Polymer composition and molded body

Abstract

A polymer composition which is a polymer composition containing a polyester copolymer and a biodegradable polymer, the polyester copolymer having 2 ester bond-forming monomer residues as main constitutional units, the polyester copolymer satisfying (1) to (3) below in the case where the 2 ester bond-forming monomers are respectively designated as "monomer A" and "monomer B", the biodegradable polymer having a melting point of 100°C or higher, and the biodegradable polymer being contained at 0.1% by mass or more and less than 30% by mass in the total 100% by mass of the polyester copolymer and the biodegradable polymer. A polymer composition having a low Young's modulus and a high tensile strength is provided.(1) The R value is 0.45 or more and 0.99 or less. R = [AB] / (2[A][B]) x 100 [A]: Molar fraction (%) of monomer A residue in the polyester copolymer [B]: Molar fraction (%) of monomer B residue in the polyester copolymer [AB]: Molar fraction (%) of structure (A-B and B-A) in which monomer A residue and monomer B residue are contiguous(2) The crystallization rate of monomer A residue and monomer B residue is less than 14%.(3) The melting point is less than 100°C or no definite melting point is present.

Description

TECHNICAL FIELD

[0001] The present application relates to a polymer composition containing a polyester copolymer and a biodegradable polymer. BACKGROUND

[0002] Polymers produced from ester bond-forming monomers, represented by polylactic acid, polyglycolic acid, polycaprolactone or copolymers thereof, are attracting attention as biodegradable or bioabsorbable polymers, and have been utilized in various fields such as medical materials such as sutures, slow-release materials for medicines, agricultural chemicals, fertilizers, and the like.

[0003] However, biodegradable polymers and bioabsorbable polymers produced from ester bond-forming monomers are generally fragile. Therefore, various copolymers have been developed in an attempt to obtain biodegradable polymers having practical strength and moldability that can withstand practical use, for the purpose of improving mechanical properties.

[0004] For example, as a biodegradable / bioabsorbable polymer having low Young's modulus and high tensile strength, a polyester copolymer having a residue of two ester bond-forming monomers ("monomer A" and "monomer B") as a main structural unit, a value R represented by the following formula of 0.45 or more and 0.99 or less, and a crystallization rate of at least one of the monomer A residue or the monomer B residue of less than 14% has been proposed (for example, see Patent Document 1)

[0005] R = [AB] / (2[A][B]) x 100

[0006] [A]: Molar fraction (%) of monomer A residue in the polyester copolymer

[0007] [B]: Molar fraction (%) of monomer B residue in the polyester copolymer

[0008] [AB]: Molar fraction (%) of structures in which the monomer A residue and the monomer B residue are adjacent to each other in the polyester copolymer.

[0009] In addition, attempts to improve mechanical properties by mixing a plurality of biodegradable polymers have also been implemented. For example, as a composition improved in strength, flexibility, elongation, toughness, and the like, the following composition has been proposed: a biodegradable polymer blend that is a polymer blend including a hard synthetic biodegradable polymer and a soft synthetic biodegradable polymer, and that has higher strength and / or elongation than the biodegradable polymer itself (see, for example, Patent Literature 2); a resin composition containing polylactic acid, L-lactide / ε-caprolactone copolymer, and a filler (see, for example, Patent Literature 3); a blend of poly-D-lactic acid and L-lactide / ε-caprolactone copolymer, or a blend of poly-L-lactic acid and D-lactide / ε-caprolactone copolymer (see, for example, Patent Literature 4); and the like.

[0010] Prior Art Documents

[0011] Patent Literature

[0012] Patent Literature 1: International Publication No. 2019 / 35357

[0013] Patent Literature 2: Japanese Patent Application Publication No. 2008-255349

[0014] Patent Literature 3: Japanese Patent Application Publication No. 2017-179234

[0015] Patent Literature 4: Japanese Patent Application Laid-Open No. 2020-529483 SUMMARY

[0016] PROBLEMS TO BE SOLVED BY THE INVENTION

[0017] It is known that polylactic acid and polyglycolic acid generally have high crystallinity, and have a property of being hard and having a high Young's modulus. However, these polymers lack softness, and have poor biocompatibility required for medical materials. In addition, it has been reported that they hinder surrounding tissues when embedded in the body, or become a cause of protrusion accidents, due to their hardness.

[0018] Therefore, research has been conducted to impart softness by copolymerizing polycaprolactone with these polymers. The multi-gradient polymer described in Patent Literature 1 has a low Young's modulus, and is improved in softness, which has been a problem in the past, and is suitable for filling materials and coating materials. On the other hand, when used in applications requiring followability to large deformations such as joint transplantation, the tensile strength is insufficient, and further improvement is required.

[0019] In addition, the resin compositions described in Patent Literatures 2 to 4 have a high Young's modulus, and have poor biocompatibility and moldability, and thus a material having a low Young's modulus is required.

[0020] In view of the above problems, an object of the present application is to provide a polymer composition having a low Young's modulus and a high tensile strength.

[0021] Means for solving the problems

[0022] The present application for solving the above problems is as follows.

[0023] A polymer composition which is a polymer composition containing a polyester copolymer and a biodegradable polymer,

[0024] The polyester copolymer has 2 ester bond-forming monomer residues as main structural units,

[0025] In a case where the 2 ester bond-forming monomers are respectively "monomer A" and "monomer B", the polyester copolymer satisfies the following (1) to (3),

[0026] The biodegradable polymer has a melting point of 100°C or higher,

[0027] In 100% by weight of the total of the polyester copolymer and the biodegradable polymer, the biodegradable polymer is contained in an amount of 0.1% by weight or more and less than 30% by weight,

[0028] (1) the R value is 0.45 or more and 0.99 or less;

[0029] R = [AB] / (2[A][B]) x 100

[0030] [A]: Molar fraction (%) of monomer A residue in the polyester copolymer

[0031] [B]: Molar fraction (%) of monomer B residue in the polyester copolymer

[0032] [AB]: Molar fraction (%) of structure (A-B and B-A) in which monomer A residue and monomer B residue are adjacent to each other in the polyester copolymer;

[0033] (2) the crystallization rate of monomer A residue and the crystallization rate of monomer B residue are less than 14%;

[0034] (3) the melting point is less than 100°C or does not have a definite melting point.

[0035] Effects of the Invention

[0036] By the present application, a polymer composition having a low Young's modulus, biodegradability or bioabsorbability, and an excellent tensile strength, which is suitable for medical use, elastomer use, can be obtained. DETAILED DESCRIPTION

[0037] The polymer composition of the present application contains a polyester copolymer and a biodegradable polymer. The polyester copolymer is a copolymer having two ester bond-forming monomer residues as main constitutional units. In the present specification, the two ester bond-forming monomers are sometimes referred to as "monomer A" and "monomer B", respectively. In addition, the monomer residues from "monomer A" and "monomer B" in the copolymer formed from "monomer A" and "monomer B" are sometimes referred to as "monomer A residue" and "monomer B residue", respectively.

[0038] The "ester bond-forming monomer" means a monomer that gives a polymer in which monomer units are linked by ester bonds, i.e., a polyester, by polymerization of the monomer.

[0039] As the ester bond-forming monomer, a hydroxy carboxylic acid is preferably used. In addition, a lactone of a cyclic compound obtained by intramolecular dehydration condensation of a hydroxy group and a carboxy group of a hydroxy carboxylic acid, and a propiolactone of a cyclic compound obtained by dehydration condensation of a hydroxy group and a carboxy group of two molecules of a hydroxy carboxylic acid with each other can also be preferably used.

[0040] As the hydroxy carboxylic acid, an aliphatic hydroxy carboxylic acid is particularly preferably used. As the aliphatic hydroxy carboxylic acid, lactic acid, glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxyhexanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxynonanoic acid, hydroxydecanoic acid, hydroxyundecanoic acid, hydroxydodecanoic acid, (2-hydroxyethoxy)acetic acid, and the like can be given. A compound selected from the group consisting of lactic acid, glycolic acid, hydroxyvaleric acid, and hydroxyhexanoic acid is particularly preferably used.

[0041] As the lactic acid, any of L-lactic acid, D-lactic acid, and a mixture thereof can be used, and L-lactic acid is preferably used from the viewpoint of the physical properties and biocompatibility of the resulting polymer. In the case where a mixture is used as the monomer, the content of L-form is preferably 85% or more, and more preferably 95% or more.

[0042] As the lactone, butyrolactone, valerolactone, caprolactone, dioxepanone, ethylene oxalate, p-dioxanone, trimethylene carbonate, β-propiolactone, pivalolactone, and the like can be used. Butyrolactone, valerolactone, caprolactone, p-dioxanone, trimethylene carbonate are particularly preferably used, and valerolactone or caprolactone is more preferably used.

[0043] As the propiolactone, a propiolactone obtained by dehydration condensation of two molecules of lactic acid, a glycolide obtained by dehydration condensation of two molecules of glycolic acid, tetramethyl glycolide, and the like can be used, and a propiolactone or a glycolide is particularly preferably used.

[0044] As the ester bond-forming monomer, a derivative of the above exemplified monomer can also be used.

[0045] Among them, the present application is more preferably monomer A and monomer B are each a monomer formed from a compound selected from the group consisting of lactic acid, glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxyhexanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxynonanoic acid, hydroxydecanoic acid, hydroxyundecanoic acid, hydroxydodecanoic acid, (2-hydroxyethoxy) acetic acid, butyrolactone, valerolactone, caprolactone, dioxepanone, ethyloxalate, p-dioxanone, trimethylene carbonate, β-propiolactone, pivalolactone, lactide, glycolide and tetramethyl glycolide. Monomer A is more preferably a compound selected from the group consisting of lactic acid, glycolic acid, lactide, 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, hydroxyhexanoic acid, valerolactone, caprolactone, and is particularly preferably caprolactone or δ-valerolactone.

[0046] In the present specification, the monomer having higher crystallinity among the two ester bond monomers is referred to as monomer A, and the monomer having lower crystallinity is referred to as monomer B.

[0047] The crystallinity of the homopolymer is measured by the DSC method using a differential scanning calorimeter as described above. For example, the heat of fusion per unit weight of a homopolymer composed only of lactic acid residues is 135 J / g, and the heat of fusion per unit weight of a homopolymer composed only of caprolactone residues is 51 J / g. That is, in the case where the polyester copolymer has lactic acid residues and caprolactone residues as the main constitutional units, lactic acid becomes monomer A and caprolactone becomes monomer B.

[0048] In the present application, the crystallization rate of monomer A residues and the crystallization rate of monomer B residues in the polyester copolymer are each less than 14%. If the crystallization rate is less than 14%, the increase in Young's modulus can be suppressed, and a polymer composition suitable for medical materials and elastomer applications can be obtained. The crystallization rate of monomer A residues and monomer B residues is preferably 10% or less, and more preferably 5% or less.

[0049] The crystallization rate of monomer residues referred to herein is the proportion of the heat of fusion per unit weight of the monomer residues in the polyester copolymer, with respect to the product of the heat of fusion per unit weight of a homopolymer composed only of the monomer residues and the weight fraction of the monomer residues in the polyester copolymer.

[0050] That is, the crystallization rate of monomer A residues is the proportion of the heat of fusion per unit weight of monomer A residues in the polyester copolymer, with respect to the product of the heat of fusion per unit weight of a homopolymer composed only of monomer A and the weight fraction of monomer A residues in the polyester copolymer. The crystallization rate of monomer A residues and monomer B residues each indicates the proportion of the monomer A residues or monomer B residues in the polyester copolymer that form a crystalline structure.

[0051] When the monomer A residue is a lactic acid residue and the monomer B residue is a caprolactone residue, the crystallization rate of the lactic acid residue and the caprolactone residue is preferably less than 14%, more preferably 10% or less.

[0052] Specifically, the crystallization rate is calculated from the following method.

[0053] The polyester copolymer was dissolved in chloroform at a concentration of 5% by weight, and the solution was transferred to a Teflon flat plate and dried at normal pressure and room temperature for one day. The polyester copolymer film was obtained by drying under reduced pressure. The obtained polyester copolymer film was collected in an alumina PAN, and the melting heat was calculated from the measurement result of the melting peak observed between the following temperature conditions (D) to (E) by DSC method under the following conditions using a differential scanning calorimeter.

[0054] Apparatus name: EXSTAR 6000 (manufactured by Seiko Instruments Inc.)

[0055] Temperature conditions: (A) 25°C→(B) 250°C (10°C / min)→(C) 250°C (5 min)→(D) -70°C (10°C / min)→(E) 250°C (10°C / min)→(F) 250°C (5 min)→(G) 25°C (100°C / min)

[0056] Standard substance: alumina

[0057] Here, the above temperature conditions mean that the temperature is increased from 25°C to 250°C at a rate of 10°C / min (1st stage), the temperature is decreased to -70°C at a rate of 10°C / min after the temperature is maintained at 250°C for 5 min, and the temperature is increased to 250°C at a rate of 10°C / min again (2nd stage), and the temperature is decreased to 25°C at a rate of 100°C / min after the temperature is maintained at 250°C for 5 min. That is, the melting peak observed between the temperature conditions (D) to (E) means the melting peak at the temperature increase of the 2nd stage (the same applies hereinafter).

[0058] Next, a homopolymer composed only of the monomer A residue and a homopolymer composed only of the monomer B residue were each prepared from the polyester copolymer. The crystallinity of each homopolymer was measured in the same manner as the measurement of the polyester copolymer using a differential scanning calorimeter (DSC).

[0059] The crystallization rate was calculated from the following equation.

[0060] Crystallization rate of monomer A residue = (melting heat per unit weight of monomer A residue of the polyester copolymer) / {(melting heat per unit weight of the homopolymer composed only of the monomer A residue) x (weight fraction of the monomer A residue in the polyester copolymer)} x 100 (%)

[0061] Crystallization rate of monomer B residue = (heat of fusion per unit weight of monomer B residue of the polyester copolymer) / {(heat of fusion per unit weight of homopolymer consisting only of monomer B residue) x (weight fraction of monomer B residue in the polyester copolymer)} x 100 (%)

[0062] In the present specification, the "monomer residue" refers to, in principle, a repeating unit from the chemical structure of the monomer in the chemical structure of a copolymer obtained by polymerizing 2 or more kinds of monomers including the monomer. For example, in the case where lactic acid (CH3CH(OH)COOH) and caprolactone (ε-caprolactone: the following formula) are polymerized to obtain a copolymer of lactic acid and caprolactone,

[0063]

[0064] The unit represented by the above formula R1 is a lactic acid monomer residue, and the unit represented by the following formula is a caprolactone monomer residue.

[0065]

[0066] Note that, as an exception, in the case where a dimer such as lactide is used as a monomer, the "monomer residue" refers to one of the 2 repeating structures from the dimer. For example, in the case where lactide (L-(-)-lactide: the following formula) and caprolactone are polymerized, in the chemical structure of the copolymer, as a monomer residue from lactide, a structure represented by the above formula (R1), that is, a structure in which a lactic acid residue is repeated twice, is formed, and in this case, one of the lactic acid residues is understood to be a "monomer residue". That is, it is considered that 2 lactic acid residues as "monomer residues" are formed from lactide as a monomer.

[0067]

[0068] The "two kinds of monomer residues as the'main structural units'" means that the sum of the amounts of the two kinds of monomer residues is 50 mol% or more, based on the sum of the amounts of all the monomer residues contained in the entire polymer including other monomer residues, and each of the residues is 20 mol% or more, based on the sum of the amounts of all the monomer residues contained in the entire polymer. For example, the "monomer A residue and monomer B residue as the main structural units" means that the sum of the amounts of the monomer A residue and the monomer B residue is 50 mol% or more, based on the sum of the amounts of all the monomer residues contained in the entire polymer, and the monomer A residue is 20 mol% or more and the monomer B residue is 20 mol% or more. Here, the molar fractions of the monomer A residue, the monomer B residue, and other residues can be determined by the area values of the signals from each residue by nuclear magnetic resonance (NMR) measurement. For example, in the case where the monomer A residue is a lactic acid residue and the monomer B residue is a caprolactone residue, the measurement can be performed by the method described in Measurement Example 1 described later.

[0069] The sum of the monomer A residue and the monomer B residue is preferably 75 mol% or more, more preferably 90 mol% or more, based on the sum of the amounts of all the monomer residues contained in the entire polymer including other monomer residues. In addition, each of the monomer A residue and the monomer B residue is preferably 30 mol% or more, more preferably 40 mol% or more, based on the sum of the amounts of all the monomer residues contained in the entire polymer. As a particularly preferable mode, the sum of the monomer A residue and the monomer B residue is 100 mol% of the entire polymer, that is, the polymer is composed of only the monomer A and the monomer B.

[0070] Note that other monomers copolymerizable with the two kinds of ester bond-forming monomers constituting the main structural units can be further copolymerized without impairing the effects of the present application. As such monomers, monomers other than the monomer A and the monomer B among the above-described ester bond-forming monomers can be used.

[0071] In addition, a mode in which a monomer functioning as a linker is copolymerized is also a preferable mode. As the monomer functioning as a linker, a hydroxy carboxylic acid, a dihydric alcohol, a dicarboxylic acid, an amino acid, a diamine, a diisocyanate, a diepoxide, or the like different from the two kinds of ester bond-forming monomers constituting the main structural units can be exemplified.

[0072] Note that in the present specification, a copolymer in which a structural unit linked by a bond other than an ester bond is included in a part by including a monomer other than an ester bond-forming monomer in a structural unit is also described as a "polyester copolymer".

[0073] The polyester copolymer preferably has biodegradability or bioabsorbability. Those skilled in the art can suitably combine the monomers exemplified above, and additionally adjust the amount ratio of the monomers within the range specified in the present application, whereby a copolymer exhibiting appropriate biodegradability or bioabsorbability is synthesized according to the use.

[0074] The polyester copolymer has a melting point of less than 100°C or does not have a definite melting point. The melting point can be measured using a melting point measuring device, DSC, and is preferably measured using DSC. In the case of measurement using DSC, specifically, the melting point is obtained by the following method.

[0075] The polyester copolymer is dissolved in chloroform at a concentration of 5% by weight, and the solution is transferred to a Teflon flat plate and dried at normal pressure and room temperature for one day. It is dried under reduced pressure to obtain a polyester copolymer film. The obtained polyester copolymer film is collected in an alumina PAN, and measured by DSC method under the following conditions using a differential scanning calorimeter, and the temperature of the melting peak observed between the following temperature conditions (D) to (E) is taken as the melting point. In the case where no definite melting peak is observed in this range, it is considered to have no definite melting point.

[0076] Apparatus name: EXSTAR 6000 (manufactured by Seiko Instruments Inc.)

[0077] Temperature conditions: (A) 25°C→(B) 250°C (10°C / min)→(C) 250°C (5 min)→(D) -70°C (10°C / min)→(E) 250°C (10°C / min)→(F) 250°C (5 min)→(G) 25°C (100°C / min)

[0078] Standard substance: alumina

[0079] In the polyester copolymer described above, if one monomer is excessively present in terms of the molar ratio of the monomer A residue to the monomer B residue, the properties approach those of a homopolymer, and therefore, the molar ratio of the monomer A residue is preferably 20 to 80%, more preferably 30 to 70%, and further preferably 40 to 60%, relative to 100% of the total moles of the monomer A residue and the monomer B residue described above.

[0080] In the polyester copolymer described above, in the case where the two ester bond-forming monomers are respectively designated as "monomer A" and "monomer B", the R value represented by the following formula is 0.45 or more and 0.99 or less.

[0081] R = [AB] / (2[A][B]) x 100

[0082] [A]: Molar fraction (%) of monomer A residue in the polyester copolymer

[0083] [B]: Molar fraction (%) of monomer B residue in the polyester copolymer

[0084] [AB]: Molar fraction (%) of structure (A-B and B-A) in which monomer A residue and monomer B residue are adjacent to each other in the polyester copolymer

[0085] The R value can be used as an index indicating the randomness of the arrangement of the monomer residues in the copolymer in which two ester bond-forming monomer residues, i.e., monomer A residue and monomer B residue, are used as the main structural unit. For example, in a random copolymer in which the monomer arrangement is completely random, the R value becomes 1.

[0086] The R value can be determined by quantifying the proportions of A-A, B-B, A-B, and B-A among combinations of two adjacent monomer residues (hereinafter sometimes referred to as dyads) by nuclear magnetic resonance (NMR) measurement. Specifically, it is determined by the method described in Measurement Example 1 described later. For example, in the case where the polyester copolymer is composed of only monomer A and monomer B, the so-called [AB] refers to the proportion of the total number of A-B dyads and B-A dyads with respect to the total number of all dyads (A-A, B-B, A-B, B-A) in the polyester copolymer. In addition, for example, in the case where the polyester copolymer is composed of three components of monomer A, monomer B, and monomer C, the so-called [AB] refers to the proportion of the total number of A-B dyads and B-A dyads with respect to the total number of all dyads (A-A, B-B, A-B, B-A, A-C, C-A, B-C, C-B, C-C) in the polyester copolymer. The same applies to the case where the polyester copolymer is composed of four or more kinds of monomers.

[0087] If the R value is less than 0.45, the crystallinity of the polyester copolymer is high, and sometimes the obtained molded article becomes hard and the Young's modulus increases. On the other hand, if the R value is greater than 0.99, sometimes the obtained molded article becomes excessively soft and becomes tacky, and the handleability decreases. 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 further preferably 0.50 to 0.80.

[0088] In order to control the tensile strength within an appropriate range, the weight average molecular weight of the above-described polyester copolymer is preferably 60,000 or more, more preferably 100,000 or more, and further preferably 150,000 or more. The upper limit is not particularly specified, but in order to control the molding processability within an appropriate range, the weight average molecular weight is preferably 1,000,000 or less, more preferably 800,000 or less, and further preferably 500,000 or less. The weight average molecular weight of the polyester copolymer can be determined by, for example, the method described in Measurement Example 2.

[0089] As an example, the above-described polyester copolymer can be manufactured by a polyester copolymer manufacturing method having the following procedures:

[0090] In the macromonomer synthesis procedure, monomer A and monomer B, which are the two ester bond-forming monomers, are mixed and polymerized in such amounts that the sum of the monomer A residues and the monomer B residues in the polyester copolymer obtained at the end of the polymerization is 50 mol% or more of the total residues, and each of the monomer A residues and the monomer B residues is 20 mol% or more of the total residues.

[0091] In the polymerization procedure, the macromonomers obtained in the above-described macromonomer synthesis procedure are linked to each other, or the above-described monomer A and the above-described monomer B are additionally added to a macromonomer solution obtained in the above-described macromonomer synthesis procedure and further polymerized, thereby performing the polymerization.

[0092] 〔Macromonomer synthesis procedure〕

[0093] In the macromonomer synthesis procedure, monomer A and monomer B are mixed and polymerized in such amounts that the sum of the monomer A residues and the monomer B residues in the polyester copolymer obtained at the end of the polymerization is 50 mol% or more of the total residues, and each of the monomer A residues and the monomer B residues is 20 mol% or more of the total residues. Thereby, a polyester copolymer having monomer A residues and monomer B residues as the main structural units can be obtained, but in the present manufacturing method, the above-described polymerization procedure is further performed, and therefore, in the present specification, the polyester copolymer obtained by the present procedure is described as a "macromonomer".

[0094] As the ester bond-forming monomers, the above-described ester bond-forming monomers can be used, and the above-described description is also applicable to the preferred combinations and the like.

[0095] The randomness of the distribution of the monomer residues constituting the polyester copolymer having the two ester bond-forming monomer residues as the main structural units varies depending on the reactivity of each monomer at the time of polymerization. That is, at the time of polymerization, if the same monomer and the other monomer are bonded with the same probability after one of the two monomers, a copolymer in which the monomer residues are completely randomly distributed can be obtained. However, in the case where either of the monomers has a tendency to be easily bonded after one of the monomers, a gradient copolymer in which the distribution of the monomer residues is uneven can be obtained. The obtained gradient copolymer has a continuous change in the composition of the monomer residues along the molecular chain from the end of the polymerization start to the end of the polymerization end.

[0096] Here, if monomer A is assumed to be a monomer whose initial polymerization rate is greater than that of monomer B, in the case where monomer A and monomer B are subjected to copolymerization in the macromonomer synthesis step, monomer A is easily bonded after monomer A. Therefore, in the synthesized macromonomer, a gradient structure is formed, which forms a composition gradient in which the proportion of monomer A units gradually decreases from the starting end to the ending end of polymerization. That is, the macromonomer obtained by the present procedure becomes a macromonomer having a gradient structure in which monomer A residues and monomer B residues form a composition gradient in the backbone, due to the difference in the initial polymerization rate of monomer A and monomer B. That is, by using monomer A and monomer B having different initial polymerization rates in the present procedure, a macromonomer having a gradient structure in which a composition gradient is formed in the backbone can be obtained. In the present specification, such a macromonomer is sometimes referred to as a "gradient macromonomer".

[0097] In the macromonomer synthesis step, in order to realize such a gradient structure, it is desirable to synthesize the macromonomer by a polymerization reaction that proceeds in one direction from the starting end. As such a synthesis reaction, a reaction using ring-opening polymerization or living polymerization can be given as a preferable example.

[0098] In order to easily produce a polyester copolymer that finally satisfies the above R value, the macromonomer obtained by the present procedure preferably has the same R value as the polyester copolymer, that is, the R value represented by the following formula is preferably 0.45 or greater and 0.99 or less, and more preferably 0.50 or greater and 0.80 or less.

[0099] R = [AB] / (2[A][B]) x 100

[0100] [A]: Molar fraction (%) of monomer A residues in the macromonomer

[0101] [B]: Molar fraction (%) of monomer B residues in the macromonomer

[0102] [AB]: Molar fraction (%) of structures in which monomer A residues and monomer B residues are adjacent (A-B and B-A) in the macromonomer

[0103] The weight average molecular weight of the macromonomer synthesized by the macromonomer synthesis step is preferably 10,000 or greater, and more preferably 20,000 or greater. In addition, in order to suppress crystallinity and ensure flexibility, the weight average molecular weight of the macromonomer is preferably 150,000 or less, and more preferably 100,000 or less.

[0104] 〔Polymerization Step〕

[0105] In the polymerization process, multiple macromonomers obtained through the macromonomer synthesis process are linked together, or monomers A and B are added to the macromonomer solution obtained through the macromonomer synthesis process and further polymerized, thereby achieving polymerization. In this process, macromonomers obtained through one macromonomer synthesis process can be linked together, or multiple macromonomers obtained through two or more macromonomer synthesis processes can be linked together. It should be noted that "polymerization" refers to the formation of a polyester copolymer with the following structure: a structure formed by linking multiple macromonomer units with a gradient structure in which monomer A residues and monomer B residues have a compositional gradient in the backbone.

[0106] The number of polymerized macromonomer units should be 2 or more. A higher number of linkages leads to increased tensile strength through molecular chain entanglement; therefore, 3 or more is preferred, 4 or more is more preferred, and 6 or more is even more preferred. On the other hand, if the molecular weight of the polyester copolymer increases excessively, there is a concern that the increased viscosity may negatively impact moldability. Therefore, the number of macromonomer units is preferably 80 or less, more preferably 40 or less, and even more preferably 20 or less.

[0107] The number of links between macromonomer units can be adjusted by the catalyst and reaction time used in the polymerization process. When polymerizing by linking macromonomers together, the number of macromonomer units can be determined by dividing the weight-average molecular weight of the final polyester copolymer by the weight-average molecular weight of the macromonomers.

[0108] The aforementioned polyester copolymer can be a linear polymer formed by the linear linkage of macromolecular monomer units, or a branched polymer formed by the branching linkage of macromolecular monomer units.

[0109] Linear polyester copolymers can be synthesized, for example, by bonding the same gradient macromonomers one molecule at a time to each other at both ends via end-to-end bonding.

[0110] Polyester copolymers can be obtained by polymerizing macromonomers with hydroxyl and carboxyl groups at both ends, by using a condensing agent to condense the ends together. 4,4-Dimethylaminopyridine p-toluenesulfonic acid can be used as a condensing agent. 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, N,N'-carbonyldiimidazole, 1,1'-carbonylbis(1,2,4-triazole), 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholine = chloride n hydrate, trifluoromethanesulfonic acid (4,6-dimethoxy-l,3,5-triazin-2-yl)-(2- octyloxy-2-oxoethyl)dimethylammonium, lH-benzotriazol-l-yloxytris(dimethylamino) hexafluorophosphate, lH-benzotriazol-l-yloxytripyrrolidinophosphonium hexafluorophosphate, (7-azabenzotriazol-l-yloxy)tripyrrolidinophosphonium hexafluorophosphate, chlorotripyrrolidinophosphonium hexafluorophosphate, bromotris(dimethylamino)phosphonium hexafluorophosphate, 3-(diethoxyphosphoryloxy)-l,2,3-benzotriazin-4(3H)-one, O- (benzotriazol-l-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, O-(7-azabenzotriazol-l-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-l,2,3-benzotriazin-3-yl)-N,N,N',N'- tetramethyluronium tetrafluoroborate, S-(l-oxide-2-pyridyl)-N,N,N',N'-tetramethylthiuronium tetrafluoroborate, O-[2-oxo-l(2H)-pyridyl]-N,N,N',N'-tetramethyluronium tetrafluoroborate, {{[(l-cyano-2-ethoxy-2-oxoethylidene)amino]oxy}-4- morpholinomethylene}dimethylammonium hexafluorophosphate, 2-chloro-l,3- dimethylimidazolinium hexafluorophosphate, l-(chloro-l-pyrrolidinylmethylene)pyrrolidinium hexafluorophosphate, 2-fluoro-l,3-dimethylimidazolinium hexafluorophosphate, fluoro-N,N,N',N'-tetramethylformamidinium hexafluorophosphate, and the like.

[0111] In addition, in the case where the polymerization reaction is active, i.e., in the case where the polymerization reaction can be continuously started from the end of the polymer, the operation of supplementing the monomer A and the monomer B to the gradient macromonomer solution after the polymerization reaction is completed and further polymerizing can be repeatedly performed, whereby the polymericization is performed.

[0112] Alternatively, the gradient macromonomers can also be polymerized with each other via a linker without affecting the mechanical properties of the polymer. In particular, if a linker having a plurality of carboxyl groups and / or a plurality of hydroxyl groups, such as 2,2-bis(hydroxymethyl)propionic acid, is used, a branched chain-like polyester copolymer in which the linker becomes a branching point can be synthesized.

[0113] The polyester copolymer obtained by the production method described above is a copolymer having a structure in which two or more macromonomer units having a composition gradient of monomer A residues and monomer B residues are linked. This is a preferred form of the polyester copolymer of the present application. In the present specification, such a structure is sometimes referred to as "multi-gradient" and a copolymer having a multi-gradient structure is sometimes referred to as "multi-gradient copolymer". That is, the polyester copolymer described above is preferably a multi-gradient copolymer.

[0114] The polyester copolymer preferably has a structure in which two or more macromonomer units are linked, and more preferably has a structure in which three or more macromonomer units are linked. In addition, as an upper limit of the number of macromonomer units linked, 80 or less, more preferably 40 or less, and further preferably 20 or less is preferable.

[0115] As described above, a polyester copolymer in which the monomer A residues are lactic acid residues and the monomer B residues are caprolactone residues is a particularly preferred form of the present application. Such a polyester copolymer is preferably produced by the production method described below.

[0116] First, in the macromonomer synthesis step, lactide and ε-caprolactone are polymerized in the presence of a catalyst. In order to remove impurities before use, the lactide and the ε-caprolactone are preferably purified. The purification of the lactide can employ recrystallization using, for example, toluene dried with sodium as a solvent. The ε-caprolactone can be purified, for example, by distillation under reduced pressure under a CaH2to N2atmosphere.

[0117] As the catalyst of the macromonomer synthesis step having lactic acid residues and caprolactone residues, a general germanium-based catalyst, a titanium-based catalyst, an antimony-based catalyst, a tin-based catalyst, or the like, which is a polymerization catalyst for a polyester, can be used. As a specific example of such a polymerization catalyst for a polyester, tin octoate, antimony trifluoride, zinc powder, dibutyl tin oxide, tin oxalate, or the like can be given. As a method of adding the catalyst to the reaction system, there is no particular limitation, and a method of adding in a state of being dispersed in the raw material at the time of raw material feeding or a method of adding in a state of being subjected to dispersion treatment at the start of the reduction is preferable. The amount of the catalyst used is 0.01 to 3 parts by weight, more preferably 0.05 to 1.5 parts by weight, based on the total amount of the monomers used, in terms of the metal atom.

[0118] The macromonomer having a lactic acid residue and a caprolactone residue can be obtained by charging lactide, caprolactone, and a catalyst into a reaction vessel equipped with a stirrer, and reacting them at 120 to 250°C under a stream of nitrogen. In the case where water is used as a co-initiator, it is preferable to perform a co-catalyst reaction at around 90°C before the polymerization reaction. As the reaction time, it is preferable to be 2 hours or more, and more preferably 4 hours or more, and in order to further increase the degree of polymerization, it is preferable to be longer, for example, 8 hours or more. However, if the reaction is performed for too long a time, there is a problem of coloring of the polymer, and therefore, the reaction time is preferably 3 to 30 hours.

[0119] Next, in the polymerization step, the ends of the gradient macromonomer having a lactic acid residue and a caprolactone residue are linked to each other by a condensation reaction, and thereby polymerization is performed. The reaction temperature of the condensation reaction is preferably 10 to 100°C, and more preferably 20 to 50°C. As the reaction time, it is preferable to be 1 day or more, and more preferably 2 days or more. However, if the reaction is performed for too long a time, there is a problem of coloring of the polymer, and therefore, the reaction time is preferably 2 to 4 days.

[0120] Preferably, the above-described polyester copolymer is a polyester copolymer having a structure in which two or more macromonomer units are linked, in the case where the speed of the one of monomer A and monomer B in which the initial polymerization speed is fast is set to V X , and the speed of the one of monomer A and monomer B in which the initial polymerization speed is slow is set to V Y , the above-described macromonomer unit satisfies 1.1 ≤ V X / V Y ≤ 40 with respect to the monomer A residue and the monomer B residue as the main structural unit. By making the above-described polyester copolymer having a structure in which two or more macromonomer units formed of the polyester copolymer in which the monomer A residue and the monomer B residue satisfy 1.1 ≤ V X / V Y ≤ 40 are linked, it is possible to make a gradient structure of the macromonomer unit, and as a result, the above-described polyester copolymer becomes a multi-gradient structure, and therefore, it is preferable.

[0121] Here, the speed V X of the one of monomer A and monomer B in which the initial polymerization speed is fast, and the speed V YThe following method is used. Monomer A and monomer B are mixed in equimolar amounts, a solvent and a catalyst are added as necessary, and the temperature and other conditions are adjusted so that the R value in the polyester copolymer to be finally synthesized described later is within an error of 10% to become the same R value, and the polymerization reaction is started. The remaining amounts of monomer A and monomer B are measured periodically from a sample in the polymerization. The remaining amounts are measured, for example, by chromatography, nuclear magnetic resonance (NMR) measurement. The amounts of monomers supplied to the polymerization reaction are obtained by subtracting the remaining amounts from the amounts of the respective monomers charged. If the amounts of the respective monomers supplied to the polymerization reaction are plotted against the sampling times, the initial slopes of the curves are V X and V Y .

[0122] In the case where the initial polymerization rate of monomer A is faster than that of monomer B, the probability that monomer A is bonded to the polymer terminal in the polymerization is high at the initial stage of the polymerization. On the other hand, at the late stage of the polymerization where monomer A is consumed and the concentration in the reaction solution decreases, the probability that monomer B is bonded to the polymer terminal in the polymerization becomes high. As a result, a gradient polymer in which the proportion of monomer A residues gradually decreases from one terminal can be obtained. The crystallinity of such a gradient polymer is low, and the increase in Young's modulus is also suppressed. In order to easily form such a gradient structure, V X / V Y is more preferably 1.3 or greater, and further preferably 1.5 or greater. On the other hand, if the difference between the polymerization rates of monomer A and monomer B is too large, a structure close to a block polymer in which monomer B is polymerized after only monomer A is polymerized is obtained, and sometimes the crystallinity of the obtained polymer becomes high to cause an increase in Young's modulus, and therefore, V X / V Y is more preferably 30 or less, further preferably 20 or less, and even more preferably 10 or less.

[0123] As such a preferred combination of monomer A and monomer B, propylene lactone and ε-caprolactone, glycolide and ε-caprolactone, glycolide and propylene lactone, propylene lactone and dioxepanone, ethylene oxalate and propylene lactone, propylene lactone and δ-valerolactone, glycolide and δ-valerolactone, and the like can be given.

[0124] The polymer composition of the present application contains a polyester copolymer and a biodegradable polymer, and the melting point of the biodegradable polymer is 100°C or higher. Note that the method of measuring the melting point is the same as that of measuring the polyester copolymer described above. However, in the production of a sample film, the solvent can be appropriately changed in the case where the biodegradable polymer is hardly soluble in chloroform, and a melt molding method such as a hot press method can also be used to produce a film.

[0125] In addition, the so-called biodegradability refers to a property of being decomposed in a living body, and the so-called biodegradable polymer refers to a polymer having such a property. As terms that can be used interchangeably with biodegradability, there are biocompatibility, biocompatibility, and the like. As the biodegradable polymer, there are, for example, polylactic acid, polyglycolic acid, polydioxanone, polypivalolactone, polyhydroxybutyric acid, polyhydroxyvaleric acid, polyhydroxyhexanoic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene succinate terephthalate, polytetramethylene succinate terephthalate, polybutylene succinate adipate terephthalate, polyvinyl alcohol, and the like. A copolymer of the above biodegradable polymer can also be used, but in the present application, only a copolymer having a melting point of 100°C or higher is limited. In addition, it can also be a mixture thereof or a mixture with a water-soluble polymer such as a polyalkylene glycol, and among them, a polymer selected from the group consisting of polylactic acid, polyglycolic acid, polybutylene succinate, polyhydroxybutyric acid, polyhydroxyhexanoic acid, poly(hydroxybutyric acid-hydroxyhexanoic acid) copolymer, and polydioxanone or a mixture thereof is preferable.

[0126] The so-called polyalkylene glycol is a polymer polymerized from one or more alkylene glycols. As the polyalkylene glycol, there are, for example, polyethylene glycol, propylene glycol, and the like, and copolymers thereof.

[0127] In the polymer composition of the present application, in order to control the tensile strength within an appropriate range, 0.1% by weight or more and less than 30% by weight of the biodegradable polymer is contained in 100% by weight of the total of the polyester copolymer and the biodegradable polymer. It is preferable to contain 0.1% by weight or more and less than 20% by weight of the biodegradable polymer, more preferable to contain 0.5% by weight to 15% by weight of the biodegradable polymer, and further preferable to contain 1.0% by weight to 10% by weight of the biodegradable polymer.

[0128] 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 further preferably 2 or more. In addition, if the content of the biodegradable polymer in the polymer composition is too much, the Young's modulus sometimes increases, 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, further preferably 2.5 or less, and most preferably 2 or less.

[0129] In addition, the polymer composition of the present application can contain a filler. As the filler, inorganic fillers such as talc, silica, clay, wollastonite, cristobalite, aluminum borate, mica, glass flake, carbon black, alumina, ferrite, graphite, carbon nanotube, 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, titanium oxide, and organic fillers such as aramid fiber, carbon fiber, glass fiber, gypsum fiber, and polyester fiber can be mentioned.

[0130] The content of the filler in the polymer composition is not particularly limited, and in order to control the biodegradability within an appropriate range, 0 to 3 parts by weight of the filler is preferably contained, more preferably 0 to 1 part by weight of the filler is contained, and further preferably 0 to 0.1 part by weight of the filler is contained, relative to 100 parts by weight of the total of the polyester copolymer and the biodegradable polymer. Note that the less the filler, the more preferable, and therefore, a mode in which the content of the filler is 0 parts by weight relative to 100 parts by weight of the total of the polyester copolymer and the biodegradable polymer, i.e., a mode in which no filler is contained, is particularly preferable.

[0131] The Young's modulus of the polymer composition of the present application is preferably 6.3 MPa or less, and the tensile strength is preferably 5 MPa or more. In addition, in order to control the biotic followability within an appropriate 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 further preferably 1.0 MPa or more. The upper limit of the Young's modulus is further preferably 5.0 MPa or less. Furthermore, for the same reason, the tensile strength of the polymer composition is more preferably 5 to 100 MPa. The lower limit of the tensile strength is further preferably 10 MPa or more, further 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 further preferably 80 MPa or less, particularly preferably 50 MPa or less.

[0132] Here, the Young's modulus and the tensile strength of the polymer composition can be measured according to the method prescribed in JIS K6251 (2017). Specifically, the polymer composition is dissolved in chloroform so that the concentration becomes 5% by weight, and the solution is transferred onto a Teflon-made flat plate and dried at normal pressure and room temperature for one day. A film obtained by drying under reduced pressure to a thickness of 0.1 mm is cut into a rectangular shape (30 mm x 5 mm), and a tensile test is performed under the following conditions using a small tabletop testing machine EZ-LX (manufactured by Shimadzu Corporation) to measure the Young's modulus and the tensile strength. Each is measured three times, and the average value is calculated, whereby the Young's modulus and the tensile strength of the polymer composition can be determined.

[0133] Initial length: 10 mm,

[0134] Stretching speed: 500 mm / min

[0135] Load sensor: 1kN

[0136] The polymer composition of the present invention may contain components other than the above-described polyester copolymer and biodegradable polymer, as long as it does not impair the effects of the present invention. In 100% by weight of the polymer composition of the present invention, it is preferable to contain a total of 50-100% by weight of polyester copolymer and biodegradable polymer, more preferably 70-100% by weight of polyester copolymer and biodegradable polymer, and even more preferably 90-100% by weight of polyester copolymer and biodegradable polymer.

[0137] The polymer compositions of the present invention are suitable for use as molded articles made from the polymer compositions of the present invention. Hereinafter, the molded articles of the present invention will be described.

[0138] The molded body of the present invention is made from the polymer composition of the present invention. In the present invention, the term "molded body" refers to an object obtained by molding the polymer composition of the present invention into various shapes according to a specific purpose using conventional methods. Examples of molded bodies include, for example, membranes (diaphragms, sheets), plates (plates), rods (rods), tubes (pipes), filaments (filaments), meshes (screens), bags, woven fabrics, or nonwoven fabrics.

[0139] The polymer composition of the present invention is suitable for processing and used as a filament. That is, the filament of the present invention is made from the polymer composition of the present invention. It should be noted that, in the present invention, the term filament, as described above, refers to a filamentous body, that is, a filamentous molded body. The filament is used in the form of a multifilament formed by twisting multiple filaments together to form a single filament, and in the form of a single filament used as a single filament.

[0140] Furthermore, the polymer composition of the present invention is suitable for use in medical molded articles. Medical molded articles are those described above that can be used for medical purposes. Examples of medical applications include sutures, artificial bones, artificial skin, wound dressing materials, carriers for DDS (Dual Injection Devices), microneedles, scaffold materials for tissue and organ regeneration, etc., but are not limited to these.

[0141] The polymer composition of the present application can be used as a stent. That is, the stent of the present application is made of the polymer composition of the present application. Here, the so-called stent is an implantable medical device which is radially expandable and is implantable to the inside of various body lumens or vessels (for example, vascular system, esophagus, gastrointestinal tract, large intestine and small intestine, bile duct, pancreatic duct, lung duct, urinary duct, and trachea, etc.). In the case where a body lumen or a vessel is narrowed, a stent is left in the narrowed portion in order to secure the lumen. Such a stent is an article which is left in a body lumen or a vessel for a long period of time, or an article which is removed from the body after maintaining the patency of the lumen for only a prescribed period of time.

[0142] In addition, the polymer composition of the present application is also preferably used for 3D printer applications.

[0143] Examples

[0144] Hereinafter, the present application will be described in detail by citing examples and comparative examples, but the present application is not limited thereto.

[0145] (Measurement Example 1: Measurement of molar fraction of each residue and R value by nuclear magnetic resonance (NMR))

[0146] The purified polyester copolymer was dissolved in deuterated chloroform, and the ratio of the lactic acid monomer residue and the caprolactone monomer residue in the polyester copolymer was calculated by 1 H-NMR measurement, respectively. In addition, by 1 H homonuclear decoupling, the adjacent monomer residues were separated into lactic acid residues or caprolactone residues for the methine group of the lactic acid residue (around 5.10 ppm) and the α-methylene group (around 2.35 ppm) and the ε-methylene group (around 4.10 ppm) of the caprolactone residue, and the peak areas of each were quantified. In the case where δ-valerolactone was used instead of ε-caprolactone, similarly, the adjacent monomer residues were separated into lactic acid residues or valerolactone residues for the methine group of the lactic acid residue (around 5.10 ppm) and the α-methylene group (around 2.35 ppm) and the δ-methylene group (around 4.10 ppm) of the valerolactone residue, and the peak areas of each were quantified.

[0147] From the ratio of the peak areas, [AB] was calculated and the R value was calculated. Here, [AB] is the molar fraction of the structure in which the lactic acid residue and the caprolactone residue or the valerolactone residue are adjacent in the copolymer. Specifically, it is the proportion (%) of the total number of A-B dyads and B-A dyads to the total number of A-A dyads, A-B dyads, B-A dyads, and B-B dyads. The results are shown in the table.

[0148] Apparatus name: JNM-ECZ400R (manufactured by JEOL Ltd.)

[0149] 1H homonuclear decoupling irradiation position: 1.66 ppm

[0150] Solvent: deuterated chloroform

[0151] Measurement temperature: room temperature.

[0152] (Measurement Example 2: Measurement of Weight Average Molecular Weight by Gel Permeation Chromatography (GPC))

[0153] Apparatus name: Prominence (manufactured by Shimadzu Corporation)

[0154] Mobile phase: chloroform (for HPLC) (manufactured by Wako Pure Chemical Industries, Ltd.)

[0155] Flow rate: 1 mL / min

[0156] Column: TSKgel GMHHR-M (φ 7.8 mm X 300 mm; manufactured by Tosoh Corporation)

[0157] Detector: UV (254 nm), RI

[0158] Column, detector temperature: 35°C

[0159] Standard substance: polystyrene

[0160] The purified polyester copolymer was dissolved in chloroform, and impurities and the like were removed by passing it through a 0.45-μm syringe filter (DISMIC-13HP; manufactured by ADVANTEC) and then the weight average molecular weight of the polyester copolymer was measured by GPC. The results are shown in the table.

[0161] (Measurement Example 3: Measurement of Crystallization Rate, Melting Point by Differential Scanning Calorimetry (DSC))

[0162] The polyester copolymer or biodegradable polymer was dissolved in chloroform so that the concentration became 5% by weight, and the solution was transferred to a Teflon-made flat dish and dried at room temperature under normal pressure for one day. It was dried under reduced pressure to obtain a film having a thickness of about 100 μm. The obtained film (about 10 mg) was collected in an alumina PAN, and the crystallization rate was calculated from the measurement results of the melting peak observed between the temperature conditions (D) to (E) by the DSC method under the following conditions using the following Formulas 1 and 2. In addition, the temperature at which the melting peak was observed was taken as the melting point, and in the case where no clear melting peak was observed, the polyester copolymer or biodegradable polymer was regarded as having no clear melting point.

[0163] In a case where a plurality of melting peaks is observed in a copolymer or the like, the sum of the product of the temperature at which each melting peak is observed and the weight fraction of the monomer residue that is the origin of the melting peak is taken as the melting point. That is, for example, in a case where a plurality of melting peaks is observed for a copolymer composed of monomer A residues and monomer B residues, the melting point of the copolymer can be found by {(temperature at which a melting peak from monomer A residues is observed) x (weight fraction of monomer A residues in the copolymer) + (temperature at which a melting peak from monomer B residues is observed) x (weight fraction of monomer B residues in the copolymer)}.

[0164] Apparatus name: EXSTAR 6000 (manufactured by Seiko Instruments Inc.)

[0165] Temperature conditions: (A) 25°C→(B) 250°C (10°C / min)→(C) 250°C (5 min)→(D) -70°C (10°C / min)→(E) 250°C (10°C / min)→(F) 250°C (5 min)→(G) 25°C (100°C / min)

[0166] Standard substance: alumina

[0167] Crystallization rate of monomer A = (heat of fusion per unit weight of monomer A residues in the polyester copolymer) / {(heat of fusion per unit weight of a homopolymer composed only of monomer A residues) x (weight fraction of monomer A residues in the polyester copolymer)} x 100... Equation 1

[0168] Crystallization rate of monomer B = (heat of fusion per unit weight of monomer B residues in the polyester copolymer) / {(heat of fusion per unit weight of a homopolymer composed only of monomer B residues) x (weight fraction of monomer B residues in the polyester copolymer)} x 100... Equation 2

[0169] Here, the heat of fusion per unit weight of the homopolymer is found as described below. A homopolymer composed only of monomer A residues and a homopolymer composed only of monomer B residues, which form the polyester copolymer, are each prepared, and each homopolymer is dissolved in chloroform so that the concentration becomes 5% by weight, and the solution is transferred to a Teflon flat plate and dried at normal pressure and room temperature for one day. It is subjected to reduced pressure drying to obtain a film. The obtained film is collected in alumina PAN, and the heat of fusion is read from the melting peak area of the graph obtained from the measurement results of the melting peaks observed between the temperature conditions (D) to (E) by the DSC method under the following conditions, using a differential scanning calorimeter.

[0170] Apparatus name: EXSTAR 6000 (manufactured by Seiko Instruments Inc.)

[0171] Temperature conditions: (A) 25°C → (B) 250°C (10°C / min) → (C) 250°C (5 min) → (D) -70°C (10°C / min) → (E) 250°C (10°C / min) → (F) 250°C (5 min) → (G) 25°C (100°C / min)

[0172] Standard substance: alumina.

[0173] (Measurement Example 4: Measurement of Young's modulus, tensile strength by tensile test)

[0174] The polymer composition was subjected to reduced pressure drying, dissolved in chloroform at a concentration of 5% by weight, and the solution was transferred to a Teflon flat plate, and dried at room temperature under normal pressure for one day. This was reduced pressure dried at 50°C for one day to obtain a film.

[0175] The obtained film (thickness about 0.1 mm) was cut into a rectangle (50 mm x 5 mm), and a tensile test was performed under the following conditions according to JIS K6251 (2017) to obtain Young's modulus and tensile strength. The results are shown in the table.

[0176] In addition, in the case where a mark line was drawn on the test piece, 2 mark lines were drawn on the test piece using an appropriate marker. When drawing the mark line, the test piece was in a state not stretched, and the mark line was accurately and clearly drawn at a right angle to the parallel portion of the test piece and at an equal distance from the center of the test piece.

[0177] Apparatus name: EZ-1k NLX (Shimadzu Access System)

[0178] Distance between mark lines before test: 10 mm

[0179] Distance between grips: 10 mm (position of gripping mark line)

[0180] Tensile speed: 500 mm / min

[0181] Load cell: 1 kN.

[0182] (Synthesis Example 1)

[0183] Purification of the polyester copolymer of 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 Corporation) were collected in a separable flask as monomers, and 0.45 g of hydroxy pivalic acid was collected as an initiator. These were reacted at 150°C for 9.5 hours under an argon atmosphere with 0.27 g of tin (II) octoate (manufactured by FUJIFILM Wako Pure Chemical Corporation) as a catalyst dissolved in 5.8 mL of toluene (super dehydrated) (manufactured by FUJIFILM Wako Pure Chemical Corporation) to obtain a crude copolymer.

[0184] The obtained crude copolymer was dissolved in 200 mL of chloroform, and was added dropwise to 3000 mL of hexane under stirring to obtain a precipitate. The precipitate was dried under reduced pressure at 50°C to obtain a macromonomer.

[0185] The macromonomer 50 g, 2.1 g of p-toluenesulfonic acid 4,4-dimethylaminopyridine (synthetic product), and 0.87 g of 4,4-dimethylaminopyridine (manufactured by FUJIFILM Wako Pure Chemical Corporation) were collected in a flask as a catalyst. These were dissolved in 200 mL of dichloromethane (dehydrated) (manufactured by FUJIFILM Wako Pure Chemical Corporation) under an argon atmosphere, 1.7 mL of diisopropyl carbodiimide (manufactured by FUJIFILM Wako Pure Chemical Corporation) was added as a condensing agent, and the condensation was carried out at room temperature overnight.

[0186] The obtained reaction mixture was diluted with 220 mL of chloroform, and 470 mL of 0.5 M hydrochloric acid was further added, and after stirring for 30 minutes, the water layer was removed by decantation. Then, the process of adding 470 mL of ion exchange water and stirring for 10 minutes, and removing the water layer by decantation was repeated until the pH of the removed water layer became 7. The residual organic layer was added dropwise to 2200 mL of methanol under stirring to obtain a precipitate. The precipitate was dried under reduced pressure at 50°C to obtain the purified polyester copolymer of Synthesis Example 1.

[0187] (Synthesis Example 2)

[0188] 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, and otherwise, the synthesis was carried out by the same method as in Synthesis Example 1 to obtain the purified polyester copolymer of Synthesis Example 2.

[0189] (Synthesis Example 3)

[0190] The amount of toluene was changed to 4.2 mL, and the amount of p-toluenesulfonic acid 4,4-dimethylaminopyridine The amount of the polyester copolymer was changed to 1.8 g, the amount of 4,4-dimethylaminopyridine was changed to 0.60 g, the amount of diisopropylcarbodiimide was changed to 1.5 mL, and otherwise, the synthesis was performed by the same method as in Synthesis Example 1 to obtain the purified polyester copolymer of Synthesis Example 3.

[0191] (Synthesis Example 1)

[0192] To a 50 mL screw tube, 987 mg of the polyester copolymer of Synthesis Example 1 and 13 mg of polylactic acid (manufactured by Nature 3D) were added, and dissolved in 20 mL of chloroform (manufactured by FUJIFILM Wako Pure Chemical Corporation) and dried at room temperature under normal pressure for one day. This was dried at 50°C under reduced pressure for one day to obtain the polymer composition of Example 1.

[0193] (Synthesis Example 2)

[0194] The amount of the polyester copolymer was changed to 979 mg, the amount of polylactic acid was changed to 21 mg, and otherwise, the operation was performed by the same method as in Example 1 to obtain the polymer composition of Example 2.

[0195] (Synthesis Example 3)

[0196] The amount of the polyester copolymer was changed to 963 mg, the amount of polylactic acid was changed to 37 mg, and otherwise, the operation was performed by the same method as in Example 1 to obtain the polymer composition of Example 3.

[0197] (Synthesis Example 4)

[0198] The amount of the polyester copolymer was changed to 877 mg, the amount of polylactic acid was changed to 123 mg, and otherwise, the operation was performed by the same method as in Example 1 to obtain the polymer composition of Example 4.

[0199] (Synthesis Example 5)

[0200] Polylactic acid (manufactured by Nature 3D) was changed to polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.), and otherwise, the operation was performed by the same method as in Example 1 to obtain the polymer composition of Example 5.

[0201] (Synthesis Example 6)

[0202] The amount of the polyester copolymer was changed to 979 mg, polylactic acid (manufactured by Nature 3D) was changed to polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.), the amount of polylactic acid was changed to 21 mg, and otherwise, the operation was performed by the same method as in Example 1 to obtain the polymer composition of Example 6.

[0203] (Synthesis Example 7)

[0204] The amount of the polyester copolymer was changed to 959 mg, the polylactic acid (manufactured by Nature 3D) was changed to polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.), the amount of the polylactic acid was changed to 42 mg, and otherwise, the same method as in Example 1 was performed to obtain the polymer composition of Example 7.

[0205] (Example 8)

[0206] The amount of the polyester copolymer was changed to 921 mg, the polylactic acid (manufactured by Nature 3D) was changed to polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.), the amount of the polylactic acid was changed to 79 mg, and otherwise, the same method as in Example 1 was performed to obtain the polymer composition of Example 8.

[0207] (Comparative Example 1)

[0208] Into a 50 mL screw tube, 1000 mg of the polyester copolymer of Synthesis Example 1 was added and dissolved in chloroform (manufactured by FUJIFILM Wako Pure Chemical Corporation) 20 mL, and dried at room temperature under normal pressure for one day. This was dried under reduced pressure at 50°C for one day to obtain the polymer composition of Comparative Example 1.

[0209] (Comparative Example 2)

[0210] The amount of the polyester copolymer was changed to 594 mg, the amount of the polylactic acid was changed to 406 mg, and otherwise, the same method as in Example 1 was performed to obtain the polymer composition of Comparative Example 2.

[0211] (Comparative Example 3)

[0212] The amount of the polyester copolymer was changed to 498 mg, the amount of the polylactic acid was changed to 502 mg, and otherwise, the same method as in Example 1 was performed to obtain the polymer composition of Comparative Example 3.

[0213] (Comparative Example 4)

[0214] The amount of the polyester copolymer was changed to 700 mg, the polylactic acid (manufactured by Nature 3D) was changed to polylactic acid (manufactured by Wako Pure Chemical Industries, Ltd.), the amount of the polylactic acid was changed to 300 mg, and otherwise, the same method as in Example 1 was performed to obtain the polymer composition of Comparative Example 4.

[0215] (Comparative Example 5)

[0216] The amount of the polyester copolymer was changed to 980 mg, and instead of the polylactic acid (manufactured by Nature 3D) 13 mg, polycaprolactone (manufactured by Sigma-Aldrich) 20 mg was changed, and otherwise, the same method as in Example 1 was performed to obtain the polymer composition of Comparative Example 5.

[0217] (Comparative Example 6)

[0218] The amount of the polyester copolymer was changed to 899 mg, and instead of polylactic acid (manufactured by Nature 3D) 13 mg, polycaprolactone (manufactured by Sigma Aldrich) 101 mg was changed, and otherwise, the same method as in Example 1 was used to perform the operation to obtain the polymer composition of Comparative Example 6.

[0219] (Comparative Example 7)

[0220] The amount of the polyester copolymer was changed to 500 mg, and instead of polylactic acid (manufactured by Nature 3D) 13 mg, polycaprolactone (manufactured by Sigma Aldrich) 500 mg was changed, and otherwise, the same method as in Example 1 was used to perform the operation to obtain the polymer composition of Comparative Example 7.

[0221] (Example 9)

[0222] The amount of the polyester copolymer was changed to 960 mg, and polylactic acid (manufactured by Nature 3D) was changed to polybutylene succinate (manufactured by Nature 3D), and the amount of polybutylene succinate was changed to 40 mg, and otherwise, the same method as in Example 1 was used to perform the operation to obtain the polymer composition of Example 9.

[0223] (Example 10)

[0224] The amount of the polyester copolymer was changed to 813 mg, and the amount of polylactic acid was changed to 187 mg, and otherwise, the same method as in Example 1 was used to perform the operation to obtain the polymer composition of Example 10.

[0225] (Example 11)

[0226] The polyester copolymer of Synthetic Example 1 was changed to the polyester copolymer of Synthetic Example 2, the amount of the polyester copolymer was changed to 961 mg, and the amount of polylactic acid was changed to 40 mg, and otherwise, the same method as in Example 1 was used to perform the operation to obtain the polymer composition of Example 11.

[0227] (Example 12)

[0228] The polyester copolymer of Synthetic Example 1 was changed to the polyester copolymer of Synthetic Example 2, the amount of the polyester copolymer was changed to 900 mg, and the amount of polylactic acid was changed to 100 mg, and otherwise, the same method as in Example 1 was used to perform the operation to obtain the polymer composition of Example 12.

[0229] (Example 13)

[0230] 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 the polylactic acid was changed to 120 mg, and otherwise, the same method as in Example 1 was used to perform the operation to obtain the polymer composition of Example 14.

[0231] (Example 14)

[0232] 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 the polylactic acid was changed to 120 mg, and otherwise, the same method as in Example 1 was used to perform the operation to obtain the polymer composition of Example 14.

[0233] (Comparative Example 8)

[0234] The amount of the polyester copolymer was changed to 700 mg, and the polylactic acid (manufactured by Nature 3D) was changed to polybutylene succinate (manufactured by Nature 3D), and the amount of the polybutylene succinate was changed to 300 mg, and otherwise, the same method as in Example 1 was used to perform the operation to obtain the polymer composition of Comparative Example 8.

[0235] (Comparative Example 9)

[0236] The polyester copolymer of Synthesis Example 1 was changed to the polyester copolymer of Synthesis Example 2, and otherwise, the same method as in Comparative Example 1 was used to perform the operation to obtain the polymer composition of Comparative Example 9.

[0237] (Comparative Example 10)

[0238] The polyester copolymer of Synthesis Example 1 was changed to the polyester copolymer of Synthesis Example 3, and otherwise, the same method as in Comparative Example 1 was used to perform the operation to obtain the polymer composition of Comparative Example 10.

[0239] For the polymer compositions of Examples 1 to 14 and Comparative Examples 1 to 10, the measurements described in Measurement Examples 1 to 4 were performed. The results are shown in the table. However, Comparative Example 8 could not make a film, and thus it was not possible to perform the measurements.

[0240] The evaluation of Measurement Example 4 was performed.

[0241] [Table 1]

[0242]

[0243] [Table 2]

[0244]

[0245] Note that the monomer A residue ratio in the table indicates the molar ratio of monomer A residues relative to the total moles of monomer A residues and monomer B residues, which is 100%.

[0246] Mw in the table indicates the weight average molecular weight.

[0247] Industrial applicability

[0248] As specific uses of the polymer composition of the present application, use in nonwoven fabrics and the like among fibers, disposable toiletries as containers, cosmetics, packaging films as films, agricultural multilayer films, tapes, and the like can be considered. Furthermore, as medical uses, suture threads, artificial bones, artificial skins, wound covering materials, carriers for DDS, micro-needles, scaffolding materials for the regeneration of tissues and organs, and the like can be considered. Furthermore, use in other toners, binders for thermal transfer inks, 3D printer uses, and the like can be considered, but are not limited thereto.

Claims

1. A polymer composition which is a polymer composition containing a polyester copolymer and a biodegradable polymer, the polyester copolymer having 2 ester bond-forming monomer residues as main constitutional units, in the case where the 2 ester bond-forming monomers are respectively designated as "monomer A" and "monomer B", the polyester copolymer satisfies the following (1) to (3), the biodegradable polymer has a melting point of 100°C or higher, in 100% by weight of the total of the polyester copolymer and the biodegradable polymer, the biodegradable polymer is contained in an amount of 0.1% by weight or more and less than 30% by weight, (1) the R value is 0.45 or more and 0.99 or less, R = [AB] / (2[A][B]) x 100 [A]: molar fraction of monomer A residue in the polyester copolymer, [B]: molar fraction of monomer B residue in the polyester copolymer, [AB]: molar fraction of structure in which monomer A residue and monomer B residue are adjacent, i.e., A-B and B-A, in the polyester copolymer, the unit of the above molar fraction being %; (2) the crystallization rate of monomer A residue and the crystallization rate of monomer B residue are less than 14%; (3) the melting point is less than 100°C or no definite melting point is present, the monomer A is a compound selected from the group consisting of lactic acid, glycolic acid, lactide and glycolide, the monomer B is a compound selected from the group consisting of hydroxyvaleric acid, hydroxyhexanoic acid, valerolactone and caprolactone, the biodegradable polymer is a polymer selected from the group consisting of polylactic acid, polyglycolic acid, polybutylene succinate, polyhydroxybutyric acid ester, polyhydroxyhexanoic acid ester, poly(hydroxybutyric acid ester hydroxyhexanoic acid ester) copolymer and polydioxanone, or a mixture thereof, the weight average molecular weight of the polyester copolymer is 60,000 or more, the Young's modulus of the polymer composition is 6.3 MPa or less and the tensile strength is 5 MPa or more.

2. The polymer composition according to claim 1, containing a filler in an amount of 0 to 3 parts by weight with respect to 100 parts by weight of the total of the polyester copolymer and the biodegradable polymer.

3. The polymer composition according to claim 1 or 2, the polyester copolymer being a polyester copolymer having a structure in which 2 or more macromonomer units are linked, In the case where the speed of the one of the monomer A and the monomer B in which the initial polymerization speed is fast is set to V X , and the speed of the one of the monomer A and the monomer B in which the initial polymerization speed is slow is set to V Y , the macromonomer unit has a monomer A residue and a monomer B residue as a main structural unit, which satisfies 1.1 ≤ V X / V Y ≤ 40.

4. The polymer composition according to claim 1 or 2, containing the polyester copolymer and the biodegradable polymer in a total amount of 50 to 100% by weight in 100% by weight of the polymer composition.

5. A molded body which is made of the polymer composition according to any one of claims 1 to 4.

6. A filament which is made of the polymer composition according to any one of claims 1 to 4.

7. A stent which is made of the polymer composition according to any one of claims 1 to 4.

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