# US 11,999,627 B2 · Calcium carbonate with controlled particle morphology, method for producing the same, and crystal growth method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,999,627 B2 - Document ID: US11999627B2 - Status: Granted - Kind: B2 - Application number: 17/510,725 - Filed: 2021-10-26 - Published: 2022-05-12 - Granted: 2024-06-04 - Earliest claimed: 2020-11-06 - Assignees: Shiraishi Central Laboratories Co. Ltd. - Applicants: SHIRAISHI CENTRAL LABORATORIES Co., Ltd. - Inventors: Yuki Kezuka; Maya Yoshida - Web page: https://patentgrep.com/patent/US11999627B2 ## CPC - C01F 11/185: {After-treatment, e.g. grinding, purification, conversion of crystal morphology} - C01F 11/181: {Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions} - C08K 3/26: Carbonates; Bicarbonates - C08L 57/00: Compositions of unspecified polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds - C08L 87/00: Compositions of unspecified macromolecular compounds, obtained otherwise than by polymerisation reactions only involving unsaturated carbon-to-carbon bonds - C01P 2004/03: obtained by SEM - C01P 2004/30: extending in three dimensions - C01P 2004/62: Submicrometer sized, i.e. from 0.1-1 micrometer - C01P 2004/64: Nanometer sized, i.e. from 1-100 nanometer - C01P 2006/12: Surface area - C08K 2003/265: {Calcium, strontium or barium carbonate} - C08K 2201/005: Additives being defined by their particle size in general - C08K 2201/006: Additives being defined by their surface area - C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00}) - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS ## Abstract Provided is a calcium carbonate that comprises crystals having a particular shape and structure and has a nano-order average particle size. Provided are a method for producing a calcium carbonate that comprises crystals having a particular shape and structure and has an average particle size in a particular range and a crystal growth method. The calcium carbonate has the calcite structure, has a BET specific surface area of 2 to 50 m2/g, has a number-based average particle size of 30 nm to 1.0 μm as determined by electron microscopy, and partially comprises substantially ring-like particles. ## Claims ### Claim 1 A method for producing a calcium carbonate containing substantially ring-like particles, the method comprising the steps of: adding carbon dioxide to an aqueous calcium carbonate dispersion at room temperature and under atmospheric pressure to reduce a pH of the aqueous calcium carbonate dispersion to 9.0 or less; and then increasing the pH of the aqueous calcium carbonate dispersion to grow calcium carbonate particles. ### Claim 2 (depends on 1) The method for producing a calcium carbonate containing substantially ring-like particles according to claim 1, wherein the calcium carbonate containing substantially ring-like particles is a calcium carbonate having a calcite structure, having a BET specific surface area of 2 to 50 m2/g, and having a number-based average particle size of 30 nm to 1.0 mm as determined by electron microscopy. ### Claim 3 (depends on 2) The method for producing a calcium carbonate containing substantially ring-like particles according to claim 2, wherein the increasing the pH of the aqueous calcium carbonate dispersion is performed by methods selected from the group consisting of allowing the aqueous calcium carbonate dispersion to stand, stirring the aqueous calcium carbonate dispersion, depressurizing the aqueous calcium carbonate dispersion, heating the aqueous calcium carbonate dispersion, and adding basic substances to the aqueous calcium carbonate dispersion. ### Claim 4 (depends on 2) The method for producing a calcium carbonate containing substantially ring-like particles according to claim 2, wherein the reducing the pH of the aqueous calcium carbonate dispersion to 9.0 or less and the increasing the pH of the aqueous calcium carbonate dispersion are repeated. ### Claim 5 (depends on 2) The method for producing a calcium carbonate containing substantially ring-like particles according to claim 2, wherein a number-based average particle size of the calcium carbonate particles is 30 nm to 100 nm as determined by electron microscopy. ### Claim 6 (depends on 2) The method for producing a calcium carbonate containing substantially ring-like particles according to claim 2, wherein the size of the substantially ring-like calcium carbonate particles is 10 to 150 nm. ### Claim 7 (depends on 1) The method for producing a calcium carbonate containing substantially ring-like particles according to claim 1, wherein the increasing the pH of the aqueous calcium carbonate dispersion is performed by methods selected from the group consisting of allowing the aqueous calcium carbonate dispersion to stand, stirring the aqueous calcium carbonate dispersion, depressurizing the aqueous calcium carbonate dispersion, heating the aqueous calcium carbonate dispersion, and adding basic substances to the aqueous calcium carbonate dispersion. ### Claim 8 (depends on 7) The method for producing a calcium carbonate containing substantially ring-like particles according to claim 7, wherein the reducing the pH of the aqueous calcium carbonate dispersion to 9.0 or less and the increasing the pH of the aqueous calcium carbonate dispersion are repeated. ### Claim 9 (depends on 1) The method for producing a calcium carbonate containing substantially ring-like particles according to claim 1, wherein the reducing the pH of the aqueous calcium carbonate dispersion to 9.0 or less and the increasing the pH of the aqueous calcium carbonate dispersion are repeated. ### Claim 10 A method for growing crystals of a calcium carbonate containing substantially ring-like particles, the method comprising the steps of: adding carbon dioxide to an aqueous calcium carbonate dispersion at room temperature and under atmospheric pressure to reduce a pH of the aqueous calcium carbonate dispersion to 9.0 or less; and then increasing the pH of the aqueous calcium carbonate dispersion to grow calcium carbonate crystals. ### Claim 11 (depends on 10) The method for growing crystals of a calcium carbonate containing substantially ring-like particles according to claim 10, wherein the calcium carbonate containing substantially ring-like particles is a calcium carbonate having a calcite structure, having a BET specific surface area of 2 to 50 m2/g, and having a number-based average particle size of 30 nm to 1.0 mm as determined by electron microscopy. ### Claim 12 (depends on 11) The method for growing crystals of a calcium carbonate containing substantially ring-like particles according to claim 11, wherein the increasing the pH of the aqueous calcium carbonate dispersion is performed by methods selected from the group consisting of allowing the aqueous calcium carbonate dispersion to stand, stirring the aqueous calcium carbonate dispersion, depressurizing the aqueous calcium carbonate dispersion, heating the aqueous calcium carbonate dispersion, and adding basic substances to the aqueous calcium carbonate dispersion. ### Claim 13 (depends on 11) The method for growing crystals of a calcium carbonate containing substantially ring-like particles according to claim 11, wherein the reducing the pH of the aqueous calcium carbonate dispersion to 9.0 or less and the increasing the pH of the aqueous calcium carbonate dispersion are repeated. ### Claim 14 (depends on 11) The method for growing crystals of a calcium carbonate containing substantially ring-like particles according to claim 11, wherein a number-based average particle size of the calcium carbonate particles is 30 nm to 100 nm as determined by electron microscopy. ### Claim 15 (depends on 11) The method for growing crystals of a calcium carbonate containing substantially ring-like particles according to claim 11, wherein the size of the substantially ring-like calcium carbonate particles is 10 to 150 nm. ### Claim 16 (depends on 10) The method for growing crystals of a calcium carbonate containing substantially ring-like particles according to claim 10, wherein the increasing the pH of the aqueous calcium carbonate dispersion is performed by methods selected from the group consisting of allowing the aqueous calcium carbonate dispersion to stand, stirring the aqueous calcium carbonate dispersion, depressurizing the aqueous calcium carbonate dispersion, heating the aqueous calcium carbonate dispersion, and adding basic substances to the aqueous calcium carbonate dispersion. ### Claim 17 (depends on 16) The method for growing crystals of a calcium carbonate containing substantially ring-like particles according to claim 16, wherein the reducing the pH of the aqueous calcium carbonate dispersion to 9.0 or less and the increasing the pH of the aqueous calcium carbonate dispersion are repeated. ### Claim 18 (depends on 10) The method for growing crystals of a calcium carbonate containing substantially ring-like particles according to claim 10, wherein the reducing the pH of the aqueous calcium carbonate dispersion to 9.0 or less and the increasing the pH of the aqueous calcium carbonate dispersion are repeated.