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] Examples of implementations relate to biodegradable polyester resin, a method for producing the same, and a biodegradable polyester film containing the same. [Background technology]

[0002] In recent years, as concerns about environmental issues have grown, solutions to the disposal problems of various everyday products, especially disposable products, are needed. Specifically, polymer materials are inexpensive and have excellent properties such as processability, and are widely used to manufacture various products such as films, fibers, packaging materials, bottles, and containers. However, when these products reach the end of their lifespan, they release harmful substances when incinerated, and some types take hundreds of years to decompose completely in nature.

[0003] To overcome the limitations of such polymers, research on biodegradable polymers that decompose more quickly is being actively conducted. Examples of biodegradable polymers used include polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxy alkanoate (PHA), and polycaprolactone (PCL). However, compared to non-degradable resins such as polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP), these polymers have lower mechanical properties such as tensile strength and impact strength, lower melting points, and poor heat resistance, making processing difficult and resulting in low productivity. Therefore, there is a need for research into biodegradable polymer resins that maintain biodegradability and mechanical properties while also possessing excellent heat resistance, improving processability, and increasing productivity.

[0004] For 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 blending methods have limitations in improving durability, heat resistance, etc. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Korean Published Patent Publication No. 2012-0103158 [Overview of the project] [Problems that the invention aims to solve]

[0006] Therefore, the practical application aims to provide a biodegradable polyester resin that is excellent in all aspects, including biodegradability, mechanical properties such as tensile strength and impact strength, and heat resistance, as well as processability and productivity, a method for producing the same, and a biodegradable polyester film containing the same. [Means for solving the problem]

[0007] One example of a biodegradable polyester resin comprises 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 is given by ΔW according to Formula 1 below. T When this is the case, ΔW 220 The percentage is 1.3% or less.

[0008] [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. WT This is the weight (mg) of the biodegradable polyester resin with adjusted moisture content, measured by a thermogravimetric analyzer after being left at T°C for 60 minutes.

[0009] Another example of a method for producing a biodegradable polyester resin includes the steps of: pre-treating a mixture of a diol and a dicarboxylic acid to produce a slurry; esterifying the slurry to produce a prepolymer; and condensing the prepolymer to produce a polymer, wherein the biodegradable polyester resin comprises 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 specific temperature (T°C) conditions according to formula 1 is ΔW T In this case, the ΔW of the biodegradable polyester resin 220 The percentage is 1.3% or less.

[0010] Another example of a biodegradable polyester film includes a biodegradable polyester resin, wherein the biodegradable polyester resin includes a first repeating unit comprising a first diol residue and an aromatic dicarboxylic acid residue, and a second repeating unit comprising 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 specific temperature (T°C) conditions according to formula 1 is ΔW T In this case, the ΔW of the biodegradable polyester resin 220 The percentage is 1.3% or less. [Effects of the Invention]

[0011] The biodegradable polyester resins in the real-world examples have a polydispersity index (PDI) of less than 2.0, and a weight loss rate (ΔW) calculated using Equation 1. 220 By satisfying a requirement of 1.3% or less, it is possible to improve biodegradability, mechanical properties such as tensile strength and impact strength, and heat resistance.

[0012] In addition, when a film is produced using the biodegradable polyester resin, defects such as fume, bubbles, and fisheye do not occur, so that the processing suitability 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.

Embodiments 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 deformed 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", unless there is a contrary description, it does not exclude other components, but means that it may further include other components.

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

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

[0018] Polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), and polycaprolactone (PCL), which are widely used as biodegradable polymers, have lower mechanical properties such as tensile strength and impact strength compared to non-biodegradable resins such as polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP). They also have lower melting points and poor heat resistance, making their processing difficult and resulting in poor productivity.

[0019] Specifically, the manufacturing of molded products such as films using resin involves processes such as compounding, extrusion and stretching, extrusion and blow molding, and injection molding. However, in the case of biodegradable resins, if heat above 180°C is applied during these manufacturing processes, degradation of the polymer can easily occur. This can lead to a decrease in quality, such as the vaporization of oligomers and the generation of fumes, or the deposition of oligomers as a white substance, potentially reducing mechanical properties such as tensile strength and impact strength.

[0020] In particular, in the compounding process, twin screws are commonly used to enhance mixing properties. However, the shear stress between the screw element and the biodegradable resin can accelerate the thermal decomposition of the resin. Consequently, the intrinsic viscosity drop (IV drop), which is the absolute difference between the intrinsic viscosity of the resin and the intrinsic viscosity of the film produced therefrom, can become large, maximizing fume generation and potentially causing yellowing or browning.

[0021] In addition, in the extrusion and stretching processes, oligomers may accumulate on a casting drum and scatter, causing wire breakage by an electrostatic application method and halting production. Deteriorated polymers may generate as bubbles or voids, which can lead to a decline in quality and productivity. In the extrusion and blow processes, oligomers may act as a defect in bubble formation, reducing the stability of the bubbles, such as causing the bubbles to burst. Also, 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 processing suitability and productivity, and providing 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. Therefore, even when enhanced 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 manufactured therefrom, is low, with little fume generation, and little yellowing or browning. Also, even when an electrostatic additive is added in extremely small amounts in the extrusion and stretching processes, wire breakage does not occur, bubbles are well formed in the blow process with high bubble stability, and little fish eye or fusion between film surfaces occurs in the injection process.

[0024] [Biodegradable Polyester Resin] One example of a biodegradable polyester resin comprises 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 is given by ΔW according to Formula 1 below. T When this is the case, ΔW 220 The percentage 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 has been adjusted to 100 ppm. W T This is the weight (mg) of the biodegradable polyester resin with adjusted moisture content, measured by a thermogravimetric analyzer after being left at T°C for 60 minutes.

[0026] According to one example, the biodegradable polyester resin contains 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. Furthermore, the biodegradable polyester resin may contain 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. By including the first and second repeating units, the biodegradable polyester resin can improve its biodegradability and mechanical properties.

[0028] The diol residue may include, as the first and second diol residues, residues of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or derivatives thereof. The first and second diol residues may be identical 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, residues of 1,4-butanediol or derivatives thereof. The inclusion of a 1,4-butanediol residue in the diol residue may be even more advantageous in that it may improve biodegradability, mechanical properties such as tensile strength, and heat resistance.

[0029] Furthermore, the aromatic dicarboxylic acid residue may include terephthalic acid, dimethyl terephthalate, or a derivative thereof, and the aliphatic dicarboxylic acid residue may include adipic acid, succinic acid, sebacic acid, or a derivative thereof.

[0030] According to one example, the aromatic dicarboxylic acid may include terephthalic acid. Specifically, the terephthalic acid may have a particle size distribution (PSD) of 10 μm to 400 μm, measured by a Microtrac S3500 particle size analyzer, with a standard deviation of 100 or less from the average particle size (D50).

[0031] Specifically, when the aromatic dicarboxylic acid contains terephthalic acid, the terephthalic acid is perfectly crystalline, has no melting point, and is a white crystal that sublimes at approximately 300°C. Because its solubility in the diol is very low, the uniformity of the reaction may be low. The aromatic dicarboxylic acid in the realization example can further improve crystallinity and thermal stability by containing terephthalic acid whose average particle size and standard deviation satisfy the aforementioned range.

[0032] For example, the average particle size (D50) of the terephthalic acid may 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] Furthermore, the standard deviation of the average particle size (D50) of terephthalic acid is 90 or less, 80 or less, 65 or less, 50 or less, or 30 or less, and can be 5-90, 5-70, 10-60, 12-45, 15-40, or 15-30.

[0034] By satisfying the aforementioned ranges for the average particle size and standard deviation of terephthalic acid, the solubility in diols can be improved, which may be advantageous in terms of the esterification reaction rate in subsequent steps. Specifically, by satisfying the aforementioned ranges for the average particle size and standard deviation of terephthalic acid, the physical properties can be maintained, and the esterification reaction time can be shortened by 1.5 times or more, which may be more preferable in terms of reaction efficiency.

[0035] Furthermore, if the average particle size (D50) of terephthalic acid is less than 10 μm, it is undesirable because the average particle size (D50) is too small and can be converted from single primary particles to aggregated secondary particles. If the average particle size (D50) of terephthalic acid exceeds 400 μm, the average particle size (D50) is too large, which can reduce the solubility in the diol, slow down the esterification reaction rate, and also reduce the uniformity of the reaction.

[0036] Furthermore, according to other realizations, the aromatic dicarboxylic acid may include dimethyl terephthalate. Specifically, the dimethyl terephthalate, when measured in a molten or particulate state, may be within a range similar to the average particle size (D50) and its standard deviation of the terephthalic acid.

[0037] Furthermore, according to other realization examples, the aliphatic dicarboxylic acid may include adipic acid. Specifically, the adipic acid may have a particle size distribution (PSD) of 50 μm to 500 μm, measured by a Microtrac S3500 particle size analyzer, with a standard deviation of 100 or less from the average particle size (D50).

[0038] For example, the average particle size (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] Furthermore, the standard deviation of the average particle size (D50) of the adipic acid is 90 or less, 70 or less, 55 or less, 40 or less, or 30 or less, and can be 5-90, 5-65, 10-60, 12-45, 15-40, or 16-30.

[0040] By satisfying the aforementioned ranges for the average particle size of adipic acid and its standard deviation, dispersibility can be further improved, which may be even more advantageous in terms of the esterification reaction rate in subsequent steps. Specifically, by satisfying the aforementioned ranges for the average particle size of adipic acid and its standard deviation, the physical properties can be maintained, and the esterification reaction time can be shortened by 1.5 times or more, which may be more preferable in terms of reaction efficiency.

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

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

[0043] By satisfying the above configuration, the first repeating unit and the second repeating unit can further improve mechanical properties such as biodegradability and tensile strength, as well as heat resistance.

[0044] Specifically, in order for the biodegradable polyester resin used in the implementation example to exhibit excellent biodegradability and improve mechanical properties, dimensional stability, moldability, and productivity, it is extremely important to adjust the number of the first repeating units and the second repeating units that constitute the biodegradable polyester resin.

[0045] Generally, polyester resins, such as polybutylene adipate terephthalate (PBAT) resins, have excellent flexibility but poor impact resistance, making them prone to tearing and bursting, and their low stiffness has limited their applications. However, the biodegradable polyester resins demonstrated in this example can be improved in terms of biodegradability, mechanical properties, dimensional stability, moldability, and productivity by adjusting the number of the first and second repeating units.

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

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

[0048] By satisfying the aforementioned ranges for both the number of first repeating units and the number of second repeating units, biodegradability, mechanical properties, heat resistance, dimensional stability, moldability, and productivity can all be improved.

[0049] In particular, the second repeating unit, which includes the second diol residue and the aliphatic dicarboxylic acid residue, consists of a linear chain and contains aliphatic dicarboxylic acid residues that can affect the adhesive properties. Therefore, the crystallinity can be controlled according to the content of these residues, and by satisfying the aforementioned range, improvements in mechanical properties such as tensile strength and heat resistance can be maximized.

[0050] Furthermore, the ratio (X / Y) of the number of first repeating units (X) to the number of second repeating units (Y) can be between 0.8 and 3.0. For example, the ratio (X / Y) of the number of first repeating units (X) to the number of second repeating units (Y) can be between 0.8 and 2.9, 0.8 and 2.55, 0.83 and 2.15, 0.83 and 1.85, 0.85 and 1.6, 0.85 and 1.3, or 0.85 and 1.1.

[0051] By satisfying the aforementioned range, the ratio (X / Y) of the number of first repeating units (X) to the number of second repeating units (Y) can improve mechanical properties such as tensile strength. In particular, when the blow molding process is performed using the biodegradable polyester resin, bubble stability can be improved, such as when bubbles maintain a uniform shape without bursting. Furthermore, when the injection molding process is performed using the biodegradable polyester resin, the occurrence of fisheyes and fusion between film surfaces can be effectively prevented, thereby improving quality and processability.

[0052] According to one 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, the inclusion of the first and second repeating units in the form of block copolymers is advantageous for generating microcrystals when oriented crystals are formed during the stretching process using the biodegradable polyester resin, as steric hindrance does not occur, allowing for sufficiently effective crystallization. Therefore, a biodegradable polyester resin containing the first and second repeating units in the form of block copolymers allows for successful induction of oriented crystals during stretching, forming a dense crystalline structure, thereby maximizing the mechanical properties, such as the tensile strength, and dimensional stability of molded articles, particularly films, produced using this resin.

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

[0055] Specifically, the nanocellulose may be one or more selected from the group consisting of cellulose nanocrystals, cellulose nanofibers, microfibrillated cellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, cellulose acetate, methylcellulose, ethylcellulose, propylcellulose, butylcellulose, pentylcellulose, hexylcellulose, and cyclohexylcellulose. 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 larger, and the particle size deviation may be 32% or less. For example, the average particle size of the nanocellulose is 100 nm or larger, 120 nm or larger, or 140 nm or larger, and ranges from 100 nm to 1500 nm, 115 nm to 1200 nm, 120 nm to 950 nm, 135 nm to 700 nm, or 140 nm to 550 nm, and the particle size deviation of the nanocellulose may 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 using a nanoparticle size analyzer (e.g., Zetasizer Nano ZS). Specifically, for the nanocellulose, the average particle size and particle size deviation can be calculated using Zetasizer software with Zetasizer Nano ZS (Malvern). More specifically, the average particle size and particle size deviation were measured based on the principle of dynamic light scattering (DLS) at a temperature of 25°C and a measurement angle of 175°. In this case, the peak value derived from the polydispersity index (PDI) with a confidence interval of 0.5 was measured as the particle size.

[0058] Furthermore, the biodegradable polyester resin may contain nanocellulose in an amount of 3000 ppm or less. For example, the nanocellulose content may be 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 may range from 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] Furthermore, the nanocellulose may be pre-treated by bead milling, ultrasonication, stirring, or hydrophobication. Specifically, the nanocellulose may be water-dispersed nanocellulose that has been pre-treated by bead milling, ultrasonication, stirring, or hydrophobication.

[0060] First, the bead mill pretreatment can be carried out by a wet milling device such as a vertical mill or a horizontal mill. A horizontal mill may be preferred, but is not limited to it, because it can hold a larger quantity of beads in the chamber, reduces uneven wear on the machine, reduces bead wear, and is easier to maintain.

[0061] The bead mill pretreatment may be carried out using one or more beads selected from the group consisting of zirconium, zircon, zirconia, quartz, and aluminum oxide.

[0062] Specifically, the bead mill pretreatment may be performed using beads having a diameter of 0.3 mm to 1 mm. For example, the diameter of the beads may 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 for 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 may increase, which may reduce dispersibility.

[0063] Furthermore, the bead mill pretreatment may be preferable if beads with a specific gravity higher than that of nanocellulose are used, as this allows for sufficient energy transfer. For example, the beads are one or more selected from the group consisting of zirconium, zircon, zirconia, quartz, and aluminum oxide, which have a specific gravity higher than that of water-dispersed nanocellulose. Zirconium beads with a specific gravity four times or more higher than that of water-dispersed nanocellulose may be preferred, but are not limited to this.

[0064] The bead mill pretreatment may be performed by filling the chamber with 80% or more beads and at a linear velocity of 20 m / sec or less. For example, the bead mill pretreatment may be performed with a chamber bead filling rate 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 above ranges for filling rate and linear velocity, the effect of the bead mill pretreatment, i.e., improvement of dispersibility, can be maximized.

[0065] Furthermore, the ultrasonic pretreatment is a method of physically crushing or pulverizing nanoparticles by generating waves from 20 kHz ultrasonic waves (ultrasound) released into a solution.

[0066] Specifically, the ultrasonic pretreatment may be performed with an energy level of 30,000 J or less for a period of less than 30 minutes. For example, the ultrasonic pretreatment may be performed with an energy level of 30,000 J or less, 26,000 J or less, 24,500 J or less, 22,000 J or less, 19,500 J or less, 16,500 J or less, or 16,000 J or less for a period 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 above ranges for the energy level and duration of the ultrasonic pretreatment, the effect of the ultrasonic pretreatment, i.e., the improvement in dispersibility, can be maximized.

[0067] According to one example, the nanocellulose may be pre-treated with a bead mill or ultrasonically. Alternatively, the nanocellulose may be pre-treated with both a bead mill and ultrasonically. In this case, it may be preferable to perform ultrasonic pre-treatment after bead mill pre-treatment in order to prevent re-aggregation and improve dispersibility.

[0068] If the nanocellulose, specifically the water-dispersed nanocellulose, is pre-treated with a bead mill or ultrasonic pre-treatment, its dispersibility can be maximized, potentially resulting in a higher number of cellulose particles. Specifically, water-dispersed nanocellulose that has been additionally pre-treated with a bead mill or ultrasonic pre-treatment may have a higher number of cellulose particles at the same content compared to water-dispersed nanocellulose that has not been pre-treated with a bead mill or ultrasonic pre-treatment. Therefore, additional pre-treatment with a bead mill or ultrasonic pre-treatment of the nanocellulose can further improve its dispersion stability.

[0069] Furthermore, the aforementioned pre-mixing treatment may be performed at a speed of 10,000 rpm or less for 1 to 90 minutes. For example, the pre-mixing treatment may be performed using a stirrer or homogenizer at a speed of 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] Furthermore, the hydrophobic pretreatment can be carried out by one or more methods selected from the group consisting of acetylation, silanation, crosslinking, fluorination, AKD (Alkyl Ketene Dimer) addition, and ASA (alkyl succinic anhydride) addition.

[0071] Specifically, the dimensional stability can be further improved by replacing some of the hydroxyl groups of the nanocellulose with hydrophobic groups that have a lower affinity for water using the hydrophobic treatment method described above. For example, the silanization can be carried out using MTMS (methyltrimethoxysilane), TMOS (tetramethoxysilane), DMDMS (dimethoxydimethylsilane), MAPTMS (3-methyl-acryl-oxypropyl trimethoxysilane), TBOT (titanium butoxide), or TMPS (trimethoxyphenyl-silane), but is not limited to these.

[0072] The polydispersity index (PDI) of the biodegradable polyester resin in the implemented examples is less than 2.0. For example, the polydispersity index of the biodegradable polyester resin may be less than 2.0, 1.95 or less, or 1.9 or less.

[0073] By adjusting the polydispersity index to the aforementioned range, heat resistance can be further improved. Specifically, if the polydispersity index exceeds the aforementioned range, the heat resistance of the biodegradable polyester resin decreases, making it more susceptible to polymer degradation. Therefore, when molded products such as films are manufactured using the biodegradable polyester resin, the incidence of polymer degradation in the process is low, thus improving processability and productivity.

[0074] The aforementioned multivariance index can be calculated using the following formula A. [Formula A] JPEG0007909627000003.jpg1152 In 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.

[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, the weight loss rate (%) under specific temperature (T°C) conditions is given by the following formula 1: ΔW T In this case, the ΔW of the biodegradable polyester resin 220 It may be 1.3% or less. Note that ΔW T This refers to the percentage of weight loss under specific temperature (T°C) conditions.

[0077] [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 TThis is the weight (mg) of the biodegradable polyester resin with adjusted moisture content, measured by a thermogravimetric analyzer after being left at T°C for 60 minutes.

[0078] Specifically, the ΔW of the biodegradable polyester resin 220 This can be 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 is the weight loss rate at 220°C, a typical process temperature for manufacturing molded products such as films using resin. 220 By satisfying the above range, the biodegradable polyester resin can have excellent heat resistance.

[0079] Furthermore, the biodegradable polyester resin may satisfy the following formula 2. [Formula 2] |ΔW 240 -ΔW 180 |≦1.5% Specifically, the ΔW 240 and ΔW 180 These can each be calculated according to Equation 1. For example, ΔW 240 This is the weight loss rate at 240°C, and can be 0.1%~2.0%, 0.2%~1.9%, 0.3%~1.8%, 0.45%~1.55%, 0.5%~1.4%, 0.5%~1.2%, 0.55%~1.15%, or 0.6%~1.1%. Also, ΔW 180 This 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 obtained by 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 range from 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] The biodegradable polyester resin may have excellent heat resistance if the value obtained by formula 2 satisfies the range described above. Specifically, the smaller the difference in weight loss rates over a wide temperature range of 180°C to 240°C, the better the heat resistance. This allows for flexible application of process conditions, thereby further improving processability and productivity.

[0082] Furthermore, the number of carboxyl end groups in the biodegradable polyester resin may be 50 eq / ton or less. For example, the number of carboxyl end groups in the biodegradable polyester resin may be 50 eq / ton or less, 48 ​​eq / ton or less, 45 eq / ton or less, 42 eq / ton or less, or 35 eq / ton or less. By adjusting the number of carboxyl end groups to the above range, the rate of polymer degradation can be reduced in the process of manufacturing molded products such as films using the biodegradable polyester resin, and both mechanical properties such as tensile strength and heat resistance can be improved.

[0083] Furthermore, the intrinsic viscosity (IV) of the biodegradable polyester resin may be 1.1 dl / g or higher. For example, the intrinsic viscosity (IV) of the biodegradable polyester resin may be 1.15 dl / g or higher, 1.23 dl / g or higher, 1.3 dl / g or higher, 1.4 dl / g or higher, 1.45 dl / g or higher, 1.5 dl / g or higher, 1.55 dl / g or higher, or 1.62 dl / g or higher. [Method for producing biodegradable polyester resin] Another example of a method for producing a biodegradable polyester resin is a method for producing a biodegradable polyester resin comprising the steps of: pre-treating a mixture of a diol and a dicarboxylic acid to produce a slurry; esterifying the slurry to produce a prepolymer; and condensing the prepolymer to produce a polymer, wherein the biodegradable polyester resin comprises 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 specific temperature (T°C) conditions according to formula 1 is ΔWT In this case, the ΔW of the biodegradable polyester resin 220 The percentage is 1.3% or less.

[0084] First, a slurry is prepared by pre-treating a mixture of diol and dicarboxylic acid.

[0085] The diol may include 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or derivatives thereof as its diol component. Specifically, the diol may include 1,4-butanediol, 1,2-ethanediol, or derivatives thereof, and may include 1,4-butanediol or derivatives thereof. When the diol includes 1,4-butanediol as its diol component, in particular when the diol consists solely of 1,4-butanediol, it may be more advantageous in that it can improve biodegradability, mechanical properties such as tensile strength, and heat resistance. The diol may also include a biomass-based diol component.

[0086] For example, the diol may contain a primary diol and a secondary diol as diol components, and may contain 95 mol% or more of 1,4-butanediol, 1,2-ethanediol, 1,3-propanediol, or a derivative thereof. For example, the diol may contain 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, based on the total number of moles of diol components.

[0087] Furthermore, the dicarboxylic acid may include aromatic dicarboxylic acids and aliphatic dicarboxylic acids as dicarboxylic acid components. Specifically, the aromatic dicarboxylic acid may include terephthalic acid, dimethyl terephthalate, or derivatives thereof, and the aliphatic dicarboxylic acid may include adipic acid, succinic acid, sebacic acid, or derivatives thereof.

[0088] The dicarboxylic acid may contain 30 mol% or more of aromatic dicarboxylic acid based on the total number of moles of dicarboxylic acid components. For example, the content of 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 dicarboxylic acid components, 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 aliphatic dicarboxylic acid based on the total number of moles of dicarboxylic acid components. 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 dicarboxylic acid components, 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 content of the aromatic dicarboxylic acid and aliphatic dicarboxylic acid within the aforementioned range, and in particular by controlling the content of the aliphatic dicarboxylic acid within the aforementioned 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] Furthermore, the step of producing the slurry may be carried out by stirring the 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] In another example, the step of producing the slurry may include the step of pre-treating a mixture of the first diol and the aromatic dicarboxylic acid to produce a first slurry, and the step of pre-treating a mixture of the second diol and the aliphatic dicarboxylic acid to produce a second slurry.

[0093] Specifically, by mixing and pre-treating the diol and dicarboxylic acid to form a slurry, not only can the diol and dicarboxylic acid react uniformly, but it is also effective in rapidly advancing the esterification reaction, thereby increasing the reaction efficiency.

[0094] In particular, when an aromatic dicarboxylic acid, such as terephthalic acid, has perfect crystalline properties and is in powder form, its solubility in the diol is very low, making a homogeneous reaction difficult. Therefore, the step of pre-treating and producing the slurry, especially the step of producing the first slurry, can play a very important role in increasing the reaction efficiency of the biodegradable polyester resin having excellent physical properties as demonstrated in the realization example.

[0095] Furthermore, by performing the aforementioned pretreatment to produce the first slurry, it is possible to prevent the diol from undergoing an esterification reaction with the aliphatic dicarboxylic acid beforehand, making it even easier to control the number and ratio of the first and second repeating units.

[0096] On the other hand, in the aforementioned pretreatment, the structure and physical properties of the biodegradable polyester resin can change depending on the particle size and standard deviation of the aromatic dicarboxylic acid, the particle size distribution, and the pretreatment reaction conditions, so it is very important to control these factors.

[0097] According to one example, the aromatic dicarboxylic acid may include terephthalic acid. The explanation regarding the average particle size (D50) of 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, further improving crystallinity and thermal stability.

[0099] In other realizations, the aromatic dicarboxylic acid may include dimethyl terephthalate. Unlike terephthalic acid, dimethyl terephthalate has a melting point of about 142°C, so it may be more preferable in terms of esterification reaction rate and reaction efficiency to convert it to a molten state at 170°C and then mix it with the first diol.

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

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

[0102] The aforementioned pretreatment can be carried out by introducing the diol and dicarboxylic acid into a slurry stirrer (tank). Since it is very important to control the stirring force until the mixture of the diol and dicarboxylic acid becomes a slurry, process conditions such as the number and shape of the stirring blades of the stirrer, as well as the pretreatment temperature and stirring speed, are very important.

[0103] Specifically, the slurry agitator may have an anchor-type base, more specifically, a height of 20 mm or more to the agitator, and may be equipped with two or more rotating blades. Having such a structure in the slurry agitator can further improve the efficiency of slurry formation.

[0104] For example, if the slurry stirrer is positioned such that the height to the stirrer is 20 mm or more, and the reactor and the bottom of the stirrer are almost touching, then the efficiency of slurry formation can be further improved by ensuring that the slurry is obtained without sedimentation. 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, causing phase separation.

[0105] Furthermore, the pretreatment may be carried out by stirring the mixture of the diol and the aromatic dicarboxylic acid at 50 rpm to 500 rpm for 10 minutes or more at 25°C to 100°C. For example, the pretreatment may be carried out at temperatures of 25°C to 85°C, 28°C to 60°C, 30°C to 55°C, or 26°C to 50°C, at stirring speeds 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 ensuring that the temperature, stirring speed, and time of the pretreatment step satisfy the aforementioned ranges, a homogeneous slurry without phase separation can be obtained more efficiently, which may be even more preferable in terms of esterification reaction rate and reaction efficiency.

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

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

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

[0110] For example, the first esterification reaction may be carried out at temperatures below 240°C, below 235°C, between 180°C and 250°C, between 180°C and 245°C, between 185°C and 240°C, between 190°C and 250°C, between 190°C and 245°C, between 195°C and 245°C, or between 200°C and 240°C, until 95% of the by-product water is discharged. Alternatively, the first esterification reaction may be carried out for 0.5 to 4.5 hours, 0.5 to 4 hours, 0.5 to 3.5 hours, 0.7 to 4.5 hours, 0.7 to 4 hours, 0.7 to 3.5 hours, or 1 to 3.5 hours.

[0111] In another example, the step of producing the prepolymer may include the steps of: subjecting the first slurry to a primary esterification reaction at 190°C to 260°C; and 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 may 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 to 4 hours, 1.5 to 3.5 hours, or 2 to 3 hours.

[0113] The secondary esterification reaction may 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 to 3 hours, 1 to 2.5 hours, or 1.5 to 2.2 hours.

[0114] Furthermore, according to other examples, the method for producing the biodegradable polyester resin may further include a step of adding nanocellulose. The explanation regarding nanocellulose is as described above.

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

[0116] In this case, adding the nanocellulose before the secondary esterification reaction, compared to adding it before the primary esterification reaction, can improve the bonding strength of the nanocellulose, thereby further improving its biodegradability, thermal properties, and durability.

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

[0118] The amount of nanocellulose added may be 3000 ppm or less, based on the total weight of the primary esterification product, the secondary esterification product, or the mixture of the second diol and the aliphatic dicarboxylic acid. For example, it may be added at a concentration of 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, based on the total weight of the primary esterification product, the secondary esterification product, or the mixture of the second diol and the aliphatic dicarboxylic acid, and additional nanocellulose may be added at concentrations 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.

[0119] Furthermore, the nanocellulose may be introduced at temperatures 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 is preferable that the introduction temperature of the nanocellulose falls within these ranges, as this may improve mechanical properties such as tensile strength and durability.

[0120] Furthermore, the nanocellulose can be 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 to prevent aggregation, improve strength, impact strength, and heat resistance, and maintain an appropriate process speed. If the introduction speed is below the above range, an additional process will be required, and the speed will be too slow, reducing efficiency. If the introduction speed exceeds the above range, re-aggregation may occur, potentially reducing tensile strength and heat resistance.

[0121] Furthermore, a titanium-based catalyst or a germanium-based catalyst may be added before the esterification reaction step and / or before the condensation polymerization reaction step described below.

[0122] For example, one or more catalysts selected from the group consisting of titanium isopropoxide, tetrapropyl titanate, tetrabutyl titanate, tetraisopropyl titanate, germanium oxide, germanium methoxide, germanium ethoxide, tetramethylgermanium, tetraethylgermanium, and germanium sulfide may be added before the esterification reaction step and / or before the condensation polymerization reaction step.

[0123] In this case, the amount of catalyst added may be between 100 ppm and 1000 ppm. For example, the amount of catalyst added may be between 100 ppm and 650 ppm, 120 ppm and 500 ppm, or 150 ppm and 350 ppm, based on the total weight of the diol, aromatic dicarboxylic acid, and aliphatic dicarboxylic acid. Furthermore, if the catalyst is added to both the esterification reaction and the condensation polymerization reaction, the total amount of catalyst added may be 1200 ppm or less, 950 ppm or less, or 880 ppm or less.

[0124] Furthermore, before the esterification reaction step and / or before the polymerization condensation reaction step described below, an amine-based high-temperature heat stabilizer such as tetraethylenepentaamine; one or more phosphorus-based stabilizers selected from the group consisting of phosphoric acid, phosphorous acid, polyphosphate, trimethyl phosphate, triethyl phosphate, triethyl phosphonoacetate, trimethylphosphine, and triphenylphosphine; or a branching agent such as glycerol may be added. For example, the stabilizer may be added before the secondary esterification reaction step or before the polymerization condensation reaction step described below, and the branching agent may be added before the primary esterification reaction step and / or before the secondary esterification reaction step.

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

[0126] Furthermore, before the step of carrying out the condensation polymerization reaction described below, one or more additives selected from the group consisting of silica, potassium, or magnesium, and color correctors such as cobalt acetate may be added. Specifically, after the esterification reaction is completed, the additives and / or color correctors may be added to stabilize the mixture before proceeding with the condensation polymerization reaction.

[0127] The number-average molecular weight of the aforementioned prepolymer may range from 800 g / mol to 30,000 g / mol. For example, the number-average molecular weight of the aforementioned prepolymer may range from 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 aforementioned number-average molecular weight can be measured using gel permeation chromatography (GPC). Specifically, the data obtained by gel permeation chromatography includes various parameters such as Mn, Mw, and Mp, and the molecular weight can be measured using the number-average molecular weight (Mn) as the reference.

[0129] Subsequently, the prepolymer is subjected to a condensation polymerization reaction to produce a polymer.

[0130] Specifically, the condensation polymerization reaction can be carried out in two stages. For example, after the preliminary polymer undergoes a primary condensation polymerization reaction, it can be placed in a disc ring type reactor and subjected to a secondary condensation polymerization reaction to obtain the polymer. In this case, the secondary condensation polymerization can be carried out while removing the vapor and by-products of 1,4-butanediol.

[0131] The primary condensation polymerization reaction may be carried out at a temperature of 255°C or lower, 250°C or lower, 245°C or lower, 240°C or lower, 215°C to 255°C, 225°C to 245°C, or 230°C to 242°C, and at 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 a period of 0.5 to 3 hours, 1 hour to 2.5 hours, or 1.5 to 2 hours.

[0132] Furthermore, the secondary condensation polymerization reaction may be carried out at a temperature of 210°C to 250°C, 215°C to 245°C, or 225°C to 240°C, while reducing the pressure to 1 torr or less, 0.8 torr or less, or 0.5 torr or less, for 0.5 hours or more, 0.8 hours or more, or 1 hour or more.

[0133] By ensuring that the temperature, pressure, and time conditions for the primary and secondary condensation polymerizations satisfy the aforementioned ranges, the mechanical properties and heat resistance can be improved.

[0134] The number-average molecular weight of the polymer may be 40,000 g / mol or more. For example, the number-average molecular weight of the polymer may be 43,000 g / mol or more, 48,000 g / mol or more, or 55,000 g / mol or more, and may range from 40,000 g / mol to 70,000 g / mol, 42,000 g / mol to 65,000 g / mol, 45,000 g / mol to 58,000 g / mol, or 48,000 g / mol to 55,000 g / mol. By satisfying the above range for the number-average molecular weight of the polymer, mechanical properties, processability, and productivity can be further improved.

[0135] Furthermore, according to other implementation examples, biodegradable polyester resin pellets can be produced from the polymer.

[0136] Specifically, the polymer can be cooled to 70°C or below, 50°C or below, 45°C or below, or 25°C or below, and then the cooled polymer can be cut underwater or in strands to produce pellets.

[0137] The aforementioned cutting step can be performed using any pellet cutting machine used in this industry, and the pellets can have various shapes.

[0138] [Molded products] An example of implementation is the provision of a molded product manufactured from the biodegradable polyester resin.

[0139] Specifically, the molded article is manufactured by molding a composition containing the biodegradable polyester resin by methods known in the industry, such as compounding, extrusion and stretching, extrusion and blowing, and injection molding. The molded article may, but is not limited to, an injection-molded article, an extruded article, a thin-film molded article, or a blow-molded article.

[0140] For example, the molded product may be in the form of a film or sheet that can be used as agricultural mulching film, disposable gloves, disposable film, disposable bag, food packaging material, garbage bag, etc. It may also be in the form of a fiber that can be used as a woven fabric, knitted fabric, nonwoven fabric, rope, etc., or it may be in the form of a container that can be used as a food packaging container such as a bento box. Furthermore, the molded product may also be a molded product of various shapes, such as disposable straws, cutlery (spoons), trays, forks, etc.

[0141] Furthermore, the biodegradable polyester resin can be used in a variety of fields requiring heat resistance, mechanical properties, dimensional stability, and moldability, such as packaging materials like disposable bags and food containers, and automotive interior materials, exhibiting excellent properties.

[0142] [Biodegradable polyester film] Another example of a biodegradable polyester film includes a biodegradable polyester resin, wherein the biodegradable polyester resin includes a first repeating unit comprising a first diol residue and an aromatic dicarboxylic acid residue, and a second repeating unit comprising 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 specific temperature (T°C) conditions according to formula 1 is ΔW T In this case, the ΔW of the biodegradable polyester resin 220 The percentage is 1.3% or less.

[0143] The explanation regarding the biodegradable polyester resin is as described above.

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

[0145] The tensile strength of the biodegradable polyester film may be 30 MPa or more. For example, the tensile strength of the biodegradable polyester film may be 30 MPa or more, 33 MPa or more, or 35 MPa or more, and may range from 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] Furthermore, the impact absorption energy of the biodegradable polyester film may be 5.0 kJ / m or more. For example, the impact absorption energy of the biodegradable polyester film may be 5.0 kJ / m or more, 5.3 kJ / m or more, or 5.4 kJ / m or more, and may range from 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 may 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] Furthermore, the biodegradable polyester film may satisfy the following formula 3. [Formula 3] |IV1-IV2|≦0.2 In the above 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 formula 3 is 0.2 or less, 0.19 or less, or 0.18 or less, and can be between 0.01 and 0.2, 0.01 and 0.18, 0.02 and 0.18, or 0.04 and 0.18.

[0150] The biodegradable polyester film, as demonstrated in this example, exhibits excellent quality because the change in intrinsic viscosity (IV drop), 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 aforementioned range, resulting in virtually no fume generation during the manufacturing process.

[0151] Furthermore, the thickness of the biodegradable polyester film may range from 5 μm to 200 μm. For example, the thickness of the biodegradable polyester film may be 5 μm to 160 μm, 6 μm to 130 μm, 8 μm to 115 μm, 10 μm to 100 μm, 12 μm to 90 μm, or 13 μm to 85 μm.

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

[0153] [Method for manufacturing biodegradable polyester film] Furthermore, other examples of methods for producing biodegradable polyester films may include a step of molding a composition or pellets containing a biodegradable polyester resin.

[0154] Specifically, the molding step may be, but is not limited to, a step of compounding the composition or pellets, then melt-extruding and applying electrostatic discharge, a step of compounding and then bubble-molding using blow molding equipment, or a step of compounding and then molding using an injection molding machine.

[0155] The composition or pellets may contain an electrostatic agent. Specifically, the electrostatic agent is used to reduce peening and may be a metal acetate such as magnesium acetate, sodium acetate, or calcium acetate. Peening refers to the phenomenon in which a resin-containing composition adheres to rolls or other objects during the manufacturing process, degrading its physical properties. High peening can lead to a large change in intrinsic viscosity (IV drop), which is the absolute difference between the intrinsic viscosity of the resin and the intrinsic viscosity of the film produced therefrom. This can cause fume generation, and in the extrusion process, the viscosity becomes very low and the fluidity increases, leading to a high thickness deviation, which can reduce the tensile strength, impact strength, and heat resistance of the film.

[0156] The content of the electrostatic agent may be 45 ppm or less based on the total weight of the composition or pellets containing the biodegradable polyester resin. For example, the content of the electrostatic agent 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 agent is much lower than that of conventional electrostatic agents, and since the biodegradable polyester resin used in the realization example has excellent heat resistance, even if such a small amount of electrostatic agent is used, no disconnection will occur due to electrostatic application.

[0157] Furthermore, 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 range from 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 range from 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] Furthermore, other examples of methods for producing biodegradable polyester films may include steps of drying and melt-extruding biodegradable polyester resin pellets. The description of the biodegradable polyester resin pellets is as stated above.

[0160] The drying process may be carried out at 60°C to 100°C for 2 to 12 hours. Specifically, the drying may be carried out at 62°C to 80°C, 63°C to 75°C, or 65°C to 70°C for 3 to 10 hours or 4 to 7 hours. By satisfying the above range of conditions for the pellet drying process, the quality of the biodegradable polyester film produced can be further improved.

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

[0162] (Examples) The above will be further explained in detail by the following examples. However, the following examples are for illustrative purposes only, and the scope of the examples is not limited to these.

[0163] [Manufacturing of biodegradable polyester resin pellets] (Example 1-1) (1) Steps to manufacture slurry 52 mol% of 1,4-butanediol (1,4-BDO) as the diol component and 52 mol% of terephthalic acid (TPA) as the aromatic dicarboxylic acid were added to a first slurry tank (the bottom of the slurry tank is of the anchor type, the height to the agitator at the top is 30 mm, and it is equipped with three rotating blades) in an amount of diol 1.3 relative to the dicarboxylic acid. The mixture was then stirred at 150 rpm for 30 minutes at 35°C 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 of the average particle size (D50) was 25.

[0164] Furthermore, 48 mol% of 1,4-butanediol (1,4-BDO) as the diol component and 48 mol% of adipic acid (AA) as the aliphatic dicarboxylic acid were added to a second slurry tank (the bottom of the slurry tank is anchor-type, the height to the agitator at the top is 30 mm, and it is equipped with three rotating blades) in an amount of diol 1.3 relative to the dicarboxylic acid. Then, 1000 ppm of cellulose nanocrystal (CNC with -SO3Na terminal groups, average particle size: 190 nm, particle size deviation: 25%, CelluForce) was added as nanocellulose, and the mixture was stirred at 150 rpm for 30 minutes at 35°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 of the average particle size (D50) was 20.

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

[0166] (3) Steps to manufacture polymers To the prepolymer produced in step (2) above, 200 ppm of tetrabutyl titanate (Tyzor, Dupont), a titanium-based catalyst, and 100 ppm of triethyl phosphate, a heat stabilizer, were added and stabilized for 10 minutes. Then, a primary condensation polymerization reaction was carried out at 240°C and 50 torr for 1.5 hours.

[0167] Subsequently, the primary polymerization reaction product was placed in a disc ring reactor and subjected to a secondary polymerization reaction at 240°C and 0.5 torr for 3 hours, producing a polymer with a number-average molecular weight of 60,000 g / mol. During this secondary polymerization reaction, 1,4-butanediol vapor and by-products were removed.

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

[0169] (Examples 1-2) (1) Steps to manufacture slurry 53 mol% of 1,4-butanediol (1,4-BDO) as the diol component and 53 mol% of terephthalic acid (TPA) as the aromatic dicarboxylic acid were added to a first slurry tank (the bottom of the slurry tank is of the anchor type, the height to the agitator at the top is 30 mm, and it is equipped with three rotors) in an amount of diol 1.4 relative to the dicarboxylic acid. The mixture was then stirred at 150 rpm for 30 minutes at 37°C 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 of the average particle size (D50) was 25.

[0170] Furthermore, 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 added to a second slurry tank (the bottom of the slurry tank is of the anchor type, the height to the agitator at the top is 30 mm, and it is equipped with three rotating blades) in an amount of diol 1.2 relative to the dicarboxylic acid. After adding 500 ppm of cellulose nanofiber (CNF, average particle size: 500 nm, particle size deviation: 20%, Daiichi Kogyo Seiyaku Co., Ltd.) as nanocellulose, the mixture was stirred at 150 rpm for 30 minutes at 37°C to produce a second slurry without phase separation. The average particle size (D50) of the adipic acid (AA) was 280 μm, and the standard deviation of the average particle size (D50) was 25.

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

[0172] (3) Steps to manufacture polymers To the prepolymer produced in step (2) above, 100 ppm of tetrabutyl titanate (Tyzor, Dupont), a titanium-based catalyst, and 100 ppm of triethyl phosphate, a heat stabilizer, were added and stabilized for 10 minutes. Then, a primary condensation polymerization reaction was carried out at 245°C and 30 torr for 1.5 hours.

[0173] Subsequently, the primary polymerization reaction product was placed in a disc ring reactor and subjected to a secondary polymerization reaction at 240°C and 0.5 torr for 2.5 hours while rotating to produce a polymer having a number-average molecular weight of 54,000 g / mol. During this secondary polymerization reaction, the vapor and by-products of 1,4-butanediol were removed.

[0174] Subsequently, the polymer was immersed in water and cut with an underwater cutter to produce biodegradable polyester resin pellets.

[0175] (Examples 1-3) (1) Steps to manufacture slurry 50 mol% of 1,4-butanediol (1,4-BDO) as the diol component and 50 mol% of terephthalic acid (TPA) as the aromatic dicarboxylic acid were added to a first slurry tank (the bottom of the slurry tank is anchor-type, the height to the agitator at the top is 30 mm, and it is equipped with three rotors) in an amount of diol 1.35 relative to the dicarboxylic acid. The mixture was then stirred at 150 rpm for 30 minutes at 39°C 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 of the average particle size (D50) was 25.

[0176] Furthermore, 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 added to a second slurry tank (the bottom of the slurry tank is anchor-type, the height to the agitator at the top is 30 mm, and it is equipped with three rotating blades) in an amount of diol 1.25 relative to the dicarboxylic acid. Then, 700 ppm of cellulose nanocrystal (CNC containing carboxyl groups (-COOH), average particle size: 150 nm, particle size deviation: 29%, Blue Goose Refineries) was added as nanocellulose, and the mixture was stirred at 150 rpm for 30 minutes at 39°C 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 of the average particle size (D50) was 30.

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

[0178] (3) Steps to manufacture polymers To the prepolymer produced in step (2) above, 100 ppm of tetrabutyl titanate (Tyzor, Dupont), a titanium-based catalyst, and 100 ppm of triethyl phosphate, a heat stabilizer, were added and stabilized for 10 minutes. Then, a primary condensation polymerization reaction was carried out at 235°C and 40 torr for 1.5 hours.

[0179] Subsequently, the primary polymerization reaction product was placed in a disc ring reactor and subjected to a secondary polymerization reaction at 245°C and 0.5 torr for 2.8 hours while rotating to produce a polymer having a number-average molecular weight of 55,000 g / mol. During this secondary polymerization reaction, the vapor and by-products of 1,4-butanediol were removed.

[0180] Subsequently, the polymer was immersed in water and cut with an underwater cutter to produce biodegradable polyester resin pellets.

[0181] (Examples 1-4) (1) Steps to manufacture slurry 50 mol% of 1,4-butanediol (1,4-BDO) as the diol component and 50 mol% of terephthalic acid (TPA) as the aromatic dicarboxylic acid were added to a first slurry tank (the bottom of the slurry tank is of the anchor type, the height to the agitator at the top is 30 mm, and it is equipped with three rotors) in an amount of diol 1.4 relative to the dicarboxylic acid. The mixture was then stirred at 150 rpm for 30 minutes at 40°C 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 of the average particle size (D50) was 25.

[0182] Furthermore, 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 added to a second slurry tank (the bottom of the slurry tank is of the anchor type, the height to the agitator at the top is 30 mm, and it is equipped with three rotating blades) in an amount of diol 1.3 relative to the dicarboxylic acid. The mixture was 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 of the average particle size (D50) was 20.

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

[0184] (3) Steps to manufacture polymers To the prepolymer produced in step (2) above, 200 ppm of tetrabutyl titanate (Tyzor, Dupont), a titanium-based catalyst, and 100 ppm of triethyl phosphate, a heat stabilizer, were added and stabilized for 10 minutes. Then, a primary condensation polymerization reaction was carried out at 235°C and 80 torr for 1 hour.

[0185] Subsequently, the primary polymerization reaction product was placed in a disc ring reactor and subjected to a secondary polymerization reaction at 235°C and 0.5 torr for 2.8 hours while rotating to produce a polymer having a number-average molecular weight of 50,000 g / mol. During this secondary polymerization reaction, the vapor and by-products of 1,4-butanediol were removed.

[0186] Subsequently, the polymer was immersed in water and cut with an underwater cutter to produce biodegradable polyester resin pellets.

[0187] (Examples 1-5) (1) Steps to manufacture slurry 50 mol% of 1,4-butanediol (1,4-BDO) as the diol component and 50 mol% of terephthalic acid (TPA) as the aromatic dicarboxylic acid were added to a first slurry tank (the bottom of the slurry tank is anchor-type, the height to the agitator at the top is 30 mm, and it is equipped with three rotors) in an amount of diol 1.5 relative to the dicarboxylic acid. The mixture was then stirred at 150 rpm for 30 minutes at 35°C 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 of the average particle size (D50) was 25.

[0188] Furthermore, 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 added to a second slurry tank (the bottom of the slurry tank is anchor-type, the height to the agitator at the top is 30 mm, and it is equipped with three rotating blades) in an amount of diol 1.3 relative to the dicarboxylic acid. Then, 1000 ppm of cellulose nanocrystal (CNC with -SO3Na terminal groups, average particle size: 190 nm, particle size deviation: 23%, CelluForce) was added as nanocellulose, and the mixture was stirred at 150 rpm for 30 minutes at 35°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 of the average particle size (D50) was 20.

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

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

[0191] (3) Steps to manufacture polymers To the prepolymer produced in step (2) above, 200 ppm of tetrabutyl titanate (Tyzor, Dupont), a titanium-based catalyst, and 100 ppm of triethyl phosphate, a heat stabilizer, were added and stabilized for 10 minutes. After that, a primary condensation polymerization reaction was carried out at 240°C and 100 torr for 0.5 hours.

[0192] Subsequently, the primary polymerization reaction product was placed in a disc ring reactor and subjected to a secondary polymerization reaction at 245°C and 0.5 torr for 3 hours, producing a polymer with a number-average molecular weight of 55,000 g / mol. During this secondary polymerization reaction, 1,4-butanediol vapor and by-products were removed.

[0193] Subsequently, the polymer was immersed in water and cut with an underwater cutter to produce biodegradable polyester resin pellets.

[0194] (Comparative Example 1-1) (1) Steps to manufacture slurry The first slurry and the second slurry were manufactured using the same method as in Examples 1-4 described above.

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

[0196] (3) Steps to manufacture polymers To the prepolymer produced in step (2) above, 200 ppm of tetrabutyl titanate (Tyzor, Dupont), a titanium-based catalyst, and 50 ppm of triethyl phosphate, a heat stabilizer, were added and stabilized for 10 minutes. After that, a primary condensation polymerization reaction was carried out at 265°C and 150 torr for 0.5 hours.

[0197] Subsequently, the primary polymerization reaction product was placed in a disc ring reactor and subjected to a secondary polymerization reaction at 265°C and 0.5 torr for 1.5 hours while rotating to produce a polymer having a number-average molecular weight of 38,000 g / mol. During this secondary polymerization reaction, the vapor and by-products of 1,4-butanediol were removed.

[0198] Subsequently, the polymer was immersed in water and cut with an underwater cutter to produce biodegradable polyester resin pellets.

[0199] (Comparative Example 1-2) (1) Steps to manufacture slurry 48 mol% of 1,4-butanediol (1,4-BDO) as the diol component and 48 mol% of terephthalic acid (TPA) as the aromatic dicarboxylic acid were added to a first slurry tank (the bottom of the slurry tank is of the anchor type, the height to the agitator at the top is 30 mm, and it is equipped with three rotating blades) in an amount of diol 1.1 relative to the dicarboxylic acid. The mixture was then stirred at 150 rpm for 30 minutes at 40°C 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 of the average particle size (D50) was 25.

[0200] Furthermore, 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 added to a second slurry tank (the bottom of the slurry tank is of the anchor type, the height to the agitator at the top is 30 mm, and it is equipped with three rotating blades) in an amount of diol 1.1 relative to the dicarboxylic acid. The mixture was 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 of the average particle size (D50) was 40.

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

[0202] (3) Steps to manufacture polymers To the prepolymer produced in step (2) above, 500 ppm of tetrabutyl titanate (Tyzor, Dupont), a titanium-based catalyst, and 50 ppm of triethyl phosphate, a heat stabilizer, were added and stabilized for 10 minutes. After that, a primary condensation polymerization reaction was carried out at 260°C and 300 torr for 0.5 hours.

[0203] Subsequently, the primary polymerization reaction product was placed in a disc ring reactor and subjected to a secondary polymerization reaction at 260°C and 0.5 torr for 4.5 hours while rotating to produce a polymer having a number-average molecular weight of 70,000 g / mol. During this secondary polymerization reaction, the vapor and by-products of 1,4-butanediol were removed.

[0204] Subsequently, the polymer was immersed in water and cut with an underwater cutter to produce biodegradable polyester resin pellets.

[0205] (Comparative Examples 1-3) (1) Steps to manufacture 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 added to a slurry tank (the bottom of the slurry tank is of the anchor type, the height to the agitator at the top is 30 mm, and it is equipped with three rotors) in an amount of diol 1.2 relative to the dicarboxylic acid. The mixture was then stirred at 150 rpm for 30 minutes at 40°C to produce a slurry without phase separation. The average particle size (D50) of the succinic acid (SA) was 200 μm, and the standard deviation of the average particle size (D50) was 30.

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

[0207] (3) Steps to manufacture polymers To the prepolymer produced in step (2) above, 500 ppm of tetrabutyl titanate (Tyzor, Dupont), a titanium-based catalyst, and 50 ppm of triethyl phosphate, a heat stabilizer, were added and stabilized for 10 minutes. After that, a primary condensation polymerization reaction was carried out at 265°C and 400 torr for 0.5 hours.

[0208] Subsequently, the primary polymerization reaction product was placed in a disc ring reactor and subjected to a secondary polymerization reaction at 265°C and 1.0 torr for 4.5 hours while rotating to produce a polymer having a number-average molecular weight of 40,000 g / mol. During this secondary polymerization reaction, the vapor and by-products of 1,4-butanediol were removed.

[0209] Subsequently, the polymer was immersed in water and cut with an underwater cutter to produce biodegradable polyester resin pellets.

[0210] (Comparative Examples 1-4) (1) Steps to manufacture slurry The first slurry and the second slurry were manufactured using the same method as in Examples 1-4 described above.

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

[0212] (3) Steps to manufacture polymers To the prepolymer produced in step (2) above, 500 ppm of tetrabutyl titanate (Tyzor, Dupont), a titanium-based catalyst, and 50 ppm of triethyl phosphate, a heat stabilizer, were added and stabilized for 10 minutes. Then, a primary condensation polymerization reaction was carried out at 265°C and 0.3 torr for 0.5 hours.

[0213] Subsequently, the primary polymerization reaction product was placed in a disc ring reactor and subjected to a secondary polymerization reaction at 265°C and 1.0 torr for 4.5 hours while rotating to produce a polymer with a number-average molecular weight of 28,000 g / mol. During this secondary polymerization reaction, the vapor and by-products of 1,4-butanediol were removed.

[0214] Subsequently, the polymer was immersed in water and cut with an underwater cutter to produce biodegradable polyester resin pellets.

[0215] (Example of experiment) (Experimental Example 1-1: Multivariance Index (PDI)) The polydispersity index (PDI) of the resin was calculated for the resin pellets produced in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4 according to the following formula A. [Formula A] JPEG0007909627000005.jpg1972 In 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 terminal 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, after which phenol red, an indicator, was added. Subsequently, the carboxyl groups (-COOH) of the resin were changed to -COONa using N / 10-sodium hydroxide-benzyl alcohol (primary standard solution of sodium hydroxide-benzyl alcohol). At this time, the number of carboxyl end groups (eq / ton) of the resin was measured based on the amount of N / 10-sodium hydroxide-benzyl alcohol used.

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

[0218] [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 TThis is the weight (mg) of the biodegradable polyester resin with adjusted moisture content, measured by a thermogravimetric analyzer after being left at T°C for 60 minutes.

[0219] (Experimental Example 1-4: Intrinsic Viscosity (IV1)) Two g each of the resin pellets produced in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4 was completely dissolved in 25 ml of 2-chloroform. The drop time of the sample was then 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 values ​​obtained by formula B were converted to intrinsic viscosity (IV1, dl / g) using an automatic viscometer (SS-600-L2, WITHLAB). [Formula B] JPEG0007909627000007.jpg2983 In the above formula B, B is the correction coefficient for the viscosity tube, t0 is the drop time (sec) measured using only 25 ml of 2-chloroform. t1 is the drop time (sec) measured using 2g of the resin pellet dissolved in 25ml of 2-chloroform.

[0220] [Table 1]

[0221] [Table 2]

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

[0223] Specifically, the biodegradable polyester resins of Examples 1-1 to 1-5 are produced by a pretreatment process and primary and secondary condensation polymerization reactions under specific conditions. This process appropriately adjusts the polydispersity index and the number of carboxyl end groups, resulting in improved weight loss rate and intrinsic viscosity characteristics, thus exhibiting excellent mechanical properties.

[0224] On the other hand, the resins of Comparative Examples 1-1 to 1-4 had very poor mechanical properties, particularly due to their extremely high weight loss rate, as the polydispersity index and the number of carboxyl end groups fell outside the appropriate numerical range.

[0225] [Manufacturing of biodegradable polyester film] (Example 2-1) In the resin pellets produced in Example 1-1, 10 ppm of calcium acetate, an electrostatic agent, was added, and the mixture was compounded at 180°C. Then, a biodegradable polyester film with a thickness of 400 μm was produced by melt extrusion and electrostatic application at 240°C using a T-die.

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

[0227] (Examples 2-3) A 100 μm thick biodegradable polyester film 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 spherical silica was added at 200 ppm.

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

[0229] (Examples 2-5) In the resin pellets produced in Examples 1-5, 10 ppm of calcium acetate, an electrostatic agent, was added. After compounding at 180°C, a biodegradable polyester film with a thickness of 400 μm was produced by melt extrusion and electrostatic application at 240°C using a T-die.

[0230] (Comparative Example 2-1) To the resin pellets produced in Comparative Example 1-1, 10 ppm of magnesium acetate, an electrostatic agent, was added, and the mixture was compounded at 200°C. Then, a biodegradable polyester film with a thickness of 400 μm was produced by melt extrusion and electrostatic application at 240°C using a T-die.

[0231] (Comparative Example 2-2) A 100 μm thick biodegradable polyester film 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 spherical silica was added at 200 ppm.

[0232] (Comparative Example 2-3) 200 ppm of calcium carbonate was added to the resin pellets produced in Comparative Examples 1-3, compounded at 220°C, and then molded at 240°C using an injection molding machine (EDIS 250, Hyundai Platec 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, an electrostatic agent, was added. After compounding at 200°C, a biodegradable polyester film with a thickness of 400 μm was produced by melt extrusion and electrostatic application at 240°C using a T-die.

[0234] (Example of experiment) (Experimental Example 2-1: Tensile Strength) In the films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4, test specimens were prepared according to the ASTM D638 Type V standard. After testing using an Instron universal testing machine (UTM4206-001) at a tensile speed of 100 mm / min, the tensile strength (MPa) was measured using a program built into the machine.

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

[0236] Specifically, the film was cut into 10 cm x 10 cm sections, and the amount of impact absorbed energy (kJ) was measured when the film was struck with a triangular pyramidal head (head) with a diameter of 16 mm and a height of 14 mm. This was then divided by the film thickness (m) to calculate the impact absorbed energy (kJ / m). In this process, the film thickness (μm) was converted to m, and the average of the impact absorbed energy obtained from 10 tests was calculated for each film.

[0237] (Experimental Example 2-3: Processing Suitability) The films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4 were evaluated for their processability based on the presence or absence of defects such as fumes, air bubbles, and fisheyes during the manufacturing process. In this evaluation, bubbles were observed by blowing air from below during the manufacturing process.

[0238] ○: No fumes, bubbles, or fisheyes are generated, the bubble shape is good without being biased to one side or bursting, and the resin does not adhere to rolls, etc. Δ: Some fumes, bubbles, or fisheyes may occur, or bubbles may stretch slightly to one side and become uneven, but the bubbles do not burst, and some resin adheres to the rolls, etc. ×: Numerous fumes, bubbles, or fisheyes are generated, bubbles are unevenly distributed to one side and do not form a complete shape, or bubbles burst, causing a large amount of resin to adhere to the roll.

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

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

[0241] (Experimental Example 2-5: Biodegradability) The biodegradability of the films produced in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-4 was measured by measuring the amount of carbon dioxide generated based on KS M3100-1. Specifically, an inoculum container containing only compost produced at a composting plant was prepared, and a test container was prepared by adding 5% by weight of the film relative to the dry weight of the compost to the compost.

[0242] Subsequently, the samples were cultured for 180 days under conditions of a temperature of 58±2°C, a moisture content of 50%, and an oxygen concentration of 6% or higher. The amount of carbon dioxide generated in each container was collected and titrated with phenolphthalein aqueous solution to measure the amount of carbon dioxide generated in each container. The degree of biodegradation was calculated using the measured amount of carbon dioxide generated according to the following formula C.

[0243] [Formula C] JPEG0007909627000010.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, processing suitability, 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 contain the biodegradable polyester resins of Examples 1-1 to 1-5, so it is a matter of course that they are excellent in mechanical properties such as tensile strength and impact absorption energy and biodegradability, have excellent heat resistance, have a small change value (IV drop) of intrinsic viscosity, and have a small amount of oligomers generated. Therefore, 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 contain the resins of Comparative Examples 1-1 to 1-4, so they have 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, etc., and the pinning property was very high, and the bubble stability was low, such as bubbles bursting.

Claims

1. A first repeating unit comprising a first diol residue and an aromatic dicarboxylic acid residue, It comprises a second repeating unit containing a second diol residue and an aliphatic dicarboxylic acid residue, The polydispersity index (PDI) is less than 2.

0. The weight loss rate (%) under specific temperature (T°C) conditions is given by the following formula 1: ΔW Ｔ In this case, ΔW ２２０ Biodegradable polyester resin with a content of 1.3% or less: [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 This is the weight (mg) of the biodegradable polyester resin, whose moisture content has been adjusted to 100 ppm, after being left at T°C for 60 minutes and measured using a thermogravimetric analyzer.

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

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

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

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

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

7. The ratio (X / Y) of the number of first repeating units (X) to the number of second repeating units (Y) is between 0.8 and 3.

0. The biodegradable polyester resin according to claim 1, wherein the number of carboxyl end groups in the biodegradable polyester resin is 50 eq / ton or less.

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

10. A step of preparing a slurry by pre-treating a mixture of a diol and a dicarboxylic acid, The steps include: producing a prepolymer by esterifying the slurry; A method for producing a biodegradable polyester resin, comprising the step of producing a polymer by causing a condensation polymerization reaction of the aforementioned prepolymer, The biodegradable polyester resin comprises 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 specific temperature (T °C) conditions according to the following formula 1 is ΔW Ｔ When it is set as, ΔW ２２０ is 1.3% or less, a method for producing a biodegradable polyester resin: [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 This is the weight (mg) of the biodegradable polyester resin with adjusted moisture content, measured by a thermogravimetric analyzer after being left 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 carried out by stirring the mixture of the diol and the dicarboxylic acid at 50 rpm to 200 rpm for 10 minutes or more at 25°C to 85°C.

12. The step of manufacturing the slurry is, A step of preparing a first slurry by pre-treating a mixture of the first diol and the aromatic dicarboxylic acid, A method for producing a biodegradable polyester resin according to claim 10, comprising the step of pre-treating a mixture of the second diol and the aliphatic dicarboxylic acid to produce a second slurry.

13. The step of producing the aforementioned prepolymer is, The first slurry is subjected to a primary esterification reaction at 190°C to 260°C, 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 carrying out a secondary esterification reaction at 160°C to 240°C.

14. The step of producing the aforementioned polymer is, The steps include: carrying out a primary condensation polymerization reaction of the aforementioned prepolymer at a temperature of 255°C or lower and a pressure of 1 tor to 100 tor for 0.5 hours to 3 hours; A method for producing a biodegradable polyester resin according to claim 10, comprising the step of subjecting the primary polymerization reaction product to a secondary polymerization reaction at a temperature of 210°C to 250°C while reducing the pressure to 1 torr for 0.5 hours or more.

15. A biodegradable polyester film containing a biodegradable polyester resin, The biodegradable polyester resin comprises 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 specific temperature (T°C) conditions is given by ΔW according to the following formula 1. Ｔ In this case, the ΔW of the biodegradable polyester resin ２２０ Biodegradable polyester film with a content of 1.3% or less: [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 This is the weight (mg) of the biodegradable polyester resin with adjusted moisture content, measured by a thermogravimetric analyzer after being left 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. A biodegradable polyester film according to claim 15 that satisfies the following formula 3: [Formula 3] |IV １ -IV ２ |≦0.2 In the above formula 3, IV １ This is the intrinsic viscosity (dl / g) of the biodegradable polyester resin, IV ２ This is the intrinsic viscosity (dl / g) of the biodegradable polyester film.

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