Filament for 3D printer and method for manufacturing the same

Abstract

To provide a filament for 3D printers that has both high printability and transparency.SOLUTION: The present invention provides a filament for a 3D printer, which comprises a polyester copolymer, does not comprise a water-soluble polymer or a biodegradable polymer different from the polyester copolymer, and has a melting enthalpy of greater than 0.0 J / g and not greater than 10.0 J / g.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a filament for a 3D printer and a method for producing the same. [Background technology]

[0002] Fused deposition modeling 3D printers, which create shapes by feeding a filament made of thermoplastic resin through a feeder and melting it and extruding it from a nozzle, are becoming increasingly popular and are widely used not only for personal use but also for industrial purposes such as manufacturing parts.

[0003] In recent years, 3D printers have also been deployed for medical applications, drawing attention to personalized medicine, where custom-made medical devices are created using 3D printers to fit the unique bone and organ shapes of each patient and then implanted into the body. When creating medical devices to be implanted into the body using a 3D printer, the materials are often required to be biodegradable, meaning they must break down and be excreted from the body after their role has been completed. Furthermore, in the case of medical devices that target soft tissues, flexibility is also required.

[0004] As such materials, Patent Document 1 discloses a polyester copolymer whose main structural units are two types of ester bond-forming monomer residues, and Patent Document 2 discloses a filament for 3D printers that contains an amorphous biodegradable polyester and a water-soluble polymer or biodegradable polymer that is different from the biodegradable polyester. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 035357 [Patent Document 2] International Publication No. 2023 / 058572 Summary of the Invention [Problem to be solved by the invention]

[0006] When filaments are produced using the polymer described in Patent Document 1, they are often sticky, causing the filaments to adhere to each other or to the inner wall of the guide tube that supports the feed, resulting in poor printability. Furthermore, the diameter of the obtained filaments is non-uniform, and poor printability is also an issue from the perspective of diameter uniformity.

[0007] On the other hand, Patent Document 2 discloses a method of adding a water-soluble polymer or a biodegradable polymer other than an amorphous biodegradable polyester (i.e., a polyester copolymer) as a method of reducing the stickiness of a polymer. However, although the filament described in Patent Document 2 has excellent diameter uniformity and printability, it has the problem of insufficient transparency. Medical devices made using filaments with insufficient transparency make it difficult to visually identify the affected area, so it is desirable for filaments used in medical devices to have high transparency.

[0008] Therefore, an object of the present invention is to provide a filament for 3D printers that combines high printability and transparency. [Means for solving the problem]

[0009] The present invention is intended to solve the above problems as follows. [1] A filament for a 3D printer that contains a polyester copolymer, does not contain a water-soluble polymer or a biodegradable polymer different from the polyester copolymer, and has a melting enthalpy of greater than 0.0 J / g and less than or equal to 10.0 J / g. [2] The filament according to [1], which consists solely of the polyester copolymer. [3] The polyester copolymer is a polyester copolymer having two types of ester bond-forming monomer residues as main constituent units, and when the two types of ester bond-forming monomers are referred to as "monomer A" and "monomer B," respectively, the polyester copolymer satisfies the following (1) and (2): [1] a filament according to [1] or [2]. (1) The R value represented by the following formula is 0.45 or more and 0.99 or less. R value = [AB] / (2[A][B]) x 100 [A]: Molar fraction of monomer A residues in the polyester copolymer [B]: Molar fraction of monomer B residues in the polyester copolymer [AB]: Molar fraction of structures (AB and BA) in which monomer A residue and monomer B residue are adjacent to each other in the polyester copolymer (2) The crystallinity of at least one of the monomer A residue and the monomer B residue is less than 14%. [4] The filament according to [1] or [2], wherein the two types of ester bond-forming monomers are two types selected from the group consisting of hydroxycarboxylic acids, lactones, and lactides. [5] A method for producing a filament according to [1] or [2], comprising an extrusion molding step of extruding pellets of a composition containing a polyester copolymer and not containing a water-soluble polymer or a biodegradable polymer different from the polyester copolymer at a temperature of 90°C or higher and 150°C or lower. [6] A molded article obtained by molding the filament according to [1] or [2]. [7] A method for manufacturing a molded body using a 3D printer, comprising: a melting step of melting the filament described in [1] or [2] using a temperature-controllable nozzle; a layer forming step of forming layers by ejecting the molten filament while moving the head of the 3D printer horizontally; and a molded body forming step of stacking the molten filament to form a molded body by repeating the layer forming step. [Effects of the Invention]

[0010] The present invention makes it possible to obtain a filament for 3D printers that combines high printability and transparency, and to produce molded articles suitable for medical applications. DETAILED DESCRIPTION OF THE INVENTION

[0011] The filament for 3D printers of the present invention contains a polyester copolymer, does not contain a water-soluble polymer or a biodegradable polymer different from the polyester copolymer, and has a melting enthalpy of greater than 0.0 J / g and not greater than 10.0 J / g.

[0012] <Polyester copolymer> The polyester copolymer is preferably a copolymer having two types of ester bond-forming monomer residues as main structural units. In this specification, the two types of ester bond-forming monomers may be referred to as "monomer A" and "monomer B," respectively.

[0013] The term "ester bond-forming monomer" refers to a monomer that, after polymerization, produces a polymer in which the monomer units are linked by ester bonds, i.e., a polyester.

[0014] 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 carboxyl group of a hydroxycarboxylic acid, and lactides, which are cyclic compounds formed by dehydration condensation of the hydroxy group and carboxyl group of two molecules of hydroxycarboxylic acid.

[0015] The hydroxycarboxylic acid is preferably an aliphatic hydroxycarboxylic acid, such as lactic acid, glycolic acid, hydroxybutyric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, hydroxynonanoic acid, hydroxydecanoic acid, hydroxyundecanoic acid, hydroxydodecanoic acid, and (2-hydroxyethoxy)acetic acid, with lactic acid, glycolic acid, hydroxypentanoic acid, or hydroxycaproic acid being preferred.

[0016] Although L-lactic acid, D-lactic acid, and mixtures thereof can be used as 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.

[0017] Examples of lactones that can be used include caprolactone, dioxepanone, ethylene oxalate, dioxanone, 1,4-dioxane-2,3-dione, β-propiolactone, δ-valerolactone, β-propiolactone, β-butyrolactone, γ-butyrolactone, and pivalolactone.

[0018] 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, or tetramethyl glycolide can be used.

[0019] As the ester bond-forming monomer, derivatives of the above-exemplified monomers can also be used.

[0020] 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, when lactic acid (CHCH(OH)COOH) and caprolactone (ε-caprolactone: formula (I) below) are polymerized to form a copolymer of lactic acid and caprolactone, the unit represented by formula (R1) below is a lactic acid monomer residue, and the unit represented by formula (R2) below is a caprolactone monomer residue.

[0021] [ka]

[0022] [ka]

[0023] [ka]

[0024] 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, when dilactide (L-(-)-lactide: Formula (II) below) is polymerized with caprolactone, the resulting copolymer has a chemical structure in which the structure shown in Formula (R1) above is repeated twice as the dilactide residue.

[0025] [ka]

[0026] In this case, one of the lactic acid units is considered to be a "monomer residue," and two "monomer residues," i.e., two lactic acid residues, are considered to have been formed from dilactide.

[0027] "Two types of monomer residues are the "main structural units"" means that the sum of the number of the two types of monomer residues is 50 mol % or more of the total number of residues in the entire polymer, including other monomer residues, and the number of each of the two types of monomer residues is 20 mol % or more of the total number of residues in the entire polymer. For example, "monomer A residues and monomer B residues are the main structural units" means that the sum of the number of monomer A residues and monomer B residues is 50 mol % or more of the total number of residues in the entire polymer, the number of monomer A residues is 20 mol % or more of the total number of residues in the entire polymer, and the number of monomer B residues is 20 mol % or more of the total number of residues in the entire polymer.

[0028] Here, the molar fractions of the monomer A residue, the monomer B residue, and other monomer residues can be determined by nuclear magnetic resonance (NMR) measurement from the area value of the signal derived from each residue. For example, when the monomer A residue is a lactic acid residue and the monomer B residue is a caprolactone residue, they can be measured by the method described in Measurement Method 2 below. When the monomer is lactide, the area value of the signal derived from the lactic acid residue is considered to be the area value of the signal derived from the lactide residue, and the molar fraction of the lactic acid residue is considered to be the molar fraction of the lactide residue.

[0029] The sum of the monomer A residues and the monomer B residues, as defined above, is 50 mol % or more, preferably 75 mol % or more, and more preferably 90 mol % or more of the entire polymer including other monomer residues. Also, as defined above, the sum of the monomer A residues and the monomer B residues is 20 mol % or more, preferably 30 mol % or more, and more preferably 40 mol % or more. A particularly preferred embodiment is a polymer in which the sum of the monomer A residues and the monomer B residues is 100% of the entire polymer, i.e., a polymer consisting only of monomer A and monomer B.

[0030] In the polyester copolymer, the molar ratio of monomer A residues to monomer B residues is preferably 7 / 3 to 3 / 7, more preferably 6 / 4 to 4 / 6, since the presence of an excess of one monomer approaches homopolymer-like properties.

[0031] As long as the effects of the present invention are not impaired, other monomers that can be copolymerized with the two ester bond-forming monomers that constitute the main structural units can also be copolymerized. Such monomers can be other than the above-mentioned ester bond-forming monomers.

[0032] 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, dialcohols, dicarboxylic acids, amino acids, diamines, diisocyanates, and diepoxides other than the two ester bond-forming monomers that constitute the main structural units.

[0033] 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.

[0034] The polyester copolymer is preferably biodegradable or bioabsorbable. Those skilled in the art will be able to synthesize a copolymer that exhibits appropriate biodegradability or bioabsorbability depending on the application by appropriately combining the above-exemplified monomers or adjusting the ratio of the monomers within the range specified in the present invention.

[0035] When the two aforementioned ester bond-forming monomers are copolymerized in equimolar amounts, the monomer with a relatively high initial polymerization rate is designated "monomer A" and the monomer with a low initial polymerization rate is designated "monomer B." The initial polymerization rates when these two monomers are copolymerized in equimolar amounts are V A , V B When V is A / V B It is preferable that the value satisfies ≦40.

[0036] where V A , V Bcan be determined by the following method. Equimolar amounts of monomer A and monomer B are mixed, and a solvent and catalyst are added as necessary. The polymerization reaction is initiated by adjusting the temperature and other conditions so that the R value, described below, of the polyester copolymer finally synthesized or to be synthesized is within an error of 10% of the preferred range of R values, described below. 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 determined by subtracting the remaining amount from the charged amount. When the amount of monomer used in the polymerization reaction is plotted against the sampling time, if the initial slope of the curve is V A , V B is.

[0037] When such monomer A and monomer B are reacted, 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 A / V B 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 monomer A and monomer B is too large, a structure similar to a block polymer will be formed in which only monomer A is polymerized and then monomer B is polymerized, which may result in high crystallinity and an increase in Young's modulus. A / V B is more preferably 30 or less, even more preferably 20 or less, and most preferably 10 or less.

[0038] 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, and glycolide and δ-valerolactone.

[0039] In the present invention, a particularly preferred embodiment is that the monomer A residue is a lactic acid residue and the monomer B residue is a caprolactone residue.

[0040] (1) R-value The polyester copolymer preferably has an R value represented by the following formula of 0.45 or more and 0.99 or less, where the two types of ester bond-forming monomers mentioned above are "monomer A" and "monomer B", respectively. R value = [AB] / (2[A][B]) x 100 [A]: Molar fraction of monomer A residues in the polyester copolymer [B]: Molar fraction of monomer B residues in the polyester copolymer [AB]: Molar fraction of structures (AB and BA) in which monomer A residue and monomer B residue are adjacent to each other in the polyester copolymer

[0041] 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, i.e., monomer A residue and monomer B residue. For example, a random copolymer in which the monomer arrangement is completely random has an R value of 1. In addition, the R value of a block copolymer is 0 to 0.44.

[0042] The R value can be determined by quantifying the ratio of adjacent monomer combinations (AA, BB, AB, BA) using nuclear magnetic resonance (NMR) measurement, for example, by the method described in Measurement Method 2 below. If the R value is less than 0.45, the crystallinity is high, and the molded copolymer article becomes hard and the Young's modulus increases. On the other hand, if the R value exceeds 0.99, the molded copolymer article becomes too soft and sticky, resulting in poor handleability. Therefore, it is more preferable that the R value of the polyester copolymer is 0.50 or more and 0.80 or less.

[0043] (2) Crystallization rate It is known that the crystallinity of a polymer has a significant effect on its mechanical strength. Generally, low-crystalline polymers exhibit a low Young's modulus, so low crystallinity is desirable for flexibility. The crystallinity of a polymer can be determined from the heat of fusion using differential scanning calorimetry (DSC) measurements.

[0044] In the polyester copolymer, the crystallinity of at least one of the monomer A residue and the monomer B residue is preferably less than 14%. If the crystallinity is less than 14%, an increase in Young's modulus is suppressed, and the polyester copolymer can be used for medical materials and elastomers. The crystallinity of at least one of the monomer A residue and / or the monomer B residue is more preferably 10% or less, and even more preferably 5% or less.

[0045] The crystallization 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 a certain monomer residue and the weight fraction of that monomer residue in the polyester copolymer. In other words, the crystallization ratio of a monomer A residue is the ratio of the heat of fusion per unit weight of a 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 the monomer A residue in the polyester copolymer. The crystallization ratios of the monomer A residue and the monomer B residue indicate the proportions of the monomer A residue and the monomer B residue, respectively, that form a crystalline structure in the polyester copolymer. When the monomer is lactide, the lactic acid residue is considered to be the lactide residue.

[0046] In particular, 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 is preferably less than 14%, more preferably 10% or less. The crystallinity can be determined, for example, by the method described in Measurement Method 4 below.

[0047] The weight-average molecular weight of the polyester copolymer of the present invention is preferably 60,000 or more to obtain the effect of improving tensile strength due to entanglement of polymer chains. However, if the weight-average molecular weight of the polyester copolymer is too low, the melt viscosity will be low, and if the weight-average molecular weight is too high, the melt viscosity will be high, and in either case, extrusion molding will be difficult. Therefore, from the viewpoint of handling during extrusion molding, the weight-average molecular weight of the polyester copolymer is more preferably 100,000 or more, even more preferably 150,000 or more, and most preferably 200,000 or more. Furthermore, the weight-average molecular weight of the polyester copolymer is preferably 500,000 or less, more preferably 400,000 or less, and even more preferably 300,000 or less.

[0048] The weight average molecular weight can be determined by gel permeation chromatography (GPC), for example, by the method described in Measurement Method 1 below.

[0049] <Method of manufacturing polyester copolymer> For example, polyester copolymers can be prepared by a macromer synthesis step in which two ester bond-forming monomers, Monomer A and Monomer B, are blended and polymerized so that the sum of Monomer A residues and Monomer B residues is 50 mol % or more of the total residues and Monomer A residues and Monomer B residues are each 20 mol % or more of the total residues at the completion of polymerization; and a multiplication step of linking the macromers obtained in the macromer synthesis step to each other or by adding the monomer A and the monomer B to the macromer solution obtained in the macromer synthesis step; The film can be produced by a production method having the following steps.

[0050] [Macromer synthesis process] In the macromer synthesis step, monomer A and monomer B are polymerized by mixing them together so that, theoretically, at the completion of polymerization, the sum of monomer A residues and monomer B residues 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.

[0051] As the ester bond-forming monomer, the same ones as those described above can be used, and the preferred combinations etc. are also as described above.

[0052] 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 the monomers during polymerization. That is, if one of the two monomers is bound to the other with equal probability during polymerization, a random 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 composition of monomer residues along its molecular chain from the initiation end to the termination end of polymerization.

[0053] If monomer A has a higher initial polymerization rate than monomer B, then when monomer A and monomer B are copolymerized in the macromer synthesis step, monomer A is likely to bond after monomer A. As a result, the synthesized macromer forms a gradient structure in which the proportion of monomer A units gradually decreases from the polymerization initiation end to the polymerization termination end. In other words, 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. Such macromers are sometimes referred to herein as "gradient macromers."

[0054] 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 and living polymerization.

[0055] The macromer obtained in the macromer synthesis step preferably satisfies the R value range described in (1) above in order to facilitate the final production of a polyester copolymer that satisfies the R value range described in (1) above. That is, the macromer preferably has an R value represented by the following formula of 0.45 or more and 0.99 or less, more preferably 0.50 or more and 0.80 or less. R value = [AB] / (2[A][B]) x 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 the structure (AB and BA) in which a monomer A residue and a monomer B residue are adjacent to each other in the macromer

[0056] Similarly, the macromer obtained in the macromer synthesis step preferably satisfies the range of crystallinity of the monomer residues described in (2) above, in order to facilitate the final production of a polyester copolymer in which the range of crystallinity of the monomer A residue or the monomer B residue described in (2) above is satisfied. That is, the macromer preferably has a crystallinity of at least one of the monomer A residue or the monomer B residue of less than 14%, more preferably 10% or less, even more preferably 5% or less, and most preferably 1% or less.

[0057] 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, and in order to suppress crystallinity and maintain flexibility, it is preferably 150,000 or less, more preferably 100,000 or less.

[0058] [Mulching process] In the multi-merization step, the macromers obtained in the macromer synthesis step are linked together, or the macromer solution obtained in the macromer synthesis step is multi-merized by adding monomer A and monomer B to the macromer solution. 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-merization" means that, by either of these methods, a structure is formed in which multiple repeating molecular chains have a gradient structure in which monomer A residues and monomer B residues have a composition gradient in the backbone.

[0059] The number of multi-linked macromer units may 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 as a result, 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.

[0060] 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.

[0061] The polyester copolymer of the present invention may be a linear polymer in which macromer units are linearly linked, or a branched polymer in which macromer units are branched and linked.

[0062] 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.

[0063] When the gradient macromer has a hydroxyl group and a carboxyl group at each end, 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.

[0064] Furthermore, when the polymerization reaction has a living property, i.e., when 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 is completed.

[0065] 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 a branched polyester copolymer in which the linker is the branch point.

[0066] The polyester copolymer obtained by the above-described production method is a copolymer having a structure in which two or more macromer units, in which monomer A residues and monomer B residues have a composition gradient in the backbone, are linked together, and this is a preferred embodiment of the polyester copolymer. In this specification, for convenience, such a structure may be referred to as a "multi-gradient" and a copolymer having a multi-gradient structure may be referred to as a "multi-gradient copolymer." A multi-gradient copolymer preferably has a structure in which two or more macromer units, in which monomer A residues and the above-described monomer B residues have a gradient structure in which a composition gradient is formed in the backbone, are linked together, and more preferably has a structure in which three or more macromer units are linked together.

[0067] As mentioned above, a particularly preferred embodiment 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.

[0068] First, in the macromer synthesis process, dilactide and ε-caprolactone are polymerized in the presence of a catalyst. The dilactide and ε-caprolactone monomers are preferably purified to remove impurities before use. For example, dilactide can be purified by recrystallization from toluene dried with sodium hydroxide. For example, ε-caprolactone can be purified by vacuum distillation from CaH2 under an N2 atmosphere.

[0069] The reactivity of dilactide and ε-caprolactone is significantly different, as reported in the literature (DW Grijpma and AJ Pennings, Polymer Bulletin, Vol. 25, 335-341), and the initial polymerization rate of dilactide monomer is higher than that of ε-caprolactone. A The reaction rate (%) was 3.6% / h, and the V B is 0.88% / h, and V A / V B is 4.1. Therefore, the macromer obtained by copolymerizing dilactide and ε-caprolactone is a gradient macromer.

[0070] As a catalyst for the synthesis of a macromer having lactic acid residues and caprolactone residues, conventional polyester polymerization catalysts such as germanium-, titanium-, antimony-, 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 dispersed state in the raw materials when they are charged, or in a dispersed state when the pressure reduction begins. The amount of catalyst used is preferably 0.01 to 3 wt. % in terms of metal atoms, and more preferably 0.05 to 1.5 wt. % of the total amount of monomers used.

[0071] 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 water is used 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 for the co-catalyst reaction is 2 hours or more, preferably 4 hours or more, and even longer, for example, 8 hours or more, is more preferable to increase the degree of polymerization. However, since carrying out the reaction for a long period of time can cause problems with coloration of the polymer, the reaction time for the co-catalyst reaction is preferably 12 hours or less.

[0072] 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 a multi-polymer. The reaction temperature for the condensation reaction is preferably 10 to 100°C, more preferably 20 to 50°C. The reaction time for the condensation reaction is preferably one day or more, and more preferably two days or more. However, since carrying out the reaction for a long period of time can cause problems with coloration of the polymer, the reaction time for the condensation reaction is preferably four days or less.

[0073] <3D printer filament> The filament for 3D printers of the present invention does not contain a water-soluble polymer or a biodegradable polymer different from the polyester copolymer, and preferably consists only of the polyester copolymer.

[0074] Examples of water-soluble polymers other than the polyester copolymers include polyethylene glycol (PEG), polypropylene glycol, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyvinylacetamide, polymaleic acid, polysulfonic acid, polyvinyl alcohol (PVA), polyethyleneimine, carboxymethylcellulose, alginic acid, polyphosphate, starch, agar, gelatin, pullulan, dextrin, and xanthan gum, as well as their salts, copolymers, and copolymer salts. Whether a target polymer is water-soluble can be determined by adding the polymer to water, stirring for a certain period of time, and visually confirming that the polymer has dissolved. For example, if 1 g of the polymer is added to 100 mL of water heated to 37°C and stirred for 3 hours, and the polymer is visually confirmed to have dissolved, the target polymer is a water-soluble polymer.

[0075] Biodegradability refers to the property of being broken down in a living organism or in the environment. Whether a polymer is biodegradable can be confirmed, for example, by measuring the degree of biodegradation based on the amount of oxygen consumed when the polymer is decomposed in activated sludge, or by measuring the change in molecular weight (molecular weight reduction rate) of the polymer when immersed in an aqueous solution. The degree of biodegradation can be measured in accordance with the method specified in JIS K6950 (2000). The molecular weight reduction rate can be measured, for example, according to Measurement Method 3 described below. A polymer with a biodegradability or molecular weight reduction rate of 60% or more is considered a biodegradable polymer. The biodegradability of filaments can also be determined in the same way as for polymers.

[0076] Terms that can be used interchangeably with biodegradability include bioabsorbability and biocompatibility, but these terms often refer primarily to the property of being broken down in the body.

[0077] Examples of biodegradable polymers other than the above polyester copolymers include polylactic acid (hereinafter referred to as "PLA"), polyglycolic acid, polycaprolactone, polydioxanone, polyvalerolactone, polyhydroxybutyrate, polyhydroxyvalerate, polyhydroxyhexanoate, polybutylene succinate, polybutylene succinate adipate, polybutylene succinate carbonate, polybutylene adipate terephthalate, polytetramethylene adipate terephthalate, polyethylene terephthalate succinate, PVA, pullulan, etc. As mentioned above, PVA and pullulan are also water-soluble polymers, and therefore are polymers that are both water-soluble and biodegradable.

[0078] The fusion enthalpy of the filament can be measured by the method described in Measurement Method 4 below. If the fusion enthalpy of the filament is 0.0 J / g, the filament will become sticky, and if the fusion enthalpy of the filament is too high, transparency will decrease. Therefore, the fusion enthalpy of the 3D printer filament of the present invention is greater than 0.0 J / g and less than 10.0 J / g. The lower limit of the fusion enthalpy of the filament is preferably greater than 0.0 J / g, and the lower the value, the more preferable it is. The upper limit of the fusion enthalpy of the filament is preferably 9.5 J / g, more preferably 8.5 J / g, and even more preferably 7.5 J / g.

[0079] The elastic modulus of the filament can be measured by the method described in Measurement Method 6 below. From the viewpoint of maintaining the flexibility of the filament in a suitable range, the elastic modulus of the 3D printer filament of the present invention is preferably 100.0 MPa or less, more preferably 50.0 MPa or less, even more preferably 35.0 MPa or less, particularly preferably 20.0 MPa or less, and most preferably 10.0 MPa or less. On the other hand, from the viewpoint of the printability of the filament, the elastic modulus of the filament is preferably 1.0 MPa or more, more preferably 1.5 MPa or more, and even more preferably 2.0 MPa or more.

[0080] The restoration rate of the filament can be measured in accordance with the method specified in JIS K7161 (2014), and more specifically, according to Measurement Method 7 described below. To ensure flexibility within a suitable range, the restoration rate of the 3D printer filament of the present invention is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. The higher the restoration rate of the filament, the more preferable it is, with the upper limit being 100%. In the present invention, the restoration rate is calculated by rounding to one decimal place; for example, a restoration rate of 99.9% is expressed as 100%.

[0081] The diameter of the 3D printer filament of the present invention is preferably 1.0 mm or more and 5.0 mm or less, more preferably 1.5 mm or more and 3.5 mm or less, even more preferably 1.6 mm or more and 3.3 mm or less, and most preferably 1.7 mm or more and 3.0 mm or less. In the field of 3D printers, filaments with a diameter of 1.0 mm or more and 5.0 mm or less are preferably used. The diameter of the filament is the longest linear distance between any two points on the circumference of a cross section of the filament cut perpendicular to the longitudinal direction. The longest linear distance between any two points on the circumference of a cross section of the filament cut perpendicular to the longitudinal direction can also be determined by measuring the linear distance between any two points on the circumference multiple times using digital calipers while rotating the filament circumferentially as needed without cutting the filament.

[0082] Furthermore, a uniform filament diameter along its length allows for stable extrusion from the nozzle. Therefore, in the 3D printer filament of the present invention, the diameter coefficient of variation, which is an indicator of diameter uniformity, is preferably 10% or less, more preferably 8% or less, even more preferably 5% or less, and most preferably 3% or less. Since a more uniform filament diameter is preferable, the lower limit of the filament diameter coefficient of variation is not specifically defined, but from a feasible perspective, 0% or more is preferred. In the present invention, the coefficient of variation is calculated by rounding to the nearest whole number. For example, a coefficient of variation of 0.1% is expressed as 0%. The coefficient of variation of the filament diameter can be calculated, for example, by the method described in Measurement Method 8 below.

[0083] The 3D printer filament of the present invention has high transparency. When the transparency of the filament is high, the transparency of the object obtained after 3D printing is high, making it suitable for use as a medical device. On the other hand, when the transparency of the filament is low and the filament is cloudy, the transparency of the object obtained after 3D printing will also be low. The transmittance of the filament is used as an indicator of the transparency of the filament, and the transmittance of the filament can be measured, for example, by the method described in Measurement Method 5 below. From the viewpoint of keeping the transparency of the filament in a suitable range, the transmittance of the 3D printer filament of the present invention is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. Note that the higher the transmittance of the filament, the better, with the upper limit being 100%.

[0084] The transparency of a molded body (modeled object) obtained by molding the 3D printer filament of the present invention can be measured, for example, by the method described in Measurement Method 9 below. In order to suitably use the modeled object as a medical device, the transparency of the modeled object is preferably "slightly transparent," and more preferably "transparent."

[0085] The 3D printer filament of the present invention may contain additives as long as the transparency is not impaired. However, water-soluble polymers or biodegradable polymers other than polyester copolymers are not considered additives.

[0086] Examples of additives include inorganic fillers, flame retardants, glass fibers, pharmaceuticals, and biomolecules.

[0087] Examples of inorganic fillers include glass fibers, carbon fibers, graphite, graphene, carbon nanotubes, gypsum fibers, mica, talc, glass flakes, wollastonite, potassium titanate, aluminum borate, boron nitride, aluminum nitride, calcium carbonate, silicon oxide (silica), titanium oxide, barium sulfate, magnesium oxide, calcium oxide, zinc oxide, titanium oxide, lead oxide, copper oxide, copper iodide, aluminum hydroxide, hydrotalcites, tin oxide, magnesium hydroxide, clay, white carbon, carbon black, inorganic pigments, molybdenum disulfide, metal powder, magnetic materials, and zeolites.

[0088] Examples of the glass fiber include chopped fiber, milled fiber, and flat glass fiber having a modified cross section, etc. From the viewpoint of electrical properties, glass fiber having a low dielectric constant can also be used.

[0089] It should be noted that some pharmaceuticals and biomolecules can be considered to be water-soluble or biodegradable polymers, but this does not apply to water-soluble or biodegradable polymers that are different from polyester copolymers.

[0090] <3D printer filament manufacturing method> The 3D printer filament of the present invention can be produced by feeding pellets of a composition that contains a polyester copolymer and does not contain a water-soluble polymer or a biodegradable polymer different from the polyester copolymer (hereinafter referred to as "polyester copolymer pellets") into an extruder and extruding them at a temperature of 90°C or higher and 150°C or lower. In other words, the method for producing a 3D printer filament of the present invention includes an extrusion molding step in which pellets of a composition that contains a polyester copolymer and does not contain a water-soluble polymer or a biodegradable polymer different from the polyester copolymer are extruded at a temperature of 90°C or higher and 150°C or lower.

[0091] To produce filaments containing additives, polyester copolymer pellets can be coated with the additives in advance, or the additives can be added to the extruder at the same time as the polyester copolymer pellets are added. Alternatively, filaments containing additives can be produced by dissolving the additives in a solution of polyester copolymer in a good solvent, adding a poor solvent, and re-precipitating the resulting composition containing the polyester copolymer and the additives, which is then added to the extruder and extruded at a temperature of 90°C to 150°C.

[0092] When producing filaments using polyester copolymers, the extrusion temperature is generally 70°C or higher and 250°C or lower. However, by extruding at a temperature of 90°C or higher and 150°C or lower, the melting enthalpy of the resulting filaments can be controlled within a suitable range, resulting in filaments with high permeability.

[0093] A 3D printer is a device that prints three-dimensional objects by layering resin or metal one layer at a time based on three-dimensional data. Examples of methods include fused deposition modeling, stereolithography (SLA or DLP), inkjet printing, powder sintering (SLS or SLM), and powder bonding. The filament of the present invention is particularly suitable for use in fused deposition modeling 3D printers. Fused deposition modeling 3D printers generally include a temperature-controllable nozzle, a feeder for feeding filament into the nozzle, and a tube for guiding the filament fed by the feeder. In fused deposition modeling 3D printers, the integrated part containing the nozzle, tube (and sometimes the feeder) and other parts is called the head. Fused deposition modeling is a method of melting the filament in the nozzle while moving the head horizontally to create a shape.

[0094] A molded body can be manufactured using the 3D printer filament of the present invention. Specifically, a molded body can be manufactured using the 3D printer filament of the present invention through the following melting step, layer forming step, and molded body forming step. Melting step: A step of melting the 3D printer filament of the present invention using a temperature-controllable nozzle. Layer formation process: The process of forming layers by ejecting molten filament while moving the 3D printer head horizontally. Molded body forming step: A step of repeating the layer forming step to stack the molten filaments to form a molded body.

[0095] In the melting process, in order to melt the 3D printer filament of the present invention, the temperature of the nozzle part is preferably 50°C or higher and 300°C or lower, more preferably 75°C or higher and 280°C or lower, and even more preferably 100°C or higher and 250°C or lower.

[0096] The shape of the molded article of the present invention may be, for example, a membrane (membrane, film, sheet), a plate (board), a rod (rod), a cylinder (pipe, tube), a filament (filament), a mesh (mesh), a bag (bag), a woven fabric, or a nonwoven fabric, or may be a complex shape that combines these.

[0097] Furthermore, the molded article of the present invention can be suitably used as a medical device, including, but not limited to, sutures, artificial bones, artificial skin, wound dressings, stents, DDS carriers, microneedles, and scaffolding materials for tissue and organ regeneration. [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 method 1: Weight average molecular weight) The polyester copolymer was dissolved in chloroform to a concentration of 1 mg / mL, and the solution was passed through a 0.45 μm syringe filter (DISMIC-13HP; manufactured by ADVANTEC) to remove impurities, and then gel permeation chromatography was performed under the following measurement conditions to measure the weight-average molecular weight of the polyester copolymer. Device name: Prominence (registered trademark; manufactured by Shimadzu Corporation) Mobile phase: Chloroform (for HPLC) (Wako Pure Chemical Industries, Ltd.) Flow rate: 1mL / min Column: TSKgel GMHHR-M (φ7.8 mm × 300 mm; manufactured by Tosoh Corporation) Detector: UV (254 nm), RI Column and detector temperature: 35°C Standard material: polystyrene

[0100] (Measurement Method 2: Molar Fraction and R Value of Each Residue) The purified polyester copolymer was dissolved in deuterated chloroform. 1H-NMR spectrum was measured to calculate the mole fraction (%) of monomer residues in the polyester copolymer.

[0101] As will be described later, the polyester copolymer in this example has two types of hydroxycarboxylic acid monomers (L,L-dilactide and ε-caprolactone) as its main structural units, and these two types of hydroxycarboxylic acid monomers are referred to as "monomer A" and "monomer B," respectively, and the molar fractions (%) of the monomer A residues and the monomer B residues were calculated. 1 By H homospin decoupling, the peaks of monomer A and monomer B were separated by signals derived from adjacent monomer residues of monomer A or monomer B, and the respective peak areas were quantified. Specifically, under the measurement conditions below, the methine group of L,L-dilactide (near 5.10 ppm) and the α-methylene group (near 2.35 ppm) and ε-methylene group (near 4.10 ppm) of ε-caprolactone were separated by signals derived from adjacent monomer residues of L,L-dilactide or ε-caprolactone, and the respective peak areas were quantified. Device name: JNM-ECZ400R (manufactured by JEOL Ltd.) 1 H homospin decoupling irradiation position: 1.66 ppm Solvent: deuterated chloroform Measurement temperature: room temperature

[0102] [AB] was calculated from the respective peak area ratios, and the R value was calculated using the following formula 1. R value = [AB] / (2[A][B]) × 100 Formula 1 [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

[0103] Here, [AB] is the molar 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, and specifically, the ratio of the number of AB and BA to the total number of AA, AB, BA, and BB.

[0104] (Measurement method 3: Biodegradability of filaments) D-PBS(-) (Fujifilm Wako Pure Chemical Industries, Ltd.) (10 mL) and a filament (30 mg) were placed in a 15 mL plastic centrifuge tube and allowed to stand at 50°C for 60 days. The filament was then washed with ion-exchanged water and dried under reduced pressure at 50°C for 24 hours.

[0105] Based on the weight-average molecular weight (Mw) of the filament after drying under reduced pressure and the weight-average molecular weight (Mw0) of the filament before immersion in D-PBS(-), the molecular weight reduction rate was calculated according to the following formula 2, and filaments with a molecular weight reduction rate of 60% or more were determined to be biodegradable. The weight-average molecular weight of each filament was measured using the method described in Measurement Method 1. Molecular weight reduction rate (%)=(1-Mw / Mw0)×100...Formula 2

[0106] (Measurement method 4: Melting enthalpy of filament, crystallization rate of polyester copolymer) A filament (approximately 5 mg) was placed in an aluminum pan and subjected to differential scanning calorimetry (DSC) under the following measurement conditions. From the measurement results under temperature conditions (A) to (B), the sum of the areas (J / g) of the melting peaks observed in the range of 25°C to 250°C was determined as the melting enthalpy (J / g) of the filament.

[0107] In addition, similar measurements were performed using the polyester copolymer, which is the raw material for the filament, and a homopolymer consisting only of the monomers that make up the polyester copolymer, instead of the filament.The heat of fusion was calculated from the measurement results under temperature conditions (D) to (E), and the crystallization rate of the monomer residues in the polyester copolymer was calculated using the following equation 3. Crystallinity ratio of monomer residue in polyester copolymer = (heat of fusion per unit weight of monomer residue in polyester copolymer) / {(heat of fusion per unit weight of homopolymer consisting of only monomer residue) × (weight fraction of monomer residue in polyester copolymer)} × 100 Equation 3 Device name: EXSTAR 6000 (Seiko Instruments Inc.) Temperature conditions: (A) 25℃ → (B) 250℃ (10℃ / min) → (C) 250℃ (5 minutes) → (D) -70℃ (10℃ / min) → (E) 250℃ (10℃ / min) → (F) 250℃ (5 minutes) → (G) 25℃ (100℃ / min) Standard material: Alumina

[0108] (Measurement method 5: Filament transmittance) The filament was cut into a length of 3 to 4 cm, and measurement was carried out under the following measurement conditions to read the value of Y. The measurement was carried out three times, and the arithmetic mean value was taken as the transmittance of the filament. Equipment name: SM-7-CH (manufactured by Suga Test Instruments Co., Ltd.) Optical system: 1 optical path optical system transmission Light source / field of view: C light 2° field of view Display:XYZ

[0109] (Measurement Method 6: Elastic Modulus of Filament) The filament was cut into a length of 3 to 4 cm, and a tensile test was performed under the following conditions in accordance with the method specified in JIS K7161 (2014) to measure the modulus of elasticity. The measurement was performed three times, and the arithmetic mean value was used as the modulus of elasticity of the filament. The modulus of elasticity was rounded to one decimal place. Device name: EZ-LX (Shimadzu Corporation) Initial length: 10mm Tensile speed: 500 mm / min Load cell: 1kN

[0110] (Measurement method 7: Filament recovery rate) The filament was cut into a length of 3 to 4 cm, and a tensile test was carried out in accordance with the method specified in JIS K7161 (2014) under the following measurement conditions to measure the recovery rate. Device name: EZ-LX (Shimadzu Corporation) 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

[0111] Specifically, two benchmark lines were drawn on the test specimen using an appropriate marker. The test specimen was in a relaxed state, and the benchmark lines were drawn accurately and clearly, perpendicular to the parallel portion of the test specimen and equidistant from the center of the test specimen. The test specimen was then stretched 90 mm at a tensile speed of 500 mm / min to generate tensile strain (Procedure 1).

[0112] Immediately after operation 1 (that is, the shape retention time was set to 0 seconds), the tensile strain was relaxed at a rate of 500 mm / min, and the distance between the grippers was returned to 10 mm (operation 2).

[0113] Immediately after Operation 2 (that is, the shape retention time was set to 0 seconds), the above-described Operations 1 and 2 were performed again.

[0114] This was repeated until Procedure 1 and Procedure 2 were performed 30 times in total, and the obtained values ​​of L1 and L2 were used to calculate the restoration rate according to the following formula 4. The values ​​for the restoration rate were rounded to the nearest whole number. Each measurement was performed three times, and the number average value was used as the restoration rate of the filament. Recovery rate (%)=(L1-L2) / (L1-L0)×100...Equation 4 L0: Initial length (gauge length before test) L1: Filament length when stretched to 90 mm (gauge length when stretched to 90 mm) (L1 means the value obtained by adding 90 mm to the initial length L0.) L2: Filament length after 30 repeated stretching (gauge distance after test)

[0115] (Measurement Method 8: Filament Diameter and Diameter Variation Coefficient) The diameter of the filament was measured at 10 random locations using a digital caliper, and the average value was rounded to the nearest tenth place to obtain the filament diameter. The coefficient of variation of the diameter was calculated using the standard deviation of the diameters at the 10 locations (sample standard deviation) using the following formula 5. The coefficient of variation was rounded to the nearest tenth place. Diameter variation coefficient (%) = standard deviation / average value × 100 Equation 5

[0116] (Measurement method 9: Transparency of 3D modeled objects) The evaluation was performed using a fused deposition modeling 3D printer with a temperature-controllable nozzle. Specifically, the nozzle of the 3D printer was moved horizontally while molten filament was ejected to form layers. This process was repeated to create a 50mm x 50mm x 1mm cube. The resulting cubes were visually inspected for transparency. Specifically, newspaper was placed on the opposite side of the cube. A cube was rated as "transparent" if it was sufficiently transparent that all the letters were legible; "slightly transparent" if it was transparent enough that most of the letters were legible; "semi-transparent" if the letters were illegible but still visible; and "opaque" if the letters were not visible.

[0117] (Synthesis Example 1) 50.0 g of L,L-dilactide (PURASORB® L; manufactured by PURAC) and 39.6 g of ε-caprolactone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were used as the monomers for the polyester copolymer, 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 added as a catalyst in 3.0 mL of ultra-dehydrated toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The reaction was carried out at 140°C for 9.5 hours to obtain a crude macromer. The resulting crude macromer was dissolved in 200 mL of chloroform and added dropwise to 3,000 mL of stirred hexane to obtain a precipitate. The precipitate was dried under reduced pressure at 50°C to obtain the macromer.

[0118] 50 g of the macromer, 2.1 g of the catalyst 4,4-dimethylaminopyridinium p-toluenesulfonate (synthetic product), and 0.80 g of 4,4-dimethylaminopyridine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were collected 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.

[0119] The reaction mixture was diluted with 220 mL of chloroform, and 470 mL of 0.5 M hydrochloric acid was added. The mixture was stirred for 30 minutes, and 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 decanted aqueous layer reached 7. The remaining organic layer was added dropwise to 3000 mL of stirred methanol to obtain a precipitate. This precipitate was dried under reduced pressure at 50 °C to obtain polyester copolymer 1. Measurements of polyester copolymer 2 were performed according to the methods described in Measurement Methods 1 and 2. The weight-average molecular weight was 170,000, and the molar fraction of dilactide residues was 50 mol % and caprolactone residues was 50 mol % when the sum of the number of all monomer residues contained in the entire polymer was 100 mol %, respectively. The R value was 0.61, and the crystallization rate of the dilactide residues was 0%.

[0120] (Synthesis Example 2) Polyester copolymer 2 was obtained by the same procedure as in Example 1, except that the reaction temperature for obtaining a crude macromer was changed to 130°C. Polyester copolymer 1 was measured according to the methods described in Measurement methods 1 and 2. The weight-average molecular weight was 280,000, and when the sum of the numbers of all monomer residues contained in the entire polymer was taken as 100 mol%, the molar fraction of dilactide residues was 50 mol%, the molar fraction of caprolactone residues was 50 mol%, the R value was 0.50, and the crystallization rate of the dilactide residues was 0%.

[0121] Example 1 Polyester copolymer 1 was cut into 5 mm squares and then fed into an extruder. The extrusion temperature was set to 90°C, and the filament was extruded to a diameter of 1.7 to 1.8 mm to obtain filament 1. The obtained filament 1 was subjected to the measurements described in measurement methods 3 to 9. The results are shown in Table 1.

[0122] Example 2 Filament 2 was obtained in the same manner as in Example 1, except that the extrusion temperature was changed to 120° C. The obtained filament 2 was subjected to the measurements described in Measurement Methods 3 to 9. The results are shown in Table 1.

[0123] Example 3 Filament 3 was obtained in the same manner as in Example 1, except that polyester copolymer 2 was used instead of polyester copolymer 1 and the extrusion temperature was changed to 100°C. The obtained filament 3 was subjected to the measurements described in measurement methods 3 to 9. The results are shown in Table 1.

[0124] Example 4 Filament 4 was obtained in the same manner as in Example 1, except that polyester copolymer 2 was used instead of polyester copolymer 1 and the extrusion temperature was changed to 140°C. The obtained filament 4 was subjected to the measurements described in measurement methods 3 to 9. The results are shown in Table 1.

[0125] Example 5 Filament 5 was obtained in the same manner as in Example 1, except that polyester copolymer 2 was used instead of polyester copolymer 1 and the extrusion temperature was changed to 150°C. The obtained filament 5 was subjected to the measurements described in measurement methods 3 to 9. The results are shown in Table 1.

[0126] (Comparative Example 1) Polyester copolymer 2 was cut into 5 mm squares and then coated with PEG (Sigma-Aldrich, weight-average molecular weight 10,000) that had been crushed using a mortar and pestle to obtain a composition. The composition was placed in an extruder, the extrusion temperature was set to 110°C, and the filament was extruded to a diameter of 1.7 to 1.8 mm to obtain filament 6. The obtained filament 6 was subjected to the measurements described in measurement methods 3 to 9. The results are shown in Table 1.

[0127] (Comparative Example 2) Polyester copolymer 2 was dissolved in chloroform (10 mL per 1 g of polymer), and PLA (Nature3D) (0.1 g per 1 g of polymer) was then dissolved in the solution. The solution was then added to stirred hexane (6 mL per 1 mL of added chloroform) to obtain a precipitate. This precipitate was dried under reduced pressure at 50°C to obtain a composition. The composition was cut into 5 mm squares and then placed in an extruder. The extrusion temperature was set to 200°C, and the filament was extruded to a diameter of 1.7 to 1.8 mm to obtain filament 7. The obtained filament 7 was subjected to the measurements described in Measurement Methods 3 to 9. The results are shown in Table 1.

[0128] (Comparative Example 3) Filament 8 was obtained in the same manner as in Example 1, except that polyester copolymer 2 was used instead of polyester copolymer 1 and the extrusion temperature was changed to 200°C. The obtained filament 8 was subjected to the measurements described in measurement methods 3 to 9. The results are shown in Table 1. The filament was extruded so that the diameter would be 1.7 to 1.8 mm, but the diameter of the finally obtained filament was 1.5 mm. The results are shown in Table 1.

[0129] Comparative Example 4 The same procedure as in Example 1 was carried out except that polyester copolymer 2 was used instead of polyester copolymer 1 and the extrusion temperature was changed to 80°C, but the pellets (polyester copolymer cut into 5 mm squares) did not soften sufficiently and could not be molded into filaments. The results are shown in Table 1.

[0130] [Table 1]

Claims

1. a polyester copolymer, and no water-soluble or biodegradable polymer different from the polyester copolymer; A filament for a 3D printer having a melting enthalpy of greater than 0.0 J / g and less than or equal to 10.0 J / g.

2. The filament of claim 1 , consisting solely of said polyester copolymer.

3. The polyester copolymer is a polyester copolymer having two types of ester bond-forming monomer residues as main structural units, and when the two types of ester bond-forming monomers are referred to as "monomer A" and "monomer B," respectively, the polyester copolymer satisfies the following (1) and (2): (1) The R value represented by the following formula is 0.45 or more and 0.99 or less. R value = [A B] / (2 [A] [B]) x 100 [A]: Molar fraction of monomer A residue in the polyester copolymer [B]: Molar fraction of monomer B residue in polyester copolymer [AB]: Molar fraction of structures (AB and BA) in which a monomer A residue and a monomer B residue are adjacent to each other in the polyester copolymer (2) The crystallinity of at least one of the monomer A residue and the monomer B residue is less than 14%.

4. The filament according to claim 1 or 2, wherein the two types of ester bond-forming monomers are two types selected from the group consisting of hydroxycarboxylic acids, lactones, and lactides.

5. 3. The method for producing a filament according to claim 1, comprising an extrusion molding step of extruding pellets of a composition containing a polyester copolymer and not containing a water-soluble polymer or a biodegradable polymer different from the polyester copolymer at a temperature of 90°C or higher and 150°C or lower.

6. A molded article obtained by molding the filament according to claim 1 or 2.

7. a melting step of melting the filament according to claim 1 or 2 using a temperature-controllable nozzle; a layer forming step of forming a layer by ejecting the molten filament while horizontally moving the head of the 3D printer; A method for manufacturing a molded body using a 3D printer, comprising: a molded body formation process in which the melted filaments are stacked by repeating the layer formation process to form a molded body.

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