Calcium carbonate compound and water-containing composition

Abstract

To provide a calcium carbonate compound and a water-containing composition capable of further reducing shrinkage of a heated surface and elevation of back surface temperature during heating when used in an inorganic molded body as a building material. A dispersion of the calcium carbonate compound dispersed in water in a concentration of 33 mass% has a viscosity of 1000-2000 cP at 30 rpm. The viscosity of a dispersion dispersed in water in a concentration of 33 mass% is preferably 1000-2500 cP at 6 rpm. The ratio μ6 / μ30 of the viscosity μ6 of a dispersion dispersed in water in a concentration of 33 mass% at 6 rpm to the viscosity μ30 at 30 rpm is preferably 1.0-2.5.

Description

Calcium-based carbonate compound and water-containing composition

[0001] The present invention relates to a calcium carbonate compound and a water-containing composition.

[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 for promoting 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 a calcareous material (Japanese Patent Laid-Open Publication No. 2012-116685).

[0005] JP 2012-116685 A

[0006] However, even with the above techniques, shrinkage of the heated surface and an increase in the temperature of the back surface may occur during heating, and there is a demand for further improvement in the fire resistance of inorganic molded bodies 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 and a water-containing composition that can exhibit a higher level of fire resistance when used in an inorganic molded body as a building material.

[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 relates to a calcium carbonate compound having a viscosity of 1000 cP or more and 2000 cP or less at 30 rpm when dispersed in water at a concentration of 33% by mass.

[0011] The calcium carbonate compound has a viscosity at 30 rpm of a dispersion in a predetermined concentration within a specific range, and therefore, when used in an inorganic molded body, it can exhibit a higher level of fire resistance. Although the reason for this is unclear, it is presumed as follows.

[0012] The inventors have conducted further research into applying the dispersion of calcium carbonate compounds obtained in the manufacturing process of synthetic calcium carbonate compounds directly to the manufacturing process of inorganic molded bodies, and have found that if the dispersion has the above-mentioned specific viscosity, it is possible to suppress the shrinkage of the heating surface and the increase in the back surface temperature during heating.

[0013] The dispersion liquid in which the calcium carbonate compound is dispersed has a relatively high viscosity within a specific range. This is presumably due to the reduced aggregation of the calcium carbonate compound, resulting in a high degree of dispersion in the form of primary particles. By directly incorporating the dispersion liquid containing the calcium carbonate compound in the form of primary particles during the production of an inorganic molded body, the calcium carbonate compound is uniformly dispersed in the form of primary particles in the inorganic molded body. As a result, the calcium carbonate compound functions as a so-called reinforcing material, thereby suppressing shrinkage of the heated surface. Furthermore, the uniform dispersion of the low-thermal-conductivity calcium carbonate compound improves the insulation properties of the inorganic molded body in the thickness direction, thereby suppressing an increase in the back surface temperature.

[0014] It is believed that these combined effects enable the shrinkage of the heated surface and the rise in temperature of the back surface during heating to be suppressed to a higher degree, allowing the inorganic molded body as a whole to exhibit a high level of fire resistance.

[0015] 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 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.

[0016] In one embodiment, the viscosity of a dispersion of the calcium carbonate compound dispersed in water at a concentration of 33% by mass at 6 rpm is preferably 1000 cP or more and 2500 cP or less, which improves the uniformity of the dispersion of the calcium carbonate compound and enables higher levels of suppression of shrinkage of the heating surface and increase in temperature of the back surface during heating.

[0017] In one embodiment, the viscosity μ of a dispersion liquid in which the calcium carbonate compound is dispersed in water at a concentration of 33% by mass is ６ Viscosity μ at 30 rpm ３０ Ratio to μ ６ / μ ３０ is preferably 1.0 or more and 2.5 or less. This reduces the thixotropy of the dispersion, and the viscosity at both high and low stirring speeds or shear forces does not deviate significantly, maintaining a certain level of high viscosity. As a result, deformation and deterioration of the molded body when force is applied and released during molding, pressing, etc. in the inorganic molded body production process are suppressed, and an inorganic molded body having excellent fire resistance can be produced.

[0018] In one embodiment, the aspect ratio of the average major axis to the average minor axis of the calcium carbonate compound is preferably 2 or more and 19 or less. In one embodiment, the average particle size of the calcium carbonate compound measured by laser diffraction method is preferably 1.1 μm or more and 12.5 μm or less. In one embodiment, the average major axis of the calcium carbonate compound measured by observation with a scanning electron microscope is preferably 0.5 μm or more and 25 μm or less. By satisfying one or a combination of these configurations, it is possible to suitably impart a viscosity within a specific range to the dispersion of the calcium carbonate compound.

[0019] In another embodiment, the present invention relates to a water-containing composition containing water and the calcium-based carbonate compound.

[0020] The water-containing composition can have a viscosity within the above-mentioned range, and therefore can maintain a high degree of primary particle state of the calcium carbonate compound. Therefore, when the water-containing composition is applied to the production of an inorganic molded body, the resulting inorganic molded body can be highly suppressed from shrinking on the heated surface and from increasing in temperature on the back surface during heating.

[0021] In one embodiment, the water content of the water-containing composition may be 40% by mass or more and 99% by mass or less, which allows the water-containing composition to take the form of a so-called slurry.

[0022] In one embodiment, the water content of the water-containing composition may be 5% by mass or more and 60% by mass or less, which allows the water-containing composition to take the form of a so-called cake.

[0023] In one embodiment, the hydrous composition is preferably obtained without drying in the production process of the synthetic calcium carbonate compound. By using a synthetic calcium carbonate compound that is a reaction product of calcium hydroxide and carbon dioxide as the calcium carbonate compound, carbon dioxide generated secondarily in the industrial process can be reused, which can contribute to reducing carbon dioxide emissions throughout the industrial process. Furthermore, since the hydrous composition is obtained without drying, it is possible to further reduce carbon dioxide emissions.

[0024] In yet another embodiment, the present invention relates to an inorganic molding comprising the calcium-based carbonate compound.

[0025] The inorganic formed body contains the calcium carbonate compound, and therefore can exhibit a higher level of fire resistance.

[0026] In still another embodiment, the present invention relates to a method for producing an inorganic molded body, the method including a step of molding an inorganic composition containing the water-containing composition.

[0027] In this production method, the water-containing composition is subjected to the molding step as it is, so that an inorganic molded article having excellent fire resistance can be efficiently produced.

[0028] 1 is a SEM photograph of a calcium carbonate compound obtained from the water-containing composition of Example 1-1 of the present invention. 2 is a SEM photograph of a calcium carbonate compound obtained from the water-containing composition of Example 1-2 of the present invention. 3 is a partial perspective view schematically showing a heating tester.

[0029] The calcium carbonate compound and water-containing composition according to one embodiment of the present invention will be described below, but the present invention is not limited to these embodiments.

[0030] <Calcium-Based Carbonate Compound> The calcium-based carbonate compound according to this embodiment is a calcium-based carbonate compound having a viscosity at 30 rpm of 1000 cP or more and 2000 cP or less when dispersed in water at a concentration of 33% by mass. The viscosity at 30 rpm is preferably 1100 cP or more and 1900 cP or less, and more preferably 1200 cP or more and 1800 cP or less. This improves workability and allows the degree of primary particle state of the calcium-based carbonate compound to be maintained at a high level. When the dispersion is used to produce an inorganic molded body, shrinkage of the heated surface and increase in back surface temperature during heating can be reduced.

[0031] The viscosity at 6 rpm of a dispersion in which the calcium carbonate compound is dispersed in water at a concentration of 33% by mass is 1000 cP or more and 2500 cP or less. The viscosity at 6 rpm is preferably 1100 cP or more and 2400 cP or less, and more preferably 1200 cP or more and 2300 cP or less. This improves the uniformity of the dispersion of the calcium carbonate compound. When the dispersion is used to produce an inorganic molded body, shrinkage of the heated surface and an increase in the back surface temperature during heating can be suppressed to a higher level.

[0032] The viscosity μ of the dispersion liquid in which the calcium carbonate compound is dispersed in water at a concentration of 33% by mass at 6 rpm ６ Viscosity μ at 30 rpm ３０ Ratio to μ ６ / μ ３０ The ratio μ is 1.0 or more and 2.5 or less. ６ / μ ３０ is preferably 1.0 or more and 2.2 or less, and more preferably 1.0 or more and 1.8 or less, whereby the occurrence of thixotropy in the dispersion state can be suppressed, and deformation and deterioration of the molded body when force is applied and released in the inorganic molded body production process can be prevented.

[0033] 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 an aspect ratio as described below, it is preferable that the calcium carbonate compound contains at least an aragonite type crystal structure.

[0034] The aspect ratio of the average major axis to the average minor axis of the calcium carbonate compound is preferably 2 or more and 19 or less, more preferably 2.5 or more and 17 or less, and even more preferably 3 or more and 15 or less. By setting the aspect ratio of the calcium carbonate compound within the above range, the dispersion of the calcium carbonate compound can preferably have a viscosity within the above range. Furthermore, since a calcium carbonate compound with a high aspect ratio effectively functions as a reinforcing material, shrinkage of the heated surface and an increase in the back surface temperature are suppressed, and the inorganic molded body as a whole can exhibit excellent fire resistance.

[0035] When the inorganic molded body is produced by a papermaking method, the aspect ratio of the calcium carbonate compound is preferably 4 to 19, more preferably 6 to 18, and even more preferably 8 to 17. When the inorganic molded body is produced by an extrusion molding method, the aspect ratio of the calcium carbonate compound is preferably 2 to 12, more preferably 2.5 to 10, and even more preferably 3 to 8.

[0036] 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. This allows the dispersion of the calcium carbonate compound to have a suitable viscosity within the above range. Furthermore, the dispersibility of the calcium carbonate compound can be improved, and shrinkage of the heating surface can be efficiently suppressed.

[0037] 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. This allows the calcium carbonate compound dispersion to have a suitable viscosity within the above range. Furthermore, aggregation of the calcium carbonate compounds with each other or between the calcium carbonate compound and other components is suppressed, thereby enabling shrinkage of the heating surface and an increase in the back surface temperature during heating to be suppressed to a higher level.

[0038] 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 to a higher level the shrinkage of the heating surface and the rise in the temperature of the back surface during heating.

[0039] In the X-ray diffraction measurement of the calcium carbonate compound, the peak intensity I of aragonite 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. This allows a high aspect ratio to be efficiently imparted to the calcium carbonate compound, and the viscosity of the dispersion can be appropriately controlled. In addition, the fire resistance of the inorganic molded body can be improved to a higher level.

[0040] The calcium-based carbonate compound is preferably a synthetic calcium-based carbonate compound. By using a synthetic calcium-based carbonate compound that is a reaction product of calcium hydroxide and carbon dioxide as the calcium-based carbonate compound, carbon dioxide that is secondarily generated in the industrial process can be reused, 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 that is by-produced 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.

[0041] <Water-Containing Composition> The water-containing composition according to this embodiment contains water and the calcium carbonate compound. Since the water-containing composition contains the calcium carbonate compound having the above-described structure, it can have a viscosity within the specific range.

[0042] The water content of the water-containing composition may be 40% by mass or more and 99% by mass or less, 50% by mass or more and 99% by mass or less, or 60% by mass or more and 99% by mass or less, whereby the water-containing composition can take the form of a so-called slurry.

[0043] The water content of the water-containing composition may be 5% by mass or more and 60% by mass or less, 10% by mass or more and 60% by mass or less, or 15% by mass or more and 60% by mass or less, thereby allowing the water-containing composition to take the form of a so-called cake.

[0044] The method for measuring the water content of the water-containing composition is as described in the Examples.

[0045] The hydrous composition is preferably obtained without drying in the production process of the synthetic calcium carbonate compound (described later). By using a synthetic calcium carbonate compound that is a reaction product of calcium hydroxide and carbon dioxide as the calcium carbonate compound, carbon dioxide generated secondarily in the industrial process can be reused, which contributes to reducing carbon dioxide emissions throughout the industrial process. Furthermore, since the hydrous composition is obtained without drying, it is possible to further reduce carbon dioxide emissions.

[0046] The water-containing composition may contain, in addition to the calcium carbonate compound, known optional components such as surfactants, viscosity modifiers, other metals or metal salts, acids, and alkalis.

[0047] <Method for producing calcium carbonate compound and method for producing hydrous composition> The method for synthesizing a calcium carbonate compound is not particularly limited, and known production methods can be used. Typically, a carbon dioxide gas method is preferred in which carbon dioxide gas is blown into milk of lime (a slurry in which excess slaked lime is added to a saturated aqueous solution of slaked lime) to carbonate it. The carbon dioxide gas used in the carbon dioxide gas method can be exhaust gas from the flue of a lime calciner installed near a calcium carbonate compound production plant, or exhaust gas from a boiler, a waste incinerator, or the like.

[0048] 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.

[0049] 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 a "seed crystal method") in which needle-shaped synthetic calcium carbonate compound having an aragonite-type crystal structure is used as seed crystals in a slaked lime slurry, carbon dioxide gas is introduced into the slurry, and the seed crystals are grown to a desired particle size by a carbonation reaction.

[0050] In the seed crystal method, the amount of the seed crystals to be added is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 5 parts by mass or more and 20 parts by mass or less, and even more preferably 8 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of slaked lime (calculated as CaO).

[0051] In the seed crystallization method, the concentration of carbon dioxide gas varies depending on the type of exhaust gas generated from each combustion engine, but is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 10% by volume or more, when carbonation efficiency is taken into consideration. The flow rate of carbon dioxide gas is preferably 10 L / min to 200 L / min, more preferably 30 L / min to 150 L / min, and even more preferably 60 L / min to 120 L / min, per 10 kg of the charged raw material CaO, when carbonation efficiency and production capacity are taken into consideration.

[0052] In the seed crystallization method, the carbonation temperature (the temperature of the slaked lime slurry) 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.

[0053] In the seed crystal method, it is preferable to allow carbonation to proceed in the presence of a phosphate. The phosphate is not particularly limited, but examples thereof include phosphoric acid, sodium dihydrogen phosphate anhydrous, sodium dihydrogen phosphate monohydrate, sodium dihydrogen phosphate dihydrate, disodium hydrogen phosphate dodecahydrate, potassium dihydrogen phosphate anhydrous, and ammonium dihydrogen phosphate anhydrous.

[0054] 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, relative to 100 parts by mass of slaked lime (calculated as CaO).

[0055] If a high aspect ratio is not required, a calcium carbonate compound can also be produced without adding seed crystals or phosphate.

[0056] By the above procedure, a calcium carbonate compound in the form of a dispersion can be produced. In addition, a water-containing composition can be obtained by using the dispersion containing the calcium carbonate compound in the form of a slurry or cake without drying.

[0057] The water content of the obtained water-containing composition may be adjusted by adding water to the water-containing composition, filtering or pressing the water-containing composition to remove water, or by combining these methods.

[0058] In addition to the carbon dioxide gas method, a waste seawater utilization method is also preferred from the viewpoint of waste utilization and carbon dioxide reduction, in which an alkaline agent such as magnesium hydroxide is added to waste seawater (residue after removing magnesium) generated when magnesium hydroxide is produced by adding slaked lime or the like to seawater, and carbon dioxide gas is then blown into the waste seawater. Furthermore, as described above, in the process of producing magnesium hydroxide from seawater, calcium 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 a calcium carbonate compound source. The water-containing compositions obtained by these methods may be washed with water or the water content may be adjusted as described above.

[0059] <Uses of calcium-based carbonate compound and water-containing composition> The uses of the calcium-based carbonate compound and water-containing composition are not particularly limited. For example, they are suitable as functional agents for inorganic molded bodies, such as building materials, fillers for resins, etc. Hereinafter, embodiments in which the calcium-based carbonate compound and water-containing composition are used for inorganic molded bodies will be described.

[0060] The inorganic molded body is preferably formed from an inorganic composition containing a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium carbonate compound.

[0061] (Hydraulic Materials) Examples of hydraulic materials include cementitious materials, gypsum, lime, slag, etc. Examples of cementitious materials include commonly used cements, such as ordinary Portland cement, high-early-strength cement, moderate-heat cement, fly ash cement, blast furnace slag cement, and alumina cement. Examples of gypsum include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. Examples of slag include blast furnace slag and converter slag. These hydraulic materials can be used alone or in combination of two or more.

[0062] The content of the hydraulic material is preferably 5% by mass or more and 45% by mass or less, more preferably 8% by mass or more and 42% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total amount of materials constituting the inorganic molded body. By setting the content of the hydraulic material within the above range, it is possible to improve the physical properties of the inorganic molded body, such as bending strength and peel strength, and to suppress an increase in the bulk specific gravity of the inorganic molded body, thereby improving workability during construction.

[0063] (Silicate Material) Examples of siliceous materials include silica sand, silica powder, silica fume, fly ash, diatomaceous earth, layered silicates (e.g., mica, talc, kaolin, bentonite), perlite, wollastonite, lightweight aggregates (e.g., fly ash balloons, perlite, shirasu balloons, glass foams, etc.), and other SiO ２ These siliceous materials can be used alone or in combination of two or more. Talc, mica, and wollastonite can also be used as reinforcing fiber materials, which will be described later.

[0064] The content of the siliceous material is preferably 10% by mass or more and 55% by mass or less, more preferably 12% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less, based on the total amount of materials constituting the inorganic molded body. If the content of the siliceous material is within the above range, it becomes possible to set the bending strength, bulk specific gravity, water absorption rate, dimensional stability, etc. of the inorganic molded body within the desired range. In addition, as the siliceous material, perlite, fly ash balloons, shirasu balloons, etc., having a unit volume mass of 0.5 g / cm 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.

[0065] (Reinforcing Fiber Material) Examples of reinforcing fiber materials that can be used include pulps such as softwood pulp, hardwood pulp, fibrillated pulp thereof, and pulp obtained by defibrating waste paper, organic reinforcing fiber materials such as vinylon fiber, acrylonitrile fiber, and polypropylene fiber, and inorganic reinforcing fiber materials such as rock wool and glass fiber. These reinforcing fiber materials can be used alone or in combination of two or more.

[0066] In order to improve the strength and toughness of the inorganic molded body, the content of the reinforcing fiber material is preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 26% by mass or less, and even more preferably 4% by mass or more and 22% by mass or less, based on the total amount of materials constituting the inorganic molded body. By setting the content of the reinforcing fiber material within the above range, it is possible to exhibit a sufficient reinforcing effect while suppressing the protrusion of fibers on the surface of the inorganic molded body, thereby improving smoothness. When an inorganic reinforcing fiber material having an average length of 1 mm to 50 mm is blended as a reinforcing fiber material, in order to improve the smoothness of the inorganic molded body, it is preferable to use other reinforcing fiber materials in combination so that the content is 10% by mass or less, based on the total amount of materials constituting the inorganic molded body.

[0067] (Calcium-Based Carbonate Compound) As the calcium-based carbonate compound, the above-mentioned calcium-based carbonate compound that has not been dried can be suitably used. That is, it is preferable to use the calcium-based carbonate compound in the form of an undried water-containing composition for producing an inorganic molded body.

[0068] The content (solid 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 conductive calcium carbonate compound in a content within the above range, the heat insulating properties in the thickness direction of the inorganic molded body are improved, and the rise in the back surface temperature can be suppressed to a high level.

[0069] (Optional Components) In addition to the above-mentioned materials, various materials such as hollow resin bodies, wood chips, wood flour, resin powder, antifoaming agents, flocculants, water repellents, thickeners (methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.), dispersants, etc. can be blended into the inorganic molded body depending on the purpose in order to impart various functions. It is also possible to appropriately add recycled materials obtained by crushing scraps generated during processing of the inorganic molded body.

[0070] (Method for manufacturing inorganic molded body) The method for manufacturing the inorganic molded body according to this embodiment is not particularly limited and includes a step of molding an inorganic composition containing the hydrous composition. Examples of molding methods that can be used include commonly used papermaking, extrusion molding, flow-on molding, casting molding, and press (compression) molding. The inorganic molded body can be obtained by subjecting a green sheet molded by these methods to a dehydration step such as press dehydration and / or a patterning step such as embossing, followed by a curing step such as room temperature curing, steam curing, or autoclave curing. A drying step may then be performed, followed by a shaping step or a painting step, as necessary.

[0071] (Uses of inorganic molded body) The uses of the inorganic molded body are not particularly limited, and it can be suitably used as a performance maintaining material such as a wall material, a floor material, a roofing material, various boards, external decorative members, interior and exterior finishing materials such as building materials, sealing materials, heat insulating materials, sound absorbing materials, waterproofing materials, etc. The inorganic molded body is preferably a cement-based molded body containing a cementitious material, and more preferably a calcium silicate molded body. Among them, the molded body is more preferably a molded board.

[0072] 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.

[0073] <Evaluation of calcium-based carbonate compounds> The water-containing compositions and calcium-based carbonate compounds obtained in the examples and comparative examples were analyzed as follows. The results of each analysis are shown in Table 1 and Figures 1 and 2. In Table 1, arrows indicate results that are the same as those in the left column.

[0074] (1) BET Specific Surface Area A sample powder was pretreated in a nitrogen gas atmosphere at about 130°C for about 30 minutes using an 8-tube preheat unit (manufactured by MOUNTECH Co., Ltd.), and the BET specific surface area (m ２ / g) was measured. Note that, in order to measure the BET specific surface area, it is necessary to measure the sample in a dried powder form. Therefore, in the case of a sample cake or sample slurry, these were dried at 110°C for 24 hours to prepare a sample powder for BET specific surface area measurement.

[0075] (2) Average particle size by laser diffraction method 50 mL of ethanol was placed in a 100 mL beaker, and about 0.3 g of the sample cake, about 0.6 mL of the sample slurry, or about 0.2 g of the sample powder was placed in the 100 mL beaker. The mixture was subjected to ultrasonic treatment (UD-201, manufactured by Tomy Seiko Co., Ltd.) for 3 minutes to prepare a dispersion. The volume-based 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 diameter (μm).

[0076] (3) Calculation of Average Long Diameter, Average Short Diameter, and Aspect Ratio by Scanning Electron Microscopy. Double-sided tape was attached to an aluminum sample stage, and the sample powder was applied by tracing it with a spatula. After platinum deposition, particle images of the sample powder were photographed at 2,000 magnifications using a scanning electron microscope (FE-SEM: S-4700, manufactured by Hitachi, Ltd.). SEM images are shown in Figures 1 and 2. Figure 1 is an SEM image of the calcium carbonate compound obtained from the hydrous composition of Example 1-1. Figure 2 is an SEM image of the calcium carbonate compound obtained from the hydrous composition of Example 1-2. Using image analysis software (Image J), ​​20 particles were randomly selected from the SEM images, and the average long diameter, short diameter, and aspect ratio (ratio of long diameter to short diameter) of the primary particles were calculated. Note that, for observation using a scanning electron microscope, the sample powder must be dried and in powder form. Therefore, in the case of sample cakes or sample slurries, they were dried at 110°C for 24 hours to prepare sample powders for observation under a scanning electron microscope.

[0077] (4) 46° (aragonite) peak intensity I by XRD measurement ａ 29° (calcite) peak intensity I ｃ The sample powder was pressed and fixed onto a predetermined sample stage with a spatula, and then measured using an XRD device (MiniFlex600-C manufactured by Rigaku Corporation) to perform an identification analysis as a crystalline substance. Note that, at a 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 determined. In order to measure XRD, it is necessary to measure the sample in a dried powder form. Therefore, in the case of sample cakes or sample slurries, these were dried at 110°C for 24 hours to prepare sample powders for XRD measurement.

[0078] (5) Dynamic viscosity, static viscosity, and thixotropy value The dynamic viscosity, static viscosity, and thixotropy value of the slurry prepared to a predetermined concentration were measured. That is, the viscosity (dynamic viscosity) at a rotor rotation speed of 30 rpm and the viscosity (static viscosity) at 6 rpm were measured using a B-type viscometer. The thixotropy value was calculated by multiplying the viscosity μ at 6 rpm by the viscosity μ ６ Viscosity μ at 30 rpm ３０ The value obtained by dividing by (μ ６ / μ ３０ ) was calculated.

[0079] <Production of a hydrous composition containing a calcium-based carbonate compound> [Example 1-1] Calcium-based carbonate compound (aspect ratio 10.4) 6,980 g of slaked lime powder (calculated as CaO), 630 g of aragonite seed crystal powder, and 500 g of disodium hydrogen phosphate dodecahydrate were prepared and each was charged with stirring into a 220 L SUS vessel equipped with a baffle and pre-filled with 180 L of water to prepare a mixed slurry of the raw materials. The mixture was then heated to 70°C and stirred at that temperature using a stirrer equipped with one turbine blade at a rotation speed of 150 rpm. A flue gas extraction pipe was connected to the exhaust outlet of an LNG-fueled steam production boiler, and a test blower was used to draw in the exhaust gas. ２ When measured using a concentration meter (XP-3140 manufactured by New Cosmos Electric Co., Ltd.), CO ２ The concentration was 10% by volume. The exhaust gas was introduced into the aforementioned 220 L SUS vessel using a test blower at a rate of 100 L / min, and a carbonation reaction was carried out for 7 hours. After that, the mixture was filtered with a test filter press, washed with about 5 times the amount of water relative to the solid content, and the CaCO ３ A sample cake with a concentration of 75% by mass was obtained. A portion of the sample cake was taken out for evaluation of calcium carbonate, and the sample cake was used for evaluation without drying. The sample cake was also emulsified in water to obtain CaCO 3 . ３ A sample slurry of calcium carbonate with a concentration of 33% by mass was prepared.

[0080] Example 1-2 Calcium-Based Carbonate Compound (Aspect Ratio 2.7) A sample cake and a sample slurry of a calcium-based carbonate compound were obtained by the same procedure as in Example 1-1, except that 7,170 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 to 40°C.

[0081] [Comparative Example 1-1] Calcium carbonate compound (aspect ratio 10.4) The same operations as in Example 1-1 were carried out up to the carbonation reaction. Thereafter, the mixture was filtered using a test filter press, washed, dried at 110°C for 24 hours, and pulverized to obtain a calcium carbonate powder sample.

[0082] [Comparative Example 1-2] Calcium carbonate compound (aspect ratio 2.7) The same operations as in Example 1-2 were carried out up to the carbonation reaction. Thereafter, the mixture was filtered using a test filter press, washed, dried at 110°C for 24 hours, and pulverized to obtain a calcium carbonate powder sample.

[0083] *In Table 1, "←" indicates that the value is the same as the value in the left column.

[0084] <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.

[0085] [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 and mixed to obtain a raw material slurry. ３A calcium carbonate compound (33% by mass in concentration) was used in the amount shown in Table 2. The raw material slurry was divided and charged into a filter lined with felt, and a laminate (long side 28 mm x short side 24 mm x thickness 14 mm) was produced while suction filtering was performed using a vacuum pump. The laminate was removed from the filter and subjected to dehydration pressing. The thickness after pressing was 13 mm. After autoclave curing (curing pressure (gauge pressure) 9 kgf; curing time 12 hours), the pressed body was dried in a dryer (105°C) for 24 hours. Both sides were sanded with a sander to adjust the thickness to 12 mm, and an inorganic molded body was obtained.

[0086] [Production Example 1-2] Production of inorganic molded body by papermaking method The sample slurry of Example 1-2 (CaCO ３ An inorganic molded body was obtained in the same manner as in Production Example 1-1, except that a concentration of 33% by mass was used.

[0087] Comparative Production Example 1-1 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 sample powder of Comparative Example 1-1 was used as the calcium carbonate compound.

[0088] 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 sample powder of Comparative Example 1-2 was used as the calcium carbonate compound.

[0089] <Evaluation of Inorganic Molded Articles> The inorganic molded articles produced by the papermaking method in the Production Examples and Comparative Production Examples were evaluated as follows. The results are shown in Tables 2 and 3.

[0090] (Bulk Density) The bulk density was measured in accordance with JIS A 5430.

[0091] (Heating Test) The heating test was performed using the following equipment and procedure. Figure 5 is a partial perspective view showing a schematic diagram of the heating tester. As shown in Figure 5, an electric heater was used as the heat source, and a refractory material was installed between the test specimen and the heat source to stabilize the temperature at around 900 °C, and the temperature of the backside of the test specimen was measured with a thermocouple. Specifically, an electric heater (1.2 kW heater) was used as the heat source equipment, 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.

[0092] The test procedure was as follows: (1) A scrap board was placed, and preheating was performed up to 902°C, followed by heating once. (2) After the temperature of the heated surface had dropped below 200°C, the test specimen was inserted. (3) A thermocouple was placed in the center of the back surface (top surface in the figure) of the test specimen, and a calcium silicate board (approximately 30 mm x 70 mm) and a weight were placed on top to secure it in place. (4) Heating was initiated, and the specimen was left for a predetermined time (45 minutes), and the temperatures of the front and back surfaces were recorded with a data logger. During this time, the temperature of the electric heater was set to 902°C on the heated surface side, and was controlled by a temperature controller with a lower limit of 900°C. The data logger also measured the temperature every 10 seconds, and data was recorded at this interval. (5) After the test was completed, the test specimen was removed and the following items were measured (each item was also measured before the test). - Dimensions: The length and width of the back surface and heated surface were measured with vernier calipers. The area of ​​the heated surface (mm ２ ) was calculated, and the heated surface shrinkage (%) was calculated based on the following formula: Heating surface shrinkage (%) = {|S １ -S ０ | / S ０}×100 (in the formula, S ０ is the area of ​​the heating surface before the test, and S １ is the area of ​​the heated surface after the test.)

[0093]

[0094] The inorganic molded body of the manufacturing example was superior to the comparative manufacturing example in both the heated surface shrinkage and the back surface temperature rise. Furthermore, the inorganic molded body of the manufacturing example had a strength sufficient for practical use and did not develop cracks after heating (not shown).

[0095] [Production Example 2-1] Production of inorganic molded body by extrusion molding The materials shown in Table 3 below were charged into an omnimixer and the raw materials were dry-mixed for 3 minutes. ３ A calcium carbonate compound (75% by mass in concentration) was used to obtain the amount of calcium carbonate compound shown in Table 2. 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 a thickness of 12 mm, producing an inorganic molded body.

[0096] [Production Example 2-2] Production of inorganic molded body by extrusion molding Sample cake (CaCO ) from Example 1-2 was used as a calcium carbonate compound. ３ An inorganic molded body was obtained in the same manner as in Production Example 2-1, except that a concentration of 75% by mass was used.

[0097] Comparative Production Example 2-1 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 sample powder of Comparative Example 1-1 was used as the calcium carbonate compound.

[0098] Comparative Production Example 2-2: Production of inorganic molded body by extrusion molding. An inorganic molded body was obtained in the same manner as in Production Example 2-1, except that the sample powder of Comparative Example 1-2 was used as the calcium carbonate compound.

[0099] <Evaluation of Inorganic Molded Articles> The inorganic molded articles produced by extrusion molding in the Production Examples and Comparative Production Examples were evaluated as follows. The results are shown in Table 3.

[0100] (Bulk Density) The bulk density was measured in accordance with JIS A 5430.

[0101] (Heating test) Measurement was carried out in the same manner as in the papermaking method.

[0102]

[0103] 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 had sufficient strength for practical use and did not develop cracks after heating (not shown).

Claims

1. A calcium carbonate compound having a viscosity of 1000 cP or more and 2000 cP or less at 30 rpm when dispersed in water at a concentration of 33% by mass.

2. A calcium carbonate compound according to claim 1, in which the viscosity of the dispersion at 6 rpm when dispersed in water at a concentration of 33% by mass is 1000 cP or more and 2500 cP or less.

3. Viscosity μ of the dispersion at 6 rpm when dispersed in water at a concentration of 33% by mass ６ Viscosity μ at 30 rpm ３０ Ratio to μ ６ / μ ３０ The calcium carbonate compound according to claim 2, wherein the calcium carbonate content is 1.0 or more and 2.5 or less.

4. A calcium carbonate compound according to claim 1, having an aspect ratio of the average major axis to the average minor axis of 2 or more and 19 or less.

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

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

7. A water-containing composition comprising water and the calcium carbonate compound according to any one of claims 1 to 6.

8. The water-containing composition according to claim 7, having a water content of 40% by mass or more and 99% by mass or less.

9. The water-containing composition according to claim 7, having a water content of 5% by mass or more and 60% by mass or less.

10. The water-containing composition according to claim 7, which is obtained without drying in the production process of the synthetic calcium carbonate compound.

11. An inorganic molding comprising the calcium carbonate compound according to any one of claims 1 to 6.

12. A method for producing an inorganic molded product, comprising the step of molding an inorganic composition containing the water-containing composition according to any one of claims 7 to 10.

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