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

Abstract

The present disclosure relates to a biodegradable polyester resin, a method for producing the same, and a biodegradable polyester film containing the same. The biodegradable polyester resin can improve any of biodegradability, mechanical properties such as tensile strength and impact strength, and heat resistance by satisfying specific ranges of polydispersity index (PDI) and weight loss rate. Further, when a film is produced using the biodegradable polyester resin, defects such as fume, bubbles, and fisheyes do not occur, so that processability and productivity can be improved.

Description

Technical Field

[0001] The present 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, polymer materials are widely used to manufacture various products such as films, fibers, packaging materials, bottles, and containers because they are inexpensive and have excellent properties such as processability. 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 naturally.

[0003] In order to overcome such limitations of polymers, research on biodegradable polymers that are decomposed within a shorter time has been actively conducted. As biodegradable polymers, polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxy alkanoate (PHA), polycaprolactone (PCL), etc. are used. However, compared to non-degradable resins such as polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP), their mechanical properties such as tensile strength and impact strength are low, their melting points are low, and their heat resistance is weak, so the process is difficult and the productivity is low. Therefore, there is an actual need for research on biodegradable polymer resins that can improve both processability and productivity while not reducing biodegradability and mechanical properties and having excellent heat resistance.

[0004] As an example, Patent Document 1 discloses a biodegradable plastic composition in which polypropylene carbonate (PPC) is mixed with a composition containing PLA, PBS, etc. to improve durability. However, such a method by blending has limitations in improving durability, heat resistance, etc.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, the embodiments provide a biodegradable polyester resin that is excellent in biodegradability, mechanical properties such as tensile strength and impact strength, and heat resistance, and can also improve processing suitability and productivity, 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 embodiment includes a first repeating unit containing a first diol residue and an aromatic dicarboxylic acid residue, and a second repeating unit containing a second diol residue and an aliphatic dicarboxylic acid residue, has a polydispersity index (PDI) of less than 2.0, and the weight loss rate (%) under specific temperature (T °C) conditions according to the following formula 1 is ΔW T When it is, ΔW 220 is 1.3% or less.

[0008] [Formula 1] JPEG2025518776000001.jpg1284 In the above formula 1, W is the weight (mg) of the biodegradable polyester resin whose moisture content is adjusted to 100 ppm, WT is the weight (mg) measured with a thermogravimetric analyzer by retaining the biodegradable polyester resin with the adjusted water content at T °C for 60 minutes.

[0009] A method for producing a biodegradable polyester resin according to another embodiment includes a step of pretreating a mixture of a diol and a dicarboxylic acid to produce a slurry, a step of subjecting the slurry to an esterification reaction to produce a prepolymer, and a step of subjecting the prepolymer to a polycondensation reaction to produce a polymer. The biodegradable polyester resin includes a first repeating unit containing a first diol residue and an aromatic dicarboxylic acid residue, and a second repeating unit containing a second diol residue and an aliphatic dicarboxylic acid residue. The polydispersity index (PDI) of the biodegradable polyester resin is less than 2.0. When the weight loss rate (%) under the specific temperature (T °C) condition according to Formula 1 is ΔW T then the ΔW of the biodegradable polyester resin 220 is 1.3% or less.

[0010] Another biodegradable polyester film according to an embodiment includes a biodegradable polyester resin. The biodegradable polyester resin includes a first repeating unit containing a first diol residue and an aromatic dicarboxylic acid residue, and a second repeating unit containing a second diol residue and an aliphatic dicarboxylic acid residue. The polydispersity index (PDI) of the biodegradable polyester resin is less than 2.0. When the weight loss rate (%) under the specific temperature (T °C) condition according to Formula 1 is ΔW T then the ΔW of the biodegradable polyester resin 220 is 1.3% or less.

Advantages of the Invention

[0011] The biodegradable polyester resin according to the embodiment has a polydispersity index (PDI) of less than 2.0 and satisfies a weight loss rate (ΔW 220 ) of 1.3% or less according to Formula 1, thereby improving all of biodegradability, mechanical properties such as tensile strength and impact strength, and heat resistance.

[0012] In addition, when a film is manufactured using the biodegradable polyester resin, defects such as fume, bubbles, and fisheye do not occur, so that the processability and productivity can be improved.

[0013] Furthermore, the biodegradable polyester resin can be utilized in various fields that require heat resistance and moldability, such as medical instruments and containers, disposable food containers, etc., and can exhibit excellent properties.

Mode for Carrying Out the Invention

[0014] Hereinafter, the invention will be described in detail by way of implementation examples. The implementation examples are not limited to the content disclosed below, and can be modified into various forms as long as the gist of the invention is not changed.

[0015] In this specification, when a certain part says that a certain component "includes", this means that, unless otherwise stated, it does not exclude other components, but 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 stated.

[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 used only for the purpose of distinguishing one component from another.

[0018] Polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), polycaprolactone (PCL), etc., which are widely used as biodegradable polymers, have lower mechanical properties such as tensile strength and impact strength compared to non-degradable resins such as polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP). Their melting points are low and their heat resistance is weak, making the process difficult and the productivity low.

[0019] Specifically, in order to manufacture molded products such as films using resins, a compounding process, an extrusion and stretching process, an extrusion and blow process, an injection process, etc. are carried out. However, in the case of biodegradable resins, when heat of 180 °C or higher is applied in such manufacturing processes, degradation of the polymer can easily occur. As a result, oligomers may vaporize to generate fumes, or oligomers may precipitate white, resulting in a decrease in quality and a possible decrease in mechanical properties such as tensile strength and impact strength.

[0020] In particular, in the compounding process, a twin screw is generally used to enhance the kneading property. However, due to the shear stress between the screw element used at this time and the biodegradable resin, thermal decomposition of the resin can be accelerated. Therefore, the change value of the intrinsic viscosity (IV drop), which is the absolute value of the difference between the intrinsic viscosity of the resin and the intrinsic viscosity of the film produced therefrom, may increase, and the generation of fumes may be maximized, and yellowing or browning may occur.

[0021] In addition, in the extrusion and stretching processes, oligomers may accumulate on the casting drum and scatter, causing wire breakage by an electrostatic application method and halting production. Deteriorated polymers may generate as bubbles or voids, resulting in a decline in quality and productivity. In the extrusion and blow processes, oligomers may act as a defect in bubble formation, leading to a decrease in bubble stability, such as bubble rupture. Further, in the injection process, oligomers may cause fish eyes or fusion between film surfaces in the injection molded product.

[0022] The biodegradable polyester resin according to the implementation example includes a first repeating unit containing a first diol residue and an aromatic dicarboxylic acid residue, and a second repeating unit containing a second diol residue and an aliphatic dicarboxylic acid residue, has a polydispersity index (PDI) of less than 2.0, and satisfies a weight loss rate (ΔW 220 ) of 1.3% or less according to Formula 1, thereby improving biodegradability, mechanical properties such as tensile strength and impact strength, and heat resistance. Further, when a film is manufactured using the biodegradable polyester resin, defects such as fumes, bubbles, and fish eyes do not occur, improving processability and productivity, and enabling the provision of a film with excellent quality.

[0023] Specifically, the biodegradable polyester resin according to the implementation example has excellent biodegradability, mechanical properties such as tensile strength and impact strength, and heat resistance without a decrease in biodegradability. Therefore, even when intensive mixing is performed using a twin screw in the compounding process, the change value of the intrinsic viscosity (IV drop), which is the absolute value of the difference between the intrinsic viscosity of the resin and the intrinsic viscosity of the film produced therefrom, is low, and almost no fumes are generated, and almost no yellowing or browning occurs. Further, even when an extremely small amount of an electrostatic additive is added in the extrusion and stretching processes, no wire breakage occurs, bubbles are well formed in the blow process, and the bubble stability is high, and almost no fish eyes or fusion between film surfaces occurs in the injection process.

[0024] [Biodegradable Polyester Resin] The biodegradable polyester resin according to one implementation example includes 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, has a polydispersity index (PDI) of less than 2.0, and has a weight loss rate (%) under specific temperature (T °C) conditions according to the following formula 1 as ΔW T When, ΔW 220 is 1.3% or less.

[0025] [Formula 1] In the above formula 1, W is the weight (mg) of the biodegradable polyester resin whose moisture content is adjusted to 100 ppm, W T is the weight (mg) measured by a thermogravimetric analyzer after retaining the biodegradable polyester resin with the adjusted moisture content at T °C for 60 minutes.

[0026] According to one implementation example, the biodegradable polyester resin includes a diol residue, an aromatic dicarboxylic acid residue, and an aliphatic dicarboxylic acid residue.

[0027] 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 biodegradable polyester resin can improve biodegradability and mechanical physical properties.

[0028] 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.

[0029] In addition, 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.

[0030] According to one implementation example, the aromatic dicarboxylic acid may include terephthalic acid. Specifically, the terephthalic acid has a number-based 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 average particle size (D50) may be 100 or less.

[0031] 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 size and standard deviation with respect to it satisfy the above range.

[0032] 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 135 μm.

[0033] Also, 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.

[0034] By the average particle size of the terephthalic acid and the standard deviation thereof each satisfying the above ranges, the solubility in the diol can be improved, which may be more advantageous in terms of the esterification reaction rate in subsequent steps. Specifically, by the average particle size of the terephthalic acid and the standard deviation thereof each 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 may be more preferable in terms of reaction efficiency.

[0035] Also, 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 slows down, and the uniformity of the reaction may also decrease.

[0036] According to another embodiment, the aromatic dicarboxylic acid may contain dimethyl terephthalate. Specifically, the dimethyl terephthalate can be in a similar range to the average particle size (D50) of the terephthalic acid and the standard deviation thereof when measured in a molten state or in a particulate state.

[0037] According to another embodiment, the aliphatic dicarboxylic acid may include adipic acid. Specifically, in the particle size distribution (PSD), the number-based average particle diameter (D50) measured by a particle size analyzer Microtrac S3500 of the adipic acid may be 50 μm to 500 μm, and the standard deviation with respect to the average particle diameter (D50) may be 100 or less.

[0038] For example, the average particle diameter (D50) of the adipic acid may be 60 μm to 480 μm, 80 μm to 460 μm, 120 μm to 450 μm, 180 μm to 420 μm, 200 μm to 390 μm, 220 μm to 360 μm, 235 μm to 350 μm, or 260 μm to 330 μm.

[0039] Also, the standard deviation with respect to the average particle diameter (D50) of the adipic acid may be 90 or less, 70 or less, 55 or less, 40 or less, or 30 or less, and may be 5 to 90, 5 to 65, 10 to 60, 12 to 45, 15 to 40, or 16 to 30.

[0040] By satisfying the average particle diameter of adipic acid and the standard deviation with respect to it within the respective ranges, the dispersibility can be further improved, and it may be more advantageous in terms of the esterification reaction rate in subsequent processes. Specifically, by satisfying the average particle diameter of adipic acid and the standard deviation with respect to it within the respective ranges, the physical properties are not deteriorated, and the esterification reaction time can be shortened by 1.5 times or more, so it may be more preferable in terms of reaction efficiency.

[0041] Specifically, the first repeating unit may include a residue of 1,4-butanediol or its derivative and a residue of terephthalic acid or its derivative. Alternatively, the first repeating unit may include a residue of 1,4-butanediol or its derivative and a residue of dimethyl terephthalate or its derivative.

[0042] Further, the second repeating unit may include a residue of 1,4 - butanediol or its derivative and a residue of adipic acid or its derivative. Alternatively, the second repeating unit may include a residue of 1,4 - butanediol or its derivative and a residue of succinic acid or its derivative.

[0043] 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.

[0044] Specifically, 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.

[0045] Generally, polyester resins, for example, polybutylene adipate terephthalate (PBAT) - based resins are excellent in flexibility but weak in 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.

[0046] Specifically, when the number of the second repeating unit is the same as or more than the number of the first repeating unit, excellent durability and heat resistance can be maintained during a specific period, the biodegradability does not decrease, and after the use is completed, biodegradation can be sufficiently effective.

[0047] Also, the number (X) of the first repeating units can be 200 to 800, 210 to 700, 220 to 550, 225 to 500, 230 to 460, 235 to 420, 240 to 400, 245 to 360, or 245 to 320. Also, the number (Y) of the second repeating units can be 150 to 600, 160 to 530, 180 to 480, 190 to 460, 200 to 420, 215 to 400, 220 to 385, 235 to 350, or 240 to 315.

[0048] By the number of the first repeating units and the number of the second repeating units each satisfying the above range, any of biodegradability, mechanical properties, heat resistance, dimensional stability, moldability, and productivity can be improved.

[0049] In particular, since the second repeating unit containing the second diol residue and the aliphatic dicarboxylic acid residue is composed of a linear chain and contains an aliphatic dicarboxylic acid residue that can affect the adhesion properties, 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.

[0050] Also, the ratio (X / Y) of the number (X) of the first repeating units to 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 to 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, 0.83 to 1.85, 0.85 to 1.6, 0.85 to 1.3, or 0.85 to 1.1.

[0051] By the ratio (X / Y) of the number (X) of the first repeating units to the number (Y) of the second repeating units satisfying the above range, mechanical properties such as tensile strength can be improved. In particular, when the blow molding process is performed using the biodegradable polyester resin, the bubble stability can be improved, such as the bubbles having a uniform shape and not bursting. Also, when the injection molding process is performed using the biodegradable polyester resin, the generation of fisheyes and fusion between the film surfaces can be effectively prevented, so the quality and processability can be improved.

[0052] 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.

[0053] Specifically, when the first repeating unit and the second repeating unit are contained in the form of a block copolymer, when orientation crystals are formed in the stretching process using the biodegradable polyester resin, it is advantageous for generating microcrystals, and since steric hindrance does not occur, crystallization can be achieved sufficiently effectively. Therefore, a biodegradable polyester resin containing the first repeating unit and the second repeating unit in the form of a block copolymer can have orientation crystals induced well by stretching and form a dense crystal structure, so that the mechanical properties such as the tensile strength of molded products, especially films, and dimensional stability manufactured using this can be maximized.

[0054] Also, the biodegradable polyester resin may contain nanocellulose. By the biodegradable polyester resin containing nanocellulose, biodegradability, crystallinity, thermal stability, mechanical properties such as tensile strength, and dimensional stability can be further improved.

[0055] Specifically, the nanocellulose may 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.

[0056] The average particle size of the nanocellulose is 100 nm or more, and the particle size deviation can be 32% or less. For example, the average particle size of the nanocellulose is 100 nm or more, 120 nm or more, or 140 nm or more, and is 100 nm to 1500 nm, 115 nm to 1200 nm, 120 nm to 950 nm, 135 nm to 700 nm, 140 nm to 550 nm, and the particle size deviation of the nanocellulose can be 31% or less, 30% or less, 29.5% or less, 26% or less, 25% or less, 23% or less, or 20% or less.

[0057] The average particle size and particle size deviation of the nanocellulose can be measured with a nanoparticle analyzer (ex. Zetasizer Nano ZS). Specifically, for the nanocellulose, 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.

[0058] Also, the biodegradable polyester resin may contain the nanocellulose at 3000 ppm or less. For example, the content of the nanocellulose is 2500 ppm or less, 2000 ppm or less, 1200 ppm or less, 1000 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 can be 100 ppm to 3000 ppm, 150 ppm to 2400 ppm, 180 ppm to 1900 ppm, 250 ppm to 1500 ppm, 400 ppm to 1250 ppm, or 450 ppm to 1000 ppm.

[0059] Also, the nanocellulose may be one that has been pretreated with a bead mill, ultrasonic treatment, stirring, or hydrophobization. Specifically, the nanocellulose may be one in which the water-dispersed nanocellulose has been pretreated with a bead mill, ultrasonic treatment, stirring, or hydrophobization.

[0060] First, the bead mill pretreatment can be performed by 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, reduces uneven wear of the machine, reduces wear of the beads, and is easier to maintain, but is not limited thereto.

[0061] 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.

[0062] 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 nanocellulose can be further improved. If the bead diameter exceeds the above range, the average particle size and particle size deviation of nanocellulose can be increased, and thus the dispersibility may decrease.

[0063] Also, it may be preferable to use beads having a higher specific gravity than that of nanocellulose in the bead mill pretreatment in that sufficient energy can be transmitted. For example, the beads are one or more selected from the group consisting of zirconium, zircon, zirconia, quartz, and aluminum oxide having a higher specific gravity than that of water-dispersed nanocellulose, and zirconium beads having a specific gravity 4 times or more higher than that of the water-dispersed nanocellulose may be preferable, but are not limited thereto.

[0064] The bead mill pretreatment can be performed at a linear velocity of 20 m / sec or less with the chamber filled with beads at 80% or more. 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 at a linear velocity of 18 m / sec or less, 17 m / sec or less, or 16 m / sec or less. By satisfying the filling rate and the linear velocity within the above ranges, the effect of the bead mill pretreatment, i.e., the improvement in dispersibility, can be maximized.

[0065] Also, the ultrasonic pretreatment is a method of physically crushing or pulverizing nanoparticles by waves generated by emitting ultrasonic waves of 20 kHz into the solution.

[0066] Specifically, the ultrasonic pretreatment can be performed for a time of less than 30 minutes with an energy amount of 30000 J or less. For example, the ultrasonic pretreatment can be performed with an energy amount of 30000 J or less, 26000 J or less, 24500 J or less, 22000 J or less, 19500 J or less, 16500 J or less, or 16000 J or less, and 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 energy amount and the implementation time of the ultrasonic pretreatment within the above ranges, the effect of the ultrasonic pretreatment, i.e., the improvement in dispersibility, can be maximized.

[0067] According to one implementation example, the nanocellulose can be pretreated by a bead mill or ultrasonically. Or, the nanocellulose can be pretreated by both a bead mill and ultrasonically. At this time, it may be preferable that the ultrasonic pretreatment is performed after the bead mill pretreatment in terms of preventing re-aggregation and improving dispersibility.

[0068] When the nanocellulose, specifically, the water-dispersed nanocellulose, is pretreated with a bead mill or ultrasonication, the dispersibility can be maximized, so that 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 ultrasonication-pretreated water-dispersed nanocellulose than in the non-bead mill-pretreated or non-ultrasonication-pretreated water-dispersed nanocellulose. Therefore, when the nanocellulose is additionally bead mill-pretreated or ultrasonication-pretreated, the dispersion stability can be further improved.

[0069] Also, the stirring pretreatment can be performed at 10,000 rpm or less for 1 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 to 90 minutes, 30 to 85 minutes, 45 to 70 minutes, or 50 to 65 minutes.

[0070] Also, the hydrophobization 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).

[0071] Specifically, by the hydrophobization treatment method, the dimensional stability can be further improved by substituting a part of the hydroxyl groups of the nanocellulose with hydrophobic groups having a reduced affinity for water. 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.

[0072] The polydispersity index (PDI) of the biodegradable polyester resin according to the implementation example is less than 2.0. For example, the polydispersity index of the biodegradable polyester resin can be less than 2.0, 1.95 or less, or 1.9 or less.

[0073] By adjusting the polydispersity index to the above range, the heat resistance can be further improved. Specifically, when the polydispersity index exceeds the above range, the heat resistance of the biodegradable polyester resin may decrease and polymer deterioration may easily occur. Therefore, when manufacturing a molded product such as a film using the biodegradable polyester resin, the occurrence rate of polymer deterioration is low in the process, so the processing suitability and productivity can be improved.

[0074] The polydispersity index can be calculated by the following formula A. [Formula A] In the formula A, Mw is the weight average molecular weight (g / mol) of the resin, Mn is the number average molecular weight (g / mol) of the resin.

[0075] The weight average molecular weight and the number average molecular weight can be measured using gel permeation chromatography (GPC).

[0076] According to one implementation example, when the weight loss rate (%) at a specific temperature (T °C) according to the following formula 1 is ΔW T then the ΔW of the biodegradable polyester resin 220 can be 1.3% or less. Note that ΔW T means the weight loss rate (%) under specific temperature (T °C) conditions.

[0077] [Formula 1] In the formula 1, W is the weight (mg) of the biodegradable polyester resin with the moisture content adjusted to 100 ppm, W Tis the weight (mg) measured by a thermogravimetric analyzer after retaining the biodegradable polyester resin with the adjusted water content at T °C for 60 minutes.

[0078] Specifically, the ΔW of the biodegradable polyester resin 220 is 1.3% or less, 1.25% or less, 1.23% or less, 1.2% or less, 1.18% or less, 1.16% or less, 1.15% or less, 1.13% or less, 1.1% or less, 1.05% or less, 1.0% or less, 0.98% or less, or 0.95% or less. ΔW, which is the weight loss rate at 220 °C, a general process temperature for manufacturing molded products such as films using the resin 220 satisfies the above range, whereby the biodegradable polyester resin can have excellent heat resistance.

[0079] Further, the biodegradable polyester resin may satisfy the following formula 2. [Formula 2] |ΔW 240 - ΔW 180 | ≤ 1.5% Specifically, the above ΔW 240 and the above ΔW 180 can be calculated according to the above formula 1, respectively. For example, the above ΔW 240 is the weight loss rate at 240 °C and can be 0.1% to 2.0%, 0.2% to 1.9%, 0.3% to 1.8%, 0.45% to 1.55%, 0.5% to 1.4%, 0.5% to 1.2%, 0.55% to 1.15%, or 0.6% to 1.1%. Also, ΔW 180 is the weight loss rate at 180 °C and can be 0.05% to 0.3%, 0.07% to 0.26%, 0.09% to 0.25%, or 0.1% to 0.25%.

[0080] More specifically, the value according to the above formula 2 is 1.5% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.0% or less, or 0.95% or less, and can be 0.1% to 1.5%, 0.15% to 1.3%, 0.2% to 1.2%, 0.3% to 1.0%, or 0.45% to 0.95%.

[0081] By satisfying the value according to the above formula (2) within the above range, the biodegradable polyester resin can have excellent heat resistance. Specifically, in a wide temperature range of 180°C to 240°C, the smaller the difference in the weight loss rate respectively, the better the heat resistance. As a result, the process conditions can be applied flexibly, so that the processing suitability and productivity can be further improved.

[0082] Also, the number of carboxyl terminal groups of the biodegradable polyester resin can be 50 eq / ton or less. For example, the number of carboxyl terminal groups of the biodegradable polyester resin can 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 terminal groups within the above range, in the process of manufacturing a molded article such as a film using the biodegradable polyester resin, the generation rate of polymer deterioration can be reduced, and both mechanical properties such as tensile strength and heat resistance can be improved.

[0083] Also, the intrinsic viscosity (IV) of the biodegradable polyester resin can be 1.1 dl / g or more. For example, the intrinsic viscosity (IV) of the biodegradable polyester resin can 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] The method for producing a biodegradable polyester resin according to another embodiment includes a step of pretreating a mixture of diol and dicarboxylic acid to produce a slurry, a step of subjecting the slurry to an esterification reaction to produce a prepolymer, and a step of subjecting the prepolymer to a polycondensation reaction to produce a polymer. The biodegradable polyester resin includes a first repeating unit containing a first diol residue and an aromatic dicarboxylic acid residue, and a second repeating unit containing a second diol residue and an aliphatic dicarboxylic acid residue. The polydispersity index (PDI) of the biodegradable polyester resin is less than 2.0, and the weight loss rate (%) under the specific temperature (T°C) condition according to the above formula (1) is ΔWT When it is [specified condition], the ΔW of the biodegradable polyester resin 220 is 1.3% or less.

[0084] First, a mixture of a diol and a dicarboxylic acid is pretreated to produce a slurry.

[0085] The diol may include 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof as a diol component. 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. Further, the diol may include a biomass-based diol component.

[0086] For example, the diol may include a first diol and a second diol as a diol component, and may include 95 mol% or more of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof. For example, based on the total number of moles of the diol component, the diol may include 97 mol% or more, 98 mol% or more, 99 mol% or more, or 100 mol% of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof.

[0087] Further, the dicarboxylic acid may include an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid as a dicarboxylic acid component. 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.

[0088] The dicarboxylic acid may contain 30 mol% or more of an aromatic dicarboxylic acid based on the total number of moles of the dicarboxylic acid component. For example, the content of the aromatic dicarboxylic acid may be 32 mol% or more, 36 mol% or more, 42 mol% or more, 46 mol% or more, or 50 mol% or more based on the total number of moles of the dicarboxylic acid component, and may be 30 mol% to 65 mol%, 33 mol% to 62 mol%, 35 mol% to 60 mol%, 38 mol% to 56 mol%, or 42 mol% to 52 mol%.

[0089] The dicarboxylic acid may contain 35 mol% or more of an aliphatic dicarboxylic acid based on the total number of moles of the dicarboxylic acid component. For example, the content of the aliphatic dicarboxylic acid may be 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 component, and may be 35 mol% to 70 mol%, 38 mol% to 67 mol%, 40 mol% to 65 mol%, 42 mol% to 60 mol%, or 45 mol% to 54 mol%.

[0090] By controlling the contents of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid within the above ranges, particularly 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.

[0091] Also, the step of manufacturing the slurry may be performed by stirring a mixture of the diol and the dicarboxylic acid at 60°C to 100°C at 50 rpm to 200 rpm for 10 minutes or more.

[0092] According to another embodiment, the step of manufacturing the slurry may include a step of pretreating a mixture of the first diol and the aromatic dicarboxylic acid to manufacture a first slurry, and a step of pretreating a mixture of the second diol and the aliphatic dicarboxylic acid to manufacture a second slurry.

[0093] Specifically, by mixing and pre-treating the diol and the dicarboxylic acid to form a slurry, not only can the diol and the dicarboxylic acid react uniformly, but it is also effective in accelerating the rate of the esterification reaction, so the reaction efficiency can be enhanced.

[0094] In particular, when an aromatic dicarboxylic acid such as terephthalic acid has complete crystallinity and is in powder form, its solubility in the diol is very low, so a homogeneous reaction may hardly occur. Therefore, the step of pre-treating to produce the slurry, especially the step of producing the first slurry, can play a very important role in enhancing the reaction efficiency of the biodegradable polyester resin having excellent physical properties according to the embodiments.

[0095] Also, by performing the pre-treatment to produce the first slurry, the diol can be prevented from reacting with the aliphatic dicarboxylic acid first, so it may be easier to control the number and ratio of the first repeating unit and the second repeating unit.

[0096] 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.

[0097] According to one embodiment, the aromatic dicarboxylic acid may include terephthalic acid. The description of the average particle size (D50) of the terephthalic acid and its standard deviation is as described above.

[0098] Specifically, by pre-treating 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 first diol, a slurry without phase separation can be produced, and the crystallinity and thermal stability can be further improved.

[0099] 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. Therefore, after being converted to a molten state at 170°C and then mixed with the first diol, it may be more preferable in terms of the esterification reaction rate and reaction efficiency.

[0100] According to one embodiment, the aliphatic dicarboxylic acid may include adipic acid. The description regarding the particle size (D50) and standard deviation of the adipic acid is as described above.

[0101] Specifically, by pretreating adipic acid having a particle size (D50) of 50 μm to 500 μm and a standard deviation of 100 or less together with the second diol, a slurry without phase separation can be produced, and the crystallinity and thermal stability can be further improved.

[0102] The pretreatment can be performed by charging the diol and the 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 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.

[0103] Specifically, the slurry stirrer may have an anchor type at the bottom, and more specifically, the height to the agitator 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.

[0104] For example, the height of the slurry stirrer to the stirrer is 20 mm or more, and the space between the reactor and the lowermost 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.

[0105] Further, the pretreatment can be 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. 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.

[0106] By satisfying the temperature, stirring speed, and time in the pretreatment step 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.

[0107] Thereafter, the slurry is subjected to an esterification reaction to produce a prepolymer.

[0108] The prepolymer can be produced by a one-step esterification reaction or by a two-step esterification reaction including a primary esterification reaction and a secondary esterification reaction.

[0109] First, when the prepolymer is produced by a one-step esterification reaction, the first and second slurries can be subjected to an esterification reaction at 250°C or lower for 0.5 hour to 5 hours to produce a prepolymer.

[0110] For example, the esterification reaction in the first stage can be carried out at 240 °C or lower, 235 °C or lower, 180 °C to 250 °C, 180 °C to 245 °C, 185 °C to 240 °C, 190 °C to 250 °C, 190 °C to 245 °C, 195 °C to 245 °C, or 200 °C to 240 °C until 95% of the by-product water is discharged. Also, the esterification reaction in the first stage can be carried out for 0.5 hours to 4.5 hours, 0.5 hours to 4 hours, 0.5 hours to 3.5 hours, 0.7 hours to 4.5 hours, 0.7 hours to 4 hours, 0.7 hours to 3.5 hours, or 1 hour to 3.5 hours.

[0111] According to another implementation example, the step of manufacturing the prepolymer may include a step of subjecting the first slurry to a primary esterification reaction at 190 °C to 260 °C, and a step of adding the second slurry to the primary esterification reaction product and subjecting it to a secondary esterification reaction at 160 °C to 240 °C.

[0112] 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 210 °C to 225 °C for 1 hour to 4 hours, 1.5 hours to 3.5 hours, or 2 hours to 3 hours.

[0113] 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 hours to 3 hours, 1 hour to 2.5 hours, or 1.5 hours to 2.2 hours.

[0114] According to another implementation example, the method for manufacturing the biodegradable polyester resin may further include a step of adding nanocellulose. The description of the nanocellulose is as described above.

[0115] Specifically, the nanocellulose can be added to the primary esterification reaction product or the secondary esterification reaction product. More specifically, the nanocellulose can be added before the primary esterification reaction, or after the primary esterification reaction and before the secondary esterification reaction.

[0116] At this time, when the nanocellulose is introduced before the secondary esterification reaction compared to when it is introduced 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.

[0117] Alternatively, the nanocellulose may be introduced during the production of the second slurry. Specifically, in the step of pretreating the mixture of the second diol and the aliphatic dicarboxylic acid to produce a second slurry, it may be introduced together with the second diol and the aliphatic dicarboxylic acid.

[0118] The content of the introduced nanocellulose may be 3000 ppm or less based on the total weight of the primary esterification reactant, the secondary esterification reactant, or the mixture of the second diol and the aliphatic dicarboxylic acid. For example, based on the total weight of the primary esterification reactant, the secondary esterification reactant, or the mixture of the second diol and the aliphatic dicarboxylic acid, it may be introduced 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 additional nanocellulose 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 introduced.

[0119] Also, the nanocellulose may be introduced 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 the mechanical properties such as tensile strength and durability can be improved by the input temperature of the nanocellulose satisfying the above range.

[0120] Furthermore, the nanocellulose is introduced 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 feeding rate is less than the above range, additional processes are required, the speed is too slow and the efficiency decreases. If the feeding rate exceeds the above range, re-aggregation may occur and the tensile strength and heat resistance may decrease.

[0121] Also, before the step of subjecting to the esterification reaction and / or before the step of subjecting to the following polycondensation reaction, a titanium-based catalyst or a germanium-based catalyst may be further introduced.

[0122] For example, before the step of subjecting to the esterification reaction and / or before the step of subjecting to 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, tetramethyl germanium, tetraethyl germanium, and germanium sulfide may be further introduced.

[0123] At this time, the content of the introduced catalyst may be 100 ppm to 1000 ppm. For example, the content of the introduced 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. Also, when the catalyst is introduced into both the esterification reaction and the polycondensation reaction, the total content of the introduced catalyst may be 1200 ppm or less, 950 ppm or less, or 880 ppm or less.

[0124] 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.

[0125] The content of the stabilizer or the branching agent may be 3000 ppm or less. For example, the content of the phosphorus-based stabilizer or the branching agent may 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 satisfying the above range of the content of the phosphorus-based stabilizer, it is possible to control the deterioration of the polymer due to high temperature during the reaction process, and it may be advantageous in that it can reduce the number of end groups of the polymer or improve the color.

[0126] 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 may be further added. Specifically, after the esterification reaction is completed, the additive and / or color corrector may be added and stabilized, and then the polycondensation reaction may be advanced.

[0127] The number average molecular weight of the prepolymer can be 800 g / mol to 30,000 g / mol. For example, the number average molecular weight of the prepolymer can be 850 g / mol to 20,000 g / mol, 880 g / mol to 18,000 g / mol, 900 g / mol to 10,000 g / mol, 920 g / mol to 8,000 g / mol, 940 g / mol to 4,500 g / mol, or 960 g / mol to 2,000 g / mol.

[0128] The number average molecular weight can be measured using gel permeation chromatography (GPC). Specifically, the data obtained by gel permeation chromatography has various items such as Mn, Mw, Mp, etc. Among them, the molecular weight can be measured based on the number average molecular weight (Mn).

[0129] Thereafter, the prepolymer is subjected to a polycondensation reaction to produce a polymer.

[0130] Specifically, the polycondensation reaction can be carried out in two steps. For example, after the prepolymer is subjected to a primary polycondensation reaction, it is charged 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.

[0131] The primary polycondensation reaction is 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, 10 torr to 100 torr, 25 torr to 100 torr, or 30 torr to 85 torr for 0.5 hours to 3 hours, 1 hour to 2.5 hours, or 1.5 hours to 2 hours.

[0132] Also, the secondary polycondensation reaction is 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 hours or more, 0.8 hours or more, or 1 hour or more.

[0133] By satisfying the temperature, pressure, and time conditions of the first and second polycondensations within the respective ranges, the mechanical properties and heat resistance can be improved.

[0134] 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 in the range of 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 number average molecular weight of the polymer within the above range, the mechanical properties, processability, and productivity can be further improved.

[0135] According to another embodiment, biodegradable polyester resin pellets can be produced from the polymer.

[0136] Specifically, after cooling the polymer to 70°C or lower, 50°C or lower, 45°C or lower, or 25°C or lower, the cooled polymer can be cut underwater or by strand cutting to produce pellets.

[0137] The cutting step can be carried out without limitation using a pellet cutter used in the industry, and the pellets can have various shapes.

[0138] [Molded article] An embodiment can provide a molded article produced from the biodegradable polyester resin.

[0139] Specifically, the molded article is produced by molding a composition containing the biodegradable polyester resin by methods known in the industry such as compounding, extrusion and stretching, extrusion and blow, 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.

[0140] For example, the molded article may 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 such as 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.

[0141] Furthermore, 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.

[0142] [Biodegradable Polyester Film] Moreover, the biodegradable polyester film according to another embodiment includes a biodegradable polyester resin, the biodegradable polyester resin includes a first repeating unit containing a first diol residue and an aromatic dicarboxylic acid residue, and a second repeating unit containing a second diol residue and an aliphatic dicarboxylic acid residue, the polydispersity index (PDI) of the biodegradable polyester resin is less than 2.0, and when the weight loss rate (%) under the specific temperature (T °C) condition according to Formula 1 is ΔW T then, ΔW 220 of the biodegradable polyester resin is 1.3% or less.

[0143] The description of the biodegradable polyester resin is as described above.

[0144] Specifically, the biodegradable polyester film contains the biodegradable polyester resin, and more specifically, by being manufactured using the biodegradable polyester resin, it has excellent biodegradability, mechanical properties such as tensile strength and impact strength, and heat resistance.

[0145] The tensile strength of the biodegradable polyester film can be 30 MPa or more. For example, the tensile strength of the biodegradable polyester film is 30 MPa or more, 33 MPa or more, or 35 MPa or more, and can be 30 MPa to 70 MPa, 33 MPa to 65 MPa, 35 MPa to 60 MPa, 35 MPa to 50 MPa, or 35 MPa to 45 MPa.

[0146] Also, the impact absorption energy of the biodegradable polyester film can be 5.0 KJ / m or more. For example, the impact absorption energy of the biodegradable polyester film is 5.0 KJ / m or more, 5.3 KJ / m or more, or 5.4 KJ / m or more, and can be 5.0 KJ / m to 10.0 KJ / m, 5.0 KJ / m to 9.5 KJ / m, 5.0 KJ / m to 8.5 KJ / m, 5.2 KJ / m to 7.3 KJ / m, 5.4 KJ / m to 6.9 KJ / m, or 5.4 KJ / m to 6.7 KJ / m.

[0147] The intrinsic viscosity (IV2) of the biodegradable polyester film can be 0.9 dl / g or more, 0.95 dl / g or more, 1.0 dl / g or more, 1.05 dl / g or more, 1.2 dl / g or more, or 1.23 dl / g or more.

[0148] Also, the biodegradable polyester film can satisfy the following formula 3. [Formula 3] |IV1 - IV2| ≤ 0.2 In the formula 3, IV1 is the intrinsic viscosity (dl / g) of the biodegradable polyester resin, IV2 is the intrinsic viscosity (dl / g) of the biodegradable polyester film.

[0149] For example, the value of the formula 3 is 0.2 or less, 0.19 or less, or 0.18 or less, and can be 0.01 to 0.2, 0.01 to 0.18, 0.02 to 0.18, or 0.04 to 0.18.

[0150] The biodegradable polyester film according to the implementation example has excellent quality with almost no fumes generated in the manufacturing process, when the change value (IV drop) of the intrinsic viscosity, which is the absolute value of the difference between the intrinsic viscosity (IV1) of the resin and the intrinsic viscosity (IV2) of the film produced therefrom, satisfies the above range.

[0151] Also, the thickness of the biodegradable polyester film can be 5 μm to 200 μm. For example, the thickness of the biodegradable polyester film can 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.

[0152] The biodegradability of the biodegradable polyester film can be 90% or more. For example, the biodegradability of the biodegradable polyester film can be 91% or more, 92% or more, 93% or more, 94% or more, or 95% or more.

[0153] [Manufacturing method of biodegradable polyester film] Also, the manufacturing method of the biodegradable polyester film according to another implementation example may include the step of molding a composition or pellet containing a biodegradable polyester resin.

[0154] Specifically, the molding step may be, but is not limited to, the step of melt-extruding and applying electrostatic charge after compounding the composition or pellet, the step of forming a bubble using blowing equipment after compounding, or the step of molding with an injection molding machine after compounding.

[0155] The composition or pellets may contain an electrostatic additive. Specifically, the electrostatic additive is used to reduce peening property and may be a metal acetate such as magnesium acetate, sodium acetate or calcium acetate. The peening property means a phenomenon in the manufacturing process where a composition containing a resin adheres to a roll or the like, resulting in a decrease in physical properties. If such peening property is high, the change value of the intrinsic viscosity (IV drop), which is the absolute value of the difference between the intrinsic viscosity of the resin and the intrinsic viscosity of the film produced therefrom, becomes large, and fumes may be generated. In the extrusion process, the viscosity becomes very low and the fluidity becomes large, resulting in a high thickness deviation, so that the tensile strength, impact strength and heat resistance of the film may decrease.

[0156] The content of the electrostatic additive may be 45 ppm or less based on the total weight of the composition or pellets containing the biodegradable polyester resin. For example, the electrostatic additive may be 45 ppm or less, 40 ppm or less, 35 ppm or less, 30 ppm or less, 25 ppm or less, 20 ppm or less, 18 ppm or less, 15 ppm or less, or 10 ppm or less based on the total weight of the composition or pellets. The content of the electrostatic additive is much lower than that of conventional electrostatic additives. Since the biodegradable polyester resin according to the implementation example is excellent in heat resistance, even if the electrostatic additive is used in such a very small content as described above, wire breakage does not occur during electrostatic application.

[0157] In addition, the composition may contain one or more additives selected from the group consisting of silica, potassium, magnesium, and calcium carbonate. The silica is preferably spherical, but is not limited thereto.

[0158] The content of the additive may be 10 ppm to 1000 ppm based on the total weight of the composition or pellets containing the biodegradable polyester resin. For example, the content of the additive may be 10 ppm to 1000 ppm, 20 ppm to 850 ppm, 25 ppm to 700 ppm, 30 ppm to 600 ppm, 40 ppm to 550 ppm, or 45 ppm to 550 ppm based on the total weight of the composition or pellets.

[0159] Moreover, the method for manufacturing a biodegradable polyester film according to another implementation example may include the steps of drying and melt-extruding biodegradable polyester resin pellets. The description of the biodegradable polyester resin pellets is as described above.

[0160] The drying may be performed at 60°C to 100°C for 2 hours to 12 hours. Specifically, the drying may 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 produced biodegradable polyester film can be further improved.

[0161] The melt-extrusion may be performed at 140°C or higher. For example, the melt-extrusion may be performed at 155°C or higher, 170°C or higher, 190°C or higher, or 210°C or higher.

[0162] (Example) The above content will be further described in more 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 only to these.

[0163] [Manufacture of Biodegradable Polyester Resin Pellets] (Example 1-1) (1) Step of manufacturing a slurry As a diol component, 52 mol% of 1,4 - butanediol (1,4 - BDO) and as an aromatic dicarboxylic acid, 52 mol% of terephthalic acid (TPA) were charged into a first slurry tank (the bottom of the slurry tank is of the anchor type, the height to the upper agitator is 30 mm, and three rotating blades are provided) in an amount of 1.3 of diol with respect to the dicarboxylic acid. After that, it was stirred at 35 °C and 150 rpm for 30 minutes to produce a first slurry without phase separation. 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.

[0164] Also, as a diol component, 48 mol% of 1,4 - butanediol (1,4 - BDO) and as an aliphatic dicarboxylic acid, 48 mol% of adipic acid (AA) were charged into a second slurry tank (the bottom of the slurry tank is of the anchor type, the height to the upper agitator is 30 mm, and three rotating blades are provided) in an amount of 1.3 of diol with respect to the dicarboxylic acid. After charging 1000 ppm of cellulose nanocrystal (CNC with - SO3Na terminal groups, average particle size: 190 nm, particle size deviation: 25%, manufactured by CelluForce) as nanocellulose, it was stirred at 35 °C and 150 rpm for 30 minutes to produce a second slurry without phase separation. The average particle size (D50) of the adipic acid (AA) was 300 μm, and the standard deviation with respect to the average particle size (D50) was 20.

[0165] (2) Step of producing a prepolymer The first and second slurries produced in the step (1) were charged into a reactor via a supply line, and while charging 500 ppm of tetrabutyl titanate (Tyzor (registered trademark), manufactured by Dupont), a titanium - based catalyst, the temperature was raised to 210 °C, and an esterification reaction was carried out for 2.5 hours until 95% of the by - product water was discharged to produce a prepolymer having a number - average molecular weight of 1500 g / mol.

[0166] (3) Step of producing a polymer To the prepolymer produced in the step (2), 200 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), which is a titanium-based catalyst, and 100 ppm of triethyl phosphate, which is a heat stabilizer, were added. After stabilizing for 10 minutes, a primary polycondensation reaction was carried out at 240 °C and 50 torr for 1.5 hours.

[0167] Thereafter, the primary polycondensation reaction product was charged into a disc-ring type reactor, and a secondary polycondensation reaction was carried out while rotating at 240 °C and 0.5 torr for 3 hours to produce a polymer having a number average molecular weight of 60,000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4-butanediol and by-products.

[0168] Thereafter, the polymer was immersed in water and cut by an underwater cutter to produce biodegradable polyester resin pellets.

[0169] (Example 1-2) (1) Step of producing a slurry 53 mol% of 1,4-butanediol (1,4-BDO) as a diol component and 53 mol% of terephthalic acid (TPA) as an aromatic dicarboxylic acid were charged into a first slurry tank (the bottom of the slurry tank is of an 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, the mixture was stirred at 37 °C and 150 rpm for 30 minutes to produce a first slurry without phase separation. 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.

[0170] Also, 47 mol% of 1,4-butanediol (1,4-BDO) as the diol component and 47 mol% of adipic acid (AA) as the aliphatic dicarboxylic acid were charged into the second 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 1.2 of the diol with respect to the dicarboxylic acid. After charging 500 ppm of cellulose nanofiber (CNF, average particle size: 500 nm, particle size deviation: 20%, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as nanocellulose, it was stirred at 37 °C and 150 rpm for 30 minutes to produce a second slurry without phase separation. The average particle diameter (D50) of the adipic acid (AA) was 280 μm, and the standard deviation with respect to the average particle diameter (D50) was 25.

[0171] (2) Step of producing a prepolymer The first and second slurries produced in the step (1) were charged into a reactor through a supply line, and while charging 400 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium-based catalyst, the temperature was raised to 210 °C, and an esterification reaction was carried out for 2.5 hours until 95% of the by-product water was discharged to produce a prepolymer having a number average molecular weight of 2000 g / mol.

[0172] (3) Step of producing a polymer To the prepolymer produced in the step (2), 100 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium-based catalyst, and 100 ppm of triethyl phosphate, a heat stabilizer, were added, and after stabilizing for 10 minutes, a primary polycondensation reaction was carried out at 245 °C and 30 torr for 1.5 hours.

[0173] Thereafter, the primary polycondensation reaction product was charged into a disk ring type reactor, and a secondary polycondensation reaction was carried out while rotating at 240 °C and 0.5 torr for 2.5 hours to produce a polymer having a number average molecular weight of 54000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4-butanediol and by-products.

[0174] Thereafter, the polymer was immersed in water and cut by a cutter in water to produce biodegradable polyester resin pellets.

[0175] (Example 1-3) (1) Step of producing a slurry 50 mol% of 1,4-butanediol (1,4-BDO) as a diol component and 50 mol% of terephthalic acid (TPA) as an aromatic dicarboxylic acid were put into a first slurry tank (the bottom of the slurry tank is of an anchor type, the height to the upper stirrer is 30 mm, and three rotating blades are provided) in an amount of 1.35 of diol with respect to the dicarboxylic acid, and then stirred at 39 °C at 150 rpm for 30 minutes to produce a first slurry without phase separation. 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.

[0176] Also, 50 mol% of 1,4-butanediol (1,4-BDO) as a diol component and 50 mol% of adipic acid (AA) as an aliphatic dicarboxylic acid were put into a second slurry tank (the bottom of the slurry tank is of an anchor type, the height to the upper stirrer is 30 mm, and three rotating blades are provided) in an amount of 1.25 of diol with respect to the dicarboxylic acid, and 700 ppm of cellulose nanocrystal (CNC containing carboxyl group (-COOH), average particle size: 150 nm, particle size deviation: 29%, Blue Goose Refineries) as nanocellulose was added. Then, it was stirred at 39 °C at 150 rpm for 30 minutes to produce a second slurry without phase separation. The average particle size (D50) of the adipic acid (AA) was 320 μm, and the standard deviation with respect to the average particle size (D50) was 30.

[0177] (2) Step of producing a prepolymer The first and second slurries produced in the step (1) are introduced into a reactor via a supply line, and while introducing 300 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), which is a titanium-based catalyst, the temperature is raised to 200 °C, and an esterification reaction is carried out for 3.5 hours until 95% of the by-product water is discharged, to produce a prepolymer having a number average molecular weight of 900 g / mol.

[0178] (3) Step of producing a polymer To the prepolymer produced in the step (2), 100 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), which is a titanium-based catalyst, and 100 ppm of triethyl phosphate, which is a heat stabilizer, are introduced, and after stabilizing for 10 minutes, a primary polycondensation reaction is carried out at 235 °C and 40 torr for 1.5 hours.

[0179] Thereafter, the primary polycondensation reaction product is introduced into a disc-ring type reactor, and a secondary polycondensation reaction is carried out while rotating at 245 °C and 0.5 torr for 2.8 hours to produce a polymer having a number average molecular weight of 55000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4-butanediol and by-products.

[0180] Thereafter, the polymer is immersed in water and cut by a underwater cutter to produce biodegradable polyester resin pellets.

[0181] (Example 1-4) (1) Step of producing a slurry 50 mol% of 1,4-butanediol (1,4-BDO) as a diol component and 50 mol% of terephthalic acid (TPA) as an aromatic dicarboxylic acid are introduced into a first slurry tank (the bottom of the slurry tank is of an anchor type, the height to the upper stirrer is 30 mm, and three rotating blades are provided) in an amount of 1.4 of the diol with respect to the dicarboxylic acid, and then stirred at 40 °C and 150 rpm for 30 minutes to produce a first slurry without phase separation. 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.

[0182] Also, 50 mol% of 1,4 - butanediol (1,4 - BDO) as the diol component and 50 mol% of adipic acid (AA) as the aliphatic dicarboxylic acid were charged into a second 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 1.3 of the diol with respect to the dicarboxylic acid, and stirred at 150 rpm for 30 minutes at 40 °C to produce a second slurry without phase separation. The average particle size (D50) of the adipic acid (AA) was 300 μm, and the standard deviation with respect to the average particle size (D50) was 20.

[0183] (2) Step of producing a prepolymer The first and second slurries produced in the step (1) were charged into a reactor via a supply line, and while charging 300 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium - based catalyst, the temperature was raised to 220 °C, and an esterification reaction was carried out for 2.5 hours until 95% of the by - product water was discharged to produce a prepolymer having a number - average molecular weight of 2000 g / mol.

[0184] (3) Step of producing a polymer To the prepolymer produced in the step (2), 200 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium - based catalyst, and 100 ppm of triethyl phosphate, a heat stabilizer, were added, and after stabilizing for 10 minutes, a primary polycondensation reaction was carried out at 235 °C and 80 torr for 1 hour.

[0185] Thereafter, the primary polycondensation reaction product was charged into a disk - ring type reactor, and a secondary polycondensation reaction was carried out while rotating at 235 °C and 0.5 torr for 2.8 hours to produce a polymer having a number - average molecular weight of 50000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4 - butanediol and by - products.

[0186] Thereafter, the polymer was immersed in water and cut by a cutter in water to produce biodegradable polyester resin pellets.

[0187] (Example 1-5) (1) Step of producing a slurry 50 mol% of 1,4-butanediol (1,4-BDO) as a diol component and 50 mol% of terephthalic acid (TPA) as an aromatic dicarboxylic acid were put into a first slurry tank (the bottom of the slurry tank is of an anchor type, the height to the upper stirrer is 30 mm, and three rotating blades are provided) in an amount of 1.5 of diol with respect to the dicarboxylic acid, and then stirred at 35 °C at 150 rpm for 30 minutes to produce a first slurry without phase separation. 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.

[0188] Also, 50 mol% of 1,4-butanediol (1,4-BDO) as a diol component and 50 mol% of adipic acid (AA) as an aliphatic dicarboxylic acid were put into a second slurry tank (the bottom of the slurry tank is of an anchor type, the height to the upper stirrer is 30 mm, and three rotating blades are provided) in an amount of 1.3 of diol with respect to the dicarboxylic acid, and 1000 ppm of cellulose nanocrystal (CNC with -SO3Na terminal groups, average particle size: 190 nm, particle size deviation: 23%, manufactured by CelluForce) as nanocellulose was put in. Then, it was stirred at 35 °C at 150 rpm for 30 minutes to produce a second slurry without phase separation. The average particle size (D50) of the adipic acid (AA) was 300 μm, and the standard deviation with respect to the average particle size (D50) was 20.

[0189] (2) Step of producing a prepolymer The first slurry produced in the step (1) was put into a reactor through a supply line, and while introducing 200 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium-based catalyst, the temperature was raised to 210 °C, and a primary esterification reaction was carried out for 2 hours until 95% of the by-product water was discharged.

[0190] Thereafter, the second slurry was charged into the primary esterification reaction product, and while charging 150 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium-based catalyst, the temperature was raised to 210° C., and a secondary esterification reaction was carried out for 2 hours until 95% of water as a by-product was discharged, to produce a prepolymer having a number average molecular weight of 1800 g / mol.

[0191] (3) Step of producing a polymer 200 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium-based catalyst, and 100 ppm of triethyl phosphate, a heat stabilizer, 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 100 torr for 0.5 hour.

[0192] Thereafter, the primary polycondensation reaction product was charged into a disc ring type reactor, and a secondary polycondensation reaction was carried out while rotating at 245° C. and 0.5 torr for 3 hours to produce a polymer having a number average molecular weight of 55000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4-butanediol and by-products.

[0193] Thereafter, the polymer was immersed in water and cut by a underwater cutter to produce biodegradable polyester resin pellets.

[0194] (Comparative Example 1-1) (1) Step of producing a slurry The first slurry and the second slurry were produced in the same manner as in Example 1-4.

[0195] (2) Step of producing a prepolymer The first and second slurries produced in the previous step (1) were introduced into a reactor via a supply line, and while introducing 300 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium-based catalyst, the temperature was raised to 240 °C, and an esterification reaction was carried out for 2 hours until 95% of the by-product water was discharged, to produce a prepolymer having a number average molecular weight of 500 g / mol.

[0196] (3) Step of producing a polymer To the prepolymer produced in the previous step (2), 200 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium-based catalyst, and 50 ppm of triethyl phosphate, a heat stabilizer, were added, and after stabilizing for 10 minutes, a primary polycondensation reaction was carried out at 265 °C and 150 torr for 0.5 hour.

[0197] Thereafter, the primary polycondensation reaction product was introduced into a disc-ring type reactor, and a secondary polycondensation reaction was carried out while rotating at 265 °C and 0.5 torr for 1.5 hours to produce a polymer having a number average molecular weight of 38,000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4-butanediol and by-products.

[0198] Thereafter, the polymer was immersed in water and cut by a underwater cutter to produce biodegradable polyester resin pellets.

[0199] (Comparative Example 1-2) (1) Step of producing a slurry 48 mol% of 1,4-butanediol (1,4-BDO) as a diol component and 48 mol% of terephthalic acid (TPA) as an aromatic dicarboxylic acid were introduced into a first slurry tank (the bottom of the slurry tank is of an anchor type, the height up to the upper stirrer is 30 mm, and three rotating blades are provided) in an amount of 1.1 of diol with respect to the dicarboxylic acid, and then stirred at 40 °C and 150 rpm for 30 minutes to produce a first slurry without phase separation. 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.

[0200] Also, 52 mol% of 1,4 - butanediol (1,4 - BDO) as the diol component and 52 mol% of adipic acid (AA) as the aliphatic dicarboxylic acid were charged into a second 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 the diol with respect to the dicarboxylic acid, and stirred at 40 °C and 150 rpm for 30 minutes to produce a second slurry without phase separation. The average particle size (D50) of the adipic acid (AA) was 300 μm, and the standard deviation with respect to the average particle size (D50) was 40.

[0201] (2) Step of producing a prepolymer The first and second slurries produced in the step (1) were charged into a reactor via a supply line, and while charging 1000 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium - based catalyst, the temperature was raised to 240 °C, and an esterification reaction was carried out for 3.5 hours until 95% of the by - product water was discharged to produce a prepolymer having a number - average molecular weight of 600 g / mol.

[0202] (3) Step of producing a polymer To the prepolymer produced in the step (2), 500 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium - based catalyst, and 50 ppm of triethyl phosphate, a heat stabilizer, were added, and after stabilizing for 10 minutes, a primary polycondensation reaction was carried out at 260 °C and 300 torr for 0.5 hour.

[0203] Thereafter, the primary polycondensation reaction product was charged into a disk - ring type reactor, and a secondary polycondensation reaction was carried out while rotating at 260 °C and 0.5 torr for 4.5 hours to produce a polymer having a number - average molecular weight of 70000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4 - butanediol and by - products.

[0204] Thereafter, the polymer was immersed in water and cut by a underwater cutter to produce biodegradable polyester resin pellets.

[0205] (Comparative Examples 1 - 3) (1) Step of manufacturing a slurry 100 mol% of 1,4 - butanediol (1,4 - BDO) as the diol component and 100 mol% of succinic acid (SA) as the aliphatic 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 1.2 of the diol with respect to the dicarboxylic acid. After that, the mixture was stirred at 40°C and 150 rpm for 30 minutes to produce a slurry without phase separation. The average particle size (D50) of the succinic acid (SA) was 200 μm, and the standard deviation with respect to the average particle size (D50) was 30.

[0206] (2) Step of manufacturing a prepolymer The slurry produced in the above step (1) was charged into a reactor through a supply line, and while charging 1500 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium - based catalyst, the temperature was raised to 245°C, and an esterification reaction was carried out for 4 hours until 95% of the by - product water was discharged to produce a prepolymer having a number - average molecular weight of 700 g / mol.

[0207] (3) Step of manufacturing a polymer To the prepolymer produced in the above step (2), 500 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium - based catalyst, and 50 ppm of triethyl phosphate, a heat stabilizer, were charged, and after stabilizing for 10 minutes, a primary polycondensation reaction was carried out at 265°C and 400 torr for 0.5 hour.

[0208] Thereafter, the primary polycondensation reaction product was charged into a disk - ring type reactor, and a secondary polycondensation reaction was carried out while rotating at 265°C and 1.0 torr for 4.5 hours to produce a polymer having a number - average molecular weight of 40000 g / mol. At this time, the secondary polycondensation reaction was carried out while removing the vapor of 1,4 - butanediol and by - products.

[0209] Thereafter, the polymer was immersed in water and cut by a cutter in water to produce biodegradable polyester resin pellets.

[0210] (Comparative Examples 1-4) (1) Step of producing a slurry The first slurry and the second slurry were produced in the same manner as in Examples 1-4.

[0211] (2) Step of producing a prepolymer The first and second slurries produced in the step (1) were charged into a reactor through a supply line, and while charging 1000 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium-based catalyst, the temperature was raised to 240°C, and an esterification reaction was carried out for 2 hours until 95% of the by-product water was discharged to produce a prepolymer having a number average molecular weight of 600 g / mol.

[0212] (3) Step of producing a polymer To the prepolymer produced in the step (2), 500 ppm of tetrabutyl titanate (Tyzor, manufactured by Dupont), a titanium-based catalyst, and 50 ppm of triethyl phosphate, a heat stabilizer, were added, and after stabilizing for 10 minutes, a first-stage polycondensation reaction was carried out at 265°C and 0.3 torr for 0.5 hour.

[0213] Thereafter, the first-stage polycondensation reaction product was charged into a disk-ring type reactor, and a second-stage polycondensation reaction was carried out while rotating at 265°C and 1.0 torr for 4.5 hours to produce a polymer having a number average molecular weight of 28000 g / mol. At this time, the second-stage polycondensation reaction was carried out while removing the vapor of 1,4-butanediol and by-products.

[0214] Thereafter, the polymer was immersed in water and cut by a cutter in water to produce biodegradable polyester resin pellets.

[0215] (Experimental Example) (Experimental Example 1-1: Polydispersity Index (PDI)) For the resin pellets produced in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4, the polydispersity index (PDI) of the resin was calculated according to the following formula A. [Formula A] JPEG2025518776000005.jpg1972In the above formula A, Mw is the weight average molecular weight (g / mol) of the resin, Mn is the number average molecular weight (g / mol) of the resin.

[0216] (Experimental Example 1-2: Number of carboxyl group end groups) The resin pellets produced in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4 were each dissolved in benzyl alcohol and dispersed in chloroform, and then phenol red, an indicator, was added. Then, using N / 10-sodium hydroxide-benzyl alcohol (sodium hydroxide benzyl alcohol primary standard solution), the carboxyl groups (-COOH) of the resin were changed to -COONa. At this time, the number of carboxyl group end groups (eq / ton) of the resin was measured by the amount of N / 10-sodium hydroxide-benzyl alcohol used.

[0217] (Experimental Example 1-3: Weight loss rate) For the resin pellets produced in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4, using a thermogravimetric analyzer (TGA550, TA Instruments), the weight loss rate (ΔW 220 , ΔW 240 and ΔW 180 ) of the resin was calculated according to the following formula 1. Note that ΔW T means the weight loss rate (%) under specific temperature (T °C) conditions.

[0218] [Formula 1] JPEG2025518776000006.jpg1284In the above formula 1, W is the weight (mg) of the biodegradable polyester resin whose moisture content has been adjusted to 100 ppm, W Tis the weight (mg) measured by a thermogravimetric analyzer after retaining the biodegradable polyester resin with the adjusted water content at T °C for 60 minutes.

[0219] (Experimental Example 1-4: Intrinsic Viscosity (IV1)) After completely dissolving 2 g of each of the resin pellets produced in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4 in 25 ml of 2-chloroform, the dropping time of the sample was measured using a BS type NO2 Ostwald viscometer, and the relative viscosity of the sample was calculated according to the following formula B. The relative viscosity value obtained by the following formula B was converted to an intrinsic viscosity (IV1, dl / g) using an automatic viscometer (SS-600-L2, manufactured by WITHLAB). [Formula B] JPEG2025518776000007.jpg2983In the above formula B, B is the correction coefficient of the viscosity tube, t0 is the dropping time (sec) measured using only 25 ml of 2-chloroform, t1 is the dropping time (sec) measured using the solution obtained by dissolving 2 g of the resin pellets in 25 ml of 2-chloroform.

[0220] [Table 1]

[0221] [Table 2]

[0222] As shown in Table 1 and Table 2 above, the biodegradable polyester resins of Examples 1-1 to 1-5 showed excellent results in terms of polydispersity index, number of carboxyl terminal groups, weight loss rate, and intrinsic viscosity compared to the resins of Comparative Examples 1-1 to 1-4.

[0223] Specifically, the biodegradable polyester resins of Examples 1-1 to 1-5 are produced by a pretreatment step and primary and secondary polycondensation reactions under specific conditions, so that the polydispersity index and the number of carboxyl end groups are appropriately adjusted, and they have an improved weight loss rate and intrinsic viscosity characteristics, and thus have excellent mechanical properties.

[0224] On the other hand, the resins of Comparative Examples 1-1 to 1-4 deviated from the appropriate numerical ranges of the polydispersity index and the number of carboxyl end groups. In particular, since the weight loss rate was very high, the mechanical properties were very low.

[0225] [Manufacture of Biodegradable Polyester Film] (Example 2-1) 10 ppm of calcium acetate, which is an electrostatic additive, was added to the resin pellets produced in Example 1-1, compounded at 180 °C, and then melt-extruded and electrostatically applied at 240 °C using a T-die to produce a biodegradable polyester film with a thickness of 400 μm.

[0226] (Example 2-2) 50 ppm of spherical silica was added to the resin pellets produced in Example 1-2, compounded at 180 °C, and then bubble-molded at 240 °C using blowing equipment (YJF-Ψ50-800L, Yuzin Engineering Co., Ltd.) to produce a biodegradable polyester film with a thickness of 100 μm.

[0227] (Example 2-3) A biodegradable polyester film with a thickness of 100 μm was produced in the same manner as in Example 2-2, except that the resin pellets produced in Example 1-3 were used instead of the resin pellets produced in Example 1-2, and 200 ppm of spherical silica was added.

[0228] (Example 2-4) 200 ppm of calcium carbonate was added to the resin pellets produced in Examples 1-4, and after compounding at 180 °C, it was molded at 240 °C using an injection molding machine (EDIS 250, Hyundai Plastic Co., Ltd.) to produce a biodegradable polyester film with a thickness of 400 μm.

[0229] (Example 2-5) 10 ppm of calcium acetate, which is an electrostatic additive, was added to the resin pellets produced in Examples 1-5, and after compounding at 180 °C, it was melt-extruded and electrostatically applied at 240 °C using a T-die to produce a biodegradable polyester film with a thickness of 400 μm.

[0230] (Comparative Example 2-1) 10 ppm of magnesium acetate, which is an electrostatic additive, was added to the resin pellets produced in Comparative Example 1-1, and after compounding at 200 °C, it was melt-extruded and electrostatically applied at 240 °C using a T-die to produce a biodegradable polyester film with a thickness of 400 μm.

[0231] (Comparative Example 2-2) A biodegradable polyester film with a thickness of 100 μm was produced in the same manner as in Example 2-2, except that the resin pellets produced in Comparative Example 1-2 were used instead of the resin pellets produced in Example 1-2, and 200 ppm of spherical silica was added.

[0232] (Comparative Example 2-3) 200 ppm of calcium carbonate was added to the resin pellets produced in Comparative Example 1-3, and after compounding at 220 °C, it was molded at 240 °C using an injection molding machine (EDIS 250, Hyundai Plastic Co., Ltd.) to produce a biodegradable polyester film with a thickness of 400 μm.

[0233] (Comparative Example 2-4) To the resin pellets produced in Comparative Examples 1-4, 10 ppm of calcium acetate, which is an electrostatic additive, was added, and after compounding at 200 °C, melt extrusion and electrostatic application were carried out at 240 °C using a T-die to produce a biodegradable polyester film with a thickness of 400 μm.

[0234] (Experimental Example) (Experimental Example 2-1: Tensile Strength) For the films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4, test pieces were produced based on the ASTM D638 Type V standard, and then experiments were carried out at a tensile speed of 100 mm / min using a universal testing machine (UTM4206-001) from INSTRON. After that, the tensile strength (MPa) was measured by a program built into the equipment.

[0235] (Experimental Example 2-2: Impact Absorption Energy) For the films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4, the impact absorption energy was measured using a Film Impact Test from Toyo Seiki Seisaku-sho, Ltd.

[0236] Specifically, the film was cut into 10 cm in length and 10 cm in width, and the amount of impact absorption energy (KJ) when the film was struck with the head of a triangular pyramid with a diameter of 16 mm and a height of 14 mm was measured. The value obtained by dividing this by the thickness (m) of the film was calculated as the impact absorption energy (KJ / m). At this time, the thickness (μm) of the film was converted to m, and it was calculated as the average value of the amount of impact absorption energy obtained by performing the measurement 10 times for each film.

[0237] (Experimental Example 2-3: Processability) For the films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4, the processability was evaluated as follows based on the presence or absence of defects such as fumes, bubbles, and fish eyes in the manufacturing process. At this time, for bubbles, air was blown in from below during the manufacturing process to observe the formation of bubbles.

[0238] 〇: No fumes, bubbles, or fish eyes are generated, the shape of the bubbles is good without being biased to one side or bursting, and the resin does not adhere to rolls or the like. Δ: Some fumes, bubbles, or fish eyes are generated, or the bubbles slightly extend and are biased to one side, but the bubbles do not burst, and the resin partially adheres to rolls or the like. ×: A large number of fumes, bubbles, or fish eyes are generated, the bubbles are biased to one side and do not form a complete shape, or the bubbles burst, and a large amount of resin adheres to the roll.

[0239] (Experimental Example 2-4: Intrinsic Viscosity (IV2)) Except for using the films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4, experiments were conducted in the same manner as in Experimental Example 1-4, and the intrinsic viscosity (IV2) of the film was calculated.

[0240] Also, the absolute value of the difference between the intrinsic viscosity (IV1) of the biodegradable polyester resin in Experimental Example 1-4 and the intrinsic viscosity (IV2) of the film was calculated.

[0241] (Experimental Example 2-5: Degree of Biodegradation) Regarding the films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4, the amount of carbon dioxide generated was measured based on KS M3100-1 to measure the degree of biodegradation. 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.

[0242] Thereafter, 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 biodegradation was calculated according to the following formula C using the measured amount of carbon dioxide generated.

[0243] [Formula C] JPEG2025518776000010.jpg13142

[0244]

Table 3

[0245]

Table 4

[0246] 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 tensile strength, impact absorption energy, processability, intrinsic viscosity, and biodegradability characteristics compared to the films of Comparative Examples 2-1 to 2-4.

[0247] Specifically, the biodegradable polyester films of Examples 2-1 to 2-5, by containing the biodegradable polyester resins of Examples 1-1 to 1-5, not only had excellent mechanical properties such as tensile strength and impact absorption energy and biodegradability, but also had excellent heat resistance, a small change value (IV drop) of the intrinsic viscosity, and a small amount of oligomer generation, so that defects such as fumes, bubbles, and fish eyes hardly occurred. In particular, the biodegradable polyester films of Examples 2-1 to 2-5 had high injection moldability and bubble stability and low pinning property in the manufacturing process, so they were excellent in productivity.

[0248] On the other hand, the films of Comparative Examples 2-1 to 2-4, by containing the resins of Comparative Examples 1-1 to 1-4, had low mechanical properties such as tensile strength and impact absorption energy, and defects such as fumes, bubbles, and fish eyes occurred in the manufacturing process. The substance containing the resin adhered to rolls and the like, resulting in very high pinning property and low bubble stability such as bubble rupture.

Claims

1. 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, having a polydispersity index (PDI) of less than 2.0, and when the weight loss rate (%) under specific temperature (T °C) conditions according to the following formula 1 is ΔW Ｔ then ΔW ２２０ is 1.3% or less, a biodegradable polyester resin: [Formula 1] In the above formula 1, W is the weight (mg) of the biodegradable polyester resin whose water content is adjusted to 100 ppm, W Ｔ is the weight (mg) measured by a thermogravimetric analyzer by retaining the biodegradable polyester resin with the water content adjusted to 100 ppm at T °C for 60 minutes.

2. The biodegradable polyester resin according to claim 1, satisfying the following formula 2: [Formula 2] |ΔW ２４０ - ΔW １８０ |≤ 1.5%.

3. The ΔW ２４０ is 0.1% to 2.0%, and the ΔW １８０ is 0.05% to 0.3%, the biodegradable polyester resin according to claim 2.

4. The first diol residue and the second diol residue each contain a residue of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof, the residue of the aromatic dicarboxylic acid contains a residue of terephthalic acid, dimethyl terephthalate, or a derivative thereof, and the residue of the aliphatic dicarboxylic acid contains a residue of adipic acid, succinic acid, sebacic acid, or a derivative thereof, the biodegradable polyester resin according to claim 1.

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

6. The aliphatic dicarboxylic acid includes adipic acid, The adipic acid has a number-based average particle size (D50) measured by a particle size analyzer Microtrac S3500 in the particle size distribution (PSD) of 50 μm to 500 μm, and a standard deviation with respect to the average particle size (D50) of 100 or less. The biodegradable polyester resin according to claim 4.

7. The ratio (X / Y) of the number (X) of the first repeating units and the number (Y) of the second repeating units is 0.8 to 3.0, The number of carboxyl terminal groups of the biodegradable polyester resin is 50 eq / ton or less. The biodegradable polyester resin according to claim 1.

8. 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. The biodegradable polyester resin includes one or more types of nanocellulose selected from the group consisting of cellulose nanocrystals, cellulose nanofibers, and microfibrillated cellulose, The average particle size of the nanocellulose is 100 nm or more, and the particle size deviation is 32% or less. The biodegradable polyester resin according to claim 1.

10. A step of pretreating a mixture of diol and dicarboxylic acid to produce a slurry, A step of subjecting the slurry to an esterification reaction to produce a prepolymer, A method for producing a biodegradable polyester resin, comprising: a step of subjecting the prepolymer to a polycondensation reaction to produce a polymer. The biodegradable polyester resin includes a first repeating unit containing a first diol residue and an aromatic dicarboxylic acid residue, and a second repeating unit containing a second diol residue and an aliphatic dicarboxylic acid residue. The polydispersity index (PDI) of the biodegradable polyester resin is less than 2.0, and the weight loss rate (%) under the specific temperature (T °C) condition according to the following formula 1 is ΔW. Ｔ When it is set as ΔW ２２０ A method for producing a biodegradable polyester resin, wherein ΔW is 1.3% or less. [Formula 1] In the above formula 1, W is the weight (mg) of the biodegradable polyester resin whose moisture content is adjusted to 100 ppm. W Ｔ is the weight (mg) measured by a thermogravimetric analyzer after retaining the biodegradable polyester resin with the adjusted moisture content at T °C for 60 minutes.

11. The method for producing a biodegradable polyester resin according to claim 10, wherein the step of producing the slurry is performed by stirring a mixture of the diol and the dicarboxylic acid at 25 °C to 85 °C at 50 rpm to 200 rpm for 10 minutes or more.

12. The step of producing the slurry is a step of pretreating a mixture of the first diol and the aromatic dicarboxylic acid to produce a first slurry, and a step of pretreating a mixture of the second diol and the aliphatic dicarboxylic acid to produce a second slurry. The method for producing a biodegradable polyester resin according to claim 10.

13. The step of producing the prepolymer is a step of subjecting the first slurry to a primary esterification reaction at 190 °C to 260 °C, and A method for producing a biodegradable polyester resin according to claim 12, comprising the step of adding the secondary slurry to the primary esterification reaction product and performing a secondary esterification reaction at 160°C to 240°C.

14. The step of producing the polymer comprises subjecting the prepolymer to a first polycondensation reaction at a temperature of 255°C or lower and a pressure of 1 torr to 100 torr for 0.5 hour to 3 hours, and subjecting the first polycondensation reaction product to a second polycondensation reaction at a temperature of 210°C to 250°C while reducing the pressure to 1 torr for 0.5 hour or more. A method for producing a biodegradable polyester resin according to claim 10.

15. A biodegradable polyester film containing a biodegradable polyester resin, wherein the biodegradable polyester resin contains 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, the polydispersity index (PDI) of the biodegradable polyester resin is less than 2.0, and when the weight loss rate (%) under specific temperature (T°C) conditions according to the following formula 1 is ΔW Ｔ then ΔW ２２０ of the biodegradable polyester resin is 1.3% or less. A biodegradable polyester film: [Formula 1] In the above formula 1, W is the weight (mg) of the biodegradable polyester resin whose moisture content has been adjusted to 100 ppm, W Ｔ is the weight (mg) measured by a thermogravimetric analyzer by retaining the biodegradable polyester resin with the adjusted moisture content at T°C for 60 minutes.

16. The biodegradable polyester film according to claim 15, wherein the tensile strength of the biodegradable polyester film is 30 MPa or more and the impact absorption energy is 5.0 KJ / m or more.

17. The biodegradable polyester film according to claim 15, which satisfies the following formula 3: [Formula 3] |IV １ -IV ２ |≤0.2 In the above formula 3, IV １ is the intrinsic viscosity (dl / g) of the biodegradable polyester resin, IV ２ is the intrinsic viscosity (dl / g) of the biodegradable polyester film.

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