Biodegradable polyester resin, method for producing the same, and biodegradable polyester film containing the same

Abstract

An embodiment relates to a biodegradable polyester resin, a method for producing the same, and a biodegradable polyester film containing the same. The biodegradable polyester resin has a peak at a specific diffraction angle (2θ) in an X-ray diffraction spectrum (XRD) and satisfies a specific crystal size, thereby being excellent in crystallinity and thermal stability and capable of improving all of mechanical properties, dimensional stability, and moldability. Therefore, the biodegradable polyester resin according to the embodiment can be utilized in various fields requiring heat resistance, mechanical properties, dimensional stability, and moldability, such as packaging materials like disposable bags and food containers, and automotive interior materials, and can exhibit excellent properties.

Description

Technical Field

[0001] The implementation example relates to a biodegradable polyester resin, a method for producing the same, and a biodegradable polyester film containing the same.

Background Art

[0002] In recent years, as concerns about environmental problems have increased, solutions to the disposal problems of various daily necessities, particularly disposable products, have been sought. Specifically, although polymer materials are inexpensive and have excellent properties such as processability, they are widely used for manufacturing various products such as films, fibers, packaging materials, bottles, and containers. However, when the used products reach the end of their life, harmful substances are emitted during incineration, and it has the drawback that it takes hundreds of years depending on the type to be completely decomposed in nature.

[0003] In order to overcome such limitations of polymers, research on biodegradable polymers that are decomposed in a shorter time has been actively conducted. As biodegradable polymers, polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), polybutylene succinate adipate (PBSA), etc. are used. However, compared with non-degradable resins such as polyethylene terephthalate (PET), their crystallinity and thermal stability are low. Therefore, there is an actual need for research on biodegradable polymer resins that can improve dimensional stability and moldability while not reducing biodegradability and mechanical properties and having excellent crystallinity and thermal stability.

[0004] As an example, Patent Document 1 discloses a biodegradable resin composition in which a crystal nucleating agent is added to a biodegradable resin to improve crystallinity. However, there are limitations in improving crystallinity using a crystal nucleating agent, and it must be carried out at a low temperature for a long time for the stabilization of crystal nuclei, and there are problems in that the process and its conditions are complicated.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, the present exemplary embodiment aims to provide a biodegradable polyester resin that is excellent in crystallinity and thermal stability and can improve any of mechanical properties, dimensional stability, and moldability, a method for producing the same, and a biodegradable polyester film containing the same.

Means for Solving the Problems

[0007] The biodegradable polyester resin according to one exemplary embodiment contains a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue, and has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in an X-ray diffraction spectrum (XRD), and the crystal size according to the following formula 1 is 50 Å to 80 Å.

[0008] [Formula 1] JPEG2025522302000002.jpg1264In the above formula 1, λ is the wavelength (nm) in the X-ray diffraction spectrum (XRD), β is the full width at half maximum (FWHM) at the diffraction angle (2θ), θ is half of the value of the diffraction angle (2θ), The X-ray diffraction spectrum (XRD) was measured at a scan rate of 5° / min at diffraction angles (2θ) of 10° to 35°.

[0009] A method for producing a biodegradable polyester resin according to another embodiment includes mixing and pre-treating a diol and an aromatic dicarboxylic acid to obtain a slurry, subjecting the slurry to a primary esterification reaction, then adding an aliphatic dicarboxylic acid, or a diol and an aliphatic dicarboxylic acid, and subjecting it to a secondary esterification reaction to obtain a prepolymer, and subjecting the prepolymer to a polycondensation reaction to obtain a polymer. The biodegradable polyester resin contains a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue. The biodegradable polyester resin has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in the X-ray diffraction spectrum (XRD), and the crystal size of the biodegradable polyester resin according to Formula 1 is 50 Å to 80 Å.

[0010] Another biodegradable polyester film according to an embodiment includes a biodegradable polyester resin. The biodegradable polyester resin contains a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue. The biodegradable polyester resin has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in the X-ray diffraction spectrum (XRD), and the crystal size of the biodegradable polyester resin according to Formula 1 is 50 Å to 80 Å.

Advantages of the Invention

[0011] The biodegradable polyester resin according to the embodiment has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in the X-ray diffraction spectrum (XRD), and by satisfying a specific range of crystal sizes according to Formula 1, it is excellent in crystallinity and thermal stability, and can improve all of mechanical properties, dimensional stability, and moldability.

[0012] Therefore, the biodegradable polyester resin can be utilized in various fields that require heat resistance, mechanical properties, dimensional stability, and moldability, such as packaging materials like disposable bags and food containers, and automotive interior materials, and can exhibit excellent properties.

Brief Description of the Drawings

[0013]

Figure 1

Modes for Carrying Out the Invention

[0014] Hereinafter, the invention will be described in detail with reference to implementation examples. The implementation examples are not limited to the content disclosed below, and can be modified into various forms without changing the gist of the invention.

[0015] In this specification, when a certain part says that a certain component "includes", unless there is a contrary description, it does not exclude other components, but means that it may further include other components.

[0016] Also, all numerical ranges indicating physical property values, dimensions, etc. of the components described in this specification should be understood to be modified by the term "about" in all cases unless otherwise specified.

[0017] In this specification, terms such as first, second, primary, secondary, etc. are used to describe various components, and the components are not limited by the terms. The terms are only used for the purpose of distinguishing one component from another.

[0018] Polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), polybutylene succinate adipate (PBSA), etc., which are widely used as biodegradable polymers, have lower crystallinity and thermal stability compared to non-degradable resins such as polyethylene terephthalate (PET).

[0019] Specifically, in order to manufacture molded products such as films using resins, processes such as stretching, extrusion, blowing, and injection are carried out. Polyethylene terephthalate (PET), a non-degradable resin, is excellent in crystallinity and has a high crystallization rate. Therefore, in the manufacturing process, orientation crystals and thermal crystals are generated by stretching orientation, resulting in excellent mechanical properties and dimensional stability. However, in order to solve environmental problems, there is a problem that an additional recycling process needs to be carried out.

[0020] On the other hand, resins copolymerized with two or more monomers (co-monomers) such as polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), polybutylene succinate adipate (PBSA), etc., or resins containing L-type and D-type isomers such as polylactic acid (PLA) are biodegradable polymers, but have low crystallinity and a slow crystallization rate. Therefore, orientation crystals and thermal crystals do not occur due to stretching orientation, so they have lower thermal stability or a higher thermal shrinkage rate compared to non-degradable resins such as polyethylene terephthalate (PET). In particular, such biodegradable polymers have low dimensional stability, which is the ability to maintain their original shape under various environmental conditions, making it difficult to apply them to various fields.

[0021] However, the biodegradable polyester resin according to the implementation example has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in the X-ray diffraction spectrum (XRD). By satisfying the crystal size of 50 Å to 80 Å according to Formula 1, the crystallinity is improved, the thermal stability is excellent, and any of the mechanical properties, dimensional stability, and moldability can be improved. In particular, the biodegradable polyester resin according to the implementation example can further improve the crystallinity and thermal stability by containing an aromatic dicarboxylic acid having a specific particle size and the standard deviation with respect thereto.

[0022] Therefore, the biodegradable polyester resin can be utilized in various fields requiring heat resistance, mechanical properties, dimensional stability, and moldability, such as packaging materials like disposable bags and food containers, and automotive interior materials, and can exhibit excellent properties.

[0023] [Biodegradable Polyester Resin] The biodegradable polyester resin according to one implementation example contains a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue, has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in the X-ray diffraction spectrum (XRD), and the crystal size according to the following Formula 1 is 50 Å to 80 Å.

[0024] [Formula 1] In the above Formula 1, λ is the wavelength (nm) in the X-ray diffraction spectrum (XRD), β is the full width at half maximum (FWHM) at the diffraction angle (2θ), θ is half of the diffraction angle (2θ), The X-ray diffraction spectrum (XRD) was measured at a scan speed of 5° / min at diffraction angles (2θ) of 10° to 35°.

[0025] The X-ray diffraction spectrum (XRD) can be measured using a wide angle X-ray scattering device (WAXD), but is not limited thereto.

[0026] For example, the crystal size of the biodegradable polyester resin according to the formula 1 can be 50 Å to 80 Å, 52 Å to 80 Å, 55 Å to 80 Å, 55 Å to 78 Å, 55 Å to 76 Å, 57 Å to 76 Å, 58 Å to 75 Å, 58 Å to 73 Å, or 60 Å to 72 Å. By satisfying the range of the crystal size of the biodegradable polyester resin, it is possible to improve both crystallinity and thermal stability without degrading mechanical properties.

[0027] In addition, the full width at half maximum (FWHM) at the diffraction angle (2θ) can be less than 1.0° / 2θ. Specifically, the full width at half maximum means the width of the value half of the peak value (intensity), and the full width at half maximum (FWHM) at each diffraction angle (2θ) can be 0.9° / 2θ or less, 0.85° / 2θ or less, 0.8° / 2θ or less, 0.75° / 2θ or less, 0.7° / 2θ or less, 0.65° / 2θ or less, 0.6° / 2θ or less, or 0.55° / 2θ or less. By satisfying the range of the full width at half maximum (FWHM) at each diffraction angle (2θ), it is possible to further improve crystallinity and thermal stability without degrading mechanical properties.

[0028] The crystallization temperature (Tc) of the biodegradable polyester resin measured by differential scanning calorimetry (DSC) can be 35°C to 65°C. For example, the crystallization temperature (Tc) of the biodegradable polyester resin measured by differential scanning calorimetry can be 35°C to 65°C, 35°C to 60°C or 40°C to 65°C.

[0029] Also, the heat of crystal fusion (Hmc1) of the biodegradable polyester resin measured by a differential scanning calorimeter can be 19.1 J / g or more. For example, the heat of crystal fusion (Hmc1) of the biodegradable polyester resin measured by a differential scanning calorimeter can be 19.3 J / g or more, 19.4 J / g or more, 19.5 J / g or more, or 19.6 J / g or more.

[0030] By the crystallization temperature and the heat of crystal fusion satisfying the above ranges respectively, the mechanical properties are not deteriorated, and the crystallinity and thermal stability can be further improved.

[0031] Also, the crystallinity of the biodegradable polyester resin measured by a differential scanning calorimeter can be 8% or more. For example, the crystallinity of the biodegradable polyester resin measured by a differential scanning calorimeter can be 9% or more, 11% or more, 14% or more, or 15% or more, and can be 8% - 20%, 9% - 19.5%, 11% - 18%, 14% - 17.5%, or 15% - 17%.

[0032] The crystallinity can be calculated as a percentage of the value obtained by dividing the enthalpy of fusion (△H m ) measured using a differential scanning calorimeter by the enthalpy of fusion (△H c ) in 100% crystals. Specifically, it can be calculated by the following formula C.

[0033] [Formula C] JPEG2025522302000004.jpg1483

[0034] Specifically, the differential scanning calorimeter (DSC) can be specifically a modulated differential scanning calorimeter (MDSC), and more specifically a temperature-modulated differential scanning calorimeter (TMDSC), but is not limited thereto.

[0035] Specifically, the crystallization temperature, the heat of crystal fusion, and the enthalpy of fusion are measured in a differential scanning calorimeter (DSC) mode by a primary scan (1 st scan) or a secondary scan (2nd It can be measured by scanning, and the glass transition temperature (Tg), crystallization temperature (Tc), and melting point (Tm) can be confirmed from the heat flow curve obtained by scanning.

[0036] More specifically, after heating from 40°C to 180°C at a rate of 10°C / min, the exothermic peak measured while cooling to -50°C at a rate of 10°C / min is the crystallization temperature (Tc). Then, the first endothermic peak measured while heating from -50°C to 180°C at a rate of 10°C / min is the glass transition temperature (Tg), and the second endothermic peak is the melting point (Tm).

[0037] At this time, the integral value at the crystallization temperature (Tc) can be calculated as the heat of crystal melting (Hmc1), and the integral value at the melting point (Tm) can be calculated as the melting enthalpy (ΔH m ).

[0038] According to one embodiment, the biodegradable polyester resin contains a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue.

[0039] Specifically, the diol residue may include a first diol residue and a second diol residue each containing a residue of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof. Further, the biodegradable polyester resin may include a first repeating unit containing a first diol residue and a residue of an aromatic dicarboxylic acid, and a second repeating unit containing a second diol residue and a residue of an aliphatic dicarboxylic acid. By including the first repeating unit and the second repeating unit, the biodegradability and mechanical properties of the biodegradable polyester resin can be improved.

[0040] The diol residue may include residues of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or derivatives thereof as the first diol residue and the second diol residue. The first diol residue and the second diol residue may be the same as or different from each other. Specifically, the diol residue may include residues of 1,4-butanediol, 1,2-ethanediol, or derivatives thereof, and more specifically, may include residues of 1,4-butanediol or derivatives thereof. When the diol residue includes a residue of 1,4-butanediol, it may be further advantageous in terms of improving biodegradability, mechanical properties such as tensile strength, and heat resistance.

[0041] Further, the residue of the aromatic dicarboxylic acid includes residues of terephthalic acid, dimethyl terephthalate, or derivatives thereof, and the residue of the aliphatic dicarboxylic acid may include residues of adipic acid, succinic acid, sebacic acid, or derivatives thereof.

[0042] According to one implementation example, the aromatic dicarboxylic acid may include terephthalic acid. Specifically, the terephthalic acid has a number-based average particle diameter (D50) measured by a particle size analyzer Microtrac S3500 in a particle size distribution (PSD) of 10 μm to 400 μm, and the standard deviation with respect to the average particle diameter (D50) may be 100 or less.

[0043] Specifically, when the aromatic dicarboxylic acid includes terephthalic acid, the terephthalic acid has complete crystallinity, is a white crystal that sublimes at about 300 °C without a melting point, and has a very low solubility in the diol, so the uniformity of the reaction may be low. The aromatic dicarboxylic acid according to the implementation example may further improve crystallinity and thermal stability by including terephthalic acid whose average particle diameter and standard deviation with respect to it satisfy the above range.

[0044] For example, the average particle size (D50) of the terephthalic acid can be 15 μm to 400 μm, 20 μm to 250 μm, 35 μm to 215 μm, 40 μm to 180 μm, 50 μm to 165 μm, 75 μm to 150 μm, or 90 μm to 130 μm.

[0045] Moreover, the standard deviation with respect to the average particle size (D50) of the terephthalic acid is 90 or less, 80 or less, 65 or less, 50 or less, or 30 or less, and can be 5 to 90, 5 to 70, 10 to 60, 12 to 45, 15 to 40, or 15 to 30.

[0046] By the average particle size of the terephthalic acid and the standard deviation with respect to it respectively satisfying the above ranges, the solubility in the diol can be improved, and it can be more advantageous in terms of the esterification reaction rate in the subsequent process. Specifically, by the average particle size of the terephthalic acid and the standard deviation with respect to it respectively satisfying the above ranges, the physical properties are not deteriorated, and the esterification reaction time can be shortened by 1.5 times or more, so it can be more preferable in terms of reaction efficiency.

[0047] Moreover, when the average particle size (D50) of the terephthalic acid is less than 10 μm, it is not preferable because the average particle size (D50) is too small and can be converted into secondary particles aggregated from single primary particles. When the average particle size (D50) of the terephthalic acid exceeds 400 μm, since the average particle size (D50) is too large, the solubility in the diol decreases, the esterification reaction rate becomes slow, and the uniformity of the reaction can also decrease.

[0048] According to another embodiment, the aromatic dicarboxylic acid may include dimethyl terephthalate. Specifically, the dimethyl terephthalate can be in a range similar to the average particle size (D50) of the terephthalic acid and the standard deviation with respect to it when measured in a molten state or in a particulate state.

[0049] Specifically, the first repeating unit may include a residue of 1,4-butanediol or a derivative thereof and a residue of terephthalic acid or a derivative thereof. Alternatively, the first repeating unit may include a residue of 1,4-butanediol or a derivative thereof and a residue of dimethyl terephthalate or a derivative thereof.

[0050] Further, the second repeating unit may include a residue of 1,4-butanediol or a derivative thereof and a residue of adipic acid or a derivative thereof. Alternatively, the second repeating unit may include a residue of 1,4-butanediol or a derivative thereof and a residue of succinic acid or a derivative thereof.

[0051] By the first repeating unit and the second repeating unit satisfying the above configuration, biodegradability, mechanical properties such as tensile strength, and heat resistance can be further improved.

[0052] Specifically, in order for the biodegradable polyester resin according to the implementation example to be excellent in biodegradability and to improve mechanical properties, dimensional stability, moldability, and productivity, it is very important to adjust the number of the first repeating unit and the second repeating unit that constitute the biodegradable polyester resin.

[0053] Generally, polyester resins, for example, polybutylene adipate terephthalate (PBAT)-based resins are excellent in flexibility but have weak impact resistance, so they are prone to tearing and rupture, and due to their weak stiffness, their applications have been limited. However, the biodegradable polyester resin according to the implementation example can improve any of biodegradability, mechanical properties, dimensional stability, moldability, and productivity by adjusting the number of the first repeating unit and the second repeating unit.

[0054] Specifically, the ratio (X / Y) of the number (X) of the first repeating units and the number (Y) of the second repeating units can be 0.8 to 3.0. For example, the ratio (X / Y) of the number (X) of the first repeating units and the number (Y) of the second repeating units can be 0.8 to 2.9, 0.8 to 2.55, 0.83 to 2.15, 0.85 to 1.9, 0.85 to 1.65, 0.9 to 1.4, 0.9 to 1.2, or 0.95 to 1.05.

[0055] By the ratio (X / Y) of the number (X) of the first repeating units and the number (Y) of the second repeating units satisfying the above range, mechanical properties such as tensile strength can be improved. In particular, when a blowing process is performed using the biodegradable polyester resin, bubble stability can be improved, such as the bubbles bursting without the bubbles having a uniform shape. Further, when an injection process is performed using the biodegradable polyester resin, it is possible to effectively prevent the occurrence of fish eyes and fusion between the film surfaces, so that the quality and processability can be improved.

[0056] Specifically, when the number of the second repeating units is the same as the number of the first repeating units or more than the number of the first repeating units, excellent durability and heat resistance can be maintained during a specific period, the biodegradability is not reduced, and after the use is completed, biodegradation can be sufficiently effectively achieved.

[0057] Also, the number (X) of the first repeating units can be 100 to 900. For example, the number (X) of the first repeating units can be 105 to 750, 130 to 500, 145 to 350, 150 to 300, 165 to 240, 170 to 190.

[0058] The number (Y) of the second repeating units can be 110 to 1100. For example, the number (Y) of the second repeating units can be 115 to 1000, 135 to 850, 150 to 600, 155 to 450, 160 to 280, 165 to 230, or 175 to 205.

[0059] By the number of the first repeating units and the number of the second repeating units each satisfying the above range, biodegradability, mechanical properties, heat resistance, dimensional stability, moldability, and productivity can all be improved.

[0060] In particular, the second repeating unit containing the second diol residue and the aliphatic dicarboxylic acid residue consists of a linear chain and thus contains an aliphatic dicarboxylic acid residue that can affect the adhesion properties. Therefore, the crystallinity can be controlled according to its content, and by satisfying the above range, the improvement of mechanical properties such as tensile strength and heat resistance can be maximized.

[0061] According to one implementation example, the biodegradable polyester resin may contain the first repeating unit and the second repeating unit in the form of a block copolymer.

[0062] Specifically, when the first repeating unit and the second repeating unit are contained in the form of a block copolymer, when oriented crystals are formed in the stretching process using the biodegradable polyester resin, it is advantageous for generating microcrystals and no steric hindrance occurs, so that crystallization can be achieved sufficiently effectively. Therefore, the biodegradable polyester resin containing the first repeating unit and the second repeating unit in the form of a block copolymer can induce well-oriented crystals by stretching and form a dense crystal structure, so that the mechanical properties such as the tensile strength of the molded product, especially the film, and the dimensional stability can be maximized.

[0063] Also, the biodegradable polyester resin may contain a cellulose-based additive. By the biodegradable polyester resin containing a cellulose-based additive, biodegradability, crystallinity, thermal stability, mechanical properties such as tensile strength, and dimensional stability can be further improved.

[0064] Specifically, the cellulose-based additive can be one or more selected from the group consisting of cellulose nanocrystals, cellulose nanofibers, microfibrillated cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, cellulose acetate, methyl cellulose, ethyl cellulose, propyl cellulose, butyl cellulose, pentyl cellulose, hexyl cellulose, and cyclohexyl cellulose. Cellulose nanocrystals or cellulose nanofibers are preferred in terms of strength and thermal properties, but are not limited thereto.

[0065] The average particle size of the cellulose-based additive is 100 nm or more, and the particle size deviation can be 32% or less. For example, the average particle size of the cellulose-based additive is 100 nm or more, 120 nm or more, 140 nm or more, or 150 nm or more, and is 100 nm to 1500 nm, 115 nm to 1200 nm, 120 nm to 900 nm, 135 nm to 650 nm, 145 nm to 500 nm, 150 nm to 350 nm, 152 nm to 290 nm, 155 nm to 215 nm, or 155 nm to 190 nm, and the particle size deviation of the cellulose-based additive can be 31% or less, 30% or less, or 29.5% or less.

[0066] The average particle size and particle size deviation of the cellulose-based additive can be measured by a nanoparticle size analyzer (ex. Zetasizer Nano ZS). Specifically, for the cellulose-based additive, using a Zetasizer Nano ZS (Malvern), the average particle size and particle size deviation can be calculated with Zetasizer software. More specifically, based on the principle of dynamic light scattering (DLS) at a temperature of 25 °C and a measurement angle of 175 °, the average particle size and particle size deviation were measured. At this time, the value of the peak derived from the polydispersity index (PDI) in the 0.5 confidence interval was measured as the particle size.

[0067] Further, the biodegradable polyester resin may contain the cellulose-based additive at 3000 ppm or less. For example, the content of the cellulose-based additive is 2500 ppm or less, 2000 ppm or less, 1200 ppm or less, 900 ppm or less, 800 ppm or less, or 650 ppm or less based on the total weight of the biodegradable polyester resin, and may be 100 ppm to 3000 ppm, 150 ppm to 2200 ppm, 180 ppm to 1000 ppm, 350 ppm to 850 ppm, 400 ppm to 700 ppm, or 520 ppm to 650 ppm.

[0068] Also, the cellulose-based additive may be one that has been subjected to bead mill pretreatment, ultrasonic pretreatment, stirring pretreatment, or hydrophobization pretreatment. Specifically, the cellulose-based additive may be one in which the water-dispersed cellulose-based additive has been subjected to bead mill pretreatment, ultrasonic pretreatment, stirring pretreatment, or hydrophobization pretreatment.

[0069] First, the bead mill pretreatment can be performed using a wet milling device such as a vertical mill or a horizontal mill. A horizontal mill may be preferable in that it can hold a larger amount of beads inside the chamber, reducing mechanical uneven wear, reducing bead wear, and being easier to maintain, but it is not limited thereto.

[0070] The bead mill pretreatment can be performed using one or more beads selected from the group consisting of zirconium, zircon, zirconia, quartz, and aluminum oxide.

[0071] Specifically, the bead mill pretreatment can be performed using beads having a diameter of 0.3 mm to 1 mm. For example, the diameter of the beads can be 0.3 mm to 1 mm, 0.35 mm to 0.95 mm, 0.4 mm to 0.9 mm, 0.45 mm to 0.7 mm, 0.45 mm to 0.85 mm, or 0.45 mm to 0.6 mm. By satisfying the above range of the bead diameter, the dispersibility of the cellulose-based additive can be further improved. If the bead diameter exceeds the above range, the average particle size and particle size deviation of the cellulose-based additive may increase, resulting in a decrease in dispersibility.

[0072] In addition, for the bead mill pretreatment, it may be preferable to use beads with a specific gravity higher than that of the cellulose-based additive in terms of being able to transfer sufficient energy. For example, the beads are one or more selected from the group consisting of zirconium, zircon, zirconia, quartz, and aluminum oxide, which have a higher specific gravity than the water-dispersed cellulose-based additive, and zirconium beads with a specific gravity 4 times or more higher than that of the water-dispersed cellulose-based additive may be preferable, but it is not limited thereto.

[0073] The bead mill pretreatment can be performed at a linear velocity of 20 m / sec or less with the chamber filled with 80% or more beads. For example, the bead mill pretreatment can be performed at a bead filling rate in the chamber of 80% or more, 81% or more, or 83% or more, and a linear velocity of 18 m / sec or less, 17 m / sec or less, or 16 m / sec or less. By satisfying the above range of the filling rate and the linear velocity, the effect of the bead mill pretreatment, that is, the improvement of dispersibility, can be maximized.

[0074] In addition, the ultrasonic pretreatment is a method of physically crushing or pulverizing nanoparticles by the waves generated by emitting ultrasonic waves of 20 kHz into the solution.

[0075] Specifically, the ultrasonic pretreatment can be performed with an energy amount of 30,000 J or less for a time of less than 30 minutes. For example, the ultrasonic pretreatment can be performed with an energy amount of 30,000 J or less, 26,000 J or less, 24,500 J or less, 22,000 J or less, 19,500 J or less, 16,500 J or less, or 16,000 J or less for a time of less than 30 minutes, 23 minutes or less, 20 minutes or less, 13 minutes or less, 10 minutes or less, 6 minutes or less, or 3 minutes or less. By satisfying the range of the energy amount and the implementation time of the ultrasonic pretreatment, the effect of the ultrasonic pretreatment, that is, the improvement of dispersibility, can be maximized.

[0076] According to one implementation example, the cellulose-based additive can be one that has been pretreated by a bead mill or ultrasonic pretreatment. Or, the cellulose-based additive can be one that has been subjected to both bead mill pretreatment and ultrasonic pretreatment. At this time, it may be preferable in terms of preventing re-aggregation and improving dispersibility that ultrasonic pretreatment is performed after bead mill pretreatment.

[0077] When the cellulose-based additive, specifically, the water-dispersed cellulose-based additive, has been pretreated by a bead mill or ultrasonic pretreatment, the dispersibility can be maximized, so the number of cellulose particles can be increased. Specifically, the number of cellulose particles can be larger at the same content in the additionally bead mill-pretreated or ultrasonic-pretreated water-dispersed cellulose-based additive than in the water-dispersed cellulose-based additive that has not been bead mill-pretreated or ultrasonic-pretreated. Therefore, when the cellulose-based additive is additionally bead mill-pretreated or ultrasonic-pretreated, the dispersion stability can be further improved.

[0078] Also, the stirring pretreatment can be performed at 10,000 rpm or less for 1 minute to 90 minutes. For example, the stirring pretreatment is performed by a stirrer or a homogenizer and can be performed at 9,500 rpm or less, 6,500 rpm or less, 5,000 rpm or less, 3,500 rpm or less, 2,500 rpm or less, 2,200 rpm or less, or 2,000 rpm or less for 10 minutes to 90 minutes, 30 minutes to 85 minutes, 45 minutes to 70 minutes, or 50 minutes to 65 minutes.

[0079] Further, the hydrophobic pretreatment can be performed by one or more methods selected from the group consisting of acetylation, silanization, crosslinking, fluorination, addition of AKD (Alkyl Ketene Dimer), and addition of ASA (alkyl succinic anhydride).

[0080] Specifically, by the hydrophobic treatment method, the dimensional stability can be further improved by substituting a part of the hydroxyl groups of the cellulose additive with hydrophobic groups having a reduced affinity for moisture. For example, the silanization can be performed using MTMS (methyltrimethoxysilane), TMOS (tetramethoxysilane), DMDMS (dimethoxydimethylsilane), MAPTMS (3-methyl-acryl-oxypropyl trimethoxy silane), TBOT (titanium butoxide), or TMPS (trimethoxy-phenyl-silane), but is not limited thereto.

[0081] According to one implementation example, the biodegradable polyester resin may contain an inorganic filler including one or more selected from the group consisting of titanium dioxide (TiO2), silicon dioxide (SiO2), calcium carbonate (CaCo3), talc, aluminum oxide (Al2O3), calcium oxide (CaO), and potassium oxide (K2O).

[0082] The inorganic filler may have a number-based average particle size (D50) measured by a particle size analyzer Microtrac S3500 in a particle size distribution (PSD) of 100 μm or less. For example, the inorganic filler may have a number-based average particle size (D50) measured by a particle size analyzer Microtrac S3500 in a particle size distribution (PSD) of 85 μm or less, 70 μm or less, 50 μm or less, 25 μm or less, 10 μm or less, 5 μm or less, 3 μm or less, or 1 μm or less.

[0083] Further, the specific surface area of the inorganic filler is 100 m 2 / g or more. For example, the specific surface area of the inorganic filler is 100 m 2 / g or more, 105 m 2 / g or more, or 110 m 2 / g or more.

[0084] By including an inorganic filler that satisfies the average particle size (D50) and specific surface area, mechanical properties such as crystallinity, thermal stability, and tensile strength, and dimensional stability can be further improved.

[0085] The specific surface area can be measured using a BET (Brunauer Emmett Teller) specific surface area analyzer. For example, the specific surface area of the inorganic filler can be measured using ASAP 2020 (Micromeritics).

[0086] Specifically, the biodegradable polyester resin may contain an inorganic filler of 5000 ppm or less based on the total weight of the biodegradable polyester resin. For example, the content of the inorganic filler is 5000 ppm or less, 3500 ppm or less, or 2000 ppm or less based on the total weight of the biodegradable polyester resin, and is 10 ppm to 5000 ppm, 15 ppm to 4000 ppm, 25 ppm to 3500 ppm, 35 ppm to 2500 ppm, 50 ppm to 2000 ppm, 50 ppm to 5000 ppm, 500 ppm to 5000 ppm, 1500 ppm to 5000 ppm, or 2000 ppm to 5000 ppm.

[0087] When the biodegradable polyester resin contains the inorganic filler within the above content range, the biodegradability is not reduced, and the heat shrinkage rate can be controlled within an appropriate range.

[0088] Further, the biodegradable polyester resin may further contain one or more resins selected from the group consisting of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), polybutylene succinate adipate (PBSA), polybutylene adipate (PBA), and polycaprolactone (PCL). By the biodegradable polyester resin further containing the resin, it may be more advantageous for adjusting properties such as mechanical properties.

[0089] Also, the number of carboxyl group end groups of the biodegradable polyester resin may be 50 eq / ton or less. For example, the number of carboxyl group end groups of the biodegradable polyester resin may be 50 eq / ton or less, 48 eq / ton or less, 45 eq / ton or less, 42 eq / ton or less, or 35 eq / ton or less. By adjusting the number of carboxyl group end groups within the above range, in the process of manufacturing a molded article such as a film using the biodegradable polyester resin, the occurrence rate of polymer degradation can be reduced, and both mechanical properties such as tensile strength and heat resistance can be improved.

[0090] Also, the intrinsic viscosity (IV) of the biodegradable polyester resin may be 1.1 dl / g or more. For example, the intrinsic viscosity (IV) of the biodegradable polyester resin may be 1.15 dl / g or more, 1.23 dl / g or more, 1.3 dl / g or more, 1.4 dl / g or more, 1.45 dl / g or more, 1.5 dl / g or more, 1.55 dl / g or more, or 1.62 dl / g or more. [Method for producing biodegradable polyester resin] Another method for producing a biodegradable polyester resin according to a specific embodiment involves mixing and pre-treating a diol and an aromatic dicarboxylic acid to obtain a slurry, subjecting the slurry to a primary esterification reaction, then adding an aliphatic dicarboxylic acid, or a diol and an aliphatic dicarboxylic acid, and subjecting them to a secondary esterification reaction to obtain a prepolymer, and subjecting the prepolymer to a polycondensation reaction to obtain a polymer. The biodegradable polyester resin contains a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue. The biodegradable polyester resin has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in an X-ray diffraction spectrum (XRD), and the crystal size of the biodegradable polyester resin according to Formula 1 is 50 Å to 80 Å.

[0091] First, a diol and an aromatic dicarboxylic acid are mixed and pre-treated to obtain a slurry.

[0092] The diol may include, as a diol component, 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof. Specifically, the diol may include 1,4-butanediol, 1,2-ethanediol, or a derivative thereof, and may include 1,4-butanediol or a derivative thereof. When the diol includes 1,4-butanediol as a diol component, particularly when the diol consists only of 1,4-butanediol, it may be more advantageous in terms of improving biodegradability, mechanical properties such as tensile strength, and heat resistance. Also, the diol may include a biomass-based diol component.

[0093] For example, as the diol component, the diol may contain 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof in an amount of 95 mol% or more. For example, based on the total number of moles of the diol component, the diol may contain 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof in an amount of 97 mol% or more, 98 mol% or more, 99 mol% or more, or 100 mol%.

[0094] Further, the dicarboxylic acid may contain an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid as the dicarboxylic acid components. Specifically, the aromatic dicarboxylic acid may include terephthalic acid, dimethyl terephthalate, or a derivative thereof, and the aliphatic dicarboxylic acid may include adipic acid, succinic acid, sebacic acid, or a derivative thereof.

[0095] The dicarboxylic acid may contain the aromatic dicarboxylic acid in an amount of 30 mol% or more based on the total number of moles of the dicarboxylic acid components. For example, the content of the aromatic dicarboxylic acid is 32 mol% or more, 36 mol% or more, 42 mol% or more, or 46 mol% or more based on the total number of moles of the dicarboxylic acid components, and may be 30 mol% to 65 mol%, 33 mol% to 62 mol%, 35 mol% to 60 mol%, 38 mol% to 52 mol%, or 42 mol% to 50 mol%.

[0096] The dicarboxylic acid may contain the aliphatic dicarboxylic acid in an amount of 35 mol% or more based on the total number of moles of the dicarboxylic acid components. For example, the content of the aliphatic dicarboxylic acid is 38 mol% or more, 45 mol% or more, 52 mol% or more, or 54 mol% or more based on the total number of moles of the dicarboxylic acid components, and may be 35 mol% to 70 mol%, 38 mol% to 67 mol%, 40 mol% to 65 mol%, 48 mol% to 62 mol%, or 50 mol% to 58 mol%.

[0097] In the pretreatment, the diol may be added to the aromatic dicarboxylic acid in an amount of 1.15 to 1.8, 1.15 to 1.6, or 1.2 to 1.5.

[0098] By controlling the contents of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid within the above ranges, in particular, by controlling the content of the aliphatic dicarboxylic acid within the above range, crystallinity and thermal stability can be ensured, sufficient oriented crystals can be induced by a sufficient crystallization rate, and biodegradability and dimensional stability can be further improved.

[0099] According to one implementation example, by mixing and pre-treating the diol and the aromatic dicarboxylic acid to form a slurry, not only can the diol component and the aromatic dicarboxylic acid react uniformly, but it is also effective in accelerating the rate of the esterification reaction, so the reaction efficiency can be enhanced.

[0100] In particular, when the aromatic dicarboxylic acid has complete crystallinity and is in powder form, such as terephthalic acid, its solubility in the diol is very low, so a uniform reaction may be difficult to occur. Therefore, the pre-treatment step of forming the slurry can play a very important role in enhancing the reaction efficiency of the biodegradable polyester resin having excellent physical properties according to the implementation example.

[0101] Also, by performing the pre-treatment, it is possible to prevent the diol from reacting with the aliphatic dicarboxylic acid in advance in an esterification reaction, so it may be further facilitated to control the number and ratio of the first repeating unit and the second repeating unit.

[0102] On the other hand, in the pre-treatment, since the structure and physical properties of the biodegradable polyester resin may change depending on the particle size and its standard deviation, particle size distribution, pre-treatment reaction conditions, etc. of the aromatic dicarboxylic acid, it is very important to control them.

[0103] According to one implementation example, the aromatic dicarboxylic acid may include terephthalic acid. The description regarding the average particle size (D50) of the terephthalic acid and its standard deviation is as described above.

[0104] Specifically, by pretreating terephthalic acid having an average particle size (D50) of 15 μm to 400 μm and a standard deviation of 100 or less together with the diol, a slurry without phase separation can be produced, and the crystallinity and thermal stability can be further improved.

[0105] According to another embodiment, the aromatic dicarboxylic acid may include dimethyl terephthalate. Different from the terephthalic acid, the dimethyl terephthalate has a melting point of about 142° C., so after being converted to a molten state at 170° C. and then mixed with the diol, it may be more preferable in terms of the esterification reaction rate and reaction efficiency.

[0106] The pretreatment can be performed by charging the diol and the aromatic dicarboxylic acid into a slurry stirrer (tank). Since it is very important to control the stirring force until the mixture of the diol and the aromatic dicarboxylic acid is slurried in the pretreatment, process conditions such as the number and shape of the stirring blades of the stirrer, and the pretreatment temperature and stirring speed are very important.

[0107] Specifically, the slurry stirrer may have an anchor type at the bottommost part. More specifically, the height to the stirrer may be 20 mm or more, and it may be provided with two or more rotating blades. When the slurry stirrer has such a structure, the efficiency of slurrying can be further improved.

[0108] For example, the slurry stirrer has a height to the stirrer of 20 mm or more, and the space between the reactor and the bottommost part of the stirrer is almost in contact. In this case, the efficiency of slurrying can be further improved in that a slurry can be obtained without precipitation. If the shape of the slurry stirrer does not satisfy the above conditions, when the diol and the aromatic dicarboxylic acid are initially mixed, the aromatic dicarboxylic acid may settle to the bottom and phase separation may occur.

[0109] Further, the pretreatment can be performed by stirring a mixture of the diol and the aromatic dicarboxylic acid at 25°C to 100°C and at 50 rpm to 500 rpm for 10 minutes or more. For example, the pretreatment can be performed at a temperature of 25°C to 85°C, 28°C to 60°C, 30°C to 55°C, or 26°C to 50°C, at a stirring speed of 65 rpm to 400 rpm, 70 rpm to 320 rpm, 80 rpm to 300 rpm, 95 rpm to 260 rpm, 100 rpm to 200 rpm, or 120 rpm to 180 rpm, for 10 minutes or more, 15 minutes or more, 25 minutes or more, 30 minutes or more, 10 minutes to 200 minutes, 15 minutes to 160 minutes, 20 minutes to 120 minutes, 22 minutes to 100 minutes, or 26 minutes to 65 minutes.

[0110] By satisfying the temperature, stirring speed, and time of the pretreatment process within the above ranges, a uniform slurry without phase separation can be obtained more efficiently, which may be more preferable in terms of the esterification reaction rate and reaction efficiency.

[0111] Thereafter, after subjecting the slurry to a primary esterification reaction, an aliphatic dicarboxylic acid, or a diol and an aliphatic dicarboxylic acid are added to carry out a secondary esterification reaction to obtain a prepolymer.

[0112] Specifically, after charging the slurry into a reactor to carry out a primary esterification reaction, an aliphatic dicarboxylic acid, or a diol and an aliphatic dicarboxylic acid are added to carry out a secondary esterification reaction to obtain a prepolymer.

[0113] The prepolymer is produced by a two-stage esterification reaction including a primary esterification reaction and a secondary esterification reaction, which can improve the reaction stability and reaction uniformity compared with the case of performing a one-stage esterification reaction, and can further facilitate the control of the number and ratio of the first repeating unit and the second repeating unit.

[0114] The primary esterification reaction can be carried out at 190°C to 260°C, 200°C to 245°C, 205°C to 235°C, or 215°C to 225°C for 1 hour to 4 hours, 1.5 hours to 3.5 hours, or 2.5 hours to 3 hours.

[0115] The secondary esterification reaction can be carried out at 160°C to 240°C, 170°C to 230°C, 185°C to 225°C, or 210°C to 220°C for 0.5 hour to 3 hours, 1 hour to 2.5 hours, or 1.5 hours to 2.2 hours.

[0116] Also, in the secondary esterification reaction, the diol can be added in an amount of 1.12 to 1.6 or 1.2 to 1.4 with respect to the aliphatic dicarboxylic acid.

[0117] According to another embodiment, the method for producing the biodegradable polyester resin may further include a step of adding a cellulose additive. The description of the cellulose additive is as described above.

[0118] Specifically, the cellulose additive can be added to the primary esterification reaction product or the secondary esterification reaction product. More specifically, the cellulose additive can be added before the primary esterification reaction, or after the primary esterification reaction and before the secondary esterification reaction.

[0119] At this time, when the cellulose additive is added before the secondary esterification reaction compared to when it is added before the primary esterification reaction, the binding force of the nanocellulose can be improved, so the biodegradability, thermal properties, and durability can be further improved.

[0120] The content of the cellulose-based additive to be added may be 3000 ppm or less based on the total weight of the primary esterification reactant or the secondary esterification reactant. For example, based on the total weight of the primary esterification reactant or the secondary esterification reactant, it may be added at 3000 ppm or less, 2400 ppm or less, 2300 ppm or less, 2000 ppm or less, 1800 ppm or less, 1500 ppm or less, 1250 ppm or less, or 1000 ppm or less, and a cellulose-based additive of 100 ppm or more, 130 ppm or more, 190 ppm or more, 230 ppm or more, 260 ppm or more, 300 ppm or more, 330 ppm or more, 380 ppm or more, 420 ppm or more, or 450 ppm or more may be additionally added.

[0121] Also, the cellulose-based additive may be added at a temperature of 20°C to 230°C, 25°C to 220°C, 150°C to 225°C, 185°C to 225°C, or 210°C to 220°C. It may be preferable in that it can improve mechanical properties such as tensile strength and durability by satisfying the above range for the addition temperature of the cellulose-based additive.

[0122] Furthermore, the cellulose-based additive is added at a rate of 2 Kg / min to 10 Kg / min, 2.5 Kg / min to 9.5 Kg / min, or 3 Kg / min to 8 Kg / min, which can prevent aggregation and improve strength, impact strength, and heat resistance, and can maintain an appropriate process speed. If the addition rate is less than the above range, additional processes are required, the speed is too slow and the efficiency is reduced. If the addition rate exceeds the above range, re-aggregation may occur and the tensile strength and heat resistance may decrease.

[0123] Also, before the stage of performing the esterification reaction and / or before the stage of performing the following polycondensation reaction, a titanium-based catalyst or a germanium-based catalyst may be further added.

[0124] For example, before the step of performing the primary and secondary esterification reactions and / or before the step of performing the polycondensation reaction, one or more catalysts selected from the group consisting of titanium isopropoxide, tetrapropyl titanate, tetrabutyl titanate, tetraisopropyl titanate, germanium oxide, germanium methoxide, germanium ethoxide, tetramethylgermanium, tetraethylgermanium, and germanium sulfide may be further added.

[0125] At this time, the content of the added catalyst may be 100 ppm to 1000 ppm. For example, the content of the added catalyst may be 100 ppm to 650 ppm, 120 ppm to 500 ppm, or 150 ppm to 350 ppm based on the total weight of the diol, aromatic dicarboxylic acid, and aliphatic dicarboxylic acid. Further, when the catalyst is added to both the esterification reaction and the polycondensation reaction, the total content of the added catalyst may be 1200 ppm or less, 950 ppm or less, or 880 ppm or less.

[0126] Also, before the step of performing the esterification reaction and / or before the step of performing the following polycondensation reaction, an amine-based high-temperature heat stabilizer such as tetraethylenepentamine; one or more phosphorus-based stabilizers selected from the group consisting of phosphoric acid, phosphorous acid, polyphosphoric acid, trimethyl phosphate, triethyl phosphate, triethyl phosphonoacetate, trimethylphosphine, and triphenylphosphine; or a branching agent such as glycerol may be further added. For example, the stabilizer may be added before the step of performing the secondary esterification reaction or before the step of performing the following polycondensation reaction, and the branching agent may be added before the step of performing the primary esterification reaction and / or before the step of performing the secondary esterification reaction.

[0127] The content of the stabilizer or branching agent can be 3000 ppm or less. For example, the content of the phosphorus-based stabilizer or branching agent can be 10 ppm to 3000 ppm, 20 ppm to 2000 ppm, 25 ppm to 1500 ppm, or 30 ppm to 1000 ppm based on the total weight of the diol, aromatic dicarboxylic acid, and aliphatic dicarboxylic acid. By the content of the phosphorus-based stabilizer satisfying the above range, it can be advantageous in that the deterioration of the polymer due to high temperature during the reaction process can be controlled, and the number of end groups of the polymer can be reduced or the color can be improved.

[0128] Also, before the step of performing the following polycondensation reaction, one or more selected from the group consisting of additives such as silica, potassium, or magnesium, and color correctors such as cobalt acetate can be additionally added. Specifically, after the esterification reaction is completed, the additive and / or color corrector can be added for stabilization, and then the polycondensation reaction can proceed.

[0129] The number average molecular weight of the prepolymer can be 800 g / mol to 30000 g / mol. For example, the number average molecular weight of the prepolymer can be 850 g / mol to 20000 g / mol, 880 g / mol to 18000 g / mol, 900 g / mol to 10000 g / mol, 920 g / mol to 8000 g / mol, 940 g / mol to 4500 g / mol, or 960 g / mol to 2000 g / mol.

[0130] The number average molecular weight can be measured using gel permeation chromatography (GPC). Specifically, although there are various items such as Mn, Mw, and Mp in the data obtained by gel permeation chromatography, among them, the molecular weight can be measured based on the number average molecular weight (Mn).

[0131] Thereafter, the prepolymer is subjected to a polycondensation reaction to obtain a polymer.

[0132] Specifically, the polycondensation reaction can be carried out in two steps. For example, after subjecting the prepolymer to a primary polycondensation reaction, it can be introduced into a disc ring type reactor and subjected to a secondary polycondensation reaction to obtain a polymer. At this time, the secondary polycondensation can proceed while removing the vapor of 1,4-butanediol and by-products.

[0133] The primary polycondensation reaction can be carried out at a temperature of 255°C or lower, 250°C or lower, 245°C or lower, 240°C or lower, 215°C to 255°C, 225°C to 245°C, or 230°C to 242°C, and a pressure of 1 torr to 100 torr, 2 torr to 65 torr, 5 torr to 40 torr, 7 torr to 25 torr, or 8 torr to 15 torr for 0.5 hour to 3 hours, 1 hour to 2.5 hours, or 1.5 hours to 2 hours.

[0134] Also, the secondary polycondensation reaction can be carried out at a temperature of 210°C to 250°C, 215°C to 245°C, or 225°C to 240°C while reducing the pressure to 1 torr or lower, 0.8 torr or lower, or 0.5 torr or lower for 0.5 hour or more, 0.8 hour or more, or 1 hour or more.

[0135] By satisfying the temperature, pressure, and time conditions of the primary polycondensation and secondary polycondensation within the respective ranges, the mechanical properties and heat resistance can be improved.

[0136] According to another embodiment, an inorganic filler slurry can be further introduced before the step of carrying out the polycondensation reaction in the method for producing the biodegradable polyester resin.

[0137] Specifically, the inorganic filler slurry can be introduced into the primary polycondensation reaction product or the secondary polycondensation reaction product. More specifically, the inorganic filler slurry can be introduced before the primary polycondensation reaction, or after the primary polycondensation reaction and before the secondary polycondensation reaction.

[0138] At this time, the content of the inorganic filler slurry to be introduced can be 10,000 ppm or less based on the total weight of the reactants for the polycondensation reaction. For example, the content of the inorganic filler slurry can be 8,500 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 3,500 ppm or less, or 2,500 ppm or less based on the total weight of the reactants for the polycondensation reaction, and can be 100 ppm to 10,000 ppm, 500 ppm to 8,000 ppm, 800 ppm to 5,500 ppm, or 1,500 ppm to 3,000 ppm.

[0139] The inorganic filler slurry can be a slurry containing the inorganic filler. Specifically, the inorganic filler slurry is a mixture of the diol component and the inorganic filler, and more specifically, the inorganic filler slurry means a slurry in which the inorganic filler is dispersed in the diol component. The description of the inorganic filler is as described above.

[0140] The content of the inorganic filler can be 3% by weight to 30% by weight based on the total weight of the inorganic filler slurry. For example, the content of the inorganic filler can be 5% by weight to 28% by weight, 7% by weight to 23% by weight, 9% by weight to 16% by weight, or 9.5% by weight to 12% by weight based on the total weight of the inorganic filler slurry.

[0141] The number average molecular weight of the polymer can be 40,000 g / mol or more. For example, the number average molecular weight of the polymer can be 43,000 g / mol or more, 48,000 g / mol or more, or 55,000 g / mol or more, and can be 40,000 g / mol to 70,000 g / mol, 42,000 g / mol to 65,000 g / mol, 45,000 g / mol to 58,000 g / mol, or 48,000 g / mol to 55,000 g / mol. By satisfying the above range of the number average molecular weight of the polymer, the mechanical properties, processability, and productivity can be further improved.

[0142] According to another embodiment, biodegradable polyester resin pellets can be produced from the polymer.

[0143] Specifically, after cooling the polymer at 70°C or lower, 50°C or lower, 45°C or lower, or 25°C or lower, the cooled polymer can be cut under water or cut into strands to produce pellets.

[0144] The cutting step may be carried out without limitation using any pellet cutter used in the art, and the pellets can have various shapes.

[0145] [Molded article] An embodiment can provide a molded article made from the biodegradable polyester resin.

[0146] Specifically, the molded article is produced by molding a composition containing the biodegradable polyester resin by methods known in the art such as compounding, extrusion and stretching, extrusion and blowing, injection, etc. The molded article can be an injection molded article, an extrusion molded article, a thin film molded article, or a blow molded article, but is not limited thereto.

[0147] For example, the molded article can be in the form of a film or sheet that can be used for agricultural mulching films, disposable gloves, disposable films, disposable bags, food packaging materials, garbage bags, etc., fibrous that can be used for fabrics, knitted fabrics, non-woven fabrics, ropes, etc., and container-shaped that can be used as food packaging containers such as lunch boxes. Further, the molded article can also be molded articles of various shapes such as disposable straws, cutlery (spoons), trays, forks, etc.

[0148] Furthermore, the biodegradable polyester resin can be utilized in various fields requiring heat resistance, mechanical properties, dimensional stability, and moldability, such as packaging materials like disposable bags and food containers, and automotive interior materials, and can exhibit excellent properties.

[0149] [Biodegradable polyester film] Another biodegradable polyester film according to another embodiment contains a biodegradable polyester resin, wherein the biodegradable polyester resin contains a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue, and the biodegradable polyester resin has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in an X-ray diffraction spectrum (XRD), and the crystal size of the biodegradable polyester resin according to Formula 1 is 50 Å to 80 Å.

[0150] The description of the biodegradable polyester resin is as described above.

[0151] Specifically, the biodegradable polyester film contains the biodegradable polyester resin, and more specifically, by being manufactured using the biodegradable polyester resin, it has excellent mechanical properties, dimensional stability, and moldability.

[0152] The tensile strength of the biodegradable polyester film can be 30 MPa or more. For example, the tensile strength of the biodegradable polyester film can be 30 MPa or more, 32 MPa or more, 33 MPa or more, or 35 MPa or more, and can be 70 MPa or less, 65 MPa or less, 55 MPa or less, 45 MPa or less, or 43 MPa or less. The tensile strength can be the tensile strength of a biodegradable polyester film manufactured at an elongation rate of 300% or 800%.

[0153] Also, when the biodegradable polyester film is heat-treated at 50 °C for 5 minutes, the heat shrinkage rate in the main shrinkage direction can be 50% or less. For example, when the biodegradable polyester film is heat-treated at 50 °C for 5 minutes, the heat shrinkage rate in the main shrinkage direction can be 50% or less, 45% or less, 42% or less, 40% or less, 33% or less, 28% or less, 25% or less, or 20% or less. The heat shrinkage rate can be the heat shrinkage rate of a biodegradable polyester film manufactured at an elongation rate of 300% or 800%.

[0154] By satisfying the above ranges for the tensile strength and the heat shrinkage rate, the biodegradable polyester film has excellent thermal stability and dimensional stability, and thus can exhibit excellent properties even when applied as a packaging material for products that require heat resistance.

[0155] The main shrinkage direction can be the length direction (MD) or the width direction (TD). Specifically, the main shrinkage direction can be the length direction (MD).

[0156] Also, the biodegradable polyester film may have a peak at a diffraction angle (2θ) of 18.0 ± 0.3° with respect to the X-ray diffraction spectrum (XRD). By having a peak at a diffraction angle (2θ) of 18.0 ± 0.3° with respect to the X-ray diffraction spectrum (XRD), when a heavy object is applied to a molded product using the film, almost no breakage occurs during the additional elongation process. Therefore, when the biodegradable polyester film is applied to products that require heat resistance, mechanical properties, dimensional stability, and moldability, such as disposable bags, food containers, and automotive interior materials, it can have excellent stability.

[0157] Also, the biodegradable polyester film may satisfy the following formula 2. [Formula 2] |Hmc1 - Hmc2| ≥ 0.1 In the above formula 2, Hmc1 is the heat of crystal melting (J / g) of the biodegradable polyester resin measured by a differential scanning calorimeter (Differential Scanning Calorimetry, DSC), Hmc2 is the heat of crystal melting (J / g) of the biodegradable polyester film produced at an elongation rate of 800% measured by a differential scanning calorimeter.

[0158] The explanation regarding the heat of crystal melting and its measurement method is as described above. For example, the Hmc2 may be the one measured by a differential scanning calorimeter for the biodegradable polyester film (3 mg) produced at an elongation rate of 800%.

[0159] For example, the value according to Formula 2 may be 0.1 or more, 0.15 or more, 0.2 or more, 0.23 or more, or 0.3 or more. By the value according to Formula 2 satisfying the above range, the biodegradable polyester film may have excellent thermal stability and dimensional stability.

[0160] Also, the thickness of the biodegradable polyester film may be 5 μm to 200 μm. For example, the thickness of the biodegradable polyester film may be 5 μm to 160 μm, 6 μm to 130 μm, 8 μm to 115 μm, 10 μm to 100 μm, 12 μm to 90 μm, or 13 μm to 85 μm.

[0161] The biodegradability of the biodegradable polyester film may be 90% or more. For example, the biodegradability of the biodegradable polyester film may be 91% or more, 92% or more, 93% or more, 94% or more, or 95% or more.

[0162] [Method for manufacturing biodegradable polyester film] Also, the method for manufacturing a biodegradable polyester film according to another embodiment may include the step of manufacturing a sheet from biodegradable polyester resin pellets. The description of the biodegradable polyester resin pellets is as described above.

[0163] Specifically, a sheet may be manufactured using hot pressing. For example, prepare two Teflon sheets, place a stainless steel (SUS) frame (12 cm in length and 12 cm in width) on one Teflon sheet, then put the biodegradable polyester resin pellets into the stainless steel (SUS) frame and cover it with the other Teflon sheet. Then, after holding the hot press at a temperature of 200 °C and a pressure of 10 Mpa for 3 minutes, remove the frame and immediately immerse it in water at 20 °C and cool it for 30 seconds to manufacture a biodegradable polyester sheet.

[0164] The thickness of the biodegradable polyester sheet can be 5 μm to 500 μm. For example, the thickness of the biodegradable polyester sheet can be 5 μm to 500 μm, 15 μm to 450 μm, 30 μm to 380 μm, 50 μm to 350 μm, 55 μm to 400 μm, 60 μm to 300 μm, 70 μm to 420 μm, 85 μm to 360 μm, or 100 μm to 330 μm.

[0165] Thereafter, the biodegradable polyester sheet can be stretched to produce a biodegradable polyester film.

[0166] Specifically, the stretching can be performed by uniaxial stretching in the first direction or the second direction perpendicular to the first direction, or by biaxial stretching or simultaneous biaxial stretching in the first direction and the second direction perpendicular to the first direction.

[0167] In this specification, the first direction can be the width direction (TD) or the length direction (MD). Specifically, the first direction can be the length direction (MD), and the second direction perpendicular to the first direction can be the width direction (TD).

[0168] Also, after stretching the biodegradable polyester sheet at an elongation rate of 100% to 900% (1 to 9 times) in the first direction, it can be stretched at an elongation rate of 100% to 900% (1 to 9 times) in the second direction perpendicular to the first direction to produce a biodegradable polyester film. Or, the biodegradable polyester sheet can be stretched at an elongation rate of 100% to 900% (1 to 9 times) in the first direction to produce a biodegradable polyester film.

[0169] For example, the elongation rate can be 110% to 900%, 150% to 880%, 220% to 850%, 260% to 830%, 300% to 800%, 110% to 650%, 200% to 350%, 250% to 320%, 600% to 900%, 720% to 860%, or 780% to 820%.

[0170] Also, the stretching can be performed at 45°C or higher. For example, the stretching temperature can be 48°C or higher, 50°C or higher, or 60°C or higher.

[0171] Moreover, the manufacturing method of the biodegradable polyester film according to another embodiment may include the steps of drying and melt-extruding the biodegradable polyester resin pellets. The description of the biodegradable polyester resin pellets is as described above.

[0172] The drying can be performed at 60°C to 100°C for 2 hours to 12 hours. Specifically, the drying can be performed at 62°C to 80°C, 63°C to 75°C, or 65°C to 70°C for 3 hours to 10 hours or 4 hours to 7 hours. By satisfying the above range for the drying process conditions of the pellets, the quality of the manufactured biodegradable polyester film can be further improved.

[0173] The melt-extrusion can be performed at 140°C or higher. For example, the melt-extrusion can be performed at 155°C or higher, 170°C or higher, 190°C or higher, or 210°C or higher.

[0174] Specifically, the melt-extrusion process can be performed using a blown film process.

[0175] (Example) The above content will be further described in detail by the following examples. However, the following examples are only for illustrating the present invention, and the scope of the examples is not limited to these only.

[0176] [Manufacture of Biodegradable Polyester Resin Pellets] (Example 1-1) (1) Step of pretreating the mixture of diol and aromatic dicarboxylic acid As a diol component, 46 mol% of 1,4-butanediol (1,4-BDO) and 46 mol% of terephthalic acid (TPA) as an aromatic dicarboxylic acid were charged into a slurry tank (the bottom of the slurry tank is of the anchor type, the height to the upper stirrer is 30 mm, and three rotating blades are provided) in an amount of 1.4 of diol with respect to the dicarboxylic acid. After that, it was stirred at 40 °C and 150 rpm for 30 minutes to produce a slurry without phase separation.

[0177] At this time, the average particle size (D50) of the terephthalic acid (TPA) was 130 μm, and the standard deviation with respect to the average particle size (D50) was 25.

[0178] (2) Step of producing a prepolymer The slurry produced in the step (1) was charged into a reactor through a supply line, and 160 ppm of tetrabutyl titanate (Tyzor (registered trademark), Dupont), which is a titanium-based catalyst, was charged thereto. After that, the temperature was raised to 220 °C, and a primary esterification reaction was carried out for 2.5 hours until 95% of the by-product water was discharged.

[0179] Thereafter, 54 mol% of 1,4-butanediol (1,4-BDO) and 54 mol% of adipic acid (AA) were charged into the primary esterification reaction product in an amount of 1.2 of diol with respect to the dicarboxylic acid, and 200 ppm of tetrabutyl titanate (Tyzor, Dupont), which is a titanium-based catalyst, was further charged. After that, a secondary esterification reaction was carried out at 210 °C for 2 hours until 95% of the by-product water was discharged to produce a prepolymer having a number average molecular weight of 1000 g / mol.

[0180] (3) Step of producing a polymer 100 ppm of triethyl phosphate as a heat stabilizer and 300 ppm of tetrabutyl titanate (Tyzor, Dupont), which is a titanium-based catalyst, were charged into the prepolymer produced in the step (2), and after stabilizing for 10 minutes, a primary polycondensation reaction was carried out at 240 °C and 10 torr for 2 hours.

[0181] Thereafter, the primary polycondensation reaction product was charged into a disc ring type reactor, and a secondary polycondensation reaction was carried out for 3 hours while reducing the pressure to 0.5 torr at 240 °C to produce a polymer having a number average molecular weight of 50,000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4-butanediol and by-products.

[0182] Thereafter, the polymer was immersed in water and cut by an underwater cutter to produce biodegradable polyester resin pellets.

[0183] (Example 1-2) In step (2), biodegradable polyester resin pellets were produced in the same manner as in Example 1-1, except that 640 ppm of cellulose nanocrystal (CNC having -SO3Na as a terminal group, average particle size: 160 nm, particle size deviation: 25%, manufactured by CelluForce), a cellulose-based additive, was further added to the primary esterification reaction product.

[0184] (Example 1-3) In step (3), biodegradable polyester resin pellets were produced in the same manner as in Example 1-1, except that 5000 ppm of an inorganic filler slurry was further added to the prepolymer. At this time, the amount of the inorganic filler slurry charged into the reactor through a 500 mesh filter pipe was set and charged within 10 minutes.

[0185] The inorganic filler slurry was produced by mixing 90% by weight of 1,4-butanediol (1,4-BDO) and 10% by weight of titanium dioxide (manufactured by DONW TMC, average particle size (D50): 0.5 μm, specific surface area: 110 m 2 / g).

[0186] (Example 1-4) In step (1), biodegradable polyester resin pellets were produced in the same manner as in Example 1-1, except that terephthalic acid (TPA) having an average particle size (D50) of 150 μm and a standard deviation with respect to the average particle size (D50) of 30 was used.

[0187] (Example 1-5) Biodegradable polyester resin pellets were produced in the same manner as in Example 1-3, except that an inorganic filler slurry was used at 2000 ppm.

[0188] (Comparative Example 1-1) (1) Step of pretreating a mixture of diol and aromatic dicarboxylic acid 50 mol% of 1,4-butanediol (1,4-BDO) as the diol component and 50 mol% of terephthalic acid (TPA) as the dicarboxylic acid component were charged into a slurry tank (the bottom of the slurry tank is of the anchor type, the height to the upper stirrer is 30 mm, and it is equipped with three rotating blades) in an amount of 1.1 of diol with respect to the dicarboxylic acid, and then stirred at 60 °C and 150 rpm for 30 minutes to produce a slurry without phase separation.

[0189] At this time, the average particle size (D50) of the terephthalic acid (TPA) was 500 μm, and the standard deviation with respect to the average particle size (D50) was 120.

[0190] (2) Step of producing a prepolymer The slurry produced in step (1) was charged into a reactor through a supply line, and 300 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), which is a titanium-based catalyst, was added thereto. Then, the temperature was raised to 220 °C, and a primary esterification reaction was carried out for 2 hours until 95% of the by-product water was discharged.

[0191] Thereafter, 50 mol% of 1,4-butanediol (1,4-BDO) and 50 mol% of adipic acid (AA) were added to the primary esterification reaction product in an amount of 1.0 of diol relative to the dicarboxylic acid. After further adding 200 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), which is a titanium-based catalyst, a secondary esterification reaction was carried out at 220 °C for 1.5 hours until 95% of the by-product water was discharged, to produce a prepolymer having a number average molecular weight of 800 g / mol.

[0192] (3) Step of producing a polymer To the prepolymer produced in the step (2) were added 50 ppm of triethyl phosphate, which is a heat stabilizer, and 300 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), which is a titanium-based catalyst. After stabilizing for 10 minutes, a primary polycondensation reaction was carried out at 260 °C and 100 torr for 1 hour.

[0193] Thereafter, the primary polycondensation reaction product was charged into a disk-ring type reactor, and a secondary polycondensation reaction was carried out at 265 °C and 0.5 torr for 2 hours to produce a polymer having a number average molecular weight of 25,000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4-butanediol and by-products.

[0194] Thereafter, the polymer was immersed in water and cut by a underwater cutter to produce biodegradable polyester resin pellets.

[0195] (Comparative Example 1-2) A slurry was not produced in step (1). In step (2), biodegradable polyester resin pellets were produced in the same manner as in Comparative Example 1-1, except that 50 mol% of 1,4-butanediol (1,4-BDO) as a diol component and 50 mol% of terephthalic acid (TPA) as a dicarboxylic acid component were introduced into the reactor via a supply line in an amount of 1.1 of diol relative to the dicarboxylic acid.

[0196] (Comparative Example 1-3) In step (1), biodegradable polyester resin pellets were produced in the same manner as in Comparative Example 1-1, except that terephthalic acid (TPA) was used at 39 mol% and in step (2), adipic acid (AA) was used at 61 mol%.

[0197] (Experimental Example) (Experimental Example 1-1: Diffraction Angle (2θ), Full Width at Half Maximum (FWHM), and Crystal Size) For the biodegradable polyester resin pellets produced in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-3, the diffraction angle, full width at half maximum, and crystal size were measured using a wide angle X-ray scattering device (Wide angle X-ray scattering, WAXD) (Ultima IV, Rigaku).

[0198] Specifically, the resin pellets were cut into spheres with a width of 1.5 cm, and the wavelength was collided with them at a diffraction angle (2θ) of 10° to 35°, and the wavelength diffracted at a scan speed of 5° / min was measured. At this time, the diffraction angle (2θ) at which the peak of the diffracted wavelength appeared was measured, and the full width at half maximum (FWHM) at the diffraction angle (2θ) was calculated.

[0199] Also, the crystal size was calculated according to the following formula 1. [Formula 1] JPEG2025522302000005.jpg1264In the above formula 1, λ is the wavelength (nm) in the X-ray diffraction spectrum (XRD), β is the full width at half maximum (FWHM) at the diffraction angle (2θ), θ is half of the diffraction angle (2θ), The X-ray diffraction spectrum (XRD) was measured at a diffraction angle (2θ) of 10° to 35° at a scan speed of 5° / min.

[0200] (Experimental Example 1-2: Crystallization Temperature and Heat of Crystal Melting) For the biodegradable polyester resin pellets produced in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-3, the crystallization temperature and heat of crystal melting were measured using a differential scanning calorimeter.

[0201] Specifically, the 3 mg of the pellets were cut into a cylindrical shape (thickness: 0.5 mm, circular diameter: 4 mm), placed in an aluminum pan, and after heating from 40°C to 180°C at a rate of 10°C / min using a differential scanning calorimeter, the exothermic peak measured while cooling to -50°C at a rate of 10°C / min was the crystallization temperature (Tc), and the integral value at the crystallization temperature (Tc) was calculated as the heat of crystal melting (Hmc1).

[0202] [Table 1]

[0203] [Table 2]

[0204] As shown in Table 1 and Table 2 above, the biodegradable polyester resin pellets of Examples 1-1 to 1-5 had peaks at specific diffraction angles and satisfied the specific range of crystal size according to Formula 1 compared to the resin pellets of Comparative Examples 1-1 to 1-3, showing excellent results in the heat of crystal melting.

[0205] Specifically, the biodegradable polyester resin pellets of Examples 1-1 to 1-5 were produced by pretreating a mixture of diol and aromatic dicarboxylic acid and subjecting it to primary and secondary esterification reactions under specific conditions. In particular, by being produced with an aromatic dicarboxylic acid having a specific average particle size (D50) and a standard deviation with respect thereto, the crystallinity was adjusted, and both the crystal size and the heat of crystal melting were excellent.

[0206] [Production of Biodegradable Polyester Film] (Example 2-1) (1) Production of Biodegradable Polyester Sheet Two Teflon sheets were prepared, and a stainless steel (SUS) frame (12 cm in length and 12 cm in width) was placed on one of the Teflon sheets. After putting 7 g of the biodegradable polyester resin pellets produced in Example 1-1 into the stainless steel (SUS) frame, it was covered with another Teflon sheet and placed at the center of a hot press (25 cm in length and 25 cm in width, WL1600SA, manufactured by WITHLAB). After holding the hot press at a temperature of 200 °C and a pressure of 10 Mpa for 3 minutes, the frame was removed and immediately immersed in water at 20 °C for 30 seconds for cooling to produce a biodegradable polyester sheet having a thickness of 300 μm.

[0207] (2) Production of biodegradable polyester film The biodegradable polyester sheet produced in the above step (1) was stretched at 45 °C in the MD direction at elongation rates of 300% or 800% respectively to produce a biodegradable polyester film.

[0208] (Examples 2-2 to 2-5 and Comparative Examples 2-1 to 2-3) A biodegradable polyester film was produced in the same manner as in Example 2-1, except that the biodegradable polyester resin pellets produced in Examples 1-2 to 1-5 and Comparative Examples 1-1 to 1-3 were used. However, in the case of Example 2-2, biodegradable polyester films stretched at 100% or 600% respectively were additionally produced.

[0209] (Experimental Example) (Experimental Example 2-1: Moving value of diffraction angle (2θ)) Regarding the biodegradable polyester films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3, the moving value of the diffraction angle (2θ) at 17.3° was measured using a wide-angle X-ray scattering device (WAXD) (Ultima IV, manufactured by Rigaku). At this time, in the same manner as in Experimental Example 1-1, the wavelength was collided at a diffraction angle (2θ) of 10° to 35°, and the wavelength diffracted at a scan speed of 5° / min was measured.

[0210] (Experimental Example 2-2: Crystallization temperature and heat of crystal melting) For the biodegradable polyester films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3, the crystallization temperature and the heat of crystal fusion were measured using a differential scanning calorimeter.

[0211] Specifically, 3 mg of the film was cut into a cylindrical shape (thickness: 0.5 mm, circular diameter: 4 mm), placed in an aluminum pan, and heated from 40°C to 180°C at a rate of 10°C / min using a differential scanning calorimeter. Then, while cooling to -50°C at a rate of 10°C / min, the exothermic peak measured was the crystallization temperature (Tc), and the integral value at the crystallization temperature (Tc) was calculated as the heat of crystal fusion (Hmc2).

[0212] Also, the value of the following formula was calculated according to the measurement results. |Hmc1 - Hmc2| In the above formula, Hmc1 is the heat of crystal fusion (J / g) of the biodegradable polyester resin measured by a differential scanning calorimeter (DSC), Hmc2 is the heat of crystal fusion (J / g) of the biodegradable polyester film produced at an elongation rate of 800% measured by a differential scanning calorimeter.

[0213] (Experimental Example 2-3: Tensile Strength) For the biodegradable polyester films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3, test pieces were produced according to the ASTM D638 Type V standard, and after experimenting at a tensile speed of 100 mm / min using a universal testing machine (UTM 4206-001) from INSTRON, the tensile strength (MPa) was measured using a program built into the equipment.

[0214] (Experimental Example 2-4: Heat Shrinkage Rate) The biodegradable polyester films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3 were cut into test pieces with a length of 10 cm and a width of 150 mm. After that, they were heat-treated in a hot air oven at 80 °C for 5 minutes, and the heat shrinkage rate (%) in the length direction (MD direction) was calculated according to the following formula A. At this time, five test pieces were produced for each, and the heat shrinkage rate (%) was measured, and the average value was calculated.

[0215] [Formula A] JPEG2025522302000008.jpg16128In the above formula A, x1 is the length of the film before heat treatment, x2 is the length of the film that has shrunk after heat treatment.

[0216] (Experimental Example 2-5: Degree of biodegradability) Regarding the biodegradable polyester films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3, the amount of carbon dioxide generated was measured based on KS M3100-1 to measure the degree of biodegradability. Specifically, an inoculum source container containing only compost produced in a compost plant was prepared, and a test container was prepared in which 5% by weight of the film was added to the compost based on the dry weight of the compost. Then, it was cultured for 180 days under the conditions of a temperature of 58 ± 2 °C, a water content of 50%, and an oxygen concentration of 6% or more. The carbon dioxide generated in each container was collected and titrated with an aqueous solution of phenolphthalein to measure the amount of carbon dioxide generated in each container. The degree of biodegradability was calculated according to the following formula B using the measured amount of carbon dioxide generated.

[0217] [Formula B] JPEG2025522302000009.jpg13142

[0218] [Table 3]

[0219] [Table 4]

[0220] As shown in Table 3 and Table 4 above, the biodegradable polyester films of Examples 2-1 to 2-5 showed excellent results in terms of heat of crystal fusion, tensile strength, heat shrinkage rate, and biodegradability characteristics compared to the films of Comparative Examples 2-1 to 2-3.

[0221] Specifically, the biodegradable polyester films of Examples 2-1 to 2-5 were produced from the biodegradable polyester resin pellets of Examples 1-1 to 1-5, so they had excellent crystallinity, did not have a decrease in biodegradability, had high tensile strength, and low heat shrinkage rate. Therefore, even when applying heavy objects to molded products using the biodegradable polyester film, almost no breakage occurs during the additional elongation process. So, when applied to products that require heat resistance, mechanical properties, dimensional stability, and moldability, such as packaging materials like disposable bags and food containers, and automotive interior materials, they were excellent in stability.

[0222] Figure 1 shows the X-ray diffraction analysis (XRD) results of the biodegradable polyester film of Example 2-2. Specifically, it shows the X-ray diffraction analysis results when the biodegradable polyester film of Example 2-2 was produced at an elongation rate of 0% (before stretching, that is, the biodegradable polyester resin pellets of Example 1-2), and when stretched at 100%, 300%, 600%, and 800%. It was confirmed that the diffraction angle (2θ) at which peaks appear moves according to the elongation rate. More specifically, when comparing the diffraction angles at which peaks appear at an elongation rate of 0% and 800%, it was confirmed that 17.3° shifted to 18.2°.

[0223] Thus, the biodegradable polyester films of Examples 2-1 to 2-5 satisfied the value according to the above formula 2 being 0.1 or more, so the crystal structure changed and the crystallinity improved.

[0224] On the other hand, since the films of Comparative Examples 2-1 to 2-3 were produced from the pellets of Comparative Examples 1-1 to 1-3, they had low crystallinity, resulting in low tensile strength and high heat shrinkage rate. Therefore, when applying heavy molded products using the films, breakage easily occurs during the additional stretching process, and when applied to products that require heat resistance, mechanical properties, dimensional stability, and moldability, such as packaging materials like disposable bags and food containers, and automotive interior materials, the stability was very low.

Claims

1. A biodegradable polyester resin containing a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue, having peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in an X-ray diffraction spectrum (XRD), and having a crystal size according to the following formula 1 of 50 Å to 80 Å: [Formula 1] In the above formula 1, λ is the wavelength (nm) in the X-ray diffraction spectrum (XRD), β is the full width at half maximum (FWHM) at the diffraction angle (2θ), θ is half of the diffraction angle (2θ), and the X-ray diffraction spectrum (XRD) was measured at a scan rate of 5° / min at diffraction angles (2θ) of 10° to 35°.

2. The biodegradable polyester resin according to Claim 1, wherein the full width at half maximum (FWHM) at each diffraction angle (2θ) is less than 1.0° / 2θ.

3. The crystallization temperature (Tc) of the biodegradable polyester resin measured by a differential scanning calorimeter (DSC) is 35°C to 65°C, and the heat of crystal fusion (Hmc １ ), is 19.1 J / g or more. The biodegradable polyester resin according to claim 1.

4. The aromatic dicarboxylic acid contains terephthalic acid, and the terephthalic acid has a number-average particle size (D50) measured by a particle size analyzer Microtrac S3500 in a particle size distribution (PSD) of 10 μm to 400 μm, and a standard deviation with respect to the number-average particle size (D50) of 100 or less. The biodegradable polyester resin according to Claim 1.

5. The biodegradable polyester resin according to Claim 1, wherein the biodegradable polyester resin contains a cellulose-based additive.

6. The biodegradable polyester resin contains an inorganic filler including at least one selected from the group consisting of titanium dioxide (TiO ２ ), silicon dioxide (SiO ２ ), calcium carbonate (CaCo ３ ), talc, aluminum oxide (Al ２ O ３ ), calcium oxide (CaO), and potassium oxide (K ２ O). For the inorganic filler, the number-based average particle diameter (D50) measured by a particle size analyzer Microtrac S3500 in the particle size distribution (PSD) is 100 µm or less, and the specific surface area is 100 m ２ / g or more, The biodegradable polyester resin according to claim 1.

7. The biodegradable polyester resin according to Claim 1, further containing one or more resins selected from the group consisting of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate terephthalate (PBST), polybutylene succinate adipate (PBSA), polybutylene adipate (PBA), and polycaprolactone (PCL).

8. Each of the diol residues contains a first diol residue and a second diol residue containing a residue of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof, and the biodegradable polyester resin contains a first repeating unit containing the first diol residue and the aromatic dicarboxylic acid residue, and a second repeating unit containing the second diol residue and the aliphatic dicarboxylic acid residue. The biodegradable polyester resin according to claim 1, comprising the first repeating unit and the second repeating unit in the form of a block copolymer.

9. Mixing and pretreating a diol and an aromatic dicarboxylic acid to obtain a slurry; After subjecting the slurry to a primary esterification reaction, adding an aliphatic dicarboxylic acid, or a diol and an aliphatic dicarboxylic acid, and subjecting it to a secondary esterification reaction to obtain a prepolymer; A method for producing a biodegradable polyester resin, comprising subjecting the prepolymer to a polycondensation reaction to obtain a polymer, wherein the biodegradable polyester resin contains a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue, wherein the biodegradable polyester resin has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in an X-ray diffraction spectrum (XRD), A method for producing a biodegradable polyester resin, wherein the crystal size of the biodegradable polyester resin according to the following formula 1 is 50 Å to 80 Å: [Formula 1] In the formula 1, λ is the wavelength (nm) in an X-ray diffraction spectrum (XRD), β is the full width at half maximum (FWHM) at the diffraction angle (2θ), θ is half of the diffraction angle (2θ), The X-ray diffraction spectrum (XRD) was measured at a scan rate of 5° / min at a diffraction angle (2θ) of 10° to 35°.

10. The method for producing a biodegradable polyester resin according to claim 9, further comprising, before the step of subjecting to the polycondensation reaction, adding an inorganic filler slurry at 10000 ppm or less based on the total weight of the reactants for the polycondensation reaction.

11. The method for producing a biodegradable polyester resin according to claim 9, wherein the pretreatment is performed by stirring a mixture of the diol and the aromatic dicarboxylic acid at 25°C to 100°C at 50 rpm to 500 rpm for 10 minutes or more.

12. A biodegradable polyester film containing a biodegradable polyester resin, wherein the biodegradable polyester resin contains a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue, wherein the biodegradable polyester resin has peaks at diffraction angles (2θ) of 17.3 ± 0.3°, 20.4 ± 0.3°, 23.3 ± 0.3°, and 25.0 ± 0.3° in an X-ray diffraction spectrum (XRD), A biodegradable polyester film in which the crystal size of the biodegradable polyester resin according to the following formula 1 is 50 Å to 80 Å: [Formula 1] In the above formula 1, λ is the wavelength (nm) in the X-ray diffraction spectrum (XRD), β is the full width at half maximum (FWHM) at the diffraction angle (2θ), θ is half of the diffraction angle (2θ), The X-ray diffraction spectrum (XRD) was measured at a scan rate of 5° / min at a diffraction angle (2θ) of 10° to 35°.

13. The tensile strength of the biodegradable polyester film is 30 MPa or more, When the biodegradable polyester film is heat-treated at 50 °C for 5 minutes, the heat shrinkage rate in the main shrinkage direction is 50% or less, The biodegradable polyester film according to claim 12, which has a peak at a diffraction angle (2θ) of 18.0 ± 0.3° with respect to the X-ray diffraction spectrum (XRD).

14. The biodegradable polyester film according to claim 12, which satisfies the following formula 2: [Formula 2] | Hmc １ -Hmc ２ |≥0.1 In the above formula 2, Hmc １ is the heat of crystal fusion (J / g) of the biodegradable polyester resin measured by a differential scanning calorimeter (DSC), Hmc ２ is the heat of crystal melting (J / g) measured with a differential scanning calorimeter for the biodegradable polyester film produced at an elongation rate of 800%.

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