WO2023074086A1 - Method for producing calcium carbonate - Google Patents

Method for producing calcium carbonate Download PDF

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WO2023074086A1
WO2023074086A1 PCT/JP2022/030837 JP2022030837W WO2023074086A1 WO 2023074086 A1 WO2023074086 A1 WO 2023074086A1 JP 2022030837 W JP2022030837 W JP 2022030837W WO 2023074086 A1 WO2023074086 A1 WO 2023074086A1
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calcium carbonate
particles
slurry
substance
acid
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PCT/JP2022/030837
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French (fr)
Japanese (ja)
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雄己 毛塚
麻弥 吉田
健一郎 江口
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株式会社白石中央研究所
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Publication of WO2023074086A1 publication Critical patent/WO2023074086A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/18—Carbonates

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  • the present invention relates to a method for producing calcium carbonate.
  • Calcium carbonate (CaCO 3 ) is used as a base material and filler for various industrial products, and is also widely used in the fields of agriculture and food. Calcium carbonate is produced by blowing carbon dioxide into an aqueous solution of calcium hydroxide, or by mixing an aqueous solution of a soluble calcium salt such as calcium chloride and an aqueous solution of a soluble carbonate such as sodium carbonate.
  • quicklime (CaO) obtained by calcining and decarboxylating limestone (CaCO 3 ) is reacted with water to obtain milk of lime (an aqueous suspension of CaOH 2 ), and the dioxide obtained during calcination is converted into milk of lime.
  • the Shiraishi method in which carbon is introduced to produce calcium carbonate in a liquid, is widely known.
  • Calcium carbonate is mainly used as an inorganic filler in paper, rubber, sealing materials, plastics, etc.
  • Calcium carbonate for example, can improve the whiteness and opacity of paper by filling it in paper, and can improve the mechanical strength and abrasion resistance of rubber by adding it to rubber.
  • By adding calcium carbonate to the sealing material it is possible to adjust the viscosity and thixotropy of the sealing material. It can be performed. As described above, many attempts have been made to selectively produce calcium carbonate having a desired particle size, BET specific surface area, and desired crystal form according to various uses.
  • Patent Document 1 discloses a method for producing spindle-shaped calcium carbonate by introducing carbon dioxide gas into a calcium hydroxide suspension in the presence of water glass or silica sol, for use as coated paper, water-based dental fillers, or various fillers. Suggest. Non-Patent Document 1 discloses that crystal growth of calcium carbonate in the presence of silica inhibits the formation of coarse particles and the crystal growth of calcite single crystals.
  • Patent Document 1 is a method for modifying the surface of calcium carbonate in a conventionally known method for producing calcium carbonate, in which carbon dioxide is blown into an aqueous solution of calcium hydroxide.
  • Non-Patent Document 1 discloses that in the crystal growth of calcium carbonate, the presence of silica can suppress the formation of giant particles, but calcium carbonate having a desired BET specific surface area is intended. No disclosure is made as to how to obtain the target.
  • an object of the present invention is to provide a method for producing calcium carbonate having a particularly controlled shape and a desired BET specific surface area.
  • the present invention relates to a method for producing calcium carbonate, which uses an aqueous calcium carbonate slurry as a raw material and includes at least a calcium carbonate particle growth step for promoting the growth of calcium carbonate particles.
  • the calcium carbonate particle growth step is characterized in that a substance that generates silicate ions in an alkaline environment is added to the calcium carbonate aqueous slurry.
  • a substance that generates silicate ions in an alkaline environment can be added so that the concentration of silicon atoms relative to the mass of calcium carbonate is 100 ppm or more.
  • the substance that generates silicate ions in an alkaline environment is preferably one or more selected from the group consisting of amorphous silica, water glass, quartz, tridymite, cristobalite, feldspar, diatomaceous earth and ethyl silicate.
  • the calcium carbonate particle growth step in the present invention can be performed at a temperature of 50-210°C. Further, the calcium carbonate particle growth step in the present invention can be performed at pH 8-11.
  • the present invention can provide a novel method for intentionally and efficiently producing calcium carbonate having a controlled rhombohedral shape and a desired BET specific surface area.
  • FIG. 1 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Example 1.
  • FIG. 2 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Example 2.
  • FIG. 3 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Example 3.
  • FIG. 4 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Example 4.
  • FIG. 5 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Comparative Example 1.
  • An embodiment of the present invention is a method for producing calcium carbonate that uses an aqueous calcium carbonate slurry as a raw material and includes at least a calcium carbonate particle growth step that promotes the growth of calcium carbonate particles.
  • the outline of this embodiment is a method for obtaining calcium carbonate having a desired shape and BET specific surface area by growing particles from an aqueous calcium carbonate slurry as a raw material, that is, a production method related to Ostwald ripening.
  • the process of particle growth or crystal growth is sometimes referred to as "aging".
  • the calcium carbonate dispersed in the calcium carbonate aqueous slurry used as a raw material and the calcium carbonate produced are calcium carbonate represented by the composition formula CaCO3 , and are used in shells and chicken eggs. It is the main component of shells, limestone, and chalk. Calcium carbonate is classified into heavy calcium carbonate (natural calcium carbonate) obtained by pulverizing and classifying limestone and light calcium carbonate (synthetic calcium carbonate) obtained by chemical reaction. Any of them may be used as the calcium carbonate dispersed in the calcium carbonate aqueous slurry.
  • any of crystal polymorphs such as calcite crystal (trigonal rhombohedral crystal), aragonite crystal (orthogonal crystal), and vaterite crystal (hexagonal crystal) may be used for calcium carbonate.
  • the raw material calcium carbonate may have any particle size (number-based average particle size measured with an electron microscope), but preferably 20 to 500 nm, more preferably 30 to 100 nm.
  • the raw material calcium carbonate may have any BET specific surface area (Japanese Industrial Standard JIS Z 8830 ). It is preferable to use calcium carbonate in which calcium carbonate having a certain BET specific surface area is dispersed in water.
  • the step of growing calcium carbonate particles is preferably carried out as follows. First, an aqueous calcium carbonate slurry in which calcium carbonate is dispersed in water is prepared.
  • the term "calcium carbonate aqueous slurry” as used herein means an aqueous suspension (or aqueous dispersion) in which calcium carbonate is suspended or dispersed in water.
  • calcium carbonate and water can be mixed, and a conventional method such as stirring with a stirrer or stirring using ultrasonic waves can be appropriately performed.
  • the calcium carbonate aqueous slurry manufactured by the conventionally known Shiraishi method can also be used as it is.
  • the pH of the aqueous calcium carbonate slurry can be lowered, for example, by adding gaseous carbon dioxide to the gaseous calcium carbonate aqueous slurry, or by adding various acidic substances.
  • the method of adding gaseous carbon dioxide to the calcium carbonate aqueous slurry is not particularly limited.
  • the pH of the aqueous calcium carbonate slurry can be adjusted to about 5.5 to 11.0 by passing gaseous carbon dioxide while stirring the aqueous calcium carbonate slurry using a stirrer or the like.
  • inorganic acids such as carbonated water, hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, phosphoric acid, and boric acid, benzenesulfonic acid, acetic acid, citric acid, tartaric acid, and ascorbic acid.
  • Organic acids such as acids can be mentioned.
  • the acidic substance added to the aqueous calcium carbonate slurry may be in the form of gas, liquid or solid, but it is particularly preferred to add the acidic substance in a liquid or solid state. While stirring the calcium carbonate aqueous slurry using a stirrer or the like, these acidic substances can be added to adjust the pH of the calcium carbonate aqueous slurry to 5.5 to 11.0.
  • Calcium carbonate is dissolved by dissolving these acidic substances in water and tilting the calcium carbonate aqueous slurry to the acidic side. That is, at least part of the relatively small particle size calcium carbonate contained in the calcium carbonate aqueous slurry dissolves in water. On the other hand, calcium carbonate with a relatively large particle size dissolves at least in the peripheral portion thereof to become calcium carbonate with a slightly reduced particle size. At this stage, it is very preferable to adjust the pH of the calcium carbonate aqueous slurry so that all of the calcium carbonate does not dissolve.
  • the calcium carbonate aqueous slurry can contain a substance that produces silicate ions in an alkaline environment.
  • the alkaline environment means an environment with a pH in the range of 8.0 to 14.0.
  • Substances that generate silicate ions in an alkaline environment include condensed silicate ions such as orthosilicate ions, disilicate ions, and inosilicate ions, three-membered ring sorosilicate ions, and six-membered ring sorosilicate ions in alkaline solutions.
  • Substances that generate silicate ions in an alkaline environment include, for example, substances selected from the group consisting of amorphous silica, water glass, quartz, tridymite, cristobalite, feldspar, diatomaceous earth and ethyl silicate.
  • amorphous silica water glass, quartz, tridymite, cristobalite, feldspar, diatomaceous earth and ethyl silicate.
  • One or more of these substances can be used as the substance that generates silicate ions in an alkaline environment.
  • the pH of the aqueous calcium carbonate slurry can be adjusted to 5.5 to 9.0 after adding a substance that generates silicate ions in an alkaline environment to the aqueous calcium carbonate slurry. It is also possible to add a substance that generates silicate ions in an alkaline environment after adjusting to 5 to 9.0.
  • silicate ions When a substance that generates silicate ions in an alkaline environment is added to the calcium carbonate aqueous slurry, the above silicate ions will be present in the above calcium carbonate aqueous slurry. Silicate ions are present near the surface of calcium carbonate particles and suppress the growth of calcium carbonate particles, which will be described later. In order to control the growth of calcium carbonate particles and obtain calcium carbonate having a desired BET specific surface area, a substance that produces silicate ions in an alkaline environment should be added so that the concentration of silicon atoms relative to the mass of calcium carbonate is 100 ppm or more.
  • the concentration of silicon atoms relative to the mass of calcium carbonate can be 100 ppm or more and 100000 ppm or less, preferably 200 ppm or more and 50000 ppm or less, and more preferably 400 ppm or more and 30000 ppm or less.
  • calcium carbonate particles are grown from the calcium carbonate aqueous slurry in which silicate ions are present.
  • Calcium carbonate particles are allowed to grow by allowing the calcium carbonate aqueous slurry to stand still.
  • the calcium carbonate dissolved in the previous step gradually crystallizes.
  • a phenomenon is observed in which the particles remaining in the aqueous calcium carbonate slurry are aggregated and recrystallized, forming approximately cubic, approximately rectangular parallelepiped, or approximately rhombohedral particles.
  • calcium carbonate particles may be grown by gradually increasing the pH of the calcium carbonate aqueous slurry.
  • the calcium carbonate aqueous slurry In order to raise the pH of the calcium carbonate aqueous slurry, the calcium carbonate aqueous slurry is allowed to stand, the calcium carbonate aqueous slurry is stirred, the calcium carbonate aqueous slurry is depressurized, the calcium carbonate aqueous slurry is heated, and the calcium carbonate aqueous A method such as adding a basic substance to the slurry can be adopted.
  • the acidic substance added in the previous step is a gas such as carbon dioxide, the acidic substance gradually evaporates from the water even if the calcium carbonate aqueous slurry is left standing still. rises.
  • the calcium carbonate aqueous slurry is stirred, the pressure is reduced, the temperature is raised, or a basic substance is added. It's good to On the other hand, when the acidic substance added to the calcium carbonate aqueous slurry is liquid or solid, the calcium carbonate aqueous slurry may be stirred, decompressed, or heated to promote the pH increase. It is preferred to add a basic substance. While gently stirring the calcium carbonate aqueous slurry, it is very preferable to additionally perform other methods such as reducing pressure, increasing the temperature, and adding a basic substance.
  • the temperature is higher than room temperature (25°C), specifically about 50°C to 210°C, preferably about 70°C to 150°C, more preferably 80°C to 130°C. It is preferable to raise the temperature so that it falls within the range. That is, it is preferable that the growth process of calcium carbonate particles be carried out in such a manner that the temperature of the system is in the range of 50°C to 210°C.
  • the calcium carbonate aqueous slurry is decompressed, it is preferably decompressed to a pressure of less than atmospheric pressure to 10 2 Pa, preferably less than atmospheric pressure to about 1 ⁇ 10 5 Pa.
  • Examples of the basic substance that can be added to the aqueous calcium carbonate slurry include inorganic bases such as ammonia, sodium hydroxide, magnesium hydroxide and calcium hydroxide, organic bases such as amines and pyridines, and combinations thereof. be able to.
  • inorganic bases such as ammonia, sodium hydroxide, magnesium hydroxide and calcium hydroxide
  • organic bases such as amines and pyridines, and combinations thereof. be able to.
  • the pH should be increased to about 11.0.
  • the calcium carbonate dissolved in the previous step gradually crystallizes.
  • a phenomenon is observed in which the particles remaining in the aqueous calcium carbonate slurry are aggregated and recrystallized, forming approximately cubic, approximately rectangular parallelepiped, or approximately rhombohedral particles.
  • it is important to grow calcium carbonate particles at a pH between 8.0 and 11.0.
  • the step of lowering the pH of the aqueous calcium carbonate slurry and the step of raising the pH of the aqueous calcium carbonate slurry are repeated to grow the calcium carbonate particles, thereby obtaining the desired BET specific surface area. and calcium carbonate having the desired crystal form can also be produced.
  • Calcium carbonate produced by the method of the present embodiment is synthetic calcium carbonate.
  • calcium carbonate has crystal polymorphs such as calcite crystals (trigonal rhombohedral crystals), aragonite crystals (rectangular crystals), and vaterite crystals (hexagonal crystals), but is produced in the present embodiment.
  • Calcium carbonate preferably has a calcite structure.
  • Calcite crystals are generally in the form of crystals produced as calcite, and compared to other crystal forms, they are the most stable at normal temperature and normal pressure.
  • Calcium carbonate obtained in the present embodiment preferably has a calcite structure and a BET specific surface area of 2 to 50 m 2 /g.
  • the BET specific surface area can be determined by allowing a substance to adsorb gas molecules (nitrogen or the like) whose adsorption area is known and measuring the amount.
  • the BET specific surface area of calcium carbonate can be measured according to Japanese Industrial Standard JIS Z 8830 "Method for measuring specific surface area of powder (solid) by gas adsorption".
  • the BET specific surface area of calcium carbonate obtained in the embodiment is preferably 2 to 60 m 2 /g, more preferably 5 to 50 m 2 /g, still more preferably 8 to 45 m 2 /g.
  • the calcium carbonate produced by the method of the embodiment preferably has a number-based average particle size of 25 nm to 500 nm measured with an electron microscope.
  • Calcium carbonate having an average particle size of 25 to 500 nm means calcium carbonate in which calcium carbonate particles having a nano-order particle size account for the majority.
  • the average particle size of calcium carbonate produced by the method of the embodiment may be preferably 30-300 nm, more preferably 35-200 nm.
  • the calcium carbonate produced by the method of the embodiment may partially contain primary particles that are generally annular.
  • annular refers to all shapes having a single hole (ring) and all shapes having a cavity (hollow). The shapes include those having a single hole or cavity, and those having a cylindrical shape.
  • generally annular refers not only to a completely connected ring shape, but also to a partially incomplete ring shape such as a partly broken ring shape such as the letter C shape. intended to include
  • the calcium carbonate of the embodiment may partially contain substantially annular particles.
  • the size of the primary particles of calcium carbonate, which are generally annular is about 10 to 150 nm.
  • Calcium carbonate obtained in the embodiment may contain primary particles having a shape such as a spherical shape, a substantially cubic shape, a substantially cuboid shape, a substantially rhombohedral shape, a spindle shape, a needle shape, etc. in addition to the substantially annular primary particles. good.
  • the calcium carbonate produced by the method of the embodiment may include primary particles having a shape such as a spherical shape or a substantially rectangular parallelepiped shape, in which a part of the primary particles is concave, that is, those in which the pores are not completely open. .
  • Calcium carbonate produced by the method of the embodiment is surface-treated with a surface treatment agent selected from the group consisting of fatty acids and derivatives thereof, resin acids and derivatives thereof, silica, organosilicon compounds, condensed phosphoric acid and condensed phosphates.
  • a surface treatment agent selected from the group consisting of fatty acids and derivatives thereof, resin acids and derivatives thereof, silica, organosilicon compounds, condensed phosphoric acid and condensed phosphates.
  • fatty acids include lower fatty acids such as acetic acid and butyric acid, and higher fatty acids such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid.
  • resin acids include resin-derived acids such as abietic acid, neoabietic acid, parastric acid, pimaric acid, isopimaric acid, and dehydroabietic acid.
  • Silica is a compound (silicon dioxide) represented by the composition formula SiO2 .
  • the organic silicon compound for example, a functional group (vinyl group, epoxy group, amino group, methacrylic group, mercapto group, etc.) that bonds to an organic material and a functional group that bonds to an inorganic material (methoxy group, ethoxy group, etc.) in one molecule. group etc.) are bonded via a silicon atom (Si).
  • condensed phosphoric acid include inorganic polymer compounds obtained by heating and dehydrating orthophosphoric acid. These surface treatment agents can be used singly or in combination of two or more.
  • the resin is preferably selected from the group consisting of polyolefin resins, polyester resin compositions, polyarylate resin compositions, elastomer resins such as various diene resins, and mixtures thereof.
  • Elastomer resins such as polyolefin resins, polyvinyl chloride resins, polyester resins, polyarylate resins and diene resins may be used alone or in combination.
  • resins other than elastomer resins such as polyolefin resins, polyester resins, polyarylate resins, diene resins, and mixtures thereof may be included as necessary within a range that does not impair the object of the present invention.
  • Polyolefin resins are homopolymers, copolymers, and mixtures thereof obtained by polymerizing olefin (alkene) or cyclic olefin monomers.
  • polyolefin resins include polyethylene, polypropylene, poly-4-methylpentene-1, polybutene-1, poly-1-hexene, ethylene-tetracyclododecene copolymer, and polyacetal.
  • PVC polyvinyl chloride
  • a homopolymer of a vinyl chloride monomer or a copolymer of a vinyl chloride monomer and another monomer that can be copolymerized can be used.
  • polyester resins are polyesters composed of polycondensates of polyvalent carboxylic acids and polyols, and mixtures thereof. As the polyester resin, an aromatic polyester resin is preferably used.
  • aromatic polyester resins examples include polymethylene terephthalate resin (PTT), polyethylene terephthalate resin (PET), polypropylene terephthalate resin, polybutylene terephthalate resin (PBT), polyethylene naphthalate resin (PEN), polybutylene naphthalate resin ( PBN), poly(cyclohexane-1,4-dimethylene-terephthalate) resins, polytrimethylene terephthalate resins.
  • alkylene terephthalate copolymers containing alkylene terephthalate structural units as main structural units and polyalkylene terephthalate mixtures containing polyalkylene terephthalate as a main component can be mentioned.
  • polyalkylene terephthalates include, for example, mixtures of PBT and polyalkylene terephthalates other than PBT, and mixtures of PBT and alkylene terephthalate copolyesters other than PBT. Among them, a mixture of PBT and PET, a mixture of PBT and polytrimethylene terephthalate, a mixture of PBT and PBT/polyalkyleneisophthalate, and the like are preferable.
  • diene-based elastomer resins include rubber materials obtained by polymerizing diene-based monomers such as polybutadiene, polyisoprene, and polychloroprene. Elastomer resins such as urethane rubber, silicone rubber, and fluororubber may also be used.
  • the calcium carbonate obtained by the production method of the embodiment can be used in modified silicone resins, polyurethane resins, polysulfide resins, acrylic sols, rosin-modified alkyd resins, various acrylate resins, as well as resin mixtures and coating compositions containing the above resins. For example, it can be added to acrylic resin paints, polyurethane resin paints, acrylic silicone resin paints, or fluorine resin paints.
  • the resin composition containing calcium carbonate of the embodiment contains ordinary additives such as antioxidants, plasticizers, heat stabilizers, ultraviolet absorbers, fibrous reinforcing agents, lubricants, flame retardants, antistatic agents, Colorants and pigments can be contained.
  • plasticizers generally used in PVC sol compositions can be used, and phthalic acid-based plasticizers such as di-n-octyl phthalate (DOP), di-2-ethylhexyl phthalate, and diisononyl phthalate (DINP) can be used.
  • DOP di-n-octyl phthalate
  • DINP diisononyl phthalate
  • the amount of the plasticizer to be used is appropriately selected according to physical properties such as viscosity, curability, hardness after curing, and stability of the plastisol. preferably.
  • the content of additives other than the plasticizer is preferably 10 mass % or less of the resin composition.
  • the calcium carbonate produced by the method of the embodiment may partially contain substantially annular primary particles.
  • Calcium carbonate containing substantially annular primary particles can be used as it is, and it is also possible to selectively separate the substantially annular primary particles. Separation of the substantially annular primary particles can be carried out, for example, by sieving to extract calcium carbonate particles having a particle size within a specific range, and then separating only the substantially annular primary particles by microscopic observation.
  • the calcium carbonate produced by the method of the embodiment can be mixed with various resins and used as a resin composition.
  • calcium carbonate can also be used as a filler for paper, paint, ink, and the like.
  • it can also be used as a filler for foods, cosmetics and the like.
  • the approximately cyclic calcium carbonate obtained by the separation operation can be expected to be used, for example, as a template for nanomaterials, a drug carrier, a catalyst carrier, and a lightweight filler by utilizing its special shape.
  • Example 1 Production of calcium carbonate according to the present invention
  • Carbon dioxide gas was introduced into the slurry of calcium hydroxide to obtain calcium carbonate particles.
  • the BET specific surface area of the obtained calcium carbonate was 35.6 m 2 /g (Japanese Industrial Standard JIS Z 8830), and the number-based average particle size measured with an electron microscope was 44 nm (crystallite size was 51 nm).
  • Amorphous silica (Takashi Co., Ltd. Pure Chemical Laboratory) was added.
  • the beaker was heated to a temperature of 95° C. while gently stirring the calcium carbonate aqueous slurry containing amorphous silica.
  • Example 2-6 In Example 1, the amount of amorphous silica added to the calcium carbonate aqueous slurry was added so that the concentration of silicon atoms with respect to the mass of calcium carbonate was 1900 ppm, and aging was performed until the pH reached 10.0. Example 1 was repeated (Example 2). Calcium carbonate with a BET specific surface area of 14.9 m 2 /g and a crystallite size of 97 nm was obtained (Fig. 2). In Example 1, the amount of amorphous silica added to the calcium carbonate aqueous slurry was added so that the concentration of silicon atoms with respect to the mass of calcium carbonate was 7800 ppm, and aging was performed until the pH reached 8.9.
  • Example 1 was repeated (Example 3). Calcium carbonate with a BET specific surface area of 19.1 m 2 /g and a crystallite size of 80 nm was obtained (Fig. 3). In Example 1, the amount of amorphous silica added to the calcium carbonate aqueous slurry was added so that the concentration of silicon atoms with respect to the mass of calcium carbonate was 31000 ppm, and aging was performed until the pH reached 8.6. Example 1 was repeated (Example 4). Calcium carbonate with a BET specific surface area of 20.2 m 2 /g and a crystallite size of 77 nm was obtained (Fig. 4).
  • Example 1 the substance added to the calcium carbonate aqueous slurry was changed to water glass (Central Glass Co., Ltd.), added so that the concentration of silicon atoms relative to the mass of calcium carbonate was 1900 ppm, and aged to pH 10.9. Example 1 was repeated except what was done (Example 5). Calcium carbonate with a BET specific surface area of 14.6 m 2 /g and a crystallite size of 98 nm was obtained. In Example 1, the amount of amorphous silica added to the calcium carbonate aqueous slurry was such that the concentration of silicon atoms relative to the mass of calcium carbonate was 1900 ppm, the temperature during aging was 60°C, and the aging was carried out at pH 10.0. Example 1 was repeated except that it went to 7 (Example 6). Calcium carbonate with a BET specific surface area of 13.6 m 2 /g and a crystallite size of 105 nm was obtained.
  • Example 1 was repeated except that in Example 1 no amorphous silica was added (Comparative Example 1). Calcium carbonate with a BET specific surface area of 12.4 m 2 /g and a crystallite size of 114 nm was obtained (Fig. 5). Example 1 was repeated except that no amorphous silica was added, the aging time was 2 hours, and the aging was carried out to pH 12 (Comparative Example 2). Calcium carbonate with a BET specific surface area of 19.5 m 2 /g and a crystallite size of 82 nm was obtained. Example 1 was repeated except that no amorphous silica was added, the aging time was 1 hour, and the aging was performed until pH 12 (Comparative Example 3).
  • Example 1 Calcium carbonate having a BET specific surface area of 21.0 m 2 /g and a crystallite size of 80 nm was obtained.
  • the calcium carbonate obtained in Comparative Example 1 was mixed with the calcium carbonate before aging in Comparative Example 1 (Comparative Example 4).
  • Example 1 was repeated except that no amorphous silica was added and the aging time was 0.5 hours (Comparative Example 5). Calcium carbonate with a BET specific surface area of 25.2 m 2 /g and a crystallite size of 71 nm was obtained.
  • a polyvinyl chloride (PVC) sol was prepared using each surface-treated calcium carbonate obtained in Examples 1-6 and Comparative Examples 1-5.
  • the PVC sol consists of 200 g of each surface-treated calcium carbonate, 300 g of PVC resin (trade name “ZEST P21”, Shin-Daiichi PVC Co., Ltd.), 300 g of diisononyl phthalate (DINP) as a plasticizer, and heavy calcium carbonate (trade name “White P-30", Shiraishi Kogyo Co., Ltd.) 150 g, tackifier (trade name "Versamide 140", Henkel Japan) 10 g, and diluent (trade name "Mineral Turpen", Sankei Sangyo Co., Ltd.) 40 g Prepared by kneading. The viscosity of each PVC sol was measured.
  • a polyvinyl chloride (PVC) resin composition was prepared using each surface-treated calcium carbonate obtained in Examples 1-6 and Comparative Examples 1-5.
  • the composition of each component is as follows: ⁇ Vinyl chloride resin (trade name “Kanevinyl S-1001”, Kaneka Co., Ltd.): 100 parts by mass ⁇ Core-shell polymer composition (trade name “Kane Ace FM-40”, white resin powder, Kaneka Co., Ltd.): 3.5 Parts by mass
  • Each surface-treated calcium carbonate obtained in Examples and Comparative Examples 10 parts by mass Organic tin stabilizer (trade name “TM-181FSJ”, methyltin mercapto stabilizer, Katsuta Kako Co., Ltd.)1.
  • the resulting raw material mixture is kneaded using a 20 mm co-rotating twin-screw extruder under the conditions of an extrusion temperature of 170° C., a screw rotation speed of 100 rpm, and a discharge rate of 5 kg/hr to obtain pellets of a vinyl chloride resin composition. rice field.
  • a molded article was produced with an injection molding machine having a clamping force of 75 tons.
  • a molded body for measuring the Charpy impact strength was obtained using an ISO-A mold to obtain a test piece having a thickness of 4 mm.
  • a mold of ISO-D2 was used to obtain a plate-shaped molded body having a thickness of 2 mm, a length of 50 mm and a width of 50 mm.
  • the Charpy impact strength of the calcium carbonate-filled PVC resin composition molded article obtained above was measured with a notch according to ISO179-1 and -2.
  • the unit of strength is kJ/ m2 .
  • the B-type rotational viscosities (2 rpm and 20 rpm) of the calcium-filled PVC resin composition were measured by the method described above to determine the ratio of the two rotational viscosities (thixotropic index (TI)).
  • Calcium carbonate produced by the method of the present invention in which calcium carbonate crystals grow in the presence of a substance (amorphous silica) that produces silicate ions in an alkaline environment exhibits high thixotropic properties when mixed with PVC.
  • a PVC resin composition having high impact strength can be provided.
  • calcium carbonate having a relatively small particle size can be obtained in spite of the aging time. be able to.
  • the presence of silicate ions in the environment for crystal growth of calcium carbonate somewhat inhibits the crystal growth of calcium carbonate, making it difficult for the particles to form large particles.

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Abstract

The purpose of the present invention is to provide a method for producing calcium carbonate having a controlled shape and a desired BET specific surface area.　Provided is a method for producing calcium carbonate, the method comprising at least a calcium carbonate particle growth step for promoting the growth of calcium carbonate particles by using a calcium carbonate water slurry as a raw material, and being characterized in that, in the calcium carbonate particle growth step, a substance that generates silicate ions in an alkaline environment is added to the calcium carbonate water slurry.

Description

炭酸カルシウムの製造方法Method for producing calcium carbonate
　本発明は、炭酸カルシウムの製造方法に関する。 The present invention relates to a method for producing calcium carbonate.
　炭酸カルシウム（ＣａＣＯ３）は、各種工業製品の基材や填料として用いられるほか農業や食品の分野でも広く利用されている。炭酸カルシウムは、水酸化カルシウムの水溶液に二酸化炭素を吹き込むことや、塩化カルシウム等の可溶性カルシウム塩水溶液と炭酸ナトリウム等の可溶性炭酸塩水溶液を混合させることで製造される。一方、石灰石（ＣａＣＯ３）を焼成し脱炭酸して得られた生石灰（ＣａＯ）を水と反応させて石灰乳（ＣａＯＨ２の水懸濁液）を得、石灰乳に焼成時に得られた二酸化炭素を導入して、液中で炭酸カルシウムを製造する白石法が広く知られている。 Calcium carbonate (CaCO 3 ) is used as a base material and filler for various industrial products, and is also widely used in the fields of agriculture and food. Calcium carbonate is produced by blowing carbon dioxide into an aqueous solution of calcium hydroxide, or by mixing an aqueous solution of a soluble calcium salt such as calcium chloride and an aqueous solution of a soluble carbonate such as sodium carbonate. On the other hand, quicklime (CaO) obtained by calcining and decarboxylating limestone (CaCO 3 ) is reacted with water to obtain milk of lime (an aqueous suspension of CaOH 2 ), and the dioxide obtained during calcination is converted into milk of lime. The Shiraishi method, in which carbon is introduced to produce calcium carbonate in a liquid, is widely known.
　炭酸カルシウムは、主に無機充填材として、紙、ゴム、シーリング材料、プラスチック等に適用されている。炭酸カルシウムは、たとえば、紙に充填することで、紙の白色度や不透明度を向上させたり、ゴムに添加することで、ゴムの力学的強度や耐摩耗性を改善したりすることができる。また炭酸カルシウムをシーリング材料に添加することで、シーリング材料の粘度やチキソ性（チクソ性）を調整することができ、炭酸カルシウムをプラスチックに添加すると、プラスチックの力学的強度の向上や熱特性の調整を行うことができる。このように、炭酸カルシウムの各種用途に応じた所望の粒子径やＢＥＴ比表面積、ならびに所望の結晶形を有するものを作り分ける試みが多数行われている。特許文献１は、塗工紙または水系歯科用填剤あるいは各種充填剤として使用すべく、水ガラスまたはシリカゾルの存在下水酸化カルシウム懸濁液に炭酸ガスを導入して紡錘型炭酸カルシウムを製造する方法を提案する。また非特許文献１には、シリカの存在下で炭酸カルシウムを結晶成長させることにより、粗大粒子の形成やカルサイト単結晶の結晶成長を阻害することが開示されている。 　Calcium carbonate is mainly used as an inorganic filler in paper, rubber, sealing materials, plastics, etc. Calcium carbonate, for example, can improve the whiteness and opacity of paper by filling it in paper, and can improve the mechanical strength and abrasion resistance of rubber by adding it to rubber. By adding calcium carbonate to the sealing material, it is possible to adjust the viscosity and thixotropy of the sealing material. It can be performed. As described above, many attempts have been made to selectively produce calcium carbonate having a desired particle size, BET specific surface area, and desired crystal form according to various uses. Patent Document 1 discloses a method for producing spindle-shaped calcium carbonate by introducing carbon dioxide gas into a calcium hydroxide suspension in the presence of water glass or silica sol, for use as coated paper, water-based dental fillers, or various fillers. Suggest. Non-Patent Document 1 discloses that crystal growth of calcium carbonate in the presence of silica inhibits the formation of coarse particles and the crystal growth of calcite single crystals.
特開昭５８－１１５０２２号公報JP-A-58-115022
　特許文献１の方法は、炭酸カルシウムの製造方法として従来から知られている、水酸化カルシウム水溶液に二酸化炭素を吹き込む方法において、炭酸カルシウムの表面を改質する方法である。一方、非特許文献１には、炭酸カルシウムの結晶成長において、シリカを存在させることにより巨大粒子の生成を抑制することができることが開示されているが、所望のＢＥＴ比表面積を有する炭酸カルシウムを意図的に得る方法については開示されていない。 The method of Patent Document 1 is a method for modifying the surface of calcium carbonate in a conventionally known method for producing calcium carbonate, in which carbon dioxide is blown into an aqueous solution of calcium hydroxide. On the other hand, Non-Patent Document 1 discloses that in the crystal growth of calcium carbonate, the presence of silica can suppress the formation of giant particles, but calcium carbonate having a desired BET specific surface area is intended. No disclosure is made as to how to obtain the target.
　そこで本発明は、特に制御された形状を有し、かつ所望のＢＥＴ比表面積を有する炭酸カルシウムを製造する方法を提供することを目的とする。 Therefore, an object of the present invention is to provide a method for producing calcium carbonate having a particularly controlled shape and a desired BET specific surface area.
　本発明は、炭酸カルシウム水スラリーを原料として、炭酸カルシウムの粒子の成長を促進させる炭酸カルシウム粒子成長工程を少なくとも含む、炭酸カルシウムの製造方法にかかる。炭酸カルシウム粒子成長工程において、アルカリ環境下でケイ酸イオンを生じる物質を炭酸カルシウム水スラリー中に添加することを特徴とする。 The present invention relates to a method for producing calcium carbonate, which uses an aqueous calcium carbonate slurry as a raw material and includes at least a calcium carbonate particle growth step for promoting the growth of calcium carbonate particles. The calcium carbonate particle growth step is characterized in that a substance that generates silicate ions in an alkaline environment is added to the calcium carbonate aqueous slurry.
　本発明における炭酸カルシウム粒子成長工程において、アルカリ環境下でケイ酸イオンを生じる物質を、炭酸カルシウムの質量に対するケイ素原子の濃度が１００ｐｐｍ以上となるように添加することができる。 In the step of growing calcium carbonate particles in the present invention, a substance that generates silicate ions in an alkaline environment can be added so that the concentration of silicon atoms relative to the mass of calcium carbonate is 100 ppm or more.
　また、アルカリ環境下でケイ酸イオンを生じる物質は、非晶質シリカ、水ガラス、石英、トリジマイト、クリストバライト、長石、珪藻土およびケイ酸エチルからなる群より選択される１種以上であることが好ましい。
　本発明における炭酸カルシウム粒子成長工程は、５０～２１０℃の温度で行われることができる。
　さらに本発明における炭酸カルシウム粒子成長工程は、ｐＨ８～１１で行われることができる。 Further, the substance that generates silicate ions in an alkaline environment is preferably one or more selected from the group consisting of amorphous silica, water glass, quartz, tridymite, cristobalite, feldspar, diatomaceous earth and ethyl silicate. .
The calcium carbonate particle growth step in the present invention can be performed at a temperature of 50-210°C.
Further, the calcium carbonate particle growth step in the present invention can be performed at pH 8-11.
　本発明は、菱面体等に制御された形状を有し、所望のＢＥＴ比表面積を有する炭酸カルシウムを、意図的かつ効率的に製造する新規の方法を提供することができる。 The present invention can provide a novel method for intentionally and efficiently producing calcium carbonate having a controlled rhombohedral shape and a desired BET specific surface area.
図１は、実施例１で製造された炭酸カルシウムの電子顕微鏡写真（倍率８００００倍）である。FIG. 1 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Example 1. FIG. 図２は、実施例２で製造された炭酸カルシウムの電子顕微鏡写真（倍率８００００倍）である。FIG. 2 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Example 2. FIG. 図３は、実施例３で製造された炭酸カルシウムの電子顕微鏡写真（倍率８００００倍）である。FIG. 3 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Example 3. FIG. 図４は、実施例４で製造された炭酸カルシウムの電子顕微鏡写真（倍率８００００倍）である。FIG. 4 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Example 4. FIG. 図５は、比較例１で製造された炭酸カルシウムの電子顕微鏡写真（倍率８００００倍）である。5 is an electron micrograph (magnification: 80000) of calcium carbonate produced in Comparative Example 1. FIG.
　本発明の実施形態について、さらに詳細に説明するが、本発明は、以下の実施形態にのみ限定されるものではない。 Although the embodiments of the present invention will be described in more detail, the present invention is not limited only to the following embodiments.
　本発明の実施形態は、炭酸カルシウム水スラリーを原料として、炭酸カルシウムの粒子の成長を促進させる炭酸カルシウム粒子成長工程を少なくとも含む、炭酸カルシウムの製造方法である。本実施形態の概略は、原料となる炭酸カルシウム水スラリーから粒子を成長させることにより、所望の形状やＢＥＴ比表面積を有する炭酸カルシウムを得る方法、すなわちオストワルド熟成に関連した製造方法である。なお、本明細書において、粒子の成長あるいは結晶成長の過程を、「エージング」と表記することもある。 An embodiment of the present invention is a method for producing calcium carbonate that uses an aqueous calcium carbonate slurry as a raw material and includes at least a calcium carbonate particle growth step that promotes the growth of calcium carbonate particles. The outline of this embodiment is a method for obtaining calcium carbonate having a desired shape and BET specific surface area by growing particles from an aqueous calcium carbonate slurry as a raw material, that is, a production method related to Ostwald ripening. In this specification, the process of particle growth or crystal growth is sometimes referred to as "aging".
　本実施形態において、原料として使用する炭酸カルシウム水スラリーに分散している炭酸カルシウム、ならびに、製造される炭酸カルシウムとは、組成式ＣａＣＯ３で表されるカルシウムの炭酸塩であり、貝殻、鶏卵の殻、石灰岩、白亜などの主成分である。炭酸カルシウムは、石灰石を粉砕、分級して得られる重質炭酸カルシウム（天然炭酸カルシウム）と化学反応により得られる軽質炭酸カルシウム（合成炭酸カルシウム）とに分類されるが、本実施形態で原料として使用する炭酸カルシウム水スラリーに分散している炭酸カルシウムは、それらのいずれであっても良い。また炭酸カルシウムは、カルサイト結晶（三方晶系菱面体晶）、アラゴナイト結晶（直方晶系）、バテライト結晶（六方晶）等の結晶多形のうち、いずれのものを使用しても良い。原料炭酸カルシウムの粒子径（電子顕微鏡で測定した個数基準による平均粒子径）は、いかなるのでも良いが、好ましくは２０～５００ｎｍ、さらに好ましくは３０～１００ｎｍのものを使用することができる。また、原料炭酸カルシウムのＢＥＴ比表面積（日本工業規格ＪＩＳ　Ｚ　８８３０）はいかなるものでも良いが、本実施形態により所望のＢＥＴ比表面積を有する炭酸カルシウムを製造するためには、２～５０ｍ２／ｇ程度のＢＥＴ比表面積を有する炭酸カルシウムが水に分散した炭酸カルシウムを用いるのが好適である。 In the present embodiment, the calcium carbonate dispersed in the calcium carbonate aqueous slurry used as a raw material and the calcium carbonate produced are calcium carbonate represented by the composition formula CaCO3 , and are used in shells and chicken eggs. It is the main component of shells, limestone, and chalk. Calcium carbonate is classified into heavy calcium carbonate (natural calcium carbonate) obtained by pulverizing and classifying limestone and light calcium carbonate (synthetic calcium carbonate) obtained by chemical reaction. Any of them may be used as the calcium carbonate dispersed in the calcium carbonate aqueous slurry. Any of crystal polymorphs such as calcite crystal (trigonal rhombohedral crystal), aragonite crystal (orthogonal crystal), and vaterite crystal (hexagonal crystal) may be used for calcium carbonate. The raw material calcium carbonate may have any particle size (number-based average particle size measured with an electron microscope), but preferably 20 to 500 nm, more preferably 30 to 100 nm. In addition, the raw material calcium carbonate may have any BET specific surface area (Japanese Industrial Standard JIS Z 8830 ). It is preferable to use calcium carbonate in which calcium carbonate having a certain BET specific surface area is dispersed in water.
　実施形態において、炭酸カルシウムの粒子の成長を促進させる炭酸カルシウム粒子成長工程は、好ましくは以下のように行う。まず、炭酸カルシウムが水に分散した、炭酸カルシウム水スラリーを用意する。本明細書で炭酸カルシウム水スラリーとは、炭酸カルシウムが水に懸濁または分散した水懸濁液（あるいは水分散体）のことである。炭酸カルシウム水スラリーを得るには、炭酸カルシウムと水とを混合し、撹拌機による撹拌や超音波を利用した撹拌など、従来から行われている方法を適宜行うことができる。また、従来から知られている白石法により製造した炭酸カルシウム水スラリーをそのまま用いることもできる。
　実施形態において、炭酸カルシウムの再結晶を行うにあたり、用意した炭酸カルシウム水スラリーのｐＨをやや低下させて、炭酸カルシウムを溶解させる工程があっても良い。炭酸カルシウム水スラリーのｐＨを低下させるには、たとえば、気体の炭酸カルシウム水スラリーに気体の二酸化炭素を添加すること、あるいは各種酸性物質を添加することにより行うことができる。 In embodiments, the step of growing calcium carbonate particles, which promotes the growth of calcium carbonate particles, is preferably carried out as follows. First, an aqueous calcium carbonate slurry in which calcium carbonate is dispersed in water is prepared. The term "calcium carbonate aqueous slurry" as used herein means an aqueous suspension (or aqueous dispersion) in which calcium carbonate is suspended or dispersed in water. In order to obtain a calcium carbonate aqueous slurry, calcium carbonate and water can be mixed, and a conventional method such as stirring with a stirrer or stirring using ultrasonic waves can be appropriately performed. Moreover, the calcium carbonate aqueous slurry manufactured by the conventionally known Shiraishi method can also be used as it is.
In the embodiment, in recrystallization of calcium carbonate, there may be a step of slightly lowering the pH of the prepared calcium carbonate aqueous slurry to dissolve calcium carbonate. The pH of the aqueous calcium carbonate slurry can be lowered, for example, by adding gaseous carbon dioxide to the gaseous calcium carbonate aqueous slurry, or by adding various acidic substances.
　炭酸カルシウム水スラリーに気体の二酸化炭素を添加する方法は、特に制限されない。撹拌機等を用いて炭酸カルシウム水スラリーを撹拌しながら気体の二酸化炭素を導通させ、炭酸カルシウム水スラリーのｐＨを５．５～１１．０程度に調整することができる。 The method of adding gaseous carbon dioxide to the calcium carbonate aqueous slurry is not particularly limited. The pH of the aqueous calcium carbonate slurry can be adjusted to about 5.5 to 11.0 by passing gaseous carbon dioxide while stirring the aqueous calcium carbonate slurry using a stirrer or the like.
　一方、炭酸カルシウム水スラリーに添加する酸性物質として、炭酸水、塩酸、硫酸、リン酸、臭化水素酸、リン酸、ホウ酸等の無機酸、ベンゼンスルホン酸、酢酸、クエン酸、酒石酸、アスコルビン酸等の有機酸を挙げることができる。これらの酸性物質は、単独で用いても任意の２種以上を用いても良い。炭酸カルシウム水スラリーに添加する酸性物質は、気体、液体、固体のいずれの形状のものでも良いが、液体または固体の状態の酸性物質を添加することが特に好ましい。撹拌機等を用いて炭酸カルシウム水スラリーを撹拌しながら、これらの酸性物質を添加し、炭酸カルシウム水スラリーのｐＨを５．５～１１．０に調整することができる。 On the other hand, as acidic substances added to the calcium carbonate aqueous slurry, inorganic acids such as carbonated water, hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, phosphoric acid, and boric acid, benzenesulfonic acid, acetic acid, citric acid, tartaric acid, and ascorbic acid. Organic acids such as acids can be mentioned. These acidic substances may be used alone or in combination of any two or more. The acidic substance added to the aqueous calcium carbonate slurry may be in the form of gas, liquid or solid, but it is particularly preferred to add the acidic substance in a liquid or solid state. While stirring the calcium carbonate aqueous slurry using a stirrer or the like, these acidic substances can be added to adjust the pH of the calcium carbonate aqueous slurry to 5.5 to 11.0.
　これらの酸性物質が水に溶解して炭酸カルシウム水スラリーが酸性側に傾くことにより、炭酸カルシウムが溶解する。すなわち、炭酸カルシウム水スラリー中に含まれている比較的粒子径の小さい炭酸カルシウムの少なくとも一部は水に溶解する。一方、比較的粒子径の大きい炭酸カルシウムは、少なくともその周囲部が溶解して、粒子径が若干減少した炭酸カルシウムとなる。なお、この段階で、炭酸カルシウムのすべてが溶解してしまわないように、炭酸カルシウム水スラリーのｐＨを調整することが非常に好ましい。 　Calcium carbonate is dissolved by dissolving these acidic substances in water and tilting the calcium carbonate aqueous slurry to the acidic side. That is, at least part of the relatively small particle size calcium carbonate contained in the calcium carbonate aqueous slurry dissolves in water. On the other hand, calcium carbonate with a relatively large particle size dissolves at least in the peripheral portion thereof to become calcium carbonate with a slightly reduced particle size. At this stage, it is very preferable to adjust the pH of the calcium carbonate aqueous slurry so that all of the calcium carbonate does not dissolve.
　実施形態において、炭酸カルシウム水スラリーには、アルカリ環境下でケイ酸イオンを生じる物質を存在させることができる。ここでアルカリ環境下とは、ｐＨが８．０～１４．０の範囲の環境であることを意味する。アルカリ環境下でケイ酸イオンを生じる物質とは、アルカリ性の溶液中で、オルトケイ酸イオン、二ケイ酸イオン、イノケイ酸イオン等の縮合ケイ酸イオン、三員環ソロケイ酸イオン、六員環ソロケイ酸イオン等の環状ケイ酸イオン等を含むケイ酸イオンを生成する物質のことを云う。アルカリ環境下でケイ酸イオンを生じる物質として、たとえば、非晶質シリカ、水ガラス、石英、トリジマイト、クリストバライト、長石、珪藻土およびケイ酸エチルからなる群より選択される物質を挙げることができる。アルカリ環境下でケイ酸イオンを生じる物質は、これらの物質の中から１種以上を用いることができる。アルカリ環境下でケイ酸イオンを生じる物質を炭酸カルシウム水スラリーに添加してから炭酸カルシウム水スラリーのｐＨを５．５～９．０に調整することができ、炭酸カルシウム水スラリーのｐＨを５．５～９．０に調整してからアルカリ環境下でケイ酸イオンを生じる物質を添加することもできる。 In an embodiment, the calcium carbonate aqueous slurry can contain a substance that produces silicate ions in an alkaline environment. Here, the alkaline environment means an environment with a pH in the range of 8.0 to 14.0. Substances that generate silicate ions in an alkaline environment include condensed silicate ions such as orthosilicate ions, disilicate ions, and inosilicate ions, three-membered ring sorosilicate ions, and six-membered ring sorosilicate ions in alkaline solutions. A substance that generates silicate ions, including cyclic silicate ions such as ions. Substances that generate silicate ions in an alkaline environment include, for example, substances selected from the group consisting of amorphous silica, water glass, quartz, tridymite, cristobalite, feldspar, diatomaceous earth and ethyl silicate. One or more of these substances can be used as the substance that generates silicate ions in an alkaline environment. The pH of the aqueous calcium carbonate slurry can be adjusted to 5.5 to 9.0 after adding a substance that generates silicate ions in an alkaline environment to the aqueous calcium carbonate slurry. It is also possible to add a substance that generates silicate ions in an alkaline environment after adjusting to 5 to 9.0.
　アルカリ環境下でケイ酸イオンを生じる物質を炭酸カルシウム水スラリーに添加すると、上記のような炭酸カルシウム水スラリー中に上記のようなケイ酸イオンが存在することになる。ケイ酸イオンは炭酸カルシウム粒子の表面付近に存在し、後述する炭酸カルシウムの粒子の成長を抑制する。炭酸カルシウムの粒子の成長を制御して、所望のＢＥＴ比表面積を有する炭酸カルシウムを得るためには、アルカリ環境下でケイ酸イオンを生じる物質を、炭酸カルシウムの質量に対するケイ素原子の濃度が１００ｐｐｍ以上となるように添加することが非常に好ましい。一般に、炭酸カルシウムの粒子の成長時にケイ酸イオンの濃度が高いと、得られる炭酸カルシウムの粒子径が小さくなり、ケイ酸イオンの濃度が低いと、得られる炭酸カルシウムの粒子径が大きくなる傾向が見られる。そこで、本実施形態では、得られる炭酸カルシウムのＢＥＴ比表面積を制御するために、炭酸カルシウムの質量に対するケイ素原子の濃度が１００ｐｐｍ以上となる範囲で、アルカリ環境下でケイ酸イオンを生じる物質を添加することが好ましい。炭酸カルシウムの質量に対するケイ素原子の濃度は、１００ｐｐｍ以上１０００００ｐｐｍ以下、好ましくは２００ｐｐｍ以上５００００ｐｐｍ以下、さらに好ましくは４００ｐｐｍ以上３００００ｐｐｍ以下とすることができる。 When a substance that generates silicate ions in an alkaline environment is added to the calcium carbonate aqueous slurry, the above silicate ions will be present in the above calcium carbonate aqueous slurry. Silicate ions are present near the surface of calcium carbonate particles and suppress the growth of calcium carbonate particles, which will be described later. In order to control the growth of calcium carbonate particles and obtain calcium carbonate having a desired BET specific surface area, a substance that produces silicate ions in an alkaline environment should be added so that the concentration of silicon atoms relative to the mass of calcium carbonate is 100 ppm or more. It is very preferable to add so that In general, when the concentration of silicate ions is high during the growth of calcium carbonate particles, the particle size of the obtained calcium carbonate tends to be small, and when the concentration of silicate ions is low, the particle size of the obtained calcium carbonate tends to be large. be seen. Therefore, in the present embodiment, in order to control the BET specific surface area of the obtained calcium carbonate, a substance that generates silicate ions in an alkaline environment is added in a range where the concentration of silicon atoms relative to the mass of calcium carbonate is 100 ppm or more. preferably. The concentration of silicon atoms relative to the mass of calcium carbonate can be 100 ppm or more and 100000 ppm or less, preferably 200 ppm or more and 50000 ppm or less, and more preferably 400 ppm or more and 30000 ppm or less.
　次いで、ケイ酸イオンを存在させた炭酸カルシウム水スラリーから炭酸カルシウムの粒子を成長させる。炭酸カルシウムの粒子を成長させるには、炭酸カルシウム水スラリーを静置することにより行う。炭酸カルシウム水スラリーを静置しておくと、先の工程で溶解した炭酸カルシウムが徐々に結晶化していく。この際、炭酸カルシウム水スラリー中に残っていた粒子に集まるように凝集して再結晶していく現象が見られ、略立方体状、略直方体状あるいは略菱面体状の粒子が形成される。
　あるいは、炭酸カルシウム水スラリーのｐＨを徐々に上昇させることにより炭酸カルシウムの粒子を成長させても良い。炭酸カルシウム水スラリーのｐＨを上昇させるには、炭酸カルシウム水スラリーを静置する、炭酸カルシウム水スラリーを撹拌する、炭酸カルシウム水スラリーを減圧する、炭酸カルシウム水スラリーを昇温する、および炭酸カルシウム水スラリーに塩基性物質を添加する等の方法を採り得る。先の工程で添加した酸性物質が二酸化炭素のような気体の場合は、炭酸カルシウム水スラリーを静置しているだけでも徐々に酸性物質が水から蒸発していくため、炭酸カルシウム水スラリーのｐＨは上昇する。このような場合であっても、炭酸カルシウム水スラリーのｐＨをより効率的に上昇させるには、炭酸カルシウム水スラリーを撹拌したり、減圧したり、昇温したり、塩基性物質を添加したりするのが良い。一方、炭酸カルシウム水スラリーに添加した酸性物質が液体または固体の場合は、ｐＨの上昇を促進すべく、炭酸カルシウム水スラリーを撹拌したり、減圧したり、昇温したり、炭酸カルシウム水スラリーに塩基性物質を添加するのが好ましい。炭酸カルシウム水スラリーを緩やかに撹拌しながら、減圧、昇温、塩基性物質の添加等の他の方法を追加で行うことが非常に好ましい。なお炭酸カルシウム水スラリーを昇温させる場合、室温（２５℃）よりは高い温度、具体的には約５０℃～２１０℃、好ましくは約７０℃～１５０℃、さらに好ましくは８０℃～１３０℃の範囲になるように昇温させるのが好ましい。すなわち、炭酸カルシウムの粒子の成長工程全般は、系が５０℃～２１０℃の範囲の温度になるように行うことが好ましい。また炭酸カルシウム水スラリーを減圧する場合、大気圧未満～１０２Ｐａ、好ましくは大気圧未満～１×１０５Ｐａ程度の圧力にまで減圧することが好ましい。また、炭酸カルシウム水スラリーに添加することができる塩基性物質として、アンモニア、水酸化ナトリウム、水酸化マグネシウム、水酸化カルシウム等の無機塩基、アミン類、ピリジン類等の有機塩基およびこれらの組み合わせを挙げることができる。 Next, calcium carbonate particles are grown from the calcium carbonate aqueous slurry in which silicate ions are present. Calcium carbonate particles are allowed to grow by allowing the calcium carbonate aqueous slurry to stand still. When the calcium carbonate aqueous slurry is allowed to stand still, the calcium carbonate dissolved in the previous step gradually crystallizes. At this time, a phenomenon is observed in which the particles remaining in the aqueous calcium carbonate slurry are aggregated and recrystallized, forming approximately cubic, approximately rectangular parallelepiped, or approximately rhombohedral particles.
Alternatively, calcium carbonate particles may be grown by gradually increasing the pH of the calcium carbonate aqueous slurry. In order to raise the pH of the calcium carbonate aqueous slurry, the calcium carbonate aqueous slurry is allowed to stand, the calcium carbonate aqueous slurry is stirred, the calcium carbonate aqueous slurry is depressurized, the calcium carbonate aqueous slurry is heated, and the calcium carbonate aqueous A method such as adding a basic substance to the slurry can be adopted. When the acidic substance added in the previous step is a gas such as carbon dioxide, the acidic substance gradually evaporates from the water even if the calcium carbonate aqueous slurry is left standing still. rises. Even in such a case, in order to increase the pH of the calcium carbonate aqueous slurry more efficiently, the calcium carbonate aqueous slurry is stirred, the pressure is reduced, the temperature is raised, or a basic substance is added. It's good to On the other hand, when the acidic substance added to the calcium carbonate aqueous slurry is liquid or solid, the calcium carbonate aqueous slurry may be stirred, decompressed, or heated to promote the pH increase. It is preferred to add a basic substance. While gently stirring the calcium carbonate aqueous slurry, it is very preferable to additionally perform other methods such as reducing pressure, increasing the temperature, and adding a basic substance. When raising the temperature of the calcium carbonate aqueous slurry, the temperature is higher than room temperature (25°C), specifically about 50°C to 210°C, preferably about 70°C to 150°C, more preferably 80°C to 130°C. It is preferable to raise the temperature so that it falls within the range. That is, it is preferable that the growth process of calcium carbonate particles be carried out in such a manner that the temperature of the system is in the range of 50°C to 210°C. When the calcium carbonate aqueous slurry is decompressed, it is preferably decompressed to a pressure of less than atmospheric pressure to 10 2 Pa, preferably less than atmospheric pressure to about 1×10 5 Pa. Examples of the basic substance that can be added to the aqueous calcium carbonate slurry include inorganic bases such as ammonia, sodium hydroxide, magnesium hydroxide and calcium hydroxide, organic bases such as amines and pyridines, and combinations thereof. be able to.
　炭酸カルシウム水スラリーのｐＨを上昇させる場合、ｐＨは１１．０程度にまで上昇させれば良い。ｐＨを上昇させる過程で、先の工程で溶解した炭酸カルシウムが徐々に結晶化していく。この際、炭酸カルシウム水スラリー中に残っていた粒子に集まるように凝集して再結晶していく現象が見られ、略立方体状、略直方体状あるいは略菱面体状の粒子が形成される。このように炭酸カルシウムの粒子の成長を、ｐＨ８．０～１１．０の間で行うことが重要である。なお、実施形態の製造方法において、炭酸カルシウム水スラリーのｐＨを低下させる工程と、炭酸カルシウム水スラリーのｐＨを上昇させる工程とを繰り返して炭酸カルシウムの粒子を成長させることにより、所望のＢＥＴ比表面積および所望の結晶形を有する炭酸カルシウムを製造することもできる。 When increasing the pH of the calcium carbonate aqueous slurry, the pH should be increased to about 11.0. During the process of raising the pH, the calcium carbonate dissolved in the previous step gradually crystallizes. At this time, a phenomenon is observed in which the particles remaining in the aqueous calcium carbonate slurry are aggregated and recrystallized, forming approximately cubic, approximately rectangular parallelepiped, or approximately rhombohedral particles. Thus, it is important to grow calcium carbonate particles at a pH between 8.0 and 11.0. In the production method of the embodiment, the step of lowering the pH of the aqueous calcium carbonate slurry and the step of raising the pH of the aqueous calcium carbonate slurry are repeated to grow the calcium carbonate particles, thereby obtaining the desired BET specific surface area. and calcium carbonate having the desired crystal form can also be produced.
　本実施形態の方法で製造された炭酸カルシウムは、合成炭酸カルシウムである。上記の通り、炭酸カルシウムは、カルサイト結晶（三方晶系菱面体晶）、アラゴナイト結晶（直方晶系）、バテライト結晶（六方晶）等の結晶多形を有するが、本実施形態で製造される炭酸カルシウムは、カルサイト構造を有することが好ましい。カルサイト結晶は、一般に方解石として産出される結晶の形状であり、他の結晶形と比較すると常温常圧で最も安定である。本実施形態で得られる炭酸カルシウムは、カルサイト構造を有し、ＢＥＴ比表面積は２～５０ｍ２／ｇであることが好ましい。ＢＥＴ比表面積は、物質に、吸着占有面積のわかった気体分子（窒素等）を吸着させ、その量を測定することにより求めることができる。炭酸カルシウムのＢＥＴ比表面積は、日本工業規格ＪＩＳ　Ｚ　８８３０「ガス吸着による粉体（固体）の比表面積測定方法」にしたがい測定することができる。実施形態で得られる炭酸カルシウムのＢＥＴ比表面積は、２～６０ｍ２／ｇであることが好ましく、より好ましくは５～５０ｍ２／ｇ、さらに好ましくは８～４５ｍ２／ｇである。また、実施形態の方法で製造された炭酸カルシウムは、電子顕微鏡で測定した個数基準による平均粒子径が２５ｎｍ～５００ｎｍであることが好ましい。粒子径の測定方法にはいくつかの方法が知られているが、本明細書では、電子顕微鏡を用いて粒子を直接観察および計測し、個数基準による粒子径分布から算出した平均粒子径の値を用いる。平均粒子径が２５～５００ｎｍの炭酸カルシウムとは、ナノオーダーサイズの粒子径の炭酸カルシウム粒子が大部分を占める炭酸カルシウムであることを意味する。実施形態の方法で製造された炭酸カルシウムの平均粒子径は、好ましくは３０～３００ｎｍ、さらに好ましくは３５～２００ｎｍであってよい。 Calcium carbonate produced by the method of the present embodiment is synthetic calcium carbonate. As described above, calcium carbonate has crystal polymorphs such as calcite crystals (trigonal rhombohedral crystals), aragonite crystals (rectangular crystals), and vaterite crystals (hexagonal crystals), but is produced in the present embodiment. Calcium carbonate preferably has a calcite structure. Calcite crystals are generally in the form of crystals produced as calcite, and compared to other crystal forms, they are the most stable at normal temperature and normal pressure. Calcium carbonate obtained in the present embodiment preferably has a calcite structure and a BET specific surface area of 2 to 50 m 2 /g. The BET specific surface area can be determined by allowing a substance to adsorb gas molecules (nitrogen or the like) whose adsorption area is known and measuring the amount. The BET specific surface area of calcium carbonate can be measured according to Japanese Industrial Standard JIS Z 8830 "Method for measuring specific surface area of powder (solid) by gas adsorption". The BET specific surface area of calcium carbonate obtained in the embodiment is preferably 2 to 60 m 2 /g, more preferably 5 to 50 m 2 /g, still more preferably 8 to 45 m 2 /g. In addition, the calcium carbonate produced by the method of the embodiment preferably has a number-based average particle size of 25 nm to 500 nm measured with an electron microscope. Several methods are known for measuring the particle size, but in this specification, the value of the average particle size calculated from the particle size distribution based on number by directly observing and measuring the particles using an electron microscope Use Calcium carbonate having an average particle size of 25 to 500 nm means calcium carbonate in which calcium carbonate particles having a nano-order particle size account for the majority. The average particle size of calcium carbonate produced by the method of the embodiment may be preferably 30-300 nm, more preferably 35-200 nm.
　また、実施形態の方法で製造された炭酸カルシウムは、その一部に、概ね環状の一次粒子を含んでいる場合がある。本明細書において、環状とは、単孔を有する形状全般（リング）および空洞を有する形状全般（ホロー）を指し、円環形状や輪形状のものだけでなく、三角形状や四角形状等、多角形状のものに単孔や空洞を有するもの、および筒状等も含むものとする。さらに本明細書において、概ね環状とは、完全につながった環形状のものだけでなく、一部が途切れてアルファベットのＣの形状になったもの等のように、一部不完全な環形状も含むことを意図する。実施形態の炭酸カルシウムには、その一部に、概ね環状の粒子が含んでいても良い。なお、概ね環状の炭酸カルシウム一次粒子の大きさは、１０～１５０ｎｍ程度である。実施形態で得られる炭酸カルシウムには、概ね環状の一次粒子のほか、球状、略立方体状、略直方体状、略菱面体状、紡錘状、針状等の形状の一次粒子が含まれていても良い。また実施形態の方法で製造される炭酸カルシウムには、球状や略直方体状等の形状の一次粒子の一部が凹んだ形、すなわち孔が完全には空いていないもの等も含まれていて良い。 In addition, the calcium carbonate produced by the method of the embodiment may partially contain primary particles that are generally annular. As used herein, the term “annular” refers to all shapes having a single hole (ring) and all shapes having a cavity (hollow). The shapes include those having a single hole or cavity, and those having a cylindrical shape. Furthermore, in the present specification, the term “generally annular” refers not only to a completely connected ring shape, but also to a partially incomplete ring shape such as a partly broken ring shape such as the letter C shape. intended to include The calcium carbonate of the embodiment may partially contain substantially annular particles. Incidentally, the size of the primary particles of calcium carbonate, which are generally annular, is about 10 to 150 nm. Calcium carbonate obtained in the embodiment may contain primary particles having a shape such as a spherical shape, a substantially cubic shape, a substantially cuboid shape, a substantially rhombohedral shape, a spindle shape, a needle shape, etc. in addition to the substantially annular primary particles. good. In addition, the calcium carbonate produced by the method of the embodiment may include primary particles having a shape such as a spherical shape or a substantially rectangular parallelepiped shape, in which a part of the primary particles is concave, that is, those in which the pores are not completely open. .
　実施形態の方法で製造された炭酸カルシウムは、脂肪酸およびその誘導体、樹脂酸およびその誘導体、シリカ、有機ケイ素化合物、縮合リン酸および縮合リン酸塩からなる群より選択される表面処理剤で表面処理しても良い。ここで脂肪酸として、たとえば、酢酸、酪酸等の低級脂肪酸、パルミチン酸、ステアリン酸、オレイン酸、リノール酸、リノレン酸、アラキドン酸、エイコサペンタエン酸、ドコサヘキサエン酸等の高級脂肪酸が挙げられる。樹脂酸として、アビエチン酸、ネオアビエチン酸、パラストリン酸、ピマル酸、イソピマル酸、デヒドロアビエチン酸等、樹脂由来の酸を挙げることができる。シリカは、組成式ＳｉＯ２で表される化合物（二酸化ケイ素）である。また有機ケイ素化合物として、たとえば、一分子内に有機材料に結合する官能基（ビニル基、エポキシ基、アミノ基、メタクリル基、メルカプト基等）と、無機材料と結合する官能基（メトキシ基、エトキシ基等）とがケイ素原子（Ｓｉ）を介して結合したシランカップリング剤を挙げることができる。縮合リン酸として、オルトリン酸を加熱脱水して得られた無機高分子化合物が挙げられる。これらの表面処理剤は、１つまたは２つ以上を組み合わせて用いることができる。 Calcium carbonate produced by the method of the embodiment is surface-treated with a surface treatment agent selected from the group consisting of fatty acids and derivatives thereof, resin acids and derivatives thereof, silica, organosilicon compounds, condensed phosphoric acid and condensed phosphates. You can Examples of fatty acids include lower fatty acids such as acetic acid and butyric acid, and higher fatty acids such as palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. Examples of resin acids include resin-derived acids such as abietic acid, neoabietic acid, parastric acid, pimaric acid, isopimaric acid, and dehydroabietic acid. Silica is a compound (silicon dioxide) represented by the composition formula SiO2 . As the organic silicon compound, for example, a functional group (vinyl group, epoxy group, amino group, methacrylic group, mercapto group, etc.) that bonds to an organic material and a functional group that bonds to an inorganic material (methoxy group, ethoxy group, etc.) in one molecule. group etc.) are bonded via a silicon atom (Si). Examples of condensed phosphoric acid include inorganic polymer compounds obtained by heating and dehydrating orthophosphoric acid. These surface treatment agents can be used singly or in combination of two or more.
　実施形態の方法で製造された炭酸カルシウム、樹脂等と混合して樹脂組成物を製造することに用いられる。炭酸カルシウムは、無機フィラーとして従来用いられている硫酸バリウムや酸化チタン等と比較して比重が小さい。このため、無機フィラーとして炭酸カルシウムを用いることにより、樹脂組成物を軽量化することができる。樹脂は、ポリオレフィン樹脂、ポリエステル樹脂組成物、ポリアリレート樹脂組成物、各種ジエン系樹脂等のエラストマー樹脂およびこれらの混合物からなる群より選択されることが好ましい。ポリオレフィン樹脂、ポリ塩化ビニル樹脂、ポリエステル樹脂、ポリアリレート樹脂およびジエン系樹脂等のエラストマー樹脂は、それぞれ単独で、またはこれらを組み合わせて用いることができる。また、本発明の目的を損なわない範囲で、ポリオレフィン樹脂、ポリエステル樹脂、ポリアリレート樹脂、ジエン系樹脂等のエラストマー樹脂およびこれらの混合物以外の樹脂を必要に応じて含むこともできる。 It is used to produce a resin composition by mixing with calcium carbonate, resin, etc. produced by the method of the embodiment. Calcium carbonate has a smaller specific gravity than barium sulfate, titanium oxide, and the like, which have been conventionally used as inorganic fillers. Therefore, the weight of the resin composition can be reduced by using calcium carbonate as the inorganic filler. The resin is preferably selected from the group consisting of polyolefin resins, polyester resin compositions, polyarylate resin compositions, elastomer resins such as various diene resins, and mixtures thereof. Elastomer resins such as polyolefin resins, polyvinyl chloride resins, polyester resins, polyarylate resins and diene resins may be used alone or in combination. In addition, resins other than elastomer resins such as polyolefin resins, polyester resins, polyarylate resins, diene resins, and mixtures thereof may be included as necessary within a range that does not impair the object of the present invention.
　ポリオレフィン樹脂とは、オレフィン（アルケン）または環状オレフィン単量体を重合させた単独重合体、共重合体、およびこれらの混合物のことである。ポリオレフィン樹脂として、たとえば、ポリエチレン、ポリプロピレン、ポリ４－メチルペンテン－１、ポリブテン－１、ポリ１－ヘキセン、エチレン－テトラシクロドデセン共重合体、ポリアセタールが挙げられる。また、ポリ塩化ビニル（ＰＶＣ）樹脂は、塩化ビニルモノマーの単独重合体あるいは塩化ビニルモノマーと共重合可能な他のモノマーとの共重合体を用いることができる。ここで塩化ビニルモノマーと共重合体を形成しうる他のモノマーとしては、たとえば、酢酸ビニル、プロピオン酸ビニル、ステアリン酸ビニルなどのビニルエステル類；ジエチルマレエート、ジブチルマレエートなどのマレイン酸エステル類；ジエチルフマレート、ジブチルフマレートなどのフマル酸エステル類；アクリル酸エステル類；メタクリル酸エステル類；ビニルメチルエーテルなどのビニルエーテル類を挙げることができる。このようなＰＶＣ樹脂として、ＰＶＣゾル、硬質ＰＶＣ、あるいは軟質ＰＶＣを用いることができる。ポリエステル樹脂とは、多価カルボン酸とポリオールとの重縮合物からなるポリエステル類およびこれらの混合物である。ポリエステル樹脂としては、芳香族ポリエステル樹脂が好ましく用いられる。芳香族ポリエステル樹脂としては、たとえば、ポリメチレンテレフタレート樹脂（ＰＴＴ）、ポリエチレンテレフタレート樹脂（ＰＥＴ）、ポリプロピレンテレフタレート樹脂、ポリブチレンテレフタレート樹脂（ＰＢＴ）、ポリエチレンナフタレート樹脂（ＰＥＮ）、ポリブチレンナフタレート樹脂（ＰＢＮ）、ポリ（シクロヘキサン－１，４－ジメチレン－テレフタレート）樹脂、ポリトリメチレンテレフタレート樹脂が挙げられる。さらに、アルキレンテレフタレート構成単位を主構成単位とするアルキレンテレフタレートコポリマーや、ポリアルキレンテレフタレートを主成分とするポリアルキレンテレフタレート混合物を挙げることができる。さらに、ポリオキシテトラメチレングリコール（ＰＴＭＧ）等のエラストマー成分を含有又は共重合したものを用いてもよい。ポリアルキレンテレフタレートの混合物としては、たとえば、ＰＢＴとＰＢＴ以外のポリアルキレンテレフタレートとの混合物、ＰＢＴとＰＢＴ以外のアルキレンテレフタレートコポリエステルとの混合物が挙げられる。なかでも、ＰＢＴとＰＥＴとの混合物や、ＰＢＴとポリトリメチレンテレフタレートとの混合物、ＰＢＴとＰＢＴ／ポリアルキレンイソフタレートとの混合物などが好ましい。ジエン系のエラストマー樹脂として、ポリブタジエン、ポリイソプレン、ポリクロロプレン等のジエン系モノマーを重合して得たゴム材料が挙げられる。またウレタンゴム、シリコーンゴム、フッ素ゴム等のエラストマー樹脂を用いても良い。その他、実施形態の製造方法で得られる炭酸カルシウムは、変性シリコーン樹脂、ポリウレタン樹脂、ポリサルファイド樹脂、アクリルゾル、ロジン変性アルキド樹脂、各種のアクリレート樹脂の他、前記の樹脂を含む樹脂混合物や塗料組成物、たとえば、アクリル樹脂塗料、ポリウレタン樹脂塗料、アクリルシリコーン樹脂塗料またはフッ素樹脂塗料に添加することができる。 Polyolefin resins are homopolymers, copolymers, and mixtures thereof obtained by polymerizing olefin (alkene) or cyclic olefin monomers. Examples of polyolefin resins include polyethylene, polypropylene, poly-4-methylpentene-1, polybutene-1, poly-1-hexene, ethylene-tetracyclododecene copolymer, and polyacetal. As the polyvinyl chloride (PVC) resin, a homopolymer of a vinyl chloride monomer or a copolymer of a vinyl chloride monomer and another monomer that can be copolymerized can be used. Other monomers capable of forming copolymers with vinyl chloride monomers include, for example, vinyl esters such as vinyl acetate, vinyl propionate and vinyl stearate; maleate esters such as diethyl maleate and dibutyl maleate. fumaric acid esters such as diethyl fumarate and dibutyl fumarate; acrylic acid esters; methacrylic acid esters; and vinyl ethers such as vinyl methyl ether. PVC sol, hard PVC, or soft PVC can be used as such a PVC resin. Polyester resins are polyesters composed of polycondensates of polyvalent carboxylic acids and polyols, and mixtures thereof. As the polyester resin, an aromatic polyester resin is preferably used. Examples of aromatic polyester resins include polymethylene terephthalate resin (PTT), polyethylene terephthalate resin (PET), polypropylene terephthalate resin, polybutylene terephthalate resin (PBT), polyethylene naphthalate resin (PEN), polybutylene naphthalate resin ( PBN), poly(cyclohexane-1,4-dimethylene-terephthalate) resins, polytrimethylene terephthalate resins. Furthermore, alkylene terephthalate copolymers containing alkylene terephthalate structural units as main structural units and polyalkylene terephthalate mixtures containing polyalkylene terephthalate as a main component can be mentioned. Further, one containing or copolymerizing an elastomer component such as polyoxytetramethylene glycol (PTMG) may be used. Mixtures of polyalkylene terephthalates include, for example, mixtures of PBT and polyalkylene terephthalates other than PBT, and mixtures of PBT and alkylene terephthalate copolyesters other than PBT. Among them, a mixture of PBT and PET, a mixture of PBT and polytrimethylene terephthalate, a mixture of PBT and PBT/polyalkyleneisophthalate, and the like are preferable. Examples of diene-based elastomer resins include rubber materials obtained by polymerizing diene-based monomers such as polybutadiene, polyisoprene, and polychloroprene. Elastomer resins such as urethane rubber, silicone rubber, and fluororubber may also be used. In addition, the calcium carbonate obtained by the production method of the embodiment can be used in modified silicone resins, polyurethane resins, polysulfide resins, acrylic sols, rosin-modified alkyd resins, various acrylate resins, as well as resin mixtures and coating compositions containing the above resins. For example, it can be added to acrylic resin paints, polyurethane resin paints, acrylic silicone resin paints, or fluorine resin paints.
　実施形態の方法で製造された炭酸カルシウムを充填材として用いる場合、単独で用いることが最も好ましいが、必要に応じて、硫酸バリウム、酸化チタン、タルク等の従来から用いられている無機フィラーを混合することもできる。なお、実施形態の炭酸カルシウムを含む樹脂組成物は、通常の添加剤、たとえば、酸化防止剤、可塑剤、熱安定剤、紫外線吸収剤、繊維状強化剤、滑剤、難燃剤、帯電防止剤、着色剤、顔料を含有することができる。特に、可塑剤は、一般にＰＶＣゾル組成物に使用されるものを用いることができ、ジ－ｎ－オクチルフタレート（ＤＯＰ）、ジ－２－エチルヘキシルフタレート、ジイソノニルフタレート（ＤＩＮＰ）等のフタル酸系可塑剤；ジ－２－エチルヘキシルアジペート（ＤＯＡ）、トリメリット酸トリス－２－エチルヘキシル（ＴＯＴＭ）、アゼライン酸、セバシン酸等とのエステル化合物を含む脂肪族エステル系可塑剤；リン酸、トリクレジルホスフェート等のリン酸エステル系可塑剤；エポキシ化大豆油等のエポキシ系可塑剤を用いることができ、これらの１種または２種以上を混合して用いることもできる。そして可塑剤の使用量は、プラスチゾルの粘度、硬化性、硬化後の硬度、安定性などの物性により適宜選択され、一般に、ＰＶＣ樹脂１００質量部に対して３０～３００質量部の範囲で使用されることが好ましい。なお、可塑剤以外の添加剤の含量は、樹脂組成物の１０質量％以下であることが好ましい。 When calcium carbonate produced by the method of the embodiment is used as a filler, it is most preferable to use it alone, but if necessary, conventionally used inorganic fillers such as barium sulfate, titanium oxide, and talc are mixed. You can also In addition, the resin composition containing calcium carbonate of the embodiment contains ordinary additives such as antioxidants, plasticizers, heat stabilizers, ultraviolet absorbers, fibrous reinforcing agents, lubricants, flame retardants, antistatic agents, Colorants and pigments can be contained. In particular, plasticizers generally used in PVC sol compositions can be used, and phthalic acid-based plasticizers such as di-n-octyl phthalate (DOP), di-2-ethylhexyl phthalate, and diisononyl phthalate (DINP) can be used. Agent: Di-2-ethylhexyl adipate (DOA), tris-2-ethylhexyl trimellitate (TOTM), azelaic acid, aliphatic ester plasticizer including ester compounds with sebacic acid; phosphoric acid, tricresyl phosphate Phosphate plasticizers such as phosphate ester plasticizers; and epoxy plasticizers such as epoxidized soybean oil can be used, and one or more of these can be used in combination. The amount of the plasticizer to be used is appropriately selected according to physical properties such as viscosity, curability, hardness after curing, and stability of the plastisol. preferably. The content of additives other than the plasticizer is preferably 10 mass % or less of the resin composition.
　上記の通り、実施形態の方法で製造された炭酸カルシウムは、その一部に概ね環状の一次粒子が含まれていても良い。概ね環状の一次粒子が含まれた炭酸カルシウムを、そのまま用いることができるほか、概ね環状の一次粒子を選択的に分離することもまた可能である。概ね環状の一次粒子の分離は、たとえば、篩いにかけて特定の範囲の粒子径の炭酸カルシウム粒子を取り出し、ついで顕微鏡観察により概ね環状の一次粒子のみを分離することで行うことができる。 As described above, the calcium carbonate produced by the method of the embodiment may partially contain substantially annular primary particles. Calcium carbonate containing substantially annular primary particles can be used as it is, and it is also possible to selectively separate the substantially annular primary particles. Separation of the substantially annular primary particles can be carried out, for example, by sieving to extract calcium carbonate particles having a particle size within a specific range, and then separating only the substantially annular primary particles by microscopic observation.
　上記の通り、実施形態の方法で製造される炭酸カルシウムは、各種樹脂と混合して樹脂組成物として使用できる。炭酸カルシウムは樹脂の無機フィラーとして使用するほか、紙、塗料、インキ等の填料として使用可能である。さらに食品、化粧品等の充填材としての使用もできる。分離操作を行い得られた概ね環状の炭酸カルシウムは、その特殊な形状を利用して、たとえば、ナノ材料の鋳型、薬剤担体、触媒担体、軽量フィラーとして用いることが期待できる。 As described above, the calcium carbonate produced by the method of the embodiment can be mixed with various resins and used as a resin composition. In addition to being used as an inorganic filler for resins, calcium carbonate can also be used as a filler for paper, paint, ink, and the like. Furthermore, it can also be used as a filler for foods, cosmetics and the like. The approximately cyclic calcium carbonate obtained by the separation operation can be expected to be used, for example, as a template for nanomaterials, a drug carrier, a catalyst carrier, and a lightweight filler by utilizing its special shape.
　以下に本発明の実施形態を具体的に説明する。本発明はその要旨を超えない限り、以下の実施例に限定されるものではない。 The embodiments of the present invention will be specifically described below. The present invention is not limited to the following examples as long as the gist thereof is not exceeded.
［実施例１：本発明による炭酸カルシウムの製造］
　［ケイ酸イオンの存在する炭酸カルシウム水スラリーの調製］
　水酸化カルシウムのスラリーに炭酸ガスを導入して炭酸カルシウム粒子を得た。得られた炭酸カルシウムのＢＥＴ比表面積は、３５．６ｍ２／ｇ（日本工業規格ＪＩＳ　Ｚ　８８３０）、電子顕微鏡で測定した個数基準による平均粒子径は４４ｎｍ（結晶子サイズは５１ｎｍ）であった。得られた炭酸カルシウムの水スラリー（炭酸カルシウム水スラリー、固形分含量１０重量％、ｐＨ６．８）に、炭酸カルシウムの質量に対するケイ素原子の濃度が４６０ｐｐｍとなるように非晶質シリカ（株式会社高純度化学研究所）を添加した。非晶質シリカを添加した炭酸カルシウム水スラリーを緩やかに撹拌しながら、ビーカーを加熱し、温度を９５℃にした。炭酸カルシウム水スラリーの撹拌を続け、そのまま６時間エージングを行った。エージング後の炭酸カルシウム水スラリーのｐＨは１０．１であった。この炭酸カルシウム水スラリーに脂肪酸石鹸（製品名：タンカルＭＨ、会社名：ミヨシ油脂株式会社）を投入し、炭酸カルシウムの表面処理を行った。その後、脱水、乾燥および粉砕を行い、炭酸カルシウム粉末を得た。 [Example 1: Production of calcium carbonate according to the present invention]
[Preparation of aqueous calcium carbonate slurry containing silicate ions]
Carbon dioxide gas was introduced into the slurry of calcium hydroxide to obtain calcium carbonate particles. The BET specific surface area of the obtained calcium carbonate was 35.6 m 2 /g (Japanese Industrial Standard JIS Z 8830), and the number-based average particle size measured with an electron microscope was 44 nm (crystallite size was 51 nm). Amorphous silica (Takashi Co., Ltd. Pure Chemical Laboratory) was added. The beaker was heated to a temperature of 95° C. while gently stirring the calcium carbonate aqueous slurry containing amorphous silica. Stirring of the aqueous calcium carbonate slurry was continued, and aging was performed for 6 hours. The pH of the calcium carbonate aqueous slurry after aging was 10.1. A fatty acid soap (product name: Tancal MH, company name: Miyoshi Oil & Fat Co., Ltd.) was added to this calcium carbonate water slurry to surface-treat the calcium carbonate. Thereafter, dehydration, drying and pulverization were performed to obtain calcium carbonate powder.
　［炭酸カルシウム水スラリーの処理］
　炭酸カルシウム水スラリーをエタノールで洗浄して、減圧濾過し、真空乾燥させて白色固体の状態の炭酸カルシウムを得た（日本工業規格ＪＩＳ　Ｚ　８８３０に従い測定したＢＥＴ比表面積：１３．５ｍ２／ｇ、結晶子サイズ：１０５ｎｍ）。得られた炭酸カルシウムをエタノールに分散させ、カーボン補強コロジオン支持膜付き銅グリッドに滴下し、エタノールを乾燥させ、真空乾燥を行い、透過型電子顕微鏡（ＴＥＭ）用試料を作製した。試料を電子顕微鏡（装置名：日本電子株式会社　ＪＥＭ－２１００）で観察した（図１）。 [Treatment of calcium carbonate aqueous slurry]
The calcium carbonate aqueous slurry was washed with ethanol, filtered under reduced pressure, and dried in vacuo to obtain calcium carbonate in the state of white solid (BET specific surface area measured according to Japanese Industrial Standard JIS Z 8830: 13.5 m 2 /g, Crystallite size: 105 nm). The resulting calcium carbonate was dispersed in ethanol, dropped onto a copper grid with a carbon-reinforced collodion support film, ethanol was dried, and vacuum drying was performed to prepare a sample for a transmission electron microscope (TEM). The sample was observed with an electron microscope (device name: JEOL Ltd. JEM-2100) (Fig. 1).
　［実施例２－６］
　実施例１において、炭酸カルシウム水スラリーに添加する非晶質シリカの量を、炭酸カルシウムの質量に対するケイ素原子の濃度が１９００ｐｐｍとなるように加え、エージングをｐＨ１０．０になるまで行ったこと以外は実施例１を繰り返した（実施例２）。ＢＥＴ比表面積１４．９ｍ２／ｇ、結晶子サイズ９７ｎｍの炭酸カルシウムが得られた（図２）。
　実施例１において、炭酸カルシウム水スラリーに添加する非晶質シリカの量を、炭酸カルシウムの質量に対するケイ素原子の濃度が７８００ｐｐｍとなるように加え、エージングをｐＨ８．９になるまで行ったこと以外は実施例１を繰り返した（実施例３）。ＢＥＴ比表面積１９．１ｍ２／ｇ、結晶子サイズ８０ｎｍの炭酸カルシウムが得られた（図３）。
　実施例１において、炭酸カルシウム水スラリーに添加する非晶質シリカの量を、炭酸カルシウムの質量に対するケイ素原子の濃度が３１０００ｐｐｍとなるように加え、エージングをｐＨ８．６になるまで行ったこと以外は実施例１を繰り返した（実施例４）。ＢＥＴ比表面積２０．２ｍ２／ｇ、結晶子サイズ７７ｎｍの炭酸カルシウムが得られた（図４）。
　実施例１において、炭酸カルシウム水スラリーに添加する物質を水ガラス（セントラル硝子株式会社）に変え、炭酸カルシウムの質量に対するケイ素原子の濃度が１９００ｐｐｍとなるように加え、エージングをｐＨ１０．９になるまで行ったこと以外は実施例１を繰り返した（実施例５）。ＢＥＴ比表面積１４．６ｍ２／ｇ、結晶子サイズ９８ｎｍの炭酸カルシウムが得られた。
　実施例１において、炭酸カルシウム水スラリーに添加する非晶質シリカの量を、炭酸カルシウムの質量に対するケイ素原子の濃度が１９００ｐｐｍとなるように加え、エージング時の温度を６０℃とし、エージングをｐＨ１０．７になるまで行ったこと以外は実施例１を繰り返した（実施例６）。ＢＥＴ比表面積１３．６ｍ２／ｇ、結晶子サイズ１０５ｎｍの炭酸カルシウムが得られた。 [Example 2-6]
In Example 1, the amount of amorphous silica added to the calcium carbonate aqueous slurry was added so that the concentration of silicon atoms with respect to the mass of calcium carbonate was 1900 ppm, and aging was performed until the pH reached 10.0. Example 1 was repeated (Example 2). Calcium carbonate with a BET specific surface area of 14.9 m 2 /g and a crystallite size of 97 nm was obtained (Fig. 2).
In Example 1, the amount of amorphous silica added to the calcium carbonate aqueous slurry was added so that the concentration of silicon atoms with respect to the mass of calcium carbonate was 7800 ppm, and aging was performed until the pH reached 8.9. Example 1 was repeated (Example 3). Calcium carbonate with a BET specific surface area of 19.1 m 2 /g and a crystallite size of 80 nm was obtained (Fig. 3).
In Example 1, the amount of amorphous silica added to the calcium carbonate aqueous slurry was added so that the concentration of silicon atoms with respect to the mass of calcium carbonate was 31000 ppm, and aging was performed until the pH reached 8.6. Example 1 was repeated (Example 4). Calcium carbonate with a BET specific surface area of 20.2 m 2 /g and a crystallite size of 77 nm was obtained (Fig. 4).
In Example 1, the substance added to the calcium carbonate aqueous slurry was changed to water glass (Central Glass Co., Ltd.), added so that the concentration of silicon atoms relative to the mass of calcium carbonate was 1900 ppm, and aged to pH 10.9. Example 1 was repeated except what was done (Example 5). Calcium carbonate with a BET specific surface area of 14.6 m 2 /g and a crystallite size of 98 nm was obtained.
In Example 1, the amount of amorphous silica added to the calcium carbonate aqueous slurry was such that the concentration of silicon atoms relative to the mass of calcium carbonate was 1900 ppm, the temperature during aging was 60°C, and the aging was carried out at pH 10.0. Example 1 was repeated except that it went to 7 (Example 6). Calcium carbonate with a BET specific surface area of 13.6 m 2 /g and a crystallite size of 105 nm was obtained.
　［比較例１－４］
　実施例１において、非晶質シリカを添加しなかったこと以外は実施例１を繰り返した（比較例１）。ＢＥＴ比表面積１２．４ｍ２／ｇ、結晶子サイズ１１４ｎｍの炭酸カルシウムが得られた（図５）。
　実施例１において、非晶質シリカを添加せず、エージング時間を２時間とし、エージングをｐＨ１２になるまで行ったこと以外は実施例１を繰り返した（比較例２）。ＢＥＴ比表面積１９．５ｍ２／ｇ、結晶子サイズ８２ｎｍの炭酸カルシウムが得られた。
　実施例１において、非晶質シリカを添加せず、エージング時間を１時間とし、エージングをｐＨ１２になるまで行ったこと以外は実施例１を繰り返した（比較例３）。ＢＥＴ比表面積２１．０ｍ２／ｇ、結晶子サイズ８０ｎｍの炭酸カルシウムが得られた。
　比較例１で得られた炭酸カルシウムと、比較例１において、エージングを行う前の炭酸カルシウムとを混合した（比較例４）。ＢＥＴ比表面積２０．２ｍ２／ｇ、結晶子サイズ８５ｎｍの炭酸カルシウムが得られた。
　実施例１において、非晶質シリカを添加せず、エージング時間を０．５時間としたこと以外は実施例１を繰り返した（比較例５）。ＢＥＴ比表面積２５．２ｍ２／ｇ、結晶子サイズ７１ｎｍの炭酸カルシウムが得られた。 [Comparative Example 1-4]
Example 1 was repeated except that in Example 1 no amorphous silica was added (Comparative Example 1). Calcium carbonate with a BET specific surface area of 12.4 m 2 /g and a crystallite size of 114 nm was obtained (Fig. 5).
Example 1 was repeated except that no amorphous silica was added, the aging time was 2 hours, and the aging was carried out to pH 12 (Comparative Example 2). Calcium carbonate with a BET specific surface area of 19.5 m 2 /g and a crystallite size of 82 nm was obtained.
Example 1 was repeated except that no amorphous silica was added, the aging time was 1 hour, and the aging was performed until pH 12 (Comparative Example 3). Calcium carbonate having a BET specific surface area of 21.0 m 2 /g and a crystallite size of 80 nm was obtained.
The calcium carbonate obtained in Comparative Example 1 was mixed with the calcium carbonate before aging in Comparative Example 1 (Comparative Example 4). Calcium carbonate with a BET specific surface area of 20.2 m 2 /g and a crystallite size of 85 nm was obtained.
Example 1 was repeated except that no amorphous silica was added and the aging time was 0.5 hours (Comparative Example 5). Calcium carbonate with a BET specific surface area of 25.2 m 2 /g and a crystallite size of 71 nm was obtained.
　［炭酸カルシウム充填ポリ塩化ビニルゾルの調製と粘性の測定］
　実施例１－６および比較例１－５で得られた各表面処理炭酸カルシウムを用いて、ポリ塩化ビニル（ＰＶＣ）ゾルを調製した。
　ＰＶＣゾルは、各表面処理炭酸カルシウム２００ｇ、ＰＶＣ樹脂（商品名「ＺＥＳＴ　Ｐ２１」、新第一塩ビ株式会社）３００ｇ、可塑剤としてフタル酸ジイソノニル（ＤＩＮＰ）３００ｇ、重質炭酸カルシウム（商品名「ホワイトンＰ－３０」、白石工業株式会社）１５０ｇ、接着付与剤（商品名「バーサミド１４０」、ヘンケルジャパン）１０ｇ、および希釈剤（商品名「ミネラルターペン」、山桂産業株式会社）４０ｇを十分に混練して調製した。各ＰＶＣゾルの粘度を測定した。 [Preparation of calcium carbonate-filled polyvinyl chloride sol and measurement of viscosity]
A polyvinyl chloride (PVC) sol was prepared using each surface-treated calcium carbonate obtained in Examples 1-6 and Comparative Examples 1-5.
The PVC sol consists of 200 g of each surface-treated calcium carbonate, 300 g of PVC resin (trade name “ZEST P21”, Shin-Daiichi PVC Co., Ltd.), 300 g of diisononyl phthalate (DINP) as a plasticizer, and heavy calcium carbonate (trade name “White P-30", Shiraishi Kogyo Co., Ltd.) 150 g, tackifier (trade name "Versamide 140", Henkel Japan) 10 g, and diluent (trade name "Mineral Turpen", Sankei Sangyo Co., Ltd.) 40 g Prepared by kneading. The viscosity of each PVC sol was measured.
　［炭酸カルシウム充填ポリ塩化ビニル樹脂組成物の調製と粘性の測定］
　実施例１－６および比較例１－５で得られた各表面処理炭酸カルシウムを用いて、ポリ塩化ビニル（ＰＶＣ）樹脂組成物を調製した。各成分の組成は以下の通り：
　・塩化ビニル樹脂（商品名「カネビニルＳ－１００１」、株式会社カネカ）：１００質量部
　・コアシェル重合体組成物（商品名「カネエースＦＭ－４０」、白色樹脂粉末、株式会社カネカ）：３．５質量部
　・実施例、比較例で得られた各表面処理炭酸カルシウム：１０質量部
　・有機錫系安定剤（商品名「ＴＭ－１８１ＦＳＪ」、メチル錫メルカプト系安定剤、勝田化工株式会社）１．５質量部
　・パラフィンワックス（商品名「Ｒｈｅｏｌｕｂ１６５」、Ｒｈｅｏｃｈｅｍ社）：１．０質量部
　・ステアリン酸カルシウム（商品名「ＳＣ－１００」、堺化学工業株式会社）：１．２質量部
　・酸化ポリエチレンワックス（商品名「ＡＣＰＥ－６２９Ａ」、アライドシグナル社）：０．１質量部
　・酸化チタン（商品名「ＴＩＴＯＮ　Ｒ－６２Ｎ」、堺化学工業株式会社）：１０質量部
　・加工助剤（商品名「カネエースＰＡ－２０」、株式会社カネカ）：１．５質量部
　上記各原料を、ヘンシェルミキサーでブレンドして原料混合物を得た。得られた原料混合物を、２０ｍｍ同方向二軸押出機を用いて、押出温度１７０℃、スクリュー回転数１００ｒｐｍ、吐出量５ｋｇ／ｈｒの条件にて混練し、塩化ビニル系樹脂組成物のペレットを得た。
　得られたペレットを用いて、型締め力７５トンの射出成形機で成形体を作製した。シャルピー衝撃強さを測定するための成形体は、ＩＳＯ－Ａの金型を用いて、厚み４ｍｍの試験片を得た。耐候性試験に用いる成形体は、ＩＳＯ－Ｄ２の金型を用いて、厚み２ｍｍ、縦５０ｍｍ×横５０ｍｍのプレート状の成形体を得た。 [Preparation of calcium carbonate-filled polyvinyl chloride resin composition and measurement of viscosity]
A polyvinyl chloride (PVC) resin composition was prepared using each surface-treated calcium carbonate obtained in Examples 1-6 and Comparative Examples 1-5. The composition of each component is as follows:
・ Vinyl chloride resin (trade name “Kanevinyl S-1001”, Kaneka Co., Ltd.): 100 parts by mass ・ Core-shell polymer composition (trade name “Kane Ace FM-40”, white resin powder, Kaneka Co., Ltd.): 3.5 Parts by mass Each surface-treated calcium carbonate obtained in Examples and Comparative Examples: 10 parts by mass Organic tin stabilizer (trade name “TM-181FSJ”, methyltin mercapto stabilizer, Katsuta Kako Co., Ltd.)1. 5 parts by mass ・Paraffin wax (trade name “Rheolub 165”, Rheochem): 1.0 parts by mass ・Calcium stearate (trade name “SC-100”, Sakai Chemical Industry Co., Ltd.): 1.2 parts by mass ・Polyethylene oxide wax (trade name "ACPE-629A", Allied Signal): 0.1 parts by mass ・Titanium oxide (trade name "TITON R-62N", Sakai Chemical Industry Co., Ltd.): 10 parts by mass ・Processing aid (trade name " Kane Ace PA-20", Kaneka Corporation): 1.5 parts by mass The above raw materials were blended in a Henschel mixer to obtain a raw material mixture. The resulting raw material mixture is kneaded using a 20 mm co-rotating twin-screw extruder under the conditions of an extrusion temperature of 170° C., a screw rotation speed of 100 rpm, and a discharge rate of 5 kg/hr to obtain pellets of a vinyl chloride resin composition. rice field.
Using the obtained pellets, a molded article was produced with an injection molding machine having a clamping force of 75 tons. A molded body for measuring the Charpy impact strength was obtained using an ISO-A mold to obtain a test piece having a thickness of 4 mm. For the molded body used in the weather resistance test, a mold of ISO-D2 was used to obtain a plate-shaped molded body having a thickness of 2 mm, a length of 50 mm and a width of 50 mm.
　［シャルピー衝撃強さの測定］
　上記で得られた炭酸カルシウム充填ＰＶＣ樹脂組成物成形体のシャルピー衝撃強さは、ＩＳＯ１７９－１および－２に準拠してノッチ付きで行った。強さの単位は、ｋＪ／ｍ２を採用した。 [Measurement of Charpy impact strength]
The Charpy impact strength of the calcium carbonate-filled PVC resin composition molded article obtained above was measured with a notch according to ISO179-1 and -2. The unit of strength is kJ/ m2 .
　一方カルシウム充填ＰＶＣ樹脂組成物のＢ型回転粘度（２ｒｐｍおよび２０ｒｐｍ）を
　　の方法で測定し、２つの回転粘度の比（チキソトロピックインデックス（ＴＩ））を求めた。
Figure JPOXMLDOC01-appb-T000001
  
Figure JPOXMLDOC01-appb-T000002
   On the other hand, the B-type rotational viscosities (2 rpm and 20 rpm) of the calcium-filled PVC resin composition were measured by the method described above to determine the ratio of the two rotational viscosities (thixotropic index (TI)).
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
　アルカリ環境下でケイ酸イオンを生じる物質（非晶質シリカ）の存在下で炭酸カルシウムの結晶成長を行う本発明の方法で製造された炭酸カルシウムは、ＰＶＣに混合した際にチキソ性が高く、衝撃強さの大きいＰＶＣ樹脂組成物を提供することができる。実施例で得られた炭酸カルシウムと比較例で得られた炭酸カルシウムのＢＥＴ比表面積を比較すると分かる通り、本発明の製造方法によると、エージング時間の割に比較的粒子径の小さい炭酸カルシウムを得ることができる。炭酸カルシウムの結晶成長環境下にケイ酸イオンが存在すると、炭酸カルシウムの結晶成長がやや抑制され、大きな粒子になりにくいと考えられる。
  Calcium carbonate produced by the method of the present invention in which calcium carbonate crystals grow in the presence of a substance (amorphous silica) that produces silicate ions in an alkaline environment exhibits high thixotropic properties when mixed with PVC. A PVC resin composition having high impact strength can be provided. As can be seen from a comparison of the BET specific surface areas of the calcium carbonate obtained in Examples and the calcium carbonate obtained in Comparative Examples, according to the production method of the present invention, calcium carbonate having a relatively small particle size can be obtained in spite of the aging time. be able to. Presumably, the presence of silicate ions in the environment for crystal growth of calcium carbonate somewhat inhibits the crystal growth of calcium carbonate, making it difficult for the particles to form large particles.

Claims (4)

  1. 　炭酸カルシウム水スラリーを原料として、炭酸カルシウムの粒子の成長を促進させる炭酸カルシウム粒子成長工程を少なくとも含む、炭酸カルシウムの製造方法であって、
    　該炭酸カルシウム粒子成長工程において、アルカリ環境下でケイ酸イオンを生じる物質を該炭酸カルシウム水スラリー中に添加することを特徴とする、前記炭酸カルシウムの製造方法。     A method for producing calcium carbonate, comprising at least a step of growing calcium carbonate particles by using an aqueous calcium carbonate slurry as a raw material and promoting the growth of calcium carbonate particles,
    The method for producing calcium carbonate, wherein in the step of growing calcium carbonate particles, a substance that generates silicate ions in an alkaline environment is added to the aqueous calcium carbonate slurry.
  2. 　該炭酸カルシウム粒子成長工程において、該物質を、炭酸カルシウムの質量に対するケイ素原子の濃度が１００ｐｐｍ以上となるように添加する、請求項１に記載の製造方法。 The production method according to claim 1, wherein in the calcium carbonate particle growth step, the substance is added so that the concentration of silicon atoms relative to the mass of calcium carbonate is 100 ppm or more.
  3. 　該物質が、非晶質シリカ、水ガラス、石英、トリジマイト、クリストバライト、長石、珪藻土およびケイ酸エチルからなる群より選択される１種以上である、請求項１または２に記載の製造方法。 The production method according to claim 1 or 2, wherein the substance is one or more selected from the group consisting of amorphous silica, water glass, quartz, tridymite, cristobalite, feldspar, diatomaceous earth and ethyl silicate.
  4. 　該炭酸カルシウム粒子成長工程が、５０～２１０℃の温度で行われる、請求項１～３のいずれか１項に記載の製造方法。 The production method according to any one of claims 1 to 3, wherein the calcium carbonate particle growth step is performed at a temperature of 50 to 210°C.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050170178A1 (en) * 2002-03-20 2005-08-04 Jianfeng Chen CaCO3/SiO2.nH2O nanocomposite particles and SiO2.nH2O hollow-structures nanomaterials and synthesizing method
JP2005281925A (en) * 2004-03-30 2005-10-13 Nippon Paper Industries Co Ltd Neutral paper for printing newspaper
JP2021507863A (en) * 2017-12-12 2021-02-25 イメルテック ソシエテ パル アクシオン サンプリフィエ Preparation of silica-coated calcium carbonate with increased surface area and mesoporous properties

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050170178A1 (en) * 2002-03-20 2005-08-04 Jianfeng Chen CaCO3/SiO2.nH2O nanocomposite particles and SiO2.nH2O hollow-structures nanomaterials and synthesizing method
JP2005281925A (en) * 2004-03-30 2005-10-13 Nippon Paper Industries Co Ltd Neutral paper for printing newspaper
JP2021507863A (en) * 2017-12-12 2021-02-25 イメルテック ソシエテ パル アクシオン サンプリフィエ Preparation of silica-coated calcium carbonate with increased surface area and mesoporous properties

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