall material, a floor material, a roof material, various boards, external decorative members, interior and exterior finishing materials such as fittings, sealing materials, heat insulating materials, sound absorbing materials, waterproofing materials, and other performance maintaining materials. The molded board is preferably a cementitious molded board containing a cementitious material, and more preferably a calcium silicate molded body.

(Concrete Structures)
The concrete structure 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 carbonate compound. The calcium carbonate compound described above can be suitably used as the calcium carbonate compound.

In addition to the above hydraulic composition, aggregates such as sand and gravel, chemicals such as chemical admixtures for concrete, and fibrous materials made of metals or polymeric materials may be added to form a hydraulic composition mixture.

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

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

It is preferable 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, it is preferable to use blast furnace slag with a specific surface area of 2000 to 10000 ^cm2 /g, preferably 3500 to 7000 ^cm2 /g.

For example, the expansive agent may be one specified in JIS A6202 "Expansive agents for concrete." It is desirable to add the expansive agent in an amount of 2 to 9% by mass relative to the total hydraulic composition.

For example, slaked lime specified in JIS R9001 "Industrial lime" may be used. In addition, quicklime becomes slaked lime when it comes into contact with water, so quicklime specified in JIS R9001 "Industrial lime" may be used instead of slaked lime. In this case, it is advisable to correct the amount of water required for quicklime to change into slaked lime.
The fly ash used may be one that conforms to JIS A6201 "fly ash for concrete", for example.

Ordinary Portland cement is used as the Portland cement, but other types of Portland cement that can be used include high-early-strength Portland cement, ultra-high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, sulfate-resistant Portland cement, and other types specified in JIS R5210 "Portland cement," as well as JIS R5214 "Ecocement."

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.

When using Portland cement and blast furnace slag or fly ash, the components may be premixed, for example, JIS R5211 "blast furnace cement" or JIS R5213 "fly ash cement," either alone or in combination.

Because the calcium carbonate compound having the above characteristics is used, the hydraulic composition and hydraulic composition mixture exhibit good fluidity, and the resulting hardened concrete exhibits excellent compressive strength.

The density of the concrete structure is preferably 0.7 g/cm3 or ^more and 2.0 g/ ^cm3 or less, more preferably 0.8 g/ ^cm3 or more and 1.8 g/ ^cm3 or less, and even more preferably 0.9 g/ ^cm3 or more and 1.6 g/ ^cm3 or less.

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 deviate from the gist of the invention. Measurements and evaluations of physical properties were performed as follows.

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

(1) BET Specific Surface Area A powder sample was pretreated in a nitrogen gas atmosphere at about 130°C for about 30 minutes using an 8-unit preheat unit (manufactured by MOUNTECH), and the BET specific surface area ( ^m2 /g) was measured by a nitrogen gas adsorption method using a Macsorb HM Model-1208 (manufactured by MOUNTECH) as a BET specific surface area measuring device.

(2) Average particle size by laser diffraction method 50 mL of ethanol was placed in a 100 mL beaker, and about 0.2 g of the sample powder was placed in the 100 mL beaker and subjected to ultrasonic treatment (UD-201, manufactured by Tommy Seiko Co., Ltd.) for 3 minutes to prepare a dispersion. This dispersion was measured using a laser diffraction method-particle size distribution meter (Microtrac HRA Model 9320-X100, manufactured by Nikkiso Co., Ltd.) to measure the volume-based _D50 value as the average particle size (μm).

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

(4) Content of phosphorus atom, sulfur atom and magnesium atom <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 mixture of concentrated hydrochloric acid and water in a 1:1 volume ratio) was added using a dispenser, and the mixture was heated and dissolved. After cooling, the mixture was transferred to a 250 mL measuring flask, and water was added to the flask until the volume reached 250 mL. 20 mL was then dispensed into a 50 mL measuring flask, and water was added to the flask until the volume reached 50 mL to prepare a sample solution for measurement. Meanwhile, 20 mL was dispensed into a 50 mL measuring flask from the aqueous solution that had been dispensed to the 250 mL level, and standard solutions of each element (phosphorus atom, sulfur atom, and magnesium atom) were added at random to prepare standard solutions for calibration curves with different concentrations. The standard solutions for each element were 1000 ppm atomic absorption standard solutions (commercially available).

The calibration standard solutions with different concentrations of each element added and the measurement sample solutions were placed in the autosampler of an inductively coupled plasma atomic emission spectrometry (ICP-AES) device (Hitachi High-Tech Science Corporation, "SPECTROBLUE FMS36 Model"), 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
Liquidity: Aqueous solution Number of integrations: 3 Sample order: For each sample Measurement method: Standard addition method Weighting of calibration curve: None Measurement wavelength: Phosphorus atom 177.495 nm, sulfur atom 182.034 nm, magnesium atom 279.553 nm

(5) Calculation of the ratio of the 46° (aragonite) peak intensity Ia _to the 29° (calcite) peak intensity _Ic by XRD measurement After the sample powder was pressed and fixed on a specified sample stage with a spatula, measurement was performed using an XRD device (MiniFlex600-C manufactured by Rigaku Corporation) to perform identification analysis as a crystalline substance. Note that, at the measurement angle 2θ, the peak appearing at about 29° is the main peak of calcite, and the peak appearing at about 46° is the main peak of aragonite. From this, the ratio ( _Ia / _Ic ) of the 46° (aragonite) peak intensity _Ia to the 29° (calcite) peak intensity _Ic was calculated.

(6) Scanning Electron Microscope Observation Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied on top of it by tracing it with a spatula. After platinum deposition, the particle images of the sample powder were photographed at 2,000 times magnification using a scanning electron microscope (FE-SEM: S-4700 manufactured by Hitachi, Ltd.). Figures 1 and 2 show SEM photographs of the examples and comparative examples.

<Production of calcium carbonate compound>
[Example 1-1] Calcium carbonate compound (cubic)
Sodium carbonate was prepared by adding 8510 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries, purity 99.8%) under stirring into a 220 L SUS vessel with a baffle plate, which had been filled with 100 L of water in advance. Meanwhile, 1000 L of seawater (Ca2 ⁺ content: 0.25 g/dL) obtained by removing magnesium hydroxide from seawater discharged from Konoshima Chemical Co., Ltd. was placed in a 2000 L polyethylene vessel, and 100 L of the above-mentioned sodium carbonate aqueous solution was added at once under stirring at 25°C, and the reaction was continued for about 30 minutes. The mixture was then filtered, washed with about 5 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.

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

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

[Comparative Example 1-1] Calcium carbonate compound (needle-shaped)
Commercially available slaked lime powder (Yoshimi Sekiryo Kogyo Co., Ltd., industrial best quality slaked lime) is 69% CaO equivalent.
80g of aragonite seed crystal powder, 630g of aragonite seed crystal powder, and 3000g of disodium hydrogen phosphate dodecahydrate were prepared, and each was charged under stirring into a 220L SUS vessel with a baffle plate in which 180L of water had been previously filled, to prepare a mixed slurry of the raw materials. The temperature was then raised to 70°C, and the mixture was stirred at a rotation speed of 150 rpm using a stirrer equipped with one turbine blade at that temperature. A pipe for extracting exhaust gas was connected to the exhaust outlet of a steam production boiler using LNG as fuel, and the _CO2 concentration was measured using a CO2 concentration meter (XP-3140 manufactured by Shin Cosmos Electric Co., Ltd.) while drawing in the exhaust gas using a test blower. The _CO2 concentration was 10% by volume. Exhaust gas was introduced into the above-mentioned 220L SUS vessel using a test blower at a speed of 100L/min and reacted for 7 hours. Thereafter, the mixture was filtered, washed with about 5 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.

<Evaluation>
The calcium carbonate compound thus obtained was used to measure the flow time through a P funnel, produce a cement molded body, and carry out a compressive strength test. The results are shown in Table 3.

<P funnel flow time>
(Preparation of cement milk 1)
2 kg of cement (Tokuyama Corp., "Normal Portland Cement (N)") was added to 1600 mL of water in about 20 seconds, and mixed with a stirrer (Yamato Scientific Corp., "Labo Stirrer (LR500B)") for 3 minutes from the start of addition. After stopping the stirring and leaving it to stand for 3 minutes, the mixture was manually stirred 10 times with a stirring rod (As One Corp., "Stirring rod (POM) φ10 × 300 mm") to prepare cement milk 1.

(Preparation of cement milk 2 to 7)
The calcium carbonate compounds of Example 1-1 and Comparative Example 1-1 of the types and amounts shown in Table 2-1 below were added to 1600 mL of water, and after stirring manually with the stirring rod for about 30 seconds, the mixture was stirred at 400 rpm using the stirrer. 2 kg of cement (Tokuyama Corporation, "Normal Portland Cement (N)") was added to this mixture over about 20 seconds, and mixed with the stirrer for 3 minutes from the start of addition. Stirring was stopped and the mixture was left to stand for 3 minutes, after which cement milks 2 to 7 were prepared by manually stirring 10 times with the stirring rod.

(Preparation of cement milk 8 to 10)
Cement milks 8 to 10 were prepared in the same manner as for preparing 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.

(Preparation of cement milk 11 to 13)
Cement milks 11 to 13 were prepared in the same manner as for preparing cement milks 2 to 7, except that the calcium carbonate compound of Example 1-3 was used in the type and amount shown in Table 2-3 below.

(P funnel flow time test method)
The P funnel flow time was measured according to "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). The finger was released and the measurement was started at the same time with a time watch, and the time until the cement milk was discharged from the P funnel was measured.

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

[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 the cement milks shown in Tables 3-1 to 3-3 below were used.

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

(Compressive strength test)
The compressive strength of the obtained cement molded body was measured in accordance with JIS A 1108:2018 (compression test method for concrete).

In the cement milk using the calcium carbonate compound of the embodiment, 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.

Furthermore, in the cement molded body of the Example, the compressive strength was improved compared to Comparative Example 2-1 by blending a calcium carbonate compound. On the other hand, in Comparative Examples 2-2 to 2-4, the compressive strength was reduced compared to the blank Comparative Example 2-1, even though a calcium carbonate compound was blended. Note that the reason for the decrease in compressive strength compared to the blank in Comparative Examples 2-2 to 2-4 is unclear, but it is presumed that this is due to the calcium carbonate compound being needle-shaped, which increases the surface energy, causing aggregation and reducing the reinforcing effect, and the needle-shaped nature of the compound increases the viscosity of the cement milk, making it difficult for air bubbles to escape, resulting in the cement molded body being obtained with air bubbles remaining.

From the above, it was found that the cement milk using the calcium carbonate compound of the embodiment 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 (8)

The content of phosphorus atoms is 1000 ppm or less,
The content of sulfur atoms is 100 ppm or more,
The crystal structure is calcite type, aragonite type, or a combination thereof;
The apparent specific gravity is 1 g/mL or more and 2 g/mL or less.
A cubic calcium carbonate compound. The calcium carbonate compound 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. 2. The calcium carbonate compound according to claim 1, having a BET specific surface area of 0.3 m ² /g or more and 3 m ² /g or less. The calcium carbonate compound according to claim 1, having a P funnel flow time of 7 seconds or more and 10 seconds or less. The calcium carbonate compound according to claim 1, wherein the magnesium content is 1000 ppm or more. The calcium carbonate compound according to claim 1, wherein the calcium carbonate compound is a synthetic calcium carbonate compound. The calcium carbonate compound according to claim 1, which is for use in inorganic moldings. An inorganic formed body comprising the calcium carbonate compound according to any one of claims 1 to 7 .