Calcium carbonate compounds for inorganic moldings

Abstract

Provided is a calcium-based carbonate compound for an inorganic molded body, said compound being capable of sufficiently reducing cracking and warping during heating when used in an inorganic molded body that serves as a construction material. Specifically provided is a calcium-based carbonate compound for an inorganic molded body, said calcium-based carbonate compound having a calcite crystal structure, an aragonite crystal structure, or a combination thereof, wherein aspect ratio of the average major diameter to the average minor diameter is 2-19, and the oil absorption capacity is 40-90 mL / 100 g.

Description

[Technical Field]

[0001] The present invention relates to a calcium carbonate compound for use in 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 ease of work, they are widely used as exterior wall materials for houses, roof underlayment materials, eaves ceiling materials, etc.

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

[0004] As a technology to promote the reuse of waste materials while improving fire resistance, which is one of the important safety features required for inorganic molded bodies, a technology has been proposed in which seawater residue, which is mainly composed of calcium carbonate and magnesium hydroxide and is by-produced in the process of removing carbonates from seawater during the process of producing magnesium hydroxide from seawater, is applied to calcareous materials (JP 2012-116685 A). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-116685 Summary of the Invention [Problem to be solved by the invention]

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

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

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

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

[0010] In one embodiment, the present invention provides having a calcite-type crystal structure, an aragonite-type crystal structure, or a combination thereof; The aspect ratio of the average major axis to the average minor axis is 2 or more and 19 or less, Oil absorption is between 40mL / 100g and 90mL / 100g The present invention relates to a calcium carbonate compound for inorganic moldings.

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

[0012] In this specification, the term "calcium-based carbonate compound" refers to a compound containing calcium carbonate as a main component, 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-based carbonate compound is preferably 90 mass% or more. XRF (X-ray fluorescence analysis) can be suitably employed as a method for measuring the calcium carbonate content in the calcium-based carbonate compound.

[0013] In one embodiment, the apparent specific gravity of the calcium carbonate compound is preferably 0.1 g / mL or more and 1.0 g / mL or less, which improves the dispersibility of the calcium carbonate compound in the inorganic molded body and enables the shrinkage of the heating surface and the increase in the backside temperature during heating to be suppressed to a higher degree.

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

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

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

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

[0018] [Figure 1] 1 is an SEM photograph of the calcium carbonate compound of Example 1-1 of the present invention. [Figure 2] 1 is a SEM photograph of the calcium carbonate compound of Example 1-2 of the present invention. [Figure 3] 1 is an SEM photograph of the calcium carbonate compound of Example 1-3 of the present invention. [Figure 4] 1 is an SEM photograph of the calcium carbonate compound of Comparative Example 1-1 of the present invention. [Figure 5] FIG. 2 is a partial perspective view schematically showing a heating tester. DETAILED DESCRIPTION OF THE INVENTION

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

[0020] <Calcium carbonate compound for inorganic molding> The crystal structure of the calcium carbonate compound may be a calcite type, an aragonite type, or a combination thereof. In order to provide the calcium carbonate compound with the above aspect ratio, it is preferable that the calcium carbonate compound contains at least an aragonite type crystal structure.

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

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

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

[0024] The oil absorption of the calcium carbonate compound is preferably 40 mL / 100 g or more and 90 mL / 100 g or less, more preferably 45 mL / 100 g or more and 80 mL / 100 g or less, and even more preferably 50 mL / 100 g or more and 70 mL / 100 g or less. When the oil absorption of the calcium carbonate compound is within the above range, the dispersibility and fillability of the calcium carbonate compound can be improved, and as a result, shrinkage of the heating surface during heating and an increase in the back surface temperature can each be suppressed to a higher level.

[0025] The apparent specific gravity of the calcium carbonate compound is preferably 0.1 g / mL to 1.0 g / mL, more preferably 0.2 g / mL to 0.9 g / mL, and even more preferably 0.3 g / mL to 0.8 g / mL. By setting the apparent specific gravity of the calcium carbonate compound within this range, the dispersibility of the calcium carbonate compound in the inorganic molded body is improved, and shrinkage of the heating surface and an increase in the backside temperature during heating can be suppressed to a higher level.

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

[0027] The average particle size of the calcium carbonate compound measured by a laser diffraction method is preferably 1.1 μm or more and 12.5 μm or less, more preferably 1.5 μm or more and 12 μm or less, and even more preferably 2 μm or more and 10 μm or less, which can improve the dispersibility of the calcium carbonate compound and efficiently suppress shrinkage of the heating surface.

[0028] The average major axis of the calcium carbonate compound as observed with a scanning electron microscope is preferably 0.5 μm or more and 25 μm or less, more preferably 1 μm or more and 22 μm or less, and even more preferably 2 μm or more and 18 μm or less, which suppresses aggregation of the calcium carbonate compounds themselves or of the calcium carbonate compounds with other components, thereby enabling shrinkage of the heating surface and an increase in the back surface temperature during heating to be suppressed to higher levels.

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

[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 0.02 or more, more preferably 0.20 or more, and even more preferably 1.00 or more, which makes it possible to efficiently impart a high aspect ratio to the calcium carbonate compound and to further reduce the occurrence of warping and cracking in the inorganic molded body.

[0031] The calcium-based carbonate compound is preferably a synthetic calcium-based carbonate compound. By using a synthetic calcium-based carbonate compound, which is a reaction product of calcium hydroxide and carbon dioxide, as the calcium-based carbonate compound, it is possible to reuse carbon dioxide that is secondarily generated in the industrial process, thereby contributing to a reduction in carbon dioxide emissions throughout the industrial process. In addition, in the process of producing magnesium hydroxide from seawater, the calcium-based carbonate compound produced as a by-product in the process of removing carbonates from seawater and seawater residue containing magnesium hydroxide as its main components can also be used as a calcium-based carbonate compound source.

[0032] (Method of producing calcium carbonate compounds) The method for synthesizing calcium carbonate compounds is not particularly limited, and known production methods can be used. A typical example is the carbon dioxide method, in which carbon dioxide gas is blown into milk of lime (a slurry prepared by adding an excess of slaked lime to a saturated aqueous solution of slaked lime) to carbonate the mixture. The carbon dioxide gas used in the carbon dioxide method can be the flue gas from a lime calciner, a boiler, a waste incinerator, or the like, located near a calcium carbonate compound production plant.

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

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

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

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

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

[0038] In the seed crystal method, it is preferable to promote carbonation in the presence of a phosphate. Examples of phosphate include, but are not limited to, phosphoric acid, sodium dihydrogen phosphate anhydrous, sodium dihydrogen phosphate monohydrate, sodium dihydrogen phosphate dihydrate, disodium hydrogen phosphate dodecahydrate, potassium dihydrogen phosphate anhydrous, and ammonium dihydrogen phosphate anhydrous.

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

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

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

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

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

[0044] (hydraulic 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.

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

[0046] (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), perlite, 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.

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

[0048] (reinforcing fiber material) Examples of reinforcing fiber materials that can be used include pulps such as softwood pulp, hardwood pulp, fibrillated 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.

[0049] To improve the strength and toughness of the inorganic molded body, the content of the reinforcing fiber material is preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 26% by mass or less, and even more preferably 4% by mass or more and 22% by mass or less, based on the total amount of materials constituting the inorganic molded body. By setting the content of the reinforcing fiber material within the above range, it is possible to achieve a sufficient reinforcing effect while suppressing the protrusion of fibers from the surface of the inorganic molded body, 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 inorganic molded body, in order to improve the smoothness of the inorganic molded body.

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

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

[0052] (optional ingredient) In addition to the above materials, various materials can be blended into the inorganic molded body depending on the purpose, 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. In addition, recycled materials made by crushing scraps generated during the processing of the inorganic molded body can be appropriately added and used.

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

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

[0055] The inorganic molded body may be a concrete structure. The concrete structure is composed of a hardened body of a hydraulic composition. The hydraulic composition is composed of a powder containing, in addition to calcium carbonate, at least one of blast furnace slag, an expansive agent, slaked lime, quicklime, fly ash, and a cementitious material. As the calcium carbonate, the above-mentioned calcium carbonate compounds can be suitably used. As the cementitious material, the cementitious materials shown in the hydraulic material can be suitably used.

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

[0057] The hardened hydraulic composition is obtained by hardening a paste obtained by kneading the hydraulic composition with water. 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. [Example]

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

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

[0060] (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.

[0061] (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 placed in the beaker. The mixture was subjected to ultrasonic treatment (UD-201, manufactured by Tomy Seiko Co., Ltd.) for 3 minutes to prepare a dispersion. The volumetric D of this dispersion was measured using a laser diffraction particle size distribution analyzer (Microtrac HRA Model 9320-X100, manufactured by Nikkiso Co., Ltd.). 50 The value was measured as the average particle size (μm).

[0062] (3) 46° (aragonite) peak intensity I by XRD measurement a29° (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 crystalline material. 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.

[0063] (4) Calculation of the average major axis, average minor axis, and aspect ratio by scanning electron microscope observation Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied by tracing it with a spatula. After platinum deposition, particle images of the sample powder were taken at 2,000 magnification using a scanning electron microscope (FE-SEM: Hitachi S-4700). Figures 1 to 4 show the SEM images. Using image analysis software (Image J), ​​20 particles were randomly selected from the SEM images, and the average major and minor diameters and aspect ratios (ratios of major and minor diameters) of the primary particles were calculated. The major and minor diameters were measured as follows: For a randomly selected particle, the length of the line with the longest diameter was defined as the "major diameter," and the diameter of the line perpendicular to the major axis at the center of the line giving the major diameter (major axis) on the particle image was defined as the "minor diameter."

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

[0065] (6) Oil absorption amount Take 2.00g of sample powder and place it on a watch glass. Add dioctyl phthalate (DOP) from a burette drop by drop while kneading with a spatula. Add one drop to the solidified, coagulated sample and stop mixing when it suddenly softens. Determine the amount of oil (mL) used until final solidification, and calculate the oil absorption per 100g of sample using the following formula. A=V÷S×100 Here, A is the oil absorption (mL / 100g), V is the amount of oil used until solidification (mL), and S is the amount of sample (g).

[0066] (7) Mesopore volume Mesopore volume was measured by nitrogen adsorption. First, as a pretreatment, a BELPREP-vac II (Microtrac-Bell) was used to perform vacuum degassing at 120°C for 8 hours. Next, a BELSORP-mini II (Microtrac-Bell) was used to measure the nitrogen adsorption / desorption isotherm according to the constant volume method. The measurement conditions were as follows. Finally, mesopore volume was calculated using the BJH method. The BJH method was used to analyze pore diameters from approximately 3.4 nm to approximately 200 nm. [Measurement conditions] Adsorption temperature: 77K Saturated vapor pressure: Actual measurement Adsorbate cross section: 0.162nm 2 Adsorbate: Nitrogen Equilibration waiting time: 500 seconds*1 *1: Waiting time after reaching adsorption equilibrium (the state in which the pressure change during adsorption / desorption is below a specified value)

[0067] <Production of calcium carbonate compounds> [Example 1-1] Calcium carbonate compound (aspect ratio 10.4) A mixed slurry of 6980 g of slaked lime powder (calculated as CaO), 630 g of aragonite seed crystal powder, and 500 g of disodium hydrogen phosphate dodecahydrate was prepared by stirring a 220 L stainless steel vessel equipped with a baffle and containing 180 L of water. The mixture was then heated to 70 °C and stirred at 150 rpm using a stirrer equipped with a single turbine blade. A flue gas extraction pipe was connected to the exhaust outlet of an LNG-fueled steam production boiler. A test blower was used to draw in the flue gas. Measurements using a CO2 meter (XP-3140, manufactured by New Cosmos Electric Co., Ltd.) revealed a CO2 concentration of 10% by volume. The test blower was used to introduce flue gas into the 220 L stainless steel vessel at a rate of 100 L / min, and the reaction was carried out for 7 hours. The solid was then filtered, washed with about five times as much water as the solid content, dried at 110°C for 24 hours, and pulverized to obtain a sample powder of a calcium carbonate compound.

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

[0069] [Example 1-3] Calcium carbonate compound (aspect ratio 2.7) A sample powder of calcium carbonate compound was obtained by the same procedure as in Example 1-1, except that 7170 g of milk of lime (calculated as CaO) was prepared, aragonite seed crystals and disodium hydrogen phosphate dodecahydrate were not added, and the reaction temperature was set at 40°C.

[0070] [Comparative Example 1-1] Calcium carbonate compound (aspect ratio 1.2) A sodium carbonate solution was prepared by adding 5940 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries, Ltd.: purity 99.8%) to a 220 L stainless steel vessel equipped with a baffle and containing 100 L of water under stirring. Meanwhile, 1000 L of water was placed in a 2000 L polyethylene vessel, and 6940 g of calcium chloride reagent (manufactured by Wako Pure Chemical Industries, Ltd.: purity 95%) was added under stirring to prepare a calcium chloride solution (Ca 2+ A sample powder of a calcium carbonate compound was prepared by the same procedure as in Example 1-1, except that 100 L of the sodium carbonate aqueous solution was added all at once to the stirred calcium chloride aqueous solution, and the reaction was continued for about 30 minutes.

[0071] [Table 1]

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

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

[0074] [Production Example 1-2] Production of inorganic molded body by papermaking method An inorganic formed body was obtained in the same manner as in Production Example 1-1, except that the calcium carbonate compound of Example 1-2 was used as the calcium carbonate compound.

[0075] [Production Example 1-3] Production of inorganic molded body by papermaking method An inorganic formed body was obtained in the same manner as in Production Example 1-1, except that the calcium carbonate compound of Example 1-3 was used as the calcium carbonate compound.

[0076] [Comparative Production Example 1-1] Production of inorganic molded body by papermaking method An inorganic formed body was obtained in the same manner as in Production Example 1-1, except that the calcium carbonate compound of Comparative Example 1-1 was used as the calcium carbonate compound.

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

[0078] [Comparative Production Example 1-3] Production of inorganic molded body by papermaking method An inorganic molded body was obtained in the same manner as in Production Example 1-1, except that a calcium carbonate compound having an aspect ratio of 25 was used as the calcium carbonate compound. However, the calcium carbonate compound broke during molding and was unable to maintain its original shape, so no evaluation was performed.

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

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

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

[0082] (heating test) The heating test was carried out using the following equipment and procedure. Figure 5 is a partial perspective view that shows a schematic diagram of the heating tester. As shown in Figure 5, an electric heater was used as the heat source, and fireproof material was installed between the test specimen and the heat source to stabilize the temperature at around 900°C, and a thermocouple was used to measure the temperature on the backside of the test specimen. Specifically, an electric heater (1.2 kW heater) was used as the heat source, and a K-type thermocouple and a temperature controller were connected. Each thermocouple was also connected to a data logger. The distance between the heating surface of the test specimen and the heat source was fixed at approximately 70 mm.

[0083] The test procedure was as follows. (1) A scrap board was placed, preheated to 902°C, and then heated once. (2) The specimen was inserted after the heated surface had cooled to below 200°C. (3) A thermocouple was placed in the center of the back surface (top surface in the figure) of the test specimen, and a calcium silicate plate (approximately 30 mm x 70 mm) and a weight were placed on top and fixed in place. (4) Heating was started, and the sample was left for the specified time (45 minutes), after which the temperatures on the front and back sides were recorded with a data logger. During this time, the temperature setting of the electric heater was set to 902°C on the heating surface side, and the temperature was controlled with a temperature controller with a lower limit of 900°C. The data logger also measured the temperature every 10 seconds, and the data was recorded at this interval. (5) After the test was completed, the specimen was removed and the following items were measured (each item was also measured before the test): Dimensions: The length and width of the back surface and heating surface were measured with a vernier caliper. The area of ​​the heating surface (mm 2 ) was calculated, and the heating surface shrinkage (%) was calculated based on the following formula. Heating surface shrinkage (%) = {|S1-S0| / S0} x 100 (where S0 is the area of ​​the heated surface before the test, and S1 is the area of ​​the heated surface after the test.) Warpage: The specimen was placed on an iron surface plate, and the height of the center of each side of the specimen from the iron surface plate was measured with a thickness gauge, and the average value (mm) was calculated. This average value was taken as the warpage (mm) after heating.

[0084] [Table 2]

[0085] [Table 3]

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

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

[0088] [Production Example 2-2] Production of inorganic molded body by extrusion molding method An inorganic formed body was obtained in the same manner as in Production Example 2-1, except that the calcium carbonate compound of Example 1-2 was used as the calcium carbonate compound.

[0089] [Production Example 2-3] Production of inorganic molded body by extrusion molding method An inorganic formed body was obtained in the same manner as in Production Example 2-1, except that the calcium carbonate compound of Example 1-3 was used as the calcium carbonate compound.

[0090] [Comparative Production Example 2-1] Production of inorganic molded body by extrusion molding method An inorganic formed body was obtained in the same manner as in Production Example 2-1, except that the calcium carbonate compound of Comparative Example 1-1 was used as the calcium carbonate compound.

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

[0092] [Comparative Production Example 2-3] Production of inorganic molded body by extrusion molding method An inorganic molded body was obtained in the same manner as in Production Example 2-1, except that a calcium carbonate compound having an aspect ratio of 25 was used as the calcium carbonate compound. However, the calcium carbonate compound broke during molding and was unable to maintain its original shape, so no evaluation was performed.

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

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

[0095] (3-point bending test) The three-point bending test was carried out in accordance with JIS A 5430. The results were used to calculate the strength (N / mm 2 ) was decided.

[0096] (heating test) The measurement was carried out in the same manner as in the papermaking method.

[0097] [Table 4]

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

Claims

1. having a calcite-type crystal structure, an aragonite-type crystal structure, or a combination thereof; an aspect ratio of the average major axis to the average minor axis of the particles is 2 or more and 19 or less; Oil absorption is 40 mL / 100 g or more and 90 mL / 100 g or less Calcium carbonate compound powder for inorganic molding.

2. 2. The calcium carbonate compound powder for inorganic compacts according to claim 1, having an apparent specific gravity of 0.1 g / mL or more and 1.0 g / mL or less.

3. Mesopore volume: 0.018 cm ３ / g or more 0.045cm ３ 2. The calcium carbonate compound powder for inorganic compacts according to claim 1, wherein the calcium carbonate content is 1 / g.

4. 2. The calcium carbonate compound powder for use in inorganic compacts according to claim 1, wherein the average particle size measured by a laser diffraction method is 1.1 μm or more and 12.5 μm or less.

5. 2. The calcium carbonate compound powder for inorganic compacts according to claim 1, wherein the average major axis of the powder is 0.5 μm or more and 25 μm or less as observed with a scanning electron microscope.

6. BET specific surface area is 1 m ２ / g or more 10m ２ 2. The calcium carbonate compound powder for inorganic compacts according to claim 1, wherein the calcium carbonate content is 0.1g or less.

7. 2. The calcium carbonate compound powder for inorganic compacts according to claim 1, wherein the calcium carbonate compound powder for inorganic compacts is a synthetic calcium carbonate compound powder.

Images