# US 10,501,399 B2 · Lactic acid manufacturing method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,501,399 B2 - Document ID: US10501399B2 - Status: Granted - Kind: B2 - Application number: 15/129,870 - Filed: 2015-03-30 - Published: 2017-06-01 - Granted: 2019-12-10 - Earliest claimed: 2014-03-31 - Assignees: Toray Industries, Inc. - Applicants: Toray Industries, Inc. - Inventors: Kenji Kawamura; Miyuki Horiguchi; Satoshi Sakami; Katsushige Yamada - Web page: https://patentgrep.com/patent/US10501399B2 ## CPC - C07C 51/43: by change of the physical state, e.g. crystallisation - C07C 51/44: by distillation - C08G 63/06: derived from hydroxycarboxylic acids - C08G 63/08: Lactones or lactides - C08G 63/80: Solid-state polycondensation - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS ## Abstract A method of producing lactic acid includes subjecting a lactic acid-containing solution to distillation to collect lactic acid from the vapor side (Step A); subjecting the lactic acid obtained in Step A to crystallization (Step B); subjecting the lactic acid slurry obtained in Step B to solid-liquid separation into lactic acid crystals and a mother liquor (Step C); and circulating the mother liquor obtained in Step C to Step B (Step D). ## Claims ### Claim 1 A method of producing lactic acid comprising: subjecting a lactic-acid containing solution to distillation to collect lactic acid from the vapor side (Step A); subjecting the lactic acid obtained in Step A to crystallization (Step B); subjecting a lactic acid slurry obtained in (Step B) to solid-liquid separation into lactic acid crystals and a mother liquor containing a lactic acid oligomer (Step C); and circulating the mother liquor obtained in Step C to Step B (Step D), wherein a mixture of the mother liquor circulated in Step D and the lactic acid obtained in Step A is subjected to crystallization to obtain lactic acid crystals. ### Claim 2 (depends on 1) The method according to claim 1, wherein said lactic acid-containing solution is derived by microbial fermentation. ### Claim 3 (depends on 1) The method according to claim 1, wherein said crystallization in Step B is cooling crystallization, evaporative crystallization, or insulated crystallization. ### Claim 4 (depends on 1) A method of producing polylactic acid comprising: producing lactic acid by the method according to claim 1; and producing polylactic acid using said lactic acid obtained in said step as a material (Step E). ### Claim 5 (depends on 4) The method according to claim 4, wherein said Step (E) is a step of direct dehydration condensation of said lactic acid. ### Claim 6 (depends on 2) The method according to claim 2, wherein said crystallization in Step B is cooling crystallization, evaporative crystallization, or insulated crystallization. ### Claim 7 (depends on 2) A method of producing polylactic acid comprising: producing lactic acid by the method according to claim 2; and producing polylactic acid using said lactic acid obtained in said step as a material (Step E). ### Claim 8 (depends on 3) A method of producing polylactic acid comprising: producing lactic acid by the method according to claim 3; and producing polylactic acid using said lactic acid obtained in said step as a material (Step E). ### Claim 9 (depends on 7) The method according to claim 7, wherein said Step (E) is a step of direct dehydration condensation of said lactic acid. ### Claim 10 (depends on 8) The method according to claim 8, wherein said Step (E) is a step of direct dehydration condensation of said lactic acid. ### Claim 11 A method of producing lactic acid comprising: subjecting a lactic acid-containing solution to distillation to collect lactic acid from the vapor side (Step A); partially condensing vapor from the vapor side to produce liquid lactic acid and water, and condensing a remaining portion of the vapor to produce water and low boiling point components (Step A1); subjecting the lactic acid obtained in (Step A1) to crystallization (Step B); subjecting lactic acid slurry obtained in (Step B) to solid-liquid separation into lactic acid crystals and a mother liquor containing a lactic acid oligomer (Step C); and circulating the mother liquor obtained in (Step C) to (Step B) (Step D), wherein a mixture of the mother liquor circulated in Step D and the lactic acid obtained in Step A is subjected to crystallization to obtain lactic acid crystals. ### Claim 12 (depends on 11) The method according to claim 11, wherein said lactic acid-containing solution is derived by microbial fermentation. ### Claim 13 (depends on 11) The method according to claim 11, wherein said crystallization in Step B is cooling crystallization, evaporative crystallization, or insulated crystallization. ### Claim 14 (depends on 11) A method of producing polylactic acid comprising: producing lactic acid by the method according to claim 11; and producing polylactic acid using said lactic acid obtained in said step as a material (Step E). ### Claim 15 (depends on 14) The method according to claim 14, wherein said Step (E) is a step of direct dehydration condensation of said lactic acid. ### Claim 16 (depends on 12) The method according to claim 12, wherein said crystallization in Step B is cooling crystallization, evaporative crystallization, or insulated crystallization. ### Claim 17 (depends on 12) A method of producing polylactic acid comprising: producing lactic acid by the method according to claim 12; and producing polylactic acid using said lactic acid obtained in said step as a material (Step E). ### Claim 18 (depends on 13) A method of producing polylactic acid comprising: producing lactic acid by the method according to claim 13; and producing polylactic acid using said lactic acid obtained in said step as a material (Step E). ### Claim 19 (depends on 17) The method according to claim 17, wherein said Step (E) is a step of direct dehydration condensation of said lactic acid. ### Claim 20 (depends on 18) The method according to claim 18, wherein said Step (E) is a step of direct dehydration condensation of said lactic acid. ### Claim 21 A method of producing lactic acid comprising: subjecting a solution containing water and lactic acid to distillation to collect lactic acid from the vapor side (Step A), wherein the distillation comprises recovering vaporized lactic acid and a portion of the water in a first-stage condenser and recovering remaining water and low boiling components in a second-stage condenser; subjecting the lactic acid obtained in Step A to crystallization (Step B); subjecting the lactic acid slurry obtained in Step B to solid-liquid separation into lactic acid crystals and a mother liquor (Step C); and circulating the mother liquor obtained in Step C to Step B (Step D), wherein a mixture of the mother liquor circulated in Step D and the lactic acid obtained in Step A is subjected to crystallization to obtain lactic acid crystals.