Polymer composition and molded article

Abstract

A polymer composition comprising a polyester copolymer and a biodegradable polymer, wherein the polyester copolymer includes two types of ester bond-forming monomer residues as main structural units, the polyester copolymer satisfies (1)-(3) when the two types of ester bond-forming monomers are defined as "monomer A" and "monomer B", the biodegradable polymer has a melting point not less than 100°C, and the contained amount of the biodegradable polymer is not less than 0.1 wt% but less than 30 wt% in 100 wt% of the total of the polyester copolymer and the biodegradable polymer. Provided is a polymer composition that has a low Young's modulus and a high tensile strength.　(1) The R value being 0.45-0.99. R=[AB] / (2[A][B])×100 [A]: Molar fraction (%) of monomer A residue in polyester copolymer. [B]: Molar fraction (%) of monomer B residue in polyester copolymer. [AB]: Molar fraction (%) of structures (A-B and B-A) in which monomer A residue and monomer B residue are located adjacently in polyester copolymer. (2) The crystallization rate of monomer A residue and monomer B residue being less than 14%.　(3) The melting point being less than 100°C or being indistinctive.

Description

[Technical Field]

[0001] The present invention relates to a polymer composition containing a polyester copolymer and a biodegradable polymer. [Background technology]

[0002] Polyesters produced from ester bond-forming monomers, such as polylactic acid, polyglycolic acid, polycaprolactone, and copolymers thereof, have attracted attention as biodegradable or bioabsorbable polymers and are used in a wide range of applications, including medical materials such as sutures, sustained-release materials for medicines, agricultural chemicals, fertilizers, etc. Furthermore, they are expected to be used as general-purpose biodegradable plastics for packaging materials such as containers and films.

[0003] However, biodegradable and bioabsorbable polyesters produced from ester bond-forming monomers are generally brittle, and therefore attempts have been made to develop various copolymers with improved mechanical properties to obtain biodegradable polymers with sufficient strength and moldability for practical use.

[0004] For example, a polyester copolymer has been proposed as a biodegradable and bioabsorbable polymer with a low Young's modulus and high tensile strength, which is composed mainly of residues of two types of ester bond-forming monomers ("monomer A" and "monomer B"), in which the R value represented by the following formula is 0.45 or more and 0.99 or less, and in which the crystallinity of at least one of the monomer A residues or monomer B residues is less than 14% (see, for example, Patent Document 1). R = [AB] / (2[A][B]) × 100 [A]: Molar fraction (%) of monomer A residues in the polyester copolymer [B]: Molar fraction (%) of monomer B residues in the polyester copolymer [AB]: The mole fraction (%) of the structure in which monomer A residue and monomer B residue are adjacent to each other in the polyester copolymer.

[0005] Attempts have also been made to improve mechanical properties by blending multiple biodegradable polymers. For example, as compositions with improved strength, flexibility, elongation, toughness, etc., proposed are polymer blends containing a hard synthetic biodegradable polymer and a soft synthetic biodegradable polymer, where the polymer blend has higher strength and / or elongation than the hard or soft biodegradable polymer itself (see, for example, Patent Document 2), resin compositions containing polylactic acid, L-lactide / ε-caprolactone copolymer, and filler (see, for example, Patent Document 3), blends of poly(D-lactic acid) and L-lactide / ε-caprolactone copolymer, or blends of poly(L-lactic acid) and D-lactide / ε-caprolactone copolymer (see, for example, Patent Document 4), etc. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2019 / 35357 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-255349 [Patent Document 3] Japanese Patent Application Publication No. 2017-179234 [Patent Document 4] Special Publication No. 2020-529483 Summary of the Invention [Problem to be solved by the invention]

[0007] Generally, polylactic acid and polyglycolic acid are known to have high crystallinity, a high Young's modulus, and hardness. However, these polymers lack flexibility and lack the bioconformity required for medical materials. Furthermore, due to their hardness, they have been reported to damage surrounding tissues and cause extrusion accidents when embedded in the body.

[0008] Therefore, copolymerization of these polymers with polycaprolactone has been studied to impart flexibility. The multi-gradient polymer described in Patent Document 1 has a low Young's modulus, improving flexibility, which was previously a problem, and is suitable for use as a filling material or coating material. However, for applications requiring the ability to conform to large deformations, such as implantation into joints, the tensile strength is insufficient, and further improvement is necessary.

[0009] Furthermore, the resin compositions described in Patent Documents 2 to 4 have a high Young's modulus and are poor in bioconformity and moldability, so there is a demand for materials with a low Young's modulus.

[0010] In view of the above problems, an object of the present invention is to provide a polymer composition having a low Young's modulus and a high tensile strength. [Means for solving the problem]

[0011] The present invention for solving the above problems is as follows.

[0012] A polymer composition comprising a polyester copolymer and a biodegradable polymer, The polyester copolymer has two types of ester bond-forming monomer residues as main structural units, The polyester copolymer satisfies the following (1) to (3), where the two types of ester bond-forming monomers are designated as "monomer A" and "monomer B," respectively: The biodegradable polymer has a melting point of 100°C or higher, A polymer composition comprising 0.1% by weight or more and less than 30% by weight of the biodegradable polymer in a total of 100% by weight of the polyester copolymer and the biodegradable polymer: (1) The R value is 0.45 or more and 0.99 or less; R = [AB] / (2[A][B]) × 100 [A]: Molar fraction (%) of monomer A residues in the polyester copolymer [B]: Molar fraction (%) of monomer B residues in the polyester copolymer [AB]: mole fraction (%) of structures in which a monomer A residue and a monomer B residue are adjacent to each other (AB and BA) in the polyester copolymer; (2) the crystallinity of the monomer A residue and the crystallinity of the monomer B residue are less than 14%; (3) The melting point is less than 100°C or does not have a clear melting point. [Effects of the Invention]

[0013] According to the present invention, it is possible to obtain a polymer composition that has a low Young's modulus, biodegradability or bioabsorbability, and excellent tensile strength, and is suitable for medical applications and elastomer applications. DETAILED DESCRIPTION OF THE INVENTION

[0014] The polymer composition of the present invention contains a polyester copolymer and a biodegradable polymer. The polyester copolymer is a copolymer whose main structural units are two types of ester bond-forming monomer residues. In this specification, the two types of ester bond-forming monomers may be referred to as "monomer A" and "monomer B," respectively. Furthermore, in the copolymer formed from "monomer A" and "monomer B," the monomer residues derived from "monomer A" and "monomer B" may be referred to as "monomer A residue" and "monomer B residue," respectively.

[0015] The term "ester bond-forming monomer" refers to a monomer that, when polymerized, produces a polymer in which monomer units are linked by ester bonds, i.e., a polyester.

[0016] As the ester bond-forming monomer, a hydroxycarboxylic acid is preferably used. Also preferably used are lactones, which are cyclic compounds formed by intramolecular dehydration condensation of the hydroxy group and the carboxyl group of a hydroxycarboxylic acid, and lactides, which are cyclic compounds formed by dehydration condensation of the hydroxy group and the carboxyl group of two molecules of hydroxycarboxylic acid.

[0017] It is particularly preferable to use an aliphatic hydroxycarboxylic acid as the hydroxycarboxylic acid. Examples of aliphatic hydroxycarboxylic acids include lactic acid, glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxynonanoic acid, hydroxydecanoic acid, hydroxyundecanoic acid, hydroxydodecanoic acid, and (2-hydroxyethoxy)acetic acid. In particular, compounds selected from lactic acid, glycolic acid, hydroxyvaleric acid, and hydroxycaproic acid are preferred.

[0018] Although L-lactic acid, D-lactic acid, and a mixture thereof can be used as the lactic acid, it is preferable to use L-lactic acid in terms of the physical properties and biocompatibility of the resulting polymer. When a mixture is used as a monomer, the L-lactic acid content is preferably 85% or more, and more preferably 95% or more.

[0019] Examples of lactones that can be used include butyrolactone, valerolactone, caprolactone, dioxepanone, ethylene oxalate, p-dioxanone, trimethylene carbonate, β-propiolactone, and pivalolactone. In particular, butyrolactone, valerolactone, caprolactone, p-dioxanone, and trimethylene carbonate are preferred, and valerolactone or caprolactone is more preferred.

[0020] As the lactide, dilactide obtained by dehydration condensation of two molecules of lactic acid, glycolide obtained by dehydration condensation of two molecules of glycolic acid, tetramethyl glycolide, etc. can be used, with dilactide or glycolide being particularly preferred.

[0021] As the ester bond-forming monomer, derivatives of the above-exemplified monomers can also be used.

[0022] Among these, in the present invention, it is more preferred that Monomer A and Monomer B are each formed from a compound selected from the group consisting of lactic acid, glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxynonanoic acid, hydroxydecanoic acid, hydroxyundecanoic acid, hydroxydodecanoic acid, (2-hydroxyethoxy)acetic acid, butyrolactone, valerolactone, caprolactone, dioxepanone, ethylene oxalate, p-dioxanone, trimethylene carbonate, β-propiolactone, pivalolactone, dilactide, glycolide, and tetramethylglycolide. Monomer A is more preferably a compound selected from the group consisting of lactic acid, glycolic acid, dilactide, and glycolide, and is particularly preferably lactic acid or glycolic acid. Monomer B is more preferably a compound selected from the group consisting of hydroxyvaleric acid, hydroxycaproic acid, valerolactone, and caprolactone, and is particularly preferably caprolactone or δ-valerolactone.

[0023] In this specification, of the two types of ester-bonding monomers, the one having high crystallinity in the homopolymer composed only of the monomer residues is referred to as Monomer A, and the one having low crystallinity is referred to as Monomer B.

[0024] The crystallinity of homopolymers is measured by the DSC method using a differential scanning calorimeter, as described below. For example, the heat of fusion per unit weight of a homopolymer consisting only of lactic acid residues is 135 J / g, and the heat of fusion per unit weight of a homopolymer consisting only of caprolactone residues is 51 J / g. In other words, if a polyester copolymer has lactic acid residues and caprolactone residues as its main structural units, lactic acid is monomer A and caprolactone is monomer B.

[0025] In the present invention, the crystallinity of the monomer A residue and the crystallinity of the monomer B residue in the polyester copolymer are both less than 14%. If the crystallinity is less than 14%, an increase in Young's modulus is suppressed, and a polymer composition suitable for medical materials and elastomer applications can be obtained. The crystallinity of the monomer A residue and the monomer B residue is preferably 10% or less, and more preferably 5% or less.

[0026] The crystallinity ratio of a monomer residue referred to here is the ratio of the heat of fusion per unit weight of a monomer residue in a polyester copolymer to the product of the heat of fusion per unit weight of a homopolymer consisting of only that monomer residue and the weight fraction of that monomer residue in the polyester copolymer.

[0027] That is, the crystallinity ratio of monomer A residue is the ratio of the heat of fusion per unit weight of monomer A residue in a polyester copolymer to the product of the heat of fusion per unit weight of a homopolymer consisting of only monomer A and the weight fraction of monomer A residue in the polyester copolymer. The crystallinity ratios of monomer A residue and monomer B residue indicate the proportion of monomer A residue or monomer B residue contained in a polyester copolymer that form a crystalline structure, respectively.

[0028] When the monomer A residue is a lactic acid residue and the monomer B residue is a caprolactone residue, the crystallinity of the lactic acid residue and the caprolactone residue is preferably less than 14%, more preferably 10% or less.

[0029] The crystallinity ratio is specifically determined by the following method.

[0030] The polyester copolymer was dissolved in chloroform to a concentration of 5 wt%, and the solution was transferred to a Teflon petri dish and dried overnight at room temperature under atmospheric pressure. This was then dried under reduced pressure to obtain a polyester copolymer film. The resulting polyester copolymer film was placed on an alumina PAN and measured by the DSC method using a differential scanning calorimeter under the following conditions. The heat of fusion was calculated from the measurement results of the melting peak observed between the following temperature conditions (D) and (E).

[0031] Device name: EXSTAR 6000 (Seiko Instruments Inc.) Temperature conditions: (A) 25℃ → (B) 250℃ (10℃ / min) → (C) 250℃ (5min) → (D) -70℃ (10℃ / min) → (E) 250℃ (10℃ / min) → (F) 250℃ (5min) → (G) 25℃ (100℃ / min) Standard material: Alumina Here, the above temperature conditions mean that the temperature was increased from 25°C to 250°C at a rate of 10°C / min (1st run), held at 250°C for 5 minutes, then decreased to -70°C at a rate of 10°C / min, and then increased again to 250°C at a rate of 10°C / min (2nd run), held at 250°C for 5 minutes, and then decreased to 25°C at a rate of 100°C / min. In other words, the melting peak observed between temperature conditions (D) and (E) means the melting peak observed during the temperature increase in the 2nd run (the same applies hereinafter).

[0032] Next, a homopolymer consisting only of residues of monomer A, which forms a polyester copolymer, and a homopolymer consisting only of residues of monomer B are prepared. The crystallinity of each homopolymer can be measured using a differential scanning calorimeter (DSC) in the same manner as for the polyester copolymer described above.

[0033] The crystallization rate is calculated using the following formula. Crystallinity rate of monomer A residue = (heat of fusion per unit weight of monomer A residue of polyester copolymer) / {(heat of fusion per unit weight of homopolymer consisting only of monomer A residue) × (weight fraction of monomer A residue in polyester copolymer)} × 100 (%) Crystallinity ratio of monomer B residue = (heat of fusion per unit weight of monomer B residue of polyester copolymer) / {(heat of fusion per unit weight of homopolymer consisting only of monomer B residue) × (weight fraction of monomer B residue in polyester copolymer)} × 100 (%) In this specification, the term "monomer residue" generally refers to a repeating unit of a chemical structure derived from a monomer in the chemical structure of a copolymer obtained by polymerizing two or more monomers including the monomer. For example, a copolymer of lactic acid (CH3CH(OH)COOH) and caprolactone (ε-caprolactone: formula below)

[0034] [ka]

[0035] When a copolymer of lactic acid and caprolactone is obtained by polymerizing

[0036] [ka]

[0037] The unit represented by the above formula is a lactic acid monomer residue, and the unit represented by the following formula is a caprolactone monomer residue.

[0038] [ka]

[0039] However, as an exception, when a dimer such as lactide is used as a monomer, the term "monomer residue" refers to one of the two repeating structures derived from the dimer. For example, dilactide (L-(-)-lactide: formula below)

[0040] [ka]

[0041] When caprolactone is polymerized with dilactide, the copolymer has a structure represented by the above formula (R1) as a monomer residue derived from dilactide, i.e., a structure in which two lactic acid residues are repeated. In this case, one of the lactic acid residues is considered to be the "monomer residue." In other words, it is considered that two lactic acid residues, which are "monomer residues," are formed from the dilactide monomer.

[0042] The phrase "two types of monomer residues are the main structural units" means that, when the sum of all monomer residues contained in the entire polymer, including other monomer residues, is taken as 100 mol %, the sum of the numbers of the two types of monomer residues is 50 mol % or more, and when the sum of all monomer residues contained in the entire polymer is taken as 100 mol %, each of the two types of monomer residues accounts for 20 mol % or more. For example, the phrase "monomer A residues and monomer B residues are the main structural units" means that, when the sum of all monomer residues contained in the entire polymer is taken as 100 mol %, the sum of the numbers of monomer A residues and monomer B residues is 50 mol % or more, and the monomer A residues are 20 mol % or more, and the monomer B residues are 20 mol % or more. Here, the molar fractions of the monomer A residues, monomer B residues, and other residues can be determined by nuclear magnetic resonance (NMR) measurement from the area values ​​of the signals derived from each residue. For example, when the monomer A residues are lactic acid residues and the monomer B residues are caprolactone residues, they can be measured by the method described in Measurement Example 1 below.

[0043] When the sum of all monomer residues contained in the entire polymer, including other monomer residues, is taken as 100 mol %, the sum of monomer A residues and monomer B residues is preferably 75 mol % or more, more preferably 90 mol % or more. Furthermore, when the sum of all monomer residues contained in the entire polymer is taken as 100 mol %, the sum of monomer A residues and monomer B residues is preferably 30 mol % or more, more preferably 40 mol % or more, respectively. A polymer in which the sum of monomer A residues and monomer B residues is 100 mol % of the entire polymer, i.e., composed only of monomer A and monomer B, is an especially preferred embodiment.

[0044] As long as the effects of the present invention are not impaired, other monomers copolymerizable with the two ester bond-forming monomers constituting the main structural units can also be copolymerized. As such monomers, any of the above-mentioned ester bond-forming monomers other than Monomer A and Monomer B can be used.

[0045] Copolymerization of a monomer that functions as a linker is also a preferred embodiment. Examples of the monomer that functions as a linker include hydroxycarboxylic acids other than the two ester bond-forming monomers that constitute the main structural units, dialcohols, dicarboxylic acids, amino acids, diamines, diisocyanates, and diepoxides.

[0046] In this specification, the term "polyester copolymer" also includes copolymers that contain monomers other than ester bond-forming monomers as constituent units, and thereby contain constituent units that are linked in part by bonds other than ester bonds.

[0047] The polyester copolymer is preferably biodegradable or bioabsorbable. Those skilled in the art can synthesize copolymers that exhibit appropriate biodegradability or bioabsorbability depending on the application by appropriately combining the above-exemplified monomers and adjusting the ratio of the monomers within the range specified in the present invention.

[0048] The polyester copolymer has a melting point of less than 100°C or no clear melting point. The melting point can be measured using a melting point measuring device or DSC, and is preferably measured using DSC. When measured using DSC, the melting point is specifically determined by the following method.

[0049] The polyester copolymer is dissolved in chloroform to a concentration of 5% by weight, and the solution is transferred to a Teflon petri dish and dried overnight at room temperature and atmospheric pressure. This is then dried under reduced pressure to obtain a polyester copolymer film. The resulting polyester copolymer film is placed on an alumina PAN and measured using a differential scanning calorimeter under the following conditions using the DSC method. The melting point is determined to be the temperature of the melting peak observed between temperature conditions (D) and (E). If no clear melting peak is observed within this range, the sample is deemed to have no clear melting point.

[0050] Device name: EXSTAR 6000 (Seiko Instruments Inc.) Temperature conditions: (A) 25℃ → (B) 250℃ (10℃ / min) → (C) 250℃ (5min) → (D) -70℃ (10℃ / min) → (E) 250℃ (10℃ / min) → (F) 250℃ (5min) → (G) 25℃ (100℃ / min) Standard material: Alumina In the polyester copolymer, when one monomer is present in excess, the properties of the polyester copolymer approach those of a homopolymer. Therefore, the molar ratio of the monomer A residue relative to the total number of moles of the monomer A residue and the monomer B residue (100%) is preferably 20 to 80%, more preferably 30 to 70%, and even more preferably 40 to 60%.

[0051] The polyester copolymer has an R value of 0.45 or more and 0.99 or less, represented by the following formula, where the two types of ester bond-forming monomers are "monomer A" and "monomer B", respectively.

[0052] R = [AB] / (2[A][B]) × 100 [A]: Molar fraction (%) of monomer A residues in the polyester copolymer [B]: Molar fraction (%) of monomer B residues in the polyester copolymer [AB]: mole fraction (%) of structures (AB and BA) in which monomer A residue and monomer B residue are adjacent to each other in the polyester copolymer The R value is used as an index showing the randomness of the arrangement of monomer residues in a copolymer whose main structural units are two types of ester bond-forming monomer residues, namely, monomer A residue and monomer B residue. For example, the R value of a random copolymer in which the monomer arrangement is completely random is 1.

[0053] The R value can be determined by quantifying the ratio of AA, BB, AB, and BA combinations of adjacent two monomer residues (hereinafter sometimes referred to as dyads) using nuclear magnetic resonance (NMR) measurements. Specifically, this is measured using the method described in Measurement Example 1 below. For example, if a polyester copolymer consists only of monomer A and monomer B, [AB] refers to the ratio of the total number of AB dyads and BA dyads to the total number of all dyads (AA, BB, AB, BA) in the polyester copolymer. For example, if a polyester copolymer consists of three components, monomer A, monomer B, and monomer C, [AB] refers to the ratio of the total number of AB dyads and BA dyads to the total number of all dyads (AA, BB, AB, BA, AC, CA, BC, CB, CC) in the polyester copolymer. The same applies when the polyester copolymer consists of four or more monomers.

[0054] If the R value is less than 0.45, the polyester copolymer will have high crystallinity, and the resulting molded article will be hard and the Young's modulus may increase. On the other hand, if the R value exceeds 0.99, the resulting molded article will be too soft and sticky, which may reduce handleability. From the same viewpoint, the R value of the polyester copolymer is preferably 0.45 to 0.85 or 0.50 to 0.99, more preferably 0.45 to 0.80 or 0.50 to 0.85, and even more preferably 0.50 to 0.80.

[0055] The weight average molecular weight of the polyester copolymer is preferably 60,000 or more, more preferably 100,000 or more, and even more preferably 150,000 or more, in order to control the tensile strength within a suitable range. Although there is no particular upper limit, in order to control the molding processability within a suitable range, the weight average molecular weight is preferably 1,000,000 or less, more preferably 800,000 or less, and even more preferably 500,000 or less. The weight average molecular weight of the polyester copolymer can be measured, for example, by the method described in Measurement Example 2. For example, the polyester copolymer can be prepared by a macromer synthesis step of blending and polymerizing two ester bond-forming monomers, namely, Monomer A and Monomer B, in such amounts that, at the completion of polymerization, the sum of Monomer A residues and Monomer B residues in the resulting polyester copolymer accounts for 50 mol % or more of all residues, and Monomer A residues and Monomer B residues each account for 20 mol % or more of all residues; a multiplication step of linking the macromers obtained in the macromer synthesis step to each other, or of adding the monomer A and the monomer B to the macromer solution obtained in the macromer synthesis step and further polymerizing them to form a multimer; The polyester copolymer can be produced by a method for producing the polyester copolymer having the formula:

[0056] [Macromer synthesis process] In the macromer synthesis step, monomer A and monomer B are polymerized by mixing them in amounts such that, theoretically, at the completion of polymerization, the sum of monomer A residues and monomer B residues in the resulting polyester copolymer will be 50 mol % or more of all residues, and monomer A residues and monomer B residues will each be 20 mol % or more of all residues. This produces a polyester copolymer whose main structural units are monomer A residues and monomer B residues, but because this production method also includes a multi-component step described below, the polyester copolymer obtained by this step will be referred to as a "macromer" in this specification.

[0057] As the ester bond-forming monomer, those mentioned above can be used, and preferred combinations etc. also follow the above description.

[0058] The randomness of the distribution of monomer residues constituting a polyester copolymer, whose main structural units are two types of ester bond-forming monomer residues, varies depending on the reactivity of each monomer during polymerization. That is, if one of the two types of monomers is bound to the other with equal probability during polymerization, a copolymer with completely randomly distributed monomer residues is obtained. However, if there is a tendency for one monomer to be bound to the other, a gradient copolymer with a biased distribution of monomer residues is obtained. The resulting gradient copolymer has a continuously changing monomer residue composition along the molecular chain from the polymerization initiation end to the polymerization termination end.

[0059] Here, assuming that monomer A has a higher initial polymerization rate than monomer B, when monomer A and monomer B are copolymerized in the macromer synthesis step, monomer A is likely to bond after monomer A. Therefore, the synthesized macromer forms a gradient structure, which forms a compositional gradient in which the proportion of monomer A units gradually decreases from the polymerization initiation end to the polymerization termination end. That is, the macromer obtained in this step has a gradient structure in which monomer A residues and monomer B residues form a compositional gradient in the skeleton due to the difference in the initial polymerization rates of monomer A and monomer B. In other words, by using monomer A and monomer B with different initial polymerization rates in this step, it is possible to obtain a macromer with a gradient structure that forms a compositional gradient in the skeleton. Such a macromer may be referred to herein as a "gradient macromer."

[0060] In order to realize such a gradient structure in the macromer synthesis process, it is desirable to synthesize the macromer by a polymerization reaction that occurs in one direction from the initiation terminal. Preferred examples of such a synthesis reaction include ring-opening polymerization or living polymerization.

[0061] The macromer obtained in this step has an R value similar to that of the polyester copolymer, i.e., a macromer represented by the following formula, in order to facilitate the final production of a polyester copolymer satisfying the above-mentioned R value. R = [AB] / (2[A][B]) × 100 [A]: Molar fraction (%) of monomer A residues in the macromer [B]: Molar fraction (%) of monomer B residues in the macromer [AB]: Molar fraction (%) of structures in which monomer A residue and monomer B residue are adjacent (AB and BA) in the macromer The R value represented by the formula is preferably 0.45 or more and 0.99 or less, and more preferably 0.50 or more and 0.80 or less.

[0062] The weight-average molecular weight of the macromer synthesized in the macromer synthesis step is preferably 10,000 or more, more preferably 20,000 or more. In order to suppress crystallinity and maintain flexibility, the weight-average molecular weight of the macromer is preferably 150,000 or less, more preferably 100,000 or less.

[0063] [Mulching process] In the multi-polymerization step, multiple macromers obtained in the macromer synthesis step are linked together, or monomer A and monomer B are added to the macromer solution obtained in the macromer synthesis step and further polymerized to form multiple macromers. In this step, macromers obtained in one macromer synthesis step may be linked together, or multiple macromers obtained in two or more macromer synthesis steps may be linked. Note that "multi-polymerization" refers to the formation of a polyester copolymer having a structure in which multiple macromer units are linked together, each having a gradient structure in which monomer A residues and monomer B residues have a composition gradient in the backbone.

[0064] The number of multi-linked macromer units should be 2 or more, but since a larger number of linked units has the effect of improving tensile strength due to entanglement of molecular chains, it is preferably 3 or more, more preferably 4 or more, and even more preferably 6 or more. On the other hand, if the molecular weight of the polyester copolymer increases excessively, there is a concern that the viscosity will increase and adversely affect moldability, so the number of macromer units is preferably 80 or less, more preferably 40 or less, and even more preferably 20 or less.

[0065] The number of linked macromer units can be adjusted by the catalyst used in the multi-polymerization process and the reaction time. When linking macromers to each other to form multi-polymers, the number of macromer units can be determined by dividing the weight-average molecular weight of the final polyester copolymer by the weight-average molecular weight of the macromer.

[0066] The polyester copolymer may be a linear polymer in which macromer units are linearly linked, or a branched polymer in which macromer units are branched and linked.

[0067] A linear polyester copolymer can be synthesized, for example, by bonding one molecule of a gradient macromer to each end of a gradient macromer via the ends.

[0068] When the gradient macromer has a hydroxyl group and a carboxyl group at both ends, the ends can be condensed with a condensing agent to obtain a multi-polyester copolymer. Examples of the condensing agent include 4,4-dimethylaminopyridinium p-toluenesulfonate, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, N,N'-carbonyldiimidazole, 1,1'-carbonyldi(1,2,4-triazole), and 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholino. Trifluoromethanesulfonate (4,6-dimethoxy-1,3,5-triazin-2-yl)-(2-octoxy-2-oxoethyl)dimethylammonium, 1H-benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate, 1H-benzotriazol-1-yloxytripyrrolidinophosphonium hexafluorophosphate, (7-azabenzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate, Lorotripyrrolidinophosphonium hexafluorophosphate, Bromotris(dimethylamino)phosphonium hexafluorophosphate, 3-(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one, O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, O-(7-azabenzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, O-(N-succinimidyl)-N,N, N',N'-Tetramethyluronium tetrafluoroborate, O-(N-succinimidyl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, O-(3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate, S-(1-oxido-2-pyridyl)-N,N,N',N'-tetramethylthiuronium tetrafluoroborate, O-[2-oxo-1(2H)-pyridyl]-N,N,N',Examples of usable compounds include N'-tetramethyluronium tetrafluoroborate, {{[(1-cyano-2-ethoxy-2-oxoethylidene)amino]oxy}-4-morpholinomethylene}dimethylammonium hexafluorophosphate, 2-chloro-1,3-dimethylimidazolinium hexafluorophosphate, 1-(chloro-1-pyrrolidinylmethylene)pyrrolidinium hexafluorophosphate, 2-fluoro-1,3-dimethylimidazolinium hexafluorophosphate, and fluoro-N,N,N',N'-tetramethylformamidinium hexafluorophosphate.

[0069] Furthermore, if the polymerization reaction is living, i.e., if the polymerization reaction can be initiated continuously from the end of the polymer, multimerization can be achieved by repeatedly adding additional monomers A and B to the gradient macromer solution after the polymerization reaction has been completed and polymerizing them further.

[0070] Alternatively, gradient macromers may be multi-linked via a linker, provided that the mechanical properties of the polymer are not affected. In particular, the use of a linker having multiple carboxyl groups and / or multiple hydroxyl groups, such as 2,2-bis(hydroxymethyl)propionic acid, allows the synthesis of branched polyester copolymers at the linker.

[0071] The polyester copolymer obtained by the above-described production method is a copolymer having a structure in which two or more macromer units, each having a composition gradient in the backbone, are linked together from a monomer A residue and a monomer B residue. This is a preferred embodiment of the polyester copolymer of the present invention. In this specification, for convenience, such a structure may be referred to as a "multigradient" structure, and a copolymer having a multigradient structure may be referred to as a "multigradient copolymer." In other words, the polyester copolymer is preferably a multigradient copolymer.

[0072] The polyester copolymer preferably has a structure in which two or more macromer units are linked, and more preferably has a structure in which three or more macromer units are linked, and the upper limit of the number of linked macromer units is preferably 80 or less, more preferably 40 or less, and even more preferably 20 or less.

[0073] As described above, a particularly preferred embodiment of the present invention is a polyester copolymer in which the residue of monomer A is a lactic acid residue and the residue of monomer B is a caprolactone residue. Such a polyester copolymer is preferably produced by the following production method.

[0074] First, in the macromer synthesis process, dilactide and ε-caprolactone are polymerized in the presence of a catalyst. Dilactide and ε-caprolactone are preferably purified to remove impurities before use. Purification of dilactide can be achieved, for example, by recrystallization using sodium-dried toluene as a solvent. ε-caprolactone can be purified, for example, by vacuum distillation from CaH2 under an N2 atmosphere.

[0075] As a catalyst for the synthesis of a macromer having lactic acid residues and caprolactone residues, polyester polymerization catalysts such as conventional germanium-based catalysts, titanium-based catalysts, antimony-based catalysts, and tin-based catalysts can be used. Specific examples of such polyester polymerization catalysts include tin octoate, antimony trifluoride, zinc powder, dibutyltin oxide, and tin oxalate. The method for adding the catalyst to the reaction system is not particularly limited, but it is preferably added in a state dispersed in the raw materials when they are charged, or in a state dispersed at the start of pressure reduction. The amount of catalyst used is 0.01 to 3 parts by weight, more preferably 0.05 to 1.5 parts by weight, calculated as metal atoms, based on 100 parts by weight of the total amount of monomers used.

[0076] A macromer having lactic acid residues and caprolactone residues can be obtained by placing dilactide, caprolactone, and a catalyst in a reaction vessel equipped with a stirrer and reacting them at 120 to 250°C under a nitrogen stream. When using water as a co-initiator, it is preferable to carry out a co-catalyst reaction at around 90°C prior to the polymerization reaction. The reaction time is 2 hours or more, preferably 4 hours or more, and even longer, such as 8 hours or more, is preferable to increase the degree of polymerization. However, since a reaction that is too long can cause problems with polymer coloration, a reaction time of 3 to 30 hours is preferred.

[0077] Next, in the multi-polymerization step, the terminals of the gradient macromers having lactic acid residues and caprolactone residues are linked together by a condensation reaction to form multi-polymers. The reaction temperature for the condensation reaction is preferably 10 to 100°C, more preferably 20 to 50°C. The reaction time is preferably one day or more, more preferably two days or more. However, if the reaction is carried out for too long, the polymer may become discolored, so the reaction time is preferably two to four days.

[0078] The polyester copolymer has a structure in which two or more macromer units are linked together, and the rate of the faster initial polymerization rate of the monomer A and the monomer B is V X , the slower initial polymerization rate is V Y In this case, the macromer unit satisfies the condition 1.1≦V X / V Y It is preferable that the main structural units are monomer A residues and monomer B residues that satisfy the condition 1.1≦V≦40. X / V Y By forming the polyester copolymer into a structure in which two or more macromer units each consisting of a polyester copolymer having, as main structural units, monomer A residues and monomer B residues satisfying the condition (R<0.05)≦40, linked together, the macromer units can be formed into a gradient structure, and as a result, the polyester copolymer has a multi-gradient structure, which is preferable.

[0079] Here, V is the faster initial polymerization rate of monomer A and monomer B. X , and V, the slower of the initial polymerization rates Y can be calculated using the following method. Equimolar amounts of monomer A and monomer B are mixed, and a solvent and catalyst are added as necessary. The temperature and other conditions are adjusted so that the R value is the same as the R value of the polyester copolymer to be synthesized within an error range of 10%, as described below, and the polymerization reaction is initiated. Sampling is carried out periodically from the sample during polymerization, and the remaining amounts of monomer A and monomer B are measured. The remaining amounts are measured, for example, by chromatography or nuclear magnetic resonance (NMR) measurement. The amount of monomer used in the polymerization reaction can be calculated by subtracting the remaining amount from the amount of each monomer charged. When the amount of each monomer used in the polymerization reaction is plotted against the sampling time, the initial slope of the curve is V X and V Y is.

[0080] When the initial polymerization rate of monomer A is faster than that of monomer B, there is a high probability that monomer A will bond to the polymer end during polymerization in the early stages of polymerization. On the other hand, in the later stages of polymerization when monomer A is consumed and its concentration in the reaction solution decreases, there is a high probability that monomer B will bond to the polymer end during polymerization. As a result, a gradient polymer is obtained in which the proportion of monomer A residues gradually decreases from one end. Such a gradient polymer has low crystallinity and suppresses the increase in Young's modulus. To facilitate the formation of such a gradient structure, V X / V Y is more preferably 1.3 or more, and even more preferably 1.5 or more. On the other hand, if the difference in the polymerization rate between the monomer A and the monomer B is too large, the resulting polymer will have a structure similar to a block polymer in which only the monomer A is polymerized and then the monomer B is polymerized, and the resulting polymer will have high crystallinity, which may lead to an increase in the Young's modulus. X / V Y is more preferably 30 or less, even more preferably 20 or less, and even more preferably 10 or less.

[0081] Preferred combinations of such monomer A and monomer B include dilactide and ε-caprolactone, glycolide and ε-caprolactone, glycolide and dilactide, dilactide and dioxepanone, ethylene oxalate and dilactide, dilactide and δ-valerolactone, glycolide and δ-valerolactone, and the like.

[0082] The polymer composition of the present invention contains a polyester copolymer and a biodegradable polymer, and the biodegradable polymer has a melting point of 100°C or higher. The melting point is measured by the same method as that for the polyester copolymer described above. However, when preparing a sample film, if the biodegradable polymer is poorly soluble in chloroform, the solvent may be changed appropriately, or the film may be prepared by a melt molding method such as a hot press method.

[0083] Biodegradability refers to the property of being broken down in the body, and a biodegradable polymer refers to a polymer that has such a property. Terms that can be used interchangeably with biodegradability include bioabsorbability and biocompatibility. Examples of biodegradable polymers include polylactic acid, polyglycolic acid, polydioxanone, polyvalerolactone, polyhydroxybutyrate, polyhydroxyvalerate, polyhydroxyhexanoate, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polytetramethylene adipate terephthalate, polyethylene terephthalate succinate, and polyvinyl alcohol. Copolymers of the above biodegradable polymers may also be used, but in the present invention, they are limited to those with a melting point of 100°C or higher. Furthermore, mixtures of these or mixtures with water-soluble polymers such as polyalkylene glycols may also be used. Among these, polymers selected from polylactic acid, polyglycolic acid, polybutylene succinate, polyhydroxybutyrate, polyhydroxyhexanoate, polyhydroxybutyrate hexanoate and polydioxanone, or mixtures of these, are preferred.

[0084] Polyalkylene glycol is a polymer formed by polymerizing one or more alkylene glycols. Examples of polyalkylene glycols include polyethylene glycol, propylene glycol, and copolymers thereof.

[0085] In order to control the tensile strength within a suitable range, the polymer composition of the present invention contains 0.1% by weight or more and less than 30% by weight of the biodegradable polymer, based on a total of 100% by weight of the polyester copolymer and the biodegradable polymer. The biodegradable polymer content is preferably 0.1% by weight or more and less than 20% by weight, more preferably 0.5 to 15% by weight, and even more preferably 1.0 to 10% by weight.

[0086] The ratio of the tensile strength of the polymer composition to the tensile strength of the polyester copolymer alone is preferably 1.3 or more, more preferably 1.5 or more, and even more preferably 2 or more. If the content of the biodegradable polymer in the polymer composition is too high, the Young's modulus may increase, and the ratio of the Young's modulus of the polymer composition to the Young's modulus of the polyester copolymer alone is preferably 5 or less, more preferably 3 or less, even more preferably 2.5 or less, and most preferably 2 or less.

[0087] The polymer composition of the present invention may also contain a filler, such as inorganic fillers including talc, silica, clay, wollastonite, xonotlite, aluminum borate, mica, glass flakes, carbon black, alumina, ferrite, graphite, carbon nanotubes, graphene, zeolite, hydroxyapatite, β-tricalcium phosphate, α-tricalcium phosphate, calcium carbonate, calcium silicate, magnesium silicate, sodium silicate, potassium titanate, zinc oxide, iron oxide, calcium oxide, magnesium oxide, and titanium oxide, and organic fillers including aramid fiber, carbon fiber, glass fiber, gypsum fiber, and polyester fiber.

[0088] The content of the filler in the polymer composition is not particularly limited, but in order to control the biodegradability within a suitable range, the filler is preferably contained in an amount of 0 to 3 parts by weight, more preferably 0 to 1 part by weight, and even more preferably 0 to 0.1 part by weight, per 100 parts by weight of the total of the polyester copolymer and the biodegradable polymer. Note that, since the less filler the better, an embodiment that does not contain a filler, i.e., an embodiment in which the filler content is 0 part by weight per 100 parts by weight of the total of the polyester copolymer and the biodegradable polymer, is particularly preferred.

[0089] The polymer composition of the present invention preferably has a Young's modulus of 6.3 MPa or less and a tensile strength of 5 MPa or more. Furthermore, in order to control the biotope conformability within a suitable range, the Young's modulus of the polymer composition is more preferably 0.1 to 6.3 MPa. The lower limit of the Young's modulus is more preferably 1.0 MPa or more. The upper limit of the Young's modulus is more preferably 5.0 MPa or less. For the same reasons, the tensile strength of the polymer composition is more preferably 5 to 100 MPa. The lower limit of the tensile strength is more preferably 10 MPa or more, even more preferably 15 MPa or more, particularly preferably 20 MPa or more, and most preferably 30 MPa or more. The upper limit of the tensile strength is more preferably 80 MPa or less, particularly preferably 50 MPa or less.

[0090] The Young's modulus and tensile strength of the polymer composition can be measured according to the method specified in JIS K6251 (2017). Specifically, the polymer composition is dissolved in chloroform to a concentration of 5% by weight, and the solution is transferred to a Teflon petri dish and dried at room temperature under normal pressure for one day. The resulting film is dried under reduced pressure to a thickness of 0.1 mm, which is then cut into strips (30 mm x 5 mm) and measured using a small desktop testing machine EZ-LX (manufactured by Shimadzu Corporation). Initial length: 10mm, Tensile speed: 500 mm / min, Load cell: 1kN A tensile test is carried out under the conditions above to measure the Young's modulus and tensile strength. Each measurement is carried out three times, and the average values ​​are calculated to determine the Young's modulus and tensile strength of the polymer composition.

[0091] The polymer composition of the present invention may contain components other than the polyester copolymer and the biodegradable polymer, as long as the effects of the present invention are not impaired. The total content of the polyester copolymer and the biodegradable polymer in 100% by weight of the polymer composition of the present invention is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, and even more preferably 90 to 100% by weight.

[0092] The polymer composition of the present invention can be suitably used as a molded article made of the polymer composition of the present invention. The molded article of the present invention will be described below.

[0093] The molded article of the present invention is made from the polymer composition of the present invention. In the present invention, the molded article refers to an object obtained by molding the polymer composition of the present invention into various shapes by a conventional method depending on the purpose. Examples of the molded article include membranes, films, and sheets, boards, rods, pipes and tubes, filaments, meshes, bags, woven fabrics, and nonwoven fabrics.

[0094] The polymer composition of the present invention is preferably processed and used as a filament. That is, the filament of the present invention is made of the polymer composition of the present invention. In the present invention, the term "filament" refers to a thread-like body, that is, a thread-like molded body, as described above. The filament is used in the form of a multifilament in which multiple filaments are twisted together to form a single thread, or a monofilament in which a single filament is twisted to form a single thread.

[0095] The polymer composition of the present invention can also be suitably used for medical molded articles. Medical molded articles are the above-mentioned molded articles used for medical purposes. Medical applications include, but are not limited to, sutures, artificial bones, artificial skin, wound dressings, carriers for DDS, microneedles, scaffolding materials for tissue and organ regeneration, and the like.

[0096] The polymer composition of the present invention can be used as a stent. That is, the stent of the present invention is made of the polymer composition of the present invention. Here, a stent is a radially expandable implantable medical device that is implanted inside various body cavities or vessels (e.g., the vascular system, esophagus, gastrointestinal tract, large and small intestines, bile duct, pancreatic duct, lungs, ureters, trachea, etc.). When a body cavity or vessel is narrowed, a stent is placed in the narrowed area to maintain the lumen. Such stents include those that are left in the body cavity or vessel for a long period of time, and those that are retrieved and removed from the body after maintaining the patency of the lumen for a predetermined period of time.

[0097] The polymer composition of the present invention is also preferably used for 3D printer applications. [Example]

[0098] EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0099] (Measurement Example 1: Measurement of the mole fraction and R value of each residue by nuclear magnetic resonance (NMR)) The purified polyester copolymer was dissolved in deuterated chloroform. 1 The ratios of lactic acid monomer residues and caprolactone monomer residues in the polyester copolymer were calculated by H-NMR. 1The H homospin decoupling method was used to determine whether the adjacent monomer residues were lactic acid or caprolactone, and the peak areas were quantified for the methine group of the lactic acid residue (near 5.10 ppm) and the α-methylene group (near 2.35 ppm) and ε-methylene group (near 4.10 ppm) of the caprolactone residue. When δ-valerolactone was used instead of ε-caprolactone, the peak areas were similarly determined for the methine group of the lactic acid residue (near 5.10 ppm) and the α-methylene group (near 2.35 ppm) and δ-methylene group (near 4.10 ppm) of the valerolactone residue.

[0100] From the peak area ratio, [AB] was calculated to obtain the R value. Here, [AB] is the mole fraction of structures in which lactic acid residues and caprolactone or valerolactone residues are adjacent in the copolymer. Specifically, it is the ratio (%) of the total number of AB dyads and BA dyads to the total number of AA dyads, AB dyads, BA dyads, and BB dyads. The results are shown in the table. Device name: JNM-ECZ400R (manufactured by JEOL Ltd.) 1 H homospin decoupling irradiation position: 1.66 ppm Solvent: deuterated chloroform Measurement temperature: room temperature.

[0101] (Measurement Example 2: Measurement of weight average molecular weight by gel permeation chromatography (GPC)) Device name: Prominence (Shimadzu Corporation) Mobile phase: Chloroform (for HPLC) (Wako Pure Chemical Industries, Ltd.) Flow rate: 1mL / min Column: TSKgel GMHHR-M (φ7.8 mm x 300 mm; manufactured by Tosoh Corporation) Detector: UV (254 nm), RI Column and detector temperature: 35°C Standard material: polystyrene The purified polyester copolymer was dissolved in chloroform and passed through a 0.45 μm syringe filter (DISMIC-13HP; manufactured by ADVANTEC) to remove impurities, and then the weight-average molecular weight of the polyester copolymer was calculated by GPC. The results are shown in the table.

[0102] (Measurement Example 3: Measurement of crystallization rate and melting point by differential scanning calorimetry (DSC)) The polyester copolymer or biodegradable polymer was dissolved in chloroform to a concentration of 5 wt%, and the solution was transferred to a Teflon Petri dish and dried overnight at room temperature under atmospheric pressure. This was then dried under reduced pressure to obtain a film approximately 100 μm thick. The resulting film (approximately 10 mg) was placed on an alumina PAN and measured using the DSC method with a differential scanning calorimeter under the following conditions. The crystallization rate was calculated using the following equations 1 and 2 from the melting peak observed between temperature conditions (D) and (E). The temperature at which the melting peak was observed was considered the melting point; if no clear melting peak was observed, the polyester copolymer or biodegradable polymer was deemed to have no clear melting point.

[0103] When multiple melting peaks are observed in a copolymer or the like, the melting point is the sum of the products of the temperatures at which each melting peak is observed and the weight fractions of the monomer residues from which the melting peaks are derived. That is, for example, when multiple melting peaks are observed in a copolymer consisting of monomer A residues and monomer B residues, the melting point of the copolymer can be calculated by {(temperature at which a melting peak derived from monomer A residue is observed) × (weight fraction of monomer A residue in the copolymer) + (temperature at which a melting peak derived from monomer B residue is observed) × (weight fraction of monomer B residue in the copolymer)}.

[0104] Device name: EXSTAR 6000 (Seiko Instruments Inc.) Temperature conditions: (A) 25℃ → (B) 250℃ (10℃ / min) → (C) 250℃ (5min) → (D) -70℃ (10℃ / min) → (E) 250℃ (10℃ / min) → (F) 250℃ (5min) → (G) 25℃ (100℃ / min) Standard material: Alumina Crystallinity ratio of monomer A = (heat of fusion per unit weight of monomer A residue in polyester copolymer) / {(heat of fusion per unit weight of homopolymer consisting of only monomer A residue) × (weight fraction of monomer A residue in polyester copolymer)} × 100 Equation 1 Crystallinity ratio of monomer B = (heat of fusion per unit weight of monomer B residue in polyester copolymer) / {(heat of fusion per unit weight of homopolymer consisting of only monomer B residue) × (weight fraction of monomer B residue in polyester copolymer)} × 100 Equation 2 The heat of fusion per unit weight of a homopolymer can be calculated as follows: A homopolymer consisting only of monomer A residues, which form a polyester copolymer, and a homopolymer consisting only of monomer B residues are prepared. Each homopolymer is dissolved in chloroform to a concentration of 5% by weight. The solution is transferred to a Teflon petri dish and dried overnight at room temperature and atmospheric pressure. This is then dried under reduced pressure to obtain a film. The resulting film is placed on an alumina PAN and measured using a differential scanning calorimeter under the following conditions using the DSC method. The heat of fusion is calculated from the area of ​​the melting peak on the graph, obtained from the measurement results of the melting peak observed between temperature conditions (D) and (E).

[0105] Device name: EXSTAR 6000 (Seiko Instruments Inc.) Temperature conditions: (A) 25℃ → (B) 250℃ (10℃ / min) → (C) 250℃ (5min) → (D) -70℃ (10℃ / min) → (E) 250℃ (10℃ / min) → (F) 250℃ (5min) → (G) 25℃ (100℃ / min) Standard material: alumina.

[0106] (Measurement Example 4: Measurement of Young's modulus and tensile strength by tensile test) The polymer composition was dried under reduced pressure, dissolved in chloroform to a concentration of 5% by weight, and the solution was transferred to a Teflon petri dish and dried at room temperature under normal pressure for 24 hours, followed by further drying under reduced pressure at 50°C for 24 hours to obtain a film.

[0107] The obtained film (approximately 0.1 mm thick) was cut into strips (50 mm x 5 mm) and subjected to a tensile test under the following conditions in accordance with JIS K6251 (2017) to determine the Young's modulus and tensile strength. The results are shown in the table.

[0108] When marking the test specimen, two marks were made on the specimen using an appropriate marker. The test specimen was kept in a relaxed state, and the marks were made accurately and clearly at right angles to the parallel part of the specimen and equidistant from the center of the specimen.

[0109] Device name: EZ-1kNLX (Shimadzu Access) Gauge distance before test: 10 mm Distance between grips: 10 mm (gripped at the position of the marked line) Tensile speed: 500 mm / min Load cell: 1kN.

[0110] (Synthesis Example 1) 50.0 g of L-lactide (PURASORB L; manufactured by PURAC) and 39.6 g of ε-caprolactone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a separable flask as monomers, and 0.45 g of hydroxypivalic acid was used as an initiator. Under an argon atmosphere, 0.27 g of tin(II) octoate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 5.8 mL of toluene (ultra-dehydrated) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a catalyst. The mixture was reacted at 150°C for 9.5 hours to obtain a crude copolymer.

[0111] The resulting crude copolymer was dissolved in 200 mL of chloroform and added dropwise to 3000 mL of hexane under stirring to obtain a precipitate, which was then dried under reduced pressure at 50°C to obtain a macromer.

[0112] 50 g of the macromer, 2.1 g of the catalyst 4,4-dimethylaminopyridinium p-toluenesulfonate (synthetic product), and 0.87 g of 4,4-dimethylaminopyridine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a flask and dissolved in 200 mL of dichloromethane (dehydrated) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) under an argon atmosphere. 1.7 mL of the condensation agent diisopropylcarbodiimide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and condensation polymerization was carried out at room temperature overnight.

[0113] The resulting reaction mixture was diluted with 220 mL of chloroform, and 470 mL of 0.5 M hydrochloric acid was added. After stirring for 30 minutes, the aqueous layer was removed by decantation. This process of adding 470 mL of ion-exchanged water, stirring for 10 minutes, and removing the aqueous layer by decantation was repeated until the pH of the removed aqueous layer reached 7. The remaining organic layer was added dropwise to 2200 mL of stirred methanol to obtain a precipitate. This precipitate was dried under reduced pressure at 50°C to obtain the purified polyester copolymer of Synthesis Example 1.

[0114] (Synthesis Example 2) Synthesis was performed in the same manner as in Synthesis Example 1, except that the amount of toluene was changed to 3.0 mL, the reaction temperature for obtaining the crude copolymer was changed to 140°C, and the amount of 4,4-dimethylaminopyridine was changed to 0.80 g, to obtain a purified polyester copolymer of Synthesis Example 2.

[0115] (Synthesis Example 3) A purified polyester copolymer of Synthesis Example 3 was obtained by performing synthesis in the same manner as in Synthesis Example 1, except that the amount of toluene was changed to 4.2 mL, the amount of 4,4-dimethylaminopyridinium p-toluenesulfonate to 1.8 g, the amount of 4,4-dimethylaminopyridine to 0.60 g, and the amount of diisopropylcarbodiimide to 1.5 mL.

[0116] Example 1 987 mg of the polyester copolymer of Synthesis Example 1 and 13 mg of polylactic acid (Nature3D) were added to a 50 mL screw tube, dissolved in 20 mL of chloroform (Fujifilm Wako Pure Chemical Industries, Ltd.), and dried overnight at room temperature under normal pressure. This was further dried overnight under reduced pressure at 50°C to obtain the polymer composition of Example 1.

[0117] Example 2 A polymer composition of Example 2 was obtained in the same manner as in Example 1, except that the amount of polyester copolymer was changed to 979 mg and the amount of polylactic acid was changed to 21 mg.

[0118] Example 3 The same procedure as in Example 1 was carried out, except that the amount of polyester copolymer was changed to 963 mg and the amount of polylactic acid was changed to 37 mg, to obtain a polymer composition of Example 3.

[0119] Example 4 The same procedure as in Example 1 was carried out except that the amount of polyester copolymer was changed to 877 mg and the amount of polylactic acid was changed to 123 mg, to obtain a polymer composition of Example 4.

[0120] Example 5 A polymer composition of Example 5 was obtained in the same manner as in Example 1, except that polylactic acid (manufactured by Nature3D) was replaced with polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.).

[0121] Example 6 The polymer composition of Example 6 was obtained by the same procedure as in Example 1, except that the amount of polyester copolymer was 979 mg, polylactic acid (manufactured by Nature3D) was changed to polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.), and the amount of polylactic acid was changed to 21 mg.

[0122] Example 7 The polymer composition of Example 7 was obtained by the same procedure as in Example 1, except that the amount of polyester copolymer was 959 mg, polylactic acid (manufactured by Nature3D) was changed to polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.), and the amount of polylactic acid was changed to 42 mg.

[0123] Example 8 The polymer composition of Example 8 was obtained by the same procedure as in Example 1, except that the amount of polyester copolymer was 921 mg, polylactic acid (manufactured by Nature3D) was changed to polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.), and the amount of polylactic acid was changed to 79 mg.

[0124] (Comparative Example 1) 1000 mg of the polyester copolymer of Synthesis Example 1 was placed in a 50 mL screw tube, dissolved in 20 mL of chloroform (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and dried overnight at room temperature under normal pressure, and then dried overnight under reduced pressure at 50°C to obtain a polymer composition of Comparative Example 1.

[0125] (Comparative Example 2) A polymer composition of Comparative Example 2 was obtained in the same manner as in Example 1, except that the amount of polyester copolymer was changed to 594 mg and the amount of polylactic acid was changed to 406 mg.

[0126] (Comparative Example 3) A polymer composition of Comparative Example 3 was obtained in the same manner as in Example 1, except that the amount of polyester copolymer was changed to 498 mg and the amount of polylactic acid was changed to 502 mg.

[0127] Comparative Example 4 The polymer composition of Comparative Example 4 was obtained by the same procedure as in Example 1, except that the amount of polyester copolymer was changed to 700 mg, polylactic acid (manufactured by Nature3D) was changed to polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.), and the amount of polylactic acid was changed to 300 mg.

[0128] (Comparative Example 5) The same procedure as in Example 1 was carried out, except that the amount of polyester copolymer was changed to 980 mg and 13 mg of polylactic acid (Nature3D) was replaced with 20 mg of polycaprolactone (Sigma-Aldrich), to obtain a polymer composition of Comparative Example 5.

[0129] (Comparative Example 6) The polymer composition of Comparative Example 6 was obtained by the same procedure as in Example 1, except that the amount of polyester copolymer was changed to 899 mg and 101 mg of polycaprolactone (Sigma-Aldrich) was used instead of 13 mg of polylactic acid (Nature3D).

[0130] (Comparative Example 7) The polymer composition of Comparative Example 7 was obtained by the same procedure as in Example 1, except that the amount of polyester copolymer was changed to 500 mg and 13 mg of polylactic acid (Nature3D) was replaced with 500 mg of polycaprolactone (Sigma-Aldrich).

[0131] Example 9 The polymer composition of Example 9 was obtained by the same procedure as in Example 1, except that the amount of polyester copolymer was 960 mg, polylactic acid (manufactured by Nature3D) was changed to polybutylene succinate (manufactured by Nature3D), and the amount of polybutylene succinate was changed to 40 mg.

[0132] Example 10 The same procedure as in Example 1 was carried out except that the amount of polyester copolymer was changed to 813 mg and the amount of polylactic acid was changed to 187 mg, to obtain a polymer composition of Example 10.

[0133] Example 11 The polymer composition of Example 11 was obtained in the same manner as in Example 1, except that the polyester copolymer of Synthesis Example 1 was changed to the polyester copolymer of Synthesis Example 2, the amount of the polyester copolymer was changed to 961 mg, and the amount of polylactic acid was changed to 40 mg.

[0134] Example 12 The polymer composition of Example 12 was obtained in the same manner as in Example 1, except that the polyester copolymer of Synthesis Example 1 was changed to the polyester copolymer of Synthesis Example 2, the amount of the polyester copolymer was changed to 900 mg, and the amount of polylactic acid was changed to 100 mg.

[0135] Example 13 The same procedure as in Example 1 was carried out, except that the polyester copolymer of Synthesis Example 1 was changed to the polyester copolymer of Synthesis Example 3, the amount of polyester copolymer was changed to 961 mg, and the amount of polylactic acid was changed to 39 mg, to obtain the polymer composition of Example 13.

[0136] Example 14 The polymer composition of Example 14 was obtained in the same manner as in Example 1, except that the polyester copolymer of Synthesis Example 1 was changed to the polyester copolymer of Synthesis Example 3, the amount of the polyester copolymer was changed to 880 mg, and the amount of polylactic acid was changed to 120 mg.

[0137] (Comparative Example 8) The polymer composition of Comparative Example 8 was obtained by the same procedure as in Example 1, except that the amount of polyester copolymer was 700 mg, polylactic acid (manufactured by Nature3D) was changed to polybutylene succinate (manufactured by Nature3D), and the amount of polybutylene succinate was changed to 300 mg.

[0138] (Comparative Example 9) The polymer composition of Comparative Example 9 was obtained in the same manner as in Comparative Example 1, except that the polyester copolymer of Synthesis Example 1 was changed to the polyester copolymer of Synthesis Example 2.

[0139] (Comparative Example 10) The same procedure as in Comparative Example 1 was carried out, except that the polyester copolymer of Synthesis Example 1 was changed to the polyester copolymer of Synthesis Example 3, to obtain a polymer composition of Comparative Example 10.

[0140] The polymer compositions of Examples 1 to 14 and Comparative Examples 1 to 10 were subjected to the measurements described in Measurement Examples 1 to 4. The results are shown in the table. However, since film production was not possible for Comparative Example 8, the evaluation of Measurement Example 4 could not be carried out.

[0141] [Table 1]

[0142] [Table 2]

[0143] The ratio of monomer A residues in the table indicates the molar ratio of monomer A residues relative to the total number of moles of monomer A residues and monomer B residues, which is 100%.

[0144] In the table, Mw indicates the weight average molecular weight. [Industrial Applicability]

[0145] Specific applications of the polymer composition of the present invention include fibers such as nonwoven fabrics, containers for disposable toiletries and cosmetics, and films such as packaging films, agricultural mulch films, and tapes. Other potential medical applications include sutures, artificial bones, artificial skin, wound dressings, carriers for DDS, microneedles, and scaffolding materials for tissue and organ regeneration. Other potential applications include binders for toners and thermal transfer inks, and 3D printer applications, but are not limited to these.

Claims

1. A polymer composition comprising a polyester copolymer and a biodegradable polymer, The polyester copolymer has two types of ester bond-forming monomer residues as main structural units, The polyester copolymer satisfies the following (1) to (3), where the two types of ester bond-forming monomers are designated as "monomer A" and "monomer B," respectively: the monomer A is a compound selected from the group consisting of lactic acid, glycolic acid, dilactide, and glycolide; the monomer B is a compound selected from the group consisting of hydroxyvaleric acid, hydroxycaproic acid, valerolactone, and caprolactone; The biodegradable polymer has a melting point of 100°C or higher, the biodegradable polymer is a polymer selected from polylactic acid, polyglycolic acid, polybutylene succinate, polyhydroxybutyrate, polyhydroxyhexanoate, polyhydroxybutyrate hexanoate, and polydioxanone, or a mixture thereof; A polymer composition comprising the biodegradable polymer in an amount of 0.1% by weight or more and less than 30% by weight, based on a total of 100% by weight of the polyester copolymer and the biodegradable polymer. (1) The R value is 0.45 or more and 0.99 or less. R = [AB] / (2 [A] [B]) × 100 [A]: mole fraction (%) of monomer A residue in the polyester copolymer [B]: mole fraction (%) of monomer B residue in the polyester copolymer [AB]: mole fraction (%) of structures in which monomer A residue and monomer B residue are adjacent to each other (A-B and B-A) in the polyester copolymer. (2) The crystallinity of the monomer A residue and the crystallinity of the monomer B residue are less than 14%. (3) The melting point is less than 100°C or does not have a clear melting point.

2. The polymer composition according to claim 1, wherein the monomer A is lactic acid, the monomer B is caprolactone, and the biodegradable polymer is a polymer selected from polylactic acid and polybutylene succinate.

3. 3. The polymer composition according to claim 1, further comprising 0 to 3 parts by weight of a filler per 100 parts by weight of the total of the polyester copolymer and the biodegradable polymer.

4. 4. The polymer composition according to claim 1, wherein the polyester copolymer has a weight average molecular weight of 60,000 or more.

5. 5. The polymer composition according to claim 1, wherein the polymer composition has a Young's modulus of 6.3 MPa or less and a tensile strength of 5 MPa or more.

6. The polyester copolymer has a structure in which two or more macromer units are linked together, The faster initial polymerization rate of the monomer A and the monomer B is V Ｘ , the slower initial polymerization rate is V Ｙ In this case, the macromer unit satisfies the condition 1.1≦V Ｘ / V Ｙ 6. The polymer composition according to claim 1, wherein the main structural units are residues of monomer A and residues of monomer B satisfying a ratio of ≦40.

7. 7. The polymer composition according to claim 1, wherein the total amount of the polyester copolymer and the biodegradable polymer is 50 to 100% by weight, based on 100% by weight of the polymer composition.

8. A molded article comprising the polymer composition according to any one of claims 1 to 7.

9. A filament comprising the polymer composition according to any one of claims 1 to 7.

10. A stent comprising the polymer composition according to any one of claims 1 to 7.

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