Calcium-based carbonate compound, composition, molded plate, inorganic molded body, and method for producing calcium-based carbonate compound

Abstract

The present invention provides a calcium carbonate compound, a composition, a molded plate, an inorganic molded body, and a method for manufacturing a calcium carbonate compound, which are excellent in workability during the manufacturing process. [Solution] A calcium carbonate compound in which the average particle diameter D2 of secondary particles measured by laser diffraction method is agglomerated particles of 1 μm or more and 10 μm or less, the acid-soluble silica content is 0.1 mass% or more, and the sedimentation volume is 50 mL or less.

Description

[Technical Field]

[0001] The present invention relates to a calcium carbonate compound, a composition, a molded plate, an inorganic molded body, and a method for producing a calcium carbonate compound. [Background technology]

[0002] In recent years, there has been growing interest in environmental awareness, including issues such as global warming, and calls for reducing carbon dioxide emissions into the atmosphere. In response, attempts are being made to reuse by-products and by-produced energy, such as waste, exhaust gases such as carbon dioxide, and waste heat, generated at industrial facilities such as incinerators, steel mills, and cement plants.

[0003] For example, waste concrete is discarded in huge quantities, and therefore there is a demand for its reuse from the viewpoints of saving natural resources, protecting the environment, and making effective use of resources.

[0004] The concrete waste is a waste material containing calcium, and a technique has been proposed for producing calcium carbonate by carbonating the waste material with carbon dioxide (see Patent Document 1).

[0005] Furthermore, inorganic molded products obtained using calcium carbonate are widely used for exterior wall materials for houses, etc., roof underlayment materials, eaves ceiling materials, etc., and a technique for blending acicular calcium carbonate has been proposed as a technique for increasing strength, which is one of the important properties required of inorganic molded products (see Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-69860 [Patent Document 2] Patent No. 6898926 Summary of the Invention [Problem to be solved by the invention]

[0007] However, even with the above-mentioned techniques, the strength of the inorganic molded body obtained may be reduced, and there is a risk that the workability of the entire manufacturing process may be reduced, for example, the fluidity of the mixture of raw materials may be reduced or the dispersibility of calcium carbonate in the mixture may be reduced during the manufacturing process of the inorganic molded body.

[0008] Therefore, an object of the present invention is to provide a calcium carbonate compound, a composition, an inorganic molded body, a molded plate, and a method for producing a calcium carbonate compound, which are excellent in workability during the production process. The workability includes filterability, extrudability, washability, moldability, etc. [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] That is, the present invention relates to a calcium carbonate compound in which the average particle diameter D2 of the secondary particles measured by a laser diffraction method is 1 μm or more and 10 μm or less, the content of acid-soluble silica is 0.1 mass% or more, and the sedimentation volume is 50 mL or less.

[0011] The calcium carbonate compound of the present invention preferably contains 70% by mass or more of calcium carbonate.

[0012] The calcium carbonate compound of the present invention preferably has a crystal structure of at least one selected from the group consisting of a calcite type, an aragonite type, and a vaterite type.

[0013] In the calcium carbonate compound of the present invention, the aggregated particles are preferably aggregates of primary particles, and the primary particles preferably have an average major diameter D1 of 0.1 μm or more and 5 μm or less in an SEM image.

[0014] In the calcium carbonate compound of the present invention, it is preferable that the ratio (D1 / D2) be 0.01 or more and 0.7 or less, where D1 is the average major diameter of the primary particles as measured in an SEM image and D2 is the average particle diameter of the secondary particles of the aggregated particles as measured by laser diffraction method.

[0015] The calcium carbonate compound of the present invention preferably has a viscosity (10% viscosity) of 20 cP or less when dispersed in water at a concentration of 10% by mass.

[0016] In the calcium carbonate compound of the present invention, the aspect ratio (D1 / D3) of the average major axis D1 in an SEM image of the primary particles to the average minor axis D3 in an SEM image of the primary particles is preferably 1.5 or more and 6 or less.

[0017] The calcium carbonate compound of the present invention preferably has an oil absorption of 40 mL / 100 g or more and 100 mL / 100 g or less.

[0018] The present invention relates to a composition comprising the calcium carbonate compound.

[0019] The composition of the present invention preferably further contains a resin.

[0020] The composition of the present invention preferably has a P funnel flow time of 15 seconds or less.

[0021] The composition of the present invention is preferably for use in inorganic molded articles.

[0022] The present invention relates to an inorganic formed body containing the calcium carbonate compound.

[0023] The present invention relates to a molded plate obtained by pressing a molded article of the composition, which has a surface change rate of 120% or less.

[0024] The present invention relates to a method for producing a calcium-based carbonate compound, which includes a preparation step of preparing a CaO-containing composition, a pretreatment step of mixing a silicon-containing compound containing acid-soluble silica with the CaO-containing composition to prepare a slurry, and a carbonation step of contacting the CaO-containing composition with carbon dioxide.

[0025] The method for producing a calcium carbonate compound of the present invention preferably includes a sieving step as the preparation step.

[0026] The method for producing a calcium carbonate compound of the present invention preferably includes a grinding step as the preparation step. [Effects of the Invention]

[0027] INDUSTRIAL APPLICABILITY The present invention is useful in that it can provide a calcium-based carbonate compound, a composition, a molded plate, an inorganic molded body, and a method for producing a calcium-based carbonate compound that are easy to work with in the production process. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is an SEM photograph of the calcium carbonate compound of Example 1 of the present invention. [Figure 2] 1 is an SEM photograph of a calcium carbonate compound according to Example 2 of the present invention. [Figure 3] 1 is an SEM photograph of a calcium carbonate compound according to Example 3 of the present invention. [Figure 4] 1 is an SEM photograph of a calcium carbonate compound of Comparative Example 1 of the present invention. [Figure 5] 1 is an SEM photograph of a calcium carbonate compound of Comparative Example 2 of the present invention. [Figure 6] 1 is an SEM photograph of a calcium carbonate compound of Comparative Example 3 of the present invention. [Figure 7] FIG. 2 is a partial perspective view schematically showing a heating tester. DETAILED DESCRIPTION OF THE INVENTION

[0029] The calcium carbonate compound, composition, molded plate, and inorganic molded body according to one embodiment of the present invention, as well as a method for producing the calcium carbonate compound, are described below. The present invention is not limited to these embodiments.

[0030] <Calcium carbonate compounds> The calcium carbonate compound of the present invention is an agglomerated particle having an average secondary particle diameter D2 of 1 μm or more and 10 μm or less as measured by a laser diffraction method. Agglomerated particles having an average secondary particle diameter D2 measured by a laser diffraction method within the above range are preferred because they have high dispersibility and excellent workability when mixed with resin, cement, etc. Furthermore, the excellent dispersibility of the calcium carbonate compound makes the resulting inorganic molded body have a uniform structure, further improving its strength.

[0031] In the calcium carbonate compound, the secondary particles are aggregated particles, and the average particle diameter D2 measured by the laser diffraction method is 1 μm or more and 10 μm or less, preferably 1.2 μm or more and 8 μm or less, more preferably 1.5 μm or more and 9 μm or less, and even more preferably 2 μm or more and 6 μm or less.

[0032] The calcium carbonate compound of the present invention has an acid-soluble silica content of 0.1% by mass or more. Since the acid-soluble silica functions as a crystal growth regulator, when the acid-soluble silica content is within the above range, the calcium carbonate compound forms aggregated particles, and the average particle size D2 of the secondary particles (aggregated particles) measured by the laser diffraction method can be adjusted to within the above range, which is preferable in terms of ease of use. In the calcium carbonate compound, the content of the acid-soluble silica is 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.4% by mass or more, and preferably 3% by mass or less, more preferably 2.5% by mass or less, even more preferably 2% by mass or less. If the content of the acid-soluble silica is below the above range, it becomes difficult to obtain secondary particles (aggregated particles) having the desired average particle size, and when the calcium carbonate compound is blended (used) in a building material, the filterability decreases, and the papermaking properties of the building material may become poor.

[0033] The calcium carbonate compound of the present invention has a sedimentation volume of 50 mL or less. When the sedimentation volume is within this range, the calcium carbonate compound forming agglomerated particles has excellent filterability, i.e., the average particle size of the resulting agglomerated particles is kept low, and the calcium carbonate compound has excellent dispersibility, so that the resulting inorganic molded body has a uniform structure and can have improved strength. In the calcium carbonate compound, the sedimentation volume is 50 mL or less, preferably 48 mL or less, more preferably 46 mL or less, and even more preferably 44 mL or less.

[0034] The calcium carbonate compound preferably contains calcium carbonate at 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. In the calcium carbonate compound, when the calcium carbonate is within the above range, the strength and fire resistance of the resulting inorganic molded body can be improved, which is preferable.

[0035] The crystal structure of the calcium carbonate compound is preferably at least one selected from the group consisting of calcite, aragonite, and vaterite, and more preferably calcite.

[0036] The calcium carbonate compound has aggregated particles which are aggregates of primary particles, and the average major diameter D1 of the primary particles as measured in an SEM image is preferably 0.1 μm or more and 5 μm or less, more preferably 0.2 μm or more and 4 μm or less, and even more preferably 0.3 μm or more and 3 μm or less. The calcium carbonate compound is an aggregated particle, an aggregate of primary particles, and when the calcium carbonate compound is blended (used) in a building material, the building material has excellent filterability and excellent papermaking properties, which is preferable. Furthermore, when the average major diameter D1 of the primary particles as measured in an SEM image is within the above range, the primary particles become uniform, which is preferable.

[0037] The calcium carbonate compound preferably has a ratio (D1 / D2) of 0.01 or more and 0.7 or less, more preferably 0.05 or more and 0.6 or less, and even more preferably 0.1 or more and 0.5 or less, where D1 is the average major diameter of the primary particles as measured in an SEM image and D2 is the average particle diameter of the secondary particles of the aggregated particles as measured by a laser diffraction method. In the calcium carbonate compound, when the (D1 / D2) is within the above range, the secondary particles become uniform, which is preferable.

[0038] The calcium carbonate compound preferably has a viscosity (10% viscosity) of 20 cP or less when dispersed in water at a concentration of 10% by mass, more preferably 18 cP or less, and even more preferably 16 cP or less. When the 10% viscosity of the calcium carbonate compound is within the above range, the calcium carbonate compound has excellent fluidity, high dispersibility when mixed with resin, cement, etc., and excellent workability, which is preferable. In addition, the excellent dispersibility of the calcium carbonate compound makes the structure of the resulting inorganic molded body uniform, which is preferable because it can further improve the strength.

[0039] The calcium carbonate compound preferably has an aspect ratio (D1 / D3) of the average major axis D1 of the primary particles in an SEM image to the average minor axis D3 of the primary particles in an SEM image of the primary particles of 1.5 or more and 6 or less, more preferably 1.6 or more and 5.5 or less, and even more preferably 1.7 or more and 5 or less. In the calcium carbonate compound, when the aspect ratio (D1 / D3) is within the above range, the dispersion of the calcium carbonate compound can suitably have a 10% viscosity within the above range.

[0040] The calcium carbonate compound preferably has an oil absorption of 40 mL / 100 g or more and 100 mL / 100 g or less, more preferably 45 mL / 100 g or more and 95 mL / 100 g or less, and even more preferably 50 mL / 100 g or more and 90 mL / 100 g or less.

[0041] The calcium carbonate compound has a BET specific surface area of ​​2 m 2 / g or more 20m 2 / g or less, and 2 / g or more 18m 2 / g or less is more preferable, and 5m 2 / g or more 16m 2 It is more preferable that the saturation coefficient is 1 / g or less. In the calcium carbonate compound, when the BET specific surface area is within the above range, the 10% viscosity of the calcium carbonate compound forming the aggregated particles is kept low, and the dispersibility of the calcium carbonate compound is excellent. As a result, the shrinkage of the heating surface and the increase in the back surface temperature during heating can each be suppressed to a higher level, which is preferable.

[0042] <Method of manufacturing calcium carbonate compounds> The method for producing the calcium carbonate compound is not particularly limited, and any known production method can be used. For example, the method for producing the calcium-based carbonate compound includes a preparation step of preparing a CaO-containing composition for producing the calcium-based carbonate compound, and a carbonation step of contacting the CaO-containing composition with carbon dioxide to form the calcium-based carbonate compound, thereby improving the fixation rate of carbon dioxide (CO2) in the calcium-based carbonate compound, which is a carbonate of the CaO-containing composition. Furthermore, by using the carbonate of the CaO-containing composition, it is possible to contribute to the reduction and effective use of waste and the reduction of carbon dioxide.

[0043] (CaO-containing composition for producing calcium carbonate compounds) The CaO-containing composition preferably contains a CaO-containing raw material containing acid-soluble silica, which contributes to the formation of aggregated particles of calcium carbonate compounds. The CaO-containing raw material is not particularly limited, but examples thereof include lime slag, incineration ash of paper sludge, incineration ash of chicken manure, cement sludge, incineration ash of cement sludge, etc. The lime slag is a waste material containing CaO, and its utilization is useful because it leads to effective utilization of resources, conservation of natural resources, and environmental protection.

[0044] In addition to the lime slag, the CaO-containing raw material may be derived from at least one of the following: paper sludge incineration ash, chicken manure incineration ash, cement sludge, cement sludge incineration ash, and hydrates thereof. Although various materials can be used as the CaO-containing raw material, the use of waste materials is preferred from the viewpoints of economy and waste reduction.

[0045] (Crushing process) The method for producing a calcium-based carbonate compound preferably includes, as the preparation step, a pulverization step of pulverizing the CaO-containing raw material. By the grinding process, free CaO particles (or free (CaO) m (H2O) n By grinding the CaO-containing raw material, the particles can be made finer, and a CaO-containing composition can be prepared that has a larger surface area and higher reactivity with carbon dioxide than the CaO-containing raw material before grinding. The CaO-containing raw material may be either a sieved product that has undergone a sieving process in which the CaO-containing raw material is sieved and the fraction that passes through the sieve is collected in addition to the crushing process as the preparation process, or an unsieved product that has not undergone the sieving process.

[0046] The pulverization method is not particularly limited, and a method using a known pulverizer can be adopted. Examples of pulverizers include roller mills, jet mills, high-speed rotary pulverizers such as hammer mills, cutter mills, and pin mills, container-driven mills such as rotary mills, vibration mills, and planetary mills, and media-agitating mills such as attritors, bead mills, ball mills, and rod mills.

[0047] The grinding time can be appropriately set in consideration of the content of free CaO in the target CaO-containing composition, particle size, etc. The grinding time is preferably from 10 seconds to 168 hours, more preferably from 10 minutes to 72 hours, and even more preferably from 30 minutes to 24 hours.

[0048] When a rotary mill such as a ball mill or a pot mill is used as the pulverizer, the rotation speed is preferably 10 rpm or more and 300 rpm or less, more preferably 50 rpm or more and 200 rpm or less, and even more preferably 60 rpm or more and 150 rpm or less.

[0049] The pulverization step may be carried out by either a dry method or a wet method. When the pulverization step is carried out by a wet method, water is usually used as a dispersion medium. The concentration of the CaO-containing raw material when dispersed in water can be appropriately set in consideration of pulverization efficiency, etc. The amount of CaO-containing raw material mixed per liter of water is preferably 10 g or more and 1000 g or less, more preferably 80 g or more and 500 g or less, and even more preferably 120 g or more and 400 g or less.

[0050] When the grinding step is carried out wet, the suspension may be directly subjected to the subsequent carbonation step, or may be dried before being subjected to the subsequent carbonation step.

[0051] As described above, by carrying out the pulverization step as the preparation step, a CaO-containing composition having high reactivity with carbon dioxide can be suitably prepared.

[0052] (Pretreatment process) The method for producing a calcium carbonate compound may include, as the preparation step, a pretreatment step of preparing a slurry of a mixture containing the CaO-containing composition and a silicon-containing compound (including acid-soluble silica) in order to adjust the acid-soluble silica content of the resulting calcium carbonate compound to a desired range. The slurry is then subjected to a carbonation step to obtain the calcium carbonate compound. The use of the silicon-containing compound allows the content of acid-soluble silica in the calcium carbonate compound to be adjusted to a desired range, and the calcium carbonate compound can be used to obtain aggregated particles having a secondary particle average particle diameter D2 measured by the laser diffraction method within a desired range, which is particularly useful when the CaO-containing composition does not contain acid-soluble silica or when the content of acid-soluble silica in the CaO-containing composition is low.

[0053] The silicon-containing compound is not particularly limited, but examples thereof include fumed silica, silica sol, and sodium silicate.

[0054] The content of acid-soluble silica in the silicon-containing compound is not particularly limited, but for example, if it is about 1 to 5 mass %, by appropriately adjusting the amount of the silicon-containing compound, a calcium carbonate compound can be obtained in which the content of acid-soluble silica is adjusted to a desired range.

[0055] (carbonation process) In the carbonation step, the CaO-containing composition from the preparation step is brought into contact with carbon dioxide (hereinafter also referred to as "carbon dioxide gas") to form a calcium carbonate compound. The carbonation method is not particularly limited, but a typical preferred method is a carbon dioxide gas method in which carbon dioxide gas is blown into a dispersion of a CaO-containing composition dispersed in water to carbonate the composition.

[0056] The solids concentration of the CaO-containing composition in the dispersion may be appropriately set in consideration of carbonation efficiency, but is preferably 10 g / L or more and 500 g / L or less, more preferably 20 g / L or more and 400 g / L or less, and even more preferably 30 g / L or more and 350 g / L or less.

[0057] When the grinding step is carried out dry, the resulting CaO-containing composition may be dispersed in water to have a concentration within the above range. When the grinding step is carried out in a wet manner, water may be added or removed so that the concentration of the resulting suspension of the CaO-containing composition falls within the above concentration range.

[0058] The carbon dioxide used in the carbonation step is preferably carbon dioxide emitted from a combustion engine. The carbon dioxide gas used in the carbon dioxide gas method can be a flue gas from a lime calciner installed near a calcium carbonate compound production plant, etc., or a carbon dioxide-containing exhaust gas emitted from a combustion engine such as a boiler or a waste incinerator. This makes it possible to reuse carbon dioxide generated secondarily in industrial processes, thereby contributing to a reduction in carbon dioxide emissions throughout the entire industrial process.

[0059] From the viewpoint of carbonation efficiency, the concentration of carbon dioxide in the carbonation step is preferably 1% by volume or more and 100% by volume or less, and may be 1% by volume or more and 50% by volume or less, 3% by volume or more and 40% by volume or less, or 5% by volume or more and 30% by volume or less.

[0060] From the viewpoint of carbonation efficiency, the temperature in the carbonation step (the temperature of the dispersion liquid) is preferably 5°C or higher and 95°C or lower, more preferably 15°C or higher and 85°C or lower, and even more preferably 25°C or higher and 75°C or lower.

[0061] From the viewpoint of carbonation efficiency and production capacity, the flow rate of the carbon dioxide gas is preferably 10 L / min or more and 200 L / min or less, more preferably 20 L / min or more and 180 L / min or less, and even more preferably 30 L / min or more and 150 L / min or less, per 10 kg of the charged raw material CaO.

[0062] In the carbonation step, stirring is preferably carried out in conjunction with blowing in carbon dioxide gas. When stirring is carried out using a stirring blade, the rotation speed is preferably 100 rpm or more and 600 rpm or less, more preferably 150 rpm or more and 550 rpm or less, and even more preferably 200 rpm or more and 500 rpm or less.

[0063] The carbonation reaction time may be appropriately set so that the carbonation reaction proceeds sufficiently, taking into consideration the concentration of the CaO-containing composition, the concentration and flow rate of carbon dioxide gas, etc. The carbonation reaction time is not limited, but is preferably from 0.5 hours to 20 hours, more preferably from 1 hour to 18 hours, and even more preferably from 2 hours to 15 hours.

[0064] In addition to the carbon dioxide gas method, a solution method is also suitable in which an alkali (NaOH, amine, etc.) is reacted with CO2 to produce Na2CO3 or an amine carbonate, which is then reacted with CaO to produce CaCO3.

[0065] By going through the above steps, a calcium-based carbonate compound can be produced as a carbonate of the CaO-containing composition. The resulting calcium-based carbonate compound may be filtered and dried to form a powder, or may be used as a calcium-based carbonate compound source in the form of a slurry or cake without being filtered and dried.

[0066] <Composition containing calcium carbonate compound> The present invention relates to a composition containing the calcium carbonate compound. Examples of the composition containing the calcium carbonate compound include compositions containing cement, paper, rubber, paint, etc. in addition to the calcium carbonate compound. Among these, the composition containing cement, etc. is preferred in terms of the amount used.

[0067] The composition of the present invention preferably further contains at least one selected from the group consisting of a resin and a rubber, and examples of the resin include thermosetting resins and thermoplastic resins, among which, from the viewpoint of versatility, it is preferable to use a thermoplastic resin, etc. Examples of the rubber include natural rubber, nitrile rubber, silicone rubber, fluororubber, urethane rubber, acrylic rubber, isoprene rubber, styrene rubber, and chloroprene rubber, and among which, from the viewpoint of versatility, it is preferable to use chloroprene rubber.

[0068] The composition of the present invention preferably has a P funnel flow time of 15 seconds or less, more preferably 10 seconds or less. In the composition containing the calcium carbonate compound, when the P funnel flow time is within the above range, the composition has excellent fluidity, resulting in a short flow time and excellent workability, which is preferable.

[0069] The composition of the present invention is preferably for use in an inorganic molded body. The calcium carbonate compound contains silica (acid-soluble silica) that contributes to hardening, and is therefore useful for applications such as the inorganic molded body.

[0070] <Applications of calcium carbonate compounds> The calcium carbonate compound is suitable for use in any application, including, but not limited to, for example, as a high-performance additive for inorganic molded bodies, such as building materials, a filler for resins, etc. Hereinafter, an embodiment in which the calcium carbonate compound is used in an inorganic molded body will be described.

[0071] <Inorganic molded body> The present invention relates to an inorganic molded body containing the calcium carbonate compound. The inorganic molded body containing the calcium carbonate compound uses a calcium carbonate compound containing acid-soluble silica, which contributes to hardening. Furthermore, the use of the calcium carbonate compound with excellent dispersibility makes the structure of the obtained inorganic molded body uniform, further improving its strength, making it useful.

[0072] The inorganic molded body is not particularly limited, and representative examples include molded boards for building materials, concrete structures (concrete molded bodies), etc. Applicable compositions and the like will be described in detail below depending on the application.

[0073] The inorganic molded bodies are molded bodies mostly composed of inorganic substances such as hydraulic materials and siliceous materials, and have properties such as fire resistance, light weight, high strength, and workability, and are therefore widely used for exterior wall materials, roof underlayment materials, eaves ceiling materials, etc. for houses, etc. They are also widely used for foundations, walls, pillars, floors, etc. of buildings where strength and fire resistance are required. By using a specific calcium-based carbonate compound in such a wide-ranging inorganic molded body, it is possible to reduce the environmental load throughout the entire industrial process.

[0074] (molded board for building materials) The molding board preferably contains a hydraulic material, a siliceous material, a reinforcing fiber material, and a calcium carbonate compound.

[0075] (hydraulic material) Examples of the hydraulic material include cementitious materials, gypsum, lime, slag, etc. Examples of the cementitious material 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.

[0076] The content of the hydraulic material is preferably 5% by mass or more and 45% by mass or less, more preferably 8% by mass or more and 42% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less, based on the total amount of materials constituting the molded board. By setting the content of the hydraulic material within the above range, it is possible to improve the physical properties of the molded board, such as bending strength and peel strength, and to prevent the molded board from becoming too high in bulk density, thereby improving workability during construction.

[0077] (siliceous material) Examples of the siliceous material 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, which will be described later.

[0078] The content of the siliceous material is preferably 10% by mass or more and 55% by mass or less, more preferably 12% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less, based on the total amount of materials constituting the molded board. If the content of the siliceous material is within the above range, it becomes possible to set the bending strength, bulk specific gravity, water absorption rate, dimensional stability, etc. of the molded board within the desired range. Incidentally, as the siliceous material, perlite, fly ash balloons, shirasu balloons, etc., having a unit volume mass of 0.5 g / cm are preferred. 3 When mixing the following lightweight aggregates, it is preferable to use other siliceous materials in combination so that the content of lightweight aggregate is 20 mass% or less, based on the total amount of materials constituting the molded board, in order to prevent the bulk density from becoming too light and weakening strength such as bending strength and peel strength.

[0079] (reinforcing fiber material) Examples of the reinforcing fiber material 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.

[0080] To improve the strength and toughness of the molded board, the content of the reinforcing fiber material is preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 26% by mass or less, and even more preferably 4% by mass or more and 22% by mass or less, based on the total amount of materials constituting the molded board. By setting the content of the reinforcing fiber material within the above range, it is possible to achieve a sufficient reinforcing effect while suppressing the protrusion of fibers from the surface of the molded board, thereby improving smoothness. When an inorganic reinforcing fiber material having an average fiber length of 1 mm or more and 50 mm or less is blended as the reinforcing fiber material, it is preferable to use another reinforcing fiber material in combination so that the content is 10% by mass or less, based on the total amount of materials constituting the molded board, in order to improve the smoothness of the molded board.

[0081] (Calcium carbonate compounds) As the calcium carbonate compound, the calcium carbonate compounds described above can be suitably used.

[0082] The content of the calcium carbonate compound is preferably 5% by mass to 60% by mass, more preferably 8% by mass to 55% by mass, and even more preferably 12% by mass to 50% by mass, based on the total amount of materials constituting the molded board. By blending a low thermal conductive calcium carbonate compound in an amount within the above range, the strength and fire resistance of the molded board can be improved.

[0083] (optional ingredient) In addition to the above materials, the molded board can be blended with various materials 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 molded board can be added as appropriate.

[0084] (Method of manufacturing molded plate) The method for producing the molded plate according to this embodiment is not particularly limited, and commonly used methods such as papermaking, extrusion, flow-on molding, casting, and press (compression) molding can be used. The molded plate can be obtained by subjecting a green sheet molded by these methods to press dehydration or patterning by embossing, etc., followed by curing at room temperature, steam curing, autoclave curing, etc. The molded plate can then be dried, and may be shaped or painted as necessary.

[0085] The bulk density of the molded plate is 0.7 g / cm 3 More than 2.0g / cm 3 Preferably, it is 0.8 g / cm or less. 3 More than 1.8g / cm 3 More preferably, it is 0.9 g / cm or less. 3 More than 1.6g / cm 3 It is even more preferable that:

[0086] The molded plate of the present invention, obtained by pressing a molded article of the composition, preferably has a surface change rate of 120% or less, more preferably 118% or less, and even more preferably 116% or less. When the surface change rate of the molded plate is within the above range, the moldability of the obtained inorganic molded body becomes constant, and the papermaking property is excellent, which is preferable. The molded article of the composition can be obtained by a papermaking method or the like, and a plurality of such molded articles can be laminated to produce a molded plate, which can then be pressed to measure the rate of change of area.

[0087] (Uses of molded boards) The uses of the molded board are not particularly limited, and the molded board can be suitably used as a performance maintaining material for architectural wall materials, floor materials, roofing materials, various boards, exterior decorative members, interior and exterior finishing materials such as fittings, sealing materials, heat insulating materials, sound absorbing materials, waterproofing materials, etc. The molded board is preferably a cementitious molded board containing a cementitious material, and more preferably a calcium silicate molded body.

[0088] (concrete structures) The concrete structure is composed of a hardened hydraulic composition. The hydraulic composition is made of a powder containing a calcium carbonate compound and at least one of blast furnace slag, expansive additive, slaked lime, quicklime, fly ash, and Portland cement. The calcium carbonate compound may be any of the calcium carbonate compounds described above.

[0089] 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 prepare a hydraulic composition mixture.

[0090] The hardened product of the hydraulic composition is obtained by hardening a paste obtained by kneading the hydraulic composition with water. The hardened product of the 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.

[0091] The ratio of the calcium carbonate compound in the powder (the ratio of the calcium carbonate compound to the cement) is preferably 1% by mass or more and 60% by mass or more, more preferably 3% by mass or more and 50% by mass or less, and even more preferably 5% by mass or more and 40% by mass or less.

[0092] It is desirable to use ground granulated blast furnace slag used in JIS (Japanese Industrial Standards) R5211 "blast furnace cement" or ground granulated blast furnace slag conforming to JIS A6206 "blast furnace slag for concrete" as the blast furnace slag. The blast furnace slag preferably has a specific surface area of ​​2000 cm 2 / g or more 10000cm 2 / g or less, more preferably 3500 cm 2 / g or more 7000cm 2 Use one that is equal to or less than / g.

[0093] The expansive material may be, for example, an expansive material specified in JIS A6202 “Expansive material for concrete.” The expansive material is preferably added in an amount of 2 to 9 mass % based on the total amount of the hydraulic composition.

[0094] The slaked lime may be, for example, that specified in JIS R9001 "Industrial Lime." Furthermore, since quicklime becomes slaked lime when it comes into contact with water, quicklime specified in JIS R9001 "Industrial Lime" may be used instead of slaked lime. In this case, it is advisable to adjust the amount of water required to convert quicklime into slaked lime. The fly ash may be, for example, that conforming to JIS A6201 "Fly Ash for Concrete."

[0095] As the Portland cement, ordinary Portland cement is used, but other types of Portland cement such as high-early-strength Portland cement, ultra-high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement, as specified in JIS R5210 "Portland cement," and JIS R5214 "Ecocement" can also be used.

[0096] When the hydraulic composition contains Portland cement, the proportion of Portland cement in the powder other than the calcium carbonate compound is 70% by mass or less, and preferably 30% by mass or less.

[0097] Furthermore, when Portland cement and blast furnace slag or fly ash are used, the components may be pre-mixed, for example, JIS R5211 "blast furnace cement" or, for example, JIS R5213 "fly ash cement," and the pre-mixed components may be used alone or in combination.

[0098] Since the hydraulic composition and the hydraulic composition mixture contain a calcium carbonate compound having the above characteristics, they exhibit good fluidity and the resulting hardened concrete can exhibit excellent compressive strength.

[0099] The density of the concrete structure is 0.7 g / cm 3 It is preferable that the concentration is 0.8 g / cm or more. 3 More preferably, it is 0.9 g / cm or more. 3 It is more preferable that the above condition is satisfied. This improves the strength of the concrete structure. [Example]

[0100] 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.

[0101] <Production of calcium carbonate compounds> [Example 1] After 6 L of water was poured into an 8 L stainless steel container equipped with a baffle, 1.0 kg of a CaO-containing composition (lime slag, manufactured by Konoshima Chemical Co., Ltd.) was added to the container under stirring. The temperature was then raised to 40 °C and stirred at 300 rpm using a stirrer equipped with turbine blades. A flue gas extraction pipe was connected to the exhaust outlet of a steam production boiler fueled by LNG (liquefied natural gas), and the flue gas was drawn in using a test blower. Measurement using a CO2 concentration meter (XP-3140, manufactured by New Cosmos Electric Co., Ltd.) revealed a CO2 concentration of 10% by volume. The flue gas was introduced into the 8 L stainless steel container at a rate of 3.3 L / min using a test blower and allowed to react for 10 hours. The mixture was then filtered, and the filtered wet material was dried at 110 °C for 12 hours and pulverized to obtain a sample powder of calcium carbonate compound 1 (see Figure 1). The CaO-containing composition used for analysis was dried at 110°C for 12 hours.

[0102] [Example 2] After 6 L of water was poured into an 8 L stainless steel vessel equipped with a baffle, 1.0 kg of a CaO-containing composition (slaked lime, manufactured by Tosa Lime Co., Ltd., industrial slaked lime No. 1, specially selected slaked lime) was added to the vessel under stirring. 3.0 mass% of No. 3 sodium silicate (JIS K1408) was then added and stirring continued. The temperature was then raised to 40 °C, and the mixture was stirred at 300 rpm using a turbine-type agitator. A flue gas extraction pipe was connected to the exhaust outlet of an LNG-fueled steam production boiler, and flue gas was drawn in using a test blower. Measurement using a CO2 concentration meter (XP-3140 manufactured by New Cosmos Electric Co., Ltd.) revealed a CO2 concentration of 10% by volume in the flue gas. The flue gas was introduced into the 8 L stainless steel vessel at a rate of 3.3 L / min using a test blower and allowed to react for 10 hours. Next, the mixture was filtered, and the filtered wet matter was dried at 110°C for 12 hours and pulverized to obtain a sample powder of calcium carbonate compound 2 (see Figure 2). Note that the sample dried at 110°C for 12 hours was used for the analysis of the CaO-containing composition.

[0103] [Example 3] After 6 L of water was poured into an 8 L stainless steel vessel equipped with a baffle, 1.0 kg of a CaO-containing composition (slaked lime, manufactured by Tosa Lime Co., Ltd., industrial slaked lime No. 1, specially selected slaked lime) was added to the vessel under stirring. 5.0 mass% silica sol (trade name Snowtex O, Nissan Chemical Co., Ltd.) was then added and stirring continued. The temperature was then raised to 40 °C, and stirring was continued at 300 rpm using a turbine-equipped mixer. A flue gas extraction pipe was connected to the exhaust outlet of an LNG-fueled steam production boiler, and flue gas was drawn in using a test blower. Measurement using a CO2 concentration meter (XP-3140, manufactured by New Cosmos Electric Co., Ltd.) revealed a CO2 concentration of 10% by volume in the flue gas. The flue gas was introduced into the 8 L stainless steel vessel using a test blower at a rate of 3.3 L / min and reacted for 10 hours. Next, the mixture was filtered, and the filtered wet matter was dried at 110°C for 12 hours and pulverized to obtain a sample powder of calcium carbonate compound 3 (see Figure 3). Note that the sample dried at 110°C for 12 hours was used for analysis of the CaO-containing composition.

[0104] [Comparative Example 1] After 6 L of water was poured into an 8 L stainless steel container equipped with a baffle, 1.0 kg of a CaO-containing composition (slaked lime, manufactured by Tosa Lime Co., Ltd., industrial slaked lime No. 1, specially selected slaked lime) was added to the container under stirring. The mixture was then heated to 40 °C and stirred at 300 rpm using a stirrer equipped with turbine blades. A flue gas extraction pipe was connected to the exhaust outlet of an LNG-fueled steam production boiler, and the flue gas was drawn in using a test blower. Measurement using a CO2 concentration meter (XP-3140 manufactured by New Cosmos Electric Co., Ltd.) revealed a CO2 concentration of 10% by volume. The flue gas was introduced into the 8 L stainless steel container at a rate of 3.3 L / min using a test blower and allowed to react for 10 hours. The mixture was then filtered, and the separated wet material was dried at 110 °C for 12 hours and pulverized to obtain a sample powder of calcium carbonate compound 4 (see Figure 4). The CaO-containing composition used for analysis was dried at 110°C for 12 hours.

[0105] Comparative Example 2 A CaO-containing composition (slaked lime, Tosa Lime Co., Ltd., industrial slaked lime No. 1, specially selected slaked lime), 232 g (calculated as CaO), 21 g of aragonite seed crystal powder, and 17 g of disodium hydrogen phosphate dodecahydrate were prepared and added to an 8 L stainless steel vessel equipped with a baffle, pre-filled with 6 L of water, while stirring to prepare a mixed slurry of the raw materials. The mixture was then heated to 70 °C and stirred at 300 rpm using a turbine-type agitator. A flue gas extraction pipe was connected to the exhaust outlet of an LNG-fueled steam production boiler. The exhaust gas was drawn in using a test blower. Measurements using a CO2 concentration meter (XP-3140, New Cosmos Electric Co., Ltd.) revealed a CO2 concentration of 10% by volume. The flue gas was introduced into the 8 L stainless steel vessel at a rate of 3.3 L / min using the test blower, and the reaction was carried out for 7 hours. Thereafter, the mixture was filtered, and the filtered wet matter was dried at 110° C. for 12 hours and pulverized to obtain a sample powder of calcium carbonate compound 5 (see FIG. 5).

[0106] Comparative Example 3 Sodium carbonate was prepared by adding 8510 g of sodium carbonate reagent (manufactured by Wako Pure Chemical Industries, purity 99.8%) to a 220 L stainless steel vessel with a baffle and containing 100 L of water under stirring. 2+ The solids (calcium carbonate content: 0.25 g / dL) were placed in a 2000 L polyethylene container, and 100 L of the above-mentioned sodium carbonate aqueous solution was added all at once while stirring at 25°C. After that, the solids were reacted by continuing to stir for about 30 minutes. After that, the solids were filtered, washed with about 5 times the amount of water relative to the solid content, dried at 110°C for 12 hours, and pulverized to obtain a sample powder of calcium carbonate compound 6 (see Figure 6).

[0107] <Evaluation> The calcium carbonate compounds obtained in the examples, cement milk, cement molded bodies, molded boards (laminated boards), and inorganic molded bodies obtained using the calcium carbonate compounds were evaluated and analyzed, and the evaluation results are shown in Table 1.

[0108] [BET specific surface area] The sample powder of calcium carbonate compound was pretreated in a nitrogen gas atmosphere at approximately 130°C for approximately 30 minutes using an 8-unit preheat unit (manufactured by MOUNTECH Co.), and the BET specific surface area (m) was measured by nitrogen gas adsorption using a Macsorb HM Model-1208 (manufactured by MOUNTECH Co.) as a BET specific surface area measuring device. 2 / g) was measured.

[0109] [Average particle size of secondary particles measured by laser diffraction (D2)] 50 mL of ethanol was placed in a 100 mL beaker, and approximately 0.2 g of calcium carbonate powder was added. 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) of secondary particles (aggregated particles).

[0110] [Crystal structure] After compressing the calcium carbonate powder onto a designated sample stage with a spatula, the sample was measured using an XRD device (MiniFlex600-C, manufactured by Rigaku Corporation) to identify the crystalline substance. Note that the peak appearing at a measurement angle 2θ of approximately 29° is the main peak of calcite, and the peak appearing at approximately 46° is the main peak of aragonite.

[0111] [Average major axis (D1), average minor axis (D3), and aspect ratio (D1 / D3)] Double-sided tape was attached to an aluminum sample stage, and a calcium carbonate powder sample was applied to the tape by tracing it with a spatula. After platinum deposition, particle images of the sample powder were taken at 10,000 magnification using a scanning electron microscope (FESEM: Hitachi S-4700). Using image analysis software (Image J), ​​20 particles were randomly selected from the SEM images, and the average values ​​of the long diameter, short diameter, and aspect ratio (ratio of long diameter to short diameter) of the primary particles were calculated.

[0112] [Scanning Electron Microscope Observation] A double-sided tape was attached to the aluminum sample stage, and the sample powder of the calcium-based carbonate compound was applied from above it in a tracing manner using the spatula blade. After platinum evaporation, the particle image of the sample powder was photographed with a scanning electron microscope (FE-SEM: S-4700 manufactured by Hitachi, Ltd.) at a magnification of 10,000 times. For the obtained calcium-based carbonate compounds 1 to 6, SEM photographs shown in FIGS. 1 to 6 were respectively taken, and their shapes were judged.

[0113] [Content of Acid-Soluble Silicon Dioxide] <ICP-AES Method> 0.2 g of the sample powder of the calcium-based carbonate compound was weighed, moistened with water, and 10 mL of hydrochloric acid (a solution obtained by mixing concentrated hydrochloric acid and water at a volume ratio of 1:1) was added using a pipette, followed by heating and dissolution. After filtering this mixed solution, the filtrate was cooled and then transferred to a 250 mL volumetric flask, and water was added to make up to 250 mL. From this, 20 mL was aliquoted into a 50 mL volumetric flask, and water was added to make up to 50 mL to obtain the test solution for measurement. On the other hand, 20 mL was aliquoted from the above-mentioned 250 mL made-up aqueous solution into a 50 mL volumetric flask, and a standard solution of silicon atoms (Si) was arbitrarily added in an additional amount to prepare calibration standard solutions with different concentrations. Note that a commercially available 1000 ppm standard solution for atomic absorption was used as the standard solution of silicon atoms. The calibration standard solutions with different concentrations to which silicon atoms were additionally added and the test solution for measurement were set in the autosampler of an inductively coupled plasma atomic emission spectrometry (ICP-AES) apparatus (manufactured by Hitachi High-Technologies Corporation, "SPECTROBLUE FMS36 type"), and the amount (ppm) of silicon atoms (Si) was measured under the following conditions. From the amount of the silicon atoms, the content (mass%) of acid-soluble silicon dioxide (s-SiO2) was calculated after conversion to oxide. (Measurement Conditions) High-frequency output: 1.4 kW Carrier gas (humidified) flow rate: 0.9 L / min Plasma gas flow rate: 13.0 L / min Liquidity: Aqueous solution Number of integrations: 3 Sample order: each sample Measurement method: Standard addition method Calibration curve weighting: None Measurement wavelength: Silicon atom: 251.612 nm

[0114] [CaCO3 content in calcium carbonate compounds] The content (mass%) of CaCO3 in the calcium carbonate compound was calculated using the following formula. The CaCO3 content in the calcium carbonate compound indicates the total content of CaCO3 derived from the raw material and CaCO3 newly immobilized with CO2.

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[0115] [Oil absorption amount] Take 2.00g of sample powder of calcium carbonate compound 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 coagulated sample and stop mixing when a sudden softening phenomenon occurs. Determine the amount of oil (mL) used until final solidification, and calculate the oil absorption per 100g of sample (mL / 100g) using the following formula.

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[0116] [10% viscosity] A sample powder of a calcium carbonate compound was dispersed in water to obtain a 10% by mass slurry. The viscosity (10% viscosity) of the resulting slurry was measured (cP) at 20°C using a BII type viscometer (manufactured by Toki Sangyo Co., Ltd.).

[0117] [Settling volume] A sample powder of a calcium carbonate compound was dispersed in water to obtain a 5% by mass slurry. 100 mL of the resulting slurry was transferred to a 100 mL measuring cylinder, which was then capped with a rubber stopper and manually shaken 100 times. The resulting slurry was allowed to stand for 30 minutes, and the sedimentation volume (mL) of the slurry was measured.

[0118] [P funnel flow time] (Cement milk production) 2 kg of cement (Tokuyama Corporation, "Normal Portland Cement (N)") was added to 1600 mL of water over a period of approximately 20 seconds, and 200 g of a calcium carbonate compound sample powder was added. The mixture was mixed with a mixer (Yamato Scientific Co., Ltd., "Labo Stirrer (LR500B)") for 3 minutes after the start of addition. After stopping the mixing and leaving it to stand for 3 minutes, the mixture was manually stirred 10 times with a stirring rod (As One Corporation, "Stirring rod (POM) φ10 x 300 mm") to produce cement milk. (P funnel flow time test method) The P funnel flow time was measured in accordance with the "Test method for fluidity of injection mortar for prepacked concrete (method using P funnel)" (JSCE-F521-1999). The outlet of the P funnel was held with a finger, and each of the prepared cement milks was poured up to the mark on the P funnel (1750 ml). Measurement was started as soon as the finger was released using a time watch, and the time (seconds) until the cement milk was discharged from the P funnel (P funnel flow time) was measured.

[0119] [Compression strength] (Production of cement molded body) 400 mL of the prepared cement milk was poured into a cylindrical polyethylene bag (approximately 50 mm in diameter x 550 mm in length x 0.05 mm in thickness) up to the marked line. After injecting as much air as possible to seal the bag, it was hung in a temperature-reducing machine set to 22°C. The bag was left hanging in the temperature-reducing machine for 28 days to harden the contents, producing a total of three cement molded bodies. The resulting cement molded bodies were cylindrical, approximately 5 cm in diameter and 20 cm in length.

[0120] (Compression strength test) The compressive strength of the resulting cement compact (N / mm2) was measured in accordance with JIS A1108:2018 (Method of compressive test for concrete). 2 ) was measured. The compressive strength is preferably 24 N / mm 2 More preferably, 25N / mm 2 More preferably, 26N / mm 2 That's all.

[0121] [Area change rate] (Manufacture of molded boards (laminated boards)) A molded plate (laminate) was produced by a papermaking method according to the following procedure. First, 27 parts by mass of cement, 23 parts by mass of silica sand, 5 parts by mass of pulp, 10 parts by mass of wollastonite, and 35 parts by mass of each of the calcium-based compounds obtained were placed in a plastic container as raw materials for the molded board, and the mixture was stirred and mixed to obtain a raw material slurry. Next, the raw material slurry was divided and poured into a filter lined with felt, and suction filtration was carried out using a vacuum pump to produce a molded plate (laminated plate, long side 28 mm x short side 24 mm x thickness 18 mm).

[0122] (Measurement of surface change rate) The resulting molded plate was removed from the filter, and the long side length (L1) and short side length (l1) were measured using a vernier caliper. After that, the plate was dewatered and pressed, and the long side length (L2) and short side length (l2) were measured again, and the area change rate (%) was calculated using the following formula.

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[0123] [Heating test] (Manufacturing of inorganic molded boards (inorganic molded bodies)) The molded plate (laminate plate) obtained by the above-mentioned manufacturing method of molded plate (laminate plate) was taken out of the filter and subjected to dehydration pressing. The thickness after pressing was 13 mm. Autoclave curing (curing pressure (gauge pressure): 9 kgf / cm 2 After curing for 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 plate (inorganic molded body) was obtained.

[0124] (Measurement of heat surface shrinkage and back surface temperature rise) The heating test was conducted using the following equipment and procedure. Figure 7 is a partial perspective view showing a schematic diagram of the heating tester. As shown in Figure 7, 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 of the backside of the test specimen (inorganic molded board). 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. The test procedure was as follows. (1) A scrap board was placed, preheating was performed up to 902°C, and then heating was performed once. (2) The specimen was inserted after the temperature of the heated surface had dropped 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, 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 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 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. The heating surface shrinkage (%) is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. The rise in the rear surface temperature before and after the test is preferably 460° C. or less, more preferably 455° C. or less, and even more preferably 450° C. or less.

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[0125] [Table 1]

[0126] From the evaluation results in Table 1 above, it was confirmed that in all Examples, the content of acid-soluble silica was within a predetermined range, agglomerated particles having an average particle size within a predetermined range were obtained, and the calcium carbonate compound had a settling volume within a predetermined range, and that the cement milk using this did not increase the P funnel flow time, had good fluidity, and was excellent in workability.In addition, it was confirmed that the compressive strength of the cement molded body was maintained high, the surface change rate of the molded board (laminated board) was kept small, and papermaking properties were excellent, and that the resulting inorganic molded board also suppressed heated surface shrinkage and backside temperature rise.

[0127] On the other hand, in Comparative Examples 1 and 2, the content of acid-soluble silica in the resulting calcium carbonate compound was low, and in Comparative Example 3, sodium carbonate was used instead of a calcium carbonate compound, and the content of acid-soluble silica was low. Therefore, compared to the Examples, it was confirmed that aggregated particles could not be formed and all properties could not be simultaneously satisfied.

Claims

1. Average particle diameter D of secondary particles by laser diffraction method ２ are aggregated particles having a size of 1 μm or more and 10 μm or less, The content of acid-soluble silica is 0.1% by mass or more and 3% by mass or less, Contains 70% by mass or more of calcium carbonate, A calcium carbonate compound having a sedimentation volume of 50 mL or less.

2. 2. The calcium carbonate compound according to claim 1, wherein the crystal structure of the calcium carbonate compound is at least one selected from the group consisting of calcite, aragonite, and vaterite.

3. the aggregated particles are aggregates of primary particles, The average major diameter D of the primary particles in the SEM image １ The calcium carbonate compound according to claim 1, wherein the particle size is 0.1 μm or more and 5 μm or less.

4. The average major diameter D of the primary particles in the SEM image １ and the average particle diameter D of the secondary particles of the aggregated particles by laser diffraction method ２ When １ / D ２ 4. The calcium carbonate compound according to claim 3, wherein the β-calcium carbonate content is 0.01 or more and 0.7 or less.

5. 2. The calcium carbonate compound according to claim 1, which has a viscosity (10% viscosity) of 20 cP or less when dispersed in water at a concentration of 10% by mass.

6. The average major diameter D of the primary particles in the SEM image １ The average minor diameter D of the primary particles in the SEM image ３ Aspect ratio (D １ / D ３ 4. The calcium carbonate compound according to claim 3, wherein the saturation coefficient (S) of the calcium carbonate is 1.5 or more and 6 or less.

7. 2. The calcium carbonate compound according to claim 1, having an oil absorption of 40 mL / 100 g or more and 100 mL / 100 g or less.

8. A composition comprising a calcium carbonate compound according to any one of claims 1 to 7.

9. The composition according to claim 8, further comprising at least one selected from the group consisting of a resin and a rubber.

10. 9. The composition of claim 8, having a P funnel flow time of 15 seconds or less.

11. The composition according to claim 8, which is for use in an inorganic molded body.

12. An inorganic formed body comprising the calcium carbonate compound according to any one of claims 1 to 7.

13. A molded plate obtained by pressing a molded article of the composition according to claim 8, wherein the surface change rate of the molded plate is 120% or less.

14. A method for producing a calcium carbonate compound according to any one of claims 1 to 7, a preparing step of preparing a CaO-containing composition; a pretreatment step of mixing a silicon-containing compound containing acid-soluble silica and the CaO-containing composition to prepare a slurry; and A method for producing a calcium carbonate compound, comprising a carbonation step of contacting the CaO-containing composition with carbon dioxide.

15. The method for producing a calcium carbonate compound according to claim 14, wherein the preparation step includes a sieving step.

16. The method for producing a calcium carbonate compound according to claim 14, wherein the preparation step includes a grinding step.

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