# US 11,078,327 B2 · Polyester copolymer and method of producing same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,078,327 B2 - Document ID: US11078327B2 - Status: Granted - Kind: B2 - Application number: 16/629,763 - Filed: 2018-08-01 - Published: 2020-07-09 - Granted: 2021-08-03 - Earliest claimed: 2017-08-17 - Assignees: Toray Industries, Inc. - Applicants: Toray Industries, Inc. - Inventors: Yoshinori Kakizawa; Koji Kadowaki; Kazuhiro Tanahashi; Hirokazu Sakaguchi; Kazuyuki Kidoba - Web page: https://patentgrep.com/patent/US11078327B2 ## CPC - C08G 63/08: Lactones or lactides - C08G 63/06: derived from hydroxycarboxylic acids - C08G 63/78: Preparation processes - C08G 63/912: {derived from hydroxycarboxylic acids} - C08L 101/16: the macromolecular compounds being biodegradable - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) ## Abstract A polyester copolymer has two types of ester bond-forming monomer residues as main structural units when the two types of ester bond-forming monomers are defined as “monomer A” and “monomer B”, respectively, the polyester copolymer satisfies (1) and (2): (1) an R value represented by equation: R value=[AB]/(2[A][B])×100 [A]: mole fraction of monomer A residues in the polyester copolymer [% by mol], [B]: mole fraction of monomer B residues in the polyester copolymer [% by mol], and [AB]: mole fraction of a structure in which the monomer A residues and the monomer B residues are adjacent to each other (A-B and B-A) in the polyester copolymer [% by mol], is 0.45 or more and 0.99 or less; and (2) a crystallization rate of at least one of the monomer A residues and the monomer B residues is less than 14%. ## Claims ### Claim 1 A polyester copolymer having two types of ester bond-forming monomer residues as main structural units, wherein, when the two types of ester bond-forming monomers are defined as “monomer A” and “monomer B”, respectively, the polyester copolymer satisfies (1) and (2): (1) an R value represented by equation: R value=[AB]/(2[A][B])×100 [A]: mole fraction of monomer A residues in the polyester copolymer [% by mol], [B]: mole fraction of monomer B residues in the polyester copolymer [% by mol], and [AB]: mole fraction of a structure in which the monomer A residues and the monomer B residues are adjacent to each other (A-B and B-A) in the polyester copolymer [% by mol], is 0.45 or more and 0.99 or less; and (2) a crystallization rate of at least one of the monomer A residues and the monomer B residues is less than 14%. ### Claim 2 (depends on 1) The polyester copolymer according to claim 1, wherein, when the monomer A and the monomer B are copolymerized in equimolar amounts, a monomer having a relatively high initial polymerization rate is defined as “monomer A” and a monomer having a relatively low initial polymerization rate is defined as “monomer B”, and the initial polymerization rates when they are copolymerized in equimolar amounts are defined as VA and VB, respectively, 1.1≤VA/VB≤40 is satisfied. ### Claim 3 (depends on 1) The polyester copolymer according to claim 1, having a structure in which two or more macromer units having a gradient structure in which the monomer A residues and the monomer B residues form a composition gradient in a skeleton are connected. ### Claim 4 (depends on 1) The polyester copolymer according to claim 1, having a weight average molecular weight of 60,000 or more. ### Claim 5 (depends on 1) The polyester copolymer according to claim 1, wherein the two types of ester bond-forming monomers are compounds selected from the group consisting of hydroxycarboxylic acid, lactone, and lactide. ### Claim 6 (depends on 5) The polyester copolymer according to claim 5, wherein the monomer A residue is a lactic acid residue, and the monomer B residue is a caprolactone residue or a valerolactone residue. ### Claim 7 (depends on 6) The polyester copolymer according to claim 6, wherein a crystallite size of a polylactic acid a crystal is 24 nm or less. ### Claim 8 (depends on 6) The polyester copolymer according to claim 6, wherein a crystallite size of polycaprolactone is 30 nm or less. ### Claim 9 (depends on 1) The polyester copolymer according to claim 1, having biodegradability or bioabsorbability. ### Claim 10 (depends on 1) The polyester copolymer according to claim 1, having a Young's modulus of 6.3 MPa or less and a maximum point stress of 5 MPa or more. ### Claim 11 A method of producing a polyester copolymer comprising: a macromer synthesis step of blending and polymerizing monomers A and monomers B, which are two types of ester bond-forming monomers so that a sum of monomer A residues and monomer B residues is 50% by mol or more of all residues, and each of the monomer A residues and the monomer B residues is 20% by mol or more of all residues at the completion of polymerization; and a multimerization step of multimerizing by connecting macromers obtained in the macromer synthesis step, or additionally adding the monomer A and the monomer B to a macromer solution obtained in the macromer synthesis step. ### Claim 12 (depends on 11) The method according to claim 11, wherein an R value of the macromer obtained in the macromer synthesis step, represented by equation: R value=[AB]/(2[A][B])×100 [A]: mole fraction of monomer A residues in the macromer [% by mol], [B]: mole fraction of monomer B residues in the macromer [% by mol], and [AB]: mole fraction of a structure in which the monomer A residues and the monomer B residues are adjacent to each other (A-B and B-A) in the macromer [% by mol], is 0.45 or more and 0.99 or less. ### Claim 13 (depends on 11) The method according to claim 11, wherein a crystallization rate of at least one of the monomer A residues and the monomer B residues of the macromer obtained in the macromer synthesis step is less than 14%. ### Claim 14 (depends on 11) The method according to claim 11, wherein the two types of ester bond-forming monomers are compounds selected from the group consisting of hydroxycarboxylic acid, lactone, and lactide. ### Claim 15 (depends on 14) The method according to claim 14, wherein the monomer A residue is a lactic acid residue, and the monomer B residue is a caprolactone residue or a valerolactone residue.