# US 2018/0022867 A1 · Method for producing polyester > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0022867 A1 - Document ID: US20180022867A1 - Status: Published application - Kind: A1 - Application number: 15/543,932 - Filed: 2016-01-15 - Published: 2018-01-25 - Earliest claimed: 2015-01-19 - Assignees: Nippon Soda Co., Ltd. - Applicants: Nippon Soda Co., Ltd. - Inventors: Eiji TAKAHASHI - Web page: https://patentgrep.com/patent/US20180022867A1 ## CPC - C08G 63/823: {for the preparation of polylactones or polylactides} - C08G 63/08: Lactones or lactides - C08G 63/83: Alkali metals, alkaline earth metals, beryllium, magnesium, copper, silver, gold, zinc, cadmium, mercury, manganese, or compounds thereof {(C08G63/823 takes precedence)} - C08G 63/84: Boron, aluminium, gallium, indium, thallium, rare-earth metals, or compounds thereof {(C08G63/823 takes precedence)} - C08G 63/87: Non-metals or inter-compounds thereof (boron C08G63/84) - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS ## Abstract A cyclic ester such as lactides and the like is mixed, in an organic solvent, with an alkyl aluminum compound such as trimethyl aluminum, triethyl aluminum and the like, and then, to the resulting mixture, at least one selected from the group consisting of an organic lithium ring-opening polymerization catalyst, an organic sodium ring-opening polymerization catalyst, an organic potassium ring-opening polymerization catalyst, an organic zinc ring-opening polymerization catalyst, an organic magnesium ring-opening polymerization catalyst, an organic tin ring-opening polymerization catalyst, an organic calcium ring-opening polymerization catalyst, an organic titanium ring-opening polymerization catalyst, and an amine ring-opening polymerization catalyst to allow ring-opening polymerization of the cyclic ester, thereby a polyester is obtained. ## Claims ### Claim 1 A method for producing polyester, the method comprising: mixing, in an organic solvent, a cyclic ester with an alkyl aluminum compound represented by a formula [I]: Rn Al X3-n wherein, in the formula [I], n represents an integer from 1 to 3, R each independently represents a linear or branched C1-20 alkyl group, and X each independently represents a halogen atom or a hydrogen atom; and then mixing the resulting mixture with at least one ring-opening polymerization catalyst selected from the group consisting of an organic lithium ring-opening polymerization catalyst, an organic sodium ring-opening polymerization catalyst, an organic potassium ring-opening polymerization catalyst, an organic zinc ring-opening polymerization catalyst, an organic magnesium ring-opening polymerization catalyst, an organic tin ring-opening polymerization catalyst, an organic calcium ring-opening polymerization catalyst, an organic titanium ring-opening polymerization catalyst, and an amine ring-opening polymerization catalyst to allow ring-opening polymerization of the cyclic ester. ### Claim 2 (depends on 1) The method for producing polyester according to claim 1, wherein a temperature in the mixing the cyclic ester with the alkyl aluminum compound is not more than 70° C. ### Claim 3 (depends on 1) The method for producing polyester according to claim 1, wherein the alkyl aluminum compound is at least one selected from the group consisting of trimethyl aluminum, triethyl aluminum, tri-isobutyl aluminum, tri-n-hexyl aluminum, tri-n-butyl aluminum, tri-n-octyl aluminum, diethyl aluminum chloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride, and diisobutyl aluminum hydride. ### Claim 4 (depends on 1) The method for producing polyester according to claim 1, wherein the cyclic ester is lactides. ### Claim 5 (depends on 1) The method for producing polyester according to claim 1, wherein the cyclic ester is a compound having 1,4-dioxane-2,5-dione structure. ### Claim 6 (depends on 1) The method for producing polyester according to claim 1, wherein the cyclic ester is represented by a formula [III]: wherein, in the formula [III], R1 and R2 each independently represent a hydrogen atom, a linear or branched C1-20 alkyl group, a linear or branched C1-20 haloalkyl group, a linear or branched C2-20 alkenyl group, a linear or branched C2-20 alkynyl group, a C4-6 cycloalkyl group, a linear or branched C1-20 alkyl carbonyl group, a linear or branched C1-20 alkoxy carbonyl group, a linear or branched C1-20 haloalkyl carbonyl group, a linear or branched C2-20 alkenyl carbonyl group, a linear or branched C2-20 alkynyl carbonyl group, a C4-6 cycloalkyl carbonyl group, 2-(methylthio)ethyl group, 2-(methylsulfinyl)ethyl group, 2-(methylsulfonyl)ethyl group, benzyl group, or phenyl group. ### Claim 7 (depends on 1) The method for producing polyester according to claim 1, wherein the ring-opening polymerization catalyst is at least one selected from the group consisting of an organic lithium ring-opening polymerization catalyst, an organic sodium ring-opening polymerization catalyst, an organic potassium ring-opening polymerization catalyst, dialkyl zinc, bis(2,2,6,6-tetramethylpiperidinyl) zinc, alkyl zinc halide, substituted alkyl zinc halide, cycloalkyl zinc halide, aryl zinc halide, 2-norbornyl zinc bromide, dialkyl magnesium, organic magnesium halide, tin alkoxide, and an amine ring-opening polymerization catalyst. ### Claim 8 (depends on 1) The method for producing polyester according to claim 1, wherein the ring-opening polymerization catalyst is at least one selected from the group consisting of dialkyl zinc, dialkyl magnesium, and an amine ring-opening polymerization catalyst. ### Claim 9 (depends on 1) The method for producing polyester according to claim 1, wherein the amount of the alkyl aluminum compound is 0.5 mol to 5 mol based on 1 mol of the cyclic ester. ### Claim 10 (depends on 1) The method for producing polyester according to claim 1, wherein the amount of the ring-opening polymerization catalyst is 0.01 mol to 10 mol based on 1 mol of the cyclic ester.